584
Ind. Eng.
Chem. Process Des. Dev. 1986, 2 5 , 584-589
Provder, T., Ed. "Size Exclusion Chromatography. Methodology and Characterization of Polymers and Related Materlals"; Amerlcan Chemlcal Soclety: 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"; Lapldus, 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: Washington, 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 , 1785. 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.
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 temperatures. 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), extensive phase-equilibria data were reported for two quasi-binary mixtures a t feasible operating conditions to separate COz from CzHBusing n-C,HI2 as the extractive agent. The first quasi-binary mixtures were formed by mixing a near-azeotropic mixture of COz and CzH6with 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-richgas mixture containing a small amount of C2H6with n-C5HI2to 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-ComponentCOz-Rich Gas
Mixtures
comDonent
COZ
gas comp mol fraction"
comDonent
c2
0.945870 0.017 49
c3
H*S
0.006016
total
n-C.,
gas comp mol fraction" 0.024 570 0.006054 1.000000
Normalized compositions.
The severe H2Sspecification in the C02-recyclestream points to the desirability of evaluating an aromatic extractive agent. Toluene was chosen as the aromatic solvent because of its abundance and low freezing point. Preliminary indications that toluene might be an effective solvent were revealed in an earlier study by Mundis et al. (1977). E x p e r i m e n t a l Details
The experimental apparatus used in this study was a vapor-recycle vapor-liquid equilibrium apparatus described 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$01.50/00 1986 American Chemical Society
Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986 585 10
W 3 _J
a ' 3 x
100
IO00
300 "RESSURE, PSIA
300 PRESSURE, PSIA
i
1000
Figure 2. PK vs. pressure plot for COz and CzHBin a five-component mixtureln-pentane quasi-binary system.
Figure 1. K value vs. pressure plot for COz and C2H, in a fivecomponent 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 temperature control to maintain the valve oven a t a temperature higher than that of the analytical column oven was constructed, thus preventing the heavier components of the mixture from condensing before entering the analytical
column which, on occasions, had an initial temperature as low as 50 "C. It was necessary to conduct a chromatographic calibration 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, psia kPa
COP
CzH6
liquid mol fractions H2S C3Hs
n-CIH,o
n-C&I,z
COP
C2HB
vapor mol fractions HzS C& n-C,H,o
n-CSH,z
T = -20.029 "C, -4.052 "F 0.010 38 0.011 07 0.012 36 0.018 29
0.002 873 0.003 024 0.003 114 0.003 586
0.003 989 0.004 241 0.004 869 0.007 367
0.000 220 6 0.000 242 5 0.000 285 9 0.000 501 7
0.015 09 0.009 927 0.007 387 0.004 778
0.9566 0.9629 0.9658 0.9673 0.9661 0.9619
