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Copyright (c) 1981-2008 by Aspen Technology, Inc. All rights reserved. 
Aspen HYSYS, Aspen HYSYS Petroleum Refining, Aspen Flare System Analyzer, and Aspen HYSYS 
Pipeline Hydraulics, are trademarks or registered trademarks of Aspen Technology, Inc., Burlington, MA.
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ThTechnical Supportv
  Online Technical Support Center ........................................................ vi
  Phone and E-mail .............................................................................. vii
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ThOnline Technical Support 
Center
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maintenance agreement can register to access the Online 
Technical Support Center at:
http://support.aspentech.com
You use the Online Technical Support Center to: 
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Registered users can also subscribe to our Technical Support e-
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ThPhone and E-mail
Customer support is also available by phone, fax, and e-mail for 
customers who have a current support contract for their 
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otherwise local and international rates apply. 
For the most up-to-date phone listings, please see the Online 
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Thviii
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The 1
Table of Contents
Technical Support..................................................... v
Online Technical Support Center ............................vi
Phone and E-mail................................................ vii
1  Operations Overview ............................................1-1
1.1 Engineering..................................................... 1-2
1.2 Operations ...................................................... 1-6
1.3 Common Property Views ..................................1-14
2  Column Operations ...............................................2-1
2.1 Column Subflowsheet ....................................... 2-4
2.2 Column Theory ...............................................2-11
2.3 Column Installation .........................................2-25
2.4 Column Property View......................................2-37
2.5 Column Specification Types ............................2-121
2.6 Column Stream Specifications.........................2-135
2.7 Column-Specific Operations ............................2-136
2.8 Running the Column ......................................2-193
2.9 Column Troubleshooting.................................2-196
2.10 References ...................................................2-201
3  Electrolyte Operations ..........................................3-1
3.1 Introduction .................................................... 3-2
3.2 Crystallizer Operation ....................................... 3-4
3.3 Neutralizer Operation.......................................3-10
3.4 Precipitator Operation......................................3-18
4  Heat Transfer Operations .....................................4-1
4.1 Air Cooler........................................................ 4-3
4.2 Cooler/Heater .................................................4-45
4.3 Fired Heater (Furnace).....................................4-62.cadfamily.com    EMail:cadserv21@hotmail.com
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The 2
4.4 Heat Exchanger4-89
4.5 LNG4-163
4.6 References4-216
5  Logical Operations5-1
5.1 Adjust5-4
5.2 Balance5-20
5.3 Boolean Operations5-29
5.4 Control Ops5-57
5.5 Digital Point5-180
5.6 Parametric Unit Operation5-190
5.7 Recycle5-199
5.8 Selector Block5-219
5.9 Set5-226
5.10 Spreadsheet5-229
5.11 Stream Cutter5-248
5.12 Transfer Function5-265
5.13 Common Options5-282
6  Piping Operations6-1
6.1 Compressible Gas Pipe6-3
6.2 Liquid-liquid Hydrocyclone6-16
6.3 Mixer6-35
6.4 Pipe Segment6-43
6.5 Relief Valve6-111
6.6 Tee6-124
6.7 Valve6-133
6.8 References6-178
7  Optimizer Operation7-1
7.1 Optimizer7-2
7.2 Original Optimizer7-5
7.3 Hyprotech SQP Optimizer7-18
7.4 MDC Optim7-23
7.5 DataRecon7-24
7.6 Selection Optimization7-24
7.7 Example: Original Optimizer7-35
7.8 Example: MNLP Optimization7-44
7.9 References7-59
8  Reactor Operations8-1
8.1 CSTR/General Reactors8-3.cadfamily.com    EMail:cadserv21@hotmail.com
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The 3
8.2 CSTR/General Reactors Property View8-5
8.3 Yield Shift Reactor8-42
8.4 Plug Flow Reactor8-74
8.5 Plug Flow Reactor (PFR) Property View8-78
9  Rotating Operations9-1
9.1 Centrifugal Compressor or Expander9-2
9.2 Reciprocating Compressor9-48
9.3 Pump9-63
9.4 References9-95
10  Separation Operations10-1
10.1 Component Splitter10-2
10.2 Separator, 3-Phase Separator, & Tank10-12
10.3 Shortcut Column10-51
10.4 References10-56
11  Solid Separation Operations11-1
11.1 Baghouse Filter11-3
11.2 Cyclone11-8
11.3 Hydrocyclone11-16
11.4 Rotary Vacuum Filter11-22
11.5 Simple Solid Separator11-29
12  Streams12-1
12.1 Energy Stream Property View12-2
12.2 Material Stream Property View12-5
13  Subflowsheet Operations13-1
13.1 Introduction13-2
13.2 Subflowsheet Property View13-3
14  Utilities14-1
14.1 Introduction14-4
14.2 Boiling Point Curves14-7
14.3 CO2 Solids14-14
14.4 Cold Properties14-17
14.5 Composite Curves Utility14-23
14.6 Critical Properties14-29
14.7 Data Reconciliation Utility14-33
14.8 Derivative Utility14-59
14.9 Dynamic Depressuring14-60
14.10Envelope Utility14-87.cadfamily.com    EMail:cadserv21@hotmail.com
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The 4
14.11FRI Tray Rating Utility14-110
14.12Hydrate Formation Utility14-126
14.13Master Phase Envelope Utility14-142
14.14Parametric Utility14-145
14.15Pipe Sizing14-172
14.16Property Balance Utility14-176
14.17Property Table14-187
14.18Tray Sizing14-196
14.19User Properties14-231
14.20Vessel Sizing14-235
14.21References14-241
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Operations Overview 1-1
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Th1  Operations Overview1-1
1.1  Engineering.................................................................................... 2
1.2  Operations ..................................................................................... 6
1.2.1  Installing Operations................................................................. 6
1.2.2  Unit Operation Property View ..................................................... 9
1.3  Common Property Views.............................................................. 14
1.3.1  Graph Control Property View.................................................... 14
1.3.2  Heat Exchanger Page.............................................................. 15
1.3.3  Holdup Page .......................................................................... 23
1.3.4  HoldUp Property View ............................................................. 24
1.3.5  Notes Page/Tab...................................................................... 27
1.3.6  Nozzles Page ......................................................................... 29
1.3.7  Stripchart Page/Tab ................................................................ 30
1.3.8  User Variables Page/Tab .......................................................... 32
1.3.10  Worksheet Tab ..................................................................... 36
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1-2 Engineering
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Th1.1 Engineering
As explained in the HYSYS User Guide and HYSYS 
Simulation Basis guide, HYSYS has been uniquely created with 
respect to the program architecture, interface design, 
engineering capabilities, and interactive operation. The 
integrated steady state and dynamic modeling capabilities, 
where the same model can be evaluated from either perspective 
with full sharing of process information, represent a significant 
advancement in the engineering software industry.
The various components that comprise HYSYS provide an 
extremely powerful approach to steady state process modeling. 
At a fundamental level, the comprehensive selection of 
operations and property methods allows you to model a wide 
range of processes with confidence. Perhaps even more 
important is how the HYSYS approach to modeling maximizes 
your return on simulation time through increased process 
understanding. The key to this is the Event Driven operation. By 
using a ‘degrees of freedom’ approach, calculations in HYSYS 
are performed automatically. HYSYS performs calculations as 
soon as unit operations and property packages have enough 
required information.
Any results, including passing partial information when a 
complete calculation cannot be performed, is propagated bi-
directionally throughout the flowsheet. What this means is that 
you can start your simulation in any location using the available 
information to its greatest advantage. Since results are available 
immediately - as calculations are performed - you gain the 
greatest understanding of each individual aspect of your 
process.1-2
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Operations Overview 1-3
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ThThe multi-flowsheet architecture of HYSYS is vital to this overall 
modeling approach. Although HYSYS has been designed to allow 
the use of multiple property packages and the creation of pre-
built templates, the greatest advantage of using multiple 
flowsheets is that they provide an extremely effective way to 
organize large processes. By breaking flowsheets into smaller 
components, you can easily isolate any aspect for detailed 
analysis. Each of these sub-processes is part of the overall 
simulation, automatically calculating like any other operation.
The design of the HYSYS interface is consistent, if not integral, 
with this approach to modeling. Access to information is the 
most important aspect of successful modeling, with accuracy 
and capabilities accepted as fundamental requirements. Not 
only can you access whatever information you need when you 
need it, but the same information can be displayed 
simultaneously in a variety of locations. Just as there is no 
standardized way to build a model, there is no unique way to 
look at results. HYSYS uses a variety of methods to display 
process information - individual property views, the PFD, 
Workbook, Databook, graphical Performance Profiles, and 
Tabular Summaries. Not only are all of these display types 
simultaneously available, but through the object-oriented 
design, every piece of displayed information is automatically 
updated whenever conditions change.
The inherent flexibility of HYSYS allows for the use of third party 
design options and custom-built unit operations. These can be 
linked to HYSYS through OLE Extensibility.
This Engineering section covers the various unit operations, 
template and column subflowsheet models, optimization, 
utilities, and dynamics. Since HYSYS is an integrated steady 
state and dynamic modeling package, the steady state and 
dynamic modeling capabilities of each unit operation are 
described successively, thus illustrating how the information is 
shared between the two approaches. In addition to the Physical 
operations, there is a chapter for Logical operations, which are 
the operations that do not physically perform heat and material 
balance calculations, but rather, impart logical relationships 
between the elements that make up your process.1-3
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1-4 Engineering
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ThThe following is a brief definition of categories used in this 
volume:
Integrated into the steady state modeling is multi-variable 
optimization. Once you have reached a converged solution, you 
can construct virtually any objective function with the Optimizer. 
There are five available solution algorithms for both 
unconstrained and constrained optimization problems, with an 
automatic backup mechanism when the flowsheet moves into a 
region of non-convergence.
HYSYS offers an assortment of utilities which can be attached to 
process streams and unit operations. These tools interact with 
the process model and provide additional information. 
In this guide, each operation is explained in its respective 
chapters for steady state and dynamic modeling. A separate 
guide has been devoted to the principles behind dynamic 
modeling. HYSYS is the first simulation package to offer 
dynamic flowsheet modeling backed up by rigorous property 
package calculations. 
HYSYS has a number of unit operations, which can be used to 
assemble flowsheets. By connecting the proper unit operations 
Term Definition
Physical 
Operations 
Governed by thermodynamics and mass/energy 
balances, as well as operation-specific relations. 
Logical 
Operations 
The Logical Operations presented in this volume are 
primarily used in Steady State mode to establish 
numerical relationships between variables. Examples 
include the Adjust and Recycle. There are, however, 
several operations such as the Spreadsheet and Set 
operation which can be used in Steady State and 
Dynamic mode.
Subflowsheets You can define processes in a subflowsheet, which can 
then be inserted as a “unit operation” into any other 
flowsheet. You have full access to the operations 
normally available in the main flowsheet. 
Columns Unlike the other unit operations, the HYSYS Column is 
contained within a separate subflowsheet, which 
appears as a single operation in the main flowsheet.
The HYSYS Dynamics license is required to use the features 
in the HYSYS dynamics mode. 
Refer to Section 1.6 - 
HYSYS Dynamics in the 
HYSYS Dynamic 
Modeling guide for more 
information.1-4
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Operations Overview 1-5
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Thand streams, you can model a wide variety of oil, gas, 
petrochemical, and chemical processes.
Included in the available operations are those which are 
governed by thermodynamics and mass/energy balances, such 
as Heat Exchangers, Separators, and Compressors, and the 
logical operations like the Adjust, Set, and Recycle. A number of 
operations are also included specifically for dynamic modeling, 
such as the Controller, Transfer Function Block, and Selector. 
The Spreadsheet is a powerful tool, which provides a link to 
nearly any flowsheet variable, allowing you to model “special” 
effects not otherwise available in HYSYS.
In modeling operations, HYSYS uses a Degrees of Freedom 
approach, which increases the flexibility with which solutions are 
obtained. For most operations, you are not constrained to 
provide information in a specific order, or even to provide a 
specific set of information. As you provide information to the 
operation, HYSYS calculates any unknowns that can be 
determined based on what you have entered.
For instance, consider the Pump operation. If you provide a 
fully-defined inlet stream to the pump, HYSYS immediately 
passes the composition and flow to the outlet. If you then 
provide a percent efficiency and pressure rise, the outlet and 
energy streams is fully defined. If, on the other hand, the 
flowrate of the inlet stream is undefined, HYSYS cannot 
calculate any outlet conditions until you provide three 
parameters, such as the efficiency, pressure rise, and work. In 
the case of the Pump operation, there are three degrees of 
freedom, thus, three parameters are required to fully define the 
outlet stream.
All information concerning a unit operation can be found on the 
tabs and pages of its property view. Each tab in the property 
view contains pages which pertain to the unit operation, such as 
its stream connections, physical parameters (for example, 
pressure drop and energy input), or dynamic parameters such 
as vessel rating and valve information.1-5
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1-6 Operations
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Th1.2 Operations
1.2.1 Installing Operations
There are a number of ways to install unit operations into your 
flowsheet. The operations which are available depends on where 
you are currently working (main flowsheet, template 
subflowsheet or column subflowsheet). If you are in the main 
flowsheet or template environments, all operations are 
available, except those associated specifically with the column, 
such as reboilers and condensers. A smaller set of operations is 
available within the column subflowsheet.
The two primary areas from which you can install operations are 
the UnitOps property view and the Object Palette.
The operations are divided into categories with each category 
containing a number of individual operations. For the main 
flowsheet, the available operations are categorized in the 
following table. 
Operation Category Types
All • All Unit Operations
Vessels • 3-Phase Separator
• Continuous Stirred Tank Reactor
• Conversion Reactor
• Equilibrium Reactor
• Gibbs Reactor
• Reboiler
• Separator
• Tank
Heat Transfer 
Equipment
• Air Cooler
• Cooler
• Fired Heater
• Heat Exchanger
• Heater
• LNG
Rotating Equipment • Compressor
• Expander
• Pump
For detailed information 
on installing unit 
operations, refer to:
• Section 8.1 - 
Installing Objects 
• Section 7.23.2 - 
Installing Streams 
or Operations 
in the HYSYS User 
Guide.1-6
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Operations Overview 1-7
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ThPiping Equipment • Aspen Hydraulics Sub-Flowsheet
• Compressible Gas Pipe
• Liquid-liquid Hydrocyclone
• Mixer
• Pipe Segment
• PIPESIM
• PIPESIM Enhanced Link
•  Aspen HYSYS Pipeline Hydraulics Extension
• Relief Valve
• Tee
• Valve
Solids Handling • Baghouse Filter
• Cyclone
• Hydrocyclone
• Rotary Vacuum Filter
• Simple Solid Separator
Reactors • Continuous-Stirred Tank Reactor (CSTR)
• Conversion Reactor
• Equilibrium Reactor
• Gibbs Reactor
• Plug Flow Reactor (PFR)
• SULSIM Extension
Prebuilt Columns • 3 Stripper Crude
• 4 Stripper Crude
• Absorber
• Distillation
• FCCU Main Fractionator
• Liquid-Liquid Extractor
• Reboiled Absorber
• Refluxed Absorber
• Three Phase Distillation
• Vacuum Resid Tower
Short Cut Columns • Component Splitter
• Shortcut Column
Sub-Flowsheets • 3 Stripper Crude
• 4 Stripper Crude
• Absorber
• Aspen Hydraulics Sub-Flowsheet
• Column Sub-Flowsheet
• Distillation
• FCCU Main Fractionator
• Liquid-Liquid Extractor
• Reboiled Absorber
• Refluxed Absorber
• Standard Sub-Flowsheet
• Three Phase Distillation
• Vacuum Resid Tower
Operation Category Types1-7
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1-8 Operations
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ThLogicals • Adjust
• Balance
• Black Oil Translator
• Boolean And
• Boolean CountDown
• Boolean CountUp
• Boolean Latch
• Boolean Not
• Boolean OffDly
• Boolean OnDly
• Boolean Or
• Boolean XOr
• Cause And Effect Matrix
• Digital Control Point
• DMCplus Controller
• External Data Linker
• MPC Controller
• Parametric Unit Operation
• PID Controller
• Ratio Controller
• Recycle
• Selector Block
• Set
• Split Range Controller
• Spreadsheet
• Stream Cutter
• Surge Controller
• Transfer Function Block
Extensions • User Defined
User Ops • User Defined
Electrolyte 
Equipment
• Neutralizer
• Precipitation
• Crystalizer
RefSYS Ops • Fluidized Catalytic Cracking
• Manipulator
• Petroleum Distillation
• Petroleum Feeder
• Petroleum Yield Shift Reactor
• Product Blender
Upstream Ops • Delumper
• Lumper
• PIPESIM 
The electrolyte operations are only available if your case is 
an electrolyte system (the selected fluid package must 
support electrolyte).
Operation Category Types
For information on the 
RefSYS operations refer 
to the RefSYS Option 
Guide.
For information on the 
Upstream operations 
refer to the Upstream 
Option Guide.1-8
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Operations Overview 1-9
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ThPrior to describing each of the unit operations, a quick overview 
of the material and energy streams is provided, as they are the 
means of transferring process information between operations.
1.2.2 Unit Operation Property 
View
Although each unit operation differs in functionality and 
operation, in general, the unit operation property view remains 
fairly consistent in its overall appearance. The figure below 
shows a generic property view for a unit operation. 
Most operation property view contains the following three 
common objects:
• Delete button. This button enables you to delete the unit 
operation from the current simulation case. Only the unit 
operation is deleted, any streams attached to the unit 
operation is left in the simulation case.
• Status bar. This bar displays messages associated to the 
calculation status of the unit operation. The messages 
also indicate the missing or incorrect data in the 
operation.
• Ignore checkbox. This checkbox enables you to toggle 
between including or excluding the unit operation in the 
simulation process calculation.
 Figure 1.1
The Name of the unit operation.The various 
pages of 
the active 
tab.
The active 
tab of the 
property 
view.1-9
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1-10 Operations
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ThTo ignore the operation during calculations, select the 
checkbox. HYSYS completely disregards the operation 
until you restore the operation to an active state by 
clearing the checkbox.
The Operation property view also contain several different tabs 
which are operation specific, however the Design, Ratings, 
Worksheet, and Dynamics tabs can usually be found in each unit 
operation property view and have similar functionality. 
Tab Description
Design Connects the feed and outlet streams to the unit operation. 
Other parameters such as pressure drop, heat flow, and 
solving method are also specified on the various pages of 
this tab.
Ratings Rates and Sizes the unit operation vessel. Specification of 
the tab is not always necessary in Steady State mode, 
however it can be used to calculate vessel hold up.
Worksheet Displays the Conditions, Properties, Composition, and 
Pressure Flow values of the streams entering and exiting 
the unit operation. 
Dynamics Sets the dynamic parameters associated with the unit 
operation such as valve sizing and pressure flow relations. 
Not relevant to steady state modelling. 
For information on dynamic modelling implications of this 
tab, refer to the HYSYS Dynamic Modeling guide.
If negative pressure drop occurs in a vessel, the operation 
will not solve and a warning message appears in the status 
bar.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.1-10
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Operations Overview 1-11
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ThObject Inspect Menu
To access the Object Inspect menu of a unit operation property 
view, right-click on any empty area of the property view.
The unit operation property view all have the following common 
commands in the Object Inspect menu:
 Figure 1.2
Command Description
Print 
Datasheet
Enables you to access the Select DataBlocks to Print 
property view. 
Open Page Enables you to open the active page into a new property 
view.
Find in PFD Enables you to locate and display the object icon in the PFD 
property view.
This command is useful if you already have access to an 
object's property view and want to see where the object is 
located in the PFD.
This command is only available in the Object Inspect menu 
of the HYSYS stream & operation property views.
Connections Enables you to access the Logical Connections For... 
Property View.
Refer to Section 9.2.2 - 
Printing Datasheets 
from the HYSYS User 
Guide for more 
information.1-11
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1-12 Operations
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ThLogical Connections For... Property View
The Logical Connections for... property view enables you to 
determine simulation dependencies between objects which are 
not otherwise shown via connecting lines on the PFD. Certain 
HYSYS operations can write to any other object and if the user 
is looking at the object being written to, they have no way of 
telling this, other than that the value might be changing. For 
example, one can determine if one spreadsheet is writing to 
another. 
The table in the Logical Connections for... property view contains 
the following columns:
• Remote Name column displays the name of the 
operation or stream being written to or read from the 
active object. 
Double-click on a particular entry of the Remote Name 
column to open the property view of the operation or 
stream.
• Remote Type column displays the operation type 
(pump, valve, stream, and so forth) of the remote object 
from the current/active property view. 
The Logical Connections for... property view is different if 
accessed from a Spreadsheet property view since there is an 
additional column (This Name) in the table. The This Name 
column displays the spreadsheet cell that contains the 
information/variable connected to the spreadsheet.
 Figure 1.31-12
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Operations Overview 1-13
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ThThe Show All checkbox enables you toggle between displaying 
or hiding all the other operations and streams that the selected 
object knows about. Duplicate connectivity information may be 
shown otherwise (either via a line on the PFD or some place else 
in a Logical operations property view, for example). Usually, you 
do not need to select this checkbox.
 
To access the Logical Connections for… view of a HYSYS PFD 
object:
1. Open the object's property view.
2. Right-click in an empty area of the object's property view. 
The Object Inspect menu associated to the object appears.
3. Select Connections command from the Object Inspect 
menu.
There is only one Show All checkbox for your HYSYS session. 
When the checkbox is changed, the current setting is 
effective for all Logical Connections For... property view.
The information displayed in the Logical Connections for... 
property view is primarily use for the Spreadsheet, Cause 
and Effect Matrix operation, Event Scheduler operation, and 
any other operations that read/write from/to these property 
views. 1-13
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1-14 Common Property Views
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Th1.3 Common Property 
Views
Each operation in HYSYS contains some common information 
and options. These information and options are grouped into 
common property views, tabs, and pages. The following sections 
describe the common objects in HYSYS operation property view.
1.3.1 Graph Control Property 
View
The Graph Control property view and its options are available for 
all plots in HYSYS.
The options are grouped into five tabs:
• Data. Contains options that enable you to modify the 
variable characteristics (type, name, colour, symbol, line 
style, and line thickness) of the plot.
• Axes. Contains options that enable you to modify the 
axes characteristics (label name, display format, and 
axes value range) of the plot.
• Title. Contains options that enable you to modify the title 
characteristics (label, font style, font colour, borders, and 
background colour) of the plot.
 Figure 1.4
Refer to Section 10.4 - 
Graph Control in the 
HYSYS User Guide for 
more information.1-14
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Operations Overview 1-15
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Th• Legend. Contains options that enable you to modify the 
legend characteristics (border, background colour, font 
style, font colour, and alignment) of the plot.
• Plot Area. Contains options that enable you to modify the 
plot characteristics (background colour, grid colour, frame 
colour, and cross hair colour) of the plot.
To access the Graph Control property view, do one of the 
following:
• Right-click any spot on an active plot and select the 
Graph Control command from the Object Inspect menu.
• Click in the plot area to make the plot the active object. 
Then, either double-click on the plot Title or Legend to 
access the respective tab of the Graph Control property 
view.
1.3.2 Heat Exchanger Page
The Heat Exchanger page in the Dynamics tab for most vessel 
unit operations in HYSYS contains the options use to configure 
heat transfer method within the unit operation. 
There are three options to choose from:
• None radio button option indicates that there is no 
energy stream or heat exchanger in the vessel. The Heat 
Exchanger page is blank and you do not have to specify 
an energy stream for the unit operation to solve.
 Figure 1.51-15
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1-16 Common Property Views
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Th• Duty radio button option indicates that there is an 
energy stream in the vessel. The Heat Exchanger page 
contains the HYSYS standard heater or cooler 
parameters and you have to specify an energy stream for 
the unit operation to solve.
• Tube Bundle radio button option indicates that there is 
heat exchanger in the vessel and enables you to simulate 
a kettle reboiler or chiller. The Heat Exchanger page 
contains the parameters used to configure a heat 
exchanger and you have to specify material streams of 
the heat exchanger for the unit operation to solve.
Duty Radio Button
When you select the Duty radio button the following options are 
available.
Heater Type Group
In the Heater Type group, there are two heating methods 
available to the general vessel operation:
• Vessel Heater
• Liquid Heater
The Tube Bundle option is only available in Dynamics mode.
The Tube Bundle option is only available for the following 
unit operations: Separator, Three Phase Separator, 
Condenser, and Reboiler.
 Figure 1.61-16
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Operations Overview 1-17
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ThIf you select the Vessel Heater radio button, 100% of the duty 
specified or calculated in the SP field is applied to the vessel’s 
holdup.
where:
Q = total heat applied to the holdup
QTotal = duty calculated from the duty source
If you select the Liquid Heater radio button, the duty applied to 
the vessel depends on the liquid level in the tank. You must 
specify the heater height in the Top of Heater and Bottom of 
Heater cells that appear with Heater Height as % Vessel 
Volume group.
The heater height is expressed as a percentage of the liquid 
level in the vessel operation. The default values are 5% for the 
Top of the Heater and 0% for the Bottom of the Heater. These 
values are used to scale the amount of duty that is applied to 
the vessel contents.
where:
L = liquid percent level (%)
T = top of heater (%)
B = bottom of heater (%)
The Percent Heat Applied can be calculated as follows:
Q = QTotal (1.1)
(1.2)
(1.3)
Q 0                      L B<( )
Q L B–
T B–
------------QTotal    B L T≤ ≤( )
Q QTotal             L T>( )
=
=
=
Percent Heat Applied Q
QTotal
--------------- 100%×=1-17
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1-18 Common Property Views
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ThIt is shown that the percent of heat applied to the vessel’s 
holdup directly varies with the surface area of liquid contacting 
the heater.
Duty Source/Source Group
In the Duty Source/Source group, you can choose whether 
HYSYS calculates the duty applied to the vessel from a direct 
energy source or from a utility source.
• If you select the Direct Q radio button, the Direct Q 
group appears, and you can directly specify the duty 
applied to the holdup in the SP field. 
 Figure 1.7
 Figure 1.8
0 20 40 60 80 100
0
20
40
60
80
100
Liquid Percent Level, L
Pe
rc
en
t 
o
f 
H
ea
t 
A
p
p
lie
d
Percent Heat Applied for a Liquid Heater
B T1-18
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Operations Overview 1-19
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ThThe following table describes the purpose of each object 
in the Direct Q group.
• If you select the Utility radio button, the Utility Properties 
group appears, and you can specify the flow of the utility 
fluid. 
The duty is then calculated using the local overall heat 
transfer coefficient, the inlet fluid conditions, and the 
process conditions. The calculated duty is then displayed 
in the SP field or the Heat Flow field. 
If you select the Heating radio button, the duty shown in 
the SP field or Heat Flow field is added to the holdup. If 
you select the Cooling radio button, the duty shown in 
the SP field or Heat Flow field is subtracted from the 
holdup.
Object Description
SP The heat flow value in this cell is the same value specified 
in the Duty field of the Parameters page on the Design tab. 
Any changes made in this cell is reflected on the Duty field 
of the Parameters page on the Design tab.
Min. 
Available
Allows you to specify the minimum amount of heat flow.
Max. 
Available
Allows you to specify the maximum amount of heat flow.
 Figure 1.9
For more information 
regarding how the utility 
option calculates duty, 
refer to Chapter 5 - 
Logical Operations.1-19
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1-20 Common Property Views
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ThTube Bundle Radio Button
When you select the Tube Bundle radio button, the following 
options are available.
The Tube Bundle option allows you to configure a shell tube heat 
exchanger (for example, kettle reboiler or kettle chiller).
• In the kettle reboiler, the process fluid is typically on the 
shell side and the process fluid is fed into a liquid "pool" 
which is heated by a number of tubes. A weir limits the 
amount of liquid in the pool. The liquid overflow is placed 
under level control and provides the main liquid product. 
The vapor is circulated back to the vessel.
• In the kettle chiller, the process fluid is typically on the 
tube side with a refrigerant on the shell side. The 
refrigerant if typically pure and cools by evaporation. The 
setup is similar to the reboiler except that there is no 
weir or level control.
 Figure 1.10
The Tube Bundle option is only available in Dynamics mode.
If you had an energy stream attached to the unit operation, 
HYSYS automatically disconnects the energy stream when 
you switch to the Tube Bundle option.1-20
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Operations Overview 1-21
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ThThe unit operation icon in the PFD also changes to indicate that 
a heat exchanger has been attached to the unit operation. 
The following table lists and describes the options available to 
configure the heat exchanger:
 Figure 1.11
Object Description
Parameters group
Tube Volume cell Allows you to specify the volume of the tubes in the 
heat exchanger.
Vessel Liquid U 
cell
Allows you to specify the heat transfer rate of the liquid 
in the shell.
Vessel Vapor U 
cell
Allows you to specify the heat transfer rate of the 
vapour in the shell.
Tube Liquid U 
cell
Allows you to specify the heat transfer rate of the liquid 
in the tube.
Tube Vapor U cell Allows you to specify the heat transfer rate of the 
vapour in the tube.
Heat Transfer 
Area cell
Allows you to specify the total heat transfer area 
between the fluid in the shell and the fluid in the tube.
Bundle Top 
Height cell
Allows you to specify the location of the top tube/
bundle based on the height from the bottom of the 
shell.
Bundle Bottom 
Height cell
Allows you to specify the location of the bottom tube/
bundle based on the height from the bottom of the 
shell.
Specs group
Tube Dp cell Allows you to specify the pressure drop within the 
tubes. You have to select the associate checkbox in 
order to specify the pressure drop.
Tube K cell Allows you to specify the pressure flow relationship 
value within the tubes. You have to select the 
associate checkbox in order to specify the pressure 
flow relationship value.1-21
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1-22 Common Property Views
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ThTube UA 
Reference Flow 
cell
Allows you to set a reference point that uses HYSYS to 
calculate a more realistic UA value. If no reference 
point is set then UA is fixed.
UA is the product of overall heat transfer multiply with 
overall heat transfer area, and depends on the flow 
rate.
If a value is specified for the Reference Flow, the heat 
transfer coefficient is proportional to 
the . The equation below is used to 
determine the actual UA:
Reference flows generally help to stabilize the system 
when you do shut downs and startups as well.
Minimum Flow 
Scale Factor cell
The ratio of mass flow at time t to reference mass flow 
is also known as flow scaled factor. The minimum flow 
scaled factor is the lowest value which the ratio is 
anticipated at low flow regions. This value can be 
expressed in a positive value or negative value. 
• A positive value ensures that some heat transfer 
still takes place at very low flows. 
• A negative value ignores heat transfer at very low 
flows.
A negative minimum flow scale factor is often used in 
shut downs if you are not interested in the results or 
run into problems shutting down the heat exchanger.
If the Minimum Flow Scale Factor is specified, the 
actual UA is calculated using the  
ratio if the ratio is greater than the Min Flow Scale 
Factor. Otherwise the Min Flow Scale Factor is used. 
Calculate K 
button
Allows you to calculate the K value based on the heat 
exchanger specifications.
Shell Dp cell Allows you to specify the pressure drop within the 
shell.
Summary group
Actual UA cell Displays the calculated UA in Dynamics mode.
Shell Liq. Percent 
Level cell
Displays the calculated liquid level in the shell at 
percentage value.
Tube Liq. Volume 
Percent cell
Allows you to specify in percentage value the volume 
of liquid in the tube.
Shell Duty cell Displays the calculated duty value in the shell.
Use Tube Trivial 
Level and 
Fraction Calc. 
radio button
Allows you to select the volume percent level variable 
for the vessel fraction calculation. 
This option uses a variable that is independent of the 
vessel shape or orientation.
Object Description
mass flow ratio( )0.8
UAactual UAspecified
mass flowcurrent
mass flowreference
-----------------------------------------⎝ ⎠
⎛ ⎞
0.8
×=
mass flowcurrent
mass flowreference
-----------------------------------------⎝ ⎠
⎛ ⎞
0.81-22
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Operations Overview 1-23
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Th1.3.3 Holdup Page
Each unit operation in HYSYS has the capacity to store material 
and energy. The Holdup page contains information regarding the 
properties, composition, and amount of the holdup.
Most Holdup page contains the following common objects/
options:
Use Tube Normal 
Level and 
Fraction Calc. 
radio button
Allows you to select the liquid percent level variable for 
the vessel fraction calculation. 
This option uses a variable that is dependant of the 
vessel shape and orientation.
ViewTubeHoldUp 
button
Allows you to access the tube HoldUp Property View.
 Figure 1.12
Objects Description
Phase column Displays the phase of the fluid available in the unit 
operation’s holdup volume.
Each available phase occupies a volume space within 
the unit operation.
Accumulation 
column
Displays the rate of change of material in the holdup 
for each phase.
Moles column Displays the amount of material in the holdup for each 
phase.
Volume column Displays the holdup volume of each phase.
Object Description1-23
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1-24 Common Property Views
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Th1.3.4 HoldUp Property View
The HoldUp property view displays the detailed calculated 
results of the holdup data in the following tabs:
• General. Displays the phase, accumulation, moles, 
volume, duty and holdup pressure of the heat exchanger. 
Select the Active Phase Flip Check checkbox to enable 
HYSYS to check if there is a phase flip between Liquid 1 
(light liquid) and Liquid 2 (heavy liquid) during 
simulation and generate a warning message whenever 
the phase flip occur. If the checkbox is clear, HYSYS 
generates a warning only on the first time the phase flip 
occur.
Total row Displays the sum of the holdup accumulation rate, 
mole value, and volume value.
Advanced button Enables you to access the unit operation’s HoldUp 
Property View that provides more detailed 
information about the holdup of that unit operation.
 Figure 1.13
Objects Description
Refer to Section 1.3.7 - 
Advanced Holdup 
Properties in the HYSYS 
Dynamic Modeling 
guide for more 
information.1-24
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Operations Overview 1-25
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Th• Nozzles. Allows you to modify nozzle configuration 
attached to the heat exchanger.
• Efficiencies. Allows you to modify the efficiency of the 
recycle, feed nozzle, and product nozzle of the heat 
exchanger.
 Figure 1.14
 Figure 1.151-25
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1-26 Common Property Views
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Th• Properties. Displays the temperature, pressure, enthalpy, 
density, and molecular weight of the holdup in the heat 
exchanger.
• Compositions. Displays the composition of the holdup in 
the heat exchanger.
 Figure 1.16
 Figure 1.171-26
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Operations Overview 1-27
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Th1.3.5 Notes Page/Tab
The Notes page/tab provides a text editor where you can record 
any comments or information regarding the specific unit 
operation or the simulation case in general.
To add a comment or information in the Notes page/tab:
1. Go to the Notes page/tab.
2. Use the options in the text editor toolbar to manipulate the 
appearance of the notes.
The following table lists and describes the options available 
in the text editor toolbar.
 Figure 1.18
Object Icon Description
Font Type Use the drop-down list to select the text type for 
the note.
Font Size Use the drop-down list to select the text size for 
the note.
Font Colour Click this icon to select the text colour for the 
note.
Bold Click this icon to bold the text for the note.
Italics Click this icon to italize the text for the note.
Underline Click this icon to underline the text for the note.
Align Left Click this icon to left justify the text for the note.
Centre Click this icon to center justify the text for the 
note.
Align Right Click this icon to right justify the text for the note.1-27
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Th3. Click in the large text field and type your comments.
The date and time when you last modified the information in 
the text field will appear below your comments.
Notes Manager
The Notes Manager lets you search for and manage notes for a 
case. To access the Notes Manager, select Notes Manager 
command from the Flowsheet menu, or press the CTRL G hot 
key.
Bullets Click this icon to apply bullets to the text for the 
note.
Insert Object Click this icon to insert an object (for example an 
image) in the note.
The information you enter in the Notes tab or page of any 
operations can also be viewed from the Notes Manager 
property view.
 Figure 1.19
Object Icon Description
Click the Plus 
icon to 
expand the 
tree browser.1-28
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ThView/Add/Edit Notes
To view, add, or edit notes for an object, select the object in the 
List of Objects group. Existing object notes appear in the Note 
group.
• To add a note, type the text in the Note group. A time 
and date stamp appears automatically.
• To format note text, use the text tools in the Note group 
toolbar. You can also insert graphics and other objects.
• Click the Clear button to delete the entire note for the 
selected object. 
• Click the View button to open the property view for the 
selected object.
Search Notes
The Notes Manager allows you to search notes in three ways:
• Select the View Objects with Notes Only checkbox (in 
the List of Objects group) to filter the list to show only 
objects that have notes.
• Select the Search notes containing the string 
checkbox, then type a search string. Only objects with 
notes containing that string appear in the object list.
You can change the search option to be case sensitive by 
selecting the Search is Case Sensitive checkbox.
The case sensitive search option is only available if you 
are searching by string.
• Select the Search notes modified since checkbox, 
then type a date. Only objects with notes modified after 
this date will appear in the object list.
1.3.6 Nozzles Page
The Nozzles page (from the Rating Tab) in most of the 
operations property view enables you to specify the elevation 
and diameter of the nozzles connected to the operation. 
The Nozzles page is only available if the HYSYS Dynamics 
license is activated.1-29
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ThDepending on the type of operation, the options in the Nozzles 
page varies. The following table lists and describes the common 
options available in the page:
1.3.7 Stripchart Page/Tab
The Stripchart page or tab allows you to select and create a strip 
chart based on a default set of variable.
 Figure 1.20
Object Description
Base Elevation 
Relative to Ground 
Level field
Enables you to specify the height/elevation 
between the bottom of the operation and the 
ground.
Diameter row Enables you to specify the diameter of the nozzle 
for each material stream flowing into and out of 
the operation.
Elevation (Base) row Enables you to specify the height/elevation 
between the nozzle and the base of the operation.
Elevation (Ground) 
row
Enables you to specify the height/elevation 
between the nozzle and the ground.
 Figure 1.21
Refer to Section 1.6.2 - 
Nozzles in the HYSYS 
Dynamic Modeling 
guide for more 
information.
Refer to Section 11.7.3 
- Strip Charts in the 
HYSYS User Guide for 
more information about 
strip charts.1-30
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ThDepending on the object property view, the strip chart sets will 
contain variables appropriate for the object. For example, the 
strip chart set ToolTip Properties for a mixer will contain the 
following variables: Product Temperature, Product Pressure, and 
Product Molar Flow. The strip chart set ToolTip Properties for 
a separator will contain the following variables: Vessel 
Temperature, Vessel Pressure, and Liquid Volume Percent.
To select the strip chart set:
1. Open the object’s property view, and access the Stripchart 
page or tab.
2. Select the strip chart set you want using the Variable Set 
drop-down list.
3. Clicking the Create Stripchart button.
The new strip chart property view appears.
If you closed the strip chart property view, you can open the 
strip chart property view again using the options in the 
Databook property view. 
 Figure 1.22
 Figure 1.23
The new strip chart is automatically named: 
objectname-DLn
where:
objectname = name of the object
n = an integer number that increases 
each time a new strip chart with the 
same objectname is created
Refer to Section 11.7 - 
Databook in the HYSYS 
User Guide for more 
information.1-31
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1-32 Common Property Views
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Th1.3.8 User Variables Page/Tab
The User Variables page or tab enables you to create and 
implement variables in the HYSYS simulation case.
The following table outlines options in the user variables 
toolbar:
 Figure 1.24
Object Icon Function
Current Variable 
Filter drop-down list
Enables you to filter the list of variables 
in the table based on the following types:
• All
• Real
• Enumeration
• Text
• Code Only
• Message
Create a New User 
Variable icon
Enables you to create a new user variable 
and access the Create a New User 
Variable property view.
Edit the Selected 
User Variable icon
Enables you to edit the configuration of 
an existing user variable in the table.
You can also open the edit property view 
of a user variable by double-clicking on 
its name in the table.
Delete the Selected 
User Variable icon
Enables you to delete the select user 
variable in the table.
HYSYS requires confirmation before 
proceeding with the deletion. If a 
password has been assigned to the User 
Variable, the password is requested 
before proceeding with the deletion.
Sort Alphabetically 
icon
Enables you to sort the user variable list 
in ascending alphabetical order.
For more information on 
the user variables, refer 
to Chapter 5 - User 
Variables in the 
HYSYS Customization 
Guide.1-32
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Operations Overview 1-33
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ThTo add a user variable:
1. Access the User Variables page or tab in the object 
property view.
2. Click the Create a New User Variable icon. 
The Create New User Variable property view appears.
3. In the Name field, type in the user variable name.
Sort by Execution 
Order icon
Enables you to sort the user variable list 
according to the order by which they are 
executed by HYSYS. 
Sorting by execution order is important if 
your user variables have order 
dependencies in their macro code. 
Normally, you should try and avoid these 
types of dependencies.
Move Selected 
Variable Up In 
Execution Order icon
Enables you to move the selected user 
variable up in execution order.
Move Selected 
Variable Down In 
Execution Order icon
Enables you to move the selected user 
variable down in the execution order. 
Show/Hide Variable 
Enabling Checkbox 
icon
Enables you to toggle between displaying 
or hiding the Variable Enabling 
checkboxes associated with each user 
variable. 
By default, the checkboxes are not 
displayed.
Object Icon Function
Create a New User 
Variable icon1-33
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Th4. Fill in the rest of the user variable parameters as indicated 
by the figure below.
You can define your own filters on the Filters tab of the User 
Variable property view.
 Figure 1.25
Code field
Allows you to add 
password 
security to the 
user variable.
Select the data 
type, dimension, 
and unit type 
using these drop-
down list.
These tabs 
contain more 
options for 
configuring the 
user variable. 1-34
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Operations Overview 1-35
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Th1.3.9 Variable Navigator 
Property View
The Variable Navigator property view enables you to browse for 
and select variable, such as selecting a process variable for a 
controller or a strip chart.
 Figure 1.26
Object Description
Flowsheet/
Case/Basis 
Object/Utility 
group
Enables you to select the flowsheet/case/basis object/
utility containing the variable you want.
This type of objects available in this group depends on 
the selection in the Navigator Scope group.
Object group Enables you to select the object containing the variable 
you want.
The list of available objects depend on the flowsheet 
you selected in the Flowsheet group.
Variable group Enables you to select the variable you want.
The list of available variables depend on the object you 
selected in the Object group.
Variable 
Specifics group
Enables you to select a specific item of the variable.
The list of available items depend on the variable you 
selected in the Variable group.
More Specific 
group
Enables you to select in detail the item of the variable 
you want.
The list of available sub-items depend on the item you 
selected in the Variable Specifics group.
Navigator Scope 
group
Enables you to select the area/location containing the 
variable you want.
Refer to Section 11.21 - 
Variable Navigator in 
the HYSYS User Guide 
for more information.1-35
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1-36 Common Property Views
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Th1.3.10 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the unit operation.
• The Conditions and Composition pages contain selected 
information from the corresponding pages of the 
Worksheet tab for the stream property view.
• The Properties page displays the property correlations of 
the inlet and outlet streams of the unit operations. The 
following is a list of the property correlations: 
Variable 
Description field
Enables you to provide a name for the selected 
variable.
OK button Enables you to confirm the selection of the variable 
and close the navigator property view.
This button is only available when you have selected 
the variable in the groups.
Add button Enables you to confirm the selection of the variable 
and keep the navigator property view open to select 
more variable.
This button is only available when the operation allows 
multiple variable selection.
Object Filter 
group
Enables you to filter the types of objects displayed in 
the Object group.
Disconnect 
button
Enables you to remove/disconnect the selected 
variable and close the property view.
This button is only available when a variable is selected 
in the navigator property view.
Close button Enables you to close the navigator property view.
This button is only available if you have selected 
multiple variable in the same navigator property view.
Cancel button Enables you to close the navigator property view 
without making any changes or variable selection.
• Vapour / Phase Fraction • Vap. Frac. (molar basis)
• Temperature • Vap. Frac. (mass basis)
• Pressure • Vap. Frac. (volume basis)
• Actual Vol. Flow • Molar Volume
• Mass Enthalpy • Act. Gas Flow
• Mass Entropy • Act. Liq. Flow
• Molecular Weight • Std. Liq. Flow
• Molar Density • Std. Gas Flow
Object Description1-36
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Th• The PF Specs page contains a summary of the stream 
property view Dynamics tab.
• Mass Density • Watson K
• Std. Ideal Liquid Mass Density • Kinematic Viscosity
• Liquid Mass Density • Cp/Cv
• Molar Heat Capacity • Lower Heating Value
• Mass Heat Capacity • Mass Lower Heating Value
• Thermal Conductivity • Liquid Fraction
• Viscosity • Partial Pressure of CO2
• Surface Tension • Avg. Liq. Density
• Specific Heat • Heat of Vap.
• Z Factor • Mass Heat of Vap.
The Heat of Vapourisation for a stream in HYSYS is defined 
as the heat required to go from saturated liquid to saturated 
vapour. 
The PF Specs page is relevant to dynamics cases only.1-37
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Th1-38
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-3 Column Operations 
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-4 Column Subflowsheet
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ThColumn Subflowsheet
The Column is a special type of subflowsheet in HYSYS. A 
subflowsheet contains equipment and streams, and exchanges 
information with the parent flowsheet through the connected 
internal and external streams. From the main simulation 
environment, the Column appears as a single, multi-feed multi-
product operation. In many cases, you can treat the column in 
exactly that manner.
You can also work inside the Column subflowsheet. You can do 
this to “focus” your attention on the Column. When you move 
into the Column build environment, the main simulation is 
“cached.” All aspects of the main environment are paused until 
you exit the Column build environment. When you return to the 
Main Environment, the Desktop re-appears as it was when you 
left it.
You can also enter the Column build environment when you 
want to create a custom column configuration. Side equipment 
such as pump arounds, side strippers, and side rectifiers can be 
added from the Column property view in the main simulation. 
However, if you want to install multiple tray sections or multiple 
columns, you need to enter the Column build environment. 
Once inside, you can access the Column-specific operations 
(Tray Sections, Heaters/Coolers, Condensers, Reboilers, and sof 
forth) and build the column as you would any other flowsheet.
If you want to create a custom column template for use in other 
simulations, on the File menu select the New command, and 
then select the Column sub-command. Since this is a column 
template, you can access the Column build environment directly 
from the Basis environment. Once you have created the 
template, you can store it on disk. Before you install the 
template in another simulation, ensure that the Use Input 
Experts checkbox in the Session Preferences property view is 
cleared.
For detailed information 
about subflowsheet 
manipulation, refer to 
Chapter 3 - Flowsheet in 
the HYSYS User Guide.-4
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Column Operations -5
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ThHaving a Column subflowsheet provides a number of 
advantages:
• isolation of the Column Solver.
• optional use of different Property Packages.
• construction of custom templates.
• ability to solve multiple towers simultaneously.
Isolation of the Column Solver
One advantage of the Column build environment is that it allows 
you to make changes, and focus on the Column without 
requiring a recalculation of the entire flowsheet. When you enter 
the Column build environment, HYSYS clears the Desktop by 
caching all property views that were open in the parent 
flowsheet. Then the property views that were open when you 
were last in the Column build environment are re-opened.
Once inside the Column build environment, you can access 
profiles, stage summaries, and other data, as well as make 
changes to Column specifications, parameters, equipment, 
efficiencies, or reactions. When you have made the necessary 
changes, simply run the Column to produce a new converged 
solution. The parent flowsheet cannot recalculate until you 
return to the parent build environment.
The subflowsheet environment permits easy access to all 
streams and operations associated with your column. 
• Click the PFD icon to view the column subflowsheet. 
• If you want to access information regarding column 
product streams, click the Workbook icon to view the 
Column workbook, which displays the Column 
information exclusively. 
While in the Column subflowsheet, you can view the 
Workbook or PFD for both the Parent flowsheet or 
subflowsheet by using the Workbooks option or PFDs option 
in the Tools menu.
In this chapter, the use of 
the Column property view 
and Column Templates are 
explained. Section  - 
Column-Specific 
Operations, describes the 
unit operations available in 
the Column build 
environment.
PFD icon
Workbook icon-5
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-6 Column Subflowsheet
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ThIndependent Fluid Package
HYSYS allows you to specify a unique fluid package for the 
Column subflowsheet. Here are some instances where a 
separate fluid package is useful:
• If a column does not use all of the components used in 
the main flowsheet, it is often advantageous to define a 
new fluid package with only the components that are 
necessary. This speeds up the column solution.
• In some cases, a different fluid package can be better 
suited to the column conditions. For example, if you want 
to redefine Interaction Parameters such that they are 
applicable for the operating range of the column.
• In Dynamic mode, different columns can operate at very 
different temperatures and pressures. With each fluid 
package, you can define a different dynamic model 
whose parameters can be regressed in the appropriate 
temperature and pressure range, thus, improving the 
accuracy and stability of the dynamic simulation.
Ability to construct Custom Column 
Configurations
Custom column configurations can be stored as templates, and 
recalled into another simulation. To create a custom template, 
on the File menu select the New command, and then select the 
Column sub-command. When you store the template, it has a 
*.col extension.
There exists a great deal of freedom when defining column 
configurations, and you can define column setups with varying 
degrees of complexity. You can use a wide array of column 
operations in a manner which is straightforward and flexible.
Complex custom columns and multiple columns can be 
simulated within a single subflowsheet using various 
combinations of subflowsheet equipment.-6
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Column Operations -7
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ThColumn arrangements are created in the same way that you 
build the main flowsheet: 
• accessing various operations.
• making the appropriate connections.
• defining the parameters.
Use of Simultaneous Solution Algorithm
The Column subflowsheet uses a simultaneous solver whereby 
all operations within the subflowsheet are solved 
simultaneously. The simultaneous solver permits you to install 
multiple unit operations within the subflowsheet (interconnected 
columns, for example) without the need for Recycle blocks.
Dynamic Mode
There are several major differences between the dynamic 
column operation and the steady state column operation. One of 
the main differences is the way in which the Column 
subflowsheet solves. 
In steady state if you are in the Column subflowsheet, 
calculations in the main flowsheet are put on Hold until the focus 
is returned to the main flowsheet. When running in dynamics, 
calculations in the main flowsheet proceed at the same time as 
those in the Column subflowsheet.
Another difference between the steady state column and the 
dynamic column is with the column specifications. Steady state 
column specifications are ignored in dynamics. To achieve the 
column specifications when using dynamics, control schemes 
must be added to the column.
Finally, although it is possible to turn off static head 
contributions for the rest of the simulation, this option does not 
apply to the column. When running a column in Dynamic mode, 
the static head contributions are always used in the column 
calculations.-7
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-8 Column Subflowsheet
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ThColumn Property View
The Column property view (the representation of the Column 
within the main or parent flowsheet) essentially provides you 
with complete access to the Column. 
From the Column property view, you can change feed and 
product connections, specifications, parameters, pressures, 
estimates, efficiencies, reactions, side operations, and view the 
Profiles, Work Sheet, and Summary. You can also run the 
column from the main flowsheet just as you would from the 
Column subflowsheet.
If you want to make a minor change to a column operation (for 
instance, resize a condenser) you can call up that operation 
using the Object Navigator without entering the Column 
subflowsheet. Major changes, such as adding a second tray 
section, require you to enter the Column subflowsheet. 
 Figure 2.1
Side equipment (for example, pump arounds and side 
strippers) is added from the Column property view.
For more information, 
refer to Section  - 
Column Property View.-8
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Column Operations -9
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ThTo access to the Column build environment, click the Column 
Environment button at the bottom of the Column property view.
Main Flowsheet and Column 
Subflowsheet Relationship
Unlike other unit operations, the Column contains its own 
subflowsheet, which in turn, is contained in the Parent (usually 
the main) flowsheet. When you are working in the parent 
flowsheet, the Column appears just as any other unit operation, 
with multiple input and output streams, and various adjustable 
parameters.
When you install a Column, HYSYS creates a subflowsheet 
containing all operations and streams associated with the 
template you have chosen. This subflowsheet operates as a unit 
operation in the main flowsheet. Figure 2.2 shows this concept 
of a Column subflowsheet within a main flowsheet.
Main Flowsheet / Subflowsheet 
Concept
Consider a simple absorber in which you want to remove CO2 
from a gas stream using H2O as the solvent. A typical approach 
to setting up the problem would be as follows:
1. Create the gas feed stream, FeedGas, and the water solvent 
stream, WaterIn, in the main flowsheet.
2. Click the Absorber icon from the Object Palette.
Enter the Column subflowsheet to add new pieces of 
equipment, such as additional Tray Sections or Reboilers.
If you make a change to the Column while you are working in 
the parent, or main build environment, both the Column and 
the parent flowsheets are automatically recalculated.
Absorber icon-9
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-10 Column Subflowsheet
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Th3. Specify the stream names, number of trays, pressures, 
estimates, and specifications. You must also specify the 
names of the outlet streams, CleanGas and WaterOut.
4. Run the Column from the main flowsheet Column property 
view.
When you connected the streams to the tower, HYSYS created 
internal streams with the same names. The Connection Points or 
“Labels” serve to connect the main flowsheet streams to the 
subflowsheet streams and facilitate the information transfer 
between the two flowsheets. 
For instance, the main flowsheet stream WaterIn is connected 
to the subflowsheet stream WaterIn.
A subflowsheet stream that is connected to a stream in the 
main flowsheet is automatically given the same name with 
“@subflowsheet tag” attached at the end of the name.
An example is the stream named “WaterIn” has the 
subflowsheet stream named “WaterIn@Col1”.
 Figure 2.2-10
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Column Operations -11
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ThWhen working in the main build environment, you “see” the 
Column just as any other unit operation, with a property view 
containing parameters such as the number of stages, and top 
and bottom pressures. If you change one of these parameters, 
the subflowsheet recalculates (just as if you had clicked the Run 
button); the main flowsheet also recalculates once a new 
column solution is reached. 
However, if you are inside the Column subflowsheet build 
environment, you are working in an entirely different flowsheet. 
To make a major change to the Column such as adding a 
reboiler, you must enter the Column subflowsheet build 
environment. When you enter this environment, the main 
flowsheet is put on “hold” until you return.
Column Theory
Multi-stage fractionation towers, such as crude and vacuum 
distillation units, reboiled demethanizers, and extractive 
distillation columns, are the most complex unit operations that 
HYSYS simulates. Depending on the system being simulated, 
each of these towers consists of a series of equilibrium or non-
equilibrium flash stages. The vapour leaving each stage flows to 
the stage above and the liquid from the stage flows to the stage 
below. A stage can have one or more feed streams flowing onto 
it, liquid or vapour products withdrawn from it, and can be 
heated or cooled with a side exchanger. 
The connected streams do not necessarily have the same 
values. All specified values are identical, but calculated 
stream variables can be different depending on the fluid 
packages and transfer basis (defined on the Flowsheet tab).
If you delete any streams connected to the column in the 
main flowsheet, these streams are also deleted in the 
Column subflowsheet.
For information regarding 
the electrolyte column 
theory, refer to Section 
1.6.8 - Aspen HYSYS 
Column Operation in 
the HYSYS OLI 
Interface Reference 
Guide.-11
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-12 Column Theory
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ThThe following figure shows a typical stage j in a Column using 
the top-down stage numbering scheme. The stage above is j-1, 
while the stage below is j+1. The stream nomenclature is shown 
in the figure below.
More complex towers can have pump arounds, which withdraw 
liquid from one stage of the tower and typically return it to a 
stage farther up the column. Small auxiliary towers, called 
sidestrippers, can be used on some towers to help purify side 
liquid products. With the exception of Crude distillation towers, 
very few columns have all of these items, but virtually any type 
of column can be simulated with the appropriate combination of 
features.
It is important to note that the Column operation by itself is 
capable of handling all the different fractionation applications. 
HYSYS has the capability to run cryogenic towers, high pressure 
TEG absorption systems, sour water strippers, lean oil 
absorbers, complex crude towers, highly non-ideal azeotropic 
distillation columns, and so forth. There are no programmed 
limits for the number of components and stages. The size of the 
column which you can solve depends on your hardware 
configuration and the amount of computer memory you have 
available.
The column is unique among the unit operations in the methods 
used for calculations. There are several additional underlying 
equations which are used in the column.
 Figure 2.3
Fj
Lj-1 Vj
VSDj
Qj
Vj+1 Lj
LSDj
Stage j
Rj
F = Stage feed stream
L = Liquid stream 
travelling to stage below
V = Vapor stream 
travelling to stage above
LSD = Liquid side draw 
from stage
VSD = Vapor side draw 
from stage
Q = Energy stream 
entering stage-12
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Column Operations -13
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ThThe Francis Weir equation is the starting point for calculating the 
liquid flowrate leaving a tray:
where:  
LN = liquid flowrate leaving tray N
C = units conversion constant
 = density of liquid on tray
lw = weir length
h = height of liquid above weir
The vapour flowrate leaving a tray is determined by the 
resistance equation:
where:  
Fvap = vapour flowrate leaving tray N
k = conductance, which is a constant representing the 
reciprocal of resistance to flow
 = dry hole pressure drop
(2.1)
(2.2)
For columns the conductance, k, is proportional to the 
square of the column diameter.
The pressure drop across a stage is determined by summing 
the static head and the frictional losses.
LN Cρlwh1.5=
ρ
Fvap k PfrictionΔ=
PfrictionΔ-13
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-14 Column Theory
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ThIt is possible to use column stage efficiencies when running a 
column in dynamics. The efficiency is equivalent to bypassing a 
portion of the vapour around the liquid phase, as shown in the 
figure below, where n is the specified efficiency.
HYSYS has the ability to model both weeping and flooding inside 
the column. If  is very small, the stage exhibits weeping. 
Therefore it is possible to have a liquid flow to the stage below 
even if the liquid height over the weir is zero.
For the flooding condition, the bulk liquid volume approaches 
the tray volume. This can be observed on the Holdup page in the 
Dynamics tab, of either the Column Runner or the Tray Section 
property view.
Three Phase Theory
For non-ideal systems with more than two components, 
boundaries can exist in the form of azeotropes, which a simple 
distillation system cannot cross. The formation of azeotropes in 
 Figure 2.4
PfrictionΔ-14
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Column Operations -15
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Tha three phase system provides a thermodynamic barrier to 
separating chemical mixtures.
Distillation schemes for non-ideal systems are often difficult to 
converge without very accurate initial guesses. To aid in the 
initialization of towers, a Three Phase Input Expert is available 
to initialize temperatures, flows, and compositions. 
Detection of Three Phases
Whenever your Column converges, HYSYS automatically 
performs a Three Phase Flash on the top stage. If a second 
liquid phase is detected, and no associated water draw is found, 
a warning message appears. 
If there is a water draw, HYSYS checks the next stage for a 
second liquid phase, with the same results as above. This 
continues down the Tower until a stage is found that is two 
phase only.
HYSYS always indicates the existence of the second liquid 
phase. This continues until the Column reverts to VLE operation, 
or all applicable stages have water draws placed on them.
For non-ideal multicomponent systems, DISTIL is an 
excellent tool for determining process viability. This 
conceptual design software application also determines the 
optimal feed tray location and allows direct export of column 
specifications to HYSYS for use as an initial estimate. 
Contact your local AspenTech representative for details.
Look at the Trace Window for column convergence 
messages.
If there is a three phase stage below a stage that was found 
to be two phase, the three phase stage is not detected 
because the checking would have ended in the previous two 
phase stage. 
Refer to Section  - 
Templates for further 
details on the three phase 
capabilities in HYSYS.-15
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-16 Column Theory
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ThInitial Estimates
Initial estimates are optional values that you provide to help the 
HYSYS algorithm converge to a solution. The better your 
estimates, the quicker HYSYS converges. 
There are three ways for you to provide the column with initial 
estimates:
• Provide the estimate values when you first build the 
column.
• Go to the Profiles or Estimates page on the Parameters 
tab to provide the estimate values.
• Go to the Monitor or Specs page on the Design tab to 
provide values for the default specifications or add your 
own specifications.
It is important to remember, when the column starts to solve for 
the first time or after the column has been reset, the 
specification values are also initial estimates. So if you replaced 
one of the original default specifications (overhead vapour flow, 
side liquid draw or reflux ratio) with a new active specification, 
the new specification value is used as initial estimates. For this 
reason it is recommended you provide reasonable specification 
values initially even if you can replace them while the column is 
solving or after the column has solved.    
Temperatures
Temperature estimates can be given for any stage in the 
column, including the condenser and reboiler, using the Profiles 
page in the Parameters tab of the Column property view. 
Intermediate temperatures are estimated by linear 
interpolation. When large temperature changes occur across the 
condenser or bottom reboiler, it would be helpful to provide an 
Although HYSYS does not require any estimates to converge 
to a solution, reasonable estimates help in the convergence 
process.
Refer to Section  - 
Templates for more 
information regarding 
default specifications.-16
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Column Operations -17
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Thestimate for the top and bottom trays in the tray section. 
Mixing Rules at Feed Stages
When a feed stream is introduced onto a stage of the column, 
the following sequence is employed to establish the resulting 
internal product streams:
1. The entire component flow (liquid and vapour phase) of the 
feed stream is added to the component flows of the internal 
vapour and liquid phases entering the stage.
2. The total enthalpy (vapour and liquid phases) of the feed 
stream is added to the enthalpies of the internal vapour and 
liquid streams entering the stage. 
3. HYSYS flashes the combined mixture based on the total 
enthalpy at the stage Pressure. The results of this process 
produce the conditions and composition of the vapour and 
liquid phases leaving the stage.
In most physical situations, the vapour phase of a feed stream 
does not come in close contact with the liquid on its feed stage. 
However if this is the case, the column allows you to split all 
material inlet streams into their phase components before being 
fed to the column. The Split Inlets checkbox can be selected in 
the Setup page of the Flowsheet tab. You can also set all the 
feed streams to a column to always split, by selecting the 
appropriate checkbox in the Options page from the Simulation 
tab of the Session Preferences property view.
Basic Column Parameters
Regardless of the type of column, the Basic Column Parameters 
remain at their input values during convergence.
If the overhead product is a subcooled liquid, it is best to 
specify an estimated bubble-point temperature for the 
condenser rather than the subcooled temperature.-17
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-18 Column Theory
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ThPressure
The pressure profile in a Column Tray Section is calculated using 
your specifications. You can either explicitly enter all stage 
pressures or enter the top and bottom tray pressures (and any 
intermediate pressures) such that HYSYS can interpolate 
between the specified values to determine the pressure profile. 
Simple linear interpolation is used to calculate the pressures on 
stages which are not explicitly specified. 
You can enter the condenser and reboiler pressure drops 
explicitly within the appropriate operation property view. Default 
pressure drops for the condenser and reboiler are zero, and a 
non-zero value is not necessary to produce a converged 
solution.
If the pressure of a Column product stream (including side 
vapour or liquid draws, side stripper bottom streams, or internal 
stream assignments) is set (either by specification or 
calculation) prior to running the Column, HYSYS “backs” this 
value into the column and uses this value for the convergence 
process. If you do specify a stream pressure that allows HYSYS 
to calculate the column pressure profile, it is not necessary to 
specify another value within the column property view. If you 
later change the pressure of an attached stream, the Column is 
rerun.  
Number of Stages
The number of stages that you specify for the tray section does 
not include the condenser and bottom reboiler, if present. If 
sidestrippers are to be added to the column, their stages are not 
included in this number. By default, HYSYS numbers stages 
from the top down. If you want, you can change the numbering 
Recall that whenever a change is made in a stream, HYSYS 
checks all operations attached to that stream and 
recalculates as required.-18
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Column Operations -19
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Thscheme to bottom-up by selecting this scheme on the 
Connections page of the Design tab.
HYSYS initially treats the stages as being ideal. If you want your 
stages to be treated as real stages, you must specify efficiencies 
on the Efficiencies page of the Parameters tab. Once you provide 
efficiencies for the stages, even if the value you specify is 1, 
HYSYS treats the stages as being real.
Stream
The feed stream and product stream location, conditions, and 
composition are treated as Basic Column Parameters during 
convergence.
Pressure Flow
In the following sections, the pressure flow specifications 
presented are the recommended configurations if no other 
equipment, such as side strippers, side draws, heat exchanger, 
and so forth, are connected. Other combinations of pressure 
flow specifications are possible, however they can lead to less 
stable configurations.
Regardless of the pressure flow specification configuration, 
when performing detailed dynamic modeling it is recommended 
that at least valves be added to all boundary streams. Once 
valves have been added, the resulting boundary streams can all 
be specified with pressure specifications, and, where necessary, 
flow controlled with flow controllers.
Absorber
The basic Absorber column has two inlet and two exit streams. 
When used alone, the Absorber has four boundary streams and 
so requires four Pressure Flow specifications. A pressure 
specification is always required for the liquid product stream 
leaving the bottom of the column. A second pressure 
specification should be added to the vapour product of the -19
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-20 Column Theory
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Thcolumn, with the two feed streams having flow specifications.
If there are down stream unit operations attached to the liquid 
product stream, then a column sump needs to be simulated. 
There are several methods for simulating the column sump. A 
simple solution is to use a reboiled absorber, with the reboiler 
duty stream specified as zero in place of the absorber. Another 
option is to feed the liquid product stream directly into a 
separator, and return the separator vapour product to the 
bottom stage of the column.
 Figure 2.5
The column shows the 
recommended 
pressure flow 
specifications for a 
stand alone absorber 
column.-20
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Column Operations -21
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ThRefluxed Absorber
The basic Refluxed Absorber column has a single inlet and two 
or three exit streams, depending on the condenser 
configuration. When used alone, the Refluxed Absorber has 
three or four boundary streams (depending on the condenser) 
and requires four or five pressure-flow specifications; generally 
two pressure and three flow specifications. A pressure 
specification is always required for the liquid product stream 
leaving the bottom of the column. The extra specification is 
required due to the reflux stream and is discussed in Section  - 
Column-Specific Operations.
If there are down stream unit operations attached to the liquid 
product stream, then a column sump needs to be simulated. 
There are several methods for simulating the column sump. A 
simple solution is to use a distillation column, with the reboiler 
duty stream specified as zero in place of the refluxed absorber. 
Another option is to feed the liquid product stream directly into 
a separator, and return the separator vapour product to the 
bottom stage of the column.
 Figure 2.6
The column shows the 
recommended 
pressure flow 
specifications for a 
stand alone refluxed 
absorber with a partial 
condenser.-21
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-22 Column Theory
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ThReboiled Absorber
A Reboiled Absorber column has a single inlet and two exit 
streams. When used alone, the Reboiled Absorber has three 
boundary streams and so requires three Pressure Flow 
specifications; one pressure and two flow specifications. A 
pressure specification is always required for the vapour product 
leaving the column.
Distillation Column
The basic Distillation column has one inlet and two or three exit 
streams, depending on the condenser configuration.When used 
alone, the Distillation column has three or four boundary 
streams but requires four or five pressure-flow specifications; 
generally one pressure and three or four flow specifications. The 
extra pressure-flow specification is required due to the reflux 
stream, and is discussed in Section  - Column-Specific 
Operations.
 Figure 2.7
The column shows the 
recommended 
pressure flow 
specifications for a 
stand alone reboiled 
absorber.-22
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Column Operations -23
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ThThe Three Phase Distillation column is similar to the basic 
Distillation column except it has three or four exit streams. So 
when used alone, the Three Phase Distillation column has four 
to five boundary streams, but requires five or six pressure-flow 
specifications; generally one pressure and four to five flow 
specifications.
Condenser and Reboiler
The following sections provide some recommended pressure-
flow specifications for simple dynamic modeling only. The use of 
flow specifications on reflux streams is not recommended for 
detailed modeling. If the condenser liquid level goes to zero, a 
mass flow specification results in a large volumetric flow 
because the stream is a vapour.
It is highly recommended that the proper equipment be added 
to the reflux stream (for example pumps, valves, and so forth). 
In all cases, level control for the condenser should be used to 
ensure a proper liquid level.
 Figure 2.8
The column shows the 
recommended pressure-flow 
specifications for a stand alone 
three phase distillation column 
with a partial condenser.
The column shows the 
recommended pressure-flow 
specifications for a stand alone 
distillation column with a partial 
condenser.-23
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-24 Column Theory
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ThPartial Condenser
The partial condenser has three exit streams:
• overhead vapour 
• reflux 
• distillate 
All three exit streams must be specified when attached to the 
main tray section. One pressure specification is recommended 
for the vapour stream, and one flow specification for either of 
the liquid product streams. The final pressure flow specification 
can be a second flow specification on the remaining liquid 
product stream, or the Reflux Flow/Total Liquid Flow value on 
the Specs page of the Dynamics tab of the condenser can be 
specified.
Fully-Refluxed Condenser
The Fully-Refluxed condenser has two exit streams: 
• overhead vapour
• reflux
A pressure specification is required for the overhead vapour 
stream, and a flow specification is required for the reflux 
stream.
Total Condenser
A Total condenser has two exit streams:
• reflux 
• distillate 
There are several possible configurations of pressure flow 
specifications for this type of condenser. A flow specification can 
be used for the reflux stream and a pressure flow spec can be 
used for the distillate stream. Two flow specifications can be 
used, however, it is suggested that a vessel pressure controller 
be setup with the condenser duty as the operating variable.-24
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Column Operations -25
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ThReboiler
The Reboiler has two exit streams: 
• boilup vapour 
• bottoms liquid
Only one exit stream can be specified. If a pressure constraint is 
specified elsewhere in the column, this exit stream must be 
specified with a flow rate.
Column Installation
The first step in installing a Column is deciding which type you 
want to install. Your choice depends on the type of equipment 
(for example, reboilers and condensers) your Column requires. 
HYSYS has several basic Column templates (pre-constructed 
column configurations) which can be used for installing a new 
Column. The most basic Column types are described in the table 
below.
Basic Column Types Icon Description
Absorber Tray section only.
Liquid-Liquid 
Extractor
Tray section only.
Reboiled Absorber Tray section and a bottom stage 
reboiler.
Refluxed Absorber Tray section and an overhead 
condenser.
Distillation Tray section with both a reboiler and 
condenser.
Three Phase 
Distillation
Tray section, three-phase condenser, 
reboiler. Condenser can be either 
chemical or hydrocarbon specific.-25
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-26 Column Installation
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ThThere are two ways that you can add a basic Column type to 
your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access UnitOps property view by pressing F12.
2. Click the Prebuilt Columns radio button.
3. From the list of available unit operations, select the column 
type.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the column type icon you want to install.
The Input Expert property view appears. 
There are also more complex Column types, which are described 
in the table below.
To add a complex column type to your simulation:
1. In the Flowsheet menu, click the Add Operation command. 
The UnitOps property view appears.
You can also access UnitOps property view by pressing F12.
Complex Column Types Description
3 Sidestripper Crude 
Column
Tray section, reboiler, condenser, 3 
sidestrippers, and 3 corresponding pump 
around circuits.
4 Sidestripper Crude 
Column 
Tray section, reboiler, condenser, an 
uppermost reboiled sidestripper, 3 steam-
stripped lower sidestrippers, and 3 
corresponding pump around circuits.
FCCU Main Fractionator Tray section, condenser, an upper pump 
around reflux circuit and product draw, a mid-
column two-product-stream sidestripper, a 
lower pump around reflux circuit and product 
draw, and a quench pump around circuit at 
the bottom of the column.
Vacuum Reside Tower Tray section, 2 side product draws with pump 
around reflux circuits and a wash oil-cooled 
steam stripping section below the flash zone.
Refer to Section  - 
Input Experts for more 
information.-26
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Column Operations -27
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Th2. Click the Prebuilt Columns radio button.
3. From the list of available unit operations, select the column 
type.
4. Click the Add button. The column property view appears.
Input Experts
Input Experts guide you through the installation of a Column. 
The Input Experts are available for the following six standard 
column templates: 
• Absorber
• Liquid-Liquid Extractor
• Reboiled Absorber
• Refluxed Absorber
• Distillation
• Three Phase Distillation
Details related to each column template are outlined in Section  
- Templates. Each Input Expert contains a series of input pages 
whereby you must specify the required information for the page 
before advancing to the next one. When you have worked 
through all the pages, you have specified the basic information 
required to build your column. You are then placed in the 
Column property view which gives comprehensive access to 
most of the column features.
It is not necessary to use the Input Experts to install a column. 
You can disable and enable the Input Experts option on the 
Options page in the Simulation tab of the Session Preferences 
property view. 
If you do not use the Input Experts, you move directly to the 
Column property view when you install a new column.
Refer to Chapter 12 - 
Session Preferences in 
the HYSYS User Guide 
for details on how to 
access the Session 
Preferences property 
view.-27
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-28 Column Installation
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ThTemplates
HYSYS contains a number of column templates which have been 
designed to simplify the installation of columns.
A Column Template is a pre-constructed configuration or 
“blueprint” of a common type of Column, including Absorbers, 
Reboiled and Refluxed Absorbers, Distillation Towers, and Crude 
Columns. A Column Template contains the unit operations and 
streams that are necessary for defining the particular column 
type, as well as a default set of specifications.
All Column templates can be viewed by opening the UnitOps 
property view and selecting the Prebuilt Columns radio button.
When you add a new Column, HYSYS gives you a choice of the 
available templates. Simply select the template that most 
closely matches your column configuration, provide the 
necessary input in the Input Expert property view (if applicable), 
and HYSYS installs the equipment and streams for you in a new 
Column subflowsheet. Stream connections are already in place, 
and HYSYS provides default names for all internal streams and 
equipment. You can then make modifications by adding, 
removing or changing the names of any streams or operations 
to suit your specific requirements.
 Figure 2.9-28
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Column Operations -29
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ThClicking the Side Ops button on the final page of the Column 
Input Expert opens the Side Operations Input Expert wizard, 
which guides you through the process of adding a side operation 
to your column.
In addition to the basic Column Templates which are included 
with HYSYS, you can create custom Templates containing 
Column configurations that you commonly use.
HYSYS Column Conventions
Column Tray Sections, Overhead Condensers, and Bottom 
Reboilers are each defined as individual unit operations. 
Condensers and Reboilers are not numbered stages, as they are 
considered to be separate from the Tray Section.
The following are some of the conventions, definitions, and 
descriptions of the basic columns:
By making the individual components of the column separate 
pieces of equipment, there is easier access to equipment 
information, as well as the streams connecting them.
Column Component Description
Tray Section A HYSYS unit operation that represents the series 
of equilibrium trays in a Column. 
Stages Stages are numbered from the top down or from 
the bottom up, depending on your preference. 
The top tray is 1, and the bottom tray is N for the 
top-down numbering scheme. The stage 
numbering preference can be selected on the 
Connections page of the Design tab on the 
Column property view.
Overhead Vapor 
Product
The overhead vapour product is the vapour 
leaving the top tray of the Tray Section in simple 
Absorbers and Reboiled Absorbers. In Refluxed 
Absorbers and Distillation Towers, the overhead 
vapour product is the vapour leaving the 
Condenser.
Overhead Liquid 
Product
The overhead liquid product is the Distillate 
leaving the Condenser in Refluxed Absorbers and 
Distillation Towers. There is no top liquid product 
in simple Absorbers and Reboiled Absorbers.-29
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-30 Column Installation
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ThDefault Replaceable Specifications
Replaceable specifications are the values, which the Column 
convergence algorithm is trying to meet. When you select a 
particular Column template, or as you add side equipment, 
HYSYS creates default specifications. You can use the 
specifications that HYSYS provides, or replace these 
specifications with others more suited to your requirements.
The available default replaceable specifications are dependent 
on the Basic Column type (template) that you have chosen. The 
default specifications for the four basic column templates are 
combinations of the following:
• Overhead vapour flowrate
• Distillate flowrate
• Bottoms flowrate
• Reflux ratio
• Reflux rate
The provided templates contain only pre-named internal 
streams (streams which are both a feed and product). For 
instance, the Reflux stream, which is named by HYSYS, is a 
product from the Condenser and a feed to the top tray of the 
Bottom Liquid 
Product
The bottom liquid product is the liquid leaving the 
bottom tray of the Tray Section in simple 
Absorbers and Refluxed Absorbers. In Reboiled 
Absorbers and Distillation Columns, the bottom 
liquid product is the liquid leaving the Reboiler.
Overhead Condenser An Overhead Condenser represents a combined 
Cooler and separation stage, and is not given a 
stage number.
Bottom Reboiler A Bottom Reboiler represents a combined heater 
and separation stage, and is not given a stage 
number.
The specifications in HYSYS can be set as specifications or 
changed to estimates.
Column Component Description
Refer to the Monitor 
Page and Specs Page 
in Section  - Design 
Tab for more 
information.-30
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Column Operations -31
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ThTray Section.
In the following schematics, you specify the feed and product 
streams, including duty streams.
Absorber Template
The only unit operation contained in the Absorber is the Tray 
Section, and the only streams are the overhead vapour and 
bottom liquid products. 
There are no available specifications for the Absorber, which is 
the base case for all tower configurations. The conditions and 
composition of the column feed stream, as well as the operating 
pressure, define the resulting converged solution. The 
converged solution includes the conditions and composition of 
the vapour and liquid product streams. 
The pressure for a tray section stage, condenser or reboiler 
can be specified at any time on the Pressures page of the 
Column property view.
 Figure 2.10
The Liquid-Liquid Extraction Template is identical to the 
Absorber Template.
The remaining Column templates have additional equipment, 
thus increasing the number of required specifications.
A schematic 
representation of the 
Absorber.-31
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-32 Column Installation
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ThReboiled Absorber Template
The Reboiled Absorber template consists of a tray section and a 
bottom reboiler. Two additional streams connecting the Reboiler 
to the Tray Section are also included in the template.
When you install a Reboiled Absorber (in other words, add only 
a Reboiler to the Tray Section), you increase the number of 
required specifications by one over the Base Case. As there is no 
overhead liquid, the default specification in this case is the 
overhead vapour flow rate.
Refluxed Absorber Template
The Refluxed Absorber template contains a Tray Section and an 
overhead Condenser (partial or total). Additional material 
streams associated with the Condenser are also included in the 
template. For example, the vapour entering the Condenser from 
the top tray is named to Condenser by default, and the liquid 
returning to the Tray Section is the Reflux.
 Figure 2.11
 Figure 2.12-32
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Column Operations -33
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ThWhen you install a Refluxed Absorber, you are adding only a 
Condenser to the base case. Specifying a partial condenser 
increases the number of required specifications by two over the 
Base Case. The default specifications are the overhead vapour 
flow rate, and the side liquid (Distillate) draw. Specifying a total 
condenser results in only one available specification, since there 
is no overhead vapour product.
Either of the overhead vapour or distillate flow rates can be 
specified as zero, which creates three possible combinations for 
these two specifications. Each combination defines a different 
set of operating conditions. The three possible Refluxed 
Absorber configurations are listed below:
• Partial condenser with vapour overhead but no side liquid 
(distillate) draw.
• Partial condenser with both vapour overhead and 
distillate draws.
• Total condenser with distillate but no vapour overhead 
draw.
Distillation Template
If you select the Distillation template, HYSYS creates a Column 
with both a Reboiler and Condenser. The equipment and streams 
in the Distillation template are therefore a combination of the 
Reboiled Absorber and Refluxed Absorber Templates
 Figure 2.13-33
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-34 Column Installation
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ThReflux Ratio
The number of specifications for a column with both a Reboiler 
and Condenser depends on the condenser type. For a partial 
condenser, you must specify three specifications. For a total 
condenser, you must specify two specifications. The third default 
specification (in addition to Overhead Vapor Flow Rate and Side 
Liquid Draw) is the Reflux Ratio.
The Reflux Ratio is defined as the ratio of the liquid returning to 
the tray section divided by the total flow of the products (see 
the figure above). If a water draw is present, its flow is not 
included in the ratio.
As with the Refluxed Absorber, the Distillation template can have 
either a Partial or Total Condenser. Choosing a Partial Condenser 
results in three replaceable specifications, while a Total 
Condenser results in two replaceable specifications.
The pressure in the tower is, in essence, a replaceable 
specification, in that you can change the pressure for any stage 
from the Column property view.
 Figure 2.14
The pressure remains fixed during the Column calculations.-34
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Column Operations -35
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ThThe following table gives a summary of replaceable column 
(default) specifications for the basic column templates.  
Three Phase Distillation Template
If you select the Three Phase Distillation template, HYSYS 
creates a Column based on a three phase column model. 
Templates Vapour Draw Distillate Draw Reflux Ratio
Reboiled Absorber X
Refluxed Absorber
Total Condenser X
Partial Condenser X X
Distillation
Total Condenser X X
Partial Condenser X X X
 Figure 2.15
The same standard column types exist for a three phase 
system that are available for the “normal” two phase 
(binary) systems.-35
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-36 Column Installation
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ThUsing the Three Phase Column Input Expert, the initial property 
view allows you to select from the following options:
• Distillation
• Refluxed Absorber
• Reboiled Absorber
• Absorber
Each choice builds the appropriate column based on their 
respective standard (two phase) system templates.
If the Input Expert is turned off, installing a Three Phase column 
template opens a default Column property view for a Distillation 
type column equipped with a Reboiler and Condenser.
The key difference between using the standard column 
templates and their three phase counterparts lies in the solver 
that is used. The default solver for three phase columns is the 
“Sparse Continuation” solver which is an advanced solver 
designed to handle three phase, non ideal chemical systems, 
that other solvers cannot.
When using the Three Phase Column Input Expert some 
additional specifications can be required when compared with 
the standard (binary system) column setups.
Clicking the Side Ops button on the final page of the Three 
Phase Column Input Expert opens the Side Operations Input 
Expert wizard, which guides you through the process of adding a 
side operation to your column.
 Figure 2.16
It requires some expertise to 
set up, initialize, and solve 
three phase distillation 
problems. Additional modeling 
software applications such as 
DISTIL, use residue curve maps 
and distillation region diagrams 
to determine feasible designs, 
and can greatly assist in the 
initial design work. Contact 
your local AspenTech 
representative for details. -36
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Column Operations -37
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ThColumn Property View
The column property view is sectioned into tabs containing 
pages with information pertaining to the column. The column 
property view is accessible from the main flowsheet or Column 
subflowsheet. 
The column property view is used to define specifications, 
provide estimates, monitor convergence, view stage-by-stage 
and product stream summaries, add pump-arounds and side-
strippers, specify dynamic parameters and define other Column 
parameters such as convergence tolerances, and attach 
reactions to column stages.
The column property view is essentially the same when 
accessed from the main flowsheet or Column subflowsheet. 
However, there are some differences:
• The Connections page in the main flowsheet column 
property view displays and allows you to change all 
product and feed stream connections. In addition, you 
can specify the number of stages and condenser type.
• The Connections page in the subflowsheet Column 
property view (Column Runner) allows you to change the 
product and feed stream connections, and gives more 
flexibility in defining new streams.
• In the main flowsheet Column property view, the 
Flowsheet Variables and Flowsheet Setup pages allow 
you to specify the transfer basis for stream connections, 
and permit you to view selected column variables.    
In the Column subflowsheet, the column property view is 
also known as the Column Runner, and can be accessed by 
clicking the Column Runner icon.
In order to make changes or additions to the Column in the 
main simulation environment, the Solver should be active. 
Otherwise HYSYS cannot register your changes.
Column Runner icon-37
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-38 Column Property View
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ThColumn Convergence
The Run and Reset buttons are used to start the convergence 
algorithm and reset the Column, respectively. HYSYS first 
performs iterations toward convergence of the inner and outer 
loops (Equilibrium and Heat/Spec Errors), and then checks the 
individual specification tolerances.
The Monitor page displays a summary of the convergence 
procedure for the Equilibrium and Heat/Spec Errors. An example 
of a converged solution is shown in the following figure:
A summary of each of the tabs in the Column property view are 
in the following sections.
Design Tab
The following sections detail information regarding the Column 
property view pages. All pages are common to both the Main 
Column property view and the Column Runner, unless stated 
otherwise.
 Figure 2.17
Column Runner is another name for the subflowsheet 
Column property view.
Refer to the section on 
the Specification 
Tolerances for Solver 
for more information.-38
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Column Operations -39
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ThConnections page (Main Flowsheet)
The main flowsheet Connections page allows you to specify the 
name and location of feed streams, the number of stages in the 
tray section, the stage numbering scheme, condenser type, 
names of the Column product streams, and Condenser/Reboiler 
energy streams. 
The streams shown in this property view reside in the parent or 
main flowsheet; they do not include Column subflowsheet 
streams, such as the Reflux or Boilup. In other words, only feed 
and product streams (material and energy) appear on this page.
 Figure 2.18
If you have modified the Column Template (for example if 
you added an additional Tray Section), the Connections page 
appears differently than what is shown in Figure 2.18.-39
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-40 Column Property View
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ThWhen the column has complex connections, the Connections 
page changes to the property view shown in the figure below. 
You can also split the feed streams by selecting the Split 
checkbox associated to the stream.
Click the Edit Trays button to open the Tray Section Details 
property view. You can edit the number of trays in the column, 
and add or delete trays after or before the tray number of your 
choice in this property view.
 Figure 2.19
Figure 2.19 is an example of the Connections page for a 
Stripper Crude.
 Figure 2.20-40
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Column Operations -41
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ThConnections page (Column Runner)
The Connections page displayed in the Column Runner (inside 
the Column subflowsheet) appears as shown in the following 
figure. 
All feed and energy streams, as well as the associated stage, 
appear in the left portion of the Connections page. Liquid, 
vapour, and water product streams and locations appear on the 
right side of the page.
 Figure 2.21
If you specify a new stream name in any of the cells, this 
creates the stream inside the Column. This new stream is not 
automatically transferred into the main flowsheet.
You can connect or disconnect streams from the Connections 
page, as well as change the stream location.-41
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-42 Column Property View
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ThMonitor Page
The Monitor page is primarily used for editing specifications, 
monitoring Column convergence, and viewing Column profile 
plots. An input summary, and a property view of the initial 
estimates can also be accessed from this page.
 Figure 2.22
HYSYS displays the iteration number, step size, and 
Equilibrium and Heat/Spec errors in this area during 
the iteration process.
Profiles are where 
plots of column 
temperatures, flows, 
and pressures appear 
during convergence.
The Current checkbox 
shows the current 
specs that are being 
used in the column 
solution. You cannot 
select or clear this 
checkbox.
Specification types, 
the value of each 
specification, the 
current calculated 
value and the 
weighted error appear 
here.-42
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Column Operations -43
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ThOptional Checks Group
In the Optional Checks group, you find the following two 
buttons:
Profile Group
During the column calculations, a profile of temperature, 
pressure or flow appears, and is updated as the solution 
progresses. Select the appropriate radio button to display the 
desired variable versus tray number profile.
Specifications Group
Each specification, along with its specified value, current value, 
weighted error, and status is shown in the Specifications group. 
You can change a specified value by typing directly in the 
associated Specified Value cell. Specified values can also be 
viewed and changed on the Specs and Specs Summary pages. 
Any changes made in one location are reflected across all 
locations. 
Button Function
Input 
Summary 
Provides a column input summary in the Trace Window. 
The summary lists vital tower information including the 
number of trays, the attached fluid package, attached 
streams, and specifications.
You can click the Input Summary button after you make a 
change to any of the column parameters to view an 
updated input summary. The newly defined column 
configuration appears.
View Initial 
Estimates
Opens the Summary page of the Column property view, 
and displays the initial temperature and flow estimates for 
the column. You can then use the values generated by 
HYSYS to enter estimates on the Estimates page. 
These estimates are generated by performing one iteration 
using the current column configuration. If a specification for 
flow or temperature has been provided, it is honoured in 
the displayed estimates.
Refer to Section 1.3 - 
Object Status & Trace 
Windows in the HYSYS 
User Guide for details 
concerning the Trace 
Window.
Refer to Section  - 
Column Specification 
Types for a description of 
the available specification 
types.-43
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-44 Column Property View
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ThDouble-clicking on a cell within the row for any listed 
specification opens its property view. In this property view, you 
can define all the information associated with a particular 
specification. Each specification property view has three tabs:
• Parameters
• Summary
• Spec Type
This property view can also be accessed from both the Specs 
and Specs Summary pages. 
Spec Status Checkboxes
The status of listed specifications are one of the following types:
New specifications can also be added via the Specs page.
 Figure 2.23
Status Description
Active The active specification is one that the convergence 
algorithm is trying to meet. An active specification always 
serves as an initial estimate (when the Active checkbox is 
selected, HYSYS automatically selects the Estimate and 
Current checkboxes). An active specification always 
exhausts one degree of freedom.
An Active specification is one which the convergence 
algorithm is trying to meet initially. An Active specification 
has the Estimate checkbox selected also.
Estimate An Estimate is considered an Inactive specification because 
the convergence algorithm is not trying to satisfy it. To use 
a specification as an estimate only, clear the Active 
checkbox. The value then serves only as an initial estimate 
for the convergence algorithm. An estimate does not 
exhaust an available degree of freedom.
An Estimate is used as an initial “guess” for the 
convergence algorithm, and is considered to be an Inactive 
specification.
Further details are 
outlined in the section 
on the Specification 
Property View.-44
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Column Operations -45
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ThThe degrees of freedom value appears in the Degrees of 
Freedom field on the Monitor page. When you make a 
specification active, the degrees of freedom is decreased by 
one. Conversely, when you deactivate a specification, the 
degrees of freedom is increased by one. You can start column 
calculations when there are zero degrees of freedom.
Variables such as the duty of the reboiler stream, which is 
specified in the Workbook, or feed streams that are not 
completely known can offset the current degrees of freedom. If 
you feel that the number of active specifications is appropriate 
for the current configuration, yet the degrees of freedom is not 
zero, check the conditions of the attached streams (material and 
energy).You must provide as many specifications as there are 
available degrees of freedom. For a simple Absorber there are 
no available degrees of freedom, therefore no specifications are 
required. Distillation columns with a partial condenser have 
three available degrees of freedom.
Current This checkbox shows the current specs being used by the 
column solution. When the Active checkbox is selected, 
the Current checkbox is automatically selected. You 
cannot alter this checkbox.
When Alternate specs are used and an existing hard to 
solve spec has been replaced with an Alternate spec, this 
checkbox shows you the current specs used to solve the 
column.
A Current specification is one which is currently being used 
in the column solution.
Completely 
Inactive 
To disregard the value of a specification entirely during 
convergence, clear both the Active and Estimate 
checkboxes. By ignoring a specification rather than deleting 
it, you are always able to use it later if required. The 
current value appears for each specification, regardless of 
its status. An Inactive specification is therefore ideal when 
you want to monitor a key variable without including it as 
an estimate or specification.
A Completely Inactive specification is ignored completely by 
the convergence algorithm, but can be made Active or an 
Estimate at a later time.
Status Description-45
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-46 Column Property View
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ThSpecification Group Buttons
The four buttons which align the bottom of the Specifications 
group allow you to manipulate the list of specs. The table below 
describes the four buttons. 
Specs Page
Adding and changing Column specifications is straightforward. If 
you have created a Column based on one of the templates, 
HYSYS already has default specifications in place. The type of 
default specification depends on which of the templates you 
have chosen.
Button Action
View Move to one of the specification cells and click the View 
button to display its property view. You can then make any 
necessary changes to the specification. 
To change the value of a specification only, move to the 
Specified Value cell for the specification you want to 
change, and type in the new value.
You can also double-click in a specification cell to open its 
property view.
Add Spec Opens the Column Specifications menu list, from which you 
can select one or multiple (by holding the CTRL key while 
selecting) specifications, and then click the Add Spec(s) 
button. 
The property view for each new spec is shown and its name 
is added to the list of existing specifications. 
Update 
Inactive
Updates the specified value of each inactive specification 
with its current value.
Group Active Arranges all active specifications together at the top of the 
specifications list.
The active specification values are used as initial estimates 
when the column initially starts to solve.
Refer to the section on 
the Specification 
Property View for more 
details.
Refer to Section  - 
Column Specification 
Types for a description 
of the available 
specification types.
Refer to the Default 
Replaceable 
Specifications in 
Section  - Templates 
for more information.-46
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Column Operations -47
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ThColumn Specifications Group
The following buttons are available:
From the Default Basis drop-down list, you can choose the basis 
for the new specifications to be Molar, Mass or Volume.
 Figure 2.24
Button Action
View Opens the property view for the highlighted specification. 
Alternatively, you can object inspect a spec name and select 
View from the menu. 
Refer to the section on the Specification Property View for 
more details.
Add Opens the Add Specs property view, from which you can select 
one or multiple (by holding the CTRL key while selecting) 
specifications, and then click the Add Spec(s) button. 
The property view for each new spec is shown, and its name is 
added to the list of existing specifications. 
Refer to Section  - Column Specification Types for a 
description of the available specification types.
Delete Removes the highlighted specification from the list.
Add Specs property view-47
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-48 Column Property View
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ThThe Update Specs from Dynamics button replaces the specified 
value of each specification with the current value (lined out 
value) obtained from Dynamic mode.
Specification Property View
Figure 2.25 is a typical property view of a specification. In this 
property view, you can define all the information associated with 
a particular specification. Each specification property view has 
three tabs:
• Parameters
• Summary
• Spec Type
This example shows a component recovery specification which 
requires the stage number, spec value, and phase type when a 
Target Type of Stage is chosen.
Specification information is shared between this property view, 
and the specification list on both the Monitor and Specs 
Summary pages. Altering information in one location 
automatically updates across all other locations. 
For example, you can enter the spec value in one location, and 
the change is reflected across all other locations.
 Figure 2.25
Specify the stage 
to which the 
specification 
applies.
Specify Liquid or 
Vapor phase for 
the specification.
Provide the name 
of the 
component(s) to 
which the 
specification 
applies.
Provide basic 
spec information 
on the 
Parameters tab.-48
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Column Operations -49
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ThThe Summary tab is used to specify tolerances, and define 
whether the specification is Active or simply an Estimate.
The Spec Type tab (as shown in Figure 2.26) can be used to 
define specifications as either Fixed/Ranged and Primary/
Alternate. By default, all specifications are initially defined as 
Fixed and Primary. Advanced solving options available in HYSYS 
allow the use of both Alternate and Ranged Spec types.
The following section further details the advanced solving 
options available in HYSYS.
Ranged and Alternate Specs
The reliability of any solution method depends on its ability to 
solve a wide group of problems. Some specs like purity, 
recovery, and cut point are hard to solve compared to a flow or 
reflux ratio spec. The use of Alternate and/or Ranged Specs can 
help to solve columns that fail due to difficult specifications.
 Figure 2.26
Specify the interval for use with a Ranged Spec Value.
Define as either a Fixed or 
Ranged Spec. A Ranged Spec 
allows the solver to meet a 
Spec over an interval 
(defined according to the 
Upper and Lower spec 
values).
Define as either a Primary or 
Alternate Spec. An Alternate 
Spec can replace another hard 
to solve spec in situations 
where the column is not 
converging.
If the Column solves on an Alternate or Ranged Spec, the 
status bar reads “Converged - Alternate Specs” highlighted 
in purple.-49
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-50 Column Property View
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ThConfiguration of these advanced solving options are made by 
selecting the Advanced Solving Options button located on the 
Solver page. The advanced solving options are only available for 
use with either the Hysim I/O or Modified I/O solving methods. 
Fixed/Ranged Specs
For a Fixed Spec, HYSYS attempts to solve for a specific value. 
For a Ranged Spec, the solver attempts to meet the specified 
value, but if the rest of the specifications are not solved after a 
set number of iterations, the spec is perturbed within the 
interval range provided for the spec until the column converges.
Any column specification can be specified over an interval. A 
Ranged Spec requires both lower and upper specification values 
to be entered. This option (when enabled), can help solve 
columns where some specifications can be varied over an 
interval to meet the rest of the specifications.
Primary/Alternate Specs
A Primary Spec must be met for the column solution to 
converge. An Alternate Spec can be used to replace an existing 
hard to solve specification during a column solution. The solver 
first attempts to meet an active Alternate spec value, but if the 
rest of the specifications are not solved after a minimum 
number of iterations, the active Alternate spec is replaced by an 
inactive Alternate spec. 
When the solver attempts to meet a Ranged spec, the Wt. 
Error becomes zero when the Current Value is within the 
Ranged interval (as shown on the Monitor page). 
When an existing spec is replaced by an alternate spec 
during a column solution, the Current checkbox is cleared for 
the original (not met) spec and is selected for the alternate 
spec.
The number of active Alternate specs must always equal the 
number of inactive Alternate specs.
Refer to Advanced 
Solving Options Button 
in Section  - 
Parameters Tab for 
further details.-50
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Column Operations -51
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ThThis option (when enabled), can help solve columns where some 
specifications can be ignored (enabling another) to meet the 
rest of the specifications and converge the column.
 Specification Tolerances for Solver
The Solver Tolerances feature allows you to specify individual 
tolerances for your Column specifications. In addition to HYSYS 
converging to a solution for the Heat/Spec and Equilibrium 
Errors, the individual specification tolerances must also be 
satisfied. HYSYS first performs iterations until the Heat/Spec 
(inner loop), and Equilibrium (outer loop) errors are within 
specified tolerances.
The Column specifications do not have individual tolerances 
during this initial iteration process; the specification errors are 
“lumped” into the Heat/Spec Error. Once the Heat/Spec and 
Equilibrium conditions are met, HYSYS proceeds to compare the 
error with the tolerance for each individual specification. If any 
of these tolerances are not met, HYSYS iterates through the 
Heat/Spec, and Equilibrium loops again to produce another 
converged solution. The specification errors and tolerances are 
again compared, and the process continues until both the inner/
outer loops and the specification criteria are met.
Specific Solver Tolerances can be provided for each individual 
specification. HYSYS calculates two kinds of errors for each 
specification:
• an absolute error 
• a weighted error
Both Ranged or Alternate Specs must be enabled and 
configured using the Advanced Solving Options Button 
located on the Solver page of the Parameters tab before they 
can be applied during a column solution.
When the Weighted and Absolute Errors are less than their 
respective tolerances, an Active specification has converged.
For more information, 
refer to Section  - 
Parameters Tab.-51
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-52 Column Property View
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ThThe absolute error is simply the absolute value of the difference 
between the calculated and specified values:
The Weighted Error is a function of a particular specification 
type. When a specification is active, the convergence algorithm 
is trying to meet the Weighted Tolerances (Absolute Tolerances 
are only used if no Weighted Tolerances are specified, or the 
weighted tolerances are not met). 
Therefore, both the weighted and absolute errors must be less 
than their respective tolerances for an active specification to 
converge. HYSYS provides default values for all specification 
tolerances, but any tolerance can be changed. For example, if 
you are dealing with ppm levels of crucial components, 
composition tolerances can be set tighter (smaller) than the 
other specification tolerances. If you delete any tolerances, 
HYSYS cannot apply the individual specification criteria to that 
specification, and Ignore appears in the tolerance input field.
The specification tolerance feature is simply an “extra” to permit 
you to work with individual specifications and change their 
tolerances if desired.
Specification Details Group
For a highlighted specification in the Column Specifications 
group, the following information appears:
• Spec Name
• Convergence Condition. If the weighted and absolute 
errors are within their tolerances, the specification has 
converged and Yes appears.
• Status. You can manipulate the Active and Use As 
Estimate checkboxes. 
• Dry Flow Basis. Draw specifications are calculated on a 
dry flow basis by selecting the Dry Flow Basis 
checkbox.
This option is only available for draw specifications. The 
checkbox is greyed out if it does not apply to the 
specification chosen.
Errorabsolute = |Calculated Value - Specified Value| (2.3)
Refer to the Spec Status 
Checkboxes for further 
details concerning the use 
of these checkboxes.-52
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Column Operations -53
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Th• Spec Type. You can select between Fixed/Ranged and 
Primary/Alternate specs. 
• Specified and Current Calculated Values.
• Weighted/Absolute Tolerance and Calculated Error.
Specs Summary Page
The Specs Summary page lists all Column specifications 
available along with relevant information. This specification 
information is shared with the Monitor page and Specs page. 
Altering information in one location automatically updates 
across all other locations. 
Subcooling Page
The Subcooling page allows you to specify subcooling for 
products coming off the condenser of your column. You can 
specify the condenser product temperature or the degrees to 
subcool. For columns without condensers, such as absorbers, 
You can edit any specification values (in the Column 
property view) shown in blue.
 Figure 2.27
You can edit any specification details shown in blue.
You can double-click in a specification cell to open its 
property view.
Refer to the section on 
the Ranged and 
Alternate Specs for 
more details.
Refer to the section on the 
Specification Property 
View for more details.-53
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-54 Column Property View
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Ththis page requires no additional information.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Parameters Tab
The Parameters tab shows the column calculation results, and is 
used to define some basic parameters for the Column solution. 
The Parameters tab consists of six pages:
• Profiles
• Estimates
• Efficiencies
• Solver
• 2/3 Phase
• Amines
Profiles Page
The Profiles page shows the column pressure profile, and 
provides estimates for the temperature, net liquid and net 
vapour flow for each stage of the column. You can specify tray 
estimates in the Temperature column, Net Liquid column and 
Net Vapour column, or view the values calculated by HYSYS.
The Subcooling page is not available for Liquid-Liquid 
Extractor.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.-54
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Column Operations -55
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ThThe graph in Figure 2.28 depicts the pressure profile across the 
column.
Use the radio buttons in the Flow Basis group to select the flow 
type you want displayed in the Net Liquid and Net Vapour 
columns. The Flow Basis group contains three radio buttons:
• Molar
• Mass
• Volume
The buttons in the Steady State Profiles group are defined as 
follows:
 Figure 2.28
At least one iteration must have occurred for HYSYS to 
convert between bases. In this way, values for the 
compositions on each tray are available.
Button Function
Update from 
Solution
Transfers the current values that HYSYS has calculated for 
the trays into the appropriate cells. Estimates that have 
been Locked (displayed in blue) are not updated. The 
Column Profiles page on the Performance tab allows you to 
view all the current values.
Clear Deletes values for the selected tray.-55
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-56 Column Property View
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ThAlthough the Profiles page is mainly used for steady state 
simulation, it does contain vital information for running a 
column in dynamics. One of the most important aspects of 
running a column in dynamics is the pressure profile. While a 
steady state column can run with zero pressure drop across a 
tray section, the dynamic column requires a pressure drop. In 
dynamics, an initial pressure profile is required before the 
column can run. This profile can be from the steady state model 
or can be added in dynamics. If a new tray section is created in 
Dynamic mode, the pressure profile can be obtained from the 
streams if not directly specified. In either case, the closer the 
initial pressure profile is to the one calculated while running in 
dynamics, the fewer problems you encounter.
Estimates Page
The Estimates page allows you to view and specify composition 
estimates. 
When you specify estimates on stages that are not adjacent to 
each other, HYSYS cannot interpolate values for intermediate 
stages until the solution algorithm begins.
Clear All 
Trays
Deletes values for all trays.
Lock Changes all red values (unlocked estimates, current values, 
interpolated values) to blue (locked), which means that 
they cannot be overwritten by current values when the 
Update from Solution button is clicked.
Unlock Changes all blue values (locked) to red (unlocked). 
Unlocked values are overwritten by current values when 
the Update from Solution button is clicked.
Stream 
Estimates
Displays the temperature, molar flow, and enthalpy of all 
streams attached to the column operation.
To see the initial estimates generated by HYSYS, click the 
View Initial Estimates button on the Monitor page.
Estimates are NOT required for column convergence.
Button Function-56
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Column Operations -57
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ThYou can specify tray by tray component composition estimates 
for the vapour phase or liquid phase. Each composition estimate 
is on a mole fraction basis, so values must be between 0 and 1.
HYSYS interpolates intermediate tray component values when 
you specify compositions for non-adjacent trays. The 
interpolation is on a log basis. Unlike the temperature 
estimates, the interpolation for the compositions does not wait 
for the algorithm to begin. Select either the Vap or Liq radio 
button in the Phase group to display the table for the vapour or 
liquid phase, respectively.
The Composition Estimates group has the following buttons:
 Figure 2.29
Button Action
Clear Tray Deletes all values, including user specified (blue) and 
HYSYS generated (red), for the selected tray.
HYSYS does not ask for confirmation before deleting 
estimates.
Clear All Trays Deletes all values for all trays.
HYSYS does not ask for confirmation before deleting 
estimates.
Update Transfers the current values which HYSYS has calculated 
for tray compositions into the appropriate cells. Estimates 
that have been locked (shown in blue) cannot be 
updated.-57
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-58 Column Property View
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ThEfficiencies Page
The Efficiencies page allows you to specify Column stage 
efficiencies on an overall or component-specific basis. 
Efficiencies for a single stage or a section of stages can easily be 
specified.
HYSYS uses a modified Murphree stage efficiency. All values are 
initially set to 1.0, which is consistent with the assumption of 
ideal equilibrium or theoretical stages. If this assumption is not 
valid for your column, you have the option of specifying the 
number of actual stages, and changing the efficiencies for one 
or more stages.
Restore Removes all HYSYS updated values from the table, and 
replaces them with your estimates and their 
corresponding interpolated values. Any cells that did not 
contain estimates or interpolated values are shown as 
. This button essentially reverses the effect of 
the Update button. 
If you had entered some estimate values, click the Unlock 
Estimates button, and click the Update button. All the 
values in the table appear in red. You can restore your 
estimated values by clicking the Restore button. 
Normalize 
Trays
Normalizes the values on a tray so that the total of the 
composition fractions equals 1. HYSYS ignores  
cells, and normalizes the compositions on a tray provided 
that there is at least one cell containing a value.
Lock Estimates Changes all red values (unlocked estimates, current 
values, interpolated values) to blue (locked), which 
means that they cannot be overwritten by current values 
when the Update button is clicked.
Unlock 
Estimates
Changes all blue values (locked) to red (unlocked). 
Unlocked values are overwritten by current values when 
the Update button is clicked.
Fractional efficiencies cannot be given for the condenser or 
reboiler stages, nor should they be set for feed or draw 
stages.
The functionality of this page is slightly different when 
working with the Amines Property Package.
Button Action
Refer to the section on 
Special Case - Amines 
Property Package for 
more information. -58
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Column Operations -59
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ThTo specify an efficiency to multiple cells, highlight the desired 
cells, enter a value in the Eff. Multi-Spec field, and click the 
Specify button.
The data table on the Efficiency page gives a stage-by-stage 
efficiency summary.      
Overall stage efficiencies can be specified by selecting the 
Overall radio button in the Efficiency Type group, and entering 
values in the appropriate cells.
Component-specific efficiencies can be specified by selecting the 
Component radio button, and entering values in the appropriate 
cells.
 Figure 2.30
The efficiencies are fractional.  In other words, an efficiency 
of 1.0 corresponds to 100% efficiency.-59
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-60 Column Property View
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ThSpecial Case - Amines Property Package
When solving a column for a case using the Amines Property 
Package, HYSYS always uses stage efficiencies for H2S and CO2 
component calculations. If these are not specified on the 
Efficiencies page of the Column property view, HYSYS calculates 
values based on the tray dimensions. Tray dimensions can be 
specified on the Amines page of the Parameters tab. If column 
dimensions are not specified, HYSYS uses its default tray values 
to determine the efficiency values.
If you specify values for the CO2 and H2S efficiencies, these are 
the values that HYSYS uses to solve the column. If you want to 
solve the column again using efficiencies generated by HYSYS, 
click the Reset H2S, CO2 button, which is available on the 
Efficiencies page. Run the column again, and HYSYS calculates 
and displays the new values for the efficiencies.
Select the Transpose checkbox to change the component 
efficiency matrix so that the rows list components and the 
columns list the stages. 
The Reset H2S, CO2 button, and the Transpose checkbox are 
available only if the Efficiency Type is set to Component.
For more information on 
the Amines Property 
Packages, refer to 
Appendix C - Amines 
Property Package of the 
HYSYS Simulation 
Basis guide.-60
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Column Operations -61
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ThSolver Page
You can manipulate how the column solves the column variables 
on the Solver page. 
Solving Options Group
Specify your preferences for the column solving behaviour in the 
Solving Options group.
 Figure 2.31
The Solving Method Group, Acceleration Group, and Damping 
Group will have different information displayed according to 
the options selected within the group. 
 Figure 2.32-61
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ThMaximum Number of Iterations
The Column convergence process terminates if the maximum 
number of iterations is reached. The default value is 10000, and 
applies to the outer iterations. If you are using Newton's 
method, and the inner loop does not converge within 50 
iterations, the convergence process terminates.
Equilibrium and Heat/Spec Tolerances
Convergence tolerances are pre-set to very tight values, thus 
ensuring that regardless of the starting estimates (if provided) 
for column temperatures, flow rates, and compositions, HYSYS 
always converges to the same solution. However, you have the 
option of changing these two values if you want. Default values 
are:
• Inner Loop. Heat and Spec Error: 5.000e-04
• Outer Loop. Equilibrium Error: 1.000e-05
Because the default values are already very small, you should 
use caution in making them any smaller. You should not make 
these tolerances looser (larger) for preliminary work to reduce 
computer time. The time savings are usually minor, if any. Also, 
if the column is in a recycle or adjust loop, this could cause 
difficulty for the loop convergence.
Equilibrium Error
The value of the equilibrium error printed during the column 
iterations represents the error in the calculated vapour phase 
mole fractions. The error over each stage is calculated as one 
minus the sum of the component vapour phase mole fractions. 
This value is then squared; the total equilibrium error is the sum 
of the squared values. The total equilibrium error must be less 
than 0.00001 to be considered a converged column.-62
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Column Operations -63
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ThHeat and Spec Error
The heat and specification error is the sum of the absolute 
values of the heat error and the specification error, summed 
over each stage in the tower.
This total value is divided by the number of inner loop 
equations. The heat error contribution is the heat flow 
imbalance on each tray divided by the total average heat flow 
through the stage.
The specification error contribution is the sum of each individual 
specification error divided by an appropriate normalization 
factor.
• For component(s) flow, the normalization factor is the 
actual component(s) flow.
• For composition, it is the actual mole fraction.
• For vapour pressure and temperature, it is a value of 
5000.
• And so forth. 
The total sum of heat and spec errors must be less than 0.0005 
to be considered a converged column.
The allowed equilibrium error and heat and spec error are 
tighter than in most programs, but this is necessary to avoid 
meta-stable solutions, and to ensure satisfactory column heat 
and material balances.
Save Solution as Initial Estimate
This option is on by default, and it saves converged solutions as 
estimates for the next solution.-63
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-64 Column Property View
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ThSuper Critical Handling Model
Supercritical phase behaviour occurs when one or more Column 
stages are operating above the critical point of one or more 
components. During the convergence process, supercritical 
behaviour can be encountered on one or more stages in the 
Column. If HYSYS encounters supercritical phase behaviour, 
appropriate messages appear in the Trace Window.
HYSYS cannot use the equation of state or activity model in the 
supercritical range, so an alternate method must be used. You 
can specify which method you want HYSYS to use to model the 
phase behaviour. There are three choices for supercritical 
calculations:
Trace Level
The Trace Level defines the level of detail for messages 
displayed in the Trace Window, and can be set to Low, Medium, 
or High. The default is Low.
Model Description
Simple K The default method. HYSYS calculates K-values for the 
components based on the vapour pressure model being 
used. Using this method, the K-values which are 
calculated are ideal K-values.
Decrease 
Pressure
When supercritical conditions are encountered, HYSYS 
reduces the pressure on all trays by an internally 
determined factor, which can be seen in the Trace 
Window when the Verbose option is used. This factor is 
gradually decreased until supercritical conditions no 
longer exist on any tray, at which point, the pressure in 
the column is gradually increased to your specified 
pressure. If supercritical conditions are encountered 
during the pressure increase, the pressure is once 
again reduced and the process is repeated. 
Adjacent Tray When supercritical conditions are encountered on a 
tray, HYSYS searches for the closest tray above which 
does not have supercritical behaviour. The non-
supercritical conditions are substituted in the phase 
calculations for the tray with supercritical conditions.
Refer to Section 1.3 - 
Object Status & Trace 
Windows in the HYSYS 
User Guide for details on 
the Trace Window.-64
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Column Operations -65
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ThInitialize from Ideal K’s
When this checkbox is selected, HYSYS initializes its column 
solution using ideal K values which are calculated from vapour 
pressure correlations. The ideal K-value option, which is also 
used by HYSIM, increases the compatibility between HYSIM and 
HYSYS.
By default, the Initialize from Ideal K's checkbox is cleared. 
HYSYS uses specified composition estimates or generates 
estimates to rigorously calculate K-values.
Two Liquids Check Based on
This option allows you to specify a check for two liquid phases in 
the column. The check is based on one of the following criteria:
• No 2 Liq Check. Disables the two liquid check.
• Tray Liquid Fluid. The calculation is based on the 
composition of the liquid in the column.
• Tray Total Fluid. The calculation is based on the overall 
composition of the fluid in the column.
Tighten Water Tolerance
When this checkbox is selected, HYSYS increases the 
contribution of the water balance error to the overall balance 
error in order to solve columns with water more accurately. The 
default setting for this checkbox is cleared.-65
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ThSolving Method Group
The Solving Method drop-down list allows you to select the 
column solution method. 
The display field, which appears below the drop-down list, 
provides explanations for each method, and is restated here:
Inside-Out
With the “inside-out” based algorithms, simple equilibrium and 
enthalpy models are used in the inner loop to solve the overall 
component and heat balances as well as any specifications. The 
outer loop updates the simple thermodynamic models with 
rigorous model calculations.
 Figure 2.33
Method Explanation
HYSIM Inside-
Out
General purpose method, which is good for most 
problems.
Modified HYSIM 
Inside-Out 
General purpose method, which allows mixer, tee, and 
heat exchangers inside the column subflowsheet.
Only a simple Heat Exchanger Model (Calculated from 
Column) is available in the Column subflowsheet. The 
Simple Rating, End-Point, and Weighted models are 
not available.
Newton Raphson 
Inside-Out 
General purpose method, which allows liquid-phase 
kinetic reactions inside the Column subflowsheet.
Sparse 
Continuation 
Solver
An equation based solver. It supports two liquid phases 
on the trays, and its main use is for solving highly non-
ideal chemical systems and reactive distillation.
Simultaneous 
Correction 
Simultaneous method using dogleg methods. Good for 
chemical systems. This method also supports reactive 
distillation.
OLI Solver Only used to calculate the column unit operation in an 
electrolyte system.-66
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ThSparse Continuation Solver Control Panel
When the Sparse Continuation Solver is selected, the Control 
button becomes available. This button brings up the Sparse 
Continuation Solver Control Panel. This panel gives you the 
following options: 
• Liquid Fugacity Model
- Temp Only
- Temp and Composition
- Property Package
• Vapour Fugacity Model
- Temp Only
- Temp and Composition
- Property Package
• Liquid Enthalpy Model
- Simple Liquid Model
- Property Package
• Vapour Enthalpy Model
- Simple Liquid Model
- Property Package
Select the Chemical Defaults radio button in the Phase 
Fugacity Models group to use the following default settings: 
• Liquid Fugacity Model  - Property Package
• Vapour Fugacity Model - Temp and Composition
• Liquid Enthalpy Model - Simple Liquid Model
• Vapour Enthalpy Model - Simple Vapour Model
Select the Hydrocarbon Defaults radio button in the Phase 
Fugacity Models group to use the following default settings:
• Liquid Fugacity Model - Temp and Composition
• Vapour Fugacity Model - Temp Only
• Liquid Enthalpy Model - Simple Liquid Model
• Vapour Enthalpy Model - Simple Vapour Model
Note: Whenever you modify any of the default settings the User 
Specified radio button becomes active.
General Features of the Solving Methods
The following table displays the general features of all the -67
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-68 Column Property View
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ThHYSYS column solving methods.
HYSIM 
I/O
Modified 
HYSIM I/O
Newton 
Raphson I/O
Sparse 
Continuation
Simultaneous 
Correction
OLI
Component 
Efficiency 
Handling
Yes Yes No Yes No Yes
Total 
Efficiency 
Handling
Yes Yes No Yes No Yes
Additional 
Side Draw
Yes Yes Yes Yes Yes Yes
Vapour 
Bypass
Yes Yes No Yes No No
Pump 
Arounds
Yes Yes No Yes No Yes
Side Stripper Yes Yes No Yes No No
Side Rectifier Yes Yes No Yes No No
Mixer & Tee 
in Sub-
flowsheet
No Yes No No No No
Three Phase Yes 
(water 
draw)
Yes (water 
draw)
No Yes No Yes
Chemical 
(reactive)
No No Yes Yes Yes Inter
nal 
reacti
ons-68
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Column Operations -69
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ThAcceleration Group
When selected, the Accelerate K value & H Model 
Parameters checkbox displays two fields, which relate to an 
acceleration program called the Dominant Eigenvalue Method 
(DEM). 
The DEM is a numerical solution program, which accelerates 
convergence of the simple model K values and enthalpy 
parameters. It is similar to the Wegstein accelerator, with the 
main difference being that the DEM considers all interactions 
between the variables being accelerated. The DEM is applied 
independently to each stage of the column.     
The listed DEM parameters include:
 Figure 2.34
By default, the Accelerate K value & H Model Parameters 
checkbox is cleared.
Use the acceleration option if you find that the equilibrium 
error is decreasing slowly during convergence. This should 
help to speed up convergence. Notice that the Accelerate K 
value & H Model Parameters checkbox should NOT be 
selected for AZEOTROPIC columns, as convergence tends to 
be impeded.
Parameter Description
Acceleration 
Mode
Select either Conservative or Aggressive. With the 
Conservative approach, smaller steps are taken in the 
iterative procedure, thus decreasing the chance of a bad 
step.
Maximum 
Iterations 
Queued 
Allows you to choose the number of data points from 
previous iterations that the accelerator program uses to 
obtain a solution.-69
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-70 Column Property View
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ThDamping Group
Choose the Damping method by selecting either the Fixed or 
Adaptive radio button.
Fixed Damping
If you select the Fixed radio button, you can specify the 
damping factor. The damping factor controls the step size used 
in the outer loop when updating the simple thermodynamic 
models used in the inner loop. For the vast majority of 
hydrocarbon-oriented towers, the default value of 1.0 is 
appropriate, which permits a full adjustment step. However, 
should you encounter a tower where the heat and specification 
errors become quite small, but the equilibrium errors diverge or 
oscillate and converge very slowly, try reducing the damping 
factor to a value between 0.3 and 0.9. Alternatively, you could 
enable Adaptive Damping, allowing HYSYS to automatically 
adjust this factor.    
There are certain types of columns, which definitely require a 
special damping factor. 
Use the following table as a guideline in setting up the initial 
value. 
 Figure 2.35
Changing the damping factor has an effect on problems 
where the heat and spec error does not converge.
Type of Column Damping Factor
All hydrocarbon columns from demethanizers to 
debutanizers to crude distillation units
1.0
Non-hydrocarbon columns including air separation, 
nitrogen rejection
1.0-70
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ThAs shown in the table above, an azeotropic column requires the 
azeotrope checkbox to be enabled. There are two ways to 
indicate to HYSYS that you are simulating an azeotropic column:
• Enter a negative damping factor, and HYSYS 
automatically selects the Azeotropic checkbox. 
• Enter a positive value for the damping factor, and select 
the Azeotropic checkbox.
Most petrochemical columns including C2= and C3= 
splitters, BTX columns
1.0
Amines absorber 1.0
Amines regenerator, TEG strippers, sour water 
strippers
0.25 to 0.50
Highly non-ideal chemical columns without azeotropes 0.25 to 0.50
Highly non-ideal chemical columns with azeotropes 0.50 to -1.0*
The Azeotropic checkbox on the Solver page of the 
Parameters tab must be selected for an azeotropic column to 
converge.
The absolute value of the damping factor is always 
displayed.
Type of Column Damping Factor-71
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-72 Column Property View
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ThAdaptive Damping
If you select the Adaptive radio button, the Damping matrix 
displays three fields. HYSYS updates the damping factor as the 
column solution is calculated, depending on the Damping Period 
and convergence behaviour.
Initialization Algorithm Radio Buttons
There are two types of method for the initialization algorithm 
calculation:
• Standard Initialization radio button uses the tradition 
initialization algorithm in Hysys. 
• Program Generates Estimations radio button uses a 
new functionality that handles the cases where the 
traditional initialization does not.
Damping Period Description
Initial Damping 
Factor
Specifies the starting point for adaptive damping.
Adaptive 
Damping Period
The default Adaptive Damping Period is ten. In this 
case, after the tenth iteration, HYSYS looks at the last 
ten errors to see how many times the error increased 
rather than decreased. If the error increased more 
than the acceptable tolerance, this is an indication that 
the convergence is likely cycling, and the current 
damping factor is then multiplied by 0.7. Every ten 
iterations, the same analysis is done to see if the 
damping factor should be further decreased. 
Alternatively, if the error increased only once in the 
last period, the damping factor is increased to allow for 
quicker convergence.
Reset Initial 
Damping Factor
If this checkbox is selected, the current damping factor 
is used the next time the column is solved. 
If this checkbox is cleared, the damping factor before 
adaptive damping was applied is used.
 Figure 2.36-72
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Column Operations -73
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ThThe following list situations when the Program Generates 
Estimations (PGE) initialization method is used:
• The PGE initialization handles systems with more than 25 
components while the standard initialization does not 
handle systems with more than 25 components without 
the user’s initial estimation. 
• When column does not converge with the standard 
initialization method (default), switching to PEG may 
converge the column. The new algorithm eliminates the 
discrepancy in the temperature and component 
estimates, which may exist in standard initialization.
Initial Estimate Generator Parameters
You can enable the initial estimate generator (IEG) by selecting 
the Dynamic Integration for IEG checkbox. The IEG then 
performs iterative flash calculations (NRSolver, PV, and PH) to 
provide initial estimates for the temperature and composition 
profiles. No user estimates are required when the Dynamic 
Integration for IEG checkbox is selected.
Click the Dynamic Estimates Integrator button, and the Col 
Dynamic Estimates property view appears as shown in the 
figure below. 
 Figure 2.37-73
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-74 Column Property View
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ThCol Dynamic Estimates Property View
The Col Dynamic Estimates property view allows you to further 
define the dynamic estimates parameters.
You can set parameters for the time period over which the 
dynamic estimates are calculated, as well as set the calculation 
tolerance. A selected Active checkbox indicates that the 
Dynamic Integration for IEG is on. Select either the Adiabatic or 
Isothermal radio button to set the dynamic initialization flash 
type. 
If you want to generate the dynamic estimates without running 
the column, you can do so from this property view by clicking 
the Start button. If you want to stop calculations before the 
specified time has elapsed, click the Stop button. You do not 
have to manually click the Start button to generate the 
estimates; if the Dynamic Integration for IEG option is active, 
HYSYS generates them automatically whenever the column is 
running.
The Shortcut Mode checkbox allows you to bypass this step once 
a set of estimates is generated, that is, once the column has 
converged.
 Figure 2.38
If you are running simulation with an iterative solving 
procedure where the column has to be calculated several 
times, it is a good idea to select this option to save on 
calculation time.-74
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Column Operations -75
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ThAdvanced Solving Options Button
When you click the Advanced Solving Options button, the 
Advanced Solving Options property view appears. 
On the Advanced Solving Options property view, each solving 
option (for exmple, Alternate, Ranged, and Autoreset) has a 
solving priority and also a checkbox option. To use a particular 
solving option, you have to select the corresponding checkbox. 
You must also specify the priority of the solving method. This is 
the order in which the solving options are executed (either first, 
second or third).
Advanced solving options cannot be used until the minimum 
number of iterations are met. If the column is not solved after 
the minimum number of iterations, the solver switches to an 
advanced solving option according to the solving priority. This 
process is repeated until all the solving options have been 
attempted or the column converges.
 Figure 2.39
All the Alternate active specs 
can be replaced on an 
individual spec basis or all 
specs simultaneously. The 
alternative (active) spec 
with the larger error is 
replaced with an alternative 
inactive spec with minimum 
error.
The “use” checkboxes must 
be selected in order to 
enable a particular option.
These checkboxes are only 
enabled if the corresponding 
spec type exists. 
The order in 
which the solving 
options are 
executed is based 
on the priority.
If the Column converges on an Alternate or Ranged Spec, the 
status bar reads “Converged - Alternate Specs” highlighted 
in purple.-75
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-76 Column Property View
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Th2/3 Phase Page
The 2/3 Phase page is relevant only when you are working with 
three-phase distillation. On this page, you can check for the 
presence of two liquid phases on each stage of your column. 
The Liquid Phase Detection table lists the liquid molar flow rates 
on each tray of the tray section, including the reboiler and the 
condenser. 
In order for HYSYS to check for two liquid phases on any given 
stage, select the checkbox in the Check column. If a second 
liquid phase is calculated, this is indicated in the Detected 
column, and by a calculated flowrate value in the L2Rate 
When a column is in recycle, by default, the solver switches 
to the original set of specs after each recycle iteration or the 
next time the column solves.
 Figure 2.40
This page is not available for Liquid-Liquid Extractor.-76
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Column Operations -77
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Thcolumn. The buttons in the Liquid Phase Detection group serve 
as aids in selecting and de-selecting the trays you want to 
check.
The 2nd Liquid Type group allows you to specify the type of 
calculation HYSYS performs when checking for a second liquid 
phase. When the Pure radio button is selected, HYSYS checks 
only for pure water as the second phase. This helps save 
calculation time when working with complex hydrocarbon 
systems. When you want a more rigorous calculation, select the 
Rigorous radio button. 
Auto Water Draws Button
The Auto Water Draws (AWD) option allows for the automatic 
adding and removing of total aqueous phase draws depending 
on the conditions in the converged column. 
AWD updating process is based on direct check of stage fluid 
phases. The direct check follows the Two Liquids Check Based on 
control criteria for detecting the aqueous phase. AWD mode is 
not available if No 2 Liq Check option is selected.
Checking for liquid phases in a three phase distillation tower 
greatly increases the solution time. Typically, checking the 
top few stages only, provides reasonable results.
By default, HYSYS selects Pure for all hydrocarbon, and 
Rigorous for all chemical based distillations. This default 
selection criteria is based on the type of fluid package used 
but you can always change it. 
The Auto Water Draws facility is available for IO and MIO 
solvers.
The Two Liquids Check Based on drop-down list is located in 
the Parameters tab of the Solver page in the Solving Options 
group.-77
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-78 Column Property View
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ThTo manipulate the AWD option, click the Auto Water Draws 
button to open the Auto Water Draws property view.
The Auto Water Draws property view contains the following 
objects:
The Auto Water Draws button is available in both column 
subflowsheet and main flowsheet.
 Figure 2.41
Object Description
On Select this checkbox to activate the Auto Water Draws 
mode.
Threshold The threshold value allows variation of the condition 
for 2nd liquid phase. The default value in this cell is 
0.001 (same as for Two Liquids Check based on 
control).
If you delete the value in this cell, the threshold is set 
to minimum possible value.
Keep draws If this checkbox is selected, the added draws are not 
removed.
Preserve 
estimates
If this checkbox is selected, the converged values are 
preserved as estimates for the next column run.
Reset If this checkbox is selected, the column Reset option is 
performed before each column run.
Strategy There are three options of strategy to select from in 
the Strategy group:
• All. All required changes in water draw 
configuration are done simultaneously.
• From Top.Updates on the topmost stage from 
required is performed.
• From Bottom. Updates on the bottommost stage 
from required is performed.
The All option results typically in multiple water draws 
with small flows, and the From Top or From Bottom 
option results typically in fewer water draws.
To AWD All existing water draws are converted to AWDs. -78
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Column Operations -79
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ThTwo more columns are added in the table on the 2/3 Phase page 
when in Auto Water Draws mode. These two columns are called 
AWD and No AWD
• Set AWD mode for attached water draw by selecting the 
checkboxes under the AWD column.
• If the checkbox in the No AWD column is selected, no 
AWD will be attached to corresponding stage.
Amines Page
The Amines page appears on the Parameters tab only when 
working with the Amines Property Package.
There are two groups on the Amine page:
• Tray Section Dimensions for Amine Package
• Approach to Equilibrium Results
Tray Section Dimensions for Amine Package
When solving the column using the Amines package, HYSYS 
always takes into account the tray efficiencies, which can either 
be user-specified, on the Efficiencies page, or calculated by 
HYSYS. Calculated efficiency values are based on the tray 
dimensions specified. The Amines page lists the tray section 
dimensions of your column, where you can specify these values 
that are used to determine the tray efficiencies in the Tray 
Section Dimensions for Amine Package group. 
From AWD Converts all AWDs to regular draws.
Restore Restores the last successful (in other words, column 
equation were solved) AWD configuration.
Delete Deletes all AWDs.
The Amines Property Package is an optional property 
package that must be purchased in addition to the base 
version of HYSYS.
Object Description
For more information on 
the Amines Property 
Package, refer to the 
Appendix C - Amines 
Property Package in 
the HYSYS Simulation 
Basis guide.-79
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-80 Column Property View
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ThThe list includes:
• Tray Section
• Weir Height
• Weir Length
• Tray Volume
• Tray Diameter
If tray dimensions are not specified, HYSYS uses the default tray 
dimensions to determine the efficiency values.
Approach to Equilibrium Results
Approach to Equilibrium values are used for the design, 
operation, troubleshooting, and de-bottlenecking for the 
absorption and regeneration columns in an amine plant. When 
you are modeling an amine column in HYSYS, you can calculate 
the Approach to Equilibrium values after the column converges. 
With this capability, you can adjust the flowrate of amine to 
achieve a certain Approach to Equilibrium value recommended 
by literature or in-house experts for the amine column. The 
extension is compatible with all of the major amine and 
mixtures of amines (in other words, MEA, DEA, TEA, DGA, DIPA, 
MDEA, and any mixtures of these amines).
The Approach to Equilibrium extension calculates the Approach 
to Equilibrium value of rich amine from the bottom of the 
absorber column in two methods:
• Partial Pressure
• Amine Molar Loading
Method 1 Partial Pressure
In this method, the Approach to Equilibrium is defined as the 
partial pressure of the acid gas in the rich amine stream exiting 
the absorber relative to the partial pressure of the acid gas in 
the main feed gas stream entering the absorber. 
The extension can only be used on a pre-converged amine 
treating unit simulation with the Amine Property Package.-80
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Column Operations -81
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ThThe Approach to Equilibrium calculation are as follows:
The Approach to Equilibrium results based on H2S and CO2 are 
expressed in percentages. When both H2S and CO2 are present, 
the highest Approach to Equilibrium percentage is usually 
reported, although both values should be reported.
Amine Molar Loading
Amine Molar Loading is defined as the loading of the rich amine 
solution leaving the absorber divided by the equilibrium amine 
loading, assuming that the amine is at equilibrium with the feed 
gas and is at the same temperature as the rich amine leaving 
the absorber. The temperature of the rich amine and the amine 
in equilibrium with the feed gas are the same. The result is 
expressed as a percentage as follows:
In general, the Approach to Equilibrium value calculated by the 
Partial Pressure method is greater than the one calculated by 
the Amine Molar Loading method.
(2.4)
(2.5)
(2.6)
H2S 100%
ppH2Srich amine exiting the absorber
ppH2Sfeed gas entering the absorber
-----------------------------------------------------------------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞
⋅=
CO2 100%
ppCO2rich amine exiting the absorber
ppCO2feed gas entering the absorber
------------------------------------------------------------------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞
⋅=
Approach
to Equilibrium
100%
Rich amine loading
in mole AG
mole of amine⁄
Equilibrium loading
in mole AG
mole of amine⁄
--------------------------------------------------------------------------------
⎝ ⎠
⎜ ⎟
⎜ ⎟
⎜ ⎟
⎛ ⎞
⋅=-81
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-82 Column Property View
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ThSide Ops Tab
Side strippers, side rectifiers, pump arounds, and vapour 
bypasses can be added to the Column from this tab. To install 
any of these Side Operations, click the Side Ops Input Expert 
button or on the appropriate Side Ops page, click the Add 
button.
• If you are using the Side Ops Input Expert, a wizard 
guides you through the entire procedure of adding a side 
operation to your column.
• If you are using the Add button, complete the form which 
appears, and then click the Install button. 
Specifications that are created when you add a side 
operation are automatically added to the Monitor page 
and Specs page. 
For instance, when you add a side stripper, product draw 
and boilup ratio specs are added. As well, all appropriate 
operations are added; for example, with the side stripper 
(reboiled configuration), a side stripper tray section and 
reboiler are installed in the Column subflowsheet.
You can view or delete any Side Operation simply by positioning 
the cursor in the same line as the Operation, and clicking the 
View or Delete button. 
Side Strippers Page
You can install a reboiled or steam-stripped side stripper on this 
page. You must specify the number of stages, the liquid draw 
stage (from the Main Column), the vapour return stage (to the 
Main Column), and the product stream and flow rate (on a 
molar, mass or volume basis).
For the reboiled configuration, you must specify the boilup ratio, 
which is the ratio of the vapour to the liquid leaving the reboiler. 
If you are specifying Side Operations while in the Main 
simulation environment, make sure that the Solver is Active. 
Otherwise, HYSYS cannot register your changes.
The Side Ops tab is not available in the Liquid-Liquid 
Extractor.
Some solver methods do not allow side ops.Refer to the table in the 
section on the General 
Features of the 
Solving Methods for 
more information.-82
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Column Operations -83
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ThFor the steam-stripped configuration it is necessary to specify 
the steam feed. 
The property view of the side stripper is shown in the figure 
below.
When you click the Install button, a side stripper tray section is 
installed, as well as a reboiler if you selected the Reboiled 
configuration.
By default, the tray section is named SS1, the reboiler is named 
SS1_Reb, and the reboiler duty stream is named SS1_Energy. 
As you add additional Side strippers, the index increases (for 
example SS2, SS3, and so forth).
 Figure 2.42
To change the side stripper draw and return stages from the 
Column property view, the Solver must be Active in the Main 
simulation environment.-83
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-84 Column Property View
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ThSide Rectifiers Page
As with the side stripper, you must specify the number of 
stages, the liquid draw stage, and the vapour return stage.
The vapour and liquid product rates, as well as the reflux ratio 
are also required. These specifications are added to the Monitor 
page and Specs page of the Column property view.
When you install the side rectifier, a side rectifier tray section 
and partial condenser are added. By default, the tray section is 
named SR_1, the condenser is named SR_1_Cond, and the 
condenser duty stream is named SR_1_Energy.
 Figure 2.43-84
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ThPump Arounds Page
When you install the pump around, a Cooler is also installed. 
The default pump around specifications are the pump around 
rate and temperature drop. These are added on the Monitor 
page and Specs page of the Column property view. 
After you click the Install button, the Pump Around property 
view changes significantly, as shown in the figure below, 
allowing you to change pump around specifications, and view 
pump around calculated information. 
Vap Bypasses Page
As with the Pump Around, it is necessary to specify the draw 
and return stage, as well as the molar flow and duty for the 
vapour bypass. When you install the vapour bypass, the draw 
temperature and flowrate appear on the vapour bypass property 
view.
 Figure 2.44
When installing a Pump Around, it is necessary to specify the 
draw stage, return stage, molar flow, and duty.-85
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-86 Column Property View
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ThThe vapour bypass flowrate is automatically added as a 
specification. The figure below shows the vapour bypass 
property view once the side operation has been installed.
Side Draws Page
The Side Draws page allows you to view, and edit information 
regarding the side draw streams in the column. The following is 
the information included on this page:
• Draw Stream
• Draw Stage
• Type (Vapour, Liquid or Water)
• Mole Flow
• Mass Flow
• Volume Flow
Rating Tab
The Rating tab has several pages, which are described in the 
 Figure 2.45-86
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Column Operations -87
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Thtable below.
Page Description
Tray 
Sections
Provides information regarding tray sizing. On this page, 
you can specify the following:
• Tray Section (Name)
• Uniform Section. When this option is selected all tray 
stages have the same physical setup (diameter, tray 
type, and so forth).
• Internal Type (tray type)
• Tray Diameter
• Tray Space
• Tray Volume
• Disable Heat Loss Calcs
• Heat Model
• Rating Calculations
• Hold Up (ft3). If you delete the weir height, you can 
then enter the hold up value, and the weir height is 
back-calculated.
• Weeping Factor. The value is used to adjust the 
weeping in dynamic mode for low pressure drops.
Vessels Provides information regarding vessel sizing. On this page, 
you can specify the following:
• Vessel (Name)
• Diameter
• Length
• Volume
• Orientation
• Vessel has a Boot
• Boot Diameter
• Boot Length
• Hold Up (ft3)
Equipment Contains a list of Other Equipment in the Column flowsheet.
Pressure 
Drop
Contains information regarding pressure drop across the 
column. On this page you can specify the following 
information:
• Pressure Tolerance
• Pressure Drop Tolerance
• Damping Factor
• Maximum Pressure Iterations
• Top and Bottom column pressures-87
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-88 Column Property View
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ThTray Sections Page
The Tray Sections page contains all the required information for 
correctly sizing the column tray sections. 
The tray section diameter, weir length, weir height, and the tray 
spacing are required for an accurate and stable dynamic 
simulation. You must specify all the information on this page. 
With the exception of the tray volume, no other calculations are 
performed on this page. 
For multipass trays, simply enter the column diameter and the 
appropriate total weir length.
The required size information for the tray section can be 
calculated using the Tray Sizing utility.
 Figure 2.46-88
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ThVessels Page
The Vessels page contains the necessary sizing information for 
the different vessels in the column subflowsheet.
Equipment Page
The Equipment page contains a list of all the additional 
equipment, which is part of the column subflowsheet. The list 
does not contain equipment, which is part of the original 
template. Any extra equipment, which is added to the 
subflowsheet (pump arounds, side strippers, and so forth) is 
listed here. Double-clicking on the equipment name opens its 
property view on the Rating tab.
 Figure 2.47
This page is not available in the Liquid-Liquid Extractor.-89
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-90 Column Property View
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ThPressure Drop Page
The Pressure Drop page allows you to specify the pressure drop 
across individual trays in the tray section. The pressure at each 
individual stage can also be specified. The Pressure Solving 
Options group allows you to adjust the following parameters:
• Pressure Tolerance
• Pressure Drop Tolerance
• Damping Factor
• Maximum Pressure Iterations 
Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the unit operation. The PF Specs page contains a 
summary of the stream property view’s Dynamics tab.
 Figure 2.48
This page is not available in the Liquid-Liquid Extractor.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.-90
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Th 
Performance Tab
On the Performance tab, you can view the results of a converged 
column on the Summary page, Column Profiles page, and 
Feeds/Products page. You can also view the graphical and 
tabular presentation of the column profile on the Plots page.
Summary Page
The Summary page gives a tabular summary of the feed and 
product stream compositions, flows or the % recovery of the 
components in the product streams. When you select the 
Recovery radio button, the feed table displays the feed stream 
flowrate.
The Column Environment also has its own Workbook.
You can view the results in molar, mass or liquid volume, by 
selecting the appropriate basis radio button.
 Figure 2.49-91
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ThColumn Profiles Page
The Column Profiles page gives a tabular summary of Column 
stage temperatures, pressures, flows, and duties. 
You can change the basis for which the data appears by 
selecting the appropriate radio button from the Basis group. 
 Figure 2.50
The liquid and vapour flows are net flows for each stage.
The Heat Loss column is empty unless you select a heat flow 
model in the column subflowsheet of Main TS property view 
on the Rating tab.-92
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ThFeeds/Products Page
The Feeds/Products page gives a tabular summary of feed and 
product streams tray entry/exit, temperatures, pressures, flows, 
and duties.
You can change the basis of the data by selecting the 
appropriate radio button from the Basis group. For the feeds and 
draw Streams, the VF column to the right of each flow value 
indicates whether the flow is vapour (V) or liquid (L). If the feed 
has been split, a star (*) follows the phase designation. If there 
is a duty stream on a stage, “Energy” appears in the Type 
column. The direction of the energy stream is indicated by the 
sign of the duty. 
 Figure 2.51
You can split a feed stream into its phase components either 
on the Setup page of the Flowsheet tab in the column 
property view or on the Options page of the Simulation tab in 
the Session Preferences property view.-93
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-94 Column Property View
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ThPlots Page
On the Plots page, you can view various column profiles or assay 
curves in a graphical or tabular format.
Select the Live Updates checkbox to update the profiles with 
every pass of the solver (in other words, a dynamic update). 
This checkbox is cleared by default, because the performance of 
the column can be a bit slower if the checkbox is selected and a 
profile is open.
Tray by Tray Properties Group
To view a column profile, follow this generalized procedure:
1. Select a profile from the list in the Tray by Tray Properties 
group. 
The choices include: Temperature, Pressure, Flow, Transport 
Properties, Composition, K Value, Light/Heavy Key, and 
Electrolyte Properties.
 Figure 2.52
Electrolyte Properties are only available for cases with an 
electrolyte system.-94
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Column Operations -95
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Th2. In the Column Tray Ranges group, select the appropriate 
radio button:
3. After selecting a tray range, click either the View Graph 
button or the View Table button to display a plot or table 
respectively. 
To make changes to the plot, right-click in the plot area, and 
select Graph Control from the object inspect menu.
Radio Button Action
 All Displays the selected profile for all trays connected to the 
column (for example, main tray section, side strippers, 
condenser, reboiler, and so forth).
Single Tower From the drop-down list, select a tray section.
The main tray section along with the condenser and 
reboiler are considered one section, as is each side stripper.
From/To Use the drop-down lists to specify a specific range of the 
column. The first field contains the tray that is located at a 
higher spot in the tower (for example, for top to bottom 
tray numbering, the first field could be tray 3 and the 
second tray 6).
 Figure 2.53
Plots and tables are expandible property views that can 
remain open without the column property view.
Refer to Section 1.3.1 - 
Graph Control 
Property View for 
more information.-95
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-96 Column Property View
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ThDepending on the profile selected, you have to make further 
specifications. For certain profiles, there is a Properties button 
on both the profile plot and table. By clicking this button, the 
Properties property view appears, where you can customize the 
display of your profile. Changes made on the Properties property 
view affect both the table and plot.
A description of the specifications available for each profile type 
are outlined in the following table.
Profile Type Description
Temperature 
Profile
Displays the temperature for the tray range selected. 
No further specification is needed.
Pressure Profile Displays the pressure of each tray in the selected 
range. No further specification is needed.
Flow Profile Displays the flow rate of each tray in the selected 
range. You can customise the data displayed using the 
Properties property view.
In the Basis group, select molar, mass or liquid volume 
for your flow profile basis.
In the Phase group, select the checkbox for the flow of 
each phase that you want to display. Multiple flows can 
be shown. If three phases are not present in the 
column, the Heavy Liquid checkbox is not available, 
and thus, the Light Liquid checkbox represents the 
liquid phase.
In the Tray Flow Basis group, you can specify the stage 
tray flow basis by selecting the appropriate radio 
button: 
• Net. The net basis option only includes interstage 
flow.
• Total. The total basis option includes draw and 
pump around flow.-96
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Column Operations -97
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ThTransport 
Properties 
Profile 
Displays the selected properties from each tray in the 
selected range. You can customise the data displayed 
using the Properties property view:
In the Basis group, select molar or mass for the 
properties profile basis.
In the Phase group, select the checkbox for the flow of 
each phase that you want to display on the graph. 
Multiple flows can be shown. If three phases are not 
present in the column, the Heavy Liquid checkbox is 
not available. The Properties Profile table displays all 
of the properties for the phase(s) selected.
In the Axis Assignment group, by selecting a radio 
button under Left, you assign the values of the 
appropriate property to the left y-axis. To display a 
second property, choose the radio button under Right. 
The right y-axis then shows the range of the second 
property. If you want to display only one property on 
the plot, select the None radio button under Right.
Profile Type Description-97
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ThComposition Displays the selected component’s mole fraction of 
each tray in the selected range. You can customise the 
data displayed using the Properties property view.
In the Basis group, select molar, mass or liquid volume 
for the composition profile basis.
In the Phase group, select the checkbox for the flow of 
each phase that you want to display. Multiple flows can 
be shown. If the three phases are not present in the 
column, the Heavy Liquid checkbox is not available, 
and thus, the Light Liquid checkbox represents the 
liquid phase.
Choose either Fractions or Flows in the Comp Basis 
group by selecting the appropriate radio button.
The Components group displays a list of all the 
components that enter the tower. You can display the 
composition profile of any component by selecting the 
appropriate checkbox. The plot displays any 
combination of component profiles.
K Values Profile Displays the K Values of each tray in the selected 
range. You can select which components you want 
included in the profile using the Properties property 
view.
Profile Type Description-98
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ThLight/Heavy Key 
Profile
Displays the fraction ratio for each stage. You can 
customise the data displayed using the Properties 
property view.
In the Basis group, select molar, mass or liquid volume 
for the profile basis.
In the Phase group, select Vapour, Light Liquid or 
Heavy Liquid for the profile phase.
In the Light Key(s) and Heavy Key(s) groups, you can 
select the key component(s) to include in your profile.
Electrolyte 
Properties 
Profile
Displays the pH and ionic strength or the scale index 
depending on which radio button you select in the 
Graph Type group.
When you select the pH, Ionic Strength radio button, 
you can see how the pH value and ionic strength 
decrease or increase from tray to tray.
The Solid Components group displays a list of the 
solids that could form in the distillation column. You 
can select or clear the checkboxes to display or hide 
the scale tendency index value for the solid 
components in the table or graph. 
The scale tendency index value refers to its tendency 
to form at the given tray conditions. Solids with a scale 
tendency index greater than 1 form, if the solid 
formation is governed by equilibrium (as oppose to 
kinetics), and if there are no other solids with a 
common cation or anion portion which also has scale 
tendency greater than 1.
Profile Type Description-99
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ThAssay Curves Group
From the Assay Curves group, you can create plots and tables 
for the following properties:
• Boiling Point Assay
• Molecular Weight Assay
• Density Assay
• User Properties
For each of the options, you can display curves for a single tray 
or multiple trays. To display a plot or table, make a selection 
from the list, and click either the View Graph button or the 
View Table button. The figure below is an example of how a 
Boiling Point Properties plot appears.
 Figure 2.54
 Figure 2.55-100
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Column Operations -101
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ThData Control Property View
Click the Profile Data Control button, which is located on bottom 
left corner of every plot and table, to open the Data Control 
property view. This property view is common to all plots and 
tables on the Curves page. For a selected curve, all changes 
made on the Data Control property view affect the data of both 
the plot and table. 
The Data Control property view consists of five groups as shown 
in the figure below.
 Figure 2.56-101
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ThThe following table describes each data control option available 
according to group name.
Group Description
Style Select either the Multi Tray or Single Tray radio button. The 
layout of the Data Control property view differs slightly for 
each selection.
For the Single Tray selection, you must open the drop-
down list and select one tray.
If you select Multi Tray, the drop-down list is replaced by a 
list of all the trays in the column. Each tray has a 
corresponding checkbox, which you can select to display 
the tray property on the plot or table.
Properties Displays the properties available for the plot or table. Each 
Curve option has its own distinct Properties group. For a 
single tray selection, you can choose as many of the boiling 
point curves as required. Select the checkbox for any of the 
following options: TBP, ASTM D86, D86 Crack Reduced, 
D1160 Vac, D1160 ATM, and D2887. 
When multiple trays have been chosen in the Style group, 
the checkbox list is replaced by a drop-down list. You can 
only choose one boiling point curve when displaying 
multiple trays.
Basis Select molar, mass or liquid volume for the composition 
basis.
Phase Select the checkbox for the flow of each phase that you 
want displayed. Multiple flows can be shown. If there are 
not three phases present in the column, the Heavy Liquid 
checkbox is not available, and thus, the Light Liquid 
checkbox represents the liquid phase.
Visible 
Points
The radio buttons in the Visible Points group apply to the 
plots only. Select either the 15 Points or 31 Points option to 
represent the number of data points which appear for each 
curve.
Refer to Chapter 4 - 
Aspen HYSYS Oil 
Manager in the HYSYS 
Simulation Basis guide 
for details on boiling 
point curves.-102
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Column Operations -103
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ThTBP Envelope Group
The TBP Envelope group contains only the View Graph button. 
You can click the View Graph button to display a TBP Envelope 
curve as shown in the figure below.
Click the Profile Data Control button located on the property 
view above to open a property view for customizing your TBP 
Envelope curve.
 Figure 2.57
The curve allows you to view product stream distillation 
overlaid on the column feed distillation. This gives a visual 
representation of how sharp the separations are for each 
product. The sharpness of separation is adjusted using 
section and stripper efficiencies and front and back end 
shape factors. 
 Figure 2.58
Select a basis to define 
your TBP profile here.
Select from either 100 
or 200 data points for 
your TBP plot.
Select either a wet or 
dry basis. Dry basis is 
the default selection.-103
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-104 Column Property View
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ThFlowsheet Tab
The Flowsheet tab contains the following pages:
• Setup
• Variables
• Internal Streams
• Mapping
Setup Page
The Setup page defines the connections between the internal 
(subflowsheet) and external (Parent) flowsheets. 
To split all material inlet streams into their phase components 
before being fed to the column, select the Split All Inlets 
checkbox.
• If one of the material feed stream Split checkbox is 
clear, the Split All Inlets checkbox is cleared too.
• If you clear the Split All Inlets checkbox, none of the 
material inlet stream Split checkboxes are affected.
The Labels, as noted previously, attach the external flowsheet 
streams to the internal subflowsheet streams. They also 
perform the transfer (or translation) of stream information from 
the property package used in the parent flowsheet into the 
property package used in the Column subflowsheet (if the two 
 Figure 2.59-104
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Column Operations -105
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Thproperty packages are different). The default transfer basis used 
for material streams is a P-H Flash.
The Transfer Basis is significant only when the subflowsheet and 
parent flowsheet Property Packages are different.
When the Split checkbox for any of the inlet material streams is 
selected, the stream is split into its vapour and liquid phase 
components. The liquid stream is then fed to the specified tray, 
and the vapour phase to the tray immediately above the 
specified feed tray.
Energy streams and material streams connected to the top tray 
(condenser) cannot be split. The checkboxes for there variables 
appear greyed out.
The Flowsheet Topology group provides stage information for 
each element in the flow sheet.
Flash Type Action
T-P Flash The pressure and temperature of the material stream are 
passed between flowsheets. A new vapour fraction is 
calculated.
VF-T Flash The vapor fraction and temperature of the material stream 
are passed between flowsheets. A new Pressure is 
calculated.
VF-P Flash The vapor fraction and pressure of the material stream are 
passed between flowsheets. A new temperature is 
calculated.
P-H Flash The pressure and enthalpy of the material stream is passed 
between flowsheets. This is the default transfer basis.
User Specs You can specify the transfer basis for a material Stream.
None 
Required
No calculation is required for an energy stream. The heat 
flow is simply passed between flowsheets.
See the Summary page of the Performance tab to verify the 
split feed streams. An asterisk (*) following the phase 
indicator in the VF column indicates a split stream.
 Figure 2.60-105
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ThFlowsheet Variables Page (Main)
The Variables page allows you to select and monitor any 
flowsheet variables from one location. You can examine 
subflowsheet variables from the outside Column property view, 
without actually having to enter the Column subflowsheet 
environment.
You can add, edit or delete variables in the Selected Column 
flowsheet Variables group. 
Adding a Variable
To add a variable in the Selected Column Flowsheet Variables 
group:
1. Click the Add button.
2. From the Variable Navigator, select each of the parameters 
for the variable.
3. Click the OK button.
4. The variable is added to the Selected Column Flowsheet 
Variables group.
 Figure 2.61
You can also use the Specifications page to view certain 
variables. Select the variable by adding a specification, and 
ensure that the Active and Estimate checkboxes are clear. 
The value of this variable appears in the Current value 
column, and this “pseudo-specification” do not affect the 
solution.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information on the 
Variable Navigator.-106
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Column Operations -107
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ThEditing a Variable
You can edit a variable in the Selected Column Flowsheet 
Variables group as follows:
1. Highlight a variable.
2. Click the Edit button.
3. Make changes to the selections in the Variable Navigator.
4. Click the OK button.
If you decide that you do not want to keep the changes 
made in the variable navigator, click the Cancel button.
Deleting a Variable
You can remove a variable in any of the following ways:
• Select a variable, and click the Delete button.
OR
• Select a variable, click the Edit button, and then click the 
Disconnect button on the Variable Navigator.
Internal Streams Page
On the Internal Streams page, you can create a flowsheet 
stream that represents any phase leaving any tray within the 
Column. Streams within operations attached to the main tray 
section (for example, side strippers, condenser, reboiler, and so 
forth) can also be targeted. Each time changes occur to the 
column, new information is automatically transferred to the 
stream which you have created.
 Figure 2.62-107
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ThTo demonstrate the addition of an internal stream, a stream 
representing the liquid phase flowing from tray 7 to tray 8 in the 
main tray section of a column is added:
1. Click the Add button.
2. In the Stream drop-down list, type the name of the stream 
named Liquid.
3. In the Stage drop-down list, select tray 6 or simply type 6, 
which locates the selection in the list.
4. In the Type drop-down list, select the phase that you want to 
represent. The options include Vapor, Liquid or Aqueous. 
Select Liquid in this case.
5. From the Net/Total drop-down list, select either Net or Total. 
For the stage 6 liquid, select Net. 
• Net represents the material flowing from the Stage you 
have selected to the next stage (above for vapour, below 
for liquid or aqueous) in the column. 
• Total represents all the material leaving the stage (for 
example, draws, pump around streams, and so forth). -108
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ThMapping Page
The Mapping page contains a table that displays the inlet and 
outlet streams from the column subflowsheet, and component 
maps for each boundary stream.
If the fluid package of the column is the same as the main 
flowsheet, component maps are not needed (because 
components are the same on each side of the column 
boundary). None Req'd is the only option in the drop-down list 
of the Into Sub-Flowsheet and Out of Sub-Flowsheet 
columns. If the fluid packages are different, you can choose a 
map for each boundary stream. HYSYS lists appropriate maps 
based on the fluid package of each stream across the boundary. 
Click the Overall Imbalance Into Sub-Flowsheet button or 
Overall Imbalance Out of Sub-Flowsheet button to view any 
mole, mass of liquid volume imbalance due to changes in fluid 
package. If there are no fluid package changes, then there are 
no imbalances.
 Figure 2.63
For more detail on the 
actual map collections 
and component maps 
themselves, refer to 
Chapter 6 - 
Component Maps in 
the HYSYS Simulation 
Basis guide.-109
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-110 Column Property View
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ThReactions Tab
Reactive distillation has been used for many years to carry out 
chemical reactions, in particular esterification reactions. The 
advantages of using distillation columns for carrying out 
chemical reactions include:
• the possibility of driving the reaction to completion 
(break down of thermodynamic limitations for a 
reversible reaction), and separating the products of 
reactions in only one unit, thus eliminating recycle and 
reactor costs.
• the elimination of possible side reactions by continuous 
withdrawal of one of the products from the liquid phase.
• the operation at higher temperatures (boiling liquid), 
thus increasing the rate of reaction of endothermic 
reactions.
• the internal recovery of the heat of reaction for 
exothermic reactions, thereby replacing an equivalent 
amount of external heat input required for boil-up. 
The Reactions tab allows you to attach multiple reactions to the 
column. The tab consists of two pages: 
• Stages. Allows you select the reaction set, and its scope 
across the column.
• Results. Displays the reaction results stage by stage.
This tab is not available for the Liquid-Liquid Extractor.
For any column in an electrolyte flowsheet, there is no 
option to add any reaction (reaction set) to the column. 
Conceptually, electrolyte thermo conducts a reactive and 
phase flash all together. HYSYS does not provide options to 
allow you to add external reactions to the unit operation.-110
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Column Operations -111
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ThBefore adding a reaction to a column, you must first ensure that 
you are using the correct column Solving Method. HYSYS 
provides three solving methods which allow for reactive 
distillation.     
Solving Method Reaction Type Reaction Phase
Sparse Continuation 
Solver
Kinetic Rate, Simple Rate, 
Equilibrium Reaction
Vapor, Liquid
Newton Raphson 
Inside-Out
Kinetic Rate, Simple Rate Liquid
Simultaneous 
Correction
Kinetic Rate, Simple Rate, 
Equilibrium Reaction
Vapor, Liquid, 
Combined Phase
The Sparse Continuation Solver method allows you to attach 
a reaction set to your column, which combines reaction 
types. Other solvers require that the attached reactions are 
of a single type.-111
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ThStages Page
The Stages page consists of the Column Reaction Stages group. 
The group contains the Column Reaction Stages table and three 
buttons.
Column Reaction Stages Table
The table consists of four columns, which are described in the 
table below.
 Figure 2.64
Column Description
Column 
Reaction Name
The name you have associated with the column reaction. 
This is not the name of the reaction set you set in the 
fluid package manager.
First Stage The highest stage of the stage range over which the 
reaction is occurring. 
Last Stage The lowest stage of the stage range over which the 
reaction is occurring. 
Active Activates the associated reaction thereby enabling it to 
occur inside the column.-112
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ThThe property view also contains three buttons that control the 
addition, manipulation, and deletion of column reactions. 
Column Reaction Property View
The Column Reaction property view allows you to add and revise 
column reactions.
The Column Reaction property view shown in the above figure 
consists of two groups:
• Reaction Set Information
The Reaction Set Information group allows you to select 
the reaction set, and the scope of its application.
• Reaction Information
The Reaction Information group contains thermodynamic 
and stoichiometric information about the reaction you 
are applying to the selected section of the column.
Button Description
New Allows you to add a new column reaction set via the 
Column Reaction property view. 
Edit Allows you to edit the column reaction set whose name is 
currently selected in Column Reaction Stages table. The 
selected reaction’s Column Reaction property view appears.
Delete Allows you to delete the column reaction set whose name is 
currently selected in the Column Reaction Stages table.
 Figure 2.65
For more information of 
the Column Reaction 
property view, refer to 
the section on the 
Column Reaction 
Property View.-113
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ThReaction Set Information Group
The Reaction Set Information group consists of six objects:
Reaction Information Group
The Reaction Information group contains the Reaction field, 
which allows you to select a reaction from the reaction set 
selected in the Reaction Set field. 
Click the View Reaction button to open the selected reaction’s 
Reaction property view. This group also contains three sub-
groups, which allow you to view or specify the selected reactions 
properties.
Objects Description
Name The name you would like to associate with the column 
reaction. This is the name that appears in the Column 
Reaction Name column of the Column Reaction Stages 
table.
Reaction Set Allows you to select a reaction set from a list of all the 
reaction sets attached to the fluid package.
First Stage The upper limit for the reaction that is to occur over a 
range of stages. 
Last Stage The lower limit for the reaction that is to occur over a range 
of stages.
Delete Deletes the Column Reaction from the column.
Active Allows you to enable and disable the associated column 
reaction.
Sub-group Description
Stoichiometry Allows you to view and make changes to the 
stoichiometric formula of the reaction currently 
selected in the Reaction drop-down list. The group 
contains three columns:
• Components. Displays the components involved 
in the reaction.
• Mole Wt. Displays the molar weight of each 
component involved in the reaction.
• Stoich Coeff. Stoichiometric coefficients 
associated with the reaction.-114
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ThResults Page
The Results page displays the results of a converged column. 
Basis Consists of two fields:
• Base Component. Displays the reactant to which 
the reaction extent is calculated. This is often the 
limiting reactant.
• Reaction Phase. Displays the phase for which 
the kinetic rate equations for different phases can 
be modeled in the same reactor. To see the 
possible reactions, click the Reaction Information 
button in the View Reaction group.
You can make changes to the fields in these groups. 
These changes affect all the unit operations associated 
with this reaction. Click the View Reactions button 
for more information about the attached reaction.
Heat and Balance 
Error
Consists of two fields:
• Reaction Heat. Displays the reaction heat.
• Balance Error. Displays any error in the mass 
balance around the reaction.
 Figure 2.66
Sub-group Description-115
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ThThe page consists of a table containing six columns. The 
columns are described in the following table:
If you have more than one reaction occurring at any particular 
stage, each reaction appears simultaneously.
Design Tips for Reactive Distillation
1Although the column unit operations allows for multiple column 
reactions and numerous column configurations, a general 
column topography can be subdivided into three sections: 
• Rectifying Section
• Reactive Section
• Stripping Section 
Column Description
1st column Displays the name/number of the column stage.
Rxn Name The name of the reaction occurring at this stage.
Base Comp The name of the reactant component to which the 
calculated reaction extent is applied.
Rxn Extent The consumption or production of the base component in 
the reaction.
Spec % Conv Displays the percentage of conversion specified by you.
Act % Conv Displays the percentage of conversion calculated by HYSYS.
The Rxn Extent results appear only if the Sparse 
Continuation Solver is chosen as the Solving Method.-116
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ThWhile the Rectifying and Stripping Sections are similar to 
ordinary distillation, a reactive distillation column also has a 
Reactive Section. The Reactive Section of the column is where 
the main reactions occur. There is no particular requirement for 
separation in this section.
There are several unique operational considerations when 
designing a reactive distillation column: 
• The operating pressure should be predicated on the 
indirect effects of pressure on reaction equilibrium. 
• The optimum feed point to a reactive distillation column 
is just below the reactive section. Introducing a feed too 
far below the reactive section reduces the stripping 
potential of the column and results in increased energy 
consumption.
• Reflux has a dual purpose in reactive distillation. 
Increasing the reflux rate enhances separation and 
recycles unreacted reactants to the reaction zone 
thereby increasing conversion.
• Reboiler Duty is integral to reactive distillation as it must 
be set to ensure sufficient recycle of unreacted, heavy 
reactant to the reaction zone without excluding the light 
reactant from the reaction zone, if the reboiler duty is too 
high or too low, conversion, and purity can be 
compromised.
 Figure 2.67
Strippin
g 
Reactive 
Section
Rectifyin
g Section-117
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-118 Column Property View
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ThDynamics Tab
The Dynamics tab contains the following pages:
• Vessels
• Equipment
• Holdup
If you are working exclusively in Steady State mode or your 
version of HYSYS does not support dynamics, you are not 
required to change any information on the pages accessible 
through this tab.
Vessels Page
The Vessels page contains a summary of the sizing information 
for the different vessels contained in the column subflowsheet. 
In addition, it contains the possible dynamic specifications for 
these vessels.
 Figure 2.68-118
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ThEquipment Page
The Equipment page displays the same information as the 
Equipment page on the Rating tab. The difference is that 
double-clicking on the equipment name opens its property view 
on the Dynamics tab.
Holdup Page
The Holdup page contains a summary of the dynamic 
information calculated by HYSYS.
Perturb Tab
The Perturb tab is only available in the Column Runner property 
view. The Perturb tab allows you to control the way column 
solver calculates the partial derivatives. There are two types of 
independent controls.
This page is not available for the Liquid-Liquid Extractor.
Column Description
Pressure Displays the calculated stage pressure.
Total Volume Displays the stage volume.
Bulk Liq Volume Displays the liquid volume occupying the stage.
Control Description
Low Level 
Analytic
The Analytic property derivatives checkbox allows you 
to turn On and Off low level analytic derivatives 
support (in other words, derivatives of thermodynamic 
properties like Fugacity, Enthalpy, and Entropy by 
Temperature, Pressure, and Composition). 
At present this facility is available for Peng Robinson or 
Soave-Redlich-Kwong property packages in Sparse 
Continuation Solver context.
Optimizer Level 
Analytic
HYSYS Optimizer (RTO+) allows calculation of column 
analytic derivatives by stream Temperature, Pressure, 
Component Flow, Column Spec specified value, and 
Tear Variables.-119
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ThThe Sparse analytic page allows you to select a particular 
method of column analytic derivatives calculation.
The Perturb method parameters group provides tuning 
parameters for analytic column derivatives calculator.
• Rigorous properties checkbox. If active, rigorous 
thermodynamic properties are applied in Jacobi matrix 
calculation. If inactive, simple models (controlled by 
Control panel of Sparse solver) are applied instead for 
Enthalpy and Fugacity of thermodynamic phases. The 
last option may expedite derivative calculations.
• Warm restart checkbox. If active, additional Sparse 
linear solver information is preserved between Analytic 
derivative calculator calls (faster solution of linear 
system). If inactive, no Sparse linear solver information 
is stored (memory economy).
• Skip Sparse Solve checkbox. If active, Column solution 
phase is skipped (may allow faster execution).
 Figure 2.69-120
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ThColumn Specification 
Types
This section outlines the various Column specification (spec) 
types available along with relevant details. Specs are added and 
modified on the Specs Page or the Monitor Page of the 
Design tab.
Adding and changing Column specifications is straightforward. If 
you have created a Column based on one of the templates, 
HYSYS already has default specifications in place. The type of 
default specification depends on which of the templates you 
have chosen.
Cold Property Specifications 
 Figure 2.70
Cold 
Property
Description
Flash Point Allows you to specify the Flash Point temperature (ASTM 
D93 flash point temperature closed cup) for the liquid or 
vapour flow on any stage in the column.
Pour Point Allows you to specify the ASTM Pour Point temperature for 
the liquid or vapour flow on any stage in the column.
RON Allows you to specify the Research Octane Number for the 
liquid or vapour flow on any stage.
Refer to the Default 
Replaceable 
Specifications in 
Section  - Templates for 
more information.-121
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ThComponent Flow Rate
The flow rate (molar, mass or volume) of any component, or the 
total flow rate for any set of components, can be specified for 
the flow leaving any stage. If a side liquid or vapour draw is 
present on the selected stage, these are included with the 
internal vapour and liquid flows.
Component Fractions
The mole, mass or volume fraction can be specified in the liquid 
or vapour phase for any stage. You can specify a value for any 
individual component, or specify a value for the sum of the mole 
fractions of multiple components.
Component Ratio
The ratio (molar, mass or volume fraction) of any set of 
components over any other set of components can be specified 
 Figure 2.71
 Figure 2.72-122
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Thfor the liquid or vapour phase on any stage.
Component Recovery
Component recovery is the molar, mass or volume flow of a 
component (or group of components) in any internal or product 
stream draw divided by the flow of that component (or group) in 
the combined tower feeds. As the recovery is a ratio between 
two flows, you specify a fractional value. Also, there is no need 
to specify a Flow Basis since this is a ratio of the same 
component between specified stream and the combined tower 
feeds.
Cut Point
This option allows a cut point temperature to be specified for the 
liquid or vapour leaving any stage. The types are TBP, ASTM 
D86, D1160 Vac, D1160 ATM, and ASTM D2887. For D86, you 
are given the option to use ASTM Cracking Factor. For D1160, 
you are given an Atmospheric Pressure option. The cut point can 
be on a mole, mass or volume fraction basis, and any value 
 Figure 2.73
 Figure 2.74-123
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Thfrom 0 to 100 percent is allowed. 
Draw Rate
The molar, mass or volume flowrate of any product stream draw 
can be specified.
Delta T (Heater/Cooler)
The temperature difference across a Heater or Cooler unit 
operation can be specified. The Heater/Cooler unit must be 
installed in the Column subflowsheet, and the HYSIM Inside-
Out, Modified HYSIM Inside-Out or Sparse Continuation solving 
methods must be selected on the Solver page of the Parameters 
tab.
 Figure 2.75
While initial and final cut points are permitted, it is often 
better to use 5 and 95 percent cut points to minimize the 
errors introduced at the extreme ends of boiling point 
curves.
 Figure 2.76-124
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ThDelta T (Streams)
The temperature difference between two Column subflowsheet 
streams can be specified.
Duty
You can specify the duty for an energy stream.
Duty Ratio
You can specify the duty ratio for any two energy streams. In 
addition to Column feed duties, the choice of energy streams 
also includes pump around duties (if available).
Feed Ratio
The Feed Ratio option allows you to establish a ratio between 
the flow rate on or from any stage in the column, and the 
external feed to a stage. You are prompted for the stage, flow 
 Figure 2.77
 Figure 2.78
 Figure 2.79-125
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Thtype (Vapor, Liquid, Draw), and the external feed stage. 
Gap Cut Point
The Gap Cut Point is defined as the temperature difference 
between a cut point (Cut Point A) for the liquid or vapour leaving 
one stage, and a cut point (Cut Point B) on a different stage. 
You have a choice of specifying the distillation curve to be used:
• TBP
• ASTM D86
• D1160 Vac
• D1160 ATM
 Figure 2.80
This type of specification is useful for turn down or overflash 
of a crude feed.
 Figure 2.81
This specification is best used in combination with at least 
one flow specification; using this specification with a 
Temperature specification can produce non-unique 
solutions.-126
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Th• ASTM D2887
You can define Cut Point A and Cut Point B, which together must 
total 100%. The cut points can be on a mole, mass or volume 
basis.
Liquid Flow
The net molar, mass or volume liquid (Light or Heavy) flow can 
be specified for any stage.
Physical Property 
Specifications
The mass density can be specified for the liquid or vapour on 
any stage.
 Figure 2.82
 Figure 2.83-127
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ThPump Around Specifications
Reboil Ratio
You can specify the molar, mass or volume ratio of the vapour 
 Figure 2.84
Specification Description
Flow Rate The flow rate of the Pump Around can be specified 
in molar, mass, or liquid volume units.
Temperature Drop Allows you to specify the temperature drop across a 
Pump Around exchanger. The conditions for using 
this specification are the same as that stated for the 
Pump Around return temperature.
Return 
Temperature
The return temperature of a Pump Around stream 
can be specified. Ensure that you have not also 
specified both the pump around rate and the duty. 
This would result in the three associated variables 
(flow rate, side exchanger duty, and temperature) 
all specified, leaving HYSYS with nothing to vary in 
search of a converged solution.
Duty You can specify the duty for any Pump Around.
Return Vapor 
Fraction
You can specify the return vapour fraction for any 
Pump Around.
Duty Ratio To specify a Pump Around duty ratio for a Column 
specification, add a Column Duty Ratio spec 
instead, and select the Pump Around energy 
streams to define the duty ratio. 
The Pump Around Rate, as well as the Pump Around 
Temperature Drop are the default specifications HYSYS 
requests when a pump around is added to the column.
Refer to Section  - Duty 
Ratio for more 
information.-128
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Thleaving a specific stage to the liquid leaving that stage.
Recovery
The Recovery spec is the recovery of the total feed flow in the 
defined outlet streams (value range between 0 and 1).
Reflux Feed Ratio
The Reflux Feed Ratio spec is the fraction of the reflux flow 
divided by the reference flow for the specified stage and phase.
 Figure 2.85
(2.7)
 Figure 2.86
(2.8)
 Figure 2.87
molar flow of draw stream
total molar feed flow
--------------------------------------------------------------- % recovery=
reflux flow
reference flow
---------------------------------- reflux feed ratio=-129
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ThReflux Fraction Ratio
The Reflux Fraction Ratio spec is the fraction or % of liquid that 
is being refluxed on the specified stage (value range between 0 
and 1).
Reflux Ratio
The Reflux Ratio is the molar, mass or volume flow of liquid 
(Light or Heavy) leaving a stage, divided by the sum of the 
vapour flow from the stage plus any side liquid flow.
The Reflux Ratio specification is normally used only for top stage 
condensers, but it can be specified for any stage. For a Partial 
Condenser:
• Selecting the Include Vapour checkbox, gives the 
following equation for the reflux ratio:
• Clearing the Include Vapour checkbox, gives the 
following equation for the reflux ratio:
 Figure 2.88
 Figure 2.89
Reflux Ratio property view for 
three phase distillation column
Reflux Ratio property view 
for general column
Reflux Ratio R
V D+
-------------=
Reflux Ratio R
D
---=-130
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Thwhere:
R = liquid reflux to column
V = vapor product
D = distillate product
Tee Split Fraction
The split fraction for a Tee operation product stream can be 
specified. The Tee must be installed within the Column 
subflowsheet and directly attached to the column, for example, 
to a draw stream, in a pump around circuit, and so forth. Also, 
the Modified HYSIM Inside-Out solving method must be 
selected.
Tee split fraction specifications are automatically installed as 
you install the tee operation in the Column subflowsheet; 
however, you can select which specifications become active on 
the Monitor page or Specs page. Changes made to the split 
fraction specification value are updated on the Splits page of the 
tee operation.
Tray Temperature
 The temperature of any stage can be specified.
Transport Property 
Specifications
The viscosity, surface tension or thermal conductivity can be 
specified for the liquid leaving any stage. The viscosity or 
thermal conductivity can be specified for the vapour leaving any 
 Figure 2.90
Refer to Section 6.6 - 
Tee for details on the 
Tee operation.-131
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Thstage. A reference temperature must also be given.  
User Property 
A User Property value can be specified for the flow leaving any 
stage. You can choose any installed user property in the 
flowsheet, and specify its value. The basis used in the 
installation of the user property is used in the spec calculations.
Vapor Flow
The net molar, mass or volume vapor flow can be specified for 
any stage. Feeds and draws to that tray are taken into account.
The computing time required to satisfy a vapour viscosity 
specification can be considerably longer than that needed to 
meet a liquid viscosity specification.
 Figure 2.91
 Figure 2.92
 Figure 2.93-132
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ThVapor Fraction
The vapour fraction of a stream exiting a stage can be specified.
Vapor Pressure Specifications
Two types of vapour pressure specifications are available:
• true vapour pressure (@100°F)
• Reid vapour pressure.  
Column Stream 
Specifications
Column stream specifications must be created in the Column 
subflowsheet. Unlike other specifications, the stream 
specification is created through the stream’s property view, and 
not the Column Runner Specs page. To be able to add a 
specification to a stream:
 Figure 2.94
 Figure 2.95
Vapor Type Description
Vapor 
Pressure
The true vapour pressure at 100°F can be specified for the 
vapour or liquid leaving any stage.
Reid Vapor 
Pressure
Reid vapour pressure can be specified for the vapour or 
liquid leaving any stage. The specification must always be 
given in absolute pressure units.-133
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Th• The Modified HYSIM Inside-out solving method must be 
chosen for the solver.
• The stream must be a draw stream.
The Create Column Stream Spec button on the Conditions page 
of the Worksheet tab is available only on Stream property views 
within the Column subflowsheet. When you click on the Create 
Column Stream Spec button, the Stream Spec property view 
appears.
• For draw streams from a separation stage (tray section 
stage, condenser or reboiler) only a stream temperature 
specification can be set.
• For a non-separation stage streams (from pumps, 
heaters, and so forth) either a temperature or a vapour 
fraction specification can be set. 
• For any given stage, only one draw stream specification 
can be active at any given time.
Once a specification is added for a stream, the button on the 
Conditions page of the Worksheet tab changes from Create 
Column Stream Spec to View Column Stream Spec, and can be 
clicked to view the Stream Specification property view. 
Only one stream specification can be created per draw 
stream.
 Figure 2.96
Creating a new stream specification for a stage, or activating 
a specification automatically deactivates all other existing 
draw stream specifications for that stage.
You can only add Column Stream Specifications via the 
Stream property view of a draw stream within the Column 
subflowsheet.-134
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ThColumn-Specific 
Operations
The procedure for installing unit operations in a Column 
subflowsheet is the same as in the main flowsheet.
The UnitOps property view for the Column appears by selecting 
the Flowsheet | Add Operation command from the menu bar, 
or by pressing F12.
The unit operations available within the Column subflowsheet 
are listed in the following table. 
Most operations shown here are identical to those available in 
the main flowsheet in terms of specified and calculated 
 Figure 2.97
Operation Category Types
Vessels 3-Phase Condenser, Partial Condenser, Reboiler, 
Separator, Total Condenser, Tray Section
Heat Transfer 
Equipment
Cooler, Heater, Heat Exchanger
Rotating Equipment Pump
Piping Equipment Valve
Logicals Balance, Digital Pt, PID Controller, Selector Block, 
Transfer Function Block
Refer to Section 1.2.1 - 
Installing Operations 
for more information.-135
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Thinformation, property view structure, and so forth.
There are also additional unit operations which are not available 
in the main flowsheet. They are: 
• Condenser (Partial, Total, 3-Phase)
• Reboiler
• Tray Section
The Bypasses and Side Operations (side strippers, pump 
arounds, and so forth) are available on the Side Ops page of the 
Column property view.
 
Condenser
The Condenser is used to condense vapour by removing its 
latent heat with a coolant. In HYSYS, the condenser is used only 
in the Column Environment, and is generally associated with a 
Column Tray Section.
There are four types of Condensers:
Only the operations which are applicable to a Column 
operations are available within the Column subflowsheet.
You can open a property view of the Column PFD from the 
main build environment. This PFD only provides you with the 
ability to modify stream and operation parameters. You 
cannot add and delete operations or break stream 
connections. These tasks can only be performed in the 
Column subflowsheet environment.
Condenser Type Description
Partial Feed is partially condensed; there are vapour and 
liquid product streams. The Partial Condenser can be 
operated as a total condenser by specifying the vapour 
stream to have zero flowrate.
The Partial Condenser can be used as a Total 
Condenser simply by specifying the vapour flowrate to 
be zero.
Total Feed is completely condensed; there is a liquid product 
only.
Refer to Section 7.24.4 
- Access Column or 
Subflowsheet PFDs in 
the HYSYS User Guide 
for more information-136
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ThWhen you add a Column to the simulation using a pre-defined 
template, there can be a condenser attached to the tower (for 
example, in the case of a Distillation Column). 
To manually add a Condenser do one of the following:
• In the Column environment, press F12 and make the 
appropriate selection from the UnitOps property view.
• In the Column environment, press F4 and click a 
Condenser icon from the Column Palette.
The Condenser property view uses a Type drop-down list, which 
allows you to switch between condenser types without having to 
delete and re-install a new piece of equipment.
When you switch between the condenser types, the pages 
change appropriately. For example, the Connections page for 
the Total Condenser does not show the vapor stream. If you 
Three-Phase - 
Chemical
There are two liquid product streams and one vapour 
product stream.
Three-Phase - 
Hydrocarbon
There is a liquid product streams and a water product 
stream and one vapour product stream.
 Figure 2.98
Condenser Type Description
Partial Condenser icon
Total Condenser icon
Three-Phase Condenser 
icon-137
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Thswitch from the Partial to Total Condenser, the vapor stream is 
disconnected. If you then switch back, you have to reconnect 
the stream.
The Condenser property view has the same basic five tabs that 
are available on any unit operation:
• Design
• Rating
• Worksheet
• Performance
• Dynamics
It is necessary to specify the connections and the parameters 
for the Condenser. The information on the Dynamics tab are not 
relevant in steady state.
Design Tab
The Design tab contains options to configure the Condenser.
Connections Page
On the Connections page, you can specify the operation name, 
as well as the feed(s), vapour, water, reflux, product, and 
energy streams. 
 Figure 2.99-138
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ThThe Connections page shows only the product streams, which 
are appropriate for the selected condenser. For example, the 
Total Condenser does not have a vapour stream, as the entire 
feed is liquefied. Neither the Partial nor the Total Condenser has 
a water stream. 
The Condenser is typically used with a tray section, where the 
vapour from the top tray of the column is the feed to the 
condenser, and the reflux from the condenser is returned to the 
top tray of the column.
Parameters Page
The condenser parameters that can be specified are:
• Pressure Drop
• Duty
• Subcooling Data
 Figure 2.100
It is better to use a duty spec than specifying the heat flow 
of the duty stream.-139
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ThPressure Drop
The Pressure Drop across the condenser (Delta P) is zero by 
default. It is defined in the following expression:
where:  
P = vessel pressure
Pv = pressure of vapour product stream
Pl = pressure of liquid product stream
Pfeed = pressure of feed stream to condenser
 = pressure drop in vessel (Delta P)
Duty
The Duty for the energy stream can be specified here, but this is 
better done as a column spec (defined on the Monitor page or 
Specs page of the Column property view). This allows for more 
flexibility when adjusting specifications, and also introduces a 
tolerance.
The Duty should be positive, indicating that energy is being 
removed from the Condenser feed. 
The steady state condenser energy balance is defined as:
 
(2.9)
You typically specify a pressure for the condenser during the 
column setup, in which case the pressure of the top stage is 
the calculated value.
If you specify the duty, it is equivalent to installing a duty 
spec, and a degree of freedom is used.
Hfeed - Duty = Hvapour + Hliquid (2.10)
P Pv Pl Pfeed ΔP–= = =
ΔP-140
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Thwhere:  
Hfeed = heat flow of the feed stream to the condenser
Hvapour = heat flow of the vapour product stream
Hliquid = heat flow of the liquid product stream(s)
SubCooling
In some instances, you want to specify Condenser SubCooling. 
In this situation, either the Degrees of SubCooling or the 
SubCooled Temperature can be specified. If one of these fields 
is set, the other is calculated automatically.
Estimate Page
On the Estimate page you can estimate the flows and phase 
compositions of the streams exiting the Condenser.
You can enter any value for fractional compositions, and click 
the Normalize Composition button to have HYSYS normalize the 
values such that the total equals 1. This button is useful when 
In steady state, SubCooling applies only to the Total 
Condenser. There is no SubCooling in dynamics. 
 Figure 2.101-141
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Thmany components are available, but you want to specify 
compositions for only a few. HYSYS also specifies any  
compositions as zero.
HYSYS re-calculates the phase composition estimates when you 
click the Update Comp. Est. button. Clicking this button also 
removes any of the estimated values you entered for the phase 
composition estimates.
Click the Clear Comp. Est. button to clear the phase 
compositions estimated by HYSYS. This button does not remove 
any estimate values you entered. You can clear the all estimate 
values by clicking the Clear All Comp. Est. button. -142
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general. 
Rating Tab
The Rating tab contains options that are applicable in both 
Steady State and Dynamics mode.
Sizing Page
The Sizing page contains all the required information for 
correctly sizing the condenser. 
You can select either vertical or horizontal orientation, and 
cylinder or sphere. You can either enter the volume or 
 Figure 2.102
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.-143
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Thdimensions for your condenser. You can also indicate whether or 
not the condenser has a boot associated with it. If it does, then 
you can specify the boot dimensions.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. The information provided in the 
Nozzles page is applicable only in Dynamic mode.
 Figure 2.103
Refer to Section 1.3.6 
- Nozzles Page for 
more information.-144
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ThHeat Loss Page
The Heat Loss page allows you to specify the heat loss from 
individual trays in the tray section. You can choose either a 
Direct Q, Simple, or Detailed heat loss model or no heat loss 
from the Heat Loss Mode group.
Direct Q Heat Loss Model
The Direct Q model allows you to either specify the heat loss 
directly, or have the heat loss calculated from the Heat Flow for 
the condenser.
 Figure 2.104
 Figure 2.105-145
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ThSimple Heat Loss Model
The Simple model allows you to calculate the heat loss from 
these specified values: 
• Overall U value
• Ambient Temperature
Detailed Heat Loss Model
The Detailed model allows you to specify more detailed heat 
transfer parameters.
Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Condenser. 
 Figure 2.106
 Figure 2.107
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.6.1 
- Detailed Heat Model 
in the HYSYS Dynamic 
Modeling guide for 
more information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.-146
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ThPerformance Tab
The Performance tab has the following pages:
• Plots 
• Tables
• SetUp
From these pages you can select the type of variables you want 
to calculate and plot, view the calculated values, and plot any 
combination of the selected variables. The default selected 
variables are temperature, pressure, heat flow, enthalpy, and 
vapor fraction. At the bottom of the Plots or Tables page, you 
can specify the interval size over which the values should be 
calculated and plotted.
 Figure 2.108
In steady state, the displayed plots are all straight lines. 
Only in Dynamic mode, when the concept of zones is 
applicable, do the plots show variance across the vessels.-147
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ThDynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• StripChart
• Heat Exchanger
You are not required to modify information on the Dynamics tab 
when working in Steady State mode.
Specs Page
The Specs page contains information regarding initialization 
modes, condenser geometry, and condenser dynamic 
specifications.
 Figure 2.109-148
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ThModel Details
In the Model Details group, you can specify the initial 
composition and amount of liquid that the separator should start 
with when you start dynamics. This is done via the initialization 
mode which is discussed in the table below. 
The condenser geometry can be specified in the Model Details 
group. The following condenser geometry parameters can be 
specified in the same manner as the Geometry group on Sizing 
page of the Rating tab:
• Volume
• Diameter
• Height (Length)
• Geometry (Level Calculator)
The Liquid Volume Percent value is also displayed in this group. 
You can modify the level in the condenser at any time. HYSYS 
then uses that level as an initial value when the integrator is 
run. 
The Fraction Calculator determines how the level in the 
condenser and the elevation and diameter of the nozzle affects 
the product composition. There is only one Fraction Calculation 
Initialization Mode Description
Initialize from 
Products
The composition of the holdup is calculated from a 
weighted average of all products exiting the 
holdup. A PT flash is performed to determine other 
holdup conditions. The liquid level is set to the 
value indicated in the Liq Volume Percent field.
Dry Startup The composition of the holdup is calculated from a 
weighted average of all feeds entering the holdup. 
A PT flash is performed to determine other holdup 
conditions. The liquid level in the Liq Volume 
Percent field is set to zero.
Initialize from User The composition of the liquid holdup in the 
condenser is user specified. The molar composition 
of the liquid holdup can be specified by clicking the 
Init Holdup button. The liquid level is set to the 
value indicated in the Liq Volume Percent field.
The Initialization Mode can be changed any time when the 
integrator is not running. The changes cause the vessel to 
re-initialize when the integrator is started again.
Refer to the section on 
the Nozzles Page for 
more details.-149
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Thmode available, it is called Use Levels and Nozzles. The 
calculations are based on how the nozzle location and vessel 
liquid level affect the product composition. 
Dynamic Specifications
The Dynamic Specifications group contains fields, where you can 
specify what happens to the pressure and reflux ratio of the 
condenser when you enter dynamic mode.
The Fixed Pressure Delta P field allows you to impose a fixed 
pressure drop between the vessel and all of the feed streams. 
