Center burner in a multi-burner combustor

A method of operating a combustor for a gas turbine wherein the combustor has a plurality of outer fuel nozzles in an annular array arranged about a center axis, with two of said plurality of outer fuel nozzles in said annular array being cross-fire nozzles aligned with cross-fire tubes and remaining outer fuel nozzles in said annular array being non-cross-fire nozzles, a center nozzle located on the center axis, and a flame detector, and wherein the annular array is supplied with fuel from at least two pre-mix fuel manifolds, and further wherein the center nozzle is supplied with fuel from a center nozzle pre-mix fuel manifold the method comprising:

• a) at ignition, supplying the center nozzle with fuel from the center nozzle pre-mix fuel manifold and the two cross-fire nozzles with fuel from one of said at least two pre-mix fuel manifolds;
• b) after detecting cross-fire with the flame detector, turning off fuel to the two cross-fire nozzles, supplying all fuel to the center nozzle, and accelerating through full speed no load to a part load by increasing fuel flow to the center nozzle;
• c) at said part load, begin transferring some pre-mix fuel away from the center nozzle and staging it to the outer fuel nozzles in the following sequence as total fuel flow is increased:
• 1) center nozzle+two cross-fire nozzles, 2) center nozzle+non-cross-fire nozzles, and 3) all outer fuel nozzles but not the center nozzle;
• d) as load is further increased, initiating pre-mix fuel supply to the center nozzle without adding to the supply of pre-mix fuel to the fuel nozzles in the annular array;
• and then
• e) supplying additional pre-mix fuel to all of the fuel nozzles in the annular array and the center nozzle to thereby uniformly increase the fuel/air ratio as the turbine load increases.