584 Ind. Eng. Chem. Process Des. Dev. 1986, 25, 584-589

Provder, T., Ed. "Size Exclusion Chromatography. Methodology and Charac- terization of Polymers and Related Materlals"; Amerlcan Chemlcal Socle- ty: Washlngton, DC, 1984; ACS Symp. Ser. No. 245.

Ramachandran, P. A.; Chaudhari, R. V. "Three Phase Catalytic Reactors"; Gordon and Breach London, 1984; Chapter 3.

Ray, W. H.; Laurence, R. L. I n "Chemical Reactor Theory-A Review"; La- pldus, L., Amundson, N. R., Eds.; Prentice-Hall: Englewood Cllffs, NJ, 1977; Chapter 9.

Ray, W. H. I n "Chemical Reactlon Englneerlng-Plenary Lectures"; Wei, J., Georgakis, C., Eds.; American Chemlcal Society: Washlngton, DC 1983; ACS Symp. Ser. No. 226, pp 101-133.

Robertson, A. B.; Cook, J. A.; Gregory, J. T. I n "Polymerization Klnetlcs and Technology"; Platzer, N. A. J., Ed.; Amerlcan Chemical Soclety: Wash- ington, DC, 1973; Adv. Chem. Ser. No. 128, pp 258-273.

Schnell, H. "Chemistry and Physics of Polycarbonates"; Interscience: New York, 1964.

Schugerl, K.; Dimian, A. L. Chem. Eng. Sci. 1080, 35, 963. Slade, P. E., Ed. "Polymer Molecular Weights"; Marcel Dekker: New York.

1975; Part 11.

Tsoukas, A.; Tirrell, M.; Stephanopoulos, G. Chem. Eng. Sci. 1982, 3 7 ,

Uirich, H. "Introductlon to Industrial Polymers"; Macmlllan: New York, 1982. Vernaieken, H. I n "Interfacial Synthesis"; MllHch, F., Carraher, C. E., Jr.,

Eds., Marcel Dekker: New York, 1977; Vol. 11, Chapter 13, pp 65-121. Villermaux, J.; Blavier, L. Chem. Eng. Sci. 1084, 39, 87. Wielgosz, 2.: Dobkowski, 2.; Krajewskl, B. Eur. folym. J. 1072, 8, 1113.

1785.

Received for review April 29, 1985 Revised manuscript received September 26, 1985

Accepted October 13, 1985

Supplementary Material Available: Detailed equations associated with various cases cited in the text (21 pages). Ordering information is given on any current masthead page.

Multicomponent Vapor-Liquid Equilibria Measurements for the Development of an Extractive Distillation Process for the Processing of Gas Issuing from a COJEOR Project

Jane H. Hong and Rikl Kobayashl"

Department of Chemical Engineering, Rice Universlty, Houston, Texas 7725 1

This paper presents V-L-E data for a multicomponent C02-rich gas added to n-pentane at a series of fixed temperatures to produce an equilibrium mixture of various fixed total pressures to form a quasi-binary system containing compounds such as COP, C2H,, C3H,, H2S, ~ I - C ~ H , ~ , and n-C,H,,. The experimental results provide data useable to adjust parameters and test for "proof of correlations". I t suggests when the relative volatility ratios of the key components become unfavorable for LPG recovery and when the overhead vaporization losses become excessive and the fate of small concentrations of H2S, feasible column pressures, and overhead column tem- peratures. I t shows the importance of verifying the V-L -E behavior at near-specification concentrations when breaking an azeotrope or near-azeotropic pinch, employing the principles of extractive distillation.

In an earlier paper (Hong and Kobayashi, 1985), ex- tensive phase-equilibria data were reported for two qua- si-binary mixtures a t feasible operating conditions to separate COz from CzHB using n-C,HI2 as the extractive agent. The first quasi-binary mixtures were formed by mixing a near-azeotropic mixture of COz and CzH6 with n-pentane at several fixed temperatures to a series of total pressures. The second quasi-binary mixture was formed by mixing a near-specification C02-rich gas mixture con- taining a small amount of C2H6 with n-C5HI2 to form a mixture of various total pressures.

Other V-L-E studies have been conducted on either (a) the associated binary systems as reviewed by Hiza et al. (1975,1982) or (b) multicomponent hydrocarbon systems containing small-to-moderate concentrations of carbon dioxide (Yarborough, 1972).

In this study, two additional near-specification C02-rich gas mixtures are added to (1) n-pentane and then to (2) toluene.

These studies focus on the development of an extractive distillation process for the production of a C02-rich gas to be recycled to the EOR field and raw LPG mixtures containing the H2S.

