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Problem Statement: In addition to the ABML (Aspen Blending Model Library) blending methods available in Aspen Refinery Multi-Blend Optimizer, UBML (User Blend Model Library) provides the ability to incorporate user-defined blending correlations into the model.
How do you set up UBML for Aspen Refinery Multi-Blend Optimizer? | Solution: The user defined UBML blending methods are stored in a file created by the user called UBML.dll. This file has to be pasted into the Aspen Refinery Multi-Blend Optimizer installation folder, which by default is:
C:\Program Files\AspenTech\Aspen Refinery Multi-Blend Optimizer
In the sample models folder there is also a folder the necessary files to create the UBML.dll file.
In default installations, for Aspen Refinery Multi-Blend Optimizer 2006.5 and higher, they can be located under this folder:
C:\Documents and Settings\All Users\Documents\AspenTech\Aspen Refinery Multi-Blend Optimizer\Access\Ubml files
Note: Experience programming with C++ is required to create this UBML.dll file.
Keywords: UBML
ABML
PUBML.dll
References: None |
Problem Statement: Why is RadFrac offering the option to enter the Reflux Ratio on a Mass, Mole or StdVol base? Shouldn''t a ratio and as such be independent on the basis. And what is StdVol anyway? | Solution: First of all, the StdVol is an option specifically designed for Refinery and Petroleum applications where it is customary to specify the flow as if all components were liquid at 60 F and 15 psi using standard conventional densities defined by the API (American Petroleum Institute). More on that in: http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=3471 This option will not be investigated in this document, although the findings are analogous to switching from mole to mass basis.
The Reflux Ratio (RR) is the ratio between the top product flow and the liquid flow returned to the column. If the composition of those two steams is the same, then indeed the reflux ratio is basis independent. But if the composition of the top product differs from that of the liquid returned to the column, that is not the case. Their average molar weights will be different and the RR specification then has a different meaning on a mass or mole basis: MASS-RR = MASS-L1/MASS-D = (MOLE-L1*MW-REFLUX)/(MOLE-D*MW-DIST)
This situation can occur if:
The condenser is not total or
There is a decanter on top of the column
The attached example files show three different cases.
The file RR1.BKP has a total condenser and a liquid product. Varying the basis for the reflux ratio from mole to mass does not change the condenser heat duty (stays at -4.6553577 Gcal/hr). Note the tolerances have been tightened resp. the default values on:
RadFrac->Convergence->Basic and on
Setup->Simulation Options->Flash Convergence->Error Tolerance
The file RR2.BKP has a partial-vapor condenser and hence a vapor product. Varying the basis for the reflux ratio from mole to mass changes the condenser heat duty from -0.7609709 to -0.8735618 Gcal/hr. The reason is that the composition of the distillate product is now different from that of the liquid returned to the column.
The file RR3.BKP has a total condenser and a liquid product, but there is decanter on stage 1 (the condenser). The second liquid from that decanter (the organic, chloroform-rich phase) is not returned to the column. As expected, varying the basis for the reflux ratio from mole to mass the condenser duty changes from -3.1146877 to -3.7240691 Gcal./hr.
Keywords:
References: None |
Problem Statement: What do the history file listings mean (Diagnostics MSG-LEVEL=7) for the observed variables in a Data Regression (DRS) run?
For example:
DATA
MEAS
MEASURED
ESTIMATED
ADJUSTMENT
ADJ/STD
1
1
313.15
313.3551
0.2051122
4.102243
1
2
9.799599
9.778381
0.2112181E-01
-5.737799 | Solution: This portion of the history file lists for:
DATA reports the data set specified in the DATA-GROUP paragraph.
MEAS reports the measurement for the specific data set. For example: a TPxy data set will have for each DATA entry four measurements (one for temperature, one for pressure, one for liquid mole fraction, and one for vapor mole fraction).
MEASURED reports the experimental (entered in the DATA-GROUP paragraph) value of measurement.
ESTIMATED reports the value predicted with the regressed model parameter values.
ADJUSTMENT reports the difference between the measurement (see note below) and the estimate.
ADJ/STD reports the ratio of the adjustment for the measuremernt to the standard deviation assigned to it.
It is important to note that the MEASURED and ESTIMATED values are not those of the property as entered in the DATA-GROUP paragraph but as they are regressed by the DRS system. In order to improve convergence some properties are converted before the paramter optimization begins. The following table lists such conversions:
PROPERTY
SYMBOL
MEASURED PROPERTY/
ESTIMATED PROPERTY
Temperature
T
T
Pressure
P
ln P
Mole-Fraction (V or L)
Z
ln [ Z/(1-Z) ]
Activity Coefficient
GAMMA
ln GAMMA
K value
K
ln K
User Property (*)
U
U
No transformations unless the user specified log forms, in which case the ln U values are employed.
Therefore, in the above example the first measurement reported is the temperature for the data set, while the second measurement reported is the natural logarithm of the system pressure.
The ADJ/STD values (4.1 and -5.73 in the example above) represent
the ratio of the deviation of that point to the standard deviation supplied by the user. Deviations above the low single digits imply that either that measurement was not well fit or the supplied standard deviation was unrealistically low.
Keywords:
References: None |
Problem Statement: How do I save the optimization report as a text file? | Solution: The optimization report can be saved as a text file by adding USE_HTML to the field ID and setting its value to N in Table CONFIG.
Keywords: MBO Report
Optimization report
Report in html
Report in .txt
References: None |
Problem Statement: How can sulfur and other property data be entered for a petroleum assay? | Solution: Petroleum properties require the user to supply a series of 4 or more property values at the corresponding distillation volume recoveries of the assay. If the user has a bulk value in addition, enter the bulk value to force Aspen Plus to adjust the property versus distillation curve result in a calculated average value equal to the specified bulk value.
Once a relationship is established between the property and the distillation curve, then property values can be assigned to each pseudocomponent (the pseudocomponents represent a finite element of the distillation curve). When the flowsheet simulation finishes, Aspen Plus calculates the petroleum properties for each stream by volume weighting the property value assigned to each pseudocomponent in the stream.
The best way to learn this feature is to reverse engineer some of the assays in the Aspen Plus Assay Library (On the Components / Specification form, visit the Petroleum sheet). In the attached example, the assay called ARABLT1, from the assay library, is used. It contains petroleum property data for Aniline Point, Freeze Point, SULFUR, Pour Point, Nickel and Vanadium. The below example focuses on the SULFUR Curve data supplied for this assay.
If you visit the Component folder''s Assay/Blend sub-folder and then look at the Property Curve under ARABLT1, you can see all of the input property curves and their values. In this case,change the Property Type listbox to SULFUR (By default it will display the ANILPT- Aniline Point). Here are the input values:
Mid % Wt%
Distilled Sulfur
--------- ------
12.89 0.037
35.61 0.44
51.13 1.56
70.16 2.46
77.65 3.07
For the above curve, Aspen Plus calculates 2.2 wt% Sulfur for the bulk value (see the stream results in the attached model). If the user had entered a value on the input form for bulk wt% sulfur, the curve would have been adjusted so the volumetric average of each pseudo component equaled the supplied bullk value.
There is one final step, and that is requesting the petroleum properties to be printed in the stream results. First create a property set (or modify an existing one). In the property set, add the appropriate parameter for the petroleum property you wish to track. In the case of SULFUR, the property parameter for the bulk wt% Sulfur is called ''SULFUR''. To view the sulfur curve for each stream, add the parameter called ''SULFCRV''.
In the attached flowsheet, the feed stream is flashed with a vapor fraction of 0.1. The vapor product stream has a calculated bulk wt% sulfur = 0.2, while the liquid product has a bulk wt% sulfur = 2.2. Also included in this stream report is the calculated sulfur curve for each stream. Even though the feed and liquid product stream have a similar wt% sulfur, notice the slight difference in their sulfur curves.
The above methodology applies to all petroleum properties:
Aniline Point Nickel Content
Anti-Knock Index Olefin Content
Aromatic Content Oxygen Content
Basic Nitrogen Content Paraffin Content
Carbon Residue Pour Point
Flash Point Refractive Index
Freeze Point Reid Vapor Pressure
Hydrogen Content Research Octane Number
Iron Content Smoke Point
Luminometer Number Sulfur Content
Mercaptan Content Total Nitrogen Content
Keywords: Petroleum, bulk, RVP, Octane
References: None |
Problem Statement: How does Blend Controller Interface (BCI) read property min/max values? | Solution: Here is how PimsBCI reads min/max of properties:
1. Read limit from AB_BLN_QUALITIES
2. Check PropMap to see whether has a ConversionCode, and do a conversion if the user provides it. E.g. SPG_TO_API
3. Check BpcSpecs table to match the same product and same property, if we find it, override limit according the limit or delta limit value on this BCI table.
4. Correct the min max again
5. If Step 3 can't find any matching row on BPCSpecs table, then try to find record in BPCSpecs table to match “Default” product with same property
6. Repeat step 4.
7. Apply the scale if the user provides it on BPCSpecs table.
Keywords: Blend Controller Interface (BCI), BPCSpecs, AB_BLN_QUALITIES
References: None |
Problem Statement: How do I view the different logs in MBO? | Solution: All the reports concerned with a model can be accessed from within and outside MBO:
1. Iteration Log
2. Express Log
3. Model Errors Log
Accessing from within MBO:
The Iteration and Express logs are as shown here: which are hyperlinked in the final report which is showed when running the optimizer:
For the model errors log: Go to Model-> Validate Model
This will display the model errors log:
Accessing from outside MBO:
By default, all reports/logs concerned with a model are stored in the working directory specified in the model settings dialog box
In the folder, you can find your model reports/logs under the folder named “Reports”
Here above, we can see the Final reports, Iteration logs, the Model Error Log (which has to be opened in notepad), validation report and SBO reports (for running any single blend optimizers) for all cases run in the model.
Keywords: Iteration Logs, Express Logs, MBO, Model Error Logs
References: None |
Problem Statement: Why is there a mismatch in the results reported by the Aspen Air Cooler API sheet and Aspen HYSYS outlet streams? | Solution: When using the integrated rigorous Aspen Exchanger Design and Rating (EDR) tools such as Air Cooler or Shell & Tube Exchanger within Aspen HYSYS, the results such as temperatures reported by the EDR tools in API sheet or TEMA sheet may not match with the HYSYS stream conditions.
The reason HYSYS results do not match rigorous EDR data is because HYSYS does a PH flash calculation after the integration. In these circumstances, the user needs to take a few further steps to match the results. You can check the property range in the EDR browser and remove any specified value. Furthermore, you can disconnect (break connection) and reconnect the outlet streams in the HYSYS Simulation Environment.
Keywords: EDR, TEMA sheet, API sheet, Aspen HYSYS, Results, Property Ranges.
References: None |
Problem Statement: When importing from MBO and reading the data in BCI, we see the MIN_SPEC and MAX_SPEC equal to the TARGET_SPEC. What could be a possible reason for this? | Solution: Min and max value come from database, from the BCI table (GlobalSpecs, BpcSpecs). You may have set the DeltaMinSpec and DeltaMaxSpec to 0 on BpcSpecs table.
Clear these two cell or change to other number, you may get different min and max
Keywords: Blend Controller Interface, BCI, Min_Spec, Max_Spec, DeltaMinSpec, DeltaMaxSpec, Table BpcSpecs
References: None |
Problem Statement: How do I set the convection banks layout with multiple process streams? | Solution: In Input > Heater Geometry > Convection Banks > Layout option EDR allows the user to set multiple process streams but it is limited to the number of convection banks.
The number of streams that can be added is equal with the number of convection banks, considering that one stream will be attached onto the firebox. For example, if the user has three process streams and two convection banks, only two process streams can be set.
The number of convection banks limits the number of process streams that can be added in the layout.
Keywords: Convection banks, multiple streams, layout convection banks
References: None |
Problem Statement: When comparing some published data from MBO, sometimes we have seen that these values don't match with the values shown in the interface. | Solution: MBO publishes two different sets of data; simulation values (EV tables) and optimization results (AB tables). MBO makes some considerations in order to reduce the size of the problem. If you see that the simulation values and the optimization values are too different you can try by changing the next settings:
1. Optimizer property balances. The optimizer considers that property values won’t change during the optimization problem; so it uses the calculated values from each time period. This way the optimization problem is easier to solve. You can set the number of days in which the optimizer will do the property calculation balances during the optimization in the Model/Components dialog box.
We recommend using this setting when properties of the rundowns to the component tanks are very different of the ones specified in the beginning inventory.
2. Residual Tolerance and Objective Tolerance. These are convergence criteria for the optimizer. If a property from the simulation doesn’t match with the optimization values, tighten these tolerances.
Keywords: EV, AB, properties, mismatch, MBO
References: None |
Problem Statement: RVP using ASTM D323-82 correlation doesn't report any values in my process stream and instead the field is 'empty' | Solution: The RVP or Reid Vapor Pressure, can be reported in Aspen HYSYS by adding it as a correlation on a process stream via the Worksheet tab/Properties page.
The RVP ASTM D323-82 method calculates on the assumption that the hydrocarbon stream is saturated with wet air. Thus, the constituents of air need to be present in the component list which is associated to the particular process stream. This means that Nitrogen, Oxygen and Water have to be included in the component list, even though they are not part of the stream composition.
Keywords: RVP, RVP ASTM D323-82, Reid Vapor Pressure
References: None |
Problem Statement: How does Fired Heater calculate Heat Duty in Aspen HYSYS? | Solution: Aspen HYSYS performs energy balance from enthalpies. The efficiency in the heater is the percentage of combustion heat absorbed by the process streams.
Rest of the heat is used to raise the temperature of flue gas from inlet condition to the outlet condition.
Total duty (heat released during combustion) = heat up duty for the flue gas + heat absorbed by the process streams.
Efficiency = heat absorbed by the process streams/total duty.
Note- The fired heater in Aspen HYSYS does not use the heating value to calculate the duty for the fuel gas
Keyword,
Fired Heater, Heat Duty Calculation, Heating Values, HYSYS
Keywords: None
References: None |
Problem Statement: What is HYSYS OLGALink? | Solution: HYSYS OLGALink is an extension to HYSYS which creates a link to the third-party OLGA2000 software. OLGA2000 is a dynamic multi-phase flow simulation package available from Scandpower Petroleum Technologies.
OLGALink allows source and boundary streams of an OLGA simulation case to be connected to Aspen HYSYS streams. The properties (for example pressure, temperature, flow rate, gas-oil ratio and watercut) are passed between the OLGA and Aspen HYSYS simulations as the cases are run simultaneously in dynamics mode.
For more information about OLGA2000, please go to http://www.olgaworld.com/
Keywords: OLGA, OLGALink, Scandpower
References: None |
Problem Statement: When I choose either to Estimate Unknown coefficients or Set All to 0.0, my user specified coefficients don't appear to make any difference. | Solution: When using an EOS fluid package in Aspen HYSYS, in the binary coefficients tab the user has two options:
1. Estimate HC-HC/Set Non HC-HC to 0.0; or
2. Set All to 0.0
If the user has binary coefficient data for some or all component interactions, these may be specified as well. However, in order to ensure that these values are not over-written when the user navigates away from the Properties (Simulation Basis) environment, then option 2, i.e Set All to 0.0, should be selected.
Otherwise, if option 1 is selected, these values will be updated from the Aspen HYSYS databanks, for any temperature dependant binary coefficient, when any changes are made while in the Simulation. Thus imposing HYSYS estimated coefficients on any user supplied coefficients.
Keywords: Binary Coefficients, user-supplied coefficients, Set All to 0.0
References: None |
Problem Statement: How to import PVT data from a third-party modeling software? | Solution: ThisSolution contains a video clip which shows you how to import PVT data from the following third-party modeling software:
PVT Pro from DBR/Schlumberger,
Multiflash from Infochem,
PVTSim from Calsep and
GAP Petroleum Experts.
Please note that the video file is over 77MB in size. If you have trouble downloading it, please check to if your system resource is sufficient to handle large size files.
Keywords: PVT, data import, PVT Pro, Multiflash, PVTSim, GAP
References: None |
Problem Statement: What is PVT Environment? | Solution: The PVT Environment in Aspen HYSYS Upstream is feature access via the Aspen HYSYS Simulation Basis Environment that allows users to import the fluid package, component slate and composition of a reservoir fluid from a third-party PVT modelling software. The PVT environment allows users to import data from
PVT Pro from DBR/Schlumberger,
Multiflash from Infochem,
PVTSim from Calsep and
GAP Petroleum Experts.
