Release of fuel-nitrogen during the gasification of Shenmu coal in O 2

Abstract

Formation of NH 3, HCN, NO and NO 2 from the gasification of a Chinese coal (Shenmu) in a fluidised-bed/fixed-bed reactor in 4.1% O 2 in argon was investigated. The presence of O 2 even at 673 or 773 K could lead to the gradual gasification of char to form HCN and NH 3. The yields of NH 3 and HCN showed maxima at about 773 K, amounting to 40% of coal-N. In the presence of O 2, the H radicals required for the formation of NH 3 and HCN may be generated from the reactions in the gas phase and within the solid particles. The yields of NO x increased from 773 to 973 K. A non-negligible proportion (∼5%) of coal-N was converted into NO 2 at 773 K through homogeneous and heterogeneous reactions. The yield of NO 2 diminished with increasing temperature. At 1173 K, the reactions between char-N and H 2O (or O/H-containing radicals) formed from the oxidation of char and volatiles led to the formation of NH 3 but not HCN. This route of NH 3 formation is believed to be an important pathway for the formation of NH 3 in an air-blown gasifier.