Combustion modification of expanded coal adaptability in ultra-small section circle-fired boiler
Ultra-small section circle lean coal boiler has problems such as serious slagging and high temperature corrosion.In order to adapt to the current coal market diversification and boiler flexibility operation and other needs,it is urgent to improve its adaptability to complex coal blending.Taking the 300 MW ultra-small section of a power plant as the research object,the coal adaptive combus-tion modification was carried out.Firstly,CFD numerical simulation was used to evaluate the combustion problems of the original combus-tion system of the boiler when mixed with bituminous coal,then the modification scheme of the combustion system was put forward accord-ingly:by increasing the burner distance to reduce the heat load of the burner area,reducing the imaginary circle to solve the flame brush wall,increasing the burn out air rate to achieve deep air classification and other measures,the coal type adaptability of the boiler could be expanded.Then CFD numerical simulation was used to determine the best performance parameters of the combustion modification scheme,and predict the combustion state of the boiler under 67%and 100%low ash bituminous coal after combustion modification.The effective-ness of the combustion modification was verified through the engineering test.The results show that the 300 MW ultra-small section circle-fired boiler can be mixed with 20%bituminous coal to adapt to burn 67%-100%low ash melting point bituminous coal,so the adaptability of coal species can be effectively enhanced.According to the official assessment and test,the efficiency of the boiler in the designed coal condition is improved by 2.25%,NOx emission rate is reduced by 40%-48%,and there is no obvious slagging and high tem-perature corrosion problems in the furnace.The combustion modification scheme provides guidance for the adaptability of bituminous coal.