Numerical Simulation Of Gas-solid Two Phase Flow And Experimental Study Of Heat And Mass Transfer Between Particles And Gas In CFB Using Naphthalene Sublimation Technique

Circulating fluidized bed (CFB) combustion technology is a new efficient and clean combustion technology. Its application is of great significance to China for the reasons of economical and environmental benefits in the recent years. Great progress has been made in the theory of CFB these years. However the theory is far from perfect up to now. The formulae and date needed for design and application are not consistent and not complete, and the practical performance parameters cannot achieve the design level. These facts show that the basic theory of CFB is especially need to be studied.In the study of heat transfer in CFB, most researchers focus on the heat transfer between the bed and the wall. Few studies have been made in the gas-solid interfacial heat transfer. In this thesis, the influence of primary air, particle size, and particle circulation rate on gas-solid interfacial heat transfer in CFB were investigated, and the influence of secondary air and particle distribution were investigated for the first time by using the naphthalene sublimation technique. From the analyse of the process controlling equations, the dimensionless parameters which affect the Nu number and the Sh number in CFB were obtained, and the experimental dates were further processed to be the more scientific relationship curves of all these dimensionless parameters .In this thesis, by use of k -mmodel and wall function approach the turbulent gas flows in the CFB was simulated. The influence of the secondary air on it was investigated by the compare of the numerical simulation results, and the academic clew was supplied for the further study of numerical simulation. By the use of discrete phase model, the gas-solid two phase flow under different conditions were simulated. The trajectories of particles were obtained, and the influence of secondary air and particle diameter distribution were investigated. And by the compare of experimental results and numerical simulation results, the reference for the further study of numerical simulation of gas-solid two phase flow in CFB was supplied to some degree.