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Phase equilibria calculation error

2016-07-09
2016-07-11
  • Peter Stovíček

    Greetings,

    I tried to use dwsim for simulation of simple raw glycerol separation process. However I can not get through the first step which is definiton of raw glycerol stream. Once I enter the composition of stream, the input temperature and pressure, the calculation stops working, giving me the "Phase equilibria calculation error. (T = 298.15 K, P = 101,325.00 Pa, MoleFracs = { 0.256394, 0.191341, 0.540517, 0.011748, })" error.

    I am a first time user of dwsim and I tried to do everything according to the video tutorial on the wiki, but once i replace the stream compounds from the tutorial with the desired ones I keep getting this error.

    Here is attached the simulation dwxml file, but I get the error even when I try to just define the raw glycerol stream in a new simulation
    2-13600_methanol:sepraion.dwxml

    I use the v3.7 Build 5981 version.

    Thank you in advance for your help and have a nice day

     
  • Gregor Reichert

    Gregor Reichert - 2016-07-10

    Hi Peter,
    i had a look into your simulation. There are several problems you introduced:
    The component Sodium Cloride can not be handled by PengRobinson property package. Remove this.
    The PengRobinson property package probably is not suitable for the things you want to simulate. Due to the kind of components, temperatures and pressure you rather should use an activity coefficient model like ModifiedUnifac(Do). But this is not dealing with electrolytes either.
    * The heater needs to equiped with an energy stream. Now you model will calculate without problems.

    You should be aware that there is a special BioDiesel model available in DWSIM. This probably might be able to solve your problems But you should ask Daniel for further details on that.

    Gregor

     
  • Peter Stovíček

    Thank you very much for your help. After removing the electrolyte from the mixture and changing the property package it works like a charm. Electrolyte is anyway expected only to end up in the distillation bottom.

    Peter

     

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