Combustor and gas turbine

Abstract

To provide a combustor capable of improving flash back resistance.SOLUTION: A combustor includes: a nozzle extending along an axis to inject fuel; and a burner cylinder to which the nozzle is inserted and in which premixed gas is generated by mixing air introduced from an upstream side and fuel. The burner cylinder includes: a first inner peripheral surface on the upstream side; and a second inner peripheral surface located downstream of the first inner peripheral surface and having a wider diameter compared to the first inner peripheral surface, and further includes: a first film supply part formed between the first inner peripheral surface and the second inner peripheral surface to eject first film air to the downstream side along the second inner peripheral surface; and a second film supply part formed on the first inner peripheral surface to eject second film air toward the radial inner side of the axis and the downstream side.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a combustor and a gas turbine.

Background Art

[0002] Near the outlet of a premixing burner that performs premixed combustion, since the premixed gas flows along the inner peripheral surface, the flow velocity may partially decrease due to the development of the boundary layer. And flashback may occur where the flame transfers to the fuel high-concentration region formed by this decrease in flow velocity.

[0003] As a technique for suppressing this flashback, for example, Patent Document 1 discloses a technique of supplying film air along the inner peripheral surface of a burner cylinder constituting a premixing burner. Specifically, the burner cylinder of the premixing burner is composed of a burner cylinder main body and an extension pipe that is fitted to the outer peripheral surface of the burner cylinder main body and extends to the downstream side of the burner cylinder main body. Then, the air on the outer peripheral side of the premixing burner is supplied as film air along the inner peripheral surface of the extension pipe from the step portion between the inner peripheral surface of the burner cylinder main body and the inner peripheral surface of the extension pipe. Thereby, the occurrence of flashback is suppressed by eliminating the fuel high-concentration region.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Even if the technique of Patent Document 1 above is adopted, for example, when an abnormality such as a surge of a compressor that supplies air occurs, temporary flashback may occur. Due to this flashback, the flame may be held at the tip (film lip) of the burner cylinder main body where the flow velocity is low.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a combustor and a gas turbine capable of improving flashback resistance.

Means for Solving the Problems

[0007] In order to solve the above problems, a combustor according to the present disclosure includes a nozzle that extends along an axis and injects fuel, and a burner cylinder into which the nozzle is inserted and in which premixed gas is generated by mixing air introduced from the upstream side and the fuel. 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. 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 along the second inner peripheral surface toward the downstream side, and a second film supply portion that is formed on the first inner peripheral surface and ejects second film air toward the inside and downstream in the radial direction of the axis are further provided.

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

Effects of the Invention

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

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

MODE FOR CARRYING OUT THE INVENTION

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

[0012] Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4. As shown in FIG. 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 axis of the gas turbine 1. The combustor 3 mixes fuel with the air A compressed by the compressor 2 and burns it to generate high-temperature and high-pressure combustion gas.

[0013] <Combustor> Hereinafter, the configuration of the combustor 3 will be described with reference to FIGS. 2 to 4. As shown in FIG. 2, the combustor 3 includes an outer cylinder 10, an end cover 11, an inner cylinder 15, a combustion cylinder 17, a substrate 19, a pilot burner 20, and a main burner 30.

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

[0015] <End cover> The end cover 11 closes the end on one side (the left side in FIG. 2) of the outer cylinder 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 into the pilot burner 20 and a main fuel port 13 for introducing fuel into the main burner 30. As the fuel, for example, natural gas or hydrogen is used. A mixed fuel of natural gas and hydrogen may be used as the fuel.

[0016] <Inner cylinder> The inner cylinder 15 is coaxially arranged 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 to the other side in the axial direction (the right side in FIG. 2) than the outer cylinder 10. One end of the inner cylinder 15 in the axial direction is axially spaced apart from the end cover 11. The outer diameter of the inner cylinder 15 is smaller than the inner diameter of the outer cylinder 10. Thereby, 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. Compressed air A compressed by the compressor 2 flows through the flow path from the other side in the axial direction toward the one side in the axial direction.

