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Problem Statement: The control panel does not show all the run messages, it cuts off some important sections, for example the calculation sequence in the beginning of the messages. | Solution: The control panel buffer is limited to 200000 characters and 5000 characters when simulation is running. This was done for performance reasons. It is NOT to configurable since increasing the buffer size has drastic effects on the performance when the control panel is open during run or when it is opening.
Thi... |
Problem Statement: When setting a Rupture Disc under the Safety Analysis Environment, when you use the Relieving Phase Method as Flow Resistance method and check the Sizing case results, the results are no generated, they appear as <empty>. | Solution: In order to avoid this, the following procedure must be followed:
1. Having created a Rupture Disc on any stream, create a scenario under the new rupture disc:
2. Set the pressure under PRD Data | PRD specifics | Set Pressure:
3. Under Scenario tab, click on Sizing Case:
4. Add some data under... |
Problem Statement: I've two fluids with viscosity of 1 cP (WATER) and another at 100 cP (COMP2) 0C, I wish to use a mass average mixing law:
           ln (mumx) = x1 ln(MU1) + x2 ln(MU2)
With
           x = mass fraction
           MU =Viscosity
With an excel calculation I should ... | Solution: There is the MUASPEN model to calculate mixture viscosity by mole or mass fraction. The option code determines the mole or mass fraction.
Aspen Liquid Mixture Viscosity Model (MUASPEN) is a correlative model and it is essentially a new mixing rule for calculating the mixture viscosity from the pure component ... |
Problem Statement: Murphree efficiency cannot be used with the true species approach with Gibbs free energy, but vaporization efficiency can be used. Why is this? | Solution: Murphree efficiency is not valid for a reactive system. You may get a reasonable result but it is only by chance.
The Murphree efficiency is used to account for departure from phase equilibrium stage only. It really should not be used for reactive systems (kinetic or equilibrium reactions) at all as the amo... |
Problem Statement: I looked at | Solution: 131011 and I wasn't able to find my combination of fortran compiler and visio studio. Is it possible to add it manually?
Solution
You can try adding your own configuration to the compilers.cfg file fromSolution 131011. You can open the compilers.cfg file using notepad, and you will notice that there are multi... |
Problem Statement: How to plot Consistency Test results from NIST TDE experimental data. | Solution: The NIST TDE has the capability to perform consistency test over VLE data. This test tells the user how well the calculated data fits the experimental data. The easiest way to review the results is by plotting the consistency test results together with the experimental points.
The following procedure shows ... |
Problem Statement: How do you model a Fired Heater? | Solution: An industrial furnace or direct fired heater is used to provide heat for a process. They are used in boiler applications in chemical industries or for providing heat to chemical reactions for processes like cracking. The heat energy to fuel a direct fired heat is supplied directly by fuel combustion. In Aspen... |
Problem Statement: What does it mean when you receive a warning like this on the control panel?
Flowsheet Analysis :
* WARNING DURING FLOWSHEET ANALYSIS
BECAUSE TEAR-VAR=NO IN CONV-OPTIONS, AN INFORMATION TEAR:
STREAM $WRV34 FROM PCAFL TO FST$3PCA
WILL NOT BE CONVERGED BY A CONVERGENCE BLOCK. THIS MAY CAUSE
CONVERGENCE... | Solution: This result is a warning that the variables are not being reconciled after they exit the calculator block. Since the calculator blocks modify the results of some streams, this causes the results to be wrong. You should tear these variables.
Calculator blocks were originally designed as a feed forward contro... |
Problem Statement: How to check the energy balance of a simulation using a Mixer?
Sometimes there are different units in a simulation that consume energy as compressors or pumps, and some others that produce energy, as turbines. One way to check the total energy balance of the simulation is by adding a Mixer.
Applica... | Solution: When there are different units in a simulation that can produce energy (turbines) or consume energy (pumps, compressors, etc), in order to check the global energy balance, a MIXER unit can be used.
Streams used in this case are WORK streams and all of them must be fed to the mixer. An example is shown below:
... |
Problem Statement: The definition of property sets for liquid-liquid equilibrium properties require careful definition by the user. In particular, the parameter KLL2 (Liquid-liquid K-value), and the mixture molar volumes are considered, as they are required for the calculation of the commonly reported ‘partition coeffi... | Solution: s 142057 and 142955).Solution
The variation of these properties as a function of temperature or pressure, for example, can be done by defining an Analysis. This has several advantages:
-parametric studies as a function of system variables (p and T) can be calculated and plotted
-thermodynamic method for the a... |
Problem Statement: I have noticed that when I save the Aspen Plus simulation in V8.4 in BKP format another file is leftover when the problem is closed called Runid.ads. Is this a new file done on purpose or should it be deleted when Aspen Plus exits? | Solution: The .ads file is an “Aspen Data Share” file. This is an XML data store used to transfer data between Aspen Plus and adjacent applications (Economics, Energy Analyzer, etc.). As part of the process to improve the speed and robustness of the activated applications we are moving away from using automation to ex... |
Problem Statement: How to hide and reveal a design specification and other objects through Automation Server in Aspen Plus. | Solution: A design specification sets the value of a variable that Aspen Plus would otherwise calculate. For example, you may want to specify product stream purity or the permissible amount of an impurity in a recycle stream.
