Premixed pilot nozzle for dry low NOx combustor

Claim 2

A combined diffusion and premix nozzle com­prising: a diffusion pilot comprising a fuel delivery pipe including an axial pipe having an inlet end and a discharge end; an air delivery pipe coaxial with the axial pipe and surrounding the axial pipe; and, a first swirler annulus disposed at the discharge end of the axial pipe between the axial pipe and the surrounding air delivery pipe; the fuel delivery pipe further including a plurali­ty of radial fuel distribution tubes extending outwardly from the axial pipe and located toward the inlet end of the axial pipe, the radial fuel distribution tubes extending beyond the circumference of the air delivery pipe; a premix chamber surrounding the diffusion pilot and including an inlet end and a discharge end, the radial fuel distribution tubes extending into the premix chamber; at least one fuel discharge hole in at least one radial fuel distribution tube, the fuel discharge hole directed toward the discharge end of the premix chamber; and, a second swirler annulus at the discharge end of the premix chamber between the air delivery pipe and the surrounding premix chamber.

Claim 3

An improved gas turbine combustor of the type including first and second combustion chambers intercon­nected by a throat region, said throat region being of reduced dimension compared to the first and second combustion chambers; a plurality of diffusion type primary fuel nozzles in annular array upstream from the first combustion chamber for introducing fuel into the first combustion chamber, each of the diffusion nozzles including an annular swirler for introducing pressurized air into the first combustion chamber for creating a combustible fuel air mixture; wherein the improvement comprises: a combined diffusion and premix nozzle positioned upstream from the second combustion chamber and having a discharge end directed into the second combustion chamber.

Claim 4

An improved gas turbine combustor of the type including first and second combustion chambers intercon­nected by a throat region, said throat region being of reduced dimension compared to the first and second combustion chambers; a plurality of diffusion type primary fuel nozzles in annular array upstream from the first combustion chamber for introducing fuel into the first combustion chamber, each of the diffusion nozzles including an annular swirler for introducing pressurized air into the first combustion chamber for creating a combustible fuel air mixture; wherein the improvement comprises: a combined diffusion and premix nozzle positioned upstream from the second combustion chamber and having a discharge end directed into the second combustion chamber.

Claim 5

The improvement recited in claim 2 wherein the combined diffusion and premix nozzle includes: a diffusion pilot comprising an axial fuel delivery pipe and an air delivery pipe surrounding the axial fuel delivery pipe; a diffusion pilot swirler annulus between the fuel delivery pipe and the air delivery pipe; a premix chamber surrounding the diffusion pilot; a plurality of fuel discharge tubes extending radially outwardly from the fuel delivery pipe through the air delivery pipe and into the premix chamber; at least one fuel discharge hole in at least one of the radial fuel distribution tubes directed toward the discharge end of the premix chamber whereby fuel is distributed into the premix chamber; and, a premix chamber swirler located adjacent the discharge end of the combined diffusion and premix chamber nozzle between the air delivery pipe and the premix chamber.

Claim 6

The improvement recited in claim 3 wherein the premix chamber is a truncated cone.

Claim 7

The improvement recited in claim 2 wherein the combined diffusion and premix nozzle is located in the center of the annular array of a plurality of primary nozzles and further includes a third swirler between the combined nozzle and a surrounding centerbody wall.

Claim 8

In a dual stage, dual mode low NOx combustor, a central fuel nozzle comprising: a diffusion pilot comprising a fuel delivery pipe including an axial pipe having an inlet end and a discharge end; an air delivery pipe coaxial with the axial pipe and surrounding the axial pipe; and, a first swirler annulus disposed at the discharge end of the axial pipe between the axial pipe and the surrounding air delivery pipe; the fuel delivery pipe further including a plurali­ty of radial fuel distribution tubes extending outwardly from the axial pipe and located toward the inlet end of the axial pipe, the radial fuel distribution tubes extending beyond the circumference of the air delivery pipe; a premix chamber surrounding the diffusion pilot and including an inlet end and a discharge end, the radial fuel distribution tubes extending into the premix chamber; at least one fuel discharge hole in at least one radial fuel distribution tube, the fuel discharge hole directed toward the discharge end of the premix chamber; a second swirler annulus at the discharge end of the premix chamber between the air delivery pipe and the surrounding premix chamber; a cup positioned downstream from the discharge end of the central nozzle and a centerbody wall surrounding the central fuel nozzle; and, a third swirler annulus between the centerbody wall and the cup.

Claim 9

In a dual stage, dual mode low NOx combustor, a central fuel nozzle comprising: a diffusion pilot comprising a fuel delivery pipe including an axial pipe having an inlet end and a discharge end; an air delivery pipe coaxial with the axial pipe and surrounding the axial pipe; and, a first swirler annulus disposed at the discharge end of the axial pipe between the axial pipe and the surrounding air delivery pipe; the fuel delivery pipe further including a plurali­ty of radial fuel distribution tubes extending outwardly from the axial pipe and located toward the inlet end of the axial pipe, the radial fuel distribution tubes extending beyond the circumference of the air delivery pipe; a premix chamber surrounding the diffusion pilot and including an inlet end and a discharge end, the radial fuel distribution tubes extending into the premix chamber; at least one fuel discharge hole in at least one radial fuel distribution tube, the fuel discharge hole directed toward the discharge end of the premix chamber; a second swirler annulus at the discharge end of the premix chamber between the air delivery pipe and the surrounding premix chamber; a cup positioned downstream from the discharge end of the central nozzle and a centerbody wall surrounding the central fuel nozzle; and, a third swirler annulus between the centerbody wall and the cup.