Determination of Cluster Hydrodynamics in Bubbling Fluidized Beds by the EMMS Approach

Document Type : Original Paper


Oil and Gas Processing Centre of Excellence, School of Chemical Engineering, College of Engineering, University of Tehran, Tehran, Iran


The local solid flow structure of gas-solid bubbling fluidized bed was investigated to identify and characterize the particle clusters. Extensive mathematical calculations were carried out using the energy-minimization multi-scale (EMMS) approach for evaluating cluster properties including the velocity, the size and the void fraction of clusters in the dense phase of the bed. The results showed that by increasing the gas velocity, the void fraction of clusters increases and also the larger portion of solids move in the bed in the form of cluster.  Modeled results were in good agreement with the experimental data reported in literature in terms of the velocity, the size the void fraction of clusters. The results of this study help to comprehend the hydrodynamics of clusters in gas-solid bubbling fluidized beds.


[1] Soong, C. H., Tuzla, K. and Chen, J. C. (1994). Identification of Particle Clusters in Circulating Fluidized Beds, in Circulating Fluidized Beds Technology, A. A. Avidan, Ed., AIChE, New York, 615–620.
[2] Li, H., Xia, Y., Tung, Y. and Kwauk, M. (1991). Micro-visualization of cluster in a fast fluidized Bed, Powder Technol., 66 ,231–235.
[3] Horio, M. and Kuroki, H. (1994). "Three-dimensional flow visualization of dilute dispersed solids in bubbling and circulating fluidized beds." Chem. Eng. Sci., 49, 2413–
[4] Lin, Q., Wei, F. and Jin, Y. (2001). "Transient Density Signal Analysis and Two-Phase Micro Structure Flow in Gas–Solids Fluidization." Chem. Eng. Sci., 56, 2179–2189.
[5] Zhou, B., Li, H., Xia, Y. and Ma, X. (1994). Cluster Structure in a Circulating Fluidized Bed, Powder Technol., 78, 173–178.
[6] Sharma, A. K., Tuzla, K., Matsen, J. and Chen, J. C. (2000). Parametric Effects of Particles Size and Gas Velocity on Cluster Characteristics in Fast Fluidized Beds, Powder Technol., 111, 114–122.
[7] Manyele, S. V., Parssinen, J. H. and Zhu, J. X. (2002). "Characterizing Particle Aggregates in a High-Density and High-Flux CFB Riser." Chem. Eng. J., 88, 151–161.
[8] Cui, H., Mostoufi, N. and Chaouki, J. (2000). "Characterization of Dynamic Gas-Solid Distribution in Fluidized Beds." Chem. Eng. J., 79, 135–143.
[9] Mostoufi, N. and Chaouki, J. (1999). "Prediction of Effective Drag Coefficient in Fluidized Beds." Chem. Eng. Sci., 54, 851–858.
[10] Afsahi, F. A., Sotudeh-Gharebagh, R. and Mostoufi, N. (2009). "Clusters identification and characterization in gas-solid Fluidized bed by the wavelet analysis." Can. J. Chem. Eng., 87, 375-385.
[11] Cocco, R., Shaffer, F., Hays, R., Karri, R. and Knowlton, T. (2010). Particle clusters in and above fluidized beds. Powder Technol., 203, 3-11.
[12] Li, J. and Kwauk, M. (1994). Particle–Fluid Two-Phase Flow: The Energy- Minimization Multi-Scale Method. Metallurgical Industry Press, Beijing, PR China.
[13] Li, J. H., Kwauk, M. and Reh, L. (1992). Role of energy minimization in Gas-solid fluidization. In O. E. Potter and D. J. Nicklin, Fluidization. New York: Engineering Foundation. 83-90.
[14] Zhang, J. Y., Ge, W. J. and Li, H. (2005). "Simulation of heterogeneous structures and analysis of energy consumption in particle–fluid system with pseudo particle modeling." Chem. Eng. Sci., 60, 3091–3099.
