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Binary parameters for DME and other hydrocarbons

Binary parameters for DME and other hydrocarbons

Binary parameters for DME and other hydrocarbons

(OP)
Hi All,

 I couldn't find binary interaction parameters for DME with water and other hydrocarbons in simulators such as HYSYS,PRO/II and Aspen plus.How can i get those parameters?
My process is to separate DME from mixture of hydrocarbons(c3-c9) and water. My objective is to recycle DME from the effluents of MTBE and TAME unit in the refinery process. Appreciate your help guys..

RE: Binary parameters for DME and other hydrocarbons

Hi Mahesh;

You are looking for binary interaction parameters for what equations? They could be different for each Equations of State. If you are using activity coeff methods (which you may not be) then they are different for those too. In any case, you will be able to get some info from the DECHEMA, escpecially for PR and SRK EOS.


-Dinu

http://www.dinu.biz

RE: Binary parameters for DME and other hydrocarbons

(OP)
Thanks for your advice.HYSYS and PRO/II do not have any interaction parameters for DME with methanol,ethanol ropane,propene,butane,butene etc.. for any EOS like NRTL,SRK,UNIQUAC or Wilson. Can u plz guide me..

Thanks
Mahesh

RE: Binary parameters for DME and other hydrocarbons

(OP)
Hi DInu,.

I dun have DECHEMA software. Is there any alternate way to get these parameters?

RE: Binary parameters for DME and other hydrocarbons

First, Dinu24 is mistaken in suggesting use of the PR or SRK equations of state for such systems.  These are highly non-ideal liquid phases that require use of activity coefficient models such as Wilson, NRTL, or UNIQUAC.  By the way, Wilson cannot handle liquid phase immiscibility whereas NRTL and UNIQUAC can.  NRTL requires 3 binary interaction parameters per binary, whereas UNIQUAC requires only 2.  I prefer UNIQUAC for a variety of theoretical and practical reasons.

Second, if the interaction parameters are not available in the DECHEMA data books, you likely need to use the UNIFAC group contribution method to estimate the two infinite dilution activity coefficients per binary pair of components.  From these, you can determine the activity coefficient parameters for your chosen model.

If using the published DECHEMA parameters, be careful to check their vapor pressures against what you are using.  Also, for some binaries where there are multiple sets of VLE data, they report different interaction parameters for each set.  Ideally, you should then combine all the reported VLE data for a given binary system and regress the activity coefficient parameters yourself.  Bad data points can be diagnosed easily, thrown out, and the regressions repeated until you have a good fit across the range of P-T-X-Y.

Have fun.

RE: Binary parameters for DME and other hydrocarbons

(OP)
Thanks a  lot Mathur.
HOw can i get DECHEMA published data? Can I use Henry's Liquid activity parameters to the solutes present in the hydrocarbon mixture?. In PRO/II, after selecting NRTL package, I went in to modify data n then clicked enter tab to check for any solutes. It has shown butane,butene,pentane,mathanol.ethanol and DME as solutes. So, i have checked Henry's liquid activity coefficient box. When I simulated using above method, I got 97% recovery along with butane, butene, Trans-2-butene, methanol ,water and DME. I have to separate DME from the rest using a distillation unit. Plz suggest me if u have nay ideas. Especially i would like to know abt DECHEMA data and regression of the parameters.

RE: Binary parameters for DME and other hydrocarbons

Thanks for correcting me, UmeshMathur. Just wondering though, when you say "Bad data points can be diagnosed easily, thrown out, and the regressions repeated until you have a good fit across the range of P-T-X-Y" are you suggesting that one just scan the data curve and see what is physically unlikely?, or base the judgement on experience?, to decide which is a bad data point and which is not?

I have investigated a regression algorithm for Wilsons, and looked at Nishumi's paper on BIP for PR EOS, which are both based on the infinite dilution technique to reduce the number of unknowns. I am guessing that should hold good for NRTL too although we are looking at one more interaction parameter.

