question stringlengths 19 6.88k | answer stringlengths 38 33.3k |
|---|---|
Problem Statement: How to read our Adobe Acrobat documentation? | Solution: User needs an Adobe Acrobat reader. This can be downloaded from a number of sources, including www.adobe.com.
Keywords: Version 10, Adobe Acrobat, reader, .pdf, documents
References: None |
Problem Statement: How Are Reaction Rate or Kinetics Affected by the Reaction Stoichiometry Written? | Solution: In Aspen Plus, the amount of reactants converted and products generated depends on how one enters the stochiometric coefficients. The kinetics expression in Aspen Plus is expressed as the rate of change in the Extent of Reaction. For a reaction:
aA + bB -> cC
(1)
If we use the symbol, E, to stand for the exte... |
Problem Statement: Why do residue curves lines sometimes stop abruptly in the middle of a curve? | Solution: Every point on each of the residue curves represents a liquid composition. The curve end point is the initial composition of the liquid. Additional points are obtained by plotting liquid compositions as differential amounts of vapor are removed from the liquid.
If a line on a residue map stops abruptly, it is... |
Problem Statement: How do I read or write to the Control Panel and to Aspen Plus Files? | Solution: for Calculator Blocks:
In Fortran WRITE statements in a Fortran Calculator block, you can use the following predefined variables for the unit number:
Unit
Destination
NTERM
Control Panel (if running from the user interface)
Terminal (if running interactively outside of the user interface), or
Log file (if run... |
Problem Statement: In the Aspen Plus HEATX unit, how should a user enter the number of tubes in a U-Tube bundle? | Solution: Specify the number of holes in the tubesheet as the tube count and then specify two tube passes. In a U-tube bundle a long tube is bent into ''U'' shape. While it is physically one tube, for modelling purposes it is two separate tube segments. One segment has flow to the right, and the other segment has flow ... |
Problem Statement: How does a user obtain access to the Phillips Petroleum proprietary Assay Library? | Solution: There is a utility (provided to Phillips Petroleum by AspenTech) that takes data from the Phillips Crude Library and generates Aspen Plus bkp files. These partial backup files can be stored into the asy directory of Aspen Plus GUI installation. The files can then be opened by or imported into Aspen Plus.
For ... |
Problem Statement: It is possible to to create a .dll for a Calculator block that
does not change to either save time or to give the model to someone without a compiler? | Solution: This is not currently possible in Aspen Plus.
Here are a couple of things that could be done to minimize the problem:
If the problem is that there is a lot of FORTRAN code in the calculator, the user may write a FORTRAN routine and call it from the CALCULATOR. Compile the FORTRAN and link a dll.
Keywords:
Re... |
Problem Statement: Why does version 11.1 give negative displacement warnings on positive displacement compressors (COMPR block), and earlier versions do not? | Solution: The calculated positive displacement compressor results in version 11.1 and version 10.2 are identical. The only difference is the new warning message for situations where a negative disiplacement has occured.
The typical cause of negative displacement is very large compression ratios (Pin/Pout). Large compre... |
Problem Statement: For various reasons, Customer wants to run Aspen Plus 10.2 under Windows XP. During a silent install of several AES products (Aspen Plus, Aspen Dynamics, Aspen Custom Modeler, Aspen Split, Aspen OLI) an error message window appeared. A description of the error message is included below. What is aspCo... | Solution: Though AES 10.2 is not officially supported, it is often possible to install it on Windows XP. AspenTech does not guarantee that there will not be other problems since this configuration has not been tested. AES 11.1 SP1 is fully supported on Windows XP.
There is no consequences of the the missing entry point... |
Problem Statement: Which point in relief valve results gives the largest orifice size? | Solution: Aspen Plus''s pressure relief block is used to simulate a vessel undergoing pressure relief or for simple valve rating. Use pressure relief to either determine the steady-state flow rating of pressure relief systems or dynamically model vessels undergoing pressure relief due to a fire or heat input specified ... |
Problem Statement: When installing Aspen Plus 10.2 on machine that has had Aspen Plus 10.1 previously installed, the following error message occurs when trying to run a simulation or when opening the file from the GUI:
Unable to load simulation engine. Probable cause: insufficient memory or disk space. and yet there is... | Solution: This problem seems to relate to the long file names in the Path. To resolve the problem go to the registry as follows:
Click on Start>Run then type regedit then click on OK, this will open the Registry Editor.
Go to the following Key:
\HKEY_LOCAL_MACHINE\SOFTWARE\ASPENTECH\ASPEN PLUS\10.2\APLUS , Then edit th... |
Problem Statement: For RadFrac and MultiFrac, it is now possible to have a load stream for each stage or a cumulative load stream for a specified number of stages. The advantage of using a load stream is that it ensures feasible heat transfer and can be used in a MHEATX block. A cumulative load stream in RadFrac or Mul... | Solution: To specify a cumulative load stream in RadFrac, place a heat stream on the RadFrac block and redefine it as a load stream using the Data/Setup/Stream Class/Load Streams sheet. Then on the RadFrac/Heaters Coolers form, define the side heating (or cooling) for consecutive stages using the Side Duties sheet, and... |
Problem Statement: After setting up a Petrofrac model, it is possible to enter Murphree or Vapor tray efficiencies, but in some cases, the thermal efficiency forms are disabled. Why? | Solution: In some cases, the thermal efficiency entries would conflict with other entries. Specifically, thermal efficiencies are not allowed when: a) there is a pseudo stream with a phase of TL (total liquid) or TV (total vapor) b) when there is two liquid phase checking enabled below tray 1.
