Orientation of spheroidal particles in single jet bubbling fluidized beds

Abstract

Particle shape has a significant effect on the characteristics of fluidized beds due to the anisotropy of non-spherical particles. In particular, particle shape can affect the bubble dynamics such as bubble size, shape and velocity. However, the relationship between bubble dynamics and the orientation of non-spherical particles is not clear. This paper presents a detailed analysis on orientation of spheroids in a gas-solid fluidized bed operated with a continuous central jet. Spheroids with aspect ratios at 0.5 (oblate) and 2 (prolate) are employed to represent disc-like and rod-like particles, respectively. The results show that the orientation of spheroids is directly related to bubble motion. The orientation evolves with bubble progression and prefers to align in the bed horizontally or vertically depending upon the bubble position. Further, frequency distributions of spheroids orienting parallel/perpendicular with fluid flow direction were analysed in terms of several hydrodynamic parameters such as particle position and velocity, and fluid drag force. The results indicate that spheroids have different orientations depending upon the hydrodynamic parameters. The findings obtained from this study can aid to better understand fluidization dynamics associated with non-spherical particles.