This is mostly supported for compatibility with Steady State 
mode. In Dynamic mode, you are advised to properly account 
for all pressure losses by using the appropriate equipment such 
as valves or pumps or static head contributions. A zero pressure 
drop should preferably be used here otherwise you may get 
unrealistic results such as material flowing from a low to a high 
pressure area.
The Fixed Vessel Pressure field allows you to fix the vessel 
pressure in Dynamic mode. This option can be used in simpler 
models where you do not want to configure pressure controllers 
and others, or if the vessel is open to the atmosphere. In 
general the specification should not be used, because the 
pressure should be determined by the surrounding equipment.
The Reflux Flow/Total Liquid Flow field provides you with a 
simple reflux ratio control option, and the ratio determines the 
reflux flow rate divided by the sum of the reflux and distillate 
flow rates.    
The Add/Configure Level Controller button installs a level 
controller on the distillate (liquid) outlet stream if one is not 
already present. If this stream has a valve immediately 
This option allows you to set up simple models without 
having to add the valves, pumps, and controller that would 
normally be present. This option does not always give 
desirable results under all conditions such as very low levels 
or reversal of some of the streams.-150
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Thdownstream of the vessel, the controller is configured to control 
the valve rather than the stream directly. In any case, the 
controller is configured with some basic tuning parameters, but 
you can adjust those. 
The default tuning values are as follows: 
• Kp = 1.8
• Ti = 4 * Residence time / Kp
Holdup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
The Levels group displays the following variables for each of the 
phases available in the vessel:
• Level. Height location of the phase in the vessel.
• Percent Level. Percentage value location of the phase in 
the vessel.
• Volume. Amount of space occupied by the phase in the 
vessel.
 Figure 2.110
Refer to Section 1.3.3 
- Holdup Page for 
more information.-151
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ThStripChart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
Heat Exchanger Page
The Heat Exchanger page opens a list of available heating 
methods for the unit operation. This page contains different 
objects depending on which configuration you select.
• If you select the None radio button, this page is blank 
and the Condenser has no cooling source.
• If you select the Duty radio button, this page contains 
the standard cooling parameters and you have to specify 
an energy stream for the Condenser.
• If you select the Tube Bundle radio button, this page 
contains the parameters used to configure a kettle chiller 
and you have to specify the required material streams 
for the kettle chiller.
 Figure 2.111
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
Refer to Duty Radio 
Button for more 
information.
Refer to Tube Bundle 
Radio Button for more 
information.-152
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ThDuty Radio Button
When the Duty radio button is selected the following heat 
transfer options are available.
The Heater Type group has two radio buttons: 
• Gas Heater. When you select this radio button, the duty 
is linearly reduced so that it is zero at liquid percent level 
of 100%, unchanged at liquid percent level of 50%, and 
doubled at liquid percent level of 0%. 
The following equation is used:
where:
Q = total heat applied to the holdup
L= liquid percent level 
QTotal = duty calculated from the duty source
The heat applied to the Condenser operation directly 
varies with the surface area of vapour contacting the 
vessel wall.
The Tube Bundle options are only available in Dynamics 
mode.
If you switch from Duty option or Tube Bundle option to 
None option, HYSYS automatically disconnects the energy or 
material streams associated to the Duty or Tube Bundle 
options.
 Figure 2.112
(2.11)Q 2 0.02L–( )QTotal=-153
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Th  
• Vessel Heater. When you select this radio button, 
100% of the duty specified or calculated in the SP cell is 
applied to the vessel’s holdup. That is:
where:  
Q = total heat applied to the holdup
QTotal = duty calculated from the duty source
The Duty Source group has two radio buttons:
• Direct Q
• From Utility
 Figure 2.113
The Gas Heater method is available only for condensers, 
because the heat transfer in the Condenser depends more on 
the surface area of the vapour contacting the cooling coils 
than the liquid.
Q = QTotal (2.12)
The Vessel Heater method is a non-scaling method.
0 20 40 60 80 100
0
40
80
120
160
200
Liquid Percent Level, L
Pe
rc
en
t 
o
f 
H
ea
t 
A
p
p
lie
d
Percent Heat Applied to Condenser-154
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ThWhen you select the Direct Q radio button, the Direct Q Data 
group appears. The following table describes the purpose of 
each object in the group.
When you select the From Utility radio button, the Utility Flow 
Properties group appears. 
The following table describes the purpose of each object that 
appears when the From Utility radio button is selected.
Object Description
SP The heat flow value in this cell is the same value specified 
in the Duty field on the Parameters page of the Design tab. 
Any changes made in this cell are reflected on the Duty 
field on the Parameters page of the Design tab.
Min. 
Available
Allows you to specify the minimum amount of heat flow.
Max. 
Available
Allows you to specify the maximum amount of heat flow.
 Figure 2.114
Object Description
Heat Flow Displays the heat flow value.
UA Displays the overall heat transfer coefficient.
Holdup Displays the amount of holdup fluid in the condenser.
Flow Displays the amount of fluid flowing out of the 
condenser.
Min. Flow Displays the minimum amount of fluid flowing out of 
the condenser.
Max. Flow Displays the maximum amount of fluid flowing out of 
the condenser.
Heat Capacity Displays the heat capacity of the fluid.
The cells containing:
• black text indicates 
the value is 
calculated by HYSYS 
and cannot be 
changed.
• blue text indicates 
the value is entered 
by you, and you can 
change the value.
• red text indicates the 
value is calculated by 
HYSYS, and you can 
change the value.-155
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ThReboiler
If you choose a Reboiled Absorber or Distillation template, it 
includes a Reboiler which is connected to the bottom tray in the 
tray section with the streams to reboiler and boilup.
The Reboiler is a column operation, where the liquid from the 
bottom tray of the column is the feed to the reboiler, and the 
boilup from the reboiler is returned to the bottom tray of the 
column.
The Reboiler is used to partially or completely vapourize liquid 
feed streams. You must be in a Column subflowsheet to install 
the Reboiler.
Inlet Temp. Displays the temperature of the stream flowing into 
the condenser.
Outlet Temp. Displays the temperature of the stream flowing out of 
the condenser.
Temp Approach Displays the value of the operation outlet temperature 
minus the outlet temperature of the Utility Fluid. It is 
only used when one initializes the duty valve via the 
Initialize Duty Valve button. 
Initialize Duty 
Valve
Allows you to initialize the UA, flow, and outlet 
temperature to be consistent with the duty for 
purposes of control.
 Figure 2.115
Object Description-156
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ThTo install the Reboiler operation do one of the following:
• In the Column environment, press F12 and select 
Reboiler from the UnitOps property view.
• In the Column environment, press F4 and click the 
Reboiler icon in the Column Palette.
The Reboiler property view has the same basic tabs that are 
available on any unit operation:
• Design
• Rating
• Worksheet
• Performance
• Dynamics
It is necessary to specify the connections, and the parameters 
for the Reboiler. The information on the Dynamics tab are not 
relevant in steady state.
Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
Reboiler icon-157
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ThConnections Page
On the Connections page, you must specify the Reboiler name, 
as well as the feed(s), boilup, vapor draw, energy, and bottoms 
product streams. The vapor draw stream is optional.
Parameters Page
On the Parameter page, you can specify the pressure drop and 
energy used by the Reboiler. The pressure drop across the 
Reboiler is zero by default.
The Duty for the energy Stream should be positive, indicating 
that energy is being added to the Reboiler feed(s). If you specify 
the duty, a degree of freedom is used.
 Figure 2.116
 Figure 2.117-158
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ThThe steady state reboiler energy balance is defined as:
where:  
Hfeed = heat flow of the feed stream to the reboiler
Hvapour = heat flow of the vapour draw stream
Hbottoms = heat flow of the bottoms product stream
Hboilup = heat flow of the boilup stream
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Rating Tab
The Rating tab contains the following pages:
• Sizing
• Nozzles
• Heat Loss
It is recommended to define a duty specification on the 
Monitor page or Specs page of the Column property view, 
instead of specifying a value for the duty stream.
Hfeed + Duty = Hvapour + Hbottom + Hboilup (2.13)
Rating tab for a Reboiler is the same as the Rating tab for the 
Condenser.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.-159
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ThSizing Page
The Sizing page contains all the required information for 
correctly sizing the reboiler. You can select either vertical or 
horizontal orientation, and cylinder or sphere. You can either 
enter the volume or dimensions for your reboiler. You can also 
indicate whether or not the reboiler has a boot associated with 
it. If it does, you can specify the boot dimensions.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. The information provided in the 
Nozzles page is applicable only in Dynamic mode.
Heat Loss Page
The Heat Loss page allows you to specify the heat loss from 
 Figure 2.118
 Figure 2.119
Refer to Section 1.3.6 
- Nozzles Page for 
more information.-160
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Thindividual trays in the tray section. You can choose either a 
Direct Q, Simple or Detailed heat loss model or no heat loss 
from the Heat Loss Mode group.
Direct Q Heat Loss Model
The Direct Q model allows you to either specify the heat loss 
directly, or have the heat loss calculated from the Heat Flow for 
the reboiler.
Simple Heat Loss Model
The Simple model allows you to calculate the heat loss from 
these specified values: 
• Overall U value
• Ambient Temperature
Detailed Heat Loss Model
The Detailed model allows you to specify more detailed heat 
 Figure 2.120
 Figure 2.121
Refer to Section 1.6.1 - 
Detailed Heat Model in 
the HYSYS Dynamic 
Modeling guide for more 
information.-161
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Thtransfer parameters. 
Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Reboiler. 
Performance Tab
The Performance tab of the Reboiler has the same pages as the 
Performance tab of the Condenser:
• Plots
• Tables
 Figure 2.122
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.-162
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Th• SetUp
From these pages you can select the type of variables you want 
to calculate and plot, view the calculated values, and plot any 
combination of the selected variables. The default selected 
variables are temperature, pressure, heat flow, enthalpy, and 
vapor fraction. At the bottom of the Plots or Tables page, you 
can specify the interval size over which the values should be 
calculated and plotted.
Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• StripChart
• Heat Exchanger
 Figure 2.123
The Dynamics tab for a Reboiler is the same as the Dynamics 
tab for the Condenser.
You are not required to modify information on the Reboiler’s 
Dynamics tab when working in Steady State mode.-163
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ThSpecs Page
The Specs page contains information regarding initialization 
modes, reboiler geometry, and reboiler dynamic specifications.
Model Details
In the Model Details group, you can specify the initial 
composition and amount of liquid that the separator should start 
with when you start dynamics. This done via the initialization 
mode which is discussed in the table below. 
 Figure 2.124
Initialization 
Mode
Description
Initialize from 
Products
The composition of the holdup is calculated from a 
weighted average of all products exiting the holdup. A 
PT flash is performed to determine other holdup 
conditions. The liquid level is set to the value indicated 
in the Liq Volume Percent field.
Dry Startup The composition of the holdup is calculated from a 
weighted average of all feeds entering the holdup. A PT 
flash is performed to determine other holdup 
conditions. The liquid level in the Liq Volume Percent 
field is set to zero.
Initialize from 
User
The composition of the liquid holdup in the reboiler is 
user specified. The molar composition of the liquid 
holdup can be specified by clicking the Init Holdup 
button. The liquid level is set to the value indicated in 
the Liq Volume Percent field.-164
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Column Operations -165
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ThThe reboiler geometry can be specified in the Model Details 
group. The following reboiler geometry parameters can be 
specified in the same manner as the Geometry group on the 
Sizing page of the Rating tab:
• Volume
• Diameter
• Height (Length)
• Geometry (Level Calculator)
The Liquid Volume Percent value is also displayed in this group. 
You can modify the level in the condenser at any time. HYSYS 
then uses that level as an initial value when the integrator is 
run.
The Fraction Calculator determines how the level in the 
condenser, and the elevation and diameter of the nozzle affects 
the product composition. There is only one Fraction Calculation 
mode available, it is called Use Levels and Nozzles. The 
calculations are based on how the nozzle location and vessel 
liquid level affect the product composition.
Dynamic Specifications
The Dynamic Specifications group contains fields where you can 
specify what happens to the pressure of the reboiler when you 
enter dynamic mode.
The Feed Delta P field allows you to impose a fixed pressure 
drop between the vessel and all of the feed streams. This is 
mostly supported for compatibility with Steady State mode. In 
Dynamic mode, you are advised to properly account for all 
pressure losses by using the appropriate equipment such as 
valves or pumps or static head contributions. A zero pressure 
drop should preferably be used here otherwise you may get 
unrealistic results such as material flowing from a low to a high 
pressure area.
The Initialization Mode can be changed any time when the 
integrator is not running. The changes cause the vessel to 
re-initialize when the integrator is started again.
Refer to the section on 
the Nozzles Page for 
more information.-165
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ThThe Fixed Vessel Pressure field allows you to fix the vessel 
pressure in Dynamic mode. This option can be used in simpler 
models where you do not want to configure pressure controllers 
and others, or if the vessel is open to the atmosphere. In 
general the specification should not be used, because the 
pressure should be determined by the surrounding equipment.
Holdup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
The Levels group displays the following variables for each of the 
phases available in the vessel:
• Level. Height location of the phase in the vessel.
• Percent Level. Percentage value location of the phase in 
the vessel.
• Volume. Amount of space occupied by the phase in the 
vessel.
StripChart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation.
 Figure 2.125
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.-166
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ThHeat Exchanger Page
The Heat Exchanger page opens a list of available heating 
methods for the unit operation. This page contains different 
objects depending on which radio button you select.
• If you select the None radio button, this page is blank 
and the Condenser has no cooling source.
• If you select the Duty radio button, this page contains 
the standard heating parameters and you have to specify 
an energy stream for the Reboiler.
• If you select the Tube Bundle radio button, this page 
contains the parameters used to configure a kettle 
reboiler and you have to specify the required material 
streams for the kettle reboiler.
 Figure 2.126
The Tube Bundle options are only available in Dynamics 
mode.
If you switch from Duty option or Tube Bundle option to 
None option, HYSYS automatically disconnects the energy or 
material streams associated to the Duty or Tube Bundle 
options.
Refer to Duty Radio 
Button for more 
information.
Refer to Tube Bundle 
Radio Button for more 
information.-167
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ThDuty Radio Button
When the Duty radio button is selected the following heat 
transfer options are available.
The Heater Type group has two radio buttons:
• Liquid Heater
• Vessel Heater
For the Liquid Heater method, the duty applied to the vessel 
depends on the liquid level in the tank. The heater height value 
must be specified. The heater height is expressed as a 
percentage of the liquid level in the vessel operation. The 
default values are 5% for the top of the heater, and 0% for the 
bottom of the heater. These values are used to scale the 
amount of duty that is applied to the vessel contents.
 Figure 2.127
When you select the Liquid Heater radio button, the Heater 
Height as % Vessel Volume group appears. This group 
contains two cells: 
• Top of Heater
• Bottom of Heater
These cells are used to specify the heater height.
(2.14)
Q 0                      L B<( )
Q L B–
T B–
------------QTotal    B L T≤ ≤( )
Q QTotal             L T>( )
=
=
=
-168
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Thwhere:  
L = liquid percent level (%)
T = top of heater (%)
B = bottom of heater (%)
The Percent Heat Applied may be calculated as follows:
It is shown that the percent of heat applied to the vessel’s 
holdup directly varies with the surface area of liquid contacting 
the heater.
When you select the Vessel Heater radio button, 100% of the 
duty specified or calculated in the SP cell is applied to the 
vessel’s holdup:
where:  
Q = total heat applied to the holdup
(2.15)
 Figure 2.128
Q = QTotal (2.16)
Percent Heat Applied Q
QTotal
--------------- 100%×=
0 20 40 60 80 100
0
20
40
60
80
100
Liquid Percent Level, L
Pe
rc
en
t 
o
f 
H
ea
t 
A
p
p
lie
d
Percent Heat Applied for a Liquid Heater
B T-169
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ThQTotal = duty calculated from the duty source
The Duty Source group has two radio buttons:
• Direct Q
• From Utility
When you select the Direct Q radio button, the Direct Q Data 
group appears. The following table describes the purpose of 
each object in the group.
When you select the From Utility radio button, the Utility Flow 
Properties group appears.
Object Description
SP The heat flow value in this cell is the same value specified 
in the Duty field of the Parameters page on the Design tab. 
Any changes made in this cell is reflected on the Duty field 
of the Parameters page on the Design tab.
Min. 
Available
Allows you to specify the minimum amount of heat flow.
Max. 
Available
Allows you to specify the maximum amount of heat flow.
 Figure 2.129
The cells containing:
• black text indicates the 
value is calculated by 
HYSYS and cannot be 
changed.
• blue text indicates the 
value is entered by you, 
and you can change the 
value.
• red text indicates the 
value is calculated by 
HYSYS, and you can 
change the value.-170
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Column Operations -171
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ThThe following table describes the purpose of each object that 
appears when the From Utility radio button is selected.
Tray Section
At the very minimum, every Column Templates includes a tray 
section. An individual tray has a vapour feed from the tray 
below, a liquid feed from the tray above, and any additional 
feed, draw or duty streams to or from that particular tray. The 
property view for the tray section of a Distillation Column 
Object Description
Heat Flow Displays the heat flow value.
Available UA Displays the overall heat transfer coefficient.
Utility Holdup Displays the amount of holdup fluid in the reboiler.
Mole Flow Displays the amount of fluid flowing out of the reboiler.
Min Mole Flow Displays the minimum amount of fluid flowing out of 
the reboiler.
Max Mole Flow Displays the maximum amount of fluid flowing out of 
the reboiler.
Heat Capacity Displays the heat capacity of the fluid.
Inlet Temp. Displays the temperature of the stream flowing into 
the condenser.
Outlet Temp. Displays the temperature of the stream flowing out of 
the condenser.
Initialize Duty 
Valve
Allows you to initialize the UA, flow, and outlet 
temperature to be consistent with the duty for 
purposes of control.-171
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Thtemplate is shown in the figure below. 
The tray section property view contains the five tabs that are 
common to most unit operations:
• Design
• Rating
• Worksheet
• Performance
• Dynamics
You are not required to change anything on the Rating tab and 
Dynamics tab, if you are operating in Steady State mode.
 Figure 2.130-172
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ThDesign Tab
The Design tab contains the following pages:
• Connections
• Side Draws
• Parameters
• Pressures
• User Variables
• Notes
Connections Page
The Connections page of the Tray Section is used for specifying 
the names and locations of vapour and liquid inlet and outlet 
streams, feed streams, and the number of stages (see Figure 
2.130). When a Column template is selected, HYSYS inserts the 
default stream names associated with the template into the 
appropriate input cells. For example, in a Distillation Column, 
the Tray Section vapour outlet stream is To Condenser and the 
Liquid inlet stream is Reflux.
A number of conventions exist for the naming and locating of 
streams associated with a Column Tray Section:
• When you select a Tray Section feed stream, HYSYS by 
default feeds the stream to the middle tray of the column 
(for example, in a 20-tray column, the feed would enter 
on tray 10). The location can be changed by selecting the 
desired feed tray from the drop-down list, or by typing 
the tray number in the appropriate field.
• Streams entering and leaving the top and bottom trays 
are always placed in the Liquid or Vapor Inlet/Outlet 
fields.-173
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Th 
Side Draws Page
On the Side Draws page, you can specify the name and type of 
side draws taken from the tray section of your column. Use the 
radio buttons to select the type of side draw:
• Vapor
• Liquid
• Water 
Select the cells to name the side draw stream, and specify the 
tray from which it is taken.
Parameters Page
You can input the number of trays on the Parameters page. 
Specifying the location of a column feed stream to be either 
the top tray (tray 1 or tray N, depending on your selected 
numbering convention) or the bottom tray (N or 1) 
automatically results in the stream becoming the Liquid Inlet 
or the Vapour Inlet, respectively. If the Liquid Inlet or 
Vapour Inlet already exists, your specified feed stream is an 
additional stream entering on the top or bottom tray, 
displayed with the tray number (1 or N). A similar 
convention exists for the top and bottom tray outlet streams 
(Vapour Outlet and Liquid Outlet).
 Figure 2.131-174
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Column Operations -175
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ThThe trays are treated as ideal if the fractional efficiencies are set 
to 1. If the efficiency of a particular tray is less than 1, the tray 
is modeled using a modified Murphree Efficiency.
You can add or delete trays anywhere in the column by clicking 
the Customize button, and entering the appropriate information 
in the Custom Modify Number of Trays group. This feature 
makes adding and removing trays simple, especially if you have 
a complex column, and you do not want to lose any feed or 
product stream information. The figure below shows the 
property view that appears when the Customize button is 
clicked.
You can add and remove trays by:
• Specify a new number of trays in the Current Number 
of Trays field. 
This is the same as changing the number of theoretical 
trays on the Connections page. All inlet and outlet 
streams move appropriately; for example, if you are 
changing the number of trays from 10 to 20, a stream 
initially connected to tray 5 is now at tray 10, and a 
stream initially connected at stream 10 is now at tray 20.
• Add or remove trays into or from individual tray section.
By default, the Use Tray Section Name for Stage Name 
checkbox is selected.
 Figure 2.132
When you are adding or deleting trays, all Feeds remain 
connected to their current trays.-175
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ThAdding Trays
To add trays to the tray section:
1. Enter the number of trays you want to add in the Number of 
Trays to Add/Delete field.
2. Specify the tray number after, which you want to add the 
trays in the Tray to Add After or Delete First field.
3. Click the Add Trays button, and HYSYS inserts the trays in 
the appropriate place according to the tray numbering 
sequence you are using. All streams (except feeds) and 
auxiliary equipment below (or above, depending on the tray 
numbering scheme) the tray where you inserted is moved 
down (or up) by the number of trays that were inserted.
Removing Trays
To remove trays from the tray section:
1. Enter the number of trays you want to delete in the Number 
of Trays to Add/Delete field.
2. Enter the first tray in the section you want to delete in the 
Tray to Add After or Delete First field. 
3. Click the Remove Trays button. All trays in the selected 
section are deleted. If you are using the top-down 
numbering scheme, the appropriate number of trays below 
the first tray (and including the first tray) you specify are 
removed. If you are using the bottom-up scheme, the 
appropriate number of trays above the first tray (and 
including the first tray) you specify are removed.
4. Streams connected to a higher tray (numerically) are not 
affected; for example, if you are deleting 3 trays starting at 
tray number 6, a side draw initially at tray 5 remains there, 
but a side draw initially connected to tray 10 is now at tray 
7. Any draw streams connected to trays 6,7 or 8 are deleted 
with your confirmation to do so.
If you select the Side Stripper radio button or Side Rectifier 
radio button at the bottom of the property view, this affects the 
pressure profile. The pressure of the main tray section stage 
from which the liquid feed stream is drawn is used as the side 
stripper pressure, which is constant for all stages. The pressure 
of the main tray section stage from which the vapour feed -176
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Column Operations -177
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Thstream is drawn is used as the Side Rectifier pressure, which is 
constant for all stages.
Pressures Page
The Pressures page displays the pressure on each tray. 
Whenever two pressures are known for the tray section, HYSYS 
interpolates to find the intermediate pressures. For example, if 
you enter the Condenser and Reboiler Pressures through the 
Column Input Expert or Column property view, HYSYS calculates 
the top and bottom tray pressures based on the Condenser and 
Reboiler pressure drops. The intermediate tray pressures are 
then calculated by linear interpolation.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
 Figure 2.133
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.-177
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-178 Column-Specific Operations
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ThRating Tab
The Rating tab contains the following pages:
• Sizing
• Nozzles
• Heat Loss
• Efficiencies
• Pressure Drop
Sizing Page
The Sizing page contains the required information for correctly 
sizing column tray and packed sections. If the Sieve, Valve, 
Bubble Cap radio button with the Uniform Tray Data are 
selected, the following property view is shown. 
The tray section diameter, weir length, weir height, and the tray 
spacing are required for an accurate and stable dynamic 
simulation. You must specify all of the information on this page. 
The Quick Size button allows you to automatically and quickly 
size the tray parameters. The Quick Size calculations are based 
on the same calculations that are used in the Tray Sizing Utility.
 Figure 2.134
Each parameter is also 
discussed in Section 
14.18 - Tray Sizing.-178
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Column Operations -179
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ThHYSYS only calculates the tray volume, based on the weir 
length, tray spacing, and tray diameter. For multipass trays, 
simply enter the column diameter and the appropriate total weir 
length.
When you select the Packed radio button and the Uniform Tray 
Data section, the Sizing page changes to the property view 
shown below.
The stage packing height, stage diameter, packing type, void 
fraction, specified surface area, and Robbins factor are required 
for the simple dynamic model. HYSYS uses the stage packing 
dimensions and packing properties to calculate the pressure 
flow relationship across the packed section.
The required size information for the tray section can be 
calculated using the Tray Sizing utility.
 Figure 2.135
Packing Properties 
(Dynamics)
Description
Void Fraction Packing porosity, in other words, m3 void space/
m3 packed bed.
Specific Surface Area Packing surface area per unit volume of packing 
(m-1).-179
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-180 Column-Specific Operations
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ThTo specify Chimney and Sump tray types, the Non Uniform Tray 
Data Option must be selected from the Section Properties 
group. The Non Uniform Tray Data Option allows you to model a 
column with high fidelity by adjusting tray rating parameters on 
a tray by tray basis. 
For a Trayed section of a column, you can adjust the Internal 
Type of tray, Tray Spacing, Diameter, Weir Height, Weir Length, 
Robbins Factor A packing-specific quantity used in the Robbins 
correlation, which is also called the dry bed 
packing factor (m-1). The Robbins correlation is 
used to predict the column vapour pressure drop. 
For the dry packed bed at atmospheric pressure, 2 
the Robbins or packing factor is proportional to the 
vapour pressure drop. 
Static Holdup Static liquid, hst, is the m 3 liquid/ m 3 packed bed 
remaining on the packing after it has been fully 
wetted and left to drain. The static liquid holdup is 
a constant value.
Include Loading 
Regime Term
Loading regime term is the second term in the 
Robbins pressure drop equation, which is limited 
to atmospheric pressure and under vacuum but 
not at elevated pressures. When pressure is high, 
(in other words, above 1 atm), inclusion of the 
loading regime term may cause an unrealistically 
high pressure drop prediction. 
 Figure 2.136
Packing Properties 
(Dynamics)
Description-180
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Column Operations -181
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ThDC Volume, Flow Path and Weeping factor. For a Packed section 
of a column, you can adjust the Stage Packing Height, and 
Diameter.
From the Internal Type drop-down list in the Detailed Sizing 
Information group, you can select alternative internal tray types 
on a tray by tray basis.
The Chimney and Sump internals along with the weeping factor 
details are mentioned below.
Nozzles Page
The Nozzles page contains the elevations at which vapour and 
liquid enter or leave the tray section.
Heat Loss Page
The Heat Loss page allows you to specify the heat loss from 
individual trays in the tray section. You can select from either a 
Direct Q, Simple or Detailed heat loss model or have no heat 
loss from the tray sections.
Detailed Sizing 
Information
Description
Internal Type Chimney - This allows a higher liquid level and does 
not have any liquid going down to the tray below. 
Although vapor can go up through it but it does not 
contact the liquid. The Chimney tray type can be 
designated on any tray. By default, the weeping factor 
is set to 0 and the stage efficiency is set to 5% on the 
Efficiencies page. The weir height and tray spacing is 
increased for a tray section. For a packed section stage 
packing height is increased.
Sump - Only the bottom tray can be designated as a 
sump. By default, the efficiency is set to 5%. The tray 
spacing for a tray section and the stage packing height 
in a packed section are increased when using a Sump.
Weeping Factor The weeping factor can be adjusted on a tray by tray 
basis. It is used to scale back or turn off weeping. By 
default the weeping factor is set to 1 for all internal 
types except the sump.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.-181
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-182 Column-Specific Operations
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ThDirect Q Heat Flow Model
The Direct Q model allows you to input the heat loss directly 
where the heat flow is distributed evenly over each tray section. 
Otherwise you have the heat loss calculated from the Heat Flow 
for each specified tray section.
Using the checkbox, you can temporarily disable heat loss 
calculations without losing any Heat Loss data that is entered.
 Figure 2.137-182
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Column Operations -183
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ThSimple Heat Flow Model
The Simple model allows you to calculate the heat loss by 
specifying: 
• The Overall U value
• The Ambient Temperature°C
Detailed Heat Flow Model
The Detailed Heat Flow model allows you to specify more 
detailed heat transfer parameters. The detailed properties can 
be used on a tray to tray basis based on the temperature profile, 
conduction, and convection data specified.
 Figure 2.138
 Figure 2.139
Refer to Section 1.6.1 - 
Detailed Heat Model in 
the HYSYS Dynamic 
Modeling guide for more 
information.-183
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-184 Column-Specific Operations
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ThEfficiencies Page
As with steady state, you can specify tray efficiencies for 
columns in dynamics. However, you can only specify the overall 
tray efficiency; component tray efficiencies are only available in 
steady state.
Pressure Drop Page
The Pressure Drop page displays the information associated with 
the pressure drops (or pressures) across the tray section. 
Selecting the Rating Enabled checkbox turns on the pressure 
drop calculations as part of the column solution.
The tray sizing utility calculates a pressure drop across each 
tray, you need to fix one end of the column (top or bottom), 
allowing the other trays to float with the calculations. You can 
select which end of the column to be fixed by selecting the 
appropriate radio button in the Fix Tray group.
 Figure 2.140
The Pressure Drop page uses the same calculation in the 
Tray Sizing utility to calculate the pressure drop for the tray 
sections when the column is running. In other words, using 
the traffics and geometries to determine what the pressure 
drop is.-184
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Column Operations -185
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ThThe Tray Section Pressure Drop field displays the absolute 
overall pressure change between the fixed tray and the last tray 
at the other end.
Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Tray Section. 
Performance Tab
The Performance tab contains the following pages:
• Pressure
• Temperature
• Flow
• Summary
• Hydraulics
 Figure 2.141
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.-185
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-186 Column-Specific Operations
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ThPressure Page
The Pressure page contains a table that lists all the pressure for 
each tray. The table also includes the names of any inlet 
streams associated to a tray and the inlet streams’ pressure.
Temperature Page
The Temperature page contains a table that lists all the 
temperature for each tray. The table also includes the names of 
any inlet streams associated to a tray and the inlet streams’ 
temperature.
Flow Page
The Flow page contains a table that lists all the liquid and 
vapour flow rates for each tray. The table also includes the 
names of any inlet streams associated to a tray and the inlet 
streams’ flow rate. You can also change the unit of the flow 
rates displayed by selecting the unit from the Flow Basis drop-
down list. There are four possible units:
• Molar
• Mass
• Standard Liquid Volume
• Actual Volume
Summary Page
The Summary page contains a table that displays the flow rates, 
temperature, and pressure for each tray.
Hydraulics Page
The Hydraulics page contains a table that displays the height 
and pressure of Dry Hole DP, Static Head, and Height over Weir, 
and tray residence time.-186
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Column Operations -187
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ThThe tray residence time is computed as:
Where the Tray Liquid Molar Flow Rate is the maximum between 
the liquid molar flow rate from above the tray plus the liquid 
side feed molar flow rates and the liquid molar flow rate to 
below the tray plus the liquid side product molar flow rates.
The residence time of every tray is permanently compared 
against the column (composition) integrating step size to verify 
the accuracy of the dynamic simulation. The adopted criterion 
is:
Every tray residence time must be at least four times as long as 
the column integrating step.
Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• Static Head
• StripChart
Specs Page
The Specs page contains the Nozzle Pressure Flow k Factors for 
all the trays in the tray section. You can select to have HYSYS 
calculate the k value for all the trays by clicking the All Stages 
button. If you want HYSYS to calculate the k values for certain 
trays only, select the desired trays and click the Selected Stages 
button. HYSYS only calculates the k values for the selected 
Tray Residence Time Tray Liquid Holdup
Tray Liquid Molar Flow Rate
----------------------------------------------------------------------⎝ ⎠
⎛ ⎞=-187
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-188 Column-Specific Operations
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Thstages.
The Use tower diameter method checkbox, when selected, 
calculates the k values for the column based on the column 
diameter. When the checkbox is cleared the k values are 
calculated using the results obtained from the steady state 
model, providing a smoother transition between your steady 
state model and dynamic model.
The Model Weeping checkbox, when selected, takes into 
account any weeping that occurs on the tray sections and add 
the effects to your model.
The Perform dry start up checkbox allows you to simulate a 
dry start up. Selecting this checkbox removes all the liquid from 
all the trays when the integrator starts.
The Initialize From User checkbox allows you to start the 
simulation from conditions you specify. Selecting this checkbox, 
activates the Init HoldUp button. Click this button to enter the 
 Figure 2.142
Weeping can start to occur on a tray when the dry hole 
pressure loss drops below 0.015 kPa. It allows liquid to drain 
to the stage below even if the liquid height is below the weir 
height.-188
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Column Operations -189
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Thinitial liquid mole fractions of each component and the initial 
flash conditions.
The Fixed Pressure Profile checkbox allows you to simulate the 
column based on the fixed pressure profile.
Pressure Profile
The Fixed Pressure Profile checkbox allows you to run the 
column in Dynamic mode using the steady state pressure 
profile. This option simplifies the column solution for 
inexperienced users, and makes their transition from the steady 
state to dynamics simulation a bit easier.
The pressure profile of a tray section is determined by the static 
head, which is caused mostly by the liquid on the trays, and the 
frictional pressure losses, which are also known as dry hole 
pressure loses.
The frictional pressure losses are associated with vapour flowing 
through the tray section. The flowrate is determined by 
Equation (2.17). 
In HYSYS, the k-value is calculated by assuming:
However, if the Fixed Pressure Profile option is selected, then 
the static head contribution can be subtracted and hence the 
You do not have to configure pressure control systems with 
this option. This option is not recommended for rigorous 
modeling work where the pressure can typically change on 
response to other events.
(2.17)
(2.18)
flow k density friction pressure losses××=
kα Tray diameter( )2-189
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-190 Column-Specific Operations
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Thvapour flow and the frictional pressure loss is known. This allows 
the k-values to be directly calculated to match steady state 
results more closely.
Holdup Page
The Holdup page contains a summary of the dynamic simulation 
results for the column. The holdup pressure, total volume, and 
bulk liquid volume results on a tray basis are contained in this 
property view. Double-clicking on a stage name in the Holdup 
column opens the stage property view.
You can double-click on any cell within each row to view the 
advanced holdup properties for each specific tray section.-190
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Column Operations -191
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ThStatic Head Page
The Static Head page enables you to select how the static head 
contributes to the calculation.
Since static head contributions are often essential for proper 
column modeling, internal static head contributions are 
generally considered for the column model in any case, and 
should only be disabled under special circumstances.
StripChart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
Tee
The property view for the Tee operation in the Column 
subflowsheet has all of the pages and inherent functionality 
contained by the Tee in the Main Environment with one addition, 
the Estimates page.
 Figure 2.143
 Figure 2.144
Refer to Section 1.6.5 
- Static Head in the 
HYSYS Dynamic 
Modeling guide for 
more information.
Refer to Section 1.3.7 
- Stripchart Page/Tab 
for more information.
Refer to Chapter 6 - 
Piping Operations for 
more details on the 
property view of the TEE.
Refer to the section on 
the General Features of 
the Solving Methods for 
information on which 
method supports Tee 
operation.-191
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-192 Column-Specific Operations
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ThOn the Estimates page, you can help the convergence of the 
Column subflowsheet's simultaneous solution by specifying flow 
estimates for the tee product streams. To specify flow 
estimates:
1. Select one of the Flow Basis radio buttons: Molar, Mass or 
Volume.
2. Enter estimates for any of the product streams in the 
associated fields next to the stream name.
There are four buttons on the Estimates page, which are 
described in the table below.
If the Tee operation is attached to the column (for example, via 
a draw stream), one tee split fraction specification is added to 
the list of column specifications for each tee product stream that 
you specify. As you specify the split fractions for the product 
streams, these values are transferred to the individual column 
specifications on the Monitor page and Specs page of the 
column property view. 
Button Related Setting
Update Replaces all estimates except user specified estimates 
(in blue) with values obtained from the solution.
Clear Selected Deletes the highlighted estimate.
Clear Calculated Deletes all calculated estimates.
Clear All Deletes all estimates.
The additional pieces of equipment available in the Column 
subflowsheet are identical to those in the main flowsheet. 
For information on each piece of equipment, refer to its 
respective chapter. 
For example, for information on the Heat Exchanger, refer to 
Section 4.4 - Heat Exchanger in this manual. 
All operations within the Column subflowsheet environment 
are solved simultaneously.-192
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Column Operations -193
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ThRunning the Column
Once you are satisfied with the configuration of your Column 
subflowsheet and you have specified all the necessary input, the 
next step is to run the Column solution algorithm.
The iterative procedure begins when you click the Run button on 
the Column property view. The Run/Reset buttons can be 
accessed from any page of the Column property view.
When the Run button on the Column property view is clicked, 
the Run/Reset buttons are replaced by a Stop button which, 
when clicked, terminates the convergence procedure. The Run 
button can then be clicked again to continue from the same 
location. Similarly, the Stop icon switches to a grey shading 
with the Run icon on the toolbar after it is activated.
When you are working inside the Column build environment, the 
Column runs only when you click the Run button on the Column 
property view, or the Run icon on the toolbar. When you are 
working with the Column property view in the Main build 
environment, the Column automatically runs when you change:
• A specification value after a converged solution has been 
reached.
• The Active specifications, such that the Degrees of 
Freedom return to zero.
Run
The Run command begins the iterative calculations necessary to 
simulate the column described by the input. On the Monitor 
page of the Column property view, a summary showing the 
iteration number, equilibrium error, and the heat and 
specification errors appear. Detailed messages showing the 
When you are inside the Column build environment, a Run 
icon also appears on the toolbar, which has the same 
function as the Run button on the Column property view.
On the toolbar, the Run icon and Stop icon are two separate 
icons. Whichever icon is toggled on has light grey shading.
Run icon
Stop icon
Refer to Monitor Page 
from Section  - Design 
Tab for more 
information.-193
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-194 Running the Column
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Thconvergence status are shown in the Trace Window.
The default basis for the calculation is a modified “inside-out” 
algorithm. In this type of solution, simple equilibrium and 
enthalpy models are used in the inner loop, which solve the 
overall component and heat balances, vapour-liquid equilibrium, 
and any specifications. The outer loop updates the simple 
thermodynamic models with rigorous calculations.
When the simulation is running, the status line at the bottom of 
the screen first tracks the calculation of the initial properties 
used to generate the simple models. Then the determination of 
a Jacobian matrix appears, which is used in the solution of the 
inner loop. Next, the status line reports the inner loop errors 
and the relative size of the step taken on each of the inner loop 
iterations. Finally, the rigorous thermodynamics is again 
calculated and the resulting equilibrium, heat, and spec errors 
reported. The calculation of the inner loop and the outer loop 
properties continues until convergence is achieved, or you 
determine that the column cannot converge and click Stop to 
terminate the calculation.
If difficulty is encountered in converging the inner loop, the 
program occasionally recalculates the inner loop Jacobian. If no 
obvious improvement is being made with the printed equilibrium 
and heat and spec errors, click Stop to terminate the 
calculations and examine the available information for clues.
Refer to Section  - Column Troubleshooting for solutions to 
some common troubles encountered while trying to achieve the 
desired solution.
Any estimates which appear in the Column Profile page and 
Estimates page are used as initial guesses for the convergence 
algorithm. If no estimates are present, HYSYS begins the 
convergence procedure by generating initial estimates.
Refer to Estimates Page 
from Section  - 
Parameters Tab for 
more information.-194
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Column Operations -195
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ThReset
The Reset command clears the current Column solution, and 
any estimates appearing on the Estimates page of the Column 
property view. If you make major changes after getting a 
converged Column, it is a good idea to Reset to clear the 
previous solution. This allows the Column solver to start fresh 
and distance itself from the previous solution. If you make only 
minor changes to the Column, try clicking Run before Resetting.
Once the column calculation has started it continues until it has 
either converged, has been terminated due to a mathematically 
impossible condition, (for example being unable to invert the 
Jacobian matrix), or it has reached the maximum number of 
iterations. Other than these three situations, calculations 
continue indefinitely in an attempt to solve the column unless 
the Stop button is clicked. Unconverged results can be 
analysed, as discussed in Section  - Column 
Troubleshooting.
Column Troubleshooting
Although HYSYS does not require any initial estimates for 
convergence, good estimates of top and bottom temperatures 
and one product accelerate the convergence process. Detailed 
profiles of vapour and liquid flow rates are not required.
However, should the column have difficulty, the diagnostic 
output printed during the iterations provides helpful clues on 
how the tower is performing. If the equilibrium errors are 
approaching zero, but the heat and spec errors are staying 
relatively constant, the specifications are likely at fault. If both 
the equilibrium errors and the heat and spec errors do not 
appear to be getting anywhere, then examine all your input (for 
example the initial estimates, the specifications, and the tower 
configuration).
In running a column, keep in mind that the Basic Column 
Parameters cannot change. By this, it is meant that column 
pressure, number of trays, feed tray locations, and extra -195
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-196 Column Troubleshooting
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Thattachments such as side exchanger and pump around locations 
remain fixed. To achieve the desired specifications the Column 
only adjusts variables which have been specified as initial 
estimates, such as reflux, side exchanger duties, or product flow 
rates. This includes values that were originally specifications but 
were replaced, thereby becoming initial estimates. It is your 
responsibility to ensure that you have entered a reasonable set 
of operating conditions (initial estimates) and specifications 
(Basic Column Parameters) that permit solution of the column. 
There are obviously many combinations of column 
configurations and specifications that makes convergence 
difficult or impossible. Although all these different conditions 
could not possibly be covered here, some of the more frequent 
problems are discussed in the following sections.
Heat and Spec Errors Fail to 
Converge
This is by far the most frequent situation encountered when a 
column is unable to satisfy the allowable tolerance. The 
following section gives the most common ailments and 
remedies.
Poor Initial Estimates
Initial estimates are important only to the extent that they 
provide the initial starting point for the tower algorithm. 
Generally, poor guesses simply cause your tower to converge 
more slowly. However, occasionally the effect is more serious. 
Consider the following:
• Check product estimates using approximate splits. A 
good estimate for the tower overhead flow rate is to add 
up all the components in your feed which are expected in 
the overheads, plus a small amount of your heavy key 
component. If the tower starts with extremely high 
errors, check to see that the overhead estimate is 
smaller than the combined feed rates.-196
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Column Operations -197
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Th• Poor reflux estimates usually do not cause a problem 
except in very narrow boiling point separations. Better 
estimates are required if you have high column liquid 
rates relative to vapour rates, or vice versa.
• Towers containing significant amounts of inert gases (for 
example H2, N2, and so forth), require better estimates 
of overhead rates to avoid initial bubble point problems. 
A nitrogen rejection column is a good example.
Input Errors
It is good practice to check all of your input just before running 
your column to ensure that all your entries, such as the stage 
temperatures and product flow rates, appear reasonable:
• Check to ensure that your input contains the correct 
values and units. Typical mistakes are entering a product 
flow rate in moles/hr when you really meant to enter it in 
barrels/day, or a heat duty in BTU/hr instead of E+06 
BTU/hr.
• When specifying a distillate liquid rate, make sure you 
have specified the Distillate rate for the condenser, not 
the Reflux rate.
• If you change the number of trays in the column, make 
sure you have updated the feed tray locations, pressure 
specifications, and locations of other units such as side 
exchangers on the column.
• If the tower fails immediately, check to see if all of your 
feeds are known, if a feed was entered on a non-existent 
tray, or if a composition specification was mistakenly 
entered for a zero component.
To see the initial estimates, click the View Initial Estimates 
button on the Monitor page of the column property view.
Clicking the Input Summary button on the Monitor page of 
the column property view displays the column input in the 
Trace Window.-197
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-198 Column Troubleshooting
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ThIncorrect Configuration
For more complex tower configurations, such as crude columns, 
it is more important that you always review your input carefully 
before running the tower. It is easy to overlook a stripping feed 
stream, side water draw, pump around or side exchanger. Any 
one of these omissions can have a drastic effect on the column 
performance. As a result, the problem is not immediately 
obvious until you have reviewed your input carefully or tried to 
change some of the specifications.
• Check for trays which have no counter-current vapour-
liquid traffic. Examples of this are having a feed stream 
on a tray that is either below the top tray of an un-
refluxed tower or a tower without a top lean oil feed, or 
placing a feed stream above the bottom stage of a tower 
that does not have a bottom reboiler or a stripping feed 
stream below it. In both cases the trays above or below 
the feed tray become single phase. Since they do not 
represent any equilibrium mass transfer, they should be 
removed or the feed should be moved. The tower cannot 
converge with this configuration.
• The tower fails immediately if any of the sidestrippers do 
not have a stripping feed stream or a reboiler. If this 
should occur, a message is generated stating that a 
reboiler or feed stream is missing in one of the 
sidestrippers.
• Make sure you have installed a side water draw if you 
have a steam-stripped hydrocarbon column with free 
water expected on the top stage.
• Regardless of how you have approached solving crude 
columns in the past, try to set up the entire crude 
column with your first run, including all the side 
strippers, side exchangers, product side draws, and 
pump arounds attached. Difficulties arise when you try to 
set up a more simplified tower that does not have all the 
auxiliary units attached to the main column, then assign 
product specs expected from the final configuration.
Impossible Specifications
Impossible specifications are normally indicated by an 
unchanging heat and spec error during the column iterations 
even though the equilibrium error is approaching zero. To get 
around this problem you have to either alter the column 
configuration or operating pressure or relax/change one of the -198
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Column Operations -199
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Thproduct specifications.
• You cannot specify a temperature for the condenser if 
you are also using subcooling.
• If you have zero liquid flows in the top of the tower, 
either your top stage temperature spec is too high, your 
condenser duty is too low, or your reflux estimate is too 
low.
• If your tower shows excessively large liquid flows, either 
your purity specs are too tight for the given number of 
trays or your Cooler duties are too high.
• Dry trays almost always indicate a heat balance problem. 
Check your temperature and duty specifications. There 
are a number of possible solutions: fix tray traffic and let 
duty vary; increase steam rates; decrease product 
makes; check feed temperature and quality; check feed 
location.
• A zero product rate could be the result of an incorrect 
product spec, too much heat in the column which 
eliminates internal reflux, or the absence of a heat 
source under a total draw tray to produce needed 
vapour.
Conflicting Specifications
This problem is typically the most difficult to detect and correct. 
Since it is relatively common, it deserves considerable attention.
• You cannot fix all the product flow rates on a tower.
• Avoid fixing the overhead temperature, liquid and vapour 
flow rates because this combination offers only a very 
narrow convergence envelope.
• You cannot have subcooling with a partial condenser.
• A cut point specification is similar to a flow rate spec; you 
cannot specify all flows and leave one unspecified and 
then specify the cut point on that missing flow.
• Only two of the three optional specifications on a pump 
around can be fixed. For example, duty and return 
temperature, duty and pump around rate, and so forth.
• Fixing column internal liquid and vapour flows, as well as 
duties can present conflicts since they directly affect 
each other.
• The bottom temperature spec for a non-reboiled tower 
must be less than that of the bottom stage feed.
• The top temperature for a reboiled absorber must be 
greater than that of the top stage feed unless the feed 
goes through a valve.
• The overhead vapour rate for a reboiled absorber must 
be greater than the vapour portion of the top feed.-199
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-200 References
ww
ThHeat and Spec Error Oscillates
While less common, this situation can also occur. It is often 
caused by poor initial estimates. Check for:
• Water condensation or a situation where water 
alternately condenses and vapourizes.
• A combination of specifications that do not allow for a 
given component to exit the column, causing the 
component to cycle in the column.
• Extremely narrow boiling point separations can be 
difficult since a small step change can result in total 
vapourization. First, change the specifications so that the 
products are not pure components. After convergence, 
reset the specifications and restart.
Equilibrium Error Fails to 
Converge
This is almost always a material balance problem. Check the 
overall balance.
• Check the tower profile. If the overhead condenser is 
very cold for a hydrocarbon-steam column, you need a 
water draw. 
Normally, a side water draw should be added for any 
stage below 200oF.
• If the column almost converges, you may have too many 
water draws.
Equilibrium Error Oscillates
This generally occurs with non-ideal towers, such as those with 
azeotropes. Decreasing the damping factor or using adaptive 
damping should correct this problem.
References
 1 Sneesby, Martin G., Simulation and Control of Reactive Distillation, 
Curtin University of Technology, School of Engineering, March 
1998.
Refer to Section  - 
Parameters Tab for 
more information-200
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Column Operations -201
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Th 2 Henry, Kister., Distillation Design, (1992), pp 497-499.-201
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-202 References
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Th-202
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Electrolyte Operations 3-1
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Th3  Electrolyte 
Operations3-1
3.1  Introduction................................................................................... 2
3.1.1  Adding Electrolyte Operations .................................................... 3
3.2  Crystallizer Operation .................................................................... 4
3.2.1  Design Tab .............................................................................. 6
3.2.2  Rating Tab............................................................................... 9
3.2.3  Worksheet Tab ......................................................................... 9
3.2.4  Dynamic Tab.......................................................................... 10
3.3  Neutralizer Operation .................................................................. 10
3.3.1  Design Tab ............................................................................ 13
3.3.3  Worksheet Tab ....................................................................... 17
3.3.3  Worksheet Tab ....................................................................... 17
3.3.4  Dynamic Tab.......................................................................... 17
3.4  Precipitator Operation ................................................................. 18
3.4.1  Design Tab ............................................................................ 20
3.4.2  Rating Tab............................................................................. 24
3.4.3  Worksheet Tab ....................................................................... 24
3.4.4  Dynamic Tab.......................................................................... 24
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3-2 Introduction
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Th3.1 Introduction
Most HYSYS unit operations can be used when working with the 
OLI Electrolyte property package.
The following HYSYS unit operations are not available in the OLI 
Electrolyte property package:
• Pipe Segment
• Reactors
• Short Cut Column
• Three Phase Distillation
• Compressible Gas Pipe
In addition to the typical HYSYS unit operations, three new 
electrolyte simulations, specific to OLI Electrolyte property 
package have been added. The table below describes the three 
new electrolyte simulations.: 
Press F4 to open the Object Palette. The Object Palette 
shows the unit operations available in OLI Electrolyte 
property package by active icons.
Operation Icon Description
Neutralizer Neutralizer operation is used to control PH 
value for a process material stream.
Precipitator Precipitator operation is used to achieve a 
specified aqueous ionic species concentration 
in its product stream.
Crystalizer Crystallizer operation is used to estimate and 
control solid concentration in a product 
stream.
The electrolyte operations are only available if your case is 
an electrolyte system (the selected fluid package must 
support electrolyte).3-2
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Electrolyte Operations 3-3
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Th3.1.1 Adding Electrolyte 
Operations
There are two ways you can add an electrolyte operation to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Electrolyte Equipment radio button.
3. From the list of available unit operations, select the 
electrolyte operation you want.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Click the Electrolyte Ops icon. The electrolyte object 
palette appears.
3. Double-click the electrolyte operation you want. 
The property view for the selected electrolyte operation 
appears.
The following sections describe the function of each electrolyte 
unit operation.
 Figure 3.1
Electrolyte 
Ops icon3-3
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3-4 Crystallizer Operation
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Th3.2 Crystallizer Operation
The Crystallizer operation models the crystallization of a fully 
defined inlet stream to attain a specified amount of selected 
solids concentration that is present in the effluent. The 
Crystalizer operation contains four tabs: Design, Rating, 
Worksheet, and Dynamics.
Theory
The figure below represents the crystallizer model. A Crystallizer 
has a product stream that contains liquid and solid. By adjusting 
the operation condition like Crystallizer temperature and 
pressure or heat duty, the amount of solid or solid component 
product in the liquid stream can be controlled or estimated.
The Crystallizer vessel is modeled as a perfect mixing in HYSYS. 
Heat can be added or removed from the Crystallizer, and a 
simple constant duty model is assumed.
Boundary Condition
Since the electrolyte flow sheet implements a forward 
calculation only, the Crystallizer does not solve until the Inlet 
Stream is defined. If the energy stream is not specified, the 
crystallizer is treated as an adiabatic one. You must specify two 
 Figure 3.23-4
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Electrolyte Operations 3-5
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Thof the following to define the boundary condition for crystallizer 
solver to proceed:
• T. Crystallizer temperature
• P or DeltP. Crystallizer’s pressure or pressure drop
• E. Heat Duty
• Fcry. Crystal product flow rate (total or a specific 
component)
• Fvap. Vapor flow
Equations
The crystallizer solves under the constraint of mass and energy 
balance equations:
with the target solid equation:
where:  
Fsolid(product stream) = solid flow rate in the outlet liquid 
stream
Fsolid(specified) = desired solid flow rate in the outlet liquid 
stream
E = energy/heat transfer rate
M = mass flow rate
(3.1)
(3.2)
(3.3)
Eproduct stream Evapour stream+ Einlet stream Eduty+=
Mproduct stream Mvapour stream+ Minlet stream=
Fsolid product stream( ) Fsolid specified( )– 0=3-5
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3-6 Crystallizer Operation
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Th3.2.1 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Solver
• User Variables
• Notes
Connections Page
You can specify the inlet stream, outlet stream, and energy 
stream on the Connections page.  
 Figure 3.3
Object Description
Name You can change the name of the operation by typing a new 
name in the field.
Inlet You can enter one or more inlet streams in this table, or 
use the drop-down list to select the streams you want. 
Vapour 
Outlet
You can enter the name of the vapour product stream or 
use the drop-down list to select a pre-defined stream.
Liquid Outlet You can enter the name of the product stream in this field 
or use the drop-down list to select a pre-defined stream. 3-6
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Electrolyte Operations 3-7
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ThParameters Page
On the Parameters page, you can specify the pressure drop and 
solid output flow rate.  
The four radio buttons allow you to control the specified solid 
output in the liquid stream by crystallization operation:
• Mole Flow. Select this radio button to specify the flow 
rate value in mole basis.
• Mass Flow. Select this radio button to specify the flow 
rate value in mass basis.
• Component. Select this radio button to control a 
specified solid component in the operation.
• Total. Select this radio button to control the total solid 
flow rate in the liquid stream.
This page also displays the degrees of freedom for the operation 
at the current setting.
Energy 
(Optional)
You can add an energy stream to the operation by selecting 
an energy stream from the drop-down list or typing the 
name for a new energy stream.
Fluid 
Package
Displays the fluid package currently being used by the 
operation. You can select a different fluid package from the 
drop-down list.
 Figure 3.4
The flow rate of crystal product depends on the solubility of 
the product at the crystallizer’s operation condition. 
Object Description3-7
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3-8 Crystallizer Operation
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ThSolver Page
On the Solver page, you can specify the upper and lower bounds 
of the manipulated variable, the tolerance of specified variable, 
and the maximum iterations/steps of calculations the solver 
performs before stopping.
Crystallizer operates on various boundary conditions. The 
following table lists all the possible options. As soon as the 
operation condition (as listed in the Specified Variables column) 
is known, the crystallizer will start to solve. The Crystallizer 
Calculates column lists some of the calculation variables for the 
operation.
 Figure 3.5
Specified Variables Crystallizer Calculates
Temperature & Pressure Heat Duty, Crystal product flow rate, Vapour 
flow rate
Temperature & Heat 
Duty
Pressure, Crystal product flow rate, Vapor 
flow rate
Temperature & Crystal 
product flow rate
Pressure, Heat Duty, Vapor flow rate
Temperature & Vapour 
flow rate
Pressure, Crystal product flow rate, Heat Duty
Pressure & Heat Duty Temperature, Crystal product flow rate, Vapor 
flow rate
Pressure & Crystal 
product flow rate
Temperature, Heat Duty, Vapor flow rate
Pressure & Vapour flow 
rate
Temperature, Crystal product flow rate, Heat 
Duty3-8
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Electrolyte Operations 3-9
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ThThe bounds for the Manipulated Variables and tolerances for the 
Target Variables are shown on the Solver tab and are user-
modifiable. As well, the Active status for the Manipulated 
Variable used by the solver is shown. However, this flag is meant 
for displaying information only thus cannot be changed.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
3.2.2 Rating Tab
Crystalizer operation currently does not support any rating 
calculations.
3.2.3 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Crystallizer. 
The PF Specs page is relevant to dynamics cases only.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.3-9
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3-10 Neutralizer Operation
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ThThe Crystallizer Worksheet tab also has one extra page called 
the Solids page. On the Solids page, you can view the 
precipitate molar and mass flow rates.
3.2.4 Dynamic Tab
Crystalizer operation currently does not support dynamic mode.
3.3 Neutralizer Operation
The Neutralizer operation models the neutralization of a fully 
defined inlet stream, and allows you to adjust the pH value in 
the effluent stream. The Neutralizer property view contains four 
tabs:
• Design
• Rating
• Worksheet
• Dynamics
 Figure 3.63-10
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Electrolyte Operations 3-11
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ThTheory
The figure below represents the neutralizer model. Through 
adjusting the Reagent Stream variables (flow rate), the PH value 
for the targeting stream (Liquid Stream) could be controlled at 
the level as required.
• Inlet Stream. At least one inlet stream.
• Reagent Stream. Reagent stream must be a free 
stream, that is, not attached to any other unit 
operations.
• Product Stream. A Neutralizer has two product 
streams, a vapour stream and a liquid stream. The liquid 
stream controls the pH value.
• pH. The liquid stream’s pH value that is to be controlled 
must fall in the range between the pH values of the 
Reagent and inlet streams to guarantee the solution.
• Q. The energy stream is optional. When no energy 
stream is attached, an adiabatic operation is assumed.
The Neutralizer vessel is modeled as perfect mixing. Heat can be 
added or removed from the Neutralizer, and a simple constant 
duty model is assumed.
Boundary Condition
Since the electrolyte flow sheet implements a forward 
calculation only, the Neutralizer does not solve until both inlet 
and Reagent streams are defined. 
 Figure 3.73-11
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3-12 Neutralizer Operation
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ThIf the energy stream is not specified, the neutralizer is treated 
as an adiabatic one. If the energy stream is specified, you must 
specify either the Neutralizer temperature or the duty of the 
energy stream. 
Pressure drop of the neutralizer must be specified or can be 
calculated out from the inlet and product streams.
Solving Options
The Neutralizer has two different solving options, depending on 
what you specify.
Option 1 (Targeting pH Value is Not Specified)
If the targeting pH value is not specified, the Neutralizer 
operates as a mixer for the inlet and Reagent streams. The 
product stream accepts the mixed result as is.
Option 2 (Targeting pH Value is Specified)
If the targeting pH value is specified, the flow rate of the 
Reagent stream must be left unspecified. The Reagent stream is 
used as an adjusting variable for neutralizer solver to search for 
a solution to meet the targeting pH value at the outlet stream.
Equations
The Neutralizer solves under the constraint of the following 
equations.
(3.4)
(3.5)
(3.6)
pHproduct stream pHspecified 0=–
pHspecified pHinlet stream pHReagent stream,{ }⊂
Eproduct stream Einlet stream EReagent stream Eduty+ +=3-12
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Electrolyte Operations 3-13
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Thwhere:  
E = energy/heat transfer rate
M = mass flow rate
3.3.1 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Solver
• User Variables
• Notes
Connections Page
You can specify the inlet stream, outlet stream, and energy 
stream on the Connections page.
(3.7)
 Figure 3.8
Mproduct stream Minlet stream MReagent stream+=3-13
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3-14 Neutralizer Operation
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ThParameters Page
On the Parameters page, you can specify the pressure drop and 
an initial pH value. This page also displays the degrees of 
freedom for the operation at the current setting, and the actual 
pH balance in the operation when the operation reaches a 
solution. 
Object Description
Name You can change the name of the operation by typing a new 
name in the field.
Inlet You can enter one or more inlet streams in this table, or 
use the drop-down list to select the streams you want. 
Reagent 
Stream
You can enter a name for the reagent stream or use the 
drop-down list. Reagent stream must be a free stream, that 
is, not attached to any other unit operations.
Vapour 
Outlet
You can type the name of the vapour product stream or use 
the drop-down list to select a pre-defined stream.
Liquid Outlet You can type the name of the product stream in this field or 
use the drop-down list to select a pre-defined stream. 
Energy 
(Optional)
You can add an energy stream to the operation by selecting 
an energy stream from the drop-down list or typing the 
name for a new energy stream.
Fluid 
Package
Displays the fluid package currently being used by the 
operation. You can select a different fluid package from the 
drop-down list.
 Figure 3.93-14
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Electrolyte Operations 3-15
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ThThe pH value in a solution is defined in a mathematical format: 
where:  
[H+] = concentration of H+ in a solution, mol/l
According to Equation (3.5), the pH (specified) value must be 
specified between the pH values of the inlet and the Reagent 
streams. An adjustment of Reagent Stream’s variables, for 
example, temperature, pressure, and compositions, can bracket 
the pH (specified) value to meet the constraint Equation (3.5). 
As soon as the specified pH value is bracketed according to 
Equation (3.5), the pH value of the product stream in 
Equation (3.4) can be obtained by adjusting the flow rate of 
the Reagent stream.
Solver Page
On the Solver page, you can specify the upper and lower bounds 
of the manipulated variable, the tolerance of specified variable, 
and the maximum iterations/steps of calculations the solver 
performs before stopping.
Object Description
Delta P You must specify the pressure drop for the Neutralizer or 
specify inlet and product streams with known pressure.
pH Spec You can specify the product stream’s pH value in this field.
The pH value that is to be controlled must fall in the range 
between the pH values of the Reagent and Inlet Streams for 
calculations to converge. 
(3.8)pH  10 H+[ ]log–=3-15
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3-16 Neutralizer Operation
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ThCurrently only the flow rate of a defined Reagent stream is used 
as an adjustable variable to the solver. Here a defined Reagent 
stream means that the stream can be flashed to get a solution 
with the specified variables meeting the degree of freedom. 
According to HYSYS, a defined stream can have the following 
variables:
• T. Stream Temperature
• P. Stream Pressure
• F. Stream Flow Rate
• x. Stream Component Compositions
• H. Stream Enthalpy
• V. Stream Vapor Fraction
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
 Figure 3.10
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.3-16
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Electrolyte Operations 3-17
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Th3.3.2 Rating Tab
Neutralizer operation currently does not support any rating 
calculations.
3.3.3 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Neutralizer. 
3.3.4 Dynamic Tab
Neutralizer operation currently does not support dynamic mode.
 Figure 3.11
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.3-17
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3-18 Precipitator Operation
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Th3.4 Precipitator Operation
The Precipitator models the precipitation of a selected ion in a 
stream entering the operation to achieve a specified target 
concentration in the effluent stream. The Precipitator operation 
contains four tabs:
• Design
• Rating
• Worksheet
• Dynamics
Theory
The figure below represents the precipitator model. 
Through adjusting the flow rate of the Reagent stream, the 
concentration of the targeting ion could be controlled at the 
desired level as you require in the outlet stream. To ensure that 
the Precipitator functions properly, the ions in the Reagent 
stream must be capable of reacting with the target ion under 
the specified operation condition. The formation of a precipitate 
in the outlet stream reduces the target ion concentration that 
entered the operation in the inlet stream.
• Inlet Stream. At least one inlet stream.
 Figure 3.123-18
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Electrolyte Operations 3-19
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Th• Reagent Stream. Reagent stream must be a free 
stream, that is, not attached to any other unit 
operations.
• Liquid Stream. A Precipitator must have one liquid 
stream (contains liquid and solid) that is a targeting 
stream for the control of ion concentration through 
precipitation.
• Ion Concentration. The product stream’s ion 
concentration value can be controlled by dilution or 
precipitation.
• Q. The energy stream is optional.
The Precipitator is modeled as a perfect mixing in HYSYS. Heat 
can be added or removed from the precipitator through a duty 
stream, and a simple constant duty model is assumed.
Boundary Condition
Since the electrolyte flow sheet implements a forward 
calculation only, the Precipitator does not solve until both inlet 
and Reagent streams are defined. If the energy stream is not 
specified, the precipitator is treated as an adiabatic one. If the 
energy stream is specified, you must specify either the 
Precipitator temperature or the duty of the energy stream. 
Pressure drop of the Precipitator must be either specified or can 
be calculated from the inlet and product streams.
Solving Options
The Precipitator has two different solving options, depending on 
what you specify.
• Option 1 (Targeting Ionic Species Not Specified)
If the targeting ionic species is not specified, the 
Precipitator simply mixes the inlet stream with the 
Reagent stream. The product stream accepts the mixed 
result as is.
• Option 2 (Targeting Ionic Species is Specified)
If the targeting ionic species is specified for the control of 
its concentration, the flow rate of the Reagent stream is 
used as iterative variables for the precipitator solver to 
search for a solution.3-19
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3-20 Precipitator Operation
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ThEquations
The precipitator solves under the constraint of the following 
equations:
where:  
Cion = concentration of the targeting ion species
E = energy/heat transfer rate
M = mass flow rate
3.4.1 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Solver
• User Variables
• Notes
(3.9)
(3.10)
(3.11)
Cion product stream( ) Cion specified( )<
Eproduct stream Evapour stream Eduty+ + Einlet stream EReagent stream+=
Mproduct stream Mvapour stream+ Minlet stream MReagent stream+=3-20
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ThConnections Page
You can specify the inlet stream, outlet stream, and energy 
stream on the Connections page. 
 Figure 3.13
Object Description
Name You can change the name of the operation by typing a new 
name in the field.
Inlet You can enter one or more inlet streams in this table, or 
use the drop-down list to select the streams you want. 
Reagent 
Stream
You can enter a name for the reagent stream or use the 
drop-down list. Reagent stream must be a free stream, that 
is, not attached to any other unit operations.
Vapour 
Outlet
You can enter the name of the vapour product stream or 
use the drop-down list to select a pre-defined stream.
Liquid Outlet You can enter the name of the product stream in this field 
or use the drop-down list to select a pre-defined stream. 
Energy 
(Optional)
You can add an energy stream to the operation by selecting 
an energy stream from the drop-down list or typing the 
name for a new energy stream.
Fluid 
Package
Displays the fluid package currently being used by the 
operation. You can select a different fluid package from the 
drop-down list.3-21
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3-22 Precipitator Operation
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ThParameters Page
On the Parameters page, you can specify the pressure drop, 
select the ion to be controlled, and specify the ion concentration 
in the liquid stream. This page also displays the degrees of 
freedom for the operation at the current setting, and the actual 
ion concentration value in the operation when the operation has 
reached a solution. 
 Figure 3.14
Object Description
Delta P You must specify the pressure drop for the Precipitator or 
specify inlet and product streams with known pressure.
Controlled 
Ion
Select the ion component you want to control from the 
drop-down list, or type the name of the ion component in 
the field.
Ion Spec The concentration of ion from the inlet stream can be 
controlled via the following exercises:
• Dilution. If the mixing of reagent and inlet streams 
does not produce the ion to be controlled and the ion 
concentration in the Reagent stream is less than that 
in the inlet stream, an increase of flow rate of the 
Reagent stream can achieve the target. In this case, 
the Chemistry Model does not have to include Solid.
• Precipitation. Form precipitator by mixing inlet and 
Reagent streams. The change of Regent stream 
variables: temperature, pressure, flow rate or 
composition may achieve the target. To form 
precipitator, OLI chemistry model must include Solid. 3-22
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ThSolver Page
On the Solver page, you can specify the upper and lower bounds 
of the manipulated variable, the tolerance of specified variable, 
and the maximum iterations/steps of calculations the solver 
performs before stopping. 
Currently, the flow rate of the Reagent stream is the 
manipulated variable used by the precipitator solver to search 
for a solution.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
 Figure 3.15
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.3-23
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3-24 Precipitator Operation
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Th3.4.2 Rating Tab
Precipitator operation currently does not support any rating 
calculations.
3.4.3 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Precipitator. 
3.4.4 Dynamic Tab
Precipitator operation currently does not support dynamic mode.
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.3-24
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Heat Transfer Operations 4-1
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Th4  Heat Transfer 
Operationsw.cadfamily.com    EMa
e document is for study 4.1  Air Cooler....................................................................................... 3
4.1.1  Theory.................................................................................... 3
4.1.2  Air Cooler Property View............................................................ 8
4.1.3  Design Tab .............................................................................. 8
4.1.4  Rating Tab............................................................................. 10
4.1.5  Worksheet Tab ....................................................................... 12
4.1.6  Performance Tab .................................................................... 12
4.1.7  Dynamics Tab ........................................................................ 13
4.1.8  HTFS - ACOL Tab.................................................................... 16
4.2  Cooler/Heater.............................................................................. 45
4.2.1  Theory.................................................................................. 45
4.2.2  Heater or Cooler Propety View ................................................. 47
4.2.3  Design Tab ............................................................................ 48
4.2.4  Rating Tab............................................................................. 50
4.2.5  Worksheet Tab ....................................................................... 52
4.2.6  Performance Tab .................................................................... 53
4.2.7  Dynamics Tab ........................................................................ 56
4.3  Fired Heater (Furnace) ................................................................ 62
4.3.1  Theory.................................................................................. 64
4.3.2  Fired Heater Property View ...................................................... 71
4.3.3  Design Tab ............................................................................ 72
4.3.4  Rating Tab............................................................................. 75
4.3.5  Worksheet Tab ....................................................................... 82
4.3.6  Performance Tab .................................................................... 82
4.3.7  Dynamics Tab ........................................................................ 874-1
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4-2 Heat Transfer Operations 
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The document is for study 4.4  Heat Exchanger ............................................................................89
4.4.1  Theory ..................................................................................90
4.4.2  Heat Exchanger Property View ..................................................94
4.4.3  Design Tab .............................................................................95
4.4.4  Rating Tab............................................................................108
4.4.5  Worksheet Tab......................................................................125
4.4.6  Performance Tab ...................................................................125
4.4.7  Dynamics Tab.......................................................................130
4.4.8  HTFS-TASC Tab.....................................................................138
4.5  LNG.............................................................................................163
4.5.1  Theory ................................................................................164
4.5.2  LNG Property View ................................................................168
4.5.3  Design Tab ...........................................................................169
4.5.4  Rating Tab............................................................................179
4.5.5  Worksheet Tab......................................................................186
4.5.6  Performance Tab ...................................................................186
4.5.7  Dynamics Tab.......................................................................193
4.5.8  HTFS-MUSE Tab....................................................................200
4.6  References..................................................................................2164-2
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Heat Transfer Operations 4-3
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Th4.1 Air Cooler
The Air Cooler unit operation uses an ideal air mixture as a heat 
transfer medium to cool (or heat) an inlet process stream to a 
required exit stream condition. One or more fans circulate the 
air through bundles of tubes to cool process fluids. The air flow 
can be specified or calculated from the fan rating information. 
The Air Cooler can solve for many different sets of specifications 
including the: 
• Overall heat transfer coefficient, UA
• Total air flow
• Exit stream temperature
4.1.1 Theory
Steady State
The Air Cooler uses the same basic equation as the Heat 
Exchanger unit operation; however, the Air Cooler operation can 
calculate the flow of air based on the fan rating information.
The Air Cooler calculations are based on an energy balance 
between the air and process streams. For a cross-current Air 
Cooler, the energy balance is calculated as follows:
where:  
Mair = air stream mass flow rate
Mprocess = process stream mass flow rate
H = enthalpy
Mair(Hout - Hin)air = Mprocess(Hin - Hout)process (4.1)4-3
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4-4 Air Cooler
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ThThe Air Cooler duty, Q, is defined in terms of the overall heat 
transfer coefficient, the area available for heat exchange, and 
the log mean temperature difference:
where:  
U = overall heat transfer coefficient
A = surface area available for heat transfer
 = log mean temperature difference (LMTD)
Ft = correction factor
The LMTD correction factor, Ft, is calculated from the geometry 
and configuration of the Air Cooler.
ACOL Functionality
In Steady State mode, you can also access certain ACOL 
functions on the HTFS-ACOL tab.
You must install and license ACOL 6.4 before you can access the 
ACOL functions.
Dynamic
In dynamics, the Air Cooler tube is capable of storing inventory 
like other dynamic unit operations. The direction of the material 
flowing through the Air Cooler operation is governed by the 
pressures of the surrounding unit operations.
Heat Transfer
The Air Cooler uses the same basic energy balance equations as 
the Heat Exchanger unit operation. The Air Cooler calculations 
are based on an energy balance between the air and process 
streams. 
(4.2)Q UAΔTLMFt–=
ΔTLM4-4
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ThFor a cross-current Air Cooler, the energy balance is shown as 
follows:
where:  
Mair = air stream mass flow rate
Mprocess = process stream mass flow rate
 = density
H = enthalpy
V = volume of Air Cooler tube
Dynamic Specifications
HYSYS requires three overall specifications in order for the Air 
Cooler unit operation to fully solve in Dynamic mode:
(4.3)
Dynamic 
Specifications
Description
Overall UA The Overall UA is the product of the Overall Heat 
Transfer Coefficient (U) and the total area available for 
heat transfer (A). You can specify the value of UA on 
the Parameters page of the Design tab.
Mprocess Hin Hout–( )process Mair Hin Hout–( )air– ρ
d VHout( )process
dt
---------------------------------------=
ρ
4-5
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4-6 Air Cooler
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ThFan Rating 
Information
The Fan Rating information characterizes the flow rate 
and cooling properties of the air flowing through the Air 
Cooler. HYSYS provides two methods to determine the 
Fan Rating information.
For the Air Cooler Simple Design method, specify 
the following variables in the Sizing page of the Rating 
tab: 
• Demanded Speed
• Design Speed
• Design Flow
• Max Acceleration (optional)
For the ACOL Design method, specify:
•  The Air Mass Flow Rate variable in the Sizing 
page of the Rating tab
• The various Fan parameters in the HTFS - ACOL 
tab
Pressure Drop HYSYS provides two options to determine the pressure 
difference between the inlet and outlet process 
streams:
• Specified pressure drop (constant value)
• Calculated pressure drop from K-value (value may 
vary with time)
These pressure drop specifications can be made on the 
Specs page of the Dynamics tab.
Dynamic 
Specifications
Description4-6
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Heat Transfer Operations 4-7
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ThPressure Drop
The pressure drop of the Air Cooler can be determined in one of 
two ways:
• Specify the pressure drop. This method assumes the 
pressure difference between the inlet process stream and 
outlet process stream is constant. This method is 
applicable to both Steady State and Dynamic modes.
• Define a pressure flow relation in the Air Cooler by 
specifying a k-value. This method assumes the 
pressure difference between the inlet process stream and 
outlet process stream varies with time. This method is 
applicable only to Dynamic mode.
If the pressure flow option is chosen for pressure drop 
determination in the Air Cooler, a k-value is used to relate the 
frictional pressure loss and flow through the exchanger. This 
relation is similar to the general valve equation:
The general flow equation uses the pressure drop across the 
Heat Exchanger without any static head contributions. The 
quantity, P1 - P2, is defined as the frictional pressure loss which 
is used to “size” the Air Cooler with a k-value.
Using the pressure flow option, you must have an accurate k-
value to generate valid/accurate results.
HYSYS also provides a feature than enables you to calculate the 
k-value of the Air Cooler at steady state. This k-value can then 
be used in Dynamic mode to calculate the varying pressure 
difference between the inlet and outlet process streams.
The following information is required for HYSYS to calculate the 
k-value in Steady State mode:
• Completely defined inlet or outlet process stream (to 
obtain the flow and density variable value)
• Pressure difference between the inlet and outlet stream
• Solved Air Cooler operation
HYSYS assumes no pressure difference in the air flowing 
(4.4)flow density k× P1 P2–=
The Calculate K option is 
located in the Air Cooler 
property view, Dynamics 
tab, Specs page.4-7
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4-8 Air Cooler
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Ththrough the Air Cooler operation.
4.1.2 Air Cooler Property View
To add an Air Cooler to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar (or press F12). The UnitOps property view 
appears.
2. Click the Heat Transfer Equipment radio button.
3. From the list of available unit operations, select Air Cooler.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar 
(or press F4). The Object Palette appears.
2. Double-click the Air Cooler icon. 
The Air Cooler property view appears.
4.1.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
Air Cooler icon4-8
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ThConnections Page
On the Connections page, you can specify the feed and product 
streams attached to the Air Cooler. You can change the name of 
the operation in the Name field.
Parameters Page
On the Parameters page, the following information appears: 
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Parameters Description
Air Cooler Model Allows you to select HYSYS-Engines or HTFS-Engines. 
The HTFS-Engines options appears only if you have 
ACOL6.4 installed and licensed. The HTFS-Engines 
option allows you to access ACOL functions on the 
HTFS-ACOL tab.
Process Stream 
Delta P
Allows you to specify the pressure drops (DP) for the 
process stream side of the Air Cooler. The pressure 
drop can be calculated if both the inlet and exit 
pressures of the process stream are specified. There is 
no pressure drop associated with the air stream. The 
air pressure through the Cooler is assumed to be 
atmospheric.
Overall UA Contains the value of the Overall Heat Transfer 
Coefficient multiplied with the Total Area available for 
heat transfer. The Air Cooler duty is proportional to the 
log mean temperature difference, where UA is the 
proportionality factor. The UA can either be specified or 
calculated by HYSYS.
Configuration Displays the possible tube pass arrangements in the 
Air Cooler. There are seven different Air Cooler 
configurations to choose from. HYSYS determines the 
correction factor, Ft, based on the selected Air Cooler 
configuration.
Air Intake/
Outlet 
Temperatures
The inlet and exit air stream temperatures can be 
specified or calculated by HYSYS.
Air Intake 
Pressure
The inlet air stream pressure has a default value of 1 
atm.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.4-9
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4-10 Air Cooler
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ThNotes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation or 
the simulation case in general. 
4.1.4 Rating Tab
The Rating tab allows you to specify the fan rating information. 
The steady state and dynamic Air Cooler operations share the 
same fan rating information.
The Rating tab contains the following pages:
• Sizing page. The content of this page differs depending 
on which option you selected in the Air Cooler Model 
drop-down list on the Parameters page of the Design tab. 
If you selected HTFS-Engines, this page displays only 
one field: Air Mass Flow Rate.
• Nozzles page. This page appears only if the HYSYS 
Dynamics license is activated.
Sizing Page HYSYS-Engines
In the Sizing page, the following fan rating information appears 
for the Air Cooler operation when the HYSYS-Engines option is 
selected on the Parameters page of the Design tab. 
In dynamics, the air flow must be calculated using the fan 
rating information.
Fan Data Description
Number of 
Fans
Number of fans in the Air Cooler.
Speed Actual speed of the fan in rpm (rotations per minute).
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.4-10
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Heat Transfer Operations 4-11
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ThThe air flow through the fan is calculated using a linear relation: 
In dynamic mode only, the actual speed of the fan is not always 
equal to the demanded speed. The actual fan speed after each 
integration time step is calculated as follows:
Each fan in the Air Cooler contributes to the air flow through the 
Cooler. The total air flow is calculated as follows:
Demanded 
speed
Desired speed of the fan. 
• Steady State mode. The demanded speed is always 
equal the speed of the fan. The desired speed is either 
calculated from the fan rating information or user-
specified.
• Dynamic mode. The demanded speed should either be 
specified directly or from a Spreadsheet operation. If a 
control structure uses the fan speed as an output 
signal, it is the demanded speed which should be 
manipulated.
Max 
Acceleration
Applicable only in Dynamic mode. It is the rate at which the 
actual speed moves to the demanded speed.
Design speed The reference Air Cooler fan speed. It is used in the 
calculation of the actual air flow through the Cooler.
Design air 
flow
The reference Air Cooler air flow. It is used in the 
calculation of the actual air flow through the Cooler.
Current air 
flow
This can be calculated or user-specified. If the air flow is 
specified no other fan rating information needs to be 
specified.
Fan Is On By default, this checkbox is selected. You have the option 
to turn on or off the air cooler as desired. When you clear 
the checkbox, the temperature of the outlet stream of the 
air cooler will be identical to that of the inlet stream.
The Fan Is On checkbox has the same function as setting 
the Speed to 0 rpm.
(4.5)
(4.6)
(4.7)
Fan Data Description
Fan Air Flow Speed
Design Speed
------------------------------------ Design Flow×=
Actual Speed Max Acceleration( )Δt Actual Speedo 
until Actual Speed
+
Demanded Speed
=
=
Total Air Flow Fan Air Flow∑=4-11
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4-12 Air Cooler
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ThSizing Page HTFS-Engines
The Sizing page for HTFS Engines appears when the HTFS-
Engines option is selected on the Parameters page of the Design 
tab. 
HYSYS air coolers can have multiple fans, and HYSYS calculates 
the airflow from the sum of the airflows of each fan.  
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. The information provided in the 
Nozzles page is applicable only in Dynamic mode. 
4.1.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Air Cooler. 
4.1.6 Performance Tab
The Performance tab contains pages that display the results of 
the Air Cooler calculations.
In HTFS-Engines option, you can only enter the total air 
mass flow rate for the air cooler.
The PF Specs page is relevant to dynamics cases only.
The Profiles page is relevant to dynamics cases only.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.4-12
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ThResults Page
The information from the Results page is shown as follows:
4.1.7 Dynamics Tab
The Dynamics tab contains the following pages:
• Model
• Specs
• Holdup
• Stripchart
Results Description
Working Fluid 
Duty
This is defined as the change in duty from the inlet to 
the exit process stream:
LMTD Correction 
Factor, Ft
The correction factor is used to calculate the overall 
heat exchange in the Air Cooler. It accounts for 
different tube pass configurations.
UA The product of the Overall Heat Transfer Coefficient, 
and the Total Area available for heat transfer. The UA 
can either be specified or calculated by HYSYS.
LMTD The LMTD is calculated in terms of the temperature 
approaches (terminal temperature difference) in the 
exchanger, using the following uncorrected LMTD 
equation:
where: 
Inlet/Outlet 
Process 
Temperatures
The inlet and outlet process stream temperatures can 
be specified or calculated in HYSYS.
Inlet/Outlet Air 
Temperatures
The inlet and exit air stream temperatures can be 
specified or calculated in HYSYS.
Air Inlet 
Pressure
The inlet air stream pressure has a default value of 1 
atm.
Total Air flow The total air flowrate appears in volume and mass 
units.
Hprocess in, Duty+ Hprocess out,=
ΔTLM
ΔT1 ΔT2–
ΔT1 ΔT2( )⁄( )ln
--------------------------------------=
ΔT1 Thot out, Tcold in,–=
ΔT2 Thot in, Tcold o, ut–=4-13
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4-14 Air Cooler
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ThIn dynamics, the air flow must be calculated using the fan rating 
information.
Model Page
The Model page allows you to define how UA is defined in 
Dynamic mode. The value of UA is calculated as follows:
where:  
UAsteadystate = UA value entered on the Parameters page of 
the Design tab.
The Model page contains the UA Calculation group. which 
contains four fields:
If you are working exclusively in Steady State mode, you are 
not required to change any of the values on the pages 
accessible through this tab. 
(4.8)
 
(4.9)
f1 = (mass flowrate / reference flowrate)^0.8   for air (4.10)
f2 = (mass flowrate / reference flowrate)^0.8   for fluid (4.11)
Field Description
UA The steady state value of UA. This should be the same 
as the value entered on the Parameters tab.
Reference air 
flow
The reference flowrate for air. It is used to calculate the 
value of f1 as shown in Equation (4.10).
Reference fluid 
flow
The reference flowrate for the fluid. It is used to 
calculate the value of f2 as shown in Equation (4.11).
Minimum flow 
scale factor
The minimum scale factor used. If the value calculated 
by Equation (4.9) is smaller than this value, this 
value is used.
UAdynamic F UAsteadystate×=
F 2 f1 f2××
f1 f2+( )
-------------------------= the flow scale factor4-14
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ThSpecs Page
The Specs page contains information regarding the calculation 
of pressure drop across the Air Cooler. You can specify how the 
pressure drop across the Air Cooler is calculated in the Dynamic 
Specifications group.
The Dynamic Parameters group contains information about the 
Dynamic 
Specifications
Description
Overall Delta P A set pressure drop is assumed across the valve operation 
with this specification. The flow and the pressure of either 
the inlet or exit stream must be specified or calculated from 
other operations in the flowsheet. The flow through the 
valve is not dependent on the pressure drop across the Air 
Cooler. To use the overall delta P as a dynamic specification, 
select the corresponding checkbox.
The Air Cooler operations, like other dynamic unit 
operations, should use the k-value specification option as 
much as possible to simulate actual pressure flow relations 
in the plant.
Overall k Value The k-value defines the relationship between the flow 
through the Air Cooler and the pressure of the surrounding 
streams. You can either specify the k-value or have it 
calculated from the stream conditions surrounding the Air 
Cooler. You can “size” the Cooler with a k-value by clicking 
the Calculate K button. Ensure that there is a non zero 
pressure drop across the Air Cooler before the Calculate K 
button is clicked. To use the k-value as a dynamic 
specification, select the corresponding checkbox.
Pressure Flow 
Reference Flow
The reference flow value results in a more linear 
relationship between flow and pressure drop. This is used 
to increase model stability during startup and shutdown 
where the flows are low.
If the pressure flow option is chosen the k value is 
calculated based on two criteria. If the flow of the system is 
larger than the k Reference Flow the k value remains 
unchanged. It is recommended that the k reference flow is 
taken as 40% of steady state design flow for better 
pressure flow stability at low flow range. If the flow of the 
system is smaller than the k Reference Flow the k value is 
given by:
where Factor is determined by HYSYS internally to take into 
consideration the flow and pressure drop relationship at low 
flow regions.
kused kspecified Factor×=4-15
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4-16 Air Cooler
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Thholdup of the Air Cooler, which is described in the table below.
Holdup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
The Zone drop-down list enables you to select and view the 
holdup data for each zone in the operation.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
4.1.8 HTFS - ACOL Tab
This tab allows you to access certain ACOL functions. To access 
the functions on this tab, you must do the following:
• Install and license ACOL6.4.
• Select HTFS-Engines from the Air Cooler Model drop-
down list on the Parameters page of the Design tab.
The HTFS-Engines option runs only in Steady State mode.
Dynamic Parameters Description
Fluid Volume Specify the Air Cooler holdup volume.
Mass Flow The mass flow of process stream through the Air 
Cooler is calculated.
Exit Temperature The exit temperature of the process stream.
The Air Cooler operation only has one zone.
If you provide more data than is required, ACOL will perform 
consistency checks and warn you of any discrepancies.
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Zone 
Information section for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab for 
more information.
For more information 
about ACOL data input, 
refer to the ACOL 
Reference Guide.
Also, refer to the ACOL 
Online Help for information 
about specific input fields.4-16
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ThACOL Simulation Modes
ACOL has eight different simulation modes, four of which are 
recognized by HYSYS. Each mode calculates a different variable 
based on the data you supply. HYSYS checks the data entered 
for the air-cooler to determine if ACOL can run, then which 
mode ACOL will run based on the supplied data. HYSYS then 
sends the data to ACOL.
The following tables list and describe the criteria used by HYSYS 
to determine the air cooler status messages, whether or not 
ACOL can run, and which mode ACOL will run.
All simulation modes
The following applies unless specified differently:
ACOL Simulation 9
Calculation of the outlet temperature:
Criteria Value
Air inlet temperature specified
Air outlet temperature not specified
Pressure drop not specified
Process inlet temperature specified
Process outlet temperature not specified
Criteria Value
Process inlet temperature specified
Process outlet temperature not specified
Airflow specified
Process flow rate specified4-17
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4-18 Air Cooler
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ThACOL Simulation 1
Calculation of the inlet temperature:
ACOL Simulation 3
Calculation of the process mass flow rate:
ACOL Simulation 4
Calculation of the air mass flow rate:
Importing and Exporting ACOL Input 
Files
Import and Export buttons appear on every page of the HTFS-
Criteria Value
Process inlet temperature not specified
Process outlet temperature specified
Airflow specified
Process flow rate specified
Process inlet temperature not specified
Process outlet temperature specified
Criteria Value
Process inlet temperature specified
Process outlet temperature specified
Airflow specified
Process flow rate not specified
Criteria Value
Process inlet temperature specified
Process outlet temperature specified
Airflow not specified
Process flow rate specified4-18
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Heat Transfer Operations 4-19
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ThACOL tab. These buttons allow you to import existing ACOL data 
or export the current data. The file format used is ACOL Input 
files [*.aci].
Bundle Geometry Page
The Bundle Geometry page content changes depending on the 
radio button you select.
Headers/Nozzles Radio Button
 Figure 4.14-19
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ThThe following table describes the fields that appear when you 
click the Headers/Nozzles radio button.
Object Description
Number of Inlet 
Nozzles
Enter the number of inlet nozzles per bundle. Too 
few nozzles can cause excessive pressure losses 
and possibly erosion of the nozzles and headers. 
Default value is 1.
Number of Outlet 
Nozzles
Enter the number of outlet nozzles per bundle. If a 
phase change occurs through the bundle then it 
may be appropriate to have a different number of 
nozzles of different size to the inlet nozzles. 
Default value is 1.
Inside Diameter of 
Inlet Nozzle
Enter the inside diameter of the inlet nozzles. 
Defaults to the highest preferred diameter which 
gives a momentum flux (rV2) less than 6000 kg/m 
s2. Preferred sizes are; 50 mm, 100 mm, 150 mm, 
200 mm, and so forth.
Inside Diameter of 
Outlet Nozzle
Enter the inside diameter of the outlet nozzles. 
Defaults to the highest preferred diameter which 
gives a momentum flux (rV2) less than 6000 kg/m 
s2. Preferred sizes are; 50 mm, 100 mm, 150 mm, 
200 mm, and so forth.
Type of Header Type of Header options: Box, D-header, Plug, 
Cover Plate, or Manifold.
U-Bend 
Configuration
U-Bend Configuration options: No-bends, U-bends 
in alternate passes, or U-bends in every pass.
Depth of Inlet 
Header
Enter the depth of the header at the tubeside fluid 
inlet. For a D-header, this will be the maximum 
depth of the D-section. Default is 300mm (11.8 in) 
for Air-cooled Heat Exchangers.
Depth of Other 
Header
Enter the depth of the other header. The other 
header is at the side opposite to the inlet header. 
For an odd number of passes, this will be the 
outlet header. For a D-header, the depth will be 
the maximum depth of the D-section. Default is 
150mm (5.9 in) for Air-cooled Heat Exchangers.
Perf. Pass Plates Enter the average number of velocity heads lost 
through each perforated plate in the headers. 
Perforated pass plates are usually fitted to 
strengthen the header in high-pressure 
applications. Default value is 0.04-20
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Heat Transfer Operations 4-21
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ThBundle Radio Button
The following table describes the fields that appear when you 
click the Bundle radio button.
 Figure 4.2
Object Description
Number of 
Passes
Required. Must be <= 50. With four or more number 
of passes, the exchanger tends towards the ideal of a 
pure counter current or co-current exchanger.
Number of Rows Required. Must be <= 100.
Number of Tubes Required. Must be < 1000.
Type of Bundle There are five types of bundle layouts available from 
the drop-down list; the bundle layout affects the 
allowable number of tubes.
NumberOfTubesInARow = NumberOfTubes/
NumberOfRows
If the NumberOfTubesInARow does not have a 
remainder, then only these bundles can be used:
• Inline
• Staggered - even rows to the right
• Staggered - even rows to the left
If the NumberofTubesInARow has a remainder, then 
only two bundles can be used:
• Staggered - extra tubes in odd rows
• Staggered - extra tube in even rows
Tube Side Flow 
Orientation
Select the orientation of the tubeside flow with respect 
to the X-side flow. This item is used only to correctly 
set up a symmetrical bundle. It does not apply to a 
non-symmetrical bundle as the tubeside flow 
orientation is explicitly set when the bundle is defined 
using the Pass Layout Window.
Select from Counter-current (default), Cross-flow, Co-
current4-21
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4-22 Air Cooler
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ThRows per Pass Enter the number of tube rows occupied by each 
tubeside pass. Only to be used when specifying 
symmetrical bundles. When specifying non-
symmetrical bundles use the Pass Layout Window to 
specify the bundle.
Max. No. Tubes 
per Row per Pass
Enter the maximum number of tubes in each row 
occupied by each pass. Only to be used when 
specifying symmetrical bundles. When specifying non-
symmetrical bundles use the interactive bundle 
specification feature.
X-Side Stream 
Mass Flow 
Orientation
Defines the X-side flow orientation relative to the 
Bundle direction. Enter 0 (vertical-up), 45, 90 
(horizontal) or 180 (vertical-down). Default value is 0.
Bundle Relative 
Direction
Defines the angle of orientation of the bundle relative 
to the X-side Stream Mass Flow Direction (XSFD) in the 
range -90° to +90°. If 0° (default) is entered the tubes 
are always horizontal regardless of the X-side Stream 
Mass Flow Direction.
Number of 
Circuits
Enter the number of times a basic pass layout pattern 
appears in the bundle.
The repeat facility is used when a basic pass layout 
pattern is to be repeated a number of times across the 
bundle. This feature is most likely to be of use in air-
conditioning coils with U tube circuits. It may only be 
used:
a) with inline bundles and staggered bundles with the 
same number of tubes per row or,
b) when X-side stream inlet conditions do not vary 
across the bundle.
When using the repeat facility, count the original 
section as 1 (Default).
Shape of Tubes Select from Round (default), Oval, or Flat. If Oval or 
Flat tubes are selected, the geometric data for the tube 
should be entered for each tube type on the Non-
circular Tubes page (click the Tubes radio button).The 
geometric data for each fin type can be entered on the 
Extended Surfaces page.
Pass Layout 
Diagram button
Displays a Pass Layout diagram that allows you to 
specify the pass arrangement according to your 
requirements.
Object Description4-22
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Heat Transfer Operations 4-23
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ThTubes Radio Button
The following table lists and describes the fields that appear 
when you click the Tubes radio button.
 Figure 4.3
Object Description
Common Options
Add Tube button Adds a tube to the air cooler.
Remove Tube button Removes a tube from the air cooler.
Effective Length This is the length of tube that is transferring heat. 
Inactive parts of a tube are where it fits into the 
tubesheets and comes into contact with tube 
supports. Include these parts in the Total Tube 
Length. Default is 6000mm (19.7 ft) for Air-cooled 
Heat Exchangers.
Total Length This is the total length of tube including the ends 
fitted into the tubesheets and where the tube 
comes into contact with tube supports.This is used 
for tubeside pressure drop calculations only. 
Default value is the Effective tube length.
Transverse Pitch This is the distance between the centre-lines of 
consecutive tubes in the same tube row. Default is 
2.3 times Tube OD for Air-cooled Heat Exchangers4-23
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4-24 Air Cooler
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ThLongitudinal Pitch If you have a standard TEMA tube layout, for 
example triangular (30°), rotated square (45°), 
rotated triangular (60°), or square (90°), then use 
the layout angle.
If you have a non-standard tube layout then use 
this item. The plain tube correlations are only valid 
for the standard TEMA tube layout given above so 
use layout angle in this case.
For uncommonly large longitudinal pitches, you 
may have to allow for a reduction in the heat 
transfer coefficient separately from ACOL. 
Currently ACOL does not allow for this effect.
There is no default value. The value will be 
calculated from the Transverse Pitch and the 
Layout Angle.
Layout Angle Use this field to enter the layout angle for a 
standard TEMA tube layout.
• 30° – triangular arrangement (default)
• 45° – rotated square arrangement
• 60° – rotated triangular arrangement
• 90° – square arrangement (for in-line banks 
only)
If you have a non-standard tube layout, in other 
words one, which would give a layout angle not in 
the above list then, input longitudinal pitch instead 
of this item. Use this item for plain tubes, as the 
correlations are only valid for the standard TEMA 
tube layouts. Default Value is 30°.
Tube Details group options
Tube Number Displays the system defined tube number.
If you have more than one tube type defined, then 
corresponding input cells appear on the Extended 
Surfaces and Materials pages.
Tube ID Up to 4 Tube Diameters may be specified.
Default values for Tube ID(1): Tube ID(1) = Tube 
OD(1) – 3.3mm (0.13in) for Air-cooled Heat 
Exchangers. Other tube types default to Tube 
ID(1).
Tube OD Up to 4 Tube Diameters may be specified. API661 
recommends 25.4 mm or 1 inch as the minimum 
outside diameter.
Non-Circular Tube Details group options
Non-Circular Tubes 
checkbox
Select this checkbox to specify non-circular tube 
parameters. When you click this checkbox, the 
fields listed below appear.
Tube Number Displays the system defined tube number.
Major Axis on 
Outside of Tube
Allows you to specify the length of the flatter side 
of the tube.
Object Description4-24
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Heat Transfer Operations 4-25
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ThExtended Surfaces Page 
The following table lists and describes the objects on this page. 
Minor Axis on 
Outside of Tube
Allows you to specify the length of ‘short’ side of 
the tube.
Tube Wall Thickness Allows you to specify the tube wall thickness.
 Figure 4.4
Object Description
Add Fin Click this button to add a fin. The fin parameter set 
appears in the Fin Details table.
If you have finned tubes, you will need to supply tube 
and fin details on the Bundle Geometry and Extended 
Surfaces pages.
Remove Fin Click this button to remove the select fin parameter 
set.
Fin ID Displays the system generated Fin number.
Fin Type Allows you to select a fin type from a drop-down list:
• Integral
• G-fin (embedded) 
(default)
• Modified G-fin 
• L-finned 
• Bi-metallic or extruded
• Shoulder-grooved
• Tube-in-plate 
• Plain tubes
• Serrated fins
• Low fins
• Circular studs
• Rectangular studs
• Elliptical studs
• Lenticular studs
• Chamfered studs
Object Description4-25
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4-26 Air Cooler
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ThTip Diameter or 
Plate Length
For a finned or studded tube, enter the fin (or stud) tip 
diameter. Default is 2.25 times Tube OD for Air-cooled 
Heat Exchangers.
For tube-in-plate fins, enter the plate length in the 
direction of the X-side flow (from the leading edge to 
the trailing edge of the plate). This will be calculated if 
left blank.
Frequency This is the number of fins per unit length or the 
number of stud crowns per unit length. Default is 433 
fins/m (11 fins/inch) for Air-cooled Heat Exchangers.
Mean Fin 
Thickness
For fins made by wrapping ribbon around the base 
tube, the fin thickness is usually thinner than the 
ribbon thickness. Default is 0.28mm (0.011in) for Air-
cooled Heat Exchangers
Fin Root 
Diameter
Enter the root diameter for Integral, L-finned, Extruded 
tubes or Shoulder-grooved fins. For other fin types, the 
fin root diameter is the base tube outside diameter. 
The Common Fin Root Diameter applies to the whole 
bundle unless a local values is used. Defaults to the 
tube outside diameter.
Number of Studs 
per Crown
This is the number of studs making up a crown.
Stud Width This item is not required for circular studs.
Major Axis of Fin This is the length of the ‘long’ side of the tube. Default 
is 54 mm (2.13 in).
Minor Axis of Fin This is the length of the ‘short’ side of the tube. Default 
value is 34 mm (1.34 in).
Fin Root 
Thickness
For L shape or bimetallic fins. Fin Root Thickness is 
used in place of Fin Root Diameter for round fins. 
Default value is 0.0.
Object Description4-26
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Heat Transfer Operations 4-27
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ThACHE Geometry Page 
The following table lists and describes some of the objects on 
the ACHE Geometry page. 
 Figure 4.5
Object Description
Number of Bays 
per Unit
Required. Range 1-99. Default is 1.
Number of 
Bundles per Bay
Required. Range 1-12. Default is 1.
Number of Fans 
per Bay
Required. Range 1-6. Default is 2.
Fan 
Configuration
Select from Forced Draught, Induced Draught, or No 
fans.
Type of Louvres Select the type of louvres required for the air cooler. 
Options appear in the image to the left.
Louvre Angle or 
Loss Coefficient
Enter either the louvre opening angle (for louvre types 
A-D) or the loss coefficient (for louvre type K).
An angle of 0° is fully open and 90° is fully closed.
Steam Coils Select Yes or No (default) depending on whether a 
steam coil is fitted. This item is used only in the 
calculation of the X-side pressure drop. Steam coils are 
assumed to consist of one row of tubes with the same 
tube geometry as the first type of fin but with twice the 
transverse pitch.
Plenum Depth This is distance from the bundle side of the fan ring to 
the bundle. Defaults to 0.4 times the exchanger fan 
diameter.4-27
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4-28 Air Cooler
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ThProcess Data Page
HYSYS uses information in the first six fields to determine if 
ACOL can run, and what mode it will use.  
Ground 
Clearance
This is the distance from the ground to the fan inlet for 
a forced draught exchanger or to the bundle entry for 
an induced draught exchanger. Defaults to1.5 times 
the exchanger fan diameter.
Height Above 
Bundle
This is the distance from the top of the bundle to the 
exchanger exit. Use only with the Natural Convection 
simulation option. The hardware height acts as a 
'chimney' filled with hot air.
For forced draught exchangers this will typically be the 
height of a wind skirt above the bundle. For induced 
draught exchangers it will be the distance to the top of 
the fan casing.
Default value is 0.0.
Exchanger Fan 
Diameter
This is used to calculate fan related pressure losses 
and fan noise levels. The fan diameter cannot be larger 
than the bay width. Default calculated to give 40% 
bundle coverage per fan.
A or V Frame The default is (None).
 Figure 4.6
You cannot edit the values in black text. These values are 
determined using input on other tabs in the Air Cooler 
property view.
Object Description
Refer to ACOL 
Simulation Modes 
section for more 
information.4-28
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Heat Transfer Operations 4-29
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ThThe following table lists and describes the objects on this page.
Object Description
Process Steams group
Total Mass Flow Displays the process stream mass flow calculated 
by HYSYS.
Inlet Mass Quality Displays the default value.
Outlet Mass Quality Displays the system defined outlet mass quality.
Inlet Temperature Displays the stream inlet temperature as defined 
on the Worksheet tab.
Outlet Temperature Displays the stream outlet temperature, if 
available.
Inlet Pressure Displays the stream inlet pressure as defined on 
the Worksheet tab.
Heat Load You may enter the heat load directly, or omit it and 
leave ACOL to calculate it from the stream 
flowrate and inlet and outlet conditions.
ACOL will use the input heat load to calculate the 
duty ratio (heat load calculated/heat load input), 
otherwise it will use the input tubeside stream 
conditions.
Fouling Resistance Allows you to specify the fouling resistance of the 
process stream.
Air Stream Conditions group
Inlet Dry Bulb Design 
Temperature
This is the temperature of the incoming air; it has 
a significant effect on the overall heat transfer 
area required. This is a useful parameter for 
helping to determine Annual Fan Power 
Consumption.
Inlet Gauge Pressure This is the gauge pressure of the air at entry to the 
bundle. This item is intended primarily for ducted 
systems where there may be a slight positive air 
inlet pressure. Negative values may also be 
used.The default air pressure is the International 
Standard Atmosphere at sea level, 1013mbar. Use 
either or both inlet gauge pressure and altitude to 
specify the actual inlet air pressure.
Inlet Humidity 
Parameter
Select the way in which the Inlet Humidity Value 
will be expressed:
• Humidity ratio (default)
• Relative humidity
The only two-phase system that ACOL can handle 
on the X-side is the condensation of water vapour 
from a humid air stream. Important note: If you 
want to use this parameter, ensure that you have 
selected Humid Air for the X-side Option
Inlet Humidity Value This is the value of the air inlet humidity in the 
way selected by the Inlet Humidity Parameter.4-29
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4-30 Air Cooler
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ThWinter Des. 
Temperature for 
Fans Only
This is the value for the X-side Stream Winter Inlet 
Temperature (or Minimum Ambient Temperature) 
and is used for calculating maximum fan power 
consumption only. Only relevant to forced draught 
exchangers. Default value is 0°C (32°F).
Altitude This is the height of the unit above sea level. You 
can use either or both inlet gauge pressure and 
altitude to specify the actual inlet air pressure.The 
default air pressure is the International Standard 
Atmosphere at sea level, 1013mbar.
Fouling Resistance Allows you to specify the fouling resistance of the 
air stream.
X-Side Option This is the fluid you wish to use on the X-side. 
Select from Dry Air (default), Humid Air, or Dry 
Gas. Dry Air is appropriate for air-cooled heat 
exchangers and other heat exchangers where air 
is being heated. Dry Gas is appropriate for waste 
heat recovery units where gases such as flue 
gases are being cooled. Also for any exchanger 
where gases other than or including air are 
handled. ACOL cannot handle condensation of any 
of the components of the gas stream. 
Air Mass Flow Rate Allows you to specify the air mass flow rate for the 
air stream. You can also edit this value on the 
Rating tab.
Solution Estimates - Optional group
For ACOL to run, it must have initial values for this group. Only the estimate 
that applies to the current calculation will be used.
Process Stream Flow 
Rate Estimate
Provides an initial value for ACOL calculations. If 
you do not enter a value, the following estimates 
are used.
When calculating the process mass flow rate:
Process Mass Flow = 5kg/s
When calculating the air mass flow rate:
No estimate required
Delta T Estimate Provides an initial value for ACOL calculations. If 
you do not enter a value, the following estimates 
are used.
When calculating the outlet process temperature:
Outlet Process temp = Inlet Process temp - 
10°C
When calculating the inlet process temperature:
Inlet Process temp = Outlet Process temp + 
10°C
Object Description4-30
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Heat Transfer Operations 4-31
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ThMaterials Page
On this page you can define the tube, header and fin materials 
and material properties. The default material for tubes and 
headers is carbon steel; the default for fins is aluminium.
Enhanced Surfaces Page
This page changes depending on which radio button you select.
• Specific Enhancements Radio Button
 Figure 4.7
 Figure 4.84-31
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4-32 Air Cooler
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ThThe following table lists and describes some of the 
objects available for the Specific Enhancements option. 
Object Description
Enhancement 
Specification
Select the type of enhancement specification from the 
drop-down list. Available options appear in the image 
to the left.
Pass Number 
Enhancement 
Starts
Enter the pass number from which (and including) the 
tube enhancement is to take effect. This allows you to 
specify tubeside enhancement where it might be most 
effective.
Pass Number 
Enhancement 
Stops
Enter the pass number at which (and including) the 
tube enhancement is to stop.
If this item is left blank and tubeside enhancement has 
been specified, then the enhancement will stop at the 
last pass.
Twisted Tape 
Thickness
This is the thickness of the twisted tape insert. Default 
value is 0.5 mm (0.02 in).
180 Degree 
Twist Pitch
This is the pitch of the twisted tape insert as it 
completes one 180-degree twist. Default value is 50 
mm (2 in).
Wet Wall 
Desuperheating
Select YES for wet wall (or NO for dry wall) 
desuperheating. Wet wall desuperheating occurs when 
the bulk temperature of a stream is above the dew 
point, but the local wall temperature is below the dew 
point. If the wet wall calculation is selected, the 
program corrects the heat transfer rate in the 
desuperheating zone to allow for condensation 
occurring at the wall. When the alternative dry wall 
calculation is selected the program uses the single 
phase gas coefficient until the bulk vapour temperature 
reaches the dew point. As a rule, dry wall coefficients 
are usually lower than wet wall coefficients, and more 
conservative. Default is Yes
Reynolds 
Number
This field allows you to enter values of Reynolds 
Number for the first and second points which 
correspond with input values of tubeside heat transfer j 
factors and friction factors. The reference diameter is 
the tube inside diameter. A log-log interpolation is 
performed between two points. Extrapolation is not 
permitted.
Heat Transfer J 
Factor
This field allows you to enter values of the heat 
transfer j factor corresponding to the values of the 
Reynolds Number for Points 1 and 2. This is particularly 
useful for specifying the performance of tube inserts. A 
log-log interpolation is performed between two points. 
Extrapolation is not permitted.
Friction Factor This field allows you to enter values of the friction 
factor corresponding to the values of the Reynolds 
Number for Points 1 and 2. This is particularly useful 
for specifying the performance of tube inserts. A log-
log interpolation is performed between two points. 
Extrapolation is not permitted.4-32
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Heat Transfer Operations 4-33
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Th• General Enhancements Radio Button
The following table lists and describes some of the 
objects available for the General Enhancements option.
 Figure 4.9
Object Description
Surface Identification group
Add Surface button Adds another surface set to the matrix.
Remove Surface button Removes a surface set from the matrix.
Enhanced Surface Name Displays the system generated set name. 
Maximum number of surfaces = 20.
Where Used Defines where the enhanced surface is used.
Surface Performance Data group
Set list Displays the list of available sets.
Reynolds Number Allows you to specify the Reynolds Number for 
the selected set. You can enter up to four 
values.
Friction Factor Allows you to specify the friction factor for the 
selected set. You can enter up to four values.
Colburn J Factor Allows you to specify the Colburn J Factor for 
the selected set. You can enter up to four 
values.4-33
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4-34 Air Cooler
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ThOptions Page
This page determines what appears on the Results page.  
 Figure 4.10
Object Description
Main Output Options group
Units of Output Determines the output data units. Choose from S.I., 
British/US, and Metric.
Physical Properties Package Determines where the output data goes: line printer, 
separate file, or no output
Detailed Table Output Determines the output table format.
Lines per Page for Line 
Printer Output
Sets the number of lines on a page for printed output.
Units of Repeat Output Sets the units for repeated output on the Results page; 
contains the same options as Units of Output.
Final Output Page Select Yes if you require the final output page in the 
lineprinter output.
Header Output Select Yes to show headers in the lineprinter output.
Temperature Table Select Yes to show the temperature table in the 
lineprinter output.
Pressure Tables Select Yes to show the pressure tables in the 
lineprinter output.
Monitor Output group
Input Data Use the default setting.
Representative Tube Details Use the default setting.4-34
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Heat Transfer Operations 4-35
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ThResults Page
This page displays the result of the ACOL calculations. Set the 
format of the Results page on the Options page.
4.1.9 HTFS+ - ACOL+ Tab
By providing access to the ACOL+ Engine, HYSYS provides a 
detailed calculation for Air Cooler heat exchangers. To access 
the ACOL+ functions on the HTFS+-ACOL+ tab, you must first 
do the following:
• Install and license ACOL+.
• Select ACOL+ Design from the Air Cooler Model drop-
down list on the Parameters page of the Design tab.
The Monitor Output group is used for debugging purposes 
only. Use the default settings.
 Figure 4.11
If you provide more data than is required, ACOL+ will 
perform consistency checks and warn you of any 
discrepancies.4-35
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4-36 Air Cooler
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ThImporting and Exporting ACOL+ 
Input Files
Import and Export buttons appear on every page of the 
HTFS+-ACOL+ tab. These buttons allow you to import existing 
ACOL+ data or export the current data. The file format used is 
ACOL+ Input files [*.edr].
HTFS+ Results
On each tab, key results are displayed. To view the full HTFS+ 
results, click the HTFS+ Results button.
Bundle Geometry Page
The Bundle Geometry page content changes depending on the 
radio button you select. The radio button options are:
• Headers
• Nozzles
• Bundle
• Tubes
Headers Radio Button
The following fields appear when you select the Headers radio 
button.
• Header Type
• U-Bend Configuration
• Header side wall clearance
• Header top wall clearance
• Header bottom wall clearance
• Depth
• Wall thickness
• Tubesheet thickness4-36
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Heat Transfer Operations 4-37
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ThNozzles Radio Button
The following fields appear when you select the Nozzles radio 
button.
• Actual ID
• Actual OD
• Quantity
• Orientation
• Length
• Flange thickness
• Flange diameter
• Nozzle flange rating
• Nozzle flange type
Bundle Radio Button
The following fields appear when you select the Bundle radio 
button.
• Number of Passes
• Number of Rows
• Number of Tubes
• Type of Bundle
• Flow Direction
• Rows per Pass
• Maximum Number of Tubes per Row per pass
• Transverse Pitch
• Longitudinal Pitch
• Tube Layout Angle
• Tube Support Number
• Tube Support Width
To specify the bundle geometry, click the Bundle Diagram 
button.4-37
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4-38 Air Cooler
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ThTubes Radio Button
The following fields appear when you select the Tubes radio 
button.
• Number of Tubes
• Tube Shape
• Effective Length
• Tube Length
• Tube Material
• Tube OD
• Tube ID
• Tube Wall Thickness
Extended Surfaces Page 
The fields on the Extended Surfaces page depend on the radio 
button you select. The radio button options are:
• Fins
• Serrations/Studs
Fins
The following fields appear when you select the Fins radio 
button.
• Fin Type
• Fin Material
• Fin Frequency
• Fin Tip Diameter
• Fin Thickness
• Fin Root Diameter
• Fin Root Thickness
• Major Axis OD
• Minor Axis OD
• Major Axis Fin OD
• Minor Axis Fin OD
• HT Area Scaler
• Last Row of Tubes4-38
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ThSerrations/Studs
The following fields appear when you select the Serrations/
Studs radio button.
• Fin Type
• Serration Width
• Serration Length
• Serration Fin Method
• Number of studs per crown
• Stud width
ACHE Geometry Page 
The fields on the ACHE Geometry page depend on the radio 
button you select. The radio button options are:
• Unit
• Accessories/Clearance
Unit
The following fields appear when you select the Unit radio 
button.
• Number of Bays per Unit
• Bundles per Bay
• Fans per Bay
• Number of Sides Fan Draws Air from
• Flow Direction
• Frame Type
• Angle of Outside Flow
• Tube Side Flow Direction
• Fan Configuration
• Fan Inlet Type
• Plenum Depth
• Ground Clearance
• Chimney Height above Bundle4-39
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4-40 Air Cooler
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ThAccessories/Clearance
The following fields appear when you select the Accessories/
Clearance radio button.
• Louvre type
• Louvre opening angle
• Louvre pressure loss coef.
• Louvre control
• Steam coil
• Width of sideframe
• Sideframe to last tube row fin
• Sideframe to 1st tube row fin
• Distance between bundles within bays
• Distance between bundles in adjacent bays
• Angle of sideframe to horizontal
• Bundle drainage angle
Process Data Page
The following fields appear on the Process Data page.
• Process Streams group
- Total Mass Flow
- Inlet Mass Quality
- Outlet Mass Quality
- Inlet Temperature
- Outlet Temperature
- Inlet Pressure
- Heat Load
- Fouling Resistance
• Air Stream Conditions group
- Inlet Temperature
- Outlet Temperature
- Minimum Ambient Temperature
- Altitude
- Inlet Group Pressure
- Allowable Pressure Drop
- Fouling
- Humidity Option
- Humidity Ratio
- Relative Humidity4-40
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ThMaterials Page
The following fields appear on the Materials page.
• Tube Material
• Header Material
• Tubesheet Material
• Tube Thermal Conductivity
• Tube Density
• Header Density
• Fin Material
• Fin Thermal Conductivity
• Fin Material Density
Enhanced Surfaces Page
The fields on this page depend on which radio button you select: 
• Tube Side
• Outside
Tube Side
The following fields appear when you select the Tube Side radio 
button.
• Enhancement Type
• Start Pass
• End Pass
• HTC Factor 
• Friction Factor
• Twisted Tape Thickness
• Twisted Tape Pitch
• Reynolds Number
• Colburn Factor
• Friction Factor
• Reynolds 1
• HT j Factor 1
• Friction Factor 1
• Reynolds 2
• HT j Factor 2
• Friction Factor 2 4-41
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4-42 Air Cooler
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ThOutside
The following fields appear when you select the Outside radio 
button.
• Enhancement Type
• Perf. DB Used
• Pt. 1 Flow Parameter
• Pt. 1 Ho Parameter
• Pt. 1 DP Parameter
• Pt. 2 Flow Parameter
• Pt. 2 Ho Parameter
• Pt. 2 DP Parameter
• Ho Curve Coeff.
• Ho Curve Exp.
• DP Curve Coeff.
• DP Curve Exp.
• Ho Scaling Factor
Options Page
The following fields appear on the Options page.
• Outside Vapor HTC
• Tubeside Vapor HTC
• Tubeside 2 phases HTC
• Tubeside liquid HTC
• Calculation steps
• Number of iterations
• Detailed calculation accuracy %
• Main iteration accuracy %
• Wet wall desuperheating option
• Tube side flow distribution
• Velocity heads
• Highfin tube calculation
• Low Fin Method
• Outside Radiation HT
• Exit pressure recovery coef.
• Fan guard pressure loss coef.
• Fan guard support pressure loss coef.4-42
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ThStructures Page
The following fields appear on the Structure page.
• Bays share support legs
• Number of support legs
• Leg width in the X dir.
• Leg width in the Z dir.
• Ratio fan height to fan diameter
• Tubesheet to sup. leg clearances
• Sideframe to sup. leg clearance
• Walkway thickness
• Header walkway width
• Header floor to bottom distance
• Header offset from the headers
• Bay walkway width
• Bay offset from expected position
• Fan walkway width
• Fan offset from fan centerlines
• Fan length beyond centers
• Walkway railing height
• Walkway railing post spacing
• Walkway distance below fan rings
Fans Page
The fields on the Fans page depend on which radio button you 
select. The radio button options are:
• Fans/Plenum
• Motor
Fans/Plenum
The following fields appear when you select the Fans/Plenum 
radio button.
• Fan Configuration
• Fan Inlet Type
• Fan Drive Type
• Fan Pit Control
• Fan Speed4-43
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4-44 Air Cooler
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Th• Fan Drive Efficiency
• Fan Static Efficiency
• Plenum Type
• Plenum Wall to Fan Diameter Ratio
• Plenum Depth to Fan Diameter Ratio
• Fan Ring Length to Fan Diameter Ratio
• Position of Fan Ring to Length Ratio
• Plenum to Bundle Frame X Clearance
• Plenum to Tubesheet Z Clearance
• Fan Entry Lip Width
• Fan Center offset
Motor
The following fields appear when you select the Motor radio 
button.
• Vertical distance from fan motor to fan center
• Radial distance from fan motor shaft end to fan center
• Fan Motor Body Length
• Fan Motor Body Diameter
• Fan Motor Shaft Length
• Fan Motor Shaft Diameter
• Length of motor section nearest shaft/motor length
• Diameter of motor section nearest shaft/motor diameter
• Corner radius of near motor section/motor length
• Length of far motor section/motor length
• Diameter of far motor section/motor diameter
• Angle in XZ plane of all but last fan motor
• Angle in XZ plane of the last fan motor4-44
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Heat Transfer Operations 4-45
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Th4.2 Cooler/Heater
The Cooler and Heater operations are one-sided heat 
exchangers. The inlet stream is cooled (or heated) to the 
required outlet conditions, and the energy stream absorbs (or 
provides) the enthalpy difference between the two streams. 
These operations are useful when you are interested only in how 
much energy is required to cool or heat a process stream with a 
utility, but you are not interested in the conditions of the utility 
itself.
4.2.1 Theory
Steady State
The primary difference between a cooler and a heater is the sign 
convention. You specify the absolute energy flow of the utility 
stream, and HYSYS then applies that value as follows:
• For a Cooler, the enthalpy or heat flow of the energy 
stream is subtracted from that of the inlet stream:
• For a Heater, the heat flow of the energy stream is 
added:
The difference between the Cooler and Heater is the energy 
balance sign convention.
The Cooler and Heater use the same basic equation.
Heat Flowinlet - Dutycooler = Heat Flowoutlet (4.12)
Heat Flowinlet + Dutycooler = Heat Flowoutlet (4.13)4-45
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4-46 Cooler/Heater
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ThDynamic
The Cooler duty is subtracted from the process holdup while the 
Heater duty is added to the process holdup. 
For a Cooler, the enthalpy or heat flow of the energy stream is 
removed from the Cooler process side holdup: 
For a Heater, the enthalpy or heat flow of the energy stream is 
added to the Heater process side holdup: 
where:  
M = process fluid flow rate
 = density
H = enthalpy
Qcooler = cooler duty
Qheater = heater duty
V = volume shell or tube holdup
Pressure Drop
The pressure drop of the Cooler/Heater can be determined in 
one of two ways:
• Specify the pressure drop manually.
• Define a pressure flow relation in the Cooler or Heater by 
specifying a k-value.
If the pressure flow option is chosen for pressure drop 
determination in the Cooler or Heater, a k value is used to relate 
the frictional pressure loss and flow through the Cooler/Heater. 
(4.14)
(4.15)
M Hin Hout–( ) Qcooler– ρ
d VHout( )
dt
----------------------=
M Hin Hout–( ) Qheater+ ρ
d VHout( )
dt
----------------------=
ρ
4-46
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Heat Transfer Operations 4-47
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ThThe relation is similar to the general valve equation:
This general flow equation uses the pressure drop across the 
heat exchanger without any static head contributions. The 
quantity, P1 - P2, is defined as the frictional pressure loss which 
is used to “size” the Cooler or Heater with a k-value.
Dynamic Specifications
In general, two specifications are required by HYSYS in order for 
the Cooler/Heater unit operation to fully solve in Dynamic mode:
4.2.2 Heater or Cooler Propety 
View
There are two ways that you can add a Heater or Cooler to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Heat Transfer Equipment radio button.
(4.16)
Dynamic 
Specifications
Description
Duty Calculation The duty applied to the Cooler/Heater can be 
calculated using one of three different models:
• Supplied Duty
• Product Temp Spec
• Duty Fluid
Specify the duty model in the Model Details group on 
the Specs page of the Dynamics tab.
Pressure Drop Either specify an Overall Delta P or an Overall K-value.
Specify the Pressure Drop calculation in the Dynamic 
Specifications group on the Specs page of the 
Dynamics tab.
flow density k× P1 P2–=4-47
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4-48 Cooler/Heater
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Th3. From the list of available unit operations, select Cooler or 
Heater.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Cooler icon or the Heater icon. 
The Cooler or Heater property view appears.
4.2.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 4.12
Cooler icon
Heater icon4-48
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ThConnections Page
The Connections page is used to define all of the connections to 
the Cooler/Heater. You can specify the inlet, outlet, and energy 
streams attached to the operation on this page. The name of the 
operation can be changed in the Name field.
Parameters Page
The applicable parameters are the pressure drop (Delta P) 
across the process side, and the duty of the energy stream. 
Both the pressure drop and energy flow can be specified directly 
or can be determined from the attached streams. 
 Figure 4.13
 Figure 4.144-49
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4-50 Cooler/Heater
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ThYou can specify a negative duty value, however, be aware of the 
following:
• For a Cooler, a negative duty means that the unit is 
heating the inlet stream.
• For a Heater, a negative duty means that the unit is 
cooling the inlet stream.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor that allows you to record 
any comments or information regarding the specific unit 
operation, or the simulation case in general.
4.2.4 Rating Tab
You must specify the rating information only when working with 
a dynamics simulation.
Nozzles Page
On the Nozzles page, you can specify nozzle parameters on both 
the inlet and outlet streams connected to a Cooler or Heater. 
The addition of nozzles to Coolers and Heaters is relevant when 
creating dynamic simulations.
HYSYS uses the proper sign convention for the unit you have 
chosen, so you can enter a positive duty value for both 
heater and cooler.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.4-50
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ThHeat Loss Page
Rating information regarding heat loss is relevant only in 
Dynamic mode. The Heat Loss page contains heat loss 
parameters that characterize the amount of heat lost across the 
vessel wall.
In the Heat Loss Model group, you can choose either a Simple or 
Detailed heat loss model or no heat loss through the vessel 
walls.
Simple Model
The Simple model allows you to either specify the heat loss 
directly, or have the heat loss calculated from the specified 
values:
• Overall U value
• Ambient Temperature
The heat transfer area, A, and the fluid temperature, Tf, are 
calculated by HYSYS using the following equation:
For a Cooler, the parameters available for the Simple model 
appear in the figure below.
Q = UA(Tf - Tamb) (4.17)
 Figure 4.154-51
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4-52 Cooler/Heater
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ThThe simple heat loss parameters are as follows:
• Overall Heat Transfer Coefficient
• Ambient Temperature
• Overall Heat Transfer Area
• Heat Flow
The heat flow is calculated as follows:
where:  
U = overall heat transfer coefficient
A = heat transfer area
TAmb = ambient temperature
T = holdup temperature
Heat flow is defined as the heat flowing into the vessel. The heat 
transfer area is calculated from the vessel geometry. The 
ambient temperature, TAmb, and overall heat transfer coefficient, 
U, can be modified from their default values shown in red.
Detailed Model
The Detailed model allows you to specify more detailed heat 
transfer parameters. 
4.2.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the unit operation. 
Heat Flow = UA(TAmb - T) (4.18)
The HYSYS Dynamics license is required to use the Detailed 
Heat Loss model.
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.6.1 - 
Detailed Heat Model in 
the HYSYS Dynamic 
Modeling guide for more 
information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.4-52
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Th4.2.6 Performance Tab
The Performance tab contains pages that display calculated 
stream information. By default, the performance parameters 
include the following stream properties:
• Pressure
• Temperature
• Vapour Fraction
• Enthalpy
Other stream properties can be viewed by adding them to the 
Viewing Variables group on the Setup page. 
All information appearing on the Performance tab is read-only. 
The Performance tab contains the following pages:
• Profiles
• Plots
• Tables
• Setup
Profiles Page
In Steady State mode, HYSYS calculates the zone conditions for 
the inlet zone only, regardless of the number of zones specified. 
 Figure 4.164-53
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4-54 Cooler/Heater
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ThPlots Page
On the Plots page, you can graph any of the default 
performance parameters to view changes that occur across the 
operation.
All default performance parameters are listed in the X Variable 
and Y Variable drop-down lists below the graph. Select the axis 
and variables you want to compare, and the plot is displayed.
To graph other variables, you need to go to the Setup page and 
add them to the Selected Viewing Variables group from the 
Available Variables listed.
A temperature - pressure graph for a Cooler, with 5 specified 
intervals is displayed in the figure below.
In Steady State mode, stream property readings are taken 
only from the inlet and outlet streams for the plots. As such, 
the resulting graph is always a straight line. The property 
values are not calculated incrementally through the 
operation.
You can right-click on the graph area to access the graph 
controls and manipulate the graph appearance.
 Figure 4.17
Refer to Section 1.3.1 - 
Graph Control Property 
View for more 
information.
You can specify the number 
of calculation intervals you 
want calculated across the 
graph in the Interval field. 
This divides the plot line into 
equally spaced intervals with 
the values displayed as 
described on the Tables 
page.4-54
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Heat Transfer Operations 4-55
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ThTables Page
The Tables page displays the results of the Cooler/Heater in a 
tabular format. All default values for the pressure, temperature, 
vapour fraction, and enthalpy calculated for each interval are 
listed here.  
 Figure 4.18
Information on the Tables page is read-only, except the 
Intervals value.
You can specify the 
number of calculation 
intervals you want 
calculated across the data 
in the Interval field. This 
divides the data up into 
equally spaced intervals.
You can select what phase 
options to view by clicking 
on the checkbox. For some 
options you need to add 
variables via the Setup 
page.4-55
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4-56 Cooler/Heater
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ThSetup Page
The Setup page allows you to filter and add variables to be 
viewed on the Plots and Tables pages.
The variables that are listed in the Selected Viewing Variables 
group are available in the X and Y drop down list for plotting on 
the Plots page. The variables are also available for tabular plot 
results on the Tables page based on the Phase Viewing Options 
selected.
4.2.7 Dynamics Tab
In the Dynamic mode, the values you enter in the Dynamics tab 
affects the calculation. The Dynamics tab contains the following 
pages:
• Specs
• Duty Fluid
• Holdup
• Stripchart
 Figure 4.19
If you are working exclusively in Steady State mode, you do 
not need to change any of the values on the pages accessible 
on the Dynamics tab.4-56
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ThSpecs Page
The Specs page contains information regarding the calculation 
of pressure drop across the Cooler or Heater:
Zone Information
HYSYS has the ability to partition heat transfer opera6tions into 
discrete sections called zones. By dividing the unit operation into 
zones, you can make different heat transfer specifications for 
individual zones, and therefore more accurately model the 
physical process. 
Specifying the Cooler/Heater with one zone provides optimal 
speed conditions, and is usually sufficient in modeling accurate 
exit stream conditions.
Model Details
The Model Details group must be completed before the 
simulation case solves. The number of zones and the volume of 
a Cooler/Heater can be specified in this group. 
 Figure 4.204-57
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4-58 Cooler/Heater
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ThHYSYS can calculate the duty applied to the holdup fluid using 
one of the three different methods described in the table below.
Dynamic Specifications
The Dynamic Specifications group allows you to specify how the 
pressure drop is calculated across the Cooler or Heater unit 
operation. The table below describes the specifications. 
Model Description
Supplied 
Duty
If you select the Supplied Duty radio button, you must 
specify the duty applied to the Cooler/Heater. It is 
recommended that the duty supplied to the unit operation 
be calculated from a PID Controller or a Spreadsheet 
operation that can account for zero flow conditions.
Product 
Temp Spec
If you select the Product Temp Spec radio button, you must 
specify the desired exit temperature. HYSYS back 
calculates the required duty to achieve the specified desired 
temperature. This method does not run as fast as the 
Supplied Duty model.
Duty Fluid If you select the Duty Fluid radio button, you can model a 
simple utility fluid to heat or cool your process stream. The 
following parameters must be specified for the utility fluid 
on the Duty Fluid page of the Dynamics tab:
• Mass Flow
• Holdup Mass
• Mass Cp
• Inlet temperature 
• Average UA
Specification Description
Overall Delta 
P
A set pressure drop is assumed across the Cooler or Heater operation with 
this specification. The flow and the pressure of either the inlet or exit stream 
must be specified, or calculated from other unit operations in the flowsheet. 
The flow through the valve is not dependent on the pressure drop across the 
Cooler or Heater. To use the overall delta P as a dynamic specification, select 
the corresponding checkbox in the Dynamic Specifications group
Overall k 
Value
The k-value defines the relationship between the flow through Cooler or 
Heater and the pressure of the surrounding streams. You can either specify 
the k-value, or have it calculated from the stream conditions surrounding the 
unit operation. You can “size” the Cooler or Heater with a k-value by clicking 
the Calculate k button. Ensure that there is a non zero pressure drop across 
the Cooler or Heater before the Calculate k button is clicked. To use the k-
value as a dynamic specification, select the corresponding checkbox in the 
Dynamic Specifications group.4-58
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ThZone Dynamic Specifications
If the Cooler or Heater operation is specified with multiple 
zones, you can click the Spec Zones button to define dynamic 
specifications for each zone.
In the Delta P Specs and Duties group, you can specify the 
following parameters:
The Cooler or Heater unit operation, like other dynamic unit 
operations, should use the k-value specification option as 
much as possible to simulate actual pressure flow relations 
in the plant.
 Figure 4.21
Dynamic 
Specification
Description
dP Value Allows you to specify the fixed pressure drop value.
dP Option Allows you to either specify or calculate the pressure drop 
across the Cooler or Heater. Specify the dP Option with one 
of the following options:
• user specified. The pressure drop across the zone is 
specified by you in the dP Value field.
• non specified. Pressure drop across the zone is 
calculated from a pressure flow relationship. You must 
specify a k-value, and activate the specification for the 
zone in the Zone Conductance Specifications group.
Duty A fixed duty can be specified across each zone in the Cooler 
or Heater unit operation.4-59
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4-60 Cooler/Heater
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ThIn the Zone Conductance Specifications group, you can specify 
the following parameters:
Duty Fluid Page
The Duty Fluid page becomes visible if the Duty Fluid radio 
button is selected on the Specs page.
The Duty Fluid page allows you to enter the following 
parameters to define your duty fluid:
• Mass Flow
• Holdup mass
• Mass Cp
• Inlet Temperature
• Average UA
The Counter Flow checkbox allows you to specify the direction of 
flow for the duty fluid. When the checkbox is active, you are 
using a counter flow.
Dynamic 
Specification
Description
k The k-value for individual zones can be specified in this 
field. You can either specify the k-value, or have it 
calculated by clicking the Calculate k button
Specification Activate the specification if the k-value is to be used to 
calculate pressure across the zone.
 Figure 4.224-60
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ThThe View Zones button displays the duty fluid parameters for 
each of the zones specified on the Specs page.
Holdup Page
The Holdup page contains information regarding the Cooler or 
Heater holdup properties, composition, and amount.
The Individual Zone Holdups group contains detailed holdup 
properties for each holdup in the Cooler or Heater. In order to 
view the advanced properties for individual holdups, you must 
first choose the individual zone in the Zone drop-down list.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
 Figure 4.23
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.4-61
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4-62 Fired Heater (Furnace)
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Th4.3 Fired Heater (Furnace)
The dynamic Fired Heater (Furnace) operation performs energy 
and material balances to model a direct Fired Heater type 
furnace. This type of equipment requires a large amount of heat 
input. Heat is generated by the combustion of fuel and 
transferred to process streams. A simplified schematic of a 
direct Fired Heater is illustrated in the figure below. 
In general, a Fired Heater can be divided into three zones:
• Radiant zone
• Convective zone
• Economizer zone
 Figure 4.24
The Fired Heater operation is available as a dynamic unit 
operation only.4-62
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ThThe Fired Heater operation allows multiple stream connections 
at tube side in each zone and optional economizer, and 
convection zone selections. The operation incorporates a single 
burner model, and a single feed inlet and outlet on the flue gas 
side.
The following are some of the major features of the dynamic 
Fired Heater operation:
• Flexible connection of process fluid associated in each 
Fired Heater zone. For example, radiant zone, convective 
zone, or economizer zone. Different Fired Heater 
configurations can be modeled or customized using tee, 
mixer, and heat exchanger unit operations.
• A pressure-flow specification option on each side and 
pass realistically models flow through Fired Heater 
operation according to the pressure gradient in the entire 
pressure network of the plant. Possible flow reversal 
situations can therefore be modeled.
• A comprehensive heat calculation inclusive of radiant, 
convective, and conduction heat transfer on radiant zone 
enables the prediction of process fluid temperature, Fired 
Heater wall temperature, and flue gas temperature.
• A dynamic model which accounts for energy and material 
holdups in each zone. Heat transfer in each zone 
depends on the flue gas properties, tube and Fired 
Heater wall properties, surface properties of metal, heat 
loss to the ambient, and the process stream physical 
properties.
• A combustion model which accounts for imperfect mixing 
of fuel, and allows automatic flame ignition or 
extinguished based on the oxygen availability in the fuel 
air mixture. 
To define the number of zones required by the Fired Heater, 
enter the number in #External Passes field on Connections 
page of the Design tab.4-63
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4-64 Fired Heater (Furnace)
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Th4.3.1 Theory
Combustion Reaction
The combustion reaction in the burner model of the Fired Heater 
performs pure hydrocarbon (CxHy) combustion calculations only. 
The extent of the combustion depends on the availability of 
oxygen which is usually governed by the air to fuel ratio.
Air to fuel ratio (AF) is defined as follows:
You can set the combustion boundaries, such as the maximum 
AF and the minimum AF, to control the burner flame. The flame 
cannot light if the calculated air to fuel ratio falls below the 
specified minimum air to fuel ratio. The minimum air to fuel ratio 
and the maximum air to fuel ratio can be found on the 
Parameters page of the Design tab.
The heat released by the combustion process is the product of 
molar flowrate, and the heat of formation of the products minus 
the heat of formation of the reactants at combustion 
temperature and pressure. In the Fired Heater unit operation, a 
traditional reaction set for the combustion reactions is not 
required. You can choose the fuels components (the 
hydrocarbons and hydrogen) to be considered in the combustion 
reaction. You can see the mixing efficiency of each fuel 
component on the Parameter page of the Design tab.
(4.19)
AF
Mass of flow O2
Σ Mass flow of fuel
---------------------------------------------------⎝ ⎠
⎛ ⎞
Mass Ratio of O2 in Air
---------------------------------------------------------------=4-64
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ThHeat Transfer
The Fired Heater heat transfer calculations are based on energy 
balances for each zone. The shell side of the Fired Heater 
contains five holdups:
• three in the radiant zone
• a convective zone
• an economizer zone holdup as outlined previously in 
Figure 4.24. 
For the tube side, each individual stream passing through the 
respective zones is considered as a single holdup.
Major heat terms underlying the Fired Heater model are 
illustrated in the figure below.
 Figure 4.254-65
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4-66 Fired Heater (Furnace)
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ThThe heat terms related to the tubeside are illustrated in the 
figure below.
Taking Radiant zone as an envelope, the following energy 
balance equation applies:
where:  
 = energy accumulation in radiant zone holdup 
shell side
 Figure 4.26
(4.20)
d MradHrad( )
dt
--------------------------------
d MRPFTubeHRPFTube( )
dt
---------------------------------------------------------+
MRPFHRPF( )IN MRPFHRPF( )OUT– MFGHFG( )IN
MFGHFG( )OUT– QRadToCTube– Qrad wall  sur– Qcon  wall sur–
Qrad  wall  to  tube Qcon  to  wall– Qreaction
+
+ +
=
d MradHrad( )
dt
--------------------------------4-66
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Th = energy accumulation in radiant zone 
process fluid holdup (tube side)
(MRPFHRPF)IN = total heat flow of process fluid entering 
radiant zone tube
(MRPFHRPF)OUT = total heat flow of process fluid exiting 
radiant zone tube
(MFGHFG)IN = total heat flow of fuel gas entering radiant zone
(MFGHFG)OUT = total heat flow of fuel gas exiting radiant zone
QRadToCTube = radiant heat of radiant zone to convective 
zone’s tube bank
Qrad_wall_sur = radiant heat loss of Fired Heater wall in radiant 
zone to surrounding
Qcon_wall_sur = convective heat loss of Fired Heater wall in 
radiant zone to surrounding
Qrad_wall_to_tube = radiant heat from inner Fired Heater wall to 
radiant zone’s tube bank
Qrad_flame_wall = radiant heat from flue gas flame to inner 
Fired Heater wall
Qcon_to_wall = convective heat from flue gas to Fired Heater 
inner wall
Qreaction = heat of combustion of the flue gas
Radiant Heat Transfer
For a hot object in a large room, the radiant energy emitted is 
given as:
where:  
 = Stefan-Boltzmann constant, 5.669x10-8 W/m2K4
 = emissivity, (0-1), dimensionless
A = area exposed to radiant heat transfer, m2
(4.21)
d MRPFTubeHRPFTube( )
dt
---------------------------------------------------------
Qradiative δAε T1
4 T2
4–( )=
δ
ε
4-67
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4-68 Fired Heater (Furnace)
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ThT1 = temperature of hot surface 1, K
T2 = temperature of hot surface 2, K
Convective Heat Transfer
The convective heat transfer taking part between a fluid and a 
metal is given in the following:
where:  
U = overall heat transfer coefficient, W/m2K
A = area exposed to convective heat transfer, m2
T1 = temperature of hot surface 1,K
T2 = temperature of surface 2, K
The U actually varies with flow according to the following flow-U 
relationship if this Flow Scaled method is used:
where:  
Uspecified = U value at steady state design conditions.
The ratio of mass flow at time t to reference mass flow is also 
known as flow scaled factor. The minimum flow scaled factor is 
the lowest value, which the ratio is anticipated at low flow 
region. For the Fired Heater operation, the minimum flow scaled 
factor can be expressed only as a positive value.
(4.22)
(4.23)
Qconvective UA T1 T2–( )=
Uused Uspecified
Mass flow at time t
Reference Mass flow
-------------------------------------------------------⎝ ⎠
⎛ ⎞ 0.8
=
4-68
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ThFor example, if the minimum flow scaled factor is +0.001 
(0.1%), when this mass flow ratio is achieved, the Uused stays 
as a constant value. Therefore,
Conductive Heat Transfer
Conductive heat transfer in a solid surface is given as:
where:  
k = thermal conductivity of the solid material, W/mK
 = thickness of the solid material, m
A = area exposed to conductive heat transfer, m2
T1 = temperature of inner solid surface 1, K
T2 = temperature of outer solid surface 2, K
Pressure Drop
The pressure drop across any pass in the Fired Heater unit 
operation can be determined in one of two ways:
• Specify the pressure drop - delta P.
• Define a pressure flow relation for each pass by 
specifying a k-value
If the pressure flow option is chosen for pressure drop 
determination in the Fired Heater pass, a k value is used to 
relate the frictional pressure drop and molar flow, F through the 
Fired Heater. This relation is similar to the general valve 
equation:
(4.24)
(4.25)
(4.26)
Uused Uspecified 0.001( )0.8=
Qconductive kA–
T1 T2–( )
Δt
---------------------=
Δt
F k ρ P1 P2–( )=4-69
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4-70 Fired Heater (Furnace)
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ThThis general flow equation uses the pressure drop across the 
Fired Heater pass without any static head contribution. The 
quantity, (P1-P2) is defined as the frictional pressure loss which 
is used to “size” the flow.
The k value is calculated based on two criteria:
• If the flow of the system is larger than the value at kref (k 
reference flow), the k value remain unchanged. It is 
recommended that the k reference flow is taken as 40% 
of steady state design flow for better pressure flow 
stability at low flow range.
• If the flow of the system is smaller than the kref, the k 
value is given by:
where:  
Factor = value is determined by HYSYS internally to take into 
consideration the flow and pressure drop relationship 
for low flow regions.
The effect of kref is to increase the stability by modeling a more 
linear relationship between flow and pressure. This is also more 
realistic at low flows.
Dynamic Specifications
The following is a list of the minimum specifications required for 
the Fired Heater operation to solve:
(4.27)
Dynamic 
Specifications
Description
Connections At least one radiant zone inlet stream and the 
respective outlet zone, one burner fuel/air feed stream 
and one combustion product stream must be defined. 
There is a minimum of one inlet stream and one outlet 
stream required per zone. Complete the connections 
group for each zone of the Design tab.
(Zone) Sizing The dimensions of the tube and shell in each zone in 
the Fired Heater must be specified. All information in 
the Sizing page of the Rating tab must be completed.
kused kuser  specified Factor×=4-70
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Th4.3.2 Fired Heater Property 
View
There are two ways that you can add a Fired Heater to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Heat Transfer Equipment radio button.
3. From the list of available unit operations, select Fired Heater.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Fired Heater icon.
Heat Transfer For each zone, almost all parameters in the Radiant 
Zone Properties group and Radiant/Convective/
Economizer Tube Properties groups are required except 
the Inner/Outer Scaled HX Coefficient.
Nozzle Nozzle elevation is defaulted to 0. Elevation input is 
required when static head contribution option in 
Integrator property view is selected.
Pressure Drop Either specify an overall delta P or an overall K value 
for the Fired Heater. Specify the pressure drop 
calculation method on the Tube Side PF page and Flue 
Gas PF page of the Dynamics tab.
Dynamic 
Specifications
Description
Fired Heater icon4-71
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4-72 Fired Heater (Furnace)
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ThThe Fired Heater property view appears.
4.3.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 4.274-72
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ThConnections Page
On the Connections page, you can specify the name of the 
operation, and inlet and outlet streams.
 Figure 4.28
Object Description
Econ Zone Inlet/
Outlet
You can specify multiple inlet and outlet streams 
for the Economizer zone.
Conv Zone Inlet/
Outlet
You can specify multiple inlet and outlet streams 
for the Convective zone.
Radiant Zone Inlet/
Outlet
You can specify multiple inlet and outlet streams 
for the Radiant zone.
Burner Fuel/Air Feed Specifies the stream to be used for the burner 
fuel.
Combustion Product The stream that contains the products from the 
combustion.
# External Passes You can define the number of zones required by 
the Fired Heater4-73
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4-74 Fired Heater (Furnace)
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ThParameters Page
The Parameters page is used to specify the Fired Heater 
combustion options.
This page is divided into four groups. The Flame Status group, 
along with displaying the flame status, allows you to toggle 
between a lit flame and an extinguished flame. The Oxygen 
group simply allows you to specify the oxygen mixing efficiency. 
The Combustion Boundaries group is used to set the combustion 
boundary based on a range of air fuel ratios. The checkbox, 
when active, allows you to auto-light the flame if your calculated 
air fuel ratio is within the boundary. Finally the Fuels group 
allows you to select the components present in your fuel as well 
as set their mixing efficiencies.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
 Figure 4.29
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.4-74
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ThNotes Page
The Notes page provides a text editor that allows you to record 
any comments or information regarding the specific unit 
operation, or the simulation case in general.
4.3.4 Rating Tab
The Rating tab contains the following pages:
• Sizing
• Nozzles
• Heat Transfer
Each page is discussed in the following sections.
Sizing Page
On the Sizing page, you can specify the geometry of the radiant, 
convective, and economizer zones in the Fired Heater.
 Figure 4.30
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.4-75
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4-76 Fired Heater (Furnace)
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ThFrom the Zone group on the Sizing page, you can choose 
between Radiative, Convective, and Economizer zone property 
views by selecting the appropriate radio button. These property 
views contain information regarding the tube and shell 
properties. To edit or enter parameters within these property 
views, click the individual cell and make the necessary changes.
The figure below shows an example of the Fired Heater setup 
with one radiant zone/firebox only with four tube passes. This is 
the simplest type.
 Figure 4.314-76
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Heat Transfer Operations 4-77
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ThThe figure below shows an example of the Fired Heater setup 
with a radiant, convective and economizer section.
Tube Properties Group
The Tube Properties group displays the following information 
regarding the dimension of the tube:
• stream pass
• tube inner diameter, Din
• tube outer diameter, Dout
• tube thickness
• # tubes per external pass
• tube length, L
• tube inner area
• tube outer area
• tube inner volume
A pass in the Fired Heater is defined as a path where the 
process fluid flows through a distinctive inlet nozzle and outlet 
nozzle. 
 Figure 4.324-77
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4-78 Fired Heater (Furnace)
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ThThe figure below illustrates the various dimensions of the tube 
and shell.
Shell Properties Group
The Shell Properties group displays the following information 
regarding the dimension of the shell:
• shell inner diameter, Dsin
• shell outer diameter, Dsout
• wall thickness, ts
• zone height, H
• shell inner area
• shell outer area
• shell net volume
 Figure 4.334-78
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Th• shell total volume
Nozzles Page
The information provided in the Nozzles page is applicable only 
in Dynamic mode. You can define the base elevation to ground 
level of the Fired Heater in the Nozzles page.
Heat Transfer Page
The information provided in the Heat Loss page is applicable 
only in Dynamic mode. This page displays the radiant heat 
transfer properties, heat transfer coefficients of the Fired Heater 
wall and tube, and shell area, tube area, and volume in each 
individual zone.
HYSYS accounts for the convective, conduction, and radiative 
heat transfer in the radiant zone. For the convective heat 
transfer calculation, you have two options:
• User Specified. You can specify the heat transfer 
coefficient of the inner tube and the outer tube.
 Figure 4.34
 Figure 4.354-79
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4-80 Fired Heater (Furnace)
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Th• Flow Scaled. The heat transfer coefficient is scaled 
based on a specified flow.
The scaled heat transfer coefficient is defined by Equation 
(4.23).
The same equation applies to the outer tube heat transfer 
coefficient calculation. Currently, the heat transfer coefficient U 
must be specified by the user. HYSYS calculates the heat 
transfer coefficient from the geometry/configuration of the Fired 
Heater. The radiant box or the fire box is assumed cylindrical in 
geometry.
Radiant Zone Properties Group
The following table describes each the parameters listed in the 
Radiant Zone group.
The Radiant, Convective, and Economizer Tube Properties 
groups all contain similar parameters, which are described in the 
following table.
Radiant Zone Parameter Description
Zone to Wall Emissivity Emissivity of flue gas. HYSYS uses a 
constant value.
Zone to Wall U Convective heat transfer coefficient of the 
radiative zone to the Fired Heater inner 
wall.
Outer Wall to Surrounding 
Emissivity
Emissivity of the Fired Heater outer wall.
Outer Wall to Surroundings U Convective heat transfer coefficient of the 
Fired Heater outer wall to ambient.
Furnace Wall Conductivity/
Specific Heat/Wall Density
These are user specified properties of a 
single layer of Fired Heater wall.
Tube Properties Description
Zone to Tube 
Emissivity
Emissivity of flue gas at radiant/convective zone to the 
tube in radiant/convective zone respectively.
Wall to Tube 
Emissivity
Radiant zone Fired Heater wall emissivity to the radiant 
zone tubes.4-80
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Heat Transfer Operations 4-81
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ThIn general the Tube to Fluid HX Coefficient is always shown in a 
common Fired Heater flowsheet, however, the Zone to Wall U 
and Outer Wall to Surroundings U are usually unknown. The 
Outer wall to Surroundings U can be easily estimated from the 
Fired Heater convective heat loss calculation, Equation (4.22) 
if the total heat loss via Fired Heater wall is known. The total 
heat loss is normally expressed as a percentage of total Fired 
Heater duty. A 3-5% heat loss is an acceptable estimate.
Inner HX Coeff 
Method
There are two options to calculate the Heat transfer 
coefficient in the tube: User Specified or Flow Scaled.
Flow Scaled provides a more realistic HX calculation 
where:
Tube to Fluid HX 
Coefficient
Heat transfer coefficient of the tube to the process 
fluid.
Tube to Fluid HX 
Reference Flow
Mass flow at which the tube to fluid HX coefficient is 
based on. Usually the ideal steady state flow is 
recommended as input.
Tube to Fluid HX 
Minimum Scale 
Factor
The ratio of mass flow of the process fluid to the 
reference mass flow in the tube. The valve ranges from 
a value of zero to one. If the process flow in the tube 
becomes less than the scale factor, the heat transfer 
coefficient used is smaller than U specified.
Inner Scaled HX 
Coefficient
The HX coefficient obtained if the Flow Scaled (Uused) 
method is applied to perform the calculation. 
Tube Cp, Density, 
Conductivity
Metal properties of the tube in their respective zones.
Outer HX 
Coefficient 
Method
Method used to calculate the shell side HX coefficient. 
Two options available: User Specified or Flow Scaled.
Zone to Tube HX 
Coefficient
HX coefficient in the radiative/convective/ economizer 
or flue gas zones to the respective tubes.
Zone to Tube HX 
Reference Flow
Mass flow of the flue gas at which the outer HX 
coefficient is based upon. This is usually designed 
using the ideal steady state flow of the flue gas.
Zone to Tube HX 
Minimum Scale 
Factor
Mass ratio of flue gas flow to the flue gas reference 
mass flow. This value ranges from zero to one.
If the process flow in the tubes is less than this value, 
the HX coefficient used is set to zero.
Outer Scaled U The actual HX coefficient used in the calculation if the 
Flow Scaled option is selected. 
Tube Properties Description
Uused Uspecified
mass
massref
------------------⎝ ⎠
⎛ ⎞ 0.8
=
4-81
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4-82 Fired Heater (Furnace)
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ThEstimating Zone to Wall U requires trial and error techniques. 
Enter a value of U then observe the temperature profile of the 
flue gas exiting the radiant zone.
4.3.5  Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the heat exchanger unit operation. 
To view the stream parameters broken down per stream phase, 
open the Worksheet tab of the stream property view.
4.3.6 Performance Tab
The performance tab contains three pages which highlight the 
calculated temperature, duty, and pressure of the Fired Heater 
operation.
The PF Specs page is relevant to dynamics cases only.
 Figure 4.36
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.4-82
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ThDuty Page
The Duty page displays the results of the Fired Heater energy 
balance calculation. The Duty page contains three levels/
branches: Radiant Zone, Convective Zone, and Economizer 
Zone.
• If you select Radiant Zone from the tree browser, the 
following four levels/branches containing information 
regarding the Tube Duty results and Zone Duty results 
appear:
- Overall
- Holdup
 Figure 4.37
 Figure 4.384-83
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4-84 Fired Heater (Furnace)
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Th- Tubes
- Wall
 Figure 4.39
 Figure 4.404-84
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Th• If you select the Convective Zone from the tree 
browser, the following parameters from the Tube Duty 
Results group and the Zone Duty Results group appear:
• If you select the Economizer Zone from the tree 
browser, the following parameters from the Tube Duty 
results group and Zone Duty results group appear:
Process Fluid Page
The Process Fluid page contains two sub-pages:
• Temperatures
• Pressures
In the Temperatures sub-page, the following parameters 
appear:
• Inlet Temp, Inlet stream process fluid temperature
• Outlet Temp, Outlet stream process fluid temperature
• Tube Inner Temp, Tube inner wall temperature
 Figure 4.41
 Figure 4.42
Sub pages on the 
Process Fluid page.4-85
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4-86 Fired Heater (Furnace)
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ThIn the Pressures sub-page, the following parameters appear:
• Inlet pressure, inlet stream pressure
• Friction Delta P, friction pressure drop across the tube
• Static Head Delta P, static pressure of the stream
• Outlet Pressure, outlet stream pressure 
Flue Gas Page
The Flue Gas page contains the following sub-pages:
• Temperatures
• Pressures
• Flows
On the Temperatures sub-page, you can view your flue gas 
temperature and Fired Heater inner/outer wall temperatures.
Similarly, the Pressures sub-page displays the flue gas 
pressures, frictional delta P, and static head delta P. The Flow 
sub-page displays the flue gas molar/mass flow.
 Figure 4.434-86
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Th4.3.7 Dynamics Tab
The Dynamics tab contains information pertaining to pressure 
specifications for he dynamic calculations. The information is 
sorted into the following pages:
• Tube Side PF
• Flue Gas PF
• Holdup
Tube Side PF Page
The Tube Side PF page allows you to specify how the pressure 
drop in each pass is calculated. 
The following table outlines the tube side PF options available on 
this page.
 Figure 4.44
Option Description
Use K’s? If this checkbox is selected, the K method is used to 
calculate Delta P across the pass.4-87
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4-88 Fired Heater (Furnace)
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ThFlue Gas PF Page
On the Flue Gas PF page, you can specify how the pressure drop 
in each pass is calculated. 
The following table outlines the tube side PF options available on 
this page.
Use Delta P 
Spec?
If this checkbox is selected, the pressure drop is fixed at 
this specified value.
Calculate K’s If this button is clicked, HYSYS calculates the K required to 
maintain a specified Delta P across a defined flow condition.
 Figure 4.45
Option Description
Use PF K’s If this checkbox is selected, the K method is used to 
calculate Delta P across the pass.
Use Delta P If this checkbox is selected, the pressure drop is fixed at 
this specified value.
Calculate K’s If this button is clicked, HYSYS calculates the K required to 
maintain a specified Delta P across a defined flow condition.
Option Description4-88
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ThHoldup Page
The Holdup page contains information regarding each stream’s 
holdup properties and composition.
4.4 Heat Exchanger
The Heat Exchanger performs two-sided energy and material 
balance calculations. The Heat Exchanger is very flexible, and 
can solve for temperatures, pressures, heat flows (including 
heat loss and heat leak), material stream flows, or UA.
In HYSYS, you can choose the Heat Exchanger Model for your 
analysis. Your choices include an End Point analysis design 
model, an ideal (Ft=1) counter-current Weighted design model, 
a steady state rating method, and a dynamic rating method for 
use in dynamic simulations. The dynamic rating method is 
available as either a Basic or Detailed model, and can also be 
used in Steady State mode for Heat Exchanger rating. The unit 
operation also allows the use of third party Heat Exchanger 
design methods via OLE Extensibility.
 Figure 4.46
Additional Heat Exchanger models, such as TASC and STX, 
are also available. Contact your local AspenTech 
representative for details.
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 
The Individual Holdups 
group contains two drop-
down lists (Zone and 
Holdup) that enable you 
to select and view 
information on individual 
zone and holdup section.4-89
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4-90 Heat Exchanger
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ThThe following are some of the key features of the dynamic Heat 
Exchanger operation:
• A pressure-flow specification option which realistically 
models flow through the Heat Exchanger according to the 
pressure network of the plant. Possible flow reversal 
situations can therefore be modeled.
• The choice between a Basic and Detailed Heat Exchanger 
model. Detailed Heat Exchanger rating information can 
be used to calculate the overall heat transfer coefficient 
and pressure drop across the Heat Exchanger.
• A dynamic holdup model which calculates level in the 
Heat Exchanger shell based on its geometry and 
orientation.
• A heat loss model which accounts for the convective and 
conductive heat transfer that occurs across the Heat 
Exchanger shell wall.
4.4.1 Theory
The Heat Exchanger calculations are based on energy balances 
for the hot and cold fluids.
Steady State
In the following general relations, the hot fluid supplies the Heat 
Exchanger duty to the cold fluid:
where:  
M = fluid mass flow rate
H = enthalpy
Qleak = heat leak
In Dynamic mode, the shell and tube of the Heat Exchanger 
is capable of storing inventory like other dynamic vessel 
operations. The direction of flow of material through the 
Heat Exchanger is governed by the pressures of the 
surrounding unit operations.
(4.28)Balance Error Mcold Hout Hin–[ ]cold Qleak–( ) Mhot Hin Hout–[ ]hot Qloss–( )–=4-90
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ThQloss = heat loss
Balance Error = a Heat Exchanger Specification that equals 
zero for most applications
hot and cold = hot and cold fluids
in and out = inlet and outlet stream
The total heat transferred between the tube and shell sides 
(Heat Exchanger duty) can be defined in terms of the overall 
heat transfer coefficient, the area available for heat exchange, 
and the log mean temperature difference:
where:  
U = overall heat transfer coefficient
A = surface area available for heat transfer
 = log mean temperature difference (LMTD)
Ft = LMTD correction factor
The heat transfer coefficient and the surface area are often 
combined for convenience into a single variable referred to as 
UA. The LMTD and its correction factor are defined in the 
Performance section.
The Heat Exchanger operation allows the heat curve for 
either side of the exchanger to be broken into intervals. 
Rather than calculating the energy transfer based on the 
terminal conditions of the exchanger, it is calculated for each 
of the intervals, then summed to determine the overall 
transfer.
(4.29)Q UAΔTLMFt=
ΔTTM4-91
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ThDynamic
The following general relation applies to the shell side of the 
Basic model Heat Exchanger.
For the tube side:
where:  
Mshell = shell fluid flow rate
Mtube = tube fluid flow rate
 = density
H = enthalpy
Qloss = heat loss
Q = heat transfer from the tube side to the shell side
V = volume shell or tube holdup
The term Qloss represents the heat lost from the shell side of the 
dynamic Heat Exchanger. For more information regarding how 
Qloss is calculated.
Pressure Drop
The pressure drop of the Heat Exchanger can be determined in 
one of three ways:
• Specify the pressure drop.
• Calculate the pressure drop based on the Heat Exchanger 
geometry and configuration.
• Define a pressure flow relation in the Heat Exchanger by 
specifying a k-value.
(4.30)
(4.31)
Mshell Hin Hout–( )shell Qloss– Q+ ρ
d VHout( )shell
dt
---------------------------------=
Mtube Hin Hout–( )tube Q– ρ
d VHout( )tube
dt
--------------------------------=
ρ
Refer to Section 1.3.4 - 
Heat Loss Model in the 
HYSYS Dynamic 
Modeling guide for more 
information.4-92
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ThIf the pressure flow option is chosen for pressure drop 
determination in the Heat Exchanger, a k value is used to relate 
the frictional pressure loss and flow through the exchanger. This 
relation is similar to the general valve equation:
This general flow equation uses the pressure drop across the 
Heat Exchanger without any static head contributions. The 
quantity, P1 - P2, is defined as the frictional pressure loss which 
is used to “size” the Heat Exchanger with a k-value.
Dynamic Specifications
The following tables list the minimum specifications required for 
the Heat Exchanger unit operation to solve in Dynamic mode.
The Basic Heat Exchanger model requires the following dynamic 
specifications:
(4.32)
Specification Description
Volume The tube and shell volumes must be specified. 
Overall UA The Overall UA must be specified.
Pressure 
Drop
Either specify an Overall Delta P or an Overall K-value for 
the Heat Exchanger.
Specify the Pressure Drop calculation method in the 
Dynamic Specifications group on the Specs page of the 
Dynamics tab. You can also specify the Overall Delta P 
values for the shell and tube sides on the Sizing page of the 
Rating tab.
f density k× P1 P2–=4-93
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4-94 Heat Exchanger
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ThThe Detailed Heat Exchanger model requires the following 
dynamic specifications:
4.4.2 Heat Exchanger Property 
View
There are two ways that you can add a Heat Exchanger to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Heat Transfer Equipment radio button.
3. From the list of available unit operations, select Heat 
Exchanger.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Heat Exchanger icon. 
Specification Description
Sizing Data The tube and shell sides of the Heat Exchanger must be 
completely specified on the Sizing page of the Rating tab. 
The overall tube/shell volumes, and the heat transfer 
surface area are calculated from the shell and tube ratings 
information.
Overall UA Either specify an Overall UA or have it calculated from the 
Shell and Tube geometry.
Specify the U calculation method on the Parameters page of 
the Rating tab. The U calculation method can also be 
specified on the Model page of the Dynamics tab.
Pressure 
Drop
Either specify an Overall Delta P or an Overall K-value for 
the Heat Exchanger.
Specify the Pressure Drop calculation method on the 
Parameters page of the Rating tab. You can also specify the 
Pressure Drop calculation method in the Pressure Flow 
Specifications group on the Specs page of the Dynamics 
tab.
Heat Exchanger icon4-94
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ThThe Heat Exchanger property view is displayed.
The Update button enables you to update the heat exchanger 
calculation when in Dynamic mode. For example, if you make a 
configurational change to the heat exchanger, click this button 
to reset the equations around the heat exchanger before 
running the simulation calculation in Dynamic mode.
4.4.3 Design Tab
The Design tab contains the following pages: 
• Connections
• Parameters
• Specs
• User Variables
• Notes
 Figure 4.474-95
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4-96 Heat Exchanger
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ThConnections Page
The Connections page allows you to specify the operation name, 
and the inlet and outlet streams of the shell and tube.
The main flowsheet is the default flowsheet for the Tube and 
Shell side. You can select a subflowsheet on the Tube and/or 
Shell side which allows you to choose inlet and outlet streams 
from that flowsheet. This is useful for processes such as the 
Refrigeration cycle, which require separate fluid packages for 
each side. You can define a subflowsheet with a different fluid 
package, and then connect to the main flowsheet Heat 
Exchanger.
Parameters Page
The Parameters page allows you to select the Heat Exchanger 
Model and specify relevant physical data. The parameters 
appearing on the Parameters page depend on which Heat 
Exchanger Model you select.   
 Figure 4.48
When a heat exchanger is installed as part of a column 
subflowsheet (available when using the Modified HYSIM 
Inside-Out solving method) these Heat Exchanger Models 
are not available. Instead, in the column subflowsheet, the 
heat exchanger is “Calculated from Column” as a simple heat 
and mass balance.4-96
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ThFrom the Heat Exchanger Model drop-down list, select the 
calculation model for the Heat Exchanger. The following Heat 
Exchanger models are available: 
• Exchanger Design (Endpoint)
• Exchanger Design (Weighted)
• Steady State Rating 
• Dynamic Rating
• HTFS - Engine
• TASC Heat Exchanger
For both the Endpoint and Weighted models, you can specify 
whether your Heat Exchanger experiences heat leak/loss. 
• Heat Leak. Loss of cold side duty due to leakage. Duty 
gained to reflect the increase in temperature.
• Heat Loss. Loss of hot side duty due to leakage. Duty 
lost to reflect the decrease in temperature.
The table below describes the radio buttons in the Heat Leak/
Loss group of the Endpoint and Weighted models.      
All Heat Exchanger models allow for the specification of either 
Counter or Co-Current tube flow. 
End Point Model
The End Point model is based on the standard Heat Exchanger 
duty equation (Equation (4.29)) defined in terms of overall 
heat transfer coefficient, area available for heat exchange, and 
the log mean temperature difference (LMTD).
The HTFS - Engine and TASC Heat Exchanger options are only 
available if you have installed TASC.
Radio Button Description
None By default, the None radio button is selected.
Extremes On the hot side, the heat is considered to be “lost” where 
the temperature is highest. Essentially, the top of the heat 
curve is being removed to allow for the heat loss/leak. This 
is the worst possible scenario. On the cold side, the heat is 
gained where the temperature is lowest.
Proportional The heat loss is distributed over all of the intervals.
Refer to the TASC 
Thermal Reference 
guide for more 
information.
Refer to Section 4.4.4 - 
Rating Tab for further 
details.4-97
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4-98 Heat Exchanger
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ThThe main assumptions of the model are as follows:
• Overall heat transfer coefficient, U is constant.
• Specific heats of both shell and tube side streams are 
constant.
The End Point model treats the heat curves for both Heat 
Exchanger sides as linear. For simple problems where there is no 
phase change and Cp is relatively constant, this option may be 
sufficient to model your Heat Exchanger. For non-linear heat 
flow problems, the Weighted model should be used instead.
The following parameters are available when the End Point 
model is selected:
 Figure 4.49
Parameters Description
Tubeside and 
Shellside 
Delta P
The pressure drops (DP) for the tube and shell sides of the 
exchanger can be specified here. If you do not specify the 
Delta P values, HYSYS calculates them from the attached 
stream pressures.
UA The product of the Overall Heat Transfer Coefficient, and 
the Total Area available for heat transfer. The Heat 
Exchanger duty is proportional to the log mean 
temperature difference, where UA is the proportionality 
factor. The UA can either be specified, or calculated by 
HYSYS.
Exchanger 
Geometry
The Exchanger Geometry is used to calculate the Ft Factor 
using the End Point Model. It is not available for the 
weighted model. Refer to the Rating tab for more 
information on the Exchanger Geometry.4-98
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ThWeighted Model
The Weighted model is an excellent model to apply to non-linear 
heat curve problems such as the phase change of pure 
components in one or both Heat Exchanger sides. With the 
Weighted model, the heating curves are broken into intervals, 
and an energy balance is performed along each interval. A LMTD 
and UA are calculated for each interval in the heat curve, and 
summed to calculate the overall exchanger UA.
The Weighted model is available only for counter-current 
exchangers, and is essentially an energy and material balance 
model. The geometry configurations which affect the Ft 
correction factor are not taken into consideration in this model.
When you select the Weighted model, the Parameters page 
appears as shown in the figure below.
 Figure 4.504-99
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4-100 Heat Exchanger
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ThThe following table describes the parameters available on the 
Parameters page when the Weighted model is selected:
Parameters Description
Tubeside and 
Shellside Delta P
The pressure drops (DP) for the tube and shell sides of 
the exchanger can be specified here. If you do not 
specify the DP values, HYSYS calculates them from the 
attached stream pressures.
UA The product of the Overall Heat Transfer Coefficient 
and the Total Area available for heat transfer. The Heat 
Exchanger duty is proportional to the log mean 
temperature difference, where UA is the 
proportionality factor. The UA can either be specified, 
or calculated by HYSYS.
Individual Heat 
Curve Details
For each side of the Heat Exchanger, the following 
parameters appear (all but the Pass Names can be 
modified).
• Pass Name. Identifies the shell and tube side 
according to the names you provided on the 
Connections page.
• Intervals. The number of intervals can be 
specified. For non-linear temperature profiles, 
more intervals are necessary.
• Dew/Bubble Point. Select this checkbox to add 
a point to the heat curve for the dew and/or 
bubble point. If there is a phase change occurring 
in either pass, the appropriate checkbox should 
be selected.
There are three choices for the Step Type:
• Equal Enthalpy. All intervals have an equal 
enthalpy change.
• Equal Temperature. All intervals have an equal 
temperature change.
• Auto Interval. HYSYS determines where points 
should be added to the heat curve. This is 
designed to minimize error using the least 
number of intervals.
The Pressure Profile is updated in the outer iteration 
loop, using one of the following methods:
• Constant dPdH.Maintains constant dPdH during 
update.
• Constant dPdUA.Maintains constant dPdUA 
during update.
• Constant dPdA. Maintains constant dPdA during 
update. This is not currently applicable to the 
Heat Exchanger, as the area is not predicted.
• Inlet Pressure.Pressure is constant and equal to 
the inlet pressure.
• Outlet Pressure. Pressure is constant and equal 
to the outlet pressure.4-100
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Heat Transfer Operations 4-101
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ThSteady State Rating Model
The Steady State Rating model is an extension of the End Point 
model to incorporate a rating calculation, and uses the same 
assumptions as the End Point model. If you provide detailed 
geometry information, you can rate the exchanger using this 
model. As the name suggests, this model is only available for 
steady state rating.
When dealing with linear or nearly linear heat curve problems, 
the Steady State Rating model should be used. Due to the 
solver method incorporated into this rating model, the Steady 
State Rating model can perform calculations exceptionally faster 
than the Dynamic Rating model.
The following parameters are available on the Parameters page 
when the Steady State Rating model is selected:
 Figure 4.51
Parameters Description
Tubeside and 
Shellside 
Delta P
The pressure drops (DP) for the tube and shell sides of the 
exchanger can be specified here. If you do not specify the 
Delta P values, HYSYS calculates them from the attached 
stream pressures.
UA The product of the Overall Heat Transfer Coefficient, and 
the Total Area available for heat transfer. The Heat 
Exchanger duty is proportional to the log mean 
temperature difference, where UA is the proportionality 
factor. The UA can either be specified, or calculated by 
HYSYS.4-101
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4-102 Heat Exchanger
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ThDynamic Rating
Two models are available for Dynamic Rating using the Heat 
Exchanger unit operation: a Basic and a Detailed model. If you 
specify three temperatures or two temperatures and a UA, you 
can rate the exchanger with the Basic model. If you provide 
detailed geometry information, you can rate the exchanger 
using the Detailed model.  
The Basic model is based on the same assumptions as the End 
Point model, which uses the standard Heat Exchanger duty 
equation (Equation (4.29)) defined in terms of overall heat 
transfer coefficient, area available for heat exchange, and the 
log mean temperature difference. The Basic model is actually 
the counterpart of the End Point model for dynamics and 
dynamic rating. The Basic model can also be used for steady 
state Heat Exchanger rating. 
The Detailed model is based on the same assumptions as the 
Weighted model, and divides the Heat Exchanger into a number 
of heat zones, performing an energy balance along each 
interval. This model requires detailed geometry information 
about your Heat Exchanger. The Detailed model is actually the 
counterpart of the Weighted model for dynamics and dynamic 
rating, but can also be used for steady state Heat Exchanger 
rating.
The Specs page no longer appears when Dynamic Rating is 
selected.
 Figure 4.524-102
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Heat Transfer Operations 4-103
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ThThe Basic and Detailed Dynamic Rating models share rating 
information with the Dynamics Heat Exchanger model. Any 
rating information entered using these models is observed in 
Dynamic mode.
Once the Dynamic Rating model is selected, no further 
information is required on the Parameters page of the Design 
tab. You can choose the model (Basic or Detailed) on the 
Parameters page of the Rating tab.
HTFS - Engine
The figure below shows the Parameters page of the Design tab, 
if you select the HTFS - Engine model. Notice that the values in 
the fields appear in black, indicating that they are HYSYS 
calculated values, and you cannot change them in the current 
fields.
To change the variable values shown on this page, you have to 
go to the HTFS - TASC tab on the Heat Exchanger property view. 
Refer to Section 4.4.8 - HTFS-TASC Tab for more information.
Specs Page
The Specs page includes three groups that organize various 
specifications and solver information. The information provided 
on the Specs page is only valid for the Weighted, Endpoint, and 
Steady State Rating models.
 Figure 4.534-103
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4-104 Heat Exchanger
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Th 
Solver Group
The following parameters are listed in the Solver group:
Unknown Variables Group
HYSYS lists all unknown Heat Exchanger variables according to 
your specifications. Once the unit has solved, the values of 
these variables appear.
If you are working with a Dynamic Rating model, the Specs 
page does not appear on the Design tab.
 Figure 4.54
Parameters Details
Tolerance The calculation error tolerance can be set.
Current 
Error
When the current error is less than the calculation tolerance, 
the solution is considered to have converged.
Iterations The current iteration of the outer loop appears. In the outer 
loop, the heat curve is updated and the property package 
calculations are performed. Non-rigorous property 
calculations are performed in the inner loop. Any constraints 
are also considered in the inner loop.4-104
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ThSpecifications Group
The Heat Balance (specified at 0 kJ/h) is considered to be a 
constraint. 
This is a Duty Error spec, which you cannot turn off. Without the 
Heat Balance specification, you could, for example, completely 
specify all four Heat Exchanger streams, and have HYSYS 
calculate the Heat Balance error which would be displayed in the 
Current Value column of the Specifications group.
The UA is also included as a default specification. HYSYS 
displays this as a convenience, since it is a common 
specification. You can either use this spec or deactivate it.
You can view or delete highlighted specifications by using the 
buttons at the right of the group. A specification property view 
appears automatically each time a new spec is created via the 
Add button. The figure below shows a typical property view of a 
specification, which is accessed via the View or Add button.
Each specification property view has the following tabs:
• Parameters
• Summary
The Summary page is used to define whether the specification is 
Active or an Estimate. The Spec Value is also shown on this 
page.
Without the Heat Balance specification, the heat equation is 
not balanced.
 Figure 4.55
Defining the Delta 
Temp spec 
requires two 
stream names 
and a value for 
the specification.4-105
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4-106 Heat Exchanger
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ThAll specifications are one of the following three types:
The specification list allows you to try different combinations of 
the above three specification types. For example, suppose you 
have a number of specifications, and you want to determine 
which ones should be active, which should be estimates and 
which ones should be ignored altogether. By manipulating the 
checkboxes among various specifications, you can test various 
combinations of the three types to see their effect on the 
results.
Information specified on the specification property view also 
appears in the Specifications group.
Specification 
Type
Description
Active An active specification is one that the convergence 
algorithm is trying to meet. An active specification always 
serves as an initial estimate (when the Active checkbox is 
selected, HYSYS automatically selects the Estimate 
checkbox). An active specification exhausts one degree of 
freedom.
An Active specification is one that the convergence 
algorithm is trying to meet. An Active specification is on 
when both checkboxes are selected.
Estimate An Estimate is considered an Inactive specification because 
the convergence algorithm is not trying to satisfy it. To use 
a specification as an estimate only, clear the Active 
checkbox. The value then serves only as an initial estimate 
for the convergence algorithm. An estimate does not use an 
available degree of freedom.
An Estimate is used as an initial “guess” for the 
convergence algorithm, and is considered to be an inactive 
specification.
Completely 
Inactive
To disregard the value of a specification entirely during 
convergence, clear both the Active and Estimate 
checkboxes. By ignoring rather than deleting a 
specification, it remains available if you want to use it later.
A Completely Inactive specification is one that is ignored 
completely by the convergence algorithm, but can be made 
Active or an Estimate at a later time.4-106
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Heat Transfer Operations 4-107
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ThThe available specification types include the following:
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor that allows you to record 
any comments or information regarding the specific unit 
operation or the simulation case in general.
Specification Description
Temperature The temperature of any stream attached to the Heat 
Exchanger. The hot or cold inlet equilibrium temperature 
can also be defined.
• The Hot Inlet Equilibrium temperature is the 
temperature of the inlet hot stream minus the heat 
loss temperature drop. 
• The Cold Inlet Equilibrium temperature is the 
temperature of the inlet cold stream plus the heat leak 
temperature rise.
Delta Temp The temperature difference at the inlet or outlet between 
any two streams attached to the Heat Exchanger. The hot 
or cold inlet equilibrium temperatures (which incorporate 
the heat loss/heat leak with the inlet conditions) can also 
be used.
Minimum 
Approach
Minimum internal temperature approach. The minimum 
temperature difference between the hot and cold stream 
(not necessarily at the inlet or outlet).
UA The overall UA (product of overall heat transfer coefficient 
and heat transfer area).
LMTD The overall log mean temperature difference.
Duty The overall duty, duty error, heat leak or heat loss. The 
duty error should normally be specified as 0 so that the 
heat balance is satisfied. The heat leak and heat loss are 
available as specifications only if the Heat Loss/Leak is set 
to Extremes or Proportional on the Parameters page.
Duty Ratio A duty ratio can be specified between any two of the 
following duties: overall, error, heat loss, and heat leak.
Flow The flowrate of any attached stream (molar, mass or liquid 
volume).
Flow Ratio The ratio of the two inlet stream flowrates. All other ratios 
are either impossible or redundant (in other words, the 
inlet and outlet flowrates on the shell or tube side are 
equal).
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.4-107
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4-108 Heat Exchanger
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Th4.4.4 Rating Tab
The Rating tab contains the following pages:
• Sizing
• Parameters
• Nozzles
• Heat Loss 
Sizing Page
The Sizing page provides Heat Exchanger sizing related 
information. Based on the geometry information, HYSYS is able 
to calculate the pressure drop and the convective heat transfer 
coefficients for both Heat Exchanger sides and rate the 
exchanger. 
The information is grouped under three radio buttons:
• Overall
• Shell
• Tube
The Parameters page is used exclusively by the dynamics 
Heat Exchanger, and only becomes active either in Dynamic 
mode or while using the Dynamic Rating model.4-108
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ThOverall
When you select the Overall radio button, the overall Heat 
Exchanger geometry appears:
In the Configuration group, you can specify whether multiple 
shells are used in the Heat Exchanger design.
The following fields appear, and can be modified in, the 
Configuration group.
 Figure 4.56
Field Description
Number of 
Shell Passes
You have the option of HYSYS performing the calculations 
for Counter Current (ideal with Ft = 1.0) operation, or for a 
specified number of shell passes. Specify the number of 
shell passes to be any integer between 1 and 7. When the 
shell pass number is specified, HYSYS calculates the LMTD 
correction factor (Ft) for the current exchanger design. A 
value lower than 0.8 generally corresponds to inefficient 
design in terms of the use of heat transfer surface. More 
passes or larger temperature differences should be used in 
this case.
For n shell passes, HYSYS solves the heat exchanger on the 
basis that at least 2n tube passes exist. Charts for Shell 
and Tube Exchanger LMTD Correction Factors, as found in 
the GPSA Engineering Data Book, are normally in terms of 
n shell passes and 2n or more tube passes.
Tube flow 
direction can 
be defined as 
either 
Counter or 
Co-Current 
for all heat 
exchanger 
calculation 
models.4-109
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4-110 Heat Exchanger
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ThYou can specify the number of shell and tube passes in the shell 
of the Heat Exchanger. In general, at least 2n tube passes must 
be specified for every n shell pass. The exception is a counter-
current flow Heat Exchanger which has 1 shell pass and one 
tube pass. The orientation can be specified as a vertical or 
horizontal Heat Exchanger. The orientation of the Heat 
Exchanger does not impact the steady state solver, however, it is 
Number of 
Shells in 
Series
If a multiple number of shells are specified in series, the 
configuration is shown as follows:
Number of 
Shells in 
Parallel
If a multiple number of shells are specified in parallel, the 
configuration is shown as follows:
Currently, multiple shells in parallel are not supported in 
HYSYS.
Tube Passes 
per Shell
The number of tube passes per shell. The default setting is 
2 (in other words, the number of tubes equal to 2n, where 
n is the number of shells.)
Exchanger 
Orientation
The exchanger orientation defines whether or not the shell 
is horizontal or vertical. Used only in dynamic simulations.
When the shell orientation is vertical, you can also specify 
whether the shell feed is at the top or bottom via the Shell 
Feed at Bottom checkbox.
The Shell Feed at Bottom checkbox is only visible for the 
vertical oriented exchanger.
First Tube 
Pass Flow 
Direction
Specifies whether or not the tube feed is co-current or 
counter-current.
Elevation 
(base)
The height of the base of the exchanger above the ground. 
Used only in dynamic simulations.
Field Description4-110
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Heat Transfer Operations 4-111
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Thused in the Dynamics Heat Exchanger Model in the calculation of 
liquid level in the shell.
The shape of Heat Exchanger can be specified using the TEMA-
style drop-down lists. The first list contains a list of front end 
stationary head types of the Heat Exchanger. The second list 
contains a list of shell types. The third list contains a list of rear 
end head types. 
In the Calculated Information group, the following Heat 
Exchanger parameters are listed:
• Shell HT Coeff
• Tube HT Coeff
• Overall U
• Overall UA
• Shell DP
• Tube DP
• Heat Trans. Area per Shell
• Tube Volume per Shell
• Shell Volume per Shell
 Figure 4.57
For a more detailed 
discussion of TEMA-style 
shell-and-tube heat 
exchangers, refer to 
page 11-33 of the Perry’s 
Chemical Engineers’ 
Handbook (1997 
edition).4-111
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4-112 Heat Exchanger
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ThShell
Selecting the Shell radio button allows you to specify the shell 
configuration and the baffle arrangement in each shell.
In the Shell and Tube Bundle Data group, you can specify 
whether multiple shells are used in the Heat Exchanger design. 
The following fields appear, and can be modified in, the Shell 
and Tube Bundle Data group.
 Figure 4.58
Field Description
Shell Diameter Diameter of the shell(s).
Number of 
Tubes per Shell
Number of tubes per shell. You can change the value in 
this field.
Tube Pitch Shortest distance between the centres of two adjacent 
tubes.
Tube Layout 
Angle
In HYSYS, the tubes in a single shell can be arranged in 
four different symmetrical patterns:
• Triangular (30°)
• Triangular Rotated (60°)
• Square (90°)
• Square Rotated (45°)
For more information regarding the benefits of different 
tube layout angles, refer to page 139 of Process Heat 
Transfer by Donald Q. Kern (1965)
Shell Fouling The shell fouling factor is taken into account in the 
calculation of the overall heat transfer coefficient, UA.4-112
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ThThe following fields appear, and can be modified in, the Shell 
Baffles group:
Tube
Selecting the Tube radio button allows you to specify the tube 
geometry information in each shell.
The Dimensions group allows you to specify the following tube 
geometric parameters:
Field Description
Shell Baffle Type You can choose from four different baffle types:
• Single
• Double
• Triple
• Grid 
Shell Baffle 
Orientation
You can choose whether the baffles are aligned 
horizontally or vertically along the inner shell wall.
Baffle cut 
(Area%)
You can specify the percent area where the liquid flows 
through relative to the cross sectional area of the shell. 
The baffle cut is expressed as a percent of net free 
area. The net free area is defined as the total cross-
sectional area in the flow direction parallel to the tubes 
minus the area blocked off by the tubes (essentially 
the percentage of open area).
Baffle Spacing You can specify the space between each baffle.
 Figure 4.59
Field Description
Outer Tube Diameter (OD)
Inner Tube Diameter (ID)
Tube Thickness
Two of the three listed parameters must be 
specified to characterize the tube width 
dimensions.
Tube Length Heat transfer length of one tube in a single Heat 
Exchanger shell. 
This value is not the actual tube length.4-113
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4-114 Heat Exchanger
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ThIn the Tube Properties group, the following metal tube heat 
transfer properties must be specified:
• Tube Fouling Factor
• Thermal Conductivity
• Wall Specific Heat Capacity, Cp
• Wall Density
Parameters Page
The Parameters page of the Rating tab is used to define rating 
parameters for the Dynamic Rating model. On the Parameters 
page, you can specify either a Basic model or a Detailed model. 
For the Basic model, you must define the Heat Exchanger overall 
UA and pressure drop across the shell and tube. For the Detailed 
model, you must define the geometry and heat transfer 
parameters of both the shell and tube sides in the Heat 
Exchanger operation. In order for either the Basic or Detailed 
Heat Exchanger Model to completely solve, the Parameters page 
must be completed.
Basic Model
When you select the Basic model radio button on the Parameters 
page in Dynamic mode, the following property view appears.
The Dimensions group contains the following information:
• Tube Volume
• Shell Volume
• Elevation (Base)
 Figure 4.604-114
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ThThe tube volume, shell volume, and heat transfer area are 
calculated from Shell and Tube properties specified by selecting 
the Shell and Tube radio buttons on the Sizing page. The 
elevation of the base of the Heat Exchanger can be specified but 
does not impact the steady state solver. 
The Prevent Temperature Cross checkbox is used to activate 
additional model options when selected. These additional model 
options prevent temperature crosses by automatically reducing 
the heat transfer rate slowly.
The Parameters group includes the following Heat Exchanger 
parameters. All but the correction factor, F, can be modified:
Field Description
Overall UA The product of the Overall Heat Transfer Coefficient, and 
the Total Area available for heat transfer. The Heat 
Exchanger duty is proportional to the log mean 
temperature difference, where UA is the proportionality 
factor. The UA can either be specified, or calculated by 
HYSYS.
Tubeside and 
Shellside 
Delta P
The pressure drops (DP) for the tube and shell sides of the 
exchanger can be specified here. If you do not specify the 
DP values, HYSYS calculates them from the attached 
stream pressures.4-115
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ThDetailed Model
The Detailed model option allows you to specify the zone 
information, heat transfer coefficient, and Delta P details. When 
you select the Detailed model radio button on the Parameters 
page, the following property view appears.
Zone Information
HYSYS can partition the Heat Exchanger into discrete multiple 
sections called zones. Because shell and tube stream conditions 
do not remain constant across the operation, the heat transfer 
parameters are not the same along the length of the Heat 
Exchanger. By dividing the Heat Exchanger into zones, you can 
make different heat transfer specifications for individual zones, 
and therefore more accurately model an actual Heat Exchanger.
In the Zone Information group you can specify the following:
 Figure 4.61
Field Description
Zones per 
Shell Pass
Enter the number of zones you want for one shell. The total 
number of zones in a Heat Exchanger shell is calculated as:
Zone 
Fraction
The fraction of space the zone occupies relative to the total 
shell volume. HYSYS automatically sets each zone to have 
the same volume. You can modify the zone fractions to 
occupy a larger or smaller proportion of the total volume. 
Click the Normalize Zone Fractions button in order to adjust 
the sum of fractions to equal one.
Total Zones Total Shell Passes Zones⋅=4-116
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ThHeat Transfer Coefficients
The Heat Transfer Coefficients group contains information 
regarding the calculation of the overall heat transfer coefficient, 
UA, and local heat transfer coefficients for the fluid in the tube, 
hi, and the fluid surrounding the tube, ho. The heat transfer 
coefficients can be determined in one of two ways:
• The heat transfer coefficients can be specified using the 
rating information provided on the Parameters page and 
the stream conditions.
