Gas turbine combustion engine

Abstract

This gas turbine combustor is provided with: a plurality of swirling cylinders (31) that are arranged within a combustor liner (11) and that impart a swirling flow to a premixed gas (Fp) comprising fuel and combustion air mixed in advance; and an outer ring (15) arranged between the plurality of swirling cylinders (31) and the combustor liner (11) with a gap (41) between said outer ring (15) and the combustor liner (11), said outer ring (15) generating air (Af) in a film-like state within a combustor tail pipe (12) connected to the combustor liner (11) such that the air (Af) is jetted toward the combustor tail pipe (12) from the gap (41). The outer ring (15) comprises a tapered surface formed such that the thickness of the outer ring (15) on the downstream end (15d) thereof decreases gradually from the upstream side toward the downstream side.

Description

gas turbine combustor The present invention relates to a gas turbine combustor. In recent years, many combustors for gas turbines have adopted a premix combustion method for the purpose of reducing NOx, etc. A gas turbine combustor employing such a premix combustion method includes a pilot burner that performs diffusion combustion in addition to a main burner (premix burner) that performs premix combustion. This allows the main burner to use the diffusion flame generated by the pilot burner as a pilot flame to generate the premixed flame, and uses this diffusion flame to generate the premixed mixture generated by that main burner. By burning, premix combustion is possible. JP2014-92286A JP2005-315457A However, near the outlet of the main burner, the premix flows along the inner circumferential surface of the main burner, resulting in a region where the flow velocity decreases due to the development of a boundary layer. High fuel concentration areas may occur due to air. In this way, when a region with low speed and high fuel concentration occurs near the outlet of the main burner, the flame generated downstream of the region will burn out, causing a so-called flashback. (backfire) may occur. Therefore, various gas turbine combustors that can suppress the occurrence of flashback have been studied (see Patent Documents 1 and 2). For example, as shown in FIG. 4, in the gas turbine combustor 100, a plurality of swirler pipes 131 are provided on the radially outer side of the pilot cone 121 and provide a swirling flow to the premixture Fp, and a diameter of the plurality of swirler pipes 131 is The outer ring 115 is disposed on the outside in the direction and has a gap 141 between it and the combustor inner cylinder 111, and the compressed air taken in is injected from within the gap 141 so that the film-like air Af is combusted. It is configured to flow along the inner peripheral surface of the tail tube (or outlet outer ring) 112. This prevents flashback fb (wall surface) running up along the inner circumferential surface of the combustor transition piece 112, which is a low flow velocity region within the boundary layer. However, in the gas turbine combustor 100 described above, as shown in FIG. As the compressed air flows downstream along the inner circumferential surface 115b, the flow of compressed air separates from the outer circumferential surface 115c of the outer ring 115 and stagnation S1 occurs. Stagnation occurs due to separation from the peripheral surface 115b, and a low flow velocity region occurs at this location. Therefore, the area where stagnation occurs becomes a flame-holding area, and there is a possibility that flashback may occur. In view of the above, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to suppress the occurrence of flashback at the downstream end of the outer ring with a simple configuration. The objective is to provide a gas turbine combustor that can. The gas turbine combustor according to the first invention that solves the above-mentioned problems has the following features: A plurality of swirler tubes are arranged in the combustor inner cylinder and provide a swirling flow to the premixed mixture of fuel and combustion air, A gap is arranged between the plurality of swirler tubes and the combustor inner tube with respect to the combustor inner tube, and the fuel is injected from the gap toward the combustor transition tube connected to the combustor inner tube. and an outer ring that generates a film of air in the combustor transition piece. Equipped with The outer ring has a tapered surface formed at the downstream end of the outer ring so that the thickness gradually decreases from the upstream side to the downstream side. It is characterized by A gas turbine combustor according to a second invention that solves the above-mentioned problems is a gas turbine combustor according to the first invention described above, The tapered surface is formed on the inner peripheral surface side of the outer ring. It is characterized by A gas turbine combustor according to a third invention that solves the above-mentioned problems is a gas turbine combustor according to the first invention described above, The tapered surface is formed on both the inner circumferential surface side and the outer circumferential surface side of the outer ring. It is characterized by A gas turbine combustor according to a fourth invention that solves the above-mentioned problems is a gas turbine combustor according to the first invention described above, The tapered surface is formed on the outer peripheral surface side of the outer ring. It is characterized by A gas turbine combustor according to a fifth invention that solves the above-mentioned problems is a gas turbine combustor according