Premixed combustion furnace, fuel injection device and gas turbine

Abstract

This invention provides a premixed combustion furnace, comprising: an outer tube having an inlet opening on a first side in the axial direction and an outlet opening on a second side in the axial direction; an inner tube, formed as a cylinder extending in the axial direction, spaced apart from the inner side of the outer tube and forming a thin-film airflow path between the inner and outer tubes for thin-film airflow; and a support extending from the inner wall surface of the outer tube toward the inner side to support the inner tube. The end of the inner tube on the first side is disposed further to the second side than the inlet opening of the outer tube, and the end of the inner tube on the second side is disposed further to the first side than the outlet opening of the outer tube. A fuel injection path is formed in the outer tube, the support, and the inner tube for injecting fuel from the outside of the outer tube through the inside of the support to the inside of the inner tube.

Description

Technical Field

[0001] This invention relates to a premixed combustion furnace, a fuel injection device, and a gas turbine.

[0002] This application claims priority based on Japanese Patent Application No. 2021-025565, filed on February 19, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] In combustors such as gas turbines, a technique known as premixed combustion is employed to reduce nitrogen oxide emissions. Patent Document 1 describes a premixed combustion furnace for gas turbines that can suppress flashback into the flow path when using highly reactive fuels with high combustion rates, such as hydrogen. In this premixed combustion furnace, fuel flows from the fuel chamber into the airflow in the pipe flow path and mixes with it, then air flows into the air chamber in a manner that crosses with the mixture.

[0004] Previous technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-57929 Summary of the Invention

[0007] The technical problem to be solved by the invention

[0008] In the premixed combustion furnace described in Patent Document 1, the flow velocity of the mixed gas flowing in the tube flow path slows down near the inner wall of the tube. On the other hand, as in Patent Document 1, when fuel flows in in a manner that crosses the airflow relative to the tube flow path, the fuel concentration near the inner wall of the tube may sometimes become high. Therefore, the combustion rate of the fuel may be higher than the flow velocity near the inner wall of the tube, and a flashback of the flame upward in the tube flow path may occur.

[0009] The purpose of this invention is to provide a premixed combustion furnace, a fuel injection device, and a gas turbine that can suppress flashback.

[0010] means for solving technical problems

[0011] To address the aforementioned issues, the premixed combustion furnace of the present invention comprises: an outer tube having an inlet opening on a first side in an axial direction extending along the axis and an outlet opening on a second side in the same axial direction; an inner tube formed as a cylinder extending along the axial direction, disposed at intervals on the inner side of the outer tube, and forming a thin-film airflow path for thin-film airflow between the inner tube and the outer tube; and a support extending inward from the inner wall surface of the outer tube to support the inner tube, wherein the end of the inner tube on the first side is disposed further to the second side than the inlet opening of the outer tube, and the end of the inner tube on the second side is disposed further to the first side than the outlet opening of the outer tube; and a fuel injection path is formed in the outer tube, the support, and the inner tube for injecting fuel from the outside of the outer tube through the inside of the support to the inside of the inner tube.

[0012] Invention Effects

[0013] The above method can suppress the occurrence of flashbacks. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view schematically illustrating the structure of a gas turbine according to the first embodiment of the present invention.

[0015] Figure 2 This is a cross-sectional view of the burner in the first embodiment of the invention.

[0016] Figure 3 This is a cross-sectional view of the premixed combustion furnace according to the first embodiment of the present invention.

[0017] Figure 4 yes Figure 3 Sectional view IV-IV of the support.

[0018] Figure 5 This is a diagram showing the premixed combustion furnace as viewed from the axial direction.

[0019] Figure 6 It is a graph with the vertical axis set as the fuel concentration of the inner wall surface of the inner tube and the inner wall surface of the outer tube, which is further downstream of the inner tube on the axis, and the horizontal axis set as the axial direction of the premixed combustion furnace.

[0020] Figure 7 The premixed combustion furnace according to the second embodiment of the present invention is related to... Figure 3 The corresponding sectional view.

[0021] Figure 8 This is a cross-sectional view of a premixed combustion furnace, representing a first modified embodiment of the present invention.

[0022] Figure 9This is a cross-sectional view of a premixed combustion furnace, representing a second modified embodiment of the present invention. Detailed Implementation

[0023] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0024] <First Implementation Method>

[0025] <<Structure of a Gas Turbine>>

[0026] Figure 1 This is a cross-sectional view schematically illustrating the structure of a gas turbine according to the first embodiment of the present invention.

[0027] like Figure 1 As shown, the gas turbine 10 includes: a compressor 20 for compressing air A; a plurality of burners 40 for generating combustion gas G by burning fuel in the air compressed by the compressor 20; and a turbine 30 driven by the combustion gas G.