Table I. Composition of Five-Component COz-Rich Gas Mixtures

gas comp gas comp comDonent mol fraction" comDonent mol fraction"

COZ 0.945 870 c3 0.024 570 c2 0.017 49 n-C., 0.006 054 H*S 0.006016 total 1.000 000

Normalized compositions.

The severe H2S specification in the C02-recycle stream points to the desirability of evaluating an aromatic ex- tractive agent. Toluene was chosen as the aromatic solvent because of its abundance and low freezing point. Prelim- inary indications that toluene might be an effective solvent were revealed in an earlier study by Mundis et al. (1977).

Exper imenta l Detai ls The experimental apparatus used in this study was a

vapor-recycle vapor-liquid equilibrium apparatus de- scribed by Elliot et al. (1974) and Mraw et al. (1978). Significant improvements have been made in the sample homogenizer and analytical system, which has led to more

0196-4305/86/1125-0584$01.50/0 0 1986 American Chemical Society

Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986 585

10

W 3 _J

a ' 3 x

300 IO00 " R E S S U R E , PSIA

Figure 1. K value vs. pressure plot for COz and C2H, in a five- component mixtureln-pentane quasi-binary system.

rapid data acquisition and better data reproducibility. A modification was carried out on the gas chromatographic unit by adding a separate valve oven. A separate tem- perature control to maintain the valve oven at a temper- ature higher than that of the analytical column oven was constructed, thus preventing the heavier components of the mixture from condensing before entering the analytical

i 100 300 1000

PRESSURE, PSIA

Figure 2. PK vs. pressure plot for COz and CzHB in a five-compo- nent mixtureln-pentane quasi-binary system.

column which, on occasions, had an initial temperature as low as 50 "C.

It was necessary to conduct a chromatographic calibra- tion for each of the components in the mixture. The calibration curves were established by employing the method reported by Mraw et al. (1978) and Hong and Kobayashi (1981). The calibration curves all showed linear behavior.

In this way, the concentrations of a given sample was

Table 11. Original Vapor-Liquid Equilibrium Composition of a Quasi-Binary Mixture Containing COz, CzH6, H2S, C3Ha, and n -C,H,, with n -C,H,,

~~

pressure, liquid mol fractions vapor mol fractions psia kPa COP CzH6 H2S C3Hs n-CIH,o n-C&I,z COP C2HB HzS C& n-C,H,o n-CSH,z

T = -20.029 "C, -4.052 "F 100 689 0.169 7 0.005 145 0.001 707 0.009 564 0.002 519 0.8114 0.9674 0.010 38 0.002 873 0.003 989 0.000 220 6 0.015 09 150 1034 0.293 7 0.008 047 0.002 730 0.014 98 0.003 958 0.6766 0.9715 0.011 07 0.003 024 0.004 241 0.000 242 5 0.009 927 200 1379 0.453 5 0.010 69 0.003 760 0.019 46 0.005078 0.5076 0.9720 0.012 36 0.003 114 0.004 869 0.000 285 9 0.007 387 248 1710 0.760 2 0.014 18 0.005 224 0.022 96 0.005606 0.1820 0.9655 0.018 29 0.003 586 0.007 367 0.000 501 7 0.004 778

T = -10.007 "C, 13.987 O F

100 689 0.140 7 0.004 433 0.001 370 0.008 397 0.002 282 0.8428 0.9566 0.010 49 0.003 049 0.004 656 0.000 306 8 0.024 94 150 1034 0.222 7 0.006 590 0.002 096 0.012 70 0.003 368 0.7526 0.9629 0.011 20 0.003 151 0.005093 0.000 313 3 0.017 31 200 1379 0.327 7 0.008914 0.002 973 0.017 03 0.004 503 0.6388 0.9658 0.011 80 0.003 255 0.005 490 0.000 345 9 0.012 93 250 1724 0.459 8 0.011 02 0.003 830 0.02040 0.005 421 0.4995 0.9673 0.012 73 0.003 381 0.005 879 0.000412 6 0.01032 300 2068 0.643 6 0.013 10 0.004 745 0.022 84 0.005 883 0.3099 0.9661 0.014 97 0.003 524 0.007 020 0.0004789 0.007 903 334 2303 0.798 8 0.014 79 0.005 345 0.023 56 0.005 775 0.1517 0.9619 0.018 89 0.002 840 0.008 746 0.000 710 7 0.005 884

