Device and method for gas turbine unlocking
An aeroderivative gas turbine including an air intake plenum; a compressor with a compressor air intake in fluid communication with the air intake plenum; a combustor; a high pressure turbine; a power turbine. A forced air-stream generator is arranged in fluid communication with the air intake plenum. A shutter arrangement is provided in a combustion-air flow path, arranged and controlled to close the combustion-air flow path for pressurizing said air intake plenum by means of the forced air-stream generator to a pressure sufficient to cause pressurized air to flow through the aeroderivative air turbine.
1. A method for unlocking a locked rotor in an aeroderivative gas turbine of an aeroderivative gas turbine package following shut-down of the aeroderivative gas turbine, the aeroderivative gas turbine package comprising the aeroderivative gas turbine, an air intake plenum in fluid communication with a combustion-air flow path, a silencer arrangement comprising a plurality of adjacent silencer panels defining a plurality of air passageways in the combustion-air flow path, a shutter arrangement comprising a plurality of shutters, each shutter arranged to selectively open and close an associated air passageway of the plurality of air passageways, and a forced air-stream generator in fluid communication with the air intake plenum, the method comprising:
selectively closing the plurality of air passageways by actuating each shutter of the plurality of shutters from a respective first position corresponding to an open state of the associated air passageway of the plurality of air passageways to a respective second position corresponding to a closed state of the associated air passageway of the plurality of air passageways to prevent air from the forced air-stream generator from escaping through the combustion-air flow path; and
starting the forced air-stream generator and generating an overpressure in the air intake plenum sufficient to force pressurized air through the locked rotor of the aeroderivative gas turbine to cool and unlock the rotor.
2. The method according to claim 1 , wherein the overpressure ranges between 0.05 and 0.3 Bar above ambient pressure.
3. The method according to claim 1 , wherein the overpressure ranges between 0.1 and 0.15 Bar above ambient pressure.
4. The method according to claim 1 , wherein each shutter of the plurality of shutters is movably arranged at a respective air outlet aperture of the associated air passageway of the plurality of air passageways.
5. The method according to claim 1 , wherein actuating the plurality of shutters comprises pivoting each shutter of the plurality of shutters, about a respective axis, between the respective first position and the respective second position.
6. The method according to claim 1 , wherein the plurality of shutters are mechanically connected to one another and controlled by a single actuator to enable simultaneous movement of each shutter of the plurality of shutters from the respective first position to the respective second position.