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Problem Statement: Is there a Property Set (Prop-Set) to calculate Octane Number (Motor and Research)? | Solution: If you have entered data for Assay Data Analysis (ADA) as a Property Curve on the Assay/Blend | Property Curve| Petro Properties sheet, you have four options for reporting Octane Number (as determined from a fit of the curve). They are:
Parameter
Description
MOC-NO
Motor octane number
MOCNCRV
Motor octane number curve
ROC-NO
Research octane number
ROCNCRV
Research octane number curve
To create a property set:
1. Navigate to the Properties Prop-Sets folder within the Data browser. Click the New... button and provide a unique name, i.e., OCTANE.
2. From the Physical properties drop-down list, choose the property you want to report. For easier searching, click on the Search button at the bottom of this form and type ?octane? to see your four options.
Keywords: Properties, Prop-Sets, octane
References: None |
Problem Statement: What is the reference temperature To in the power law expression for reaction kinetics? How should it be used? | Solution: A reference temperature (To) was added to the standard power law expression in Aspen Plus 10.0. In Aspen Plus 9, only the standard power law expression was available.
If To is entered in the power-law kinetic rate expression, the form of the equation is
rate of reaction = k (T/To)^n exp[ (-E/R) (1/T - 1/To) product sum (Ci^ai)
where
k = Pre-exponential factor
T = Absolute Temperature
To =
Keywords: Reaction, reaction kinetics, power-law, reference temperature, chemical reaction, reactions, powerlaw
References: Temperature
n = Temperature exponent
E = Activation energy
R = Gas law constant
Ci = Concentration of the ith component
ai = Exponent of the ith component
If To is left blank, the form of the equation is the standard power-law expression:
rate = k (T^n) exp[ (-E/RT) product sum Ci^ai
The reference temperature To in the reaction kinetic power law expression is just a parameter. The expression changes depending on whether To is entered. If the field is left blank, the expression changes to standard form of power-law and there is no To term. By default To is blank. Do not enter a standard temperature in this field if you want the standard power-law expression.
A reference temperature was added to make it easier to regress both the Pre-exponential factor and the Activation Energy at the same time. With the standard power law expression, the activation energy controls the magnitude of the reaction rate as well as the temperature sensitivity of the reaction rate. With the reference temperature term added, the pre-exponential factor controls the magnitude of the reaction rate at the reference temperature, and the activation energy controls the temperature sensitivity of the rate constant.
See the Aspen Plus User Guide or Help, Specifying Reactions and Chemistry for more information. |
Problem Statement: The online-help of Aspen Custom Modeler provides an example for the use of the Results.CopyValues method.
The command shown in the example has the same function as the Advanced Copy dialog available from the Snapshot Management dialog box. That means it requires the specification of a flowsheet object (e.g., a block ID), and a variable name.
How can one copy all variable values of the simulation at once? In other words, what is the automation equivalent to Tools | Snapshots... | Copy Values? | Solution: The required syntax to copy all variable values from a snapshot is:
Simulation.Results.CopyValues aResult, False, True, True, False, True, True, , ~
Keywords: Automation
Results
Snapshot
Copy
References: None |
Problem Statement: How do you select the Unit Of Measure and how do you add a new PhysicalQuantity? | Solution: For more information see the online documentation.
1 How do you select the Unit Of Measure (UOM)?
The user can change the UOM by selecting it using Tools\Units of Measurement and choosing the UOM from the built in list which consists of:
Metric
US
ENG
MET
SI
METCBAR
SI-CBAR
2 How do you add a new PhysicalQuantity?
The model must be written in the base units of measure, which is Metric.
The PhysicalQuantity property is declared in the new variable type.
The unit conversions are defined in OnNewDocumentScript.vb (located ..\AMSystem11.1\bin directory
The following example adds physical quantities for length, temperature and current with base units of measurement of meters, degrees Celsius and Amperes respectively.
bOK = UOM.AddPhysicalQuantity(Length, m ,17, 1)
bOK = UOM.AddPhysicalQuantity(Temperature, C, 22, 4)
bOK = UOM.AddPhysicalQuantity(Current, A)
Note: The syntax is:
bOK = UOM.AddPhysicalQuantity(PhysicalQuantityName, BaseUnitSymbol, AspenPlusQuantity, AspenPlusUnit)
Where:
Variable Name
Description
bOK & UOM
Previously defined Visual Basic® variables. Can be any name you choose.
PhysicalQuantityName
The name of the physical quantity
BaseUnitSymbol
The symbol for the base units of measurement for this physical quantity
AspenPlusQuantity
The integer number of the corresponding physical quantity in Aspen Plus® as entered in the Aspen Plus file rcunits.dat.
AspenPlusUnit
For the given Aspen Plus physical quantity this is the integer number of the Aspen Plus unit that matches the base units for the physical quantity.
The last two numbers can be omitted and they are not used unless the intention is to use the ACM model in Aspen Plus. Here is an excert from the rcunits.dat file for Temperature. Temperature is the 22 unit of measure in the list in this file and C is the fourth item in the list under Temperature (degrees Celcius is the base unit for Temperature).
22 05 TEMPERATURE TEMPERATURE TEMP
K 1.
F 0.55555556 255.37222
K 1.
C 1. 273.15
R 0.55555556
To define alternate units for PhysicalQuantity
bOK = UOM.DefineConversion (Current, mA, 1e-3, 0.0)
Note: The syntax is:
bOK = UOM.DefineConversion(PhysicalQuantityName, UomSymbol, Multiplier, Offset)
Where:
Variable Name
Description
bOK & UOM
Previously defined Visual Basic® variables. Can be any name you choose
PhysicalQuantityName
Name of a previously defined physical quantity
UomSymbol
The symbol of the UOM to which you are making the conversion from the base UOM
Multiplier
The factor by which you need to multiply the UOM value to convert to the base UOM value
Offset
The difference you need to make to the UOM value to convert to the base UOM value
Keywords:
References: None |
Problem Statement: While running a data regression, what do the messages about constraints not satisfied mean?
There are two possible messages:
1. *** CANNOT SATISFY CONSTRAINTS ***
2. *** DRS CONVERGED IN X ITERATIONS, BUT CONSTRAINTS ARE NOT TIGHTLY CONVERGED ***
What is the difference? | Solution: The two messages about Constraints meet different conditions. The Britt-Lueke algorithm calculates a penalty function which is proportional to the sum of constraints.
If the penalty is greater that 0.0001 times the sum of square errors (the objective function) then the message is
*** CANNOT SATISFY CONSTRAINTS ***
If the penalty is greater that 0.01 times the sum of square errors then the message is
*** DRS CONVERGED IN X ITERATIONS, BUT CONSTRAINTS ARE NOT TIGHTLY CONVERGED ***
There is no tolerance directly associated with this. If either message occurs then the user should check that:
1. All of the data is reasonable and does not contain outliers.
2. The best model is used (activity model, equation of state).
3. The number of parameters regressed is reasonable - not too few or too many.
The convergence tolerance can be decreased to try to reach a smaller sum of squares and the constraints (phase equilibrium and properties) may be satisfied.
Keywords: drs
regression
contraints
References: None |
Problem Statement: Simple RadFrac column with free-water fails to converge. The organic phase is not even present on most stages. Why does this occur? | Solution: The free-water approach requires that you always have an organic phase. This is not a bug, but rather a limitation of the theory behind the free water calculations. TheSolution under these circumstances is to do rigorous 3-phase vapor-liquid-liquid (VLL) equilibrium calculations. In 2004 and higher, using dirty water rather than free water would work as another option.
This problem arises because the vapor phase is assumed to be in equilibrium with the organic phase (the water phase only have 1 component and there is nothing to tie y(i,j) with x(i,j) when i <> water).
The free-water calculation tries to keep the ratio of the L1 phase to the total liquid (beta) to be at least 1e-15; however, in this case it really is still incorrect. In reality, when the non-water composition in the liquid phase falls below 1e-7, the algorithm for free-water is no longer robust enough and the user should consider VLL.
Keywords: VLLE
LLE
free water
tower
column
References: None |
Problem Statement: How can stream results be copied to input forms to be used as tear estimates? | Solution: Simulation results for a stream can be copied onto the its input form in Aspen Plus 10.1 and later to provide tear stream estimates. This process is called Reconcile a stream.
Stream reconciliation can be very strategic in flowsheets with recycle loops. Once the flowsheet has converged, the results for the tear stream can be copied to the tear stream's input form. Even if the flowsheet is re-initialized, the next simulation solves much quicker because excellent starting data has been provided for the tear stream via its stream input form. For intermediate and product streams, entries on the stream input form are used for providing starting estimates.
Streams that have not been reconciled will have Unreconciled in their status. There is nothing wrong with a stream being unreconciled. In fact, only tear streams should be reconciled to improve convergence time.
The easiest way to identify the tear streams is to look in the beginning of the Control Panel where the sequence and convergence
blocks information is displayed. The streams that are converged in the Convergence blocks such as WEGSTEIN (the default method) are the tear streams. There will be a message similar to the following: Block $OLVER02 (Method: WEGSTEIN) has been defined to converge streams: 3
The reconciled data stays the same even if there are
changes in the initial conditions (feed streams and block inputs). If the initial conditions are going to be varied drastically the reconciled stream data being used as an initial starting point could cause convergence problems.
There are a number of ways to reconcile variables:
You can reconcile all variables or all stream variables from the commands on the run menu.
You can reconcile variables associated with a flowsheet object (block or stream) from the context menu (right-click) on the objects in the process flowsheet window, or context menus on the folders for the streams in the data browser.
You can reconcile all streams in a hierarchy level from the context menu on the Streams folder in the data browser.
For example:
To reconcile an individual stream and copy stream results to the input form:
Select a stream on the flowsheet,
Click the right mouse button and
Select Reconcile from the list
Select
o State variables (Two state variables must be selected for the stream flash calculation.)
o Type of variables (Component flows, or component fractions and total flow can be copied.)
o Basis for MIXED substream (Mole, mass, or standard liquid volume basis can be selected.)
o Basis for CISOLID substream (Mole, mass, or standard liquid volume basis can be selected.)
Click OK.
To reconcile all streams:
In the Data Browser, click on the Streams folder,
Right click and select Reconcile from the menu.
If you want to reconcile all streams, disable the top two check boxes. Leave the check boxes enabled if you want to update/reconcile only streams that have input specified (Feed streams and any other stream you may individually reconciled).
In 12.1 and higher from the flowsheet window, there is also the option of reconciling only all tear streams even if some of them do not have input and some do. For example:
From the Run menu select Reconcile All Streams
Select Only update tear streams
Select State variables, Type of variables, Basis for MIXED substream, and Basis for CISOLID substream as described above.
Click OK.
Note: The simulation needs to run before it is possible to reconcile streams. It is not possible to reconcile streams after simply opening a backup file that includes results.
Keywords: Tear Stream Estimate Reconcile
References: None |
Problem Statement: How do I create a customized application template in Aspen Plus 10? | Solution: Aspen Plus provides a number of application types designed for various industries. Sometimes, this application type cannot be applied to your simulation. You can develop your own, defining default sets for a class of simulation not included in the Aspen Plus list provided. .
Template files are used to set your personal preferences. They can include:
Units of measurement
Property sets for stream reports
Composition basis
Stream report format
Global flow basis for input specifications
Setting Free-Water option
Selection for Stream-Class
Property Method
Required) Component list
Other application-specific defaults
Any flowsheet (complete or incomplete) can be saved as a template file. From the File menu, select Save as, and choose a file type of Application Template (*.apt).
For example, it is possible to add own your Property Sets or Unit Sets to the built-in ones so they can be used directly in the Setup section. It is also possible to have entire sections of a plant as a template.
In order to have a personal template appear on the Personal sheet of the New dialog box, simply put the template file into the ..\GUI\Templates\Personal folder.
The text on the Setup / Specifications / Description sheet will appear in the Preview window when the template file is selected in the New dialog box.
You can selecting this template as the default by entering it as the default Application Template found by selecting Options from the Tools menu and then clicking on the Startup tab.
Alternatively, it is also possble to import a template (.apt) file into an existing Backup (.bkp) file using Import from the File menu.
For more information on templates see the Aspen Plus User Guide, Chapters 15 and 16.
Keywords:
References: None |
Problem Statement: How to debug an Aspen Plus user subroutine with the Compaq Visual Fortran 6.x (6.1 or higher) debugger ? | Solution: It is assumed that Aspen Plus and the Compaq Visual Fortran 6.x have been installed on the same machine.
1. Compile the Fortran code with the ASPCOMP command and the dbg option: aspcomp filename dbg
2. Save the simulation as an input File
3. Modify the input file to include the following Statement
DIAGNOSTICS HISTORY SYS-LEVEL=8 DEBUG DYNLINK=2
4. Run the simulation with the debug option on: aspen <input_file_Name> /debug
5. The simulation will then stop and the Visual Fortran debugger will be opened.
From there, it will be possible to define a complete debugging environment, to insert breakpoints and visualize any variable from the Fortran code each time the routine is called by Aspen Plus.
The attached ZIP file contains a step-by step description for debugging code with version 10.2, 11.1, 12.1 and 2004, and one simulation example with a user routine.
Note for Aspen Plus 11.1, 12.1, 2004 and 2004.1:
When setting the debugging environment for debugging Aspen Plus 11.1 user routines, it is important to include the DLL zeitexec.dll located under \Program Files\AspenTech\APRSystem 11.1\Engine\xeq. Is is not necessary to do so for Aspen Plus 10.2. See attached step-by-step description for details on how to include that DLL in the debugging environment.
The original Aspen Plus 11.1 System Management
Keywords: Compaq / Digital Visual Fortran
Debugger / Debug
User model
References: Manual omitted this step in the procedure. The procudure was corrected and updated for the version released with Aspen Plus 11.1 Service Pack 1. This manual can be downloaded from our web site at http://support.aspentech.com/webteamcgi/ |
Problem Statement: The electrolyte wizard allows dissociated acids to represent the free hydrogen ion as either H3O+ or H+. How should I choose? | Solution: For almost all purposes the hydronium (H3O+) ion is a better choice.
It is a better physical model:
Vapor-liquid equilibrium data is better represented when the hydronium ion is selected. In aqueousSolution there are very few free hydrogen ions (bare protons). Hydrogen ions are solvated by water (hydrated). The water of hydration is not available to vaporize. Proper representation of the species present is the most important step in simulating a system with electrolytes.
