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Licensed Unlicensed Requires Authentication Published by De Gruyter October 4, 2016

Evaluation of Mixing and Mixing Rate in a Multiple Spouted Bed by Image Processing Technique

  • Yong Zhang , Wenqi Zhong EMAIL logo , Xiao Rui , Baosheng Jin and Hao Liu


Mixing efficiency is one of the most significant factors, affecting both performance and scale-up of a gas-solid reactor system. This paper presents an experimental investigation on the particle mixing in a multiple spouted bed. Image processing technique was used to extract the real-time information concerning the distribution of particle components (bed materials and tracer particles). A more accurate definition of the tracer concentration was developed to calculate the mixing index. According to the visual observation and image analysis, the mixing mechanism was revealed and the mixing rate was evaluated. Based on these results, the effects of operation parameters on the mixing rate were discussed in terms of the flow patterns. It is found that the detection of the pixel distribution of each component in RGB images is not affected by the interference of air void, thus maintaining good measurement accuracy. Convective transportation controls the particle mixing in the internal jet and spout, while shear dominants the particle mixing in the dense moving region. Global mixing takes place only when the path from one spout cell to the other is open. This path can be formed either by the bubbles or particle circulation flows. The mixing rate is linked to the bubble motion and particle circulation. Provided that there are interactions between the spout cells, any parameters promoting the bubble motion and circulation can increase the mixing rate. Finally, a mixing pattern diagram was constructed to establish the connection between the flow structure and mixing intensity.

Funding statement: The authors gratefully acknowledge financial support from the National Natural Science Foundation of China (Grant No. 51390492, 91334205), A Foundation for the Author of National Excellent Doctoral Dissertation of PR China (201440) and Teaching and Research Fund for Outstanding Young Teachers in Southeast University (2242015R30004).


The authors also acknowledge the provision of a scholarship to Yong Zhang by the China Scholarship Council (CSC) that enabled him to carry out part of the reported work at the University of Nottingham.


1. Aguado, R., Olazar, M., Gaisa´n, B., Prieto, R., Bilbao, J., 2002. Kinetic Study of Polyolefins Pyrolysis in a Conical Spouted Bed Reactor. Ind. Eng. Chem. Res. 41, 4559–4566.10.1021/ie0201260Search in Google Scholar

2. Aguado, R., Olazar, M., San Jose´, M.J., Aguirre, G., Bilbao, J., 2000. Pyrolysis of Sawdust in a Conical Spouted Bed Reactor. Yields and Product Composition. Ind. Eng. Chem. Res. 39, 1925–1933.10.1021/ie990309vSearch in Google Scholar

3. Aguado, R., Olazar, M., San Jose´, M.J., Gaisa´n, B., Bilbao, J., 2002. Wax Formation in the Pyrolysis of Polyolefins in a Conical Spouted Bed Reactor. Energy Fuel 16, 1429–1437.10.1021/ef020043wSearch in Google Scholar

4. Epstein, N., Grace, J.R., 2011. Spouted and Spout-Fluid Beds, Cambridge University Press, Cambridge.10.1017/CBO9780511777936Search in Google Scholar

5. Foong, S.K., Barton, R.K., Ratcliffe, J.B., 1975. Characteristics of Multiple Spouted Beds. Mech. Chem. Trans. Ins. Eng., 7–12.Search in Google Scholar

6. Hu, G.X., Gong, X.W., Wei, B.N., Li, Y.H., 2008. Flow Patterns and Transitions of a Novel Annular Spouted Bed with Multiple Air Nozzles. Ind. Eng. Chem. Res. 47, 9759–9766.10.1021/ie800733nSearch in Google Scholar

7. Huang, H., Hu, G.X., 2007. Mixing Characteristics of a Novel Annular Spouted Bed with Several Angled Air Nozzles. Ind. Eng. Chem. Res. 46, 8248–8254.10.1021/ie070643oSearch in Google Scholar

8. Li, Y.C., Che, D.F., Liu, Y.H., 2012. CFD Simulation of Hydrodynamics in a Multiple-Spouted Bed. Chem. Eng. Sci. 80, 365–379.10.1016/j.ces.2012.06.003Search in Google Scholar

9. Lim, C.J., Watkinson, A.P., Khoe, G.K., Low, S., Epstein, N., Grace, J.R., 1988. Spouted Fluidized and Spout-Fluid Bed Combustion of Bituminous Coals. Fuel 67, 1211–1217.10.1016/0016-2361(88)90040-3Search in Google Scholar

