CFD-DEM Simulation Of Gas-Solid Flow In Transfer Chute

Bulk transfer system is widely used in mining,metallurgy,coal,chemical and other fields.However,due to the drop in the transfer point,the transfer process is prone to generate a large amount of dust,resulting in a dangerous working environment.In order to study the escape law of dust in mesoscale,the CFD-DEM(Computational Fluid Dynamics-Discrete Element Method)method based on the Euler-Lagrange framework is used to simulate the gas-solid two-phase flow in the transfer chute.Based on the CFD-DEM method,the dust suppression structure of the transfer chute is improved.The main research contents and results of this dissertation are as follows:(1)Through the numerical simulation of the single size particle transfer condition,it is found that the selection of restitution coefficient and drag model has a greater impact on the air velocity at the outlet.By comparing with the experimental results,it is found that the Di Felice Drag model has a higher accuracy when the restitution coefficient is 0.75.At the same time,CFD-DEM simulation can clearly obtain the gas-solid flow state in the transfer chute,and its simulation results are 3% more accurate than the Two-Fluid Model method,especially the maximum value of the outlet air velocity and its location are more consistent with the experimental values.(2)The influence of particle size on the maximum air velocity at the outlet is obtained by orthogonal experiment.When the particle size is larger than 3 mm,the maximum air velocity at the outlet decreases with the increase of particle size;when the particle size is smaller than 3 mm,the maximum air velocity at the outlet increases with the increase of particle size.At the same time,the optimal particle size combination with the minimum experimental error is obtained,and its simulation accuracy is improved by 3% compared with that obtained from the single particle size.(3)By adding a part of the diameter of 200?m particles in the optimal particle size combination to simulate the dust flow,the trajectory of dust in the transfer chute is obtained,which indicates that the dust is the result of the combined action of induced airflow and shear flow.Accordingly,the dust suppression structure of the transfer chute is improved,and the installation angle of the guide plate and the guide plate is studied.The transfer chute H with an inclined flow channel,140° guide plate and a smaller outlet area can significantly reduce the dust dispersion range,reduce the air mass flow rate at the particle outlet by 75%,reduce the maximum air velocity at the outlet by 15%,and reduce the dust emission rate by 42%.Thus,the dust suppression effect of the new designed transfer chute I is greatly improved.