It is the basis for our regressed parameters:
With the introduction of an expert system for chemistry generation in Aspen Plus 9, we re-regressed all the data on electrolyte systems using hydronium ion rather than hydrogen ion. With the electrolyte wizard in Aspen Plus 10 we again updated the parameters based on hydronium ion. The parameters available for hydrogen ion are much more limited and have not been updated.
The hydrogen ion may be selected if the user has good parameters that have been regressed on that basis, but there is no other reason to make that selection.
Keywords:
References: None |
Problem Statement: I found that when I use NRTL, WILSON or UNIQUAC, the heat of mixing is not predicted accurately when I use the built-in parameters for NRTL, UNIQ, and WILSON. How do I fix this? | Solution: This is to be expected because the binary parameters in the databanks were regressed using VLE or LLE data only. Heat of mixing data was not used.
The heat of mixing for electrolyte systems is better predicted as many electrolyte parameters were regressed with VLE and Heat of mixing data.
To improve heat of mixing conditions, you can regress the binary parameters using VLE or LLE (or Aspen Plus generated data using VLE data) and Heat of mixing data. SeeSolution 3378 for an example of a regression using both heat of mixing data and generated VLE data.
Keywords: HLXS
References: None |
Problem Statement: How is packing height measured in a column with respect to stages? Where does the top of sections begin? What is the Tray and Packing sizing/rating measuring convention? | Solution: The convention is to measure packing from the top of the column. In other words, stage 1 is at the top of the packing or height equal to 0. The same convention applies to any section of the column. The figure below illustrates a column with 6 ft of packing with 2 ft HETP (height equivalent to theoretical plate).
Total Packing Height = 6 ft
HETP = 2 ft
Theoretical stages = 6 / 2 = 3 stages
|-------------------| stage 1 height = 0.0 ft
| |
|-------------------| stage 2 height = 2.0 ft
| |
|-------------------| stage 3 height = 4.0 ft
| |
Keywords: packing, height equivalent to theoretical plate
References: None |
Problem Statement: There are problems related to using Excel 2000 with a Calculator block.
These problems include:
The Excel template not loading and/or running
Problem loading CalcExcelAddin.xla.
Wordaround:
Apply the Aspen Engineering Suite 10.2 Service Pack 1 for Aspen Plus. Click this link to go to the Aspen Engineering Suite 10.2 Service Pack 1 download page:
http://support.aspentech.com/webteamcgi/ | Solution: Display_view.cgi?key=104681
Alternatively install Aspen Engineering Suite 10.2 Update1 for Aspen Plus. Update1 is available on CD from the end of February 2001.
Fixed in Version:
Aspen Plus 10.2 Service Pack 1
Keywords: Calculator Block, Excel, Addin, Add-Ins,
References: None |
Problem Statement: What correlations are employed in Aspen Plus for the BK-10 method? | Solution: The Correlations for BK-10 were developed by AspenTech from the BK-10 charts published in the following references:
Prediction of Equilibrium Ratios from Monograms of Improved Accuracy. by B.C. Cajander, H.G. Hipkin and J.M. Lenoir, Journal of Chemical & Engineering Data, 5(3), 251, July, 1960
Predict K Values at Low Temperatures, Part 1. by John Lenoir. Hydrocarbon Processing, p. 167, Sept 1969.
Predict K Values at Low Temperatures, Part 2. by John Lenoir. Hydrocarbon Processing, p. 121, Oct. 1969.
The correlations themselves are AspenTech's property.
Keywords: BK-10, correlations, references
References: None |
Problem Statement: During the installation of AES Core Component, after coping the files, the following error box appears:
C:\winnt\system32\ssiregi.exe
Then a second dialog box pops up stating:
System Process is Unable to load device: \systemroot\system32\drivers
device driver couldn''t be loaded Error status was 0xc0000020.
At this point you have no choice but choose OK at which point the installation continues.
Every time the machine is booted up after that it gets the same error message and entry in the event log. | Solution: Clean up the device driver by running ssiregi.exe.
Run this program in one of two ways:
1 - From the Windows Start menu select Run, then type \winnt\system32 ssiregi.exe remove
2 - Open a DOS window and issuing the following commands.
cd \winnt\system32
run ssiregi.exe remove
Keywords: Activator Driver SSIPDDP
References: None |
Problem Statement: How do I change the default working directory in Aspen Plus? | Solution: There are two ways to set this.
1. The working directory can be set in the User Interface.
In V7.3 and earlier version, The working directory, can be set by selecting Tools, and then Options. Then select the Startup tab. Change the value in the text box labeled Default Working Directory.
Screenshot for V7.3 and earlier:
? Starting from V7.3.2 to change default directory, go to File and click on Options button in the bottom right. Select Files and change default directory location from right hand side menu.
Screenshot for V7.3.2 and later:
2. The working directory is set when a user double clicks on a .bkp or .apw file from within a browser window. The folder where that file resides becomes the default working directory for that session.
Keywords: folder, directory, default
References: None |
Problem Statement: Is it possible to calculate viscosity of a petroleum mixture's stream from Kinematic Viscosity data? | Solution: Aspen Plus does not have a feature to calculate viscosity from user specified kinematic viscosity curves.
Please see below on how viscosity and kinematic viscosity are calculated in Aspen Plus:
MUMX (Viscosity of a mixture) : calculated using a selected model. User can choose to use API, Andrade/DIPPR or User viscosity model to calculate liquid mixture viscosity. API liquid viscosity model uses a correlation based on API procedures and Figures 11A4.1, 11A4.2 and 11A4.3 (API Technical Data Book, Petroleum Refining, 4th edition) Andrade/DIPPR model calculates liquid mixture viscosity from pure componet liquid viscosity calcuated by Andrade or DIPPR liquid viscosity model. (ADA estimates Andrade parameters (MULAND) of the pseudocomponents) User can also write a user subroutine for viscosity (Refer toSolution 104144)
KINVISC (Kinematic viscosity of a mixture) : calculated from MUMX by the equation, KINVISC=MUMX/DENSITY.
VISC (Viscosity of a petroleum mixture) : Calculated based on absolute viscosity curve that user specified in ADA
KVISC (Kinematic viscosity of a petroleum mixture) : Calculated based on kinematic viscosity curve that user specified in ADA.
There is no option to back-calculate viscosity from kinematic viscosity.
However, there are many cases in which the viscosity is not available (viscosity is often measured in term of kinematic viscosity). Therefore, a user might want to use kinematic viscosity data to calculate viscosity (In heavy oil application, such as asphalt and lubricant, the existent viscosity model might not give a good prediction).
In this case, the user can use a Calculator block to perform the calculation for viscosity of a stream as follows:
Specify the kinematic viscosity curves for the assay on the Components / Assay / Property Curves / Viscosity sheet.
Create a Prop-set for KVISC.
In the Calculator block, define DENSITY and prop-set defined above (KVISC) for the streams you want to calculate their viscosity from kinematic viscosity as the variables. Then for each streams, enter the equation for viscosity as: Viscosity=KVISC*DENSITY. (Using Excel might be more convenient than Fortran, since you can see the calculated Viscosity value on the Calculator/Calculate sheet.)
In the attached file, a calculator block is defined to calculate viscosity of stream IN from user defined Kinematic Viscosity Curves (the result is reported on Calculator/Calculate sheet: 2.155 cP). Viscosity calculated using API viscosity model (MUMX) is reported on the Stream Summary (1.325 cP)
Keywords: Viscosity, Kinematic Viscosity
References: None |
Problem Statement: What are the different flooding factors reported for tray rating? | Solution: There are three measurements of flooding in trayed columns:
1. Flooding factor/approach
This is the jet flooding. If the vapor velocity is very high, it will start carrying a lot of liquid. It is reported as a ratio of the actual velocity to the velocity at flooding (calculated from a suitable correlation ), or a ratio of capacity factors.
2. Downcommer backup
This is the liquid height in the downcomer. Also reported is the ratio of downcomer backup to tray spacing. If this is greater than one, liquid backs up to the tray above.
3. Choking factor
This is the ratio of liquid velocity leaving the downcomer to the design velocity ( calculated from suitable correlations). If this is greater than one, choking occurs and the liquid cannot exit the downcomer fast enough.
Keywords: RadFrac column tower
TPSAR tray sizing and rating
References: None |
Problem Statement: Is there a way to have VBA code determine the Aspen Plus version number of the currently open session? | Solution: There is not a version number property VBA code can probe directly. However, the VBA code can ask for the NAME of the simulation session. This will return a string containing the version number which can be parsed from the string. For example, asking VBA to store the name of the simulation in a variable called SimName with the following command:
SimName = go_simulation.name 'go_simulation is the name of the Aspen Plus object
returns (in version 12.1):
Aspen Plus 12.1 OLE Services
The final step is to parse the above string to extract just the version number. This can be done with the below subroutine:
Public Sub VersionLookup()
Dim SimName As String, APverNumber As String
Dim StartChar As Integer, EndChar As Integer
' Obtain the simulation name, complete with version number:
SimName = go_Simulation.Name
' extract the version number from the string _
the version number starts after plus _
and ends before OLE in the simname (Aspen Plus 12.1 OLE Services)
StartChar = InStr(LCase(SimName), plus) + 5
EndChar = InStr(SimName, OLE) - 1
APverNumber = Mid$(SimName, StartChar, EndChar - StartChar)
MsgBox The currently loaded Aspen Plus session is version & APverNumber
End Sub
Keywords: activex, version number, vba
References: None |
Problem Statement: How does one obtain the value of the reaction equilibrium constant Keq calculated by Aspen Plus in an RGibbs block? | Solution: To get the Keq (equilibrium constant of a reaction), one can use a Calculator block (called a Fortran block in Aspen Plus 10.1 and earlier) to calculate it.
Assuming that one has the following reaction: A + B <--> C + D, the definition of Keq is as follows:
Keq = a(C)*a(D)/[a(A)*a(B)]
where a(i) is the activity of component i. The activity a(i) is in turn defined as:
a(i) = y(i)*PHI(i)*P
where y(i) is the mole fraction, PHI is the activity coefficient, and P is the system total pressure. Combining the 2 equations, one gets
Keq = y(C)*PHI(C)*y(D)*PHI(D)/[y(A)*PHI(A)*y(B)*PHI(B)]
Both y(i) and PHI(i) can be accessed via property sets.
A sample input file is attached that demonstrates how to calculate Keq via a Calculator (Fortran) block.
Keywords: TITLE 'INPUT FILE TO CALCULATE KEQ IN RGIBBS BLOCK'
;
COMPONENTS CO CO / H2O H2O / H2 H2 / CO2 CO2
;
PROPERTIES IDEAL
;
DATABANKS PURECOMP
;
FLOWSHEET
BLOCK REACTOR IN=FEED OUT=PROD ;
STREAM FEED TEMP=500 PRES=14.7
MOLE-FLOW CO 1.0 / H2O 1.0 ;
BLOCK REACTOR RGIBBS
PARAM TEMP=1500 PRES=25 ;
PROP-SET SET1 PHIMX PHASE=V COMPS=CO2
PROP-SET SET2 PHIMX PHASE=V COMPS=H2
PROP-SET SET3 PHIMX PHASE=V COMPS=CO
PROP-SET SET4 PHIMX PHASE=V COMPS=H2O
;
FORTRAN KEQ
DEFINE YCO2 MOLE-FRAC STREAM=PROD COMPONENT=CO2 DEFINE YH2 MOLE-FRAC STREAM=PROD COMPONENT=H2
DEFINE YCO MOLE-FRAC STREAM=PROD COMPONENT=CO
DEFINE YH2O MOLE-FRAC STREAM=PROD COMPONENT=H2O
DEFINE PHICO2 STREAM-PROP STREAM=PROD PROPERTY=SET1
DEFINE PHIH2 STREAM-PROP STREAM=PROD PROPERTY=SET2
DEFINE PHICO STREAM-PROP STREAM=PROD PROPERTY=SET3
DEFINE PHIH2O STREAM-PROP STREAM=PROD PROPERTY=SET4
F EQK = (YCO2*PHICO2)*(YH2*PHIH2)/((YCO*PHICO)*(YH2O*PHIH2O)) F WRITE(NTERM,2)
F WRITE(NTERM,1) EQK
F WRITE(NTERM,2)
F 1 FORMAT (1X,'KEQ = ',E12.5)
F 2 FORMAT ('*******************************')
EXECUTE Last ;
References: None |
Problem Statement: Issuing asplmadm command with -s or -l options returns nothing, but user can check out a license from the server.
asplmadm -s command should provide a listing of all license manager servers on the network. asplmadm -l command should provide a listing of all available licenses on any server found on the network. | Solution: asplmadm with -s or -l options will not work when the License manager and clients are in different subnets of the network.
To solve the problem, define the environment parameter ASP_LMhost to point to the IP address or full name of the License Server. Reboot the system afterwards.
Example Set ASP_LMhost = 10.20.16.23 or Set ASP_LMhost = MyLM.hou.aspentech.com
If you are running Windows 98 or Windows 95, add this environment parameter to the autoexec.bat file and reboot. If you are using NT, under My Computer properties, add this to the environment parameter list and reboot.
Keywords: License Server Client
References: None |
Problem Statement: Does a 3 Phase Radfrac use EO | Solution: Radfrac will work with 3 phase and EO but there are some limitations. By default it assumes that the three phase trays don't change when you go from SM to EO. A check is made for trivialSolutions in all cases by using Gibbs free energy minimization to see if some trays which were not trying to detect three phases should have been and a message issued if such exist. In that case, the user could reconcile input and rerun the radfrac column in SM (go to the column, step), come back to EO and try again. There is also a flag that would change the default check to all trays specified in L2-stages.
Keywords: Radfrac EO 3 PHASE
References: None |
Problem Statement: Is it possible to access compressor type for a Compr block via a Define statement? | Solution: It is not possible to access this information from the Define form in the Graphical User Interface; however, it is possible to add it in input language. Attached is an example of accessing ITYPE.
The variable name for the compressor type is ITYPE. To access this variable, go to the EO Option sheet of a Calculator block or a Design Spec and click on the Add Input button. Add the following line in the dialog box:
DEFINE ITYPE BLOCK-VAR BLOCK=blockname VARIABLE=TYPE SENTENCE=PARAM
The value of ITYPE corresponds to the compressor types in the table below:
ITYPE
Compressor type
2
Positive Displacement
3
Isentropic
5
ASME-Polytropic
6
GPSA-Polytropic
7
ASME-Isentropic
8
GPSA-Isentropic
Keywords: itype
compr
References: None |
Problem Statement: The following error occurs during AES 10.2 or AES 11.0 Core Component installation.
