Aspen utilities user guide v7 2

Aspen Utilities
V7.2
User Guide

Version V7.2
July 2010
Copyright (c) 1981 – 2010 by Aspen Technology, Inc. All rights reserved.
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Contents
Introducing Aspen Utilities .....................................................................................1
What You Need To Use This Guide......................................................................1
Section Descriptions ...............................................................................2
About This Document .......................................................................................2
Related Documentation.....................................................................................2
Technical Support ............................................................................................3
1 Aspen Utilities Planner User Interface .................................................................5
Starting Aspen Utilities Planner ..........................................................................5
Aspen Utilities Planner Main Window...................................................................5
Flowsheet Window..................................................................................6
Explorer Window....................................................................................6
Message Window....................................................................................6
Optimization Menu .................................................................................6
Initializing Physical Properties ............................................................................6
Creating and Simulating an Aspen Utilities Model .................................................8
Aspen Utilities Model Library....................................................................8
Adding Data to the Blocks .......................................................................8
Running in Simulation Mode ....................................................................8
2 Data Editors .......................................................................................................11
Profiles Editor ................................................................................................ 12
Accessing the Profiles Data Editor........................................................... 14
Editing Demand Profile.......................................................................... 15
Editing Availability Profile ...................................................................... 17
Updating Profiles.................................................................................. 18
Filtering Profile Data ............................................................................. 21
Viewing Profiles.................................................................................... 22
Printing Profiles.................................................................................... 24
Saving and Transferring Profile Data....................................................... 25
Selecting a Case .................................................................................. 26
Editing a Case...................................................................................... 27
Copying a Case .................................................................................... 28
Exporting a Case.................................................................................. 29
Changing the Location of the Databases.................................................. 31
Tariff Editor ................................................................................................... 32
Accessing the Tariff Editor ..................................................................... 33
Adding Contract ................................................................................... 35
Editing a Contract ................................................................................ 36
Deleting a Contract .............................................................................. 37
Adding Tiers ........................................................................................ 38
Editing a Tier ....................................................................................... 39
Contents iii

Entering Tariff Cost Equations................................................................ 40
Deleting a Tier ..................................................................................... 46
Saving and Transferring Tariff Data ........................................................ 47
Printing Contracts and Tiers................................................................... 48
Demand Forecasting Editor.............................................................................. 48
Accessing the Demand Forecasting Editor................................................ 49
Calculating Utility Demands ................................................................... 50
Saving Utility Demands......................................................................... 51
Modifying Demand Equations................................................................. 51
Using the DFE Equation Editor ............................................................... 52
Tips for Creating Equations.................................................................... 62
Adding an Equation .............................................................................. 64
Deleting an Equation ............................................................................ 65
Displaying Equation Variables ................................................................ 66
Using the Variable Filter ........................................................................ 67
Modifying Independent Variables in Equations.......................................... 68
Calculating Utility Demands for Multiple Periods ....................................... 69
3 Optimization Configuration ................................................................................71
Enforcing Hot Standby Requirements................................................................ 71
Configuring Startup/Shutdown Constraints ........................................................ 73
Configuring Load Shedding.............................................................................. 75
Obtaining Marginal Utility Cost ......................................................................... 77
Identifying Optimization Errors ........................................................................ 80
Presolve Error Checking ........................................................................ 81
Error Tracking...................................................................................... 82
Setting up Options for Optimization.................................................................. 85
Multiple Period Run Mode ...................................................................... 85
Settings for Mixed Integer Linear Solver............................................................ 86
Cut Strategy........................................................................................ 86
Cut off Value (Max. Expected Cost) ........................................................ 87
Optimum Gap from Optimality (%)......................................................... 87
Presolve Strategy................................................................................. 87
4 Aspen Utilities On-line Implementation..............................................................89
Calculating Utility Demand Targets ................................................................... 89
Specifying Demands for On-line Optimization .................................................... 91
5 Microsoft Excel Interface....................................................................................93
Installing the Aspen Utilities Planner Add-In ...................................................... 93
Aspen Utilities Excel Menu Items ............................................................ 94
Open Aspen Utilities File........................................................................ 95
Running a Simulation from Excel ...................................................................... 95
Creating a Simulation Links worksheet.................................................... 96
Configuring Blocks and Variables for Input to Aspen Utilities Planner .......... 97
Configuring Blocks and Variables for Retrieval from Aspen Utilities Planner.. 98
Mapping Variable Values to the Excel Flowsheet ..................................... 100
Running Data Reconciliation from Excel........................................................... 101
Accessing Reconciliation Worksheet ...................................................... 102
Configuring Blocks and Variables for Reconciliation................................. 103
Running Optimization from Excel.................................................................... 104
iv Contents

Performing User Specific Tasks before Optimization................................ 105
Producing Optimization Results and Tariff Information from Aspen Utilities 106
Obtaining Results from Multi-Period Optimization ................................... 109
6 Aspen Utilities Planner Reference ....................................................................111
Model Library............................................................................................... 111
List of Models .................................................................................... 112
General Model Structure ..................................................................... 113
Standard Variable Names in Models...................................................... 114
Ports and Streams.............................................................................. 115
Specifying Capacity Limits ................................................................... 115
Feeds ............................................................................................... 116
Demands .......................................................................................... 120
Headers ............................................................................................ 124
Steam Models .................................................................................... 127
Pumps .............................................................................................. 132
Turbines............................................................................................ 137
Heat Exchangers ................................................................................ 142
Multipliers ......................................................................................... 151
Fuel Models ....................................................................................... 154
Emissions.......................................................................................... 169
Templates ......................................................................................... 177
Flowsheet Development ................................................................................ 179
Dealing with Snapshots....................................................................... 179
Variable Specification – Fixed and Free ................................................. 179
Appendix 1 – Configuring the Demand Forecasting Editor...................................181
Before you Start .......................................................................................... 183
Units of Measure .......................................................................................... 185
Configuring General Information .................................................................... 185
EquationTypes ................................................................................... 185
Operators.......................................................................................... 186
Config............................................................................................... 186
PeriodSet .......................................................................................... 186
Period............................................................................................... 186
GeneralInput ..................................................................................... 187
Configuring Production Parameters................................................................. 187
DemandForecasting Input ................................................................... 187
XinVal............................................................................................... 189
Configuring Modes........................................................................................ 190
TblModes .......................................................................................... 190
TblModeValues................................................................................... 191
PeriodModes ...................................................................................... 191
Configuring Calculations................................................................................ 192
tblEquationDefinition .......................................................................... 192
CalcVars ........................................................................................... 193
Configuring Demand Calculations ................................................................... 195
DemandCalcsEquations ....................................................................... 195
DemandCalcs..................................................................................... 195
Contents v

Index ..................................................................................................................197
vi Contents

Introducing Aspen Utilities
In this document Aspen Utilities is used as a generic term to refer to both
Aspen Utilities On-Line Optimizer (Utilities Optimizer), formerly known as
Aspen Utilities Operations, and Aspen Utilities Planner.
Aspen Utilities V7.2 is an equation-oriented tool for the simulation and
optimization of Utility Systems (Fuel, Steam and Power), specially designed to
address all the business processes related to the operation and management
of utility systems.
It can be used to address all the key issues in the purchase, supply and usage
of fuel, steam and power within environmental constraints, and provides a
single tool to optimize energy business processes and substantially improve
financial performance.
Aspen Utilities is based on Aspen Custom Modeler. The software is supplied
with a library of unit operations associated with utility systems. You can also
write your own unit operation models and add these to the library.
Aspen Utilities uses a Mixed Integer Linear Programming (MILP) solver for
optimization.
What You Need To Use This
Guide
To use this guide, you need Aspen Utilities Planner™ installed on PC or PC file
server running Windows 2000 or Windows XP. For information on how to do
this, read the Installation Guide supplied with the product, or contact your
system administrator.
Introducing Aspen Utilities 1

Section Descriptions
This guide contains the following sections:
Introduction  a brief overview of the guide and a list of related
documentation.
Section 1 Aspen Utilities Planner User Interface  an overview of the
application software and how to create an Aspen Utilities model.
Section 2 Data Editors – Detailed information on inputting data into Aspen
Utilities – utility demands, equipment availability, tariff information, and
utility demand forecasting.
Section 3 Optimization Configuration – how to achieve certain optimization
objectives such as hot standby requirements, startup/shutdown constraints,
load shedding, and others. Also how to diagnose optimization problems.
Section 4 Aspen Utilities On-line Implementation – an overview of using
Aspen Utilities Planner with Aspen Online to get data from the plant data
historian and run calculations.
Section 5 Microsoft Excel Interface  how to run Aspen Utilities and view
results from Microsoft Excel and the necessary prerequisites.
Section 6 Aspen Utilities Reference  detailed information covering the models
used in Aspen Utilities and some ideas on flowsheet development.
Appendix 1 Configuring the Demand Forecasting Editor  detailed information
about the demand forecasting application; a subset of tables within the
demand database. These need to be configured following a certain
convention.
Glossary  an explanation of terms used throughout this guide.
About This Document
This guide is suitable for Aspen Utilities Planner V7.2 users of all levels of
experience, from new user to power-user.
For details of basic workflow, refer to the associated Getting Started guide or
the Getting Started topics in the on-line help.
Related Documentation
In addition to this document and the on-line Help system supplied with Aspen
Utilities, the following documents are provided in PDF format to help users
install, learn and use Aspen Utilities.
Title Content
Aspen Engineering What’s New and Aspen Information about new features and
2 Introducing Aspen Utilities

Engineering Known Issues known issues and workarounds.
Aspen Engineering Installation Guide and
SLM Installation and Reference Guide
Full installation requirements and
procedures required to install, verify
license and run Aspen Utilities.
Aspen Utilities Getting Started Guide Tutorials designed to train first-time
users in the main functionality and
features of Aspen Utilities.
Technical Support
AspenTech customers with a valid license and software maintenance
agreement can register to access the online AspenTech Support Center at:
http://support.aspentech.com
This Web support site allows you to:
 Access current product documentation
 Search for tech tips, solutions and frequently asked questions (FAQs)
 Search for and download application examples
 Search for and download service packs and product updates
 Submit and track technical issues
 Send suggestions
 Report product defects
 Review lists of known deficiencies and defects
Registered users can also subscribe to our Technical Support e-Bulletins.
These e-Bulletins are used to alert users to important technical support
information such as:
 Technical advisories
 Product updates and releases
Customer support is also available by phone, fax, and email. The most up-to-date
contact information is available at the AspenTech Support Center at
http://support.aspentech.com.
Introducing Aspen Utilities 3

1 Aspen Utilities Planner
User Interface
Starting Aspen Utilities Planner
To start Aspen Utilities Planner:
1 Click Start, and then select All Programs.
2 Point to AspenTech | Process Modeling V7.2, | Aspen Utilities
Planner, and then click Aspen Utilities Planner to launch the
application with a new flowsheet file already loaded.
3 To open an existing simulation, click File | Open.
4 In the Open dialog box, use the Look in list box to locate the directory
where the file is stored, select the file you want to open, and click Open.
Aspen Utilities Planner Main
Window
When you start Aspen Utilities Planner, the main window appears:
1 Aspen Utilities Planner User Interface 5

Optimization Menu
All Items Pane
Contents Pane
Flowsheet Window
Message Window
Flowsheet Window
The flowsheet window is where you build the flowsheet.
Explorer Window
The Explorer Window contains the All Items pane and the Contents pane.
Message Window
The message window displays all messages from Simulation to Optimization.
Optimization Menu
These menu items are used to edit/set the input for optimization – to launch
the Profiles and Tariff Editors, to make optimization settings, and to start an
optimization run.
Initializing Physical Properties
When starting a new Aspen Utilities model you must initialize the physical
properties:
6 1 Aspen Utilities Planner User Interface

1 Click on Component Lists in the Explorer pane.
2 Double-click on Default in the Contents pane. Please Confirm This
Operation dialog box is generated. Click Yes.
3 Physical Properties Configuration dialog box appears, allowing you to
set the physical properties.
o Use Aspen property system – allows you to configure using
embedded Aspen properties.
Click Use Properties definition file. Click Browse and use the Look
In list box to locate the directory where the file AspenUtilities.appdf
is stored. This is stored in the Examples subdirectory of the Aspen
Utilities installation.
Note: The default location of AspenUtilities.appdf is: installation
driveProgram FilesAspenTechAspen Utilities Planner
V7.2Examples.
The other two options: Import Aspen Properties file and Edit using
Aspen Properties are used to change the water physical property
methods or to add components for some custom reason.
o Use custom properties – allows you to use custom physical
properties. You can build a component set.
o Don’t use properties – allows properties not to be used.
4 Click OK when you have located the file.
5 If you select AspenUtilites.appdf, a Build Component List form is
loaded. This has a single component, H2O in the left hand pane. Use the
arrows in the center of the form to move the component to the right hand
pane. Click OK.

Creating and Simulating an
Aspen Utilities Model
Aspen Utilities Model Library
All unit operation and stream models are located in the Utilities Library. This
can be accessed from the All Items pane in the Explorer window.
To select a model or stream:
1 In the tree view in the All Items pane, expand the Utilities subfolder
under the Libraries folder, you can select all utilities models and streams
from Stream Type subfolder and Utility_Models subfolder.
2 Drag the model or stream onto the flowsheet window.
3 All of the functionality of Aspen Custom Modeler is available within Aspen
Utilities Planner. You can rename blocks and streams, and resize, rotate,
and flip blocks. Click on the block and right click to allow access to all of
these functions.
Adding Data to the Blocks
Data input for the various blocks is done with forms. Double-clicking on a
block loads a Summary form which contains most of the variables you want
to access. Other forms can be accessed by choosing the block, right clicking,
then choosing Forms in the context menu.
All blocks have the following forms:
 AllVariables – contains all of the variables within the block.
 Summary – contains a selection of variables that you may want to
specify or view.
 Optimization_Limits – allows you to specify hard constraints for the
item of equipment, for example, minimum steam generation capacity or
maximum power generation, etc.
Blocks may have additional forms, for example to add efficiency curves to the
block.
Running in Simulation Mode
When the flowsheet is built, it can be run in Simulation Mode provided the
model is square (i.e., the number of equations defined in the model is equal
to the number of Free variables).

…….
A simulation can be started by clicking Simulation Run on the tool bar or
from the Run menu.

2 Data Editors
There are three basic types of information input into Aspen Utilities: utility
demands, equipment availabilities, and utility tariffs. Utility demands are the
amount of each utility (e.g., HP Steam, LP Steam, etc.) that must be supplied
by the utility system. Equipment availabilities define the availability of utility
system equipment – whether the equipment is available, its minimum and
maximum, etc. These demands and availabilities can be entered for one time
period or multiple time periods. In Aspen Utilities, demands and availabilities
are entered in the Profiles Editor; the utility tariffs are entered in the Tariff
Editor. Both editors are available within the same form. Apart from the above
two editors, Aspen Utilities also has a tool for calculating utility demands from
plant production rates and operating conditions, called Demand Forecasting.
Results from Demand Forecasting can be transferred to the demand profile in
the Profiles Form. The Demand Forecasting Editor, also known as DFE, is now
available within the same form as the Tariff and Profiles editors.
All data is stored in Microsoft Access databases by default, but other
databases – Oracle and SQL Server – are supported. Profile data is stored in
ProfileData.mdb, Tariff data is stored in TariffData.mdb, and Demand
forecasting data is stored in DemandData.mdb. Apart from these three
databases, there is a fourth database used by Aspen Utilities – Interface.mdb
– which is an internal database used by optimization to collect and hold data
from the other databases and store results from an optimization run. The
following diagram highlights the overall relationships between various data
editors and corresponding databases.
2 Data Editors 11

Profiles Editor
The Profiles Editor is used to enter data for utility demands and equipment
availability. Profile data is grouped in cases. Each case contains an equipment
availability profile, a utility demand profile, and a period set. A period set
contains any number of time periods, each with its own start and end time.
The Profiles Editor form is shown here for a case named Case1.
12 2 Data Editors

The Demand Profile for Case1 is displayed with all areas, all equipments, and
all periods:
The demand profile shown above relates to the example.auf flowsheet in the
Aspen Utilities Examples folder.
In general, the demand profile shows the demand for utilities external to the
utility system flowsheet, from the process units. The example above shows
steam demand from the process units as HP Steam Use. Demands are
usually linked to feed or demand blocks in the flowsheet. The availability
profile shows availability and constraints on equipment modeled in the Aspen
Utilities flowsheet. Data for demands and availabilities are entered in the form
of a range – Min and Max. If the value is fixed, enter the same value for the
minimum and maximum.
Before the Profiles Editor can be used it is necessary to configure the profiles
database with data from the Aspen Utilities model that has been developed.
Refer to the Updating Profiles section later in this chapter.
In general, the steps in using the editor are:
1 Open the Profiles Editor.
2 Make the changes required to the demand and availability profiles. Use
Update to add or delete profiles according to the flowsheet changes.
Note: The Update button is only available when the editor is launched
from within Aspen Utilities. It’s not available in the standalone Editor
launched from the Start menu.
3 Click Save to save the data. The running status bar shows the progress. It
displays “Profile data saved successfully” when the save is completed.
2 Data Editors 13

4 Click Commit to send the data to the optimizer. (Specifically, to the
Interface database.)
5 When prompted by a period dialog, select the periods that should have
data sent to the optimizer.
6 Click Apply.
7 Click to close the editor.
Accessing the Profiles Data Editor
You can access the Profiles Editor from the Optimization menu within Aspen
Utilities by clicking on Editors… then clicking Profile on the Aspen Utilities
Planner Data Editors menu bar.
14 2 Data Editors

The following editor appears:
Editing Demand Profile
Before editing demand profiles, you need to have the equipment names and
related port names set up in the profile database tables.
Please refer to the Updating Profiles section for details. In this section, we
assume all the database tables are set up and you are only interested in
editing the existing profiles.
2 Data Editors 15

When the editor starts, it displays the Demand profiles. You can change
between Demand and Availability profiles by selecting the appropriate radio
button as shown below:
You can type in the minimum and maximum values for the selected demand
profiles as well as its unit of measure. The fields for the demand profile are:
 Legend – this is a description of the data.
 Start Time – this is the starting time and date for the period to which the
data relates.
 End Time – this is the ending time and date for the period to which the
data relates.
You cannot alter Legend, Start Time, and End Time with the editor. The time
is setup in the demand database. However, you could change them directly in
the profile database if necessary.
 Min – the minimum value in the range.
 Max – the maximum value in the range.
 Unit – the unit of measure for data entry and display. The default unit of
measure is defined within the profiles database but for any editing session
this can be changed by double clicking on the unit and selecting a new
unit.
 Area – the field used to group the processes in the plant. Area is
particularly useful for a multiplant case, where process units are often
located in different geographical locations (north, south, etc.). Refer to the
Updating Profiles section for how to set areas.
16 2 Data Editors

