Abstract
The hydrodynamics of solids (FCC) recycle in a loop-seal (0.08 m) at the bottom of the downcomer (0.08 m-I.D.x4.0 m-high) in a circulating fluidized bed (0.1 m-I.D.x 5.3 m-high) have been determined. Solid flow rate through the loop-seal increases linearly with increasing aeration rate. At the same aeration rate, the maximum solid flow rate can be obtained at a loop-seal height-to-diameter ratio of 2.5. The effects of solid inventory, solid circulation rate and gas velocity on pressure balance around the CFB have been determined. At a given gas velocity and solid circulation rate, pressure drops across the downcomer and loop-seal increase linearly with increasing solids inventory in the bed. At a constant solid inventory, pressure drops across the riser and the downcomer increase with increasing solid circulation rate but decrease with increasing gas velocity in the riser. The obtained solid flow rate has been correlated with pressure drop across the loop-seal.
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References
Basu, P. and Fraser, S. A., “Circulating Fluidized Bed Boiler: Design and Operation”, Butterworth-Heinemann, Boston (1991).
Cho, Y.J., Namkung, W., Kim S.D. and Park, S.W., “Effect of Secondary Air Injection on Axial Solid Holdup Distribution in a Circulating Fluidized Bed”,J. Chem. Eng. Japan,27(2), 158 (1994).
Dries, H.W.A., “Cocurrent Gas/Solids Downflow in Vertical Cat Cracker Standpipes: Effects of Gas Compression and Solids Compaction”,Fluidization, Editors Grace, J. R. and Matsen, J. M., 493 (1980).
Ergun, S., “Fluid Flow Through Packed Columns”,Chem. Eng. Prog.,48(2), 89 (1952).
Knowlton, T. M. and Hirsan, I., “L-valves Characterized for Solids Flow”Hydrocarbon Processing,57, 149 (1978).
Knowlton, T.M. and Hirsan, I. and Leung, L.S., “The Effect of Aeration Tap Location on the Performance of a J-valve”, Fluidization, Editors Davidson, J. F. and Keairns, D.L., Cambridge University Press, 128 (1978).
Knowlton, T. M., “Non Mechanical Solid Feed and Recycle Devices for Circulating Fluidized Bed” CFB Technol. II, Editors Basu, P. and Large, J. F., Pergamon Press, New York, 31 (1988).
Kojabashian, C, “Properties of Dense-phase Fluidized Solids in Vertical Down-flow” Ph.D. Thesis, Massachusetts Institute of Technology, Cambridge, Massachusetts, U.S.A. (1958).
Leung, L. S., Chong, Y. O. and Lottes, J., “Operation of V-valves for Gas-Solid Flow”,Powder Technol.,49, 271 (1987).
Merrow, E., “Linking R & D to Problems Experienced in Solids Processing”,Chem. Eng. Process.,May, 14 (1985).
Namkung, W., Cho, Y. J. and Kim, S. D., “Axial Solid Hold-up Distribution in a Circulating Fluidized Bed”,HWAHAK KONGHAK,32, 241 (1994).
Rhodes, M.J. and Laussman, P., “A Study of the Pressure Balance Around the Loop of a CFB”,Can. J. Chem. Eng.,70, 625 (1992).
Rudolph, V., Chong, Y.O. and Nickiin, D.J., “Standpipe Modeling for Circulating Fluidized Beds” CFB Technol. III, Editors Basu, P., Horio, M. and Hasatani, M., Pergamon Press, New York, 49 (1991).
Yang, W.C. and Knowlton, T.M., “L-valve Equations”,Powder Technol.,77, 49 (1993).
Zenz, F.A., “Maintaining Dense-Phase Standpipe Downflow”,Powder Technol.,47, 105 (1986).
Zhang, J.Y. and Rudolph, V., “Transitional Packed Bed Flow in Standpipes”Can. J. of Chem. Eng.,69, 1242 (1991).
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Kim, S.W., Namkung, W. & Kim, S.D. Solids flow characteristics in loop-seal of a circulating fluidized bed. Korean J. Chem. Eng. 16, 82–88 (1999). https://doi.org/10.1007/BF02699009
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DOI: https://doi.org/10.1007/BF02699009