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Problem Statement: How to save MBO model | Solution: s by matrix row and column to databaseSolution
To list MBO optimization results in database by matrix row and column, please select “SaveSolution to Database” in Multi-Period Blend Optimization dialog box. After optimization, MBO will outputSolution values in Table LPSOL in database, with row/column names, MIN/MAX limits, activities etc. information included.
Keywords: None
References: None |
Problem Statement: Model keeps running when it is supposed to stop. How do I troubleshoot? | Solution: The end of cycle may be defined by a criteria that is never met. In the Cycle Organizer under Step | Control, the end of a step is specified as either time or event driven. If the end of the step is event driven, ensure that the event actually occurs. Create a plot of the variable of interest to check if it reaches the desired value. Also consider using time driven steps where possible.
Keywords: Adsorption, cycle, stop criteria
References: None |
Problem Statement: How to convert an APS/MBO database from ACCESS to SQL Server? | Solution: There are two major steps required:
1. Create an APS/MBO SQL database structure using the script provided by AspenTech.
2. Use the DBCopy utility provided by AspenTech to copy the database from ACCESS to SQL server.
Create an APS/MBO SQL database structure
1. Create a new APS (or MBO) SQL Database, for example, called APS_DB, as shown below.
2. In Microsoft SQL server Management Studio, from File | Open the script from APS folder, 'SQLServer_Create_Tables.sql'
3. Make sure to point to the new database 'APS_DB', then click 'Execute'.
Now the APS database structure is created. Create a DSN file from Control panel | Administrative Tools | Data Sources (ODBC).
Use DBCopy (OrionDBCopy32 here) to copy the database from ACCESS to SQL server
Download the attached ORIONDBCopy32.exe to your APS direcoty. If you are running Windows 7, please run it as administrator.
1. Run ORIONDBCopy32.exe
2. Fill in the fields below as desired
3. Click 'Run'
The Source database data now will be copied to the SQL server database.
Keywords: Migrate
Migration
convert
ACCESS
SQL server
database
References: None |
Problem Statement: What does the perforation percentage field in the LNG exchanger in Aspen HYSYS represent? | Solution: The perforation percentage is the percentage of perforation with respect to the total fin area. Hence, it cannot be 100%. In Aspen Exchanger Design and Rating, it is called porosity.
For perforated fins, Aspen Exchanger Design and Rating gives a rule of thumb value of 5%. This only applies to perforated fins. Serrated fins will have zero as perforation percentage.
Keywords: Perforation, LNG exchanger
References: None |
Problem Statement: This article explains what is 'Engineer Request' entry in PCWS control page. | Solution: Each variable in an Aspen APC controller has the concept of 'In Service' or 'Out of Service', it allows the variable to be turned OFF for the controller, but not at the DCS level.
'Engineer Request'is the service switch for an variable. It permits engineers to assign any of the following modes that determine whether the variable is included or excluded from the controller's influence on the plant.
It contains 3 options for Independent Variable:
0 (Off) Not included in controller calculations
1 (On) Included in controller calculations
2 (Prediction) Included in controller calculations for prediction only (Manipulated inputs only)
It contains at 2 options for Dependent Variable:
Controlled Variables:
0 (Off) Not included in controller calculations
1 (On) Included in controller calculations
If the service request of a variable is set to OFF, the variable is bad.
Keywords: Engineer Request
PCWS
entry
References: None |
Problem Statement: How do I open a CAP_REP.CCP file if I do not have ACCE running? | Solution: You can open a ccp report either with Notepad or with the Economic Evaluation Report Editor.
The Economic Evaluation Report Editor application is launched through ICEdit32.exe, located in this directory:
C:\Program Files (x86)\AspenTech\Economic Evaluation <version>\Program\Sys.
Keywords: ccp report, Economic Evaluation Report Editor
References: None |
Problem Statement: Why do I see a very poor separation performance than I expect when I model a real separator, even though all the carry-over specifications and/or correlations have been set correctly and the separator has solved? | Solution: Users may want to check the product nozzle locations and diameter.
If a product nozzle with certain diameter is located so that the interface of two phases is being covered by the nozzle, then there will always be two phases of the flow going through this nozzle, no matter which product phase this nozzle was meant to design for. In other words, more than one phase will go through the same nozzle, not because of the carry-over effects but because of the nature of the nozzle location and phase distinction inside the vessel.
Users would need to adjust the elevation of the nozzle location(s) or its diameter or both, in order to make one phase occupy this nozzle's entire cross-section of the exit space.
Keywords: poor separation performance, real separator, nozzle location elevation, nozzle diameter, two phase, three phase
References: None |
Problem Statement: How to avoid “non-square” flowsheet scenario for dual-fuel boiler optimization case? | Solution: Dual fuel boiler model has access to two different fuel sources simultaneously. Between two fuels, one fuel flow should be fixed while other should remain free. In order to have flowsheet updated correctly after optimization run, parameter “BalanceFuel” must be selected to the fuel source that is selected as free. Otherwise flowsheet update will make the flowsheet a “non-square” problem and hence fails to run.
From the Summary table, please select either Fuel 1 or Fuel 2, whichever is set as free variable.
Key Words
Dual Fuel, Optimization, Fixed, Free
Keywords: None
References: None |
Problem Statement: What are the units for isotherm parameters? In the chromatography column specification table, the parameters seem to be unitless. | Solution: In the chromatography column specification table, you may see the unit of isotherm parameters is n/a.
However, these isotherm parameters do have units. They depend on the units of other variables like component loading and concentration. For example, if you are using Langmuir isotherm:
The base unit of wi (loading) is g/litersolid or g/gsolid, then IP1 (saturation constants) should be litersolid/g or gsolid/g. The base unit of ci (component concentration) is g/liter, then IP2 (equilibrium constant) should be liter/g.
For more details, please read the topic of General Liquid Process: Explanation of Equation Symbols in Help menu.
Keywords: Isotherms
Model Parameters
Estimation mode
References: None |
Problem Statement: How do I enable GMULT for Aspen DMC3 controllers? | Solution: The procedure is as below:
1, open Aspen DMC3 Builder, locate your DMC3 controller project
2, find Model Parameters in Master Model tab in left Controller panel
3, check the 'Enable gain multiplier', select the MV/CV pairs which you are going to enable GMULT.
4, click OK to accept the changes
After the entry of GMULT has been enabled, user need redeploy this controller to make this change take effect. Now, you are able to see them in PCWS - controller - Model.
The value of gain multiplier can be changed through here.
Keywords: GMULT
DMC3 Builder
DMC3 Controller
References: None |
Problem Statement: How do I model a flare system using Aspen HYSYS Dynamics? | Solution: You can represent the flare system in Aspen HYSYS Dynamics as a combination of valve and pipe segment for multiple phase flow, but it will not consider the kinetic energy term in the temperature and pressure calculation. The calculation without including kinetic energy term results in a higher velocity and hence higher pressure drop across pipe.
This is because in Aspen HYSYS (Steady State and Dynamics), there is isenthalpic calculation across the valve and pipe segment uses frictional loss and elevation change.
For simulating a dynamic flare, the initial relief flow is close to zero, so at this stage the kinetic energy does NOT play a major role in the head/momentum balance. But once the flow increases (close to Mach number > 0.1), this effect is significant.
In Aspen Flare System Analyzer (or Aspen Flarenet), there is an option to include kinetic energy for enthalpy balance. However, Aspen Flare System Analyzer is limited to steady state modeling.
In Aspen HYSYS (Steady State and Dynamics), kinetic energy is not considered for pipe segment unit operation. To account for kinetic energy in Aspen HYSYS (Steady State and Dynamics) Aspen Hydraulics can be used. Aspen Hydraulics utilizes the kinetic energy in energy balance calculations.
Keywords: Flare System, Aspen Hydraulics, Kinetic Energy, pipe segment
References: None |
Problem Statement: What is the range of valid values for the output | Solution: in a PIMS-AO run?
Solution
During a PIMS-AO run the user may designate a number for the naming of the OutputSolution file created as shown below. Acceptable values for this are 1 to 65534.
If a value higher than 65534 is entered, then the run will fail with the messages shown below in the execution log.
This message will be in the XLPMGErrors.log file. This is resolved by changing the value to 65534 or lower.
Exception in Case Stacking:
Exception Message: Value was either too large or too small for a UInt16.
Exception StackTrace: at System.Convert.ToUInt16(Int32 value)
At Aspentech.SupplyChain.PIMS.PimsModelData.AODataServer.ModelDataHelper.ProcessCases(Int32[] nCases, String[] strModelGen, Int32 nSolutionDefault, Boolean bValidateOnly, Boolean bGenerate, Boolean bSolve, ValidateModelCase validateModelCase, ValidateCaseModifications validateCaseModifications, GenerateModel generateModel, CancellationToken cancelToken, String[]& strNewTables)
Keywords: None
References: None |
Problem Statement: Why does the specified fittings and valves count change in a plant bulk pipe component after changing the Pipe Routing Type? | Solution: This is a designed behavior in Aspen Capital Cost Estimator (ACCE) that allows the user to apply quick fitting count adjustment to all the piping associated to a specific type (e.g. Pipes in racks, AGR).
As soon as the user selects a Pipe Routing Type, ACCE will immediately search and apply the information in the “Fittings” Customer External File located on the Project Basis View. If no Fittings file has been selected yet, it’ll use information from the DEFAULT file.
Note that this new count does not overwrite the fittings and valves that were manually specified by the user in the pipe component form, but just represent additional fittings that are added due to this default rules.
If the user wishes to remove this automatically added fittings and valves, please review article 47038
Keywords: Fittings, Additional, Extra, Pipe, Valves, Automatic,AGU, AGR, UGU, MRP, OTP
References: None |
Problem Statement: This article describes about the procedure to scan selective tags in AspenOne process explorer Admin tool.
It is no more required to scan the entire database, even when only few tags are added to database. | Solution: When new tags are added in the Aspen InfoPlus21 database, it is mandatory to scan the new tags.
This is required for making the new tags appear in the AspenOne process explorer search engine.
As such, the entire database can be scanned through AspenOne process explorer Admin tool.
The steps below, however, are the guidelines for scanning selective tags. This will be beneficial to save time scanning the entire database, in case only few new tags are added to database.
To scan only selective tags, please follow the below process:
a. Open AspenOne process explorer Admin and navigate to Tags Tab.
b. In the Manage tags section, select the data source name.
c. In Specify how to scan your tags, select Tag Name from the drop down
d. Make sure to enter the tag names, separated by comma, in case there are more than one tag to be scanned. Select Add.
e. Once all the tags are added, select Scan Tags
After all the added tags are scanned successfully, these new tags will start appearing in the A1PE search page and trend search.
Keywords: Tag scan in A1PE
A1PE admin
Selective tag scan
References: None |
Problem Statement: How to change Oracle client’s language setting on the APS machine for EIU to work ?
EIU doesn’t work for ORACLE when NLS_LANG setting is different with OS language.
Background:
1．NLS_LANG setting of Oracle
NLS_LANG is set in the registry on Windows platforms.
The NLS_LANG parameter has three components: language, territory, and character set. Specify it in the following format, including the punctuation:
NLS_LANG = language_territory.charset
Language
Specifies conventions such as the language used for Oracle messages, sorting, day names, and month names. Each supported language has a unique name; for example, AMERICAN , FRENCH , or GERMAN . The language argument specifies default values for the territory and character set arguments. If the language is not specified, then the value defaults to AMERICAN .
Territory
Specifies conventions such as the default date, monetary, and numeric formats. Each supported territory has a unique name; for example, AMERICA , FRANCE , or CANADA . If the territory is not specified, then the value is derived from the language value.
Charset
Specifies the character set used by the client application (normally the Oracle character set that corresponds to the user's terminal character set or the OS character set). Each supported character set has a unique acronym, for example, US7ASCII , WE8ISO8859P1 , WE8DEC , WE8MSWIN1252 , or JA16EUC . Each language has a default character set associated with it.
The default language should match with OS language, but IS may change it.
2. EIU use ORACLE tool SQL Loader to import batch data file to database, execution result of SQL Loader is impacted by the NLS_LANG setting. EIU set the change batch data numeric format according the OS language, if user change Oracle client’s language setting, EIU failed to import data to ORACLE. | Solution: TheSolution for the issue is to change Oracle client’s language setting on the APS machine.
The following are the steps to change the client's language setting for an APS machine:
Open Registry on your machine which installed both APS and Oracle client.
Edit the following registry entry:
For Oracle version 7:
HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE
For Oracle Database versions 8, 8i and 9i:
HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\HOMEx\
where x is the unique number identifying the Oracle home.