When the above two types ... |
Problem Statement: Can I simulate tray columns without downcomers? | Solution: No. The algorithm was programmed with the assumption that a downcomer was always present. There is no workaround.
Keywords: radfrac
tower
References: None |
Problem Statement: When used in Aspen Plus, how does an ACM exported model set the output stream properties? | Solution: If the block energy balance option is checked (as it is by default), a PH (specified pressure, specified enthalpy) flash is done. Otherwise, a TP (specified temperature, specified pressure) is done. The flash is always a vapor-liquid flash, using the same property settings as the Component list assigned to th... |
Problem Statement: I am getting incorrect results for the solubility of light gases in the liquid phase using Henry's Law with an activity coefficient model
or
I am getting the message:
SEVERE ERROR IN PHYSICAL PROPERTY SYSTEM
HENRY'S CONSTANT MODEL HENRY1 HAS MISSING PARAMETERS:
HENRY/1ST ELEMENT (DATA SET 1) MISSING ... | Solution: Both of these problems may occur because Henry's Law is not correctly specified for components. If a light gas is not specified as a Henry Component, usually the amount of that gas in the liquid phase is overpredicted.
To use Henry's law for a given component, Henry's constants must be present between the com... |
Problem Statement: How is the required cooling duty calculated for the Plug Flow Reactor (RPlug) with a specified coolant? | Solution: Heating or cooling requirements for the RPLUG reactor is calculated with a log mean temperature difference (LMTD) calculation from node to node along the length of the reactor.
Keywords: RPLUG, coolant, LMTD, node, duty
References: None |
Problem Statement: The user receives the following message after clicking the Next button:
Water must be specified as a component when Use free-water calculations option is selected (Setup Specifications Global sheet) or Water-basis = Dry is specified for a Prop-Set property (Properties Prop-Sets Qualifiers sheet). | Solution: Free Water or Water basis = dry is specified somewhere in the flowsheet. If one of these options is desired somewhere, simply add Water to the Component list. If these options are not desired, they should be removed so that inadvertent incorrect calculations are not done.
Below are three places to check:
Chec... |
Problem Statement: What is Pad gas component in the Pressure Relief calculation block
and when should it be specified as a component in the Pressure Relief block? | Solution: A pad or padding gas is an inert (N2 or Air) component that is typically added to a storage or process vessel or tank to maintain its pressure at a constant value. It is mostly used in situations where the bubble point pressure of a liquid may be below atmospheric pressure or if it is desired to store a liqui... |
Problem Statement: Since version 10.1, the Aspen Plus physical property system contains new temperature-dependent property correlations from IK-CAPE. These correlations are alternatives to existing models such as DIPPR. While the available DIPPR equations are documented (Physical Property Methods and Models Guide, page... | Solution: aims to fill this information gap.
Solution
The following pure component properties can be calculated by IK-CAPE models:
Property Parameter Equation
Ideal gas heat capacity CPIGPO IK-CAPE polynomial (eq. 1/401)
Liquid heat capacity CPLPO IK-CAPE polynomial ... |
Problem Statement: Is it possible to test for missing property parameters values in a user subroutine? | Solution: Aspen Plus uses the value RGLOB_RMISS to flag missing parameter values (i.e. values not entered by the user). The variable RGLOB_RMISS is defined in the common block DMS_RGLOB. Missing parameters are set to equal either -RGLOB_RMISS or RGLOB_RMISS. Therefore you need to write your code to test for the absolut... |
Problem Statement: When changing the petroleum characterization methods on the Petro Characterization / Property Methods forms, no change occurs in the calculated pseudo component properties. | Solution: The Petro Characterization / Property Method object manager allows the user to create new property methods for the calculation of pseudocomponent properties similar to the way one can create and modify simulation property methods in the Data/Properties/Property Methods folder. Changes on the Petro Characteriz... |
Problem Statement: What type of Joules are used in Aspen Plus?
Please verify whether the Joules in Aspen Plus are International Joules or Thermochemical Joules. | Solution: Aspen Plus Joules are absolute (according to Perry's 6th Edition) or international joules. The Aspen Plus conversion factors are:
1 Joule * 1055.0559 = 1 BTU
1 Joule * 4.1868 = 1 calorie
The Ideal Gas constant (R) is 8314.33 J/kmol-K in the SI units used in Aspen Plus.
All internal Aspen Plus calculations a... |
Problem Statement: In addition to Pure, Binary, and Ternary Property Analyses, how do I use the interactive Analysis features to generate tables and plots for properties of flowsheet streams? | Solution: You do not have to complete the flowsheet definition or input specifications first. For example, to check your
Property Method, you can analyze a feed stream as soon as you define it.
To analyze streams that are not specified as feed streams to the flowsheet, the stream must have results that were
calculated ... |
Problem Statement: What does it mean to deactivate a block? | Solution: Activate/Deactivate was introduced in Aspen Plus 10.2 so
that one could enable and disable different blocks and their connecting
streams in order to test different scenarios.
