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Problem Statement: Why is the tube layout different in EDR Thermal and EDR Mechanical? | Solution: The EDR thermal program has a tube layout generated by an HTFS routine, whilst the EDR mechanical program has a tube layout generated by a B-JAC routine. These layouts will typically be different in terms of tube location and baffle cut location.
In typical-size units (larger), these differences are not significant between the two programs. However, for smaller units, such differences can be exacerbated and cause more notorious variations in results for pressure drop.
For such cases, it is important that the final (as-built) tube layout to be the one in EDR thermal program for a more accurate pressure drop calculation.
Keywords: Tube layout, baffle, thermal, mechanical
References: None |
Problem Statement: How can I modify the Scenario Data notes from the PRD Design Booklet – Switchboard inside the Documentation Builder? | Solution: In the Documentation Builder, inside the PRD Design Booklet – Switchboard,
when you access the Scenario Data for a PRD,
you can see an entire section with notes for each scenario type. However, these notes are not editable:
To modify the information contained in these notes you need to do it directly from the Scenario Setup | Scenario Description Notes section:
Keywords: Design Booklet, Scenario data, documentation builder, scenario notes
References: None |
Problem Statement: What are the units of measurement that I have to use in the isotherm parameters in Aspen Adsorption? | Solution: The isotherm parameters are defined in the configuration block of the bed models. The Aspen Adsorption isotherm models are expressed as functions of either partial pressures or concentrations.
When you use Aspen Adsorption isotherm models for pure components or for multi-component mixtures, you must supply isotherm parameters consistent with the functional form. These isotherm parameters need to be entered in the base units of measurement which are listed in the following table:
Variable Units
Loading (w) kmol/kg
Gas phase concentration (c) kmol/m3
Pressure (P) bar
Temperature (T) K
Keywords: Units of measurement, Aspen Adsorption, Isotherm
References: None |
Problem Statement: How to report outputs from a model, to a tag in Aspen Online, if the variable does not exist in, or is not calculated by, the model unit ops. | Solution: When attempting to report certain model parameters or values in Aspen Online, the work flow is to create a Tag in Aspen Online, import a model variable, then link the Tag to the model variable. This will ensure that when the model executes, the value of that variable will be output to the linked tag. There may be variables that can potentially be calculated from a combination of model variables and therefore will not exist unless configured deliberately.
One way to create such variables could be the use of Calculator blocks inside the process model, in Aspen HYSYS a similar logical operator called a Spreadsheet can be used. Once the results are calculated in the Calculator block, model variables are created for the calculated parameters and these variables can be imported in to the Aspen Online project and linked to tags.
Another option is to create formula tags in the Aspen Online tag grid. The input to these formula tags could be target/output tags linked to model variables.
Finally, using Tags configured to store global parameter values is yet another way to get model results out to Aspen Online.
ThisSolution describes how to set up global parameters and define them within Aspen Online tags.
Global Parameters:
These are variables that are defined in script and able to store quantities, once the script is invoked. This example will create a global parameter to store mass flow of Ethylene in the overhead product of the Ethane/Ethylene splitter. This will be calculated by creating an expression of the product of Total Distillate Mass Flow and Mole Fraction of Ethylene in distillate variables.
Define a string for the global parameter representing Mass Flow of Ethylene, this string is decided by the user: C2H4MF
Next ensure that the this Global Parameter is correctly set to the EO variables for Total distillate mass flow, BLOCKID.BLK.STREAMNAME_MASS and ethylene mole fraction variable BLOCKID.BLK.STREAMNAME_C2H4.
Note that the component ID for C2H4 should be the same as in the Component List.
The script is called Global Parameter and will look like this for the C2S block, DL product distillate stream name and C2H4 component ID for Ethylene:
Take note of the parameter name as the Aspen Online Tag parameter configuration is case sensitive and therefore very unforgiving.
Save this script in the project directory. In most cases, these global parameters can be created in a script that is already invoked by the Aspen Online project, such as the Postsolve script. A better approach is to create a separate ebs file to hold the global parameters and save this in the script directory, typically the ebs subfolder. Next, invoke the script from within the postsolve script. If a postsolve is not invoked, then invoke from within any other existing script. The important point to note is that this new script should be invoked in a manner that is consistent with how the project is being executed.
Invoking the Global Parameter script from the postsolve script:
Define Tag in Aspen Online
Define a tag, this tag can be either a local tag whose value will be trended within Aspen Online, or a DCS tag that is stored in the process data historian server database. The value of this tag will be updated by a parameter, so navigate to the Parameter tab and provide the name of the global parameter.
This tag is set to update the value from the parameter after case 1 has been executed. A default value can be set but is not required.
After case 1 executes, the value of the tag will be updated by the global parameter.
Note: Be careful to use the precise parameter name as set in the script, when defining in an Aspen Online tag. If there any issues with these parameters, Aspen Online engine may fail to execute with a get/put data message.
Keywords: Global parameters, posolve, script, set paramaters, tag parameter, output tags, performance variables
References: None |
Problem Statement: How can I enter tube pass layout for symmetrical and non-symmetrical bundles in Aspen Air Cooled Exchanger? | Solution: Aspen Air Cooled allows symmetrical and non-symmetrical bundles to be entered, depending upon the data items that have been specified in the Input | Exchanger Geometry | Geometry Summary | Geometry. Symmetrical bundles will have the same number of rows per pass, whereas non-symmetrical bundles may not. Aspen Air Cooled has two options to specify these layouts:
Program will design tube layout based on input above
If this option is chosen, view the tube layout summary in Input | Exchanger Geometry | Geometry Summary | Tube Layout, as in the figure below:
Use interactive graphical layout to define tube layout
If this option is chosen, open the Tube Layout tab and click on the radio button corresponding to the desired tube pass. Next, right mouse click on the layout diagram to select the tube rows corresponding to that pass, as shown in the figures below:
Keywords: Pass layout, Symmetrical, Symmetric, Non-symmetrical, Non-symmetric, Bundle, Passes
References: None |
Problem Statement: When I try to browse for a Datasheet which I just created, I am unable to locate it. What steps do I need to take to make a Datasheet accessible? | Solution: The general workflow for creating and deploying Datasheets is as follows:
1. Create new Datasheet or edit an existing one using Datasheet Definer application.
2. Save the *.xlsm file to the Datasheets folder in the Workspace library.
3. Assign Title and Class Views under Datasheet Properties. Keep in mind that each datasheet must be assigned a unique Title that is used to refer to the sheet by an end user in the Datasheet Editor.
4. Generate the template and place *.ztf and *.ztx files to the Templates folder in the Workspace library.
5. Reload the Workspace.
Keywords: Datasheet properties, definition, class views, naming
References: None |
Problem Statement: When adding a new Miscellaneous Tag in AspenWatch Maker, the message ‘HY000: ”IODEV#” invalid value for select record “Io-Groups” possible values are “IODEV#” or “IOGROUP# ” ODBC--call failed.’ can appear if the IODEV# is not correctly defined or a different IODEV# is selected. This | Solution: proposes a way to avoid this message by manually change the record on IP21
Solution
1.- On the IP21 administrator find the Def called IoGroupsDef, then expand this Definition and you should find a selector called Io-Groups. Expand this selector and please click on #_OF_SELECTIONS, this will allow you to see the screen where we should find the logical devices.
2.- Add IODEV1 in the list, Select ON and Give permission as Read only
3.- On AspenWatch Maker go to Tag Maintenance on the tools tab and Add a Miscellaneous Tag. On the Add Miscellaneous Tag window tick on Apply same Tagname for IO address and Click Add Tag.
5.- Finally, click yes.
Keywords: Aspen Watch, IP21 Administrator
References: None |
Problem Statement: Is there a way to report additional variables for all streams in Equation Oriented mode? | Solution: Equation Oriented mode does not calculate the same variables that Sequential Modular mode does. If you want to calculate and report additional variables, (e.g. pH, viscosity, surface tension, conductivity, etc.), you need to ask EO mode to do it by adding an Analyzer block. An Analyzer block can calculate properties for a specific stream at the desire conditions (default conditions are the stream conditions).
The philosophy of the Analyzer block is to mimic the measurement systems in a real plant (and not everything is measured in real plants). So if you want to calculate a property for all streams, the best approach would be to add an Analyzer block to every stream.
In order to accomplish this, you have to do the following:
1. Create a Property Set with the variable you want to calculate.
2. Add an Analyzer block to the flowsheet. You can either connect the stream to it or reference it in the Analyzer Block Specifications form.
3. Select the Property Set in the Analyzer Block Property Sets form.
4. Synchronize the EO method strategy to create and initialize the EO variables.
5. The outlet stream from the Analyzer block is a direct copy of the inlet stream including any additional properties requested from the referenced Property Set(s).
Note that you can only have one property per Prop Set.
Now, keep in mind that the properties specified in the Setup|Report Options|Streams|Prop Set button will be calculated once the EO simulation is converged, in the same way as EO mode, so if the properties are required just for reporting purposes there's no need to even use the Analyzer block. The Analyzer block is required when you need to expose a property calculated by a Prop Set as an additional EO equation (e.g. to use it in a Spec Group). Calculating properties as EO variables when it's not really needed will increase the size of the simulation, and may cause EO convergence problems.
Keywords: Equation Oriented, EO variable, Analyzer
References: None |
Problem Statement: What are the differences between the different types of louvers in Aspen Air Cooled Exchanger? | Solution: Louvers are used to provide process side temperature control and prevent damage to the bundle due to climatic conditions. Louvers affect the outside bundle pressure drop and the price estimate. They can be defined on Input | Exchanger Geometry | Unit Geometry | Accessories
The different types of louvers in the Aspen Air Cooled Exchanger program are referring to Aspen HTFS Research network Design Report (DR54) page 55 where HTFS has studied the performance of four different types of louver blades, as shown below:
Please note that AspenTech cannot post the entire research network paper (HTFS DR54: The Control of Air-Cooled Heat Exchangers) in this article, as users will need to access to the Aspen HTFS Research Network via aspenONE Exchange: How to access the Aspen HTFS Research Network in aspenONE Engineering V8.8
For more information on the louvers, please refer to the next article: What is the effect of louvers on the outside pressure drop?
Keywords: louver, types, blade, DR54, HTFS
References: None |
Problem Statement: There are two “Automatic Pressure Assignment” options (Equalize All Versus Set Outlet to Lowest Inlet) in Mixer unit operation (figure 1). What are the suitable application scenarios of these two options?
Figure 1. Two “Automatic Pressure Assignment” options in Mixer unit operation. | Solution: These two options’ definitions can be found through HYSYS Help (“Mixer from Help.pdf” help content is also uploaded in Attachments):
1) Set Outlet to Lowest Inlet (default setting), in which case all but one attached stream pressure must be known. HYSYS assigns the lowest inlet pressure to the outlet stream pressure.
2) If user specify Equalize All, HYSYS gives all attached streams the same pressure once one of the attached stream (inlet or outlet stream) pressures are known.
In steady state modeling, both options are OK. Set Outlet to Lowest Inlet option can avoid pressure inconsistency. Otherwise, if user select Equalize All option and two or more of the attached streams have different pressures, a pressure inconsistency message appears. Please note that the Set Outlet to Lowest Inlet option will disable the backward calculation of pressure across the Mixer.
In a dynamic simulation case, we strongly recommended that user should choose the Equalize All option in order to realistically model flow behavior. With this specification, flow to and from the Mixer is determined by the pressure flow network. The “one PF specification per flowsheet boundary stream” rule applies to the Mixer operation if the Equalize All option is chosen.
Keywords: Mixer, Automatic Pressure Assignment, Set Outlet to Lowest Inlet, Equalize All, Backward calculation
References: None |
Problem Statement: When I try to copy & paste a column with internals, only the streams and specs are include. The internals information is lost. | Solution: In Aspen HYSYS, you can right click a column and copy and paste the column to another location in the flowsheet (or another flowsheet in a new simulation).
However, the new column will not include the column internals information from the old column. You will need to manually add them back if needed.
Keywords: Copy & paste
Column internals
References: None |
Problem Statement: For Fire scenarios in Safety Analysis, the additional diameter that has to be specified is internal or external? | Solution: When running Fire scenarios in Safety Analysis, parameters for the vessel(s) must be specified, one of them being the diameter. However, it is not specified if this should be inside or outside diameter.
For an API Wetted fire calculation, the diameter should be the outside diameter. For a Semi-dynamic or Supercritical fire calculation, the same diameter is used for both the exposed area calculation (outside diameter) and fluid volume (inside diameter). Outside diameter would be more conservative for heat input.
Keywords: Fire scenario, diameter, PSV, safety analysis
References: None |
Problem Statement: Are the Notes made on the different PSV forms in the Safety Analysis environment transferred to the Documentation Builder or the Built-in reports? | Solution: When sizing or rating PSVs in the Safety Analysis environment, it is possible for users to make notes on the ‘Scenario Description Notes’, ‘PRD Notes’ and ‘Rating Notes’ fields. The images below show the fields available for notes.