[0028] The compressor 20 includes: a compressor rotor 21 that rotates about a rotor axis Lr; a compressor housing 25 that rotatably covers the compressor rotor 21; and a plurality of fixed blade rows 26. Hereinafter, the direction in which the rotor axis Lr extends is defined as the rotor axis direction Da, one side of this rotor axis direction Da is defined as the upstream side Dau, and the other side is defined as the downstream side Dad. Furthermore, the circumferential direction centered on the rotor axis Lr is simply referred to as the circumferential direction Dc, and the direction perpendicular to the rotor axis Lr is defined as the radial direction Dr. Additionally, the side of the radial direction Dr closest to the rotor axis Lr is defined as the radially inner side Dri, and the opposite side is defined as the radially outer side Dro.

[0029] The compressor rotor 21 has: a rotor shaft 22 extending along the rotor axis Lr in the rotor axis direction Da; and a plurality of rotating blade rows 23 mounted on the rotor shaft 22. The plurality of rotating blade rows 23 are arranged along the rotor axis direction Da. Each rotating blade row 23 is composed of a plurality of rotating blades arranged circumferentially Dc. On the downstream side Dad of each of the plurality of rotating blade rows 23, any one of a plurality of fixed blade rows 26 is disposed. Each fixed blade row 26 is disposed inside the compressor housing 25. Each fixed blade row 26 is composed of a plurality of fixed blades arranged circumferentially Dc. The annular space between the radially outer side Dro of the rotor shaft 22 and the radially inner side Dri of the compressor housing 25, and in the region where fixed blades and rotating blades are disposed in the rotor axis direction Da, forms an air compression flow path where air flows and is compressed simultaneously.

[0030] A turbine 30 is positioned downstream of the compressor 20 on the axis of rotation, at point Da. The turbine 30 includes: a turbine rotor 31 that rotates about a rotor axis Lr; a turbine housing 35 that rotatably covers the turbine rotor 31; and multiple fixed blade rows 36. The turbine rotor 31 includes: a rotor shaft 32 extending along the rotor axis Lr in the rotor axial direction Da; and multiple rotating blade rows 33 mounted on the rotor shaft 32. The multiple rotating blade rows 33 are arranged along the rotor axial direction Da. Each rotating blade row 33 consists of multiple rotating blades arranged circumferentially at point Dc.

[0031] On the upstream side (Dau) of each of the multiple rotating blade rows 33, any one of the multiple fixed blade rows 36 is arranged. Each fixed blade row 36 is located inside the turbine housing 35. Each fixed blade row 36 consists of multiple fixed blades arranged circumferentially (Dc). The annular space between the radially outer side (Dro) of the rotor shaft 32 and the radially inner side (Dri) of the turbine housing 35, and in the rotor axial direction (Da), where fixed blades and rotating blades are arranged, becomes a combustion gas flow path for the combustion gas G from the combustor 40 to flow.

[0032] The compressor rotor 21 and the turbine rotor 31 are located on the same rotor axis Lr and are connected to each other to form the gas turbine rotor 11. This gas turbine rotor 11 may include, for example, a rotor connected to a generator GEN. The gas turbine 10 also includes a cylindrical intermediate housing 16 centered on the rotor axis Lr.

[0033] An intermediate housing 16 is disposed between the compressor housing 25 and the turbine housing 35 along the rotor axis direction Da. The compressor housing 25 and the turbine housing 35 are connected via the intermediate housing 16. The compressor housing 25, the intermediate housing 16, and the turbine housing 35 are interconnected to form a gas turbine housing 15. Compressed air Acom from the compressor 20 flows into the intermediate housing 16. A plurality of burners 40 are disposed in the intermediate housing 16.

[0034] <<Structure of the Burner>>

[0035] Figure 2 This is a cross-sectional view of the burner in the first embodiment of the invention. Additionally, in Figure 2 The detailed internal structure of the burner 40 is omitted from the illustration.

[0036] like Figure 2 As shown, the burner 40 has a combustion chamber 50 and a fuel injection device 60.

[0037] The combustion chamber 50 generates high-temperature, high-pressure combustion gas G from the mixture Gm injected from the fuel injection device 60 through combustion (in other words, premixed combustion). The combustion chamber 50 then delivers the generated high-temperature, high-pressure combustion gas G into the combustion gas flow path of the turbine 30. In this first embodiment, the combustion chamber 50 is disposed within the intermediate housing 16.

[0038] Fuel injection device 60 mixes compressed air Acom with fuel F (reference) Figure 1 The mixture Gm is injected into the combustion chamber 50. The fuel injection device 60 includes multiple premixed combustion furnaces 61A, a shell 62, and a fuel chamber 63 (described later). The fuel F of the burner 40 in this first embodiment can be a highly reactive fuel with a high combustion rate, such as hydrogen. Furthermore, the direction in which the axis At of the burner 40 extends is referred to as the burner axis direction Dt. Additionally, the burner 40 may also include a pilot burner (not shown).