T = 0.028 "C, 32.050 O F

100 689 0.114 7 0.003 964 0.001 280 0.008 270 0.002 277 0.8695 0.9387 0.011 58 0.003 568 0.006 047 0.000412 9 0.039 65 150 1034 0.184 6 0.006 788 0.002 090 0.01841 0.006 190 0.7820 0.9463 0.013 40 0.003 778 0.009 130 0.000 784 1 0.026 66 200 1379 0.254 9 0.007 591 0.002 618 0.015 32 0.004 122 0.7154 0.9566 0.011 99 0.003 534 0.006 176 0.000422 6 0.020 79 300 2068 0.437 3 0.012 19 0.004 390 0.030 1 2 0.009 390 0.5070 0.9564 0.01444 0.004 162 0.009 838 0.000861 8 0.014 43 400 2758 0.701 5 0.014 29 0.005 657 0.029 31 0.008661 0.2406 0.9579 0.016 42 0.004 251 0.01070 0.001 015 0.009 930 446 3075 0.835 2 0.015 44 0.005649 0.024 50 0.006 200 0.1130 0.9578 0.019 43 0.004 175 0.010 68 0.0009806 0.006 920

T = +10.017 "C, 50.031 O F 100 689 0.095 14 0.003 203 0.000972 0.006 552 0.001 833 0.8918 0.9160 0.011 17 0.003 157 0.006 125 0.000476 6 0.062 43 150 1034 0.1498 0.005073 0.001 502 0.01099 0.003 120 0.8295 0.9342 0.012 19 0.003 210 0.007 296 0.000577 0.042 53 200 1379 0.2080 0.006803 0.002 117 0.015 03 0.004 363 0.7636 0.9422 0.012 76 0.003 653 0.007 647 0.000 627 4 0.033 09 300 2068 0.337 3 0.009 765 0.003 306 0.021 60 0.006 318 0.6217 0.9503 0.013 39 0.003 874 0.008456 0.000 731 3 0.023 25 400 2758 0.502 9 0.012 43 0.004 559 0.026 37 0.007 553 0.4462 0.9533 0.014 27 0.004060 0.009 418 0.000879 6 0.018 14 500 3447 0.701 8 0.014 30 0.005 409 0.027 02 0.007 554 0.2439 0.9546 0.01602 0.004 230 0.01043 0.001 089 0.013 57 557 3840 0.8160 0.015 21 0.005 570 0.025 54 0.006 816 0.1308 0.9542 0.018 24 0.004 369 0.011 67 0.001 286 0.010 20

100 150 200 300 400 497 600 659

689 1034 1379 2068 2758 3427 4137 4544

0.079 74 0.1284 0.1785 0.282 0 0.409 4 0.549 8 0.704 6 0.804 5

0.002 860 0.004 505 0.006 096 0.008811 0.011 28 0.013 23 0.014 33 0.015 33

0.000 791 4 0.001 376 0.002 018 0.003 100 0.003 899 0.004 904 0.005 492 0.005 664

0.006 234 0.010 41 0.014 28 0.020 73 0.025 42 0.028 00 0.027 83 0.026 57

T = +20.001 "C, 68.002 O F 0.001 838 0.9085 0.8846 0.003 130 0.8521 0.9137 0.004 323 0.7948 0.9256 0.006 369 0.6790 0.9377 0.007 651 0.5424 0.9442 0.008 299 0.3957 0.9519 0.007 975 0.2398 0.9485 0.007 237 0.1407 0.9497

0.011 91 0.012 64 0.013 10 0.013 72 0.014 08 0.014 90 0.015 96 0.017 31

0.003 019 0.003 546 0.003 962 0.004 172 0.004 192 0.004 360 0.004 363 0.004 502

0.007 758 0.008 479 0.009 315 0.010 07 0.010 27 0.01097 0.012 05 0.012 80

0.000665 1 0.000 799 7 0.000 856 6 0.000 998 3 0.001 025 0.001 192 0.001 416 0.001 562

0.092 00 0.060 80 0.047 13 0.033 33 0.026 19 0.022 14 0.017 69 0.014 75

586 Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986

~

4.0&

I I I I I l l I00 300 600

PRESSURE, PSlA

Figure 3. K value vs. pressure plot for H2S in a five-component mixtureln-pentane quasi-binary system.

determined to be between 0.02 and 0.3% commensurate with the nature of the component, e.g., 0.02% for n-pen- tane and 0.3% for C02 and ethane.

0.d. column packed with 80/100-mesh Porapak Q was utilized to effect the separation. A thermal conductivity detector was used. The signal from the de- tector was integrated and reported automatically.

Materials. n-Pentane, research grade, 99.96 mol %

A 6 f t long

I' '

I I I l l l l l

I

Y 600k

~ l : f l ~ I I l

100 IO0 300 600

PRESSURE, PSlA

Figure 4. PK vs. pressure plot for H2S in a five-component mix- tureln-pentane quasi-binary system.

pure, was provided by Phillips Petroleum Co. No de- tectable impurities were found by gas chromatographic (GC) analysis.