Notes will not be transferred to any of the Documentation Builder reports. Only the ‘Scenario Description Notes’ and ‘PRD Notes’ will be transferred to the ‘Relief Load Calculation’ and ‘Calculation Sheet’ built-in reports, respectively.
Keywords: Notes, Safety Analysis, PSV, Transfer, Documentation Builder, Built-in Reports.
References: None |
Problem Statement: Is there a way to add combination of unit operations for thermal stage and catalytic stage in SULSIM? | Solution: HYSYS offers a Thermal & Catalytic Section combinations, allowing you to add a group of unit operations organized in pre-configured topologies to the flowsheet. These unit operations are already connected by streams in defined connections.
User can add these combinations from the Add Combinations group of the Sulfur Recovery Unit ribbon or from the Model Palette │ Combinations tab.
The Thermal Section combination consists of the following:
Reaction Furnace (Single Chamber) with the Empirical furnace model selected
Single Pass Waste Heat Exchanger
Sulfur Condenser
The Catalytic Section combination consists of the following:
Heater
Catalytic Converter
Sulfur Condenser
Keywords: SULSIM, Thermal & Catalytic Stages, Add Combinations
References: None |
Problem Statement: How do I create a table in Aspen Simulation Workbook (ASW)? | Solution: 1. In MS Excel, click on Organizer under Aspen Simulation Workbook ribbon.
2. In the Aspen Simulation Workbook Organizer, paste the variables in the Model Variables page by right-clicking and selecting Paste Variables from Clipboard.
3. Remove and add column header as desired.
4. Select the variables, then click on Create Table button. Alternatively, you can use the right-click menu.
5. Select the cell where the table is going to be added in Excel.
6. The Simulation Workbook Table wizard will appear. Use the wizard to customize the table format.
Keywords: Table, ASW, Organizer,
References: None |
Problem Statement: How to report the mass fraction profile in RadFrac dynamic modeling? | Solution: In Aspen Plus Dynamic modeling, you can report many column profiles by right click on the RadFrac column and choose different forms. For example, you can create liquid/vapor flow profile, liquid/vapor mole fraction profile, temperature and pressure profile, etc.
However, if you click on liquid or vapor mass fraction profile, the profile table is empty.
You will need to go to Simulation Explorer, and open the AllVariables table for the RadFrac column. Then manually change the EvaluateMassFractions option to Yes.
Now you could report mass fraction profile for the RadFrac column.
Keywords: Aspen Plus Dynamics
Radfrac
Mass fraction
References: None |
Problem Statement: How to start using Visual Basic (VB) with InfoPlus.21 | Solution: From the Visual Basic editor within Aspen Process Explorer (APEx), there are two ways to access InfoPlus.21 with Visual Basic:
1. using ODBC/ADO calls, and/or
2. using InfoPlus.21 AtProcessData library
The Infoplus.21 AtProcessData library represents a collection of data sources, each containing a collection of tags, that can retrieve attributes and time series data from configured data sources using Aspen Data Source Architecture (ADSA).
Please find below two easy VB examples. The InfoPlus.21 Application Development Training course covers both methods in depth.
1. Using ODBC/ADO (See any VB manual and the Desktop ODBC User's Guide for more information)
Create a form with a button and a listbox to hold the results of the query
Private Sub CommandButton1_Click()
Dim str As String 'Declare str as the SQL query to pass to adoCon.Execute
str = select name from ip_analogdef where name like 'atc%'
adoCon.Open (SQLplus on localhost) 'This opens the ODBC connection to IP.21
Set adoRecords = adoCon.Execute(str)
Do While Not adoRecords.EOF
ListBox1.AddItem adoRecords!Name 'updates a listbox with the results
adoRecords.MoveNext
Loop
End Sub
2. Using ATProcessData (See the ATProcessData.chm for more information about configuring VB to be able to access InfoPlus.21.)
Create a form with three text-boxes to hold the results of the request.
Next, Under Tools |
Keywords: VB
ProcessData
Automation
VBA
References: s, include the library Aspen Process Data
'Define the special AspenTech datatypes used for the AtProcessData.ocx
Dim mySources As New AtProcessData.DataSources
Dim mySource As AtProcessData.DataSource
Dim myTag As AtProcessData.Tag
Dim myFields As Attributes
Dim myField1 As AtProcessData.Attribute
Dim myField2 As AtProcessData.Attribute
Dim myField3 As AtProcessData.Attribute
Private Sub Get_Attributes()
'Set the datasource
Set mySource = mySources.Item(name_of_the_datasource)
'Connect to the datasource
mySource.Connect
'Set the tag you want to read from, for example ATCAI
Set myTag = mySource.Tags.Add(ATCAI)
'Set attributes fields which will hold the results
Set myFields = myTag.Attributes
'Add the names of the fields you want to read
With myFields
.Add (IP_DESCRIPTION)
.Add (IP_INPUT_VALUE)
.Add (IP_INPUT_TIME)
End With
'Read the data Asynchronously
myFields.Read (False)
'Set (read) the values of the fields
Set myField1 = myFields.Item(IP_DESCRIPTION)
Set myField2 = myFields.Item(IP_INPUT_VALUE)
Set myField3 = myFields.Item(IP_INPUT_TIME)
End Sub
Private Sub Print_Attributes()
TextBox1.Text = myField1.Value
TextBox2.Text = myField2.Value
TextBox3.Text = myField3.Value
End Sub
Private Sub CommandButton1_Click()
Get_Attributes
Print_Attributes
End Sub |
Problem Statement: This | Solution: frames on the limitation that a DMC3 Builder Server has in supporting DMC Online Server.
Solution
Virtually there is no limit on the number of DMC3 Builder can support.
However, The Server CPU and I/O loading considerations are the main factor to considerer in determining how many servers a site may need.
Keywords: DMC3, DMConline
References: None |
Problem Statement: Where can one specify percent over-design in Aspen Shell & Tube Exchanger? | Solution: By default, Aspen Shell & Tube Exchanger will try to design a heat exchanger with an Area Ratio (Actual Area / Required Area) equal to 1.0. Stated another way; Aspen Shell & Tube Exchanger will try to generate a configuration with 0% over-design. It is possible, however, to specify this value as a user input and generate a heat exchanger with required % over-design.
To do this, select Input | Program Options | Design Options | Optimization Options and enter a value for minimum % excess surface area required for heat transfer.
Based on this number, Aspen Shell & Tube Exchanger will come up with a design and reject the designs that do not meet this criterion. You can view the results at Results | Results Summary | Optimization Path. If desired, one can also see the % over-design as an Area Ratio in the Results | Thermal & Hydraulic Summary | Performance | Overall performance page.
Keywords: percent, overdesign, excess, surface area
References: None |
Problem Statement: Why does Aspen HYSYS Workbook not display information from BLOWDOWN flowsheets? | Solution: The BLOWDOWN flowsheet is different than the normal HYSYS flowsheet, not only in terms of solver but also in terms of display and configurations. Streams inside the BLOWDOWN flowsheet do not store any data, hence this is not displayed in the regular HYSYS workbook.
Some of the main data, such as the initial process conditions and compositions are reported and stored in the pipe Unit Operation blocks. This can be extracted using the Aspen HYSYS Reporter (Home tab | Reports).
The user can review key results inside the BLOWDOWN environment, by entering the Results Summary section. The Plot form may be of specific interest since it can be configured to show how various conditions change through the blowdown procedure.
Keywords: Workbook, results, BLOWDOWN, conditions, reporter
References: None |
Problem Statement: How does HYSYS calculate the energy balance around a reactor? | Solution: Basically, the equations used are:
Feed Heat Flow = Hf Feed @ 25C + mCp*Delta T
Product Heat Flow = Hf Prod @ 25C + mCp*DeltaT
(where Hf Feed = Heat of Formation of Feed; Hf Prod = Heat of Formation of Products)
If: Feed Heat Flow = Product Heat Flow
Then:
Hf Feed + Feed(mCp*Delta T) = Hf Prod + Prod(mCp*Delta T)
which gives:
Feed(mCp*Delta T) - (Hf Prod - Hf Feed) = Prod(mCp*Delta T)
which is the same as: Feed(mCp*Delta T) - (heat of reaction) = Prod (mCp*Delta T).
If the reaction is exothermic, then Feed(mCp*DeltaT) + heat of reaction = Prod(mCp*DeltaT) If the reaction is endothermic, then Feed(mCp*DeltaT) - heat of reaction = Prod(mCp*Delta T)
Please refer to the attached HYSYS file and accompanying PDF file for a detailed discussion of the calculations.
Keywords: reactor, heat of reaction, energy balance
References: None |
Problem Statement: Is there a way to change the fouling thickness in Aspen Exchanger Design and Rating (EDR) Shell & Tube Exchanger? | Solution: The fouling thickness can be specified at Input / Program Options / Thermal Analysis / Fouling page.
Keywords: Fouling Thickness, Input warning 1121
References: None |
Problem Statement: Can a user specify excess percent surface area in Aspen Air Cooled Exchanger? | Solution: For an Air Cooler design to be acceptable, its actual surface area must be 100% or more of the required surface area for the specified duty and exchanger size.
Users can now (starting in V10.0) specify at Input | Program Options | Design Options | Optimization Options tab if the criterion is more than 100% (specify the excess over 100%) so that the acceptable Designs effectively has this degree of safety margin.
Keywords: percent, overdesign, excess, surface area
References: None |
Problem Statement: Gas Turbine vendors can provide multiply curves as a specification of the equipment. In Aspen Utilities Planner (AUP) user have 2 options to include specification of Gas Turbine (GT): by using temperature and humidity correction factors, or specifying multiply curves.
When one open Temp Table and Flow Table forms for Gas Turbine there is an option to specify multiply curves, by changing NC_Temp and NC_Flow values. However, in a Heat Table form there is no parameter/ value which can be changed in order to specify multiply curves.
How to specify more than one heat curve in a Heat Table in Gas Turbine model? | Solution: The tables in the Forms were created to simplify inputs, and include some variables related for example to Temp curves, of Heat Curves in separate places.
When creating Heat Curves tables NC_Heat value, which is used to represent number of heat curves was not included in that table. This value can be found in All Variables table.
To open that table, one should right click on the GT model and select Forms-> All Variables. Then the list of All variables which are specified or calculated in this block will be displayed. To change number of Heat Curves one should find the value: NC_Heat and change the value, as shown in the attached screenshot.
User can also add NC_Heat value to the existing Heat Table, by drag and drop the value from All variables table to Heat Table. It can be done only for already created block or for all GT blocks in the file.
To include additional value in all GT blocks in the file, user should modify HeatCurve tables available in the Libraries| Utilities| Fuel_Models| Gas Turbine folder in the simulation explorer.
Keywords: Gas Turbine, multiply Heat Curves, NC_Heat
References: None |
Problem Statement: Aspen HYSYS compatibility issues with OLGA V6.x and higher | Solution: The OLGA software (specifically V6.x) has been completely re-coded and no longer supports the legacy OLGA Server. OLGA 6 uses an OPC interface, while OLGA 5 uses a specialized tcp/ip interface. Also a new OPC based server functionality was included and released in OLGA 6.2.6. But this is not tested with HYSYS-OLGA link.
If OLGA HYSYS link doesn't work on OLGA 6, you can try the following:
1. The most secure and warranted way is still to use older version of OLGA, i.e. OLGA v5.3.2. On V6 OLGA install, V5.3.2 OLGA executable is also installed to support the server commands. So if you choose a V6 executable in Aspen HYSYS, you may have problems. In the OLGA executable field on the Setup|Server tab, try selecting the OLGA V5.3.2.exe executable in the OlgaExecutables_5_3_2 directory that was installed.
2. If you would like to use OLGA 6, download the latest version OLGA 6.2.7/ V6.3 onwards- which has a new function OPC Server. By the new function, you can make the OLGA output variables visible through OPC Server and further connect them to HYSYS or other simulator.
In short, you can try to see if the OLGA server link works in 6.2.6 or 6.3 OR otherwise link to the v5.3.2 executable for the HYSYS OLGA Link (if available along with 6.2.6 or 6.3 install or download separately from the SPT website)
Note: Aspen HYSYS currently does not support OLGA ver 6 or 7. HYSYS development team will consider this in a higher version. Unfortunately, this has not been finalized yet.
May 2018 Update: A new OLGA link allows engineers to use the latest versions of OLGA with Aspen HYSYS V9 and V10. Please see https://esupport.aspentech.com/S_Article?id=000046771 for more information.
Keywords: OLGA, HYSYS, Link
References: None |
Problem Statement: The reported vapor fraction for the inlet stream to a fire-sized PSV is 1.0, even though it is supposed to be a V-L mixture. Why? | Solution: Whenever the relieving flow method for a fire-sized PSV is ‘Calculated’ when using the (API) Wetted calculation method, the Fire scenario reference stream will be taken to its bubble point and then the bubble point vapor will be the material to be relieved.
