Method and apparatus for detecting combustion conditions in combustors of a sequential combustion gas turbine engine

A gas turbine comprising:

• a compressor;
• a first combustor with a first combustion chamber and first burners;
• a first turbine downstream of said first combustor;
• a second combustor with a second combustion chamber and second burners downstream of said first turbine;
• a second turbine downstream of said second combustor;
• an inlet upstream of the compressor and a flue gas exit downstream of the second turbine;
• a recirculating device configured and arranged to recirculate part of the flue gas from the flue gas exit to the inlet;
• a plurality of species concentration sensors arranged within a gas flow of the gas turbine, the species concentration sensors configured to measure at least O2 concentration of the gas flow and concentration of at least one other species of the gas flow;
• and
• a control unit configured and arranged to control operation of the gas turbine, the species concentration sensors being in signal communication with the control unit;
• and
• wherein the control unit is configured to control fuel supply valves that are adjustable to facilitate a flow of fuel to the second burners to control a flow of fuel to the second combustor based on a measurement of an O2 profile of the gas flow that is based on measurements from the species concentration sensors located adjacent an outlet of the first turbine.

A gas turbine comprising:

• a compressor;
• a first combustor with a first combustion chamber and first burners;
• a first turbine downstream of said first combustor;
• a second combustor with a second combustion chamber and second burners downstream of said first turbine;
• a second turbine downstream of said second combustor;
• an inlet upstream of the compressor and a flue gas exit downstream of the second turbine;
• a recirculating device configured and arranged to recirculate part of the flue gas from the flue gas exit to the inlet;
• a plurality of species concentration sensors arranged within a gas flow of the gas turbine, the species concentration sensors configured to measure at least O2 concentration of the gas flow and concentration of at least one other species of the gas flow;
• and
• a control unit configured and arranged to control operation of the gas turbine, the species concentration sensors being in signal communication with the control unit;
• and
• wherein the control unit is configured to control fuel supply valves that are adjustable to facilitate a flow of fuel to the second burners to control a flow of fuel to the second combustor based on a measurement of an O2 concentration of the gas flow that is measured in the first combustor by the species concentration sensors located in the first combustor.