Mahesh009;
I have struggled to get NRTL parameters in the past. In most cases I got the parameters off of research papers. I dont have Aspen Properties, the physical property gateway from Aspen Technologies, installed on my machine, but I believe you can get the parameters, estimated or not, from the program. I am not sure, but I have not found too much from DECHEMA for NRTL.

http://www.dinu.biz

RE: Binary parameters for DME and other hydrocarbons

Hi, mahesh009:
(1) The definitive book on how to handle such systems is J. M. Praunitz, et al: "Computer Calculations for Multicomponent Vapor-Liquid and Liquid-Liquid Equilibria" (Prentice-Hall, 1980).  I strongly suggest a study of this material or consultation with in-house thermodynamicists before you do work of any commercial significance.

The commercial simulators you have mentioned all allow use of activity coefficient models for the main polar components (DME, methanol, ethanol, water) and at least two of them allow use of the "unsymmetric" convention to compute gas component solubility in the liquid phase.  This issue is also discussed in the reference cited above.

The DECHEMA VLE data is contained in a large number of volumes available in most engineering libraries.  These expensive books are organized by molecular types.

For binary mixtures for which no VLE data is available, I would recommend approximation of the VLE using the UNIFAC group contribution method.  This should also be readily available in the simulators you mentioned.  The UNIFAC method is described in J.M. Prausnitz, et al: "Molecular Thermodynamics of Fluid Phase Equilibria" (3rd Edition, Prentice-Hall PTR, 1999).

All this material does not make for the easiest reading, but is well worth the effort.  As you might suspect, a good graduate course in thermodynamics usually encompasses all these subjects nicely.

dinu24:
I appreciate your taking my remarks in the proper spirit, as they were designed to be instructive rather than critical.

Regarding the question of VLE data analysis, my method is simply to regress ALL P-T-X-Y data simultaneously against the selected thermodynamic model and compare calculated v/s experimental values.

If using Barker's method with P-X data - see Smith, van Ness, and Abbott: "Chemical Engineering Thermodynamics", (6th Ed., McGraw-Hill, 2001) -  T and Y are not used at all in the nonlinear regression.  The mismatch in the T and Y values is a good indication of two important criteria:
(a) Does the selected thermo model do a good job matching the data, i.e., is there a systematic deviation in the prediction errors for T and Y?, and
(b) Are there any really inaccurate data points ("outliers") that are skewing the model parameters unduly and, therefore, need to be deleted.  Note that I never throw out bad data arbitrarily or by guesswork.

If using the maximum likelihood method (described in the first Prausnitz reference above), all P-T-X-Y values are used in the regression.  However, the data can still be examined against the same two criteria.

For systems with a very large temperature range, the regressed NRTL/UNIQUAC/Wilson parameters may need to be made a function of temperature in the regression, as the temperature dependence built in to these models may not be adequate.  This issue is discussed nicely in the second Prausnitz reference cited above.

Another cautionary note:  even though the DECHEMA books list regressed interaction parameters, I would strongly recommend re-regressing the combined VLE data using your simulator's built-in pure component properties, mainly vapor pressure.  Discrepancies in pure component properties against DECHEMA do exist and could lead to catastrophic computing errors: For some binaries, there are instances in DECHEMA where entirely different Antoine equation vapor pressure constants have been used for regressing VLE data sets from different literature sources.  Which of the published set of such parameters should you use?  My answer is NONE.  Instead, you ought to combine all the data and perform a single regression to get the best binary parameter values, using your simulator's vapor pressure equations, liquid molar volumes, or UNIQUAC r and q parameters as appropriate.

Finally, there is also a DECHEMA data book listing measured infinite-dilution activity coefficients.  These can be used to compute reliably the binary interaction parameters for the chosen activity coefficient model.

RE: Binary parameters for DME and other hydrocarbons

UmeshMathur;
Thank you very much for all the info. I'll surely check the references out. Thanks for taking the trouble, I appreciate it.:)

-Dinu

http://www.dinu.biz

RE: Binary parameters for DME and other hydrocarbons

(OP)
Umesh and Dinu,

Thanks a lot for the valuable information. Tanks for the efforts u put in to gather information. I appreciate..