Therefore, the reported vapor fraction (Vf) of the fluid for the inlet stream (on the ‘Line Sizing’ form, provided that the ‘Fire’ scenario is set as the sizing case) to the PSV will be reported as 1.0 (Vf=1.0, full vapor), even though the true inlet fluid might be a V-L mixture.
On the other hand, when the relieving flow method is set to either ‘Manual’ or ‘
Keywords: PSV, Relieving Flow Method, Relieving Calculation Method, Fire Case, Vapor Fraction, Calculated, Manual,
References: ’, then the entire scenario reference stream will be relieved.
Therefore, the reported vapor fraction at the PSV inlet will be reported as 0.0<Vf<=1.0.
Of course, compositions will be different in each case. |
Problem Statement: How to modify Aspen HYSYS case built with oil characterization to open case without crude license error message | Solution: According to Article ID 30633, one of the reasons users will receive a crude license error message is when using the Oil environment.
The workaround is to delete all the hypo components in the simulation basis created by the Oil Manager. The hypo components created by the Oil Manager have IDs starting from 10000 and those created from the component list (i.e., normal hypo components) have IDs starting from 20000. The component ID number can be viewed by Double on the Hypo Component itself. The ID number is located under the ID tab. See a screenshot below for an oil manager created hypo component.
Keywords: Oil environment, Hypo components, Not Licensed for Crude Distillation
References: None |
Problem Statement: What does Modify Tc, Pc for H2, He option in some equation of state fluid packages imply? | Solution: In Aspen HYSYS, when you choose some commonly used equation of state fluid packages (like Peng-Robinson, SRK or Sour PR), you will see the default option to Modify Tc, Pc for H2, He.
The default option Modify Tc, Pc for H2 and He uses a proprietary function to evaluate critical properties as a function of the actual temperature. This feature produces better results for simulation systems containing H2 and He. If you click on the drop down list, the other option you can use is “Unmodified Modify Tc, Pc for H2, He”, and this will use the fixed literature values, with no dependence on temperature.
You may wonder why critical temperature and pressure could be evaluated as a function of the actual temperature. Yes, in reality, Tc and Pc are fixed values for a certain component, independent of the actual temperature. In Peng-Robinson equation, the equation parameters a and b are calculated using Tc and Pc (you could find the detailed calculation methods in HYSYS help menu).
However, Peng-Robinson equation (and other equation of states like SRK and Sour PR) has a latent flaw that it predicts a universal critical compressibility factor (Zc) for every fluid, which is 0.3074. Therefore, if you use fixed Tc and Pc to calculate a and b in the equation, you may lose some precision. And that it is why we have the option here to evaluate Tc and Pc as a function of the actual temperature. It is only for EOS calculation.
Keywords: Equation of state, Peng-Robinson,Critical temperature,Critical pressure,He, H2
References: None |
Problem Statement: There seems to be a reporting discrepancy on construction rental equipment costs. Equipment rental shows up on two different reports with two different values. The two reports are both Standard reports under Indirect Costs: Project Indirect Summary and Overall Equipment Rental Summary. What is the reason for this discrepancy and how can this be fixed? | Solution: The reason you might be getting different values in the two reports is likely due to entering Rental Equipment specs (as shown in attached screenshot) in the Contractors form or through the External Indirects file. The Overall Equipment Summary Rental will only provide the details for actual equipment being used.
Keywords: Equipment Rental, contractor indirects
References: None |
Problem Statement: How to check the crossflow fraction of the shell & tube heat exchanger? | Solution: In the figure above, only the crossflow stream B (and part of the window flow) contribute to the heat transfer.
Stream A is the primary leakage stream and passes through the shell ID to bundle OTL diametric clearance. It can significantly decrease the pressure drop and will also reduce the film coefficient.
Flow E is a second leakage stream going through the baffle OD to shell ID diametric clearance.
Flow C is called a bypass stream in the shell ID to bundle OTL diametric clearance. It bypasses the heat transfer surface.
Flow F is a bypass flow in in-line pass partition lanes.
You can go to the Results - Thermal/Hydraulic Summary - Flow Analysis to crossflow fractions of your shell & tube heat exchanger.
The crossflow fraction usually ranges from 30-70 % of the total flow. Lower values will give lower pressure drops, but generally indicate a poor design.
Keywords: Crossflow
Heat transfer
Pressure drops
References: None |
Problem Statement: What is Liquid Residence Time Factor in a 3 phase real separator? | Solution: Liquid residence time factor is a tuning parameter which is used to adjust the carry over result closer to the reality data. The default value for this parameter is 1. When a higher value is specified, the separation between vapour (V) and light liquid (LL) is better. Please see an illustrative chart as shown below:
As shown in the chart, higher liquid residence time factor gives better separation between V and LL, which is getting closer to the ideal 3-phase separator.
Keywords: Liquid residence time factor, 3-phase real separator
References: None |
Problem Statement: Can you provide more information about units of measurement display in Aspen Plus for Aspen Custom Modeler (ACM) models?
For example why do I get a * character displayed instead of my custom units? | Solution: You will get a * rather than a unit in Aspen Plus if:
there is no mapping from your variable type to the Aspen Plus units table
your ACM variable's variable type has no physical quantity
In the first case, you can fix it like this:
In the OnNewDocumentScript.vb file, when you add a physical quantity the last two numbers passed in are the row number of the corresponding entry in the Aspen Plus units table (units.dat or rcunits.dat) and the Aspen Plus column number corresponding to the ACM base unit for the quantity. So in the example below the ACM internal base unit for a MassHeatCapacity corresponds to the 6th conversion defined for row 49 in the Aspen Plus table.
'*** MassHeatCapacity ***
bOK = UOM.AddPhysicalQuantity(MassHeatCapacity, kJ/kg/K, 49, 6)
If these numbers are left out like this:
'*** MolarHeatCapacity ***
bOK = UOM.AddPhysicalQuantity(MolarHeatCapacity, kJ/kmol/K)
then it means there is no correspondence with Aspen Plus so Aspen Plus won't be able to do UOM conversions and you will get a * in the units column for a molarheatcapacity variable.
If the correspondence is correctly defined then you should be able to convert values in Aspen Plus without problems and it should not matter what display units you use in ACM.
Say for example that you have added to ACM 1/s unit in the current OnNewDocumentScript.vb, i.e. Inverse_time physical quantity to ACM. You should then define it like this to get conversions to work in Aspen Plus
bOK = UOM.AddPhysicalQuantity(Inverse_time,1/sec,59,1)
This makes the base unit in ACM 1/sec which is the same as the Aspen Plus base unit (hence 1 for the Aspen Plus column number).
If you are adding a new physical quantity that corresponds to an Aspen Plus physical quantity then it makes sense to make your ACM UOM symbols for the quantity identical to those used in Aspen Plus to avoid matching problems. That's why we used 1/sec in the example above.
Keywords: model export, units, physicalquantity
References: None |
Problem Statement: How can I get the higher and lower heating values in units of BTU/ft3? | Solution: Currently the default units in HYSYS for the higher and lower heating properties do not include BTU/ft3. To use these units you must create a user unit conversion, as described in the steps below:
1. Select the Home Tab and click Units Sets from the Units section or Click in File/Options/units of Measure.
2. From the list of Display Units scroll down until you find Volume Specific Energy.
5. Click the Add button.
6. In the User Conversion window provide the name for your user unit and specify a conversion rate of 26.85 * MJ/m3. If you want to edit the unit click in View and correct the conversion rate.
Note that the volume is specified at standard conditions. For Metric these are 1 atm and 15C; for Imperial these are 1 atm and 60F.
Keywords: Lower Heating Value, Higher Heating Value, Heating Value, change unit, create unit
References: None |
Problem Statement: How does the Tube Rupture scenario in the Safety Analysis Environment calculate critical flow pressure? | Solution: The Tube Rupture calculation in the Safety Analysis Environment uses the Ideal Gas equation of state for critical flow pressure:
Where:
Pc = Critical Flow Pressure
Po = Relieving Pressure at the Low-Pressure Side
k = Rate of Specific Heats
Following the guidance of the paper PRV sizing for exchanger tube rupture by Wing Y. Wong which was published in ‘Hydrocarbon Processing’ in February
1992.
In the case of a two-phase, this is used as the overall choke using the ideal ‘k’ for the vapor portion of the stream only.
Keywords: Tube Rupture, Critical Pressure, Choked Flow.
References: None |
Problem Statement: What should I do when HYSYS predicts two liquid phases for my stream (containing hydrocarbons) which I know for sure contains only a single liquid phase? | Solution: There are a few things that you could do to get around this problem:
You could make change to Stability Test to approach theSolution on a different route. In this case, since we know for certain that there is only one phase, you can switch the flash method to HYSIM Flash instead of the default HYSYS Low.
Follow these steps: In Properties environment > Fluid Package form > Click on the current fluid package > Select StabTest > Adjust the method under Stability Test Parameters. HYSIM Flash performs less rigorous flash calculations, and thus won’t find the second phase.
Note: you should be careful when using HYSIM Flash as the method does not do stability test.
Another factor to consider is the binary interaction coefficient. If you have better binary interaction data for your system, you could overwrite the data defaulted on the Binary Coeffs Tab.
Keywords: oil; two liquid phases; false phase splitting;
References: None |
Problem Statement: How to view the true vapor pressure of a stream | Solution: If not shown, you can add the true vapor pressure to Stream / Properties. Click Append new correlation (the green cross in the bottom).
In the Correlation Picker window, under Standard, apply True VP at 37.8 C.
After that, the true vapor pressure will be reported in the Properties of that stream. You can use this method to report any other properties of a material stream.
Keywords: True vapor pressure
Properties
Append new correlation
References: None |
Problem Statement: How many increments / elements are used in a pipe in Aspen Flare System Analyzer? How can I change it? | Solution: Increments in a pipe in Aspen HYSYS is called elements in a pipe in Aspen Flare System Analyzer. By default 10 elements are used in a pipe.
To change the number of elements for all the pipes, go to Calculations Settings Editor || Methods Tab || change the number of Elements.
To change the number of elements in a particular pipe, double click on the Pipe Editor || Methods tab || provide the number of Elements.
Keywords: Elements, increments, segments
References: None |
Problem Statement: Is it possible to automate importing CSV files into the data source in Mtell? | Solution: Ensure you have a CSV Sensor Data Source created and an appropriate file format configured for this data source.
On Mtell Server V4.3, navigate to C:\Program Files\Mtell\Mtell Agent Service\CSV (on V10 this is C:\Program Files\AspenTech\Aspen Mtell\Mtell Agent Service\CSV) and copy the CSV files to import into the TagImport folder.
Please make sure of the following properties about the file- a) It should be of the same format as specified for the CSV data source b) Ensure the CSV file is not marked as Read Only.
Make sure you have an Agent Service connecting to the appropriate Mtell Service. Start Agent Services.
On every execution of the Agent, the system imports the CSV file.
When the file is imported, it is automatically moved from the TagImport folder to the TagProcessed folder.
File system automation of moving the CSV file to the appropriate location (listed below) has to be done by the user. You can automate this process using either powershell or cmdline scripts. Once the CSV file is in this location, it is imported by the system into the database.
Keywords: Automate Data import
Sensor Data
References: None |
Problem Statement: Where do I find additional documentation for Administration and Configuration help? | Solution: ABE includes a folder with documentation. Some of those guides includes information about Administrator tasks and ABE Query Editor script references.
The folder's default location is:
C:\Program Files\AspenTech\Basic Engineering VX.X\UserServices\Help
Keywords: Documentation, getting started, reference guides
References: None |
Problem Statement: I have some old Access file (.mdb) from PSV Plus before it was acquired by AspenTech. Could I still apply them in Aspen HYSYS Safety Analysis? | Solution: If you have the Access file (.mdb) from PSV Plus, you could use the Conversion Tool to open it in HYSYS v.8.8 Safety Analysis.
In the Safety Analysis environment, click Customize tab, click and open the hided PSV Plus Conversion Tool:
In the PSV Plus to Aspen Hysys Conversion Utility, enter the name of the Access file (.mdb) you wish to import, or browse the file location. Then click the Connect tab.
Keywords: PSV Plus
mdb file
Safety Analysis
References: None |
Problem Statement: Is there any other way to set a case besides going into each individual field's properties and set the case? | Solution: You can select all the fields, e.g. an entire column or row, and using the Edit | Case option from the Datasheets menu, define the case for all the fields at once.
For V10, use the Cases button to select the appropriate case.
Keywords: Datasheet Definer, multi-selection
References: None |
Problem Statement: What is a *.WWB extension file and how do I use it? | Solution: In Aspen HYSYS, the *.WWB extension file is a WinWrap Basic automation script that you write and execute with the Aspen HYSYS Macro Language editor.
