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This section describes the differences that you might encounter between Aspen Plus V12 and Aspen Plus V11. In most cases, previous Aspen Plus input files and backup files are completely compatible with Aspen Plus V12.
When you open a file from a previous version, Aspen Plus displays the Upward Compatibility dialog box. If you select Maintain Upward Compatibility for Features Listed Below then Aspen Plus ignores the new features in all the areas mentioned on the dialog box (which may include new pure component databanks, property methods, built-in parameters, ADA/PCS procedures, calculated molecular weights obtained from formulas, and checking of user-specified sequence, depending on the version of Aspen Plus used to create the file).
Costing results from Exchanger Design & Rating or Economic Evaluation may change from one version to the next due to updated cost data.
Data for components in the NIST database can change from one database version to another, as NIST acquires and analyzes more data for those components. In the other databanks, specific changes may occur as noted below. If you have other versions installed, you can register another version of NIST in Aspen Properties Database Manager and on the Components | Specifications | Enterprise Database sheet specify to use that version instead of NISTV121.
New features in other areas, as noted below, may still cause different results in the new version. Flowsheet convergence may follow a different path in some cases, and flowsheets which converge only with difficulty in one version are especially likely to converge differently or fail to converge. These changes may have greater impact in flowsheets with loose tolerances due to convergence paths being different. AspenTech makes every effort to avoid making changes that result in incompatibilities with previous versions. The changes discussed in this section were necessary to correct problems (such as wrong results), to implement new features, or to improve ease-of-use.
The most important areas where you might encounter differences between Aspen Plus V12 and earlier versions are:
Fortran Compiler
Aspen Plus V12 was compiled with the Intel Fortran compiler 2017 and Microsoft Visual Studio 2017 as a 64-bit program. User Fortran models compiled with different compilers or compiler versions may not work, or may run but not be able to write to the history file, report file, and control panel. Only user models compiled with 64-bit compilers will work.
Calling 64-Bit Fortran from Other Languages
A compatibility issue in moving to 64-bit Fortran was missed in the documentation for V11. While compiling your Fortran code as 64-bit with the Intel compiler generally is sufficient as long as you did not specify the bit-width of certain types of variables, when calling from other languages there are important changes. The key changes:
Integer variables should be declared as 64-bit integers (VBA LongLong)
The hidden string length arguments remain 32-bit integers but instead of placing them immediately after each CHARACTER variable in the argument list, they are now all added at the end of the argument list in the same order as the CHARACTER arguments.
For more information, see Calling Summary File Toolkit Routines in Aspen Plus Summary File Toolkit. Search the Knowledge Center for this document.
File Menu
The File menu has been reorganized. Version Comparison and Edit Compound File can now be found under the Tools sub-menu. Recent Files can be found under Open, which also features a new command there to open files from the Examples folder.
Plant Data
Two kinds of databases are used with Plant Data with names based on names you specify. Each database name is limited to 128 characters total.
The distance database contains the project name, the data conditioning run name, and about 17 other characters.
The variable list database name contains the model name without extension twice, and about 26 other characters.
Avoid using very long names for the model file, project, and data conditioning run names to avoid running into this limit.
Concentration Variables in EO RCSTR, RPlug, and Valve
In past versions, mole concentration variables in ACM-based models in EO (including the built-in RCSTR, RPlug, and Valve) were wrongly assigned the MOLE-DENSITY physical type, and mass concentration variables were wrongly assigned the DENSITY physical type. This also affects variables in custom reactions copying these types of variables in those blocks for use in calculating a custom term. Now these are correctly assigned the MOLE-CONC and MASS-CONC physical types. For many users this will not have any impact, since these types have equivalent units, and in all built-in units sets they have the same units. Additional units have been added so that both pairs of concentration and density units support the same units, so there will not be any issue importing these variables from previous versions of Aspen Plus. However, if you are using a custom unit set where these types do not have the same units, the units these variables appear in have changed in V12. If you are running the model in Aspen OnLine, the required physical type for mapping these variables has changed.
Columns
In Column Analysis, when you specify the overall section efficiency on the Design Parameters sheet, RadFrac now scales the reported section height by dividing by the efficiency. This better reflects the intent of this efficiency (adding more real trays to meet the separation effectiveness of the specified number of theoretical trays) and is consistent with the treatment of pressure drop with respect to efficiency.
In rate-based RadFrac blocks, the way the HETP is calculated for binary systems has changed. You will see different HETP values on the Efficiencies and HETP | Packing HETP sheet for such systems and the help attached to that sheet explains the calculation.