Thanks

RE: Binary parameters for DME and other hydrocarbons

(OP)
I have regressed VLE data and obtained Binary parameters of DME with other HC's. I have simulated well using a short cut distillation unit and used those parameters to design a distillation column. Inspite of changing Feed stages,No of stages and reflux, it is not converging. Damping factor is less than 0.04. The input file wiht thermodynaimic data for this is
Generated by PRO/II Keyword Generation System <version 7.1>
$ Generated on: Mon Sep 25 21:47:03 2006
TITLE
  PRINT INPUT=COMPONENT,THERMO,SEQUENCE,REFP, STREAM=ALL, RATE=M, &
         FRACTION=M, ION=NONE
  SEQUENCE SIMSCI
COMPONENT DATA
  LIBID 1,METHANE/2,ETHANE/3,PROPANE/4,IBUTANE/5,BUTANE/6,IPENTANE/ &
        7,PENTANE/8,METHANOL/9,ETHYLENE/10,PROPENE/11,1BUTENE/ &
        12,IBUTENE/13,T2BUTENE/14,H2O/15,DME, BANK=PROCESS,SIMSCI
THERMODYNAMIC DATA
  METHOD SYSTEM=UNIQ, SET=UNIQ01, DEFAULT
    KVAL(VLE) FILL=UNIF, AZEOTROPE=SIMSCI
      UNIQUAC 5,15,116.662,-8.66741
      UNIQ4 3,15,6434.6,6189.88,-18,-20
      UNIQ4 10,15,6517.79,6114.88,-18,-20
      UNIQ4 15,12,-380.343,791.617,0.739904,-1.7408
STREAM DATA
  PROPERTY STREAM=GAS2, TEMPERATURE=137, PRESSURE=280, PHASE=M,  &
        RATE(M)=337.4, COMPOSITION(M)=1,0.1446/2,0.0584/3,0.4856/ &
        4,0.0531/5,0.0001/9,0.0036/10,0.2269/11,0.0001/12,0.0002/ &
        15,0.0274
  PROPERTY STREAM=GAS1, TEMPERATURE=137, PRESSURE=280, PHASE=M,  &
        RATE(M)=99.4097, COMPOSITION(M)=1,0.0006/2,0.0005/3,0.3804/ &
        4,0.09576/5,0.00727/6,9.999E-5/8,0.0026/10,0.3949/11,0.02615/ &
        12,0.00065/13,0.02337/15,0.0677
UNIT OPERATIONS
  MIXER UID=M1
      FEED GAS1,GAS2
      PRODUCT  M=MIXEROUT
  COLUMN UID=T1
      PARAMETER TRAY=75,IO=200
      FEED MIXEROUT,40
      PRODUCT  BTMS(M)=S2, OVHD(M)=S1,389, SUPERSEDE=ON
      CONDENSER TYPE=PART, PRESSURE=250
      DUTY  1,1,,CONDENSER
      DUTY  2,75,,REBOILER
      PSPEC PTOP=200
      PRINT PROPTABLE=PART, ITERATION=ALL, PROFILE=NONE
      ESTIMATE MODEL=SIMPLE, RRATIO=10
      SPEC ID=COL1SPEC1, STREAM=S2, RATE(LBM/H), COMP=15,WET, &
                 VALUE=15.97
      SPEC ID=COL1SPEC2, RRATIO, VALUE=0.8
      VARY DNAME=CONDENSER,REBOILER
      REBOILER TYPE=KETTLE
END

 SIMULATION SCIENCES INC.          R                                   PAGE R-1
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
                 VLE UNIFAC STRUCTURAL GROUPS FOR SET 'UNIQ01'
 
