The Key Issue Study Of Reduction Of Nox Emissions In Furnace Air Stageing Combustion

Too many utility boilers NOx emissions seriously exceed the emission control regulations established by our country. According to the situation of our country, among all the measures used to control the NOx emissions of coal-fired boilers, the combustion modification measures, especially low NOx burner and furnace air staging measures are the lowest economic and operating costs. Deep furnace air staging could achieve NOx reduction about 60-70% from utility boilers when firing bituminous coals, which could satisfy regulation. Though effective, when the deep air staging measures are used for some coal, the unburned carbon in fly ash and reduction corrosion increase. In order to eliminate the negative impact, the ultimate way is coal fineness and char reduction NOx. In this article, the experimental study is carried out to investigate the combustion influencing factors on the ShenHua bituminous and Yangquan anthracite coals'NOx emissions and burnout in air staging.The coal combustion characters are investigated with one dimensional multipath air inlet furnce. Research the particle size, fineness of pulverized coal, primary air ratio, staged port location (reduction zone and burnout zone residence time referred) and flow rate of SOFA impact on NOx emissions. Different fineness of pulverized coal experimental data could be applied to utility boiler. Research unburning carbon in flying ash in deep air staging, and make it possible to identify the advantage of staging combustion by the oxygen concentration in flue gas.The NO reduction on the char surface was investigated with one dimensional drop furnace. Research the oxygen concentration in reduction zone to enhance the react of NO on the surface of char, found it's beneficial for burnout at the same time. Research the oxygen, carbon dioxide and particle size effect on the NO reduction.According to the fineness experimental and combustion modification test data, set one power plant boiler as an example, investigate the fineness of pulverized coal influence on electicity consume of mill, loss of ignition, and the NOx tax and cost, analysis the economic of different fineness to find the lowest cost one in various air staged combustion, found the new way to identify the economic of pulverized coal fineness.