Discrete Element Simulation Of Flowing For Wet Pulverized Coal In Transfer Station

Transfer station is an important part of modern material conveying equipment.During the transfer process,the material is threw from the head of roller,under the guiding of the bow cup casted into the blanking tube,and dropped down along the blanking pipe wall into downward belt,then shipped to the designated location.Therefore,the material transfers efficiency and the service life of the transfer station affected by the structure inside of the bow cup and the design quality of the blanking pipe directly.In the study of the transfer process,domestic and foreign scholars often do not take the viscosity in the certain degree of moisture into consideration which plays a signify cant role in the transfer process.Therefore,it is necessary to study the influence of viscous materials on the transport process from the perspective calculation,experimental study and numerical simulation combined with numerical simulation,the paper works from the following aspects:(1)Generally,the average particle size of the viscous material is at the micron level and the cohesive force among particles is bigger than its gravity.Therefore,in the research of viscous interaction force among particles during the running process,the cohesive force between the particles must be taken into consideration.In this paper,the classical elastic model,JKR model and the liquid bridge model were introduced and the applicable scopes of different model were discussed.On the basis of this,wet coal power is taken as the research object of the viscous material,the particles contact model which was suitable for wet pulverized coal was deducted,and through API the contact calculation model was established in EDEM.(2)The internal friction coefficient between the wet coal particles was obtained by direct shear test,through the inclined plate experiment test,the sliding angle between the steel plate and the wet coal was tested.The moisture content of the experimental sample was tested by electro-thermal constant temperature oven,and through the cave experiment calibration,the viscous parameters between the wet coal particles were verified.(3)The simplified throwing model was established to analysis the influence of the viscosity of wet coal particles on the throwing process,and material discharging trajectory was calculated under the condition of considering viscosity,compared with the simulation results.Under the basic of which,the shape of panel inside of the bow cup was calculated.(4)The simplified model of unloading station was established,and the DEMmicro-contract model and the macroscopic contact parameters of the wet coal were established previously to simulate the transport process of wet coal in blanking tube.The other parameters were ensured unchanged,and then the speed of the upper belt,feed speed,material viscosity and other parameters were changed.Finally,the influence of each parameter on blocking behavior of the falling pipe was analyzed.Calculating out the speed where the material flows out of the blanking tube to predict its influence on impact effect of lower belt.