 COMPONENT STRUCTURAL COMPOSITION
 
 COMP      GROUP        GROUP        GROUP
 ----   ----------   ----------   ----------
    1   2011(   1)
    2    900(   2)
    3    900(   2)    901(   1)
    4    900(   3)    902(   1)
    5    900(   2)    901(   2)
    6    900(   3)    901(   1)    902(   1)
    7    900(   2)    901(   3)
    8   1611(   1)
    9   2488(   1)
   10   1100(   1)    900(   1)
   11   1100(   1)    901(   1)    900(   1)
   12   1102(   1)    900(   2)
   13   1101(   1)    900(   2)
   14   1622(   1)
   15    600(   1)    900(   1)
 
 
 INDIVIDUAL GROUP PARAMETERS
 
 GROUP         AREA      VOLUME
 -----     --------    --------
   600       1.0880      1.1450
   900       0.8480      0.9011
   901       0.5400      0.6744
   902       0.2280      0.4469
  1100       1.1760      1.3454
  1101       0.8670      1.1167
  1102       0.9880      1.1173
  1611       1.4320      1.4311
  1622       1.4000      0.9200
  2011       1.1520      1.1239
  2488       1.4880      1.5742
 
 
 MAIN GROUP INTERACTION PARAMETERS
 
   M    N        A(M,N)        A(N,M)
  ---  ---   ----------    ----------
   60   90      83.3600      251.5000
   60  110      26.5100      214.5000
   60  161     238.4000     -128.6000
   60  162    -314.7000      540.5000
   60  201       0.0000        0.0000
   90  110      86.0200      -35.3600
   90  161     697.2000       16.5100
   90  162    1318.0000      300.0000
   90  201       0.0000        0.0000

 SIMULATION SCIENCES INC.          R                                   PAGE R-2
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
             VLE UNIFAC STRUCTURAL GROUPS FOR SET 'UNIQ01'  (Cont)
 
   M    N        A(M,N)        A(N,M)
  ---  ---   ----------    ----------
  110  161     787.6000      -12.5200
  110  162     270.6000      496.1000
  110  201       0.0000        0.0000
  161  162    -181.0000      289.6000
  161  201       0.0000        0.0000
  162  201       0.0000        0.0000
 
  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
 
                        COMPONENT DATA FOR SET 'UNIQ01'
 
 COMPONENT DATA FOR THE UNIQUAC METHOD
 
 COMP         AREA      VOLUME
 ----     --------    --------
    1       1.1520      1.1239
    2       1.6960      1.8022
    3       2.2360      2.4766
    4       2.7720      3.1502
    5       2.7760      3.1510
    6       3.3120      3.8246
    7       3.3160      3.8254
    8       1.4320      1.4311
    9       1.4880      1.5742
   10       2.0240      2.2465
   11       2.5640      2.9209
   12       2.6840      2.9196
   13       2.5630      2.9189
   14       1.4000      0.9200
   15       1.9360      2.0529
 
  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
 
               VLE LIQUID INTERACTION PARAMETERS FOR SET 'UNIQ01'
 
 UNIQUAC BINARY COEFFICIENTS
 
    I   J      A(I,J)      A(J,I)    B(I,J)    B(J,I)     UNITS FROM
  --- --- ----------- ----------- --------- --------- --------- ----
    1   2     -6.9499      7.1356    0.0000    0.0000     DEG K UNIFAC
    1   3     -7.3461      7.5538    0.0000    0.0000     DEG K UNIFAC
    1   4     -8.5484      8.8307    0.0000    0.0000     DEG K UNIFAC
    1   5     -8.5525      8.8351    0.0000    0.0000     DEG K UNIFAC
    1   6     -9.0691      9.3873    0.0000    0.0000     DEG K UNIFAC
    1   7     -9.0731      9.3916    0.0000    0.0000     DEG K UNIFAC
    1   8     -6.8244      7.0035    0.0000    0.0000     DEG K UNIFAC
    1   9     -6.8447      7.0249    0.0000    0.0000     DEG K UNIFAC
    1  10    -50.4048     50.4045    0.0000    0.0000     DEG K UNIFAC
    1  11    -53.1501     53.1492    0.0000    0.0000     DEG K UNIFAC

