LAUSR

Abstract In this paper, a fixed-bed reaction furnace system was established to separate the process of volatile combustion and the process of char combustion. The effects of combustion environment temperature, particle size, and recycled-NO concentration on the interaction between volatile-N and char-N and their contributions to fuel-NO were studied in O2/CO2 atmosphere. Three typical coals with different ranks and particle sizes were employed to determine the conversion mechanism of nitrogen from volatile or char combustion. Through comparing the separated and coupled combustion of volatile and char, the impact of different combustion types has also been highlighted. The results show that the release amount of fuel-NO decreases monotonically in O2/CO2 atmosphere and the proportion of volatile-NO to fuel-NO increases with combustion environment temperature increasing. The interaction between volatile-N and char-N in reduction of NO to N2 becomes more significant than redistribution of fuel-N at a high temperature. As particle size increases, the release amount of fuel-NO from the anthracite combustion raises. However, the proportion of volatile-NO to fuel-NO decreased and the variation of NO release amount from the anthracite is more obvious than other coals. Moreover, with the recycled-NO concentration increasing, the release amounts of volatile-NO and fuel-NO decrease substantially.