HOME0 is the first installation
For Oracle Database 10g or later version:
HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\KEY_<oracle_home_name>
There you have an entry with name NLS_LANG,
Change the NLS_LANG to the default setting of OS language.
Operating System Locale NLS_LANG Value
Arabic (U.A.E.) ARABIC_UNITED ARAB EMIRATES.AR8MSWIN1256
Bulgarian BULGARIAN_BULGARIA.CL8MSWIN1251
Catalan CATALAN_CATALONIA.WE8MSWIN1252
Chinese (PRC) SIMPLIFIED CHINESE_CHINA.ZHS16GBK
Chinese (Taiwan) TRADITIONAL CHINESE_TAIWAN.ZHT16MSWIN950
Chinese (Hong Kong HKCS) TRADITIONAL CHINESE_HONG KONG.ZHT16HKSCS
Chinese (Hong Kong HKCS2001) TRADITIONAL CHINESE_HONG KONG.ZHT16HKSCS2001 (new in 10gR1)
Croatian CROATIAN_CROATIA.EE8MSWIN1250
Czech CZECH_CZECH REPUBLIC.EE8MSWIN1250
Danish DANISH_DENMARK.WE8MSWIN1252
Dutch (Netherlands) DUTCH_THE NETHERLANDS.WE8MSWIN1252
Dutch (Belgium) DUTCH_BELGIUM.WE8MSWIN1252
English (United Kingdom) ENGLISH_UNITED KINGDOM.WE8MSWIN1252
English (United States) AMERICAN_AMERICA.WE8MSWIN1252
Estonian ESTONIAN_ESTONIA.BLT8MSWIN1257
Finnish FINNISH_FINLAND.WE8MSWIN1252
French (Canada) CANADIAN FRENCH_CANADA.WE8MSWIN1252
French (France) FRENCH_FRANCE.WE8MSWIN1252
German (Germany) GERMAN_GERMANY.WE8MSWIN1252
Greek GREEK_GREECE.EL8MSWIN1253
Hebrew HEBREW_ISRAEL.IW8MSWIN1255
Hungarian HUNGARIAN_HUNGARY.EE8MSWIN1250
Icelandic ICELANDIC_ICELAND.WE8MSWIN1252
Indonesian INDONESIAN_INDONESIA.WE8MSWIN1252
Italian (Italy) ITALIAN_ITALY.WE8MSWIN1252
Japanese JAPANESE_JAPAN.JA16SJIS
Korean KOREAN_KOREA.KO16MSWIN949
Latvian LATVIAN_LATVIA.BLT8MSWIN1257
Lithuanian LITHUANIAN_LITHUANIA.BLT8MSWIN1257
Norwegian NORWEGIAN_NORWAY.WE8MSWIN1252
Polish POLISH_POLAND.EE8MSWIN1250
Portuguese (Brazil) BRAZILIAN PORTUGUESE_BRAZIL.WE8MSWIN1252
Portuguese (Portugal) PORTUGUESE_PORTUGAL.WE8MSWIN1252
Romanian ROMANIAN_ROMANIA.EE8MSWIN1250
Russian RUSSIAN_CIS.CL8MSWIN1251
Slovak SLOVAK_SLOVAKIA.EE8MSWIN1250
Spanish (Spain) SPANISH_SPAIN.WE8MSWIN1252
Swedish SWEDISH_SWEDEN.WE8MSWIN1252
Thai THAI_THAILAND.TH8TISASCII
Spanish (Mexico) MEXICAN SPANISH_MEXICO.WE8MSWIN1252
Spanish (Venezuela) LATIN AMERICAN SPANISH_VENEZUELA.WE8MSWIN1252
Turkish TURKISH_TURKEY.TR8MSWIN1254
Ukrainian UKRAINIAN_UKRAINE.CL8MSWIN1251
Vietnamese VIETNAMESE_VIETNAM.VN8MSWIN1258
For more detail about NLS_LANG, please refer to http://www.oracle.com/technetwork/database/database-technologies/globalization/nls-lang-099431.html
Keywords: None
References: None |
Problem Statement: In AFR V10, is there any option to easily assign multiple events from the Unit Diagram to existing events in the RAM data? | Solution: Starting in V10 CP3, we have the Event Assignment feature which allows user to assign multiple events from the Unit Diagram to existing events in the RAM data. The Event Assignment button on the Home ribbon | Customization group is only available when an event or events in a unit diagram are selected. Clicking the Event Assignment button opens the Assign Events window. The Assign Events window allows you to assign existing events in the RAM Data environment to any events in the unit diagram. To select multiple events, you can either Ctrl-click events or click-and-drag to select multiple events. Non-event unit elements, such as the rate multiplier, selected from the click-and-drag method are ignored in the Assign Events window.
Key words
Event Assignment
Keywords: None
References: None |
Problem Statement: The Dynamics Assistant indicates a message saying Tray section dry hole pressure drop too large, what does that mean? | Solution: The vapor Pressure/Flow relation through the column is calculated using a valve-like P/F relation using a K factor for each and every tray:
Where:
Fvap = vapor flowrate leaving tray N
k = conductance, which is a constant representing the reciprocal of resistance to flow. (For columns the conductance, k, is proportional to the square of the column diameter.)
ΔP friction = dry hole pressure drop
The pressure drop across a stage is determined by summing the static head and the frictional losses.
The reason for such a message Tray section dry hole pressure drop too large is either because the vapor flow is too high relative to the design case, resulting in too much pressure drop, or because the K values for the trays are too low.
Since the K values are actually based on the column diameter, the dynamic assistant will always suggest a larger diameter to get rid of the problem. But if you are bound by existing column dimensions, the tower diameter is not a variable you can change at will, so you can change the K factors directly instead. This can be done in the Tray Section window, Dynamics Tab |Specs page (inside the column environment).
You should always try to have a steady model at the normal flows and conditions before attempting to adjust the K factors. This will allow you to match your existing plant operation or steady state model.
Keywords: Column Hydraulics, Dry Hole Pressure Drop, Tray Section
References: None |
Problem Statement: For the Reflux Ratio Spec, what does the Include Vapour checkbox mean ? | Solution: For a Condenser with the following products
V = Vapour product
D = Distillate product
R = Liquid Reflux to column
If Include Vapour is checked then
Reflux Ratio = R / (V + D)
If it isn't
Reflux Ratio = R / D
Hence if the Condenser has no vapour product (ie a Total Condenser) then it doesn't matter if this checkbox is checked.
Keywords: Column, Reflux Ratio, Include Vapour
References: None |
Problem Statement: How do I change the materials of the Air Supply items in Aspen Capital Cost Estimator? | Solution: The air supply materials generated on a piping component are by default added into the estimation considering galvanized steel (GALV) for the fittings and pipes, and naval brass (BRASS) for the valves included.
This default configuration cannot be changed or controlled from the regular ACCE interface.
If you wish to change the material of each individual item, then it’s necessary to run the DURE (Detailed Unit Rate Estimating) reports.
After running the DURE report, use the filter to sort out COA 631 (AIR SUPPLY PIPING), you will be able to change the value under the Material column to any input acceptable in ACCE.
Once this change has been implemented, import the modified DURE file into ACCE and run the evaluation.
To read more about DURE, please refer to theseSolutions:
Jump Start: Detailed Unit Rate Estimating in Aspen Capital Cost Estimator
Using Detailed Unit Rate Estimating
Keywords: air supply, instrumentation, piping, DURE, material, fittings
References: None |
Problem Statement: Does the valve account for sonic flow/ choking in Dynamics? | Solution: The valve does model choking. However, you must use the Cv option and not the k option (Simple resistance equation).
If you add a pipe segment in the valve, then note that the pipe segment contribution does NOT model choking.
Keywords: Cv, k, Choking, Sonic
References: None |
Problem Statement: What can prevent me from running Activated Economics in Aspen Plus? | Solution: When the Aspen Plus simulation presents any Error, the Activated economics features will not be available.
It is important for Activated Economics to be able to read all the simulation data from all the blocks in order to correctly Map and Size all of them and correctly estimate them. When errors are present in one or more blocks or in the overall convergence of the simulation, Activated Economics will be disabled to prevent further problems in the estimation.
Once all the simulation errors have been resolved, the user can run the simulation once again and verify that the Economics Ribbon becomes enabled, allowing the user to estimate his process.
If the Aspen Plus simulation does not have any errors and the options are still grayed out, there could be a compatibility issue between Aspen Plus and Aspen Process Economic Analyzer, please review article 46873 for more information on this.
Keywords: Error, Grayed out, Disabled, Economics, Send to APEA
References: None |
Problem Statement: How to import simulation data from Aspen Plus in English (ENG/IP) units into Aspen Process Economic Analyzer? | Solution: There are several ways of importing Simulation information from Aspen Plus into Aspen Process Economic Analyzer (APEA), such as clicking “Send to APEA” from the Aspen Plus interface or selecting a simulation file from the Project basis section of an APEA file.
However, these two options transfer information directly from the Aspen Plus BKP or APW file using Metric (IS) units, regardless of the configurations in the APEA file or the units selected in the Aspen Plus file, meaning that all the information under the Process view tab will show the information in Metric units.
This may not be a significant issue, since this information is only used to map and size the simulation items and transfer them to the Project View section, and once transferred, the components will convert the data successfully to English units.
The main inconvenience is that some reports, such as the item HTML report, can display the original simulator data, which will still show in Metric units.
To allow the information to be imported in ENG units, the Aspen Plus file should be configured to use ENG units and the user should then export an XML file from Aspen Plus. This XML file can be imported into an APEA project and will successfully transfer the data in English units
Keywords: ENG, IP, Process View, Units, Import, Send to APEA.
References: None |
Problem Statement: For Steam Header “FixImbalanceFlow” variable, which option to select? | Solution: The “FixImbalanceFlow” variable lets user select either “True” or “False” option. If True is selected, user must specify the steam/water imbalance flowrate. If False is selected, then the flow imbalance is calculated as Free variable based on the feeds to and demands from the steam header.
Please note that when option “True” is selected, the “Flmbalance” variable becomes Fixed and a value can be assigned.
Key Words
Steam Header, FixImbalanceFlow, Fixed, Free
Keywords: None
References: None |
Problem Statement: In Aspen HYSYS, the Cold Properties utility includes several methods to estimate the Reid Vapor Pressure, what is the difference of each one of them? | Solution: First, to access to the Cold Properties, the user can select the Analysis section of the Attachments Tab from a Stream and click on create.
On the following window, the user can select Options button and display the several methods to estimate Reid Vapor Pressure.
This list includes the following correlations:
ASTM D323-73/79: This correlation is also known as P323. The pressure is adjusted at the RVP reference temperature until the vapour to liquid ratio is 4:1 by volume. This correlation is essentially the same as the Reid VP at 37.8 °C correlation, except it is not on a dry basis and the flash method used is the same for the rest of the flowsheet.
Aspen RVP-API: This correlation is applicable for stream having True Vapor Pressure less than 25 psia. A proprietary correlation is used which assumes RVP as a function of True VP.
API 5B1.1 (Naphtha): This property correlation is useful for gasoline and finished petroleum products, but not crude or oxygenated blends. The TVP is correlated against the RVP, temperature, and slope of the ASTM D86 distillation curve at the 10% point. This property solves the corrected version of the API databook equation of the correlation for the RVP. A recognized limitation of the API Naphtha correlation is that the D86 10% point can have a similar gradient for vastly different streams.
API 5B1.2 (Crude): This property correlation is generally used for condensate and crude oil systems (typically wide boiling preprocessed hydrocarbons). TVP is correlated against RVP and the temperature. This property solves the API databook equation of the correlation for RVP. The correlation is based on data from 1959, but it is popular with engineers for its quick and dirty calculations.
ASTM D323-82: This is the standard and accepted procedure for RVP lab measurement. Liquid hydrocarbon is saturated with air at 33?F and 1 atm pressure. Since the lab procedure does not specify that the test chamber is dry, the air used to saturate the hydrocarbon is assumed to be saturated with water. This air-saturated hydrocarbon is then mixed with dry air in a 4:1 volume ratio and flashed at the RVP reference temperature, such that the total volume is constant (since the experimental procedure uses a sealed bomb). The gauge pressure of the resulting mixture is then reported as the RVP.
ASTM D4953-91: This correlation is for oxygenated gasoline. It is the same as the D323-82 test method, except everything is on a completely dry basis (in other words, the air is not saturated with water).