"Baker Analyzed Reagent Grade" toluene was purchased from J. T. Baker, with stated purity of 99%. No impurities were detected by GC analysis.

A five-component gas mixture added to n-pentane or to toluene was synthesized in this laboratory. Instrument

Table 111. K Values and Relative Volatilities of Various "Key ComDonents"

100 150 200 248

100 150 200 250 300 334

100 150 200 300 400 446

100 150 200 300 400 500 557

100 150 200 300 400 497 600 659

689 1034 1379 1710

689 1034 1379 1724 2068 2303

689 1034 1379 2068 2758 3075

689 1034 1379 2068 2758 3447 3840

689 1034 1379 2068 2758 3427 4137 4544

5.7007 3.3078 2.1433 1.2701

6.7986 4.3238 2.9473 2.1037 1.5011 1.2042

8.1840 5.1262 3.7528 2.1873 1.3655 1.1468

9.6279 6.2363 4.5298 2.8173 1.8956 1.3602 1.1694

11.0899 7.1163 5.1854 3.3252 2.3063 1.7313 1.3462 1.1805

2.0175 1.3751 1.1564 1.2898

2.3663 1.7000 1.3238 1.1550 1.1431 1.2776

2.9213 1.9741 1.5799 1.1842 1.1490 1.2588

3.4877 2.4029 1.8756 1.3712 1.1478 1.1204 1.1992

4.1628 2.8055 2.1489 1.5571 1.2482 1.1262 1.1140 1.1294

1.6831 1.1076 0.8282 0.6864

2.2255 1.5033 1.0949 0.8829 0.7426 0.7183

2.7875 1.8077 1.3497 0.9480 0.7515 0.7391

3.2477 2.1372 1.7256 1.1718 0.8905 0.7820 0.7844

3.8135 2.5766 1.9632 1.3458 1.0751 0.8891 0.7944 0.7948

T = -20.029 "C, -4.052 "F 0.4171 0.087 57 0.01860 0.2831 0.061 28 0.01467 0.2502 0.056 31 0.014 55 0.3209 0.089 49 0.026 25

T = -10.007 "C, 13.987 O F 0.5545 0.134 4 0.029 59 0.4011 0.093 03 0.023 00 0.3224 0.076 81 0.020 24 0.2882 0.076 11 0.02066 0.3074 0.081 41 0.025 50 0.3712 0.1231 0.03879

T = 0.028 "C, 32.050 "F 0.7312 0.181 3 0.04560 0.4959 0.1267 0.03409 0.4031 0.102 5 0.02907 0.3266 0.091 78 0.02845 0.3650 0.117 2 0.041 27 0.4359 0.158 2 0.061 24

T = +10.017 "C, 50.031 "F 0.9348 0.2600 0.07000 0.6639 0.1849 0.051 27 0.5088 0.143 8 0.043 33 0.3915 0.115 7 0.037 40 0.3572 0.116 5 0.040 65 0.3859 0.144 1 0.05605 0.4569 0.1887 0.07801

T = +20.001 "C, 68.002 "F 1.2443 0.361 7 0.101 2 0.8145 0.255 5 0.071 36 0.6523 0.198 0 0.059 29 0.4858 0.156 7 0.049 09 0.4040 0.1340 0.04829 0.3918 0.143 6 0.055 95 0.4330 0.177 5 0.073 77 0.4816 0.2158 0.1048

2.83 2.41 1.85 0.98

2.87 2.54 2.23 1.82 1.31 0.94

2.80 2.60 2.38 1.85 1.19 0.91

2.76 2.60 2.42 2.05 1.65 1.21 0.98

2.66 2.54 2.41 2.14 1.85 1.54 1.21 1.05

3.39 2.99 2.59 1.85

3.05 2.88 2.69 2.38 2.02 1.68

2.94 2.84 2.78 2.31 1.82 1.55

2.96 2.92 2.63 2.40 2.13 1.74 1.49

2.91 2.76 2.64 2.47 2.15 1.95 1.69 1.49

1.198 1.242 1.396 1.879

1.063 1.131 1.209 1.308 1.539 1.779

1.048 1.092 1.172 1.249 1.529 1.705

1.074 1.124 1.087 1.170 1.289 1.433 1.529

1.092 1.089 1.095 1.157 1.161 1.267 1.402 1.421

13.667 11.684 8.566 3.958

12.260 10.779 9.141 7.299 4.883 3.244

11.192 10.337 9.309 6.697 3.741 2.631

10.298 9.393 8.902 7.196 5.307 3.525 2.559

8.913 8.737 7.948 6.844 5.708 4.418 3.109 2.451

Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986 587

Table IV. Original Vapor-Liquid Equilibrium Composition of a Mixture Containing CO,, CzH6, H2S, C3Ha, and n-C4H,, with Toluene pressure liquid mol fractions vapor mol fractions