Please refer toSolution #119956 for a demo on how to import data from each of these sources.
Keywords: PVT, Environment, PVT Pro, Multiflash, PVTSim, GAP, data, reservoir fluid
References: None |
Problem Statement: Heat Duty and Process Stream Duty do not match. How to fix it? | Solution: If you find the difference between the two enthalpies is not acceptable, you can reduce the difference by reducing tolerances. Change one or both of the following.
1. Increase enthalpy relaxation factor up to 1. A factor of 1 means there is no relaxation.
2. Decrease Convergence criterion (temp.) up to 0.05 C.
The following screenshot shows the form.
Keywords: heat duty, process stream duty.
References: None |
Problem Statement: This is the Blend event from MBO. Note the two text parameters: Description and Comments
This is the text that is required in the XML, coming from the AB_ tables
Now, in the BCI mapping spreadsheet, in the Prodmaps worksheet, there is a description column against each product code.
This is the text that is required in the XML, coming from BCI itself
The sparevalues table has the ability to input user defined strings into the XML, but it is always based on either the Event Seq or the Product code, not both.
How do I display the text/description fields from both the event dialog box and the ProdMaps tables in the final XML file using MBO/BCI? | Solution: There is a setting, which can be used to control blend description data in XML reports. Follow these steps:
1. Set description on ProdMaps table
2. Select PRODMAP.DESCRIPTION as Misc Blend Description
3. On SpareValue worksheet, use two cells to store value from AB_BLN_EVENTS table, set SpareString* equal to them.
Use product BCI code as BlendOrderID.
On VBA code, add Sub BCI_SpareValue(X_Seq) and read the AB_BLN_EVENTS table value and assign Comments and Description to these two cells. The VBA code would refer to PimsBCI sample model.
Run PimsBCI and open this model, the XML receipt should be:
1. Description on ProdMaps table is shown on <BP_Order>/<Description> node
2. Both COMMENTS and DESCRIPTION on AB_BLN_EVENTS are shown as SpareString
Keywords: PIMSBCI, Blend Controller Interface, SpareValues, ProdMaps, AB_BLN_EVENTS, Blend Description
References: None |
Problem Statement: Does the Fouling Resistance of the tubes impact the pressure drop? How is this reflected in the friction factor of the pressure drop equation? | Solution: Changing fouling factors does not directly change anything included in the pressure drop correlation (e.g. roughness). So no specific equation can be given. However it can impact the pressure drop because of changes to the physical properties of the fluid, particularly if the fluid is vaporizing.
Making large changes to the fouling factor will cause significant changes to the outlet conditions of the fluid. Taking the attached standard example QFiredHeater1
if Fouling factor = 0, Outlet temperature = 370 oC , vapour fraction = 1, pressure drop = 3.17 bar
Fouling factor = 0.01, Outlet temperature = 192 , vapour fraction = 0.88, pressure drop = 1.85 bar
Fouling factor = 0.1, Outlet temperature = 172 , vapour fraction = 0 , pressure drop = 0.04 bar
Fouling factor = 0.5, Outlet temperature = 45 , vapour fraction = 0 , pressure drop = 0.04 bar
with Fouling = 0, the exit fluid is pure vapor, with Fouling 0.1 exit vapor is pure liquid. The pressure drop differences are large because of large changes in volumetric flows and velocity. However there is very little difference in pressure between fouling = 0.1 and 0.5 because the exit fluid is liquid in both cases.
Keywords: fouling, pressure drop, correlation
References: None |
Problem Statement: In the Equation Orientated (EO) strategy, all models use a mole flow and mole fraction (or %) by default to report calculated results. How can I access or create an EO variable for the calculated mass flow or fraction of a stream to be used in a spec-group for example? | Solution: strategy
Keywords: Mass fraction
mass flow
Equation orientated
analyser block
References: None |
Problem Statement: How do I report vapor pressure in Aspen HYSYS? | Solution: There is no direct way to report vapor pressure, however you can add a Property Table for each stream and calculate it.
Go to each stream> Attachments Tab> Utilities> Add> Property Table
Then in the Property Table,
Select the Temperature and the Vapour Fraction as the Independent Variables, and setup the Mode for both as State, and the value for the Temperature has to be the same as the temperature in you material stream and define the Vapour Fraction as 0.
Then define the Pressure as the Dependent Property
Press Calculate, go to Performance and see the Pressure which is going to be the vapour pressure,
Keywords: Vapour Pressure, Vapor Pressure
References: None |
Problem Statement: What are the weight % of sulfolane/MDEA or DEA/water in the components “Sulfinol-M” and “Sulfinol-D? | Solution: The Sulfinol-D model is based on the VLE data from Isaacs (1977).
And the composition of the solvent is 40 wt% DIPA + 40 wt% Sulfolane + 20 wt% H2O.
The Sulfinol-M model is based on the VLE data from Macgregor (1991).
And the composition of the solvent is 20.9 wt% MDEA + 30.5 wt% Sulfolane + 48.6 wt% H2O.
Keywords: Acid gas, sulfinol compositions, Sulfinol-M, Sulfinol-D
References: None |
Problem Statement: The Hydraulics PFD fails to solve and produces a message ?Invalid Model?. | Solution: This message appears when the internal diameters of the connected pipes are not the same. To resolve this problem place a swage in between the pipes of unequal internal diameters. See details in the attached document.
Keywords: HYSYS Upstream, Aspen Hydraulics, Swage
References: None |
Problem Statement: Is it possible to have actual Reflux Rate as a column specification? | Solution: There is no option for Reflux Rate in the Expert Input page used for the column configuration.
The following steps are guidelines to add Reflux rate as a column specification :
1. Add the column specification type as '' Column Liquid Flow ''
2. Select the condenser stage
3. Select the flow basis
4. Provide the value for the reflux rate
The liquid flow rate from the condenser represents the reflux flow rate of the column.
Keywords: Reflux Rate , Column Liquid Flow spec, column specifications
References: None |
Problem Statement: Best Practices for Aspen Hydraulics subflowsheet in dynamic mode | Solution: Please find below best practices and recommendations for Aspen Hydraulic models in Dynamic mode.
· PVT table generation.
When using Dynamic or Dynamic3P solver, the fluid properties at a given pressure and temperature are obtained by interpolating a PVT table. The PVT table is generated between pressure and temperature bounds defined by the user so make sure that these boundaries cover the entire simulation range since no extrapolation is performed outside of bounds. In addition, the PVT table is generated at the initial composition of the referenced stream and kept fixed unless the “Enable PVT Table Regeneration� option is selected.
· Dynamic Initialization options
Choosing the right initialization can help the stability and converge of the Hydraulics model. Usually Fixed Hold-up is good; Cold Start is most reliable but is not usually near the Steady-stateSolution.
– Cold Start
§ Fluid initially at rest at specified pressure and temperature in the “User Dynamics Initialization�
§ Initial gas hold-up is also specified (starting in V8.8)
– Fixed Hold-up
§ Constant gas hold-up specified in the “Fixed Gas Holdup� field
§ Pressure and temperature from steady-state
– HTFS
§ Hold-up calculated with HTFS method
§ Pressure and temperature from steady-state
– Homogeneous
§ Hold-up calculated with homogeneous method
§ Pressure and temperature from steady-state
– Steady-state
§ Hold-up, pressure, and temperature from steady-state
· Vertical Flow Initial Conditions
o Dynamic model tends to predict higher liquid hold-up than most steady-state models and hence higher pressure drop. Due to this, specifying inlet flow could lead to failure of the solver if pressure drop is too different from initial conditions.
o When having high gas fraction, Cold Start or Fixed hold-up work best.
o When observing issues, start simulation with lower flow-rate to evaluate pressure drop; once initialized flow rate can be adjusted.
· Model Spatial Discretization
Although there are no definite recommendations, avoiding large changes in cell size between pipes is a good tip. For example, a pipe with 0.1m cells connected to a pipe with 100m cells will often cause instabilities or convergence failures.
Also, use your engineering criteria to keep the pipe sections as simple as possible, not every rise and fall is always necessary. When having liquid in the system focus on understanding where the critical hold-up will be.
· Time-step size
When observing convergence issues, time-step size is one of the first things you should review. Usually decreasing time step allows the Hydraulic solver to reach convergence faster while keeping stability.
NOTE: Remember Hydraulic solver has its own control of Time Step of integration, it can be found in the Dynamic tab of the Hydraulic subflowsheet window.
· Product Pressure Relaxation Factor
This can be manipulated when large changes in pressure at boundaries are observed, helping the stability of the model.
· Running the case alone.
It is a good idea to run the Hydraulic subflowsheet without any connection to the main flowsheet beforehand to confirm stability and convergence of the case.
Keywords: Aspen Hydraulics, HYSYS, Upstream, Dynamics, Steady State, Pipe
References: None |
Problem Statement: How do I use an old Fortran subroutine from Aspen Plus 9 in version 11?
There used to be a utility called ap9to10 that would convert Fortran files, but I cannot find it now. | Solution: As per the release notes (What''s New in Aspen Engineering Suite (AES) 11.1, page 4-13 ), AP9TO10 is not supported in 11.1. This is due in part to the componentizaton of Aspen Properties and changes in directory structures that accompanied it.
Customer Support can convert files for customers who do not have access to a 10.x version of Aspen Plus.
Aspen Plus 10 Fortan files can be used directly in Aspen Plus 11.
Keywords:
References: None |
Problem Statement: Unable to install PIPESIM without selecting the subfeatures from Aspen HYSYS Upstream | Solution: Select HYSYS UPSTREAM and selected the sub-features.
Then unselect the sub-features and continue the installation.
Keywords: HYSYS UPSTREAM
PIPESIM
References: None |
Problem Statement: Is it possible to see the values of the calculated heat transfer coefficients on the tube side and shell side? Currently, HeatX displays only the overall heat transfer coefficient. | Solution: They are displayed in the report file only if you select the option Include profiles in report in Options, Report sheet of the HeatX block.
You can display also the heat transfer coefficients on the tube side and shell side separately in the history file. To activate the print-out of these values during the calculations of the HeatX block, change under Block Options, Diagnostics the Simulation reporting level to 7 or more. After running the simulation, you can view the results in the history file. Search for lines such as:
ZONE= 1 Q=0.23670E+06 AREA= 22.079
POINT=1 HS= 93.476 HT= 1209.3 U= 85.292 DT= 127.59
ZONE= 2 Q=0.15906E+07 AREA= 29.336
POINT=1 HS= 1592.5 HT= 1015.2 U= 542.68 DT= 87.036
ZONE= 3 Q=0.25423E+06 AREA= 19.274
POINT=1 HS= 227.61 HT= 796.60 U= 168.63 DT= 80.027
F= 1.0000 AREA= 70.689
I = 1 Q = 0.20816E+07 AREA = 70.689 ERR = 0.42805E-04
This is an example with 1 point (Number of points per zone for film coefficient calculation in Options, Convergence) and 3 zones. HS is the shell side film heat transfer coefficient, HT the tube side, U the overall coefficient and DT the temperature difference. HS, HT and U are in W/sqm.K.
Note that the overall heat transfer coefficient reported (in history and report file) is calculated from:
1/Uot = 1/nus*(fs + 1/hs) + RA*(1/ht + ft) + rw
where:
Uot is the overall heat transfer coefficient (W/m2/K)
nus is the 1 for bare tubes
fs is the fouling coefficient shell side
hs is the film transfer coefficient shell side
RA = Dto/Dti for bare tubes
Dto is the tube outer diameter
Dti is the tube inner diameter
ht is the film transfer coeffiicent tube side
ft is the fouling coefficient tube side
rw = Dto/2/kw*ln(Dto/Dti)
kw is the tube thermal conductivity
When a scaling coefficient is applied, the reported value of U is Uot*scaling.
Keywords: film
References: None |
Problem Statement: If a user has created a simulation using one of the new Refinery templates-
Aromatics- BTX column and Extraction,
Catalytic Reformer
Crude Fractionation
Customized Stream Report
FCC and Coker
Gas Plant
Generic with Customized Stream Report
HF Alkylation
Sour Water Treatment
Sulfur Recovery
there is an error message that the following Engine files are missing - usrpp1b.dat. Do you want to continue? | Solution: To get rid of the error user should delete the reference to the usrpp1b.dat file in Run/ Settings/ Engine files / usrpp1b.dat.
Keywords: Refinery, templates, usrpp1b.dat
References: None |
Problem Statement: Why does the area calculated using PI*D^2/4 for a type D Relief valve differ from the area provided in the NBBI Redbook (NB-18) for Farris Series 2600 Type D valve? | Solution: Looking in the Aspen Plus Pressure\Relief\Safety Valve sheet for the Farris 2600 Type D valve, the diameter for this valve is 0.437 inches, which gives an area of 0.15 inches squared.
NOTE: Although manufacturers list Relief Valves as Type D or H etc... in reality they can all have differing areas due to differing diameters, for example the Dresser 1900 series valve, which has a diameter 0.4036 inches has an area of 0.1279 which is less that that for the Farris 2600 Type D valve.
For the Actual capacity run we do not derate the capacity of the relief device as specified by ASME code requirements, gives best estimate relief device effluent and calculate the area as follows:
PI*D^2/4 * 0.953 (0.953 is the Discharge coefficient)
In the Code capacity run, we derate capacity of the relief device as specified by ASME code requirements and multiply the value by 0.9.
PI*D^2/4 * 0.953 *0.9
For more information on the NBBI Red Book (NB-18), is available at no cost Click here http://www.nationalboard.org/Redbook/redbook.html to get to a page from which you can download it.
Keywords:
References: None |
Problem Statement: AspenTech and BR&E released information referring the integration/availability of TSWEET physical property database in Aspen Plus Release 11. What is the status on this interface?
How can this interface be accessed? Is there an additional AspenTech license required or is it available (or will be available)for companies who has already licensed TSWEET software? | Solution: This interface is available in Aspen Plus 11.1, 12.1 and 2004. This interface is not available in Aspen Plus 2004.1 and higher.
The interface includes six additional property methods: 2 for Amines (BRE-NRTL and BRE-KE), 2 for Methanol (MEOH-SRK and MEOH-PR), 2 for Glycols (DEHY-SRK and DEHY-PR).
The TSWEET feature is a COM component, so you will just install the BRE software on the same PC as Aspen Plus. Our code will try to find it; if it is there, it will be used.
This will be a licensed product.
Contact BR&E (Bryan Research & Engineering, Inc.) to find out more information about TSWEET - http://www.bre.com.
Aspen Plus 11.1 Installation Instructions
For Aspen Plus 11.1, there are some special installation instructions.
Install the Aspen Plus 11.1 Service Pack 1 Cumulative Hot Fix 1 (CH1). The version will then be 11.1.4. (Go to Help \ About Aspen Plus to see the version number.)
Click this link to go to the download page:
http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=110874
In addition to CH1, install APlusHotFix11.1.4.030903 to update the BRE interface to use the latest type library from BRE.
Click this link to go to the download page:
http://support.aspentech.com/webteamcgi/SolutionDisplay_view.cgi?key=112177
Keywords: BRE
TSWEET
References: None |
Problem Statement: What are the water solubility (solu-water) calculation methods and how are they used? | Solution: The water solubility (solu-water) method is specified in the Petroleum calculation options section of the Properties | Specifications | Global sheet or of a block's Block Options | Properties sheet.
These methods affect the liquid fugacity of water accordingly:
In the organic phase when using free-water or dirty water
In the liquid phase when using a vapor-liquid flash
If a rigorous vapor-liquid-liquid 3-phase flash is specified, the water solubility option is forced to a value of 3 and other options are ignored.
For chemical systems such as water-higher alcohols, free-water or dirty-water calculations do not apply. Solubility of the organics in the water phase is significant. Rigorous three-phase calculations are required.
Water Solubility Option
Description
K-value of water calculation from
0
Solubility data and ideal vapor
Water-solubility correlation with the vapor phase fugacity of water calculated by the free-water phase property method.
1
Solubility data
Water-solubility correlation with the vapor phase fugacity of water calculated by the primary property method.