ASTM D5191-91: This was developed for gasoline and gasoline-oxygenate blends as an alternative to the D4953-91 test method. In the experimental procedure, the hydrocarbon is saturated with dry air and then placed in an evacuated bomb with five times its volume. The total pressure is then converted to a dry vapour pressure equivalent (DVPE) and reported as the RVP. The method used is to mix near vacuum air at 0.01 psia and 100 °F with hydrocarbon at 1 atm and 33 °F in the ratio 4:1. This is then flashed at constant volume at the RVP reference temperature. The pressure is then converted to a DVPE and reported as the RVP.
ASTM D6377-16: This correlation can also be used for ASTM D323-15a and ASTM D6378-10. The main feature is that the Vapor/Liquid Volume Ratio can be changed. When you adjust this value, the RVP will be recalculated automatically. This method is suitable for testing crude oil (live and dead oils) samples that exert a vapor pressure between 25 and 180 kPa at 37.8 °C at vapor-liquid ratios from 4:1 to 0.02:1. A vapor-liquid ratio of 0.02:1 closely mimics the situation of an oil tanker. In addition, this method is applicable to crude oil samples with pour points above 0 °C.
Note: HYSYS RVP correlation is no longer available and now the default method is ASTM D323-73/79 in wet Basis (HYSYS RVP used this standard, but was in dry basis).
Keywords: Cold Properties, Utility, RVP, ASTM correlation, API methods
References: None |
Problem Statement: When I send data from Aspen Flare System Analyzer to MS Excel by clicking the Excel button on the Results forms, arithmetical formulas cannot be used in Excel | Solution: When you transfer information from Aspen Flare System Analyzer using the Excel button, the application will simply perform a Copy/Paste operation from the Flare interface to MS Excel.
This however, causes the values transferred to Excel to be considered as Text, rather than as numbers that can be used in arithmetical formulas available in Excel.
To workaround these behavior, you can use the tools built in MS Excel to convert the data to numbers. Place the cursor of the mouse near the green corners of the cells in Excel and select “Convert to Number”, this will enable the cells to be used in arithmetic formulas.
Keywords: Excel, Results, Input, Number, Formula, Export
References: None |
Problem Statement: Does AFR validation feature only represent the state at Time Zero? | Solution: Although, default validation represents the state at zero, it is not the only state that it can represent. For example, an event can be activated or de-activated. A tank’s currently level can be modified. So, in short, it is a single point in time, but you are allowed to setup the current state of the model for that single point in time.
Key words
validation
Keywords: None
References: None |
Problem Statement: This | Solution: describes how to populate a csv file with work orders for import by Aspen Mtell when using the MIMOSA CRIS DB open standard choice of EAM adapters.Solution
First, generate a blank csv import template. This can be done with the following steps: 1) Open the Aspen Mtell Agent Builder, 2) Click on the “Failure Library” tab, 3) Click on the “Import Work Items” button in the ribbon, 4) Specify the name of a new file in the “File” option, and 5) Click on the “Generate Import Template” button at the bottom left of the screen. Once this is done, a blank template file specified in step 4 will be generated for inputting work orders.
Next, open the csv file using Microsoft Excel and fill out the columns with the appropriate values. Each row in this Microsoft Excel file should represent a different work order. Before importing the work items back into the Aspen Mtell Agent Builder, make sure the fields “Enterprise ID”, “Site ID”, “Object ID”, “Object Types”, “Work ID”, “Created Date”, “Title”, and “Type”. If the work order is a known failure, the “Is Breakdown” and “ReliabilityGroupId” fields should also be filled out.
Keywords: CSV work orders
References: None |
Problem Statement: Every time you launch an AspenTech program, the splash screen is shown with the product name, product version and the product family. Some programs also display the status of the program startup at the bottom of the splash screen.
It is recommended that the splash screen should be displayed for all users, there are cases where a system administrator may want to disable the splash screen in a particular environment. This knowledge base article describes how to disable the splash screen for all AspenTech products on a given computer.
Note: Disabling the splash screen will not decrease the time required for the program to open. | Solution: To disable the splash screen, open a Command Prompt with the Run as Administrator option.
Navigate to the AspenTech Shared folder by typing: cd C:\Program Files (x86)\Common Files\AspenTech Shared and press Enter.
Type the command: AspenSplash.exe -unregserver and press Enter.
To re-enable the splash screen type the command: AspenSplash.exe -regserver and press Enter.
Note: The splash screen will be disabled for all products on the computer. Also, no AspenTech products will appear in the Aspen One toolbar after the splash screen has been disabled.
Keywords: Splash Screen
References: None |
Problem Statement: Why are the pH stream results not shown in Aspen Plus even if I have acids and hydroxides on my component list? | Solution: When you add pH results to the results summary of Aspen Plus, it’s important to mention that pH results are only calculated and reported for the liquid phase of a stream, so you may have to expand the Liquid Phase results to see this data. For the case of streams that are full vapor, pH will not be calculated since the liquid fraction is 0.0.
After ensuring that the stream you are viewing has a liquid phase, it’s also important to note that the acid/ hydroxide components must be correctly specified on the Properties Environment. This means that not only the acid (e.g. HCL) or the hydroxide (e.g. NAOH) should be present on the component list but the associated ions and dissociation chemistry of these must be defined in this environment.
This is important since the properties of these ions allow for pH calculation. The details on how pH is calculated in Aspen Plus are shown in the article pH Calculations.
An easy way of configuring this information in the Properties environment when using Acids/Bases in Aspen Plus is to use the Electrolyte Wizard on the Components | Specification form
The Electrolyte Wizard will guide you through a series of simple steps which include selecting which components will be dissociated in the simulation, selecting the possible dissociation reactions and choosing a property method to handle the electrolytes (e.g. ELECNRTL).
After completing these steps, based on the reactions you chose, the wizard will automatically add the Ion components that will be present in your simulation as well as the chemistry of the simulation, allowing the ion dissociation to be evaluated in the simulation.
With all these steps complete, run the simulation once more and verify the pH results should not be empty anymore.
Keywords: Empty, Blank, Electrolytes, pH, H3O+, OH-, Summary, Report
References: None |
Problem Statement: Why reverse flow in heater model causing dynamic run fail? | Solution: Heater model supports reverse flow. However most of the times, the heat transfer options in heaters are selected as “Constant Duty” which may cause thermal convergence in reverse flow situations. In forward flow mode, if flow rate goes down then constant duty option drives the temperature of process fluid to its upper bound. However, a built-in script procedure in dynamics ramps down the duty to zero so that temperature falls back in bound.
In case of reverse flow, this procedure fails to bring constant duty to zero, so overshoot of temperature can cause dynamic solver to fail.
To avoid this issue, its recommended to use Constant temperature or LMTD Heat Transfer options.
Key Words
Reverse Flow, Heat Transfer, LMTD, Constant Duty
Keywords: None
References: None |
Problem Statement: Aspen Connect fails to connect to the Azure IoT Hub. As a result, publishing of data to Azure IoT Hub using OPCUA on the IOT Hub configuration returns the error- “Microsoft Azure did not accept the IoT Hub Connection Request” | Solution: 1. Using Windows Explorer, navigate to the folder “C:\ProgramData\AspenTech\CertificateStores\RejectedCertificates\certs”
Note: Folder location C:\ProgramData\ might be different between computers. You can get the correct ProgramData location on a computer by opening a command prompt (DOS) and running the command ECHO %ProgramData%
2. Move the file “+.azure-devices.net […].der” by right mouse clicking and select Cut from the context menu or highlight the file and press Ctrl+X
3. Navigate to the folder “C:\ProgramData\AspenTech\CertificateStores\UA Applications\certs” and paste the cut file in there by pressing Ctrl+V or right clicking in the folder contents and selecting paste from the context menu.
4. Using the Aspen Connect Toolkit, validate the connection to IOT Hub using OPC UA by clicking on the Test button in the IoT Hub Configuration dialog box – Test connection should be successful.
Keywords: Aspen Connect Set-up Tool
IOT Hub
Microsoft Azure
References: None |
Problem Statement: In a control valve, when I select Manufacturer specific methods under Rating tab | Sizing page C1 factor is available. What is this factor and how do I establish its appropriate number? | Solution: C1 is defined as the ratio of the gas sizing coefficient and the liquid sizing coefficient (Cg/Cv) and provides a numerical indicator of the valve’s recovery capabilities.
To maintain a steady flow of liquid through the valve, the velocity must be greatest at the vena contracta, where cross sectional area is the least. Farther downstream, as the fluid stream expands into a larger area, velocity decreases and pressure increases. But, of course, downstream pressure never recovers completely to equal the pressure that existed upstream of the valve.
A valve with a high-recovery capability dissipates relatively little flow-stream energy due to streamlined internal contours and minimal flow turbulence. Therefore, pressure downstream of the valve vena contracta recovers to a high percentage of its inlet value. On the other hand, a low-recovery valve dissipates a considerable amount of flowstream energy due to turbulence created by the contours of the flowpath. Consequently, pressure downstream of the valve vena contracta recovers to a lesser percentage of its inlet.
In general C1 values can range from about 16 to 37, depending on whether the valve is high recovery (16) or low recovery (37). HYSYS' default is 25, which is close to the mean of this range.
More information can be found here about C1 factor, Cv and Cg:
http://www.documentation.emersonprocess.com/groups/public/documents/reference/d351798x012_11.pdf
Keywords: C1 factor, high and low recovery, sizing methods
References: None |
Problem Statement: How do I enable Time Constant and Variable Deadtime for Aspen DMC3 controllers? | Solution: The procedure is as below:
1, open Aspen DMC3 Builder, locate your DMC3 controller project
2, find Model Parameters in Master Model tab in left Controller panel
3, in the new dialog, we can see Gain Multiplier, Time Constant Multiplier and Variable Deadtime. Once enabled, these options allow APC engineers make
small tunings to online controller without redeploying and turning off controller.
4, click OK to accept the changes.
After the entry of Time Constant Multiplier and Deadtime have been enabled, user need redeploy this controller to make this change take effect.
Now, you are able to see them in PCWS - controller - Model. The default value is 1 for time constant and 0 for deadtime, which means
the time constant and deadtime of this MV/CV response curve hasn't been modified for online control.
Keywords: Time Constant
Deadtime
DMC3 Builder
DMC3 Controller
References: None |
Problem Statement: How are critical properties calculated for a stream? | Solution: There are two sets of critical properties reported for a stream in Critical Property Analysis: Pseudo and True critical properties.
The Pseudo critical properties are simply the summation of the apparent contributions of each pure component. For example, the pseudo Tc of a binary mixture (component 1 and 2) would be calculated as Tc=x(1)*Tc(1)+x(2)*Tc(2).
The True critical properties are the real critical properties of the stream determined thermodynamically by satisfying both the quadratic and cubic forms in the expansion of the Helmholtz free energy as a function of the mole numbers as zero at a critical point. Details of critical point calculations can be found in the paper by Heidemann and Khalil (AIChE Journal, Vol. 26, No.5, p769-779, 1980).
Keywords: Critical Properties, Tc, Pc, Pseudo Critical Properties, True Critical Properties.
References: None |
Problem Statement: How to create Ad-hoc Calculations in A1PE? | Solution: AspenONE Process Explorer can display the results of an Ad-hoc calculation as a pen on the trend plot
Benefit – no need to create extra tags inside the Aspen InfoPlus.21 database to hold results
* Ad-hoc – a Latin phrase meaning “for this purpose only”.
To create an Ad-hoc calculation, type your calculation in the Add to Plot… field.
The calculation always begins with the ‘=‘ sign.
If necessary, select the appropriate data source from the list box provided.
The screenshot above above shows the result of the calculation =ATCTIC301 + ATCAI
Notice that the Description column contains the text Ad Hoc Calculation.
You may have to switch the Scale to Auto in the Legend to make the plot visible.
The screenshot above shows an example of IF..THEN..ELSE expressions.
=IF ATCL101 > 5000 THEN ATCL102
If the current value of ATCL101 is above 5000 then the current value of ATCL102 is plotted. If this expression evaluates to False, then ATCL101 itself is displayed.
Keywords: Ad-hoc calculation
A1PE
References: None |
Problem Statement: How can I access the phase specific information of a stream such as transport properties (viscosity, thermal conductivity, etc.) via OLE? | Solution: To access a phase, you must first obtain a Fluid object for the stream. This can be accomplished by using the .DuplicateFluid() method of the ProcessStream object.
Accessing properties of the phase can actually be accomplished in a single line. Here is an example of code which will start from the ProcessStream object and determine the vapour phase viscosity:
vapvisc=myProcessStream.DuplicateFluid().VapourPhase.ViscosityValue
Note that vapvisc will be a double and myProcessStream must be properly defined. Also, this line will obviously fail if your fluid does not contain a vapour phase. You will have to add the appropriate checks to determine if a vapour phase is present.