0.010 49 0.011 20 0.011 80 0.012 73 0.014 97 0.018 89
0.003 049 0.003 151 0.003 255 0.003 381 0.003 524 0.002 840
0.004 656 0.005093 0.005 490 0.005 879 0.007 020 0.008 746
0.000 306 8 0.000 313 3 0.000 345 9 0.000412 6 0.0004789 0.000 710 7
0.024 94 0.017 31 0.012 93 0.01032 0.007 903 0.005 884
"C, 32.050 O F 0.8695 0.9387 0.7820 0.9463 0.7154 0.9566 0.5070 0.9564 0.2406 0.9579 0.1130 0.9578
0.011 58 0.013 40 0.011 99 0.01444 0.016 42 0.019 43
0.003 568 0.003 778 0.003 534 0.004 162 0.004 251 0.004 175
0.006 047 0.009 130 0.006 176 0.009 838 0.01070 0.010 68
0.000412 9 0.000 784 1 0.000422 6 0.000861 8 0.001 015 0.0009806
0.039 65 0.026 66 0.020 79 0.014 43 0.009 930 0.006 920
0.9160 0.9342 0.9422 0.9503 0.9533 0.9546 0.9542
0.011 17 0.012 19 0.012 76 0.013 39 0.014 27 0.01602 0.018 24
0.003 157 0.003 210 0.003 653 0.003 874 0.004060 0.004 230 0.004 369
0.006 125 0.007 296 0.007 647 0.008456 0.009 418 0.01043 0.011 67
0.000476 6 0.000577 0.000 627 4 0.000 731 3 0.000879 6 0.001 089 0.001 286
0.062 43 0.042 53 0.033 09 0.023 25 0.018 14 0.013 57 0.010 20
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
100 689 0.169 7 150 1034 0.293 7 200 1379 0.453 5 248 1710 0.760 2
0.005 145 0.008 047 0.010 69 0.014 18
0.001 707 0.002 730 0.003 760 0.005 224
0.009 564 0.014 98 0.019 46 0.022 96
0.002 519 0.003 958 0.005078 0.005606
0.8114 0.6766 0.5076 0.1820
100 150 200 250 300 334
689 1034 1379 1724 2068 2303
0.140 7 0.222 7 0.327 7 0.459 8 0.643 6 0.798 8
0.004 433 0.006 590 0.008914 0.011 02 0.013 10 0.014 79
0.001 370 0.002 096 0.002 973 0.003 830 0.004 745 0.005 345
0.008 397 0.012 70 0.017 03 0.02040 0.022 84 0.023 56
0.002 282 0.003 368 0.004 503 0.005 421 0.005 883 0.005 775
0.8428 0.7526 0.6388 0.4995 0.3099 0.1517
100 150 200 300 400 446
689 1034 1379 2068 2758 3075
0.114 7 0.184 6 0.254 9 0.437 3 0.701 5 0.835 2
0.003 964 0.006 788 0.007 591 0.012 19 0.014 29 0.015 44
0.001 280 0.002 090 0.002 618 0.004 390 0.005 657 0.005649
0.008 270 0.01841 0.015 32 0.030 1 2 0.029 31 0.024 50
T = 0.028 0.002 277 0.006 190 0.004 122 0.009 390 0.008661 0.006 200
100 150 200 300 400 500 557
689 1034 1379 2068 2758 3447 3840
0.095 14 0.1498 0.2080 0.337 3 0.502 9 0.701 8 0.8160
0.003 203 0.005073 0.006803 0.009 765 0.012 43 0.014 30 0.015 21
0.000972 0.001 502 0.002 117 0.003 306 0.004 559 0.005 409 0.005 570
0.006 552 0.01099 0.015 03 0.021 60 0.026 37 0.027 02 0.025 54
0.001 833 0.003 120 0.004 363 0.006 318 0.007 553 0.007 554 0.006 816
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
0.9674 0.9715 0.9720 0.9655
T = -10.007 "C, 13.987 O F
T = +10.017 "C, 50.031 O F 0.8918 0.8295 0.7636 0.6217 0.4462 0.2439 0.1308
586
Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986
I'
~
4.0&
Y
I
I
I
I
I
300 PRESSURE, PSlA
l
l
l
l
l
l
l
I
600k
100
600
I
'
~
I00
I
I
l
IO0
:
I f I
300 PRESSURE, PSlA
l
l
~
600
Figure 3. K value vs. pressure plot for H2S in a five-component
Figure 4. PK vs. pressure plot for H2S in a five-component mix-
mixtureln-pentane quasi-binary system.
