Comparison of nitrogen oxide emissions from boilers for a wide range of coal qualities

This paper presents the results of experimental researches on nitrogen oxid e emissions from coal-fired boilers. Two Chinese lean coals have been fired in two full scale boilers (1025 t.h(-1)) and in a pilot scale test furnace (Drop-Tube Furnace) to study the influence of nitrogen content in coal on nitrogen oxide emission. The nitrogen oxide emission was found to correlate well with the fuel nitrogen content. The test results of the drop-tube fur nace and the single burner furnace with three Chinese coals show that the s taged combustion can greatly reduce the nitrogen oxide emission. Identical trends in nitrogen oxide emission as a function of the volatile matter of t he coals have been obtained under different combustion conditions. The prin ciple of low nitrogen oxide emissions of the wide range burner (biased comb ustion or internal air staging) and the cases with over fired air port (fur nace air staging) is introduced in this paper. In addition, the influence o f excess oxygen content on nitrogen oxide emission has been tested in the u tility introduced in this paper. In addition the influence of excess oxygen content on ni boilers and test furnaces. (C) 2000 Editions scientifiques e t medicates Elsevier SAS.