Hydrodynamics and Solids Mixing Behavior in a Riser with Blunt Internals

Abstract

Abstract: The hydrodynamics and solids mixing behavior in a riser with blunt internals are studied. A
uniformradial distribution for solids fraction and particle velocity achieves near the
internals. The turbulent velocityof particles near the wall increases with the addition of
the internals, with the lateral solids mixing enhancedsignificantly. Probability density
distribution of particle velocity is bimodal in the riser with internals, which issimilar
to that in the conventional riser, indicating that no significant difference in the micro
flow structure existsbetween the riser with internals and the conventional riser. At the
same time, the axial solids mixing behaviorchanges insignificantly with the addition of
internals. These results indicate that the micro flow structure in theriser is very stable,
which changes insignificantly with the change of the bed structure.

Key words: riser, internal, hydrodynamics, solids, mixing behavior

摘要： The hydrodynamics and solids mixing behavior in a riser with blunt internals are studied. A
uniformradial distribution for solids fraction and particle velocity achieves near the
internals. The turbulent velocityof particles near the wall increases with the addition of
the internals, with the lateral solids mixing enhancedsignificantly. Probability density
distribution of particle velocity is bimodal in the riser with internals, which issimilar
to that in the conventional riser, indicating that no significant difference in the micro
flow structure existsbetween the riser with internals and the conventional riser. At the
same time, the axial solids mixing behaviorchanges insignificantly with the addition of
internals. These results indicate that the micro flow structure in theriser is very stable,
which changes insignificantly with the change of the bed structure.

关键词: riser;internal;hydrodynamics;solids;mixing behavior

LIU Hui'e, WEI Fei, YANG Yanhui, JIN Yong. Hydrodynamics and Solids Mixing Behavior in a Riser with Blunt Internals[J]. .

刘会娥, 魏飞, 杨艳辉, 金涌. 内构件存在时提升管内流动及颗粒混合行为研究

[J]. CIESC Journal.

References

[1] 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).
[2] Wei, F., Zhu, J.X., "Effect of flow direction on axial solid dispersion in gas-solids
cocurrent upflow and downflow systems", Chem. Eng. J., 64, 345-352 (1996).
[3] Helmrich, H., Schurgerl, K., Janssen, K., "Decomposition of NaHCO3 in laboratory and
bench scale circulating fluidized bed reactors", In: Circulating Fluidized Bed Technology,
Basu, P., Ed., Pergamon Press, Toronto, 161-166(1986).
[4] Wei, F., Wan, X., Hu, Y., Wang, Z., Yang, Y., Jin, Y., "A pilot plant study and 2-D
dispersion-reactor model for a high-density riser reactor", Chem. Eng. Sci., 56, 613-620
(2001).
[5] Deng, R., Wei, F., Liu, T., Jin, Y., "Radial behavior in riser and downer during the
FCC process", Chem. Eng. Proc.,41, 259-266 (2002).
[6] Zheng, C.G., Tung, Y.G., Li, H.Z., Kwuak M., "Characteristics of fast fluidized beds
with internals", In: Fluidization Ⅶ, Potter, O.E., Nicklin, D., J., Eds., Engineering
Foundation, New York, 275-284 (1992).
[7] Jiang, P., Bi, H.T., Jean, R.H., Fan, L.S., "Baffles effects on performance of
catalytic circulating fluidized bed reactor",AIChE J., 37, 392-1340 (1991).
[8] Jiang, P.J., Inokuchi, K., Jean, R.H., Bi, H.T., Fan, L. S.,"Ozone decomposition in a
catalytic fluidized bed reactor",In: Circulating Fluidized Bed Technology Ⅲ, Basu, P,
Horio, M., Hasatani, M., Eds., Pergamon Press, Oxford, UK,557-562 (1991).
[9] Zhu, J.X., Salah, M., Zhou, Y., "Radial and axial voidage distributions in circulating
fluidized bed with ring-type internals", J. Chem. Eng. Japan, 30 (5), 928-937 (1997).
[10] Zheng, C.G., Tung, Y.G., Zhang, W.N., Zhang, J.G., "Impact of internals on radial
distribution of solids in a circulating fluidized bed", Engineering Chemistry &
Metallurgy,11(4).296-302(1990).(in Chinese)
[11] (4), 296-302 (1990). (in Chinese)11.van der Ham, A.G.J., Prins, W., van Swaaij,
W.P.M., "Hydrodynamics and mass transfer in a regularly packing fluidized bed", In:
Circulating Fluidized Bed Technology Ⅲ,Basu, P., Horio, M., Hasatani, M., Eds., Pergamon
Press,Oxford, UK, 605-611 (1991).
[12] van der Ham, A.G.J., Prins, W., van Swaaij, W.P.M., "Hydrodynamics of a pilot-plant
scale regularly packed circulating fluidized bed", AIChE Symp. Ser., 89 (296), 53-72(1993).
[13] van der Ham, A.G.J., Prins, W., van Swaaij, W.P.M., "A small scale regularly packed
circulating fluidized bed, Part Ⅰ: Hydrodynamics", Powder Technol., 79, 17-28 (1994).
[14] Gan, N., Jiang, D.Z., Bai, D.R., Jin, Y., Yu, Z.Q., "Concentration profiles in fast
fluidized bed with bluff body",J. Chem. Eng. Chinese Univ., 3, 273-277 (1990). (in Chinese)
[15] Wei, F., Yang, Y., Jin, Y., "Effect of internals on hydrodynamics in high-density
riser", J. Chem. Ind. Eng. (China),51, 812-815 (2000). (in Chinese)
[16] Yang, Y., Jia, X., Wei, F., Jin, Y., "Hydrodynamics and lateral gas dispersion in a
high-density circulating fluidized bed reactor with bluff internal", Chinese J. Chem. Eng.,
9(3), 291-196 (2001).
[17] Wei, F., Lin, H., Cheng, Y., Wang, Z., Jin, Y., "Profiles of particle velocity and
solids fraction in a high-density riser",Powder Technol., 100, 183-189 (1998).
[18] Wei, F., Wang, Z., Jin, Y., Yu, Z.Q., Chen, W., "Dispersion of lateral and axial
solids in a cocurrent downflow circulating fluidized bed", Powder Technol., 81, 25-30
(1994).
[19] Zhang, M., Qian, Z., Yu, H., Wei, F., "The solids flow structure in a circulating
fluidized bed riser/downer of 0.42m diameter", Powder Technology, 129 (1-3) 46-52 (2003).
[20] Lin, Q., Wei, F., Jin, Y., "Transient density signal analysis and two-phase micro-
structure flow in gas-solids fluidization", Chem. Eng. Sci., 56, 1-11 (2001).
[21] Levenspiel, O., Chemical Reaction Engineering, 2nd ed.,John Wiley & Sons. Inc., New
York (1972).
[22] Du, B., Wei, F., "Lateral mixing behavior of different particles in a FCC riser", In:
Fluidization X, Engineering Foundation, Kwauk, M., Li, J., Yang, W., Eds., Now York, 197-
204 (2001).