Process for reducing NO emissions

Claim 1

In a non-catalytic combustion process wherein a reducing gas comprising ammonia, either alone or in combination with one or more additional reducing gases, is injected into a flowing combustion effluent containing NO and oxygen when at least a portion of said combustion effluent is in a reduction zone at a temperature within the range of about 850° C. to about 1100° C. to reduce the NO concentration therein, the improvement which comprises placing a metallic material selected from the group consisting of heat resistant iron-based alloys, nickel-based alloys, cobalt-based alloys, and oxide dispersion strengthened alloys substantially at the end of the reduction zone, said metallic material having a surface area greater than about 0.5×10 -2 m 2 per Nm 3 /H of the combustion gas effluent flow within a gas residence time zone of less than one second from the ammonia source, thereby substantially reducing ammonia breakthrough without substantially producing additional amounts of NO.