If the you want to open the *.wwb file, please follow these steps:
1. In the Customize Tab, select Macro Language Editor command from the Tools menu.
2. The Aspen HYSYS Macro Language Editor property view appears. Right-click anywhere on the Macro Language Editor property view, and select File | Open command from the Object Inspect menu.
3. In the Open property view, select the WinWrap Basic (*.WWB) file to open.
Keywords: Macro Language Editor, wwb, customization, automation, script
References: None |
Problem Statement: The zoom slider does not seem to be working for the time-based charts in AFR (capacity over time, pipe flow etc.). Is there another way to zoom-in for those charts? | Solution: The zoom slider in the bottom right corner works only for the flowsheet. Starting with AFR V10 CP4 (10.0.4), the zoom functionality has been added for all time based results. It only applies to the main graph and does not apply to the Lifecycle and ReSolution Step charts. Following are the steps to zoom-in and zoom-out:
Zoom-in:
1. Left-click and hold
2. Drag the cursor to the right and select the area you want to zoom
3. Release the left mouse button
You must drag the cursor to the right to zoom in.
Zoom-out:
1. Left-click and hold
2. Drag the cursor to the left to zoom out
3. Release the left mouse button
You must drag the cursor to the left to zoom out.
The attached screenshots explain the zoom functionality in greater detail.
Note: You can also reset zoom to 100% by right-clicking on the graph.
Keywords: zoom, time-based charts
References: None |
Problem Statement: Why do some streams have the @ symbol before the name? | Solution: Streams with the @ symbol originate from a flowsheet that is different than the one you are currently in. Example: If you are building a controller in the Main Flowsheet and the process variable you require is an internal stream in the Column SubFlowsheet (T100), then the process variable will appear as Stream1@T100.
Keywords: streams symbol, streams, streams name
References: None |
Problem Statement: What methods are used to calculate the True and Pseudo Critical Properties ? | Solution: The true critical properties are the real critical properties of the stream determined thermodynamically by satisfying both the quadratic and cubic forms of the expansion of the Helmholtz free energy as a function of the mole numbers at a critical point.
[Details of this method can be found in the paper by Heidemann and Khalil (AIChE Journal, Vol. 26, No.5, p769-779, 1980).]
The pseudo critical properties of a stream are determined based on the critical properties of its constituent components. These are summed together weighted by the component mole fractions.
For example, an equal-molar mixture of nitrogen (Tc=-146.96C) and ethane(Tc=32.28C) has a pseudo Tpc = 0.5*(-146.96) + 0.5*32.28 = -57.34C.
Keywords: Critical Propertes Utility, Heidemann and Khalil method
References: None |
Problem Statement: Why do I see discontinuity in the liquid density vs. temperature curve? | Solution: Density can be calculated by two methods: Costald correlation for pure liquid or Equation of State (EOS). Costald correlation provides high accurate result, especially for saturated pure liquids. Because Costald correlation was designed for saturated liquids, it is not applicable when temperature is at the critical point and beyond. From this reduced temperature unity point, Aspen HYSYS will switch to EOS method to calculate density. This switching point causes a discontinuity as you have observed.
From Aspen HYSYS V3.0 onward, Smooth Liquid Density option is included. When this option is enabled, density will be interpolated between Tr = 0.95 to Tr = 1 to create a smooth transition from Costald correlation to EOS method.
Alternatively, you can also avoid curve discontinuity by using EOS as the single calculation method. To follow this route:
In Properties environment > Select Fluid Packages page > Select a suitable fluid package
On the Options section > Density > From drop down menu, select Use EOS Density instead of Costald as the default method
This option is available only on some fluid packages, such as PR, SRK, and etc.
On the side note, HYSYS calculates other properties of a stream in supercritical region by assuming a phase. Technically, vapor and liquid phase are indistinguishable in supercritical region. HYSYS, however, assigns a phase for flash calculation purpose - This phase designation is based on compressibility factor and isothermal compressibility factor. Hence, the vapor fraction observed in this region (either 1 or 0) does not hold any physical meaning.
Keywords: liquid density, COSTALD method, discontinuity, smooth density curve
References: None |
Problem Statement: What does Flame height lower than vessel elevation. No fire load generated message mean? | Solution: When running a Fire scenario in Safety Analysis, the message Flame height lower than vessel elevation. No fire load generated can appear.
According to API 521 6e (2014), any area higher than 25 ft is not subject to fire, so if the specified elevation of the vessel (or one of the vessels) is equal or higher than 25 ft, the relieve load will be zero.
Keywords: Flame height, elevation, fire scenario, API
References: None |
Problem Statement: Is MABP for relief valve based on static pressure or total pressure? Should I use static pressure or total pressure to check it? | Solution: By default, MABP violation warning is based on static pressure. The user should use static pressure ONLY, but Aspen Flare System Analyzer gives the user an option to change if the user does not agree.
As mentioned in theSolution 000032086, the Total pressure is sum of the Static head and Velocity head.
Backpressure in Flare systems are considered in static pressure. If the relief valve MAWP is 10 barg then MABP for a conventional valve is 1 barg, the velocity head does not come into the equation at all.
If the velocity of the gas causes a velocity head of 0.3 barg then even though the Total BP is shown as 1.3 barg the valve will still pass the required flow at design conditions. The size of the pipe downstream will affect the static built up backpressure. Static pressure acts in all directions, velocity head acts in the direction of flow.
The best reference we can come up with is the following one:
Clancy, L.J. (1975), Aerodynamics, Pitman Publishing Limited, London ISBN 0 273 01120 0
In Aerodynamics, L.J. Clancy writes: To distinguish it from the total and dynamic pressures, the actual pressure of the fluid, which is associated not with its motion but with its state, is often referred to as the static pressure, but where the term pressure alone is used it refers to this static pressure.
Properties of a fluid are associated with the state of the fluid, not the motion of the fluid, hence you should use the static pressure of the fluid to calculate its properties.
Note:
Attached is presentation that explains a bit more about the static Vs total pressure issue.
The static head is independent of velocity and flow rate at any point in flow network. For a constant geometry (pipe diameter), no frictional losses and no elevation change, there is no static pressure drop.
The total pressure head is sum of static and velocity head. When the velocity is close to zero (due to very large pipe size) then the total pressure is close to static pressure.
On the PFD, if the user wants to view the total pressure NOT static pressure, then go to the File | Preferences | General Tab, and check the box for Display Total Pressure.
If the user wants to get the relief valve MABP violation based on total pressure, not static pressure, then click on Calculation Settings | Warnings Tab and select Total Pressure in the Back pressure warning on.
Keywords: Total, Pressure, Static Pressure, MABP
References: None |
Problem Statement: Which property package should I use for supercritical region and dense fluid hydrocarbon? | Solution: The best method to use would be an Equation of state such as Peng-Robinson.
To emphasize on this matter, since an equation of state (EOS) should be used to calculate both liquid and vapor properties, it does not matter what phase the stream has assigned to it. Activity coefficient (phi/gamma) models should not be used for supercritical mixtures since the vapor and liquid calculations are inconsistent in the critical range.
Normally we recommend the HYSYS Peng-Robinson EOS model for most oil and gas applications. This model has modified and optimized from the standard PR EOS to better match actual data. PR is applicable from low pressure up to pressures of 1000 bar. This property model can also be used to simulate supercritical (dense phase) fluids.
Note that HYSYS reports a vapor fraction for a stream under supercritical conditions as zero or one. Theoretically, this value does not have a specific physical meaning since there are no distinct liquid and vapor phases in a supercritical region. However, for the purpose of flash calculations, HYSYS will determine the vapor fraction of a dense-phase stream based on the following criteria:
If the compressibility factor (Z) is less than 0.3 and the isothermal compressibility factor (beta) is less than 0.1/P, a vapor fraction of zero (Vf=0) is assigned to the stream, otherwise the vapor fraction would be one (Vf=1). If the vapor fraction for a supercritical fluid equals one (Vf=1), vapor correlations are used for the physical property calculations, otherwise liquid correlations would be used.
To summarize, the vapor fraction for a dense-phase stream is not an indication of its phase state (liquid/vapor), but only an indication of which correlations (liquid or vapor) are used for the stream properties. In order to identify when a fluid becomes supercritical, it is usually advisable to use the envelope utility, although the critical properties utility can also be used for this purpose.
Keywords: Aspen HYSYS, PR, Supercritical, Method
References: None |
Problem Statement: After importing stream data from PRO/II into ABE, even though the stream is either full vapor or liquid, zeroes are shown for all attributes for the non-existing phase. Why? | Solution: Due to the way ABE maps PRO/II objects to ABE objects, in the case that imported streams from PRO/II had a vapor fraction of either 0.0 or 1.0, zeroes will be assigned to all attributes for the non-existing phase, since PRO/II internally assigns such values to the non-existing vapor or liquid phase when the system is full liquid or vapor, respectively.
The image below illustrates the case of a full vapor stream imported from PRO/II into ABE. Zero is the assigned value for all liquid phase attributes.
Keywords: PRO/II, Data Import, Stream, Vapor, Liquid, Attributes, Zero, Simulation Import
References: None |
Problem Statement: How to migrate Aspen Properties Enterprise Database from SQL Express to a Central SQL Server. | Solution: aspenONE Engineering products will use Aspen Properties Enterprise Database (APED) which can be hosted on SQLLocalDB or SQL Server Express on local machine or on Central SQL Server Database. If customer has initially hosted the database on SQL Express locally on user machine and wants to migrate to Central SQL Server Database then please follow thisSolution article.
Setup Aspen Properties Database on Central SQL Server:
Please follow KBSolution 145154 to setup Central SQL Server
Setup User machine with registry key to disallow local APED database:
a. A registry entry needs to be created before installing any Aspen Products on the Citrix machine to allow remote Aspen Properties Database only.
b. The following entries needs to be created on the users machine:
64- Bit Machine:
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\AspenTech\APED\xx.0]
ASPENDB=dword:00000002
Note: xx means the build number for Aspen Products. Example: 34.0 is a build number for V8.8
32-bit Machine:
[HKEY_LOCAL_MACHINE\SOFTWARE\AspenTech\APED\xx.0]
ASPENDB=dword:00000002
Note: xx means the build number for Aspen Products. Example: 34.0 is a build number for V8.8
Configure the user machine to connect Aspen Properties Database on Central SQL Server:
a. Go to Start | All Programs | AspenTech | Process Modeling V10.x | Aspen Properties | Aspen Properties Database Manager. Click OK.
In the Aspen Properties Database Manager, on the left side, right-click on Aspen Physical Properties Databases and select Register Database
At the Register Properties Database Wizard, fill in the following information:
Uncheck Use LocalDB
<SQL Server Service Path>Server Name: (Note: The default is .\SQLEXPRESS. The “.\” means “this computer”. If connecting to another computer, put the computer’s name first, followed by the SQL Server Service name. Example: Server1\SQLEXPRESS)
Authentication Mode: Select SQL Authentication. (Note: login credentials should be used which has SYSADMIN rights on Central SQL Server. The below login credentials are the default for APED database which would need to be created on Central SQL Server if not available after restoring the Database)
Login Name: apeduser (v7.0-7.3) or apeduser2 (v8.x)
Password: Aprop100 (v7.0-7.3) or Aproperty88# (v8.x)
Database: Select the Database listed in the list of Database Example: APEOSv8.x, APV8x, NISTV8x and FACTV8x
Click Ok
Repeat step 1 – 7 for all APEOSv8.x, APV8x, NISTV8x and FACTV8x databases.
Exit Aspen Properties Database Manager.
Config.aem file will get updated with registered database.
Keywords: Centralize
APED
Share
Remote Connection
Database
References: None |
Problem Statement: Is it possible to add alternative names and CAS number for a component in a user properties databank? | Solution: To add parameters to an Aspen Properties Enterprise Database (APED) databank, you can use an Aspen DFMS input file (.inp). To add CAS number, you can use an Aspen MMTBS file (.dat). To add alternate name, you can use a .dat file called Synonyms.dat. Attached is an example for Methane (CH4), including
1) The legacy DFMS input file with the property parameters, dbch4.inp.
2) The MMTBS input file, dbch4.dat. This file starts with the first line as DBANK ADD DBCH4 where DBCH4 is the databank name defined in the DFMS input file. there are three lines for each component,
Alias Name Charge
MW TB, VLSTD
CAS number Comp-class
All parameters are in SI units. Here are values for CH4 in dbch4.dat:
CH4 METHANE 0
16.0425 111.660 0.535578E-01
74-82-8 n-Alkanes
You can use * if you don't know the value for a parameter.
3) In Synonyms.dat, each component has the following entry:
SYNONYMS ADD CH4
4
FIRE DAMP
MARSH GAS
METHYL HYDRIDE
REFRIGERANT 50
In this example, CH4 has four alternate names (or synonyms).
