US 5,850,731 A · Catalytic combustor with lean direct injection of gas fuel for low emissions combustion and methods of operation

Abstract

A combustor for a gas turbine includes a diffusion flame combustion zone, a catalytic combustion zone and a post-catalytic combustion zone. At start-up or low-load levels, fuel and compressor discharge air are supplied to the diffusion flame combustion zone to provide combustion products for the turbine. At mid-range operating conditions, the products of combustion from the diffusion flame combustion zone are mixed with additional hydrocarbon fuel for combustion in the presence of a catalyst in the catalytic combustion zone. Because the fuel/air mixture in the catalytic reactor bed is lean, the combustion reaction temperature is too low to produce thermal NO.sub.x. Under high-load conditions, a lean direct injection of fuel/air is provided in a post-catalytic combustion zone where auto ignition occurs with the reactions going to completion in the transition between the combustor and turbine section. In the post-catalytic combustion zone, the combustion temperature is low and the residence time in the transition piece is short, hence minimizing thermal NO.sub.x.

Claims5

Dependent claims

A method of operating a combustor for a gas turbine under low, mid-range and high-load conditions, comprising the steps of:

(i) under low load conditions, flowing fuel and air into a diffusion flame combustion zone and causing combustion of the fuel in said zone to generate combustion products for flow in a direction downstream from said diffusion flow combustion zone;
(ii) under mid-range load conditions, supplying fuel to and mixing the fuel with the products of combustion flowing downstream from said diffusion flame combustion zone, causing combustion of the mixture in the presence of a catalyst in a catalytic combustion zone downstream of the diffusion flame combustion zone and continuing flow of combustion products therefrom in a downstream direction within a liner into a post-catalytic combustion zone;
and
(iii) under high-load conditions, introducing fuel and air downstream of the catalytic combustion zone and into the post-catalytic combustion zone by lean direct injection of fuel and air at locations radially inwardly of the liner without premixing outside the liner for mixing with combustion products from the diffusion flame combustion zone and the catalytic combustion zone and causing combustion of the mixture in the post-catalytic combustion zone.

1 more element

Dependencies are inferred from the claim text.

Catalytic combustor with lean direct injection of gas fuel for low emissions combustion and methods of operation

Life of this patent

Catalytic combustor with lean direct injection of gas fuel for low emissions combustion and methods of operation

Life of this patent

Abstract

Claims5