• You can specify the heat transfer coefficients. 
For fluids without phase change, the local heat transfer 
coefficient, hi, is calculated according to the Sieder-Tate 
correlation:
where:  
Gi = mass velocity of the fluid in the tubes (velocity*density)
 = viscosity of the fluid in the tube
 = viscosity of the fluid inside tubes, at the tube wall
Cp,i = specific heat capacity of the fluid inside the tube
The relationship between the local heat transfer coefficients, and 
the overall heat transfer coefficient is shown in Equation 
(4.34).
where:  
U = overall heat transfer coefficient
ho = local heat transfer coefficient outside tube
hi = local heat transfer coefficient inside tube
(4.33)
(4.34)
hi
0.027km
Di
-------------------
DiGi
μi
-----------⎝ ⎠
⎛ ⎞
0.8 Cp i, μi
km
--------------⎝ ⎠
⎛ ⎞
1 3⁄ μi
μi w,
---------⎝ ⎠
⎛ ⎞
0.14
=
μi
μi w,
U 1
1
ho
---- ro rw
Do
Di
------ ri
1
hi
---+⎝ ⎠
⎛ ⎞+ + +
--------------------------------------------------------------------=4-117
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4-118 Heat Exchanger
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Thro = fouling factor outside tube
ri = fouling factor inside tube
rw = tube wall resistance
Do = outside diameter of tube
Di = inside diameter of tube
The Heat Transfer coefficients group contains the following 
information:
Delta P
The Delta P group contains information regarding the calculation 
of the shell and tube pressure drop across the exchanger. In 
Steady State mode, the pressure drop across either the shell or 
tube side of the Heat Exchanger can be calculated in one of two 
ways:
• The pressure drop can be calculated from the rating 
information provided in the Sizing page and the stream 
conditions.
• The pressure drop can be specified.
Field Description
Shell/Tube Heat 
Transfer 
Coefficient
The local Heat Transfer Coefficients, ho and hi, can be 
specified or calculated.
Shell/Tube HT 
Coefficient 
Calculator
The Heat Transfer Coefficient Calculator allows you to 
either specify or calculate the local Heat Transfer 
Coefficients. Specify the cell with one of following 
options:
• Shell & Tube. The local heat transfer 
coefficients, ho and hi, are calculated using the 
heat exchange rating information and 
correlations.
• U specified. The local heat transfer coefficients, 
ho and hi, are specified by you.4-118
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ThThe Delta P group contains the following information:
Detailed Heat Model Properties
When you click the Specify Parameters for Individual Zones 
button, the Detailed Heat Model Properties property view 
appears. The Detailed Heat Model Properties property view 
displays the detailed heat transfer parameters and holdup 
conditions for each zone. 
HYSYS uses the following terms to describe different locations 
within the Heat Exchanger.
Field Description
Shell/Tube 
Delta P
The pressure drop across the Shell/Tube side of the Heat 
Exchanger can be specified or calculated.
Shell/Tube 
Delta P 
Calculator
The Shell/Tube Delta P Calculator allows you to either 
specify or calculate the shell/tube pressure drop across the 
Heat Exchanger. Specify the cell with one of following 
options:
• Shell & Tube Delta P Calculator. The pressure drop 
is calculated using the Heat Exchanger rating 
information and correlations.
• User specified. The pressure drop is specified by 
you.
• Non specified. This option is only applicable in 
Dynamic mode. Pressure drop across the Heat 
Exchanger is calculated from a pressure flow relation.
Location Term Description
Zone HYSYS represents the zone using the letter “Z”. Zones 
are numbered starting from 0. For instance, if there 
are 3 zones in a Heat Exchanger, the zones are 
labeled: Z0, Z1, and Z2.
Holdup HYSYS represents the holdup within each zone with the 
letter “H”. Holdups are numbered starting from 0. 
“Holdup 0” is always the holdup of the shell within the 
zone. Holdups 1 through n represents the n tube 
holdups existing in the zone. 
Tube Location HYSYS represents tube locations using the letters “TH”. 
Tube locations occur at the interface of each zone. 
Depending on the number of tube passes per shell 
pass, there can be several tube locations within a 
particular zone. For instance, 2 tube locations exist for 
each zone in a Heat Exchanger with 1 shell pass and 2 
tube passes. Tube locations are numbered starting 
from 1.4-119
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4-120 Heat Exchanger
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ThConsider a shell and tube Heat Exchanger with 3 zones, 1 shell 
pass, and 2 tube passes. The following diagram labels zones, 
tube locations, and hold-ups within the Heat Exchanger:
Heat Transfer (Individual) Tab
Information regarding the heat transfer elements of each tube 
location in the Heat Exchanger appears on the Heat Transfer 
(Individual) tab. 
 Figure 4.62
 Figure 4.634-120
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ThHeat transfer from the fluid in the tube to the fluid in the shell 
occurs through a series of heat transfer resistances or elements. 
There are two convective elements, and one conductive element 
associated with each tube location.
This tab organizes all the heat transfer elements for each tube 
location in one spreadsheet. You can choose whether Conductive 
or Convective elements will appear by selecting the appropriate 
element type in the Heat Transfer Type drop-down list.
The following is a list of possible elements for each tube 
location:
Heat Transfer (Global) Tab
The Heat Transfer (Global) tab displays the heat transfer 
elements for the entire Heat Exchanger. You can choose whether 
the overall Conductive or Convective elements are to appear by 
selecting the appropriate element type in the Heat Transfer Type 
drop-down list.
Tabular Results Tab
The Tabular Results tab displays the following stream properties 
for the shell and tube fluid flow paths. The feed and exit stream 
conditions appear for each zone.
• Temperature
• Pressure
• Vapour Fraction
Heat Transfer 
Element
Description
Convective Element The Shell Side element is associated with the local 
heat transfer coefficient, ho, around the tube. The 
Tube Side is associated with the local heat transfer 
coefficient, hi, inside the tube.These local heat 
transfer coefficients can be calculated by HYSYS or 
modified by you.
Conductive Element This element is associated with the conduction of 
heat through the metal wall of the tube. The 
conductivity of the tube metal, and the inside and 
outside metal wall temperatures appear. You can 
modify the conductivity.4-121
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4-122 Heat Exchanger
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Th• Molar Flow
• Enthalpy
• Cumulative UA
• Cumulative Heat Flow
• Length (into Heat Exchanger)
Specs (Individual) Tab
The Specs (Individual) tab displays the pressure drop 
specifications for each shell and tube holdup in one spreadsheet.
The Pressure Flow K and Use Pressure Flow K columns are 
applicable only in Dynamic mode.
You can choose whether the flow path is shell or tube side by 
selecting the appropriate flow path in the Display which flow 
path? drop-down list.
 Figure 4.64
You can choose whether the shell or tube side appears by 
selecting the appropriate flow path in the Display which flow 
path? drop-down list.4-122
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ThSpecs (Global) Tab
The Specs (Global) tab displays the pressure drop specifications 
for the entire shell and tube holdups. The Pressure Flow K and 
Use Pressure Flow K columns are applicable only in Dynamic 
mode.
You can choose whether the shell or tube side appears by 
selecting the appropriate flow path in the Display which flow 
path? drop-down list.
Plots Tab
The information displayed on the Plots tab is a graphical 
representation of the parameters provided on the Tabular 
Results tab. You can plot the following variables for the shell and 
tube side of the Heat Exchanger:
• Vapour Fraction
• Molar Flow
• Enthalpy
• Cumulative UA
• Heat Flow 
• Length
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. 
The placement of feed and product nozzles on the Detailed 
Dynamic Heat Exchanger operation has physical meaning. The 
exit stream’s composition depends on the exit stream nozzle’s 
location and diameter in relation to the physical holdup level in 
the vessel. If the product nozzle is located below the liquid level 
in the vessel, the exit stream draws material from the liquid 
holdup. If the product nozzle is located above the liquid level, 
the exit stream draws material from the vapour holdup. 
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.4-123
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ThIf the liquid level sits across a nozzle, the mole fraction of liquid 
in the product stream varies linearly with how far up the nozzle 
the liquid is.
Essentially, all vessel operations in HYSYS are treated the same. 
The compositions and phase fractions of each product stream 
depend solely on the relative levels of each phase in the holdup 
and the placement of the product nozzles, so a vapour product 
nozzle does not necessarily produce pure vapour. A 3-phase 
separator may not produce two distinct liquid phase products 
from its product nozzles.
Heat Loss Page
The Heat Loss page contains heat loss parameters which 
characterize the amount of heat lost across the vessel wall. You 
can choose either to have no heat loss model, a Simple heat loss 
model or a Detailed heat loss model.
Simple Heat Loss Model
 Figure 4.654-124
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ThWhen you select the Simple radio button, the following 
parameters appear:
• Overall U
• Ambient Temperature
• Overall Heat Transfer Area
• Heat Flow
Detailed Heat Loss Model
The Detailed model allows you to specify more detailed heat 
transfer parameters. The HYSYS Dynamics license is required to 
use the Detailed Heat Loss model found on this page. 
4.4.5  Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Heat Exchanger unit operation. 
To view the stream parameters broken down per stream phase, 
open the Worksheet tab of the stream property view.
4.4.6 Performance Tab
The Performance tab has pages that display the results of the 
Heat Exchanger calculations in overall performance parameters, 
as well as using plots and tables.
The Performance tab contains the following pages:
• Details
• Plots
• Tables
• Setup
• Error Msg
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.6.1 - 
Detailed Heat Model in 
the HYSYS Dynamic 
Modeling guide for more 
information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.4-125
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ThDetails Page
The information from the Details page appears in the figure 
below. 
Overall Performance Group
The Overall and Detailed performance groups contain the 
following parameters that are calculated by HYSYS:
 Figure 4.66
The appearance of this page is slightly different for the 
Dynamic Rating model.
Parameter Description
Duty Heat flow from the hot stream to the cold stream.
Heat Leak Loss of cold side duty due to leakage. Duty gained to reflect 
the increase in temperature.
Heat Loss Loss of the hot side duty to leakage. The overall duty plus 
the heat loss is equal to the individual hot stream duty 
defined on the Tables page.
UA Product of the Overall Heat Transfer Coefficient, and the 
Total Area available for heat transfer. The UA is equal to the 
overall duty divided by the LMTD.
 Minimum 
Approach
The minimum temperature difference between the hot and 
cold stream.
Mean Temp 
Driving Force
The average temperature difference between the hot and 
cold stream.
Dynamic Rating
Steady State Rating4-126
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ThUncorrected LMTD equation:
where:   
LMTD The uncorrected LMTD multiplied by the Ft factor. For the 
Weighted Rating Method, the uncorrected LMTD equals the 
effective LMTD.
UA Curvature 
Error
The LMTD is ordinarily calculated using constant heat 
capacity. An LMTD can also be calculated using linear heat 
capacity. In either case, a different UA is predicted. The UA 
Curvature Error reflects the difference between these UAs.
Hot Pinch 
Temperature
The hot stream temperature at the minimum approach.
Cold Pinch 
Temperature
The cold stream temperature at the minimum approach.
Ft Factor The LMTD (log mean temperature difference) correction 
factor, Ft, is calculated as a function of the Number of Shell 
Passes and the temperature approaches. For a counter-
current Heat Exchanger, Ft is 1.0. For the Weighted rating 
method, Ft = 1.
Uncorrected 
LMTD
(Applicable only for the End Point method) - The LMTD is 
calculated in terms of the temperature approaches 
(terminal temperature differences) in the exchanger, using 
the Equation (4.35).
(4.35)
Parameter Description
ΔTLM
ΔT1 ΔT2–
ΔT1 ΔT2( )⁄( )ln
--------------------------------------=
ΔT1 Thot out, Tcold in,–=
ΔT2 Thot in, Tcold o, ut–=4-127
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ThPlots Page
You can plot curves for the hot and/or cold fluid. Use the Plot 
checkboxes to specify which side(s) of the exchanger should be 
plotted. 
The following default variables can be plotted along either the X 
or Y-axis:
• Temperature
• UA
• Delta T
• Enthalpy
• Pressure
• Heat Flow
Select the combination from the Plot Type drop-down list. To 
Plot other available variables, you need to add them on the 
Setup page. Once the variables are added, they are available in 
the X and Y drop-down lists.
 Figure 4.67
You can modify the appearance of the plot via the Graph 
Control property view.
Refer to Section 1.3.1 - 
Graph Control Property 
View for more 
information.4-128
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ThTables Page
On the Tables page, you can view (default variables) interval 
temperature, pressure, heat flow, enthalpy, UA, and vapour 
fraction for each side of the Exchanger in a tabular format. 
Select either the Shell Side or Tube Side radio button. 
To view other available variables, you need to add them on the 
Setup page. Variables are displayed based on Phase Viewing 
Options selected.
Setup Page
The Setup page allows you to filter and add variables to be 
viewed on the Plots and Tables pages.
The variables that are listed in the Selected Viewing Variables 
group are available in the X and Y drop down list for plotting on 
the Plots page. The variables are also available for tabular plot 
results on the Tables page based on the Phase Viewing Options 
selected.
Error Msg Page
The Error Msg page contains a list of the warning messages on 
the Heat Exchanger. You cannot add comments to this page. Use 
it to see if there are any warnings in modeling the Heat 
Exchanger. 4-129
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Th4.4.7 Dynamics Tab
The Dynamics tab contains the following pages:
• Model
• Specs
• Holdup
• Stripchart
Any information specified on the Rating tab also appears in the 
Dynamics tab.
Model Page
In the Model page, you can specify whether HYSYS uses a Basic 
or Detailed model.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab.
 Figure 4.684-130
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ThBasic Model
The Model Parameters group contains the following information 
for the Heat Exchanger unit operation:
The Summary group contains information regarding the duty of 
the Heat Exchanger shell and tube sides.
Field Description
Tube/Shell 
Volume
The volume of the shell and tube must be specified in the Basic model.
Elevation The elevation is significant in the calculation of static head around and in 
the Heat Exchanger. 
Overall UA Product of the Overall Heat Transfer Coefficient and the Total Area 
available for heat transfer. The Heat Exchanger duty is proportional to 
the log mean temperature difference, where UA is the proportionality 
factor. The UA must be specified if the Basic model is used.
Shell/Tube UA 
Reference Flow
Since UA depends on flow, these parameters allow you to set a reference 
point that uses HYSYS to calculate a more realistic UA value. If no 
reference point is set then UA is fixed.
If the UA is specified, the specified UA value does not change during the 
simulation. The UA value that is used, however, does change if a 
Reference Flow is specified. Basically, as in most heat transfer 
correlation's, the heat transfer coefficient is proportional to 
the . The equation below is used to determine the UA 
used:
(4.36)
Reference flows generally help to stabilize the system when you do shut 
downs and startups as well.
Minimum Flow 
Scale Factor
The ratio of mass flow at time t to reference mass flow is also known as 
flow scaled factor. The minimum flow scaled factor is the lowest value 
which the ratio is anticipated at low flow regions. This value can be 
expressed in a positive value or negative value. 
• A positive value ensures that some heat transfer still takes place at 
very low flows. 
• A negative value ignores heat transfer at very low flows.
A negative factor is often used in shut downs if you are not interested in 
the results or run into problems shutting down an exchanger.
If the Minimum Flow Scale Factor is specified, the Equations (4.36) 
uses the  ratio if the ratio is greater than the Min 
Flow Scale Factor. Otherwise the Min Flow Scale Factor is used. 
In some cases you can use a negative value for minimum flow scale 
factor. If you use -0.1, then if the scale factor goes below 0.1, the 
Minimum Flow Scale Factor uses 0.
mass flow ratio( )0.8
UAused UAspecified
mass flowcurrent
mass flowreference
-----------------------------------------⎝ ⎠
⎛ ⎞
0.8
×=
mass flowcurrent
mass flowreference
-----------------------------------------⎝ ⎠
⎛ ⎞
0.84-131
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ThDetailed Model
When you select the Detailed radio button, a summary of the 
rating information specified on the Rating tab appears.
The Model Data group contains the following information:
The Model Parameters group contains the local and overall heat 
transfer coefficients for the Heat Exchanger. Depending on how 
 Figure 4.69
Field Description
Tube/Shell 
Volume
The volume of the shell and tube is calculated from the 
Heat Exchanger rating information.
Heat Transfer 
Area
The heat transfer area is calculated from the Heat 
Exchanger rating information.
Elevation The elevation is significant in the calculation of static 
head around and in the Heat Exchanger.
Shell/Tube 
Passes
You can specify the number of tube and shell passes in 
the shell of the Heat Exchanger. In general, at least 2n 
tube passes must be specified for every n shell pass. 
The exception is a counter-current flow Heat 
Exchanger which has 1 shell pass and one tube pass
Orientation The orientation may be specified as a vertical or 
horizontal Heat Exchanger. The orientation of the Heat 
Exchanger does not impact the steady state solver. 
However, it used in the dynamic Heat Exchanger in the 
calculation of liquid level in the shell.
Zones per Shell 
Pass
Enter the number of zones you would like for one shell 
pass. The total number of zones in a Heat Exchanger 
shell is calculated as:
Total Zones # of Shells Zones
Shell Pass
---------------------------⋅=4-132
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Ththe Heat Transfer Coefficient Calculator is set on the Parameters 
page of the Rating tab, the local and overall heat transfer 
coefficients can either be calculated or specified in the Model 
Parameters group. 
The Startup Level group appears only if the Heat Exchanger is 
specified with a single shell and/or tube pass having only one 
zone. The Startup level cannot be set for multiple shell and/or 
tube pass exchangers for multiple shell or tube passes. You can 
specify an initial liquid level percent for the shell or tube 
holdups. This initial liquid level percent is used only if the 
simulation case re-initializes.
Specs Page
The Specs page contains information regarding the calculation 
of pressure drop across the Heat Exchanger.
HT Coefficient 
Calculator Setting
Description
Shell & Tube Overall heat transfer coefficient, U, is calculated 
using the exchanger rating information.
U Specified Overall heat transfer coefficient, U, is specified by 
you.
The information displayed on the Specs page depends on the 
model (Basic or Detailed) selected on the Model page.4-133
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ThBasic Model
When you select the Basic model radio button on the Model 
page, the Specs page appears as follows.
The pressure drop across any pass in the Heat Exchanger 
operation can be determined in one of two ways:
• Specify the pressure drop.
• Define a pressure flow relation for each pass by 
specifying a k value.
The following parameters are used to specify the pressure drop 
for the Heat Exchanger.
 Figure 4.70
Dynamic 
Specification
Description
Shell/Tube 
Delta P
The pressure drop across the Shell/Tube side of the Heat 
Exchanger may be specified (checkbox active) of calculated 
(checkbox inactive).
k Activate this option if to have the Pressure Flow k values 
used in the calculation of pressure drop.4-134
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ThEffectively, the k Reference Flow results in a more linear 
relationship between flow and pressure drop, and this is used to 
increase model stability during startup and shutdown where the 
flows are low.
Use the Calculate k button to calculate a k value based on the 
Delta P and k Reference flow. Ensure that there is a non zero 
pressure drop across the Heat Exchanger before you click the 
Calculate k button.
Detailed Model
When you select the Basic model radio button on the Model 
page, the Specs page appears as follows.
k Reference 
Flow
If the pressure flow option is chosen the k value is 
calculated based on two criteria. If the flow of the system is 
larger than the k Reference Flow, the k value remains 
unchanged. If the flow of the system is smaller than the k 
Reference Flow the k value is given by:
where:
Factor = value is determined by HYSYS internally to 
take into consideration the flow and pressure drop 
relationship at low flow regions.
At low flow range, it is recommended that the k reference 
flow is taken as 40% of steady state design flow for better 
pressure flow stability.
 Figure 4.71
Dynamic 
Specification
Description
kused kspecified Factor×=4-135
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ThThe following parameters are used to specify the pressure drop 
for the Heat Exchanger.
Clicking the K Summary button opens the Detailed Heat Model 
Properties property view. 
Holdup Page
The Holdup page contains information regarding the shell and 
tube holdup properties, composition, and amount.
Dynamic 
Specification
Description
Pressure 
Flow k
The k-value defines the relationship between the flow 
through the shell or tube holdup and the pressure of the 
surrounding streams. You can either specify the k-value or 
have it calculated from the stream conditions surrounding 
the Heat Exchanger. you can “size” the exchanger with a k-
value by clicking the Calculate K’s button. Ensure that 
there is a non zero pressure drop across the Heat 
Exchanger before the Calculate k button is clicked.
Pressure 
Flow Option
Activate this option to have the Pressure Flow k values used 
in the calculation of pressure drop. If the Pressure Flow 
option is selected, the Shell/Tube Delta P calculator must 
also be set to non specified.
Shell/Tube 
Delta P
The pressure drop across the Shell/Tube side of the Heat 
Exchanger may be specified or calculated.
Shell/Tube 
Delta P 
Calculator
The Shell/Tube Delta P calculator allows you to either 
specify or calculate the shell/tube pressure drop across the 
Heat Exchanger. Specify the cell with one of the following 
options:
• Shell & Tube Delta P Calculator. The pressure drop 
is calculated using the Heat Exchanger rating 
information and correlations.
• user specified. The pressure drop is specified by you.
• not specified. This option is only applicable in 
Dynamic mode. Pressure drop across the Heat 
Exchanger is calculated from a pressure flow 
relationship. You must specify a k-value and activate 
the Pressure Flow option to use this calculator.
Refer to Detailed Heat 
Model Properties 
section for more 
information.
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 4-136
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ThBasic Model
When you select the Basic model radio button on the Model 
page, the Holdup page appears as follows.
The Shell Holdup group and Tube Holdup group contain 
information regarding the shell and tube side holdup 
parameters.
Detailed Model
When you select the Detailed model radio button on the Model 
page, the Holdup page appears as follows.
 Figure 4.72
 Figure 4.734-137
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4-138 Heat Exchanger
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ThThe Overall Holdup Details group contains information regarding 
the shell and tube side holdup parameters. 
The Individual Zone Holdups group contains detailed holdup 
properties for every layer in each zone of the Heat Exchanger 
unit operation. In order to view the advanced properties for 
individual holdups, you must first choose the individual holdup.
To choose individual holdups you must specify the Zone and 
Layer in the corresponding drop-down lists. 
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
4.4.8 HTFS-TASC Tab
When you select the HTFS - Engine model on the Parameters 
page of the Design tab, the HTFS-TASC tab appears as shown in 
the figure below:
 Figure 4.74
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.4-138
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ThThe HTFS-TASC tab contains the following pages:
• Exchanger
• Process
• Bundle
• Nozzles
• Enhanced Surfaces
• Design and Material
• Methods
• Results
The HTFS-TASC tab also contains two buttons:
• Import. Allows you to import values from TASC into the 
pages of the tab.
• Export. Allows you to export the information provided 
within this tab to TASC.
Exchanger Page
The Exchanger page allows you to input parameters that define 
the geometric configuration of the Heat Exchanger.
After entering a basic configuration of the Heat Exchanger, you 
can specify detailed information.
 Figure 4.754-139
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4-140 Heat Exchanger
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ThBasics Data
For the Basics data, you can enter the following information:
Entry Description
Front End Head 
Type
You can select the type of front end head for your heat 
exchanger using the drop-down list. 
The type of head selected has no significant effect on 
the heat exchanger thermal or pressure drop 
performance, as calculated by TASC. It only affects the 
heat exchanger weight.
Shell Type You can select the type of shells for the heat exchanger 
using the drop-down list.
Rear End Head 
Type
You can select the type of rear end head for your heat 
exchanger using the drop-down list. 
Shell Internal 
Diameter
You can enter the internal diameter of the shell in this 
cell.
Tube Outside 
Diameter
You can enter the outside diameter of the tube in this 
cell.
Tube Length 
(Straight)
You can enter the length of the tube in this cell.
Effective Tube 
Count
You can enter the number of tubes in the heat 
exchanger in this cell.
If you did not enter any value in this cell, TASC derives 
an exact tube count while setting up the Tube Bundle 
Layout.
Orientation You can select from three types of orientation for your 
heat exchanger in the drop-down list:
• Default (Horiz.)
• Horizontal
• Vertical
Hot Side You can select which side is the hot side in your heat 
exchanger from the drop-down list. There are three 
selections:
• Not yet set
• Tubeside hot
• Shell-side hot
Countercurrent 
in 1st Pass
You can select whether countercurrent occurs in the 
first pass from the drop-down list. There are three 
selections:
• Not set
• Yes
• No (co-current)
No. Exchangers 
in Parallel
You can specify how many heat exchangers are parallel 
to the current heat exchanger in this cell.
No. Exchangers 
in Series
You can specify how many heat exchangers are in 
series to the current heat exchanger in this cell.
No. of Tubeside 
Passes
You can specify how many tubeside passes occur in the 
heat exchanger in this cell.
Refer to the TASC 
Thermal Reference 
guide for more 
information about the 
selections available.4-140
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ThDetails Data
For the Details data, you can enter the following information:
Entry Description
Tubeplate 
Thickness
You can specify the tubeplate thickness in this cell.
Shell Thickness You can specify the shell thickness in this cell.
FFE/Reflux You can select the special type of exchanger using the 
drop-down list. There are four selections:
• Default (normal)
• Normal exchanger
• Falling Film Evap
• Reflux Condenser
Fixed Head (Vert 
Exchgr)
You can select the location of the fixed end head from 
the drop-down list. There are three selections:
• Default/horiz
• Top
• Bottom
The Top and Bottom selections only apply to vertical 
shells.
Area Fraction 
Submerged
You can enter the area fraction on the tubes that may 
be submerged under condensate in this cell.
This value only applies to horizontal shellside 
condensers and if there is a lute or geometric feature 
that causes tubes to be submerged.
M Shell Pitch You can enter the shell pitch for double-pipe U-tube 
exchangers or Multitube hairpin exchangers in this cell. 
The value is used to determine the U-bend heat 
transfer area.
Kettle Large 
Shell Diameter
You can enter the internal diameter of the larger part 
of the shell of a kettle reboiler in this cell.
Weir Height Over 
Bundle
You can enter the height of the weir above the top of 
the bundle in this cell. This value is used to define the 
head of liquid providing the driving force for re-
circulation within a kettle.
If no value is entered, HYSYS assumes the value is 
zero. The top of the weir is assumed to be level with 
the top of the outer tube limit circle of the bundle.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-141
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4-142 Heat Exchanger
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ThProcess Page
The Process page allows you to specify the estimate pressure 
drop, fouling resistance, and heat load.
Bundle Page
The Bundle page allows you to specify the bundle, tube, and 
baffles configurations. The radio buttons in the Bundle Data 
group controls which configuration appears on the page.
• Bundle
• Tubes
• Baffles
 Figure 4.76
The estimated heat load is used as a starting point to do the 
simulation calculation.4-142
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ThBundle Configuration
If you select the Bundle radio button in the Bundle Data group, 
the Bundle page appears as shown in the figure below:
The configuration information you can specify for the bundle is 
sorted into four groups:
• Size
• U-Tubes
• Layout
• Pass Partitions
Size Group
The Size group allows you to specify information used to 
calculate the size of the bundle.
 Figure 4.77
Specification Description
Effective Tube 
Count
Number of tubes in the heat exchanger.
The Effective Tube Count field is linked to the Effective 
Tube Count field on the Exchanger page. Any changes 
in either fields propagates to the other.
No of Blocked Off 
Tubes
Number of blocked off tubes.
Bundle-Shell 
DIam Clear
Diametral clearance between the tube bundle (outer 
limit diameter) and the shell wall. This value is used to 
determine the fraction of the shellside flow which by 
passes around the bundle. For zero clearance, enter 0.4-143
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ThU-Tubes Group
The U-tubes group allows you to select the configuration of the 
U-tubes.
Layout Group
The Layout group allows you to specify information used to 
design the layout of the bundle.
First Row to 
Shell
Specify the distance between the centres of the first 
row tubes to the shell. The first tube row is that 
nearest the inlet nozzle.
Last Row to Shell Specify the distance between the centres of the last 
row tubes to the shell. The last tube row is that 
furthest from the inlet nozzle.
Specification Description
U-Bend 
Orientation
You can select the type of U-bend orientation from the 
drop-down list. There are three selections:
• Default
• Horizontal
• Vertical
U-Bend Heat 
Transfer
You can select whether to include or exclude the heat 
transfer that occurs in the U-tube using the drop-down list. 
There are three selections:
• Default
• Allow for U-bend
• Ignore U-bend
Specification Description
Normal/Full 
Bundle
You can select what type of bundle to use from the 
drop-down list. There are three selections:
• Default (Normal)
• Normal Bundle
• Full Bundle
Tubes in Window You can select whether you want tubes in the window 
or not from the drop-down list. There are three 
selections:
• Default (Yes)
• Yes
• No
Specification Description
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.
Refer to TASC Thermal 
Reference guide for 
information about the 
selections available.4-144
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ThPass Partitions Group
The Pass Partitions group allows you to specify information used 
to configure the pass partition.
Bundle Band 
Orientation
You can select the bundle band orientation from the 
drop-down list. There are three selections:
• Default (horizontal)
• Horizontal
• Vertical
Tube Alignment You can select the tube alignment from the drop-down 
list. There are four selections:
• Default (if yes 45 90)
• Fully aligned
• Unaligned
• Part aligned
Layout 
Symmetry
You can select the layout symmetry from the drop-
down list. There are four selections:
• Default (sym.case 1)
• Symmetry (case 1)
• Symmetry (case 2)
• Not enforced
Pairs of Sealing 
Strips
Number of pairs of sealing strips.
Specification Description
Pass Partition 
Layout
You can select the type of pass partition from the drop-
down list. There are four selections:
• Not set
• H Banded
• Double Banded
• Ribbon Banded
Vertical PP Lane 
Width
Vertical pass partition lane width.
Horizontal PP 
Lane Width
Horizontal pass partition lane width.
Specification Description
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-145
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ThTubes Configuration
If you select the Tubes radio button in the Bundle Data group, 
the Bundle page appears as shown in the figure below:
The configuration information you can specify for the tubes is 
sorted into two groups:
• Tube Characteristics 
• Lengths Along Tube
Tube Characteristics Group
The Tube Characteristics group allows you to specify the 
configuration for the tube.
 Figure 4.78
Specification Description
Tube Type You can select the type of tube you want from the 
drop-down lists:
• Default (Plain)
• Plain Tubes
• Lowfin Tubes
• Longitudinal Tubes
Tube Outside 
Diameter
Outside diameter of the tube.
Tube Wall 
Thickness
Thickness of the tube’s wall.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-146
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ThLengths Along Tube Group
The Lengths Along Tube group allows you to specify the lengths 
of each tube section.
Tube Pitch The tube’s pitch.
Tube Pattern 
(Angle)
You can select the pattern of the tube from the drop-
down list:
• Default (Triangular)
• Triangular (30 deg)
• Rotated square (45)
• Roated triang. (60)
• Square (90 deg)
Specification Description
Tube Length Length of the tube.
Endlength (Front 
Head)
Length of the front head of the tube.
Endlength (Rear 
Head)
Length of the rear head of the tube.
Tube Outstand 
(Inlet)
The distance the tube inlet end protrudes beyond the 
face of a tube sheet.
Tube Outstand 
(Other)
The distance the tube rear end protrudes beyond the 
face of a tube sheet.
Central Entry/
Exit Length
The distance between the centres of the Flow Baffles 
on either side of a central inlet or outlet nozzle.
HYSYS assumes the two baffle spacings are equal if no 
value is entered.
Dist. After Blank 
Baffle
The distance between the tube and the blank baffle.
H-Shell Central 
Length
Length of the central region in an H-shell. This value is 
the distance between two halves of the axial baffle in 
an H-shell.
HYSYS assumes the value to be double the mean 
length of the end spaces at the ends of the exchanger 
if no value is entered.
Specification Description4-147
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ThBaffles Configuration
If you select the Baffles radio button in the Bundle Data group, 
the Bundle page appears as shown in the figure below:
The configuration information you can specify for the baffles is 
sorted into two groups:
• Baffles
• Intermediate Supports
Baffles Group
The Baffles group allows you to specify the configuration of the 
baffles.
 Figure 4.79
Specification Description
Number of 
Baffles
Number of baffles.
Baffle Type Select the baffle type from the drop-down list:
• Default (Sing.Seg.)
• Single Segmental
• Double Segmental
• Unbar/Low pr.drop
• Rodbaffled
Baffle Pitch The value of the baffle pitch. The baffle pitch is the 
baffle spacing plus the baffle thickness.
Baffle Thickness The baffle thickness.
Baffle Cut The percentage of baffle cut.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-148
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ThIntermediate Support Group
The Intermediate Support group allows you to specify the tube 
supports, other than flow baffles, that help remove the risk of 
vibration damage.
Nozzles Page
The Nozzles page allows you to specify the nozzles in the 
shellside and tubeside. The radio buttons in the Side Data group 
controls which side appears on the page.
Inner Cut 
(Double Seg)
The percentage of inner cut. This is only applicable to 
Double Segmental baffle type.
Baffle Cut 
Orientation
Select the orientation of the baffle cut using the drop-
down list:
• Default (horizontal)
• Vertical
• Horizontal
Diam. Clearance 
- Tube
Diametral clearance between the tube and the baffle 
hole. For a zero clearance, enter 0.
Diam. Clearance 
- Shell
Diametral clearance between the baffles and the shell 
wall. For a zero clearance, enter 0.
Specification Description
Intermediate 
Supports (Inlet)
Number of intermediate supports in the inlet 
endspace. This endspace corresponds to the inlet 
endlength.
Intermediate 
Supports/Baffle
Number of intermediate supports between each 
pair of flow baffles.
Intermediate 
Supports (Return)
Number of intermediate supports in the endspace 
corresponding to the outlet (return) endlength.
U-bend Extra 
Supports
Number of tube supports on the U-bend.
Int. Supports 
(Central Nozzle)
Number of intermediate supports for nozzles (not 
over inlet or return endspace).
Support/Blanking 
Baffle
Select whether there is a support of blanking baffle 
at the rear end head:
• Default (Yes for S T)
• Yes
• No
Longitudinal Baffle 
Leakage
An estimate of the percentage of the shellside flow 
which leaks across the longitudinal baffle. This 
value is only relevant to the F, G, or H shell types.
Specification Description
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-149
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4-150 Heat Exchanger
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ThShellside Configuration
If you select the Shellside radio button in the Size group, the 
Nozzles page appears as shown in the figure below:
The following table lists and describes the configuration 
information that you can specify for the nozzles in shellside.
 Figure 4.80
Specification Description
Vapour Belt Diam 
Clearance
Diametral annular clearance (difference in 
diameters) between the outside of the shell and 
the vapour belt.
Vapour Belt Slot Area The total flow area of all the slots leading through 
the shell wall (from the vapour belt into the shell).
Vapour Belt Axial 
Length
The axial length of the exchanger occupied by (the 
inside of) the belt.
Impingement Plate 
Thickness
The thickness of the impingement plate.
Nozzle Function You can specify up to three types of nozzle 
function. Select the nozzle function from the drop-
down list:
• Unset
• Inlet
• Outlet
• Intermediate
• Liquid Outlet
• Vapour Outlet
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-150
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ThTubeside Configuration
If you select the Tubeside radio button in the Size group, the 
Nozzles page appears as shown in the figure below:
Nozzle Type Select the nozzle types from the drop-down list:
• Default (Plain)
• Plain
• Plain + Imp Plate
• Vapour Belt
Nozzle Inside 
Diameter
The inside diameter of the nozzle.
Number In Parallel Number of nozzles in parallel on one shell.
Nozzle Orientation Select the nozzle orientation from the drop-down 
list:
• Default
• Top of Shell
• RHSide of Shell
• Bottom of Shell
• LHSide of Shell
Distance to Nozzle The axial distance along the shell to the nozzle 
centre line, measured from the inner surface of 
the tubesheet at the front (fixed) head.
Nozzle Wall 
Thickness
The wall thickness of the nozzle.
 Figure 4.81
Specification Description4-151
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4-152 Heat Exchanger
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ThThe configuration information you can specify for the nozzles in 
tubeside is described in the table below:
Enhanced Surface Page
The Enhanced Surface page allows you to perform model 
calculations on the exchanger that are not explicitly modeled by 
TASC. There are two enhanced options on the page, and you can 
select which enhanced option you want using the radio buttons 
in the Enhanced Surface Data group.
Specification Description
Nozzle Function You can specify up to three types of nozzle function. 
Select the nozzle function from the drop-down list:
• Unset
• Inlet
• Outlet
• Intermediate
• Liquid Outlet
• Vapour Outlet
Nozzle Inside 
Diameter
The inside diameter of the nozzle.
Nozzle 
Orientation
Select the nozzle orientation from the drop-down list:
• Default
• Top of Shell
• RHSide of Shell
• Bottom of Shell
• LHSide of Shell
Vel Head Lost/
FFE Inlet
Number of velocity heads lost in a device (used to 
achieve uniform flow distribution of the liquid in-flow to 
all the tubes of a falling film evaporator).
Nozzle Wall 
Thickness
The wall thickness of the nozzle.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-152
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Heat Transfer Operations 4-153
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ThSpecific Enhanced Option
If you select the Specific Enhanced radio button in the Enhanced 
Surface Data group, the Enhanced Surface page appears as 
shown in the figure below.
The variables you can specify for the Specific Enhanced option 
are sorted into three groups:
• Longitudinal Fins
• Lowfin Tubes
• Tube Inserts
Longitudinal Fins Group
The Longitudinal Fins group allows you to specify the 
configuration of the longitudinal fins.
 Figure 4.82
Specification Description
Fins Per Tube Number of fins are on each tube.
Fin Height Height of each fin.
Fin Thickness Thickness of each fin.
Fin Root Spacing The root spacing of each fin.
Cut and Twist Length The cut and twist length.4-153
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4-154 Heat Exchanger
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ThLowfin Tubes Group
The Lowfin Tubes group allows you to specify the configuration 
of the lowfin tubes.
Tube Inserts Group
The Tube Inserts group allows you to specify the configuration of 
the tube inserts.
Specification Description
Fin Pitch The lowfin fin pitch.
Fin Height The height of each fin.
Fin Thickness The thickness of each fin.
Root Diameter The lowfin tube root diameter.
Wall Thickness The lowfin tube wall thickness.
Unfinned at Baffle Length of unfinned tubing at a baffle.
Specification Description
Tube Insert Select the type of tube inserts from the drop-down list:
• Default (plain tubes)
• None (plain tubes)
• Twisted tape
Twisted Tape 
Thickness
The twisted tape thickness. The value only applies if 
you selected twisted tape for the tube insert.
360 Degree 
Twisted Pitch
The distance between each 360 degree twist of a 
twisted tape insert.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-154
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ThSpecific Enhanced Option
If you select the General Enhanced radio button in the Enhanced 
Surface Data group, the Enhanced Surface page appears as 
shown in the figure below:
The variables you can specify for the General Enhanced option is 
sorted into two groups:
• Identity of Surface
• Surface Performance
Identity of Surface Group
The Identity of Surface group allows you to create surfaces for 
both the shellside and tubeside.
 Figure 4.83
Specification Description
Add Surface Allows you to add/create a surface. 
Remove Surface Allows you to remove the last surface.
Name of 
Enhanced 
Surface
Contains the name of the surface created. HYSYS 
automatically names the surface as “Set” followed by a 
number. The number value is incremented by 1 for 
each new surface created.
Shellside or 
Tubeside
Select which side the surface created on from the 
drop-down list:
• Not used
• Shellside
• Tubeside
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-155
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4-156 Heat Exchanger
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ThSurface Performance Group
The Surface Performance group allows you to specify the 
configuration of each surface.
Design and Material Page
The Design and Material page allows you to specify design 
values, material types, and some properties for the Heat 
Exchanger. The information on this page is sorted into three 
groups:
• Design Data
• Materials
• User Defined Properties
Specification Description
Surface Contains the list of surfaces created. 
Any values entered in the table located at the right of the 
list apply only to the surface you selected in the list.
Re The Reynolds Number for the corresponding surface.
f The friction factor for the corresponding surface.
Cj The heat transfer factor (Colburn j factor) for the 
corresponding surface.
 Figure 4.844-156
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ThDesign Data Group
The Design Data group allows you to specify the following 
variables:
Materials Group
The Materials group allows you to select the material type for 
the heat exchanger. HYSYS lets you select the material for four 
parts of the heat exchanger: Tubes, Shell, Tubeplate, and 
Channel. You can select the material type from the drop-down 
list provided for each part. 
Specification Description
Shellside Design 
Temperature
Design temperature on the shellside.
Shellside Design 
Pressure
Design pressure on the shellside.
Tubeside Design 
Temperature
Design temperature on the tubeside.
Tubeside Design 
Pressure
Design pressure on the tubeside.
TEMA Class Select the TEMA class from the drop-down list:
• Default (R)
• R
• C
• B
• Not TEMA
Crossflow Fraction 
for Vibration
The fraction from the shellside flow in the cross 
flow which causes vibration.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-157
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ThUser Defined Properties Group
The User Defined Properties group allows you to specify values 
for the following properties:
Methods Page
The Methods page allows you to specify the process methods 
and constraints of the heat exchanger. The Methods and 
Constraints group contains three radio buttons:
• Process Methods
• Process Constraints
• Other
The variables displayed on this page depend on the radio button 
you selected in the Methods and Constraints group.
Specification Description
Thermal 
Conductivity
The thermal conductivity of the tube material. This value 
overrides the calculated value based on the tube material 
selected.
Density Density for all the exchanger materials. This value 
overrides the calculated value based on the selected 
materials for each part of the exchanger.
Youngs 
Modulus
The Young’s Modulus. This value overrides the calculated 
value based on the tube material selected.4-158
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ThProcess Methods Variables
If you select the Process Methods radio button from the Methods 
and Constraints group, the Methods page appears as shown in 
the figure below: 
The table below lists the variables available for the process 
method:
 Figure 4.85
Method Description
Vapour Shear 
Enhancement
Select whether the process stream has vapour shear 
enhancement from the drop-down list:
• Default (Yes)
• Yes
• No
Wet Wall 
Desuperheating
Select whether the process stream has wet wall 
desuperheating from the drop-down list:
• Default (Yes)
• Yes
• No
Number of Points 
on Curve
Specify the number of points on the TASC stream heat 
load curve in this field. The minimum value is 6 and 
the maximum value is 12.
Fit to Property 
Curve
Select whether the results fit the property curve from 
the drop-down list:
• Default
• A input / calc.
• Use best fit
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-159
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ThSubcooled 
Boiling
Select whether there is subcooled boiling from the 
drop-down list:
• Default(ht.tr&pr.drop)
• Allow in heat.tr&pr.drop
• Allow in heat tran. only
• Allow in press. drop only
• Not allowed for
Post Dryout Heat 
Transfer
Select whether there is post dryout heat transfer from 
the drop-down list:
• Default (allow)
• Allow for
• Assume Boiling
Pressure Drop 
Calculations
Select the type of pressure drop calculations from the 
drop-down list:
• Default (fric+acc)
• Frict+Acc+Gravitation
• Friction+Accel
HTFS Colburn-
Hougen Method
Select whether to apply HTFS Colburn-Hougen method 
from the drop-down list:
• Default (no)
• Yes
• No
Downflow 
Condensate 
Cooling
Select the type of downflow condensate cooling from 
the drop-down list:
• Default (standard)
• Falling Film
• Standard Method
Method Description4-160
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ThProcess Constraints Variables
If you select the Process Constraints radio button from the 
Methods and Constraints group, the Methods page appears as 
shown in the figure below: 
The table below contains a list of the constraints available in the 
operation:
 Figure 4.86
Constraints Description
Revise for Heat Balance Select the type of revise for heat balance from 
the drop-down list:
• Default (h.load)
• Heat Load
• Outlet Temp.
• Inlet Temp.
• Flowrate
Liquid Heat Transfer 
Coefficient
Amount of liquid heat transfer coefficient.
Two Phase Heat Transfer 
Coefficient
Amount of two phase heat transfer coefficient.
Vapour Heat Transfer 
Coefficient
Amount of vapour heat transfer coefficient.
Liquid Heat Transfer 
Coefficient Multiplier
The liquid heat transfer coefficient multiplier.
Two Phase Heat Transfer 
Coefficient Multiplier
The two phase heat transfer coefficient 
multiplier.
Vapour Heat Transfer 
Coefficient Multiplier
The vapour heat transfer coefficient multiplier.
Pressure Drop Multiplier The pressure drop multiplier.
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-161
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ThOther Variables
If you select the Other radio button from the Methods and 
Constraints group, the Methods page appears as shown in the 
figure below. 
The table below contains a list of variables available in the 
operation.
Results Page
The Heat Exchanger results appear on this page. The results are 
created in a text format that can be exported to HTFS-TASC.
 Figure 4.87
Variables Description
Units of 
Output
Select the type of unit for the output from the drop-down 
list:
• Default (as Input)
• SI
• British/US
• Metric
• unused option
Physical 
Property 
Package
Select the type of physical property package from the drop-
down list:
• Default (Sep.File)
• In Lineprinter O/p
• Separate File
• No Output
Tube Layout 
Data
Select the type of tube layout data from the drop-down list:
• Default (use if available)
• Use if available
• Revise from input
• Ignore layout data
Refer to the TASC 
Thermal Reference 
guide for information 
about the selections 
available.4-162
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Th4.5 LNG
The LNG (Liquefied Natural Gas) exchanger model solves heat 
and material balances for multi-stream heat exchangers and 
heat exchanger networks. The solution method can handle a 
wide variety of specified and unknown variables.
For the overall exchanger, you can specify various parameters, 
including heat leak/heat loss, UA or temperature approaches. 
Two solution approaches are employed; in the case of a single 
unknown, the solution is calculated directly from an energy 
balance. In the case of multiple unknowns, an iterative approach 
is used that attempts to determine the solution that satisfies not 
only the energy balance, but also any constraints, such as 
temperature approach or UA.   
The dynamic LNG exchanger model performs energy and 
material balances for a rating plate-fin type heat exchanger 
model. The dynamic LNG is characterized as having a high area 
density, typically allowing heat exchange even when low 
temperature gradients and heat transfer coefficients exist 
between layers in the LNG operation.
Some of the major features in the dynamic LNG operation 
include:
• A pressure-flow specification option which realistically 
models flow through the LNG operation according to the 
pressure network of the plant. Possible flow reversal 
situations can therefore be modeled.
• A dynamic model, which accounts for energy holdup in 
the metal walls and material stream layers. Heat transfer 
between layers depends on the arrangement of streams, 
metal properties, and fin and bypass efficiencies.
• Versatile connections between layers in a single or 
multiple zone LNG operation. It is possible to model cross 
and counter flow, and multipass flow configurations 
within the LNG operation.
The LNG allows for multiple streams, while the heat 
exchanger allows only one hot side stream and one cold side 
stream.4-163
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Th• A heat loss model, which accounts for the convective and 
conductive heat transfer that occurs across the wall of 
the LNG operation.
4.5.1 Theory
Heat Transfer
The LNG calculations are based on energy balances for the hot 
and cold fluids. The following general relation applies any layer 
in the LNG unit operation.
where:  
M = fluid flow rate in the layer
 = density
H = enthalpy
Qinternal = heat gained from the surrounding layers
Qexternal = heat gained from the external surroundings
V = volume shell or tube holdup
LNG dynamics constructs and builds the conductive heat 
transfer equations into the dynamic solvers to account for the 
metal thermal inertia for both plates and fins.
(4.37)
(4.38)
(4.39)
M Hin Hout–( ) Qinternal Qexternal+ + ρ
d VHout( )
dt
----------------------=
ρ
Mw Cpw×
dTw
dt
---------× Qin Qout–( )=
Qcond
k
x
-- A× Tw1 Tw2–( )=4-164
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Thwhere:  
Mw = wall mass
Cpw = wall heat capacity
Tw = average wall temperature
t = time
Qin/Qout = the heat transfer to/from the wall
Qcond = conductive heat transfer
k = metal thermal conductivity 
x = wall thickness
A = heat transfer area
Tw1 and Tw2 = temperature of the two sides of the wall
Pressure Drop
The pressure drop across any layer in the LNG unit operation 
can be determined in one of two ways:
• Specify the pressure drop.
• Define a pressure flow relation for each layer by 
specifying a k-value.
If the pressure flow option is chosen for pressure drop 
determination in the LNG, a k value is used to relate the 
frictional pressure loss and flow through the exchanger. 
This relation is similar to the general valve equation:
This general flow equation uses the pressure drop across the 
heat exchanger without any static head contributions. The 
quantity, P1 - P2, is defined as the frictional pressure loss which 
is used to “size” the LNG with a k-value.
(4.40)f density k× P1 P2–=4-165
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ThConvective (U) & Overall (UA) Heat 
Transfer Coefficients
It is important to understand the differences between steady 
state and dynamics LNG models. The Steady State model is 
based on heat balances, and a number of specifications related 
to temperatures and enthalpy. In this model, the UA values are 
calculated based on heat curves. Whereas, the dynamic LNG 
model is a rating model, which means the outlet streams are 
determined by the physical layout of the exchanger.
In steady state the order of the streams given to the LNG is not 
important but in the dynamics rating model the ordering of 
streams inside layers in each zone is an important 
consideration. The U value on the dynamics page of LNG refers 
to the convective heat transfer coefficient for that stream in 
contact with the metal layer.
For convenience, you can also specify a UA value in Dynamic 
mode for each layer, and it is important to note that this value is 
not an overall UA value as it is in steady state but accounts 
merely for the convective heat transfer of the particular stream 
in question with its immediate surroundings. These UA values 
are thus not calculated in the same way as in Steady State 
mode.
In Dynamic mode the U and UA value refers to the convective 
heat transfer (only) contribution between a stream and the 
metal that immediately surrounds it. The overall duty of each 
stream, in dynamic mode, is influenced by the presence of metal 
fins, fin efficiencies, direct heat flow between metal layers, and 
Several of the pages in the LNG property view indicate 
whether the information applies to steady state or dynamics.4-166
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Thother factors, as it would be in a real plate-fin exchanger.
Ideally in Dynamic mode the convective heat transfer 
coefficient, U, for each stream is specified. An initial value can 
be estimated from correlations commonly available in the 
literature or from the steady state UA values. The values 
specified can be manipulated by a spread sheet if desired. If the 
shut down and start up of the LNG is to be modeled, then the U 
flow scaled calculator should be selected on the Heat Transfer 
page, of the Rating tab, as it correctly scales the U values based 
on the flow.
If the streams in the rating model are properly laid to optimize 
heat transfer (in other words, arranged in the fashion hot-cold-
hot-cold and not hot-hot-cold-cold on the Model page of the 
Dynamics tab), and the metal resistance is not significant and 
significant phase change is not taking place, then the UA values 
reported by steady state approximates the convective UA values 
that can be specified in Dynamic mode for the same results.
If you specify the convective UA values in Dynamic mode, 
than the size and metal holdup of the LNG are still 
considered.4-167
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ThDynamic Specifications
The following table lists the minimum dynamic specifications 
required for the LNG unit operation to solve:
4.5.2 LNG Property View
There are two ways to add a LNG Exchanger to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12 .
2. Click the Heat Transfer Equipment radio button.
3. From the list of available unit operations, select LNG.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the LNG icon. 
Specification Description
Zone Sizing The dimensions of each zone in the LNG operation must be 
specified. All information in the Sizing page of the Rating 
tab must be completed. You can modify the number of 
zones in the Model page of the Dynamics tab.
Layer Rating The individual layer rating parameters for each zone must 
be specified. All information on the Layers page of the 
Rating tab must be completed.
Heat 
Transfer
Specify an Overall Heat Transfer Coefficient, U, or Overall 
UA.
These specifications can be made on the Heat Transfer page 
of the Rating tab.
Pressure 
Drop
Either specify an Overall Delta P or an Overall K-value for 
the LNG.
Specify the Pressure Drop calculation method on the Specs 
page of the Dynamics tab.
Layer 
Connections
Every layer in each zone must be specified with one feed 
and one product. Complete the Connections group for each 
zone on the Model page of the Dynamics tab.
LNG icon4-168
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ThThe LNG property view appears.
To ignore the LNG during calculations, select the Ignored 
checkbox. HYSYS completely disregards the operation (and 
cannot calculate the outlet stream) until you restore it to an 
active state by clearing the checkbox.
4.5.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Specs
• User Variables
• Notes
 Figure 4.884-169
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ThConnections Page
The Connections page is shown in the figure below.
For each exchanger side:
• An inlet stream and outlet stream are required.
• A Pressure Drop is required.
• The Hot/Cold designation can be specified. This is used 
as an estimate for calculations and is also used for 
drawing the PFD. If a designated hot pass is actually cold 
(or vice versa), the operation still solves properly. The 
actual Hot/Cold designation (as determined by the LNG) 
can be found on the Side Results page.
• The main flowsheet is the default shown in the flowsheet 
column.
The LNG status appears on the bottom of the property view, 
regardless of which page is currently shown. It displays an 
appropriate message such as Under Specified, Not Converged, 
or OK.
 Figure 4.89
Any number of Sides can be added simply by clicking the Add 
Side button. To remove a side, select the side to be deleted 
and click the Delete Side button.4-170
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ThParameters Page
On the Parameters page, you have access to the exchanger 
parameters, heat leak/loss options, the exchanger details, and 
the solving behaviour.
Exchanger Parameters Group
In Steady State mode, you can select either an End Point or 
Weighted Rating Method.
 Figure 4.90
Parameters Description
Rating 
Method
For the Weighted method, the heating curves are broken 
into intervals, which then exchange energy individually. An 
LMTD and UA are calculated for each interval in the heat 
curve and summed to calculate the overall exchanger UA.
Shell Passes You have the option of having HYSYS perform the 
calculations for Counter Current (ideal with Ft = 1.0) 
operation or for a specified number of shell passes. You can 
specify the number of shell passes to be any integer 
between 1 and 7.
If there are more than two LNG sides, then only the 
Weighted rating method can be used.4-171
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ThHeat Leak/Loss Group
By default, the None radio button is selected. The other two 
radio buttons incorporate heat loss/heat leak: 
Exchange Details Group
The LNG Exchange Details appear as follows:
For each side, the following parameters can be specified:
Radio Button Description
Extremes The heat loss and heat leak are considered to occur only at 
the end points (inlets and outlets) and are applied to the 
Hot and Cold Equilibrium streams.
Proportional The heat loss and heat leak are applied over each interval.
Heat Leak/Loss group is available only when the Rating 
Method is Weighted.
 Figure 4.91
Parameter Description
Intervals The number of intervals, applicable only to the Weighted 
Rating Method, can be specified. For non-linear 
temperature profiles, more intervals are necessary.
Dew/Bubble 
Point
Select this checkbox to add a point to the Heat curve for a 
phase change. Figure 4.92 illustrates the effect of the 
number of intervals and inclusion of the dew and bubble 
points on the temperature / heat flow curves. Temperature 
is on the y-axis, and heat flow is on the x-axis
Equilibrate All sides that are checked comes to thermal equilibrium 
before entering into the UA and LMTD calculations. If only 
one hot stream or cold stream is checked, then that stream 
is by definition in equilibrium with itself and the results are 
not affected. If two or more hot or cold streams are 
checked, then the effective driving force is reduced. All 
unchecked streams enter the composite curve at their 
respective temperatures.4-172
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ThStep Type There are three choices, which are described below.
• Equal Enthalpy. All intervals have an equal enthalpy 
change.
• Equal Temperature. All intervals have an equal 
temperature change.
• Auto Interval. HYSYS determines where points 
should be added to the heat curve. This is designed to 
minimize the error, using the least amount of 
intervals.
Pressure 
Profile
The Pressure Profile is updated in the outer iteration loop, 
using one of the following methods described below.
• Constant dPdH. Maintains constant dPdH during 
update.
• Constant dPdUA. Maintains constant dPdUA during 
update.
• Constant dPdA. Maintains constant dPdA during 
update. This is not currently applicable to the LNG 
Exchanger in steady state, as the area is not 
predicted.
• Inlet Pressure. The pressure is constant and equal to 
the inlet pressure.
• Outlet Pressure. The pressure is constant and equal 
to the pressure.
Parameter Description
 Figure 4.92
10 Intervals; Dew Bubble Points 
included
3 Intervals; Dew Bubble Points not 
included4-173
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ThSpecs Page
On the Specs page, there are three groups which organize the 
various specification and solver information.
Solver Group
The Solver group includes the solving parameters used for 
LNG’s:
 Figure 4.93
Solver 
Parameter
Specification Description 
Tolerance You can set the calculation error tolerance.
Current Error When the current error is less than the calculation 
tolerance, the solution is considered to have converged.
Maximum 
Iterations
You can specify the maximum number of iteration before 
HYSYS stops the calculations.
Iteration The current iteration of the outer loop appears. In the outer 
loop, the heat curve is updated and the property package 
calculations are performed. Non-rigorous property 
calculations are performed in the inner loop. Any 
constraints are also considered in the inner loop.
Unknown 
Variables
Displays the number of unknown variables in the LNG.4-174
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ThUnknown Variables Group
HYSYS lists all unknown LNG variables according to your 
specifications. Once the unit has solved, the values of these 
variables appear.
Specifications Group
Notice the Heat Balance (specified at 0 kJ/h) is considered to 
be a constraint. This is a Duty Error spec; if you turn it off, the 
heat equation cannot balance. Without the Heat Balance spec, 
you can, for example, completely specify all four heat exchanger 
streams, and have HYSYS calculate the Heat Balance error, 
which would be displayed in the Current Value column of the 
Specifications group.
You can view or delete selected specifications by using the 
buttons that align the right of the group. A specification property 
view appears automatically each time a new spec is created via 
the Add button. 
Constraints Displays the number specifications you have placed on the 
LNG.
Degrees of 
Freedom
Displays the number of Degrees of Freedom on the LNG.
To help reach the desired solution, unknown parameters 
(flows, temperatures) can be manipulated in the attached 
streams. Each parameter specification reduces the Degrees 
of Freedom by one.
The number of Constraints (specs) must equal the number 
of Unknown Variables. When this is the case, the Degrees 
of Freedom is equal to zero, and a solution is calculated.
The Heat Balance specification is a default LNG specification 
that must be active for the heat equation to balance.
Solver 
Parameter
Specification Description 4-175
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ThIn the figure below is a typical property view of a specification, 
which is accessed via the View or Add button.
Each specification property view has two tabs:
• Parameters
• Summary
The Summary page is used to define whether the specification is 
Active or an Estimate. The Spec Value is also shown on this 
page.    
 Figure 4.94
Information specified on the Summary page of the 
specification property view also appears in the Specifications 
group.
As an example, 
defining the Delta 
Temp Spec 
requires two 
stream names, 
and a value for 
the specification.4-176
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ThAll specifications are one of the following three types:
The specification list allows you to try different combinations of 
the above three specification types. For example, suppose you 
have a number of specifications, and you want to determine 
which ones should be active, which should be estimates and 
which ones should be ignored altogether. By manipulating the 
checkboxes among various specifications, you can test various 
combinations of the three types to see their effect on the 
results.
The available specification types are:
Specification 
Type
Action
Active An active specification is one which the convergence 
algorithm is trying to meet. Notice an active specification 
always serves as an initial estimate (when the Active 
checkbox is selected, HYSYS automatically selects the 
Estimate checkbox). An active specification exhausts one 
degree of freedom.
An Active specification is one which the convergence 
algorithm is trying to meet. Both checkboxes are selected 
for this specification.
Estimate An estimate is considered an Inactive specification because 
the convergence algorithm is not trying to satisfy it. To use 
a specification as an estimate only, clear the Active 
checkbox. The value then serves only as an initial estimate 
for the convergence algorithm. An estimate does not use an 
available degree of freedom.
An Estimate is used as an “initial guess” for the 
convergence algorithm, and is considered to be an Inactive 
specification.
Completely 
Inactive
To disregard the value of a specification entirely during 
convergence, clear both the Active and Estimate 
checkboxes. By ignoring rather than deleting a 
specification, it is available if you want to use it later or 
simply view its current value.
A Completely Inactive specification is one which is ignored 
completely by the convergence algorithm, but can be made 
Active or an Estimate at a later time.
Specification Description
Temperature The temperature of any stream attached to the LNG. The 
hot or cold inlet equilibrium temperature can also be 
defined.
Delta Temp The temperature difference at the inlet or outlet between 
any two streams attached to the LNG. The hot or cold inlet 
equilibrium temperatures can also be used.4-177
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Minimum 
Approach
The minimum temperature difference between the specified 
pass and the opposite composite curve. For example, if you 
select a cold pass, this is the minimum temperature 
difference between that cold pass and the hot composite 
curve.
• The Hot Inlet Equilibrium temperature is the 
temperature of the inlet hot stream minus the heat 
loss temperature drop. 
• The Cold Inlet Equilibrium temperature is the 
temperature of the inlet cold stream plus the heat leak 
temperature rise.
UA The overall UA (product of overall heat transfer coefficient 
and heat transfer area).
LMTD The overall log mean temperature difference. It is 
calculated in terms of the temperature approaches 
(terminal temperature differences) in the exchanger. See 
Equation (4.41).
Duty The overall duty, duty error, heat leak or heat loss. The 
duty error should normally be specified as 0 so that the 
heat balance is satisfied. The heat leak and heat loss are 
available as specifications only if Heat Loss/Leak is set to 
Extremes or Proportional on the Parameters page.
Duty Ratio A duty ratio can be specified between any two of the 
following duties: overall, error, heat loss, heat leak or any 
pass duty.
Flow The flowrate of any attached stream (molar, mass or liquid 
volume).
Flow Ratio The ratio of any two inlet stream flowrates.
Specification Description
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.4-178
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Th4.5.4 Rating Tab
The Rating tab contains the following pages:
• Sizing (dynamics)
• Layers (dynamics)
• Heat Transfer (dynamics)
Sizing (dynamics) Page
On the Sizing (dynamics) page, you can specify the geometry of 
each zone in the LNG unit operation.
You can partition the exchanger into a number of zones along its 
length. Each zone features a stacking pattern with one feed and 
one product connected to each representative layer in the 
pattern.
In practice, a plate-fin heat exchanger may have a repeating 
pattern of layers in a single exchanger block. A set is defined as 
a single pattern of layers that are repeated over the height of an 
While working exclusively in Steady State mode, you are not 
required to change any information on the pages accessible 
through this tab.
 Figure 4.954-179
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Thexchanger block. Each zone can be characterized with a multiple 
number of sets each with the same repeating pattern of layers.
The figure below displays an LNG exchanger block (zone) with 3 
sets, each containing 3 layers:
The Zone Sizing and Configuration group contains information 
regarding the geometry, heat transfer properties, and 
configuration of each zone in the LNG unit operation. To edit a 
zone, select the individual zone in Zone group, and make the 
necessary changes to the other groups.
The Zone Geometry group displays the following information 
regarding the dimensions of each zone:
• Width
• Length
This length refers to the actual length of the exchanger, which is 
used for heat transfer. The remainder is taken up by the flow 
distributors. The flow of material travels in the direction of the 
 Figure 4.964-180
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Thlength of the exchanger block. The fins within each layer are 
situated across the width of the exchanger block.
The Zone Metal Properties group contains information regarding 
the metal heat transfer properties:
• Thermal Conductivity
• Specific Heat Capacity, Cp
• Density
The Zone Layers group contains the following information 
regarding the configuration of layers in the zone:
• Number of Layers in a Set
• Repeated Sets
Layers (dynamic) Page
The Layers (dynamics) page contains information regarding the 
plate and fin geometry:
 Figure 4.97
The Copy First Layer Properties to All button can be clicked if you 
want to specify all the layers in the zone with the same plate and fin 
properties.4-181
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ThEach of the following plate and fin properties should be specified 
for every layer in each zone if the LNG operation is to solve:
Heat Transfer (dynamics) Page
The Heat Transfer (dynamics) page displays the heat transfer 
coefficients associated with the individual layers of the LNG unit 
operation. You can select internal or external heat transfer by 
selecting the appropriate Heat Transfer radio button.
HYSYS accounts for the heating and cooling of the metal fins 
and plates in the LNG unit operation. The calculation of heat 
accumulation in the metal is based on the conductive heat 
transfer properties, fin efficiencies, and various other correction 
factors. An initial metal temperature can be specified for each 
zone in the Initial Metal Temperature field.
Since a repeating stacking pattern is used, the top most layer of 
a set is assumed to exchange heat with the bottom layer of the 
set above.
You can also select the Brazed Aluminum Plate-Fin heat transfer 
calculation standards by selecting the Calculate fin area using 
the standards of the Brazed Aluminium Plate-Fin HX 
Manufacturer’s Association checkbox.
Select the Auto Prevent Temp. Cross checkbox to enter two 
parameters for split steps, and prevent the temperature from 
crossing along the heat transfer passes.
Plate and Fin 
Property
Description
Fin Perforation The perforation percentage represents the area of 
perforation relative to the total fin area. Increasing the 
Fin Perforation decreases the heat transfer area.
Height The height of the individual layers. This affects the 
volume of each layer holdup.
Pitch The pitch is defined as the fin density of each layer. The 
pitch can be defined as the number of fins per unit 
width of layer.
Fin thickness The thickness of the fin in the layer.
Plate thickness The thickness of the plate.4-182
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ThSelect the Automatically Update k’s checkbox to 
automatically update the k’s based on current relationships 
between P-F flow rates and pressure drops for all the heat 
transfer layers, making the LNG steam flow rates more stable. 
LNG Temperature Crossing Project
The LNG Temperature Crossing Project redistributes the zone 
length fractions among the total flow pass length and multiple 
zones to prevent the temperature from crossing along the heat 
transfer passes. 
It uses a cascade of lumping heat zones to incorporate the 
distributed systems, and requires at least 10 zones to 
automatically remove the big temperature wiggle profiles within 
the flow passes. Under certain conditions, such as zone number 
and the changes in temperature and flow rates, the original 
function of Auto Prevent Temp Cross could smooth the small 
temperature waves. But it also made the dynamic processes 
unstable. 
To minimize temperature and flow instability in the LNG dynamic 
processes:
1. Specify 10 or more heat zones to remove the wiggle temperature 
profiles.
2. Select the Automatically Update k’s checkbox to make the 
LNG flow rates more stable if your LNG flow rates are not too 
small.
3. Select the Auto Prevent Temp Cross checkbox to prevent 
temperature cross and lessen small temperature waves .
4. Use the following parameters for the Auto Prevent Temperature 
Crossing:
• Reach small split steps 
- A smaller value (0.001-1000) helps to prevent small 
temperature crossing.
• Reach even split steps
- A small value (0.1-1000) leads to a quick speed.
 Figure 4.984-183
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ThInternal Heat Transfer
If you select the Internal radio button, the internal heat transfer 
coefficient associated with each layer appears as shown in the 
figure below.
Currently, the internal heat transfer coefficient, U, or the overall 
UA must be specified for the LNG unit operation. HYSYS cannot 
calculate the heat transfer coefficient from the geometry/
configuration of the plates and fins. The Internal Heat Transfer 
group contains the following parameters:
 Figure 4.99
Parameter Description
U Calculator The heat transfer calculator currently available in 
HYSYS are U specified and U flow scaled. If U specified 
is selected, you must specify the internal heat transfer 
coefficient, U. Alternatively, you can select U flow 
scaled calculator and a reference flow rate is used to 
calculate U. If you are modeling a shut-down or a 
start-up LNG process, select U flow scaled calculator to 
correctly scale the U values based on the flow 
condition.
U The internal heat transfer coefficient is specified in this 
cell.
Ref. Flow The Reference Flow is used to calculate U when the U 
Flow Scaled calculator is selected.
Min Scale The minimum scale factor is applied to U by the U Flow 
Scaled calculator when the flow changes.4-184
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ThExternal Heat Transfer
If you select the External radio button, the overall UA associated 
with heat loss to the atmosphere appears.
Like the internal heat transfer coefficients, the external overall 
UA must be specified.The External Heat Transfer group contains 
the following parameters:
Override UA The overall UA can be specified if the Override UA 
checkbox is selected. The specified UA value is used 
without the consideration or back calculation of the 
internal heat transfer coefficient, U. 
Convective UA The overall UA is specified in this cell.
 Figure 4.100
Parameter Description
External T The ambient temperature surrounding the plate-fin heat 
exchanger. This parameter may be specified or can remain 
at its default value.
UA The overall UA is specified in this field. The heat gained 
from the ambient conditions is calculated using the overall 
UA.
Parameter Description4-185
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Th4.5.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the LNG unit operation. 
4.5.6 Performance Tab
The Performance tab contains detail performance results of the 
LNG exchanger. The calculated results are displayed in the 
following pages:
• Results (SS). Contains information relevant only to 
Steady State mode.
• Plots (SS/Dyn). Contains information relevant to both 
Steady State and Dynamics mode.
• Tables (SS). Contains information relevant only to Steady 
State mode.
• Summary (dynamics). Contains information relevant only 
to Dynamics mode.
• Layers (dynamics). Contains information relevant only to 
Dynamics mode.
Q1 Q1 is calculated from the overall UA and the ambient 
temperature. If heat is gained in the holdup, Q1 is positive; 
if heat is lost, Q1 is negative.
Qfixed A fixed heat value can be added to each layer in the LNG 
unit operation. Since Qfixed does not vary, a constant heat 
source or sink is implied (for example, electrical tracing). If 
heat is gained in the holdup, Qfixed is positive; if heat is 
lost, Qfixed is negative.
The PF Specs page is relevant to dynamics cases only.
Parameter Description
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.4-186
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ThResults Page
The Results page displays the calculated values generated by 
HYSYS. These values are split into three groups for your 
convenience. 
Overall Performance Group
 Figure 4.101
Parameter Description
Duty Combined heat flow from the hot streams to the cold 
streams minus the heat loss. Conversely, this is the heat 
flow to the cold streams minus the heat leak.
Heat Leak Loss of cold side duty to leakage.
Heat Loss Loss of hot side duty to leakage.
UA Product of the Overall Heat Transfer Coefficient and the 
Total Area available for heat transfer. The LNG Exchanger 
duty is proportional to the overall log mean temperature 
difference, where UA is the proportionality factor. That is, 
the UA is equal to the overall duty divided by the LMTD.
Minimum 
Approach
The minimum temperature difference between the hot and 
cold composite curves.
LMTD The LMTD is calculated in terms of the temperature 
approaches (terminal temperature differences) in the 
exchanger, using Equation (4.41).4-187
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ThThe equation used to calculate LMTD is:
where:  
Detailed Performance Group
Side Results Group
The Side Results group displays information on each Pass. For 
each side, the inlet and outlet temperatures, molar flow, duty, 
UA, and the hot/cold designation appear.
(4.41)
Parameter Description
Estimated UA 
Curvature Error
The LMTD is ordinarily calculated using constant 
heat capacity. An LMTD can also be calculated 
using linear heat capacity. In either case, a 
different UA is predicted. The UA Curvature Error 
reflects the difference between these UAs.
Hot Pinch 
Temperature
The hot stream temperature at the minimum 
approach between composite curves.
Cold Pinch 
Temperature
The cold stream temperature at the minimum 
approach between composite curves.
Cold Inlet 
Equilibrium 
Temperature
The Equilibrium Temperature for the cold streams. 
When streams are not equilibrated (see the 
Parameters page), the Equilibrium temperature is 
the coldest temperature of all cold inlet streams.
Hot Inlet Equilibrium 
Temperature 
The Equilibrium Temperature for the hot streams. 
When streams are not equilibrated (see the 
Parameters Page), the Equilibrium temperature is 
the hottest temperature of all hot inlet streams.
ΔTLM
ΔT1 ΔT2–
ΔT1 ΔT2⁄( )ln
---------------------------------=
ΔT1 Thot out, Tcold in,–=
ΔT2 Thot in, Tcold o, ut–=4-188
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ThPlots Page
On the Plots page, you can plot composite curves or individual 
pass curves for the LNG. The options available on this page 
varies, depending on the type of mode (Steady State or 
Dynamics) your simulation case is in. 
Use the checkboxes under the Plot column to select which 
curve(s) you want to appear in the plot. 
• In Steady State mode, all the checkboxes under the 
Plots column are active. 
• In Dynamics mode, the Cold Composite and Hot 
Composite checkboxes are unavailable.
The data displayed in the plot varies depending on the 
simulation mode:
• In Steady State mode, the information in the plot is 
controlled by the selection in the Plot Type drop-down 
list.
 Figure 4.102
You can modify the appearance of the plot via the Graph 
Control property view. 
The Plot Type drop-down list is only available at Steady State 
mode.
Refer to Section 1.3.1 - 
Graph Control Property 
View for more 
information.4-189
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ThThe Plot Type drop-down list enables you to select any 
combination of the following data for the x and y axes: 
Temperature, UA, Delta T, Enthalpy, Pressure, and Heat 
Flow.
• In the Dynamics mode, the plot only displays the 
Temperature vs. Zone data.
Use the View Plot button to open the plot area in a separate 
property view.
Tables Page
On the Table page, you can examine the interval Temperature, 
Pressure, Heat Flow, Enthalpy, UA, Vapour Fraction, and Delta T 
for each side of the Exchanger in a tabular format. Choose the 
side, Cold Composite or Hot Composite, by making a selection 
from the Side drop-down list located above the table.
Summary Page
The Summary page displays the results of the dynamic LNG unit 
operation calculations.
On this page, the following zone properties appear for each 
layer:
• Layer
• Inlet Temperature
 Figure 4.1034-190
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Th• Exit Temperature
• Inlet Enthalpy
• Exit Enthalpy
• Inlet Flow rate
• Outlet Flow rate
• Fluid Duty
• Fluid Volume
• Surface Area
• Metal Mass
The Fluid Duty is defined as the energy specified to the holdup. 
If the fluid duty is positive, the layer gains energy from its 
surroundings; if the fluid duty is negative, the layer loses energy 
to its surroundings.
Layers Page
The Layers page displays information regarding local heat 
transfer and fluid properties at endpoint locations in each layer 
of each zone. 
If the Combine Layers checkbox is selected in the Model 
page of the Dynamics tab, some parameters in the Summary 
page of the Performance tab include contributions from 
multiple layers.
 Figure 4.1044-191
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ThUse the Zone, Layer, and Point drop-down list to select the 
zone, layer, and endpoint location you want to see.
Click the Diagram button to access the Layer Point Conditions 
property view.
Layer Point Conditions Property View
The Layer Point Conditions property view displays the detailed 
temperatures and overall heat transfer values for both endpoints 
of the selected layer.
You can select a different layer using the Layer drop-down list.
Click the View Holdup button to access the Holdup property 
view. 
The information displayed on this page is not central to the 
performance of the LNG operation.
 Figure 4.105
Indicates the flow direction in the selected layer.
Refer to Section 1.3.4 - 
HoldUp Property View 
for more information.4-192
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Th4.5.7 Dynamics Tab
The Dynamics tab contains the following pages: 
• Model
• Specs
• Holdup 
• Estimates
• Stripchart
Model Page
On the Model page, you can specify how each layer in a multi-
zone LNG unit operation is connected.
If you are working exclusively in steady state mode, you are 
not required to change any information on the pages 
accessible through this tab.
 Figure 4.1064-193
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ThMain Settings
The Main Settings group displays the following LNG model 
parameters:
The Connections group displays the feed and product streams of 
each layer for every zone in the LNG unit operation. Every layer 
must have one feed stream and one product stream in order for 
the LNG operation to solve. A layer’s feed or product stream can 
originate internally (from another layer) or externally (from a 
material stream in the simulation flowsheet). Thus, various 
different connections can be made allowing for the modeling of 
multi-pass streams in a single zone.
Parameter Description
Number of 
Zones
The number of zones in a LNG unit operation can be 
specified in this field.
Elevation You can specify the elevation of the LNG in this field. The 
elevation is significant in the calculation of static head in 
and around the LNG unit operation.
Combine 
Layers 
Checkbox
With the Combine Layers checkbox selected, individual 
layers (holdups) carrying the same stream in a single zone 
is calculated using a single holdup. 
The Combine Layers option increases the speed of the 
dynamic solver, and usually yields results that are similar to 
a case not using the option.
 Figure 4.1074-194
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ThConnections Group
Every zone in the LNG unit operation is listed in the Zone drop-
down list in the Connections group. All the layers in the selected 
zone in one set appear. For every layer’s feed and product, you 
must specify one of the following:
• An external material stream.
• The zone and layer of an internal inlet or exit stream.
You can specify the relative direction of flow in each layer in the 
zone. Layers can flow counter (in the opposite direction) or 
across the direction of a reference stream. The reference stream 
is defined as a stream which does not have either the Counter 
or Cross checkbox selected in the Connections group. 
The following table lists three possible flow configurations:      
Description Flow Direction Flow Setting
Counter 
Current Flow
Parallel Flow
Cross Flow
To implement counter current flow for two streams in a 
single exchanger block, ensure that the Counter checkbox is 
selected for only one of the streams. If the Counter checkbox 
is selected for both streams, the flow configuration is still 
parallel, and in the opposite direction.4-195
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ThSpecs Page
The Specs page contains information regarding the calculation 
of pressure drop across the LNG unit operation.
The following parameters appear for every layer in each zone in 
the LNG unit operation in the Dynamic Specification groups.
 Figure 4.108
Dynamic 
Specification
Description
Delta P 
Calculator
The Delta P Calculator allows you to either specify or 
calculate the pressure drop across the layer in the LNG 
operation. Specify the cell with one of following options:
• user specified. You specify the pressure drop.
• not specified. Pressure drop across the layer is 
calculated from a pressure flow relationship. You must 
specify a k-value, and select the Flow Eqn checkbox if 
you want to use this non specified Delta P calculator.
Delta P The pressure drop across the layer of the LNG operation 
can be specified or calculated.
Flow eqn Activate this option, if you want to have the Pressure Flow k 
value used in the calculation of pressure drop. If the Flow 
Eqn checkbox is selected, the Delta P calculator must also 
be set to not specified. 4-196
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ThWhen you click the Generate Estimates button, the initial 
pressure flow conditions for each layer are calculated. HYSYS 
generates estimates using the assumption that the flow of a 
particular stream entering the exchanger block (zone) is 
distributed equally among the layers. The generated estimates 
appear on the Estimates page of the Dynamics tab. It is 
necessary to complete the Estimates page in order for the LNG 
unit operation to solve.
It is strongly recommended that you specify the same pressure 
drop calculator for layers that are connected together in the 
same exchanger block or across adjacent exchanger blocks. 
Complications arise in the pressure flow solver if a stream’s flow 
is set in one layer, and calculated in the neighbouring layer.
The Automatically Update k’s checkbox automatically updates 
the k’s based on current relationships between P-F flow rates 
and pressure drops for all the heat transfer layers, making the 
LNG steam flow rates more stable.
Laminar HYSYS is able to model laminar flow conditions in the layer. 
Select the Laminar checkbox if the flow through the layer 
is in the laminar flow regime.
Pressure 
Flow k Value
The k-value defines the relationship between the flow 
through layer and the pressure of the surrounding streams. 
You can either specify the k-value or have it calculated from 
the stream conditions surrounding the layer. You can “size” 
each layer in the zone with a k-value by clicking the 
Calculate k’s button. Ensure that there is a non zero 
pressure drop across the LNG layer before the Calculate k 
button is clicked. Each zone layer can be specified with a 
flow and set pressure drop by clicking the Generate 
Estimates button.
The LNG unit operation, like other dynamic unit operations, 
should use the k-value specification option as much as 
possible to simulate actual pressure flow relations in the 
plant.
Dynamic 
Specification
Description4-197
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ThHoldup Page
The Holdup page contains information regarding each layer’s 
holdup properties, composition, and amount.
The Details group contains detailed holdup properties for every 
layer in each zone of the LNG. In order to view the advanced 
properties for individual holdups, you must first select the 
individual holdup.
To choose individual holdups you must specify the Zone and 
Layer in the corresponding drop-down lists. 
 Figure 4.109
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 4-198
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ThEstimates Page
The Estimates page contains pressure flow information 
surrounding each layer in the LNG unit operation:
The following pressure flow information appears on the 
Estimates page:
• Delta P
• Inlet Pressure
• Outlet Pressure
• Inlet Flow
• Outlet Flow
It is necessary to complete the Estimates page in order for the 
LNG unit operation to completely solve. The simplest method of 
specifying the Estimates page with pressure flow values is 
having HYSYS estimate these values for you. This is achieved by 
clicking the Generate Estimates button on the Specs page of the 
Dynamics tab. HYSYS generates estimates using the assumption 
that the flow of a particular stream entering the exchanger block 
(zone) is distributed equally among the layers.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
 Figure 4.110
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.4-199
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Th4.5.8 HTFS-MUSE Tab
The HTFS-MUSE tab integrates the HTFS’ MUSE application into 
the HYSYS LNG unit Calculation. HYSYS can use the MUSE and 
MULE calculation Engines.
MUSE can perform a range of calculations on plate-fin heat 
exchangers, either simple two-stream exchangers, or complex 
ones with multiple streams. The basic calculation options are 
described in the table below:
These calculation types all relate to co- or counter-current 
exchangers.
The HTFS-MUSE tab contains two buttons:
• Import. Allows you to import values from MUSE into the 
pages of the tab.
• Export. Allows you to export the information provided 
within this tab to MUSE.
Calculation Modes Description
Simulation Determines the heat load, pressure changes and 
outlet conditions for each stream in the exchanger, 
based on an exchanger you specify, and given 
stream inlet conditions.
Layer by Layer 
Simulation
For the simulation of a plate fin heat exchanger on 
a layer by layer basis. It must be specified with a 
layer pattern. It predicts temperature profiles 
through the layer pattern, which can be used to 
assess how good the layer pattern is.
Thermosyphon Determines the performance of an exchanger, with 
a geometry you specify, with one stream operating 
as a thermosyphon. The exchanger can either be 
internal to the column or outside it and connected 
via pipe work. You can specify either the head of 
liquid driving the thermosyphon flow, or the 
thermosyphon stream flowrate, leaving the 
program to calculate the one you do not specify.
Design Produces a “first shot” design of a heat exchanger 
to meet a heat load duty and pressure drop limits, 
which you specify for each stream. This should be 
a useful indication of what a specialist 
manufacturer would provide. A final design of a 
plate-fin exchanger must, however, come from a 
manufacturer, who can use proprietary finning and 
specialist design and manufacturing techniques.4-200
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ThThe HTFS-MUSE tab contains the following pages:
• Exchanger
• Process
• Distributors
• Layer Pattern
• Fins
• Design Limits
• Stream Details
• Methods
• Results
Exchanger Page
The Exchanger page allows you to specify parameters that 
define the geometric configuration of the exchanger, as well as 
the stream.
 Figure 4.1114-201
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ThThe group located on the top of the page is for specifying the 
stream geometry and consists of the following fields:
The remainder of the groups located on this page are for 
specifying the exchangers geometry and consists of the 
following fields:
Field Description
Flow 
Direction
There are two options that you can choose from to define 
the Flow direction of the stream.
• flow away from end A, Up (B to A).
• flow towards end A, Down (A to B).
Normal design practice is for hot streams to flow away from 
end A (which is at the top of the exchanger), while cold 
streams flow towards end A.
Number of 
Layers
Allows you to enter the total number of layers a stream 
occupies in the exchanger. If there is more than one 
exchanger in parallel, enter the number for one exchanger 
only.
This item can be omitted if a layer pattern is specified. If 
you specify both, however, they are cross-checked, which 
can be useful in detecting errors in a layer pattern input. 
When they are inconsistent, a warning is produced.
If a stream is re-distributed, and occupies extra layers for 
part of its length, enter the basic number of layers only 
here, and specify the additional layers on the Distributors 
page.
Distance to 
Start of Main 
Fin
Allows you to enter the distance to the start of a stream's 
main finning from the fixed reference point. If omitted, the 
default is zero.
If this distance is less than the distance to the start of the 
effective length, then there is a region of main fin where 
pressure drop, but no heat transfer is evaluated. If this 
distance is greater than that to the start of the effective 
length, then the stream has a draw-on or draw-off point 
part way along the exchanger.
Field Description
Orientation Plate Fin heat exchangers are normally vertical, with 
flow up or down. Enter 1.0 for vertical exchangers with 
the reference end, A, at the top. For horizontal or 
inclined exchangers, refer to the MUSE help file.
Exchangers in 
Parallel
More than one exchanger in parallel can be used when 
stream flowrates, or thermal duties are too large to be 
handled by a single exchanger. In all cases the 
exchangers are assumed to be identical, and no 
calculations are performed on pressure losses in 
connecting pipe work.
Effective Width The effective flow width is the total width of the 
exchanger less the widths of the two side bars.4-202
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ThProcess Page
Exchanger Metal Plate Fin exchangers for LNG and other cryogenic 
duties are made of aluminium. For other exchangers, 
you can select from:
• aluminium
• stainless steel
• titanium
Parting Sheet 
Thickness
The thickness of the separating plates (parting sheets) 
between layers is used to determine the exchanger 
stack height, and also has an effect on the metal 
resistance to heat transfer.
Side Bar Width Side bars form the sides and ends of each layer. This 
item does not usually affect the calculated results, with 
the exception of longitudinal conduction calculations.
Cap Sheet 
Thickness
The stack height is the sum of the fin heights and 
parting sheet thicknesses for every layer in the 
exchanger, plus the thickness of the two side plates 
(cap sheets).
Fin Number for 
Empty Layer
If you specify a layer pattern with some layers 
containing no streams enter the fin number to identify 
the fins used in such layers.
 Figure 4.112
Field Description4-203
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ThThe Process page allows you to specify the following process 
information for the streams attached to your exchanger:
• Estimated Pressure Drop
• Fouling Resistance
• Heat Load
• Design Pressure
Distributors Page
Distributors are special regions of finning, usually laid at an 
angle, that directs the flow between a header (inlet or outlet) 
and the main heat transfer finning. A low frequency perforated 
fin is usually used - for example 6fpi, 25% perforated. 
Distributor data is optional for each stream.  If omitted the 
distributor pressure drop for that stream is ignored.
Heat transfer in inlet and outlet distributors is not considered, 
but if all streams have distributor data specified, an estimate is 
made of the heat transfer margin associated with each 
distributor. When distributor pressure drops are calculated, an 
estimate is made of the risk of maldistribution across the width 
of each layer.
When Redistribution is used, you should specify the 
Redistributor, and corresponding re-inlet distributor. 
Redistributors associated with partial draw-off of streams can 
also be specified. 4-204
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ThEach distributor type consists of a set of inputs as shown in the 
figure below.
• Inlet/Outlet Distributor Type
 Figure 4.113
Field Description
Type Allows you to specify the redistributor type, and the 
side of the exchanger on which the associated header 
is located. You have seven options:
• Full End
• End-Side
• Central
• Diagonal
• Mitred
• Indirect
• Hardway
Header Location Allows you to specify the side of the exchanger that the 
header is located. You have four options:
• Right side
• Left side
• Central
• Twin
Fin Number for 
Pad 1 and 2
Numbers to identify the fins used in the inlet/outlet 
distributor pads. Distributors typically use 6fpi 255 
perforated finning. The same fin is usually used in both 
pads, so only pad 1 need normally be specified. Pad 1 
is adjacent to the header.
Dimension a 
(axial length)
Dimension a for the inlet/outlet distributor. Dimension 
a is the length along the exchanger occupied by the 
distributor.4-205
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Th• Redistributor Type
Dimension b Dimension b for the inlet/outlet distributor. This is the 
header diameter for End Side, Central, Indirect and 
Hardway distributors, and the Pad 1 length for Mitred 
distributors. It is not needed for Full End of Diagonal 
distributors.
Nozzle DIameter The internal diameter of the inlet/outlet nozzle. If 
omitted the inlet/outlet nozzle pressure loss is not 
calculated.
Field Description
Type Allows you to specify the redistributor type, and the 
side of the exchanger on which the associated header 
is located. You have four options:
• Standard
• Twin
• Hardway
• Hardway Twin
Header Location Allows you to specify the side of the exchanger that the 
header is located. You have three options:
• Right side
• Left side
• Twin
Distance to 
Redistributor
Allows you to specify the distance to the redistributor 
from the inlet.
Fin Number for 
Pad 1, 2, and 3
Numbers to identify the fins used in the redistributor. 
The same fin is usually used in all pads, so only pad 1 
need normally be specified. In a dividing redistributor, 
flow that remains in the layers flows through Pad 1 
then Pad 2, while Pad 3 carries the flow that goes to 
other layers.
Dimension a 
(axial length)
Dimension a, the length along the exchanger occupied 
by the redistributor.
Dimension b Dimension b for the redistributor. In a conventional 
dividing redistributor, this is the entry width associated 
with the flow that remains in the same layer.
Field Description4-206
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Heat Transfer Operations 4-207
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Th• Re-Inlet Distributor Type
Layer Pattern Page
The Layer Pattern page allows you to define the sequence of 
stream numbers that comprise the exchanger. 
Field Description
Type Allows you to specify the re-inlet distributor type. This can be in any 
form of side entry/exit distributor. You have five options:
• None
• Diagonal
• Mitred
• Indirect
• Hardway
Fin Number for 
Pad 1 and 2
Numbers to identify the fins used in the re-inlet distributor pads. The 
same fin is usually used in both pads, so only pad 1 need normally 
be specified. Pad 1 is adjacent to the header.
Dimension a 
(axial length)
Dimension a, the length along the exchanger occupied by the re-
inlet distributor.
Dimension b Dimension b for the re-inlet distributor.
Extra Layers/
Draw Off 
Fraction
For  a re-inlet distributor that directs flow to a number of extra 
layers, enter the number of extra layers.
For a re-inlet distributor that collects from the extra layers, to direct 
it back to the basic number of layers, enter the number of extra 
layers with a minus sign.
If there are no extra layers, but the stream is partially drawn off, 
enter the fraction of the stream that is drawn off.
 Figure 4.1144-207
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ThThe layer pattern itself gives the sequence of layers, while the 
Layer Definition table lets you define the sequence of streams in 
each layer. The layer pattern is mandatory input for Layer-by-
Layer simulations, but optional for stream by stream. If no layer 
pattern is provided, the number of layers for each stream must 
be specified.
Layer Pattern
Enter the sequence of layers forming the layer pattern (stacking 
pattern).  The pattern can be identified as a sequence of  layer 
identifiers, each identified by a letter, such as ABABABCAB. 
Though in simple cases, for example when there is only one 
stream per layer, the layer pattern can be specified as sequence 
of streams, for example 121213412.
Repeated sequences can be written in brackets, for example 
(121213/5)1312 means that the sequence 121213 occurs five 
times, followed by 1312. Spaces in the pattern are ignored, and 
brackets cannot be embedded in brackets. A stream number’s 
sequence can contain zeros to indicate completely empty layers.
A layer pattern can terminate in M or MM to indicate that the 
pattern has central symmetry. MM indicates that the central 
layer is repeated, M that the symmetry is about the centre of 
the final layer. When The pattern is defined in terms of letters, 
use | or ||, not M's, to indicate mirror symmetry.
Layer Definition
For each (alphabetic) layer identifier in the pattern specify the 
stream or sequence of streams along the exchanger from end A, 
within each layer type. This is only needed when a pattern is 
defined in terms of layer types (A, B, C, and so forth) rather 
than streams (1, 2, 4, and so forth).
The Layer Definition facility is only available in MUSE 3.20 
and later versions.4-208
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ThFins Page
The Fins page allows you to specify data on fin geometry. 
When a fin is specified, the corresponding fin performance data 
from the fin manufacturer (friction factors and Colburn j factors 
over a range of Reynolds numbers) should be input when 
available. If they are not available, they are estimated using 
generalized HTFS correlations for particular fin types.
Fin numbers are used to identify the particular fin used as main 
fin or distributor fin for each stream. Fin numbers up to 20 
identify fins that data is specified in the program input.
The Fin Geometry groups consists of two buttons and a table. 
The two buttons allows you to add and remove fins from the 
heat exchanger, while the table allows you to specify each fin’s 
geometry. 
 Figure 4.1154-209
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ThThe table consists of the following fields.
As mentioned above the corresponding fin performance data 
from the fin manufacturer, if available, should be entered into 
the Fin Performance group. To specify the data, select the fin 
number from the list of fins, and enter the data in the 
appropriate fields.
Field Description
Fin Type There are four main types of fin
• Plain
• Perforated
• Serrated, or offset-strip
• Wavy or herringbone
For details of when each type should be used, refer to 
the MUSE Help file.
Prandtl No. 
Correlation to Cj
This parameter is important for high viscosity fluids in 
plain or perforated fins.
The Colburn j factor assumes that Cj is a function of Re 
only, but this is not true at low Reynolds numbers 
(below 1000), where there is also Prandtl number 
dependence.
If you specify the Re-f-Cj data at a Pr appropriate to 
the fluids used, omit this item. If you specify the Pr=1 
data, specify 1 for a full correction, or a value between 
0 and 1 for a partial correction. Refer to the MUSE Help 
file for more details.
Fin Height Distance between the separating plates (parting 
sheets). This applies to all fin types.
All the fins (main fin and distributor) for a stream must 
have the same height.  A warning is issued if this is not 
so.
Fin Thickness The fin thickness.
Fin Frequency Number of fins per unit of length. This item can be zero 
if no fins are present.
Common fin frequencies are 16, 18 or 21 ft/in for main 
fins, and 6 or 8 ft/in for distributor fins.
Fin Porosity For perforated fins, enter the fin porosity as a fraction 
of the metal lost as holes.
Fin Serration 
Length
For serrated fins enter the fin serration length. The 
default is 3 mm (approximately 1/8 inch), which is 
typical of values used by most manufacturers.
This input item is only needed for long-serration length 
serrated fins.4-210
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ThDesign Limits Page
In the future version of HYSYS, the HTFS design capability will 
be available on the Design Limits page.
Stream Details Page
The Stream Details page allows you to specify more stream 
geometry data that supplements the data that was entered on 
the Exchanger page.
 Figure 4.1164-211
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ThThe following table defines each of the fields on this page.
Field Description
Same Layer as 
Stream
The Same Layer as Stream parameter is one way 
of specifying that two streams occupy the same 
set of layers in an exchanger. It is not needed, if 
you specify a layer pattern in terms of Layer 
Identifiers A, B, C, and so forth, with Layer 
Definition information.
If you specify a layer pattern in terms of stream 
numbers, then one stream in each layer is used to 
identify that layer. For other streams in that layer 
give the number of the stream in the layer pattern 
that identifies the layer.
Fraction of Double 
Banking
The Fraction of Double Banking parameter is not 
needed if you specify a layer pattern, and is 
estimated if you do not. Refer to the MUSE Help 
for a definition and more details.
Number of Cross 
Flow Passes
For streams in multipass crossflow, enter the 
number of crossflow passes.
Fin Number of (first) 
Main Fin
Number to identify the main heat transfer fin for 
the stream. The number must correspond to one 
of the fin data blocks in the Fins page, or to a fin in 
a User Databank.
If the stream uses more than one type of main fin, 
this item is the first fin, counting from the stream 
inlet.
Length of (first) Main 
Fin
The length of the main fin for the stream.
Fin Number for 
Second to Sixth Fins
For a stream that uses more than one type of main 
fin, enter the fin numbers. The sequence is from 
stream inlet to outlet.
Length of Fins for 
Second to Sixth Fins
The length of each main fin for the stream.4-212
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ThMethods Page
The Methods page consists of three groups:
• Calculation Options
• Calculation Parameters
• Process Constraints
Calculation Options Group
The Calculation Options group is used to configure the data that 
appears on the Results page. Only the Output Units need 
normally be set, as defaults are usually acceptable for all other 
items. 
 Figure 4.1174-213
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ThThe group consists of the following fields. 
Field Description
Calculation Type The Calculation Type should not be set. It gives access 
to a deprecated calculation facility, Length estimation, 
as an alternative to Normal simulation. Refer to the 
MUSE help file for more information.
Units of Output Allows you to specify the set of units you want to use 
for the output data. There are five options to choose 
from:
• SI / deg C
• British
• Metric / C
• SI / deg K
• Metric / K
Output of Input 
Data
Specifies where the output of input data appears in the 
main Results page (lineprinter output). Refer to the 
MUSE help for more information.
Physical 
Properties 
Package
Allows you to send the Physical Properties of the 
exchanger to the Results page or to a specific file.
Convergence 
Parameter
Use only if MUSE shows convergence problems. Refer 
to the MUSE help for more information.
Stream by 
Stream or Layer 
by Layer
Normally leave this item unset. Use it only with the 
(MULE) layer-by-layer calculation engine to enforce a 
reduced stream-by-stream calculation. Refer to the 
MUSE help for more information.
Longitudinal 
Conduction
You can specify that in addition to heat transfer 
between streams, allowance can be made for heat 
conducted in the exchanger metal from the hot to cold 
end of the exchanger. This can be important for 
exchangers used in liquefying hydrogen or helium. 
Refer to the MUSE help for more information.
Number of 
Calculation Steps
Calculations in MUSE use a number of equal length 
steps along the exchanger. The default is 100, the 
maximum 200. Refer to the MUSE help file for more 
information.
1st Est. Heat 
Load (fraction of 
max)
Use this item only if there are convergence problems. 
It lets you change the initial estimate of exchanger 
duty. Refer to the MUSE help file for more information.
Distributor 
Calculations
Gives you control over when distributor pressure losses 
are calculated. The default is that losses are calculated 
if you specify distributor data. Refer to the MUSE help 
for more information.
Maximum 
Number of 
Iterations
Enter a value if you want to restrict the number of 
iterations. Refer to the MUSE help file for more 
information.4-214
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ThCalculation Parameters Group
The Calculation Parameters group allows you to specify process 
exchanger parameters. The group consists of the following 
fields:
Process Constraints Group
The Process Constraints group allows you to specify sets of 
stream constraints for over-riding, or scaling values normally 
calculated by the program. These should not be used, unless 
you have a good reason for doing so.
Field Description
Heat Leak It is possible to specify a net heat leak into the 
exchanger, or out of the exchanger, if a negative value 
is specified.
Heat Leak 
Skewness
For heat leaks that are not uniform along the 
exchanger length. Refer to the MUSE help for more 
information.
Effective Length, 
Distance to 
Effective Length
These two fields should normally be omitted, and left 
to the program to calculate. The effective length is that 
region of the exchanger where heat transfer is 
assumed to occur. It is determined from the exchanger 
geometry data, but you can override the program if 
you want. Refer to the MUSE help for more 
information.
A Stream - B 
Stream Load
A deprecated input. It is possible to specify the heat 
load across the exchanger for end A to end B.
Field Description
Liquid Phase HTC You can enter a value for the liquid heat transfer 
coefficient here to override the calculated value.
It is recommended that the program calculated values 
be used.
Two Phase HTC You can enter a value for the two phase (boiling or 
condensing) heat transfer coefficient here to override 
the calculated value.
It is recommended that the program calculated values 
be used.
Vapour Phase 
HTC
You can enter a value for the vapour heat transfer 
coefficient here to override the calculated value.
It is recommended that the program calculated values 
be used.4-215
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ThResults Page
The exchanger results appear on this page. The results are 
created in a text format that can be exported to HTFS-MUSE.
4.6 References
 1 Perry, R.H. and D.W. Green. Perry’s Chemical Engineers’ Handbook 
(Seventh Edition) McGraw-Hill (1997) p. 11-33
 2 Perry, R.H. and D.W. Green. Perry’s Chemical Engineers’ Handbook 
(Seventh Edition) McGraw-Hill (1997) p. 11-42
 3 Kern, Donald Q. Process Heat Transfer McGraw-Hill International 
Editions: Chemical Engineering Series, Singapore (1965) p. 139
Multiplier for 
Liquid 
Coefficient
A value entered here can be used to increase or 
decrease the calculated liquid heat transfer coefficient. 
It also scales any pre-set coefficient you input.
It is recommended that the program calculated values 
be used.
Multiplier for 
Two Phase 
Coefficient
A value entered here can be used to increase or 
decrease the calculated boiling or condensing heat 
transfer coefficient. It also scales any pre-set 
coefficient you input.
It is recommended that the program calculated values 
be used.
Multiplier for 
Vapour 
Coefficient
A value entered here can be used to increase or 
decrease the calculated vapour or gas heat transfer 
coefficient. It also scales any pre-set coefficient you 
input.
It is recommended that the program calculated values 
be used.
Pressure Drop 
Multiplier
Enter the number that the calculated frictional 
pressure gradient (liquid, two phase or vapour) should 
be multiplied.  It is not possible to scale the pressure 
drops of each phase separately.
It is recommended that the program calculated values 
be used.
Precalculated 
Arrays Flag
Allows you to override an internal calculation flag, it is 
best left unset. See the MUSE help for more details.
Preset deltaT for 
Boiling
Provides a variant on the boiling method, it is best left 
unset. See the MUSE help for more details.
Field Description4-216
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Th5  Logical Operationsw.cadfamily.com    EMa
e document is for study 5.1  Adjust ............................................................................................ 4
5.1.1  Adjust Property View ................................................................ 5
5.1.2  Connections Tab....................................................................... 6
5.1.3  Parameters Tab ........................................................................ 8
5.1.4  Monitor Tab ........................................................................... 14
5.1.5  User Variables Tab.................................................................. 16
5.1.6  Starting the Adjust ................................................................. 17
5.1.7  Individual Adjust .................................................................... 18
5.1.8  Multiple Adjust....................................................................... 18
5.2  Balance ........................................................................................ 19
5.2.1  Balance Property View ............................................................ 20
5.2.2  Connections Tab..................................................................... 21
5.2.3  Parameters Tab ...................................................................... 22
5.2.4  Worksheet Tab ....................................................................... 27
5.2.5  Stripchart Tab........................................................................ 27
5.2.6  User Variables Tab.................................................................. 27
5.3  Boolean Operations...................................................................... 28
5.3.1  Boolean Logic Blocks Property View .......................................... 29
5.3.2  And Gate .............................................................................. 34
5.3.3  Or Gate ................................................................................ 35
5.3.4  Not Gate ............................................................................... 36
5.3.5  Xor Gate ............................................................................... 37
5.3.6  On Delay Gate ....................................................................... 38
5.3.7  Off Delay Gate ....................................................................... 39
5.3.8  Latch Gate ............................................................................ 40
5.3.9  Counter Up Gate .................................................................... 41
5.3.10  Counter Down Gate .............................................................. 42
5.3.11  Cause and Effect Matrix......................................................... 435-1
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The document is for study 5.4  Control Ops...................................................................................56
5.4.1  Adding Control Operations........................................................56
5.4.2  Split Range Controller..............................................................58
5.4.3  Ratio Controller ......................................................................80
5.4.4  PID Controller.......................................................................101
5.4.5  MPC Controller......................................................................132
5.4.6  DMCplus Controller ...............................................................155
5.4.7  Control Valve........................................................................171
5.4.8  Control OP Port.....................................................................175
5.5  Digital Point................................................................................176
5.5.1  Digital Point Property View .....................................................176
5.5.2  Connections Tab....................................................................177
5.5.3  Parameters Tab.....................................................................178
5.5.4  Stripchart Tab.......................................................................184
5.5.5  User Variables Tab.................................................................184
5.5.6  Alarm Levels Tab...................................................................185
5.6  Parametric Unit Operation ..........................................................186
5.6.1  Parametric Unit Operation Property View ..................................187
5.6.2  Design Tab ...........................................................................187
5.6.3  Parameters Tab.....................................................................195
5.6.4  Worksheet Tab......................................................................196
5.7  Recycle .......................................................................................197
5.7.1  Recycle Property View............................................................198
5.7.2  Connections Tab....................................................................199
5.7.3  Parameters Tab.....................................................................200
5.7.4  Worksheet Tab......................................................................208
5.7.5  Monitor Tab ..........................................................................208
5.7.6  User Variables Tab.................................................................209
5.7.7  Calculations .........................................................................209
5.7.8  Reducing Convergence Time...................................................210
5.7.9  Recycle Assistant Property View ..............................................211
5.8  Selector Block.............................................................................215
5.8.1  Selector Block Property View ..................................................215
5.8.2  Connections Tab....................................................................216
5.8.3  Parameters Tab.....................................................................217
5.8.4  Monitor Tab ..........................................................................2205-2
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5-3 Logical Operations 
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The document is for study 5.8.5  Stripchart Tab.......................................................................221
5.8.6  User Variables Tab.................................................................221
5.9  Set..............................................................................................222
5.9.1  Set Property View .................................................................222
5.9.2  Connections Tab....................................................................223
5.9.3  Parameters Tab.....................................................................224
5.9.4  User Variables Tab.................................................................225
5.10  Spreadsheet..............................................................................225
5.10.1  Spreadsheet Property View...................................................226
5.10.2  Spreadsheet Functions.........................................................227
5.10.3  Spreadsheet Interface..........................................................232
5.10.4  Spreadsheet Tabs................................................................237
5.11  Stream Cutter ...........................................................................244
5.11.1  Stream Cutter Property View ................................................245
5.11.2  Design Tab .........................................................................253
5.11.3  Transitions Tab....................................................................254
5.11.4  Worksheet Tab ....................................................................261
5.12  Transfer Function .....................................................................261
5.12.1  Transfer Function Property View ............................................263
5.12.2  Connections Tab..................................................................264
5.12.3  Parameters Tab ...................................................................264
5.12.4  Stripchart Tab.....................................................................277
5.12.5  User Variables Tab...............................................................277
5.13  Common Options ......................................................................278
5.13.1  ATV Tuning Technique ..........................................................278
5.13.2  Controller Face Plate............................................................2795-3
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Th5.1 Adjust
The Adjust operation varies the value of one stream variable 
(the independent variable) to meet a required value or 
specification (the dependent variable) in another stream or 
operation.
In a flowsheet, a certain combination of specifications may be 
required, which cannot be solved directly. These types of 
problems must be solved using trial-and-error techniques. To 
quickly solve flowsheet problems that fall into this category, the 
Adjust operation can be used to automatically conduct the trial-
and-error iterations for you.
The Adjust is extremely flexible. It allows you to link stream 
variables in the flowsheet in ways that are not possible using 
ordinary “physical” unit operations. It can be used to solve for 
the desired value of just a single dependent variable, or multiple 
Adjusts can be installed to solve for the desired values of several 
variables simultaneously.
The Adjust can perform the following functions:
• Adjust the independent variable until the dependent 
variable meets the target value.
• Adjust the independent variable until the dependent 
variable equals the value of the same variable for 
another object, plus an optional offset.
The Adjust is a steady state operation; HYSYS ignores it in 
dynamic mode.
The Independent variable cannot be a calculated value; it 
must be specified.5-4
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Th5.1.1 Adjust Property View
There are two ways that you can add an Adjust to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Adjust.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing the F4.
2. Double-click the Adjust icon. 
The Adjust property view appears.
 Figure 5.1
Adjust icon5-5
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Th5.1.2 Connections Tab
The first tab of the Adjust property view, as well as several other 
logicals, is the Connections tab. The tab contains the following 
pages:
• Connections
• Notes
Connections Page
The Connections page comprises of three groups:
• Adjusted Variable
• Target Variable
• Target Value
Adjusted/Target Variable Groups
The Adjusted and Target Variable groups are very similar in 
appearance, each containing an Object field, Variable field, and 
a Select Var button. 
• The Adjusted Object is the owner of the independent 
variable which is manipulated in order to meet the 
specified value of the Target variable. 
• The Target Object is the owner of the dependent variable 
whose value you are trying to meet. A Target Object can 
be a unit operation, stream, or a utility.
 Figure 5.25-6
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Th• The Select Var button enables you to select a variable 
for the Adjusted and Target objects.
Target Value Group
Once the target object and variable are defined, there are three 
choices for how the target is to be satisfied:
• If the target variable is to meet a certain numerical 
value, select the User Supplied radio button (as shown 
in the figure below), and enter the appropriate value in 
the Specified Target Value field.
• If the target variable is to meet the value (or the value 
plus an offset) of the same variable in another stream or 
operation, select the Another Object radio button (as 
shown in the figure below), and select the stream or 
operation of interest from the Matching Value Object 
drop-down list. If applicable, enter an offset in the 
available field.
• If the target variable is to meet the value (or the value 
plus an offset) of the same variable specified in the 
spreadsheet, select the SpreadSheetCell Object radio 
button (as shown in the figure below), and select the cell 
that you want from the Matching Value Object drop-down 
 Figure 5.3
 Figure 5.4
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-7
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5-8 Adjust
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Thlist. This allows the SpreadSheetCell to be attached as an 
adjusted variable, and source to the target variable. You 
can also specify the offset in the available field.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the operation or to your 
simulation case in general.
5.1.3 Parameters Tab
Once you have chosen the dependent and independent 
variables, the convergence criteria must be defined. This is 
usually done on the Parameters tab. The Parameters tab has two 
pages:
• Parameters
• Options
Parameters Page
The Parameters page allows you to specify the adjust 
parameters:
 Figure 5.5
Solving Parameter Description
Simultaneous 
Solution
Solves multiple Adjust loops simultaneously. There 
is only one simultaneous solving method available 
therefore when this checkbox is selected the 
Method field is no longer visible.
Method Sets the (non-simultaneous) solving method: 
Secant or Broyden.
Tolerance Sets the absolute error. In other words, the 
maximum difference between the Target Variable 
and the Target Value.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.5-8
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ThChoosing the Solving Methods
Adjust loops can be solved either individually or simultaneously. 
If the loop is solved individually, you have the choice of either a 
Secant (slow and sure) or Broyden (fast but not as reliable) 
search algorithm. The Simultaneous solution method uses 
modified Levenberg-Marquardt method search algorithm. A 
single Adjust loop cannot be solved in the Simultaneous mode. 
In Simultaneous mode, the adjust variable is adjusted after the 
last operation in the flowsheet has solved. The calculation level 
has no effect on the Adjust operation in the Simultaneous mode.
When the Simultaneous Solution checkbox is selected, the 
Step Size The initial step size employed until the solution is 
bracketed.
Maximum / 
Minimum 
The upper and lower bounds for the independent 
variable (optional) are set in this field.
Maximum 
Iterations 
The number of iterations before HYSYS quits 
calculations, assuming a solution has not been 
obtained.
Sim Adj Manager Opens the Simultaneous Adjust Manager allowing 
you to monitor and modify all Adjusts that are 
selected as simultaneous.
Optimizer 
Controlled
Passes a variable and a constant to the optimizer. 
When activated the efficiency of the simultaneous 
Adjust is increased. This option requires RTO.
The Calculation Level for an Adjust (accessed under Main 
Properties) is 3500, compared to 500 for most streams and 
operations. This means that the Adjust is solved last among 
unknown operations. You can set the relative solving order 
of the Adjusts by modifying the Calculation Level.
Solving Parameter Description5-9
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ThMethod field is no longer visible.
Simultaneous Adjust Manager
The Simultaneous Adjust Manager (SAM) property view allows 
you to monitor, and modify all Adjusts that are selected as 
simultaneous. This gives you access to a more efficient method 
of calculation, and more control over the calculations.
The SAM property view is launched by clicking the Sim Adj 
Manager button on the Parameters tab, or by selecting 
Simultaneous Adjust Manager command from the 
Simulation menu.
The SAM property view contains the following tabs:
• Configuration
• Parameters
• History
 Figure 5.6
All adjusts from old cases in Simultaneous mode are 
automatically added to the SAM.
The SAM requires two or more active (in other words, not 
ignored) adjusts to solve. If you are using only one adjust, 
you cannot use the SAM.5-10
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ThThe SAM property view also contains the following common 
objects at the bottom of the property view:
• The status bar, which displays the status of the SAM 
calculation.
• The Stop and Start buttons, which are used to start and 
stop the SAM calculations repectively.
• The Ignored checkbox, which enables you to toggle on 
and off the SAM feature and all of the selected Adjusts 
simultaneously.
Configuration Tab
The Configuration tab displays information regarding Adjusts 
that have been selected as simultaneous. You can view the 
individual Adjusts by double-clicking on the Adjust name. You 
can also modify the target value or matching value object, 
value, and offset. This tab also allows you to ignore individual 
Adjusts.
Parameters Tab
The Parameters tab allows you to modify the tolerance, step 
size, max, and min values for each Adjust, as well as, displays 
the residual, number of iterations the SAM has taken, and the 
 Figure 5.75-11
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5-12 Adjust
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Thiteration status. This tab also allows you to specify some of the 
calculation parameters as described in the table below.
History Tab
The History tab displays the target value, adjusted value, and 
residual value for each iteration of the selected Adjust(s). One 
or more Adjusts can be displayed by clicking on the checkbox 
beside the Adjust name. The Adjusts are always viewed in order 
from left to right across the page. For example, if you are 
viewing Adjust 2 and add Adjust 1 to the property view, Adjust 1 
becomes the first set of numbers, and Adjust 2 is shifted to the 
right.
Parameter Description
Type of 
Jacobian 
Calculation
Allows you to select one of three Jacobian calculations:
• ResetJac. Jacobian is fully calculated and values reset 
to initial values after each jacobian calculation step. 
Most time consuming but most accurate.
• Continuous. Values are not recalculated between 
Jacobian calculation steps. Quickest, but allows for 
“drift” in the Jacobian therefore not as accurate.
• Hybrid. Hybrid of the above two methods.
Type of 
Convergence
Allows you to select one of three convergence types:
• Specified. SAM is converged when all Adjusts are 
within the specified tolerances.
• Norm. SAM is converged when the norm of the 
residuals (sums of squares) is less then a user 
specified value.
• Either. SAM is converged with which ever of the 
above types occurs first.
Max Step 
Fraction
The number x step size is the maximum that the solver is 
allowed to move during a solve step.
Perturbation 
Factor
The number x range (Max - Min) or the number x 100 x 
step size (if no valid range). This is the maximum that the 
solver is allowed to move during a Jacobian step.
Max # of 
Iterations
Maximum number of iterations for the SAM.
The History tab only displays the values from a solve step. 
The values calculated during a Jacobian step can be seen on 
the Monitor tab of the adjust for the individual results.5-12
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ThTolerance
For the Adjust to converge, the error in the dependent variable 
must be less than the Tolerance.
It is sometimes a good idea to use a relatively loose (large) 
tolerance when initially attempting to solve an Adjust loop. Once 
you determine that everything is working properly, you can 
reset the tolerance to the final design value.   
Step Size
The step size you enter is used by the search algorithm to 
establish the maximum step size adjustment applied to the 
independent variable. This value is used until the solution has 
been bracketed, at which time a different convergence algorithm 
is applied. The value which is specified should be large enough 
to permit the solution area to be reached rapidly, but not so 
large as to result in an unreasonable overshoot into an infeasible 
region. 
A positive step size initially increments the independent 
variable, while a negative value initially decrements the 
independent variable. 
If the Adjust steps away from the solution, the direction of the 
steps are automatically reversed.
(5.1)
The tolerance and error values are absolute (with the same 
units as the dependent variable) rather than relative or 
percentage-type.
A negative initial step size causes the first step to decrement 
the independent variable.
Error Dependent Variable Value Target Value–=5-13
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5-14 Adjust
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ThMaximum/Minimum
These two optional criteria are the allowable upper and lower 
bounds for the independent variable. If either bound is 
encountered, the Adjust stops its search at that point.
Maximum Iterations
The default maximum number of iterations is 10. Should the 
Adjust reach this many iterations before converging, the 
calculations stop, and you are asked if you want to continue with 
more iterations. You can enter any value for the number of 
maximum iterations.
Options Page
The Options page contains two groups of settings:
• Secant Solver Options
• Generic Solver Options
The Secant Solver Options group offers the Relax Internal 
Bounds option as well as two settings: Bounds Tolerance and 
Relaxation Percentage.
If the secant solver takes a step and is above the target value, it 
sets the adjusted variable at that time as an internal maximum 
or minimum. However, HYSYS is not solving problems of the 
Before installing the Adjust module, it is often good practice 
to initialize the independent variable, and perform one 
adjust “manually”. Solve your flowsheet once, and notice the 
value for the dependent variable, then self-adjust the 
independent variable and re-solve the flowsheet. This 
assures you that one variable actually affects the other, and 
also gives you a feel for the step size you need to specify.
The Independent variable must be initialized (have a 
starting value) in order for the Adjust to work.5-14
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Thnature F(x)=y, but rather F(x) = G(x), so that the response 
surface changes as the adjusted variable changes. This can lead 
to a situation where we have an internal minimum and internal 
maximum set to the same value.
By using Relax Internal Bounds, you can allow these internal 
bounds to move out (within the specified minimum and 
maximum) if the adjusted variable is within the Bounds 
Tolerance of the local minimum or maximum. The bound can 
be relaxed by a Relaxation Percentage.
The Generic Solver Option group has one option that allows you 
to specify the solver to Always Stop At Maximum Iterations.
5.1.4 Monitor Tab
The Monitor tab contains the following pages:
• Tables
• Plots5-15
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ThTables Page
For each Iteration of the Adjust, the number, adjusted value, 
target value, and residual appear. If necessary, use the scroll 
bar to view iterations which are not currently visible. 
 Figure 5.8
You can also use the Solver Trace Window to view the 
Iteration History.
Iteration 
Number
Dependent 
(Target) 
Variable
Independent 
(Adjusted) Variable
Residual 
(Error)
Refer to Section 1.3 - 
Object Status & Trace 
Windows in the HYSYS 
User Guide for more 
information.5-16
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ThPlots Page
The Plots page displays the target and adjusted variables like on 
the Tables page, except the information is presented in graph 
form.
5.1.5 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
 Figure 5.9
Refer to Section 1.3.1 - 
Graph Control 
Property View for 
information on 
customizing plots.
For more information, 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-17
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5-18 Adjust
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Th5.1.6 Starting the Adjust
There are two ways to start the Adjust:
• If you have provided values for all the fields on the 
Parameters tab, the Adjust automatically begins its 
calculations.
• If you have omitted one or both values in the Minimum/
Maximum fields (on the Parameters tab) for the 
independent variable (which are optional parameters), 
and you would like the Adjust to start calculating, simply 
click the Start button.
The Start button then disappears, indicating the progress of the 
calculations. When the error is less than the tolerance, the 
status bar displays in green the “OK” message. If the Adjust 
reaches the maximum number of iterations without converging, 
the “Reached iteration Limit without converging” message 
appears in red on the status bar.
If you click the Start button when all of the required parameters 
are not defined, the status bar displays in yellow the 
“Incomplete” message, and calculations cannot begin.
Once calculations are underway, you can view the progress of 
the convergence process on the Iterations tab.     
With the exception of the minimum and maximum values of 
the independent (adjusted) variable, all parameters are 
required before the Adjust begins its calculations.
The Start button only appears in the initialization stage of 
the Adjust operation. It disappears from the property view 
as soon as it is pressed. Any changes made to the Adjust or 
other parts the flowsheet automatically triggers the Adjust 
calculation. 
To stop or disable the Adjust select the Ignored checkbox.5-18
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Th5.1.7 Individual Adjust
The Individual Adjust algorithm, either Secant or Broyden, uses 
a step-wise trial-and-error method, and displays values for the 
dependent and independent variables on each trial. The step 
size specified on the Parameters tab is used to increment, or 
decrement the independent variable for its initial step. The 
algorithm continues to use steps of this size until the solution is 
bracketed. At this point, depending on your choice, the 
algorithm uses either the Secant search (and its own step sizes) 
or Broyden search to quickly converge to the desired value. If a 
solution has not been reached in the maximum number of 
iterations, the routine pauses, and asks you whether another 
series of trials should be attempted. This is repeated until either 
a solution is reached, or you abandon the search. The Secant 
search algorithm generally results in good convergence once the 
solution has been bracketed.
5.1.8 Multiple Adjust
The term Multiple Adjust typically applies to the situation where 
all of the Adjusts are to be solved simultaneously. In this case, 
where the results of one Adjust directly affect the other(s), you 
can use the Simultaneous option to minimize the number of 
flowsheet iterations.
Examples where this feature is very valuable include calculating 
the flow distribution of pipeline looping networks, or in solving a 
complex network of UA-constrained heat exchangers. In these 
examples, you must select the stream parameters which HYSYS 
is to manipulate to meet the desired specifications. For a 
pipeline looping problem, the solution may be found by 
adjusting the flows in the branched streams until the correct 
pressures are achieved in the pipelines downstream. In any 
event, it is up to you to select the variables to adjust to solve 
your flowsheet problem.
HYSYS uses the modified Levenberg-Marquardt algorithm to 
simultaneously vary all of the adjustable parameters defined in 
the Adjusts until the desired specifications are met. The role of 
Refer to Chapter C2 - 
Synthesis Gas 
Production in the 
HYSYS Tutorials and 
Applications guide for 
an example using 
Multiple Adjusts.5-19
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5-20 Balance
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Thstep size with this method is quite different. With the single 
Adjust algorithm, step size is a fixed value used to successively 
adjust the independent variable until the solution has been 
bracketed. With the simultaneous algorithm, the step size for 
each variable serves as an upper limit for the adjustment of that 
variable.
In solving multiple UA exchangers, the starting point should not 
be one that contains a temperature crossover for one of the 
heat exchangers. If this occurs, a warning message appears 
informing you that a temperature crossover exists, and a very 
large UA value is computed for that heat exchanger. This value 
is insensitive to any initial change in the value of the adjustable 
variable, and therefore the matrix cannot be solved.
Install all Adjusts using the simultaneous option on the 
Parameters tab, then click the Start button to begin the 
calculations.
5.2 Balance
The Balance operation provides a general-purpose heat and 
material balance facility. The only information required by the 
Balance is the names of the streams entering and leaving the 
operation. For the General Balance, component ratios can also 
be specified.
Since HYSYS permits streams to enter or leave more than one 
operation, the Balance can be used in parallel with other units 
for overall material and energy balances. 
One requirement in implementing the Multiple Adjust feature 
is that you must start from a feasible solution.
The Balance overrides the filtering of streams that HYSYS 
typically performs.
Refer to Section 4.4 - 
Heat Exchanger for 
more information.5-20
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ThThe Balance Operation solves in both the forward and backward 
directions. For instance, it backs out the flowrate of an unknown 
feed, given that there are no degrees of freedom.
There are six Balance types which are defined in the table 
below: 
5.2.1 Balance Property View
There are two ways that you can add a Balance to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Balance.
Balance Type Definition
Mole An overall balance is performed where only the molar flow 
of each component is conserved. It can be used to provide 
material balance envelopes in the flowsheet, or to transfer 
the flow and composition of a process stream into a second 
stream.
Mass An overall balance is performed where only the mass flow is 
conserved. A common application would be for modeling 
reactors with no known stoichiometry, but for which 
analyses of all feeds and products are known.
Heat An overall balance is performed where only the heat flow is 
conserved. An application would be to provide the pure 
energy difference in a heat balance envelope.
Mole and 
Heat 
An overall balance is performed where the heat and molar 
flow are conserved. The most common application for this 
unit operation would be to perform overall material (molar 
basis) and energy balance calculations of selected process 
streams to either check for balances, or force HYSYS to 
calculate an unknown variable, such as flow. 
Most of the unit operations in HYSYS perform the 
equivalent of a Mole and Heat Balance besides their other 
more specialized calculations.
Mass and 
Heat
An overall balance is performed where the overall mass 
flow and heat flow are conserved.
General HYSYS solves a set of n unknowns in the n equations 
developed from the streams attached to the operation. 
Component ratios can be specified on a mole, mass or 
liquid volume basis.5-21
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5-22 Balance
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Th4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Balance icon. 
The Balance property view appears.
5.2.2 Connections Tab
The Connections tab is the same for all of the Balance Types.
 Figure 5.10
 Figure 5.11
Balance icon5-22
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ThThe tab contains the following pages:
• Connections
• Notes
Connections Page
On the Connections page, you must specify the following 
information:
• Name. The name of the balance operation.
• Inlet Streams. Attach the inlet streams to the balance.
• Outlet Streams. Enter the outlet streams to the balance 
operation. You can have an unlimited number of inlet and 
outlet streams. Use the scroll bar to view streams that 
are not visible.
5.2.3 Parameters Tab
The Parameters tab contains two groups:
• Balance Type
• Ratio List 
The Balance Type group contains a series of radio buttons, which 
allow you to choose the type of Balance you want to use. The 
radio buttons are:
• Mole
• Mass
 Figure 5.12
Refer to Section 1.3.5 - 
Notes Page/Tab for 
more information.5-23
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5-24 Balance
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Th• Heat
• Mole and Heat
• Mass and Heat
• General 
Mole Balance
This operation performs an overall mole balance on selected 
streams; no energy balance is made. It can be used to provide 
material balance envelopes in the flowsheet or to transfer the 
flow and composition of a process stream into a second stream.
• The composition does not need to be specified for all 
streams.
• The direction of flow of the unknown is of no 
consequence. HYSYS calculates the molar flow of a feed 
to the operation based on the known products, or vice 
versa.
• This operation does not pass pressure or temperature.
Mass Balance
This operation performs an overall balance where only the mass 
flow is conserved. An application is the modeling of reactors 
with no known stoichiometry, but for which analyses of all feeds 
and products are available. If you specify the composition of all 
streams, and the flowrate for all but one of the attached 
streams, the Mass Balance operation determines the flowrate of 
the unknown stream. This is a common application in alkylation 
units, hydrotreaters, and other non-stoichiometric reactors.
• The composition must be specified for all streams.
• The flowrate must be specified for all but one of the 
streams. HYSYS determines the flow of that stream by a 
mass balance.
• Energy, moles, and chemical species are not conserved. 
The Mass Balance operation determines the equivalent 
masses of the components you have defined for the inlet 
and outlet streams of the operation.
• This operation does not pass pressure or temperature.
The Ratio List group applies only to the General balance. This 
is discussed in the General Balance section.5-24
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ThHeat Balance
This operation performs an overall heat balance on selected 
streams. It can be used to provide heat balance envelopes in the 
flowsheet or to transfer the enthalpy of a process stream into a 
second energy stream.
• The composition and material flowrate must be specified 
for all material streams. The heat flow is not passed to 
streams which do not have the composition and material 
flowrate specified, even if there is only one unknown 
heat flow.
• The direction of flow for the unknown stream is of no 
consequence. HYSYS calculates the heat flow of a feed to 
the operation based on the known products, or vice 
versa.
• This operation does not pass the pressure or 
temperature.
• You cannot balance the heat into a Material Stream.
Mole and Heat Balance
The most common application for this balance is to perform 
overall material (molar basis), and energy balance calculations 
of selected process streams to either check for balances or force 
HYSYS to calculate an unknown variable, such as a flowrate.
• The Mole and Heat Balance independently balance 
energy and material.
• The Mole and Heat Balance calculate ONE unknown 
based on a total energy balance, and ONE unknown 
based on a total material balance.
• The operation is not directionally dependent for its 
calculations. Information can be determined about either 
a feed or product stream.
• The balance remains a part of your flowsheet and as 
such defines a constraint; whenever any change is made, 
the streams attached to the balance always balances 
with regard to material and energy. As such, this 
constraint reduces by one the number of variables 
available for specification.
• Since the Mole and Heat Balance work on a molar basis, 
it should not be used in conjunction with a reactor where 
chemical species are changing.5-25
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5-26 Balance
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ThMass and Heat Balance
Similar to the Mass balance mode, this balance mode performs a 
balance on the overall mass flow. In addition, however, energy is 
also conserved.
• The composition must be specified for all streams.
• Flow rate must be specified for all but one of the 
streams. HYSYS determines the flow of that stream by a 
mass balance.
• Enthalpy must be specified for all but one of the streams. 
HYSYS determines the enthalpy of that stream by a heat 
balance.
• Moles and chemical species are not conserved.
General Balance
The General Balance is capable of solving a greater scope of 
problems. It solves a set of n unknowns in the n equations 
developed from the streams attached to the operation. This 
operation, because of the method of solution, is extremely 
powerful in the types of problems that it can solve. Not only can 
it solve unknown flows and compositions in the attached 
streams (either inlet or outlet can have unknowns), but ratios 
can be established between components in streams. When the 
operation determines the solution, the prescribed ratio between 
components are maintained.
• The General balance solves material and energy balances 
independently. An Energy Stream is an acceptable inlet 
or outlet stream.
• The operation solves unknown flows or compositions, 
and can have ratios specified between components in 
one of the streams.
• Ratios can be specified on a mole, mass or liquid volume 
basis.
Ratios
A Ratio, which is unique to the general Balance, is defined 
between two components in one of the attached streams. 
Multiple ratios within a stream (for example 1:2 and 1:1.5) can 
be set with a single Ratio on a mole, mass or liquid volume 5-26
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Thbasis. Each individual ratio (1:2, 1:1, and 1:1.5), however uses 
a degree of freedom.
To set a ratio:
1. On the Parameters tab of the Balance operation property 
view, select the General Balance radio button. 
The Ratio List group should now be visible.
2. Click the Add Ratio button to access the Ratio property 
view.
3. In the Ratio property view, specify the following information:
• Name. The name of the Ratio.
• Stream. The name of the stream.
• Ratio Type. Allows you to specify the Ratio Type: Mole, 
Mass, or Volume.
• Component/Ratio. Provides the relative compositions 
of two or more components. Other components in the 
stream are calculated accordingly, and it is not necessary 
nor advantageous to include these in the table. All ratios 
must be positive; non-integer values are acceptable.
 Figure 5.13
 Figure 5.14
To view a specific ratio, 
select the ratio in the 
Ratio List group and click 
the View Ratio button.
To delete a ratio, 
open the Ratio 
property view of 
the component 
ratio, and then 
click the Delete 
button in that 
Ratio property 
view.5-27
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5-28 Balance
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ThNumber of Unknowns
The general Balance determines the maximum number of 
equations, and hence unknowns, in the following manner (notice 
that the material and energy balances are solved 
independently):
• One equation performing an overall molar flow balance.
• {Number of Components (nc)} equations performing an 
individual molar balance.
• {Number of Streams (ns)} equations, each performing a 
summation of individual component fractions on a 
stream by stream basis.
This is the maximum number of equations (1 + nc + ns), and 
hence unknowns, which can be solved for a system. When ratios 
are specified, they reduce the available number of unknowns. 
For each ratio, the number of unknowns used is one less than 
the number of components in the ratio. For example, for a 
three-component ratio, two unknowns are used.
5.2.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
5.2.5 Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
5.2.6 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-28
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Th5.3 Boolean Operations
The Boolean Logic block is a logical operation, which takes in a 
specified number of boolean inputs and then applies the boolean 
operation to calculate an output. A typical use of the Boolean 
Logic is to apply emergency shutdown of an exothermic reactor, 
such as closing the valves on the fuel and air line to the reactor 
when the reactor core temperature exceeds its setpoint. It is 
also used to simulate the ladder diagrams, which are found in 
most of the electrical applications.
The following Boolean Logic blocks are available in HYSYS:
• And Gate
• Or Gate
• Not Gate
• Xor Gate
• On Delay Gate
• Off Delay Gate
• Latch Gate
• Counter Up Gate
• Counter Down Gate
• Cause And Effect Matrix    
To evaluate the Boolean Logic blocks at each time step, open 
the Integrator property view and go to the Execution tab. In 
the Calculation Execution Rates group, change the Control 
and Logical Ops field value to 1. 
This change ensures that your time sensitive Boolean Logic 
blocks like On Delay and Off Delay are executed at the 
required time instead of a one time step delay. This change 
also slows down the HYSYS calculation rate and is noticeable 
for large cases.
For more information 
about the Integrator 
property view, refer to 
Section 7.7 - 
Integrator in the HYSYS 
User Guide.5-29
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Th5.3.1 Boolean Logic Blocks 
Property View
There are two ways that you can add Boolean Logic Blocks to 
your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select the Boolean 
Logic that you want.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Click on the Boolean Ops icon. The Boolean Palette 
appears.
 Figure 5.15
Boolean 
Ops icon5-30
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Logical Operations 5-31
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Th3. Double-click the icon of the Boolean Logic that you want. 
The selected Boolean Logic property view appears.
The property view for all the Boolean Logic blocks in HYSYS 
contains four tabs (Connections, Monitor, Stripchart, and User 
Variables), a Delete button, and a Face Plate button. 
Boolean Logic Icon Boolean Logic Icon 
Not Gate On Delay Gate
And Gate Latch Gate
Or Gate Counter Up Gate
Xor Gate Counter Down 
Gate
Off Delay Gate Cause And Effect 
Matrix
 Figure 5.165-31
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5-32 Boolean Operations
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ThLogical Operation Face Plate Property View
The Face Plate button enables you to access the Face Plate 
property view. The Face Plate property view allows you to see 
the Boolean type and output value at a glance. 
On the PFD property view, the digital/boolean and boolean/
boolean logical connections have the capability to display the 
change of logical state by changing the line colour to either 
green (1) or red (0). 
The output is set up to have a default initial value of 1 for all the 
Boolean Logic blocks.
Connections Tab
The Connections tab is where you connect operations to the 
Boolean Logic block. Boolean unit operations can make logical 
connections with Digital Point, as well as, among themselves. 
The connections can either be made from the Connections tab, 
or through the PFD. 
If the Boolean type supports multiple process variable sources, 
the Process Variable Sources group contains a table with three 
buttons with the same functions as the buttons in the Output 
Target group. 
 Figure 5.17
 Figure 5.18
Click on the Setup button 
to open the Boolean Logic 
property view.
This field displays the 
Boolean Logic type.
This field displays the output 
value.
OP = 0
OP = 15-32
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Logical Operations 5-33
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ThThe figure below displays the Connections tab of a Boolean Not 
Gate operation. 
Adding/Editing Process Variable Source
Depending on the Boolean type, you have to click the Select PV 
button, the Edit PV button or the Add PV button to open the 
Select Input PV property view. 
 Figure 5.19
 Figure 5.20
The Select Input PV property view is similar to the Variable 
Navigator property view. 
The type of Boolean 
Logic block is shown 
in this display field. 
Edit OP button allows 
you to change the 
selected output 
connection.
Add OP button allows 
you to add an output 
connection.
Delete OP button 
allows you to delete 
the selected output 
connection.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information on.5-33
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5-34 Boolean Operations
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ThAdding/Editing Output Target
Click the Edit OP button or Add OP button to open the Select 
Output PV property view.
Use the radio button in the Object Filter group to filter the 
Object list to the operations you want.
Monitor Tab
The Monitor tab allows you to monitor the input and output 
values of the Boolean Logic block. The contents of this tab varies 
from one Boolean Logic type to another. For example, the 
Monitor tab of an On Delay Gate boolean also contains a field 
where you can specify the time delay.
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
 Figure 5.21
Select the operation to 
receive the output value from 
the list, then click the OK 
button.
Click the Disconnect button 
to disconnect the connection 
in the property view.
Click the Cancel button to exit 
the property view without 
changing anything.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-34
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Logical Operations 5-35
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Th5.3.2 And Gate
This unit operation performs a logical AND function on a set of 
inputs. The output is always low as long as any one of the input 
is low and it is high when all of the inputs are high. The table 
below displays the function logic for the And Gate. 
The Monitor tab of the And Gate displays the following 
information:
• Input. Contains the name and number used to designate 
the input connection.
• Object. Displays the operation name of the input 
connection.
• Initial State. Displays the input value received by the 
Boolean Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the Boolean type and the input 
values from the input connections.     
Input 1 Input 2 Input 3 Output
1 1 1 1
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 0
The And Boolean Logic block can have any number of inputs 
and a single output, which can be fanned out.
The input and output values can only be 1 or 0.
 Figure 5.225-35
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5-36 Boolean Operations
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Th5.3.3 Or Gate
This unit operation performs a logical OR function on a set of 
inputs. The output is always high as long as any one of the input 
is high and it is low when all of the inputs are low. The table 
below displays the function logic for the Or Gate. 
The Monitor tab of the Or Gate displays the same information as 
the And Gate.
Input 1 Input 2 Input 3 Output
1 1 1 1
1 0 0 1
0 1 0 1
0 0 1 1
0 0 0 0
The Or Boolean Logic block can have any number of inputs 
and a single output, which can be fanned out.
The input and output values can only be 1 or 0.
 Figure 5.235-36
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Logical Operations 5-37
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Th5.3.4 Not Gate
This unit operation perform a logical NOT function on an input. 
The output is the negative of the input. In other words, when 
the input is high the output is low and vice versa. The table 
below displays the function logic for the Not Gate. 
The Monitor tab of the Not Gate displays the following 
information:
• Input Value. Displays the value received by the Boolean 
Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the input value from the input 
connection. 
Input Output
1 0
0 1
The input and output values can only be 1 or 0.
The output in this unit operation can also be fanned out.
 Figure 5.245-37
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5-38 Boolean Operations
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Th5.3.5 Xor Gate
This unit operation performs an exclusive or function on two 
inputs. The output state is always High (1) whenever anyone of 
the input is high (1), but it is low (0) when all of the inputs are 
high (1). The table below displays the function logic for Xor 
Gate. 
The Monitor tab of the Xor Gate displays the following 
information:
• Input. Contains the name and number used to designate 
the input connection.
• Object. Displays the operation name of the input 
connection.
• Initial State. Displays the input value received by the 
Boolean Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the Boolean type and the input 
values from the input connections.
Input 1 Input 2 Output
1 1 0
1 0 1
0 1 1
0 0 0
The input and output values can only be 1 or 0.
This unit operation can only have two input connections.
The output in this unit operation can also be fanned out.
 Figure 5.255-38
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Logical Operations 5-39
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Th5.3.6 On Delay Gate
This unit operation performs an on time delay function on a 
single input. The output’s signal is delayed for a specified time 
delay ( ) only when the input is set to be 1. The following 
logical expression is used to calculate the output (y) for an input 
(x) change. 
The Monitor tab of the On Delay Gate displays the following 
information:
• Delay Time. Allows you to specify the amount of time 
you want for the time delay function. The default value is 
10 minutes.
• Input Value. Displays the value received by the Boolean 
Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the input value from the input 
connection.
For x = 1,
(5.2)
The input and output values can only be 1 or 0.
The output in this unit operation can also be fanned out.
 Figure 5.26
θ
y t( ) 0 t θ<
1 t θ≥⎩
⎨
⎧
=
5-39
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5-40 Boolean Operations
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Th5.3.7 Off Delay Gate
This unit operation performs an off time delay function on a 
single input. The output’s signal is delayed for a specified time 
delay ( ) only when the input is set to be 0. The following 
logical expression is used to calculate the output (y) for an input 
(x) change.
The Monitor tab of the Off Delay Gate displays the following 
information:
• Delay Time. Allows you to specify the amount of time 
you want for the time delay function. The default value is 
10 minutes.
• Input Value. Displays the value received by the Boolean 
Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the input value from the input 
connection.
For x = 0,
(5.3)
The input and output values can only be 1 or 0.
The output in this unit operation can also be fanned out.
 Figure 5.27
θ
y t( ) 1 t θ<
0 t θ≥⎩
⎨
⎧
=
5-40
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Logical Operations 5-41
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Th5.3.8 Latch Gate
This unit operation provides a latch functionality. It requires two 
input signals; one for set and other one for reset. The second 
input is the prevailing input meaning that it specify the output to 
be set to high (1), reset to low (0), or left unchanged. The table 
below displays the function logic for the Latch Gate. 
The Monitor tab of the Latch Gate displays the following 
information:
• Prevailing Input. The radio buttons come into play 
when both of the inputs are high(1). It allows you to 
specify what you want the output value to be. Selecting 
Set makes the OP value to be high(1), and Reset makes 
it low(0).
• Input. Contains the name and number used to designate 
the input connection.
• Object. Displays the operation name of the input 
connection.
• Initial State. Displays the input value received by the 
Boolean Logic block.
Input 1 Input 2 Output
1 1 override state
1 0 1
0 1 0
0 0 previous state
By definition the latch gate allows you to select the OP value 
when both of its inputs are high. So this state is known in the 
industry as override state.
The input and output values can only be 1 or 0.
This unit operation can only have two input connections.
The output in this unit operation can also be fanned out.5-41
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5-42 Boolean Operations
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Th• Output Value. Displays the output value of the Boolean 
Logic block, based on the input value from the input 
connection.
5.3.9 Counter Up Gate
This unit operation acts as an up counter. It counts up to a 
maximum counter value which is specified by the users. It is 
triggered everytime the input is switched to a desired state. 
After reaching the maximum counter limit, it sets the output to 
a predefined value. The counter and output value is reset with 
the second input by switching it to high (1).
The Monitor tab of the Counter Up Gate displays the following 
information:
• Maximum Counter. Allows you to specify the counter 
limit value. The default value is 10.
• Current Counter. Displays the current counter value.
• PV Alarm. Allows you to select which PV value triggers 
the counter to increase a step. You can only choose 0 or 
1.
• Desired Output Value. Allows you to select what the 
output value should be when the counter reaches 
maximum. You can only choose 0 or 1.
• Input. Contains the name and number used to designate 
the input connection.
• Object. Displays the operation name of the input 
connection.
 Figure 5.28
The input and output values can only be 1 or 0.
The output in this unit operation can also be fanned out.5-42
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Logical Operations 5-43
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Th• Initial State. Displays the input value received by the 
Boolean Logic block.
• Output Value. This field displays the output value of the 
Boolean Logic block, based on the input value from the 
input connection.
5.3.10 Counter Down Gate
This unit operation acts as a down counter. It counts down to a 
maximum counter value which is specified by the users. It is 
triggered everytime the input 1 is switched to a desired state. 
After the counter has reached zero, it sets the output to a 
predefined value. The counter and output value is reset with the 
second input by switching it to High (1). 
The Monitor tab of the Counter Down Gate displays the following 
information:
• Maximum Counter. Allows you to specify the counter 
limit value. The default value is 10.
• Current Counter. Displays the current counter value.
• PV Alarm. Allows you to select which PV value triggers 
the counter to decrease a step. You can only choose 0 or 
1.
• Desired Output Value. Allows you to select what the 
output value should be when the counter reaches 0. You 
can only choose 0 or 1.
 Figure 5.295-43
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5-44 Boolean Operations
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Th• Input. Contains the name and number used to designate 
the input connection.
• Object. Displays the operation name of the input 
connection.
• Initial State. Displays the input value received by the 
Boolean Logic block.
• Output Value. Displays the output value of the Boolean 
Logic block, based on the input value from the input 
connection.  
5.3.11 Cause and Effect Matrix
This unit operation replicates a Cause and Effect matrix 
commonly used in designing and operating the safety system of 
many processing plants. It looks at process values throughout 
the process and, based upon safety thresholds, determines if 
certain equipment and/or valves should be shutdown.
The unit operation is similar to a spreadsheet. It takes inputs 
called Causes, and sends outputs called Effects. 
The input may be any simulation variable from the users case or 
a simple switch which is not required to be connected to an 
object’s variable. Each input generates either a Healthy (1) or 
Tripped (0) state. 
The input and output values can only be 1 or 0.
The output in this unit operation can also be fanned out.
 Figure 5.30
Refer to Section 5.10 - 
Spreadsheet for more 
information on the 
spreadsheet.5-44
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Logical Operations 5-45
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ThThe output is a boolean (1 or 0) result from processing one of 
the Cause and Effect Matrix columns. The output may write or 
export its result to any simulation variable within the users case. 
The user must specify a variable of discrete type (1 or 0). The 
output is not required to be connected to an object or variable. 
The same 1 or 0 result is produced from the matrix column, and 
then any other object in the simulation may read or use this 
value.
The matrix is processed one column at a time to determine the 
resultant state of the output associated with that column. The 
associated input state is reviewed for each element (or row 
entry) of a particular column having a non-blank user specified 
matrix element. All of the matrix elements of that column (and 
their associated input state) are compared based upon their 
respective and collective meaning to determine the Cause 
result.
The boolean inputs enter through logical gate type operations 
(and, or, not, and so forth) with each other to determine the 
resultant boolean value. 
It is important that you clarify the 1 and 0 convention of the 
Cause and Effect Matrix for Healthy/Tripped, On/Off, Start/
Stop, and so forth.
For both the inputs and outputs, a result of 0 indicates 
Tripped, whereas a result of 1 indicates Healthy, except 
where the Invert checkbox is turned on. 
When the Invert checkbox is turned on, a result of 0 
indicates Healthy, whereas a result of 1 indicates Tripped.
You can access the Cause and Effect Matrix help property 
view by clicking on the Cause and Effect Help button on the 
C&E Matrix tab.5-45
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5-46 Boolean Operations
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ThEach matrix element type is described in the following table. 
Configuring a Cause and Effect 
Matrix
There are no PFD streams or lines that connect to or from the 
Cause and Effect Matrix operation. Hence you can place it 
anywhere and on any flowsheet. You can also view all simulation 
variables across flowsheets, the same as with a Spreadsheet.
Matrix Elements Description
X TRIP One or more zero input(s) causes a zero output.
R RESET One or more 1 inputs causes a 1 output (as long as there are no X, T 
or C active and ALL P must be 1)
There is no requirement to have a reset on a particular output. If 
you want a reset, this can either be done with one or more R matrix 
element entries or a local reset switch. In the case of both R and a 
local reset, then both reset features must be reset for the output to 
return to normal, and the local reset must be done last.
T TIMED TRIP Same as the TRIP but the input must have remained zero for at least 
the time period.
The T matrix element should be followed by an integer representing 
the number of seconds of time delayed trip.
C COINCIDENT 
TRIP
In contrast to all other trips, a zero input for ALL the coincident 
signals of the same grouping causes a zero output.
The C matrix element should be followed by an integer representing 
the Coincident group number. There should be more than one in 
each group.
P PERMISSIVE All P inputs must be 1 to permit an R to have the desired effect. Also 
required for a STANDBY 1 effect, a local reset and a local switch ON.
I INHIBIT A 1 will inhibit any trip of the output which would normally be 
caused by an X,T or C.
S STANDBY A 1 will cause a 1 (as long as there are no X, T or C active and ALL P 
must be 1), and a zero will cause a zero output (no INHIBIT 
applicable).
Normally one would not want more than one Standby input 
designation per output. If you have more than one Standby, ALL 
Standby inputs must have a 1 for the output to be started (1 result). 
Otherwise, a zero output result is produced. All Permissive inputs 
must be 1 for the Standby 1 action to occur. 
It is recommended that you build a dynamics case first with 
all the specifications in place before adding and configuring 
a Cause and Effect Matrix.
Refer to Section 5.10 - 
Spreadsheet for more 
information on the 
spreadsheet.5-46
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Logical Operations 5-47
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ThTo add a new Cause and Effect Matrix unit operation to the 
flowsheet, refer to Section 5.3.1 - Boolean Logic Blocks 
Property View. 
You can set the global defaults and controls on the Parameters 
tab as shown in steps below:
1. You can specify the global defaults by clicking on the 
appropriate checkboxes.  
2. You can specify the global control by clicking on the 
appropriate checkboxes.   
 Figure 5.31
Checkbox Description
Input Invert Allows you to set the invert checkbox on for all new 
inputs.
Output Invert Allows you to set the invert checkbox on for all new 
outputs.
Hand Switch 
Pulse Duration
You can specify the pulse duration for any hand Switch 
inputs that are pulsed.
Always Update 
Output Objects
You can select this checkbox, if you want to ensure 
that the results from the logic calculations are sent 
every timestep to the output objects.
Use Output 
Resets
Select this checkbox if you want the Use Reset 
checkbox selected for all new outputs.
Use Local 
Switches for 
Outputs
You can select this checkbox, if you want the Use 
Local Switch checkbox selected for all new outputs.
Insert New 
Above/To Left
When you add a new row or column and this checkbox 
is selected, the row or column will be added above (to 
the left) of that currently selected row or column.
 Figure 5.325-47
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5-48 Boolean Operations
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ThYou can view all the input and output configuration information 
on the Parameters tab. 
Checkbox Description
Reset All Outputs If you want to reset all individual outputs, select this 
checkbox.
Bypass All 
Outputs
When you select this checkbox, the Bypass checkbox 
of each output is turned on. 
Trace Alarms & 
Trips
If you want to trace the occurrence of input alarms, 
input trips and output trips, select this checkbox.
The Trace Alarms & Trips checkbox affects ALL Cause 
and Effect matrix instances in your model.
 Figure 5.335-48
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Logical Operations 5-49
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ThConnecting the Inputs
1. On the Connections tab or the C&E Matrix tab, click the 
Add Input button to add and connect an input. The 
Simulation Navigator appears.
2. From the Simulation Navigator, select the input variable. 
Then click OK.
By default, the new input is added at the bottom of any 
existing inputs.
From the Parameters tab, select the Insert New Above/To 
Left checkbox, now the new input is added above the 
currently selected row. You have to select the bottom blank 
input row to add to the bottom of the existing inputs.
3. Alternatively, If you want to add switch inputs, click the Add 
Switch button on the C&E matrix tab. A new input row is 
added, but no simulation variable needs to be selected. The 
user can manually change the switch during the operation of 
the dynamic model.
A switch input is useful for a R(eset) matrix element entry. 
You should make this a Pulse On type switch. Switches can 
also be useful as an emergency shutdown pushbutton if you 
want to test your dynamic model response to the trip of a 
collection of outputs. 
You can change the state of the switch by clicking on the 
appropriate radio buttons.
 Figure 5.345-49
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5-50 Boolean Operations
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Th   
4. Enter the description, tag, and comment (if any) for the 
Inputs (Causes). The description appears to the left of each 
input row, and its associated matrix elements on the C&E 
Matrix tab.
5. For all inputs with a simulation variable (not a switch), 
except for the Digital Point’s OP State or an output result 
from a Cause and Effect matrix, specify the trip threshold. 
Select the High? checkbox if a value higher than the 
threshold will result in a tripped input. Otherwise, a low 
threshold trip is assumed.
You can also specify an Alarm threshold, which acts as a pre-
alarm prior to the trip actually occurring.
Click the Invert checkbox, if you want to invert the meaning 
of the matrix elements. 
6. You can also override the effect of any tripped inputs by 
clicking on the OR (Override) checkbox in the Inputs 
(Causes) table on the C&E Matrix tab or the Inputs 
(Causes) group on the Parameters tab. You can use this as 
a startup override.
If a trip requires a reset, you will have to activate the input(s), 
which resets it or you may have to reset the local reset. 
 Figure 5.35
In the Inputs (Causes) table, click on a row with the SW 
checkbox selected. 
The input can also be a time delayed Trip resulting to zero by 
entering a non-zero time in the Off Delay field.
The inversion (1 to 0 or 0 to 1) occurs at the completion of 
the normal input processing just before the input result is 
passed on for matrix processing. Hence the input status, 
trace messages, and so forth, occur as normal irregardless of 
inversion.
For more information on 
viewing the specifications 
for the inputs and 
outputs, refer to the 
section on Viewing the 
Inputs and Outputs 
Specifications.5-50
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Logical Operations 5-51
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ThConnecting the Outputs
1. In the Outputs (Effects) group, click the Add Output button 
to create a new Cause and Effect Matrix column. Specify the 
simulation variable that you want the resultant 1 or 0 
exported to.
By default, the new output is added to the right (end) of any 
existing outputs. From the Parameters tab, select the 
Insert New Above/To Left checkbox, and now the new 
output is added to the left of the currently selected column. 
You can select the last blank output column to add to the 
right of the existing outputs.
2. If you want to add a new column without connecting an 
object’s variable, click the Add Effect button in the Outputs 
(Effects) group.
3. Select the Reset? checkbox if you want to specify the output 
has its own local reset switch. This could perhaps represent 
a solenoid on a shutdown valve in the field. Once the Reset? 
checkbox is selected, then the Reset checkbox becomes 
active and relevant.     
You can add a new column without connecting a simulation 
variable, if you want to just display a trip.
You can also access the outputs result using the input in 
other logical operations including other Cause and Effect 
Matrices or using a Spreadsheet Import. Use the Simulation 
Navigator from that unit operation to select the Cause and 
Effect Matrix Output Result.
It is not recommended to configure an output without a 
reset. This can be a matrix element R(eset) or a local reset.5-51
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5-52 Boolean Operations
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Th4. You can also specify the presence of a local or field switch for 
the controlled equipment that the output is associated with. 
To specify the presence, select the SW (Switch) checkbox. 
Click on the appropriate radio button to set the local switch 
state. 
5. You can click the Invert checkbox in the Outputs (Effects) 
group if the object being controlled expects a 1 to shutdown 
rather than a zero. This output inversion is done at the 
completion of the output processing, therefore the Outputs 
(Effects) group status bar and property view status window 
will show a Tripped status when sending a 1. If the trace 
option is turned on, a Tripped message will be traced, but a 
final value of 1 will be sent out.
6. Once you have your Cause and Effect Matrix configured, you 
may want to use the Bypass checkbox of some or all 
outputs. This then makes the resultant value in the Outputs 
(Effects) group at the bottom of the C&E Matrix tab turn 
blue. This value should initialize to 1 and will remain at this 
until the bypass is released and matrix output processing 
proceeds. You can bumplessly prevent initialization trips in 
this manner.
 Figure 5.36
This switch has as its permissive any inputs with a P matrix 
element. Also, the switch is interlocked with any inputs 
affecting a trip of this output. 
An output must be reset before the local switch state can be 
changed from off.
When a certain input trips, causing a resulting trip in an 
output, there is also likely to be a cascading set of trips 
including other inputs which may appear to cause a trip of 
the original output. To detect what was the first input to 
cause the output's trip, you will see the relevant first out 
matrix element which caused the trip turn red. This colour 
only returns to the default of blue when the output trip has 
cleared and been reset.5-52
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Logical Operations 5-53
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ThChanging the order of the inputs or 
outputs
If the inputs or outputs are not in the order that you want, you 
can re-sort either the rows or columns of the Cause and Effect 
Matrix:
1. From the Inputs (Causes) or Outputs (Effects) tables of the 
C&E Matrix tab, select the row or column you want to 
move.
2. In the Inputs (Causes) or Outputs (Effects) groups, click 
on the row or column number displayed in the # field. 
3. Type the new number that you want the row or column to be 
located at. 
If you type a number that is smaller than the number of the 
row (or column) you are moving, all rows (or columns) 
below the new number will be moved down (to the right) 
hence filling in the empty row (or column). Alternatively, if 
the new number is greater than the number of the row (or 
column) you are moving, the rows (or columns) will be 
moved up (to the left).
The row or column number is displayed in blue indicating 
that the user can change the value.5-53
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ThViewing the Inputs and Outputs 
Specifications
You can view all the specifications for the inputs and outputs on 
the C&E Matrix tab. 
 Figure 5.37
If you want to view the specifications for the Output:
1. On the C&E Matrix tab, select the column of the Effect data in the Outputs 
table.
2. The information for that output is shown in the Outputs group at the bottom 
of the tab.
When you click on 
the matrix 
element, the 
specifications for 
the selected row 
and column are 
shown in the 
Inputs and Outputs 
groups at the 
bottom of the tab.
If you want to 
view the 
specifications for 
the Input:
1. On the C&E 
Matrix tab, 
select the row 
of the Cause 
data in the 
Inputs table.
2. The information 
for that input is 
shown in the 
Inputs group at 
the bottom of 
the tab.
Inputs (Causes) group
Outputs (Effects) group
You can drag and drop input or output object/variables to the object or variable columns of the 
selected row or column in the Inputs (Causes) or Outputs (Effects) groups. Select the variable from 
some other unit operation, and then use the right mouse button to drag the selection to the desired 
location. 
When you drag the variable the pointer changes to this cursor .
This functionality is similar to dragging the variable in the Spreadsheet, refer to Section 5.10 - 
Spreadsheet.5-54
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ThThe C&E Matrix tab also shows the state of each input and 
output.
Viewing the Status Messages
While integrating, the status window and the Cause and Effect 
Matrix's status bar may update to show the following three 
states: 
1. one or more outputs have tripped
2. one or more inputs are in alarm
3. one or more outputs require reset (either via an input with 
an R matrix element or via a local output reset). 
The status of the inputs and outputs is shown in the table 
below:
State Description
Healthy (1 result)
Tripped (0 result)
For an input this means alarm.
For an output this indicates some other state. Refer to the 
Output status at the bottom of the property view for an 
indication of the exact status.
For both inputs and outputs, this indicates that attention is most 
likely required.
State Inputs Outputs
Healthy 1 1
Alarm 2
Tripped 0 0
Reset 2
LocalReset 3
ManualOff 4
AutoOff 55-55
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ThViewing Trace Messages
You can also add a time stamp to the trace messages.
1. From the Tools menu, select Preferences. The Session 
Preferences property view appears.
2. On the Simulation tab, click on the Errors page.
3. Click on the Prefix Integrator Time to Error ad Trace 
Messages if Dynamics is Running checkbox to add the 
time stamp to the trace messages, and close the Session 
Preferences property view.
The Cause and Effect Matrix tracing is turned on by selecting 
the Trace & Alarms checkbox on the Global group of the 
Parameters tab.
 Figure 5.385-56
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Th5.4 Control Ops
HYSYS has four Control operations:
• Split Range Controller
• Ratio Controller
• PID Controller
• MPC Controller
• DMCplus Controller
5.4.1 Adding Control 
Operations
There are two ways that you can add Control Operations to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select the Control 
operation you want.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.5-57
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Th2. Click on the Control Ops icon. The Controller Palette 
appears.
3. Double-click the icon of the Control operation that you want.
The selected Control operations property view appears.
 Figure 5.39
Control Operation Icon Control Operation Icon
Split Range 
Controller
MPC Controller
Ratio Controller DMCplus Controller
PID Controller
 Figure 5.40
Control Ops 
icon5-58
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ThAll Control operations contain the following buttons at the 
bottom of the property view:
• Delete. You can remove the Control ops by clicking this 
button. 
• Face Plate. You can access the Face Plate property view 
by clicking this button.
• Control Valve. You can access the Control Valve 
property view by clicking this button.
or
• Control OP Port. You can access the Control OP Port 
property view by clicking this button.
5.4.2 Split Range Controller
In the Split Range Controller, several manipulated variables are 
used to control a single process variable. Here both manipulated 
variables are driven by the output of a single controller. 
However, the range of operation for the manipulated variables 
can be independent of each other. Typical examples include the 
control of the pressure in a chemical reactor by manipulating the 
inflow and outflow from the reactor. 
Another classic example is the temperature control of a vessel 
by manipulating both the cooling water flow and steam flow to 
the vessel.
When there is more than one controller in the strategy, for 
example, one single process variable with two controllers and 
two manipulated variables, the control is referred to as a 
multiple controller strategy.
In the present implementation in HYSYS there are two outputs 
that you have to choose. The outputs can be configured as 
having negative or positive gains with ranges that are 
independent of each other. In other words, there can be an 
overlap of the ranges.
For more information 
refer to Section 5.13.2 - 
Controller Face Plate.
For more information 
refer to Section 5.4.7 - 
Control Valve.
For more information 
refer to Section 5.4.8 - 
Control OP Port.5-59
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ThThe figure below shows the Split Range Controller property 
view.
The Split Range Controller property view contains the following 
tabs:
• Connections
• Parameters
• Split Range Setup
• Stripchart
• User Variables
 Figure 5.415-60
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ThConnections Tab
On the Connections tab, you can select the process variable 
source and the output target objects.  
 Figure 5.42
Object Description
Name field Allows you to change the name of the operation.
Process Variable 
Source group
• Select PV button enables you to access the 
Select Input PV property view and select the 
source object of the Process Variable.
• Object field displays the Process Variable object 
(stream or operation) that owns the variable you 
want to compare.
• Variable field displays the variable of the 
selected object.
Output Target 
Object group
• Select OP button enables you to access the 
Select OP Object property view and select the 
source object of the Output Target.
• Object field displays the object (stream or 
operation) that is controlled by the operation.
• Variable field displays the variable of the 
selected object.
Remote Setpoint 
group
• Select RSP button enables you to access the 
Select Remote Setpoint property view and select 
the source object of the Remote Setpoint.
• Remote Setpoint field displays the selected 
master controller.
Click the up and 
down arrows to 
access the first and 
second variables.
If you are using set 
point from a remote 
source, select the 
remote Setpoint 
Source associated 
with the Master 
controller.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information Select Input 
PV and Select OP Object 
property view.5-61
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ThParameters Tab
The Parameters tab contains the following pages:
• Operation
• Configuration
• Advanced
• Autotuning
• IMC Design
• Scheduling
• Alarms
• Signal Processing
• Initialization
Operation Page
On the Operation page, you can manipulate how the operation 
reacts to the process variable inputs.
 Figure 5.435-62
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ThObject Description
Action You can select one of the two types of action available for 
the operation to take when the process variable value 
deviates from the setpoint value:
• Direct. When the PV rises above the SP, the OP 
increases. When the PV falls below the SP, the OP 
decreases.
• Reverse. When the PV rises above the SP, the OP 
decreases. When the PV falls below the SP, the OP 
increases.
Controller 
Mode
You can select from three types of controller mode:
• Off. The operation does not manipulate the control 
valve, although the appropriate information is still 
tracked.
• Manual. Manipulate the operation output manually.
• Automatic. The operation reacts to fluctuations in the 
Process Variable and manipulates the Output 
according to the logic defined by the tuning 
parameters.
Execution You can select from two types of execution.
• Internal. Confines the signals generated to stay 
within HYSYS.
• External. Sends the signals to a DCS, if a DCS is 
connected to HYSYS.
Sp Allows you to specify the setpoint value.
Pv Displays the process variable value.
Op Displays the output value.
Split Range 
Output
Displays the current OP value in percent for each output.
Kc (Gain) Allows you to specify the proportional gain of the operation. 
Ti (Reset) Allows you to specify the integral (reset) time of the 
operation. 
Td 
(Derivative)
Allows you to specify the derivative (rate) time of the 
operation. 
Refer to Tuning 
Parameters Group 
section for more 
information on Kc, Ti, and 
Td.5-63
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ThTuning Parameters Group
The Tuning Parameters group allows you to define the constants 
associated with the PID control equation. The characteristic 
equation for a PID Controller is given below:
where:  
OP(t) = controller output at time t
OPss = steady state controller output (at zero error)
E(t) = error at time t
Kc = proportional gain of the controller
Ti = integral (reset) time of the controller
Td = derivative (rate) time of the controller
The error at any time is the difference between the Setpoint and 
the Process Variable:
Depending on which of the three tuning parameters you have 
specified, the Controller responds accordingly to the error. A 
Proportional-only controller is modeled by providing only a value 
for Kp, while a PI (Proportional-Integral) Controller requires 
values for Kp and Ti. Finally, the PID (Proportional-Integral-
Derivative) Controller requires values for all three of Kp, Ti, and 
Td.
(5.4)
(5.5)
OP t( ) OPss KcE t( )
Kc
Ti
----- E t( )dt KcTd+ E t( )d
dt
------------∫+ +=
E t( ) SP t( ) PV t( )–=5-64
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ThConfiguration Page
The Configuration page allows you to specify the process 
variable, setpoint, and output ranges.
PV: Min and Max Group
For the operation to become operational, you must:
1. Define the minimum and maximum values for the PV (the 
operation cannot switch from Off mode unless PVmin and 
PVmax are defined).
2. Once you provide these values (as well as the Control Valve 
span), you can select the Automatic mode and give a value 
for the Setpoint.  
 Figure 5.44
HYSYS uses the current value of the PV as the set point by 
default, but you can change this value at any time.
Without a PV span, the Controller cannot function.5-65
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ThHYSYS converts the PV range into a 0-100% range, which is 
then used in the solution algorithm. The following equation 
is used to translate a PV value into a percentage of the 
range:
SP Low and High Limits Group
In this group, you can specify the higher and lower limits for the 
setpoints to reflect your needs and safety requirements. The 
setpoint limits enforce an acceptable range of values that could 
be entered via the interface or from a remote source. By default 
the PVs min. and max values are used as the SPs low and high 
limits, respectively. 
Op Low and High Limits Group
In this group, you can specify the higher and lower limits for all 
the outputs. The output limits ensure that a predetermined 
minimum, or maximum output value is never exceeded. By 
default 0% and 100% is selected as a low and a high of limit, 
respectively for all the outputs.
(5.6)
When the Enable Op Limits in Manual Mode checkbox is 
selected, you can enable the set point and output limits 
when in manual mode.
PV %( )
PV PVmin–
PVmax PVmin–
-------------------------------------⎝ ⎠
⎛ ⎞ 100=5-66
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ThAdvanced Page
The Advanced page contains the following four groups described 
in the table below: 
The setpoint signal is specified in the Selected Sp Signal # 
field by clicking the up or down arrow button , or by typing 
the appropriate number in the field. 
Depending upon the signal selected, the page displays the 
respective setpoint settings.
 Figure 5.45
Group Description
Setpoint 
Ramping
Allows you to specify the ramp target and duration.
Setpoint Mode Contains the options for setpoint mode and tracking, 
as well as, the option for remote setpoint.
Setpoint Options Contains the option for setpoint tracking only in 
manual mode. 
Algorithm 
Selection
Contains the PID controller algorithms for output 
calculation.5-67
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ThSetpoint Ramping Group
The setpoint ramping function has been modified in the present 
MPC controllers. Now it is continuous, in other words, when set 
to on by clicking the Enable button, the setpoint changes over 
the specified period of time in a linear manner. 
The Setpoint Ramping group contains the following two fields:
• Target SP. Contains the Setpoint you want the 
Controller to have at the end of the ramping interval. 
When the ramping is turn off, the Target SP field display 
the same value as SP field on the Configuration page.
• Ramping. Contains the time interval you want to 
complete setpoint change in.
Besides these two fields there are also two buttons available in 
this group:
• Enable. Activates the ramping process.
• Disable. Stops the ramping process.
While the controller is in ramping mode, you can change the 
setpoint as follows:
• Enter a new setpoint in the Target SP field
• Enter a new setpoint in the SP field, on the Operation 
page.
 Figure 5.46
Setpoint ramping is only available in Auto mode.
Ramping Duration = RTSP
SP(t)
t t+RT Time
Target
SP
Controller Ramping5-68
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ThDuring the setpoint ramping the Target SP field shows the final 
value of the setpoint whereas the SP field, on the Operation 
page, shows the current setpoint seen internally by the control 
algorithm. 
Setpoint Mode Group
You have now the ability to switch the setpoint from local to 
remote using the Setpoint mode radio buttons. Essentially, there 
are two internal setpoints in the controller, the first is the local 
setpoint where the you can manually specify the setpoint via the 
property view (interface), and the other is the remote setpoint 
which comes from another object such as a spreadsheet or 
another controller cascading down a setpoint, in other words, a 
master in the classical cascade control scheme.
The Sp Local option allows you to disable the tracking for the 
local setpoint when the controller is placed in manual mode. You 
can also have the local setpoint track the remote setpoint by 
selecting the Track Remote radio button.
The Remote Sp option allows you to select either the Use% 
radio button (for restricting the setpoint changes to be in 
percentage) or Use Pv units radio button (for setpoint changes 
to be in Pv units).
• If the Remote Sp is set to Use%, then the controller 
reads in a value in percentage from a remote source, and 
using the Pv range calculates the new setpoint.
• If the Remote Sp is set to Use Pv units, then the 
controller reads in a value from a remote source, and 
sets a new setpoint. The remote source’s setpoint must 
have the same units as the controller Pv.
SetPoint Options Group
If you select the Track PV radio button then there is automatic 
setpoint tracking in manual mode, that sets the value of the 
During ramping, if a second setpoint change has been 
activated, then Ramping Duration time would be restarted 
for the new setpoint.5-69
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Thsetpoint equal to the value of the Pv prior to the controller being 
placed in the manual mode. This means that upon switching 
from manual to automatic mode the values of the setpoint and 
Pv were equal and, therefore, there was an automatic bumpless 
transfer.
Also you have the option not to track the Pv, by selecting the No 
Tracking radio button, when the controller is placed in manual 
mode. However, when the controller is switched into the 
automatic mode from manual, there is an internal resetting of 
the controller errors to ensure that there is an instantaneous 
bumpless transfer prior to the controller recognizing a setpoint 
that is different from the Pv. 
Algorithm Selection Group
In the Algorithm Selection group you can select one of the three 
available controller update algorithms:
• PID Velocity Form 
• PID Positional Form (ARW = Anti-Reset Windup)
• PID Positional Form (noARW)
Velocity or Differential Form
In the velocity or differential form, the controller equation is 
given as:
where:  
u(t) = controller output and t is the enumerated sampling 
instance in time
u(t-1) = value of the output one sampling period ago
The velocity or differential form of the controller should be 
applied when there is an integral term. When there is no 
integral term a positional form of the controller should be 
used.
(5.7)u t( ) u t 1–( ) Kc e t( ) e t( )– 1
Ti
----e kh( ) Td
e t( ) 2e t 1–( )– e t 2–( )+( )
h
------------------------------------------------------------------+ ++=5-70
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ThKc, Ti, and Td = controller parameters
h = sampling period
Positional Form
In the positional form of the algorithm, the controller output is 
given by:
Here it is important to handle properly the summation term 
associated with the integral part of the control algorithm. 
Specifically, the integral term could grow to a very large value in 
instances where the output device is saturated, and the PV is 
still not able to get to the setpoint. For situations like the one 
above, it is important to reset the value of the summation to 
ensure that the output is equal to the limit (upper or lower) of 
the controller output. As such, when the setpoint is changed to a 
region where the controller can effectively control, the controller 
responds immediately without having to decrease a summation 
term that has grown way beyond the upper or lower limit of the 
output. This is referred to as an automatic resetting of the 
control integral term commonly called anti-reset windup.
In HYSYS both algorithms are implemented as presented above 
with one key exception, there is no derivative kick. This means 
that the derivative part of the control algorithm operates on the 
process variable as opposed to the error term. 
As such the control equation given in Equation (5.7) is 
implemented as follows:
(5.8)
(5.9)
u t( ) Kc e t( ) e t( )– 1
Ti
---- e kh( )
k 0=
n
∑ Td
e t( ) e t 1–( )–( )
h
--------------------------------------+ +=
u t( ) u t 1–( ) Kc e t( ) e t( )– 1
Ti
----e kh( ) Td
pv– 2pv t 1–( ) pv t 2–( )–+( )
h
--------------------------------------------------------------------------+ ++=5-71
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ThAutotuning Page
You can set the autotuning parameters on the Autotuning page. 
This page consists two groups:
• Autotuner Parameters. Contains the parameters 
required by the Autotuner to calculate the controller 
parameters.
• Autotuner Results. Displays the resulting controller 
parameters. You have the option to accept the results as 
the current tuning parameters. 
Autotuner Parameters Group
In this group, you can specify the controller type by selecting 
the PID radio button or the PI radio button for the Design Type.
 Figure 5.47
In the present version of the software there are default 
values specified for the PID tuning. Before starting the 
autotuner, you must ensure that the controller is in the 
manual or automatic mode, and the process is relatively 
steady.
If you move the cursor over the tuning parameters field, the 
Status Bar displays the parameters range.
For more information 
about autotuning 
parameters, refer to the 
Autotuner Page in 
Section 5.4.4 - PID 
Controller.5-72
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ThIn the present autotuner implementation there are five 
parameters that you must specify which are as follows:
Autotuner Results Group
This group displays the results of the autotuner calculation, and 
allows you to accept the results as the current controller setting. 
The Start Autotuner button activates the tuning calculation, 
and the Stop Autotuning button aborts the calculations. 
After running the autotuner, you have the option to accepts the 
results either automatically or manually. Selecting the 
Automatically Accept checkbox sets the resulting controller 
parameters as the current value instantly. If the Automatically 
Accept checkbox is inactive, you can specify the calculated 
controller parameters to be the current setting by clicking the 
Accept button.
IMC Design Page
The IMC Design page allows you to use the internal model 
control (IMC) calculator to calculate the operation parameters 
based on a specified model of the process one is attempting to 
control.
Parameter Range
Ratio (Ti/Td) (Alpha)
Gain ratio (Beta)
Phase angle (Phi) 
Relay hysteresis (h)
Relay amplitude (d)
3.0 α 6.0≤ ≤
0.10 β 1.0≤ ≤
30° φ 65°≤ ≤
0.01% h 5.0%≤ ≤
0.5% d 10.0%≤ ≤5-73
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Th 
The IMC method is quite common in most of the process 
industries and has a very solid theoretical basis. In general, the 
performance obtained using this design methodology is superior 
to most of the existing techniques for tuning PIDs. As such, 
when there is a process model available (first order plus delay) 
this approach should be used to determine the controller 
parameters. You must specify a design time constant, which is 
usually chosen as three times that of the measured process time 
constant.
The IMC Design page has the following two groups: 
As soon as you enter the parameters in the Process Model 
group, the operation parameters are calculated and displayed in 
the IMC PID Tuning group. You can accept them as the current 
tuning parameters by clicking the Update Tuning button.
 Figure 5.48
Group Description
Process Model Contains the parameters for the process model, which 
are required by the IMC calculator.
• Process Gain
• Process Time Constraint
• Process Delay
• Design To
IMC PID Tuning Displays the operation parameters.5-74
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ThScheduling Page
The Scheduling page gives you the ability to do parameter 
scheduling. This feature is quite useful for nonlinear processes 
where the process model changes significantly over the region 
of operation. 
The parameter scheduling is activated through the Parameter 
Schedule checkbox. You can use three different sets of PID 
parameters, if you so desires for three different regions of 
operation. 
The following regions of operation can be specified from the 
Selected Range drop-down list.
• Low Range
• Middle Range
• High Range
These regions of operations can be based either on the setpoint, 
or PV of the controller. The ranges can also be specified, the 
default values are 0-33%, 33%-66%, and 66%-100% of the 
selected scheduling signal. You need to specify the middle range 
limit by defining the Upper and Lower Range Limits.
 Figure 5.495-75
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ThAlarms Page
The Alarms page allows you to set alarm limits on all exogenous 
inputs to and outputs from the controller. 
The Alarms page contains two groups:
• Alarm Levels
• Alarms
Alarm Levels Group
The Alarm Level group allows you to set, and configure the 
alarm points for a selected signal type. There are four alarm 
points that could be configured:
• LowLow
• Low
• High
• HighHigh
The values of 0 and 100 cannot be specified for both the 
Lower and the Upper Range Limits.
 Figure 5.505-76
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ThThe alarm points should be specified in the descending order 
from HighHigh to LowLow points. You cannot specify the value of 
the Low and LowLow alarm points to be higher than the signal 
value. Similarly, the High and HighHigh alarm points cannot be 
specified to a value lower than the signal value. Also, no two 
alarm points can be specified to a similar value. In addition, you 
can specify a deadband for a given set of alarms. This can be 
helpful in situations where the signal is “noisy” to avoid constant 
triggering of the alarm. If a deadband is specified, you have to 
specify the alarm points so that their difference is greater than 
the deadband. At present the range for the allowable deadband 
is as follows:
 of the signal range.
Alarms Group
The Alarms group displays the recently violated alarm for the 
following signals:
The above limits are set internally, and are not available for 
adjustment by the user.
Signal Description
PV Process Variable
OP Output
SP Setpoint
0.0% deadband 1.5%≤ ≤5-77
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ThSignal Processing Page
The Signal Processing page allows you to add filters to any 
signal associated with the operation, as well as test the 
robustness of any tuning on the controller.
This page consists of two groups:
• Signal Filters
• Noise Parameters
Both of these groups allow you to filter, and test the robustness 
of the following tuning parameters:
• Pv
• Op
• Sp
• Dv
• Rs
To apply the filter select the checkbox corresponding to the 
signal you want to filter. Once active, you can specify the filter 
time. As you increase the filter time you are filtering out 
frequency information from the signal. 
For example, the signal is noisy, there is a smoothing effect 
noticed on the plot of the PV. Notice that it is possible to add a 
filter that makes the controller unstable. In such cases the 
 Figure 5.515-78
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Thcontroller needs to be returned. Adding a filter has the same 
effect as changing the process, which the controller is trying to 
control.
Activating a Noise Parameter is done the same way as adding a 
filter. However, instead of specifying a filter time you are 
specifying a variance. Notice that if a high variance on the PV 
signal is chosen the controller may become unstable. As you 
increase the noise level for a given signal you observe a some 
what random variation of the signal.
Initialization Page
The Initialization page allows you to initialize an appropriate OP 
value to start the controller smoothly. To back initialize the 
controller, click on the Back Initialization button and HYSYS will 
initialize the controller output based on the current position of 
the executor (for example, a valve or another controller). The 
current back initialization OP value is displayed in the OP value 
field.
Since the split controller has two outputs (two OP values), you 
can click on the Output1 or Output2 radio button to chose which 
OP value you want to use to back initialize the controller.
 Figure 5.525-79
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ThSplit Range Setup Tab
The Split Range Setup tab allows you to specify the split ranges 
for the controller. The Split Range Setup tab consists of three 
groups: Split Range Setup, PID Values, and Split Range Outputs.
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
 Figure 5.53
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-80
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Th5.4.3 Ratio Controller
In the Ratio Controller the objective is to keep the ratio of two 
variables, the load and the manipulated, constant. 
The Ratio Controller is a special type of feedforward control, and 
can be implemented in two ways: 
• Method 1. The actual ratio of the two variables is 
calculated using a divider, and is sent on to the ratio 
controller in which the setpoint is the required ratio.
• Method 2. The value of the load variable is measured 
and sent to a ratio station, which then calculates the 
setpoint of the manipulated (second) variable.
The inclusion of a divider in approach (method 1) renders the 
methodology less desirable since it results in a loop in which the 
process gain varies in a nonlinear manner as a result of the 
included divider. As such, method (2) is the preferred way of 
doing the ratio implementation, and is the approached followed 
in this implementation for HYSYS.
 Figure 5.545-81
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ThThe Ratio Controller property view contains the following tabs:
• Connections
• Parameters
• Stripchart
• User Variables
Connections Tab
On the Connections tab, you can select the process variable 
source, and the output target object. You can also select a 
remote setpoint value. 
 Figure 5.55
Object Description
Name Allows you to change the name of the operation.
Process Variable 
Source: Object
Contains the Process Variable Object (stream or 
operation) that owns the variable you want to 
compare.
Process Variable 
Source: Variable
Contains the Process Variable you want to compare.
Output Target 
Object
The stream or valve, which is controlled by the 
operation.
Select PV/OP These two buttons open the Variable Navigator which 
selects the Process Variable and the Output Target 
Object respectively.
Remote Setpoint 
Source
If you are using set point from a remote source, select 
the remote Setpoint Source associated with the Master 
controller
Click the up 
and down 
arrows to 
access the 
first and 
second 
variables.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-82
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ThParameters Tab
The Parameters tab contains the following pages:
• Operation
• Configuration
• Advanced
• Autotuning
• IMC Design
• Scheduling
• Alarms
• Signal Processing
• Initialization
Operation Page
On the Operation page, you can manipulate how the operation 
reacts to the process variable inputs. 
 Figure 5.565-83
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ThObject Description
Action You can select one of the two types of action available for 
the operation to take when the process variable value 
deviates from the setpoint value:
• Direct. When the PV rises above the SP, the OP 
increases. When the PV falls below the SP, the OP 
decreases.
• Reverse. When the PV rises above the SP, the OP 
decreases. When the PV falls below the SP, the OP 
increases.
Controller 
Mode
You can select from three types of controller mode:
• Off. The operation does not manipulate the control 
valve, although the appropriate information is still 
tracked.
• Manual. Manipulate the operation output manually.
• Automatic. The operation reacts to fluctuations in the 
Process Variable and manipulates the Output 
according to the logic defined by the tuning 
parameters.
Execution You can select from two types of execution.
• Internal. Confines the signals generated to stay 
within HYSYS.
• External. Sends the signals to a DCS, if a DCS is 
connected to HYSYS.
Enable Ratio 
Control
This checkbox has to be selected, if you want to set the 
ratio value for the operation.
If this checkbox is inactive, HYSYS calculates the ratio 
value between the two selected process variables.
Ref. Pv The value in this field is used to calculate the setpoint along 
with the ratio.
Ratio Displays the set or calculated ratio value between the 
selected the two process variables.
Sp Allows you to specify the setpoint value.
Pv Displays the process variable value.
Op Displays the output value.
Gain Allows you to specify the proportional gain of the operation. 
Reset Allows you to specify the integral (reset) time of the 
operation. 
Derivative Allows you to specify the derivative (rate) time of the 
operation. 
Refer to the Tuning 
Parameters Group 
section for more 
information on Gain, 
Reset, and Derivative.5-84
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ThTuning Parameters Group
The Tuning Parameters group allows you to define the constants 
associated with the PID control equation. The characteristic 
equation for a PID Controller is given below:
where:  
OP(t) = controller output at time t
OPss = steady state controller output (at zero error)
E(t) = error at time t
Kc = proportional gain of the controller
Ti = integral (reset) time of the controller
Td = derivative (rate) time of the controller
The error at any time is the difference between the Setpoint and 
the Process Variable:
Depending on which of the three tuning parameters you have 
specified, the Controller responds accordingly to the error. A 
Proportional-only controller is modeled by providing only a value 
for Kp, while a PI (Proportional-Integral) Controller requires 
values for Kp and Ti. Finally, the PID (Proportional-Integral-
Derivative) Controller requires values for all three of Kp, Ti, and 
Td.
(5.10)
(5.11)
OP t( ) OPss KcE t( )
Kc
Ti
----- E t( )dt KcTd+ E t( )d
dt
------------∫+ +=
E t( ) SP t( ) PV t( )–=5-85
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ThConfiguration Page
The Configuration page allows you to specify the process 
variable, setpoint, and output ranges.
PV: Min and Max Group
For the operation to become operational, you must:
1. Define the minimum and maximum values for the PV (the 
operation cannot switch from Off mode unless PVmin and 
PVmax are defined).
2. Once you provide these values (as well as the Control Valve 
span), you can select the Automatic mode and give a value 
for the Setpoint. 
HYSYS converts the PV range into a 0-100% range, which is 
then used in the solution algorithm. 
 Figure 5.57
HYSYS uses the current value of the PV as the set point by 
default, but you can change this value at any time.
Without a PV span, the Controller cannot function.5-86
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ThThe following equation is used to translate a PV value into a 
percentage of the range:
SP Low and High Limits Group
In this group, you can specify the higher and lower limits for the 
Setpoints to reflect your needs and safety requirements. The 
Setpoint limits enforce an acceptable range of values that could 
be entered via the interface or from a remote source. By default 
the PVs min. and max values are used as the SPs low and high 
limits, respectively. 
Op Low and High Limits Group
In this group, you can specify the higher and lower limits for all 
the outputs. The output limits ensure that a predetermined 
minimum or maximum output value is never exceeded. By 
default 0% and 100% is selected as a low and a high of limit, 
respectively for all the outputs.
When the Enable Op Limits in Manual Mode checkbox is 
selected, you can enable the set point and output limits when in 
manual mode.
(5.12)PV %( )
PV PVmin–
PVmax PVmin–
-------------------------------------⎝ ⎠
⎛ ⎞ 100=5-87
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ThAdvance Page
The Advanced page contains the following four groups: 
The setpoint signal is specified in the Selected Sp Signal # 
field by clicking the up or down arrow button , or typing the 
appropriate number in the field. 
Depending upon the signal selected, the Advance page displays 
the respective setpoint settings.
Setpoint Ramping Group
The setpoint ramping function has been modified in the present 
MPC controllers. Now it is continuous, in other words, when set 
to on by clicking the Enable button, the setpoint changes over 
 Figure 5.58
Group Description
Setpoint 
Ramping
Allows you to specify the ramp target and duration.
Setpoint Mode Contains the options for setpoint mode and tracking as 
well as the option for remote setpoint.
Setpoint Options Contains the option for setpoint tracking only in 
manual mode. 
Algorithm 
Selection
Contains the PID controller algorithms for output 
calculation.5-88
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Ththe specified period of time in a linear manner. The Setpoint 
Ramping group contains the following two fields:    
Besides these two fields there are also two buttons available in 
this group:
• Enable. Activates the ramping process.
• Disable. Stops the ramping process.
While the controller is in ramping mode, you can change the 
setpoint as follows:
• Enter a new setpoint in the Target SP field.
• Enter a new setpoint in the SP field, on the Operation 
page.
During the setpoint ramping the Target SP field shows the final 
value of the setpoint whereas the SP field, on the Operation 
page, shows the current setpoint seen internally by the control 
algorithm.
Field Input Required
Target SP Contains the Setpoint you want the Controller to have 
at the end of the ramping interval. When the ramping 
is turn off, the Target SP field display the same value 
as SP field on the Configuration page.
Ramping 
Duration
Contains the time interval you want to complete 
setpoint change in. 
Setpoint ramping is only available in Auto mode.
 Figure 5.59
Ramping Duration = RTSP
SP(t)
t t+RT Time
Target
SP
Controller Ramping5-89
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ThSetpoint Mode Group
You have now the ability to switch the setpoint from local to 
remote using the Setpoint mode radio buttons. Essentially, there 
are two internal setpoints in the controller, the first is the local 
setpoint where you can manually specify the setpoint via the 
property view (interface), and the other is the remote setpoint 
which comes from another object such as a spreadsheet or 
another controller cascading down a setpoint, in other words, a 
master in the classical cascade control scheme.
The Sp Local option allows you to disable the tracking for the 
local setpoint when the controller is placed in manual mode. You 
can also have the local setpoint track the remote setpoint by 
selecting the Track Remote radio button.
The Remote Sp option allows you to select either the Use% 
radio button (for restricting the setpoint changes to be in 
percentage) or Use Pv units radio button (for setpoint changes 
to be in Pv units).
• If the Remote Sp is set to Use%, then the controller 
reads in a value in percentage from a remote source, and 
using the Pv range calculates the new setpoint.