When using Automation code, you might want to activate or deactivate design specification or o... |
Problem Statement: When the user specifies the Number of stages in a RadFrac model under the Configuration (Tab):
And then, under Streams (Tab) | Feed streams | Stage, if the user hovers the mouse over the feed definition’s box the message that appears is: ‘'Enter a Feed stage number between 1 and n+1', being “n” the n... | Solution: According to the convention that determines how the feed stream is introduced into a column stage. The feed stream convention related to ‘Above-stage’ states that this will be introduced between stages, above the designated stage:
Hence, when the user tries to introduce a stage higher than the latest one “n... |
Problem Statement: Why is the number of trays reported in the activated APEA different from the number of stages specified in Aspen Plus column Block specification? | Solution: In Aspen Plus, if the Murphree Efficiencies are not specified for the Aspen Plus column stages, Activated APEA will apply a default tray efficiency of 0.7 which is a design criteria whilst sizing and evaluating the column. Hence the number of tray section reported in APEA = Number of Aspen Plus Column stage... |
Problem Statement: What is the relationship between holdup and residence time? | Solution: If you specify residence time, the liquid holdup used in the rate law is calculated on a mole basis as liquid mole flow from stage times liquid residence time.
Aspen Plus calculates the liquid holdup as follows:
HOLDUPL(N) = TIMEL(N)*L(N)
where N is the stage number
HOLDUPL is the molar holdup in kmol
TIM... |
Problem Statement: The following questions on using the Pressure Relief block may arise:
1. Is it possible to run several pressure relief modules in parallel in one Aspen file, or is it recommended to only run one in a simulation.
2. There is the option to have up to two inlet and two tail pipe sections. Does this me... | Solution: Answers to the above questions are as follows:
1. Multiple pressure relief blocks can be run in parallel. They are treated like separate runs. The only issue could be with the run times. Some pressure relief cases are very lengthy, especially those with difficult flash convergence.
2. When two tail pipes are ... |
Problem Statement: In Aspen Plus I am unable to export my simulation into Aspen Energy Analyzer | Solution: Before exporting the simulation to Aspen Energy Analyzer the user will need to make sure that the simulation is not on the 'Auto-Run' mode. Inside the Run Settings, on the home ribbon, the user can confirm that the Auto-Run mode is deselected. It is recommended to have the Aspen Plus simulation saved in a fol... |
Problem Statement: How to get access to property values in the Plex using the offset utility DMS_IFCMNC and parameter name. | Solution: DMS_ALIPOFF3 function allows users to get the offset of a property in the Plex such as GAMMA and GAMUS. Using this method, 29 is the property index for ln(GAMUS) and 24 for ln(GAMMA). However, there is an easier way to get access to physical properties in the common dms_plex. The integer function DMS_IFCMNC o... |
Problem Statement: What is the reference for the Equations for Tube Rupture? | Solution: The
Keywords: None
References: Stream for the tube rupture case should be the high pressure side stream (whichever side of the heat exchanger operates at the higher pressure).
Generally speaking, for tube rupture to be applicable you want the high pressure side to operate at at least 1.5 times the design pres... |
Problem Statement: When using the Aspen Properties Enterprise Database (APED) Manager on Citrix and logged on as a Restricted User, we cannot find the menu Create a new database in the Action menu.
When using a local install, everything works fine. Why would this happen on Citrix? | Solution: When using the Aspen Properties Database Manager to create a new custom database or modify an existing custom database, the customer has to login Citrix with an account having Windows Administrative privilege. The account also must be in the “sysadmin” group of the SQL server instance that was used to restore... |
Problem Statement: How do you write Fortran expressions? | Solution: We are adding a new help topic with some simple instructions on how to use Fortran since so many new engineers have no experience with it. It is important to note that Fortran expressions are used not only in the Calculator block, but on other forms such as Design specification and Sensitivity. Also, basic Fo... |
Problem Statement: How can I check the results of the downcomer geometry of a RadFrac column? | Solution: When the user does not specify any information about the downcomer geometry (widths/weir lengths), it is possible to check the dimensions considered by Aspen Plus in the Report of the RadFrac column. To do so, the user needs to run the model, then click on the Report option in the Home ribbon:
Then, select th... |
Problem Statement: When modelling a process in Aspen Plus, is it possible to transfer the flowsheet (streams, unit operations) to a PDF file format.
I am using PDF-XChange 4.0 writer, but sometimes some unit operation symbols are not displayed in the PDF file. | Solution: There is another software which is called XPS Document Writer, that allows the user to create a file with the flowsheet drawing. This software belongs to Microsoft, so it is installed by default when using this operating system.
To “print” the flowsheet as a document, go to File | Print and select from the dr... |
Problem Statement: How to obtain results for user defined compounds VLE binary interaction properties using UNIF-DMD property method? | Solution: In order to obtain results for user defined compounds VLE properties using UNIF-DMD property method:
1) Run the attached example .aprbkp simulation file and some errors will be shown in the Control Panel:
2) Go to Components | Molecular Structure | B and C | Functional Group (tab), change the Method ... |
Problem Statement: How to export simulation from Aspen HYSYS or Aspen Plus to Aspen Process Economic Analyzer? | Solution: A converged simulation could be easily exported to Aspen Process Economic Analyzer using the Send to APEA option under the Economics ribbon tab as shown in the screenshot. Please note that you need to uncheck the Economics Active option in order to activate the Send to APEA option. Both cannot be active at th... |
Problem Statement: What is method by which the relief load is calculated for two-phase flow using the Flow Resistance (Kr) method? Is the Kr method appropriate for two-phase flow?