Editing Availability Profile
You display and edit the equipment availability profile by selecting the View
Availability Profile radio icon. The availability profile shown below relates to
the example.auf flowsheet in the Aspen Utilities Examples directory.
The Availability profile allows you to define equipment availability (on or off)
and set equipment constraints. Usually equipment design constraints are set
within the definition of the block in Aspen Utilities. However, these constraints
can be further refined within the availability profile. For example, a boiler may
be designed to generate a maximum 200 t/h of steam and have a 25%
turndown. Therefore, within the definition of the block in Aspen Utilities the
optimization limits can be set as follows:
 MinStmFlow = 50 ton/hr.
 MaxStmFlow = 200 ton/hr.
However, if for some reason the maximum generation of steam from the
boiler is limited to 150 ton/hr, this can be set as the maximum value. When
optimization is invoked, the more constraining of the limits set in the
availability profile or the optimization limits are taken.
Note: The availability profile has more than one type of data for the same
piece of equipment - availability and range (Minimum and Maximum).
The availability profile has the following data:
 Legend – a description of the data. You cannot change this value within
the editor.
 Start Time – the starting time and date for the period to which the data
relates. You cannot change this value within the editor.
 End Time – the ending time and date for the period to which the data
relates. You cannot change this value within the editor.
 Min Value – the minimum value of the range. If the data item is related
to equipment availability then this box is disabled.
 Max Value – the maximum value of the range. If the data item is related
to equipment availability then the box has a drop down list allowing you to
select the following options:
o Not Available – the item of equipment is not available for use; for
example, it is down for maintenance. In this case the optimizer cannot
switch on the unit even if it is economic to do so.
2 Data Editors 17

o Available – the item of equipment is available for use. The optimizer
can switch it on or off depending upon the economics.
o Must be on – the item of equipment must be used even if it is not
economic to do so. If equipment must be on and it is not economic to
do so, the item of equipment is usually operated at the minimum
setting.
 Unit – the unit of measure for data entry and display. The default unit of
measure is defined within the profiles database but for any editing session
this can be changed by double clicking on the unit and selecting a new
unit.
 Area – The field used to group the processes in the plant. Area is
particularly useful for a multiplant case, where process units are often
located in different geographical locations (north, south, etc.). Refer to the
Updating Profiles section for how to set areas.
If equipment availability is set as Available, the minimum value for all settings
for that piece of equipment should be set to 0 within the availability profile.
This allows the equipment usage to go to zero (not used) during the
optimization.
Updating Profiles
Before using the Editor to edit the demand and availability profiles, the
underlying Profiles database must be set up properly. The database must
contain the equipment and port name associated with the profile, its display
unit of measure, etc. As the flowsheet is developed, new process blocks might
be added to the flowsheet while others might be deleted. It is necessary to
keep the profile database updated with the changing flowsheet. The Update
feature in the Profiles Editor facilitates this and is available when the editor is
launched from within Aspen Utilities.
Note: The Update button is not available in the standalone Editor launched
from the Start Menu.
18 2 Data Editors

When you click Update on the Editor Menu bar, you are first asked to select
the profile that you wish to update:
Select the appropriate choice and click OK. Here we select Demand profile as
an example.
2 Data Editors 19

Select Ports for Demand Profile window appears:
To add a profile, select the equipment and port in the left-most two panes
and then click Add. The newly added profile will be displayed in the Selected
Ports list in the form Equipment*Port.
To remove an existing profile, select it in the Selected Ports list and click
Remove. When you close the form the selected profile is removed from the
grid.
Note: You need to click Save on the Editor Command bar to save your
changes in the Profiles database.
The following list contains brief descriptions of fields shown in the Update
window:
 Blocks – contains all blocks in the current flowsheet.
 Ports – contains all possible profile variables associated with the selected
block.
 Selected Ports – current selected profile variables and those in the
profile database.
 Add/Remove – Add/Remove port to/from the Selected Port column.
 Configure – the Configure new ports window appears when you click
Configure after new ports are added. In this window, you can select the
display unit of measurement and categorize the selected ports into
predefined areas. After clicking OK, the newly added/removed profile on
the grid appears/disappears.
20 2 Data Editors

This window will only appear for newly added profiles and will close upon
completion of last new profile configuration.
Filtering Profile Data
For a large flowsheet, there could be many demand and availability profiles,
in multiple periods. In such cases it may be difficult to locate specific profiles.
The profile filtering feature addresses this issue.
You can filter the profile data by area, equipment, or period.
By Area
Click on the area filter displays a drop-down list with all defined areas listed.
Select an item to view data relating to a specific area or to all areas.
By Equipment
Click on the equipment filter displays a drop-down list with all items of
equipment listed. Select an item to view data relating to a single piece of
equipment or to all equipments.
By Period
Click on the period filter displays a drop-down list with all periods listed.
Select an item to view data relating to a single period or to all periods.
Note: The equipment filter and the period filter can be used together.
2 Data Editors 21

Viewing Profiles
In addition to the equipment view of profile data, you can click on View in the
main command bar in the editor and switch to period view.
Equipment View
22 2 Data Editors

Period View
2 Data Editors 23

Printing Profiles
Demand and equipment availability profiles can be viewed and printed in
HTML format. The Print preview window appears when you click Print on
the Editor Menu bar. This is the HTML view format of the selected profile.
Click Print on the Print preview window, the report will be sent to the
printer. Meanwhile, a Save As dialog box appears which allows you to save
the report.
24 2 Data Editors

Saving and Transferring Profile Data
After changing demand and equipment profiles, save the changes to the
Profiles database by clicking Save on the Command bar.
In order for optimization to use the modified profile data, you also need to
transfer the profile data to the Interface database. This is done by clicking
Commit on the Command bar. Commit also saves the profile data to the
Profiles database:
2 Data Editors 25

Selecting a Case
Each Profiles database can contain many cases, which may represent different
operating scenarios for the utility plant. When the Profiles editor is first
launched, the profile data in the default case is displayed, as shown below:
You can display, edit, and transfer profile data in other cases by selecting a
different case in the drop-down list.
26 2 Data Editors

Editing a Case
Each case contains a set of demand profiles and a set of availability profiles.
The Demand and Availability profiles that comprise a case can be changed
with the Edit Case dialog box shown below. This case editing capability,
along with other case management features, allows you to easily carry out
What-if analyses when multiple operating scenarios exist in the utility plant.
The following dialog box is displayed when you click Edit on the Editor Menu
bar:
 Demand profile – all demand profiles are listed in the drop-down list and
the current demand profile is highlighted.
 Availability profile – all availability profiles are listed in the drop-down
list and the current availability profile is highlighted.
 Select Period Set – all period sets are listed in the drop-down list and
the current period set is highlighted.
2 Data Editors 27

Copying a Case
Copy case is used to copy an entire case to a new case. This is also an easy
way to generate a new case. Clicking Copy in the Editor Menu bar displays
the following dialog box:
Case Frame
 Name – the name for the new case.
 Description – the new case description.
Profile Frame
 Copy Profile (check box) - Indicates that the current demand and
availability profiles, listed here, should be copied to the new case.
 ID - The demand and availability profile ids for the new case.
 Name - The demand and availability profile names for the new case.
 Description - The demand and availability profile descriptions in the new
case.
Period Set Frame
 Copy Period Set (check box) - Indicates that the current period set,
listed here, should be copied to the new case.
 ID - Period set ID for the new case.
 Description - Period set description for the new case.
28 2 Data Editors
Case Frame
Profile frame
Period set
frame

Exporting a Case
Export case is used to Import/Export the case from/to an external source
(database or data source file). The Select database to import/export case
window appears when you click Export on the Editor Menu bar:
Select the correct location in Look in drop down list to find the external data
source file you want to import/export.
2 Data Editors 29

After a source has been selected, the Import/Export Case window displays:
All cases in the current profile database are listed in the left column. All the
cases in the external database are listed in the right column. From here, you
can decide which case or which profile in the case to export or import.
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Changing the Location of the Databases
You can change the location of the Aspen Utilities databases by clicking
Configure on the Editor Menu bar:
Browse to each of the Profile, Tariff, Demand and Interface databases and
click OK.
The Set for all users checkbox is used to set the same database location for
all users. When this is unchecked, only Registry values in
HKEY_CURRENT_USER are set. When this is checked, Registry values in both
HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE are set.
2 Data Editors 31

Tariff Editor
Optimization in Aspen Utilities is all about cost saving on utilities, i.e.,
minimizing the total utility cost during the plant operation. The input cost data
to Aspen Utilities is the price of each purchased or sold utility. The Tariff
editor is used to enter this information. This Tariff data is stored in an Access
database (TariffData.mdb). As in Profiles data, you must transfer the data to
the optimizer before an optimization run takes place.
The tariff structure defined in Aspen Utilities contains two components, the
Contract and the Tier. In the tariff editor, you define a Contract in Contract
Definition Table for each utility purchased or sold. For each contract, you
create one or more tiers to define the actual utility price. In many cases,
utility tariffs vary non-continually with usage or usage rate. To handle these
types of contracts, multiple tiers are used to define various price structures in
a utility contract.
In general, follow below steps to use the Tariff Editor:
1 Open the Tariff editor from the Optimization menu.
2 Make the necessary changes to the contracts and tiers.
3 Click Save to save the data in the Tariffs Database.
4 Click Commit to save the data in the Tariff database and to send the data
to the optimizer.
5 Click Exit to close the editor.
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Accessing the Tariff Editor
The Tariff Editor is accessed from the Optimization menu in Aspen Utilities
Planner by clicking Editors…, then clicking Tariff on the Aspen Utilities
Planner Data Editors Menu bar.
2 Data Editors 33

The following window appears after clicking Tariff:
All contracts are listed in the upper-half of the table, and the tiers of the
selected contract are listed in the lower half of the table. You can add and
delete contracts and tiers by using Add and Delete on the Command bar.
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Adding Contract
When new purchased or sold utilities are introduced into the flowsheet, you
will need to add a new contract. To add a new contract, right click the mouse
somewhere in the top table and select Add contract. Alternatively, you can
click the arrow on Add and select Contract in the drop-down menu:
To edit an existing contract, double-click on a selected field to enter edit
mode.
To delete an existing contract, click on the relevant contract in the contract
definition table, then either right click the mouse and select Delete Contract,
or click the arrow on Delete and select Contract in the drop-down menu.
For each new contract, you need to provide a unique Contract ID. You must
also specify the Block and Port that the utility represents in the flowsheet.
Click on the drop-down list in the Block and Port fields to select blocks and
ports.
The following data is required for defining a contract:
 Contract ID – you must supply a unique name for the contract.
 Block – the name of the block (usually a feed or demand block) in Aspen
Utilities flowsheet which uses or provides the utility in the contract. The
2 Data Editors 35

previous example shows a Block name of FuelFeed, which is a unit
operation in the example file, example.auf.
 Port – a drop-down list from which you select the port in the block that
provides or uses the utility in the contract. The previous example shows a
Port name of FuelOut1, which is a port name in unit operation FuelFeed in
the example file, example.auf.
 Buy/Sell – this allows you to specify whether the utility is bought or sold.
In the previous example the utility is bought.
 Utility Type – a drop-down list from which you select one of three utility
types: Fuel, Electricity, or Steam. In the previous example the utility type
is Fuel.
 Use Forecast – allows you to specify if a forecast is to be used. This is
very important if there are (for example) annual limits associated with the
contract. If ‘Yes’ is selected, additional data is required.
 Used to Date - this input is only enabled if a Forecast is used. You must
enter the amount of utility used from the start of the contract period to
the current date.
 Forecast - this input is only enabled if a Forecast is used. You must enter
a forecast of the amount of utility used between the end of the run period
and the end of the contract period.
 Do Peak – a peak contract is defined as a contract in which the cost is
linked to the peak usage. Select Yes to define a peak contract, No
otherwise.
 Peak Price – enter here the peak cost in the contract, in units of
monetary unit/usage. Valid when Do Peak is Yes.
 Peak Value – specify the peak usage value. For Usage type contracts
(Rate/Usage field), this is the maximum amount of the utility used so far.
 Disabled – a contract can be temporarily disabled so that it will not be
used in the optimization.
 Rate/Usage – you can select how the contract is controlled, on an hourly
basis or on a total usage basis. If the contract is controlled on a total
usage basis, then it is advisable to use a forecast.
 Unit – you can select the unit of measure for data entry and display.
Editing a Contract
Edit mode is entered when you double-click in any grid cell.
36 2 Data Editors

Deleting a Contract
To delete a contract, select a contract in the contract definition table and click
Delete | Contract on the Command bar:
Alternatively, select a contract in the Contract Definition table, right click the
mouse in any cell, and select Delete Contract.
2 Data Editors 37

Adding Tiers
You can add, edit, or delete tiers associated with a particular contract the
same way as for contracts. To see the tiers associated with a particular
contract, click on a Contract ID in the top Contract Definition table.
To add a tier for a contract, click Add on the Editor Menu bar, and then select
Tier from the drop-down menu (or right-click the mouse and click Add tier) a
new row is generated in the Tier Definition table. Alternatively, select a
contract, right click the mouse in any cell of the tier in the Tier Definition
table, and select Add Tier.
The following data is required to complete a tier definition:
 Tier ID – a unique identifier supplied by you.
 Variable Cost – the cost of utility per unit of use. The base unit is the
same unit of measure defined for the related contract. In this case we
would need to add the cost per GJ of fuel.
 Fixed Cost – the fixed cost portion of the contract, if any. Enter 0 if there
is no fixed cost (you cannot leave this field blank).
 Min Rate – the minimum amount of the utility that can be used in an
hour. This field is used only if the contract is controlled by Rate. If the
contract is controlled by usage, enter 0 (you cannot leave this field blank).
If the field is disabled, any entry here is not being used in optimization.
 Max Rate – the maximum amount of the utility that can be used in an
hour. This field is used only if the contract is controlled by Rate. If the
38 2 Data Editors

contract is controlled by usage, enter 0 (you cannot leave this field blank).
If the field is disabled, any entry here is not being used in optimization.
 Min Usage – the minimum amount that can be used within this tier. This
field is active if the contract is controlled by Usage. If the contract is
controlled by rate, enter 0 (you cannot leave this field blank). If the field
is disabled, any entry here is not being used in optimization.
 Max Usage – the maximum amount that can be used within this tier. This
field is used only if the contract is controlled by Usage. If the contract is
controlled by rate, enter 0 (you cannot leave this field blank). If the field
is disabled, any entry here is not being used in optimization.
 Priority – the priority order of the tiers considered in optimization. We
recommended you use integer numbers starting from 1. The lower the
number the higher the priority. For example, the optimizer is set to
maximize the use of a tier with priority 1 before using a tier with priority
2. When two tiers have same priorities the optimizer is allowed to use any
of the two or both.
 Time dependent – if the variable cost of a tier varies with time, select
Yes, if not select No. When Yes is selected, Variable Cost by Period table
appears below the Tier Definition table. Enter the variable cost for each
period.
Editing a Tier
Edit mode is entered when you double-click in any grid cell.
2 Data Editors 39

Entering Tariff Cost Equations
In many cases, the cost for a particular utility can be broken down to several
contributing cost components. For example, electricity cost typically consists
of a fixed standing charge, taxes, a unit price, delivery cost, etc. The fixed
and variable cost for each tier can be calculated by combining these individual
cost components.
In order to do this, you need to input the individual cost components and the
equations that use the cost components, for each tier.
Adding Utility Cost Components
1 Click Costing on the main command bar in the combined editor and the
cost component form is displayed:
2 Enter the name, description, and value for each cost component in the
grid.
Note: The names of the cost components cannot be duplicated. In
addition, the names cannot contain square brackets ([ and ]).
Editing Utility Cost Components
Edit or change data by typing in the cell.
40 2 Data Editors

Deleting Utility Cost Component
Delete a component by selecting the record and pressing the Delete key. A
confirmation dialog is displayed to verify the change.
Note: Deleting a cost component that is referenced in an equation will cause
errors during the equation evaluation. Therefore be careful when deleting cost
components and be sure to remove any references in the Cost Equations.
Saving Utility Cost Components
Click OK to save changes and close the form. Click Cancel to discard changes
and close the form.
2 Data Editors 41

Accessing the Tier Cost Equation Form
Cost equations can be entered for each tier when the individual cost
components have been added. Cost equations can be entered for the fixed
cost, the variable cost, or both.
The cost equation input form can be displayed in two ways:
 Click Equation on the main command bar.
 Right click the mouse in the fixed or variable cost cell in the tier table and
select Cost Equations… from the context menu.
42 2 Data Editors

Adding a Tier Cost Equation
There is a slight difference depending on how the Cost Equation form is
launched. When Equation is clicked the entire table is displayed with no
specific record highlighted. When the Cost Equations… menu item is
selected from a tier cell, the record for this tier is highlighted in the table. If
no cost equation exists, one is automatically added, as shown below.
In this screenshot, the Cost Equation form is launched from Contract Natural
Gas, tier Tier1 and the Variable Cost cell. A new record is added automatically
and you only need to enter the Equation and the optional Notes.
When the equation form is launched by clicking Equation, you need to
manually enter the Contract, Tier, and Type by selecting from the drop-down
lists.
Entering a Tier Cost Equation
When a record is selected in the Cost Equation table, the equation string is
displayed in the Cost Equation = textbox beneath the table. Edit the
equation in the textbox. To display a list of cost components, type an open
square bracket ([) and a dropdown list is displayed containing all cost
component names defined in Tariff cost components form. Scroll to the
desired cost component and select it by pressing the Space bar or by double-clicking
on it in the list.
2 Data Editors 43

Note: The equation cannot be more than 65535 characters. If this becomes a
limitation, Aspen Utilities recommend using shorter cost component names to
reduce the length of the equation string. You can provide a meaningful
description for the cost component in the Notes field; this description is
shown when the cost component is selected.
You can use any functions or mathematical operators that are recognized by
Microsoft Excel since Excel is used to evaluate the equation. When you click
on the Value cell the equation is evaluated and the result will be displayed.
The following screenshots illustrate how to select cost components, their
descriptions, and building an equation:
Typing a left square bracket [ displays a list of all defined cost components.
The text entered in the Notes field is displayed in the tool-tip window.
44 2 Data Editors

Pressing the Space bar or double-clicking on the name in the list substitutes
the name into the equation and closes the bracket.
Editing a Tier Cost Equation
Edit or change equation by typing in the text box.
2 Data Editors 45

Deleting a Tier Cost Equation
Delete a cost equation by selecting the record and pressing the Delete key. A
confirmation dialog is displayed to verify the change.
Saving a Tier Cost Equation
After editing the cost equation in the text box, you can close the Tariff Cost
Equations dialog box directly and the new edited cost equation will be saved
automatically. This also means there is no cancel that discards changes.
Deleting a Tier
To delete an existing tier, select the desired contract in the top table, then
select the desired tier in the Tier Definition table, and click Delete | Tier
from the Command bar. Alternatively, select the tier, right click the mouse in
any cell, and select Delete Tier from the context menu.
46 2 Data Editors

Saving and Transferring Tariff Data
After you add, edit, or delete contracts and tiers, you can save the changes in
the Tariff database by clicking Save on the Command bar.
In order for optimization to use the modified tariff data, you need to transfer
the tariff data to the Interface database. This is done by clicking Commit on
the Command bar. Commit also saves the tariff data to the Tariff database:
2 Data Editors 47

Printing Contracts and Tiers
Like the Profiles editor, the Tariff editor also allows you to view and print the
contracts and tiers in HTML format. The following window is displayed by
clicking Print on the Menu bar:
When you select and click OK, the corresponding report print preview is
displayed. Click Print on the Print preview window, the report will be sent
to the printer and at the same time a Save As dialog box will be loaded which
allows you to save the report.
Demand Forecasting Editor
The Demand Forecasting Editor is used in conjunction with two Access
databases to calculate utility demands from plant production rates. The
equations relating utility demand to production rate are stored in an Access
database, DemandData.mdb. The calculated utility demands are stored in a
second access database, ProfileData.mdb.
The DemandData.mdb file for a specific application must be pre-configured
before the Demand Forecasting Editor can access it. Refer to Appendix 1 –
Configuring the Demand Forecasting Editor for information how to do this.
The discussion here assumes the Demand database has been configured.
In general, follow below steps when using the Demand Forecasting Editor.
1 Click Optimization | Editors… from the Aspen Utilities menu to open the
Demand Forecasting Editor or launch the standalone editor from the Start
menu. Click on DFE in the command bar.
2 Make the changes required to the demand and availability profiles.
3 Click Calc in the Command bar to calculate the utility demands. The
running status bar shows the progress.
4 Click Save to save the data. This saves the utility demands to the Profiles
database (ProfileData.mdb) and updates the production parameter
information in the Demand database (DemandData.mdb).
5 Click to close the editor.
6 At any time you can click on (in the lower right-hand corner) to view a
log file detailing the status of the Demand Forecasting Data and
Calculations.
48 2 Data Editors

Accessing the Demand Forecasting Editor
The Demand Forecasting Editor can be accessed by clicking DFE in the Aspen
Utilities Editor, launched from Start | All Programs | AspenTech | Process
Modeling V7.2 | Aspen Utilities Planner | Editors.
The following editor appears:
2 Data Editors 49

