Effect of Trace Combustion Species on SNCR Performance

The results of laboratory tests to evaluate the effect of trace combustion species on N2O production for the selective non-catalytic reduction NOx reduction process (SNCR) are presented. The tests were conducted under controlled conditions in a 200,000 Btu/hr laboratory pilot test combustion facility. Parameters investigated during the tests were: type of reducing agent (urea and ammonia); concentration of reducing agent relative to initial NOx concentration (N/NO - 0,1,2); temperature; carbon monoxide (CO) level (0-2000 ppm); and initial NOx level of 125 ppm. Results are presented which show the effect of these parameters on the NOx removal temperature "window", final CO emissions, "leak" NH3 emissions, and resulting N2O emissions. Several phenomenon not previously reported are described. Of particular interest is the effect of the initial CO level on N2O production for urea and ammonia. N2O levels are found to be significantly different for these two reagents. The implications of these results for practical combustion systems are discussed.