What is the relieving temperature is used for two-phase flow with the Flow Resistance (Kr) method? | Solution: The Flow Resistance method determines the calculated size of a pressure relief system by analyzing the total system resistance to flow.
This analysis takes into consideration the flow resistance of the following:
· the rupture disk device
· piping and other piping components
· entrance... |
Problem Statement: What should I do if I get a message about missing NRTL binary parameters or NRTL parameters for all components pairs are zero?
WARNING IN PHYSICAL PROPERTY SYSTEM
NRTL BINARY PARAMETERS FOR ALL COMPONENT PAIRS ARE ZERO, YOUR RESULTS MAY NOT BE ACCURATE. PLEASE REVIEW AND PROVIDE BINA... | Solution: When all of the NRTL binary pair parameters are zero, the liquid mixture is calculated as ideal. For non-ideal mixtures, this is generally not what is desired. It is essential to have binary pair parameters to accurately model nonideal mixtures. Aspen Plus has a number of binary databanks that can be selected... |
Problem Statement: AspenSplash.exe show up in task manager and Aspen Plus never opens.
Cause
This can occur when you install an Emergency Patch (EP) but not the Cumulative Patch (CP). | Solution: Always install the most recent Cumulative Patch (CP) for a version before installing an Emergency Patch (EP). The notes in the Emergency Patch should indicate the Cumulative Patch that needs to be installed.
Keywords: CP; AspenSplash;
References: None |
Problem Statement: I keep a detailed running log (in Microsoft Word) of my ongoing development work in Aspen Plus. However, I would like to add simulation-specific information/documentation to each run.
Can I put this information into the Setup|Description? It seems that I cannot use any formatting there. Is there ano... | Solution: The description is just simple text with no formatting. It is possible to to use an Excel Calculator to log the information in a spreadsheet.
You can also try saving as a compound (.apwz) file. This is really a zip file that is opened by Aspen Plus. Associated files such as .apmbd or .edr files should be embe... |
Problem Statement: How to add a reference to the Aspen Plus type library in VBA | Solution: Before you can perform early binding (https://msdn.microsoft.com/en-us/library/0tcf61s1.aspx) with Aspen Plus Automation Server, you need to add the type definitions contained in the type library for the compiler.
In VBA, from the “Tools” menu, click “
Keywords: ActiveX, VB, VBA, Visual Basic, Automation Serv... |
Problem Statement: If I have a machine with two different Microsoft Office versions installed, which version of Microsoft Excel would be used by the Calculator block in Aspen Plus?
Is there a way to select which version to use? | Solution: The version of Excel used by Aspen Plus via automation is limited by Microsoft.
The rule is that the last version that was installed on your computer is the version that Aspen Plus loads. The recommendation is to either have only one Microsoft Office version installed. If this cannot be done, you would need... |
Problem Statement: Is there a way to prioritize one Design Spec above others? | Solution: In order to nest, you can create a convergence block for each esign specification and nest the convergence blocks.
You need to create a Convergence for each Design Spec in the Convergence | Convergence folder. The Secant method is the default method used for single design specifications. The other methods ava... |
Problem Statement: What does a Murphree efficiency on a bottom stage with a reboiler mean?
Radfrac allows a user to enter a Murphree stage efficiency for the reboiler stage; however, from the definition of Murphree efficiencies, it does not make sense. | Solution: Murphree efficiencies are only meaningful on the last stage if there is an on-stage feed containing vapor entering that stage, as is typical of absorber columns. The vapor can come from a feed stream or an internal stream such as a pumparound. If Murphree efficiency is defined to be other than 1 on the last s... |
Problem Statement: In V7.1 the Refrigeration Utilities for exchangers did not have any crossover temperatures. In V7.3 the exchangers report errors because of crossover temperatures.
A file created in V7.1 runs and converges; however, when you run the simulation in V7.3, the following error is displayed:
** ERROR
T... | Solution: The error message is correct. The problem was that temperature crossovers were not checked or reported in V7.1 or earlier. Knowing that there is a temperature crossover is important to know in design.
Three modifications to consider:
1. If the exchanger is countercurrent there is a crossover. When it oper... |
Problem Statement: In the RadFrac | Packing Rating | Results, the max liquid superficial velocity cannot be reported in a unit which is commonly used to report this property in industry. How can this property be reported in units of GPM/sqft? | Solution: The user can add a custom unit to the simulation. SeeSolution 106558 about creating custom units in Aspen Plus.
In the Simulation environment, go to Setup | Custom Units. Select velocity as the physical quantity, and select ft/sec as the base unit. The conversion factor from ft/sec to GPM/sqft is as follows:
... |
Problem Statement: How are cloud point temperature and pressure computed in Aspen Plus? (TCLOUD, PCLOUD, TCLOUDL, PCLOUDL, TCLOUDU PCLOUDU) | Solution: TCLOUD and PCLOUD are the cloud point temperature and pressure, the temperature (at a given pressure) and pressure (at a given temperature) of the boundary between regions of one and two liquid phases, considering only the liquid phase. The TCLOUD calculation searches rigorously for the formation of a second ... |
Problem Statement: I cannot see stream IDs unless I zoom in very much. The stream/block IDs don't appear until only four blocks are on the screen even though there is clearly enough room to display these IDs even when all the blocks can be seen on the screen. It is rather inconvenient having to zoom in and out many tim... | Solution: There is a label visibility threshold setting that can be set to a level that was far different than the default level.