The calculation of % Downcomer backup (Aerated) for trays with Lattice downcomers was incorrect in previous versions. The absolute Downcomer backup (Aerated) was correct but the percentage result will be different in V12.
A change made in version V9 was missed in earlier compatibility notes. The pressure drop correlation used with Sulzer-Nutter float valve trays, Koch-Glitsch Ballast trays, and Koch-Glitsch Flexitrays (other than the fixed valve type S) in Column Analysis was updated. Starting in V12, you can check the Use legacy pressure drop correlation box on the Design Parameters sheet to use the correlation used in V8.8 and in legacy sizing and rating forms.
Batch Flowsheet Results
By default, stream results forms in batch flowsheets and certain profiles in BatchOp now update only when the simulation is paused or stopped. This improves performance of batch flowsheet runs. Strip charts still update continuously. There is an option on the Batch Options | Setup | Main sheet which restores the behavior of version V11 where these forms update after every time step.
As a side-effect of this performance enhancement, all batch flowsheet models saved from earlier versions will lose profile results and time plots when opened in V12. You can run the simulation again to regenerate these results.
FluidBed
The default convergence method for holdup and pressure calculations was changed in this release from Brent (the original method used in FluidBed) to RootN1 (a method used widely throughout Aspen Plus). This method solves some problems Brent cannot, and may lead to different results than in past versions for some problems. Select Brent for these options on the FluidBed | Input | Convergence sheet to restore the behavior of previous versions.
Super-saturation Results
BatchOp and RCSTR were not using the same definition of super-saturation in the results as in the input. Where C is the concentration and Csat is the saturated concentration:
On the Results | Crystallization sheet of both blocks, relative super-saturation was formerly reporting C/Csat and now correctly reports (C-Csat)/Csat (the fraction by which the concentration exceeds saturation).
On the Profiles | Crystallization sheet of BatchOp, super-saturation was formerly reporting C/Csat and now correctly reports C-Csat (the amount in concentration units by which the concentration exceeds saturation).
Super-saturation was added to the Results form, and relative super-saturation was added to the Profiles form, as defined above.
Stream Property Analysis
When analyzing stream properties for a stream that has both input and results calculated in the current session, as in the case of a tear stream you may have initialized, Aspen Plus now uses the stream results for the analysis. Previously, it always used the input if there was any input; this could have caused the analysis to overwrite the stream results, or fail with an error if the input did not include a composition.
Chemistry
When selecting the Concentration basis for Keq for reactions in Chemistry blocks, the options Mole-frac and Molal have been changed into Mole gamma and Molal gamma, respectively. This better reflects the meaning of these options and establishes consistency with the similar option for equilibrium reactions in Reaction blocks, where the Keq basis field has been renamed to Concentration basis for Keq for consistency.
Calculation Options
The default for the phase equilibrium check on the Setup | Calculation Options | Check Results sheet is now to issue a warning, the default tolerance is 0.1, and the default minimum mole fraction is now 1.0E-10. These settings help Aspen Plus better detect situations in which the flash calculation produces an invalid result. You may observe warnings related to this check generated in cases which did not generate warnings in previous versions (usually in cases where a result did not make physical sense).
When a liquid phase is missing during EO synchronization of a three-phase stream, and that phase is not dropped, the SM liquid-liquid split algorithm from the Setup | Calculation Options | Flash Convergence sheet is now used to determine a pair of components most likely to result in a liquid-liquid phase split. If the new algorithm is selected, and this results in initialization problems that lead to EO convergence problems, try selecting the original algorithm.
Polymer Reactions
In free-radical reactions, the calculation of terminal double bonds represented by TDBFLOW had twice the contribution it should have had from termination by disproportionation reactions. Other attributes such as MWW, MWN, LCB, and FLCB which are calculated in part based on TDBFLOW were also affected. These results are corrected in V12 and differ from previous versions by an amount depending on the prevalence of termination by disproportionation within your reaction system.
In V9, the molecular weight distribution plots from blocks with polymer reactions were changed so that the weight fractions for each site were normalized against the total polymer at that site. In V8.8 and earlier, these plots showed weight fractions normalized against the total polymer at all sites, resulting in a set of site curves that sum to the cumulative molecular weight distribution. The former presentation was more informative, as it shows the relative contribution of each site, and so we have reverted to the plots from V8.8. Only the plots from unit operation models were affected; the values of molecular weight distributions and other attributes in streams were not affected by either change.
