Particle segregation in fluidised binary mixtures

Abstract

The particle segregation in fluidised beds consisting of different types of binary mixtures is shown to be governed by the same particle transport processes. The segregation behaviour of both “different-density mixtures” and “equal-density mixtures”, two types of system which until now largely have been investigated and modelled separately, have been successfully simulated using the same technique, and assuming the same transport processes to be active in both types of system. Experimental results showing segregation profiles in both types of mixtures, but using particles very much coarser than those normally investigated, are presented. The significance of the particle transport parameters is discussed. A new empirical relation for the bubble wake angle in group B powders has been proposed, and it has been made likely that the rate of material interchange between the wake of a rising bubble and the surrounding bulk is independent of the minimum fluidisation velocity of the bed particles. A discussion of future research seen as useful for better prediction of particle mixing and segregation is provided.