Calculating Utility Demands
1 Enter the following data to calculating utility demands:
o Number of Periods – the number of periods to calculate.
o Start time – the starting time for the first period.
o Start date – the starting date for the first period.
o Period Length – the length of each period in hours.
o Modes – select the mode of operation for the period for each process
unit that has multiple modes of operation, using the drop-down list.
o Inputs – the value of each production parameter for each period
(e.g., production flow rate).
2 Click Calc to calculate the utility demands. The calculated utility demands
can be seen in the lower pane of the window:
50 2 Data Editors

Saving Utility Demands
Click Save to save the calculated utility demands to the Profiles database
(ProfileData.mdb) and to update the production parameter information to the
Demand database (DemandData.mdb).
Modifying Demand Equations
Go to the bottom pane and use the scroll bars to search for the utility demand
you want to change. Click Edit next to the Unit column to see the equation
editor. The equation editor for the utility HP Steam Use is shown here:
2 Data Editors 51

Demand Forecasting Equation Editor Layout
The Equation Editor contains two fields:
 Equation Editor
 Equations Viewer
Equation Editor
The Equation Editor field is for you to edit demand forecasting equations. The
table at the top contains all of the equations that have been defined. When
you click on an equation in the grid, the equation definition is displayed in the
below text box.
The equations with the Demand check box selected at the top table means
they are the equations for utility demand.
In the example above the HP Steam Use equation contains two variables:
[cvY1] and [cvY2]. Variables are contained with square brackets [ ].
Variables can be defined as values (e.g., 5, Mode1, True), or other
equations. Variables that represent equations are displayed in the table at the
top and all other variables are displayed by clicking Variables….
Equations Viewer
You can view the equations defined in this field and evaluate them. Select the
variable you want to see from drop-down list and the equation it represents is
displayed in the text box at the bottom. In this field, you can only check the
equations but cannot edit. In the example above, [cvY1] is selected in the
drop-down list and the equation it represents seen at the bottom. You can
evaluate the equation by clicking Evaluate next to the equation.
Using the DFE Equation Editor
An example will show how to use the DFE Equation Editor. The example will
create the HP Steam Use equation, starting with nothing.
The HP Steam use is given by:
 If the season is winter:
HP Steam Use = 6 + 0.2*X1 + 2*X1^2
Where X1 is the propylene production rate. And if X1 is less than or equal
to zero, it returns 0.
If season is not winter, HP Steam Use = 90 tonnes/hr
 If the Acetic acid mode is Lean:
HP Steam Use = 0
1 Click on Edit next to the unit of measure for HP Steam Use.
The Equation Editor window appears:
52 2 Data Editors

Notice that there is no equation defined for HP Steam Use. The first step is
to create the equation.
2 Click Add Equation… and fill information requested in Add Equation
dialog box:
If you need to set this equation as a utility demand, then select the Set
this equation to be a utility demand check box.
3 Click OK and you return to the Equation editor ready to create the
equation for cvY1:
2 Data Editors 53

The basic equation is given by: 6 + 0.2*X1 + 2*X1^2 where X1 is the
propylene production rate. Because we want this to be evaluated only
when the season is winter we can put an IF statement around the
equation:
IF("[SEASON]"="(SEASON.Winter)",6+0.2*[X1]+2*[X1]^2,0)
Note: In this example, SEASON is case sensitive, The value in the
equation should use the same case as what is displayed in the Variables
table (click Variables… to open). If you use SEASON.WINTER in the
equation, the equation will not work properly.
Also, we want to return 0 if X1 is less than or equal to zero. We can create
a nested IF statement to do this:
IF("[SEASON]"="(SEASON.Winter)",IF([X1]>0,6+0.2*[X1]+2*[X1]^2,
0))
And if season is not winter, the value of HP Steam Use is 90 tonnes/hr. So
the final equation should be:
IF(“[SEASON]”=”(SEASON.Winter)”,IF([X1]>0,6=0.2*[X1]+2*[X1]^2,
0),90)
Begin by typing to the first left square bracket [. When you type the left
bracket, a list is displayed with all of the variables known to DFE:
54 2 Data Editors

4 Scroll down to SEASON and double-click.
The Equation description is shown as a small tool-tip window when a
variable is clicked:
2 Data Editors 55

Notes:
1. Notice that the right bracket is automatically inserted for you.
2. Notice that the [SEASON] is enclosed in double-quotes “” because it
contains text.
5 Continue editing:
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Note: The parentheses ( ) around the value of the text variable:
(SEASON.Winter)
When values are substituted for variables, DFE places parentheses around
the variable contents. For text values the brackets signifying variable
names are inside the double quotes, resulting in the parentheses being
inside the double quotes after substitution. Therefore, you must add
parentheses around all text values being compared.
6 Click Variables… to see the variables defined for DFE. Refer to the
section Displaying Equation Variables for more information.
Finally, complete the equation:
2 Data Editors 57

Here, X1 is the propylene production rate. The variable values substituted
into the equation are those seen by clicking Variables…. Refer to
Displaying Equation Variables for more information.
7 Click Evaluate to evaluate the equation:
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If there is an error, a red exclamation point is displayed. Holding the
mouse pointer over the exclamation point shows the error in a tool-tip
window.
2 Data Editors 59

Note: Not all errors are caught this way. Some equation errors are not
caught until Microsoft Excel is evaluating the equation. In these cases you
will see a large negative number being displayed.
8 You can edit other equations for HP Steam Use in a similar fashion.
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9 Finally, the HP Steam Use is created in the middle text box.
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Note: Newly created equation variables like cvY1 will be displayed
automatically in the drop-down variable list after entering left square
bracket [.
10 Finally, click Evaluate for HP Steam Use to check the equation entered.
11 Click OK to save your data and close the Equation Editor
Tips for Creating Equations
Here are some tips for creating equations:
 Variable substitution and equation evaluation is faster if you enter the
coefficient values directly in the equation, rather than using variables. For
example:
3.1 + 10.22*[X2]
will evaluate faster than
Var_A + Var_B*[X2]
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This will be more noticeable as the number of equations and variables get
larger.
 The maximum length of an equation string is 65535 characters, including
all spaces, brackets, and variable names. If you have a longer equation,
create multiple equation variables, an equation can be made up entirely of
equation variables and that equation can be referenced by a single
variable in another equation. That way, extremely long equation strings
can be created; there is no limit.
2 Data Editors 63

Adding an Equation
To add an equation, first create the equation variable by clicking Add
Equation… and the Add Equation dialog box appears:
Enter the Equation ID and Equation description. The Equation ID becomes the
equation variable name seen in the equation drop-down list in the Equations
Viewer field and drop-down variable list.
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Click OK to return to the equation editor. The new equation is selected and
can be entered in the text box in Equation Editor field:
Note: When adding an arbitrary equation, you must to uncheck the Set this
equation to be a utility demand checkbox. When checked, the system
assumes you are creating an equation that is linked to a utility.
Deleting an Equation
Delete an equation by selecting an equation and clicking Delete Equation….
You will be asked to confirm the deletion.
2 Data Editors 65

Displaying Equation Variables
You can view the variables that have been defined by clicking Variables…:
This table contains variables that come from the Demand and Profiles
databases as well as user-defined variables. User-defined variables include
production rate variable, mode variable and user variable.
To create a user defined variable, click Add…. The Add Variable dialog box
appears:
Notes:
66 2 Data Editors

 Variable names may not contain square brackets [ and ] since these are
used by DFE to enclose variable names.
 Variable values can be changed for any variable but only values for user
variables are saved when you click OK. This allows you to temporarily
change production rates, modes, etc., while evaluating an equation.
 Once created, a variable name and description cannot be edited. You must
delete the variable and recreate it.
Demand Forecasting Variable Location
The DFE variables are located in the following tables in the Demand database,
DemandData.mdb:
Variable Type Demand Database Table
Production rates DemandForecastingInput
Mode variables tblModes
Equation variables tblEquationDefinition
User variables tblUserVariables
Using the Variable Filter
You can shorten the list of variables displayed in the drop-down variable list
by clicking Variable Filter…:
2 Data Editors 67

Check the variables that you want to display in the drop-down variable list
when a left bracket [ is typed in the equation editor.
Modifying Independent Variables in
Equations
With the exception of user variables, the values of independent variables can
only be changed within the Microsoft Access database editor. The default
Demand database, DemandData.mdb, is located in Installation
Drive:Documents and SettingsAll UsersApplication
DataAspenTechAspen Utilities Planner V7.2Example Databases.
Refer to the Changing the location of the databases section earlier in this
chapter for how to change the location.
Click Variables… to display all variables. Find the variable description of
interest and get the Variable name.
Open the appropriate table in the Demand database (refer to Demand
Forecasting Variable Location section), find the variable name, and change its
value.
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Calculating Utility Demands for Multiple
Periods
If you set the number of periods to be higher than 1, the Demand Forecasting
editor shows an additional column of data for each additional period. The
example below shows a 5-period forecast:
The editor displays the additional columns using default values as inputs for
period length, mode values, and production rates. You can edit these inputs
either manually or by copying and pasting data from Microsoft Excel.
2 Data Editors 69

3 Optimization Configuration
This chapter describes how to set your input data to achieve specific types of
optimizations. Topics covered are: enforcing hot standby requirements,
configuring startup/shutdown constraints, configuring load shedding, and
obtaining marginal utility costs.
This chapter also describes how to identify optimization errors and gives tips
on how to fix them. Advanced optimizer settings are also discussed here.
Enforcing Hot Standby
Requirements
To enforce hot standby requirements, it is necessary to indicate which of the
steam generators are to be included within the calculation of hot standby
capacity. This setting is accessed from the Optimization_Settings form for the
block. Right click on the boiler block, for example, and select Forms |
Optimization_Settings from the context menu:
3 Optimization Configuration 71

If the block is to be included in the calculation of hot standby capacity, set
DoSteamReserve to True. The default setting is False.
To enable the hot standby calculations within the optimization:
1 Select Edit Optimization Settings from the Optimization menu in
Aspen Utilities Planner.
2 Check the Enable hot standby calculations check box.
3 The hot standby requirement is also set in this dialog box. This value must
be specified in tonnes/hr.
72 3 Optimization Configuration

4 Run the optimization as usual either from the Microsoft Excel Interface or
from Aspen Utilities Planner.
5 If the hot standby constraint cannot be met, the optimization will still
complete but with a lower hot standby capacity.
Configuring Startup/Shutdown
Constraints
It is possible to set start-up and shut-down times and costs within Aspen
Utilities. When carrying out a multi-period optimization, these values are
taken into account to determine the economic profile for utility generation
and/or purchase over the entire optimization timeframe.
Start-up and shut-down times and costs can be provided for most blocks by
accessing the Optimization_Settings form.
To enable startup and shutdown calculations, set the DoStartStop variable to
True. The default for all blocks is False.
You must then specify:
 StartUpTime – the time taken to start the unit from cold to actually
producing utility.
 StartUpCost – the hourly cost of starting up the unit.
 ShutDownTime – the time taken to shut the unit down. It is assumed
that utility is not generated from the start of the shutdown period to the
end of it.
 ShutdownCost – the hourly cost of shutting down the unit.

To enable the startup/shutdown calculations within the optimization:
1 Select Edit Optimization Settings from the Optimization menu in Aspen
Utilities Planner.
2 Check the Enable start/stop calculations check box.
3 Run the optimization as usual. If an item of equipment is set as available
within the optimization input, the cost for changing the state of that item
of equipment (starting it up if it is currently off or shutting it down if is
currently on) is calculated.

Configuring Load Shedding
Aspen Utilities Planner can be used to determine the optimum load shedding
scheme. In order to configure Aspen Utilities Planner for load shedding
optimization, you need to specify which blocks are to be included in the
optimization and their load shedding cost. Follow the steps below to configure
the Aspen Utilities model for load shedding:
1 Specify which blocks should be included in the loadshedding calculation.
This is done by setting the AllowLoadShedding parameter to True in
the AllVariables table. Right click on the block and select Forms |
AllVariables.
Repeat this step until all blocks have been specified.
2 To account for lost production and other related costs, you can enter the
cost of load shedding in LoadShedCost, further down in the AllVariables
table.
3 You must also provide the availability and demand profiles to be used in
the load shedding calculation. Do this by filling in the OptInputMods table
in the Interface database (Interface.mdb).
An example is shown below. The example also shows multiple profiles –
two time periods to be considered in the optimization.

4 As a last step of configuration, you create a loadshedding problem by
creating and invoking a script in Aspen Utilities Planner.
Do the following to create a new script:
a Click Add Script at the Flowsheet Level in the Aspen Utilities Planner
Explorer and Enter a name, e.g. SteamLoadShedding.
b Click OK and a text editor is displayed. Enter the text shown in the
screen below. Here, n should be replaced with the number of periods that
are being considered in the load shedding calculation.

c You can run the script by double-clicking on it in the Contents Pane.
You can also run the script programmatically. For example, you can create
a Visual Basic script function in Excel with the following contents:
Public Sub cmdCreateShed_Click()
On Error GoTo ErrHandle
Set AUapp = Application.Run("GetAMApp")
…
…
AUapp.Simulation.Flowsheet.Invoke "SteamLoadShedding"
Exit Sub
ErrHandle:
MsgBox Err.Description
End Sub
5 Run optimization. When the optimization is complete you can check the
solution as usual in Aspen Utilities Planner or create a Visual Basic
function to extract the results from Aspen Utilities Planner to Excel in a
user-preferred format.
Obtaining Marginal Utility Cost
To obtain the marginal cost of utility headers (e.g. steam header, fuel header,
etc.) at the optimal solution you should follow below steps:
1 Display the Optimization Setting dialog by selecting Optimization | Edit
Optimization Settings… from the Aspen Utilities Planner menu.
2 Select the check box Calculate marginal utility costs.

You must indicate which headers are to be included in the marginal cost
calculation.
3 Display the summary table for the desired header by double-clicking on it.
Select True for the IncludeMarginalCost parameter. Repeat this step
until all desired headers are specified:

4 Run the optimization. When the optimization completes the marginal cost
of header is reported in the variable MarginalCost in the summary table of
the header model.

Identifying Optimization Errors
The Aspen Utilities optimization model is linear and uses a mature integer
linear programming technique do the optimization. In the majority of the
cases the model will run without problems. However, data input errors can
cause optimization failure – namely infeasibilities.
Aspen Utilities Planner contains two error diagnostic mechanisms to help
detect optimization errors: presolve checking and error tracking. You can
access optimization error diagnostics from the Optimization menu in Aspen
Utilities Planner:
Click Optimization Error Diagnostics… to display the following window:
 Run Presolve Error Check – executes presolve error checking.
 Execute Error Tracking Run – performs error tracking.

 View LP Model – brings up a list file, (a Dash compilation file for the
model).
 View Log file – the optimization iteration log, which could contain
infeasibility information if the optimization failure is caused by infeasibility.
This file is displayed at the end of running Presolve Error Check.
Presolve Error Checking
Presolve error checking uses the built-in solver presolve checking function to
identify possible infeasibility errors (for example, a minimum bound is greater
than a maximum bound on a variable).
Below is an example of a typical user input error and presolve checking
report:
This error report indicates that the particular LP problem is infeasible due to
the equation FPort(1, Boiler, BFW), which points to port BFW in block Boiler in
the flowsheet. The infeasibility is that in this case, the lower bound of the
BFW port in the boiler is 75.8 tonnes/hr but the upper bound of connected
stream flow is 30 tonners/hr only. So the Lower Bound is greater than the
Upper Bound.
Therefore, you can correct the incorrect data and then begin your calculation.

Error Tracking
Apart from the above obvious type of infeasibility, there could be other
infeasibility due to the failure of closing the mass balance on a process block.
This is more difficult to detect and usually cannot be picked up by the solver
built-in presolve mechanism.
In Aspen Utilities Planner, error tracking is carried out by introducing a
balance variable on each mass balance equation which is minimized in the
objective function. When the optimization completes, the problematic
balance equations and corresponding blocks containing the balance equations
will be listed in the simulation message window. This should give an indication
of where to search for faulty limit specifications.
In general, this type of error is much more difficult to detect than the first
type. It requires careful engineering analysis and familiarity with the
flowsheet even after identifying the error by using Error tracking.
The following forms show an example of input error and using the error-tracking
mechanism to detect it:

Note: LP Process Steam Generation is 1000 tonnes/hr (much higher than the
maximum boiler steam generation (200 tonnes/hr)).
Although the input is correct in mathematical terms (minimum<=maximum)
and the presolve mechanism does not detect any error, it causes an infeasible
solution when the optimization runs.
An Error Tracking run with the input data has the following output:

Note: The solution contains objective function values that are very big
numbers. This usually indicates the balance variables are non-zero in some
process balance equations.
In the simulation message window, the error messages indicate that the
balance equation in block HPHDR is not balanced (this becomes balanced only
with non-zero relaxation variables). By inspecting the profiles data, we find
that the LP Steam Generation (LPGEN) is too large and hence causes the
infeasible solution.

Setting up Options for
Optimization
Multiple Period Run Mode
When running a multi-period optimization in Aspen Utilities Planner, you can
use one of two modes: Simultaneous or MultiRun. The
MultiPeriodRunMode parameter in the Globals Table is set to the desired
mode:
Simultaneous mode means that the entire optimization model covering all
periods is solved simultaneously. This approach can be slow and poses
numerical difficulties when dealing with a large optimization model. However,
under some circumstances (e.g., equipment Startup/Shutdown, when time-dependent
utility contracts need to be taken into account, etc.), this mode
must be used to satisfy optimization constraints.
MultiRun, as indicated by its name, makes optimization runs as many times
as there are periods defined in the model. Convergence is relatively fast and
robust with this mode. You should use this mode when there is no
requirement to connect one period optimization to another period
optimization.

Settings for Mixed Integer
Linear Solver
Please refer to the following Optimization Settings dialog box for settings
discussed in this section:
Cut Strategy
Cut strategy is a setting that controls the number of cuts generated in each
branch and bound solution. The following table summarizes the available cut
strategy. You should refer to general Branch and Bound methods for mixer
integer linear programming to understand more about Cuts:

Values for Cut Strategy Description
-1 Automatic selection of the cut strategy.
0 No cuts.
1 Conservative cut strategy.
2 Moderate cut strategy.
3 Aggressive cut strategy.
Cut off Value (Max. Expected Cost)
If you know you are interested only in values of the objective function which
are better than some value, you can specify this value in Cut off value
(Max. expected cost). This allows the Optimizer to ignore solving any nodes
which may yield worse objective values, saving solution time. It is set
automatically after an LP Optimizer command, unless it was previously input
here.
Note: Since cost minimization is the objective in an Aspen Utilities
optimization, the cut off value can also described as the maximum expected
utility cost.
Optimum Gap from Optimality (%)
This determines whether or not the global search will terminate. Essentially,
the global search will stop if:
| MIPOBJVAL - BESTBOUND | <= GAP (%) * BESTBOUND
where MIPOBJVAL is the value of the best solution's objective function and
BESTBOUND is the current best solution bound.
For example, if you enter a 5 (%) here, the global search will stop when a
MIP solution has been found and the Optimizer can guarantee it is within 5%
of the optimal solution.
Presolve Strategy
The Optimizer provides a number of algorithms for simplifying a problem prior
to the optimization process. This elaborate collection of procedures, known as
presolve, can often greatly improve the Optimizer's performance by
modifying the problem matrix, making it easier to solve. The presolve
algorithms identify and remove redundant rows and columns, reducing the
size of the matrix. In most cases this is a helpful tool in reducing solution
times. However, presolve is included as an option and can be disabled by
entering 0 for Presolve Strategy. Here, we have other three options: 1, 2 and
3. 1 means conservative, 2 moderate and 3 aggressive. The default value is 2
(moderate).