When you import these files, you need to import them in the following order:
dbch4.inp
dbch4.dat
Synonyms.dat
SeeSolution 25970 for more information on how to create an APED databank from legacy files.
Keywords: APED
create databank
VSTS 24151
References: None |
Problem Statement: What property package do I use for an ammonia-water system at low pressure? | Solution: In the presence of an aqueous phase, the Sour PR or Sour SRK property package is usually recommended. These models are suitable for these conditions: 20 C - 140 C, up to 50 psi, < 65 wt % ammonia. Sour PR performs well with water partial pressure below 100 psi. User can also refer to F1 Help Menu for more details of each property package.
Keywords: Ammonia, NH3, water, aqueous, Sour,
References: None |
Problem Statement: When attempting to run Aspen Plus Dynamics with Simulink (MCH.mdl example) the run fails with the following message:
Error evaluating 'LoadFcn' callback of M-S-Function block 'MCH/MCH Column
(Aspen Dynamics)'.
Caused by:
Server Creation Failed: Class not registered | Solution: When attempting to create a link between Matlab and Aspen Plus Dynamics, ensure that the Matlab version installed is 32-bit. Aspen Plus Dynamics is a 32-bit application and will not interface with a 64-bit program. The interface between Matlab and Aspen Plus Dynamics is created by Simulink. A file called AMSimulink is automatically copied into the Matlab working directory, users must have write access to this directory.
The Aspen Plus Dynamics Help contains instructions on how to run a library case, MCH.mdl, to test the connection between Matlab and Aspen Plus Dynamics using Simulink.
If at the point of attempting to run this, or any other, Matlab model and the following error message is received:
Error evaluating 'LoadFcn' callback of M-S-Function block 'MCH/MCH Column
(Aspen Dynamics)'.
Caused by:
Server Creation Failed: Class not registered
It means that the AMSimulink file may need to be re-registered. To re-register, run the cmd prompt window as Administrator (right-click Command Prompt and Run as Administrator), then type the following inside the window:
regasm /codebase C:\Program Files (x86)\AspenTech\AMSystem V10.0\Bin\AMSimulink.dll
This is for Aspen Plus Dynamics V10. For V9.0 or any other version, ensure the correct path to the AMSimulink deliverable directory (AMSystem), is set correctly.
If the following message is returned from the regasm command:
'regasm' is not recognized as an internal or external command,
operable program or batch file.
This means that the path containing the regasm.exe file has not been set. To set this path, first identify the latest Microsoft.Net Framework version (C:\Windows\Microsoft.NET\Framework), for Aspen Engineering products V9 and V10.0 the most likely version is v4.0.30319. Double check just to be sure.
Next, return to the command prompt window, you can launch a new instance but it is not required, and then type the following command:
C:\Windows\Microsoft.NET\Framework\v4.0.30319> regasm /codebase C:\Program Files (x86)\AspenTech\AMSystem V10.0\Bin\AMSimulink.dll
This ensures that a path is set to the regasm executable and this is required to register the Simulink dll.
Keywords: Aspen Dynamics and Matlab, AMSimulink, AMSimulation, regasm
References: None |
Problem Statement: Does HYSYS take into consideration the heat transfer from the air to the vessel? | Solution: At present no, the only energy transfer is from the mass of the vessel to the fluid.
Keywords: Vessel Heat Transfer.
References: None |
Problem Statement: I have set a zero-flow spec upstream of my valve and fully closed it, but the flow out is not zero. Why? | Solution: In Aspen HYSYS, the flow through valves is constant at Steady State, but if in Dynamic mode a non-zero flow is specified and enforced upstream of the valve (i.e. by setting a flow spec), the flow out of the valve will not be zero even if the valve is fully closed because the ‘Cv’ parameter will not be used. The only way to use the ‘Cv’ parameter along with the valve opening is to specify the pressure upstream of the valve, in other words, to set a pressure spec upstream of the valve rather than a flow spec.
Specifying a zero-flow value is never recommended because, even though there are max/min flow clamps, this would take the simulation close to a boundary condition, which would start causing problems. On the other hand, changing the flow value instantaneously from a high flow rate value to zero-flow (for example, from 1,000 kg/hr to 0 kg/hr) will further destabilize the dynamic model.
However, if users still want to use a flow spec on the valve inlet and to further change it to zero-flow, a good tip is to use the event scheduler to ramp down the flow instead of instantaneously changing it to zero. For example, if the current flow rate is 1,000 kg/hr and the flow is to be set to 0 kg/hr, ramp it down from 1,000 kg/hr -> 700 kg/hr -> 400 kg/hr -> 200 kg/hr -> 0.01 kg/hr -> 0 kg/hr (does not have to be those values or even those many steps, just something between 1,000 kg/hr and 0 kg/hr).
To learn more about the Event Scheduler feature in Aspen HYSYS Dynamics, please consult the following Articles:
000038093 - 'Application example of the Event Scheduler'.
000038452 - 'Event Scheduler Demonstration Model'.
000014175 - 'How to manipulate the Controller mode using the Event Scheduler'.
Keywords: Valve, Dynamics, Cv, Zero-Flow, Flow Spec, Pressure Spec, Event Scheduler.
References: None |
Problem Statement: Why has the controller given up on my CV(s)? | Solution: The controller gives up on certain CV(s) because there is no feasibleSolution of the current set of limits. The tunings tell the controller that this is a least important CV to give up on (check CV ranks).
Use Aspen Watch control objective function to determine which CV is more important than this CV.
Use your process know-how in order to come up with proper ranks for different CVs.
Keywords: Controller, CV, Tuning
References: None |
Problem Statement: What is the best practice recommendation for cimio configuration of Aspen APC to Honeywell DCS? | Solution: The following recommendations can be used for cimio configuration of Aspen APC Server to Honeywell OPC.
1) There are two ways to connect using cimio for opc for Aspen APC to Honeywell OPC server. Select one of the two options below -
Option a) is to install cimio for opc on the OPC server
Option b) is to install cimio for opc on the APC server and the following setting is needed -
2) If option b) is selected then the DCOM settings to be used for this configuration should follow the protocol of OPC as shown in attached pdf document (include anonymous and everyone user group as recommended in page 5 of 8 of the document).
3) APC connects to Honeywell OPC in an asynchronous manner for both read and write. Hence Synchronous read and synchronous write should be left unchecked in the cimio properties page -
4) An additional step to check if you are using DMC3 Builder (RTE based controller deployment) - Verify if the float entries in Honeywell OPC is single float or double and match the variable entry in DMC3 Builder application to be Single or Double.
5) LISTSZ of application is recommended to be 420 or lesser for Cimio communication to Honeywell EAPP based OPC servers (https://esupport.aspentech.com/S_Article?id=000044755)
6) CimIO diagnostics logging is not required to be run continuously and is only meant for capturing specific errors in a short period of time. If CimIO diagnostics logging is running and if it is generating a cimio diagnostic log on a continuous day to day basis then it is recommended to stop the diagnostic logging (turning it to disable) and restart the cimio manager service to take this change in diagnostic configuration into effect. It is recommended to plan this activity as it could affect any running applications.
NOTE - Additional reading material
https://esupport.aspentech.com/S_Article?id=000015319
https://esupport.aspentech.com/S_Article?id=000014898
https://esupport.aspentech.com/S_Article?id=000027190
https://esupport.aspentech.com/S_Article?id=000015465
https://esupport.aspentech.com/S_Article?id=000015217
Keywords: Honeywell OPC
LISTSZ
References: None |
Problem Statement: I'm trying to model a scenario in HYSYS dynamics in which a control valve closes or opens within a specified time. Is there a method of simulating this event? | Solution: The Ramp Controller option in Event Scheduler can only ramp the SP of the controller. But in this case, we need to ramp the real open percentage of the vale directly. We use Transfer function to do this job.
In the attached example, there is a Transfer function block in HYSYS Dynamics to open valve VLV-102 from 0% to 100% within 50 minutes.
A valve opening percentage is used directly as the Transfer function's OP, instead of manipulating it through desirable actuator position.
To run the file, you will need to start the integrator and click the Start Ramp button in the Transfer function block as well. Then you will see the valve VLV-102 opening from 0% to 100% within 50 minutes time.
Keywords: ramp, valve, ramp duration, Transfer function, percentage open
References: None |
Problem Statement: How can I include the results on the Electrolytes page of a stream on the HYSYS Workbook? | Solution: The key to add all the results under Electrolytes | Properties is simply to know the variable name associated to these values.
The table below shows the variable name which can be used in HYSYS to report this values in the HYSYS workbook or even in PFD tables.
Variable in Electrolytes page Variable name for Workbook
pH pHValue
Osmotic Pressure Osmotic Pressure – Aqueous
Ionic Strength Ionic Strength – Aqueous
Heat Capacity Heat Capacity – Aqueous
Viscosity Viscosity – Aqueous
Please note that only the Properties reported in the Electrolyte page have an associated variable to take into the Workbook or a PFD table.
The Composition data is not associated to a specific HYSYS variable and as such, can only be reported in a Data Table by copying and pasting and pasting these values. A Data Table can then be exported to Excel or placed in the flowsheet as needed.
Keywords: OLI, Viscosity, pH, Heat capacity, Ion, Electrolyte, Property, Workbook, PFD, Table, Data, Report
References: None |
Problem Statement: How do I create a new drawing type? | Solution: We have different drawing types e.g. PFD and PPID diagram types but based on your requirement, you can customize new drawing types. The basic steps are listed below, which you can use as guideline.
Create a new diagram class
1. Launch Class Library Editor, and open the library that you are using.
2. From Insert Menu, click 'Insert Class' to add a new class, enter a name for the new class, eg. 'PFD2'.
3. Add the description, if you want.Under the Superclasses box, insert 'DrawingTemplate' Click OK. Make sure the new class is added.
4. Open 'PFD2' class, insert an attribute in the class. Enter the name of the attribute: 'SheetSize'; Default Value: 'isoA3Tall'. Click OK.
5. Compile the library to make a class store. Reload the workspace.
Define the symbol library and Symbol Map
1. Launch Drawing Editor, and login a workspace.
2. Do not open any diagram. Go to File --> Drawing Templates... the Edit Drawing Template diagram pops up.
3. Go to the Templates drop-down list, make sure PFD2 is listed there.
4.Select PFD2 from the list, and click 'Edit' button. The Open Template File window pops up.
5.Go to 'Template' under 'WorkspaceLibraries'. Enter PFD2 in the File name combo-box and click Open. The Edit Symbol Library and Symbol Maps window pops up.
6.Go to Symbol Library. The left column is Physical Folder, Symbols folder under it. Double click it. All the physical symbol folders will be expanded. (Those hidden folders will not be listed there). The right column is Logical Folder, PFD2 folder is listed. But it is empty.
7.Use Drag and drop method to copy all folders under Symbols to PFD2. Double click the PFD2 folder to make sure the same folders there. You can go to 'Template' folder and copy the 'PFD.xml' file and paste it with 'PFD2.xml' name. For more information refer toSolution How do I include a new folder in the Symbol Library displayed in the Drawing Editor?
8. Finally, in Drawing Editor, click 'New', and enter the name of the diagram and select PFD2 as the Diagram Type. Click OK. New diagram will be created successfully. Go to File-> Properties, check the Sheet-size, it will be A3 Tall (297mm x 420mm) which was defined in CLE previously.
Keywords: drawing, type, new, template, drawing template, new template, symbol maps.
References: None |
Problem Statement: When creating a new Aspen Mtell database, whether by using the database wizard from the Aspen Mtell System Manager, or by manually running SQL scripts, the database will fail to create if mirroring is enabled on the SQL Server with the error “Failed to execute SQL command – Unable to modify or set default database for logins when mirroring is enabled as these changes cannot be applied to the mirror”. | Solution: This error occurs because SQL Server setups with mirroring do not allow individual users to be assigned a default database. This error occurs because the local “MtelligenceUser” username that is used for connecting to the MtellSuite database sets MtellSuite as the default database for the user when the script is run. To resolve this, first navigate toSolution 46473 with instructions on loading the SQL scripts manually. Open the first script in SQL Server Management Studio. Before running the script, locate the line:
exec sp_addlogin N'MtelligenceUser', N'Mt3ll1g3nc3U$3r1', @logindb, @loginlang
and replace it with the line:
exec sp_addlogin N'MtelligenceUser', N'Mt3ll1g3nc3U$3r1', NULL, @loginlang
By changing “@logindb” to “NULL”, the script no longer assigns “MtellSuite” as the default database for MtelligenceUser. Once this change is made, continue the process by executing the four scripts manually. Once this is done, the MtellSuite database should appear in SQL Server Management Studio and both Aspen Mtell System Manager and Aspen Mtell Agent Builder should be able to connect to the database with no issues.