to any one of the first to fourth inventions described above, The tapered surface has a curved shape in a cross section cut along the central axis of the outer ring. It is characterized by A gas turbine combustor according to a sixth invention that solves the above-mentioned problems is a gas turbine combustor according to any one of the first to fourth inventions described above, The tapered surface has an angle of 30 degrees to 60 degrees with respect to the radial direction. It is characterized by According to the present invention, the outer ring has a tapered surface formed at the downstream end of the outer ring so that the thickness gradually decreases from the upstream side to the downstream side, so that the premixture or compressed air is Flows smoothly downstream along the inner or outer circumferential surface of the ring, eliminating separation of the premixture or compressed air flow at the downstream end of the outer ring, and eliminating stagnation caused by separation of the gas flow. The area becomes smaller. This makes it possible to suppress the occurrence of flashback at the downstream end of the outer ring with a simple configuration. 1 is a diagram schematically showing the internal configuration of a gas turbine combustor according to a first embodiment of the present invention. FIG. 3 is a diagram schematically showing the internal configuration of a gas turbine combustor according to a second embodiment of the present invention. FIG. 3 is a diagram schematically showing the internal configuration of a gas turbine combustor according to a third embodiment of the present invention. FIG. 1 is a schematic diagram showing an example of a conventional gas turbine combustor. 5 is an enlarged view of the encircling line V in FIG. 4. FIG. Although embodiments of the gas turbine combustor according to the present invention will be described based on the drawings, the present invention is not limited only to the following embodiments described based on the drawings. [First embodiment] A gas turbine combustor according to a first embodiment of the present invention will be described using FIG. 1. In addition, in FIG. 1, the code|symbol C1 has shown the central axis of a combustor inner cylinder. As shown in FIG. 1, a gas turbine combustor 1 employs a premix combustion method, and includes a combustor inner cylinder 11 that mixes fuel F and compressed air A for combustion, and a combustor inner cylinder 11 that mixes fuel F and compressed air A for combustion. The combustor transition piece 12 is connected to the downstream end (rear end) of the cylinder 11 and serves as a combustion chamber. Furthermore, a pilot burner 13 and a plurality of main burners (premix burners) 14 are housed in the upstream end (front end) of the combustor inner cylinder 11 . The pilot burner 13 is arranged coaxially with the combustor inner cylinder 11 and is composed of a pilot cone 21, a pilot nozzle 22, and a pilot swirler 23. A pilot nozzle 22 is inserted into the pilot cone 21 so as to be coaxial with the pilot cone 21. A pilot swirler 23 is interposed between the inner peripheral surface of the pilot cone 21 and the outer peripheral surface of the pilot nozzle 22. The main burners 14 are provided on the radially outer side of the pilot burner 13 at equal angular intervals in the circumferential direction of the combustor inner cylinder 11, and are composed of a swirler tube 31, a main nozzle (premixing nozzle) 33, and a main swirler 34. ing. A main nozzle 33 is inserted into the swirler tube 31 so as to be coaxial with the swirler tube 31. A main swirler 34 is interposed between the inner peripheral surface of the swirler tube 31 and the outer peripheral surface of the main nozzle 33. The swirler cylinder 31 is supported on the inner circumferential surface of the combustor inner cylinder 11 via the substrate 35. The gas turbine combustor 1 described above has an outer side that is arranged coaxially with the combustor inner cylinder 11 with a gap 41 between the plurality of swirler pipes 31 and the combustor inner cylinder 11. It further includes a ring 15. The outer ring 15 is supported on the outer peripheral surface of a swirler tube 31 provided in each of the plurality of main burners 14 via a fixture such as welding. The outer ring 15 is provided on the inner peripheral surface (inner diameter portion) 15b side on the downstream side thereof, and has an inner peripheral surface side tapered surface 15ba whose thickness gradually decreases from the upstream side to the downstream side. That is, the outer ring 15 has an inner peripheral surface side tapered surface 15ba at the downstream end 15d of the outer ring 15. The downstream end of the inner circumferential tapered surface 15ba is connected to the downstream end 15a of the outer ring 15. Thereby, the premixture Fp guided downstream along the inner peripheral surface 15b of the outer ring 15 flows smoothly downstream at a high flow velocity by the inner peripheral surface side tapered surface 15ba. Next, each operation during operation of the gas turbine combustor 1 will be explained. During operation of the gas turbine combustor 1, high-temperature, high-pressure compressed air A flows into the upstream end of the combustor inner cylinder 11, and is then supplied into the pilot burner 13 and the main burner 14. Fuel F is supplied into these pilot nozzles 22 and main nozzles 33. Here, in the pilot burner 13, first, the supplied compressed air A is mixed with the fuel F injected from the pilot nozzle 22 by being swirled by the pilot swirler 23. Next, by igniting the fuel mixture mixed in this way, diffusive combustion is performed inside the