COMPUTATIONAL FLUID-DYNAMICS MODELING OF AN ENTRAINED FLOW BIOMASS GASIFIER

A mathematical model, based on the Computational Fluid Dynamics packag e CFX4, has been developed to study the flow within an entrained flow biomass gasifier. The gasifier is designed to convert sawdust and chop ped cotton gin trash into a low calorific value gas which can be burne d in a modified engine to run a generator. Calculations of the flowfie ld are performed using the standard k-epsilon model and a Differential Reynolds Stress Model (DSM). In line with current thinking, it is sho wn that the k-epsilon model gives unphysical results for complex swirl ing flows, whereas the DSM model performs well. Particle tracking was performed to determine typical trajectories for the biomass and char a nd the results used to determine means of avoiding slagging in the gas ifier base. The simulations have proved to be very useful to the desig ners who are now using the model to optimise the design. (C) 1998 Else vier Science Inc. All rights reserved.