2
Solubility data and correction
Method 1, but include activity coefficient correlation. Recommended for unsaturated systems.
3
Global method
Primary property method. The appropriate binary interaction parameters for water are required.
4
High water solubility for VLE
Method 2, but water solubility limit is 1. Intended for VLE systems where the liquid phase is predominantly water.
5
Solubility data and correction and ideal vapor
Method 2, but vapor phase fugacity calculated by the free-water phase property method as in method 0.
The K-value of water in the organic phase (for both free-water and dirty-water calculations) is:
Where:
= The activity coefficient of water in the organic phase
= The fugacity coefficient of pure liquid water, calculated using the free-water property method
= The fugacity coefficient of water in the vapor phase mixture, calculated using the primary property
method
You can select the calculation methods for and using the Water solubility field on the Properties Specifications Global sheet or the Block Options form.
Solu-water option
Calculate from
Calculate from
0
Free-water property method
1
Primary property method
2
where when =
Primary property method
3
Primary property method
Primary property method
4
Primary property method
5
where when =
Free-water property method
Solu-water option 3 is not recommended unless binary interaction parameters regressed from liquid-liquid equilibrium data are available.
The limiting solubility of water in the organic phase is calculated as a mole fraction weighted average of the solubilities of water in the individual organic species:
Where:
= Water-free mole fraction of the ith organic species
= Mole fraction solubility of water in the ith species
The value of is calculated as a function of temperature, using the Water Solubility model (WATSOL).
Keywords: None
References: None |
Problem Statement: Utilities - Using type :steam or cooling water, what is the property method used? | Solution: Steam and Water utilities use the global free-water property method for the calculation (under Properties \ Specifications under Petroleum calculation options).
Keywords:
References: None |
Problem Statement: Reconciliation in Aspen Plus refers to copying the results of a sequential modular run to the input forms of blocks and streams. Why is this feature in Aspen Plus and when & how should it be used? | Solution: Reconciliation can be very useful when a flowsheet takes a long time to converge. At a point close to theSolution, or better yet after finding aSolution, reconciling streams, which are used as tear streams, and blocks which have their input changed, for instance when using design-specs, will help the next run considerably and allow the user to continue working with backup files rather than having to rely on apw files which take much more space and are not upwards compatible. If all results are reconciled, the flowsheet will have a very good starting point and will converge very quickly. This is very important for large flowsheets and when using Equation Oriented mode.
For Stream Reconciliation please checkSolution 102354 <http://support.aspentech.com/webteamasp/KB.asp?area=PDO&ID=102354>
Design Specs, Calculator blocks, or other manipulations to flowsheet variables (including EO) can modify the value of a block input variable during a run. When the run completes the result for the variable is different from the input given by the user and to flag this you will see in the Data Browser that the block has results Available, Unreconciled.
Input Reconciliation refers to refreshing the sequential-modular input values which have been modified during a run. You can perform input reconciliation of all variables or just all streams from the commands available on the Run menu (Reconcile All and Reconcile All Streams). It is best to have a bit more control over what you are choosing to reconcile and you an easily do this by clicking the block or stream that you want to reconcile with the right mouse button and choose reconcile from the pull down menu...
The following flowsheet objects have full input reconciliation:
Compr, Flash2, FSplit, Heater, HXFlux, MCompr, Measurement, MHeatX, Mixer, Mult, Pump, RStoic, RYield, Streams (including material, heat, and work streams), Sep, Sep2.
In the following blocks Input Reconciliation is partially supported, with these limitations:
HeatX - Only shortcut specifications are reconciled, and not minimum temperature approach, minimum allowable LMTD correction factor, or number of shells.
Decanter - KLL coefficients, solid entrainment fraction, and the threshold mole fraction for identifying 2nd liquid phase (when key components for the 2nd liquid phase are specified) are not reconciled.
Extract - Pseudostreams are not reconciled.
PetroFrac - Furnace specifications, heater duty, stripper liquid return specifications, stripper feeds, runback specifications, rating and sizing specifications, and thermal efficiencies are not reconciled.
RadFrac - Threshold mole fraction for identifying 2nd liquid phase (when key components for the 2nd liquid phase are specified), subcooled reflux specifications, thermosiphon reboiler specifications, efficiencies based on individual phases for 3-phase calculations, decanter specifications, section-based pressure drops and efficiencies, heat loss profiles, reaction residence times, rating and sizing specifications, and user KLL coefficients are not reconciled.
All input variables specific to rate-based calculations which can be manipulated are reconciled.
The following flowsheet objects do not support input reconciliation:
Analyzer, Distl, DSTWU, Flash3, MultiFrac, Pipe, Pipeline, RBatch, REquil, RGibbs, RPlug, SCFrac, Selector, SSplit, and Valve.
Also, all solids models do not support input reconciliation:
Crystallizer, Crusher, Screen, FabFl, Cyclone, VScrub, ESP, HyCyc, CFuge, Filter, CCD, SWash, Dryer, Granulator, Classifier, Fluidbed, and CFFilter.
Keywords: None
References: None |
Problem Statement: Why does my .apw file continually keep growing and growing?
The file size can increase so much that it makes it unable to use run button | Solution: The .apw files do grow with additional information. We allocate large chunks of memory for data If one bit of information remains then that chunk is not cleaned up. After a while the file can become large and fragmented.
We recommend always having a .bkp file and starting from that periodically. In Aspen Plus 11 and higher, it is also possible to reconcile both streams and blocks which makes it much easier to converge a flowsheet after reinitializing without using the previous results stored in the .apw file.
One other suggestion is to make sure that the control panel is not filled with messages in the .apw file. The messages can be deleted by using the Purge messages button on the control panel to get rid of the messages without reinitializing.
Keywords: apw
backup
size
increase
References: None |
Problem Statement: I found that I got much better results if I removed a component from the Constraint list for a vapor-liquid equilibrium (TPXY) data-group in data regression run (DRS). Is this recommended? | Solution: It is recommended to remove completely non-volatile components from the Constraints tab on the Experimental data. The constraint is that the vapor fugacity is equal to the liquid fugacity for each component listed on the Constraint tab. If a component is not volatile (such as a polymer, or an ion, that exist only in the liquid phase), the regression may fail due to such constraint. In that case you should remove such components from the Constraints tab.
In the other hand, if the component is slightly volatile, it is not recommended to remove the component. You may find that the regression is apparently better, but it will not satisfy the basic thermodynamic requirement of vapor-liquid equilibrium (VLE).
Keywords: None
References: None |
Problem Statement: How does Orion/MBO convert Volume and Weight units when both values are entered? | Solution: If the user enters both WGT (weight) and VOL (volume), the following procedure is used by Orion/MBO to resolve differences, before starting the simulation:
1) if SPG is missing set it to 1.0
2) if VOL is > 0 then recalculate WGT. using the formula for weight below.
3) if VOL is equal to 0 or missing then use WGT to calculate VOL using the formula for volume below.
4) if both VOL and WGT are missing set VOL and WGT to 0.0.
5) if WGT>0, then VOL is recalculated from WGT using the formula for volume below.
In SETTINGS| Model Settings Tab enter the volume-to-weight conversion factor (weight factor or VTW). This factor should be consistent with the text entered in the Volume Units and Weight Units fields. (e.g., 1587 MeTon/Bbl, 1.0 MeTon/M3, 0.175 Tons/Bbls, 0.35 MLbs/Kbbls, or 350 Lbs/Bbl.)
The system converts between volume and weight using the following formulas:
Weight = Volume * SPG* Weight Factor
Volume = Weight / (SPG * Weight Factor)
Keywords: -volume-to-weight Conversion factor
- Model Settings
References: None |
Problem Statement: Why am I not seeing the aqueous phase flow on the hydraulics sub flowsheet? | Solution: Hydraulics in Steady state will not recognize the three phases (vapor, liquid and aqueous phases) as in the Main Simulation Environment. This is because Hydraulics does not work like regular HYSYS. It will solve in terms of pipe unit operations rather than streams (like in HYSYS) so the pressure drop correlation will be the most important and it will assume the two liquid phases just like one inside the Hydraulics sub flowsheet.
Keywords: aqueous, hydraulics
References: None |
Problem Statement: Sensitivity block is reporting an error when varying the number of stages in a column. | Solution: Using a sensitivity analysis that varies the number of stages on a RadFrac defined with feeds to bottom stage (e.g a Recitfier) you should use a Calculator block to assign the new feed stage and bottoms product stage value for each stream. Skipping this step may cause convergence problems in the column during the sensitivity run or convergence to wrong results. The convergence issues are then not picked up by the Sensitivity case and the user is induced in error by its results.
Attached is an example containing a Calculator block (called a Fortran block prior to Aspen Plus 10.2), C-1, which is equating the feed and bottom product stage number the number of stages. The block is executed before the RadFrac block to ensure the new value provided by the Sensitivity case is taken by the variables in the Column.
The user also needs to ensure that the number of stages input in the column block (base case) is the maximum number of stages used in the sensitivity block. If not, there is not enough space allocated for the arrays and there will be an access violation.
Keywords:
References: None |
Problem Statement: What do I need to use Pipesys in Aspen HYSYS? | Solution: Aspen PIPESYS pipe segment is an extension unit operation in Aspen HYSYS. In order to use PIPESYS; you should have a separate PIPESYS license from SPT group and make sure that the extension is registered in your machine.
AspenTech used to provide the PIPESYS license included in the installation of old versions of Aspen HYSYS. However, after 31st October 2010, AspenTech no longer offers the PIPESYS license and the users need to contact SPT Group directly to buy this license.
What AspenTech is providing in the new versions is the extension to make the link between the two programs. This is available in all versions of HYSYS including the newest ones (V8.X)
This extension is automatically registered when you install Aspen HYSYS. The location of the dll file is C:\Program Files (x86)\AspenTech\Aspen HYSYS V8.6\Extensions\pipesys.
In the Aspen HYSYS V8.X, you can check for it in the customize menu and Register extension option.
You can then add an Aspen PIPESYS pipe segment to your Aspen HYSYS simulation. This is found in the Palette under the group Custom.
Keywords: pipesys, pipe
References: None |
Problem Statement: How to change Molar Density (DNLDIP) property parameter values in Aspen Properties database for use in HYSYS ? | Solution: To change any property parameter values, you need to have access to the Aspen Peoperties files (either the bkp or the aprbkp files). The first step is to open any of these files in Aspen Plus (in case you have access to the aprbkp file, you need to import it into Aspen Plus).
When inside Aspen Plus, the property parameter values can be entered by the user. In the Properties environment, components can be selected and their property parameter values can be modified.
Under the “Methods” folder the “Parameter” folder can be used to enter property parameter values. The “Pure component” or “Binary Interaction” parameters can be edited in this folder.
The molar density property parameter values for pure components can be modified by selecting the Pure Components folder and then selecting the T-Dependent correlation. There are a variety of correlations that can be selected.
For more information about the differences between these correlations the on-line help can be invoked by clicking F1.
Once the selection is made, the page for this property parameter (DNLDIP) can be modified.
Finally, the updated bkp of aprbkp file can be imported into HYSYS
Keywords: Aspen Properties, Physical Property Parameter, Molar Density, DNLDIP
References: None |
Problem Statement: How do I specify the sections in which the pipe segment is divided in hydraulics? | Solution: The hydraulics pipe segment allows you to select the number of pipe cells in Design / Data.
The Pipe Cells represent the number sections in which the pipe segment is divided for calculation purposes.
This is equivalent to the Increments in the Hysys pipe segment.
For example, if 5 Pipe Cells are specified, the pipe will be divided in 5 sections which will generate 6 points. This can be seen in the Profiles Page located in Performance.
Keywords: Pipe Cells, Increments, Profile
References: None |
Problem Statement: How do I find the wall temperature of pipe in Aspen Hydraulics? | Solution: To obtain the wall temperatures the user first needs to configure the detailed heat loss model in the pipe segment.
When the Hydraulic flowsheet is converged the temperature profiles will be shown in the Insulation page under the Performance tab as shown below.
Keywords: Wall Temperature, Pipe in Hydraulics
References: None |
Problem Statement: Does the PIPESYS extension work with black oil streams? | Solution: As shown in the figure below, the PIPESYS extension is compatible with black oil streams. Please refer to the attached simulation file for an example.
Keywords: black oil, PIPESYS, extension
References: None |
Problem Statement: Why are so many property parameters missing for Helium? | Solution: The most common isotope of Helium is Helium-4.
There is a component named Helium-4 in Pure10 and Pure11 that has a fairly complete set of property parameters. Helium-3 is a minor isotope that is also available in the Purexx databanks.
Starting in Aspen Plus 11.1, a component named simply Helium with a formula of He was added to the Inorganic databank; however, hardly any pure component parameters are available for it.
The problem is that if a component is given a name of Helium then the Helium in the Inorganic databank will be found since it is an exact match. In Aspen Plus 10 and earlier, Helium-4 was found and used since the exact match in the Inorganic databank was not present.
Wordaround
Use Helium-4 instead of Helium.
Fixed in Version
HE was changed to HE-4 in the inorganic databank for Aspen Plus 12.
Keywords:
References: None |
Problem Statement: How you can choose part of the flowsheet (a hierarchy for example) to be solved in sequential-modular (SM) while the rest is solved in Equation-Oriented (EO) mode? | Solution: The mixed mode strategy enables you to solve individual
hierarchies in SM or EO. The overall strategy is then considered
SM. This feature is only available in simulation mode.
This mode is useful to
Migrate flowsheets one section at a time from SM to EO.
Converge flowsheets where one section has many tear streams and does not converge well in EO. For example, a crude column with a complex heatx preheat section could converge fastest with the column in an EO section and the preheat section in SM.
Use a SM Sensitivity block, but still have most of the flowsheet solve quickly using EO.
Use the sheets of the EO Convergence Options Setup form to
specify the sequential-modular to equation-oriented (SM-to-EO) and
equation-oriented to sequential-modular (EO-to-SM) switch
parameters used with mixed mode.
On the SM Init sheet, specify the SM initialization parameters at the hierarchical block and flowsheet levels.
SM Init Parameters Description
Maximum flowsheet evaluations
The maximum number of flowsheet evaluations
(default 3)
Wait
Number of direct substitution iterations before
the first acceleation iteration
(default 2)
Consecutive direct substitution steps
Number of consecutive acceleration iterations
(default 2)
Diagnostic message level
Level of errors and diagnostics printed in the history file
(default 4)
Lower bound
Lower bound for the Wegstein acceleration parameter q
(default -5)
Upper bound
Upper bound for the Wegstein acceleration parameter q
(default .9)
On the SM to EO sheet, specify the sequential-modular to
equation-oriented (SM-to-EO) switch parameters that are used
at the hierarchical block and flowsheet levels in the Mixed
ModeSolution strategy.
SM to EO Switch Parameters Description
Maximum initialization passes
The maximum number of SM initialization evaluations
(default 2)
Tolerance
The tolerance for sequential-modular initialization
(default 0.001)
Bypass SM initialization
When set to yes, sequential-modular initialization
is bypassed if block and streams have been
previously initialized
(default no)
On the EO to SM sheet, specify the equation-oriented to
sequential-modular (EO-to-SM) switch parameter that is used
at the hierarchical block and flowsheet levels in the Mixed
ModeSolution strategy.
EO to SM Switch Parameter Description
Maximum iterations
The maximum number of iterations after (default 2)
failure of the equation-oriented (EO)Solution before switching back to the
sequential-modular (SM)Solution method
Keywords: equation oriented
EO-CONV-OPTIONS
References: None |
Problem Statement: Moving the ''Program files'' folder (or its contents) back and forth damages the shortcuts to the Aspen Plus Simulation Engine.
Explanation
Once Aspen Plus 10.2 is installed on Windows, shortcuts to the different .bat and .exe files are created.
The shortcut to the executable program that opens the Aspen Plus GUI, APWN, contains as target:
D:\Program Files\AspenTech\Aspen Plus 10.2\GUI\xeq\apwn.exe
However, the shortcut for the AspenPlus SimulationEngine contains the path written using DOS 8.3 equivalent names.