 SIMULATION SCIENCES INC.          R                                   PAGE R-3
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
           VLE LIQUID INTERACTION PARAMETERS FOR SET 'UNIQ01'  (Cont)
 
    I   J      A(I,J)      A(J,I)    B(I,J)    B(J,I)     UNITS FROM
  --- --- ----------- ----------- --------- --------- --------- ----
    1  12    -53.2250     53.2247    0.0000    0.0000     DEG K UNIFAC
    1  13    -52.8029     52.8027    0.0000    0.0000     DEG K UNIFAC
    1  14     -6.8146      6.9932    0.0000    0.0000     DEG K UNIFAC
    1  15    -53.8010      1.3444    0.0000    0.0000     DEG K UNIFAC
    2   3    -10.9925     11.2824    0.0000    0.0000     DEG K UNIFAC
    2   4    -11.3376     11.6461    0.0000    0.0000     DEG K UNIFAC
    2   5    -11.3408     11.6495    0.0000    0.0000     DEG K UNIFAC
    2   6    -11.7941     12.1281    0.0000    0.0000     DEG K UNIFAC
    2   7    -11.7979     12.1321    0.0000    0.0000     DEG K UNIFAC
    2   8    697.2000     16.5100    0.0000    0.0000     DEG K UNIFAC
    2   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    2  10     46.9172    -27.1440    0.0000    0.0000     DEG K UNIFAC
    2  11     36.2019    -23.2784    0.0000    0.0000     DEG K UNIFAC
    2  12     28.5238    -19.8834    0.0000    0.0000     DEG K UNIFAC
    2  13     26.0473    -18.6585    0.0000    0.0000     DEG K UNIFAC
    2  14   1318.0000    300.0000    0.0000    0.0000     DEG K UNIFAC
    2  15    120.2274     -3.7517    0.0000    0.0000     DEG K UNIFAC
    3   4    -13.2423     13.5898    0.0000    0.0000     DEG K UNIFAC
    3   5    -13.2437     13.5912    0.0000    0.0000     DEG K UNIFAC
    3   6    -13.5005     13.8616    0.0000    0.0000     DEG K UNIFAC
    3   7     89.9039   -103.5080    0.0000    0.0000     DEG K SIMSCI VLEBANK
    3   8    697.2000     16.5100    0.0000    0.0000     DEG K UNIFAC
    3   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    3  10     46.4426    -27.0944    0.0000    0.0000     DEG K UNIFAC
    3  11     35.6893    -23.1653    0.0000    0.0000     DEG K UNIFAC
    3  12     28.0456    -19.7268    0.0000    0.0000     DEG K UNIFAC
    3  13     25.5917    -18.4942    0.0000    0.0000     DEG K UNIFAC
    3  14   1318.0001    300.0000    0.0000    0.0000     DEG K UNIFAC
    3  15   6434.5957   6189.8755  -18.0000  -20.0000     DEG K INPUT
    4   5    105.1770    -93.3399    0.0000    0.0000     DEG K SIMSCI VLEBANK
    4   6    -14.5827     14.9645    0.0000    0.0000     DEG K UNIFAC
    4   7    -14.5836     14.9655    0.0000    0.0000     DEG K UNIFAC
    4   8    697.2000     16.5100    0.0000    0.0000     DEG K UNIFAC
    4   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    4  10     46.4503    -27.1011    0.0000    0.0000     DEG K UNIFAC
    4  11     35.4606    -23.1140    0.0000    0.0000     DEG K UNIFAC
    4  12     27.8312    -19.6539    0.0000    0.0000     DEG K UNIFAC
    4  13     25.3898    -18.4202    0.0000    0.0000     DEG K UNIFAC
    4  14   1318.0001    300.0000    0.0000    0.0000     DEG K UNIFAC
    4  15    117.3875     -2.5750    0.0000    0.0000     DEG K UNIFAC
    5   6    -15.1897     15.5874    0.0000    0.0000     DEG K UNIFAC
    5   7    187.0540   -105.7780    0.0000    0.0000     DEG K SIMSCI VLEBANK
    5   8    675.2230    -11.1010    0.0000    0.0000     DEG K SIMSCI VLEBANK
    5   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    5  10     46.4504    -27.1012    0.0000    0.0000     DEG K UNIFAC
    5  11    -71.0529     85.7791    0.0000    0.0000     DEG K SIMSCI VLEBANK
    5  12     27.7828    -19.6374    0.0000    0.0000     DEG K UNIFAC
    5  13     25.3103    -18.3901    0.0000    0.0000     DEG K UNIFAC
    5  14   1318.0000    300.0000    0.0000    0.0000     DEG K UNIFAC

