Combustor and gas turbine

Abstract

This combustor comprises a nozzle which extends along an axis and which injects fuel, and a burner cylinder into which the nozzle is inserted and in which air introduced from an upstream side is mixed with the fuel to generate a premixed gas, wherein the burner cylinder has a first inner peripheral surface on the upstream side and a second inner peripheral surface having a larger diameter than that of the first inner peripheral surface, on the downstream side of the first inner peripheral surface, and the burner cylinder additionally comprises: a first film supply portion which is formed between the first inner peripheral surface and the second inner peripheral surface, and which ejects first film air to the downstream side along the second inner peripheral surface; and a second film supply portion which is formed on the first inner peripheral surface and which ejects second film air inward in the radial direction of the axis, and toward the downstream side.

Description

Combustors and Gas Turbines

[0001] This application claims priority to Japanese Patent Application No. 2023-219092, filed on December 26, 2023, the contents of which are incorporated herein by reference.

[0002] Near the outlet of a premix burner that performs premixed combustion, the premixed gas flows along the inner circumferential surface, and the flow velocity may decrease partially due to the development of a boundary layer. This decrease in flow velocity may result in a high-fuel-concentration region, which may then be subject to flashback, where the flame spreads to the high-fuel-concentration region.

[0003] As a technique for suppressing this flashback, for example, Patent Document 1 discloses a technique for supplying film air along the inner circumferential surface of a burner tube that constitutes a premix burner. Specifically, the burner tube of a premix burner is composed of a burner tube body and an extension tube that is fitted to the outer circumferential surface of the burner tube body and extends downstream of the burner tube body. Air from the outer circumferential side of the premix burner is supplied as film air from a step between the inner circumferential surface of the burner tube body and the inner circumferential surface of the extension tube along the inner circumferential surface of the extension tube. This eliminates a high-fuel concentration region and suppresses the occurrence of flashback.

[0004] Patent No. 5893879

[0005] Even if the technology of Patent Document 1 is adopted, temporary flashback may occur if an abnormality such as rotating stall occurs in the compressor that supplies air. This flashback may cause the flame to be maintained at the tip (film lip) of the burner tube body, which is in a low flow velocity region.

[0006] The present disclosure provides a combustor and a gas turbine that can improve flashback resistance.

[0007] A combustor according to the present disclosure comprises: a nozzle extending along an axis and injecting fuel; and a burner tube into which the nozzle is inserted and into which the fuel is mixed with air introduced from the upstream side to generate premixed gas, wherein the burner tube has a first inner circumferential surface on the upstream side and a second inner circumferential surface that is on the downstream side of the first inner circumferential surface and has a larger diameter than the first inner circumferential surface and extends further downstream, and further comprises: a first film supply portion formed between the first inner circumferential surface and the second inner circumferential surface and ejects first film air downstream along the second inner circumferential surface; and a second film supply portion formed on the first inner circumferential surface and ejects second film air radially inward in the axis and downstream.

[0008] The gas turbine according to the present disclosure includes the above-described combustor that generates combustion gas by mixing the fuel with the air and burning the mixture, a compressor that supplies the compressed air to the combustor, and a turbine that is driven by the combustion gas generated by the combustor.

[0009] According to the present disclosure, flashback resistance can be improved.

[0010] FIG. 1 is a schematic overall configuration diagram of a gas turbine according to a first embodiment of the present disclosure. FIG. 2 is a schematic longitudinal sectional view of a combustor according to the first embodiment of the present disclosure. FIG. 3 is a partial enlarged view of FIG. 4 is an enlarged view of a main portion of FIG. 4. FIG. 5 is an enlarged view of a main portion in the schematic longitudinal sectional view of a combustor according to a second embodiment of the present disclosure. FIG. 6 is an enlarged view of a main portion in the schematic longitudinal sectional view of a combustor according to a third embodiment of the present disclosure. FIG. 7 is an enlarged view of a main portion in the schematic longitudinal sectional view of a combustor according to a fourth embodiment of the present disclosure. FIG. 8 is an enlarged view of a main portion in the schematic longitudinal sectional view of a combustor according to a fifth embodiment of the present disclosure. FIG. 9 is a longitudinal sectional view (upper view) and a circumferential projection view (lower view) illustrating air ejection holes of a combustor according to a sixth embodiment of the present disclosure. FIG. 10 is a longitudinal sectional view (upper view) and a circumferential projection view (lower view) illustrating air ejection holes of a combustor according to a modified example of the sixth embodiment of the present disclosure.