10. Mathur, K.B., Epstein, N., 1974. Spouted Beds, Academic Press, New York.Search in Google Scholar

11. Murthy, D.V.R., Singh, P.N., 1994. Minimum Spouting Velocity in Multiple Spouted Beds. Can. J. Chem. Eng. 72, 235–239.10.1002/cjce.5450720209Search in Google Scholar

12. Murthy, D.V.R., Singh, P.N., 1996. Minimum spouting velocity in multiple spouted beds, in: N.P. Cheremisinoff (Ed.), Mixed-Flow Hydrodynamics: Advances in Fluid Mechanics Series. Gulf Publishing Company, Houston, TX, pp. 741–758.Search in Google Scholar

13. Olazar, M., Aguado, R., Barona, A., Bilbao, J., 2000. Pyrolysis of Sawdust in a Conical Spouted Bed Reactor with a HZSM-5 Catalyst. AIChE J. 46, 1025–1033.10.1002/aic.690460514Search in Google Scholar

14. Olazar, M., Arandes, J.M., Zabala, G., Aguayo, A.T., Bilbao, J., 1997. Design and Simulation of a Catalytic Polymerization Reactor in Dilute Spouted Bed Regime. Ind. Eng. Chem. Res. 36, 1637–1643.10.1021/ie960616qSearch in Google Scholar

15. Olazar, M., San Jose´, M.J., Zabala, G., Bilbao, J., 1994. A New Reactor in Jet Spouted Bed Regime for Catalytic Polymerizations. Chem. Eng. Sci. 49, 4579–4588.10.1016/S0009-2509(05)80042-9Search in Google Scholar

16. Ren, B., Zhong, W.Q., Zhang, Y., Jin, B.S., Wang, X.F., Tao, H., Xiao, R., 2010. Investigation on Flow Patterns and Transitions in a Multiple-Spouted Bed. Energy Fuel 24, 1941–1947.10.1021/ef901449mSearch in Google Scholar

17. Saidutta, M.B., Murthy, D.V.R., 2000. Mixing Behaviour of Solids in Multiple Spouted Beds. Can. J. Chem. Eng. 78, 382–385.10.1002/cjce.5450780213Search in Google Scholar

18. San José, M.J., Olazar, M., Izquierdo, M.A., Alvarez, S., Bilbao, J., 2004. Solid Trajectories and Cycle Times in Spouted Beds. Ind. Eng. Chem. Res. 43, 3433–3438.10.1021/ie030668xSearch in Google Scholar

19. Shen, L.H., Xiao, J., Niklasson, F., Filip, J., 2007. Biomass Mixing in a Fluidized Bed Biomass Gasifier for Hydrogen Production. Chem. Eng. Sci. 62, 636–643.10.1016/j.ces.2006.09.033Search in Google Scholar

20. Zhang, Y., Jin, B.S., Zhong, W.Q., 2008. Experimental Investigations on the Effect of the Tracer Location on Mixing in a Spout-Fluid Bed. Ind. J. Chem. Res. Eng. 6, 1–20.10.2202/1542-6580.1733Search in Google Scholar

21. Zhang, Y., Jin, B.S., Zhong, W.Q., 2009. Experiment on Particle Mixing in Flat-Bottom Spout-Fluid Bed. Chem. Eng. Process. 48, 126–134.10.1016/j.cep.2008.02.012Search in Google Scholar

22. Zhang, S.F., Wang, S.H., Zhao, J.B., 2006. Experimental Study on Hydrodynamics Characteristics of Dobble-Nozzle Rectangular Spouted Bed. Chem. Eng. 34, 33–39.Search in Google Scholar

23. Zhang, Y., Zhong, W.Q., Jin, B.S., Xiao, R., 2012. Mixing and Segregation Behavior in a Spout-Fluid Bed: Effect of Particle Size. Ind. Eng. Chem. Res. 51, 14247–14257.10.1021/ie301005nSearch in Google Scholar

24. van Buijtenen, M.S., van Dijk, W.J., Deen, N.G., Kuipers, J.A.M., 2011. Numerical and Experimental Study on Multiple-Spout Fluidized Beds. Chem. Eng. Sci. 66, 2368–2376.10.1016/j.ces.2011.02.055Search in Google Scholar

Published Online: 2016-10-4
Published in Print: 2017-1-1

©2017 by De Gruyter

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