循环流化床多组分颗粒气固两相流动模型和数值模拟

MODEL AND SIMULATION OF GAS-SOLIDS FLOW WITH WIDE SIZE DISTRIBUTIONS IN CIRCULATING FLUIDIZED BEDS

基于稠密气体分子运动论和颗粒动力学 ,考虑多组分颗粒中颗粒组分与颗粒组分、颗粒组分内颗粒之间的相互作用以及气体与颗粒之间的相互作用 ,提出多组分颗粒非等温颗粒气固两相流动模型 .以颗粒压力、径向分布函数、黏度、颗粒碰撞耗散等耦合各颗粒组分间和颗粒间的相间作用 .采用大涡模拟方法模拟气相湍流流动 .提出了多组分颗粒的径向分布函数计算方法 .对循环流化床上升管中双组分颗粒气固两相流动特性进行了数值模拟 ,模拟结果揭示了上升管中双组分颗粒气固两相流动的环 核流动结构 ,得到了平均颗粒粒径的轴向和径向分布规律 ,计算结果与文献中实验结果相吻合 .

A multi-fluid computational fluid dynamics model was developed with wide size distributions in the riser of circulating fluidized beds. The flow model of particle phases is based on the kinetic theory of dense gases and the kinetic theory of granular flow with unequal granular temperatures between the particle classes. The interactions between particle-particle and gas-particles were considered in the model. Coupling between the particle phases was made through particle pressure, binary radial distribution function, viscosities, particle collision dissipation and conductivities. Turbulent flow of the gas phase was modeled by the large eddy simulation. The expression of radial distribution function of particles was proposed. Simulation results revealed a typical core-annulus flow structure with one gas phase and two solid phases in the riser. Radial and axial segregations of the mean diameter are predicted. The computational results agreed with the experimental data reported in the literature.