Study On Performance Of Vertical Roller Mill Pulverizer Based On Discrete Element Method

Vertical roller mill is a kind of efficient equipment,who can be used for fine grinding,drying,grinding,powder selection,conveying.Further more,it can grind various different strength,hardness and water content of materials.Vertical roller mill is not only widely used in coal powder preparation,but also widely used in cement,chemical,coal and electric power sectors.At present,the problems of low grinding efficiency and roller disc wear of vertical roller mill need to be solved.In order to improve the performance of the vertical roller mill,the key parameters of the grinding device are calculated and analyzed in this paper.The grinding mechanism is studied based on the theory of material layer crushing.The grinding process is simulated by discrete element.The main research contents are as follows:(1)The relevant theories of the vertical roller mill were studied,and the key parameters of the grinding device(the form of the roller plate,the size of the roller plate,the particle size of the material,the shape of the material,the clamp Angle,the thickness of the material layer,the speed,the roller pressure)were analyzed and calculated.The calculation methods of the roller pressure were mainly derived and compared.Based on the theory of comminution of material layer,the changing law of material bed in the grinding process of vertical roller mill is analyzed,and the formula of distribution of compressive stress in comminution chamber is derived.Through the theoretical analysis,the mathematical model affecting the grinding performance of vertical roller mill is established.(2)Using the method of combining experiment and simulation,based on the factor experiment design,the contact parameters of coal material and vertical roller mill are calibrated,and these parameters are applied to the subsequent simulation.The numerical simulation of grinding process was carried out by using discrete element software,and the changes of particle velocity,kinetic energy,collision times,force,torque and wear of vertical roller mill were analyzed.(3)The level of each factor was determined by single factor simulation test.Based on the dm-workbench coupling orthogonal test,the influence of each grinding parameter(the form of roller disc coordination,the number of grinding rollers,the rotation speed,the material size and the material shape)on the grinding performance was mainly considered,and the comprehensive evaluation formula of the grinding performance of vertical roller mill was proposed,and the regression analysis and parameter optimization of the simulation test data were carried out.(4)Based on the existing experimental conditions,the effects of particle size,Angle between axis and horizontal of grinding roller and the speed of grinding disc on the grinding effect were analyzed.The box-benhnken response surface method was adopted to design the experiment.The product sieve penetration rate was taken as the response factor to analyze the three influencing factors,and the experimental results were compared with the simulation results.Based on the theory,simulation and experiment,this paper studies the mechanical behavior of the material in the grinding process and its influence on the vertical roller mill,and analyzes the relationship between different parameters and the grinding performance,which has certain reference significance for improving the performance and output of the vertical roller mill in the actual production.Figure[72]table[30]reference[116]...