Patent ID: 8479520

Claim:
A gas turbine combustor comprising at least one main nozzle provided with an oil fuel path for passage of oil fuel and a gas fuel path for passage of gas fuel, wherein the main nozzle comprises a cylindrical central tube disposed at a center of the main nozzle and using an interior thereof as an oil fuel path through which oil fuel flows, a cylindrical outer tube disposed on an outermost periphery of the main nozzle, and a support tube disposed between the central tube and the outer tube, the central tube, the outer tube and the support tube each being formed independently, wherein the support tube has such an internal diameter as to form a clearance becoming an insulating air layer between the support tube and an outer periphery of the central tube, and the support tube includes a plurality of supporting portions formed on an axially upstream side and radially contacting an inner periphery of the outer tube, thereby forming a plurality of groove portions formed along an axial direction between the supporting portions, and a cylindrical portion formed on an axially downstream side and the cylindrical portion having an external diameter equal to or smaller than an external diameter of the groove portions, and wherein the outer tube and the support tube define the gas fuel path therebetween.