An Experimental Investigation on Solid Acceleration Length in the Riser of a Long  Circulating Fluidized Bed

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An Experimental Investigation on Solid Acceleration Length in the Riser of a Long
Circulating Fluidized Bed

HUANG Weixing^a; ZHU Jingxu^b

^a School of Chemical Engineering, Sichuan University, Chengdu 610065
^b Department of Chemical and Biochemical Engineering, University of Western Ontario,
London, N6A5B9, Canada

Received:1900-01-01 Revised:1900-01-01 Online:2001-03-28 Published:2001-03-28
Contact: HUANG Weixing

加长循环流化床提升管中加速段长度的实验研究

黄卫星^a; 祝京旭^b

^a School of Chemical Engineering, Sichuan University, Chengdu 610065
^b Department of Chemical and Biochemical Engineering, University of Western Ontario,
London, N6A5B9, Canada

通讯作者: 黄卫星

Abstract

Abstract: Systematic experimental work was conducted to investigate the solid acceleration length in
a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a
wide range of operating conditions. A more feasible method is proposed to determine the
acceleration length from the measured axial profiles of pressure gradient (or apparent
solid holdup). With this new method and large amount of experimental data, a clear picture
on the variation of the acceleration length with both solid circulating rate and
superficial gas velocity is obtained.It is found that the acceleration length increases
generally with increasing solid flow rate and/or decreasing gas velocity. However, the
trend in variation of the acceleration length with operating conditions are quite different
in different operation ranges. Reasonable explanations are suggested for the observed
variation patterns of acceleration length.

Key words: CFB riser, solid acceleration, acceleration length, axial flow structure, gas-solid flow, solid holdup

摘要： Systematic experimental work was conducted to investigate the solid acceleration length in
a 16m long circulating fluidized bed riser with fluid cracking catalyst particles over a
wide range of operating conditions. A more feasible method is proposed to determine the
acceleration length from the measured axial profiles of pressure gradient (or apparent
solid holdup). With this new method and large amount of experimental data, a clear picture
on the variation of the acceleration length with both solid circulating rate and
superficial gas velocity is obtained.It is found that the acceleration length increases
generally with increasing solid flow rate and/or decreasing gas velocity. However, the
trend in variation of the acceleration length with operating conditions are quite different
in different operation ranges. Reasonable explanations are suggested for the observed
variation patterns of acceleration length.

关键词: CFB riser;solid acceleration;acceleration length;axial flow structure;gas-solid flow; solid holdup

HUANG Weixing, ZHU Jingxu. An Experimental Investigation on Solid Acceleration Length in the Riser of a Long
Circulating Fluidized Bed[J]. .

黄卫星, 祝京旭. 加长循环流化床提升管中加速段长度的实验研究[J]. CIESC Journal.

References

[1] Grace, J. R., Bi, H., "Introduction to circulating fiuidized beds", In: Circulating
Fluidized Beds, Grace, J. R., Avidan, A. A., Knowlton, T. M., eds., Blackie Academic &
Professional, New York, 3－20 (1997).
[2] Berruti, F., Chaouki, J., Godfroy, L., Pugsley, T. S., Patience, G. S., "Hydrodynamics
of circulating fluidized bed risers: a review", Can. J. Chem. Eng., 73, 579－602(1995).
[3] Li, Y., Kwauk, M., "The dynamics of fast fluidization",In: Fluidization, Grace, J. R.,
Matsen, J. M., eds., Plenum Press, New York, 537－544 (1980).
[4] Bai, D., Jin, Y., Yu, Z., Zhu, J., "The axial distribution of the cross-sectionally
averaged voidage in fast fluidized beds", Powder Technol., 71, 51－58 (1992).
[5] Issangya, A., "Flow dynamics in high density circulating fluidized beds", Ph. D.
Thesis, University of British Columbia, Vancouver (1998).
[6] Bai, D., Jin, Y., Yu, Z., "The length of particle acceleration region in fast fiuidized
beds", Chem. Reac. Eng. Technol.(China), 6(3), 34－39 (1990). (in Chinese)
[7] Weinstein, H., Li, J., "An evaluation of the actual density in the acceleration section
of vertical risers", Powder Technol.,57, 77－79 (1989).
[8] Pugsley, T. S., Berruti, F., Godfroy, L., Chaouki, J., Patience, G. S., "A predictive
model for the gas-solid flow structure in circulating fiuidized bed risers", In:
Circulating Fluidized Bed Technology IV, Avidan, A. A., ed., AIChE,New York, 40－47 (1994).
[9] Grbavcic, Z. B., Garic, R. V., Jovanovic, S. D., Rozic, L. S.,"Hydrodynamic modeling of
vertical accelerating gas-solid flow", Powder Technol., 92, 155－161 (1997).
[10] Nieuwland, J. J., Delnoij, E., Kuipers, J. A. M., van Swaaij,W. P. M., "An engineering
model for dilute riser flow", Powder Technol., 90, 115－123 (1997).
[11] Mueller, P., Reh, L., "Particle drag and pressure drop in accelerated gas-solid flow",
In: Circulating Fluidized Bed Technology IV, Avidan, A. A., ed., AIChE, New York,159－166
(1994).
[12] Bai, D., Kato, K., "Saturation carrying capability of gas and flow regimes in CFB", J.
Chem. Eng. Japan, 28 (2),179－185 (1995).
[13] Shimizu, A., Echigo, R., Hasegawa, S., Hishida, M., "Experimental study of the
pressure drop and the entry length of the gas-solid suspension flow in a circular tube",
Int. J.Multiphase Flow, 4, 53－64 (1978).
[14] Li, J., Tung, Y., Kwauk, M., "Method of energy minimization in multi-scale modeling of
particle-fluid two-phase flow", In: Circulating Fluidized Beds Technology Ⅱ, Basu,P.,
Large, J. F., eds., Pergamon Press, Toronto, 89－103(1988).
[15] Fujima, Y., Tagashira, K., Tagahashi, Y., Ohme, S.,Ichimura, S., Arakawa, Y.,
"Conceptual study on fast fluidization formation", In: Circulating Fluidized Bed Technology
Ⅲ, Basu, P., Horio, M., Hasatani, M., eds., Pergamon Press, Toronto, 85－90 (1991).