tureln-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-pentane and 0.3% for C 0 2 and ethane. 0.d. column packed with 80/100-mesh A 6 f t long Porapak Q was utilized to effect the separation. A thermal conductivity detector was used. The signal from the detector was integrated and reported automatically. Materials. n-Pentane, research grade, 99.96 mol %
pure, was provided by Phillips Petroleum Co. No detectable 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-componentgas 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
689 1034 1379 1710
5.7007 3.3078 2.1433 1.2701
2.0175 1.3751 1.1564 1.2898
1.6831 1.1076 0.8282 0.6864
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
2.83 2.41 1.85 0.98
3.39 2.99 2.59 1.85
1.198 1.242 1.396 1.879
13.667 11.684 8.566 3.958
100 150 200 250 300 334
689 1034 1379 1724 2068 2303
6.7986 4.3238 2.9473 2.1037 1.5011 1.2042
2.3663 1.7000 1.3238 1.1550 1.1431 1.2776
2.2255 1.5033 1.0949 0.8829 0.7426 0.7183
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 4 1 0.025 50 0.3712 0.1231 0.03879
2.87 2.54 2.23 1.82 1.31 0.94
3.05 2.88 2.69 2.38 2.02 1.68
1.063 1.131 1.209 1.308 1.539 1.779
12.260 10.779 9.141 7.299 4.883 3.244
100 150 200 300 400 446
689 1034 1379 2068 2758 3075
8.1840 5.1262 3.7528 2.1873 1.3655 1.1468
2.9213 1.9741 1.5799 1.1842 1.1490 1.2588
2.7875 1.8077 1.3497 0.9480 0.7515 0.7391
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
2.80 2.60 2.38 1.85 1.19 0.91
2.94 2.84 2.78 2.31 1.82 1.55
1.048 1.092 1.172 1.249 1.529 1.705
11.192 10.337 9.309 6.697 3.741 2.631
100
150 200 300 400 500 557
689 1034 1379 2068 2758 3447 3840
9.6279 6.2363 4.5298 2.8173 1.8956 1.3602 1.1694
3.4877 2.4029 1.8756 1.3712 1.1478 1.1204 1.1992
3.2477 2.1372 1.7256 1.1718 0.8905 0.7820 0.7844
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
2.76 2.60 2.42 2.05 1.65 1.21 0.98
2.96 2.92 2.63 2.40 2.13 1.74 1.49
1.074 1.124 1.087 1.170 1.289 1.433 1.529
10.298 9.393 8.902 7.196 5.307 3.525 2.559
100 150 200 300 400 497 600 659
689 1034 1379 2068 2758 3427 4137 4544
11.0899 7.1163 5.1854 3.3252 2.3063 1.7313 1.3462 1.1805
4.1628 2.8055 2.1489 1.5571 1.2482 1.1262 1.1140 1.1294
3.8135 2.5766 1.9632 1.3458 1.0751 0.8891 0.7944 0.7948
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
2.66 2.54 2.41 2.14 1.85 1.54 1.21 1.05
2.91 2.76 2.64 2.47 2.15 1.95 1.69 1.49
1.092 1.089 1.095 1.157 1.161 1.267 1.402 1.421
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 150 1034 0.295 9 200 1379 0.456 8 250 1724 0.766 7 100 150 200 250 315
689 1034 1379 1724 2172
0.144 2 0.223 7 0.314 7 0.4259 0.675 5
0.003 843 0.005 361 0.007 151 0.009020 0.012 45
0.001 517 0.002 328 0.003 387 0.003790 0.004 310
0.002 388 0.8161" 0.9767 0.003 810 0.6872" 0.9751 0.005035 0.5435" 0.9730 0.005 490 0.2481" 0.9644 T = -10.007 "C, 13.987 O F 0.008699 0.002 704 0.8391 0.9742 0.012 58 0.004082 0.7523 0.9734 0.017 72 0.005 140 0.6526 0.9722 0.02047 0.006088 0.5345 0.9711 0.023 73 0.006459 0.2775 0.9675