Failed to set special folder location 25 during Aspen Tech License Manager core component installation | Solution: IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the Restoring the Registry Help topic in Regedit.exe or the Restoring a Registry Key Help topic in Regedt32.exe.
WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.
For information about how to edit the registry, view the Changing Keys and Values Help topic in Registry Editor (Regedit.exe) or the Add and Delete Information in the Registry and Edit Registry Data Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT or Windows 2000, you should also update your Emergency Repair Disk (ERD).
Copy enclosed file onto the computer with the problem(it can be anywhere), and double click on the saved file.
Run \core\common\setup.exe. If this succeed, you are all set. Do the regular product installation by running setup.exe from the CD.
The above procedure should solve the problem, however if you continue having the same problem, fetch the following two registery vlues and email it to [email protected] with explanation of the problem.
If # 2 above didn''t succeed, do the following
. Open up registry by running regedit
. Go to the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders Write down the value of Common Startup
. Go to the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders Write down the value of Common Startup
Email the two values to [email protected] with explanation of the problem
Keywords: License Manager
ALM
Core Component
References: None |
Problem Statement: On Windows 2000 when you run an Aspen Plus file where the linker is required, there is a failure with the error message:
LINK : fatal error LNK1181: cannot open input file dfordll.lib Link failure, status = 1181
asplink return code = 5 | Solution: There are two possible causes of this problem:
Compaq Visual Fortran (CVF) 6.1 or 6.5 has not been installed with command line option enabled.
You can check if this is the problem by trying to compile a sample Fortran program within a CMD prompt.
To fix this problem, you need to re-install the compiler paying attention to answer Yes when asked whether to install the command line option.
Part of the path that has to be present in the user environment variables for local user is missing from the system variables.
You can check if this is the problem by going to Start->Control Panel->System->Advanced->Environment Variables and looking at the user variables for local user and at the system variables. For example, on one system exhibiting the problem, the contents were as follows: User variables for local user:
D:\Program Files\Microsoft Visual Studio\DF98\IMSL\LIB;D:\Program Files\Microsoft Visual Studio\DF98\LIB;D:\Program Files\Microsoft Visual Studio\VC98\LIB System variables
D:\Program Files\Microsoft Visual Studio\VC98\mfc\lib;D:\Program Files\Microsoft Visual Studio\VC98\lib
To fix this problem, copy and paste the part of the path that is present in the user variables for local user but missing from the system variables: D:\Program Files\Microsoft Visual Studio\DF98\IMSL\LIB;D:\Program Files\Microsoft Visual Studio\DF98\LIB;
Keywords: Compiler linking FORTRAN
References: None |
Problem Statement: Where is the PERFORATED PASS PLATES option in Aspen Acol+? In previous ACOL versions, the Perf.Pass Plates option was in the NOZZLE/HEADER Screen. | Solution: The PERFORATED PASS PLATES option in Aspen Acol+ is in the Input | Program Options | Methods/Correlations | Tube Side tab, where you can enter the Velocity heads for perforated pass plate pressure drop
In this input item you need to enter the number of velocity heads to be used for calculating the pressure drop across the perforated pass partition plates.
Keywords: perforated, pass, partition, velocity, head, pressure, drop, nozzle, header
References: None |
Problem Statement: Can the dew point for an electrolyte mixture such as sulfuric acid be predicted at high temperatures (T) and pressures (P)? | Solution: There are two problems with trying to predict dew points with electrolyte systems. One is the question of whether the physical property correlations are good at the high temperatures in question. The other problem is with flash convergence.
The physical properties in the ElecNRTL model are fit to aqueous systems at near 1 atm. They are not in general tested above temperatures of about 250 F, and their accuracy above that temperature is questionable.
For example for a sulfuric acid and water system, the parameters that need to be looked at are:
vapor pressure of H2SO4 (PLXANT)
vapor phase properties of H2SO4 (PLXANT)
vapor pressure and other properties of H2SO3 if SO2 is present (PLXANT)
equilibrium dissociation constants for the acids (KSTIOC)
binary interaction parameters between water and ions (GMELCC)
Flash convergence is the other issue. Because chemistry is only active if there is liquid water, and because water is much more volatile than H2SO4, Aspen Plus has trouble deciding when a liquid phase will form and what it's composition should be. In general, specifying a flash with VFRAC=0 will not work, and specifying any vapor fraction above about 0.9 is likely to cause trouble. Dewpoints with just H2SO4 and water will be harder to calculate than those with inert gases present.
Better results come with flashes in which you specify Temperature and Pressure. By starting at a low temperature and slowly increasing it, you can often see where the dew point must be, even though the flash calculations begin to fail at or near the dew point. The attached file shows how to approach the dew point problem.
Keywords: elec
sulfuric
h2so4
References: None |
Problem Statement: Why is the saturated vapor heat capacity given by CPMX(V=1) different from CSATMX? | Solution: There are three heat capacities in common use: , and .
. represents the change in enthalpy with temperature at constant pressure.
. represents the change in enthalpy of a saturated liquid with temperature.
. represents the energy required to effect a temperature change while maintaining the fluid in the saturated state.
Except at high reduced temperatures, all three forms of heat capacity are usually in close numerical agreement. More details on this can be found in Reid, R. C., Prausnitz, J. M., Poling, B.E., The Properties of Gases and Liquids, 4th edition, Chapter 5, Section 5-7, page 136.
In Aspen Plus you can calculate at saturation by using CP or CPMX in a Property Set and calculating for vapor fraction of 1 (V=1). is a quantity often measured experimentally and it can be calculated in Aspen Plus using CSATMX in a property set. Note that whereas will be calculated for V=1 at constant pressure, CSATMX is calculated as temperature is changed along the saturation curve and, therefore, both temperature and pressure will vary.
Values reported in Perry's Handbook, for instance for water, are those for at saturation by using CP or CPMX and they give good agreement, but reporting CSATMX will give a different value in this case for the reasons explained above.
Keywords: heat capacity
Cp , Cpsatmx
saturated
h2o
water
property set
References: None |
Problem Statement: How do I protect a bridge so the end user cannot change the Read From field in the links? | Solution: To protect a bridge so the end user can not change the Read From field, you should Disable Bridge Definer privileges for end user by going to Administrator tool as shown in screenshot below.
Keywords:
References: None |
Problem Statement: When attempting to run Aspen Plus the following error message occurs:
Form controls mmgeneric failed to load
gui\xeq\mmcontrolsvc.ocx could not register
gui\xeq\mmscrollarea.ocx could not register
gui\xeq\mmscrollareachild.ocx could not register | Solution: The problem is that when installing Aspen Plus, the above mentioned OCX''s were not registered correctly.
The steps to fix this problem are as follows:
Run RegFix.bat from \Program files\Aspentech\Aspen Plus xxxx\GUI\XEQ If this does not fix the problem, then go to step 2
Uninstall Aspen Plus, then run the RegClean.exe utility as many times as it takes until the Fix Error button is disabled. RegClean is a Microsoft utility that can be obtained from the following link: http://www.microsoft.com/downloads/release.asp?ReleaseID=18924
Re-install Aspen Plus.
Keywords: mmcontrolsvc.ocx
mmscrollarea.ocx
mmscrollareachild.ocx
Form
controls
mmgeneric
References: None |
Problem Statement: After adding a Hetran or Aerotran block to flowsheet, only the Block Options shows up under the Hetran block in the Data Browser. | Solution: Aspen Plus was installed without Aspen Hetran or Aspen Aerotran selected. To fix the problem, reinstall Aspen Plus over current installed copy. During the installation, select Custom Install and make sure to select all applicable products including Aspen Hetran or Aspen Aerotran. After the install is complete, the input forms for the Hetran or Aerotran block will now be available.
Keywords: Hetran
missing
References: None |
Problem Statement: How is the Simpson''s shortcut method used in pressure relief calculations for nozzle flow? Can nozzle flow calculation time be reduced? | Solution: The equation for nozzle flow, which is used to model the valve and to convert from stagnation to flowing pressure and back, requires an integration with pressure as the independent variable. At each pressure value, the molar volume must be calculated. The rigorous way to do this is to perform a constant entropy flash calculation at each value of pressure. Because a constant entropy flash in AspenÂPlus requires about 10 times as much time as a constant enthalpy flash, you can speed up the calculations by doing constant enthalpy flashes for the nozzle flow calculations instead of constant entropy flashes. The error in the calculations is minimal.
AspenÂPlus can also perform the shortcut method published by L. L. Simpson (Simpson, L. L., Estimate Two-Phase Flow in Safety Devices, Chemical Engineering, August, 1991, pp. 98-102.) which has been shown to give very good results. Instead of doing a flash calculation to calculate the molar volume at each point in the integration, two flashes are done at the start and parameters are calculated which make it possible to calculate the molar volume at other pressures without doing flashes. Simpson''s method reduces computation time dramatically while maintaining good accuracy.
Use Pres-Relief Convergence Methods sheet to set these options.
Keywords: prv
References: None |
Problem Statement: There are multiple warnings and repeated Out of environment space errors when using aspcomp to compile a Fortran routine in a Simulation Engine DOS window. | Solution: Modify the config.sys file located in your c:\ drive root directory to add the following line:
shell=c:\win95\command.com/p/e:1280
You may increase the allocation. Typically this is done in multiples of two to 4096, 8192, 16384, etc.
Then restart your PC and launch the Aspen Plus Simulation Engine window.
Keywords: Environment Space
DOS
Fortran
References: None |
Problem Statement: If you adjust a Property Method (formerly Option-Sets) using the Property Method's Models sheet, and then make changes on the Routes sheet, you will lose the changes you made on the Models sheet.
For example, if you want to use the WILS-HF Property Method with the NRTL activity coefficient (by changing the gamma model on the Property Method / Models sheet) and modify the liquid molar volume route to VLMX26 (mole-fraction averaging of pure component densities) on the Property Method / Routes sheet, you lose the changes you made on the Models form.
Aspen Plus 11 will give a warning about this problem, but there is no message in Aspen Plus 9 or 10. The warning is as follows:
This route modification that you made will overwrite all previous changes on the Models sheet.
If you want to enter both routes and models, complete all modifications on the Routes sheet before changing the Models sheet.
How can you adjust the value in an Property Method / Models form for use in other forms? | Solution: By limiting how you can adjust Property Methods on a form, Aspen Plus prevents inconsistent specifications on a series of forms. This feature may be adjusted in future releases to allow you to modify the form measurements as you wish. However, there are two ways you can adjust specifications for the present releases:
Make your changes on the Routes form before you make additional changes on the Models form.
Modify either the Routes form or the Models form, not both forms.
Keywords:
References: None |
Problem Statement: Is it possible to get fortran code to return integers? | Solution: There are several Fortran functions that can be used to convert a Real number to an Integer number. This type of conversion is often needed in distillation simulations where the number of stages is varied in a Sensitivity or Calculator blocks, and the feed stage depends on the number of stages. The feed stage must be an integer.
Function Name
Description
INT(X)
Returns the integer part of the real number X
FLOOR(X)
Returns the greatest integer less than or equal to the real number X
NINT(X)
Returns the real number X rounded to the nearest intege
Keywords: int
References: None |
Problem Statement: When performing flash calculations, the Chemistry fails to converge, giving a message similar to the following error message:
*** SEVERE ERROR WHILE PERFORMING INITIAL ENTHALPY CALCULATIONS FOR STREAM:
1 (SINIT.6)
CHEMISTRY (chemid) NOT CONVERGED; PHYS PROP RMSERR = 2.1415D-08 ; CHEM
EQNS RMSERR = 0.4472 | Solution: There are a number of reasons that might cause Chemistry not to converge. Generally, it is important to simplify the Chemistry and to make sure that all parameters are reasonable.
Check that the Chemistry is properly specified.
Try to simplify the problem by removing unnecessary reactions in the Chemistry paragraph. Including extra reactions can make the problem more difficult to converge. For example, a water dissociation reaction may not be needed if all aqueousSolutions will be strongly acidic (pH less than 2).
Try to simplify the problem by including Equilibrium Constant parameters (K-SALT/K-STOIC) for all reactions. Calculation of reaction extents is simpler and more reliable if K-SALT/K-STOIC data is provided.
Try to simplify the problem by converting Salt reactions to Dissociation reactions if it is known that a given salt will not precipitate anywhere in a given simulation.
Confirm that all of the required physical property parameters are present for the simulation. NOTE: This is specifically relavent for Solid Enthalpy of Formation (DHSFRM) and the Solid Gibbs Free Energy of Formation (DGSFRM) which will erroneously default to 0.0 if values are not available.
Keywords: elec
chemistry
References: None |
Problem Statement: Why does the stream result of API gravity differ from the input for a petroleum assay?
On the Assay/Blend input form, user entered a API bulk gravity of 40.8 for a particular assay. In the simulation stream input, user entered this assay component as the only component. However, when using prop-set to report API for this stream, the result of the stream showed 35.9, different from the user input value. Why? | Solution: The descrepancy could be caused by the pseudocomponent cut temperature increment. Petroleum stream properties is a function of pseudocomponent composition, which is related to the number of cuts generated during assay data analysis. If the number of cuts is too few, or the cut interval is too large, then the calculated stream properties may differ from the input values. In this particular case, after the cut temperature increment is reduced to 10 F for 0 - 800 F range, the calculated API gravity matches the input API gravity of 40.8. In Aspen Plus 10, the cut increment is specified under Components \ Petro Characterization \ Generation.
Cut Temperatures are temperature cut points Aspen Plus uses to generate pseudocomponents. Sometimes smaller increments are needed to reduce the variation in the API gravity.
You first need to use the Components / PetroCharacterization / Generation form to generate a set of pseudocomponents from assay data and then it is possible to change the cut temperatures. You can generate one or more average sets of pseudocomponents for groups of assays that you specify. You can use a particular assay to generate only one set of pseudocomponents.
This form contains the following sheets: Specifications, Cuts, and Naming Options. Use the Specfications sheet to specify assays/blends to include, their respective weights, and the pseudocomponent property method. Cuts is used to specify pseudocomponent generation options and specifications. Use Naming Options to specify pseudocomponent naming conventions.