[15] Grandell, J. (1976). Doubly Stochastic Poisson Processes. Springer, Berlin, Heidelberg.
[16] Kostinski, A. B. and Jameson, A. R. (1997). "Fluctuation properties of precipitation. Part1: on the deviations of single-size drop counts from the Poisson distribution." J. Atmos. Sci., 54, 2174–2186.
[17] Lackermeier, U., Rudnick, C., Werther, J., Bredebusch, A. and Burkhardt, H. (2001). Visualization of flow structures inside a circulating fluidized bed by means of laser sheet an image processing. Powder Technol., 114, 71–83.
[18] Li, J., Cheng, C., Zhang, Z., Yuan, J., Nemet, A. and Fett, F. N. (1999). "The EMMS model and its application, development and updated concepts." Chem. Eng. Sci., 54, 5409–5425.
[19] Cheng, C., Ge, W. and Li, J. (2005). Multi-scale modeling of the axial heterogeneous structure with the EMMS approach. Internal Reports of Institute of Process Engineering, Chinese Academy of Sciences.
[20] Wang, W. and Li, J. (2007). "Simulation of gas-solid two-phase flow by a multiscale CFD approach: extension of the EMMS model to the sub-grid scale level." Chem. Eng. Sci., 62, 208–231.
[21] Yang, N., Wang, W., Ge, W., Wang, L. and Li, J. (2004). "Simulation of heterogeneous structure in a circulating fluidized bed riser by combining the two-fluid model with the EMMS approach." Ind. Eng. Chem. Res., 43, 5548–5561.
[22] Turton, R. and Levenspiel, O. (1986). A Short Note on the Drag Correlation for Spheres. Powder Technol., 47, 83–86.
[23] Davidson, J. F. and Harrison, D. (1963). Fluidized Particles, Cambridge University Press, Cambridge.
[24] Cai, P., Schiavetti, M., De Michele, G., Grazzini, G. C. and Miccio, M. (1994). Quantitative Estimation of Bubble Size in PFBC. Powder Technol., 80, 99–109.
[25] Ergun, S. (1952). "Fluid flow through packed columns." Chem. Eng. Proc., 48, 1159-1184.
[26] Wen, C. Y. and Yu, H. (1966). Mechanics of fluidization. Chem Engng Prog. Symp. Ser., 62, 100-111.
[27] Gidaspow, D. (1994). Multiphase Flow and Fluidization: Continuum and Kinetic Theory Description. Academic Press, New York.
[28] Xu, G. and Kato, K. (1999). "Hydrodynamic equivalent diameter for clusters in heterogeneous gas-solid flow." Chem. Eng. Sci., 54, 1837–1847.
[29] Bi, H. T. (2002). "Some issues on core-annulus and cluster models of circulating fluidized bed reactors." Can. J. Chem. Eng., 80, 809–817.
[30] Harris, A. T., Davidson, J. F. and Thorpe, R. B. (2002). The prediction of particle cluster properties in the near wall region of a vertical riser. Powder Technol., 127, 128–143.
[31] Mostoufi, N. and Chaouki, J. (2004). "Flow structure of the solids in gas-solid Fluidized beds." Chem. Eng. Sci., 54, 4217- 4227.
[32] Mostoufi, N. and Chaouki, J. (2000). "On the axial movement of solids in gas-solid fluidized beds." Trans. Inst. Chem. Eng., 78, 911–920.
[33] Zuber, N. (1964). "On the dispersed two-phase flow in the laminar flow regime." Chem. Eng. Sci., 19, 897–917.
[34] Gu, W. K. and Chen, J. C. (1998). A model for solid concentration in circulating fluidized beds. In: Fan, L.S., Knowlton, T.M. (Eds.), Fluidization IX. Engineering Foundation, Durago, Colorado. 501–508.
[35] Zou, B., Li, H., Xia, Y. and Ma, X. (1994). Cluster structure in a circulating fluidized bed. Powder Technol., 78, 173–178.