Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone--颗粒学报PARTICUOLOGY

Han, S., Yang, J., Zhang, R., Shen, C., Lian, W., Zhang, W., & Hao, X. (2023). Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone. Particuology, 79, 85-94. https://doi.org/10.1016/j.partic.2022.11.004

Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone

Shaoxing Han ^{a 1}, Jingxuan Yang ^{a 1}, Ronghua Zhang ^a, Cong Shen ^b, Wenhao Lian ^c, Wei Zhang ^a, Xiaogang Hao ^a

a College of Chemical Engineering and Technology, Taiyuan University of Technology, Taiyuan, 030024, China
b Avic Xinxiang Aviation Industry (Group) Co, Ltd, Xinxiang, 453002, China
c School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, China

10.1016/j.partic.2022.11.004

Volume 79, August 2023, Pages 85-94

Received 17 August 2022, Revised 7 November 2022, Accepted 8 November 2022, Available online 19 November 2022, Version of Record 24 January 2023.

E-mail: xghao@tyut.edu.cn

Highlights

Abstract

The maximum-efficiency inlet velocity (MEIV) is a ceiling of inlet gas velocity that defines separation efficiency during cyclone design and operation. Experiment and computational fluid dynamics (CFD) simulation exhibited that an apex cone at the dust outlet can break the ceiling and improve the separation efficiency. The phenomenon is closely related to the effect of excessive high inlet gas velocity on the back-mixing escape of fine particles, which is the final result of back mixing, entrainment by the rapid upward airflow, and secondary separation of the inner vortex. In the center of the inner vortex, the airflow rotates slowly and moves rapidly upward. This elevator type of airflow delivers re-entrained particles to the vortex finder. A higher inlet gas velocity accelerates the elevator, causing more entrained particles to escape. This explains the decrease in efficiency at an excessively high inlet gas velocity. When an apex cone is installed at the dust outlet, the back-mixing is significantly weakened because the vortex core is bounded to the center of separator, while the transport effect of rapid upward airflow is weakened by the decrease in axial velocity in the center. Therefore, particle escape is weakened even at excessive high inlet gas velocities. Instead, the centrifugal effect is enhanced because of increased tangential velocity of the gas and particles. Consequently, the ceiling of inlet gas velocity is broken.

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