Abstract: A method of igniting liquid fuel in a turbomachine combustor is provided. The method includes a step of initiating a flow of gaseous fuel from a gaseous fuel supply to a gaseous fuel nozzle. The method further includes a step of initiating a flow of liquid fuel from a liquid fuel supply to a primary liquid fuel cartridge. After initiating both the flow of gaseous fuel and the flow of liquid fuel, the method includes a step of igniting the flow of gaseous fuel and the flow of liquid fuel with an igniter. The method further includes a step of terminating the flow of gaseous fuel from the gaseous fuel supply to the gaseous fuel nozzle.

Abstract: A method of igniting liquid fuel in a turbomachine combustor is provided. The method includes a step of initiating a flow of gaseous fuel from a gaseous fuel supply to a gaseous fuel nozzle. The method further includes a step of initiating a flow of liquid fuel from a liquid fuel supply to a primary liquid fuel cartridge. After initiating both the flow of gaseous fuel and the flow of liquid fuel, the method includes a step of igniting the flow of gaseous fuel and the flow of liquid fuel with an igniter. The method further includes a step of terminating the flow of gaseous fuel from the gaseous fuel supply to the gaseous fuel nozzle.

Abstract: Combustors, gas turbines, and associated methods of operation are provided. A method for operating a combustor includes firing a bundled tube fuel nozzle assembly within a combustion liner of the combustor to generate combustion gases at a first temperature within a first combustion zone length. The method further includes firing a fuel injector downstream from the bundled tube fuel nozzle assembly within the combustion liner of the combustor to generate combustion gases at a second temperature within a second combustion zone length. The first combustion zone length is less than the second combustion zone length. The combustion gases travel through the first combustion zone length in a first time period and through the second combustion zone length in a second time period. The second time period is less than the first time period.

Abstract: A method for selectively operating a combustor head end assembly is provided. The combustor head end assembly includes a plurality of bundled tube fuel nozzles. The method includes opening a first fuel circuit of a plurality of fuel circuits. The first fuel circuit of the plurality of fuel circuits is fluidly coupled to a first nozzle group, and the first nozzle group includes one bundled tube fuel nozzle of the plurality of bundled tube fuel nozzles. The method further includes adjusting an airflow received by the plurality of bundled tube fuel nozzles in response to opening the first fuel circuit of the plurality of fuel circuits. The airflow is adjusted based on an emissions output requirement corresponding with the first nozzle group. The method also includes firing the first nozzle group.

Abstract: A combustion system includes a head end comprising a liquid fuel cartridge. The liquid fuel cartridge has liquid fuel injection ports and is configured to produce combustion products via a diffusion flame. A liner is configured to deliver the combustion products from the head end to an aft frame, and an injector having an outlet is located along the liner between the head end and the aft frame. The injector outlet delivers a stream of oxidant inwardly into the liner, such that a mixedness and a velocity of the combustion products are increased prior to the combustion products reaching the aft frame. A method of producing combustion products having characteristics of a premixed flame in a liquid fuel combustion system is also provided herein.

Abstract: The present disclosure is directed to an end cover assembly for a combustor of a turbomachine. The end cover assembly includes an end cover and a bundled tube fuel nozzle assembly positioned downstream from the end cover. The bundled tube fuel nozzle assembly includes a plurality of fuel nozzle tubes. A flame detector sight tube couples to the end cover. The flame detector sight tube is aligned with one of the fuel nozzle tubes.

Abstract: A system and method for igniting liquid fuel in a gas turbine combustor is provided. A liquid fuel cartridge, which is located within the head end, is in flow communication with a liquid fuel supply. A gaseous fuel nozzle is located proximate the liquid fuel cartridge and in flow communication with an auxiliary gaseous fuel supply. A controller is in communication with the liquid fuel supply, the auxiliary gaseous fuel supply, and an igniter located proximate or within the head end. The controller is configured to sequentially: initiate a gaseous fuel flow from the auxiliary gaseous fuel supply to the gaseous fuel nozzle; initiate the igniter to combust the gaseous fuel flow; initiate a liquid fuel flow from the liquid fuel supply to the liquid fuel cartridge; and terminate the gaseous fuel flow from the auxiliary gaseous fuel supply.