 SIMULATION SCIENCES INC.          R                                   PAGE R-4
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
           VLE LIQUID INTERACTION PARAMETERS FOR SET 'UNIQ01'  (Cont)
 
    I   J      A(I,J)      A(J,I)    B(I,J)    B(J,I)     UNITS FROM
  --- --- ----------- ----------- --------- --------- --------- ----
    5  15    116.6622     -8.6674    0.0000    0.0000     DEG K INPUT
    6   7     -0.2802      0.2803    0.0000    0.0000     DEG K UNIFAC
    6   8    776.9180    -24.0951    0.0000    0.0000     DEG K SIMSCI VLEBANK
    6   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    6  10     46.4566    -27.1066    0.0000    0.0000     DEG K UNIFAC
    6  11     35.4030    -23.1028    0.0000    0.0000     DEG K UNIFAC
    6  12     27.7836    -19.6379    0.0000    0.0000     DEG K UNIFAC
    6  13     25.2974    -18.3866    0.0000    0.0000     DEG K UNIFAC
    6  14   2931.0801   -415.8260   -5.3112    3.3761     DEG K SIMSCI LLEBANK
    6  15    117.6403     -2.7646    0.0000    0.0000     DEG K UNIFAC
    7   8    914.2320     -9.2837    0.0000    0.0000     DEG K SIMSCI VLEBANK
    7   9     86.0200    -35.3600    0.0000    0.0000     DEG K UNIFAC
    7  10     46.4566    -27.1066    0.0000    0.0000     DEG K UNIFAC
    7  11     35.4030    -23.1028    0.0000    0.0000     DEG K UNIFAC
    7  12     27.7840    -19.6383    0.0000    0.0000     DEG K UNIFAC
    7  13     25.2974    -18.3866    0.0000    0.0000     DEG K UNIFAC
    7  14   3371.3000   -345.5840   -6.8027    3.2116     DEG K SIMSCI LLEBANK
    7  15    117.6439     -2.7720    0.0000    0.0000     DEG K UNIFAC
    8   9    -12.5200    787.6000    0.0000    0.0000     DEG K UNIFAC
    8  10     14.6421    608.4010    0.0000    0.0000     DEG K SIMSCI VLEBANK
    8  11     -8.4187    729.5234    0.0000    0.0000     DEG K UNIFAC
    8  12    -35.3764    706.2720    0.0000    0.0000     DEG K SIMSCI VLEBANK
    8  13     -4.0818    719.0722    0.0000    0.0000     DEG K UNIFAC
    8  14   -158.0230     76.5807    0.0842    0.3344     DEG K SIMSCI VLEBANK
    8  15    348.7880     25.1000    0.0000    0.0000     DEG K SIMSCI VLEBANK
    9  10    -18.8895     25.4156    0.0000    0.0000     DEG K UNIFAC
    9  11    -23.5626     35.1040    0.0000    0.0000     DEG K UNIFAC
    9  12    -26.6842     43.1321    0.0000    0.0000     DEG K UNIFAC
    9  13    -27.6451     45.9586    0.0000    0.0000     DEG K UNIFAC
    9  14    270.6000    496.1000    0.0000    0.0000     DEG K UNIFAC
    9  15    107.1758    -17.6542    0.0000    0.0000     DEG K UNIFAC
   10  11     -6.7949      7.5092    0.0000    0.0000     DEG K UNIFAC
   10  12    -11.4939     13.7315    0.0000    0.0000     DEG K UNIFAC
   10  13    -12.9855     15.9250    0.0000    0.0000     DEG K UNIFAC
   10  14    403.8943    398.9530    0.0000    0.0000     DEG K UNIFAC
   10  15   6517.7891   6114.8809  -18.0000  -20.0000     DEG K INPUT
   11  12     -5.2969      5.7220    0.0000    0.0000     DEG K UNIFAC
   11  13     -6.9191      7.6722    0.0000    0.0000     DEG K UNIFAC
   11  14    487.5779    375.3463    0.0000    0.0000     DEG K UNIFAC
   11  15    110.9628    -19.8133    0.0000    0.0000     DEG K UNIFAC
   12  13     -1.0725      1.1187    0.0000    0.0000     DEG K UNIFAC
   12  14    547.1414    358.3913    0.0000    0.0000     DEG K UNIFAC
   12  15    791.6172   -380.3431   -1.7408    0.7399     DEG K INPUT
   13  14    576.3408    353.2243    0.0000    0.0000     DEG K UNIFAC
   13  15    111.7513    -16.7443    0.0000    0.0000     DEG K UNIFAC
   14  15    380.3438   -163.7004    0.0000    0.0000     DEG K UNIFAC

