Influences of ammonia co-firing on the NO generation characteristics of pulverized coal during different combustion stages

Abstract

As an ideal carbon-free fuel, ammonia is a feasible choice to replace part of coal fuel to reduce carbon emissions from coal-fired power generation. This work used a constant temperature fixed bed experimental platform to study the effects of ammonia mixing on NO formation characteristics of pulverized coal. It was found that the peak time of NO precipitation decreases with the temperature increasing in ammonia-coal coupled combustion, and the increase of ammonia blending ratio promotes the NO formation. In the ammonia-coupled coal char combustion, NO production increases with the increase of ammonia co-firing ratio under different temperature conditions. Compared with coupled combustion, separation combustion can effectively reduced the NO formation, which was not conducive to the conversion of fuel-N to NO, and the ammonia mixing ratio and temperature have a significant impact on the range of NO generation reduction in separation combustion. At the temperature of 1300 °C and 1400 °C, the nitrogen conversion ratio of 0%, 4% and 20% ammonia co-firing ration was reduced by 19.64%, 9.23%, 0.22% and 13.35%, 1.86% and 0.15%, respectively, compared with that of coupled combustion. The results can provide theoretical support for the development of low nitrogen combustion technology of ammonia-coal co-combustion.