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

[0018] <Combustion cylinder> The combustion cylinder 17 is a cylindrical member. The upstream portion of the combustion cylinder 17 has a cylindrical shape centered on the first axis O1 and is provided so as to cover the downstream tip of the inner cylinder 15 from the outer peripheral side. The downstream end of the combustion cylinder 17 is connected to the turbine 4. The combustion gas generated in the combustor 3 flows through the flow path inside the combustion cylinder 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 direction while urging the inner peripheral surface of the combustion cylinder 17 and the outer peripheral surface of the inner cylinder 15 to be separated from each other.

[0020] <Substrate> The substrate 19 is disk-shaped and extends along a plane orthogonal to the first axis O1 around the first axis O1. The outer peripheral edge of the substrate 19 is fixed to the inner peripheral surface of the inner cylinder 15 over the entire circumference. The substrate 19 is provided at an axial position overlapping the outer cylinder 10 in the inner cylinder 15. A plurality of holes through which the pilot burner 20 and the main burner 30 penetrate in the axial direction are formed in the substrate 19.

[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 is rod-shaped and extends along the first axis O1, and the upstream end is fixed to the end cover 11. Fuel is introduced into the pilot burner 20 from the downstream end through the 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 from the downstream side to the upstream side.

[0024] The pilot burner cylinder 23 has a cylindrical portion 24 and a pilot cone 25. The cylindrical portion 24 is cylindrical with the first axis O1 as the center, and is provided so as to surround the plurality of pilot swirlers 21 and the pilot nozzle 22 from the outer peripheral side. The outer peripheral ends of the plurality of pilot swirlers 21 are connected to the inner peripheral surface of the pilot burner 20. The pilot cone 25 is connected to the downstream end of the cylindrical portion 24 and extends downstream of 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 as to increase in diameter 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> The main burner 30 is a burner provided in plurality so as to surround the main burner 30 inside the inner cylinder 15. The main burners 30 are provided at positions radially outside the first axis O1 inside the inner cylinder 15 and are spaced apart from each other in the circumferential direction. The main burners 30 are provided along a second axis O2 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 the upstream end thereof is fixed to the end cover 11. Fuel is introduced into the main burner 30 from the downstream end through the main fuel port 13. The fuel is ejected from the vicinity of 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 peripheral surface of the main burner 30. The main swirlers 32 are provided so as to twist around the second axis O2 from the downstream side toward the upstream side.

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

[0029] <Burner cylinder main body> As shown in FIG. 3, the burner tube body 50 has a cylindrical shape centered on the second axis O2. The burner tube 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 peripheral side. As shown in FIG. 3, the burner tube body 50 has a large-diameter portion 50a, a reduced-diameter portion 50b, and a small-diameter portion 50c from the downstream side toward the upstream side.

[0030] The large-diameter portion 50a is a large-diameter portion located on the most upstream side of the burner tube body 50, and the inner peripheral surface is connected to the outer peripheral side ends of the plurality of main swirlers 32. The inner diameter of the large-diameter portion 50a is made uniform in the axial direction. The reduced-diameter portion 50b is connected so as to be continuous with the downstream end of the large-diameter portion 50a, and the diameter is reduced toward the downstream side. The small-diameter portion 50c is connected so as to be continuous with the downstream end of the reduced-diameter portion 50b, and is a portion that extends downstream of the tip of the main nozzle 31.

[0031] As shown in FIGS. 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 that is one step smaller in diameter than the upstream outer peripheral surface 51. The downstream outer peripheral surface 52 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 the downstream side.

[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 forms an annular shape centered on the second axis O2 and faces the downstream side.

[0033] <Extension pipe> The extension pipe 60 has a cylindrical shape with its upstream portion 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 circumferential direction of the first axis O1 as the longitudinal direction as it extends downstream. The outer peripheral surface of the extension pipe 60 is the extended outer peripheral surface 61. The inner peripheral surface of the extension pipe 60 is the 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 body 50. Thereby, the burner cylinder body 50 and the extension pipe 60 are 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 body 50.