To reset the threshold, zoom out to the furthest level where you want labels to be visible, then right click in empty space to get the default pop-up menu and uncheck Hide Labels. This zoom ... |
Problem Statement: What method use to create new nodes in Aspen Plus through ActiveX Automation | Solution: Depending on the type of node you want to create the offspring for, you will need to use a different method:
For stream nodes (\Data\Streams) and block nodes (\Data\Blocks) you should use the add function of an IHNodeCol object.
The function Label works with offsets of nodes which their offsprings are generat... |
Problem Statement: Â During calculations, the sequence stops and I get an error message sayingÂ
*****SYSTEM ERROR
     HISTORY FILE REACHED SIZE LIMIT. EXECUTION TERMINATED
! Calculations terminated because of ASPEN PLUS internal errors | Solution: This error message appears because the history file created during the simulation is much bigger than the upper limit defined in Aspen Plus.
In Aspen Plus V8.6 a new option was added on the Setup | Calculation Options | Limits sheet to limit the size of the history file. This is a rough limit, checked about o... |
Problem Statement: What is the OOMF scripting syntax to use for the QUERYVARS function to select which variables will be updated with the restore command? | Solution: The QUERYVARS function returns list of variables using the specified query string.
These query function can be used to return lists of variables or other objects.
You may use the QUERYVARS function to enter a query. For example, to get
a list of variables whose names begin with CVAP and whose values are l... |
Problem Statement: In Aspen Plus when some parameters are not used within the models, those can be accessed by user or in-house models. For example, the values of the coefficients for the DIPPR second-virial coefficient equation (SVRDIP). | Solution: These values can be accessed form Aspen Properties Database Manager:
· From the desktop click Start | All Programs | AspenTech | Process Modelling VX.X | Aspen Properties and launch Aspen Properties Database Manager.
· Click on the database APVX.X | Select compounds.
· Click on Find Co... |
Problem Statement: Can you calculate the cricondenbar and cricondentherm in Aspen Plus? | Solution: The cricondenbar and cricondentherm are defined as follows:
Cricondenbar refers to the highest pressure at which liquid and vapor phases can exist at equilibrium in a multicomponent system.
Cricondentherm refers to the highest temperature at which liquid and vapor phases can exist at equilibrium in a multicom... |
Problem Statement: How can I create and report a .log file generated from a COFE run simulation? | Solution: The .log file from a COFE simulation file shows the information about the thermodynamic systems, as well as property package used during the calculations. The procedure shown below provides the steps to create and report a .log file generated from a COFE run simulation:
1) Open the .fsd file using the C... |
Problem Statement: How do we match assay boiling points with ASTM D86 curve data entered? | Solution: In order to verify the input values in D86 curve and the results you can add the prop-set property D86CRV to a material stream to see if the system can reasonable reproduce the input D86 distillation curve.
The bubble point (TBUB) and dew point (TDEW) temperatures of the streams are dependent on the property ... |
Problem Statement: How to use Excel in Calculator Block | Solution: Using calculator with Excel can be as easy as using fortran or even easier and flexible.
As Excel give more flexibility to do customize calculation, most user prefer to use Excel with Calculator block.
Use Excel with Calculator Block
First, User has to define all the variable need to import from simulation fl... |
Problem Statement: An orifice plate can be modeled in Aspen Plus with the pipe model. How can I check for choked flow in an orifice plate? | Solution: The resistance from the orifice is converted to some L/D, which is added to the length of the pipe to calculate pressure drop. However, if I am interested in checking for choked flow in the orifice plate, it is important to specify the location of the orifice plate.
The way to model this would be to add a pip... |
Problem Statement: In Aspen Plus software there is the possibility to click on recent cases, when opening the program. This feature may not be suitable for the users who would like to restrict access to the previously run simulation files.
This may be problematic in situations that computers are shared amongst many u... | Solution: The list of recent files is not new to Aspen Plus, it was available in previous versions from the start page or the file menu. The list of recent files is stored on a per user basis.
The list of files is stored in file called application settings which can be found in 'DRIVE:\Users\USERNAME\AppData\Local\As... |
Problem Statement: How the parameter 'a' is calculated in the flash point estimation methods FLPT-PM and FLPT-TAG? For which components is it available? | Solution: The parameter 'a' in these two methods is available for all components since its value only depends on the MW and an experimental parameter 'k' that takes only two different values, one for FLPT-PM and other for FLPT-TAG (it is not component dependent).
In this two methods, the flash point is calculated as a ... |
Problem Statement: When a user specifies Design Specifications in a column (RadFrac), one can see this in the Components Tab that for some variables there is also an option to specify Base Components. When is this option made active and when will they be used?. We would also like to know how Aspen Plus uses this select... | Solution: For Mass/Mole/StdVol purity and Mass/Mole/StdVol Ratio calculations which one can select in Column| Design Specification| <name> folder| Specification tab, Aspen Plus can use different basis for calculations.
