I n d . Eng. Chem. Res. 1987,26, 296-299
296
U, = superficial velocity of the wall phase, (m3of phase/m2 of bed)/s U,, = rise velocity of a single bubble, m/s U, = superficial velocity of the main dense phase, (m3 of phase/m2 of bed)/s UGB= superficial gas velocity in the bubble phase, (m3 of gas/m2 of bed)/s UG, = superficial gas velocity in the cloud wake phase, (m3 of gas/m2 of bed)/s Usi = superficial solids velocity in drift phase, main dense phase, and wall phase, i = 1-3, (m3of solids/m2 of bed)/s u, = linear velocity of the main dense phase, (m3of phase/m2 of phase)/s u, = linear velocity of the wall phase, (m3 of phase/m2 of phase) / s W = weight of tracer added at the top of the bed, m y = axial distance measured from the top of the bed, m Greek Symbols ai= constants defined in text, i = 1-3 pi = constants defined in text, i = 1-3 tmf = voidage at incipient fluidization tB = volume
fraction of bubbles in the bed, m3 of bubble/m3 of bed tz = volume fraction of main dense phase, m3 of phase/m3 of bed t3 = volume fraction of wall phase, m3 of phase/m3 of bed T~ = residence times of drift phase, main dense phase, and wall phase defined in text, i = 1-3, s
L i t e r a t u r e Cited ACSL Paper 3, CSIRO, Division of Computing Research Simulations, Australia, 1974. Avidan, A.; Yerushalmi, J. AIChE. J . 1985, 31(5), 835-841. Bailie, R. C. Proc. Int. Symp. Fluid. 1967, 322-333. Bart, R. Ph.D. Thesis, M.I.T.; Cambridge, MA, 1950. Gilliland, E. R.; Mason, E. A. Ind. Eng. Chem. 1952, 44, 218. Gwyn, J. E.; Moser, J. H.; Parker, W. A. CEP Symp. Ser. 1970, 66(101), 19-27. Hull, R. L.; von Rosenberg, A. E. Ind. Eng. Chem. 1960, 52(12), 989-992. Ishida, M.; Wen, C. Y. AIChE Symp. Ser. 1973, 128(69), 1-7. Kunii, D.; Levenspiel, 0. Ind. Eng. Chem. Fundam. 1968, 7, 446. Latham, R.; Hamilton, C.; Potter, 0. E. Br. Chem. Eng. 1968,13,666. May, W. G. Chem. Eng. Prog. 1959, 55(12), 49. Potter, 0. E. In Fluidization; Davidson, J. F., Harrison, D., Eds.; Academic: New York, 1971; pp 293-381. Reman, G. H. Chem. Ind. (London) 1955, 46. Singer, E.; Todd, D. B.; Guinn, V. P. Ind. Eng. Chem. 1957, 49(1), 11-19. Sitnai, 0. Ind. Eng. Chem. Process. Des. Deu. 1981, 20, 533-538. Sitnai, 0.;Dent, S. C.; Whitehead, A. B. Chem. Eng. Sci. 1982,37(9), 1430-1432. Stephens, C. K.; Sinclair, R. J.; Potter, 0. E. Powder Technol. 1967, 1, 157. van Deemter, J. J. Proc. Int. Symp. Fluid. 1967, 1.
