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Problem Statement: Are Knock Out Drum (KO Drum) sizing calculations possible in Aspen Flare System Analyzer (Aspen FLARENET)? | Solution: Prior to Aspen Flare System Analyzer V7.0, knock out drum sizing calculations were NOT possible. Aspen FLARENET could only do pressure drop calculations across a knock out drum. In Aspen Flare System Analyzer V7.0 and later, it is possible to size horizontal and vertical knock out drums according to the sizin... |
Problem Statement: In Aspen Flare System Analyzer exported files, there are some numerical values (0, 1, 2) to represent the configurations of the network and set up. Where can I find those meanings of numerical values? | Solution: You can find those information in Appendix B (File Format) of
Keywords: Export, Import, MS Excel, MS Access, XML
References: Manual. Only missing number is -32767, which represents EMPTY in Aspen Flare System Analyzer. |
Problem Statement: How is the acceleration pressure drop calculated using a homogeneous method? | Solution: The acceleration pressure drop is calculated using the equation below.
Acceleration pressure drop = Outlet (mass flux^2 / density) - Inlet (mass flux^2 / density)
Keywords: Acceleration pressure drop, mass flow, density
References: None |
Problem Statement: How to transfer Model Summary to Aspen Simulation Workbook (ASW)? | Solution: If you wish to export the model summary information to ASW then you need to select the Send to Excel/ASW option.
After you select this make sure you select the highlighted Export Option and then click Export tables to Excel as shown in the screenshot below.
Provide a file name and then once it is exported a ... |
Problem Statement: Does Flarenet use the Fixed Roughness value on the Options settings for the pressure drop calculations of the pipe? | Solution: The fixed roughness value specified in the calculation options is used for the equivalent length calculation for the pipe fittings. The program always uses the roughness value specified on the dimensions tab for actual pipes.
Keywords: Fixed roughness, equivalent length, pipe fittings
References: None |
Problem Statement: Why doesn't the pipe sizeable feature show as a dotted line on the Process Flow Diagram? | Solution: It works in design mode only. Run the case file in design mode.
Keywords: Sizeable, PFD, Dotted
References: None |
Problem Statement: How does Aspen Flare System Analyzer size Relief Valves using the HEM method. | Solution: The HEM method is based on the Homogeneous Equilibrium Model and assumes no slip conditions and thermal equilibrium between each of the phases.
A detailed description of the method may be found in the following reference; Leung, J.C. , Easily Sized Relief Devices and Piping for Two-Phase Flow, Chemical Engine... |
Problem Statement: Sometimes in Ver 7.3, when you want to enter pipe diameters manually, it gives messages to enter diameters not smaller than 1000mm. | Solution: This is a known issue, the reason is Aspen Flare System Analyzer does not appreciate , instead of . in some language setting as a decimal point. Right now there are 2 workarounds for this problem
First approach:
Go to Control Panel | Regional languages and options | set the language to English(United States)
... |
Problem Statement: How are 'upstream static pressure', 'static source back pressure' and 'system back pressure' defined in Aspen FLARENET? | Solution: Upstream static pressure refers to the static pressure at the inlet of the pipe.
Static source back pressure refers to the static pressure at the outlet flange of the source.
System back pressure refers to the static pressure at the outlet of the flare tip. By default, this is set to atmospheric pressure.
K... |
Problem Statement: How is Static pressure calculated? | Solution: The Static pressure is calculated based on Bernoulli's principle:
Static Pressure (P/rho) + Velocity head (V^2/2) + Elevation(z*g) = Constant (for no frictional loss).
where... |
Problem Statement: How does Aspen Flare System Analyzer model hot tap in relief system? | Solution: There is not a direct way to model the hot tap. You have to use the tee to connect to Header. Then you can add a zero length pipe (with proper diameter) between tee and tail pipe. Then you can add the fitting to this pipe. In order to do it, you can create your own fitting (Database->Pipe fittings).
Keywords:... |
Problem Statement: How does one add components, pipe schedule and fittings to the FLARENET database? | Solution: There are two ways to edit the FLARENET database:
1. In Aspen FLARENET, select Database | Component / Pipe Schedule / Pipe Fittings from the main menu, then click on the Add button in the ensuing form. Refer to the image below:
2. Edit the FLARENET database using MS Access. The location for the FLARENET dat... |
Problem Statement: How is the Downstream Density calculated in Aspen Flare System Analyzer? | Solution: The vapor density calculations are based on Static Pressure (Ps) not Total Pressure (Pt). This pressure is always used for the physical properties. Hence vapor density is calculated as follows:
Attached is a sample file with an example of the density calculation. Note that KB #116954 explains how is the s... |
Problem Statement: How are the phase fractions defined in Flarenet? | Solution: The Upstream Fraction and Downstream Fraction reported on the View\Results->Physical Properties page (note you must have the Save Phase Properties option selected on File\Preferences to see these results) and the Vapour Fraction results reported on the PFD are phase molar fractions.
