Discrete Element Simulation Study On The Flow Behavior Of Coal Particles In Transfer System

Transportation equipment for bulk materials is widely used in thermal power plants,port transportation,mining,and other fields.As a transfer station for belt transportation equipment,the transfer system plays a vital role in material transportation.However,the unreasonable design of the transfer system leads to problems such as wear,blockage,belt deviation,and dust.Due to the large volume of material transfer equipment,difficult construction,high test cost and time consuming.This kind of problem can be solved by using digital design method-computer numerical simulation technology.In this paper,the dry coal material is used as the experimental object,the material’s density and static friction coefficient are measured through experiments,and the discrete element model of irregular particles and the geometric model of the transport system are established.Using the Plackett-Burman(PB)test and single factor test analysis method,a DEM simulation model was established to simulate the angle of repose formed by the coal accumulation process,and the influence of the contact parameters of the material on the angle of repose was analyzed.The simulation results show that the parameters affecting the angle of repose mainly include coal-coal static friction coefficient,coal-coal dynamic friction coefficient,coal-coal rolling friction coefficient,coal-steel dynamic friction coefficient.The Box-Behnken Design(BBD)experimental design was used to construct a regression model between the angle of repose and the above four parameters.Taking the rest angle obtained from the experiment as the response index,the optimized regression model is solved,and the optimal parameter combination is obtained,which makes the simulation very consistent with the accumulation angle and avalanche angle of the experiment.Through the(PB)experimental design,the physical parameters and contact parameters of the material and the influence of the belt speed on the material discharge trajectory were explored.The results show that the belt speed is the main factor affecting the granular discharge trajectory.Then,through the single factor test,the relationship between the belt speed and the material discharge trajectory is analyzed,and the mathematical model of material discharge trajectory is established.Finally,based on the particle discrete element model obtained above,aiming at the problems of pipeline wear and blocking in the process of bulk transportation of transport system,the hood and transfer pipe with different structural parameters are established.Orthogonal experiments were used to study the effect of the structure of the shroud and the blanking tube on the wear of the transfer pipe,the outlet speed of the material,and the impact strength of the material conveyor belt.Through the analysis of the simulation results,the optimal combination of the parameters of the Transfer pie and the hood is obtained,and the designed structure can meet the requirements of low wear,high exit velocity,and low impact strength.