Load rejection and recovery using a secondary fuel nozzle
AssigneeALSTOM Technology Ltd
InventorsNicolas Demougeot, Jon Glende, Peter Stuttaford
Life of this patent
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Abstract
A system and way for controlling a gas turbine engine in the event of a partial or full load rejection from a generator is disclosed. Upon detection of a partial or full load rejection, the fuel flow of the combustor is directed to a secondary circuit of a secondary fuel nozzle to maintain a flame in a downstream chamber of the combustor. By maintaining the flame in the downstream chamber while the engine speed is controlled, the recovery process to a load condition avoids use of spark ignition system and flame detectors in the upstream chamber.
Claims19
A method of controlling a gas turbine engine during a load rejection event, the method comprising:
- detecting an opening of one or more breakers that interrupts normal operation of the gas turbine engine;
- shifting all fuel flow for a combustor previously split between a plurality of primary fuel nozzles and a secondary fuel nozzle to only a secondary fuel circuit of the secondary fuel nozzle, while excluding a transfer fuel circuit of the secondary fuel nozzle, and while changing a main gas control valve position to a first setting;
- wherein the primary fuel nozzles are located in an annular array about the secondary fuel nozzle, the primary fuel nozzle located proximate an upstream chamber and adapted for injecting fuel into the upstream chamber during normal operation;
- and wherein the secondary fuel nozzle comprises the secondary fuel circuit and the transfer circuit is located along a centerline of the gas turbine engine, the secondary fuel circuit adapted to pass fuel to a transfer circuit proximate a downstream chamber to establish a secondary flame in the downstream chamber during normal operation;
- holding the fuel flow at the first setting;
- changing the main gas control valve to a second setting;
- holding the fuel flow at the second setting until the gas turbine engine returns to a predetermined operating speed condition;
- releasing the main gas control valve to a normal fuel control setting;
- closing the one or more breakers;
- confirming the one or more breakers are closed;
- and,
- re-loading the gas turbine engine and returning the combustor to a premix operating mode.
A control system for a gas turbine engine comprising a processing device having a memory component capable of storing one or more sets of computer-executable instructions for:
- a) identifying a load rejection event;
- b) adjusting a plurality of fuel control valves in fluid communication with a fuel source and at least a primary and secondary fuel circuit of one or more combustors of the gas turbine engine;
- c) directing the plurality of fuel control valves to direct fuel flow to only a secondary fuel circuit of a secondary fuel nozzle, while excluding a transfer fuel circuit of the secondary fuel nozzle, until the engine speed is stabilized, the secondary fuel nozzle, comprising the secondary fuel circuit and the transfer circuit, is located along a centerline of the gas turbine engine, the secondary fuel circuit adapted to pass fuel to a transfer circuit proximate a downstream chamber to establish a secondary flame in the downstream chamber during normal operation;
- and
- d) adjusting the plurality of fuel control valves to increase fuel flow as engine speed and load increase.
A powerplant comprising:
- a gas turbine engine;
- a generator coupled to the gas turbine engine;
- a main breaker removably coupled to the generator;
- a plant electrical network in communication with the generator through the main breaker;
- a power grid in communication with the generator through a secondary breaker;
- and,
- a control system associated with the gas turbine engine having a set of computer executable instructions embodied thereon for performing a method of controlling fuel flow to the gas turbine engine, such that upon detection of a load rejection event, fuel flow is directed exclusively to a secondary fuel nozzle for injection into a downstream chamber of a combustor so as to maintain flame stability in the combustor while reducing speed of a turbine, the secondary fuel nozzle having a secondary fuel circuit of the secondary fuel nozzle and a transfer fuel circuit, wherein the fuel flow is excluded from the transfer fuel circuit of the secondary fuel nozzle.
Dependencies are inferred from the claim text.