By default, Aspen Plus generates one average set of pseudocomponents for all assays defined in a run. You can supply the:
Temperature cut points used to define the pseudocomponents
Correlations property method used for pseudocomponent property estimation
Aspen Plus provides five built-in correlation sets. You can also build a new correlation property method from any built-in correlation.
Cut Temperatures are temperature cut points Aspen Plus uses to generate pseudocomponents. You can indicate cuts in terms of either:
A list of values
The number of increments or size of increments within a given temperature range
If you do not specify Cut Temperature, Aspen Plus will use the default values. To change these default values, complete the following steps:.
From the Data menu, select Components, then Petro Characterization.
In the left pane of the Data Browser, click generation.
An object manager will appear, click on New and select an ID.
Enter the assay/blends to be included, and a weighing factor. For more information on this, refer to Aspen Plus User''s Guide 32-12.
Click on the Cuts tab. Select the Range and Increments button.
Enter the TBP ranges and the temperature increments. The default values are: TBP Range (F) Increments (F) 100-800 25 800-1200 50 1200-1600 100
Decrease the temperature increments, for the 100-800 range, 10 degrees F works well. I have found in one example that just decreasing the increment in this range will give the correct (input) API gravity in the Results / Stream Summary.
Keywords: petroleum
ada
assay
blend
API
gravity
References: None |
Problem Statement: Double clicking on an APW file starts Aspen Plus; however, it disappears before the model is displayed. | Solution: This happens when the customer has updated to a higher version of Aspen Plus, but is using an APW file which was created with an earlier version. Aspen Plus Document (.apw) files are binary files and are not compatible across different versions or Service Pack levels of Aspen Plus. You must open the APW file using the older version and save the model as a backup (.bkp) file. The backup file can be opened in the newer version of Aspen Plus.
In general, before upgrading to a higher version including installing Aspen Plus 10.2 Service Pack 1 or Update1, complete the following tasks:
If you have simulations that you created with earlier versions of Aspen Plus, make sure you have saved the simulations as Aspen Plus Archive (.bkp) files. Aspen Plus Document (.apw) files are binary files and are not compatible across different versions or Service Pack levels of Aspen Plus.
If you have physical property models that you created with Aspen Properties 10.2, make sure you have saved the property models as Aspen Properties Backup (.aprbkp) files before applying this Service Pack. Aspen Properties Document (.aprop) files are binary files and are not compatible across different versions or Service Pack levels of Aspen Properties.
Keywords: APW
BKP
References: None |
Problem Statement: When using a HEATX block configured to use film coefficients calculated via a user specified power law, the values do not match the equivalent hand calculations. The hand calculations return U values that are an order of magnitude larger than the Aspen Plus results.
The equations were obtained the simplified resistance equation given in the online help for the heat exchanger:
1/U = 1/HT + 1/HS
where:
HS = shellside film coefficient
HT = tubeside film coefficient | Solution: The documentation is misleading about film coefficient calculations. The equation in the help file does not include the tubewall resistance and area correction for tube outside diameter (OD) and inside diameter (ID). The correct overall coefficient based on film coefficient should be:
UOT = USCAL/(FS + 1.0D0/(HS*NUS) + ARATIO*(1.0D0/HT + FT) + RWALL)
where:
UOT = the overall heat transfer coefficient
FS = shellside fouling coefficient
HS = shellside film coefficient
NUS = fin efficiency
ARATIO = tube outside/inside area ratio
HT = tubeside film coefficient
FT = tubeside fouling coefficient
RWALL = tubewall resistance
Keywords: heatx, film coefficient, fouling, efficiency
References: None |
Problem Statement: Binary property analysis available from the Tools menu can display PXY, TXY or XY curve. Using them, we can know approximate azeotropic point; however, they do not show the exact composition of the point. | Solution: The best way to know the azeotropic point is to use Aspen Split. Alternatively, it is possible to calculate it by modeling McCabe-Thiele procedure using only Aspen Plus.
You can use the McCabe-Thiele procedure by following steps:
1. Put a flash block and a stream multiplier onto the flowsheet.
2. If system makes a minimum azeotrope, connect the vapor product line of the flash drum to the multiplier. If the system makes a maximum azeotrope, connect the liquid line to the multiplier.
3. Connect the multiplier outlet to the feed port of the flash drum. This will make a recycle.
4. Input initial estimates for streams which connected the multiplier to the flash drum.
5. For a minimum azeotrope search, set the pressure drop to zero and 1.0e-6 for the vapor fraction. For a maximum azeotrope search, set the pressure drop to zero and 0.999999 for vapor fraction. This gives the equilibrium phase composition with feed stream.
6. Enter 1.0E6 in the multiplier block to keep the recycle flowrate or fix the recycle flowrate using a calculator block.
7. The accuracy of the azeotrope is dependent on the recycle tolerance. Tighten the tolerance for recycle to improve the accuracy.
Please refer the attached example file.
Keywords: Azeotrope
Binary
References: None |
Problem Statement: How do you configure AES 11.1 applications to use the standalone FlexLM Licenses? | Solution: Save your standalone license key file onto C:\Program Files\Common Files\AspenTech\ALM (or any other suitable location).
Launch FlexLM License Management Selector from Start Menu\Programs\AspenTech\Common Utilities.
Click on Select Aspen License File to get a license.
Click on the Browse button to select the standalone license file copied onto your local machine in step 1.
This will point your machine to get licenses from the FlexLM standalone license key file.
Keywords: FlexLm
AspenTech License Manager 3.
References: None |
Problem Statement: Customer is unable to use the asplmadm command to poll the License Manager Server and use Broadcast Mode in the License Management Selector program to access the License Manager.
The customer can access a License Manager if the name of the License Manager is entered in the License Management selector program. | Solution: The network is not properly setup to allow network broadcasts.
The License Manager uses TCP Port 6142, registered to AspenTech. By default, network routers will block all broadcast traffic, to reduce network congestion. If the customer wants to use the asplmadm command, they must enable broadcasts for TCP port 6142.
Keywords:
References: None |
Problem Statement: What is the relationship among SINGT1, SINGT2 and SPDROP (i.e., how do their relative values affect things, if at all) in the LSSQP solver? | Solution: LSSQP (Large-scale Sparse Successive Quadratic Programming algorithm) implements a variant of a class of successive quadratic programming (SQP) algorithms, for large scale optimization. It performs the optimization by solving a sequence of quadratic programming subproblems. For more information about the LSSQP solver, go to the Aspen Plus Help Contents under Aspen Plus
Keywords: EO, equation oriented, LSSQP
References: -> Equation Oriented Modeling Reference Manual -> EO Convergence -> The LSSQP Solver
During the basis determination (classifying variables as dependent/independent), an absolute pivot tolerance SINGT1 is used. If a pivot is less than SINGT1 the equation in question is considered dependent and it is not used to eliminate a dependent variable. During the normal iteration (using a previous basis), if a pivot is less than SINGT2, LSSQP re-enter the basis determination mode and re-initialize the reduced Hessian matrix. SPDROP is used in either case, if a non-zero during the elimination becomes less than SPDROP, it is dropped (set to zero) from subsequent elimination.
Normally SINGT2 should be somewhat smaller than SINGT1 (say 0.01*SINGT1). Occasionally, it is necessary to make SINGT1 (and SINGT2) smaller if the problem is poorly scaled. Usually this happens when you see message like use nnn equations to eliminate nnn variables.
The default for SPDROP is 0. By specifying a positive SPDROP, you may be able to speed up the sparse solver time. However, too big a SPDROP will cause sparse solver to return inaccurate/incorrect |
Problem Statement: If Henry's law is used to predict the solubility of a supercritical or light gas in a liquid, Aspen Properties has to solve the following phase equilibrium equation for each Henry's component:
x * GAMUS * H = y * PHIVMX * P
x, y : mole fractions in liquid and gas
GAMUS : unsymmetrically normalized activity coefficient
H : Henry's constant
PHIVMX : fugacity coefficient (gas phase)
P : pressure
GAMUS is the unsymmetrically normalized activity coefficient i.e., in contrast to the definition of the symmetrically normalized activity coefficient (GAMMA), GAMUS approaches unity as the corresponding mole fraction approaches zero. GAMUS is computed from GAMMA divided by the infinite dilution activity coefficient (GAMINF):
GAMUS = GAMMA/GAMINF
For a binary system (solute-solvent pair), the Henry's law constant of the solute is a function of temperature only:
ln(H)= a + b/T + c*ln(T) + d*T + e/(T^2)
ln(H) : natural logarithm of Henry's law constant
a, b, c, d, e : coeffcients of the correlation
T : temperature
But what if the solvent is a mixture? How does Aspen Properties calculate the Henry's law constant of a solute in a solvent mixture? | Solution: Solubility for gases in liquid mixtures are rare and it is therefore useful to consider how thermodynamic relations may be used to estimate such solubilities from solubility data in single solvents. If we know at some temperature the solubility of gaseous solute s in solvent i, and in solvent j, and in solvent k etc., we would like to predict the solubility of s in a mixture of the solvents. We seek an expression for the Henry's constant of solute s in the solvent mixture, designated by H[s,m]. Aspen Properties uses the following reasonable (but not rigorous) procedure to calculate it (*):
ln(H[s,m]) = Sum over all A ( wA * ln(H[s,A]) )
wA = xA * qA^2/3 / Sum over all B ( xB * qB^2/3 )
A, B : solvent indices
wA : weighting factor in mixing rule
xA, xB : solvent mole fractions
qA, qB : parameter in mixing rule (= VC)
VC : critical volume of solvent
The model calculates Henry's constant for a dissolved gas component (s) in one or more solvents (A or B) using the binary Henry's constants for the solute in each subcritical solvent component. If the Henry's constant is available for only a sub-set of the solvent components, Aspen Properties will automatically normalize the Henry's constant of the mixture to that of the available components. Henry's constant model parameters (HENRY) must be available for the solute with at least one solvent.
The Henry's constant mixing rule is a model with an option code. This option code can be specified on the Properties Property Method Models Sheet, and is used to control the impact of the critical volume on the Henry's constant of solute s in the mixed solvent:
Option Code
Mixing Rule
1
Equal weighting - VC^0
2
Size - VC^1/3
3
Area - VC^2/3 (default)
4
Volume - VC
According to Prausnitz, the parameter q in the mixing rule (which was later on equated with the critical volume) is supposed to represent the effective molecular size or molecular diameter. What it actually represents can be controlled by the option code, keeping in mind that with a changing exponent the unit of measurement of the parameter changes, too.
VC^1/3 [m] = unit of length, hence Size
VC^2/3 [m^2] = unit of area, hence Area
VC [m^3] = unit of volume, hence Volume
The conclusion is that the larger the exponent, the stronger the impact of differences between the critical volumes of the various solvents.
Note: Similar mixing rules have been suggested in the literature for example, in:
J.M. Prausnitz, R.N. Lichtenthaler, de Azevedo E.G.,
'Molecular Thermodynamics of Fluid Phase Equilibria',
2nd ed., Englewood Cliffs (1986).
Keywords: gas solubility
Henry's law
Henry's constant
mixed solvent
option code
References: None |
Problem Statement: Model Library is not visible anymore in the Aspen Plus Graphical User Interface. | Solution: First go through the points 1 to 4. If this does not help, proceed with points 5 to 14. The second part should only be done with the help of IS and after having made a backup of the current registry settings.
Load a simulation in Aspen Plus, go to View/Model Library, and UN-CHECK the Model Library.
Go back to View/Model Library and CHECK it.
Check at the corners of the computer screen for the model library. It might be hidden somewhere such as at the bottom under the Start Menu Bar. Move the item away if it is blocking the Model Library!
If you see the Model Library, move it onto Aspen Plus, right mouse click on the model library and select ALLOW DOCKING, then dock it at the bottom of Aspen Plus.
If this does not help, then continue with the steps below. Before starting this second part, consult with an IS person and ask the IS person to proceed with this! In addition, make a backup copy of the registry before proceeding.
Uninstall Aspen Plus
Go to Start --> Run
Type in regedit and hit OK.
Within the registry editor, go to HKEY_LOCAL_MACHINE\SOFTWARE\AspenTech\Aspen Plus\10.2
If the folder does not exist, then the uninstall worked correctly for this part.
If the folder exists, Right click on the 10.2 folder and select Delete.
Next:
Within the registry editor, go to HKEY_CURRENT_USER\Software\AspenTech\ASPEN PLUS\10.2
If the folder does not exist, then the uninstall worked correctly for this part.
If the folder exists, Right click on the 10.2 folder and select Delete.
Reinstall Aspen
Keywords: Model Library
References: None |
Problem Statement: When does it help to have multiple sets of generated pseudo components? | Solution: By default, Aspen Plus generates only one set of pseudocomponents to represent all of the streams. Sometimes, when the assays are VERY DIFFERENT (i.e. one is very paraffinic and another is very aromatic), even increasing the number of cut points won''t improve the curve fit to adequately handle the very different densities of the different assays.
In the attached example, ONE-SET.bkp, a single set of pseudocomponents is used to model two different assays. Although the two have similar distillation curves, one has a bulk API gravity of 16 and the other has an API gravity of 34. When a single set of pseudocomponents is allowed to model both streams, the density curve fit is terrible, with both streams reporting an API gravity between 23 and 25.
In the other attached example, TWO-SET.bkp, one set of pseudocomponents is generated for each of the two assays. The procedure for this is described in the next paragraph. In this example, the densities/API gravities are very accurately reproduced - the input value equals the calculated value on the stream results.
To create two sets of pseudocomponents, go to Compopents \ Petro Characterization \ Generation, and create two objects (G-1 and G-2 by default). In the first object, select the first assay (and other assays which are similar in boiling range and density) on the Specification form. Proceed to the second object and select the second assay (and others that are similar in boiling range and density).
You may want to name the pseudocoments in the two set differently so that in the stream report they can be differentiated. This can be done on the Naming Options sheet. Select User defined list and provide a name for each cut.
Keywords: petro
petroleium
ada
assay
pseudo
pseudocomponent
generation
multiple set
References: None |
Problem Statement: There are some important issues in raising a variable to a power, like for example in power law kinetics. For example, let's assume that we have a reaction:
A --> B
where the reaction rate is given by:
r = k0*CA^alpha
k0 is the reaction constant, CA the concentration of A, and alpha the reaction order. Assume that alpha is 0.5, ie a fractional reaction order.
If the concentration of A decreases (which is likely as it is the reactant), we risk taking the power of zero or a small number. So it is important that the lower bound of A is set to 0. You could try setting the lower bound to a small value, like 1e-10, but this means that the simulation may not converge if effectively all A is consumed by the reaction.