[0011] First Embodiment Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0012] A first embodiment of the present invention will be described in detail below with reference to Figures 1 to 4. As shown in Figure 1, a gas turbine 1 according to this embodiment includes a compressor 2 that compresses air A, a combustor 3 that generates combustion gas, and a turbine 4 that is driven by the combustion gas. A plurality of combustors 3 are provided at intervals in the circumferential direction around the rotation shaft of the gas turbine 1. The combustor 3 mixes fuel with the air A compressed by the compressor 2 and combusts the mixture to generate high-temperature, high-pressure combustion gas.

[0013] <Combustor> The configuration of the combustor 3 will be described below with reference to Figures 2 to 4. As shown in Figure 2, the combustor 3 has an outer cylinder 10, an end cover 11, an inner cylinder 15, a combustion cylinder 17, a base plate 19, a pilot burner 20, and a main burner 30.

[0014] <Outer Cylinder> The outer casing 10 has a cylindrical shape centered on a first axis O1 which is the center of the combustor 3. The outer casing 10 is attached to a casing of the gas turbine 1.

[0015] <End Cover> The end cover 11 closes one end (the left side in FIG. 2 ) of the outer casing 10 in the direction of the first axis O1 (hereinafter simply referred to as the axial direction). The end cover 11 is provided with a pilot fuel port 12 for introducing fuel to the pilot burner 20 and a main fuel port 13 for introducing fuel to the main burner 30. For example, natural gas or hydrogen is used as the fuel. A mixed fuel of natural gas and hydrogen may also be used as the fuel.

[0016] <Inner Cylinder> The inner cylinder 15 is coaxially disposed inside the outer cylinder 10. The inner cylinder 15 has a cylindrical shape extending in the axial direction inside the outer cylinder 10. The inner cylinder 15 extends further toward the other axial side (the right side in FIG. 2 ) than the outer cylinder 10. One axial end of the inner cylinder 15 is spaced apart from the end cover 11 in the axial direction. The outer diameter of the inner cylinder 15 is smaller than the inner diameter of the outer cylinder 10. As a result, an annular flow path is formed between the outer peripheral surface of the inner cylinder 15 and the inner peripheral surface of the outer cylinder 10. Air A compressed by the compressor 2 flows through this flow path from the other axial side toward the one axial side.

[0017] The inner cylinder 15 is supported by the outer cylinder 10 via struts 16. The struts 16 are members extending radially about the first axis O1, and a plurality of struts 16 are provided at intervals in the circumferential direction. The radially outer ends of the struts 16 are fixed to the inner circumferential surface of the outer cylinder 10. The radially inner ends of the struts 16 are fixed to the outer circumferential surface of the inner cylinder 15. Air A flowing in one axial direction between the outer cylinder 10 and the inner cylinder 15 passes between adjacent struts 16, then moves radially inward, and its flow direction is reversed to the other axial direction. Hereinafter, the downstream side (right side in FIG. 2 ) of the flow direction of the air A after this reversal will be simply referred to as the "downstream side," and the upstream side (left side in FIG. 2 ) of the flow direction of the air A after the reversal will be simply referred to as the "upstream side." The space inside the inner cylinder 15 is an air passage 100 through which air A flows from the downstream side to the upstream side (from one side to the other side in the axial direction).

[0018] <Combustion liner> The combustion liner 17 is a cylindrical member. The upstream portion of the combustion liner 17 has a cylindrical shape centered on the first axis O1, and is provided so as to cover the downstream tip of the inner liner 15 from the outer periphery. The downstream end of the combustion liner 17 is connected to the turbine 4. The combustion gas generated in the combustor 3 flows through a flow path inside the combustion liner 17 and is guided to the turbine 4.

[0019] The combustion cylinder 17 is connected to the inner cylinder 15 via a leaf spring seal 18. The leaf spring seal 18 is provided between the inner peripheral surface of the combustion cylinder 17 and the outer peripheral surface of the inner cylinder 15. The leaf spring seal 18 seals the entire circumferential area while biasing the inner peripheral surface of the combustion cylinder 17 and the outer peripheral surface of the inner cylinder 15 to separate them.

[0020] <Substrate> The substrate 19 is disk-shaped and extends along a plane perpendicular to the first axis O1, with the first axis O1 as its center. The substrate 19 has an outer peripheral edge portion fixed to the inner peripheral surface of the inner cylinder 15 over the entire circumference. The substrate 19 is provided at an axial position on the inner cylinder 15 where it overlaps with the outer cylinder 10. The substrate 19 has a plurality of holes formed therein, through which the pilot burner 20 and the main burner 30 pass in the axial direction.