100 150 200 300 350 406
689 1034 1379 2068 2413 2799
0.127 3 0.177 1 0.2507 0.396 7 0.505 0 0.676 4
0.003 274 0.004 590 0.006064 0.008 727 0.01040 0.012 50
0.000 901 7 0.001 445 0.001 915 0.002 822 0.003 840 0.004043
0.007 275 0.01063 0.014 59 0.02044 0.023 07 0.024 56
T = 0.028 "C, 32.050 O F 0.002 070 0.8593 0.9733 0.003 121 0.8032 0.9720 0.004 309 0.7223 0.9716 0.006 213 0.5650 0.9702 0.006693 0.4509 0.9690 0.006 818 0.2757 0.9666
0.01504 0.015 59 0.015 74 0.016 39 0.017 02 0.018 31
0.001 076 0.001 275 0.001 245 0.001 330 0.001 589 0.001 917
0.008 374 0.009 365 0.009 601 0.010 30 0.010 50 0.010 89
0.000584 4 0.000662 7 0.000 737 5 0.000 843 5 0.000 814 2 0.000 921 8
0.001 629 0.001 141 0.001 121 0.001 109 0.001 064 0.001 004
100 150 200 300 400 500 550
689 1034 1379 2068 2758 3447 3792
0.111 7 0.161 2 0.208 3 0.3200 0.470 5 0.6857 0.816 2
0.002 977 0.004 199 0.005 357 0.007 702 0.010 12 0.012 96 0.014 37
0.001 065 0.001 622 0.002 471 0.003 961 0.004 286 0.004881 0.005 296
0.006 962 0.010 26 0.01499 0.021 83 0.023 70 0.026 33 0.027 72
T = +10.017 "C, 50.031 O F 0.002 141 0.8751 0.9703 0.003 228 0.8197 0.9696 0.005072 0.7637 0.9668 0.005 815 0.6400 0.9654 0.007 205 0.4842 0.9671 0.007 619 0.2625 0.9651 0.007 546 0.1289 0.9620
0.015 08 0.015 53 0.016 03 0.016 45 0.016 56 0.017 83 0.019 42
0.001 640 0.001 785 0.002 118 0.002 395 0.002 128 0.002 203 0.002 799
0.009 527 0.010 29 0.012 16 0.013 01 0.011 57 0.011 91 0.013 47
0.000 765 2 0.000 870 7 0.001 113 0.001 009 0.001074 0.001 135 0.001 459
0.002 667 0.002 011 0.001 764 0.001 617 0.001 583 0.001 460 0.001 083
100 150 200 300 400 500 552 604 647
689 1034 1379 2068 2758 3447 3806 4164 4461
0.093 11 0.132 0 0.1786 0.273 6 0.3700 0.515 5 0.5908 0.689 0 0.792 5
0.002 570 0.003 554 0.004 630 0.006 769 0.008 524 0.010 56 0.011 95 0.013 10 0.01441
0.000696 9 0.001 273 0.001 895 0.003 016 0.003 831 0.004 672 0.005 127 0.005 366 0.005 251
0.005 906 0.008 496 0.011 53 0.016 82 0.020 99 0.025 58 0.026 27 0.026 72 0.026 99
T = +20.001 "C, 68.002 O F 0.001 812 0.9014 0.9675 0.002 611 0.8523 0.9677 0.003 694 0.7997 0.9671 0.005 507 0.6943 0.9665 0.006 744 0.5898 0.9656 0.007 957 0.4353 0.9645 0.007 928 0.3579 0.9640 0.007 739 0.2580 0.9630 0.007 578 0.1532 0.9615
0.015 28 0.015 54 0.015 69 0.015 93 0.016 18 0.016 68 0.017 08 0.017 70 0.018 55
0.001 299 0.001 657 0.001 901 0.002 223 0.002 361 0.002 566 0.002 793 0.002 916 0.003 154
0.010 32 0.010 91 0.011 34 0.011 87 0.012 41 0.012 74 0.012 75 0.012 98 0.013 29
0.0009040 0.000961 1 0.000991 3 0.001 171 0.001 211 0.001 342 0.001 348 0.001 401 0.001 468
0.004 671 0.003 485 0.002 948 0.002 293 0.002 165 0.002 151 0.002 186 0.002 011 0.002 024
a
0.004 255 0.006 556 0.009 220 0.013 74
0.001 405 0.002 481 0.003 535 0.004 521
0.008655 0.013 70 0.01875 0.022 38
0.014 70 0.015 56 0.016 81 0.022 84
0.001 171 0.001 411 0.001 623 0.002 449
0.006 469 0.006 868 0.007 442 0.009 273
