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Keywords:

  • fluidised bed;
  • agglomeration;
  • discrete element method;
  • solid bridge;
  • elevated pressure

Abstract

Effect of operating pressure on the hydrodynamics of agglomerating gas–solid fluidised bed was investigated using a combination of discrete element method (DEM) for describing the movement of particles and computational fluid dynamic (CFD) for describing the flow of the gas phase. The inter-particle cohesive force was calculated based on a time dependent model developed for solid bridging by the viscous flow. Motion of agglomerates was described by the multi-sphere method. Fluidisation behaviour of an agglomerating bed was successfully simulated in terms of increasing the size of agglomerates. The results showed that increasing the operating pressure postpones de-fluidisation of the bed. Since the DEM approach is a particle level simulation and study about particle–particle interactions is possible, a micro-scale investigation in terms of cohesive force and repulsive force during agglomeration at elevated pressures was done. The micro-scale results showed that although the number of contacts between particles was decreased by increasing operating pressure, stronger solid bridge formed between colliding particles at higher pressures. © 2012 Canadian Society for Chemical Engineering