pilot cone 21 and on the downstream side (inside the combustor transition piece 12). The combustion gas generated by the diffusive combustion is supplied to the turbine side inside the combustor transition piece 12. On the other hand, in the main burner 14, first, the supplied compressed air A is swirled by the main swirler 34 and mixed with the fuel F injected from the main nozzle 33, thereby generating a premixture Fp. Next, the swirled premixture Fp is guided downstream by the outer ring 15 and the pilot cone 21 and is supplied into the combustor transition pipe 12. At this time, the premixture Fp guided downstream along the inner circumferential surface 15b of the outer ring 15 smoothly flows downstream by the inner circumferential surface side tapered surface 15ba. Thereafter, the premixed mixture Fp supplied into the combustor transition pipe 12 is combusted by a diffusion flame generated by the pilot burner 13, and premixed combustion is performed. At this time, when the gas turbine combustor 1 is operating as described above, the compressed air A is also supplied around the main burner 14, so the compressed air A is always supplied to the combustor inner cylinder 11. It is taken into the combustor transition piece 12 through a gap (air passage) 41 between the inner circumferential surface 11a of the outer ring 15 and the outer circumferential surface 15c of the outer ring 15. That is, compressed air A is injected into the combustor transition piece 12 through the gap 41, thereby becoming film-like air (hereinafter referred to as film air) Af, and this film air Af is injected into the combustor transition piece 12. It flows toward the downstream side along the inner peripheral surface. Therefore, according to the gas turbine combustor 1 according to the present embodiment, the plurality of swirler tubes 31 and the combustor inner tube 11 are arranged with a gap 41 with respect to the combustor inner tube 11, and the gap 41 The outer ring 15 is provided with an outer ring 15 that injects film air Af toward the combustor transition piece 12 connected to the combustor inner cylinder 11 to generate film air Af in the combustor transition piece 12, and the outer ring 15 is provided with a By having an inner circumferential surface side tapered surface 15ba formed on the inner circumferential surface 15b side so that the thickness gradually decreases from the upstream side to the downstream side at the end 15d, the inner circumferential surface 15b of the outer ring 15 The premixed gas Fp guided to the downstream side flows smoothly from the upstream side to the downstream side at a high flow rate by the inner peripheral surface side tapered surface 15ba, and the premixing at the downstream end portion 15a of the outer ring 15 is completed. Separation of the flow of gas Fp is eliminated, and a stagnation area caused by separation of the gas flow is reduced. This suppresses the occurrence of flashback at the downstream end 15a of the outer ring 15 with a simple configuration. Further, since the premixture Fp is promoted to be mixed by the film air Af, a reduction in NOx can be expected. Therefore, combustion is stabilized and a decrease in combustion efficiency is suppressed. Further, it is preferable that the inner circumferential side tapered surface 15ba has an angle θ1 in a range of 30 degrees to 60 degrees with respect to the radial direction. This is because the premixture Fp guided downstream along the inner circumferential surface 15b of the outer ring 15 flows downstream more smoothly. [Second embodiment] A gas turbine combustor according to a second embodiment of the present invention will be described using FIG. 2. Note that in this embodiment, only the outer ring is changed, and other than that, the gas turbine combustor includes the same members as the gas turbine combustor according to the first embodiment described above. In this embodiment, the same members as those in the gas turbine combustor according to the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In FIG. 2, only the internal structure of the upper half of the gas turbine combustor is shown. As shown in FIG. 2, the gas turbine combustor 1A according to the present embodiment has a pilot burner 13 and It includes a main burner 14 and a combustor transition piece 12 connected to the combustor inner cylinder 11 , and the inner part of the combustor inner cylinder 11 is connected between the plurality of swirl tubes 31 of the main burner 14 and the combustor inner cylinder 11 . The outer ring 15A is arranged coaxially with the combustor inner cylinder 11 and has a gap 41 with respect to the peripheral surface 11a. Note that, like the outer ring 15, the outer ring 15A is supported on the outer circumferential surface of the swirler tube 31 provided in each of the plurality of main burners 14 via a fixture such as welding. On the downstream side, the outer ring 15A has an inner circumferential tapered surface 15Aba and an outer circumferential tapered surface 15Aca, which are formed so that the thickness gradually decreases from the upstream side to the downstream side. That is, the outer ring 15A has an inner circumferential side tapered surface 15Aba and an outer circumferential side tapered surface 15Aca at the downstream end 15Ad of the outer ring 15A. The inner peripheral surface side tapered surface 15Aba is formed on the inner peripheral surface (inner diameter portion) 15Ab side of the outer ring 15A. The outer peripheral surface side tapered surface 15Aca is formed on the outer peripheral surface (outer diameter portion) 15Ac side of the outer ring 15A. The inner peripheral surface side tapered surface 15Aba has a