Research On Intelligent Combustion Method For 600 MW Wall Type Tangentially Fired Boiler Based On CO/O₂ Dual Parameters

After the application of low-NO_x combustion technology for coal-fired unit boilers,there is a contradiction that needs to be reconciled between the high-temperature,high-oxygen conditions required for efficient boiler combustion and the low-temperature,low-oxygen conditions required for low nitrogen emissions.How to control boiler NO_xemissions,at the same time,ensuring the efficient combustion of boilers has become an urgent problem for coal-fired power plants.As a key component of the pulverized coal combustion process,CO can effectively reflect the combustion characteristics of the boiler and has a strong correlation with the NO_x generation during the combustion process.Therefore,CO can be an important parameter reflecting the combustion state of the boiler and the NO_x generation characteristics.This paper takes a domestic 600 MW wall-type tangential low-nitrogen combustion boiler as the research object,establishes a boiler CO online monitoring system,and develops a boiler intelligent combustion model and method based on CO/O₂ dual parameters,in order to coordinately solve the high efficiency and low nitrogen emissions of coal-fired boilers The contradiction between provides an effective new way.First,a CO online monitoring device was arranged for the typical furnace area and tail flue of a 600 MW wall-type tangentially fired boiler,and a CO full-process online monitoring system was established.Meanwhile,the boiler performance test and research were carried out to obtain the typical boiler load and operating parameters and boiler combustion characteristics under working conditions.The test results show that under the low-NO_x combustion condition,the CO emission concentration in the flue gas is significantly increased.Under the test conditions,the chemical incomplete heat loss caused by CO in the boiler flue gas can reach about 0.3%,which has a significant impact on the boiler efficiency;at the same time,boiler CO generation characteristics and various key heat losses of boiler combustion also show obvious correlation.On the other hand,under different load conditions during the test,the NO_x emission from the boiler furnace decreases with the increase of the flue gas CO concentration,indicating that the boiler CO generation characteristics and NO_x generation characteristics also have a significant correlation.In the low-NO_x combustion mode of the boiler,CO can be used as an important parameter reflecting the combustion state of the boiler and the characteristics of NO_xgeneration.Then,full-scale geometric modeling and meshing were carried out for the 600 MW boiler,and the numerical simulation study of the boiler combustion process under typical load and working conditions was carried out.Further comparison of numerical simulation results and test results under different loads and typical operating conditions of boilers of600 MW,450 MW and 300 MW showed that the characteristics of CO generation during boiler combustion and the temporal and spatial distribution characteristics and changes of combustion process temperature and NO_x concentration are obvious.Based on the established CO online monitoring system,the CO/O₂ dual parameters can be combined to effectively reflect the combustion status of the boiler and the changing law of NO_x emission characteristics.Next,combined with the big data mining and analysis of boiler historical operation,based on the analysis of boiler fuel cost and denitrification cost,a comprehensive economic index of boiler combustion is proposed,and a correlation model between the comprehensive economic index of boiler combustion and the dual parameters of boiler CO/O₂ is established.The results of the study show that the comprehensive economic index of combustion of the 600 MW boiler studied shows a trend of first decreasing and then increasing with the increase of flue gas CO concentration,indicating that by reasonably regulating the CO/O₂ generation characteristics of the boiler combustion process,the boiler fuel cost and denitrification cost comprehensive optimization can be achieved,so as to ensure efficient and low-nitrogen combustion of the boiler.Finally,a boiler intelligent combustion model and software/hardware system based on CO/O₂ dual parameters were developed,and the application and verification comparative analysis were carried out on a 600 MW wall-type tangentially fired boiler.The research results show that the CO/O₂ dual-parameter boiler intelligent combustion system based on the establishment can reasonably optimize the boiler combustion and NO_x emission.The boiler efficiency and furnace NO_x emission change trend and system prediction before and after combustion adjustment according to the system guidance are basically the same;under different load and working conditions,the boiler efficiency is increased by about0.22%～0.37%,and the overall economic cost of boiler fuel and denitrification is optimized.The established boiler intelligent combustion system can effectively balance the contradiction between the boiler’s high-efficiency combustion and low nitrogen emissions,providing a basis for the development of intelligent combustion technology for coal-fired power plants.