Distribution of HCN, NH3, NO and N2 in an entrained flow gasifier

Abstract

A laboratory gasifier with the opposed multi-burners (OMB) was used to investigate the formation of nitrogen compounds during coal water slurry (CWS) gasification. Various axial and radial concentrations of HCN, NH 3 , NO and N 2 (nitrogen compounds) in the gasifier were measured. The concentrations of HCN, NH 3 and NO (nitrogen pollutants) were maximal at the nozzle plane and decreased along the axial distances. Moreover, the ordering of nitrogen compounds in exit was N 2 > HCN > NH 3 > NO. An increase in O 2 /C ratio tends to favour the formation of N 2 . Flow field distribution resulted in the radial concentrations uniform at the exit and low near the side-wall at other axial positions. The results showed the majority of nitrogen pollutants formed from coal volatile nitrogen during the rapid devolatilization. HCN and NH 3 formed mainly from devolatilization at the nozzle plane but were not thoroughly converted from the reduction of NO. H 2 O in CWS played a vital role in converting coal-N into NH 3 and HCN by providing H.