Numerical analysis of residence time distribution of solids in a bubbling fluidized bed based on the modified structure-based drag model--颗粒学报PARTICUOLOGY

Zou, Z., Zhao, Y., Zhao, H., Li, H., Zhu, Q., Xie, Z., & Li, Y. (2017). Numerical analysis of residence time distribution of solids in a bubbling fluidized bed based on the modified structure-based drag model. Particuology, 32, 30-38. https://doi.org/10.1016/j.partic.2016.09.005

Numerical analysis of residence time distribution of solids in a bubbling fluidized bed based on the modified structure-based drag model

Zheng Zou ^a, Yunlong Zhao ^{a b}, Hu Zhao ^a^b, Hongzhong Li ^a *, Qingshan Zhu ^a, Zhaohui Xie ^a, Yingbo Li ^c

a State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
b University of Chinese Academy of Sciences, Beijing 100049, China
c Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

10.1016/j.partic.2016.09.005

Volume 32, June 2017, Pages 30-38

Received 26 March 2016, Revised 7 September 2016, Accepted 21 September 2016, Available online 13 January 2017, Version of Record 20 April 2017.

E-mail: hzli@ipe.ac.cn

Highlights

• The solids RTD and fluidized structure of BFB were simulated by using CFD.

• The simulated results showed a reasonable agreement with the theoretical value.

• The numerous small peaks on RTD curve were induced by back-mixing and aggregation of particles.

• The low value of t50 resulted in poor contact between phases.

Abstract

The residence time distribution (RTD) of solids and the fluidized structure of a bubbling fluidized bed were investigated numerically using computational fluid dynamics simulations coupled with the modified structure-based drag model. A general comparison of the simulated results with theoretical values shows reasonable agreement. As the mean residence time is increased, the RTD initial peak intensity decreases and the RTD curve tail extends farther. Numerous small peaks on the RTD curve are induced by the back-mixing and aggregation of particles, which attests to the non-uniform flow structure of the bubbling fluidized bed. The low value of t50 results in poor contact between phases, and the complete exit age of the overflow particles is much longer for back-mixed solids and those caught in dead regions. The formation of a gulf-stream flow and back-mixing for solids induces an even wider spread of RTD.

Graphical abstract

Keywords

Fluidization; Residence time distribution; Bubbling fluidized bed; Modified structure-based drag model; Computational fluid dynamics CFD

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