• If the Remote Sp is set to Use Pv units, then the 
controller reads in a value from a remote source and sets 
a new setpoint. The remote source’s setpoint must have 
the same units as the controller Pv.
SetPoint Options Group
If you select the Track PV radio button, then there is automatic 
setpoint tracking in manual mode, that sets the value of the 
setpoint equal to the value of the Pv prior to the controller being 
placed in the manual mode. This means that upon switching 
from manual to automatic mode the values of the setpoint and 
During ramping, if a second setpoint change has been 
activated, then Ramping Duration time would be restarted 
for the new setpoint.5-90
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ThPv were equal and, therefore, there was an automatic bumpless 
transfer.
Also you have the option not to track the pv, by clicking the No 
Tracking radio button, when the controller is placed in manual 
mode. However, when the controller is switched into the 
automatic mode from manual, there is an internal resetting of 
the controller errors to ensure that there is an instantaneous 
bumpless transfer prior to the controller recognizing a setpoint 
that is different from the Pv. 
Algorithm Selection Group
In the Algorithm Selection group you can select one of three 
available controller update algorithms:
• PID Velocity Form 
• PID Positional Form (ARW = Anti-Reset Windup)
• PID Positional Form (noARW)
Velocity or Differential Form
In the velocity or differential form the controller equation is 
given as:
where:  
u(t) = controller output and t is the enumerated sampling 
instance in time
u(t-1) = value of the output one sampling period ago
Kc, Ti, and Td = controller parameters
h = sampling period
The velocity or differential form of the controller should be 
applied when there is an integral term. When there is no 
integral term a positional form of the controller should be 
used.
(5.13)u t( ) u t 1–( ) Kc e t( ) e t( )– 1
Ti
----e kh( ) Td
e t( ) 2e t 1–( )– e t 2–( )+( )
h
------------------------------------------------------------------+ ++=5-91
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ThPositional Form
In the positional form of the algorithm, the controller output is 
given by:
Here it is important to handle properly the summation term 
associated with the integral part of the control algorithm. 
Specifically, the integral term could grow to a very large value in 
instances where the output device is saturated and the PV is still 
not able to get to the setpoint. 
For situations like the one above, it is important to reset the 
value of the summation to ensure that the output is equal to the 
limit (upper or lower) of the controller output. As such, when the 
setpoint is changed to a region where the controller can 
effectively control, the controller responds immediately without 
having to decrease a summation term that has grown way 
beyond the upper or lower limit of the output. This is referred to 
as an automatic resetting of the control integral term commonly 
called anti-reset windup.
In HYSYS both algorithms are implemented as presented above 
with one key exception, there is no derivative kick. This means 
that the derivative part of the control algorithm operates on the 
process variable as opposed to the error term. 
As such the control equation given in Equation (5.13) is 
implemented as follows:
(5.14)
(5.15)
u t( ) Kc e t( ) e t( )– 1
Ti
---- e kh( )
k 0=
n
∑ Td
e t( ) e t 1–( )–( )
h
--------------------------------------+ +=
u t( ) u t 1–( ) Kc e t( ) e t( )– 1
Ti
----e kh( ) Td
pv– 2pv t 1–( ) pv t 2–( )–+( )
h
--------------------------------------------------------------------------+ ++=5-92
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ThAutotuning Page
You can set the autotuning parameters on the Autotuning page. 
This page consists of two groups:
• Autotuner Parameters. Contains the parameters 
required by the Autotuner to calculate the controller 
parameters.
• Autotuner Results. Displays the resulting controller 
parameters. You have the option to accept the results as 
the current tuning parameters.   
Autotuner Parameters Group
In this group, you can specify the controller type by selecting 
the PID radio button or the PI radio button for the Design Type. 
In the present autotuner implementation there are five 
parameters that you must specify, which are as follows: 
 Figure 5.60
Parameter Range
Ratio (Ti/Td) (Alpha)
Gain ratio (Beta)
Phase angle (Phi) 
For more information 
about autotuning 
parameters, refer to the 
Autotuner Page in 
Section 5.4.4 - PID 
Controller.
3.0 α 6.0≤ ≤
0.10 β 1.0≤ ≤
30° φ 65°≤ ≤5-93
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ThIn the present version of the software there are default values 
specified for the PID tuning. Before starting the autotuner, you 
must ensure that the controller is in the manual or automatic 
mode, and the process is relatively steady.
If you move the cursor over the tuning parameters field, the 
Status Bar displays the parameters range.
Autotuner Results Group
This group displays the results of the autotuner calculation and 
allows you to accept the results as the current controller setting. 
The Start Autotuner button activates the tuning calculation, 
and the Stop Autotuning button abort the calculations. 
After running the autotuner, you have the option to accept the 
results either automatically or manually. Selecting the 
Automatically Accept checkbox sets the resulting controller 
parameters as the current value instantly. If the Automatically 
Accept checkbox is inactive, you can specify the calculated 
controller parameters to be the current setting by clicking the 
Accept button.
Relay hysteresis (h)
Relay amplitude (d)
Parameter Range
0.01% h 5.0%≤ ≤
0.5% d 10.0%≤ ≤5-94
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ThIMC Design Page
The IMC Design page allows you to use the internal model 
control (IMC) calculator to calculate the operation parameters 
based on a specified model of the process one is attempting to 
control.
The IMC method is quite common in most of the process 
industries, and has a very solid theoretical basis. In general, the 
performance obtained using this design methodology is superior 
to most of the existing techniques for tuning PIDs. As such, 
when there is a process model available (first order plus delay) 
this approach should be used to determine the controller 
parameters. You must specify a design time constant, which is 
usually chosen as three times that of the measured process time 
constant.
 Figure 5.615-95
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ThThe IMC Design page has the following two groups described in 
the table below: 
As soon as you enter the parameters in the Process Model 
group, the operation parameters are calculated and displayed in 
the IMC PID Tuning group. You can accept them as the current 
tuning parameters by clicking the Update Tuning button.
Scheduling Page
The Scheduling page gives you the ability to do parameter 
scheduling. This feature is quite useful for nonlinear processes 
where the process model changes significantly over the region 
of operation. 
The parameter scheduling is activated through the Parameter 
Schedule checkbox. You can use three different sets of PID 
Group Description
Process Model Contains the parameters for the process model which 
are required by the IMC calculator.
• Process Gain
• Process Time Constraint
• Process Delay
• Design To
IMC PID Tuning Displays the operation parameters.
 Figure 5.625-96
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Thparameters if you so desire for three different regions of 
operation. The following regions of operation can be specified 
from the Selected Range drop-down list.
• Low Range
• Middle Range
• High Range
These regions of operations can be based either on the setpoint, 
or PV of the controller. The ranges can also be specified, the 
default values are 0-33%, 33%-66%, and 66%-100% of the 
selected scheduling signal. You need to specify the middle range 
limit by defining the Upper and Lower Range Limits.
Alarms Page
The Alarms page allows you to set alarm limits on all exogenous 
inputs to and outputs from the controller. 
The Alarms page contains two groups:
• Alarm Levels
• Alarms
The values of 0 and 100 cannot be specified for both the 
Lower and the Upper Range Limits.
 Figure 5.635-97
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ThAlarm Levels Group
The Alarm Level group allows you to set, and configure the 
alarm points for a selected signal type. There are four alarm 
points that could be configured:
• LowLow
• Low
• High
• HighHigh
The alarm points should be specified in the descending order 
from HighHigh to LowLow points. You cannot specify the value of 
the Low and LowLow alarm points to be higher than the signal 
value. Similarly, the High and HighHigh alarm points cannot be 
specified to a value lower than the signal value. Also, no two 
alarm points can be specified to a similar value. In addition, you 
can specify a deadband for a given set of alarms. This can be 
helpful in situations where the signal is “noisy” to avoid constant 
triggering of the alarm. If a deadband is specified, you have to 
specify the alarm points so that their difference is greater than 
the deadband. At present the range for the allowable deadband 
is as follows:
 of the signal range.
Alarms Group
The Alarms group displays the recently violated alarm for the 
following signals:
The above limits are set internally and are not available for 
adjustment by the user.
Signal Description
PV Process Variable
OP Output
SP Setpoint
0.0% deadband 1.5%≤ ≤5-98
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ThSignal Processing Page
The Signal Processing page allows you to add filters to any 
signal associated with the operation, as well as test the 
robustness of any tuning on the controller.
This page consists of two groups:
• Signal Filters
• Noise Parameters 
Both of these groups allow you to filter, and test the robustness 
of the following tuning parameters:
• Pv
• Op
• Sp
• Dv
• Rs
To apply the filter select the checkbox corresponding to the 
signal you want to filter. Once active you can specify the filter 
time. As you increase the filter time you are filtering out 
frequency information from the signal. For example, the signal 
is noisy, there is a smoothing effect noticed on the plot of the 
PV. Notice that it is possible to add a filter that makes the 
controller unstable. In such cases the controller needs to be 
 Figure 5.645-99
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Threturned. Adding a filter has the same effect as changing the 
process the controller is trying to control.
Activating a Noise Parameter is done the same way as adding a 
filter. However, instead of specifying a filter time you are 
specifying a variance. Notice that if a high variance on the PV 
signal is chosen the controller may become unstable. As you 
increase the noise level for a given signal you observes a some 
what random variation of the signal.
Initialization Page
The Initialization page allows you to set up a sophisticated 
controller by taking into account the problem of saturation in 
cascade control, and the need for an appropriate initial output 
value to ensure a smooth start-up. The Initialization page 
consists of two features:
• Back Initialization
• Cascade Control Anti Windup
 Figure 5.655-100
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ThBack Initialization
A proper initial OP Value is supplied to the controller to ensure 
the integration runs smoothly during start up. The Back 
Initialization button is used to initialize the controller output 
based on the current position of the executor (for example, a 
valve, a stream, or another controller). This prevents 
disturbances in the system during the initial switch-over.
Cascade Control Anti Windup
A common problem associated with cascade control is 
saturation. Saturation occurs when the primary controller 
continues to integrate and send out correction signals to the 
secondary controller even when the output of the secondary 
controller is already at its designed limit. As a result, when the 
primary offset changes (decreases or increases), the primary 
controller cannot respond accordingly until it overcomes the 
saturation. By the time this happens, the primary offset is once 
again too large to be adjusted. This severely reduces the 
controller performance and even creates an unstable system as 
the output is always fluctuating.
The Cascade Control Anti Windup checkbox allows you to 
prevent saturation by having the primary controller 
automatically calculate the feasible output that can be executed 
by the secondary controller. Once the primary controller detects 
that the output of the secondary controller has reached its limit 
(upper or lower), the primary controller will not integrate any 
further from getting into saturation. Thus, when the offset 
changes, both the primary and secondary controllers can react 
immediately without having to wait for the saturation to clear.
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
For more information on 
the cascade control 
strategy, refer to Section 
3.3 - Basic Control in 
the HYSYS Dynamic 
Modeling guide.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.5-101
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ThUser Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
5.4.4 PID Controller
The Controller operation is the primary means of manipulating 
the model in Dynamic mode. It adjusts a stream (OP) flow to 
maintain a specific flowsheet variable (PV) at a certain value 
(SP). 
The PID Controller property view contains the following tabs:
• Connections
• Parameters
• Monitor
• Stripchart
• User Variables 
The Controller can cross the boundaries between flowsheets, 
enabling you to sense a process variable in one flowsheet 
and control a valve in another.
 Figure 5.66
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-102
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ThConnections Tab
The Connections tab allows you to select both the PV and OP. It 
is comprised of six objects described in the table below: 
Process Variable Source
Common examples of PVs include vessel pressure and liquid 
level, as well as stream conditions such as flow rate or 
temperature.
Object Description
Name Contains the name of the controller. It can be edited 
by selecting the field and entering the new name.
Process Variable 
Source Object
Contains the Process Variable Object (stream or 
operation) that owns the variable you want to control. 
It is specified via the Variable Navigator.
Process Variable Contains the Process Variable you want to control.
Output Target 
Object
The stream or valve, which is controlled by the PID 
Controller operation 
Select PV/OP These two buttons open the Variable Navigator which 
selects the Process Variable and the Output Target 
Object respectively.
Remote Setpoint 
Source
If you are using set point from a remote source, select 
the remote Setpoint Source associated with the Master 
controller
 Figure 5.675-103
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ThTo attach the Process Variable Source, click the Select PV 
button. Then select the appropriate object and variable 
simultaneously, using the Variable Navigator. 
The Variable Navigator property view allows you to 
simultaneously select the Object and Variable.
Remote Setpoint Source
The Remote Setpoint Source drop-down list allows you to select 
the remote sources from a list of existing operations.
The “cascade” mode of the controller no longer exits. Instead 
what is available now is the ability to switch the setpoint from 
local to remote. The remote setpoint can come from another 
object such as a spreadsheet, or another controller cascading 
down a setpoint. In other words, a master in the classical 
cascade control scheme.
The Process Variable, or PV, is the variable that must be 
maintained, or controlled at a desired value.
 Figure 5.68
1. Select flowsheet or 
subflowsheet.
2. Then select the 
Object within the 
respective flowsheet.
3. Then select the 
object Variable (and 
the Variable Specific 
when appropriate).
A Spreadsheet cell can also be a Remote Setpoint Source.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-104
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ThWhen the spreadsheet exports any PID parameter (gain, Ti, 
and/or Td) to a PID controller, the controller calls 
ControllerInitialization(), which is required for smooth switch 
when the user change the PID parameters. However, if there is 
an export variable connected an output object, the spreadsheet 
updates the output every integration step even if the value has 
not changed. So with the spreadsheet constantly changing the 
PID parameter values in every integration step, the PID will not 
be functioning.
Output Target Object
The Controller compares the Process Variable to the Setpoint, 
and produces an output signal which causes the manipulated 
variable to open or close appropriately.
Selecting the Output Target Object is done in a similar manner 
to selecting the Process Variable Source. You are also limited to 
objects supported by the controller and not currently attached 
to another controller.
The information regarding the control valve or control op port 
sizing is contained on a sub-view accessed by clicking the 
Control Valve or Control OP Port button found at the bottom 
of the PID Controller property view.
When PID parameters are exported to a PID controller from 
a HYSYS spreadsheet, the controller gets initialized at each 
time step.
The Output of the Controller is the control valve which the 
Controller manipulates in order to reach the set point. The 
output signal, or OP, is the desired percent opening of the 
control valve, based on the operating range which you define 
in the Control Valve property view.
The Control Valve button (at the bottom right corner of the 
controller operation property view) appears if the OP is a 
stream.5-105
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ThParameters Tab
The Parameters tab contains the following pages:
• Configuration
• Advanced
• Autotuner
• IMC Design
• Scheduling
• Alarms
• PV Conditioning
• Signal Processing
• FeedForward
• Model Testing
• Initialization
Configuration Page
The Configuration page allows you to set the process variable 
range, controller action, operating mode, and depending on the 
The Control OP Port button (at the bottom right corner of the 
controller operation property view) appears when the OP is 
not a stream and there a range of specified values is 
required.5-106
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Logical Operations 5-107
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Thmode, either the SP or OP, as well as tune the controller.
PV and SP
The PV (or Process Variable) is the measured variable, which the 
controller is trying to keep at the Setpoint.
The SP (or Setpoint) is the value of the Process Variable, which 
the Controller is trying to meet. Depending on the Mode of the 
Controller, the SP is either entered by the user or displayed only.
For the Controller to become operational, you must:
1. Define the minimum and maximum values for the PV (the 
Controller cannot switch from Off mode unless PVmin and 
PVmax are defined).
2. Once you provide these values (as well as the Control Valve 
span), you may select the Automatic mode, and give a value 
for the Setpoint. 
HYSYS converts the PV range into a 0-100% range, which is 
then used in the solution algorithm. The following equation 
is used to translate a PV value into a percentage of the 
 Figure 5.69
HYSYS uses the current value of the PV as the set point by 
default, but you may change this value at any time.
Without a PV span, the Controller cannot function.5-107
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Thrange:
OP
The OP (or Output) is the percent opening of the control valve. 
The Controller manipulates the valve opening for the output 
stream in order to reach the set point. HYSYS calculates the 
necessary OP using the controller logic in all modes with the 
exception of Manual. In Manual mode, you may input a value for 
the output, and the setpoint becomes whatever the PV is at the 
particular valve opening you specify.
Modes
The Controller operates in any of the following modes:
The mode of the controller can also be set on the Face Plate.
Execution
You can select where the signal from the controller is sent using 
the drop-down list in the Execution field. You have two 
selections:
(5.16)
Controller Mode Description
Off The controller does not manipulate the control valve, 
although the appropriate information is still tracked.
Manual Manipulates the controller output manually.
Auto The controller reacts to fluctuations in the Process 
Variable, and manipulates the output according to the 
logic defined by the tuning parameters.
Casc The main controller reacts to the fluctuations in the 
Process Variable, and sends signals to the slave 
controller (Remote Setpoint Source).
Indicator Allows you to simulate the controller without 
controlling the process.
PV %( )
PV PVmin–
PVmax PVmin–
-------------------------------------⎝ ⎠
⎛ ⎞ 100=
Refer to Section 5.13.2 
- Controller Face Plate 
for more information on 
Face Plate.5-108
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Th• Internal. Confines the signals generated to stay within 
HYSYS.
• External. Sends the signals to a DCS, if a DCS is 
connected to HYSYS.
Action
There are two options for the Action of the controller, which are 
described in the table below:
The Controller equation given above applies to a Reverse-acting 
Controller. That is, when the PV rises above the SP, the error 
becomes negative and the OP decreases. For a Direct-response 
Controller, the OP increases when the PV rises above the SP. 
This action is made possible by replacing Kp with -Kp in the 
Controller equation. A typical example of a Reverse Acting 
controller is in the temperature control of a Reboiler. In this 
case, as the temperature in the vessel rises past the SP, the OP 
decreases, in effect closing the valve and hence the flow of heat. 
Some typical examples of Direct-Acting and Reverse-Acting 
control situations are given below.
• Direct - Acting Controller Example 1: Flow Control in a 
Tee
Suppose you have a three-way tee in which a feed 
stream is being split into two exit streams. You want to 
control the flow of exit stream Product 1 by manipulating 
the flow of stream Product 2:
• Direct - Acting Controller Example 2: Pressure Control in 
a Vessel
Controller Action Description
Direct When the PV rises above the SP, the OP increases. 
When the PV falls below the SP, the OP decreases.
Reverse When the PV rises above the SP, the OP decreases. 
When the PV falls below the SP, the OP increases.
Process Variable and 
Setpoint
Product 1 Flow
Output Product 2 Flow
When Product 1 Flow 
rises above the SP 
The OP increases, in effect increasing the flow of 
Product 2 and decreasing the flow of Product 1.
When Product 1 Flow 
falls below the SP 
The OP decreases, in effect decreasing the flow of 
Product 2 and increasing the flow of Product 1.5-109
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ThSuppose you were controlling the pressure of a vessel V-
100 by adjusting the flow of the outlet vapour, 
SepVapour:
• Reverse - Acting Controller Example 1: Temperature 
Control in a Reboiler
Reverse-Acting control may be used when controlling the 
temperature of reboiler R-100 by adjusting the flow of 
the duty stream, RebDuty:
• Reverse - Acting Controller Example 2: Pressure Control 
in a Reboiler
Another example where Reverse-Acting control may be 
used is when controlling the stage pressure of a reboiler 
R-100 by adjusting the flow of the duty stream, 
RebDuty:
Process Variable and 
Setpoint
V-100 Vessel Pressure
Output SepVapour Flow
When V-100 Pressure 
rises above the SP
The OP increases, in effect increasing the flow 
of SepVapour and decreasing the Pressure of 
V-100.
When V-100 Pressure 
falls below the SP
The OP decreases, in effect decreasing the 
flow of SepVapour and increasing the 
Pressure of V-100.
Process Variable and 
Setpoint
R-100 Temperature
Output RebDuty Flow
When R-100 
Temperature rises above 
the SP
The OP decreases, in effect decreasing the 
flow of RebDuty and decreasing the 
Temperature of R-100.
When R-100 
Temperature falls below 
the SP
The OP increases, in effect increasing the flow 
of RebDuty and increasing the Temperature of 
R-100.
Process Variable and 
Setpoint
R-100 Stage Pressure
Output RebDuty Flow
When R-100 Stage 
Pressure rises above the 
SP
The OP decreases, in effect decreasing the 
flow of RebDuty and decreasing the Stage 
Pressure of R-100.
When R-100 Stage 
Pressure falls below the 
SP
The OP increases, in effect increasing the flow 
of RebDuty and increasing the Stage Pressure 
of R-100.5-110
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ThSP Mode
You have the ability to switch the setpoint from local to remote. 
Essentially, there are two internal setpoints in the controller, the 
first is the local setpoint where you can manually specify the 
setpoint via the property view (interface), and the other is the 
remote setpoint which comes from another object such as a 
spreadsheet or another controller cascading down a setpoint. In 
other words, a master in the classical cascade control scheme.
Tuning Parameters and Algorithm 
Selection Groups
From the Algorithm Type selector, you can choose PID 
algorithms of four possible types or vendors:
• Hysys
• Honeywell
• Foxboro
• Yokogawa
each of them offering a set of options or Algorithm Subtypes. 
See the HYSYS Online help for specific details on these options.
Advanced Page
The Advanced page contains the following four groups: 
Group Description
Set Point 
Ramping
Allows you to specify the ramp target and duration.
SetPoint Options Contains the options for setpoint tracking. 
Sp and Op Limits Allows you to set the upper and lower limits for set 
point and output targets.
Algorithm 
Selection
Contains the PID controller algorithms for output 
calculation.5-111
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ThSet Point Ramping Group
The setpoint ramping function has been modified in the present 
PID controllers. Now it is continuous (in other words, when 
enabled by clicking the Enable button), the setpoint changes 
over the specified period of time in a linear manner.
The Set Point Ramping group contains the following two fields: 
• Target SP. Contains the Setpoint you want the 
Controller to have at the end of the ramping interval. 
When the ramping is disabled, the Target SP field 
displays the same value as the SP field on the 
Configuration page.
 Figure 5.70
Setpoint ramping is only available in Auto mode.5-112
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Th• Ramp Duration. Contains the time interval you want to 
complete setpoint change in. 
There are also two buttons available in this group:
• Enable. Activates the ramping process
• Disable. Stops the ramping process.
While the controller is in ramping mode, you can change the 
setpoint as follows:
• Enter a new setpoint in the Target SP field, on this page.
• Enter a new setpoint in the SP field, on the Configuration 
page.
During the setpoint ramping the Target SP field, shows the final 
value of the setpoint whereas the SP field, on the Configuration 
page, shows the current setpoint seen internally by the control 
algorithm.
An example, if you click the Enable button and enter values for 
the two parameters in the Set Point Ramping group, the 
Controller switches to Ramping mode and adjust the Setpoint 
linearly (to the Target SP) during the Ramp Duration, see 
Figure 5.72. 
 Figure 5.71
During ramping, if a second setpoint change has been 
activated, then Ramping Duration time would be restarted 
for the new setpoint.
Ramping Duration = RTSP
SP(t)
t t+RT Time
Target SP
Controller Ramping5-113
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ThFor example, suppose your current SP is 100, and you want to 
change it to 150. Rather than creating a sudden, large 
disruption by manually changing the SP while in Automatic 
mode, click the Enable button and enter an SP of 150 in the 
Target SP input cell. Make the SP change occur over, say, 10 
minutes by entering this time in the Ramp Duration cell. HYSYS 
adjusts the SP from 100 to 150 linearly over the 10 minute 
interval.
SetPoint Options Group
In the past the PID controllers implemented an automatic 
setpoint tracking in manual mode, in other words, the value of 
the setpoint was set equal to the value of the PV when the 
controller was placed in manual mode. This meant that upon 
switching, the values of the setpoint and PV were equal, and 
therefore there was an automatic bumpless transfer. 
In the present controller setup, the Sp (Manual) option allows 
PV tracking, by selecting the No Tracking radio button, when the 
controller is in manual mode. However, when the controller is 
switched into the automatic mode from manual, there is an 
internal resetting of the controller errors to ensure that there is 
an instantaneous bumpless transfer prior to the controller 
recognizing a setpoint that is different from the PV. 
If the Track PV radio button is selected than there would be an 
automatic setpoint tracking. 
The Local Sp option allows you to disable the tracking for the 
local setpoint when the controller is placed in manual mode. You 
can also have the local setpoint track the remote setpoint by 
selecting the Track Remote radio button.
The Remote Sp option allows you to select either the Use% 
radio button (for restricting the setpoint changes to be in 
percentage) or Use Pv units radio button (for setpoint changes 
to be in PV units).
• Use%. If this radio button is selected, then the 
controller reads in a value in percentage from a remote 
source and uses the PV range to calculate the new 
setpoint.5-114
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Logical Operations 5-115
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Th• Use Pv units. If this radio button is active, then the 
controller reads in a value from a remote source, and is 
used as the new setpoint. The remote sources setpoint 
must have the same units as the controller PV.
An example, it is desired to control the flowrate in a stream with 
a valve. A PID controller is used to adjust the valve opening to 
achieve the desired flowrate, that is set to range between 
0.2820 m3/h and 1.75 m3/h. A spreadsheet is used as a remote 
source for the controller setpoint. A setpoint change to 1 m3/h 
from the current Pv value of 0.5 m3/h is made. The spreadsheet 
internally converts the new setpoint as m3/s (in other words, 1/
3600 = 0.00028 m3/s) and pass it to the controller, which 
converts it back into m3/h (in other words, 1 m3/h). The 
controller uses this value as the new setpoint. If the units are 
not specified, then the spreadsheet passes it as 1 m3/s, which is 
the base unit in HYSYS, and the controller converts it into 3600 
m3/h and pass it on to the SP field as the new setpoint. Since 
the PV maximum value cannot exceed 1.75m3/h, the controller 
uses the maximum value (1.75 m3/h) as the new setpoint.
Sp and Op Limits Group
This group enables you to specify the output and setpoint limits. 
The output limits ensure that a predetermined minimum or 
maximum output value is never exceeded. In the case of the 
setpoint, the limits enforce an acceptable the range of values 
that could be entered via the interface or from a remote source.
When the Enable Op Limits in Manual Mode checkbox is 
selected, you can enable the set point and output limits when in 
manual mode.
Algorithm Selection Group
In the Algorithm Selection group, you can select one of the 
three available controller update algorithms: 
• PID Velocity Form
• PID Positional Form (ARW = Anti-Reset Windup)
• PID Positional Form (noARW)
• PID Manual Loading5-115
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ThVelocity or Differential Form
In the velocity or differential form, the controller equation is 
given as:
where:  
u(t) = controller output and t is the enumerated sampling 
instance in time
u(t-1) = value of the output one sampling period ago
Kc, Ti, and Td = controller parameters
h = sampling period
Positional Form
In the positional form of the algorithm, the controller output is 
given by:
Here it is important to handle properly the summation term 
associated with the integral part of the control algorithm. 
Specifically, the integral term could grow to a very large value in 
instances where the output device is saturated, and the PV is 
still not able to get to the setpoint. For situations like the one 
above, it is important to reset the value of the summation to 
ensure that the output is equal to the limit (upper or lower) of 
the controller output. As such, when the setpoint is changed to a 
(5.17)
The velocity or differential form of the controller should be 
applied when there is an integral term. When there is no 
integral term a positional form of the controller should be 
used.
(5.18)
u t( ) u t 1–( ) Kc e t( ) e t 1–( ) 1
Ti
----e t( )h
Td
e( t( ) 2e t 1–( ) e t 2–( ) )+–
h
-------------------------------------------------------------------
+
+
–+=
u t( ) Kc e t( ) 1
Ti
---- e i( )h
i 1=
n
∑ Td
e t( ) e t 1–( )–( )
h
--------------------------------------+ +=5-116
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Logical Operations 5-117
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Thregion where the controller can effectively control, the controller 
responds immediately without having to decrease a summation 
term that has grown way beyond the upper or lower limit of the 
output. This is referred to as an automatic resetting of the 
control integral term commonly called anti-reset windup.
In HYSYS, both algorithms are implemented as presented above 
with one key exception, there is no derivative kick. This means 
that the derivative part of the control algorithm operates on the 
process variable as opposed to the error term. As such the 
control equation given in Equation (5.19) is implemented as 
follows:
Manual Loading Station
In the manual loading station algorithm the output, u(t), is 
equal to the input y(t).
Here the setpoint plays no role in the algorithm, instead 
whatever the percent input value is going into the controller, the 
output follows the same percent value. As in the case of the 
other control algorithms the output is bounded by an upper and 
lower limit of 100% and 0.0% respectively.
OP Override
The INIT box usually indicates that the OP value displayed on 
the controller has been back-calculated either from another 
controller or a selector block.The OP value is determined based 
on the Kc term and the PV range specified on the controller.
(5.19)
(5.20)
In Manual mode, you can set the OP like regular PID.
In Auto mode, the OP equals to PV based on PV range.
u t( ) u t 1–( ) Kc e t( ) e t( )– 1
Ti
----e kh( ) Td
pv– 2pv t 1–( ) pv t 2–( )–+( )
h
--------------------------------------------------------------------------+ ++=
u t( ) y t( )=5-117
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ThA controller can show INIT under two circumstances: 
• The controller is the master controller in a master-slave 
configuration and the slave controller is not in cascade 
mode. The OP for the master controller is back 
calculated, allowing for bumpless transfer when 
switching controller modes. The INIT message serves to 
notify the user that the OP is being calculated elsewhere. 
• The controller is one of two (or more) controllers feeding 
their respective OPs into a selector block. The controller 
whose OP has not been selected will show INIT to 
indicate that its OP has been calculated by the selector. 
Again, this is to facilitate a bumpless transfer when the 
selected controller changes.
The unselected PID Controller/Selector Block calculates the 
Output as follows:
The unselected PID is tracking the selector output so that it can 
be reselected by the Selector Block when the PV reaches a 
certain range. The output of the unselected PID is calculated 
based on the current output of the selector:
Autotuner Page
The autotuner function provides tuning parameters for the PID 
controller based on gain and phase margin design. The 
autotuner itself can be viewed as another controller object that 
has been embedded into the PID controller. The autotuner is 
based on a relay feedback technique, and by default 
incorporates a relay with hysteresis (h). 
The figure below shows an example of a relay with an amplitude 
(d) and hysteresis (h) is plotted on a graph of Output u(t) 
(5.21)
(5.22)
OPcontroller OPselector Kc
SP PV–
PVRange
------------------------⎝ ⎠
⎛ ⎞ 100%×–=
OPPID OPselector ΔMove+=5-118
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Thversus Error Input into the relay e(t) plot. 
This type of relay is a double-valued nonlinearity, sometimes 
referred to as having memory. In other words, the value of the 
output depends on the direction that the process error is 
coming. Relays are quite common in automation and control, 
and this technique for tuning PID controllers has been around at 
least 10 years now (see Cluett and Goberdhansingh, 
Automatica, 1992). The technique has a strong theoretical base 
and in general works well in practice but it is not a panacea.
The PID controller parameters that are obtained from the 
autotuner are based on a design methodology that makes use of 
a gain margin at a specified phase angle. This design is quite 
similar to the regular gain and phase margin methodology 
except that it is more accurate since the relay has the ability to 
determine points in the frequency domain accurately and 
quickly. Also, the relay experiment is controlled and does not 
take a long time during the tuning cycle.
The Autotuner page allows you to specify the autotuning 
parameters.
 Figure 5.725-119
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ThThe page contains two groups:
• Autotuner Parameters. Contains the parameters 
required by the Autotuner to calculate the controller 
parameters.
• Autotuner Results. Displays the resulting controller 
parameters. You have the option to accept the results as 
the current tuning parameters
Autotuner Parameters Group
In this group, you can specify the controller type by selecting 
the PID or PI radio button for the Design Type. In the present 
autotuner implementation there are four parameters that the 
you must specify which are as follows: 
 Figure 5.73
Parameter Range
Ratio (Ti/Td) (Alpha)
Gain ratio (Beta)
Phase angle (Phi) 
Relay hysteresis (h)
Relay amplitude (d)
3.0 α 6.0≤ ≤
0.10 β 1.0≤ ≤
30° φ 65°≤ ≤
0.01% h 5.0%≤ ≤
0.5% d 10.0%≤ ≤5-120
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ThAutotuner Results Group
This group displays the results of the autotuner calculation, and 
allows you to accept the results as the current controller setting. 
The Start Autotuner button activates the tuning calculation, 
and the Stop Autotuning button abort the calculations. 
After running the autotuner, you have the option to accept the 
results either automatically or manually. Selecting the 
Automatically Accept checkbox sets the resulting controller 
parameters as the current value instantly. If the Automatically 
Accept checkbox is inactive, you can specify the calculated 
controller parameters to be the current setting by clicking the 
Accept button.
An example, while a case is running in a dynamic simulation, 
change the controller mode to either Manual or Automatic. On 
the Autotuner page, select the Design Type and specify the 
tuning parameters (or use the default values). Click the Start 
Autotuner button and wait for the Autotuner to display the 
results. To accept the results and copy them in the Current 
Tuning group on the Configuration page, click the Accept button.
IMC Design Page
The IMC Design page allows you to use the internal model 
control (IMC) calculator to calculate the PID parameters based 
In the present version of the software there are default 
values specified for the PID tuning. Before starting the 
autotuner, you must ensure that the controller is in the 
manual or automatic mode, and the process is relatively 
steady.
If you move the cursor over the tuning parameters field, the 
Status Bar displays the parameters range.
HYSYS suggest using the auto tuning results as a guideline 
and should not be treated as a catholicon. It is recommended 
to specify the Autotuning parameters to suit your process 
requirement.5-121
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Thon a specified model of the process one is attempting to control.
The IMC method is quite common in most of the process 
industries and has a very solid theoretical basis. In general, the 
performance obtained using this design methodology is superior 
to most of the existing techniques for tuning PIDs. As such, 
when there is a process model available (first order plus delay) 
this approach should be used to determine the controller 
parameters. 
You must specify a design time constant, which is usually 
chosen as three times that of the measured process time 
constant. The IMC Design page has the following two groups: 
As soon as you enter the parameters in the IMC Design 
Parameters group, the controller parameters are calculated and 
displayed in the IMC PID Tuning group. You can accept them as 
the current tuning parameters by clicking the Update Tuning 
button.
 Figure 5.74
Group Description
IMC Design 
Parameters
Contains the parameters for the process model which 
are required by the IMC calculator.
• Process Gain
• Process Time Constraint
• Process Delay
• Design To
IMC PID Tuning Displays the PID controller parameters.5-122
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ThScheduling Page
The Scheduling page gives you the ability to do parameter 
scheduling. 
The parameter scheduling is quite useful for nonlinear processes 
where the process model changes significantly over the region 
of operation. The parameter scheduling is activated through the 
Parameter Schedule checkbox. You can use three different 
sets of PID parameters, if you so desire for three different 
regions of operation. The following regions of operation can be 
specified from the Selected Range drop-down list.
• Low Range
• Middle Range
• High Range
These regions of operations can be based either on the setpoint 
or PV of the controller. The ranges can also be specified, the 
default values are 0-33%, 33%-66%, and 66%-100% of the 
selected scheduling signal. 
You need to specify the middle range limit by defining the Upper 
and Lower Range Limits.
 Figure 5.75
The values of 0 and 100 cannot be specified for both the 
Lower and the Upper Range Limits.5-123
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ThAlarms Page
The Alarms page allows you to set alarm limits on all exogenous 
inputs to and outputs from the controller. 
The page contains two groups and one button:
• Alarm Levels
• Alarms
• Reset Alarm button
Alarm Levels Group
The Alarm Level group allows you to set, and configure the 
alarm points for a selected signal type. There are four alarm 
points that can be configured:
• LowLow
• Low
• High
• HighHigh
The alarm points should be specified in the descending order 
from HighHigh to LowLow points. You cannot specify the value 
of the Low and LowLow alarm points to be higher than the signal 
value. Similarly, the High and HighHigh alarm points cannot be 
specified a value lower than the signal value. Also, no two alarm 
points can have a similar value. In addition, you can specify a 
 Figure 5.765-124
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Thdeadband for a given set of alarms. This can be helpful in 
situations where the signal is “noisy” to avoid constant 
triggering of the alarm. If a deadband is specified, you have to 
specify the alarm points so that their difference is greater than 
the deadband. At present the range for the allowable deadband 
is as follows:
 of the signal range.
Alarms Group
The Alarms group display the recently violated alarm for the 
following signals:
Reset Alarm Button
When the deadband has been set, it is possible that an alarm 
status is triggered and the alarm does not disappear until the 
band has been exceeded. The Reset Alarm button allows the 
alarm to be reset when within the deadband.
An example, it is desired to control the flowrate through a valve 
within the operating limits. Multiple alarms can be set to alert 
you about increases or decreases in the flowrate. For the 
purpose of this example, you are specifying low and high alarm 
limits for the process variable signal. Assuming that the normal 
flowrate passing through the valve is set at 1.2 m3/h, the low 
alarm should get activated when the flowrate falls below 0.7 m3/
h. Similarly, when the flowrate increases to 1.5 m3/h the high 
The above limits are set internally and are not available for 
adjustment by the user.
Signal Description
PV Process Variable
OP Output
SP Setpoint
DV Disturbance Variable (this is available for the feedforward 
controller in the Future)
RS Remote Setpoint
0.0% deadband 1.5%≤ ≤5-125
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Thalarm should get triggered.
To set the low alarm, first make sure that the Pv Signal is 
selected in the Signal drop-down list. Specify a value of 0.7 m3/
h in the cell beside the Low alarm level. Follow the same 
procedure to specify a High alarm limit at 1.5 m3/h. If you want 
to re-enter the alarms, click the Reset Alarm button to erase all 
the previously specified alarms.
PV Conditioning Page
The PV Conditioning page allows you to simulate the failure of 
the controller input signal.
This page consists of three groups:
• PV Sampling Failure
• Sample and Hold PV
• Stream Temperature Filter
 Figure 5.775-126
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ThPV Sampling Failure Group
The PV Sampling Failure group consists of three radio buttons: 
None, Fixed Signal, and Bias. The options presented to you 
changes with respect to the radio button chosen.
• When the None radio button is selected, the property 
view is as seen in the figure above, with only the Actual 
PV and Failed PV values displayed. 
• When Fixed Signal radio button is selected, the PV 
Sampling Failure group appears as follows.
The Failed Input Signal To parameter allows you to fix 
the failed input signal using either the PV units or a 
Percentage of the PV range. 
• When the Bias radio button is selected the PV Sampling 
Failure group appears as follows.
The PV Sampling Failure group allows you to drift the 
input signal. The parameters allow you to bias the signal 
and create a drift over a period of time. To start the drift 
simply click the Start Drift button.
Sample and Hold PV Group
The Sample And Hold PV group allows you to take a PV sample 
and hold this value for a specified amount of time.
 Figure 5.78
 Figure 5.795-127
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ThStream Temperature Filter Group
The Stream Temperature Filter group allows you to calculate the 
temperature of a low flow rate stream by applying a first order 
transient filter with a user-specified ambient time constant.
By default, the Apply Filter checkbox is cleared. You can apply 
the temperature filter by selecting the Apply Filter checkbox. 
To set the conditions for the filter, you will need to specify the 
following:
• First Order Time Constant. First order exponential 
time constant applied to the filter when the flow rate is 
within the acceptable range (in other words, above the 
Cut Off Flow value). By default, the First Order Time 
Constant is 15 seconds. If the field is empty, or you enter 
a value of zero, then no filtering is applied.
• Ambient Time Constant. Time constant applied to the 
filter when the flow rate of a stream drops below the Cut 
Off Flow value. It determines how long it takes for the 
actual temperature of the stream to reach the ambient 
temperature. By default, the ambient time constant is 
3600 seconds. If the field is empty, or you enter a value 
of zero, the temperature value is calculated from the 
flash and no filtering is applied.
• Cut Off Flow. Switch-over point at which the 
temperature filter applies the ambient time constant in 
calculating the temperature of the stream. The Cut Off 
Flow value is expressed in molar flow, and the default 
value is 1e-5 kmol/s.
If the stream flow rate is above the Cut Off Flow value, the 
controller automatically switches back to the normal flash 
calculations which only apply the First Order Time Constant. The 
Ambient Time Constant is applied when the flow rate drops 
below the Cut Off Flow value with the temperature ramping to 
ambient over some slow periods.
 Figure 5.805-128
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ThSignal Processing Page
The Signal Processing page allows you to add filters to any 
signal associated with the PID controller, as well as test the 
robustness of any tuning on the controller.
This page is made up of two groups: Signal Filters and Noise 
Parameters. Both of these groups allows you to filter and test 
the robustness of the following tuning parameters:
• Pv
• Op
• Sp
• Dv
• Rs
To apply the filter, select the checkbox corresponding to the 
signal you want to filter. Once active you can specify the filter 
time. As you increase the filter time you are filtering out 
frequency information from the signal. It is possible to add a 
filter that makes the controller unstable. In such cases the 
controller needs to be returned. Adding a filter has the same 
effect as changing the process the controller is trying to control.
For example, if the signal is noisy, there is a smoothing 
effect noticed on the plot of the PV when the filter is applied.
Activating a Noise Parameter is done the same way as adding a 
 Figure 5.815-129
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Thfilter. However, instead of specifying a filter time you are 
specifying a variance. Notice that if a high variance on the PV 
signal is chosen the controller may become unstable. As you 
increase the noise level for a given signal you observe a some 
what random variation of the signal.
FeedForward Page
The FeedForward page enables you to design a controller that 
takes into account measured disturbances. 
The Disturbance Variable Source group allows you to select a 
disturbance variable, and minimum and maximum variables. 
The disturbance variable is specified by clicking the Select Dv 
button. This opens the Variable Navigator.
The FeedForward Parameters group allows you to set the 
Operating Mode for both the PID controller and the FeedForward 
controller and tune the controller.
All FeedForward controllers require a process model in order for 
the controllers to work properly. Presently HYSYS uses a model 
 Figure 5.82
To enable feedforward control you must select the Enable 
FeedForward checkbox.5-130
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Ththat results in a lead-lag process. Therefore, there are four 
parameters available.
The equation model for the FeedForward controller is as follows:
where:  
Kp = gain
 = time constant
d = deadtime or delay
Model Testing Page
The Model Testing page allows you to set the following 
parameters for generating data from the plant model.
• Signal Type offers two options.
- PRBS is simple to use for model identification.
- STEP is more recognized in practical process 
applications.
• Signal Variation Amplitude determines how much the 
output variables are changed to identify the model. The 
default value is 5%.
• Time Interval determines how often data points are 
recorded during the testing phase.
• Testing Time Length determines the total time period 
to apply the testing. The value should be larger than the 
time constant of the system.
Select the Enable Test check box in the Monitor table to 
perform the model testing when the integrator starts. 
Click Reset Test to reset the model testing back to the 
beginning.
After the testing is complete, click Save Test Result to save 
the testing results. The results will be saved as three files:
• *_sp.vec for SP
• *_pv.vec for PV
(5.23)G s( ) Kp
τ1s 1+( )e ds–
τ2s 1+
-------------------------------=
τ
5-131
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Th• *_op.vec for OP
Initialization Page
The Initialization page of the PID controller contains the same 
information as the one for the ratio controller. 
For more information on 
back initialization and 
saturation, refer to 
Section 5.4.3 - Ratio 
Controller.5-132
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ThMonitor Tab
A quick monitoring of the response of the Process Variables, 
Setpoint, and Output can be seen on the Monitor tab. This tab 
allows you to monitor the behaviour of process variables in a 
graphical format while calculations are proceeding. 
The Monitor tab displays the PV, SP, and Op values in their 
relevant units versus time. You can customize the default plot 
settings using the object inspection menu, which is available 
only when you right-click on any spot on the plot area.
The object inspection menu contains the following options:
 Figure 5.83
Item Description
Graph Control Opens the Graph Control Property View to 
modify many of the plot characteristics. 
Turn Off/On Cross 
Hair
Turns the cross hair either on or on.
Turn Off/On Vertical 
Cross Hair
Turns the vertical cross hair either on or on.
Turn Off/On 
Horizontal Cross Hair
Turns the horizontal cross hair either on or on.
Values Off/On Displays the current values for each of the 
variables, if turned on.
Copy to Clipboard Copies the current plot to the clipboard with the 
chosen scale size. 5-133
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ThA quick way to customize your plot is to use the Monitor 
Properties property view, which can be access by clicking the 
Properties button.
There are three group available on the Monitor Properties 
property view, which are described as follows:
• Data Capacity. Allows you specify the type and amount 
of data to be displayed. You can also select the data 
sampling rate.
• Left Axis. Gives you an option to display either the PV 
and SP or the Error data on the left axis of the plot. You 
can also customize the scale or let HYSYS auto scale it 
according to the current values.
• Right Axis. Gives you an option to either customize the 
right axis scale or let HYSYS auto scale it according to 
the current OP value.
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation.
Print Plot Prints the plot as it appears on the screen.
Print Setup Allows you to access the typical Windows Print 
Setup. The Windows Print Setup allows you to 
select the printer, the paper orientation, the paper 
size, and paper source.
Item Description
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-134
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Th5.4.5 MPC Controller
The “Model Predictive Control” (MPC) controller addresses the 
problem of controlling processes that are inherently multi-
variable and interacting in nature, in other words, one or more 
inputs affects more than one output.  
The MPC property view contains the following tabs:
• Connections
• Parameters
• MPC Setup
• Process Models
• Stripchart
• User Variables
 Figure 5.84
The current version of the MPC implementation does not 
handle the problem of processes with constraints - a future 
release is capable of handling that class of problems.5-135
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ThConnections Tab
The Connections tab is comprised of six objects that allow you to 
select the Process Variable Source, Output Target Object, and 
Remote SP. 
 Figure 5.85
Object Description
Name Contains the name of the controller. It can be edited 
by selecting the field and entering the new name.
Process Variable 
Source Object
Contains the Process Variable Object (stream or 
operation) that owns the variable you want to control. 
It is specified via the Variable Navigator.
Process Variable Contains the Process Variable you want to control.
Output Target 
Object
The stream or valve which is controlled by the MPC 
Controller operation 
Remote Setpoint 
Source
If you are using set point from a remote source, select 
the remote Setpoint Source associated with the Master 
controller
Select PV/OP/SP These three buttons open the Variable Navigator which 
selects the Process Variable, the Output Target Object, 
the Remote Setpoint Source respectively.
PV/OP/SP These three fields allow you to select a specific Process 
Variable, Output Target Object, and Remote Setpoint 
Source respectively.5-136
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ThProcess Variable Source
Common examples of PVs include vessel pressure and liquid 
level, as well as stream conditions such as flow rate or 
temperature.
To attach the Process Variable Source, click the Select PV 
button. Then select the appropriate object and variable 
simultaneously, using the Variable Navigator. The Variable 
Navigator allows you to simultaneously select the Object and 
Variable.
Remote Setpoint
The “cascade” mode of the controller no longer exits. Instead 
what is available now is the ability to switch the setpoint from 
local to remote. The remote setpoint can come from another 
object such as a spread-sheet or another controller cascading 
down a setpoint. In other words, a master in the classical 
cascade control scheme.
The Select Sp button allows you to select the remote source 
using the Variable Navigator.
Output Target Object
The Controller compares the Process Variable to the Setpoint, 
and produces an output signal which causes the manipulated 
variable to open or close appropriately.
The Process Variable, or PV, is the variable that must be 
maintained or controlled at a desired value.
A Spreadsheet cell can also be a Remote Setpoint Source.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-137
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ThSelecting the Output Target Object is done in a similar manner 
to selecting the Process Variable Source. You are also limited to 
objects supported by the controller and not currently attached 
to another controller.
The information regarding the control valve or control op port 
sizing is contained on a sub-view accessed by clicking the 
Control Valve or Control OP Port button found at the bottom 
of the MPC Controller property view.
Parameters Tab
The Parameters tab contains the following pages:
• Operation
• Configuration
• Advanced
• Alarms
The Output of the Controller is the control valve which the 
Controller manipulates in order to reach the set point. The 
output signal, or OP, is the desired percent opening of the 
control valve, based on the operating range which you define 
in the Control Valve property view.
The Control Valve button (at the bottom right corner of the 
logical operation property view) appears if the OP is a 
stream.
The Control OP Port button (at the bottom right corner of the 
logical operation property view) appears when the OP is not 
a stream and there a range of specified values is required.5-138
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ThOperation Page
The Operation page allows you to set the execution type, 
controller mode and depending on the mode, either SP or OP.
Mode Group
The Controller operates in any of the following modes:
• Off. The Controller does not manipulate the control 
valve, although the appropriate information is still 
tracked.
• Manual. Manipulates the Controller output manually.
• Automatic. The Controller reacts to fluctuations in the 
Process Variable and manipulates the Output according 
to the logic defined by the tuning parameters.
You can select where the signal from the controller is sent using 
the drop-down list in the Execution field. You have two 
selections:
• Internal. Confines the signals generated to stay within 
HYSYS.
• External. Sends the signals to a DCS, if a DCS is 
connected to HYSYS.
 Figure 5.86
The mode of the 
controller may also be set 
on the Face Plate, refer to 
Section 5.13.2 - 
Controller Face Plate 
for more information.5-139
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ThSps and Pvs Group
Displays the Setpoint (SP) and Process Variable (PV) for each of 
the controllers inputs. Depending on the Mode of the controller 
the SP can either be input by you or is determined by HYSYS.
Outputs Group
The Output (OP) is the percent opening of the control valve. The 
Controller manipulates the valve opening for the Output Stream 
in order to reach the set point. HYSYS calculates the necessary 
OP using the controller logic in all modes with the exception of 
Manual. In Manual mode, you may enter a value for the Output, 
and the Setpoint becomes whatever the PV is at the particular 
valve opening you specify. This can be done for all of the inputs 
to the controller.
Configuration Page
The Configuration page allows to specify the process variable, 
setpoint, and output ranges.
 Figure 5.875-140
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ThPV: Min and Max
For the Controller to become operational, you must:
1. Define the minimum and maximum values for the PV (the 
Controller cannot switch from Off mode unless PVmin and 
PVmax are defined).
2. Once you provide these values (as well as the Control Valve 
span), you can select the Automatic mode and give a value 
for the Setpoint.    
HYSYS converts the PV range into a 0-100% range, which is 
then used in the solution algorithm. The following equation 
is used to translate a PV value into a percentage of the 
range:
SP Low and High Limits
You can specify the higher and lower limits for the Setpoints to 
reflect your needs and safety requirements. The Setpoint limits 
enforce an acceptable range of values that could be entered via 
the interface or from a remote source. By default the PVs min 
and max values are used as the SPs low and high limits, 
respectively. 
Op Low and High Limits
You can specify the higher and lower limits for all the outputs. 
The output limits ensure that a predetermined minimum or 
maximum output value is never exceeded. By default 0% and 
100% is selected as a low and a high of limit, respectively for all 
the outputs.
HYSYS uses the current value of the PV as the set point by 
default, but you can change this value at any time.
Without a PV span, the Controller cannot function.
(5.24)PV %( )
PV PVmin–
PVmax PVmin–
-------------------------------------⎝ ⎠
⎛ ⎞ 100=5-141
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ThAdvanced Page 
The Advanced page contains the following three groups: 
The setpoint signal is specified in the Selected Sp Signal # 
field by clicking the up or down arrow button , or by typing 
the appropriate number in the field. 
Depending upon the signal selected, the page displays the 
respective setpoint settings.
When the Enable Op Limits in Manual Mode checkbox is 
selected, you can enable the set point and output limits 
when in manual mode.
Group Description
Setpoint 
Ramping
Allows you to specify the ramp target and duration.
Setpoint Mode Contains the options for setpoint mode and tracking, 
as well as the option for remote setpoint.
Setpoint Options Contains the option for setpoint tracking only in 
manual mode. 
 Figure 5.885-142
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ThSetpoint Ramping Group
The setpoint ramping function has been modified in the present 
MPC controllers. Now it is continuous, in other words, when set 
to on by clicking the Enable button, the setpoint changes over 
the specified period of time in a linear manner.
The Setpoint Ramping group contains the following two fields:
• Target SP. Contains the Setpoint you want the 
Controller to have at the end of the ramping interval. 
When the ramping is turn off, the Target SP field display 
the same value as SP field on the Configuration page.
• Ramping Duration.Contains the time interval you want 
to complete setpoint change in. 
Besides these two fields there are also two buttons available in 
this group:
• Enable. Activates the ramping process.
• Disable. Stops the ramping process.
While the controller is in ramping mode, you can change the 
setpoint as follows:
• Enter a new setpoint in the Target SP field.
• Enter a new setpoint in the SP field, on the Operation 
page.
Setpoint ramping is only available in Auto mode.
 Figure 5.89
Ramping Duration = RTSP
SP(t)
t t+RT Time
Target
SP
Controller Ramping5-143
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ThDuring the setpoint ramping the Target SP field shows the final 
value of the setpoint whereas the SP field, on the Operation 
page, shows the current setpoint seen internally by the control 
algorithm.
An example, if you click the Enable button and enter values for 
the two parameters in the Setpoint Ramping group, the 
Controller switches to Ramping mode and adjusts the Setpoint 
linearly (to the Target SP) during the Ramp Duration, see 
Figure 5.90. For example, suppose your current SP is 100, and 
you want to change it to 150. Rather than creating a sudden 
large disruption by manually changing the SP while in Automatic 
mode, click the Enable button and enter the SP of 150 in the 
Target SP input field. Make the SP change occur over, say, 10 
minutes by entering this time in the Ramp Duration field. HYSYS 
adjusts the SP from 100 to 150 linearly over the 10 minute 
interval. 
Setpoint Mode Group
You now have the ability to switch the setpoint from local to 
remote using the Setpoint mode radio buttons. Essentially, 
there are two internal setpoints in the controller, the first is the 
local setpoint where you can manually specify the setpoint via 
the property view (interface), and the other is the remote 
setpoint which comes from another object such as a 
spreadsheet or another controller cascading down a setpoint. In 
other words, a master in the classical cascade control scheme.
The Sp Local option allows you to disable the tracking for the 
local setpoint when the controller is placed in manual mode. You 
can also have the local setpoint track the remote setpoint by 
selecting the Track Remote radio button.
During ramping, if a second setpoint change has been 
activated, then Ramping Duration time would be restarted 
for the new setpoint.5-144
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ThThe Remote Sp option allows you to select either the Use% 
radio button (for restricting the setpoint changes to be in 
percentage) or Use Pv units radio button (for setpoint changes 
to be in Pv units).
• Use%. If the Remote Sp is set to Use%, then the 
controller reads in a value in percentage from a remote 
source, and using the Pv range calculates the new 
setpoint.
• Use Pv units. If the Remote Sp is set to Use Pv units, 
then the controller reads in a value from a remote source 
and sets a new setpoint. The remote source’s setpoint 
must have the same units as the controller Pv.
SetPoint Options Group
If the Track PV radio button is selected, then there is automatic 
setpoint tracking in manual mode, that sets the value of the 
setpoint equal to the value of the Pv prior to the controller being 
placed in the manual mode. This means that upon switching 
from manual to automatic mode the values of the setpoint and 
Pv were equal and, therefore, there was an automatic bumpless 
transfer. Also you have the option not to track the pv, by 
clicking the No Tracking radio button, when the controller is 
placed in manual mode. However, when the controller is 
switched into the automatic mode from manual, there is an 
internal resetting of the controller errors to ensure that there is 
an instantaneous bumpless transfer prior to the controller 
recognizing a setpoint that is different from the Pv. 
An example, it is desired to control the flowrate in a stream with 
a valve. A MPC controller is used to adjust the valve opening to 
achieve the desired flowrate, that is set to range between 
0.2820 m3/h and 1.75 m3/h. A spreadsheet is used as a remote 
source for the controller setpoint. A setpoint change to 1 m3/h 
from the current PV value of 0.5 m3/h is made. The spreadsheet 
internally converts the new setpoint as m3/s (1/3600 = 
0.00028 m3/s) and passes it to the controller, which reads the 
value and converts it back into m3/h (1 m3/h). The controller 
uses this value as the new setpoint. If the units are not 
specified, then the spreadsheet passes it as 1 m3/s, which is the 
base unit in HYSYS, and the controller converts it into 3600 m3/
h and passes it on to the SP field as the new setpoint. Since the 5-145
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ThPV maximum value cannot exceed 1.75m3/h, the controller uses 
the maximum value (1.75 m3/h) as the new setpoint.
Alarms Page
The Alarms page allows you to set alarm limits on all exogenous 
inputs to and outputs from the controller. The page contains two 
groups:
• Alarm Levels
• Alarms
Alarm Levels Group
The Alarm Level group allows you to set, and configure the 
alarm points for a selected signal type. There are four alarm 
points that could be configured:
• LowLow
• Low
• High
• HighHigh
The alarm points should be specified in the descending order 
from HighHigh to LowLow points. You cannot specify the value 
of the Low and LowLow alarm points to be higher than the signal 
 Figure 5.905-146
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Thvalue. Similarly, the High and HighHigh alarm points cannot be 
specified a value lower than the signal value. Also, no two alarm 
points can be specified a similar value. In addition, you can 
specify a deadband for a given set of alarms. This can be helpful 
in situations where the signal is “noisy” to avoid constant 
triggering of the alarm. If a deadband is specified, you have to 
specify the alarm points so that their difference is greater than 
the deadband. At present, the range for the allowable deadband 
is as follows:
 of the signal range.
Alarms Group
The Alarms group displays the recently violated alarm for the 
following signals:
An example, it is desired to control the flowrate through a valve 
within the operating limits. These limits can be monitored using 
the Alarms feature in MPC Controller. Multiple alarms can be set 
to alert you about increase or decrease in the flowrate. For the 
purpose of this example, you are specifying low and high alarm 
limits for the process variable signal. Assuming that the normal 
flowrate passing through the valve is set at 1.2 m3/h, the low 
alarm should get activated when the flowrate falls below 0.7 m3/
h. Similarly, when the flowrate increases to 1.5 m3/h the high 
alarm should get triggered.
To set the low alarm, first make sure that the Pv Signal is 
selected in the Signal drop-down list. Specify a value of 0.7 m3/
h in the cell beside the Low alarm level. Follow the same 
procedure to specify a High alarm limit at 1.5 m3/h. If you want 
The above limits are set internally and are not available for 
adjustment by the user.
Signal Description
PV Process Variable
OP Output
SP Setpoint
0.0% deadband 1.5%≤ ≤5-147
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Thto re-enter the alarms, click the Reset Alarm button to erase all 
the previously specified alarms.
Signal Processing Page
The Signal Processing page allows you to add filters to any 
signal associated with the MPC controller, as well as test the 
robustness of any tuning on the controller.
This page is made up of two groups:
• Signal Filters
• Noise Parameters
Both of these groups allow you to filter, and test the robustness 
of the following tuning parameters:
• Pv
• Op
• Sp
• Rs
To apply the filter select the checkbox corresponding to the 
signal you want to filter. Once active you can specify the filter 
time. As you increase the filter time you are filtering out 
frequency information from the signal. For example the signal is 
noisy, there is a smoothing effect noticed on the plot of the PV. 
 Figure 5.915-148
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ThNotice that it is possible to add a filter that makes the controller 
unstable. In such cases the controller needs to be returned. 
Adding a filter has the same effect as changing the process the 
controller is trying to control.
Activating a Noise Parameter is done the same way as adding a 
filter. However, instead of specifying a filter time you are 
specifying a variance. Notice that if a high variance on the PV 
signal is chosen the controller may become unstable. As you 
increase the noise level for a given signal you observe a some 
what random variation of the signal.
MPC Setup Tab
The MPC controller has a number of setup options available. 
These options are available on the Basic and Advanced pages of 
the Setup tab. In order to change any of the default values 
specified on these pages it is necessary to enable the MPC 
modifications checkbox. Whatever the option chosen, it is 
important to establish a sampling period (control interval) first. 
Specifically, the sampling period must be chosen to be 
consistent with the sampling theorem (see Shannon's 
Sampling Theorem). As such, it should be about 1/5 to 1/10 of 
the smallest time-constants. If the process is heavily dominated 
by process deadtime then the sampling period should be based 
on the deadtime. In situations where the process models are a 
mix of fast and slow process dynamics care should be taken in 
selecting the sampling period. A carefully designed MPC 
controller is an effective and efficient controller.5-149
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ThBasic Page
The Basic page divides the setup settings into MPC Control 
Setup and MPC Process Model Type groups. 
MPC Control Setup Group
In the MPC Control Setup group you are required to specify the 
following:
• Num of Inputs. Allows you to specify the number of 
process input. Up to a maximum of 12 process inputs can 
be specified. The default value is 1.
• Num of Outputs. Allows you to specify the number of 
process output. Up to a maximum of 12 process inputs 
can be specified. The default value is 1.
• Control Interval. Allows you to specify the control or 
sampling interval. The default value is 30 seconds.
 Figure 5.92
Anytime one of the MPC setting is changed, a new MPC 
object has to be created internally-this is automatically 
achieved by clicking on the Create MPC button.5-150
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ThMPC Process Model Type Group
You have the option to specify the model to be either Step 
response data or a First order model. If the Step response data 
radio button is selected, then a text file can be used to input the 
process model. The input file must follow a specific format in 
terms of inputs and outputs, as well as columns of data. The 
following is a description of the ASCII text file required for the 
input: 
The step response data is typically obtained either directly from 
plant data, or they are deducted from other so-called parametric 
model forms such as Discrete State-Space and Discrete Transfer 
Function Models.
 Figure 5.93
Number of 
inputs
Number of 
outputs
Number of 
columns
Step response 
length
Data5-151
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ThAdvanced Page
The Advanced page divides the setup settings into MPC Control 
Setup, MPC Process Model Type, and MPC Control Type groups. 
MPC Control Setup Group
In the MPC Control Setup group you are required to specify the 
following: 
 Figure 5.94
Anytime one of the MPC setting is changed, a new MPC 
object has to be created internally-this is automatically 
achieved by clicking on the Create MPC button.
Field Description
Num of 
Inputs
The number of process input. Up to a maximum of 12 
process inputs can be specified. The default value is 1.
Num of 
Outputs
The number of process output. Up to a maximum of 12 
process outputs can be specified. The default value is 1.
Control 
interval
The control or sampling interval. The default value is 30 
seconds.
Step Resp. 
length
The number of sampling intervals that is necessary to reach 
steady state when an input step is applied to the process 
model. The range of acceptable values are from 15 to 100. 
The default value is 50.5-152
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ThStep Response Length
This value represents the number of sampling intervals that is 
necessary to reach steady state when an input step is applied to 
the process model. You should consider all of the process 
models and the sampling interval when selecting step response 
length. At present, the maximum step response is limited to 100 
sampling intervals. Also, the fact that you are specifying the 
process models in terms of step response means that you are 
only considering stable processes in this MPC design.
Prediction Horizon and Control Horizon
The prediction horizon represents how far into the future the 
controller makes its predictions, based on the specified process 
model. The prediction horizon is limited to the length of the step 
response, and should be greater than the minimum process 
model delay. A longer prediction horizon means that the 
controller looks further into the future when solving for the 
controller outputs. This may be better if the process model is 
accurate. In general, you want to take full advantage of the 
process model by using longer predictions.
The control horizon is the number of control moves into the 
future the controller considers when making its predictions. In 
general, the larger the number of moves, the more aggressive 
Prediction 
Horizon
Allows you to specify how far into the future the predictions 
are made when calculating the controller output. The 
Prediction Horizon should be less than or equal to the Step 
Response Length. The default value is 25.
Control 
horizon
The number of control moves into the future that are made 
to achieve the final setpoint. A small control horizon 
generally means a less aggressive controller. The Control 
Horizon should be less than or equal to the Prediction 
Horizon. The default value is 2.
Reference 
trajectory
The time constant of a first order filter that operates on the 
true setpoint. A small reference trajectory lets the 
controller see a pure step as the setpoint is changed. The 
default value is 1.
Gamma_U/
Gamma_Y 
The positive-definite weighting functions, which are 
associated with the optimization problem that is solved to 
produce the controller output every control interval. The 
value of Gamma_U and Gamma_Y should be between 0 
and 1. The default value is 1.
Field Description5-153
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Ththe controller is. As a rule of thumb a control horizon of less 
than 3 is used quite often.
Sampling Interval and reference trajectory
Once you have determined the control interval, other 
parameters like reference trajectory can be chosen. This value 
affects the reference setpoint of the predictions used by the MPC 
problem when solving for the control outputs. Essentially, the 
reference trajectory represents the time constant of a first order 
filter that operates on the true setpoint. Hence, a very small 
value for the reference trajectory implies that the setpoint used 
in the MPC calculations are close to the actual setpoint. The 
minimum value for the reference trajectory that can be selected 
is 1second. 
One of the problems that could arise in setting this value “too 
large” is that the final setpoint reference value, which is used in 
the predictions, would not be seen by the control algorithm in a 
given iteration. Therefore, it is important that the reference 
trajectory value be chosen such that the time constant is 
smaller than the smallest time constant of the user specified 
process model set. At present, there is a limit placed on the 
reference trajectory that is based on the sampling interval and 
the maximum step-response. However, you should use the 
process model set as a guide when selecting this value.
In the present version the limits for the reference trajectory is 
as follows:
MPC Process Model Type Group
You have the option to specify the model to be either Step 
response data or First order model. If the Step response data is 
selected, then a text file can be used to input the process model. 
The input file must follow a specific format in terms of inputs 
and outputs, as well as columns of data, as shown in Figure 
5.94. 
(5.25)1 Reference Trajectory 15 Sampling  Interval×≤ ≤5-154
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ThMPC Control Type Group
This group allows you to select the MPC Control Algorithm that is 
used by the controller. At Present, the only option available for 
selection is the MPC Unconstrainted (No Int). This algorithm 
does not consider constraints on either controlled and 
manipulated variables.
Process Models Tab
The Process Models tab allows you to either view the step 
response data, or specify the first order model parameters.
Basic Page
Step Response Data
If the Step response data radio button is selected on the MPC 
Setup tab, the Process Model tab displays the Model Step 
Response matrix.
 Figure 5.955-155
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ThDepending on the number of inputs (i) and outputs (o) the 
system’s dynamics matrix should be an  matrix. The number 
of process models is equal to the number of outputs or 
controlled variables. If the Step response data is selected, then 
the First order model parameters fields are greyed out. 
First Order Model
If the First order model is selected on the MPC Setup tab, the 
Process Model table appears.
You can specify the first order model parameters for each of the 
process models, as follows: 
1. Select the input and output variable number in the Input # 
and Output # selection field by clicking the up or down 
arrow button , or by typing the appropriate number in the 
field. 
2. Depending upon the input and output variable selected, the 
relevant process model appears.
3. Then specify the process gain (Kp), process time constant 
(Tp) and delay for the selected process model in the 
available matrix. 
4. Repeat step# 1-2 for the remaining process models.
5. Then click the Update Step Response button to calculate 
the step response data for the process models.
You cannot modify the model step response data on the 
Process Model tab.
i o×5-156
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ThAdvanced Page
The Advanced page lists all of the Process Models, and their 
associated tuning parameters in table.
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
 Figure 5.96
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-157
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Th5.4.6 DMCplus Controller
The DMCplus Controller engine runs in Aspen DMCplus Online. 
HYSYS communicates to DMCplus using the DMCplus API. You 
are required to have the following licenses to run DMCplus in 
HYSYS:
• DMCplus Link
• DMCplus Online
• Cim-IO Kernel
• ACO Base
The figure below shows the HYSYS and DMCplus connection. 
HYSYS works like a Real Plant. 
The DMCplus Desktop allows you to configure the models. Each 
DMCplus Controller requires a Model File (MDL) and a Controller 
Configuration File (CCF) to operate properly with the Aspen 
DMCplus. 
• The MDL file determines the size of the control problem 
and all the dynamic relationships between each 
independent and dependent variables. 
 Figure 5.97
You must install DMCplus Online and DMCplus Desktop for 
the DMCplus Controller to operate properly. 
• DMCplus Online is required to run the DMCplus 
Controller.
• DMCplus Desktop allows you to configure the model 
used by the DMCplus Controller.
Refer to the Aspen 
Manufacturing Suite 
Installation Guide for 
information on installing 
DMCplus Online and 
DMCplus Desktop.
For information on adding 
the DMCplus Controller, 
refer to Section 5.4.1 - 
Adding Control 
Operations.5-158
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Th• The CCF file determines where the input and output 
parameters for the controller will reside, which optional 
capabilities will be used, and the values assigned to all of 
its parameters such as limits, switches, and tuning. 
HYSYS can generate the MDL file automatically or record the 
independent and dependent variable in the collection files (CLC), 
which contains model testing data. The data in the CLC files are 
used by the DMCplus Model to create the MDL file. The MDL file 
is then used by the Aspen DMCplus Build to create a CCF file.
You can add the DMCplus Controller to an existing HYSYS 
simulation case or to a new HYSYS simulation case that you 
have created.  
The DMCplus property view contains the following tabs:
• Connections
• Model Test
• Operation
• Stripchart
• User Variables
 Figure 5.98
If the DMCplus Controller is not loaded, it appears in yellow 
in the HYSYS flowsheet. The status bar on the DMCplus 
Controller property view will also appear in yellow and 
indicate that the DMCplus has not been loaded.5-159
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ThThe DMCplus Controller property view also contains an Enable 
DMCplus checkbox at the bottom right corner. This checkbox 
allows you to enable or disable the DMCplus Controller. When 
the Enable DMCplus checkbox is disabled, the model testing 
features can be enabled in the Model Test tab.
Connections Tab
The Connections tab allows you to define and edit the 
Controlled, Manipulated and Feed Forward variables for the 
plant model. You can specify the name of the DMCplus 
Controller in the Controller Name field. 
You have to select the Enable DMCplus Modifications 
checkbox to add and edit the Controlled, Manipulated, and Feed 
Forward variables.
 Figure 5.99
When editing the Controlled and Manipulated variables in the 
DMCplus Model, ensure that the variable order is the same as 
in HYSYS. 5-160
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ThControlled Variable (CV)
You must specify a controlled variable for the DMCplus 
Controller. The controlled variables are the dependent variables 
that will be controlled by the DMCplus controller. 
The CV table contains the stream or operation that owns the 
variable you want to control. The stream or operation is 
specified using the Select Input property view, which appears 
when you click the Add CV button or Insert CV button. 
• The Add CV button adds the stream or operation after 
the last defined stream or operation in the table. 
• The Insert CV button adds the stream or operation 
before the currently selected stream or operation in the 
table.
You can select the appropriate object and variable 
simultaneously using the Select Input property view.  
 Figure 5.100
 Figure 5.101
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information on the 
Select Input property 
view.5-161
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ThManipulated Variable (MV)
You must specify a manipulated variable for the DMCplus 
Controller. The manipulated variables are the independent 
variables that will be manipulated by the DMCplus controller. 
The MV table contains the stream or operation which is 
controlled by the controller operation. 
• The Add MV button adds the stream or operation after 
the last defined stream or operation in the table. 
• The Insert MV button adds the stream or operation 
before the currently selected stream or operation in the 
table.
The stream or operation is specified using the Select Object 
property view, which appears when you click the Add MV button 
or Insert MV button.
When you add a stream to the MV table the Control Valve button 
is enabled. 
 Figure 5.102
 Figure 5.103
Refer to Section 5.4.7 - 
Control Valve for more 
information.5-162
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ThFeed Forward (FF)
You can add the Feed Forward variables if needed. 
The variable takes into account measured disturbances which 
you can view on the Feed Forward page of the Operation tab. 
You can add the Feed Forward variables using the Select Input 
property view similar to when you are adding a controlled 
variable. 
• The Add FF button adds the stream or operation after the 
last defined stream or operation in the table. 
• The Insert FF button adds the stream or operation before 
the currently selected stream or operation in the table.
The Feed Forward variables are used as independent variables 
in the DMCplus Model, and they cannot be manipulated by the 
DMCplus Controller. 
 Figure 5.1045-163
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ThModel Test Tab
The Model Test tab allows you to set up the DMCplus Controller 
for model testing. The Model Test page is the only page 
available on this tab.
The following table lists and describes the objects available in 
the Model Test tab:
 Figure 5.105
Object Description
Model Test Setting group
Test Signal Type cell Enables you to select the signal type for the 
DMCplus model test. There are two types of signal 
to choose from:
• PRBS is simple to use for model 
identification.
• STEP is more recognized in practical process 
applications.
Control/Sampling 
Time Interval cell
Enables you to specify the amount of time 
between recorded data points during the testing 
phase.
TTSS cell Enables you to specify the total time period 
available for the model testing. The value should 
at least be larger than the setting time of the 
system.5-164
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ThAuto Test checkbox Enables you to toggle between activating or 
deactivating the Auto Test option.
This option performs test for each of the selected 
Manipulated and Feed Forward variables one by 
one. The test results are used to generate an MDL 
file (which contains the DMCplus controller 
model).
If this checkbox is clear, you need to manually 
save the testing data to CLC files.
Conf. Ramp button Enables you to access the Configure Ramp 
Response property view. 
The Configure Ramp Response property view 
enables you to select the ramp type for each CV 
tag using the drop-down list available under the 
Ramp Type column. There are three types of 
ramp type to choose from:
• non-ramp
• ramp
• pseudo ramp
The Conf. Ramp button is only available if you 
selected the Auto Test option.
Auto test file root 
name field
Enables you to specify the location and name of 
the testing data files containing the auto test 
results and the date and time when the test was 
performed.
This field is only available if the Auto Test 
checkbox is selected.
Epsilon icon
Enables you to access the File Selection for Saving 
Test results property view and select the location 
to save the test result files.
This icon is only available if the Auto Test 
checkbox is selected.
Monitor table
Time left cell Displays the amount of time left in the model 
testing.
Current Interval cell Displays the current interval value during the 
model testing calculation.
Object Description5-165
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ThTotal Intervals cell Displays the total number of intervals required to 
complete the model testing.
Ready cell Displays an icon to indicate whether the selected 
model is ready for testing:
• Red cross  indicates the model is not 
ready.
• Green checkmark  indicates the model is 
ready for testing.
Enable Test cell Enables you to activate the model testing when 
the Start Test button is clicked.
Model Test Help icon Enables you to access the help property view that 
displays the steps required to develop the 
DMCplus controller.
Start Test button Enables you to first reset the test and then start 
the model testing.
Continue Test button Enables you to continues the last test if it has not 
been finished.
Stop Test button Enables you to stop the model testing before the 
test is complete
Select tag to apply the testing signal table
No. column Displays an integer number for each MV and FF 
variables in the DMCplus controller.
MV & FF Tag column Displays the name of the MV and FF variables in 
the DMCplus controller.
If a Feed Forward variable (FF) is a dependent (or 
calculated) variable, HYSYS cannot perform the 
test at the default/current setting.
Selected column Contains checkboxes that enable you to toggle 
between selecting or ignoring the variables for the 
test.
By default, all the Manipulated variables (MV) and 
Feed Forward variables (FF) are selected to apply 
the test signal.
Tested column Display the status of the variable, whether it has 
been tested or not, during the testing process.
Step Up column Contains checkboxes that enable you to toggle 
between step up testing or step down testing for 
each variable.
By default, the checkboxes are set to step up.
Amplitude column Enables you to specify the percentage value of 
testing signal amplitude for each variable.
By default, the signal amplitude is set at 1.00%.
Reset Test button Enables you to reset the model testing back to the 
beginning.
Object Description5-166
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ThPerforming DMCplus Model Testing
After selecting the controlled, manipulated, and feed forward 
variables, data needs to be generated from the plant model to 
develop the controller model. 
Follow the steps below to develop the controller model:
1. From the Model Testing Setting group, select the test setting 
parameters.
• In the Test Signal Type drop-down list, select STEP or 
PRBS. 
• In the Control/Sampling Time Interval cell, specify 
the time used to determine how often the data points are 
recorded during the testing phase.
• In the TTSS cell, specify the total time period during 
which to apply the testing. 
• In the Auto Test cell, use the checkbox to toggle 
between activating or deactivating the Auto Test option.
• Click the Conf. Ramp button to access the Configure 
Ramp Response property view. In the Configure Ramp 
Response property view, select the ramp characteristic/
option for each CV data using the drop-down list under 
the Ramp Type column.
• In the Auto test file root name field, specify the 
location and name for the generated testing data files. 
This field is only available if the Auto Test checkbox is 
selected.
2. The Select tag to apply the testing signal table contains 
several options to configure the variable to be tested.
Save Test Results 
button
Enables you to save the test data results in a *.clc 
file or a set of *.rec files.
Load DMC Controller 
button
Enables you to load and run the configured 
DMCplus controller model in the HYSYS simulation 
case.
This button is disabled if you do not have the 
configuration (.ccf) and model (.mdl) files in the 
correct directory.
It is recommended that the default setting in the Select tag 
to apply the testing signal table be modified by advance 
users for special case.
Object Description5-167
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Th3. In the Monitor table, select the Enable Test checkbox, to 
automatically activate the model testing when the Start 
Test button is clicked.
4. Click the Start Test button to start the testing.
When the Time left field displays zero, the testing is 
finished.
• If you had selected the Auto Test option, you can skip 
steps #5 to #6 because HYSYS will automatically 
generate an MDL file.
• If you did not select the Auto Test option, you have to 
manually save the test results in a file.
5. Click the Save Test Result button, and save the testing 
results to a *.clc file or a set of *.rec files.
The CLC or REC file(s) can be processed by the Aspen 
DMCplus Model to generate a MDL file.
Before you start the testing, ensure that all the related slave 
PID Controllers are set to the remote mode.
 Figure 5.1065-168
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Th6. Start the Aspen Model application, load the saved data and 
build the DMCplus model (*.mdl). 
In the DMCplus Model you will import the Collect file (*.clc) 
to vectors by saving the project first and then adding the 
CLC file.
If HYSYS has already generated the MDL file, you can still 
import the file into the DMCplus Model to review the 
generated model.
The MDL file determines the size of the control problem and 
all the dynamic relationships between each independent and 
dependent variables. 
 Figure 5.107
When adding the independent (MV) and dependent (CV) 
variables to a case, ensure that the order you are adding the 
variables is the same as on the Connections tab in HYSYS.
Refer to the DMCplus 
Desktop manual for 
details.5-169
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Th7. Start the Aspen Build application and build the DMCplus 
configuration file (*.ccf).
The CCF file determines where the input and output 
parameters for the controller will reside, which optional 
capabilities will be used, and the values assigned to all of its 
parameters such as limits, switches, and tuning.
8. Open the app folder in the DMCplus Online installation 
directory.
9. Create a folder with the controller name (for example 
DMC_100) and copy the *.mdl and *.ccf files into the 
folder. 
10.Return to HYSYS program.
11.Click the Load DMCplus Controller button. You should now 
be able to run the simulation using the newly created 
DMCplus Controller.
You can set the low and high variable limits for MVs and CVs 
(similar to setpoint range). 
 Figure 5.108
The DMCplus Controller requires that the DMCplus Online 
and DMCplus Desktop programs are installed. Refer to the 
Aspen Manufacturing Suite Installation Guide for information 
on installing DMCplus Online and DMCplus Desktop.
Refer to the DMCplus 
Desktop manual for 
details.
For information on setting 
the low and high variable 
limits, refer to the 
Operation Page section.5-170
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ThOperation Tab
The Operation Tab contains the following pages:
• Operation
• FF Variable
Operation Page
The Operation page allows you to set the controller mode and 
the low/high limit parameters.
DMCplus uses these low/high parameters to optimize the 
controlled variable (CV) and manipulated variable (MV) 
setpoints (steady state target) based on its tuning parameters.
All DMCplus Controllers created can be viewed using the 
DMCplus GUI. The DMCplus GUI provides more functionality 
on using the DMCplus Controller. 
 Figure 5.1095-171
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ThThe CV SS target is similar to the MPC Controller setpoint 
except:
• In MPC controller, you specify the CV SS target value.
• In DMCplus controller, you specify the lowest and highest 
setpoint values, and DMCplus calculates the CV SS target 
value based on the provided range.
The Update CCF File button enables you to export any update 
configuration results from the Operation page into the *.ccf 
file.
The Set Default Low/High Parameters button enables you to 
populate the CV and MV parameters with default values (refer to 
the table below):
The CV and MV SS targets are fixed, if the low/high limit values 
are the same.
Mode
The DMCplus Controller operates in any of the following modes:
• Off. The DMCplus Controller does not manipulate the 
control valve, although the appropriate information is 
still tracked.
• Manual. Manipulates the DMCplus Controller output 
manually. In the Manual mode you can enter a value for 
the Manipulated Variable (MV).
• Automatic. The DMCplus Controller reacts to 
fluctuations in the Controlled Variable (CV) and 
manipulates the Manipulated Variable (MV) according to 
the DMCplus algorithm.
For CV:
Low Limit = current value
High Limit = current value
For MV:
Low Limit = 0
High Limit = highest value limited by the variable span
For more information on 
the MPC Controller, refer 
to Section 5.4.5 - MPC 
Controller.5-172
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ThThe mode of the controller may also be set on the Face Plate.  
FF Variable Page
The Feed Forward Variable page allows you to view the 
controller measured disturbance. 
Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
On the Face Plate, you can also view the current value of the 
CV and MV. You cannot change the low/high limit using the 
Face Plate. 
The Feed Forward Variable page will only show the Feed 
Forward value if the Feed Forward variable has been added 
on the Connections tab.
 Figure 5.110
Refer to Section 5.13.2 
- Controller Face Plate 
for more information.
Refer to the section on 
the Feed Forward (FF) 
for more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.5-173
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ThUser Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
5.4.7 Control Valve
The information shown on the Control Valve property view is 
specific to the associated valve. For instance, the information for 
a Vapour Valve is different than that for an Energy Stream. 
To access the Control Valve property view, click the Control 
Valve button located at the bottom right corner of the controller 
operation property view.
FCV for a Liquid/Vapour Product 
Stream from a Vessel
The FCV property view for a material stream consists of two 
groups:
• Valve Parameters
• Valve Sizing
The Control Valve button appears if the OP is a stream.
 Figure 5.111
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-174
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ThThe Valve Parameters group contains flowrate information about 
the stream with which the Control Valve is associated. 
The Valve Sizing group is usually part of the property view that 
requires specification. This group contains three fields, which 
are described in the table below:
The Minimum and Maximum flow values define the size of the 
valve. To simulate a leaky valve, specify a Minimum flow greater 
than zero. The actual output flow through the Control Valve is 
calculated using the OP signal (% valve opening):
For example, if the Controller OP is 25%, the Control Valve is 
25% open, and is passing a flow corresponding to 25% of its 
operating span. In the case of a liquid valve, if the Minimum and 
Maximum flow values are 0 and 150 kgmole/h, respectively, the 
actual flow through the valve is 25% of the range, or 37.5 
kgmole/h.
FCV for Energy Stream
The FCV property view that appears is dependent on the type of 
duty stream selected. There are two types of duty streams: 
• Direct Q duty consists of a simple power value (in other 
words, BTU).
• Utility Fluid takes the duty from a utility fluid (in other 
words, steam) with known properties.
Field Description
Flow Type The type of flow you want to specify:
• molar flow
• mass flow
• liquid volume flow
• actual volume flow
Min. Flow The Minimum flow through the control valve.
Max. Flow The Maximum flow through the valve.
(5.26)Flow OP %( )
100
----------------- Maximum Minimum–( ) Minimum+=5-175
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ThThe type of Duty Source specified can be changed at any time 
by clicking the appropriate radio button in the Duty Source 
group.
Direct Q Duty Source
This is the Flow Control Valve (FCV) view, when the Duty Source 
is set to Direct Q in the Duty Source group.
The Attached Stream and Controller appear in the upper left 
corner of the property view in the Control Attachments group. 
The specifications required by the property view are all entered 
into the Direct Q group. In this group, Setpoint (SP) appears, 
and you may specify the minimum (Min. Available) and 
maximum (Max. Available) cooling or heating available.
 Figure 5.1125-176
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ThFrom Utility Fluid Duty Source
As with the Direct Q Duty Source, the attached stream, and 
controller appear in the upper left corner of the property view. 
There are several Utility Fluid Parameters, which can be 
specified in the Utility Properties group:
Available to Controller checkbox. When you make the 
controller connections, and move to the Control Valve property 
view (by clicking the Control Valve button on the PID Controller 
property view), the Available to Controller checkbox is 
 Figure 5.113
The application of the Utility Fluid information is dependent 
on the associated operation.
Parameter Description
UA The product of the local overall heat-transfer 
coefficient and heat-transfer surface area.
Holdup The total amount of Utility Fluid at any time. The 
default is 100 kgmole.
Flow The flowrate of the Utility Fluid. 
Min and Max Flow The minimum and maximum flowrates available for 
the Utility Fluid.
Heat Capacity The heat capacity of the Utility Fluid.
Inlet and Outlet 
Temp 
The inlet and outlet temperatures of the Utility Fluid.
T Approach The operation outlet temperature minus the outlet 
temperature of the Utility Fluid. 5-177
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Thautomatically selected. HYSYS assumes that because you 
installed a new controller on the valve, you probably want to 
make it available to the Controller.
5.4.8 Control OP Port
To access the Control OP Port property view, click the Control 
OP Port button at the bottom right corner of the control 
operation property view. 
The following table lists and describes the common options in 
the Control OP Port property view:
The Control OP Port button appears when the OP is not a 
stream and a range of specified values is required.
 Figure 5.114
Object Description
Attached Object cell Displays the name of the output target object 
attached to the controller.
Attached Controller 
cell
Displays the name of the controller attached to the 
output target object.
Current Value cell Displays the current value of the output target 
object variable.
Minimum Value cell Enables you to specify the minimum value for the 
output target object variable.
Maximum Value cell Enables you to specify the maximum value for the 
output target object variable.5-178
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Th5.5 Digital Point
The Digital Point is an On/Off Controller. You specify the Process 
Variable (PV) you want to monitor, and the output (OP) stream 
which you are controlling. When the PV reaches a specified 
threshold value, the Digital Point either turns the OP On or Off, 
depending on how you have set up the Digital Point.
5.5.1 Digital Point Property 
View
There are two ways that you can add a Digital Point to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Digital Pt.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Digital Control Point icon.
The PV is optional; if you do not attach a Process Variable 
Source, the Digital Point operates in Manual mode.
Digital Control Point icon5-179
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ThThe Digital Point property view appears.
5.5.2 Connections Tab
The Process Variable Source and Output Target are both 
optional connections. No error is shown when these are not 
connected nor does an error appear in the Status List Window. 
 Figure 5.115
 Figure 5.116
Click the 
Control Valve 
button to view 
the Control 
Valve property 
view.
Click the Face 
Plate button to 
view the Controller 
Face Plate.
The Process 
Variable object 
(stream or 
operation) that 
owns the variable 
you want to control.
The Process 
Variable you 
want to control.
The Output object 
is the stream, 
which is controlled 
by the Digital Point.5-180
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ThThe optional connections feature allows the controller to be in 
Manual mode, and have its OPState imported into a 
Spreadsheet and used in further calculations in the model. This 
configuration can only be used for Manual mode. 
To run the controller in Automatic mode, you require a Process 
Variable Source input. With only the input connected, the Digital 
Point acts as a digital input indicator. With both the input and 
output specified the Digital Point can be used to determine its 
state from its PV and then take a discrete action.
To specify the controller input, use the Select PV button to 
access the Variable Navigator property view, which allows you 
to simultaneously target the PV Object and Variable. Similarly, 
use the Select OP button to choose the Output Target. 
5.5.3 Parameters Tab
The Parameters tab provides three different modes of operation:
• Off
• Manual
• Auto
For each of these modes the Parameters tab is made up of a 
number of groups: Output, Manual/Auto Operational 
Parameters, and Faceplate PV Configuration.
Off Mode
When Off mode is selected, you cannot adjust the OP State. 
Notice that if you turn the controller Off while running the 
simulation, it retains the current OP State (Off or On). Thus, 
turning the Controller off is not necessarily the same as leaving 
the Controller out of the simulation. 
The flow of the OP Output is manipulated by the Digital Point 
Controller.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-181
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ThOnly the Output group, displaying the current OP State, is 
visible when in the Off mode.
Manual Mode
When Manual mode is selected you can adjust the OP State from 
the Faceplate or this tab. Two groups are visible when in this 
mode: Output and Manual Operation Parameters.
The Output group allows you to toggle the OP state on and off. 
The Operational Parameters group allows you to select one of 
the three options described in the table below.
 Figure 5.117
 Figure 5.118
Option Description
Latch Holds the current OP State to what is specified in the 
Output group.
Pulse On Allows the OP State to Pulse On for a specified period and 
fall back to the Off state.
Pulse Off Allows the OP State to Pulse Off for a specified period and 
fall back to the On state.5-182
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ThAuto Mode
When Auto mode is selected, HYSYS automatically operates the 
Digital Point, setting the OP State Off or On when required, 
using the information you provided for the Threshold and OP 
Status. Three groups are visible when in this mode: Output, 
Auto Operational Parameters, and Faceplate PV Configuration.
Since HYSYS is automatically adjusting the controller, the 
Output group simply displays the OP State. Like Manual mode, 
the Auto Operation Parameters group allows you to select one of 
the three options:
• Latch
• Pulse On
• Pulse Off
 Figure 5.119
 Figure 5.120
Allows you to specify 
the duration of the 
pulse.5-183
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ThWhen Latch is selected the following parameters appear.
For both the Pulse On and Pulse Off options the parameters are 
the same as the Latch option. However the pulse options both 
require you to specify a Pulse Duration.
The Face Plate PV Configuration group allows you to specify the 
minimum and maximum PV range. This is the range shown on 
the controllers Face Plate.
Threshold and Dead Band for Latch
For the Latch option, the OP (output) switches states (on or off) 
when the PV (Process Variable) value reaches the set point 
value. The set point value is accompanied with an adjustable 
differential gap or dead band value, this value allows small 
deviations to occur in the PV value without triggering changes to 
the OP state.
Parameter Description
PV The actual value of the PV (Process Variable).
Threshold The value of the PV which determines when the controller 
switches the OP on or off.
Higher 
Deadband
Allows you to specify the upper deviation of the threshold 
value.
Lower 
Deadband
Allows you to specify the lower deviation of the threshold 
value.
OP On/Off 
when
Allows you to set the condition when the OP state is on or 
off. 
 Figure 5.121
For more information 
regarding how Digital 
Point logical operation 
determines when to turn 
the OP state on or off, 
refer to Threshold and 
Dead Band for Latch 
section.
For more information 
regarding how Digital 
Point logical operation 
determines state of the 
Pulse (on or off), refer to 
Threshold and Dead 
Band for Pulse section.5-184
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ThThe following is an example of how the Latch option operates. 
Assume you have a Digital Point operation with the following 
parameters: 
The following situations illustrates when the OP is turned on or 
off.
• Initial State. If PV value starts at 70 and OP is off, the 
OP stays off until the PV value rises above or to equal 
145, than OP is turned on.
• Intermediate State. If PV value rises and falls above 
value 80 and OP state is already on, then OP remains on.
• Intermediate State. If PV value falls below or equal 
value 80, OP is turned off.
The above situation is the same for Latch option with OP is on 
when PV <= Threshold, with the reverse effect. In other words, 
Parameter Value
Threshold 100
Higher dead band 45
Lower dead band 20
OP is on when PV >= Threshold
 Figure 5.122
• Red line indicates the path of the OP vs. time.
• Blue line indicates the path of the PV vs. time.
If PV value starts at 150 and OP state is off, then OP remains 
off until the PV value falls below 80 and rises above 145, 
after PV reaches or rises above 145 the OP state is turned 
on.
Dead band
OP
PV
Time5-185
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5-186 Digital Point
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ThOP is turned on when PV value passes through the lower dead 
band value, and OP is turned off when PV value passes through 
the higher dead band value.
Threshold and Dead Band for Pulse
For the Pulse option, the OP (output) remains in a state (on or 
off) until the PV (Process Variable) value reaches the set point 
value, then OP switches state briefly and returns back to its 
default state (like a pulse). The set point value is accompanied 
with an adjustable differential gap or dead band value, this 
value allows small deviations to occur in the PV value without 
triggering the OP state pulse.
The following is an example of how the Pulse option operates. 
Assume you have a Digital Point operation with the following 
parameters:
Parameter Value
Pulse Off. The OP default state is off.
Threshold 100
Higher dead band 45
Lower dead band 20
Pulse ON/OFF when PV >= Threshold
Pulse Duration 2 seconds5-186
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ThThe following situations illustrates when the OP is turned on or 
off.
• If PV value starts at 70, the OP is off until the PV value 
rises to equal 145, than OP is on for 2 seconds.
• After OP state has pulsed on once, OP remains off if PV 
value rises and falls above the value 80.
5.5.4 Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
5.5.5 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
 Figure 5.123
• Red line indicates the path of the OP vs. time.
• Blue line indicates the path of the PV vs. time.
If PV value starts at 150, OP is off until the PV value falls 
below 80 and rises above 145, after PV reaches 145 the OP 
state is on for 2 seconds.
OP
PV
Time
OP turned on 
for 2 seconds
PV value falls below lower dead band.
Dead band
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-187
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Th5.5.6 Alarm Levels Tab
The Alarms tab allows you to set alarm limits for the controller. 
The Alarm Level group allows you to set and configure the alarm 
points for a selected signal type. There are four alarm points 
that can be configured:
• LowLow
• Low
• High
• HighHigh
The alarm points should be specified in the descending order 
from HighHigh to LowLow points. You cannot specify the value 
of the Low and LowLow alarm points to be higher than the signal 
value. Similarly, the High and HighHigh alarm points cannot be 
specified a value lower than the signal value. Also, no two alarm 
points can have a similar values. In addition, the user can 
specify a deadband for a given set of alarms. This can be helpful 
in situations where the signal is “noisy” to avoid constant 
triggering of the alarm. If a deadband is specified, you have to 
specify the alarm points so that their difference is greater than 
the deadband. At present the range for the allowable deadband 
is as follows:
 of the signal range.
The Alarm Status displays the recently violated alarm for each 
alarm point.
 Figure 5.124
The above limits are set internally and are not available for 
adjustment by the user!
0.0% deadband 1.5%≤ ≤5-188
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Th5.6 Parametric Unit 
Operation
The Parametric Unit operation allows selected unit operations, 
streams, and variables to be solved using a Parametric model. 
The main function of the Parametric model is to approximate an 
existing HYSYS model. To build the Parametric model, the 
Parametric Utility tool is required. 
The Parametric utility integrates Neural Network (NN) 
technology into its framework. A data file with the appropriate 
data can be used in place of the Parametric Utility.
Using a Parametric model with neural network capability to 
approximate a HYSYS model significantly improves the 
robustness of the model, reduces its calculation time, and 
improves the overall on-line performance. The accuracy of the 
model depends upon the data available and type of model being 
approximated.
In the flowsheet, the parametric unit operation essentially “pulls 
out” a collection of HYSYS unit operations and replaces them. 
Therefore, this unit operation can be thought of as a “black box” 
with inputs and outputs. When the flowsheet is solved, the 
Parametric model is used in place of the individual HYSYS unit 
operation models.
For more information on 
this utility, refer to 
Section 14.14 - 
Parametric Utility.5-189
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Th5.6.1 Parametric Unit 
Operation Property View
To add a Parametric Unit Operation to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Parametric 
Unit Operation.
4. Click the Add button. 
The Parametric Unit Operation property view appears. The 
property view has four tabs:
• Design
• Training
• Worksheet
• Validation
5.6.2 Design Tab
The Design tab contains the following pages:
• Connections
• Setup
• Notes
Connections Page
The Connections page allows the parametric unit operation to be 
connected with the information required for the Parametric 
model. This information can be found in either a Parametric 
Utility or a data file. This page always contains a Name field and 
Input Data group. The rest of the page is different depending on 
the selected Input Data type.
The Name field allows you to define a unique name for the unit 5-190
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Thoperation. The Input Data group allows you to define where the 
input data to the Parametric model is to be found. The rest of 
the property view is altered depending on the radio button 
selected. The options available are: 
• Use Utility Data
• Inputs from a Data File
Each of the radio buttons are described in the following sections.
Use Utility Data Radio Button
When the Use utility data radio button is selected, one 
additional group (Parametric/LP Utility Selection) and two 
additional buttons (Create Utility and View Utility) become 
available.
Parametric/LP Utility Selection Group
If any Parametric Utilities exist in the case, you can select one 
by clicking the Browse button. The Browse button opens the 
Select Parametric Utility property view, as shown in the 
following figure. 
Select the Parametric Utility to be used for the unit operation, 
and click OK.
 Figure 5.1255-191
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ThCreate Utility Button
If a Parametric Utility does not exist in the HYSYS case or if you 
want to create a new Utility, click the Create Utility button to 
creates one for use in the Parametric unit operation.
View Utility Button
To view the selected Parametric Utility, click the View Utility 
button.
Inputs from a Data File Radio Button
When using this option, the Parametric unit operation does not 
have to obtain the model parameter from a utility. Instead, an 
external data file can be used.
Data File Format Group
In the Data File Format group, you can select the format of 
information to be stored in the *.dat file.
• The format for the Row is:
input11, input21, input31, ...
output11, output21, output31, ...
input12, input22, input32, ...
output12, output22, output32, ...
• The format for the Column is:
Data File Selection Group
Clicking the Browse button allows you to navigate, and locate 
the data file that contains the required information for the 
Parametric model. The information in the file is comma 
delimited and is stored in a *.dat file.
input11 input12 output11 output12
input21 output22 output21 output22
input31 input32 output31 output32
... ... ... ...5-192
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ThInput Units from Data File Field
Using the drop-down list, the units used in the data file can be 
defined.
Modeled Streams for Input–Output Group
The input and output streams that are being modeled can be 
selected from the list of existing streams in the drop-down list. A 
new stream can be created and used in the Parametric unit 
operation by entering a new stream name in the appropriate 
cell.
View Data Button
The View Data button is available in both the Connections page 
and Setup page. Clicking the View Data button opens the Data 
Presentation property view.
In this property view, you can see the data from the *.dat file in 
graph format. The radio button and checkbox in the Plot column 
allow you to select which data set appears on the graph.
 Figure 5.1265-193
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ThYou can also specify the high and low limits for each data set, 
using the High Value and Low Value fields. When you specify the 
range of data set, the Parametric Unit Operation only takes the 
data within the range to use for training. So the High Value and 
Low Value fields allow you to discard any initial and end data 
values that may be inaccurate.
Setup Page
The appearance of this page, like the Connections page, is 
dependant on the radio button selected in the Input Data group 
on the Connections page. 
Use Utility Data Radio Button
When the Use Utility Data radio button is selected, the property 
view appears as shown in the figure below.
Available Unit Op Models from Utility Group
When the Use Utility Data radio button is selected on the 
Connections page, only one group is available on the Setup 
page. In this table, all unit operations that have a Parametric 
model in the selected Parametric Utility appear. The name of the 
unit operation, the status of the model activity, and the 
operation status of the unit operations are all displayed. The 
Model Activity can be chosen to be active or inactive by clicking 
 Figure 5.1275-194
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Ththe checkbox. When the model is inactive, it is only removed 
from the Parametric Utility.
Inputs from a Data File Radio Button
When the Inputs from a Data File radio button is selected, the 
property view appears as shown in the figure below.
The Setup page contains two groups:
• Data Mapping 
• Training Pair Status
Data Mapping Group
Two radio buttons are available in this group: Inputs and 
Outputs. The table below describes the properties displayed.
 Figure 5.128
Property Description
Number of Training 
Pairs
The number of data sets read in from the data file.
Data Point A specific data within the data file.
Mapped Variable The variable in the attached stream that is 
associated to the data set.
Variable Type The variable type of the data point, which is 
selected from the drop-down list.
Identifier Allows you to enter a unique name to identify the 
data points.5-195
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ThTraining Pair Status Group
Displays the individual training pairs, and indicates whether the 
pair contains bad data. If an ‘X’ appears, there is no bad data. If 
a checkmark appears, there is bad data in the data set.
Notes Page
The Notes page provides a text editor, where you can record 
any comments or information regarding the operation or to your 
simulation case in general.
5.6.3 Training Tab
The Training tab displays the training variables of the attached 
Parametric Utility.
There are four main objects in the Training tab:
• Connected Unit Operations. The number of unit 
operations connected to the Parametric unit operation 
appears in this field.
• Manipulated Variables. By selecting the Manipulated 
radio button, the manipulated variables in the Parametric 
model appear. 
The manipulated variables are the variables being 
modified in the Parametric Utility and obtained from the 
HYSYS PFD model simulation. The name of the variable 
appears, and the selected status is shown. You can select 
or deselect the variable for use in the parametric model 
by clicking the checkbox. The lower and upper values 
used for training are also displayed.
Low and High Value The minimum and maximum values in the data 
set.
Bad Variable Status If an ‘X’ appears, the data is good. If a checkmark 
appears, there is bad data in the data set.
Current Value The value used in the worksheet after training.
A training pair is defined as a set of input and output data.
Property Description
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.5-196
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Th• Observable Variables. By selecting the Observable 
radio button, the observable variables in the Parametric 
model appear. 
The observable variable is the same as the Observable 
variable in the Parametric Utility. Observable variables 
are the HYSYS variables whose values are known and 
used as training data when calculating the Parametric 
model. The name of the variable appears and the 
selected status is shown. You can select or deselect the 
variable for use in the Parametric model calculation by 
clicking the checkbox. The lower and upper values for 
training are also displayed.
• Train Button. Clicking the Train button initializes the 
Parametric Utility training engine to determine the 
parameters for the Parametric model. 
The Parametric model approximates the HYSYS model in 
the sense that, given the same values of the training 
input variables, the values of the output variables of the 
Parametric model must be close to the values from the 
HYSYS model.     
5.6.4 Worksheet Tab
The Worksheet tab displays the various Conditions, Properties, 
and Compositions of the unit operations, streams, and variables 
that are using the Parametric model. From here you can use the 
neural network instead of the flowsheet, and where the training 
pairs have been used from a file, see how the neural network 
has modeled the operation from which your training pairs were 
generated. These objects appear as different pages on the tab.
5.6.5  Validation Tab
The final step before using the Neural Network is to validate the 
results. In the validation process, a new set of input data is 
given to both the HYSYS model and the Neural Network.
It is important to realize that there are no methods for 
training neural networks that can “magically” create 
information that is not contained in the training data. The 
neural network model is only as good as its training data.
For more information on 
the Workbook, refer to 
Section 7.23 - 
Workbook in the HYSYS 
User Guide.5-197
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ThThe Validation options are described below:
5.7 Recycle
The capability of any flowsheet simulator to solve recycles 
reliably and efficiently is critical. HYSYS has inherent 
advantages over other simulators in this respect. It has the 
unique ability to back-calculate through many operations in a 
non-sequential manner, allowing many problems with recycle 
loops to be solved explicitly. For example, most heat recycles 
can be solved explicitly (without a Recycle operation). Material 
recycles, where downstream material mixes with upstream 
material, require a Recycle operation.
The Recycle installs a theoretical block in the process stream. 
The stream conditions can be transferred either in a forward or 
backward direction between the inlet and outlet streams of this 
block. In terms of the solution, there are assumed values and 
calculated values for each of the variables in the inlet and outlet 
streams. Depending on the direction of transfer, the assumed 
value can exist in either the inlet or outlet stream. For example, 
if the user selects Backward for the transfer direction of the 
Temperature variable, the assumed value is the Inlet stream 
temperature and the calculated value is the Outlet stream 
temperature.
The following steps take place during the convergence process:
1. HYSYS uses the assumed values and solves the flowsheet 
Button Description
PM runs Runs the Parametric model to generate validation data 
based on the Parametric model.
HYSYS runs Runs the HYSYS model to generate validation data based 
on the HYSYS model.
View Results 
Table...
Allows the viewing of validation data in table format. 
Compares the HYSYS validation data with Parametric 
model data. 
View Results 
Graph...
Allows the viewing of validation data in graphical format. 
Compares the HYSYS validation data with Parametric 
model data.5-198
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Tharound the recycle.
2. HYSYS then compares the assumed values in the attached 
streams to the calculated values in the opposite stream.
3. Based on the difference between the assumed and 
calculated values, HYSYS generates new values to overwrite 
the previous assumed values.
4. The calculation process repeats until the calculated values 
match the assumed values within specified tolerances.
5.7.1 Recycle Property View
There are two ways that you can add a Recycle to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Recycle.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Recycle icon. 
Recycle icon5-199
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5-200 Recycle
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ThThe Recycle property view appears. 
5.7.2 Connections Tab
The Connections tab contains the following pages:
• Connections
• Notes
Connections Page 
The Connections page consists of the four fields:
• Name. The name of the Recycle operation.
• Inlet. Holds the inlet stream, which is the latest 
calculated recycle; it is always a product stream from a 
unit operation.
• Outlet. Contains the outlet stream, which is the latest 
assumed recycle; it is always a feed stream to a unit 
operation.
 Figure 5.129
Object Description
Continue button Enables you to run the calculation after the maximum 
iteration has been reached.
Recycle 
Assistant button
Enables you to access the Recycle Assistant property 
view. 
Refer to Section 5.7.9 - 
Recycle Assistant 
Property View for more 
information.5-200
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Th• Fluid Package. The fluid package associated to the 
operation can be selected by entering the fluid package 
name or using the drop-down list.
Notes Page
The Notes page provides a text editor, where you can record 
any comments or information regarding the operation or to your 
simulation case in general.
5.7.3 Parameters Tab
The Parameters tab contains the following pages:
• Variables
• Numerical
If RefSYS is installed, the Parameters tab has a Convergence 
page.
Variables Page
HYSYS allows you to set the convergence criteria factor for each 
of the variables and components listed. The sensitivities values 
you enter actually serve as a multiplier for HYSYS internal 
 Figure 5.130
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.5-201
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5-202 Recycle
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Thconvergence tolerances. 
 Figure 5.1315-202
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ThThe internal absolute tolerances, except flow which is a relative 
tolerance, are shown in the table below. 
For example, the internal tolerance for temperature is 0.01 and 
the default multiplier is 10, so the absolute tolerance used by 
the Recycle convergence algorithm is 0.01*10 = 0.1. Therefore, 
the assumed temperatures and the calculated temperature must 
be within 0.1°C (where C is the internal units) of each other if 
the Recycle is to converge. HYSYS always convert the values 
entered to the internal units before performing calculations.
A multiplier of 10 (default) is normal, and is recommended for 
most calculations. Values less than 10 are more stringent; that 
is, the smaller the multiplier, the tighter the convergence 
tolerance.
HYSYS Internal Tolerances
Variable Internal Tolerance
Vapour Fraction 0.01
Temperature 0.01
Pressure 0.01
Flow 0.001**
Enthalpy 1.00
Composition 0.0001
Entropy 0.01
**Flow tolerance is relative rather than absolute
The internal Vapour Fraction tolerance, when multiplied by 
the recycle tolerance, is 0.1 which appears to be very loose. 
However, in most situations, if the other recycle variables 
have converged, the vapour fraction in the two streams are 
identical. The loose Vapour Fraction tolerance is critical for 
close-boiling mixtures, which can vary widely in vapour 
fraction with minimal difference in other properties.
It is not required that each of the multipliers be identical. For 
example, if you are dealing with ppm levels of crucial 
components, you can set the Composition tolerance 
multiplier much tighter (smaller) than the others.5-203
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5-204 Recycle
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ThThe Transfer Direction column allows you to select the transfer 
direction of the variable. There are three selections:
• not to transfer
• transfer forward
• transfer backward
Not Transferred option can be used if you only want to transfer 
certain stream variables. For example, if you only want to 
transfer P, T composition and flow, the other variables could be 
set to Not Transferred.
When you select the Take Partial Steps checkbox, the Recycle 
operation takes calculation steps on any variables whenever the 
calculations are possible. When you clear the checkbox, the 
Recycle operation waits until all of the inlet stream flowing into 
the operation is complete before performing the next calculation 
step. The default setting for this checkbox is clear.
In addition to converging on physical properties basis, the 
Recycle operation also converges on individual component 
tolerances. The components in the recycle stream are 
automatically added to the Recycle logical operation. When you 
select the Use Component Sensitivities checkbox, the single 
composition sensitivities value is automatically overridden by 
the individual component sensitivities values and the Recycle 
operation takes calculation steps on each value when applicable. 
The default setting for this checkbox is inactive. Once you select 
the Use Component Sensitivities checkbox, the tolerances for 
each component in the recycle stream are listed in the table. By 
default, the sensitivities value is set at 10.00 for each 
component. Any changes that you make to the sensitivities 
value are automatically saved.5-204
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ThNumerical Page
The Numerical page contains the options related to the Wegstein 
Acceleration Method.
This method is used by the Recycle to modify the values it 
passes from the inlet to outlet streams, rather than using direct 
substitution. 
The table below describes the parameters on the Numerical 
page. 
 Figure 5.132
Numerical 
Parameters
Description
Mode You can choose between Nested or Simultaneous mode by 
selecting the respective radio button. The default mode is 
Nested. 
Acceleration You can choose between two methods of acceleration:
• Wegstein. Ignores interactions between variables 
being accelerated.
• Dominant Eigenvalue. Includes interactions 
between variables being accelerated. Further, the 
Dominant Eigenvalue option is superior when dealing 
with non-ideal systems or systems with strong 
interactions between components.
Maximum 
Iterations 
The number of iterations before HYSYS stops (the default is 
10). You can continue with the calculations by clicking the 
Continue button at the bottom of the Recycle property 
view.
Iteration 
Count 
The number of iterations before an acceleration step is 
applied to the next iteration (default is 0).
Flash Type The Flash method to be implemented by the Recycle unit 
op.
Refer to the Type of 
Recycle section for more 
information.5-205
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5-206 Recycle
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ThType of Recycle
There are two choices for the type of Recycle:
• Nested
• Simultaneous
The Nested option results in the Recycle being called whenever 
it is encountered during the calculations. In contrast, the 
Simultaneous option causes all Recycles to be invoked at the 
same time once all recycle streams have been calculated. If 
your flowsheet has a single Recycle operation, or if you have 
multiple recycles which are not connected, use the Nested 
option (default). If your flowsheet has multiple inter-connected 
recycles, use the Simultaneous type.
There are several additional points worth noting about the 
Recycle:
• When the Recycle cannot be solved in the number of 
iterations you specify, HYSYS stops. If you decide that 
the problem may converge with more iterations, simply 
click the Continue button. The Recycle initializes the 
iteration counter and continues until a solution is found 
or it again runs out of iterations.
• If your problem does not converge in a reasonable 
number of iterations, there are probably constraints in 
your flowsheet which make it impossible to solve. In 
particular, if the size of the recycle stream keeps 
growing, it is likely that the flowsheet does not permit all 
Acceleration 
Frequency
The value in this field is the number of steps to go before 
putting in acceleration. The lower the value, the more often 
variables get accelerated.
Q maximum/
Q minimum
Damping factors for the acceleration step (defaults are 0 
and -20).
Acceleration 
Delay
This delays the acceleration until the specified step (default 
is 2).
The Calculation Level for a Recycle (accessed under Main 
Properties) is 3500, compared to 500 for most streams and 
operations. This means that the Recycle is solved last among 
unknown operations. You can set the relative solving order 
of Recycles by modifying the Calculation Level.
Numerical 
Parameters
Description5-206
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Thof the material entering the flowsheet to leave. An 
example of this occurs in gas plants when you are trying 
to make a liquid product with a low vapour pressure and 
a vapour product which must remain free of liquids even 
at cold temperatures. Often, this leaves no place for 
intermediate components like propane and butane to go, 
so they accumulate in the plant recycle streams. It is 
also possible that the tolerance is too tight for one or 
more of the Recycle variables and cannot be satisfied. 
This can readily be determined by examining the 
convergence history, and comparing the unconverged 
variable deviations with their tolerances.
• The logical operations (such as the Recycle, Adjust and 
Controller) are different from other operations in that 
they actually modify the specifications of a stream. As a 
result, if you remove any of these operations, the outlet 
stream specifications remain. Thus, nothing in the 
flowsheet is “forgotten” for these operations. You can 
Delete or Ignore a Recycle when you want to make 
flowsheet modifications, but do not want to invoke the 
iterative routines.
• Tolerance settings are important to a successful Recycle 
solution. This is especially true when multiple recycles 
are involved. If there is no interaction among the 
recycles, or if they are inter-connected and are being 
solved simultaneously, tolerance values can be identical 
for all Recycles if desired. However, if the Recycles are 
nested, tolerances should be made increasingly tighter 
as you go from the outermost to the innermost Recycle. 
Without this precaution, the outside Recycle may not 
converge.
Maximum Number of Iterations
When HYSYS has reached the maximum number of iterations, a 
warning message appears stating that the Recycle failed to 
converge in the specified number of iterations. You can then 
choose whether or not to continue calculations.
If you are starting a new flowsheet, use a small number of 
Maximum Iterations, such as 3. Once it is evident that the 
calculations are proceeding well, the count can be increased. 
The iterations required depend not only on the complexity of 
The Monitor tab provides a history of the Recycle 
calculations.5-207
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Thyour flowsheet, but also on your initial estimate and the 
convergence tolerances you use.
Damping Factors - Qmax and Qmin
The Wegstein acceleration method uses the results of previous 
iterations in making its guesses for the recycle stream variables. 
Assumed values are calculated as follows:
where:  
X = assumed value
 Y = calculated value
 n = iteration number
 Q = acceleration factor
HYSYS determines the actual acceleration (Q) to apply based on 
the amount of change between successive iterations. The values 
for Qmax and Qmin set bounds on the amount of acceleration 
applied. Note from the equation that when Q = 0, direct 
replacement is used. When Q is negative, acceleration is used. 
When Q is positive and smaller than 1, damping occurs.
Iteration Count
The Iteration Count is the number of Recycle iterations before 
an acceleration step is applied when calculating the next 
assumed recycle value. The default count is 3; after three 
iterations (assuming the Acceleration Delay is less than 3), the 
assumed and calculated recycle values are compared and the 
Wegstein acceleration factor is determined and applied to the 
(5.27)
If you are finding that your Recycle is still oscillating, even 
with the Iteration Count set to ensure direct replacement, 
you can input a slightly larger value for Qmax to damp the 
direct replacement.
Xn 1+ QXn 1 Q–( )Yn+=5-208
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Logical Operations 5-209
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Thnext assumed value. When the acceleration factor is not being 
used (in all iterations up to the Iteration Count), the next 
assumed value is determined by direct replacement.
Notice that Acceleration Delay takes precedence over the 
Iteration Count. This means that for an Acceleration Delay value 
of x, the initial x iterations use direct replacement, even if the 
Iteration Count is set to less than x. The x+1 iteration uses the 
acceleration after which the Iteration Count applies.
Although acceleration generally works well for most problems, in 
some cases it may result in over-correction, oscillation, and 
possibly non-convergence. Examples of this type of problem 
include highly-sensitive recycles and multiple recycle problems 
with strong interactions among recycles. In cases such as these, 
direct replacement may be the best method for all iterations. To 
eliminate the use of acceleration, simply set the Iteration Count 
(or Acceleration Delay) to a very high number of iterations (for 
example, 100) which is never reached. In the rare instance 
where even direct replacement causes excessive over-
corrections, damping is required. Use the set of parameters 
discussed below to control this.
Acceleration Delay
The Acceleration Delay parameter delays the acceleration until 
the specified step. This delay applies to the initial set of 
iterations and once the specified step is reached the Iteration 
Count is applied. That is to say no acceleration is performed 
until the delay value is reached and after that iteration the 
 Figure 5.133
iterations
Recycle 
Iterations Begin
N  I  I  I  I
AD - Acceleration Delay
I - Iteration Count
if I  AD then N = AD+1 else if I > AD then N = I≤5-209
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5-210 Recycle
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Thacceleration is applied according to the Iteration count. The 
default is specified as 2 but now it can be specified to any value. 
For example, if the 'delay' is set to 5 and the Iteration Count is 3 
then the first 5 iterations use direct replacement and the sixth 
uses acceleration then after every third iteration the 
acceleration step is applied.
Convergence Page
The Convergence page contains information about transferring 
and converging petroleum properties across the recycle. On this 
page, you can 
• individually set each property as an active specification 
during the recycle convergence
• adjust the tolerance for each property
• view the current value for each property
5.7.4 Worksheet Tab
The Worksheet tab displays the various Conditions, Properties, 
and Compositions of the Feed and Product streams.
5.7.5 Monitor Tab
The Monitor tab contains the following pages:
• Setup
• Tables
Note: The Convergence page only appears when RefSYS is 
installed.
For more information 
refer to Section 1.3.10 - 
Worksheet Tab.5-210
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Th• Plots
The Setup page allows you to specify which variables you want 
to view or monitor. To view a variable, select the View 
checkbox corresponding to the variable of interest.
The Tables page and Plots page display the convergence 
information as the calculations are performed in tabular and 
graphical format respectively. The inlet value, outlet value, and 
variable are shown, along with the iteration number.
This is illustrated in the following figure.
 Figure 5.134
 Figure 5.135
Tables page Plots page5-211
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5-212 Recycle
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Th5.7.6 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
5.7.7 Calculations
HYSYS provides a very simple means of solving recycle 
problems, and its interactive nature provides a high degree of 
control and feedback to the user as to how the solution is 
proceeding. 
The Recycle can be set up as a single unit operation to represent 
a single recycle stream in a process flowsheet, or a number of 
them can be installed to represent multiple recycles, 
interconnected or nested, as well as a combination of 
interconnected and nested recycle loops. Similar to the multi-
Adjust operation, the Recycle solves all the recycle loops 
simultaneously, if requested to do so.
The step-by-step procedure for setting up a recycle is as 
follows:
1. Make a guess for the assumed values in the stream attached 
to the recycle operation (temperature, pressure, flow rate, 
composition). The flow rate can generally be zero, but, 
In Dynamic mode, HYSYS ignores the Recycle operation. So 
in the case of the outlet stream, it is identical to the inlet 
stream.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-212
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Thobviously, better estimates results in faster convergence. 
2. Build your flowsheet until the calculated values in the 
connected streams can be determined by HYSYS.
3. Install the Recycle block.
5.7.8 Reducing Convergence 
Time
Selection of the recycle tear location is vitally important in 
determining the computer run time to converge the Recycle. 
Although the physical recycle stream itself is often selected as 
the tear stream, the flowsheet can be broken at virtually any 
location. In simulating a complex system, a number of factors 
must be considered. The following are some general guidelines:
• Choose a Tear Location to Minimize the Number of 
Recycles
Reducing the number of locations where the iterative 
process is required save on total convergence time. 
Choosing the location of the Recycle depends on the 
flowsheet topology. Attempt to choose a point such that 
specifying the assumed values defines as many streams 
downstream as possible. It generally occurs downstream 
of gathering points and upstream of distribution points. 
Examples include downstream of mixers (often mixing 
points where the physical recycle combines with the 
main stream), and upstream of tees, separators, and 
columns.
• Choose a Tear Location to Minimize the Number of 
Recycle Variables
Variables include vapour fraction, temperature, pressure, 
flow, enthalpy, and composition. Choose the tear stream 
so that as many variables as possible are fixed, thus 
effectively eliminating them as variables and increasing 
If the recycle is a feed to a tower, a reasonable estimate is 
needed to ensure that the column converges the first time it 
is run.
The outlet and inlet recycle streams must have different 
names.5-213
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Thconvergence stability. Good choices for these locations 
are at separator inlets, compressor aftercooler outlets, 
and trim heater outlets.
• Choose a Stable Tear Location
The tear location can be chosen such that fluctuations in 
the recycle stream have a minimal effect. For example, 
by placing the tear in a main stream, instead of the 
physical recycle, the effect of fluctuations are reduced. 
The importance of this factor depends on the 
convergence algorithm. It is more significant when 
successive substitution is used. Choosing stable tear 
locations is also important when using simultaneous 
solution of multi-recycle problems.
5.7.9 Recycle Assistant 
Property View
The Recycle Assistant property view enables you to find places 
to insert Recycle unit operation that make the simulation case 
convergent easily.
There are two other functionalities in the Recycle Assistant 
feature:
• Enables you to analyse the flowsheet to get suggested 
tear streams.
• Enables you to delete and add Recycle Unit Op in the 
Recycle Assistant’s interface. For the delete option, only 
one Recycle Unit op can be deleted at one time.
To access the Recycle Assistant property view, do one of the 
following:
• In the HYSYS menu bar, select the Tools | Recycle 
Assistant command.
• Open the Recycle operation property view, and click the 
Recycle Assistant button.
Avoid choosing tear streams which have variables 
determined by an Adjust operation.
The feature is only available in Steady State mode.5-214
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ThThe Recycle Assistant property view appears.
The options in the Recycle Assistant property view are split into 
the following tabs:
• Flowsheet Analysis
• Recycle Setup
 Figure 5.1365-215
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5-216 Recycle
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ThFlowsheet Analysis Tab
The Flowsheet Analysis tab enables you to add, modify, and 
delete recycle operations and analyse the flowsheet. 
 Figure 5.137
Object Description
Current Recycles and 
Tear Streams group
Displays two lists of all the recycles and associate 
tear streams available in the PFD.
Delete Recycle 
button
Enables you to delete the selected recycle 
operation in the list.
Suggested Tear 
Streams group
Displays a list of possible tear streams available in 
the PFD.
Add Recycle button Enables you to add a recycle to the selected tear 
stream in the list.
Rebuild button Enables you to modify and optimize the process 
flow diagram using the suggested tear streams 
and recycles.
Analyse Flowsheet 
button
Enables you to update the list of available tear 
stream in the PFD.5-216
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ThRecycle Setup Tab
The Recycle Setup tab enables you to modify the variable 
sensitivity of the selected recycle operation. 
 Figure 5.138
Object Description
Current Recycle Ops 
list
Displays the list of available recycle operations in 
the PFD.
Vapour Fraction cell Enables you to modify the vapour fraction 
sensitivity.
Temperature cell Enables you to modify the temperature sensitivity.
Pressure cell Enables you to modify the pressure sensitivity.
Flow cell Enables you to modify the flow rate sensitivity.
Enthalpy cell Enables you to modify the enthalpy sensitivity.
Composition cell Enables you to modify the composition sensitivity.
Entropy cell Enables you to modify the entropy sensitivity.
Using Component 
Sensitivities 
checkbox
Enables you to toggle between including or 
discarding the sensitivity values based on the 
components in the PFD.
Component table Enables you to modify the component sensitivity 
values for all the components in the PFD.
Current Values group Displays the same options available in the Variable 
Sensitivities table, except the variable values are 
taken from the selected recycle operation in the 
Current Recycle Ops list.5-217
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5-218 Selector Block
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Th5.8 Selector Block
The Selector Block is a multiple-input single-output controller, 
that provides signal conditioning capabilities. It determines an 
Output value based on a user-set Input function. For instance, if 
you want the maximum value of a specific variable for several 
Input streams to dictate the Output, you would use the Selector 
Block. A simple example would be where a Selector Control 
chooses the average temperature from several temperature 
transmitters in a Column, so that the Reboiler duty can be 
controlled based on this average.
5.8.1 Selector Block Property 
View
There are two ways that you can add a Selector Block to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Selector 
Block.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
Apply to Selection 
button
Enables you to apply the modified variable 
sensitivities values to the selected recycle 
operations in the Current Recycle Ops list.
Apply to All button Enables you to apply the modified variable 
sensitivities values to all the recycle operations in 
the PFD.
Object Description5-218
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Th2. Double-click the Selector Block icon. 
The Selector Block property view appears.
5.8.2 Connections Tab
The Connections tab consists of three objects described in the 
table below: 
 Figure 5.139
Objects Description
Selector 
Name
Contains the name of the Selector Block, which can be 
edited at any time.
Process 
Variable 
Sources
Contains the variables the Selector Block considers and 
inserted into the input function.
The Process Variables for the various inputs are targeted by 
clicking Add PV button, accessing the Variable Navigator. 
You can edit or delete any current PV by positioning the 
cursor in the appropriate row, and clicking the Edit PV or 
Delete PV buttons.
If you add a Variable whose type is inconsistent with the 
current Input Variables, HYSYS displays an error message. 
However, you are allowed to retain that Variable.
OP Target Contains the process variable, which is manipulated by the 
Selector Block. To select the OP Target click the Select OP 
button. This button also accesses the Variable Navigator.
Notice that it is not necessary for the Target Variable type 
to match the Input Variable type.
Selector Block icon
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.5-219
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Th5.8.3 Parameters Tab
The Parameters tab contains the following pages:
• Selection Mode
• Scaling Factor
Selection Mode Page
The Selection Mode page allows you to select the mode and 
parameters of the operation. 
 Figure 5.140
 Figure 5.141
When the Apply Unit Set 
checkbox is clear, the 
operation uses default 
internal HYSYS units (in 
other words, no real unit 
conversion) for the 
calculations.5-220
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ThIn the Mode group, you can choose from the following modes:
When the Apply Unit Set checkbox is selected, you can select a 
unit set and variable type for the calculations and output 
respectively. 
In the Parameters group, you can specify the following 
parameters:
• Calculation Unit Set. You can select the unit set you 
want the calculations done with using the drop-down list. 
There are three standard selections: SI, EuroSI, and 
Field. You can create your own unit set in the Session 
Preferences property view.
Modes Description
Off Select this mode to disable the Selector Block. The function of 
this mode is similar to the Ignored checkbox in the unit 
operations.
Minimum The minimum value from the list of Input Variables is passed 
to the Output stream. 
Maximum The maximum value from the list of Input Variables is passed 
to the Output stream. 
Median The median value of the Input Variables is passed to the 
Output stream. If there are an even number of Input 
Variables, then the higher of the two middle values is passed 
to the Output stream.
Average The average of the Input Variables is passed to the Output 
stream.
Sum The sum of the Input Variables is passed to the Output 
stream.
Product The product of the Input Variables is passed to the Output 
stream.
Quotient The quotient of the Input Variables is passed to the Output 
stream.
Manual This mode is similar to Manual mode in the PID controller. 
This mode allows you to specify the OP directly.
Hand Sel Allows you to select which Input Variable value is written to 
the OP. You can select the PV value using the Selected Input 
field.
 Figure 5.142
Refer to Section 12.3.1 
- Units Page in the 
HYSYS User Guide for 
more information.5-221
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Th• Selected Input. You can select the PV source using the 
drop-down list in this field. This field is only available for 
the Minimum, Maximum, and Hand Sel modes.
Scaling Factors Page
The Scaling Factors page allows you to manipulate the input and 
output parameters.
The Output is a function of the Mode, Gain, and Bias, where the 
Input function is dependent on the mode:
The Input function is multiplied by the Gain. In effect, the gain 
tells how much the output variable changes per unit change in 
the input function. The Bias is added to the product of the Input 
function and Gain. 
Inputs can be individually scaled before the output calculations.
 Figure 5.143
(5.28)
If you want to view the Input function without any Gain or 
Bias adjustment, set the Gain to one and the Bias to zero.
(5.29)
Output f Inputs( ) Gain Bias+×=
Inputscaled Input Gain Bias+×=5-222
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ThThe Inverse Cond. checkbox is used when the selector is writing 
back to its PV, and you are required to scale the input value 
backwards.
5.8.4 Monitor Tab
The Monitor tab displays the results of the Selector Block. It 
consists of two objects: 
• Input PV Data. This group contains the current values 
of the input process variable.
• Output Value. This display field contains the current 
value of the PV for each of the input variables and the 
Output Value is also displayed on the Parameters tab. 
(5.30)
 Figure 5.144
The Output value is not displayed until the Integrator has 
been started.
Input
Inputscaled Bias–
Gain
------------------------------------------=5-223
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ThExample
In the simple example shown here, the median value of Stream 
1, Stream 2, and Stream 3 is passed to the Output, after a Gain 
of 2 and a Bias of 5 have been applied.
These are the steps:
1. Determine f(Inputs), which in this case is the median of the 
Input Variables. The median (middle value) temperature of 
the three streams (10°C, 15°C, 20°C) is 15°C.
2. Determine the Output Value, from the Gain and Bias. The 
Gain is 2, and the Bias is 5°C.
3. The Output is calculated as follows:
5.8.5 Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
5.8.6 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
(5.31)
Output f Inputs( ) Gain Bias+×=
Output 15°C 2.000 5.000°C+×=
Output 35°C=
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-224
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Th5.9 Set
The Set is an operation used to set the value of a specific 
Process Variable (PV) in relation to another PV. The relationship 
is between the same PV in two like objects; for instance, the 
temperature of two streams, or the UA of two exchangers. 
The dependent, or target, variable is defined in terms of the 
independent, or source, variable according to the following 
linear relation:
where:  
Y = dependent (target) variable
X = independent (source) variable
M = multiplier (slope)
B = offset (intercept)
5.9.1 Set Property View
There are two ways that you can add a Set to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Set.
4. Click the Add button.
OR
The Set unit operation can be used in both Dynamic and 
Steady State mode.
(5.32)Y MX B+=5-225
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5-226 Set
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Th1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Set icon. 
The Set property view appears.
5.9.2 Connections Tab
On the Connections tab, you can specify the following 
information:
• Target Object. The stream or operation to which the 
dependent variable belongs. This is chosen by clicking 
the Select Var button. This brings up the Variable 
Navigator property view.
• Target Variable. The type of variable you want to set, 
for example, temperature, pressure, and flow. The 
available choices for Variable are dependent on the 
Object type (stream, heat exchanger, and so forth) Your 
choice of Variable is automatically assigned to both the 
Target and Source object.
• Source Object. The stream or operation to which the 
independent variable belongs.
Notice that when you choose an object for the Target, the 
available objects for the Source are restricted to those of the 
same object type. For example, if you choose a stream as the 
Target, only streams are available for the Source.
 Figure 5.145
Set icon
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
more information.5-226
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ThHYSYS solves for either the Source or Target variable, 
depending on which is known first (bi-directional solution 
capabilities).
5.9.3 Parameters Tab
On the Parameters tab, you can specify values for the slope 
(Multiplier) and the intercept (Offset). The default values for the 
Multiplier and Offset are 1 and 0, respectively.
 Figure 5.146
 Figure 5.1475-227
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5-228 Spreadsheet
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Th5.9.4 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
5.10 Spreadsheet
The Spreadsheet applies the functionality of Spreadsheet 
programs to flowsheet modeling. With essentially complete 
access to all process variables, the Spreadsheet is extremely 
powerful and has many applications in HYSYS.
The Spreadsheet can be used to manipulate or perform custom 
calculations on flowsheet variables. Because it is an operation, 
calculations are performed automatically; Spreadsheet cells are 
updated when flowsheet variables change. In Dynamics mode, 
the Spreadsheet cells are updated when the integrator is 
running.
One application of the Spreadsheet is the calculation of pressure 
drop during dynamic operation of a Heat Exchanger. In the 
HYSYS Heat Exchanger, the pressure drop remains constant on 
both sides regardless of flow. However, using the Spreadsheet, 
the actual pressure drop on one or both sides of the exchanger 
could be calculated as a function of flow.
Complex mathematical formulas can be created, using syntax 
which is similar to conventional Spreadsheets. Arithmetic, 
logarithmic, and trigonometric functions are examples of the 
mathematical functionality available in the Spreadsheet. The 
Spreadsheet also provides logical programming in addition to its 
comprehensive mathematical capabilities. Boolean logic is 
supported, which allows you to compare the value of two or 
more variables using logical operators, and then perform the 
appropriate action depending on that result.
The HYSYS Spreadsheet has standard row/column 
functionality. You can import a variable, or enter a number 
or formula anywhere in the spreadsheet.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-228
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ThYou can import virtually any variable in the simulation into the 
Spreadsheet, and you can export a cell's value to any specifiable 
field in your simulation. There are two methods of importing and 
exporting variables to and from the Spreadsheet:
When you are using the Spreadsheet to return a result back to 
the flowsheet, you must consider its application in terms of the 
overall calculation sequence, particularly when Recycles are 
involved. 
If the Spreadsheet performs a calculation and sends the results 
back upstream, the potential exists for creating inconsistencies 
as the full effect of the previous Recycle loop has not 
propagated through the flowsheet. By using the Calculation 
Sequencing option, you can minimize the potential for problems 
of this nature.
5.10.1 Spreadsheet Property 
View
There are two ways that you can add a Spreadsheet to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
Methods Description
Using the 
Variable 
Navigator 
Do one of the following:
• On the Connections tab, click the Add Import or Add 
Export button. 
• On the Spreadsheet tab, right-click the cell you want 
and select export/import command from the object 
inspection menu.
Then using the Variable Navigator, select the variable you 
want to import or export.
Dragging 
Variables 
Simply right-click the variable value you want to import, 
and drag it to the desired location in the Spreadsheet. If 
you are exporting the variable, drag it from the 
Spreadsheet to an appropriate location.
When using the Dragging Variables method, the property 
views have to be non-modal.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
more information.
Refer to Section 7.2 - 
Main Properties in the 
HYSYS User Guide for 
more information on the 
Calculation Sequencing 
option.5-229
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5-230 Spreadsheet
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Th2. Click the Logicals radio button.
3. From the list of available unit operations, select 
Spreadsheet.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Spreadsheet icon. 
The Spreadsheet property view appears.
5.10.2 Spreadsheet Functions
The HYSYS Spreadsheet has extensive mathematical and logical 
function capability. To view the available Spreadsheet Functions 
and Expressions, click the Function Help button to open the 
Available Expressions and Functions property view. 
 Figure 5.148
All functions must be preceded by “+” (straight math) or “@” 
(special functions like logarithmic, trigonometric, logical, 
and so forth).
Examples are "+A4/B5" and "@ABS(A4-B5)".
Spreadsheet icon
Click the Function 
Help button to 
access the list of 
available 
spreadsheet 
functions in HYSYS.
Click the 
Spreadsheet Only 
button to open the 
a property view 
containing only the 
spreadsheet and its 
content.5-230
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ThThe Available Expressions and Functions property view contains 
the following tabs:
• Mathematical Expressions
• Logical Expressions
• Mathematical Functions
General Math Functions
The following arithmetic functions are supported:
Several other mathematical functions are also available: 
General 
Operations
Method of Application View
Addition Use the “+” symbol.
Subtraction Use the "-" symbol.
Multiplication Use the “*” symbol.
Division Use the “/” symbol, typically 
located on the numeric keypad, 
or next to the right SHIFT key. 
(Do not use the “\” symbol).
Absolute Value  “@Abs”. 
Advanced 
Operations
Method of Application View
Power Use the “^” symbol. 
Example:  +3^3 = 27
Example 2: +27^(1/3)=3
Notice that the parentheses are 
required in this case, since the cube 
root of 27 (or 27 to the power of 
one-third) is desired. 
Square Root "@SQRT". 
Example: @sqrt(16) = 4 
Notice that capitalization is 
irrelevant. You can also use “@RT” to 
calculate a square root. (Example: 
@rt(16)=4)
Refer to the 
Calculation Hierarchy 
section for more 
information.5-231
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ThCalculation Hierarchy
The usual hierarchy of calculation is used (Brackets, Exponents, 
Division and Multiplication, Addition and Subtraction). For 
example:
+6+4/2 = 8 (not 5)
since division is performed before addition. However,
+(6+4)/2 = 5
because any expressions in parentheses are calculated first.
Logarithmic Functions
Pi Simply enter "+pi" to represent the 
number 3.1415...
Factorial Use the “!” symbol. Example: +5!-
120=0
Log Function Method of Application View
Natural Log “@ln”. 
Example:  @ln(2.73)=1.004
Base 10 Log "@log". 
Example: @log(1000)=3
Exponential “@exp”. 
Example: @exp(3)=20.09
Hyperbolic  “@sinh”, “@cosh”, “@tanh”. 
Example: @tanh(2) = 0.964
Expression 
within Range
“@Inrange”
Returns a 1 if the number is 
within the range specified within 
the function.
Example: A1 = 5
• @Inrange(A1,4,7) = 1
• @Inrange(A1,6,10) = 0
Advanced 
Operations
Method of Application View5-232
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ThTrigonometric Functions
All of the trigonometric functions are supported, including 
inverse and hyperbolic functions: 
Trigonometric functions can be calculated using radian, degree 
or grad units, by selecting the appropriate type from the Angles 
in drop-down list in the Current Cell group.
Expression 
within Limit
“@Inlimit”
Returns a 1 if the number is 
within the range, on either side 
of the number, specified within 
the function.
Example: A1 = 5
• @Inlimit(A1,7,2) = 1
• @Inlimit(A1,7,1) = 0
Expression 
within 
Percentage
“@Inpercentage”
Returns a 1 if the number is 
within the percentage, on either 
side of the number, specified 
within the function. 
Example: A1 = 5
• @Inpercentage(A1,8,40) = 
1
• @Inpercentage(A1,8,35) = 
0
Trig Function Method of Application View
Standard “@sin”, “@cos”, “@tan”. 
Example:  @cos(pi) =-1 (Radian 
Angles) 
Inverse “@asin”, “@acos”, “@atan”. In this 
case, the number to which the 
function is being applied must be 
between -1 and 1.
Example: @asin(1) = 1.571 (Radian 
Angles)
Parentheses are required for all logarithmic and 
trigonometric functions. The capitalization is irrelevant; 
HYSYS calculates the function regardless of how it is 
capitalized.
Log Function Method of Application View5-233
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ThLogical Operators
The Spreadsheet supports Boolean logic. For example, suppose 
cell A1 had a value of 5 and cell A2 had a value of 10. Then, in 
cell A3, you entered the formula (+A1”
Less Than  “<“
Greater Than or Equal to  “>=”
Less Than or Equal to  “<=”
You always need to provide an ELSE clause (IF/THEN 
statements are not accepted). 
Parentheses are mandatory for IF/THEN/ELSE statements.5-234
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ThFor example, suppose cell B2 contained the number 6. The 
statement
“@if (B2>10) then (10) else (B2/2)”
would result in the value 3 being displayed in the cell.
5.10.3 Spreadsheet Interface
Importing and Exporting Variables 
by dragging
You can drag the contents of any cell in the simulation into the 
Spreadsheet. Simply position the pointer on that field, right-
click and drag the value to any cell in the Spreadsheet. 
 Figure 5.149
View Type Description
Non-Modal A non-Modal property view has a Minimizing button and 
Maximizing button in the upper-right had corner, and has a 
double border. You can drag variables outside a non-Modal 
property view.
Modal A Modal property view has a ‘pin’ in the upper-right corner, 
and has a single border. You cannot drag variables outside 
a Modal property view.
Select the pin to convert a Modal property view to a Non-
Modal property view.5-235
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ThWhen you drag to a cell in the Spreadsheet, you see the “bulls-
eye” cursor. Release the secondary mouse button, and the value 
is dropped in that cell. In the Imported From field in the Current 
Cell group (which appears when the cursor is on an imported 
cell), you see the Object for that particular cell. The Object 
Variable appears in the Variable field. 
Every time you make a change to (or HYSYS re-calculates) a 
variable you have placed in the Spreadsheet, your data is 
updated appropriately.
You can remove an attachment at any time by positioning the 
pointer in the appropriate cell, right-clicking and selecting 
Disconnect Import/Export command from the Object Inspect 
menu.
The window from which you are dragging must be unpinned 
(non-modal). The Spreadsheet window is non-modal by 
default.
 Figure 5.150
Right-click and drag a variable (in this case, 
Feed Molar Flow) to a cell in the Spreadsheet. 
You see the bulls-eye cursor, indicating that 
you can transfer the variable to that location. 
Release the mouse button and the variable is 
transferred. In the Imported From cell, you 
can view the variable source.
Object Inspect menu5-236
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ThEnumeration in Spreadsheet
Similar to the drag-and-drop importing method, the Ignore 
checkbox of each operation can be imported onto the 
Spreadsheet page of the Spreadsheet operation. 
For any unit and logical operations, you can right-click on the 
Ignore checkbox, and drag-and-drop the bulls-eye onto a 
spreadsheet cell. For an active operation, the cell should then 
read 0 - Not Ignored. For a disable operation (in other words, 
the Ignore checkbox is selected in the operation property 
view), the cell should read 1-Ignored.
The ignore status changes automatically when you select or 
clear the Ignore checkbox of the corresponding operation.
This feature is especially useful when you are working with 
controllers or actuator fail positions. The ignore status can be 
used as a number in a formula or in a Boolean expression even 
though the cell displays the text that reflects the status.
 Figure 5.1515-237
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ThImporting Variables by Browsing
You can also import a variable by positioning the cursor in an 
empty cell of the Spreadsheet and right-clicking. The Object 
Inspect menu appears, select the Import Variable command.
Using the Variable Navigator select the flowsheet variable you 
want to import to the Spreadsheet. This method of importing 
variables is similar to the way variables are imported on the 
Connections tab.
Exporting Formula Results
Variables are exported using the Variable Navigator, or by 
“dragging” the variable. You can only export Formula Results, in 
other words, values that appear in red. 
There are three ways to export:
• Right-click and drag to the location where you want to 
export the formula result. You see a bulls-eye cursor 
indicating that you can export to the current location.
 Figure 5.152
You can only drag the variables to and fro between non-
modal property views.
If you export into a field containing a calculated value, you 
usually get a consistency error, except in the unlikely case 
that the calculated and exported values are exactly the 
same. 
The export value replaces a specifiable value.
The Object Inspect 
menu is accessed by 
right-clicking the cell in 
the spread sheet.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
more information.5-238
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Th• Right-click and select Export Formula Result command 
from the object inspect menu. Using the Variable 
Navigator, choose where you want to export the Formula 
Result.
• Define an exported variable on the Connections tab by 
clicking the Add Export button and selecting the export 
object and variable using the Variable Navigator.
Similarly, the same Spreadsheet cell cannot act as the Source 
for more than one field. To work around this, type the cell name 
with the variable you want to export into a new location in the 
Spreadsheet, and export the new variable.
Notice that when you export a variable from a Spreadsheet cell, 
that variable is given the same units as the units of the location 
to which you exported it.
For example, suppose you wanted to assign the pressure of 
stream Feed to another stream. In cell B1, enter the formula 
+A1, and then export the contents of the cell to the pressure 
cell of the appropriate stream, using one of the methods 
outlined above. 
 Figure 5.153
You cannot use the same Spreadsheet cell as both the Target 
and Source field in calculations. 
 Figure 5.154
The object inspect menu 
is accessed by right-
clicking the cell in the 
spread sheet.
Because the 
contents of cell A1 
cannot be both an 
import and export, 
the formula +A1 is 
entered in cell B1. 
cell B1 is then 
exported to the 
Waste pressure.5-239
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5-240 Spreadsheet
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ThView Associated Object
You can view an object associated with a specific cell by right-
clicking and selecting the View Associated Object. 
For instance, if you dragged the temperature of a stream from 
the Worksheet into the Spreadsheet, the associated object 
would be that stream. When you select View Associated Object, 
you are taken to the property view for that stream. 
If there is no object associated with the current cell, this menu 
selection is disabled.
5.10.4 Spreadsheet Tabs
Connections Tab 
On the Connections tab, you can add, edit, and delete Imports 
and Exports. As mentioned earlier, you can also import and 
export variables by dragging to and from the Spreadsheet.
To add an import, click the Add Import button, and choose the 
variable using the Variable Navigator. In the Cell column, type 
or select from the drop-down list the Spreadsheet cell to be 
connected to that variable. When you move to the 
For this simple example, you could use the Set operation. For 
more complex situations, you must use the Spreadsheet.
 Figure 5.155
You can also view the associated object of an imported cell, 
by double-clicking on that cell.
The Object Inspect menu 
is accessed by right-
clicking the cell in the 
spread sheet.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
more information.5-240
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ThSpreadsheet tab, that variable appears in the cell you 
specified. An example is illustrated in the following figure.
You can edit or delete an import by positioning the cursor in the 
appropriate row, and clicking the Edit Import or Delete 
Import buttons. Adding, editing, and deleting Exports is 
performed in a similar manner. You can also edit the 
Spreadsheet Name on this tab.
Parameters Tab
On the Parameters tab of the Spreadsheet property view, you 
can set the dimensions of the Spreadsheet and choose a Unit 
Set.  
 Figure 5.156
Parameters Description
Number of 
Columns and 
Rows 
You can set the dimensions of the Spreadsheet. Notice that 
if you set the dimensions of the Spreadsheet smaller than 
what is already specified, you permanently delete the 
contents of cells which are removed. For instance, the 
contents of cell A4 and B4 are deleted when you set the 
Number of Rows to 3.
Units You can choose a Unit Set for the Spreadsheet. All values in 
the Spreadsheet appear using units from the set you have 
chosen.
Refer to Section 12.3.1 
- Units Page in the 
HYSYS User Guide for 
more information about 
Unit Set.5-241
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ThExportable Cells
Prior to explaining how the Exportable cells are created, the 
difference between exporting from the Spreadsheet (assigning a 
value from the Spreadsheet to a Process Variable) or importing 
from the Spreadsheet (accessing a Spreadsheet variable from 
another object) must be explained.
Results that are exported from the Spreadsheet to a specifiable 
process variable can only be connected once. In other words, 
the same cell cannot be connected to two process variables.
However, locations in the program which can import from the 
Spreadsheet (for example, PID Controller Cascade Source, 
Adjust Target Variable or Databook Variable) can access any 
cell, including those which are being exported to a flowsheet 
process variable. The Exportable Cells list has been created to 
allow objects which use the Variable Navigator to access 
variables associated with the Spreadsheet.
The Exportable Cells group displays all cells which can be 
exported (including those which have been exported). The 
Visible Name, Variable Name, and Variable Type either displays 
the information you have specified for the associated cell on the 
Spreadsheet itself, or contains the information appropriate to 
 Figure 5.1575-242
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Ththe process variable that the cell has been exported to. In the 
former case, this information is modifiable; you can change it 
here or on the Spreadsheet itself. In the latter, you cannot 
modify the information as it is set by the process variable the 
cell has been exported to. 
For instance, if you export a Spreadsheet value to the Separator 
Valve Opening cell, the Variable Name and Variable Type are 
Valve Opening and Percent, respectively.
You can edit the Variable Name and Variable Type for all non-
exported variables that appear in the list 
The Visible Name and Variable Name columns display 
variables which can be exported. The fact that a variable 
appears in this list does not necessarily mean that the 
variable has been exported.
When you access the Spreadsheet as the Object (for 
example, through the Variable Navigator), the contents of 
the Visible Name cell appear in the Variable List.
 Figure 5.158
There are three variables in 
the Variable List for 
SPRDSHT-1 corresponding 
to cells A1, B3, and B6. 
Notice that the Variable 
Names were added 
manually.
When you use 
the Variable 
Navigator and 
select 
SPRDSHT-1 as 
the Object you 
see cells A1, 
B3, B6, A4, 
C5, and D4 in 
the Variable 
List.5-243
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ThFormulas Tab
The Formulas tab displays a summary of all the formulas 
included in your spreadsheet. The table lists the name of the cell 
the formula is located in, the formula and the result of the 
formula.
Spreadsheet Tab
The Spreadsheet tab, with the labelled rows and columns, is 
similar to conventional Spreadsheets.
From this tab, you can import and export variables, disconnect 
imports/exports, view associated object property views, define 
formula expressions, and modify variable names.
Spreadsheet variables attached to the Controller, Adjusts, 
and Databook are not exported, but are imported from that 
Object.
 Figure 5.1595-244
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ThCurrent Cell Group
The Current Cell group displays information specific to the 
contents of the highlighted cell. For all cases, the Current Cell 
location appears.
Cell containing a Formula or non-imported specifiable 
value
The Variable Type and Variable Name are shown. You can 
choose a new Variable Type from the drop-down list, and you 
can edit the Variable name. 
Cells containing a formula or a non-imported specifiable value 
are automatically added to the Variable list on the Parameters 
tab; the Exportable checkbox is selected.
Spreadsheet Function For More Information
Importing and Exporting See sections:
• Importing and Exporting Variables 
by dragging 
• Importing Variables by Browsing
Associated Object Views Refer to section View Associated Object.
Formula Expressions Refer to Section 5.10.2 - Spreadsheet 
Functions.
Variable Names Refer to section Exportable Cells.
 Figure 5.160
The Variable Type sets the units for the Spreadsheet cell. For 
example, the SI units for Variable Type Area are m2.5-245
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ThCell containing an Export
The object and variable to which the contents of the cell were 
exported are shown. The Exportable checkbox is selected in 
this case. You cannot change the Variable Name, since it is a 
HYSYS default.
Cell containing an Import  
The object and variable from which the contents of the current 
cell were imported are shown. You cannot change the Variable 
name, since it is a HYSYS default.
Calculation Order Tab
The Calculation Order tab allows you to set the calculation level 
of each of the cells in the spreadsheet. Click the Calculation 
Order Help button to view the rules for setting the calculation 
levels.
 Figure 5.161
 Figure 5.162
 Figure 5.1635-246
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ThUser Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
Function Help and Spreadsheet Only 
buttons
Clicking the Function Help button allows you to view the 
available Spreadsheet Functions and Expressions. Notice that 
this Help Window has three tabs:
• Mathematical Expressions
• Logical Expressions
• Mathematical Functions
Click the Spreadsheet Only button to view just the Spreadsheet 
cells in a separate window. This feature is useful when you have 
completely set up the Spreadsheet, and you only want to view 
the cell results.
5.11 Stream Cutter
The stream cutter is an object that allows you to switch the fluid 
package of a stream anywhere in the flowsheet. This concept of 
changing fluid package is called fluid package transition.
HYSYS automatically adds a stream cutter operation in 
between two objects on the PFD property view, where a 
switch in fluid package occurs.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
Refer to Section 5.10.2 
- Spreadsheet 
Functions for more 
information.5-247
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5-248 Stream Cutter
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Th5.11.1 Stream Cutter Property 
View
To add a Stream Cutter to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Stream 
Cutter.
4. Click the Add button.
The Stream Cutter property view appears.  
The Stream Cutter property view contains the following tabs:
• Design
• Transitions
• Worksheet 
 Figure 5.1645-248
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ThChanging Fluid Package
Currently, there are several methods for you to change the fluid 
package of objects:
• using a drop-down list from the unit operation property 
view.
• right-clicking on a selected group of operations in the 
PFD property view.
• changing the flowsheet fluid package in the basis 
environment.
If you add an operation and change its fluid package before any 
streams are connected to the operation, then connect empty 
streams (default fluid package, not connected to anything and 
empty composition) to the operation, HYSYS changes the empty 
stream’s fluid package to the operation’s fluid package. 
If a stream connected to an operation with a specified fluid 
package has one of the following:
• a specified fluid package.
• a connection to another operation.
• its composition specified.
HYSYS adds a stream cutter between the stream and the 
operation the stream is attached to.
HYSYS does not allow fluid package transitions in 
electrolytic flow sheets or inside of column flow sheets. Fluid 
package transitions are allowed only in standard flow 
sheets.
It is recommended to have all the fluid package 
specifications in place before switching to dynamics.5-249
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5-250 Stream Cutter
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ThChanging the Fluid Package in the Unit 
Operation Property View
You can change the fluid package of an operation using the Fluid 
Package drop-down list on the Connections page of the Design 
tab for the Operation property view.
In this method, HYSYS propagates the new fluid package 
specifications to connected operations and streams. This 
propagation stops when it encounters one of the following:
• a fluid package (either on an operation or stream) that 
you have already specified.
• an operation with more than one feed or product.
• a template or column.
• an existing stream cutter.
For example, consider a separator with its liquid stream 
connected to a pump, which is in turn connected to a valve. All 
objects are using FP1, the default for the flowsheet.
If you specify the fluid package of the valve to FP2, HYSYS first 
propagates downstream. HYSYS finds a single stream, 5, with a 
fluid package at default status, which is FP1. So HYSYS 
calculates and changes stream 5 to the FP2 fluid package 
setting.
You can change the fluid package of a stream on the Stream 
property view - Worksheet tab - Conditions page.
 Figure 5.1655-250
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ThNext HYSYS propagates upstreams. The stream 4 also has a 
default fluid package setting. So HYSYS calculates, changing 
stream 4 to FP2 setting. The propagation goes along stream 4 
until it encounters the pump. The pump has a default fluid 
package setting, and only a single inlet and a single outlet 
(energy streams are not considered because they have no 
dependence on fluid package). HYSYS calculates and changes 
the pump fluid package setting to FP2. The propagation 
continues to the pump’s inlet stream 3. The stream has a 
default fluid package setting of FP1, so HYSYS calculates and 
moves upstream to the separator. The separator has multiple 
outlet streams. So when HYSYS encounters the separator the 
propagation function stops, and HYSYS adds a cutter.
Since the propagate calculation has already calculated stream 3 
with fluid package FP2, HYSYS generates another stream called 
3- with FP1 as the fluid package, and renames stream 3 to 3+, 
which has FP2 as the fluid package.
At the point where the propagation stopped, a stream cutter is 
automatically added to the flowsheet between the operations in 
question, and a fluid package transition is added to the cutter’s 
transition collection. This fluid package transition automatically 
chooses its component mappers to be the default mapper of the 
The propagation calculation basically steps along. The valve 
calculates into stream 4, stream 4 calculates into the pump, 
the pump calculates into stream 3, and so forth.
 Figure 5.1665-251
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Thappropriate map collection. The default mapper can be changed 
by entering the Basis environment, opening the Simulation 
Basis Manager property view, and selecting the Component 
Maps tab. 
The fluid package transition function, however, does not 
automatically choose a transfer basis. You must make this 
decision. The status window should have a missing required info 
error for the stream cutter stating Transitions not ready. 
By double-clicking the statement in the status window, the 
stream cutter property view opens already on the Fluid Pkg page 
of the Transitions tab. 
In addition to automatically adding stream cutters where 
transitions between fluid packages are occurring, HYSYS can 
determine when stream cutters are no longer needed and 
prompts you to decide if they should be removed. 
For instance, continuing on from the previous example, change 
the pump’s fluid package back to FP1. 
 Figure 5.167
 Figure 5.168
Refer to the Fluid Pkg 
Page section for more 
information.5-252
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ThFirst consider the downstream propagation. This propagation 
goes through the pump outlet stream 4 and finds the valve. 
Since this is where you made your first fluid package 
specification, the status of the fluid package is specified and 
propagation stops, and a stream cutter is automatically added 
(again the fluid package transition requires a transfer basis).
Now consider the upstream propagation. The FP1 setting 
propagates through the inlet of the pump and encounters the 
stream cutter along stream 3+. The propagation stops 
according to the rules. This stream cutter contains the fluid 
package transition between FP1 and FP2, but now both sides are 
FP1. Since you have not added any other transitions to the 
stream cutter, the stream cutter only contains a fluid package 
transition. This fact combined with the fact that each side of the 
cutter has the same fluid package, HYSYS can assume the 
stream cutter is no longer needed. 
A property view appears at this point listing all unnecessary 
stream cutters, and you can select which ones, if any, to delete.
 Figure 5.169
 Figure 5.170
Select or clear the 
checkbox in the 
Delete column to 
remove or keep the 
stream cutters.
Click the Continue 
button to remove the 
selected stream 
cutters.5-253
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5-254 Stream Cutter
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ThChanging the Fluid Package Using the Object 
Inspect Menu
In order to bypass the propagation rules used by the unit 
operation property view method, you can change the fluid 
package of only certain operations of your choice. Select the 
operations you want from the PFD (like you would for copy/
paste), then right-click to open the object inspect menu. Select 
the Change Fluid Package command from the menu, and the 
Change Fluid Pkg property view appears. 
Using the drop-down list, you can select the fluid package you 
want for the selected objects.
Consider the separator-pump-valve train defined in the previous 
section. By the end, you were left with the separator and pump 
using FP1 and the valve using FP2, with a cutter between the 
pump and valve.
At this state, the flowsheet contains two individual fluid package 
specifications, one on the valve and the other on the pump. 
Depending on the flowsheet configuration and the type of 
 Figure 5.171
 Figure 5.172
You can select the transfer 
basis using the radio 
buttons in the Transfer 
Basis for Cutters group.5-254
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Thoperations involved, it is important to note that by using the 
unit operation property view method you could end up with a 
less-than-desirable flowsheet with stream cutters where you 
didn’t want them. These hassles can be avoided by using object 
inspect, and the same result achieved in the previous section 
with two specifications can be achieved with one.
To achieve the results in the above figure using only one 
specification, you use the object inspect menu. First select the 
valve and attached streams on the PFD. Then right-click to bring 
up the object inspect menu, and select the Change Fluid Pkg 
command. The Change Fluid Pkg property view appears. Select 
FP2 from the drop-down list, and a transfer basis from the radio 
button. Propagation is suppressed, so only streams 4 and 5 and 
the valve is switched to FP2 fluid package. A stream cutter is 
also added with default maps and the selected transfer basis 
between valve inlet stream 4 and the pump outlet stream 4.
If you use the object inspect method to change fluid packages, 
and you happen to have a heat exchanger or LNG selected, all 
exchange sides of the exchanger in question get switched. There 
is no way of picking and choosing particular exchanger sides, 
except from the actual exchanger and LNG property views.
Changing the Fluid Package from the Basis 
Environment
You can change the fluid package of the default fluid package 
setting in the Basis environment. Open to the Simulation Basis 
Management property view, and click on the Fluid Pkgs tab. 
Select a different fluid package using the Default Fluid Pkg drop-
down list. Notice that when you change the default fluid package 
setting, only objects whose fluid packages are still at default 
setting get switched to the new fluid package default.
Refer to Section 2.2 - 
Fluid Packages Tab in 
the HYSYS Simulation 
Basis guide for more 
information.5-255
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5-256 Stream Cutter
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Th5.11.2 Design Tab
The Design tab contains the following pages:
• Connections
• User Variables
• Notes
Connections Page
You can select the inlet and outlet streams of the stream cutter 
on this page. You can change the name of the stream cutter in 
the Name field.
You can click on the Remove Cutter button to uncut the 
attached streams. The Remove Cutter button is available only 
after a stream has been specified in both the inlet field and 
outlet field.
 Figure 5.173
The difference between the Remove Cutter button and 
Delete button is that the Remove Cutter button maintains 
upstream and downstream connections.5-256
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor, where you can record 
any comments or information regarding the operation or to your 
simulation case in general.
5.11.3 Transitions Tab
The Transitions tab contains the following pages:
• Transitions
• Fluid Pkg
The Fluid Pkg page is available only after you add the option into 
the Transitions page, as shown in the figure below.
The Fluid Pkg page is automatically available, if the stream 
cutter was generated by HYSYS to perform fluid package 
transition.
 Figure 5.174
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.5-257
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ThTransitions Page
The Transitions page contains a table and three buttons: Add, 
View, and Remove. When no transition type has been selected, 
only the Add button is available for use, and the table is blank as 
shown in the figure below.
Adding a Transition
Click the Add button to open the Select Transition property 
view. 
From this property view you can add the transition type you 
want the stream cutter to perform. Currently there is only one 
transition type available: fluid package.
 Figure 5.175
 Figure 5.176
Select the transition type 
you want from the list, 
and click the Add button.
Click the Close button to 
close the property view 
when you are done.5-258
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ThOnce you have selected a transition type and return to the 
transition page, the View and Remove buttons are available for 
use.
Viewing a Transition
Select a transition type from the list, and click the View button 
to open a property view that contains more detailed information 
about the transition type and its functions. The figure below 
shows a fluid package transition property view.
The Fluid Package Transition property view consists of the 
following objects: 
 Figure 5.177
Depending on how the stream cutter is added and how the 
transition type is defined, the field texts can be black to 
indicate non-changeable values, or blue to indicate 
changeable values.
Object Description
Inlet Stream 
Field
Displays the name of the stream going into the stream 
cutter.
Inlet Fluid Pkg 
Field
Displays the fluid package being used by the inlet 
stream.
Outlet Stream 
Field
Displays the name of the stream coming out of the 
stream cutter.5-259
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5-260 Stream Cutter
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ThOutlet Fluid Pkg 
Field
Displays the fluid package being used by the outlet 
stream.
Forward 
Component Map 
Group
Lists the component maps that are used if composition 
is passed from the inlet stream to the outlet stream.
• Click the Add button to add another component 
map.
• Click the View button to open the Component 
Map property view, that contains more 
information regarding the selected component 
map. 
• Click the Delete button to delete the selected 
component map. You cannot delete the default 
component map.
The list does not affect the simulation, only the 
selected map does. The map determines how 
components are mapped across. 
The maps are necessary only when dealing with 
component lists that are different. The maps tell 
HYSYS how to transfer the compositions.
Backward 
Component Map 
Group
Lists the component maps that are used if composition 
is passed from the outlet stream to the inlet stream.
• Click the Add button to add another component 
map.
• Click the View button to open the Component 
Map property view, that contains more 
information regarding the selected component 
map. 
• Click the Delete button to delete the selected 
component map. You cannot delete the default 
component map.
A component map is necessary when, you have a fluid 
package FP7 with seven components and another fluid 
package FP6 with six components. HYSYS cannot just 
pass the mole fractions of the seven components to 
the other fluid package, because there are only six 
slots to put the information in. The component map 
tells HYSYS how to transfer the mole fraction values.
Transfer Basis 
Group
Contains six transfer basis types available for the fluid 
package transition tool. You must select one of the 
transfer basis radio button.The transfer basis types 
are:
• T-P Flash. Transfers temperature or pressure.
• P-H Flash. Transfers pressure and enthalpy
• VF-T Flash. Transfers vapour fraction and 
temperature.
• VF-P Flash. Transfers vapour fraction and 
pressure.
• None Required. Select this radio button when 
there is no need for a transfer basis. Use this 
transfer only for energy streams.
• None Set. This is the default setting. Stream 
cutter does not solve if the radio button is 
selected.
Object Description
Refer to Section 6.3 - 
Component Map 
Property View in the 
HYSYS Simulation 
Basis guide for more 
information about the 
Component Map 
property view.
Refer to Section 6.3 - 
Component Map 
Property View in the 
HYSYS Simulation 
Basis guide for more 
information about the 
Component Map 
property view.5-260
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ThRemoving a Transition
Select the transition type you want to remove from the table, 
and click the Remove button. If the transition type is currently 
being used in the stream cutter, the Remove button 
automatically becomes unavailable when you select the 
transition from the table.
When you remove a transition from the table, the page 
associated with the transition is also removed from the 
Transition tab.
Activate a Transition
Select the checkbox in the Active column to activate the 
associated transition type. Clearing the checkbox associated 
with the transition type, deactivates the transition but does not 
remove the transition from the table.
Active Checkbox This checkbox is the same checkbox from the table on 
the Transitions page. You can select or clear this 
checkbox to activate or deactivate the transition. When 
the Active checkbox changes in this property view, the 
changes also occur in the table on the Transitions 
page.
Imbalance 
Button
Click this button to open the Imbalance Info property 
view.
The Imbalance Info property view displays any mole, 
mass, or liquid volume imbalance that can occur when 
switching fluid package.
The property view is pertinent for fluid package 
transition involving two different components list.
 Figure 5.178
Object Description
Imbalance Info property 
view
The selected transition is Fluid Pkg, 
which is also the transition being used 
in the stream cutter. So the Remove 
button is disabled.5-261
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5-262 Stream Cutter
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ThFluid Pkg Page
The Fluid Pkg page contains information about the fluid package 
transition. You can also change the transfer basis on this page. 
The following table lists and describes the objects on this page.
 Figure 5.179
Depending on how the stream cutter is added and how the 
transition type is defined, the field texts can be black to 
indicate non-changeable values, or blue to indicate 
changeable values. 
Object Description
Inlet Fluid Pkg 
Field
Displays the fluid package being used by the inlet 
stream.
Outlet Fluid Pkg 
Field
Displays the fluid package being used by the outlet 
stream.5-262
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ThForward Maps 
Group
Lists the component maps that are used if composition 
is passed from the inlet stream to the outlet stream.
• Click the Add button to add another component 
map.
• Click the View button to open the Component 
Map property view, that contains more 
information regarding the selected component 
map. 
• Click the Delete button to delete the selected 
component map. You cannot delete the default 
component map.
The list does not affect the simulation, only the 
selected map does. The map determines how 
components are mapped across. 
The maps are necessary only when dealing with 
component lists that are different. The maps tell 
HYSYS how to transfer the compositions.
Backward Maps 
Group
Lists the component maps that are used if composition 
is passed from the outlet stream to the inlet stream.
• Click the Add button to add another component 
map.
• Click the View button to open the Component 
Map property view, that contains more 
information regarding the selected component 
map. 
• Click the Delete button to delete the selected 
component map. You cannot delete the default 
component map.
A component map is necessary when, you have a fluid 
package FP7 with seven components and another fluid 
package FP6 with six components. HYSYS cannot just 
pass the mole fractions of the seven components to 
the other fluid package, because there are only six 
slots to put the information in. The component map 
tells HYSYS how to transfer the mole fraction values.
Transfer Basis 
Group
Contains six transfer basis types available for the fluid 
package transition tool. You must select one of the 
transfer basis radio button.The transfer basis types 
are:
• T-P Flash. Transfers temperature or pressure.
• P-H Flash. Transfers pressure and enthalpy
• VF-T Flash. Transfers vapour fraction and 
temperature.
• VF-P Flash. Transfers vapour fraction and 
pressure.
• None Required. Select this radio button when 
there is no need for a transfer basis. Use this 
transfer only for energy streams.
• None Set. This is the default setting. Stream 
cutter does not solve if the radio button is 
selected.
Object Description
Refer to Section 6.3 - 
Component Map 
Property View in the 
HYSYS Simulation 
Basis guide for more 
information about the 
Component Map 
property view.
Refer to Section 6.3 - 
Component Map 
Property View in the 
HYSYS Simulation 
Basis guide for more 
information about the 
Component Map 
property view.5-263
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5-264 Transfer Function
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Th5.11.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. The PF Specs page is relevant to 
Dynamics cases only.
5.12 Transfer Function
The Transfer Function block is a logical operation which takes a 
specified input, and applies the chosen transfer function to 
produce an output. A typical use of the Transfer Function is to 
apply disturbances to a process, such as varying the 
temperature of a feed stream without having to add a 
disturbance manually. It is also useful to simulate a unit for 
which you know the response characteristics (gain, damping 
factor, period) but not the actual equations involved.
The following Transfer Functions are available:
• First & second order lead
• First & second order lag
• Second order lag / sine wave
• Delay
• Integrator
• Ramp
• Rate Limiter
The second order lag can be defined either as a series of two 
first-order lags, or as a single explicit second order lag.
Active Checkbox This checkbox is the same checkbox from the table on 
the Transitions page. You can select or clear this 
checkbox to activate or deactivate the transition. When 
the Active checkbox changes in this property view, the 
changes also occur in the table on the Transitions 
page.
View Button Click this button to open the transition type property 
view. 
Object Description
Refer to the section on 
Viewing a Transition 
for more information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.5-264
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ThCombinations of the above functions may be used to produce 
the desired output. The combined transfer function is as follows:
The input X(s) is multiplied by the transfer function to obtain the 
output. Notice that the input (or Process Variable Source) is 
optional; you can use a fixed value as the input.
The transfer function is defined here in the Laplace Domain 
(using the Laplace Variables). When in the Laplace Domain, the 
overall transfer function is simply the product of the individual 
transfer functions.
The Laplace Transfer Function must be converted to a real-time 
function in order to be meaningful for a dynamic simulation. For 
instance, the Laplace Transform for the sine function is:
When converted to the time domain by taking the inverse 
Laplace, we obtain:
(5.33)
(5.34)
(5.35)
(5.36)
G s( ) Lead1 s( )Lead2 s( )Lag1 s( )Lag2 s( )W s( )D s( )R s( )=
Y s( ) G s( )X s( )=
G ω
s2 ω2+
-----------------=
f t( ) ωtsin=5-265
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5-266 Transfer Function
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Th5.12.1 Transfer Function 
Property View
There are two ways that you can add a Transfer Function to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Logicals radio button.
3. From the list of available unit operations, select Transfer 
Function Block.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Transfer Function icon.
The Transfer Function property view appears.
 Figure 5.180
Transfer Function icon
Click the Face Plate 
button to access the 
Transfer Function face 
plate property view.
Select the G(s)Enabled 
checkbox to combine 
more than one specified 
functions in the 
Parameters tab.5-266
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Th5.12.2 Connections Tab
The following information is shown on the Connections tab:
You can click the Equation Help button to view the Transfer 
Function equations.
5.12.3 Parameters Tab
The Parameters tab allows you to define the entire transfer 
function G(s), by defining the integrator, delay, lag, lead, and 
2nd order transfer functions. 
The Parameters tab contains the following pages:
• Configuration
• Integrator
• Delay
• Lag
• Lead
• 2nd Order
• Ramp
• Rate Limiter
The last seven pages allow you to define the different transfer 
function terms. Each of these pages contains the Active Transfer 
Function group, which consists of a number of checkboxes 
corresponding to the available components of the Transfer 
Function. By selecting the appropriate checkbox, you can 
include that term in the overall Transfer Function. When you 
activate individual functions on the Integrator/Delay/Lag/Lead/
Input Required Description
Name The name of the Transfer Function Block.
Process Variable 
Source
A stream or operation. You can select the PV Object 
and Variable by clicking the Select PV button. 
The Process Variable is optional. If you do not specify a 
PV, enter a constant PV on the Parameters tab.
Transformed PV 
Target Object
A stream or operation. Select the PV Object and 
Variable by clicking the Select PV’ button. The PV 
Target is not required to have the same variable type 
as the PV Source.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
more information.5-267
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5-268 Transfer Function
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Th2nd Order/Ramp/Rate Limiter pages, the appropriate 
checkboxes are then selected in this group.
Configuration Page
The Configuration page allows you to define the Process and 
Output Variable limits. 
 Figure 5.181
 Figure 5.1825-268
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ThThe Operational Parameters group contains the following 
parameters:
Selecting the Reset out of range PV value using the 
specified range checkbox tells HYSYS to reset the PV input 
value whenever the PV value deviates outside the specified 
range. The specified range can be entered in the Ranges group. 
The reset value is the value entered in the PV field from the 
Operational Parameters group.
The Ranges group contains the following parameters:
Parameter Description
PV The value of the PV input (Process Variable or constant 
PV) is shown in this field.
• If you did not define a PV source in the 
Connections tab, then you must specify a 
constant PV value in this field. Notice the text is 
blue in colour, indicating you can change this 
value.
• If you defined a PV source on the Connections 
tab, then this field displays the PV Input. Notice 
the text is black in colour, indicating it is a HYSYS 
calculated value.
OP Displays the calculated value of the PV Output.
Output Variable 
Type
Displays the OP variable type.
The Reset out of range PV value using the specified range 
checkbox is not available if a PV source is defined on the 
Connections tab.
Parameter Description
PV Minimum and 
Maximum
Enter the percent range of the Transfer Function Input. 
These percent values define the range of the input 
value; regardless of the varying input value from the 
source or Transfer Function parameters, the input 
value always stays in this range. This percent range 
affects the Noise and sine wave amplitude.
OP Minimum and 
Maximum
Enter the range of the Transfer Function Output. These 
values define the range of the output; regardless of the 
input or Transfer Function parameters, the output 
always stays in this range. This range affects the Noise 
and sine wave amplitude.5-269
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5-270 Transfer Function
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ThThe Noise group contains the following parameters:
Integrator Page
The Integrator page consists of the Active Transfer Function 
group and Integrator Parameters group.
The Integrator Transfer Function requires only one parameter, 
the T (Integrator Period) located in the Integrator Parameters 
group:
The unit step response of the Integrator Transfer Function is
Parameter Description
PV (Std Dev %) Enter the Standard Deviation of the input noise as a 
percentage of the PV Range.
OP (Std Dev %) Enter the Standard Deviation of the output noise as a 
percentage of the PV Range. 
The noise follows a normal distribution.
 Figure 5.183
(5.37)
(5.38)
You can 
change the 
integrator 
period value 
in this field.
G 1
Ts
-----=
f t( ) t
T
--=5-270
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ThDelay Page
The Delay Page consists of the Active Transfer Function group 
and Delay Parameters group.
The Delay Parameters group contains of two input fields the K 
(Gain) and T (Delay Period) that are two parameters of the 
Delay Equation. 
The Delay Equation is defined as:
where:  
to = dead time
The inverse Laplace Transform of the Delay Equation multiplied 
by the general function F(s) is equal to Kf(t-to). This is shown 
below:
 Figure 5.184
(5.39)
(5.40)
G Ke
tos–
=
L 1– Ke
tos–
F s( )( ) Kf t to–( )=5-271
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ThDelay can be used in combination with the other Transfer 
function terms, by selecting the Delay checkbox in the Active 
Transfer Function group.
Lag Page
The Lag page allows you to simulate the response of a first-
order or second-order lag. A second order lag can be defined on 
the Lag page creating two first-order lags.
The Lag page contains the Lag 1 Parameters group and Lag 2 
Parameters group; with each group defining a single-order lag 
transfer function. The group contains two fields the K (Gain) and 
T (Time Constant).
The Lag Equation is defined as follows:
 Figure 5.185
(5.41)G K
Ts 1+
--------------=5-272
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Thwhere:  
G = transfer function
K = gain
T = time constant (t)
s = Laplace Transform variable
The time constant is the time required for the response to reach 
63.2% of its final value.
The unit step response of the Lag Equation is:
Lead Page
The Lead page allows you to define either a first or second order 
Lead transfer function. This is done via the two groups the Lead 
1 Parameters group and Lead 2 Parameters group. Both groups 
allow for the definition of the two terms of the Lead Equation K 
(5.42)
A second-order Lag may also be defined on the 2nd Order 
page. This second-order Lag is defined using variables K, T, 
and .
K 1 e–
t
T
--–
⎝ ⎠
⎜ ⎟
⎛ ⎞
Refer to the section on 
the 2nd Order Page for 
more information.
ξ
5-273
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5-274 Transfer Function
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Thand T.
The Lead Equation is defined as:
where:  
K = gain 
T = time constant
The Inverse Laplace Transform of the Lead Equation multiplied 
by the general function F(s) is:
A first or second-order Lead can be simulated by making one or 
both Lead Parameters active. You can make a set of K and T 
active by selecting the Lead checkbox in the Active Transfer 
 Figure 5.186
(5.43)
(5.44)
G K Ts 1+( )=
L 1– K Ts 1+( )F s( )[ ] K df t( )
dt
-----------T f t( )+=5-274
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ThFunctions group.
The response is an exponential curve of the following form:
where:  
K = process gain
T = time constant
The time constant is the time required for the response to reach 
63.2% of its final value. In this case, the time constant is 600s 
(10 minutes), so the response should have a value of about 63 
kgmole/h 10 minutes after the step change in Input is 
introduced. This is illustrated in the Strip Chart.
(5.45)Flow t( ) K 1 e
t
T
--–
–
⎝ ⎠
⎜ ⎟
⎛ ⎞
=
5-275
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5-276 Transfer Function
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Th2nd Order Page
The 2nd Order page allows you to define either the second order 
or sine wave function.
Standard Second Order
Select the Lag radio button in the 2nd Order Functionality 
Selection group, which is used to simulate the response of a 
standard Second Order process.
The Second Order Lag is defined as:
where:  
 = damping factor (or damping ratio)
The form of the Inverse Laplace Transform of this function 
depends on whether the Damping factor  is less than, equal to, 
or greater than one. The Inverse Laplace Transform is relatively 
complex and is not shown here.
 Figure 5.187
(5.46)G K
T 2s2 2Tξs 1+ +
--------------------------------------=
ξ
ξ
5-276
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ThA standard second-order Lead or Lag transfer function may or 
may not produce an oscillatory output, depending on the 
damping factor  (“Xi”). If the damping factor is unity, the 
response is said to be critically damped. If >1, the process is 
overdamped, producing a slower response than the critically 
damped case. If <1, the process is underdamped, producing 
the faster response. However, the response overshoots the 
target value, and oscillates with a period T.
Select the 2nd Order checkbox to simulate the Second Order 
Process. 
Sine Wave
The Sine Wave Transfer function is defined as follows:
where:
 = frequency of oscillation
First Order, Delay, and Ramp Functions can also be active, in 
which case all equations are superimposed.
 Figure 5.188
(5.47)
ξ
ξ
ξ
G Kω
s2 ω2+
-----------------=
ω
5-277
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5-278 Transfer Function
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ThK = amplitude
The frequency is the inverse of the period (  = 1/T).
The Inverse Laplace of the Sine Wave Transfer Function is:
The K-value (transfer function gain) is the amplitude of the sine 
wave, in a percentage of the Signal range. The range is the 
difference between the Signal Minimum and Maximum values 
given on the Configuration page.
As usual, select the Sine Wave radio button on the 2nd Order 
page to simulate the Sine Wave. You cannot activate both the 
Standard 2nd Order and the Sine Wave at the same time.
Ramp Page
The Ramp Page allows you to ramp the output value (OP) 
linearly in a transfer function.
(5.48)
 Figure 5.189
ω
f t( ) K ωtsin=5-278
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ThThe Ramp Parameters group contains the following parameters:
• Ramp Magnitude. Allows you to specify the amount of 
ramp either as a magnitude in the OP units, or as a 
percentage of the OP range. A positive ramp magnitude 
represents an increase in signal, whereas a negative 
value represents a decrease in signal.
• Ramp Duration. Allows you to specify the total amount 
of time required for the ramp function to change the OP.
• Current Offset. Displays the amount of deviation 
between the original OP, and the ramped OP.
You can execute the Ramp by clicking on the Start Ramp button. 
The status of the ramp is shown in the ramp status bar. Once 
the ramp is running, the Start Ramp button automatically 
changes to a Stop Ramp button. You can stop the ramp at any 
given time by clicking on the Stop Ramp button. As the ramp is 
executing, the Ramp Magnitude, and Ramp Duration start 
approaching to zero. When the Ramp Duration reaches zero, the 
ramp stops. You can reset the OP to the original value (before 
ramped) by clicking on the Reset Ramp button.
Rate Limiter Page
The Rate Limiter page allows you to specify the maximum rate 
of change of the OP.
 Figure 5.190
Ramp status bar5-279
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5-280 Transfer Function
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ThThe Rate Limiter analyzes the signal transformation in the 
transfer function, and limits the OP to change by a user-
specified maximum. The OP is restricted to change faster than 
the preset maximum. Therefore, any abrupt changes in the 
input signals can be intercepted, and smoothed.
To set the maximum rate of change of the OP, you can specify 
one of the following parameters in the Rate Limiter Parameters 
group:
• Max Rate of Change (/min). Allows you to specify the 
magnitude of the maximum rate of change in the OP 
units.
• Max Rate of Change (%/min). Allows you to specify 
the percentage of the maximum rate of change in the OP 
range.
5.12.4 Stripchart Tab
The Stripchart tab allows you to select and create default strip 
charts containing various variable associated to the operation. 
5.12.5 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.5-280
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Th5.13 Common Options
5.13.1 ATV Tuning Technique
The ATV (Auto Tune Variation) Technique is one of a number of 
techniques used to determine two important system constants 
known as the Ultimate Period, and the Ultimate Gain. From 
these constants, tuning values for proportional, integral, and 
derivative gains can be determined.
A small limit-cycle disturbance is set up between the Control 
Output and the Controlled Variable, such that whenever the 
process variable crosses the set point, the controller output is 
changed. The ATV Tuning Method is as follows:
• Determine a reasonable value for the valve change (OP). 
Let h represent this value. In HYSYS, h is 5%.
• Move the valve +h%.
• Wait until the process variable starts moving, then move 
valve -2h%.
• When the PV crosses the set point, move the OP +2h%.
• Continue this procedure until the limit-cycle is 
established.
From the cycle, two key parameters can be observed:    
The Tuning option only sets up the limit cycle; it does not 
calculate the tuning parameters for you.
To set up a Strip Chart to track the PV and OP do the following:
1. To open the Databook property view, press CTRL D.
2. On the Variables tab, add the PV and OP to the Variable List.
3. On the Strip Charts tab, add a Strip Chart and activate the PV and OP.
4. View the Strip Chart.
Observed Parameter Description
Amplitude (a) The amplitude of the PV curve, as a fraction of the 
PV span.
Ultimate Period (PU) Peak-to-Peak period of the PV curve.5-281
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ThThe Ultimate Gain can be calculated from the following 
relationship:
where:  
KU = ultimate gain
 h = change in OP (0.05)
 a = amplitude
Finally, the Controller Gain and Integral Time can be calculated 
as follows:
Controller Gain = KU / 3.2
Controller Integral Time = 2.2*PU
5.13.2 Controller Face Plate
There are two ways that you can access the controller Face 
Plate:
1. In the menu bar select Tools | Face Plates command, or 
press CTRL F. 
The Face Plates property view appears.
2. From the list of available flowsheets, select the flowsheet 
that contains the logical operation you want to view the face 
plate for.
3. From the list of available logical operations, select the logical 
operation you want to view the face plate for.
4. Click the Open button. The Face Plates property view closes 
and the face plate for the selected logical operation appears.
OR
(5.49)
The ATV Tuning Method only works for systems with dead 
time.
KU 4h
πa
-----=
Refer to Section 11.8 - 
Face Plates in the 
HYSYS User Guide for 
more information.5-282
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Th1. Open the property view of a Controller operation. 
2. Click the Face Plate button located at the bottom of the 
Controller’s property view.
Each controller’s Face Plate varies in appearance, however the 
functionality remains the same. This section provides a general 
description of how to use the controller Face Plate.
The Face Plate provides all pertinent information about the 
controller when the simulation is running. The Setpoint is shown 
as a red pointer, and the actual value of the Process Variable 
appears in the current default unit. Output is always displayed 
as a percentage of the span you defined on the Valve tab. The 
Face Plate also displays the execution type and the setpoint 
source.
Also, you can change the mode of the Controller by selecting the 
mode from the drop-down list at the bottom left of the Face 
Plate. The mode choices are identical to those on the 
Parameters tab. Clicking the Tuning button returns you to the 
Tuning tab of the Controller property view. 
 Figure 5.191
Click the Parameters button 
to return to Parameters tab 
of the Ratio/Split Range 
Control property view.
The drop-down list contains 
three controller mode 
options: Off, Manual, and 
Automatic.
Click the up and 
down arrows to 
access the first 
and second 
variables.
The execution 
type is shown as 
either Int 
(Internal) or Ext 
(external).
The setpoint is 
shown as either L 
(local) or R 
(Remote).
Setpoint
The shaded bar 
indicates the value 
of the Process 
Variable/Controller 
Output in a 
percentage of the 
PV/OP range, and 
the number is the 
actual PV/OP.5-283
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5-284 Common Options
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ThChanging the Setpoint and Output
You can change the SP or OP of the Controller (depending on the 
current mode) at any time during the simulation without 
returning to the Parameters tab, by using the Face Plate.
To change the SP while in Automatic mode, or to change the OP 
while in Manual mode, use any one of the following three 
methods:
1. Move to the field for the parameter you want to change. 
For this example, the Setpoint (top field) is changed. Start 
entering a new value for the SP, and HYSYS displays a field 
with a drop-down list containing the default units. Once you 
have entered the value, press ENTER and HYSYS accepts 
the new Setpoint. 
 Figure 5.192
 Figure 5.193
Setpoint
This shaded bar and 
number indicate the 
value of the 
Controller Output 
(valve opening) in 
percent.Select this button to 
return to the Controller 
Tuning property view.
The shaded bar 
indicates the value 
of the Process 
Variable in a 
percentage of the PV 
range, and the 
number is the actual 
PV.
The current 
Controller mode.
The execution type is 
shown as either Int 
(Internal) or Ext 
(external).
The setpoint is 
shown as either L 
(local) or R 
(Remote).5-284
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Th2. Place the mouse pointer near the red Setpoint indicator, and 
the cursor changes to a double-ended arrow. Click and hold, 
a fly-by appears below, showing the current value of the SP 
(in this case, 50%). 
3. Click and drag the double-ended arrow to the new SP of 
60%. The fly-by displays the SP value as you drag. Release 
the mouse button to accept the new SP.
4. Place the pointer at either end of the field, and the pointer 
changes to a single-ended arrow. Click once to increase or 
decrease the value by 1%. For example, switch to Manual 
mode and adjust the OP. To increase the OP, move the 
pointer to the right end of the field and the single-ended 
arrow pointing to the right appears. Click to increase the OP 
by 1%. 
If you select an alternate unit, your value appears in the face 
plate using HYSYS display units.
 Figure 5.194
You can click the button consecutively to repeatedly increase 
(or decrease) the OP.
Position the pointer near the SP 
indicator, and the double-ended 
arrow appears. Click and hold, 
a fly-by appears, showing the 
current value of the SP.
Click and drag the 
arrow to the new SP 
location. The fly-by 
shows the SP as it 
changes.
Release the mouse button 
and the SP indicator 
moves to the new SP.5-285
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ThObject Inspect Menu of Face Plates
The Object Inspect menu for a Fixed Size Face Plate is shown in 
the figure below.
The options associated with this menu are:
The additional menu options in the Object Inspection menu for a 
Scalable Face Plate are:
 Figure 5.195
Command Description
Turn Off Turns the Controller Mode to Off.
Start Ramp Starts Setpoint Ramping
Auto-Tune Puts the Controller into a cycling mode. This can be 
used for tuning the Controller.
Tuning Returns you to the Tuning page of the Controller 
property view.
Connections Returns you to the Connections page of the Controller 
property view.
Parameters Returns you to the Parameters page of the Controller 
property view.
Print Datasheet Allows you to print the Datasheet for the controller.
Print Specsheet Allows you to print the controller Specsheet.
Command Description
Font Allows you to choose the Font for the text on the Face 
Plate.