Dsia kPa CO, C,H, H,S C,Ha n-CaHln toluene CO, C,H, H,S C,H, n-CaHln toluene T = -20.029 "C, -4.052 O F

100 689 0.1688 0.004 255 0.001 405 0.008655 0.002 388 0.8161" 0.9767 0.014 70 0.001 171 0.006 469 0.000 367 4 0.000406 4a 150 1034 0.295 9 0.006 556 0.002 481 0.013 70 0.003 810 0.6872" 0.9751 0.015 56 0.001 411 0.006 868 0.000 399 9 0.000 303 9" 200 1379 0.456 8 0.009 220 0.003 535 0.01875 0.005035 0.5435" 0.9730 0.016 81 0.001 623 0.007 442 0.000449 5 0.000 297 4O 250 1724 0.766 7 0.013 74 0.004 521 0.022 38 0.005 490 0.2481" 0.9644 0.022 84 0.002 449 0.009 273 0.000 607 6 0.000 257 lo

100 689 0.144 2 0.003 843 0.001 517 0.008699 0.002 704 0.8391 0.9742 0.01505 0.001 434 0.008 312 0.000 564 1 0.000836 3 150 1034 0.223 7 0.005 361 0.002 328 0.012 58 0.004082 0.7523 0.9734 0.015 52 0.001 489 0.008402 0.000628 7 0.000 591 4 200 1379 0.314 7 0.007 151 0.003 387 0.017 72 0.005 140 0.6526 0.9722 0.01606 0.001 735 0.008937 0.000647 5 0.000 5240 250 1724 0.4259 0.009020 0.003790 0.02047 0.006088 0.5345 0.9711 0.01665 0.001 912 0.009 160 0.0006890 0.0005308 315 2172 0.675 5 0.012 45 0.004 310 0.023 73 0.006459 0.2775 0.9675 0.019 26 0.002 318 0.009 649 0.000806 1 0.000487 5

T = 0.028 "C, 32.050 O F

T = -10.007 "C, 13.987 O F

100 689 0.127 3 0.003 274 0.000 901 7 0.007 275 0.002 070 0.8593 0.9733 0.01504 0.001 076 0.008 374 0.000584 4 0.001 629 150 1034 0.177 1 0.004 590 0.001 445 0.01063 0.003 121 0.8032 0.9720 0.015 59 0.001 275 0.009 365 0.000662 7 0.001 141 200 1379 0.2507 0.006064 0.001 915 0.014 59 0.004 309 0.7223 0.9716 0.015 74 0.001 245 0.009 601 0.000 737 5 0.001 121 300 2068 0.396 7 0.008 727 0.002 822 0.02044 0.006 213 0.5650 0.9702 0.016 39 0.001 330 0.010 30 0.000 843 5 0.001 109 350 2413 0.505 0 0.01040 0.003 840 0.023 07 0.006693 0.4509 0.9690 0.017 02 0.001 589 0.010 50 0.000 814 2 0.001 064 406 2799 0.676 4 0.012 50 0.004043 0.024 56 0.006 818 0.2757 0.9666 0.018 31 0.001 917 0.010 89 0.000 921 8 0.001 004

T = +10.017 "C, 50.031 O F

100 689 0.111 7 0.002 977 0.001 065 0.006 962 0.002 141 0.8751 0.9703 0.015 08 0.001 640 0.009 527 0.000 765 2 0.002 667 150 1034 0.161 2 0.004 199 0.001 622 0.010 26 0.003 228 0.8197 0.9696 0.015 53 0.001 785 0.010 29 0.000 870 7 0.002 011 200 1379 0.208 3 0.005 357 0.002 471 0.01499 0.005072 0.7637 0.9668 0.016 03 0.002 118 0.012 16 0.001 113 0.001 764 300 2068 0.3200 0.007 702 0.003 961 0.021 83 0.005 815 0.6400 0.9654 0.016 45 0.002 395 0.013 01 0.001 009 0.001 617 400 2758 0.470 5 0.010 12 0.004 286 0.023 70 0.007 205 0.4842 0.9671 0.016 56 0.002 128 0.011 57 0.001 074 0.001 583 500 3447 0.6857 0.012 96 0.004881 0.026 33 0.007 619 0.2625 0.9651 0.017 83 0.002 203 0.011 91 0.001 135 0.001 460 550 3792 0.816 2 0.014 37 0.005 296 0.027 72 0.007 546 0.1289 0.9620 0.019 42 0.002 799 0.013 47 0.001 459 0.001 083

