Simulation And Experimental Research Of Vertical Screw Conveyor Based On Discrete Element Method

With the growth of port economy,the shipping industry is developing increasingly.In many continuous ship unloading machines,the screw ship unloader is favored by the advantages of economy,environment protection and energy saving.In this paper,the gas solid two phase flow in the vertical screw conveyor is studied and analyzed by the combination of the theory of bulk mechanics,the discrete element method and the simulation and experimental research.The main research contents and results are as follows:(1)Analysis of physical and mechanical properties of bulk materials,at the same time using the granular mechanics and particle swarm theory to analyze the material movement of the vertical screw conveyor in the process of the work to get particle motion equation,which provides the theoretical support for t he designed parameter of the screw conveyor.(2)On the basis of the discrete element method,the coupling method of EDEM software and Fluent software is used to analyze the transmission process of the vertical screw conveyor.The contact collision between particles is simulated by Hertz-Mindlin(no slip)model,and the contact collision between particles and device is simulated by Hertz-Mindlin with Archard Wear model.Particle model is selected by soft sphere model.The coupling simulation of particle and gas is selected by Eulerian-Eulerian method.The drag force model is solved by Ergun and Wen&Yu drag model(Gidaspow model).(3)By using the discrete element method,the material property parameters are determined by EDEM software.Application of EDEM-Fluent coupling simulation analysis of gas-solid two-phase flow in vertical screw conveyor,mainly study on the internal flow velocity field and pressure field,and the motion characteristics of particles under a single working condition,as well as the effect of feed rate,filling rate and screw speed on the particle motion,and the analysis of the wear of spiral blades.The simulation results show that the inlet pressure is less than the standard atmospheric pressure and due to high speed rotation the air flow formed by vortex,which is conducive to the feeding process;when the feed rate is constant,the increase of screw speed increases particle velocity and blade wear.When the screw speed is constant,the change of filling rate has little effect on the conveying efficiency.When filling rate is constant,increasing the screw speed makes all the factors increase obviously.(4)Set up a vertical spiral conveying device corresponding to the simulation model,and according to the simulation condition determine the experiment scheme and test parameters to study the change of particle motion with feed volume,filling rate and spiral speed.The results show that the variation trend of experimental value and simulated value is basically the same.Comparing the influence factors,the relative error is less than 14.2%,which verifies the accuracy and accuracy limitation of simulation.In this paper,the EDEM-Fluent coupling method is applied to simulate the working process of vertical screw conveyor,and its accuracy is verified through experimental research,which provides a scientific basis for optimal design of vertical screw conveyor and reasonable selection of operation parameters.