[0021] <Pilot Burner> The pilot burner 20 is a burner provided along the first axis O1 inside the inner cylinder 15. The pilot burner 20 has a pilot nozzle 22, a pilot swirler 21, and a pilot burner cylinder 23.

[0022] The pilot burner 20 has a rod shape extending along the first axis O1, and its upstream end is fixed to the end cover 11. Fuel is introduced into the pilot burner 20 from its downstream end via a pilot fuel port 12. The fuel is ejected from near the tip of the pilot burner 20 located inside the inner cylinder 15.

[0023] A plurality of pilot swirlers 21 are provided at intervals in the circumferential direction of the first axis O1 on the outer peripheral surface of the pilot burner 20. The pilot swirlers 21 are provided so as to twist around the first axis O1 as they move from the downstream side to the upstream side.

[0024] The pilot burner tube 23 has a cylindrical portion 24 and a pilot cone 25. The cylindrical portion 24 has a cylindrical shape centered on the first axis O1 and is provided so as to surround the multiple pilot swirlers 21 and the pilot nozzle 22 from the outer periphery. The outer periphery ends of the multiple pilot swirlers 21 are connected to the inner circumferential surface of the pilot burner 20. The pilot cone 25 is connected to the downstream end of the cylindrical portion 24 and extends downstream beyond the tip of the pilot nozzle 22. The pilot cone 25 has a cylindrical shape centered on the first axis O1 and is tapered so that its diameter increases toward the downstream side. The pilot cone 25 is fixed to the substrate 19 so as to penetrate the substrate 19 in the axial direction.

[0025] <Main Burner> A plurality of main burners 30 are provided inside the inner cylinder 15 so as to surround the main burner 30. A plurality of main burners 30 are provided inside the inner cylinder 15, spaced apart in the circumferential direction, at positions radially outward of the first axis O1. The main burners 30 are provided along a second axis O2 that is parallel to the first axis O1. Therefore, the direction along the second axis O2 is also the axial direction. The main burner 30 has a main nozzle 31, a main swirler 32, and a main burner cylinder 40 (burner cylinder).

[0026] The main burner 30 has a rod shape extending along the second axis O2, and its upstream end is fixed to the end cover 11. Fuel is introduced into the main burner 30 from its downstream end via a main fuel port 13. The fuel is ejected from near the tip of the main burner 30 located inside the inner cylinder 15.

[0027] A plurality of main swirlers 32 are provided at intervals in the circumferential direction of the second axis O2 on the outer circumferential surface of the main burner 30. The main swirlers 32 are provided so as to twist around the second axis O2 as they move from the downstream side to the upstream side.

[0028] <Main burner cylinder (burner cylinder)> The main burner cylinder 40 is provided to surround the tip side portion of the main burner 30. The space inside the main burner cylinder 40 is used as a premixing space 110. The main burner 30 has a burner cylinder body 50 and an extension tube 60.

[0029] <Burner cylinder body> As shown in Fig. 3, the burner cylinder body 50 has a cylindrical shape centered on the second axis O2. The burner cylinder body 50 is provided coaxially with the main nozzle 31 so as to surround the main nozzle 31 and the main swirler 32 from the outer periphery. As shown in Fig. 3, the burner cylinder body 50 has, from the downstream side to the upstream side, a large diameter portion 50a, a reduced diameter portion 50b, and a small diameter portion 50c.

[0030] The large diameter section 50a is the large diameter portion located most upstream in the burner tube body 50, and its inner circumferential surface is connected to the outer circumferential ends of the multiple main swirlers 32. The inner diameter of the large diameter section 50a is uniform along the axial direction. The reduced diameter section 50b is connected to the downstream end of the large diameter section 50a so as to be continuous with it, and its diameter decreases as it extends downstream. The small diameter section 50c is connected to the downstream end of the reduced diameter section 50b so as to be continuous with it, and extends downstream beyond the tip of the main nozzle 31.

[0031] 2 and 3 , the upstream portion of the outer peripheral surface of the small diameter portion 50c is an upstream outer peripheral surface 51 whose upstream end is connected to the reduced diameter portion 50b. The upstream outer peripheral surface 51 has a uniform outer diameter in the axial direction. The downstream portion of the outer peripheral surface of the small diameter portion 50c is a downstream outer peripheral surface 52 whose diameter is one step smaller than that of the upstream outer peripheral surface 51. The downstream outer peripheral surface 52 also has a uniform outer diameter in the axial direction. The upstream outer peripheral surface 51 and the downstream outer peripheral surface 52 are connected by a stepped surface 53 that forms an annular shape centered on the second axis O2 and faces downstream.