Furthermore, this notation is also used in the AspSetup.BAT file that sets the environment for the Simulation Engine window:
D:\PROGRA~1\ASPENT~1\ASPENP~1.2\Engine\xeq)
If a user rebuilds the directory structure, the DOS names are re-assigned and may be different from the original ones!! The result is that the shortcut to the Simulation Engine will not work anymore and the AspSetup path settings will also be erroneous.
For example, this situation could occur if
A drive crashes, and it is restored from a backup tape that has no actual image of the drive but is using file-system calls to recreate folders and copy files.
A user wants to defragment or compress a drive and copies back and forth the Program Files folder and all its contents. | Solution: Correct the shortcut to the Simulation Engine in the Start menu. (Start Menu - Programs - AspenTech - Aspen Engineering Suite - Aspen Plus 10.2 - Aspen Plus Simulation Engine)
Edit the AspSetup.bat file located in ..\Program Files\AspenTech\Aspen Plus 10.2) and correct the path assigned to the asptop environment variable. Set asptop=....
Run the C:\Program Files\AspenTech\Aspen Plus 10.2\GUI\xeq\Apwnsetup.exe utility to update the registry entries.
Keywords: Shortcuts - Simulation engine - Programs - Path - Short filenames
References: None |
Problem Statement: How do you add components to the FACT databank? | Solution: Below are the instructions about how to
add components to the Aspen Plus engine and the Aspen Plus User Interface. This is a general process that is applied to the FACT databank.
Overall, there are two steps,
Use DFMS to add the new components to the FACTPCD.
Customize the GUser Iinterface.
Keywords: chemapp
sage
interface
References: s:
Engine Customization (DFMS): Physical Property Data 11.1 Reference Manual, Chapter 1, Databanks. User Interface Customization: System Management 11.1 Reference Manual, Chapter 4, Configuring Physical Property Databanks.
These manuals are available from the Documentation CD or you can download them from our support web site: http://support.aspentech.com and click on the Documentation link on the left hand frame.
Engine
The engine customization files are included in the zip file.
There are 7 since Aspen Plus has a limit to the number of
components in one file. There are two pieces that a user
would need to add to FACT7.inp. The first section is the
NEW-COMP section.
The first field is the component name (xxxxx:yyyy) as above. The second field is an alias - limited to 12 characters.
This is used primarily to indicate different numbers for
different phases of the same molecule.
The second is in the PROP-DATA section. A new component
would require one line in each section. Again at the end of FACT7.inp there are ZZDUM dummy components. The first field is PVAL The second field is the component name enclosed in
single quotes. The third sections is the molecular weight.
Everything after the molecular weight is the same for all
components in FACTPCD.
After modifying FACT7.inp, you need to run DFMS on all
FACT*.inp files in numerical order.
Steps:
Modify the Fact7.inp.
Open the Aspen Plus Simulation Engine window, run the following command in the directory where the input files are located:
dfms fact1
dfms fact2
dfms fact3
dfms fact4
dfms fact5
dfms fact6
dfms fact7
Confirm that factpcd.dat is created under c:\Program Files\AspenTech\APRSYSTEM 11.1\Engine\dat
User Interface
The User Interface customization file is factpcd.dat. It is located in C:\Program Files\AspenTech\APRSYSTEM 11.1\GUI\custom in the
default installation. After the first
few lines of header information, each component gets 3 lines. The first field on the first line is the component name
truncated to 12 characters, the second field is the full
component name. The first field of the second line is the
molecular weight. All other information is identical for all components. Note that at the end of the file,
a number of dummy components (ZZDUM101 to ZZDUM114) are included. In the case of FACTPCD components, the structure is
xxxxxx:yyyy, where xxxxx is the name FactSage understands and yyyy is the phase (e.g. C2AF). The total length of a
component name is limited to 32 characters and the yyyy
section is limited to 4 characters.
Steps:
Modify factpcd.dat.
Open the A+ simulation engine window, go to c:\programfiles\AspenTech\APRSYSTEM 11.1\GUI\custom
then run the command: mmcustom mmtbs
Verify that the databank is correctly installed, by opening the file custom.bkp located in directory \ProgramFiles\AspenTech\APRSYSTEM 11.1\GUI\custom. This uses the modified RecDef file locally. Include your databank at the top of the Components Specifications Databanks Sheet and search for any component from your databank.
If Step 3 is OK, install the modified files by entering custinst at the DOS prompt.
Notes:
Add new phases also need to be identified in FACTSOLN.TXT. |
Problem Statement: Which parameters should I regress when using isothermal VLE or LLE data to regress binary interaction parameters for an activity coefficient model? | Solution: The excess Gibbs free energy has the general form:
E n E E
g = RT Sum ( x ln gamma ) = h - Ts
i i i
AspenTech's activity coefficient model temperature dependencies are of the form (Aspen Plus 8.5-6 and earlier have a and b, Aspen Plus
9.0 and higher have additional terms e and f):
ln gamma ~
a
+
b / T
+ e lnT + f T
i
ij
ij
ij ij
Therefore, you can express the excess Gibbs free energy as:
E n E E
g = RT Sum x ln [ a + b / T + ... ] = h - Ts
i i ij ij
Isothermal regressions must use one of the two accepted limiting behaviors for the representation of liquidSolutions:
the ATHERMALSolution limit, where the components mix at constant temperature without change of enthalpy (heat of mixing is zero):
E E
g = - Ts
n E
RT Sum ( x ln gamma ) = - Ts
i i i
cancelling temperature on both sides gives the result:
n E
R Sum ( x ln gamma ) = - s
i i i
E
Since -s can be considered independent of temperature, ln gamma should also be independent of temperature.
Since ln gamma ~ a + b / T, regress the a parameter from isothermal data for an ATHERMALSolution.
the REGULARSolution limit, where there are no configurational effects upon mixing:
E E g = h
n E
RT Sum ( x ln gamma ) = h
i i i
n E
Sum ( x ln gamma ) = h / RT
i i i
E
Since h can be considered independent of temperature, ln gamma should vary with 1/T.
Since ln gamma ~ a + b/t, regress the b parameter
from isothermal data for a REGULARSolution.
Use the athermalSolution assumption (a) when variations in the molecular configurations dominate the mixing effects. Such systems may show small energetic imbalances, but large entropic imbalances (size and shape differences) with pronounced density variations (for example, mixtures of polymers with their monomers).
Use the regularSolution assumption (b) when imbalances in component interaction energies dominate the mixing effects. The heat effects upon mixing are great, but the molecules are simlar in shape and size.
Both limits represent extreme behavior and neither is entirely correct. However, the regularSolution limit better represents most traditional chemical process industry systems because they normally process molecules of
similar sizes and shapes.
NOTE: Interaction parameters from DECHEMA assume REGULARSolution behavior. (DECHEMA does not have a term equivalent to the AspenTech term in its activity coefficient models.)
Keywords:
References: : R.C. Reid, J.M. Prausnitz and B.E. Poling, The Properties of Gases and Liquids. 4th Edition, pgs. 262-263. |
Problem Statement: When VBA code tries to hide a Design-Spec that is already hidden in an Aspen Plus model, an error is returned. Is there some way to check if the Design-Spec is already hidden before accidentally trying to hide it again? | Solution: There are a few different ways that this can be done.
Option 1
Probably the easiest way to detect when a particular Design-Spec is already hidden, is to use the On-Error checking and then try to hide the Design-Spec. If it is already hidden, you will get an error message.
Example code:
Private Sub cmd_HideDes_Click()
On Error GoTo myhandler
go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).hide (DS-1)
MsgBox successfully hid the DS, vbInformation, DS Hide SUCCESS!!!
Exit Sub
myhandler:
MsgBox can't turn off the DS - it is already hidden or deleted
On Error GoTo 0 ' turn off on-error checking
End Sub
Option 2
Count the number of Design-Specs and search for your Design-Spec (MyDSName) by a name search.
Example code:
dim DsName as String, MyDSName, dsCount as integer, DSnameFound as boolean
'
DSnameFound = False
dsCount = _
go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).elements.count
for i = 0 to dsCount -1
dsName = go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).elements.item(i).Name
if DsName = MyDSname then DSnameFound = True
next i
if DSnameFound = False then
msgbox The Design-Spec & MyDSname & is already hidden
endif
Option 3
Ask the parent how many hidden children it has.
Example code:
go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).AttributeValue(HAP_CANREVEAL)
Option 4
Create your own boolean variable for each Design-Spec and set the variable to true or false everytime you hide or reveal a Design-Spec.
Example code:
Global HideDS1 as Boolean 'place in your module code
...
go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).Reveal (DS-1)
HideDS1 = False
'
go_Simulation.Tree.Data.Elements(Flowsheeting Options).Elements(Design-Spec).Hide (DS-1)
HideDS1 = True
Keywords: activex, visual basic, VB, VBA, Excel, design spec, design specification, hide, error
References: None |
Problem Statement: I have heat of vaporization data for a substance, and I''m trying to fit the first two elements of parameter DHVLDP. I know that element 1 is roughly 1E7, and element 2 is roughly 0.1. However, if I enter these values for the scale factors on the Properties--> Regression form, my regression run appears to converge, but the fit is not very good. In fact, my results seem better when I set the scale factors equal to one. What is wrong? | Solution: The problem is due to confusion about Aspen Plus''s definition of the term scale factor. In the Aspen Plus data regression system, scale factor is actually used as a multiplier. The scaled quantity is computed as the quantity multiplied by the scale factor.
To help the regression, the aim should be to have the product of the value times the scale factor for each element to be approximately 1. For the problem statement above, the user should set the scale factor as 1.0E-7 for the first element, and 10.0 for the second element.
When the parameter scale factors are set incorrectly at 1.0E+7 and 0.1, the regression run does not move the estimate of DHVLDP/1 from its initial value of 4.9E+7. The final weighted sum of squares is 688. A plot of experimental and estimated values is shown in the attached file.
In contrast, when scale factors are set correctly at 1.0E-7 and 10.0, the final estimate for DHVLDP/1 is 5.214E+7, which is noticeably different from the initial parameter estimate. The final weighted sum of squares is 12.4, indicating the fit is much better. The improved quality of the fit is illustrated in the attached file.
Note that if the user misinterprets the scale factor as a divisor rather than a multiplier, the impact on the data regression is greatest when the order of magnitude of the parameter is very large or very small. Further, a clue that the scale factor has been incorrectly applied is that the regressed parameter will remain at its initial guess.
The plots referred to above, along with the .bkp file used to generate the plots, are contained in the attached file ScaleFactors.zip. The backup file can be opened in Aspen Plus 11.1 and higher.
Keywords: Regression, Scale, Scale Factor
References: None |
Problem Statement: How will ICARUS be integrated into the Aspen Engineering Suite (AES)? | Solution: Aspen Tech acquired ICARUS corporation to enhance our customers'' engineering decision making. With the ICARUS product family, AspenTech now has the ability to enhance engineering knowledge with economic knowledge, providing a truly powerful offering.
The ICARUS product family is now part of the Aspen Engineering Suite. While detailed development plans are being defined, we anticipate that AES 11.1 will have the first product integration with focused value-adding enhancements. AES 12.x will have more thorough product integration, to further enhance our customer''s ability to unite and compress their engineering workflow, and optimize their Asset Value Chain.
We will post more detailed development plans as they become available.
Keywords:
References: None |
Problem Statement: How can I use kinetic and equilibrium reactions together in a RadFrac column? Can this be done by having the equilibrium reactions defined globally in Data\Reactions\Chemistry and the kinetic reactions defined as type REAC-DIST in the Data\Blocks\RadFrac\Reactions sheet? | Solution: For RadFrac columns, if you have a reactive system, you have to use either CHEMISTRY and / or the REAC-DIST type in the REACTIONS paragraph (Data\Blocks\Column\Reactions sheet).
REAC-DIST allows Kinetic, Equilibrium and Conversion reactions to be supplied, all in the same reaction set (e.g R-1) if required. For Kinetic reactions, REAC-DIST only allows power-law or user kinetics subroutines. LHHW is not available.
As for the equilibrium reactions, if they are not electrolyte reactions or salt precipitations, then use the REACTION paragraph, again REAC-DIST and choose Equilibrium as type. The Data\Reactions\Chemistry form is only used to define electrolyteSolution equilibrium for reactions involving the formation of ionic species. For each segment in the RadFrac column, only one of Reaction-ID or Chemistry-ID (electrolyte reactions) can be specified.
If you have a system with electrolytes, and using the APPARENT approach, then specify theSolution chemistry on the Data\Reactions\Chemistry form. If you do not specify a particular RadFrac stage to use this Chemistry-ID, then the chemistry will actually be calculated for the entire column and any other unit operations in the simulation. The chemistry will be taken into account throughout the entire flowsheet. However, if you specify a particular RadFrac segment (in Data\Blocks\Column\Reaction) to use the chemistry, then electrolyte chemistry will only be calculated in that section of the column. If using electrolytes with the TRUE approach, refer toSolution 3299: Using RadFrac with electrolytes, Chemistry & Reactions.
Note that the Data\Reactions\Reaction form works differently. If specified, by default there will be no reaction in any part of the flowsheet and column, for REACTIONS you always have to specify the RadFrac segment in which they occur.
Keywords: RadFrac
Chemistry
Reactions
References: None |
Problem Statement: There are 3 Absorber icons (ABSBR1, ABSBR2 and ABSBR3) for RadFrac that appear to be the same. What is the difference? | Solution: At one time, the 3 icons were different in the appearance on the Process Flow Diagram (PFD) or workspace. The icons had different feed locations for inlet streams. Now, all of the feeds are in the same location. Since the Icon information is saved in .bkp files, old bkp files upward compatibility will be an issue if we remove the duplicate icons.
The actual location of the feeds is set on the RadFrac\Setup\Streams sheet. It is important to remember that the input on the Data Browser forms determine the simulation process. The icons are only a visual aid to help depict the process. The different icons have no effect on the process. This means that an ABSRBx icon can be used even when a condenser and/or reboiler are specified for the column.
Keywords: radfrac
References: None |
Problem Statement: Which properties are required from a CAPE OPEN ThermoPackage when it is called from Aspen Plus? | Solution: The following properties may be required by Aspen Plus:
'fugacityCoefficient'
'fugacityCoefficient.Dtemperature'
'enthalpy'
'heatCapacity'
'entropy'
'entropy.Dtemperature'
'gibbsFreeEnergy'
'gibbsFreeEnergy.Dtemperature'
'volume'
'volume.Dtemperature'
Note that 'heatCapacity' is required instead of 'enthalpy.Dtemperature'
For example, a Flash2 block with liquid-vapor calculation mode and temperature and pressure specification will require the following properties:
fugacityCoefficient (CALCTYPE:Mixture, PHASE:Liquid)
enthalpy (CALCTYPE:Mixture, PHASE:Liquid)
entropy (CALCTYPE:Mixture, PHASE:Liquid)
volume (CALCTYPE:Mixture, PHASE:Liquid)
fugacityCoefficient (CALCTYPE:Mixture, PHASE:Vapor)
enthalpy (CALCTYPE:Mixture, PHASE:Vapor)
entropy (CALCTYPE:Mixture, PHASE:Vapor)
volume (CALCTYPE:Mixture, PHASE:Vapor)
For another example, a Flash2 block with pressure and duty specification, the following properties are required:
fugacityCoefficient (CALCTYPE:Mixture, PHASE:Vapor)
fugacityCoefficient.Dtemperature (CALCTYPE:Mixture, PHASE:Vapor) enthalpy (CALCTYPE:Mixture, PHASE:Vapor)
heatCapacity (CALCTYPE:Mixture, PHASE:Vapor)
entropy (CALCTYPE:Mixture, PHASE:Liquid)
volume (CALCTYPE:Mixture, PHASE:Liquid)
fugacityCoefficient (CALCTYPE:Mixture, PHASE:Liquid)
fugacityCoefficient.Dtemperature (CALCTYPE:Mixture, PHASE:Liquid) enthalpy (CALCTYPE:Mixture, PHASE:Liquid)
heatCapacity (CALCTYPE:Mixture, PHASE:Liquid)
entropy (CALCTYPE:Mixture, PHASE:Vapor)
volume (CALCTYPE:Mixture, PHASE:Vapor)
The temperature derivative of fugacity coefficients and enthalpy are part of the inside-out algorithm requirements used to adjust composition and temperature (depending on flash specifications). The entropy is calculated at the end of the flash to complete the stream information.