For example Stream purity is calculated by:
Where:
x - is a component fraction, on a mole, mass, or s... |
Problem Statement: How do you use the Custom Stream Summary to remove zero flow components or add phase results? | Solution: If you want to exclude components in the report in the graphical user interface, you can use the Custom Stream Summary or a TFF file; however, you will need to explicitly exclude specific components. Currently, there is no way to do it automatically for all components with zero flow. This means that rows for ... |
Problem Statement: Ideally when you install Fortran there is an option to allow the installation wizard to update the environment variables automatically and if this option is not selected then you need to set these path addresses manually. Visual studio is also needed to be installed on your computer to link the files... | Solution: It would perhaps be easier if Fortran compiler could be re-installed and to select the option for environment variables to be updated automatically. But you can also fix this manually by checking and changing, if necessary, the following SYSTEM environment variable for your computer (from Windows start menu r... |
Problem Statement: How to specify Heat Capacity of non-conventional component to a fixed specific value for entire simulation model? | Solution: Sometimes user need to fix the heat capacity of non-conventional component throughout the simulation model. For this user need to specify manually the heat capacity fixed value in to the correlation equations available for non-conventional component in Aspen Plus properties environment.
Follow the steps below... |
Problem Statement: How do I implement a simple customized kinetics for considering a reaction rate in a CSTR? | Solution: There are various options to consider: you could use the user subroutine kinetics in a RCSTR or use Aspen Custom Modeler to create a USERACM reaction type. The first approach (user subroutine) requires you install the appropriate fortran compiler. Refer to the documentation for more information.
Nevertheless,... |
Problem Statement: I want to access and modify the FORTRAN subroutine files for an example provided in C:\Program Files (x86)\AspenTech\Aspen Plus Vx.x\GUI\App folder. How can we get the FORTRAN source code for any of these examples? | Solution: AspenTech provides majority of the FORTRAN source codes for the example files under \\GUI\App for the Users (except for source codes on urea and ammonia case studies). To obtain the FORTRAN codes, User needs to double-click the .apwz file (a compound file) provided for many of the examples. A folder with the ... |
Problem Statement: Chemistry packing column diverges in an electrolyte system, with equilibrium reactions and some components present in trace level. The column uses the Rate-Based calculation method. | Solution: ThisSolution provides a recommended configuration aiming to improve convergence in the aforementioned scenarios. The method comprises the change of three parameters; one relative to general block convergence and other two concerning specifically RateSep calculations. Note that equilibrium-based iterations are... |
Problem Statement: How to change the property method in a block using Aspen Plus Automation Server. | Solution: With ActiveX Automation Server, users can use external Windows application to interact with Aspen Plus through a programming interface using a language such as Microsoft's Visual Basic.
With the Automation interface, users can:
· Connect both the inputs and the results of Aspen Plus simulations to oth... |
Problem Statement: How to check stage wise hydraulic parameters in Radfrac column? | Solution: RadFrac profiles hydraulics sheet gives the option to view profiles of column parameters used for tray and packing hydraulic calculations.
Open above attached file
Then activate check box as “Include hydraulic parameters” under Blocks/Column/Analysis/Report
Results can be viewed under Profiles/Hydraulics
Keyw... |
Problem Statement: The Aspen Plus user interface is a COM Automation Server. The Automation technology enables an external Windows application to interact with Aspen Plus through a programming interface using a language such as Microsoft's Visual Basic or C#. This | Solution: s shows how to do the connection from Matlab.Solution
Linking Aspen Plus is not officially supported or tested; however, it should be possible. The code below illustrates how to do the linking between Aspen Plus and Matlab:
function aspenlink
AspenVersion = 'apwn.document'; % Progid of Aspen Plus document c... |
Problem Statement: Simulation with RadFrac column (Scrubber) diverges when using true component electrolyte approach with the following error message:
*** SEVERE ERRORCMBAL CALCULATIONS FAILURE: RERUN WITH CHANGES SUGGESTED IF THERE ARE ANY.
The above error is produced for different reasons, however in this case it is ... | Solution: ThisSolution provides a recommended workaround by changing the electrolyte simulation approach to apparent component under the Electrolyte Wizard (Properties Environment):
Having set this modification, go to the Simulation environment and restart/re-run the simulation. The error message will be gone and the s... |
Problem Statement: A user will often need to create Ternary diagrams using the distillation synthesis button in the Simulation Environment in Aspen Plus and they would like to know how Aspen Plus calculates distillation boundaries that are drawn within this diagram. | Solution: In order to have a background about ternary map and distillation boundaries, the user can find this under the Aspen Plus Online Help in the chapter: Locating Azeotropes and Distillation Region Boundaries. In this description the user can find general information about residue curves, azeotropes and how distil... |
Problem Statement: When using RBatch the batch reactor at a certain time, one of the reactants goes to zero, therefore no more reaction should take place. However, the total mass keeps on increasing. Why would this happen? | Solution: This can happen when the rate expression is not dependent on the concentration of the feeds, i.e. no exponents are added under Driving Force on the Kinetic sheet of a General type reaction. When the rate is not dependent on concentration, the rate is not zero even if a reactant is zero. This means that the pr... |
Problem Statement: New Feature in Aspen Plus V7.2 - Unit Operation Models | Solution: The following enhancements were made to unit operation models in Aspen Plus V7.2.
Columns
Fair72 jet flood method provides a much closer fit to Fair's original graphical correlation than the Fair method previously available in Aspen Plus. Fair72 usually predicts higher flood points (lower percent of flooding)... |
Problem Statement: In the BatchFrac model the option of specifying a reflux ratio, etc. on a STDVOL basis can be confusing. | Solution: Only use STDVOL basis when modeling petroleum/hydrocarbon components.