Keywords: Mirroring
Microsoft SQL Server
References: None |
Problem Statement: This | Solution: describes how to manually create the Aspen Mtell database by running scripts from SQL Server Management Studio instead of using the database wizard provided with Aspen Mtell.Solution
The scripts run by the database wizard can be found in C:\Program Files\AspenTech\Aspen Mtell\Suite\SQL Scripts. There are four files with .sql extension in this folder. To manually create the database, open the script ending in “step1.sql” and run the script manually from SQL Server Management Studio. Once this is done, continue with the scripts ending in “step2.sql”, “step3.sql”, and “step4.sql”. It is important that the scripts be run in this exact order.
NOTE: Running the scripts manually will create the exact same database as running the scripts from the database wizard unless the scripts are modified before they are run.
Keywords: Manually run SQL Scripts
References: None |
Problem Statement: Does RYield calculate adiabatic reactor temperature rise in Aspen Plus? | Solution: Yes. RYield calculates adiabatic reactor temperature rise.
For RYield, the duty is the difference between the inlet and outlet enthalpies. You do not need to specify heats of reaction. This is because Aspen Plus uses the elemental enthalpy reference state for the definition of the component heat of formation. Therefore, heats of reaction are accounted for in the mixture enthalpy calculations for the reactants versus the products. The temperature will change if the duty and pressure drop are 0.
Keywords: RYield, Temperature rise, Aspen Plus
References: None |
Problem Statement: I need to delete some of the assays displayed in the System Custom Library. There is an option to add assay, but not for delete them. Is there any way I can delete/edit the System Custom Library? | Solution: In Aspen HYSYS there is no interface for user to delete the assays from the System Custom Library.
One workaround is that if you have PIMS installed, you can use PIMS to manipulate the UserAssayLibrar.aal file.
Another workaround is to rename the UserAssayLibrar.aal file to UserAssayLibrary.afam file. Then, open it in HYSYS, remove assays of interests, and save it as *.afam file again. Finally rename it to *.aal file.
If you want to know more about the UserAssayLibrar.aal file, you can referer to KB's: How do I share my Assay Manangement custom library data with other users? and Common methods to import an assay file into Aspen HYSYS Petroleum Assay
Keywords: aal, RefSYS, Petroleum Assay, Import Assay, Library, Customized, Custom, afam
References: None |
Problem Statement: When manually running the first script when creating a new Aspen Mtell database, SQL Server Management Studio returns the warning message:
Warning! The maximum key length for a clustered index is 900 bytes. The index 'PK_ReliabilityGroupSite' has maximum length of 1530 bytes. For some combination of large values, the insert/update operation will fail. | Solution: This message is a warning generated by SQL Server that indicates a potential size issues when adding items to the database. This message is expected and the database will be generated with no issues, so these warning messages can be ignored.
Keywords: MtellSuite
References: None |
Problem Statement: Which shortcuts or hot keys can I use in the PFD? | Solution: Manipulate PFD shortcuts:
Page Up: zoom in small amount
Page Down: zoom out small amount
Home: zoom to show entire PFD area (while a unit is selected, Home Button will center the PFD around that unit)
Z: show previous PFD area
C (or '.'): center PFD on mouse cursor
Arrow keys: move PFD area small amount
<Shift> + Arrow keys: move PFD area large amount
Adjust selected item(s):
S : select first object; select next object (in PFD's internal order of all visible objects)
<Shift> + S: select previous object
D: de-select all selected objects
Arrow keys: move item(s) small amount, if no collision occurs
<Shift> + Arrow keys: move item(s) large amount, if no collision occurs
Delete: delete associated 'engineering' object(s)
Home: zoom PFD to show selected object(s)
V or E: open view of object(s)
1, 2, 3: rotate each item clockwise 90, 180, 270 degrees
X, Y: mirror each item about its x or y axis
L: select labels; de-select objects
N: return item(s) to 'normal' orientation
Change material stream label variable:
Shift + N: toggle between stream names and last variable shown
Shift + T: Temperature
Shift + P: Pressure
Shift + M: Mass Flow
Shift + F: Molar Flow
Miscellaneous:
Hold down Ctrl: enter 'quick attach' mode from Move/Size mode
Esc: abandon 'flip streams' or 'straighten' or 'manual route' mode
Delete (while in 'manual route' mode): delete 'manual route'
F: enter 'flip streams' mode
Keywords: PFD, hot keys, shortcut keys
References: None |
Problem Statement: Does Hysys take into account liquid formation across the depressuring valve (orifice)? | Solution: No, Hysys assumes that the fluid remains as a vapour through the valve (orifice).
Keywords: Valve, Orifice, Depressuring.
References: None |
Problem Statement: The concept of sub-units was used in V9 to model groups of components, within a Unit, using a sub unit. The sub-unit would contain more than one component and then would be in embedded in the Unit. In V10 there is no longer sub units or embedding. How do you then create the same component sub unit groups concept in V10? | Solution: ThisSolution demonstrates and example of creating a sub-unit using the Free Layer option in V9 (MS Visio) and then embedding this Free Unit within a Unit object. This work-flow is then contrasted with the current unit diagram interface in V10 and the changes in Unit elements (Events) interactions that no longer requires the use of sub-unit modules.
Sub-units in V9
The example below is that of two Pumps in Parallel, P-300A and P-300B with an operation philosophy of 2 by 100%. Each Pump has a failure distribution which is compounded by the pump motor failure rate as well. The pumps’ motor must be configured to reflect the impact of both the Pump and Motor failure on the model.
In V9 of the program a free unit layer is used to create a sub-unit.
Inside the free layer unit, add objects to model equipment as required. As per our example, the pump and motor, for each leg of the train, are added and connected in series.
One sub unit is configured for each Pump in the train
Inside the Unit level, the sub-unit consisting of a Pump and Motor, is added using the Module -Unit classic object. Each leg in the train is configured as a single ‘component’ and the operational philosophy is defined for each sub-unit selected within the classic unit module
As mentioned earlier, Pumps P-300A and P-300 B are defined with an operational philosophy of 2 by 100%:
Unit Elements (Events) Interaction in V10
In V10, each Pump and Motor will be connected as events in series, directly within the Unit object, and a Rate Multiplier (RM) will be configured upstream of the Pump parallel train to define the operation. There is no longer a need for a sub-unit layer. In V10, the links within a Unit can be used to influence flow rate and direction. This was not the case in V9, where the links within a Unit had no significance.
Next, define the RM node to reflect the operational philosophy of the pump parallel train, 2 by 100%. The Response Configuration feature in the RM node allows the user the select the number of events in the train that need to be up to provide 100% operation. The capacity multiplier for each path in the parallel train will equal to:
1/Response Configuration selection.
Note that an RM node is not required between each pump and motor connection, this is because they are connected in series and for the path of that train to be up, both must be up.
Keywords: Sub-units in Aspen Fidelis Reliability V10, Module units in AFR V10, Embedding in AFR, response configuration, parallel trains
References: None |
Problem Statement: In this sample, you will learn how to use the Production Allocation Utility for systems with multiple suppliers for inlet feeds and track the individual supplier contributions to the resulting products. You will also understand the basis behind its calculations within a given sample case. | Solution: You will learn to:
Add the Production Allocation Utility
Review the feed stream contribution for the products
Understand the calculations performed by the Production Allocation Utility
The Aspen HYSYS case used as reference in the guide is also attached.
Note: The Aspen HYSYS Upstream license is required to run the Production Allocation Utility.
Keywords: Production Allocation Utility, HYSYS Upstream, Tutorial, Sample, Model Analysis.
References: None |
Problem Statement: Microsoft frequently releases individual hotfixes for the Windows operating systems to fix defects and to patch security loopholes. End users often inquire whether or not these individual Microsoft hotfixes are compatible with the Engineering products. This knowledge base article describes AspenTech's policy towards application of Microsoft hotfixes on server and client computers which use the Engineering products. | Solution: AspenTech tests new versions of the Engineering products with the latest Microsoft service packs and Microsoft hotfixes which are publicly available from Microsoft when the testing cycle begins for a new release. After product testing is completed and the new Engineering version is officially released, no additional testing is retroactively performed with subsequently released Microsoft hotfixes.
The AspenTech development team will address incompatibility issues which are caused by Microsoft hotfixes and the Engineering products. If any incompatibilities are verified between a Microsoft hotfix and an Engineering product, AspenTech will publish a knowledge base article to alert the user community.
Note: If any problems are encountered with a particular Microsoft hotfix, the hotfix can always be uninstalled by following this procedure:
1. Stop the AspenTech applications which are running.
2. In Control Panel | Add or Remove Programs, select the newly applied Microsoft hotfix then click on the Remove button.
3. Restart the AspenTech applications.
Keywords: patch
fix
MS
update
hot-fix
References: None |
Problem Statement: The Aspen Security components store security/role information in cache files on the local client computer in case contact with the Aspen Security server is lost. These cache files are written to the computer using the client user's login credentials. However, some IT departments have restrictions which limit the location where users can write data on a drive. This knowledge base article describes how to change the default location for the Aspen Security cache files. | Solution: The path to the Aspen Security cache files can be changed using the AFW Tools application.
To start AFW Tools go to:
Start | Programs | AspenTech | AFW Tools
AFW Tools displays Aspen Security setting information stored in the Windows registry. The path where the Aspen Security cache files are stored is displayed in the entry for CachePath. This information can be edited by double clicking on CachePath then changing the path.
After the path has been changed the AFW Security Client Service must be restarted for the change to be recognized.
Typically, the above path contains four files -
aclcache.xml
AfwCache.txt
ApplCache.xml
rolecache.xml
In case AFW security server is migrated from one machine to another machine, the above procedure will be applicable
in case cache file path changes in new server.
Keywords: Cache file
AFW tools
AFW local security
Change path
References: None |
Problem Statement: Why are the units in my report different than those displayed in HYSYS? | Solution: In Aspen HYSYS V10, Reports tool can be accessed under Home Tab > Summaries Section. Reports Manager is the main interface to create report, as seen on the screenshot:
On the right side, under Printing Section, user can customize format options including units by clicking Format/Layout. Report Format and Layout window will pop up, user adjust Unit Set within here. To match the report unit set with the current Flowsheet unit set, select <Current>
Keywords: units; print
References: None |
Problem Statement: Why does HYSYS display a standard gas flow for a liquid stream? | Solution: The reason that HYSYS displays a value of Standard Gas Flow for both liquid and gaseous streams is that the calculation is based on the molar volume of an IDEAL GAS at standard conditions (1 kgmol occupies approximately 23.644 m^3). So the molar volume is a direct conversion of the stream's molar flow rate. This calculation is dependent only on total molar flow rate and independent of the stream composition.
For example, if you had a stream with a vapor fraction of 0.5 flowing at a rate of 100kmol/h, the overall standard gas flow would be 2364.4 std_m3/h and the flow of each stream would be 1182.2 std_m3/h.
Keywords: standard gas flow, liquid stream
References: None |
Problem Statement: What are the basic steps of Open loop tuning of PIDIncr? | Solution: The open loop tuning approach assumes that the process can be approximated by a first order lag plus dead time. Please follow these steps to execute open loop tuning for PID controller:
Open the PIDIncr controller Faceplate and set the controller to “Manual” mode
Open the “Tune” tab and select “Open Loop” radio button. Select the test step direction as up or down and the size of the step as a percentage of output range. You can try different steps directions and sizes to investigate how these affect the output. Usually more non-linear the process the greater the differences are.
Click the “Start Test” button and review the response plot. The response of the PV is used to estimate an open loop gain, time constant and dead time for the process.
Key Words
PIDIncr, Tuning, Open Loop, Step, Manual
Keywords: None
References: None |
Problem Statement: How to predict better viscosity for heavy oils? | Solution: Besides using Tabular properties, an alternative is to use the MacroCut Table available through HYSYS Petroleum Refining Features.
If you have a stream a crude stream and know the gas oil ratio, the water oil ratio, the stock tank density and the gas composition, HYSYS can calculate an oil composition and you can define bulk properties to tune a given viscosity.
For example, to do this, you need to go to the material stream and select Worksheet | Oil & Gas Feed and choose the option Oil & Gas Feed with Oil Assay Info
Next, you need to input the GOR, WOR, Stock Tank density and Gas composition. Please know that if you do not have this information, this might not work. Also you can characterize your crude from here if you have a distillation curve. Just click under View Details to open the MacroCut Table.
Select the number of points to add at the bottom left and click on Add. This will allow you to add the distillation data points.
Fill in the data and define the temperature ranges.
After that, go to the Settings tab and define temperatures for viscosity at which you want to tune the viscosity.
Then go back to the Specifications tab and add the viscosity at the desired temperature to the property list.
Introduce the viscosity value as bulk property and see the effect on your stream. If the viscosity is still not good, change the value to tune and achieve the desired one.