It is best to deactivate blocks and let the streams and other objects (design-spec, constraint, fortran, transfer, sensitivity, ...) be... |
Problem Statement: How can you find a component in Aspen Plus if you know only a common name that is not in the databank?
Often, when only a common alias name is known for a component, it is difficult to find that component using the component search utility in Aspen Plus. Most component names in the Aspen Plus databan... | Solution: There is a very helpful website, http://www.chemfinder.com , with a long list of alias names for most components. The user types an alias name and the search engine returns a list of all other known aliases and proper names for that component and most importantly, the Chemical Abstract Service (CAS) number.
T... |
Problem Statement: Which is better the DIPPR or NIST database for properties?
Is there any information available regarding a comparison of the data/results for the components in common between the two? | Solution: There are about 2000 compounds in common between NIST and DIPPR though the NIST database is much larger (>18,000 components). It is not feasible to make detailed comparison between the two databases - nor is it meaningful to do so. The parameters from these databases for the same compound will likely be diffe... |
Problem Statement: Does the Aspen Plus mol dimensional unit imply g-mole or kg-mole?
On the Reactions | Reactions (Powerlaw) form, there is a list box of dimensional units adjacent to the activation entry text box. Does the mol dimensional unit imply g-mole or kg-Mole? Some of our dimensional units say Kmol such as J/k... | Solution: The convention is that mol means g-mole. Any other mole has a prefix to indicate what type it is.
While it may seem like a simple change to convert all mol units to g-mole units, this would cause compatibility problems for models built in earlier versions of Aspen Plus.
Keywords: SI
References: None |
Problem Statement: When using the SR-Polar property method, the following error message occurs during the simulation:
*** SEVERE ERROR IN PHYSICAL PROPERTY SYSTEM
EQUATION OF STATE MODEL ESHOC HAS MISSING PARAMETERS: MUP (DATA SET 1) MISSING FOR COMPONENT 1,4 DABE
What does this message mean and how can it be avoided? ... | Solution: ESHOC refers to the Hayden-O'Connell (HOC) Equation of State and MUP is the dipole moment parameter used in it. The Hayden-O'Connell model uses the dipole moment (MUP). Other models such as NRTL-HOC would give a similar error message if MUP is not present for a component.
SR-Polar uses HOC to estimate paramet... |
Problem Statement: VBA Example to take control (Open/Run/Close/Reinit) of an Aspen Plus simulation via ActiveX automation. | Solution: The attached Excel file contains a Visual Basic for Application (VBA) code that will:
Open any Aspen Plus simulation.
Run the simulation.
Reinitialize the simulation.
Close the simulation.
This example could be used as a starting point for building a VBA interface to retrieve specific Aspen Plus results.
To r... |
Problem Statement: My simulation in sequential modular mode (SM) runs fine; however, when I switch to equation oriented (EO), it fails immediately. | Solution: If theSolution fails in EO at the first step, the solver may be trying to solve too aggressively. To solve less aggressively, turn on Creep mode on the Convergence \ EO Conv Options \ DMO Basic \ Basic sheet. It is suggested that you turn it on for 10 iterations with a step size of 0.1 or 0.2. Another indicat... |
Problem Statement: In Aspen Plus 11.1, it is now possible to give pseudocomponents some properties such as sulfur content using the Components, Pseudocomponents, Petro Properties sheet. Can you explain what Aspen Plus does with this data? | Solution: The pseudocomponent properties do not have any effect on the Property Set property. The implementation of pseudo component properties has not been completed for Aspen Plus 11.1.
Attached is an example using user Property Sets to achieve the same calculations.
The methodology is to create a user parameter, i.e... |
Problem Statement: When trying to regress parameters, the case converges very quickly and the parameters remain at their initial values and have a standard deviation greater than 1e+10..
->Data Regression begins ...
BEGIN CASE CP TIME = 0.46
STARTING POINT TIME: 0.46
BL-ITER: 1 SSQ: 0.783739E+03 REL CHANGE: 0.0... | Solution: This generally occurs when the parameters have no effect on the data. For example, this can occur when the parameter CPLDIP is regressed to fit liquid heat capacity data and a liquid reference state or DHL09 is not used. For this case, either CPIG needs to be regressed or a liquid reference state needs to be ... |
Problem Statement: What is Free-water and how should it be used? | Solution: Free-water refers to the water layer in a system where two liquid phases are present and the water phase contains essentially no organic. In Aspen Plus, this is an option for three-phase separation. When Free-water = Yes, the second liquid phase (L2 phase) is treated as PURE water (no organic). In other words... |
Problem Statement: How to the Access Dechema Data in Aspen Plus through the Internet and what are the commercial terms? | Solution: You can use the DETHERM Internet Client to access thermophysical property data in the DETHERM online database, maintained by DECHEMA e.V., Frankfurt am Main, Germany.
You can search for properties of given mixtures or pure components. The retrieved data are automatically placed on the Aspen Plus Properties Da... |
Problem Statement: Is it possible for an RStoic to determine the products of a combustion? | Solution: You can check the Generate combustion reactions on the Setup | Combustion sheet of an RStoic to have it automatically generate combustion reactions.
Full combustion is assumed when this option is specified: all carbon is converted to carbon dioxide and all hydrogen to water. The nitrogen combustion product ma... |
Problem Statement: How to read our Adobe Acrobat documentation? | Solution: User needs an Adobe Acrobat reader. This can be downloaded from a number of sources, including www.adobe.com.
