Use of discrete element method simulation in studying fluidization characteristics: influence of interparticle force

Abstract

A discrete element method (DEM) simulation is used to investigate the influence of cohesive interparticle force on the characteristic behaviour of a gas fluidized bed. The cohesive interparticle force is introduced in a general form; it is increased step by step with an increment equivalent to a multiple of the single particle buoyant weight. Simulations were performed using a two-dimensional bed (height 0.2 m , width 0.08 m ) and 4000 particles. The particles used had a diameter of 1 mm and densities in the range 1590– 2650 kg/ m 3 . A carefully formulated strategy is presented for establishing the minimum fluidization and minimum bubbling velocities by DEM simulations. The influence of the magnitude of the cohesive interparticle force on fluidization characteristics is analysed in terms of the change in the ratio of the minimum bubbling to minimum fluidization velocities. Imposing a cohesive interparticle force on particles which are initially Geldart Group D or B is found to bring about Group A characteristics. Most notable of these characteristics is the existence of non-bubbling fluidization for a range of gas velocities between the minimum fluidization velocity and the minimum bubbling velocity.