化学工学会英文誌 Journal of Chemical Engineering of Japan, vol 31 no 6 pp 950-959 (1998)

Elutriation of Fine Particles from a Vortexing Fluidized Bed
渦動型流動層からの微粒子の飛び出し

CHIEN-SONG CHYANG, HOU-PENG WAN AND Yl-CHEN LIU 

Department of Chemical Engineering, Chung Yuan Christian University, Chung-Li, Taiwan, R.O.C.

Keywords: Elutriation, Particle Size Distribution (PSD), Fine Particle Concentration, Terminal Velocity, Vortexing Fluidized Bed (VFB)

A systematic investigation of elutriation of particles is reported in the cold model of bubbling fluidized bed (BFB) and vortexing fluidized bed (VFB) of 0.19 m diameter and 4.0 m height. Glass beads were used as the fluidized material. The diameter of the coarse particles was 545 uim, the diameter of the fine particles used for the elutriation test ranged from 49 to 194 um. The results indicate that the specific elutriation rate constant (K_*) is a function of the initial concentration of elutriated fine particles. The minimum value of K_* is obtained when the initial concentration of elutriated fine particles is reached 16 wt% in a BFB system. Based on the experimental data obtained from the BFB, a correlation is presented to estimate the K_*. The K_* is found to be a function of the particle terminal velocity, gas density, and modified Froude number (Fr*). For a wide particle size distribution (PSD) system, a new parameter, called particle size distribution factor, r, is introduced to describe the specific elutriation rate constant of wide PSD elutriated fine particles. A method to estimate the specific elutriation rate constant of a multi-component system by using the specific elutriation rate constant of each component obtained from a binary particle mixture system is also presented in this study.