Keywords: Version 10, Adobe Acrobat, reader, .pdf, documents
References: None |
Problem Statement: How Are Reaction Rate or Kinetics Affected by the Reaction Stoichiometry Written? | Solution: In Aspen Plus, the amount of reactants converted and products generated depends on how one enters the stochiometric coefficients. The kinetics expression in Aspen Plus is expressed as the rate of change in the Extent of Reaction. For a reaction:
aA + bB -> cC
(1)
If we use the symbol, E, to stand for the exte... |
Problem Statement: Why do residue curves lines sometimes stop abruptly in the middle of a curve? | Solution: Every point on each of the residue curves represents a liquid composition. The curve end point is the initial composition of the liquid. Additional points are obtained by plotting liquid compositions as differential amounts of vapor are removed from the liquid.
If a line on a residue map stops abruptly, it is... |
Problem Statement: How do I read or write to the Control Panel and to Aspen Plus Files? | Solution: for Calculator Blocks:
In Fortran WRITE statements in a Fortran Calculator block, you can use the following predefined variables for the unit number:
Unit
Destination
NTERM
Control Panel (if running from the user interface)
Terminal (if running interactively outside of the user interface), or
Log file (if run... |
Problem Statement: Recommendations on the use of TABPOLY? | Solution: The use of TABPOLY in table or correlation form can sometimes lead to unexpected results for properties such as enthalpies, entropies, and heat capacities. TABPOLY has the
following characteristics:
The data used in TABPOLY is not regressed, instead a 3-point interpolation is executed every time that a proper... |
Problem Statement: Where are the model switching parameters (thermo and transport switches) documented? | Solution: The Aspen Plus manuals for Releases 10.0 and earlier do not include documentation about the model switching parameters. Now they are documented in the Physical Properties Methods and Models reference manual.
Aspen Plus uses the model switching parameters (THRSWT and TRNSWT) to specify which equation format to... |
Problem Statement: What are the API 1997 Liquid Viscosity and Twu Liquid Viscosity methods? | Solution: API 1997 Liquid Viscosity and Twu Liquid Viscosity methods are new for 2004.
API 1997 Liquid Viscosity
The liquid mixture viscosity is calculated using a combination of the API and Andrade/DIPPR equations. This model is recommended over the earlier API viscosity model. This model is applicable to petroleum f... |
Problem Statement: When accessing the DUTY of a unit operation block in a Calculator or Design Specification, the value is always zero. | Solution: The variable DUTY is the user specified duty set in block.
The calculated heat duty variable is QCALC. QCALC is the difference of enthalpies of inlet and outlet material streams. QCALC is set to zero if duty is specified.
The net heat duty NET-DUTY is the sum of the inlet heat streams minus the actual (calcul... |
Problem Statement: When using License Manager licensing, user cannot receives licensing error in Point | Solution: Activator not attached, missing License Key file.
Solution
This problem could be caused by the License Management Selector program being configured for Activator licensing rather than using License Manager.
Open a License Manager Status window on the Client PC and enter the command asplmadm -s. This will list... |
Problem Statement: How do you test binary vapor-liquid equilibrium data for thermodynamic consistency? | Solution: It is important to test binary vapor-liquid equilibrium (VLE) data for thermodynamic consistency since the use of inconsistent data in data regression results in poor parameter values and may cause convergence problems. When you request consistency test for a data group in a regression, you can specify whethe... |
Problem Statement: The simulation terminates with the following error message:
****EXECUTION ERROR
UNABLE TO LOAD DYNAMIC LIBRARY PPPOLY
! Calculations terminated because of ASPEN PLUS internal errors | Solution: The cause of the problem is that at least one input specification requires the presence of Polymers Plus. This could be a property method such as POLYNRTL, or a component being declared as polymer, or segment. Note that the sheer presence of any polymer-related input specification requires Polymers Plus (incl... |
Problem Statement: I am having problems converging a three phase, highly nonideal column. What are some recommendations to address problems like this? | Solution: Here are some general practical ideas that one can try when addressing convergence problems in RadFrac. The items mentioned below usually are sufficient to solve most problems when combined with patience, good analysis skills and process knowledge.
Physical properties
Pick the top five to ten most important ... |
Problem Statement: Does the condenser heat stream include the duty for subcooling? | Solution: No, Aspen Plus reports the Condenser heat stream as the duty required for condensing the vapor. This is separate from the Subcooling duty which is the duty required to subcool the product coming off the condenser (i.e., distillate). Subcooling specifications are set on the Condenser sheet of the RadFrac Setup... |
Problem Statement: Is it possible to model reactors, such as hydrotreaters, that use assays and pseudocomponents? | Solution: See the attached Aspen Plus 10.1 example file! This file can be opened in Aspen Plus 10.1 and higher.
The simplest and most direct way to model reactors such as FCCU's, hydrotreaters, and hydrocrackers is with an RYield reactor. The RYield reactor simply performs a mass balance and uses the user-specified yie... |
Problem Statement: How many baffles are needed to model an H-shell heat exchanger? There is a severe error that bypasses the block saying that the number of baffles needs to be greater than 2, even though 8 baffles have been specified? | Solution: The H-shell in the Aspen Plus HEATX block is modeled as 8 E-shells. Each E-shell needs 2 baffles so the H-shell needs 16. F-shells need 2 baffles and G-shells need 8.