Physical Properties
In past versions, the results for ideal gas heat capacity (CPIG) calculated with DIPPR equation 107 might become very wrong at very low temperatures due to a bug in the handling of a numerical overflow condition. The actual temperature at which the bug occurs depends on the values for elements 3 and 5 of CPIGDP and is only likely even at cryogenic temperatures when one of these elements is unusually large. The values are correct at higher temperatures. The problem has been fixed and values for ideal gas heat capacity (and properties using it) may change in V12 only in cases where you were getting the wrong results in the past.
Errors in the way symmetric and unsymmetric electrolyte NRTL methods (ENRTL-RK and ENRTL-SR) calculate mixture entropy and Gibbs free energy (GMX, SMX) using the apparent component approach caused these properties to not always agree with the results using the true component approach. In cases in which this was true, the results for those properties using the apparent component approach will be different in V12, but they will now agree in true and apparent approaches.
When NIST TDE performs consistency tests, it applies only the EOS and endpoint tests to high-pressure data sets (P > 500 kPa) because the other tests may not be accurate in such conditions. This change was introduced in the TDE delivered with V11 but first reported in compatibility notes with V12.
In past versions, the D2887 property sets D2887T, D2887WT, and D2887CRV were calculated using liquid volume percent, even though the actual ASTM distillation curve D2887 is weight basis and the help claimed they were on weight basis. Starting in V12 they actually are calculated on weight basis and D2887TLV, D2887LV, and D2887CVV have been added to calculate the properties on liquid volume percent.
When you regress property parameters in V12, by default an analysis is run after the regression to check the results against the experimental data. This check helps you detect cases where the regressed parameters perform poorly, which is generally because some specification for the regression differs from the configuration of your main model. The default plot for the regression plots the result of this analysis, rather than the results calculated within the regression itself as in past versions. These extra calculations cause the regression to take longer, but usually the extra time is negligible. In rare cases the analysis may lead to property errors.
In the new version of NIST-TRC in the NISTV120 database, one compound was removed. That compound was H2-N5 which was a duplicate of H2-PARA. If you were using it please switch to H2-PARA.
The parameters for H2O-CO2 and H2O-H2S for the CPA model were updated based on a new regression. Results will change but should better predict the water content of natural gas streams with high acid gas content.
The parameters UFGRP and UFGRPD, which contain the UNIFAC constituent groups of molecules for standard UNIFAC and Dortmund-Modified UNIFAC, respectively, were incorrect in PURE36 and PURE37 released with Aspen Plus V10 and V11 for certain components. In V12 these errors have been fixed in those databanks and in PURE38. For some components, the group numbers were incorrect but represented valid groups, or the quantities of a group were incorrect, and you would have gotten incorrect results in any calculations using them. In other cases invalid group numbers appeared in the databanks and you would have gotten errors attempting to use them. The affected compounds are:
Alias Name CAS Number
CH3BR METHYL-BROMIDE 74-83-9
C3H6S TRIMETHYLENE-SULFIDE 287-27-4
C4H10O-D1 METHYL-ISOPROPYL-ETHER 598-53-8
C4H10O2-N2 ISOBUTENE-GLYCOL 558-43-0
C6H10S DIALLYL-SULFIDE 592-88-1
C6H12-4 CIS-2-HEXENE 7688-21-3
C6H13N-D3 N-ETHYL-2-METHYLALLYLAMINE 18328-90-0
C6H16O3SSI 3-TRIMETHOXYSILYL-1-PROPANETHIOL 4420-74-0
C7H5N3O6 2,4,6-TRINITROTOLUENE 118-96-7
C7H10S-D1 2,3,5-TRIMETHYLTHIOPHENE 1795-05-7
C7H16O-E2 ETHYL-TERT-PENTYL-ETHER 919-94-8
C8H8S THIAINDAN 4565-32-6
C9H10S 2-METHYL-THIAINDAN 6165-55-5
C9H15N TRIALLYLAMINE 102-70-5
C9H22O3SSI 3-MERCAPTOPROPYL-TRIETHOXYSILANE 14814-09-6
C10H20-D3 1,1-DIETHYLCYCLOHEXANE 78-01-3
Databanks PURE20, PURE22, and PURE24 are no longer delivered. These are superseded by later versions of PURE which include more recent data from DIPPR and other sources.
Each of these databanks is from a version of Aspen Plus more than ten years old. They were intended only for users who require complete compatibility with results from previous versions. Because most users have now updated their simulations to newer database versions, these old versions are being dropped to reduce the size of the database delivered with each installation.