Thus for the vapour phase ... |
Problem Statement: How can I make the pressure drop calculation across the flare tip dependent on flowrate? | Solution: Typically, the pressure drop across the flare tip is calculated with the standard fittings correlation, e.g. K = A + B*Ft, where Ft is the turbulent friction factor. Using this approach, the pressure drop variation will not be all that large given any change in the flow through the flare tip. Many flare tip m... |
Problem Statement: How can I change VLE, enthalpy and pressure drop calculation methods for all objects? | Solution: You can change VLE, Enthalpy and pressure drop calculation methods for all objects. Go to Calculations || Options || Methods. The following picture shows the interface.
Keywords: Overall, VLE, Enthalpy, pressure drop, method, multiple objects, all objects
References: None |
Problem Statement: How to prevent the error, operation must use an updateable query when creating the user pipe schedule | Solution: This problem could arise from the pipe database in the file being read-only and can't be edited. Access files have different password security options that may have been activated.
OneSolution is to try and open the database file directly with Access to investigate if it can be modified from the following add... |
Problem Statement: How to add View Point in Aspen Flare System Analyzer V8.2 | Solution: Adding different View Point in Aspen Flare System Analyzer will help you navigate large pipe network and quickly find the objects you are looking for. ThisSolution will introduce how to add How to add View Point in Aspen Flare System Analyzer 8.2.
1. Look at your whole network and divide different zones. ... |
Problem Statement: Why is there no graphical profile displayed for my model? | Solution: No graphical profile will be shown in Aspen FLARENET if flow is splitting or merging together in a flow network (i.e. there is no single path for which a profile can be displayed).
Refer to the attached file 'Sample-C1.fnw', where a graphical profile is displayed.
In the file 'Sample-S1.fnw', no graphical pro... |
Problem Statement: How do I quickly find objects (pipes, relief valves etc) on the PFD? | Solution: To find objects on the PFD, click on the PFD. Hold down the <ctrl> key and press the F key. A list of all the operations in the PFD will appear. Scroll down the list and select the specific operation you are looking for. Once you have selected the desired operation, Aspen FLARENET centres the PFD at the objec... |
Problem Statement: What is happening to my temperatures and pressures in dead parts of the flare network? | Solution: Where no flow exists in part of the flare network, i.e. branches are connected to relief sources with no flow, Aspen FLARENET follows the following rules for pressure and temperature displayed on the PFD:
1. Aspen FLARENET propagates the source temperature forwards until it meets a pipe with a non-zero ... |
Problem Statement: What is the Relieving Pressure and how is it calculated in Aspen Flarenet? | Solution: The Relieving Pressure is the pressure increase over the Maximum Allowable Working Pressure (MAWP) allowed during discharge of the relief device. In API 520 this is termed the Accumulation or Accumulated Pressure.
According to API 520, the value of the Relieving Pressure is 110% of the MAWP for Operating cont... |
Problem Statement: What operating system (OS) requirements does FLARENET need? | Solution: Operating system requirements for FLARENET installation:
The Windows Installer being used by FLARENET requires Internet Explorer 4.02 or higher. We believe there may be some issues with the SLM installation on IE4 so we would suggest IE5 for safety if this is possible.
Under WinNT, FLARENET requires Service P... |
Problem Statement: What is the difference between solved on pressure and solved on flow in the Trace window? Is it possible to force the convergence to be solved on pressure? | Solution: The Solved On Flow indicates that FLARENET has been able to solve the mass balance of your looped flare system to within the mass balance tolerance but has been unable to achieve the pressure convergence tolerance. The tolerances for your FLARENET model are set on the General tab under the Calculation - Optio... |
Problem Statement: What does the Elements / Two Phase Elements input variable represent? | Solution: The Elements / Two Phase Elements in the Aspen FLARENET pipe model defines the number of cells into which the pipe is divided for pressure drop calculations when a two phase pipe pressure drop method is used (even if the flow is actually single phase).
For Aspen FLARENET 2004 and onwards, this option was rena... |
Problem Statement: What are improvements in the Process Flow Diagram (PFD) for Aspen Flare System Analyzer V7.3? | Solution: ? Copy and paste in the Process Flowsheet is now allowed.