Keywords: MacroCut, Viscosity, Heavy Oil
References: None |
Problem Statement: If you did not define the feed and product stream variables correctly, sometimes you will get the following errors when trying to run adsorption models: “Initialization failed at time 0”, “Singular decomposition”. | Solution: The way you defined the variables is probably not very robust. In Aspen Adsorption, it is not recommended to set the product flow rate as fixed or initial. It is also not recommended to specify the feed flow rate and pressure while leaving the product pressure free. The specification status may give a warning, and the simulation can be prone to failure.
The most robust way is to set the feed and product pressures to be fixed. A second choice is to set feed flow rate and product pressure. The second choice may cause pressure spikes when not enough material is available to meet the specified flow.
Keywords: Fixed variable
Free variable
Robustness
References: None |
Problem Statement: How does the ‘Simultaneous | Solution: ’ solving method of the ‘Adjust’ logical operation work?Solution
The Adjust operation in Aspen HYSYS can solve multiple loops simultaneously by using the ‘SimultaneousSolution’ method. This solving method can be used when a set of manipulated variables in a specific object are to be varied simultaneously to meet the specified values for multiple target variables.
The objective of the attached example simulation file is to illustrate the use of the ‘SimultaneousSolution’ solving method, so that users can extrapolate it to their models. A tee operation equally splits the flow of its feed stream to three different pipe segments. Each pipe segment has unique length and fittings that result in different computed pressure drops, so the pressure at each pipe outlet stream is different from the others.
Two Adjust operations are used to manipulate the tee flow ratios to match the pressure of streams ‘2-B’ and ‘4-B’ with that of stream ‘3-B’. Since the tee operation is set up with ‘n-1’ flow ratios, where ‘n’ is the number of inlet streams, two flow ratios need to be manipulated simultaneously by Aspen HYSYS to find aSolution. In this example, the tee flow ratios for streams ‘2A’ and ‘3A’ are set as the adjusted variables. The adjust operations are set to ‘SimultaneousSolution’ mode and the model solves. Streams ‘2-B’, ‘3-B’ and ‘4-B’ reach the same pressure, 751 psia; and the calculated flow ratios are 0.3924 for ‘2-A’, 0.2957 for ‘3-A’ and 0.3119 for ‘4-A’.
Keywords: Adjust, Simultaneous
References: None |
Problem Statement: Is it possible to use SimSci Flare files in Aspen Flare System Analyzer? | Solution: Aspen Flare System Analyzer cannot read SimSci file and does not have a converter tool.
Please contact Schneider support team and verify if the SimSci file can be saved in a different format that Aspen Flare System Analyzer can read.
Keywords: SimSci, Converter
References: None |
Problem Statement: How can I control the Total Operating Cost obtained in Activated Economics in Aspen HYSYS or Aspen Plus? | Solution: The Total Operating Cost is the same value that Aspen Process Economic Analyzer (APEA) reports as Operating Labor Cost. For more information on what this value means and how it is calculated, please review article 46522.
While running the estimation inside Aspen HYSYS or Aspen Plus, the only parameter that can be controlled for this calculation is the Operating time, identified as the number 8000 in APEA default calculation shown in article 46522.
This number can be controlled under Economics | Cost Options, by changing the Operational Year hours.
If you wish to change the Unit Labor Costs (OWR or SWR), then you need to generate a Template File in APEA and enter the information on the Project Basis View under Operating Unit Costs. Once the template has been generated, you may use it inside Aspen HYSYS/Aspen Plus by loading it inside Economics | Cost Options.
For more information on templates please review article 40571.
Keywords: Labor Cost, Modify, Activated, Summary, Supervisor, Operator.
References: None |
Problem Statement: Do the HYSYS Pipe Segment and PIPESYS predict the temperature profile close to the wall? | Solution: The Pipe Segment and PIPESYS predict the bulk temperature profile, not the temperature profile across the pipe diameter.
To calculate the temperature close to the pipe wall, you would need a 2D or 3D finite element program and presently AspenTech does not develop such products.
Keywords: Pipe segment, PIPESYS, Temperature Profile, Close to Wall
References: None |
Problem Statement: Fittings equivalent length is not being considered for the calculation of total equivalent length, but only pipe straight length. Why? | Solution: After running a model, users may check the calculated total equivalent length of a pipe on the ‘Summary’ tab of the pipe block.
However, total equivalent length will be the same as pipe straight length (ignoring fittings equivalent length) every time the upstream source mass flow is zero. For sources with non-zero mass flows, total equivalent length will also consider fittings equivalent length.
The images below illustrate a case in which a tailpipe, 25m long, has two elbows as fittings. The mass flow of the source upstream is 100,000 kg/hr. When the model is run, the calculated total equivalent length is 35.51m.
On the other hand, when the mass flow for the same source is set to zero, total equivalent length is the same as pipe straight length, in this case 25m.
To know more about fittings equivalent length, consult the following articles:
130184 - 'How are equivalent length of fittings calculated in Aspen Flare System Analyzer?'
125750 - 'Fitting Loss Coefficients in Aspen Flare System Analyzer'
Keywords: Equivalent Length, Fittings, Pipe, Mass Flow.
References: None |
Problem Statement: How can I control all the significant digits for Pressure that appear on the Aspen Flare System Analyzer PFD? | Solution: When the user displays the Pressure results on the PFD, only two kinds of objects will display these values, Sources (valves) and Pipes, showing the pressure upsteam and downstream of each object.
To control the number of significant digits that are shown for any value in Aspen Flare System Analyzer, the user can go to File | Preferences… | Formatting and click on the Edit Variable Formats button.
Once in the Variable Formats Editor, the user should locate the following variables:
Value in PFD Route in Variable editor
Source Upstream Pressure SourceData | Static Pressure (Top of the list)
Source Downstream Pressure SourceData | Static Pressure (Below Kb)
Pipe Pressure (Upstream & Downstream) Results | Pressure property
By double clicking any of these variables, the user will see the option to select how many significant digits shall be displayed, configure these three fields to accommodate the shown digits in the PFD.
Make sure to Click OK in the Format editor and on the Preferences window again to apply the changes.
Keywords: Digits, Significant, PFD, Pressure, Format, SourceData, Results
References: None |
Problem Statement: Why does No FlowPath Data For Source appears under Profile results in Aspen Flare System Analyzer? | Solution: Under the Profile results form of Aspen Flare System Analyzer (AFSA), the user can select any Source (Valve) to display a property profile that shows all the changes from the selected source and all the way up to the flare tip.
The profile is generated by identifying a single sequence of objects that connects the selected source to the tip.
AFSA will generate and show how a property changes from one node to another:
However, if at some point of this sequence the program finds a node with two different outlets connected to it, the program will stop being able to identify the single sequence to report the property profile, hence the message will appear.
Keep in mind when using this profile, that generating this profile may not be possible in looped or divergent flare systems most usually.
Keywords: FlowPath, Profile, Sequence, Error, Results
References: None |
Problem Statement: Why are the units in my spreadsheet different from those in the rest of my case? | Solution: The spreadsheet has a feature where you can run a different unit set from your simulation - this could be useful when you are doing extra calculations that require a specific unit (i.e., emission calculations). If the units in your spreadsheet don't match those in your case, you can change the Units Set on the Parameters tab of the Spreadsheet operation. Assign the same unit set as the one assigned to the rest of your case.
Keywords: spreadsheet, units
References: None |
Problem Statement: I have two streams with the same petroleum assay attached, but in one stream (Gasoline1) the user property (Sulfur Trial) appears empty and in the other stream (Gasoline2) is filled. Why is this happening? | Solution: In Aspen HYSYS, you can specify the Min. Def. Comp. field that is the minimum total composition that must have non-<empty> values for this user property in order for the stream value to be calculated. In other words, the summation of the NBP must be greater than the Min. Def. Comp. value (75% by default).
If the total composition with non-<empty> values for this property is smaller than the Min. Def. Comp., the stream value will be <empty>.
In Gasoline 1 the summatory is 55 % and in Gasoline2 the summatory is 75 %. If the customer want to see the user property in both stream, it must be necessary to change the value of the Min. Def. Comp. to 55 %.
Keywords: User Property, Min. Def. Comp., Value, Petroleum Assay, NBP.
References: None |
Problem Statement: By default, Aspen Mtell creates new databases in Microsoft SQL Server under the name “MtellSuite”. This | Solution: discusses how to create the database and associated .mdf and .ldf files under a different name.Solution
First, followSolution 46473 with instructions on loading the SQL scripts manually. Before running each of the scripts, change all occurrences of “MtellSuite” in the script to be the new desired name for your Aspen Mtell database. This occurs seven times in the first script (all within the first 25 lines of the database) and only once in each of the other three scripts (all on the first line of the database).
Keywords: MtellSuite
References: None |
Problem Statement: How to select Explosion Proof motor for pump in ACCE? | Solution: The Electrical Class Division set in either the Project or Area level in ACCE (this is not exposed in APEA) will determine whether explosion proof motor will be selected for pump motor.
In ACCE it can be set at the project level via the following:
Here are the defaults by Country Basis:
As an example, in the US basis, the default is Class I Div 2. So if you evaluate a pump with this default, you will get a standard TEFC or TEWAC motor based on the power threshold described in KB # 45918.
However, if you change the Electrical Classification type to Class I Div 1 (which is highly flammable) either at the project or area level, the system will automatically provide an XP motor (explosion proof) – notice the increase in motor cost:
The different electrical classifications are in Ch 22 of the Icarus
Keywords: Explosion proof driver, pump motor
References: Guide. |
Problem Statement: What triggers Message 18068 Dependent (variable name) response is suspicious, possibly a bad model? | Solution: The reason that causes Message 18068 to pop up is that the engine is detecting a wrong sign gain for that response curve.
Please note that this does not have an effect on the SmartStep MV moves but the data will be removed during the auto slicing process in Adaptive Modelling.
Keywords: Message 18068
References: None |
Problem Statement: What can I do to avoid having my original and copied reaction sets to change all the same when I make a modification on any of them? | Solution: The root problem of this odd behavior is that when reaction sets are copied in Aspen HYSYS, the name of the sets will be different and unique for each (i.e. Set-1, Set-2, etc.), but the reaction set folder is given the same name for all sets.
Therefore, for Aspen HYSYS, there is only one reaction set object, regardless of the sets the user may had created. To overcome this situation, the user may export - import the master (original) reaction set.
Follow the next steps:
1) Go to the main ‘Reactions’ folder, left-click on the original reaction set and then click on the ‘Export Set’ button. Save the generated *.rst file (reaction set file) under a suitable location.
2) Next, click on the ‘Import Set’ button and browse to the location of the recently created *.rst file and import it.
3) Notice that this time, both the new set and reaction set forms are named different from the original forms, which will make it possible to make changes independently among sets.
Keywords: Reaction Set, Export Set, Import Set.
References: None |
Problem Statement: How do I organize the variables in the Aspen Simulation Workbook (ASW) Organizer? | Solution: It is possible to have a large number of model variables mapped into ASW Organizer and the variables may be from a single flowsheet or from different subflowsheets in an Aspen HYSYS case, and may be from global or any hierarchal level in a case of Aspen Plus. It is useful to group the variables according to the variable name or flowsheet name and then display them in groups. The following procedure will outline how to group variables and to display the group names for simplification purpose.
If you are trying to group the streams from different sources based on the variable type, you can achieve this with the following steps, and the groups can be dropped into Excel as tables using the Table template.
Map all different variables into the organizer, and then click on the Column Customization button.
From the Customization window, select Group and drop it on the column headings. When finish, close the Customization window.
Then right mouse click on the Variable Name heading and select the option Group By This Column.
The variables in Organizer will be grouped and listed according to the variable type.
After grouping, you can paste them in Excel spreadsheet with the pre-built table template.
Keywords: ASW, Organizer, Group Variables, Quick Table
References: None |
Problem Statement: When will Aspen Flare System Analyzer consider the flow as compressible flow and what is the difference in the | Solution: method from incompressible flow?Solution
Compressible flow happens when the density of the fluid changes in the flow field (any flow with a Mach Number greater than 0.3 is considered compressible). The fluid mechanics of compressible flow is different from incompressible flow in the fact that the energy and momentum equations are strongly coupled thru the fluid property law (i.e. VLE Method / Ideal Gas Law, etc.).
As the user may already know, when rated flow is checked in the solver options form, Aspen Flare System Analyzer uses required flow (mass (design) flow) as the flow basis for the energy balance equation, but rated flow as the flow basis for the momentum balance (i.e. pressure drop equation). Hence, with compressible flow, if widely inconsistent flow bases (rated flow and mass (design) flow) are used in the pressure and energy equations, there can be inaccuracies in theSolution. These inaccuracies can be negligible if the difference between rated flow and mass (design) flow is small (i.e. just a few % points).
Keywords: Compressible Flow, Incompressible Flow, Mach Number, Energy Balance, Pressure Drop.