A Flash3 block with liquid-liquid-vapor calculation mode will require the same properties as the Flash2, as well as the gibbsFreeEnergy for the liquid mixture. The phase splitting algorithm depends on Gibbs free energy.
This can be extended to any block doing vapor-liquid and vapor-liquid-liquid calculations.
Keywords: CO
References: None |
Problem Statement: Unable to load the Excel Add-In to run the Calculator Block | Solution: If user is going to uninstall a previous version of Aspen Plus, it must be done BEFORE installing the new version otherwise there will be problems with the Excel Add-In.
If you do need to uninstall a previous version of Aspen Plus AFTER installing an newer version, you may need to re-install the newer version.
Keywords: Excel, Add-In
References: None |
Problem Statement: What is the source of costing estimating data in Aspen Plus input language? | Solution: All cost estimating featues of Aspen Plus have been superseded by ICARUS system, and are no longer support in the User Interface (GUI).
Aspen Plus equipment cost estimates are based on methods defined by PDQ$ Inc. The PDQ$ routines are integrated into the Aspen Plus Costing system to estimate the cost of both catalogue and fabricated equipment. PDQ$ is the default method (the other method being the user-specified power-law type correlation), and is based on actual vendor data.
PDQ$ equipment costs are updated by an appropriate cost index. PDQ$ issues a quarterly updatecost index; however, Aspen Plus does not update its costing system any more.
Aspen Plus Costing uses March 1993 cost index values.
Keywords: cos
References: None |
Problem Statement: What changes were made to the HEATX model's calculations between versions 10.2 and 11.1? | Solution: 1. Actual exchanger area will be provided in all output. In version 10.2, actual area was not shown in results when area was specified as input for shortcut method.
2. Actual area will always reflect the specified input area. If the detailed method is used and no area is specified, the area calculated from the geometry will be displayed. The previous version would show the area calculated from the geometry for all cases even though the specified area was used for the simulation.
In version 10.2, some users would specify an area that was some multiple of the bundle area (i.e. specify two - 2000 sq ft bundles in series as having an area of 4000). The version 11,1 report will always show the total area.
3. Percent overdesign will be provided in the results for all cases. The calculation method has been changed. The old and new formulas are as follows:
Old:
Overdesign % = (1 - ReqdArea/ActualArea) * 100
New:
Overdesign % = (ActualArea/ReqdArea - 1) * 100 (if oversurfaced)
Overdesign % = (1 - ReqdArea/ActualArea) * 100 (if undersurfaced)
4. For short cut HEATX models can use multiple shells in series. Change the flow direction to multi-pass on the specifications sheet and either specify the number of shells in series, or check the box to allow Aspen Plus to calculate the required number of shells in series. In version 11.1, the number of shells has been added to the results.
5. Single pass cocurrent flow exchangers will have different results due to a correction in the MTD calculation. The previous version was applying a correction factor to the LMTD.
6. Exchangers with multiple zones due to a phase change in the exchanger or due to a user's request for multiple film coefficient calculations, will have different results due the previous version improperly weighting the coefficients and LMTD for the individual zones. The following results will be different:
Average coefficient (Dirty)
Average coefficient (Clean)
LMTD (corrected)
7. For those exchangers with multipass shells (not TEMA type E shells), the following values will also change due to a different LMTD correction factor. The LMTD correction factor is dependent on the average heat transfer coefficient for the exchanger:
LMTD correction factor
Number of transfer units (NTU)
Thermal effectiveness (XI)
Heat duty (if in simulation mode)
Area required
Actual area (if in design mode) Changes to the values immediately above would be most significant for exchangers with phase change applications in which the heat release curves are very nonlinear.
8. The zone summary results were revised to show a corrected rather than an uncorrected LMTD and Area for each zone.
9. The fin efficiency calculation was corrected. The previous version was using an incorrect value in the fin efficiency formula. Most exchanger results would be impacted by this change.
10. Outlet stream conditions or intermediate conditions on a convergence loop may change due to a correction in the maximum heat load calculation. The program had calculated the maximum load during the first iteration. This maximum load was used in all subsequent iterations regardless if inlet flows, temperatures, pressures or stream composition changed.
11. Minimum temperature approach specification will now limit the heat load in simulation mode. Previous version merely warned that it was violated but proceeded with the simulation.
Keywords: None
References: None |
Problem Statement: For a water stream at 60 F and 1 atm which enters a flash block at 60 F and 1 atm, the water coming out of the block should also be at 60 F and 1 atm. The standard volume (STDVOL) for the inlet stream is 22.4 l/min, but the volume flow for the outlet stream is 22.29 l/min, why are they different?
Is this a problem with the report writer?
Here are the stream results when the flow was specified as 22.4 l/min Std Volume:
Substream: MIXED
Mass Flow KG/HR
N2 0
H2O 1341.415
Total Flow KMOL/HR 74.45983
Total Flow KG/HR 1341.415
Total Flow L/MIN 22.29951
Temperature K 288.7056
Pressure ATM 1
Vapor Frac 0
Density MOL/CC 0.0556513
Density GM/CC 1.002574
Average MW 18.01528
Liq Vol 60F L/MIN 22.4
If I switch the flow basis to VOLUME (from STDVOL), the standard volume goes up, but the flowing volume is OK.
Substream: MIXED
Mass Flow KG/HR
N2 0
H2O 1347.46
Total Flow KMOL/HR 74.79539
Total Flow KG/HR 1347.46
Total Flow L/MIN 22.4
Temperature K 288.7056
Pressure ATM 1
Vapor Frac 0
Density MOL/CC 0.0556513
Density GM/CC 1.002574
Average MW 18.01528
Liq Vol 60F L/MIN 22.50095 | Solution: When standard volume is specified for the feed flow rate, the standard liquid volume flow is converted to mass flow rate using the standard liquid volume. Standard liquid volume (defined at 60F, 1 atm) is calculated from the parameter VLSTD (Standard liquid molar volume of a pure component at 60 F) which is stored in our databank. This parameter can come from a variety of sources (API technical databook, or DIPPR databank--computed from the pure component density correlation at 60F). VLSTD is a constant value for each component.
The total volumetric flow reported in the Stream summary is computed differently. Since it has to be general (i.e., at any T and P of the stream), the conversion from mole or mass to liquid volume is done using the density calculated by the density model (e.g., Rackett or an equation of state, depending on the Property Method). Results from these models may not be the same as VLSTD when evaluated at 60F. This difference results in the discrepancy reported here.
To illustrate this point, there is a property route VLMX27 which calculates liquid molar volume of a mixture (VLMX) from VLSTD. If this route is substituted on the Property Method Routes form, the reported total volumetric flow is 22.4 l/min. Note that the density will be 0.99807645 gm/CC instead of 1.0025743 (using the Ideal method). Note that this route is temperature INDEPENDENT.
For the Rackett molar volume model, it is possible to constrain it to reproduce VLSTD (or specific gravity) by writing a user model or by regressing new values of the Racket model parameters (RKTZRA).
If you want to match the standard liquid volume exactly, but do not want to use VLMX27 which uses VLSTD to calculate it.
Options are:
Write your own user model. (This is not an easy task.)
Accept the non-temperature dependent VLMX27 route. (This is probably a bad option.)
Accept that VLSTD will not match VLMX exactly.
Regress API or RKTZRA to have the values match the VLSTD values. You can enter the one data point and use estimation with the method of Data for VL as a shortcut. (You probably will want to have an ideal mixing rule for VLMX (VLMX26))
Keywords: vlstd
vl
molar volume
rho
rhomx
density
References: None |
Problem Statement: Can I use a different databank for the same component in different parts of the Aspen Plus flowsheet? | Solution: This is not possible directly.
However, a workaround is to create two component names for the same component, and for the second component enter manually the pure component and VLE data in the Properties / Parameters / Pure Component and Binary Interaction forms. You could then use an RStoic block between different flowsheet sections to convert one version of the component to the other.
Keywords:
References: None |
Problem Statement: This is an application to strip acetoaldehyde from water. After calculation converged, the following error was given during report generation although result status indicated Result available:
*** Severe Error
Single Phase tenmperature calculations failed in 15 iterations. Final temperature is 145.0889. Final enthalpy is -8.0800D+07. Specified enthalpy is -7.1959D+07. | Solution: It doesn't seem serious error. But we should not ignore this message. This error message should not be ignored since it is due to a flash failure in one of the streams that is probably indicative of physical property problems. Looking at further the problem, it was found that too low gas feed temperature caused very low temperature at the column bottom(3-degC), which is close to water triple point and Aspen Plus gave an error. Using higher gas feed temperature(10 deg-C or above), this error was gone. Also, higher gas feed would give better performance for stripping based on Sensitivity study.
Keywords: Physical Properties, RADFRAC, Flash convergence
References: None |
Problem Statement: How can one simulate a column without a condenser and reboiler (e.g. an absorber) in Aspen Plus? | Solution: Use the RadFrac model and specify None for the condenser and the reboiler. No other columnn specifications are needed since no condenser sets the top stage duty to zero and no reboiler sets the bottom stage duty to zero. Do not try to specify zero reflux or zero boilup.
As RadFrac requires both vapor and liquid flows on each stage, you must provide a liquid feed stream to the top stage if there is no condenser, and a vapor feed stream to the bottom stage if there is no reboiler. To ensure that the vapor actually goes to the bottom stage the feed convention needs to be set to ON-STAGE on the Radfrac \ Setup \ Streams sheet.
If there are convergence difficulties the following hints can be helpful:
1. Select Absorber=Yes on the Radfrac \ Convergence \ Advanced sheet, which requires the use of the Standard algorithm.
2. Since absorber systems are inherently wide boiling, temperature estimates for the top and bottom stages should be provided to help convergence. It is best to underestimate the top stage and overestimate the bottom stage temperatures by a few degrees. Provide the estimates on the RadFrac \ Estimates \ Temperature sheet.
3. For very wide boiling systems, try specifying the Petroleum/Wide-Boiling Convergence method on the RadFrac \ Setup \ Basic sheet which uses the Sum-Rates algorithm.
4. To further help column initialize, provide stage composition estimates on the RadFrac \ Estimates form.
Keywords: radfrac
qn=0
q1=0
steam stripper
References: None |
Problem Statement: There was an error message in the control panel about PHIMX. How does one find the definition? Search retrieved nothing.
Cause
The problem is that PHIMX is in Aspen Physical Property System help. | Solution: Click on Aspen Physical Property System Help in the right hand pane and then search.
Detailed Explanation
When the property system help became shared between the Aspen Plus and Aspen Properties products, it was found to be impossible to integrate the contents properly. In particular, if the help contents file references a file it cannot find, or WinHelp finds a different version of the file which does not match the contents listing, then as best the help contents listing is cut off at the first missing topic, or at worst help crashes. (The crashing I think was fixed with the first upgrade of the RoboHelp library; I know I have not seen it since then.)
The main problem is that these help files are used by two products which live in different directories. When one help system links to a topic in a different help system (that is, with a different master contents file), the contents panel refreshes only partly. That is, it now follows along as you follow links in the new help system, but with the listing of topics from the old help system, meaning that something entirely unrelated is displayed in the panel at the left. Each help file is assigned to one master help contents file, so whichever one I chose to put them in, they would be broken when used from the other application.
This was resolved by completely separating the shared help and putting it into the APrSystem folder as a third completely separate help system. Additionally, all links from one help system to another were designed so that they launched a new copy of WinHelp open to the desired topic; this allowed the help contents to refresh. In order for this to work, this must be the only way of navigating from one help system to another. The index and search cannot include topics from another help system.
This has a small side-effect: When linking to another help system in another folder, WinHelp depends on a section of the registry to find the help files, and in this section there is only one path possible for each help file name. Since Aspen Plus and Properties are not equipped to handle versioned help file names (changing the help file names from say apwn121 to apwn131 to apwn132 for each new version), such links will always go to the latest registered version of the help. This is a minor defect for users who install and use multiple versions of these products concurrently on one computer, but otherwise not a problem.
Enhancements
Text was added to the three help systems to make it more clear to users that these separate help systems exist. But we should do more.
Another small step was to add links to the Help menu in Aspen Plus and Aspen Properties to explicitly call the APrSystem help. These should appear just below the item Help Topics.
This integrated contents/index/search panel where all the chaos occurs is generated by a library supplied with RoboHelp. Native WinHelp brings this up in a separate window only when you ask for it. While it does not have this half-refreshing bug, it doesn't appear at all except when you click the contents button to specifically jump to another topic through the contents, and after you do so or cancel, the window goes away. Additionally, it does not follow along as you click links or navigate via the index or search, so users don't see the context of where their current topic is in the large help system. I think nobody wants to go back to that.
One other idea is to just include the help topics for the APrSystem help files in the master contents files used by Aspen Plus and Aspen Properties. This would require installing all help files in the same folder (the APrSystem folder would have to be the one). Until we have time to make this major change in how help is delivered, this option has been deferred.
Keywords: hhelp
References: None |
Problem Statement: In some simulations which involve electrolytes, the following warnings are printed to the Aspen Plus Control Panel:
WARNING IN PHYSICAL PROPERTY SYSTEM ATTEMPT TO USE MODEL ELECNRTL WITHOUT A SOLVENT. ACTIVITY COEFFICIENT OF UNITY IS USED
WARNING IN PHYSICAL PROPERTY SYSTEM WHILE PERFORMING INITIAL ENTHALPY CALCULATIONS FOR STREAM: 1 ATTEMPT TO CALCULATE ENTHALPY FOR ELECNRTL MODEL WITHOUT A SOLVENT.
What is the cause of these warnings and what can be done to resolve them? | Solution: ELECNRTL is applicable to systems containing electrolytes. i.e., aqueous systems. Water is required to define the standard state of the ions and possibly also the standard state of the molecular solutes (e.g., Henry components). Whenever you try to apply the model to a system which is free of water, the above warnings are issued.
Usually, this happens with non-aqueous feed streams, or streams from which water has been removed by the up-stream block. This is not necessarily wrong. Common situations include gaseous (feed) streams to which the ELECNRTL activity coefficient model is not applied at all. You should, however, carefully read through the warning messages and make sure they only concern streams for which you did not intend to use ELECNRTL.
Note: For single-phase feed streams (vapor-only or solid-only), you can often eliminate the warning by changing the valid phases on the Stream Input Flash Options Sheet accordingly. For anyhdrous solid or pure vapor streams that are truly dry, changing the phases is valid.
However, some of these streams could have some small amount of water in them. Then, you may want to add a few ppm of water to the stream. This will eliminate the warning and improve the accuracy of the simulation.
Keywords:
References: None |
Problem Statement: How is it possible to model a Plug Flow Reactor with RPLUG and adjust for less than perfect radial mixing? | Solution: This is similar to adjusting the efficiency of the RPLUG model. To adjust the efficiency of the reactions in an RPLUG block simply add a bypass around RPLUG. With this model a Design Spec or Sensitivity Analysis can now be added to match plant data.
See attached example.
Keywords: reaction
efficiency
References: None |
Problem Statement: Unable to start License Manager. If running under Windows NT, there will be an NT Event log entry. If running under Windows 9x, there will be no error messages. | Solution: The cause could be that the clock inside the SuperPro dongle and the PC clock differ by more than 4 hours. This occurs most commonly when the customer has performed Year 2000 testing and attempts to run the License Manager after resetting the PC clock.
Log file entry
00-Jan-07 14:31:23: Loaded key C:\PROGRA~1\ASPENT~1\LICENS~1.0\10.lic (aspen) 1 tokens starts Oct 12 00:00:00 1999, expires Jul 15 23:59:59 2000 [MINIKEY]. 00-Jan-07 14:31:23: aspen (10): check_dongle: bad dongle date. 00-Jan-07 14:31:54: System clock set back; contact AspenTech for help. ASPLMD.EXE Terminated.Solution
Open a License Manager Admin window and enter the command asplmadm -T. This will check the PC clock against the dongle clock. If they disagree, the utility will return a server code. E-Mail this code to [email protected] or call the hotline. Explaine the problem and request a reset Key.
After getting a new Code from Support, Open a License Manager Admin window and enter the command asplmadm -T. Ente the Code, and keep in mind that the Code you have received is only valid for approximately 4 hours. Restart the License Manager after entering the code..