curved shape that projects toward the outer peripheral surface 15Ac. The outer peripheral surface side tapered surface 15Aca has a curved shape that projects toward the inner peripheral surface 15Ab side. That is, the inner peripheral surface side tapered surface 15Aba and the outer peripheral surface side tapered surface 15Aca have a curved shape in a cross section cut along the central axis of the outer ring 15A. Further, the downstream sides of the inner peripheral surface side tapered surface 15Aba and the outer peripheral surface side tapered surface 15Aca are connected to the downstream end 15Aa of the outer ring 15A. Thereby, the premixture Fp guided downstream along the inner circumferential surface 15Ab of the outer ring 15A flows smoothly downstream at a high flow velocity by the inner circumferential surface side tapered surface 15Aba. The compressed air A guided downstream along the outer circumferential surface 15Ac of the outer ring 15A flows smoothly downstream at a high flow rate due to the outer circumferential surface side tapered surface 15Aca. Therefore, according to the gas turbine combustor 1A according to the present embodiment, the plurality of swirler tubes 31 and the combustor inner tube 11 are arranged with a gap 41 with respect to the combustor inner tube 11, and the gap 41 The outer ring 15A is provided with an outer ring 15A that injects film air Af into the combustor transition piece 12 connected to the combustor inner cylinder 11 from the outer ring 15A. An inner circumferential surface side tapered surface 15Aba and an outer circumferential surface side tapered surface 15Aca are formed on the inner circumferential surface 15Ab side and the outer circumferential surface 15Ac side, respectively, so that the thickness gradually decreases from the upstream side to the downstream side at the downstream end 15Ad. By having this, the premixture Fp guided to the downstream side along the inner peripheral surface 15Ab of the outer ring 15A flows smoothly at a high flow rate from the upstream side to the downstream side by the inner peripheral surface side tapered surface 15Aba. On the other hand, the compressed air A guided downstream along the outer peripheral surface 15Ac of the outer ring 15A flows smoothly at a high flow rate from the upstream side to the downstream side due to the outer peripheral surface side tapered surface 15Aca. This eliminates the separation of the flow of the premixed air Fp and the flow of the compressed air A at the downstream end 15Aa of the outer ring 15A, and reduces the stagnation area caused by separation of the gas flow. As a result, the occurrence of flashback at the downstream end 15Aa of the outer ring 15A is suppressed with a simple configuration. Since the premixture Fp is promoted to be mixed by the film air Af, a reduction in NOx can be expected. Furthermore, since there is no outward flow of the premixer Fp, it is difficult for the premixer Fp to flow to the inner wall of the combustor transition piece 12, and it is expected that flashback occurring in the wall boundary layer will be suppressed. Therefore, combustion is stabilized and a decrease in combustion efficiency is suppressed. In addition, since the inner circumferential side tapered surface 15Aba and the outer circumferential side tapered surface 15Aca have a curved shape in a cross section cut along the central axis of the outer ring 15A, these points are aligned with the central axis of the outer ring 15A. Compared to the case where the cross section cut along the line is a straight line, the premixed air Fp and the compressed air A flow more smoothly. As a result, the stagnation area that occurs at the downstream end 15Aa of the outer ring 15A due to separation of the gas flow is smaller than when the tapered surface is a straight line in a cross section taken along the central axis of the outer ring 15A. become smaller. As a result, the occurrence of flashback at the downstream end 15Aa of the outer ring 15A is further suppressed with a simple configuration. Therefore, combustion becomes more stable, and a decrease in combustion efficiency is further suppressed. [Third embodiment] A gas turbine combustor according to a third embodiment of the present invention will be described using FIG. 3. Note that in this embodiment, only the outer ring is changed, and other than that, the gas turbine combustor includes the same members as the gas turbine combustor according to the first embodiment described above. In this embodiment, the same members as those in the gas turbine combustor according to the first embodiment described above are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. FIG. 3 shows only the internal structure of the upper half of the gas turbine combustor. As shown in FIG. 3, the gas turbine combustor 1B according to the present embodiment has a pilot burner 13 and It includes a main burner 14 and a combustor transition piece 12 connected to the combustor inner cylinder 11 , and the inner part of the combustor inner cylinder 11 is connected between the plurality of swirl tubes 31 of the main burner 14 and the combustor inner cylinder 11 . The outer ring 15B is provided coaxially with the combustor inner cylinder 11 and has a gap 41 with respect to the peripheral surface 11a. Note that, like the outer ring 15, the outer ring 15B is supported on the outer circumferential surface of the swirl tube 31 provided in each of the plurality of main burners 14 via a fixture such as welding. The outer ring 15B has an outer circumferential tapered surface 15Bca formed on its downstream side so that its thickness gradually decreases from the upstream side to the downstream