Effect of particle shape on the hydrodynamics of gas-solid fluidized bed

Abstract

Non-spherical particles are common in industrial applications such as coal gasification and biomass combustion. The present work employs a coupled Computational Fluid Dynamics – Discrete Element Method (CFD-DEM) approach to numerically investigate the particle shape effect on the hydrodynamics of a rectangular gas-solid fluidized bed. The CFD-DEM model capability is tested by comparing the mean horizontal and vertical velocities and pressure drop against the National Energy Technology Laboratory (NETL) experimental data. The effect of different numerical parameters (time step, grid size, discretization technique) on the predicted data is also studied. A grid size of three particle diameters and a 2nd Superbee discretization scheme are selected to run the simulations based on the numerical accuracy and simulation time. Seven different drag models are utilized to model the particle-fluid interaction. Further, simulations are conducted using the Di Felice-Ganser drag model for five different sphericities. A strong relationship between sphericity and fluidization behavior is noted. At the constant superficial gas velocity of 2.19 m/s, the fluidization behavior is changed from bubbling to a turbulent regime when the sphericity decreases from 1 to 0.42.