? New zoom capabilities in the Process Flowsheet.
? Connecting objects in the Process Flowsheet has been significantly improved.
? New Grid controls used in Results and Input Views let you sort and apply a custom f... |
Problem Statement: What are the differences between the 2.56 and 3.x program calculations? | Solution: When importing a model from FLARENET version 2.56 into 3.0x, the user should be aware that there is a fundamental change in philosophy. The wide range of philosophy changes leads to different answers when importing directly a 2.56 case into 3.0x. This article deals with the changes necessary to compare the re... |
Problem Statement: Is the fitting database network-based or computer-based? Do we need to add new fittings every time we open the model in different computers? | Solution: When you customize the fittings database the files are available on the computer you have modified. If you want to send the Flarenet file to someone else you have to send the fittings.mdb file as well. It is located under C:\Documents and Settings\All Users\Application Data\Aspen Tech\Aspen FLARE NET (version... |
Problem Statement: How to create a Black Oil fluid package in Aspen HYSYS? | Solution: To create a Black Oil fluid package in HYSYS you will need the HYSYS Upstream installed. The Black Oil package is available under the COMThermo group.
It is recommended to add a list of light components first with the Peng Robinson property package to represent the light end gas composition
In the Simulation ... |
Problem Statement: Can I fix the outlet pressure / back pressure of a relief / control valve?
Can I control the outlet pressure / back pressure of a relief / control valve? | Solution: Aspen Flare System Analyser (formerly Flarenet) performs the hydraulic calculations backward (from flare tip to source). As a result the flare system will dictate the outlet pressure of the control/relief valve. You can not specify an outlet pressure of a valve. You can control it by controlling pressure drop... |
Problem Statement: How do I change the value used for atmospheric pressure? | Solution: To change the atmospheric pressure value used in all calculations, go to the Calculations menu and select Options. The Atmospheric Pressure field is located at the top of the General page. Once you have made your change, click on the OK button.
Keywords: flare tip
References: None |
Problem Statement: Are the Expansion/Contraction losses in Separators accounted for? | Solution: The separators (Knock Out Drum) in Aspen Flare System Analyser includes expansion/contraction losses associated with the piping connections for the inlet and outlet respectively. Therefore if pipe exit losses are accounted for from Pipe fitting, losses will be accounted twice. This might lead to an over predi... |
Problem Statement: How can I zoom in on separate sections of the PFD without having to zoom in and out constantly? | Solution: In some Aspen FLARENET cases, the PFD can become quite large and it becomes difficult to locate and view sections or areas of a flare system comfortably and legibly. The PFD has the facility to create multiple viewports. A viewport is essentially a specific view focused on one particular section of the full P... |
Problem Statement: What are the methods used for relief valve sizing in Aspen FLARENET? | Solution: In Aspen FLARENET version 2004 and higher there are three different methods available for sizing a relief valve (calculating the rated flow) in Aspen FLARENET: HEM, API 1976 and API 2000. Versions of Aspen FLARENET prior to version 2004 have the HEM and API 1976 methods available. The sizing method can be cho... |
Problem Statement: Why is the friction factor different if calculated by Beggs & Brill and Adiabatic methods when we have some water in the vapour? | Solution: When you have a VF=1, there is no difference between the Adiabatic method and Beggs & Brill method as the friction factor ratio is 1, as per the Beggs and Brill model in this case.
However, when there is liquid present and we have two phases, the friction factor is correctly calculated for vapour fractions ... |
Problem Statement: Is it possible to specify a pipe elevation greater than its length? | Solution: No, the pipe length in Aspen FLARENET is its total length, so it cannot be less than the elevation. A total pipe length that is less than the elevation can result in flash errors when the model is run.
Keywords: pipe length, elevation
References: None |
Problem Statement: What options are there for modelling the nozzle losses at the inlet and outlet of the separator in Aspen Flare System Analyzer? | Solution: The available options are:
A? Equal Static Pressure - Pressure drop calculation is ignored and static pressure in the inlet and outlet is equal.
A? Calculated Ignore Vena Contracta - Pressure drop is calculated in accordance with the Swage method but ignores the loss due vena contracta
A? ... |
Problem Statement: What does the trace buffer size in Preferences / General do? | Solution: This options lets you to specify the size in bytes of the text buffer displayed by the Trace window. Larger values will allow more text to be stored. The default value of 32000 is adequate for most cases.
