Sequential combustion with dilution gas mixer

Abstract

The invention refers to a sequential combustor arrangement comprising a first burner, a first combustion chamber, a mixer for admixing a dilution gas via a dilution gas inlet to the hot gases leaving the first combustion chamber during operation, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection. The sequential combustor arrangement further includes four cooling zones with a cooling channel. During operation a cooling gas flows through the cooling channels. The disclosure further refers to a method for operating a gas turbine with such a sequential combustor arrangement.

Claims

1. A sequential combustor arrangement comprising: a first burner; a first combustion chamber; a mixer for admixing a dilution gas to the hot gases leaving the first combustion chamber during operation; a second burner; and a second combustion chamber arranged sequentially in a fluid flow connection, wherein the mixer is configured to guide combustion gases in a hot gas flow path extending between the first combustion chamber and the second burner; the mixer having a duct with an inlet at an upstream end configured for connection to the first combustion chamber and an outlet at a downstream end configured for connection to the second burner; a first combustion chamber cooling zone with a first cooling channel which is delimited by a first combustion chamber wall and a first jacket, which encloses the first combustion chamber wall; a mixer cooling zone with a second cooling channel which is delimited by a mixer wall and a second jacket, which encloses the mixer wall; a second burner cooling zone with a third cooling channel which is delimited by a second burner wall and a third jacket, which encloses the second burner wall; and a second combustion chamber cooling zone, with a fourth cooling channel which is delimited by a second combustion chamber wall and a fourth jacket, which encloses the second combustion chamber wall, the first, second, third, and fourth cooling channels being arranged such that a cooling gas will flow through the cooling channels during operation; the mixer having a dilution gas inlet directly connected to at least one exit of the compressor such that a first portion of compressed gas leaving the compressor will be admitted directly to the dilution gas inlet as a portion of the dilution gas without prior heat pick up in a cooling zone during operation; wherein the fourth cooling channel is connected to the at least one exit of the compressor to receive a second portion of the compressed gas from the compressor as a portion of the cooling gas to cool the second combustion chamber wall and subsequently pass the second portion of the compressed gas to the third cooling channel to cool the second burner wall during operation; and wherein the second cooling channel is connected to the at least one exit of the compressor such that a third portion of the compressed gas is passable into the second cooling channel as a portion of the cooling gas to cool the mixer wall during operation and the first cooling channel is connected adjacent to the dilution gas inlet such that at least some of the dilution gas bypasses the dilution gas inlet and passes to the first cooling channel to cool the first combustion chamber wall during operation.

2. The sequential combustor arrangement of claim 1, wherein the third cooling channel is connected to the mixer to feed the second portion of the compressed gas to the mixer as a portion of the dilution gas to be admixed with the hot gases during operation; and/or wherein the second cooling channel is connected to the mixer so that some of the third portion of the compressed gas is passable from the second cooling channel to the mixer as a portion of the dilution gas for admixing with the hot gases during operation.

3. The sequential combustor arrangement of claim 1, wherein at least three of the first, second, third, and fourth cooling channels are fluidly connected to each other in a row such that at least part of the cooling gas used for cooling in one cooling channel will be further used for sequentially cooling the other two cooling channels during operation.

4. The sequential combustor arrangement of claim 1, wherein the at least two cooling channels of the first, second, third, and fourth cooling channels are directly connected to the exit of the compressor such that compressed gas leaving the compressor will be admitted directly to the at least two cooling channels without prior heat pick up in an interposed cooling zone.

5. The sequential combustor arrangement of claim 1, wherein the second cooling channel is connected to the mixer so that some of the third portion of the compressed gas is passable from the second cooling channel into the mixer as a portion of the dilution gas for admixing with the hot gases from the first combustion chamber during operation.

6. The sequential combustor arrangement as claimed in claim 1, wherein at least one cooling channel of the first, second, third, and fourth cooling channels has an inlet at a downstream end with respect to a flow direction of hot gas and an outlet opening at an upstream end with respect to the flow direction of the hot gas and wherein at least part of the cooling gas flows in a counter flow to the hot gas flow direction during operation.