[0039] <<Structure of a Premixed Combustion Furnace>>

[0040] Figure 3 This is a cross-sectional view of the premixed combustion furnace according to the first embodiment of the present invention, for example, it is... Figure 2 An enlarged view of the part enclosed by the dashed line. Figure 4 yes Figure 3 Sectional view IV-IV of the support. Figure 5 yes Figure 3 The image shows a VV sectional view of the premixed combustion furnace. It is a view of the premixed combustion furnace as seen from the axial direction.

[0041] The premixed combustion furnace 61A mixes compressed air Acom supplied from compressor 20 with fuel F supplied from fuel line 45. Figure 3 As shown, the premixed combustion furnace 61A has an outer tube 64, an inner tube 65, and a support column 66.

[0042] like Figure 2 , Figure 3As shown, the outer tube 64 has an inlet opening 67 on the first side of the burner axial direction Dt, i.e., the upstream side Dtu, and an outlet opening 68 on the second side of the burner axial direction Dt, i.e., the downstream side Dtd. In this first embodiment, the outer tube 64 has a cylindrical internal space 69 formed on its inner side, centered on a central axis O parallel to the axis At. The lengths of the burner axial direction Dt of the outer tubes 64 of the plurality of premixed combustion furnaces 61A in this first embodiment are all the same. Furthermore, the positions of the burner axial direction Dt of these outer tubes 64 are all the same. Hereinafter, the direction in which the central axis O extends from the internal space 69 of the outer tube 64 is designated as the axial direction Do. The first side of the axial direction Do is designated as the upstream side Dou, and the second side as the downstream side Dod. Furthermore, the circumferential direction centered on the central axis O is simply referred to as the circumferential direction Doc, and the direction perpendicular to the central axis O is designated as the radial direction Dor.

[0043] like Figure 3 As shown, the inner tube 65 is spaced apart from each of the plurality of outer tubes 64 on their inner sides. The inner tube 65 is formed into a cylindrical shape extending along the axial direction Do. A thin-film air flow path 71 for thin-film air flow Af is formed between the inner tube 65 and the outer tubes 64. The inner tube 65 illustrated in this first embodiment is formed into a cylindrical shape with a constant thickness and centered on the central axis O. Thus, in this first embodiment, a thin-film air flow path 71 with a constant radial diameter Do is formed between the outer peripheral surface 65a of the inner tube 65 and the inner peripheral surface 64a of the outer tube 64, except for the portion forming the support 66. For example, the radial diameter S of the thin-film air flow path 71 can be set to about 10% of the inner diameter of the outer tube 64.

[0044] The end 65c of the inner tube 65 on the upstream side of the axis Dou is positioned further downstream of the axis Dod than the inlet opening 67 of the outer tube 64. Furthermore, the end 65d of the inner tube 65 on the downstream side of the axis Dod is positioned further upstream of the axis Dou than the outlet opening 68 of the outer tube 64. In the premixed combustion furnace 61A illustrated in this first embodiment, the distance L2 between the end 65d of the downstream side of the axis Dod and the outlet opening 68 is greater than the distance L1 between the end 65c of the upstream side of the axis Dou and the inlet opening 67.

[0045] In this first embodiment, the inner tube 65 has a tapered surface 72 at its end 65d on the downstream side of the axis Dod. The tapered surface 72 is inclined in such a way that the cross-sectional area of ​​the inner flow path 73 formed on the radial Dor side of the inner tube 65 toward the downstream side of the axis Dod increases.

[0046] like Figure 3 , Figure 5As shown, the support column 66 extends inward from the inner circumferential surface 64a of the outer tube 64 to support the inner tube 65. In other words, the support column 66 is configured to transversely cut the thin-film airflow path 71 in the radial direction (Doc) and connect the inner circumferential surface 64a of the outer tube 64 and the outer circumferential surface 65a of the inner tube 65. In this first embodiment, multiple supports column 66 are spaced apart in the circumferential direction (Doc). Figure 5 In the example, there is a case where four pillars 66 are configured in a way that makes them equally spaced on the circumferential Doc.

[0047] like Figure 4 As shown, the cross-sectional shape of the support 66 is blade-shaped. More specifically, the cross-sectional shape of the support 66 is a symmetrical blade, wherein a first surface 66a facing the first side in the circumferential direction Doc and a second surface 66b facing the second side are symmetrically formed, and the centerline Lc of the circumferential direction Doc coincides with the blade chord. Then, the centerline Lc of this symmetrical blade extends along the axial direction Do. As described above, by having a symmetrical blade-shaped cross-sectional shape, the rotational component imparted by the support 66 to the airflow in the thin-film airflow path 71 can be suppressed.

[0048] like Figure 3 As shown, in this first embodiment, the upstream end 65c of the inner tube 65 extends further upstream than the end 66c of the support 66. Furthermore, the downstream end 66d of the support 66 is positioned closer to the upstream end 66c than the end 65d of the inner tube 65.