Receiued for reuiew December 6, 1985 Accepted August 25, 1986
Multicomponent Vapor-Liquid Equilibria Measurements for the Development of an Extractive Distillation Process for the Processing of Gas Issuing from a C 0 2 Enhanced Oil Recovery Project Jane H. Hong and Riki Kobayashi* Department o f Chemical Engineering, Rice University, Houston, Texas 77251
This paper provides vapor-liquid equilibria data for t h e design of t h e upper section of the all-important column treating the stabilized feed gas from COzenhanced oil recovery (EOR) projects. Again, t h e extractive agent is represented by n-pentane. The simulated feed gas containing the methane, liquified petroleum gas (LPG) components, and H2S is added t o n-pentane t o form quasi-binary mixtures. A comparison of t h e K values obtained by the addition of methane t o an otherwise similar methane-free gas shows t h a t the effect of methane on the K values of the other constituents becomes increasingly pronounced as t h e pressure increases. H2Sis an exception, since its K values remain relatively unaffected by methane. The use of n-pentane and toluene as extractive solvents to break the COZ-CzH6azeotropes for the design of COz fractionation processes has recently been published (Hong and Kobayashi, 1986a, 198613). This paper is the third in a series of studies t o provide vapor-liquid equilibria (VL-E) data for the design of the demethanizer column. V-L-E data for multicomponent mixtures containing hydrocarbon and nonhydrocarbon components have been reported by Yarborough (1972). K values and COz solubility data of C1-C02-C2-C3-n-C4 mixtures over a wide range of temperatures, pressures, and C02 concentrations were reported by Bergman and Yarborough (1981). This study is concentrated on determining the effects of methane on the V-L-E behavior of COz-rich enhanced oil recovery (EOR) gas mixtures.
The experimental conditions and the composition of the COz-richgas mixture were prepared in such a way that the direct comparison of the K values of each component and the relative volatilities of the “key components” in methane and methane-free systems is possible, as shown in Figures 1-3. Experimental Details The experimental equipment and procedure are essentially the same as discussed in the previous studies (Hong and Kobayashi, 1986a, 198613). With the exception of methane, the purity of each component of the gas mixture has also been described previously (Hong and Kobayashi, 1986a, 1986b). Ultrapure methane was purchased from Matheson Gas Co., with a stated purity of 99.97 mol % .
0888-5885/87/2626-0296$01.50/0 0 1987 American Chemical Society
Ind. Eng. Chem. Res. Vol. 26, No. 2, 1987 297 1
I
I
-WITHCHq
I
1
I
---WTHOUTC&
PRESSURE, PSlA
Figure 3. K value vs. pressure plot for H2S in a six-component CH,, C02-rich gas mixtureln-pentane quasi-binary system, showing the effect of CHI in the gas mixture.
100
200
300 400
600 800
PRESSURE, PSlA Figure 1. K value vs. pressure plot for CHI, COP, and C2H, in a six-component CH,, COz-rich gas mixtureln-pentane quasi-binary system, showing the effect of CH, in the gas mixture.
Table I. Composition of Six-Component CHI, C0,-Rich Gas Mixture component gas composition mol fractions 0.142 0 0.817 2 0.01400 0.004 963 0.015 13 0.006714 Normalized compositions.
thermal agitation for a week and then the composition was determined by gas chromatography.
-
100
200 300 400 600 80 PRESSURE, PSlA
Figure 2. K value vs. pressure plot for C3H8, n-C4HIo,and n-pentane in a six-component CH,, COz-rich gas mixtureln-pentane quasi-binary system, showing the effect of CH4 in the gas mixture.
The six-component gas mixture which included methane, carbon dioxide, ethane, propane, n-butane, and hydrogen sulfide and the methane-free five-component gas mixture were made in this laboratory. Precalculated amounts (in psia) of each component in the order of nbutane, propane, hydrogen sulfide, ethane, carbon dioxidde, and methane were introduced into an evacuated, constant-volume gas cylinder. The gases were mixed by
Experimental Results and Discussion Table I presents the composition of the gas mixture added to n-pentane to form the quasi-binary system. The methane concentration was set a t a value typical of the methane concentration after breakthrough or the methane COz concentration values representing the stabilized gas compositions during most of the history of the COz EOR project. The mixtures were investigated a t -30.013 "C (-22.023 OF), -20.029 "C (-4.052 OF), -10.007 "C (13.987 OF), 0.028 "C (32.050 OF), and 10.017 O C (50.031 O F ) to pressures well beyond the point where the relative volatility, CY = &02/KC2HB,becomes