 SIMULATION SCIENCES INC.          R                                   PAGE R-5
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
                THERMODYNAMIC SETS USED FOR EACH UNIT OPERATION
 
 DEFAULT METHOD IS UNIQ01
 
 THERMODYNAMIC SET   UNIT OPERATIONS
 -----------------   ---------------
 UNIQ01              M1, T1
 
 UNIT IDENTIFIER     UNIT OPERATION                THERMODYNAMIC SET
 ---------------     --------------                -----------------
 M1                  MIXER                         UNIQ01
 T1                  COLUMN                        UNIQ01

 SIMULATION SCIENCES INC.          R                                   PAGE R-6
 PROJECT                     PRO/II  VERSION 7.1 ELEC V6.6                     
 PROBLEM                                 INPUT                                 
                                   THERMODYNAMIC DATA                          
 ==============================================================================
 
                    THERMODYNAMIC METHODS USED FOR EACH SET
 
 THERMODYNAMIC SET        UNIQ01 (DEFAULT)
 
   PROPERTY               METHOD
   --------               ------
   KVALUE(VLE)            UNIQUAC
   KVALUE(LLE)            UNSPECIFIED
   KVALUE(SLE)            UNSPECIFIED
   LIQUID ENTHALPY        IDEAL
   VAPOR  ENTHALPY        IDEAL
   LIQUID DENSITY         IDEAL
   VAPOR  DENSITY         IDEAL
   LIQUID ENTROPY         UNSPECIFIED
   VAPOR  ENTROPY         UNSPECIFIED
   LIQUID VISCOSITY       UNSPECIFIED
   VAPOR  VISCOSITY       UNSPECIFIED
   LIQUID CONDUCTIVITY    UNSPECIFIED
   VAPOR  CONDUCTIVITY    UNSPECIFIED
   SURFACE TENSION        UNSPECIFIED
   FUGACITY               IDEAL
   HENRY                  UNSPECIFIED
   LIQUID DIFFUSIVITY     UNSPECIFIED
My objective here is to separate DME and butanes  from Propanes in first column and then recover DME as overhead product from second column.
Plz suggest me if i have done anything wrong.

Thanks

RE: Binary parameters for DME and other hydrocarbons

mahesh009:

At first glance, it appears that:

(1) Your column overhead pressure is lower than the condenser which would be a simulation error.  Secondly, you have not specified a column pressure drop.

(2) To start things off, I recommend you use a simpler specification for the bottoms stream, e.g., a total stream flow rather than a component flow.  I generally use a distillate flow plus reflux ratio spec in the early runs.

(3) As a rule, you should provide decent temperature guesses for the condenser, overhead, feed stage, and reboiler based on what you are trying to accomplish.

Try making these changes and let us know what happens.  If you still have problems, I'll try to look into this in more detail within a day or two.

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