Research On Combustion Optimization Of 600MW Front And Back Opposed Firing Boilers Based On CO-online Monitoring

There is a strong contradiction between the high-efficiency combustion of coal-fired power station boilers and low NO_x emissions.It is of great engineering significance to optimize the combustion process of boilers with high efficiency and low NO_x.As a product of combustion reaction,CO has a certain relationship with the excess air burned by the boiler,which can effectively reflect the overall combustion status of the boiler.At the same time,there is also a coupling relationship between CO and NO_x generation,so it is a good indicator that can be used to guide boiler combustion adjustment.In this study,600 MW front and back opposed firing boiler was taken as the research object,and a CO online detection system was installed in the rear flue of the boiler;At the same time,an experimental study on boiler combustion adjustment performance was carried out under different load and air distribution conditions,and the operational performance parameters and tail CO online detection data under different conditions of the boiler were obtained.The analysis shows that at 100%,75% and 50% load,the exhaust heat loss of flue gas decreases with the increase of CO concentration.As the CO concentration increases,the boiler efficiency increases first and then decreases.The NO_x emission concentration of the boiler gradually decreases with the increase of the CO concentration in the tail.The fuel cost and denitration cost of the target boiler were analyzed,and a comprehensive index model of combustion optimization coupling boiler efficiency and NO_x generation was established.The research shows that the fuel cost under different load and working conditions of the boiler decreases first and then increases with the increase of CO concentration in the tail;the denitration cost decreases with the increase of CO concentration in the tail,and the final comprehensive index first decreases with the increase of CO concentration in the tail After the increase,there is an optimized value of the comprehensive index.Based on the correlation between the tail CO emission characteristics and the comprehensive indicators,using the batch data of the boilers in the power plant DCS system and the CO online detection system at different time periods and different working conditions,the boiler tail CO emissions and comprehensive indicators under different working conditions were established Correlation model,and developed boiler combustion optimization software and system based on tail CO online detection.At the end of the research process,the boiler combustion optimization system based on tail CO online detection was implemented and operated on the target 600 MW boiler,and a performance adjustment verification experiment of the boiler combustion state was carried out.The experimental results were consistent with the prediction values given by the combustion optimization system,which verifies the accuracy and stability of the system,and provides the theoretical and engineering basis for the combustion optimization adjustment research of this furnace type and related furnace types.