Abstract: A system and method for igniting liquid fuel in a gas turbine combustor is provided. A liquid fuel cartridge, which is located within the head end, is in flow communication with a liquid fuel supply. A gaseous fuel nozzle is located proximate the liquid fuel cartridge and in flow communication with an auxiliary gaseous fuel supply. A controller is in communication with the liquid fuel supply, the auxiliary gaseous fuel supply, and an igniter located proximate or within the head end. The controller is configured to sequentially: initiate a gaseous fuel flow from the auxiliary gaseous fuel supply to the gaseous fuel nozzle; initiate the igniter to combust the gaseous fuel flow; initiate a liquid fuel flow from the liquid fuel supply to the liquid fuel cartridge; and terminate the gaseous fuel flow from the auxiliary gaseous fuel supply.

Abstract: A combustion system includes a head end comprising a liquid fuel cartridge. The liquid fuel cartridge has liquid fuel injection ports and is configured to produce combustion products via a diffusion flame. A liner is configured to deliver the combustion products from the head end to an aft frame, and an injector having an outlet is located along the liner between the head end and the aft frame. The injector outlet delivers a stream of oxidant inwardly into the liner, such that a mixedness and a velocity of the combustion products are increased prior to the combustion products reaching the aft frame. A method of producing combustion products having characteristics of a premixed flame in a liquid fuel combustion system is also provided herein.

Abstract: The present disclosure is directed to an end cover assembly for a combustor of a turbomachine. The end cover assembly includes an end cover and a bundled tube fuel nozzle assembly positioned downstream from the end cover. The bundled tube fuel nozzle assembly includes a plurality of fuel nozzle tubes. A flame detector sight tube couples to the end cover. The flame detector sight tube is aligned with one of the fuel nozzle tubes.

Abstract: A fuel nozzle for use in a gas turbine includes a pre-mix flow passage for directing a flow segment of a flow of a working fluid through the fuel nozzle. A first swirler vane and a second swirler vane extend within the pre-mix flow passage. The first swirler vane provides a first wake region within the flow segment. The second swirler vane provides a second wake region within the flow segment. A fuel injection peg is disposed downstream from the first swirler vane and the second swirler vane. The fuel injection peg is positioned within the flow segment between the first wake region and the second wake region.

Abstract: A method of operating a combustor having a central nozzle and a plurality of outer nozzles surrounding the central nozzle is provided. The method includes providing a liquid fuel to only the plurality of outer nozzles at a specified total energy input. The method includes decreasing the liquid fuel to the plurality of outer nozzles while simultaneously increasing a gas fuel to the central nozzle and the plurality of outer nozzles to substantially maintain the specified total energy input. The method includes supplying a fuel-air ratio of the gas fuel to the central nozzle that exceeds a threshold value such that a central nozzle flame is anchored. An air-fuel ratio of the gas fuel to the plurality of outer nozzles is less than the threshold value such that a plurality of outer nozzle flames are lifted until a purge flow is supplied to the outer nozzles.

Abstract: A fuel nozzle for use in a gas turbine includes a pre-mix flow passage for directing a flow segment of a flow of a working fluid through the fuel nozzle. A first swirler vane and a second swirler vane extend within the pre-mix flow passage. The first swirler vane provides a first wake region within the flow segment. The second swirler vane provides a second wake region within the flow segment. A fuel injection peg is disposed downstream from the first swirler vane and the second swirler vane. The fuel injection peg is positioned within the flow segment between the first wake region and the second wake region.

