Impact of the air staging on the performance of a pulverized coal fired furnace

The aim of this work is to evaluate the impact of the air staging oil the overall performance of a large-scale laboratory furnace fired by all industry-type pulverized coal swirl burner. Data have been obtained for pollutant emissions and particle burnout for a wide range of the furnace operating conditions. The influence of the axial position of the staged air injector, of the primary zone stoichiometric ratio of the coal type, and of the configuration of the staged air injector oil pollutant emissions and particle burnout are quantified oil the basis of these results. The main conclusions are as follows: (i) NOx emissions decrease as the distance between the staged air injector and the burner exit increases however, if the distance exceeds a given value, CO emissions increase significantly; (d) in general, a reduction In lambda(pZ) causes a decrease in both NOx emissions and particle burnout and all increase in CO emissions. Moreover. this results Suggest that the benefits in terms of reduction of NOx emissions obtained with values of lambda(pz) < 0.9 can be considerably attenuated by its deleterious effect on the overall combustion efficiency; (iii) the type of coal call affect significantly the effectiveness of this NOx control method; it is not possible, however. to establish definitive correlations between the reduction in NOx emissions and the main coal properties; and (iv) the configuration of the staged air injector has little impact on NOx emissions, because the air staging effectiveness is a strong function of lambda(pz), but it is a key Feature in establishing the overall combustion efficiency for lambda(pz) < 1. (c) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.