[0032] The inner peripheral surface of the small diameter portion 50c is a first inner peripheral surface 54 having a uniform inner diameter in the axial direction. The portion between the downstream end of the first inner peripheral surface 54 and the downstream end of the downstream outer peripheral surface 52 is a film lip 55 that faces downstream and forms an annular shape centered on the second axis O2.

[0033] <Extension Pipe> The upstream portion of the extension pipe 60 has a cylindrical shape centered on the second axis O2. The downstream portion of the extension pipe 60 has a shape that transitions from the cylindrical portion to an arc-rectangular shape with the longitudinal direction aligned with the circumferential direction of the first axis O1 as it moves downstream. The outer peripheral surface of the extension pipe 60 is defined as an extended outer peripheral surface 61. The inner peripheral surface of the extension pipe 60 is defined as a second inner peripheral surface 62. In the upstream portion of the extension pipe 60, the second inner peripheral surface 62 has a uniform inner diameter centered on the second axis O2.

[0034] The upstream portion of the second inner peripheral surface 62 of the extension pipe 60 is fitted from the outer peripheral side over the entire circumference onto the upstream outer peripheral surface 51 of the small diameter portion 50c of the burner cylinder main body 50. This allows the burner cylinder main body 50 and the extension pipe 60 to be integrally connected. The boundary between the upstream portion and the downstream portion of the extension pipe 60 is located downstream of the tip of the burner cylinder main body 50.

[0035] An annular space 90 is defined between the downstream outer peripheral surface 52 of the small diameter portion 50c of the burner tube body 50 and the second inner peripheral surface 62 of the extension tube 60, and extends in the axial direction with the second axis O2 as its center. The downstream end of the annular space 90 is a first opening 71 that opens into a radially outer portion of the film lip 55. The inner peripheral edge of the first opening 71 is defined by the outer peripheral edge of the film lip 55. The outer peripheral edge of the first opening 71 is defined by the first inner peripheral surface 54. The first opening 71 is formed along a plane perpendicular to the second axis O2.

[0036] In a portion of the extension tube 60 upstream of the film lip 55 of the burner tube body 50, air inlet holes 63 are formed that penetrate radially and thereby connect the air passage 100 outside the extension tube 60 to the annular space 90. A plurality of air inlet holes 63 are provided spaced apart in the circumferential direction of the second axis O2. The upstream end of the air inlet hole 63 is located at the same axial position as the stepped surface 53 of the small diameter portion 50c of the burner tube body 50. The downstream end of the air inlet hole 63 is located upstream of the film lip 55. As a result, the upstream portion of the annular space 90 faces the air passage 100 via the air inlet holes 63.

[0037] With such a burner cylinder body 50 and extension pipe 60, the main burner cylinder 40 has a configuration including a first inner circumferential surface 54 and a second inner circumferential surface 62 that expands in diameter on the downstream side of the first inner circumferential surface 54 and extends further downstream. A film lip 55 is located in the step between the first inner circumferential surface 54 and the second inner circumferential surface 62.

[0038] <First Film Supply Section> The first film supply section 70 ejects first film air downstream along the second inner circumferential surface 62. The first film supply section 70 is configured by an annular first opening 71 that forms the downstream end of the annular space 90. That is, the first film supply section 70 is configured by the first opening 71 that is centered on the second axis O2 and is formed in the step between the first inner circumferential surface 54 and the second inner circumferential surface 62.

[0039] <Second Film Supply Section> The second film supply section 80 ejects second film air downstream along the first inner circumferential surface 54. The second film supply section 80 is configured by second openings 81 of a plurality of air ejection holes 82.

[0040] That is, the burner cylinder body 50 of the main burner cylinder 40 is formed with air ejection holes 82 that penetrate the burner cylinder body 50 in the radial direction. The air ejection holes 82 open to the downstream outer peripheral surface 52 and the first inner peripheral surface 54 of the small diameter portion 50c of the burner cylinder body 50. The air ejection holes 82 are inclined downstream as they extend radially inward about the second axis O2. The opening of the air ejection hole 82 on the first inner peripheral surface 54 is located more downstream than the opening on the downstream outer peripheral surface 52. The air ejection holes 82 form a hole group that is arranged at intervals in the circumferential direction of the second axis O2. The axial positions of each air ejection hole 82 in the hole group are the same. The opening of the air ejection hole 82 on the first inner peripheral surface 54 is the second opening 81.

[0041] In this embodiment, the radially outer end of the air ejection holes 82 of the hole group, i.e., the opening to the downstream outer peripheral surface 52, is located within the range of the axial position of the air introduction holes 63 in the annular space 90. The second opening 81, which is the radially inner end of the air ejection holes 82 of the hole group, is located at the axial position of the air introduction holes 63.