Keywords: Trace buffer size, preferences
References: None |
Problem Statement: When should the kinetic energy contribution option be used? | Solution: For a rigorous design, the kinetic energy option should always be checked (i.e. select Calculation | Options from the main menu and activate the Include Kinetic Energy checkbox on the General pagetab). Not taking into account the kinetic energy changes in a simulation could culminate in less accurate results.... |
Problem Statement: Can Aspen Flare System Analyzer calculate the Sound Power Level (SPL) due to Acoustically Induced Vibrations (AIV) within the flare header piping? | Solution: Aspen Flare System Analyzer V9 can calculate the SPL due to AIVs. Noise generated by gas flowing through high pressure drops across mechanical equipment like control valves, orifices, or relief devices may cause high-frequency vibrations in the pipe wall. This high-frequency vibration (i.e. AIV)Â can cause f... |
Problem Statement: What is recommended value of Mach number in Aspen Flare System Analyzer? | Solution: While rating the network you may define a Mach number constraint of 1.00, in order to highlight only choked flow conditions.
Mach number of 1.00 is NOT recommended for design calculations where a more reasonable value such as 0.5 or 0.7 will lead to a more rapidSolution towards the maximum allowable back pres... |
Problem Statement: How can I tell if one of my constraints has been violated for a particular scenario? | Solution: When a scenario's calculations have been completed, there is a variety of ways to find out if one of the constraints has been violated:
Look at the PFD. Anything that appears in red, i.e. the name of a pipe segment indicates that one of the constraints has been violated. Unfortunately, no indication of which ... |
Problem Statement: I get a message 'choked flow at flange for source', whenever I input a flange diameter for my sources. Once removed the flange diameter(s) the message(s) disappear. | Solution: 1) If you get a choked flow error message at the outlet of the source it indicates that the source outlet flange diameter is not sufficient to relieve the flow. Hence the choked flow message appears. You need to find out from the relief valve vendor what is the allowable diameter of the outlet fla... |
Problem Statement: How does Tee's pressure drop calculate in Flarenet? | Solution: The static pressure change across the TEE is given by:
DeltaP = Tee's Pressure drop
K = static pressure loss coefficient
V = Average Velocity of fluid across Tee
Tees pressure drop are modeled either by using a flow independent loss coefficient for each flow path or by using variable loss coefficients that ar... |
Problem Statement: How do I create a new scenario from my existing FLARENET case? | Solution: It is a relatively easy task to create a new scenario in an existing FLARENET case. It is good practice to build the Default Scenario or your base case to include all equipment which currently exists in or may be included in the flare network. Once you are satisfied that your default scenario is complete and ... |
Problem Statement: What is the Maximum Allowable Back Pressure (MABP) and how is it calculated in FlareNet? | Solution: The Maximum Allowable Back Pressure (MABP) on a relief device is the maximum pressure that can exist at the outlet of the device without affecting the capacity of the device.
In general the MABP for a conventional pressure relief valve should not exceed 10% of the set pressure at 10% overpressure. For a balan... |
Problem Statement: Can I choose which scenarios should be calculated when I run my FLARENET model? | Solution: Yes, it is possible to pick which scenarios are to be included in the calculations when you run your model. There are three options available on the Scenarios page of the Calculation Options Editor:
Current Scenario: only the current scenario is calculated.
All Scenarios: all scenarios are calculated sequenti... |
Problem Statement: Why is the Source Back Pressure not equal to the Upstream Pressure in a tailpipe? | Solution: If there is a change in flow area between the source flange and the downstream tailpipe, Aspen FLARENET will perform a swage calculation across this diameter change (unless you have specified otherwise). This leads to a pressure difference between the Source Back Pressure (the pressure at the source flange) a... |
Problem Statement: Is the swage option taken into account in the inlet piping? | Solution: No. Currently, there is no option to take into account contraction or swage in the inlet piping.
Hence, the Swage option that is shown under the Methods tab in the valve refers only to the outlet.
As a workaround, you can include an equivalent length in the inlet piping to take into account the pressure losse... |
Problem Statement: When I run a Flare System scenario I get multiple note messages stating Recycle Molar at 'segment name'. The scenario then fails to converge. | Solution: These error messages appear if during theSolution of the network topography discovers a separator unit operation within the body of a looped circuit. (This configuration is indicated by a separator whose fluid flow direction is unknown until after calculations are complete). This toporgraphy is not supported ... |
Problem Statement: How is the flare tip pressure drop calculated from the diameter and fittings loss coefficient specified in the Flare Tip Editor? | Solution: The static pressure drop of a flare tip in Aspen FLARENET is calculated from the following equation :
dP = 0.5 K Rho * v ^2
where :
dP = Pressure drop
K = Fittings loss coefficient
v = Velocity
Note : The diameter of the attached pipe has no impact upon the pressure drop calculation and Aspen FLARENET does n... |
Problem Statement: I have very big network for relief system. How do I find or locate the particular valve or pipe segment on PFD? | Solution: In Aspen Flare System Analyzer V7.2 or previous versions, you can use the shortcut key Ctrl + F. Aspen Flare System Analyzer will pop up the interface: Locate Object.
