Study on particle cluster behavior in the multistage circulating fluidized bed

Abstract

Particle clusters play a significant role in gas-solid flow systems. Cluster motions are experimentally studied in a multistage circulating fluidized bed. Cluster characteristics including spatial distribution, breakup process, and size are discussed. Dynamic parameters (frequency, duration, and time fraction) are also obtained to characterize cluster behavior by employing the digital image analysis method. The results show that cluster motions gradually weaken along radial and axial directions in the enlarged section. Cluster breakup tends to increase in the enlarged section due to gas turbulence and cluster collision. Cluster frequency, duration, and time fraction decrease with the increasing gas velocity but increase with the increasing solid mass flux. Compared with the conventional riser, cluster size reduces in the enlarged section. Furthermore, the analysis results from cluster dynamic parameters indicate that cluster motions are restricted under the low solid loading.

Keywords:

• Cluster
• cluster collision
• pseudo-2D
• digital image analysis
• multistage riser

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by Key Projects of New and Old Kinetic Energy Conversion under Grant ([2020]1220) and the Taishan Scholar Project of Shandong Province under Grant [ts20190937].