T = +20.001 "C, 68.002 O F

100 689 0.093 11 0.002 570 0.000696 9 0.005 906 0.001 812 0.9014 0.9675 0.015 28 0.001 299 0.010 32 0.0009040 0.004 671 150 1034 0.132 0 0.003 554 0.001 273 0.008 496 0.002 611 0.8523 0.9677 0.015 54 0.001 657 0.010 91 0.000961 1 0.003 485 200 1379 0.1786 0.004 630 0.001 895 0.011 53 0.003 694 0.7997 0.9671 0.015 69 0.001 901 0.011 34 0.000991 3 0.002 948 300 2068 0.273 6 0.006 769 0.003 016 0.016 82 0.005 507 0.6943 0.9665 0.015 93 0.002 223 0.011 87 0.001 171 0.002 293 400 2758 0.3700 0.008 524 0.003 831 0.020 99 0.006 744 0.5898 0.9656 0.016 18 0.002 361 0.012 41 0.001 211 0.002 165 500 3447 0.515 5 0.010 56 0.004 672 0.025 58 0.007 957 0.4353 0.9645 0.016 68 0.002 566 0.012 74 0.001 342 0.002 151 552 3806 0.5908 0.011 95 0.005 127 0.026 27 0.007 928 0.3579 0.9640 0.017 08 0.002 793 0.012 75 0.001 348 0.002 186 604 4164 0.689 0 0.013 10 0.005 366 0.026 72 0.007 739 0.2580 0.9630 0.017 70 0.002 916 0.012 98 0.001 401 0.002 011 647 4461 0.792 5 0.01441 0.005 251 0.026 99 0.007 578 0.1532 0.9615 0.018 55 0.003 154 0.013 29 0.001 468 0.002 024

a Recommended values (from COP-toluene binary system).

grade COP with purity of 99.99 mol % purchased from Airco, research grade ethane, propane, and n-butane pro- vided by Phillips Petroleum Co. with minimum purity of 99.96 mol % , and C.P. grade HPS purchased from Math- eson Gas Products, with a stated purity of 99.5% , were used in synthesizing the gas mixture. HPS was further purified by freeze-thaw cycles to remove free hydrogen. All components were examined by GC prior to mixing. The normalized composition is tabulated on Table I.

Experimental Results and Discussion

The experimental results are presented for two quasi- binary systems at feasible distillation conditions in Tables 11-VI and Figures 1-7. The data, particularly, presents V-L-E in the near-specification COP-rich concentration region over a substantial range of pressures and temper- atures.

A t low temperature (-20 "C), the vapor composition of toluene was so low that it was on the verge of the detector's detection limit and the peak areas registered were often inconsistent; hence, the vapor composition of toluene from the COP-toluene binary system was recommended, as shown in Tables IV and V and Figure 7.

The results indicate the conditions which extractive separation of COz and LPG constituents are feasible. They also indicate that the K values of COP and ethane approach one another and cross as the pressure increases, and the relative volatility of C02 and ethane inverts when excessive pressures are reached (Figures 1 and 2). High pressures also cause an excessive amount of n-pentane losses in the overhead. The high COP concentrations in the liquid phase help to suppress the relative volatility of HPS with respect to CO,, causing the total pressure - K-value products to be almost pressure-independent over a wide range of pressures, as shown on Figure 4.

Solvent loss is an important design factor; the results (Table 11) show that the mole fraction of n-pentane in the vapor phase is high and hence the solvent losses are rela- tively large. The upper pressure range of operation is limited by the high solubility of COP in the n-pentane-rich liquid phase and the n-pentane vaporization losses.

To study the effect of solvent structure, toluene was substituted for n-pentane as a second solvent. The V-L-E data (Table IV) indicate that the solvent losses are much lower for toluene than when n-pentane is used as a solvent. Ethane recovery will be reduced when toluene is the ex- tractive solvent a t the same liquid rate and that HPS

588

Table V. K Values and Relative Volatilities of Various 'Key Components" of a Mixture Containing C02, C2Hs, HzS, C3HS, and n -C4Hlo with Toluene

Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986

pressure K values

psis kPa c02 CZH6 HZS CSHE n-C4H10 toluene IYC02/C2Hg %02/H*S % ~ H ~ / H z S %Op/CaHg

