Research On Combustion And Slagging Characteristics Of Coal-fired Boiler

The furnace slagging problem is a common and difficult problem in boiler operation,which affects the safety and economy of boiler operation.Taking a 1000 MW tangentially tower type coal-fired boiler as an example,against serious slagging problem in the burner region,3-D steady numerical simulation on combustion in the boiler was carried out with FLUENT Software.The error between the measured temperature and the numerical simulation results was within the allowable error range,which verified the results of numerical simulation.A model of slagging was set up.The particles whose temperature is more than the softening temperature of coal ash and which impact wall are regarded as slagging particles.The percentage of the slagging pulverized coal particles mass of the total pulverized coal particles mass is as a basis for judging the degree of slagging of the boiler water wall.This paper focused on the influence of pulverized coal particle size,boiler load,the secondary air distribution and the porosity of coal particles on the slagging and fly ash carbon content in the furnace with numerical simulation.The degree and the cause of the slagging were analyzed in detail.It is found,(1)applying generalized regenerative technology,the temperature of primary air and secondary air increase,thereby improving the temperature and the combustion rate of pulverized coal particles,which solves the problem that the slagging of water wall is serious and the fly ash carbon content is high at low boiler load to a larger extent when burning easy slagging coal.(2)Compared with equal air distribution,inverted pagoda air distribution and shrinked-middle air distribution,adopting the positive pagoda air distribution,the slagging of water wall is slight and the fly ash carbon content is low,so the secondary air distribution of the boiler is recommended by positive pagoda air distribution.(3)The higher the initial temperature of pulverized coal particles is,the larger the pulverized coal porosity is,the lower the fly ash carbon content is,and the more difficultly the boiler water wall is slagging.Then,in the case of preventing the deflagration of the nozzle,we should try to improve the temperature of the initial temperature of pulverized coal particles.The results of this paper provide the basis for the operation,design and modification of coal-fired boiler.