Binary parameters for DME and other hydrocarbons 1

[mahesh009]

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..

 

[dinu24]

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

 

[mahesh009]

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

 

[mahesh009]

Hi DInu,.

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

 

[UmeshMathur]

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.

 

[mahesh009]

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.

 

[dinu24]

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

 

[UmeshMathur]

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.

 

[dinu24]

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

 

[mahesh009]

Umesh and Dinu,

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

Thanks

 

[mahesh009]

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
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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
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THERMODYNAMIC DATA
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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

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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

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THERMODYNAMIC DATA
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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

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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
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THERMODYNAMIC DATA
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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

 

[UmeshMathur]

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.