NUMERICAL SIMULATION OF A SEMI-INDUSTRIAL SCALE CFB RISER USING COARSE-GRAINED DDPM-EMMS MODELLING

In this work, a coarse-grained Dense Discrete Phase Model (DDPM) coupled with the Energy-Minimization Multi-Scale (EMMS) drag, was used to simulate the hydrodynamics of a 3D semi-industrial scale Circulating Fluidized Bed (CFB) with Geldart A particles. The effect of particle numbers in a parcel, an important parameter in a coarse-grained approach, was investigated. It was found that when parcel diameter falls into the size range of clusters, simulation results are insensitive to particle number in a parcel and generally agree with the experimental data. Further, a comparison between DDPM and Eulerian Two-Fluid Modelling (TFM) approaches was investigated, both coupled with EMMS and conventional homogenous drag. The simulation results suggested that the effect of meso-scale structures on drag force needs to be considered in both modelling approaches.