Keywords: heatx
References: None |
Problem Statement: When trying to use the interface to heat exchange design programs for an existing flowsheet simulation, is it possible to add the HXDESIGN property set when it is missing? | Solution: The HXDESIGN property set is included in many of the application template (.apt) files provided with the software. The General with English Units and General with Metric Units both include this property set.
Steps
Open a new simulation with either the General with English Units or General with Metric Units te... |
Problem Statement: What equations are used in the GMMNRTL model? | Solution: The GMMNRTL is a modified NRTL model. It was modified by one of our large customers who asked us to integrate it with Aspen Plus so their engineers could use it. Unfortunately, it was never documented.
The equation for the tij and the alpha function for NRTL (GMRENON) are shown in our help and Physical Proper... |
Problem Statement: The user has selected in THRSWT/2 the value of 0 and entered DNLDIP (DIPPR density parameters) for a component.
In Aspen Plus 10.1, Aspen Plus still uses the DIPPR correlation; however, in Aspen Plus 10.2, it uses the Rackett correlation.
In Aspen Plus 10.2 if you set THRSWT/2 to 0, and do a Retrieve... | Solution: A thermoswitch (THRSWT) is a parameter that controls which form of an equation is used to calculate a thermodynamic property when there are multiple equations available. Thermoswitches are entered in the Properties/Parameters/Pure Components folder as T-Dependent objects. For more information on For more info... |
Problem Statement: As the concentrations of components in the batch reactor RBatch are inherently dynamic, what value is used in the power law model calculations and how often are they updated? | Solution: The component concentrations used in the reaaction kinetic calculations are the actual values for a given iteration. The concentrations are updated for each iteration.
Keywords: batch reactor
References: None |
Problem Statement: With Aspen Plus 11.1, it is possible to export using an XML format. What is the use of this feature?
Do you provide a starting example? | Solution: The XML file format is used in Aspen Plus 11.1 to provide an alternative way of saving the results. Having the results in this format allows one to perform searches and filtering in a much more efficient way than using VBA or the Summary File Toolkit.
For the Summary File Toolkit approach, see:
http://support... |
Problem Statement: Is it possible to model multiple immiscible phases of the same | Solution: using the FactSage Interface? Native calculations in FactSage support up to three immiscible phases of the sameSolution.
Solution
To deal with immiscibleSolution phases, it is necessary to modify the components andSolutions in the databanks.
Add theSolution phases to the FACTSOLN.TXT file in the APRSystem 11.... |
Problem Statement: In my user databank some components have incorrect names. Is it possibile to rename these components with DFMS? | Solution: Besides using the COPY paragraph to copy information from one databank to another, you can also use it to copy records within a databank. If you combine a COPY [NEW-NAMES] paragraph with a DELETE paragraph (e.g., to delete any data for a given component from a databank), you can actually rename an existing co... |
Problem Statement: How many segments should be chosen in RateFrac or RateSep for simulating packed column? | Solution: For a trayed tower, it is usually clear that each tray can be represented by a segment in RateFrac or RateSep.
However, for a packed tower, there is usually a little more involved in defining the number of segments. It is generally true that as the number of segments increases, the packing height per segment ... |
Problem Statement: How do I model an orifice in Aspen Plus? | Solution: There are a few options for modeling orifices though there is no explicit model in Aspen Plus:
Use a valve with a small valve opening.
Use a pipe model (large pipe connected to short pipe) with a short pipe length e.g. 1 inch.
Use Fortran to change the pressure drop. You will need one Fortran block for each... |
Problem Statement: Is there an easy way to model particle size increase? Most solids unit operations seem to be directed towards either separation, or reduction in particle size. | Solution: Attached is a report that presents a user model for the PSD increase in a granulator and demonstrates its use in a standalone granulator simulation and a simulation of a granulator circuit. Both simulations demonstrate how the Excel Calculator block in Aspen Plus enables useful visualization of the simulation... |
Problem Statement: What should I do if a tear stream will not converge with any convergence method
Wegstein, Broyden, or Newton? | Solution: If a tear stream will not converge, try the following steps:
Provide a reasonable estimate for the tear stream on the Stream.Main form.
Confirm that all components have a method of leaving the process. If not, the problem may not be feasible from an engineering point of view (there might not be a steady stat... |
Problem Statement: When using the option Estimate only the selected parameters for property estimation of a compound you are required to enter its molecular structure even when the compound is available in the Aspen Plus databanks.
How can you avoid the tedious step of entering in the Molecular Structure form informati... | Solution: Aspen Plus release 11.0 and higher has a very convenient feature that displays the molecular structure of components in the database. The structures can be viewed on the Properties\Molecular Structure\Structure sheet.
Many components have their structure in the database that is delivered with Aspen Plus. In a... |
Problem Statement: Is there a way to retrieve Sensitivity tabular results from Aspen Plus into Excel? | Solution: Navigate down the Variable Explorer (Under the Tools Pull down menu) to Data > Model Analysis Tools > Sensitivity and then to your sensitivity block. For example, to retreive the 3rd define variable from the tabulate form for the first case study:
Sample Path-To-Node Name for retrieving the Reboiler Duty (the... |
Problem Statement: Out of Disk space Error during DAIS core component Installation.
