Abstract: In a gas turbine having a plurality of combustors, each having an annular array of outer fuel nozzles arranged about a center axis, an improved construction is provided wherein each combustor has a center nozzle located on the center axis. Various methods of operating the improved combustor are also disclosed.

Abstract: In a gas turbine having a plurality of combustors, each having an annular array of outer fuel nozzles arranged about a center fuel nozzle. A method for operating the combustors wherein the annular array is supplied with fuel from a diffusion manifold and at least one pre-mix manifold, and further wherein the center nozzle is supplied with fuel from a center premix manifold includes the steps of:a) at start-up, supplying some of the annular array nozzles with diffusion fuel;b) at part speed supplying pre-mix fuel to one of the nozzles in the annular array;c) at full speed, part load, transferring the annular array nozzles receiving diffusion fuel to pre-mix fuel;d) as load is increased supplying pre-mix fuel to the center nozzle; and thene) supplying additional pre-mix to all nozzles as load increases.

Abstract: In a gas turbine having a plurality of combustors, each having an annular array of outer fuel nozzles arranged about a center axis, an improved construction is provided wherein each combustor has a center nozzle located on the center axis. Various methods of operating the improved combustor are also disclosed.

Abstract: A fuel nozzle for a gas turbine includes a nozzle body having a tip portion, the nozzle body including an inner tube defining an axially extending air passage; an intermediate tube concentrically arranged and radially spaced from the inner tube and defining a diffusion fuel passage therebetween; and an outer tube concentrically arranged and radially spaced from the intermediate tube and defining a premix fuel passage therebetween. The outer tube has a plurality of radially extending injectors in communication with the premix fuel passage. The premix fuel passage is further defined in part by an outer tube wall portion formed with at least one weakened region adapted to burn through in the event of a flashback, thereby causing a substantial portion of premix fuel to bypass the injectors and to exit the nozzle body at the at least one weakened region. A related method is also disclosed.

Abstract: A method of operating a combustor for a turbine in the premixed mode includes flowing fuel through a symmetrical annular array of fuel nozzles to provide an asymmetrical fuel pattern across the combustor. Each nozzle includes an air swirler and the fuel is injected at axially spaced locations on opposite sides of the swirler. The asymmetrical fuel flow is provided during a diffusion mode of operation prior to transition between the diffusion mode and also during the transition. Near full power, the fuel is supplied equally among the fuel nozzles operating in the premixed mode. The asymmetric fuel flow stabilizes the combustor and inhibits high amplitude combustion noise and the axial staging of the fuel achieves low emission operation in the premixed mode.

Abstract: A method of operating a combustor for a turbine includes flowing fuel through a symmetrical annular array of fuel nozzles to provide an asymmetrical fuel pattern across the combustor. The asymmetrical fuel flow is provided during a diffusion mode of operation prior to transition between the diffusion mode and a premixed mode of operation, during the transition and during the premixed mode of operation. Near full power, the fuel is supplied equally among the fuel nozzles operating in the premixed mode. The asymmetric fuel flow stabilizes the combustor and inhibits high amplitude combustion noise while achieving low emission operation in the premixed mode.

Abstract: In a gas turbine (10), a plurality of combustors (14), each having a plurality of fuel nozzles (32) arranged about a longitudinal axis of the combustor, and a single combustion zone (70), each fuel nozzle having a diffusion passage (74) and a premix passage (60), the premix passage communicating with a plurality of premix fuel distribution tubes (66) located within a dedicated premix tube (46) adapted to mix the premix fuel and combustion air prior to entry into the single combustion zone (70) located downstream of the premix tube (46).