Effects of internals and distributors on the distribution and growth of bubbles in the conventional gas

Zhang, H., Sun, Z., Liu, C., Dong, S., Shao, Y., & Zhu, J. (2021). Effects of internals and distributors on the distribution and growth of bubbles in the conventional gas–solid fluidized bed. Particuology, 55, 1-15. https://doi.org/10.1016/j.partic.2020.10.005

Effects of internals and distributors on the distribution and growth of bubbles in the conventional gas–solid fluidized bed

Haidong Zhang ^a, Zeneng Sun ^b, Chengguo Liu ^b, Shurui Dong ^{b 1}, Yuanyuan Shao ^a *, Jesse Zhu ^{a b *}

a Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, PR China
b Particle Technology Research Centre, Department of Chemical & Biochemical Engineering, The University of Western Ontario, London, Ontario N6A 5B9, Canada

10.1016/j.partic.2020.10.005

Volume 55, April 2021, Pages 1-15

Received 21 August 2020, Revised 27 September 2020, Accepted 20 October 2020, Available online 24 November 2020, Version of Record 3 February 2021.

E-mail: yshao@tju.edu.cn; jzhu@uwo.ca

Highlights

• Internals and sintered distributor result in a more uniform solids distribution.

• More small bubbles and a higher bed expansion are formed by installing internals.

• Smaller-opening internals promote the changeover between dilute phase and dense.

• Sintered plate distributor gives a steady fluidization similar to internals.

• Smaller U_c can be obtained under sintered plate distributor or mesh type internals.

Abstract

The effects of internals and gas distributors on the local dynamics of the bubbles in the conventional gas–solid fluidized bed were studied. Mesh-type internals with different opening areas (50%, 70% and 90%) and different arrangements (two-layer and four-layer); and a sintered plate with a smaller pore size (1 μm) and a perforated plate with a larger pore size as distributors were investigated. Differential pressure drops and local solids holdups were measured under various superficial gas velocities to compare the performances of the different types of internals and distributors. The instantaneous solids holdup signals from the optical fibre probe were used to further examine the local bubble dynamics in detail. Smaller bubbles were found, with the installation of internals or using the sintered plate, resulting in lower pressure drops and a higher bed expansion. Internals with reduced opening area or distributor with smaller pore size further leads to a higher changeover rate between the bubbles and dense phase, both axially and radially, and hence a better gas–solid contacting and an earlier transition to the turbulent flow regime of the bed.

Graphical abstract

Keywords

Gas–solid fluidized bed; Internal; Gas distributor; Bubble dynamics; Flow regime transition

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