4 Aspen Utilities On-line
Implementation
Linking with InfoPlus.21 via Aspen Online, Aspen Utilities can be configured as
an on-line implementation. In online mode, Aspen Utilities takes data
automatically from the real-time data historian at certain time intervals and
updates the demand profiles automatically.
One of the main differences between offline implementation and online
implementation is that Aspen Utilities must run unattended. Therefore Aspen
Utilities must be configured to run without user intervention.
Calculating Utility Demand
Targets
The Demand Forecasting Editor (DFE) is normally used interactively to
calculate the utility demands. Since this is not possible in online mode you
must configure it to run in an automatic manner as described in the steps
below:
1 Setup the demand forecasting database, DemandData.mdb.
Refer to Appendix 1 – Configuring the Demand Forecasting Editor for the
detailed information on how to configure the demand forecasting
database.
2 Open the On_Line form. This form is available for all demand blocks and
for the GeneralModel block.
Right click the mouse on one of these block types and select Forms |
On_Line.
4 Aspen Utilities On-line Implementation 89

In this form you need to give the number of inputs (nInputs), its
corresponding ID and input values (array OptInputVar), the number of
process operating modes (nModes), its corresponding ID (array ModeID)
and mode value (array ModeValue). The On_line form is illustrated in the
following example.
In this example, two blocks, FCC and CRU, contribute to the total LP
consumption (LPUSE). The LP consumption correlation for FCC has one
independent variable (FCC_Throughtput) and the correlation for CRU has
two independent variables (CRU_Throughput and CRU_ARO); therefore,
the total number of inputs (nInputs) is 3. Each process has a different
operating mode and thus nModes is 2. The values for ModeID are given as
FCC_Mode and CRU_Mode, respectively (arbitrary, but descriptive). There
are two operating modes for each process and thus nModeValue is 2
respectively. You also need to specify the number of target variables, in
this case the number of LP consumption for nTargets and name of the
contribution from each process (FCC_LPUSE and CRU_LPUSE) for
TargetVariableID.
The calculation result will be displayed and stored in array TargetValue for
each processes.
90 4 Aspen Utilities On-line Implementation

Note: All these names (IDs) must be the same as those defined in the
database.
Specifying Demands for On-line
Optimization
Utility import and export can be varied in an Aspen Utilities on-line
optimization. For instance, natural gas import from the supplier could be
minimized while power export could be maximized.
This might not be the case for other utility supplies and demands. For
example, steam export from production processes cannot be changed due to
fixed production throughput or operating conditions, and steam demand from
production is also fixed due to fixed process throughput.
To handle these situations properly, you must specify which utility
feeds/demand blocks have fixed utility flow at its current value in the
optimization. Specify fixed utility flow by setting the OptInputFlag
4 Aspen Utilities On-line Implementation 91

parameter to True in the On_Line form for the various types of Feed and
Demand blocks and the GeneralModel block.
92 4 Aspen Utilities On-line Implementation

5 Microsoft Excel Interface
You can run Aspen Utilities Planner and view the results from within Microsoft
Excel. This allows you to develop a graphical representation of your flowsheet
and to retrieve and report Aspen Utilities Planner results within Excel. This
chapter describes how to use the Aspen Utilities Planner – Microsoft Excel
interface.
Installing the Aspen Utilities
Planner Add-In
The first step is to install the Aspen Utilities Planner Excel Add-In. Execute the
following steps to install the Add-In:
1 Start Microsoft Excel.
2 Select Tools | Add-ins.
3 Use Browse to find the Aspen Utilities Planner Add-In, named
utilities240.xla. This file is located in the bin subdirectory of the Aspen
Utilities installation (default location is installation drive:Program
FilesAspenTechAspen Utilities Planner V7.2bin).
4 Select utilities240.xla and click OK.
If you previously had installed this Add-In you are asked if you want to
replace the existing reference, click Yes.
5 When the Add-In installed a new menu item - named Aspen Utilities – is
added to the Excel menu bar.
5 Microsoft Excel Interface 93

Aspen Utilities Excel Menu Items
When the Aspen Utilities Planner Add-In is installed, the Aspen Utilities menu
item will be present on the main excel menu bar.
 Open Aspen Utilities File – used to browse to and select an Aspen
Utilities Planner file (an .auf file).
 Show Aspen Utilities – make Aspen Utilities Planner visible. By default,
Aspen Utilities Planner is not visible when an Aspen Utilities Planner file is
opened.
 Hide Aspen Utilities – allows you to hide Aspen Utilities Planner.
 Close Aspen Utilities – close the Aspen Utilities file and shutdown Aspen
Utilities Planner.
 Simulate Flowsheet – run a flowsheet simulation. This option is the
same as the run simulation in Aspen Utilities Planner with two important
additions: 1. before the simulation runs, values are sent from the
spreadsheet to Aspen Utilities Planner, and 2. when the run has finished
the latest values are retrieved from Aspen Utilities Planner.
 Run Reconciliation – runs data Reconciliation.
 Optimize Flowsheet – runs an optimization. As with Simulate Flowsheet,
values are sent from the spreadsheet to Aspen Utilities Planner before the
optimization and values are retrieved from Aspen Utilities Planner when
the optimization is complete.
 Simulation Menu
o Load Simulation Links – loads the Simulation Links command bar
and generates the Simulation Links worksheet if it not present.
94 5 Microsoft Excel Interface

o Send Values – this option retrieves the values of variables on the
Simulation Links worksheet and sends them to Aspen Utilities Planner
o Get Latest Values – this option retrieves the latest values from
Aspen Utilities Planner for the variables selected on the Simulation
Links worksheet.
 Reconciliation Menu
o Load Reconciliation – loads the reconciliation bar and generates the
Reconciliation worksheet if it not present.
o Get Latest Values – this option retrieves the latest values from
Aspen Utilities Planner for the variables selected on the Simulation
Links worksheet.
 Optimization Menu
o Get Optimization Results – when an optimization run is completed,
the results shown in the Simulation Links sheet are for the first period
only. To view the results from other periods, select this menu item and
input the period number of interest. The flowsheet re-simulates and
the results are displayed for that period.
o Editors… – displays the Profiles and Tariff Data editors.
 Refresh Data – updates the data shown in the spreadsheet.
At the bottom of the Aspen Utilities menu item is a list of the most recently
opened Aspen Utilities files. This recent file list is discarded when the Add-In
is uninstalled.
Open Aspen Utilities File
An Aspen Utilities file must be opened before any Aspen Utilities menu items
become available and before the Simulation Links worksheet can be
configured.
1 Select Open Aspen Utilities File from the Aspen Utilities menu item.
2 Use Browse to search for the file you want to open.
3 Click OK.
The status bar in Excel shows the full path name of the file being opened.
When the file is open the status area message changes to Ready.
If required, you can make Aspen Utilities Planner visible by selecting Show
Aspen Utilities from the Aspen Utilities menu.
Running a Simulation from
Excel
This section describes how to setup Excel to send and retrieve values from

Creating a Simulation Links worksheet
Simulation Links is used, as the name implies, to create links between Excel
and your Aspen Utilities Planner flowsheet (the .auf file).
You can add a simulation links worksheet by selecting the menu item Aspen
Utilities | Simulation | Load Simulation Links.
Note: If a Simulation Links worksheet already exists a new one will not be
added.
A blank Simulation Links worksheet is shown below:
There are two sections in the Simulation Links sheet: the left-hand side is
used for sending values to Aspen Utilities Planner and the right-hand side is
used to retrieve values from Aspen Utilities Planner.
Note: A Simulation Links command bar is added to the Excel menu area.
All information is saved with the spreadsheet. If you change the Aspen
Utilities Planner file in certain ways (e.g., renaming a block, removing a block,
changing the model by removing a variables, etc.), some links may become
invalid and these cells are highlighted yellow the next time the spreadsheet is
open. A yellow highlight indicates the block or variable in the simulation link
does not exist in the currently opened Aspen Utilities flowsheet.

Configuring Blocks and Variables for Input
to Aspen Utilities Planner
To configure blocks and variables to send to Aspen Utilities Planner follow
below steps:
1 Click on the left-hand side dropdown list to display all block names in the
flowsheet as shown below:
2 Select the block of interest and the name will be added to the first empty
row on the Send Values side.
3 Click Load Variables (see above figure).
4 Click on the Variable Name drop-down list to display all the variables
associated with the selected block. Select a variable and its name is
inserted next to the block name in the worksheet. An example of the
variable name list is shown below.

5 Enter the desired value in the Value cell.
6 Continue the above steps until all your input variables are selected. When
the data on the spreadsheet reaches the last couple of rows near the
bottom of the worksheet a line is automatically added.
7 By default, the value you enter must be in the current unit of measure
defined in Aspen Utilities Planner. You can enter a different unit of
measure in the Unit column (e.g., GJ/hr for energy flow, ton/hr for mass
flow, etc.). The value will be converted to the new unit when it is sent to
Aspen Utilities Planner. If you select the menu item Aspen Utilities |
Simulation | Send Values, the values are converted and sent without
executing simulation. This is done automatically when you simulate or
optimize the flowsheet. Take care when entering a different unit of
measure, that the string you enter is known to Aspen Utilities Planner.
Configuring Blocks and Variables for
Retrieval from Aspen Utilities Planner
Configuring blocks and variables to retrieve from Aspen Utilities Planner is
very similar to the procedure outlined in the previous section. Blocks and
variables to be retrieved from Aspen Utilities Planner are configured on the
right-hand side of the spreadsheet. Follow below steps:
1 Click on the third drop-down list from left to display all block names in the
flowsheet:
2 Select the block of interest and the name will be added to the first empty
row on the Retrieve Values side.
3 Click Load Variables (see above figure).

4 Click on the Variable Name drop-down list to display all the variables
associated with the selected block. Select a variable and its name is
inserted next to the block name in the worksheet. An example of the
variable name list is shown below:
5 By default, the displayed value is in the current unit of measure defined in
Aspen Utilities Planner. You can enter a different unit of measure in the
Unit column (e.g., GJ/hr for energy flow, ton/hr for mass flow, etc.). The
value will be converted to the new unit when it is retrieved from Aspen
Utilities Planner. If you select the menu item Aspen Utilities |
Simulation | Get Latest Values, the values are retrieved and converted
immediately. This is done automatically when you simulate or optimize the
flowsheet. Take care when entering a different unit of measure, that the
string you enter is known to Aspen Utilities Planner.

Mapping Variable Values to the Excel
Flowsheet
There are many advantages when using Microsoft Excel to run Aspen Utilities
Planner. One advantage is that it allows you to decompose complex
flowsheets into sub-flowsheets and draw them on separate worksheets. You
can then map variables from the Simulation Links worksheet to the cells in
the sub-flowsheet drawing in an intuitive way. A simple boiler model is used
here to illustrate this:
1 Starting with a new blank worksheet, draw a boiler and associated
streams using the drawing tools provided with Excel. It might look like:
2 Place the mouse cursor in the cell that you want to map to a Simulation
link and type = in the cell (cell E17 in the example above).
3 Switch to Simulation Links worksheet and click on the Value column for
the variable to map. Press the Enter key and Excel links the cells in the
two worksheets.
Note: The value column you should choose for the variable to map is the
value column in Retrieve latest values from Aspen Utilities form on the
right side.
4 Repeat these steps until all Simulation links have been mapped to your
flowsheet drawing.

By doing this, cell values in your flowsheet drawing will change when the
variable values change in the Simulation Links sheet – that is, when Get
Latest Values is selected or a flowsheet simulation or optimization is
performed.
Note: The unit of measure is not always shown after mapping. The units
fields in the table are used to display/send values in units of measure that
are different than the flowsheet. If the Units field is blank, values are sent
to or retrieved from the flowsheet with no unit conversion. If the Units
field has a string (UOM), the value is sent to or retrieved from the
flowsheet along with the UOM. Aspen Modeler attempts to convert the
value.
Running Data Reconciliation
from Excel
Many factors can affect the quality of data collected from the plant. Some
places in the plant may not have meters installed and others may have
meters that are malfunctioning. These data uncertainties cause the mass and
energy balances in the plant model to become unbalanced. In order to
reconcile the values calculated by the flowsheet models with those collected
from the plant, a data reconciliation tool is provided in Aspen Utilities. Before
using this tool in Aspen Utilities, you are encouraged to read the related
sections in the Aspen Custom Modeler User Guide. From the Aspen Utilities
Planner menu select Help | Aspen Custom Modeler Topics. Refer to the
online help on Estimation in this guide.

With the Aspen Utilities Planner Excel Interface, you can set up and run the
data reconciliation problem.
Accessing Reconciliation Worksheet
You set up the reconciliation problem in a Reconciliation worksheet. If your
existing Excel file does not contains a Reconciliation worksheet, you can
create one by selecting the menu item Aspen Utilities | Reconciliation |
Load Reconciliation:
A new worksheet named Reconciliation will be added to your workbook:
The Reconciliation worksheet has a Reconciliation command bar that is used
to set up the reconciliation problem. This is described in the next section.

Configuring Blocks and Variables for
Reconciliation
To reconcile the flowsheet model, you must specify which data are measured,
the quality of the data, and which model variables need to be reconciled.
Follow below steps to set up the information in the Reconciliation worksheet:
1 Click on the Model Names drop-down list to display all block names in the
flowsheet. Select the block in which the data measurement is located.
2 Click Load Variables.
3 Click on the Variable Name drop-down list to display all variables for the
selected block. Select the variable name that represents the measured
data.
4 The block and variable names along with its data will appear in the
worksheet as shown below:
Repeat the above steps until all desired variables are configured.
The columns in the Reconciliation worksheet are:
o Value - shows the current value in the flowsheet and will show the
reconciled value after the reconciliation run is executed.
o Units - indicates the unit of measurement used for the selected
variable in the flowsheet and can be changed. Take care when
entering a different unit of measure, that the string you enter is known
to Aspen Utilities Planner.
o Estimate - is where you enter the meter reading or the estimated
number.
o Variance/Relative/Confidence - indicates the type of weighting
methods used in the reconciliation. The weighting method can be

changed by selecting from the Weighting Method list on the
Reconciliation command bar.
o Add - indicates whether the selected variable in the reconciliation
worksheet is added into the model and reconciled. Y means to include
the variable and N means to exclude the variable.
o Spec - indicates the current specification of the selected variable:
Fixed or Free.
Note: The reconciliation problem must include at least one fixed variable.
o Lower Bound and Upper Bound - indicate the range that variables
are allowed to vary during the reconciliation run.
o Absolute Error - indicates the absolute difference between the
estimated value and the calculated model value.
o % Error - indicates the percentage difference between the estimated
value and the calculated model value.
Once the reconciliation sheet is configured, you can reconcile the flowsheet by
selecting the menu item Aspen Utilities | Run Reconciliation.
Here are a few tips that may help you set up the reconciliation problem:
1 If an associated variable that is connected to a reconciled variable is fixed
then include the associated variable with a small weight.
For example, if fuel molar flow is measured and the fuel mass flow is fixed
in the simulation, include both fuel mass flow and molar flow in the
estimation. The weight of fuel mass flow should be small.
2 Interrelated variables cannot be reconciled independently.
For example, a mass balance equation would have the form: A + B + C =
D. If A, B and C are reconciled in the above equation and D has a status of
fixed in the simulation then include D with a small weight in estimation.
3 Do not constrain free variables and place sensible bounds on reconciled
variables (fixed variables).
4 Make sure the steady state simulation runs OK before using data
reconciliation.
Running Optimization from
Excel
The Aspen Utilities Planner Excel interface also allows you to optimize your
flowsheet. As is the case in optimizing from within the Aspen Utilities Planner
product, you should configure the utility demands and equipment availability
profiles as well as tariff data using the Profile and Tariff Editors. These can be
accessed by selecting the menu item Aspen Utilities | Optimization |
Editors….
In addition, the Excel interface has two built-in functions that are
automatically called before and after the optimization: BeforeOptimise and
FlowsheetUpdate. These are present to allow any user-specific tasks before
and after flowsheet optimization.

Performing User Specific Tasks before
Optimization
You may want to conduct some specific tasks before doing an optimization,
such as running simulation, reconciling the flowsheet, etc. The BeforeOptimise
function can be used to do these tasks. Follow below steps to execute
BeforeOptimise function:
1 In Excel, select Tools | Macros | Visual Basic Editor to display the
Excel Visual Basic Editor.
2 Double-click on the Simulation Links sheet in the tree view and add the
function BeforeOptimise in the source code window as shown below:
You can put the tasks you want to run before optimization inside this
BeforeOptimise function. These tasks may, of course, call Excel functions,
other functions you create, or Aspen Utilities functions.

Producing Optimization Results and Tariff
Information from Aspen Utilities
One of the most common tasks is to retrieve optimization results from Aspen
Utilities Planner back to Excel. Follow these steps to configure a worksheet to
retrieve Aspen Utilities Planner results.
1 Click Tools | Macros | Visual Basic Editor to display the Excel Visual
Basic Editor.
2 Double-click on the Simulation Links sheet in the tree view and add
function FlowsheetUpdate in the source code window as shown below.
Here, functions MPUpdate and CostsUpdate are two built-in functions in
the Aspen Utilities Planner Excel Add-In that transfer the results and
costing information from Aspen Utilities Planner to Excel worksheet:
3 Add a worksheet in your workbook and name it MP Results. Configure
the worksheet so it has the column header names, highlighting, etc., as
shown below.
An even easier way to add the worksheet is by running an optimization
(select Aspen Utilities | Optimize Flowsheet). When the optimization
completes, the function MPUpdate called in FlowsheetUpdate will
automatically create and configure the MP Results worksheet.

4 Enter the Block ID and Port ID and corresponding legend.
Refer to the Configuring Blocks and Variables for Retrieval from Aspen
Utilities section earlier in this chapter for how to determine valid Block and
Port IDs.
5 Enter the desired unit of measure you want the value displayed in (the
Units column) and give the conversion factor that converts the value from
the current unit in Aspen Utilities Planner to this unit (the Conversion
Factor column):
Value2  CF Value1
Where:
Value2 = number in the desired unit
Value1 = number in the current unit in Aspen Utilities Planner
For example, if current unit for mass flow in Aspen Utilities Planner is
ton/hr and you want to show the number in Mlb/hr, the conversion factor
is 2.21 (Mlb/hr = 2.21 ∙ton/hr).

6 Run optimization and the results will be populated into the worksheet as
shown here:

In addition to the MPResults worksheet, a new worksheet named Costs
is added to the workbook as a result of calling
Application.Run(“CostsUpdate”)
In the function FlowsheetUpdate.This worksheet lists all the utilities tariff
information as shown below.
Of course, the FlowsheetUpdate function is not limited to calling these two
built-in functions. You can add any tasks you want to run after
optimization inside this function. These tasks could call Excel functions,
other functions you create, or Aspen Utilities functions.
Obtaining Results from Multi-Period
Optimization
After a multi-period optimization has run, the Aspen Utilities Planner Excel
interface retrieves and displays the results for period 1. To obtain the results
for other periods, select Aspen Utilities | Optimization | Get
Optimization Results from the Aspen Utilities menu. A form is displayed
which allows you to enter the period number to retrieve. The simulation is
rerun and results are displayed for that optimization period.

