Research For The Wear Model Of Ball And Optimization Of Loading-and-Addition Ball In The Duplex Inlet & Outlet Coal Mill

Double-in and double-out coal ball(DIDO-CM)mill are widely used in our country' thermal power industry rely on its many advantages.Its operation' good or bad will directly affect the safety of boiler and economy and stability of the whole thermal power unit.At present,the domestic research on DIDO-CM concentrate mainly on the monitoring and control of material level,but the study of modeling and control system of DIDO-CM pulverizing system is still at an early stage.It is difficult to find a more accurate mathematical model to analysis the mechanism of the dynamic characteristic of DIDO-CM coal pulverizing system.By using the mechanism modeling method and considering the influence of raw coal moisture and mechanical thermal in energy balance,a three-input three-output dynamic mathematical model of the DIDO-CM is set up based on mass and energy conservation.It is respectively analyzed the influence of DIDO-CM material level,outlet temperature,and t output of the coal mill when the hot air quantity,cold air quantity and coal feed rate has a change.It is simulated with Matlab/Simulink on a MGS-4060-A type DIDO-CM in a 600 MW unit as an example and get the output curves under step input.The results are in conformity with actual.The model could provide an mathematical material and operation optimization ofFrom the angle of the steel ball movement theory,based on steel ball three-phase hybrid motion model to calculate the normal speed expression of steel ball in the fall back hit points.Analyzing wear mechanism of steel ball,the wear amount in line with the principle of superposition.The ball wear amount is equal to the total wear of impact wear components,grinding strip wear and corrosion wear.According to the characteristics of the DIDO-CM grinding mill from the ore grinding environment,corrosion and wear components is very small relative to other two.So it can be ignored.The pulverized coal under the condition of steel ball wear mode is mainly mechanical wear and chemical wear.On the basis of the wear law,a prediction mathematical model for the law of ball wear is established between the ball wear and working condition of coal grinding and the main method of calculating the unknown coefficient k1 and k2 is given.By using the model,the variation law of steel ball diameter under different coal mill diameter,transfer rate,filling rate of ball can be simulated and predicted.It has practical significance to the stability ball rate,reducing the steel consumption and power consumption.Ball installation,ball diameter ratio and the actual power plant to determine the best method of ball quantity of DIDO-CM are introduced.As the steel ball is wearing,the barrel grading of steel ball inevitably change.Then is the problem of ball adding to maintain the original load of steel ball and ball charge particle size characteristics.According to the mathematical wear model of steel ball,the granularity characteristic equation model of steel ball wear is analyzed and deduced.It is applied to the reasonable ball adding and the grinding of the simple "construction law" adding ball is introduced to DIDO-CM.It provides a theoretical basis to the formulation of reasonable adding ball solution.