| The problem of unclear movement of material in the silo during discharge and difficulty in predicting the properties of discharge.In order to solve the above problems,this paper studies the general rules of loading and unloading of the test silo and simulation this process by DEM.The silo side pressure is used to predict the position of silo,and explore the impact of particle size and density on silo discharge.Firstly,This paper explores the movement law and distribution characteristics of coal samples in the test silo,which consists of two aspects: loading and unloading of silo.For the role of loading,the repose angle of the coal sample was determined,and explored the effect of particle size and ash on distribution of coal samples.It was found that the proportion of large particulate material closer to the wall surface increases.There is no significant effect in the distribution of ash.For the role of unloading,small particles have more chance to produce a drop-through phenomenon when the silo is unloaded,and the ash content has less effect on it.Establishing reasonable simulation parameters,simulating silo static side pressure and dynamic side pressure by EDEM,There are two purposes for it:one is to compare the simulation results with the mature theory to verify the rationality of the simulation;the other is to predict the material position in silo through lateral pressure.The result demonstrate that the maximum pressure of the silo is the junction of the column and vertebral in the static condition,the maximum is 1724.13 pa,in the dynamic discharge of the silo,the overpressure coefficient of different positions,the maximum value of 1.95,and generally occurs at the beginning of silo discharge.Verify that predicting material position in silo by lateral pressure is theoretically feasible.Through the MFI quantification of the material flow state when the silo discharge,derivation of the velocity distribution formula "u=2Q(R^2-r^2)/(πR^4)",The trajectory of the particles in the silo is characterized,and the velocity distribution and the discharge volume of the discharge are theoretically deduced and compared with the simulation results,The error is within 5%.Under the completely loading with static conditions,6~13mm material accounts for the largest proportion at the cylinder wall,52.6%;5 groups of particles are marked during the unloading process,-3mm particle move faster than 3~6mm,6~13mm;Finally,materials with different densities are accumulated in the silo,and the density of the discharge port is monitored by simulating the unloading process to predict the material density. |