Keywords:
References: None |
Problem Statement: Can the Cavitation Index for a valve be calculated in Aspen Plus? | Solution: The likelihood of cavitation is measured by the cavitation index. The cavitation index can be calculated in the VALVE model to predict cavitation in a chamber or other system.
Cavitation index for the specified inlet stream conditions is calculated if the Calculate Cavitation Index box on the Valve \ Input \ Calculation Options sheet is checked and the inlet stream is all liquid. This option is available for valve design and rating calculations, but not for simple pressure change.
AspenÂPlus calculates the cavitation index as (Flow Equations for Sizing Control Valves, ISA-S75.01-1985, Instrument Society of America, 1985):
Kc = [ ( Pin - Pout ) / ( Pin - Pv ) ]
Where:
Kc = Cavitation index
Pin = Inlet pressure
Pout = Outlet pressure
Pv = Vapor pressure at inlet
The cavitation index definition is valid only for all-liquid streams. Valve calculates the cavitation index if you check the Calculate Cavitation Index box on the Input CalculationOptions sheet.
Keywords:
References: None |
Problem Statement: When using the Wilson-LR (or Wilson-GLR with Liquid as reference state) the vapor phase Cp is exactly equal to the values reported by other property methods such as Ideal or NRTL. Why is that since the calculation route must be different (at least they do not have the same reference state)? | Solution: Attached are details about vapor-phase Cp calculation for the Wilson-LR property methods, compared to the Ideal or NRTL property methods.
For mixture vapor-phase enthalpy (HVMX) calculations, results differ for the vapor phase enthalpy with the Wilson-LR property methods which is using the saturated liquid as reference state. However, as reported, all the Cp's for the vapor phase are exactly the same, regardless of the property methods.
With the Wilson-LR property methods, the HVMX calculation route is the same as with the other property methods (HVMX00). However, the saturated liquid being taken as reference, vapor phase enthalpy is calculated from the liquid phase enthalpy.
For the Ideal, NRTL and Wilson-GLR (ref. state = gas @ 25C) property methods, the calculation for the Cp is obvious: the DIPPR liquid heat capacity model is used to calculate the vapor-phase Cp's. This is true only if DIPPR Liquid Heat capacity coefficients are available for all components.
For the Wilson-LR property method, if we follow the calculation route which is described page 3-121 of the Aspen Plus 10.1 manual 'Physical Property end Methods Models' and take the derivative with respect to temperature of the vapor phase enthalpy, we end-up with the vapor-phase Cp being equal to the Ideal gas heat capacity (see details in the attached Word file).
The Ideal gas Cp is then calculated with the DIPPR Liquid Heat Capacity model. This explains why we find the exact same value for the vapor phase Cp for all the property methods listed above.
Attachments
Detailed calculations of the vapor-phase Cp for the Wilson-LR property method are in the attached Word file.
Keywords: heat capacity, WILS-LR, WILS-GLR
References: None |
Problem Statement: How can parallel, series and mixed reactions be modeled using RStoic? | Solution: In PARALLEL (or COMPETING), reactions, one reactant forms multiple products through separate reactions, e.g.:
A ---> B
A ---> C
In SERIES (or CONSECUTIVE) reactions, a reactant is consumed to form an intermediate product, which then reacts again to form the final product, e.g.,
A ---> B ---> C
In mixed reaction systems, both series and parallel reactions occur, e.g.:
A
--->
B + C
A
--->
D + E
B +
D
--->
F + G
All of the above reaction systems can be simulated using the RStoic reactor block in Aspen Plus.
In all the following cases the reaction conversion or extent must be specified for each reaction.
PARALLEL REACTIONS Parallel reactions are modeled by not checking the Reactions occur in series box on the RStoic Setup / Reactions sheet in Aspen Plus 10 or by setting 'SERIES = NO' on the RSTOIC.Main form in Aspen Plus 9. This option is the default.
It is important to note that if a component, which appears as a reactant in some reaction(s), is not present in the feed, the reaction(s) will be dropped, even if the component is produced in some other reaction(s).
e.g. For parallel reactions
A + B
--->
C
(1)
A + C
--->
D
(2)
if component C is not present in the feed, reaction (2) will be dropped and Aspen Plus will issue a warning. The final amount of C will then simply be the amount produced in reaction (1).
SERIES REACTIONS Series reactions are simulated by checking the Reactions occur in series box on the RStoic Setup / Reactions sheet in Aspen Plus 10 or by setting 'SERIES = YES' on the RSTOIC.Main form in Aspen Plus 9.
The numerical order in which the reactions are entered determines the order in which the reactions take place. If a component, which appears as a reactant in some reaction(s), is consumed in preceding reaction(s) in the series, Aspen Plus will set the conversion/extent of the later reaction(s) to zero, meaning that the later reaction(s) will not proceed.
e.g. For series reactions
A + B ---> C (1)
A + C ---> D (2),
if component A is consumed in the first reaction, ASPEN PLUS will issue a warning, stating that the flowrate of A is zero, and therefore that the conversion/extent of reaction (2) has been set to zero. As a result, reaction (2) will not take place.
MIXED REACTIONS Mixed reactions can be modeled sing two separate RStoic blocks, one for the parallel and one for the series reactions. Alternatively, the whole system can be modeled as one RStoic reactor, with the Reactions occur in series box checked or 'SERIES = YES', but it is essential that the order of the reactions is correctly specified.
e.g. For mixed reactions
D + E ---> F + A (1)
A ---> B (2)
A ---> C (3)
assume that the last two reactions occur in parallel. We can then model the system using two RStoic blocks:
RStoic 1
--------
D + E ---> F + A
RStoic 2
--------
A ---> B
A ---> C
If we modeled the system as one RStoic block, with
the Reactions occur in series box checked or
'SERIES = YES' the results would be different that the two
BLOCK approach HOWEVER, the numerical order of the reactions
will determine the results (i.e. 1,2,3); If, for example, we specified the order as
A ---> B (1)
D + E ---> F + A (2)
A ---> C (3)
the results would be different than the following order:
D + E ---> F + A (2)
A ---> B (1)
A ---> C (3)
because each reaction is considered separately in the order specified.
The specified conversions have been omitted from the examples for simplicity.
Keywords:
References: None |
Problem Statement: How can I check the valid temperature, pressure and composition range of built-in binary parameters? | Solution: To verify the ranges of built-in binary parameters for activity coefficient models complete the following steps:
1. Go to the Properties \ Parameters \ Binary Interaction forms in the Data Browser. The object manager for all binary parameters appears.
2. Double click on the name of the parameters that you want to check (for example NRTL-1, UNIQ-1, or WILSON-1 - don't worry about the '-1' right now). The binary parameter form appears.
3. When using Legacy databanks, go to a field with a binary parameter value and click on the Help button or push the F1 key. Aspen Plus displays the temperature, pressure and composition range where the parameters were regressed.
-or-
When using the Aspen Properties Enterprise Database, select a column of data on the sheet and click the Reg Info button to see the statistics for that pair.
Information about the number of data points used in the regression and the quality of the fit are displayed also. The range is determined by the experimental data. The simulation is not limited to this range; however, activity coefficient binary interaction parameters do not always extrapolate well with temperature.
Below is an example of the information displayed:
This information is not available for every Binary databank. Parameters that have been obtained from literature or which were regressed before version 9 do not have validity range information. Parameters from literature in the VLE-LIT and LLE-LIT databanks were obtained from the DECHEMA Chemistry Data Series.
Binary Databanks that contain regression information are:
NRTL: VLE-IG, VLE-RK, VLE-HOC, LLE-ASPEN
UNIQ: VLE-IG, VLE-IG, VLE-HOC, LLE-ASPEN
WILSON: VLE-IG, VLE-IG, VLE-HOC
HENRY: HENRY
It is important to check this information to determine if the parameters apply to the conditions used in the flowsheet. The results of a simulation using conditions outside of the regression range should be reviewed thoroughly.
Keywords: binary databank
reference
References: None |
Problem Statement: How to include IF…THEN statement in a Fortran Calculator block so Aspen Plus can interpret it. | Solution: The example attached illustrates the use of IF…THEN statement in a Fortran Calculator block so Aspen Plus can interpret it.
Taking into account the configuration above, the aim of the Calculator block is to adjust the amount of water coming into the Heater (COOLW mass-flow), so the outlet stream temperature is 10 degrees higher than the inlet. The COOLW flow is calculated as follows:
COOLW = DUTY/(CPMX*10)
where DUTY represents the heat coming into the Heater block and CPMX the COOLW stream mixture heat capacity.
Heat stream can be zero if there is no vapor coming out from the FLASH block, stream A flow will be zero. In this situation the COOLWOUT flow will be then zero and in a larger simulation, where this stream would go into another block, this might lead into some problems downstream.
To avoid this, IF statement is included in the calculator block. The condition to be satisfied is DUTY equal to zero, in which case a very small flow of COOLW is set so no warning appears in the Heater block. Otherwise, the flow is calculated according to the equation above defined.
Keywords: IF, THEN, fortran, calculator block
References: None |
Problem Statement: RadFrac has a simple thermosyphon reboiler. How do you simulate a rigorous thermosyphon model coupled to RadFrac? | Solution: To obtain thermosyphon reboiler process feed stream data from RadFrac:
1. Start by connecting a new stream to the pseudo stream connection port on the RadFrac block in the flowsheet view. The pseudo stream connection port is typically located on the right side, towards the center of the RadFrac icon.
2. Hit the next button or manually navigate to the RadFrac | Report form.
3. Visit the Pseudo Stream sheet on the Report form and define the new pseudo stream as the Inlet to the Reboiler for the Thermosyphon Reboiler stream, towards the center of the sheet.
The flow and conditions in the thermosyphon shown on Results Summary | Reboiler sheet will match that in the pseudo stream.
Notes:
The pseudo stream is not accounted for in the source unit's mass or energy balance. In this case, the Sum of the Feed streams equals the sum of the non-pseudo Product streams for the RadFrac column. However, the pseudo stream is part of the mass balance for any unit that is connected to the downstream side of the pseudo stream.
ThisSolution works for the PetroFrac column as well.
Keywords: RADFRAC, thermosiphon, thermosyphon, PETROFRAC, pseudo stream
References: None |
Problem Statement: The diagram Variable Explorer.bmp shows the Variable Explorer tree for the RYIELD reactor block B1 in the RYIELD.bkp simulation. In the RYEILD reactor model, the specified yield for each component are held in the input variable MOLE_YIELD:
Application.Tree.Data.Blocks.CHARSPLT.Input.MOLE_YIELD.(CHAR,NC)
The yield node is an example of a node which uses paired scrolling of identifiers; component (CHAR) and substream (NC). How can I access one of the specified yield fractions via a Visual Basic Interface? | Solution: Below is the VB code to access an Aspen Variable that has a paired identifier. In this example, we access the specified yield in RYIELD block B1 for non-conventional component CHAR:
Dim go_simulation As IHapp
Dim ihCHAR As IHNode
Dim Yield As Double
Set go_simulation = GetObject(~:\insert file path here\RYIELD.bkp)
Set ihCHAR = go_simulation.Tree.Data.Blocks.B1.Input.MOLE_YIELD
Yield = ihCHAR.Elements(CHAR, NC).Value
Alternatively, you can pass either a pair of integers or a pair of strings as arguments. To use a string argument:
Set ihCHAR = go_simulation.Tree.Data.Blocks.B1.Input.MOLE_YIELD
ls_dummy3 = NC
ls_dummy2 = CHAR
ihCHAR.Elements(ls_dummy2, ls_dummy3).Value = 0.48
Instead of using a string argument, you can also specify an argument for the component dimension of the collection. In the case of the reactor yield, the node MOLE_YEILD has two dimensions; component (dim = 0) and substream (dim = 1), and each dimension has 2 locations (component1 and component2). If you look in the variable explorer, under MOLE_YIELD you have the following paired offspring nodes:
Application.Tree.Data.Blocks.CHARSPLT.Input.MOLE_YIELD......
- (CHAR, NC)
- (SLD2GAS, NC)
For the component dimension (dim = 0), location 0 = component CHAR and location 1 = component SLD2GAS. Where as for the substream dimension (dim = 1), location 0 = NC and location 1 = NC. Therefore to access ELEMENT.(CHAR, NC), use ELEMENT.ITEM.(dimension, location) instead.
Set go_simulation = GetObject(D:\Data\Incidents\Parsons Projects\333217\RYIELD.bkp)
Set ihCHAR = go_simulation.Tree.Data.Blocks.B1.Input.MOLE_YIELD
ls_dummy1 = 0 ' dimension = component
ls_dummy2 = 0 ' location 0 = Char , location 1 = SLD2GAS
ihCHAR.Elements.Item(ls_dummy1, ls_dummy2).Value = 0.48
Keywords: VBA
reactor yield
RYield
paired identifiers
References: None |
Problem Statement: What is a Production Allocation Utility and how do I use it? Is there a known issue with the Utility? | Solution: The Production Allocation Utility enables you to track the contribution of selected streams to other down flowsheet streams. The contribution is tracked on a compositional flow or percentage basis. Use of the Production Allocation Utility is particularly relevant in scenarios where a model depicts a system that relies on multiple suppliers for inlet feeds and the user wants to track the individual supplier contributions to the resulting products.
Production Allocation Utility is added from Tools | Utility | Select Production Allocation Utility | Click Add Utility.
Note: Aspen Hysys_Upsteam license is required to run Production Allocation Utility.
Example: Three feed streams A, B and C are inlet to the MIX 100. The contribution of feed streams A, B and C can be viewed in the product streams C2+Product and 20 using the production allocation utility. The steps to create Production Allocation Utility are:
1. Add Production Allocation Utility from the Tools | Utility menu.
2. Select feed stream A, B, and C on the setup TAB
3. On the results TAB select the product stream you want to see the contributions of the feed streams.
Known Issues:
1. Production Allocation Utility is not designed to work with Black Oil models as there is not much advantage.
2. Black Oil translator is used to translate the information in the composition term, then the Production Allocation Utility can be used.
3. It works with Lumper, in version 3.4/2004/2004./ 2004.2
4. It does not work in version 2006 with Lumpers but again works from version 2006.5.
Keywords: None
References: None |
Problem Statement: How to I set up an enthalpy / pressure diagram for a HF / H2O system? | Solution: First, create a simulation with H2O / HF as components and use the electrolyte wizard to generate the electrolytic components and chemistry. The enthalpy / pressure diagram can be easily created using a Generic type of Analysis available from the Properties Analysis forms. The run mode can optionally be changed from Flowsheet to Property Analysis to only create a property analysis table and not run the flowsheet simulation.
The steps required are:
Create a prop-set (Data Browser/Properties/Prop-Sets) that contains the property HMX (Enthalpy of a mixture).
From the Data\Properties\Analysis form create a new Analysis object of type Generic.
On the System sheet, specify to generate points along a flash curve. Also, define the system composition.
On the Variable sheet, add both Pressure and Vapor Fraction to the Adjusted varaible table. Also, click on the Range/List button and define the range of values over which these variables should be varied.
On the Tabulate sheet, select the name of the Prop-Set with the HMX property.
Change the Property Method on the Properties sheet if needed.
Run and review the results in the Analysis object. While looking in the Analysis Results form, generate a plot from the plot menu by making the pressure the x variable, the vapor fraction the parametric variable and the enthalpy the y variable.
Keywords: property analysis, HF, enthalpy presure diagram
References: None |
Problem Statement: How do I reference a RadFrac internal design specification target value for use in a Sensitivity block, or a Calculator block? | Solution: When you define the variable accessing the design specification target, choose the
Keywords:
References: Type Block-Var followed by the block name, followed by the Variable VALUE.
VALUE here is defined in the text at the bottom of the window as Desired Value of Design Specification specified variable, in SI Units.
Next you need to fill the field ID1, which is described as Design specification number (1 for 1st Spec in this block, etc...). |
Problem Statement: How can I find if binary parameters are provided in Aspen Plus or Aspen Properties binary databank for a specific component with any other component available in databanks for activity coefficient models such as NRTL or UNIQUAC? This is useful since binary interaction parameters are critical for correct equilibrium predictions when using activity coefficient models. | Solution: In AES 11.1 and higher, there is a file called binary parameters for gamma models.xls in the APrSystem xxxx\GUI\xeq directory. In this file, you can search the list of component pairs available in the VLE-IG, VLE-RK and VLE-HOC databanks. Details about what is included in this file is given below. The Aspen Properties Database Manager provided in version 2006 also has search capabilities that can be used.