If you click the desired Object, Aspen Flare System Analyzer will bring you to the location and highlight the object.
If you use the Aspen Fl... |
Problem Statement: Where does the K=8 fixed value come from when using the Miller Chart NO extrapolation method in a Tee? | Solution: As you can find in the
Keywords: Miller Chart, Gardel
References: Manual ( |
Problem Statement: Open Profile graphical view - does not show any profile | Solution: It is due to loop in the system. User would need to ignore some of the pipes so that flow path does not form a loop.
Keywords: profile, loop
References: None |
Problem Statement: How is the rated flow calculated for a relief valve ? | Solution: On the Conditions page of the relief valve view, there is a Set button located next to the Rated Flow cell, which when clicked will calculate the rated flow for that specific valve. Before calculating the rated flow, the user should first ensure that the valve dimensions have been input properly. On the Dimen... |
Problem Statement: Is it possible to change the source data for all scenarios? | Solution: In Aspen Flare System Analyzer, each scenario will hold its own data. It means that source data (composition, pressure, temperature, flowrate) are being shared among scenarios.
You will have to change one scenario a time.
One workaround is to export your data into the Excel file by Export Wizard. You can mani... |
Problem Statement: What is the difference between the fittings Tee-Standard and Tee-Swept? | Solution: The difference is the angle between the branch and the body. A Standard tee has an angle of 90 degrees. A Swept tee has an angle typically between 30 and 60 degrees.
Keywords: Tee, Standard, Swept, Fittings
References: None |
Problem Statement: In Aspen Flare System Analyzer, why the Flow Map is reporting Annular flow while the Pipe Summary is reporting Slug flow and also a slug flow warning message appears. | Solution: In Aspen Flare System Analyzer (AFSA), flow regime results are reported in Flow Map and also in the Summary page of each pipe unit (seeSolutions 131382 & 134868). Sometime user may received different results from the two reports, such as annular flow in Flow Map and slug flow in pipe Summary page.
The reaso... |
Problem Statement: Is it possible to fix a constant pressure drop in a flare knock out (KO) drum? | Solution: In Aspen Flare System Analyzer, it is not possible for the user to fix a constant pressure drop in the KO drum, since KO drum only considers inlet and outlet pressure changes. However, the user can model a bleed for a fixed (constant) pressure drop between two KO drums to represent the horizontal separator.
S... |
Problem Statement: How do I change the units used to display the calculated values? | Solution: There are two ways to change the display units:
Go to the File menu and select Preferences. The units can be changed via the Display Units drop down box.
Directly below the menus at the top of the Flarenet window is a row of icons. There are two icons located directly to the right of the printer icon. Pressin... |
Problem Statement: What does the r/d ratio shown for elbow fittings on the pipe Fittings tab refer to? | Solution: The r/d ratio in an elbow fitting is the ratio of the curve radius to the diameter of the fitting. This is a standard term for bends in elbows that defines how sharp or shallow the bend is.
In Aspen FLARENET, the pressure loss coefficients are taken from the Crane Manual (Technical Paper 410) appendix A-29 ... |
Problem Statement: How do I model a seal drum more accurately? | Solution: A typical flare stack seal drum can be represented by the following diagram. Those drums can be either horizontal or vertical.
The major pressure drop through seal drum comprises 3 components. In here, we can ignore frictional losses and losses due to drum internals and direction changes within the drum body ... |
Problem Statement: How to get volumetric flow rate in the Aspen Flare System Analyzer results summary. | Solution: You cannot add volumetric flow rate in Aspen Flare System Analyzer Results| Pressure / Flow Summary. However, you can do the calculation outside Flarenet, e.g. using Excel. Starting from V7.3, you can export these summary results into excel. In the results table, you will see Mass Flowrate, velocity and Rhov2... |
Problem Statement: When I run a Flare System scenario I get multiple note messages stating Recycle Molar at 'segment name'. The scenario then fails to converge. | Solution: These error messages appear if during theSolution of the network topography discovers a separator unit operation within the body of a looped circuit. (This configuration is indicated by a separator whose fluid flow direction is unknown until after calculations are complete). This toporgraphy is not supported ... |
Problem Statement: Flarenet launch some times fail on Windows 2003 R2 with an error message popped up. | Solution: 1. Right-click My Computer, select Properties.
