Influence of solid fuels parameters on NOx emissions in combustion

Emission of NOx was measured during pulverised coal combustion of twenty-five power station coals. The coals cover the range from anthracite to lignite. The individual separated effects of coal properties on NOx emission and conversion ratio from fuel N to exhaust NOx were clarified through experiments in an electrically heated, temperature-controlled furnace under almost identical combustion conditions. The conversion rate of the fuel nitrogen to NOx based on NOmax, the limiting value if all fuel nitrogen were converted. Fuel NOx emission generally increased with increasing fuel nitrogen content and coal rank. The nitrogen content does therefore not give much of an indication of the NOx concentration to be expected. NOx emissions decrease with increasing or decreasing volatile mater from 30%. The conversion rate declines with nitrogen content and increases with volatile matter content. The highest conversion rates were established with low rank coals and lowest with anthracite.