[0049] like Figure 3 As shown, the fuel chamber 63 is disposed on the housing 62 (reference). Figure 2 The outer side of the inner and outer pipes 64. A fuel line 45 (see reference) is connected to the fuel chamber 63. Figure 1 Fuel F is supplied from fuel line 45 to fuel chamber 63. Additionally, as... Figure 1 As shown, a fuel flow regulating valve 46 is provided in the fuel line 45, which regulates the flow rate of fuel F supplied to the fuel chamber 63. In this first embodiment, the fuel chamber 63 is formed at least on the outer side of the radial direction of the support 66.

[0050] A fuel injection path 74 is formed in the outer pipe 64, the support column 66, and the inner pipe 65. The fuel injection path 74 injects fuel F from the outside of the outer pipe 64, through the inside of the support column 66, into the inner flow path 73 inside the inner pipe 65. More specifically, in this first embodiment, the fuel injection path 74 radially penetrates the outer pipe 64, the support column 66, and the inner pipe 65. Through this fuel injection path 74, the fuel chamber 63 adjacent to the outer pipe 64 and the inner flow path 73 of the inner pipe 65 are connected, and the fuel F in the fuel chamber 63 is injected through the fuel injection path 74. Figure 3 As shown by the dashed line, fuel is injected into the inner flow path 73 of the inner tube 65. Here, the case where the fuel injection flow path 74 extends radially (Dor) has been described, but the direction of extension of the fuel injection flow path 74 is not limited to radial (Dor). The direction of extension of the fuel injection flow path 74 is... Figure 3 In the sectional view, the direction intersecting the central axis 0 is sufficient.

[0051] <<Length of outer and inner tubes>>

[0052] Figure 6 It is a graph with the vertical axis set as the fuel concentration of the inner circumferential surface of the inner tube and the inner circumferential surface of the outer tube, which is further downstream of the inner tube from the axis, and the horizontal axis set as the axial direction of the premixed combustion furnace.

[0053] In the premixed combustion furnace 61A described above, compressed air Acom flows in from the upstream side of the axis (Dou). Specifically, compressed air Acom flows in from the inlet opening 67 of the outer tube 64 and is split into a thin-film air flow path 71 located outside the inner tube 65 and an inner flow path 73 located inside the inner tube 65. At this time, compressed air Acom is split into two flow rates (volume flow rates) corresponding to the ratio of the cross-sectional areas of the thin-film air flow path 71 and the inner flow path 73. A portion of the compressed air Acom flowing into the thin-film air flow path 71 (in other words, thin-film air Af) flows in the thin-film air flow path 71 toward the downstream side of the axis (Dod). On the other hand, the remaining portion of the compressed air Acom flowing into the inner flow path 73 (in other words, the main flow) mixes with the fuel F injected from the fuel injection flow path 74 to form a mixture Gm. In this first embodiment, the injection of fuel F becomes a so-called crossflow, injected in a direction that crosses the flow of the inner flow path 73.

[0054] Near the inner circumferential surface 65b of the inner tube 65 and near the inner circumferential surface 64a of the outer tube 64, flows sometimes occur with a velocity lower than the combustion velocity (in other words, the flame reaction velocity) of the gas mixture Gm due to the reduced velocity caused by contact with the inner circumferential surfaces 64a and 65b. Here, a velocity lower than the combustion velocity refers to, for example, in the case of a combustible fluid flow, a velocity that causes the flame to travel upstream. Hereinafter, flows with velocities lower than the combustion velocity of the gas mixture Gm due to the reduced velocity caused by contact with the inner circumferential surfaces 64a and 65b will be simply referred to as flows in contact with the inner circumferential surface 64a or flows in contact with the inner circumferential surface 65b.

[0055] In such a premixed combustion furnace 61A, the more the fuel F injected is directed downstream of the axis (Dod), the more it is mixed with the compressed air (Acom), such as... Figure 6 As shown, the fuel concentration flowing in contact with the inner circumferential surface 65b of the inner tube 65 gradually increases. In this first embodiment, the length of the inner tube 65 in the axial direction Do is formed such that the fuel concentration flowing in contact with the inner circumferential surface 65b of the inner tube 65 becomes a sufficiently low concentration (hereinafter referred to as the reference concentration) that makes it impossible for a flame to be maintained in the airflow. Figure 6 (The following is represented by a single-dot dash.)