It is probably better to use another expression for the reaction rate. | Solution: The following expression should give very accurate results, and prevent the problem at low concentrations:
r = k0*CA*(CA+epsilon)^(alpha -1)
where epsilon is a real parameter, set to a small value. This means that if CA becomes smaller than epsilon, the reaction rate will be quasi-linear, thus giving better properties to the equation (a finite derivative at 0 instead of an infinite derivative.)
Keywords: None
References: None |
Problem Statement: None of the pseudocomponents generated are shown on the SEP2 block input form. How do you access these components in a block or in a design specification or in a reaction? | Solution: Pseudocomponents generated automatically from an assay in Aspen Plus using the default naming convention (such as PC125) will not shown on the SEP2 block input forms. In fact they don't show in any block input form, including SEP and all reactors. This is by design, not a bug.
To generate the list of pseudocomponents to show on the input forms,
1. Go to the Components \ Petro Characterization \ Generation object manager.
2. Create a new ID.
3. On the Specification sheet, enter the Assay or Blend ID.
4. On the Naming Options sheet, check the Generate Pseudocomp Name box. Any naming convention can be used.
Keywords: petroleum
ada
pseudo
pseudocomponent
naming
SEP
SEP2
reactor
generation
References: None |
Problem Statement: How do I enter the tube bundle layout using the input forms or the graphical interface in Aspen Air Cooled Exchanger (Acol+)? | Solution: Aspen Air Cooled Exchanger (Acol+) permits symmetrical and non-symmetrical bundles to be entered, depending upon the data items that have been specified on the Input | Exchanger Geometry | Geometry Summary | Geometry tab.
Symmetrical bundles will have the same number of rows per pass, whereas non-symmetrical bundles may not. The attached Word document describes how symmetrical or non-symmetrical bundles may be set up. Also the option of using a Number of circuits is described where repeats of the pass layouts specified are used a number of time across the bundle.
Keywords: bundle specification, symmetric, non-symmetric (asymmetric), tube layout, tube pass
References: None |
Problem Statement: How do I display cumulative heat load specification instead of specific enthalpy in properties? | Solution: The new cumulative heat load option will allow users to specify a cumulative heat load versus temperature profile for a stream rather than use specific enthalpy data. This option can be selected from the pull down list for the physical property package as shown below. When selected an additional input field will appear to allow the user to specify a reference flow rate for the heat load to be specified. In this way, the program will be able to adjust the heat load for the stream if the process flow rate should be different than that of the reference flow.
Once selected, the physical property input screen will be displayed, showing cumulative heat load rather than specific enthalpy. When the heat load option is selected, the user must specify all pertinent physical properties and the pressure levels are restricted to a single pressure level.
Keywords: Cumulative heat load, specific enthalpy, user properties etc;
References: None |
Problem Statement: Which variable values are used for the dead_time block during the initialization by the solver? Dead_Time block uses the DELAY operator. | Solution: For initialization and steady state runs:
Delay does not apply, i.e. the equation y = DELAY x BY dt; is solved as if it was written y = x.
For dynamic runs:
The delay leaves the output (y) equal to the value of the converged initialization run at time 0 (x(0)) until the time is equal to the specified dead time (dt). At that point, it starts playing back the delayed values.
Keywords:
References: None |
Problem Statement: I am going to customise an Aspen Dynamics problem but I see unmatched variables when loading the Aspen Dynamics file in Aspen Custom Modeler. I have not made any changes to the file but I do not see this message when loading the same file in Aspen Dynamics.
Why does this happen and what does it mean? Will my results be different?
Here is an example of what appears in the Simualtion Messages window in 11.1:
Warnings raised when updating STREAMS(BOTTOMS):
processing connection between BLOCKS(COLUMN).Out_B and STREAMS(BOTTOMS).In_F,
the following variables don't match
STREAMS(BOTTOMS).In_F.Avrev
STREAMS(BOTTOMS).In_F.hrev
STREAMS(BOTTOMS).In_F.Slip
STREAMS(BOTTOMS).In_F.Trev
STREAMS(BOTTOMS).In_F.Zrev(MCH)
STREAMS(BOTTOMS).In_F.Zrev(PHENOL)
STREAMS(BOTTOMS).In_F.Zrev(TOLUENE)
In 10.2 ther is only one unmatched variable:
STREAMS(BOTTOMS).In_F.Slip | Solution: The results of the unchanged file will be exactly the same.
Slip is used in pressure relief calculations so in pipe, RCSTR, and the pressure relief models. It will only be something other than 1.0 if two phase, non-homogeneous flow is being modelled i.e. the vapour and liquid velocities are different.
It is also used in Traflow.
The other variables containing rev in their name are variables used for reverse flow in 11.1.
Since these variables are only used in certain circumstances, they are not active in many cases and are therefore unmatched.
The reason why you see the messages when loading the file in Aspen Custom Modeler and not when the same file is loaded in Aspen Dynamics has to do with the settings in each software. If you go to the Tools Menu, Settings, Preferences tab, you will see an item on Warn on mismatched variables on port connect. This is not ticked in Aspen Dynamics, but it is ticked in Aspen Custom Modeler by default. That is why you do not see the warning on Aspen Dynamics but you do in Aspen Custom Modeler. Apart from that, the behaviour in terms of convergence will be exactly the same and you can safely ignore the warnings.
Keywords:
References: None |
Problem Statement: How do you embed a double quote in a string in Visual Basic/VBscript? | Solution: To embed in a string, you need to use double double quotes, e.g. Fmc(H2O) instead of Fmc(H2O).
Keywords:
References: None |
Problem Statement: Results for the condenser temperature differ between PetroFrac and RadFrac if the condenser is subcooled. | Solution: The results are correct, the difference in condenser temperature is due to a reporting convention.
In the attached example file, both the PetroFrac and the RadFrac blocks are set up in the same way, including the option both reflux and liquid distillate are subcooled.
The reported results for the column are the same, with the exception of the reported condenser temperature: All the stage flows, the temperatures for all stages other than stage 1, and the condenser duty are equal. There is difference in reporting the temperature on stage 1. The actual condensing temperature can be seen in both cases from the temperature reported for the distillate stream. This is the temperature reported for stage 1 in the PetroFrac column.
Note that there is another difference, in the convention to report the molar stage flows. As pointed out in the report (.REP) file for RadFrac
REPORTED VALUES FOR STAGE LIQUID AND VAPOR RATES ARE THE FLOWS FROM THE STAGE EXCLUDING ANY SIDE PRODUCT. FOR THE FIRST STAGE, THE REPORTED VAPOR FLOW IS THE VAPOR DISTILLATE FLOW. FOR THE LAST STAGE, THE REPORTED LIQUID FLOW IS THE LIQUID BOTTOMS FLOW.
while for PetroFrac the stage liquid flow is the net flow that goes to the lower stage.
Keywords:
References: None |
Problem Statement: In the Decanter block, how is the specified separation efficiency of each compoent used? | Solution: In the decanter block, the specified component separation efficiency (Ei) is used as follows
x2i = Ei Ki x1i
Where E = specified component separation efficiency
K = equilibrium constant
x1 = liquid 1 mole fraction
x2 = liquid 2 mole fraction
i = component i
Ei is a fudge factor. It allows a user to manipulate the equilibrium results.
When the efficiency field is left blank, Ei = 1.0.
Varying the efficiency of one component affects not only the separation of that component, but also the entire system.
Specifying unrealistic Ei may cause equilibrium calculation to fail.
There are two ways to determine phase split:
equating component fugacities of two liquids
minimizing Gibbs engergy of system
When B is selected, the efficiency tab will be grayed out and valid phases = liquid-Freewater is not allowed.
The online help (efficiency field help) states:
Decanter outlet streams are normally at equilibrium. However, you can specify separation efficiencies on the Decanter / Input / Efficiency sheet to account for departure from equilibrium. If you select Liquid-FreeWater for Valid Phases on the Input CalculationOptions sheet, you cannot specify separation efficiencies.
which is not clear and accurate.
Keywords: decanter
efficiency
separation efficiency
liquid-liquid
liquid-freewater
equilibrium
References: None |
Problem Statement: For processes involving many unit operations it is sometimes desirable to specify different property methods for use in individual sections of the flowsheet. However, calculating the physical properties of the very same system by means of different property methods can lead to different results. This may result in a discontinuity when passing stream properties from one flowsheet section to another. | Solution: The reason for the discontinuity is that different property methods define different models and routes for a given property such as the enthalpy of the liquid phase. An activity coefficient model for example, typically calculates the liquid phase enthalpy (HL) in the following way
HL = HIG + DHV + DHVL
where
HIG : ideal gas enthalpy
DHV : vapor pure component enthalpy departure
DHVL : pure component enthalpy of vaporization
while an equation of state uses another approach:
HL = HIG + DHV + DHL
where
DHV : vapor pure component enthalpy departure
DHL : liquid pure component enthalpy departure
(See Physical Property Methods and Models
Keywords: Discontinuous Physical Properties
Property Models and Routes
Flowsheet Sections
HEATER block
References: Manual, Chapter 4, for further details on property calculation methods and routes.)
If the goal is simply to overcome the discontinuity, a Heater block can be inserted at the interface of two flowsheet sections. The Heater block is an ideal unit to handle the discontinuity because
it calculates stream properties according to the selected combination of state variables (temperature, pressure, vapor fraction and heat duty) and
a stream can be passed through a Heater without being separated because unlike the 2-phase or 3-phase flash blocks (Flash2 and Flash3 respectively), a Heater does not perform phase separation.
Note: If the goal is to make the results of different property methods match, you will have to adjust the model parameters by means of data regression (see Document 104115). |
Problem Statement: See the attached file for an example in Aspen Plus V7.3. The feed stream is made of water, NH3, HNO3 at 1 bar and 165C. This stream goes into a Flash2 block specified with a pressure drop of 0 and a heat duty of 0.
The simulation fails for both the feed stream enthalpy calculations and the block. Why? | Solution: This is a known problem. If you have a vapor phase stream and try to solve as a vapor-liquid (V-L) problem using apparent components, the chemical equilibrium calculation code does not behave well. This is somewhat true for true-component approach also. For the feed stream, we suggest to change the valid phase option as Vapor-Only on the Flash options tab (or NPHASE=1 and PHASE=V in input language syntax). For the case of the Flash2 block, it should be replaced by a Heater block. Note that if you specify conditions which will lead to formation of the liquid phase, the Flash2 block should work correctly. We are not able to fix this limitation as it would require dramatic changes to the way apparent components approach works.
Keywords: None
References: None |
Problem Statement: Customer is unable to start the License manager on the PC. The NT Event Log will display an error stating Unable to find Host Lock. No error will be displayed on Windows 95/98. This typically happens after the License Manager has been configured and running properly for some period of time. | Solution: The SuperPro dongles has failed and will not allow the License Manager software to start properly. There were a faulty series of SuperPro dongles shipped to AspenTech last year, which may fail with no notice.
In order to minimize down time, perform the steps below:
Verify that the dongle is attached to the parallel port.
Verify the parallel port BIOS settings. The ideal setting is ECP or Uni-Directional.
Run the utility ~\Program Files\AspenTech\License Manager 2.0-2\SuperPro\Find32.exe. This utility will search for the dongle. Open the utility and select the Find Keys button. If the utility locates the SuperPro dongle, the SuperPro check box in the Keys Found column will be highlighted.
If the Find32.exe utility does not locate the dongle, submit a request to Order Administration for a replacement dongle. Provide Sales Order and shipping address, to insure quick delivery of the replacement dongle.
Keywords:
References: None |
Problem Statement: Is it possible to use a Design-Spec from Sequential Modular (SM) mode in Equation Orientated (EO) mode?
The Design Specification is executed in SM mode, and the result is used to initialize the problem in EO mode, but the target value is not kept when changes are made in the EO problem. Is it possible to keep the target fixed? Is there another way to simulate a feedback controller? | Solution: Flowsheet design specifications are not supported in EO mode. Instead, a Spec Group must be used to make the equivalent variable specification changes in EO. Design specifications internal to a RadFrac block are supported and are carried over to EO; Spec Groups do not need to be created for them.
In EO mode, the variable specifications can be changed directly on the EO Input forms. This is mostly done through Spec Groups. When Aspen Plus initializes EO from an SM simulation, the change in variable specifications from a Design-spec (SM) are not translated to EO mode. Therefore, a Spec Group must be used to make the equivalent variable specification changes in EO.
Spec Groups in EO are actually more limiting than Design Specifications since only one variable can be can be varied and only one can be set whereas in a Design Specification, the target can be any Fortran expression and can be dependent on any number of variables. If a complex target expression is needed, this expression can be written using a Calculator block.
For example in the attatchment, there is a design specification to vary the cool block temperature to achieve a cumene purity of 92% in the PRODUCT stream. The steps to move a Design-spec from Sequential Modular (SM) mode into a Spec Group in Equation Orientated (EO) mode are as follows:
Complete and run the SM simulation.
Open the Control Panel, and click the More button at the bottom of the window to display the EO controls.
In theSolution Stategy list, change Sequential Modular to Equation Orientated, which will initialize the EO variable values from the SMSolution. This step is called synchronization. The Control Panel will indicate when this synchronization is complete.
In the Data/EO Configuration/Spec Group form, type in a name for the new Spec Group you wish to design. Highlight the Spec Group and select Edit, which will open the Define Spec Group form. In this form, define ALL the variables to be used in the Spec Group including both those that will be varied and those that will be specified.
Click in the List of variables field, and a button will appear at the end of the field. This button opens the EO Variables Finder dialog box.
Select those Variables which are required in the Spec Group and change the User Spec accordingly. Using the example in the attachment, the variable for the COOL block temperature: COOL.BLK.COOL-OUT_TEMP is initially specified as CONSTANT from the SMSolution, since the temperature of the block was specified. In the Spec Group, the specification will be changed to CALCULATED (ie. varied). The variable for the cumene mole purity in the PRODUCT stream: SEP.BLK.PRODUCT_CUMENE is initially specified as CALCULATED from the SMSolution. As we now want to specify a value of 92% to this variable, in the Spec Group, the specification is changed to CONSTANT. Refer to the file: Define Spec Group.bmp for illustration.
