Bubbling behavior of cohesive particles in a two-dimensional fluidized bed with immersed tubes--颗粒学报PARTICUOLOGY

Ma, J., Liu, D., & Chen, X. (2017). Bubbling behavior of cohesive particles in a two-dimensional fluidized bed with immersed tubes. Particuology, 31, 152-160. https://doi.org/10.1016/j.partic.2016.06.005

Bubbling behavior of cohesive particles in a two-dimensional fluidized bed with immersed tubes

Jiliang Ma, Daoyin Liu ^*, Xiaoping Chen

Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing 210096, China

10.1016/j.partic.2016.06.005

Volume 31, April 2017, Pages 152-160

Received 20 October 2015, Revised 27 April 2016, Accepted 3 June 2016, Available online 3 January 2017, Version of Record 9 March 2017.

E-mail: dyliu@seu.edu.cn

Highlights

• Bubbling behavior of large cohesive particles with immersed tubes was studied experimentally.

• Immersed tubes served as framework that promotes defluidization under high cohesive force.

• Immersed tubes reduced the sensitivity of bubble size to cohesive force.

• Bubble number increased first and then decreased with cohesive force.

• Probability profile around tubes depended on both cohesive force and tube location.

Abstract

Fluidization hydrodynamics are greatly influenced by inter-particle cohesive forces. This paper studies the fluidization of large cohesive particles in a two-dimensional fluidized bed with immersed tubes using "polymer coating" to introduce cohesive force, to gain better understanding of bubbling behavior when particles become cohesive and its effect on chemical processes. The results show that the cohesive force promotes bubble splitting in the tube bank region, thereby causing an increase in the number and a decline in the aspect ratio of the bubbles. As the cohesive force increases within a low level, the bubble number increases and the bubble diameter decreases, while the aspect ratio exhibits different trends at different fluidization gas velocities. The difference in the evolution of bubble size under various cohesive forces mainly takes place in the region without tubes. When the cohesive force is large enough to generate stable agglomerates on the side walls of the bed, the bubble number and the bed expansion sharply decrease. The tubes serve as a framework that promotes the agglomeration, thus accelerating defluidization. Finally, the bubble profile around tubes was studied and found to greatly depend both on the cohesive forces and the location of tubes.

Graphical abstract

Keywords

Fluidized bed; Cohesive particle; Immersed tube; Bubble behavior

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