[0042] <Operation and Effect> In the combustor 3 configured as described above, when high-temperature, high-pressure air A flows into the air passage 100 inside the inner cylinder 15, it is guided to the pilot burner cylinder 23 of the pilot burner 20 and the main burner cylinder 40 of the main burner 30. The air A guided to the main burner 30 becomes a swirling airflow by the main swirler 32 inside the main burner cylinder 40, and is mixed with fuel injected from the main nozzle 31 to become premixed gas. The premixed gas then passes through the extension tube 60 and flows into the combustion cylinder 17.

[0043] The air A guided to the pilot burner 20 becomes a swirling air current in the pilot burner tube 23 by the pilot swirler 21, mixes with fuel injected from the pilot nozzle 22, and is ignited and combusted by a pilot flame (not shown). The combustion gas thus generated passes through the pilot cone 25 and is ejected into the combustion tube 17. At this time, part of the combustion gas is ejected into the combustion tube 17 with a flame so as to diffuse to the surroundings, and the premixed gas that has flowed into the combustion tube 17 from each main burner 30 is ignited and combusted.

[0044] In this way, the diffusion flame of the fuel injected from the pilot burner 20 can maintain flame stability for stable combustion of the premixed gas from the main burner 30. The region where the premixed gas is burned by the diffusion flame from the pilot burner 20 becomes the combustion region 120.

[0045] In the combustor 3, when a boundary layer of the premixed gas flow develops on the inner surface of the main burner tube 40, the flow velocity is partially reduced, forming a high fuel concentration region.Flashback may occur when the flame in the combustion region 120 spreads to such a high fuel concentration region.

[0046] In contrast, in this embodiment, the first film supply unit 70 can supply first film air along the inner circumferential surface of the main burner cylinder 40. That is, as shown in Fig. 4, air A in the air passage 100 on the outer circumferential side of the main burner cylinder 40 enters the annular space 90 from the air A inlet. The air A then flows downstream through the annular space 90 and is ejected from the first film supply unit 70 through the first opening 71 along the second inner circumferential surface 62. This makes it possible to eliminate a high fuel concentration region near the second inner circumferential surface 62 and suppress the occurrence of flashback.

[0047] If an abnormality such as a rotating stall occurs in the compressor 2 of the gas turbine 1, a temporary flashback may occur. This flashback may cause a flame to be held at the film lip 55, which is the step between the first inner circumferential surface 54 and the second inner circumferential surface 62. That is, the area around the film lip 55 formed to constitute the first film supply section 70 is a low-flow-velocity region within the premixing space 110. Furthermore, first film air cannot be supplied to this area.

[0048] In contrast, in this embodiment, flame stabilization at the film lip 55 can be suppressed by the second film air supplied from the second film supply unit 80 to the inner circumferential surface of the burner tube body 50. That is, as shown in FIG. 4 , air A introduced into the air inlet hole 63 flows through the annular space 90 and also enters each air ejection hole 82 facing the air inlet hole 63. The air then flows through the air ejection holes 82 obliquely toward the radially inward and downstream side and is ejected from the second openings 81 formed in the first inner circumferential surface 54. The ejected air A flows as second film air, which flows along the first inner circumferential surface 54. The second film air reaches the film lip 55, thereby preventing a high-fuel-concentration region from being formed at the film lip 55. This more effectively suppresses flashback throughout the combustor 3.

[0049] Furthermore, even if flame stabilization temporarily occurs at the film lip 55, the flame stabilization is quickly eliminated by the second film air after the compressor 2 recovers from the abnormality. Therefore, the purge-out performance of the combustor 3 can be improved.

[0050] In particular, in this embodiment, the inlets of the air ejection holes 82, which serve as the supply source of the second film air, are formed at the same axial position as the air introduction holes 63. In other words, the inlets of the air ejection holes 82 face the air passage 100 via the air introduction holes 63. This promotes the introduction of air A into the air ejection holes 82. This ensures an appropriate flow rate of the second film air.

[0051] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 5. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The combustor 3 of the second embodiment differs from the first embodiment in the configuration of the second film supply section 80.

[0052] That is, in the second embodiment, the multiple air ejection holes 82 are arranged alternately on the upstream and downstream sides as they move circumferentially, and the radially outer end of each air ejection hole 82 is located in the axial position of the air introduction hole 63, as in the first embodiment.

[0053] This allows the second openings 81 to be arranged at a high density while maintaining the structural strength of the burner tube body 50, thereby more appropriately ensuring the flow rate of the second film air.