Keywords: Fluid, Phase, DuplicateFluid,VapourPhase
References: None |
Problem Statement: How can I attach a stream to more than one operation? | Solution: By default, HYSYS does not allow a stream to be connected to more than one operation (this is particularly important to avoid potential difficulties caused by material balance problems).
However it can be set to allow this:
Go to the File menu | Options | Simulation | General Options and check the Allow multiple stream connections checkbox.
Examples of when this might come in useful:
Attaching a balance operation to a stream to calculate a dew point (Mole Balance - Vapour fraction of outlet stream = 1)
Using the Gas Props extension on a stream that is neither a feed nor product from the process.
Keywords: Allow multiple stream connections
References: None |
Problem Statement: How to account for changes in pH rather that ion gradient in Ion Exchange Chromatography? | Solution: Aspen Chromatography does not do rigorous chemical equilibrium calculations. You can use a custom isotherm and as part of the custom isotherm call the pTrueComp procedure to get the equilibrium composition and calculate PH from there. Note, this requires configuring Aspen Properties and converting from equivalents per liter to mole-fraction.
Key Words
Ion Exchange, PH, Equilibrium
Keywords: None
References: None |
Problem Statement: Results are inconsistent when running the same simulation multiple times. How to fix the problem? | Solution: A common cause is that the variables were not initialized to the same set of values before each run. This can occur in these situations:
It can occur if the simulation was not rewound after a previous dynamic run. Rewind each time.
Alternatively, if the simulation is saved and closed at time > 0, the values at that time (in the middle of a dynamic run) will stay in place. When the simulation is reopened, the time will be set to 0, but the values from the middle of the dynamic run will still be in place. Always rewind before saving and closing a simulation.
If a variable value or structural change is made during a dynamic run, rewind to time = 0, make any changes, and reinitialize. (Reinitializing will generate a new snapshot of initial conditions, which will be used when rewinding the changed simulation.)
Keywords: Adsorption, rewind
References: None |
Problem Statement: Which of the AFR parameters are used for validation only? | Solution: In Aspen Fidelis Reliability, parameters can either be used in both simulation run and model validation or are limited to either simulation run or model validation. The table below displays all elements and categorizes each element parameters as simulation only, validation only, or both for reference. All parameters that are classified as validation only in the Aspen Fidelis Reliability GUI can be used in the simulation run by invoking the features in the write key routines.
Key words
parameters, validation
Keywords: None
References: None |
Problem Statement: How to activate Aspen Utilities Planner Microsoft Excel Add-in? | Solution: Please follow the following steps to activate the Utilities Planner Add-in in Excel:
1. Please open an Excel blank file and go to File > Options
2. Select Add-Ins > Manage: Excel > Add-Ins > Go
3. And select the Utilities 360.xla file from the following location:
This will complete the activation of Aspen Utilities planner Excel Add-In.
Key Words
Add-In, Active, Utilities Planner
Keywords: None
References: None |
Problem Statement: How to model coating for an Air Cooled Heat Exchanger in EDR? | Solution: For Air Cooled Heat Exchangers that operate near the coast, corrosion due to sea water is a common problem. In such cases, coating is applied to the external surface of the ACHE as protection to prevent such issues.
In EDR, there isn’t a specific input to add coating. However, if we consider that this coating will represent an additional resistance to heat transfer, this can be accounted for as an outside fouling resistance.
This fouling resistance could be specified directly, or it could be calculated by EDR based on the layer thickness (of coating) and its thermal conductivity (inputs that are more likely to be available).
This information can be specified under Input | Problem Definition | Process Data | Outside Fouling:
Keywords: Coating, air cooler, fouling
References: None |
Problem Statement: Internal streams for Distillation Column have different information than external streams | Solution: There can be two different scenarios where an internal stream inside the Column Environment can display different results for process data and stream properties than those reported in the external stream:
When exporting an Internal Stream created by taking the top stage vapor phase: it is expected that its temperature may not be the same as the temperature of the stream between the top stage and the condenser. The first thing that we should note is that it is generally not a problem with the transfer basis. The internal stream on the inside of the column subflowsheet is the same as the corresponding stream on the outside, so you do not see any change when changing the Transfer Basis (say from PT Flash to PH Flash). To see confirmation that the outside stream is solving switch the trace window to verbose and then change the transfer basis. You will see that the external stream solves fine.
The difference may be due to tray efficiencies that have been set to something other than the default value of 1.0: When defining an efficiency for a stage, the VLE inside the column environment considers this deviation for its calculations; whereas the VLE done on the stream in the Main Environment uses the Internal Stream Enthalpy and Pressure to perform a PH Flash, from which it recalculates the temperature and vapor fraction. Whenever you specify an efficiency in a column, this behavior will be seen. The only thing that can be changed is the flash being performed, (switch from PH to a PT flash for example), and now the temperature and pressure will be the same, but the enthalpy will be different.
In other words, the internal stream considers the efficiency and the external one just recalculates the flash calculations based on the internal stream values.
Basically, when the tray efficiency (for any tray) is set to be 1, then the drawn stream (vapor or liquid) from that tray will have the same temperature as the internal stream (vapor or liquid). If the tray efficiency is not 1, then the temperature for the drawn stream (vapor or liquid) is calculated by the column and the temperature for the internal stream (vapor or liquid) is calculated by performing a P-VF flash.
Keywords: Internal, external, streams, efficiency, column
References: None |
Problem Statement: How do I remove the fittings and valves added automatically by the Pipe Routing Type? | Solution: As mentioned in article 47037, when the user selects a Pipe Routing Type, ACCE will look for information in the Fittings file.
If the user wants to eliminate this additional fittings and valves, the Fittings file must be modified.
In the Project Basis View, locate the Fittings form under the folder Customer External Files.
If no customization has been previously done to this file, right click on Fittings and choose Select, then select the DEFAULT rules file to be able to view it and edit it.
After loading the rules file, right click again on Fittings and click Edit.
The Fittings file allows the user to customize the rules to automatically assign certain fittings to piping components, so new fittings can be added automatically to pipes per each 100 FT of length. These rules can be different for each available Pipe Routing Type (AGU, AGR, UGU, MRP and OTP).
Note that the count of additional fittings and valves can be specified separately, notice as well that counts for fittings and valves can be controlled for pipes of different diameter ranges, even if they use the same routing type.
If the user wishes to remove these new added fittings, he/she can replace the default numbers in the Fittings file in one or more Routing Types by replacing the default values with “0 “ (0 plus a blank space) to all the applicable fields that are currently in use.
For example, if the user is only defining some pipes as AGR (Pipes in rack) and wants to remove the additional fittings and valves for this, this can be changed like this:
Save and close the fittings form when done and re-evaluate the project, the new results should not include these additional fittings since the customized rule does not include any.
Keywords: Delete, Remove, Fittings, Valves, External, Zero
References: None |
Problem Statement: “PD-# VOLTAGE SPECIFIED IS LESS THAN MINIMIM”
What does this error mean and how can I resolve it? | Solution: This error can appear when the user manually specifies the Supply Voltage on one of the Main Substations or in the main Transmission line (Primary Voltage spec) under the Project Basis | Power Distribution tree form.
Aspen Capital Cost Estimator (ACCE) always evaluates the required power for the project based on the amount and size of components present in it that require power (e.g. Motors, Pumps). This required power is understood by the program as the minimum power value that the entire project needs, and if the user were to enter any power lower than this, the error will appear.
The user can see what this minimum Supply Voltage/Primary Voltage is by running an evaluation without voltage specs on the Power Distribution tree. After running this evaluation, the user can review the CCP report and look for the ELECTRICAL DESIGN DATA/Transmission Voltage section.
To solve this error message, the user should just review the minimum voltage that ACCE estimates for the project and then manually enter a Supply voltage equal or greater than this number.
Keywords: Error, Transmission, Voltage, Minimum, Power, Electric, Supply, PD, Power Distribution
References: None |
Problem Statement: What is Ramp rate and how it is used in Aspen DMC plus/DMC3 controller application? | Solution: Ramp rate is the dynamic tuning parameter for Aspen APC (DMCplus/DMC3) controller application, which is the forcing function that drives the ramp variable back towards the operator-entered RAMPSP, from current value.
Ramp Rate application for APC controller
Ramp rate and ramp set point are used to calculate the error minimization set point for Ramp variables.
The equation depicts how the error minimization set-point is calculated -
Error minimization SP= RampSetpoint * RampRate + (1.0 - RampRate) * X
where:
X = Measurement,
if OperatorLowLimit £ Measurement £ OperatorHighLimit
X = OperatorLowLimit,
if Measurement < OperatorLowLimit
X = OperatorHighLimit,
if Measurement > OperatorLowLimit
Possible values of Ramp Rate and Significance
a. Ramprate = 1.
This means the controller will move MV to take ramp to ramp SP.
In this case, the error is minimized = 100%
b. Ramprate = 0
This means controller will not move MV at all.
In this case, the error is minimized = 0%
c. Ramprate = 0.1
This mean controller will move the key MV to take Ramp to [rampsp+0.1*(measurement-RampSP)
In this case, the error is minimized = 10%
Keywords: Ramp Rate
Ramp Set point
Error minimization
Ramp Variables
References: None |
Problem Statement: Is it possible to run Aspen Flare System Analyzer through Excel Automation? | Solution: As with many other AspenTech programs, Aspen Flare System Analyzer (AFSA) is indeed compatible with VBA in Excel and can be used to generate customized interfaces.
However, one key difference when comparing AFSA with other applications such as Aspen HYSYS is that the Flare interface is not visible from VBA.
If you are running an AFSA model and choose to use VBA coding to perform changes in this same model (e.g. modifying inputs), you will not see applied of these changes to your current AFSA simulation.
This happens because VBA does not have access to the main Flare Application (AspenFlareSystemAnalyzer.exe) nor the GUI of the program, instead, VBA only accesses the Flare engine (FlarenetComServer.exe) which runs on the background when the code executes.
Since the Flare internal engine does not have any GUI, you won’t be able to use VBA to open the Flare window (GUI) as you would with other applications.
However, the Flare Engine does allow you to access and run a Flare model, so you can use VBA to extract scenario results, customize reports, run case studies, etc. and place these results in Excel cells.
Examples of VBA applications in AFSA can be found on the folder C:\Program Files (x86)\AspenTech\Aspen Flare System Analyzer VX.X\Samples\Ole\Excel
Keywords: OLE, Automation, VBA, Excel, Interface, Open, Launch, Run, File, ComServer
References: None |
Problem Statement: How can I set different Fluid Packages for my Sub-Flowsheets? | Solution: In the Home tab, you should be able to see, on the Simulation section, the Fluid Packages button. When you click on it a list of all flowsheets involved in the simulation will appear. Pick the desired flowsheet and use the drop-down menu to select a Fluid Package.
By default, all Flowsheets share the same Fluid Package used for the Main Flowsheet.
Example: Suppose that you want to use a special Fluid Package for a Column Sub-Flowsheet. Since the default Fluid Package for any Sub-Flowsheet is the Main Flowsheet's Fluid Package, in this case you must create your special Fluid Package and attach it to the column Sub-Flowsheet to replace the default package.
Keywords: Multi-fluid package, Different Fluid Package, Sub-Flowsheet.
References: None |
Problem Statement: What does the following warning mean and how can I solve it?
“End stage not specified for CS - # in Main Tower of column T - # # #!” | Solution: This message simply indicates that the information for column internals is currently incomplete. Specifically, this means that the “End Stage” for a specific Internals Section was left incomplete, the message also points towards the Column name (T - 301 in this example) and the Internals Section of this unit (CS - 2).
When using column internals, it is important to define how many different sections will the column have, and which stages of the column form each section by entering the Start and End stage of the section. Leaving any End Stage as <empty> will generate this message. However, this does not mean that the results of the column are incorrect, just the hydraulic analysis of the column will not be performed.
To solve this error, simply navigate the flowsheet and locate the Column referenced by the message and switch to the Internals tab, notice that one of the column sections (CS) will have no defined End Stage, simply enter the desired stage to remove the message.
Though not common, this behavior can appear if the user completes the Internals set up of a column and then decides to change the total number of stages in it. Since the total number of stages changes, the previously defined End Stage is removed automatically by Aspen HYSYS to allow the user to verify and re-configure how the Internals Section will be in the new column.
Keywords: Message, Column, Section, Internals, Tray, Packing, Rating
References: None |
Problem Statement: I am getting the error message: Html Report Failed! Item has already been added
How do I resolve this issue? | Solution: This message can happen when there is a configuration issue or corruption of the results.mdb file. Deleting the results.mdb file will usually resolve the issue.
