Design And Application Of SCR Denitration Control System For Coal-fired Units

With the increase in global electricity demand,coal-fired power generation will continue to occupy the first place in the global total power generation.Nitrogen oxides emitted by coal-fired units is one of the main sources of atmospheric pollutants and have a serious impact on the decline in air quality.Therefore,most coal-fired units are currently equipped with an SCR denitration system to remove nitrogen oxides.SCR denitration system is a new addition system of coal-fired units in recent years.Moreover,the control of SCR denitration system is extremely difficult,so there is no ideal automatic control scheme.In this paper,based on the characteristics of SCR denitration system,a composite control strategy of feedforward and feedback of SCR denitration system is proposed,and applied it into the actual system to verify its effectiveness.The main research contents are as follows:(1)Introduced the basic principle and basic characteristics of SCR denitration system.Summarize and compare the characteristics of three different control strategies: SCR denitration system fixed molar ratio control,export NOx fixed value control and compound control.(2)According to the characteristics of large delay and large inertia of SCR denitration system,the control effects of various control schemes on large delay and large inertia system are compared.The model predictive control is used as the closed-loop control method of SCR denitrification composite control strategy.(3)The conventional SCR denitrification fixed molar ratio control strategy was analyzed.According to the problem of the system in practice,the SCR denitrification control strategy feedforward control method was designed with reference to the idea of fixed molar ratio control.(4)The artificial intelligence model based on historical data was used to establish the SCR denitration system simulation platform.Analyzed the actual operation,build a composite control strategy control system and determine its parameters.The effect of the control strategy was tested by simulation.(5)The design of the control logic SAMA diagram of the SCR denitrification composite control strategy is completed.The control strategy parameters determined by the simulation are used to verify the control effect in the actual system,which proves that the proposed control strategy is feasible and effective.