[0054] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 6. In the third embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The combustor 3 of the third embodiment differs from the other embodiments in the configuration of the second film supply section 80.

[0055] That is, in the third embodiment, the air ejection holes 82 have the same arrangement structure as in the second embodiment, but are arranged in a different location. The air ejection holes 82 in the third embodiment are provided closer to the tip of the burner tube body 50 than in the second embodiment. The radially outer end of each air ejection hole 82 is located downstream of the air introduction hole 63. Therefore, the inlet opening of each air ejection hole 82 does not face the air passage 100 via the air introduction hole 63.

[0056] As a result, the air A introduced into the annular space 90 through the air inlet hole 63 flows through the narrow space between the burner tube body 50 and the extension tube 60, and some of it is ejected from the first opening 71 to become first film air, while the rest is introduced into the air ejection hole 82 and ejected from the second opening 81 to become second film air.

[0057] This allows the second film air to be supplied from closer to the film lip 55, where flame stabilization is likely to occur in the event of an abnormality. Therefore, flame stabilization at the film lip 55 can be further suppressed, and even if flame stabilization occurs at the film lip 55, the flame stabilization can be quickly eliminated.

[0058] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 7. In the fourth embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The combustor 3 of the fourth embodiment differs from the other embodiments in the configuration of the second film supply section 80.

[0059] That is, the fourth embodiment is a combination of the second and third embodiments, and the air ejection holes 82 constituting the second film supply section 80 have a first group of holes arranged on the upstream side and a second group of holes arranged on the downstream side. The second group of holes has the same configuration as in the second embodiment. The third group of holes has the same configuration as in the third embodiment.

[0060] As a result, similar to the second embodiment, the second film air can be supplied from a location closer to the film lip 55 where flame stabilization is likely to occur while an appropriate flow rate of the second film air is ensured. Therefore, it is possible to further suppress or eliminate flashback at the film lip 55.

[0061] In the third and fourth embodiments, the arrangement of each hole group is the same as in the second embodiment, but the axial positions of the air ejection holes 82 that make up each hole group may be the same, as in the first embodiment.

[0062] Fifth Embodiment Next, a fifth embodiment of the present disclosure will be described with reference to Fig. 8. In the fifth embodiment, the same components as those in the other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. In the combustor 3 of the fifth embodiment, the air ejection holes 82 constituting the second film supply section 80 are slit-shaped.

[0063] That is, the air ejection holes 82 in the fifth embodiment are slit-shaped and extend in the circumferential direction. A plurality of such slit-shaped air ejection holes 82 are formed at intervals in the circumferential direction. This makes it possible to ensure the same film effect with a smaller film air volume than in the other embodiments. Therefore, it is possible to effectively suppress flashback while maintaining the performance of the combustor 3.

[0064] The slit-shaped air ejection holes 82 may be arranged and positioned as in the second to fourth embodiments.

[0065] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described with reference to FIG. 9. In the sixth embodiment, the same components as those in the other embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. In the sixth embodiment, the configuration of each air ejection hole 82 constituting the second film supply unit 80 differs from that of the first to fourth embodiments.

[0066] The air ejection hole 82 in the sixth embodiment is a so-called shaped film hole. The air ejection hole 82 has a structure in which an inclined passage 82a and an expanded passage 82b are connected in sequence from the inlet to the outlet. As in the other embodiments, the inclined passage 82a is a portion that extends at an incline with the same inner diameter. The expanded passage 82b is connected to the air ejection hole 82 and has a circumferential width about the second axis O2 that increases radially inward and downstream until it opens to the first inner circumferential surface 54. This improves film efficiency and further suppresses flame stabilization at the film lip 55.

[0067] As a modified example of the sixth embodiment, for example, as shown in FIG. 9 , a structure may be adopted in which an inclined passage 82a, a widened passage 82b, and an extended passage 82c are connected in sequence from the inlet to the outlet. That is, in this modified example, an extended passage is connected to the outlet side of the widened passage 82b. The axial dimension of the extended passage 82c increases as it moves radially inward and downstream. The circumferential dimension of the extended passage 82c about the second axis O2 also increases as it moves radially inward and downstream. This also makes it possible to more reliably suppress flame stabilization at the film lip 55 while improving film efficiency, as described above.

[0068] <Other Embodiments> Although each embodiment of the present disclosure has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0069] <Additional Notes> The combustor 3 and the gas turbine 1 described in each embodiment can be understood as follows, for example.

