| In coking processes,cove oven could generate a large amount of environmental harmful pollutants,one kind of which is nitrogen oxide(NO_x).NO_x can not only form the acid rain and photochemical smog,but also damage the ozone layer,therefore,technology of reducing or controlling the emission of NO_x have been particularly attractive.Only through our depth understanding of the law of the migration of the coke oven heating system as well as the relationships of working conditions between its generation and heating,can it contribute to the reduction and control of the nitrogen oxide emissions.In this paper,a detailed study was done in order to find the migration law of the nitrogen oxide emissions of the heating system in the coke oven.Three kinds of furnaces were chosen as the sample objects,they are respectively 6m coke oven,7m coke oven and 7.63m coke oven.The sampling points are in the side of sub-flue flap machine coke and in the rear side of total flue flap,then,analysis these samples with KANE QUINTOX portable flue gas analyzer.Emphasis was put on the relations between the nitrogen oxide exhausts producing in coking processes and coke oven furnace type,temperature of machine coke,heating methods,heating gases,coal quality for coking.The formation mechanism and influence factors of Thermal NO_x in the process of coke oven combustion was investigated,which focuses on the WISO's 6m,7m,and 7.63m coke oven.Results showed that the emissions of nitrogen oxides about coke oven had a direct relationship with the furnace,excess air ratio and flue temperature.The average NO_x emission caused by 7m and 7.63m coke oven was under 150ppm,while the 6m coke oven was above 300ppm.The amount of nitrogen oxides in the exhaust gas about 6m coke oven was apparently higher than 7m and 7.63m coke oven,because both of the 7m and 7.63m coke oven are using segmented heating,which can control thermal NO_x producing in the process of heating and reduce the NO_x in the flue gas. |
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