After installing many of the Microsoft core components, the installation halts with a message that there is insufficient space available on the target drive to complete the installation, and that you should free up more space and then t... | Solution: Look for a file called dais.ini in the windows directory and rename it to dais.bak and re-do the install. This will reset the original location of Dais so that it should not be pointing to a non-existing drive or at least it should point the installation to a drive with available space.
Keywords: Core compone... |
Problem Statement: Many components in the system databanks have values for elements 9, 10, and 11 of CPIG, the ideal gas heat capacity parameter. How are these values determined? | Solution: Elements 1 through 6 of CPIG contribute to the ideal gas heat capacity values at temperatures above CPIG/7. This is usually the temperature range used.
For temperatures below CPIG/7, elements 9, 10 and 11 are used.
CPIG/9 is a limiting value for CPIG at 0 K, which is determined as follows:
CPIG/9 = 5/2 R for... |
Problem Statement: The results in Aspen Hetran generated with the interface to Aspen Plus do not agree with the stream resuts shown in Aspen Plus. Outlet temperatures and vapor fractions are different. | Solution: The Aspen Plus interface to Aspen Hetran passes into the Hetran file a constant pressure heat release curve. Hetran designs the exchanger based upon this constant pressure VLE. Hetran then passes back into Aspen Plus the pressure conditions at the outlet of the exchanger based upon the calculated pressure dro... |
Problem Statement: Where are the changes to databanks documented when a new ASPEN PLUS release is distributed? | Solution: A file called PURECOMP.DIF documents the changes made to the PURECOMP databank since ASPEN PLUS, Release 8.5-6. You can find this file in the ModelManager executable directory (such as, C:/MM91/XEQ).
For ASPEN PLUS, Release 9.3-1, there is a file AQUEOUS.DIF that documents the changes made to the AQUEOUS data... |
Problem Statement: DECHEMA''s A_ij and A_ji parameters are converted into b_ij and b_ji respectively upon using the Dechema button on the Binary Parameters T-Dependent sheet. Is that correct? What is the conversion formula behind the Dechema button in Aspen Plus / Aspen Properties? | Solution: You can enter DECHEMA binary parameters for the Wilson, NRTL, and UNIQUAC activity coefficient property methods, and their variants in Aspen Plus and Aspen Properties, respectively. The most comprehensive source of those parameters is the DECHEMA Chemistry Data Series [e.g., Gmehling, J., U. Onken, W. Arlt, V... |
Problem Statement: Is it possible to use Aspen Plus or HYSYS to combine assays with conventional components (like any hydrocarbon), and report the combined stream distillation curve? | Solution: Both Aspen Plus 11.1SP1 and HYSYS 3.01 are capable of computing the distillation curves in the presence of conventional components. Note that in Aspen Plus there is a limitation that the distillation curve cannot be computed if less than 4 components are present.
The following is based on the TBP (True Boilin... |
Problem Statement: The RadFrac block allows specification of subcooling even when condenser is toggled to None. | Solution: When a user specifies degrees of subcooling or a subcooled reflux temperature, the RadFrac block cools the liquid from stage 1 to the specified temperature. This allows the simulation of columns in which there is a separate cooler between stage 1 and stage 2. The duty for this cooler shows up as subcooled dut... |
Problem Statement: Can I get some more details about Reid vapor pressure is calculated and can be used in a simulations? The specific questions are as follows:
1. How is the Reid vapor pressure calculated in Aspen Plus?
2. Does it match the API method documented in the API databooks?
3. What is the di... | Solution: The answers to the questions are given below:
1. The Reid vapor pressure is vapor pressure of liquid at 100 F, as measured according to ASTM D-323 procedures. Reid vapor pressure is often used to determine the appropriate type of storage tank (cone roof or floating roof) for petroleum stocks with undefi... |
Problem Statement: How can I merge two flowsheets? | Solution: Two flowsheets can be merged quite easily in Aspen Plus.
This feature is very useful for building large flowsheets
since each new piece can be tested separately and then
merged into the main flowsheet after you have it operating
to your satisfaction.
The flowsheet that is being merged into the current flowshe... |
Problem Statement: Do you have an automated way to help select a Property Method? | Solution: See the attached spreadsheet provided by one of our customers Rémy Gressly of Syngenta.
Keywords:
References: None |
Problem Statement: In a HEATER block, the temperature of the inlet and outlet streams does not match the heat curve temperature results. How can this happen given that the delta H across the heat exchanger is consistent? | Solution: In a heat curve, if Heat Duty is specified as the Independent Variable, then the heat duty will be varied at intermediate points between the inlet and outlet conditions of the block, including phase transition points (bubble and dew points). For each one of these intermediate points, temperature, pressure, va... |
Problem Statement: How can you tell if you have CH1 installed? | Solution: Selecting About Aspen Plus from the Help menu indicates Aspen Plus Version 11.1.4 for Aspen Plus 11.1 CH1.