[0035] An annular space 90 extending in the axial direction centered on the second axis O2 is defined between the downstream outer peripheral surface 52 of the small-diameter portion 50c of the burner cylinder body 50 and the second inner peripheral surface 62 of the extension pipe 60. The downstream end of the annular space 90 is the first opening 71 that opens to the radially outer portion of the film lip 55. The inner peripheral edge portion of 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 the portion of the extension pipe 60 upstream of the film lip 55 of the burner cylinder body 50, air introduction holes 63 are formed that penetrate in the radial direction to communicate the air passage 100 outside the extension pipe 60 with the annular space 90. A plurality of air introduction holes 63 are provided at intervals in the circumferential direction of the second axis O2. The upstream end of the air introduction holes 63 is at the same axial position as the stepped surface 53 of the small-diameter portion 50c of the burner cylinder body 50. The downstream end of the air introduction holes 63 is located upstream of the film lip 55. Thereby, in the upstream portion of the annular space 90, it faces the air passage 100 through the air introduction holes 63.

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

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

[0039] <Second film supply section> The second film supply section 80 ejects second film air downstream along the first inner peripheral surface 54. The second film supply section 80 is constituted by a second opening 81 of a plurality of air ejection holes 82.

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

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

[0042] <Function and effect> In the combustor 3 configured as described above, when the high-temperature and 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 the fuel injected from the main nozzle 31 to become a premixed gas. Then, the premixed gas passes through the extension pipe 60 and flows into the combustion cylinder 17.

[0043] The air A guided to the pilot burner 20 becomes a swirling airflow by the pilot swirler 21 inside the pilot burner cylinder 23, is mixed with the fuel injected from the pilot nozzle 22, and is ignited and burned by a kindling (not shown). The combustion gas generated thereby passes through the pilot cone 25 and is ejected into the combustion cylinder 17. At this time, a part of the combustion gas is ejected so as to diffuse around with a flame inside the combustion cylinder 17, whereby the premixed gas flowing into the combustion cylinder 17 from each main burner 30 is ignited and burned.

[0044] In this way, a flame retention for stabilizing the combustion of the premixed gas from the main burner 30 can be performed by the diffusion flame of the fuel ejected from the pilot burner 20. And the region where the premixed gas burns due to the diffusion flame from the pilot burner 20 becomes the combustion region 120.

[0045] By the way, in the combustor 3, when the boundary layer of the flow of the premixed gas develops on the inner peripheral surface of the main burner cylinder 40, a fuel high-concentration region is formed due to a partial decrease in the flow velocity. Then, when the flame in the combustion region 120 burns into such a fuel high-concentration region, flashback may occur.

[0046] On the other hand, in the present embodiment, the first film supply unit 70 can supply the first film air along the inner peripheral surface of the main burner cylinder 40. That is, as shown in FIG. 4, the air A in the air passage 100 on the outer peripheral side of the main burner cylinder 40 enters the annular space 90 from the air A inlet. Then, the air A flows into the annular space 90 toward the downstream side and jets out from the first opening 71 along the second inner peripheral surface 62 to the first film supply unit 70. Thereby, the fuel high-concentration region near the second inner peripheral surface 62 can be eliminated, and the occurrence of flashback can be suppressed.

[0047] Here, for example, when an abnormality such as a rotating stall of the compressor 2 of the gas turbine 1 occurs, temporary flashback may occur. Due to this flashback, the flame may be retained at the film lip 55 which is the step portion between the first inner peripheral surface 54 and the second inner peripheral surface 62. That is, the periphery of the film lip 55 formed to constitute the first film supply unit 70 is a region where the flow velocity is low in the premixed space 110. Also, the first film air cannot be supplied to this region.

[0048] In contrast, in the present embodiment, the second film air supplied from the second film supply unit 80 to the inner peripheral surface of the burner cylinder main body 50 can suppress the flame retention at the film lip 55. That is, as shown in FIG. 4, the air A introduced into the air introduction hole 63 not only flows through the annular space 90 but also enters each air ejection hole 82 facing the air introduction hole 63. Then, it obliquely flows through the air ejection hole 82 in the radially inner and downstream directions and is ejected from the second opening 81 formed on the first inner peripheral surface 54. The air A ejected in this way flows as the second film air flowing along the first inner peripheral surface 54. When the second film air reaches the film lip 55, it is possible to avoid the occurrence of a fuel high-concentration region in the film lip 55. As a result, flashback in the entire combustor 3 can be more effectively suppressed.

