循环流化床内颗粒团流动的研究

INVESTIGATION OF PARTICLE CLUSTERS FLOW IN CIRCULATING FLUIDIZED BEDS

循环流化床颗粒相流动具有多尺度效应:单颗粒运动的微尺度、颗粒团运动的介尺度和固相运动的宏尺度。颗粒相流动参数受单颗粒运动和颗粒聚团运动的制约,同时影响气相流动。基于气体分子运动论和颗粒动理学,建立相平均稠密气固两相流流动模型。介尺度模型考虑颗粒团与单颗粒之间、颗粒团与气相之间的动量和能量的传递和耗散。模拟计算颗粒容积份额、速度等参数与实测值相吻合。

Mesoscale structures of clusters and streamers in circulating fluidized beds significantly affect macroscopic hydrodynamic behavior. To model effects of mesoscale structures, the ensemble phase averaging method is extended to derive macroscopic averaged equations and their closures. It is found that drag reduction effects due to mesoscale structures play essential roles in the macroscopic equations of motion. Mesoscale model of particles accounts for the interactions between the single particle and clusters, and particulate phase and gas phase. Simulation results of particle concentration, velocity and granular temperature are in agreement with experimental data.