Gas–solid flow in a high-density circulating fluidized bed riser with Geldart group B particles--颗粒学报PARTICUOLOGY

Chang, J., Zhang, K., Zhu, W., & Yang, Y. (2016). Gas–solid flow in a high-density circulating fluidized bed riser with Geldart group B particles. Particuology, 29, 103-109. https://doi.org/10.1016/j.partic.2016.01.010

Gas–solid flow in a high-density circulating fluidized bed riser with Geldart group B particles

Jian Chang ^*, Kai Zhang, Wenqi Zhu, Yongping Yang

Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation, North China Electric Power University, Beijing 102206, China

10.1016/j.partic.2016.01.010

Volume 29, December 2016, Pages 103-109

Received 11 August 2015, Revised 12 January 2016, Accepted 20 January 2016, Available online 12 May 2016, Version of Record 18 November 2016.

E-mail: changjian@ncepu.edu.cn

Highlights

• High solid flux and solid holdup were achieved simultaneously in CFB riser with group B particles.

• Transition point from fast fluidization to dense suspension upflow was determined.

• Solid holdup exhibited a steep parabolic profile in the radial direction of the riser.

• Geldart group B and A particles showed similar slip characteristics in high-density CFB risers.

Abstract

We carried out experiments to explore and characterize the gas–solid flow dynamics of Geldart group B particles in a dense circulating fluidized bed riser. By reducing the pressure drop across the solid control valve and increasing the solid inventory in the storage tank, a high solid circulation rate and a solid holdup above 0.075 throughout the riser were simultaneously achieved. At a solid-to-gas mass flux ratio of approximately 105, flow transitioned from fast fluidization to a dense suspension upflow. In the axial direction of the riser, solid holdup had an exponential profile, increasing with increasing solid circulation rate and/or decreasing superficial gas velocity. From the riser's center to its wall, the solid holdup increased markedly, exhibiting a steep parabolic profile. Increasing the solid circulation rate increased the radial non-uniformity of the solid concentration, while increasing the superficial gas velocity had the opposite effect. In our dense circulating fluidized bed riser, Geldart group B particles had similar slip characteristics to Geldart group A particles.

Graphical abstract

Keywords

Circulating fluidized bed riser; Dense gas–solid flow; High density; High flux; Hydrodynamics; Geldart group B particle

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