Research On The Intelligent Control Of The Circulating Fluidized Bed Boiler Combustion

With the development of industry, the demand of energy sources israpidly increasing in modern society. The boiler is a very importantthermal power equipment. However, the inefficient-combustion boilerwill cause enormous energy waste and the environmental pollution. Theperformance of the boiler combustion control has the direct influence onthe operation of the whole boiler system. The boiler combustion controlsystem is a complex multi-variable, non-linear, time-varying and greathysteretic controlled member. The conventional automatic controlmethod is difficult to obtain ideal control effect. For solving theabove-mentioned problems, the intelligent control strategy is employedin this thesis to effectively control the combustion process for theimprovement of the combustion efficiency of boiler.The mathematical modeling of circulating fluidized bed boilercombustion by least square fitting is introduced followed by thetechnological process and the control standard of the circulatingfluidized bed boiler(CFBB)’s combustion. Because there exists couplingin the combustion system of CFBB, it is decoupled and then thecoupling and decoupled combustion system is simulated for improvingits control quality. The result shows that the coupling phenomenon doesnot exist in the decoupled system, which lays the foundation for the nextcontrol strategic research.The researching purpose is to make an effective control for theboiler’s combustion process by using the intelligent control strategy. Theordinary PID control, fuzzy PID control, fuzzy PID control based on theparticle swarm optimization and fuzzy sliding mode control aresuccessively adopted. These control strategies are simulated in theSimulink and the simulation results are comparatively analyzed, whichshow that the intelligent control realizes better control effect.In the thesis, the prediction model of NO_xemission is built byadopting the method of the least-square support vector machine and theoperating parameter combination of low NO_xemission is found through utilizing particle swarm optimization for optimization of the reducedNO_xemission parameters, which reach the optimization of CFBBC.Based on the previous research, the intelligent control system of theboiler combustion is designed. In the hardware, the chose of S7-300PLC achieves the control of field apparatus and data acquisition. Also,Siemens’s STEP7software design of the fuzzy control program of PLCand Schneider’s Citect software designs of user of monitoring interfaceare used. The design of the CFBBC’s intelligent control is accomplishedby the combination of software and hardware.