Hide Values/
Show Values
Hides the values for SP, PV, and OP. When the values 
are hidden, the Show Values option appears. Choose 
this to display the values. 
Hide Units/Show 
Units
Hides the units for SP and PV. When the units are 
hidden, the Show Units option appears in the menu. 
Choose this to display the units.
Refer to Chapter 3 - 
Control Theory in the 
HYSYS Dynamic 
Modeling guide for 
information on the 
object inspection 
options.5-286
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Piping Operations 6-1
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Th6  Piping Operationsw.cadfamily.com    EMa
e document is for study 6.1  Compressible Gas Pipe................................................................... 1
6.1.1  Compressible Gas Pipe Property View.......................................... 5
6.1.2  Design Tab .............................................................................. 6
6.1.3  Rating Tab............................................................................... 9
6.1.4  Worksheet Tab ....................................................................... 11
6.1.5  Performance Tab .................................................................... 12
6.1.6  Properties Tab........................................................................ 13
6.1.7  Dynamics Tab ........................................................................ 14
6.2  Liquid-liquid Hydrocyclone........................................................... 16
6.2.1  Liquid-liquid Hydrocyclone Property View................................... 23
6.2.2  Design Tab ............................................................................ 24
6.2.3  Worksheet Tab ....................................................................... 30
6.2.5  Dynamics Tab ........................................................................ 34
6.2.6 Nomenclature ......................................................................... 34
6.3 Mixer............................................................................................. 35
6.3.1  Mixer Property View................................................................ 36
6.3.2  Design Tab ............................................................................ 37
6.3.3  Rating Tab............................................................................. 40
6.3.4  Worksheet Tab ....................................................................... 40
6.3.5  Dynamics Tab ........................................................................ 40
6.4  Pipe Segment............................................................................... 43
6.4.1  Pipe Segment Property View .................................................... 50
6.4.2  Design Tab ............................................................................ 51
6.4.3  Rating Tab............................................................................. 66
6.4.4  Worksheet Tab ....................................................................... 83
6.4.5  Performance Tab .................................................................... 83
6.4.6  Dynamics Tab ........................................................................ 896-1
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The document is for study 6.4.7  Deposition Tab........................................................................92
6.4.8  Profes Wax Method..................................................................95
6.4.9  Modifying the Fittings Database ..............................................105
6.5  Relief Valve.................................................................................110
6.5.1  Relief Valve Property View......................................................110
6.5.2  Design Tab ...........................................................................111
6.5.3  Rating tab............................................................................114
6.5.4  Worksheet Tab......................................................................118
6.5.5  Dynamics Tab.......................................................................118
6.6  Tee .............................................................................................122
6.6.1  Tee Property View .................................................................123
6.6.2  Design Tab ...........................................................................124
6.6.3  Rating tab............................................................................127
6.6.4  Worksheet Tab......................................................................128
6.6.5  Dynamics Tab.......................................................................128
6.7  Valve ..........................................................................................131
6.7.1  Valve Property View ..............................................................133
6.7.2  Design Tab ...........................................................................134
6.7.3  Rating Tab............................................................................135
6.7.4  Worksheet Tab......................................................................147
6.7.5  Dynamics Tab.......................................................................147
6.8  References..................................................................................1586-2
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Th6.1 Compressible Gas Pipe
The Compressible Gas Pipe (CGP) model uses an algorithm that 
solves a vector system using the Two-Step Lax-Wendroff 
method with Boris & Book anti-diffusion.
The CGP unit operation is primarily designed for transient 
calculations with streams. Steady state calculations have been 
implemented primarily for initialization of the Pipe State prior to 
transient calculations.
The following calculation modes are supported in steady sate 
mode:
• Specify Inlet Pressure, Temperature, and Mass Flow
• Specify Inlet Temperature, Mass Flow, and Outlet 
Pressure
• Specify Inlet Pressure and Temperature, and Outlet 
Pressure. Alternatively the pressure drop may be used 
with either boundary pressure.
Model for a Single Phase 
Compressible Flow
The following equations are used in HYSYS to model a single 
phase compressible flow.
Governing Equations
• Mass:
(6.1)Aρ( )∂
t∂
-------------- Aρu( )∂
x∂
-----------------+ 0=6-3
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Th• Momentum:
• Energy:
where:  
A= , pipe cross-sectional area
E = , total internal energy
H = , total enthalpy
S = , the pipe perimeter
D = pipe diameter
e = internal energy
f = friction factor
g = acceleration due to gravity
h = enthalpy
k = heat transfer coefficient
p = pressure
t = time
T = temperature
Twall = wall temperature
(6.2)
(6.3)
ρu( )∂
t∂
------------- ρu2 p+( )∂
x∂
-------------------------+ ρgsinθ 1
2
--fρu u S
A
--– ρu2 1
A
---dA
dx
------–=
ρE( )∂
t∂
-------------- ρHu( )∂
x∂
------------------+ k Twall T–( )S
A
--- ρ– gsinθ 1
2
--fρu2 u S
A
---– ρHu 1
A
-- dA
dx
------–=
1
4
--πD2
e 1
2
--u2+
h 1
2
--u2+
πD6-4
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Thu = velocity
x = distance
 = pipe inclination
 = density
Algorithm
The algorithm solves the vector system by the Two-Step Lax-
Wendroff method with Boris & Book anti-diffusion.
6.1.1 Compressible Gas Pipe 
Property View
There are two ways that you can add a Compressible Gas Pipe to 
your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing  
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select 
Compressible Gas Pipe.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Compressible Gas Pipe icon.
(6.4)
θ
ρ
U∂
t∂
------ D∂
x∂
------+ G=
Compressible Gas Pipe 
icon6-5
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6-6 Compressible Gas Pipe
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ThThe Compressible Gas Pipe property view appears.
6.1.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 6.16-6
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ThConnections Page
On the Connections page, you must specify the Feed and 
Product material streams.
You can specify the streams by either typing the name of the 
new stream or selecting existing streams in the Inlet and Outlet 
drop-down lists. You can also edit the name of the operation on 
this page.
 Figure 6.2
The Compressible Gas Pipe does not support an energy 
stream.6-7
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6-8 Compressible Gas Pipe
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ThParameters Page
The Parameters page allows you to specify the pressure drop 
across the pipe as well as the name of the operation. 
There are also three calculated values that are displayed on the 
page.
• Max. Mach Number. For steady state calculations this is 
always at the outflow from the pipe. During dynamic 
calculations this can be at any location within the pipe.
• Max. Pressure. For steady state calculations this is 
always at the outflow from the pipe. During dynamic 
calculations this can be at any location within the pipe.
• Max. Velocity. For steady state calculations this is 
always at the outflow from the pipe. During dynamic 
calculations this can be at any location within the pipe.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
 Figure 6.3
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-8
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Th6.1.3 Rating Tab
The Rating tab consists of two pages:
• Sizing. you provide information regarding the 
dimensions of sections in the pipe segment
• Heat Transfer. the heat loss of the pipe segment can 
either be specified or calculated from various heat 
transfer parameters.
Sizing Page
On the Sizing page, the length-elevation profile for the CGP is 
constructed. You can provide details for each fitting or pipe 
section that is contained in the CGP that you are modeling. An 
unlimited number of pipe sections or fittings can be added on 
this page.
For a given length of pipe which is modelled in HYSYS, the 
parameters of each section is entered separately. To fully define 
the pipe section, you must also specify pipe schedule, diameters 
(nominal or inner and outer), a material, and a number of cells.
There are two ways that you can add sections to the length-
elevation profile:
• Click the Add Section button, which allows you to add 
the new section after the currently selected section.
• Click the Insert Section button, which allows you to add 
the new section before the currently selected section
 Figure 6.46-9
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ThFor each segment that you add, you must specify the following: 
• Length. The physical length of the pipe. Notice that it is 
not appropriate to enter an equivalent length and 
attempt to model fittings.
• Elevation Change. The elevation change of the pipe.
• Cells. Number of cells within the pipe (10 - 1000).
When modeling multiple sections, faster and more stable 
convergence can be obtained if all cell sizes are similar. For a 
stable solution, the number of cells should be selected such that 
the following constraint is met: 
To delete a section, click the section you want to delete and click 
the Delete button. The Clear Profile button deletes all sections 
except for the first section. However, all data for the first section 
is cleared.
The Overall Dimensions group manages the pipe diameter and 
material data. This works in the same fashion as the standard 
Pipe Segment unit operation.
(6.5)
The cells have to be sufficiently small to ensure that in any 
one time step there will be changes of sufficient magnitude 
in a sufficient number of cells to ensure that the solver used 
by the Compressible Gas pipe and the HYSYS dynamics 
pressure-flow solver interact correctly.
The external diameter is not currently used by the 
calculations. It has been added so that the heat transfer 
models can be more easily enhanced in future versions.
Cell Length
Time Step
--------------------------- 0.5 Sonic Velocity<
Refer to Section 7.3 - 
Pipe Segment for more 
information.6-10
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Piping Operations 6-11
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ThHeat Transfer Page
A simplified heat transfer model is used that allows you to 
specify the ambient temperature and an overall heat transfer 
coefficient.
6.1.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
 Figure 6.5
The Ambient Temperature is the bulk ambient temperature, 
and Overall HTC is the overall heat transfer coefficient based 
upon the outside diameter of the pipe.
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-11
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6-12 Compressible Gas Pipe
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Th6.1.5 Performance Tab
This tab is functionally similar to the Performance tab on the 
standard Pipe Segment unit operation.
You can view a complete profile by clicking on the View Profile 
button. The properties displayed on the Table tab of the Profile 
property view are listed below:
• Axial Length
• Pressure
• Temperature
• Mass Flow
• Velocity
• Mach Number
• Mass Density
• Internal Energy
• Enthalpy
• Speed Of Sound
 Figure 6.6
Refer to Section 7.3 - 
Pipe Segment for more 
information.6-12
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Th6.1.6 Properties Tab
Due to the number of physical property calculations, an 
acceptable calculation speed is not possible by directly calling 
the current property package for the flowsheet. Three 
alternative methods are available from the drop-down list:
• Perfect Gas
• Compressible Gas
• Table Interpolation
The methods are described in the sections below.
Perfect Gas
Compressible Gas
Same as for perfect gas, but 
The compressibility factor, Z is calculated from the current 
property package for the flow sheet at the average conditions 
within the pipe.
Table Interpolation
A neural network calculates physical properties. This neural 
network uses a Radial Basis Function to train the network from 
physical properties, predicted from the current property 
package of the flowsheet.
(6.6)
(6.7)
(6.8)
H Cp TΔ=
ρ PMW
RT
-------------=
ρ PMW
ZRT
-------------=6-13
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6-14 Compressible Gas Pipe
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ThPrior to calculations, you must train the neural network. The 
Table Generation group manages the extent of the training. 
6.1.7 Dynamics Tab
The Dynamics tab contains the following pages: 
• Specs
• StripChart
Specs Page
For transient compressible flow calculations, the solution of 
pressure/flow equations is inappropriate since the boundary 
pressure is not directly related to flow. It is however critical that 
the compressible gas solve simultaneously with the other 
flowsheet equations. This is achieved by making perturbations 
at each end of the pipe for each time step and re-evaluating the 
change in state over the time step. These changes are then fit to 
an equation of the following form, which is passed to the 
Pressure Flow solver: 
 Figure 6.7
Care must be taken to train over the full extent of the 
expected range of operating conditions since extrapolation 
always yield unpredictable results.
(6.9)A.Pres BFlow2 CFlow D+ + + 0=6-14
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ThThe Pressure Flow Equations group displays the values for the 
coefficients in the above equation, which are continuously 
updated at each time step.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
 Figure 6.8
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.6-15
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6-16 Liquid-liquid Hydrocyclone
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Th6.2 Liquid-liquid 
Hydrocyclone
The HYSYS Liquid-liquid Hydrocyclone predicts the performance 
of an oily water cleaning unit operation. The Liquid-liquid 
Hydrocyclone generates results based on the Migration 
Probability Theory. An oil droplet size distribution based on a 
sauter mean diameter is applied and the resulting volume of oil 
separated is calculated.
The Liquid-liquid Hydrocyclone is designed to be easy to use 
with a single input tab giving liner details and the oil droplet 
distribution. Process details, Hydrocyclone liner dimensionless 
parameters, and separation performance are calculated. You 
have the option of modelling three different types of liner: 
• Vortoil G-liners
• Serck Baker Oilspin liners
• Custom liners
The fundamental calculation methods are similar for all the 
liners. The hydraulic parameters however vary considerably.
Theory
The Liquid-liquid Hydrocyclone operation performs the following 
calculations to generate the results:
• Oil Droplet Distribution
• Hydrocyclone Liner Dimensions
• Hydrocyclone Hydraulics
• Oil Droplet Migration Probability
• Hydrocyclone Separation Efficiency6-16
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ThOil Droplet Distribution
The Liquid-liquid Hydrocyclone uses a Rosin Rammler Oil Droplet 
Distribution to describe the dispersion at the Inlet. A two 
parameter Cumulative Distribution is defined. 
The Cumulative Distribution is defined by the following 
equation:
where:
F(d) = cumulative distribution
d = droplet diameter
drm = Rosin Rammler modal diameter
n = exponential power index
The Rosin Rammler modal diameter drm can be related to 
another mean diameter dM by the following equation.
where:  
f(d) = fraction undersize at diameter dM
(6.10)
(6.11)
F d( ) 1 d
drm
--------⎝ ⎠
⎛ ⎞ n
–⎝ ⎠
⎛ ⎞exp–=
dM drm 1 f d( )–( )ln–[ ]1 n⁄×=6-17
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6-18 Liquid-liquid Hydrocyclone
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ThHydrocyclone Liner Dimensions
The Hydrocyclone Dimensions are based on the following 
variables:
• Dimensions Schematic
• Characteristic Diameter (D). The Hydrocyclone 
characteristic diameter is defined by the user.
• Inlet Diameter (DIN). The Inlet diameter is set at 0.35D.
• Underflow Diameter (DW). The Underflow diameter is set 
at 0.50D.
• Overflow Diameter (DO). The Overflow diameter is 
defined by the user.
• Taper Angles. The Taper angles  and  define the 
Separation section geometry.
 Figure 6.9
L1
L2
L3
L4
2D
D
D/2
θ1
θ2
DIN DO
DW
θ1 θ26-18
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Th• Lengths. The length of each taper section is calculated 
from the Taper angles (  and ) and the characteristic 
diameter (D). The length from the end of the taper 
section to the liner tip is taken as 20D. These lengths are 
then summed to give a total liner Length (L).
Hydrocyclone Hydraulics
The Hydrocyclone can be modelled Hydraulically in a dimensionless 
manner assuming geometrically similar criteria. A Reynolds 
number and Hydrocyclone number can be defined using 
dimensions, fluid parameters, and operating conditions. Split 
Ratio and Maximum flow are also determined from the operating 
data.
• Reynolds Number. ReD is expressed as:
where:  
QT = volumetric flow rate
 = continuous phase density
DH = Hydrocyclone Characteristic Diameter
 = continuous phase viscosity
• Hydrocyclone Number. Hy75 relating to an oil droplet 
diameter d'75 may be defined as:
(6.12)
(6.13)
θ1 θ2
ReD
QT ρc×
900 π DH μc×××
--------------------------------------------=
ρc
μc
Hy75
QT Δρ d′75
2××
3600 DH
3 μc××
----------------------------------------=6-19
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6-20 Liquid-liquid Hydrocyclone
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Thwhere:  
QT = volumetric flow rate
 = oil and water density difference
d'75 = 75% Migration Probability Droplet Diameter
DH = Hydrocyclone Characteristic Diameter
 = continuous phase viscosity
The Hydrocyclone Number can also be related to the 
Reynolds number for similar geometric units by means of 
the following general equation:
Experimental or Production performance data can be 
used to establish the values of a and b. These constants 
are Liner specific.
• Split Ratio. Split Ratio is calculated from the user defined 
Pressure Differential Ratio (PDR) by means of a quadratic 
expression:
where:  
 = parameter values established from a curve fit to 
operating data
• Maximum Flowrate. Maximum flow rate for the system is 
related to the pressure differential between the Inlet and 
Reject streams:
where:  
nL = number of Liners
PIN = Inlet pressure
PREJ = Overflow pressure
k, n = constant values established from hydraulic data
(6.14)
(6.15)
(6.16)
Δρ
μc
Hy75 a ReD( )b=
F α PDR( )2 β PDR( ) γ+ +=
α β γ,,
QMAX nL k PIN PREJ–( )n×=6-20
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ThOil Droplet Migration Probability
The method of Dense Dispersion Hydrocyclones is applied to predict 
the volume of oil separated from the Inlet stream. A Migration 
Probability for the droplet distribution is derived from statistical 
theory and a Reduced Migration Probability.
• Migration Probability. For a given Inlet oil droplet 
distribution the Migration Probability (MP) of a droplet of 
diameter d microns is defined as the chance that it will 
be separated in the oil overhead stream. The MP can be 
related to the Reduced Migration Probability (RMP) and 
the Split Ratio (F) by the following expression:
• Reduced Migration Probability. An analytical function may 
be fitted to represent the centre of an envelope of 
experimental curves for a particular liner. This Reduced 
Migration Probability (RMP) can be represented generally 
in terms of a normalised droplet diameter  as:
where:  
a, b, c = constants determined by experiment
 dimensionless droplet diameter
d'75 = determined from the Hydrocyclone Number
d = droplet diameter from the Distribution
(6.17)
(6.18)
MP d( ) RMP d( ) 1 F–( )× F+=
Δ75
RMP 1 a Δ75 b–[ ]c( )exp–=
Δ75
d
d′75
---------=6-21
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6-22 Liquid-liquid Hydrocyclone
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Th• Graphical Representation. The Migration Probability for 
an Oil Droplet Distribution is represented graphically as:
Hydrocyclone Separation Efficiency
The Separation Efficiency ( ) of the Hydrocyclone vessel is 
calculated from the under flow oil concerntration and inlet 
stream oil concentrations:
where:  
Ci = inlet stream oil concentration (ppm)
 = under flow oil concentration (ppm)
vliq = inlet liquid oil volume flow rate
vof = over flow oil volume flow rate
vuf = under flow volume flow rate
 Figure 6.10
(6.19)
ε
ε 100 1
Cuf
Ci
-------–⎝ ⎠
⎛ ⎞=
Cuf 1000000
vliq vof–
vuf
--------------------×=6-22
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Th6.2.1 Liquid-liquid 
Hydrocyclone Property 
View
There are two methods to add a Liquid-liquid Hydrocyclone to 
your simulation:
3. From the Flowsheet menu, click Add Operation. The 
UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
4. Click the Upstream Ops radio button.
5. From the list of available unit operations, select Liquid-
liquid Hydrocyclone.
6. Click the Add button.
The Liquid-liquid Hydrocyclone property view appears.
In the case when no oil is in the under flow, the separation 
efficiency is 100%
 Figure 6.116-23
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6-24 Liquid-liquid Hydrocyclone
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Th• To delete the Liquid-liquid Hydrocyclone operation, click 
the Delete button. HYSYS will ask you to confirm the 
deletion.
You can also delete a Liquid-liquid Hydrocyclone by 
clicking on the Liquid-liquid Hydrocyclone icon on the 
PFD and pressing DELETE.
• To ignore the Liquid-liquid Hydrocyclone during 
calculations, select the Ignored checkbox. HYSYS 
completely disregards the operation (and cannot 
calculate the outlet stream) until you restore it to an 
active state by clearing the checkbox.
6.2.2 Design Tab
The Design tab consists of the following pages:
• Connections
• Parameters
• Liner Details
• Droplet Distribution
• User Variables
• Notes
Connections Page
The Connections page is used to define all of the connections to 
the Liquid-liquid Hydrocyclone. 
You can specify the inlet stream, overflow outlet stream, and 
underflow outlet stream attached to the operation. The name of 
 Figure 6.126-24
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Ththe operation can be changed in the Name field. 
You can select a different fluid package associated to the Liquid-
liquid Hydrocyclone using the Fluid Package drop-down list.
Parameters Page
The Parameters page allows you to specify the Liquid-liquid 
Hydrocyclone operation parameters. 
The following table lists and describes the parameters available 
in the Parameters page:
 Figure 6.13
Object Description
Liner Type drop-
down list
Allows you to choose between three types of Vessel 
liner:
• Vortoil G-Liners
• Serck Baker Oil Spin
• Custom Liners
Hydraulic parameters and physical Dimensions change 
between the three types of Liner.
Number of Liners 
cell
Allows you to specify the number of active vessel 
liners. 
Min. Flowrate 
cell
Displays the minimum flow rate per liner depending on 
the selected Liner type.
• Vortoil recommends a minimum value of 2m3/hr 
for the G-Liner.
• Serck Baker recommends a minimum value of 
4m3/hr for the OilSpin Liner.
• Custom liner remains unchanged.
Min. Reject 
Pressure cell
Allows you to specify the minimum Oil Overflow 
(Reject) downstream pressure.6-25
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6-26 Liquid-liquid Hydrocyclone
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ThAdvanced Parameters
You cannot modify the coefficients of Vortoil G-liner nor Serck 
Baker Oil Spin, but you can view them on the Advanced 
Parameters page.
The Vortoil G-liner will display the coefficients for Vortoil G-liner, 
and Serck Baker Oil Spin will display the coefficients for Serck 
Baker Oil Spin. However, if you choose Custom Liner, you can 
modify some of the coefficients.
The following table illustrates how the coefficients on the Liners 
Details page react to your input: 
PDR cell Allows you to specify the Pressure Differential Ratio. 
The PDR is the ratio of the following stream pressure 
drops:
Split Ratio cell Allows you to specify the volume percent of the total 
inlet stream that passes to the overflow stream.
Underflow DP 
cell
Allows you to specify the pressure difference between 
the inlet stream and the underflow stream.
Underflow 
Pressure cell
Displays the pressure of the underflow stream.
Advanced 
Parameters
Allows you to view coefficients of selected liners as well 
as enter coefficients when Custom Liner is selected. 
Function Result
If you choose Custom Liner, then all numbers will remain 
unchanged, but the Characteristic 
Diameter and the Overflow Diameter 
become blue, and the remaining 
numbers become red.
If you change the Characteristic 
Diameter,
then the red default numbers will 
update according to calculations.
If you modify one of the red 
default numbers,
then that value becomes blue and 
will no longer update according to 
the code.
If you subsequently delete the 
blue number, 
then that number will be replaced by 
the calculated number and appear in 
red.
If Upper Taper Angle and Lower 
Taper Angle are deleted, 
then they will automatically return to 
the default values, 20 and 1.5.
Object Description
PDR Inlet Pressure Overflow Pressure–
Inlet Pressure Underflow Pressure–
--------------------------------------------------------------------------------------=6-26
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ThIf you delete the Characteristic 
Diameter on the overflow 
diameter,
then the values will go empty as well 
as all red numbers because there in 
no way to calculate the default data.
If you reselect one of the liners, 
Vortoil G-liner or Serck Baker Oil 
Spin liner, from the dropdown 
list,  
then any entries on the Liner Details 
and the Advanced Parameters page 
will be lost. 
If the parameter fields are 
empty,
then the status bar of the unit op 
should state the parameters are 
missing.
If the parameters are changed, then the newly entered coefficients 
will be recalculated.
Red numbers indicate a default coefficient.
Blue numbers indicate a coefficient specified by the user.
Black numbers indicate a coefficient that is unchangeable.
Function Result6-27
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6-28 Liquid-liquid Hydrocyclone
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ThLiner Details Page
The Liner Details page allows you to manipulate the selected 
Liner type.
The following table lists and describes the parameters available 
for modification in the Liner Details page:
 Figure 6.14
Object Description
Liner Type drop-
down list
Allows you to choose between two types of Vessel 
liner:
• Vortoil G-Liners
• Serck Baker Oil Spin
• Custom Liners
Hydraulic parameters and physical Dimensions 
change between the two types of Liner.
Characteristic 
Diameter cell
Allows you to specify the liner characteristic 
diameter, which is used to determine the diameter 
for the Inlet and Underflow.
Inlet Diameter cell Displays the calculated inlet diameter value.
Upper Taper cell Displays the upper taper angle. 
Lower Taper cell Displays the lower taper angle.
Overflow Diameter 
cell
Allows you to specify the Overflow diameter.
Underflow Diameter 
cell
Displays the calculated Underflow diameter based 
on the selected Liner type and the specified 
characteristic diameter.
Total Length cell Displays the Liner overall length of the selected 
Liner type’s hydrocyclone geometry.6-28
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ThDroplet Distribution Page
The Droplet Distribution page allows you to manipulate the 
Liquid-liquid Hydrocyclone performance, by modifying the 
dispersed oil droplet distribution.
The size distribution of oil droplets at the Hydrocyclone inlet is 
calculated using two parameters of the Rosin Rammler distribution. 
The Rosin Rammler distribution calculation is based on a mean 
droplet diameter and an exponential term power index. 
The following table lists and describes the distribution 
parameters:
Choose one of the two radio buttons on the Design page to 
receive either volume-based results or number-based results.
 Figure 6.15
Parameter Description
Droplet Sauter 
Mean
This is the droplet diameter whose volume to surface 
area ratio is the same as that of the distribution as a 
whole and so represents the surface area mean 
diameter.
Droplet d50 This is the diameter of droplet at the 50% undersize 
point on a cumulative volume distribution curve.
Droplet d95 This is the diameter of droplet at the 95% undersize 
point on a cumulative volume distribution curve.
Rosin Rammler 
Index
This is the power term to which the exponential part of 
the Rosin-Rammler Distribution is raised. Usually the 
value is between 1 and 2.5.6-29
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6-30 Liquid-liquid Hydrocyclone
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ThUser Variables Page
The User Variables page allows you to create and implement 
variables in the HYSYS simulation case.
Notes Page
The Notes page provides a text editor that allows you to record 
any comments or information regarding the specific unit 
operation, or the simulation case in general. 
6.2.3 Performance Tab
The Performance tab displays the calculated performance results 
of the Liquid-liquid Hydrocyclone.
General Page
The General page displays the calculated general Liner 
performance results.
• Inlet oil concentration in parts per million (ppm) by 
volume and mg/l
• Maximum flow rate for the vessel. This value is calculated 
from the Liner hydraulic characteristics.
• Droplet diameter separated with 75% efficiency at 
operating conditions
 Figure 6.16
For more information on 
implementing the User 
Variables, refer to 
Chapter 5 - 
User Variables in the 
HYSYS Customization 
For more information, 
refer to Section 
7.19 - Notes Manager in 
the HYSYS User Guide.6-30
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Piping Operations 6-31
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Th• Pressure drops at Overflow and Underflow relative to the 
Inlet
• System Reject Ratio
• System separation efficiency
Geometric Page
The Geometric page displays the calculated geometric Liner 
performance results.
• Hydrocyclone Reynolds Number based on the 
Characteristic diameter
• Hydrocyclone Number (Hy75)
Overflow Page
The Overflow page displays the calculated Overflow results.
 Figure 6.17
 Figure 6.186-31
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6-32 Liquid-liquid Hydrocyclone
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Th• Overflow pressure
• Volumetric flowrate
• Oil concentration in ppm
Underflow Page
The Underflow page displays the calculated Underflow results.
• Underflow pressure
• Volumetric flowrate
• Oil concentration in ppm and mg/l
 Figure 6.196-32
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Piping Operations 6-33
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ThTables Page
The Tables page displays the tabulated results of the Oil Droplet 
Distribution or the Migration Probability. To view either results select 
the appropriate radio button.
Plots Page
The Plots page displays in graph format the results of the Oil 
Droplet Distribution or the Migration Probability. To view either plot 
select the appropriate radio button.
 Figure 6.20
 Figure 6.216-33
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6-34 Liquid-liquid Hydrocyclone
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Th6.2.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
6.2.5 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
6.2.6 Nomenclature
The following Nomenclature has been adopted for the Liquid-
liquid Hydrocyclone calculations:
Variable Symbol Units
Volumetric Flowrate m3/hr
Maximum Volumetric Flowrate m3/hr
Inlet Pressure Bar
Overflow Pressure Bar
Underflow Pressure Bar
Continuous Phase Density kg/m3
Oil Droplet Density kg/m3
Hydrocyclone Characteristic 
Diameter
m
Continuous Phase Viscosity Pa.s
Droplet Diameter microns
Sauter Mean Droplet Diameter microns
50% Droplet Diameter microns
75% Droplet Diameter microns
95% Droplet Diameter microns
Refer to Section 
1.3.10 - Worksheet Tab in 
the HYSYS Operations 
Guide for more 
information.
QT
QMAX
PIN
PREJ
POUT
ρc
ρo
D
μc
d
d3 2,
d50
d75
d956-34
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Piping Operations 6-35
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Th6.3 Mixer
The Mixer operation combines two or more inlet streams to 
produce a single outlet stream. A complete heat and material 
balance is performed with the Mixer. That is, the one unknown 
temperature among the inlet and outlet streams is always 
calculated rigorously. If the properties of all the inlet streams to 
the Mixer are known (temperature, pressure, and composition), 
the properties of the outlet stream is calculated automatically 
since the composition, pressure, and enthalpy is known for that 
stream.
The mixture pressure and temperature are usually the 
unknowns to be determined. However, the Mixer also calculates 
backwards and determine the missing temperature for one of 
the inlet streams if the outlet is completely defined. In this latter 
case, the pressure must be known for all streams.
75% Migration Probability Droplet 
Diameter
microns
Dimensionless Droplet Diameter
Pressure Differential Bar
Separation Efficiency %
Inlet Oil Concentration ppm Vol.
Underflow Oil Concentration ppm Vol.
Split Ratio
Hydrocyclone Reynolds Number
Hydrocyclone Number
Number of Liners
Total Liner Length m
Upper Taper Angle degrees
Lower Taper Angle degrees
Variable Symbol Units
d′75
Δ75
ΔP
ε
Ci
Co
F
ReD
Hy75
nL
L
θ1
θ26-35
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6-36 Mixer
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ThThe Mixer flashes the outlet stream using the combined 
enthalpy. Notice that when the inlet streams are completely 
known, no additional information needs to be specified for the 
outlet stream. The problem is completely defined; no degrees of 
freedom remain.
The dynamic Mixer operation functions very similarly to the 
steady state Mixer operation. However, the enhanced holdup 
model and the concept of nozzle efficiencies can be applied to 
the dynamic Mixer. Flow reversal is also possible in the Mixer 
depending on the pressure-flow conditions of the surrounding 
unit operations.
6.3.1 Mixer Property View
There are two ways that you can add a Mixer to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select Mixer.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Mixer icon. 
The resultant temperature of the mixed streams may be 
quite different than those of the feed streams due to mixing 
effects.
Mixer icon6-36
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Piping Operations 6-37
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ThThe Mixer property view appears.
6.3.2 Design Tab
The Design tab provides access to the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 6.226-37
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6-38 Mixer
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ThConnections Page
On the Connections page, you can specify the following:
• any number of inlet streams to the mixer
• a single outlet stream
• name for the mixer
• fluid package associated to the mixer
Parameters Page
The Parameters page allows you to indicate the type of 
Automatic Pressure Assignment, HYSYS should use for the 
streams attached to the Mixer. 
 Figure 6.23
 Figure 6.246-38
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ThThe default is Set Outlet to Lowest Inlet, in which case all but 
one attached stream pressure must be known. HYSYS assigns 
the lowest inlet pressure to the outlet stream pressure.
If you specify Equalize All, HYSYS gives all attached streams the 
same pressure once one of the attached stream pressures are 
known. If you want to specify all of the inlet stream pressures, 
ensure first that all pressures have been specified before 
installing the Mixer, then choose Set Outlet to Lowest Inlet. In 
this case, there is no automatic pressure assignment since all 
the stream pressures are known.
If you are uncertain of which pressure assignment to use, 
choose Set Outlet to Lowest Inlet. Only use Equalize All if you 
are completely sure that all the attached streams should have 
the same pressure. While the pressure assignment seems to be 
extraneous, it is of special importance when the Mixer is being 
used to simulate the junction of multiple pipe nodes.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
If you select Equalize All and two or more of the attached 
streams have different pressures, a pressure inconsistency 
message appears. 
In this case, you must either remove the pressure 
specifications for all but one of the attached streams, or 
select Set Outlet to Lowest Inlet. If you specify Set Outlet to 
Lowest Inlet, you can still set the pressures of all the 
streams.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-39
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6-40 Mixer
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Th6.3.3 Rating Tab
You need HYSYS dynamics to specify any rating information for 
the Mixer operation. The Rating tab consists of the Nozzles 
page.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. 
It is strongly recommended that the elevation of the inlet and 
exit nozzles are equal for this unit operation. If you want to 
model static head, the entire piece of equipment can be moved 
by modifying the Base Elevation relative to Ground Elevation 
field.
6.3.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
6.3.5 Dynamics Tab
The Dynamics tab contains the following pages: 
• Specs
• Holdup
• Stripchart
In Dynamic mode, changes in inlet streams to the Mixer are 
seen instantaneously in the outlet stream because the Mixer is 
assumed to have no holdup.
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-40
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ThSpecs Page
The dynamic specifications of the Mixer can be specified on the 
Specs page.
In dynamic mode, there are two possible dynamic specifications 
you can choose to characterize the Mixer operation:
• If you select the Equalize All radio button, the pressure 
of the surrounding streams of the Mixer are equal if static 
head contributions are not considered. This is a realistic 
situation since the inlet stream pressures to a Mixer in an 
actual plant must be the same. With this specification, 
flow to and from the Mixer is determined by the pressure 
flow network. The “one PF specification per flowsheet 
boundary stream” rule applies to the Mixer operation if 
the Equalize All option is chosen. It is strongly 
recommended that you use the Equalize All option in 
order to realistically model flow behaviour in a dynamic 
simulation case.
• If you select the Set Outlet to Lowest Inlet radio 
button, HYSYS sets the pressure of the exit stream of the 
Mixer to the lowest inlet stream pressure. This situation 
is not recommended since two or more streams can 
enter the Mixer at different pressures which is not 
realistic. With this specification, flow to and from the 
Mixer is determined from upstream flow specifications, 
and not from the surrounding pressure network of the 
simulation case. If this option is used, n more pressure-
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab.
 Figure 6.256-41
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6-42 Mixer
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Thflow specifications are required by the PF solver than if 
the Equalize All option is used. The variable, n, is the 
number of inlet streams to the Mixer.
The Product Molar Flow Factor field enables you to scale the flow 
rate coming out of the mixer. For example, there are two parallel 
trains but you only want to model one train. You can accomplish 
modeling one train by changing the Product Molar Flow Factor 
value, so that the flow rate out of the mixer equals the flow rate 
value into the mixer multiplied by the Product Molar Flow Factor 
value.
Holdup Page
Each unit operation in HYSYS has the capacity to store material 
and energy. Typical Mixers in actual plants usually have 
significantly less holdup than other unit operations in a plant. 
Therefore, the volume of the Mixer operation in HYSYS cannot 
be specified and is assumed to be zero. Since there is no holdup 
associated with the Mixer operation, the holdup’s quantity and 
volume are shown as zero in the Holdup page.
The Disable flashes checkbox enables you to turn on and off 
the rigorous flash calculation for the mixer. This feature is useful 
Reverse flow conditions can occur in the Mixer operation if 
the Equalize All radio button is not selected. If flow reverses 
in the Mixer, the Mixer essentially acts like a dynamic Tee 
with the Use Splits as Dynamic Specs checkbox inactive. In 
dynamics, these two unit operations are very similar.
 Figure 6.26
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 6-42
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Thif the PFD has a very large number of mixers, and you do not 
care whether the contents of the streams around them are fully 
up to date or not, or you prefer maximum speed in the 
simulation calculation.
• To turn off the flash calculation, select the Disable 
flashes checkbox.
If the flash calculations are turned off, the outlet stream 
will still update and propagate values, but the phase 
fractions and temperatures may not be correct.
• To turn the flash calculation back on, clear the Disable 
flashes checkbox.
The default selection is to leave the flash calculation on.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
6.4 Pipe Segment
The Pipe Segment is used to simulate a wide variety of piping 
situations ranging from single or multiphase plant piping with 
rigorous heat transfer estimation, to a large capacity looped 
pipeline problems. It offers several pressure drop correlations:
• Aziz, Govier, and Fogarasi
• Baxendell and Thomas
• Beggs and Brill
• Duns and Ros
• Gregory Aziz Mandhane
• Hagedorn and Brown
• HTFS, Liquid Slip
• HTFS, Homogeneous Flow
HYSYS recommend that the flash calculations be left on, as 
in some cases disabled flash calculation can result in 
instabilities or unexpected outcomes, depending on what is 
downstream of the unit operation where the flash has been 
turned off. This feature should only be manipulated by 
advanced users.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.6-43
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6-44 Pipe Segment
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Th• OLGAS2000_2P
• OLGAS2000_3P
• Orkiszewski
• Poettmann and Carpenter
• Tulsa 99
Another option, OLGAS, is also available as a gradient method. 
Four levels of complexity in heat transfer estimation allow you to 
find a solution as rigorous as required while allowing for quick 
generalized solutions to well-known problems.
The Pipe Segment offers four calculation modes. The 
appropriate mode is automatically selected depending on the 
information specified. In order to solve the pipe, you must 
specify enough information to completely define both the 
material balance and energy balance.
Calculation Modes
The Pipe Segment operation contains four calculation modes:
• Pressure Drop
• Length
• Flow
• Diameter
The mode is automatically assigned depending on what 
information is specified.
OLGAS is a third-party option which can be purchased 
through AspenTech or SCANDPOWER.
HYSYS checks for sonic flow if indicated by the option in the 
Calculation page of the Design tab.
Contact your AspenTech 
agent for more 
information, or e-mail 
us at 
info@aspentech.com.6-44
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Piping Operations 6-45
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ThRegardless of which mode you use, you must specify the 
number of increments in the pipe. Calculations are performed in 
each increment; for example, to determine the pressure drop, 
the energy and mass balances calculations are performed in 
each increment, and the outlet pressure in that increment is 
used as the inlet pressure to the next increment. The calculation 
continues down the length of the pipe until the pipe outlet 
pressure is determined.
The Pipe Segment can solve in either direction. The solution 
procedure generally starts at the end where the temperature is 
known (temperature is typically not known on both ends). 
HYSYS then begins stepping through the pipe from that point, 
using either the specified pressure, or estimating a starting 
value. If the starting point is the pipe outlet, HYSYS steps 
backwards through the pipe. At the other end of the pipe, 
HYSYS compares the calculated solution to other known 
information and specifications, and if necessary, restarts the 
procedure with a new set of starting estimates.
Some specifics of each calculation mode are provided in the 
following sections.
Pressure Drop
Assuming that a feed, product, and energy stream are attached 
to the pipe, the following information is required:
• Flow
• Pipe length, diameter, and elevation change
• Heat transfer information
• At least one stream temperature and one pressure
There are two different methods for calculating the pressure 
drop, which are discussed below:6-45
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6-46 Pipe Segment
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ThMethod 1
If you specify the temperature and pressure at the same end of 
the pipe, then energy and mass balances are solved for each 
increment, and the temperature and pressure of the stream at 
the opposite end of the pipe are determined.
Delta P Method 1:
1. At the end where temperature and pressure are specified, 
solve for the outlet temperature and pressure in the first 
segment.
2. Move to the next segment, using the outlet conditions of the 
previous segment as the new inlet conditions.
3. Continue down the pipe until the outlet pressure and 
temperature are solved.
Method 2
If you specify temperature for one stream and pressure for the 
other, an iterative loop is required outside of the normal 
calculation procedure:
• First, a pressure is estimated for the stream which has 
the temperature specified.
• Second, the pressure and temperature for the stream at 
the opposite end of the pipe are determined from 
incremental energy and mass balances as in the first 
method.
• If the calculated pressure and user-specified pressure 
are not the same (within a certain tolerance), a new 
pressure is estimated and the incremental energy and 
mass balances are re-solved. This continues until the 
absolute difference of the calculated and user-specified 
pressures are less than a certain tolerance.
The calculated pressure drop accounts for fittings, frictional, and 
hydrostatic effects.6-46
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Piping Operations 6-47
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ThDelta P Method 2:
1. Estimate a pressure for the stream which has a specified 
temperature.
2. At the end where the pressure is estimated, solve for the 
outlet temperature and pressure in the first segment.
3. Move to the next segment, using the outlet conditions of the 
previous segment as the new inlet conditions.
4. Continue down the pipe until the outlet pressure and 
temperature are solved.
5. If the calculated outlet pressure is not equal to the actual 
pressure, a new estimate is made for pressure (Return to 1).
Length
Assuming that the feed, product, and energy stream are 
attached, the following information is required:
• Flow
• Heat transfer information
• Pipe diameter
• Inlet and Outlet Pressure (or one stream Pressure and 
Pressure Drop)
• One stream temperature
• Initial estimate of Length
For each segment, the Length estimate, along with the known 
stream specifications, are used to solve for the unknown stream 
temperature and pressure. If the calculated pressure is not 
equal to the actual pressure (within the user-specified 
tolerance), a new estimate is made for the length, and 
calculations continue.
A good initial guess and step size decreases the solving time.
The Pipe also solves for the length if you provide one 
pressure, two temperature specifications, and the duty.6-47
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6-48 Pipe Segment
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ThLength Calculation:
1. Estimate a Length. At the end where temperature is 
specified, solve for the outlet temperature and pressure in 
the first segment.
2. Move to the next segment, using the outlet conditions of the 
previous segment as the new inlet conditions.
3. Continue down the pipe until the outlet pressure and 
temperature are solved.
4. If the calculated outlet pressure is not equal to the actual 
pressure, a new estimate is made for length. (Return to 1).
Diameter
Information required in the Diameter calculation mode is the 
same as Length, except HYSYS requires the length instead of 
the diameter of the pipe. Initial estimate of diameter can be 
given on the Calculation page of the Design tab.
Flow
Assuming that a feed, product, and energy stream are attached 
to the pipe, the following information is required:
• Pipe length and diameter
• Heat transfer information
• Inlet and Outlet Pressure (or one stream Pressure and 
Pressure Drop)
• One stream temperature
• Initial estimate of Flow
Using the flow estimate and known stream conditions (at the 
end with the known temperature), HYSYS calculates a pressure 
at the other end. If the calculated pressure is not equal to the 
actual pressure (within the user-specified tolerance), a new 
estimate is made for the flow, and calculations continue. Again, 
a good initial guess decreases the solving time significantly.
Both length and diameter calculations can only be done for 
pipes with a single segment.6-48
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Piping Operations 6-49
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ThFlow Calculation:
1. Estimate Flow. At the end where temperature is specified, 
solve for the outlet temperature and pressure in the first 
segment.
2. Move to the next segment, using the outlet conditions of the 
previous segment as the inlet conditions.
3. Continue down the pipe until the outlet pressure and 
temperature are solved.
4. If the calculated outlet pressure is not equal to the actual 
pressure, a new estimate is made for the flow. (Return to 1).
Incremental Material and Energy Balances
The overall algorithm consists of three nested loops. The outer 
loop iterates on the increments (Pressure, Length or Flow 
Mode), the middle loop solves for the temperature, and the 
inner loop solves for pressure. The middle and inner loops 
implement a secant method to speed convergence. 
The pressure and temperature are calculated as follows:
1. The inlet temperature and pressure are passed to the 
material/energy balance routine.
2. Using internal estimates for temperature and pressure 
gradients, the outlet temperature and pressure are 
calculated.
3. Average fluid properties are calculated based on the inlet 
and estimated outlet conditions.
4. These properties, along with the inlet pressure, are passed 
to the pressure gradient algorithm.
5. With the pressure gradient, the outlet pressure can be 
calculated.
6. The calculated pressure and estimate pressure are 
compared. If their difference exceeds the tolerance (default 
value 0.1 kPa), a new outlet pressure is estimated, and steps 
#3 to #6 are repeated. 
The tolerance is specified in the Calculation page of the 
Design tab.
7. Once the inner pressure loop has converged, the outlet 
temperature is calculated:6-49
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6-50 Pipe Segment
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Th• If U and the ambient temperature are specified, then the 
outlet temperature is determined from the following 
equations:
where:  
Q = amount of heat transferred
U = overall heat transfer coefficient
A = outer heat transfer area
 = log mean temperature difference
Qin = heat flow of inlet stream
Qout = heat flow of outlet stream
• If both the inlet and outlet Pipe temperatures are known, 
the outlet temperature of the increment is calculated by 
linear interpolation. The attached duty stream then 
completes the energy balance.
• If duty is known, the outlet temperature is calculated 
from a Pressure-Enthalpy flash.
When the Increment outlet temperature is calculated, it is 
compared with the estimated outlet temperature. If their 
difference exceeds the tolerance (default value 0.01oC), a 
new outlet temperature is estimated, and new fluid 
properties are calculated (return to step #3). The tolerance 
is specified in the Calculation page of the Design tab.
8. When both the temperature and pressure converge, the 
outlet results are passed to the inlet of the next increment, 
where calculations continue.
(6.20)
(6.21)
Q U A ΔTLM××=
Q Qin Qout–=
ΔTLM6-50
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Piping Operations 6-51
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Th6.4.1 Pipe Segment Property 
View
There are two methods to add a Pipe Segment to the 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select Pipe 
Segment.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Pipe Segment icon.
The Pipe Segment property view appears.
 Figure 6.27
Pipe Segment icon6-51
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6-52 Pipe Segment
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Th6.4.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Calculation
• User Variables
• Notes
Connections Page
On the Connections page, you must specify the feed and 
product material streams.  
In addition to the material stream connections, you also have 
the option of attaching an energy stream to the Pipe Segment 
and selecting the fluid package for the Pipe Segment. You can 
also edit the Pipe Segment name on this page.
In the Inlet, Outlet and Energy drop-down lists either type in 
the name of the stream or if you have pre-defined your 
stream select it from the drop-down list.
 Figure 6.286-52
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Piping Operations 6-53
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ThParameters Page
In the Pipe Flow Correlation group, you can select the 
correlation method used for Two Phase (VL) flow calculations.
The options are:
• Aziz, Govier, and Fogarasi
• Baxendell and Thomas
• Beggs and Brill
• Duns and Ros
• Gregory Aziz Mandhane
• Hagedorn and Brown
• HTFS, Liquid Slip
• HTFS, Homogeneous Flow
• OLGAS2000_2P
• OLGAS2000_3P
• Orkiszewski
• Poettmann and Carpenter
• Tulsa 99
 Figure 6.29
OLGAS is a third-party option that can be purchased through 
AspenTech or SCANDPOWER.6-53
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ThSummary of Methods
The methods above have all been developed for predicting two-
phase pressure drops. Some methods were developed 
exclusively for flow in horizontal pipes, others exclusively for 
flow in vertical pipes while some can be used for either. Some of 
the methods define a flow regime map and can apply specific 
pressure drop correlations according to the type of flow 
predicted. Some of the methods calculate the expected liquid 
holdup in two-phase flow while others assume a homogeneous 
mixture. 
The table below summarizes the characteristics of each model. 
More detailed information on each model is presented later in 
this section.   
For Single Phase streams, the Darcy equation is used for 
pressure drop predictions. This equation is a modified form of 
the mechanical energy equation, which takes into account losses 
due to frictional effects as well as changes in potential energy.
The total heat loss from the Pipe Segment is indicated in the 
Duty field. The total heat loss can be calculated using estimated 
heat transfer coefficients or specified on the Heat Transfer page 
of the Rating tab.
Model Horizontal Flow Vertical Flow Liquid Holdup Flow Map
Aziz, Govier & 
Fogarasi
No Yes Yes Yes
Baxendell & Thomas Use with Care Yes No No
Beggs & Brill Yes Yes Yes Yes
Duns & Ros No Yes Yes Yes
Gregory, Aziz, 
Mandhane
Yes No Yes Yes
Hagedorn & Brown No Yes Yes No
HTFS Homogeneous Yes Yes No No
HTFS Liquid Slip Yes Yes Yes No
Olgas2000 Yes Yes Yes Yes
Orkisewski No Yes Yes Yes
Poettman & 
Carpenter
No Yes No No
Tulsa No Yes Yes Yes6-54
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Piping Operations 6-55
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ThYou can also specify the overall pressure drop for the operation. 
The pressure drop includes the losses due to friction, static 
head, and fittings. If the overall pressure drop is not specified on 
the Parameters page, it is calculated by HYSYS, provided all 
other required parameters are specified.
The Gravitational Energy Change field displays the change in 
potential energy experienced by the fluid across the length of 
the pipe. It is determined for the overall elevation change, 
based on the sum of the elevation change specified for each 
segment on the Sizing page of the Rating tab.
When the pressure drop is specified, the Pipe Segment can be 
used to calculate either the length of the Pipe Segment or the 
flow of the material through the length of pipe.
Notice the calculation type (for example, pressure drop, length, 
flow) is not explicitly specified. HYSYS determines what is to be 
calculated by the information that you provide.
The overall pressure drop, which can be specified or 
calculated by HYSYS, is the sum of the friction, static head, 
and fittings pressure drops. 
When two liquid phases are present, appropriate volume 
based empirical mixing rules are implemented to calculate a 
single pseudo liquid phase. Therefore, caution should be 
exercised in interpreting the calculated pressure drops for 
three-phase systems. 
Actual pressure drops can vary dramatically for different 
flow regimes, and for emulsion systems.6-55
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ThAziz, Govier & Fogarasi
In developing their model2 Aziz, Govier & Fogarasi argue that 
flow regime is independent of phase viscosities and pipe 
diameters but is proportional to the gas density to the one third 
power ( ). From this, then the calculate modified superficial 
gas and liquid velocities on which they base the following flow 
regime map.
Once the flow regime has been determined a range of 
correlations is used to determine the frictional pressure gradient 
and slip velocity or void fraction applicable to that regime.
 Figure 6.30
ρg
1 3⁄6-56
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Piping Operations 6-57
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ThBaxendell & Thomas
The Baxendell & Thomas model3 is an extension of the Poettman 
& Carpenter model to include higher flow rates. It is based on a 
homogeneous model using a two-phase friction factor obtained 
from correlation based on experimental results relating friction 
factor to the parameter . Baxendell & Thomas fitted a 
smooth curve for values of the  parameter greater than 45 
x103 cp. Below this value they propose that original correlation 
of Poettman & Carpenter be used. Baxendell & Thomas claim the 
correlation is suitable for use in calculating horizontal flow 
pressure gradients in addition to the vertical flow pressure 
gradients for which the original Poettman & Carpenter approach 
was developed although the correlation takes no account of the 
very different flow regimes that can occur. Like the Poettman & 
Carpenter model this model assumes that the pressure gradient 
is independent of viscosity.
Beggs and Brill Pressure Gradient
The Beggs and Brill4 method is based on work done with an air-
water mixture at many different conditions, and is applicable for 
inclined flow.
Dρυ
Dρυ6-57
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6-58 Pipe Segment
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ThIn the Beggs and Brill correlation, the flow regime is determined 
using the Froude number and inlet liquid content. The flow map 
used is based on horizontal flow and has four regimes: 
segregated, intermittent, distributed, and transition. The types 
of flow in the first three regime are listed as follows:
• Segregated Flow: Stratified, Wavy, and Annular.
• Intermittent Flow: Plug and Slug.
• Distributed Flow: Bubble and Mist.
Once the flow regime has been determined, the liquid holdup for 
a horizontal pipe is calculated, using the correlation applicable to 
that regime. A factor is applied to this holdup to account for pipe 
inclination. From the holdup, a two-phase friction factor is 
calculated and the pressure gradient determined.
 Figure 6.31
Beggs and Brill Flow Regimes
0.010.0001 0.001 0.1    1
Input Liquid Content
Fr
o
u
d
e 
N
u
m
b
er
    1
   10
   100
1000
Distributed
Segregated
Transition
Intermittent6-58
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Piping Operations 6-59
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ThDuns & Ros
The Duns and Ros model8 is based on a large scale laboratory 
investigation of upward vertical flow of air / hydrocarbon liquid 
and air / water systems. The model identifies three flow regions, 
outlined below.
• Region I. Where the liquid phase is continuous (in other 
words, bubble and plug flow, and part of froth flow 
regimes).
• Region II. Where the phases of liquid and gas alternate 
(in other words, remainder of froth flow regime and slug 
flow regime).
• Region III. Where gas phase is continuous (in other 
words, mist flow and annular flow regime).
The flow region map is shown in the figure below:
 Figure 6.326-59
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ThThe regions are distinguished using functions of four 
dimensionless groups namely a gas velocity number, a liquid 
velocity number, a diameter number, and a liquid viscosity 
number. Separate frictional pressure drop correlations and liquid 
slip velocity (liquid holdup) correlations are defined for each 
region in terms of the same dimensionless groups.
Gregory Aziz Mandhane Pressure Gradient
For the Gregory Aziz Mandhane correlation10, an appropriate 
model is used for predicting the overall pressure drop in two-
phase flow. 
 Figure 6.33
Gregory Aziz Mandhane Flow Regimes
Regime Model
Slugflow Mandhane, et. al. modification #1 of Lockhart-Martinelli
Dispersed Bubble Mandhane, et. al. modification #2 of Lockhart-
Martinelli
Annular Mist Lockhart-Martinelli
Elongated 
Bubble
Mandhane, et. al. modification #1 of Lockhart-Martinelli
 Superficial Gas Velocity (m/sec)
S
u
p
er
fi
ci
a
l 
Li
q
u
id
 V
el
oc
it
y 
(m
/s
ec
) Bubble, 
Elongated 
Bubble Flow
Stratified 
Flow
Dispersed Flow
Slug 
Flow
Wave 
Flow
Annular, 
Annular 
Mist Flow6-60
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ThHagedorn & Brown
Hagedorn & Brown based their model11 on experimental data on 
upward flow of air / water and air / oil mixtures. The frictional 
pressure drop is calculated using a friction factor derived from a 
single phase Moody curve using a two phase Reynolds number 
that reduces to the appropriate single phase Reynolds number 
when the flow becomes single phase. For the void fraction 
required to calculate the two phase Reynolds number and the 
static pressure loss, Hagedorn & Brown developed a single curve 
relating the void fraction to the same dimensionless parameters 
proposed by Duns & Ros.
HTFS Models
The two HTFS models12, 17 share a common method for 
calculating the frictional pressure gradient and acceleration 
pressure gradient while differing in the method used to calculate 
static pressure gradient.
The frictional pressure gradient method is adapted from that of 
Claxton et. al. (1972). The method first calculates the frictional 
pressure drop for the gas and liquid phases assuming that they 
are flowing alone in the pipe based on Fanning friction factors 
for each phase that are again calculated by assuming the fluid is 
flowing alone in the pipe. The frictional pressure drop is then 
calculated from the formula:
where:  
 = frictional pressure drop
 = liquid phase pressure drop
Stratified Lockhart-Martinelli
Wave Lockhart-Martinelli
(6.22)
Regime Model
pF pl Cc pl pgΔΔ( ) pgΔ+ +Δ=Δ
pFΔ
plΔ6-61
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ThCc = correction factor calculated from the properties of the 
liquid and gas phases and the superficial mass 
velocities of the phases
 = gas phase pressure drop
The static pressure gradient is calculated from a separated 
model of two phase flow. In the HTFS Homogeneous model the 
void fraction required by this model is assumed to be the 
homogeneous void fraction. In the HTFS Liquid Slip model the 
void fraction is calculated using a method published by Whalley 
and Ward (1981).
The accelerational gradient term is calculated from a 
homogeneous equation model.
The HTFS models have been validated for horizontal, and both 
upward and downward vertical flow using a wide range of data 
held by the Harwell data bank.
OLGAS2000 (2-Phase & 3-Phase)
OLGAS2000 employs mechanistic models for each of the four 
major flow regimes: stratified, annular, slug, and dispersed 
bubble flow. It is based in large part on data from the SINTEF 
multiphase flow laboratory in Norway.
Multiphase Flow is a dynamic physical process between the 
phases. It includes fluid properties, complex geometry and 
interaction between reservoir, well, flowline and process plant. 
OLGAS 2000 can handle 2-phase and 3-phase flow. For 
instance, the elements involved can consist of water droplets, 
oil, gas, sand, wax, and hydrates.
OLGAS2000 predicts the pressure gradient, liquid holdup, and 
flow regime. It has been tested in one degree increments for all 
angles from horizontal to vertical. OLGAS2000 gives one of the 
best overall predictions of pressure drop and liquid holdup of 
any currently available method.
Contact your AspenTech agent for more information on 
OLGAS2000 and the licensing on OLGAS2000 3-Phase.
pgΔ6-62
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Piping Operations 6-63
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ThOrkisewski
Orkisewski15 composed a composite correlation for vertical 
upward flow based on a combination of methods developed by 
Griffith (1962), Griffith & Wallis(1961), and Duns & Ros (1963)8. 
Four flow regimes are defined and the methods proposed for 
each region are:
• Bubble flow—Griffith correlation
• Slug/Plug flow—Griffith & Wallis correlation modified by 
Orkisewski
• Churn flow—Duns & Ros
• Mist/Annular flow—Duns & Ros
Orkisewski proposed that the method of Griffith and Wallis be 
used to determine the boundary between the bubble and plug 
flow regime and the methods of Duns & Ros be used to 
determine the remaining flow regime boundaries.
Poettman & Carpenter
The Poettman & Carpenter model16 assumes that the 
contribution of the acceleration term to the total pressure loss is 
small and that the frictional pressure drop can be calculated 
using a homogeneous model. The model further assumes that 
the static head loss can be calculated using a homogeneous two 
phase density. Poettman & Carpenter varies from a standard 
homogeneous method in its calculation of a two phase friction 
factor. The model proposes a correlation for the friction factor 
based on experimental results from 49 flowing and gas lift wells 
operating over a wide range of conditions. The two-phase 
friction factor is plotted against the parameter  (D= 
diameter,  = homogeneous density, and  = homogeneous 
superficial velocity). Effectively therefore the model assumes 
that the pressure gradient is independent of viscosity.
Dρυ
ρ υ6-63
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6-64 Pipe Segment
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ThTulsa
The Tulsa model18 proposes a comprehensive mechanistic model 
formulated to predict flow patterns, pressure drop, and liquid 
holdup in vertical upward two-phase flow. The model identifies 
five flow patterns: bubble, dispersed bubble, slug, churn, and 
annular. The flow pattern prediction models used are Ansari et. 
al. (1994) for dispersed bubble and annular flows, Chokshi 
(1994) for bubbly flow and a new model for churn flow. 
The resulting flow pattern map is shown below. 
Separate hydrodynamic models for each flow pattern are used. 
A new hydrodynamic model is proposed for churn flow and a 
modified version of Chokshi’s model is proposed for slug flow. 
Chokshi and Ansari et. al. models are adopted for bubbly and 
annular flows respectively.
The model has been evaluated using the Tulsa University Fluid 
Flow Projects well data back of 2052 wells covering a wide range 
of field data. The model has been compared with Ansari et. al. 
(1994), Chokshi (1994), Hasan & Kabir (1994), Aziz et. al. 
(1972), and Hagedorn and Brown (1964) methods, and is 
 Figure 6.346-64
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Piping Operations 6-65
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Thclaimed to offer superior results.
Calculation Page
You can specify any of the calculation parameters on this page. 
The table below describes the parameters.
All methods account for static head losses, while Aziz, Beggs 
and Brill, and OLGAS methods account for hydrostatic 
recovery. Beggs and Brill calculate the hydrostatic recovery 
as a function of the flow parameters and pipe angle. 
 Figure 6.35
Field Description
Pressure 
Tolerance
Tolerance used to compare pressures in the calculation 
loop.
Temperature 
Tolerance
Tolerance used to compare temperatures in the 
calculation loop.
Heat Flow 
Tolerance
Tolerance used to compare heat flow in the calculation 
loop.
Length Initial 
Guess
Used in the algorithm when length is to be calculated.
Length Step Size Used in the algorithm when length is to be calculated.
Flow Initial 
Guess
Used in the algorithm when flow of material is to be 
calculated.
Flow Step Size Used in the algorithm when flow of material is to be 
calculated
Diameter Initial 
Guess
Optional estimate when diameter is to be calculated.6-65
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Default 
Increments
The increment number which appears for each 
segment on the Dimensions page
Always PH Flash Selecting this checkbox, force HYSYS’ calculations to 
be done using PH flashes rather than PT flashes. 
Slower but more reliable for pure component or narrow 
boiling range systems.
Check Choked 
Flow
When this checkbox is active, HYSYS checks for choked 
flow. The default setting is inactive because the 
command slows down calculations.
This check is carried out only on pipe segments not on 
fitting or swage segments.
Do Deposition 
Calcs
When this checkbox is inactive, HYSYS turns off 
deposition calculations. This checkbox is a duplicate of 
the checkbox on the Deposition tab
Do Slug Tool 
Calculations
When this checkbox is active, HYSYS performs slug 
calculations.
When calculating Flow or Length, good initial guesses and 
step sizes can greatly reduce solution time.
Field Description
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-66
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Th6.4.3 Rating Tab
The Rating tab provides access to the following pages: 
• Sizing
• Heat Transfer
On the Sizing page, you can specify information regarding the 
dimensions of sections in the Pipe Segment. In the Heat Transfer 
page, the heat loss of the Pipe Segment can either be specified 
or calculated from various heat transfer parameters.
Sizing Page
On the Sizing page, the length-elevation profile for the Pipe 
Segment is constructed. You can provide details for each fitting 
or pipe section that is contained in the Pipe Segment that you 
are modeling. An unlimited number of pipe sections or fittings 
can be added on this page.
For a given length of pipe which is modelled in HYSYS, the 
parameters of each segment is entered separately, as they are 
for each fitting.
The procedure for modeling a length of pipe is illustrated using 
the diagram shown below. In the diagram, the pipe length AD is 
represented by segments A, B, C, D, and three fittings.
The table shown below displays the fitting/pipe, length, and 
elevation input that you require to represent the pipe length AD. 
 Figure 6.36
X1
X2 X3
Y1
Y2
F2
A
C
D
B
Example of Pipe Sections and 
Fittings Modelled in the Pipe 
Segment Operation
Fittings
F3
F16-67
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6-68 Pipe Segment
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ThEach pipe section and fitting is labelled as a segment. 
To fully define the pipe section segments, you must also specify 
pipe schedule, diameters (nominal or inner and outer), a 
material, and a number of increments. The fittings require an 
inner diameter value.
Adding Segments
You can add segments to the length-elevation profile by clicking 
the Append Segment button. For each segment that you add, 
you must specify the following: 
Number 1 2 3 4 5 6 7
Represented by A F1 B F2 C F3 D
Fitting/Pipe Pipe Fitting Pipe Fitting Pipe Fitting Pipe
Length x1 N/A y1 N/A x2 N/A
Elevation 0 N/A y1 N/A 0 N/A y2
x3
2 y2
2+
The horizontal pipe sections have an Elevation of 0. A 
positive elevation indicates that the outlet is higher than the 
inlet.
When you have only one pipe segment HYSYS calculates the 
inner diameter of the pipe when a pressure difference and 
pipe length is specified.
Field Description
Pipe/Fitting/
Swage
Select a pipe section, swage or one of the available 
fittings from the drop-down list. If the list does not 
contain the fitting required, you can modify the fittings 
and change its K-factor for these calculations.
You can modify the Fittings Database, which is 
contained in file FITTING.DB. 
Length The actual length of the Pipe Segment. Not required for 
fittings.
Elevation 
Change
The change in vertical distance between the outlet and 
inlet of the pipe section. Positive values indicate that 
the outlet is higher than the inlet. Not required for 
fittings.
Outer Diameter Outside diameter of the pipe or fitting.
Inner Diameter Inside diameter of the pipe or fitting.
For more information, 
refer to Section 7.3.9 - 
Modifying the Fittings 
Database.6-68
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Piping Operations 6-69
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ThOnce you have selected the segment type (pipe, swage, or 
fitting), you can specify detailed information concerning the 
highlighted segment. With the cursor located on a segment, 
click the View Segment button. When you click the View 
Segment button, the Pipe Fittings, Pipe Swages, or Pipe Info 
property view appears. The property view that appears depends 
on the type of Fitting/Pipe option you selected from the drop-
down list.
Material Select one of the available default materials or choose 
User Specified for the pipe section. Not required for 
fittings.
Roughness A default value is provided based on the Pipe Material. 
You can specify this value.
Pipe Wall 
Conductivity
Thermal conductivity of pipe material in W/m.K to allow 
calculation of heat transfer resistance of pipe wall.
Defaults provided for standard pipe materials are as 
follows:
• All steel and coated iron pipes: 45.0
• Cast iron: 48.0
• Concrete: 1.38
• Wood: 0.173
• PlasticTubing: 0.17
• RubberHose: 0.151
Increments The number of increments the pipe section is divided 
for calculation purposes.
The pipe segment report has been updated to include 
dedicated detail sections for both fittings and swage fittings. 
These sections appear in the parameters datablock.
Field Description6-69
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6-70 Pipe Segment
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ThViewing Segments
The Pipe Info property view appears for pipe sections. On this 
property view, the following information is shown:.
 Figure 6.37
Field Description
Pipe 
Schedule
Select one of the following:
• Actual. The nominal diameter cannot be specified. 
The inner diameter can be specified.
• Schedule 40 
• Schedule 80 
• Schedule 160 
HYSYS contains a pipe database for three pipe schedules 
(40, 80, 160). If a schedule is specified, a popup menu 
appears indicating the possible nominal pipe diameters that 
can be specified.
Nominal 
Diameter
Provides the nominal diameter for the pipe section.
Inner 
Diameter
For Schedule 40, 80, or 160, this is referenced from the 
database. For Actual Pipe Schedule, this can be specified 
directly by the user.
Pipe Material Select a pipe material or choose User Specified. The pipe 
material type can be selected from the drop-down list in the 
field. A table of pipe materials and corresponding Absolute 
Roughness factors is shown in the next table.
The roughness factor is automatically specified for pipe 
material chosen from this list. You can also specify the 
roughness factor manually.6-70
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Piping Operations 6-71
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ThFitting Pressure Loss
The fittings pressure loss is characterised by a two constant 
equation as shown below.
where:  
A = constant, also known as velocity head factor
B = constant, also known as FT factor
fT = fully turbulent friction factor
Roughness A default value is provided based on the Pipe Material. You 
can specify a value if you want.
Pipe Wall 
Conductivity
Thermal conductivity of pipe material in W/m.K to allow 
calculation of heat transfer resistance of pipe wall.
Defaults provided for standard pipe materials are as 
follows:
• All steel and coated iron pipes: 45.0
• Cast iron: 48.0
• Concrete: 1.38
• Wood: 0.173
• PlasticTubing: 0.17
• RubberHose: 0.151
Pipe Material Type Absolute Roughness, m
Drawn Tube 0.0000015
Mild Steel 0.0000457
Asphalted Iron 0.0001220
Galvanized Iron 0.0001520
Cast Iron 0.0002590
Smooth Concrete 0.0003050
Rough Concrete 0.0030500
Smooth Steel 0.0009140
Rough Steel 0.0091400
Smooth Wood Stave 0.0001830
Rough Wood Stave 0.0009140
(6.23)
Field Description
K A B fT×+=6-71
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6-72 Pipe Segment
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ThNote that when defining the pressure drop characteristics for a 
fitting, either A or B are specified, but not both.
The fittings pressure loss constant K is then used to obtain the 
pressure drop across the fitting from the equation shown below.
where:  
 = pressure drop
 = density
 = velocity
Calculation of the fully turbulent friction factor (fT) needed in the 
method requires knowledge of the relative roughness of the 
fitting. This is calculated from user entered values for roughness 
and fitting diameter. The Pipe Segment’s standard friction factor 
equation (Churchill) is then called repeatedly with the calculated 
relative roughness at increasing Reynolds numbers until the 
limiting value of friction factor is found.
The pressure drop is usually described as “head loss” 
represented by
where  is commonly referred to as the “velocity head.” 
Looking at this equation, you will note some similarity with the 
pressure drop equation 6.24. Since  represents the 
pressure drop associated with the height of a liquid column with 
a known density, 
(6.24)
(6.25)
(6.26)
ΔP Kρν
2
2
--------=
PΔ
ρ
ν
hL K v2
2
----⎝ ⎠
⎛ ⎞×=
v2
2
----
ρ g hL××
ΔP ρ g hL×× ρ K v2
2
----×× ρ K velocity head××= = =6-72
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ThFor this reason, HYSYS calls K in this expression the “VH factor” 
or “velocity head factor.” It is also commonly called a K-factor or 
piping K-factor.
In the original expression , K is sometimes defined 
as 
where:  = equivilent length of the fitting in pipe diameters 
In general a fitting is characterised by either a velocity head 
factor (A) or a FT factor (B) but not both. HYSYS does not 
enforce this restriction however and you are free to define both 
factors for a fitting if required.
Pipe Fittings Property View
You can customize the pipe in the Pipe Fitting property view.
The above property view shows a standard fitting as it would be 
retrieved from the fittings database. If you customize a fitting 
by changing either the VH Factor or FT Factor, the word User is 
added to the fitting name to denote the fact that it is now user 
defined, and the Data Source field becomes modifiable to allow 
you to describe the source of the new data.
(6.27)
 Figure 6.38
K A B fT×+=
K ft
Leq
D
---------×=
Leq
D
---------
Refer to Section 7.3.9 - 
Modifying the Fittings 
Database for more 
information.6-73
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6-74 Pipe Segment
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ThDefault data for FT Factor and Data Source is provided for cases 
retrieved from earlier versions of HYSYS. Specifically the FT 
Factor is set to 0.0 and the Data Source is set to “HYSYS, pre 
V2.3”. The VH Factor is the same as the K Factor used in earlier 
versions.
Swage Fittings
A new capability has been added to the Pipe Segment to allow 
the pressure drop across reductions or enlargements in the pipe 
line to be calculated. The feature has been added as a new 
fitting type called a swage. The swage fitting automatically uses 
the upstream and downstream pipe/fitting diameters to 
calculate the K factor for the fitting. Once the K factor is known 
the pressure loss across the reducer/enlarger can be calculated. 
The equations used are as follows.
where:  
 = static pressure loss
 = density
 = velocity
K = reducer/enlarger K factor
(6.28)ΔP Kout
ρoutνout
2
2
----------------------
ρinνin
2
2
-----------------–
ρoutνout
2
2
----------------------+=
ΔP
ρ
ν
6-74
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ThThe K factor from the above equation is calculated from the 
following equations: 
 in the equations above is known as swage angle. Swage angle 
is shown in the figure below:
Equations for K above are taken from Crane, Flow of Fluids, 
Publication 410M, Appendix A-26.
For reducers
where:
(6.29)
For enlargers
where:
(6.30)
 Figure 6.39
Kout 0.8 θ
2
-- 1 β2–( ) for θ 45°≤( )
Kout 0.5 1 β2–( ) θ
2
--sin for 45( ° θ 180° )≤<=
sin=
β
dout
din
---------=
Kout
2.6 θ
2
-- 1 β2–( )
2
sin
β4
----------------------------------------- for θ 45°≤( )
Kout
1 β2–( )
2
β4
--------------------- for 45° θ 180°≤<( )=
=
β
din
dout
---------=
θ
6-75
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ThAs stated above a swage segment automatically considers the 
upstream (din) and downstream (dout) diameters to work out 
whether the swage is a reducer or an enlarger and calculate the 
appropriate K value. In addition the following special cases are 
detected and a fixed K value is used.
• The swage is the first segment in the pipe and an 
entrance K value of 0.5 is used.
• The swage is the last segment in the pipe and an exit K 
value of 1.0 is used.
• din = dout the swage is a simple coupling and a K value of 
0.04 is used.
Pipe Swages Property View
A new swage fitting property view has been created to allow you 
to update the swage angle for a swage fitting. It also displays 
the upstream and downstream diameters that are used in the 
calculation as shown in the figure below.
The automatic detection of upstream and downstream 
diameters by the swage segment means that there cannot be 
two consecutive swage segments in a pipe. This restriction is 
enforced by HYSYS which prevents you from specifying two 
adjacent segments to be swages. In addition, if two adjacent 
swage segments would result from deletion of an intervening 
pipe or fitting segment, the second swage segment is 
automatically converted to a default Pipe Segment. An 
explanatory message appears in both cases.
 Figure 6.406-76
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ThRemoving a Segment
To remove a segment from the Length-Elevation Profile group, 
select one of its parameters and click the Delete Segment 
button.
You can remove all input from the Length-Elevation Profile group 
by clicking the Clear Profile button.
Heat Transfer Page
The Heat Transfer page is used to enter data for defining the 
heat transfer. The Specify By group, at the top of the property 
view, contains four radio buttons. Selecting one of the radio 
buttons displays one of the four ways of defining heat transfer:
• Specified heat loss
• Overall Heat Transfer Coefficient (HTC)
• HTC specified by segment
• Estimated HTC
No confirmation is given by HYSYS before segments are 
removed.
The radio button does not force the pipe segment to use that 
method of calculation – it only provides access to the 
property views.
HYSYS works out which method to use from the data 
provided.6-77
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ThHeat Loss
HYSYS selects the Heat Loss radio button as the default setting, 
when you select the Heat Transfer page for the first time. The 
property view appears as shown in the figure below:
If the Overall heat duty of the pipe is known, the energy balance 
can be calculated immediately. Each increment is assumed to 
have the same heat loss. You enter the heat loss for the pipe in 
the Heat Loss field. This assumption is valid when the 
temperature profile is flat, indicating low heat transfer rates 
compared to the heat flows of the streams. This is the fastest 
solution method. 
If both inlet and outlet temperatures are specified, a linear 
profile is assumed and HYSYS can calculate the overall heat 
duty. This method allows fast calculation when stream 
conditions are known. Select the Heat Loss radio button to see 
the calculated overall heat duty. 
 Figure 6.41
The value in the Heat Loss field is black in colour, signifying 
that the value was generated by HYSYS.6-78
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ThOverall HTC
When you select the Overall HTC radio button, the Heat Transfer 
page changes to the property view shown in the figure below.
If the overall HTC and a representative ambient temperature are 
known, rigorous heat transfer calculations are performed on 
each increment.
Segment HTC
When you select the Segment HTC radio button, the Heat 
Transfer page changes to the property view shown in the figure 
below.
 Figure 6.42
Overall HTC is the overall heat transfer coefficient based 
upon the outside diameter of the pipe
 Figure 6.436-79
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6-80 Pipe Segment
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ThIf the heat transfer coefficient and a representative ambient 
temperature are known for each segment. You can specify the 
ambient temperature and HTC for each pipe segment that was 
created on the Sizing page. HYSYS performs rigorous heat 
transfer calculations on each increment.
Estimate HTC
When you select the Estimate HTC radio button, the Heat 
Transfer page changes to the property view shown in the figure 
below. 
If the pipe’s HTC is unknown, you can enter information in this 
property view and HYSYS calculates the HTC for the pipe.
Segment HTC is based upon the outside diameter of the pipe.
 Figure 6.44
The Overall HTC and Estimate HTC can be used together to 
define the heat transfer information for the pipe.
If you only know the Ambient Temperature, you can supply it 
in the Overall HTC section and have the Overall HTC value 
calculated by the Estimate HTC section. Likewise, you need 
to specify the Ambient Temperature in the Estimate HTC 
section for the pipe segment to have enough heat transfer 
information to solve.
You can select 
whether the 
ambient 
temperature used 
in the heat 
transfer 
calculations is for 
the entire pipe or 
for each segment 
of the pipe.6-80
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Piping Operations 6-81
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ThInside Film Convection
You can prompt HYSYS to estimate the inside film heat transfer 
coefficient using one of the five correlations provided.
The Petukov, Dittus, and Sieder methods for calculation of inner 
HTC are limited to single phase applications and essentially 
turbulent flow only. Two and three phase systems are modeled 
using the single phase equations with “averaged” fluid 
properties. A correction for laminar flow is applied but this is not 
particularly effective. It is recommended that these three 
methods be used only for single phase pipelines operating at 
high Reynolds numbers (> 10000). 
The Profes and HTFS methods should provide much better 
results for two and three phase systems, and in the laminar flow 
region at the cost of some increase in calculation time. In 
general the Profes option is recommended for most pipeline 
applications since it takes into full account the flow regime in the 
pipe and is reasonably efficient in calculation. The HTFS option is 
more calculation intensive, particularly in two phase applications 
where additional flash calculations are required. It is 
recommended for use in cases with a high heat flux with high 
delta temperatures between the pipe contents and ambient 
conditions.
The five correlations provided are:
• Petukov (1970)
(6.31)h k
d
--
f 8⁄( )RedPr
1.07 12.7 f 8⁄( )1 2⁄ Pr2 3⁄ 1–( )+
-----------------------------------------------------------------------------=6-81
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Th• Dittus and Boelter (1930)
• Sieder and Tate (1936)
• Profes. Implements the methods used by the Profes 
Pipe Simulation program (formerly PLAC). The methods 
are based on the Profes flow maps for horizontal and 
vertical flow, and appropriate correlations are used to 
determine the HTC in each region of the flow map.
• HTFS. Implements the methods used by HTFS programs. 
Separate correlations are used for boiling and condensing 
heat transfer, and for horizontal and vertical flow. The 
methods used are documented in the HTFS Handbook13.
where:
n = 
(6.32)
For two-phase flow:
(6.33)
For single phase flow:
where: (6.34)
h k
d
--0.023Red
0.8Prn=
0.4 for heating→
0.3 for cooling→
h2-phase
k
d
--0.027Red
0.8Pr1 3⁄
μb
μw
------⎝ ⎠
⎛ ⎞
0.14
=
h1-phase hlam( )12 h2-phase( )12+[ ]
1
12
-----
=
hlam 3.66 0.0668d
L
-- R× e Pr
1 0.04 d
L
-- RePr⎝ ⎠
⎛ ⎞
2
3
--
+
---------------------------------------------×+=
Refer to the ProFES 
Reference Guide for 
more information.6-82
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ThYou can choose to include the pipe’s thermal resistance in your 
HTC calculations by selecting the Include Pipe Wall checkbox. 
Activating this option requires that the thermal conductivity be 
defined for the pipe material on the detail property view of each 
Pipe Segment. Default values of thermal conductivity are 
provided for the standard materials that can be selected in the 
Pipe Segment.
Outside Conduction/Convection
Outside convection to either Air, Water, or Ground can be 
included by selecting the Include Outer HTC checkbox. For air 
and water, the velocity of the ambient medium is defaulted to 1 
m/s and is user-modifiable. The outside convection heat transfer 
coefficient correlation is for flow past horizontal tubes (J.P. 
Holman, 1989):
If Ground is selected as the ambient medium, the Ground type 
can then be selected. The thermal conductivity of this medium 
appears but is also modifiable by typing over the default value.
The Ground types and their corresponding conductivities are 
tabulated below:     
(6.35)
Ground Type Conductivity Ground Type Conductivity
Dry Peat 0.17 W/mK Frozen Clay 2.50 W/mK
Wet Peat 0.54 W/mK Gravel 1.10 W/mK
Icy Peat 1.89 W/mK Sandy Gravel 2.50 W/mK
Dry Sand 0.50 W/mK Limestone 1.30 W/mK
Moist Sand 0.95 W/mK Sandy Stone 1.95 W/mK
Wet Sand 2.20 W/mK Ice 2.20 W/mK
Dry Clay 0.48 W/mK Cold Ice 2.66 W/mK
Moist Clay 0.75 W/mK Loose Snow 0.15 W/mK
Wet Clay 1.40 W/mK Hard Snow 0.80 W/mK
h k
d
--0.25Re0.6Pr0.38=6-83
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6-84 Pipe Segment
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ThIn HYSYS, the surrounding heat transfer coefficient value is 
based on the following heat transfer resistance equation:
where:  
Hsurroundings = surrounding heat transfer coefficient
Rsurroundings = surrounding heat transfer resistance
Zb = depth of cover to centreline of pipe
ks = thermal conductivity of pipe-surrounding material (Air, 
Water, Ground)
Dot = outer diameter of pipe, including insulation
Conduction Through Insulation
Conduction through the insulation or any other pipe coating can 
also be specified. Several representative materials are provided, 
with their respective thermal conductivities. You must specify a 
thickness for this coating.  
(6.36)
(6.37)
Insulation / Pipe Conductivity Insulation / Pipe Conductivity
Evacuated 
Annulus
0.005 W/mK Asphalt 0.700 W/mK
Urethane Foam 0.018 W/mK Concrete 1.000 W/mK
Glass Block 0.080 W/mK Concrete 
Insulated
0.500 W/mK
Fiberglass Block 0.035 W/mK Neoprene 0.250 W/mK
Fiber Blanket 0.070 W/mK PVC Foam 0.040 W/mK
Fiber Blanket-Vap 
Barr
0.030 W/mK PVC Block 0.150 W/mK
Plastic Block 0.036 W/mK PolyStyrene 
Foam
0.027 W/mK
Hsurroundings
1
Rsurroundings
--------------------------------=
Rsurroundings
Dot
2ks
-------
2Zb 4Zb
2 Dot
2–+
Dot
-------------------------------------------ln=6-84
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Piping Operations 6-85
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Th6.4.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation.
6.4.5 Performance Tab
The Performance tab consists of the following pages:
• Profiles
• Slug Options
• Slug Results 
Profiles Page
The Profiles page allows you to access information about the 
fluid stream conditions for each specified increment in the Pipe 
Segment.
The PF Specs page is relevant to dynamics cases only.
 Figure 6.45
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-85
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6-86 Pipe Segment
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ThThe page contains a summary table for the segments which 
make up the Pipe Segment. The distance (length), elevation, 
and number of increments appear for each segment. You cannot 
modify the values on this page.
To view the Pipe Profile property view, click the View Profile 
button. This view consists of a Table tab and a Plot tab. 
The Table tab displays the following information for each 
increment along the Pipe Segment:
• Length
• Elevation
• Pressure
• Temperature
• Vapour Fraction
• Heat Transferred
• Flow Regime
• Liquid Holdup
• Friction Gradient
• Static Gradient
• Accel Gradient
• Liquid Reynolds Number
• Vapour Reynolds Number
• Liquid Velocity
• Vapour Velocity
• Deposit Thickness
• Deposit Volume
The Plot tab graphically displays the profile data that is listed on 
the Table page. Select one of the radio buttons to view a profile 
with Length as the x-axis variable.
You can modify the plot by right-clicking on the plot area, and 
selecting Graph Control from the object inspect menu.
Refer to Section 1.3.1 - 
Graph Control Property 
View for information 
regarding the 
customization of plots.6-86
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ThSlug Tool
The Slug Tool predicts slug properties for horizontal and inclined 
two-phase flows in each Pipe Segment. Travelling wave solutions 
of the one-dimensional averaged mass and momentum 
equations are found and analysed to obtain slug flow properties. 
Stratified flow is tested for instability to small disturbances and 
then analysed in the unstable region to find if slug flow is 
possible. If large amplitude waves can bridge the pipe then slug 
flow is deemed to be possible. In this slug flow region a range of 
frequencies is possible with a maximum slug frequency 
occurring for slugs of zero length. Up to this maximum there is a 
relationship between frequency and slug length with maximum 
lengths occurring for the lowest frequencies. The other slug 
properties such as bubble length, average film holdup, slug 
transitional velocity, average pressure gradient can all be found 
over the range of allowable slug frequencies.
The detailed methodology used to predict slug formation and 
slug properties was developed within AspenTech and is 
described in the paper “The modelling of slug flow properties” by 
M Watson19.
Slug Options Page
 Figure 6.466-87
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6-88 Pipe Segment
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ThThe entries on the Slug Options page control the models and 
parameters used by the slug tool in its calculations as follows:
• Translational Model. You can select the option to be 
used for calculating the translational velocity of the slugs 
in the pipeline. The general form of the translational 
velocity is of the form:
You have the option to select the Bendikson (1984) 
model to predict values of C0 and U0 or to select User 
Specified to enter values manually.
• Holdup Model. You can select the option to be used to 
calculate the liquid holdup in the pipe. Two options are 
available: Gregory et. al. uses the methods published by 
Gregory et. al. (1978) or User Specified to enter a user 
defined value for the holdup fraction.
• Friction Factor. Two options are available to select the 
friction factor model to be used in the slug tool 
calculations: Smooth pipe or Colebrook equation.
• Frequency Option. The slug tool evaluates slug flow 
characteristics at a particular slug frequency. This 
frequency can either be predicted by the Hill & Wood 
correlation or specified by the user.
where:
c = translation velocity of slug
VM = superficial velocity of two phase mixture
C0, U0 = constants
(6.38)
c C0VM U0+=6-88
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ThSlug Results Page
The Slug Results page presents the result from the slug tool 
analysis as a table with the following entries.
 Figure 6.47
Column Description
Position Distance along the pipe.
Status Result of the slug calculations. Possible results are 
Single Phase, Stable two phase, Slug flow, Annular 
flow, Bubble flow or Unknown. Any error in the 
calculation is also reported here.
Frequency Slug frequency used to calculate the slug properties. 
This is normally the value calculated by the Hill & Wood 
correlation or the user specified slug frequency 
according to the settings on the Slug Options page. 
When the correlation or user specified frequency lies 
outside the predicted range of slug frequencies this 
field shows either the minimum or maximum slug 
frequency which is indicated by the entry in the next 
column.
Slug Length Average length of a slug at the indicated frequency.
Bubble Length Average length of a bubble at the indicated frequency.
Film Holdup Film holdup as a fraction.
Velocity Translational velocity of the slug.
Pressure 
Gradient
Pressure drop over the slug/bubble unit.
Slug/Bubble 
ratio
Ratio of lengths of slug and bubble.6-89
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6-90 Pipe Segment
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ThCell Details
When you click the View Cell Plot button on the Slug Results 
page, the Cell Details property view appears. 
The property view shows the slug properties for a single position 
in the pipe across the full range of possible slug frequencies in 
both tabular and graphical form. A further graph shows the flow 
regime map for the cell indicating the region of possible slug 
formation at different vapour and liquid flowrates.
The Next button and Previous button on the property view allow 
you to move along the pipe to inspect the detailed results at any 
point. 
6.4.6 Dynamics Tab
The Dynamics tab contains basic pipe parameter options to 
configure the pipe for Dynamics mode.
 Figure 6.48
Pipe unit operation does not model choking or advanced 
effects such as shock waves, momentum balances, and so 
on.
To model choking and other advanced effects, use ProFES, 
OLGA pipe extensions, or Aspen Hydraulics flowsheet.6-90
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ThParameters Page
The Parameters page allows you to specify the pipe flow model, 
holdup type, and base elevation for the Dynamics mode.
The following table lists and describes the objects available in 
the Parameters page:
 Figure 6.49
Object Description
Simple Pipe 
Friction Model 
Method radio 
button
Allows you to select between turbulent and full range 
Churchill methods to simulate the pipe flow model in 
Dynamics mode.
The Pipe Friction Model drop-down list is only 
available if you select the Simple Pipe Friction Model 
Method radio button.
Pipe Model 
Correlations 
radio button
Allows you to select the pipe flow model based on the 
available pipe flow correlation selection from the 
Parameters Page in the Design tab.
The calculation time for this method is long and 
rigorous, however, the results are more accurate.
one holdup in 
pipe radio button
Allows you to calculate the overall holdup values of the 
entire pipe.
This method calculates the results by lumping together 
all the volume. The calculation time is short, however, 
this method is not recommended if you want to track 
composition (or model lag) along the pipe.
one holdup per 
segment radio 
button
Allows you to calculate the holdup values for each 
segment in the entire pipe.
This method calculates and models the composition 
and other changes through the pipe network 
rigorously. The calculation time is long, however, the 
results are more accurate.
Refer to Friction Factor 
section for more 
information.6-91
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ThHoldup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
For each phase contained within the volume space of the unit 
operation, the following is specified:
Model Holdup 
Volume 
checkbox
Allows you to calculate pipe volumes based on the pipe 
lengths and diameter. 
Generally the pipe volumes are ignored or lumped 
together in one vessel for the calculation, unless a 
model of the composition lag is required. 
The lumped volume approach is a simpler more robust 
option, and often the pressure drop result is the main 
interest. Having to consider many holdups with small 
volumes may lead to instabilities.
Base Elevation of 
Inlet Relative to 
Ground field
Allows you to specify the elevation of the pipe relative 
to the ground for Dynamics mode.
 Figure 6.50
Holdup Details Description
Holdup No. Displays the designated number of each segment in 
the pipe. Number 1 indicates the first segment, 
number 2 indicates the second segment, and so forth.
Accumulation The accumulation refers to the rate of change of 
material in the holdup for each phase.
Moles The amount of material in the holdup for each phase.
Volume The holdup volume of each phase.
Object Description6-92
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ThStripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
6.4.7 Deposition Tab
Deposition is a general capability that can be used to model 
deposition of material that affects pressure drop or heat transfer 
to or from the pipe. Possible deposits include wax, asphaltenes, 
hydrates, sand, and so forth. The Deposition tab contains the 
following pages:
• Methods
• Properties
• Profile
• Limits
HYSYS provides a model for one type of deposit namely Wax 
deposition modeled using the Profes methods. Other third party 
methods can be added as plug-in extensions.
Methods Page
The Methods page displays the available deposition methods. 
Profes Wax is the only standard one at present. 
 Figure 6.51
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
For more information 
about the Profes Wax 
method, refer to Section 
7.3.8 - Profes Wax 
Method.6-93
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ThRegistered third party plug-in methods also appear on this page.
The Profes Wax model is installed by selecting it from the 
Deposition Correlation list. On installation the Pipe Segment is 
not able to solve until the initial deposition thickness is defined 
on the Profile page. Once the initial deposition thickness is 
defined the model solves using the default values provided for 
the other deposition data properties.
The Max. Time field allows you to specify the maximum amount 
of time wax deposits on the pipe. The Timestep field allows you 
to specify the timestep that the deposition rate is integrated 
over.
Properties Page
The Properties page allows you to specify deposit properties 
required by the deposition calculations.
The page consists of three properties:
• Density of the deposit.
• Thermal Conductivity of the deposit.
• Yield Strength of the deposit.
When solving with its default data, the model displays a 
warning message in the status bar of the Pipe Segment.
 Figure 6.526-94
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ThProfile Page
The Profile page consists of the Deposition Profile table.
This table has two purposes:
• Is used to specify the initial deposition thickness, 
required by the deposition calculations.
• Displays the profile of the deposit on the pipe.
Limits Page
 Figure 6.53
 Figure 6.546-95
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6-96 Pipe Segment
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ThThe Limits page allows you to specify the maximum limits for 
the following parameters.
• Max. Deposit Thickness
• Overall Pressure Drop
• Total Deposit Volume
• Plug Pressure Drop
• Simulation Time
6.4.8 Profes Wax Method
The deposition of the wax from the bulk oil onto the pipe wall is 
assumed to only be due to mass transfer; shear dispersion is 
not considered to be a significant factor. The rate of deposition is 
described by:
where:  
m’ = deposition rate (kg/s)
k = mass transfer coefficient (mole/m2 s mole Fraction)
C = local concentration of wax forming components (mole 
fraction)
Mwwax = molecular weight of wax (kg/mole)
A = cross-sectional area (m2)
The mass transfer coefficient is calculated using the following 
correlation:
where:  
Sc = 
(6.39)
(6.40)
m' k Cwall Cbulk–( )AMwwax=
Sh 0.015 Re0.88× Sc
1
3
--
=
μl
ρlD
--------6-96
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ThRe = 
Sh = 
D = diffusivity of wax in oil (m2/s)
 = liquid viscosity (kg/ms)
 = liquid density (kg/m2)
k = mass transfer coefficient (mole/m2 s mole fraction)
DH = hydraulic radius (m)
Vl = liquid velocity (m/s)
c = liquid molar density (mole/m3)
The Reynolds number that is used in these calculations is based 
on the local liquid velocity and liquid hydraulic radius. Physical 
properties are taken as the single phase liquid values. The 
viscosity used is based on the fluid temperature and shear rate 
at the wall.
The difference in concentration of wax forming species between 
the bulk fluid and the wall, which is the driving force for the 
deposition of wax is obtained from calculating the equilibrium 
wax quantities at the two relevant temperatures.
These calculations provide a wax deposition rate which is 
integrated over each timestep to give the total quantity of wax 
laid down on the pipe wall.
VlρlDH
μl
-----------------
kDH
cD
----------
μ
ρl6-97
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ThProfes Wax Property View
When you click the View Method button, the Profes Wax 
property view appears. You can change the default data in the 
Profes Wax model, and tune it to your specific application in this 
property view. The Profes Wax property view consists of three 
tabs:
• Wax Data
• Tuning Data
• Ref. Comp
The Calculate wax formation temperature checkbox allows 
you to select whether the deposition model is to calculate the 
initial wax formation temperature or cloud point for each pipe 
element when performing the deposition calculations. If 
activated the results appear in the Profile page of the 
Deposition tab. 
The Tune button initiates the tuning calculations and is only 
active when there is sufficient data to allow tuning calculation to 
take place. In other words, cloud point is defined, at least one 
temperature or wax mass percent pair is defined and reference 
composition defined.
Wax Data Tab
The Wax Data tab allows you to select the wax model to be used 6-98
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Thfor the wax equilibrium calculations.
The Wax Model drop-down list provides you with four 
thermodynamic models for wax formation:
• Chung
• Pederson
• Conoco
• AEA (default)
 Figure 6.556-99
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ThAll models are based on the following equation for the 
equilibrium constant, Ki, which is the ratio of concentrations of a 
particular component in the solid and liquid phase:
where:  
xi = mol fraction
 = activity coefficient
f = standard state fugacity
P = pressure
V = molar volume
T = temperature
R = gas constant
S, L = denote solid and liquid phases
Once the equilibrium constant for each component has been 
calculated, they are used to determine the quantities and 
composition of each phase. The differences between the various 
thermodynamic models depend on how the terms in the 
equilibrium constant equation are evaluated. The four models 
available in the Profes method are described by the following 
equations:
• AEA:
(6.41)
(6.42)
Ki
xi
S
xi
L
----
ζi
Lfi
L
ζi
Sfi
S
---------
Vi
L Vi
S–
RT
------------------
0
P
∫⎝ ⎠
⎜ ⎟
⎛ ⎞
P∂exp= =
ζi
Kiln
hi
fΔ
RT
------- 1 T
Ti
f
----–
⎝ ⎠
⎜ ⎟
⎛ ⎞ CpΔ
R
--------- 1
Ti
f
T
----–
Ti
f
T
----ln+
Vi
L Vi–
RT
----------------- P∂
0
P
∫+ +=6-100
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Th• Chung:
• Conoco (Erikson):
• Pederson:
where:  
 = enthalpy of melting
Ti 
f = melting temperature
V = molar volume
T = temperature
R = gas constant
 = solubility parameter
 = heat capacity difference between solid and liquid
m = denotes mixture properties
i = component
(6.43)
(6.44)
(6.45)
Kiln
hi
fΔ
RT
------- 1 T
Ti
f
----–
⎝ ⎠
⎜ ⎟
⎛ ⎞ Vi
L
RT
------ δm
L δi
L–( )
2 Vi
L
Vm
------ 1
Vi
L
Vm
------–+ln+ +=
Kiln
hi
fΔ
RT
------- 1 T
Ti
f
----–
⎝ ⎠
⎜ ⎟
⎛ ⎞
=
Kiln
Vi
L δm
L δi
L–( )
2
Vi
S δm
S δi
S–( )
2
-------------------------------
hi
fΔ
RT
-------+ 1 T
Ti
f
----–
⎝ ⎠
⎜ ⎟
⎛ ⎞ CpΔ
R
--------- 1
Ti
f
T
----–
Ti
f
T
----ln++=
Δhi
f
δ
ΔCp6-101
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ThAll the models require a detailed compositional analysis of the 
fluid in order to be used effectively. For the Conoco model, 
Erickson et al proposed that the hydrocarbon analysis should 
distinguish between normal and non-normal paraffin 
components, as there is a substantial difference in melting 
points between these two groups. The melting temperatures 
make a  significant impact on the predicted cloud point for any 
given composition. In Pederson model, the Ki values depend on 
the composition of the liquid and solid phases, unlike normal 
equilibrium calculations where the Ki s are fixed for any 
temperature and pressure and can lead to unstable or incorrect 
numerical solutions.
The AEA model is the only model which incorporates a term for 
the effect of pressure on the liquid-solid equilibrium. The result  
is to counteract the increased solubility of wax forming 
components at high pressures which is due to more light ends 
entering the liquid phase. Using this model, the predicted cloud 
point and wax quantities can both increase or decrease with 
increasing pressure, depending on the fluid composition.
The table allows you to select which components in the system 
are able to form wax. The default criteria for the components in 
this table are as follows:
• Components with a mole weight less than 140 or 
inorganic component types can never form wax. The 
checkbox for these components is set to a grey checkbox 
that cannot be modified.
• Hydrocarbon component types form wax. The checkbox 
is automatically selected for these components, but you 
can clear the checkbox. Hypothetical components 
generally fall into this category.
• Other organic component types do not form wax. The 
checkbox is clear but you can select it.
The ability to select whether a particular component forms wax 
gives you additional control when defining the wax formation 
characteristics of a system. For example, you can define two 
hypothetical components with common properties, and by 
setting one as a wax former you could vary the quantity of wax 
produced in the boiling range covered by the hypotheticals by 
varying their proportions.6-102
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ThTuning Data Tab
The Tuning Data tab allows you to define the observed wax 
formation characteristics of a system to tune the wax model.
The Cloud Point Input field allows you to specify the temperature 
at which the first wax appears. In other words, the phase 
transition temperature between single liquid phase and the two 
phase wax/liquid mixture.
The table of Temperature vs. Wax Mass Percent allows you to 
define the quantity of wax deposit observed as a function of 
temperature. New points can be added to the table in any order; 
they are sorted by temperature when the tuning process is run. 
To run the tuning calculations a minimum of one pair of data 
points is required. Up to 10 pairs of data points can be specified.
 Figure 6.56
To remove a point from the table both the temperature and 
the wax mass percent values must be deleted.
Calculated values 
for the Cloud Point 
and Wax Mass 
Percent appear in 
the calculated field 
and column after 
the tuning process 
is run.6-103
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ThRef Comp Tab
The Ref Comp tab allows you to specify the reference 
composition of the fluid that is used for tuning calculations.
Tuning Process
The tuning process is a series of calculations that is initiated as a 
task by clicking the Tune button. The first step validates the 
tuning data specified as follows:
• that there is at least one component identified as a wax 
former.
• a valid reference composition has been entered.
• sorting the pairs of temperature/wax mass percent in 
order of descending temperature.
• ensure cloud point temperature is greater than any 
temperature in table of temperature/wax mass percent 
pairs.
If any problem is found the tuning process stops, and an 
appropriate error message appears on the tuning status bar.
If the tuning data is valid then the tuning process first does a 
VLE flash at 15°C and 100 kPa to calculate the liquid 
composition of the reference stream. This is used as the base 
 Figure 6.57
The Normalise 
button allows 
you to 
normalise the 
composition 
entered and 
setting any 
unspecified 
fractions to 
zero.
The composition 
is entered in a 
table as either a 
mole or mass 
fraction 
depending on 
which radio 
button is 
selected.6-104
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Thcomposition for all subsequent tuning calculations. If a liquid 
phase cannot be found in the reference stream at these 
conditions the tuning calculations fail.
The tuning process then continues using an iterative least 
squares solution method. Progress of the tuning process is 
output to the main HYSYS status bar. When complete the tuning 
process checks for convergence and displays the result on the 
tuning status bar. If the tuning process converged then the 
calculated results on the Tuning data tab are updated. If the 
tuning process failed to converge the tuning parameters are set 
to the best values that were obtained. Tuning parameters can be 
reset to their original values by re-selecting the wax model.
There are three tuning parameters available for the Chung, 
Pederson, and Conoco wax models, and four tuning parameters 
for the AEA model. The tuning process only attempts to tune as 
many parameters as is possible from the specified data (for 
example, cloud point + one pair of temperature/wax percent 
data allows tuning of two parameters, more pairs of 
temperature/wax percent data points are required to tune 
additional parameters). In cases where an attempt to tune three 
or four parameters fails to converge, a second tuning attempt is 
made automatically for just two tuning parameters.
The convergence of the tuning process is checked by looking at 
the cloud point result since this is the most critical parameter. 
Generally convergence is achieved when there are one or two 
pairs of temperature/wax percent data. Given the emphasis 
placed on achieving the cloud point the calculated results for 
wax percent can often show greater errors, particularly when 
there are multiple temperature/wax percent points. 
You should realise that the degree to which the tuning 
parameters can adjust the temperature/wax percent curve 
predicted by the models is limited, and that hand tuning by 
changing the number and proportion of wax forming 
components in the system may be required in some cases.6-105
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Th6.4.9 Modifying the Fittings 
Database
The fittings data base contains VH Factor and FT Factor data 
taken from Perry. Some of the Factor data are taken from Crane.
The following table details the values in the database. The Data 
Source column displays the source of the data values.
Description
VH 
Factor
FT 
Factor
Swage 
Angle
Data Source
Pipe 0 0 0
Swage: Abrupt 0 0 180
Swage: 45 degree 0 0 45
Elbow: 45 Std 0 16 0 Crane 410M, A-29
Elbow: 45 Long 0.2 0 0 Perry 5th ed, Table 5-19
Elbow: 90 Std 0 30 0 Crane 410M, A-29
Elbow: 90 Long 0.45 0 0 Perry 5th ed, Table 5-19
Bend: 90, r/d 1 0 20 0 Crane 410M, A-29
Bend: 90, r/d 1.5 0 14 0 Crane 410M, A-29
Bend: 90, r/d 2 0 12 0 Crane 410M, A-29
Bend: 90, r/d 3 0 12 0 Crane 410M, A-29
Bend: 90, r/d 4 0 14 0 Crane 410M, A-29
Bend: 90, r/d 6 0 17 0 Crane 410M, A-29
Bend: 90, r/d 8 0 24 0 Crane 410M, A-29
Bend: 90, r/d 10 0 30 0 Crane 410M, A-29
Bend: 90, r/d 12 0 34 0 Crane 410M, A-29
Bend: 90, r/d 14 0 38 0 Crane 410M, A-29
Bend: 90, r/d 16 0 42 0 Crane 410M, A-29
Bend: 90, r/d 20 0 50 0 Crane 410M, A-29
Elbow: 45 Mitre 0 60 0 Crane 410M, A-29
Elbow: 90 Mitre 0 60 0 Crane 410M, A-29
180 Degree Close Return 0 50 0 Crane 410M, A-29
Tee: Branch Blanked 0 20 0 Crane 410M, A-29
Tee: As Elbow 0 60 0 Crane 410M, A-29
Coupling/Union 0.04 0 0 Perry 5th ed, Table 5-19
Gate Valve: Open 0.17 0 0 Perry 5th ed, Table 5-19
Gate Valve: Three Quarter 0.9 0 0 Perry 5th ed, Table 5-19
Gate Valve: Half 4.5 0 0 Perry 5th ed, Table 5-19
Gate Valve: One Quarter 24 0 0 Perry 5th ed, Table 5-196-106
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ThGate Valve, Crane: Open 0 8 0 Crane 410M, A-27
Diaphram Valve: Open 2.3 0 Perry 5th ed, Table 5-19
Diaphram Valve: Three 
Quarter
2.6 0 0 Perry 5th ed, Table 5-19
Diaphram Valve: Half 4.3 0 0 Perry 5th ed, Table 5-19
Diaphram Valve: One 
Quarter
21 0 0 Perry 5th ed, Table 5-19
Globe Valve: Open 6 0 0 Perry 5th ed, Table 5-19
Globe Valve: Half 9.5 0 0 Perry 5th ed, Table 5-19
Globe Valve, Crane: Open 0 340 0 Crane 410M, A-27
Angle Valve: Open 2 0 0 Perry 5th ed, Table 5-19
Angle Valve, 45 deg: Open 0 55 0 Perry 5th ed, Table 5-19
Angle Valve, 90 deg: Open 0 150 0 Crane 410M, A-27
Blowoff Valve: Open 3 0 0 Perry 5th ed, Table 5-19
Plug Cock: Angle 5 0.05 0 0 Perry 5th ed, Table 5-19
Plug Cock: Angle 10 0.29 0 0 Perry 5th ed, Table 5-19
Plug Cock: Angle 20 1.56 0 0 Perry 5th ed, Table 5-19
Plug Cock: Angle 40 17.3 0 0 Perry 5th ed, Table 5-19
Plug Cock: Angle 60 206 0 0 Perry 5th ed, Table 5-19
Plug Cock: Open 0 18 0 Crane 410M, A-29
Butterfly Valve: Angle 5 0.24 0 0 Perry 5th ed, Table 5-19
Butterfly Valve: Angle 10 0.52 0 0 Perry 5th ed, Table 5-19
Butterfly Valve: Angle 20 1.54 0 0 Perry 5th ed, Table 5-19
Butterfly Valve: Angle 40 10.8 0 0 Perry 5th ed, Table 5-19
Butterfly Valve: Angle 60 118 0 0 Perry 5th ed, Table 5-19
Butterfly Valve: 2-8in, Open 0 45 0 Crane 410M, A-28
Butterfly Valve: 10-14in, 
Open
0 35 0 Crane 410M, A-28
Butterfly Valve: 16-24in, 
Open
0 25 0 Crane 410M, A-28
Ball Valve: Open 0 3 0 Crane 410M, A-28
Check Valve: Swing 2 0 0 Perry 5th ed, Table 5-19
Check Valve: Disk 10 0 0 Perry 5th ed, Table 5-19
Check Valve: Ball 70 0 0 Perry 5th ed, Table 5-19
Check Valve: Lift 0 600 0 Crane 410M, A-27
Check Valve: 45 deg Lift 0 55 0 Crane 410M, A-27
Foot Valve 15 0 0 Perry 5th ed, Table 5-19
Foot Valve: Poppet disk 0 420 0 Crane 410M, A-28
Foot Valve: Hinged disk 0 75 0 Crane 410M, A-28
Water Meter: Disk 7 0 0 Perry 5th ed, Table 5-19
Description
VH 
Factor
FT 
Factor
Swage 
Angle
Data Source6-107
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ThA few sections from the “fittings.db” file are shown below:
This can be broken down, line by line:
1. FittingType elbow45std
What this does is define an object “elbow45std” of type 
“FittingType”. “FittingType” has three members 
(parameters): a VH Factor (K-Factor), FT factor or Swage 
angle, and a description. 
2. VHFactor 0.0
This is the K-Factor for the fitting. When you add a fitting to 
the fittings list, this is the number that is put in the K-Factor 
column.
3. Desc “Elbow: 45 Std”
Water Meter: Piston 15 0 0 Perry 5th ed, Table 5-19
Water Meter: Rotary 10 0 0 Perry 5th ed, Table 5-19
Water Meter: Turbine 6 0 0 Perry 5th ed, Table 5-19
User Defined 0 0 0 User specified
Description
VH 
Factor
FT 
Factor
Swage 
Angle
Data Source
FittingType elbow45std
   VHFactor 0.0
   Desc “Elbow: 45 Std”
   FTFactor 16.0
   Data Source “Crane 410M, A-29”
end
FittingType swage2
   VHFactor 0.0
   Desc “Wage: 45 degree”
   Sweating 45.0
end
...
FittingTypeGroup FTG
    AddFitt elbow45std
...
end
The object name “elbow45std” is only an internal name; it 
doesn't appear in any lists or property views.6-108
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ThThis assigns a label (description) to the fitting “elbow45std”. 
It is this label that is used in the fittings window to select 
fittings.
4. This line contains one of the following two possible command 
lines:
• FTFactor 16.0
This is the FT factor for the fitting. When you add a fitting 
to the fittings list, this is the number that is put in the FT 
factor column.
• Swage Angle 45
This command is used to assign the value for the swage 
angle fitting calculation method.
5. DataSource “Crane 410M, A-29”
This tells you where the data source was taken from.
6. end
This tells HYSYS that the description of “elbow45std” is 
done.
So, you have a definition of a fitting. But, that's not quite 
enough. All the fittings are gathered into one group - a 
“FittingTypeGroup”- to make it easier for HYSYS to determine 
what should go where.
1. FittingTypeGroup FTG
Same as line 1 above. This defines an object “FTG” of type 
“FittingTypeGroup”. “FTG” can have many parameters, but 
they must all be of the same type - FittingType. The 
FittingTypeGroup is like a container for all the pipe fittings.
2. AddFitt elbow45std
This adds the previously defined fitting to the group. Notice 
that the fitting MUST be defined before it is added to the 
group. All new fittings should be added last in the database 
file. When the fittings appear in the drop-down list, they are 
sorted alphabetically by their Desc parameter.
3. end
This tells HYSYS that you have added all the fittings you 
want to the fitting group. Notice that HYSYS does not 
automatically put fittings in the group just because they are 
defined beforehand. 6-109
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ThFor example, if we had defined “elbow45std” as above, but 
forgot to add it to the fittings group, there would be no way 
to access it in the fittings window.
Also, the “end” command is very important. If you forget to 
put an “end” in somewhere in the middle of the fittings.db 
file, you can get errors that may or may not tell you what is 
actually wrong.
Adding a Fitting
So, now you can add your own fitting. Open the “fitting.db” file 
in an ASCII editor and move somewhere in the middle of the file 
(but make sure that you are above the definition of the fittings 
group).
Now, add the following lines:
FittingType loopdeloop
VHFactor 10.0
Desc “Loop-de-loop!”
FT Factor 0.0
DataSource “Add fitting demo”
end
You have now created a fitting. You don't have to indent the 
VHFactor, Desc, FTFactor, and DataSource lines, it just makes 
for neater and easier to read files. Next, the fitting needs to be 
added to the fittings group.
Find the line in the file that says “FittingTypeGroup FTG”. Now, 
go anywhere between this line and the “end” line and type the 
following:
AddFitt loopdeloop
Now all you have to do is run HYSYS and make a Pipe Segment. 
The new fitting “Loop-de-loop!” appears in the fittings drop-
down list, and if you add a “Loop-de-loop!” to the fittings list, it 
comes up with a K-Factor of 10.0.
New fittings should be added as the last entry in the 
database.6-110
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ThTo take out the fitting, just delete the lines that were previously 
added.
6.5 Relief Valve
The Relief Valve unit operation can be used to model several 
types of spring loaded Relief Valves. Relief Valves are used quite 
frequently in many different industries in order to prevent 
dangerous situations occurring from pressure buildups in a 
system. Its purpose is to avert situations that occur in a 
dynamic environment. The flow through the Relief Valve can be 
vapour, liquid, liquid with precipitate, or any combination of the 
three.
6.5.1 Relief Valve Property 
View
There are two ways that you can add a Relief Valve to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select Relief 
Valve.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing the F4.
2. Double-click the Relief Valve icon. 
Relief Valve icon6-111
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ThThe Relief Valve property view appears.
6.5.2 Design Tab
The Design tab of the Relief Valve property view contains the 
following pages: 
• Connections
• Parameters
• User Variables
• Notes
 Figure 6.586-112
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ThConnections Page
The Connections page is where the inlet and outlet streams of 
the Relief Valve are specified.
The page contains the following fields described in the table 
below: 
 Figure 6.59
Field Description
Name The name of the Relief Valve. HYSYS provides a default 
designation for the unit operation, however, you can edit this 
name at any time by entering a new name in this field.
Inlet Stream entering Relief Valve. You can either select a pre-
existing stream from the drop-down list associated with this 
field or you can create a new stream by selecting this field and 
typing the stream name.
Outlet Relief Valve exit stream. Like the Inlet field, you can either 
select a pre-existing stream from the drop-down list associated 
with this field or you can create a new stream by selecting this 
field and typing the stream name.
Fluid 
Package
Displays the fluid package associated to the relief valve. If the 
simulation case contains multiple fluid packages, you can open 
the drop-down list and select a different fluid package.6-113
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ThParameters Page
The Parameters page contains only two fields, which are 
described in the table below: 
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Object Description
Set Pressure The pressure that the Relief Valve begins to open.
Full Open Pressure The pressure that the Relief Valve is fully open.
 Figure 6.60
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-114
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Th6.5.3 Rating tab
The Rating tab contains the following pages:
• Sizing 
• Nozzles
Sizing Page
On the Sizing page, you can specify the Valve Type, and the 
Capacity Correction Factors and Parameters.
Valve Type
In HYSYS, you can specify three different valve characteristics 
for any Relief Valve in the simulation case.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Rating tab.
 Figure 6.61
Valve Type Description
Quick Opening A Relief Valve with quick opening valve characteristics 
obtains larger flows initially at lower valve openings. As 
the valve opens further, the flow increases at a smaller 
rate.6-115
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ThCapacity Correction Factors and Parameters
The Capacity Correction Factors and Parameters group consists 
of five parameters of the flow equations. You can set:
• Viscosity Coefficient (KV)
• Discharge Coefficient (KD)
• Back Pressure Coefficient (KB)
• Valve Head Differential Coefficient
• Orifice Area (A)
For more information on the function of these parameters, 
consult the following section on flow through the Relief Valve.
Flow Through Relief Valve
The mass flowrate through the Relief Valve varies depending on 
the vapour fraction and the pressure ratio across the valve. For 
two phase flow, the flows are proportional to the vapour fraction 
and can be calculated separately and then combined for the 
total flow. 
Vapour Flow In Valve
For gases and vapours, flow may be choked or non-choked. If 
the pressure ratio is greater than the critical, the flow is NOT 
Linear A Relief Valve with linear valve characteristics has a flow, 
which is directly proportional to the valve % opening.
Equal 
Percentage
A Relief Valve with equal percentage valve characteristics 
initially obtains very small flows at lower valve openings. 
However, the flow increases rapidly as the valve opens to 
its full position.
In the following calculation for the Relief Valve, HYSYS uses 
the rigorous value for k.
Valve Type Description6-116
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Thchoked:
where:  
P1 = upstream pressure
P2 = downstream pressure
K = ratio of Specific Heats
For Choked vapour flow, the mass flowrate is given by the 
following relationship:
where:  
W = mass flow rate
A = relief valve orifice area
KL = capacity correction factor for valve lift
KD = coefficient of discharge
KB = back pressure coefficient
V1 = specific volume of the upstream fluid
P1 = upstream pressure
K = ratio of Specific Heats
For non-Choked vapour flow, the mass flowrate is given by:
(6.46)
(6.47)
(6.48)
P2
P1
----- 2
K 1+
------------
K
K 1–
------------
≥
W AKLKDKB
P1K
V1
--------- 2
K 1+
------------
K 1+
K 1–
------------
1
2
--
=
W AKLKD
P1
V1
----- 2K
K 1–
------------⎝ ⎠
⎛ ⎞ P2
P1
-----⎝ ⎠
⎛ ⎞
2
K
---
P2
P1
-----⎝ ⎠
⎛ ⎞
K 1+
K
------------
–  
⎝ ⎠
⎜ ⎟
⎜ ⎟
⎛ ⎞
1
2
--
=
6-117
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ThLiquid Flow In Valve
Liquid Flow through the valve is calculated using the following 
equation:
where:  
W = mass flow rate
A = relief valve orifice area
KL = capacity correction factor for valve lift
KD = coefficient of discharge
KV = viscosity correction factor
P1 = upstream pressure
P2 = downstream pressure
K = ratio of Specific Heats
 = density of upstream fluid
Capacity Correction Factor (KL)
The Capacity Correction Factor for back pressure is typically 
linear with increasing back pressure. The correct value of the 
factor should be user-specified. It may be obtained from the 
valve manufacturer. The capacity correction factor for valve lift 
compensates for the conditions when the Relief Valve is not 
completely open. 
(6.49)W AKLKDKV 2 P1 P2–( )ρ1[ ]
1
2
--
=
ρ16-118
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ThIncreasing-sensitivity valves have the following flow 
characteristics:
Linear and decreasing-sensitivity valves have the following flow 
characteristics:
where:  
The valve head differential term allows for customization of the 
flow characteristics with respect to stem travel. Its value can 
range between 0 and 1.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. 
(6.50)
(6.51)
(6.52)
KL
L2
a 1 a–( )L4+[ ]
1 2⁄
--------------------------------------------=
KL
L
a 1 a–( )L2+[ ]
1 2⁄
--------------------------------------------=
a valve head differential a maximum flow
valve head differential at zero flow
----------------------------------------------------------------------------------------------=
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.6-119
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Th6.5.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
6.5.5 Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• Advanced
• Stripchart
Specs Page
The PF Specs page is relevant to dynamics cases only.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab.
 Figure 6.62
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-120
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ThThe Specs page consists of two groups:
• Dynamic Parameters
This group consists of three parameters.
Parameter Descriptions
Delta P Pressure drop across the valve.
Valve Lift The Relief Valve lift. It is calculated using one of the 
two following formulas:
If inlet pressure is increasing:
(6.53)
where: 
P1 = upstream pressure
POPEN = set pressure
PFULL = full open pressure
If inlet pressure is decreasing:
(6.54)
where: 
P1 = upstream pressure
PRESEAT = reseating pressure
PCLOSE = closing pressure
Percentage Open The Valve Lift in percentage.
L
P1 POPEN–
PFULL POPEN–
--------------------------------------=
L
P1 PRESEAT–
PCLOSE POPEN–
------------------------------------------=6-121
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Th• Hysteresis Parameters 
When the Enable Valve Hysteresis checkbox is 
selected, the Hysteresis Parameters group appears. This 
group contains two fields, which are described in the 
table below:
Holdup Page
The Holdup page contains information regarding the holdup 
properties, composition, and amount.
Advanced Page
The fail-safe function in Relief Valve is used to prevent pipeline 
and equipment from physical damages due to escalation in 
pressure. The plant operator can either apply this feature to 
relief the pressure built-up from affecting other parts of the 
plant or it can be used in their training to simulate valve 
stickiness or failure.
Field Descriptions
Closing 
Pressure
Pressure that the valve begins to close after reaching the 
full lift pressure. In other words, the value entered in the 
full pressure field on the Parameters page of the Design 
tab.
Reseating 
Pressure
The pressure that the valve reseats after discharge.
Each unit operation in HYSYS has the capacity to store 
material and energy. Typical Valves usually have 
significantly less holdup than other unit operations in a 
plant. Therefore, the volume of the Valve operation in HYSYS 
is defaulted to be zero.
For more information, 
refer to the valve 
operation Holdup Page 
in the Dynamics tab.6-122
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ThThe Relief Valve has five fail modes. The way that these fail 
modes interact with the relief valve is somewhat different from 
the ones of the control valve discussed in Chapter 1.6.3 - Control 
Valve Actuator of the HYSYS Dynamic Modeling guide.
To activate the relief valve fail mode option, ensure that the 
Integrator is running with HYSYS Dynamics license. 
To set the Relief Valve in fail state, you can select the Valve has 
Failed checkbox on the Advanced page. You can now specify 
one of the following fail modes:
• None. Relief valve operates as it is designed to be (same 
as the operating condition when the Valve has Failed 
checkbox is not active).
• Fail Open. The valve lift completely opens. The valve lift 
remains at maximum opening position even when the 
inlet pressure is not longer above the opening (set) 
pressure. The Relief Valve continues to fully open until it 
is reset.
• Fail Shut. The valve lift completely closes. The valve life 
stays shut even when the inlet pressure is above the 
opening (set) pressure. The Relief Valve remains fully 
shut until it is reset.
• Fail Hold. Allows you to simulate the valve lift stickiness 
by holding the valve lift to the last failed position. The 
Relief Valve lift will not move even when the inlet 
pressure is no longer above the opening pressure.
• Fail Specified. Allows you to manually specify the fail 
position when the Relief Valve has failed. The fail position 
is expressed in terms of percentage of the valve opening, 
and it is used to define the amount of valve lift.
 Figure 6.63
Refer to Chapter 1.6 - 
HYSYS Dynamics in the 
HYSYS Dynamic 
Modeling guide for more 
information. 6-123
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6-124 Tee
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ThStripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
6.6 Tee
The Tee operation splits one feed stream into multiple product 
streams with the same conditions and composition as the feed 
stream, and is used for simulating pipe tees and manifolds.
The dynamic Tee operation functions very similarly to the steady 
state Tee operation. However, the enhanced holdup model and 
the concept of nozzle efficiencies can be applied to the dynamic 
Tee. Flow reversal is also possible in the Tee depending on the 
pressure-flow conditions of the surrounding unit operations.
6.6.1 Tee Property View
There are two ways that you can add a Tee to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property views property view 
appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select Tee.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Tee icon.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.
Tee icon6-124
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ThThe Tee property view appears.
6.6.2 Design Tab
The Design tab contains the following pages: 
• Connections
• Parameters
• User Variables
• Notes
Connections Page
On the Connections page, you can specify the feed stream, any 
number of product streams (all of which are automatically 
assigned the conditions and composition of the feed stream), 
and the fluid package associated to the Tee operation.
 Figure 6.646-125
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6-126 Tee
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ThThe only difference among the product streams is the flow rate, 
determined by the flow ratios, which you specify on the 
Parameters page (Steady State mode) or the outlet valve 
openings, which you specify on the Dynamics page (Dynamic 
mode).
Parameters Page
For steady state calculations, specify the desired flow ratio (the 
ratio of the outlet stream flow to the total inlet flow). You can 
toggle between ignoring or acknowledging when a negative flow 
occurs by selecting the Warn on Negative Flow checkbox.
 Figure 6.65
 Figure 6.666-126
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ThA flow ratio is generally between 0 and 1; however, a ratio 
greater than one can be given. In that case, at least one of the 
outlet streams have a negative flow ratio and a negative flow 
(backflow). 
For N outlet streams attached to the Tee, you must specify N-1 
flow ratios. HYSYS then calculates the unknown stream flow 
ratio and the outlet flow rates.
where:  
ri = flow ratio of the ith stream
fi = outlet flow of the ith stream
F = feed flow rate
N = number of outlet streams
 Figure 6.67
(6.55)
(6.56)
With the Warn on Negative 
Flow checkbox selected, the 
status bar is yellow when 
negative flow occurs.
With the Warn on Negative 
Flow checkbox clear, the 
status bar is green when 
negative flow occurs.
ri
1 i=
N
∑ 1.0=
ri
fi
F
---=6-127
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6-128 Tee
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ThFor example, if you have four outlet streams attached to the 
Tee, you must give three flow ratios and HYSYS calculates the 
fourth. 
If you switch to Dynamic mode, the flow ratio values do not 
change if the values are between 0 and 1 (they are equal to the 
dynamic flow fractions).
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
 Figure 6.68
   F
   1
   3
   2
. . . . .
   N
 f1
 f2
 f3
 fN
• Inlet flow F
• N outlet streams
• Specify N-1 flow ratios ri
• Outlet stream flows f1 = r1F
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-128
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Th6.6.3 Rating tab
You need HYSYS dynamics to specify any rating information for 
the Tee operation.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
It is strongly recommended that the elevation of the inlet and 
exit nozzles are equal for this unit operation. If you want to 
model static head, the entire piece of equipment can be moved 
by modifying the Base Elevation relative to the Ground Elevation 
field.
6.6.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
6.6.5 Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• Stripchart
The PF Specs page is relevant to dynamics cases only.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamic tab.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-129
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6-130 Tee
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ThSpecs Page
The dynamic specifications of the Tee can be specified on the 
Specs page: 
If the Use Splits as Dynamic Flow Specs checkbox is 
selected, the exit flows streams from the Tee are user-defined. 
You can define the molar flow for each exit stream by specifying 
the specific valve openings for each exit stream from the Tee. 
This situation is not recommended since the flow from the Tee is 
determined from split fractions and not from the surrounding 
pressure network of the simulation case. If this option is used, 
the valve opening fields should be specified all Tee exit streams. 
In addition a single pressure and single flow specification are 
required by the PF solver.
 Figure 6.69
In Dynamic mode, there are two specifications you can 
choose to characterize the Tee operation.6-130
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ThIf the Use Splits as Dynamic Flow Specs checkbox is inactive, 
the flow rates of the exit streams are determined from the 
pressure network. If this option is set, the dynamic Tee acts 
similar to a Mixer set with the Equalize All option. The “one PF 
specification per flowsheet boundary stream” rule applies to the 
Tee operation if the Use Splits checkbox is inactive. It is strongly 
recommended that you clear the Use Splits checkbox in order 
to realistically model flow behaviour in your dynamic simulation 
case.
Reverse flow conditions can occur in the Tee operation if the Use 
Splits checkbox is inactive. If flow reverses in the Tee, it acts 
essentially like a dynamic Mixer with the Equalize All option. In 
dynamics, these two unit operations are very similar.
Holdup Page
Each unit operation in HYSYS has the capacity to store material 
and energy. Typical Tees in actual plants usually have 
significantly less holdup than other unit operations in a plant. 
Therefore, the volume of the Tee operation in HYSYS cannot be 
specified and is assumed to be zero. Since there is no holdup 
associated with the Tee operation, the holdup’s quantity and 
volume are shown as zero in the Holdup page.
 Figure 6.70
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 6-131
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6-132 Tee
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ThThe Disable flashes checkbox enables you to turn on and off 
the rigorous flash calculation for the tee. This feature is useful if 
the PFD has a very large number of tees, and you do not care 
whether the contents of the streams around them are fully up to 
date or not, or you prefer maximum speed in the simulation 
calculation.
• To turn off the flash calculation, select the Disable 
flashes checkbox.
If the flash calculations are turned off, the outlet stream 
will still update and propagate values, but the phase 
fractions and temperatures may not be correct.
• To turn the flash calculation back on, clear the Disable 
flashes checkbox.
The default selection is to leave the flash calculation on.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
HYSYS recommend that the flash calculations be left on, as 
in some cases disabled flash calculation can result in 
instabilities or unexpected outcomes, depending on what is 
downstream of the unit operation where the flash has been 
turned off. This feature should only be manipulated by 
advanced users.
Refer to Section 1.3.7 
- Stripchart Page/Tab 
for more information.6-132
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Th6.7 Valve
HYSYS performs a material and energy balance on the inlet and 
exit streams of the Valve operation. HYSYS performs a flash 
calculation based on equal material and enthalpy between the 
two streams. It is assumed that the Valve operation is 
isenthalpic. 
The following is a list of variables that can be specified by the 
user in the Valve operation. 
• Inlet temperature
• Inlet pressure
• Outlet temperature
• Outlet pressure
• Valve Pressure Drop
A total of three specifications are required before the Valve 
operation solves. At least one temperature specification and one 
pressure specification are required. HYSYS calculates the other 
two unknowns.
There are also a number of new features that are available with 
the Valve operation. The Valve is a basic building block in HYSYS 
dynamic cases. The new Valve operation models control valves 
much more realistically. The direction of flow through a Valve is 
dependent on the pressures of the surrounding unit operations. 
Like the steady state Valve, the dynamics Valve operation is 
isenthalpic.
Some of the new features in the Valve operation include:
• A pressure-flow specification option that realistically 
models flow through the valve according to the pressure 
network of the plant. Possible flow reversal situations can 
therefore be modeled.
• A pipe segment contribution that can model pressure 
losses caused by an attached pipe’s roughness and 
diameter.
• A new valve equation that incorporates static head and 
frictional losses from the valve and/or pipe segment.
• A model incorporating Valve dynamics such as the 
stickiness in the valve and dynamic behaviour in the 
actuator.6-133
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6-134 Valve
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Th• Different valve types such as linear, equal percentage, 
and quick opening valves.
• Built-in sizing features that determine valve parameters 
used in the valve equation.
The total valve pressure drop refers to the total pressure 
difference between the inlet stream pressure and the exit 
stream pressure. The total pressure drop across the Valve is 
calculated from the frictional pressure loss of the Valve, and the 
pressure loss from static head contributions.
6.7.1 Valve Property View
There are two ways that you can add a Valve to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Piping Equipment radio button.
3. From the list of available unit operations, select Valve.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Valve icon. 
Valve icon6-134
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ThThe Valve property view appears.
6.7.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 6.716-135
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6-136 Valve
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ThConnections Page
The Connections page allows you to specify the name of the 
operation, as well as the inlet stream and outlet stream.
Parameters Page
The pressure drop of the Valve operation can be specified on the 
Parameters page.
 Figure 6.72
 Figure 6.736-136
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
6.7.3 Rating Tab
The Rating tab contains the following pages:
• Sizing
• Nozzles
• Options
Sizing (dynamics) Page
The Sizing (dynamics) page contains the following elements:
• Valve Manufacturer group
• Valve Type group
• Sizing Conditions group
• Valve Operating Characteristics group
• Sizing Methods group
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Rating tab. 
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.6-137
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6-138 Valve
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Th• Size Valve button
Valve Manufacturer Group
The Valve Manufacturers group contains a drop-down list that 
allows you to select the valve manufacturer type/equation 
model. The figure on the left, displays all the manufacturers 
available in HYSYS.
• Masoneilan
• Mokveld
• Fisher. This equation model is based on the test program 
results from Fisher Controls International, Inc. 
(developed the equation in 1963). This model accurately 
predicts the flow for either high or low recovery valves, 
for any gas and under any service conditions.
• Introl
• Valtek
• CCI Drag
• Universal Gas Sizing. This equation model is very similar 
to the Fisher equation. The difference between the two is 
the backwards compatibility when the valve has both 
vapour and liquid flowing through. The Universal Gas 
Sizing model uses the overall density for the vapour. 
Future versions of HYSYS will allow you to select the 
density model.
 Figure 6.746-138
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Th• Simple resistance equation. This equation model treats 
the flow as always being proportional to the square root 
of the pressure drop. No choking is modelled. This 
equation is often used when a simple model is desired, or 
if you want to calculate and update the equation 
constant.
Valve Type Group
Some of the valve manufacturers also provide different types of 
valves for you to choose from. This group is only available if the 
selected valve manufacturer provides multiple valve types.
The following table lists the currently supported valve 
manufacturers and their associated valve type:
Valve 
Manufacturer
Valve Type
Masoneilan • DP Globe: V-Port
• SP Globe: flow to 
open
• Control Ball
• Globe: contoured
• Split Body: flow to 
open
• Split Body: flow to 
close
• 40000,41000 Series
• Camflex: flow to close
• Camflex: flow to open
• Butterfly (Minitork)
• Gobe: flow to close
Mokveld • RZD-R
• RZD-RES
• RZD-RVX
• RZD-REVX
• RZD-RCX
Introl • Series 60A
• Series 60
• Series 10 HF
• Series 20 H
• Series 10 HFD
• Series 20 HFD
• Series 10 flow to open
• Series 20 flow to open
• Series 10 flow to close
• Series 10 HFT
• Series 20 HFT
Valtek • Vector One 60 deg
• Vector One 90 deg
• Dragon Tooth
• Mark One flow to open
• Mark Two flow to open
• Mark One flow to close
• Mark Two flow to close
Valve Type group6-139
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6-140 Valve
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ThSizing Conditions Group
HYSYS uses the stream conditions provided in the Sizing 
Conditions group to calculate valve parameters, which are used 
in the valve equation.
This group contains two radio buttons and a table.
• Current radio button. Allows you to view and modify the 
current variable values for the valve sizing conditions. 
The current variable values are calculated based on the 
stream flow rate and HYSYS default values provided in 
the table.
• User Input radio button. Allows you to view and modify 
the variable values for the valve sizing conditions. The 
variable values are calculated based on the values you 
provide in the table.
The table contains the following cells:
Cell Description
Inlet Pressure Displays the inlet pressure of the fluid flowing through 
the valve. This value cannot be modified.
Molecular 
Weight
Displays the molecular weight of the fluid flowing 
through the valve. This value cannot be modified.
Valve Opening Allows you to modify the percentage opening of the 
valve.
Delta P Allows you to specify the pressure difference in the 
valve.
Flow Rate Allows you to modify the mass flow rate of the fluid 
flowing through the valve. You can only modify the 
mass flow rate, if you select the User Input radio 
button.6-140
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ThValve Operating Characteristics Group
The Valve Operating Characteristics group contains four radio 
buttons.
To select the method to characterize the valve:
1. In the Valve Operating Characteristics group, select the 
method you want to use by clicking the appropriate radio 
button: Linear, Quick Opening, Equal Percentage, and 
User Table.
If you select Linear, Quick Opening, or Equal Percentage:
2. In the Sizing Methods group, select Cv or Cg radio button 
and specify the parameter values in the appropriate cells.
If you select User Table:
3. In the Valve Operating Characteristics group, click the View 
button. The valve Characteristics Curve property view 
appears.
4. In the Lift (% of max) column, specify the percentage of 
the valve opening. This percentage value is based on the 
maximum valve opening.
5. In the Flow (% of max) column, specify the flow rate 
percentage. This percentage value is based on the maximum 
fluid flow rate through the valve.
Object Description
Linear radio 
button
Allows you to select Linear method to calculate the 
valve size.
Quick Opening 
radio button
Allow you to select Quick Opening method to calculate 
the valve size.
Equal 
Percentage radio 
button
Allows you to select Equal Percentage method to 
calculate the valve size.
User Table radio 
button
Allows you to specify the valve characteristics curve 
values used to calculate the valve size. When selected, 
a View button appears. The View button gives you 
access to the Characteristics Curve property view.
Refer to Theory section 
for more information 
about each calculation 
method.
Refer to Sizing Methods 
Group section for more 
information.
Refer to Characteristics 
Curve Property View 
section for more 
information.6-141
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6-142 Valve
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ThCharacteristics Curve Property View
The Characteristics Curve property view contains a table, two 
buttons, and a plot: 
When you first open the Characteristics Curve property view, the 
Lift (% of max) and Flow (% of max) columns contain two 
mandatory values (0 and 1.0) and three default values (0.25, 
0.5, and 0.75).
Control Valve Calculation Theory
In HYSYS there are four different methods to characterize the 
control valve. All four methods use the following parameters to 
calculate the control valve.
The flow rate through a control valve depends on the actual 
valve position. If the flow can be expressed in terms of %Cv 
(e.g., 0% representing no flow conditions and 100% 
representing the maximum flow conditions), then the valve 
characteristics of a control valve are defined as the dependence 
of the quantity of %Cv on the actual valve percent opening.
Object Description
Lift (% of max) 
column
Allows you to specify the valve stem position 
percentage value. The values are limited to a range of 
0 to 100.
Flow (% of max) 
column
Allows you to specify the percentage flow rate 
associated to the valve stem position. The values are 
limited to a range of 0 to 100.
Erase Selected 
button
Allows you to erase the selected percentage stem 
position and percentage flow rate values.
Erase All button Allows you to erase all the values in the Curve 
Information table.
Plot Displays the characteristics curve based on the values 
specified in the Curve Information table.
The table must contain at least three points to calculate the 
characteristics curve of the valve operation. 
If the values in the Curve Information table is not valid and 
the User Table method has been selected, then you will not 
be able to run the valve in dynamic mode.6-142
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ThThree methods use equation models based on three different 
types of valves:
Valve Type Description
Linear A control valve with linear valve characteristics has a flow 
which is directly proportional to the valve % opening.
The mathematical relationship of Cv (%) and Valve Position 
(%) for Linear valve is as follows:
(6.57)
Quick 
Opening
A control valve with quick opening valve characteristics 
obtains larger flows initially at lower valve openings. As the 
valve opens further, the flow increases at a smaller rate.
The mathematical relationship of Cv (%) and Valve Position 
(%) for Quick Opening valve is as follows:
(6.58)
Equal 
Percentage
A control valve with equal percentage valve characteristics 
initially obtains very small flows at lower valve openings. 
However, the flow increases rapidly as the valve opens to 
its full position.
The mathematical relationship of Cv (%) and Valve Position 
(%) for Equal Percentage valve is as follows:
(6.59)
%Cv %Valve Opening=
%Cv
100
------------ (%Valve Opening/100)0.5=
%Cv
100
------------ (%Valve Opening/100)3=6-143
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6-144 Valve
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ThThe inherent valve characteristics are shown graphically in the 
figure below.
The fourth method uses a table filled with values of the valve 
stem positions and the associated percentage flow capacity 
characteristic curves to calculate the operating characteristics. 
In other words, the fourth method does not rely on an equation 
to predict the control valve flow characteristics, instead it relies 
on values supplied by the user.
The calculation is done by using simple quadratic interpolation 
from the three points in the table closest to the current stem 
position.
 Figure 6.75
0 20 40 60 80 100
0
20
40
60
80
100
Quick 
Opening
Linear
Equal 
Percentage
% Valve Position
%
 C
v
CONTROL VALVE FLOW CHARACTERISTICS6-144
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Piping Operations 6-145
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ThSizing Methods Group
The Sizing Methods group contains four radio buttons and a 
table.
Two radio buttons pertain to parameter manipulation:
Two radio buttons pertain to the sizing method:
The table lists the available parameters:
Object Description
Cv radio 
button
Allows you to select Cv as the parameter to manipulate the 
resistance equation in the flow calculation.
Cg radio 
button
Allows you to select Cg as the parameter to manipulate the 
resistance equation in the flow calculation.
Object Description
Fisher 
Universal
Uses the pre-HYSYS 2006.5 sizing method for valve sizing.
ANSI/ISA Uses the industry-standard ANSI/ISA S75.01 for valve 
sizing.
The ANSI/ISA valve sizing option is not activated when the 
user selects either the Universal Gas Sizing or Simple 
Resistance Equation option from the Valve Manufacturers 
drop-down list.
Object Description
C1 Allows you to specify the ratio value of Cg/Cv.
Km Allows you to specify the pressure recovery coefficient. This 
coefficient is used in choked liquid flow calculations.
Cv Allows you to specify the fluid flow rate (Cv) value. This cell 
is only active if you select Cv radio button.
Cg Allows you to specify the gas sizing coefficient. This cell is 
only active if you select Cg radio button.
k Allows you to specify the k value for the Simple Resistance 
equation method. 
This cell is only available if you select Simple resistance 
equation in the Valve Manufacturer group.
Fl Allows you to specify the liquid pressure recovery factor.
This cell is only available if you select the ANSI/ISA sizing 
method.6-145
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6-146 Valve
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ThSizing Theory
HYSYS supports two sizing calculation methods - the old Fisher-
based method, and the new ANSI/ISA sizing calculations. The 
essential difference (with the exception of the Simple Resistance 
Equation) in the old sizing method lies in the constants and 
equations that are employed in calculating the flow rate within 
the valve. The new ANSI/ISA procedure employs the same set 
of flow equations for all manufacturers and valve types. The 
difference between manufacturers, valve types, style and trim 
using the ANSI/ISA method is only reflected in the vendor-
calibrated constants in the global sizing equations (Xt, Fl, and 
Fp).
The difference between the manufacturers and types is the 
equations and constants used to calculate the flow rate within 
the valve. All valve manufacturers and types have Cv and Cg 
methods to calculate flow rate.
Fisher Universal Sizing Method
The following equations provide an example of the sizing 
method calculation for Fisher Sizing valve:
• The Cv- and Cg-based flow equation calculates the vapor 
flow through the valve using the following equation:
Fp Allows you to specify the piping geometry factor.
This cell is only available if you select the ANSI/ISA sizing 
method.
Xt Allows you to specify the terminal pressure drop.
This cell is only available if you select the ANSI/ISA sizing 
method.
Size Valve 
button
Allows you to specify a single valve parameter, while HYSYS 
calculates the remaining parameter values based on the 
stream and valve conditions (the conditions are taken from 
the Sizing Conditions group). HYSYS provides a C1 default 
value of 25.
(6.60)
Object Description
f lb hr⁄( ) υfracfac1.06Cg ρ lb ft⁄ 3( ) P1× 59.64
C1
------------ 1
P2
P1
-----– cpfac×
⎝ ⎠
⎜ ⎟
⎛ ⎞
sin×=6-146
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Piping Operations 6-147
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Thwhere:
P1 = pressure of the inlet stream
P2 = pressure of the exit stream without static head 
contributions
 = 1, outlet molar vapour fraction vfrac > 0.1
= 0, outlet molar vapour fraction vfrac = 0
= vfrac/0.1, otherwise
• For the liquid flow through the valve, the equation is as 
follows:
HYSYS reports the full Cv (at 100% open, which remains fixed) 
plus the valve opening. If the Valve is 100% open, then you get 
a smaller Valve than if the Valve was only 50% open for the 
same conditions. This is just one way of sizing a Valve, as some 
sources report an effective Cv (varies with the valve opening) 
versus the value opening. 
(6.61)
(6.62)
(6.63)
(6.64)
(6.65)
The above equations are not rigorous for two-phase flow.
C1
Cg
Cv
-----=
Km 0.001434C1=
cpfac
0.4839
1 2
1 γ+
-----------⎝ ⎠
⎛ ⎞
γ
γ 1–
----------⎝ ⎠
⎛ ⎞
–
---------------------------------------=
γ Cp Cv⁄=
υfracfac
f lb hr⁄( ) 1 υ– fracfac〈 〉 63.338× C× v ρ lb ft⁄ 3( )× P1 P2–×=6-147
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6-148 Valve
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ThANSI/ISA Sizing Method
The ANSI/ISA sizing method implements the industry standard 
ANSI/ISA S75.01 for valve sizing. The ANSI/ISA is generally 
considered state-of-the-art in valve sizing and more accurate 
than the old Fisher-based sizing equations.
The ANSI/ISA sizing procedure introduces three new vendor-
specific parameters to size a valve for a given application:
• Piping geometry factor, Fp
• Terminal pressure drop ratio, XT
• Liquid pressure recovery factor, Fl
The Fl and XT parameters are functions of the valve type, trim 
style, and flow direction that are supplied by the valve 
manufacturer.
The general flow equation for a two-phase flow is given by:
where:
Pu = the upstream pressure
Pd = the downstream pressure
vfrac = the weight fraction of vapor of total flow
Cv = the flow coefficient
f = the flow rate
 = the specific weight at inlet conditions in lb/ft3
Y = the gas expansion factor
The ANSI/ISA valve sizing option is not activated when the 
user selects either the Universal Gas Sizing or Simple 
Resistance Equation option from the Valve Manufacturers 
drop-down list.
(6.66)
 
uuvp
duvphrIb
psiaPxYCFvfrac
PPftIbCFvfracf
γ
ρ
).(.****338.63*
*)/(***338.63*)0.1( 3
/ +−−=
γ
6-148
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Piping Operations 6-149
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ThThe gas expansion factor Y is calculated using:
where:
x = the pressure drop ratio, 
The piping geometry factor (Fp) in the general flow equation is a 
dimensionless quantity that approximates the influence of pipe 
fittings, reducers, or increasers that are connected to the valve. 
For example, Fp is equal to 1 if the diameters of the inlet and 
outlet pipes are equal. The default value of Fp is 1.0 in HYSYS. 
In cases where the valve inlet and outlet diameters are 
different, obtain the Fp value from the valve manufacturer’s 
catalog.
The liquid pressure recovery factor (Fl) corresponds to Km in 
the Fisher-based sizing method. It indicates the amount of 
pressure recovery between the valve’s vena-contracta and the 
outlet stream. Generally, the higher the value of the liquid 
pressure recovery factor, the greater the pressure drop that can 
be accommodated by the valve before the inception of choked 
flow condition. HYSYS sets the allowable pressure drop based on 
the calculated pressure drops at the choked and service 
conditions. 
The pressure drop at choked or critical flow for liquid flow is 
estimated using:
where:
FF = the liquid critical pressure ratio, 
(6.67)
Note that for choked flow condition, FkXT is used in place of x 
in Equation (6.66) and Equation (6.67).
(6.68)
Y 1.0 x
3.0FkXT
--------------------–=
Pu Pd–
Pu
-----------------
PchokedΔ Fl
2 Pu FFPv–( )=
0.96 0.28
Pv
Pc
-----–6-149
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6-150 Valve
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ThPv = the vapor pressure of the liquid at the flow temperature
Pc = the liquid critical pressure
The pressure drop at service condition is given by:
The lower of  and  is employed as the allowable 
pressure drop for liquid flow valve sizing.
XT is the equivalent of the Fl factor in valve sizing for 
compressible fluids, i.e., gas and steam flow. The pressure drop 
ratio for compressible flow at service condition is given by:
Note that the allowable pressure drop ratio is limited to the 
terminal pressure drop ratio, XT, which is given by:
where:
Fk = 
k = the ratio of specific heats, 
In HYSYS, XT is set to a default value of 0.7.
(6.69)
(6.70)
(6.71)
 Except for slight differences in nomenclature and 
procedures, the ANSI/ISA S75.01 is generally compatible 
with the formulations of IEC-534-2 (International 
Electrotechnical Commission) for valve sizing.
PΔ Pu Pd–=
PchokedΔ PΔ
x
Pu Pd–
Pu
-----------------=
x FkXT=
k
1.4
------
cp
cv
----6-150
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Piping Operations 6-151
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ThValve Vapor Flow Models
The dropdown box of Valve Manufacturers is only used for sizing 
vapor/gas flows. This section summarizes the major gas flow 
equations for 6 valve manufacturers 
• Masoneilan
• Mokveld
• Fisher
• Introl
• Valtek
• CCI Drag
plus the two phase flow calculations for the Handle multi-
phase flows rigorously option.
The following common variables are applied to all 6 valve 
manufacturers.
Input:
Pu = upstream pressure (bara)
Pd = downstream pressure (bara)
Cv = valve input coefficient - effective opening of the valve 
(metric)
Output:
Fv = vapor or gas mass flowrate (kg/hr)
Valve Vapor/Gas Flow Equations
Given upstream and downstream pressures and an effective 
valve Cv, HYSYS Dynamics calculates the vapor/gas mass 
flowrates using flow equations appropriate to the valve 
manufacturer. HYSYS Dynamics uses a general liquid flow 
equation (Fisher Liquid Flow Equation) to calculate the liquid 
phase applications for all valve types: 
(6.72)pcv
%Cv
100
-----------=6-151
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ThIf pcv > 1.0, then set pcv  = 1.0
Masoneilan
The parameters: a, b, c, d, e will depend on the valve types. 
(6.73)
(6.74)
(6.75)
Valve Type Parameters
DP GLOBE : V-PORT a = 0.998
b = 0.1179
c = 0.2632 
d = 0.2583
e = 0.09324
40000, 41000 SERIES a = 0.9989
b = 0.2620
c = 0.5573
d = 0.6765
e = 0.3059
SP GLOBE: FLOW-TO-
OPEN
a = 0.9986
b = 0.3776
c = 0.833
d = 0.9673
e = 0.4137
CAMFLEX: FLOW-TO-
OPEN
a = 0.9985 
b = 0.5354
c = 0.9630
d = 0.9487
e = 0.3729
SPLIT BODY: FLOW-TO-
OPEN
a = 0.9917
b = 0.9523
c = 2.543
d = 3.474
e = 1.646
G Mw 28.96⁄=
ΔP Pu Pd–=
Cf a b pcv c pcv2 d pcv3 e pcv4×+×–×+×–=6-152
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Piping Operations 6-153
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ThTo see if the valve has a critical flow:
If Y < 1.5, then it is a non-critical flow.
CAMFLEX: FLOW-TO-
CLOSE
a = 0.9982
b = 0.5302
c = 0.3471
d = 0.2068
e = 0.07264
BUTTERFLY (MINITORK) a = 0.9060
b = 0.5169
c = 0.3805
d = 0.1185
e = 0.00000298
CONTROL BALL a = 0.9187
b = 0.2269
c = -0.6245
d = -0.6672
e = -0.1311
SPLIT BODY: FLOW-TO-
CLOSE
a = 0.5439
b = 0.7677
c = 7.184
d = 12.14
e = 5.944
GLOBE: CONTOURED a = 0.6308
b = 0.5227
c = 6.545
d = 11.36
e = 5.626
GLOBE: FLOW-TO-CLOSE a = 0.5470
b = 0.9956
c = 8.523
d = 13.73
e = 6.526
(6.76)
Valve Type Parameters
Y
1.63 ΔP Pu⁄
Cf
--------------------------------=6-153
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6-154 Valve
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ThIf Y >= 1.5, it is a critical flow; set Y = 1.5.
Mokveld
The parameters: a, b, c, d, e will depend on the valve types. 
(6.77)
(6.78)
(6.79)
Valve Type Parameter
RZD-R a = 0.9929
b = 2.805
c = 6.916
d = 7.639
e = 3.030
RZD-RES a = 0.891
b = 1.427
c = 2.826
d = 2.785
e = 1.049
RZD-RVX a = 0.6918
b = 2.563
c = 9.101
d = 12.03
e = 5.244 
temp
0.397771 27.32 C× v Cf Mw×××
G t 273.15+( )× z×
--------------------------------------------------------------------------------=
Fv temp Pu Y 0.148Y3·
–⎝ ⎠
⎛ ⎞××=
Cf a b pcv c pcv2 d pcv3 e pcv4×+×–×+×–=6-154
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Piping Operations 6-155
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ThTo see if it is critical flow:
If , then it is a non-critical flow.
If , it is a critical flow; set Y = 1.5..
Fisher
This method is based on the Fisher valve equation.
RZD-REVX a = 0.9512
b = 1.212
 c = 3.197
d = 3.661
e = 1.456
RZD-RCX a = 0.9275
b = -0.0001306
c = -0.4872
d = -0.3888
e = -0.04661
(6.80)
(6.81)
(6.82)
(6.83)
Valve Type Parameter
Y
1.63 ΔP Pu⁄
Cf
--------------------------------=
Y 1.5<
Y 1.5≥
temp
0.392666 27.32 C× v Cf×× Mw×
G t 273.15+( )× z×
--------------------------------------------------------------------------------=
Fv temp Pu Y 0.148Y3·
–⎝ ⎠
⎛ ⎞××=
vk1 0.0004444 Mw t 273.15+( )⁄ 1.0e 6–+
·
=
6-155
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6-156 Valve
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ThIf Pr > 1.0 – 1e-6, then Pr = 1.0 – 1e-6.
If vk2 > 3.14159/2.0 (or ), then a sonic flow occurs (it is a 
critical flow), and vk2 is limited to /2.
Introl
The parameters: a, b, c, d, e will depend on the valve types. 
(6.84)
(6.85)
(6.86)
(6.87)
Valve Type Parameter
1. SERIES 10 FLOW-TO-
OPEN
a = 0.9993
b = 0.325
c = 0.5843
d = 0.5971
e = 0.2389
2. SERIES 20 FLOW-TO-
OPEN&CLOSE
a = 0.5331
b = -1.086
c = -0.03679
d = 2.082
e = 1.407
3. SERIES 10 FLOW-TO-
CLOSE
a = 0.5049
b = -0.1387
c = 4.115
d = 7.965
e = 4.076
Pr
Pd
Pu
-----=
vk2 59.6379 C1⁄( ) 1.0 Pr–=
π 2⁄
π
Fv vk1 Cv Pu vk2sin C1 3600×××××=
Cf a b pcv c pcv2 d pcv3 e pcv4×+×–×+×–=6-156
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Piping Operations 6-157
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Th4. SERIES 60A a = 0.9184
b = 0.1115
c = -0.5018
d = -0.1855)
e = 0.1311
5. SERIES 60 a = 0.9194
b = 0.07341
c = -1.228
d = -1.403;
e = -0.4458
6. SERIES 10 HF a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
7. SERIES 20 H a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
8. SERIES 10 HFD a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
9. SERIES 20 HFD a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
10. SERIES 10 HFT a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
11. SERIES 20 HFT a = 1.0
b = 0.0
c = 0.0
d = 0.0
e = 0.0
Valve Type Parameter6-157
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6-158 Valve
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ThTo calculate pressure drop limit:
To see if it is critical flow:
If P > dPlimit, then it is a critical flow; set P = dPlimit.
Otherwise, it is a non-critical flow.
(6.88)
(6.89)
(6.90)
(6.91)
Fk
cpcv
1.4
-----------=
dPlimit bar_cf2 Fk introlR Pu×××=
Δ Δ
temp
S2–
Fk
S2
---------=
Kx S1 1 ΔP
Pubar_cf2
-----------------------–
⎝ ⎠
⎜ ⎟
⎛ ⎞ temp
=
6-158
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Piping Operations 6-159
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ThIf Kx < 1.0, set Kx = 1.0
Finally, calculate the gas flow:
Valtek
The parameter Xt depends on the valve types. 
Valve Type Parameters
For single stage trims 
from valve types of 1) to 
7)
bar_cf = 1.33 * Cf
introlR = 0.47
S1 = 1.0
S2 = 0.65 
S3 = 0.92
If Kx > 1.6, then set Kx = 1.6
VHfactor = 1.0
For two stage trims from 
valve types of 8) and 9)
bar_cf = 1.18 * Cf
introlR = 0.65
S1 = 0.97
S2 = 0.53
S3 = 0.90
If Kx > 1.8, then set Kx = 1.8
VHfactor = 1.0 + 0.33 * P / Pu
For three stage trims 
from valve types of 10) 
and 11)
bar_cf = 1.11 * Cf
introlR = 0.75
S1 = 0.90
S2 = 0.60
S3 = 1.0
If Kx > 2.0, then set Kx = 2.0
VHfactor = 1.0 + 0.48 * P / Pu 
(6.92)
Valve Type Value of Xt
MARK ONE FLOW-TO-
OPEN
0.75
MARK TWO FLOW-TO-
OPEN
0.75
MARK ONE FLOW-TO-
CLOSE
0.70
MARK TWO FLOW-TO-
CLOSE
0.70
Δ
Δ
Fv 0.994053VHfactor Kx⁄ Cv× 27.32× ΔP Dvap× 1.0e 6–+×=6-159
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6-160 Valve
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ThTo check for choked flow:
If Pu > 1.0e-6:
xp = P/Pu
If  < 1.0e-6, then  xp =1 .0e-6
If , then xp = xt * Fk
If xp > xt * Fk, then it is critical flow; set xp = xt * Fk.
If Fk < 1.0e-6, set Fk = 1.0e-6.
If xt < 1.0e-6, set xt = 1.0e-6.
If z < 0.1, set z = 0.1.
VECTOR ONE  60 DEG 0.38
VECTOR ONE  90 DEG 0.20
DRAGON TOOTH 1.0
(6.93)
(6.94)
(6.95)
Valve Type Value of Xt
Fk
cpcv
1.4
-----------=
Δ
xp
Pu 1.0e 6–≤
y 1.0
Xp
3FRXt
---------------–=
Fv 3.464= C1× Cv× 27.32× Pu× Y×
xp Mw×
z t 273.15+( )
------------------------------- 1.0e 6–+×6-160
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ThCCI Drag 
If z < 0.1, set z = 0.1.
Fk = cpcv / 1.4
If Fk < 1.0e-6, set Fk = 1.0e-6.
If Pu > 1.0e-6
  xp =  P / Pu
  Y = 1.0 -  
Otherwise, xp = 0.0 and Y = 1.0.
where:         
open% = Percent of valve opening 
pcv = Fraction of rated Cv
Mw = Molecular weight of vapor phase from upstream 
G = Parameter = Mw / 28.96
P = Pressure drop 
Pu = Upstream pressure (bara)
Pd = Downstream pressure (bara)
Cf = Valve critical flow factor
Y = Gas expansion factor 
temp, vk1, vk2 = Temporary variables
Cv = Valve flow coefficient
C1 = Cg/Cv , a parameter input which is a function of body 
size of valve and line size 
t = Vapor phase temperature from upstream (C) 
(6.96)
Δ
xp
3.0Fk
-------------
Fv 3.453134= C1× Cv× 27.32×
Mw
t 273.15+( ) z 1.0e 6–+×
----------------------------------------------------------- Y Pu× xp×××
Δ
6-161
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6-162 Valve
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Thz = Upstream compressibility factor in vapor phase
Fv = Vapor or gas flowrate (kg/hr)
Pr = Pressure ratio of Pd/Pu
Fk = cpcv/1.4
cpcv = Rigorous Cp/Cv, ratio of specific heats
dPlimit = Pressure drop limit
bar_cf, introlR, S1, S2, and S3 = Parameters used in valve 
equations
Kx = Expansion correction factor
VHfactor = Reheat factor, depending on the number of stage 
trim
Dvap = Mass density in vapor phase (kg/m3)
Xt = Pressure drop ratio factor (valve specific)
xp = Ratio of pressure drop to inlet press 
“Handle multi-phase flows rigorously” option
This process will iteratively be calculated until full convergence 
to final Ftotal.
 
Fm = f (Vgas) is a function of Vgas, which is based on the 
following data:
Vgas [15]= {0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, .85, 0.9, 
.925, 0.95, 0.99,1}
Fm [15] = {0, 0.092, 0.184, 0.276, 0.371, 0.469, 0.576, 0.711, 
0.876, 0.965, 1.0, 0.980, 0.91, 0.50, 0}
Cvr = (Cvl + Cvg) * (1.+ Fm) = (Cv + Cg/C1) * (1. + Fm)
αl Fl Cv⁄=
αv Fv C1 Cg⁄×=
Vmf Vf Mw
v Vf Mw
v× 1 Vf–( ) Mw
l×+( )⁄×=
Vgas Vmf Dvap⁄ Vmf Dvap⁄ 1 Vmf–( ) Dliq⁄+( )⁄=6-162
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ThIf Vmf = 0, then Ftotal =  * Cvr
If Vmf = 1.0,  then Ftotal =  * Cvr
Otherwise, 
where:
Fl = Mass flow for liquid phase
Fv = Mass flow for vapor phase, same as Fv above developed 
by different valve manufacturers
Cv = Standard liquid sizing coefficient
Cg = Cg for gas phase
C1 = Cg/Cv ratio for valve
Cvl = Cv for liquid phase, Cvl = Cv
Cvg = Cv required for gas phase = Cg/C1
Cvr = Cv required for mixture flow
Vmf = Vapor mass fraction
Vf = Vapor molecular fraction
Mw
v = Vapor molecular weight
Mw
l = Liquid molecular weight
, - Parameters
Denom = Denominator of  and 
Vgas = Gas volume ratio
Fm = Cv correction factor, a function of the gas volume ratio
Dvap = Mass density of vapor phase
Dliq = Mass density of liquid phase
Ftotal = Overall mass flowrate
Denom αv 1 Vmf–( )× αl Vmf×+=
αl
αv
Ftotal αv αl Cvr Denom 1 Fm+( )⁄⁄××=
αl αv
αl αv6-163
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ThSimple Resistance Equation
If the Simple Resistance Equation is chosen, you can either:
• Specify k value.
• Have k calculated from the stream and valve conditions 
displayed in the Sizing Conditions group. To calculate k 
value, specify the required variable values and click the 
Size Valve button. 
The Simple Resistance Equation method calculates the flow 
through the Valve using the following equation:
The general valve flow equation uses the pressure drop across 
the Valve without any static head contributions. The quantity, P1 
- P2, is defined as the frictional pressure loss, which is used in 
the valve sizing calculation. The valve opening term is 
dependant on the type of Valve and the percentage that it is 
open. For a linear valve:
The inverse relationship between the percentage of valve 
opening, and Cg can be shown as follows:
When the valve size is fixed, the percentage of valve opening 
increases with the flow through the valve. However, when sizing 
a valve, the Cg is not fixed. The Cg is inversely dependent on the 
flow, and the percentage of valve opening.
(6.97)
(6.98)
(6.99)
f k density valveopening× P1 P2–( )×=
valveopening % valve open
100
--------------------------------⎝ ⎠
⎛ ⎞ 2
=
% valve open( ) Cg× Flow=6-164
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ThNozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. 
Options Page
The Options page enables you to select the method to handle 
multiphase streams.
• The Handle densities for multi-phase systems 
rigorously checkbox enables the valve to use the phase 
densities to calculate flow rate for the vapour and liquid. 
If the option was not selected the overall density is used.
• The Handle multi-phase flows rigorously checkbox 
enables the valve to use rigorous calculation method and 
obtain better accuracy of the flow rates and pressure 
drop for both vapour and liquid flow. The calculations 
have been improved to be consistent with the Fisher 
calculations for multiphase systems.
 Figure 6.76
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.6-165
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Th6.7.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation.
 
6.7.5 Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Pipe
• Holdup
• Actuator
• Flow Limits
• Stripchart
The PF Specs page is relevant to dynamics cases only.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab. 
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.6-166
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ThSpecs Page
The dynamic specifications and parameters of the Valve can be 
specified on the Specs page.
Dynamic Specifications
If the Total Delta P checkbox is selected, a set pressure drop is 
assumed across the Valve operation. With this specification, the 
flow and the pressure of either the inlet or exit stream must be 
specified or calculated from other operations in the flowsheet. 
The flow through the Valve is not dependent on the pressure 
drop across the Valve.
If the Pressure Flow Relation checkbox is selected, two of the 
following pressure-flow specifications must either be specified or 
calculated by the other unit operations in the flowsheet:
• Inlet Stream Pressure
• Exit Stream Pressure
• Flow through the Valve
 Figure 6.77
In Dynamic mode, there are two possible dynamic 
specifications you can choose to characterize the Valve 
operation.6-167
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ThThe flow rate through the Valve is calculated from the valve 
equation, and the pressure of the streams entering and exiting 
the Valve.
In dynamics, the suggested mode of operation for the Valve is 
the Pressure Flow specification. The pressure drop option is 
provided for steady state compatibility mostly, and to allow 
difficult simulations to converge more easily. However, it usually 
is not a sensible specification since it allows a pressure drop to 
exist with zero flow.
Dynamic Parameters
The Dynamic Parameters group lists the same stream and valve 
conditions required to size the Valve as in the Sizing Conditions 
group. The Valve Opening % and the Conductance (Cv or k) 
appear and can be modified in the section. The conductance of 
the Valve can be calculated by clicking the Size Valve button.
The Check Valve checkbox can be selected if you do not want 
flow reversal to occur in the Valve.6-168
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ThPipe Page
The Valve module supports a pipe contribution in the pressure 
flow equation.
This can be used to model a pipe segment in the feed to the 
Valve, but it is also possible to disable the valve contribution and 
have the Valve unit operation act as a simple pipe segment only. 
The pressure flow specification has to be enabled in order for 
the pipe segment to be modeled.
The following pipe modeling parameters appear in this section:
 Figure 6.78
A pipe contribution DOES NOT contribute to any holdup 
volume. You have to enter the holdup separately in the 
Holdup Page.
The pipe calculations for a valve are not rigorous for 
multiphase flow and are only approximations.
• Friction Factor 
Equation
• Material
• Roughness
• Pipe length
• Feed diameter
• Darcy friction factor
• Pipe k
• Velocity
• Reynolds number6-169
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ThFriction Factor
The Friction Factor Equation option allows you to choose 
between two different equations:
• Assume Complete Turbulence (f is fixed)
Assume Complete Turbulence is the default equation, 
and the calculation is fast and simple. This method 
calculates the friction factor once and uses that value 
irrespective of the Reynolds number (the calculated 
friction factor value is not correct if the flow is laminar).
• Full-Range Churchill (covers all flow regimes)1,7
The Full-Range Churchill method calculates the friction 
factor as a function of the Reynolds number. This method 
is slower but calculates a unique friction factor for the 
turbulent, lamiar, and transtitional regions. If the flow 
through the Valve is too low HYSYS uses a low limit of 10 
for the Reynolds number.
HYSYS suggests a typical pipe roughness if the pipe material is 
specified. The pipe roughness may also be directly specified. 
The feed diameter and pipe length must be specified as well. 
These specifications are used to determine the Darcy friction 
factor.
The friction factor is calculated as follows:
where:  
fDarcy = Darcy friction factor
D = pipe diameter
 = pipe roughness
Assume Complete Turbulence equation:
(6.100)
Full-Range Churchill equation:
(6.101)
(6.102)
1
ffriction
--------------------- 2.457 3.707D
ε
-----------------⎝ ⎠
⎛ ⎞ln=
ffriction
8
Re
------⎝ ⎠
⎛ ⎞ 12 1
A B+( )1.5
-----------------------+
1 12⁄
=
fDarcy 8 ffriction×=
ε
6-170
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ThA pipe k-value is calculated from the Darcy friction factor and 
the pipe diameter. The pipe k value is incorporated into the 
general valve equation. 
Notice that this pipe k is independent of the flow rate or 
pressure of the fluid in the Valve.
Holdup Page
The Holdup page contains information regarding the holdup 
properties, composition, and amount.   
The pipe segments only calculate frictional losses. They do 
not automatically calculate holdup volume. You must enter 
this on the Holdup page of the Dynamics tab.
 Figure 6.79
Each unit operation in HYSYS has the capacity to store 
material and energy. Typical Valves usually have 
significantly less holdup than other unit operations in a 
plant. Therefore, the volume of the Valve operation in HYSYS 
is defaulted to be zero. 
A 2.457 1
7
Re
------⎝ ⎠
⎛ ⎞ 0.9
0.27 ε
D
---⎝ ⎠
⎛ ⎞+
---------------------------------------------ln
16
=
B 37530
Re
--------------⎝ ⎠
⎛ ⎞ 16
=
Refer to Section 1.3.3 - 
Holdup Page for more 
information. 6-171
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ThThe Holdup page allows you to:
• Specify a non-zero value (in the Holdup Volume field) 
for the holdup volume in the Valve.
• Disable any flashes that may occur in the Valve.
The Disable flashes checkbox enables you to turn on and off 
the rigorous flash calculation for the valve. This feature is useful 
if the PFD has a very large number of valves, and you do not 
care whether the contents of the streams around them are fully 
up to date or not, or you prefer maximum speed in the 
simulation calculation.
• To turn off the flash calculation, select the Disable 
flashes checkbox.
If the flash calculations are turned off, the outlet stream 
will still update and propagate values, but the phase 
fractions and temperatures may not be correct.
• To turn the flash calculation back on, clear the Disable 
flashes checkbox.
The default selection is to leave the flash calculation on.
The HYSYS Dynamics license is required and the Access 
Fidelity license options checkbox selected in the Options tab 
of the Integrator property view, to set a non-zero holdup.
Holdup occurs after the valve, whereas the pipe contribution 
occurs before the valve.
HYSYS recommend that the flash calculations be left on, as 
in some cases disabled flash calculation can result in 
instabilities or unexpected outcomes, depending on what is 
downstream of the unit operation where the flash has been 
turned off. This feature should only be manipulated by 
advanced users.
Refer to Section 2.4 - 
Integrator in the HYSYS 
Dynamic Modeling 
guide for more 
information.6-172
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ThActuator Page
The Actuator page allows you to model valve dynamics in the 
Valve operation. The HYSYS Dynamics license is required to use 
the Actuator features found on this page. 
Flow Limits Page
The Flow Limits page allows you to monitor the status of the 
vapour and liquid flow passing through the valve. The page 
consists of two groups:
• Vapour Choking
• Liquid Choking
Vapour Choking Group
By default, the Vapour Choking status is always monitored 
whenever it is applicable. You can view the current condition of 
the vapour flow in the Vapour Choking Status group. The active 
status is shown in black whereas the inactive status is greyed 
out. The two statuses available are Critical Flow and No Choking. 
Critical flow or vapour choking refers to the crowding condition 
when the gas flowing through the valve has exceeded the 
designed limit and reaches the sonic velocity. 
 Figure 6.80
Refer to Section 1.6.3 - 
Control Valve Actuator 
in the HYSYS Dynamic 
Modeling guide for more 
information.6-173
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ThCritical flow is calculated by the Fisher equation for gases.
where:  
f = flow (lb/hr)
Vfrac = vapour fraction
Cg = Fisher’s valve vapour coefficient
C1 = critical flow factor, Cg/Cv (between 33 - 38)
Cpfac = theoretical correction factor for the ratio of specific 
heats
 = density (lb/ft3)
P1 = pressure at valve inlet (psia)
P2 = pressure at valve outlet (psia)
As the Sine function approaches to 1, the flow through the valve 
becomes choked and under this condition, the vapour through 
the valve undergoes critical flow.
(6.103)f Vfrac 1.06 Cg ρ P1
59.64
C1
------------ 1
P2
P1
------–× Cpfac
×
⎝ ⎠
⎜ ⎟
⎛ ⎞
sin×××××=
ρ
6-174
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ThLiquid Choking Group
Liquid choked modeling is optional in HYSYS. You can turn it on 
or off for the associated valve by selecting the Model Liquid 
Choking checkbox.
The  Liquid Choking Status group contains three flow conditions:
• No choking. Normal flow condition. An increase in 
pressure drop across the valve results in an increased 
flow. The No choking condition holds for a limited range.
• Flashing. When the pressure of the valve outlet falls 
below the vapour pressure of the liquid.
• Cavitating. When the pressure of valve outlet raises 
above the vapour pressure of the liquid.
The presence of these flow conditions can significantly affect the 
valve performance and the overall process. During flashing, 
liquid starts to vapourize, and the change in phase from liquid to 
vapour causes bubbles to form. This creates congestion across 
the valve (liquid choking), and the flow is severely limited. At 
this point, increase in pressure drop will not result in increased 
flow. When cavitation occurs, the pressure of the liquid recovers 
and raises above its vapour pressure. This causes vapour 
bubbles to collapse and burst, producing a great amount of 
noise and vibrations that can damage the valve.
 Figure 6.81
You can also select the 
Model Liquid Choking 
checkbox on the Options 
tab of the Integrator 
property view.6-175
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ThSince the regular Fisher liquid flow equation does not predict 
liquid choked flow, a different equation is used to take into 
account the effects of flashing and cavitation.
Km (the pressure recovery coefficient) predicts flashing and 
cavitation for a valve. By default, the pressure recovery 
coefficient is set at a conservative value of 0.9. You can specify 
the Km value to adjust the flow condition.
The liquid choked-flow condition is shown in Figure 7.73. As 
pressure drop increases, the liquid flow becomes choked. The 
allowable pressure drop ( ) indicates when the liquid 
choked-flow occurs and it is defined as: 
where:  
Km = pressure recovery value
rc = critical pressure ratio
Pv = vapour pressure of liquid
 Figure 6.82
(6.104)
q,
 g
pm
ΔP
Flow equation
prediction
ΔPallowable ΔPmax
Choked flow
ΔPallowable
ΔPallowable Km P1 rcPv–( )=6-176
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ThThe values of these parameters are displayed in the table. The 
Frictional Delta P shows the current pressure drop across the 
valve. As you adjust the pressure recovery coefficient, the 
Frictional Delta P allowable changes according to Equation 
(7.60). The Liquid Vapour pressure and the Critical Pressure 
Ratio are also displayed for reference. 
No message is displayed when the flow consists of vapour and 
liquid.
 Figure 6.83
If the Frictional Delta P allowable is below the Frictional 
Delta P, then cavitation occurs.
 Figure 6.84
If the flow is 
vapour dominant, 
HYSYS displays 
this message 
even if the Model 
Liquid Choking 
checkbox is 
selected.6-177
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6-178 References
ww
ThStripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation.
6.8 References
 1 American Gas Association on the "Engineering Data Book SI Volume 
II", 11th edition, GPSA, 1998, page 17.
 2 Aziz, K., Govier, G.A., and Fogarasi, M., Pressure Drop in Wells 
Producing Oil and Gas, Journal of Canadian Petroleum Technology, 
July-September 1972, pp 38-48.
 3 Baxendell, P.B., and Thomas, R., The Calculation of Pressure 
Gradients in High-Rate Flowing Wells, J. Pet. Tech., October 1961, 
pp 1023-1028.
 4 Beggs, H.D., and Brill, J.P., A Study of Two-Phase Flow in Inclined 
Pipes, J. Petrol. Technol., p. 607, May (1973).
 5 Brill, J.P., and Beggs, H.D., Two Phase Flow in Pipes, Sixth Ed, 
July 1989.
 6 Brill, J.P., and Mukherjee, H., Multiphase Flow in Wells, SPE 
Monograph, Volume 17.
 7 Churchill, S. W., Chem. Eng., 84(24), (1977), 91.
 8 Duns, H.Jr., and Ros, N.C.J., Vertical Flow of Gas and Liquid Mixtures 
in Wells, 6th World Petroleum Congress, Frankfurt, June 1963, pp 
451-465.
 9 Eckert, E.R.G. & Drake, R.M., “Analysis of heat and mass transfer”, 
HTFS Reference Number 60167, 1972.
 10Gregory, G.A., Mandhane, J. and Aziz, K., Some Design 
Considerations for Two-Phase Flow in Pipes, J. Can. Petrol. Technol., 
Jan. - Mar. (1975).
 11Hagedorn, A.R., and Brown, K.E., Experimental Study of Pressure 
Gradients Occurring During Continuous Two-Phase Flow in Small-
Diameter Vertical Conduits, Journal of Petroleum Technology, April 
1965, pp 475-484.
 12HTFS Handbook, Volume 2, Methods TP3, TM4, TM5
 13HTFS Handbook, Volume 2, Two Phase Flow.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.6-178
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Piping Operations 6-179
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Th 14Multiphase Flow and Subsea Separation. Special report by Smith 
Rea Energy Associates and UKAEA, April 1989.
 15Orkisewski, J., Predicting Two-Phase Pressure Drops in Vertical Pipe, 
Journal of Petroleum Technology, June 1967, pp 829-839.
 16Poettmann, F.H., and Carpenter, P.G., The Multiphase Flow of Gas, Oil 
and Water Through Vertical Flow Strings with Application to the 
Design of Gas-Lift Installations, Drill and Prod. Practice, API, pp. 
257-317, March 1952.
 17Smith, R.A. et al, Two Phase Pressure Drop, HTFS Design Report 28 
(Revised), 1981 (8 parts, 2 Appendices).
 18Tengesdal, J.Ø, Sarica, C., Schmidt, Z., and Doty, D., A Mechanistic 
Model for Predicting Pressure Drop in Vertical Upward Two-Phase 
Flow, Journal of Energy Resources Technology, March 1999, Vol 
121.
 19Watson, M., The modelling of slug flow properties, 10th International 
Conference Multiphase '01, Cannes, France, 13-15 June 2001.6-179
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6-180 References
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Th6-180
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Optimizer Operation 7-1
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Th7  Optimizer Operation7-1
7.1  Optimizer ....................................................................................... 2
7.1.1  General Optimizer Property View ................................................ 3
7.1.2  Configuration Tab ..................................................................... 4
7.2  Original Optimizer.......................................................................... 5
7.2.1  Variables Tab ........................................................................... 6
7.2.2  Functions Tab .......................................................................... 7
7.2.3  Parameters Tab ........................................................................ 9
7.2.4  Monitor Tab ........................................................................... 11
7.2.5  Optimization Schemes ............................................................ 12
7.2.6  Optimizer Tips ....................................................................... 17
7.3  Hyprotech SQP Optimizer............................................................. 18
7.3.1  Hyprotech SQP Tab................................................................. 19
7.4  MDC Optim................................................................................... 23
7.5  DataRecon ................................................................................... 24
7.6  Selection Optimization ................................................................. 24
7.6.1  Selection Optimization Tab....................................................... 24
7.6.2  Selection Optimization Tips...................................................... 34
7.7  Example: Original Optimizer ........................................................ 35
7.7.1  Optimizing Overall UA ............................................................. 40
7.8  Example: MNLP Optimization ....................................................... 44
7.8.1  NLP Setup ............................................................................. 50
7.8.2  MINLP Setup.......................................................................... 55
7.9  References................................................................................... 59
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Th7.1 Optimizer
HYSYS contains a multi-variable steady state Optimizer. Once 
your flowsheet has been built and a converged solution has been 
obtained, you can use the Optimizer to find the operating 
conditions which minimize (or maximize) an Objective Function. 
The object-oriented design of HYSYS makes the Optimizer 
extremely powerful, since it has access to a wide range of 
process variables for your optimization study.
The Optimizer owns its own Spreadsheet for defining the 
Objective Function, as well as any constraint expressions to be 
used. The flexibility of this approach allows you, for example, to 
construct Objective Functions which maximize profit, minimize 
utilities or minimize Exchanger UA.
The following terminology is used in describing the Optimizer.
The Optimizer is available for steady state calculations only. 
The operation does not run in Dynamic mode.
Terms Definition
Primary 
Variables 
These are the variables imported from the flowsheet whose 
values are manipulated in order to minimize (or maximize) 
the objective function. You set the upper and lower bounds 
for all of the primary variables, which are used to set the 
search range, as well as for normalization.
Objective 
Function 
The function which is to be minimized or maximized. There 
is a great deal of flexibility in describing the Objective 
Function; primary variables can be imported and functions 
defined within the Optimizer Spreadsheet, which possesses 
the full capabilities of the main flowsheet spreadsheet.
Constraint 
Functions
Inequality and Equality Constraint functions can be defined 
in the Optimizer Spreadsheet. An example of a constraint is 
the product of two variables satisfying an inequality (for 
example, -A*B RHS, LHS < RHS, LHS = RHS) 
in the Cond column. The Constraint Function is multiplied by the 
Penalty Value in the Optimization calculations. If you find that a 
constraint is not being met, increase the Penalty Value; the 
higher the Penalty Value, the more weight that is given to that 
constraint. The Penalty Value is equal to 1 by default.
The current values of the Objective Function and the left and 
right sides of the Constraint Function cells appear in their 
respective fields.
The Functions tab is only available if you select the Original 
configuration.
To open the Optimizer Spreadsheet, click the SpreadSheet 
button.
The BOX, Mixed, and SQP Methods allow for Inequality 
Constraints. Only the SQP Method incorporates Equality 
Constraints.
For information on using 
the Spreadsheet, refer 
to Chapter 5 - Logical 
Operations.7-8
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Th7.2.3 Parameters Tab
The Parameters tab is used for selecting the Optimization 
Scheme and defining associated parameters. 
The following table contains a description of each parameter 
available. 
 Figure 7.5
The Parameters tab is only available if you select the Original 
configuration.
Parameters Description
Scheme You can select the scheme type from the drop-down list.
Maximum 
Function 
Evaluation
Sets the maximum number of function evaluations (not to 
be confused with the maximum number of iterations). 
During each iteration, the relevant portion of the flowsheet 
is solved several times, depending on factors such as the 
Optimization Scheme, and number of primary variables.
Primary Variables are normalized.
Tolerance HYSYS determines the change in the objective function 
between iterations, as well as the changes in the 
normalized primary variables. Using this information, 
HYSYS determines if the specified tolerance is met.
Refer to Section 7.2.5 - 
Optimization Schemes 
for more information 
about the schemes.
xnorm
x xlow–
xhigh xlow–
---------------------------=7-9
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7-10 Original Optimizer
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ThMaximum 
Iteration
The maximum number of iterations. Calculations stop if the 
maximum number of iterations is reached.
All of the methods except the BOX method use derivatives.
Maximum 
Change/
Iteration
The maximum allowable change in the normalized primary 
variables between iterations. 
For instance, assume the maximum change per iteration is 
0.3 (this is the default value). If you have specified molar 
flow as a primary variable with range 0 to 200 kgmole/hr, 
then the maximum change in one iteration would be 
(200)(0.3) or 60 kgmole/hr.
Shift B ensures that the Shift interval xShift never be zero.
Shift A/ Shift 
B
Derivatives of the objective function and/or constraint 
functions with respect to the primary variables are 
generally required and are calculated using numerical 
differentiation.
The numerical derivative is calculated from the following 
relationship:
where: 
x = perturbed variable (normalized)
xshift = shift interval (normalized)
Derivatives are calculated using:
where: 
y2 = value of the affected variable corresponding to x 
+ xshift
y1 = value of the affected variable corresponding to x
Prior to each step, the Optimizer needs to determine the 
gradient of the optimization surface at the current location. 
The Optimizer moves each primary variable by a value of 
xshift (which due to the size of Shift A and Shift B be a very 
small step). The derivative is then evaluated for every 
function (Objective and Constraint) using the values for y 
at the two locations of x. From this information and the 
Optimizer history, the next step direction and size are 
chosen.
In general, it should not be necessary to change Shift A and 
Shift B from their defaults.
Some Schemes move all Primary variables simultaneously, 
while others move them sequentially.
Parameters Description
xshift ShiftA∗x ShiftB+=
∂y
∂x
-----
y2 y1–
xshift
---------------=7-10
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Optimizer Operation 7-11
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Th7.2.4 Monitor Tab
The Monitor tab displays the values of the objective function, 
primary variables, and constraint functions during the Optimizer 
calculations. New information is updated only when there is an 
improvement in the value of the Objective Function. The 
constraint values are positive if inequality constraints are 
satisfied and negative if inequality constraints are not satisfied. 
To determine each derivative, a variable evaluation must be 
made in addition to the main flowsheet evaluation which is 
done after each iteration (main step change). Therefore, if 
there are two primary variables, there are three function 
evaluations for every iteration.
If you have selected the Mixed Optimizer Scheme, the BOX 
and SQP methods are used in sequence - this is the reason 
why the Function Evaluations are reset part way through 
the calculations.
 Figure 7.6
The Monitor tab is only available if you select the Original 
configuration.
Parameters Description7-11
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7-12 Original Optimizer
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Th7.2.5 Optimization Schemes
The following sections describe the Optimization schemes for 
the Original Optimizer.
Function Setup
The Optimizer manipulates the values of a set of primary 
variables in order to minimize (or maximize) a user-defined 
objective function, constructed from any number of process 
variables.
where:  
x1,x2,...,xn = process variables
Each primary variable, x0, can be manipulated within a specified 
range: 
where:  
xi = a process variable used to define the Objective Function
 = a primary variable which is manipulated by the 
Optimizer
yi = a variable used to define the Constraint Function
(7.2)
In general, the primary variables should not be part of the 
Objective Function.
(7.3)
min f x1 x2 x3 ... xn, , , ,( )
xi  LowerBound
0 xi
0 xi  UpperBound
0    with  i< < 1 ... j, ,=
xi
0
7-12
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Optimizer Operation 7-13
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ThThe general equality and inequality constraints are:
The constraint functions should generally not use the primary 
variables.
All primary variables are normalized from the lower bound 
through the upper bound. Thus, reasonable lower and upper 
bounds must be specified. Exceedingly high or low variable 
bounds should obviously be avoided as they may result in 
numerical problems when scaling. An initial starting point must 
be specified, and it should be within the feasible region. 
Constraints are optional and are not supported by all of the 
Optimization Schemes.
If HYSYS fails to evaluate the objective function or any of the 
constraint functions, the Optimizer reduces the incremental step 
of the last primary variable by a half. The flowsheet is then 
recalculated. If the function evaluation is still unsuccessful, the 
optimization stops.
By default, the Optimizer is set up to minimize the objective 
function. A Maximize radio button is provided on the Functions 
tab if you want to maximize an objective function. Internally the 
Optimizer simply reverses the sign.
(7.4)
HYSYS recommends users to manually manipulate the 
primary variables to get a feel for the appropriate 
boundaries. Use the Data Recorder or Case Study tool for this 
purpose. 
ci y1 y2 y3 ... yn, , , ,( ) 0,= i 1 ... m1, ,=
ci y1 y2 y3 ... yn, , , ,( ) 0,≤ with i m1 1 ... m2, ,+=
ci y1 y2 y3 ... yn, , , ,( ) 0,≥ i m2 1 ... m, ,+=
Refer to Section 11.7 - 
Databook in the HYSYS 
User Guide.7-13
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7-14 Original Optimizer
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ThBOX Method
The procedure is loosely based on the “Complex” method of 
BOX1; the Downhill Simplex algorithm of Press et al2 and the 
BOX algorithm of Kuester and Mize.3
The BOX method is a sequential search technique which solves 
problems with non-linear objective functions, subject to non-
linear inequality constraints. No derivatives are required. It 
handles inequality constraints but not equality constraints. The 
BOX method is not very efficient in terms of the required 
number of function evaluations. It generally requires a large 
number of iterations to converge on the solution. However, if 
applicable, this method can be very robust.
Procedure:
1. Given a feasible starting point, the program generates an 
original “complex” of n+1 points around the centre of the 
feasible region (where n is the number of variables).
2. The objective function is evaluated at each point. The point 
having the highest function value is replaced by a point 
obtained by extrapolating through the face of the complex 
across from the high point (reflection).
3. If the new point is successful in reducing the objective 
function, HYSYS tries an additional extrapolation. Otherwise, 
if the new point is worse than the second highest point, 
HYSYS does a one-dimensional contraction.
4. If a point persists in giving high values, all points are 
contracted around the lowest point.
5. The new point must satisfy both the variable bounds and the 
inequality constraints. If it violated the bounds, it is brought 
to the bound. If it violated the constraints, the point is 
moved progressively towards the centroid of the remaining 
points until the constraints are satisfied.
6. Steps #2 through #5 are repeated until convergence.
The BOX Method only handles inequality constraints.7-14
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Optimizer Operation 7-15
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ThSQP Method
The Sequential Quadratic Programming (SQP) Method handles 
inequality and equality constraints.
SQP is considered by many to be the most efficient method for 
minimization with general linear and non-linear constraints, 
provided a reasonable initial point is used and the number of 
primary variables is small.
The implemented procedure is based entirely on the Harwell 
subroutines VF13 and VE174. The program follows closely the 
algorithm of Powell5.
It minimizes a quadratic approximation of the Lagrangian 
function subjected to linear approximations of the constraints. 
The second derivative matrix of the Lagrangian function is 
estimated automatically. A line search procedure utilizing the 
“watchdog” technique (Chamberlain and Powell6) is used to 
force convergence.
Mixed Method
The Mixed method attempts to take advantage of the global 
convergence characteristics of the BOX method and the 
efficiency of the SQP method. It starts the minimization with the 
BOX method using a very loose convergence tolerance (50 times 
the desired tolerance). After convergence, the SQP method is 
then used to locate the final solution using the desired 
tolerance.
The Mixed Method handles inequality constraints only.7-15
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7-16 Original Optimizer
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ThFletcher Reeves Method
The procedure implemented is the Polak-Ribiere modification of 
the Fletcher-Reeves conjugate gradient scheme. The approach 
closely follows that of Press et al2, with modifications to allow for 
lower and upper variable bounds. This method is efficient for 
general minimization with no constraints. 
