Cap assembly for a bundled tube fuel injector

1. A cap assembly for a bundled tube fuel injector, comprising:

a. an impingement plate;

b. an aft plate disposed downstream from the impingement plate, the aft plate having a forward side axially separated from an aft side;

c. a tube passage that extends through the impingement plate and the aft plate;

d. a tube sleeve that extends through the impingement plate within the tube passage towards the aft plate, the tube sleeve having a flange at a forward end and an aft end axially separated from the forward end;

e. a retention plate positioned upstream from the impingement plate; and

f. a spring disposed between the retention plate and the flange, wherein the spring provides an axial force to maintain contact between at least a portion of the aft end of the tube sleeve and the forward side of the aft plate, wherein the tube sleeve is axially movable with respect to the impingement plate.

2. The cap assembly as in claim 1 , further comprising a washer disposed between the spring and the flange.

3. The cap assembly as in claim 1 , wherein the impingement plate defines a pocket that is coaxially aligned with the tube passage, the flange of the tube sleeve and the spring being disposed concentrically within the pocket.

4. The cap assembly as in claim 1 , wherein a portion of the aft end of the tube sleeve extends through the aft plate.

5. The cap assembly as in claim 1 , wherein the tube sleeve includes an inner surface radially separated from an outer surface and a plurality of cooling channels defined within the inner surface.

6. The cap assembly as in claim 5 , wherein the tube sleeve includes one or more cooling ports that provide for fluid communication through the tube sleeve into the cooling channels.

7. The cap assembly as in claim 6 , further comprising a cooling air plenum at least partially defined between the impingement plate and the aft plate, wherein the cooling port is in fluid communication with the cooling air plenum.

8. The cap assembly as in claim 1 , wherein the impingement plate and the aft plate at least partially define a center fuel nozzle passage that extends axially therethrough.

9. A combustor, comprising:

a. an end cover coupled to an outer casing that surrounds the combustor;

b. a bundled tube fuel injector disposed downstream from the end cover, the bundled tube fuel injector having a plurality of tubes that extend axially within the combustor, each of the tubes having an upstream end axially separated from a downstream end; and

c. a cap assembly that extends radially and circumferentially across the bundled tube fuel injector proximate to the downstream end of the tubes, the cap assembly comprising:

i. an impingement plate;

ii. an aft plate disposed downstream from the impingement plate, the aft plate having a forward side axially separated from an aft side;

iii. a tube passage that extends through the impingement plate and the aft plate;

iv. a tube sleeve that extends through the impingement plate towards the aft plate, the tube sleeve being disposed within the tube passage, the tube sleeve having a flange at a forward end and an aft end that is axially separated from the forward end, wherein one tube of the plurality of tubes extends within the tube sleeve;

d. a retention plate positioned upstream from the impingement plate; and

e. a spring disposed between the retention plate and the flange of the tube sleeve, wherein the spring provides an axial force to maintain contact between at least a portion of the aft end of the tube sleeve and the forward side of the aft plate, wherein the tube sleeve is axially movable with respect to the impingement plate.

10. The combustor as in claim 9 , further comprising a washer disposed between the spring and the flange.

11. The combustor as in claim 9 , wherein the impingement plate defines a pocket that is coaxially aligned with the tube passage, the flange of the tube sleeve and the spring being disposed within the pocket.

12. The combustor as in claim 9 , wherein a portion of the aft end of the tube sleeve extends through the aft plate.

13. The combustor as in claim 9 , wherein the impingement plate and the aft plate at least partially define a center fuel nozzle passage that extends axially therethrough.

14. The combustor as in claim 9 , wherein the tube sleeve includes an inner surface radially separated from an outer surface and a plurality of cooling channels defined within the inner surface between the tube and the tube sleeve.

15. The combustor as in claim 14 , wherein the tube sleeve includes one or more cooling ports that provide for fluid communication through the tube sleeve into the cooling channels.

16. The combustor as in claim 15 , further comprising a cooling air plenum at least partially defined between the impingement plate and the aft plate, wherein the cooling port is in fluid communication with the cooling air plenum.

17. A gas turbine, comprising:

a. a compressor;

b. a combustor disposed downstream from the compressor, wherein the combustor includes an end cover coupled to an outer casing;

c. a turbine disposed downstream from the combustor; and

d. wherein the combustor comprises a bundled tube fuel injector disposed downstream from the end cover, the bundled tube fuel injector having a plurality of tubes that extend axially within the combustor, each of the tubes having an upstream end axially separated from a downstream end, the cap assembly comprising:

i. an impingement plate;

ii. an aft plate disposed downstream from the impingement plate, the aft plate having a forward side axially separated from an aft side;

iii. a cooling air plenum at least partially defined between the impingement plate and the aft plate;

iv. a tube passage that extends through the impingement plate and the aft plate;

v. a tube sleeve that extends through the impingement plate and the cooling air plenum towards the aft plate, the tube sleeve being disposed within the tube passage, the tube sleeve having a flange at a forward end and an aft end that is axially separated from the forward end, wherein one tube of the plurality of tubes extends within the tube sleeve;

e. a retention plate positioned upstream from the impingement plate; and

f. a spring disposed between the retention plate and the flange of the tube sleeve, wherein the spring provides an axial force to maintain contact between at least a portion of the aft end of the tube sleeve and the forward side of the aft plate, wherein the tube sleeve is axially movable with respect to the impingement plate.

18. The gas turbine as in claim 17 , wherein a portion of the aft end of the tube sleeve extends through the aft plate.

19. The gas turbine as in claim 17 , wherein the tube sleeve includes an inner surface radially separated from an outer surface and a plurality of cooling channels defined within the inner surface between the tube and the tube sleeve.

20. The as turbine as in claim 19 , wherein the tube sleeve includes one or more cooling ports that provide for fluid communication between the cooling air plenum and the cooling channels.