Keywords: None
References: None |
Problem Statement: This | Solution: outlines the procedure for configuring Aspen Mtell to automatically import data from csv files instead of with a live connection to a historian. This implementation methodology is generally used if the historian is far beyond a firewall or if there is a desire to limit the load on the historian.Solution
A “CSV Imported Tags” Plant Historian must first exist in the Aspen Mtell configuration with a defined csv file format. The csv files that are generated must follow the format as specified in the csv historian. For instructions on this, please reviewSolution 46995.
When the csv files are generated, either by a user, or automatically by the plant historian, the csv files need to be transferred to C:\Program Files\AspenTech\Aspen Mtell\Mtell Agent Service\CSV\TagImport. This is a hard-coded path and cannot be configured otherwise. When the Agent Service runs, it will look in this folder for any new csv files to import and move them over to C:\Program Files\AspenTech\Aspen Mtell\Mtell Agent Service\CSV\TagProcessed once the import procedure finishes. It will then be up to the user to remove the csv files from the TagProcessed folder if disk space needs to be preserved.
Keywords: Automatic data import
References: None |
Problem Statement: Can we add persisting breakpoints in VSTA debugging? | Solution: Starting from V10 CP5 you can now add persisting breakpoints. It means that breakpoints placed during the debugging process now persist after closing the VSTA IDE.
Key words
breakpoint, debugging
Keywords: None
References: None |
Problem Statement: In the legacy Titan version, there was an easy way to create multiple scenarios and compare them. Is there a similar feature in V10? | Solution: Although we don't have the option to create multiple scenarios we have added a case comparison feature starting in V10 CP3. The File Inputs Comparison window allows you to compare the inputs of two model files. This allows you to easily determine the differences and unique occurrences between model files without comparing each model's RAM data. Two major benefits of the File Inputs Comparison window are:
1. Determine the causality of changes in results or lack of changes in results.
2. Check if the model has any unwanted input changes.
The File Inputs Comparison window can be accessed by navigating to the Home ribbon in the RAM Data environment.
Key words
File comparison
Keywords: None
References: None |
Problem Statement: In this example, you will evaluate if the current trayed column configuration is hydraulically adequate for base case operation. You will then evaluate the hydraulic and process benefits of installing Raschig packing for the next turnaround. Finally, the increased V-L contacting provided by the new packing will allow you to determine how much incremental OPEX savings can be gained by reducing reboiler duty or decreasing amine flow rate, while still meeting specs.
As the process contact engineer for your gas plant, you were asked to evaluate the operational benefits vs. CAPEX of revamping the absorber column from a trayed design to packing at the next turnaround.
You and your operator are seeing some performance degradation in the acid gas treating unit.
The sales gas product has been approaching the max specs of 4 ppm H2S and 23,000 BTU/lb heating value
With a turnaround approaching in a year, you believe that installing absorber packing would result in more efficient vapor/liquid contacting, improved hydraulics, and increased sales gas quality
You have tuned the existing base case operation using a HYSYS Acid Gas Cleaning model and would like to use simulation to understand the benefit of installing packing in the absorber. | Solution: Use the tuned HYSYS Acid Gas Cleaning model to:
1. See if the existing column is hydraulically limiting
2. Evaluate the effect of installing Raschig packing at the next turnaround on product quality
3. If sales gas quality is predicted to improved, determine if you can reduce the required amount of amine solvent or reboiler duty to save on OPEX and reduce product quality giveaway, while still meeting specs.
You will learn to use HYSYS Acid Gas Cleaning, Column Analysis, and the HYSYS Case Study Utility.
HYSYS Acid Gas Cleaning is a rate-basedSolution that accounts for both mass-transfer and kinetic effects in the absorber and regenerator columns. HYSYS Acid Gas Cleaning property packages support a range of amines and amine blends, heavy hydrocarbons, mercaptains, acid gas components, and other key components. Reaction chemistries are automatically generated and “Efficiency and Advanced Modeling modes are supported for increased accuracy or performance.
Keywords: HYSYS, Acid Gas Cleaning, Column Hydraulics, rate-based modeling, absorber, regenerator, amines, amine blend, MDEA, efficiency mode, advanced modeling mode, heat stable salts, amine treating, acid gas treating, gas plant, gas processing, tail gas treating, hydraulics, flooding, weeping, base case, max rating, turndown, example, reboiler duty, solvent, raschig, packing, trays, column, case study, case study utility, sales gas, sweet gas, rich amine, lean amine, H2S, CO2, HHV
References: None |
Problem Statement: What standard is used by EDR to calculate the shell-to-bundle clearance? | Solution: EDR uses TEMA standards for this purpose. TEMA starts with shell to baffle OD clearance (See Table RCB-4,3), then considers enough to be able to build the bundle and remove the bundle when removable. Typical fabricator clearances tube-OD-to-shell-ID is 1/2 on diameter (1/4 on radius) for fixed tubesheet units and U-tubes. Variable for floating heads to make sure the rear head can be removed.
Keywords: Shell, Bundle, Clearance
References: None |
Problem Statement: Is it possible to model Electrolyte Chemistry and Pseudocomponents? How are binary parameters generated? | Solution: The NRTL and UNIQUAC binary parameters for water and pseudocomponents are intended for use in LLE calculations, as water and hydrocarbons tend to form two liquid phases. These interaction parameters are estimated from the mutual solubility data. The solubility of water is estimated from one of the methods described below. The solubility of pseudocomponent in water is estimated from the API procedure 9A2.17:
To determine the Pseudocomponent formula (ATOMNO/NOATOM parameters), we assume that the pseudocomponent is hydrocarbon consisting of only C and H atoms. We compute the number of C and H atoms from the molecular weight and the Carbon to Hydrogen ration (C/H ratio). (Note that C/H ratio is estimated using procedure in TECHNICAL DATA BOOK - PETROLEUM REFINING, VOL. 2 (FIGURE 2B6.1), AMERICAN PETROLEUM INSTITUTE, 1983.) We further assume that the component is paraffin and adjust the number of carbon atoms to obey CnH2n+2. As a result, H is a whole number, but C may be fractional.
Then we estimate solubility of water in hydrocarbon (from the WATSOL parameters which can be estimated using either the Aspen method, the Kerosene line, or user-supplied method) and solubility of HC in water (API PROCEDURE 9A2.17.)
Since water and hydrocarbons are essentially immiscible, the mutual solubilities are very low. As a result, the solubility is inversely proportional to the infinite dilution activity coefficients. For infinitely dilute binary system, binary interaction parameters for the NRTL and UNIQUAC models can be computed directly from infinite-dilution activity coefficient data.
Now, Aspen Plus does not display all the property parameters on the parameters form, so we need to go the Home Ribbon and select Tools | Retrieve Parameters to be able to check the NRTL/UNIQ parameters. They will be available under Methods | Parameters | Results | Binary Interaction | T-Dependent
Keywords: Pseudocomponent, NRTL, UNIQUAC, Binary Interaction, Estimation.
References: None |
Problem Statement: In the simulation import process of an Aspen Plus file, stream properties of hierarchy blocks are not transferred to Aspen Basic Engineering (ABE). What do I do to transfer this information? | Solution: As explained inSolution Aspen Zyqad Property Set for Aspen Plus, certain stream data may not be transferred to ABE because the necessary properties/property set has not been set up in Aspen Plus.
Setting up a property set should transfer the information to Aspen Basic Engineering, but when we have hierarchy blocks the property sets from the parent flowsheet are not added by default. If you want to transfer also the information of streams in the hierarchy blocks, the property sets should be added also in the hierarchy blocks Setup folder.
Keywords: Property Set, hierarchy block, simulation import, mapping.
References: None |
Problem Statement: How to create a dump file using the Microsoft feature ProcDump ? | Solution: ProcDump is a command line tool for collecting dumps that is freely available from Microsoft. Applications can either be launched with ProcDump (very useful if the application is crashing on startup), or attached to with ProcDump.
Additionally ProcDump can immediately collect a dump in the case of attaching to a process, or be configured to collect a dump when a variety of conditions are met (the application crashes, hangs, uses too much CPU/memory, etc).
According to its owner, Microsoft (Sysinternals), ProcDump includes hung window monitoring (using the same definition of a window hang that Windows and Task Manager use), unhandled exception monitoring and can generate dumps based on the values of system performance counters.
Here are the steps to capture a dump file with ProcDump:
Download ProcDump from https://technet.microsoft.com/en-us/sysinternals/dd996900.aspx
Unzip it to a place (C:\ProcDump, for example).
Bring up a DOS command prompt with “Run As Administrator”.
Navigate to the folder where you unzipped procdump
Launch procdump.exe with the appropriate arguments for your scenario. Below I list a few of the most common arguments, however a full list is available on the ProcDump page):
-e Write a dump when the process encounters an unhandled exception.
-h Write dump if process has a hung window (does not respond to window messages for at least 5 seconds).
-ma Write a dump file with all process memory. The default dump format includes thread and handle information.
-x Launch the specified application
-g Run as a native debugger in a managed process (required for collecting dumps from processes running .NET code)
For Windows 8
For Windows 7
Enter command cd c:\procdump to go the folder. Enter command procdump /h to show the help. A dialog will be shown to ask you to read and accept the license agreement of ProcDump. Click on Agree to close it (You only need to do this once).
Start our application (APS or MBO).
Start the Task Manager to get the PID number. Make sure the PID column is selected.
The figure shows the PID of Orion.exe as 3872. Yours should be a different number, and the number is different next time you run Orion.exe.
Once collected, please share the Dump file with AspenTech support Team for further investigation and analysis.
Other examples of collecting a dump with ProcDump:
Launch an application with ProcDump and collect a dump with heap when the process crashes:
C:\>procdump –e –ma –x -g crash.dmp C:\Dumps “C:\My Applications\CrashingApp.exe”
Attach to an application that is hung and collect a dump with heap immediately:
C:\>procdump –ma HangingApplication.exe hang.dmp
Launch an application with ProcDump and collect a dump with heap when process either crashes or hangs
C:\procdump –e –h –ma -g –x C:\Dumps “C:\My Applications\Application1.exe”
Keywords: None
References: None |
Problem Statement: How to connect Aspen Cloud Connect to Aspen InfoPlus21? | Solution: Aspen Cloud Connect can connect to Aspen InfoPlus21 using the Aspen InfoPlus21 OPC UA server, or the Aspen InfoPlus21 OPC DA server. Here are configuration details for making the connections.
Aspen InfoPlus21 OPC UA server connection:
Setup the certificate trusts following KB “How to configure a UA certificate trust between Aspen Edge Connect and Aspen InfoPlus.21”.
Determine the OPC UA server endpoint;
Use the CimIO Connection Manager, Aspen OPC UA explorer, or another tool that can provide the connection string.
EX: opc.tcp://NODE1:63500/InfoPlus21/OpcUa/Server - [SignAndEncrypt:Basic128Rsa15:Binary].
Open the Aspen Connect Toolkit.
Select the OPC UA tab.
Copy the OPC UA server endpoint string into the OPC UA space and click the Connect button.
Set the User Identity Type to UserName and click OK. Note; Anonymous user identity in not supported by the Aspen InfoPlus21 OPC UA server.
Set the Authentication mode to UserName and enter a username and password and click OK. Note: The user must have access to Aspen InfoPlus21, AspenTech recommends using the Aspen InfoPlus21 system account.
Once the connection is established the left hand pane will be populated with the OPC UA tags tree.
Aspen InfoPlus21 OPC DA server connection:
Open the Aspen connect Toolkit.
Select the OPC Classic tab.
In the Server dialog select <Browse>.
When the Select Server dialog appears select Aspen.InfoPlus21_DA.1 from the list and click OK.
Once the connection is established the left hand pane will be populated with the OPC DA tags tree.
Keywords: Edge Connect
References: None |
Problem Statement: What do the different messages in the message panel mean? | Solution: Starting V10 CP3, the Message Panel now shows relevant information, warnings, and errors associated with the model to help you solve any issues you may come across while working with Aspen Fidelis Reliability. The Message Panel can be accessed by navigating to the View ribbon | Show group | Message Panel in the Simulation environment. There are three types of messages in the Message Panel window: Errors, Warnings, and Information.
Errors: Displays invalid parameter entry which prevents you from running the simulation.
Warnings: Displays connectivity issues in the unit diagram which does not prevent you from running the simulation but may affect your results.
Information: Displays simulation and validation information.
