CFD simulation of an agitated gas-fluidized bed: Effects of particle–particle restitution coefficient on the hydrodynamics

Abstract

A gas–solid fluidized bed with a frame impeller was simulated using the computational fluid dynamics (CFD) method that integrated the Eulerian–Eulerian two-fluid model, the kinetic theory of granular flow (KTGF) and the multiple reference frame (MRF) model. The pressure fluctuation used to verify the numerical model depends strongly on the particle–particle restitution coefficient, while the bed pressure drop is independent of it. As the particle collisions become ideal, it reaches the homogenous fluidization regime with non-bubbling, low pressure fluctuations and granular temperatures. Meanwhile, the agitation of the frame impeller improves fluidization quality with reduced bubble diameters. The minimum limit of agitation speed for homogenous fluidization decreases with the increase of particle–particle restitution coefficient, i.e. a high agitation speed is needed to strengthen fluidization for inelastic particles, and the fluidization performs well enough for elastic particles that agitation has little influence.