[0056] From the downstream side of the axis of the inner tube 65, at the end 65d of Dod (in Figure 6 The mixed gas Gm flowing from the inner tube outlet (inner tube 65) towards the downstream side Dod flows in the flow path (internal space 69) inside the outer tube 64 towards the downstream side Dod. Here, around the mixed gas Gm that just flows out from the end 65d of the inner tube 65, the thin film air Af flowing out from the thin film air flow path 71 flows. Then, the thin film air Af flows in the axial direction Do towards the outlet opening 68 of the outer tube 64 (inner tube 65) from the end 65d of the inner tube 65 downstream side Dod. Figure 6 The middle section (outlet of the outer pipe) mixes with the mixed gas Gm, and its fuel concentration gradually increases. That is, as... Figure 6 As shown, the fuel concentration flowing in contact with the inner circumferential surface 64a of the outer pipe 64 is from the end 65d of Dod on the downstream side of the axis (in Figure 6 The position of the outer pipe 64 (the outlet of the inner pipe) gradually rises towards the downstream side of the axis. In this first embodiment, the length of the outer pipe 64 in the axial direction of Do is formed such that the flow fuel concentration in contact with the inner circumferential surface 64a of the outer pipe 64 is below the reference concentration.

[0057] <<Effects>>

[0058] The premixed combustion furnace 61A of the first embodiment described above includes: an outer tube 64 having an inlet opening 67 on the upstream side Dou of the axis and an outlet opening 68 on the downstream side Dod of the axis; an inner tube 65, formed as a cylinder extending along the axial direction Do, disposed at intervals inside the outer tube 64, and forming a thin-film air flow path 71 for thin-film air Af to flow between the inner tube 65 and the outer tube 64; and a support 66 extending inward from the inner circumferential surface 64a of the outer tube 64 to support the inner tube 65. The end 65c of the inner tube 65 on the upstream side Dou is disposed further downstream on the axis Dod than the inlet opening 67 of the outer tube 64, and the end 65d of the inner tube 65 on the downstream side Dod is disposed further upstream on the axis Dou than the outlet opening 68 of the outer tube 64. Furthermore, a fuel injection path 74 is formed in the outer pipe 64, the support column 66, and the inner pipe 65, which injects fuel F from the outside of the outer pipe 64 through the inside of the support column 66 to the inside of the inner pipe 65.

[0059] According to the premixed combustion furnace 61A with this structure, a thin-film air flow path 71 is formed by arranging an inner tube 65 inside the outer tube 64, allowing the thin-film air Af to flow along the inner circumferential surface 64a of the outer tube 64, which is located downstream of the inner tube 65 on the axis. This suppresses the rise in fuel concentration in the flow contacting the inner circumferential surface 64a of the outer tube 64. Therefore, even when the flow velocity in contact with the inner circumferential surface 64a of the outer tube 64 is lower than the combustion velocity, the upward flashback of the flame in the flow contacting the inner circumferential surface 64a of the outer tube 64 can be suppressed.

[0060] Furthermore, according to the aforementioned premixed combustion furnace 61A, since the end 65c of the inner tube 65 on the upstream side of the axis Dou is positioned further downstream of the axis Dod than the inlet opening 67 of the outer tube 64, the flow of compressed air Acom flowing in from the inlet opening 67 of the outer tube 64 is not obstructed, and the compressed air Acom can be stably diverted to the thin-film air flow path 71 and the inner flow path 73. Moreover, since the end 65d of the inner tube 65 on the downstream side of the axis Dod is positioned further upstream of the axis Dou than the outlet opening 68 of the outer tube 64, the upward movement of the flame in contact with the inner circumferential surface 65b of the inner tube 65 can be suppressed.

[0061] Furthermore, according to the premixed combustion furnace 61A described above, since the fuel injection flow path 74 is formed inside the outer tube 64, the support column 66, and the inner tube 65, the fuel F supplied to the fuel chamber 63, etc., outside the outer tube 64 can be injected in a manner that crosses the flow path 73 from the inner circumferential surface 65b of the inner tube 65. Therefore, there is no need to form a dedicated piping for guiding the fuel injection flow path 74, and the fuel injection flow path 74 can be formed by effectively utilizing the interior of the support column 66 that supports the inner tube 65.

[0062] The outer tube 64 of the premixed combustion furnace 61A of the first embodiment described above is formed such that the length of the flow that contacts the inner circumferential surface 64a of the outer tube 64 during the flow from the inlet opening 67 through the thin film air flow path 71 to the outlet opening 68 has a fuel concentration that is below the reference concentration.

[0063] Therefore, the fuel concentration in the flow contacting the inner circumferential surface 64a of the outer pipe 64 is below the reference concentration, which can suppress combustion in the flow contacting the inner circumferential surface 64a of the outer pipe 64. As a result, the generation of flame flashback in the flow contacting the inner circumferential surface 64a of the outer pipe 64 can be suppressed.

[0064] Furthermore, the inner tube 65 of the premixed combustion furnace 61A of the first embodiment described above is formed such that the fuel concentration in the flow that contacts the inner circumferential surface 65b of the inner tube 65 in the flow flowing out from the end 65d of the downstream side Dod of the axis of the inner tube 65 is below the reference concentration.

[0065] Therefore, the fuel concentration in the flow contacting the inner circumferential surface 65b of the inner tube 65 is below the reference concentration, which can suppress combustion in the flow contacting the inner circumferential surface 65b of the inner tube 65. As a result, the generation of flame flashback in the flow contacting the inner circumferential surface 65b of the inner tube 65 can be suppressed.

