Burner and combustor

Abstract

A burner (3) according to one embodiment is for generating a flame by burning an air / gas fuel mixture gas, and the burner comprises a cylindrical body (4A) that surrounds a premixing zone (40) including a plurality of mixing flow paths (8) disposed in the circumferential direction. The cylindrical body (4A) forms a nozzle (41) that injects the mixture gas. Further, the burner (3) comprises a plurality of static mixers (9) that mix the gas fuel and the air and that are disposed in the respective mixture flow paths (8).

Description

Burners and Combustors

[0001] The present disclosure relates to a burner for generating a flame, and a combustor including said burner.

[0002] Burners for burning a mixture of gas fuel and air to generate a flame have been known. For example, Patent Document 1 discloses a burner used in a combustor of a gas turbine. In Patent Document 1, the burner is referred to as a "fuel nozzle."

[0003] Specifically, the burner in Patent Document 1 includes a cylindrical body, a shaft body located at the center of the cylindrical body, and a plurality of swirl vanes protruding radially from the shaft body. Each swirl vane has a plurality of fuel injection holes formed therein, and the swirl vanes form a swirling flow of a fuel-air mixture.

[0004] Furthermore, in the burner of Patent Document 1, a flow path forming cylinder centered on the shaft is used to prevent flashback caused by fuel stagnation in the vortex core of the swirling flow at the injection port formed by the cylindrical body.

[0005] The flow passage forming cylinder is penetrated by the plurality of swirl vanes, and forms a flow passage for the swirling flow between the cylinder and the shaft, and forms a flow passage for air between the cylinder and the shaft. Air is supplied to the vortex core of the swirling flow through the flow passage between the flow passage forming cylinder and the shaft, thereby preventing flashback.

[0006] JP 2018-189288 A

[0007] However, with the burner of Patent Document 1, it is difficult to achieve a uniform fuel concentration distribution in the air-fuel mixture at the injection port, and there is a risk that the degree of premixing at the injection port will be insufficient.

[0008] Therefore, an object of the present disclosure is to provide a burner that can achieve a sufficient degree of premixing at the injection port while preventing flashback into the cylinder, and a combustor including the burner.

[0009] From one aspect, the present disclosure provides a burner for burning a mixture of gas fuel and air to generate a flame, the burner comprising: a cylinder that forms an injection port for the mixture and surrounds a premixing zone including a plurality of mixing passages arranged circumferentially; and a plurality of static mixers that mix the gas fuel and the air, each arranged in one of the plurality of mixing passages.

[0010] In another aspect, the present disclosure provides a combustor including a plurality of the burners described above.

[0011] According to the present disclosure, there are provided a burner that can achieve a sufficient degree of premixing at the injection port while preventing flashback into the cylinder, and a combustor including the burner.

[0012] 1 is a cross-sectional view of a combustor including a burner according to one embodiment; 2 is a perspective view of the burner, with a portion of the burner shown in cross section; 3 is a cross-sectional view of an upstream portion of the burner, with a first cylindrical body of the burner shown in cross section; 4 is a cross-sectional view taken along line IV-IV in FIG. 3; 5A and 5B are a front view and a perspective view, respectively, of a basic shape of a static mixer;

[0013] Fig. 2 shows a burner 3 according to one embodiment, and Fig. 1 shows a combustor 1 including a plurality of burners 3. For example, the combustor 1 is used in a gas turbine or the like.

[0014] The combustor 1 includes an outer cylinder 11, an inner cylinder 12 housed in the outer cylinder 11, and an end plate 13 that closes one opening of the outer cylinder 11 and the inner cylinder 12. For ease of explanation, the side of the end plate 13 in the axial direction of the outer cylinder 11 and the inner cylinder 12 will be referred to as the front, and the opposite side will be referred to as the rear.

[0015] A cylindrical flow path that opens toward the rear is formed between the inner cylinder 12 and the outer cylinder 11. Air is supplied to this cylindrical flow path from the rear. For example, the air supplied to the cylindrical flow path is compressed air.