STDVOL is the Standard liquid volume at 60 F and 1 Atm, and is commonly used in the petroleum industry.
Note that the standard liquid volume flow (STDVOL) can be very different from the volumetric flow rate of a stream. The standard liquid
... |
Problem Statement: Is it possible to recycle materials between batches? | Solution: Yes. Materials can be recycled from a vessel between batches. The recycle input form is provided as an option in the Charge operation. On the Required tab, click on the 'Details' button next to the Material field to be loaded and then click on Recycle to specify the recycle stream and policy. One can recycle ... |
Problem Statement: If you want to be able to fit a boundary layer thickness of the flow in an RPlug block as a function of the distance from the inlet, you need the current point along the RPlug axis where the solvers are integrating so you can take this distance and calculate the boundary layer thickness in external F... | Solution: Look for the argument list for the Kinetic Subroutine in the Aspen Plus User Models documentation (e.g. AspenPlusUserModelsV7_1-Ref.pdf) which is available on the Documentation DVD or from the Documentation link on the support website.
In the section Kinetics Subroutine for USER Reaction Type, the variable XC... |
Problem Statement: Why does the calculated density for NACL (dissolved in water) from different databanks vary markedly? | Solution: In Batch Plus, when a solid is dissolved in the liquid phase, the mixture properties will be calculated using the liquid state parameters. Depending on the availability of parameters, the liquid density is calculated using different methods in this order:
Pure Liquuid:
If the DIPPR parameters (DNLDIP) are ava... |
Problem Statement: Can you create a .PDF file of the Process Flow Diagram or of the report (.rep) file? | Solution: Aspen Plus cannot be used to create a PDF file; however, many other programs such as Microsoft Office have this capability. For the flowsheet drawing, simply select all and copy [CTRL+A, CTRL+C], go to PowerPoint, paste [CTR+V], and save as PDF or just use a screen grabber. You can make the report file into a... |
Problem Statement: I have a block that does not properly initialize when I switch from the sequential modular (SM) strategy to the equation oriented (EO) strategy. How can I configure the EO model to solve in this case? | Solution: The Perturbation layer can be applied to a block to allow it to solve within EO when it is not properly initialized. By default, any unit operation model that is not supported by EO is solved in the Perturbation layer. However, you can tell Aspen Plus to solve supported unit operation models in the Perturbati... |
Problem Statement: If comparing Radfrac vs Petrofrac and using subcooling in the condenser, the stage 1 temperature will not be the same in the Profile results> TPFQ tab and Profile results> Hydraulics tab.
The profiles section is Found in the Radfrac or Petrofrac folder at the bottom. There you can find 4 main tabs: T... | Solution: Since RadFrac has the subcooling option inside the Total Condenser type, the profile results convention is different from the Petrofrac that has the two type of condenser, Total and Subcooled.
This is only a difference in convention and does not affect the overall performance of the column, for example:
For R... |
Problem Statement: How does Aspen Plus calculates the venting requirements for storage tanks? | Solution: Concerning the required capacity, we do not calculate the required capacity from the API 2000 equation. For the fire scenarios we run a dynamic simulation with the vessel and relief system specified by the user and calculate the flow through the relief device based on the conditions in the vessel and the rel... |
Problem Statement: When I run the simulation file, the results for convergence and calculator blocks are not shown. How do I display these results? | Solution: It is possible to turn off some of the items included in the report file for a simulation on the Setup | Report Options form. This will also cause the results to not appear in the User Interface (See .bkp example file attached). If some results are not showing even though the simulation has executed, check th... |
Problem Statement: When using a RBATCH reactor and you try to export an input file with a continuous feed input from a previous Aspen Plus version, for example V7.3 the following error message is shown in the control panel: | Solution: The issue when you try to export an input file with a continuous feed input from a previous A+ version is related to an invalid set of units in that previous version, located under RBATCH (model name) | Setup | Continuous Feeds | ‘Specify flow vs time profile’. On the new GUI (Graphical User Interface), there... |
Problem Statement: My HEATX heat exchanger is bypassed. The error is
Block: BOILER Model: HEATX
** ERROR WHILE GENERATING RESULTS FOR UNIT OPERATIONS BLOCK: BOILER
(MODEL: HEATX)
COLD STREAM IS HOTTER THAN HOT STREAM
BLOCK BYPASSED | Solution: The problem in this file is that the cold stream was connected to the hot stream port of the HEATX rather than the cold stream port.
To solve this problem, the connections need to be reversed by disconnecting and reconnecting them to the correct port. If you hover over the port on the block, a pop-up help box... |
Problem Statement: When I open the data filter on the Equation Oriented (EO) variables, the pull down list has ALL and all individual variables listed. What can I do if I want it to list only temperature variables? | Solution: There are a number of simple ways to filter the EO Variables list.
For example, using the EOGSG2.bkp example from the Examples\GSG_EO directory, the EO Variables from Block CONDUA initially has:
If you select a Physical Type of Temperature, you will get all of the variables with a type of temperature:
I... |
Problem Statement: How is the power requirement for a CRUSHER block calculated? | Solution: The power requirement for a CRUSHER is calculated using the following equation and based in a wet crushing operation.