The Version in the history file indicates VERSION: 11.1 Build 194 Patchlevel 1
The only difference in history and report files of SP1 and CH1 is the build number, i.e. 193 vs. 194. Aspen Version 11.1 was... |
Problem Statement: The Aspen Plus files Kent-Eisenberg-1.bkp and ElecNRTL-1.bkp perform the same simulation of a distillation column that strips H2S from a loaded | Solution: of aqueous DEA. Kent-Eisenberg-1 uses the Kent-Eisenberg property method, called AMINES in Aspen Properties, while ElecNRTL-1 uses the ElecNRTL property method, called ELECNRTL in Aspen Properties, with parameters from the INSERT KEDEA. Both simulations have the same feed and use column specs to attain a temp... |
Problem Statement: I have noticed that in Aspen Plus 11.1 in the EO Configuration folder there is a EO Sensitivity folder. What is it used for ? Any difference with the old Sensitivity Analysis in the Model Analysis Tools folder? And how does it compare with Case Studies?
Who can benefit from that? | Solution: In Sequential Modular (SM) mode a sensitivity analysis is carried on by repeatedly executing the blocks involved, at all possible combinations of different values of all the varied variables. A case study takes only selected combinations of values (cases) of the varied variables.
In Equation Oriented (EO) mod... |
Problem Statement: Why does the pressure relief fire scenario require specification of a fire duration as a time constraint? | Solution: Most companies have equipment to extinguish the fires so they more or less know the fire duration. Furthermore, this specification enables the user to model the effects of any external heat input, such as fire, on the rate of any chemical reactions that may be occurring in the vessel. In such a case, the fire... |
Problem Statement: User cannot run Aspen Plus independently, it can only be run through Aspen Custom Modeler / Aspen Dynamics.
The following Error message is given:
*****TERMINAL ERROR
USE OF ASPEN SIMULATION CAPABILITIES NOT PERMITTED AT THIS INSTALLATION
CALL ASPEN TECHNOLOGY, INC. AT 888-996-7001 FOR ASSISTANCE. | Solution: License key is enabled for use of Aspen Plus with other products but not stand alone.
For Aspen Plus 10.x
Check Product License Key Certificate for line stating:
Properties Plus Only: Yes
For AES 11.1
Check Vendor line in Flexlm License Key file. Look for SIMOK Parameter. If SIMOK=0; This means you can not u... |
Problem Statement: When simulating a Tungsten Hexafluoride (WF6) process, the normal boiling point is about 62 F which is reasonable. However, the vapor pressure (PL) range predicted by Aspen Plus between 0 and 150 F ranges from 2.05 E 16 to 1.5 E 16 psia. Not only are these numbers way off, but the trend produced is w... | Solution: There are some gaseous components such as WF6 in the databanks that only have limited data available for them.
The only data available are Gibbs Free Energy (G), Enthalpy (H), Entropy (S), and Heat Capacity (CP) for ideal gas. In Aspen Plus, we want to make sure that this component stays as vapor, so we make ... |
Problem Statement: How do I make a plot update automatically when a new run is made? | Solution: When any plot is the active window, from the Edit menu choose Live plot. The plot will then be redrawn when new results are available.
For plots that are created with the Plot Wizard, you can turn this on at creation by going all the way through the Wizard to the last form and checking the Live plot option bo... |
Problem Statement: How can the Aspen Plus system administrator suppress the echoing of the physical property paramaters used in a simulation despite the PROPERY-REPORT PARAMS being invoked by the user? | Solution: PROPERY-REPORT PARAMS sentence is used at user level to report all physical property parameters used in a simulation. At times, the Aspen Plus administrators would like to disable this feature to prevent the end-users from accessing proprietary property parameters.
There is no SDF table to make this change sy... |
Problem Statement: Is it possible to model a simple Chlor-Alkali cell using the RStoic block? | Solution: Here is a simple example showing how to use RStoic to represent a Cl/Alkli cell.
Each RStoic in this example represents a half cell. RStoic CL2-HALF represents the Anodic reaction and H2-HALF represents the Cathodic reaction.
ANODIC REACTION:
2CL- - 2e -> CL2
CATHODIC REACTION:
2H2O + 2e -> H2 + 2OH-
OVERALL:... |
Problem Statement: How do you enter binary temperature-dependent parameters for activity coefficient models in a User or Inhouse databank using the legacy DFMS method? What is the syntax for the DFMS input language for WILSON, NRTL, UNIQ and HENRY parameters? | Solution: The correct DFMS syntax for binary Temperature-dependent parameters is:
NEW-PROP NRTL 8
PROP-DATA
PROP-LIST NRTL 1
BPVAL C1 C2 -3.050599 1052.0 0.30 0.0 0.0 0.0 0.0 1000.000 -5.418060 2837.0 0.30 0.0 0.0 0.0 0.0 1000.000
or more generally:
NEW-PROP NRTL 8
PROP-DATA
PROP-LIST NRTL 1
BPVAL C1 C2 a12 b12 c12 d12... |
Problem Statement: Opening the Data Browser causes the error Unable to load form control. None of the forms are able to be displayed. | Solution: For Aspen Plus versions 10.0 and 10.1:
Run regfix.bat and then run ApwnSetup.exe. They are found in the folder \program files\AspenTech\Aspen Plus 10.1-0\gui\xeq. Accept all the defaults. Then try Aspen again. If it doesn''t work, go to step 2.