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

[0050] Particularly in the present embodiment, the inlet of the air ejection hole 82 serving as the supply source of the second film air is formed at the same axial position as the air introduction hole 63, that is, the inlet of the air ejection hole 82 faces the air passage 100 through the air introduction hole 63. Therefore, the introduction of the air A into the air ejection hole 82 can be promoted. Thus, the flow rate of the second film air can be appropriately ensured.

[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 reference numerals are given to the same components as in the first embodiment, and detailed descriptions thereof are omitted. The combustor 3 of the second embodiment is different from that of the first embodiment in the configuration of the second film supply unit 80.

[0052] That is, in the second embodiment, the plurality of air ejection holes 82 are alternately arranged on the upstream side and the downstream side in the circumferential direction, and the radially outer ends of the respective air ejection holes 82 are in the axial direction position of the air introduction hole 63, similar to the first embodiment.

[0053] Thereby, while maintaining the structural strength of the burner cylinder main body 50, the second openings 81 can be arranged with high density, so that the flow rate of the second film air can be more appropriately ensured.

[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 other embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted. The combustor 3 of the third embodiment is different from other embodiments in the configuration of the second film supply unit 80.

[0055] That is, in the third embodiment, while the air ejection holes 82 have the same arrangement structure as in the second embodiment, the arrangement positions are different. The air ejection holes 82 of the third embodiment are provided on the tip side of the burner cylinder main body 50 rather than in the second embodiment. The radially outer ends of the respective air ejection holes 82 are located on the downstream side of the air introduction hole 63. Therefore, the openings at the inlets of the respective air ejection holes 82 do not face the air passage 100 through the air introduction hole 63.

[0056] Thereby, the air A introduced into the annular space 90 through the air introduction hole 63 flows through the narrow space between the burner cylinder main body 50 and the extension pipe 60, and a part of it is ejected from the first opening 71 to become the first film air, and the other is introduced into the air ejection hole 82 and ejected from the second opening 81 to become the second film air.

[0057] Thereby, the second film air can be supplied from closer to the film lip 55 where flame retention is likely to occur during abnormal times. Therefore, flame retention at the film lip 55 can be more suppressed, and even if flame retention occurs at the film lip 55, the flame retention 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 other embodiments are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In the combustor 3 of the fourth embodiment, the configuration of the second film supply unit 80 is different from that of other embodiments.

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

[0060] Accordingly, as in the second embodiment, while appropriately securing the flow rate of the second film air, the second film air can be supplied from a location closer to the film lip 55 where flashback is likely to occur. Therefore, it is possible to further suppress and eliminate flashback at the film lip 55.

[0061] In the third and fourth embodiments, the arrangement of each hole group is the same as that of the second embodiment. However, the axial positions of the air ejection holes 82 constituting each hole group may be the same as those 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 other embodiments are denoted by the same reference numerals, and detailed descriptions thereof are omitted. In the combustor 3 of the fifth embodiment, the air ejection holes 82 constituting the second film supply unit 80 are slit-shaped.

[0063] That is, the air ejection holes 82 of the fifth embodiment are in a slit shape extending in the circumferential direction as the longitudinal direction. A plurality of such slit-shaped air ejection holes 82 are formed at intervals in the circumferential direction. Thereby, an equivalent film effect can be ensured with a smaller film air amount compared to other embodiments. Therefore, flashback can be effectively suppressed while maintaining the performance of the combustor 3.

[0064] Note that the slit-shaped air ejection holes 82 may be configured to be arranged 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 fifth and sixth embodiments, the same reference numerals are given to the same components as in the other embodiments, and detailed descriptions thereof are omitted. In the sixth embodiment, the configuration of each air ejection hole 82 constituting the second film supply unit 80 is different from that of the first to fourth embodiments.

[0066] The air ejection hole 82 of 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 a widened passage 82b are sequentially connected from the inlet to the outlet. The inclined passage 82a is a portion that extends inclined with the same inner diameter as in other embodiments. The widened passage 82b is connected to the air ejection hole 82 and is a portion that opens to the first inner peripheral surface 54 such that the circumferential width of the second axis O2 increases toward the radially inner side and the downstream side. Thereby, the film efficiency can be improved, and it becomes possible to further suppress the flame holding at the film lip 55.

