Load rejection and recovery using a secondary fuel nozzle

摘要

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.

主权项

1. 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.