It is very important that specification changes are always made in pairs, this is referred to as Spec Swapping:
Before
After
variableid1
Calculated
--------->
Constant
variableid2
Constant
---------->
Calculated
In this way, the problem remains square (net specification of problem is zero) and aSolution can be calculated. If the net specification is greater than zero, the the problem is underspecified and has manySolutions. Conversly, if the net specification is greater than zero, then the problem is overspecified and has noSolution.
In the Data/EO Configuration/EO Input form, the variable which was set as CONSTANT in the Define Spec Group form is given a target value. In our example, the variable cumene purity is given a value of 92(%). Refer to file: EO Input.bmp for illustration. Again, clicking in the variable field on this form will show the button that links to the EO Variables Finder dialog box.
The Spec Group is now complete and equivalent to a design specification in EO mode.
Run the EO simulation.
Note: In Aspen Plus 12.1, these steps will not be necessary if Use perturbation layer around closed model is selected on the Design Spec \ Input \ EO Options sheet.
Keywords: Spec Group
spec group
EO mode
Design Spec
design spec
References: None |
Problem Statement: I am installing AES 10.2 Update 1. Do I need to install new license key codes for these products? | Solution: Any keys that worked for any of the AES 10.2 products will work for the AES 10.2 Update 1 products. This also means that Batch Plus 2.1 keys will work for Batch Plus 2.2, and Aspen B-JAC 10.2 keys will work for Aspen B-JAC 10.3 (this includes Aspen Hetran, Aspen Aerotran, and Aspen Teams).
Keywords: keycodes keys apsen license manager alm
References: None |
Problem Statement: The current AZ Vessel Tray datasheet template is not configured for the overspill function. | Solution: You can download from thisSolution document a similar version of this template which can be overspilled.
1. Copy the attached xls file in the Datasheets directory of the Workspace library (e.g. C:\AspenZyqadServer\Basic Engineering16.2\WorkspaceLibraries\Datasheets).
2. Copy the attached ztf and ztx in the Templates directory of the Workspace library (e.g. C:\AspenZyqadServer\Basic Engineering16.2\WorkspaceLibraries\Templates).
3. In the Excel Datasheet Editor, open a Pressure Vessel datasheet for the Vessel Object (Datasheet=> Open Datasheet By Object) and select the function Datasheet=>Pages=>Insert. From the list of available templates, select the template AZ Vessel Tray Overspill.
4. By default, the first Vessel section object will be displayed on the tray datasheet. You can enter a Vessel Section number on the line 13. But if you want to display another Vessel section object, you need to use the function Datasheet=>Field=>Object=>Hide and then Datasheet=>Field=>Object=>Show.
5. You can enter on this page data for 4 trays.
6. If you want to specify data for additional trays, you can use the function Datasheet=>Overspill. This will create an additional page where you will be able to create or display additional trays.
Keywords: Datasheet
Tray
Overspill
References: None |
Problem Statement: How to use Microsoft Visual Studio debugger to debug user procedures or SAX function when these are called by ACM? | Solution: Note: The instructions are for Visual Studio 6.0 sp4. You need to install the service pack 4 (or above) of Visual Studio to fix a defect (see Microsoft Knowledge Base Article - 235434 FIX: Attach to Process List Is Empty, http://support.microsoft.com/default.aspx?scid=kb;en-us;235434).
The steps are:
build the DLL with debug options
start ACM (no need to open you simulation file)
in Tools, Settings, Debug, tick the option Debug User code
close ACM (this is to make the change in step 3 effective)
start ACM and open your simulation file (don't run it)
start Visual Studio (no need to open a new workspace)
in Visual Studio, go to Build, Debug, Attach to Process
select sim_server.exe
in Project, Settings, under Debug, category Additional DLLs select your DLL
open the source code, put the breakpoints where needed
go back to ACM and run
if you close ACM, the debug will stop. Save (*.opt) if you wish to do other debugging sessions (you can then skip the steps 9 and 10).
It should stop where you put the break points. Screen captures are printed in the attached word document. A EDI example on which I've tested the procedure above (with 11.1sp1). (EDI is the emulation of SPEEDUP EDI for SAX.)
You need to do steps 2-3-4 only once. This removes the exception handling around user code. Once you no longer want to debug, disable the option Debug User Code, as if errors occur in user code, this should give better error messages.
We will include the instructions for debugging procedures in the on-line help for version 12. In version 12, you will also get a notice in step 3 to remind you need to close and restart ACM to make the change effective.
Keywords:
References: None |
Problem Statement: When a SM (sequential modular) simulation is synchronised in Equation Orientated (EO) mode, there is no EO variable assigned for the component mole flow in a stream or block. What if you need to use this variable? | Solution: If you need to access a component mole flow to use in a Spec Group for example, then the component mole flow must first be calculated in a Calculator block, so that an EO variable is created for it. This example shows how to calculate a component mole flow in Equation Orientated (EO) mode.
For example in the attachment, EO Molar Flow.bkp, the product Ethanol mole flow (in stream P-STOIC) is needed for use in a Spec Group. The steps to do this are as follows:
Complete and run the SM simulation.
Open the Control Panel, and click the More button at the bottom of the window to display the EO controls.
In theSolution Stategy list, change Sequential Modular to Equation Orientated, which will initialise the EO variable values from the SMSolution. This step is called synchronization and the Control Panel will indicate when this synchronization is complete.
Open the Data/Flowsheeting Options/Calculator form. In the Object Manager create a new entry, in the example the calculator block is called MOLEFLOW.
In the Calculator definition form, define all the variables to be imported and exported from the calculator block. The variable to be calculated (exported) for the component mole flow, named MOLE in the example, must be defined as a catagory MODEL UTILITY and type PARAMETER as illustrated in file: Parameter.bmp. It is recommended not to use the component mole flow as an export variable here. Use a PARAMETER as an export variable instead as this avoids overwriting the component mole flow calculated internally by Aspen Plus.
When defining the import variables, be sure to connect the EO variable in the Open variable field of the define variable wizard. Refer to file: Input variable.bmp for illustration.
Reinitialize the Equation Orientated (EO) simulation to build the exported EO variable(s) from the Calculator block. In this example, the EO Ethanol mole flow from Calculator block MOLEFLOW is defined as: MOLEFLOW.BLK.PARAMETER_1. This is the EO variable which must then be accessed in the Spec Group and EO Input forms.
Keywords: mole flow
EO mole flow
EO mode
component mole flow
References: None |
Problem Statement: What property method is used for a pure water stream? Will the free water property method be used?
In PML, a block (or stream) with the single component of water would use the free water method to calculate water properties, regardless of the primary property method. This behavior is not the case for Aspen Plus. | Solution: The primary property method is used for the stream properties unless free water is selected. If free water is selected, then the free water property method is used. See the attached simu1.bkp. Enthalpy balance and values remain identical either for water as the only non-zero component in three-component mixture, or for water as an only component of a stream.
In the attached test file there are three blocks:
Block ID
Description
B1
Uses SRK with Steam Tables and all three components
B2
Uses SRK with Steam Tables and water only
B3
Uses Stream Tables and water only
If you run this problem without free water, you get:
Block ID
Enthalpy (H) at 1500 psi
B1
-102.658 at 592.9 F
B2
-102.589 at 592.9 F
B3
-102.623 at 596.2 F
Clearly, each block is using the primary property method for its properties: the first two blocks are using SRK and the last is using the steam tables.
If you run this problem with free water, you get:
Block ID
Enthalpy (H) at 1500 psi
B1
-102.623 at 596.2 F
B2
-102.623 at 596.2 F
B3
-102.623 at 596.2 F
Now, all three blocks are using Steam Tables since the system is aware of it being water-only.
Moreover, Sequential Modular (SM) and Equation-Oriented (EO) agree completely in each case.
Keywords: free-water
References: None |
Problem Statement: When using Aspen Air Cooled Exchanger, users are given freedom to define fouling inputs for both tubeside (process side) and outside (X-side), especially for tubeside where there are multiple options. | Solution: The default method to input fouling factors is to type in a constant value directly, on Input | problem Definition | Process Data | Tube Side Stream tab for tubeside, and Input | problem Definition | Process Data | Outside Stream tab for X-side.
Besides this method, tubeside fouling can also be defined by going to Input | problem Definition | Process Data | Tube Side Fouling tab, where users have multiple choices to decide as a function of which parameter(s) the fouling factor values will be or determined, as shown below.
The options include:
? Thermal Conductivity & Thickness
Default Curve(s)
Function of Velocity
Function of Temperatures
Function of Quality
Function of Tube Length
Function of Stream Phase(s)
For the ''Default Curves'' option, 4 types of industrially treated water usages will be presented as 4 different curves, as shown below, where the Y-axis means the fouling resistance and the X-axis is velocity in terms of ''m/s''.
The treatments are:
(1) Zinc polyphosphate.
(2) Zinc phosphates, or zinc polyphosphates with organic polymers.
(3) Zinc phosphates with acids or similar treatment.
(4) Extended phosphate treatment, usually a mixture of orthophosphates, polyphosphates, phosphonates, polymers and acid treatment.
For ''Velocity'' ''Temperature'' ''Quality'' ''Length'' options, users must specify all the 3 values of the parameter and 3 corresponding values of the fouling resistance. Air Cooled Exchanger will carry out a linear interpolation between two of the points to get the resistance at each local condition.
For ''Stream Phase'' option, users need to input the resistance for each phase which the fluid can be in (i.e. liquid, 2-phase and/or vapour).
For Outside Fouling, on Input | problem Definition | Process Data | Outside Stream tab users can determine the resistance by using Thermal Conductivity & Thickness. The local fouling resistance can be determined as
γ = L/λ
where L is the fouling thickness and λ is the thermal conductivity of the fouling material. This feature in Air Cooled Exchanger enables users to input up to two different fouling thickness values for the whole bundle.
Keywords: Fouling Factor, Resistance, Constant, Input, Definition, Function, Tube side, Process side, Outside, X-side
References: None |
Problem Statement: How to get rid of Run time error 429: ActiveX component can't create object? | Solution: This error occurs if there is a problem with registry. Cleaning up the registry and re-register HTFS+ should solve the problem.
You will need administrative privileges for this.
Clean up the registry:
Find BjactRegClean.exe file. It is under XEQ folder inside HTFS+ folder. The default path is
C:\Program Files\AspenTech\Aspen HTFS+ (version)\XEQ
Double click on BjacRegClean.exe || OK to the message || Search Registry || Cleanup || close the window.
Re-register HTFS+:
Find regcontrols.bat file in the same XEQ folder.
You just need to double click on this file.
After it registers, it will close without giving any message.
Keywords: Run time error 429, run time, error, 429, activeX component can't create object, activeX, ACOL, Acol+
References: None |
Problem Statement: How do I change the workspace name? | Solution: Lets say if you want to rename a AZ162 workspace to AZTest.
- Open Workspace folder and change the folder name from AZ162 to AZTest.
- Open Workspace.lst file under workspace folder and also change the name here from AZ162 to AZTest
- Restart the broker.
Keywords: Rename workspace, change name
References: None |
Problem Statement: How to write to journal file from KB script | Solution: The following code can be used to write to the journal file called journal.log. This file is located in the workspace directory on the ABE server (e.g C:\AspenZyqadServer\Basic Engineering16.2\Workspaces\AZ162).
server.logInformation (strMessage)
server.logWarning (strMessage)
server.logError (strMessage)
Keywords: Journal
KB Script
References: None |
Problem Statement: Sometime, a user created in-house library to use with ACM, and does not want to see the default libraries. How can one remove the default libraries from the ACM Explorer? | Solution: One can remove the default libraries for the ACM Explorer (for example, Modeler.acml) using the command line option /Nodefaultlibraries in Command Prompt. For example, you use command line:
C:>C:\Program Files\AspenTech\Aspen Custom Modeler V7.1\acm.exe /Nodefaultlibraries
This option is first available in version 12.1. Care should be taken not to remove libraries which are being used; otherwise you will get errors on reloading the simulation.
Keywords: default libraries
References: None |
Problem Statement: A simulation uses procedures calling external Fortran code. The external code is reading data from file(s). The dll is created successfully and all the procedures are correctly defined. The code has also been tested separately and is running properly.
When running the simulation the following error can occur:
One of the application serves has failed.
This could be due to user supplied external code:
You should save your work, then the application will shut down. | Solution: Below is an identified cause. If it does not apply to your specific case, please contact Customer Support and include the files, if possible, to help us troubleshoot the new problem..
If the OPEN FORTRAN statement that is defined in the external code does not have the full path to where the file(s) containing data to be read is/are located, Aspen Custom Modeler cannot find the file(s) and could fail with the message above. In this case ensure that the file(s) containing data to be read by the external code is/are placed in the folder with the same name as your problem located in the current default Working Folder.
You can find out where is your current working folder by going to the File Menu and selecting Set Working Folder...
Keywords:
References: None |
Problem Statement: What components of an air-cooled exchanger are included in a reported 'weight of exchanger' in Aspen Air Cooled Exchanger? | Solution: The weight parts such as support structure and fans are not included as the data on these are not available in Aspen Air Cooled Exchanger. The results of the calculations are in the form of two weights: Total weight of an empty tube bundle(s) and weight for tube bundle(S) filled with water.
The following description identifies how Aspen Air Cooled Exchanger estimates the weight of the exchanger bundle
1. No U-bends case: for exchangers with bare tubes, with high fins, low fins, plate pins, or studs the total weight of an empty bundle is the sum of components (a-d) below
a. Headers, inlet & other including tube sheet. The following assumptions have been made:
i. Use same weight calculations for Box, Plug or Cover-Plate headers. Weights of D-headers and Manifold headers are calculated each separately.
ii. Minimum thickness of header components will be as recommended by API 661, April 1992.
iii. As location of nozzles is not important to weight calculations and for simplicity, as inlet nozzles are on inlet header on top side and outlet nozzles are on the other header bottom side.
iv. Ignore pass & perforated plates.
v. For inlet header, tube sheet is always on left-hand side. For other header on right hand-side.
b. Tubes (bare)
c. Fins or stud-first and second type (if used) or plate fins. Assume all types of fins are round
d. Nozzles: length of nozzle assumed as 1.5 I.D. Nozzle pipe minimum wall thickness follows section 4.19.5 of API 661 April 1992. Calculation of flanges volume follows HTFS DR12 (As in Aspen Shell & Tube Thermal). The Tube side design pressure and temperature required in these calculations will be 20%> than operating pressure and temperature input to Acol+. Nozzle material same as header material.
e. Side frames: Assume channel shape as shown in picture below, wall thickness of 6 mm and material as Carbon Steel. The minor dimensions in a cross section of channel are assumed to be 100 mm wide.
f. Tube supports: Assume wall thickness of 1 mm and material as Carbon stell. Spacing is 1.8m (Ref: section 4.1.4 of API 661 (1992). See picture below.
