NOx formation from several Chinese coals during combustion in packed bed

The formation characteristics of NOx during combustion of four typical Chinese coals have been studied in a packed bed combustor. The studies included the effects of chemical composition of coals and volatile matters, and combustion conditions, i.e. preheating temperatures of combustion gas, on conversion of NO(x)during combustion. In term of the combustion experiments, there is a close relation between coal composition and conversions of NOx. Coals with a higher nitrogen content give a lower F-NOx(o) and coals with a higher volatile content give a lower F-NOx(o). The further devolatilization experiments showed that volatile matters in the coal have an important effect on reducing conversion of coal-nitrogen to NOx. It was interpreted as that the release of volatile matters during combustion caused a fuel-rich circumstance in the vicinity. of coal particles which may restrain the formation of NOx. Preheating temperatures of combustion gas has significant effects on conversions of NOx and there exist a critical preheating temperature. At such temperature, lower F-NOx(o) can be reached.