Numerical Simulation Of Gas-solid Two-phase Flow In A Novel Integral Multi-nozzle Spout-fluidized Bed

In this paper,a kind of integral multi-nozzle spout-fluidized bed structure is presented,without the need of bypass supply auxiliary equipment,it can effectively eliminate the cone flow dead zone in the spouted bed,strengthen the gas-solid phase transfer process in the spouted bed,and make the gas-solid two-phase flow state in the spouted bed optimized.On the basis of gas-solid two-phase fluid dynamics,an Euler dual-fluid model(TFM)was used to simulate the gas-solid two-phase flow in an integral multi-nozzle spout-fluidized bed.The distribution of particle velocity and concentration in the bed was obtained by numerical simulation.The numerical simulation results show that the gas-solid two-phase flow in the whole multi-nozzle spout-fluidized bed is more stable than that of 5s,and a stable wave-like section cloud is formed.Compared with the conventional cylindrical cone spouted bed,the integral multi-nozzle spout-fluidized bed can not only produce the particle local fluidization effect at the cone of the bed,it can effectively eliminate particle flow dead zone,strengthen the two-phase mixing and movement of gas and particle in spouted bed and annulus,and omit auxiliary equipment of bypass gas supply.The influence of key parameters such as number of side seams and slit width on gas-solid two-phase flow in a multi-nozzle spout-fluidized bed was analyzed.The results show that when the side slit width is 3mm and the dimensionless slit width δ/D_i is 0.125.Based on the analysis of the radial distribution of particle volume fraction,particle velocity and the relative standard deviation of uniformity evaluation index,it is concluded that the optimal flow distribution is obtained when the number of slits is 4.The diameter of the main nozzle of the multi-nozzle spout-fluidized bed is set to 24 mm.When the number of side-seams is 4,the dimensionless gap width δ/D_i = 0.208(width 5mm)The particle velocity is the most uniform along the radial direction,showing the best particle distribution state.The overall volume fraction of the annular zone particles in the radial direction is the most uniform,showing the best particle distribution.The effect of particle filling height on the gas-solid two-phase flow in a multi-nozzle spout-fluidized bed was analyzed.The calculation results show that: the particle volume fraction is the smallest in the gas incident nozzle,with the increase of the radial distance increases first and then decreases,the particle volume fraction along the radial distribution in the h=0.325 m bed is the smallest,and the relative standard deviation CV is the smallest,which shows that the particle velocity flow field is the highest uniformity and the particle handling quantity is The bed can be used most effectively.