NOX AND CO EMISSIONS FROM A PULSE COMBUSTOR OPERATING IN A LEAN PREMIXED MODE

Control over the combustion fluid dynamics was used to minimize the emission of NOx and CO. The combustion kinetics were controlled by operating the combustor premixed and were varied by modifying the equivalence ratio over the lean stability envelope. A wide dynamic range in fluid dynamic mixing characteristics was also investigated by modifying the degree of macroscopic mixing and microscopic mixing. The residence time at high temperature was controlled by modifying the frequency of the periodic reacting flow in a pulse combustor. It was found that controlling the flame temperature, chemical kinetics, and residence time at high temperature was best accomplished by controlling the equivalence ratio and the degree of macroscopic mixing rather than controlling the microscopic mixing over the dynamic range obtainable by the techniques used in this study. Emission levels below 5.0 ppm NOx, with corresponding levels of 5.0 ppm CO (corrected to 3% O-2), were achieved in a pulse combustor operating in a lean premixed mode, without the use of any postcombustion cleanup technologies. Both NOx and CO emissions were invariant to changes in the power input.