[0067] As a modification of the sixth embodiment, for example, as shown in FIG. 9, a structure in which an inclined passage 82a, a widened passage 82b, and an extended passage 82c are sequentially connected from the inlet toward the outlet side may be employed. That is, in this modification, an extended passage is connected to the outlet side of the widened passage 82b. The extended passage 82c has an axial dimension that increases toward the radially inner side and the downstream side. The extended passage 82c of the present embodiment also has a circumferential dimension of the second axis O2 that increases toward the radially inner side and the downstream side. Also by this, as in the above, while improving the film efficiency, it is possible to more reliably suppress the flame retention at the film lip 55.

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

[0069] <Supplementary Note> The combustor 3 and the gas turbine 1 described in each embodiment are understood as follows, for example.

[0070] (1) The combustor 3 according to the first aspect extends along the axis O2 and includes a nozzle 31 that injects fuel, and a burner cylinder 40 into which the nozzle 31 is inserted and in which a premixed gas is generated by mixing air A introduced from the upstream side and the fuel. The burner cylinder 40 has an upstream first inner peripheral surface 54 and a second inner peripheral surface 62 that has a larger diameter than the first inner peripheral surface 54 on the downstream side of the first inner peripheral surface 54 and extends further downstream. A first film supply portion 70 that is formed between the first inner peripheral surface 54 and the second inner peripheral surface 62 and ejects first film air along the second inner peripheral surface 62 toward the downstream side, and a second film supply portion 80 that is formed on the first inner peripheral surface 54 and ejects second film air toward the radially inner side and the downstream side of the axis O2 are further provided.

[0071] According to the above configuration, the first film supply portion 70 can supply the first film air to the inner peripheral surface of the burner cylinder 40. Thereby, the flashback resistance can be ensured. Further, the second film air supplied from the second film supply unit 80 to the inner peripheral surface of the burner cylinder main body 50 can suppress flame retention in the low flow velocity region, which is the stepped portion between the first inner peripheral surface 54 and the second inner peripheral surface 62.

[0072] (2) The combustor 3 according to the second aspect, wherein the burner cylinder 40 includes a burner cylinder main body 50 that surrounds the nozzle 31 and has the first inner peripheral surface 54, and is fitted to the outer peripheral surface of the burner cylinder main body 50 and extends downstream from the tip of the burner cylinder main body 50. And an extension pipe 60 having the second inner peripheral surface 62, and an annular space 90 that opens downstream at the tip of the burner cylinder main body 50 is defined between the outer peripheral surface of the burner cylinder main body 50 and the second inner peripheral surface 62. The extension pipe 60 has an air A inlet that radially communicates the air passage 100 on the outer peripheral side of the extension pipe 60 with the annular space 90. The burner cylinder main body 50 extends downstream toward the radially inner side to communicate the annular space 90 with the space inside the burner cylinder main body 50, and has a hole group including a plurality of air ejection holes 82 arranged in the circumferential direction. The first film supply unit 70 is constituted by a first opening 71 at the downstream end of the annular space 90, and the second film supply unit 80 is 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] Thereby, a configuration including both the first film supply unit 70 and the second film supply unit 80 can be realized. Therefore, it is possible to improve the flashback resistance.

[0074] (3) The combustor 3 according to the third aspect, wherein the hole group is arranged such that the radially outer end of each of the air ejection holes 82 is at the axial position of the air introduction hole 63 in the annular space 90, which is the combustor 3 of (2).

[0075] Thereby, it is possible to easily introduce the air A into each of the air ejection holes 82, and it is possible to increase the flow rate of the second film air by the second film supply unit 80.

[0076] (4) The combustor 3 according to the fourth aspect is the combustor 3 of (2) in which the hole group is arranged such that the radially outer end of each air ejection hole 82 is at the axial position downstream of the air introduction hole 63 in the annular space 90.

[0077] Thereby, the secondary film air can be supplied from a position close to the low flow velocity region that becomes the stepped portion between the first inner peripheral surface 54 and the second inner peripheral surface 62. Therefore, the flame holding in the low flow velocity region can be further suppressed.