6 Aspen Utilities Planner
Reference
Model Library
An Aspen Utilities flowsheet consists of a number of Models.
 Models are joined together by Streams.
 Streams are connected to the Models by Ports.
In the majority of cases the specification takes place in the models.
Each model has two areas for specifying the equipment. Most of the
specifications for the simulation mode are made in the Summary table
(loaded by double-clicking on the model).
It may also be necessary to provide constraints for equipment used in the
optimization mode. These constraints should be viewed as the physical limits
of a piece of equipment. For example, a boiler has a maximum steam
generation capacity. It also has a minimum turndown which can be translated
into a minimum steam flow if the boiler is in use.
Each model has various limits that can be applied to it in the optimization
mode. These limits are accessed in the Optimization_Limits table. All models
have these optimization limits specified with a default value. You can replace
the default values as required.
During optimization if the model is ‘on’ (in operation) the constraints set in
the Optimization_Limits table are always obeyed. If a block is ‘off’ during the
optimization, any minimum constraints are ignored. The only blocks that
cannot be switched off during optimization are Feed and Demand blocks.
It is possible to put optimization limits on streams, however, it is advised not
to do this unless the constraint is associated with the pipe work rather than
equipment.
6 Aspen Utilities Planner Reference 111

List of Models
The following table lists the Aspen Utilities Planner models and their
categories:
Model Name Model Category
Air_Mix Headers
AirMultiplier Multipliers
AS_HeatEx Heat_Exchangers
Boiler Fuel_Models
Chiller Heat_Exchangers
Combustor Fuel_Models
Condenser Heat_Exchangers
Deaerator Steam_Models
DemandAir Demands
DemandFuel Demands
DemandPower Demands
DemandSteam Demands
Desuperheater Steam_Models
DFBoiler Fuel_Models
DriveList Pumps
Dual_Fuel_Demand Demands
FeedAir Feeds
FeedFuel Feeds
FeedPower Feeds
FeedSteam Feeds
Fuel_Vap Heat_Exchangers
FuelHeader Headers
FuelMultiplier Multipliers
GasTurbine Fuel_Models
GeneralModel Templates
Heater Heat_Exchangers
Heater_1 Heat_Exchangers
HRSG Fuel_Models
MultiStageTurbine Steam_Turbines
PowerHeader Headers
PowerMultiplier Multipliers
Pump Pumps
PumpList Pumps
SteamEjector Steam_Models
SteamHeader Headers
SteamMultiplier Multipliers
Stm_Flash Steam_Models
Stm_Mix Steam_Models
112 6 Aspen Utilities Planner Reference

Stm_Turb Steam_Turbines
Stm_Valve Steam_Models
WW_HeatEx Heat_Exchangers
AirAirExchanger Heat_Exchangers
FuelMixer Fuel_Models
FuelSwitch1toN Fuel_Models
Burner Emissions_Model
EmissionsChemney Emissions_Model
EmissionsNode Emissions_Model
EmissionsSwitch Emissions_Model
NOXEstimator Emissions_Model
General Model Structure
All models have one or more inlet ports and one or more outlet ports. In most
models you can connect multiple streams to one port. In some models only
one stream can be connected to either the inlet or outlet port and where this
is the case it is stated in the model description.
The model has the following general structure:
Model Specific
Calculations
Mixer
Mixer
Splitter
Splitter
Inlet Port
(Type 1)
Inlet Port
(Type 2)
Outlet Port
(Type 1)
Outlet Port
(Type 2)

Where a port is of a single stream type, the associated splitter or mixer is not
required.
Variable Naming Convention
The variable naming convention used within a model is as follows:
Portname(“PortnameN”).Variable Name
Where:
N = number of the port if there are a number of ports of the same type.
For the vast majority of cases N is 1.
Where there are multiple streams connecting to a port the variable naming
convention is:
Portname(“PortnameN”).Connection(“X”).Variable Name
Where:
X = name of the stream.
Standard Variable Names in Models
Variable Description
F Flow. This is mass flow for all streams except fuel streams
where it is heat flow.
h Enthalpy.
P Pressure.
T Temperature.
vf Steam vapor fraction.
StartUpCost Cost of starting up equipment.
ShutDownCost Cost of shutting down equipment.
StartUpTime Time to start up equipment.
ShutDownTime Time to shut down equipment.
DoOnOff Allow optimizer to switch the unit on/off.
DoStartStop Startup/Shutdown constraints to be used.
DoSteamReserve Include steam reserve in optimization.
CI Carbon Index.
F_mass Fuel Mass Flow.
F_mol Fuel Molar Flow.
MW Molecular Weight.
OD Stoichiometric Oxygen Demand.
SI Sulfur Index.
CO2 Carbon Dioxide concentration.
SOx Oxides of Sulfur concentration.
O2 Oxygen concentration.
Pout Outlet Pressure (Global model parameter).
Tout Outlet Temperature (Global model parameter).
DelP Pressure drop.

Duty Heat Duty.
Power Power.
Ports and Streams
Four port types have been defined:
 Steam Port (also used for water).
 Fuel Port.
 Power Port.
 Air Port.
Four stream types have been defined:
 Steam Stream which is used for steam and water streams.
 Fuel Stream.
 Air Stream used for air and for flue gas.
 Power Stream.
Streams can only connect ports of the same type. Therefore a steam stream
can only connect two steam ports. When a stream is dragged onto the
flowsheet only the appropriate ports are highlighted for connection. It is not
possible to connect to the incorrect port type.
Specifying Capacity Limits
Two types of equipment constraints can be specified in Aspen Utilities
Planner; namely equipment design constraints and temporary equipment
constraints. In the optimization, if both constraints are specified for a
particular equipment, then the lower bounds would be determined by the
minimum values whichever is larger, while the upper bound is determined by
the maximum values whichever is smaller.
Equipment Design Constraints
Equipment design constraints should be specified in the Aspen Utilities file
using the Optimization_Limits table associated with each block as shown in
the table below. Care should be taken not to over constrain the problem as
this may results in infeasible solutions.

Temporary Equipment Constraints
Temporary equipment constraints should be specified in the Availability Profile
for the piece of equipment.
Feeds
Feed blocks are used to represent/define the supply of utilities from outside
the boundary of the utility system model. There are four utility supply blocks
corresponding to the four stream types. Only one stream can be connected to
each feed block.
It is possible to set minimum and maximum flow limits on all feed blocks. It is
not possible to switch off feed blocks during optimization.
FeedSteam
FeedSteam

Description
The FeedSteam model is used to model the external supply of steam or water
to the utility system. This may be purchased steam from an external supplier,
steam generated in a process unit or the supply of make-up water.
Inlet Ports
There are no inlet ports.
Outlet Ports
Port Name Description Multiple Streams Allowed
SteamOut(“SteamOut1”) Outlet Stream No
Specifications
Tout Temperature of the steam/water supply.
Pout Pressure of the steam/water supply.
SteamOut(“SteamOut1”).F Flowrate of the steam/water supply.
Note: The flowrate: SteamOut(“SteamOut1”).F, of the steam feed is a fixed
variable (value must be specified), but may be switched to become a free
variable to satisfy degree of freedom requirements.
FeedFuel
FeedFuel
Description
The FeedFuel model is used to model the external supply of fuel to the utility
system. This steam may be purchased fuel from an external supplier or fuel
generated in a process unit.
Inlet Ports

Outlet Ports
FuelOut(“FuelOut1”) Outlet Stream No
Specifications
CVout Calorific value of the fuel.
MWout Molecular Weight of the fuel.
OD Oxygen demand of the fuel.
FuelOut(‘FuelOut1”).F The heat flow of the fuel.
CI Optional. Carbon Index.
SI Optional. Sulfur Index.
Notes:
 The oxygen demand of a fuel is the mass ratio oxygen to fuel under
stoichiometric conditions.
 The enthalpy flow of the fuel feed: FuelOut(“FuelOut1).F, is a fixed
variable by default, but may be switched to become a free variable to
satisfy degree of freedom requirements.
 If emissions (CO2 and SOX) are to be calculated within the model then the
Carbon Index (CI) and the Sulphur Index (SI) must be specified. Both of
these indices are the mass ratio of the emission to fuel.
FeedPower
FeedPower
Description
The FeedPower model is used to model the external supply of power to the
utility system. This steam may be purchased power from an external supplier
or power generated in a process unit.
Inlet Ports

Outlet Ports
PowerOut(“PowerOut1”) Outlet Stream No
Specifications
PowerOut(“PowerOut1”).Power Power Supply.
Note: The power flow: PowerOut(“PowerOut1”).Power, is specified as fixed
by default, but may be switched to become a free variable to satisfy degree of
freedom requirements.
FeedAir
FeedAir
Description
The FeedAir model is used to model the external supply of air to the utility
system.
Inlet Ports
Outlet Ports
AirOut(“AirOut1”) Outlet Stream No
Specifications
AirOut(“AirOut1”).F Mass flowrate.
Tout Temperature of the air.
O2 Oxygen content by mass.

Note: The mass flow of the air: AirOut(“AirOut1”).F, is a fixed variable by
default, but may be switched to become a free variable to satisfy degree of
Demands
Demand blocks are used to represent/define the demand of utilities from
outside the boundary of the utility system model. There are four utility
demand blocks corresponding to the four stream types. Only one stream can
be connected to the demand blocks
It is possible to set minimum and maximum flow limits on all demand blocks.
It is not possible to switch demand blocks off during optimization.
DemandSteam
DemandSteam
Description
The DemandSteam model is used to model demand for steam or water
external to the utility system.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Stream No
Outlet Ports
There are no outlet ports.
Specifications
SteamIn(“SteamIn1”).F Steam/Water mass flowrate.
Notes:
 The mass flow of steam, SteamIn(“SteamIn1”).F, is a fixed variable by
default, but may be switched to become a free variable to satisfy degree
of freedom requirements.
 The temperature, pressure, vapor fraction and enthalpy of the steam are
inherited from the outlet of the upstream block. These variables should
never be fixed.

DemandFuel
DemandFuel
Description
The DemandFuel model is used to model demand for fuel external to the
utility system.
Inlet Ports
FuelIn(“FuelIn1”) Inlet Stream No
Outlet Ports
Specifications
FuelIn(“FuelIn1”).F Fuel Heat Flow.
Notes:
 The enthalpy flow of the fuel: FuelIn(“FuelIn1”).F, is a fixed variable by
 The calorific value, molecular weight, oxygen demand, carbon index and
sulphur index are inherited from the outlet of the upstream block. These
variables should never be fixed.
DemandPower
DemandPower
Description
The DemandPower model is used to model demand for power external to the
utility system.

Inlet Ports
PowerIn(“PowerIn1”) Inlet Stream No
Outlet Ports
Specifications
PowerIn(“PowerIn1”).Power Power Demand.
Note: The power demand: PowerIn(“PowerIn1”).Power, is a fixed variable
by default, but may be switched to become a free variable to satisfy degree of
DemandAir
DemandAir
Description
The DemandAir model is used to model demand for air external to the utility
system.
Inlet Ports
AirIn(“AirIn1”) Inlet Stream No
Outlet Ports
Specifications
AirIn(“AirIn1”).F Air mass flowrate.

Notes:
 The mass flow of the air: AirIn(“AirIn1”).F, is a fixed variable by
 The enthalpy, oxygen, CO2 and SOX content of the air are inherited from
the upstream block. These variables should never be fixed.
Dual_Fuel_Demand
Dual_Fuel_Demand
Description
This block is used to represent a demand for fuel, but where one of two fuels
or a mix of the two fuels can satisfy the demand.
Inlet Ports
FuelIn(“FuelIn1”) Inlet Stream 1 No
FuelIn(“FuelIn2”) Inlet Stream 2 No
Outlet Ports
Specifications
FuelIn(“FuelIn1”).F Heat Flow of Fuel 1.
FuelIn(“FuelIn2”).F Heat Flow of Fuel 2.
Optimization Limits
MinFuelDuty_1/MaxFuelDuty_1 Minimum/maximum Fuel1 Duty.
MinFuelDuty_2/MaxFuelDuty_2 Minimum/maximum Fuel2 Duty.
Ratio_min/Ratio_max Minimum/Maximum ratio of Fuel1 to Fuel2
duty.
Note: The calorific value, molecular weight, oxygen demand, carbon index
and sulphur index for each fuel are inherited from the outlet of the upstream
blocks. These variables should never be fixed.

Headers
There are four headers corresponding to the four stream types.
SteamHeader
Steamheader
Description
The steam header block is used to represent the site steam header systems.
It can also be used to split a steam/water stream. The model allows multiple
feeds and products.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Streams Yes
Outlet Ports
SteamOut(“SteamOut1”) Outlet Streams Yes
Blowsteam(“BlowSteam1”) Vent Flow No
WaterOut(“Blowdown”) Blowdown Flow No
Specifications
Tout Nominal Header Temperature.
Pout Nominal Header Pressure.
BlowSteam(“BlowSteam1”).F Vent Steam Flow (Default value is 0).
BDRatio Blowdown Ratio (Default value is 0).
Optimization Limits
MinFlow/MaxFlow Minimum and maximum flow of steam/water in
the header.
MinBDFlow/MaxBDFlow Minimum and maximum blowdown flow.
MinVentFlow/MaxVentFlow Minimum and maximum vent flow.

Note: The heat loss and pressure drop in the header are calculated. The
enthalpy and vapor fraction of outlet are calculated from the temperature and
pressure specification.
FuelHeader
Fuelheader
Description
The fuel header block is used to represent the site fuel distribution system.
The model allows multiple feeds and consumers. The property (MW, OD, CV,
CI, SI) of the fuel within the header is based on an average of the feeds.
These properties are transferred to the outlet streams.
Inlet Ports
FuelIn(“FuelIn1”) Inlet Streams Yes
Outlet Ports
FuelOut(“FuelOut1”) Outlet Streams Yes
Specifications
No specifications required.
Optimization Limits
MinFuelDuty/MaxFuel Duty Minimum and maximum total fuel (heating duty) in
the header.
PowerHeader
PowerHeader

Description
The power header block is used to represent the site power distribution
system. The model allows multiple feeds and consumers.
Inlet Ports
PowerIn(“PowerIn1”) Inlet Streams Yes
Outlet Ports
PowerOut(“PowerOut1”) Outlet Streams Yes
Specifications
Optimization Limits
MinPower/MaxPower Minimum and maximum total power in the header.
Air_Mix
Air_Mix
Description
The Air_Mix model is used to mix air flows.
Inlet Ports
AirIn(“AirIn1”) Inlet Streams Yes
Outlet Ports
AirOut(“AirOut1”) Outlet Streams No
Specifications

Optimization Limits
MinFlow/MaxFlow Minimum and maximum total air flow in the mixer.
Steam Models
Deaerator
Description
The deaerator is used for deaeration of water for steam generation. The
deaerator model allows multiple water feeds and a single steam feed. A single
boiler feed water stream is produced. You can also connect a vent stream.
The model calculates the amount of steam required to heat the feed water to
the saturated conditions at the deaerator operating pressure.
Ensure that the water and steam feeds are connected to the correct ports.
Inlet Ports
SteamIn(“SteamIn1”) Deaeration Steam No
WaterIn(“WaterIn1”) Water Feed Yes
Outlet Ports
WaterOut(“WaterOut1”) Water Outlet No
Blowsteam(“BlowSteam1”) Vent Flow No
Specifications
Pdeaer Deaerator operating pressure.
VR Vent Ratio.

Optimization Limits
MinBFWout/MaxBFWou
t
Minimum/maximum boiler feed water flow out of the
deaerator.
MinDFWin/MaxDFWin Minimum/maximum water flow to the deaerator.
MinSteam/MaxSteam Minimum/maximum steam flow to the deaerator.
MinVent/MaxVent Minimum/maximum vent flow.
Note: The vent ratio is specified as follows:
VR = Vent Steam/(Steam Feed- Vent Steam)
Stm_Valve
Stm_valve
Description
This model is used to reduce the pressure of a steam/water stream.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Stream No
Outlet Ports
Specifications
Psout Outlet Pressure.
Optimization Limits
MinFlow/MaxFlow Minimum/maximum flow through the valve.

Desuperheater
Description
This is used to model letdown stations where the steam is desuperheated.
The amount of water required to desuperheat the steam is calculated.
Ensure that the water and steam feeds are connected to the correct ports.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Steam No
WaterIn(“WaterIn1”) Desuperheating Water No
Outlet Ports
Specifications
Psout Outlet Pressure.
Tsout Outlet Temperature.
Optimization Limits
MinSteam/MaxSteam Minimum/maximum steam flow.
MinWater/MaxWater Minimum/maximum water flow.

Stm_Flash
Description
This is used to model flash drums. The model allows multiple steam streams
at the inlet. The block allows two outlet streams, a water stream, and a steam
stream, both at saturated conditions.
Ensure that the water and steam products are connected to the correct ports.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Steams Yes
Outlet Ports
SteamOut(“SteamOut1”) Flash Steam No
WaterOut(“WaterOut1”) Flash Condensate No
Specifications
Pflash Flash drum operating pressure.
Optimization Limits
MinFeedFlow/MaxFeedFlow Minimum/maximum total feed flow.
MinVapFlow/MaxVapFlow Minimum/maximum flash steam flow.
MinLiqFlow/MaxLiqFlow Minimum/maximum flash condensate flow.

Stm_Mix
Description
This model is used to mix steam/water streams. The condition of the outlet
stream is calculated from an energy and mass balance of the feeds.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Steams Yes
Outlet Ports
SteamOut(“SteamOut1”) Flash Steam No
Specifications
Optimization Limits
MinFlow/MaxFlow Minimum/maximum total flow.
SteamEjector
Description
This model acts as a steam thermocompressor. The outlet steam pressure
and entrainment ratio need to be specified, and the model calculates the inlet
HP and LP steam required.

Inlet Ports
SteamIn(“HPSteamIn”) Inlet Steam No
SteamIn(“LPSteamIn”) Inlet Steam No
Outlet Ports
SteamOut(“IPSteamOut”) Outlet Steam No
Specifications
EntrainmentRatio Ratio of LP to HP inlet steam.
Optimization Limits
MinHPInletSteam/MaxHPInletSteam Minimum/maximum HP steam flow.
MinLPInletSteam/MaxLPInletSteam Minimum/maximum LP steam flow.
MinOutletSteam/MaxOutletSteam Minimum/maximum outlet steam flow.
Pumps
Pump
Description
The pump model is used to increase the pressure of a water stream. The
model allows multiple water feeds and one outlet. One or more power feeds
can also be added to the model.
The pump efficiency can be specified as a fixed value or as an efficiency
curve. The default efficiency method is Constant and in this case, you must
specify the efficiency (ConstEff).

Inlet Ports
PowerIn(“PowerIn1”) Inlet Power Yes
Outlet Ports
Specifications
Pout Outlet Pressure.
EffMethod Efficiency Method (default Constant).
ConstEff Fixed Efficiency (used if efficiency method is Constant).
NEffPoints Number of points on the efficiency curve (used is efficiency
method LookUpTable).
If LookUpTable is selected, you must enter the efficiency curve in the EffTable
form. A minimum of two points (NeffPoints) must be specified. The data is
entered as efficiency against volumetric flow through the pump.

Optimization Limits
PowerMin/PowerMax Minimum/maximum power to the pump.
FlowMin/FlowMax Minimum/maximum mass flow through the pump.
Note: If an efficiency curve is entered for the pump the minimum and
maximum mass flow limits are determined by the range of the efficiency
curve.
Drive List
Description
The drive list model is used to represent a number of motor/turbine drives
that can be used for a particular pump or group of pumps that have the same
service, e.g., cooling tower pumps. The model has both a single steam feed
and steam product, which are connected to each turbine drive in the list. This
means all drives included in the drive list have to be between the same steam
levels. The model also has a single power feed and power product. The power
product stream is connected to a single power demand (a pump or power
demand block).
Inlet Ports
SteamIn(“SteamIn1”) Inlet Streams No
PowerIn(“PowerIn1”) Inlet Power No

Outlet Ports
PowerOut(“PowerOut1”) Outlet Power No
Specifications
NoDrives Number of drives being represented 1-n.
DriveName(n) The name of each drive (Optional).
DriveOption(n) The type of drive either motor or turbine.
Psout The outlet pressure of the steam from the turbine drives
(Psout).
Shaftwork(n) The shaftwork of the drives.
SteamFlow_A(n) Constant for specifying efficiency of each turbine – base
unit ton/hr.
SteamFlow_B(n) Constant for specifying efficiency of each turbine – base
unit ton/hr/MW.
Efficiency(n) Efficiency of each motor.
Optimization Limits
MinWork(n)/MaxWork(n) Minimum/maximum shaftwork produced by a
specific drive.
MinShaftwork/MaxShaftwork Minimum/maximum shaftwork produced by the
block.
MinFlow/MaxFlow Minimum/maximum steam flow to the block.
MinPower/MaxPower Minimum/maximum power flow to the block.
Notes:
 The shaftwork should be supplied for n-1 drives. In simulation mode the
shaftwork for the remaining drive is calculated along with the steam
demand of the turbine drives and the power demand for the motor drives.
 For each of the turbine drives a set of constants must be supplied to
represent the efficiency of the turbine. The constants can be entered on
the SteamFlow_Constants table. The efficiency of the turbines are
represented as follows:
Steam Demand = SteamFlow_A + SteamFlow_B*Shaftwork
 In optimization mode the economic mix of drivers is calculated.