Abstract: A gas turbine includes a compressor section, a combustion section downstream from the compressor section, a turbine section downstream from the combustion section, and a controller. The controller controls the operation of the gas turbine at a reduced load, and is capable of querying a database including multiple sets of operational parameters for the gas turbine correlated with at least one measured output response at each set of operational parameters. One of the sets of operational parameters provides a desired gas turbine load that meets a target level for the output response. Related methods are also disclosed.

Abstract: A method of operating a combustor having a central nozzle and a plurality of outer nozzles surrounding the central nozzle is provided. The method includes providing a liquid fuel to only the plurality of outer nozzles at a specified total energy input. The method includes decreasing the liquid fuel to the plurality of outer nozzles while simultaneously increasing a gas fuel to the central nozzle and the plurality of outer nozzles to substantially maintain the specified total energy input. The method includes supplying a fuel-air ratio of the gas fuel to the central nozzle that exceeds a threshold value such that a central nozzle flame is anchored. An air-fuel ratio of the gas fuel to the plurality of outer nozzles is less than the threshold value such that a plurality of outer nozzle flames are lifted until a purge flow is supplied to the outer nozzles.

Abstract: A turbomachine includes a compressor, a turbine operatively connected to the compressor, and a combustion assembly fluidly connected between the compressor and the turbine. The combustion assembly includes an end cover including a plurality of fuel circuits, a fuel distributing flange fluidly connected to at least one of the plurality of fuel circuits, a nozzle assembly fluidly linked to the at least one of the plurality of fuel circuits, and a fuel distribution system configured and disposed to deliver fuel to the fuel distributing flange. The fuel distribution system is selectively activated to stage fuel delivery to the at least one of the plurality of fuel circuits at a pressure sufficient to achieve atomization at the nozzle assembly without requiring a supplemental atomization air flow prior to delivering fuel to others of the plurality of fuel circuits at a pressure to achieve atomization without requiring a supplemental atomization air flow.

Abstract: Methods, systems, and program products for improved accuracy in estimating a combustion reference temperature (CRT) are provided. In one embodiment, the invention provides a method of estimating a combustion reference temperature (CRT) in a gas turbine, the method comprising: obtaining a measurement of at least one dynamic operating condition of the gas turbine selected from a group consisting of: an ambient condition, a compressor condition, a fuel condition, and a turbine condition; inputting a measurement of the at least one operating condition into a physics-based model; calculating at least one estimated internal state for the gas turbine using the physics-based model; and calculating an estimated CRT based on the at least one gas turbine internal state.

Abstract: A nozzle for gas turbine includes a tubular nozzle body; and a plurality of hollow fuel injection pegs extending radially from the tubular nozzle body at a location between forward and aft ends of the tubular nozzle body; wherein each of the plurality of hollow fuel injection pegs has an external tear-drop cross-sectional shape, and a fuel passage in each of the hollow injection pegs has a substantially matching internal tear-drop cross-sectional shape.

Abstract: A turbomachine includes a compressor, a turbine operatively connected to the compressor, and a combustion assembly fluidly connected between the compressor and the turbine. The combustion assembly includes an end cover including a plurality of fuel circuits, a fuel distributing flange fluidly connected to at least one of the plurality of fuel circuits, a nozzle assembly fluidly linked to the at least one of the plurality of fuel circuits, and a fuel distribution system configured and disposed to deliver fuel to the fuel distributing flange. The fuel distribution system is selectively activated to stage fuel delivery to the at least one of the plurality of fuel circuits at a pressure sufficient to achieve atomization at the nozzle assembly without requiring a supplemental atomization air flow prior to delivering fuel to others of the plurality of fuel circuits at a pressure to achieve atomization without requiring a supplemental atomization air flow.

Abstract: A combustor having a combustion liner and at least one combustor orifice assembly, the combustor orifice assembly comprising a boss, an orifice plate that defines an orifice, the orifice plate having a bottom surface that is adapted to be received by the boss, and a retaining ring, whereby the orifice plate is retained between the retaining ring and the boss.