It is also possible to enter the components in the graphical interface and check in the binary parameter form if any parameters are retrieved, but this may be more time consuming and is not as exhaustive as a search in the spreadsheet.
Documentation for Binary Parameters for Gamma Models Spreadsheet
List of component pairs available in the VLE-IG, VLE-RK and VLE-HOC databanks.
These databanks contain binary parameters for the Wilson, NRTL, and UNIQUAC models. Three equation of state models are used: ideal gas, Redlich-Kwong and Hayden-O'Connell. The binary parameters were obtained from regression of binary VLE data obtained from the Dortmund Data Bank (DDB). To the extent possible, only thermodynamically consistent data are used.
The nine sets of binary parameters are stored in the three databanks for the following option sets:
Databank: VLE-IG
Option set
Liquid model
Vapor EOS model
WILSON
Wilson
Ideal gas
NRTL
NRTL
Ideal gas
UNIQUAC
UNIQUAC
Ideal gas
Databank: VLE-RK
Option set
Liquid model
Vapor EOS model
WILS-RK
Wilson
Redlich-Kwong
NRTL-RK
NRTL
Redlich-Kwong
UNIQ-RK
UNIQUAC
Redlich-Kwong
Databank: VLE-HOC
Option set
Liquid model
Vapor EOS model
WILS-HOC
Wilson
Hayden-O'Connell
NRTL-HOC
NRTL
Hayden-O'Connell
UNIQ-HOC
UNIQUAC
Hayden-O'Connell
In the table, a dash (-) indicates that the binary parameters are not available for the option set. An x indicates that the binary parameters are available. In the Wils column, the three - and x symbols are for WILSON, WILS-RK and WILS-HOC option sets. In the NRTL column, the three - and x symbols are for NRTL, NRTL-RK and NRTL-HOC option sets. In the UNIQ column, the three - and x symbols are for UNIQUAC, UNIQ-RK and UNIQ-HOC option sets. System ID is for AspenTech internal reference.
Keywords: binary databank
parameter availability
References: None |
Problem Statement: I'm using a Chemistry set and a Reaction set in a RadFrac column or kinetic reactor. They are set up as equilibrium reactions and have the same specifications and same basis, but they are giving different results. Why is that happening? | Solution: Chemistry always uses Activity for calculations, so is only differentiated between using mole fraction or molality when calculating activity (multiplying basis by gamma). Thus, basis for Chemistry was called Molality or Mole fraction.
For Reactions, additional bases were added for it, such as Mole fraction (instead of activity). Therefore, the bases that actually used activity were named Mole gamma and Molal gamma
If you want to get the same results using Chemistry and Reactions, you would need to use Mole fraction or Molality in your Chemistry, and Mole Gamma or Molal Gamma in your Reaction.
Keywords: Chemistry, Reaction, mole fraction, mole gamma, basis
References: None |
Problem Statement: When the user clicks on a stream in the flowsheet view and then rigfht clicks, there is no longer an ANALYSIS option. This feature used to generate property analysis for just the currently highlighted stream. | Solution: In version 10.1 and in earlier versions of Aspen Plus, this feature was attached to the stream object. In version 10.2 and later, this feature is only accessible from the Tools menu.
First, highlight the stream by clicking the left mouse button on it in the flowsheet view. From the TOOLS menu select Analysis. On the next sub-menu, select STREAMS, and you will see all the Stream Property Analysis options for that stream.
SeeSolution 103758 for more information about Stream Analysis.
Keywords: Stream, analysis, Property Analysis
References: None |
Problem Statement: Customer is unable to access the License Manager, either through a Point | Solution: or using the asplmadm command.
Solution
The network does not have proper TCP name reSolution in place. The customer can use one of the following techniques to establish TCP name reSolution
DNS Server
WINS Server, for Windows Only environments
LMHOSTS File, for Windows Only Environments
Local HOSTS file
Test the TCP name reSolution using the ping command. You must be able to ping the Client PC host name from the License Manager Server and the License Manager Server host name from the Client PC.
Keywords:
References: None |
Problem Statement: How is the Equation Orientated (EO) Input form used? Are these values used in the Sequential Modular (SM) simulation? | Solution: The Equation Orientated (EO) Input form is used to assign values to constant variables. For example, if a Spec Group is used to change the specification of variables, then the newly assigned Constant variable is given a value using the EO input form.
If the simulation is run again in Sequential Modular (SM) mode, and the EO input form is not cleared before switching back to EO mode, then those variables specified on the EO input form will not have the SMSolution. Those variables will have the values as specified on the EO Input form.
Similarly, if the Spec-Group was not disabled, then those variables will be synchronized with the specifications as defined by the Spec-Group and not the SMSolution.
If switching back and forth between SM and EO mode, the EO input form should be cleared before each new synchronization. Similarly, any Spec Groups should be disabled too. This will prevent differences in variable values and specifications.
Keywords: Spec Group
EO input
EO mode
References: None |
Problem Statement: How is the rate of reaction interpreted? | Solution: The rate of reaction is not associated with a single species. The rate calculated from the pre-exponential factor (k0), activation energy (Ea), composition dependence, etcetera, is multiplied by the stoichiometric coefficient for any species, so that:
Rate of Reaction = r
For example, in the reaction:
2A + B --> C
The rate of reaction of A = -2r
the rate of reaction of B = -r
and the rate of reaction of C = r
The units of r are:
kgmoles
(sec- cubic meters)
Keywords:
References: None |
Problem Statement: What is the definition of the shell side maximum cross flow velocity as reported in the HeatX heat exchanger? | Solution: The shell side maximum cross flow velocity is as follows.
HeatX:
Shellside maximum crossflow velocity = total shellside stream mass flow / crosssection area / two-phase homogenous density
For segmental baffle cut, the cross sectional area is the cross section area near the shell centerline.
For rod baffle cut, the cross sectional area is the baffle flow area.
TASC:
The first question to ask about an area for flow over tubes is whether it is based on minimum gap (between the tubes), or whether it is superficial (as if there were no tubes present). The next question for tube bundles in a circular shell, is whether it is based on an crossflow area at the shell diameter, or at the baffle cut, or at some mean representative cross-section. The other dimension defining the crossflow area will be the baffle spacing.
In TASC, there is a local shellside flow model, which distinguishes between crossflow and other flows, such as leakages and bypass around the bundle etc. It also defines an area associated with each of these flows.
For output purposes, TASC uses a simplified definition of crossflow velocity, based on the total shellside flow, divided by the sum of the flow areas associated with the crossflow fraction, the bundle bypass and in-line pass partition flows. This is then divided by the minimum homogenous density. The area associated with the crossflow fraction depends on the detail of the shellside model, but typically will be somewhere between the values at the baffle cut and the shell centreline, and based on minimum gap.
In the explanation above, it is assumed that the exchanger has baffled cross flow, and that the end spaces are, as normal, significantly longer than the baffle spaces. For X or K shells, and for unbaffled exchangers, the description would be different.
Shellside velocity is particularly complicated, and given that there are a range of possible definitions, it is not surprising if two programs differ.
Keywords:
References: None |
Problem Statement: Where can I find critically evaluated physical property data sources and non-evaluated sources? | Solution: Some sources of phyisical property data are listed below.
Pure Component Property Sources
Critically Evaluated Data Sources
Editors have reviewed all sources and selected the data reported after testing and comparative analyses. (See below for electronic availability of data)
Chase, M. et al., in JANAF Thermochemical Tables, 2nd ed., NSRDS-NBS 37, National Bureau of Standards, Washington, D.C. (1971); supplements in J. Phys. Chem. Ref. Data 3, 311 (1974); 4, 1 (1975); 7, 793 (1978); 11, 695 (1982). (The 1982 volume is titled The NBS tables of chemical thermodynamic properties - Selected values for inorganic anc C1 and C2 organic substances in SI units by Wagman et al.)
Daubert, T.E. and R.P. Danner, DIPPR Data Compilation, American Institute of Chemical Engineers, New York. (Loose leaf sheets, and electronic distribution via NIST; extant). (*** This is the source of the PureXX databanks of ASPEN PLUS.)
Simmrock, K.H., R. Janowski, and A. Ohnsorge, Critical Data of Pure Substances, DECHEMA Data Series, Germany.
Thermodynamic Research Center, Selected Values of Properties of Chemical Compounds, Texas A&M University, College Station, Texas (loose leaf data sheets, extant 1980).
Generally Reliable Sources of Pure Component Data Editors have compiled the data collection, but have not attempted a selective process or data qualification. However, the editors have selected reliable authors or sources.
Boublik, T., V. Fried, and E. Hala, The Vapor Pressure of Pure Substances, Elsevier, New York (1973).
Encyclopedia of Polymer Science and Engineering, Vol. 1, 2nd Ed., Wiley-Interscience, New York (1985).
ESDU Validated Engineering Data Index, ESDU International, Ltd., London (1984).
Zemaitis, J., D. Clark, M. Rafal, and N. Scrivner, Handbook of Aqueous Electrolyte Thermodynamics, AIChE DIPPR (1986)
Non-Evaluated Sources of Pure Component Data
Dean, J.A., Ed. Lange's Handbook of Chemistry, 13th ed., McGraw-Hill, New York (1985).
Green, D.W., Ed. Perry's Chemical Engineer's Handbook, 6th ed., McGraw-Hill, New York (1984).
Reid, R.C., J.M. Prausnitz, and T.K. Sherwood, The Properties of Gases and Liquids, 3rd ed., McGraw-Hill, New York (1977). (*** Source of the ASPENPCD)
Reid, R.C., J.M. Prausnitz, and B.E. Poling, The Properties of Gases and Liquids, 4th ed., McGraw-Hill, New York (1987).
Vargaftik, N.B., Handbook of Thermophysical Properties of Gases and Liquids, 2nd ed., Halsted Press, New York (1975).
Weast, R.C. Ed., CRC Handbook of Chemistry and Physics, 64th ed., CRC Press, Boca Raton, Fla. (1983).
Wendholz, M. Ed., The Merck Index, An Encyclopedia of Chemicals, Drugs, and Biologicals, annual eds., Merck & Co., Rahway, N.J. (1983).
On-line Sources of Pure Component Data
DIALOG Information Services, Inc. (Knight-Ridder (800)334-2564).
STN International} (CAS (800) 848-6533): provides direct access to approximately 160 scientific and technical databases:
BEILSTEIN - Beilstein Institute for Organic Chemistry) with 4.9 million records
CASREACT - (CAS) with 1.1 million single step and 1.7 million multi-step reactions
DIPPR with 1,500 records (already discussed)
Technical Databases Services, Inc. (TDS) (212) 245-0044. Available databases:
TRC Thermophysical Property Datafile - Vapor Pressure
DIPPR Pure Component Databank
Sources for Mixture Data
There are no critically evaluated sources of mixture data; however, the DECHEMA collection does use some thermodynamic consistency tests to confirm binary data.
Literature Sources of Mixture Data
Christensen, C., J. Gmehling, P. Rasmussen, U. Weidlich, Heats of Mixing Data Collection, DECHEMA Chemistry Data Series, Germany. Available in the U.S. from Shcolium International Inc. (516)767-7171 P.O. Box 1519 Port Washington, NY 11050.
Engels, H., Phase Equilibria and Enthalpies of ElectrolyteSolutions, DECHEMA Chemistry Data Series, Germany.
Figurski, G., Vapor-Liquid Equilibrium Data for ElectrolyteSolutions, DECHEMA Chemistry Data Series, Germany.
Gmehling, J., V. Onken, V. Artl, Vapor-Liquid Equilibrium Data Collection, DECHEMA Chemistry Data Series, Germany:
VLE data and Antoine constants
activity coefficient parameters for Margules, Van Laar, Wilson, NRTL, and UNIQUAC models
Systems include: aqueous organic; organic hydroxy (alcohols, phenols, etc.); aldehyde, ketone, and ethers; carboxylic acids, anhydrides, and esters; aliphatic hydrocarbons; and aromatic hydrocarbons.
Knapp, H., R. Doring, et al., Vapor-Liquid Equilibrium for Mixtures of Low Boiling Substances}, DECHEMA Chemistry Data Series, Germany.
Knapp, H., M. Teller, and R. Langhorst, Solid-Liquid Equilibrium Data Collection, DECHEMA Chemistry Data Series, Germany.
Sorensen, J.M., and W. Arlt, Liquid-Liquid Equilibrium Data Collection, DECHEMA Chemistry Data Series, Germany.
Tiegs, D., J. Gmehling, et al., Activity Coefficients at Infinite Dilution, DECHEMA Chemistry Data Series, Germany.
Thermodynamic Research Center, Selected Values of Properties of Chemical Compounds, Texas A&M University, College Station, Texas (loose leaf data sheets, extant 1980).
DIPPR, Binary VLE Data File (limited in scope since it covers only 67 binary systems), (July 1993).
Zemaitis, J., D. Clark, M. Rafal, and N. Scrivner, Handbook of Aqueous Electrolyte Thermodynamics, AIChE DIPPR (1986)
On-line Sources of Mixture Data
Dortmund Databank - A superset of the DECHEMA data collection including:
Vapor-Liquid Equilibrium Data (VLE)
Liquid-Liquid Equilibrium Data (LLE)
Excess Enthalpy Data (HE)
Activity Coefficient at Infinite Dilution Data (ACT)
Gas-Liquid Equilibrium Data (GLE)
Excess Heat Capacity Data (CPE)
The Dortmund databank is available in the following electronic forms: Technical Data Services, DDBSP - from Prof. J. Gmehling, and Aspen Technology in a full version and a subset (containing the VLE, LLE, HE, and ACT databanks). (*** The Dortmund databank is the source of VLE, LLE, and GLE data used for the built-in binary parameters available in Release 9 and higher).
Technical Database Services (212) 245-0384. The service offers access to the following data:
Log P-Partition Coefficient Data including Octanol/Water
TRC Mixture data
Dortmund Databank (DDB)
Keywords: None
References: None |
Problem Statement: How does one model the pressure drop calculations involving piping joining at a T? | Solution: A MIXER block is needed to model a T. The outlet pressure is specified (not calculated) in the MIXER.
In order to determine the pressure drop, it is possible to use a Calculator block. The Calculator block can be used to solve for the final system pressure using the Bernoulli Equation and then write that value to the MIXER block.
The PIPE block also has straight and branched T's as fittings. Any number or combination can be selected. In addition, you can specify a Miscellaneous L/D for the calculations.
Pipe assumes that the pressure drop due to valves and fittings is distributed evenly along the specified length of the pipe. The total length Pipe uses in calculations corresponds to the specified pipe length, plus any equivalent pipe length due to valves, fittings, and miscellaneous L/D.
A MIXER block is still needed to combine the streams before the PIPE block. (The streams need to mix at the same pressure or there would be reverse flow which is not modeled in Aspen Plus though it is in Aspen Dynamics.)
Keywords: Tee
References: None |
Problem Statement: In Aspen Plus, is the Prop-Set for PH25 the same as the Prop-Set for PH with TEMP=25? | Solution: The Property Sets PH25 and PH with the Temperature specified as 25 are not the same.
PH25 is calculated by reflashing the stream at 25 C. By reflashing the stream, both the liquid composition and the activity coefficients will be changed.
PH TEMP=25 C does not reflash the stream. The compositions calculated at the actual temperature of the stream are used rather than those at 25 C. Only the activity coefficients are recalculated at 25 C. PH will equal PH25 when the stream has a temperature of 25 C.
Keywords: ASPEN PLUS, PROP-SET, PH, PH25, Electrolytes, ELECNRTL, PITZER, Property Set
References: None |
Problem Statement: When a RadFrac column model includes specifications on Murphree stage efficiencies, the K-values (= yi/xi) reported on the RadFrac Profiles K-Values Sheet do not agree with the vapor and liqiud composition profiles reported on the RadFrac Profiles Compositions Sheet. Why do the KVL-values and molar composition profiles not match? | Solution: The issue is that you are calling yi/xi the K-value, but this is true only at equilibrium. If we define
eta = efficiency
y = vapor composition exiting tray
x = liquid composition exiting tray
y* = vapor composition enterring tray
K = thermodynamic K-value
then
y - y*
eta =
--------
Kx - y*
or
(y- y*) y*
K = ------- + ---
eta*x x
Use the above equation to verify the K-values reported by RadFrac.