[0066] Furthermore, the support column 66 of the premixed combustion furnace 61A of the first embodiment described above is in the shape of a blade cross section.

[0067] Therefore, the flow resistance of the thin film air Af flowing in the axial direction Do in the thin film air flow path 71 can be reduced, thus suppressing the decrease in the flow velocity of the thin film air Af.

[0068] Furthermore, the premixed combustion furnace 61A of the first embodiment described above has a conical surface 72 at the end 65d of the downstream side Dod of the inner tube 65, which is inclined in such a way that the cross-sectional area of ​​the inner flow path 73 increases as it moves toward the downstream side Dod of the axis.

[0069] Therefore, when a tapered surface 72 needs to be provided at the end 65d of the Dod on the downstream side of the axis due to the manufacturing of the inner tube 65, the expansion of the cross-sectional area of ​​the thin film air flow path 71 can be suppressed, thereby restoring the static pressure of the thin film air Af and reducing the flow velocity.

[0070] Furthermore, the premixed combustion furnace 61A of the first embodiment described above contains hydrogen as fuel F.

[0071] According to the premixed combustion furnace 61A described above, even when using highly reactive fuels containing hydrogen and with high combustion rates, flashback can be effectively suppressed.

[0072] Furthermore, the fuel injection device 60 of the first embodiment includes: a plurality of premixed combustion furnaces 61A, a housing 62 supporting the premixed combustion furnaces 61A, and a fuel chamber 63 disposed inside the housing 62 and outside the outer tube 64.

[0073] According to the fuel injection device 60 described above, damage caused by flashback can be suppressed by having the premixed combustion furnace 61A described above.

[0074] Furthermore, the gas turbine 10 of the first embodiment includes: a compressor 20 that generates compressed air Acom; a burner 40 having the aforementioned fuel injection device 60 and a combustion chamber 50 that generates combustion gas G by burning the mixture Gm injected from the fuel injection device 60; and a turbine 30 driven by the combustion gas G generated in the burner 40.

[0075] According to this gas turbine 10, damage to the burner 40 can be suppressed, and the reliability of the gas turbine 10 can be improved.

[0076] <Second Implementation Method>

[0077] Next, a second embodiment of the present invention will be described based on the accompanying drawings. In the second embodiment described below, only the structure of the first embodiment described above differs from that of the premixed combustion furnace. Therefore, while describing the parts that are the same as those in the first embodiment using the same reference numerals, repeated descriptions are omitted (the same applies to the first and second modifications described later).

[0078] <<Structure of a Premixed Combustion Furnace>>

[0079] Figure 7 The premixed combustion furnace according to the second embodiment of the present invention is related to... Figure 3 The corresponding sectional view.

[0080] like Figure 7 As shown, the premixed combustion furnace 61B of the second embodiment mixes compressed air Acom supplied from the compressor 20 with fuel F supplied from the fuel line 45. The premixed combustion furnace 61B includes an outer pipe 64B, an inner pipe 65B, and a support 66.

[0081] Similar to the first embodiment, the outer tube 64B of this second embodiment has an inlet opening 67 on the upstream side of the axis and an outlet opening 68 on the downstream side of the axis. The outer tube 64B includes an outer tube body 81, an outlet cross-section reduction portion 82, and an outlet end 83. In this embodiment, the outer tube body 81 has a cylindrical internal space 84 formed on its inner side, centered on a central axis O parallel to the axis At. Furthermore, the cross-sectional shape of the internal space 84 of the outer tube body 81 is not limited to a circle.

[0082] The outlet section reduction portion 82 is formed on the downstream side Dod of the axis of the outer tube body 81. The outlet section reduction portion 82 causes the cross-sectional area (in other words, the flow path cross-sectional area) of the internal space 69 of the outer tube 64B to gradually decrease towards the outlet opening 68. In this second embodiment, the outlet section reduction portion 82 causes the flow path cross-sectional area of ​​the outer tube 64B to be reduced at a constant tilt angle on the downstream side Dod to an inner diameter r2 that is the same as the inner diameter r1 of the inner tube 65B.

[0083] The outlet end 83 is formed on the downstream side Dod of the outlet cross-section reduction portion 82. The outlet end 83 connects the outlet cross-section reduction portion 82 and the outlet opening 68, and forms a constant flow path cross-sectional area throughout the entire region in the axial direction Do. In this second embodiment, the flow path cross-sectional area (in other words, the inner diameter) of the outlet end 83 is the same as the flow path cross-sectional area (in other words, the inner diameter) of the inner flow path 73 of the inner tube 65B.