[0078] (5) The combustor 3 according to the fifth aspect is the combustor 3 of (2) including a first group in which the radially outer end of the air ejection hole 82 is at the axial position of the air introduction hole 63 in the annular space 90, and a second group in which the radially outer end of the air ejection hole 82 is at the axial position downstream of the air introduction hole 63 in the annular space 90.

[0079] Thereby, while increasing the flow rate of the secondary film air, the flame holding in the low flow velocity region that becomes the stepped portion between the first inner peripheral surface 54 and the second inner peripheral surface 62 can be further prevented.

[0080] (6) The combustor 3 according to the sixth aspect is the combustor 3 of any one of (2) to (5) in which the hole group is alternately arranged upstream and downstream in the circumferential direction of the axis O2.

[0081] Thereby, the air ejection holes 82 can be arranged densely while ensuring the structural strength of the burner cylinder main body 50.

[0082] (7) The combustor 3 according to the seventh aspect is the combustor 3 of any one of (2) to (6) in which the air ejection hole 82 is a shaped film hole that becomes wider in the circumferential direction of the axis O2 from the radially outer side toward the radially inner side and is connected to the inner peripheral surface of the burner cylinder main body 50.

[0083] As a result, the film efficiency of the second film air by the second film supply unit 80 can be improved.

[0084] (8) The combustor 3 according to the eighth aspect is the combustor 3 according to any one of (2) to (6) in which the air ejection hole 82 has a slit shape extending in the circumferential direction of the axis O2.

[0085] As a result, the film efficiency can be ensured high with a smaller amount of film air.

[0086] (9) The combustor 3 according to the ninth aspect includes the combustor 3 according to any one of (1) to (8) that generates combustion gas by mixing and burning the fuel with the air A, 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.

Explanation of reference numerals

[0087] 1 Gas turbine 2 Compressor 3 Combustor 4 Turbine 10 Outer cylinder 11 End cover 12 Pilot fuel port 13 Main fuel port 15 Inner cylinder 16 Strut 17 Combustion cylinder 18 Leaf spring seal 19 Substrate 20 Pilot burner 21 Pilot swirler 22 Pilot nozzle 23 Pilot burner cylinder 24 Cylindrical part 25 Pilot cone 30 Main burner 31 Main nozzle 32 Main swirler 40 Main burner cylinder 50 Burner cylinder body 50a Large-diameter portion 50b Reduced-diameter portion 50c Small-diameter portion 51 Upstream outer peripheral surface 52 Downstream outer peripheral surface 53 Step surface 54 First inner peripheral surface 55 Film lip 60 Extension pipe 61 Extension outer peripheral surface 62 Second inner peripheral surface 63 Air inlet 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 Widening passage 82c Expansion passage 90 Annular space 100 Air passage 110 Premixing space 120 Combustion region A Air O1 First axis O2 Second axis

Claims

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

2. The burner cylinder includes a burner cylinder body that surrounds the nozzle and has the first inner peripheral surface, 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 has an annular space that is partitioned and formed between the outer peripheral surface of the burner cylinder body and the second inner peripheral surface and opens downstream at the tip of the burner cylinder body, the extension pipe has an air introduction hole that radially communicates the 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 and communicates 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, The combustor according to claim 1, wherein the second film supply portion is constituted by a second opening that is the radially inner end portion of each of the air ejection holes of the hole group.

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

5. The hole group includes a first group in which the radially outer end portions of the air ejection holes are at the axial position of the air introduction hole in the annular space, a second group in which the radially outer end portions of the air ejection holes are at the axial position downstream of the air introduction hole in the annular space, The combustor according to claim 2, comprising

6. The combustor according to any one of claims 2 to 5, wherein the hole groups are alternately arranged on the upstream side and the downstream side as going in the circumferential direction of the axis.

7. The combustor according to any one of claims 2 to 5, wherein the air ejection holes are shaped film holes that are connected to the inner peripheral surface of the burner cylinder main body, with the width in the circumferential direction of the axis increasing from the radially outer side toward the radially inner side.

8. The combustor according to any one of claims 2 to 5, wherein the air ejection holes are in a slit shape extending in the circumferential direction of the axis.

9. A combustor 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 combustor; A turbine driven by the combustion gas generated by the combustor; A gas turbine comprising

Images