The report gives results of a field study to assess the applicability of combustion modification techniques to control NOx and other pollutant emissions from utility boilers and gas turbines without causing deleterious side effects. Comprehensive, statistically designed tests were used to evaluate the effect of combustion modifications. The most extensively studied combustion modification for utility boiler applications was staged firing at low excess air, which can reduce NOx emissions by up to about 50%, based on the results of short term tests. With emphasis on NOx emission control for coal-fired utility boilers, special attention was paid to the determination of potentially adverse side effects: increased combustible emissions, unwanted changes in particulate mass loading and size distribution, reduced boiler efficiency, increased furnace slagging and tube wall corrosion, and flame problems. Short term tests indicate that staged combustion may be applied to coal-fired utility boilers. The extent of furnace tube wall corrosion and slagging could not be determined conclusively, based on the results of 300-hour corrosion probing runs under low NOx and baseline operating conditions. For this reason, a long term furnace tube wall corrosion test of at least 6 months duration was initiated on a 500 MWe front-wall-fired boiler at Gulf Power Company's Crist Station.

Prepared for Fossil Fuel Power Plants Dept., Electric Power Research Institute, and Office of Research and Development, U.S. Environmental Protection Agency, under contract no. 68-02-1415, EPA Program element no. EHE624A, EPRI project no. 200. Issued Mar. 1978. Includes bibliographical references.