side. That is, the outer ring 15B has an outer peripheral tapered surface 15Bca at the downstream end 15Bd of the outer ring 15B. The outer peripheral surface side tapered surface 15Bca is formed on the outer peripheral surface (outer diameter portion) 15Bc side of the outer ring 15B. Further, the downstream side of the outer circumferential tapered surface 15Bca is connected to the downstream end 15Ba of the outer ring 15B. Thereby, the compressed air A guided downstream along the outer circumferential surface 15Bc of the outer ring 15B flows smoothly downstream at a high flow velocity by the outer circumferential surface side tapered surface 15Bca. Note that the premixture Fp guided downstream along the inner circumferential surface 15Bb of the outer ring 15B is supplied into the combustor transition piece 12 as it is. Therefore, according to the gas turbine combustor 1B according to the present embodiment, the plurality of swirler tubes 31 and the combustor inner tube 11 are arranged with a gap 41 with respect to the combustor inner tube 11, and the gap 41 The outer ring 15B is provided with an outer ring 15B that injects film air Af toward the combustor transition piece 12 connected to the combustor inner cylinder 11 to generate film air Af in the combustor transition piece 12. By having an outer circumferential surface-side tapered surface 15Bca formed on the outer circumferential surface 15Bc side so that the thickness gradually decreases from the upstream side toward the downstream side at the downstream end 15Bd, the outer circumferential surface 15Bc of the outer ring 15B is formed on the downstream side along the outer circumferential surface 15Bc. The compressed air A guided by the outer peripheral surface side taper surface 15Bca flows smoothly from the upstream side to the downstream side at a high flow rate. This eliminates separation of the flow of compressed air A at the downstream end 15Ba of the outer ring 15B, and reduces the stagnation area caused by separation of the gas flow. As a result, the occurrence of flashback at the downstream end 15Ba of the outer ring 15B is suppressed with a simple configuration. Since there is no outward flow of the premixture Fp and film air Af with little fuel mixture flows on the inner wall of the combustor transition piece 12, it can be expected that flashback occurring in the wall boundary layer will be suppressed. Therefore, combustion is stabilized and a decrease in combustion efficiency is suppressed. Further, it is preferable that the outer peripheral surface side tapered surface 15Bca has an angle θ3 in a range of 30 degrees to 60 degrees with respect to the radial direction. This is because the compressed air A guided downstream along the outer peripheral surface 15Bc of the outer ring 15B flows downstream more smoothly. [Other embodiments] The above-described gas turbine combustor 1A is applied to the gas turbine combustor 1, 1B according to the above-described first and third embodiments so that the inner circumferential side tapered surface, the outer circumferential side tapered surface, or both thereof have a curved shape. It is also possible to use a gas turbine combustor with Even with such a gas turbine combustor, the same effects as the above-mentioned gas turbine combustor 1A are achieved. It is also possible to combine the gas turbine combustors 1 and 1B described above to form a gas turbine combustor that includes an outer ring in which an inner circumferential surface and an outer circumferential surface are respectively formed with a tapered surface on the inner circumferential side and a tapered surface on the outer circumferential side. It is. Even with such a gas turbine combustor, the same effects as the above-mentioned gas turbine combustors 1 and 1B are achieved. The above-described gas turbine combustors 1, 1A, and 1B are applied to a gas turbine combustor that includes an outer ring in which the downstream end extends downstream from the downstream end of the pilot cone in the gas flow direction. It is also possible. Even with such a gas turbine combustor, the same effects as the above-mentioned gas turbine combustors 1, 1A, and 1B are achieved. The above-mentioned gas turbine combustors 1, 1A, and 1B are combined with a gas turbine combustor in which each of the swirler tubes 31 of the plurality of main burners 14 is provided with an extension tube, an outer ring, and a combustor inner tube (combustor tail tube). It is also possible to apply it to gas turbine combustors with an outlet outer ring arranged between them. Even with such a gas turbine combustor, the same effects as the above-mentioned gas turbine combustors 1, 1A, and 1B are achieved. The gas turbine combustor according to the present invention has a simple configuration and can suppress the occurrence of flashback at the downstream end of the outer ring, so it can be used to great advantage industrially. 1, 1A, 1B Gas turbine combustor 11 Combustor inner cylinder 12 Combustor transition piece 13 Pilot burner 14 Main burner 15, 15A, 15B outer ring 15a, 15Aa, 15Ba downstream end 15b, 15Ab, 15Bb inner peripheral surface 15ba, 15Aba Inner peripheral side tapered surface 15c, 15Ac, 15Bc outer peripheral surface 15Aca, 15Bca Outer peripheral side tapered surface 15d, 15Ad, 15Bd downstream end 21 Pilot cone 22 Pilot nozzle 23 Pilot Swara 31 Swirler tube 33 Main nozzle 34 Main swirler 35 Board 41 Gap (air flow path) A Compressed air Af film air C1 Central axis of combustor inner cylinder C2 Center axis of combustor inner cylinder F Fuel Fp premixture θ1 Angle of inner peripheral surface side taper surface θ3 Angle of outer circumference side tapered surface