[0084] Similar to the first embodiment, the inner tube 65B is arranged at a distance from the outer tube 64B. The inner tube 65B is formed as a cylinder extending along the axial direction Do, and a thin-film air flow path 71 for the flow of thin-film air Af is formed between it and the outer tube 64B. The upstream end 65c of the inner tube 65B is positioned further downstream than the inlet opening 67 of the outer tube 64B. Furthermore, the downstream end 65d of the inner tube 65B is positioned further upstream than the outlet opening 68 of the outer tube 64B. In this second embodiment, similar to the first embodiment, the distance between the downstream end 65d and the outlet opening 68 is greater than the distance between the upstream end 65c and the inlet opening 67 along the axial direction Do.

[0085] In this second embodiment, the downstream end 65d of the inner tube 65B is formed to overlap with a portion of the upstream end 65d of the outlet section reduction portion 82 in the axial direction Do. A chamfer 85 is formed at the downstream end 65d of the inner tube 65B, parallel to the inner wall surface 82a of the outlet section reduction portion 82. By forming this chamfer 85, the cross-sectional area of ​​the thin-film airflow path 71 (in other words, the radial dimension S of Do) can be kept constant even near the end 65d of the inner tube 65B.

[0086] <<Effects>>

[0087] The outer tube 64B of the premixed combustion furnace 61B of the second embodiment described above has an outlet cross-section reduction portion 82 that gradually decreases in cross-sectional area toward the outlet opening 68.

[0088] According to this premixed combustion furnace 61B, in addition to the effects of the first embodiment described above, the flow path cross-sectional area of ​​the outer tube 64B can be gradually reduced by the outlet cross-section reduction portion 82, thereby suppressing the deceleration of the mainstream and thin-film air Af flowing out from the inner flow path 73 of the inner tube 65B. Furthermore, since the flow path cross-sectional area of ​​the inner flow path 73 is the same as that of the outlet end 83, the mainstream does not decelerate. Therefore, the development of vortices caused by the step formed at the end 65d of the inner tube 65B downstream of the axis Dod can be suppressed.

[0089] <First variation of the implementation method>

[0090] Next, a first variation of the embodiments of the present invention will be described based on the accompanying drawings.

[0091] In the premixed combustion furnaces 61A and 61B of the first and second embodiments described above, a structure was described in which a hydrogen-containing fuel F was injected from the fuel injection path 74 and mixed. However, the premixed combustion furnace 61C can also be configured to premix two or more fuels with different combustion rates with compressed air Acom. Figure 8 This is a cross-sectional view of a premixed combustion furnace in a first variation of an embodiment of the present invention.

[0092] like Figure 8 As shown, the premixed combustion furnace 61C in the first modification, in addition to the structure of the premixed combustion furnace 61A of the first embodiment described above, is also configured to inject a fuel (hereinafter simply referred to as low-reactivity fuel F2) whose combustion rate is lower than that of fuel F, which is a highly reactive fuel containing hydrogen. This first modification of the premixed combustion furnace 61C is configured to selectively inject fuel F and low-reactivity fuel F2, but it is also possible to inject fuel F and low-reactivity fuel F2 simultaneously. For example, a fuel containing methane can be cited as the low-reactivity fuel F2.

[0093] The fuel injection device 60 of the first modified example has a first fuel chamber 63A for storing fuel F and a second fuel chamber 63B for storing low-reactivity fuel F2 between the outer tube 64 and the housing 62.

[0094] The premixed combustion furnace 61C includes a plurality of supports 66 spaced apart in the axial direction Do. In this first modification, the premixed combustion furnace 61C includes first supports 66A and second supports 66B arranged spaced apart in the axial direction Do. Furthermore, in this first modification, a plurality of first supports 66A are provided spaced apart in the circumferential direction Doc. Similarly, a plurality of second supports 66B are provided spaced apart in the circumferential direction Doc. Additionally, the positions of the first supports 66A and the second supports 66B in the circumferential direction Doc can be set to be the same as each other.

[0095] A fuel injection path 74 is formed in the outer pipe 64, the support column 66, and the inner pipe 65 to inject fuel from the outside of the outer pipe 64 through the inside of the support column 66 to the inside of the inner pipe 65. In this first modification, a first fuel injection path 74A is formed in the outer pipe 64, the first support column 66A, and the inner pipe 65, and a second fuel injection path 74B is formed in the outer pipe 64, the second support column 66B, and the inner pipe 65. The first fuel injection path 74A connects the first fuel chamber 63A with the inner flow path 73 of the inner pipe 65, and the second fuel injection path 74B connects the second fuel chamber 63B with the inner flow path 73 of the inner pipe 65.

[0096] According to the premixed combustion furnace 61C in the first modified example described above, since a second fuel injection path 74B is formed on the upstream side of the axis, which is further upstream than the first fuel injection path 74A, when using low-reactive fuel F2, it can be injected from the upstream side of the axis and mixed with compressed air Acom. Therefore, the distance from the second fuel injection path 74B to the outlet opening 68 can be increased, thereby suppressing flashback, promoting the mixing of compressed air Acom and low-reactive fuel F2, and reducing the amount of nitrogen oxides produced.

