Oxyfuel turbine system and method for oxidant control

A gas turbine system (1) comprising:

• a combustor adapted to combust fuel and oxidant and generate pressurized hot combustion gas;
• a turbine fluidly coupled to the combustor and rotated by expansion of the pressurized hot combustion gas from the combustor;
• a heat exchanger fluidly coupled to the turbine and adapted to chill expanded combustion gas exhausted from the turbine;
• a main oxidant supply line adapted to supply a main oxidant stream to the combustor through the heat exchanger;
• wherein in use the main oxidant stream flowing through the heat exchanger is in heat exchange with the combustion gas exhausted from the turbine, such that heat is transferred from the combustion gas to the main oxidant stream and the combustion gas is chilled;
• a recycle line adapted to recycle a first chilled combustion gas stream through the heat exchanger to the combustor as working fluid;
• a combustion gas removal line adapted to exhaust a second chilled combustion gas stream;
• a fuel supply line adapted to supply the fuel to the combustor;
• a fuel control valve along the fuel supply line adapted to adjust a fuel flowrate delivered to the combustor;
• and
• a secondary oxidant supply line coupled to the fuel supply line at a mixing point upstream of the fuel control valve;
• wherein the secondary oxidant supply line is adapted to feed a secondary oxidant stream in the fuel supply line.