[0016] A partition wall 14 is provided within the inner cylinder 12, dividing the space within the inner cylinder 12 into a front air chamber 15 and a rear combustion chamber 16. Furthermore, a straightening plate 18 is provided within the air chamber 15, dividing the air chamber 15 into a pre-straightening space 15a and a post-straightening space 15b. A portion of the inner cylinder 12 facing the pre-straightening space 15a has multiple openings, through which air flows from the cylindrical flow path into the pre-straightening space 15a. The straightening plate 18 has multiple through-holes, which straighten the air that flows into the pre-straightening space 15a into a uniform flow along the axial direction of the inner cylinder 12. Therefore, a uniform flow of air flows into the post-straightening space 15b along the axial direction of the inner cylinder 12.

[0017] A plurality of burners 3 are arranged in the post-straightening space 15b. The burners 3 are intended to generate a flame in the combustion chamber 16. For example, the burners 3 are arranged at equal angular intervals on at least one circumference centered on the center line of the inner cylinder 12. Each burner 3 extends in the front-rear direction, and the rear end of each burner 3 penetrates the partition wall 14. In the illustrated example, the rear end face of each burner 3 is located rearward of the rear face of the partition wall 14, but the rear end face of each burner 3 may be flush with the rear face of the partition wall 14. Alternatively, each burner 3 does not necessarily have to penetrate the partition wall 14, and the rear end face of each burner 3 may be joined to the front face of the partition wall 14.

[0018] In this embodiment, the front end of each burner 3 is connected to the end plate 13 by a fuel supply pipe 22 that extends in the front-rear direction and penetrates the straightening plate 18. Gas fuel is supplied to all the burners 3 through a gas fuel supply passage 21 and the fuel supply pipe 22. The gas fuel is, for example, natural gas or hydrogen.

[0019] A portion of the air that has flowed into the post-straightening space 15b flows as combustion air into each burner 3. In this embodiment, a portion of the air that has flowed into the post-straightening space 15b also flows into each burner 3 as protective air.

[0020] Each burner 3 forms a mixture of combustion air and gas fuel inside, and injects the mixture into the combustion chamber 16. The combustor 1 includes an ignition device 17 that ignites the mixture injected from each burner 3 in the combustion chamber 16. The ignition device 17 penetrates the inner cylinder 12 and the outer cylinder 11. A flame is generated in the combustion chamber 16 when the mixture is ignited by the ignition device 17. In this embodiment, a flame is also generated in each burner 3 as the flame propagates into the burner 3. Note that a plurality of ignition devices 17 may be provided so as to be scattered in the circumferential direction.

[0021] Next, the structure of each burner 3 will be described in detail with reference to Figure 2. The burner 3 includes a first cylindrical body 4A and a second cylindrical body 4B arranged coaxially. The axial direction of the first cylindrical body 4A and the second cylindrical body 4B is the front-to-rear direction. The second cylindrical body 4B is arranged outside the first cylindrical body 4A, and the first cylindrical body 4A and the second cylindrical body 4B partially overlap each other.

[0022] The first cylindrical body 4A surrounds a premixing zone 40 including a plurality of mixing passages 8 arranged in the circumferential direction. The first cylindrical body 4A forms an injection port 41 for an air-fuel mixture of combustion air and gas fuel. In this embodiment, the first cylindrical body 4A is parallel to the axial direction from approximately the center to the front, but the diameter decreases from approximately the center to the rear toward the injection port 41. However, the first cylindrical body 4A may be parallel to the axial direction over its entire length.

[0023] A shaft 51 is located at the center of the first cylindrical body 4A. The shaft 51 tapers toward the rear.

[0024] A plurality of partition walls 52 protrude radially from the shaft body 51. The partition walls 52 divide the space between the shaft body 51 and the first cylindrical body 4A into a plurality of mixing flow paths 8. Each partition wall 52 has a rectangular shape that is long in the front-to-rear direction, perpendicular to the circumferential direction of the first cylindrical body 4A. The cross-sectional shape of each mixing flow path 8 is fan-shaped.

[0025] A plurality of static mixers 9 for mixing the mixture of gas fuel and combustion air are arranged in the mixing passage 8. The static mixers 9 will be described in detail later.