Where:
The BWI is a semi-empirical parameter that depends on the properties of the material processed and it defines the work consumed in size reduction. These indices have been measured exper... |
Problem Statement: I have a Hierarchy block in my simulation. Is there a way that I can move everything inside into the main flowsheet? | Solution: You can right-click on the Hierarchy block select Move selection.
You can use the Extract hierarchy contents and delete option. Clicking on OK will prompt you to resolve ID conflicts if there any. Ater you resolve conflicts, all the objects will be transferred into the main flowsheet.
Keywords: Hi... |
Problem Statement: Mass concentration unit <<weight/volume>> is not included on the Design-Spec and Sensitivity Analysis variable define form, however this unit is extensively used in biochemical processes, e.g. bioprocessing, biofuel industries.
How can this unit be handled on Design-Specs and Sensitivity Analysis? | Solution: Mass concentration [weight/volume] can be included on a Prop-Set and then used in Design-Specs, Calculator blocks and Sensitivity Analysis.
Any property set property can be accessed using the Stream-Prop type of data available on the Define sheet. It is important to note that only one property value can be ... |
Problem Statement: What could prevent me from connecting to the remote Aspen Properties Enterprise Database (APED) server?
Cause
This may happen as Server is not configured for remote access and/or Windows Firewall is blocking access. This can happen with either SQL Server Express or Enterprise. | Solution: Please follow the following steps to configure a SQL Server to be used by remote users.
1. Enable protocols.
2. Configure Windows Firewall (different procedures for Windows Server 2008 and 2012).
3. Restart the service and verify they are set to start automatically.
Please see the attached pdf fil... |
Problem Statement: How to define a solid when it is dissolved in a solvent?
Applicable versions
All versions. | Solution: A solid can be defined in Aspen Plus as a Conventional Inert Solid (CI Solid) or Nonconventional Solids (NC Solids). In some processes there are solids in aSolution and at the end of the process they can precipitate coming back to the solid phase. In these cases, the solid must be defined as a Conventional In... |
Problem Statement: How is IONSMÂ (Ionic strength in molality scale) property set calculated in Aspen Plus? | Solution: Ionic strength in molality scale is defined as follows:
Where
m -the ionic concentration in units of molality
mo - 1 mol kg-1
zi - charge number of component i
Keywords: Ionic strength, IONSM
References: Atkins, P. W. Physical Chemistry, 3rd ed.; Oxford University Press: New York, 1986. |
Problem Statement: What do green xs around a flowsheet mean? | Solution: When the flowsheet is locked, a green cross-hatched border appears on the flowsheet.
XXXXXXXXXXXXXXXXXXXX
You can use Lock Flowsheet from the Section section of the Modify tab of the ribbon to lock the flowsheet to prevent unintended changes. This prevents you from adding, deleting, or renaming blocks and s... |
Problem Statement: Is it possible to make a Ternary Phase plot for a Cellulose/ Solvent/ Water (polymer-liquid-liquid) system?
According to the literature cellulose gets dissolved in the solvent/water system only at certain compositions. They are trying to incorporate this dis | Solution: in Aspen Plus.
Solution
The ternary plot does not apply to systems containing polymer or oligomer components. However, you can still setup a Flash3 block to perform liquid-liquid equilibrium (LLE) for a system containing Cellulose and Water.Attached is an example file, LLE-Cellulose-V84.bkp, for such a cal... |
Problem Statement: How do you get the Flowsheet window back in Aspen Plus V7.3.2 after closing it? | Solution: Go to the View tab and select Flowsheet from the Show section of the ribbon. This is also the place where you can re-open the Start Page.
Keywords: None
References: None |
Problem Statement: Where is the help menu in Aspen Plus V7.3.2? What is the best way to get to Help? | Solution: There are a few ways to get Help in Aspen Plus.
1. To launch Help, select the small Show Help button from the far right of the ribbon.
Contents: Browse through the documentation, including User Guides and
Keywords: None
References: Manuals
Index: Search for help on a specific topic using the index entries
Sea... |
Problem Statement: When creating a new property method NRTL-GLR based on WILS-GLR where the liquid gamma is changed to GMRENON, the heat duty with WILS-GLR and NRTL-GLR are different.
NRTL-GLR takes account heat of mixing (though heat of mixing is unchecked on Properties | Specifications form), while WILS-GLR does not... | Solution: When you modify the model from GMWILSON to GMRENON, the GMRENON model will be used in all calculations that require an activity coefficient gamma model. This includes the heat of mixing effect. That's why you get a different heat duty.
To not include the heat of mixing effect, you must change routes for liqu... |
Problem Statement: Increasing number of significant figures shows only zeros. Is it possible to increase precision of the results? | Solution: Internally, all calculations in Aspen Plus are done in double precision using SI units. The results are reported in user units with eight significant figures. The significant figures can not surpass 8 since this is how many are saved for the report data. However, customers can change the unit of the wanted pr... |
Problem Statement: I am using the NRTL-HOC property method in my simulation. When I run my simulation it converges fine but I get the following error message when trying to view the stream results form for any block:
Can you tell me why this is happening?
Application Version(s)
V7.3, V7.3.2, V8.0, V8.2, V8.4, V8.6 | Solution: This error is displayed because Aspen Plus was not able to determine the mixture viscosity MUMX listed in the property sets HXDESIGN and TXPORT and display it in the stream results when this property set was selected to be included in the stream report under Setup | Report Options | Stream Tab.
