Fuel lance for a gas turbine engine including outer helical grooves

1. A fuel lance useful for introducing fuel into a gas flow in a combustor of a gas turbine engine, the lance comprising:

an elongate lance body including a generally helically shaped region through which fuel can be introduced into the gas flow, wherein the helically shaped region comprises a helical groove on the outer surface of the lance extending generally in the axial direction of the lance;

at least one fuel outlet configured and arranged to introduce fuel into the gas flow, positioned on the surface of the helical groove; and

wherein the at least one fuel outlet comprises a plurality of fuel outlets arranged on the surface of the helical groove and spaced apart in the axial and/or circumferential and/or radial directions.

2. A fuel lance according to claim 1 , wherein a diameter of the fuel lance in a region where fuel is introduced into the gas flow is not constant in the axial direction.

3. A fuel lance according to claim 1 , wherein the helically shaped region includes a projection on the outer surface of the lance extending generally in the axial direction of the lance.

4. A fuel lance according to claim 1 , further comprising:

multiple fuel passages extending through the lance body, configured and arranged to introduce different fuels into the gas flow.

5. A fuel lance according to claim 4 , further comprising:

a first fuel outlet in the surface of the groove and a second fuel outlet in the outer surface of the lance;

wherein the multiple fuel passages comprise a first fuel passage configured and arranged to supply a first fuel to the first fuel outlet and a second fuel passage configured and arranged to supply a second fuel to the second fuel outlet.

6. A fuel lance according to claim 1 , further comprising:

a lance tip; and

a central passage configured and arranged to supply oil to the lance tip.

7. A fuel lance according to claim 1 , wherein each of the plurality of fuel outlets comprises a hole or slot.

8. A fuel lance according to claim 1 , wherein each of the plurality of fuel outlets is arranged so that fuel is introduced into the groove in an axial or radial direction.

9. A fuel lance according to claim 1 , wherein each of the plurality of fuel outlets is arranged so that the fuel is introduced into the groove in a tangential direction.

10. A fuel lance according to claim 1 , further comprising:

a hydrogen rich fuel flowing through the lance body and into the gas flow.

11. A gas turbine engine having sequential combustion, the engine comprising:

a first combustor configured and arranged to produce hot gas;

a second combustor downstream of the first combustor, configured and arranged to receive said hot gas from the first combustor; and

a fuel lance according to claim 1 in the second combustor, configured and arranged to introduce fuel into the hot gas.

12. A method of operating a sequential combustion gas turbine, the method comprising:

producing hot gas in a first combustor;

receiving said hot gas in a second combustor downstream of the first combustor; and

directly introducing fuel into the hot gas in the second combustor with a fuel lance according to claim 1 , said hot gas flowing around the lance.

13. A method according to claim 12 , further comprising:

receiving hot gas formed in the first combustor in a first turbine downstream of the first combustor and upstream of the second combustor; and

passing said hot gas from said first turbine to said second combustor.

14. A method according to claim 13 , further comprising:

receiving hot gas formed in the second combustor in a second turbine downstream of the second combustor.