[0026] Furthermore, a fuel introduction body 6 extends from the shaft body 51 toward the opposite side of the injection port 41. The fuel introduction body 6 is columnar and its center coincides with that of the shaft body 51. The fuel introduction body 6 constitutes the front end portion of the burner 3 described above.

[0027] 3, in this embodiment, the front end of the shaft 51 is located rearward of the front end of the first cylindrical body 4A, and the rear end of the fuel introduction body 6 is inserted into the first cylindrical body 4A. However, the front end of the shaft 51 may coincide with the front end of the first cylindrical body 4A, and the entire fuel introduction body 6 may be located outside the first cylindrical body 4A.

[0028] 4, the fuel introducing body 6 is hollow and forms a fuel introducing chamber 61. More specifically, the fuel introducing body 6 includes a peripheral wall 6a extending in the front-rear direction, a front wall 6b that closes a front opening of the peripheral wall 6a, and a rear wall 6c that closes a rear opening of the peripheral wall 6a.

[0029] An inlet 62 is provided at the center of the front wall 6b. The above-mentioned fuel supply pipe 22 is connected to the inlet 62, and gas fuel is introduced from the fuel supply pipe 22 through the inlet 62 into the fuel introduction chamber 61. The corner between the front surface of the front wall 6b and the outer circumferential surface of the peripheral wall 6a is rounded to prevent separation of the combustion air flowing in the front-to-rear direction.

[0030] A plurality of fuel distribution tubes 7 protrude radially from the rear end of the fuel introducing body 6. In this embodiment, the fuel distribution tubes 7 are located inside the first cylindrical body 4A, but the fuel distribution tubes 7 may also be located outside the first cylindrical body 4A.

[0031] The fuel distribution tube 7 passes through the center of adjacent partition walls 52 when viewed in the axial direction of the first cylindrical body 4A. The interior of each fuel distribution tube 7 is in communication with the fuel introduction chamber 61. Each fuel distribution tube 7 includes a plurality of fuel injection holes 71. In this embodiment, each fuel distribution tube 7 has four fuel injection holes 71, but the number of fuel injection holes 71 can be changed as appropriate. The gas fuel introduced into the fuel introduction chamber 61 is injected from the fuel injection holes 71 through the interior of the fuel distribution tube 7.

[0032] In this embodiment, since each partition wall 52 extends to the outside of the rear end of the fuel introducing body 6, each fuel distribution tube 7 is located between the front ends of adjacent partition walls 52. Therefore, an opening for passing combustion air is formed between each fuel distribution tube 7 and the partition walls 52 located on both sides of it. A portion of the air that has flowed into the post straightening space 15b flows rearward around the fuel introducing body 6 and flows into the mixing flow passage 8 as combustion air through the opening between the fuel distribution tube 7 and the partition wall 52. However, each fuel distribution tube 7 may be located forward of the partition wall 52, and an opening for passing combustion air may be formed between adjacent fuel distribution tubes 7.

[0033] 3, the cross-sectional shape of each fuel distribution tube 7 is such that the length in the axial direction of the first cylindrical body 4A is longer than the width in the circumferential direction of the first cylindrical body 4A. In this embodiment, the cross-sectional shape of each fuel distribution tube 7 is substantially elliptical. This makes it possible to ensure a large opening area for the passage of combustion air in the circumferential direction of the first cylindrical body 4A at the position where the fuel distribution tube 7 is located, while also ensuring a large wall thickness of the fuel distribution tube 7 in the axial direction of the first cylindrical body 4A.

[0034] As shown in Figure 2, the second cylindrical body 4B extends from the middle of the portion where the diameter of the first cylindrical body 4A narrows to a position away from the first cylindrical body 4A. The diameter of the second cylindrical body 4B narrows downstream in the region where it overlaps with the first cylindrical body 4A, but expands downstream in the region further aft. The second cylindrical body 4B surrounds the combustion zone 42 downstream of the first cylindrical body 4A.

