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#251 Wet Gas separation: Different outputs with VLE and VLLE Flash algos.

5.8
open
Daniel Medeiros
None
2020-07-21
2019-12-05
Sameer Ningoo
No

  1. The gas-liq separator gives different flows of the HC liquid and water when run with VLE and with VLLE Flash algortihm for the same amount of inlet wet gas flow (51948kg/h)
    with VLE - the HC liq condensate flow is 10978 kg/hr (water flow is 0k/hr)
    but with VLLE- the water flow is 389 kg/hr and Condensate flow is 2985kg/hr
    THE HYSYS output gives a HC liq condensate flow of 3152kg/hr and water flow of 3152kg/hr.

  2. With VLLE- the Separation gives a heat output of 1238KW? The input wet gas temp is 85--but the HC liq. condensate and water temp is 75C and output gas is 82C. Also the output gas has mixed phases and is not saturated. All input and output streams of separatro should have same temp like in HYSYS

  3. With VLE Flash algoritm- the Separation gives the same heat output of 1238KW. The The input wet gas temp is 85--but the HC liq. condensate and water temp is 61C and output gas is 88C. Also the output gas has mixed phases(0.96 vapour). All input and putput streams of separatro should have same temp.

Have atached the DWSIM file.

1 Attachments
VLE_VLLE_wetgas separation.dwxmz

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Discussion

  • Sameer Ningoo

    Sameer Ningoo - 2019-12-05
    • Description has changed:

    Diff:

    --- old
+++ new
@@ -1,4 +1,4 @@
-1.The gas-liq separator gives different flows of the HC liquid and water when run with VLE and with VLLE Flash algortihm for the same amount of inlet wet gas flow (51948kg/h)
+1. The gas-liq separator gives different flows of the HC liquid and water when run with VLE and with VLLE Flash algortihm for the same amount of inlet wet gas flow (51948kg/h)
 with VLE - the HC liq  condensate flow is 10978 kg/hr (water flow is 0k/hr)
 but with VLLE- the water flow is 389 kg/hr and Condensate flow is 2985kg/hr 
 THE HYSYS output gives a HC liq condensate  flow of 3152kg/hr and water flow of 3152kg/hr.
     

  • Daniel Medeiros

    Daniel Medeiros - 2019-12-05

    THE HYSYS output gives a HC liq condensate flow of 3152kg/hr and water flow of 3152kg/hr.

    are the mass flows the same for both streams in HYSYS?

     

    Last edit: Daniel Medeiros 2019-12-05

  • Sameer Ningoo

    Sameer Ningoo - 2019-12-05

    I am sorry for typo- with HYSYS the HC Liq condensate flow is 2890kg/hr and water flow is 3152kg/hr.

     

  • Daniel Medeiros

    Daniel Medeiros - 2020-05-18

    In the upcoming v6 release, although the mass flow balance is correct, the streams do not leave the separator in the saturation state. It seems that the VLLE flash result is not 100% correct. Also, the PR EOS has difficulties on calculating the compressibility factors for the liquid phases at the specified conditions, hence the inconsistencies. I've noticed that you did not defined a value for the missing interaction parameters, which is not an issue on HYSYS. That could probably help.

     

  • Daniel Medeiros

    Daniel Medeiros - 2020-05-18

    Also, by definition, if you use the VLE algorithm, you will not see two liquid phases at the separator outlet.

     

  • Daniel Medeiros

    Daniel Medeiros - 2020-05-18

    If you're not interested on mutual water/HC solubility, you can use the Immiscible VLLE flash algorithm, setting Water as the immiscible compound. That's what I do in my projects, similar to yours.

     

    Last edit: Daniel Medeiros 2020-05-18

  • Rizwan

    Rizwan - 2020-07-21

    Hello

    Thank you in advance Daniel for your help. I seem to be getting stuck at the very begining of my process which is separation. I have oil, gas and water coming in to a separator. For this three phase separator, I am expecting to have some flow rate on the heavy liquid stream. But it shows "0" on the mass flow. I have been trying different flash algorithms but it is not working. Can you please assist and tell me what I am doing wrong? Attached is the file I was working with.

     
    separation_trial.dwxmz

    • Daniel Medeiros

      Daniel Medeiros - 2020-07-21

      I've tried your simulation with Nested Loops VLLE and it worked right away.

       

      • Rizwan

        Rizwan - 2020-07-21

        Thank you very much. Yes, it worked for me now.

        On Tue, Jul 21, 2020 at 9:43 AM Daniel Medeiros danwbr@users.sourceforge.net wrote:

        I've tried your simulation with Nested Loops VLLE and it worked right away.

        Status: open
        Version: 5.8
        Created: Thu Dec 05, 2019 11:26 AM UTC by Sameer Ningoo
        Last Updated: Tue Jul 21, 2020 03:39 PM UTC
        Owner: Daniel Medeiros
        Attachments:

        -

        VLE_VLLE_wetgas separation.dwxmz
        https://sourceforge.net/p/dwsim/tickets/251/attachment/VLE_VLLE_wetgas%20separation.dwxmz
        (95.4 kB; application/octet-stream)
        -

        The gas-liq separator gives different flows of the HC liquid and water
        when run with VLE and with VLLE Flash algortihm for the same amount of
        inlet wet gas flow (51948kg/h)
        with VLE - the HC liq condensate flow is 10978 kg/hr (water flow is
        0k/hr)
        but with VLLE- the water flow is 389 kg/hr and Condensate flow is
        2985kg/hr
        THE HYSYS output gives a HC liq condensate flow of 3152kg/hr and water
        flow of 3152kg/hr.
        -

        With VLLE- the Separation gives a heat output of 1238KW? The input wet
        gas temp is 85--but the HC liq. condensate and water temp is 75C and output
        gas is 82C. Also the output gas has mixed phases and is not saturated. All
        input and output streams of separatro should have same temp like in HYSYS
        -

        With VLE Flash algoritm- the Separation gives the same heat output of
        1238KW. The The input wet gas temp is 85--but the HC liq. condensate and
        water temp is 61C and output gas is 88C. Also the output gas has mixed
        phases(0.96 vapour). All input and putput streams of separatro should have
        same temp.

        Have atached the DWSIM file.

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        --
        Rizwan Al-Rahman
        Project Mechanical and Process Engineer, P.Eng.

         

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        Tickets (Inactive): #251

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