The method used for the one-dimensional search can be found 
in reference 2, listed at the end of this chapter.
Procedure:
1. Given a starting point evaluate the derivatives of the 
objective function with respect to the primary variables.
2. Evaluate the new search direction as the conjugate to the old 
gradient.
3. Perform one-dimensional search along the new direction 
until the local minimum has been reached.
4. If any variable exceeds its bound, bring it back to the bound.
5. Repeat steps #1 through #4 until convergence.
Quasi-Newton Method
The Quasi-Newton method of Broyden-Fletcher-Goldfarb-
Shanno (BFGS) according to Press et al2 has been implemented. 
In terms of applicability and limitations, this method is similar to 
the of Fletcher-Reeves method.
The Fletcher Reeves (Conjugate Gradient) Method does not 
handle constraints.
The Quasi-Newton Method does not handle constraints.7-16
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Optimizer Operation 7-17
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ThThe Quasi-Newton method calculates the new search directions 
from approximations of the inverse of the Hessian Matrix.  
7.2.6 Optimizer Tips
The following are setup tips for the Original Optimizer.
1. Reasonable upper and lower variable bounds are extremely 
important. This is necessary not only to prevent bad 
flowsheet conditions (for example temperature crossovers in 
Heat Exchangers), but also because variables are scaled 
between zero and one in the optimization algorithms using 
these bounds. 
2. For the BOX and Mixed methods, the Maximum Change/
Iteration of the primary variables (set on the Parameters 
tab) should be reduced. A value of 0.05 or 0.1 is more 
appropriate.
3. The Mixed method generally requires the least number of 
function evaluations (in other words, is the most efficient).
4. If the BOX, Mixed or SQP Methods are not honouring your 
constraints, try increasing the Penalty Value on the 
Functions tab by 3 or 6 orders of magnitude (up to a value 
similar to the expected value of the objective function). In 
other words, it is helpful to attempt to get the magnitude of 
the objective function and penalty as similar as possible 
(especially when the BOX Method is used).
5. By default the Optimizer minimizes the objective function. 
You can maximize the objective function by selecting the 
Maximize radio button on the Functions tab. 
Method Unconstrained 
Problems
Constrained 
Problems: 
Inequality
Constrained 
Problems: 
Equality
Calculates 
Derivatives
BOX X X
Mixed X X X
SQP X X X X
Fletcher-Reeves X X
Quasi-Newton X X
Internally, the Optimizer multiplies the objective function by 
minus one for maximization.7-17
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7-18 Hyprotech SQP Optimizer
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Th7.3 Hyprotech SQP 
Optimizer
The Hyprotech SQP is a rigorous sequential quadratic 
programming (SQP) optimization solver. This solver features 
step size restriction, decision variable and objective function 
scaling, and a problem-independent and scale-independent 
relative convergence test. The algorithm also ensures that the 
model is evaluated only at points feasible with respect to the 
variable bounds.
To access the Hyprotech SQP Optimizer:
1. On the Configuration tab, select the Hyprotech SQP radio 
button in the Data Model group, as shown in the figure 
below:
2. The Hyprotech SQP Optimizer property view contains two 
tabs:
• Configuration
• Hyprotech SQP
The Hyprotech SQP requires the use of Derivative Utilities. 
 Figure 7.7
Refer to the Aspen RTO 
Reference Guide for 
details.
Refer to Section 7.1.2 - 
Configuration Tab for 
more information.7-18
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Optimizer Operation 7-19
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Th7.3.1 Hyprotech SQP Tab
The Hyprotech SQP tab allows you to manipulate the 
configuration Setup and Flags.
Setup Options
To access the Setup options, select Setup from the 
Configuration group on the Hyprotech SQP tab. The tab appears 
as shown in the following figure.
The Derivative Utilities group lists the derivative utilities that are 
run in the optimizer. To add or remove utilities from this list, 
click Select Utilities to Run and select the desired utilities.
The Starting Objective display field at the bottom right of the 
tab gives the objective function value at the starting point, 
before carrying out any optimization. The value is unscaled and 
you cannot change the value.
The parameters available in the Setup option are sorted into two 
groups:
• Setup
• Running Results
 Figure 7.87-19
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7-20 Hyprotech SQP Optimizer
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ThSetup Group
The Setup Group contains the following parameters:
Variables Description
Max. Iterations Specifies the maximum number of major iterations. A 
major iteration consists of a sequence of minor iterations 
that minimize a linearly constrained sub-problem. The 
default value is 50.
Objective Scale 
Factor
Specifies the factor used for scaling the objective 
function. Positive values are used as-is. Negative values 
use the factor abs(scale*F) (where F is the initial 
objective function value) and a factor is generated 
automatically for zero values. The default value is 1.0.
Gradient 
Calculations
Specifies what type of differences are being used when 
constructing gradient approximations. 1-sided causes 
forward differences to be used. 2-sided causes central 
differences to be used; it requires twice as many 
function evaluations at a given solution, but can provide 
a more accurate estimate of the constraint and objective 
gradients, particularly for highly non-linear problems or 
problems featuring large amounts of noise.
Diagnostic Print 
Level
Specifies the amount of information to include in the 
Optimizer diagnostic file. Options are None, Partial_1, 
Partial_2, Partial_3, Full, or Excessive. This file is 
created in the working Temp directory: C:\Documents 
and Settings\Username\Local Settings\Temp
Accuracy 
Tolerance
Specifies the relative accuracy tolerance used in the test 
for convergence. The following convergence test is used,
where:
The ConvergenceSum is a weighted sum of possible 
objective function improvement and constraint violations 
and has the same units as the objective function. This 
allows the same tolerance parameter to be used for 
different problems and makes the convergence test 
independent of objective function scaling. The default 
value is 10-4.
Step Restriction Specifies the line search step-size restriction factor used 
during the first 3 iterations. Values greater than 1.0 
result in no step restriction. Set the factor to 1.0, 10-1, 
10-2, and so forth, to impose larger restrictions. The 
default value is 0.2.
ConvergenceSum AccuracyTolerance max× F x( ) 1.0,( )≤
ConvergenceSum ∇F x( )rd ujCj x( )
j 1=
M
∑+=7-20
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Optimizer Operation 7-21
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ThRunning Results Group
You cannot change the values of the parameters in the Running 
Results group. The group contains the following parameters:
Perturbation Specifies the change in size of the scaled variables used 
in Gradient and Jacobian calculations. Individual 
variables are scaled according to the variable Minimum 
and Maximum properties The default value is 10-3.
Max. Feasible 
Point
Specifies the maximum number of iterations allowed in 
the line search procedure of Hyprotech SQP. When the 
maximum feasible point iterations are reached, the 
solver terminates and displays an error message of Step 
Convergence, meaning that the required optimization 
accuracy cannot be achieved. If this error occurs very 
early in the calculation, the initial values of the 
optimization variables might be inappropriate.
Variables Description
Objective Value Displays the current plant model objective function 
value as calculated by the Optimizer.
Termination 
Reason
Displays the termination status of the Optimizer. 
Values include Running, Step convergence, 
Unbounded, Impossible, Not run, and Stopped.
Actual Optimizer Displays the number of major iterations.
Feasible Point 
Iterations
Displays the number of minor iterations since the last 
major iteration.
Total CPU Time Reports the time taken to solve the optimization 
problem.
Solution Phase Displays the current phase of the Optimizer algorithm. 
Values include Initialize, Setup, OPT Deriv, OPT Search, 
and Results.
Gradient 
Evaluations
Reports the number of gradient evaluations performed 
during the course of the optimization.
Model 
Evaluations
Reports the number of model evaluations performed 
during the course of the optimization.
Code Version The version of Optimizer.
Variables Description7-21
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7-22 Hyprotech SQP Optimizer
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ThResults
The results produced at the end of the optimization run are as 
follows:
• Values of the Optimizer constraints, variables, and 
objective function.
• Shadow prices for active constraints.
• A termination reason.
• Iterations and CPU time taken.
Some of the above mentioned results can be seen in the 
Running Results group, and the other results are found in the 
Derivative utilities.
Flags Option
If you select the Flags radio button from the Configuration 
group, the Hyprotech SQP tab appears as shown in the figure 
below.
 Figure 7.97-22
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Optimizer Operation 7-23
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ThThe following table explains the options available in Flags group:
7.4 MDC Optim
This option gives you access to MDC Optim optimization solver. 
This option is only available with a HYSYS.RTO license. For more 
information on this solver, refer to the Optimizer section in the 
Aspen HYSYS.RTO Reference Guide.
Options Description
Omit. Tech 
Constraints
Not used.
Relax Violated 
Constraints
Not used.
Include Fixed 
Constraints
If this checkbox is selected, then the Optimizer 
variables that have their Optimize Flag property 
checkbox selected are included in the optimization 
even if they have equal Minimum and Maximum 
values.
Numerical 
Gradients
Not used.
Hyprotech SQP 
Calc Gradients
If this flag is checked when the Hyprotech SQP solver 
is used, then the Hyprotech SQP algorithm itself carries 
out numerical calculation of any gradient elements 
needed.
Include Variable 
Scales
Includes the variable Range properties as scaling 
factors within the algorithm.
Reset Perts. Used at the start of optimization to indicate that the 
gradient calculation process removes noise elements 
(activated) or not (deactivated).
Use NN for 
Optimization
Allows you to use any trained Neural Network in the 
flowsheet to replace the traditional HYSYS solver for 
optimization. This improves the robustness of the 
model, and reduces the calculation time thereby 
improving overall performance. However, the accuracy 
in the solution depends upon how the NN is trained and 
the data available. Upon solving the NN’s are 
unembedded and the flowsheet solves at the optimizer 
given values. 
Use NN for 
Jacobian
Allows you to use any trained Neural Network to 
calculate the Jacobian. This is used to determine the 
next step in the Optimization process. This is slower 
than the above option but is more accurate. See 
Optimization above for more details.
Refer to Section 14.14 - 
Parametric Utility for 
more details on NN’s.7-23
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7-24 DataRecon
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Th7.5 DataRecon
The DataRecon object access the Data Reconciliation Utility. For 
more information on this utility, refer to the Data 
Reconciliation Utility section of the Utilities chapter of this 
manual.
7.6 Selection Optimization
The Selection Optimization consists of algorithms that solve 
Mixed Integer Non-Linear Programming (MINLP) problems, in 
which the objective function is minimized by adjusting both the 
real-valued decision variables, and binary-valued decision 
variables. These binary, or discrete state variables can be used 
to represent the state of the equipment (On, Off, Out of Service, 
and Always in Service) in the Derivative Utility. The algorithms 
attempts to select a combination of discrete states that both 
satisfy the constraints, and minimize the objective function. 
There are two MINLP methods available: Stochastic (also known 
as the simulated annealing method), and Branch and Bound. 
These methods use Non-Linear Programming (NLP) optimizers 
(Hyprotech SQP, and MDC Optim) to solve sub-problems.
To access the Selection Optimization:
1. On the Configuration tab, select the Selection 
Optimization radio button in the Data Model group.
2. Click on the Selection Optimization tab.
7.6.1 Selection Optimization 
Tab
The Selection Optimization tab allows you to select, and 
configure the type of discrete solver, and non-linear optimizer. 
Two base groups are available on the Selection Optimization 
tab:7-24
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Optimizer Operation 7-25
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Th• Discrete Solver Options. You can select the Stochastic, 
or Branch and Bound solver by clicking on the 
appropriate radio button. Depending on the type of 
discrete solver you selected, additional groups appear on 
the Selection Optimization tab.
• Non Linear Optimization Configuration. There are 
two non- linear optimizers available: Hyprotech SQP, and 
MDC Optim. You can select the type of non-linear 
optimizer by clicking on the appropriate radio button. 
Depending on the type of non-linear optimizer you 
selected, additional tabs appear on the Optimizer 
property view for further configuration.
The following sections describe the Stochastic, and Branch and 
Bound discrete solving methods.
Stochastic Method
The Stochastic method is a simulated annealing algorithm, 
which is derived from the statistical mechanics for finding near 
globally optimum solutions in non-linear integer problems. 
The algorithm is based on the analogy between the annealing of 
solids, and combinatorial optimization. The analogies are as 
follows:
• The states of the solids in annealing represent the 
feasible solutions of the optimization problem.
• The energies of state in annealing correspond to the 
value of the objective function.
• The minimum energy state in annealing corresponds to 
the optimum solution.
• Rapid quenching (fast cooling) corresponds to local 
optimum in the optimization problem.
At a given temperature, the probability distribution of the 
system energies is determined by the Boltzmann function:
where:  
E = System energy
(7.5)
 
For more information, 
refer to Hyprotech SQP 
Optimizer (Section 7.3 - 
Hyprotech SQP 
Optimizer), and MDC 
Optimizer (Chapter 5 - 
DRU Overview in the 
Aspen RTO Reference 
Guide).
P E( ) e E kT( )⁄–∝7-25
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7-26 Selection Optimization
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Thk = Boltzmann constant
T = Temperature
P(E) = Probability of the system in a state with E energy
The simulated annealing algorithm implemented in the 
Stochastic method uses a criterion similar to the Boltzmann 
probability function. The criterion states that if the difference 
between the objective function values of the current and the 
newly produced solution is equal to or larger than zero, a 
random number, ,with uniform distribution [0,1] is generated. 
If the random number satisfy the following condition:
then the newly produced solution is accepted as the current 
solution; else the current solution is unchanged.
Once a state (set of discrete variables) is selected based on the 
above criterion, the solution to the problem is obtained by using 
non-linear optimization.
The Stochastic method consists of two groups:
• Stochastic Parameters
• Stochastic Optimization Output
Stochastic Parameters Group
The Stochastic Parameters consists of three parameters:
(7.6)
 Figure 7.10
∂
∂ e EΔ T⁄–≤7-26
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Optimizer Operation 7-27
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ThStochastic Optimization Output Group
In the Stochastic Optimization Output group, you can view the 
Best Objective Function value in the optimization based on the 
parameters specified in the Stochastic Parameters group.
Branch and Bound Method
The Branch and Bound method first solves the original MINLP 
problem as a NLP problem by relaxing the integer restrictions, 
so that the calculations can converge with a less tight integer 
tolerance. The method continues by performing a systematic 
search of continuous solutions (called nodes), in which the 
integer variables are successively forced to take on integer 
values. This process is known as branching. The structure of this 
set of problems takes on the form of a tree. The procedure of 
branching, and solving a sequence of continuous problems is 
continued until a feasible integer solution is found. The value of 
the objective function becomes an upper bound of the objective 
Parameter Description
No Of 
Iterations
Allows you to specify the number of iteration in the 
simulated annealing algorithm. The number of iteration is a 
hard limit which means that the algorithm stops when the 
specified number of iteration is reached.
By default, the No Of Iterations is set to 10.
Time Limit Allows you to specify the algorithm time constraint (in 
minute). Once the Time Limit value is reached, the 
algorithm completes the move that it is solving.
By default, the Time Limit is set at 2.
Annealing 
Temperature
Allows you to specify the temperature that is used to 
control the progression of the optimization problem toward 
an optimum solution. As a general rule, the Annealing 
Temperature should be the same order of magnitude of the 
Best Objective Function.
By default, the Annealing Temperature is set to 1.000e-
003.
 Figure 7.117-27
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7-28 Selection Optimization
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Thof the MINLP problem. At this point, all of the continuous 
solutions whose objective function values are higher than the 
upper bound are eliminated from consideration. This elimination 
process is known as fathomed. Nodes are fathomed when the 
continuous problem is infeasible or when it has a natural integer 
solution. The search for the optimal solution terminates when all 
nodes are fathomed.
The Branch and Bound method contains two main groups:
• Branch and Bound Parameters
• Branch and Bound Output
Branch and Bound Parameters
The Branch and Bound Parameters group consists of five sub 
groups:
• Branching
• Node Selection
• Convergence
• Bluff
• Search
 Figure 7.127-28
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Optimizer Operation 7-29
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ThBranching
The Branching group contains the following parameters:
Node Selection
A node is explicitly or implicitly fathomed when it satisfies one of 
the following conditions:
• when the solution is an integer value
• when the solution is infeasible
• when the optimal value is higher than the current upper 
bound
 Figure 7.13
Parameters Description
Order Allows you to specify the method for selecting the 
branching variable. You can select the type of Order from 
the Order drop-down list:
• Fractional. Selects the most fractional binary 
variable.
• Fixed. Selects the variable by using the binary 
variable parameter rank.
By default, the Order is set to Fractional.
Search Allows you to indicate whether a branch-and-bound search 
is to be performed after the solution of the relaxed problem 
is found. By default, the Search is set to Yes.
 Figure 7.147-29
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7-30 Selection Optimization
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ThThe Node Selection group contains the following parameters:
Convergence
The Convergence group allows you to specify the integer 
restrictions and convergence conditions. 
The Convergence group contains the following parameters:
Parameters Description
Select Allows you to specify the method of node selection:
• Best Bound. Selects the node with the lowest 
objective function value.
• Dive. Selects the most recent node for branching.
By default, Best Bound method is selected.
Maximum Allows you to specify the maximum number of nodes to be 
searched (excluding relaxing and heuristic problems). The 
Maximum must be equal or larger than 1, and by default, it 
is set to 10.
 Figure 7.15
Parameters Description
Absolute Allows you to specify the absolute convergence tolerance. 
The tolerance is compared with the absolute difference 
between the upper and lower bounds on the objective 
function. By default, the Absolute is set to 0.0.
Relative Allows you to specify the relative convergence tolerance. 
The tolerance is compared with the relative difference 
between the upper and lower bounds on the objective 
function. The Relative value must be within the range of 0.0 
to 1.0. By default, the Relative is set to 0.1.
Integer 
Tolerance
Allows you to specify the tolerance used when testing 
whether a relaxed binary variable is considered to be 
binary-valued (in other words, 0 or 1). The Integer 
Tolerance must be in between 0.0 to 0.5. By default, the 
Integer Tolerance is set to 1.0e-4.7-30
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Optimizer Operation 7-31
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ThSearch
The Search group contains the following parameters:
Initialization Allows you to specify the method of initializing optimization 
variables prior to the solution of each sub-problem. You can 
select one of following options from the Initialization drop-
down list:
• Current. Does not perform any re-initialization. In 
other words, variable values start with the values they 
had at the end of the previous sub-problem.
• Initial. Sets variables to the values that they had 
when the algorithm was started.
• Relaxed. Sets the variables to the optimal values 
found for the relaxed sub-problems.
By default, the Initialization option is set to Current.
Time limit 
(min)
Allows you to specify a time limit (in minutes) for the 
search procedure. The Time limit is used in addition to the 
maximum number of nodes to place a limit on the length of 
the search. The Time limit value must be greater than 0.0. 
By default, the Time limit field is .
 Figure 7.16
Parameters Description7-31
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7-32 Selection Optimization
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ThBluff
There are three parameters in the Bluff group:
• Gap. Provides an estimate of the relative gap between 
the objective function values of the relaxed problem, and 
optimal integer solution. The algorithm computes an 
upper bound on the objective function value after the 
solution of the relaxed problem. This is used to eliminate 
nodes in the search tree whose objective functions are 
not better than the Incumbent. The Incumbent objective 
function FI is calculated from the fully relaxed objective 
FR, and the Gap is defined as:
Parameters Description
Quit Allows you to end (Yes) or continue (No) the search when 
an improved integer solution over the Incumbent is found. 
By default, the Quit option is set to No.
Quit 
Tolerance
The Quit Tolerance provides the relative amount of 
improvement required in an integer solution to end the 
search. This parameter only has an effect if the Quit option 
is selected as Yes. The relative improvement in the 
Incumbent is defined as:
where:
FI = Objective function of the incumbent
fI = Objective function of the improved integer 
solution
If the Quit Tolerance field is specified as 0.0 or left empty, 
finding any improvement will end the search. By default, 
the Quit Tolerance is . You can only specify the 
Quit Tolerance value equal to or greater than 0.0.
 Figure 7.17
(7.7)
FI fI–( )
FI
-------------------
FI FR Gap 1.0 FR+( )⋅+=7-32
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Optimizer Operation 7-33
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ThThe branch-and-bound search will fail if the Gap value is 
too small. By default, the Gap field is . The Gap 
value must be greater than 0, and it is recommended to 
set it to 0.25.
• Incumbent. The objective function value of the best 
binary-valued solution known so far. The value is used to 
eliminate nodes in the search that are not better than the 
Incumbent value. A value given for the Incumbent will 
override the value generated by using the Gap value. By 
default, the Incumbent field is .
• Heuristic. Allows you to specify the type of heuristic 
algorithm for finding an initial integer-feasible solution 
that is used to update the objective function Incumbent 
value. There are two types of Heuristic:
- Initial. Uses initial State Variable values.
- Round. Round the values of the State Variables.
Branch and Bound Output
The Branch and Bound Output group contains the following 
fields for displaying the optimization results:
By default, the Heuristic type is set to None. It is 
recommended that the type to be set to Initial.
 Figure 7.18
Parameters Description
Relaxed Obj. Value of the objective function for the fully relaxed 
problem.
Incumbent 
Obj.
Value of the Incumbent objective function. The Incumbent 
is the lowest objective function of an integer-valued 
solution. This value is initialized by using the user-specified 
Incumbent and Gap parameters. The Incumbent Obj value 
is updated throughout the branch and bound search.
Current Node The node of the branch and bound tree currently being 
solved. A number of 0 indicates that it is a fully relaxed 
problem.7-33
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7-34 Selection Optimization
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Th7.6.2 Selection Optimization 
Tips
The following are setup tips for the Selection Optimization:
1. Since the algorithm used in the Stochastic method moves all 
over the solution space, the higher the number of iterations 
that the algorithm performs, the higher the probability there 
will be for finding a global optimum solution.
2. In the Branch and Bound method, reasonable convergence 
criteria, for example, value of Relative is important. It is 
recommended that you should accept the solution if an 
integer-feasible solution can be found during the search that 
has an objective function close to that of the fully relaxed 
solution.
3. In the Branch and Bound method, use Gap or Incumbent to 
reduce the size of the search space. Be aware that too much 
bluffing (for example a small value of Gap) can eliminate 
large sections of the search tree, resulting in a failed or sub-
optimal search.
4. It is important to specify a Heuristic type in Branch and 
Bound method, especially if the Gap or Incumbent have not 
been specified. If the Heuristic successfully finds an integer-
feasible solution, the objective function value can be used to 
eliminate sections of the search region. The Heuristic can 
satisfy the convergence criteria.7-34
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Optimizer Operation 7-35
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Th7.7 Example: Original 
Optimizer
Create the following sample case of multiple heat exchangers to 
optimize the overall UA by using the Original Optimizer.
PFD
Using the Peng Robinson property package and the listed 
components specify the process streams outlined in the 
following table.
Inlet Process Streams 
 Figure 7.19
Material Streams
Tab [Page] In this cell... Feed E-100 Cool 
In
Valve In E-102 Cool 
In
Worksheet 
[Conditions]
Temperature (F) 20 -142 120 
Pressure (psia) 1000 250 350 251
Molar Flow (lbmole/hr) 2745 1542  16407-35
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7-36 Example: Original Optimizer
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ThProcess Operations
A tee, mixer, valve, and three heat exchangers are required for 
this process. Enter the data as shown in the figures below.
• TEE-100
Worksheet 
[Composition]
Methane Mole Frac 0.7515 0.9073 0.0000 0.2828
Ethane Mole Frac 0.2004 0.0927 0.0000 0.2930
Propane Mole Frac 0.0401 0.0000 1.0000 0.1414
i-Butane Mole Frac 0.0040 0.0000 0.0000 0.1313
n-Butane Mole Frac 0.0040 0.0000 0.0000 0.1515
Material Streams
Tab [Page] In this cell... Feed E-100 Cool 
In
Valve In E-102 Cool 
In
 Figure 7.207-36
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Optimizer Operation 7-37
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Th• MIX-100
• VLV-100
 Figure 7.21
 Figure 7.227-37
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7-38 Example: Original Optimizer
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Th• Heat Exchanger E-100
• Heat Exchanger E-101 
 Figure 7.23
Heat Exchanger [E-100]
Tab [Page] In this cell... Enter
Design 
[Parameters]
Tubeside Delta P 10 psi
Shellside Delta P 10 psi
UA 4.00e+04 Btu/F-hr
Heat Leak/Loss None
Heat Exchange Model Weighted
Intervals (E-100 Feed) 10
Intervals (E-100 Cool In) 10
Dew/Bubble Pt (E-100 Cool In) Inactive
 Figure 7.247-38
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Optimizer Operation 7-39
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Th• Heat Exchanger E-102
Heat Exchanger [E-101]
Tab [Page] In this cell... Enter
Design 
[Parameters]
Tubeside Delta P 5 psi
Shellside Delta P 1 psi
UA 5.00e+04 Btu/F-hr
Heat Leak/Loss None
Heat Exchange Model Weighted
Intervals (E-100 Feed) 10
Intervals (E-100 Cool In) 10
 Figure 7.25
Heat Exchanger [E-102]
Tab [Page] In this cell... Enter
Design 
[Parameters]
Tubeside Delta P 5 psi
Shellside Delta P 5 psi
UA 3.50e+04 Btu/F-hr
Heat Leak/Loss None
Heat Exchange Model Weighted
Intervals (E-100 Feed) 10
Intervals (E-100 Cool In) 10
Dew/Bubble Pt (E-102 Cool In) Inactive7-39
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7-40 Example: Original Optimizer
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ThStream Specifications
• Temperature of stream E-102 Out, -40°F
• Vapour Fraction stream E-101 Cool Out, 1.00
• Temperature of stream E-100 Out, -65°F
• Pressure of E-101 Cool Out, 20 psia
Results
The calculated streams are shown in the figure below.
7.7.1 Optimizing Overall UA
The Optimizer determines the optimum Tee flow ratio such that 
the Overall UA is minimized. Therefore, delete the individual 
heat exchanger UA specs and replace them with the following:
• Temperature of E-102 Cool In = -85°F
• Flowrate of Valve In = 495 lbmole/hr
• Flowrate of E-101 Feed = Optimized variable (Initially set 
to the previous flow rate of 1,670 lbmole/hr)
After replacing the specs, the flowsheet solves and UAs are 
calculated.
 Figure 7.267-40
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Optimizer Operation 7-41
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ThOpening the Optimizer
To open the Optimizer:
1. Click the Add button in the Variables tab to display the 
Variable Navigator.
2. Select the Molar Flow of the stream E-101 Feed.
3. Specify the Low and High Bounds as shown in the figure 
below.
The search is now within a range of 1450 lbmole/hr - 1800 
lbmole/hr to avoid a temperature cross.
Import the Heat Exchanger
To import the three Heat Exchanger UAs to the Optimizer 
spreadsheet:
1. Click the SpreadSheet button to display the Optimizer 
Spreadsheet property view.
2. Click the Connections tab and then click the Add Import 
button to display the Variable Navigator property view.
3. Import the UA value for the heat exchanger E-100.
 Figure 7.277-41
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7-42 Example: Original Optimizer
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Th4. Repeat steps#2 and#3 for the Heat Exchangers E-101 and 
E-102.
5. Click the Spreadsheet tab. In cell A4, enter the formula, 
+a1+a2+a3. This sums the UAs. In cell A5, enter 0.0. This 
is used in the constraints.
6. Close the Optimizer Spreadsheet property view.
Defining the Objective Function
You must define the Objective Function and the Constraint 
Functions. The Objective Function is the expression being 
minimized, which in this case is the sum of the Heat Exchanger 
UAs.
1. Click the Functions tab in the Optimizer property view.
2. Click the Cell drop-down list and select A4. The value of the 
cell is displayed in the Current Value field.
3. Click the Minimize radio button.
 Figure 7.287-42
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Optimizer Operation 7-43
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ThAdding Constraint Functions
Enter constraint functions to ensure the solution is reasonable. 
Each Heat Exchanger UA must be greater than zero.
1. Click the Add button three times to add three constraints to 
the table.
2. In the LHS Cell drop-down list, select the cell A1, A2, and A3 
for each of the respective constraints.
3. In the RHS Cell drop-down list, select the cell A5 for each of 
the constraints.
4. Click the Parameters tab. For this example, use the Mixed 
method leaving all the parameters at their defaults.
5. Click the Start button, and then click the Monitor tab to 
watch the progress of the Optimizer.
An optimum molar flow of 1,800 lbmole/hr is obtained for the 
stream E-101 Feed, corresponding to an overall UA of about 
1.43e5 Btu/F-hr. This compares to the specified value of 1.5e5 
Btu/F-hr in the first part of this example.
 Figure 7.297-43
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7-44 Example: MNLP Optimization
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Th7.8 Example: MNLP 
Optimization
In this example, the Hyprotech SQP Optimizer is used with 
Selection Optimization to determine the most economical use of 
each boiler in a steam utility system to meet the steam demand.
Create the following steam utility system in Steady-State.
PFD
The steam demand is supplied by using three parallel boilers 
connected to a common high-pressure header. The boilers are 
modeled as simple heaters, each with different capacity, fuel 
cost, overhead cost, and efficiency. The high-pressure header is 
modeled by using a tee unit operation.
 Figure 7.307-44
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Optimizer Operation 7-45
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ThDefining the Simulation Basis
1. In the Simulation Basis Manager, define the property 
package as NBS Steam, and specify water (H2O) as the 
component.
2. Specify the Feed stream as follows:
3. Specify the mass flowrate for the following boiler inlet 
streams:
The mass flowrate of B1 IN is 5,400 kg/h, which is automatically 
calculated by HYSYS after you have defined B2 IN and B3 IN.
4. Specify a temperature of 350°C (662°F) for all three boilers 
outlet streams (B1 OUT, B2 OUT, and B3 OUT).
5. Specify a pressure drop of 0 kPa for each boiler.
The steam utility system is now fully defined. The results of each 
stream are summarized in the Workbook as shown below:
In this cell... Enter...
Temperature 21.3°C (70.3°F)
Pressure 4,101.3 kPa (594.8 psia)
Mass Flow 14,400 kg/h (31746 lb/hr)
Mass Fraction (H2O) 1
Stream Mass Flowrate
B2 IN 3,600 kg/h (7937 lb/hr)
B3 IN 5,400 kg/h (11905 lb/hr)
 Figure 7.31
Refer to Section 5.2 - 
Simulation Basis 
Manager in the HYSYS 
User Guide for more 
information on selecting a 
property package, and 
adding components.7-45
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7-46 Example: MNLP Optimization
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ThHeat Flow & Costs Calculations
Before the case is converted into an optimization problem, the 
efficiency, actual heat flow, and operating cost for each boiler 
are calculated within the Spreadsheet operation.
Add a Spreadsheet operation to the case and name it to Boilers 
Calculations.
Efficiency
The efficiency of the three boilers are locally characterized by 
the following relationship:
where:  
Eff = Efficiency of the boiler
EffMAX = Maximum efficiency of the boiler
Flow = Inlet mass flowrate of the boiler
FlowMAX = Inlet mass flowrate of the boiler at maximum 
efficiency
FlowMAX-5% = Inlet mass flowrate at an efficiency 5% less 
than the maximum efficiency.
The squared term in Equation (7.8) is a scaled deviation in 
flowrate with respect to the mass flow which gives the 
maximum efficiency.
(7.8)
The quadratic approximation between the steam mass 
flowrate, and boiler efficiency is valid only within a narrow 
range of operation, localized near the point of maximum 
efficiency.
Refer to Section 5.10 - 
Spreadsheet for more 
information on the 
Spreadsheet operation.
Eff EffMAX 5%
Flow FlowMAX–
FlowMAX 5%– FlowMAX–
-------------------------------------------------------------⎝ ⎠
⎛ ⎞
2
×–=7-46
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Optimizer Operation 7-47
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ThThe following table lists the efficiency parameters associated 
with each boiler:
Calculate the efficiency of each boiler in the Boilers Calculations 
spreadsheet. The following efficiency results should appear on 
the Spreadsheet:
Actual Heat Flow
The heat flow values calculated in HYSYS are the heat flow 
required by each boiler when the boiler is operating at the 
efficiency calculated from Equation (7.8). Therefore, the actual 
heat flow is calculated with the following equation:
where:  
Heat Flow = Heat flow of the boiler calculated in HYSYS
Eff = Efficiency of the boiler (see Equation (7.8))
Parameters B1 B2 B3
EffMAX 85% 87% 90%
FlowMAX 1.8 kg/s 2.2 kg/2 1.6 kg/s
FlowMAX-5% 3.0 kg/s 3.8 kg/s 2.5 kg/s
 Figure 7.32
(7.9)Actual Heat Flow Heat Flow 100
Eff
--------×=7-47
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7-48 Example: MNLP Optimization
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ThThe calculated efficiencies are used to calculate the Actual Heat 
Flow required by each boiler. The following results should appear 
on the Boilers Calculations spreadsheet:
Cost Calculations
The objective of this optimization problem is to minimize the 
total operating cost of the system, which is defined as the 
additive operating costs of each boiler:
where:  
i = Boiler i
The operating cost for each boiler is the sum of the fuel 
consumption cost, and overhead cost associated with the 
operation. The fuel cost, and the overhead cost of each boiler 
are listed in the following table:
 Figure 7.33
(7.10)
Cost B1 B2 B3
Fuel ($/MJ) 0.008 0.0085 0.0088
Overhead ($/hr) 30 29 25
Total Operating Cost (Operating Cost)∑ i
=
7-48
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Optimizer Operation 7-49
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ThSince the overhead cost only applies when the boiler is 
operating, the overhead cost is multiplied to a binary state 
variable of 1 or 0; a value of 1 indicates an ‘on’ status, and 0 
reflects a ‘off’ status. The operating cost for each boiler is 
defined as follows:
where:  
Status = Binary state variable of the boiler (1 = on, 0 = off)
To specify an ‘on’ status for all three boilers in the Boilers 
Calculations spreadsheet:
1. Create a new column called Status.
2. Specify a value of 1 in three spreadsheet cells under the 
Status column to represent the state of the three boilers.
For now, it is assumed that all three boilers are in operation. 
Therefore the overhead cost applies to all three boilers. During 
optimization, the Status of each boiler changes accordingly to 
obtain the minimum objective function.
The following operating cost for each boiler should appear on 
the Boilers Calculations spreadsheet:
(7.11)
 Figure 7.34
Operating Cost
Actual Heat
Flow⎝ ⎠
⎛ ⎞ Fuel
Cost⎝ ⎠
⎛ ⎞ Overhead
Cost⎝ ⎠
⎛ ⎞+× Status×=7-49
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7-50 Example: MNLP Optimization
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Th7.8.1 NLP Setup
Defining the Optimizer
1. Select Optimizer from the Simulation menu. The 
Optimizer property view appears.
2. In the Optimizer property view, select the Hyprotech SQP 
radio button on the Configuration tab. 
3. Click on the Hyprotech SQP tab.
4. In the Configuration group, click on the Setup radio button.
5. In the Setup group, set the Accuracy Tolerance to 1.00e-
006, and set the Perturbation to 1.00e-004.
6. Close the Optimizer property view.
Adding the Derivative Utility
1. Select Utilities from the Tools menu.
2. Select Derivative Utilities.
3. Click the Add Utility button to add a Derivative Utility. The 
Derivative Utility property view appears.
 Figure 7.35
Refer to Section 7.3 - 
Hyprotech SQP 
Optimizer for more 
information on Accuracy 
Tolerance and 
Perturbation.
Refer to Section 7.26 - 
Utilities in the HYSYS 
User Guide for more 
information on Utilities.7-50
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Optimizer Operation 7-51
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ThDefining the Object Filter
1. Click on the Configuration tab in the Derivative Utility 
property view.
2. In the Derivative Utility Configuration group, click on the 
Operation button. The Target Objects property view 
appears.
 Figure 7.36
 Figure 7.377-51
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7-52 Example: MNLP Optimization
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Th3. Click on the Flowsheet Wide radio button in the Object 
Filter Group.
4. Select FlowsheetWide in the Flowsheet Wide group.
5. Click the Transfer icon to transfer FlowsheetWide to the 
Scope Objects group.
6. Click the Accept List button in the Scope Objects group to 
save the setting. The Target Objects property view closes.
Defining the Optimization Variables
1. In the Derivative Utility property view, click on the 
Variables tab.
2. In the Variables tree browser, select the Variables branch.
3. Click on the Plus icon  to expand the Variables branch.
4. Select the Config. sub branch.
5. In the Derivative Utility Configuration group, select OptVars 
from the Add drop-down list.
6. Click on the Add button. The Select optimization variables 
and DCS Tags property view appears.
7. Select B2 IN from the Object list.
8. Select Mass Flow from the Variable list.
9. Click OK.
The mass flowrate of B2 IN is added to the Variables Config 
table on the Variables tab in the Derivative Utility property 
view.
 Figure 7.38
Transfer icon
Variables tree browser7-52
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Optimizer Operation 7-53
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Th10.Rename the Object Name to B2 IN as shown below:
11.Click on the Input sub branch under the Variables branch in 
the Variables group.
12. In the Variables Input table, set the Minimum, and Maximum 
of B2 IN to 0, and 36,000 kg/h, respectively.
13.Repeat step 2 to 12 for B3 IN.
Defining the Objective Function
1. In the Derivative Utility property view, click on the 
Constraints/Objective Functions tab.
2. In the Dependent tree browser, select the Objective Function 
branch.
3. In the Derivative Utility Configuration group, select ObjFunc 
from the Add drop-down list.
4. Click the Add button. The Select optimization variables and 
DCS Tags property view appears.
5. Select Boilers Calculations as the Object.
6. From the Variable list, select the cell where you calculated 
the total operating costs of all three boilers.
7. Click OK.
The Total Operating Cost value appears in the Objective 
Function table on the Constraints/Objective Function tab.
8. Set the Price to 1.
9. Change the Object Name to Total Cost as shown below.
 Figure 7.39
 Figure 7.40
Dependent tree browser7-53
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7-54 Example: MNLP Optimization
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ThDefining the Process Constraints
1. In the Derivative Utility property view, click on the 
Constraints/Objective Function tab.
2. Expand the Process Constraints branch from the Dependent 
tree browser.
3. Select the Config. sub branch.
4. In the Derivative Utility Configuration group, select 
ProcCons from the Add drop-down list.
5. Click the Add button.
6. Select the Boilers Calculations spreadsheet from the 
Variable list.
7. From the Object List, select the cell where you calculated the 
actual heat flow for boiler 1.
8. Click OK.
9. In the Process Constraint Config table, change the Object 
Name of the newly added process constraint to Q1 as shown 
below:
10. In the Dependent group, select the Input sub branch under 
the Process Constraints branch.
11.Set the Scale to 1.
12.Specify a Minimum of 0 and Maximum of 12,500 kW as show 
below:
13.Select the Use Flag checkbox.
The Use Flag checkbox allows you to eliminate evaluation of 
infeasible integer candidate. You can reduce the amount of 
time for the optimization calculation by selecting the 
appropriate variables.
 Figure 7.41
 Figure 7.42
Dependent tree browser7-54
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Optimizer Operation 7-55
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Th14.Add a series of process constraints as shown in the table 
below by repeating step 2 to 13 for each constraint.
7.8.2 MINLP Setup
Defining Slack Variables
Three slack variables are added to the Boilers Calculations 
spreadsheet to represent the maximum flow constraints on the 
inlet mass flowrate of each boiler. The slack variable is defined 
as follows:
where:  
SlackMAX = Maximum slack value
Flow = Inlet mass flowrate of the boiler
FlowMAX = Maximum inlet mass flowrate of the boiler (36,000 
kg/h)
1. Calculate the slack values for the three boilers. 
The following slack values should appear in the Boilers 
Calculations spreadsheet:
Variable Object
Object 
Name
Minimum Maximum
B2 Heat Flow Q2 0 kW 9,500 kW
B3 Heat Flow Q3 0 kW 13,500 kW
B1 IN Mass Flow B1 IN 0 kg/s 10 kg/s
B2 IN Mass Flow B2 IN 0 kg/s 10 kg/s
B3 IN Mass Flow B3 IN 0 kg/s 10 kg/s
(7.12)
 Figure 7.43
SlackMAX Flow= FlowMAX– Status×7-55
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7-56 Example: MNLP Optimization
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Th2. Add the slack values from the Boilers Calculations 
spreadsheet to the Derivative Utility as process constraints.
3. In the Derivative Utility, set the Maximum of each slack 
variable to 0.
4. Set the Minimum to a superfluous value of -1.00e+006.
5. Rename the slack values as Slack Max B1, Slack Max B2, 
and Slack Max B3 for the appropriate boiler
6. Select the Use Flag checkbox for all slack variables.
The Process Constraints table should contain all the constraints 
as shown in the following figure:
Defining the State Variables
Define three state variables in the Derivative Utility to reference 
the three binary equipment states from the Boilers Calculations 
spreadsheet.
To add the state variables in the Derivative Utility:
1. In the Derivative Utility property view, click on the 
Variables tab.
2. In the Variables group, select the State Variable branch.
3. Select StateVars from the Add drop-down list in the 
Derivative Utility Configuration group.
4. Click Add.
5. Select Boilers Calculations as the Object.
6. From the Object List, select the cell where you specified the 
binary state variable for Boiler 1.
7. Click OK.
8. Rename the newly added state variable to Use B1.
 Figure 7.44
Refer to the section on 
Defining the Process 
Constraints for more 
information on adding 
process constraints in the 
Derivative Utility.7-56
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Optimizer Operation 7-57
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Th9. Repeat step 3 to 8 for Boiler 2, and Boiler 3.
The State Variables table should appear as follows:
10.Click the Close button to close the Derivative Utility property 
view.
Defining the Selection Optimization
The final step is to define the Selection Optimization 
requirements.
1. Select Optimizer from the Simulation menu.
2. Click on the Selection Optimization radio button.
3. Click on the Selection Optimization tab.
4. Click on the Stochastic radio button in the Discrete Solver 
Options group.
5. In the Stochastic Parameters group, set the Time Limit (min) 
to 5.
6. Set the Annealing Temperature to 100.
7. Click the Start button.
Optimization Results
The lowest cost (best objective function value) is displayed in 
the Stochastic Optimization Output Group on the Selection 
Optimization tab of the Optimizer property view:
 Figure 7.45
 Figure 7.467-57
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7-58 Example: MNLP Optimization
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ThThe flow, and operating conditions of each boiler required to 
achieve the best objective function value are summarized in the 
Boilers Calculations spreadsheet as shown below:
 Figure 7.477-58
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Optimizer Operation 7-59
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Th7.9 References
 1 Box, M.J. “A New method of Constrained Optimization and a 
Comparison with other Methods,” Computer J., 8, 42-45, 1965.
 2 Press, W.H., et al, “Numerical Recipes in C,” Cambridge university 
Press, 1988.
 3 Kuester, J.L. and Mize, J.H., “Optimization Techniques with FORTRAN,” 
McGraw-Hill Book Co., 1973.
 4 Harwell Subroutine Library, Release 10, Advanced Computing Dept., 
AEA Industrial Technology, Harwell laboratory, England, 1990.
 5 Powell, M.J.D., “A Fast Algorithm for Non-Linearly Constrained 
Optimization Calculations,” Numerical Analysis, Dundee, 1977, 
Lecture Notes in Math. 630, Springer-Verlag, 1978.
 6 Chamberlain R.M. and Powell, M.J.D., “The Watchdog Technique for 
Forcing Convergence in Algorithms for Constrained Optimization,” 
Mathematical Programming Study, 16, 1-17, 1982.7-59
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Th7-60
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Th8  Reactor Operationsw.cadfamily.com    EMa
e document is for study 8.1  CSTR/General Reactors.................................................................. 3
8.1.1  Adding a CSTR/General Reactors ................................................ 4
8.2  CSTR/General Reactors Property View........................................... 5
8.2.1  Design Tab .............................................................................. 6
8.2.2  Conversion Reactor Reactions Tab............................................. 10
8.2.3  CSTR Reactions Tab ................................................................ 17
8.2.4  Equilibrium Reactor Reactions Tab ............................................ 22
8.2.5  Gibbs Reactor Reactions Tab .................................................... 28
8.2.6  Rating Tab............................................................................. 32
8.2.7  Worksheet Tab ....................................................................... 36
8.2.8  Dynamics Tab ........................................................................ 37
8.3  Yield Shift Reactor ....................................................................... 42
8.3.1  Yield Shift Reactor Property View.............................................. 45
8.3.2  Design Tab ............................................................................ 47
8.3.3  Model Config Tab.................................................................... 49
8.3.4  Composition Shift Tab ............................................................. 52
8.3.5  Property Shift Tab .................................................................. 65
8.3.6  Worksheet Tab ....................................................................... 73
8.3.7  Dynamics Tab ........................................................................ 73
8.4  Plug Flow Reactor ........................................................................ 74
8.4.1  Adding a Plug Flow Reactor (PFR) ............................................. 77
8.5  Plug Flow Reactor (PFR) Property View ....................................... 78
8.5.1  PFR Design Tab ...................................................................... 79
8.5.2  Reactions Tab ........................................................................ 87
8.5.3  Rating tab ............................................................................. 96
8.5.4  Work Sheet Tab...................................................................... 998-1
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8-2 Reactor Operations 
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The document is for study 8.5.5  Performance Tab .....................................................................99
8.5.6  Dynamics Tab.......................................................................1028-2
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Th8.1 CSTR/General 
Reactors
With the exception of the Plug Flow Reactor (PFR), all of the 
reactor operations share the same basic property view. The 
primary differences are the functions of the reaction type 
(conversion, kinetic, equilibrium, heterogeneous catalytic or 
simple rate) associated with each reactor. As opposed to a 
separator or general reactor with an attached reaction set, 
specific reactor operations can only support one particular 
reaction type. For instance, a conversion reactor only functions 
properly with conversion reactions attached. If you try to attach 
an equilibrium or a kinetic reaction to a conversion reactor, an 
error message appears. The GIBBS reactor is unique in that it 
can function with or without a reaction set.
You have a great deal of flexibility in defining and grouping 
reactions. You can:
• Define the reactions inside the Basis Manager, group 
them into a set and then attach the set to your reactor.
• Create reactions in the Reaction Package in the main 
flowsheet, group them into a set, and attach the set to 
the reactor.
• Create reactions and reaction sets in the Basis 
Environment and make changes in the Main 
Environment's Reaction Package.
Regardless of the approach, the reactions you define are visible 
to the entire flowsheet. In other words, a reaction set can be 
attached to more than one reactor.
However, there are some subtleties of which you must be aware. 
When you make a modification to a reaction via a reactor, the 
change is only seen locally, in that particular reactor. 
Modifications made to a reaction in the Basis Environment or in 
the Reaction Package are automatically reflected in every 
reactor using the reaction set, provided you have not made 
changes locally. Local changes are always retained. 
Refer to Chapter 5 - 
Reactions of the 
HYSYS Simulation 
Basis guide or Section 
5.3 - Reaction 
Package of the HYSYS 
User Guide for details 
on installing reactions 
and Reaction Sets.8-3
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8-4 CSTR/General Reactors
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ThTo override local changes and return the global parameters to a 
reaction, you must press the DELETE key when the cursor is in 
the cell which contains the local change.
To remove local changes, select the appropriate cell and press 
the DELETE key.
The four reactors which share common property views include:
• CSTR (Continuous-Stirred Tank Reactor)
• GIBBS Reactor
• Equilibrium Reactor
• Conversion Reactor
• Yield Shift Reactor
The last four reactors are referred to as General Reactors. In 
order to avoid redundancy, CSTR, Gibbs, Equilibrium, and 
Conversion reactor operations are discussed co-currently. In 
areas of the property view where there are differences, such as 
the Reactions tab, the differences are clearly noted.
The Yield Shift and PFR have a different property view from the 
other reactors. As a result it is discussed in Section 8.3 - Yield 
Shift Reactor and Section 8.4 - Plug Flow Reactor.
8.1.1 Adding a CSTR/General 
Reactors
There are two ways that you can add a reactor operation to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Reactors radio button.
3. From the list of available unit operations, select the reactor 
type you want to add: Cont. Stirred Tank Reactor, 
Conversion Reactor, Equilibrium Reactor, Gibbs Reactor, or 
Yield Shift Reactor.
4. Click the Add button. 8-4
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ThOR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Do one of the following:
• For continuous-stirred tank reactor, double-click the 
CSTR icon. The CSTR property view appears. 
• For Conversion, Equilibrium, Gibbs, and Yield Shift 
reactors, click the General Reactors icon to open the 
General Reactors object palette. 
In the General Reactors object palette, double-click on 
the appropriate reactor operation icon.
The property view for the selected Reactor operation appears.
8.2 CSTR/General 
Reactors Property View
The CSTR and General Reactors property view contains the 
following tabs:
• Design
• Reactions
• Rating
• Worksheet
• Dynamics
 Figure 8.1
CSTR icon
General 
Reactors icon
General Reactors 
object palette
Conversion 
Reactors icon
Equilibrium 
Reactors icon
Gibbs Reactor 
icon
Yield Shift 
Reactors icon8-5
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8-6 CSTR/General Reactors Property 
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Th8.2.1 Design Tab
The Design tab contains several pages, which are briefly 
described in the table below. 
Connections Page
The Connections page, is the same for both the CSTR and the 
General Reactors.
Page Description
Connections Connects the feed, product, and energy streams to the 
reactor. For more information, refer to the section below.
Parameters Sets heat transfer and pressure drop parameters for the 
reactor. 
User 
Variables
Enables you to create and implement your own user 
variables for the current operation. 
Notes Allows you to add relevant comments which are exclusively 
associated with the unit operation.
 Figure 8.2
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information on 
the Notes page, refer to 
Section 1.3.5 - Notes 
Page/Tab.8-6
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ThThe Connections page consists of the following objects described 
in the table below. 
Parameters Page
The Parameters page allows you to specify the pressure drop, 
vessel volume, duty, and solving behaviour.
Object Input Required
Name Contains the name of the reactor. You can edit the name of 
the reactor at any time by typing in a new name in the 
Name field.
Inlets / Feed 
Streams
Connects a single feed or multiple feed streams to the 
reactor. You can either type in the name of the stream or if 
you have pre-defined your stream select it from the drop-
down list.
Vapour 
Outlet
Connects the vapour product stream to the reactor. You can 
either type in the name of the stream or if you have pre-
defined your stream select it from the drop-down list.
At least one product stream is required.
Liquid Outlet 
/ Product 
Stream
Connects the liquid product stream to the reactor. You can 
either type in the name of the stream or if you have pre-
defined your stream select it from the drop-down list.
Energy 
(Optional)
Connects or creates an energy stream if one is required for 
the operation.
Fluid 
Package
Enables you to select a fluid package to be associated to 
the reactor.
 Figure 8.38-7
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ThObject Description
Delta P / 
Pressure Drop
Contains the pressure drop across the vessel. The 
pressure drop is defined as: 
(8.1)
where:
P = vessel pressure
Pv = pressure of vapour product stream
Pl = pressure of liquid product stream
Pfeed = pressure of feed stream (assumed to be 
the lowest pressure of all the feed streams)
 = pressure drop in vessel (Delta P)
The default pressure drop across the vessel is zero.
The vessel pressure is used in the reaction 
calculations.
Duty If you have attached an energy stream, you can 
specify whether it is to be used for heating or for 
cooling by selecting the appropriate radio button. You 
also have a choice of specifying the applied duty, or 
having HYSYS calculate the duty. For the latter case, 
you must specify an outlet temperature for a reactor 
product stream.
The steady state Reactor energy balance is defined 
below:
(8.2)
where:
Duty = heating (+ve) or cooling (-ve) by the 
optional energy stream
Hvapour = heat flow of the vapour product stream
Hliquid = heat flow of the liquid product stream
Hfeed = heat flow of the feed stream(s)
The enthalpy basis used by HYSYS is equal to the ideal 
gas enthalpy of formation at 25°C and 1 atm. As a 
result, the heat of reaction calculation is amalgamated 
into any product/reactant enthalpy difference.
ΔP Pfeed Pv– Pfeed Pl
P Pv Pl==
–= =
ΔP
Duty Hvapour Hliquid Hfeed–+=8-8
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ThHeating /Cooling If you change from Heating to Cooling (or vice versa), 
the magnitude of the energy stream does not change. 
However, the sign changes in the energy balance. For 
Heating, the duty is added. For Cooling, the duty is 
subtracted.
Volume The total volume of the vessel and is user specified. 
While not necessarily required for solving Conversion, 
GIBBS or Equilibrium reactors in Steady State mode, 
this value must be entered for CSTR.
The vessel volume, together with the liquid level set 
point, define the amount of holdup in the vessel. The 
amount of liquid volume or holdup in the vessel at any 
time is given by the following expression:
(8.3)
where:
PV(%Full) =   liquid level in the vessel
The vessel volume is necessary when modeling 
reactors in steady state, as it determines the residence 
time.
Liquid Level Displays the liquid level of the reactor expressed as a 
percentage of the Full Vessel Volume.
Liquid Volume Not set by the user, this value is calculated from the 
product of the volume (vessel volume) and liquid level 
fraction. It is only active when the Volume field 
contains a valid entry.
Act as a 
Separator When 
Cannot Solve
Only available for Conversion and Equilibrium reactors, 
this option allows you to operate the reactor as a 
simple 2 phase separator whenever the reactor does 
not solve.
Single Phase Allows you to specify a single phase reaction. 
Otherwise HYSYS considers it a vapour-liquid reaction.
Type Only available for the Gibbs reactor, you have two 
options for the type of reactor you want:
• Separator. A two phase Gibbs Reactor.
• Three Phase. A three phase Gibbs Reactor.
Object Description
Holdup Vessel Volume PV %Full( )
100
----------------------------×=8-9
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Th8.2.2 Conversion Reactor 
Reactions Tab
The Conversion Reactor is a vessel in which conversion reactions 
are performed. You can only attach reaction sets that contain 
conversion reactions. Each reaction in the set proceeds until the 
specified conversion is attained or until a limiting reactant is 
depleted.
The Reactions tab, consists of the following pages: 
• Details
• Results
Details Page
You can attach the reaction set to the operation and specify the 
conversion for each reaction in the set on the Details page. The 
reaction set can contain only conversion reactions.
 Figure 8.4
Conversion Reactor icon
Refer to Section 5.3.2 - 
Conversion Reaction 
in the HYSYS 
Simulation Basis guide 
for details on creating 
Conversion Reaction 
Sets and Conversion 
Reactions.8-10
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ThThe Details page consists of four objects as described in the 
table below.
Stoichiometry Radio Button
When you select the Stoichiometry radio button, the 
Stoichiometry Info group appears. The Stoichiometry Info group 
allows you to examine the components involved in the selected 
reaction, their molecular weights as well as their stoichiometric 
coefficients.  
Object Description
Reaction Set Allows you to select the appropriate conversion 
reaction set.
Reaction You must select the appropriate conversion reaction 
from the selected Reaction Set.
View Reaction 
button
Opens the Reaction property view for the reaction 
currently selected in the Reaction drop-down list. The 
Reaction property view allows you to edit the 
reaction.
[Radio buttons] The three radio buttons on the Details page are: 
• Stoichiometry
• Basis
• Conversion
The three radio buttons allow you to toggle between 
the Stoichiometry group, the Basis group or the 
Conversion group (each group is described in the 
following sections).
 Figure 8.5
The Balance Error (for the reaction stoichiometry) and the 
Reaction Heat (Heat of Reaction at 25°C) are also shown for 
the current reaction.8-11
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ThBasis Radio Button
When you select the Basis radio button, the Basis group 
appears. In the Basis group, you can view the base component, 
the conversion, and the reaction phase for each reaction in the 
reaction set.
Conversion Radio Button
When you select the Conversion radio button, the Fractional 
Conversion Equation group appears. The Fractional Conversion 
Equation group allows you to implement a conversion model 
based on the Conversion(%) equation listed.  
 Figure 8.6
 Figure 8.7
In the Fractional Conversion Equation group, parameters 
shown in red or blue colour indicate that the variable can be 
cloned.8-12
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ThThe parameters for the attached conversion reaction(s) can be 
cloned as local variables belonging to the Conversion Reactor. 
Therefore, you can either use the parameters specified in the 
reaction(s) from the attached reaction set by clicking the Use 
Default checkbox or specifying locally the values within the 
Fractional Conversion Equation group.
View Reaction Button
When you click the View Reaction button, the Conversion 
Reaction property view of the reaction currently selected in the 
Reaction drop-down list appears.
Any changes made to the Conversion Reaction property view are 
made globally to the selected Reaction and any Reaction Sets 
which contain the Reaction. For example, if any change is made 
to the reaction shown in the figure above, the change is carried 
over to every other instance in which this Reaction is used. It is 
therefore recommended that changes which are Reactor specific 
(in other words, changes which are only meant to affect one 
Reactor) are made within the Reactions tab. 
 Figure 8.88-13
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ThResults Page
The Results page displays the results of a converged reactor. 
The page consists of the Reactor Results Summary group which 
contains two radio buttons: 
• Reaction Extents
• Reaction Balance
The type of results displayed on the Results page depend on the 
radio button selected.
Reaction Extents Radio Button
When the Reaction Extents radio button is selected, the Results 
page appears as shown in the figure below.
You can change the specified conversion for a reaction 
directly on this page.
 Figure 8.98-14
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ThThe Reactor Results Summary group displays the following 
results for a converged reactor:
Notice that the actual conversion values do not match the 
specified conversion values. Rxn-3 proceeds first and is halted 
when a limiting reactant is exhausted. The sum of the specified 
conversions for Rxn-1 and Rxn-2 is 100%, so all of the 
remaining base component can be consumed, provided a 
limiting reactant is not fully consumed beforehand. All of the 
base component is consumed, and this is reflected in the actual 
conversion totalling 100%.
Result Field Description
Rank Displays the current rank of the reaction. For multiple 
reactions, lower ranked reactions occur first.
When there are multiple reactions in a Reaction Set, HYSYS 
automatically ranks the reactions. A reaction with a lower 
ranking value occurs first. Each group of reactions of equal 
rank can have an overall specified conversion between 0% 
and 100%.
Actual % 
Conversion 
Displays the percentage of the base component in the feed 
stream(s) which has been consumed in the reaction.
Base 
Component
The reactant to which the calculation conversion is based 
on.
Rxn Extent Lists the molar rate consumption of the base component in 
the reaction divided by its stoichiometric coefficient 
appeared in the reaction.
Any changes made to the global reaction affect all Reaction 
Sets to which the reaction is attached, provided local 
changes have not been made.8-15
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ThReaction Balance Radio Button
When the Reaction Balance radio button is selected, the 
Reaction Balance option provides an overall component 
summary for the Conversion Reactor. All components which 
appear in the fluid package are shown here.
Values appear after the solution of the reactor has converged. 
The Total Inflow rate, the Total Reacted rate and the Total 
Outflow rate for each component are provided on a molar basis. 
Negative values indicate the consumption of a reactant, while 
positive values indicate the appearance of a product.
 Figure 8.108-16
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Th8.2.3 CSTR Reactions Tab
The CSTR is a vessel in which Kinetic, Heterogeneous Catalytic, 
and Simple Rate reactions can be performed. The conversion in 
the reactor depends on the rate expression of the reactions 
associated with the reaction type. The inlet stream is assumed 
to be perfectly (and instantaneously) mixed with the material 
already in the reactor, so that the outlet stream composition is 
identical to that of the reactor contents. Given the reactor 
volume, a consistent rate expression for each reaction and 
the reaction stoichiometry, the CSTR computes the 
conversion of each component entering the reactor.
On the Reactions tab, you can select a reaction set for the 
operation. You can also view the results of the solved reactor 
including the actual conversion of the base component. The 
actual conversion is calculated as the percentage of the base 
component that was consumed in the reaction.
where:  
X = actual % conversion 
NAin = base component flowrate into the reactor
NAout = base component flowrate (same basis as the inlet 
rate) out of the reactor
The Reactions tab contains the following pages:
• Details
• Results
(8.4)
For more information on 
Kinetic, Heterogeneous 
Catalytic and Simple 
Rate reactions, refer to 
Chapter 5 - Reactions 
in the HYSYS 
Simulation Basis 
guide.
CSTR icon
X
NAin
NAout
–
NAin
--------------------------- 100%×=8-17
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ThDetails Page
The Details page allows you to attach the appropriate reaction 
set to the operation. 
As mentioned earlier in this section, the selected reaction set 
can contain only Kinetic, Heterogeneous Catalytic, and Simple 
Rate reactions. 
The page consists of four objects, which are described in the 
table below.
 Figure 8.11
Object Description
Reaction Set Allows you to select the reaction set you want to use in the 
reactor.
Reaction Allows you to select the reaction you want to use in the 
reactor.
View 
Reaction
Opens the Reaction property view for the selected Reaction. 
This allows you to edit the reaction globally.
Specifics Toggles between the Stoichiometry group or the Basis 
group (the groups are described in the following sections).8-18
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ThStoichiometry Radio Button
When you select the Stoichiometry radio button, the 
Stoichiometry group appears. The Stoichiometry group allows 
you to examine the components involved in the currently 
selected reaction, their molecular weights as well as their 
stoichiometric coefficients. 
Basis Radio Button
When you select the Basis radio button, the Basis group 
appears. In the Basis group, you can view the base component, 
the reaction rate parameters (for example A, E, ß, A’, E’, and ß’) 
and the reaction phase for each reaction in the attached set. 
 Figure 8.12
The Balance Error (for the reaction stoichiometry) and the 
Reaction Heat (Heat of Reaction at 25°C) are also shown for 
the current reaction.
 Figure 8.138-19
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8-20 CSTR/General Reactors Property 
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ThYou can view the properties for a specific reaction by selecting 
the reaction from the Reaction drop-down list, and its data 
appears in the Basis group.
Changes can be made to the reaction rate parameters 
(frequency factor, A, activation energy, E, and ß), but these 
changes are reflected only in the active reactor. The changes do 
not affect the global reaction.
To return the global reaction values, select the appropriate Use 
Default checkbox. For instance, if you have made a change to 
the forward reaction activation energy (E), the Use Default E 
checkbox is inactive. Select this checkbox to return to the global 
E value.
Results Page
The Results page displays the results of a converged reactor. 
The page is made up of the Reaction Results Summary group 
which contains two radio buttons: 
• Reaction Extents
• Reaction Balance
Reaction Extents Radio Button
When you select the Reaction Extents radio button, the Reaction 
Extents option displays the following results for a converged 
reactor: 
Result Field Description
Actual % 
Conversion 
Displays the percentage of the base component in the 
feed stream(s) which has been consumed in the 
reaction.
Base Component The reactant to which the conversion is applied.
Rxn Extent Lists the molar rate consumption of the base 
component in the reaction divided by its stoichiometirc 
coefficient appeared in the reaction.8-20
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ThReaction Balance Radio Button
When you select the Reaction Balance radio button, the Reaction 
Balance option provides an overall component summary for the 
CSTR. All components which appear in the fluid package are 
shown here.
Values appear after the solution of the reactor has converged. 
The Total Inflow rate, the Total Reacted rate and the Total 
Outflow rate for each component are provided on a molar basis. 
Negative values indicate the consumption of a reactant, while 
positive values indicate the appearance of a product.
 Figure 8.14
 Figure 8.158-21
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8-22 CSTR/General Reactors Property 
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Th8.2.4 Equilibrium Reactor 
Reactions Tab
The Equilibrium reactor is a vessel which models equilibrium 
reactions. The outlet streams of the reactor are in a state of 
chemical and physical equilibrium. The reaction set which you 
attach to the Equilibrium Reactor can contain an unlimited 
number of equilibrium reactions, which are simultaneously or 
sequentially solved. Neither the components nor the mixing 
process need be ideal, since HYSYS can compute the chemical 
activity of each component in the mixture based on mixture and 
pure component fugacities.
You can also examine the actual conversion, the base 
component, the equilibrium constant, and the reaction extent 
for each reaction in the selected reaction set. The conversion, 
the equilibrium constant and the extent are all calculated based 
on the equilibrium reaction information which you provided 
when the reaction set was created.
The Reactions tab contains the following pages:
• Details
• Results
Details Page
The Details page consists primarily of four radio buttons:
• Stoichiometry
• Basis
• Ln[K]
• Table
Any changes made to the global reaction affect all reaction 
sets to which the reaction is attached, provided local 
changes have not been made.
Refer to Section 5.3.3 - 
Equilibrium Reaction 
in the HYSYS 
Simulation Basis guide 
for details on creating 
and installing 
Equilibrium Reactions.
Equilibrium Reactor icon8-22
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ThStoichiometry Radio Button
When you select the Stoichiometry radio button, the 
Stoichiometry Info group appears. The Stoichiometry group 
allows you to view the stoichiometric formula of the reaction 
currently selected in the Reaction drop-down list. 
The Balance Error (for the reaction stoichiometry) and the 
Reaction Heat (Heat of Reaction at 25°C) are also shown for the 
current reaction.
Basis Radio Button
When you select the Basis radio button, Basis group appears.
 Figure 8.16
Changes made to the global reaction affect all reaction sets 
which contain the reaction, and thus all operations to which 
the reaction set is attached.
 Figure 8.17
Refer to Section 5.3.3 
- Equilibrium 
Reaction of the HYSYS 
Simulation Basis 
guide for details on 
Equilibrium Constant 
source.8-23
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8-24 CSTR/General Reactors Property 
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ThThe Basis group allows you to view or edit (locally) various 
information for each reaction in the reaction set including the: 
• Basis for the equilibrium calculations.
• Phase in which the reaction occurs.
• Temperature Approach of the equilibrium composition.
The temperature range for the equilibrium constant, and the 
source for the calculation of the equilibrium constant is also 
shown.
Keq Radio Button
When you select the Keq radio button, the Ln(keq) group and K 
Table appears. 
The Ln(keq) group displays the Ln(Keq) relationship which may 
vary depending upon the Ln(K) Source value selected for the 
reaction.
When you select the Ln(Keq) Equation radio button in the Ln(K) 
Source group, the parameters of the equilibrium constant 
equation appear. These values are either specified when the 
reaction was created or are calculated by HYSYS. If a fixed 
equilibrium constant was provided, it is shown here.
Any of the parameters in the Ln(K) Equation group can be 
modified on this page. Changes made to the parameters only 
affect the selected reaction in the current reactor. After a change 
has been made, you can have HYSYS return the original 
calculated value by selecting the appropriate Use Default 
checkbox.
 Figure 8.18
Refer to Section 5.3.3 
- Equilibrium 
Reaction of the HYSYS 
Simulation Basis 
guide for details on the 
Equilibrium Constant 
source.
Refer to the section on 
the Basis Radio 
Button for more 
information.8-24
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ThApproach Radio Button
When you select the Approach radio button, the Fractional 
Approach group and the Temperature Approach group appear.
For each reaction in the reaction set, a fractional approach 
equation as a function of temperature is provided. Any of the 
parameters in the Approach % equation can be modified on this 
page. Changes made to the parameters only affect the selected 
reaction in the current reactor. After a change has been made, 
you can have HYSYS return the original calculated value by 
selecting the appropriate Use Default checkbox.
You can edit a reaction by clicking the View Reaction button. 
The property view for the highlighted reaction appears.
Results Page
The Results page displays the results of a converged reactor. 
The page is made up of the Results Summary group which 
contains two radio buttons: 
• Reaction Extents
• Reaction Balance
 Figure 8.19
You can change the specified conversion for a reaction 
directly on this page.
For more detailed 
information on 
equilibrium reactions, 
refer to Chapter 5 - 
Reactions in the HYSYS 
Simulation Basis guide.8-25
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ThReaction Extents
When you select the Reaction Extents radio button, the option 
displays the following results for a converged reactor:   
 Figure 8.20
Result Field Description
Actual % 
Conversion 
Displays the percentage of base component in the feed 
stream(s) which has been consumed in the reaction.
The actual conversion is calculated as the percentage of the 
base component that was consumed in the reaction.
(8.5)
where: 
X = actual % conversion
NAin = base component flowrate into the reactor
NAout = base component flowrate (same basis as the 
inlet rate) out of the reactor
Base 
Component 
The reactant to which the conversion is applied.
X
NAin
NAout
–
NAin
--------------------------- 100%×=8-26
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ThReaction Balance
When you select the Reaction Balance radio button, the Reaction 
Balance option provides an overall component summary for the 
Equilibrium Reactor. All components which appear in the 
component list related to the fluid package are shown here.
Eqm Const. The equilibrium constant is calculated at the reactor 
temperature by the following:
(8.6)
where: 
T = reactor temperature, K
A, B, C, D = equation parameters
The four parameters in Equation (8.6) are calculated by 
HYSYS if they are not specified during the installation of the 
equilibrium reaction.
The four parameters for each equilibrium equation are 
listed on the Rxn Ln(K) page.
Rxn Extent Lists the molar rate consumption of the base component in 
the reaction divided by its stoichiometirc coefficient 
appeared in the reaction.
 Figure 8.21
Result Field Description
Kln A B
T
-- C T DT+ln+ +=8-27
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ThValues appear after the solution of reactor has converged. The 
Total Inflow rate, the Total Reacted rate, and the Total Outflow 
rate for each component are provided on a molar basis. 
Negative values indicate the consumption of a reactant, while 
positive values indicate the appearance of a product.
8.2.5 Gibbs Reactor Reactions 
Tab
The Gibbs Reactor calculates the exiting compositions such that 
the phase and chemical equilibria of the outlet streams are 
attained. However, the Gibbs Reactor does not need to make 
use of a specified reaction stoichiometry to compute the outlet 
stream composition. The condition that the Gibbs free energy of 
the reacting system is at a minimum at equilibrium is used to 
calculate the product mixture composition. As with the 
Equilibrium Reactor, neither pure components nor the reaction 
mixture are assumed to behave ideally.
The versatility of the Gibbs Reactor allows it to function solely as 
a separator, as a reactor which minimizes the Gibbs free energy 
without an attached reaction set or as a reactor which accepts 
equilibrium reactions. When a reaction set is attached, the 
 Figure 8.22
Gibbs Reactor icon8-28
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Thstoichiometry involved in the reactions is used in the Gibbs 
Reactor calculations.
The Reactions tab contains the following pages:
• Overall
• Details
Overall Page
You must first select the reactor type on the Overall page. The 
objects that appear depend on the radio button you selected in 
the Reactor Type group. You can then attach a reaction set if 
necessary, and you can specify the vessel parameters on the 
Rating tab.
Reactor Type Group
In the Reactor Type group, select the radio button to define the 
method which HYSYS uses to solve the Gibbs Reactor. The table 
below describes the radio buttons.
Radio Button Description
Gibbs Reactions 
Only 
No reaction set is required as HYSYS solves the system 
by minimizing the Gibbs free energy while attaining 
phase and chemical equilibrium. You can also customize 
the maximum iteration number and equilibrium error 
tolerance in the Solving Option group.
Specify 
Equilibrium 
Reactions 
Displays the Equilibrium Reaction Sets group. When a 
reaction set is attached, the Gibbs Reactor is solved 
using the stoichiometry of the reactions involved. The 
Gibbs minimization function uses the extents of the 
attached reactions while setting any unknowns to zero. 
NO Reactions 
(=Separator) 
The Gibbs Reactor is solved as a separator operation, 
concerned only with phase equilibrium in the outlet 
streams.8-29
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ThDetails Page
The Details page consists of one group, the Gibbs Reaction 
Details group. The group consists of two radio buttons: 
• Flow Specs
• Atom Matrix 
The information that is viewable on the page depends on which 
of the two radio buttons is selected.
Flow Specs Option
When you select the Flow Specs radio button, a property view 
similar to the one in the figure below appears.
You can view the component feed and product flowrates on a 
molar basis. You can also designate any of the components as 
inert or specify a rate of production for a component.
Inert species are excluded from the Gibbs free energy 
minimization calculations. When the Inerts checkbox is selected 
for a component, values of 1 and 0 appear respectively in the 
associated Frac Spec and Fixed Spec cells, which indicates that 
the component feed flowrate equals the product flowrate.
You may want to specify the rate of production of any 
component in your reactor as a constraint on the equilibrium 
composition. The component product flowrate is calculated as 
 Figure 8.238-30
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Thfollows, based on your input of a Frac Spec value and a Fixed 
Spec value:
The Gibbs Reactor attempts to meet that flowrate in calculating 
the composition of the outlet stream. If the constraint cannot be 
met, a message appears alerting you to that effect.
Atom Matrix Option
When you select the Atom Matrix radio button, you can specify 
the atomic composition of any species for which the formula is 
unknown or unrecognized.
The atomic matrix input form displays all components in the 
case with their atomic composition as understood by HYSYS. 
You have the option to enter the composition of an unrecognized 
compound or to correct the atomic composition of any 
compound.
Total Prod = FracSpec x Total Feed + FixedSpec (8.7)
 Figure 8.248-31
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Th8.2.6 Rating Tab
The Rating tab includes the Sizing, Nozzles, and Heat Loss 
pages. Although most of the information on the three pages is 
not relevant when working in the Steady State mode, sizing a 
reactor plays an important role in calculating the holdup time. 
Sizing Page
You can define the geometry of the unit operation on the Sizing 
page. Also, you can indicate whether or not the unit operation 
has a boot associated with it. If it does, then you can specify the 
boot dimensions.
You are required to specify the rating information only when 
working with a dynamics simulation. 
 Figure 8.25
For information on 
specifying information on 
the Sizing Page, refer to 
the HYSYS Dynamic 
Modeling guide.8-32
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ThThe page consists of three main objects, which are described in 
the table below.
Geometry Group
The Geometry group contains five objects which are described in 
the table below.
Object Description
Geometry Allows you to specify the vessel geometry.
This Reactor has a 
Boot
When activated, the Boot Dimensions group 
appears.
Boot Dimensions Allows you to specify the boot dimensions of the 
vessel.
Object Description
Cylinder / 
Sphere
Toggles the shape of the vessel between Sphere and 
Cylinder. This affects the number of specifications required 
as well as the method of volume calculation. 
If you select the Cylinder, and you have specified the 
diameter and height; the vessel volume is calculated as: 
(8.8)
If you select Sphere, and you have specified either the 
height or diameter; the vessel volume is calculated as:
(8.9)
where: 
Vreactor = volume of the reactor
 Vboot = volume of the boot
 Height, Diameter = values taken from the respective 
fields
Orientation Allows you to select the orientation of the vessel. There are 
two options:
• Horizontal. The ends of the vessels are horizontally 
orientated.
• Vertical. The ends of the vessel are vertically 
orientated.
Vreactor
Diameter2
4
---------------------------π Height×⎝ ⎠
⎛ ⎞ Vboot+=
Vreactor
Height or Diameter( )3π
6
--------------------------------------------------------- Vboot+=8-33
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ThThe Geometry group contains three fields:
• Volume
• Diameter
• Height (or Length depending on orientation)
Boot Dimensions
If the reactor you are rating has a boot, you can include its 
volume in the total vessel volume by selecting the This Reactor 
has a Boot checkbox. The Boot Dimensions group appears. 
Volume Contains the total volume of the vessel.
There are three possibilities for values in this field:
• If the height and/or diameter have been entered, this 
field displays the value calculated using either 
Equation (8.8) or Equation (8.9). 
• If you enter a value into this field and either the height 
(length) or diameter is specified, HYSYS back 
calculates the other parameter using either Equation 
(8.8) or Equation (8.9). This is only possible with 
cylindrical vessels as spherical vessels have the height 
equal to the diameter.
• If you enter a value into this field (and only this field) 
both the height (length) and diameter are calculated 
assuming a ratio of 3/2 (in other words, 
Height:Diameter ratio).
Diameter Holds the diameter of the vessel. If the vessel is a Sphere, 
then it is the same value as the Height (Length).
Height / 
Length
Holds the height or length of the vessel depending on the 
vessels orientation (vertical or horizontal). If the vessel is a 
Sphere, then it is the same value as the diameter.
If you specify the Volume then you are not required to 
specify the other two parameters as HYSYS calculates a 
Height (or Length) and Diameter assuming a ratio of Height 
to Diameter of 3/2. 
You can change the default ratio, by specifying one of the 
two dimensions (either Height or Diameter) and the third is 
automatically calculated using either Equation (8.8) or 
Equation (8.9).
Object Description8-34
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ThThe Boot Dimensions group consists of two fields, which are 
described in the table below.
The volume of the boot is calculated using a simple cylindrical 
volume calculation:
and the default boot volume is:
The total Reactor volume can estimated using the boot 
diameter, boot height or the default boot volume.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
Unlike steady state vessel operations, the placement of feed and 
product nozzles on a dynamic reactor operation has physical 
meaning. The composition of the exit stream depends on the 
exit stream nozzle’s location and diameter in relation to the 
physical holdup level in the vessel. 
• If the product nozzle is located below the liquid level in 
the vessel, the exit stream draws material from the liquid 
holdup. 
Field Description
Boot 
Diameter
The diameter of the boot. The default value is usually 1/3 
the reactor diameter.
Boot Height The height of the boot which is defaulted at 1/3 the reactor 
diameter (sphere) or 1/3 the reactor height or length 
(cylinder).
(8.10)
(8.11)
VBoot π Boot Diameter
2
----------------------------------⎝ ⎠
⎛ ⎞ 2
Boot Height(× or Boot Length )=
VBoot π Diameter
6
------------------------⎝ ⎠
⎛ ⎞ 2 Diameter
3
------------------------×=
π Diameter( )3
72
-----------------------------------=
Refer to Section 1.3.6 
- Nozzles Page for 
more information.8-35
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8-36 CSTR/General Reactors Property 
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Th• If the product nozzle is located above the liquid level, the 
exit stream draws material from the vapour holdup. 
• If the liquid level lies across a nozzle, the phase fraction 
of liquid in the product stream varies linearly with how 
far up the liquid is in the nozzle. 
Essentially, all vessel operations in HYSYS are treated similarly. 
The composition and phase fractions (in other words, fraction of 
each phase) of every product stream depends solely on the 
relative levels of each phase in the holdup and the location the 
product nozzles. 
Heat Loss Page
The Heat Loss page allows you to specify which Heat Loss Model 
you want to implement, and to define the parameters associated 
with each model. 
8.2.7 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
A vapour product nozzle does not necessarily produce pure 
vapour and a 3-phase separator may not produce two 
distinct liquid phase products from its product nozzles.
The PF Specs page is relevant to dynamics cases only.
For information refer to 
Heat Loss Page section 
in Chapter 10 - 
Separation 
Operations.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.8-36
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Th8.2.8 Dynamics Tab
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages accessible 
through this tab. 
Specs Page
The Specs page contains information regarding initialization 
modes, vessel geometry, and vessel dynamic specifications. 
Model Details
You can determine the composition and amount of each phase in 
the vessel holdup by specifying different initialization modes. 
HYSYS forces the simulation case to re-initialize whenever the 
initialization mode is changed. 
 Figure 8.268-37
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ThThe radio buttons in the Model Details group are described in 
the table below. 
The Enable Explicit Reaction Calculations is defaulted to be used 
for dynamic run reaction solver.
The Lag Rxn Temperature is designed to speed up the dynamic 
run for the reaction solver when the run has to invoke the 
steady state reaction solver. Mathematically, when you select 
the Lag Rxn Temperature checkbox, the reaction solver 
flashes with the explicit Euler method. Otherwise, for a dynamic 
run, the steady state reaction solver always flashes with the 
implicit Euler methods which could be slow with many iterations.
The Lag Rxn Temperature may cause some instability due to the 
nature of the explicit Euler method. But it must compromise 
with the dynamic step size.
In the Model Details group, you can specify the vessel geometry 
parameters. 
• Vessel Volume
• Vessel Diameter
• Vessel Height (Length)
• Vessel Geometry (Level Calculator)
Initialization Mode Description
Initialize from 
Products
The composition of the holdup is calculated from a 
weighted average of all products exiting the 
holdup. A PT flash is performed to determine other 
holdup conditions. The liquid level is set to the 
value indicated in the Liq Volume Percent field.
Dry Startup The composition of the holdup is calculated from a 
weighted average of all feeds entering the holdup. 
A PT flash is performed to determine other holdup 
conditions. The liquid level in the Liq Volume 
Percent field is set to zero.
Initialize from User The composition of the liquid holdup in the vessel 
is user specified. The molar composition of the 
liquid holdup can be specified by clicking the Init 
Holdup button. The liquid level is set to the value 
indicated in the Liq Volume Percent field.
The vessel geometry parameters can be specified in the 
same manner as those specified in the Geometry group for 
the Sizing page of the Rating tab.8-38
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ThLiquid Volume Percent
You can modify the level in the vessel at any time. HYSYS then 
uses that level as an initial value when the Integrator has 
started, depending on the initialization mode you selected.
Fraction Calculator
The Fraction Calculator determines how the level in the tank, 
and the elevation and diameter of the nozzle affects the product 
composition. 
The following is a description of the Fraction Calculator option: 
Use Levels and Nozzles.The nozzle location and vessel 
liquid level affect the product composition as detailed in the 
Nozzles Page of Section 8.2.6 - Rating Tab.   
Dynamic Specifications
The frictional pressure loss at the feed nozzle is a dynamic 
specification in HYSYS. It can be specified in the Feed Delta P 
field. The frictional pressure losses at each product nozzle are 
automatically set to zero by HYSYS.
If you want to model friction loss at the inlet and exit stream, it 
is suggested you add valve operations. In this case, flow into 
and out of the vessel is realistically modeled.
The vessel pressure can also be specified. This specification can 
be made active by selecting the checkbox beside the Vessel 
Pressure field. This specification is typically not set since the 
The Fraction Calculator defaults to the correct mode for all 
unit operations and does not typically require any changing.
It is recommended that you enter a value of zero in the Feed 
Delta P field because a fixed pressure drop in the vessel is 
not realistic for all flows.8-39
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8-40 CSTR/General Reactors Property 
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Thpressure of the vessel is usually a variable and determined from 
the surrounding pieces of equipment.
Holdup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
The Vessel Levels group displays the following variables for each 
of the phases available in the vessel:
• Level. Height location of the phase in the vessel.
• Percent Level. Percentage value location of the phase in 
the vessel.
• Volume. Amount of space occupied by the phase in the 
vessel.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
 Figure 8.27
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.8-40
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ThHeat Exchanger Page
The Heat Exchanger page allows you to select whether the 
reactor is heated, cooled, or left alone. You can also select the 
method used to heat or cool the reactor.
The options available in the Heat Exchanger page depends on 
which radio button you select:
• If you select the None radio button, this page is blank 
and you do not have to specify an energy stream in the 
Connections page (from the Design tab) for the reactor 
operation to solve.
• If you select the Duty radio button, this page contains 
the standard heater or cooler parameters and you have 
to specify an energy stream in the Connections page 
(from the Design tab) for the reactor operation to solve.
• The Tube Bundle radio button option is not available for 
the reactor operations.
 Figure 8.28
If you switch from Duty option to None option, HYSYS 
automatically disconnects the energy stream associated to 
the Duty options.
Refer to Duty Radio 
Button for more 
information.8-41
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8-42 Yield Shift Reactor
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Th8.3 Yield Shift Reactor
The Yield Shift reactor unit operation supports efficient modeling 
of reactors by using data tables to perform shift calculations. 
The operation can be used for complex reactors where no model 
is available, or where models that are too computationally 
expensive.
Theory
There are two methods to configure the reaction in the Yield 
Shift reactor: Yield Only or Percent Conversion. Depending on 
what information you supply the reactor automatically use the 
appropriate equation to solve the reaction.
Product Stream Mass Fractions
The following equations are used to calculate the product stream 
mass fractions:
• For Component Percent Conversion method:
where:
yk = mass fraction of component k in product stream
xk = mass fraction of component k in feed stream
convk = component type (reacting or non-reacting) for 
component k
(8.12)
The sum of the component mass fraction must equal one.
yk xk 1 convk–( )× cur_yieldk convtotal×+=8-42
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ThNC = number of components
base_yieldk = base yield of component k
NV = number of input variables
NRi = number of ranges for each input variable i
 = base shift value for component k
effi = efficiency for design variable i, the values are user-
specified in the Efficiencies Page
 = minimum range value of dataset j of design variable i
 = maximum range value of dataset j of design variable 
i
(8.13)
(8.14)
(8.15)
(8.16)
(8.17)
The sum of the base shift values for all the components 
should equal zero.
convtotal xk convk×
k 0=
NC
∑=
cur_yieldk base_yieldk total_shiftk+=
There are two methods to 
obtain the base yield 
value:
• Calculate the value 
from raw data, see 
Design Data:Base 
Page.
• Specify the value, 
see Base Yields 
Page.
total_shiftk cur_adji
j base_adji
j–( ) base_shifti
j( )k effi××[ ]
j 0=
NRi
∑
i 0=
NV
∑=
cur_adji
j Max pi
j min, Min pi
j max, cur_valuei,( ),[ ]=
base_adji
j Max pi
j min, Min pi
j max, base_valuei,( ),[ ]=
base_shifti
j( )k
pi
j min,
pi
j max,8-43
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8-44 Yield Shift Reactor
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Thcur_valuei = current value for design variable i
base_valuei = base value for design variable i
• For Yield Only Conversion method:
where:
yk = mass fraction of component k in product stream
xk = mass fraction of component k in feed stream
 = total conversion value for the reaction
base_yieldk = base yield of component k
 = total shift value, see Equation (8.15)
If the range values are not specified, HYSYS assumes 
negative and positive infinity values for minimum and 
maximum range respectively.
(8.18)
The sum of the component mass fraction must equal one.
(8.19)
There are two methods to obtain the base yield value:
• Calculate the value from raw data, see Design 
Data:Base Page.
• Specify the value, see Base Yields Page.
yk xk cur_yieldk conversiontotal×+=
conversiontotal
cur_yieldk base_yieldk total_shiftk+=
total_shiftk8-44
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Th8.3.1 Yield Shift Reactor 
Property View
The Yield Shift Reactor property view contains the following 
tabs:
• Design
• Model Config 
• Composition Shift
• Property Shift
• Worksheet8-45
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8-46 Yield Shift Reactor
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Th• Dynamics
 Figure 8.298-46
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Th8.3.2 Design Tab
The Design tab contains the options that enables you to 
configure the Yield Shift reactor. The options are grouped in the 
following pages:
• Connections
• Parameters
• User Variables
The User Variables page enables you to create and 
implement your own user variables for the current 
operation. 
• Notes
The Notes page enables you to add relevant comments 
which are exclusively associated with the unit operation.
Connections Page
The Connections page enables you to configure the material and 
energy streams flowing in and out of the reactor. 
 Figure 8.30
Object Description
Name field Enables you to modify the name of the reactor.
Fluid Pkg field Enables you to select the fluid package associated 
to the reactor.
Feed Streams table Enables you to specify or select inlet streams 
flowing into the reactor.
Product Stream field Enables you to specify or select an outlet stream 
flowing out of the reactor.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information on 
the Notes page, refer to 
Section 1.3.5 - Notes 
Page/Tab.8-47
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8-48 Yield Shift Reactor
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ThParameters Page
The Parameters page allows you to specify the pressure drop of 
the reactor.
The Pressure Drop field enables you to specify the pressure 
drop in the vessel of the reactor. The pressure drop is defined 
as:
where:
 = pressure drop in vessel (Delta P)
Pproduct = pressure of the product stream
Pfeed = pressure of the feed stream, assumed to be the lowest 
pressure of all the feed streams
The default pressure drop across the vessel is zero. 
Make-up Energy 
Stream (Optional)
Enables you to connect or create a make-up 
energy stream if one is required for the operation.
If you specify any heat adjustment for the 
reaction, HYSYS automatically creates a make-up 
energy stream to represent the heat transfer.
Energy (Optional) Enables you to connect or create an energy 
stream if one is required for the operation.
 Figure 8.31
(8.20)
Object Description
ΔP Pfeed Pproduct–=
ΔP8-48
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Th8.3.3 Model Config Tab
The Model Config tab contains the options for configuring the 
reactor. These options are split into the following pages:
• Design Parameters
• Design Variables
• Heat of Reaction
Design Parameters Page
The Design Parameters page enables you to specify other design 
parameters that affect the reaction in the reactor.  
 Figure 8.32
These parameters are optional and you do not have to supply 
any parameter information to get the reactor to solve.
Object Description
Name column Enables you to change the name of the selected 
design parameter.
Value column Enables you to specify the design parameter 
value.
Unit Type column Enables you to select the unit type for the design 
parameter.
When a new 
parameter... 
checkbox
Enables you to toggle between adding or not 
adding a new design variable every time a new 
design parameter is added.8-49
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ThDesign Variables Page
The Design Variable page enables you to insert, edit, and 
remove variables used in the reaction calculations for the 
reactor. 
Insert New 
Parameter button
Enables you to add a new design parameter.
Remove Selected 
Parameter button
Enables you to remove the selected operation 
parameter in the Operating Parameters table.
You can select multiple parameters by pressing 
and holding the CTRL or SHIFT key while 
selecting the parameters.
 Figure 8.33
Object Description
Name column Enables you to modify the name of the design variable.
Assoc Object 
column
Displays the name of the object associated to the 
design variable.
Variable column Displays the design variable type.
Dataset No 
column
Enables you to specify the number of data set/value is 
available for the design variable.
On/Off checkbox Enables you to toggle between acknowledging or 
ignoring the design variable during calculation. A clear 
checkbox indicates you are ignoring the design 
variable.
Insert Design 
Var button
Enables you to add a design variable using the 
property view similar to the Variable Navigator 
property view.
Object Description
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for more 
information.8-50
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ThHeat of Reaction Page
The Heat of Reaction page enables you to specify heat transfer 
that occurs during reaction. 
Edit Design Var 
button
Enables you to change the selected design variable to a 
different variable.
Remove Design 
Var button
Enables you to remove the selected design variable 
from the reactor.
Set Password 
button
Enables you to set the password for the reactor.
This button is only available if you have not set a 
password for the reactor.
The password feature is available for users to protect 
the configuration data of the Yield Shift reactor.
The password feature protects the proprietary property 
of the Yield Shift reactor configuration, while enables 
the reactor to be shared among other HYSYS users.
Change 
Password button
Enables you to change the password for the reactor.
This button is only available if the reactor already 
contains a password.
 Figure 8.34
Object Description
Adjusting Factor 
column
Enables you to specify the heat transfer that occur for 
the associate component in the reactor.
If you specify a value (other than zero) for the 
adjusting factor, HYSYS automatically creates a make-
up energy stream to balance the heat transfer.
Object Description8-51
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8-52 Yield Shift Reactor
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Th8.3.4 Composition Shift Tab
The Composition Shift tab contains options to specify the 
composition shift affected by the design variables. These options 
are split into the following pages:
• Design Data: Base and Data
• Base Yields
• Base Shifts
• Efficiencies
• Results: Yields, Shift Extents, and Total Extents
Design Data Page
The Design Data page enables you to configure the yield of the 
reactor. The options are split into the following branches/pages:
• Base 
• Data 
Amount of 
Reaction column
Displays the rate of component that was consumed or 
generated during the reaction.
Adjusted Duty Displays the amount of duty for the associate 
component.
 Figure 8.35
Object Description8-52
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ThDesign Data:Base Page
The Base page enables you to specify the design base values for 
the design variables, feed stream, and product stream. These 
values are use to calculate the base yield values of the 
components.  
 Figure 8.36
You can calculate base yield values using the options in the 
Base page or specify the base yield values in the Base Yield 
page.
Object Description
Design Base Value 
column
Enables you to specify the design base values for 
the associate design variables.
Use percent 
conversion radio 
button
Enables you to model the reactor based on percent 
conversion specifications.
Use yield only radio 
button
Enables you to model the reactor based on yield 
specifications.
Feed column Displays the composition of the feed stream. You 
can edit the composition of the stream by entering 
an new value in any of the cells.
Product column Displays the composition of the product stream. 
You can edit the composition of the stream by 
entering an new value in any of the cells.
Base Conversion 
column
Enables you to specify the base conversion value 
for each component in percent value.8-53
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8-54 Yield Shift Reactor
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ThTo change the composition of a stream:
1. In the Component Base Compositions of Feed and Product 
group, select the stream you want to edit by clicking on a 
cell associated to the stream.
2. Click the Edit Compositions button. 
The component composition property view appears.
3. In the appropriate cell, enter the composition value for each 
component.
• You can modify the composition basis of the stream by 
selecting the appropriate radio button in the Composition 
Basis group.
• You can click the Erase button to remove all the 
composition values.
• You can click the Normalize button to shift all the 
composition values so that the total value equals 1.
• You can click the Cancel button to exit the component 
composition property view without accepting any of the 
changes made.
4. Click the OK button to accept the modified composition 
values.
Edit Composition 
button
Enables you to edit the composition of the selected 
stream.
Change Comp Basis 
button
Enables you to change the composition basis of 
the selected stream.
 Figure 8.37
Object Description8-54
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ThTo change the composition basis of a stream:
1. In the Component Base Compositions of Feed and Product 
group, select the stream you want to edit by clicking on a 
cell associated to the stream.
2. Click the Change Comp Basis button. 
The composition basis property view appears.
3. Select the composition basis you want by clicking the 
appropriate radio button.
You can click the Cancel button to exit the composition basis 
property view without accepting any of the changes made.
4. Click the Accept button to accept the new selection.
Calculating Base Yield Values
• Calculating the base yield values using percent 
conversion:
where:
 = base yield value for component k of dataset j
 = product stream mass fraction for component k of 
dataset j
 Figure 8.38
(8.21)
base_yieldk
j yk
j xk
j 1 convk
base–( )×–
xk
j convk
base×
k 0=
NC
∑
--------------------------------------------------------=
base_yieldk
j
yk
j
8-55
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8-56 Yield Shift Reactor
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Th = feed stream mass fraction for component k of dataset j
 = base conversion percentage value for component k
NC = number of components
• Calculating the base yield values using yield only:
where:
 = base yield value for component k of dataset j
 = product stream mass fraction for component k of 
dataset j
 = feed stream mass fraction for component k of dataset j
Design Data:Datasets Page
The Datasets page enables you to specify the data set values for 
the design variables, feed stream, and product stream. These 
values are used to calculate the component shift for each data 
set of each design variable.  
(8.22)
 Figure 8.39
xk
j
convk
base
base_yieldk
j yk
j xk
j–=
base_yieldk
j
yk
j
xk
j
8-56
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ThTo change the stream composition of a data set:
1. In the Data Sets of Design Variables group, select the 
appropriate radio button to modify the feed or product 
stream.
2. In the Design Variables list, select the design variable 
associated to the stream you want to edit.
3. In the stream table, select the data set you want to modify.
4. Click the Edit Selected Dataset button. 
You can calculate base shift values using the options in the 
Dataset page or specify the base shift values in the Base 
Shifts page.
Object Description
Feed radio button Enables you to access and modify the composition 
of the feed stream.
Product radio button Enables you to access and modify the composition 
of the product stream.
Design Variables list Enables you to access and modify the data set 
values of the selected variable.
Dataset columns Enables you to specify the selected design variable 
value for the associate data set.
Feed Dataset column Enables you to specify the feed stream 
composition for the associate data set.
This column is only available if the Feed radio 
button is selected.
Product Dataset 
column
Enables you to specify the product stream 
composition for the associate data set.
This column is only available if the Product radio 
button is selected.
Edit Selected Dataset 
button
Enables you to edit the stream composition of the 
selected data set.
Erase All Datasets 
button
Deletes all the stream composition values for all 
data sets.
Change Comp Base 
button
Enables you to change the composition basis of 
the selected data set.8-57
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8-58 Yield Shift Reactor
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ThThe component composition property view appears.
5. In the appropriate cell, enter the composition value for each 
component.
• You can modify the composition basis of the stream by 
selecting the appropriate radio button in the Composition 
Basis group.
• You can click the Erase button to remove all the 
composition values.
• You can click the Normalize button to shift all the 
composition values so that the total value equals 1.
• You can click the Cancel button to exit the component 
composition property view without accepting any of the 
changes made.
6. Click the OK button to accept the modified composition 
values.
To change the composition basis of a data set:
1. In the Data Sets of Design Variables group, select the 
appropriate radio button to modify the feed or product 
stream.
2. In the Design Variables list, select the design variable 
associated to the stream you want to edit.
3. In the stream table, select the data set you want to modify.
4. Click the Change Comp Basis button. 
 Figure 8.408-58
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ThThe composition basis property view appears.
5. Select the composition basis you want by clicking the 
appropriate radio button.
You can click the Cancel button to exit the composition basis 
property view without accepting any of the changes made.
6. Click the Accept button to accept the new selection.
Calculating Component Shift
The following equation is used to calculate the component shift 
value for the dataset of each variable.
where:
 = component shift value for component k of 
dataset j
 = yield value for component k of dataset j+1
 = yield value for component k of dataset j
 = maximum design variable value for dataset j+1
 = minimum design variable value for dataset j
 Figure 8.41
(8.23)comp_shiftk
j yieldk
j 1+ yieldk
j–
input_varj 1+ input_varj–
-------------------------------------------------------------=
comp_shiftk
j
yieldk
j 1+
yieldk
j
input_varj 1+
input_varj8-59
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8-60 Yield Shift Reactor
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ThBase Yields Page
The Base Yields page enables you to specify the base yield 
values of each component in the reactor.  
 Figure 8.42
If you had already specify the yield values in the Design Data 
page, the base yield values in the Base Yield page will appear 
black and is write protected.
You can calculate base yield values using the options in the 
Base page or specify the base yield values in the Base Yield 
page.
Object Description
Use percent 
conversion radio 
button
Enables you to select the percent conversion yield type 
for the reactor calculation.
Use yield only 
radio button
Enables you to select the specify yield value type for 
the reactor calculation.
Base Yield 
column
Enables you to specify the base yield values for the 
components in the reactor.
Conversion [%] 
column
Enables you to specify the conversion percent value for 
the reactor.
This column is only available is the Use percent 
conversion radio button is selected.8-60
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ThBase Shifts Page
The Base Shifts page enables you to specify the shift values for 
the design parameters.  
Total Conversion 
[%]
Enables you to specify in percentage the amount of 
components in the feed stream was converted in the 
reactor.
This column is only available is the Use yield only 
radio button is selected.
Edit Base Yield 
button
Enables you to edit the component base yield values 
for the reactor.
This button is only active if you have not specified any 
yield values in the Design Data tab.
 Figure 8.43
The variables in this page cannot be modified if you have 
already specified the values in the Design Data page.
You can calculate base shift values using the options in the 
Dataset page or specify the base shift values in the Base 
Shifts page.
Object Description
Min row Enables you to specify the minimum value for the 
associate design parameter data set.
Max row Enables you to specify the maximum value for the 
associate design parameter data set.
Current row Displays the current value for the associate design 
parameter data set.
Object Description8-61
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8-62 Yield Shift Reactor
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ThEfficiencies Page
The Efficiencies page enables you to specify the percentage 
efficiency values of the selected design parameters. 
The efficiency value specified in this page is used in Equation 
(8.15) to calculate the total shift values.
Base row Enables you to specify the base value for the 
associate design parameter data set.
Cur_adj row Displays the adjusted current variable value, see 
Equation (8.16).
Base_adj row Displays the adjusted base variable value, see 
Equation (8.17).
Component rows Enables you to specify the component composition 
value for the associate design parameter data set.
Edit Selected Base 
Shift button
Enables you to edit the composition of the selected 
design parameter data set.
Normalize All Base 
Shifts button
Enables you to normalize the base shifts sum to 0.
Erase All Base Shifts 
button
Enables you to delete composition value for all the 
design parameter data sets.
 Figure 8.44
Object Description8-62
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Reactor Operations 8-63
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ThResults Page
The Results page contains the calculated values from the 
specified parameters. The information is split into the following 
pages:
• Yields
• Shift Extents
• Total Extents
Results:Yields Page
The Yields page displays the base yield, total shift, and current 
yield of all the components in the reactor.
 Figure 8.45
 Figure 8.468-63
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8-64 Yield Shift Reactor
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ThResults:Shift Extents Page
The Shift Extents page displays the component composition shift 
values for each data set.
Results:Total Extents Page
The Total Extents page displays the component extent value for 
the base, design parameters, and total extent values.
 Figure 8.47
 Figure 8.488-64
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Th8.3.5 Property Shift Tab
The Property Shift tab contains options to specify the property 
shift of the design variables. These options are split into the 
following pages:
• Properties
• Design Data: Base and Data
• Base Shifts
• Efficiencies
• Results: Shift Extents and Total Extents
Calculating Property Shift
The following equation is used to calculate the property shift:
where:
cur_prop = current property shift value
base_prop = base property value
NV = number of input variables
NRi = number of ranges for each input variable i
effi = efficiency value for design variable i, the values are 
user-specified in the Efficiencies Page
(8.24)
(8.25)
(8.26)
(8.27)
cur_prop base_prop total_shift+=
total_shift cur_adji
j base_adji
j–( ) effi×[ ]
j 0=
NRi
∑
i 0=
NV
∑=
cur_adji
j Max pi
j min, Min pi
j max, cur_valuei,( ),[ ]=
base_adji
j Max pi
j min, Min pi
j max, base_valuei,( ),[ ]=8-65
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8-66 Yield Shift Reactor
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Th = minimum range value of each dataset j from design 
variable i
 = maximum range value of each dataset j from design 
variable i
cur_valuei = current value for design variable i
base_valuei = base value for design variable i
Properties Page
The Properties page enables you to insert or remove yield shift 
properties. 
If the range values are not specified, HYSYS assumes 
negative and positive infinity values for minimum and 
maximum range respectively.
 Figure 8.49
Object Description
Name column Enables you to change the name of the selected 
property.
Value column Enables you to specify the property value.
Unit Type column Enables you to select the property unit type.
pi
j min,
pi
j max,8-66
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ThDesign Data Page
The Design Data page enables you to configure the selected 
design parameter and data set. The options are split into the 
following branches/pages:
• Base
• Datasets 
Insert New 
Property button
Enables you to add a new property.
Remove Selected 
Property button
Enables you to remove the selected property in the 
table.
You can select multiple properties by pressing and 
holding the CTRL or SHIFT key while selecting the 
properties.
 Figure 8.50
Object Description8-67
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8-68 Yield Shift Reactor
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ThDesign Data: Base Page
The Base page enables you to specify the base value for the 
design variables.
Design Data:Datasets Page
The Datasets page enables you to specify the raw data set 
values for the design variables and properties. These property 
values are used to calculate the base shift value.  
 Figure 8.51
 Figure 8.528-68
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ThCalculating Property Shift Values
The following equation is used to calculate the base shift for 
dataset j of each variable for property shift. 
where:
 = base shift value for component k of dataset j
 = property shift value for component k of dataset j+1
 = property shift value for component k of dataset j
 = maximum design variable value for dataset 
j+1
 = minimum design variable value for dataset j
Object Description
Design Variables list Enables you to access and modify the data set 
values of the selected variable.
Dataset columns Enables you to specify the selected design variable 
value and the selected property values for the 
associate data set.
You can calculate base shift values using the options in the 
Dataset page or specify the base shift values in the Base 
Shifts page.
(8.28)
The above equation is used when only raw data is supplied.
base_shiftk
j propk
j 1+ propk
j–
design_varj 1+ design_varj–
--------------------------------------------------------------------=
base_shiftk
j
propk
j 1+
propk
j
design_varj 1+
design_varj8-69
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8-70 Yield Shift Reactor
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ThBase Shifts Page
The Base Shifts page enables you to configure the shift range 
and shift property value for the reactor.  
 Figure 8.53
You cannot modify the values in the Base Shifts page if you 
have already specified the values in the Properties and 
Design Data pages.
You can calculate base shift values using the options in the 
Dataset page or specify the base shift values in the Base 
Shifts page.
Object Description
Min row Enables you to specify the minimum value for the 
associate design parameter data set.
Max row Enables you to specify the maximum value for the 
associate design parameter data set.
Current row Displays the current value for the associate design 
parameter data set.
Base row Enables you to specify the base value for the associate 
design parameter data set.
Cur_adj row Displays the adjusted current variable value, see 
Equation (8.26).
Base_adj row Displays the adjusted base variable value, see 
Equation (8.27).
Properties rows Enables you to specify the shift property value for the 
associate design parameter data set.8-70
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ThEfficiencies Page
The Efficiencies page enables you to specify the percentage 
efficiency values of the selected design parameters.
The efficiency value specified in this page is used in Equation 
(8.25) to calculate the total shift values.
Results Page
The Results page contains the calculated values for the reactor.
 Figure 8.54
 Figure 8.558-71
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8-72 Yield Shift Reactor
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ThThe information is split into the following branches/pages:
• Shift Extents
• Total Extents
Results:Shift Extents Page
The Shift Extents page displays the property shift values 
associated to the design parameters.
Results:Total Extents Page
The Total Extents page displays the property values for the 
base, design parameter, and current.
 Figure 8.56
 Figure 8.578-72
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Th8.3.6 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
8.3.7 Dynamics Tab
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages accessible 
through this tab. 
The Dynamics tab for Yield Shift Reactor operation has only one 
page: Specs.
Specs Page
The Specs page contains the option to set the reactor vessel 
volume.
The PF Specs page is relevant to dynamics cases only.
 Figure 8.58
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.8-73
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8-74 Plug Flow Reactor
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Th8.4 Plug Flow Reactor
The Plug Flow Reactor (PFR), also known as the Tubular Reactor, 
generally consists of a bank of cylindrical pipes or tubes. The 
flow field is modeled as plug flow, implying that the stream is 
radially isotropic (without mass or energy gradients). This also 
implies that axial mixing is negligible.
As the reactants flow the length of the reactor, they are 
continually consumed, hence, there is an axial variation in 
concentration. Since reaction rate is a function of concentration, 
the reaction rate also varies axially (except for zero-order 
reactions).
To obtain the solution for the PFR (axial profiles of compositions, 
temperature, and so forth), the reactor is divided into several 
subvolumes. Within each subvolume, the reaction rate is 
considered to be spatially uniform. A mole balance is done in 
each subvolume j:
 Figure 8.59
(8.29)Fj0 Fj– rj Vd
V
∫+
Njd
dt
-------=8-74
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ThBecause the reaction rate is considered spatially uniform in each 
subvolume, the third term reduces to rjV. At steady state, the 
right side of this balance equals zero, and the equation reduces 
to:
Newton’s Method
The default calculation process for solving the PFR is Newton’s 
method. In this method, the PFR is divided into segments 
(subvolumes) that behave like well-mixed, stirred tank reactors. 
For an adiabatic reactor in the solution step, the outer loop 
converges on enthalpy and temperature, and the inner loop 
converges on composition.
To reduce the convergence time to solve the PFR, you can 
specify the reactor outlet stream temperature and reactor duty 
to eliminate the outer loop calculation. However, to model an 
adiabatic reactor, you must manually converge on the outlet 
stream temperature.
In the inner loop, the program solves the outlet fluid 
composition for an assumed value of outlet fluid temperature 
using a Newton strategy. In this solution strategy, the 
component mass balances are solved using the following 
equation:
where:
Fk,i = kth component’s inlet flowrate
Fk,o = outlet flowrate for the kth component
rk,n = reaction rate of the kth component in nth reaction
(8.30)
(8.31)
Fj Fj0 rjV+=
∑−=
0
,,,
N
nkokjk rVFF  for all k 8-75
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8-76 Plug Flow Reactor
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ThV = volume containing the reactions; in the case of PFR, this 
is the reactor segment volume
rk,n is typically a complex function of the composition of the 
outlet fluid, so the set of equations are non-linear.
In the inner loop, a fixed tolerance of 1.0e-6 is used on the sum 
of residuals for the equations.
The outer loop then converges on the enthalpy of the outlet 
fluid. The new temperature in the outer loop is computed using 
a line-search strategy. The temperature is first bracketed at 
points T1 and T2.
where:
Ho,spec = specified enthalpy of the outlet stream 
Ho,calc = calculated enthalpy of the outlet stream at 
temperature T
Hi,spec = specified enthalpy of the inlet stream
D = specified duty entering the reactor
T = temperature
• If T2 > Tnew > T1 and Tnew - T1 < T2 - Tnew, then Tnew 
becomes the next T1.
• If T2 > Tnew > T1 and Tnew - T1 > T2 - Tnew, then Tnew 
becomes the next T2.
• If Tnew < T1, then Tnew becomes the next T1.
• If Tnew > T2, then Tnew becomes the next T2.
(8.32)
Tnew
HT1
HT1 HT2+
------------------------- T1 T2–( ) T1+=
( )1 , , 1T o spec o calc T
H H H= −
( )2 , , 2T o spec o calc T
H H H= −
, ,o spec i specH H D= +8-76
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ThThe convergence criteria for the outer loop is:
where:
  = outer loop tolerance (default value is 1.0e-5) 
The outer loop tolerance can be changed in the Advanced 
property view of the Reaction set. Refer to the Reactions Set 
Property View in the Aspen HYSYS Simulation Basis Guide 
for more information.
8.4.1 Adding a Plug Flow 
Reactor (PFR)
There are two ways that you can add a PFR to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Reactors radio button.
3. From the list of available unit operations, select Plug Flow 
Reactor.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Plug Flow Reactor icon.
(8.33), ,
, ,
o spec o calc
o spec o calc
H H
H H
δ
−
<
+
δ
Plug Flow Reactor icon8-77
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8-78 Plug Flow Reactor (PFR) Property 
ww
ThThe PFR property view appears.
8.5 Plug Flow Reactor 
(PFR) Property View
The Plug Flow Reactor (PFR) property view contains the 
following tabs:
• Design
• Reactions
• Rating
• Worksheet
• Performance
• Dynamics
 Figure 8.608-78
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Th8.5.1 PFR Design Tab
The Design tab of the PFR contains several pages, which are 
briefly described in the table below.
Connections Page
You can specify the name of the reactor, the feed(s) stream, 
product stream, and energy stream on the Connections page.  
Page Input Required
Connections Attaches the feed and product streams to the reactor. 
Refer to the section below for more information.
Parameters Allows you to specify the parameters for the pressure 
drops and energy streams. 
Heat Transfer Allows you to specify the heat transfer parameters.
User Variables Allows you to create and implement User Variables. 
Notes Allows you to add relevant comments which are 
exclusively associated with the unit operation. 
 Figure 8.61
If you do not provide an energy stream, the operation is 
considered to be adiabatic. 8-79
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ThThe table below describes the objects on the Connections page.
Parameters Page
You can instruct HYSYS on the calculations for the pressure drop 
and heat transfer, and also decide whether the operation is 
included in the calculation on the Parameters page.
Pressure Drop Parameters Group
In the Pressure Drop Parameters group, you can select one of 
the available radio buttons for the determination of the total 
pressure drop across the reactor. 
Object Input Required
Inlets The reactor feed stream.
Outlet The reactor product stream.
Energy 
(Optional)
You are not required to provide an energy stream, however 
under those circumstances HYSYS assumes that the 
operation is adiabatic.
 Figure 8.628-80
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ThThe radio buttons are described in the table below. 
Radio Button Description
User 
Specified 
Select this radio button to specify a pressure drop in the 
Delta P field.
Ergun 
Equation 
HYSYS uses the Ergun equation to calculate the pressure 
drop across the PFR. The equation parameters include 
values which you specify for the PFR dimensions and feed 
streams:
(8.34)
where:
 = pressure drop across the reactor
gc = Newton's-law proportionality factor for the 
gravitational force unit
L = reactor length
 = particle sphericity
Dp = particle (catalyst) diameter
 = fluid density
 = superficial or empty tower fluid velocity
 = void fraction
 = fluid viscosity
If you select the Ergun Equation radio button for a PFR with 
no catalyst (solid), HYSYS sets  = 0.
When you select the Ergun Equation radio button, the Delta P 
field changes colour from blue to black, indicating a value 
calculated by HYSYS.
ΔPgc
L
------------
ϕsDp
ρV2
------------ ε3
1 ε–
----------- 150 1 ε–( )
ϕsDpVρ μ⁄
--------------------------- 1.75+=
ΔP
ϕs
ρ
V
ε
μ
ΔP8-81
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8-82 Plug Flow Reactor (PFR) Property 
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ThDuty Parameters Group
For the PFR heat transfer calculations, you can select one of the 
radio buttons described in the table below.
You can specify whether the energy stream is Heating or Cooling 
by selecting the appropriate radio button. This does not affect 
the sign of the duty stream. Rather, if the energy stream is 
Heating, then the duty is added to the feed. If Cooling is chosen, 
the duty is subtracted.
Heat Transfer Page
The format of the Heat Transfer page depends on your selection 
in the SS Duty Calculation Option group. There are two radio 
buttons:
• Formula 
• Direct Q Value
Radio Button Description
Formula HYSYS calculates the energy stream duty after you specify 
further heat transfer information on the Heat Transfer 
Page. The two fields below the radio buttons show the 
Energy Stream, which is attached on the Connections page, 
and the Calculated Duty value.
Direct Q 
Value
You can directly specify a duty value for the energy stream.
Your selection in the SS Duty Calculation Option group is also 
transferred to the Heat Transfer group on the Parameters 
page.8-82
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ThDirect Q Value Option
When you select the Direct Q Value radio button, the Heat 
Transfer group appears. It consists of three objects, which are 
described in the table below. 
Formula Option
When you select the Formula radio button, you instruct HYSYS 
to rigorously calculate the duty of each PFR subvolume using 
local heat transfer coefficients for the inside and the outside of 
each PFR tube using Equation (8.35) and Equation (8.36).       
 Figure 8.63
Object Description
Energy Stream The name of the duty stream.
Duty The duty value to be specified in the energy stream.
Heating \ 
Cooling
Selecting one of these radio buttons does not affect the 
sign of the duty stream. Rather, if the energy stream is 
Heating, then the duty is added to the feed. If Cooling is 
chosen, the duty is subtracted.
 Figure 8.648-83
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8-84 Plug Flow Reactor (PFR) Property 
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Thwhere:
Qj = heat transfer for subvolume j
Uj = overall heat transfer coefficient for subvolume j
A = surface area of the PFR tube
Tbulkj = bulk temperature of the fluid
Toutj = temperature outside of the PFR tube (utility fluid) 
where:  
U = overall heat transfer coefficient
hout = local heat transfer coefficient for the outside (utility 
fluid)
hw = local heat transfer coefficient inside the PFR tube
 = heat transfer term for the tube wall (ignored in 
calculations)
For the Formula option, you must have an energy stream 
attached to the PFR. You cannot use this option while 
operating adiabatically.
Qj = UjA(Tbulkj - Toutj) (8.35)
Resistance of the tube wall to heat transfer is neglected.
(8.36)
The final term in Equation (8.36), which represents the 
thickness of the tube divided by the thermal conductivity of 
the tube material, is deemed negligible and is ignored in the 
PFR calculations.
1
U
--- 1
hout
--------- 1
hw
-----
xw
km
-----+ +=
xw
km
-----8-84
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ThIn each subvolume, heat is being transferred radially between 
the PFR fluid and the utility fluid. The two groups available on 
the Heat Transfer page allow you to specify parameters which 
are used in the determination of the duty.
Heat Medium Side Heat Transfer Infos Group
In the Heat Medium Side Heat Transfer Infos group, you can 
modify the parameters which are used to calculate the duty (Qj) 
for the outside of each PFR subvolume.  
The table below describes the parameters.
The equation used to determine the temperature of the utility 
 Figure 8.65
If you specify a heat flow on the Energy Stream property 
view and select the Formula radio button on the Heat 
Transfer page, inconsistencies appear in the solution. You 
cannot specify a duty and have HYSYS calculate the same 
duty.
Parameter
Formula 
Variable
Input Required
Wall Heat 
Transfer 
Coefficient
hout Specify a value for the local heat transfer 
coefficient. Since the UA value, in this case the U 
being the local heat transfer coefficient, is 
constant, changes made to the specified length, 
diameter or number of tubes (on the Dimensions 
page) affects hout.
Mole Flow m Molar flow of the energy stream utility fluid.
Heat Capacity Cp Heat capacity of the energy stream utility fluid.
Inlet 
Temperature
T The temperature of the utility fluid entering the 
PFR.
Calculated Duty Qj Duty calculated for each PFR subvolume.8-85
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8-86 Plug Flow Reactor (PFR) Property 
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Thfluid entering each subvolume j is:
Tube Side Heat Transfer Info Group
In the Tube Side Heat Transfer Info group, you can select the 
method for determining the inside local heat transfer coefficient 
(hw) by selecting one of the radio buttons and specifying the 
required parameters. The radio buttons are described in the 
table below. 
(8.37)Qj mCp Tj Tj 1+–( )=
Radio Button Description View
User Specify a value for the local heat transfer coefficient in 
the User Specified input field.
Empirical Specify coefficients for the empirical equation which 
relates the heat transfer coefficient to the flowrate of 
the PFR fluid via the following equation:
(8.38)
You can also choose the basis for the equation as 
Molar, Mass or Volume.
Standard Specify coefficients for the calculation of the Nusselt 
number, which is then used to calculate the local heat 
transfer coefficient:
(8.39)
(8.40)
hw A FlowB×=
Nu A ReB× PrC×=
hw
Nukg
Dp
-----------=
HYSYS uses the following defaults:
• A = 1.6
• B = 0.51
• C = 0.338-86
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
8.5.2 Reactions Tab
You can add a reaction set to the PFR on the Reactions tab. 
Notice that only Kinetic, Heterogeneous Catalytic, and Simple 
Rate reactions are allowed in the PFR. The tab contains the 
following pages: 
• Overall
• Details
• Results
Overall Page
You can specify the reaction set and calculation information on 
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.8-87
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Ththe Overall page.
The Overall page consists of three groups:
• Reaction Info
• Integration Information
• Catalyst Data
Reaction Info Group
In the Reaction Info group, you specify the following 
information:
• The reaction set to be used.
• The segment initialization method.
 Figure 8.66
 Figure 8.678-88
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ThFrom the Reaction Set drop-down list, select the reaction set 
you want to use for the PFR.    
As described earlier in this section, the PFR is split into 
segments by the reactor solver algorithm; HYSYS obtains a 
solution in each segment of the reactor. The segment reactions 
may be initialized using the following methods:
Integration Information Group
The Integration Information group consists of three fields:
• Number of Segments
• Minimum Step Fraction
• Minimum Step Length
The reaction set you want to use must be attached to the 
fluid package you are using in this environment.
Initialization 
Option
Description
Current Initializes from the most recent solution of the current 
segment.
Previous Initializes from the most recent solution of the previous 
segment.
Re-init Re-initializes the current segment reaction calculations.
 Figure 8.688-89
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ThThe table below briefly describes the fields.  
During each segment calculation, HYSYS attempts to calculate a 
solution over the complete segment length. If a solution cannot 
be obtained, the current segment is halved, and HYSYS 
attempts to determine a solution over the first half of the 
segment. The segment continues to be halved until a solution is 
obtained, at which point the remaining portion of the segment is 
calculated. If the segment is divided to the point where its 
length is less than the minimum step length, calculations stop.
Field Description
Number of 
Segments
The number of segments you want to split the PFR into.
Minimum 
Step Fraction
The minimum fraction an unresolved segment splits too.
The length of each segment stays constant during the 
calculations. However, if a solution cannot be obtained for 
an individual segment, it is divided into smaller sections 
until a solution is reached. This does not affect the other 
segments.
Minimum 
Step Length
The product of the Reactor Length and the Minimum Step 
Fraction.8-90
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ThCatalyst Data Group
If you specified a void fraction less than one on the Rating tab, 
the Catalyst Data group appears.
The following information must be specified: 
 Figure 8.69
Field Description
Particle 
Diameter 
The mean diameter of the catalyst particles. The default 
particle diameter is 0.001 m.
Particle 
Sphericity 
This is defined as the surface area of a sphere having the 
same volume as the particle divided by the surface area of 
the particle. A perfectly spherical particle has a sphericity of 
1.The Particle Diameter and Sphericity are used to calculate 
the pressure drop (in the Ergun pressure drop equation) if 
it is not specified.
Solid Density The density of the solid portion of the particle, including the 
catalyst pore space (microparticle voidage).This is the mass 
of the particle divided by the overall volume of the particle, 
and therefore includes the pore space.The default is 2500 
kg/m3.
Bulk Density Equal to the solid density multiplied by one minus the void 
fraction.
(8.41)
where:
 = bulk density
 = solid density
 = macroparticle voidage (void fraction)
Solid Heat 
Capacity
Used to determine the solid enthalpy holdup in 
dynamics.The bulk density is also required in this 
calculation.
ρb ρs 1 εma–( )=
ρb
ρs
εma8-91
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ThDetails Page
You can manipulate the reactions attached to the selected 
reactions set on the Details page.
The Details page consists of three objects, which are briefly 
described in the table below.
Stoichiometry Group
When you select the Stoichiometry radio button, the 
Stoichiometry group appears. The Stoichiometry group allows 
you to examine the components involved in the currently 
selected reaction, their molecular weights as well as their 
stoichiometric coefficients.
 Figure 8.70
Object Description
Reaction Allows you to select the reaction you want to use in the 
reactor.
View 
Reaction
Opens the Reaction property view for the selected reaction. 
This allows you to edit the reaction. Editing the Reaction 
propety view affects all other implementations of the 
selected reaction.
Specifics Toggles between the Stoichiometry group or the Basis 
group (the groups are described in the following sections).8-92
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Th 
The Balance Error (for the reaction stoichiometry) and the 
Reaction Heat (Heat of Reaction at 25°C) are also shown for the 
current reaction. 
Basis Group
When you select the Basis radio button, the Basis group 
appears. In the Basis group, you can view the base component, 
and the rate expression parameters.
You can make changes to these parameters, however these 
changes only affect the current implementation of the reaction 
and are not affected by other reactors using the reaction set or 
reaction.
 Figure 8.71
To affect change in the reaction over the entire simulation 
you must click the View Reaction button and make the 
changes in the Reaction property view.
 Figure 8.728-93
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ThView Reaction Button
Click the View Reaction button to open the Reaction property 
view of the reaction currently selected in the Reaction drop-
down list.   
Results Page
The Results page displays the results of a converged reactor. 
The page consists of the Reaction Balance group which contains 
two radio buttons: 
• Reaction Extents
• Reaction Balance
The type of results displayed varies depending on the radio 
button selected.
Any changes made to the Conversion Reaction property view 
are made globally to the selected reaction and any reaction 
sets which contain the reaction.
You can change the specified conversion for a reaction 
directly on this page.8-94
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ThReaction Extents
When you select the Reaction Extents radio button, the Results 
page appears as shown in the figure below.
The Reaction Balance group displays the following results for a 
converged reactor:
 Figure 8.73
Result Field Description
Actual % 
Conversion 
Displays the percentage of the base component in 
the feed stream(s) which has been consumed in the 
reaction.
Base Component The reactant to which the conversion is applied.
Rxn Extent Lists the molar rate consumption of the base 
component in the reaction divided by its 
stoichiometirc coefficient appeared in the reaction.8-95
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8-96 Plug Flow Reactor (PFR) Property 
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ThReaction Balance
When you select the Reaction Balance radio button, the option 
provides an overall component summary for the PFR. All 
components which appear in the connected component list are 
shown. 
Values appear after the solution of the reactor has converged. 
The Total Inflow rate, the Total Reacted rate and the Total 
Outflow rate for each component are provided on a molar basis. 
Negative values indicate the consumption of a reactant, while 
positive values indicate the appearance of a product.
8.5.3 Rating tab
The Rating tab contains the following pages: 
• Sizing
• Nozzles
 Figure 8.74
Any changes made to the global reaction affect all reaction 
sets to which the reaction is attached, provided local 
changes have not been made.8-96
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ThSizing Page
You can specify the tube dimensions and the tube packing 
information on the Sizing page.
Tube Dimensions
For the tube dimensions, you need to specify any three of the 
following four parameters:
When three of these dimensions are specified, the fourth is 
automatically calculated. Notice that the Total Volume refers to 
the combined volumes of all tubes.
By default, the number of tubes is set to 1. Although the 
number of tubes is generally specified, you can set this 
 Figure 8.75
Tube Dimension Description
Total Volume Total volume of the PFR.
Length Total length of the individual tube.
Diameter Diameter of an individual tube.
Number of tubes. Total number of tubes required. This is always 
calculated to the nearest integer value.8-97
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8-98 Plug Flow Reactor (PFR) Property 
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Thparameter as a calculated value by selecting the Number of 
Tubes field and pressing the DELETE key. The number of tubes 
are always calculated as an integer value. It is possible to obtain 
a rounded value of 0 as the number of tubes, depending on 
what you specified for the tube dimensions. In this case, you 
have to re-specify the tube dimensions.
The Tube Wall Thickness can also be specified.
Tube Packing
The Tube Packing group consists of two fields: 
• Void Fraction 
• Void Volume
The Void Fraction is by default set to 1, in which case there is no 
catalyst present in the reactor. The resulting Void Volume is 
equal to the reactor volume.
At Void Fractions less than 1, the Void Volume is the product of 
the Total Volume and Void Fraction. In this case, you are also 
required to provide information on the Overall page of the 
Reactions tab. This information is used to calculate pressure 
drop, reactor heat capacity and spatial velocity of the fluid 
travelling down the reactor.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
The Void Volume is used to calculate the spatial velocity, 
which impacts the rate of reaction.
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.8-98
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Th8.5.4 Work Sheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
8.5.5 Performance Tab
The Performance tab allows you to examine various axial 
profiles in the PFR. The tab contains the following pages, each 
page containing a general type of profile: 
• Conditions
• Flows
• Reaction Rates (Rxn Rates)
• Transport
• Compositions
Each page consists of a table containing the relevant 
performance data and a Plot button which converts the data to a 
graphical form.
The PF Specs page is relevant to dynamics cases only.
 Figure 8.76
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.8-99
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Th 
The data points are taken in the middle of each reactor 
segment, and correspond to the number of reactor segments 
you specified.
Conditions Page
The Conditions page allows you to view a table of the various 
physical parameters: Temperature, Pressure, Vapour Fraction, 
Duty, Enthalpy, Entropy, Inside HTC, and Outside HTC as a 
function of the Reactor Length.
If you click the Plot button, a plot similar to the one shown in the 
figure below appears. It shows the selected Physical parameter 
as a function of the Reactor Length.
The Reactor Length is always plotted on the x-axis.
 Figure 8.778-100
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ThFlows Page
There are four overall flow types which can be viewed in a table 
or plotted as a function of the Reactor Length:
• Material Flow: Molar, Mass, or Volume
• Energy: Heat
If you click the Plot button, the table appears in a graphical 
form. 
Reaction Rates Page
You can view either Reaction Rate or Component Production 
Rate data as a function of the Reactor Length on the Rxn Rates 
page. You can toggle between the two data sets by selecting the 
appropriate radio button.
You can view the data in graphical form by clicking the Plot 
button.
Transport Page
The overall Transport properties appear in a tabular form as a 
function of the Reactor Length on the Transport page.
Transport Properties:
• Viscosity
• Molar Weight
• Mass Density
• Heat Capacity
• Surface Tension
• Z Factor
You can view the data in a graphical form by clicking the Plot 
button. Select the appropriate radio button to display the 
selected plot.
Although only one reaction set can be attached to the PFR, it 
can contain multiple reactions.8-101
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ThCompositions Page
You can view individual component profiles using one of six 
composition bases:
• Molar Flow
• Mass Flow
• Liquid Volume Flow
• Fraction:
- Mole Fraction
- Mass Fraction
- Liquid Volume Fraction
You can display the data in a plot form by clicking the Plot 
button.
8.5.6 Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• Duty
• Stripchart
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab.8-102
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ThSpecs Page
Dynamic Specifications Group
The Dynamic Specifications group consists of eleven objects, 
which are described in the table below.
 Figure 8.78
Objects Description
Initialize from 
Products radio 
button
The composition of the holdup is calculated from a 
weighted average of all products exiting the 
holdup. A PT flash is performed to determine other 
holdup conditions.
Initialize from First 
Feed radio button
The composition of the holdup is calculated from 
the first feed entering the PFR reactor.
Dry Startup radio 
button
The calculations based on the holdup starts with 
no fluid in it.
Steady State radio 
button
Uses steady state results to initialize the holdup.
Single Phase 
checkbox
Allows you to specify a single phase reaction. 
Otherwise HYSYS considers it a vapour-liquid 
reaction.
Laminar Flow 
checkbox
Assumes laminar flow in the PFR.8-103
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ThPressure Flow Relation Group
The Pressure Flow Relation group consists mainly of a table of 
the k values for each segment in the PFR. You can enter your 
own k values into this table or, while you are in Steady State 
mode, you can click the Calculate K’s button and HYSYS 
calculates the k values using the steady state data.
Flow Equation 
checkbox
Uses the flow equation to calculate the pressure 
gradient across the PFR. You are required to either 
estimate k values in steady state (by clicking the 
Calculate K’s button) or specifying your own 
values in the Pressure Flow Relation group.
Fixed Delta P 
checkbox
Assumes a constant pressure drop across the PFR. 
Does not require k values.
PFR Elevation cell The height above ground that the PFR is currently 
positioned.
Lag Rxn 
Temperature 
checkbox
The option is designed to speed up the dynamic 
run for the reaction solver when the run has to 
invoke the steady state reaction solver. 
Mathematically, when you select the Lag Rxn 
Temperature checkbox, the reaction solver 
flashes with the explicit Euler method. Otherwise, 
for a dynamic run, the steady state reaction solver 
always flashes with the implicit Euler methods 
which could be slow with many iterations.
The Lag Rxn Temperature may cause some 
instability due to the nature of the explicit Euler 
method. But it must compromise with the dynamic 
step size.
Enable Explicit 
Reaction Calculation 
checkbox
The Enable Explicit Reaction Calculations is 
defaulted to be used for dynamic run reaction 
solver. The explicit reaction solver is quick, but can 
introduce instability. You can deactivate this 
option. The implicit reaction solver is used instead.
Objects Description8-104
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ThHoldup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup in each phase in the 
PFR. 
The Holdup page consists of two groups:
• Overall Holdup Details group displays the holdup data 
within the PFR operation.
• Segment Holdup Details enables you to select and view 
individual holdup data of all the segments in the PFR 
operation.
 Figure 8.79
Refer to Section 1.3.3 
- Holdup Page for 
more information.8-105
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ThDuty Page
In the Source group, you can choose whether HYSYS calculates 
the duty applied to the vessel from a Direct Q or a Utility.
If you select the Direct Q radio button, you can directly specify 
the duty applied to the holdup in the SP field. 
If you select the Utility radio button, you can specify the flow of 
the utility fluid. The duty is then calculated using the local 
overall heat transfer coefficient, the inlet fluid conditions, and 
the process conditions. The calculated duty is then displayed in 
the SP field or the Heat Flow field.
If you select the Heating radio button, the duty shown in the SP 
field or Heat Flow field is added to the holdup. If you select the 
Cooling radio button, the duty is subtracted from the holdup.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation.
 Figure 8.80
For more information 
regarding how the utility 
option calculates duty, 
refer to Chapter 5 - 
Logical Operations.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.8-106
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Th9  Rotating Operations9-1
9.1  Centrifugal Compressor or Expander.............................................. 2
9.1.1  Theory.................................................................................... 4
9.1.2  Compressor or Expander Property View..................................... 11
9.1.3  Design Tab ............................................................................ 12
9.1.4  Rating Tab............................................................................. 17
9.1.5  Worksheet Tab ....................................................................... 37
9.1.6  Performance Tab .................................................................... 37
9.1.7  Dynamics Tab ........................................................................ 38
9.2  Reciprocating Compressor ........................................................... 48
9.2.1  Theory.................................................................................. 49
9.2.2  Reciprocating Compressor Property View ................................... 55
9.2.3  Design Tab ............................................................................ 56
9.2.4  Rating Tab............................................................................. 61
9.2.5  Worksheet Tab ....................................................................... 62
9.2.6  Performance Tab .................................................................... 62
9.2.7  Dynamics Tab ........................................................................ 63
9.3  Pump ........................................................................................... 63
9.3.1  Theory.................................................................................. 64
9.3.2  Pump Property View ............................................................... 66
9.3.3  Design Tab ............................................................................ 68
9.3.4  Rating Tab............................................................................. 74
9.3.5  Worksheet Tab ....................................................................... 90
9.3.6  Performance Tab .................................................................... 90
9.3.7  Dynamics Tab ........................................................................ 91
9.4  References................................................................................... 95
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9-2 Centrifugal Compressor or 
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Th9.1 Centrifugal 
Compressor or 
Expander
The Centrifugal Compressor operation is used to increase the 
pressure of an inlet gas stream with relative high capacities and 
low compression ratios. Depending on the information specified, 
the Centrifugal Compressor calculates either a stream property 
(pressure or temperature) or a compression efficiency.
A Centrifugal Compressor can also be used to represent a Pump 
operation when a more rigorous pump calculation is required. 
The Pump operation in HYSYS assumes that the liquid is 
incompressible. Therefore, if you want to pump a fluid near its 
critical point (where it becomes compressible), you can do so by 
representing the Pump with a Centrifugal Compressor. The 
Centrifugal Compressor operation takes into account the 
compressibility of the liquid, thus performing a more rigorous 
calculation.
The Expander operation is used to decrease the pressure of a 
high pressure inlet gas stream to produce an outlet stream with 
low pressure and high velocity. An expansion process involves 
converting the internal energy of the gas to kinetic energy and 
finally to shaft work. The Expander calculates either a stream 
property or an expansion efficiency.
There are several methods for the Centrifugal Compressor or 
Expander to solve, depending on what information has been 
specified, and whether or not you are using the compressor’s 
characteristic curves. In general, the solution is a function of 
flow, pressure change, applied energy, and efficiency. The 
Centrifugal Compressor or Expander provides a great deal of 
flexibility with respect to what you can specify and what it then 
calculates. You must ensure that you do not enable too many of 
the solution options or inconsistencies may result.9-2
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ThSome of the features in the dynamic Centrifugal Compressor 
and Expander operations include:
• Dynamic modeling of friction loss and inertia in the 
Centrifugal Compressor or Expander.
• Dynamic modeling which supports shutdown and startup 
behaviour.
• Multiple head and efficiency curves.
• Modeling of Stonewall and Surge conditions of the 
Centrifugal Compressor or Expander. 
• A dedicated surge controller which features quick 
opening capabilities.
• Handling of phase changes that may occur in the unit 
operation (for example Expanders producing liquid).
• Linking capabilities with other rotational equipment 
operating at the same speed with one total power.
Typical Solution Methods
The thermodynamic principles governing the Centrifugal 
Compressor and Expander operations are the same, but the 
direction of the energy stream flow is opposite. Compression 
requires energy, while expansion releases energy.
The operating characteristics curves of a compressor is 
usually expressed as a set of polytropic head and efficiency 
curves made by manufacturers.
Without Curves With Curves
1. Flow rate and inlet pressure are known.
2. Specify outlet pressure.
3. Specify either Adiabatic or Polytropic 
efficiency.
4. HYSYS calculates the required energy, 
outlet temperature, and other efficiency.
1. Flow rate and inlet pressure are known.
2. Specify operating speed.
3. HYSYS uses curves to determine efficiency and 
head.
4. HYSYS calculates outlet pressure, temperature, and 
applied duty.
1. Flow rate and inlet pressure are known.
2. Specify efficiency and duty.
3. HYSYS calculates outlet pressure, 
temperature, and other efficiency.
1. Flow rate, inlet pressure, and efficiency are known.
2. HYSYS interpolates curves to determine operating 
speed and head.
3. HYSYS calculates outlet pressure, temperature, and 
applied duty.9-3
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9-4 Centrifugal Compressor or 
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Th9.1.1 Theory
Steady State
For a Centrifugal Compressor, the isentropic efficiency is given 
as the ratio of the isentropic (ideal) power required for 
compression to the actual power required: 
For an Expander, the efficiency is given as the ratio of the actual 
power produced in the expansion process to the power produced 
for an isentropic expansion:
For an adiabatic Centrifugal Compressor and Expander, HYSYS 
calculates the centrifugal compression (or expansion) rigorously 
by following the isentropic line from the inlet to outlet pressure. 
Using the enthalpy at that point, as well as the specified 
efficiency, HYSYS then determines the actual outlet enthalpy. 
From this value and the outlet pressure, the outlet temperature 
is determined.
For a polytropic Centrifugal Compressor or Expander, the path of 
the fluid is neither adiabatic nor isothermal. For a 100% efficient 
process, there is only the condition of mechanical reversibility. 
For an irreversible process, the polytropic efficiency is less than 
100%. Depending on whether the process is an expansion or 
compression, the work determined for the mechanically 
reversible process is multiplied or divided by an efficiency to 
(9.1)
Throughout this chapter you will see “isentropic” and 
“adiabatic” used interchangeably. This is because they are 
the same.
(9.2)
Efficiency %( )
Power Requiredisentropic
Power Requiredactual
----------------------------------------------------------------- 100%×=
Efficiency %( )
Fluid Power Producedactual
Fluid Power Producedisentropic
----------------------------------------------------------------------------------- 100%×=9-4
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Thgive the actual work. The form of the polytropic efficiency 
equations are the same as Equation (9.1) and Equation 
(9.2).
Notice that all intensive quantities are determined 
thermodynamically, using the specified Property Package. In 
general, the work for a mechanically reversible process can be 
determined from:.
where:  
W = work
V = volume
dP = pressure difference
As with any unit operation, the calculated information depends 
on the information which is specified by the user. In the case 
where the inlet and outlet pressures and temperatures of the 
gas are known, the ideal (isentropic) power of the Operation is 
calculated using one of the above equations, depending on the 
Centrifugal Compressor or Expander type. The actual power is 
equivalent to the heat flow (enthalpy) difference between the 
inlet and outlet streams.
• For the Centrifugal Compressor:
where the efficiency of the Centrifugal Compressor is 
then determined as the ratio of the isentropic power to 
the actual power required for compression.
• For the Expander:
The efficiency of the Expander is then determined as the 
ratio of the actual power produced by the gas to the 
isentropic power.
(9.3)
Power Requiredactual = Heat Flowoutlet - Heat 
Flowinlet
(9.4)
Power Producedactual = Heat Flowinlet - Heat 
Flowoutlet
(9.5)
W V Pd∫=9-5
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9-6 Centrifugal Compressor or 
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ThIn the case where the inlet pressure, the outlet pressure, the 
inlet temperature and the efficiency are known, the isentropic 
power is once again calculated using the appropriate equation. 
The actual power required by the Centrifugal Compressor 
(enthalpy difference between the inlet and outlet streams) is 
calculated by dividing the ideal power by the compressor 
efficiency. The outlet temperature is then rigorously determined 
from the outlet enthalpy of the gas using the enthalpy 
expression derived from the property method being used. For an 
isentropic compression or expansion (100% efficiency), the 
outlet temperature of the gas is always lower than the outlet 
temperature for a real compression or expansion.
Dynamic
An essential concept associated with the Centrifugal Compressor 
and Expander operations is the isentropic and polytropic power. 
The calculation of these parameters and other quantities are 
taken from “Compressors and Exhausters - Power Test Codes” 
from the American Society of Mechanical Engineers. 
The isentropic or polytropic power, W, can be calculated from: 
where:  
n = volume exponent
CF = correction factor
P1 =pressure of the inlet stream
P2 = pressure of the exit stream
= density of the inlet stream
F1 =molar flow rate of the inlet stream
MW = molecular weight of the gas
(9.6)W F1 MW( ) n
n 1–
-----------⎝ ⎠
⎛ ⎞CF
P1
ρ1
-----⎝ ⎠
⎛ ⎞ P2
P1
-----⎝ ⎠
⎛ ⎞
n 1–
n
-----------⎝ ⎠
⎛ ⎞
1–×=
ρ19-6
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ThIsentropic power is calculated by defining the volume exponent 
as:
where:  
 = density of the exit stream corresponding to the inlet 
entropy
Polytropic power is calculated by defining the volume exponent 
as:
where:  
 = density of the exit stream
The correction factor is calculated as:
where:  
 = enthalpy of the exit stream corresponding to the inlet 
entropy
h1 = enthalpy of the inlet stream
An isentropic flash is performed to calculate the values of  
and .
HYSYS calculates the compression (or expansion) rigorously by 
following the isentropic line from the inlet to the exit pressure. 
The path of a polytropic process is neither adiabatic nor 
isothermal. The only condition is that the polytropic process is 
reversible.
(9.7)
(9.8)
(9.9)
n
P2 P1⁄( )ln
ρ'2 ρ1⁄( )ln
--------------------------=
ρ′2
n
P2 P1⁄( )ln
ρ2 ρ1⁄( )ln
--------------------------=
ρ2
CF
h'2 h1–
n
n 1–
-----------⎝ ⎠
⎛ ⎞ P2
ρ'2
------
P1
ρ1
-----–⎝ ⎠
⎛ ⎞
------------------------------------------=
h′2
h′2
ρ′29-7
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9-8 Centrifugal Compressor or 
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ThEquations Used
The Centrifugal Compressor equations are used for the 
Centrifugal Compressor. The Expander equations are used for 
the Expander.
Compressor Efficiencies
The Adiabatic and Polytropic Efficiencies are included in the 
Centrifugal Compressor calculations. An isentropic flash (Pin and 
Entropyin) is performed internally to obtain the ideal (isentropic) 
properties.
Expander Efficiencies
For an Expander, the efficiencies are parts of the Expander 
calculations, and an isentropic flash is performed as well. The 
flash is done on the Expander fluid, and the results are not 
stored.
Efficiencies Compressor Expander
Adiabatic
Polytropic
where: where:
Work Required ideal( )
Work Required actual( )
----------------------------------------------------------
Hout Hin–( )
ideal( )
Hout Hin–( )
actual( )
-------------------------------------------------------=
Work Produced actual( )
Work Produced ideal( )
-----------------------------------------------------------
Hout Hin–( )
actual( )
Hout Hin–( )
ideal( )
-------------------------------------------------------=
Pout
Pin
-----------
⎝ ⎠
⎜ ⎟
⎛ ⎞
n 1–
n
-----------⎝ ⎠
⎛ ⎞
1– n
n 1–( )
----------------⎝ ⎠
⎛ ⎞ k 1–
k
-----------⎝ ⎠
⎛ ⎞××
Pout
Pin
-----------
⎝ ⎠
⎜ ⎟
⎛ ⎞
k 1–
k
-----------⎝ ⎠
⎛ ⎞
1–
----------------------------------------------------------------------------------------------------------- AdiabaticEff×
n
Pout Pin⁄( )log
ρout actual, ρin⁄( )log
---------------------------------------------------------=
k
Pout Pin⁄( )log
ρout ideal, ρin⁄( )log
------------------------------------------------------=
Pout
Pin
-----------
⎝ ⎠
⎜ ⎟
⎛ ⎞
k 1–
k
-----------⎝ ⎠
⎛ ⎞
1–
Pout
Pin
-----------
⎝ ⎠
⎜ ⎟
⎛ ⎞
n 1–
n
-----------⎝ ⎠
⎛ ⎞
1– n
n 1–( )
----------------⎝ ⎠
⎛ ⎞ k 1–
k
-----------⎝ ⎠
⎛ ⎞××
----------------------------------------------------------------------------------------------------------- AdiabaticEff×
n
Pout Pin⁄( )log
ρout actual, ρin⁄( )log
---------------------------------------------------------=
k
Pout Pin⁄( )log
ρout ideal, ρin⁄( )log
------------------------------------------------------=9-8
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ThCompressor Heads
The Adiabatic and Polytropic Heads are performed after the 
Centrifugal Compressor calculations are completed, only when 
the Results page of the Centrifugal Compressor is selected. The 
Work Required (actual) is the compressor energy stream (heat 
flow). The Polytropic Head is calculated based on the ASME 
method (“The Polytropic Analysis of Centrifugal Compressors”, 
Journal of Engineering for Power, J.M. Schultz, January 1962, p. 
69-82).
where: 
H = mass enthalpy
out = product discharge
in = feed stream
P = pressure
 = mass density
n = polytropic exponent
 k = isentropic exponent
Efficiencies Compressor Expander
ρ
9-9
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9-10 Centrifugal Compressor or 
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ThExpander Heads
The Adiabatic and Polytropic Heads are performed after the 
Expander calculations are completed, only when the Results 
page of the Expander is selected. The Work Produced (actual) is 
the Expander energy stream (heat flow). 
Head Compressor Expander
Adiabatic
Polytropic
where: where:
where: 
H = mass enthalpy
out = product discharge
in = feed stream
P = pressure
 = mass density
f = polytropic head factor
n = polytropic exponent
 k = isentropic exponent
Work Required actual( )
MassFlowRate
---------------------------------------------------------- AdiabaticEff 1
g gc⁄( )
-----------------××
Work Produced actual( )
MassFlowRate
----------------------------------------------------------- 1
AdiabaticEff
---------------------------------- 1
g gc⁄( )
-----------------××
f n
n 1–
-----------⎝ ⎠
⎛ ⎞
Pout
ρout actual,
------------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞ Pin
ρin
--------
⎝ ⎠
⎜ ⎟
⎛ ⎞
–×× 1
g gc⁄( )
-----------------×
f
Hout ideal, Hin–
k
k 1–
-----------⎝ ⎠
⎛ ⎞
Pout
ρout ideal,
---------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞ Pin
ρin
--------
⎝ ⎠
⎜ ⎟
⎛ ⎞
–×
----------------------------------------------------------------------------------=
n
Pout Pin⁄( )log
ρout actual, ρin⁄( )log
---------------------------------------------------------=
k
Pout Pin⁄( )log
ρout ideal, ρin⁄( )log
------------------------------------------------------=
f n
n 1–
-----------⎝ ⎠
⎛ ⎞
Pout
ρout actual,
------------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞ Pin
ρin
--------
⎝ ⎠
⎜ ⎟
⎛ ⎞
–××– 1
g gc⁄( )
-----------------×
f
Hout ideal, Hin–
k
k 1–
-----------⎝ ⎠
⎛ ⎞
Pout
ρout ideal,
---------------------------
⎝ ⎠
⎜ ⎟
⎛ ⎞ Pin
ρin
--------
⎝ ⎠
⎜ ⎟
⎛ ⎞
–×
----------------------------------------------------------------------------------=
n
Pout Pin⁄( )log
ρout actual, ρin⁄( )log
---------------------------------------------------------=
k
Pout Pin⁄( )log
ρout ideal, ρin⁄( )log
------------------------------------------------------=
ρ
9-10
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Th9.1.2 Compressor or Expander 
Property View
There are two ways that you can add a Compressor or Expander 
to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Rotating Equipment radio button.
3. From the list of available unit operations, select 
Compressor or Expander.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Compressor icon or Expander icon. 
The Compressor or Expander property view appears.
 Figure 9.1
Compressor icon
Expander icon9-11
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9-12 Centrifugal Compressor or 
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Th9.1.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Links
• User Variables
• Notes
Connections Page
The figure below shows the Connections page for the Centrifugal 
Compressor property view. 
The Connections page allows you to specify the name of the 
operation, as well as the inlet stream, outlet stream, and energy 
stream. 
 Figure 9.2
The information required on the Connections page of the 
Expander is identical; the only difference is that the 
Expander icon is shown rather than the Compressor icon.9-12
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ThParameters Page
You can specify the duty of the attached energy stream on the 
Parameters page, or allow HYSYS to calculate it.
The adiabatic and polytropic efficiencies appear on this page as 
well.   
The Parameters page for the Compressor and the Expander are 
similar. However, the following items are not available for the 
Expander:
• Operating Mode group 
• Multiple MW Curves in the Curve Input Option group
In the Operating Mode group, you can switch between a 
Centrifugal and Reciprocating Compressor by selecting the 
corresponding radio button. 
If you choose the Centrifugal radio button, the radio buttons in 
the Curve Input Option group are enabled. 
 Figure 9.3
You can specify only one efficiency, either adiabatic or 
polytropic. If you specify one efficiency and a solution is 
obtained, HYSYS back calculates the other efficiency, using 
the calculated duty and stream conditions.9-13
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9-14 Centrifugal Compressor or 
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ThIn the Curve Input Option group the following radio buttons are 
available:
• Select the Single Curve radio button to model your 
compressor with a single pair of head vs. flow and 
efficiency vs. flow curves.
• Select the Multiple MW Curves radio button if you have 
a set of curves that describe the compressor 
performance as a function of the flowing gas molecular 
weight (MW).
• Select the Multiple IGV Curves radio button if you have 
a set of curves that describe the compressor 
performance as a function of inlet guide vane (IGV) 
position.
Links Page
Compressors and expanders modeled in HYSYS can have shafts 
that are physically connected to the unit operation. Linking 
compressors and expanders in HYSYS means the:
• Speed of each linked unit operation is the same.
• Sum of the duties of each linked Compressor or 
Expander and the total power loss equals zero.  
The Single Curve radio button still allows multiple curves as 
a function of speed, but not MW or IGV position.
When you select Multiple IGV Curves radio button, the 
current inlet guide vane position is specified during the 
operation of the compressor.
The rotational linker operates both in Steady State and 
Dynamic mode.
It is not significant which order the Compressors or 
Expanders are linked. The notion of upstream and 
downstream links is arbitrary and determined by the user.9-14
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ThA list of available compressors or expanders can be displayed by 
clicking the down arrow  in the Downstream Link field. In 
most cases, one additional specification for any of the linked 
operations is required to allow the simulation case to completely 
solve. 
Ideally, you should specify one of the following for any of the 
linked unit operations.
• Duty
• Speed
• Total Power Loss
It is also possible to link an Expander to a Compressor, and use 
the Expander to generate kinetic energy to drive the 
Compressor. If this option is chosen, the total power loss is 
typically specified as zero.
 Figure 9.4
The Gear Ratio field displays the ratio of the speed from 
the next linked operation divided by the speed of the 
current pump.
Select the Dynamic Specification checkbox to specify the total 
power loss (or power gain by entering a negative value) for the 
linked operation.
You can ignore this option in Steady State mode.9-15
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9-16 Centrifugal Compressor or 
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ThDynamics Mode
In Dynamics mode, at least one curve must be specified in the 
Curves page of the Rating tab for each linked unit operation. 
Ideally, a set of linked compressor or expanders should only 
have the Use Characteristic Curves checkbox selected in the 
Specs page of the Dynamics tab. In addition, the total power 
loss for the linked operations should be specified. Usually, total 
power input to the linked compressors or expanders is 
calculated in a Spreadsheet operation and specified by you in 
the Total Power Loss field.
If you want to provide the total power input to a set of linked 
compressors or expanders, the total power input to the linked 
operations is defined in terms of a total power loss. The 
relationship is as follows:
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
(9.10)Total Power Input - Total Power Loss=
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.9-16
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Th9.1.4 Rating Tab
The Rating tab contains following pages:
• Curves
• Flow Limits
• Nozzles
• Inertia
Curves Page
One or more Centrifugal Compressor or Expander curves can be 
specified on the Curves page. 
You can create adiabatic or polytropic plots for values of 
efficiency and head. The efficiency and head for a specified 
speed can be plotted against the capacity of the Centrifugal 
Compressor or Expander. Multiple curves can be plotted to show 
the dependence of efficiency and head on the speed of 
Centrifugal Compressors or Expanders. 
The Nozzles page is only visible if you have the HYSYS 
Dynamics license.
 Figure 9.59-17
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9-18 Centrifugal Compressor or 
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ThIf you do not use curves, specify four of the following variables; 
HYSYS will calculate the fifth variable and the duty:
• Inlet Temperature
• Inlet Pressure
• Outlet Temperature
• Outlet Pressure
• Efficiency
It is assumed that you have specified the composition and flow.
Single MW (Molecular Weight)
If you choose the Single Curve radio button on the Parameters 
page of the Design Tab, the only group visible on the Curves 
page is the Compressor Curves group. 
 Figure 9.6
This option is only relevant for compressors and not 
expanders.9-18
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ThEntering Curve Data
The following are steps to add a curve to the compressor or 
expander:
1. Select either the Adiabatic or Polytropic radio button in 
the Efficiency group. This determines the basis of your input 
efficiency values. 
The efficiency type must be the same for all input curves.
2. Click the Add Curve button and the Curve property view 
appears. 
3. You can specify the following data in the Curve property 
view. 
4. Click the Close icon  to return to the Curves page.
5. Select the corresponding Activate checkbox to use that 
curve in calculations.
 Figure 9.7
Curve Data Description
Name Name of the curve.
Speed The rotational speed of the Centrifugal Compressor or 
Expander. This is optional if you specify only one curve.
HYSYS can interpolate values for the efficiency and 
head of the Centrifugal Compressor or Expander for 
speeds that are not plotted. 
Flow Units/Head 
Units
Units for the flow and head.
Flow/Head/% 
Efficiency
One row of data is equivalent to one point on the 
curve. For better results, you should enter data for at 
least three (or more) points on the curve.9-19
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9-20 Centrifugal Compressor or 
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Th6. For each additional curve, repeat steps #2 to #5.
7. Click the Enable Curves checkbox.
You can remove a specific curve from the calculation by clearing 
its Activate checkbox.
HYSYS uses the curve(s) to determine the appropriate efficiency 
for your operational conditions. If you specify curves, ensure the 
efficiency values on the Parameters page are empty or a 
consistency error will be generated.
Once a curve has been created, the following four buttons on 
the Curves page are enabled:
• View Curve. Allows you to view or edit your input data 
in the Curve property view.
• Delete Curve. Allows you to delete the selected curve 
from the simulation.
• Clone Curve. Allows you to duplicate an existing curve.
• Plot Curves. Allows you to view a graph of activated 
curves.
You can access the Curve property view of an existing curve by 
clicking the View Curve button or by double-clicking the curve 
name.
Deleting Curve Data
The following are two ways you can delete information within a 
curve:
1. Double-click the curve name to open the Curve property 
view.
2. Highlight the data you want to delete and click the Erase 
Selected button.
OR
1. Select the curve within the table and click the View Curve 
button.
2. Click the Erase All button to delete all of the information 
within the Curve property view.9-20
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Rotating Operations 9-21
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ThSingle Curve
When you have a single curve, the following combinations of 
input allow the operation to completely solve (assuming the feed 
composition and temperature are known):
• Inlet Pressure and Flow Rate
• Inlet Pressure and Duty
• Inlet Pressure and Outlet Pressure
• Inlet Pressure and Efficiency corresponding to the Curve 
type (for example, if the Curve is Adiabatic you need to 
provide an Adiabatic Efficiency).
Multiple Curves
If multiple curves have been installed, an operating speed is 
specified on the Curves page, and one of the multiple curves’ 
speed equals the operating speed, then only the curve with the 
corresponding speed is used. For example, if you provide curves 
for two speeds (1000/min and 2000/min), and you specify an 
operating speed of 1000/min, then only the curve with the 
speed of 1000/min is used within the calculation.
If multiple curves have been installed, an operating speed has 
been specified, and none of the multiple curves’ speed equals 
the operating speed, then all of the curves will be used within 
the calculation. For example, if you provide curves for two 
speeds (1000/min and 2000/min), and you specify an operating 
speed of 1500/min, HYSYS interpolates between the two curves 
to obtain the solution. Conversely, if you specify an operating 
speed outside the range of speeds provided by the curves, 
HYSYS uses an extrapolation method to obtain the solution. 
Currently, HYSYS supports both Linear and Quadratic 
extrapolation methods and the user has the option to pick which 
method to use for extrapolation. Linear extrapolation method is 
set as the default option and is highly encouraged since 
extrapolation in general will yield unpredictable results, 
especially when one does not know the actual form of the data.
If multiple curves are used, you need to provide:
• Feed Composition
• Pressure9-21
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9-22 Centrifugal Compressor or 
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Th• Temperature
• Inlet Flow Rate
• Only one of the following variables:
- Duty
- Outlet Pressure
- Operating Speed
HYSYS then calculates the other two variables.
Dynamics Mode
In order to run a stable and realistic dynamics model, HYSYS 
requires you to input reasonable curves. If compressors or 
expanders are linked, it is a good idea to ensure that the curves 
plotted for each unit operation span a common speed and 
capacity range. 
Typical Compressor and Expander curves are plotted in Figure 
9.8 and Figure 9.9.
 Figure 9.89-22
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Rotating Operations 9-23
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ThFor an Expander, the head is only zero when the speed and 
capacity are zero.
Multiple MW (Molecular Weight)
The Multiple MW (molecular weight) option is for more advanced 
users of HYSYS. This option allows the performance of the 
compressor to vary with the flowing gas molecular weight based 
upon the performance map you specified.
When you choose the Multiple MW Curves radio button on the 
Parameters page of the Design tab, the MW Curve Collections 
group and the Plot All Collections checkbox are added to the 
Curves page.
 Figure 9.9
This option is only relevant for compressors and not 
expanders.9-23
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9-24 Centrifugal Compressor or 
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ThThe following is a brief description of the fields and buttons 
found within the MW Curve Collections group. 
 Figure 9.10
Fields Description
MW Curve 
Collections list
Displays the list of curve collection available in the 
unit operation. Each curve collection contains a set of 
data curves at a particular molecular weight.
Curve Collection 
name
Allows you to rename the selected curve collection in 
the list.
Design MW The Design MW is the design average molecular 
weight for the compressor. Its default value is the 
same as the value for the Actual MW. 
This value is only used as a reference point and does 
not affect the Compressor calculation.
The Plot All Collections checkbox is useful if you want to see all the 
curves for all the curve collection (in the compressor) appear in one 
plot. This is particularly useful if all the curves data is based on one 
speed.9-24
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Rotating Operations 9-25
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ThCreating Multiple Curve Collections
The following are methods on how you can create multiple curve 
collections:
1. Enter the data for the curve(s). All of these values will be 
stored under a curve collection named CurveCollection-1.
2. Click the Set Simple Curves button.
3. Two hypothetical curve collections will appear (named 
CurveCollection-2 and CurveCollection-3). These two 
new collections will provide you with rough data for curves 
generated with lighter or heavier components. These 
estimated values are based on the values entered for 
CurveCollection-1.
Curve MW Each curve collection has its corresponding set of 
curves at a particular molecular weight. 
Actual MW This value is calculated by HYSYS. The field displays 
the actual MW of the stream within your case.
The following are descriptions of three potential 
operating situations:
• If the Actual MW is the same as the Design MW, it 
means the compressor is operating with 
components at your designed MW. 
• If the Actual MW is less than the Design MW 
value, it means the compressor is operating with 
lighter components.
• If the Actual MW is more than the Design MW 
value, it means the compressor is operating with 
heavier components.
Buttons Description
Add Curve 
Collection
Adds another empty curve collection to the MW Curve 
Collections list.
Del. Curve 
Collection
Deletes the selected curve collection in the MW Curve 
Collections list.
Set Simple 
Curves
Creates two more curve collections with curve data based 
on the selected curve collection in the MW Curve Collections 
list.
The data values within the two new curve collections are 
estimated values for testing purposes only. You should 
modify this data accordingly to specify your actual curve 
values.
Fields Description
Refer to Entering Curve 
Data section for more 
information.9-25
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ThOR
1. Enter the data for the curve(s). All of these values will be 
stored under a curve collection.
2. Click the Add Curve Collection button.
3. Repeat step #1 to enter the data for the new curve 
collection.
4. Repeat steps #2 to #3 for each additional curve collection.
Multiple IGV (Inlet Guide Vane)
The Multiple IGV (inlet guide vane) Curves option allows you to 
model a compressor with adjustable guide vanes. The guide 
vanes are modulated to control the capacity of the compressor.
When you choose the Multiple IGV Curves radio button on the 
Parameters page of the Design tab, the IGV Curve Collections 
group and the Plot All Collections checkbox are added to the 
Curves page.
The values given in CurveCollection-2 and CurveCollection-3 
are for testing purposes only. You need to modify the data 
accordingly in order to determine the definite curve values.
To use the Multiple IGV Curves feature, you need a 
manufacturers performance map of curves at different IGV 
operating conditions.
Refer to Entering Curve 
Data section for more 
information.9-26
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Rotating Operations 9-27
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ThThe following is a brief description of the fields and buttons 
found within the IGV Curve Collections group. 
 Figure 9.11
Fields Description
IGV Curve 
Collections list
Displays the list of curve collection available in the unit 
operation. Each curve collection contains a set of data 
curves at a particular inlet guide vane.
Curve Collection 
name
Allows you to rename the selected curve collection in 
the list.
Curve IGV Allows you to specify the inlet guide vane position that 
the entered curve set data is at (or for).
Current IGV Allows you to specify the current position that the 
compressor is operating at. You can specify this value 
to different values during operation or specify this 
value in controllers during Dynamics mode.
Buttons Description
Add Curve 
Collection
Adds another empty curve collection to the IGV Curve 
Collections list.
The Plot All Collections checkbox is useful if you want to see all 
the curves for all the curve collection (in the compressor) appear in 
one plot. This feature is particularly useful if all the curves data is 
based on one speed.9-27
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9-28 Centrifugal Compressor or 
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ThCreating Multiple Curve Collections
The following are methods on how you can create multiple curve 
collections:
1. Enter the data for the curve(s). All of these values will be 
stored under a curve collection named CurveCollection-1.
2. Click the Set Simple Curves button.
3. Two hypothetical curve collections will appear (named 
CurveCollection-2 and CurveCollection-3). These two 
new collections will provide you with rough data for curves 
generated with lighter or heavier components. These 
estimated values are based on the values entered for 
CurveCollection-1.
OR
1. Enter the data for the curve(s). All of these values will be 
stored under a curve collection.
2. Click the Add Curve Collection button.
3. Repeat step #1 to enter the data for the new curve 
collection.
4. Repeat steps #2 to #3 for each additional curve collection.
Del. Curve 
Collection
Deletes the selected curve collection in the IGV Curve 
Collections list.
Set Simple 
Curves
Creates two more curve collections with curve data based 
on the curve collection in the IGV Curve Collections list.
The data values within the two new curve collections are 
estimated values for testing purposes only. You should 
modify this data accordingly to specify your actual curve 
values.
The values given in CurveCollection-2 and CurveCollection-3 
are for testing purposes only. You need to modify the data 
accordingly in order to determine the definite curve values.
Buttons Description
Refer to Entering Curve 
Data section for more 
information.
Refer to Entering Curve 
Data section for more 
information.9-28
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Rotating Operations 9-29
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ThFlow Limits Page
There is a certain range that the dynamic Centrifugal 
Compressors or Expanders can operate in depending on its 
operating speed. The lower flow limit of a Centrifugal 
Compressor is called the surge limit, whereas the upper flow 
limit is called the stonewall limit. In HYSYS, you can specify the 
flow limits of a Centrifugal Compressor or Expander by plotting 
surge and stonewall curves. 
From the Flow Limits page, it is possible to add Surge or 
Stonewall curves for the Centrifugal Compressor. 
When a dynamic Centrifugal Compressor reaches its stonewall 
limit, HYSYS fixes the flow at that Centrifugal Compressor 
speed. When a Centrifugal Compressor reaches the surge limit, 
the flow reverses and cycles continuously causing damage to 
 Figure 9.12
If you are working exclusively in Steady State mode, you are 
not required to change any information on the Flow Limits 
page.
The procedure for adding or editing a Stonewall curve is 
similar to the procedure for adding or editing a Surge curve.9-29
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9-30 Centrifugal Compressor or 
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Ththe Centrifugal Compressor. This phenomenon is modeled in 
HYSYS by causing the flow rate through the Centrifugal 
Compressor to fluctuate randomly below the surge flow.
Adding or Editing a Surge Curve
To add or edit a Surge curve, follow this procedure:
1. Click the Surge Curve button. The Surge flow curve 
property view appears.
2. From the Speed Units drop-down list, select the units you 
want to use for the speed measurements.
3. From the Flow Units drop-down list, select the units you 
want to use for the flow measurements.
4. Specify the speed and flow data points for the curve.
5. Once you have entered all the data points, click the Close 
icon  to return to the Compressor or Expander property 
view.
6. Select the Use Surge Curve checkbox to use the surge 
curve for the compressor or expander calculations.
 Figure 9.139-30
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ThDeleting data of a Surge Curve
To delete data within a surge curve, do the following:
1. Click the Surge Curve button. The Surge flow curve 
property view appears.
2. Do one of the following:
• To remove a certain data point, select either the speed 
cell or flow cell, and click the Erase Selected button.
• To remove all the data points, click the Erase All button.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
For a Centrifugal Compressor or Expander unit operation it is 
strongly recommended that the elevation of the inlet and exit 
nozzles are equal. If you want to model static head, the entire 
piece of equipment can be moved by modifying the Base 
Elevation relative to Ground Elevation field.
Inertia Page
The inertia modeling parameters and the friction loss associated 
with the impeller in the Centrifugal Compressor can be specified 
on the Inertia page. 
If you are working exclusively in Steady State mode, you are 
not required to change any information on the Nozzles page.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the Inertia page.
The HYSYS Dynamics license is required to use the Inertia 
features found on this page. 
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.
Refer to Section 1.6.4 
- Inertia in the HYSYS 
Dynamic Modeling 
guide for more 
information.9-31
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9-32 Centrifugal Compressor or 
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ThElectric Motor Page
The Electric Motor page allows you to drive your rotating unit 
operation through the designation of a motor torque versus 
speed curve. These torque vs. speed curves can either be 
obtained from the manufacturer for the electric motor being 
used or from a typical curve for the motor type. 
For most process industry applications, a NEMA type A or B 
electric motor is used. When you use the Electric Motor option 
the torque (and power) generated by the motor is balanced 
against the torque consumed by the rotating equipment.
When you activate the Electric Motor option:
• An On checkbox will appear at the bottom of the 
Compressor property view, which can be used to turn the 
motor on and off.
• The Compressor operation icon in the PFD changes to 
include a motor.
The Electric Motor functionality is only relevant in Dynamics 
mode.
The Electric Motor option uses one degree of freedom in your 
dynamic specifications.
The results of the Electric Motor option are presented on the 
Power Page in the Performance Tab of the rotating 
equipment operation.
 Figure 9.149-32
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Rotating Operations 9-33
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ThThe following table lists and describes the objects in the Electric 
Motor page:
Object Description
Synchronous Speed 
cell
Allows you to specify the synchronous speed of the 
motor.
Full Load Speed cell Allows you to specify the design speed of the 
motor.
Full Load Torque cell Allows you to specify the design torque of the 
motor.
Full Load Power cell Allows you to specify the design power of the 
motor.
Gear Ratio cell Allows you to manipulate the gear ratio. The gear 
ratio is the rotating equipment’s speed divided by 
the motor speed.
Motor Inertia cell Allows you to specify the motor inertia.
Motor Friction Factor 
cell
Allows you to specify the motor friction factor.
User Electric Motor 
checkbox
Allows you to toggle between using or ignoring the 
electric motor functionality.
Speed vs Torque 
Curve button
Allows you to view the plot and specify the data in 
the Speed vs. Torque Curve Property View.
Size Inertia button Allows you to calculate the inertia based on the 
following equation3:
where:
I = inertia ( )
P = full load power of the motor (kW)
N = full load speed of the motor (rpm/1000)
Simple radio button Allows you to select the Simple model for the 
modelling option.
Breakdown radio 
button
Allows you to select the Breakdown model for the 
modelling option.
Electric Brake 
checkbox
Allows you to model the torque force on the 
rotating equipment simply by changing the sign of 
the produced torque value.
Gearing checkbox Allows the gear ratio to be updated during 
integration.
A zero value for the gear ratio indicates a 
decoupling of the equipment.
I 0.0043 P
N
---⎝ ⎠
⎛ ⎞ 1.48
=
kg m3⋅
Refer to Operation 
Model section for more 
information.9-33
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9-34 Centrifugal Compressor or 
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ThTheory
The definition of torque is found from the following equation:
where:  
P = power consumption (kW)
T = torque (Nm)
= synchronous speed (rpm)
The synchronous electric motor speed can be found from:
where:  
f = power supply frequency (Hz), typically either of 50 or 60
p = number of poles on the stator 
The number of poles is always an even number of 2, 4, 6, 8, 10, 
and so forth. In North America, common motor speeds are 
always 3600, 1800, 1200, 900, 720, and so forth.
The relationships of inertia and friction loss in the total energy 
balance are the same as for the pump and compressor 
operations.
Operation Model
There are three ways to use the Electric Motor curve, each with 
progressing rigor.
• Simple Model. The easiest calculation is the Simple 
modelling option (default). This model is useful if you 
just want to model the startup/shutdown transient and 
want to keep the equipment at the fixed full load speed 
once operating. In this mode, once the speed has 
accelerated enough to become larger than the last 
(9.11)
(9.12)
P T ω 2 π×××
1000 60×
--------------------------------=
ω
ω 120f
p
----------=9-34
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Rotating Operations 9-35
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Th(largest) curve speed value entered, the motor speed 
immediately is set to the full load speed and remains 
there until the motor is turned off. If the process invokes 
a larger torque than the motor curve suggests the motor 
can produce, the speed still remains synchronous and 
remains at its full load value.
• Breakdown Model. The Breakdown modelling option 
allows the speed to reduce if the system torque or 
resistance gets too large. To use this option, the largest 
(last) curve speed value entered should be just less than 
the full load speed value. This provides for a smooth 
transition in operation. You can drop the curve to a lower 
torque than the breakdown torque if desired.
• Simple Model Modified. The third modelling approach is 
to use the Simple model option, but enter the speed vs 
torque curve up to a speed value of 99.99% of the 
synchronous speed. In this case the full load speed 
entered is only used, if necessary, to calculate the full 
load torque and is not used otherwise. With this 
approach, the speed vs torque curve must ascend or 
drop from the breakdown torque to approach zero torque 
at 100% speed. For most motor types, this approach is 
nearly vertical (asymptotic). This modelling approach 
allows for the simulation of the slippage of the motor 
speed based upon the actual and current system 
resistance. The operating speed of the motor will then 
move based upon the process model operation. Use a 
near vertical curve to keep a constant speed or level it off 
more to allow greater slip. This performance should be 
predicted by using an accurate manufacturers torque vs 
speed curve.
The speed and torque are not solved simultaneously with the 
pressure flow solution but instead is lagged by a time step. 
You may need to use a smaller time step to ensure accuracy 
and pressure flow solver convergence.9-35
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9-36 Centrifugal Compressor or 
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ThSpeed vs. Torque Curve Property View
The Speed vs. Torque Curve property view displays the data 
curve of speed versus torque in both table and plot format. 
To access the Speed vs. Torque Curve property view, click the 
Speed vs Torque Curve button on the Electric Motor page of 
the Rating tab. 
The following table lists and describes the objects available in 
the Speed vs. Torque Curve property view:
 Figure 9.15
The values under the Speed and Torque columns are entered 
as a percent of the Full Load values.
The Speed vs. Torque curve must always contain a 0% speed 
value.
The maximum table speed cannot be greater than the value 
in the Maximum X value field. The Maximum X value is the 
ratio of the full load speed to the synchronous speed.
During integration, the current operating point appears on 
the Torque vs. Speed curve.
Object Description
Maximum X value 
display field
Displays the ratio of the full load speed to the 
synchronous speed.
Speed column Allows you to specify speed percentage values you 
want to plot.9-36
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Rotating Operations 9-37
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Th9.1.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the Centrifugal Compressor or Expander.
9.1.6 Performance Tab
The Performance page contains the calculated results of the 
compressor or expander.
Results Page
On the Results page, you can view a table of calculated values 
for the Centrifugal Compressor or Expander:
Torque column Allows you to specify the torque percentage values 
associated with the speed.
Erase Selected 
button
Allows you to delete the row containing both speed 
and torque percentage values of the selected cell.
Erase All button Allows you to delete all the values in the table.
The PF Specs page is relevant to dynamics cases only.
• Adiabatic Head
• Polytropic Head
• Adiabatic Fluid Head
• Polytropic Fluid Head
• Adiabatic Efficiency
• Polytropic Efficiency
• Power Produced
• Power Consumed
• Friction Loss
• Rotational inertia
• Fluid Power
• Polytropic Head Factor
• Polytropic Exponent
• Isentropic Exponent
• Speed
Object Description
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.9-37
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9-38 Centrifugal Compressor or 
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ThPower Page
The Power page is only available for the compressor. The 
information displayed in this page is:
• Compressor rotor power
• Compressor rotor torque
• Electric motor power
• Electric motor torque
• Electric motor speed
9.1.7 Dynamics Tab
The Dynamics tab contains the following pages:
• Specs
• Holdup
• Stripchart
Specs Page
The dynamic specifications of the Centrifugal Compressor or 
Expander can be specified on the Specs page.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through this tab.
 Figure 9.169-38
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Rotating Operations 9-39
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ThIn general, two specifications are required in the Dynamics 
Specifications group. You should be aware of specifications 
which may cause complications or singularity in the pressure 
flow matrix. Some examples of such cases are:
• The Pressure Increase checkbox should not be 
selected if the inlet and exit stream pressures are 
specified.
• The Speed checkbox should not be selected if the Use 
Characteristic Curves checkbox is not selected.
The possible dynamic specifications are as follows:
Duty
The duty is defined, in the case of the Centrifugal Compressor 
operation, as the power required to rotate the shaft and provide 
energy to the fluid. The duty has three components: 
The duty in a Centrifugal Compressor should be specified only if 
there is a fixed power available to be used to drive the shaft.
Efficiency (Adiabatic and Polytropic)
For a dynamic Centrifugal Compressor, the efficiency is given as 
the ratio of the isentropic power required for compression to the 
actual energy imparted to the fluid. The efficiency, , is defined 
as:
where:  
W = isentropic power
F1 = molar flow rate of the inlet gas stream
Duty = Power imparted to the fluid + Power required to 
change the rotational speed of the shaft + Power lost 
due to mechanical friction loss
(9.13)
(9.14)
η
η W to system( )
F1 MW( ) h2 h1–( )
-----------------------------------------=9-39
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9-40 Centrifugal Compressor or 
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ThMW = molecular weight of the gas
h1 = inlet head
h2 = outlet head
For a dynamic Expander, the efficiency, , is defined as:
If a polytropic efficiency definition is required, the polytropic 
work should be provided in Equation (9.14) or Equation 
(9.15). If an adiabatic efficiency definition is required, the 
isentropic work should be provided.
The general definition of the efficiency does not include the 
losses due to the rotational acceleration of the shaft and seal 
losses. Therefore, the efficiency equations in dynamics are not 
different from the general efficiency equations defined in 
Section 9.1.1 - Theory. This is true since the actual work 
required by a steady state Centrifugal Compressor is the same 
as the energy imparted to the fluid.
If the Centrifugal Compressor or Expander curves are specified 
in the Curves page of the Rating tab, the adiabatic or polytropic 
efficiency can be interpolated from the flow of gas and the speed 
of the Centrifugal Compressor or Expander.
Pressure Increase
A Pressure Increase specification can be selected if the pressure 
drop across the Centrifugal Compressor is constant.
(9.15)
η
η
F1 MW( ) h1 h2–( )
W from system( )
-----------------------------------------=9-40
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Rotating Operations 9-41
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ThHead
The isentropic or polytropic head, h, can be defined as a 
function of the isentropic or polytropic work. The relationship is:
where:  
W = isentropic or polytropic power
MW = molecular weight of the gas
CF =  correction factor (For a compressor, this factor is the 
inverse value of the adiabatic/polytropic efficiency; for 
an expander, it is the adiabatic/polytropic efficiency.)
F1 = molar flow rate of the inlet gas stream
g = gravity acceleration
If the Centrifugal Compressor or Expander curves are provided 
in the Curves page of the Rating tab, the isentropic or polytropic 
head can be interpolated from the flow of gas and the speed of 
the Centrifugal Compressor or Expander.
Fluid Head
The Fluid Head is the produced head in units of energy per unit 
mass.
Capacity
The capacity is defined as the actual volumetric flow rate 
entering the Centrifugal Compressor or Expander. A capacity 
specification can be selected if the volumetric flow to the unit 
operation is constant.
(9.16)W MW( )F1 CF( )gh=9-41
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9-42 Centrifugal Compressor or 
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ThSpeed
The rotational speed of the shaft, , driving the Centrifugal 
Compressor or being driven by the Expander can be specified. 
Shift to Reciprocating Compressor (Positive 
Displacement)
Select the Reciprocating (Positive Displacement) checkbox 
if you want to change the Centrifugal Compressor to a 
Reciprocating Compressor. You can change the Centrifugal 
Compressor to a Reciprocating Compressor at any time. The 
reciprocating checkbox option is only available with the 
compressor unit operation. 
Use Characteristic Curves
Select the Use Characteristic Curves checkbox, if you want to 
use the curve(s) specified in the Curves page of the Rating tab. 
If a single curve is specified in a dynamics Centrifugal 
Compressor, the speed of the Centrifugal Compressor is not 
automatically set to the speed of the curve (unlike the steady 
state Centrifugal Compressor or Expander unit operation). A 
different speed can be specified and HYSYS extrapolates values 
for head and efficiency.
Linker Power Loss
To specify the power loss (negative for a power gain) of the 
linked operations, select the Linker Power Loss checkbox.
Electric Motor
Select the Electric Motor checkbox if you want to use the 
electric motor functionality.
ω
Refer to Section 9.2 - 
Reciprocating 
Compressor for more 
information.9-42
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Rotating Operations 9-43
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ThSurge Controller
The Create Surge Controller button on the Specs page of the 
Dynamics tab opens a Surge Controller property view (which is 
owned by the Centrifugal Compressor). If you decide to delete 
the Centrifugal Compressor, the surge controller associated with 
the Centrifugal Compressor is deleted as well. The surge 
controller also works exclusively with Centrifugal Compressor 
and Expander unit operations.
As mentioned, a Centrifugal Compressor surges if its capacity 
falls below the surge limit. The surge controller determines a 
minimum volumetric flow rate that the Centrifugal Compressor 
should operate at without surging. This is called the surge flow. 
The surge controller then attempts to control the flow to the 
Centrifugal Compressor at some percent above the surge flow 
(this is typically 10%). The surge controller essentially acts like 
PID Controller operations. The control algorithms used to 
prevent Centrifugal Compressors from surging are extensions of 
the PID algorithm. 
 Figure 9.179-43
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9-44 Centrifugal Compressor or 
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ThTwo major differences distinguish a surge from a regular 
controller:
• The setpoint of the surge controller is calculated and not 
set.
• More aggressive action is taken by the surge controller if 
the Centrifugal Compressor is close to surging.
Connections Tab
The Connections tab is very similar to a PID controller’s 
Connections tab. The inlet volumetric flow to the Centrifugal 
Compressor is automatically defaulted as the process variable 
(PV) to be measured. You must select a Control Valve operation 
as an operating variable (OP), which has a direct effect on the 
inlet flow to the Centrifugal Compressor.
The Upstream Surge Controller Output field contains a list of the 
other surge controllers in the simulation flowsheet. If you select 
an upstream surge controller using the Upstream Surge 
Controller Output field, HYSYS ensures that the output signal of 
the Centrifugal Compressor’s surge controller is not lower than 
an upstream surge controller’s output signal. 
Consider a situation in which two compressors are connected in 
series.
For more information on 
the individual 
parameters which make 
up the Connections tab, 
refer to Chapter 5 - 
Logical Operations
 Figure 9.189-44
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ThAs shown in the previous figure, both surge controllers must use 
the same valve for surge control. If the surge controllers are 
connected in this manner HYSYS autoselects the largest 
controller output. This is done to ensure that surge control is 
adequately provided for both compressors.
Parameters Tab
The parameters tab consists of the following pages:
• Configuration
• Surge Control
Configuration Page
If the process variable (PV) is operating above a certain margin 
over the surge flow limit, the surge controller operates exactly 
as a PID Controller. Therefore, PID control parameters should be 
set on the Configuration page. The process variable range, the 
controller action, operation mode, and the tuning parameters of 
the controller can be set in this page. 
For more information on 
the individual fields in the 
Configuration page, refer 
to Section 5.4.4 - PID 
Controller.9-45
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9-46 Centrifugal Compressor or 
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ThSurge Control Page
Various surge control parameters can be specified on the Surge 
Control page.
A head versus quadratic flow expression relates the surge flow 
to the head of the Centrifugal Compressor. 
where:  
Fs = surge flow (m3/s)
hm = head of the Centrifugal Compressor
A, B, C, D = parameters used to characterize the relationship 
between surge flow and head
You can enter surge flow parameters A, B, C, and D in order to 
characterize the relationship between the surge flow and head.
 Figure 9.19
(9.17)hm A B Fs( ) C Fs( )2 D Fs( )3+ + +=9-46
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ThThe next three parameters in the Surge Control Parameters 
section are defined as follows:
Monitor Tab
The Monitor tab displays a chart that graphs the three variables 
(PV, SP, and OP) of the surge controller
User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for the current operation. 
Holdup Page
Typical Centrifugal Compressors and Expanders in actual plants 
usually have significantly less holdup than most other unit 
operations in a plant. Therefore, the volume of the Centrifugal 
Compressor or Expander operation in HYSYS cannot be specified 
and is assumed to be zero on the Holdup page.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
Surge Control 
Parameter
Description
Control Line (%) The primary setpoint for the surge controller. This line 
is defaulted at 10% above the surge flow. If the flow is 
above the backup line then the surge controller acts as 
a normal PID controller.
Backup Line (%) Set somewhere between the control line and the surge 
flow. This line is defaulted at 5% above the surge flow. 
If the flow to the Centrifugal Compressor falls below 
the backup line, more aggressive action is taken by the 
controller to prevent a surge condition.
Quick Opening 
(%/sec)
Aggressive action is taken by increasing the desired 
actuator opening at a rate specified in this field until 
the volumetric flow to the Centrifugal Compressor rises 
above the backup line.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 
- Stripchart Page/Tab 
for more information.9-47
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9-48 Reciprocating Compressor
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Th9.2 Reciprocating 
Compressor
In Section 9.1 - Centrifugal Compressor or Expander a 
Centrifugal Compressor type is presented. The following section 
discusses a Reciprocating Compressor. A Reciprocating 
Compressor is just another type of compressor used for 
applications where higher discharge pressures and lower flows 
are needed. It is known as a positive displacement type. 
Reciprocating Compressors have a constant volume and variable 
head characteristics, as compared to the Centrifugal 
Compressor that has a constant head and variable volume.
In HYSYS, Centrifugal and Reciprocating Compressors are 
accessed via the same compressor unit operation. However, the 
solution methods differ slightly as a Reciprocating Compressor 
does not require a compressor curve and the required geometry 
data. The present capability of Reciprocating Compressors in 
HYSYS is focused on a single stage compressor with a single or 
double acting piston. A typical solution method for a 
Reciprocating Compressor is as follows:
• Always start with a fully defined inlet stream, in other 
words, inlet pressure, temperature, flow rate, and 
compositional data are known.
• Specify compressor geometry data, for example, number 
of cylinders, cylinder type, bore, stroke, and piston rod 
diameter. HYSYS provides default values too.
• Compressor performance data, in other words, adiabatic 
efficiency or polytropic efficiency, and constant 
volumetric efficiency loss are specified.
• HYSYS calculates the duty required, outlet temperature if 
the outlet pressure is specified.
For Reciprocating Compressors there is no direct 
relationship between the head and flow capacity.9-48
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ThSome of the features in the dynamic Reciprocating Compressor 
unit operation include:
• Dynamic modeling of friction loss and inertia.
• Dynamic modeling which supports shutdown and startup 
behaviour.
• Dynamic modeling of the cylinder loading.
• Linking capabilities with other rotational equipment 
operating at the same speed with one total power.
9.2.1 Theory
In a single stage Reciprocating Compressor, it comprises of the 
basic components like the piston, the cylinder, head, connecting 
rod, crankshaft, intake valve, and exhaust valve. This is 
illustrated in Figure 9.20. HYSYS is capable of modeling a 
multi-cylinder in one Reciprocating Compressor with a single 
acting or double acting piston. 
A single acting compressor has a piston that is compressing the 
gas contained in the cylinder using one end of the piston only. A 
double acting compressor has a piston that is compressing the 
gas contained in the cylinder using both ends of the piston. The 
piston end that is close to the crank is called crank end, while 
the other is named as outer.
The thermodynamic calculations for a Reciprocating Compressor 
are the same as a Centrifugal Compressor. Basically, there are 
two types of compression being considered:
 Figure 9.209-49
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9-50 Reciprocating Compressor
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Th• Isentropic/adiabatic reversible path. A process 
during which there is no heat added to or removed from 
the system, and the entropy remains constant. 
PVk=constant, where k is the ratio of the specific heat 
(Cp/Cv).
• Polytropic reversible path. A process in which changes 
in the gas characteristic during compression are 
considered.
Details of the equation are found in Section 9.1.1 - Theory. 
Reference1 has the information about the operation of the 
Reciprocating Compressor.
The performance of the Reciprocating Compressor is evaluated 
based on the volumetric efficiency, cylinder clearance, brake 
power, and duty.
Cylinder clearance, C, is given as: 
where:  
PD = positive displacement volume
The sum of all clearance volume for all cylinders includes both 
fixed and variable volume. C is normally expressed in a 
fractional or percentage form. 
The piston displacement, PD, is equal to the net piston area 
multiplied by the length of piston sweep in a given period of 
time. This displacement can be expressed as follows:
• For a single-acting piston compressing on the outer end 
only:
(9.18)
(9.19)
C Sum of all clearance volume for all cylinders
PD
-----------------------------------------------------------------------------------------------------------=
PD π D2 stroke⋅ ⋅
4
---------------------------------=9-50
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Th• For a single-acting piston compressing on the crank end 
only:
• For double-acting piston (other than tail rod type):
• For a double-acting piston (tail rod type):
where:  
d = piston rod diameter
D = piston diameter
PD includes the contributions from all cylinders and both ends of 
any double acting. If a cylinder is unloaded then its contribution 
does not factor in.