[0035] A cylindrical flow path 32 is formed between the first cylindrical body 4A and the second cylindrical body 4B. The front end of the second cylindrical body 4B is supported by a plurality of supports 31 scattered circumferentially on the outer peripheral surface of the first cylindrical body 4A. The cylindrical flow path 32 opens into the post-straightening space 15b through the gaps between the supports 31. Therefore, a portion of the air that flows into the post-straightening space 15b flows into the cylindrical flow path 32 as protective air. The protective air is supplied from the cylindrical flow path 32 to the combustion zone 42 so as to flow along the inner peripheral surface of the second cylindrical body 4B.

[0036] Next, the structure of each static mixer 9 will be described in detail. Each static mixer 9 includes a plurality of blades 91 whose twist direction alternates. In this embodiment, there are three blades 91, but the number of blades 91 can be changed as needed. The twist center 90 of each blade 91 shown in Figure 4 is located on the central plane that bisects the corresponding mixing channel 8 in the circumferential direction of the first cylindrical body 4A.

[0037] In this embodiment, the twisting manner of the blades 91 is the same in all static mixers 9. More specifically, in each static mixer 9, the blades 91 in odd-numbered stages from the upstream side are twisted counterclockwise when viewed from the upstream side, and the blades 91 in even-numbered stages from the upstream side are twisted clockwise when viewed from the upstream side.

[0038] If the twisting manner of the blades 91 of adjacent static mixers 9 is opposite, there is a risk of a large deviation in the fuel concentration after the mixture is combined immediately downstream of the static mixers 9. In contrast, if the twisting manner of the blades 91 of all static mixers 9 is the same, it is possible to reduce the deviation in the fuel concentration after the mixture is combined immediately downstream of the static mixers 9.

[0039] 5A and 5B show the basic shape 95 of the static mixer 9. The basic shape 95 is formed by rotating a rod 180 degrees around its center while moving it in a direction perpendicular to the rod, and repeating this process while reversing the direction of rotation and shifting the direction of the rod at the start of rotation by 90 degrees. The static mixer 9 has a shape obtained by cutting the basic shape 95 to fit the shape of the mixing channel 8.

[0040] That is, the twist angle of each blade 91 in each static mixer 9 is 180 degrees. The first upstream blade 91A of the blades 91 has a leading edge 92 and a trailing edge 93 extending in the radial direction of the first cylindrical body 4A.

[0041] In this embodiment, the second-stage blade 91B from the upstream side is pointed toward the torsion center 90 of the first-stage blade 91A, and the third-stage blade 91C from the upstream side is pointed toward the torsion center 90 of the second-stage blade 91B. In other words, the blades 91 other than the first stage blade are pointed toward the torsion center 90 of the upstream blade 91.

[0042] For this reason, the leading edges 92 of the second-stage blades 91B and the third-stage blades 91C are not straight but rather have a mountain-like shape. The angles that the leading edges 92 of the second-stage blades 91B and the third-stage blades 91C make with the plane perpendicular to the torsion center 90 on both sides of the torsion center 90 are, for example, 30 degrees.

[0043] On the other hand, the second-stage blade 91B has a trailing edge 93 that is perpendicular to the radial direction of the first cylindrical body 4A, and the third-stage blade 91C has a trailing edge 93 that extends in the radial direction of the first cylindrical body 4A. As described above, in this embodiment, when viewed from the extension direction of the torsion center 90 of the blade 91, the trailing edge 93 of the upstream blade 91 and the leading edge 92 of the downstream blade 91 intersect in a cross shape. Therefore, each of the flows bisected by the upstream blade 91 is further bisected by the leading edge 92 of the downstream blade 91, thereby enabling efficient mixing of the gas fuel and air.

[0044] In this embodiment, a baffle plate 72 that is perpendicular to the circumferential direction of the first cylindrical body 4A is interposed between the leading edge 92 of the first-stage vane 91A and the corresponding fuel distribution tube 7. The baffle plate 72 has the same length as the corresponding fuel distribution tube 7, and is provided integrally with the corresponding fuel distribution tube 7 and vane 91A. However, the baffle plate 72 can be omitted.

