Simulation of gas-solids heat transfer in cyclone pyrolyzer using CFD-DEM model--颗粒学报PARTICUOLOGY

Zhang, N., Pan, X., Yang, J., Liu, Q., Lian, W., Du, X., . . . Guan, G. (2024). Simulation of gas-solids heat transfer in cyclone pyrolyzer using CFD-DEM model. Particuology, 85, 155-166. https://doi.org/10.1016/j.partic.2023.03.025

Simulation of gas-solids heat transfer in cyclone pyrolyzer using CFD-DEM model

Nan Zhang ^a, Xueer Pan ^a, Jingxuan Yang ^a *, Qian Liu ^b, Wenhao Lian ^{b c}, Xiao Du ^a, Zhonglin Zhang ^a, Xiaogang Hao ^a *, Guoqing Guan ^d

a College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan, 030024, China
b School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, China
c Shanxi Jinke Technology Service Company Limited, Taiyuan, 030000, China
d Laboratory of Energy Conversion Engineering, Institute of Regional Innovation (IRI), Hirosaki University, 3-Bunkyocho, Hirosaki, 036-8561, Japan

10.1016/j.partic.2023.03.025

Volume 85, February 2024, Pages 155-166

Received 24 January 2023, Revised 25 March 2023, Accepted 31 March 2023, Available online 20 April 2023, Version of Record 3 May 2023.

E-mail: yangjingxuan@tyut.edu.cn; xghao@tyut.edu.cn

Highlights

• Gas-solids heat transfer process of cyclone pyrolyzer is analyzed.

• Heating rate within the cyclone pyrolyzer is 4 times higher than that in downer.

• Higher heat transfer rate is shown in the natural vortex length region.

• A significant inlet gas velocity can yield a maximum temperature of coal particle.

Abstract

Fast heat transfer in the pyrolyzer can increase the yield of pyrolysis gas and tar, and improve the quality of tar. Compared with the downer pyrolyzer, the cyclone pyrolyzer can simultaneously achieve high solids holdup and violent turbulence, and correspondingly faster heat transfer. In this work, the heat transfer behavior in the cyclone pyrolyzer is specifically studied using the computational fluid dynamics-discrete element method. The simulation results reveal that the gas-solids heat convection contributes mainly to the heat transfer process, and the heat radiation and conduction are relatively small and almost negligible, respectively. Compared with the downer pyrolyzer under the same operating conditions, the heating rate is significantly increased in the cyclone pyrolyzer. By analyzing the flow characteristics in the cyclone pyrolyzer, it is found that the region of high convective heat transfer rate coincides with that of natural cyclone length. Additionally, the final coal temperature increases with the increase of gas velocity and exists a maximum value. These results can offer some qualitative understanding of the heat transfer behavior in the cyclone pyrolyzer.

Graphical abstract

Keywords

Cyclone pyrolyzer; Rapidly heating; Heat convection; Natural cyclone length; CFD-DEM

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