Control Strategy Optimization Research On Limestone-gypsum Wet Flue Gas Desulphurization System

With the rapid development of the national economy people's demand for electricity is increasing,and the coal-fired power plant,which is a major power supply,are also increasing,at the same time,the pollution that is discharged by coal-fired power plant also increased accordingly.Facing the increasingly serious environmental problems and implementation of low pollutant emission that is applied for coal-fired power plant by the country,it is imperative to control and reduce the coal-fired power plant emissions.SO₂,as one of the major pollutants emissions from coal-fired power plants,is getting more and more people's attention.The desulfurization technology of limestone-gypsum wet flue gas desulfurization got the favors of many power plants at home and abroad for its mature technology,wide range of sources of desulfurization agent,strong adaptability for coal type,high desulfurization efficiency and other merits.However,limestone-gypsum wet flue gas desulfurization is a complex process,it not only has many factors that will affect the desulfurization efficiency,but also its desulfurization control system have the characteristics of non-linear,time-varying,large delay,large inertia and so on,the traditional PID control cannot balance the problem between the desulfurization efficiency and the operation of desulfurization system economic stability,and the control effect is poor.Therefore,this paper research a thermal power plant's 330 MW unit limestone-gypsum wet flue gas desulphurization control system,and clear the characteristics of the desulfurization process on the basis of analyzing principle of wet flue gas desulfurization and the efficiency that influence desulfurization,and establish the model of wet flue gas desulfurization system that is based on the control of absorption tower's limestone slurry replenishment,and put forward an internal model control strategy,besides,this paper simulate identified of desulfurization system object model,and compare the simulation results with the traditional PID control,the results show that the internal model control has a small overshoot and a shorter adjustment time,and both dynamic and steady-state performance are better than conventional PID control.However,the internal model control has certain requirements for the accuracy of the identification model.Then this paper improve the internal model control system from the perspective of internal model and internal model controller structure,and put forward an internal model control strategy based on fuzzy gain compensation of object model and another fuzzy internal model PID control strategy,after comparing the simulation results with the conventional PID control and internal model control,we can conclude that the two improved internal model controls show some advantages,especially the fuzzy internal model PID control strategy,it not only has better dynamic performance and steady state performance,but also has good model adaptability and anti-interference ability.The three control strategies can provide theoretical guidance for the control strategy of wet flue gas desulfurization system in coal-fired power plant,and they have certain referenced significance.