Install the DAO from the Aspen Plus CD. This is under i386/Syste... |
Problem Statement: How does a user add the API Upper and Lower Heating values to the stream results? | Solution: These properties are available as the Property-Set parameters:
QVALGRS (Gross Heating Value) - API High Heating Value
QVALNET (Net Heating Value) - API Low Heating Value
To add these parameters to the stream report, use the Data Browser to visit the Prop-Set sub-folder under Properties. Add a new property set... |
Problem Statement: How is the Heat of Reaction calculated in Aspen Plus? How can I see the value? | Solution: Enthalpy calculation is based on the Heat of Formation of the reaction components at reference state (DHFORM). Because Aspen Plus can calculate the enthalpy of a compound at the given conditions, the Heat of Reaction is implicitly included in the enthalpy calculations. The Heat of Reaction is the difference i... |
Problem Statement: What is the Campbell-Thodos model for liquid density and how is it used? | Solution: The Campbell-Thodos model is essentially the same as the Rackett equation for liquid mixture molar volumes except that it contains an additional term which permits varying the RKTZRA pararameter as a linear function of (1-Tr).
ZRA,mixture = sumi ( xi RKTZRA ( 1 + di (1 - Tr) )
The model uses T-dependent param... |
Problem Statement: How to the Access Dechema Data in Aspen Plus through the Internet and what are the commercial terms? | Solution: You can use the DETHERM Internet Client to access thermophysical property data in the DETHERM online database, maintained by DECHEMA e.V., Frankfurt am Main, Germany.
You can search for properties of given mixtures or pure components. The retrieved data are automatically placed on the Aspen Plus Properties Da... |
Problem Statement: How to accurately fit binary density data over a wide range of composition if consistent mixture effects are present? | Solution: In general Chemical Engineering practice the density of a mixture is not a critically important property. It becomes relevant for specific applications like:
Storage system design
Reactors (effect of density on residence time)
Most hydrocarbon systems can be modeled accurately using the default model for dens... |
Problem Statement: What parameters are needed to create a non-volatile component? | Solution: For an activity coefficient Property Method, the values of the Extended Antoine vapor pressure parameter (PLXANT) of -20 and 0 for the first and second elements respectively will make a component effectively non-volatile. This assumes that other parameters are available or will be entered for a component.
How... |
Problem Statement: What are the units of aromatic, olefin, sulfer or other petroleum assay content on the input form and also in the report file when a property set is used to report this property? Is it percent or fraction? | Solution: The units of the petroleum assay properties is mass percent or mass fraction depending on what is selected for the UNITS of measurement, e.g. When ENG is selected it is in percent, when SI is selected it is in fraction. To see this, you need to look at the Setup\Units sets\ENG\Concentration\Content which is u... |
Problem Statement: Is RATES Vector in User Kinetic Routine Packed or Unpacked? | Solution: The RATES is a vector and is one of the arguments being passed between the RPLUG model in Aspen Plug and the user kinetic subroutine. In the subroutine, RATES is used to calculate the reaction rates of each component that participate in the kinetic reaction.
A packed vector in Aspen Plus means that the vector... |
Problem Statement: What is a .apmbd file? What is it's function? | Solution: The .apmbd file is paired with the .bkp file. It contains the binary embedded component of the problem file when the simulation is saved as an ASCII bkp file. The .apmbd file only exists when something has been embedded into the process flowsheet (PFS) from another windows application or when a Calculator blo... |
Problem Statement: When defining a property set, I saw two kinematic viscosity properties: KVISC and KINVISC. Are they the same? | Solution: No, KVISC and KINVISC are not the same. Though they both report the kinematic viscosity of a mixture, one is calculated from user entered curve data and the other from internal property correlation.
KVISC is calculated directly from interpolation/extrapolation of kinematic viscosity curve as entered in the AS... |
Problem Statement: How can I access flow or composition information for electrolyte systems on a True or Apparent basis when the simulation is in the other basis? | Solution: There are a number of built in property sets (Prop-sets) for accessing just such information. The prop-set properties are:
FTRUE
FAPP
mole flow on a true basis
mole flow on an apparent basis
XTRUE
XAPP
mole fraction on a true basis
mole fraction on an apparent basis
MTRUE
MAPP
molality on a true basis
molalit... |
Problem Statement: In an DFMS input file PROP-LIST sentence such as
Prop-list MW 1 0 / TC 1 0 /
What are the 1 and 0 in these statements? Are they srcodes as documented
on page 1-12 of Release 9 | Solution: The documented syntax is:
PROP-LIST pnam1 srcode1 [ucode1]/...
where pnam is parameter name
srcode is the source code (our current documentation states use any
integer number for srcode)
ucode is the units code.
Presently, only SI units are allowed
(ucode=0). Default is 0
So, ucode does not need to be enter... |
Problem Statement: How do you automatically select a different Default working folder for each user on a server installation so that the users do not need to enter a Default Working Directory on the Connect to Engine screen. | Solution: If working directory is not entered or the entered value does not exist, the system searches the following registry entry for a working directory:
HKEY_CURRENT_USER\Software\AspenTech\Aspen Plus\11.1\aplus\DefaultWorkingDir.
For a server installation, AspenTech recommends setting the above registry as follows... |
Problem Statement: Why am I getting mass balance and strange phase problems when using the ChemApp FactSage interface? | Solution: One common cause of this problem is that one of the components for
a phase in FactSage is not defined for that phase in Aspen Plus.
For example, this problem could cause a solid gas phase.
If in one block, there was a minute amount of a solid component trying to form; however, if the component is only specifi... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.