0.000 367 4 0.000 399 9 0.000449 5 0.000 607 6
0.000406 4a 0.000 303 9" 0.000 297 4O 0.000 257 lo
0.01505 0.015 52 0.01606 0.01665 0.019 26
0.001 434 0.001 489 0.001 735 0.001 912 0.002 318
0.008 312 0.008402 0.008937 0.009 160 0.009 649
0.000564 1 0.000628 7 0.000647 5 0.0006890 0.000806 1
0.000836 3 0.000 591 4 0.000 5240 0.0005308 0.000487 5
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 provided by Phillips Petroleum Co. with minimum purity of 99.96 mol % , and C.P. grade HPSpurchased from Matheson 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 quasibinary 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-richconcentration region over a substantial range of pressures and temperatures. 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 COzand LPG constituents are feasible. They also indicate that the K values of COPand ethane approach one another and cross as the pressure increases, and the relative volatility of C02and 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 COPconcentrations in the liquid phase help to suppress the relative volatility of HPSwith 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 relatively large. The upper pressure range of operation is limited by the high solubility of COPin 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 extractive solvent a t the same liquid rate and that HPS
588
Ind. Eng. Chem. Process Des. Dev., Vol. 25, No. 2, 1986
Table V. K Values and Relative Volatilities of Various 'Key Components" of a Mixture Containing C02, C2Hs,HzS, C3HS,and n -C4Hlowith Toluene pressure K values psis
kPa
c02
HZS
CZH6
CSHE
toluene -4.052 O F 0.153 9 0.000497 gb 0.1050 0.000442 2* 0.089 28 0.000 547 I* 0.1107 0.001 036b n-C4H10
T = -20.029 100 150 200 250
689 1034 1379 1724
5.7861 3.2954 2.1300 1.2579
3.4548 2.3734 1.8232 1.6623
0.7300" 0.5000" 0.4000" 0.4500"
0.7474 0.5013 0.3969 0.4143
100 150 200 250 315
689 1034 1379 1724 2172
6.7559 4.3514 3.0848 2.2801 1.4323
3.9162 2.8950 2.2458 1.8459 1.5470
0.9453 0.6396 0.5123 0.5045 0.5378
100 150 200 300 350 406
689 1034 1379 2068 2413 2799
7.6457 5.4884 3.8755 2.4457 1.9188 1.4290
4.5938 3.3965 2.5956 1.8781 1.6365 1.4648
100 150 200 300 400 500 550
689 1034 1379 2068 2758 3447 3792
8.6867 6.0149 4.6414 3.0169 2.0555 1.4075 1.1786
100 150 200 300 400 500 552 604 647
689 1034 1379 2068 2758 3447 3806 4164 4461
10.3909 7.3311 5.4149 3.5325 2.6097 1.8710 1.6317 1.3977 1.2132
IYC02/C2Hg
%02/H*S
%~H~/HzS
%Op/CaHg
OC,
1.67 1.39 1.17 0.76
7.93' 6.59' 5.33c 2.8OC
4.73' 4.75' 4.56' 3.6gC
7.74 6.57 5.37 3.04
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
1.73 1.50 1.37 1.24 0.93
7.15 6.80 6.02 4.52 2.66
4.14 4.53 4.38 3.66 2.88
7.07 6.52 6.12 5.10 3.52
1.1933 0.8824 0.6501 0.4713 0.4138 0.4742
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 0.1216 0.002 360 0.4434 0.135 2 0.003 642
1.66 1.62 1.49 1.30 1.17 0.97
6.41 6.22 5.96 5.19 4.64 3.013
3.85 3.85 3.99 3.98 3.95 3.09
