Patent ID: 8683808

Claim:
A gas turbine engine comprising: a combustor having a first interior in which a first fuel supplied thereto by a fuel circuit is combustible; a turbine, including rotating turbine blades, into which products of at least the combustion of the first fuel are receivable to power the rotation of the turbine blades; a transition zone, including a second interior in which a second fuel supplied thereto by the fuel circuit and the products of the combustion of the first fuel are combustible, the transition zone being disposed to fluidly couple the combustor and the turbine to one another; a plurality of late lean fuel injectors, which are structurally supported by the transition zone and coupled to the fuel circuit, and which are configured to supply the second fuel to the second interior in any one of a single axial stage, multiple axial stages, a single axial circumferential stage and multiple axial circumferential stages, wherein the fuel circuit comprises a first part that delivers the first fuel to the first interior, multiple branches of a second part that deliver the second fuel to the second interior and multiple valves respectively associated with each of the plurality of the fuel injectors by which at least the second fuel and air are deliverable into the plurality of the fuel injectors from the multiple branches, respectively, the fuel circuit connected to two different sources of fuel comprising a first source and an alternate source of fuel, the first source and alternate source of fuel each being fluidly connectable to the first part and second part of the fuel circuit, and a blend of the first and alternate sources of fuel being fluidly connectable to the first part and second part of the fuel circuit; and a control system coupled to the multiple valves of the fuel circuit and configured to control relative amounts of the first and second fuels supplied by the fuel circuit to the first and second interiors.