GAS–SOLID FLOW MODELLING IN A CIRCULATING FLUIDIZED BED

A. Hussain, F.N. Ani, and A.N. Darus

Keywords

Circulating fluidized bed, computational fluid dynamics, Eulerian model, hydrodynamics, riser, turbulence

Abstract

A numerical parametric study was performed to understand the influence of various riser exit geometries on the hydrodynamics of gas–solid flow in the riser of a circulating fluidized bed (CFB). An Eulerian continuum formulation was applied to both phases. A gas–particle computational fluid dynamics (CFD) model of flow has been investigated using CFD software FLUENT. The turbulence was modelled by the k-ε turbulence model in the gas phase. The simulations were done using the geometrical configuration of a CFB test rig available at the Universiti Teknologi Malaysia (UTM). The computational model was used to simulate the flow behaviour in the riser and exit geometries under same operating conditions. In addition, several numerical experiments were carried out to understand the influence of riser end effects, particle size, gas– solid velocity and solids volume fraction on the simulated flow characteristics. It was found that the k-ε turbulence model predicted good mixing behaviour. The results were found to be useful in interpreting the flows in commercial riser exits. Simulation results has added valuable knowledge to model gas–solid flow in the risers and their exits.

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