Effect of Acoustic Energy on Fluidization of Ultra-Fine Particle

Abstract

Achieving fine particles to fluidize are very difficult with conventional methods, due to strong inter particle attraction. The difficulty of putting these powders in suspension in the fluidizing gas is related to the cohesive structure and, interparticular force, to the physical forces between the primary particles. Large inter particle forces lead to bed cracking, slugging and channeling, and cause the powder not to fluidize consistently. In this study the fluidization behavior of fume silica and talc of micronic diameter belonging to the group C of Geldart’s classification has been investigated. The basic aim of this research work is to improve the quality of fluidization of fume silica (dp=45μm) and talc (dp=10-75 μm) by applying external source in terms of acoustic field. In addition, effect of acoustic field and variation of frequency on minimum fluidization velocity (Umf) and on minimum bubbling velocity has been found out. It was observed that Umf decreases in presence of acoustic field with homogenous fluidization. The best effect observed at 145dB and 120Hz.Fluidization under acoustic field allows to partly overcoming the adhesive forces between powders. The fluidization behavior has been improved for the highest sound intensity.