Study On Process Optimization Of Coal-pulverizing Systems And Energy Saving Control

Ball mill pulverizing system is the key equipment in thermal power plantthermodynamic system, due to the national energy conservation policy is put forward inrecent years, accelerates the automation process of various industries, mainly displays inequipment updating and optimization of process control system, and realize themaximization of saving energy and raising economic benefit. This paper in a powerplant unit#2(boiler) intermediate storage pulverizing system as the background, thesystem is currently mainly on the operator according to personal experience, through theinward and outward pressure difference and the outlet temperature of solid materiallevel of value judgment mills (no material level measuring system) which exposure tothe coal quality changes and differences in the levels of operating limits, in the processof actual operation, owing to coal, coal wall, overtemperature and overpressure, powderleakage phenomenon occurs frequently, it serious threat to the boiler safe and stableoperation, and failure to achieve stability and economic operation.Through analysis and research on the pulverizing control system principle, andaccording to the economic performance characteristic which caused by strong coupling,and low material level measurement inaccuracies,proposed the control strategy whichcombined with the level optimization，dynamic matrix predictive control DMC andfuzzy PID control,and using feedforward decoupling control algorithm in view of strongcoupling, realize the decoupling control of outlet temperature and negative pressureunder the level automatic control. First of all,using material level since the optimumalgorithm can mill biggest output real-time search, the system always run in the bestworking point according to the mill sound signal from the field and mill load parameters,ect; Secondly, according to the amount of material level control system inthe best working point, and use feedforward decoupling control algorithm,realize thedecoupling control between outlet temperature and differential pressuresignal;Finally,by DMC dynamic matrix predictive PID control algorithm on system forreal-time modeling,and real-time optimization in order to more accurate system model,and highercontrol precision.Simulation and experimental results show that this project on XinHua DCSapplication development platform, first of all, realize the closed loop automatic controlof the coal pulverizing system, and material level since the implementation of optimalcontrol algorithm can make the system can real-time search the best operating point,andunder the stability situation of working condition,can make the coal mill output pointslooming maximum output, improve the efficiency of milling.Second DMC dynamicmatrix of fuzzy PID control algorithm can make the control system parameterscorrection according to the real-time calculation error,and can adapt to different workingconditions that outlet temperature and inlet negative pressure and the level of stabilitycontrol.Thirdly,through the feedforward decoupling control algorithm to realize thedecoupling of this system between the three strong coupling circuit,improve the systemtracking performance and disturbance resistance, etc. Through the system control andanalysis of economic performance, reduced current consumption significantly about15%, increased pulverizing output about20%, and reduced grinding coal and steelconsumption by more than10%, improved the automation level and the economicperformance of the system,and is widely used to be so in practice.