2. U-bend in alternate passes: calculate number of U-bend and weight based on equivalent length
3. U-bend in every pass: same as (2) above but weight of other header is included. Width and length of inlet and other headers are calculated from geometry details of first and last passes respectively.
Keywords: Weight, Bundle weight, unit weight.
References: None |
Problem Statement: I get an error AirCooled (Input Error 524) the total outside stream mass flow must be input. What to do about this error? | Solution: The error message indicates that the air flow rate is missing. HYSYS displays the error after importing AirCooled / Aspen Air Cooled Exchanger / Acol+ file into HYSYS air cooler.
Double click on the air cooler. Go to Ratings tab and input the flow rate of air. If you don't know it and you have it in the AirCooled file. Open the file in standalone AirCooled, get the air flow rate and input in HYSYS air cooler's Rating tab.
HYSYS imports only geometry information for aircooler from AirCooled / Acol+. Process stream and properties data is calculated / specified within HYSYS. As there is no air inlet stream attached to the air cooler, user would need to enter the air flow rate inside the air cooler model.
Keywords: Input error 524, total outside mass flow must be input
References: None |
Problem Statement: What is the user privilege needed when importing a Simulation | Solution: The privilege Modify_Process_Data or TrespassDiscipline is needed when importing a simulation. The reason is that the Process discipline is assigned to attributes used by the simulator interface. If the user doesn't have one of these privileges, the simulator interface will not be able to import the simulation.
Keywords: Discipline
Process
Simulator Interface
References: None |
Problem Statement: How do I access simulation time in the model? | Solution: The model shown below illstrates the syntax.
Model TimeModel
TimeValue as time_;
x as realvariable;
TimeValue = time;
IF TimeValue < 0.01
THEN x = 1;
ELSE x = 2;
ENDIF
End
Keywords:
References: None |
Problem Statement: Why does CDI issue the error message The Index of your model is >1, for example if I try a CDI after a steady state run of an Aspen Dynamics simulation? | Solution: The CDI test for index>1 is different from what the Analyse tool does. So they can sometimes come to a different conclusion.
If your simulation has an index>1, this is detected in version 11.1 when you use the View, Specification Status. There is a button Check Legality/Index. This is not available in previous versions. No version of ACM has an integrator that can reliably handle system of index>1. You need to modify your model or specification. SeeSolution http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=3023 for a description on index and some actions that can be taken.Solution http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=102886 explains how to detect index>1 in versions before 11.1.
The index of a differential-algebraic system (DAE) is defined as the number of times you need to differentiate some or all of the equations before you can determine the time derivatives of all variables from their values.
The state space form has an index of 1:
dx/dt = A.x + B.u
y = C.x + D.u
One differenciation is required to obtain dy/dt and du/dt. du/dt = 0, as u are fixed.
dy/dt = C.dx/dt = C.(A x + B u)
As one round of differentiation has been required, the index is 1.
By definition, CDI is not possible for a system of index>1, because this would imply that some state variables are undeterminated.
The problem with CDI after a steady state run can be caused by code like this:
solmode as notype;
vcum as realvariable (initial);
Call (SolMode) = pSolMode ();
IF (Abs(SolMode-1.0)<1E-5) Then // Steady state
Vcum = 0 ;
ELSE // Not steady state
$Vcum = x;
ENDIF
which is used in the Rstoic model when using the PFR mode (see Submodels, ReactorBase). CDI flags Vcum as a state variable, because an equation uses its derivative. However, the equation $Vcum = x is not active for the steady state run, so that causes the index>1 problem. Numerically, there is nothing wrong in the steady state run, and no index>1 in the initialization/dynamic run.
A CDI run in steady state run mode causes error messages like this:
CDI summary of matrices computed:
A matrix requested but unavailable due to error:
The Index of your model is >1 B matrix requested but unavailable due to error:
The Index of your model is >1 C matrix requested but unavailable due to error:
The Index of your model is >1 D matrix requested but unavailable due to error:
The Index of your model is >1
TheSolution is to do the CDI calculation with initialization run mode instead of steady state run mode.
Another way of resolving this problem is to change the equations to:
IF (Abs(SolMode-1.0)<1E-5) Then // Steady state
$Vcum = -Vcum;
ELSE // Not steady state
$Vcum = x;
ENDIF
This leads to the sameSolution of Vcum = 0 for steady state, but keeps Vcum as a state variable regardless of the run mode.
A similar problem could occur if you have some run time conditions with algebraic equations in one branch and differential equation in the other. This is a hidden index problem, i.e. the analyze tool does not detect it, and with the expection of the example above, this is not a correct modelling approach.
You need also to remove any indeterminate variable, switch tearing off. Note that the DELAY are ignored, i.e. y = delay x by t is just as if it was y = x. In any case, delay does not fit in state space form.
Keywords: CDI
References: None |
Problem Statement: In Shell & Tube Exchanger, users can model a re-flux condenser by selecting 'Knockback reflux' as the Condenser type on Input | Problem Definition | Application Options | Application Options tab. In Air Cooled Exchanger (Acol+), there is no such option. Is it possible to model a reflux condenser within Air Cooled Exchanger? | Solution: If you have an Air Cooled Exchanger case with tubeside condensing, and you want to model a re-flux air cooled condenser, you need to
? go to Input Exchanger Geometry | Unit Geometry | Unit Geometry tab
? Set 'Angle of outside flow' as an angle other than either 0 or 180 degrees ( 0 means the outside flow is vertically upward and 180 means vertically downward. As the program always assumes the outside and tubeside flows are perpendicular to each other, a 0 or 180 degree outside flow means the tubeside flow is horizontal. A 90 degree outside flow means the X-side flow is horizontal, so the tubes are vertical.)
? set 'Tube side flow direction' as 'Upward (any angle)'
After entering other geometry information, the process and property data, run the case, where the results will take into account the re-flux condensing considerations.
However, there are 3 issues that users need to be aware of:
? When you model re-flux condensing in Air Cooled Exchanger, you need to be careful with any warnings regarding flooding velocities.
? There are no input options for using separate tubeside outlet nozzles for liquid/vapor flows.
? Results | Calculation Details | Interval Analysis - Tube Sides | Interval Analysis tab shows the liquid/vapour flows, temperatures and heat transfer coefficients etc along the length of the tubes. This is presented for a co-current flow where the liquid and vapour phases are flowing in the same direction hence the liquid and vapour flows shown are the cumulative (total) flow at the position in the tube, based on the heat transfer area.
For a reflux condenser, the liquid flows back down the tube, under gravity, against the vapour flow (counter-current). For the Interval Analysis along the tube, the liquid flow difference between every two points shall be interpreted as the amount of liquid condensing in the zone.
For example, in the below screen shot, the condensing amount between 1449.5 mm and 1932.67 mm is (0.0002 kg/s - 0.0001 kg/s) = 0.0001 kg/s.
Keywords: Reflux, Knockback reflux, Re-flux, Air Cooled Exchanger, Acol+, Interval Analysis, Interval Analysis, Plots, local condensing amount, cumulative flow
References: None |
Problem Statement: Sometimes reloading a saved simulation fails to converge, while it was working properly before. Why? | Solution: This is because Aspen Custom Modeler and Aspen Dynamics do not automatically preserve the value of the variables (unless you have manually assigned values). Typically this results in free variables not being preset to a value close to theSolution, hence causing convergence failure.
The robust way to prevent this to happen is to use kept results.
To do this:
restart your simulation
change the run mode to Initialization or Steady State as appropriate
do a run (which should converge)
click on the Snapshot Management tool (ie the camera)
click on the Create sheet
enter a name in the Description field (ie start)
click again on the General sheet
select the snapshot you have created (ie start)
click on the Keep button
Now you have created a Kept Result with the value and specifications of all variables in the simulation at time 0.
Steps 2 and 3 can be skipped if the simulation was running correctly before you restarted it (ie you paused the simulation instead of interrupting).
Note that you can have manually created snapshots marked as kept results by default in Tools, Settings, Snapshot. (If so, you don't need steps 7, 8 and 9).
You can now save your file, where your results are now safely stored.
When opening the file, you can copy the saved results:
click on the Snapshot Management tool (ie the camera)
select the result you want to use
click on the Copy Values button
Note that Copy Values copies every variables (fixed, free, initial).
Important: snapshots and results do not contain the parameters.
You can use kept results to keep different starting points for a simulation in the same file. To repeat changes of parameters or variables (like for example settings of controllers), you could use scripts.
Note that kept results increase the size of your files, so it is a good idea to remove results when you are sure you no longer need them.
Why does a run initialize sometimes without going through these steps?
This is because ACM & AD maintain the binary snapshots (files with snp extension) in the working directory. If you have selected the option Load Latest Snapshot on opening this simulation, it will look in the simulation server working folder for the file snapshot.bak (which becomes snapshot.snp when the program is running) and use it (ie copy values) . If the file is not present (ie you have changed the name of the simulation or have copied the file on a different computer), then the variables will not be copied correctly, and the simulation may fail.
Keywords:
References: None |
Problem Statement: What is the difference between Aspen Air Cooled Exchanger program calculation modes? | Solution: Design with fixed outside flow
In design mode, you specify the performance requirements in terms of inlet and outlet process conditions. The program searches for a satisfactory heat exchanger configuration by varying the tubes per bundle, the tube rows deep, the tube length, the tube passes, the bundles per bay, the bays per unit and the fans per bay.
Design with varying outside flow
In design mode, you specify the performance requirements in terms of inlet and outlet process conditions on the tube side and the inlet temperature on the outside of the tubes. The program will vary the outside flow and determine the required outlet temperature for that flow. For each flow, the program searches for a satisfactory heat exchanger configuration by varying the tubes per bundle, the tube rows deep, the tube length, the tube passes, the bundles per bay, the bays per unit and the fans per bay. The final optimizedSolution will be selected based on capital cost of the equipment or the combined capital and operating cost. The user can control the flow and cost optimization using parameters located in the optimization options form.
Rating / Checking
In rating mode, you specify the performance requirements in terms of inlet and outlet process conditions and the specific heat exchanger configuration. The program checks to see if that heat exchanger is adequate to meet the required heat exchange and maximum pressure drop requirements.
Simulation
In simulation mode, you specify the specific heat exchanger configuration and some combination of stream process conditions. The program will predict one or more of the unknown conditions of the two streams. There are nine different simulation options for AirCooled.
Keywords: Design, Rating, Checking, simulation, Calculation modes etc;
References: None |
Problem Statement: How does CDI scale the elements of the matrices? | Solution: The value of the elements of the matrices are scaled using the units of measurement selected in the User InterfaceI.
Example:
x as flow_mol (initial);
y as temperature (free);
u as flow_mol (fixed);
$x = -x + u;
y = x;
gives C(1,1) = 1 if y is in degree C and x in kmol/hr, C(1,1) is 1.8 if y is in degree F and x in kmol/hr (1 K = 1.8 R). If x is in kmol/s, y in C, then C(1,1) = 3600 and finally if x is in kmol/s, y in F then C(1,1) = 6480.
Keywords:
References: None |
Problem Statement: When PFD is submitted, all the symbols and connections turn gray and line width is not retained. Is there an option to turn this feature off? | Solution: If you will turn off the emphasize flag from view menu, it will turn off the rea-donly flag on display. When you will submit/check/issue PFD, the PFD will retain the color and line width
Keywords: None
References: None |
Problem Statement: How do I create a Restricted Case? | Solution: It can only be created from Explorer for particular object.
Restricted cases are created against a particular object.
You can create it from explorer by following steps below:
Select object for which you want to create a restricted case in explorer
On toolbar click on Case | Create | Restricted
It will ask you for a name of restricted case.
Note: You will see this restricted case only against this object.
Keywords: restricted case, create restricted
References: None |
Problem Statement: Running a dynamic estimation - the simulation is very slow to run. | Solution: First of all make sure you review the advice outlined in this document:
Hints on using Optimization in Aspen Custom Modeler and Aspen Dynamics
You can improve performance further by choosing a communication interval with a value higher than the final dynamic simulation time for your experiments. This may speed the estimation run quite a bit by avoiding unnecessary communication between the simulation solver and task manager. The communication interval is not relevant in this case because the measured values in the dynamic experiments are transferred to the solver always at the time defined in the Estimation tool and you cannot access the variable values for viewing during the estimation run.
Note that if you switch to plain dynamic run, you will have to change the communication interval again, to a suitable value that will allow time changes to variables to be communicated to the simulation solver by the task manager.
Keywords:
References: None |
Problem Statement: In administrator tool, Drawing editor and Bridge privileges are missing and as a result existing drawing cannot be opened and new diagrams cannot be created. What is workaround? | Solution: This seems to be because of windows bug. A program was written as a diagnostic tool to understand the problem, that doesnt make any system changes. It does not update the registry but simply reads and prints. The process of printing out the contents of the category manager solves the problem on the machine. It is an *.exe file which is attached along. To run it:
1. Open a command window using Start/Run and type in cmd.
2. Use cd to change directory to the folder containing the*. exe.
3. Type name of exec e.g. if the exe file is save at C:\Downloads, it should be
C:\Downloads>EnumClassOfCategories.exe
Output:
This utility fixes problems described in CQ00354829:Aspen Basic Engineering: Multiple critical defects now confirmed on multiple machines
Usage:
EnumClassesOfCategories internalVersion
Where known internal versions are:
121 for 12.1
131 for 2004
141 for 2006
151 for 2006.5
161 for V7.0
162 for V7.1
165 for V7.2
171 for v8.0
After that write the version name e.g. for v 7.1 it should be 161
C:\Downloads>EnumClassOfCategories.exe 161
AZDBPackageSvcs.Main.161
AZDBPFDSvcs.Main.161
AZDBBridgeSvcs.Main.161
AZDBAuditSvcs.Main.161
AZDBTopologySvcs.Main.161
AZDBExplorerSvcs.Main.161
AZDBEFrameworkSvcs.Main.161
AZDBGenericSvcs.Main.161
AZDBDatasheetSvcs.Main.161
AZDBMappingSvcs.Main.161
This should fix the problem.
