Development And Application Of Self-correction System For Boiler Flue Gas Temperature Deviation Based On Intelligent Control

Due to the inherent residual rotation of the tangentially fired boiler,there are serious problems of flue gas temperature and steam temperature deviation between two sides of the furnace outlet and horizontal flue.This brings great difficulties to the steam parameter control of the boiler,which is not conducive to the control of steam temperature,and also affects the safety of the superheater tube wall and the operation of the steam turbine.In order to solve the problem of flue gas temperature(steam temperature)deviation and find the means and methods to alleviate the flue gas temperature(steam temperature)deviation,this paper takes a 660 MW boiler in a power plant as the research object,and conducts an in-depth analysis of the combustion system of a tangentially fired boiler to find the causes of the deviation of the flue gas temperature(steam temperature).Combining the results of on-site combustion adjustment tests and the operator’s operating experience,we took an automatic control closed-loop control method,and finally realized the real-time dynamic flue gas temperature(steam temperature)automatic correction of the tangentially fired boiler.Based on the analysis of the historical operating data of a tangentially fired boiler,this paper introduces the total heat absorption deviation indicator between the two sides of the superheater to accurately and quantitatively characterize the deviation of the flue gas temperature(steam temperature)between the two sides of the boiler.Analyzing the correlation between many boiler operating factors and the deviation of boiler flue gas temperature(steam temperature),we chose the door opening degree of SOFA air among many influencing factors as the means to correct the deviation of the flue gas temperature(steam temperature).For the SOFA damper opening,this paper analyzes the combustion adjustment test data at multiple load points(4 load points,30 working conditions)on site,and concludes that the deviation of flue gas temperature(steam temperature)between two sides of the boiler can be effectively corrected and adjusted through cooperative control of the upper three-layer SOFA damper on the boiler.Taking the SOFA air volume of the boiler as the manipulated variable,this paper applies the neural network control method and the model predictive control method to the correction control system for deviation of flue gas temperature(steam temperature)between two sides of the boiler,and compares the effects of two control strategies through simulation.The simulation results show that the two control strategies both can reduce the deviation of the flue gas temperature(steam temperature)between the left and right sides of the boiler,but the model predictive control strategy has a better control effect.In the actual application of the model predictive control strategy to realize the real-time dynamic flue gas temperature(steam temperature)automatic correction of the boiler,we analyzed the deviation between two sides of the total heat absorption of the superheater,the deviation of the desuperheating water flow between two sides of the superheater,and the temperature difference between the two sides of the outlet steam temperature of the high-temperature superheater.The analysis results further confirmed the effectiveness and practicability of the model predictive control algorithm in the self-correcting control of the flue gas temperature(steam temperature)of the boiler combustion system.