Method for tuning valves for primary and secondary fuel circuit

A method for adjusting fuel flow to individual combustion chambers in a gas turbine having fuel nozzles for each combustion chamber, and manifolds for supplying fuel to at least one fuel nozzle in each combustion chamber, wherein the manifolds have flow metering devices for said fuel nozzles, said method comprising:

• a. supplying fuel to the combustion chambers through at least one of said manifolds;
• b. combusting the fuel in the combustion chambers and generating exhaust gases which drive the gas turbine;
• c. actuating the flow metering device corresponding to a selected one of the combustion chambers to vary fuel flowing to the selected combustion chamber while maintaining a constant fuel flow to the other combustion chambers;
• d. sensing a condition of the exhaust gases at various exhaust regions in the exhaust gases;
• e. identifying a region of the exhaust in which the sensed conditions varies in response to the actuation of the flow metering device;
• f. correlating the identified region to the corresponding combustion chamber, and
• g. adjusting the flow metering device for the corresponding combustion chamber while continuing to sense the condition of the exhaust gas at the identified region of the exhaust, wherein the adjustment and sensing of the condition is performed to minimize a rich or lean fuel flow to the corresponding combustion chamber.

A method to tune fuel flow to individual combustion chambers of a gas turbine comprising:

• a) measuring exhaust gas temperatures at a plurality of exhaust regions of the gas turbine;
• b) correlating one of the measured exhaust gas temperatures to one of the combustion chambers using a swirl chart relating the exhaust regions to corresponding combustion chambers;
• c) identifying at least one of the combustion chambers as operating at an air-fuel mixture substantially different from a representative air-fuel mixture for all chambers based on the measured exhaust gas temperature correlated to the identified chamber,
• d) adjusting a fuel flow to the identified at least one of the combustion chambers to minimize a difference between the air-fuel mixture in the identified combustion chamber and the representative air-fuel mixture, and
• e) repeating steps a to d for each of the combustion chambers and until the difference is reduced for a plurality of the combustion chambers.

A method to tune fuel flow to individual combustion chambers of a gas turbine comprising:

• a) measuring exhaust gas temperatures at a plurality of exhaust regions of the gas turbine;
• b) correlating one of the measured exhaust gas temperatures to one of the combustion chambers using a swirl chart relating the exhaust regions to corresponding combustion chambers, artificially elevating a fuel flow to a selected combustion chamber and observing a higher exhaust gas temperature for one of said exhaust gas regions to correlate the region to the selected chamber;
• c) identifying at least one of the combustion chambers as operating at an air-fuel mixture substantially different from a representative air-fuel mixture for all chambers based the measured exhaust gas temperature correlated to the identified chamber, and
• d) adjusting a fuel flow to the identified at least one of the combustion chambers to minimize a difference between the air-fuel mixture in the identified combustion chamber and the representative air-fuel mixture.

A method to adjust fuel flow to individual combustion chambers in a gas turbine having a fuel nozzle for each combustion chamber, a manifold for supplying fuel to the fuel nozzle for each combustion chamber, wherein the manifold includes a flow metering device regulating fuel flow to the fuel nozzles, said method comprising:

• a. supplying fuel to the combustion chambers through the manifold;
• b. combusting the fuel in the combustion chambers and generating exhaust gases from the combustion which drive the gas turbine;
• c. sensing temperatures of the exhaust gases at each of a plurality of positions arranged radially about an flow axis of the exhaust gases and generating a first exhaust temperature profile from the temperatures sensed in step c and before step d;
• d. actuating the flow metering device for a selected one of the combustion chambers to adjust fuel flowing to the selected combustion chamber and not adjusting fuel flow to the nozzles for the other combustion chambers;
• e. after step d, sensing temperatures of the exhaust gases at each of the positions arranged radially about the flow axis of the exhaust gases and generating a second exhaust temperature profile from the temperatures sensed in step e;
• f. comparing the first and second exhaust temperature profiles to determine a change in temperature of the exhaust gas due to the actuation of the flow metering device for the selected combustion chamber;
• g. correlating the change in the temperature of the exhaust gases to the selected combustion chamber, and
• h. repeating steps d through g wherein another of the combustion chamber becomes the selected combustion chamber.