The report summarizes a 3-year study of the formation and control of nitrogen and sulfur oxides (NOx and SOx) in industrial coal-fired boilers, with emphasis on stoker-fired units. Three major research areas were considered: the evolution and oxidation of fuel nitrogen and sulfur, the retention of SOx by ash and/or solid-chemical sorbents, and the effectiveness of distributed air addition for NOx control. The study also included quantification of the combustion process in a stoker environment and consideration of possible detrimental effects of control technology on boiler operation. Study results indicate that two types of NOx controls appear to be viable: (1) the coal feed could be screened to remove the fines (particles < 0.1 in.), essentially eliminating the high conversion of nitrogen evolved in the suspension zone and resulting in an overall emissions reduction of about 10-40%, depending on the amount normally present in the raw coal; and (2) the primary overfire-air injection port could be moved to above the spreader and the suspension zone and bed region could both be operated substoichiometric, reducing emissions by as much as 50%. Unfortunately, controlling SO2 formation in either a spreader or mass-burning stoker unit appears to be difficult.

Caption title. "February 1984." "EPA-600/7-84-026." Microfiche.