Effects of fuel characteristics on the NO reduction during the reburning with coals

This paper studies the effects of different kinds of pulverized coals and their chars on the reduction of NO in the rich-fuel reburning zone using a bench-scale flow reactor. Fuels chosen for the reburning in the experiment are the Chinese Xiaolongtan lignite, Fulaerki lignite and Datong bituminous coal and their chars. The Datong bituminous coal chars added with different catalysts are also used. Experiments were conducted under conditions with initial NO concentration of 1000 ppm and reaction-zone temperatures of 900 and 1100 degreesC. The present experiments verify the results reported in available references, namely the NO reduction capacities of the lignites and lignite chars are appreciably stronger than those of the bituminous coals and bituminous coal chars. Experimental results also show that in the reburning with a coal as the fuel, heterogeneous mechanisms make a significant contribution to the reduction of NO. The specific surface area of char particles and the content of metal oxides in the char are all important factors, which affect appreciably the NO reduction. (C) 2002 Elsevier Science B.V. All rights reserved.