T = -20.029 O C , -4.052 O F

100 689 150 1034 200 1379 250 1724

100 689 150 1034 200 1379 250 1724 315 2172

100 689 150 1034 200 1379 300 2068 350 2413 406 2799

100 689 150 1034 200 1379 300 2068 400 2758 500 3447 550 3792

100 689 150 1034 200 1379 300 2068 400 2758 500 3447 552 3806 604 4164 647 4461

5.7861 3.4548 0.7300" 3.2954 2.3734 0.5000" 2.1300 1.8232 0.4000" 1.2579 1.6623 0.4500"

6.7559 3.9162 0.9453 4.3514 2.8950 0.6396 3.0848 2.2458 0.5123 2.2801 1.8459 0.5045 1.4323 1.5470 0.5378

7.6457 4.5938 1.1933 5.4884 3.3965 0.8824 3.8755 2.5956 0.6501 2.4457 1.8781 0.4713 1.9188 1.6365 0.4138 1.4290 1.4648 0.4742

8.6867 5.0655 1.5399 6.0149 3.6985 1.1005 4.6414 2.9923 0.8571 3.0169 2.1358 0.6046 2.0555 1.6364 0.4965 1.4075 1.3758 0.4513 1.1786 1.3514 0.5285

10.3909 7.3311 5.4149 3.5325 2.6097 1.8710 1.6317 1.3977 1.2132

5.9455 4.3725 3.3888 2.3534 1.8982 1.5795 1.4293 1.3511 1.2873

1.8640 1.3016 1.0032 0.7371 0.6163 0.5492 0.5448 0.5434 0.6006

0.7474 0.153 9 0.000497 gb 0.5013 0.1050 0.000442 2* 0.3969 0.089 28 0.000 547 I* 0.4143 0.1107 0.001 036b

T = -10.007 OC, 13.987 OF 0.9555 0.208 6 0.000 996 6 0.6679 0.154 0 0.000 786 1 0.5043 0.126 0 0.OOO 802 9 0.4475 0.113 2 0.0009930 0.4066 0.1248 0.001 757

T = +0.028 OC, 32.050 O F

1.1511 0.282 3 0.001 896 0.8810 0.212 3 0.001 421 0.6581 0.171 2 0.001 552 0.5039 0.135 8 0.001 963 0.4551 0.121 6 0.002 360 0.4434 0.135 2 0.003 642

T = +10.017 "C, 50.031 O F

1.3684 0.357 4 0.003 048 1.0029 0.269 7 0.002 453 0.8112 0.2194 0.002310 0.5960 0.173 5 0.002 527 0.4882 0.149 1 0.003 269 0.4523 0.149 0 0.005 562 0.4859 0.193 3 0.008 402

T = +20.001 OC, 68.002 OF 1.7474 0.498 9 0.005 182 1.2841 0.368 1 0.004089 0.9835 0.275 8 0.003 687 0.7057 0.212 6 0.003 303 0.5912 0.1796 0.003671 0.4980 0.168 7 0.004 941 0.4853 0.1700 0.006 108 0.4858 0.181 0 0.007 795 0.4924 0.193 7 0.013 21

1.67 1.39 1.17 0.76

1.73 1.50 1.37 1.24 0.93

1.66 1.62 1.49 1.30 1.17 0.97

1.71 1.63 1.55 1.41 1.26 1.02 0.87

1.75 1.68 1.60 1.50 1.37 1.18 1.14 1.03 0.94

7.93' 6.59' 5.33c 2.8OC

7.15 6.80 6.02 4.52 2.66

6.41 6.22 5.96 5.19 4.64 3.013

5.64 5.47 5.42 4.99 4.14 3.12 2.23

5.57 5.63 5.40 4.80 4.23 3.41 3.00 2.57 2.02

4.73' 4.75' 4.56' 3.6gC

4.14 4.53 4.38 3.66 2.88

3.85 3.85 3.99 3.98 3.95 3.09

3.29 3.36 3.49 3.53 3.30 3.05 2.56

3.19 3.36 3.38 3.19 3.08 2.88 2.62 2.49 2.14

7.74 6.57 5.37 3.04

7.07 6.52 6.12 5.10 3.52

6.64 6.23 5.89 4.85 4.22 3.22

6.35 6.00 5.72 5.06 4.21 3.11 2.43

5.95 5.71 5.51 5.01 4.41 3.76 3.36 2.88 2.46

"Extrapolated values from K vs. 1/T plot. Recommended values (from COP-toluene binary system). Results from extrapolated values.

