514
Ind. Eng. Chern. Process Des. Dev.
Goc = nuclei growth rate (eq 2) (m/s)
1980, 19, 514-521
Crystallization from Solution", presented at 66th Annual AIChE Meeting, Philadelphia, 1973. Larson, M. A., Mullin, J. W., J. Cryst. Growth, 20, 183 (1973). Liu, Y-A., Botsaris, G. D., AIChE J., 19, 510 (1973). Lodaya, K. D., Lahti, L. E., Jones, M. L., Ind. Eng. Chem. Process Des. Dev., 16, 294 (1977). Murray, D. C., Larson, M. A,, AIChE J., 11, 728 (1965). Ottens, E. P. K., Janse, A. H., de Jong, E. J., J. Cryst. Growth, 13/14, 500 (1972). Ottens, E. P. K., de Jong, E. J., Ind. Eng. Chem. Fundam., 12, 179 (1973). Randolph, A. D., Rajagopal, K., Ind. Eng. Chem. Fundam., 9, 165 (1970). Randolph, A. D., Larson, M. A., "Theory of Particulate Processes", Academic Press, New York, 1971. Randolph, A. D., Sikdar. S . K., Ind. Eng. Chem. Fundam., 15, 64 (1976). Randolph, A. D., Koontz, S.,"Effects of Habit and Nucleation Modifiers In Crystallization of Sodium Tetraborate Decahydrate", presented at 69th Annual AIChE Meeting, Chicago, 1976. Randolph, A. D., Beckman, J. R., Kraljevich, Z. I., AIChE J., 23, 500 (1977). Rosen, H. N., Hulburt, H. M., Chem. Eng. frog. Symp. Ser. No. 110, 67, 18 (1971). Rousseau, R. W., Woo, R., "Effects of Operating Variables on Potassium Alum Crystal Size Distrlbutions", presented at 84th National AIChE Meeting, Atlanta, 1978. Schierhoiz, P. M., Stevens, J. D., AIChE Symp. Ser. No. 151, 71, 248 (1975). Sikdar, S.K., Randolph, A. D., AIChE J., 22, 110 (1976). Sikdar, S. K., Ore, F., Moore, J. H., "Crystailizatlon of Calcium Sulfate Hemihydrate in Reagent Grade Phosphoric Acid", presented at 84th National AIChE Meeting, Atlanta, 1978. Shor. S. M., Larson, M. A,, Chem. Eng. frog. Symp. Ser. No. 110, 67, 32 (1971). Song, Y. H., Douglas, J. M., AIChE J., 21, 924 (1975). Timm, D. C., Larson, M. A., AIChE J., 14, 452 (1968). Timm, D. C., Cooper, T. R., AIChE J., 17, 285 (1971). van Damme-van Weeie, M. A., in "Crystal Growth: an Introduction", Hartman, P., Ed., North Holland, p 248, 1973. Wey, J. S., Terwilliger, J. P., Glngello, A. D., "Analysis of Silver Bromide Precipitation in a Continuous Suspension Crystallizer", presented at 84th National AIChE Meeting, Atlanta, 1978. Wey, J. S., Terwllliger, J. P., Chem. Eng. Commun., 4, 297 (1980). Youngquist, G. R., Randolph, A. D., AIChE J., 18, 421 (1972).
i = relative kinetic order
j = exponent of magma density (eq 1) KR = nucleation rate constant, no./L s (g/L)I (m/s)' MT = magma density, g/L N = agitator speed, rpm s = supersaturation, g of crystallizing substance/g of water YA, yc = constants in size-dependent growth equations (eq 3 and 2), rn-l E = specific power input, W/kg T = residence time, s 0 = temperature, "C
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Received f o r review January 28, 1980 Accepted April 30, 1980
ARTICLES
Electrochemical Study of Liquid-Solid Mass Transfer in Packed Beds with Upward Cocurrent Gas-Liquid Flow Ghlslalne Delaunay, Alain Storck, Andre Laurent, and Jean-Claude Charpentler' Laboratoire des Sciences du G6nie Chimique, CNRS-ENSIC, 54042 Nancy, France
An electrochemical technique was used for global measurement of overall solid-liquid mass transfer coefficients in upward cocurrent gas-liquid flow through a packed bed under bubble flow and surging flow conditipns. The feasibility of the technique was ascertained and the coefficients were compared with those obtained by other techniques. An energetic correlation has been proposed for both single and gas-liquid flow which extends the range of application of previous works.
Introduction The use of fixed bed reactors operated under cocurrent upflow conditions has widely increased during these past years, especially in the petrochemical industries: coal liquefaction, catalytic hydrodesulfurization, selective hydrogenations, etc. (Shah, 1979). The overall rate of the process may depend either on the chemical reaction kinetics or on the physical gas-liquid and liquid to solid 0196-4305/80/1119-0514$01.00/0
particle mass transfer resistances. However, under certain operating conditions the limit of the process is only located at the diffusional mass transfer resistance near the liquid-solid interface. There are very few data available on the determination of the space_average value of the particle mass transfer coefficient k for upward cocurrent flow in packed beds. The recent works published on the topic together with the 0
1980 American Chemical Society
Ind. Eng. Chem. Process Des. Dev., Vol. 19, No. 4, 1980
515
Table I. Experimental Data Available in the Literature for Liquid-to-Solid Particle Mass Transfer in Gas-Liquid Cocurrent Upward Flow in Packed Beds ~~
column packing reference d,.103, m Mochizuki and 5 X 5 Matsui (1974) cylinders Goto et al. (1975)
E
0.335
2.4-1.1 0.44 0.54 crushed parlicles Kirillov and 8-30 spheres; Masamanyan 12 K 12 (1976) Raschig rings Specchia et al. 6 X 6 (1978) cylinders Colquhoun-Lee 6 spheres; and Stepanek 6 X 6 (1978) cylinders present work 4 sphleres 0.37
0.101, m 8.7 2.58
10 square
8 5 4.5
superficial velocity
2.102, m
method electrochemical one single active particle 1.2- dissolution, 4.1 naphthalene
liquid liquid, cm/s gas, cm/s NaOH 0.05 < U L
