Study on characteristics of turbulence and combustion by large eddy simulation in fluidized bed

Based on the eddy dissipation concept (EDC) reaction model, the sub-grid reaction model was presented within small eddy and applied to simulate the flow and combustion behavior of coal particles in fluidized bed combustor. By comparing simulation results with sub-grid reaction model, the simulated gas components at the outlet agreed well with experiment data. For volatile homogeneous reactions, the distributions of the sub-grid and total reaction rates as a function of solid concentration were given. The distributions of sub-grid reaction rates have a similar trend with those of total reaction rates. With the increase of particle concentration, volatile homogeneous reaction rates increase. The sub-grid reaction rates are about 22% of the total reaction rates. The carbon heterogeneous reactions with and without sub-grid reaction model as a function of concentration were also given, which have a similar trend. With the decrease of particle concentration, carbon heterogeneous reaction rates increase. The results without the sub-grid reaction model are about 80% of those with the sub-grid reaction model.