Natural gas fired combustion system for gas turbine engines

In a gas turbine engine comprising an air compressor, a high pressure turbine, a rotatable shaft driven by said turbine for driving said air compressor, a gaseous fuel combustion system comprising:

• an annular fuel-air distribution manifold surrounding the shaft of said engine in radially outwardly spaced relation thereto, said fuel air distribution manifold comprising a gas distribution annulus adjacent the shaft of said engine having a plurality of gas ejection nozzles extending radially outwardly from a radially outer wall thereof, and an air distribution annulus surrounding said gas annulus in radially outwardly spaced relation thereto, said air annulus of the fuel-air distribution manifold having a radially outer wall with a plurality of radially opening fuel-air mixing channels therein radially aligned with the nozzles on the gas annulus of said fuel-air manifold, respectively;
• an annular combuster surrounding said fuel-air distribution manifold in radially outwardly spaced relation thereto;
• a fuel duct for conducting a gaseous fuel to the gas annulus of said fuel-air manifold;
• an air duct for conducting compressed air from said air compressor to the air annulus of said fuel-air manifold and to plurality of apertures in a wall of said combustor, each aperture respectively spaced radially outwardly from the air-fuel mixing channels in said fuel-air distribution's manifold, whereby the gaseous fuel and air are mixed in the fuel-air mixing channels and air only is injected into the combustor radially outwardly from said fuel-air mixing channels so as to produce a lean fuel-air mixture in said combustor radially outwardly from the fuel-air mixing channels.