7. A method for operating a gas turbine with at least a compressor, a sequential combustor arrangement having a first burner, a first combustion chamber, a mixer for admixing a dilution gas to hot gases leaving the first combustion chamber, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection, the method comprising: guiding, via the mixer combustion gases in a hot gas flow path extending between the first combustion chamber and the second burner via a duct having an inlet at an upstream end configured for connection to the first combustion chamber and an outlet at a downstream end configured for connection to the second burner, the sequential combustor arrangement including a first combustion chamber cooling zone with a first cooling channel which is delimited by a first combustion chamber wall and a first jacket, which encloses the first combustion chamber wall, a mixer cooling zone with a second cooling channel which is delimited by a mixer wall and a second jacket, which encloses the mixer wall, a second burner cooling zone with a third cooling channel which is delimited by a second burner wall and a third jacket, which encloses the second burner wall, and a second combustion chamber cooling zone, with a fourth cooling channel which is delimited by a second combustion chamber wall and a fourth jacket, which encloses the second combustion chamber wall, the method comprising: feeding and guiding a cooling gas through the cooling channels, the feeding and guiding of the cooling gas through the cooling channels including: feeding a first portion of compressed gas from the compressor to the fourth cooling channel as a portion of the cooling gas to cool the second combustion chamber wall and subsequently passing the second portion of the compressed gas to the third cooling channel to cool the second burner wall, and feeding a second portion of the compressed gas into the second cooling channel as a portion of the cooling gas to cool the mixer wall; and admixing the dilution gas to the hot gases leaving the first combustion chamber in the mixer, the admixing of the dilution gas including: feeding a third portion of the compressed gas to a dilution gas inlet of the mixer without prior heat pick up in a cooling zone during operation; and bypassing a portion of the dilution gas past the dilution gas inlet to an adjacent inlet of the first cooling channel to cool the first combustion chamber wall.

8. The method of claim 7, wherein at least part of the cooling gas in a cooling channel flows in a counter flow to a hot gas flow direction, and/or at least part of the cooling gas in a cooling channel flows in a co-current flow to the hot gas flow direction.

9. The method of claim 8, wherein the mixer has a dilution gas exit connected to the compressor so that the third portion of the compressed gas passes from the compressor to the mixer for admixing without contacting the first combustion chamber wall, without contacting the second burner wall, and without contacting the second combustion chamber wall.

10. The method of claim 7, wherein the feeding and guiding of the cooling gas through the cooling channels occurs such that: a portion of the cooling gas is passed through the first cooling channel to the first burner in a direction that is counterflow to a main flow direction of hot gas flowing through the first combustion chamber, and/or a portion of the cooling gas is passed through the first cooling channel toward the second cooling channel in a direction that is co-current with the main flow direction of the hot gas flowing through the first combustion chamber.

11. The method of claim 7, comprising: feeding a portion of the compressed gas to a first burner that is upstream of the first combustion zone.

12. The method of claim 7, wherein at least two of the first cooling channel, the second cooling channel, the third cooling channel, and the fourth cooling channel are directly connected to the compressor such that compressed gas leaving the compressor will be admitted directly to these cooling channels without prior heat pick up in an interposed cooling zone.

13. The method of claim 7, wherein the admixing of the dilution gas to the hot gases leaving the first combustion chamber in the mixer also includes: feeding the first portion of the compressed gas from the third cooling channel to the mixer as a portion of the dilution gas for admixing with the hot gases.

14. The method of claim 13, wherein the admixing of the dilution gas to the hot gases leaving the first combustion chamber in the mixer also includes: passing some of the second portion of the compressed gas from the second cooling channel to the mixer as a portion of the dilution gas for admixing with the hot gases.