[0070] (1) A combustor 3 according to a first aspect includes a nozzle 31 extending along the axis O2 and injecting fuel, and a burner cylinder 40 into which the nozzle 31 is inserted and into which the fuel is mixed with air A introduced from the upstream side to generate premixed gas, the burner cylinder 40 having a first inner circumferential surface 54 on the upstream side and a second inner circumferential surface 62 that is on the downstream side of the first inner circumferential surface 54 and has a larger diameter than the first inner circumferential surface 54 and extends further downstream, and further includes a first film supply section 70 formed between the first inner circumferential surface 54 and the second inner circumferential surface 62 and ejects first film air downstream along the second inner circumferential surface 62, and a second film supply section 80 formed on the first inner circumferential surface 54 and ejects second film air radially inward with respect to the axis O2 and toward the downstream side.

[0071] According to the above configuration, the first film supply unit 70 can supply first film air to the inner circumferential surface of the burner tube 40. This ensures flashback resistance. Furthermore, the second film air supplied to the inner circumferential surface of the burner tube body 50 by the second film supply unit 80 can suppress flame stabilization in the low flow velocity region, which is the step between the first inner circumferential surface 54 and the second inner circumferential surface 62.

[0072] (2) In the combustor 3 according to the second aspect, the burner cylinder 40 has a burner cylinder main body 50 that surrounds the nozzle 31 and has the first inner circumferential surface 54, and an extension pipe 60 that is fitted to the outer circumferential surface of the burner cylinder main body 50 and has the second inner circumferential surface 62 that extends downstream from the tip of the burner cylinder main body 50, and an annular space 90 that opens downstream at the tip of the burner cylinder main body 50 is defined and formed between the outer circumferential surface of the burner cylinder main body 50 and the second inner circumferential surface 62, and the extension pipe 60 has an air passage 100 on the outer circumferential side of the extension pipe 60 and a front air passage 110 The burner tube body 50 has an air A inlet that radially connects the annular space 90 to the space inside the burner tube body 50, and the burner tube body 50 extends downstream as it moves radially inward to connect the annular space 90 to the space inside the burner tube body 50, and has a hole group consisting of a plurality of air ejection holes 82 arranged in the circumferential direction, the first film supply section 70 being constituted by a first opening 71 at the downstream end of the annular space 90, and the second film supply section 80 being constituted by a second opening 81 that is the radially inner end of each of the air ejection holes 82 of the hole group.

[0073] This makes it possible to realize a configuration that includes both the first film supply unit 70 and the second film supply unit 80. This makes it possible to improve flashback resistance.

[0074] (3) A combustor 3 according to a third aspect is the combustor 3 according to (2), wherein the hole groups are arranged such that the radially outer ends of the air ejection holes 82 are positioned in the axial direction of the air introduction holes 63 in the annular space 90.

[0075] This makes it easier to introduce air A into each air ejection hole 82, and the flow rate of the second film air from the second film supply section 80 can be increased.

[0076] (4) A fourth aspect of the combustor 3 is the combustor 3 according to (2), wherein the hole groups are arranged such that the radially outer ends of the air ejection holes 82 are located downstream of the air introduction holes 63 in the annular space 90 in the axial direction.

[0077] This allows the second film air to be supplied from a position close to the low flow velocity region, which is the step between the first inner circumferential surface 54 and the second inner circumferential surface 62, thereby further suppressing flame stabilization in the low flow velocity region.

[0078] (5) A combustor 3 according to a fifth aspect is the combustor 3 of (2), wherein the hole groups include a first group in which radially outer ends of the air ejection holes 82 are located at the axial position of the air introduction holes 63 in the annular space 90, and a second group in which radially outer ends of the air ejection holes 82 are located at the axial position downstream of the air introduction holes 63 in the annular space 90.

[0079] This makes it possible to further prevent flame stabilization in the low flow velocity region where the step between the first inner circumferential surface 54 and the second inner circumferential surface 62 occurs, while increasing the flow rate of the second film air.

[0080] (6) A combustor 3 according to a sixth aspect is the combustor 3 according to any one of (2) to (5), in which the hole groups are arranged alternately on the upstream side and the downstream side in the circumferential direction of the axis O2.

[0081] This allows the air ejection holes 82 to be arranged closely together while ensuring the structural strength of the burner tube body 50 .

[0082] (7) The combustor 3 according to the seventh aspect is any of the combustors 3 of (2) to (6), in which the air ejection holes 82 are shaped film holes whose circumferential width about the axis O2 increases from the radially outer side toward the radially inner side and which are connected to the inner surface of the burner tube body 50.

[0083] This can improve the film efficiency of the second film air from the second film supply section 80.

[0084] (8) The combustor 3 according to an eighth aspect is the combustor 3 according to any one of (2) to (6), wherein the air ejection holes 82 are slit-shaped and extend in the circumferential direction of the axis O2.

