Axial flow structure of solids holdup in an 18-m high-density CFB riser based on pressure measurements--颗粒学报PARTICUOLOGY

Su, X., Wang, C., Lan, X., Pei, H., Mao, X., & Gao, J. (2021). Axial flow structure of solids holdup in an 18-m high-density CFB riser based on pressure measurements. Particuology, 54, 116-125. https://doi.org/10.1016/j.partic.2020.05.003

Axial flow structure of solids holdup in an 18-m high-density CFB riser based on pressure measurements

Xin Su, Chengxiu Wang ^*, Xingying Lan, Huajian Pei, Xiaoyang Mao, Jinsen Gao

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China

10.1016/j.partic.2020.05.003

Volume 54, February 2021, Pages 116-125

Received 12 November 2019, Revised 7 April 2020, Accepted 14 May 2020, Available online 20 June 2020, Version of Record 28 January 2021.

E-mail: cwang1277@cup.edu.cn

Highlights

• A solids circulation rate up to 1400 kg/(m² s) is achieved in an 18-m-high riser.

• Axial profiles of the apparent solids holdup are exponential.

• An apparent solids holdup up to 0.2 is observed along the riser.

• The apparent slip velocity reaches 14 m/s at extremely large Gs.

Abstract

The axial flow structure in a high-density CFB riser having a height of 18 m is investigated on the basis of pressure measurements. Solids circulation rates reach 1400 kg/(m² s) at superficial gas velocities of 5–9 m/s and the apparent solids holdup exceeds 0.2, indicating high-density operations have been achieved. The apparent solids holdup increases with the solids circulation rate increasing and/or superficial gas velocity decreasing. Axial distributions of the apparent solids holdup have exponential shapes with denser regions at the bottom and more dilute regions in the upper part. The apparent slip velocity increases with the increasing solids holdup and reaches 14 m/s, showing that there are more opportunities of cluster formation in high-density operation. Furthermore, the apparent slip velocity has a power relation with the apparent solids holdup under a wide range of operating conditions.

Graphical abstract

Keywords

Circulating fluidized bed; Pressure measurement; Flow structure; Solids holdup; Slip velocity

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