Gas turbine catalytic combustor with preburner and low no.sub.x emissions

Abstract

During low-load operating conditions, preburner combustion products are supplied with a chemical reactant to reduce NO.sub.x. The preburner products of combustion are mixed with a hydrocarbon fuel in the presence of a combustion catalyst to ignite and initiate a catalytic combustion reaction. The preburner is then shut down. The fuel/air mixture supplied the catalytic reactor bed during the mid-load operating range of the turbine is sufficiently lean to produce a combustion reaction temperature too low to produce thermal NO.sub.x. Thus, at low-load conditions, preburner combustion occurs with NO.sub.x reduction by chemical reactant, while the catalytic combustion occurs at mid-range operating conditions at temperatures too low to produce NO.sub.x. For high-load operating conditions, the catalytic combustion occurs as previously described and additional lean fuel/air mixture is supplied the reaction zone whereby thermal NO.sub.x is likewise avoided.