An extension of Davidson's theory of bubbles in fluidized beds

Abstract

The two-dimensional form of Davidson's model of a circular gas fluidization bubble in an infinite bed is extended to study a bubble shape closer to that observed experimentally. The gas flow pattern is seen to be significantly altered only close to the rear of the bubble, and study of the theoretical particle flow in that region prompted the successful search for trailing particle vortices reported by Rowe and Partridge. A further extension to beds of finite width shows that, under certain conditions, a bubble on the axis is capable of capturing all gas flow into the bed. The presence of the wall reduces the size of the gas cloud known to form round a bubble when the bubble velocity exceeds the interstitial gas velocity in the undisturbed bed.