6.64 6.23 5.89 4.85 4.22 3.22
5.0655 3.6985 2.9923 2.1358 1.6364 1.3758 1.3514
1.5399 1.1005 0.8571 0.6046 0.4965 0.4513 0.5285
1.3684 1.0029 0.8112 0.5960 0.4882 0.4523 0.4859
0.003 048 0.002 453 0.002310 0.002 527 0.003 269 0.005 562 0.008 402
1.71 1.63 1.55 1.41 1.26 1.02 0.87
5.64 5.47 5.42 4.99 4.14 3.12 2.23
3.29 3.36 3.49 3.53 3.30 3.05 2.56
6.35 6.00 5.72 5.06 4.21 3.11 2.43
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
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 0.003687 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
1.75 1.68 1.60 1.50 1.37 1.18 1.14 1.03 0.94
5.57 5.63 5.40 4.80 4.23 3.41 3.00 2.57 2.02
3.19 3.36 3.38 3.19 3.08 2.88 2.62 2.49 2.14
5.95 5.71 5.51 5.01 4.41 3.76 3.36 2.88 2.46
T = +10.017 "C, 50.031 O F
"Extrapolated values from K vs. 1/T plot.
0.357 4 0.269 7 0.2194 0.173 5 0.149 1 0.149 0 0.193 3
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 psia
kPa
coz
100 150 200 250 299 322
689 1034 1379 1724 2062 2220
0.1494 0.2373 0.3201 0.4425 0.6133 0.7456
COZ 5" = -10.007 "C, 13.987 O F 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
100 150 200 250
689 1034 1379 1710
0.1839 0.3128 0.4565 0.7519
0.8161 0.6872 0.5435 0.2481
~~
toluene
T = -20.029 "C, -4.052
specification in the overhead can be more easily reached a t 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
0.999 59 0.999 73 0.999 67 0.999 74
toluene
COP
toluene
0.000807 2 0.OOO 573 3 0.OOO 566 3 0.000 550 2 0.OOO 551 6 0.000 568 8
6.6880 4.2115 3.1222 2.2587 1.6296 1.3404
0.000 948 9 0.000751 6 0.000 832 9 0.000 986 9 0.001 426 0.002 236
O.OO0 406 4
5.4355 3.1961 2.1899 1.3296
0.000 497 9 0.000 442 2 0.000 547 1
OF
0.OOO 303 9 0.OOO 297 4 0.000 257 1
0.001 036
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 demonstrate the 'proof of correlation".
Ind. Eng. Chem. Process Des. Dev., Vol. 25,
No. 2, 1986 589
L
i
i
b
0
20°C
0
10°C
I h
I
0,
I
1
1
1
l
- 5 -
22G
3C
300 4 0 C 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.
i
3 -
-d
C.3CC21 '00
I
i50
1
200 PQESSURE
I
300
1
i
1
420 5CC i C 0
1
, PSlA
Figure 7. K value vs. pressure plot for C3H8, n-C4HIo,and toluene in a five-component mixture/toluene quasi-binary system.
c
-20cc e - 0°C
4
[ .:.;.. __
3.
E c-o L .;;:;;
50
zoo
I
0
I 0
c0
-
20°C
0
300
I
cot,
,
4cc " 7 ~
1
PRESSURE, "SIA
Figure 6. K value vs. pressure plot for COz, C2He, and H2S 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-
vided research grade ethane, propane, n-butane, and npentane. 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 Mixtures-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 Mixtures-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), 135. Mundis, C. J.; Yarborough, L.; Robinson, R. L., Jr. Ind. Eng. Chem. Process Des. Dev. 1977, 16 (2), 254. Yarborough. L. J. Chem. Eng. Data 1972, 1 7 ( 2 ) , 129.
Received for review June 27, 1985 Revised manuscript received August 9, 1985 Accepted October 21, 1985