15. The method of claim 7, wherein the admixing of the dilution gas to the hot gases leaving the first combustion chamber in the mixer also includes: passing some of the second portion of the compressed gas from the second cooling channel to the mixer as a portion of the dilution gas for admixing with the hot gases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The disclosure, its nature as well as its advantages, shall be described in more detail below with the aid of the accompanying schematic drawings. Referring to the drawings:

(2) FIG. 1 shows a gas turbine with a sequential combustion arrangement with a mixer for admixing dilution gas and four cooling zones;

(3) FIG. 2 shows a sequential combustion arrangement with a cooling channel which is partly cooled by cooling gas in cocurent flow to the hot gas flow and partly cooled by a cooling gas in counter flow to the hot gas flow;

(4) FIG. 3 shows a sequential combustion arrangement with serial cooling of cooling zones and subsequent use of the cooling gas as dilution gas;

(5) FIG. 4 shows a sequential combustion arrangement with serial cooling of cooling zones and subsequent use of the cooling gas as dilution gas and subsequent use of cooling gas in the first burner;

(6) FIG. 5 shows a sequential combustion arrangement with cocurent cooling gas flow to the hot gas flow with subsequent use of the cooling gas as dilution gas and cooling gas flow in counter flow to the hot gas flow with subsequent use of the cooling gas as dilution gas;

(7) FIG. 6 shows a sequential combustion arrangement with subsequent use of cooling gas as dilution gas and direct injection of compressor exit gas as dilution gas;

(8) FIG. 7 shows a sequential combustion arrangement in can architecture and with a flame sheet burner;

(9) FIG. 8 shows a sequential combustion arrangement in can architecture and with a flame sheet burner, with serial cooling of cooling zones and subsequent use of the cooling gas as dilution gas and subsequent use of cooling gas in the first burner;

(10) FIG. 9 shows a sequential combustion arrangement, with a flame sheet burner, with serial cooling of cooling zones and subsequent use of the cooling gas as dilution gas.

DETAILED DESCRIPTION

(11) FIG. 1 shows a gas turbine 1 with a sequential combustor arrangement 4 according to the disclosure. It comprises a compressor 3, a sequential combustor arrangement 4, and a turbine 5.

(12) The sequential combustor arrangement 4 comprises a first burner 10, a first combustion chamber 11, and a mixer 12 for admixing a dilution gas 32 to the hot gases leaving the first combustion chamber 11 during operation. Downstream of the mixer 12 the sequential combustor arrangement 4 further comprises a second burner 13, and a second combustion chamber 14. The first burner 10, first combustion chamber 11, mixer 12, second burner 13 and second combustion chamber 14 are arranged sequentially in a fluid flow connection. The sequential combustor arrangement 4 is housed in a combustor casing 31. The compressed gas 8 leaving the compressor 8 passes through a diffusor 30 for at least partly recovering the dynamic pressure of the gas leaving the compressor.

(13) The sequential combustor arrangement 4 further comprises a first combustion chamber cooling zone with a first cooling channel 15 which is delimited by the first combustion chamber wall 24 and a first jacket 20, which is enclosing the first combustion chamber wall 24. It comprises a mixer cooling zone with a second cooling channel 16 which is delimited by a mixer wall 25 and a second jacket 21, which is enclosing the mixer wall 25. It comprises a second burner cooling zone with a third cooling channel which is delimited by a second burner wall 26 and a third jacket 22, which is enclosing the second burner wall 26. It also comprises a second combustion chamber cooling zone with a fourth cooling channel 18, which is delimited by a second combustion chamber wall 27, and a fourth jacket 23, which is enclosing the second combustion chamber wall (27).

(14) Compressed gas 8 is fed into the first cooling channel 15 as cooling gas 33 at an upstream end (relative to the hot gas flow direction) and flows through the first cooling channel 15 parallel to the main flow direction of the hot gas flow in the first combustion chamber 11. After passing through the first cooling channel 15 the cooling gas 33 enters the second cooling channel for cooling the mixer. After at least partly cooling the mixer cooling gas 33 is fed into the dilution gas inlet 19 and admixed to the hot gas as dilution gas 32 in the mixer 12.

