RELATION BETWEEN THE BEHAVIOR OF COAL NITROGEN SPECIES DURING RAPID PYROLYSIS AND NO(X) FORMATION DURING COMBUSTION

The effect of coal properties on nitrogen devolatilization in coal during the rapid pyrolysis of 20 coals from lignite to semianthracite has been investigated at 853K to 1488K. Almost all the nitrogen in coal (Fuel N) devolatilized as NH3, HCN and N2. Fuel N conversion or distribution of nitrogen compounds was strongly influenced by coal properties and pyrolysis temperature. The conversion of coal nitrogen roughly showed a tendency to increase with decreasing carbon content. Nox emission from various coals was investigated by using a coal combustor of laboratory scale. The relation between the behavior of coal nitrogen species during rapid pyrolysis and NOx formation during combustion was examined. A model incorporating devolatilization of the volatile nitrogen species was proposed to explain the influence of coal composition. On the basis of the proposed model a determining factor correlated with NOx conversion in a turbulent flow furnace was discovered.