Claims

Page 1 of 1 page Claims 1. A gas turbine combustor characterized by the following: a number of swirl tubes arranged inside the combustion basket and causing the gas mixture to swirl, the gas mixture obtained by mixing the fuel with the air for combustion; and an outer ring arranged between a number of swirl tubes and the combustion basket with a gap provided between the outer ring and the combustion basket, and creating an air film inside the combustion transition element which is connected to the combustion basket by injection through the gap into the combustion transition element, and at the distal end of the outer ring, the outer ring includes a tapering surface formed in such a way that the outer ring gradually decreases in thickness from the distal end to the distal end.

2. A gas turbine combustor according to claim 1 characterized by the presence of a tapering surface formed on the inner perpendicular surface of the outer ring. 3.

1. A gas turbine combustor under claim 1 which is characterized by the formation of a constricting surface on both the inner and outer periphery of the outer ring.

2. A gas turbine combustor under claim 1 which is characterized by the formation of a constricting surface on the outer periphery of the outer ring.

3. A gas turbine combustor under claim 1 which is characterized by the formation of a constricting surface in cross-section of this section which intersects the central axis of the outer ring.

4. Any one of the gas turbine combustors under claims 1 through 4 which is characterized by the formation of a constricting surface at an angle of 30 to 60 degrees relative to the radial direction.