[0085] This allows for a smaller amount of film air to be used, ensuring high film efficiency.

[0086] (9) A combustor 3 according to a ninth aspect includes any one of the combustors 3 of (1) to (8) that generates combustion gas by mixing the fuel with the air A and burning the mixture, a compressor 2 that supplies the compressed air A to the combustor 3, and a turbine 4 that is driven by the combustion gas generated by the combustor 3.

[0087] According to the present disclosure, flashback resistance can be improved.

[0088] REFERENCE SIGNS LIST 1 gas turbine 2 compressor 3 combustor 4 turbine 10 outer casing 11 end cover 12 pilot fuel port 13 main fuel port 15 inner casing 16 strut 17 combustion casing 18 leaf spring seal 19 base plate 20 pilot burner 21 pilot swirler 22 pilot nozzle 23 pilot burner casing 24 cylindrical portion 25 pilot cone 30 main burner 31 main nozzle 32 main swirler 40 main burner casing 50 burner casing body 50a large diameter portion 50b reduced diameter portion 50c small diameter portion 51 upstream outer peripheral surface 52 downstream outer peripheral surface 53 stepped surface 54 first inner peripheral surface 55 film lip 60 extension pipe 61 extended outer peripheral surface 62 second inner peripheral surface 63 air introduction hole 70 first film supply section 71 First opening 80 Second film supply section 81 Second opening 82 Air ejection hole 82a Inclined passage 82b Widened passage 82c Expanded passage 90 Annular space 100 Air passage 110 Premixing space 120 Combustion region A Air O1 First axis O2 Second axis

Claims

1. A combustor comprising: a nozzle that extends along an axis and injects fuel; and a burner cylinder into which the nozzle is inserted and in which a premixed gas is generated by mixing air introduced from an upstream side and the fuel, wherein the burner cylinder has: a first inner peripheral surface on the upstream side; and a second inner peripheral surface that has a larger diameter than the first inner peripheral surface on the downstream side of the first inner peripheral surface and extends further downstream, and further comprising: a first film supply portion that is formed between the first inner peripheral surface and the second inner peripheral surface and ejects first film air downstream along the second inner peripheral surface; and a second film supply portion that is formed on the first inner peripheral surface and ejects second film air radially inward and downstream of the axis.

2. The burner cylinder of claim 1, wherein the burner cylinder has: a burner cylinder body that surrounds the nozzle and has the first inner peripheral surface; and an extension pipe that is fitted to the outer peripheral surface of the burner cylinder body and has the second inner peripheral surface that extends downstream of the tip of the burner cylinder body, and an annular space that opens downstream at the tip of the burner cylinder body is defined between the outer peripheral surface of the burner cylinder body and the second inner peripheral surface, the extension pipe has an air introduction hole that radially communicates an air passage on the outer peripheral side of the extension pipe and the annular space, the burner cylinder body extends downstream toward the radially inner side to communicate the annular space and the space inside the burner cylinder body, and has a hole group composed of a plurality of air ejection holes arranged in the circumferential direction, the first film supply portion is constituted by a first opening at the downstream end of the annular space, and the second film supply portion is constituted by a second opening that is the radially inner end of each of the air ejection holes in the hole group.

3. The combustor according to claim 2, wherein in the hole group, the radially outer ends of the air ejection holes are arranged at the axial position of the air introduction hole in the annular space.

4. The combustor according to claim 2, wherein in the hole group, the radially outer ends of the air ejection holes are arranged at an axial position downstream of the air introduction hole in the annular space.

5. The combustion device according to claim 2, wherein the hole group includes a first group in which the radially outer end portion of the air ejection hole is located at the axial position of the air introduction hole in the annular space, and a second group in which the radially outer end portion of the air ejection hole is located at the axial position downstream of the air introduction hole in the annular space.

6. The combustion device according to any one of claims 2 to 5, wherein the hole group is alternately arranged upstream and downstream in the circumferential direction of the axis.

7. The combustion device according to any one of claims 2 to 5, wherein the air ejection hole is a shaped film hole having a width in the circumferential direction of the axis increasing from the radially outer side to the radially inner side and connected to the inner circumferential surface of the burner cylinder body.

8. The combustion device according to any one of claims 2 to 5, wherein the air ejection hole has a slit shape extending in the circumferential direction of the axis.

9. A gas turbine comprising: the combustion device according to any one of claims 1 to 5, which generates combustion gas by mixing and burning the fuel with the air; a compressor that supplies the compressed air to the combustion device; and a turbine that is driven by the combustion gas generated by the combustion device.

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