(15) Compressed gas 8 is also fed into the fourth cooling channel 18 as cooling gas 33 at a downstream end (relative to the hot gas flow direction) and flows in counterflow to the main flow direction of the hot gas flow in the second combustion chamber 14. After passing through the fourth cooling channel 18 the cooling gas 33 enters the third cooling channel 17 at a downstream end (relative to the hot gas flow direction) and flows in counterflow to the main flow direction of the hot gas flow in the second burner 13. After cooling the second combustion chamber wall 27 and the second burner wall 26 the cooling gas 33 is fed to the second burner 13. The cooling gas 33 can for example be fed to the second burner 13 as cooling gas, e.g. as film cooling gas or diffusion cooling. Part of the cooling gas 33 can already be fed to the hot gas 9 in the second combustion chamber 14 during cooling of the second combustion chamber wall 27 (not shown).

(16) Fuel can be introduced into the first burner 10 via a first fuel injection 28, mixed with compressed gas 8 which is compressed in the compressor 3, and burned in the first combustion chamber 11. Dilution gas 32 is admixed in the subsequent mixer 12. Additional fuel can be introduced into the second burner 13 via a second fuel injection 29, mixed with hot gas leaving the mixer 12, and burned in the second combustion chamber 14. The hot gas leaving the second combustion chamber 14 is expanded in the subsequent turbine 5, performing work. The turbine 5 and compressor 3 are arranged on a shaft 2.

(17) The remaining heat of the exhaust gas 7 leaving the turbine 5 can be further used in a heat recovery steam generator or boiler (not shown) for steam generation.

(18) In the example shown here compressed gas 8 is admixed as dilution gas 32. Typically compressor gas 8 is compressed ambient air. For gas turbines with flue gas recirculation (not shown) the compressor gas is a mixture of ambient air and recirculated flue gas.

(19) Typically, the gas turbine system includes a generator (not shown) which is coupled to a shaft 2 of the gas turbine 1. The gas turbine 1 further comprises a cooling system for the turbine 5, which is also not shown as it is not subject of the invention.

(20) Different exemplary embodiments of the cooling arrangement and of the burners are shown in FIGS. 2 to 8. For simplification only the sequential combustor arrangement 4 is shown in these Figures and the other gas turbine components such as compressor and turbine are omitted.

(21) The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in that the cooling gas 33 is fed to the fourth cooling channel 18 at a location between the upstream and downstream end of the fourth cooling channel 18. From the fed location part of the cooling gas 33 flows in counterflow to the main flow direction of the hot gas flow in the second combustion chamber 14. After passing through the fourth cooling channel 18 the cooling gas 33 enters the third cooling channel 17 at a downstream end like in the example of FIG. 1. The remaining cooling gas 33, which is fed into the fourth cooling channel 18 flows through the fourth cooling channel 18 parallel to the main flow direction of the hot gas flow in the second combustion chamber 14. After passing through the downstream end of the fourth cooling channel 18 the cooling gas 33 is used as cooling and sealing gas at the interface to the turbine.

(22) The embodiment of FIG. 3 differs from the embodiment of FIG. 1 in that the second cooling channel 16 and the third cooling channel 17 are fluidly connected and in that cooling gas 33 continues to flow in counterflow to the main flow direction of the hot gas flow in the mixer 12 after it passed through the third cooling channel 17. After at least partly cooling the mixer wall the cooling gas 33 is fed into the dilution gas inlet 19 and admixed to the hot gas in the mixer 12.

(23) The embodiment of FIG. 3 further differs from the embodiment of FIG. 1 in that first cooling channel 15 is not cooled in parallel flow but in counterflow.

(24) For cooling the first combustion chamber 11 compressed gas 8 is fed into the first cooling channel 15 as cooling gas 33 at an downstream end (relative to the hot gas flow direction) and flows in counterflow to the main flow direction of the hot gas flow in the first combustion chamber 11. After passing through the cooling channel 15 the cooling gas 33 is fed to the first burner 10.

(25) In this example only cooling gas 33 is fed to the first burner 10. Additional compressed gas 8 can be directly fed to the first burner (not shown).