Pump List
Description
The pump list model represents one or more process pumps which have the
option of either a turbine or motor driver. The model allows only one steam
inlet and one steam outlet stream so pumps should be grouped together by
turbine drivers operating between the same steam levels. The model also
allows a single power feed.
The model does not have a power out port therefore it is not possible to
connect this model to another model on the Aspen Utilities flowsheet as in the
case of the drive list. Instead the power demand is specified directly in the
block for each pair of drives. For optimization, this power demand can be set
in the profiles data editor.
Inlet Ports
Outlet Ports
Specifications
NoPumps Number of pumps being represented 1-n.
PumpName(n) The name of each pump (Optional).
PumpOption(n) The default drive used for the pump.
Psout The outlet pressure of the steam from the turbine drives.
PowerRequired(n) The power required for each pump.
SteamFlow_A(n) Constant for specifying efficiency of each turbine – base
unit ton/hr.
SteamFlow_B(n) Constant for specifying efficiency of each turbine – base
unit ton/hr/MW.
Efficiency(n) Efficiency of each motor.

Optimization Limits
MinFlow/MaxFlow Minimum/maximum steam flow to the block.
MinPower/MaxPower Minimum/maximum power flow to the block.
Notes:
 For each of the turbine drives a set of constants must be supplied to
represent the efficiency of the turbine. The constants can be entered on
the SteamFlow_Constants table. The efficiency of the turbines are
represented as follows:
Steam Demand = SteamFlow_A + SteamFlow_B*PowerRequired
 In optimization mode the economic mix of drivers is calculated.
Turbines
Stm_Turbine
Description
This is used to model a single stage turbine. The isentropic efficiency can be
specified as a fixed value or as an efficiency curve. The default efficiency
method is Constant and you must specify the efficiency (ConstEff).
Inlet Ports
Outlet Ports

Specifications
Pout Outlet Pressure.
SteamOut(“SteamOut1”).F Flow of steam through the turbine.
ConstEff Fixed Efficiency (used if efficiency method is
Constant).
NEffPoints Number of points on the efficiency curve (used if
efficiency method LookUpTable).
If LookUpTable is selected then you must enter the efficiency curve in the
EffTable form. A minimum of two points (NeffPoints) must be specified. The
data is entered as flow against power generated in the turbine.
Optimization Limits
PowerMin/PowerMax Minimum/maximum power from the turbine.
FlowMin/FlowMax Minimum/maximum mass flow of steam through the
turbine.
If an efficiency curve is entered for the turbine the minimum and maximum
mass flow limits are determined by the range of the efficiency curve.
Note: The conditions (temperature and pressure) of the steam feed is
supplied by an upstream block. You can change the mass flow of steam
specification to a power specification by fixing variable
PowerOut(“PowerOut1”).Power or linking it to a power demand on
another block.

MultiStageTurbine
Description
This is used to model a multiple stage turbine. There are three ways to
specify the performance of multistage turbine: constant isentropic efficiency,
linear relation between power and mass flow and lookup table. The default
efficiency method is Constant and in this case, you must specify the efficiency
(ConstEff).
Inlet Ports
SteamIn(n) Inlet Streams Yes
Outlet Ports
SteamOut(n) Outlet Stream Yes
Specifications
nStages Number of Stages.
SPout(n) Outlet Pressure for stages.
SteamIn(n). Inlet flow of steam through the turbine (includes flow to any
induction stages).
SteamOut(n-1) Outlet flow of all Extraction stages.
ConstEff Fixed Efficiency (used if efficiency method is Constant).
STout(n-1) Outlet stage temperature (To be specified if efficiency method
is LookUpTable).
NeffPoints Number of points on the efficiency curve (used if efficiency
method LookUpTable).
You should specify the type of stages in the stage data form. A multistage
turbine with n stages has n-1 interstages.

The kInterstange can be used to linearly capture the effect of extraction flow
to nominal power after properly specify the Interstage.
 The kInterstage for induction Interstage type is used as:
nominalPower = LooUpTable(Steam Flow) – (kInterStage *
ExtractionFlow)
 The kInterstage for induction InterStage type is used as:
nominalPower = LookUpTable(Steam Flow) + (kInterStage *
InductionFlow)
 The kInterStage for “Both” Interstage type is used as:
nominalPower = LookUpTable(Steam Flow) + [kInterstage *
(InductionFlow – ExtractionFlow)]
For example, when the Interstage is specified as “Extraction”, the kInterstage
is used to correct the nominal power got from the steam flow by substracting
the product of extraction flow and kInterstage.
If Linear Efficiency method is selected, you must specify the slope and
intercept for the power calculation from steam flow for each stage.
If LookUpTable is selected, you must enter the efficiency curve in the
PerformanceData form. A minimum of two points (nSections) must be
specified. The data is entered as flow against power generated in the turbine.

Optimization Limits
MinInlet/MaxInlet Minimum/Maximum inlet flow to the turbine.
MinimumInduction(n-1) Minimum induction flow into the stage.
MaximumInduction(n-1) Maximum induction flow into the stage.
MinimumExtraction(n-1) Minimum extraction flow from the stage.
MaximumExtraction(n-1) Maximum extraction flow from the stage.
MinPassout/MaxPassout Minimum/maximum passout flow from the last
stage.
PowerMin/PowerMax Minimum/maximum power from the turbine.
sMinFlow(n)/sMaxFlow(n) Minimum/maximum steam flow through turbine
stage.
ExtrLimitConstant(n-1) Constant term in extraction flow constraint
equation.
ExtrLimitPowerTerm(n-1) Power term in extraction flow constraint
equation.
ExtrLimitInletSteamTerm(n-1) Inlet steam term in extraction flow constraint
equation.
ExtrLimitPassoutTerm(n-1) Passout steam term in extraction flow constraint
equation.
IndLimitConstant(n-1) Constant term in induction flow constraint
equation.
IndLimitPowerTerm(n-1) Power term in induction flow constraint equation.
IndLimitInletSteamTerm(n-1) Inlet steam term in induction flow constraint
equation.
IndLimitPassoutTerm(n-1) Passout steam term in induction flow constraint
equation.
If LookUpTable method is selected for the turbine, the minimum and
maximum mass flow limits are determined by the range of the efficiency
curve.

Notes:
 The conditions (temperature and pressure) of the steam feed are supplied
by an upstream block.
 You can change the mass flow of steam specification to a power
specification by fixing variable PowerOut(“PowerOut1”).Power or
linking it to a power demand on another block.
Heat Exchangers
AS_HeatEx
Description
This model is used to model either a steam generator using flue gas or as an
air/steam heat exchanger. You must specify the type of exchanger to be
modeled using HXMode. The options are either HX to model the air/steam
heat exchanger or StmGen to model the steam generator.
Inlet Ports
WaterIn(“WaterIn1”) Inlet Steam/Water Yes
AirIn(“AirIn1”) Inlet Air/Fluegas No
Outlet Ports
AirOut(“AirOut1”) Outlet Air/Fluegas No

Specifications
HXMode Heat exchanger type to be modeled.
Tsout Temperature of the water leaving the exchanger. Required only
for HX mode.
DelPs Steam side pressure drop.
Optimization Limits
MinStmFlow/MaxStmFlow Minimum/maximum steam flow.
MinAirFlow/MaxAirFlow Minimum/maximum air flow.
Qmin/Qmax Minimum/maximum duty.
Tcinmin/Tcinmax Minimum/maximum temperature of the cold
stream entering the block.
Tcoutmin/Tcoutmax Minimum/maximum temperature of the cold
stream leaving the block.
Thinmin/Thinmax Minimum/maximum temperature of the hot
stream entering the block.
Thoutmin/Thoutmax Minimum/maximum steam flow.
Notes:
 In StmGen mode, the duty of the steam generator is calculated assuming
the steam outlet conditions are saturated vapor. The temperature and
enthalpy of outlet air stream is calculated by heat balance. It is assumed
that the flow and conditions of both the air and water streams are
specified in upstream blocks, if not you must also specify these.
 In HX mode, you can set the Tsout specification to free and fix either the
duty on the exchanger (Duty) or the temperature of the air leaving the
exchanger (Taout).
Chiller
Description
The air chiller model represents an air cooler using refrigeration. The
refrigeration system is not modeled and the refrigeration system utility

requirements are calculated using factors that relate the chiller duty to the
steam and power requirements. The temperature of the outlet air stream is
specified. A heat balance is not carried out on the block.
Inlet Ports
SteamIn(“SteamIn1”) Inlet Steam/Water No
AirIn(“AirIn1”) Inlet Air No
Outlet Ports
WaterOut(“WaterOut1”) Steam Condensate No
AirOut(“AirOut1”) Outlet Air No
Specifications
DelP Pressure drop on the steam side.
Tsout The temperature of the steam/water leaving the refrigeration
system.
Taout The temperature of the air leaving the chiller.
StmFact The steam factor, which is defined as the mass flow of steam
required per unit of cooling duty. The default units are therefore
ton/GJ.
PowFac The power factor, which is defined as the power demand per unit
of cooling duty. The default units are therefore MW∙hr/GJ.
Optimization Limits
PowerMin/PowerMax Minimum/maximum power.
Condenser

Description
This model is used to condense steam. The product stream is saturated water
at the outlet pressure of the condenser.
Inlet Ports
FuelIn(“FuelIn1”) Inlet Fuel No
Outlet Ports
WaterOut(“WaterOut1”) Steam Condensate No
FuelOut(“FuelOut1”) Fuel No
Specifications
Optimization Limits
FuelVap
Description
This model is used to calculate the amount of steam that is required to
vaporize a liquid fuel stream. It is not a rigorous heat balance, as the
properties of the fuel are not modeled. Instead, you must specify a mass ratio
of steam to fuel required to heat and vaporize the fuel steam.

Inlet Ports
Outlet Ports
WaterOut(“WaterOut1”
Steam Condensate No
)
Specifications
Optimization Limits
MinHFuel/MaxHFuel Minimum/maximum fuel heat duty.
Heater
Description
This model is used to heat water or steam. It is represented as a single sided
heat exchanger with a single steam feed in and a single steam feed out. The
duty of the heater must be fixed and the data is supplied via the profiles
database.
Inlet Ports

Outlet Ports
SteamOut(“SteamOut1”) Outlet Steam/Water No
Specifications
Duty Heat exchanger duty.
Optimization Limits
Heater_1
Description
This model is used to heat water or steam. It is represented as a single sided
heat exchanger with multiple steam feeds in and a single steam feed out. The
outlet temperature of the heater must be fixed.
Inlet Ports
Outlet Ports
SteamOut(“SteamOut1”) Outlet Steam/Water No
Specifications
Tsout Outlet steam/water temperature.

Optimization Limits
WW_HeatEx
WW_HeatEx
The model is used to exchange heat between two water/steam streams. The
model allows multiple water/steam feeds and single product streams. You
must ensure you have connected the feed and product streams to the correct
ports (hot or cold side).
Inlet Ports
WaterIn(“ColdWaterIn”) Inlet cold water Yes
WaterIn(“HotWaterIn”) Inlet hot water Yes
Outlet Ports
WaterOut(“ColdWaterOut”) Outlet cold water No
WaterOut(“HotWaterIn”) Outlet cold water No
Specifications
DelPhw Pressure drop on the hot water side.
DelPcw Pressure drop on the cold water side.
Thwout Hot water side outlet temperature.
Optimization Limits
Tcwinmin/Tcwinmax Minimum/maximum temperature of the cold water
entering the block.
Tcwoutmin/Tcwoutmax Minimum/maximum temperature of the cold water
leaving the block.
Thwinmin/Thwinmax Minimum/maximum temperature of the hot water
entering the block.

Thwoutmin/Thwoutmax Minimum/maximum temperature of the hot water
leaving the block.
MinCWFlow/MaxCWFlow Minimum/maximum hot water flow to the block.
MinHWFlow/MaxHWFlow Minimum/maximum cold water flow to the block.
Qmin/Qmax Minimum/maximum duty of the block.
Notes:
 The default specification on this block is fixed hot outlet temperature. A
deviation from the default specifications requires changes to be made to
the type of flash being used by the model.
 Use of default flash type and any other specification than default causes
the model to not converge or give erroneous results.
Some other common specifications and the changes that are required are
listed below. The changes can be made in the Flash_Type form.
 Default - Fixed Hot Outlet Temperature
o Cold_Outlet.FlashMode SetPH
o Hot_Outlet.FlashMode SetPT
 Fixed Cold Outlet Temperature
o Cold_Outlet.FlashMode SetPT
o Hot_Outlet.FlashMode SetPH
 Condensing Steam
o Hot_Outlet.FlashMode SetPV
 Fixed Duty
o Hot_Outlet.FlashMode SetPH
Duty should be a positive number during specification.

AirAirExchanger
Description
The model is used to exchange heat between two air streams. The model
allows a single air feed in and single outlet stream. You must ensure you have
connected the feed and product streams to the correct ports (hot or cold
side).
Inlet Ports
AirIn(“ColdIn”) Inlet cold air port No
AirIn(“HotIn”) Inlet hot air port No
Outlet Ports
AirOut(“ColdOut”) Outlet cold air port No
AirOut(“HotIn”) Outlet hot air port No
Specifications
Duty Heat Duty.
Optimization Limits
MinColdAirFlow/MaxC
oldAirFlow
Minimum/Maximum cold air flow.
MinHotAirFlow/MaxHo
tAirFlow
Minimum/Maximum hot air flow.
TColdAirInMin/TColdAi
rInMax
Minimum/Maximum cold air inlet temperature.
THotAirInMin/THotAirI
nMax
Minimum/Maximum hot air inlet temperature.
TColdAirOutMin/TCold
AirOutMax
Minimum/Maximum cold air outlet temperature.
THotAirOutMin/THotAi
rOutMax
Minimum/Maximum hot air outlet temperature.

Qmin/Qmax Minimum/Maximum heat duty (only used when duty is
specified as fixed variable)
Multipliers
There are four Multipliers corresponding to the four stream types.
SteamMultiplier
Description
The steam multiplier block provides a quick and simple mechanism for
augmenting or decreasing the flowrate of steam in a stream by a fixed factor.
The model supports multiple feed streams but only a single outlet stream.
Inlet Ports
Outlet Ports
Specifications
Multiplier Multiplication factor applied to outlet.
Optimization Limits
MinFlow Minimum inlet steam flow.
MaxFlow Maximum outlet steam flow.
Note: There is no heat loss and pressure drop in the block, and all the
properties of the outlet stream are calculated from the mixed inlet stream.

FuelMultiplier
Description
The fuel multiplier block provides a quick and simple mechanism for
augmenting or decreasing the flowrate of fuel in a stream by a fixed factor.
Inlet Ports
FuelIn(“FuelIn1”) Inlet Streams Yes
Outlet Ports
FuelOut(“FuelOut1”) Outlet Stream No
Specifications
Optimization Limits
MinFuelDuty Minimum inlet fuel flow.
MaxFuelDuty Maximum outlet fuel flow.
Note: All the properties of the outlet stream are calculated from the mixed
inlet stream.set to those of the inlet stream.
PowerMultiplier

Description
The power multiplier block provides a quick and simple mechanism for
augmenting or decreasing the flowrate of power in a stream by a fixed factor.
Inlet Ports
PowerIn(“PowerIn1”) Inlet Streams Yes
Outlet Ports
PowerOut(“PowerOut1”) Outlet Stream No
Specifications
Optimization Limits
MinPower Minimum inlet power flow.
MaxPower Maximum outlet power flow.
AirMultiplier
Description
The air multiplier block provides a quick and simple mechanism for
augmenting or decreasing the flowrate of air in a stream by a fixed factor.
Inlet Ports
AirIn(“AirIn1”) Inlet Streams Yes
Outlet Ports

AirOut(“AirOut1”) Outlet Stream No
Specifications
Optimization Limits
MinFlow Minimum inlet air flow.
MaxFlow Maximum outlet air flow.
Note: There is no heat loss and pressure drop in the block, and all the
properties of the outlet stream are calculated from the mixed inlet stream.
Fuel Models
Boiler
Description
This is a simplified boiler model. A rigorous heat and material balance is
calculated. It is possible to calculate the boiler fan power requirement within
the model and in this case, you can also connect a power feed to the model.
The efficiency can be specified as a fixed value or as an efficiency curve. The
default efficiency method is Constant and in this case you must specify the
efficiency (ConstEff).

Inlet Ports
WaterIn(“BFW”) Inlet BFW Yes
FuelIn(“Fuel”) Inlet Fuel No
Outlet Ports
SteamOut(“VHPSteam”) Steam Production No
WaterOut(“Blowdown”) Blowdown No
AirOut(“Fluegases”) Fuelgas No
Specifications
SteamOut(“VHPSteam”).F Steam generation rate.
EffMethod Efficiency method. The default is Constant. The
options are Constant or LookUpTable.
BDRate Blowdown rate.
O2out Oxygen content of the fluegas.
Pdrop_Gen Pressure drop in the steam drum and economizer.
Pdrop_SH Pressure drop in the superheater.
Tboiler Temperature of the outlet steam.
FanCoeffB Coefficients for calculating the boiler fan power
requirement. This is optional.
FanCoeffC Coefficients for calculating the boiler fan power
If LookUpTable is selected as the efficiency method, you must enter the
efficiency curve in the EffTable form. A minimum of two points (NeffPoints)
must be specified. The curve is in the form efficiency against steam flow.
Optimization Limits
MinFuelDuty/MaxFuelDuty Minimum/maximum fuel flow (enthalpy).
If an efficiency curve is used then the optimization limits for the
minimum/maximum steam flow are defined as the range of the efficiency
curve.
Note: There is a state parameter defined in the model called
OperationalStatus with possible values of InService and Shutdown.

This parameter is updated during the flowsheet update after optimization
completes. If the optimization decides the boiler equipment is off and hence
the flows through this equipment are zero, the parameter will be assigned as
Shutdown. As a result, the related equipment design equations are excluded
from the model and related variables are changed to Fixed to keep the model
Square.
This process during the flowsheet update can only work when the default
variable specifications do not change except the
SteamOut(“VHPSteam”).F.
DF_Boiler
Description
This model is an extension of the boiler model as it allows two fuel feeds.
Inlet Ports
FuelIn(“Fuel1”) Inlet Fuel No
FuelIn(“Fuel2”) Inlet Fuel No
Outlet Ports

Specifications
FuelIn(“FuelIn1”).F Heat flow of the first fuel. This can be
interchanged with the flow of the second fuel.
EffMethod Efficiency method. The default is Constant. The
options are Constant or LookUpTable.
FanCoeffB Coefficients for calculating the boiler fan power
FanCoeffC Coefficients for calculating the boiler fan power
If LookUpTable is selected as the efficiency method, then you must enter the
efficiency curve in the EffTable form. A minimum of two points (NeffPoints)
must be specified. The curve is in the form efficiency against steam flow.
Optimization Limits
If an efficiency curve is used then the optimization limits for the
minimum/maximum steam flow are defined as the range of the efficiency
curve.
Note: As two types of fuel can be used in the dual fuel boiler, one of them
must be specified as Fixed and another must be Free. In order to have
flowsheet updated successfully after the optimization, parameter
BalancingFuel must be specified as the correct fuel stream that are free to
change. Otherwise the flowsheet update will make flowsheet non-square.
Combustor

Description
This model is used to combust fuel in an air stream and so raises the
temperature of the air stream.
Inlet Ports
Outlet Ports
Specifications
FuelIn(“FuelIn1”).F Heat flow of the fuel used in the combustor.
Optimization Limits
O2min Minimum O2 in the exhaust.
Gas Turbine
Description
This is a simplified gas turbine model using performance curves. The model
uses lookup tables relating the heat consumption, exhaust flow, and
exhaust temperature to power production. Heat losses are a result of the
model calculations.

