Hydrodynamic behavior of liquid–solid micro-fluidized beds determined from bed expansion--颗粒学报PARTICUOLOGY

Li, X., Liu, M., & Li, Y. (2018). Hydrodynamic behavior of liquid–solid micro-fluidized beds determined from bed expansion. Particuology, 38, 103-112. https://doi.org/10.1016/j.partic.2017.08.002

Hydrodynamic behavior of liquid–solid micro-fluidized beds determined from bed expansion

Xiangnan Li ^{a b}, Mingyan Liu ^a^b *, Yanjun Li ^{a b}

a Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
b State Key Laboratory of Chemical Engineering (Tianjin University), Tianjin 300072, China

10.1016/j.partic.2017.08.002

Volume 38, June 2018, Pages 103-112

Received 15 December 2016, Revised 4 April 2017, Accepted 22 August 2017, Available online 26 November 2017, Version of Record 2 April 2018.

E-mail: myliu@tju.edu.cn; mingyanliu@126.com

Highlights

• Fluidized beds miniaturization resulted in lower expansion ratio.

• Wall effect at higher particle-to-bed diameter ratio caused higher local voidage.

• Parameters of Richardson–Zaki equation for micro-fluidized bed were correlated.

• Higher minimum fluidization velocities were discussed and correlated.

Abstract

The bed-expansion characteristics of liquid–solid micro-fluidized beds were experimentally studied. Bed columns with inner diameters of 0.8, 1.45, and 2.3 mm were fabricated based on capillaries. Five particle sizes in a range of 22–58 μm were investigated. Bed-expansion curves were plotted using visually recorded bed-expansion heights. The bed expansion and initial fluidization behavior were compared with predictions for conventional-scale beds. Evident differences are reflected in lower expansion ratios and higher minimum fluidization velocities for micro-fluidized beds. These were attributed to the increase in the internal surface area of the particle beds and specific surface area of wall contact. The wall effect for micro-fluidized beds at higher particle/bed diameter ratios caused higher local voidage and an increase in expansion ratio. Correlations for the exponent and proportional coefficient in the Richardson–Zaki equation for micro-fluidized beds were proposed. The minimum fluidization velocities were correlated using a modification of the Ergun equation.

Graphical abstract

Keywords

Micro-fluidized bed; Wall effect; Minimum fluidization velocity; Richardson–Zaki equation; Ergun equation

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