2. Select Advanced tab
3. In the Performance section, click Settings
4. Select Data Execution Prevention tab in Performance Options Window. select option Turned on DEP for all programs....those I select
5. Click Add... Locate the EXE file of Flarenet, and check t... |
Problem Statement: What value of the multiphase discharge coefficient (Relief Valve Editor | Methods tab | Multiphase Cd) is used for rated flow calculations using the API 2000/HEM sizing method? | Solution: If either of the API 2000 or HEM methods are selected as the sizing method (Relief Valve Editor | Methods tab | Sizing Method), Aspen Flarenet uses the following discharge coefficient values for rated flow calculations:
1. If the flow is single phase vapour at the inlet and the outlet of the relief valv... |
Problem Statement: How can one display stream properties in Aspen FLARENET? In the summary tab of a unit's edit view, I can find select process conditions but no physical properties? | Solution: Physical properties are reported at upstream and downstream conditions for every object in Aspen FLARENET. To view all physical properties, select View | Results | Physical Properties from the main menu.
Note that one cannot double click on a stream and view its physical properties, since a connection between... |
Problem Statement: What criteria does Aspen FLARENET use for its Possible Ice Formation warning? | Solution: Aspen FLARENET will display this warning if the stream contains water and the temperature of the stream is less than 0 oC (32 oF).
Keywords: Ice Formation
References: None |
Problem Statement: How do I convert a case from Aspen Flare System Analyzer V7.3 or newer to V7.2 or older versions? | Solution: In order to downgrade your case in Aspen Flare System Analyzer V7.3, you will have to use Export Case In pre-V7.3 XML format.
Set up the file name and path.
Then launch the older version such as Aspen Flare System Analyzer V7.2. Go to File->Import Wizard. Follow import procedure and use default defini... |
Problem Statement: I have an empty data base and need to create a new model. Can you give me some advice on how to begin? | Solution: Use the starter model of APS and send this model to SQL, these are the steps needed:
1. Create the model tables in an SQL database using the script to create tables found in the application folder:
2. Create a DSN file pointing to that database.
3. Copy the starter model using the DBCOPY utilit... |
Problem Statement: Aspen FLARENET seems to run very slowly - how can I speed up the calculations? | Solution: You can speed up calculations in Aspen FLARENET by doing one or all of the following:
1. Turn off the status bar at the bottom of the screen. This is done by unchecking the Show Status Bar checkbox under File | Preferences | General. Turning off the status bar can free up to 25% of the PC CPU resources ... |
Problem Statement: Where is the Sort Scenarios option in Aspen Flare System Analyzer V7.3? | Solution: Sorting scenarios has been replaced with a filter option. You can use the filter query to show / hide particular scenarios.
You can choose (Custom) to add customized filter query.
Keywords: Scenarios
References: None |
Problem Statement: Noise Calculation has been improved in Aspen Flare System Analyzer V7.3 | Solution: In previous version of Aspen Flare System Analyzer, pipes with a negative pressure drop will have a 0 noise value. Now, Aspen Flare System Analyzer V7.3 will give the correct calculated value.
Keywords: Noise, a negative pressure drop, pipe.
References: None |
Problem Statement: What does the message No FlowPath Data for Source mean when viewing the Profile results? | Solution: The Profile form (accessed via the View->Results->Profile menu) is used to display FlareNet results (pressure, temperature, flow etc.) along a flow path from the specified source to the flare tip.
In general such a profile can only be plotted if there is a single, unique flow path from the source to the flare... |
Problem Statement: How is the K term (the ideal gas ratio of specific heats) used in Aspen Flare System Analyzer? Is it Cp/Cv or Cp/Cp-R? | Solution: API 520, specifically recommends the K term should be ideal, not the rigorous one, hence Aspen Flare System Analyzer uses Cp/Cp-R.
Keywords: Ideal Gas Ratio, Specific Heats
References: None |
Problem Statement: How to generate a PDF report in Aspen Flare System Analyzer | Solution: In Aspen Flare System Analyzer (AFSA) you have an option to generate a PDF report under File menu, selecting the Print option.
The Print editor allows you to select the information you want to show in your PDF report. The available items are the same that AFSA shows in the Navigation Pane.