Key words
message panel, error, warning
Keywords: None
References: None |
Problem Statement: This knowledge base article documents the SYNTAX used for OPC UA tag addresses. | Solution: The OPC UA tag name syntax is defined by a OPC UA server in accordance with OPC Foundation standards. Refer to the vendor’s OPC UA server documentation for a description of the valid tag name syntax for that server.
Here is an example of an OPC UA tag name syntax used to retrieve a value from the Aspentech InfoPlus.21 OPC UA Server for tag ATCAI using the Browse Path and NodeID methods. Note: 3ed party OPC UA Clients typically use the NodeID, whereas CimIO for OPC UA uses the Browse Path.
Browse Path:
/Objects/2:DA/2:IP_AnalogDef/2:ATCAI/2:Measurement
NodeID:
ns=2;b=AAAAAAEAAAAeCAAAAABZdMsDAAA=
Keywords: None
References: None |
Problem Statement: How to add the VBA code reference in Excel to Microsoft Visual Basic for Applications Extensibility 5.3?
The screen-shot below shows the current Excel configuration: | Solution: The VBA Extensibililty library contains the definitions of the objects that make up the VBProject. In the VBA editor, go the the Tools menu and choose
Keywords: VBA,
References: s.
In that dialog, scroll down to and check the entry for Microsoft Visual Basic For Applications Extensibility 5.3. If you do not set this reference, you will receive a User-defined type not defined compiler error.
Next, you need to enable programmatic access to the VBA Project.
In Excel 2003 and earlier, go the Tools menu (in Excel, not in the VBA editor), choose Macros and then the Security item. In that dialog, click on the Trusted Publishers tab and check the Trust access to the Visual Basic Project setting.
To add the VBA code reference, please try the following steps:
1. Go to Excel spreadsheet and then press keyboard Alt+ F11
2. A window with the Microsoft Visual Basic for Applications will appear. Then select Tools and click 'References'
3. A window will pops up 'References– VBA Project'
Scroll down in Application References:
You need to have checked the option: ͞Microsoft Visual Basic for Applications Extensibility 5.3
4.Click OKAY and save the Excel sheet.
This will enforce the VBA projects to access the VBA libraries without any errors. |
Problem Statement: How can I change the temperature of the viscosity displayed in the Cold Properties Analysis? | Solution: The viscosity of a stream in the Cold Properties Analysis is reported at two different temperatures 100F (37.8C) and 210F (98.9C).
These temperatures in the Cold Properties Analysis are hard coded and cannot be modified. As a workaround, you can copy the stream, change the temperature to whatever you want and look at the actual viscosity (at the stream conditions) on the Properties section of the stream property view.
Keywords: Viscosity, Cold Properties Analysis, 100F, 210F.
References: None |
Problem Statement: Why Heat Recovery Steam Generator (HRSG) operational status may change after Optimization run? | Solution: When the flowsheet is run in simulation mode, the user can select either “ShutDown” or “InService” option for the operation status of HRSG.
During regular simulation run this is not changed. However, during flowsheet Optimization run, if the optimization solver finds zero flow through this equipment can fulfill the optimization objective function, then it puts the HRSG in ShutDown mode. As a result, all the equations related to HRSG are excluded from model calculations and all relevant variables are changed to Fixed status. This makes sure that irrespective of HRSG run status, flowsheet is square.
Key Words
HRSG, Optimization, ShutDown, InService
Keywords: None
References: None |
Problem Statement: How to configure Aspen cloud connect to publish data to an OSISoft PI Historian. | Solution: Requirements:
PI Web API Version 2015 R3
Access to OSISoft PI System Explorer Application
Permissions to Edit PI-AF database
PI User Account with Permissions to Create Tags and to Write Data to Tags
Access to the Aspen Connect Toolkit
Step 1: Access the PI Web API configuration
First access the PI AF Server and AF Configuration database that holds the OSISoft’s PI Web API configuration.
Step 2: Set the Authentication Method for the PI Web API to Basic
Open the AF database called Configuration that holds the OSISoft’s PI Web API configuration.
Expand the Elements and navigate as shown below. Elements-> OSISoft-> PI Web API -> Main Server Name -> System Configuration.
Select the Appropriate branch then Edit the attribute in the middle panel that says AuthenticationMethods.
Double click or select the drop-down arrow to edit. In the popup edit window hit the add Button, then rename the Top value “Kerberos” next to the item 0 to “Basic” as shown below.
Hit OK.
Step 3: Restart the PI Web API for the Basic Setting to be activated
Open the Windows Services Panel and Restart the 2 PI Web API Services as shown Below.
Restart: PI Web API 2015 R3 and PI Web API 2015 R3 Crawler
Step 4: Ensure we have the correct name of the data server for the PI Web API Server
Open a web browser and navigate to the PI Web API Data Servers page as illustrated below.
Browse to https://XXXXXX/piwebapi/dataservers
Note the “Name”: “XXXXXXXXX”, parameter for the Aspen Connect Settings.
Step 5: Configure Aspen Connect for the PI Web API Server
Open a web browser and navigate to the PI Web API Data Servers page as illustrated below.
Ensure that the noted Data Server Name is correct from previous step.
Step 6: Restart the Aspen Connect services just to be sure!
Open the Windows Services Panel and Restart the 3 Aspen Connect Services as shown Below.
Aspen Edge Connect, Aspen Edge Connect BackLog, and Aspen Edge Connect Local Calc Engine
Keywords: None
References: None |
Problem Statement: How can I copy a parameter from one stream to another such that it updates automatically? | Solution: This can be easily accomplished using a Set operation.
If for example you wanted to copy the temperature from stream 1 to stream 2, you would set the Target variable to be Stream 2, temperature and the source object to be stream 1.
To copy the value exactly set the multiplier to be 1 and the offset to be 0, on the Parameters tab.
Keywords: Set, Copy Parameters.
References: None |
Problem Statement: Why is my RPLUG reactor calculating a conversion higher that 1.0 and how can I avoid it? | Solution: Depending on the conditions and the kinetics of a reaction in an RPLUG model, in some occasions a very high conversion can be calculated by Aspen Plus.
When these high conversions (near 100%) are expected, it is possible that due to the convergence algorithm of the RPLUG block, the user can find a molar flow of the product(s) higher than the reactant(s), indicating that a conversion higher than 1.0 has resulted.
This is simply caused by the algorithm that the RPLUG block uses to calculate the component flows and report them back into the Aspen Plus stream results. To prevent this behavior, open the RPLUG block and go to Convergence | Integration Loop, then activate the option “Integrator forces flowrates to have positive values”, this option will change the convergence algorithm to prevent obtaining higher product molar flows that what was specified in the reactants.
Keywords: Conversion, PFR, Oversize, Higher, Unrealistic, Reactor
References: None |
Problem Statement: How to open and link Aspen Utilities Planner file from Excel Add-In? | Solution: Please follow the steps below to link Aspen Utilities Planner with Excel Add-in:
Open the Aspen Utilities planner file first.
From the Aspen Utilities Add-In menu, select Open Aspen Utilities
3. Point to the model location and select Open.
4. When prompted with the following question, press Cancel
The Excel file and the Aspen Utilities model are now linked.
5. Select Show Aspen Utilities, to make the model visible
6. The Aspen Utilities icon should appear, the model is now linked and visible
Key Words
Add-In, Active, Utilities Planner
Keywords: None
References: None |
Problem Statement: Connection stream type is very commonly used to connect blocks in an Aspen Custom Modeler flowsheet. This stream type does not have any variables and it simply links variables between the ports that it is attached to. This is shown by the < and > signs before the variable name in the stream table, which indicate where the stream is taking the variable from. This will usually be from the port of the block where the stream was connected to.
So how can the variables from a stream using the Connection stream type be accessed within a script? | Solution: To access these stream variables within a script there are two options:
The simplest option will be to use the port variable from the block directly, i.e.:
BlockName.PortName.VariableName.value = number
Another option is to find out where the stream is connected and refer to it. This is useful if, for some reason, the user still needs to refer to the stream name as it may be connected to different blocks in different instances. The example attached to this article illustrates how this is done.
The example contains a script called test in the Flowsheet, which contains the following code.
' Changing the value for the feed flow
if Streams(FeedStream).OutputConnected then
set p = Streams(FeedStream).OutputBlockPort
p.Flow.value = 4
else
application.msg Not a feed stream
end if
' Changing the value for the product flow - only for illustration as this Flow
' is not fixed in the flowsheet
if Streams(IS5).InputConnected then
set p = Streams(IS5).InputBlockPort
p.Flow.value = 4
else
application.msg Not a product stream
end if
Normally you would want to use the script to change the value of a fixed variable in the stream. In our example the second part referring to the change to be made on the product stream IS5 is for illustration only, since the Flow variable is not fixed. The script is checking whether the stream named has its output connected (for the feed case) and then changing the value for the variable in the port where it is connected to. The same applies to the second part where the value for the product flow is changed.
Invoke script test and see the values changing for the respective variables on the tables.
Keywords: script, connection, stream
References: None |
Problem Statement: WARN> 'PIP- #' NO DEFAULT COMPONENT INSULATION AVAILABLE, PLEASE PROVIDE COMPLETE SPECIFICATIONS
What does this warning mean and how does it affect my results in Aspen In-Plant Cost Estimator? | Solution: The warning above can show up in Aspen In-Plant Cost Estimator when the user loads a Custom Pipe Specs file into the estimation project and then adds piping items with no Insulation Thickness specified.
This warning simply indicates that there is no insulation thickness specified for the specific piping items, therefore, Aspen In-Plant Cost Estimator will not add insulation to this item.
If the user does not intend for the program to generate insulation for the pipes presenting the warning, then the message can be ignored, as the program will not generate any extra cost. If on the other hand, the user does want to take into account the insulation cost for this item then it's necessary to manually specify the Insulation Thickness (and material if desired).
Keywords: Piping, Insulation, Warning, Results, Custom, Scan.
References: None |
Problem Statement: How do I report the compressibility factor (Z) for the vapor in a specific tray in a distillation column? | Solution: Some property data, such as transfer properties, temperature and pressure in each column stage, can be reported in Aspen HYSYS under the Performance | Plots section of the Column window.
However, not all the stream properties can be reported on this summary, such is the case of Z factor. The values of these properties need to be manually obtained from an internal (virtual) stream in the column environment.
On the Column window, navigate to the Flowsheet tab and select Internal Streams. To create one or more internal streams, the user needs to provide a name to the stream(s) (i.e. Tray 4 Vap), then select which tray should this stream copy and select Vapour as the Type. Repeat this for all the trays you are interested on looking.
Note: Vapour is selected in this article since it is focused on obtaining the Z Factor.
Once created, the user may review the new stream(s) inside the column environment.
By opening the stream and looking at the Properties summary of this, the user can add Z Factor to be displayed.
Optionally, the may check the Export option under Internal Streams to display this virtual stream into the main environment, which will avoid the user from manually adding Z Factor to the stream properties.
Keywords: Z Factor, properties, column, tray, virtual, internal
References: None |
Problem Statement: The simulations that I build are generally complex with multiple Events/Units. Is there a way to find an element without having to navigate through the entire flowsheet? | Solution: Starting with V10 CP3, the Find Element window allows you to easily find any element by name in the flow diagram or unit diagram without searching in the simulation environment. The major benefit of the Find Element window is the ability to locate the unit diagram where events reside. The Find Element window can be accessed by navigating to the View ribbon | Show group | Find Element button in the Simulation environment. The Find Element window allows you to perform a string search for all element's name parameter. You can also access the Find Element window by clicking Ctrl-F.
Key words
find element
Keywords: None
References: None |
Problem Statement: What are the distillation curve types supported in HYSYS Petroleum Assay? | Solution: In Aspen HYSYS, th user can manually enter petroleum data to define a Petroleum Assay and its properties. By default, when the user creates a new Petroleum Assay, Aspen HYSYS will provide the option to enter TBP data.
If the user wishes instead to enter a different type of distillation data, select the Single Stream Properties option and change the distillation type to the required type
The available distillation data type are TBP, D86, D1160 and D2887.
Keywords: RefSys, Assay, Multi Cut Properties, Distillation, Cuts
References: None |
Problem Statement: Fugacity - Can I access it for my stream? | Solution: No, even though this property is computed in the flash calculation, the HYSYS internal structures do not cache this information. Therefore, the fugacities for a stream or individual phases are not user-accessible in HYSYS, unfortunately.
Keywords: Fugacity, Properties.
References: None |
Problem Statement: How to ramp the controller set point over a fixed duration of time in Aspen Plus Dynamics | Solution: You cannot directly ramp SP value because SP is a state variable. You can only step change the value of SP. If you want to ramp the controller set point, first set the controller to Cascade mode, and then ramp the remote set point (SPRemote) from a form or a task.