It is possible to use the Aspen Properties Enterprise Database to preserve copies of these databanks if you still need to use them. A copy of the enterprise database from an earlier version (V7.3 through V11) which still contains these databanks is required; this can be downloaded from AspenTech Support. See Maintaining Access to Retired Databanks for details.
When you open files which reference these databanks, the Upward Compatibility dialog box will appear. An option at the bottom of the dialog box lets you choose to either Upgrade retired databanks or Keep retired databanks. Choosing upgrade replaces PURE20, PURE22, and PURE24 with PURE38. The keep option requires a database containing the retired databanks.
In previous versions, the Polymer Attributes sheet for reactors using Step-Growth reactions reported incorrect values for DPW, MWW, and PDI attributes. The Step-Growth Model cannot calculate higher moments and as a result cannot calculate these attributes. In V12 the results for them will be blank.
Safety Analysis
Improved Line Sizing Results
In V12, a number of changes were made to line sizing in the Safety Analysis environment:
In V11, the reference conditions used for pressure drop calculations incorrectly discarded energy. In Aspen Plus V12, the correct reference conditions are used for pressure drop calculations.
In the Safety Analysis environment, when performing rigorous Aspen Hydraulics line sizing in V11, for the inlet pressure drop, swage calculation settings were applied to inlet pressure drop calculations and the full pressure drop (including recoverable losses) was incorrectly included in results.
In Aspen Plus V12:
For the inlet pressure drop, inlet pressure drop calculations use the Crane – Homogeneous fitting loss method and exclude acceleration pressure drop.
The performance of the outlet pressure drop was improved, and the calculated pressure drop results are more accurate.
In the Safety Analysis environment, when performing rigorous Aspen Hydraulics line sizing in V11, the tolerances for an Aspen Plus PH or PS flash were not tight enough to obtain accurate derivative-based properties over small variations in pressure for single-component systems. This reduced the accuracy of the sonic velocity calculations and line choke pressure. In Aspen Plus V12, flash tolerances were tightened for these flashes in the Safety Analysis environment (including for Hydraulics-based line sizing).
In Aspen Plus V11, the Inlet Pressure Drop [%] column on the Scenarios tab reported the inlet pressure drop as a percentage of the maximum allowable pressure, and the Outlet Pressure Drop [%] column reported the outlet pressure drop as a percentage of the maximum allowable pressure. In V12, both these values are reported as percentages of the set pressure.
In V11, an excessively low critical velocity could be reported for Hydraulics line sizing on a system with all liquid relief. This was resolved in V12.
As a result of these improvements, you will notice differences in line sizing results in Aspen Plus V12.
Updates to Storage Tank Calculations
In previous versions, for Storage Tank vent calculations under API 2000 6e or API 2000 7e, evaporation rate was doubled if Volatile Liquid selection was Yes. This was corrected in V12.
In previous versions, wetted area calculations for tank emergency relief for horizontal tanks were not consistent with the wetted area calculations for horizontal vessels. The tank calculations were changed to agree with the vessel calculations in V12.
Updates to Fire Scenario Calculations
In previous versions, there was an issue with required orifice area calculation in the flash table for Supercritical Fire scenarios, which could also lead to selecting the wrong relieving condition in certain scenarios. Note that only the required area within the flash table was incorrect; the required area on the scenario was calculated correctly. This issue was corrected in V12.
Previous versions did not correctly calculate the wetted area for vertical vessels with ellipsoidal heads at low liquid levels. This issue was corrected in V12.
Retired Features
Importing DXF files into the Icon Editor has not worked since the support for exporting DXF files was removed in version V7.3.2, but a nonfunctional Import DXF command remained. That command has now been removed.
The Aspen Process Manual button on some forms has been discontinued. To access the content it provided, visit the Knowledge Center or click the In-Context Guidance button.
Aspen OTS Framework is no longer available in V12. We recommend that you use Aspen Operator Training to accomplish the same tasks instead. Aspen Operator Training supersedes and improves upon the functionalities available in Aspen OTS Framework, as well as offering additional features. For further information about Aspen Operator Training, refer to the Aspen Operator Training Help.
In V12, aspenONE Exchange has been replaced with Aspen Knowledge. Aspen Knowledge is a web-hosted collection of resources such as help documentation, technical articles, models, literature, and on-demand training that you can view. It includes all the materials available in aspenONE Exchange, as well as additional features (such as Aspen Knowledge In-Context). For further information, see the Aspen Knowledge Overview topic.
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