Fuelnitrogen transformations in one-dimensional coal-dust flames

Experiments on the distribution of fuel nitrogen in pulverized-coal/O 2/Ar flames stabilized on a flat-flame burner are reported. The gas-phase concentration of HCN, NO, NH 3, and N 2, and the solid-phase nitrogen content were measured as a function of reaction time. A complete inventory of the major nitrogen-containing species is attained for two fuel-rich stoichiometries. Coal-nitrogen release is found to be more complete in the leaner flame. HCN and NO account for most of the gas-phase nitrogen early in the flames, while N 2 predominates later. Particle and gas temperature profiles were obtained with an infrared pyrometer. Early in the flame the particle and gas temperatures do not differ much, but the gas may eventually be as much as several hundred Kelvin hotter than the particles. The experimental results are used to determine overall rate constants for coal-nitrogen devolatilization and for N 2 formation.