Onset of cohesive behaviour in gas fluidized beds: a numerical study using DEM simulation

Abstract

A discrete element method (DEM) is successfully used in simulating the onset of cohesive behaviour in fluidized beds. The observed characteristics of cohesive behaviour include throwing of particles high into the freeboard, lumping of particles, channelling of the bed, and, when the interparticle forces is extremely high, formation of a fixed structure. These characteristics are similar to those observed in physical experiments by various researchers. Numerical experiments using particles of 0.5 and 1 mmm in diameter and 1590-3200 kg/m 3 in density show that the interparticle force at the onset of cohesive behviour is more sensitive to changes in particle diameter than those in particle density. The ratio of the fluid drag to limiting tensile force under packed bed conditions is found to be insensitive to changes in the buoyant weight of a single particle.