The reason f... |
Problem Statement: In a HeatX model using rigorous design method with EDR, the outlet temperatures in the EDR environment don't match the temperatures reported in Aspen Plus.Why is this? | Solution: The differences between the results in EDR and A+ are caused by the hot or/and cold stream properties having inappropriate temperature points. If you look in the EDR browser after accepting the design, you will see that the Hot/Cold Stream Properties has most points located in the two-phase region:
There aren... |
Problem Statement: Control objects' labels wrap around, making them unreadable (See Figure 1).
Figure 1. Aspen Plus V7.3. GUI. | Solution: This problem occurs when your computer?s screen is set to use large fonts and can be fixed by
changing the Windows display settings.
Steps to fix this issue:
For Windows 7.
1.Right-click on your desktop, and select Screen ReSolution
2.Select ?Make text and other items larger or smaller?
3.Select the r... |
Problem Statement: The shortcut to find which use to be Ctrl+F9 in V7.3 and earlier is missing in the new user interface. | Solution: The find dialog is now tied to CTRL+F shortcut keys (to be consistent with HYSYS and other products).
Once you are on find dialog, click the move to check box then click the find button to brings you right to the selected block or stream.
Keywords: None
References: None |
Problem Statement: How do I use the NIST/TDE database such as TDE5n.mdb with Microsoft Access? | Solution: The NIST TDE database can only be accessed through the NIST Thermo Data Engine button on the tool bar or from the Tools menu. All experimental data available can be access in this manner and the data can be saved to the Aspen Plus .bkp file and used in data regression if needed. The access database cannot b... |
Problem Statement: When using a conversion reaction inside a RadFrac block, how is the conversion considered in the calculations? | Solution: If conversion reactions are used inside a RadFrac block, the reaction rate is calculated for each reactive stage using the specified conversion, the key component, and the total flow rate of the key component (including vapor and liquid streams entering the stage and the feed streams to that stage).
In the ... |
Problem Statement: When I run the simulation in Customize Aspen Plus then how to review an error summary report? | Solution: When you run your simulation model in Customize Aspen Plus by using input file then it is difficult to trace errors. If you want to check the errors while running the file in customize option you have to go through following procedure.
1) If you go to Start | All programs | Aspen Teach | Process Modelling ... |
Problem Statement: After Install of V7.3.2 of Aspen Plus The Start Page Shows the following error:
HTTP Error 407 Proxy authentication required. | Solution: Some background info:
The Web server (running the Web site) thinks that the HTTP data stream sent from the client (e.g. your Web browser) was correct, but access to the URL resource requires the prior use of a proxy server that needs some authentication which has not been provided. This typically means you mu... |
Problem Statement: In RCSTR, when you have multiple phases, you can specify RES-TIME (overall residence time) or phase residence time. | Solution: When you specify residence time, the reactor assumes no-slip conditions between the phases. This implies the vapor fraction in the reactor is the same as in the mixed outlet stream. Since the molar volume of vapor is >> molar volume of liquid, this makes the liquid residence time very small. This assumption i... |
Problem Statement: The default node values are in mass basis, how can I retrieve the enthalpy and entropy in molar basis? | Solution: There are different ways to retrieve the enthalpy and entropy in the molar basis:
1. Use the ValueForUnit function of that node to read in the desired basis,
enthMolar = mySim.Tree.FindNode(Data\Streams\S1\Output\HMX\MIXED).ValueForUnit(39, 2)
2. Change the HAP_UNITROW attribute for that node so that ... |
Problem Statement: How to generate ASTM curves from a particular stream. | Solution: 1. Right click on a particular stream
2. Select Analysis
3. Select Dist-curve
4. Click in Go
The ASTM curves will be generated as a table
Keywords: ASTM, curve, Distillation curve
References: None |
Problem Statement: This Knowledge Base article provides steps to resolve the issue of Aspen InfoPlus.21 not starting accompanied by the following error:
h21_arcck_local failed with ret = -2120
Also, when trying to update any task in Aspen InfoPlus.21 Manager, such as trying to add NOHIS to TSK_DBCLOCK, user may receive... | Solution: Make sure that Aspen Infoplus.21 Task Service is running under a user account that has WRITE access to the Windows Registry.
If in doubt, change the account and restart the service.
Keywords: None
References: None |
Problem Statement: I'm creating a new simulation for H2O with HCl using the Elec Wizard. When I select the default property model ENRTL-RK, I am not getting the same set of pair interaction parameters as with ELECNRTL. Why? | Solution: ELECNRTL model has been available in Aspen Plus for many versions. ENRTL-RK is a new version of the electrolyte NRTL activity coefficient model which addresses some issues found with ELECNRTL - essentially to ensure ENRTL-RK becomes exactly consistent with NRTL-RK when there are no electrolytes. SeeSolution 1... |
Problem Statement: When a flowsheet is created in Aspen Plus, the most commonly required physical property parameters are automatically retrieved by the simulation engine from the property data banks.
Quite often user may need to access other physical property parameters such AIT, RON, MON, FLML, FLMU
Related | Solution: s : 3008Â and 113840Solution
Provided that the values for the required parameters are available in the databank, then the first step is to type in the name of the parameters in customize | user parameters (in properties environment) eg FLML (see screen shot)
Next by clicking the retrieve parameters tab in th... |
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