Experimental investigation on flow asymmetry in solid entrance region of a square circulating fluidized bed--颗粒学报PARTICUOLOGY

Wang, Z., Sun, S., Chen, H., Deng, Q., Zhao, G., & Wu, S. (2009). Experimental investigation on flow asymmetry in solid entrance region of a square circulating fluidized bed. Particuology, 7(6), 483–490. https://doi.org/10.1016/j.partic.2009.07.004

Experimental investigation on flow asymmetry in solid entrance region of a square circulating fluidized bed

Zhengyang Wang^*, Shaozeng Sun, Hao Chen, Qigang Deng, Guangbo Zhao, Shaohua Wu

Combustion Engineering Research Institute, Harbin Institute of Technology, Harbin 150001, China

10.1016/j.partic.2009.07.004

Volume 7, Issue 6, December 2009, Pages 483-490

Received 9 February 2009, Revised 20 May 2009, Accepted 8 July 2009, Available online 14 October 2009.

E-mail: sunsz@hit.edu.cn

Highlights

Abstract

To study the influence of back feeding particles on gas–solid flow in the riser, this paper investigated the flow asymmetry in the solid entrance region of a fluidized bed by particle concentration/velocity measurements in a cold square circulating fluidized beds (CFB). The pressure drop distribution along the riser and the saturation carrying capacity of gas for Geldart-B type particles were first analyzed. Under the condition of u₀ = 4 m/s and G_s = 21 kg/(m²s), the back feeding particles were found to penetrate the lean gas–solid flow near the entrance (rear) wall before reaching the opposite (front) wall, thus leading to a relatively denser region near the front wall in the bottom bed. Higher solid circulation rate (u₀ = 4 m/s, G_s = 33 kg/(m²s)) resulted in a higher particle concentration in the riser. However the back feeding particles with higher momentum increased the asymmetry of the particle concentration/velocity profile in the solid entrance region. Lower air velocity (u₀ = 3.2 m/s) and G_s = 21 kg/(m²s), beyond the saturation carrying capacity of gas, induced an S-shaped axial solid distribution with a denser bottom zone. This limited the penetration of the back feeding particles and forced the fluidizing air to flow in the central region, thus leading to a higher solid holdup near the rear wall. Under the conditions of u₀ = 4 m/s and G_s = 21 kg/(m²s), addition of coarse particles (d_p = 1145 μm) into the bed made the radial distribution of solids more symmetrical.

Graphical abstract

Keywords

Square circulating fluidized bed; Solid entrance region; Flow asymmetry; Experimental investigation

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