Activity for Thubelihle
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Thubelihle posted a comment on discussion Help (Classic UI)
hi, the adjust unit is not working, and l am failing to troubleshoot. Thanks for your help. the manipulated variable variable does not affect the controlled variable when it should
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dwsim file
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table
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hi. The column does converge, but the molor flowrate of the vapour leaving stage 1 is different to the molar liquid flowrate leaving the condenser. ln a total ondenser these should balance. This then led to a reflux ratio different from the specified one.
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Hi. I attached the aspen NRTL interaction parameters. Tried to use DWSIM UNIFAC LL to estimate the parameters, but they look different as from those from aspen. l concluded that maybe they reoprt their parameters differently.
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aspen solution
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Thank you. Was wondering, used MIBK as a solvent to extract acetone from water. The MIBK is fed from the bottom of the tower and is meant to extract acetone and leave the top power as a rich solvent. The almost pure water is meant to exit the bottom of the tower. But in the simulation MIBK seems to miscible with water hence exiting also in the bottoms in large amounts. Also the extract product temperature is too high compared to one obtained from aspen
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hi, when simulating an extraction unit, should l use the simple LLE flash algorithm since only two liquid phases are involved? thanks
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files
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files
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hi. everything else is the same ie composition and temperatures of bottoms and distillate, but shortcut results, minimum and real number of stages is totally different with a large margin. NRTL was used as the property package
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attachment
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hi.i am getting negative number of stages and minimum reflux ration. kind regards.
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i see you changed the solving scheme, maximum number of iterations and IO solver settings for it to converge. How do l know what settings to change and to what value, before reaching a decision that the column can't operate to produce a certain distillate purity. Thanks
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sorry, find attached
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Haha fair enough Daniel, learning a lot though. Will make a donation. Regards
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File
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Hi. This tutorial was solved using DWSIM 4 and it converged. l am trying it on DWSIM 5 update 8 and is not converging. Wondering whats wrong l am doing? Thanks for your help.
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File
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Following a tutorial on multiple reactions using an equilibrium reactor and l am getting a basis error. Followed all the steps and l get the message: reaction basis error. l tried to use Peng Robison and still no lucky. Your help will be much appreciated. Thanks
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Thanks a lot for the source, but l have a slight knowledge of programming. Are the deductions that the values should match correct at all?
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please find attached the dwsim file
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please find attached the dwsim file
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i am solving the water gas shift reaction, using an equilibrium reactor, for some reason it says the selected basis is not supported.
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DWSIM DOC
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master table
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Table
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l analysed tray by tray compositions and tried to match that with the results from the master table and they did not match. For the condenser, l neglected the vapour composition as you suggested as it is meaningsless for a total condenser. The mole fraction from out of the condenser for hexane do not match that in the master table. Same applies to the liquid from the partial reboiler, with the assumption it is an equilibrium stage. Your help will be much appreciated.
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Hi Daniel, Thanks for all the knowledge, l am learning more each and everyday. Was wondering, since the reboiler is a partial reboiler, hence an equilibrium stage, in the above diagram [V] n-hexane = 0.9444 and [V] n- pentane = 0.0555 is the boil- up composition, and [L] n-hexane = 0.9771 and [L] n- pentane = 0.02288 is the bottoms composition. However the bottoms compositions in the master table is different from this. l attached the complete simulation. Thanks for your help.
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composition table
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For example in stage 1, is the 0.896 [V] n- pentane and 0.104 [V] n-hexane is it the vapour leaving stage 1 to the condenser and 0.749 [L] n- pentane and 0.251 [L] n-hexane liquid leaving stage 1 to stage 2. Also on the temperature table there is TO(C) and Tf(C), guessing its T initial and Tfinal; is the temperature on the stages not uniform? Thanks for your help.
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Hi, l am trying to interpret the distillation table results to no avail. Attached below is the picture of the problem.
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Hi Daniel, Thanks, did that and it balanced. In the tutorial we were given the value of k (rate constant), and no data was available for A (frequency factor) and E (activation energy). How do we go about this, since the kinetic reactor requires both A and E, and in the tutorial they used the value of k as A.
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Attached is the relevant file.
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Attached is the relevant file.
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Hi Daniel, After simulating a reactor l did a mass balance, and it balanced. How do l do energy balance for a reactor. l tried to use energy = energy out equation, but l failed and l guess its because of the consumption term. If so how do l then go about doing the energy balance. Thanks.
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Hi Daniel, Thanks a lot sir, and my bad its between 0.87 and 0.9 and agrees with literature. How do l pinpoint the exact composition? You mentioned using excel, l exported the data to excel and reproduced the xy diagram. I tried to use the treadline to no avail. Attached is the excel spreadshit. Thanks.
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xy graph
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xy graph
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xy graph
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I came up with the VLE equilibrium for the ethanol- water system at 1atm and 78*C, and use the xy data to predict the azeotropic composition, where x = y. l found that at azeotropic conditions the mole fraction of ethanol is 0.8 but literature gives a value of 0.904 at the same conditions. Attached are relevant files. Thanks
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Hi, l am reading around literature, and l found out ethanol - water system has an azeotrope at 1 atm and 78*C. At these azeotropic conditions, the mole fraction of water is 0.096. Is there anyway of using DWSIM to predict azeotropic mole fraction at different operating conditions? Say l want to increase pressure to 10 atm inorder to utilize pressure swing distallation.
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Hi Daniel, I downloaded the latest version and it solved my problem. However, the distillate and bottoms have mixed phases; even from the picture you sent me above. l used a total condenser, and l expect the bottoms and the distillate to be liquid only. Thanks
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Excel
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Attachments
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Hi, I did a shortcut distillation simulation of hexane and pentane. I did the mass and energy balance around the distillation column. The mass balance was correct, however the energy balance did not add up. My basis for the energy equation is as follows: Feed energy + Reboiler energy = Distillate energy + Bottoms energy + Condenser energy. The energy flows for the feed, distillate and bottoms are negatives, how so? Attached below is the simulation. Thanks for your help.
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Here is the file.
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Hi, l am tring to simulate a PFR given the reaction rate, k= 0.2533 mol/sm3. But...
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Hi. Thanks, l did but it retains NaCN. The mass flow and temperature are just allowable...
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Attached is the relevant file, l cannot find an object to close the loop
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hie. how do l close a cycle in a power plant as an example
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Hi. Does sulfuric acid exist in DWSIM database or l have to add it? What is meant...
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Attached are relevant files. For k inquiry see CSTR
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I am given conversion as 215.25-0.594T C, and to convert to Kelvin the expression...
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The values should be 1 and 0, since these streams do not mix in a heat exchanger....
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Hie any reason l am getting NaN for values?
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l have attached the relevant file.
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May someone explain the parameters of the flash drum for me. What is mearnt by Outlet...
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Hi, thanks for your response. How do l interpret the table. For example in stage...
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Hi. True, may l am the one messing up. The feed stream composition is as follows(mole...
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Hi, The sensitivity tool is not working in DWSIM version 4. I specify the condenser...
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Hie, How do l check vapour composition leaving the distillation still just before...
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l am still having problems with the reboiler specification in the product molar flow...
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