(1). If you want to ramp from a form, right click on the SPRemote in the AllVariables Table and click “Ramp”. In the Variable Ramp dialogue box, define the final value and duration.
(2). You can also create a task in the flowsheet. Here is an example:
TASK TaskName RUNS AT time
Ramp (PC.SPRemote, final_value, duration);
END
Keywords: Set Point
Ramp
Controller
Task
References: None |
Problem Statement: How do I simulate a vent line attached to a depressuring vessel? | Solution: The Depressuring Utility does not allow the addition of unit operations. However, if you need to simulate a vent line, a dynamic simulation can be built in order to accomplish this. Figure 1 shows a flowsheet that can be implemented in Aspen HYSYS Dynamics in order to simulate a depressuring system with a vent line.
Figure 1. Depressuring system with a vent line.
Figure 1 shows a vent line that can be modeled with a Hydraulics pipe segment and a detailed heat loss model can be used to determine the vent line wall temperature profile.
The following has to be considered when building and adjusting the dynamic starter file:
1.- VLV-100 should have a Cv value big enough to have a very low pressure drop.
2.- A level controller can be added if an initial liquid level is required in the Vessel.
3.- A detailed heat loss model for the Vessel can be specified (Vessel view | Rating | Heat Loss).
4.- If a fire model is required, a spreadsheet and an energy stream could be added (seeSolution How do I make the best use of the Aspen HYSYS Dynamic Depressuring Utility?).
5.- Consider the tips mentioned inSolution Tips on modeling the depressurization of a filled vessel using the Dynamic Depressuring utility..
In order to simulate a depressuring process the following steps have to be taken:
1.- Open valves VLV-100 and VLV-101 (100% Valve Opening).
2.- Close valves VLV-102 and VLV-103 (0% Valve Opening).
3.- Run the Integrator until all conditions are stable and constant.
4.- Stop the integrator.
5.- Close valves VLV-100 and VLV-101 (0% Valve Opening).
6.- Open valve VLV-102 (100 % Valve Opening).
7.- Run the integrator.
TheSolution simulation case, built in Aspen HYSYS V8.8, has a dynamic simulation illustrating the implementation of the depressuring flowsheet shown in Figure 1.
Keywords: Blowdown, flare line, shutdown, emergency, trip
References: None |
Problem Statement: The error “CIMIO_DAL_GETDEVICE_NOSERVICE” may appear in the CimIO_MSG.log if the interface startup is not able to get the logical device name for the scanner, store and forward processes | Solution: The message can be resolved by creating a logical device entry for the interface in the CimIO_Logical_Devices.Def file.
Run the CimIO_T_API.exe
Select option 2 Test Adding a Logical Device
Follow the prompts to enter the details of the interface device
Restart the interface
Keywords: No service
Cim_io
References: None |
Problem Statement: Is it possible to connect Aspen Custom Modeler (ACM) and Python? | Solution: Calling Python from ACM: ACM supports Procedures which are auto-generated fortran or C wrappers that the solver can call directly. If the user compiles his/her Python with Cython, it will generate C code that can be called from a C procedure in ACM. For numerical stability, it is recommended that users return analytic derivatives, especially if they have a large number of inputs and/or outputs. If this is not possible, ACM will perform perturbations to approximate them.
Calling ACM from Python: There are some differences in how pywin32 COM libraries do their string marshalling compared to C# and VB so there are certain methods that may not work correctly from pywin32. Comtypes could present a similar behavior.
Keywords: ACM, Custom Modeler, python
References: None |
Problem Statement: How can I adjust the mole fraction of a component in a stream? | Solution: Sometimes it is desired to either have the freedom to adjust a component mole fraction using an Adjust or in a Case Study. It is not possible to do this directly from the stream, but there is a way to accomplish this using a pure component stream and a mixer.
Create a stream with the composition specified to contain only the pure component whose mole fraction you would like to vary. Blend it with the remainder of your feed stream using a mixer. Now you can adjust the molar flow rate of the pure component stream until you reach a desired mole fraction for that component.
Another option is the use of the Spreadsheet operation, a sample with this procedure can be found here How do I vary the composition of a stream in a case study?
Keywords: Adjust, Case Study, Mole Fraction, Stream.
References: None |
Problem Statement: How are hypothetical components generated by the Oil Manager named? | Solution: Hypothetical components generated by the Oil Characterisation function in HYSYS are named as follows:
NBP[x]y
(E.g. NBP[0]28)
x is just a marker to indicate which oil blend the hypo belongs to. For example if in the Oil Characterisation Environment you set up two blends then the hypos belonging to the first blend will be called NBP[0] and the second NBP[1]. Each blend has its own set of hypos, they are not shared between blends.
y is the Normal Boiling Point (NBP) of the hypo. The units for y are those in use in HYSYS when the hypos are created. Hypo component names do not change if the units in use in HYSYS subsequently change. The only time they do change is if the hypos are regenerated (e.g. when you change one of the assays that goes to make up the blend).
Keywords: Oil Manager, Hypothetical Component Name, NBP, Normal Boiling Point.
References: None |
Problem Statement: Heat Transfer Fluids and Refrigerants. What do the names mean? | Solution: Attached is an Excel spreadsheet with the following:
A list of the Refrigerants and their full names, including the composition of the refrigerant (where known).
A list of the heat transfer fluids with their HYSYS abbreviation, full name, manufacturer and some public domain information about their composition.
Keywords: Refrigerant, Thermal Fluid, Heat Transfer Fluid
References: None |
Problem Statement: How can I copy stream information and have the second stream update every time the first stream flashes? | Solution: Use a Balance to pass along the molar flow rate, composition, and the enthalpy/heat flow (set the balance type to Mole and Heat). Add a Set operation to specify the pressure. The stream will now have enough information to force a flash.
Other option is the use of the Virtual Stream operation. Add it and connect to the desired streams. Then select the information you would like to transfer between both streams.
Keywords: Copy Stream Specs, Automatically Update, Balance, Virtual Stream.
References: None |
Problem Statement: What is the Hydraulic Plot? How do we view and interpret the plot in Aspen HYSYS Column Internals? | Solution: The Hydraulic Plot is used for studying the tray/packing hydraulics of the column sections in Aspen HYSYS. It is a vapor vs liquid (mass) flow rates plot showing the stable operation region.
The Hydraulic Plots form is divided into these main sections: The column diagram appears on the upper left. Below it, when a tray is selected, the downcomer loading and weir loading diagrams appear. The large plot on the right is the stability diagram. Below it is the carousel, which shows a small version of the stability diagram for each of several stages.
To access the hydraulic plots, any of the following options can be used:
On the Internals tab of the Column property view, click the View Hydraulic Plots button. or
On the Internals form, click the View Hydraulic Plots button. or
On the Geometry form, click the View Hydraulic Plots button.
For Trayed Hydraulic Plots Boundaries considered are Weeping, Jet Flood,Downcomer Backup,Maximum Entrainment, Weir Loading,Maximum Capacity, and Maximum dP.
For Packing Hydraulic Plots Boundaries considered are Ultimate Capacity,Minimum Liquid Rate,Minimum/Maximum Pressure Drop
When the operating point is within the limits of the boundaries, it is a stable hydraulics region.
Keywords: Column Internals, Hydraulic Plot, Tray, packing
References: None |
Problem Statement: What does Auto Calculation check box do in the Equilibrium Plots operation? | Solution: Its purpose is to have the plot automatically update itself when an input changes (e.g. temperature, pressure, and component).
When the Auto Calculations check box is unchecked, changing an input causes the plot to clear and Plot must be pressed to re-draw the plot. With Auto Calculations on, the plot updates itself on input changing.
Keywords: Equilibrium Unit, extension
References: None |
Problem Statement: What is the break point between small bore vs large bore in the ACCE Excel Above Ground Piping Analysis report? | Solution: The ACCE Excel report AG (above ground) Piping Analysis includes a summary displaying the characteristics of the piping added to the project, such as average diameter, number of welds, total length, etc.
In this report, some information is divided in large bore and small bore to better represent the data. The division that separates small from large bores is the pipe diameter, which at a value of 2 inches and lower will be classified as small bore.
Any pipes with a diameter higher than 2 in will be classified and reported as large bore.
Keywords: AG, Piping, Excel report, division, break point, large bore, small bore
References: None |
Problem Statement: I would like to run a schedule and to be able to start or stop a sequence that exists in another schedule. Is this possible? | Solution: In Aspen HYSYS Dynamics, the ‘Event Scheduler’ allows users to set up both customized and complicated scenarios to perform given tasks at predetermined times once a simulation is running in dynamic mode.
The Event Scheduler window contains all the ‘Event Schedules’. Each ‘Schedule’ is comprised of ‘Sequences’, which in turn are made up of ‘Events’. An Event must have a ‘Condition’ (a null condition is always true)
It is important to note that there is no way to execute a sequence from a different schedule. The only thing that can be done is to export a sequence from one schedule and import it (as a *.seq file) into another. The export / import options are in the ‘Schedule of Events’ form.
To get to know more about the Event Scheduler in Aspen HYSYS Dynamics, users may consult the Help Guide in Aspen HYSYS, as well as the following KB Articles:
1) Application example of the Event Scheduler
2) Event Scheduler Demonstration Model
Keywords: Event Scheduler, Schedule, Sequence, Event, Import, Export, Dynamic Modeling.
References: None |
Problem Statement: Are all scenarios available in the PSV Safety Analysis able to calculate the Relieving Flow? | Solution: No, this feature is only applicable for some scenarios (see below):
· Fire
· Control Valve Failure
· Exchange Tube Rupture
· Fan Failure
· Reflux Failure
· Thermal Expanison
For these scenarios, a specific relief load calculation is prescribed by Aspen HYSYS and a calculated value will be given by providing more parameters surrounding the scenario when prompted (such as vessel information). If you have obtained the relief load from another source, you can type this value in the specified relieving flow field.
1. Fire scenario:
In the Fire scenario physical properties routines have been provided to execute analysis of a multi-component mixture during fire and to calculate required orifice in a two-phase scenario in accordance with the direct integration method. The Safety Analysis environment eliminates the need to perform any fire load related calculation. The method used is from the API 521 latest edition. The options available will calculate fire loads for both Wetted and Unwetted vessel surface cases. The calculated fire load depends on the selected vessel's geometry, dimensions, elevation and fluid latent heat. The load calculations for fire are applicable only to vapor and steam phase models.
2. Control Valve Failures scenario:
Control valve failure occurs when the control valve becomes fully open. When a control valve fails in the fully open position, the downstream side process must be considered for protection with a PSV because it may not be designed to handle the additional flow. A detailed calculation form is available to rigorously calculate the consequences of the complete opening of a control valve. Calculation routines take into account control valve CV calculation, if not already available, and cover a gas break-through situation, which is one of the most frequent scenarios encountered. The load calculations for control valve failure are applicable to vapor, steam, liquid, mixed A/B/C, and direct phase models
3. Exchange Tube Rupture scenario:
Many heat exchangers have a significant pressure difference between the tube and shell side. Failure of one or more tubes causes a high flowrate into the low pressure side. The Exchanger Tube Rupture scenario lets you calculate the relieving rate consequent to a breakage in one of the tubes of the heat exchanger. Determination of relieving load for this case is accomplished using complex calculation routines. The load calculations for exchanger tube rupture are applicable to vapor, steam, liquid, mixed A/B/C, and direct phase models.
4. Fan Failure Scenario:
In case of failure of one or more fans, the loss of cooling or condensing may lead to pressure increase in the system and subsequent opening of the PSV. The load calculations for fan failure are applicable only to vapor and steam phase models
5. Reflux Failure Scenario:
The reasons for reflux failure include improper operation of isolation valves, reflux pump failure, and failure of the control valve. Reflux failure results in the accumulation of more liquid in the reflux drum, which will eventually flood the drum and overhead condenser and result in loss of cooling. The column pressure will increase and the PSV will lift. Failure of a column top or side reflux causes pressure increase in the system as higher vapor rate than normal will be present in the column. The load calculations for fire are applicable only to vapor phase models.
6. Thermal Expansion:
Thermal expansion is a major safety concern for the piping system. For a liquid-filled situation, thermal expansion should be considered for the protection of the piping system. If a liquid filled portion of piping or equipment is blocked in under solar radiation, steam or electrical tracing, jacketing, or any other heat source, this will cause pressurization due to specific volume change of the liquid. Calculation of the relieving rate can be easily calculated in the Safety Analysis environment. The method used is from the API 521 latest edition. The load calculations for thermal expansion are applicable only to liquid phase models.