Inlet Ports
SteamIn(“SteamIn1”) Inlet Steam No
Outlet Ports
PowerOut(“PowerOut1”) Generated Power No
Specifications
Npoints The number of points that are available on the
performance curves. This can be entered on the
FlowTable or HeatTable forms.
Pow_Vals(n) The power values against which the
performance curves are entered. Theses are
entered on the Pow_Vals form.
HeatVals(n) The fuel demand at the various loads on the
HeatTable.
FlowVals(n) The exhaust flow at the various loads on the
FlowTable.
TempVals(n) The temperature of the exhaust gas on the
TempTable.
PowerOut(“PowerOut1”).Power The power generated by the gas turbine.
ApplyTemperatureCorrection Binary variable used to choose to apply
temperature correction.
K1Power Temperature correction factor for power
production (to be specified if temperature
correction is to be used).
K2Power Temperature correction factor for power
production (to be specified if temperature
K1HeatCons Temperature correction factor for fuel
consumption (to be specified if temperature
K2HeatCons Temperature correction factor for fuel
consumption (to be specified if temperature
K1Exhaust Temperature correction factor for Exhaust flow
(to be specified if temperature correction is to
be used).
K2Exhaust Temperature correction factor for Exhaust flow
(to be specified if temperature correction is to
be used).

K1ExhaustTemp Temperature correction factor for Exhaust
temperature (to be specified if temperature
K2ExhaustTemp Temperature correction factor for Exhaust
temperature (to be specified if temperature
Tref Reference temperature to be used in
temperature correction factors.
ApplyHumidityCorrection Binary variable used to choose to apply
humidity correction.
K1Humidity Humidity correction factor for power production
(to be specified if humidity correction is to be
used).
K2Humidity Humidity correction factor for power production
(to be specified if humidity correction is to be
used).
AugmentationFactor Power produced per unit of steam injection.
SteamInjectionPercent Steam flow as percentage of inlet air.
Optimization Limits
All limits for the optimization are determined from the performance curves.
Gas Turbine Model Input Forms
The gas turbine model requires relatively complicated input compared to
other process models in Aspen Utilities Planner model library and a custom
input form has been created to ease this task.
Access to Model Input Forms.
The gas turbine model input form is displayed by right clicking on the gas
turbine model on the flowsheet and then choosing Form |
PerformanceCorrectionInput from the context menu.

The input parameters are self-explanatory and consistent with the terms used
in the Specifications table earlier in the previous section.
Specify Humidity and temperature factors
To specify humidity and temperature correction factors, change the value of
ApplyTemperatureCorrection and ApplyHumidityCorrection into True.
New items will appear automatically, and you can input values as required.

The humidity correction coefficients are at the bottom of the form. The
humidity correction is calculated from these according to:
HumidityCorrection = Humidity*k1 + k2
Input Performance Curves
You can enter three performance curves for the gas turbine:
 Exhaust flow vs. Power.
 Exhaust temperature vs. Power.
 Heat consumption vs. Power.
To specify gas turbine performance curves, right click on the gas turbine and
choose from the Form menu item in the context menu.
Flow Curve
To open the flow curve, right click on the gas turbine and choose Form |
FlowCurve. FlowCurve Profile Plot appears.

Double click on any part of the diagram (the curve, coordinate, etc.) You can
change the text font, line color, point mark, etc. as you like.
If you want to edit the value of each point or enter additional points, right
click on the gas turbine and choose Form | FlowTable to open the
FlowTable table.
You can edit the value of existing points by changing the Value column.
Change the NPoints to add new points or delete existing points. After entering
the value, the new point will be shown in FlowCurve.

Heat Curve
To open the heat curve, right click on the gas turbine and choose Form |
HearCurve. HeatCurve Profile Plot appears.
click on the gas turbine and choose Form | HeatTable to open the
HeatTable table.

the value, the new point will be shown in HeatCurve.
Temp Curve
To open the temp curve, right click on the gas turbine and choose Form |
TempCurve. TempCurve Profile Plot appears.
click the mouse on the gas turbine and choose Form | TempTable to open
the TempTable table.

the value, the new point will be shown in TempCurve.
HRSG
Description
This is a simplified model of a heat recovery steam generator. A rigorous heat
and material balance is calculated. The inlets to the model are a steam
stream for the boiler feed water, air stream and fuel stream for
supplementary firing. The outlets of the model are two steam streams, one
for boiler blowdown and one for steam, and an air stream for flue gas.
The efficiency is specified as the maximum efficiency in the HRSG.

Inlet Ports
FuelIn(“Fuel”) Inlet Fuel No
Outlet Ports
Specifications
FuelIn(“Fuel”).F Heat flow of the first fuel. This can be interchanged
with the flow of the second fuel.
Tref The reference temperature against which efficiency is
defined, i.e. stack temperature at which the efficiency
of the boiler would be 100%.
MaxEff Maximum efficiency.
Optimization Limits
Note: There is a state parameter defined in the model called
OperationalStatus with possible values of InService and Shutdown.
This parameter is updated during the flowsheet update after optimization
completes. If the optimization decides the HRSG equipment is off and hence
the flows through this equipment are zero, the parameter will be assigned as
Shutdown. As a result, the related equipment design equations are excluded
from the model and related variables are changed to Fixed to keep the model
Square.

This process during the flowsheet update can only work when the default
variable specifications do not change except the SteamOut(“VHPSteam”).F.
FuelMixer
Description
This model is used to mix fuel streams.
Inlet Ports
FuelIn(“FuelIn1”) Inlet fuel stream Yes
Outlet Ports
FuelOut(“FuelOut1”) Outlet fuel stream no
Specifications
No specifications need to be defined in this model.
Optimization Limits
MinFuelDuty Minimum inlet fuel flow
MaxFuelDuty Maximum inlet fuel flow
FuelSwitch1toN

Description
This model is used to route a fuel stream to an outlet port.
Inlet Ports
FuelIn(“FuelIn1”) Inlet fuel port No
Outlet Ports
FuelOut(“FuelOutX”) Outlet fuel ports. X
represents the number
of the outlet port.
No
Specifications
nFuelOut Number of outlet fuel streams
Optimization Limits
MinimumFuelInletFlow/MaximumFuelInletFlow Minimum/Maximum flow on the
inlet fuel.
MinimumFlow(“FuelOutX”)/MaximumFlow(“Fuel
OutX”)
Minimum/Maximum flow on the
outlet fuel port X.
nMinOutlets/nMaxOutlets Minimum/Maximum number of
active outlet ports.
Emissions
Burner
Description
The Burner model is used to do the following tasks:
 Using multiple fuels, create emission flows based on “standard” flue-gas
generation (m3/tonne fuel fired).

Note: The theoretical flue-gas flow is calculated based on factors.
Different factors are available for gas fuels and liquid fuels. These factors
have to be converted in the same units of measure used for the
AirFlowFactors in the burner models.
 Model an individual burner, a group of burners, or a duel fuel burner, and
then build the necessary constraints.
 Calculate the flue-gas flow and composition. A butner block does not carry
out the thermal calculation. The fuel out of the burner block should be
connected to the fuel block where it is consumed.
Inlet Ports
SteamIn(“SteamIn1”) Inlet steam No
FuelIn(“FuelInX”) Inlet fuel – X
of inlet fuel ports
specified by variable
nFuelIn.
Yes
Outlet Ports
FuelOut(“FuelOutX”) Outlet fuel ports. X
of the outlet port.
No
AirOut(“AirOut1”) Outlet air No

Specifications
nBurners Define the number of burners that
exist
nBurnerGroups Define the number of groups in
which these burners are placed
nBurnerFuels Specify the number of burners in
which each fuel is used
BurnerFuel Specify the actual burners in
which the fuel is used
BurnersInGroup Specify the burners that form part
of each burner group
AtomisationSteamFactor(“FuelInletX”) Atomidation steam required per kg
fuel. X represents the number of
the inlet fuel
FuelInletToOutlet(“FuelOutletX”) Mapping inlet fuel to outlet fuel
port. X represents the number of
outlet fuel.
AirOut(“AirOut1”).T Outlet flue gas temperature
AirDensity Flue gas density
AirFlowFactor(“FuelInX”) Theoretical mass flow (tonner/hr)
of flue gas generation per GJ of
fuel. X represents the number of
inlet fuels
AirOut(“AirOut1).O2 Oxygen mass concentration of flue
gas stream.
Optimization Limits
nMinBurners/nMaxBurners Minimum/Maximum limits on the
total number of burners that can
be active at a time
nMinGroupBurners/nMaxGroupBurners Minimum/Maximum limits on the
total number of burners that can
be active in the given burner
group at a time
BurnersInGroup Specify the burners that form part
of each burner group

EmissionsChimney
Description
This model is used to combine multiple air/emission streams into a single
stream.
Inlet Ports
AirIn(“AirIn1”) Inlet air streams Yes
Outlet Ports
AirOut(“AirOut1”) Outlet air streams. No
Specifications
No specifications need to be defined in the model.
Optimization Limits
MinFlow Minimum total air flow in the
mixer
MaxFlow Maximum total air flow in the
mixer
EmissionsNode

Description
This model is used to add constraints on the emission discharges and
concentrations.
Inlet Ports
AirIn(“AirIn1”) Inlet air stream No
Outlet Ports
AirOut(“AirOut1”) Outlet air stream No
Specifications
The following equations are added in order to model and constrain the overall
SOX and CO2 emission in the tracking period:
 TotalSOX = PastSOXProd + RemainingTime * SOXFlow
 TotalCO2 = PastCO2Prod + RemainingTime * CO2Flow
 EndOfPeriodCO2conc = TotalCO2 / TotalFlueVol
 EndOfPeriodSOXconc = TotalSOX / TotalFlueVol
PastSOXProd Previous SOX production, kg
PastCO2Prod Previous CO2 production, kg
RemainingTime Time span of the current
optimization period, hr
Optimization Limits
MinAirFlow/MaxAirFlow Minimum/Maximum total air flow
from the block
MinSOXFlow/MaxSOXFlow Minimum/Maximum SOX flow in
the current optimization period
MinCO2Flow/MaxCO2Flow Minimum/Maximum CO2 flow in
the current optimization period
MinSOXConc/MaxSOXConc Minimum/Maximum SOX
concentration
MinCO2Conc/MaxCO2Conc Minimum/Maximum CO2
concentration
MinEndOfPeriodSOX/MaxEndOfPeriodSOX Minimum/Maximum SOX flow at
the end of tracking period
MinEndOfPeriodCO2/MaxEndOfPeriodCO2 Minimum/Maximum CO2 flow at
the end of tracking period
MinEndOfPeriodSOXConc/MaxEndOfPeriodSOX
Conc
Minimum/Maximum SOX
concentration at the end of
tracking period

MinEndOfPeriodCO2Conc/MaxEndOfPeriodCO2
Conc
Minimum/Maximum CO2
concentration at the end of
tacking period
MinTotalFlueGas/MaxTotalFlueGas Minimum/Maximum volumetric
flow of flue gas
EmissionsSwitch
Description
This model is used to route an emission stream to an outlet subject to the
SOX and CO2 flow and concentration limits specified for the ports.
Inlet Ports
AirIn(“AirIn1”) Inlet air No
Outlet Ports
AirOut(“AirOutX”) Outlet air, X represents
the number of outlet
air ports
No
Specifications
nAirOut Specify the number of outlet air
ports
Optimization Limits
MinInletAirFlow/MaxInletAirFlow Minimum/Maximum inlet air flow
MinAirFlowOut(“AirOutX”)/MaxAirFlowOut(“Air
OutX”)
Minimum/Maximum outlet air flow
on the outlet port X
MinSOXInletFlow/MaxSOXInletFlow Minimum/Maximum inlet SOX flow
MinSOXInletConc/MaxSOXInletConc Minimum/Maximum inlet SOX
concentration
MinCO2InletFlow/MaxCO2InletFlow Minimum/Maximum inlet CO2 flow

MinCO2Conc/MaxCO2Conc Minimum/Maximum inlet CO2
concentration
MinSOXOutConc(‘AirOutX”)/MaxSOXOutConc(“
AirOutX”)
Minimum/Maximum outlet SOX
concentration on outlet air port X
MinCO2OutConc(“AirOutX”)/MaxCO2OutConc(“
AirOutX”)
Minimum/Maximum outlet CO2
concentration on outlet air port X
NOXEstimator
Description
NOXEstimator is used as a general block to model NOX generation processes
such as Boiler, HRSG, Gas Turbine, etc. The model is typically used to handle
nonlinear NOX generation curve by piecewise linearization.
Inlet Ports
AirIn(“AirIn1”) Air inlet port Yes
SteamIn(“SteamIn1”) Steam inlet port Yes
FuelIn(“FuelIn1”) Fuel inlet port Yes
PowerIn(“PowerIn1”) Power inlet port Yes
WaterIn(“WaterIn1”) Water inlet port Yes
Outlet Ports
AirOut(“AirOut1”) Air outlet port No
SteamOut(“SteamOut1”) Steam outlet port No
FuelOut(“FuelOut1”) Fuel outlet port No
PowerOut(“PowerOut1”) Power outlet port No
WaterOut(“WaterOut1”) Water outlet port No

Specifications
nAirIn Number of air inlet ports
nSteamIn Number of steam inlet ports
nPowerIn Number of power inlet ports
nFuelIn Number of fuel inlet ports
nWaterIn Number of water inlet ports
nAirOut Number of air outlet ports
nSteamOut Number of steam outlet ports
nPowerOut Number of power outlet ports
nFuelOut Number of fuel outlet ports
nWaterOut Number of water outlet ports
nPoints Number of points in the NOX
generation
NOXCorrVars Boolean indicator of additional
correction variables on the NOX
generation
nNOXCorrVars Number of correction variables
NOXCorrectionVariables(*) The port name related to the
correction variables
NOXGenCorr_A(*) Parameter A in the correction for
the corresponding correction
variable
NOXGenCorr_B(*) Parameter B in the correction for
the corresponding correction
variable
Notes:
 The above parameters for specifying the number of inlet and outlet ports
have a maximum limit of 1 and minimum limit of 0. This indicates these
parameters behave more like Boolean indicators of whether the block has
the particular type of ports (1 = Yes, 0 = No).
 In the Emissions table, you must specify nPoints and then enter the NOX
generation curve in terms of Fuel consumption vs. NOX generation.
 If the NOX generation curve also involves other variables, they can be
included by specifying the correction variables. For example, if the NOX
generation curve can be expressed as an nonlinear function of fuel
NOXCorrectionVariables(1) should be SteamOut1.
NOX = f (Fuel) + A*Steam + B
 This block is typically inserted in front of a fuel consumption block such as
Boiler, GT, HRSG, etc. The inlet fuel is first fed to the NOX Estimator and
then passes through to the fuel consumption block. In the NOXEstimator
block, at least an inlet fuel port and an outlet air port must be specified.
Other ports can be added depending on the correction terms.
 NOXGen, NOXGen_Fuel and NOXGen_TotalCorr are the variables that
store the results of NOX generated in the progress.

Optimization Limits
There are no optimization limits for this model.
Templates
General Model
Description
This is a general model, which has all the types of ports at the inlet and at the
outlet. You can specify the number of ports for each type in the Summary
form.
Inlet Ports
SteamIn(“SteamInn”) Steams Port 1 to n Yes
AirIn(“AirInn”) Air Ports 1 to n Yes
FuelIn(“FuelInn”) Fuel Ports 1 to n Yes
PowerIn(“PowerInn”) Power Ports 1 to n Yes
WaterIn(“WaterInn”) Water Ports 1 to n Yes

Outlet Ports
SteamOut(“SteamOutn”) Steams Port 1 to n No
AirOut(“AirOutn”) Air Ports 1 to n No
FuelOut(“FuelOutn”) Fuel Ports 1 to n No
PowerOut(“PowerOutn”) Power Ports 1 to n No
WaterOut(“WaterOutn”) Water Ports 1 to n No
Specifications
SteamOut(“SteamOutn”).F Steam Mass Flow
SteamOut(“SteamOutn”).T Steam Temperature
SteamOut(“SteamOutn”).P Steam Pressure
FuelOut(“FuelOutn”).F Fuel Heat Flow
FuelOut(“FuelOutn”).OD Fuel Oxygen Demand
FuelOut(“FuelOutn”).CV Fuel Calorific Value
FuelOut(“FuelOutn”).MW Fuel Molecular Weight
WaterOut(“WaterOutn”).F Water Mass Flow
WaterOut(“WaterOutn”).T Water Temperature
WaterOut(“WaterOutn”).P Water Pressure
AirOut(“AirOutn”).F Air Mass Flow
AirOut(“AirOutn”).O2 Air O2 Content
AirOut(“AirOutn”).SOx Air SOx Content
AirOut(“AirOutn”).T Air Temperature
AirOut(“AirOutn”).CO2 Air CO2 Content
PowerOut(“PowerOutn”).Power Power Flow
SteamIn(“SteamInn”).F Steam Mass Flow
FuelIn(“FuelInn”).F Fuel Heat Flow
WaterIn(“WaterInn”).F Water Mass Flow
AirIn(“AirInn”).F Air Mass Flow
PowerIn(“PowerInn”).Power Power Flow
In all cases n refers to the port number.
Optimization Limits
There are no optimization limits for this model.

Flowsheet Development
Dealing with Snapshots
A Snapshot is a binary data file that stores all the variable values in the
simulation. The snapshot files are generated by Aspen Utilities Planner/Aspen
Custom Modeler according to the snapshot settings in Tools | Settings.
Please refer to the Aspen Custom Modeler User Guide to learn more about
snapshots (search for Snapshot).
Variable Specification – Fixed and Free
Since Aspen Utilities Planner is derived from Aspen Custom Modeler, all
utilities models are written in the Equation Oriented (EO) form. All variables
declared in models have three specifications by default: Fixed, Free, and
Initial. The Initial specification is used by dynamic simulation and ignored in
When a variable is specified as Fixed, it is an input value, and the value will
not be changed during the simulation. If a variable is declared as Free, it is an
output variable, and its value will be determined by the equation calculations.
The value is updated when the simulation or optimization is complete.
All equations are solved simultaneously in the static-state EO model by an
algebraic algorithm (e.g., Newton-Raphason method). In order to solve the
model, the flowsheet must be square, i.e., the number of equations defined
in the model must be equal to the number of Free variables.
To learn more about variable specification, please refer to the Aspen Custom
Modeler User Guide.