Keywords: None
References: None |
Problem Statement: Why is the setting plan for the air cooler missing in some cases? | Solution: In some cases, the setting plan will be unavailable as the Aspen Air Cooler provides a setting plan only for standard exchanger frame type air cooler. If an A or V frame air cooler is modelled, the setting plan for such type of exchanger will be missing.
Â
Keywords: Air Cooler, Setting Plan, Exchanger Type, Standard, A or V frame
References: None |
Problem Statement: Why don't I see the symbol relationships such as Equal, Parallel etc while defining symbol in graphic definer? | Solution: To enable a symbol to contain relationships, check the Tools | Maintain Relationships option in Graphic definer.
Keywords: Maintain Relationships , Parametric Symbols, Relationships
References: None |
Problem Statement: When comparing the results of the same case between Aspen ACOL 2004 (ACOL) and Aspen Acol+ (Acol+) the total X-side pressure drop and fan powers are quite different. | Solution: In Acol+ the correlation for the plenum pressure drop has been changed to that given in the book by Kroeger, D.G., Air Cooled Heat Exchangers and Cooling Towers New York, Begall House 1998. The previous method in ACOL, could in some circumstances, give a pressure loss in the plenum rather than a recovery (e.g., when the ratio of the fan/bundle area is small, say less than 0.3).
The plenum pressure drops are given in ACOL in the lineprinter output under the section X-Side Pressure Drops. In Acol+ the pressure drops are shown in Outside tab in the Results | Thermal / Hydraulic Summary | Pressure drop.
Keywords: plenum, fan pressure
References: None |
Problem Statement: What PDE methods are recommended for different modeling situations? | Solution: The following comments are meant as general advice - it is difficult to give advice for specific partial differential equation cases.
As you go from Central Finite Difference (FD) methods to Forward/Backward FDs to Biased FDs you get an increase in accuracy but a subsequent decrease in stability. The general rule is that for Central FDs you need to increase the number of nodes to increase the accuracy, and for Biased FDs you need to increase the number of nodes to increase the stability.
Biased FD methods are generally best for highly convective problems, such as steep temperature fronts.
The main disadvantage of Finite Difference methods is that they are not good for irregular geometries.
We have had some success using the UBFD4 finite difference method for highly advective systems.
The Orthoganal Collocation methods are better for irregular geometries. They also give better accuracy with fewer points and consequently less calculation time, but are not well-suited for steep gradients. Also as the number of points is increased theSolution quickly becomes more complex as all nodes are used in theSolution for each point.
Keywords:
References: None |
Problem Statement: How to suppress the message boxes while ACM is under the control of a VB application? | Solution: To prevent the messages to be displayed while ACM runs with automation, you need to make ACM not visible, ie
objACM.application.visible = false
before you run the simulation (or before the conditions that trigger the message are encountered).
There is no other method. You can make ACM visible afterwards if you wish.
Keywords:
References: None |
Problem Statement: How to modify the line styles in graphic definer? | Solution: If you want to add new line styles in drop down list of graphic definer, then you need to modify the 'style.sym' file which is located at C:\Program Files\AspenTech\Basic Engineering x.x\UserServices\bin\template\styles by default. The styles defined in this file are automatically loaded on the Graphic Definer
Below is the explanation on how to do it:
- In graphic definer, open' styles.sym' from C:\ProgramFiles\AspenTech\BasicEngineeringx.x\UserServices\bin\template\styles
- Draw a line|select it| and pick Format|style and press 'new' button
- Create your own style e.g. 'line style A' you can choose the base and modify its style from 'general' tab.
- Press Ok and save the 'styles.sym'.
- Reload the workspace. New added style should be available in drop down menu.
Keywords:
References: None |
Problem Statement: In Aspen Plus the results for vapor/liquid mixture can be displayed for liquid, vapour or total phase. Is it possible to display the results for the total phase in Aspen Custom Modeler (ACM). | Solution: Currently, there are no procedures available to evaluate the total phase properties and only phase=L and phase=V procedures are available.
To estimate the total phase properties, the phase fractions for the vapor and liquid phases should be reported first and subsequently, the total phase properties can be determined as the sum of vapor and liquid fractions in mole or mass basis.
Keywords: Total, Phase Properties
References: None |
Problem Statement: Import from Aspen HYSYS is not retrieving certain pieces of data (such as mass flowrate), and other imported propertise (such as surface tension) appear wrong. How can this be fixed? | Solution: Cleaning up registry and then running the regcontrols.bat file should resolve this problem.
To clean up the system registry, run the bjacregclean.exe file located in HTFS+ | XEQ folder. The default path for this executable is:
C:\Program Files\AspenTech\Aspen HTFS+ 2006.5\XEQ
After double clicking on the file icon, select OK, then Search Registry to the prompts. Once the search is complete, press Cleanup, and close the window. Next, double click on the regcontrols.bat file in the same folder to complete the fix.
Keywords: import, missing, flowrate, wrong, property, HYSYS.
References: None |
Problem Statement: In Air Cooled Exchanger (Acol+), when using the 'Program will design tube layout based on input above', the number of tubes, rows, passes and tubes per row per pass are entered, and the program will determine the tube (row/pass) positions, where the X-side flow is perpendicular to the tubes, commonly known as 'crossflow'. Within a bundle, the tubes are placed in rows, where the tubeside pass-to-pass arrangement (if multiple) can be positioned to 'flow' in the same direction as the air (X) side flow, co-current; against the X-side flow, counter-current; or perpendicular to the X-side flow, crossflow.
Some users may be confused with this setting, because derived from Shell & Tube Exchanger, for an air cooled exchanger the air side flow will always be perpendicular to tubeside flow, therefore cross-flow. Please see below the definitions of 'Co-current' and 'Counter-current' in Aspen Air Cooled Exchanger (Acol+). | Solution: The tube layout/pass arrangement can be set either entering input data to specify the bundle or using the interactive method, as described inSolution 125260.
When the 'input method' is used, on Input | Exchanger Geometry | Geometry Summary | Geometry tab there is a setting marked as 'Tube side to outside flow orientation' with three options - 'Counter-current' 'Co-current' and 'Crossflow'. The definition of 'Tube side to the outside flow orientation' is described as: the main direction of tubeside flow in terms of adjacent pass-to-pass direction against the outside (air) flow direction.
Below are two tube layout diagrams showing 'Counter-current' and 'Co-current', where the numbers inside the circles represent the tube pass:
Counter-current:
Co-current:
There are two situations where this feature will not be taken into account:
1. When the tube bundle is a single-pass one.
2. When the tube layout input method 'Use interactive graphical layout to define tube layout' is chosen rather than 'Program will design tube layout based on input above' method.
Co-current or counter-current flow will affect the thermal performance of the exchanger. In general, counter-current flow will give a higher duty.
Keywords: Tube side to Outside flow orientation, Counter-current, Co-current, crossflow, co current, counter current
References: None |
Problem Statement: Can I copy variables from Aspen Air Cooled Exchanger and Aspen Shell & Tube Exchanger to Aspen Simulation Workbook (ASW)? | Solution: Starting with EDR V7.0 a new Copy/Paste functionality has been added to the Aspen Shell & Tube Exchanger, Aspen Air Cooled Exchanger, Aspen PlateFin, Aspen Fired Heater, and Aspen Shell & Tube Mechanical programs, allowing input and result variables shown in the EDR user interface to be copy/pasted into Aspen Simulation Workbook(ASW).
Keywords: ASW, copy, paste, variable
References: None |
Problem Statement: How can I estimate the power requirement for the electrical motor in an Air Cooled exchanger? | Solution: Aspen Air Cooled exchanger (formerly Aspen Acol+) reports the Absolute Power (winter/summer) on line 59 and 60 of the Results | Results Summary | Overall Summary | Aircooled Summary page. This Absolute Power is based on the combined efficiency of the fan and drive.
Therefore Electric motor power can be estimated as Absolute Power/Motor Efficiency.
Keywords: electric motor, fan power, power, acol+, fans, aircooled
References: None |
Problem Statement: In HeatX with geometry data (rigorous calculation mode) you can specify the dimension of the tubes in different ways:
inner diameter and thickness
outer diameter and thickness
inner and outer diameters
I have specified the inner diameter to 20 mm, and the tickness to 2 mm. However I find that if I specify the inner diameter to 20 mm and the outer diameter to 22 mm, the HeatX does not give the same results. Why? | Solution: . You could rewrite it to say:
Problem Description
Aspen Plus says that 1+1 = 2, but perhaps 1 + 1 = 3.1416?
Solution
In fact 1 + 1 really does = 2
I hate to have to use the Rejected status, but here goes - I'm sure you understand....
Ben
Creation Date: 16-Mar-2001 08:42AM
Applicable Version(s):
any
Keywords:
References: None |
Problem Statement: How to find the position of the maximum or minimum element in an array? | Solution: If you need to find the location of the maximum after run the simulation run has completed, a script is probably the bestSolution. You could use a similar technique to the Fortran example below.
For run-time, oneSolution is to use a procedure. See the model below, which features an array of temperatures. The maximum value is found using the ACM MAX function. The location of the maximum is found using a procedure. The source code for the procedure is given below. For large arrays, it may help to return analytical derivatives.
Model tmax
n as integerparameter (5);
ns as integerset ([1:n]);
T(ns) as temperature_abs;
Tm as temperature_abs;
for i in ns do
T(i) = 273.15 + i*sin(i*time);
endfor
// find the maximum
Tm = max(T);
// find the location
L as realvariable;
call (L) = pMaxLocation (T);
End
Procedure pMaxLocation
library: maxlocation.dll;
call: maxlocation;
implementation: subroutine maxlocation.f;
language: fortran;
inputs: real(*);
outputs: realvariable;
End
Source code for the procedure:
SUBROUTINE MAXLOCATION(x, n, xloc,iflag)
IMPLICIT NONE
INTEGER n
DOUBLE PRECISION x(n)
DOUBLE PRECISION xloc
DOUBLE PRECISION xmax
INTEGER Iflag,i
iflag = 1
xloc = 1
xmax = x(1)
do i=2,n
if(x(i).gt.xmax)then
xloc = i
xmax = x(i)
endif
enddo
RETURN
END
You can modify the Fortran code to return the minimum value of the array.
Keywords: array index
max
min
References: None |
Problem Statement: When I run HTFS+ 2006.5, I see the Error Message, Run-time error '430': Class does not support Automation or does not support expected interface. | Solution: This error message may occur if you have multiple version of HTFS+ installed on your machine, where after running an older version and then trying to run HTFS+ 2006.5 the following error occurs.
The work around is to
1. From the Aspen HTFS+2006.5 shortcut run the Version Control Utility
2. In the Current Version tab, listed should be a number of different versions of HTFS+, with a check against Version 21. Select an older version and then click on the Set button (this will un-register version 21 and register the selected version)
3. Highlight version 21.0 and then click on the set button (to re-register version 21, HTFS+ 2006.5)
4. Exit the Version control utility
Now HTFS+ 2006.5 should run. If you subsequently run an older version of HTFS+ then you will need to repeat the above procedure each time you run HTFS+ 2006.5 again. To prevent this behaviour, then open a case in HTFS+ 2006.5.
1. From the Menu select Tools | Program Settings
2. Select the Advanced tab
3. Check the box Register HTFS+ components when program starts up and click OK.
Now you should be able to run multiple versions of HTFS+.
Keywords: None
References: None |
Problem Statement: Can we run an Aspen Custom Modeler (ACM) model with free inlet port variables in Aspen Plus or HYSYS? | Solution: When an ACM model is run in Aspen Plus or HYSYS, the inlet port variables will be fixed and should stay fixed. There is no backwards calculation of inlet stream variables; the information flow is one way. The model should be developed and run in ACM with fixed inlet port specifications.
Key Words
ACM Model, Free Variable, Inlet, Aspen Plus, HYSYS
Keywords: None
References: None |
Problem Statement: How to perform a steady state optimization in Aspen Custom Modeler (ACM). | Solution: The first step is to make sure that the steady state ACM file runs with no errors. It is a good idea to carry out a sensitivity analysis of the ACM model by varying the values for the fixed variables at the inlet of the model and observe the convergence.
In the attached file, the methanol reactor model, the inlet flow of reactants A and B are varied to optimize the conversion of the reactor. In this case, the objective function is the conversion of the reactor. Therefore, first the steady state mode is selected in the set up form:
and then the reactor conversion is dropped onto the objective function form. To do this the “all variables� table for the reactor needs to be opened and then the conversion variable can be selected and dropped on the objective function form.
Upon selecting the minimization or maximization to be achieved for the objective function, then the manipulated variables (decision variables) can be selected from the “all variables� table of the reactor and dropped onto the Decision Variable form.
If there are constraints to be satisfied by the optimization solver then they need to be specified in the constraint form.
The last step in the workflow is to change the run mode to optimization and run the file.
The updated values for the objective function and the decision variables can be found in the corresponding forms that were used to specify these variables.
Keywords: steady state optimization, objective function, decision variables
References: None |
Problem Statement: You have a vector in Aspen Custom Modeler that is indexed by a String Set, like:
1. a vector containing component-dependent quantities like molar fraction (indexed by ComponentList)
2. a vector of quantities dependent on the name of the connections for a multiport (indexed by ConnectionList)
For a particular calculation you need to send this vector to Fortran code using a procedure call from Aspen Custom Modeler.
The problem is that in ACM the order the elements of a vector are stored in memory changes with the alphabetic order of the strings in the stringset.
For example if x is declared as:
x(ComponentList) as realvariable;
and the ComponentList has been created to refer to the components A and B, then x(B) is transferred as x(2) to the Fortran code.
But if I add a new component of name AB to the list of components then, x(B) is transferred as x(3). What is the best way to avoid changing Fortran code whenever ComponentList is changing ? | Solution: This is by design. The same problem occurs when ACM is interfacing with the Aspen Plus property layer.
OneSolution is to copy the arrays of molar fractions to a temporary storage area, and reorder them as appropriate before calling the Aspen Plus property monitor. Another vector copy and reordering has to take place afterwards if the function called returns a vector.
While there are other possibleSolutions (like prefixing your component names with the letters A, B, C ... or setting up your code to assume the component list is always alphanumerically sorted) theSolution of reordering is the most general one.
In version 2004.1 and above you can also use the utility routine ACM_GetComponents to access the names of the components of the relevant stream type. It is intended to be used from procedures that specify PROPERTIES as one of the options in the procedure definition. Please see the on-line help for an example.
Keywords: Array sorting vectors procedures
References: None |
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