[0045] 3 and 4 , the fuel injection holes 71 of each fuel distribution tube 7 described above include a plurality of first fuel injection holes 71A that inject fuel toward the twisting direction of the outer ends 92 a of the leading edges 92 of the first-stage blades 91A of the corresponding static mixer 9, and a plurality of second fuel injection holes 71B that inject fuel toward the twisting direction of the inner ends 92 b of the leading edges 92 of the first-stage blades 91A. In this embodiment, the number of first fuel injection holes 71A and the number of second fuel injection holes 71B are two, but the numbers of first fuel injection holes 71A and second fuel injection holes 71B can be changed as appropriate.

[0046] Furthermore, in this embodiment, all of the second fuel injection holes 71B are located in a region more inward than the center of the corresponding fuel distribution tube 7. Meanwhile, one of the first fuel injection holes 71A is located in a region more inward than the center of the corresponding fuel distribution tube 7, and the other of the first fuel injection holes 71A is located in a region more outward than the center of the corresponding fuel distribution tube 7. Whether the number of first fuel injection holes 71A is two or three or more, it is desirable that at least one of the first fuel injection holes 71A is located in a region more outward than the center of the corresponding fuel distribution tube 7.

[0047] Furthermore, in this embodiment, the diameters of the two second fuel injection holes 71B and the first fuel injection hole 71A located radially inside the first cylindrical body 4A are equal, and the diameter of the first fuel injection hole 71A located radially outside the first cylindrical body 4A is larger than the diameters of the two second fuel injection holes 71B and the first fuel injection hole 71A located radially inside the first cylindrical body 4A. In other words, in each fuel distribution tube 7, the diameter of the fuel injection hole 71 farthest from the fuel introducer 6 is larger than the diameter of the fuel injection hole 71 closest to the fuel introducer 6.

[0048] When the cross section of the mixing flow path 8 is sector-shaped as in this embodiment, the distance from the fuel distribution tube 7 to the partition wall 52 is short on the radially inner side of the first cylindrical body 4A, and the distance from the fuel distribution tube 7 to the partition wall 52 is long on the radially outer side of the first cylindrical body 4A. Therefore, if the diameter of the fuel injection hole 71 farthest from the fuel introduction body 6 is large, the gas fuel can be injected up to close to the partition wall 52 on the radially outer side of the first cylindrical body 4A.

[0049] As described above, in the burner 3 of this embodiment, the gas fuel and air are mixed by the static mixers 9 arranged in the circumferentially aligned mixing passages 8, which makes it possible to uniform the fuel concentration distribution in the mixture at the injection port 41, that is, to achieve a sufficient degree of premixing at the injection port 41. Moreover, since the flow of the mixture at the injection port 41 becomes a uniform axial flow, flashback into the first cylindrical body 4A can be prevented.

[0050] Furthermore, in this embodiment, the diameter of the first cylindrical body 4A narrows toward the injection port 41, so the flow velocity of the mixture of gas fuel and combustion air increases at the injection port 41. Therefore, flashback into the first cylindrical body 4A can be more effectively prevented.

[0051] In addition, in this embodiment, the leading edges 92 of the blades 91 in the second and subsequent stages in each static mixer 9 are sharp, which facilitates manufacturing of the static mixers 9 by additive manufacturing. Furthermore, the arrangement of the fuel injection holes 71 in each fuel distribution tube 7 as in this embodiment makes it possible to prevent the gas fuel from passing through the blow-through portion in the mixing flow path 8 that is formed by the sharp leading edges 92 of the blades 91 in the second and subsequent stages.

[0052] In the combustion zone 42 within the second cylindrical body 4B, the air-fuel mixture is combusted to generate a flame. However, without the second cylindrical body 4B, a circulating vortex is likely to form around the flame downstream of the first cylindrical body 4A. In contrast, if the combustion zone 42 downstream of the first cylindrical body 4A is surrounded by the second cylindrical body 4B as in this embodiment, such a circulating vortex is less likely to form within the second cylindrical body 4B. Furthermore, because the protective air flows along the inner surface of the second cylindrical body 4B, contact of the flame with the second cylindrical body 4B is also suppressed.

[0053] <Modifications> The present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the present disclosure.