Appendix 1 – Configuring the
Demand Forecasting Editor
The demand forecasting application uses a subset of tables within the demand
database which need to be configured following a certain convention. The
structure and relationships between these tables is shown in the diagram
below:
Structure of the Demand Forecasting Module
The demand forecasting application calculates a number of utility demands
(known as DemandCalcs or DemandVars within the database) from general
equations that contain production parameters and operation modes. These
DemandCalcs are linked to appropriate block ports within the Aspen Utilities
Flowsheet via a mapping in the Profiles Database.
Appendix 1 – Configuring the Demand Forecasting Editor 181

In earlier versions the equations were of the form:
y = f(x)
where:
y = the utility demand
x = production parameter
and five equation functions were supported:
 Fixed (y = A)
 Linear (y = Bx+A)
 Quadratic (y = Cx2+Bx+A)
 Power (y=DxE)
 Exponential (y=GeFx)
You selected the equation type and entered the equation coefficients.
The new equations are much more general and flexible. Because DFE uses
Microsoft Excel to evaluate the equations, the equations can contain any
operation that can be used in Excel.
This version of the Demand Forecasting is configured slightly differently than
11.1 to support the use of multiple cases within the profiles editor. It will
however read databases configured for the 11.1 editor.
To distinguish between various configurations of Demand Database there is a
version field in the VersionInfo table of the Demand Database.
The possible values are:
 1.0.0.1 – Describes an 11.1 database without any support for modes.
 2.0.0.1 – Describes an 11.1 database with support for modes.
 2.0.0.2 – Describes a database configured to be compatible with multiple
Cases.
The following steps are required to configure the Demand Forecasting
module.
1 Configuring the demand profile and period set ID the data is saved to.
This is achieved by configuring the data within the following tables:
o PeriodSet
o Period
o GeneralInput
o Config
2 Configuring the data about the production parameters. This is achieved by
configuring the following tables:
o DemandForecastingInput
o XinVal
182 Appendix 1 – Configuring the Demand Forecasting Editor

3 Configuring the various modes of operation for each unit – if applicable.
This is achieved by configuring the following tables:
o TblModeValues
o TblModes
o PeriodModes
4 Configuring the individual equations that make up the CalcVars. This is
achieved by configuring the CalcVars table.
5 Configuring the link between CalcVars and the variables within the Aspen
Utilities Model. This is achieved by configuring the DemandCalcs table.
Before you Start
The easiest way of configuring the demand forecasting application is to
configure each table in turn in the order shown above. Before starting to
configure the demand database the demand profiles within the profiles
database should already have been configured using the Profile data editor.
We will use the example file that comes with the Aspen Utilities Planner
Installation (example.auf) to show how to configure Demand Forecasting.
Note: This example does not refer to the example databases in the Aspen
Utilities installation.
Example Aspen Utilities Flowsheet
Demands need to be calculated for five demand blocks:
 SteamFeed

 HPUSE
 LPGEN
 LPUSE
 PWRUSE
There are three process units on the site (Acetic Acid, VAM and EtAc) each of
which takes a different mix of utilities. The individual utility demands for each
of the process units need to be calculated, summed and linked to the correct
demand block.
The table below shows which unit uses/generates which utility and the
equation that links the utility demand to the production parameter. All of the
production rates are in ton/hr.
Unit Process Equation
HP Generation
Acetic Acid Process Mode 1:
(ton/hr)
0.4* Acetic Acid production rate + 2
Mode 2:
2.3 * Acetic Acid production rate
VAM Process 1.2* HP Use VAM production rate + 1
(ton/hr) EtAc Process 0.03* (EtAc production rate)2 +0.4*
EtAc production rate
LP Generation
(ton/hr)
EtAc Process 1.7* EtAc production rate + 3.8
Acetic Acid Process Mode 1:
1.02* Acetic Acid production rate
Mode 2:
23
LP Use
(ton/hr)
VAM Process 3e(VAM production rate*0.06)
Acetic Acid Process 9.5
VAM Process 3.2
Power Use
(MWh)
EtAc Process 0.27* EtAc production rate
Demand Forecasting Correlations
The equation coefficients should be such that the y value is calculated in the
Aspen Utilities Planner base units of measurement.
Units of measurement for the x parameter can be chosen. When the demand
forecasting application is also used for performance monitoring, the equations
should be set up so that the x parameter is in the same units of measure as
any corresponding IMS tag which measures that parameter.

The Profiles database should already have been generated and the Demand
Variable Map is shown below:
ID DemandProfileId EquipmentPropId IP21SourceTag
HPUSE.D1 D1 HPUSE.SteamIn1
LPGEN.D1 D1 LPGEN.SteamOut11
LPUSE.D1 D1 LPUSE.SteamIn1
PWRUSE.D1 D1 PWRUSE.PowerIn1
SteamFeed.D1 D1 SteamFeed.SteamOut
1
Configured tblDemandVarMap
Units of Measure
All utility demands should be calculated in the Aspen Utilities Planner base
units of measure.
These are:
 For steam/water flows ton/hr.
 For power flows MW.
 For fuel flows GJ/hr.
 For air flows, ton/hr.
The units of measure for each of the production parameters needs to be
consistent within Demand forecasting, for example all correlations which use
VAM production rate need to have the VAM production rate in the same units
of measure. However, the units of measure for production parameters can be
mixed, e.g., VAM production rate can be entered in ton/hr and EtAc
production rate can be entered in kg/hr.
If Demand forecasting is used on-line for utility target calculations, the unit of
measure for each of the production parameters should be the same as the
unit of measure for that parameter within the IMS.
Configuring General
Information
EquationTypes
This table lists all of the equation types that are used within Demand
forecasting.
Important: Do not edit this table.

Operators
This table lists the operators used within the demand forecasting module.
Important: Do not edit this table.
Config
This table is used to set the number of decimal places that are used to display
the results of the calculation.
PeriodSet
There are three fields for each record:
Field Description
PeriodSetID This is the ID of the period set that the data is saved to. The
period set ID must be the same as the period set ID used to define
the default case within the profiles database. This is usually P1.
NoOfPeriods This is the number of periods within the profile. When setting up
the database this can be entered as 1 and then can be increased
when the data base configuration is complete and the editor can
be used.
StartTime This is the starting time for the first period. Again any date/time
can be entered here as it can be altered using the editor. The
format for the data/time is dd/mm/yyyy hh:mm:ss.
PeriodSetID NoOfPeriods StartTime
P1 1 07/05/2002 00:00:01
Completed PeriodSet Table
Note: If your database has a version number of 2.0.0.2, the PeriodSetID field
is not used to determine the periodset written to in the profiles database,
instead the PeriodSetID as defined by the Case (from tblCases in the Profiles
Database) is used.
Period
There are four fields in the Period table:
Field Description
PeriodID A unique ID for the period, used when specifying the values of the
production parameters. When periods are added to the demand
forecasting database, the PeriodIDs are generated automatically
and are of the form Period1, Period2 etc. It is therefore
recommended but not necessary to use Period1 as the ID for the
first period.
PeriodNo This is the order number of the period, i.e., period 1 has the
PeriodNo 1, period 2 has the PeriodNo 2 and so on.

Field Description
PeriodLength This is the length of the period in hours. Any number can be
entered here as it can be changed within the editor.
PeriodSetID This is the period set that has been set in the PeriodSet Table.
PeriodID PeriodNo PeriodLength PeriodSetID
Period1 1 1 P1
Completed Period Table
GeneralInput
There are three fields in the GeneralInput table:
Field Description
DemandProfileID The ID of the demand profile the data is saved to. In the first
instance you cannot change the profile the data is saved as
because the profiles editor does not support multiple profiles.
The ID selected must be the same ID and the default demand
profile ID used in the profiles database. This is usually D1.
PeriodSetID This is the ID of the period set the period data is saved to. As
with the demand profile ID, you cannot change this
information and the selected ID must be the same as the
default period set ID used in the profiles database. This is
usually P1.
DefaultCase This field is not used.
For our example the completed table looks like this:
DemandProfileID PeriodSetID DefaultCase
D1 PS1 1
Completed GeneralInput Table
Note: If your database has a version number of 2.0.0.2 then the
DemandProfileID field and PeriodSetID field are not used. These values are
taken from the Current case (and are defined in tblCases of the Profiles
Database).
Configuring Production
Parameters
DemandForecasting
Input
This table is used to list all of the production parameters used in demand
forecasting equations:

Field Description
ID A short ID for the production parameter used internally within the
database. It should be descriptive enough for you to configure the
database but not too long. For example, one of our production
parameters is VAM production so the ID could be VAMProd.
Legend The legend for the production parameter. This legend is displayed
within the editor and therefore should provide sufficient
information to the reader. It is also useful to include the unit of
measure for the production parameter. For our example, the
legend could be VAM Production Rate, ton/hr
TagID This field is not used.
DefaultXVal The default value for the production parameter used if the number
of periods used for demand generation is increased. These data
can be altered using the editor.
In our example, we have the following production parameters:
 Acetic Acid Production Rate
 VAM Production Rate
 EtAc Production Rate
All of these production rates are in ton/hr.
For our example, the completed table is as follows:
ID Legend TagID DefaultXVal
AAProd Acetic Acid Production Rate,
ton/hr
25
VAMProd VAM Production Rate, ton/hr 31
EtAcProd EtAc Production Rate, ton/hr 27
Completed DemandForecastingInput Table

XinVal
This table is used to specify the value of the production parameters. Some
data needs to be entered into the table initially but this data can then be
edited using the editor:
Field Description
ID A unique ID consisting of a concatenation of the
DemandForecastingID and the Period Number. This must
be typed into the database initially but is automatically
generated when further periods are added to the demand
forecast.
DFID The DemandForecastingID for the production parameter
and is selected from a drop-down box
DemandProfileID The demand profile ID associated with the values. This is
selected from the drop-down box
PeriodID The period that the production parameter is being set for.
This is always likely to be period 1 as it is unlikely the
database would initially be set up for more than one
period.
X This is the value for the particular production parameter
for the particular period.
ID DFID DemandProfileID PeriodID X
AAProd.1 AAProd D1 Period1 23
EtAcProd.1 EtAcProd D1 Period1 28
VAMProd.1 VAMProd D1 Period1 30
Completed XinVal Table

Configuring Modes
TblModes
This table is used to provide information on which plants have modes. The
table consists of the following fields:
Field Description
Mode_ID This ID is used to link the mode to the Plant.
Legend The legend viewed through the demand forecasting editor.
Description This field provides a more detailed description. This is not viewed
through the editor.
DefaultValue The default mode used if additional periods are added to the
profile. This is used to initialize the program and the value can be
changed.
Mode_ID Legend Description DefaultValue
ACETIC Acetic Acid Plant
Mode
Correlation adjuster for
Acetic values
ACETIC.LEAN
EO EO Mode Correlation Adjuster for
EO values
EO.MEDIUM
SEASON Season Seasonal adjuster for
correlations
SEASON.WINTER
Completed tblModes Table

TblModeValues
This table is used to list all of the available modes for each of the process
units. The table consists of the following fields:
Field Description
ID A unique ID for each mode the plant can operate it. The
convention is to concatenate the Mode_ID with the mode ordinal
value.
Mode_ID The Mode_ID as described in the previous table.
ValueString Description of the mode.
OrdinalValue An integer value for the mode. This must be unique within a
Mode_ID.
ID Mode_ID ValueString OrdinalValue
ACETIC.LEAN ACETIC Lean 1
ACETIC.RICH ACETIC Rich 2
EO.HIGH EO High 1
EO.LOW EO Low 3
EO.MEDIUM EO Medium 2
SEASON.FALL SEASON Fall 4
SEASON.SPRING SEASON Spring 2
SEASON.SUMMER SEASON Summer 3
SEASON.WINTER SEASON Winter 1
Completed tblModeValues Table
PeriodModes
This table is used to store the mode setting for each period in the profile. The
table consists of the following fields:
Field Description
PeriodMode_ID A concatenation of PeriodID and Mode_ID to make a unique
identifier.
Period_ID The ID of the period in question.
Mode_ID The Mode_ID as described in the previous table.
ModeValueID ID (from tblModeValues) of the mode to be used in that period.
PeriodMode_ID Period_ID Mode_ID ModeValueID
Period1.ACETIC Period1 ACETIC ACETIC.LEAN
Period1.SEASON Period1 SEASON SEASON.FALL
Completed PeriodModes Table

Configuring Calculations
Refer to the CalcVars section if you need to reference earlier versions of the
Demand database.
tblEquationDefinition
This table specifies the equations used for calculating the utility demands
from production parameters and modes of operation.
The table consists of the following fields:
Field Description
recID An ID created automatically by Microsoft Access.
EqnID The equation ID referenced by DemandVarEquationID in the
DemandCalcsEquations table
EqnDescription A description of the utility demand being calculated by the
equation. The description is displayed in Equation Editor.
EqnString Description of each equation.
In our example, if the production rate is zero, the utility demands should be
zero also. Therefore we need to put a conditional (IF statement) around the
equation.
The completed table might be:
recID EqnID EqnDescription EqnString
1 cvY1 Reboiler Steam IF("[SEASON]"="(SEASON.WINTER)",
IF([X1]>0,6+0.2*[X1]+2*[X1]^2,0),90)
2 cvY10 CT2 Turbines Y10 IF("[EO]"="(EO.MEDIUM)",5,0)
3 cvY11 CT2 Turbines Y11 IF("[EO]"="(EO.LOW)",0,0)
4 cvY12 CT2 Turbines Y1 IF("[SEASON]"="(SEASON.FALL)",1,0)
5 cvY13 CT2 Turbines Y13 IF("[SEASON]"="(SEASON.SUMMER)",3,0
)
6 cvY14 CT2 Turbines Y14 IF("[SEASON]"="(SEASON.WINTER)",4,0)
7
cvY2 Stripping Steam IF("[ACETIC]"="(ACETIC.LEAN)",0,0)
8 cvY3 Turbine PT5 0
9 cvY4 CT1 Turbines 15
10 cvY5 CT2 Turbines Y5 0.5*[X1]^1.5 + 37.71
11 cvY6 CT2 Turbines Y6 IF("[ACETIC]"="(ACETIC.RICH)",1000,0)
12 cvY7 CT2 Turbines Y7 IF("[SEASON]"="(SEASON.SPRING)",2,0)
13 cvY8 CT2 Turbines Y8 IF("[EO]"="(EO.HIGH)",10,0)
14 cvY9 CT2 Turbines Y9 IF("[ACETIC]"="(ACETIC.LEAN)",0.5,0)
15 HPUSE.St
eamIn1
Total
HPUSE.SteamIn1
+[cvY1] +[cvY2]
16 LPGEN.St
eamOut1
Total
LPGEN.SteamOut
1
+[cvY4] +[cvY3]

CalcVars
This CalcVars section, while obsolete, is included in case you need to
reference earlier versions of the Demand database. Refer to the
tblEquationDefinition section for a description of the current database.
This table specifies the equations used for calculating the utility demands
from the production parameters.
Field Description
DemandForecastingInputID The ID of the production parameter used to
calculate the utility demand. This ID is selected
from a drop-down box.
YvalID This field is not used.
CalcVarID A short but descriptive ID for the utility demand
that is being calculated. This ID must be unique.
In our example, we calculate the HP use on the
EtAc plant. Therefore the CalcVarID could be
EtAcHPUse.
Legend A longer description of the utility demand being
calculated. This is the description displayed.
Therefore for our example, the legend may be
EtAc HP Steam Use, ton/hr.
EquType The type of equation used to calculate the utility
demand. This is selected from a drop-down list.
TagID This field is not used.
CoeffA - CoeffG These are the coefficient for the demand
generation equation. Use the convention shown in
section A1.
IsZeroNotZero A flag used to ignore any fixed consumptions if the
production rate is zero, i.e., if an equation is of the
form 2 * production rate +3, if the production rate
is zero the equation still yields a demand of 3. If
the utility demand of the unit is zero when the unit
is shut down then this field should be ticked off.
Mode The particular mode for which this calculation is
applicable. This is the ID from tblModeValues. If
there are no modes then the value NONE.ALL
should be entered.
ModeID This is the mode_ID from tblModes.
In our example, if the production rate is zero, the utility demands should be
zero as well. Therefore, the IsZeroNotZero flag must be set if there are any
fixed consumptions. Also the power usage correlations on Acetic Acid and
VAM are not a function of production rate but they need to be linked to
production rate to enable the flag to work.

For the example, the completed table is shown in the following table:
Completed CalcVars Table

Configuring Demand
Calculations
Refer to the DemandCalcs section if you need to reference earlier versions of
the Demand database.
DemandCalcsEquations
This table is used to relate a Demand variable to the equation that calculates
the demand.
The DemandVarID along with tblDemandVarMap in the Profiles database link
the total utility demand to a variable in the Aspen Utilities flowsheet.
Field Description
DemandVarID This field maps a demand to an Equipment Property in
the Profiles database to one equation in
tblEquationDefinition. The name of this field is a legacy
from 11.1.
This field should contain the EquipmentPropId defined for
the Demand in question from the tblDemandVarMap
table in the profiles database
DemandVarEquationID The ID of the equation that calculates the demand for
DemandVarID
DemandVarID DemandVarEquationID
HPUSE.SteamIn1 HPUSE.SteamIn1
LPGEN.SteamOut1 LPGEN.SteamOut1
PWRUSE.PowerIn1 PWRUSE.PowerIn1
SteamFeed.SteamOut1 SteamFeed.SteamOut1
Configured DemandCalcsEquations Table
DemandCalcs
This DemandCalcs section, while obsolete, is included in case you need to
reference earlier versions of the Demand database. Refer to the
DemandCalcsEquations section for a description of the current database.
This table is used to add all of the individual CalcVars together and link them
to a DemandVarID, which through the profiles database, links the total utility
demand to a variable in the Aspen Utilities flowsheet.
Field Description
DemandVarID This field maps a demand to an Equipment Property in the Profiles
database to one or more calculations the results of which are
combined to produce the overall demand. The name of this field is

Field Description
a legacy from 11.1.
This field should contain the EquipmentPropId defined for the
Demand in question from the tblDemandVarMap table in the
profiles database.
CalcVarID The calculated utility demand that is part of that particular overall
utility demand. This is selected from a drop-down box.
Operator An operator which shows the relationship of that particular utility
demand (CalcVar) to the overall demand (i.e., is added to the
overall demand or taken away).
In our example, we have a single block representing HP Use and the
DemandVarID defined for this in the Profiles database is HPUSE.D1.
Therefore, we enter the EquipmentPropId value for that record in the Profiles
database which is HPUSE.SteamIn1
However, two plants take HP steam: VAM and EtAc. The two demands must
be added together to give the total HP Demand. Therefore, in the table we
must add a record with the DemandVarID of HPUSE.SteamIn1, select the
CalcVar associated with HP Steam demand in VAM (VAMHPUse) and then
select the operator +, since this demand is being added to the overall
demand.
A second record is then added to the table, again with the DemandVarID of
HPUSE.SteamIn1 but this time select the CalcVar associated with HP Steam
use in EtAc (EtAcHPUse). Again, the operator to use is +.
Where there are specific calculations for modes all of the calculations should
be included (as shown for SteamFeed.SteamOut1) below. The executable
determines which equations should be ‘switched on’ depending upon the
particulate mode selected by the user.
DemandVarID CalcVarID Operator
SteamFeed.D1 AAHPGenMode1 +
SteamFeed.D1 AAHPGenMode2 +
LPUSE.D1 AALPUseMode1 +
LPUSE.D1 AALPUseMode2 +
PWRUSE.D1 AAPower +
HPUSE.D1 EtAcHPUse +
LPGEN.D1 EtAcLPGen +
PWRUSE.D1 EtAcPower +
HPUSE.D1 VAMHPUse +
LPUSE.D1 VAMLPUse +
PWRUSE.D1 VAMPower +
Configured DemandCalcs Table

Index
A
Adding data to the blocks 8
Aspen Utilities menu bar in
Microsoft Excel 94
Aspen Utilities models
creating 8
selecting 8
Aspen Utilities windows 5
AspenTech support 3
AspenTech Support Center 3
Availability profile 17
C
customer support 3
D
Demand
air 122
blocks 120
dual fuel 123
fuel 121
min. and max. flow limits 120
power 121
steam 120
Demand profile 13
documentation 2
E
e-bulletins 3
Emissions models
Burner 169
EmissionsChemney 172
EmissionsNode 173
EmissionsSwitch 174
NOXEstimator 175
Equipment constraints 111
Equipment filter 21
F
Feed blocks 116
Filter types
equipment 21
Fuel models
boiler 154
combustor 158
df_boiler 156
FuelMixer 168
FuelSwitch1toN 169
gas turbine 158
HRSG 166
H
Headers
air mix 126
fuel 125
power 126
steam 124, 151, 152, 153
Heat exchangers
airairexchanger 150
as_heatex 142
chiller 143
condenser 145
fuelvap 145
heater 146
heater_1 147
ww_heatex 148
help desk 3
Hot standby requirements 71
I
Initializing physical properties 6
Index 197

Installing the Microsoft Excel add-in
93
M
Microsoft Excel
add-in 93
Aspen Utilities menu bar 94
simulation links worksheet 96
Model
limits 111
lists 112
standard variable names 114
structure 113
Multi-period optimization 109
P
Port types 115
Profile types
availability 17
demand 13
Profiles data editor
accessing 14, 33
availability profile data 17
availabilty profile 17
demand profile 13
overview 12
using 13, 48
Pumps
drive list 134
pump 132
pump list 136
S
Section contents 2
Simulation mode 8
Starting a simulation 9
Starting Aspen Utilities 5
Startup/shutdown constraints 73
Steam models
deaerator 127
desuperheater 129
sim_valve 128
stm_flash 130
stm_mix 131
Stream types 115
support, technical 3
T
Tariff data editor
contract definition table 34
data required 35
editing the add contract dialog
36, 39
overview 32
using 32
technical support 3
Templates 177
Turbines
stm_turbine 137, 139
U
Utility supply blocks 116
V
Viewing results from Microsoft
Excel 93
W
web site, technical support 3
198 Index

Aspen utilities user guide v7 2

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Aspen utilities user guide v7 2