(26) FIG. 4 shows a sequential combustion arrangement with serial cooling of the cooling zones and subsequent use of the cooling gas 33 as dilution gas 32 and subsequent use of cooling gas 33 in the first burner 10. In contrast to the example of FIG. 1 all four cooling channels 15, 16, 17, 18 are fluidly connected. Compressed gas 8 is fed into the fourth cooling channel 18 as cooling gas 33 at a downstream end (relative to the hot gas flow direction) and flows in counterflow to the main flow direction of the hot gas flow in the second combustion chamber 14. At least part of the cooling gas 33 flows through the fourth cooling channel 18, through the third cooling channel 17, through the second cooling channel 16 and through the first cooling channel 15 in series.

(27) After at least partly cooling the mixer wall part of the cooling gas 33 is fed into the dilution gas inlet 19 and admixed to the hot gas as dilution gas 32 in the mixer 12.

(28) After passing through the first cooling channel 15 the remaining cooling gas 33 is fed to the first burner 10.

(29) In this example only cooling gas 33 is fed to the first burner 10. Additional compressed gas 8 can be directly fed to the first burner (not shown).

(30) The embodiment of FIG. 5 differs from the embodiment of FIG. 1 in that the second cooling channel 16 is split into two sections. A first section is fluidly connected to the first cooling channel 15 and cooling gas 33 enters the second cooling channel for cooling the mixer wall from the first cooling channel 15. After at least partly cooling the mixer wall the cooling gas 33 is fed into a dilution gas inlet 19 and admixed to the hot gas as dilution gas 32 in the mixer 12.

(31) A second section of the second cooling channel 16 is fluidly connected to the third cooling channel 17 and cooling gas 33 enters the second cooling channel for cooling the mixer wall. After at least partly cooling the mixer the cooling gas 33 is fed into a dilution gas inlet 19 and admixed to the hot gas as dilution gas 32 in the mixer 12.

(32) The embodiment of FIG. 6 is based on FIG. 3. In this example the second cooling channel 16 does not extend along the full length of the mixer 12. At an upstream end the mixer is directly accessed by compressed gas 8. Compressed gas 8 is directly fed to an additional dilution gas inlet 19 and admixed to the hot gas as dilution gas 32 in the mixer 12.

(33) The embodiment of FIG. 7 is based on FIG. 1. In this example cooling gas 33 is fed to the first cooling channel 15 at a location between the upstream and downstream end of the first cooling channel 15. From the fed location part of the cooling gas 33 flows in counterflow to the main flow direction of the hot gas flow in the first combustion chamber 11. After passing through the first cooling channel 15 this cooling gas 33 is fed to the burner 10.

(34) The remaining cooling gas 33, which is fed into the first cooling channel 15 flows through the first cooling channel 15 parallel to the main flow direction of the hot gas flow in the first combustion chamber 11. After passing through the first cooling channel 15 the cooling gas 33 enters the second cooling channel 16 at an upstream end like in the example of FIG. 1.

(35) Further, FIG. 7 shows a sequential combustion arrangement in a can architecture and with a flame sheet burner. In this example compressed gas 8 is directly fed to the burner 10 in addition to cooling gas 33.

(36) The embodiment of FIG. 8 is based on FIG. 4. In this example the cooling scheme is unchanged but a sequential combustion arrangement in can architecture and with a flame sheet burner is shown.

(37) The embodiment of FIG. 9 is based on FIG. 3. In this example the cooling scheme is unchanged but a sequential combustion arrangement in can architecture and with a flame sheet burner is shown.

(38) For all shown arrangements can or annular architectures or any combination of the two is possible. EV, AEV or BEV burners can be used for can as well as for annular architectures.

(39) The mixing quality of the mixer 12 is crucial for a stable clean combustion since the burner system of the second combustion chamber 14 requires a prescribed inlet conditions.

(40) All the explained advantages are not limited to the specified combinations but can also be used in other combinations or alone without departing from the scope of the disclosure. Other possibilities are optionally conceivable, for example, for deactivating individual burners or groups of burners at part load operation. Further, the cooling gas and the dilution gas can be re-cooled in a cooling gas cooler before use as cooling gas, respectively as dilution gas.