[0054] For example, instead of the shaft 51 and the partition wall 52, a cylinder may be disposed inside the first cylindrical body 4A, and the mixing flow path 8 may be formed by a plurality of circular through-holes arranged circumferentially in the cylinder. However, if the shaft 51 and the partition wall 52 are employed as in the above embodiment and the cross-sectional shape of each mixing flow path 8 is fan-shaped, it is possible to ensure a larger total cross-sectional area of ​​the mixing flow path 8 than when the cross-sectional shape of the mixing flow path 8 is circular.

[0055] The fuel distribution tube 7 may be omitted, and the same number of fuel injection holes as the number of mixing passages 8 may be provided so as to be aligned in the circumferential direction on the outer peripheral surface of the fuel introducer 6. However, if the fuel distribution tube 7 including the fuel injection holes 71 is employed as in the above embodiment, the gas fuel can be injected at a plurality of positions distributed in the radial direction of the first cylindrical body 4A on the upstream side of each mixing passage 8.

[0056] In addition, in each static mixer 9, at least one blade 91 may be provided with a hole to improve mixing efficiency.

[0057] <Summary> In one aspect, the present disclosure provides a burner for burning a mixture of gas fuel and air to generate a flame, the burner comprising: a cylinder that forms an injection port for the mixture and surrounds a premixing zone including a plurality of mixing passages arranged in a circumferential direction; and a plurality of static mixers that mix the gas fuel and the air and are arranged in the plurality of mixing passages, respectively.

[0058] According to the above configuration, the gas fuel and air are mixed by the static mixers arranged in the circumferentially aligned mixing passages, which makes it possible to uniform the fuel concentration distribution in the mixture at the injection port, i.e., to achieve a sufficient degree of premixing at the injection port. Moreover, since the flow of the mixture at the injection port becomes a uniform axial flow, flashback into the cylinder can be prevented.

[0059] In a second aspect, the burner of the first aspect further comprises a shaft located at the center of the cylindrical body, and a plurality of partition walls that divide the space between the shaft and the cylindrical body into the plurality of mixing channels, each of which may have a sector-shaped cross section. With this configuration, the total cross-sectional area of ​​the mixing channels can be made larger than when the cross-sectional shape of the mixing channels is circular.

[0060] In a third aspect, the burner of the second aspect may further include a fuel inlet extending from the shaft toward the opposite side of the injection port and forming a fuel introduction chamber, and a plurality of fuel distribution tubes projecting radially from the fuel inlet so as to pass through the centers of adjacent partition walls when viewed in the axial direction of the cylindrical body, each of the plurality of fuel distribution tubes including a plurality of fuel injection holes. With this configuration, gas fuel can be injected at a plurality of positions distributed radially in the cylindrical body upstream of each mixing passage.

[0061] As a fourth aspect, in the third aspect, in each of the plurality of fuel distribution tubes, the diameter of the fuel injection hole farthest from the fuel introduction body among the plurality of fuel injection holes may be larger than the diameter of the fuel injection hole closest to the fuel introduction body. When the cross-sectional shape of the mixing flow channel is fan-shaped, the distance from the fuel distribution tube to the partition wall is short at the radially inner side of the cylinder, and the distance from the fuel distribution tube to the partition wall is long at the radially outer side of the cylinder. Therefore, if the diameter of the fuel injection hole farthest from the fuel introduction body is large, the gas fuel can be injected close to the partition wall at the radially outer side of the cylinder.

[0062] As a fifth aspect, in the third or fourth aspect, the cross-sectional shape of each of the plurality of fuel distribution tubes may be such that the length in the axial direction of the cylinder is longer than the width in the circumferential direction of the cylinder. With this configuration, it is possible to ensure a large opening area for air passage in the circumferential direction of the cylinder at the position where the fuel distribution tube is located, while ensuring a large wall thickness of the fuel distribution tube in the axial direction of the cylinder.

[0063] As a sixth aspect, in any of the first to fifth aspects, each of the static mixers may include a plurality of blades whose twist directions alternate, and the twist direction of the plurality of blades may be the same in the plurality of static mixers. If the twist directions of the blades of adjacent static mixers are opposite, there is a risk of a large imbalance in the fuel concentration after the mixture is combined immediately downstream of the static mixers. In contrast, if the twist direction of the blades of all static mixers is the same, it is possible to reduce the imbalance in the fuel concentration after the mixture is combined immediately downstream of the static mixers.