Keywords: PSV, relieving flow calculation
References: None |
Problem Statement: How to view results of the sulfur recovery process using Sulsim in Aspen HYSYS? | Solution: The Performance Summary form is used to view the results of the sulfur recovery process.
User can access the Performance Summary form:
From the Sulfur Recovery Results ribbon tab, click the Performance Summary button.
Or from the Sulfur Recovery Unit Sub-Flowsheet, click the Performance tab
After the Sulfur Recovery Unit (SRU) flowsheet solves and has been divided into different sulfur recovery trains and thermal and catalytic stages within those trains, the performance summary shows various production and efficiency values for the trains and stages.
Keywords: Sulsim, Performance Summary
References: None |
Problem Statement: APC online and AspenWatch servers may encounter problems if the system locale is set to any other than English (United States) | Solution: Since there is no localization done for the APC online and AspenWatch software, the system may encounter problems when the system locale settings for such server is set to anything else other than English (United States).
To avoid run time errors, it is recommended to set the system locale for APC online and AspenWatch servers to English (United States). Make sure to click on the Copy Settings button after making the change. The Prodution Control Web Server is localized so it can set it to any of the supported languages.
Keywords: system locale
References: None |
Problem Statement: How are the Cavett Heat of Vap Coefficients used in the enthalpy calculations? | Solution: On the Point tab page of component view in the Properties Environment, there are two coefficients called Cavett Heat of Vap Coeff A and B.
How HYSYS uses these parameters depends on which property package you are using. For equations of state (EOS) models, like PR and SRK, it is not used at all. With EOS packages the liquid enthalpy is determined using the EOS directly. The latent heat of vaporization reported in each stream is calculated based on the difference between saturated liquid enthalpy and saturated vapor enthalpy at constant pressure.
For activity model property packages (Wilson, UNIFAC, etc.), the Cavett parameter is determined using an iterative method where the coefficients are hard coded into the program. The optimum Cavett parameter is found using the iterative procedure to optimize the heat of vaporization at the normal boiling point (NBP).
The Cavett method in HYSYS is a single term representation, as such it is difficult to match experimental data closely over a large temperature range. The interface displays both Cavett A and B terms but only one (Cavett A) is used in the program. Typically, the predicted data will match exactly at one point (the NBP) but the divergence increases as you move away from this point. Using the Tabular option in HYSYS rather than attempting to change the Cavett A parameter to match Heat of Vaporization experimental data is recommended.
Keywords: Heat of Vaporization, Cavett Parameter, Enthalpy Calculation.
References: None |
Problem Statement: How do I make the best use of the Aspen HYSYS Dynamic Depressuring Utility? | Solution: Connections Page
Enter the vessel dimensions such as Height, Diameter and Head Areas. These parameters are relevant for the heat transfer calculations or the heat load and wetted surface area calculations. Note that for Horizontal vessels the Height is the length of the vessel.
Note that Aspen HYSYS does not take in account extra volumes like inlet/outlet piping segments and head volume contributions. To account for that add a small amount of height or diameter.
When using the Detailed Heat loss model (Heat Flux page) Aspen HYSYS will compute the metal mass of a cylinder plus the one associated with the heads. The default head geometry is a flat disk. So you will need to modify the head area in order to take in account the actual geometry. If you are using the detailed heat loss model, it is recommended to always assume that the metal mass and surface area is relevant. This parameter doesn't affect the simple heat loss model.
When using the Detailed Heat loss model (Heat Flux page) If you have an extra metal mass in contact with the vapour or the liquid (for an example demister, baffle etc) then you should include that in the calculations. To add them enter the metal mass (in kg or lb, not in percent of the vessel mass) under Correction Factors (Metal Mass in Contact with Vapour/Liquid). This parameter doesn't affect the simple heat loss model results.
Strip Charts (Config. Strip Charts Ribbon)
The default Strip Chart is already configured correctly and the refresh rate is the same as the time step. However if you create a new chart you need to manually configure this and update interval so that the fast depressuring dynamics can be recorded accurately. Refer toSolution 125121 for more details on how to configure a chart.
Operating Mode (Heat Transfer Ribbon)
Applied Duty: Models heat from a fire using a general equation and can be used to simulate plant emergency conditions that would occur during a plant fire. Pressure, temperature, and flow profiles are calculated for the application of an external heat source to a vessel, piping, or combination of items.
Adiabatic Set the Heat Loss model to Detailed, since heat transfer with the environment has a significant effect in the adiabatic depressuring studies. The Recycle efficiencies should be in the region of 1% for the gas phase and the PV term set in proximity of 100%.
Fire - API521: When using this correlation remember to set the heat loss model to none and do NOT apply the heat duty to the external surface. This is because this correlation was developed without taking into account the vessel mass and conductivity. Adding a heat loss model to this scenario would cause underprediction of the required relief loads.
Fire - Stefan Boltzmann: This models heat transfer from a fire using a radiation equation. In order to use this in a realistic way you need to specify a detailed heat loss model only and apply the heat load to the external surface.
Use Spreadsheet: This is an option that allows you access to the spreadsheet used by the depressuring analysis tool to customize the equation used. When the Use Spreadsheet operating mode is selected, the View Spreadsheet button appears. Clicking the View Spreadsheet button opens the duty spreadsheet. Values can be altered in this spreadsheet and additional equations substituted for calculation of the heat flux.
Heat Loss Model (Heat Transfer Ribbon)
The Simple model considers the environment but disregards the vessel metal.
The detailed model considers both the environment and the vessel metal. Make sure that the vessel dimensions (diameter, length, thickness, head area) are accurate and to include any extra metal mass data (see connections page).
The detailed heat loss model allows you specify recycle efficiencies for each phase. The Recycle Efficiency is the amount of each phase that is involved in the flash calculation. The default value is 100%, this means that all the material will be flashed together and will be in thermodynamic equilibrium. By reducing the Recycle Efficiency a part of the material will bypass the equilibrium and the liquid/vapour will no longer reach instantaneous equilibrium. For Adiabatic depressuring studies a value of 1% for the gas phase has been found to yield better results for most cases. For fire scenarios leave the efficiencies to its default value (100%).
Valve Parameters Ribbon
Preferably use the Relief Valve or the Fisher. These valves models can compute critical and choked flow conditions.
PV Work Term Contribution (Options Ribbon)
This term refers to the isentropic efficiency of the process. This parameter was introduced to match the conditions observed (i.e: it's a correction factor in front of the PV term of the energy balance). For more details on the PV Work Term Contribution definition refer toSolution 113038.
This parameter affects only the adiabatic depressuring studies and it should be close to the neighborhood of 100%. From a thermodynamic point of view it should be 100%, assuming that you have taken into account all the metal and insulation heat capacities this should give better results. Also the higher the value the lower the temperature in the vessel will be during the blowdown. The PV Work Term contribution is less important for fire case scenarios, so this parameter won't have a significant effect.
Solver settings (Operating Conditions Ribbon)
The step time should be low enough so that the end results do not depend on the step size taken. Also a smaller step time will allow capturing the peak flow. This can be set at the Operating Conditions page.
Starting from Aspen HYSYS V7.0 the execution rates are automatically set to 1 when the utility is running.
Keywords: Depressurization, blowdown, fire
References: None |
Problem Statement: Does Aspen Chromatography predict isotherms for any solute/solvent/adsorbent systems? How could I determine the isotherm model parameters? | Solution: Aspen Chromatography cannot automatically predict the isotherms for your system. You will need to pick the right isotherm for your system based on your engineering judgement. Make sure the isotherm model is appropriate for the process you are investigating. The equilibrium specified by the isotherm model affects the driving force for mass transfer. Consequently, you can get significantly different simulation results when using different models, even if the model parameters are derived from the same set of data.
You could find the isotherm model parameters either by literature research or experimental data fitting. To do the regression, you need to change the run mode to Estimation mode.
For more details, you should read Run an Estimation Simulation topic in the Help menu.
Keywords: Isotherms
Model Parameters
Estimation mode
References: None |
Problem Statement: How to simulate urea in aqueous | Solution: ? I always get an error message saying Calculation stopped because property parameters are missing.
Solution
1. Add your components in the component list, then use Elec Wizard to generate real components and reactions in the electrolyte system.
2. Click Next. Deselect Salt formation and tick Water dissociation as your stream consists mostly of water.
3. Click Next all the way down. This will add the ionic components to your component list.
4. In the Enterprise Database, choose APV100 HYSYS to the selected databanks. The number after APV could be different for different versions of Aspen Plus. In version 9, you should choose APV90 HYSYS. The PLXANT parameters for urea will be retrieved from this database for vapor pressure calculation. PLXANT parameter for urea is not available in any other databanks.
5. Then you can proceed to the simulation environment to build your flowsheet.
Keywords: Urea
Elec Wizard
Enterprise Database
APV 100 HYSYS
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: How is the catalyst heat capacity taken into account in the energy balance of the dynamic Plug Flow Reactor? | Solution: When a catalyst is available in the plug flow reactor, there are three options for the thermal inertia of the catalyst to be incorporated into the dynamic reactor.
1. No heat transfer (default) and no additional input is required. In this case there is no catalyst present, or the effect of heat transfer between catalyst and process fluid on the reactor dynamics is ignored.
2. Heat transfer at equal temperatures. There is very fast heat transfer between the catalyst and process fluid, and they are assumed to be always at the same temperature. Dynamic energy balance of the catalyst is determined by specifying the catalyst's voidage fraction, heat capacity and the mass density.
3. Heat transfer at different temperatures. This is the most rigorous option. Heat transfer between the catalyst and process fluid is determined by their temperature differential, contact area, and overall heat transfer coefficient. Specifications required are the catalyst voidage fraction, heat capacity, mass density, specific surface area and the overall heat transfer coefficient. The governing equation can be summarized as follows:
Rho_cat*Cp_cat*(dT_cat)/dt = U_cat*A_cat*(1.0-Voidage)*(T_gas - T_cat)
Keywords: Catalyst, Plug Flow Reactor, Energy Balance, Aspen Plus Dynamics
References: None |
Problem Statement: I ran my RadFrac column with Column Internals set up to consider my model as a packed section for a rating run. The flowrates in the column are very low. However, the ‘Error in packing section calculations’ message is read under Results. What can be the root cause of this error? | Solution: For some RadFrac columns that have the Column Internals - Rating feature set up to consider the column as a packed column to carry out hydraulic calculations, if the flowrates in the column are too low and the column diameter entered as input by the user turns out to be too large for such small flowrates, then not all the hydraulic calculations for rating sections will be performed, and in the Column Internals | Section | Results | Messages form there will be an error reading Error in packing section calculations.
There will be no other warnings or errors indicated elsewhere (e.g. Control Panel) and the column will seem to solve normally unless you go to the Column Internals | Sections | Design Parameters form and reduce the ‘Minimum liquid flow rate per unit area’ value to an adequately small one, then there will be hydraulic results with specific errors.
The error is caused by small flowrates in the column. The Column Internals feature is intended for commercial columns, not tiny experimental columns. If the flowrates are too small, the hydraulic correlations used in the rating mode are not applicable anymore.
A means of verifying that the manually input value for the column diameter is consistent with the column flowrates order of magnitude is to clear the column diameter field and change the run mode from ‘Rating’ to ‘Interactive sizing’. The calculated diameter should be close to the one that was previously entered by the user and there will be no errors.
Keywords: RadFrac, Column Internals, Packed Section, Rating Mode, Column Section, Interactive Sizing Mode, ColumnDiameter, Flowrate.
References: None |
Problem Statement: Why HYSYS Peng-Robinson property package from “HYSYS” and “Aspen Properties” package types generate different simulation result? | Solution: In Aspen HYSYS, when adding fluid packages, you can choose from “HYSYS” (which is the default option) or “Aspen Properties”.
“Aspen Properties” has more fluid packages for choice compared to “HYSYS”, but both package types contain the most widely used packages like Peng-Robinson:
However, if you are using HYSYS Peng-Robinson from “HYSYS” and “Aspen Properties” for the same flowsheet, you may get different simulation results. The reason is that the two packages set different default valid phases.
When using HYSYS Peng-Robinson from “HYSYS” package type, the default maximum phases allowed is 3.
However, when using HYSYS Peng-Robinson from “Aspen Properties” package type, the default valid phases are vapor-liquid. This could cause some problems if you have a second liquid phase.
If you have water and hydrocarbon (or any other nonsoluable organic species) in your simulation, you need a 3rd (aqueous) phase. You could manually change the valid phases to vapor-liquid-liquid or vapor-liquid-freewater.
Keywords: Aspen Properties
Peng-Robinson
Valid phases
References: None |
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