Nitric Oxide Formation During Pulverized Coal Combustion

Abstract

Data on the overall conversion of coal-nitrogen to NO_x were obtained at 1250 K and 1750 K for a residence time of one second. The conversion of coal-nitrogen to NO_x decreased monotonically with increasing fuel/oxygen equivalence ratio and decreased slightly with increasing temperature. Oxidation experiments were also carried out on char in order to separate the contribution to NO_x emissions of the char from that of the volatiles. The char used was prepared by the pyrolysis of coal at a temperature and residence time corresponding to those of oxidation experiments. The conversion to NO_x of char-nitrogen was lower than the corresponding value for coal-nitrogen. It was found that volatilized nitrogen compounds accounted for a major fraction of NO_x produced from coal-nitrogen, especially at high temperatures and low fuel/oxygen equivalence ratios.