The volumetric efficiency is one of the important parameters 
used to evaluate the Reciprocating Compressor's performance. 
Volumetric efficiency, VE, is defined as the actual pumping 
capacity of a cylinder compared to the piston displacement 
volume. 
VE is given by:
(9.20)
(9.21)
(9.22)
(9.23)
PD π D2 d2–( ) stroke⋅ ⋅
4
-------------------------------------------------=
PD π 2D2 d2–( ) stroke⋅ ⋅
4
----------------------------------------------------=
PD π 2D2 2d2–( ) stroke⋅ ⋅
4
--------------------------------------------------------=
VE 1 L–( ) C
Zs
Zd
-----
Pd
Ps
-----⎝ ⎠
⎛ ⎞
1
k
--
1––=9-51
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9-52 Reciprocating Compressor
ww
Thwhere:  
Pd = discharge pressure
Ps = suction pressure
L = effects of variable such as internal leakage, gas friction, 
pressure drop through valves, and inlet gas preheating
k = heat capacity ratio, Cp/Cv
Zd = discharge compressibility factor
Zs = suction compressibility factor
C = clearance volume
To account for losses at the suction and discharge valve, an 
arbitrary value about 4% VE loss is acceptable. For a non-
lubricated compressor, an additional 5% loss is required to 
account for slippage of gas. If the compressor is in propane, or 
similar heavy gas service, an additional 4% should be 
subtracted from the volumetric efficiency. These deductions for 
non-lubricated and propane performance are both approximate, 
and if both apply, cumulative. Thus, the value of L varies from 
(0.04 to 0.15 or more) in general.9-52
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Rotating Operations 9-53
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ThRod Loading
Rod loads are established to limit the static and inertial loads on 
the crankshaft, connecting rod, frame, piston rod, bolting, and 
projected bearing surfaces.
It can be calculated as follows:
Maximum Pressure
The maximum pressure that the Reciprocating Compressor can 
achieve is:
Where the maximum discharge pressure ratio, PRmax, is 
calculated from:
 Figure 9.21
Load in compression, Lc
(9.24)
Load in tension, Lt
(9.25)
(9.26)
(9.27)
Lc PdAp Ps Ap Ar–( )–=
Lt Pd Ap Ar–( ) PsAp–=
Pmax Ps PRmax⋅=
PRmax
Zd
Zs C⋅
------------- 1 L– VE– C+( )
k
=
9-53
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9-54 Reciprocating Compressor
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ThFlow
Flow into the Reciprocating Compressor is governed by the 
speed of the compressor. If the speed of the compressor is 
larger than zero then the flow rate is zero or larger then zero 
(but never negative). The molar flow is then equal to:
where:  
N = speed, rpm
 = gas density
MW = gas molecular weight
If the speed of the compressor is exactly zero, then the flow 
through the unit is governed by a typical pressure flow 
relationship, and you can specify the resistance in zero speed 
flow resistance, kzero speed. 
The flow equation is as follows:
where:  
 = frictional pressure drop across the compressor
(9.28)
(9.29)
F 1 L
100
--------–⎝ ⎠
⎛ ⎞ C
Zs
Zd
-----
Pd
Ps
-----⎝ ⎠
⎛ ⎞
1
k
--
1––
N
60
----- PD ρ⋅⋅
MW
--------------------------=
ρ
 F kzero speed ρ ΔPfriction⋅⋅=
ΔPfriction9-54
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Th9.2.2 Reciprocating 
Compressor Property View
There are two ways that you can add a Compressor to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Rotating Equipment radio button.
3. From the list of available unit operations, select 
Compressor.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Compressor icon. 
The Compressor property view appears.
 Figure 9.22
Compressor icon9-55
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9-56 Reciprocating Compressor
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ThDo one of the following to complete the Reciprocating 
Compressor installation:
• On the Design tab, click the Parameters page. Select 
the Reciprocating radio button in the Operating Mode 
group.
• On the Dynamics tab, click on the Specs page. Select 
the Reciprocating (Positive Displacement) checkbox 
in the Dynamic Specifications group.
9.2.3 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Links
• Settings
• User Variables
• Notes
Connections Page
The Connections page allows you to specify the inlet stream, 
outlet stream, and energy stream.  
 Figure 9.23
The Connections page is identical to the Connections page 
for the Centrifugal Compressor property view. 
Refer to the section on 
the Centrifugal 
Compressor or Expanders 
Connections Page for 
more information.9-56
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ThParameters Page
The Parameters pages is identical to the Centrifugal Compressor 
as shown in the figure below.   
You can specify the duty of the attached energy stream on this 
page, or allow HYSYS to calculate it. The adiabatic and 
polytropic efficiencies appear as well.
 Figure 9.24
The difference between the Centrifugal and Reciprocating 
compressor is the missing Curve Input Option group.
You can switch between Centrifugal and Reciprocating 
Compressor by selecting one of the radio buttons in the 
Operating Mode group.
You can specify only one efficiency, either adiabatic or 
polytropic. If you specify one efficiency and a solution is 
obtained, HYSYS back calculates the other efficiency, using 
the calculated duty and stream conditions. 
The Reciprocating Compressor has a higher adiabatic 
efficiency than the Centrifugal Compressor, normally in the 
range of 85% - 95%.
Maximum pressure ratio can be achieved at zero volume 
efficiency.9-57
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9-58 Reciprocating Compressor
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ThLinks Page
The Links page is identical to the Centrifugal Compressor as 
shown in the figure below.
Settings Page
The Settings page is used to size the Reciprocating Compressor. 
 Figure 9.25
 Figure 9.26
Refer to Links Page 
section for more 
information.9-58
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Rotating Operations 9-59
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ThA Reciprocating Compressor does not require a characteristic 
curve, however the following compressor geometry information 
is required:
• Number of Cylinders
• Cylinder Type
• Bore
• Stroke
• Piston Rod Diameter
• Constant Volumetric Efficiency Loss
• Default Fixed Clearance Volume
• Zero Speed Flow Resistance (k) - dynamics only
• Typical Design Speed
• Volumetric Efficiency
• Speed
Depending on the cylinder type selected, you have four 
parameters that can be specified. If the cylinder type is of 
double action, you need to specify the fixed clearance volume 
for the crank side and the outer side.
• Fixed Clearance Volume
• Variable Clearance Volume
• Variable Volume Enabled
• Cylinder is Unloaded - dynamics only
The Settings page is only visible when you have activated 
the Reciprocating Compressor option either from the 
Parameters page on the Design tab or the Specs page on the 
Dynamics tab.
Bore is the diameter of the cylinder. 
Stroke is the distance head of piston travels.
Typical Design Speed is the estimated speed for the rotor.
Speed is the actual speed of the rotor.9-59
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9-60 Reciprocating Compressor
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ThIf the Variable Volume Enabled checkbox is selected, you 
need to specify a variable clearance volume. 
If the Cylinder is Unloaded checkbox is selected, the total 
displacement volume is not considered and is essentially zero.
The Size k button allows you to access the Reciprocating 
Pressure-Flow Sizing property view, and specify a pressure drop 
and mass flow rate that is used to calculate the zero speed flow 
resistance of the Reciprocating Compressor.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
The variable clearance volume is used when additional 
clearance volume (external) is intentionally added to reduce 
cylinder capacity.
 Figure 9.27
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.9-60
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Th9.2.4 Rating Tab
The Rating tab contains the following pages:
• Nozzles
• Inertia
• Electric Motor
Nozzles Page
If you are working exclusively in Steady State mode, you are 
not required to change any information on the Nozzles page. 
The Nozzles page in the Reciprocating Compressor is identical to 
the Nozzles page in the Centrifugal Compressor.
Inertia Page
If you are working exclusively in Steady State mode, you are 
not required to change any information on this page. The 
Reciprocating Compressor Inertia page is identical to the one for 
the Centrifugal Compressor.
Electric Motor
If you are working exclusively in Steady State mode, you are 
not required to change any information on this page. The 
Reciprocating Compressor Electric Motor page is identical to the 
one for the Centrifugal Compressor.
Refer to the section on 
the Nozzles Page for 
more information.
Refer to the section on 
the Inertia Page for 
more information.
Refer to the section on 
the Electric Motor Page 
for more information.9-61
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9-62 Reciprocating Compressor
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Th9.2.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
9.2.6 Performance Tab
The Performance tab consists of the Results page.
Results Page
On the Results page, you can view a table of calculated values 
for the Compressor.
In the Results group you will find the following fields:
• Adiabatic Head
• Polytropic Head
• Adiabatic Efficiency
• Polytropic Efficiency
• Power Consumed
• Friction Loss
• Rational Inertia
• Fluid Power
• Polytropic Head Factor
• Polytropic Exponent
• Isentropic Exponent
• Speed
In the Reciprocating group you will find the following fields:
• Total Effective Piston Displacement Volume
• Total Effective Fractional Clearance Volume
• Maximum Pressure Ratio
• Load in Compression
• Load in Tension
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.9-62
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Th9.2.7 Dynamics Tab
The Dynamics tab is identical to the one for the Centrifugal 
Compressor. However, when using a Reciprocating Compressor 
you cannot use the Characteristic Curves specification or create 
a Surge Controller.
9.3 Pump
The Pump operation is used to increase the pressure of an inlet 
liquid stream. Depending on the information specified, the Pump 
calculates either an unknown pressure, temperature or pump 
efficiency.
The dynamics Pump operation is similar to the Compressor 
operation in that it increases the pressure of its inlet stream. 
The Pump operation assumes that the inlet fluid is 
incompressible.
Some of the features in the dynamic Pump include:
• Dynamic modeling of friction loss and inertia.
• Dynamic modeling which supports shutdown and startup 
behaviour.
• Multiple head and efficiency curves.
• Modeling of cavitation if Net Positive Suction Head 
(NPSH) is less than a calculated NPSH limit.
• Linking capabilities with other rotational equipment 
operating at the same speed with one total power.
If you are working exclusively in Steady State mode, you are 
not required to change any information on the pages 
accessible through the Dynamics tab.
Refer to Section 9.1.7 - 
Dynamics Tab for more 
information.9-63
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9-64 Pump
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Th9.3.1 Theory
HYSYS uses the following assumptions and equations in 
calculating the unknown Pump unit operation variables.
• Calculating the ideal power of the pump required to raise 
the pressure of the liquid: 
The calculations are based on the standard pump 
equation for power, which uses the pressure rise, the 
liquid flow rate, and density:
where:  
Pout = pump outlet pressure
Pin = pump inlet pressure
• Calculating the actual power of the pump:
The actual power requirement of the Pump is defined in 
terms of the Pump Efficiency:
When the efficiency is less than 100%, the excess energy 
goes into raising the temperature of the outlet stream.
Combining the above equations leads to the following 
expression for the actual power requirement of the Pump:
The actual power is also equal to the difference in heat flow 
between the outlet and inlet streams:
(9.30)
(9.31)
(9.32)
Power Requiredactual = (Heat Flowoutlet - Heat 
Flowinlet)
(9.33)
Power Requiredideal
Pout Pin–( ) Flow Rate×
Liquid Density
--------------------------------------------------------------=
Efficiency %( )
Power Requiredideal
Power Requiredactual
-------------------------------------------------------- 100%×=
Power Requiredactual
Pout Pin–( ) Flow Rate 100%××
Liquid Density Efficiency %( )×
-----------------------------------------------------------------------------------=9-64
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ThThe pump calculations that HYSYS performs assume that the 
liquid is incompressible. The density is constant, and the liquid 
volume is independent of pressure.
This is the usual assumption for liquids well removed from the 
critical point, and the standard pump equation given above is 
generally accepted for calculating the power requirement. 
However, if you want to perform a more rigorous calculation for 
pumping a compressible liquid (for example, one near the 
critical point), you should install a compressor to represent the 
pump.
If you choose to represent a Pump by installing a Compressor in 
HYSYS, the power requirement and temperature rise of the 
Compressor is always greater than those of the Pump (for the 
same fluid stream), because the compressor treats the liquid as 
a compressible fluid. When the pressure of a compressible fluid 
increases, the temperature also increases, and the specific 
volume decreases. More work is required to move the fluid than 
if it were incompressible, exhibiting little temperature rise, as is 
the case with a HYSYS Pump.
The ideal power required, W, to increase the pressure of an 
incompressible fluid is:
where:  
P1 = pressure of the inlet stream
P2 = pressure of the exit stream
 = density of the inlet stream
F = molar flow rate of the stream
MW = molecular weight of the fluid
(9.34)
For a pump, an efficiency of 100% does not correspond to a 
true isentropic compression of the liquid.
W
P2 P1–( )F MW( )
ρ
------------------------------------------=
ρ
9-65
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9-66 Pump
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Th9.3.2 Pump Property View
There are two ways that you can add a Pump to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Rotating Equipment radio button.
3. From the list of available unit operations, select Pump.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Pump icon. 
The Pump property view appears.
The On checkbox enables you activate or deactivate the pump. 
This checkbox has different meanings, depending on whether 
you are in steady state or dynamic operations.
 Figure 9.28
Pump icon9-66
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ThIn Steady State mode:
• Selected On checkbox indicates the Pump is on and 
works as normal. (Default setting)
• Cleared On checkbox indicates the Pump is off and the 
inlet stream passes through the pump operation 
unchanged. In other words, the outlet stream is exactly 
the same as the inlet stream.
In Dynamics mode:
• Selected On checkbox indicates the Pump is on and 
works as normal. (Default setting)
• Cleared On checkbox will set the Electric Motor torque 
and power to 0.0.
In Steady State mode, the On checkbox is always available. In 
Dynamic mode, the On checkbox is only available for the 
following situations:
• Pump speed is being used as a dynamic spec. (This 
requires that curves are used as a dynamic spec.)
• Power is being used as a dynamic spec.
• Electric motor is being used.
If the pump speed and power are not specified and the electric 
motor is not being used, the On checkbox will be grayed out.
When you use the On option in either Steady State or Dynamic 
modes, you should specify a pressure rise rather than specify 
the pressures of the inlet stream and outlet stream.
If you specify a Delta P, this value is simply ignored when 
you turn the Pump off. 
If you specify the pressures of the inlet stream and outlet 
stream, you get a consistency error when you turn the Pump 
off, as HYSYS attempts to pass the inlet stream conditions to 
the outlet stream.9-67
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9-68 Pump
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Th9.3.3 Design Tab
The Design tab consists of the following pages:
• Connections
• Parameters
• Curves
• Links
• User Variables
• Notes
Connections Page
On the Connections page, you can specify the pump name, fluid 
package, and inlet, outlet, and energy streams of the Pump.
Parameters Page
The Parameters page enables you to specify the adiabatic 
efficiency, Delta P, and pump energy (power) parameters. 
However, if the inlet stream is fully defined, only two of the 
following variables need to be specified for the Pump to 
calculate all unknowns:
• Outlet Pressure or Pressure Drop (pressure difference 
between inlet and outlet stream)
• Efficiency (pump efficiency)
• Pump Energy or Duty (actual power)
 Figure 9.299-68
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ThHYSYS can also back-calculate the inlet pressure. 
Curves Page
The Curves page allows you to configure the pump based on the 
pump curve. On the Curves page, you can create the pump 
curve using the equation provided by the pump manufacturer.
 Figure 9.30
 Figure 9.319-69
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ThTo generate a pump curve:
1. On the Curves page, select the units for the Head, Flow 
Basis, and Flow Rate variables.
2. Enter the coefficients for the quadratic pump equation. The 
coefficient values come from the pump manufacture.
3. Select the Activate Curves checkbox.
Based on the calculated pump curve results, HYSYS 
determines the pressure rise across the Pump for the given 
flowrate. 
Phasing out one method
Currently HYSYS Pump operation provides two methods to 
generate pump curve data in Steady State: curve equation and 
curve characteristics.
• The curve equation function was originally provided in 
older versions of HYSYS (before 2004 release). The 
function was limited to a pump curve data generated by 
the curve equation, which may not accurately reflect the 
actual pump operating behavior.
• The curve characteristics function enables users to 
directly describe the pump operating behavior in terms of 
Flow, Head, Efficiency, and speed issues. By entering 
these variable values, a more accurate pump curve data 
is achieved. For the details of the curve characteristics 
concept, please refer to the Compressor section.
The Activate Curves checkbox can only be selected if the Use 
Curves checkbox in the Curves page of the Rating tab is 
clear.
To avoid a consistency error, ensure that you have not 
specified the pressure rise across the Pump, either in the 
attached streams or in the operation itself.9-70
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Rotating Operations 9-71
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ThIf an old case is loaded into HYSYS and the old case contained 
converged pumps that use curve equation to generate the pump 
curves, HYSYS automatically populates a curve characteristic set 
to generate a new pump curve similar to the old pump curve 
based on the curve equation specifications.
A warning message also appears informing you about the new 
pump curve and suggesting that you switch to the curve 
characteristic method.
To switch to the curve characteristic method:
1. Open the Pump property view.
2. Click on the Design tab and select the Curves page.
3. Clear the Activate Curves checkbox.
4. Click on the Rating tab and select the Curves page.
5. Click the Use Curves checkbox.
6. Click on the Design tab and select the Parameters page.
7. Delete any specified values in the Adiabatic Efficiency field 
or Duty field.
HYSYS does not automatically replace the new pump curve 
with the old pump curve. 
HYSYS supports both methods, however the curve equation 
method will eventually be phased out.9-71
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9-72 Pump
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ThLinks Page
In HYSYS, Pumps can have shafts which are physically 
connected. The rotational equipment linker operates both in 
Steady State and Dynamic mode.
The following table lists and describes the objects in the Links 
page:
 Figure 9.32
Object Description
Previous Link 
field
Displays the HYSYS rotating equipment operation 
connected on one side of the shaft.
Next Link drop-
down list
Allows you to select a rotating equipment operation to 
connect on the other side of the shaft.
Gear Ratio field Displays the ratio of the speed from the next linked 
operation divided by the speed of the current pump.
Total Power Loss 
field
Depending on the configuration of the pump and the 
information specified, you can either:
• View the total power loss of the linked operation.
• Specify the total power loss of the linked 
operation.
Dynamic 
Specification 
checkbox
Allows you to specify the total power loss (or power 
gain by entering a negative value) for the linked 
operation.
You can ignore this option in Steady State mode.
It is not significant which order the Pumps are linked. The 
notion of previous and next links is arbitrary and determined 
by the user.9-72
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Rotating Operations 9-73
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ThLinked Pump operations require curves. In Dynamics mode, to 
fully define a set of linked operations, you must select the Use 
the Characteristic Curves checkbox for each of the linked 
Pumps in the Specs page of the Dynamics tab.
In Dynamics mode when you link rotating operation, the 
pressure flow equations are affected as follow:
• An energy conservation equation is set such that the sum 
of the operation powers equals the total power.
• Each pair of operation has their speeds set to equal.
One additional dynamic specification is usually required for the 
set. The total power loss from the linked operations can be 
specified. For a series of linked Pumps, it is desired to input a 
total power:
An electric motor connected to the current operation or a linked 
operation can also supply the total power.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Total Power Input = - Total Power Loss (9.35)
It is possible to link a Pump to a Compressor and use the 
Pump as a turbine to generate kinetic energy to drive the 
Compressor. If this option is selected, the total power loss is 
typically specified as zero.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.9-73
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9-74 Pump
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Th9.3.4 Rating Tab
If you are working exclusively in Steady State mode, you are 
not required to change any information on most of the pages 
accessible through the Rating tab. The Rating tab consists of the 
following pages:
• Curves
• NPSH
• Nozzles
• Inertia
• Electric Motor
• Startup
Curves Page
The Curves page on the Rating tab allows you to configure the 
pump based on pump curve characteristics generated by the 
pump manufacturer. 
The curve characteristics consist of pump efficiency, pump head, 
pump flow rate, and pump speed variables. The pump can be 
configured based on multiple pump curves and speeds.
The pump curve characteristics method works in both steady 
state and dynamic mode.
 Figure 9.339-74
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Rotating Operations 9-75
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ThThe following table lists and describes the objects in the Curves 
page:
Depending on the type of pump curve you want to generate the 
following information needs to be supplied for the pump to 
solve:
• For a performance curve (one curve), the feed 
temperature and pressure must be supplied along with 
one of flow, duty, outlet pressure or efficiency.
• For normalized curves, the feed temperature and 
pressure must be specified along with two of flow, speed, 
duty, outlet pressure, and efficiency. 
Object Description
Curve Name 
column
Displays the names of the curve data for the pump.
View Curve 
button
Allows you to open the Curve Property View and 
modify the curve characteristic of the selected curve.
This button is only available if there is a curve available 
in the Curve Name column.
Add Curve 
button
Opens the Curve Property View and allows you to 
create a curve.
Delete Curve 
button
Allows you to delete the selected curve in the Curve 
Name column.
This button is only available if there is a curve available 
in the Curve Name column.
Clone Curve 
button
Allows you to duplicate an existing curve.
Plot Curves 
button
Allows you to generate a plot of all the curve in the 
Curves Profiles Property View.
Generate Curves 
button
Allows you to manipulate and generate the curve using 
the Generate Curve Options Property View. This 
option should be used only if the pump curve data is 
not provided by the manufacturer.
Pump Speed field Enables you to specify a pump speed for all the curve 
data.
Use Curves 
checkbox
Enables you to accept the pump curve data generated 
by the curve characteristics.
The Use Curves checkbox can only be selected if the 
Activate Curves checkbox is clear in the Curves page 
of the Design tab.
For the two variables, either flow and/or speed must be 
specified. A pump with duty and efficiency specified can not 
be solved using the curve characteristic option.9-75
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9-76 Pump
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ThIn addition, if outlet pressure or efficiency is supplied as one of 
the variables (for performance or normalized curves) and their 
corresponding curve is a parabola or has multiple flows for a 
given pressure or efficiency, then there may be multiple 
solutions. HYSYS will notify you of this possibility but will still 
solve to the first solution only. If iterations are required, 
basically any problems that do not have both flow and speed 
specified for a normalized problem or no flow for a performance 
problem, then HYSYS deploys the Secant method to converge to 
a solution. The number of maximum iterations is set at 10000 
and is not modifiable.
To specify data for a pump curve:
1. On the Curves page, click the Add Curve button, the Curve 
property view appears. 
2. On the Curve property view, specify the pump speed in the 
Speed field.
3. Specify the flow, head, and %efficiency data points for a 
single curve in the appropriate cells.
4. For each additional curve, repeat step #1 and #2.
• Click the Erase Selected button to delete the entire row 
(Flow, Head or Efficiency) of the selected cell.
• Click the Erase All button to delete all Flow, Head, and 
Efficiency data for the curve.
5.  After entering all your curve data, click the Close icon  to 
return to the Pump property view.
 Figure 9.349-76
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Rotating Operations 9-77
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ThHYSYS uses the curve(s) to determine the appropriate efficiency 
for your operational conditions. If you specify curves, ensure the 
Efficiency values on the Parameters page of the Design tab 
are empty, or a consistency error will be generated.
Curve Property View 
You can access the Curve property view by:
• Clicking the Add Curve button.
• Selecting a curve data and clicking the View Curve 
button.
In the Curve property view, you can specify the following data:
 Figure 9.35
Object Description
 Name field Enables you to designate a name for particular 
curve characteristic data.
Speed field Enables you to specify the rotation speed of the 
pump. This value is only required if you specify 
more than one set of curve characteristic data. 
Each set of curve characteristic data is associated 
to a specific pump rotation speed.
Flow Units field Enables you to select the unit of the flow rate for 
the curve characteristic data.
Head Units field Enables you to select the unit of the head for the 
curve characteristic data.
Flow column Enables you to specify the flow rate data of the 
pump curve. The flow rate values appear along the 
x-axis of the pump curve plot.
Head column Enables you to specify the head data of the pump 
curve. The head values appear along the y-axis of 
the pump curve plot.9-77
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9-78 Pump
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ThIn order to run a stable and realistic dynamic model, HYSYS 
requires you to input reasonable curves. If Compressors or 
Expanders are linked, it is a good idea to ensure that the curves 
plotted for each unit operation span a common speed and 
capacity range. 
Typical curves are plotted in the figure below. 
where:
h = pump head
Efficiency column Enables you to specify the efficiency data of the 
pump curve. The pump efficiency values appear 
along the y-axis of the pump curve plot.
Erase Selected 
button
Enables you to select a cell and erase the data in 
the entire row associated to the selected cell.
Erase All button Enables you to delete all the flow, head, and 
efficiency data of the curve.
The curve characteristics data is normally provided by the 
pump manufacturer. HYSYS can interpolate values for the 
efficiency and head of the Compressor or Expander for 
speeds that are not plotted.
Object Description
 Figure 9.369-78
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Rotating Operations 9-79
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Th= pump efficiency
Capacity = pump flow rate
Curves Profiles Property View
The Curves Profiles property view allows you to see the plot of 
the curve data. 
To access the Curves Profiles property view, click the Plot 
Curves button on the Curves page in the Rating tab of the 
Pump property view.
The following table lists and describes the objects available in 
the Curves Profiles property view:
 Figure 9.37
Object Description
Plot Displays the selected curve data in plot format.
Head radio 
button
Allows you to view the Head vs. Flow curve data plot.
Efficiency radio 
button
Allows you to view the Efficiency vs. Flow curve data 
plot.
Curve Name 
column
Displays the names of the curve data available for the 
plot.
Plot checkboxes Allows you to toggle between displaying and hiding the 
associate curve data in the plot.
Show Operating 
Pt checkbox
Allows you to toggle between displaying and hiding the 
curve data generated by the Pump’s current operating 
conditions and specifications.
η
9-79
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9-80 Pump
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ThGenerate Curve Options Property View
The Generate Curve Options property view allows you to 
generate curve data based on the specified pump design 
parameters. HYSYS automatically generates three curves based 
on three different speeds: user specified speed, user specified 
speed multiplied by low speed %, and user specified speed 
multiplied by low low speed %. 
Each curve is generated using the following data point 
assumptions:
• A point based on the Head of the pump, Capacity of the 
pump, and the assumption that shutoffhead (0 flow rate) 
occurs at 110% of the Design Head value (the 110% 
comes from the Design Head Factor variable).
• A point based on the Head of the pump, Capacity of the 
pump, and the assumption that maximum flow (0 Head) 
occurs at 200% of the design capacity flow rate (the 
200% comes from the Design Flow Factor variable).
• A point based on the following expression:
• A point based on the following expression:
• A point based on the following expression: 
(9.36)
(9.37)
(9.38)
capacity efficiency,( ) 0 design efficiency factor efficiency design×,( )=
capacity efficiency,( ) design flow efficiency design,( )=
capacity efficiency,( ) design flow factor design flow×
efficiency design design efficiency factor×
,(
)
=
9-80
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Rotating Operations 9-81
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ThTo access the Generate Curve Options property view, click the 
Generate Curves button on the Curves page in the Rating tab 
of the Pump property view.
The following table lists and describes the objects available in 
the Generate Curve Options property view:
 Figure 9.38
Object Description
Design Efficiency 
Factor cell
Allows you to manipulate the pump design efficiency 
factor. Default value is 0.90.
Design Efficiency 
cell
Allows you to manipulate the design efficiency of the 
pump. HYSYS provides a default value of 70%.
Design Flow 
Factor cell
Allows you to manipulate the pump design flow factor. 
Default value is 2.
Design Flow cell Allows you to manipulate the pump design flow. 
Default value is 10.
Design Head 
Factor cell
Allows you to manipulate the pump design Head factor. 
Default value is 1.10.
Design Head cell Allows you to specify the design Head of the pump.
Design Speed 
cell
Allows you to specify the design speed of the pump.
Low Speed cell Allows you to manipulate the pump low speed based 
on the percentage value of the pump design speed. 
Default value is 60%.
Low Low Speed 
cell
Allows you to manipulate the pump low low speed 
based on the percentage value of the pump design 
speed. Default value is 30%.
Generate Curves 
button
Allows you to generate the curve data based on the 
specified pump design.
Any previous specified curve data in the Curves page 
of the Rating tab will be deleted, when you generate 
the new curve data.
Cancel button Allows you to exit the Generate Curves Options 
property view without generating any curve data.9-81
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9-82 Pump
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ThNPSH Page
Net Positive Suction Head (NPSH) is an important factor to 
consider when choosing a Pump. Sufficient NPSH is required at 
the inlet of the Pump to prevent the formation of small bubbles 
in the pump casing which can damage the Pump. This is known 
as cavitation. For a given Pump, the net positive suction head 
required to prevent cavitation, NPSHrequired, is a function of the 
capacity (volumetric flowrate) and speed of the Pump.
In HYSYS, NPSH curves can be specified like regular pump 
curves on the NPSH page.
To add or edit a NPSH curve from the NPSH page:
1. Select the Enable NPSH curves checkbox.
2. Click the Add Curve button, the NPSH Curve property view 
appears.
3. Specify the speed for each curve.
The default values in the Required Data table are provided as 
an example. The variable values must be changed to reflect 
the data of the pump the user wants to simulate. The user 
data is normally provided by the pump manufacturer or by 
the design specifics for the simulation.
The default values in the Optional Curve Shape Data table 
are for a typical pump used in a plant.
 Figure 9.399-82
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Rotating Operations 9-83
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Th4. Enter a capacity and NPSH for two points on the curve. Only 
two points are required for the NPSH curves since:
5. To remove all the data points, click the Erase All button.
6. For each additional curve, repeat steps #2 to #4.
The NPSHrequired value can either be taken from the NPSH curves 
or specified directly in the NPSH required field. To directly 
specify the NPSHrequired, you must first clear the Enable NPSH 
curves checkbox.
NPSHavailable can be explicitly calculated from the flowsheet 
conditions by clicking the Calculate Head button. The 
NPSHavailable is calculated as follows:
where:  
P1 = inlet stream pressure to the pump
Pvap = vapour pressure of the inlet stream
 = density of the fluid
V1 = velocity of the inlet stream
g = gravity constant
(9.39)
 Figure 9.40
(9.40)
NPSHrequired( ) capacity( )log∝log
NPSHavailable
P1 Pvap–
ρg
----------------------
V1
2g
-----
2
⎝ ⎠
⎛ ⎞+=
ρ
9-83
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ThTo prevent pump cavitation the NPSHavailable must be above the 
NPSHrequired. If a pump cavitates in HYSYS, it is modeled by 
scaling the density of the fluid, , randomly between zero and 
one.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
For a Pump unit operation it is strongly recommended that the 
elevation of the inlet and exit nozzles are equal. If you want to 
model static head, the entire piece of equipment can be moved 
by modifying the Base Elevation relative to Ground Elevation 
field.
Inertia Page
The inertia modeling parameters and the frictional loss 
associated with the impeller in the Pump can be specified on this 
page. The HYSYS Dynamics license is required to use the Inertia 
features. 
Electric Motor Page
The Electric Motor page allows you to drive your rotating unit 
operation through the designation of a motor torque versus 
speed curve. These torque vs. speed curves can either be 
obtained from the manufacturer for the electric motor being 
used or from a typical curve for the motor type. For most 
process industry applications, a NEMA type A or B electric motor 
is used. When you use the Electric Motor option the torque (and 
power) generated by the motor is balanced against the torque 
consumed by the rotating equipment.
ρ
Refer to Section 1.3.6 - 
Nozzles Page for more 
information.
Refer to Section 1.6.4 - 
Inertia in the HYSYS 
Dynamic Modeling 
guide for more 
information.9-84
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Th 
The following table lists and describes the objects in the Electric 
Motor page:
The Electric Motor functionality is only relevant in Dynamics 
mode.
The Electric Motor option uses one degree of freedom in your 
dynamic specifications.
The results of the Electric Motor option are presented on the 
Power Page in the Performance Tab of the rotating 
equipment operation.
 Figure 9.41
Object Description
Synchronous 
Speed cell
Allows you to specify the synchronous speed of the 
motor.
Full Load Speed 
cell
Allows you to specify the design speed of the motor.
Full Load Torque 
cell
Allows you to specify the design torque of the motor.
Full Load Power 
cell
Allows you to specify the design power of the motor.
Gear Ratio cell Allows you to manipulate the gear ratio. The gear ratio 
is the rotating equipment’s speed divided by the motor 
speed.
Motor Inertia cell Allows you to specify the motor inertia.
Motor Friction 
Factor cell
Allows you to specify the motor friction factor.
User Electric 
Motor checkbox
Allows you to toggle between using or ignoring the 
electric motor functionality.9-85
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9-86 Pump
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ThTheory
The definition of torque is found from the following equation:
where:  
P = power consumption (kW)
T = torque (Nm)
 = synchronous speed (rpm)
Speed vs Torque 
Curve button
Allows you to view the plot and specify the data in the 
Speed vs. Torque Curve Property View.
Size Inertia 
button
Allows you to calculate the inertia based on the 
following equation:
where:
I = inertia ( )
P = full load power of the motor (kW)
N = full load speed of the motor (rpm/1000)
Simple radio 
button
Allows you to select the Simple model for the 
modelling option.
Breakdown radio 
button
Allows you to select the Breakdown model for the 
modelling option.
Electric Brake 
checkbox
Allows you to model the torque force on the rotating 
equipment simply by changing the sign of the 
produced torque value.
Gearing 
checkbox
Allows the gear ratio to be updated during integration.
A zero value for the gear ratio indicates a decoupling of 
the equipment.
(9.41)
Object Description
I 0.0043 P
N
---⎝ ⎠
⎛ ⎞ 1.48
=
kg m3⋅
Refer to Operation 
Model section for more 
information.
P T ω 2 π×××
1000 60×
--------------------------------=
ω
9-86
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Rotating Operations 9-87
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ThThe synchronous electric motor speed can be found from:
where:  
f = power supply frequency (Hz), typically either of 50 or 60
p = number of poles on the stator 
The number of poles is always an even number of 2, 4, 6, 8, 10, 
and so forth. In North America, common motor speeds are 
always 3600, 1800, 1200, 900, 720, and so forth.
The relationships of inertia and friction loss in the total energy 
balance are the same as for the pump and compressor 
operations.
Operation Model
There are three ways to use the Electric Motor curve, each with 
progressing rigor.
• Simple Model. The easiest calculation is the Simple 
modelling option (default). This model is useful if you 
just want to model the startup/shutdown transient and 
want to keep the equipment at the fixed full load speed 
once operating. In this mode, once the speed has 
accelerated enough to become larger than the last 
(largest) curve speed value entered, the motor speed 
immediately is set to the full load speed and remains 
there until the motor is turned off. If the process invokes 
a larger torque than the motor curve suggests the motor 
can produce, the speed still remains synchronous and 
remains at its full load value.
• Breakdown Model. The Breakdown modelling option 
allows the speed to reduce if the system torque or 
resistance gets too large. To use this option, the largest 
(last) curve speed value entered should be just less than 
the full load speed value. This provides for a smooth 
transition in operation. You can drop the curve to a lower 
torque than the breakdown torque if desired.
• Simple Model Modified. The third modelling approach 
is to use the Simple model option, but enter the speed vs 
torque curve up to a speed value of 99.99% of the 
synchronous speed. In this case the full load speed 
(9.42)ω 120f
p
----------=9-87
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9-88 Pump
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Thentered is only used, if necessary, to calculate the full 
load torque and is not used otherwise. With this 
approach, the speed vs torque curve must ascend or 
drop from the breakdown torque to approach zero torque 
at 100% speed. For most motor types, this approach is 
nearly vertical (asymptotic). This modelling approach 
allows for the simulation of the slippage of the motor 
speed based upon the actual and current system 
resistance. The operating speed of the motor will then 
move based upon the process model operation. Use a 
near vertical curve to keep a constant speed or level it off 
more to allow greater slip. This performance should be 
predicted by using an accurate manufacturers torque vs 
speed curve.
Speed vs. Torque Curve Property View
The Speed vs. Torque Curve property view displays the data 
curve of speed versus torque in both table and plot format. To 
access the Speed vs. Torque Curve property view, click the 
Speed vs Torque Curve button on the Electric Motor page of 
the Rating tab. 
The speed and torque are not solved simultaneously with the 
pressure flow solution but instead is lagged by a time step. 
You may need to use a smaller time step to ensure accuracy 
and pressure flow solver convergence.
 Figure 9.429-88
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ThThe following table lists and describes the objects available in 
the Speed vs. Torque Curve property view:
Design Page
The Design page allows you to specify the typical or design 
operating capacity, pump speed, and power consumption. 
• Typical operating capacity cell allows you to specify a 
value used to assist pump start up priming when vapor is 
present in the inlet stream. 
• Design Speed cell allows you to specify the speed value 
used for the Auto Pump Curve generation feature and the 
pump inertia sizing.
• Design Power cell allows you to specify the power value 
used for the Auto Pump Curve generation feature and for 
pump inertia sizing.  
The values under the Speed and Torque columns are entered 
as a percent of the Full Load values.
The Speed vs. Torque curve must always contain a 0% speed 
value.
During integration, the current operating point appears on 
the Torque vs. Speed curve.
The maximum table speed cannot be greater than the value 
in the Maximum X value field. The Maximum X value is the 
ratio of the full load speed to the synchronous speed.
Object Description
Maximum X 
value display 
field
Displays the ratio of the full load speed to the 
synchronous speed.
Speed column Allows you to specify speed percentage values you 
want to plot.
Torque column Allows you to specify the torque percentage values 
associated with the speed.
Erase Selected 
button
Allows you to delete the row containing both speed and 
torque percentage values of the selected cell.
Erase All button Allows you to delete all the values in the table.
The HYSYS Dynamics license is required to use the options in 
the Design page.
Refer to Section 1.6.6 - 
Design in the HYSYS 
Dynamic Modeling 
guide for more 
information.9-89
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9-90 Pump
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Th9.3.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
9.3.6 Performance Tab
The Performance tab contains the calculated results of the 
pump.
Results Page
The Results page contains pump head information. The values 
for total head, pressure head, velocity head, Delta P excluding 
static head, total power, friction loss, rotational inertia, and fluid 
power are calculated values.
The Total Head field is used only for dynamic simulation.
 Figure 9.43
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.9-90
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Rotating Operations 9-91
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ThPower Page
The Power page displays the following calculated values:
• pump rotor power variables
• pump rotor torque variables
• electric motor power variables (if applicable)
• electric motor torque variables (if applicable)
• other electric motor data (if applicable)
9.3.7 Dynamics Tab
The Dynamics tab is used only for dynamic simulation. The 
Dynamic tab contains the following pages:
• Specs
• Holdup
• Stripchart
Specs Page
The dynamic specifications of the Pump can be specified on the 
Specs page.
If you are working exclusively in Steady State mode, you are 
not required to change any of the values on the pages 
accessible through the Dynamics tab.
 Figure 9.449-91
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9-92 Pump
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ThIn general, two specifications should be selected in the 
Dynamics Specifications group in order for the Pump operation 
to fully solve. You should be aware of specifications, which may 
cause complications or singularity in the pressure flow matrix. 
Some examples of such cases are:
• The Pressure rise checkbox should not be selected if 
the inlet and exit stream pressures are specified.
• The Speed checkbox should not be selected if the Use 
Characteristic Curves checkbox is not selected.
The possible dynamic specifications are as follows:
Head
The ideal head, h, can easily be defined as a function of the 
isentropic or polytropic work. The relationship is:
where:  
W = ideal pump power
MW = molecular weight of the gas
F = molar flow rate of the inlet stream
g = gravity acceleration
or using Equation (9.34), the head is defined as:
If pump curves are provided in the Curves page of the Rating 
tab, the ideal head can be interpolated from the flow of gas and 
the speed of the pump.
(9.43)
(9.44)
W MW( )Fgh=
h
P2 P1–
ρg
-----------------=9-92
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Rotating Operations 9-93
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ThFluid Head
The Fluid Head is the produced head in units of energy per unit 
mass.
Speed
The rotational speed of the shaft, , driving the Pump can be 
specified.
Efficiency
The efficiency is given as the ratio of the ideal power required by 
the pump to the actual energy imparted to the fluid. The 
efficiency, , is defined as:
The ideal power required by the pump is provided in Equation 
(9.34).
The general definition of the efficiency does not include the 
losses due to the rotational acceleration of the shaft and seal 
losses. Therefore, the efficiency equations in dynamics are not 
different at all from the general efficiency equations defined in 
Section 9.3.1 - Theory.
If pump curves are provided in the Curves page of the Rating 
tab, the efficiency can be interpolated from the flow of gas and 
the speed of the Pump.
Pressure Rise
A Pressure Rise specification can be selected, if the pressure 
drop across the Pump is constant.
(9.45)
ω
η
η W
F MW( ) h2 h1–( )
--------------------------------------=9-93
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9-94 Pump
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ThPower
The duty is defined as the power required to rotate the shaft and 
provide energy to the fluid. The duty has three components: 
The duty should be specified only if there is a fixed rate of 
energy available to be used to drive the shaft.
Capacity
The capacity is defined as the actual volumetric flow rate 
entering the Pump.
Use Characteristic Curves
Select the Use Characteristic Curves checkbox, if you want to 
use the curve(s) specified in the Curves page of the Rating tab. 
If a single curve is specified in a dynamics Pump, the speed of 
the Pump is not automatically set to the speed of the curve. A 
different speed can be specified, and HYSYS extrapolates values 
for head and efficiency.
Pump is acting as turbine
Select the Pump is acting as turbine checkbox, if you want 
the pump to act as a turbine with a pressure drop from inlet to 
outlet.
Duty = Power supplied to the fluid + Power required to 
change the rotational speed of the shaft + Power lost 
due to mechanical friction loss
(9.46)9-94
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Rotating Operations 9-95
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ThLinker Power Loss
Select the Linker Power Loss checkbox, if you want to specify 
the power loss (negative for a power gain) of the linked 
operations. 
Electric Motor
Select the Electric Motor checkbox if you want to use the 
electric motor functionality.
Holdup Page
Typical pumps in actual plants usually have significantly less 
holdup than most other unit operations in a plant. Therefore, the 
volume of the Pump operation in HYSYS cannot be specified, 
and is assumed to be zero on the Holdup page.
Stripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the operation. 
9.4 References
 1 Gas Processors Association. Gas Processors Suppliers Association 
(1998) p.13-1 to p13-20
 2 Campbell M.John. Gas Conditioning and Processing (vol2) 7th edi. 
1994, p213-221
 3 Thorley A. R. D. Fluid Transients in Pipeline Systems. D & L George 
Ltd. England, 1991.
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 
- Stripchart Page/Tab 
for more information.9-95
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Th9-96
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Separation Operations 10-1
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Th10 Separation 
Operations10-1
10.1  Component Splitter ...................................................................... 2
10.1.1  Theory .................................................................................. 2
10.1.2  Component Splitter Property View ............................................ 3
10.1.3  Design Tab ............................................................................ 4
10.1.4  Rating Tab ........................................................................... 10
10.1.5  Worksheet Tab ..................................................................... 10
10.1.6  Dynamics Tab ...................................................................... 10
10.2  Separator, 3-Phase Separator, & Tank ....................................... 12
10.2.1  Theory ................................................................................ 14
10.2.2  Separator General Property View ............................................ 17
10.2.3  Design Tab .......................................................................... 18
10.2.4  Reactions Tab....................................................................... 21
10.2.5  Rating Tab ........................................................................... 22
10.2.6  Worksheet Tab ..................................................................... 45
10.2.7  Dynamics Tab ...................................................................... 45
10.3  Shortcut Column ........................................................................ 51
10.3.1  Shortcut Column Property View .............................................. 51
10.3.2  Design Tab .......................................................................... 52
10.3.3  Rating Tab ........................................................................... 55
10.3.4  Worksheet Tab ..................................................................... 55
10.3.5  Performance Tab .................................................................. 55
10.3.6  Dynamics Tab ...................................................................... 56
10.4  References................................................................................. 56
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10-2 Component Splitter
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Th10.1 Component Splitter
With a Component Splitter, a material feed stream is separated 
into two component streams based on the parameters and split 
fractions that you specify. You must specify the fraction of each 
feed component that exits the Component Splitter into the 
overhead product stream. Use it to approximate the separation 
for proprietary and non-standard separation processes that are 
not handled elsewhere in HYSYS.
10.1.1 Theory
The Component Splitter satisfies the material balance for each 
component:
where:  
fi = molar flow of the ith component in the feed
ai = molar flow of the ith component in the overhead
bi = molar flow in the ith component in the bottoms
The molar flows going to the overhead and bottoms are 
calculated as:
where:  
xi = split, or fraction of component i going to the overhead
Once the composition, vapour fraction, and pressure of the 
outlet streams are know, a P-VF flash is performed to obtain the 
temperatures and heat flows.
fi = ai + bi (10.1)
ai = xi fi (10.2)
bi = (1-xi ) fi (10.3)10-2
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Separation Operations 10-3
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ThAn overall heat balance is performed to obtain the energy 
stream heat flow:
where:  
hE = enthalpy of unknown energy stream
hF = enthalpy of feed stream
hO = enthalpy of overhead stream
hB = enthalpy of bottoms stream
10.1.2 Component Splitter 
Property View
There are two ways that you can add a Component Splitter to 
your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Short Cut Columns radio button.
3. From the list of available unit operations, select the 
Component Splitter model.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Component Splitter icon. 
hE = hF - hO - hB (10.4)
Component Splitter icon10-3
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10-4 Component Splitter
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ThThe Component Splitter property view appears.
10.1.3 Design Tab
The Design tab contains the following pages: 
• Connections
• Parameters
• Splits
• TBP Cut Point
• User Variables
• Notes
Each of the pages are discussed in the following sections.
 Figure 10.110-4
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Separation Operations 10-5
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ThConnections Page
You can specify an unlimited number of inlet streams to the 
Component Splitter on the Connections page. You must specify 
the overhead outlet stream, bottoms outlet stream, and an 
unlimited number of energy streams.
One of the attached energy streams should have an unspecified 
energy value to allow the operation to solve the energy balance.
Parameters Page
The Parameters page displays the stream parameters. You must 
specify the stream parameters, which include the vapour 
fraction, pressure of the overhead stream, and pressure of the 
bottoms stream.
 Figure 10.2
 Figure 10.310-5
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10-6 Component Splitter
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ThTo specify the Component Splitter parameters:
1. Click one of the following radio buttons to calculate the 
outlet stream parameters:
- Calculate Equal Temperatures – HYSYS calculates 
equal temperatures for both the Overhead and 
Bottoms streams. You cannot select this option if you 
have multiple overhead streams.
- Use Stream Flash Specifications – HYSYS uses the 
stream specifications to calculate the outlet stream 
conditions.
2. Click one of the following radio buttons to calculate the 
Overhead and Bottoms stream pressures:
- Use Stream Pressure Specifications – You must 
supply the pressure for each of the outlet streams.
- Equalize All Stream Pressures – HYSYS gives all 
the attached streams the same pressure after one of 
the attached streams is known. 
- Use Lowest Feed Pressure for All Products – 
HYSYS assigns the lowest inlet pressure to the outlet 
stream pressure. All but one outlet stream pressure 
must be known.
To avoid consistency errors, remember to delete relevant 
specifications when chosing your Component Splitter 
parameters.
Splits Page
The Splits page allows you to specify the separation fraction of 10-6
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Separation Operations 10-7
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Ththe outlet streams. 
The Splits, or separation fractions ranging from 0 to 1, must be 
specified for each component in the overhead stream exiting the 
Component Splitter. The quantity in the bottoms product is set 
once the overhead fraction is known. 
The two buttons on the Splits page, All 1 and All 0, allow you to 
specify overhead fractions of one (100%) or zero (0%), 
respectively, for all components. These buttons are useful if 
many components are leaving entirely in either the overhead 
stream or bottoms stream.
For example, if the majority of your components are going 
overhead, simply click the All 1 button, rather than 
repeatedly entering fractions of 1. Then, correct the splits 
appropriately for the components not leaving entirely in the 
overhead.
 Figure 10.410-7
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10-8 Component Splitter
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ThTBP Cut Point Page
The TBP Cut Point page allows you to specify the compositions 
of the product streams by providing the TBP Cut Point between 
the streams, and assuming that there is sharp separation at the 
cut point. 
On the TBP Cut Point page, the upper table allows you to specify 
the initial TBP Cut Point on the Feed for each product stream 
except for the overhead. The Initial Cut Point values are 
expressed in temperature and they are listed in ascending order. 
Consecutive streams can have the same Initial Cut Point value, 
implying that the second or subsequent stream has zero flow.
The bottom table allows you to specify the split fraction for each 
component in the stream. The split fraction values are also 
available on the Splits page of the Design tab.
Pure components are distributed according to their NBP (Natural 
Boiling Point) while the TBP (True Boiling Point) of the pure 
 Figure 10.5
You can specify a temperature cut point of 0 K and higher.
The TBP Cut Point Page is designed for streams with 
hypothetical components.10-8
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Separation Operations 10-9
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Thcomponents defines the boundaries of distribution. The NBP for 
each component is displayed in the NBP table for reference.
The TBP Cut Point page is designed for handling streams that 
carry hypocomponents. The hypocomponents are treated as a 
continuum and they are distributed according to their FBP (Final 
Boiling Point). The FBP of each hypocomponent is first calculated 
by sorting the NBP of the hypocomponents in ascending order. 
Then with the sorted order, the FBP of the last hypocomponent 
is calculated as follows:
The FBPs for other hypocomponents is calculated by:
The hypocomponents are then distributed according to where 
the cut point lies. The boiling range for each hypocomponent is 
defined by the FBP of the previous component to the FBP of the 
current component. The boiling range for each product stream is 
from its Initial TBP Cut Point to the Initial TBP Cut Point of the 
next stream.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
(10.5)
(10.6)
FBPlast NBPlast NBPlast NBPlast 1––( )+=
FBPi
NBPi NBPi 1++
2
-------------------------------------------=
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.10-9
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10-10 Component Splitter
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Th10.1.4 Rating Tab
You cannot provide any information for the Component Splitter 
on the Rating tab when in steady state. 
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles.
10.1.5 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
10.1.6 Dynamics Tab
Information available on this page is relevant only to cases in 
Dynamic mode. The Dynamics tab consists of the Specs page.
The PF Specs page is relevant to dynamics cases only.
For more information, 
refer to Section 1.3.6 - 
Nozzles Page.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.10-10
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Separation Operations 10-11
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ThSpecs Page
The Specs page contains information regarding pressure 
specifications of the streams.
The Equal Pressures checkbox allows you to propagate the 
pressure from one stream to all others. If you want to equalize 
the pressures you have to free up the pressure specs on the 
streams that you want the pressure to be propagated to.
The Vessel Volume is also specified on this page. This volume is 
only used to affect the compositional affects in this operation. 
The Pressure - Flow and hydraulics are not affected by this 
value. This volume is only a simplified and synthetic way of 
getting some lag in the compositional affects. The thermal state 
(temperature and enthalpy) of the outlet streams may or may 
not be affected by this value depending on the other 
specifications of this operation. For example, if you have 
specified the outlet stream temperatures directly, then this 
volume has no affect, on the other hand if the operation is doing 
some flash with an external duty (of value zero or otherwise), 
then this volume has an affect.
 Figure 10.610-11
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10-12 Separator, 3-Phase Separator, & 
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Th10.2 Separator, 3-Phase 
Separator, & Tank
The property views for the Separator, 3-Phase Separator, and 
Tank are similar, therefore, the three unit operations are 
discussed together in this section. 
There is an Operation Type toggle option on the Parameters 
page of the Design tab that allows you to easily switch from one 
of these operations to another. For example, you may want to 
change a fully defined Separator to a 3-Phase Separator. Simply, 
select the appropriate radio button in the Operation Type toggle 
option. The only additional information required would be to 
identify the additional liquid stream. All of the original 
characteristics of the operation (Parameters, Reactions, and so 
forth) are retained. 
The key differences in the three separator operations are the 
stream connections (related to the feed separation), which are 
described in the table below.
All information in this section applies to the Separator, the 3-
Phase Separator, and the Tank operation, unless indicated 
otherwise.
Unit Operation Description
Separator Multiple feeds, one vapour and one liquid product 
stream. In Steady State mode, the Separator divides 
the vessel contents into its constituent vapour and 
liquid phases.
3-Phase 
Separator
Multiple feeds, one vapour and two liquid product 
streams. The 3-Phase Separator operation divides the 
vessel contents into its constituent vapour, light liquid, 
and heavy liquid phases.
Tank Multiple feeds, one liquid and one vapour product 
stream. The Tank is generally used to simulate liquid 
surge vessels.10-12
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Separation Operations 10-13
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ThIn Dynamic mode, the following unit operations all use the 
holdup model and therefore, have many of the same properties. 
Vessel operations in HYSYS have the ability to store a significant 
amount of holdup.
The key differences in the vessel operations are outlined in the 
table below.
Every dynamic vessel operation in HYSYS has some common 
features including:
• The geometry of the vessel and the placement and 
diameter of the attached feed and product nozzles have 
physical meaning.
• A heat loss model which accounts for the convective and 
conductive heat transfer that occurs across the vessel 
wall.
• Various initialization modes which allow you to initialize 
the vessel at user-specified holdup conditions before 
running the integrator.
• Various Heater types which determine the way in which 
heat is transferred to the vessel operation.
Unit Operation Description
Separator The Separator can have multiple feeds. There are two 
product nozzles:
• liquid
• vapour.
3-Phase 
Separator
The 3-Phase Separator can have multiple feeds. There 
are 3 product nozzles: 
• light liquid
• heavy liquid
• vapour.
Tank The Tank can have multiple feeds. There are two 
product nozzles which normally removes liquid and 
vapour from the Tank. 
Condenser The condenser has one vapour inlet stream. The 
number and phase of each exit stream depends on the 
type of condenser. The condenser has a unique 
method of calculating the duty applied to its holdup.
Reboiler The reboiler has one liquid inlet stream. The reboiler 
can have a number of liquid and vapour exit streams.
Reactors Reactor operations can have multiple inlet and exit 
streams.
Heat Exchanger 
(Simple Rating 
Model, Detailed)
A shell or tube with a single pass in the heat exchanger 
unit operation can be modeled with a liquid level. Both 
the shell and tube sides of the heat exchanger have 
one inlet and one exit stream.10-13
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10-14 Separator, 3-Phase Separator, & 
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Th10.2.1 Theory
A P-H flash is performed to determine the product conditions 
and phases. The pressure at which the flash is performed is the 
lowest feed pressure minus the pressure drop across the vessel. 
The enthalpy is the combined feed enthalpy plus or minus the 
duty (for heating, the duty is added; for cooling, the duty is 
subtracted).
As well as standard forward applications, the Separator and 3-
Phase Separator have the ability to back-calculate results. In 
addition to the standard application (completely defined feed 
stream(s) being separated at the vessel pressure and enthalpy), 
the Separator can also use a known product composition to 
determine the composition(s) of the other product stream(s), 
and by a balance the feed composition.
In order to back-calculate with the Separator, the following 
information must be specified:
• One product composition.
• The temperature or pressure of a product stream.
• Two (2-phase Separators) or three (3-phase Separators) 
flows.
If you are using multiple feed streams, only one feed stream 
can have an unknown composition in order for HYSYS to 
back-calculate.10-14
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Separation Operations 10-15
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ThEnergy Balance
In Steady State mode Separator energy balance is defined 
below:
where:
Hfeed = heat flow of the feed stream(s)
Hvapour = heat flow of the vapour product stream
Hlight = heat flow of the light liquid product stream
Hheavy = heat flow of the heavy liquid product stream
Physical Parameters
The Physical Parameters associated with this operation are the 
pressure drop across the vessel and the vessel volume. 
The pressure drop across the vessel is defined as:
where:
P = vessel pressure
Pv = pressure of vapour product stream
Pl = pressure of liquid product stream(s)
Pfeed = pressure of feed stream
the pressure is assumed to be the lowest pressure of all 
the feed streams
 = pressure drop in vessel
Phead = pressure of the static head
(10.7)
The default pressure drop across the vessel is zero.
(10.8)
Hfeed Duty± Hvapour Hheavy Hlight+ +=
P Pl Pfeed ΔP– Phead Pv+= = =
ΔP10-15
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10-16 Separator, 3-Phase Separator, & 
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ThThe vessel volume, together with the set point for liquid level/
flow, defines the amount of holdup in the vessel. The amount of 
liquid volume, or holdup, in the vessel at any time is given by 
the following expression
where:
PV(%Full) = liquid level in the vessel at time t
Ideal vs. Real
In ideal separators, complete/perfect separation between the 
gas and liquid phases is assumed.
In real world separators, separation is not perfect: liquid can 
become entrained in the gas phase and each liquid phase may 
include entrained gas or entrained droplets of the other liquid 
phase. Recent years have seen increasing use of vessel internals 
(for example, mesh pads, vane packs, weirs) to reduce the carry 
over of entrained liquids or gases.
By default the HYSYS separators are ideal separators, however, 
you can modify the separators to model imperfect separation by 
using the HYSYS Real Separator capabilities. The real separator 
offers you a number of advantages: 
• Carry Over options so that your model matches your 
process mass balance or separator design specifications.
• Options to predict the effect of feed phase dispersion, 
feed conditions, vessel geometry, and inlet / exit devices 
on carry over.
(10.9)
The Vessel Volume is necessary in steady state when 
modeling a Reactor (CSTR), as it determines the residence 
time.
Holdup Vessel Volume PV %Full( )
100
----------------------------×=
Refer to Section 10.2.5 
- Rating Tab for 
information on the 
options used to configure 
a real separator.10-16
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Separation Operations 10-17
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Th10.2.2 Separator General 
Property View
There are two ways that you can add a Separator, 3 -Phase 
Separator, or Tank to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Vessels radio button.
3. From the list of available unit operations, select the 
Separator, 3 Phase Separator, or Tank.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Separator icon or 3 Phase Separator icon 
or Tank icon. 
The Separator or 3 Phase Separator or Tank property view 
appears.  
 Figure 10.7
Separator icon
3-Phase Separator icon
Tank icon10-17
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10-18 Separator, 3-Phase Separator, & 
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Th10.2.3 Design Tab
The Design tab contains options for configuring the separator 
operation. 
Connections Page
The Connections page allows you to specify the streams flowing 
into and out of the separator operation, the name of the 
separator operation, and the fluid package associated to the 
separator operation. 
Depending on the type of heat transfer you want to make 
available for the separator operation, the options available in the 
Connections page varies. You are required, however, to always 
specify the following variables:
• Name of the separator operation
• Name of the feed streams
• Name of the vapor product stream
• Name of the liquid product stream(s)
• Name of the fluid package of the separator operation
If you want to use the Separator as a reactor, you can either 
install a Separator or choose General Reactor from the 
UnitOps property view.
Any of the HYSYS separator operations accept multiple feed 
streams, as well as an optional energy stream.10-18
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ThThe figure below shows the Connections pages for the three 
separator operations:
 Figure 10.8
Three Phase Separator with energy stream attached.
Separator with kettle reboiler or chiller attached. Tank with no energy stream attached.10-19
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ThParameters Page
The Parameters page allows you to specify the pressure drop 
across the vessel. 
The following table lists and describes the options available in 
this page:    
 Figure 10.9
Object Description
Inlet cell Allows you to specify the pressure difference across 
the vessel.
Vapour outlet 
cell
Allows you to specify the static head pressure of the 
vessel.
Volume Field Allows you to specify the volume of the vessel. The 
default vessel volume is 2 m3.
Liquid Volume 
Display Field
Not set by the user. The Liquid Volume is calculated 
from the product of the Vessel Volume and Liquid Level 
fraction.
Liquid Level SP 
Field
Allows you to specify the starting point of the liquid 
level in the vessel. This value is expressed as a 
percentage of the Full (Vessel) Volume.
Type Group Allows you to toggle between the Separator, 3-Phase 
Separator, and Tank by clicking the appropriate radio 
button.
If you toggle from a 3 Phase Separator operation to a 
Separator or Tank operation, you permanently lose the 
heavy liquid stream connection. If you change back to the 3 
Phase Separator, you have to reconnect the heavy liquid 
stream.10-20
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
10.2.4 Reactions Tab
The Reactions tab contains options for applying chemical 
reactions that can take place in the vessel.
Results Page
The Results page allows you to attach a reaction set to the 
Separator, 3-Phase Separator, or Tank Operations. 
If you select an alternate unit, your value appears in the face 
plate using HYSYS display units.
 Figure 10.10
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.10-21
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ThIn the Reaction Set drop-down list, select the reaction set you 
want to use. 
Reaction and component information can also be examined in 
the Reaction Results group. Select the Reaction Balance radio 
button to view the total inflow, total reaction, and total outflow 
for all of the components in the reaction. 
Select the Reaction Extents radio button to view the Percent 
Conversion, Base Component, Equilibrium Constant, and 
Reaction Extent. You can also view information for specific 
reactions by clicking the View Global Rxn button.
10.2.5 Rating Tab
The Rating tab includes options relevant in both Steady State 
and Dynamics modes. The options available are:
• Configuring and calculating the separator’s vessel size.
• Specifying and calculating heat loss.
• Configuring level taps to observe relative levels of 
different liquid phases.
• Specifying the PV work term contribution.
• Configuring and calculating the Carry Over model.
Sizing Page
You can define the geometry of the unit operation on the Sizing 
page. Also, you can indicate whether or not the unit operation 
has a boot associated with it. If it does, then you can specify the 
boot dimensions.
You must provide the following information for the separator 
operation when working in Dynamics mode:
• vessel geometry
• nozzle geometry
• heat loss10-22
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ThAfter you specified the vessel’s dimension information in the 
appropriate field, click the Quick Size button to initiate the 
HYSYS sizing calculation for the vessel.
Vessel Geometry
In the Geometry group, you can specify the vessel orientation, 
shape, and volume. The geometry of the vessel is important in 
determining the liquid height in the vessel. 
There are four possible vessel shapes as described in the table 
below.
 Figure 10.11
Vessel Shape Description
Flat Cylinder A cylindrical shape vessel that is available for either 
horizontal or vertical oriented vessel. You can either 
specify the total volume or any two of the following for 
the vessel:
• total volume
• diameter
• height (length)
If only the total cylindrical volume of the vessel is 
specified, the height to diameter ratio is defaulted as 
3:2.
Sphere A sphere shape vessel that is available for either 
horizontal or vertical oriented vessel. You can either 
specify the total volume or the diameter of the sphere.10-23
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ThThe liquid height in a vertical cylindrical vessel varies linearly 
with the liquid volume. There is a nonlinear relationship between 
the liquid height, and the liquid volume in horizontal cylindrical 
and spherical vessels.
Weir
A weir can be specified for the horizontal flat cylinder separator 
by selecting the Enable Weir checkbox and clicking the Weir 
button. The Initial Holdup property view appears. 
Ellipsoidal 
Cylinder
A ellipsoidal cylindrical shape vessel that is only 
available for horizontal oriented vessel. You can either 
specify the total volume or any three of the following 
for the vessel:
• total volume
• diameter
• length
• ellipsoidal head height
If only the total cylindrical volume of the vessel is 
specified, the height to diameter ratio is defaulted as 
3:2.
If the diameter or length is already specified, the only 
other variable that can be specified is the Ellipsoidal 
Head Height.
Hemispherical 
Cylinder
A hemispherical cylindrical shape vessel that is only 
available for horizontal oriented vessel. You can either 
specify the total volume or any two of the following for 
the vessel:
• total volume
• diameter
• length
If only the total cylindrical volume of the vessel is 
specified, the height to diameter ratio is defaulted as 
3:2.
The Enable Weir checkbox is only available for Flat Cylinder 
vessel shape option.
Vessel Shape Description10-24
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ThThe Initial Holdup property view allows you to specify the weir 
height and position. The weir position is the distance the weir is 
from the vessel feed side. HYSYS calculates the Levels and 
Phase Moles in each chamber using the specified values for the 
weir height and position.
When HYSYS simulates, the weir has two volumes inside the 
Separator, called chamber 1 and chamber 2; but there is still 
only one enhanced holdup volume and moles as far as the 
pressure flow solver is concerned. This means that the 
compositions and properties of the phases in the two volumes 
are the same.
 Figure 10.12
 Figure 10.1310-25
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ThBoot Geometry
Any vessel operation can be specified with a boot. A boot is 
typically added when two liquid phases are present in the 
holdup. Normally, the heavy liquid exits from the boot exit 
nozzle. The lighter liquid can exit from another exit nozzle 
attached to the vessel itself. 
In HYSYS, a boot can be added to the vessel geometry by 
selecting the This Separator has a Boot checkbox. The boot 
height is defaulted to one third the vessel height. The boot 
diameter is defaulted to one third the vessel diameter.
Nozzles Page
The Nozzles page contains information regarding the elevation 
and diameter of the nozzles. 
Unlike steady state vessel operations, the placement of feed and 
product nozzles on a dynamic vessel operation has physical 
 Figure 10.14
The HYSYS Dynamics license is required to use the Nozzle 
features found on the Nozzles page.10-26
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Thmeaning. The composition of the exit stream depends on the 
exit stream nozzle location and diameter in relation to the 
physical holdup level in the vessel. 
• If the product nozzle is located below the liquid level in 
the vessel, the exit stream draws material from the liquid 
holdup. 
• If the product nozzle is located above the liquid level, the 
exit stream draws material from the vapour holdup. 
• If the liquid level sits across a nozzle, the mole fraction of 
liquid in the product stream varies linearly with how far 
up the liquid is in the nozzle. 
Essentially, all vessel operations in HYSYS are treated the same. 
The compositions and phase fractions of each product stream 
depend solely on the relative levels of each phase in the holdup 
and the placement of the product nozzles. So, a vapour product 
nozzle does not necessarily produce pure vapour. A 3-Phase 
Separator may not produce two distinct liquid phase products 
from its product nozzles.
Heat Loss Page
The Heat Loss page contains heat loss parameters which 
characterize the amount of heat lost across the vessel wall. 
 Figure 10.1510-27
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ThIn the Heat Loss Model group, you can select one of the radio 
buttons to use as a model:
• Simple
• Detailed
• None (no heat loss through the vessel walls).
The Simple and Detailed heat loss models are discussed in the 
following sections.
Simple Model
The Simple model allows you to either specify the heat loss 
directly or have the heat loss calculated from specified values: 
• Overall U value
• Ambient Temperature
The heat transfer area, A, and the fluid temperature, Tf, are 
calculated by HYSYS. The heat loss is calculated using:
where:
U = overall heat transfer coefficient
A = heat transfer area
TAmb = ambient temperature
For a Separator, the parameters available for the Simple model 
Q = UA(Tf - Tamb) (10.10)10-28
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Thare shown in the figure below:
The simple heat loss parameters are:
• Overall Heat Transfer Coefficient
• Ambient Temperature
• Overall Heat Transfer Area
• Heat Flow
The Heat Flow is calculated as follows:
where:
U = overall heat transfer coefficient
A = heat transfer area
TAmb = ambient temperature
T = holdup temperature
As shown, Heat Flow is defined as the heat flowing into the 
vessel. The heat transfer area is calculated from the vessel 
geometry. The ambient temperature, TAmb, and overall heat 
transfer coefficient, U, can be modified from their default values 
shown in red.
 Figure 10.16
Heat Flow = UA(TAmb - T) (10.11)10-29
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ThDetailed Model
The Detailed model allows you to specify more detailed heat 
transfer parameters. The HYSYS Dynamics license is required to 
use the Detailed Heat Loss model found on the Heat Loss page. 
Level Taps Page
Since the contents in a vessel can be distributed in different 
phases, the Level Taps page allows you to monitor the level of 
liquid and aqueous contents that coexist within a specified zone 
in a tank or separator. 
Level Taps Specifications (Dynamics)
The Level Tap Specifications (Dynamics) group allows you to 
The information available on this page is relevant only to 
dynamics cases.
You can also define Level Taps for the lowest stage of a 
distillation column, as long as it is a Sump type. In the 
column subflowsheet, column property view, use the rating 
tab, level taps page.
 Figure 10.17
Refer to Section 1.6.1 - 
Detailed Heat Model in 
the HYSYS Dynamic 
Modeling guide for more 
information.10-30
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Thspecify the boundaries to be monitored within the vessel, and to 
normalize that section in a desired scale.
A level tap can be specified for any horizontal or vertical vessel 
by clicking the New Level Tap button. 
To set the boundaries of the section concerned, specify the 
following fields:
By default, a new level tap is set to the total height of the 
vessel, and the height is normalized in percentage (100-0). 
Calculated Level Taps Values (Dynamics)
The level of liquid and aqueous are displayed in terms of the 
output normalization scale you specified. Whenever the level of 
a content exceeds PV High, HYSYS automatically outputs the OP 
High value as the level of that content. If the level is below the 
PV Low, HYSYS outputs the OP Low value. The levels displayed 
You can add/configure multiple level taps.
Field Description
Level Tap Name of the level tap.
PV High (m) Upper limit of the section to be monitored. It is expressed 
in meters.
PV Low (m) Lower limit of the section to be monitored. It is expressed 
in meters.
OP High Upper limit of the output of the normalization scale.
OP Low Lower limit of the output of the normalization scale.
The normalization scale can be negative values. In some 
cases, the output normalization scale is manually set 
between -7% to 100% or -15%-100% so that there is a 
cushion range before the level of the content becomes 
unacceptable (in other words, too low or too high).
All the upper limit specifications should not be smaller than 
or equal to the lower limit specifications and vice versa; 
otherwise no calculations will be performed.10-31
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Thare always entrained within the normalized zone.
Option Page
The Options page allows you to specify and enable the PV Work 
Term Contribution. 
The PV Work Term Contribution is expressed in percent. It is 
approximately the isentropic efficiency. A high PV work term 
contribution value results in lower pressures, and temperatures. 
The PV work term contribution value should be between 87% to 
98%.
C.Over Setup Page
The C.Over Setup page allows you to modify the separator 
operation from an ideal model to a real model. 
To achieve a real model separator, the C. Over Setup page 
enables you to configure the carry over effect in real separator 
operations. Carry over refers to the conditions when the liquid 
gets entrained in the vapour phase and/or when the gas gets 
entrained in the liquid phase. The effect is mainly caused by the 
disturbances created as the inlet stream enters the vessel. 
In HYSYS, the carry over effect is modelled using the 
entrainment fraction in the feed or product stream, or using the 
 Figure 10.1810-32
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Thavailable correlations that calculate carry over based on the 
vessel configuration.
On the C. Over Setup page, you can select the type of carry over 
calculation model by clicking one of the following four radio 
buttons:
• None (indicates that there is currently no carry over 
model applied to the associated vessel).
• Feed Basis
• Product Basis
• Correlation Based
There are two checkboxes available at the bottom of the page:
• Carry Over to Zero Flow Streams. When you select 
this checkbox, the calculated carry over will be added to 
the product stream even if it has no flow.
• Use PH Flash for Product Streams. When you select 
this checkbox, you apply a PH flash calculation to the 
product streams. This option is slower but it may be 
required to eliminate inconsistencies when one product 
flow is much less than the others.
These two checkboxes are available in the Feed Basis, Product 
Basis, and Correlation Based models.
The Feed Basis, Product Basis, and Correlation Based models 
are discussed in the following sections.
Feed Basis Model
The Feed Basis Model allows you to specify the entrainment of 
each phase in each product as a fraction of the feed flow of the 10-33
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Thphase.
There are six types of carry over flow (in the feed and product 
streams) available for you to specify:
• Light liquid in gas
• Heavy liquid in gas
• Gas in light liquid
• Heavy liquid in light liquid
• Gas in heavy liquid
• Light liquid in heavy liquid
The fractions containing non-zero values indicates the product 
streams exiting the separator will have multiple liquid and gas 
phases. For example, if you specify Fraction of Feed as 0.1 for 
light liquid in gas, this means that 10 mol% of the light liquid 
phase in the feed will be carried over into the gas product 
leaving the separator. As a result the gas product vapour 
fraction will be less than 1.0 and contain a liquid phase. 
 Figure 10.19
The terms light liquid and heavy liquid refer to oil and water, 
respectively. No assumptions are made as to the actual 
composition of the two liquid phases.10-34
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ThProduct Basis Model
The Product Basis model allows you to specify the carry over 
entrainment in the product streams on fraction or flow basis.
You can select the desired basis by clicking on one of the 
following radio buttons in the Specification By group:
• Fraction. Allows you to specify the entrainment in the 
product stream as a fraction. The fraction basis is 
selected from the Basis drop-down list and may be either 
Mole, Mass, Liq.Volume or Actual Volume.
• Flow. Allows you to specify the entrainment in the 
product streams as a flow. The flow basis may be 
specified using the Flow Basis drop-down list. The 
options are Mole, Mass, Liq.Volume or Actual volume.
There are six types of carry over flow (in the feed and product 
streams) available for you to specify:
• Light liquid in gas
• Heavy liquid in gas
• Gas in light liquid
• Heavy liquid in light liquid
• Gas in heavy liquid
 Figure 10.2010-35
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Th• Light liquid in heavy liquid
For example, if you specify Frac in Product (Mole Basis) as 0.1 
for the light liquid in gas, this means that the gas product will 
contain 10 mol% light liquid. 
In Steady State mode, if a phase is missing from the feed 
stream, selecting the Use 0.0 as product spec if phase feed 
flow is zero allows the separator to continue to calculate the 
carry over effect (in this example, carry over model calculation 
ignores any product fraction or flow specification for that 
phase).
In Dynamics mode, the Use 0.0 as product spec if phase 
feed flow is zero feature is automatically and always active.
Correlation Based Model
The Correlation Based model allows you to calculate the 
expected carry over based on the configuration of the vessel, 
the feed conditions, and the operating conditions. 
The options available in the Correlation Based model allows you 
to configure the type of the correlation, dimensions and 
geometry of vessel, pressure drop methods, and nozzle location.
The terms light liquid and heavy liquid refer to oil and water, 
respectively. No assumptions are made as to the actual 
composition of the two liquid phases.10-36
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ThCorrelation Setup
The Correlation Setup group allows you to select the Correlation 
Calculation Type, and how you want to apply the correlation. 
• You can apply one correlation for all of the carry over 
calculations by clicking on the Overall Correlation radio 
button. 
• If you want to select a different correlation for each carry 
over calculation steps (Inlet Device, Gas/Liq Separation, 
Liq/Liq Separation, and Vapour Exit Device), you can 
select the Sub Calculations radio button to activate the 
appropriate options.
 Figure 10.2110-37
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ThA schematic of these steps is shown in the figure below: 
For example, if the Generic correlation is used for the 
Inlet device and ProSeparator is used for primary L-L and 
G-L separation calculations, then the user supplied data 
for the generic inlet calculations (in other words, inlet 
split and Rossin Rammler parameters) will be used to 
 Figure 10.22
Feed Gas Product
Light Liquid Product
Heavy Liquid Product
Oil/Gas
Water/Gas
Inlet 
Calculations
Oil distribution 
in Gas
Water distribution 
in Gas
Gas distribution 
in Oil
Water distribution 
in Oil
Gas distribution 
in Water
Oil distribution 
in Water
Oil/Gas
Water/Gas
Primary Gas-
Liquid 
Separation
Gas/Oil
Water/Oil
Gas/Water
Oil/Water
Primary Liquid-
Liquid 
Separation Gas distribution 
in Oil
Water distribution 
in Oil
Gas distribution 
in Water
Oil distribution 
in Water
Gas/Oil
Water/Oil
Gas/Water
Oil/Water
Oil distribution 
in Gas
Water distribution 
in Gas
Oil/Gas
Water/Gas
Secondary Gas-
Liquid 
Separation
Oil distribution 
in Gas
Water distribution 
in Gas
Only those parts of the correlation in use that apply to the 
particular sub-calculation will be used.10-38
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Separation Operations 10-39
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Thgenerate the inlet droplet dispersion. The ProSeparation 
primary separation calculations will then be performed 
using this inlet dispersion. As ProSeparator correlations 
will not be used to calculate the inlet conditions, any 
ProSeparator inlet setup data is ignored. Likewise, any 
critical droplet sizes entered in the Generic correlation 
will be ignored as the ProSeparator is being used for the 
primary separation calculations.
There are three correlations available: Generic, Horizontal 
Vessel, and ProSeparator. After you have selected the type of 
correlation, you can click on the View Correlation button to 
view its calculation parameters.
• Generic
The Generic correlation provides a general correlation for 
generating the phase dispersions in the feed and defining 
the separation criteria. It is a generic calculation that is 
independent of the vessel dimensions, geometry, and 
operating levels.
For the Inlet Calculations, you must define the 
percentage of each feed phase dispersed in each other 
phase. You must also define the maximum droplet sizes 
and Rosin Rammler index for each dispersion. The 
dispersions are then calculated using Rosin Rammler 
methods to give the amount of each phase in each 
droplet size range.
For the rest of the carry over calculation, all droplets 
smaller than a user-specified critical droplet size are 
assumed to be carried over.
The Generic correlation can be used for gas-liquid, liquid-
liquid, and gas exit separation calculations. You must 
define the critical droplet size for each type of separation. 
Any droplets that are smaller than the specified critical 
droplet size will be carried over; the droplets that are 
larger than the critical droplet size will be separated.
• Horizontal Vessel1 2 3
The Horizontal Vessel correlations were developed for a 
horizontal three-phase separator.
For the Inlet Calculations, the correlations calculate the 
six types of dispersions in the feed according to an 
assumed efficiency of a user-defined inlet device, and 
user-defined dispersion fractions (termed Inlet Hold 
up; these parameters are found on the General page in 
the Setup tab of the Horizontal Vessel Correlation 
property view). The droplet distribution of the dispersed 
phase(s) is then calculated using user-supplied Rosin-
Rammler parameters just as for the Generic correlation.10-39
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ThThe Primary Gas-Liquid Separation is calculated from the 
settling velocities for each liquid (light and heavy) 
droplet size in the gas phase and the residence time for 
the gas in the vessel. A droplet is carried over if the 
vertical distance travelled during its residence in the 
vessel is less than the vertical distance required to rejoin 
its bulk phase.
The Primary Liquid-Liquid Separation is also calculated 
using settling velocities for each droplet of liquid or gas 
in the liquid phases and residence time for each liquid 
phase. The settling velocities are calculated using the 
GPSA correlations for all dispersions, except for the 
water in oil dispersion for which the settling velocity is 
calculated by the method of Barnea and Mizrahi. A user 
defined liquid phase inversion point is used in the 
calculation of the appropriate liquid phase viscosities (in 
other words, water-in-oil and oil-in-water). A residence 
time correction factor can also be applied. A droplet is 
carried over if the vertical distance travelled during its 
residence in the vessel is less than the vertical distance 
required to rejoin its bulk phase.
The Secondary Separation calculations for the gas phase 
are defined by a user-defined critical droplet size. The 
gas loading factor for each device is used to calculate the 
size of the exit device.
• ProSeparator4
The ProSeparator correlations are rigorous but are 
limited to calculating liquid carry over into gas. There are 
no calculations of liquid-liquid separation or gas 
entrainment in the liquid phases (they are set to zero). 
Light liquid and heavy liquid entrainments are calculated 
separately and the total carry over is the sum of the 
separate light and heavy liquid carry over calculations.
For Inlet Calculations, minimum and maximum droplet 
diameter are calculated based on inlet flow conditions 
(inlet gas flow rate and gas-liquid phase physical 
properties) and inlet pipe size. The droplet distribution of 
light and heavy liquids in the inlet gas is then calculated 
using a Rosin-Rammler type distribution.
The droplet d95 of the liquid-liquid dispersions (in other 
words, heavy liquid in light liquid and light liquid in heavy 
liquid) is not specified but calculated using the inlet droplet 
d95 and the densities of the 2 liquid phases.10-40
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ThPrimary Gas-Liquid Separation is based on critical droplet 
size; however, the critical droplet size is not user-
specified but calculated using gas velocity through the 
vessel.
Secondary Gas-Liquid Separation accomplished using 
exit devices (for example, demisting pad) are calculated 
by device specific correlations. The user can choose from 
vane pack or mesh pad devices. There are 2 different 
calculation methods available for each type of device.
Dimensions Setup
The Dimensions Setup group allows you to set the orientation, 
and the geometry of the vessel. You can also set the operating 
levels for the light and heavy liquid in the vessel. You have the 
option to model the horizontal vessel with weir or a boot by 
selecting the Has Weir checkbox and Has Boot checkbox, 
respectively.
ProSeparator effectively calculates its own Rossin Rammler 
parameters5 (droplet diameters) and does not require the 
user to specify these parameters. The only user input in the 
inlet calculations is the ability to limit the amount of phase 
dispersion calculated.
 Figure 10.2310-41
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ThDP/Nozzle Setup
The Pressure Drop/Nozzle Setup group allows you to model the 
method of DP (pressure drop), and the geometry of the nozzles. 
In the Pressure Drop table, after you have selected a DP method 
from the drop-down list, you can activate the Inlet Device DP 
Method, and the Vapour Exit DP Method by selecting the Active 
checkbox. You can click on the View Method button to view the 
parameters of the DP method you have selected.
 Figure 10.24
Since the dynamic pressure and the pressure drop of the 
feed stream and vessel are specified in the Specs page of the 
Dynamics tab, the Pressure Drop table is not available when 
the separator is operating in dynamics mode.10-42
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Separation Operations 10-43
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ThIn the Nozzle Diameter/Location table, you can set the diameter, 
height, and location for all the streams connected to the vessel.
If a Correlation Based carry over model is selected:
• the options on the DP / Nozzles Setup page can be 
used to calculate the inlet and exit nozzle pressure drop.
• the user-specified pressure drops on the Parameters 
page of the Design tab can be used instead.
C. Over Results Page
The C. Over Results page allows you to view the carry over 
results in the feed, and product streams based on what you 
specified in the C. Over Setup page. There are four columns of 
data in the Carry Over Results table:
• Frac. of Feed
• Frac. in Product
• Product Flow
• Prod. Mass/Vol 
The C. Over Results page information is also available in 
Dynamic mode.
 Figure 10.2510-43
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10-44 Separator, 3-Phase Separator, & 
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ThThe units for Frac. of Feed, and Prod. Mass/Vol are set by 
default. You can change the unit for the Frac. in Product and 
Product Flow column by selecting one of the four units from the 
Product Basis drop-down list (Mole, Mass, Liq. Volume, and 
Actual Volume).
You can view the carry over dispersion results by clicking on the 
View Dispersion Results button.
The Carry Over Dispersion Results property view has two tabs:
• Table. Displays the dispersion results for a single phase 
at a given point in the vessel. The radio buttons allow 
you to select the results of the corresponding phase. You 
can select the unit to be displayed from the Dispersion 
Basis drop-down list.
• Plot. Provides a graphically interpretation of the 
dispersed quantity against the droplet size for a single 
dispersion. The Select Plot checkboxes allow you to 
select one or more dispersions to be plotted. You can 
select the dispersion basis from the Dispersion Basis 
drop-down list.
 Figure 10.2610-44
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Th10.2.6 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
10.2.7 Dynamics Tab
Most of the options available on this tab is relevant only to cases 
in Dynamics mode. 
There is one exception, the Heat Exchanger Page allows you 
to specify whether or not the separator operation contains an 
energy stream used to heat or cool the vessel.
 Figure 10.27
The PF Specs page is relevant to dynamics cases only.
Refer to Section 1.3.10 - 
Worksheet Tab for more 
information.10-45
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10-46 Separator, 3-Phase Separator, & 
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ThSpecs Page
The Specs page contains information regarding initialization 
modes, vessel geometry, and vessel dynamic specifications.
Model Details
You can determine the composition and amount of each phase in 
the vessel holdup by specifying different initialization modes. 
HYSYS forces the simulation case to re-initialize whenever the 
initialization mode is changed. The radio buttons in the Model 
Details group are briefly described in the table below.
 Figure 10.28
Initialization Mode Description
Initialize from 
Products
The composition of the holdup is calculated from a 
weighted average of all products exiting the 
holdup. A PT flash is performed to determine other 
holdup conditions. The liquid level is set to the 
value indicated in the Liq Volume Percent field.10-46
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ThIn the Model Details group, you can specify the vessel geometry 
parameters:
• Vessel Volume
• Vessel Diameter
• Vessel Height (Length)
• Liq Volume Percent
You can modify the level in the vessel at any time. HYSYS 
then uses that level as an initial value when the 
integrator is run.
• Vessel Geometry (Level Calculator)
• Fraction Calculator
Fraction Calculator
The Fraction Calculator determines how the levels in the tank, 
and the elevation and diameter of the nozzles affect the product 
composition. The following is a description of the Fraction 
Calculator options:
• Use Levels and Nozzles. The nozzle location and vessel 
phase (liquid/vapour) level determines how much of each 
phase, inside the vessel, will exit through that nozzle. 
For example, if a vessel contained both liquid and vapour 
phases and the nozzle is below the liquid level, then 
Dry Startup The composition of the holdup is calculated from a 
weighted average of all feeds entering the holdup. 
A PT flash is performed to determine other holdup 
conditions. The liquid level in the Liq Volume 
Percent field is set to zero.
Initialize from User The composition of the liquid holdup in the vessel 
is user specified. The molar composition of the 
liquid holdup can be specified by clicking the Init 
Holdup button. The liquid level is set to the value 
indicated in the Liq Volume Percent field.
The vessel geometry parameters can be specified in the 
same manner as those specified in the Geometry group for 
the Sizing page of the Rating tab.
The Fraction Calculator defaults to the correct mode for all 
unit operations and does not typically require any changing.
Initialization Mode Description
For more information, see 
the section on Nozzles 
Page.10-47
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10-48 Separator, 3-Phase Separator, & 
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Thliquid will flow out through it. If the nozzle is above the 
liquid level, then vapour will flow out through it. 
• Emulsion Liquids. This behaves like the Use Levels and 
Nozzles option, except it simulates a mixer inside the 
vessel that mixes two liquid phases together so they do 
not separate out. 
For example, if a nozzle is below the lighter liquid level 
and the vessel has two liquid phases, the product is a 
mixture of both liquid phases.
Dynamic Specifications
The frictional pressure loss at the feed nozzle is a dynamic 
specification in HYSYS. It can be specified in the Feed Delta P 
field. The frictional pressure losses at each product nozzle are 
automatically set to zero by HYSYS.
If you want to model friction loss at the inlet and exit stream, it 
is suggested you add valve operations. In this case, flow into 
and out of the vessel is realistically modeled.
The vessel pressure can also be specified. This specification can 
be made active by selecting the checkbox beside the Vessel 
Pressure field. This specification is typically not set since the 
pressure of the vessel is usually a variable and determined from 
the surrounding pieces of equipment.
It is recommended that you enter a value of zero in the Feed 
Delta P field because a fixed pressure drop in the vessel is 
not realistic for all flows.10-48
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Separation Operations 10-49
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ThHoldup Page
The Holdup page contains information regarding the properties, 
composition, and amount of the holdup.
The Vessel Levels group displays the following variables for each 
of the phases available in the vessel:
• Level. Height location of the phase in the vessel.
• Percent Level. Percentage value location of the phase in 
the vessel.
• Volume. Amount of space occupied by the phase in the 
vessel.
Stripchart Page
The Stripchart page allows you to select a default strip chart 
containing various variable associated to the operation.
 Figure 10.29
Refer to Section 1.3.3 
- Holdup Page for 
more information.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.10-49
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10-50 Separator, 3-Phase Separator, & 
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ThHeat Exchanger Page
The Heat Exchanger page allows you to select whether the unit 
operation is heated, cooled, or left alone. You can also select the 
method used to heat or cool the unit operation. 
The options available in the Heat Exchanger page depends on 
which radio button you select:
• If you select the None radio button, this page is blank 
and you do not have to specify an energy stream in the 
Connections page (from the Design tab) for the 
separator operation to solve.
• If you select the Duty radio button, this page contains 
the standard heater or cooler parameters and you have 
to specify an energy stream in the Connections page 
(from the Design tab) for the separator operation to 
solve.
• If you select the Tube Bundle radio button, this page 
contains the parameters used to configure a heat 
exchanger and you have to specify material streams in 
the Connections page (from the Design tab) for the 
separator operation to solve.
 Figure 10.30
Refer to Duty Radio 
Button for more 
information.
Refer to Tube Bundle 
Radio Button for more 
information.10-50
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Separation Operations 10-51
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Th10.3 Shortcut Column
The Shortcut Column performs Fenske-Underwood short cut 
calculations for simple refluxed towers. The Fenske minimum 
number of trays and the Underwood minimum reflux are 
calculated. A specified reflux ratio can then be used to calculate 
the vapour and liquid traffic rates in the enriching and stripping 
sections, the condenser duty and reboiler duty, the number of 
ideal trays, and the optimal feed location. 
The Shortcut Column is only an estimate of the Column 
performance and is restricted to simple refluxed Columns. For 
more realistic results the rigorous Column operation should be 
used. This operation can provide initial estimates for most 
simple Columns.
10.3.1 Shortcut Column 
Property View
There are two ways that you can add a Shortcut Column to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Short Cut Columns radio button.
3. From the list of available unit operations, select the 
Shortcut Column model.
4. Click the Add button. 
The Tube Bundle options are only available in Dynamics 
mode and for Separator and Three Phase Separator.
If you switch from Duty option or Tube Bundle option to 
None option, HYSYS automatically disconnects the energy or 
material streams associated to the Duty or Tube Bundle 
options.10-51
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10-52 Shortcut Column
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ThOR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click the Short Cut Distillation icon. 
The Shortcut Column property view appears.
10.3.2 Design Tab
The Design tab contains the following pages: 
• Connections
• Parameters
• User Variables
• Notes
 Figure 10.31
Short Cut Distillation icon10-52
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ThConnections Page
You must specify the feed stream, overhead product, bottoms 
product, condenser, and reboiler duty name on the Connections 
page. 
The overhead product can either be an overhead vapour or a 
distillate stream, depending on the radio button selected in the 
Top Product Phase group. The operation name can also be 
changed on this page.
Parameters Page
The Shortcut Column requires the light key and heavy key 
components to be defined. The light key is the more volatile 
component of the two main components that are to be 
separated. The compositions of the keys are used to specify the 
distillation products.  
 Figure 10.32
You can specify the top product to be either liquid or vapour 
using the radio buttons in the Top Product Phase group.
The composition of the light key in the bottoms and the 
heavy key in the overhead are the only composition 
specifications required.10-53
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10-54 Shortcut Column
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ThIn the Components group, select the light key in bottoms and 
heavy key in distillation component from the drop-down list in 
the component cell, and specify their corresponding mole 
fraction. The specification must be such that there is enough of 
both keys to be distributed in the bottoms and overhead. It is 
possible to specify a large value for the light key composition 
such that too much of the light key is in the bottoms, and the 
overhead heavy key composition spec cannot be met. If this 
problem occurs, one or both of the key specs must be changed.
In the Pressures group, you can define the column pressure 
profile by specifying a value in the Condenser Pressure field and 
a Reboiler Pressure field.
In the Reflux Ratios group, the calculated minimum reflux ratio 
appears once streams are attached on the Connections page, 
and the required parameters are specified in the Components 
group and Pressures group.
You can then specify an external reflux ratio, which is used to 
calculate the tray traffic, the condenser and reboiler duties, the 
ideal number of trays, and the optimum tray location. The 
external reflux ratio must be greater than the minimum reflux 
ratio.
 Figure 10.3310-54
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Th10.3.3 Rating Tab
You currently cannot provide any rating information for the 
Shortcut Column.
10.3.4 Worksheet Tab
The Worksheet tab displays a summary of the information 
contained in the stream property view for all the streams 
attached to the operation.
10.3.5 Performance Tab
The Performance tab allows you to examine the results of the 
Shortcut Column calculations. The results correspond to the 
external reflux ratio value that you specified on the Parameters 
page.
The following results are available on the:
 Figure 10.34
Column Result Description
Minimum Number of 
Trays
The Fenske minimum number of trays, which is 
not affected by the external reflux ratio 
specification.
Actual Number of 
Trays
Calculated using a using the Gilliland method. 
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.10-55
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10-56 References
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Th10.3.6 Dynamics Tab
The Shortcut Column currently runs only in Steady State mode. 
As such, there is no information available on the Dynamics tab.
10.4 References
 1 GPSA, Vol 1, 10th Ed., January 1990.
 2 Separation Mechanism of Liquid-Liquid Dispersions in a deep-layer 
Gravity, Settler, E. Barnea and J Mizrahi, Trans. Instn. Chem. Engrs, 
1975, Vol 53.
 3 Droplet size spectra generated in turbulent pipe flow of dilute liquid-
liquid dispersions, A J Karabelas, AIChE, 1978, vol. 24, No. 2, pages 
170-181.
 4 Society of Petroleum Engineers papers: 
SPE36647 – Separator Design and Operation: Tools for Transferring 
"Best Practise"
SPE21506 – Proseparator – a novel separator/scrubber design 
program
 5 Aspen Process Manuals – Mini Manual 1: Gas & Particle Properties; 
Part 8 – Particle Size
 6 Aspen Process Manuals – Gas Cleaning Manual:
Vol 1 – Introduction
Vol 2 – Demisting
Vol 10 – Applied Technology
Optimal Feed Stage Top down feed stage for optimal separation.
Condenser and 
Reboiler Temperatures 
These temperatures are not affected by the 
external reflux ratio specification.
Rectifying Section 
Vapour and Liquid 
traffic flow rates
The estimated average flow rates above the 
feed location.
Stripping Section 
Vapour and Liquid 
traffic flow rates
The estimated average flow rates below the 
feed location.
Condenser and 
Reboiler Duties
The duties, as calculated by HYSYS.
Column Result Description10-56
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Solid Separation Operations 11-1
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Th11 Solid Separation 
Operationsw.cadfamily.com    EMa
e document is for study 11.1  Baghouse Filter............................................................................ 3
11.1.1  Baghouse Filter Property View .................................................. 3
11.1.2  Design Tab ............................................................................ 4
11.1.3  Rating Tab ............................................................................. 6
11.1.4  Worksheet Tab ....................................................................... 7
11.1.5  Performance Tab .................................................................... 7
11.1.6  Dynamics Tab ........................................................................ 8
11.2  Cyclone ........................................................................................ 8
11.2.1  Cyclone Property View............................................................. 8
11.2.2  Design Tab ............................................................................ 9
11.2.3  Rating tab ........................................................................... 12
11.2.4  Worksheet Tab ..................................................................... 15
11.2.5  Performance Tab .................................................................. 15
11.2.6  Dynamics Tab ...................................................................... 15
11.3  Hydrocyclone ............................................................................. 16
11.3.1  Hydrocyclone Property View................................................... 16
11.3.2  Design Tab .......................................................................... 17
11.3.3  Rating tab ........................................................................... 20
11.3.4  Worksheet Tab ..................................................................... 21
11.3.5  Performance Tab .................................................................. 22
11.3.6  Dynamics Tab ...................................................................... 22
11.4  Rotary Vacuum Filter ................................................................. 22
11.4.1  Rotary Vacuum Filter Property View ........................................ 23
11.4.2  Design Tab .......................................................................... 24
11.4.3  Rating tab ........................................................................... 26
11.4.4  Worksheet Tab ..................................................................... 28
11.4.5  Dynamics Tab ...................................................................... 2811-1
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11-2 Solid Separation Operations 
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The document is for study 11.5  Simple Solid Separator ...............................................................29
11.5.1  Simple Solid Separator Property View ......................................29
11.5.2  Design Tab ...........................................................................30
11.5.3  Rating Tab............................................................................33
11.5.4  Worksheet Tab ......................................................................33
11.5.5  Dynamics Tab .......................................................................3311-2
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Solid Separation Operations 11-3
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Th11.1 Baghouse Filter
The Baghouse Filter model is based on empirical equations. It 
contains an internal curve relating separation efficiency to 
particle size. Based on your particle diameter, the reported 
separation efficiency for your solids is determined from this 
curve. The solids being separated must be previously specified 
and installed as components in the stream attached to this 
operation.
11.1.1 Baghouse Filter 
Property View
There are two ways that you can add a Baghouse Filter to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Solids Handling radio button.
3. From the list of available unit operations, select Baghouse 
Filter.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.11-3
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11-4 Baghouse Filter
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Th2. Click on the Solid Ops icon. The Solid Operations Palette 
appears.
3. Double-click the Baghouse Filter icon. 
The Baghouse Filter property view appears.
11.1.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 11.1
 Figure 11.2
Solid Ops icon
Baghouse Filter icon11-4
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ThConnections Page
On the Connections page, you can specify the name of the 
operation, as well as the feed, vapour product, and solid product 
streams.
Parameters Page
On the Parameters page, you must specify the following 
information:  
 Figure 11.3
 Figure 11.4
Parameter Description
Configuration When you make a change to any of the parameters, 
the configuration changes to User Defined. Select 
Default to revert to the HYSYS defaults.11-5
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11-6 Baghouse Filter
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
11.1.3 Rating Tab
The Rating tab consists of the Sizing page.
Sizing Page
On the Sizing page, the following parameters can be specified: 
Clean Bag 
Pressure Drop
The pressure drop across a clean bag.
Dirty Bag 
Pressure Drop
The pressure drop across a dirty bag. This value must 
be greater than the Clean Bag Pressure Drop.
 Figure 11.5
Parameter Description
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.11-6
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Solid Separation Operations 11-7
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Th11.1.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
11.1.5 Performance Tab
The Performance tab consists of the Results page.
Results page
The following Filtration results appear on this page:
• Filtration Time
• Number of Cells
• Area/Cell
• Total Cell Area
• Particle Diameter
Parameter Description
Maximum Gas 
Velocity
Maximum velocity of gas in the Baghouse Filter.
Bag Filter Area Filter Area for each bag.
Bag Diameter Bag Diameter.
Bags per Cell Number of bags per filter cell.
Bag Spacing Spacing between the bags.
 Figure 11.6
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.11-7
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11-8 Cyclone
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Th11.1.6 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
11.2 Cyclone
The Cyclone is used to separate solids from a gas stream and is 
recommended only for particle sizes greater than 5 microns. The 
Cyclone consists of a vertical cylinder with a conical bottom, a 
rectangular inlet near the top, and an outlet for solids at the 
bottom of the cone. It is the centrifugal force developed in the 
vortex which moves the particles toward the wall. Particles 
which reach the wall, slide down the cone, and so become 
separated from the gas stream. The solids being separated must 
be previously specified and installed as components in the 
stream attached to this operation.
11.2.1 Cyclone Property View
There are two ways that you can add a Cyclone to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Solids Handling radio button.
3. From the list of available unit operations, select Cyclone.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.11-8
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Th2. Click on the Solid Ops icon. The Solid Operations Palette 
appears.
3. Double-click the Cyclone icon. 
The Cyclone property view appears.
11.2.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Solids
• User Variables
• Notes
 Figure 11.7
 Figure 11.8
Solid Ops icon
Cyclone icon11-9
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11-10 Cyclone
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ThConnections Page
You can specify the name of the operation, as well as the feed, 
vapour product, and solid product streams on the Connections 
page.
Parameters Page 
On the Parameters page, you can specify the following 
parameters:      
 Figure 11.9
 Figure 11.1011-10
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ThThe diameter provided, either from the selected component or 
from the particle characteristics, is used in the efficiency 
calculations. For example, if you select an 85% efficiency, 85% 
of the solids of the specified diameter is recovered. All other 
solids in the inlet stream are removed at an efficiency related to 
these parameters.
Solids Page
You can specify the solid characteristics on the Solids page. This 
page contains two different data, depending on the radio button 
you selected in the Efficiency Basis group.
Parameter Description
Configuration Select either High Efficiency, High Output or User 
Defined.
Efficiency 
Method
Select either the Lapple or the Leith/Licht method. The 
latter is a more rigorous calculation as it considers 
radial mixing effects.
Particle 
Efficiency
The percent recovery of the specified solid in the 
bottoms stream.
 Figure 11.1111-11
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11-12 Cyclone
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ThWhen you select the Single Particle Diameter radio button, the 
following solids information can be specified: 
When you select the Particle Size Distribution radio button, the 
following solids information can be specified: 
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
11.2.3 Rating tab
The Rating tab contains the following pages:
• Sizing 
• Constraints
Parameter Description
Solid Name You must provide either the name of a solid 
already installed in the case, or provide a particle 
diameter and density.
Particle Diameter and 
Particle Density
If you do not choose a solid component, provide 
the particle diameter and density.
Parameter Description
Solid Name You must provide either the name of a solid 
already installed in the case, or provide a particle 
diameter and density.
Particle Density If you do not choose a solid component, provide 
the particle density.
Particle Size 
Distribution
If you do not choose a solid component, provide 
the minimum or maximum particle size.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.11-12
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Solid Separation Operations 11-13
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ThSizing Page
The Sizing page contains two groups:
• Design Mode. Contains two radio buttons: On and Off. 
The radio buttons enables you to toggle between turning 
on or turning off the Design Mode option.
When you select the Off radio button, the Specify 
Number of Parallel Cyclones checkbox appears in the 
Sizing page. Select the checkbox if you want to specify 
the number of parallel Cyclones in the flowsheet.
• Sizing Ratios. Contains a table. 
The table below describes the parameters available on 
the page:
 Figure 11.12
Parameter Description
Configuration Select High Output, High Efficiency, or User Defined. 
This is also defined on the Parameters page.
Inlet Width Ratio The ratio of the inlet width to the body diameter (must 
be between 0 and 1).
The value must be less than the Total Height Ratio
Inlet Height 
Ratio
The ratio of the inlet height to the body diameter.
Cyclone Height 
Ratio
The ratio of the Cyclone height to the body diameter. 
The Cyclone is the conical section at the bottom of the 
entire operation.
Gas Outlet 
Length Ratio
The ratio of the gas outlet length to the body diameter.
Gas Outlet 
Diameter Ratio
The ratio of the gas outlet diameter to the body 
diameter (must be between 0 and 1).
The value must be less than the Total Height Ratio11-13
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11-14 Cyclone
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ThConstraints Page
On the Constraints page, you can specify the minimum and 
maximum diameter for the Cyclone. The page is also applicable 
only when the On radio button is selected in the Design Mode 
group.
The Maximum Pressure Drop and Maximum Number of Cyclones 
is set on this page. These are used in the calculations to 
determine the minimum number of Cyclones needed to 
complete the separation. 
Total Height 
Ratio
The ratio of the total height of the apparatus to the 
body diameter.
Solids Outlet 
Diameter Ratio
The ratio of the solids outlet diameter to the body 
diameter.
Body Diameter If Design Mode is on, this is automatically calculated, 
within the provided constraints. If Design Mode is off, 
then you can specify this value.
# Parallel 
Cyclones
If Design Mode is on, this field displays the number of 
parallel Cyclones (if any) attached to the unit 
operation. If Design Mode is off and the Specify 
Number of Parallel Cyclones checkbox is selected, 
you can specify this value.
 Figure 11.13
Parameter Description11-14
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Solid Separation Operations 11-15
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Th11.2.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation.
11.2.5 Performance Tab
The Performance tab contains the Results page.
Results Page
The Results page displays the calculated pressure drop, overall 
efficiency, and the number of parallel Cyclones.
11.2.6 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
 Figure 11.14
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.11-15
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11-16 Hydrocyclone
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Th11.3 Hydrocyclone
The Hydrocyclone is essentially the same as the cyclone, the 
primary difference being that this operation separates the solid 
from a liquid phase, rather than a gas phase. The solids being 
separated must be previously specified and installed as 
components in the stream attached to this operation.
11.3.1 Hydrocyclone Property 
View
There are two ways that you can add a Hydrocyclone to your 
simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitsOps property view by pressing 
F12.
2. Click the Solids Handling radio button.
3. From the list of available unit operations, select 
Hydrocyclone.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.11-16
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Solid Separation Operations 11-17
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Th2. Click on the Solid Ops icon. The Solid Operations Palette 
appears.
3. Double-click the Hydrocyclone icon. 
The Hydrocyclone property view appears.
11.3.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Solids
• User Variables
• Notes
 Figure 11.15
 Figure 11.16
Solid Ops icon
Hydrocyclone icon11-17
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11-18 Hydrocyclone
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ThConnections Page
On the Connections page, you can specify the name of the 
operation, as well as the feed, liquid product, and solid product 
streams.
Parameters Page
On the Parameters page, you can specify the following 
parameters: 
 Figure 11.17
Parameter Description
Configuration Select either Mode 1, Mode 2 or User Defined.
Particle 
Efficiency
The percent recovery of the specified solid in the 
bottoms stream.
 Figure 11.1811-18
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Solid Separation Operations 11-19
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ThThe diameter provided, either from the selected component or 
from the particle characteristics, is used in the efficiency 
calculations. For example, if you select an 85% efficiency, 85% 
of the solids of the specified diameter are recovered. All other 
solids in the inlet stream are removed at an efficiency related to 
these parameters.
Solids Page
On the Solids page, the following solids information can be 
specified:  
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
Parameter Description
Solid Name You must provide either the name of a solid already installed in the 
case, or provide a particle diameter and density. 
Particle Diameter 
and Particle Density
If you do not specify a Solid Name, provide the particle diameter and 
density.
 Figure 11.19
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.11-19
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11-20 Hydrocyclone
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Th11.3.3 Rating tab
The Rating tab contains the following pages:
• Sizing
• Constraints
Sizing Page
The Sizing page contains two groups:
• Design Mode. Contains two radio buttons: On and Off.
The radio buttons enable you to toggle between turning 
on or turning off the Design Mode option.
• Sizing Ratio. Contains a table.
The table below describes the parameters available on 
the page:
 Figure 11.20
Parameter Description
Configuration Select Mode 1, Mode 2 or User Defined. This is also 
defined on the Parameters page.
Inlet Diameter 
Ratio
The ratio of the inlet diameter to the body diameter.
Included Angle 
(Degrees)
The angle of the cyclone slope to the vertical.
Overflow Length 
Ratio
The ratio of the overflow length to the body diameter.
Overflow 
Diameter Ratio
The ratio of the overflow diameter to the body 
diameter.
Total Height 
Ratio
The ratio of the total height of the apparatus to the 
body diameter.11-20
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ThConstraints Page
You can specify the minimum and maximum diameter for the 
Cyclone, applicable only when the On radio button is selected in 
the Design Mode group.
The Maximum Pressure Drop and Maximum Number of Cyclones 
can also be set on this page.
11.3.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
Underflow 
Diameter Ratio
The ratio of the underflow diameter to the body 
diameter.
Body Diameter If Design Mode is on, then this is automatically 
calculated, within the provided constraints. If Design 
Mode is off, then you can specify this value.
 Figure 11.21
Parameter Description
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.11-21
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11-22 Rotary Vacuum Filter
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Th11.3.5 Performance Tab
The Performance tab consists of the Results page.
Results Page
The calculated pressure drop, overall efficiency, and the number 
of parallel cyclones appear on this page.
11.3.6 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
11.4 Rotary Vacuum Filter
The Rotary Vacuum Filter assumes that there is 100% removal 
of the solid from the solvent stream. This operation determines 
the retention of solvent in the particle cake, based on the 
particle diameter and sphericity of your defined solid(s). The 
diameter and sphericity determines the capillary space in the 
cake and thus the solvent retention. The solids being separated 
must be previously specified and installed as components in the 
stream attached to this operation.
 Figure 11.2211-22
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Solid Separation Operations 11-23
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Th11.4.1 Rotary Vacuum Filter 
Property View
There are two ways that you can add a Rotary Vacuum Filter to 
your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Solids Handling radio button.
3. From the list of available unit operations, select Rotary 
Vacuum Filter.
4. Click the Add button. 
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Click on the Solid Ops icon. The Solid Operations Palette 
appears.
3. Double-click the Rotary Vacuum Filter icon. 
 Figure 11.23
Solid Ops icon
Rotary Vacuum Filter 
icon11-23
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11-24 Rotary Vacuum Filter
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ThThe Rotary Vacuum Filter property view appears.
11.4.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• User Variables
• Notes
 Figure 11.2411-24
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ThConnections Page
On the Connections page, you can define the operation name, 
as well as the feed, liquid product, and solids product streams.
Parameters Page
The Rotary Vacuum Filter parameters are described in the table 
below:   
 Figure 11.25
 Figure 11.26
Parameter Description
Cycle Time The complete time for a cycle (one complete revolution 
of the cylinder).
Dewatering The portion of the cycle between the time the cake 
comes out of the liquid to the time it is scraped, 
expressed as a percentage of the overall cycle time.11-25
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11-26 Rotary Vacuum Filter
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation. 
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
11.4.3 Rating tab
The Rating tab contains the following pages:
• Sizing 
• Cake
Sizing Page 
You can specify the following filter size parameters:  
Submergence The percentage of the overall cycle for which the cake 
is submerged.
Pressure Drop Pressure drop across the filter.
Parameter Description
Filter Radius The radius of the filter. This defines the circumference of 
the drum.
Filter Width The horizontal filter dimension.
Filter Area The area of the filter.
Parameter Description
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.11-26
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Solid Separation Operations 11-27
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ThCake Page
The Cake page consists of two groups:
• Cake Properties
• Resistance
You can define the cake properties in the Cake Properties group.
 Figure 11.27
 Figure 11.28
Property Description
Mass Fraction of 
Cake
The final solid mass fraction.
Thickness The thickness of the cake.
Porosity The overall void space in the cake.11-27
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11-28 Rotary Vacuum Filter
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ThYou can define the resistance or use a resistance equation in the 
Resistance group. Selecting the Use Resistance Equation 
checkbox, which allows HYSYS to calculate the resistance value 
based on the Filtration Resistance equation.
The Filtration Resistance equation is as follows:
where:  
a, s = constants
dP = pressure drop
11.4.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
11.4.5 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
Irreducible 
Saturation
The solvent retention at infinite pressure drop.
Permeability If you do not provide a value, HYSYS calculates this 
from the sphericity and diameter of the solid.
Resistance = a(dP)s (11.1)
Property Description
Refer to Section 1.3.10 
- Worksheet Tab for 
more information.11-28
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Th11.5 Simple Solid 
Separator
The Simple Solid Separator (Simple Filter) performs a non-
equilibrium separation of a stream containing solids. This 
operation does not perform an energy balance, as the 
separation is based on your specified carry over of solids in the 
vapour and liquid streams, and liquid content in the solid 
product. It should be used when you have an existing operation 
with known carry over or entrainment in the product streams. 
The solids being separated must be previously specified and 
installed as components in the stream attached to this 
operation.
11.5.1 Simple Solid Separator 
Property View
There are two ways that you can add a Simple Solid Separator 
to your simulation:
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Solids Handling radio button.
3. From the list of available unit operations, select Simple 
Solid Separator.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.11-29
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11-30 Simple Solid Separator
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Th2. Click on the Solid Ops icon. The Solid Operations Palette 
appears.
3. Double-click the Simple Solid Separator icon. 
The Simple Solid Separator property view appears.
11.5.2 Design Tab
The Design tab contains the following pages:
• Connections
• Parameters
• Splits
• User Variables
• Notes
 Figure 11.29
 Figure 11.30
Solid Ops icon
Simple Solid Separator 
icon11-30
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ThConnections Page
You can specify the name of the operation, feed stream, and 
product streams (Vapour, Liquid, Solids) on the Connections 
page.
Parameters Page
You can specify the pressure drop on the Parameters page.
 Figure 11.31
 Figure 11.3211-31
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11-32 Simple Solid Separator
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ThSplits Page 
On the Splits page, you must choose the split method by 
defining a Type of Fraction. 
The types of fraction are described in the table below.   
In the flowsheet, the streams are not reported as single phase, 
due to the solid content in the vapour and liquid streams, and 
the liquid content in the solid product stream.
User Variables Page
The User Variables page enables you to create and implement 
your own user variables for the current operation.
 Figure 11.33
Object Definition
Split 
Fractions
Specify the fractional distribution of solids from the feed 
into the vapour and liquid product streams. The solids 
fraction in the bottoms are calculated by HYSYS. You must 
also specify the fraction of liquid in the bottoms (solid 
product).
Stream 
Fractions
Enter the mole, mass or liquid volume fraction specification 
for each of the following:
• Total vapour product solids fraction on the specified 
basis.
• Total liquid product solids fraction on the specified 
basis.
• Liquid phase fraction in the bottom product.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.11-32
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ThNotes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the specific unit operation, 
or your simulation case in general.
11.5.3 Rating Tab
This unit operation currently does not have rating features.
11.5.4 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation.
11.5.5 Dynamics Tab
This unit operation is currently not available for dynamic 
simulation.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.
 Refer to Section 
1.3.10 - Worksheet 
Tab for more 
information.11-33
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11-34 Simple Solid Separator
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Th11-34
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Streams 12-1
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Th12 Streams12-1
12.1  Energy Stream Property View ...................................................... 2
12.1.1  Stream Tab............................................................................ 3
12.1.2  Unit Ops Tab .......................................................................... 3
12.1.3  Dynamics Tab ........................................................................ 4
12.1.4  Stripchart Tab ........................................................................ 4
12.1.5  User Variables Tab .................................................................. 4
12.2  Material Stream Property View .................................................... 5
12.2.1  Worksheet Tab ....................................................................... 8
12.2.2  Attachments Tab .................................................................. 30
12.2.3  Dynamics Tab ...................................................................... 33
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Th12.1 Energy Stream 
Property View
Energy streams are used to simulate the energy travelling in 
and out of the simulation boundaries and passing between unit 
operations.
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing the F4 hot 
key.
2. Double-click the Energy Stream icon. 
The Energy Stream property view appears.
The Energy Stream property view contains the following tabs 
that allow you to define stream parameters, view objects to 
which the stream is attached, and specify dynamic information:
• Streams
• Unit Ops
• Dynamics
• Stripchart
• User Variables
As with the material streams, the energy stream property view 
has the View Upstream Operation icon and the View 
Downstream Operation icon that allow you to view the unit 
operation to which the stream is connected. Energy streams 
 Figure 12.1
Energy Stream icon
View Upstream 
Operation icon
View Downstream 
Operation icon12-2
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Streams 12-3
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Thdiffer from material streams in that if there is no upstream or 
downstream connection on the stream (which is often the case 
for the energy stream) the associated icon is not active.
12.1.1 Stream Tab
The Stream tab allows you to specify the Stream Name and 
Heat Flow for the stream. The figure below shows the Stream 
tab of the Energy Stream property view. 
12.1.2 Unit Ops Tab
The Unit Ops tab displays the Names and Types of all objects to 
which the energy stream is attached. 
Both unit operations and logicals are listed. The Unit Ops tab 
either shows a unit operation in the Product From cell or in the 
 Figure 12.2
When converting an energy stream to a material stream, all 
material stream properties are unspecified, except for the 
stream name.
 Figure 12.312-3
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12-4 Energy Stream Property View
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ThFeed To cell, depending on whether the energy stream receives 
or provides energy respectively.
12.1.3 Dynamics Tab
The options on the Dynamics tab allow you to set the dynamic 
specifications for a simulation in dynamic mode. 
In dynamic mode, two different heating methods can be chosen 
for an energy stream. When the Direct Q radio button is 
selected, you can specify a duty value. When the Utility Fluid 
radio button is selected, the duty is calculated from specified 
properties of a utility fluid.
The Utility Valve button opens the Flow Control Valve (FCV) view 
for the energy stream. 
12.1.4 Stripchart Tab
The Stripchart tab currently does not have any functions.
12.1.5 User Variables Tab
The User Variables tab enables you to create and implement 
your own user variables for all energy streams.
You can double-click on either the Product From or Feed To 
cell to access the property view of the operation attached to 
the stream.
 Figure 12.4
For a detailed description 
of the Direct Q and Utility 
Fluid Heating methods, 
refer to Section 6.7 - 
Valve.
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.12-4
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Th12.2 Material Stream 
Property View
Material streams are used to simulate the material travelling in 
and out of the simulation boundaries and passing between unit 
operations. For the material stream you must define their 
properties and composition so HYSYS can solve the stream.
There are three methods to add a Material stream:
1. Select Flowsheet | Add Stream command from the menu 
bar.
OR
1. Pres the F11 hot key.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing the F4 hot 
key.
2. Double-click the Material Stream icon. 
Material Stream icon12-5
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12-6 Material Stream Property View
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ThThe Material Stream property view appears.
The Material Stream property view contains three tabs and 
associated pages that allow you to define parameters, view 
properties, add utilities, and specify dynamic information.
If you want to copy properties or compositions from existing 
streams within the flowsheet, click the Define from Other 
Stream button. The Spec Stream As Property View appears, 
which allows you to select the stream properties and/or 
compositions you want to copy to your stream.
The left green arrow is the View Upstream Operation icon, 
which indicates the upstream position. The right green arrow is 
the View Downstream Operation icon, which indicates the 
downstream position. If the stream you want is attached to an 
operation, clicking these icons opens the property view of the 
nearest upstream or downstream operation. If the stream is not 
connected to an operation at the upstream or downstream end, 
then these icons open a Feeder Block or a Product Block.
 Figure 12.5
View Upstream 
Operation icon
View Downstream 
Operation icon12-6
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ThSpec Stream As Property View
The Spec Stream As property view enables you to select 
properties/information from other streams and use that 
information to define a stream.
• The Available Streams list enables you to select the 
stream containing the properties you want to copy. You 
can only select one stream.
• In defining the basic stream properties, you can only 
select the checkboxes of two of the following stream 
properties for the new stream: vapour fraction, 
temperature, pressure, molar enthalpy, or molar entropy.
• The Composition checkbox enables you to copy the 
composition fraction values of the selected stream into 
the new stream.
• The Correlations checkbox enables you to copy the 
selected stream’s correlation configuration into the new 
stream.
• The Flow checkbox enables you to copy the selected 
stream’s flow rate value into the new stream. You can 
select the flow rate basis you want to copy into the new 
stream by selecting the appropriate radio button on the 
Flow Basis group.
• The Cost Parameters checkbox enables you to copy the 
cost parameters values of the selected stream into the 
new stream.
 Figure 12.612-7
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12-8 Material Stream Property View
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Th• The Cancel button enables you to exit the property view 
without accepting any changes.
• The OK button enables you to exit the property view and 
accepts any changes made.
12.2.1 Worksheet Tab
The Worksheet tab has pages that display information relating 
to the stream properties: 
• Conditions
• Properties
• Compositions
• K Value
• Electrolytes
• User Variables
• Notes
The figure below shows the Worksheet tab of a solved material 
stream within a simulation.
The Electrolytes page is only available if the stream is in an 
electrolyte system.
 Figure 12.7
The green 
status bar 
containing 
OK indicates 
a completely 
solved 
stream.12-8
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ThConditions Page
The Conditions page displays all of the default stream 
information as it is shown on the Material Streams tab of the 
Workbook property view. The names and current values for the 
following parameters appear below:
• Stream Name
• Vapour/Phase Fraction
• Temperature
• Pressure
• Molar Flow
• Mass Flow
• Std Ideal LiqVol Flow
• Molar Enthalpy
• Molar Entropy
• Heat Flow
• LiqVol Flow @ Std Cond
• Fluid Package
HYSYS uses degrees of freedom in combination with built-in 
intelligence to automatically perform flash calculations. In order 
for a stream to “flash”, the following information must be 
specified, either from your specifications or as a result of other 
flowsheet calculations:
• Stream Composition
Two of the following properties must also be specified; at least 
one of the specifications must be temperature or pressure:
• Temperature
• Pressure
• Vapour Fraction
In the electrolyte system, the Conditions page contains an 
extra column. This column displays the property parameters 
of the stream after electrolyte flash calculations.
At least one of the temperature or pressure properties must 
be specified for the material stream to solve.12-9
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12-10 Material Stream Property View
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Th• Entropy
• Enthalpy     
Depending on which of the state variables are known, HYSYS 
automatically performs the correct flash calculation.
Once a stream has flashed, all other properties about the 
stream are calculated as well. You can examine these properties 
through the additional pages of the property view. A flowrate is 
required to calculate the Heat Flow.
The stream parameters can be specified on the Conditions page 
or in the Workbook property view. Changes in one area are 
reflected throughout the flowsheet.
While the Workbook displays the bulk conditions of the stream, 
the Conditions page, Properties page, and Compositions page 
also show the values for the individual phase conditions. HYSYS 
can display up to five different phases.
• Overall 
• Vapour 
• Liquid. If there is only one hydrocarbon liquid phase, 
that phase is referred to as liquid.
• Liquid 1. This phase refers to the lighter liquid phase.
• Liquid 2. This phase refers to the heavier liquid phase.
In the electrolyte system, the entropy (S) is always a 
calculated property.
If you specify a vapour fraction of 0 or 1, the stream is 
assumed to be at the bubble point or dew point, respectively. 
You can also specify vapour fractions between 0 and 1.
For an electrolyte material stream, HYSYS conducts a 
simultaneous phase and reaction equilibrium flash on the 
stream.
For the reactions 
involved in the flash and 
the model used for the 
flash calculation, refer to 
Section 1.6.9 - 
Electrolyte Stream 
Flash in the HYSYS OLI 
Interface Reference 
Guide.12-10
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Th• Aqueous. In the absence of an aqueous phase, the 
heavier hydrocarbon liquid is treated as aqueous. When 
there is only one aqueous phase, that phase is labelled 
as aqueous.
• Mixed Liquid. This phase combines the Liquid phases of 
all components in a specified stream, and calculates all 
liquid phase properties for the resulting fluid. 
For example, if you expand the width of the default material 
stream property view (as shown in the figure below), you can 
view the hidden phase properties.
In HYSYS, the liquid phase, and aqueous phase are internally 
recognized as Liquid 1, and Liquid 2, respectively. Liquid 1 
refers to the lighter phase whereas the heavier phase is 
recognized as Liquid 2.
If there is only one hydrocarbon liquid phase, that phase is 
referred to as liquid. 
The Mixed Liquid phase does not add its composition or 
molar flow to the stream it is derived from. This phase is only 
another representation of existing liquid components.
 Figure 12.812-11
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12-12 Material Stream Property View
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ThIn this case, the vapour phase and liquid phase properties 
appear beside the overall stream properties. If there were 
another liquid phase, it would appear as well.
Dynamic Mode
In Dynamic mode, the Manipulate Conditions button appears on 
the Conditions page of the Material Stream property view. 
The Manipulate Conditions button allows you to change the 
values in a stream if you want to provide a different set of 
values for when the integrator is started. Normally, you would 
not have to use this feature. The Manipulate Conditions button is 
an advanced troubleshooting feature that you can use when you 
encounter problems, and you want to change the stream values 
temporarily to affect a downstream operation. You can use this 
feature, for example, if you ran the simulation and you got 
really cold temperatures out of a heat exchanger that is causing 
problems downstream. 
If you click the Manipulate Conditions button, the stream 
values in the table appear in red. You can then enter in a new 
temperature (even if the stream had no specifications before). 
The Manipulate Conditions button is also replaced by the 
Accept Stream Conditions button.
Rather than expanding the property view, you can use the 
horizontal scroll bar to view the hidden phase properties.
When you are viewing a stream property view in the column 
subflowsheet, there is an additional Create Column Stream 
Spec button on the Conditions page. 
This feature can be used on streams that feed into the 
flowsheet (sits on the boundary) and those that connect 
operations together. If the stream being changed flows out 
of a unit operation, its contents are likely overwritten by the 
upstream operation as soon as you start the integrator.
If the downstream operation is new or had problems solving, 
changing its feed stream may allow HYSYS to solve the 
downstream operation or initialize and solve a replacement 
unit operation.
For more information on 
the functionality of the 
Create Column Stream 
Spec button, refer to 
Section 2.6 - Column 
Stream Specifications.12-12
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Streams 12-13
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ThIf you click the Accept Stream Conditions button, HYSYS 
performs flash calculations again with the initial values you 
provided. The stream values in the table appear in black as 
before.
Properties Page
The Properties page displays the properties for each stream 
phase. The options in the Property Correlation Controls group 
enables you to manipulate the property correlations displayed 
on this page for an individual stream. By default the properties 
from the Conditions page are not available on this page.
The Properties page contains a table, a Preference Option 
display field, and a group of icons. 
• The table displays the property correlations you select for 
the stream. 
• The Preference Option display field is Active if the 
Activate Property Correlations checkbox is selected. 
This checkbox can be found on the Options page, 
Simulation tab of the Session Preferences property view. 
You can also manipulate the property correlations displayed 
in the Properties page using the Correlation Manager.
 Figure 12.9
Refer to Section 11.18 
- Correlation Manager 
in the HYSYS User 
Guide for more 
information.12-13
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12-14 Material Stream Property View
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Th• The Property Correlation Controls group contains ten 
icons. These icons are used to manipulate the property 
correlations displayed in the table. 
You can modify and over-write any existing correlation set 
using the stream’s Property Correlation Controls.
Name Icon Description
View Correlation Set 
List
Allows you to select a correlation set. 
Append New 
Correlation
Allows you to add a property correlation 
to the end of the table. 
Move Selected 
Correlation Down
Allows you to move the selected 
property correlation one row down the 
table.
Move Selected 
Correlation Up
Allows you to move the selected 
property correlation one row up the 
table.
Sort Ascending Allows you to sort the property 
correlations in the table by ascending 
alphabetic order.
Remove Selected 
Correlation
Allows you to remove the selected 
property correlation from the table. 
Remove All 
Correlations
Allows you to remove all the property 
correlations from the table.
Save Correlation Set 
to File
Allows you to save a set of property 
correlations. 
View Selected 
Correlation
Allows you to view the parameters and 
status of the selected property 
correlation. 
View All Correlation 
Plots
Allows you to view all correlation plots 
for the selected stream. 
Refer to Displaying a 
Correlation Set section 
for more information.
Refer to Adding a 
Property Correlation 
section for more 
information.
Refer to Removing a 
Property Correlation 
from the table section 
for more information.
Refer to Creating a 
Correlation Set section 
for more information. 
Refer to Viewing a 
Property Correlation 
section for more 
information.
Refer to Viewing All 
Correlation Plots 
section for more 
information.12-14
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Streams 12-15
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ThAdding a Property Correlation
To add a property correlation to the table:
1. Click the Append New Correlation icon. 
The Correlation Picker property view appears. 
2. Select a property correlation that you want to view from the 
branch list. Click the Plus icon  to expand the available 
correlations list.
3. Click the Apply button to append the selected property 
correlation to the stream. 
If the selected correlation cannot be calculated by that 
stream’s fluid, a message will be sent to the trace window 
informing the user that this property correlation cannot be 
added to the stream.
4. Repeat steps #2 to #3 to add another property correlation.
5. When you have completed appending property correlations 
to the stream, click the Close button to return to the stream 
property view.
To select a different stream to append the property correlations 
to:
1. Click the Select Material Stream to Append icon. The 
Select Material Stream property view appears.
2. Select the appropriate stream from the object list.
 Figure 12.10
Append New Correlation 
icon
HYSYS property 
correlations have 
been grouped 
into categories 
which target the 
specific reporting 
needs of the 
various process 
industries.
This display 
field shows the 
name of the 
stream the 
property 
correlation will 
be appended 
to.
Select Material Stream 
to Append icon12-15
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12-16 Material Stream Property View
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Th3. Click the OK button to return to the Correlation Picker 
property view. You can now add a property correlation to the 
selected stream.
The new selected stream’s name also appears in the display 
field located beside the Select Material Stream to Append 
icon.
Removing a Property Correlation from the 
table
To remove property correlations from the table:
1. Select the property correlation you want to remove in the 
table.
2. Click the Remove Selected Correlation icon. HYSYS 
removes the selected property correlation from the table.
You can remove all property correlations in the table by clicking 
the Remove All Correlations icon.
Creating a Correlation Set
To save the property correlations in the table as a set:
1. Add all the property correlations you want to the table.
2. Click the Save Correlation Set to File icon. The Save 
Correlation Set Name property view appears.
HYSYS automatically enters a name for the property list 
based on the stream name.
3. Enter the name you want for the property list in the Set 
Name (Global) field. Each correlation set name must be 
unique.
 Figure 12.11
Remove Selected 
Correlation icon
Remove All Correlations 
icon
Save Correlation Set to 
File icon
For example, the stream called 
AGO, HYSYS automatically enters 
the default name AGO-
CorrelationSet for the property list.12-16
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Streams 12-17
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Th4. Click the Save button to save the property list.
The saved correlation set can then be added to other streams 
using the View Correlation Set List icon displayed in each 
stream property view. You can also add the saved correlation set 
to all of the streams within the case by using the Correlation 
Manager.
Displaying a Correlation Set
To display a correlation set:
1. Click the View Correlation Set List icon. 
2. The Correlation Set Picker property view appears. 
3. Select the correlation set you want from the property view. 
If you are creating a correlation set for the first time, you are 
also creating the default file (Support\StreamCorrSets.xml) 
which will hold all these sets. You can change the name of 
the file on the Locations page, Files tab of the Session 
Preferences property view.
 Figure 12.12
If the xml file does not exist (you have never created a 
correlation set before) the window will display “File has not 
been created.” If the xml file does exist but all previous sets 
have been deleted, the window will display “File is empty.”
View Correlation Set List 
icon
View Correlation Set List 
icon
The location and name of the file 
that contains the correlation set is 
shown in the File Path field. The 
xml path and file name can be 
changed using the Session 
Preferences property view. 
Refer to Section 12.5.2 - 
Locations Page from the HYSYS 
User Guide.12-17
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12-18 Material Stream Property View
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ThTo see the list of correlations contained within the correlation 
set, click the associate Plue icon .
4. Click the Apply button. The Correlation Set Picker property 
view will close, and the property correlations contained in 
the selected correlation set will appear in that streams 
properties table.
5. Repeat steps #1 to #4 to apply additional correlation sets to 
your stream.
You can expand the property view or use the scroll bar to view 
any property correlation phase values, as shown in the figure 
below.
HYSYS will check each correlation’s type against the fluid 
type of the stream. If a problem occur while appending a 
correlation from the set, a warning will be sent to the Trace 
window.
 Figure 12.13
Refer to Section 1.3 - 
Object Status & Trace 
Windows in the HYSYS 
User Guide, for more 
information on Trace 
window.12-18
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Streams 12-19
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ThDeleting a Correlation Set
To delete a correlation set:
1. Click the View Correlation Set List icon.
2. The Correlation Set Picker property view appears.
3. Select the correlation set you want to delete.
4. Click the Delete button. A window will appear asking you if 
you are sure you want to delete the set because it cannot be 
undone.
5. Click the Yes button and the Correlation Set Picker property 
view appears with the chosen set deleted from the list.
6. Click the Close icon  to close the Correlation Set Picker 
property view and return to the stream property view.
 Figure 12.14
View Correlation Set List 
icon12-19
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12-20 Material Stream Property View
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ThViewing a Property Correlation
When you select a property correlation from the table and click 
the View Selected Correlation icon, the following property 
view appears.
The following table describes the status bars contained in the 
Status group.
 Figure 12.15
The values shown on the correlation property view cannot be 
edited. Any configuration parameters available to each 
property correlation can only be edited using the Correlation 
Manager property view.
Status Bar Description
Stream Indicates that the correlation can only be applied to 
material streams.
Point/Plottable Indicates whether the property correlation is a point 
or plottable property.
Black Oil/
Electrolyte/Gas/
Petroleum/RFG/
RVP/Solid/
Standard/User/
Clone
Indicates which correlation type the property 
correlation resides within in the Available 
Correlations list.
View Selected 
Correlation icon12-20
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Streams 12-21
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ThIn the Parameters group, you can view the parameters used to 
calculate the property correlation.
In the Stream Connections group, a list of all the material 
streams currently using the property correlation is displayed.
Viewing All Correlation Plots
The View All Correlation Plots icon opens the Correlation 
Plots property view which displays all plottable properties for the 
stream. 
Active/Inactive Indicates whether the property correlation has been 
activated by the correlation manager.
If the status bar is green, any new stream added to 
the flowsheet with the same fluid type as the 
correlation will automatically have the property 
correlation added.
In Use/Not in Use Indicates whether the property correlation is being 
used by a stream in the case.
Available/
Unavailable
Indicates whether the property correlation exists in 
the window registry of the system.
To manipulate the parameter values, you have to access the 
Correlation Manager property view. 
 Figure 12.16
Status Bar Description
Refer to Section 11.18 - 
Correlation Manager in 
the HYSYS User Guide 
for more information.
View All Correlation Plots 
icon12-21
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12-22 Material Stream Property View
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ThOnly plottable properties appear on the plots property view, 
while both point and plot properties appear on the stream 
properties property view. The plot property view can show only 
one plot property at a time. 
Composition Page
The Composition page enables you to specify and manipulate 
the stream composition. 
To specify or change the stream composition do one of the 
following:
• Click the Edit button. The Input Composition property 
view appears.
• Type a value in a component cell and press ENTER. The 
Input Composition property view appears.
Blue or red colour text indicates the composition of streams 
is changeable. 
You cannot edit the compositions for a stream that is 
calculated by HYSYS. If the composition is calculated by 
HYSYS, the text colour of the composition value is black and 
the Edit button will be greyed out.
A warning appears if negative mole fraction values occur.
Refer to Input 
Composition Property 
View section for more 
information.12-22
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Streams 12-23
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ThThe figure below shows the mole fractions for each component 
in the overall phase, vapour phase, and aqueous phase. 
You can view the composition in a different basis by clicking the 
Basis button, and selecting the basis you want on the Stream 
property view.
Stream Property View
The Stream property view contains several radio buttons. The 
basis type available in HYSYS is represented by each radio 
button. 
 Figure 12.17
 Figure 12.1812-23
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12-24 Material Stream Property View
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ThTo choose a basis:
1. In the Stream property view, click one of the radio buttons 
to select a compositional basis.
2. Click the Close icon  to return to the Composition page. 
HYSYS displays the stream compositions using the selected 
basis.
Input Composition Property View
The Input Composition property view allows you to edit the 
stream compositions.  
In the Composition Basis group, select the radio button that 
corresponds to the basis for your stream. In the list of available 
components, specify the composition of the stream.
 Figure 12.1912-24
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Streams 12-25
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ThThe Composition Controls group has two buttons that can be 
used to manipulate the compositions.  
The OK button closes the Input Composition property view and 
accepts any specified changes to the stream composition.
The Cancel button closes the property view without accepting 
any changes.
Button Action
Erase Clears all compositions.
Normalize Allows you to enter any value for fractional compositions 
and have HYSYS normalize the values such that the total 
equals 1. 
This button is useful when many components are available, 
but you want to specify compositions for only a few. When 
you enter the compositions, click the Normalize button and 
HYSYS ensures the Total is 1.0, while also specifying any 
 compositions as zero. If compositions are left as 
, HYSYS cannot perform the flash calculation on 
the stream.
The Normalize button does not apply to flow compositional 
bases, since there is no restriction on the total flowrate.
For fractional bases, clicking the OK button automatically 
normalizes the composition if all compositions contain a 
value.12-25
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12-26 Material Stream Property View
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ThK Value Page
The K Value page displays the K values or distribution 
coefficients for each component in the stream.
A distribution coefficient is a ratio between the mole fraction of 
component i in the vapour phase and the mole fraction of 
component i in the liquid phase:
where:  
Ki = distribution coefficient
yi = mole fraction of component i in the vapour phase
xi = mole fraction of component i in the liquid phase
 Figure 12.20
(12.1)Ki
yi
xi
---=12-26
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Streams 12-27
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ThElectrolytes Page
If the stream is associated with an OLI-Electrolyte property 
package, the Electrolytes page displays electrolytic information.  
You can view the electrolyte stream properties or the electrolyte 
stream composition for aqueous or solid phase. In the True 
Species Info group, select the appropriate radio button to view 
the electrolyte stream properties.
The Properties radio button displays the stream fluid phase 
properties for an electrolyte system. Use the radio buttons in 
the Phase group to switch between the aqueous phase and the 
solid phase.
When you click the Aqueous phase radio button, the following 
aqueous phase related properties appear: 
• pH value
• Osmotic Pressure
• Ionic Strength
• Heat Capacity
• Viscosity 
 Figure 12.21
The Electrolytes page is available only if the stream is in an 
electrolyte system.
Refer to Section 1.2.4 - 
Adding Electrolyte 
Components in the 
HYSYS Simulation 
Basis guide for more 
information on 
electrolytes.
For more information, 
refer to Section 1.6 - 
HYSYS 
OLI_Electrolyte 
Property Package in 
the HYSYS OLI 
Interface Reference 
Guide.12-27
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12-28 Material Stream Property View
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ThWhen you click the Solid phase radio button, you can include or 
exclude a particular solid in the current stream equilibrium flash 
calculation. 
The Composition radio button displays the component name, 
molar fraction, molar flow, or molality and molarity of all the 
components in the stream for aqueous or solid phase in a table.
 Figure 12.22
 Figure 12.23
To globally include or 
exclude particular solids 
in all electrolyte 
streams, refer to 
OLI_Electrolyte 
Options section from 
Section 2.4.1 - Set Up 
Tab in the HYSYS 
Simulation Basis 
guide.
The value of Scale Tendency Index as 
shown in the table is a measure of the 
tendency of a solid species forming at 
the specified conditions. Solid with a 
scaling tendency greater than one 
forms if the solid formation is governed 
by equilibrium (as opposed to kinetics), 
and if there are no other solids with a 
common cation or anion portion which 
also has a scaling tendency greater 
than one. 
If you select the 
Aqueous radio 
button, the 
component list 
including ionic 
component(s) 
appears in the 
table.
If you select the Solid radio 
button, a component list 
including precipitate (PPT) 
and hydrated (-nH2O) solid 
appears with only mole 
fraction and mole flow.12-28
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Streams 12-29
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ThUser Variables Page
The User Variables page enables you to create and implement 
your own user variables for all material streams. 
Notes Page
The Notes page provides a text editor that allows you to record 
any comments or information regarding the material stream or 
the simulation case in general.
Cost Parameters Page
You can enter a cost factor value for the stream in the Cost 
Parameters page. You can also choose the flow basis associated 
with the cost factor from the Flow Basis drop-down list.
 Figure 12.24
For more information 
refer to Section 1.3.8 - 
User Variables Page/
Tab.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.12-29
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12-30 Material Stream Property View
ww
Th12.2.2 Attachments Tab
Unit Ops Page
The Unit Ops page allows you to view the names and types of 
unit operations and logicals to which the stream is attached. 
The property view uses three groups:
• The units from which the stream is a product.
• The units to which the stream is a feed.
• The logicals to which the stream is connected.
You can access the property view for a specific unit operation or 
logical by double-clicking in the Name cell or Type cell.
 Figure 12.2512-30
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Streams 12-31
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ThUtilities Page
The Utilities page allows you to view and manipulate the utilities 
attached to the stream.
The Utilities page allows you to do the following:
• Attach utilities to the current stream. 
• View existing utilities that are attached to the stream.
• Delete existing utilities that are attached to the stream.   
 Figure 12.26
Only the Create button is available all the time.
The View and Delete buttons are greyed out until you select 
a utility from the list.
Refer to Chapter 14 - 
Utilities for more 
information on the 
utilities available in 
HYSYS.
Refer to Section 7.26 - 
Utilities in the HYSYS 
User Guide for more 
information on adding, 
viewing, and deleting 
utilities.12-31
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12-32 Material Stream Property View
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ThDRU Stream Page
The DRU stream facilitates running a given set of unit operations 
under different stream conditions. The information gathered 
from the run are stored within the DRU stream, and can be 
either user input or acquired from the RTO system directly.
The DRU stream is used for data reconciliation to hold different 
states of streams. During data reconciliation, measured data of 
DCS tags can be obtained under different stream states (for 
example, temperature or pressure). The DRU stream can also 
perform flash calculations as other HYSYS streams do.
If you want to use the DRU stream to hold data, the number of 
data sets needs to be equal to the number of data sets of DCS 
tags. You can create data sets for streams and set values to 
stream states.
The Data Rec utility controls the updating of its associated 
streams with the correct data corresponding to the data set 
being evaluated at that point in time.
 Figure 12.27
The DRU stream is applicable for data reconciliation 
problems.
Each data set behaves as a stream (for example, the data set 
contains automatic flash calculation and freedom control).
When the Add 
Transfer Stream 
button is 
enabled, the 
Delete Transfer 
Stream button is 
disabled, and 
vice-versa.12-32
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Streams 12-33
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ThThe Add Transfer Stream button and Delete Transfer Stream 
button are solely for On-Line applications. 
• Clicking the Add Transfer Stream button creates a DRU 
Stream (Data Reconciliation Stream) such that you can 
move the information for the stream as a block between 
HYSYS cases, or instances of HYSYS. 
• Clicking the Delete Transfer Stream button removes the 
DRU Stream.
12.2.3 Dynamics Tab
The Dynamics tab displays the pressure and flow specifications 
for the material stream, and enables you to generate the strip 
chart for a set of variables.
Specs Page
The Specs page allows you to add a pressure and a flow 
specification for the stream. 
You must be in dynamic mode for any of these specifications 
to have an effect on the simulation.
 Figure 12.28
Feeder block 
or Product 
block button 
appears only 
when the 
stream is a 
flowsheet 
boundary 
stream.12-33
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12-34 Material Stream Property View
ww
ThIf the Active checkbox is selected for a specification, the value 
of the specification appears in blue and you can modify the 
value. If the Active checkbox is cleared, the value is appears in 
black and is calculated by HYSYS. Default stream conditions are 
shown in red.
Feed and Product Blocks
A flowsheet boundary stream is a stream which has only one 
unit operation attached to it. If a material stream is a flowsheet 
boundary stream, a Feeder block button or Product block button 
appears in the Specs page of the Dynamics tab. A flowsheet 
boundary stream can be the feed or product of the model. 
Depending on whether the flowsheet boundary stream is a feed 
or a product, the Dynamics tab contains either a Feeder block 
button or a Product block button. The figure below shows a 
Product Block property view of a material stream.
You can also access the Feeder Block property view by clicking 
the View Upstream Operation icon on the stream property 
view. Similarly, you can also access the Product Block property 
view by clicking the View Downstream Operation icon.
 Figure 12.29
To ignore the Feed or Product block operations, 
select the Ignored checkbox.
View Upstream Operation 
icon
View Downstream 
Operation icon12-34
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Streams 12-35
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ThThe Product Block property view displays flow reversal 
conditions of the material stream which you can specify. If 
simulation conditions are such that the product stream flow 
becomes negative, HYSYS recalls the stream conditions stored 
in the Product block and performs a rigorous flash on the 
product stream to determine the other stream conditions.
When process conditions in the simulation cause the feed flow to 
reverse, the feed stream conditions are calculated by the 
downstream operation. The Feeder Block property view is used 
to restore desired feed conditions and compositions if the feed 
stream reverses and then becomes feed again.
The Feeder Block and Product Block have similar property views. 
You can specify the stream conditions as follows: 
Since the pressure of the stream remains the same after the 
product stream flow reverses, the pressure value does not need 
to be specified. With this information, the stream is able to 
perform flash calculations on the other stream properties.
Both the Feeder Block property view and Product Block property 
view have three buttons that allow you to manipulate the 
direction of stream conditions between the material stream and 
the block. The table below briefly describes each button.:
Required Feed and Product Block Specifications
Conditions Tab Specify one of the following:
• Temperature
• Vapour Fraction
• Entropy
• Enthalpy
Composition Tab Specify the stream composition.
Block Button Action
Export Conditions to 
Stream
Copies stream conditions stored in the block to the 
material stream.
Update From Stream Copies the current stream conditions from the 
material stream to the block.
Update from Current 
Composition
Copies only the stream composition from the 
material stream to the block.12-35
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12-36 Material Stream Property View
ww
ThStripchart Page
The Stripchart page allows you to select and create default strip 
charts containing various variable associated to the material 
stream.
Refer to Section 1.3.7 - 
Stripchart Page/Tab 
for more information.12-36
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Subflowsheet Operations 13-1
ww
Th13 Subflowsheet 
Operations13-1
13.1  Introduction................................................................................. 2
13.2  Subflowsheet Property View ........................................................ 3
13.2.1  Adding a Subflowsheet ............................................................ 4
13.2.2  Connections Tab ..................................................................... 6
13.2.3  Parameters Tab ...................................................................... 8
13.2.4  Transfer Basis Tab................................................................... 9
13.2.5  Transition Tab ...................................................................... 10
13.2.6  Variables Tab ....................................................................... 14
13.2.7  Notes Tab ............................................................................ 15
13.2.8  Lock Tab.............................................................................. 16
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13-2 Introduction
ww
Th13.1 Introduction
The subflowsheet operation uses the multi-level flowsheet 
architecture and provides a flexible, intuitive method for 
building the simulation. Suppose you are simulating a large 
processing facility with a number of individual process units and 
instead of installing all process streams and unit operations into 
a single flowsheet, you can simulate each process unit inside its 
own compact subflowsheet.
Once a subflowsheet operation is installed in a flowsheet, its 
property view becomes available just like any other flowsheet 
object. Think of this property view as the “outside” property 
view of the “black box” that represents the subflowsheet. Some 
of the information contained on this property view is the same 
as that used to construct a Template type of Main flowsheet. 
Naturally this is due to the fact that once a Template is installed 
into another flowsheet, it becomes a subflowsheet in that 
simulation.
Whether the flowsheet is the Main flowsheet of a simulation 
case, or it is contained in a subflowsheet operation, it possesses 
the following components:
• Fluid Package. An independent fluid package, 
consisting of a Property Package, Components, and so 
forth. It is not necessary that every flowsheet in the 
simulation have its own separate fluid package. More 
than one flowsheet can share the same fluid package.
• Flowsheet Objects. The inter-connected topology of 
the flowsheet. Unit operations, material and energy 
streams, utilities, and so forth.
• A Dedicated PFD. A HYSYS property view presenting a 
graphical representation of the flowsheet, showing the 
inter-connections between flowsheet objects.
• A Dedicated Workbook. A HYSYS property view of 
tabular information describing the various types of 
flowsheet objects. 
• A Dedicated Desktop. The PFD and Workbook are 
home property views for this Desktop, but also included 
are a menu bar and a toolbar specific to either regular or 
Column subflowsheets.13-2
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Subflowsheet Operations 13-3
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Th13.2 Subflowsheet 
Property View
The Subflowsheet property view consists of the following tabs: 
• Connections
• Parameters
• Transfer Basis
• Mapping
• Variables
• Notes
• Lock
 Figure 13.1
Click this button to enter the subflowsheet 
environment.13-3
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13-4 Subflowsheet Property View
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Th13.2.1 Adding a Subflowsheet
There are two ways you can add a subflowsheet to your 
simulation.
1. Select Flowsheet | Add Operation command from the 
menu bar. The UnitOps property view appears.
You can also access the UnitOps property view by pressing 
F12.
2. Click the Sub-Flowsheets radio button.
3. From the list of available unit operations, select Standard 
Sub-Flowsheet.
4. Click the Add button.
OR
1. Select Flowsheet | Palette command from the menu bar. 
The Object Palette appears.
You can also open the Object Palette by pressing F4.
2. Double-click on the Sub-Flowsheet icon on the Object 
Palette.
The Sub-Flowsheet Option property view appears.
The Sub-Flowsheet Option property view contains the following 
options:
• Read an Existing Template
• Start with a Blank Flowsheet
• Paste exported objects
• Cancel
 Figure 13.2
Sub-Flowsheet icon13-4
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Subflowsheet Operations 13-5
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ThRead an Existing Template
If you want to use a previously constructed Template that has 
been saved on disk, click the Read an Existing Template button 
on the Sub-Flowsheet Option property view. 
Start with a Blank Flowsheet
If you want to start with a blank subflowsheet, click the Start 
with a Blank Flowsheet button on the Sub-Flowsheet Option 
property view, HYSYS will install a subflowsheet operation 
containing no unit operations or streams. 
On the Connections tab of the property view of the blank 
subflowsheet, there will be no feed or product connections 
(boundary streams) to the subflowsheet. You can connect feed 
streams in the External Stream column by either typing in the 
name of the stream to create a new stream or selecting a pre-
defined stream from a drop-down list. When an external feed 
connection is made by selecting a pre-defined stream from the 
drop-down list, a stream similar to the pre-defined stream is 
created inside the subflowsheet environment.
In order to fully define the flowsheet, you have to enter the 
subflowsheet environment. Click the Sub-Flowsheet 
Environment button on the property view to transition to the 
subflowsheet environment and its dedicated Desktop. The 
subflowsheet is constructed using the same methods as the 
main flowsheet. When you return to the Parent environment, 
you can connect the subflowsheet boundary streams to streams 
in the Parent flowsheet.
Paste Exported Objects
If you want to import previously exported objects into a new 
subflowsheet, click the Paste Exported Objects button on the 
Sub-Flowsheet Option property view. 
For more information, 
refer to Section 3.5.2 - 
Creating a Template 
Style Flowsheet in the 
HYSYS User Guide.13-5
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13-6 Subflowsheet Property View
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ThYou copy and paste selected objects inside the same 
subflowsheet or another subflowsheet. You can also copy and 
paste subflowsheets and column subflowsheets. Objects can 
also be moved into or out of a subflowsheet.
13.2.2 Connections Tab 
You can enter the name of the subflowsheet, as well as its Tag 
name, on the Connections tab. All feed and product connections 
appear on the Connections tab.
Flowsheet Tags
These short names are used by HYSYS to identify the flowsheet 
associated with a stream or operation when that flowsheet 
object is being viewed outside of its native flowsheet scope. The 
default Tag name for a subflowsheet operation is TPL1 (for 
Template). 
The objects that are selected and exported via the PFD can 
be imported back into a flowsheet without creating a new 
subflowsheet first. 
 Figure 13.313-6
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Subflowsheet Operations 13-7
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ThWhen more than one subflowsheet operation is installed, HYSYS 
ensures unique tag names by incrementing the numerical suffix; 
the subflowsheets are numbered sequentially in the order they 
were installed. For example, if the first subflowsheet added to a 
simulation contained a stream called Comp Duty, it would 
appear as Comp Duty@TPL1 when viewed from the Main 
flowsheet of the simulation.
Feed and Product Connections
Internal streams are the boundary streams within the 
subflowsheet that can be connected to external streams in the 
Parent flowsheet. Internal streams cannot be specified on this 
tab, they are automatically determined by HYSYS. Basically, any 
streams in the subflowsheet that are not completely connected 
(in other words,”open ended”) can serve as a feed or product.  
To connect the subflowsheet, specify the appropriate name of 
the external streams, which are in the Parent flowsheet, in the 
matrix opposite the corresponding internal streams, which are in 
the subflowsheet. The stream conditions are passed across the 
flowsheet boundary via these connections.      
Subflowsheet streams that are not connected to any unit 
operations in the subflowsheet appear in the property view 
as well (and are termed “dangling streams”).
 Figure 13.4
It is not necessary to specify an external stream for each 
internal stream.13-7
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13-8 Subflowsheet Property View
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Th13.2.3 Parameters Tab
You can view the exported subflowsheet variables on the 
Parameters tab, which allows you to keep track of several key 
variables without entering the subflowsheet environment or 
adding the variables to the global DataBook. It is also useful 
when dealing with a subflowsheet as a black box. The user who 
created the subflowsheet can set up an appropriate Parameters 
tab, and another user of the subflowsheet can be unaware of the 
complexities within the subflowsheet.
These variables display values, which have been calculated or 
specified by the user. If changes to the specified values are 
made here, the subflowsheet is updated accordingly. For each 
variable, the description, value, and units are shown.
• The Ignore checkbox is used to bypass the subflowsheet 
during calculations, just as with all HYSYS unit 
operations.
• The Update Outlets checkbox enables you to toggle 
between transferring or not transferring updated values 
from the subflowsheet to the external streams.
 Figure 13.5
These variables are actually added on the Variables Tab of 
the property view, but are viewed in full detail on the 
Parameters tab.13-8
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Subflowsheet Operations 13-9
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Th13.2.4 Transfer Basis Tab
The transfer basis for each Feed and Product Stream is listed on 
the Transfer Basis tab. 
The transfer basis only becomes significant when the 
subflowsheet and Parent flowsheet's fluid packages consist of 
different property methods. The transfer basis is used to provide 
a consistent means of switching between the different basis of 
the various property methods. The table below list all the 
possible transfer basis provided by HYSYS: 
 Figure 13.6
The Transfer Basis is also useful in controlling VF, T, or P 
calculations in column subflowsheet boundary streams with 
close boiling or nearly pure compositions.
Transfer Basis Description
T-P Flash The Pressure and Temperature of the Material stream 
are passed between flowsheets. A new Vapour Fraction 
is calculated.
VF-T Flash The Vapour Fraction and Temperature of the Material 
stream are passed between flowsheets. A new 
Pressure is calculated.
VF-P Flash The Vapour Fraction and Pressure of the Material 
stream are passed between flowsheets. A new 
Temperature is calculated.13-9
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13-10 Subflowsheet Property View
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Th13.2.5 Transition Tab
The Transition tab allows you to select and modify the stream 
transfer and map methods for the fluid component composition 
across fluid package boundaries.
You may choose between three transition types: FluidPkg 
Transition, Basis Transition, and Black Oil Transition.
Fluid Package Transition  
Composition values for individual components from one fluid 
package can be mapped to a different component in an 
alternate fluid package. Mapping is especially useful when 
dealing with hypothetical oil components where like components 
from one fluid package can be mapped across the subflowsheet 
P-H Flash The Pressure and Enthalpy of the Material stream are 
passed between flowsheets.
User Specs You define the properties passed between flowsheets 
for a Material stream.
None Required No calculation is required for an Energy stream. The 
heat flow is simply passed between flowsheets.
 No transfer basis has been selected.
 Figure 13.7
Transfer Basis Description13-10
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Subflowsheet Operations 13-11
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Thboundary to another fluid package.
Basic Transition
The Basic Transition view outlines the value of each component 
within the Inlet Stream Molar Composition and the Outlet 
Stream Molar Composition. 
Component Maps can also be created and edited in the Basis 
environment.
 Figure 13.8
Refer to Section 6.2 - 
Component Maps Tab 
in the HYSYS 
Simulation Basis guide 
for more information.13-11
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13-12 Subflowsheet Property View
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ThBlack Oil Transition
The Black Oil Transition view allows you to:
• Choose between three sperarate Black Oil Transition 
Methods:
- Simple
- Three Phase
- Infochem Mulitflash
• Select the Oil Phase Cut Options from the drop-down list.
• View/Edit the Composition of the stream.
• Erase the Compostion of the stream.
• Normalize the Composition of the stream.
For every pairing of different fluid packages, a collection of maps 
exists. Component maps can be added to each collection on the 
Component Maps tab in the Simulation Basis Manager property 
view.
To select a transfer and map method for the inlet and outlet 
streams:
1. In the approriate cell under the Transition column, click the 
 Figure 13.913-12
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Subflowsheet Operations 13-13
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Thdown arrow icon  to open the drop-down list.
2. In the drop-down list, select the transition type you want to 
apply to the stream.
3. Repeat the above steps for all the streams that require a 
transition method.
To modify the type of transfer and map method for inlet and 
outlet streams:
1. Under the Stream column, click on the cell containing the 
stream you want to modify.
2. Click the appropriate View Transition button in the group.
The Transition property view of the selected stream appears.
3. In the Transition property view, you can make the following 
changes:
• modify the fluid package of the streams
• edit, add, or delete a component map method
• modify the transfer basis
4. Click the Imbalance button to view the component 
imbalance in the selected stream.
To view overall component imbalance for streams flowing 
through the subflowsheet:
1. Click the Overall Imbalance Into Sub-Flowsheet button 
Some of the transition method require the RefSYS or 
Upstream license to run.
 Figure 13.1013-13
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13-14 Subflowsheet Property View
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Thor Overall Imbalance Out of Sub-Flowsheet button to 
open the Untransferred Component Info property view. 
The Untransferred Component Info property view allows you 
to confirm that all of the components have been transferred 
into or out of the subflowsheet.
2. Click the appropriate radio button to view the imbalance in 
molar, mass, or liquid volume basis.
13.2.6 Variables Tab
The Variables tab of the Main flowsheet property view allows you 
to create and maintain the list of externally accessible variables. 
Although you can access any information inside the 
subflowsheet using the Variable Navigator, the features on the 
Variables tab allow you to target key process variables inside the 
subflowsheet and display their values on the property view. 
Then, you can conveniently view this whole group of information 
directly on the subflowsheet property view in the Parent 
flowsheet.
To add variables:
1. Click the Add button. The Variable Navigator property view 
 Figure 13.11
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information on the 
Variable Navigator.13-14
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Subflowsheet Operations 13-15
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Thappears.
2. On the Variable Navigator property view, select the 
flowsheet object and variable you want.
You can also over-ride the default variable description 
displayed in the Variable Description field of the Variable 
Navigator property view.
13.2.7 Notes Tab
The Notes tab provides a text editor where you can record any 
comments or information regarding the material stream or to 
your simulation case in general.
Any subflowsheet variables added in the Variables tab will 
appear on the Parameters tab. 
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.13-15
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13-16 Subflowsheet Property View
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Th13.2.8 Lock Tab
The Lock tab enables you to lock or unlock the subflowsheet and 
displays the lock status of the subflowsheet.
When the flowsheet is locked, you cannot create or delete 
objects, or change the topology. You can add Set, Adjust, and 
Spreadsheet operations; manipulate variable values; or copy 
the contents of the flowsheet and create your own modifiable 
version.
• To lock a subflowsheet, enter a password in the Lock 
Status field and press ENTER. 
• To unlock a subflowsheet, enter the correct password in 
the Lock Status field and press ENTER. 
 Figure 13.12
Subflowsheets inside a locked subflowsheet have to be 
specifically locked.13-16
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Utilities 14-1
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Th14 Utilitiesw.cadfamily.com    EMa
e document is for study 14.1  Introduction................................................................................. 4
14.2  Boiling Point Curves..................................................................... 7
14.2.1  Design Tab ............................................................................ 8
14.2.2  Performance Tab .................................................................. 10
14.2.3  Dynamics Tab ...................................................................... 13
14.3  CO2 Solids.................................................................................. 14
14.3.1  Design Tab .......................................................................... 15
14.3.2  Dynamics Tab ...................................................................... 16
14.4  Cold Properties .......................................................................... 17
14.4.1  Design Tab .......................................................................... 18
14.4.2  Performance Tab .................................................................. 21
14.4.3  Dynamics Tab ...................................................................... 22
14.5  Composite Curves Utility ............................................................ 23
14.5.1  Design Tab .......................................................................... 23
14.5.2  Performance Tab .................................................................. 25
14.6  Critical Properties ...................................................................... 29
14.6.1  Design Tab .......................................................................... 31
14.6.2  Dynamics Tab ...................................................................... 32
14.7  Data Reconciliation Utility.......................................................... 33
14.7.1  Data Reconciliation Utility Property View .................................. 35
14.7.2  Optimization Objects............................................................. 48
14.7.3  DRU Diagnostic File Output .................................................... 53
14.8  Derivative Utility........................................................................ 5914-1
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14-2 Utilities 
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The document is for study 14.9  Dynamic Depressuring................................................................60
14.9.1  Design Tab ...........................................................................64
14.9.2  Worksheet Tab ......................................................................84
14.9.3  Performance Tab ...................................................................85
14.10  Envelope Utility ........................................................................87
14.10.1  HYSYS Two-Phase Envelope ..................................................87
14.10.2  Three-phase Envelope Utility.................................................94
14.11  FRI Tray Rating Utility ............................................................110
14.11.1  Inputs Tab ........................................................................111
14.11.2  Results Tab.......................................................................118
14.11.3  Tray Properties Tab ............................................................124
14.12  Hydrate Formation Utility .......................................................126
14.12.1  Design Tab .......................................................................134
14.12.2  Performance Tab ...............................................................137
14.12.3  Dynamics Tab ...................................................................140
14.13  Master Phase Envelope Utility.................................................142
14.13.1  Design Tab .......................................................................142
14.13.2  Performance Tab ...............................................................143
14.14  Parametric Utility....................................................................145
14.14.1  Neural Networks................................................................146
14.14.2  Variables ..........................................................................148
14.14.3  PM Utility Property View .....................................................149
14.14.4  Neural Network (NN) Manager.............................................164
14.15  Pipe Sizing..............................................................................172
14.15.1  Design Tab .......................................................................172
14.15.2  Performance Tab ...............................................................175
14.16  Property Balance Utility ..........................................................176
14.16.1  Material Balance Tab ..........................................................178
14.16.2  Energy Balance Tab ...........................................................185
14.17  Property Table ........................................................................187
14.17.1  Design Tab .......................................................................188
14.17.2  Performance Tab ...............................................................19214-2
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14-3 Utilities 
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The document is for study 14.17.3  Dynamics Tab ...................................................................195
14.18  Tray Sizing..............................................................................196
14.18.1  Design Tab .......................................................................198
14.18.2  Performance Tab ...............................................................222
14.18.3  Dynamics Tab ...................................................................227
14.18.4  Auto Section .....................................................................227
14.19  User Properties.......................................................................231
14.19.1  Design Tab .......................................................................232
14.19.2  Performance Tab ...............................................................233
14.20  Vessel Sizing...........................................................................235
14.20.1  Design Tab .......................................................................235
14.20.2  Performance Tab ...............................................................240
14.21  References..............................................................................24114-3
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14-4 Introduction
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Th14.1 Introduction
The utility commands are a set of tools, which interact with a 
process by providing additional information or analysis of 
streams or operations. In HYSYS, utilities become a permanent 
part of the Flowsheet and are calculated automatically when 
appropriate. They can also be used as target objects for Adjust 
operations.
 Most utilities can also be added through the Utilities page on 
the Attachments tab of a stream's property view. A utility added 
through either route is automatically updated in the other 
location. For example, if you attach an Envelope utility to a 
stream using the Available Utilities property view, the Envelope 
utility automatically appears on the Utilities page of the 
Attachments tab in the property view of the stream to which it 
was attached.
You can select any of the following utilities from the Available 
Utilities property view:
Utilities Description
Boiling Point Curves Obtains laboratory-style distillation results for 
streams.
CO2 Freeze Out Determines stream CO2 freezing conditions.
Cold Properties Calculates several stream Cold Properties, for 
example True and Reid Vapour Pressures, Flash 
Point, Pour Point, Refractive Index, and so forth.
Composite Curves Optimizes the use of process heat exchange and 
utilities for heat exchangers, LNG's, coolers, and 
heaters.
Critical Properties Calculates true and pseudo critical properties for 
streams.
Data Recon Used by HYSYS.RTO optimization objects as a 
data holder that allows for multiple sets of stream 
data, each corresponding to a different set.
Depressuring-
Dynamics
Models the pressure letdown of a single vessel or 
network of vessels under plant emergency 
conditions.
Derivative Used by HYSYS.RTO to hold all the data used for 
defining the RTO optimizer constraints and 
variables.
Envelope Shows critical values and phase diagrams for a 
stream.
For information on adding 
the utilities using the 
Available Utilities 
property view, refer to 
the section on Adding a 
Utility.
For further details, refer 
to Chapter 1 in the 
Aspen RTO Reference 
Guide.
For further details, refer 
to Chapter 1 in the 
Aspen RTO Reference 
Guide.14-4
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Utilities 14-5
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ThAdding a Utility
1. Select Tools | Utilities command from the menu bar. The 
Available Utilities property view appears.
You can also access the Available Utilities property view by 
pressing CTRL U.
2. From the list of available utilities, in the right pane, select 
the utility you want to add.
3. Click the Add Utility button. The selected utility’s property 
view appears.
Editing a Utility
1. Select Tools | Utilities command from the menu bar. The 
Available Utilities property view appears.
2. From the list of installed utilities, in the left pane, select the 
utility you want to view.
3. Click the View Utility button. The selected utility’s property 
view appears. From here, you can modify any of the utility’s 
properties.
Hydrate Formation Determines stream hydrate formation conditions.
Parametric The Parametric Utility integrates Neural Network 
(NN) technology into its framework. The major 
function of the utility is to approximate an existing 
HYSYS model with a parametric model.
Pipe Sizing Performs design calculations on any of the case 
streams.
Property Balance Performs balance calculations across any utilities. 
You can select individual utilities or the entire 
flowsheet.
Property Table Examines stream property trends over a range of 
conditions.
Tray Sizing Size or rate existing sections or full towers.
User Property Defines new stream properties based on 
composition.
Vessel Sizing Size and cost installed Separator Unit Operations.
Utilities Description14-5
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14-6 Introduction
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ThDeleting a Utility
1. Select Tools | Utilities command from the menu bar. The 
Available Utilities property view appears.
2. From the list of installed utilities, in the left pane, select the 
utility you want to delete.
3. Click the Delete Utility button. HYSYS will ask you to 
confirm the deletion.
Ignoring a Utility
To ignore a utility during simulation calculations:
1. Select Tools | Utilities command from the menu bar. The 
Available Utilities property view appears.
2. From the list of installed utilities, in the left pane, select the 
utility you want to view.
3. Click the View Utility button. The selected utility’s property 
view appears.
4. Select the Ignored checkbox, which is usually located on 
right bottom corner of the utility’s property view. 
HYSYS disregards the utility entirely until you restore the 
utility to an active state by clearing the Ignored checkbox.
You can also delete a utility by clicking the Delete button on 
the utility’s property view.14-6
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Utilities 14-7
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Th14.2 Boiling Point Curves
The Boiling Point Curves utility, which generally is used in 
conjunction with characterized oils from the Oil Manager, allows 
you to obtain the results of a laboratory style analysis for your 
simulation streams. Simulated distillation data including TBP, 
ASTM D86, D86 (Corr.), D1160(Vac), D1160(Atm), and D2887 
as well as critical property data for each cut point and cold 
property data are calculated. The data can be viewed in a 
tabular format or graphically.
The object for the analysis can be a stream, a phase on any 
stage of a tray section, or one of the phases in a separator, in a 
condenser or in a reboiler. You select the basis for the 
calculations, and you can specify the boiling ranges for the 
simulated distillation data.
 Figure 14.1
Refer to Chapter 4 - 
HYSYS Oil Manager in 
the HYSYS Simulation 
Basis guide for details 
on the distillation data 
types.
To add the Boiling Point 
Curves utility, refer to 
the section on Adding a 
Utility.14-7
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14-8 Boiling Point Curves
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Th14.2.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
On the Connections page, you can select the parameters for the 
Boiling Point Curves utility.
Setting the Utility Parameters
1. On the Connections page of the Design tab, change the 
Name of the utility, if desired.
2. From the Object Type drop-down list, select the object type 
you want. The options are Stream, Tray Section, Separator, 
Condenser, or Reboiler.
For a tray section, the boiling point curves and critical 
property data can be accented on the Profiles tab of the 
Column Runner.
 Figure 14.214-8
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Th3. Click the Select Object button, the Select (object type) 
view appears. 
The title of the Select (object type) view depends on the 
object type you selected. For example, if you select the 
condenser, the Select Condenser property view appears.
4. Choose the appropriate object from the Object list, and click 
the OK button to add the selected object to the utility.
The Object list can be filtered by selecting one of the radio 
buttons in the Object Filter group.
5. From the Basis drop-down list, select the basis for the 
calculation of the distillation data. The options are Mole Frac, 
Mass Frac, Liquid Volume.
6. For all object types except the Stream selection, from the 
Phase drop-down list you can select the phase for the 
analysis as either Vapour or Liquid.
7. If the Object Type which you have selected is a Tray Section, 
from the Stage drop-down list select a stage.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
 Figure 14.3
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-9
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14-10 Boiling Point Curves
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Th14.2.2 Performance Tab
The Performance tab contains the following pages:
• Results
• Critical Props
• Cold Props
• Plots
Results Page
You can view the results of the boiling point curve calculations in 
tabular format on the Results page. 
Simulated distillation profiles are provided for the following 
assay types:
• TBP
• ASTM D86
• D86 Corr.
• ASTM D1160 (Vac.)
• ASTM D1160 (Atm.)
• ASTM D2887
 Figure 14.414-10
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Utilities 14-11
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ThThe ASTM D86 boiling point curve corresponds to the true 
boiling points of the oil, which assumes no cracking has 
occurred.
When the oil is characterized by a ASTM D86 distillation assay 
with no cracking option, the D86 Corr boiling point curve 
corresponds to the assay input data. The ASTM D86 boiling point 
curve then corresponds to raw lab data, with no cracking 
correction applied. 
When the oil is characterized by a ASTM D86 distillation assay 
with cracking option, the ASTM D86 boiling point curve 
corresponds to the assay input data. The cracking correction 
factor is then applied to the D86 Corr boiling point curve. 
[American Society for Testing Materials, part 23, Philadelphia, 
PA (1982)]
Critical Props Page
The Critical Props page contains, for each cut point, the critical 
temperature, critical pressure, acentric factor, molecular weight, 
and liquid density.
 Figure 14.514-11
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14-12 Boiling Point Curves
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ThCold Props Page
You can view the bulk cold properties of the stream on the Cold 
Props page. Also listed is the ratio of paraffins to naphthas to 
aromatics.
Plots Page
The Plots page shows the Boiling Point Curves results and the 
Critical Properties results in graphical form. Examine the plot of 
your choice by making a selection from the Dependent Variable 
drop-down list:
• Boiling Point Curves
• Critical Temperature
• Critical Pressure
• Acentric Factor
• Molecular Weight
• Liquid Density
You can customize a plot by right-clicking in the plot area, and 
selecting Graph Control command from the object inspect 
menu.
 Figure 14.6
Details of the methods 
used to determine the 
Cold Properties can be 
found in Section 14.4 - 
Cold Properties.
Refer to Section 1.3.1 - 
Graph Control 
Property View for 
more information.14-12
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ThThe figure below shows an example of the Plots page.
14.2.3 Dynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that 
the utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
The Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities, and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.
The Calculate Now button allows you to calculate in dynamics 
mode when the integrator is not running.
 Figure 14.714-13
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14-14 CO2 Solids
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Th14.3 CO2 Solids
An equation-of-state based approach is used to calculate the 
incipient solid formation point for mixtures containing Carbon 
Dioxide (CO2). The model can be used for predicting the initial 
solid formation point in equilibrium with either vapours or 
liquids. The fugacity of the resultant solid is obtained from the 
known vapour pressure of solid CO2. The fugacity of the 
corresponding phase (in equilibrium with the solid) is calculated 
from the equation of state.  
 Figure 14.8
CO2 Solids prediction is restricted to the Peng Robinson (PR) 
and Soave Redlich Kwong (SRK) equations of state.
To add the CO2 Freeze 
Out utility, refer to the 
section on Adding a 
Utility.14-14
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Utilities 14-15
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Th14.3.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
You are required to specify the stream for which the calculations 
are made on the Connections page. 
You can select the stream from the Select Process Stream 
property view, which is accessed by clicking the Select Stream 
button.
HYSYS determines the CO2 Freeze Temperature, and displays 
the formation status in the Formation Flag field:
 Figure 14.9
Formation Flag Flag Significance
Undetermined No Stream has been chosen.
NO CO2 in 
Stream 
There is no CO2 present in the Stream.14-15
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14-16 CO2 Solids
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ThIn the Tolerance field, you can specify the tolerance used to 
calculate the incipient solid formation point.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.3.2 Dynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
Does NOT Form Solid CO2 not form at the present conditions of the 
stream. The CO2 Freeze Temperature is shown in the 
corresponding field.
Solid CO2 
Present 
Solid CO2 is present at the current stream conditions. 
The CO2 Freeze Temperature is shown in the 
corresponding field.
 Figure 14.10
Formation Flag Flag Significance
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-16
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Utilities 14-17
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ThThe Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities, and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox enables the Use Default 
Periods feature for use in Dynamic mode.
14.4 Cold Properties
The Cold Properties utility enables you to view the cold 
properties of a stream.
The following list summarizes the cold properties which are 
available through the Cold Properties utility:
 Figure 14.11
To add the Cold 
Properties utility, refer 
to the section on 
Adding a Utility.
Cold Property Calculations Range of Validity
True Vapour Pressure @ 100°F 
(37.8°C)
Vapour Pressure method of 
selected property package
P>1.5 kPa
Reid Vapour Pressure @ 100°F 
(37.8°C)
Vapour pressure of system 
when vapour:liquid ratio by 
volume is 4:1
P>1.5 kPa14-17
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14-18 Cold Properties
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Th14.4.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Flash Point As per API 2B7.1 150°F70
Cold Property Calculations Range of Validity14-18
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Utilities 14-19
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ThConnections Page
You can attach a stream to the utility, view the streams 
properties, and select the calculation methods for certain 
property values on the Connections page.
The View Picker offers two views: Values and Options. Values 
displays the following property values in the Properties group:
• True Vapour Pressure
• Reid Vapour Pressure
• Flash Point
• Pour Point
• Refractive Index
• Cetane Index
• Research Octane Number
• Viscosity at 100°F (37.8°C) and 210°F (98.6°C)
Options allows you to view and choose the calculation methods 
 Figure 14.1214-19
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14-20 Cold Properties
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Thfor the property values.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
Calculation Options
Reid VP at 37.8 C • HYSYS RVP (default)
• Aspen RVP-API
Flash Point • HYSYS Flash Point API (default)
• Aspen Pennsky-Martens
• Aspen Tag
Cetane Index • HYSYS Default (default)
• Aspen Collins-Unzelman
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-20
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Utilities 14-21
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Th14.4.2 Performance Tab
The Performance tab contains a BP and a PNA page.
BP Page
The BP page displays the simulated distillation profiles for ASTM 
D86 and D86 Crack Reduced assay types at 10%, 30%, 50%, 
70%, and 90%. You can change the calculation method for the 
D86 Distillation Curves by clicking the drop down arrow next to 
the ASTMD86 field in the Calculation Methods group.
PNA Page 
The PNA page displays the ratio of paraffins to naphthenes to 
aromatics.
The default calculation method for the D86 Distillation 
Curves is the method chosen in the Tools | Preferences 
window. If the method is changed to API 1987, any new Cold 
Properties Utility will have the HYSYS API 1987 method 
chosen for the D86 curves. Existing Cold Property Utilities 
will not be affected.14-21
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14-22 Cold Properties
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Th14.4.3 Dynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
The Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities, and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.
 Figure 14.1314-22
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Utilities 14-23
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Th14.5 Composite Curves 
Utility
Pinch technology is a methodology, which is used to optimize 
the use of process heat exchange and utilities in complicated 
processes. The HYSYS Composite Curves utility provides the 
necessary tools to apply the pinch principles in the design of 
efficient heat exchanger networks. For further pinch analysis 
information, refer to the text by Marsland1.
You can attach any combination of heat exchangers, LNG 
operations, heaters or coolers to the Composite Curves utility. 
The only requirement being that each operation is solved so the 
Pinch calculations can be performed. 
14.5.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
 Figure 14.14
To add the Composite 
Curves utility, refer to 
the section on Adding a 
Utility.14-23
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14-24 Composite Curves Utility
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ThConnections Page
On the Connections page, you can attach any combination of 
heat exchangers, LNG operations, heaters, and coolers to the 
utility.
Adding a Heat Exchanger Object
1. On the Connections page of the Design tab, click the 
Select Heat Exchanger Object button. 
2. The Select Heat Exchanger Object property view appears. 
3. From the property view, select the heat exchanger, LNG, 
heater or cooler you want from the Object list.
The Object list can be filtered by selecting one of the radio 
buttons in the Object Filter group.
4. Click the OK button to add the selected object to the utility.
 Figure 14.1514-24
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Utilities 14-25
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ThRemoving a Heat Exchanger Object
1. On the Connections page of the Design tab, select the 
heat exchanger object you want to remove from the list.
2. Press the DELETE button.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.5.2 Performance Tab
The Performance tab contains the following pages: 
• Side Results
• Pinch Results
• Table
• Plots
 Figure 14.16
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-25
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14-26 Composite Curves Utility
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ThSide Results Page
On the Side Results page, you can view the inlet temperature, 
outlet temperature, and molar flow of each pass attached to the 
Composite Curves utility. 
Pinch Results Page
The various results of the Composite Curves utility can be 
examined on the Pinch Results page. 
The results which can be examined include the following:
• Hot Pinch Temperature
• Cold Pinch Temperature
• Minimum Approach. Temperature difference between 
the Hot Pinch and Cold Pinch.
• Average Temperature at Pinch
• Enthalpy Change at Pinch
 Figure 14.17
 Figure 14.1814-26
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Utilities 14-27
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Th• Cold Utility
• Hot Utility
• Number of Points. The number of intervals used in the 
Composite Curves utility calculations.
• Minimum Approach Target. Specifiable minimum 
approach temperature.
• Cold Utility Target. Specifiable cold utility enthalpy 
value.
• Hot Utility Target. Specifiable hot utility enthalpy 
value.
Table Page
The Table page shows a tabular report of what is seen on the 
Plots page. You can view temperatures of the Sink and Source, 
the LMTD and enthalpy change for each interval.
 Figure 14.1914-27
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14-28 Composite Curves Utility
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ThPlots Page
On the Plots page, you can view the Sink and Source Composite 
Curves or the Grand Composite Curve. Make your selection from 
the Graph Type drop-down list. The Composite Curves for the 
heat exchanger network is shown in the figure below. Notice the 
pinch also appears on this plot.
You can edit the plot by right-clicking anywhere in the plot area, 
and selecting the Graph Control command from the object 
inspect menu. 
 Figure 14.20
Refer to Section 1.3.1 - 
Graph Control Property 
View for more 
information about 
manipulating plots.14-28
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Utilities 14-29
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Th14.6 Critical Properties
The Critical Properties utility calculates both the true and pseudo 
critical temperature, pressure, volume, and compressibility 
factor for a fully defined stream.
True & Pseudo Critical Properties 
The Critical Properties utility displays two sets of critical 
properties, true and pseudo critical properties. True Critical 
Properties are those properties calculated using the mixing 
rules associated with the property package chosen. Pseudo 
Critical Properties use simple linear models to estimate the 
critical properties of a mixture. They are often very different 
from the true critical points and have no real physical 
significance, but sometimes are used in empirical correlations.
Mathematically, the pseudo critical temperature, pressure, and 
compressibility (Tpc, Ppc, and Zpc) are defined as: 
(14.1)
(14.2)
(14.3)
To add the Critical 
Properties utility, refer 
to the section on 
Adding a Utility.
Tpc yiTci
i 1=
n
∑=
Ppc yiPci
i 1=
n
∑=
Zpc yiZci
i 1=
n
∑=14-29
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14-30 Critical Properties
ww
Thwhere:  
yi = mole fraction of component i
n = total number of components in mixture
Tci = critical temperature of component i
Pci = critical pressure of component i
Zci = critical compressibility of component i
The remaining pseudo critical property, pseudo critical volume 
vpc, is calculated using the following relationship:  
(14.4)
 Figure 14.21
You must set up a fluid package using the Peng Robinson 
property method to use this utility.
vpc
ZpcTpcR
Ppc
--------------------=14-30
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Utilities 14-31
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Th14.6.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
You can connect the utility to a stream, and change the name of 
the utility on this page.
The following is the general procedure for connecting a stream 
to the Critical Properties utility:
1. On the Critical Properties property view, specify the name of 
the utility.
2. Click the Select Stream button. The Select Process Stream 
property view appears.
3. Select the stream you created from the Object list.
The Object list can be filtered by selecting one of the radio 
buttons in the Object Filter group.
4. Click the OK button to add the selected stream to the utility.
 Figure 14.2214-31
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14-32 Critical Properties
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ThCritical Property Analysis
You can examine the critical property values for the selected 
stream in the Properties group.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the utility or your simulation 
case in general.
14.6.2 Dynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
 Figure 14.23
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-32
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Utilities 14-33
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ThThe Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities, and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.
14.7 Data Reconciliation 
Utility
Modern instrumentation and distributed control and 
management information systems produce a wealth of plant 
data. The plant operator/manager has a problem making sense 
of all this data where:
• It may be inconsistent or inaccurate.
• It may not give a complete or understandable indication 
of plant performance.
In addition, plant models can only be configured to a specific 
operational instance, whereas the performance of actual 
equipment varies as conditions change and equipment 
degrades. Thus, the model behaviour may start to diverge from 
actual plant behaviour.
The Data Reconciliation Utility (DRU) addresses these issues 
and produces concise information to aid decision making and aid 
model tuning and off-line investigation.
To add the Data Recon 
utility, refer to the 
section on Adding a 
Utility.14-33
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14-34 Data Reconciliation Utility
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ThFirstly, it can perform data reconciliation. Measurements are 
subject to error and, therefore, provide inconsistent 
information. DRU can detect and correct measurement errors, 
thereby providing a consistent and accurate data set.
Secondly, a model representing a specific item of plant can be 
updated whereby DRU is able to reconcile model and actual 
plant values, to ensure that the model continues to represent 
actual plant performance.
The DRU brings real benefits by ensuring good representation of 
plant equipment, and providing indications of poor plant data as 
an aid to decision making in the following areas:
• Identification of process unit performance, in particular 
condition monitoring.
• Identification and quantification of instrument errors.
This leads to improvements due to:
• Better process operation in general.
• More effective and efficient equipment maintenance and/
or replacement.
• More effective and efficient instrument maintenance.
• Improved plant model representation.
Current applications of the DRU include:
• Compressor model updating/condition monitoring
• Catalyst performance monitoring/updating
• Thermal cracker model updating
• Steam system data reconciliation
• Gas turbine model parameter updating
• Heat exchanger fouling effect updating
• Reactor model parameter updating
• Boiler model updating and condition monitoring
• General network reconciliation (e.g., oil & gas fields, 
steam systems, etc.)
In fact, anywhere where plant measurements are available 
around process equipment, the DRU can be applied.14-34
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Utilities 14-35
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ThThe DRU offers the following facilities:
• Error Detection/Correction - No measurement is 
perfect, so by using a number of sets of data and 
statistical routines, the DRU sorts the good from the bad 
and only uses good data. This is a pre-requisite for model 
updating and the essence of data reconciliation.
• Model Updating - The DRU can update the parameters 
of even the most complex model.
• Utilities - The DRU invokes a number of statistical and 
optimization routines to perform the following tasks:
- Parameter Estimation - Calculation of model 
parameters which may change with time, such as 
reaction rate coefficients, heat transfer coefficients, 
etc.
- Data Reconciliation - Model based reconciliation of 
over-determined systems, such as steam system 
mass balancing, where there are many flow-meters, 
or estimation of power output of a turbine with both 
steam flow and driven load being measured.
- Bad Data Elimination - Results of data 
reconciliation calculations can be examined 
statistically to determine whether bad data is 
present, and if so eliminate the bad data.
14.7.1 Data Reconciliation 
Utility Property View
Four buttons are at the bottom of the DRU property view:
• Delete - deletes the DRU
•  Data Set Analysis - brings up a property view that 
shows how well each variable behaves over up to 15 data 
sets, or how up to 15 variables perform against observed 
plant data for any particular data set. To show the 
stastical accuracy of the model, this view displays:
- the absolute and percentage difference between the 
observed and predicted data
- the arithmetic average and standard deviation of 
these differences
• The property view includes both ‘Good’ and ‘Bad’ data.  
To run the analysis, select the data sets to be included in 
the analysis and either input tags or output tags. Click 
Run.
• Fresh Attachments - Refreshes the attachments to the 
utility
• Close - Closes the DRU14-35
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14-36 Data Reconciliation Utility
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ThConfiguration Tab
The Configuration tab of the Data Reconciliation Utility property 
view is comprised of the following three groups:
• Problem Formulation
• Solver Parameters and Tolerances
• Data Set Configuration
The DRU configuration tab is identical to the Optimizer 
DataRecon Configuration tab and is detailed below.
In addition, the utility produces a diagnostic file: Diagnostic 
Print Level can be set to levels of None, through to Downpour 
(no diagnostic through to full diagnostics) using the drop-down 
list.
Problem Formulation Group
This group defines the main user-controls to be supplied with 
data to fit the parameter and/or measured data offsets. In the 
Fitting column, the parameter fitting can be switched off or on 
using the Mode cell.
Problem 
Formulation
Description
Perform 
Calculations
These checkboxes indicate which calculations are being 
performed.
Mode The options for Fitting are Offset Only or Fit Params. The 
options for Gross Error Detection are Full or Shortcut.
Run After A N counter that allows the DRU model to be exercised to 
only perform the fit calculations every N-th time. This 
allows the associated measurement data blocks to gather 
the historical data without full recalculation being 
performed for each new data set. If required, the counter 
can be set to 1. 
If the DRU model has a Run After N value set, it 
only runs every N-th time, allowing the data 
blocks to build up the historical data for the 
actual fitting calculations. This allows the 
historical data to be stored before the fitting 
calculations are performed.
Current This indicates the current number of runs related to the 
Run After.14-36
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ThGross Error Detection and Bad Data Elimination
Bad data elimination is specified by selecting the Gross Error 
Detection:Perform Calculations flag. This selection assumes that 
the DRU is configured with the offset data blocks that 
correspond to the measurements that are available for 
elimination.
The Mode indicates whether Full fitting is performed, or if a 
Shortcut (single) data set is used. The single data set mode 
uses the first good set, and does not fit parameters defined in 
the DRU Parameter Fit tab. The purpose of this mode is to 
provide a quick method of determining bad data within a single 
set based on the associated model.
After the DRU is run with these settings, the results are 
displayed on the Results tab. No. of Eliminations shows how 
many data blocks are eliminated in the given problem, and Max 
Eliminations shows how many accepted eliminations are 
allowed before the fitting cannot be exercised further.
The confidence is similar to that for the standard fitting, in that 
it is used to calculate the Maximum x2 to determine whether a 
good fit was achieved. The Fit Error (Total) is compared to the 
maximum tolerance to give the Goodness of Fit flag. The 
tolerance figure is based on a x2 distribution for the offsets only, 
expecting a good fit to have small offsets close to zero value.
