The report gives results of testing 19 coal, oil, and gas-fired industrial boilers to determine their normal emissions and the effectiveness of combustion modifications in reducing NO(x) emissions without increasing the emission of particulates and other pollutants. Combustion modifications investigated were: reducing excess air, recirculating flue gas, staging combustion air, adjusting burner swirl registers, reducing combustion air temperature, tuning the burner, changing atomization pressure, and changing oil temperature. Emissions were found to be not significantly dependent on boiler size, but very dependent on the fuel. Generally, the normal NO(x) emissions were below EPA Standards for New Stationary Sources. Particulate emissions from oil and gas were below 43 ng/J (0.1 lb/million Btu); from coal, they are above by a factor of 5. NO(x) reductions of as much as 50% were obtained with several combustion modifications. In most instances the boiler heat-loss efficiency was not degraded. Although particulate emissions usually increased, the increase could be limited by fine-tuning the boiler. There was no significant effect on any other pollutant emission.

Prepared by KVB Engineering, Inc., Tustin, Calif., under contract no. 68-02-1074, ROAP no. 21BCC-046, program element no. 1AB014. Tables. Includes appendix. "EPA/600-2-76-086a." "April 1976." Includes bibliographical references (pages 235-236).