Optimal Operation And Mechanism Modeling Simulation Of Direct-fired System Pulverize

The energy consumption problem of thermal power plant is the main factor affecting the benefit of China's power industry.The average power supply coal consumption and SO₂ emissions of coal-fired power plants in China are higher than the world level.Coal mill is the main equipment of coal pulverizing system,and its operation state directly affects the combustion status of the boiler and the safe,stable and economical operation of the whole unit.Therefore,the mechanism modeling and simulation of the direct fired pulverizing system are carried out,and the operation optimization is carried out Of great significance for the development of key energy group of the world.To realize rapid and effective evaluation and control on MPS medium speed mill,a mathematical model was built comprehensive with grinding,drying,separation and circulation process.MPS medium speed mill was divided into five parts as bowl zone,grinding zone,separation,classifier and tank,and coal quality balance,heat balance and moisture balance formulas were established.MATLAB was used to calculate and simulate the dynamic process of MPS coal mill.Results show that the simulation curves of capacity,temperature of outer and temperature of mill tank are met with practical operation under a disturbance of temperature of primary wind,quality of primary wind and feed at a given condition.The simulation curves of pulverized coal-fineness are met with practical operation under different quality of primary air and speed of separation.The model can predict the variation of operation parameters of coal mill effectively.One double-inlet and double outlet ball mills,the initial balls loading is over capacity,the scheme for supplement balls is unreasonable,the abrasion of steel balls is excess,and the electricity consumption for grinding is huge.To solve these problems,a new method that can accurately calculate the initial balls loading,the period and quantity of adding balls for the double-int and double-outlet ball mill is presented,on the basis of building up the models for steal balls'motion in the barrel and abrasion synthesizing with impact,grinding,friction and impact fatigue.Taking coal mill E in a power plant as the example,this method was applied to ascertain the period and quantity of adding balls after less ball transformation,in consideration of variation of power,maximum capacity quantity and fitness of coal powder caused by variation of steel ball loading.The steel ball abrasion steady characteristics matrix was deduced by variation of distribution of steel balls size,and it was employed to calculate the compensatory quantity of each grade of balls.Compared with the abrasion of steel balls and consumption of power of coal mill B which uses the conventional initial loading balls and adding balls method?706.82 yuan/h?,that of the coal mill E applying the new method is 426.57 yuan/h,indicating the new method has remarkable economic benefit.Raising the outlet temperature of coal mill can improve boiler operation efficiency.A prediction model of ignition temperature TC,a prediction model of infrared spectrum temperature t_hw,and a prediction model of thermo gravimetry ignition temperature t_rw are established,and a method for determining the safe temperature value of coal mill outlet is proposed.Results show that in the test of HP coal mill under the load of 100%?75%and 50%in a power station,when the outlet temperature of coal mil increases from 80.1?to 85.6??from 79.8?to 85.4??from 79.5?to 86.0?,the operation efficiency of boiler,improves,realizing the purpose of energy saving and consumption reducing.