Devolatilization and oxidation of coal nitrogen

Early evolution of coal nitrogen in opposed flow combustion configurations

“…It is, futhermore, noted that the tar products undergo secondary pyrolysis reactions which are rapid for the bituminous and slow for the lignites. Data for the bituminous coal under oxidizing conditions clearly show that secondary pyrolysis is extremely rapid for smaller particle and lead to large quantities of NO x ' Present results fully complement the work of Pohl and Sarofim (1977) and Song et al (1982) who reported that lower rank coals yield less volatile nitrogen than bituminous coals during the initial transients of rapid heating conditions. This phenomena, hence, leads to larger quantities of nitrogenous species, especially NO, for fine bituminous particles.…”

“…The experimental concentrations of Total XN species and the corresponding values predicted using the rate constants from the present study, Pohl and Sarofim (1977) and Solomon and Colket (1978) Mereb (1990) studied the fate of nitrogenous species in a laboratory size down fired plug flow pulverized coal combustor. Details of furnace are described elsewhere (Bose, Dannecker and Wendt, 1988;Mereb, 1990).…”

“…Harding et al (1982) correlated the data for ten coals from different studies and determined that rate of evolution of nitrogen and rate of conversion of coal were approximately the same. Pohl and Sarofim (1977) showed that nitrogen evolution paralleled the evolution of total volatiles. However, they did not observe the release of any nitrogen until about fifteen percent of devolatilization had taken place.…”

“…They observed that conversion of volatile nitrogen to NO x could be readily controlled by changing the mixing characteristics of the system, while conversion of char nitrogen to NO x was independent of mixing effects. Pohl and Sarofim (1977) reported that under fuel-lean conditions, at a furnace temperature of 1500 K, up to eighty percent of NO x was formed by oxidation of volatile nitrogen. They observed that increasing equivalence ratio (defined as (fuel/oxidant )actuar/ (fuel/oxidant )theoreticaz) reduces the conversion efficiency of volatile nitrogen to NO x .…”

Nitrogen Oxides Emission Control Options for Coal-Fired Electric Utility Boilers

“…16 In pulverized coal combustion in a utility boiler, fuel NO x may typically contribute up to 80% of the NO x emissions. 14 Formation of fuel NO x depends on the nitrogen content in the fuel and the amount of oxygen available to react with the nitrogen during coal devolatilization in the early stages of combustion.…”