Fuel injection
A direct injection fuel system is shown for injecting hydrogen fuel into a gas turbine combustor. The fuel injection system includes a plurality of fuel injector blocks. Each fuel injector block includes a fuel admission duct having an inlet for receiving hydrogen fuel from a fuel supply, an outlet for delivering hydrogen fuel into the combustor and a central axis extending from said inlet to said outlet. Each fuel injector block also includes an air admission duct located around the periphery of the fuel admission duct, having an inlet for receiving air from a diffuser and an outlet for delivering air into the combustor for mixing with the hydrogen fuel.
1. A direct injection fuel system for injecting hydrogen fuel into a gas turbine combustor, the direct injection fuel system comprising a plurality of fuel injector blocks, each of the plurality of fuel injector blocks includes:
a fuel admission duct having an inlet for receiving the hydrogen fuel from a fuel supply, an outlet for delivering the hydrogen fuel into the gas turbine combustor and a central axis extending from said inlet to said outlet;
an air admission duct located around the fuel admission duct, having an inlet for receiving an air from a diffuser and an outlet for delivering the air into the gas turbine combustor for mixing with the hydrogen fuel, wherein:
the air admission duct comprises a constant area section from the inlet of the air admission duct to a first intermediate position, and a decreasing area section between the first intermediate position to the outlet of the air admission duct,
the fuel admission duct is defined by a peripheral wall extending from the inlet to the outlet of the fuel admission duct, said peripheral wall having a chamfered section that is angled at a first angle relative to the central axis and extends between a second intermediate position and the outlet of the fuel admission duct,
the decreasing area section is defined by an inclined portion of a wall of the air admission duct inclined inward at a second angle relative to the central axis; and
the second angle of the inclined portion and the first angle of the chamfered section are inclined at a same angle relative to the central axis, and both of the first angle and the second angle are each between 15 and 20 degrees.
2. The direct injection fuel system of claim 1 , in which each of the air admission ducts is configured to inject the air at a non-zero angle relative to the respective central axis.
3. The direct injection fuel system of claim 1 , in which an area of the outlet of each of the air admission ducts is from 2 to 200 times greater than an area of the outlet of the respective fuel admission duct.
4. The direct injection fuel system of claim 3 , in which the area of the outlet of each of the air admission ducts is from 4 to 45 times greater than the area of the outlet of the respective fuel admission duct.
5. The direct injection fuel system of claim 3 , in which the area of the outlet of each of the air admission ducts is from 5 to 180 times greater than the area of the outlet of the respective fuel admission duct.
6. The direct injection fuel system of claim 3 , in which the area of the outlet of each of the air admission ducts is from 25 to 35 times greater than the area of the outlet of the respective fuel admission duct.
7. The direct injection fuel system of claim 1 , in which a maximum dimension of the outlet of each of the air admission ducts is from 2 to 15 times greater than a maximum dimension of the outlet of the respective fuel admission duct.
8. The direct injection fuel system of claim 7 , in which the maximum dimension of the outlet of each of the air admission ducts is from 4.3 to 6.75 times greater than the maximum dimension of the outlet of the respective fuel admission duct.
9. The direct injection fuel system of claim 1 , in which each of the air admission ducts is concentric with the respective fuel admission duct.
10. The direct injection fuel system of claim 9 , for each of the plurality of fuel injector blocks, an area of the inlet of the air admission duct is greater than an area of the outlet of the air admission duct.
11. The direct injection fuel system of claim 10 , for each of the plurality of fuel injector blocks, the area of the inlet of the air admission duct is from 1 to 1.5 times greater than the area of the outlet of the air admission duct.
12. The direct injection fuel system of claim 1 , wherein a number of the plurality of fuel injector blocks comprised in the direct injection fuel system is from 500 to 4000.
13. The direct injection fuel system of claim 1 , for each of the plurality of fuel injector blocks, the peripheral wall defined the fuel admission duct has:
a straight portion that is parallel to the central axis, and
the chamfered section,
wherein the straight portion and the chamfered section are directly connected at the second intermediate position.
14. The direct injection fuel system of claim 1 , for each of the plurality of fuel injector blocks, the wall of the air admission duct has:
a straight portion that is parallel to the central axis, and
the inclined portion,
wherein the straight portion and the inclined portion are directly connected at the first intermediate position.
15. The direct injection fuel system of claim 1 , for each of the plurality of fuel injector blocks, the chamfered section is located at an outer radial side of the peripheral wall and the inclined portion is located at an inner radial side of the wall of the air admission duct.
16. The direct injection fuel system of claim 1 , for each of the plurality of fuel injector blocks, the inclined portion is longer along the central axis than the chamfered section.