The fitting calculation is always performed when the elimination 
model is run.
Confidence The Confidence can be set to determine the level of fit 
required for a good result. The higher the confidence, the 
closer the fit needs to be to a normalized curve for the fit to 
be deemed good.
Maximum Allows you to enter a maximum number of iterations (error 
function gradient evaluations, i.e., optimizer moves) for 
calculating the optimal parameters.
Problem 
Formulation
Description14-37
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14-38 Data Reconciliation Utility
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ThData Set Configuration Group
The Data Set Configuration allows you to configure the 
minimum, maximum, and current Data Sets.
Solver Parameters & Tolerances Group
The DRU tolerances can be user defined using the Data 
Reconciliation Utility property view. If tolerances are not 
defined, default values (generated/set by the optimization 
algorithm) are used. You can select between the MDC and MSL 
solver methods. The MDC solver parameters and tolerances that 
are available are described below. 
Data Set Description
Minimum Data 
Sets
The minimum number of good data sets required for an 
DRU calculation. A good data set is one that is not 
excluded at the start of the DRU calculation.
Maximum Data 
Sets
The maximum number of historical data sets to be 
stored locally during the estimation, but not necessarily 
all used. You can set this to store as many time-slices 
of information, although the upper limit is 32.
Current Data 
Sets
The number of data sets in the parameter estimation 
problem.Eventually, after a sufficient number of DRU 
runs this number is equal to the Maximum Data Sets 
parameter.
Horizon The measurement horizon for the data. This gives the 
number of most-recent data sets to be used in the DRU, 
out of the Maximum Data Sets stored.
In order to use the MDC Estim solver, you must have a 
HYSYS.RTO license.14-38
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Utilities 14-39
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ThParameters & 
Tolerances
Description
Central & 
Forward 
Differences
Intervals that are used to determine the perturbation 
in the parameters / offset used for the calculation of 
the (error function) objective gradients with respect to 
the variables. If these values are not set, the 
optimization routine uses additional model evaluations 
to determine the values to be used.
Optimality 
Tolerance
The smallest relative change in the total error function 
during the error minimization below which the 
optimization is deemed to have converged by the 
algorithm.
Linesearch Tolerance that is used by the optimization routine to 
determine the accuracy of the optimal step with 
respect to the gradient evaluations. The larger the 
Linesearch tolerance, the further along the optimal 
path the next optimal step will be. This number must 
be between zero and one.
Maximum Step Determines how far each of the variables (parameters, 
offsets) can be moved in an optimal step. This 
prevents the optimizer from overstepping on each 
iteration, thus speeding up the solution.
Objective Scaling Allows the emphasis between offset and parameter 
fitting to be varied when both offsets and parameters 
are fitted simultaneously. The emphasis is squared 
based on the given number; a function scale factor of 
10 places 100 times more emphasis on the elimination 
of measured / model error than on fitting the offsets.
Convergence 
Tolerance
The smallest change to occur to every parameter/
offset below which the minimization is deemed to have 
converged.
Default 
Responses
If the checkbox is selected, the DRU automatically 
answers “Yes” if there are datasheets that need to be 
removed. It also answers “No” to the query about 
whether the DRU should start solving from the last 
parameter result value. It uses the Start value instead.14-39
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14-40 Data Reconciliation Utility
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ThIf the MSL solver method is selected, the Gross Error Detection 
and Data Elimination options are not available for the Problem 
Formulation group. The following figure shows the parameters 
and tolerances that the MSL method uses for the DRU. 
The MSL solver parameters and tolerances are described below. 
 Figure 14.24
MSL Parameters & Tol Description
Forward Difference (FD) Interval used to calculate the perturbations 
for calculating the Jacobian matrix. FD high or 
FD low is used. If neither high or low methods 
are used, by default, they are set to 
0.9*current value and 1.1*current value, 
respectively. Jacobian steps are always 
forward, for example, if the last step caused 
an increase in a variable then the jacobian 
calculation steps will also be in the same 
direction.
Reset Perts It is recommended to have this option 
selected. All Jacobian perturbations are 
calculated from the same point ensuring a 
more accurate Jacobian. Although, this 
increases the solve time.14-40
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Utilities 14-41
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ThThe Maximum Iteration Limit determines the maximum number 
of iterations allowed to the optimizer to generate its optimal 
solution. Generally, after approximately five iterations, the 
optimizer is close enough to the fitting solution to be terminated 
with confidence. This is because the optimization problem is 
unconstrained, the only limits are imposed from the parameters.
LMDer Data Check The Data Check is only used when the LMDer 
Solver Method is selected. It assesses the 
data sets to see if any of them are out of sync 
(possibly a bad data set). DRU prompts the 
user if these sets need to be removed. The 
results of the sets that are removed are 
displayed on the Info page of the DCS tags 
tab. 
Solver Method The MSL solver allows you to select from the 
LMDer (used in Sim Adjusts) and the NS23 
(HSL method) methods. 
• LMDer - The Levenberg-Marquardt 
algorithm that solves equations by 
minimizing the sum of squares of the 
residuals on the right hand side. 
Levenberg-Marquardt is thus a 
specialized optimization function for 
least squares.
• NS13 - This solver is intended for large, 
sparse systems. 
It is recommended to use the LMDer, 
although the NS23 may prove to be better in 
some situations.
MSL Parameters & Tol Description14-41
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14-42 Data Reconciliation Utility
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ThResults Tab
The updating routine produces a set of results that can be seen 
on the Results tab . The Results tab is displayed based on the 
MDC solver method. 
 Figure 14.25
If the MSL solver is selected, only relevant parameters are 
displayed.14-42
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Utilities 14-43
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ThThe Parameter Fitting results are described below.
A summary of the user-supplied parameters is also supplied in 
the Number Of group.
Parameter/Offsets
These are the most important results obtained from the 
updating. They define the parameters which most accurately 
describe the actual plant for the data given in the model input 
and output blocks.
The parameter results can be viewed on the Parameter Fit tab.
Parameter Fitting Description
Chi2
Maximum Chi2
The value of x2 gives the x2 calculation based on 
the sum of the data block errors scaled by the 
sigma, s, for each of the output data blocks. This 
value is then checked against the maximum x2 
value (Maximum Chi2), which is calculated from 
the stated confidence and the calculated number 
of degrees of freedom (Degrees of Freedom) for 
the problem. If the calculated x2 value is less than 
the maximum value, the Fit flag is deemed good, 
and the parameters and offsets are updated. A 
bad fit leaves the parameters and offsets with 
their original values. 
Goodness of Fit The Goodness of Fit returns whether a good or bad 
fit was returned by the x2-test. Major Iterations 
indicates the number of parameter variation steps 
undertaken by the optimization algorithm with 
minimizing the total error.
Fit Error (Total) The Fit Error (Total) gives the total sum of errors 
for all datablocks of each good historical data-set. 
The sum is between the measured values and the 
model calculated values, the error being calculated 
using the final value of the predicted parameters 
and measurement offsets.
Starting Objective
Final Objective
The change in objective function can be seen by 
comparing the Starting Objective to Final 
Objective. The objective quoted is the actual 
objective seen by the optimization routine, and is 
based on the scaled offsets and error functions.
Function Calls The value for Function Calls indicates how many 
times the plant model was executed by the 
updating algorithm in arriving at the fit answer.
Major Iterations The value indicates how many times the objective 
function has been evaluated by the optimizer.14-43
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14-44 Data Reconciliation Utility
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ThThe calculated offsets can be seen by examining the individual 
data blocks on the DCS Tags tab as shown in the next section.
In most cases, successive updating over time should result in a 
progressively more accurate solution.
Stream Initialization Tab
Figure 14.26 shows the Stream Initialization tab. This indicates 
the connections from the estimated entries in the plant model to 
the measurement data list that contains the input and the 
output measurement data blocks. The screen identifies whether 
a measurement data block is a model input or calculated result.
This form displays information concerning flowsheet model inlet 
/ outlet streams, energy streams, and internal streams. An inlet 
stream is a stream in the model that is an inlet to a reconciled 
unit operation (targeted using the Target Objects button), but 
not an outlet. An outlet stream is an outlet to a reconciled unit 
operation, but not an inlet.
 Figure 14.2614-44
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Utilities 14-45
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ThEnergy stream refers to the standard HYSYS energy streams. 
Internal streams are both inlet and outlet streams (i.e., are both 
feeds and products to unit operations), or are either feeds or 
products to a unit operation which is not reconciled. The 
initialization prior to carrying out a run of the estimation is done 
using DRU streams, streams created by you specially for the 
purpose of storing simulated plant data in flowsheet streams; 
the DRU streams are effectively storage mechanisms. The 
Multiple flag column indicates whether historical data is 
available for the flowsheet stream, data which is stored in the 
DRU object; if unchecked, any specified values of the 
corresponding flowsheet stream are held constant for the 
duration of the parameter estimation.
The Data Sets column indicates the number of data sets 
available for each stream kind. The Comp Basis column 
represents the basis for the component calculation in each 
stream.
Parameter Fit Tab
The model parameters can be accessed from the Parameter Fit 
tab of the Data Reconciliation Utility property view. 
 Figure 14.2714-45
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14-46 Data Reconciliation Utility
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ThThese parameters are adjusted to give the best fit for the model 
to the data given in the output blocks. For example, the 
efficiency of a heat exchanger or the reaction coefficients of a 
reactor model.
The Start and Current values show the values of the parameters 
before and after an update was carried out. After an update, and 
only if the fit is good, the new values are placed directly into the 
model. The Result Value stores the value of the parameter after 
the last run of the DRU. The Hooked Object/Variable refer to the 
object and property in the flowsheet model which is estimated. 
The Fit allows you to turn on/off the fitting parameters.
The Minimum and Maximum values define the range over which 
the parameters are allowed to vary. These values should be 
considered carefully so as not to constrain the model to a region 
in which the model solution is greatly different from the actual 
plant. The range is also used in calculating the Jacobian set-size.
DCS Tags Tab
The DCS Tags tab is used for defining the transfer of measured 
data to the flowsheet model during the DRU calculations.
 Figure 14.2814-46
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Utilities 14-47
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ThThe Tag Filter group has options to display model Input data, 
Output data, or All data (input and output), depending on the 
radio button selected. Input data consists of property values of 
streams that are read in the model, but are not reconciled. 
Output data, consisting of property values, are then reconciled 
to these (read) values by the parameter estimation algorithms 
in the DRU.
If MSL is the solving method selected, the Low Limit parameter 
is added and all other non-applicable parameters are removed.
The following table shows a quick outline on the parameters you 
may encounter when setting up the DCS Tag Set-up. These 
parameters are detailed in earlier sections. 
Parameters Description
Property Allows you to enter a name for the tag. Click the tag 
name to view the DCS tag properties/connections.
Current Value Value of the parameter in the flowsheet.
Scale This scales errors for the Objective Function.
Offset Bias/offset calculated by DRU or can be specified by 
the user.
Limit The upper limit on the tag.
Low Limit The lower limit on the tag.
Total Error The error between the measured data and HYSYS data.
Calculate Bias Calculates a bias for the tag.
Use Bias Allows you to use a specified/calculated bias in the 
calculation.
Input A tag that is used as an input variable.14-47
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14-48 Data Reconciliation Utility
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Th14.7.2 Optimization Objects
An DRU stream and DCS Tags are considered to be Optimization 
Objects. These optimization objects are input tags or output 
tags, corresponding to input or output data from the model. 
These objects can be accessed by selecting Optimization Objects 
from the Flowsheet menu on the desktop. A given optimization 
object can be edited by highlighting it and clicking the Edit 
button on the Select Optimization Object property view.
The Optimization Object property view for the selected object 
displays. There are three tabs in this property view: 
• Connection
• Properties
• Transfer
These tabs are described in the following sections.
 Figure 14.2914-48
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Utilities 14-49
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ThConnection Tab
The Connection tab gives the connections of an optimization 
object to the flowsheet Object name. The connection in this case 
is DCS tag to the Mass Flow of the Feed.
Properties Tab
The second tab lists the Properties of an optimization object.
 Figure 14.30
 Figure 14.3114-49
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14-50 Data Reconciliation Utility
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ThThe myvarval property (“my variable value”) stores the value of 
the connected object property. The scale value is used to scale 
the measured values, and hence the (measured - model) error, 
to ensure the optimizer objective function sees the errors with 
required weightings. Generally, the scaling should be selected so 
that the relative values for each of the errors on the model 
outputs is approximately equal. This ensures the optimizer 
selects a fair set of parameters and/or offsets to fit equally on 
the measured outputs.
If an output is to be favoured, its scaling should be smaller so 
the relative error is larger, forcing the optimizer to correct that 
error over the other errors. For offset fitting, the scaling is 
important for both input and output blocks since the offset is 
scaled by this amount for the objective function. For output 
blocks the scaling is also used to calculate the relative error 
between the measured and model values, so offset is scaled the 
same as the error. 
To counter this, the DRU tolerances allow the overall offset 
portion of the objective function to be scaled differently to the 
error portion, thus enabling preference of fitting for either 
offsets or parameters. When parameter fitting only, the scaling 
is only relevant to the output blocks where it is used to scale the 
absolute error to a relative error.
The offset value indicates the absolute offset to be applied to the 
measure values; this can be a fixed, known amount, or an offset 
calculated by the fitting algorithm. The exact use is determined 
by the set-up flags in the data block. For offset fitting, there are 
no minimum and maximum limits since the optimizer is 
attempting to minimize the value of the offsets, and thus be 
driving them to zero.14-50
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Utilities 14-51
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ThThe error property stores the calculated error between the fitted 
model data and the actual measured data, for a given data set. 
The sigma property is an estimate of the true asymptotic 
standard deviations of the measured value from the plant. The 
estimate is updated at each run of the DRU in such a way it 
causes it to asymptotically approach the correct value for the 
instrument. The update takes account of the current value of 
sigma, and weighting which takes into account the previous 
estimate. The initial value of sigma selected is typically large 
(~1000), to provide a good initial fit. Sigma is only calculated 
for output data blocks (Output Tags).
The value of sigma is used to calculate the goodness of fit; the 
scaled error between model calculated value and the measured 
value is divided by the sigma value to determine the effect of 
the data block in the overall x2 fit calculations. The smaller the 
value, the smaller the error allowed to maintain a good fit. 
Where the sigma is not reset on each run, the closer the 
measured value is to the model value, the smaller the calculated 
sigma is for use in the cumulative sigma update. As this is 
calculated cumulatively, it tends to its natural sigma value. It 
should be noted that the sigma value is only used for the 
goodness of fit calculations, and plays no part in the actual 
fitting optimization.
The next_value property is the value most recently assigned to 
the given tag (i.e., as if it were read in from a DCS system).
The remaining properties have no unit dependency on the 
connection:
• Count. Number of measured value updates to the DCS 
Tag since the last estimation run.
• Totcount. Total number of measured value updates.
• Calc_bias. Used to tell the algorithm that the data block 
is to be included in the offset fitting set, and thus the 
offset is adjusted to attempt to minimize the measured/
model error. If the data-block is set to calculate offsets, 
then it is also included in the bad data elimination 
algorithm.
• Over_data. Not currently used in the DRU.
• Next_good. Stores whether the next value (obtained 
from the use in the offline case, or from a DCS system in 
the on-line case) is considered good or bad data.14-51
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14-52 Data Reconciliation Utility
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Th• Input. Indicates if the variable is an input to the model 
or not.
• Use_bias. Set by the user if you want to use the current 
biases during model runs, not the updated ones, if they 
are calculated. The flag tells the algorithm that a fixed, 
known offset is to be applied to each set of measured 
data for use in the generation of measure/model error. In 
this case, the offset value is not calculated, and the data 
block is not included for elimination in the bad data 
elimination algorithm.
• Fill. Reserved for future use.
• Eliminated. Returned as a result from the bad data 
elimination algorithm to indicate that the data set is 
deemed bad. In this case, the offset is removed from the 
objective function and allowed to “float”. The resultant 
model calculated value is then available from the 
myvarval field. The flag can also be used during normal 
offset fitting to determine a model calculated value 
without restricting the offset in the normal optimization 
objective function.
• Curval, and curerror. Indicates the current value and 
error of the object in the calculation.
Transfer Tab
The Transfer tab lists the Transfer flags of an optimization 
object. These flag properties are not used in the offline 
situation.
 Figure 14.3214-52
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Utilities 14-53
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Th14.7.3 DRU Diagnostic File 
Output
The following section details the diagnostics available from DRU 
and the associated optimization routine.
There are three sections produced in the diagnostic output from 
an DRU run. These sections are covered separately. In addition, 
several levels of output are available, based on the level 
selected within the DRU. The descriptions below deal with 
diagnostics produced when the Downpour diagnostic option is 
selected. All output produced is generated by the optimization 
routines; MDC Technology Ltd. do not currently supply 
additional output from the DRU routine.
The name of the diagnostic file produced by the DRU is of the 
form .txt, where  is the name of your 
DRU object in HYSYS.
Initial Problem Parameters
The first section of output produced by the optimization routine 
details the input parameters for the particular problem to be 
solved. These are either supplied as a result of the problem, or 
are defaults used by the algorithm. Since the application of the 
optimizer to the DRU task is an unconstrained problem, several 
of the parameters and variables produced as part of the output 
are not relevant to the task and should be ignored.
• Linear constraints. Number of linear constraints in the 
problem. This is not applicable for DRU.
• Linear feasibility. Maximum acceptable violation of 
linear constraints at a feasible point. This is not 
applicable for DRU.
• Variables. Number of variables (parameters or offsets) 
to be optimized (fitted) in the current problem.
• Crash tolerance. Used when COLD start is selected. 
Variables within this tolerance of their bounds are 
selected for the initial working set of the problem.
• Infinite bound size. Any bound greater/less than this 
number is considered +/- .∞14-53
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14-54 Data Reconciliation Utility
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Th• COLD start. Specifies the initial working set for the 
problem. This is selected from the initial value of the 
variables, including variables at, near, or just violating 
their bounds.
• Infinite step size. Magnitude of a change in the 
variables that would indicate an unbounded problem (the 
objective is said to be unbounded in the feasible region). 
Since DRU variables are all bounded between -1 and +1, 
this parameter is not relevant to an DRU task.
• EPS (machine precision). The machine precision, used 
to determine the default values for several other 
parameters.
• Step limit. The maximum change in a variable on the 
first step of the linesearch. This prevents overflow 
situations from occurring.
• Nonlinear constraints. The number of non-linear 
constraints. This is not applicable for DRU problems.
• Nonlinear feasibility. The maximum acceptable 
violation of non-linear constraints at a feasible point. This 
is not applicable for DRU problems.
• Nonlinear objective vars. Number of (non-linear) 
variables used to minimize the objective function.
• Optimality tolerance. The accuracy of the final iterate 
to approximate a solution to the problem, i.e. a solution 
is deemed valid if the relative change in the objective 
function is less than this tolerance. In effect, this value 
indicates the number of correct figures required in the 
objective function at solution (i.e. if the tolerance is 10-6 
and the optimization terminated successfully, 
approximately the first six figures of the objective 
function are correct. This is an indication of the 
“tightness” of the problem solution.
• Nonlinear Jacobian vars. The number of variables 
used to evaluate the Jacobian matrix of the problem.
• Linesearch tolerance. The accuracy of the step taken 
during each iteration to approximate a minimum of the 
merit function along the search direction. This 
determines how far along the search path the next point 
is to be taken.
• Derivative level. This indicates how many of the 
objective (and constraint) gradients are supplied to the 
algorithm. DRU uses the algorithm with a level of 0, 
which indicates that all gradients are not supplied, and 
have to be calculated using difference approximations.
• Function precision. The accuracy with which functions 
are assumed to be evaluated.14-54
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Utilities 14-55
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Th• Verify level. A value of zero indicates that the 
optimization routine performs a 'cheap' finite-difference 
test on the objective gradient components of the 
problem. This is not applicable for DRU (where no 
gradients are supplied).
• Major iterations limit. The maximum number of major 
iterations performed before the problem is terminated 
(unsuccessfully).
• Major print level. Determines the output level on each 
major iteration.
• Minor iterations limit. The maximum number of 
iterations used to calculate the optimality of the QP 
subproblem.
• Minor print level. Determines the output level on each 
minor iteration.
• Difference interval. The interval used in the forward 
difference approximation for the objective gradients in 
the Jacobian matrix.
• Central difference interval. The interval used in the 
central difference approximation for the objective 
gradients in the Jacobian matrix. Central difference 
approximations are used if the forward difference 
approximations are found to be not accurate enough.
• JTJ initial Hessian. Controls the initial value of the 
upper triangular matrix R (the estimate of the 
transformed and re-ordered Hessian of the Lagrangian). 
J is the objective Jacobian matrix.
• Reset frequency. The number of major iterations after 
which the Hessian is reset to JTJ.
In addition to the above parameters, the work arrays are 
checked for suitable sizing, and a summary of the Jacobian 
element estimations is given.14-55
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14-56 Data Reconciliation Utility
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ThIteration Output
On each major iteration, output is generated to detail the 
progress of the optimization algorithm in minimizing the DRU 
function. The output for each iteration is given under the 
iteration header, Major iteration n. The following list details the 
tabulated output produced; the heading is only produced for the 
first iteration.
• Itn. The major iteration count.
• ItQP. The sum of the iterations required by the feasibility 
and optimality phases of the QP problem (which 
generates the optimal step direction and length). Large 
values indicate difficulty in finding a new optimal point.
• Step. The step, , taken along the computed search 
path. On a reasonably behaved problem, this tends to 
unity.
• Nfun. The cumulative number of subfunctions needed for 
the linesearch (excluding finite difference calculations). 
This provides a guide on the amount of work performed 
in the linesearch.
• Objective. This is the value of the objective function, 
which should decrease monotonically as the optimization 
progresses. This should not be confused with the 
objective function calculated upon termination of the 
DRU task. This value is also repeated after the table 
(with more significant figures).
• Bnd. The number of simple bound constraints in the 
predicted active set. This is not applicable for the DRU 
task, and is always zero (after the first iteration).
• Lin The number of linear constraints in the predicted 
active set. This is not applicable for the DRU task, and is 
always zero.
• Nz. The number of variables less the number of 
constraints in the predicted active set. For an DRU task 
this is always the number of parameters or offsets being 
fitted.
• Norm Gf. The Euclidean norm of the gradients of the 
objective function with respect to the free (unbounded) 
variables.
• Norm Gz. The Euclidean norm of the projected gradient. 
This is approximately zero near the solution.
• Cond H. The lower bound on the condition number of the 
Hessian approximation, H.
• Cond Hz. The lower bound on the condition number of 
the projected Hessian approximation, Hz. The larger this 
number is, the more difficult the problem is to minimize.
α
14-56
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Th• Cond T. The lower bound on the condition number of the 
matrix of predicted active constraints. This is not 
relevant to the DRU application.
• Conv. This is a three letter indication of the convergence 
test status. The letters indicate True or False. The letters 
detail the following points, in order:
- sequence of iterates has converged
- projected gradient (Norm Gz) is sufficiently small
- constraint residual norm in the active set (Norm C) is 
sufficiently small (this is always true in the DRU 
application)
The following letters may display at the end of an output line:
For each major iteration, a section is produced detailing the 
“Values of the constraints and their predicted status”. The 
variables are listed in order, giving the value of the scaled 
variable (which is scaled internal to the optimization routine 
between -1 and +1), and its predicted status.
For instance, if a parameter is allowed to vary in the model 
between 0 and 100, and lies at the model value of 25, the scaled 
value internal to the optimization routine would be -0.5. The 
predicted status is a binary number, zero indicating the variable 
is free, and one indicating the variable is at one of its bounds.
Also produced are the diagonals of R, which are the 
triangulation factors of the transformed and re-ordered Hessian.
Letter Description
C Indicates the use of central difference approximation in the 
gradient evaluations.
L Indicates that the linesearch produced a change in a variable 
greater than specified by STEP LIMIT.
R Indicates that refactorization of the approximated Hessian is 
performed.14-57
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14-58 Data Reconciliation Utility
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Th Final Output
Upon termination of the optimization algorithm, whether 
successful or not, the final output is produced. The number of 
subfunction calls made by the optimization routine differs from 
that made by the DRU task, since DRU evaluates the 
subfunction outside of the optimization routine as part of its 
solution. The following details are written as final output from 
the optimization algorithm.
• INFORM. This details the status of the algorithm 
solution. Zero indicates successful solution.
• MAJITS. The number of major iterations performed.
• NFUN. The total number of function evaluations 
performed during the optimization (excluding those 
needed for gradient estimations).
• NGRAD. The number of function evaluations performed 
for gradient estimations.
• Varbl. The name (V) and the index of the variable.
• Value. The scaled value of variable V.
• State. The status of the variable. FR indicates the 
variable is unbounded, LL indicates the variable is 
bounded at its lower limit, and UL indicates the variable 
is bounded at its upper limit.
• Lower Bound. This is the value of the lower bound for 
the variable within the optimization routine. For DRU 
tasks this is always -1.
• Upper Bound. This is the value of the upper bound for 
the variable within the optimization routine. For DRU 
tasks this is always +1.
• Lagr Mult. This gives the Lagrangian multiplier of the 
variable, if the variable is bounded. The value is zero for 
a free variable, positive for a variable at its lower limit, 
and negative for a variable at its upper limit.
• Residual. This is the difference between the variable 
and its NEAREST bound.
The optimization routine termination code is printed and the 
final value of the (internal) objective function is displayed as the 
last output (this is not the same as displayed by DRU, since the 
optimization value is internally scaled).14-58
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Th14.8 Derivative Utility
The Derivative utility is a component of the HYSYS.RTO real-
time optimization package available as a plug-in to the basic 
HYSYS software package. The Derivative utility is one of two 
utilities used by HYSYS.RTO to provide the primary interface 
between the flowsheet model and the solver. Their primary 
purpose is to collect appropriate optimization objects, which are 
then exposed to solvers to meet a defined solution criteria. 
Refer to the Aspen RTO Reference Guide for details 
concerning the use of this utility. This guide details all features 
and components related to the HYSYS real time optimization 
package.
If your current HYSYS version does not support RTO, contact 
your local AspenTech representative for more details.
To add the Derivative 
utility, refer to the 
section on Adding a 
Utility.14-59
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14-60 Dynamic Depressuring
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Th14.9 Dynamic 
Depressuring
In the process design of safe pressure relief systems9, a 
depressurization process reduces the pressure and the 
inventory of pressurized vessels. HYSYS Dynamic Depressuring 
Utility uses a rigorous dynamic model for the depressurizing 
process, allowing you to accurately capture the dynamic 
behavior of depressuring operations. 
To start the Dynamic Depressuring calculations, specify enough 
information in the utility, and click the Run button on the 
Dynamic Depressuring property view. If you want to stop the 
utility while it is calculating, click the Stop button.
 Figure 14.33
The dynamic depressuring utility does not require dynamics 
or other additional special licenses to run.14-60
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Utilities 14-61
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ThThe entered data gets transferred to a subflowsheet of the 
depressuring system (one inlet stream and one vessel). 
It is this subflowsheet that is run in dynamics until the 
depressuring time is complete, and the system then returns to 
steady state. The results are retrieved from the strip charts, and 
displayed on the Performance tab.
Dynamic Depressuring Subflowsheet
The dynamic depressuring subflowsheet is not meant to be 
altered in any way. In fact, before the utility runs, HYSYS checks 
to see if the template has been changed (for example, if the 
number of streams and unit operations has change), and if it 
has been changed HYSYS deletes the altered subflowsheet and 
creates a new one.
There are three spreadsheets in the subflowsheet:
• vapour flow rate
• liquid flow rate
• duty
 Figure 14.34
The Dynamic Depressuring utility works with any fluid 
package, except for the electrolyte fluid package and where 
solids are present.
To add the Dynamic 
Depressuring utility, 
refer to the section on 
Adding a Utility.14-61
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14-62 Dynamic Depressuring
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ThThe three spreadsheets are used for the flow rate and heat flux 
equations. The calculated flows are exported from the 
spreadsheets to either the vapour, liquid, or duty stream flow.
The Dynamic Depressuring utility provides an Use 
Spreadsheet option for both the liquid and vapour flow rate, 
and the heat flux equation. The Use Spreadsheet option gives 
unlimited possibilities of flow rate and heat flux equations. 
You can select the Use Spreadsheet option from the Operating 
Mode drop-down list on the Heat Flux page of the Design tab 
in the Dynamic Depressuring utility property view. When you 
select the Use Spreadsheet option, a View Spreadsheet button 
appears. By clicking the View Spreadsheet button, the 
corresponding spreadsheet opens to be modified.
The flow rate spreadsheets are not always used. When a fisher 
valve or a relief valve is selected the standard unit operation is 
added to the subflowsheet. 
When the utility runs, the values of the variables for the 
selected equation are transferred to the spreadsheet.
The spreadsheets are used to transfer data from the utility, 
which is manipulated and then sent to different unit 
operations. As a result the spreadsheet is being over written 
every time the utility runs. 
If you modify the spreadsheet and run the utility, your added 
information is lost. The only time a spreadsheet is not 
overwritten is when the Use Spreadsheet option/mode is 
selected.
For more information 
regarding the equations 
that are used when 
either the fisher valve or 
relief valve is selected, 
refer to the section on 
Choosing the Valve 
Equation.14-62
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Utilities 14-63
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ThOperation Modes
The operation modes available in the Dynamic Depressuring 
operation are as follows: 
• Fire
• Fire Stephan Boltzman
• Fire API521
• Adiabatic
• Use Spreadsheet
You can view the results of the depressuring calculations in 
either tabular or graphical format.
The four types of depressuring calculations available are as 
follows:
The only time the values specified in a spreadsheet is not 
overwritten is when the Use Spreadsheet mode is selected.
Calculation Description
Fire Mode Used to simulate plant emergency conditions that 
occur during a plant fire. Pressure, temperature, and 
flow profiles are calculated for the application of an 
external heat source to a vessel, piping, or 
combination of items. Heat flux into the fluid is user 
defined. Do not specify a wetted area for this 
calculation.
Fire Stephan 
Boltzman
This mode includes radiation term, forced convection 
term, flame temperature, and ambient temperature 
term in the calculation.
Fire API521 The same as Fire Mode except the heat flux into the 
fluid is calculated from the API equations for a fire to a 
liquid containing vessel. A wetted area for the vessel is 
required, and is used for heat transfer in the model.14-63
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14-64 Dynamic Depressuring
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ThThe Dynamic Depressuring utility can be used to simulate the 
depressuring of gas, gas-liquid filled vessels, pipelines, and 
systems with depressuring through a single valve. References to 
“vessel” can also be “piping” or “combinations of the two.”
14.9.1 Design Tab
The Design tab contains the following pages: 
• Connections
• Config. Strip Charts
• Heat Flux
• Valve Parameters
• Options
• Operating Conditions
• Notes
Adiabatic Used to model the gas blow down of pressure vessels 
or piping. No external heat is applied. Heat flux 
between the vessel wall and the fluid is modeled as the 
fluid temperature drops due to the depressurization.
The heat transfer coefficient is entered by the user, or 
can be calculated by HYSYS from the vessel fluid’s 
vapour properties.
When estimated by HYSYS, the heat transfer 
coefficient is estimated from the “wetted” area and the 
vessel volume specified by the user. The “wetted area” 
specified should be equal to the total surface area of 
the vessel, not the area in contact with the liquid.
Typical use of this mode is the depressuring of 
compressor loops on emergency shutdown.
Use Spreadsheet If you change the mode from Use Spreadsheet to 
another mode, the spreadsheet is over written.
Calculation Description
Refer to Dynamic 
Depressuring 
Subflowsheet for more 
information on the Use 
Spreadsheet mode.14-64
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Utilities 14-65
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ThConnections Page
The Connections page allows you to specify the inlet stream, 
vessel volume, and initial liquid volume for the utility. 
• Name field enables you to change the name of the 
dynamic depressuring utility.
• Inlets row enables you to enter or select up to four inlet 
streams for the utility.
• In the Vessel Parameters group, you can select the 
vessel’s orientation using one of Orientation radio 
buttons (Horizontal or Vertical), and you can change the 
vessel surface area of the head for heat transfer 
calculations in the Heat Transfer Areas table.
The parameters in the Correction Factors table are used 
to consider effects of the metal mass in contact with the 
liquid, and the metal mass in contact with the vapour.
If you enter only one inlet stream in the Vessel Parameters 
group, you must enter a volume for the vessel, liquid volume, 
and the height or diameter of the vessel; or enter the liquid 
volume, height, and diameter of the vessel. HYSYS then 
calculates the missing information.
 Figure 14.35
Each stream has its own vessel volume and liquid volume.14-65
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14-66 Dynamic Depressuring
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ThIf you enter more than one inlet stream, two rows appear 
underneath the Inlet row. The two rows are Vessel Volume and 
Liquid Volume. You can enter the vessel volume and the liquid 
volume for each stream in the associated Vessel Volume and 
Liquid Volume fields. Default values of the vessel parameters are 
calculated using a settle out calculation.
The vessel/liquid volume fields are available for each inlet 
stream specified, and the fields are described in the section 
below.
Vessel\Liquid Volume Fields
For the stream selected for depressuring, HYSYS requires the 
vessel volume and the normal expected liquid volume of the 
vessel (in other words, at the normal liquid level). If the feed 
stream is two phase, the composition of the liquid is calculated 
from this.
You must either specify the Height and Diameter, or the Flat End 
Vessel Volume. If you specify only the Flat End Vessel Volume, 
HYSYS automatically estimates the Height, Diameter, and Initial 
Liquid Volume. By specifying only the vessel volume, the liquid 
volume is calculated using Equation (14.5) and the remainder 
of the vessel is assumed to be filled with equilibrium vapour.
For more than one stream, a settle out calculation is done. 
The results are approximate, because the settle out 
calculation is used in one vessel (like the Original 
Depressuring utility). 
Larger systems and more complex configurations can be 
studied in Dynamics mode, where the pipe networks and so 
forth, can be configured.
(14.5)
The Liquid Volume must be greater than 0 and less than the 
Flat End Vessel Volume.
Liquid Volume Liquid Volume Flow of Liquid Phase 1×  hour=14-66
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Utilities 14-67
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ThIf you specify both the Initial Liquid Volume and Flat End Vessel 
Volume, then the head space is assumed to be filled with 
equilibrium vapour.
Config. Strip Charts Page
The Config. Strip Charts page allows you to add, modify, or 
delete strip charts, and select the variables you want to appear 
in each strip chart. 
 Figure 14.36
You don’t have to create a strip chart, because the dynamic 
depressuring utility automatically creates a minimum 
required variable strip chart.
When creating additional strip charts, ensure the select 
variables are from the correct depressuring subflowsheet.14-67
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14-68 Dynamic Depressuring
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ThThe table below describes the objects available on the Config. 
Strip Charts page:
Object Description
Logger Name 
field
The name of the selected strip chart on the list. You 
can change the name of the strip chart, by entering a 
new name in this field.
Sample Interval 
field
The length of time between data samples taken for the 
strip chart. The sample interval is set to equal the time 
step size specified on the Operating Conditions page of 
the Design tab.
You have to run the Dynamic Depressuring utility 
calculations after the strip chart has been changed, or 
created in order to view the updated strip chart.
List The list on the left side of the Logger Name field 
contains all the names of the strip charts associated 
with the current dynamic depressuring utility. You can 
manipulate the variables of strip charts by selecting 
the name of the strip chart on the list.
Table Contains all the variables that can be stored in the strip 
chart. You can select, which variable you want to be 
stored in the strip chart during calculations by selecting 
the checkbox associated with the variable.
Create Plot 
button
Allows you to create a new strip chart. Click this button 
and a new strip chart appears in the list. The default 
name of the new strip chart is DataLogger.
Delete Plot 
button
Allows you to delete strip charts. Select the strip chart 
you want to delete from the list and click this button. 
This button is only available if there is a strip chart in 
the list.
Add Variable 
button
Allows you to enter a new variable in the strip chart. 
Select the strip chart you want the variable to appear 
in and click this button. The Variable Navigator 
property view appears, and you can select the variable 
you want to add from this property view.
View Strip Chart 
button
Allows you to view the strip chart. Select the strip chart 
you want to view from the list and click this button, the 
strip chart property view appears.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.14-68
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Utilities 14-69
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ThHeat Flux Page
On the Heat Flux page, you can specify the depressuring mode 
and heat loss model for the utility.
View Historical 
Data button
Allows you to view the data points stored in the strip 
chart in table format. Select the strip chart you want to 
view from the list and click this button, the Historical 
Data property view appears.
The Historical Data property view contains two buttons 
that allow you to save/export the results:
• Save To CSV File
• Save To DMP File
Create Aspen 
Flare System 
Analyzer Plot 
button
Allows you to create a strip chart that contains 
information you may want to export to Aspen Flare 
System Analyzer. 
Click this button to create the strip chart. The default 
name is the dynamic depressuring utility’s name 
followed by FLARENET. To add another FLARENET strip 
chart, change the default name of the previously 
created FLARENET strip chart before clicking the 
Create Aspen Flare System Analyzer Plot button again.
You have to run the Dynamic Depressuring utility 
calculations after the strip chart has been changed, or 
created in order to view the updated strip chart.
 Figure 14.37
Object Description14-69
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14-70 Dynamic Depressuring
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ThThe available choices for depressuring modes are as follows:
• Fire Mode. When depressuring in Fire mode, five 
coefficients (C1 to C5) are required to set up the 
following generalized equation:
where:  
t = Time, seconds
T = Vessel temperature, °C
Vt = Liquid volume at time = t
Vo = Liquid volume at time = 0
As an example, you can model the standard heat transfer 
equation:
By setting C1, C2, and C5 to zero. Set C3 to UA and C4 to 
the constant temperature in the  term.
• Fire API521 Mode. The Heat Flux Parameters page for 
depressuring in Fire API521mode is similar to the 
property view observed in Fire mode. 
Three coefficients C1 to C3 need to be specified to set up 
the following equation, which is an extension to the 
standard API equation for flux to a liquid-containing 
vessel.
Depending on the version of HYSYS that you used to 
build the dynamic depressuring case, the heat flux is 
calculated differently.
For HYSYS 3.1 or older version: 
(14.6)
(14.7)
The wetted area is required for the Fire API521.
(14.8)
Refer to Section  - 
Operation Modes for a 
description of the 
available modes.
Q C1 C2t C3 C4 T–( ) C5
Vt
V0
-----⎝ ⎠
⎛ ⎞+ + +=
Q UAΔT=
ΔT
Q C1 wetted area(time=t)[ ]
C2⋅=14-70
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Utilities 14-71
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ThFor current version of HYSYS:
• Fire Stephan Boltzman Mode.The following equation is 
used for the Fire Stephan Boltzman mode. This equation 
includes a radiation term, forced convection term, flame 
temperature term, and ambient temperature term.
where:  
Atotal = total surface area
 = flame emissivity
where:
(14.9)
The units of the wetted area are controlled by the 
preferences, and not by the equation units.
(14.10)
Equation (14.10) uses a more rigorous method to calculate 
the wetted area by taking into account of the orientation of 
the depressuring vessel. In HYSYS 3.2 the depressuring 
utilities automatically use Equation (14.10) to calculate the 
heat flux. For cases that are built with HYSYS 3.1 or older 
version, when you re-run the depressuring utility in HYSYS 
3.2 you have the option to calculate the heat flux using 
Equation (14.9) or Equation (14.10). However, once you 
selected Equation (14.10) and saved the case, you cannot re-
calculate the heat flux using Equation (14.9).
wetted area(time=t)
wetted area(at time=0) 1 C3 1 LiqVol(time=t)
LiqVol(time=0)
---------------------------------------––
⎩ ⎭
⎨ ⎬
⎧ ⎫
×=
Q C1 C3 wetted area(time=t)⋅[ ]
C2⋅=
(14.11)Q Atotal k( εf Tf 273.15+( )4× εv Tv 273.15+( )4× ) OutsideU Tambient Tv–( )×+–( )××=
εf14-71
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14-72 Dynamic Depressuring
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Th = vessel emissivity
k = Boltzman constant
Tf = flame temperature
Tv = vessel temperature
OutsideU = convective heat transfer coefficient between 
vessel and surrounding air
Tambient = ambient temperature
• Adiabatic Mode. When Adiabatic mode is selected, heat 
flux information is not required.
• Use Spreadsheet Mode. The Use Spreadsheet option 
refers to the duty spreadsheet of the Dynamic 
Depressuring utility used by the utility. 
This option allows you to edit the duty spreadsheet 
without the values in the spreadsheet getting overwritten 
when the utility runs. This option also allows the more 
advanced users the ability to use a different equation for 
the heat flux. 
When this option is selected, the View Spreadsheet 
button appears. Clicking the View Spreadsheet button 
opens the duty spreadsheet.
Heat Loss Parameters Group
The Heat Loss Model field contains a drop-down list, where you 
can select the heat loss model for the utility. There are three 
types of models:
• None
• Simple
• Detailed
εv14-72
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Utilities 14-73
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ThSimple Model
The Simple model allows you to either specify the heat loss 
directly, or have the heat loss calculated from specified values: 
• Overall U value
• Ambient Temperature
The heat transfer area, A, and the fluid temperature, Tf, are 
calculated by HYSYS. The heat loss is calculated using:
The simple heat loss parameters are:
• Overall Heat Transfer Coefficient
• Ambient Temperature
• Overall Heat Transfer Area
• Heat Flow
The Heat Flow is calculated as follows:
where:  
U = overall heat transfer coefficient
A = heat transfer area
TAmb = ambient temperature
T = holdup temperature
As shown in Equation (14.13), Heat Flow is defined as the 
heat flowing into the vessel. The heat transfer area is calculated 
from the vessel geometry. 
Q = UA(Tf - Tamb) (14.12)
Heat Flow = UA(TAmb - T) (14.13)14-73
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14-74 Dynamic Depressuring
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ThThe overall heat transfer coefficient, U, and the ambient 
temperature, TAmb, can be modified from their default values 
(shown in blue and red in the figure below).
Detailed Model
The Detailed model allows you to specify more detailed heat 
transfer parameters.
You can either apply the duty to the fluid inside the vessel or to 
the external surface of the vessel. When you select the Apply 
Duty Stream to Outside Wall checkbox, HYSYS applies the 
duty calculations to the external surface of the vessel. When you 
clear the Apply Duty Stream to Outside Wall checkbox, 
HYSYS applies the duty calculations to the fluid inside the 
vessel.
When you select Detailed from the drop-down list, four radio 
buttons appear in the Heat Loss Parameters group.
 Figure 14.38
The value in the Heat Transfer Area display field is based on the 
vessel geometry you entered on the Connections page.
Notice that the text is black, indicating the value in the field is 
calculated and cannot be changed on this page.
Refer to Section 1.6 - 
HYSYS Dynamics in 
the HYSYS Dynamic 
Modeling guide for 
more information.14-74
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ThRadio Button Description
General Allows you to manipulate the Recycle efficiencies and Ambient temperature.
In the Additional Heat Flux Injection field you can specify a heat flux value for 
the fluid contents in the vessel.
The Recycle efficiency default values are 100%, which means that all phases 
are always in thermodynamic equilibrium, and hence all phases have the 
same temperature. 
If the efficiency values are reduced (to say 10%), then the vapor and liquid 
cannot reach equilibrium instantaneously and can have different 
temperatures. No single typical number can be suggested here, and you 
should try various scenarios for the possible temperature.
Conduction Allows you to manipulate the conductive properties of the wall and insulation. 
In the Additional Heat Flux Injection field you can specify a heat flux value for 
the fluid contents in the vessel.
You can specify the following properties:
• Thickness of material. The insulation value thickness to be zero to 
model a vessel without insulation. The metal wall must have a finite 
thickness.
• Specific Heat capacity of material
• Density of material
• Conductivity of material14-75
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14-76 Dynamic Depressuring
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ThConvection Allows you to manipulate the heat transfer coefficient for inside and outside 
the vessel, and between vapour and liquid material inside the vessel.
• Fixed U. Select this radio button if you want the U values, that you 
specified, to be used throughout the calculations.
• Update U. Select this radio button if you want the U values calculated 
using the current conditions during the calculations (in other words, no 
user input.). The U values are updated while solving.
Click the Estimate Coefficient button to estimate convective heat transfer 
coefficients (U value) using current conditions.
Correlation 
Constants
Allows you to manipulate the heat transfer correlation coefficients.
• Auto Select Correlation Constants. Correlations constants are 
automatically selected based on the Grashof and Prandtl numbers.
• Use Specified Constants. You can specify the C and m constants in 
Equation (14.14) for the outside heat transfer coefficient for air.
The equation for outside heat transfer coefficient for air is:
(14.14)
All the other correlation are based on the equation below:
where:
Nu = Nusselt number
Gr = Grashof number
Pr = Prandtl number
(14.15)
Radio Button Description
h C delta_Temperature
length
--------------------------------------------⎝ ⎠
⎛ ⎞m
×=
Nu C Gr Pr×( )m×=14-76
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Utilities 14-77
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ThValve Parameters Page
The Valve Parameters page allows you to select the type of valve 
equation you want to use for your vapour and liquid outlet 
streams.
Click the Valve Equation Help button to open the Depressuring 
Valve Equation Help property view, which contains a summary 
of all the valve equations available for the Dynamic 
Depressuring utility.
Choosing the Valve Equation
You can select the Valve Equation from the Vapour/Liquid Flow 
Equation drop-down list.
 Figure 14.39
HYSYS recommends you use either the Fisher or Relief 
option to size the valve. The Fisher and Relief valve 
equations are more advanced than the other valve 
equations, and they can automatically handle choking 
conditions, and support various additional factors and 
options that can be accessed from the property views of the 
valve unit operation.14-77
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14-78 Dynamic Depressuring
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ThYou have seven options for the valve equation, and they are 
listed in the following table: 
Use the Session Preferences property view to determine the 
units for the equation.
Equation Description
Fisher Uses a ‘Fisher’ valve (the standard valve in HYSYS). This 
option allows you to specify the Cv and % opening.
You can calculate Cv for a given flow rate:
1. Click the Size Valve button located next to the Vapour 
Flow Equation field. Notice that the Size Valve button 
only appears if you select the Fisher option. The 
Vapour/Liquid Valve Sizing property view appears.
2. Enter valve sizing conditions, and select the valve type 
and solving method. 
3. Click the Size Valve button in the Valve Type and Sizing 
Method group, and notice a new Sizing Flow Rate will be 
calculated.
4. Click the OK button to accept the new size and exit the 
property view, or click the Cancel button to exit the 
property view without changing the valve size.
Refe to Section 6.7 - 
Valve for more 
information about valves.
When 
sizing the 
valve, you 
have to 
enter a 
Sizing 
Valve 
Opening 
(%).14-78
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Utilities 14-79
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ThRelief valve Uses the Relief valve operation in HYSYS. This option allows 
you to specify the orifice area, relief pressure, and full 
opening pressure.
You have to enter the following variables:
• Orifice Area/Orifice Diameter
• Orifice Discharge Coefficient. As fluid exits a 
reservoir through a small hole and enters another one, 
or flows out to the open air, stream lines tend to 
contract itself, mostly because of inertia. The 
coefficient of discharge is used to include this effect. If 
you do not want to include the effect, enter C = 1.
• Relief Pressure
• Full Open Pressure. To have the relief valve open all 
the time, set the full open pressure lower than the 
final expected vessel pressure, and set its set (or 
relief) pressure slightly lower than the full open 
pressure.
Supersonic
(14.16)
where: 
Cd = discharge coefficient (You can only enter values 
between 0 and 1 for the discharge 
coefficient.HYSYS recommends a value between 
0.7 and 1 for the discharge coefficient.)
A = area 
P1 = upstream pressure
 = upstream density
Use the Supersonic equation for modeling systems when no 
detailed information is available on the valve. The flow 
through the valve is then proportional to A (area).
Equation Description
Refer to Section 6.5 - 
Relief Valve for more 
information about Relief 
valves.
You can 
open the 
Relief Valve 
manually by 
clicking the 
Open 
Manually 
button.
F CdA P1ρ1( )0.5=
ρ114-79
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14-80 Dynamic Depressuring
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ThSubsonic
(14.17)
where: 
Cd = discharge coefficient (You can only enter values 
between 0 and 1 for the discharge coefficient. 
HYSYS recommends a value between 0.7 and 1 for 
the discharge coefficient.)
A = area 
 P1 = upstream pressure
 Pback = back pressure or valve outlet pressure
  = upstream density
If the pressure in the vessel is such that there is sub-critical 
flow (generally upstream pressure less than twice the 
backpressure), then you have no option but to use the 
Subsonic Equation. 
This equation is used in the same instances as the 
Supersonic equation except when you have subsonic flow. 
By applying this equation, you are required to specify Pback 
or the valve back pressure. By specifying Pback to be 
slightly less than the Relief Pressure, it is possible to have 
your depressuring analysis cycle between pressure build-up 
and relief. Ensure a reasonable pressure differential, and 
increase the number of pressure steps for the analysis.
Masoneilan
(14.18)
where: 
C1   = 1.6663 (SI default) or 38.86 (Field default) You 
cannot change the value for C1.
 Cv = valve coefficient 
 Cf = critical flow factor 
 P1 = upstream pressure
 = upstream density
 Yf = y - 0.148 y3 (the max value of Yf is 1)
 y = expansion factor
Taken from the Masoneilan catalogue, this equation can be 
used for general depressuring valves to flare. Often the Cv 
for a valve is known from vendor data so when Masoneilan 
is selected, the appropriate values for C1 and C2, are 
automatically set as well as the units.
Equation Description
F CdA
P1 Pback+( ) P1 Pback–( )
P1
------------------------------------------------------------- ρ1
0.5
=
ρ1
F C1CvCfYf P1ρ1( )0.5=
ρ114-80
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ThOptions Page
The Options page allows you to enter a value for the PV Work 
Term Contribution.
The PV Work Term Contribution value is used to approximate the 
isentropic efficiency. Higher values result in lower pressures and 
temperatures, and the commonly used values range from 87% 
to 98%.
General 
(14.19)
where: 
Cd = discharge coefficient (You can only enter values 
between 0 and 1 for the discharge coefficient. 
HYSYS recommends a value between 0.7 and 1 for 
the discharge coefficient.)
Av = valve orifice area 
gc = dimensionless constant = 1.0 kg.m/N.s2 (32.17 
lb.ft/lbf.s
2)
k = ratio of specific heats (Cp/Cv)
P1 = upstream pressure
 = upstream density
This equation is from Perry’s Chemical Engineering 
Handbook. Refer to it if you know the valve throat area. 
This equation makes certain limiting assumptions 
concerning the characteristics of the orifice.
No Flow Indicates that there is no flow rate output in the valve.
Use 
Spreadsheet
The flow rate spreadsheet in the Dynamic Depressuring 
subflowsheet used by the utility. This option allows you to 
edit the spreadsheet without the changes made in the 
spreadsheet getting overwritten when the utility runs. This 
option also allows more advanced users to define a 
completely different equation for the flow.
 Figure 14.40
Equation Description
F CdAvKterm gcP1ρ1k( )0.5=
ρ114-81
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ThOperating Conditions Page
On the Operating Conditions page, you can specify what you 
want to solve (valve coefficient or pressure). 
The information required on this page varies, depending on the 
type of valve equation you selected for the vapour flow on the 
Valve Parameters page.
The three specifications that apply to all valve equations are: 
HYSYS can solve either the valve coefficient or the pressure.
 Figure 14.41
Specification Description
Operating 
Pressure
Allows you to enter the initial vessel pressure. The default 
value is set to the pressure of the inlet stream.
When the utility has multiple inlet streams, then only the 
operating pressure is calculated (settle out calculations).
Time Step 
Size
Allows you to specify the integration step size. The default 
value is 0.5 seconds.
Helpful Tip: reduce the time step when you see a large flow 
rate compared to the volume.
Depressuring 
Time
The Depressuring Time is the time you want this operation 
to take. It is defaulted as 15 minutes (900 seconds) based 
on API 521, but you can alter this if required.14-82
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ThThe table below describes the required specifications for each 
equation when you select the Calculate CV or Calculate Pressure 
radio button.
The Dynamics Depressuring utility runs the dynamics 
integrator. The integrator uses a fixed integration step size 
with a default value of 0.5 seconds, and always runs for the 
total depressuring time specified. If your vessel 
depressurizes in relatively short time (for example 3 
seconds), you may need to decrease the integration step size 
and depressuring time appropriately. The sampling 
frequency of the strip chart is automatically set to the value 
of the Time Step Size.
Valve Equation
Required Specification(s)
Calculate CV Calculate Pressure
Fisher/
Masonelian
• Initial Cv Estimate
• Max Cv Step Size
• Pressure Tolerance
• Maximum number of Iterations
• Iteration Count
• Final Pressure. Based on API, it is normal to 
depressure to 50% of the starting pressure 
or to 100 psig (6.89 barg). If the 
depressuring time is reached (for API 521, 15 
minutes) before the final pressure is 
achieved, then calculations stop. The final 
pressure is used to calculate Cv for the 
vapour outlet stream.
• Cv14-83
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ThNotes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.9.2 Worksheet Tab
The Worksheet tab contains a summary of the information 
contained in the stream property view for all the streams 
attached to the operation. 
Relief • Initial Orifice Area Estimate
• Max Area Step Size
• Pressure Tolerance
• Maximum number of Iterations
• Iteration Count
• Final Pressure. Based on API, it is normal to 
depressure to 50% of the starting pressure 
or to 100 psig (6.89 barg). If the 
depressuring time is reached (for API 521, 15 
minutes) before the final pressure is 
achieved, then calculations stop. The final 
pressure is used to calculate the orifice area 
for the vapour outlet stream.
• Orifice Area
Supersonic/
Subsonic/
General
• Initial Area Estimate
• Max Area Step Size
• Pressure Tolerance
• Maximum number of Iterations
• Iteration Count
• Final Pressure. Based on API, it is normal to 
depressure to 50% of the starting pressure 
or to 100 psig (6.89 barg). If the 
depressuring time is reached (for API 521, 15 
minutes) before the final pressure is 
achieved, then calculations stop. The final 
pressure is used to calculate area for the 
vapour outlet stream.
• Area
Valve Equation
Required Specification(s)
Calculate CV Calculate Pressure
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.
Refer to the Section 
1.3.10 - Worksheet 
Tab for more 
information.14-84
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Th14.9.3 Performance Tab
The Performance tab contains the following pages:
• Summary
• Strip Charts
Summary Page
The Summary page contains a summary of all the calculated 
results.
 Figure 14.4214-85
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ThStrip Charts Page
The Strip Charts page allows you to view the results in tabular 
or graphical format.
The page contains five buttons:
• Create Plot. Generates a strip chart.
• Delete Plot. Allows you to delete a strip chart.
• Add Variable. Allows you to add the strip chart 
variables.
• View Strip Chart. Allows you to open and view the strip 
chart.
• View Historical Data. Allows you to open and view the 
historical data. The Historical Data property view 
contains two buttons that allow you to save/export the 
results: Save To CSV File and Save To DMP File.
• Create Aspen Flare System Analyzer Plot. Allows you 
to generate a Aspen Flare System Analyzer strip chart.
 Figure 14.43
The Strip Charts page allows you easy access to the strip 
charts and the historical data.
Refer to Section 1.3.9 - 
Variable Navigator 
Property View for 
information.14-86
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Th14.10 Envelope Utility
The Envelope utility allows you to examine relationships 
between selected parameters for any two-phase or three-phase 
stream of known composition, including streams with only one 
component.
14.10.1 HYSYS Two-Phase 
Envelope
The Vapour-Liquid Envelopes can be plotted for the following 
variables:
• Pressure-Temperature
• Pressure-Volume
• Pressure-Enthalpy
• Pressure-Entropy
• Temperature-Volume
• Temperature-Enthalpy
• Temperature-Entropy
For the Pressure-Temperature envelope, quality lines, and a 
hydrate curve can also be added to the plot. The remaining 
curves allow the inclusion of Isocurves (Isotherms or Isobars).
Since the Envelope is calculated on a dry basis, you must be 
careful when applying the utility to multi-component mixtures 
that contain H2O or any other component which can form a 
second liquid phase.
The Envelope utility is restricted to the Peng Robinson and 
Soave Redlich Kwong equations of state.
To add the Envelope 
utility, refer to the 
section on Adding a 
Utility.14-87
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14-88 Envelope Utility
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ThDesign Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
On the Connections page, you can select the HYSYS Two-Phase 
envelope utility and attach it to a stream. The Connections page 
also displays, the calculated critical temperature and pressure, 
as well as the cricondentherm and cricondenbar.
You can change the name of the envelope utility by typing in the 
Name field. The stream is chosen from the Select Process 
Stream property view, which is accessed by clicking the Select 
Stream button. 
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
 Figure 14.44
Select the 
HYSYS 
Two-Phase 
envelope 
utility from 
the drop-
down list.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-88
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ThPerformance Tab
The Performance tab contains the following pages:
• Plots
• Table
Plots Page 
On the Plots page, you can display different types of envelope 
graphs depending on the selected radio button in the Envelope 
Type group. 
The following sections discuss the various available envelopes in 
more detail.
 Figure 14.45
You can clear all curves on the plot at any time by clicking 
the Clear button.14-89
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14-90 Envelope Utility
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ThPressure-Temperature Envelope
When you select the PT radio button in the Envelope Type group, 
the Vapour-Liquid Envelope for a quality of 1.0 automatically 
appears.  
This is actually represented by two curves; one with a vapour 
fraction of 1.0 and the other having a liquid fraction of 1.0. 
These curves meet at the stream critical point. You can plot 
additional envelopes for different qualities simply by typing the 
desired quality (between 0 and 1) in the Quality 1 and Quality 2 
fields. 
Select the Hydrate checkbox to have HYSYS calculate and 
display the hydrate temperature curve for pressures up to the 
cricondenbar. When you select the Hydrate checkbox, you can 
select from the drop-down list the model (Assume Free Water, 
Asymmetric, Symmetric or Vapour Phase Only) to perform the 
Hydrate Formation calculations. 
 Figure 14.46
The plot on the right, shows an envelope for a quality of 0.9. 
A quality of 0.9 is represented by two curves; one with a 
vapour fraction of 0.9 and the other having a liquid fraction 
of 0.9.
For more information on 
the Hydrate calculation 
models, refer to Section 
14.12 - Hydrate 
Formation Utility.14-90
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ThPV-PH-PS Envelopes
If you select the PV radio button, the Pressure-Volume Envelope 
appears. If you select the PH radio button, the Pressure-
Enthalpy Envelope appears. If you select the PS radio button, 
the Pressure-Entropy Envelope appears.
For each of these Envelopes, you can display a maximum of 
three Isotherms (constant temperature curves) by entering 
values in the Curves group.
The figure below shows the Pressure-Enthalpy Envelope for a 
stream, with 106°C and 142°C Isotherms.
TV-TH-TS Envelopes
If you select the TV radio button, the Temperature-Volume 
Envelope appears. If you select the TH radio button, the 
Temperature-Enthalpy Envelope appears. If you select the TS 
radio button, the Temperature-Entropy Envelope appears. 
For each of these Envelopes, you can display up to three Isobars 
(constant pressure curves). Simply, enter the desired 
pressure(s) in the Curves group.
 Figure 14.4714-91
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14-92 Envelope Utility
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ThThe figure below shows the Temperature-Entropy envelope for a 
stream, with a 2068 kPa Isobar.
Table Page
You can view the envelope results in tabular format on the Table 
page. To view the tabular results of different envelopes, from 
the Table Type drop-down list select the table type for the data. 
All Isocurves and Quality lines associated with the individual 
envelopes are transferred to the table.
 Figure 14.48
Just like the Clear button in the Plots page, you can clear all 
curves data at any time by clicking the Clear button in the 
Table page.14-92
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ThDynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
The Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.
 Figure 14.4914-93
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Th14.10.2 Three-phase Envelope 
Utility
The three-phase envelope utility allows you to examine the 
relationships between selected parameters, for any stream of 
known composition, including streams with components that 
can potentially form a second liquid phase (for example, water, 
methanol, H2S, and so forth). Vapour-Liquid, Liquid-Liquid, and 
Vapour-Liquid-Liquid envelopes can be plotted for the following 
variables:
• Pressure-Temperature
• Pressure-Volume
• Pressure-Enthalpy
• Pressure-Entropy
• Temperature-Volume
• Temperature-Enthalpy
• Temperature-Entropy
The three-phase envelope is designed for the use in the oil and 
gas industries, which deal primarily with water, alcohols, 
hydrocarbon and sour gas components, and use an equation-of-
state to model their fluid systems. The three-phase envelope 
utility can be used for a wide variety of systems and property 
packages.
It is recommended that you ignore the three-phase envelope 
utility during calculation, as the utility may be slow in calculating 
phase envelopes of streams containing a large number of 
components.
You can select the Ignored checkbox on the utility’s property 
view to ignore this utility during calculations.14-94
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ThDesign Tab
The Design tab contains the following pages:
• Connections
• Notes
You can select COMThermo Three-Phase from the drop-down 
list.
 Figure 14.50
Select the 
COMThermo 
Three-Phase 
utility from 
the drop-
down list.
Refer to Section 14.2.1 
- Design Tab for more 
information on the 
Connections and Notes 
page.14-95
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14-96 Envelope Utility
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ThPerformance Tab
The Performance tab contains the following pages:
• Plots
• Table
Plots Page
The Plots page allows you to display different types of envelope 
graphs depending on the selected radio button in the Envelope 
Type group.
 Figure 14.5114-96
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ThThe following types of points are supported in the three-phase 
envelope utility:
The following sections discuss the various available envelopes in 
more detail.
Pressure-Temperature Envelope
When you select the PT radio button in the Envelope Type group, 
the Vapour-Liquid, Liquid-Liquid or Vapour-Liquid-Liquid 
envelopes automatically appears. The following are the various 
scenarios possible:
Type of Point Description
Two-phase Dew Line 1 Liquid 1 incipient
Two-phase Dew Line 2 Liquid 2 incipient
Two-phase Bubble Line Vapour incipient
Two-phase Liquid-Liquid Line Liquid 1 or Liquid 2 incipient
Two-phase Critical Point Vapour/Liquid critical on two-phase line
Two-phase Cricondentherm Maximum Temperature Point
Two-phase Cricondenbar Maximum Pressure Point
Three-phase Point Vapour/Liquid or Liquid/Liquid incipient
Three-phase Critical Point Vapour/Liquid or Liquid/Liquid incipient
Three-phase Tri-Critical Point Vapour, Liquid 1 & Liquid 2 all critical
Three-phase Bubble Line Vapour incipient
Three-phase Incipient Liquid 
Line 1
Liquid 1 incipient
Three-phase Incipient Liquid 
Line 2
Liquid 2 incipient
The plots in this manual were created using the COMThermo 
HYSYSPR property package. Aspen Technology recommends 
this property package for use with three-phase envelope 
calculations.14-97
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14-98 Envelope Utility
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ThInstability on the Two-phase Bubble Line
This scenario results in envelopes that exhibit a two-phase dew 
line and a two-phase bubble line that intersect at a critical point. 
A three-phase point is found on the two-phase bubble line from 
which emerge three branches. These include the three-phase 
bubble line where the vapour phase is incipient, a three-phase 
incipient liquid line where the liquid phase is incipient and the 
two-phase liquid-liquid line where one of the liquid phases is 
incipient. This is common when a second liquid forming 
component such as H2O is present along with some heavy 
hydrocarbons (>C7). An equimolar mixture of o-xylene, p-
xylene, H2S and H2O exhibit this behavior as shown below:
 Figure 14.5214-98
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ThInstability on the Two-phase Dew Line
This scenario results in envelopes, which exhibit two, two-phase 
dew lines which intersect at a three-phase point. From the 
three-phase point emerge two three-phase branches where 
each of the liquids is incipient. There is also a three-phase 
bubble line that intersects one of the incipient liquid lines at the 
three-phase critical point. An example of this scenario is shown 
in a methane, n-decane and water mixture shown below:
 Figure 14.5314-99
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14-100 Envelope Utility
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ThInstability on both the Two-phase Dew and the Two-
phase Bubble Lines
This scenario results in envelopes, which exhibit two, two-phase 
dew lines which intersect at a three-phase point. From the 
three-phase point emerge two three-phase branches where 
each of the liquids is incipient. It also exhibits a two-phase dew 
line and a two-phase bubble line that intersect at a critical point. 
A three-phase point is found on the two-phase bubble line from 
which emerge three branches. These include the three-phase 
bubble line where the vapour phase is incipient, a three-phase 
incipient liquid line where the liquid phase is incipient and the 
two-phase liquid-liquid line where one of the liquid phases is 
incipient. This is common when the amount of second liquid 
forming component such as water is present in small amounts 
along with hydrocarbon components. An equimolar mixture of 
C1, C3 and CO2 with a small amount of H2O exhibit this 
behavior as shown below:
 Figure 14.5414-100
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ThNon-Instability on the Two-phase Dew or the Two-phase 
Bubble Lines
This results is several sub-scenarios as follows:
• No three-phase region present. This scenario exhibits 
the regular two-phase envelope with no three-phase 
region. The two-phase bubble and two-phase dew lines 
intersect at a critical point. This is common where there 
is no second liquid forming components in the system. 
An equimolar mixture of C1, C2, C3, and n-C4 exhibit 
this behavior as show below:
• Three-phase region present along with three-
phase critical point but no two-phase critical point. 
This scenario exhibits a two-phase dew line without a 
critical point found on it. A three-phase region is present 
that is bounded by a three-phase bubble line and a 
three-phase incipient liquid line. The incipient vapour and 
incipient liquid are critical at the three-phase critical 
point. This is common when a second liquid forming 
component such as H2O is present along with light 
hydrocarbons (. The 
message Ice Forms First indicates that ice will form before the 
formation of hydrates at that condition. Exceptions are for the 
two equilibrium points, where ice and hydrates coexist: 
• the quadruple point (ice-aqueous-vapour-hydrate 
equilibrium)
• the quintuple point (ice-aqueous-vapour-liquid-hydrate 
equilibrium)
When Aspen HYSYS cases containing Hydrate Formation 
utilities (without the override specification) are loaded from 
previous versions, the default calculation method is 
automatically selected and is used for hydrate predictions in 
the current version. If you want to have control over the 
model selection (namely Assume Free Water, Asymmetric 
Model, Symmetric Model, or Vapour Only Model), you can 
override the model by accessing the Model Override page 
and then selecting the desired model.14-133
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14-134 Hydrate Formation Utility
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Th14.12.1 Design Tab
The Design tab contains the following pages:
• Connections
• Model Override
• Notes
Connections Page
On the Connections page, you can connect a stream to the 
Hydrate Formation utility and change the utility’s name. 
Click the Select Stream button to open the Select Process 
Stream property view. On the Select Process Stream property 
view, you can select the stream you want to be connected to the 
utility.
 Figure 14.7714-134
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ThThe Hydrate Formation status at the current stream conditions 
are also shown on the Connections page. 
Hydrate 
Formation Status
Description
Hydrate 
Formation Flag 
Displays the status of hydrate formation. There are 
two possibilities:
•  Will Form
•  Will NOT Form
Hydrate Type 
Formed 
Displays the types of Hydrate formed (Type I, Type 
II, Type I & II, Type H, Type I & H, Type II & H, or 
Type I & II & H). It is possible that Ice forms first, in 
which case HYSYS displays the message Ice Forms 
First in this field. If the stream temperature is higher 
than the formation temperature, then No Types is 
displayed in this field.
Calculation Mode Possibilities are Use 2-Phase Model, Use 3-Phase 
Model, Use SH Model, and Assume Free Water.
Inhibitor 
Calculation
Possibilities are Included and Not Included.14-135
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14-136 Hydrate Formation Utility
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ThModel Override Page
The Model Override page allows you to gain control over a 
specific model for hydrate predictions. You can override the 
default model by selecting the Override Default Model 
checkbox and selecting an appropriate model for hydrate 
calculations as shown in the following figure.
Notes Page
The Notes page provides a text editor where you can record any 
comments or information regarding the utility or to your 
simulation case in general.
 Figure 14.78
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-136
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Th14.12.2 Performance Tab
The Performance tab contains one page, Formation T/P. The 
Formation T/P page contains two groups:
• Formation Temperature at Stream Pressure
• Formation Pressure at Stream Temperature
Formation Temperature at Stream Pressure 
Group
The Formation Temperature at Stream Pressure group displays 
the formation temperature at which hydrates are formed at the 
stream pressure. The hydrate type formed at this formation 
temperature and the calculation mode are also shown. In 
addition, information on equilibrium phases that exist at the 
predicted formation temperature and notification of the inhibitor 
calculation are also displayed.
The Equilibrium Phases field can be V-H, Aq-H, L-H, V-Aq-H, V-L-
H, Aq-L-H, or V-Aq-L-H (where V, Aq, L, and H refer to vapour, 
aqueous, non-aqueous liquid, and hydrate phases, 
respectively). Refer to the Hydrate Inhibition section for a 
detailed description of the inhibitor calculation information.
 Figure 14.79
The hydrate types and 
calculation models are 
discussed in the Hydrate 
Calculation Models 
section.14-137
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ThFormation Pressure at Stream Temperature 
Group
The Formation Pressure at Stream Temperature group displays 
the formation pressure at which hydrates are formed at the 
stream temperature. Similar to the Formation Temperature at 
Stream Pressure Group, this group shows
• the hydrate type formed
• the equilibrium phases at the predicted formation 
pressure
• the calculation mode used
• the notification of the inhibitor calculation
Unlike the Performance tab, information on the equilibrium 
phases is not available in the Design tab. This is because the 
actual phase equilibrium at the given stream condition (with 
both stream pressure and temperature fixed) could be different 
from the phase equilibrium predicted at the condition where 
only the stream pressure or temperature is fixed. Information 
on the actual phase equilibrium at the given stream condition 
might be derived from the stream flash calculation. 
Hydrate Inhibition
To avoid or inhibit the formation of hydrates, you can do one of 
the following:
• Set the operating conditions to be outside the predicted 
equilibrium curve for hydrates (in other words, set the 
operating temperature to be higher than the hydrate 
formation temperature) 
• Inject inhibitors such as glycols (for example, EG, DEG, 
TEG) or alcohols (for example, methanol) to suppress the 
formation of hydrates. The inhibitors serve as antifreeze 
agents and depress the freezing conditions of hydrates.
The hydrate types and 
calculation models are 
discussed in the Hydrate 
Calculation Models 
section.14-138
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ThTo inhibit the formation of hydrates of a given stream in the 
flowsheet, you must install a stream containing the inhibitors. 
We recommend that you create an inhibitor stream which 
contains the inhibitor solution (for example, 30 weight% of 
methanol in water) and then use the Mixer operation to mix the 
inhibitor stream with the process stream to create a new stream 
which contains the desired amount of the inhibitor. You then can 
access the Hydrate Formation utility to find the new solid 
hydrate formation condition of the new stream. Due to the 
limitation of the models used, a high concentration of inhibitors 
is not recommended in the hydrate prediction (for example, the 
methanol concentration should not exceed 50 weight% with 
respect to water content when the given stream consists of 
methane11).
The inhibitor model that Aspen HYSYS uses was developed using 
available experimental data obtained at the saturated water 
condition for the Structures I and II. At the saturated water 
condition, a free-water (aqueous) phase must exist. Therefore, 
Aspen HYSYS performs inhibition calculations only when there is 
an aqueous phase after an equilibrium flash. You must ensure 
that the stream of interest has sufficient amount of water to be 
at a saturated water condition. This inhibitor model is also 
applied to the Structure H hydrate. However, since there is no 
experimental data available for the inhibition using alcohols and 
glycols on the Structure H hydrate, the accuracy of this model 
cannot be ascertained. Use it with care and only to provide a 
rough estimate.
Using the Assume Free Water model is not applicable here 
because the inhibitor calculation is not included in this 
calculation mode/model. Additionally, due to the limitation of 
the experimental data, the inhibitor calculation is not included 
when the 2-Phase model is used (either as determined by the 
Default model or specified using Model Override).
Since three phase thermodynamics are used to perform the 
flash calculation, the phase distribution of the components, 
including water and the inhibitors, can be calculated 
rigorously. Therefore, inhibitor losses in the hydrocarbon 
liquid and vapour phases are properly taken into account.14-139
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14-140 Hydrate Formation Utility
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ThThe Peng-Robinson (PR) equation of state was not originally 
designed for non-ideal components such as methanol and 
glycols. You should ensure the resulting distribution of the 
components in all phases is satisfactory, especially if three 
phases exist. The solubility of methanol in the hydrocarbon and 
aqueous phases is optimized with the PR equation of state for 
the methanol-HC-water VLE. Make further adjustment to the PR 
interaction parameters to meet your own specifications.
Overall, this approach should be more accurate than using 
Hammerschmidt's equation which was developed specifically for 
dilute solutions of antifreeze agents. The Hammerschmidt 
equation applies only for typical natural gas mixtures and for 
solute concentrations less than 20 mole per cent. Although it is 
applied for cases beyond this region with reasonable success, 
this is attributed to a number of compensating factors. For 
validation of this model, refer to GPA Research Report RR-66. 
14.12.3 Dynamics Tab
The Dynamics tab allows you control how often the utility gets 
calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility is 
recalculated every 10th pressure flow step. This helps speed up 
your dynamic simulation since utilities could require some time 
to calculate.
 Figure 14.8014-140
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Utilities 14-141
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ThThe Use Default Periods checkbox lets you set the control 
period of one utility to equal the control period of any other 
utilities that you have in the simulation. For example, if you 
have five utilities and require them all to have a control period 
of 5 and currently the value is 8, with this checkbox selected if 
you change the value in one utility all the other utilities change. 
Alternatively, if you want all the utilities to have different 
values, then clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.14-141
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14-142 Master Phase Envelope Utility
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Th14.13 Master Phase 
Envelope Utility
The Master Phase Envelope Utility allows you to calculate the 
three-phase envelope for multiples streams of known 
compositions, including streams with only one component.
14.13.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
The Connections page allows you to do the following: 
• Rename the utility by typing the new name in the Name 
field.
• Add a stream by clicking the Add Stream button to open 
the Select Process Stream property view.
• Remove a stream by selecting the stream and clicking 
the Remove Stream button.
• Rearrange the order of the streams by clicking the Order 
Streams... button. In the Order Streams property view 
that appears, click the individual stream and then the 
Add or Remove button to arrange streams in the new 
list.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-142
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Utilities 14-143
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Th14.13.2 Performance Tab
The Performance tab contains the following pages:
• Table
• Plots
Table Page
You can view the envelope results in tabular format on the Table 
page.  
To view the tabular results of different envelopes for the desired 
stream, select a stream from the Stream drop-down list then 
select a table type from the Table Type drop-down list. All 
Isocurves and Quality lines associated with the individual 
envelopes are transferred to the table.
 Figure 14.81
The Table page allows you to display the envelope results for 
one stream at a time.
Stream drop-down list Table Type drop-down list14-143
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14-144 Master Phase Envelope Utility
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ThPlots Page 
The Plots page allows you to display different types of envelope 
graphs for multiple streams.
You can plot the envelope graphs for the desired stream(s) by 
clicking the Select Streams To Plot radio button. All the streams 
that have been attached to the utility are listed in the table.
Click the Plot radio button to plot the selected streams. 
Depending on the radio button selected, the vapour-liquid, 
liquid-liquid, and vapour-liquid-liquid envelopes can be plotted 
for the following variables:
• Pressure-Temperature
• Pressure-Volume
• Pressure-Enthalpy
• Pressure-Entropy
• Temperature-Volume
• Temperature-Enthalpy
• Temperature-Entropy
 Figure 14.8214-144
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Utilities 14-145
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Th14.14 Parametric Utility
The Parametric Utility enables you to create neural networks to 
replace portions of the simulation flowsheet. You can now easily 
configure the utility to capture data from the flowsheet model. 
You can define a list of variables that you want to perturb 
(manipulated variables), and variables you want to record 
(observable variables). The utility allows you to quickly create 
lists of variables and to re-use variable lists. The data generated 
can be exported in a comma-delimited style in a number of 
different formats. 
The utility originated as a set of tools for building a Parametric 
model (PM) within the HYSYS environment. The utility integrates 
Neural Network (NN) technology into its framework. The major 
function of the Parametric utility is to approximate an existing 
HYSYS model with a Parametric model.
Using a Parametric model with neural network capability to 
approximate a HYSYS model significantly improves the 
robustness of the model, and reduces its calculation time 
thereby improving overall performance. The accuracy of the 
model depends upon the data available, and the type of model 
being approximated. 
The object of analysis can be a collection of unit operations, an 
entire flowsheet, or a number of selected variables. Using input 
and output data sets as training data, the neural network 
algorithm determines the Parametric model parameters. This 
step is called training but can also be referred to as regression 
or identification.
Steps one to four describe the general procedure for the Utility:
1. Select scope.
2. Select variables (manipulated and observable).
3. Define test datasets.
4. Generate data.14-145
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14-146 Parametric Utility
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ThSteps five to six describe the general procedure to use for NN:
5. Train.
6. Validate.
The Parametric Utility main purpose is to generate data and 
training for Neural Networks. This includes setting up the utility, 
and generating the data with some additional steps used in 
building the NN.
14.14.1 Neural Networks
What is a Neural Network?
A Neural Network (strictly ‘Artificial Neural Network’ as opposed 
to a ‘Biological Neural Network’) is a mathematical system with 
a structure based on the brains of mammals. The Artificial 
Neural Network is split into many basic elements (equivalent to 
neurons in biological systems), which are linked by synapses.
Neural Networks model the relationship between input and 
output data. They are particularly suited to the kind of problems 
that are too complex for traditional algorithm based modeling 
techniques, for example pattern recognition and data 
forecasting. There are a number of types of Neural Networks, 
but HYSYS uses a Multi-Layer Perceptron (MLP) type model.
The Neural Network is trained through a learning process where 
synaptic connections between neurons are constructed and 
weighted. The Neural Network is trained in an iterative manner. 
A set of input data and desired output data is repeatedly 
supplied, and based on the errors between the Neural Network 
calculated outputs and the desired outputs, the connections are 
adjusted for the next iteration.14-146
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Utilities 14-147
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ThNeural Networks in HYSYS
Neural Networks provide a performance and cost effective 
modeling tool, and can extend the capabilities of traditional 
statistics, modeling, and control. They can be applied in both 
linear and non-linear systems where first-principles modeling is 
too costly or difficult. 
Neural Networks provide flexible and powerful techniques for 
data analysis, and can be used for: 
• dynamic and static process modeling
• nonlinear and adaptive control
• inferential predictions
• time series prediction
• multivariate pattern recognition
HYSYS includes a Neural Network calculation tool that can be 
used to approximate part (or all) of a HYSYS model. It can be 
trained to replace either the first principles calculations usually 
done by HYSYS, or to simulate a unit operation that cannot be 
modelled using the first principles.
Using a Neural Network solver offers a number of advantages:
• It is significantly faster that a first principles solution.
• It offers increased robustness so that a result will always 
be possible.
There are three parts to the HYSYS Neural Network 
implementation:
• Parametric Utility. Where the Neural Network is 
configured and trained.
• Parametric Unit Operation. Allows the Neural Network 
to appear as a unit operation on the flowsheet, and it is 
typically used when taking a “black box” approach.
• Neural Network Manager. Allows you to switch Neural 
Network (NN) Objects into appropriately configured 
Parametric Utilities, and to generate simple Neural 
Network’s from external data.
When using a Neural Network, always be aware that results 
are valid only within the range over which the Neural 
Network was trained.
Refer to Section 14.14.4 
- Neural Network (NN) 
Manager for more 
information on the Neural 
Network Manager.14-147
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14-148 Parametric Utility
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Th14.14.2 Variables
The parameters of the Parametric model are determined either 
through HYSYS simulation runs or based on historical plant data 
(the latter also requires the use of the Parametric unit 
operation). There are three types of variables:
• Observable
• Manipulated
• Training
The variables are discussed in the following sections.
Observable Variables
Observable variables can be either input or output variables 
within the HYSYS PFD model. When HYSYS is used to generate 
training datasets for the Parametric model, a number of 
simulation runs must be performed. During the simulation run, 
the simulation solution engine calculates each operation in the 
HYSYS PFD. The observable variables are the HYSYS variables 
whose values are known, and used as training data when 
calculating the Parametric model.   
Manipulated Variables
Manipulated variables are the variables being modified in the 
Parametric utility, and are obtained from the HYSYS PFD model 
simulation.
Observable input and output variables can each include both 
input and output stream variables. A HYSYS model 
parameter with a varying value can be either an observable 
input variable or an observable output variable within the 
Parametric model.
Refer to Section 5.6 - 
Parametric Unit 
Operation for details on 
the Parametric unit 
operation.14-148
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Utilities 14-149
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ThTraining Variables
Training variables are a combination of both the observable and 
manipulated variables used to develop the Parametric model. 
The term “training” refers to the task of using the data sets 
available as a form of “learning” that, in effect, fits the model 
parameters to the specifications.
The Parametric model approximates the HYSYS model in the 
sense that, given the same values for the training input 
variables, the values of the output variables from the Parametric 
model must be close to the values of the output variables from 
the HYSYS model.
There are no methods for training neural networks that can 
“create” information that is not contained in the training data. 
The neural network model is only as good as its training data.
14.14.3 PM Utility Property 
View
The PM Utility property view is composed of several tabs that 
are described in the following sections. The status bar at the 
bottom of the screen provides you with hints and descriptions of 
what the fields represent.
To add the Parametric 
Utility, refer to the 
section on Adding a 
Utility.14-149
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14-150 Parametric Utility
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ThConfiguration Tab
The Configuration allows you to specify the name of the utility, 
calculation options, and select HYSYS objects to be included in 
the Parametric model.
The Configuration tab defines the scope of the utility and lists 
the equipment from which you can select objects to configure. 
Once objects have been added to the final list, you must click 
the Accept List button and then click the Next button to 
proceed. 
 Figure 14.8314-150
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Utilities 14-151
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ThThere are two Calculation Options available which are described 
below:
The Accept List button accepts the changes and obtains all 
variables known to the selected objects from the HYSYS 
flowsheet. 
Calculation 
Options
Description
Embedded into 
HYSYS 
Flowsheet
This checkbox allows the trained neural network to 
replace the traditional HYSYS solver for the objects 
included in the NN.
Advanced option 
mode
This checkbox enables more flexibility in the selection 
of manipulated variable sets. If selected, the 
Embedding option checkboxes are displayed.
• Intelligent Embed - For embedding, it is required 
that the stream variables selected are a flashable 
set. If checked, and the streams are over-
specified, the utility does not query the user and 
selects a sub-set of variables that allows the 
streams to flash. If the streams are under-
specified, the utility will not warn the user. 
• Initial Query Only - The above queries occur only 
once on the initial embedding unless the PMUtil 
configuration is changed.
• Range Check - If the manipulated variable values 
are outside the range than the Neural Network in 
the Parametric Utility was trained upon, then the 
Parametric Utility is unembedded.
You cannot advance to the next tab (Select Variables) unless 
you click the Accept List button.14-151
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14-152 Parametric Utility
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ThSelect Variables Tab
The Select Variables tab allows you to filter your objects so that 
you can add manipulated and observable variables. The various 
functions on this tab are described below.
When you select the Manipulated radio button, a group of radio 
buttons become available for you to select a filter type from. 
This is to help you choose your manipulated and observable 
variables:
• All. Shows all chosen variables of the selected type in 
the table. If you didn’t choose any, none will appear.
• Object Filter. Shows a list of unit operations and objects 
in a tree browser for selection.
• FlowSheet Filter. Shows a list of subflowsheets 
contained in the case and any related variables.
• Variable Filter. Shows all flowsheet variables.
 Figure 14.84
The Property Filter radio button only appears if the 
Observable radio button is selected.14-152
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Utilities 14-153
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ThThe table below describes the available objects on the Select 
Variables tab. 
The following buttons/radio buttons/fields are not always 
visible. Certain ones appear when the Manipulated or 
Observable radio buttons are selected, and others appear 
when you click the Change/Accept Configuration button.
Object Description
Build Streams 
button
Builds variables based on the stream information in the 
utility scope. It selects all variables that can be 
modified in the streams as Manipulated variables and 
all stream variables as Observable Variables (often 
duplicating).
If you have already created a set of variables, you 
must click the Change Configuration button to see this 
button.
Remove All 
button
Removes all variables from the table.
If you have already created a set of variables, you 
must click the Change Configuration button to see this 
button.
Build Flashable 
Streams button
Selects all variables in the streams that can be 
modified and sets them as manipulated. For 
observable variables, it takes as many variables as 
necessary from the streams to flash without a 
inconsistency error. 
The flash used is a T/P/F flash.
Display Mode 
group
The group contains two radio buttons to choose from:
• Configuration
• All
The radio buttons control how many columns appear in 
the variables table, and what type of data is displayed.
Build Filter 
button
Allows you to create a filter that adds all objects in the 
utilities scope that match your filter criteria. For 
example, if you want every stream temperature, 
pressure, and volume flow, you can build a filter to add 
all streams with these three variables. 
You can save and reuse these filters.
If you have already created a set of variables, click the 
Change Configuration button to see this button.
Apply Filter 
button
Once a filter is built, click this button to add all 
variables that meet the filter criteria.
Click the Change Configuration button to see this 
button.14-153
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14-154 Parametric Utility
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ThWhen you are satisfied with your selection of observable and 
manipulated variables, click the Accept Configuration button. 
The current variable configuration is accepted, and you can now 
access the Data tab.
Change/Accept 
Configuration 
buttons
You must click the Change Configuration button when 
you want to change pre-selected variables. The 
Change Configuration button then becomes the Accept 
Configuration button. 
Any new changes will be updated when you click the 
Accept Configuration button.
Range field If you change the Range, then the Low Limit/High Limit 
of the Manipulated Variables changes.
For example, a value of 0.1 gives you a Low-High of 
. 
The Low Limit and High Limit are max/min used when 
generating random values for the manipulated 
variables on the Data tab. This is important when you 
want to randomly select the manipulated variables 
commonly applied with neural networks.
This field is only visible when the Manipulated radio 
button is selected.
Manipulated 
radio button
Displays manipulated variable property view.
Observable radio 
button
Displays observable variable property view.
Select All button With either the observable or manipulated variables in 
the table, this button selects all checkboxes in the 
active list.
Click the Change Configuration button to see this 
button.
Un-Select All 
button
With either the observable or manipulated variables in 
the table, click this to unselect all checkboxes in the 
active list.
Click the Change Configuration button to see this 
button.
Remove 
Unselected 
button
Removes all unselected variables from either the 
observable or manipulated tables.
Click the Change Configuration button to see this 
button.
Transitions Off/
On buttons
The Transition On/Off buttons only appear when 
stream cutters are used, and you have selected the 
Advanced option mode. 
Stream cutters are inserted into the boundary streams 
when a subset of the flowsheets objects is selected. 
Object Description
10%±
Refer to Section 5.11 - 
Stream Cutter for 
more information.14-154
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Utilities 14-155
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ThData Tab
The Data tab allows you to configure and generate input and 
output data sets for the Parametric model based on HYSYS 
simulations. Training data sets are generated by using stepwise 
changes to the manipulated input variables to produce varying 
output results.
The table below describes the objects on the Output File Options 
group and Data Set Options group.
 Figure 14.85
Object Description
Output File Options group
Create as new 
radio button
Create as new allows you to name and create a new 
file to store your data. This is a binary file that is used 
internally by the PM Utility and cannot be read in as a 
CSV file. 
When sharing a case in the PM utility, and the data has 
been generated, make sure the binary data file is also 
transferred, otherwise the data will have to be re-
generated.
Used to reset manipulated variables to their original values after 
data generation.14-155
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14-156 Parametric Utility
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ThThe Manipulated Variable Set matrix is shown below with its 
corresponding buttons.
The table below describes the objects on the Manipulated 
Variable set matrix.
Append to 
existing radio 
button
Append to existing saves your data to an existing *.dat 
file. This is useful when you want to append new data 
to previously generated data.
Output File 
Browse button
Click to browse for a *.dat file.
View File Info 
button
Displays a property view showing the *.dat file info, 
such as maximum file size, total number of records, 
and so forth.
Output File Head 
Name field
The path for the output file is specified here.
Output File 
Extension field
Specify the type of file you want to save the output file 
as.
Data Set Options group
Build Random 
Dataset button
Picks random manipulated variables between high and 
low bounds for each variable.
Read from CSV 
File button
Click to browse for a *.csv file that you can import. It 
contains manipulated set points from a comma 
delimited file instead of entering data manually. In this 
file a line that begins with a * is taken as a comment 
line. 
 Figure 14.86
Object Description
Size column Enter the number of manipulated variable data sets 
you want to run. When you change this number, the 
number of data set columns associated with the 
variable list changes.
Generate Data 
button
Initiates the simulation engine to generate training 
data for the parametric model based on the HYSYS 
model.
Object Description14-156
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Utilities 14-157
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ThWhen setting up your Parametric model for the first time, click 
the Create as new radio button. This allows you to name and 
create a new file to store your data. Data is then written to an 
external file based on the default name and location (path) 
listed.
Later, if you want to add to the number of data sets used for 
training (thereby increasing the accuracy of your Parametric 
model), choose the Append to existing radio button. Data is 
then written to an external file based on the default name and 
location listed (as shown in the previous figure). 
The Output File Options group displays information related to 
the training data file to be generated by the Parametric Utility. 
The Number of the Size field defines the number of data sets 
that are generated using the HYSYS model. Increasing this 
number increases the likelihood that the Parametric model is a 
“good fit” for the flowsheet model, however, the data takes 
longer to generate.
Choosing the Number of Data Sets
The number and range of your data sets should span the 
intrinsic dimension of your variable set. For example, completely 
span the range of your variables once all constant or linear 
relationships have been removed. Failure to do this may cause 
the Neural Network to fit a constant or linear relationship 
between two variables when a more complex one exists.
Export to CSV... 
button
Once data has been generated, you can save 
manipulated and observable data to a *.csv file; you 
can choose between a number of formats.
View tables... 
button
Views the manipulated and observable variables in the 
HYSYS environment. This is only available when the 
Advanced Option Mode is selected.
If you have changed the model’s configuration, you should 
not append to existing data sets.
Object Description14-157
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14-158 Parametric Utility
ww
ThWhen the data has been generated, and the Init/reset button 
on the Training tab is pressed, the PM Utility displays a list of the 
MLP units, the number of inputs, the number of outputs, and the 
number of hidden units.
A very rough rule of thumb, used by some researchers, is to 
count the number of weights in the network and multiply by 10. 
If you have an, n, input network with, k, hidden units and, m, 
outputs, then the number of weights (internal parameters 
adjusted during training) is: 
So if n = 13, m = 12, and k = 13, there will be 350 weights in 
the network. In practice, one can often manage with the fewest 
amount of data sets, but you should not have more weights 
than training examples.
This number of input, output, and hidden training variables in 
the NN is only available once the data has been generated, and 
the relationships between the selected input and output 
variables are assessed. As such an incremental approach to 
generating data is recommended. Assume that there is only one 
hidden layer (in other words, in the above k = 1) and generate n 
+ 1 + 2m data sets (48 data sets for this example).
Proceed to the Training tab and press the Init/Reset button. 
The number of Input, Output, and hidden units in each MLP are 
displayed. Calculate the number of weights. If the number of 
weights are less than the number of data sets that have been 
generated, then you may consider training the NN. If the 
number of weights is greater than the number of data sets 
generated, return to the Data tab and click the Append to 
Existing radio button. Enter in a completely new set of data 
(using the same data does not help), and click Generate Data 
button again. Repeat this process until enough data sets have 
been generated, and appended to the original data file.
This is only a rough rule of thumb. There is no substitute for 
understanding the system being modelled and looking at the 
data to check the regions where there are rapid changes 
between input and output, and then providing more 
examples in those regions.
n 1+( )k k 1+( )m+14-158
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Utilities 14-159
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ThTraining Tab
The Training tab allows you to generate a Parametric model 
based on the HYSYS training data. Data sets generated on the 
Data tab are used as training variables. The training algorithm 
determines the parameter values of the neural network model 
based on the input and output data sets. The end result is a 
Parametric model which approximates its HYSYS model 
counterpart. 
The set of Training buttons are described below:
 Figure 14.87
Button Description
Init/Reset Use this button before running the training algorithm or 
when you need to reset the Parametric model.
Confirm Allows you to confirm the current training configuration.
Train Initiates the training algorithm to train the neural network 
based on the data sets generated by the HYSYS model.14-159
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14-160 Parametric Utility
ww
ThThe Sub-group models group allows filtering of neural network 
data using three radio buttons as described below:
The Display Mode group displays model data in the table based 
on the radio button selected. 
You can also change the number of hidden layers in the MLP, and 
the number of cycles (in other words, number of times the data 
is presented to the nodes). Changing these may affect the 
efficiency of your model and is only recommended for the 
advanced user.
View Table... Allows the viewing of training data in table format. 
Compares the HYSYS training data with Parametric model 
data. 
View Graph... Allows the viewing of training data in graphical format. 
Compares the HYSYS training data with Parametric model 
data.
Radio Button Description
All Displays both Simple and MLP combined.
Simple Displays constant and linear variables. Those relationships 
that are not modeled by the MLP.
MLP Displays Multilayer Perceptrons. Those relationships that 
are modeled by neural networks.
Radio Button Description
All All information associated with the model (type of model, 
number of inputs/outputs, and all variables associated with 
neural net trainer).
MLP Model Displays the model type and information regarding NN 
representation parameters.
Simple Model Displays the model type, number of inputs and outputs.
Trainer Information that describes the training parameters for a 
given model.
Button Description14-160
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Utilities 14-161
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ThThe matrix group and the buttons below are described in the 
following table:
In Advanced Mode, the following buttons are available on the 
Training tab:
When in Advanced Mode, you can modify the following 
parameters:
Object Description
Blocks radio 
button
Allows you to can examine the structure if data is put 
into multiple blocks or NN.
Models radio 
button
Allows you to examine the structure if data is put into 
model types. Model types available are: Manipulated, 
Constant, Ignored IntStr, and Simple Linear.
PMBlock Number 
field
Displays the PM block number.
Button Description
Load NN Allows you to load the Neural Network (*.nn file) into 
another Parametric Utility (of the same configuration), 
same Parametric Utility, or used with the Neural Network 
Manager.
Save NN Allows you to save a trained Neural Network to a specific 
*.nn file.
Parameter Description
#Iters Maximum number of passes the training algorithm 
will take.
Relative Tolerance Ratio of the change in error between two iterations 
to the actual error. If the value is below the 
tolerance training will stop.
Abs Tolerance If the training error is below this value, training 
will stop.
Refer to Section 14.14.4 
- Neural Network (NN) 
Manager for more 
information.14-161
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14-162 Parametric Utility
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ThValidation Tab
The Validation tab is the final phase in developing a Parametric 
model. On this tab, validation of the model is performed by 
generating validation points using both the Parametric model 
and the HYSYS model and comparing the results.
The Validation options are described below:
 Figure 14.88
Button Description
Validation 
Setup
Allows you to configure validation setup options which 
include the Number of Validation Points and the Random 
Speed used in generating the validation points.
PM runs Runs the Parametric model to generate validation data 
based on the Parametric model.
HYSYS runs Runs the HYSYS model to generate validation data based 
on the HYSYS model.
View Tables... Allows the viewing of validation data in table format. 
Compares the HYSYS validation data with Parametric 
model data. 
View Graph... Allows the viewing of validation data in graphical format. 
Compares the HYSYS validation data with Parametric 
model data.14-162
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Utilities 14-163
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ThThe Display Mode group has two radio buttons:
The Filter group filters objects based on four radio button 
selections:
After you have a trained NN, you can embed it into the HYSYS 
flowsheet to replace the objects you selected earlier by the 
trained NN; use the Embedded into HYSYS Flowsheet checkbox 
on the Configuration tab. If your streams are over specified, 
HYSYS filters the stream information for you to avoid 
consistency errors.
Radio Button Description
All Displays all the variable information.
Validation Displays the validation range and error.
Radio Button Description
All Shows all variables.
Objects are filtered differently depending upon whether 
they are manipulated or observable. 
Objects Shows the variables.filtered by the flowsheet objects.
Simple Linear Shows the variables which have a constant or linear 
relationship.
MLP Models Shows the variables which are used in the MLP model.14-163
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14-164 Parametric Utility
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Th14.14.4 Neural Network (NN) 
Manager
You can access the Neural Network Manager by clicking the NN 
Manager button on the Configuration tab of the Parametric 
Utility property view.
 Figure 14.89
The NN Manager button only appears when you select the Advanced option mode 
checkbox in the Calculation Options group of the Parametric Utility Configuration 
tab.14-164
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ThThe Neural Network Manager allows you to switch Neural 
Network (NN) Objects into appropriately configured Parametric 
Utilities, and to generate simple Neural Network’s from external 
data.
The Config Choose tab allows you to switch between the two NN 
Manager modes:
• PMUtilities Manager 
• NN Creation
PMUtilities Manager Mode
There are four tabs available for the PMUtilities Manager mode:
• Set Up
• PMUtil Config
• NN Config
• Embedding Control
 Figure 14.9014-165
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14-166 Parametric Utility
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ThSet Up Tab
The Set Up tab displays the list of available Parametric Utilities 
and Neural Network Objects associated with the Parametric 
Utilities. 
The Set Up tab consists of the following fields:
The following buttons allow you to load, remove or associate a 
Neural Network object with the Parametric Utilities.
 Figure 14.91
Field Description
Selected PM Utility Displays the Parametric Utility that you have 
selected from the list of available PM Utilities 
Selected NN Displays the Neural Network (NN) object you have 
selected from the list of available NN’s.
NN in PMUtil Displays the Neural Network (NN) object that is 
loaded in the Parametric Utility.
Button Description
Load NN From File Loads a Neural Network object into the Neural 
Network Manager and associates it with the 
Parametric Utility that you selected from the list of 
available PM Utilities. 14-166
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ThParametric Utilities which have been trained are automatically 
added to the list of available PM Utilities.
Neural Network objects have to be created from a trained Neural 
Network; on the Training tab of a Parametric Utility property 
view, in advanced mode, you can save or load a NN (.nn file) 
using the Save NN or Load NN buttons.
Neural Network objects must have the same configuration as 
the Parametric Utility object they are being loaded into. Stream 
and unit operation names can be different, but the list of 
Manipulated and Observable variables must have the same type 
of variable in the same order.
PMUtil Config Tab
On the PMUtil Config tab you can view a list of the Manipulated 
and Observable variables for the Parametric Utility you selected 
from the list of available PM Utilities on the Set Up tab.
Remove NN From 
List
Removes the selected Neural Network object from 
the list of available NN’s and the Neural Network 
Manager.
Load NN into PMUtil Loads the selected Neural Network object from the 
list of available NN’s into the selected Parametric 
Utility from the list of available PM Utilities.
 Figure 14.92
Button Description14-167
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14-168 Parametric Utility
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ThYou can also view the Manipulated and Observable variables 
high and low values for the Parametric Utility you selected from 
the list of available PM Utilities on the Set Up tab.
NN Config Tab
On the NN Config tab you can view a list of the Manipulated and 
Observable variables for the Neural Network object you selected 
from the list of available NN’s on the Set Up tab. 
You can also view the Manipulated and Observable variables 
high and low values for the Neural Network object you selected 
from the list of available NN’s on the Set Up tab.
 Figure 14.9314-168
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ThEmbedding Control Tab
The Embedding Control tab allows you to control the different 
embedding options.
The Embedding Control tab consists of three groups:
• PMUtil Embedding Controls are described in the table 
below:
• NN Manager Parameters. You can select the Deferred 
Embed checkbox, if the Neural Network Manager needs 
to switch a Neural Network into a Parametric Utility, but 
there is an adjust or recycle in the scope of the 
Parametric Utility, then the switch will be done after the 
adjusts and recycle have converged. 
 Figure 14.94
Controls Description
Embed Embeds the Parametric Utility into the flowsheet.
Switch NN’s Switches the Neural Network’s into the Parametric Utility 
automatically to the one that fits the manipulated variable 
values most appropriately.
Intel Embed The PMUtil makes choices to maximize a successful 
embedding, if they need to be made.
Init Query If the you need to be queried on an embed, you will only 
be queried once.
Range Check If the manipulated variable values are outside the range 
than the Neural Network in the Parametric Utility was 
trained upon, then the Parametric Utility is unembedded.14-169
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14-170 Parametric Utility
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Th• Variable Weights. The weights used to determine the 
NN which fits the manipulated variable values most 
appropriately. The higher the values of the weight, the 
greater effect that variable bound has on selecting the 
NN. A weight of 0 shows the variable bound will have no 
effect.
NN Creation Mode
There are two tabs available for the NN Creation mode:
• NN Generation
• NN Utilization
NN Generation Tab
There are three groups on the NN Generation tab:
• CSV File Configuration. Allows you to specify the row 
or column format for the data file, browse for the data 
file, and load the data file into the Neural Network 
Manager by clicking the Load Data button. 
• Data View. Displays the data loaded from the CSV file.
• NN Training. Allows you to modify training parameters 
(#Iterations, Abs Tolerance, Relative Tolerance, #Hidden 
Layers, Scaling), and displays the Error of the trained 
Neural Network. When you click the Train NN button, it 
starts the training algorithm.
 Figure 14.95
Refer to Data File 
Format Group section 
from Section 5.6.2 - 
Design Tab in the 
HYSYS User Guide, for 
more information on 
specifying the row or 
column format for a data 
file.14-170
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ThNN Utilization Tab
The NN Utilization tab allows you to save or load trained Neural 
Network’s (.mlp files), and utilizes the *.mlp files for displaying 
the Inputs and Outputs in the table. 
 Figure 14.96
The Neural Network’s stored here are in a different format 
from those used in the PMUtil Manager mode as they do not 
contain variable type information. The two formats are 
currently not compatible.14-171
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14-172 Pipe Sizing
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Th14.15 Pipe Sizing
With the Pipe Sizing utility you can perform design calculations 
on any of the case streams. Results include pipe schedule, pipe 
diameter, Reynolds number, friction factor, and so forth.
14.15.1 Design Tab
The Design tab contains the following pages:
• Connections 
• Notes
 Figure 14.97
To add the Pipe Sizing 
utility, refer to the 
section on Adding a 
Utility.14-172
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ThConnections Page
On the Connections page, you can select the stream that 
represents the pipe you want to size, the calculation type and 
characteristics of the pipe.
You can also remove or change the streams to be used by 
clicking the Select Stream button, and changing the selection in 
the Select Process Stream property view.
General Procedure
The following are the steps to pipe size a selected stream.
1. On the Design tab, click the Connections page.
2. Click the Select Stream button. The Select Process Stream 
property view appears.
3. Select a stream for the analysis from the Object list. 
4. Click the OK button to return to the Pipe Sizing property 
view.
5. You must select a calculation type from the Calculation 
Type drop-down list. The options available are:
• Max. Diameter. The input required includes the pipe 
schedule, and the pressure drop in the pipe.
• Pressure Drop. The input required includes the pipe 
schedule, and the pipe diameter.
 Figure 14.9814-173
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14-174 Pipe Sizing
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ThThe following fields are available for each stream chosen.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
 Figure 14.99
Object Description
Calculation 
Type
Allows you to choose between two calculation types: 
• Max. Diameter
• Pressure Drop
Schedule Allows you to select a pipe schedule. You have four choices:
• None
• Schedule 40
• Schedule 80
• Schedule 160
If you selected Pressure Drop as your calculation type, the 
pipe schedule is automatically set as None.
Diameter If you selected Pressure Drop as your calculation type, then 
you have to enter a value for the pipe’s actual inner 
diameter. HYSYS then calculates the pressure drop.
Pressure 
Drop
If you selected Max. Diameter as your calculation type, 
then you have to enter a value for the pressure drop. 
HYSYS then calculates the pipe’s actual inner diameter.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-174
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Th14.15.2 Performance Tab
You can examine the results of the pipe sizing utility on the 
Results page of the Performance tab.
 Figure 14.10014-175
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14-176 Property Balance Utility
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Th14.16 Property Balance 
Utility
The Property Balance Utility allows you to inspect material and 
energy balances across the entire flowsheet or across selected 
operations. The Property Balance utility property view contains a 
Name field, a Scope Object button, a Delete button, a Refresh 
Scope Objects button, a Close button, and two tabs: Material 
Balance and Energy Balance.
When you open the Property Balance Utility, the values are 
automatically calculated. However, when you make topology 
changes to the flowsheet, this utility is not automatically 
updated. To update this page, use the Refresh Scope Objects 
button.
Selecting Scope for Balance 
Calculations
Click the Scope Object button to select what operations you 
want to perform your material or energy balance calculation 
over. The Target Objects property view appears.
The Target Objects property view contains two groups and three 
 Figure 14.101
To add the Property 
Balance utility, refer to 
the section on Adding a 
Utility.14-176
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Thsub groups.
The Objects Available group contains tools to help you select the 
objects you want to perform the balance calculation over. 
Generalized Procedure for Selecting Objects
1. Select the flowsheet containing the objects you want from 
the FlowSheets group. Use the Object Filter radio buttons to 
help narrow your search.
2. Select the objects you want from the object list in the 
Objects Available group.
Use the SHIFT or CTRL keys to select more than one object 
from the list.
3. Click the  button to move the selected objects from 
the Objects Available group to the Scope Objects group.
You can remove objects from the Scope Objects group by 
selecting the objects you do not want from the list, and 
clicking the  button.
To perform a material or energy balance over the entire 
flowsheet, you have to select all the operations in the 
flowsheet. You can also perform a material or energy 
balance over the entire main flowsheet by selecting the 
FlowSheet Wide radio button in the Object Filter group, and 
adding the FlowSheet Wide variable from the FlowSheet 
Wide group.
 Figure 14.10214-177
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14-178 Property Balance Utility
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Th4. Once you have added all the objects you want in the Scope 
Objects group, click the Accept List button.
Click the Cancel Changes button to exit the Target Objects 
property view without making any changes. 
5. After clicking the Accept List or Cancel Changes button, 
you return to the Property Balance utility property view. 
6. If you selected one object for balance calculation, the field 
beside the Scope Objects button displays the name of the 
object. If you had selected more than one object, the field 
displays the words Multi Hook. This indicates that more 
than one object was selected.
14.16.1 Material Balance Tab
The Material Balance Tab contains two radio buttons that control 
the property view in the tab:
• Setup
• Balance Results
Setup Radio Button
The utility generates a balance on any stream property or 
combination of stream properties you select. You can set up 
multiple balances and view results of each balance in turn. On 
the Setup property view, you define the stream properties of 
interest (the variables), and the relationships between them 
 Figure 14.10314-178
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Th(the formulas).
 Figure 14.10414-179
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14-180 Property Balance Utility
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ThThe following table contains the description of the objects in the 
Setup property view.
Objects Description
Insert Variable Allows you to insert a variable to the balance 
calculation. The variable you selected appears in the 
Variable column.
Remove Variable Allows you to remove a variable from the table, select 
the variable you want to remove and click this button
Variable column Displays the name of the variable you added to the 
balance calculation. The name is based off the text 
entered in the Description field from the Variable 
Navigator property view.
Alias column Displays the name designated to the variable by 
HYSYS. The designated name is used to represent the 
variable when entering a formula equation.
Insert Formula Allows you to insert a space for a formula in the 
formula table.
Remove Formula Allows you to remove a formula from the table, select 
the formula you want to delete and click this button.
Formula column Allows you to enter a formula equation.
Alias column The column displays the name designated to the 
created formula by HYSYS. The designated name is 
used to represent the formula when entering a formula 
equation.
Description 
column
Allows you to enter a description about the formula.
Variable Type 
column
You can select the variable unit type for the calculated 
result of the formula in this column. The variable types 
available are contained in the drop-down list.
HYSYS automatically assigns variable unit types to 
simple formula. An example is a formula with a 
temperature variable being multiplied by 2, HYSYS 
assigns Temperature as the formula’s variable unit 
type.14-180
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ThAdding a Variable
To add a variable:
1. In the Property Balance Utility view, click Insert Variable or 
double-click the <> cell. The Variable 
Navigator property view appears.
2. Select the Variable and Variable Specifics from the lists.
You cannot add the following variables from the Variable list:
3. Click OK to return to the Property Balance Utility view. 
Notice that the variable you added appears in the variable 
table.
Changing a variable
To change an existing variable:
1. In the Property Balance Utility view, double-click the variable 
cell you want to change. The Variable Navigator appears.
2. Select the new Variable and Variable Specifics from the lists. 
Variable Specifics might not be available for every Variable.
3. To change the description of the variable, type the new 
description in the Description field.
4. Click OK.
Adding a Formula
To add a formula:
1. Click the Insert Formula button, an empty row for the 
• Heat Flow
• Molar Enthalpy
• Mass Enthalpy
• Molar Entropy
• Mass Entropy
• Phase Enthalpy
• Phase Entropy
• Phase Heat Flow14-181
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14-182 Property Balance Utility
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Thformula appears in the formula table.
You can also enter a new formula by entering the formula in 
the <> cell.
The Insert Formula button can be used to insert a formula in 
between a list of formulas.
2. Enter a formula equation in the Formula cell. To manipulate 
any of the variables from the variable list, you have to use 
the names of the variables from the Alias column.   
To view the syntax available in HYSYS, add a spreadsheet to 
the PFD, open the spreadsheet property view, and click the 
Function Help button.
3. You can change the Description of the formula by entering a 
new description in the Description cell. HYSYS sets a default 
description of the word Formula and the number designated 
to the formula. You can also select a variable type for the 
formula results. HYSYS default selection for the variable type 
is Unitless.
You can also enter a formula containing another formula. An 
example is the table containing both formulas, f0 = v0-1 and 
 Figure 14.105
 Figure 14.106
The formulae follow the same syntax as the spreadsheet.14-182
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Thf1 = f0*10. So formula f1 contains another formula f0.
Setting up a Property Balance
Suppose you want to look at the sulfur balance across a group of 
objects, and you are using refinery assays. You can do the 
following:
1. Add a Mass Flow variable (v0).
2. Add a Sulfur Content variable (v1). 
This variable is located by selecting Calculator in the 
Variable list and Sulfur Content in the Variable Specifics list 
from the Variable Navigator property view.
3. Add a formula of v0*v1/100 to get the mass flow of sulfur.
4. View the results of this formula by selecting the Balance 
Results radio button, and selecting the formula from the 
Balance Type drop-down list.
 Figure 14.107
 Figure 14.10814-183
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14-184 Property Balance Utility
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ThBalance Results Radio Button
You can view the results of the selected variables and formula 
by selecting the Balance Results radio button.
The following table contains the description of each object on 
the tab when you select the Balance Results radio button.
 Figure 14.109
Object Description
Balance Type You can select the type of balance you want to see 
from the drop-down list. The type of balance comes 
from the variables you added and formulas you created 
when the Setup radio button was selected.
Inlet Material 
Stream column
Displays all the inlet streams considered for the 
balance calculation. 
If you selected one operation, then the inlet streams 
for that particular operation is considered. 
If you selected all the operations in the flowsheet, only 
the Feed Block streams are considered. 
Outlet Material 
Stream column
Displays all the outlet streams considered for the 
balance calculation. 
If you selected one operation, then the outlet streams 
for that particular operation is considered. 
If you selected all the operations in the flowsheet, only 
the Product Block streams are considered. 
Refer to Section 12.2.3 
- Dynamics Tab for 
more information 
regarding Feed Block 
and Product Block 
streams.14-184
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Th14.16.2 Energy Balance Tab
The Energy Balance tab displays the energy balance results 
across the operations you selected in the Targets Object 
property view.
Counted column You can indicate which stream you do not want in the 
balance calculation by clearing the checkbox of the 
associated stream in this column. The default setting 
for the checkbox is active.
Values column Displays the value of the variable for the associated 
stream. The variable is the selected variable from the 
Balance Type drop-down list.
Total of Inlet 
Stream
Displays the sum of the values in the Value column for 
the inlet streams.
Total of Outlet 
Stream
Displays the sum of the values in the Value column for 
the outlet streams.
Imbalance Displays the result of subtracting the total inlet stream 
value from the total outlet stream value. 
Relative 
Imbalance
Displays the percentage result of dividing the 
imbalance value by the total inlet stream value and 
multiplying that value by 100.
 Figure 14.110
Object Description14-185
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14-186 Property Balance Utility
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ThThe table below contains the description of the objects on the 
Energy Balance tab.
Object Description
Inlet Stream 
column
Displays all the inlet streams considered for the 
balance calculation. If you selected one operation, then 
the inlet streams for that particular operation is 
considered. If you selected all the operations in the 
flowsheet, only the Feed Block streams are considered. 
Outlet Stream 
column
Displays all the outlet streams considered for the 
balance calculation. If you selected one operation, then 
the outlet streams for that particular operation is 
considered. If you selected all the operations in the 
flowsheet, only the Product Block streams are 
considered. 
Counted column You can indicate which stream you do not want in the 
balance calculation by clearing the checkbox of the 
associated stream in this column. The default setting 
for the checkbox of all the stream is active.
Values column Displays the heat flow value of the associated stream. 
Total of Inlet 
Stream
Displays the sum of the values in the Value column for 
the inlet streams.
Total of Outlet 
Stream
Displays the sum of the values in the Value column for 
the outlet streams.
Imbalance Displays the result of subtracting the total inlet stream 
value from the total outlet stream value. 
Relative 
Imbalance
Displays the percentage result of dividing the 
imbalance value by the total inlet stream value and 
multiplying that value by 100.
Refer to Section 12.2.3 
- Dynamics Tab for 
more information 
regarding Feed Block 
and Product Block 
streams.14-186
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Utilities 14-187
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Th14.17 Property Table
The Property Table utility allows you to examine property trends 
over a range of conditions in both tabular and graphical formats. 
Using a stream of known composition, you can target two 
independent variables and their respective ranges of interest. 
The range of each independent variable is distinct, and can be 
set as either an incremental range or a selection of specific 
values. Next, you can relate which dependent variables are to 
be displayed at each combination of the independent variables.
 Figure 14.111
To add the Property 
Table utility, refer to the 
section on Adding a 
Utility.14-187
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14-188 Property Table
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Th14.17.1 Design Tab
The Design tab contains the following pages:
• Connections
• Dep. Prop
• Notes
Connections Page
On the Connections page, you can select the stream, the two 
independent properties, the range of values, and increments 
you want the utility to display.
Independent Variables
The following are the general steps required to set the 
independent variables.
1. On the Design page, click the Connections page.
2. Click the Select Stream button, and the Select Process 
Stream property view appears.
3. Select a stream for the analysis from the Object list.
4. Click the OK button to return to the Connections page.
 Figure 14.11214-188
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Th5. On the Connections page, identify one or two independent 
variables in the Variable 1 and Variable 2 (if desired) input 
cells. The options include:
• Pressure
• Temperature
• Vapour Fraction
• Enthalpy
• Entropy
6. Next, you can select the Mode for the independent 
variable(s). There are two options:
• Incremental. The input required includes the number of 
increments, and values for the upper and lower bounds. 
The dependent variable(s) are calculated at each 
increment within the range.
• State. You can input an unlimited number of specific 
values for the independent variable in the State Values 
matrix.
For the incremental variable(s), specify an upper bound, a lower 
bound, and the number of increments.
One of the independent variables must be either Pressure or 
Temperature. If the first variable selected is not 
Temperature or Pressure, the drop-down list for the second 
variable can be limited to Temperature, Pressure and Not 
Set. 
 Figure 14.11314-189
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14-190 Property Table
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ThNext, you need to specify the dependent property as stated in 
the red status bar.
Dep. Prop Page
On the Dep. Prop page, you can select the dependent variable.
Dependent Variables
The following are the general steps required to set the 
dependent variables.
1. On the Design page, click the Dep. Prop page.
2. Click the Add button, and the Variable Navigator property 
view appears.
3. Select a stream for the analysis from the Object list.
 Figure 14.11414-190
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Th4. Click the OK button to return to the Dep. Prop page. 
5. Repeat steps #2 to #4 to add more dependent variables.
6. Click the Calculate button once you’ve added all your 
variables.
 Figure 14.115
You can change the dependent variable by selecting the 
variable from the list and clicking the Edit button.
You can remove the dependent variable from the list by 
selecting the variable, and clicking the Delete button.
 Figure 14.11614-191
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14-192 Property Table
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ThThe Calculate button is located at the bottom of the 
property view. The Calculate button is only available when:
• HYSYS has not calculated the values for the Property 
Table.
• You have selected a stream, independent variable and 
dependent variable.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.17.2 Performance Tab
You can examine the results of the property table utility in the 
pages on the Performance tab. The Performance tab contains 
the following pages:
• Table
• Plots
Table Page
A table listing the results of the property table calculations can 
be viewed on the Table page. This page lists the independent 
variables, the dependent variables, and the phases present at 
the given conditions.
The phase column indicates the phases, which have been 
detected at each pair of independent property values. The V 
indicates vapour, L indicates a light liquid (hydrocarbon rich) 
phase, and H indicates the presence of a heavy liquid (aqueous) 
phase.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-192
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ThPlots Page
The Plots page allows you to display the results of the Property 
Table utility calculations in a graphical format. 
You can select which dependent variable you want to display on 
the y-variable by selecting it in the Y Variable group. 
 Figure 14.117
 Figure 14.11814-193
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ThClick the View Plot button to display the plot. 
To make changes to the plot appearance, right-click in the plot 
area and select Graph Control command from the object 
inspect menu to access the Graph Control Property View.
 Figure 14.11914-194
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Th14.17.3 Dynamics Tab
The Dynamics tab allows you to control how often the utility 
gets calculated when running in Dynamic mode.
The Control Period field is used to specify the frequency that the 
utility is calculated. A value of 10 indicates that the utility be 
recalculated every 10th pressure flow step. This can help speed 
up your dynamic simulation since utilities can require some time 
to calculate.
The Use Default Periods checkbox allows you to set the 
control period of one utility to equal the control period of any 
other utilities that you have in the simulation. For example, if 
you have five utilities and require them all to have a control 
period of 5 and currently the value is 8, with this checkbox 
selected if you change the value in one utility all the other 
utilities change. Alternatively, if you want all the utilities to have 
different values you would clear this checkbox.
The Enable in Dynamics checkbox is used to activate this 
feature for use in Dynamic mode.
 Figure 14.12014-195
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14-196 Tray Sizing
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Th14.18 Tray Sizing
With the Tray Sizing utility you can perform design mode or 
rating mode calculations on part or all of a converged column. 
Packing or tray information can be specified relating to specific 
tower internals such as tray dimensions or packing sizes, design 
flooding, and pressure drop specifications. Results include 
column diameter, pressure drop, flooding, tray dimensions, and 
so forth. 
In Design mode, HYSYS allows you to perform a design sizing 
 Figure 14.121
The Tray Sizing utility is only available for columns with 
vapour-liquid flows. This utility cannot be used to size the 
Liquid-Liquid Extractor.
The Tray Sizing utility must correspond to a single column 
flowsheet tray section.
You can set the default parameters for the Tray Sizing utility 
from the Session Preferences property view (from the Tools 
menu, select Preferences). On the Tray Sizing tab, the 
defaults for auto section parameters, trayed section, and 
packed section setups can be set.
To add the Tray Sizing 
utility, refer to the 
section on Adding a 
Utility.14-196
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Thbased on the vapour and liquid traffic in the column. Available 
design specifications in Design mode include:
• For trayed and packed type sections:
- Type of column internal parameters
- Maximum allowable pressure drop 
- Maximum allowable flooding
• For trayed type sections: 
- Maximum allowable downcomer backup
- Maximum allowable weir loading
- Various other tray parameters
In Rating mode, HYSYS allows you to perform rating calculations 
based on a specified column diameter and fixed tray 
configuration. If desired, some of the tray dimensions can be left 
unspecified and HYSYS automatically calculate design values for 
them. 
Available design specifications in Rating mode include:
• For trayed sections:
- Number of flow paths (NFPs)
- Column diameter
- Downcomer widths
• For packed sections: 
- Section diameter
- Tray for Properties
If you modify the variables in the Main Flowsheet or Column 
subflowsheet, the tray sizing utility redesigns and rerates all 
of the sections based on the current configuration using the 
new stage by stage traffic, physical, and transport property 
information from the Column subflowsheet.14-197
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Th14.18.1  Design Tab
The Design tab contains the following pages: 
• Setup. Manages the column sizing sections.
• Specs. Calculation mode and common tower sizing 
parameters.
• Tray Interval. Detailed internal specifications.
• Notes. A text editor within the utility for you to enter 
notes.
Setup Page
On the Setup page, you can select which column you want the 
tray sizing utility to calculate. This page contains several fields 
and a group. 
HYSYS allows you to create multiple stage sections so that you 
can compare column configurations with different internal types. 
 Figure 14.122
You can change the name of the utility on the Setup page, by 
entering a new name in the Name field.14-198
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ThTherefore, a given span of tray section stages can be sized more 
than once within a single Tray Sizing utility. However, a give 
stage cannot be included in more than one active section.
Selecting the Column Trays
To select the column trays for sizing:
1. On the Design tab, click the Setup page.
2. Click the Select TS button. The Select Tray Section property 
view appears.
3. Select the column and trays from the Flowsheet list and 
Object list. 
4. Click OK. You return to the Setup page.
Next, the tray section for which the sizing is desired has to be 
specified before starting any calculations. HYSYS automatically 
groups the column trays into sections, or you can add and 
define your own sections for the column.
You can make a section active by selecting the Active 
checkbox for the selected section.
 Figure 14.12314-199
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14-200 Tray Sizing
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ThSetup Sections Group
The Setup Sections group contains the options you need to 
generate tray sections. There is a table and four buttons in the 
group. The table contains options for you to use in manipulating 
the tray section and the calculation method. The four buttons at 
the bottom of the table allow you to manipulate the number of 
tray sections attached to the utility.
The following table contains a description of each option in the 
Setup Sections table.
The buttons on the Setup Sections group remain greyed-out 
until a column is attached to the utility.
Row Description
Section 
Name
Displays the name HYSYS designates to each tray section 
generated. You can change the tray section name in this 
field.
Start Displays the starting stage of the tray section. You can 
change the tray/stage using the drop-down list.
End Displays the stage where the tray section ends. You can 
change the tray/stage using the drop-down list.
Internals You can select one of the following tray types for each tray 
section:
• Sieve
• Valve
• Packed
• Bubble Cap14-200
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ThPacked Sections 
For the Packed type sections, Robbins or Sherwood-Leva-
Eckert (SLE) design correlations are used in the calculation 
for predicting pressure drop and liquid hold-up in the trays. 
On the Specs page, you can select Robbins or SLE for the 
Packing Correlation (Perry’s Chemical Engineer’s 
Handbook, 4, Seventh Edition, 1977). The rest of the 
section internal parameters can be specified on the Specs 
and Tray Internals pages of the Design tab.
Trayed Sections 
For the Trayed types sections (sieve, valve, or bubble cap), 
some of the tray configuration parameters are common to 
all tray types, and some are unique for each individual tray 
type. The internal parameters can be specified on the 
Specs and Tray Internals pages of the Design tab.
Each of the tray types uses a different calculation method:
• Valve tray calculations are based on the Glitsch, Koch, 
and Nutter valve tray design manuals (Handbook of 
Chemical Engineering Calculations, by Nicholas P. 
Chopey, McGraw Hill). 
• Sieve tray calculations are based on the valve tray 
manuals for tray layout, and Mass-Transfer Operations 
by Treybal (McGraw-Hill) for pressure drop, weeping, 
and entrainment calculations.
• Bubble tray calculations are based on the method 
described in Design of Equilibrium Stage Processes by 
Bufford D. Smith (Wiley & Sons).
Mode The tray sizing utility has two calculation modes:
• Design 
• Rating
You can only change the calculation mode on the Specs 
page of the Design tab. On the Setup page, the mode is 
view-only.
Row Description14-201
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14-202 Tray Sizing
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ThActive When this checkbox is selected for the tray section, the 
values calculated in the tray sizing utility are applied to the 
column calculations in the simulation case. More than one 
section can be active in a tray sizing utility. However, the 
same stage cannot be included in more than one active 
section.
Before updating the column flowsheet with the information 
from the tray sizing utility, you must change the default 
arrangement of the pressure profile information in the 
Column subflowsheet. 
1. In the Column Runner property view, on the 
Parameters tab, click the Profiles page. 
2. The top and bottom stage pressures must be specified 
instead of the condenser and reboiler pressures. The 
condenser and reboiler delta P specifications do not need 
to be changed. 
3. Run the column and then return to the utility.
4. In the Tray Sizing Utility property view, on the Design 
tab, click the Setup page.
5. Activate those calculated column sections that you want 
to use in your simulation. 
6. Proceed to the Performance tab, and click on the 
Results page.
7. Click the Export Pressures button, which export the 
pressure information to the column runner.
If your column is in a recycle, there is no automatic update 
of the pressure profile, it must be done manually.
Status Indicates the status of the tray sizing calculation. The 
status read either Complete or Incomplete on a section by 
section basis.
Design Limit Indicates the design specification that was the last to be 
satisfied. The five design specifications are:
• Minimum diameter
• Pressure drop
• Flooding
• Weir loading (trayed types only)
• Downcomer backup (trayed types only)
The design specification that is listed in the Design Limit 
specification field is the critical design specification that is 
closest to being exceeded if the column is sized any 
smaller. For trayed types, HYSYS uses individual design 
limits for the required active area and the required 
downcomer area design calculations.
Limiting 
Stage
Indicates the stage in the sizing section on which the 
design hinges. It is the stage that is closest to exceeding 
the design specifications limits.
For trayed towers, there are two limiting trays: the tray 
that is closest to exceeding the design specification while 
satisfying the section’s active area needs, and the tray that 
satisfies the downcomer area.
Row Description14-202
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ThThe option buttons below the table below are:
• Add Section
• Copy Section
• Auto Section
• Remove Section
Procedures for using these buttons are described in the 
following sections.
Adding Tray Sections
When using the Add Section button, HYSYS adds a new tray 
section covering the entire span of the column as the default 
size. This can be changed to a shorter span, if desired, by 
changing the start and end stages. A preliminary design 
calculation is automatically performed using all HYSYS default 
sizing parameters.
To manually add tray sections:
1. Select the column trays you want to size.
2. Click the Add Section button. 
You can add more than one section by clicking the Add 
Section button again. Depending on the type of column you 
have, HYSYS displays warning property views that 
recommend what type of tray you should use for the 
column.
3. A section appears in the Setup Sections group. 
 Figure 14.12414-203
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14-204 Tray Sizing
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Th4. The information displayed in the Setup Sections group are 
default values HYSYS provides. You can change the 
information to suit your scenario.
Using Auto Section
The Auto Section feature in HYSYS provides a good starting 
point for the tray section analysis. The feature creates tower 
sections of constant diameter based on the parameters you 
specified.
The following steps shows you how to attach the main tray 
section to the utility and use the Auto Section functionality to 
divide the column into sections:
1. Select the column trays you want to size.
2. Click the Auto Section button. The Auto Section 
Information property view appears.
3. In the Internal Type group, select the type of tray the 
column contains using the radio buttons.
4. In the Area Tolerance and NFP Diameter Factor group, 
HYSYS provides default values for area tolerance and NFP 
diameter factor. You can also enter the value you want in the 
field provided. 
 Figure 14.125
Refer to Section 
14.18.4 - Auto 
Section for more 
information about the 
Auto Section feature.14-204
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Th5. Click the Next button. The Auto Section Information 
property view closes, and the Tray Section Information 
property view appears.
6. You can specify more details about the tray type in the group 
below the radio buttons. The group’s name depends on 
which tray type your select.
7. In the Common Tray Properties group, you can specify the 
values for tray spacing, tray thickness, tray foaming factor, 
maximum tray dP, and maximum tray flooding.
8. In the DC/Weir Info group, you can specify the information 
for weir height, maximum weir loading, downcomer type, 
downcomer clearance, and maximum DC backup.
9. Click the Complete AutoSection button, when you are 
done editing the tray section information. HYSYS proceeds 
with the Auto Section calculations. 
 Figure 14.12614-205
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14-206 Tray Sizing
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Th10.The Tray Section Information property view automatically 
closes, and you return to the Setup page of the Tray Sizing 
utility property view. 
Copying a Tray Section
To copy a section perform the following steps:
1. Select the section you want to copy from the Setup Sections 
group.
2. Click the Copy Section button. 
3. A copy of the selected section appears in the table.
Removing a Tray Section
To remove a section perform the following steps:
1. Select the section you want to remove from the Setup 
Sections group.
2. Click the Remove Section button. 
3. HYSYS removes the selected section from the Setup Sections 
group.
 Figure 14.12714-206
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ThSpecifying % Liquid Draw and Tray Vapour 
Sizing
At the bottom of the Setup page, there are two fields:
• % Liquid Draw. The % Liquid Draw field allows you to 
specify the percentage of side liquid draws to be used in 
the tray sizing calculations. When you specify a liquid 
percent, HYSYS assumes that your specified draw 
percentage is sitting on the tray. 
- The default value of 0% means that no additional 
liquid is assumed to be on the tray.
- If you enter 100%, flooding increases because you 
have an additional volume of liquid equal to the draw 
rate sitting on the tray.
The percentage value can be equivalent for all trays with 
draws. You cannot specify different percentages for 
different draws on different trays.
•  Use Tray Vapour to Size. If you have vapour feed(s) 
attached to your column, HYSYS can size the particular 
tray (which is attached to the vapour feed) using the 
vapour feed flowing into the tray section or the vapour 
flow leaving the tray. The Use Tray Vapour to Size field 
contains a drop-down list of the methods available in 
HYSYS:
- Always Yes. HYSYS uses the vapour flow leaving the 
tray section to size the tray for all calculations. The 
effect of the feed on the tray sizing is considered in 
the calculation. This method generates results that 
closely represent reality. If you have a vapour feed to 
your column, you can choose which tray the feed 
vapour is taken into account in the sizing/flooding 
calculations. For example, if you have a vapour feed 
to tray 22 and you select Always Yes, HYSYS takes 
the vapour feed and assumes that it is in equilibrium 
with the vapour underneath tray 22. The vapour feed 
plus the vapour from tray 23 are used in sizing tray 
22.
- Always No. HYSYS uses the vapour feed to the 
section to size the tray for all calculations. The effect 
of the feed is not considered for this method. For 
example, if you have a vapour feed to tray 22 and 
you select Always No, HYSYS assumes that the 
vapour feed is in equilibrium with the vapour leaving 
tray 22. The assumed vapour feed is used in the 
sizing calculations from Tray 21.
- Ask Each Time. Prior to calculating the Tray Sizing 
utility, HYSYS asks you to specify whether to use feed 
to the tray or vapour flow from the tray as a basis. A 14-207
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14-208 Tray Sizing
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Thmessage appears for each vapour feed to your 
column prior to the calculations, as shown the in the 
figure below:
T
Specs Page
The Specs page allows you to specify the column internals for 
each section.The options are arranged in a tabular format.
 Figure 14.128
The selection of method in the Use Tray Vapour to Size drop-
down list affects all trays, regardless of whether they have a 
vapour feed or even any feed at all. The difference in method 
is its selection of the vapour that comes from the tray below 
or the vapour that leaves the tray as a basis for sizing 
calculations. 
 Figure 14.12914-208
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ThThe following tables outline the available design and tray 
configuration parameters applicable to the Trayed or Packed 
type column for the sizing calculation:
Design Parameters
Tray Configuration Parameters
Parameter Trayed Packed 
Design Correlation X
Foaming Factor X X
Flooding X X
Pressure Drop X X
Downcomer Backup X
Weir Loading X
Parameter Valve Sieve Bubble
Number of Flow Paths X X X
Tray Spacing X X X
Tray Thickness X X X
Weir Height X X X
Downcomer Type X X X
Downcomer Clearance X X X
Design Manual X
Hole Area X X
Hole Diameter X
Hole Spacing X
Hole Pitch X
Valve Density X
Valve Thickness X
Orifice Type X
Bubble Cap Slot Height X14-209
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ThGeneral Parameters
The Section Name, Start Tray, End Trays, Internals, and 
Mode from the table on the Specs page are the same 
parameters as in the Setup page. However, you are only able to 
change the calculation mode for the section on the Specs page. 
The Sieve Tray Flooding Method drop-down list enables you 
to select the model used to simulate flooding in a Sieve type 
tray. HYSYS provides the following models: 
• Minimum Csb
• Original Csb
• Fair’s Modified Csb
The Section Property Mode drop-down list enables you to 
select the start tray for the Property Mode calculations. HYSYS 
provides two selections:
• The First Tray in Section option applies to a column 
with multiple sections and each section has different 
Property Mode calculations.
• The First Tray in Column option applies to a column 
with single or multiple sections and only one type of 
Property Mode calculation is applied to the whole column.
The following sections describe in detail the parameters 
available in the Tray Sizing utility and the default values that 
HYSYS provides.
Number of Flow Paths
The Number of Flow Paths (NFP) value represents the 
number of independent flow paths per tray. Usually a smaller 
tower diameter can be obtained by using multi-pass trays. 
However, with more flow paths, there is a reduction in the 
number of valves or sieve holes that can be placed on the tray. 
This can result in an increase in the pressure drop, an increase 
in downcomer backup, and a loss in tray efficiency. 
In Design mode, the NFP value is calculated if you do not 
specify the value. In Rating mode, you must specify the NFP 
value.14-210
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Utilities 14-211
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ThThe following are general guidelines relating the number of flow 
paths and the tower diameter:
If the NFP is not specified, HYSYS starts at one pass and 
increases the number of passes until the minimum diameter for 
that NFP is reached. If a smaller NFP is required, a new value 
can be entered that overrides the calculated NFP. A new solution 
is calculated as soon as the new NFP is entered.
The figure below summarizes the basic physical layouts of the 
flow paths available.
Number of Passes Min. Diameter (ft) Pref. Diameter (ft)
2 5 6
3 8 9
4 10 12
5 13 15
 Figure 14.13014-211
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14-212 Tray Sizing
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ThSection Diameter
The Section Diameter value is the diameter of the tray section 
based on the NFP calculated or specified.
Tray for Properties
The Tray for Properties variable enables you to select the tray 
upon which the property calculation for the column will be 
based.
Tray Spacing
The tray spacing is the vertical distance between trays. Some 
general guidelines for tray spacing follow:
The default value is 24 inches.
In Design mode, the Section Diameter is calculated. In 
Rating mode, you must specify the Section Diameter value.
The Tray for Properties variable is only applicable for Packed 
type columns. The variable can only be manipulated in 
Rating mode.
Expected Tower Diameter (ft) Suggested tray Spacing (in)
--- 12 (minimum)
Up to 4 18 - 20
4 - 10 24
10 - 12 30
12 -24 3614-212
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Utilities 14-213
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ThValve and Tray Material Thickness
Since material thickness is often described in terms of gauge, 
the following table is provided for quick conversions between 
gauge and thickness in inches:
The default tray thickness is 0.125 inches.
Foaming Factor
Foaming refers to the expansion of liquid due to passage of 
vapour or gas. Foaming Factor is a measure of the foaming 
tendency of the system. In general, a lower foaming factor 
results in a lower overall tray efficiency and requirements for a 
larger column diameter. The default foaming factor value is 1. 
Foaming factors typically seen in some common systems include 
the following:
Gauge Thickness (in)
20 0.037
18 0.050
16 0.060
14 0.074
12 0.104
10 0.134
General Foaming Classification Foaming Factor
Non Foaming Systems 1.00
Low Foaming Tendencies 0.90
Moderate Foaming Tendencies 0.75
High Foaming Tendencies 0.6
Absorbers Foaming Factor
Ambient Oil (T > 0°F) 0.85
Low Temp Oil (T < 0°F) 0.95
DGA/DEA/MEA Contactor 0.75
Glycol Contactor 0.65
Sulfinol Contactor 1.014-213
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ThMax Delta P (Maximum Pressure Drop)
The maximum allowable pressure drop per tray can be entered 
as a height of liquid.
If the variable value is not specified: 
• For trayed type section, a default maximum of 4 inches 
of liquid is used.
• For packed type section, a default specification is 0.5 
inches of water per foot of packing is used.
In packed type section, the specified variable value is applied on 
a pressure drop per height of packing basis.
Maximum Flooding
Flooding is brought about by excessive vapour flow, causing 
liquid to be extrained in the vapour flowing up the column. 
HYSYS will size the column so that for the given vapour and 
liquid traffic, the tower flooding does not exceed the specified 
Max Flooding variable on any stage.
Crude/Vacuum Tower Foaming Factor
Crude or Vacuum Fractionation 1.00
Fractionators Foaming Factor
Hydrocarbon 1.00
Low MW Alcohols 1.00
Rich Oil DeC1 or DeC2 (top) 0.85
Rich Oil DeC1 or DeC2 (Btm) 1.0
Refrigerated DeC1 or DeC2 (top) 0.80
Refrigerated DeC1 or DeC2 (btm) 1.00
General Hydrocarbon Distillation 1.00
MEA/DEA Still 0.85
Glycol/DGA Still 0.80
Sulfinol Still 1.00
H2S Stripper 0.90
Sour Water Stripper 0.50 - 0.70
O2 Stripper 1.0014-214
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ThThe maximum recommended value is 85% for normal service 
and 77% for vacuum or low pressure drop applications. The 
recommended percentage values yield approximately 10% 
entrainment.
For column diameters under 36 inches, a reduced flooding 
specification of 65-75% should be used. A lower value can be 
specified to allow for contingencies, such as increased capacity.. 
Packing Correlation
Packing Correlation specification has two options.
• The Robbins correlation is valid only at loading factors < 
20000 (liquid loading < 9200 lb/hr.ft2). This correlation, 
which is the default selection, is noted to be better at 
predicting pressure drop and liquid holdup, particularly 
with newer packing materials.
• The SLE (Sherwood-Leva-Eckert) correlation is valid for 
towers operating above the loading factors of 20000 
(liquid loading > 9200 lb/hr.ft2).
HETP
The height factor HETP relates to packed towers. The value 
refers to the height of packing that is equivalent to a theoretical 
plate. For design purposes, the most accurate HETP factors are 
those published by packing manufacturers.
If not specified, a maximum flooding factor of 82% is used 
for flat orifice trays and 77% for venturi orifice trays.
The default values are provided for all packing parameters 
with the exception of the packing type and the packed 
column diameter.14-215
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14-216 Tray Sizing
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ThPacking Type
The Packing Type variable refers to the material used in the 
packing towers. A list of the available packing types is shown in 
the following table.
Packing Type Material Packing Type Material
Ballast Rings M,P Jaeger_VSP_SS M
Ballast Plus Rings M Koch-Sulzer(BX) Structured S
Ballast Saddles P Lessing Experimental M
Berl Saddles C Levapacking P
Cascade MiniRing M,P,C Maspak P
Chempak M Montz A-2 Structured S
Flexipac Mellapac S Neo-Kloss Structured S
Flexirings M Norton Intalox Metal Tower Packing M
Gempak S Nutter Rings M
Glitsch Grid S Pall Rings M,P
Goodloe S Protruded M
Wire Coil Packing M Raschig Rings 1/32 in wall CSteel
Hy-Pak Rings M Raschig Rings 1/16 in wall CSteel
Hyperfil S Raschig Rings C, Carbon
Intalox Saddles C Super Intalox Saddles P
Jaeger MaxPack SS M Tellerettes P
Jaeger Tripacks P Cross-Partition Rings C
The materials used for the different packings (unless otherwise noted) are: Metal(M), Plastic(P), Ceramic(C), 
and Metal Structured(S).14-216
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ThTray Internals Page
If the sizing section is specified as having trayed internals 
(Sieve, Valve, or Bubble Cap), then the internals can be further 
specified on the Tray Internals page. There are certain column 
parameters that are common to all trayed columns. You can 
specify these parameters or leave them at their default values.
Sieve Tray Parameters
In addition to the general Trayed type parameters, the Sieve 
tray has the following parameters:
• Sieve Hole Pitch. Hole pitch refers to the distance 
between the centers of two adjacent holes. HYSYS 
requires the hole pitch to be within 1.5 to 5 times the 
hole diameter. The default hole pitch is 0.5 inches for a 
0.187 inch diameter hole.
• Sieve Hole Diameter. The default value for the hole 
diameter is 0.187 inches.
Valve Tray Parameters
The valve tray is the default tray type for trayed columns in 
design mode. This section defines the design parameters 
specific to valve trays.
 Figure 14.13114-217
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Th• Valve Material Density. The following table lists typical 
materials used for valves and their associated densities. 
• Hole Area (% of Active Area). The hole area variable 
is the percentage of the active area that is occupied by 
the valve holes with respect to the total tray area. The 
default value is 15.3%, which corresponds to 12 valve 
holes (each having a diameter of 1 17/32 inches) per 
square foot.
• Valve Orifice Type. The Valve Orifice is the shape of the 
hole that is punched in the plate for the valve. As shown 
in the figure, there are two types of orifices: 
- Venturi. Used for low pressure drop applications.
- Straight. Used for normal service.
• Design Manual for Flooding Calculations. Results are 
presented for flooding calculations from three industry 
standard design manuals: Glitsch, Koch, or Nutter. Any 
one of the three methods can be selected as the basis for 
comparison with the maximum allowable % of flood 
design specification. The default design manual is 
Glitsch.
Valve Material Density (lb/ft3)
Carbon Steel 480
Stainless Steel 510
Nickel 553
Monel 550
Titanium 283
Hastelloy 560
The Hole Area can also be specified for Bubble Cap trays.
 Figure 14.13214-218
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ThBubble Cap Trays
• Bubble Cap Slot Height. This value represents the 
height of the slots around the base of the bubble caps, 
through which the gas and liquid are allowed to flow. The 
default slot height is 1.0 inch.
• Hole Area (% of Active Area). The hole area variable 
is the percentage of the active area that is occupied by 
the bubble cap holes with respect to the total tray area. 
The default hole area is 15.3%, which corresponds to 12 
bubble caps (each having a diameter of 1 17/32 inches) 
per square foot.
Common Tray Parameters
• Side Weir Type. A weir on the tray ensures that the 
liquid (holdup) on the tray is at a suitable height. This 
parameter is used to specify the side weir type only. 
There are two types of weirs available: straight and 
relief. 
- A relief weir lengthens the side weir without 
increasing the downcomer area. The relief weir 
sweeps back, then across the tray, enclosing some 
active area, as shown in the figure. A relief weir is 
used for high liquid loads or where a low pressure 
drop is required.
 Figure 14.13314-219
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Th- A straight weir follows the edge of the downcomer 
and is used for normal service. HYSYS uses a straight 
weir as the default. However, if the weir loading is 
above the maximum, a relief weir can be included to 
alleviate the problem.
• Weir Height. The weir height is the distance from the 
tray to the top of the weir. A weir height of 2 inches is 
used in most applications. However, a smaller height can 
be used for low pressure drop or vacuum services. A 
larger weir height is used to obtain longer residence 
times (for example, chemical reaction services). The 
default value for weir height is 2 inches. In general, you 
can use the following standard values:
• Maximum Allowable Weir Loading. The weir loading 
is a measure of the liquid loading on the weirs. Values of 
60 - 120 USGPM/ft are typical. Weir loading may be 
reduced by increasing the number of flow paths or 
installing a relief weir. A weir loading as high as 240 
USGPM/ft can sometimes be tolerated. If the weir loading 
is not specified, a default value of 96 USGPM/ft is used.
• Downcomer Type. In the column, liquid falls from a 
tray to the one below it through the downcomers. There 
are two types of downcomers available:
- Vertical. Due to cost considerations, a vertical 
downcomer is used for normal service and is the 
default in HYSYS.
- Sloped. A sloped downcomer has a narrower width 
at the bottom. This structure allows more active area 
and more valves per tray, and it also results in a 
lower pressure drop.
• Downcomer Clearance. The downcomer clearance is 
the distance between the bottom of the downcomer and 
the tray. The area available for liquid flow under the 
downcomer is dependent upon this height. A minimum 
seal of 0.5 inches is normally recommended. For high 
liquid velocities and the resulting high pressure drop, this 
can be reduced. If the downcomer clearance is not 
specified, a height of 0.5 inches less than the weir height 
If HYSYS installs a relief weir but you want a straight weir, 
re-specify a straight weir and rerun the tray in rating mode.
Tray Spacing (in) Weir Height (in)
12 1.5
12 - 24 2
>24 2.514-220
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This used. If the weir height and downcomer clearance are 
not specified, HYSYS provides a default weir height of 2 
inches and a downcomer clearance of 1.5 inches. 
• Maximum Allowable Downcomer Backup. The 
allowable downcomer backup is measured as the 
percentage of the tray spacing that the liquid level in the 
downcomer is allowed to reach. This variable value 
represents the average for all the downcomers on the 
tray. If not specified, the following default values are 
provided by HYSYS:
- 40% for services with a vapour density greater than 3 
lb/ft3
- 50% for normal densities with a vapour density 
between 1 lb/ft3 and 3 lb/ft3
- 60% for densities less than 1 lb/ft3
Common Parameters for Rating Mode
The following tray parameters are applicable in Rating mode:
• Side DC Top Width. The top width of the downcomer 
side value is required in Rating mode calculation of the 
section’s performance.
• Side DC Bottom Width. The bottom width of the 
downcomer side value can be specified if the downcomer 
is sloped and you want a more realistic value in the 
Rating calculations.
• Centre DC Top Width. The top width of the downcomer 
centre value is required in Rating mode calculation of the 
section’s performance.
• Centre DC Bottom Width. The bottom width of the 
downcomer centre value can be specified if the 
downcomer is sloped and you want a more realistic value 
in the Rating calculations.
• O.C. DC Top Width. The top width of the downcomer 
off-centre value is required in Rating mode calculation of 
the section’s performance.
• O.C. DC Bottom Width. The bottom width of the 
downcomer off-centre value can be specified if the 
downcomer is sloped and you want a more realistic value 
in the Rating calculations.
• O.S. DC Top Width. The top width of the downcomer 
off-side value is required in Rating mode calculation of 
the section’s performance.
Refer to Column Rating 
for more information.14-221
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Th• O.S. DC Bottom Width. The bottom width of the 
downcomer off-side value can be specified if the 
downcomer is sloped and you want a more realistic value 
in the Rating calculations.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.18.2 Performance Tab
The Performance tab contains the following pages: 
• Results. Overall comparative section results and 
detailed tray sizing information.
• Trayed. Pressure Drop, Downcomer, and Flooding 
results across the column.
• Table. Tray section physical property profiles in the 
tabular form.
• Plots. Tray section physical property profiles in the 
graphical form.
Downcomer widths that are not specified can be calculated 
at optimal design values for the given number of flow paths.
When calculated widths are applied to a vertical downcomer, 
no slope is assumed.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-222
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ThResults Page
The Results page displays the specified and calculated details of 
variables and outputs in the tray section.
You can also modify the specified tray variable values in the 
Results page. Any changes will automatically be reflected in the 
appropriate pages of the Design tab. 
The Section Results group has two radio buttons: 
• Trayed. Selecting this radio button tells HYSYS to 
calculate the tray size for a tray column/tower.
• Packed. Selecting this radio button tells HYSYS to 
calculate the tray size for a packed column/tower.
Clicking the Export Pressure button signals HYSYS to take the 
calculated pressure profile and export it to the active tray 
section, thus causing the column to reconverge to the pressure 
profile predicted by the tray sizing utility. A section in the utility 
must be made active, before this option can be used.
 Figure 14.13414-223
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ThClick the View Warnings button to see any problems HYSYS 
detects in the tray section. The figure below shows two possible 
warning messages if the incorrect tray type is selected.
Trayed Page
On the Trayed page, HYSYS displays tray-by-tray information for 
the selected section. 
To display information on Pressure Drop, Downcomer, or 
Flooding, select the corresponding radio button. To view the tray 
information of a different section, use the drop down menu.
 Figure 14.135
 Figure 14.13614-224
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ThTable Page
The Table page contains two radio buttons (Vapour (to Tray) 
and Liquid (from Tray)) and a table that displays the values of 
six of column variables for each tray.
The column variables are:
• Mass Flow
• Gas/Liquid Flow
• Molecular Weight
• Temperature
• Density
• Viscosity
Select the Vapour (to Tray) radio button to view the column 
variable information for the vapour fluid in each tray.
Select the Liquid (from Tray) radio button to view the column 
variable information for the liquid fluid in each tray.
 Figure 14.13714-225
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ThPlot Page
The Plot page displays the following column variable values in a 
plot format for each tray:
• Delta P (pressure difference)
• Mole Wt (molecular weight)
• Density
• Pressure
• Flow (mass flow rate)
• Temp (temperature)
• Viscosity
• Surf Ten (surface tension) 
The plot contains one set of data for the vapour phase and one 
set of data for the liquid phase in each tray.
Select the column variable radio buttons in the Plot group to 
view the vapour and liquid data for each tray.
 Figure 14.13814-226
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Th14.18.3 Dynamics Tab
The Dynamics tab contains the Calculation page. 
The Calculation page contains only one option, Calculate Now. 
By default, the Tray Sizing utility does not perform any 
calculations in Dynamic mode. To see the calculated sizing 
results in Dynamic mode, click Calculate Now. 
14.18.4 Auto Section 
The Auto Section function is an optional method in design mode. 
When using Auto Section, HYSYS automatically calculates the 
sections for a column. The calculated variables are then 
transferred onto the main utility Setup tab where you can edit, 
copy, or delete the auto-generated sections. The Auto Section 
option gives you an excellent starting point in the design of a 
tower by performing a summary sizing of the tray section and 
splitting the column into sections of constant diameter. 
 Figure 14.13914-227
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ThWhen using the Auto Section option to generate sections, HYSYS 
allows you to specify the internal type and values for the criteria 
that are used to generate a new section. The two criteria that 
you can specify to establish tower sections are:
• Area Tolerance
The Area Tolerance defines the magnitude of change in 
the calculated area that causes the start of a new 
section. HYSYS first performs a design for stage i (using 
the current parameters for the chosen internals) and the 
number of flow path (NFP) for the current section (valve, 
sieve, and bubble trays only) to determine the required 
area. This area is compared to the minimum and 
maximum areas for the current section, which HYSYS 
retains.
If the magnitude of difference for either comparison 
exceeds the Area Tolerance variable, a new section is 
started beginning at stage i. The previous section can be 
assigned the maximum diameter for that section. If the 
calculated area for stage i is outside the range defined by 
the minimum and maximum for the section but does not 
exceed the tolerance, the calculated area for stage i 
replaces the appropriate stored value.
• NFP Diameter Factor
When the comparison of areas is complete, HYSYS 
recalculates the required area of each stage using a 
different NFPs. This area is compared with the previously 
calculated area for each stage. If the magnitude of the 
change is greater than the NFP Diameter Factor variable, 
The Auto Section option is not available until a tray section 
has been selected on the Setup tab of the tray sizing utility.14-228
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Tha new section is generated.
The entire column is stepped off in the above manner according 
to the Area and NFP guidelines. The calculated sections of 
constant diameter, NFPs, active area, and downcomer area are 
defined for the tower. When this initial sizing is complete, HYSYS 
re-rates each tray based on a diameter calculated from the 
maximum downcomer and active area required for trays in that 
section. This value is available on the Results page of the 
Performance tab of the utility property view. The limiting 
factor(s) for each section appear on the Setup tab.
When using the Auto Section option, you are required to specify 
the tray internal type, either Sieve, Valve, Bubble Cap or 
Packed. In addition, you have the option of specifying the 
parameters for the chosen configuration. If no parameters are 
specified, HYSYS uses values from its default set.
 Figure 14.14014-229
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ThColumn Rating
Column sections can be rated using the Rating calculation mode 
on the Specs page. From the Mode drop-down list, select Rating, 
as shown in the figure below.
If you modify the Main Flowsheet or Column subflowsheet, the 
tray sizing utility redesigns and rerates all of the sections based 
on the current configuration using the new stage by stage 
traffic, physical, and transport property information from the 
Column subflowsheet.
Trayed Section Rating
For trayed sections, the minimum required information for 
HYSYS to calculate the section performance includes the number 
of flow paths and the column diameter.
If desired, you can specify the following downcomer widths on 
the Tray Internals page:
• Side top and optional bottom
• Centre top and optional bottom
• Off-side top and optional bottom
• Off-centre top and optional bottom
The optional bottom width allows for the specification of sloped 
downcomers. Downcomer widths that are not specified can be 
calculated at optimal design values for the given number of flow 
paths.
The remaining tray configuration parameters can be specified as 
discussed in the Specs Page section. Once rating parameters 
have been set, HYSYS completes the rating calculations.
 Figure 14.14114-230
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ThPacked Section Rating
For packed sections, the required information for HYSYS to 
calculate the section performance includes both the Section 
Diameter and the Tray for Properties on the Tray Internals page.
The remaining tray configuration parameters can be specified as 
discussed in the Specs Page section. Once rating parameters 
have been set, HYSYS completes the rating calculations. If 
HYSYS is unable to complete the calculations, this will be 
indicated on the property view’s status bar. To view the warnings 
generated, click on the Results page of the Performance tab and 
click the View Warnings button.
14.19 User Properties
The User Property utility allows you to view User Properties (that 
you have defined) based on the composition of a stream. You 
can only add User Properties in the Basis environment. 
Possible uses of the User Property include as a specification in a 
distillation column or as a target variable in an Adjust operation.
 Figure 14.142
Refer to Chapter 7 - 
User Properties of the 
HYSYS Simulation Basis 
guide for detailed 
information concerning 
User Properties.14-231
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Th14.19.1 Design Tab
The Design tab contains the following pages:
• Connections
• Notes
Connections Page
You can specify the stream you want to attach to the utility, and 
add the properties you want on the Connections page.
You can also change the name of the utility on this page, if 
desired.
 Figure 14.143
To add the User 
Properties utility, refer 
to the section on 
Adding a Utility.
Click the View 
Formulae 
button to view 
the selected 
Mixing Rule 
formula.14-232
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ThAdding a Stream to User Properties
1. On the Design tab, click on the Connections page. 
2. Click the Select Stream button. The Select Process Stream 
property view appears.
3. Select a stream from the Object list, and click the OK 
button. You return to the Connections page.
You can disconnect a stream by clicking the Disconnect button in 
the Select Process Stream property view. 
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
14.19.2 Performance Tab
The Performance tab contains the Property Values page.
 Figure 14.144
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-233
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ThProperty Values
The Property Values page contains two tables. 
The top table contains a list of all the components in the stream. 
The bottom table contains the parameter values for the 
equations to use on the Connections page.
You can only change the parameter values of the property in the 
Basis Environment. 
 Figure 14.145
It is recommended that you leave the mixing rule equation 
parameters at their default values. 
Refer to Section 7.3.1 
- Data Tab in the 
HYSYS Simulation 
Basis guide, for 
information about the 
parameter values 
available for you to 
manipulate.14-234
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Th14.20 Vessel Sizing
The Vessel Sizing utility allows you to size and cost installed 
separator, tank, and reactor unit operations. You can select a 
vertical or horizontal orientation for the separator. To obtain a 
more effective analysis for your vessel, changes can be made to 
the default parameters provided by HYSYS. 
14.20.1 Design Tab
The Design tab allows you to select the vessel that is to be 
sized, the dimensions of the vessel, the vessel material, and the 
cost of the vessel. The tab consists of the following pages:
• Connections
• Sizing
• Construction
• Costing
• Notes
 Figure 14.146
For a comprehensive costing and sizing software package for 
your entire case, Economix is available. Contact your nearest 
AspenTech office or agent for details.
To add the Vessel Sizing 
utility, refer to the section 
on Adding a Utility.14-235
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ThConnections Page
On the Connections page, you select the vessel you want to size 
and the vessel’s orientation. You can also change the name of 
the utility on this page.
To select a vessel:
1. On the Design tab, click on the Connections page.
2. Click the Select Separator button. The Select Separator 
property view appears.
3. Select the vessel you want to size from the Object list, and 
click the OK button.
 Figure 14.147
 Figure 14.148
Clicking the Set 
Defaults button 
returns all of the 
original data 
provided by 
HYSYS.14-236
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Th4. You automatically return to the Connections page. Now 
select the orientation of the vessel using the Vertical or 
Horizontal radio button. 
Sizing Page
The Sizing page allows you to set the specification variables that 
are used to size the vessel.
To select the specification variable:
1. Select the specification variable from the Available 
Specification group.
2. Click the Add Spec button. The specification variable is 
moved into the Active Specification group.
3. HYSYS provides default values for the specification, but you 
can change the values. Enter the value you want for the 
specification variable in the cell provided.
The following is the list of available specifications that are 
specific to the orientation of the separator:
• Max. Vapour Velocity
• Diameter
• L/D Ratio
• Vapour Space Height
 Figure 14.149
If the diameter value is not specified, HYSYS automatically 
changes this value when the vessel orientation is switched.14-237
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Th• Demister Thickness
• Liquid Residence Time
• Liquid Surge Height
• Total Length - Height
• Nozzle to Demister
• Demister to Top
• LLSD (Low Level Shut Down)
• Total Separator Height
To remove the specification variable:
1. Select the specification variable you want to remove from 
the Active Specification group.
2. Click the Remove Spec button. The specification variable is 
moved back into the Available Specification group.
Construction Page
On the Construction page, you can specify any of the following 
information for the vessel:
• Chemical Engineering Index
• Material Type: Carbon Steel, SS 304, SS 316, Aluminium
• Mass Density
• FMC (material of fabrication factor)
• Allowable Stress
• Shell Thickness
• Corrosion Allowance
 Figure 14.15014-238
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ThCosting Page
You can modify the factors used in the sizing and cost equations 
on the Costing page. These factors deal with the Base Cost, 
Shell Thickness, Accessories Cost, and Shell Mass.
You can also view the results of the cost analysis on this page in 
the Costing Results group. The Base Cost, Ladders and Platform 
Cost, and Total Cost are listed in $US.
Notes Page
The Notes page provides a text editor, where you can record any 
comments or information regarding the utility, or to your 
simulation case in general.
HYSYS recalculates after each change is made on the 
Construction page.
Blue text is entered by the user, and red text is entered by 
HYSYS. You can modify the blue and red text.
 Figure 14.151
View the various 
equations by 
clicking the Cost 
Equation Help 
button.
For more information, 
refer to Section 1.3.5 - 
Notes Page/Tab.14-239
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Th14.20.2 Performance Tab
The Performance tab contains the following pages:
• Sizing Results
• Vapour Space
A summary of the sizing results and vapour space are provided 
on the each page respectively.
 Figure 14.15214-240
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Th14.21 References
 1 Marsland, R.H., “A User Guide on Process Integration for the Efficient 
Use of Energy”, Insitution of Chemical Engineers, England, 1982.
 2 Ng, H.J., Robinson, D.B., Ind Eng Chem Fund., 15, 293 (1976)
 3 Ng, H.J., Robinson, D.B., "The Measurement and Prediction of 
Hydrate Formation in Liquid Hydrocarbon-Water Systems", Ind. 
Eng. Chem. Fund.,15, 293 (1976)
 4 Ng, H.J., Robinson, D.B., AIChE J., 23, 477 (1977)
 5 Ng, H.J., Robinson, D.B., Ind Eng Chem Fundam, 19, 33 (1980).
 6 Ng, H.J., Robinson, D.B., "A Method for Predicting the Equilibrium 
Gas Phase Water Content in Gas-Hydrate Equilibrium", Ind. Eng. 
Chem. Fund.,19, 33 (1980)
 7 Overa, Sverre O., & Stange, Ellen, & Salater, “Per, Determination of 
Temperatures and Flow Rates During Depressurization and Fire”, 
presented at the 72 Annual GPA Convention, March 15-17, 1993, 
San Antonio, Texas.
 8 Parrish, W.R., Prausnitz, J.M., I.E.C. Proc Des Dev, 11, 26 (1972).
 9 Roberts, T.A., Medonos, S., Shirvill, L.C., “Review of the Response of 
Pressurised Process Vessels and Equipment to Fire Attack”, 
Offshore Technology Report - OTO 2000 051, June 2000.
 10Sloan, E.D., Khoury, F., Kobayashi, R., I.E.C. Fundam, 15, 318 
(1976).
 11Sloan,Jr.,E.D.,Clathate Hydrates of Natural Gases, Macel Dekker, 
Inc., New York, 1989.
 12van der Waals, J.H., Platteuw, J.C., Advan Chem Phys, 2, 1 (1959).14-241
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14-242 References
ww
Th14-242
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www
The I-1
Index
A
Absorber
See Column
Absorber Template (Column) 2-31
Actuator 6-173
Adiabatic Efficiency 9-37, 9-62
Adjust 5-4
individual 5-19
maximum iterations 5-14
multiple 5-19
solving methods 5-9
start 5-18
step size 5-13
tolerance 5-13
Air Cooler 4-3
duty 4-4
dynamic 4-4
dynamic specifications 4-5
holdup 4-16
pressure drop 4-5
steady state 4-3
theory 4-3
Annular Mist 6-60
Assay
curves 2-100
Assay Curves (Column) 2-100
ATV Tuning 5-282
Auto Section.
See Column Sizing Utility.
B
Baghouse Filter 11-3
parameters 11-5
sizing 11-6
Balance 5-20
general 5-26
heat 5-25
mass 5-24
mass and heat 5-26
mole 5-24
mole and heat 5-25
types 5-21
Beggs and Brill Correlation 6-57
Bnd
See also ESTIM DRU
iteration output
Boiling Point Curve Utility 14-7
BOX Method (Optimizer Operation) 7-14
Broyden Method (Adjust) 5-9
C
Central difference interval
See also ESTIM DRU
initial problem parameters
Col Dynamic Estimates 2-73
Cold Properties Utility 14-17
Cold Property Specifications (Column) 2-121
COLD start
See also ESTIM DRU
initial problem parameters
Column 2-4
3-phase detection 2-15
absorber 2-20
acceleration 2-69
advanced solving options 2-49
build environment 2-9–2-11
composition estimates 2-56–2-58
conflicting specifications 2-200
conventions 2-29
convergence 2-43
damping 2-70
design tab 2-38
dynamics tab 2-118
equilibrium error 2-62, 2-201
flowsheet tab 2-104
flowsheet variables 2-106
fluid package 2-6
heat and spec error 2-62–2-63, 2-197, 2-
200
impossible specifications 2-199
initial estimates 2-16
inner loop errors 2-194
input errors 2-198
installation 2-25
k value 2-13
operations 2-136
packed section rating 14-231
parameters tab 2-54
partial condenser 2-24
performance tab 2-91
plots 2-94
poor initial estimates 2-197
property view 2-8
rating tab 2-87
reactions tab 2-110
reboiled absorber 2-22
refluxed absorber 2-21.c
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The I-2
run / reset buttons 2-38
runner 2-37
running 2-193–2-195
See also Tray Section
side ops tab 2-82
solver 2-5
solver tolerance 2-51
specification types 2-121
specifications 2-121–2-134
stream specification 2-135
tee 2-191
theory 2-11
transfer basis 2-37, 2-105
trayed section rating 14-230
troubleshooting 2-196
worksheet tab 2-90
Column Runner 2-37–2-119
Column Sizing Utility
auto section 14-227
design 14-198
material thickness 14-220
NFP factor 14-228
packed section input 14-215
packed sections 14-201
tray spacing 14-212
Trayed Sections 14-201
trayed sections 14-201
Column Subflowsheet 2-4
relationship with main flowsheet 2-9–2-
11
Component
Flow Rate Specification (Column) 2-122
Fractions Specification (Column) 2-122
Ratio Specification (Column) 2-123
Recovery Specification (Column) 2-123
Component Curves Utility 14-23
results 14-26
Component Map 13-10
Component Splitter 10-2
splits page 10-6
theory 10-2
Compressor, Centrifugal 9-2
curves 9-17
isentropic efficiency 9-4
solution methods 9-3
theory 9-4
Compressor, Reciprocating 9-48
maximum pressure 9-53
piston displacement 9-50
rod loading 9-53
theory 9-49
Compressor/Expander
capacity 9-41
duty 9-39
efficiency 9-39
features 9-3
head 9-41
holdup 9-47
speed 9-42
surge control 9-43
Cond H
See also ESTIM DRU
iteration output
Cond Hz
See also ESTIM DRU
iteration output
Cond T
See also ESTIM DRU
iteration output
Condenser
fully-condensed 2-24
fully-refluxed 2-24
partial 2-24
See Vessels
Condenser (Column) 2-138
duty 2-142
pressure drop 2-141
subcooling 2-142
Conduction through insulation/pipe 6-84
Control Valve 5-175
See Valve 5-175
Controller
See PID Controller or Digital Point
Conv
See also ESTIM DRU
iteration output
Cooler 4-45
duty 4-50
pressure drop 4-49
theory 4-45
zones 4-53
Cooler/Heater
dynamic specifications 4-58
holdup 4-61
pressure drop 4-46
zones 4-57, 4-59
Crash tolerance
See also ESTIM DRU.c
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The I-3
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initial problem parameters
Create Column Stream Spec Button 12-12
Critical Properties Utility
analysis 14-32
quick start 14-29
true and pseudo 14-29
CSTR 8-5
reactions 8-17
Cut Point Specification 2-124
Cyclone 11-8
constraints 11-14
parameters 11-10
sizing 11-13
solids information 11-11
D
Damping Factors
recycle 5-209
Darcy friction factor 6-170
Data Recon Utility
property view
DCS Tags tab 14-46
Parameter Fit tab 14-45
Results tab 14-42
Stream Initialization tab 14-44
Data Set Configuration
See also Data Recon Utility
Configuration tab
Delta Temp Specification
column 2-125
heat exchanger 4-107
LNG exchanger 4-177
Depressuring Utility
types 14-63
Derivative level
See also ESTIM DRU
initial problem parameters
Difference interval
See also ESTIM DRU
initial problem parameters
Digital Point
connections 5-181
parameters 5-182
Direct Action 5-110
direct energy stream 1-16
Distillation Column
See Column
Distillation Column Template 2-33
Dittus and Boelter Correlation 6-82
Draw Rate Specification (Column) 2-124
Duty Ratio Specification (Column) 2-126
Duty Specification
column 2-125
heat exchanger 4-107
Dynamic Depressuring 14-60
connections 14-65
detailed heat loss 14-74
heat flux 14-69
operating conditions 14-82
operation modes 14-63
performance 14-85
pv work term contribution 14-81
simple heat loss 14-73
strip charts 14-67, 14-86
subflowsheet 14-61
valve equations 14-77
valve parameters 14-77
Dynamic Estimates Integrator 2-73
dynamics mode
license 1-4
E
Energy Stream 12-2
convert to material stream 12-3
Envelope Utility 14-87
connections 14-88
PF-PH-PS 14-91
plots 14-89, 14-144
pressure-temperature 14-90
TV-TH-TS 14-91
EPS (machine precision)
See also ESTIM DRU
initial problem parameters
Equilibrium Reactor 8-22
Ergun Equation 8-81
ESTIM DRU
diagnostic file output
final output 14-58
initial problem parameters 14-53
iteration output 14-56
error detection/correction 14-35
gross error detection 14-37
model updating 14-35
utilities 14-35
utilizing 14-35
Examples
pipe segment 6-106
Expander 9-2.c
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The I-4
I-4
curves 9-17
isentropic efficiency 9-4
solution methods 9-3
theory 9-4
F
Face Plate 5-285
Face Plates
object inspection 5-287
Feed Ratio Specification (Column) 2-126
Feeder Block 12-34
Filters
baghouse 11-3
rotary vacuum 11-22
Fired Heater (Furnace)
combustion reaction 4-64
conductive heat transfer 4-69
convective heat transfer 4-68
duty 4-83
dynamic specifications 4-70
features 4-63
flue gas 4-86
flue gas pf 4-88
heat transfer 4-65, 4-79
holdup 4-89
nozzles 4-79
process fluid 4-85
radiant heat transfer 4-67
sizing 4-75
theory 4-64
tube side pf 4-87
Fittings Database
modifying 6-106
Fletcher Reeves Method (Optimizer 
Operation) 7-16
Flow Control Valve (FCV) 5-175
Flowsheet
tags 13-6
Flowsheet Menu
notes manager 1-28
Function precision
See also ESTIM DRU
initial problem parameters
G
Gap Cut Point Specification 2-127
General Balance 5-26
ratios 5-26
Gibbs Reactor 8-28
Gregory Aziz Mandhane Correlation 6-60
H
Heat Balance 5-25
Heat Exchanger 4-89
basic model (dynamic rating) 4-102, 4-
114
delta pressure 4-118
detailed model (dynamic rating) 4-102, 4-
116
dynamic rating 4-102
dynamic specifications 4-93
end point design model 4-97, 4-101–4-
102
heat balance 4-105
heat loss 4-124
holdup 4-136
models 4-97
plots 4-128
pressure drop 4-92
See also Vessels
steady state rating model 4-101
theory 4-90
weighted design model 4-99, 4-102
Heat Exchangers
zones 4-116
Heat Loss Model
detailed 10-30
heat exchanger 4-124
simple 4-51, 10-28
Heat Transfer
coefficients 4-117
conductive elements 4-121
convective elements 4-121
duty parameters 1-16
kettle chiller 1-20
kettle heat exchanger 1-20
kettle reboiler 1-20
PFR 8-82
reactors 8-41
separator 10-15, 10-50
tank 10-15, 10-50
three-phase separator 10-15, 10-50
Heater 4-45
duty 4-50
pressure drop 4-49
theory 4-45
zones 4-53
Heavy Key (Shortcut Column) 10-53.c
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The I-5
I-5
Hydrate Calculation Models 14-126
assume free water 14-131
asymmetric 14-132
symmetric 14-132
vapour only 14-132
Hydrate Formation Utility 14-126
calculation models 14-126
formation pressure 14-138
formation temperature 14-137
hydrate inhibition 14-138
ice formation 14-133
stream conditions 14-135
Hydrocyclone 11-16
constraints 11-21
parameters 11-18
sizing 11-20
solids information 11-19
Hysteresis 6-122
HYSYS Dynamics License 1-4
I
If/Then/Else Statements 5-235
Infinite bound size
See also ESTIM DRU
initial problem parameters
Infinite step size
See also ESTIM DRU
initial problem parameters
Inform
See also ESTIM DRU
final output
Input Experts 2-27
Inside Film Convection 6-81
Isentropic Power 9-7
Iteration Count
recycle 5-206, 5-209
Itn
See also ESTIM DRU
iteration output
ItQP
See also ESTIM DRU
iteration output
J
JJ initial Hessian
See also ESTIM DRU
initial problem parameters
K
k Values
 See also specific Unit Operations
L
Lag Function
second order 5-277
Lagr Mult
See also ESTIM DRU
final output
Lapple Efficiency Method (Cyclone) 11-11
Leith/Licht Efficiency Method (Cyclone) 11-11
Light Key (Shortcut Column) 10-53
Lin
See also ESTIM DRU
iteration output
Linear constraints
See also ESTIM DRU
initial problem parameters
Linear feasibility
See also ESTIM DRU
initial problem parameters
Liner parameters 6-28
Linesearch tolerance
See also ESTIM DRU
initial problem parameters
Liquid Flow Specification (Column) 2-128
Liquid Heater 1-17
Liquid-liquid Hydrocyclone
add 6-23
attach streams 6-24
characteristic diameter 6-18
configure Liner type 6-28
configure parameters 6-25
Connections page 6-24
create 6-23
cummulative distribution 6-17
delete 6-24
dense dispersion 6-21
Design tab 6-24
dimensions schematic 6-18
Droplet Distribution page 6-29
Dynamics tab 6-34
General page 6-30
general results 6-30
Geometric page 6-31
geometric results 6-31
graphical representation 6-22.c
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The I-6
I-6
hydraulics 6-19
Hydrocyclone Number 6-19
ignore 6-24
inlet diameter 6-18
Liner Details page 6-28
Liner dimensions 6-18
Migration Probability 6-21
Migration Probability results 6-33
MP 6-21
nomenclature 6-34
Notes page 6-30
oil droplet distribution 6-17
Oil Droplet Distribution results 6-33
overflow diameter 6-18
Overflow page 6-31
overflow results 6-31
Parameters page 6-25
Performance tab 6-30
Plots page 6-33
property view 6-23
Reduced Migration Probability 6-21
Reynolds Number 6-19
RMP 6-21
Rosin Rammler distribution 6-29
Rosin Rammler modal diameter 6-17
Rossin Rammler 6-17
separation efficiency 6-22
Serck Baker OilSpin 6-28
split ratio 6-20
Tabular page 6-33
Taper angles 6-18
theory 6-16
underflow diameter 6-18
Underflow page 6-32
underflow results 6-32
User Variables page 6-30
Vortoil G-liners 6-28
Worsheet tab 6-34
LMTD
air cooler 4-4, 4-13
heat exchanger 4-91
LNG exchanger 4-178, 4-187
LNG
counter current flow 4-195
cross flow 4-195
dynamic specifications 4-196
features 4-163
heat transfer 4-182
holdup 4-198
k values 4-197
laminar flow 4-197
layers 4-180–4-181, 4-191
parallel flow 4-195
pressure drop 4-165, 4-196
zones 4-180
LNG Exchanger 4-163
heat balance 4-175
plots 4-189
Logical Operations
See Digital Point, PID Controller, Selector 
Block, Set, Spreadsheet and 
Transfer Function
Lower Bound
See also ESTIM DRU
final output
M
Main Flowsheet
relationship with column subflowsheet 2-4
Majits
See also ESTIM DRU
final output
Major iterations limit
See also ESTIM DRU
initial problem parameters
Major print level
See also ESTIM DRU
initial problem parameters
Manipulated Variables 5-197
Mapping 13-10
Mass Balance 5-24
Material Stream 12-5
Minor iterations limit
See also ESTIM DRU
initial problem parameters
Minor print level
See also ESTIM DRU
initial problem parameters
Mixed Method (Optimizer Operation) 7-15
Mixer 6-35
holdup 6-42
nozzles 6-40
Mole and Heat Balance 5-25
Mole Balance 5-24
MPC Controller
output target object 5-138.c
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The I-7
I-7
N
Net Positive Suction Head (NPSH) 9-82
Neural Networks
See Parametric Unit Operation
Neural Networks See Parametric Utility.
NFP Factor
See Column Sizing Utility.
Ngrad
See also ESTIM DRU
final output
Nonlinear constraints
See also ESTIM DRU
initial problem parameters
Nonlinear feasibility
See also ESTIM DRU
initial problem parameters
Nonlinear Jacobian vars
See also ESTIM DRU
initial problem parameters
Nonlinear objective vars
See also ESTIM DRU
initial problem parameters
Norm Gz
See also ESTIM DRU
iteration output
Normalizing Compositions 12-25
NormGf
See also ESTIM DRU
iteration output
Notes Manager 1-28
Nz
See also ESTIM DRU
iteration output
O
object inspect menu 1-11
Objective
See also ESTIM DRU
iteration output
Observarable Variables 5-198
OLGAS Correlation 6-62
Operation(s)
installing 1-6
property view 1-9
Optimality tolerance
See also ESTIM DRU
initial problem parameters
Optimization Objects 14-48
property view
Connection tab 14-49
Properties tab 14-49
Transfer tab 14-52
Optimizer 7-2
BOX method 7-14
configuration tab 7-4
constrant function 7-8
example 7-35
fletcher reeves method 7-16
function setup 7-12
hyprotech sqp 7-18
mdc optim 7-4
mixed method 7-15
optimizing overall UA 7-40
original 7-5
property view 7-3
quasi-newton method 7-16
schemes 7-12
SQP method 7-15
tips 7-17
types 7-4
Outside Conduction/Convection 6-83
P
Packed Towers
See Column Sizing Utility.
Parameter/Offsets
See also Data Recon Utility
Results tab
Parametric 14-145
Parametric Unit Operation 5-190
connections 5-191
inputs from data file 5-193
manipulated variables 5-197
observable variables 5-198
setup 5-195
training 5-198
training pairs 5-197
utility data 5-192
Parametric Utility 14-145
Paste Exported Objects 13-5
Percent Heat Applied 1-17
Petukov Correlation 6-81
PFR. See Plug Flow Reactor
Physical Property Specification (Column) 2-
128
PID Controller
ATV tuning 5-282.c
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The I-8
I-8
configuration 5-107, 5-141
connections 5-102
control valve 5-175
controller action 5-110
Faceplate 5-180
flow control valve 5-175
modes 5-108
output target object 5-105
process variable source 5-103, 5-138
set point ramping 5-112
tuning 5-109
Pipe Contribution 6-169
Pipe Material Type 6-71
Pipe Segment 6-43
adding 6-68
calculation modes 6-44
example 6-106
flow calculation 6-48
heat transfer 6-77
length calculation 6-47
material and energy balances 6-49
pressure drop calculation 6-45
removing 6-77
roughness factor 6-70
sizing 6-67
Pipe Sizing Utility 14-172
Pipe. See Pipe Segment
Plug Flow Reactor 8-74
catalyst data 8-91
duty 8-82
heat transfer 8-82
physical parameters 8-100
pressure drop 8-80
reaction balance 8-96
reaction extents 8-95
reactions 8-87
sizing 8-97
Plug Flow Reactors (PFR)
duty 8-106
k values 8-104
segment holdup 8-105
Polytropic Efficiency 9-19, 9-37, 9-62
Polytropic Power 9-7
Power Requirement
pump 9-64
Pressure Flow
pipe contribution 6-169
Pressure Profile
LNG exchanger 4-173
Product Block 12-34
Property Table Utility 14-187
dependent variables 14-190
independent variables 14-188
plots 14-193
tables 14-192
Pump 9-63
capacity 9-94
curve data 9-77
curve profiles 9-79
curves 9-69
dynamic specifications 9-91
efficiency 9-93
features 9-63
generate curve options 9-80
head 9-92
holdup 9-95
inertia 9-84
linked 9-73
nozzles 9-84
NPSH 9-82
power 9-94
pressure rise 9-93
pump efficiency 9-64
pump switch 9-66
speed 9-93
theory 9-64
Pump Around 2-85
column specifications 2-128
Q
Quasi-Newton Method (Optimizer Operation) 
7-16
R
Reactor 8-3
CSTR 8-5
equilibrium 8-22
general 8-5
gibbs 8-28
parameters 8-7
PFR 8-74
Reactors
duty parameters 8-41
heat transfer 8-41
holdup 8-40
nozzles 8-35
See also Vessels
Reboiled Absorber.c
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The I-9
I-9
See Column
Reboiled Absorber Template (Column) 2-32
Reboiler 2-25
See Vessels
Reboiler (Column) 2-157
duty 2-159
pressure drop 2-159
Reciprocating Compressor
features 9-49
Recycle 5-199
calculations 5-213
damping factors 5-209
maximum iterations 5-208
types 5-207
Reflux Ratio Specification (Column) 2-131
Refluxed Absorber
See Column
Refluxed Absorber Template (Column) 2-32
Relief Valve 6-111
capacity correction 6-116
flow equations 6-116
holdup 6-122
nozzles 6-119
types 6-115
valve lift 6-121
Reset frequency
See also ESTIM DRU
initial problem parameters
Residual
See also ESTIM DRU
final output
Resistance Equation
rotary vacuum filter 11-28
Reverse Action 5-110
Rosin Rammler distribution 6-29
Rotary Vacuum Filter 11-22
cake properties 11-27
parameters 11-25
resistance equation 11-28
sizing 11-26
Roughness Factor (Pipe) 6-70
S
Secant Method (Adjust) 5-9
Selector Block 5-219
connections 5-220
Separator 10-12
duty parameters 2-153, 2-168, 10-50
heat exchanger 10-50
kettle heat exchanger 2-153, 2-168
physical parameters 10-15
reaction sets 10-21
See Vessels
theory 10-14
Sequential Quadratic Programming 
(Optimizer Operation) 7-15
Serck Baker Oilspin liners 6-16
Set 5-226
Set Point Ramping 5-112
Shells
baffles 4-113
diameter 4-112
fouling 4-112
in parallel 4-110
in series 4-110
shell and tube bundle data 4-112
Shortcut Column 10-51
Side Operations Input Expert 2-82
Side Rectifier 2-84
Side Stripper 2-82
Sieder and Tate Correlation 6-82
Simple Filter. See Simple Solid Separator
Simple Solid Separator 11-29
splits page 11-32
Solid Operations
baghouse filter 11-3
cyclone 11-8
hydrocyclone 11-16
rotray vacuum filter 11-22
simple solid separator 11-29
Solver Parameters and Tolerances
See also Data Recon Utility
Configuration tab
Specifications
active 2-44, 4-106
advanced solving options 2-49
alternate 2-45
completely inactive 4-106
current 2-45
estimate 2-44, 4-106
fixed and ranged 2-50
heat exchanger ??–4-744-105–4-107
LNG Exchanger 4-175
primary and alternate 2-50
property view 2-48
types 2-121
Splits
component splitter 10-6.c
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The I-10
I-10
Simple Solid Separator 11-32
Spreadsheet 5-229
exporting variables 5-230, 5-236, 5-239
general math functions 5-232
importing variables 5-230, 5-236, 5-239
logarithmic functions 5-233
logical operations 5-235
trigonometric functions 5-234
SQP Method. See Sequential Quadratic 
Programming
State
See also ESTIM DRU
final output
Steady State Mode
terminology 1-4
Step
See also ESTIM DRU
iteration output
Step limit
See also ESTIM DRU
initial problem parameters
Stopping/Resetting Column Calculations 2-
195
Stream
Column Specifications 2-135
Streams
energy (See Energy Stream)
material (See Material Stream)
Strip Chart 1-30
Subflowsheet 13-3
blank flowsheets 13-5
connections 13-6
feed and product connections 13-7
installing 13-4
mapping 13-10
parameters 13-8
transfer basis 13-9
variables 13-14
Subflowsheets
parameters 13-8
Surge Control 9-43
T
Tank 10-12
duty parameters 2-153, 2-168, 10-50
kettle heat exchanger 2-153, 2-168
physical parameters 10-15
reaction sets 10-21
See Vessels
TBP Envelope 2-103
Tear Location (Recycle) 5-214
Tee 6-124
holdup 6-131
splits 6-126
Tee (Column) 2-191
Tee Split Fraction Specification (Column) 2-
132
Templates
3 sidestripper crude column 2-26
4 sidestripper crude column 2-26
absorber 2-31
column 2-28–2-37
distillation 2-33
FCCU main fractionator 2-26
liquid-liquid extractor 2-25
reading existing 13-5
reboiled absorber 2-32
refluxed absorber 2-32
vacuum reside tower 2-26
Three Phase Distillation
detection of three phases 2-15
three phase theory 2-15
Three Phase Separator
duty parameters 2-153, 2-168, 10-50
heat exchanger 10-50
kettle heat exchanger 2-153, 2-168
Three-Phase Separator 10-12
physical parameters 10-15
reaction sets 10-21
See Vessels
theory 10-14
Training 5-198
Training Pairs 5-197
Transfer Function 5-265
integrator 5-271
lag function 5-273
lead function 5-274
sine wave function 5-278
Transport Property Specifications (Column) 2-
133
Tray Section
efficiencies 2-185
heat loss 2-182
holdup 2-190
nozzles 2-182
Tray Section (Column) 2-173
connections page 2-174
parameters page 2-175.c
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The I-11
I-11
performance page 2-186
pressures page 2-178
side draws page 2-175
Tray Sizing
% Liquid Draw 14-204
Use Tray Vapour to Size 14-207
Tray Temperature Specification (Column) 2-
132
Trayed Sections
See Column Sizing Utility.
True and Pseudo Critical Properties
See Critical Properties Utility.
Tubes (Heat Exchanger)
dimensions 4-113
heat transfer length 4-113
U
UA
LNG exchanger 4-178, 4-187
Upper bound
See also ESTIM DRU
final output
User Properties Utility 14-231
User Property Specification (Column) 2-133
Utilities
available utilities 14-4
Bad Data Elimination 14-35
boiling point curves 14-7
cold properties 14-17
column sizing 14-196
component curves 14-23
critical property 14-29
Data Reconciliation 14-35
dynamic depressuring See also Dynamic 
Depressuring 14-60
envelope 14-87
hydrate formation 14-126
Parameter Estimation 14-35
parametric 14-145
pipe sizing 14-172
property table 14-187
tray sizing 14-196
user properties 14-231
vessel sizing 14-235
Utility Data 5-192
V
Value
See also ESTIM DRU
final output
Valve 6-133
actuator 6-173
friction factor 6-170
holdup 6-171
manufacturer 6-138
nozzles 6-165
pipe contribution 6-169
sizing 6-137
sizing method 6-145
types 6-142
Vapor Flow Specification (Column) 2-134
Vapour Fraction Specification (Column) 2-134
Vapour Pressure Specifications (Column) 2-
134
Varbl
See also ESTIM DRU
final output
variable navigator 1-35
Verify level
See also ESTIM DRU
initial problem parameters
Vessel
duty parameters 1-16
kettle chiller 1-20
kettle heat exchanger 1-20
kettle reboiler 1-20
Vessel Heater 1-17
Vessel Sizing Utility
quick start 14-235
Vessels
boot 10-26
features 10-13
geometry 10-23
heater type 1-16
holdup 10-49
liquid heater 1-17
nozzles 10-26
Vortoil G-liners 6-16
W
Wave Flow (Pipe Segment) 6-60
Z
zone 4-57
Zones
cooler/heater 4-53
heat exchanger 4-116.c
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The I-12
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