Before printing the... |
Problem Statement: Why do Inlet piping non recoverable pressure drop warnings appear even when the pressure drop is below the 3% of MAWP? | Solution: There is a minor bug in Aspen Flare System Analyzer V7.3, where even the calculated values are below 3% of MAWP, the warnings are still generated. The work around is to go to Options tab, and manually put in a barrier as 3%.
Keywords: warning, inlet piping, pressure drop 3%, MAWP
References: None |
Problem Statement: How to import composition to Aspen Flare System Analyzer V7.3? | Solution: Aspen Flare System Analyzer V7.3 currently does not allow user to copy/paste composition from Excel to sources directly. However, to avoid inputting composition one by one, user can use Aspen Hysys as a workaround:
1. Create one stream in Hysys. Copy the composition from excel to Hysys and make sure the strea... |
Problem Statement: Why won't my FLARENET version 2.53 or 2.52 case open in version 3.0 properly? | Solution: FLARENET version 3.0x is designed to be able to read in cases saved in versions 2.55 or 2.56. When cases saved in versions older than 2.55 are read into version 3.0x, the program will produce a blank PFD and none of the data will have been converted. These old cases will need to be opened and saved in either ... |
Problem Statement: Why are the specific heat ratio and compressibility empty in the relief valve editor? | Solution: Specific heat ratio (K(Cp/Cp-R)) and compressibility will be calculated when you will ask the solver to calculate the Rated flow i.e. when you will check the Auto box for rated flow as below:
If you input your own value of Rated flow or Auto box is not checked, then these fields will be blank.
Keywords:
Refe... |
Problem Statement: I want to see the properties and composition of the liquid flow that is removed from the knock out drum. | Solution: Because Aspen Flare System Analyzer is meant to work mainly with gas flows, knock out drums automatically remove all the liquid flow from the inlet. If you want to see the properties and composition of the liquid leaving the drum two approaches exist. The one you choose will depend on the accuracy of the valu... |
Problem Statement: How should I connect the different unit operations in my PFD? | Solution: When connecting the unit operations, we always need to remember to do so on the direction of the process flow (i.e. from left to right).
If we follow the color code on the PFD we will notice that the red dots at the border of any block represent an inlet, while the blue dot represents an outlet.
When we have ... |
Problem Statement: How to model inlet pipe work to PSV's with pipe diameter changes? | Solution: There is no option to have multiple pipe diameters in the inlet pipe to PSV. The workaround is to consider inlet pipe as inlet pipe to the PSV and add pipe length for reduced/increased diameter by fifth order of pipe diameter ratio i.e.:
Equivalent length = (Length of inlet pipe @D1) + (Length of pipe @ D2) X... |
Problem Statement: What property models are available for use in an Aspen Hydraulics Sub-Flowsheet? | Solution: Aspen Hydraulics requires either a COMThermo or Aspen Properties fluid package in order to function properly. When a native HYSYS property package is assigned to an Aspen Hydraulics Sub-Flowsheet, HYSYS creates a COMThermo property package to use. Currently, the only property packages that HYSYS can convert t... |
Problem Statement: What are the best options to have a good consistency of Calsep PVTSim files in Aspen HYSYS? | Solution: Calsep PVTSim information can be transferred to HYSYS using two different options:
· PSTSim Database Text File Import: This option is available for all AspenTech HYSYS users. Any problem detected while using this option should be reported to AspenTech for review and this is the recommended option to ... |
Problem Statement: What is the difference between property giveaway and an infeasibility breaker in Aspen Refinery Multi-Blend Optimizer? | Solution: An infeasibility breaker comes into play when the optimizer cannot find an optimalSolution in the feasible region because of some constraint defined in the model. So, the optimizer will try to find aSolution beyond the bounds and will put a penalty on objective function. This way a user will still get a feasi... |
Problem Statement: What is the difference between molecular seal and water seal and how can I model them in Aspen Flare System Analyzer? | Solution: Molecular seal
Water seal
Refer to www.johnzink.com
Refer to www.nao.com
Molecular seal and water seal drums are the accessories of a flare system that protects the stack from flame front or flash back.
Molecular seals:
1. Molecular seals work based on the difference between the density of the air and h... |
Problem Statement: How is the pressure drop across a Flare Tip calculated using Pressure Drop Curves? | Solution: Many flare tip manufacturers will supply their own characteristic curves for the flare tip, normally given in terms of the pressure drop versus flowrate.
The main features of the Pressure Drop Curves in FlareNet are:
They allow the user to input characteristic pressure drop curve data and therefore to calcula... |
Problem Statement: Are there any examples of programmatically accessing and controlling Aspen FLARENET through OLE Automation?
