Minimizing no.sub.x production in operation of gas turbine combustors

Abstract

A novel method for operating gas turbine combustors while minimizing the formation and discharge of pollutants such as NO.sub.x is described. In one embodiment, the use of more than one catalyst in series is employed to effect fuel oxidation at temperatures below flame temperature, thereby minimizing NO.sub.x formation. In another embodiment, a staged catalytic combustor is employed comprising a two zone combustion chamber involving a noncatalytic zone in which fuel is partially combusted under fuel rich conditions and combustion is completed in the second zone, utilizing catalytic oxidation with excess air to complete the combustion and minimize NO.sub.x formation. Still another embodiment concerns the use of a novel design for the primary combustion zone by which fuel is partially burned with substoichiometric amounts of air and, thereafter, the partially burned primary zone effluent is mixed into the secondary air stream where continued combustion proceeds at a temperature below that needed for NO.sub.x production. The operation of the primary zone under fuel rich conditions minimizes NO.sub.x formation, and the novel primary combustion zone design provides good mixing of the hot, partially burned primary zone effluent into the secondary air stream.