Patent ID: 7162875

Claim:
A method of regulating fuel flow to a combustion turbine engine, said engine having a combustor including an inlet, an outlet, a primary combustion zone and at least one further combustion zone, the total fuel supplied to the combustor being divided between primary fuel supplied to said primary combustion zone and other fuel supplied to said at least one further combustion zone, the resulting of the fuel comprising regulating the fuel ratio of said primary fuel to said total fuel by the steps of a) determining the inlet and outlet temperatures at the inlet and outlet of said combustor; b) determining a first value representing a first predetermined property of said combustor from said inlet and outlet temperature; c) determining a second value representing a second predetermined property of the primary combustion zone from the current value of said fuel ratio and said first value; d) determining the temperature at the outlet of the primary combustion zone from the inlet temperatures and said second value; e) comparing the temperature at the outlet of the primary combustion zone with a predetermined temperature, thereby to derive a difference value and generating a control signal dependent on said difference value, and f) varying the primary fuel, thereby to vary said fuel ratio the varying of the primary fuel being such as to vary said control signal corresponding to a reduction in said difference value. wherein said first predetermined property is one of: the total enthalpy rise in said combustor, the equivalence ratio of said combustor, the fuel/air ratio of said combustor, the temperature rise across said combustor, the fuel flow through said combustor; and said second predetermined property is the corresponding one of: the enthalpy rise in said primary combustion zone, the equivalence ratio of said primary combustion zone, the fuel/air ratio of said primary combustion zone; the temperature rise across said primary combustion zone, or the fuel flow through the primary combustion zone.