Gas turbine combustor including a diffusion nozzle assembly with a double cylindrical structure

A gas turbine combustor comprising:

• a cylindrical outer casing having one end opening closed by a header plate;
• a combustor liner disposed inside the outer casing and provided with an inner combustor chamber which is divided into a first-stage combustion region on a side of the header plate and a second-stage combustion region formed on a downstream side of the first-stage combustion region;
• and
• a fuel supplying means including a first-stage fuel supply means mounted to the header plate for injecting a first-stage fuel to the first-stage combustion region and a second-stage fuel supply means mounted to the header plate for injecting a second-stage fuel previously mixed in a lean fuel state,
• said first-stage fuel supply means comprising a first-stage fuel nozzle assembly which supplies the first-stage fuel and which is formed by combining a diffusion combustion nozzle acting as a pilot combustion nozzle and a pre-mixture combustion nozzle disposed independently from the diffusion combustion nozzle,
• said diffusion combustion nozzle being of a double cylindrical structure having a fuel passage portion extending in an axial direction thereof and an air passage portion formed in an outer peripheral portion of said fuel passage portion between the diffusion combustion nozzle and the pre-mixture combustion nozzle, said air passage portion being provided, on the first-stage combustion region side, with a first swirler means for imparting a swirling motion to air, and a fuel injection port for injecting fuel from the fuel passage portion,
• said fuel passage portion formed in said diffusion combustion nozzle being provided with a first fuel passage portion at a central portion thereof capable of supplying the first-stage fuel and a second fuel passage portion capable of supplying the first-stage fuel in a quantity different from the supply quantity through the first fuel passage portion, said first and second fuel passage portions being formed independently from each other,
• said pre-mixture combustion nozzle being disposed so as to concentrically surround the diffusion combustion nozzle for supplying the pre-mixture gas of air and fuel to the first-stage combustion region, said pre-mixture combustion nozzle having a double cylindrical structure having an annular fuel passage and an annular air passage surrounding the annular fuel passage, said annular air passage having an inlet side portion to which a second swirler means is disposed for causing swirling motion to the air, and a plurality of fuel injection nozzles being disposed in the annular air passage for forming an air and fuel pre-mixture region, and
• said second fuel supply means being provided with a plurality of fuel nozzles and a premixing portion for premixing air and fuel, and supplying the pre-mixture air and fuel to the second combustion region.