Table VI. K Values and Original Vapor-Liquid Equilibrium Compositions of C02 and Toluene at -10 and -20 "C

pressure liquid mol fractions vapor mol fractions K values ~~

COP toluene psia kPa coz toluene COZ toluene 5" = -10.007 "C, 13.987 O F

100 150 200 250 299 322

100 150 200 250

689 1034 1379 1724 2062 2220

689 1034 1379 1710

0.1494 0.2373 0.3201 0.4425 0.6133 0.7456

0.1839 0.3128 0.4565 0.7519

0.8506 0.999 19 0.7627 0.999 38 0.6799 0.999 41 0.5575 0.999 49 0.3867 0.999 44 0.2544 0.999 43

T = -20.029 "C, -4.052 OF 0.8161 0.999 59 0.6872 0.999 73 0.5435 0.999 67 0.2481 0.999 74

0.000 807 2 0.OOO 573 3 0.OOO 566 3 0.000 550 2 0.OOO 551 6 0.000 568 8

O.OO0 406 4 0.OOO 303 9 0.OOO 297 4 0.000 257 1

6.6880 4.2115 3.1222 2.2587 1.6296 1.3404

5.4355 3.1961 2.1899 1.3296

0.000 948 9 0.000751 6 0.000 832 9 0.000 986 9 0.001 426 0.002 236

0.000 497 9 0.000 442 2 0.000 547 1 0.001 036

specification in the overhead can be more easily reached at a much lower solvent flow rate. The propane and heavier LPG recovery is slightly lower than when using purely alkane solvent but should still be satisfactory.

Since the solvent structure will significantly affect the

process performance, it should be monitored carefully during plant operations.

In conclusion, the data should be sufficiently accurate for either "the development of correlations" or to demon- strate the 'proof of correlation".

Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986 589

i

I

h 0, I I 1 1 1 l - 5 -

3C 22G 300 40C 600 800 ZFiESSdRE, PSiA

Figure 5. K value vs. pressure plot for C3H8, n-C4Hlo, and n-C5HI2 in a five-component mixtureln-pentane quasi-binary system.

c 4 -20cc 0 20°C - e - 0°C 0 I [ _ _ .:.;.. ;;:;;oL.-Ec I

0 I cot, , 1 3. c0 50 zoo 300 4cc " 7 ~

PRESSURE, "SIA

Figure 6. K value vs. pressure plot for COz, C 2 H e , and H 2 S in a five-component mixture/toluene quasi-binary system.

Acknowledgment

We acknowledge the sponsors of the work, The Gas Processors Association, and the following industrial sponsors for the support of this work: C. E. Randall, Cities Service, DMI, McDermott, Exxon, Koch Process Systems, and Shell Development Co. Phillips Petroleum Co. pro-

L i

0 20°C b 0 10°C

i 3 -

- -d

C.3CC21 I 1 I 1 i 1 1

PQESSURE , PSlA

Figure 7. K value vs. pressure plot for C3H8, n-C4HIo, and toluene in a five-component mixture/toluene quasi-binary system.

'00 i50 200 300 420 5CC i C 0

vided research grade ethane, propane, n-butane, and n- pentane.

Registry No. COP, 124-38-9; C2Hs, 74-84-0; C3HB, 74-98-6; n-C4Hlo, 106-97-8; n-C5H12, 109-66-0; H2S, 7783-06-4.

Literature Cited Elliot, D. G.: Chen. R. J. J.; Chappelear, P. S. J. Chem. Eng. Data 1974, 79

(I), 71. Hiza, M. J.; Kidnay, A. J.; Miiier, R. C. "Equilibrium Properties of Fluid Mix-

tures-I, A Bibliography of Experimental Data on Selected Fluids"; Plenum Press: New York-Washington-London, 1975; pp 59-60.

Hiza, M. J.; Kidnay, A. J.; Miller, R. C. "Equilibrium Properties of Fluid Mix- tures-2, A Bibliography of Experimental Data on Selected Fluids": Plenum Press: New York-Washington-London, 1982; pp 89-91,

Hong, J. H.; Kobayashi, R. J. Chem. Eng. Data 1981, 26(2), 127. Hong, J. H.; Kobayashi. R. Ind. Eng. Chem. Process Des. Dev., in press. Mraw, S. C. ; Hwang, S. C.; Kobayashi, R. J. Chem. Eng. Data 1978, 23(2),

Mundis, C. J.; Yarborough, L.; Robinson, R. L., Jr. Ind. Eng. Chem. Process

Yarborough. L. J. Chem. Eng. Data 1972, 17(2) , 129.

135.

Des. Dev. 1977, 16 (2), 254.

Received for review June 27, 1985 Revised manuscript received August 9, 1985

Accepted October 21, 1985