References: None |
Problem Statement: There are three Acid Gas Property Packages available in HYSYS. What is the difference between them? | Solution: HYSYS offers the following property packages for use with Acid Gas Cleaning:
The Acid Gas Chemical Solvents Property Package is used by the HYSYS acid gas cleaning workflow to simulate removal of acid gases such as Hydrogen Sulfide, Sulfur Dioxide, Mercaptans, and Carbon Dioxide from process streams. The workflow includes acid-gas specific inputs and performance outputs within the stream and column models, a rigorous rate-based calculation model that performs calculations within the HYSYS column, and a makeup unit operation that ‘makes up’ for the loss of amines and water in the system.
During Fluid Package setup, HYSYS automatically selects the Acid Gas Chemical Solvents property package if the components list contains one of the following amines: DGA, DIPA, MDEA, MEA, PZ, Sulfolane-DIPA, Sulfolane-MDEA, TEA, DEA, and any combinations of the amines. See the complete list of supported amine blends below.
The user must add the following components to the case in order to add the Acid Gas Chemical Solvents property package:
At least one supported amine or amine blend
CO2
H2S
H2O
The Acid Gas Chemical Solvents property package supports the following amines and amine blends.
DEA
DGA
DIPA
MDEA
MEA
PZ
TEA
The Acid Gas Liquid Treating property package is available to model acid gas removal from LPG (Liquefied Petroleum Gas) and NGL (Natural Gas Liquids).
Since the main hydrocarbon components are ethane and propane and the typical process operates at low temperatures and high pressures, a special thermodynamic package is required to properly model the liquid-liquid equilibria involved.
The same thermodynamic framework used for the Acid Gas Chemical Solvents package is used here, but with binary and electrolyte pair parameters optimized for liquid-liquid applications. In addition to modeling the liquid-liquid extractor, the package can also be used to model the regenerator. The package should not be used to model a traditional Gas-Liquid Absorber.
The user must add the following components to the case in order to add the Acid Gas Liquid Treating property package:
At least one supported amine or amine blend
CO2
H2S
H2O
The Acid Gas Liquid Treating property package supports the following amines and amine blends:
MEA
DEA
MDEA
DGA
MDEA + PZ
It also supports the main LPG and NGL components (ethane and propane), other light and heavy hydrocarbons (up to C7), BTX, COS, CS2, and light mercaptans (methyl mercaptan and ethyl mercaptan). Heavy hydrocarbons (C7+) and heavy mercaptans supported by the Acid Gas Chemical Solvents package are not supported.
The Acid Gas Physical Solvents property package is used to model acid gas removal using DEPG. This property package is based on the PC-SAFT equation of state and contains PC-SAFT model parameters and other transport property model parameters that were obtained from regression of extensive thermodynamic and physical property data for DEPG and related components.
It is a proven model that can represent a wide range of compounds, including hydrocarbons (up to C7), inorganic gases present in natural gas streams, light mercaptans (methyl mercaptan and ethyl mercaptan), water, and other polar and associating components. The model can fit vapor pressure, liquid density, and liquid heat capacity very well without requiring volume translation terms. Often, both VLE and LLE can be represented with the same binary interaction parameters. Furthermore, the model supports modeling of petroleum fractions (hypothetical components). Heavy hydrocarbons (C7+) and heavy mercaptans supported by the Acid Gas - Chemical Solvents package are currently not supported.
Unlike the Acid Gas Chemical Solvents package, only the Equilibrium column model is supported. The Efficiency model and the rate-based Advanced Modeling model are not available. The physical solvent DEPG has very strong interactions with CO2 and H2S. Therefore, it is reasonable to assume that equilibrium is reached in the column. In addition, component efficiencies can be used to effectively tune the model to match plant data.
The user must add the following components to your case in order to use the Acid Gas Physical Solvents property package:
DEPG
CO2
H2S
H2O
The restrictions of this fluid package are:
Solids and Amines are not supported.
Assays cannot be added to the component list.
Cannot be used in EO cases.
Cannot be linked to any reaction sets.
Keywords: Acid Gas, Fluid Package, Property Packages Acid Gas Cleaning, Acid Gas Chemical Solvents, Acid Gas Liquid Treating, Acid Gas Physical Solvents, Amine Blends.
References: None |
Problem Statement: What is a Series-based Sensitivity Analysis and how do I set it up? | Solution: Unlike a standard Sensitivity Analysis, a Series-based study varies only one manipulated (independent) variable at a time and holds the other variable(s) at their respective base case values. This results in a significantly smaller output table. For instance, assume we select three independent variables, each with five distinct values. In a normal Sensitivity Analysis, this would result in a table with 125 results (5x5x5) because all combination of the variables would be evaluated. However, in a Series-based study the output table would contain only 15 results (5x3) because only one independent variable is adjusted at a time and the other two are held at their original values.
To set up a Series-based Sensitivity Analysis, please see the attached file along with the steps below:
First, create a standard Sensitivity Study following the normal steps. Please see KB Article # 46056 for more information:
https://esupport.aspentech.com/S_Article?id=000046056
After the Sensitivity Analysis setup is complete, click the Options tab and check the box next to Series.
Next, run the simulation. The solver will now process the cases by adjusting the independent variable(s) and recording the results of the dependent variable(s). To view the output after the run has completed, click on the Results form under the Sensitivity Analysis from the Navigation Pane.
Note that only one variable was manipulated at a time. The other two variables were held constant at their base-case values (the original input values from the main flowsheet).
Keywords: Series, Sensitivity Analysis
References: None |
Problem Statement: Can I use the HYSYS Optimizer in a Sub-Flowsheet? | Solution: The original Hysys Steady State Optimizer can only be used in the main flowsheet environment of a simulation case.
The HYSYS SQP optimizer uses a set of variables which are collected in a Derivative Utility. Variables from subflowsheets can be included in the Derivative Utility for use in this optimizer.
Keywords: Optimizer, Subflowsheet
References: None |
Problem Statement: What methods are available to calculate polytropic head for a centrifugal compressor? | Solution: Head Calculation Methods
In Aspen HYSYS version V7.0, two new approaches are introduced for the polytropic head calculation: the Huntington and
Keywords: Schultz, Huntington,
References: methods. Both are described in detail in R.A. Huntington, Journal of Engineering for Turbines and Power, 1985. Both methods are applicable when performance curves are defined and when they are not used.
Schultz
This is the method currently used by Aspen HYSYS to calculate the polytropic head and efficiency in centrifugal compressors. This method is based on a simple polytropic path from inlet to discharge conditions. Schultz method (Schultz, J.M., ASME Journal of Engineering For Power, Jan. 1962, pp 69-82) is based on the assumption that the gas compression follows a simple polytropic path as shown below:
(1)
Where n is calculated based on the conditions at the beginning and end of the polytropic path. This equation is combined with the definition of polytropic head
(2)
That upon integration between > gives
(3)
Or
(4)
The polytropic efficiency can then be calculated from
(5)
Notice that a real compression is not reversible and it must be path-dependent instead of endpoint dependent. To compensate for this effect Shultz introduced a correction factor usually called the polytropic head (Schultz, J.M., ASME Journal of Engineering For Power, Jan. 1962, pp 69-82).
(6)
Where f the polytropic head factor is defined as
(7)
That for an isentropic compression/expansion gives and e = 1.
The Schultz method has long been recognized as required by the ASME Power Test Code 10 and it is well accepted by industry.
Huntington Method
This method tries to use the definition of the polytropic path (constant value of e in Equation along the polytropic path). Combining equations and with the Maxwell equation yields the general relationship of the entropy derivative along the polytropic path:
(1)
In this method, a general relationship of the compressibility factor and pressure is assumed along the polytropic path of compression for a simple analytical integration. It is important to point out that Huntington tried several functional relationships Z(P) in his work and checked them against the results obtained in the reference method. The following relationship showed the most accurate results:
(2)
where the constants a, b, and c are evaluated from the compressibility factor found at the endpoints of the compression path and at one intermediate pressure along the path as follows:
(3)
And the first estimated intermediate temperature, is assumed below:
(4)
The initial defined above may be improved by using recursive calculations as described in Huntington's paper. With the Z(P) given by equation (2) Huntington integrates equation (1). After rearranging some terms the following equation is obtained for the polytropic efficiency:
(5)
Reference Method
The definition of polytropic path (R.A. Huntington, Journal of Engineering for Turbines and Power, 1985) is for a real gas the path where the ratio of reversible work input to the enthalpy increase along the path is constant
(1)
(2)
where e is a constant along the path. This equation can be integrated numerically dividing the pressure range in sufficiently small intervals such as V can be assumed to be constant in this interval. An iterative procedure can be implemented where temperature and pressure are known at the beginning of the interval but only pressure is known at the end. Then we iterate on the temperature until equation (2) is satisfied. Also an alternative procedure can be used where equation is used in each integration interval instead of assuming a constant volume.
It is important to point out that this method does not make any assumption regarding the pressure-volume relationship along the path can be used as a reference to check the accuracy of the other methods, e.g. the Schultz method and the new method suggested by Huntington in the paper. Although perhaps not the intention of Huntington in his paper, the reference/integration method can be directly implemented. And they are indeed implemented in Aspen Plus: piece-wise integration and n-method piece wise integration, the latter being the approach where equation substitutes the assumption of constant volume in the integration interval.
This method is based on the numerical integration of the equations that define a polytropic path
H = Vdp and H = edh , without any assumption regarding the form of the polytropic path or the compressibility factor dependency on pressure. The integration method requires the polytropic
efficiency to be constant so it can be used only when the user specifies a value for the polytropic efficiency or when the performance curves have been defined for polytropic efficiency. |
Problem Statement: How to correct failed initialization for undersized choked valve? | Solution: In Aspen Plus valve design mode, although choked condition is detected but is ignored during valve sizing calculations. So, the sized valve has under-estimated valve open position (%). However, Aspen Plus Dynamics valve model accounts for choking effect. If the Aspen Plus simulation is exported in Pressure Driven mode into Aspen Plus Dynamics, the flow in dynamics will not match that in the steady state simulation and the simulation may fail to initialize.
To correct this, we need to invoke the “Resize” script for the concerned valves and run in “Initialization” mode first.
Key Words
Valve, Choked Flow, Failed Initialization, Sizing, Resize
Keywords: None
References: None |
Problem Statement: What is the Mach Number Unit Operation Extension? | Solution: This extension calculates Mach numbers for a given pipe or stream. It has three modes:
Profile - Calculates a Mach number profile through a selected pipe. This is based on the mean velocity and local speed of sound at each point in the pipe.
Stream - Calculates a Mach number for a selected stream and a specified pipe diameter. The pipe diameter can either be input by the user or can be obtained from a pipe connected to the stream (downstream if one exists, otherwise upstream).
Classic - Calculates a Mach number for a selected pipe or for all pipes on the flowsheet. In this mode, volumetric flow and speed of sound are calculated based on feed conditions and are assumed not to change within the pipe.
Key Words
Mach number, extension
Keywords: None
References: None |
Problem Statement: What is the preferred property mode for polymer system? | Solution: By default, for polymer system calculations, Aspen Plus Dynamics uses Rigorous properties calculation. Although “Local” is the default setting as global property modes, all polymer properties calculations are still done in rigorous mode.
Key Words
Polymer, Properties, Rigorous
Keywords: None
References: None |
Problem Statement: How to implement kinetic mechanism in Aspen Custom Modeler? | Solution: This example is based on ethane thermal cracking described in Folger Elements of Chemical Reaction Engineering. The details can be found in that book. The principle of the method is the Pseudo Steady State Hypothesis (PSSH), which may also be known as Quasi Steady State Approach (QSSA). The idea is that the radicals will reach quickly a stationary concentration, which can be found by assuming that the sum of generation and consumption for each species is zero. With a bit of algebra, one can then derive the compact kinetic expression.
Implementation of a kinetic mechanism with radicals using this approach in Aspen Custom Modeler is demonstrated here.
Firstly, you can take a look to the simulation file example-batch.acmf, which compares the full set of ODE and the set of ODE where the radicals have been eliminated by using the compact kinetic expression. See the plot plot_difference which shows the difference between the composition calculated using the full ODE with radicals, and the composition with the PSSH approach. This demonstrates that the PSSH method is valid (as long as the residence time is long enough).
The objective is to have the reaction rates calculated from the mechanism, without having to do the algebra. In other words, we want to let the solver eliminate the radicals using the PSSH method. See the file ethane10.acmf. The model test can be used in steady state (it is a CSTR). It can also be exported to be used in Aspen plus. The model batch_reactor_2 is the same batch reactor as in the example-batch.acmf, but now we use the kinetic reaction rate submodel RateCalc which implements the PSSH in a generic way. The user could modify the structure MechanismData, and possibly declare it as external in the reactor and kinetic submodel for generalization.
The benefits are:
- no need to work out tedious algebra to derive compact kinetic expressions
- allows quick modification of reaction mechanism
- reasonable convergence properties
Keywords: PSSH, QSSA, kinetic, submodel
References: None |
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