Keywords: RadFrac
Murphree efficiency
vapor-liquid K-value
KVL
References: None |
Problem Statement: When I select HeatX, there are many icons. Right click mouse, for example, select E-HS-1CN. What do the letters stand for? | Solution: The icons that can be used to represent a HeatX block look different but the model is the same for all of them. They, all, feature the same number/type of connections/ports. It is important to connect the right streams to the right ports (i.e. the hot stream to the hot port and the cold stream to the cold port). Only the specifications within the block will make a difference in the chosen model (e.g. shortcut, rigorous, etc.) The icons have been assigned names:
e.g.
E-HT-1CN : E is for the shell type, HT is for the hot side (H) that is the tube side (T) and 1 is for the number of tube passes, CN is for Counter-current E-HS-1CO: E is for the shell type, HS is for the hot side (H) that is the shell side (T) and 1 is for the number of tube passes, CO is for Co-current.
J12-HT1: J is for the shell type, 12 is for the divided flow applied to the shell side outlet stream, HT is for the hot side (H) that is the tube side (T) and 1 is for the number of tube passes J212-HT1: J is for the shell type, 21 is for the divided flow applied to the shell side inlet stream, HT is for the hot side (H) that is the tube side (T) and 1 is for the number of tube passes
HT and HS: It is in the location of the hot and cold ports which you can of course move around the block.
Keywords: Heatx, TEMA, type, icon, shell, tube, pass, counter-current, co-current
References: None |
Problem Statement: How to use the vent algorithm for RBatch to improve convergence. | Solution: To use the improved Vent algorithm in RBatch, specify the reactor volume and the vent opening pressure to calculate the reactor pressure rather than specifying reactor pressure. This process may help an RBatch process converge.
In Aspen Plus 10:
Specify Calculate reactor pressure on the RBatch / Setup / Specifications sheet.
Specify the Reactor volume on the same sheet.
Specify the Vent opening pressure on the same sheet.
In Aspen Plus 9:
Specify Volume on the RBATCH.Main form. (Specify volume rather than pressure).
Specify the Vent opening pressure on the RBATCH.Operations form.
If a liquid reaction occurs, then ensure that the temperature specification is below the dew point and reduce the stop criteria (time).
TIP:
If your RBatch block with vapor vent is not converging you can try changing the pressure convergence options.
In Aspen Plus 10:
On the RBatch / Convergence / Pressure Loop sheet, change the
Numerical searchSolution scheme to Modified Secant.
In Aspen Plus 9:
On the RBATCH.Convergence form and set the field Solver to ROOT1N.
Keywords:
References: None |
Problem Statement: An In-house databank or User databank has been generated for Aspen Properties and the Graphical User Interface (GUI) has also been customized to access this databank. When upgrading, what is the procedure to use these customizations? | Solution: You must rerun DFMS with the latest version to create the databank. You must also rerun the Graphical User Interface Customization (MMTBS) to include the databank in the GUI. SeeSolution 4337 for step-by-step instructions of how to create user or inhouse databanks.
WARNING When customising, you MUST save all of the customisation source files and carefully manage and test these files for future in house developments and new releases.
Keywords: user databank
inhouse databank
inhspcd
References: None |
Problem Statement: I know the characteristics of a petroleum blend and a product that will be removed from the blend. Is there an easy way to calculated the properties of remaining blend with the product removed? | Solution: Once the pseudo component compositions for the blend and products are known, one can essentially do this calculation in Excel (or by hand if you wanted to). Attached is an example using an Excel USER2 block to do the calculation.
The example contains two files, an Aspen Plus .bkp file and an Excel file. In the example, two petroleum assay are defined namely CRUDE (the feed) and OIL (the specified product).
The bkp contains a USER2 model with a feed stream (MIX) and a reference stream (REF-IN) containing the product that will be removed. The USER2 block will calculate the composition of the REMAIN stream using a pseudocomponent composition. The distillation curve(s) for the product streams can be accessed in the stream results for these streams. Please note that relative flow rates specified for streams MIX and REF-IN are important and if more product (i.e. REF-IN) is specified than that what is present in the mix, the USER2 block will return zero flow for the REMAIN stream and give an out of mass mass balance error.
In order for this example to work correctly, the generation of pseudocomponents in Aspen Plus must be explicitely specified in Aspen Plus by the user. In this case pseudocomponents PC1 to PC26 were defined in the data browser under Components | Petro Characterization | Generation. The explicit definition of the pseudocomponents allows one to refer to them directly in the USER2 spreadsheet resulting in a simpler USER2 model. In Aspen Plus12.1 and higher, 29 pseudocomponents (PC1 to PC29) are generated and specified.
The spreadsheet calculates the REMAIN composition by simply subtracting the pseudo compoment composition of the product from the mix. Provision is made in the spreadsheet to prevent more product (OIL) to be removed from the feed than is possible. Please refer to the Calcs sheet in the spreadsheet to see how this is done.
In order to run this example, save both files to the same directory. If for some reason, the USER2 Excel spreadsheet is not found, browse and specify the location of the saved .xls file. It is generally best to ensure that the path to the spreadsheet contains no spaces.
Please refer to the User Models manual, Chapter 5 for a detailed description of how to create Excel USER2 models. The manual can be found on the Aspen Engineering Suite installation CD's or can also be downloaded from our website.
Keywords: petroleum, distillation curve, pseudo component, Excel, USER2
References: None |
Problem Statement: How are the different streams in an RBatch calculated? | Solution: RBatch can operate in a batch or in semi-batch mode. The reactor mode is determined by the streams you enter on the flowsheet. A semi-batch reactor can have a vent product stream, one or more continuous feed streams, or both. The vent product stream exits a vent accumulator. It does not exit the reactor itself. The vent accumulator is for the continuous (but time-varying) vapor vent leaving the reactor. The composition and temperature of each continuous feed stream remain constant throughout the reaction. The flow rate also remains constant, unless you specify a time profile for the flow rate of a continuous stream.
Batch operations are unsteady-state processes. Variables like temperature, composition, and flow rate change with time, in contrast to steady-state processes. To interface RBatch with a steady-state flowsheet, it is necessary to use time-averaged streams. If the same time is not used to calculate the flowrate of all of the inlet and outlet streams, the streams around the block may not be in mass balance.
Four types of streams are associated with RBatch, as follows:
Batch Charge:
The material transferred to the reactor at the start of the reactor cycle. The mass of the batch charge equals the flow rate of the batch charge stream, multiplied by the feed cycle time. The mass of the batch charge is equivalent to accumulating the batch charge stream in a holding tank during a reactor cycle. The contents of the holding tank are transferred to the reactor at the beginning of the next cycle .
To compute the amount of the batch charge, RBatch multiplies the flowsheet stream representing the batch charge by a cycle time you enter (either Total Cycle Time or Batch Feed Time). Batch Feed Time is not the time required to charge the reactor; it is a total cycle time used only to compute the amount of the charge. Batch Feed Time is required when Cycle Time is unknown. If Batch Feed Time differs from the actual computed cycle time, the RBatch flowsheet inlet and outlet streams are not in mass balance. However, all internal RBatch calculations and reports will be correct for the computed batch charge.
Continuous Feed:
A steady-state flowsheet stream fed continuously to the reactor during reaction. Its composition and temperature remain constant throughout the reaction. Its flow rate either remains constant or follows a specified time profile. Reactor Product: The material left in the reactor at the end of the reactor cycle. The flow rate of the reactor product stream equals the total mass in the reactor, divided by the reactor cycle time. You can think of this process as analogous to transferring the reactor product to a product holding tank. This tank is drawn down during the next reactor cycle to feed the continuous blocks downstream.
Vent Product:
The contents of the vent accumulator at the end of the reactor cycle. During the reactor cycle, the time-varying vent stream accumulates in the vent accumulator. The flow rate of the vent product stream is the total mass in the vent accumulator, divided by the reactor cycle time.
If an RBatch is going to be integrated into a steady state flowsheet, it is important that Total Cycle Time is specified so that both the inlets and the outlets are calculated on the same basis and the block can mass balance.
Keywords:
References: None |
Problem Statement: Occasionally, the stream data tags (which display temperature, pressure, mass flowrate or duty/power on flowsheet) do not show up on the flowsheet, even though user has selected the proper items under Tools -> Options -> Result View tab and also selected Global Data under View. | Solution: This seems to be a small glitch in the program, where occasionally the Global selections do not become activated and must be refreshed manually. TheSolution is to:
Go to Tools / Options and click on the Results View tab.
In the Stream results box, deselect all options.
Click on Apply.
Now reselect all the desired options.
Click on Apply. The settings should take effect
Click OK.
Keywords: global data
stream data tags
References: None |
Problem Statement: What are the Electrolyte Inserts? How are they used? | Solution: An insert is a partial backup file that you can import into a run at any time. You can use an insert to create a:
Property package, consisting of component and property definitions
Standard process unit, such as a crude column and its preheat train
You can create your own inserts, or you can import inserts from the AspenÂPlus library of inserts. The Electrolyte Inserts are from this library. The Electrolyte Insert packages that come with Aspen Plus typically contain a list of Components, the Chemistry for the system, a Property Method designation, and the Property Parameter data that defines the interaction parameters for the electrolyte components.
The information in each Insert is provided in a backup file in the ..\AspenTech\Aspen Plus xxx\GUI\elecins subdirectory.
Notes on Insert usage
Some Insert packages were written to use the true approach and some were written for the apparent approach. In general, the data within any insert can be used with either the true or apparent approach.
Each Insert is designed to be used with one specific property method. Because Property Parameter Data within an Insert may have been regressed from liquid enthalpy or heat capacity data, it is not rigorously correct to use the data from an Insert with a different property method.
To use an Electrolyte Insert from the AspenÂPlus library:
From the File menu, click Import.
On the Import dialog box, click the Favorites button on the toolbar.
In the Favorites folder, double-click the Elecins folder.
Select an insert from the list and click Open.
Tip: To see a description on the insert, use the Preview button on the Import dialog box toolbar.
If the Resolve ID Conflicts dialog box appears, see Resolving ID Conflicts.
Tip: To view in detail the contents of an insert before using it, follow the procedure above, except open the insert using File Open, instead of File Import. Then use the Data Browser to see what input is defined in the insert and to look at the insert contents.
Keywords: elecins
References: None |
Problem Statement: Where do I find the gas treatment solvents, Selexol and Purisol, in the Aspen Plus pure component databanks? | Solution: These properties are found as described below:
Selexol
The physical properties of DOW's Selexol or Coastal Chemicals' AGR are not public information. This component is also known as Dimethyl-Ether-Polyethylene- Glycol (DEPG).
Previously, the company that licensed Selexol would work with their customers to provide the physical property information or package model systems with Selexol included in them. The component SELEXOL in the ASPENPCD databank contains only the values for molecular weight (MW=280.0) and standard liquid volume parameter (VLSTD=0.2705 cum/kmol). DEPG is in the PureXX databanks, but it also does not have much property data.
Purisol
Purisol is also another solvent used in gas treatment. You can find Purisol in the PURExx databank as N-methyl-2-pyrrolidone (NMP); its component properties are quite complete.
The property methods recommended for acid gas absorption with methanol (RECTISOL) or PURISOL are PSRK or SRK. Provide binary parameters for best results. PSRK uses a modified Unifac method for the mixing rule that incorporates special groups for many light gases. By default, PRMHV2 and RKSMHV2 use Unifac-Lyngby, and PRWS and RKSWS use Unifac. These methods do not have as many specialized groups for the light gases so their predictions should not be as good as PSRK unless Unifac binary parameters are regressed.
Keywords: NMP
References: None |
Problem Statement: What is an adiabatic Pipe? Although a PIPE model is specified to work adiabatically (zero duty), the calculated heat duty which reported among the thermal results is non-zero. What is the reason? | Solution: The difference in enthalpy is due to the change in elevation. One of the terms in the Bernoulli equation is the potential energy term, which takes into account the change in elevation. Due to the additional pressure drop caused by the elevation, the outlet stream has a different pressure and temperature. These differences in the state variables (pressure and temperature) affect the stream enthalpy, too.
Adiabatic means that no heat is exchanged with the surroundings, NOT that the enthalpy is constant. Note also that on the Results | Summary form we call the enthalpy difference Enthalpy change, not duty. Because the enthalpy of the outlet stream is different from the enthalpy of the inlet, the PIPE model calculates a non-zero enthalpy change in order to maintain the enthalpy balance around the block. The duty is zero, but the enthalpy change is not.
In V7.4, a duty variable will be added for PIPE/PIPELINE which will be shown as the global data for the block.
Keywords: None
References: : CQ00430611 |
Problem Statement: Why is the AMINES propery method warning displayed for a system where the limits are not exceeded ?
The file runs and gives several warnings of the type:
WARNING IN PHYSICAL PROPERTY SYSTEM WHILE GENERATING REPORT FOR STREAM: OUTLET THE AMINE CONCENTRATION OF 59.8 WEIGHT PERCENT IS OUTSIDE THE VALID RANGE OF 5.0 TO 40.0 WEIGHT PERCENT. THE AMINES OPTION SET WILL NOT BE USED. CHAO-SEADER MODELS ARE USED INSTEAD
However, the amine concentration is much less than 59.8 weight percent in the flowsheet. | Solution: At first sight, this may seem unreasonable, since the concentration of the amine is 15 % b.w., which is well in the admittable range.
The message leaves the user with the impression that Chao-Seader is used for all the calculations. This is not the case. Chao-Seader is only used for the calculation where the concentration is out of range. If the oveall property method is changed to Chao-Seader, the results will be different.
Often the errors are not issued during the normal computations, but during the generation of the report. It is a property set calculation such as one that requests TDEW that causes the messages to appear. The limit of applicability of the AMINES property method is exceeded only in the computation of the property set, whose result may be incorrect, but the rest of the computations should be fine.
The error can also occur during the process of converging the flash calculation. This is understandable because concentration may change during the flash iterations. The flash algorithm calls various thermodynamic routines, and these warning messages can come during this process.
Keywords: AMINES property method
Kent-Eisenberg
References: None |
Problem Statement: There are problems installing Aspen Plus 2004.1 Cumulative Patch 4. It will return errors when someone tries to apply it. If Aspen Plus 2004.1 is installed and there is no cumulative patch applied, then CP4 will install with no problems.
If CP1 or CP2 are installed, then CP4 will not install and it will complain about not finding a .tmp file.
If CP3 has been applied, then CP4 will install with no problem.
Cause
CP4 was initially created incorrectly to only install on the previous cumulative patch. It was posted for a brief time on the web site before it was replaced. The incorrect version of CP4 was around 54 Mb. The correct version is around 74 Mb. | Solution: First, after a failed installation of Cumulative Patch 4, start Aspen Plus. The messages about installing are normal as Aspen Plus needs to repair itself. Let this process run its course. Open a test file and verify that Aspen Plus is still working. Then exit.
Next, download and re-apply Aspen Plus 2004.1 Cumulative Patch 4. It should install without problems.
Keywords: None
References: None |
Problem Statement: What is the meaning of the number (-1) for element 5 of UFGRP in the parameter report for trichloroethylene (see Properties Parameters Results Pure Components T-Dependent Sheet)? | Solution: If you take a look at the Physical Property Data
Keywords: UNIFAC
UNIF-LL
UFGRP
Parameter Report
Special UNIFAC Liquid-Liquid Functional Groups
Group Contribution Methods
References: Manual, Chapter 3, Table 3.13, you will notice that trichlorethylene belongs to a group of components for which special UNIFAC liquid-liquid functional groups exist. As both property methods (UNIFAC and UNIF-LL) use the same parameter (UFGRP) to get their structural information, the -1 in element 5 serves as a switch. In other words, it causes Aspen Plus to use the groups 1055 and 2800 with ordinary UNIFAC and group no. 3150 with UNIF-LL. You can see the same behavior for all components listed in table 3.13, except for sulfolane. The reason is that for sulfolane there is no choice but to use group no. 3250. |
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