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Gravity separator (biodiesel production process)

2016-07-20
2016-07-22
  • Sabina Tribenti

    Sabina Tribenti - 2016-07-20

    Hello everyone!
    I'm trying to simulate the biodiesel production process, and i need a couple of gravity separators to do so. Since the simulator doesn't have them in the object palette, I wanted to know if anyone has found an alternative to simulate a separation, maybe with something compatible with dwsim ?
    Thanks!!
    Sabina

     
  • Gregor Reichert

    Gregor Reichert - 2016-07-20

    Hi Sabina,
    there are several different ways to accomplish that. Depending on the way you model this you either could try:
    Solid separator
    Filter
    Component separator
    Excel-Unit-Operation
    User-Unit-Operation
    Running a script

    May be there are still some other ways.
    i hope this will help you.

    Gregor

     
    • Sabina Tribenti

      Sabina Tribenti - 2016-07-21

      Hi Gregor,
      I have two liquid streams to separate (one mainly of glycerol, the other one is a mix of fatty acid methyl esters), so I can't use the solid separator. I've tried the component one, but it appears that it doesn't calculate the concentrations in the outlet streams as the one in the equilibrium, but it asks wich ones i want. Since there's no experimental data about this (at least not that i was able to find), i can't calculate and introduce them later.
      I'll try to do the excel-unit-operation.
      Thanks!!
      Sabina

       

      Last edit: Sabina Tribenti 2016-07-21
  • Gregor Reichert

    Gregor Reichert - 2016-07-22

    Hi Sabina,
    the biodiesel simulation you intend to do seems to be possible straight away. There is a special biodiesel component database implemented in DWSIM already. There are components like "PPP", "PPO", ...
    You select "NRTL" as property package and "NestedLoops(VLLE)" as flash procedure. DWSIM already comes with a special Biodiesel-NRTL-Interaction-Parameter-Database.

    If you configure your simulation this way, you will find that the stream contains two liquid phases. This stream may be fed into a phase separator where both liquid outlets are attached to as stream. Each liquid outlet will contain one phase.

    I am not an expert in biodiesel production, therefore you have to figure out what the naming convention of these components (e.g. PPP) do mean.

    I never did a simulation with theses components. It will be interesting to get informed about your experiences.

    Gregor

     
  • Daniel Medeiros

    Daniel Medeiros - 2016-07-22

    For the naming conventions:

    A biodiesel simulation in DWSIM must be done with the NRTL Property Package. The Biodiesel-NRTL interaction parameters were taken from a MSc thesis from a friend of mine (I don't have the reference link right now and it is in portuguese anyway). I don't know if the parameters predict liquid phase split.

    You'd better have some experimental data regarding this gravity separator, otherwise you'll have to use the component separator with some kind of separation efficiency. Rigorously, you would use the experimental data to regress NRTL parameters capable of predicting liquid phase split. This would be the most correct way of simulating the separator.

     
  • Gregor Reichert

    Gregor Reichert - 2016-07-22

    I already checked that a mixture of Glycerol and PPP are splitting into two liquid phases. One phase contains nearly pure PPP and the other a mixture of glycerol/PPP with 75 mol% of glycerol.

    The only problem i encountered is that DWSIM has a problem still to calculate the separator vessel.

     
    • Daniel Medeiros

      Daniel Medeiros - 2016-07-22

      Enthalpy balance? This may be easier to fix then... :-)

       

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