[0064] As a seventh aspect, in the sixth aspect, the blades other than the first blade from the upstream side of the plurality of blades may be pointed toward the torsion center of the upstream blade. With this configuration, the leading edges of the second and subsequent blades are sharp, which makes it easier to manufacture the static mixer by additive manufacturing.

[0065] As an eighth aspect, in the sixth or seventh aspect, the twist angle of each of the plurality of blades may be 180 degrees, the first upstream blade of the plurality of blades may have a leading edge extending in the radial direction of the cylindrical body, the second upstream blade of the plurality of blades may have a trailing edge perpendicular to the radial direction of the cylindrical body, and the third upstream blade of the plurality of blades may have a trailing edge extending in the radial direction of the cylindrical body. With this configuration, when viewed from the direction in which the twist centers of the blades extend, the trailing edge of the upstream blade and the leading edge of the downstream blade intersect in a cross shape. Therefore, each of the flows divided into two equal parts by the upstream blade is further divided into two equal parts by the leading edge of the downstream blade, thereby enabling efficient mixing of the gas fuel and air.

[0066] As a ninth aspect, in any of the third to fifth aspects, each of the plurality of static mixers includes a plurality of blades whose twist direction alternates, and the blades other than the first blade from the upstream side of the plurality of blades are pointed toward the twist center of the upstream blade, and the twist angle of each of the plurality of blades is 180 degrees, and the first blade from the upstream side of the plurality of blades has a leading edge extending in the radial direction of the cylindrical body, and the second blade from the upstream side of the plurality of blades has a trailing edge perpendicular to the radial direction of the cylindrical body, and The third-stage vane has a trailing edge extending radially from the cylindrical body, and the plurality of fuel injection holes of each of the plurality of fuel distribution tubes include a plurality of first fuel injection holes that inject fuel toward the direction in which the outer end of the leading edge of the first-stage vane twists, and a plurality of second fuel injection holes that inject fuel toward the direction in which the inner end of the leading edge of the first-stage vane twists. The second fuel injection holes may be located in a region inward from the center of the corresponding fuel distribution tube, and at least one of the plurality of first fuel injection holes may be located in a region outward from the center of the corresponding fuel distribution tube. With this configuration, the leading edges of the second-stage and subsequent vanes are sharp, facilitating the manufacture of a static mixer by additive manufacturing. Furthermore, the sharp leading edges of the second-stage and subsequent vanes can prevent gas fuel from passing through a blow-through portion in the mixing flow channel formed by the sharp leading edges of the second-stage and subsequent vanes. Furthermore, when viewed from the direction in which the torsion centers of the vanes extend, the trailing edge of the upstream vane and the leading edge of the downstream vane intersect in a cross shape. Therefore, each of the flows divided into two equal halves by the upstream blade is further divided into two equal halves by the leading edge of the downstream blade, thereby enabling efficient mixing of the gas fuel and air.

[0067] As a tenth aspect, in any one of the first to ninth aspects, the cylindrical body may have a diameter that narrows toward the injection port. With this configuration, the flow velocity of the air-fuel mixture at the injection port increases, making it possible to more effectively prevent flashback into the cylindrical body.

[0068] In an eleventh aspect, in any of the first to tenth aspects, the cylindrical body may be a first cylindrical body, and the burner may further include a second cylindrical body disposed outside the first cylindrical body and surrounding a combustion zone downstream of the first cylindrical body. In the combustion zone within the second cylindrical body, the air-fuel mixture is combusted to generate a flame. In the absence of the second cylindrical body, a circulating vortex is likely to form around the flame downstream of the first cylindrical body. In contrast, if the combustion zone downstream of the first cylindrical body is surrounded by the second cylindrical body as in the above configuration, such a circulating vortex is less likely to form within the second cylindrical body.

[0069] From another aspect, the present disclosure provides a combustor including a plurality of burners according to any one of the first to eleventh aspects.