In Aspen Flareent, the OLE example doesn't work. | Solution: There are several examples in the \Samples\Ole sub-directory of the Aspen FLARENET installation. Additionally other examples will be posted in this folder as they are created.
Information on automation with Aspen FLARENET can be found in Section 12 of the Aspen FLARENET
Keywords: OLE Automation
References: Ma... |
Problem Statement: Can I have multiple databases to use in different projects? | Solution: Yes, by editing the databases and storing them on your PC in different directories you can use them for different projects. This applies to the piping, fittings and component databases.
Keywords: databases , projects
References: None |
Problem Statement: To run silent installation for Aspen Flare System Analyzer EP patches (or any executable patches in general) | Solution: There is a command line for the patch, which in this case is from KB 132848.
In this example:
Emergency Patch (Aspen Flare System Analyzer V7.3): EP10: Summary
of all hot fixesSolution ID:
132848
Product(s):
Aspen Flare System Analyzer
Version(s):
V7.3
Primary subject:
Patch, Cumulative Patch
Last Modified:
1... |
Problem Statement: Is the Orifice area per valve field on the Relief Valve, a user specified value? | Solution: In the Relief Valve Editor, under Conditions tab, you will see the Orifice area per valve field.
Aspen Flare System Analyzer (AFSA) does not have the capability of calculate a valve orifice size. Hence, user must enter this value.
You have the option to select one of the API 526 standard orifice sizes from th... |
Problem Statement: What is the velocity value shown on the summary tab of the pipe segment and how is it calculated? | Solution: The velocity on the Summary tab is the superficial velocity. It is calculated using simple formula:
V=Q/A, where Q is volumetric flow rate and A is pipe area
When it is a two phase stream, it represent the bulk superficial velocity which is the sum of superficial gas velocity and superficial liquid velocity. ... |
Problem Statement: How is the valve outlet temperature calculated in Aspen FLARENET? | Solution: If you have selected Ideal Gas as the enthalpy method, Aspen FLARENET is not able to calculate the source outlet temperature, and hence you are required to specify a value in the Outlet Temperature field for the valve.
If you have the enthalpy method set to something other than Ideal Gas (e.g. Peng Robinson... |
Problem Statement: How do I increase the display accuracy in Aspen Flare System Analyzer? | Solution: The user can increase or change the display accuracy (decimal points) of data in Aspen Flare System Analyzer. This can be done via File/Preferences. From the Preference Editor select Formatting tab and then click on Edit Variable Formats
This will display Variable Formats Dialog window where the user can sel... |
Problem Statement: Whats the difference between the simple and the Miller Methods for calculating a tee piece? | Solution: The simple method takes into account the relative diameters of the run, branch and tail in calculating the k factors.
The Miller method uses the relative flowrates as well as the diameters in calculating the k factor. This gives a much better accuracy.
Keywords: Miller, Tee, Simple
References: None |
Problem Statement: What does the Use Pipe Class check box in the pipe segment refer to? How do you set up the Pipe Class editor? | Solution: The Use Pipe Class check box in conjunction with the Pipe Class editor allows the user to define which pipe schedules are available for specific pipe diameters. One advantage is that this allows the user to restrict a certain pipe diameter to a particular schedule or prevent that diameter from being available... |
Problem Statement: How do I import components from Aspen HYSYS to Aspen Flare System Analyzer? | Solution: 1. Select File | Import Sources| Aspen HYSYS Sources from the main Aspen Flare System Analyzer menu.
2. Click on the Browse button and choose the Aspen HYSYS simulation file you wish to use as a data source, then press the Open button near the bottom right corner of the dialog to confirm your selectio... |
Problem Statement: According to Crane reference, the friction velocity factor for fittings is K = C*fT,
Where fT is the fully turbulent friction factor for clean carbon Steel. With that in mind, K is only dependant of diameter and not of the actual material and roughness of the fitting.
However if I change the material... | Solution: Aspen Flare System Analyzer includes to methods for calculating the K values, using the ft (as Crane reference) or using the actual friction factor f due to the specified material roughness. It uses the simulation-specified friction factor f by default. To use the ft as per Crane you have to go Calculation Op... |
Problem Statement: The TAILPIPE / YES option has been selected for a pipe in FlareNet. Are results for this based on nominal flow, or rated flow? | Solution: If Rated Flow For Tailpipes check box (Calculations --> Options --> General tab) is checked, results shown are based on data from both the nominal flow case, and the rated flow case.
Pressure /pressure drops are based on calculations done using rated flow. Call presure at any point in the tailpipe Pr.
Report... |
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