[0070] REFERENCE SIGNS LIST 1 combustor 3 burner 4A first cylindrical body 4B second cylindrical body 40 premixing zone 41 injection port 42 combustion zone 51 shaft body 52 partition wall 6 fuel introduction body 61 fuel introduction chamber 7 fuel distribution tube 71 fuel injection port 71A first fuel injection port 71B second fuel injection port 8 mixing flow path 9 static mixer 90 twist center 91, 91A, 91B, 91C blade 92 leading edge 92a outer end 92b inner end 93 trailing edge

Claims

1. A burner for burning a mixture of gas fuel and air to generate a flame, comprising: a cylinder that forms an injection port for the mixture and surrounds a premixing zone including a plurality of mixing passages arranged in the circumferential direction; and a plurality of static mixers that mix the gas fuel and the air, each of which is arranged in one of the plurality of mixing passages.

2. A burner as described in claim 1, further comprising: a shaft located at the center of the cylinder; and a plurality of partition walls that divide the space between the shaft and the cylinder into the plurality of mixing passages, each of the plurality of mixing passages having a sector-shaped cross section.

3. A burner as described in claim 2, further comprising: a fuel introduction body that forms a fuel introduction chamber and extends from the shaft body toward the opposite side of the injection port; and a plurality of fuel distribution tubes that project radially from the fuel introduction body so as to pass through the centers of adjacent partition walls when viewed from the axial direction of the cylindrical body, each of the plurality of fuel distribution tubes including a plurality of fuel injection holes.

4. A burner as described in claim 3, wherein in each of said plurality of fuel distribution tubes, the diameter of the fuel injection hole farthest from said fuel introduction body among said plurality of fuel injection holes is larger than the diameter of the fuel injection hole nearest to said fuel introduction body.

5. A burner according to claim 3 or 4, wherein the cross-sectional shape of each of the plurality of fuel distribution tubes is such that the length in the axial direction of the cylinder is longer than the width in the circumferential direction of the cylinder.

6. A burner as claimed in any one of claims 1 to 4, wherein each of the plurality of static mixers includes a plurality of blades whose twist directions alternate, and the twist directions of the plurality of blades are the same in the plurality of static mixers.

7. A burner according to claim 6, wherein the blades other than the first stage from the upstream side among said plurality of blades are pointed toward the twist center of the upstream blade.

8. A burner as described in claim 6, wherein the twist angle of each of the plurality of blades is 180 degrees, the first blade from the upstream side of the plurality of blades has a leading edge extending in the radial direction of the cylinder, the second blade from the upstream side of the plurality of blades has a trailing edge perpendicular to the radial direction of the cylinder, and the third blade from the upstream side of the plurality of blades has a trailing edge extending in the radial direction of the cylinder.

9. Each of the plurality of static mixers includes a plurality of blades whose twist direction alternates, and all of the plurality of blades except the first blade from the upstream side are pointed toward the twist center of the upstream blade, and the twist angle of each of the plurality of blades is 180 degrees, and the first blade from the upstream side of the plurality of blades has a leading edge extending in the radial direction of the cylinder, the second blade from the upstream side of the plurality of blades has a trailing edge perpendicular to the radial direction of the cylinder, and the third blade from the upstream side of the plurality of blades has a trailing edge extending in the radial direction of the cylinder, and the plurality of fuel injection holes of each of the plurality of fuel distribution tubes include a plurality of first fuel injection holes that inject fuel in the twisting direction of the outer ends of the leading edges of the first blades and a plurality of second fuel injection holes that inject fuel in the twisting direction of the inner ends of the leading edges of the first blades, 4. The burner according to claim 3, wherein the plurality of second fuel injection holes are located in a region inward from a center of the corresponding fuel distribution tube, and at least one of the plurality of first fuel injection holes is located in a region outward from a center of the corresponding fuel distribution tube.

10. A burner according to any one of claims 1 to 4, wherein the cylindrical body has a diameter that narrows toward the injection port.

11. A burner as claimed in any one of claims 1 to 4, wherein the cylinder is a first cylinder, and further comprising a second cylinder arranged outside the first cylinder and surrounding a combustion zone downstream of the first cylinder.

12. A combustor comprising a plurality of burners according to any one of claims 1 to 4.

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