[0097] <Second variation of the implementation>

[0098] Figure 9 This is a cross-sectional view of a premixed combustion furnace in a second variation of an embodiment of the present invention.

[0099] In the first modification described above, the injection of low-reactive fuel F2 into the inner flow path 73 of the inner tube 65 via the second fuel injection flow path 74B was explained. However, the location of the second fuel injection flow path 74B is not limited to the location described in the first modification. Figure 9 As shown, for example, a second fuel injection path 74C for injecting low-reactive fuel F2 can be formed in the outer pipe 64, which is located upstream of the inner pipe 65 on the axis. This second fuel injection path 74C injects low-reactive fuel F2 into the internal space 69 of the outer pipe 64, which is located upstream of the inner pipe 65 on the axis. In this second variation, the second fuel injection path 74C injects low-reactive fuel F2 towards the central axis O and from the outer side of the radial direction of the inner pipe towards the inner side, so that most of the injected low-reactive fuel F2 flows into the inner flow path 73 of the inner pipe 65 and mixes with the compressed air Acom. That is, the thin-film air Af flowing into the thin-film air flow path 71 contains almost no low-reactive fuel F2.

[0100] Therefore, according to the second modified example of the premixed combustion furnace 61D, similarly to the first modified example, since a second fuel injection path 74C is formed on the upstream side of the axis of the first fuel injection path 74A, when using low-reactive fuel F2, it can be injected from the upstream side of the axis of the first fuel injection path 74A and mixed with compressed air Acom. Then, the distance from the second fuel injection path 74C to the outlet opening 68 can be lengthened, thereby suppressing flashback, promoting the mixing of compressed air Acom and low-reactive fuel F2, and reducing nitrogen oxides.

[0101] <Other Implementation Methods>

[0102] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments and may include design changes that do not depart from the spirit of the present invention.

[0103] For example, in the first, second, and first and second modifications of the above-described embodiments, a fuel injection flow path 74 is formed inside all the support pillars 66, but it is also possible to have support pillars 66 without a fuel injection flow path 74 formed therein. Furthermore, the number of support pillars 66 is not limited to the number in the above-described embodiments.

[0104] In the fuel injection device 60 described in the above embodiment, the case where the inner circumferential surface 64a of the outer tube 64 is formed into a circular cross-section and the inner tube 65 is formed into a cylindrical shape has been described. However, the shapes of the outer tube 64 and the inner tube 65 are not limited to the above shapes. For example, the inner circumferential surface 64a of the outer tube 64 can be formed into a polygonal cross-section, and the inner tube 65 can be formed into a cylindrical shape with a polygonal cross-section.

[0105] Furthermore, in the first embodiment and the first and second variations, a conical surface 72 is shown formed at the end 65d of Dod on the downstream side of the axis of the inner tube 65, but the conical surface 72 may be omitted.

[0106] Furthermore, in the structures of the first and second modifications described above, the outlet cross-section reduction portion 82 can also be provided as in the second embodiment. Additionally, while the first and second modifications show the use of two fuels with different combustion rates, it is also possible to provide three or more fuel injection paths with different combustion rates, spaced apart along the axial direction Do. In this case, the fuel with the lowest combustion rate should be injected more from the upstream side of the axis, Do.

[0107] Furthermore, in the above embodiments, the premixed combustion furnaces 61A to 61D used in the burner 40 of the gas turbine 10 have been described, but the premixed combustion furnace of the present invention can also be applied to burners other than gas turbines.

[0108] <Postscript>

[0109] Some or all of the above embodiments are described in the following notes, but are not limited thereto.

[0110] (1) According to the first embodiment, the premixed combustion furnace 61A to 61D includes: outer tubes 64 and 64B, each having an inlet opening 67 on a first side in the axial direction Do extending from axis O and an outlet opening 68 on a second side in the axial direction Do; inner tubes 65 and 65B, formed as cylindrical tubes extending along the axial direction Do, spaced apart from the inner sides of the outer tubes 64 and 64B, and forming a thin-film air flow path 71 between them for the flow of thin-film air Af; and a support column 66, extending inward from the inner wall surface 64a of the outer tubes 64 and 64B for support. The inner tubes 65 and 65B have their first-side ends positioned further to a second side than the inlet opening 67 of the outer tubes 64 and 64B, and their second-side ends positioned further to a first side than the outlet opening 68 of the outer tubes 64 and 64B. A fuel injection path 74 is formed in the outer tubes 64 and 64B, the support column 66, and the inner tubes 65 and 65B to inject fuel from the outside of the outer tubes 64 and 64B through the inside of the support column 66 to the inside of the inner tubes 65 and 65B.

[0111] According to the premixed combustion furnaces 61A to 61D of the first embodiment, a thin-film airflow path 71 is formed by arranging inner tubes 65 and 65B inside the outer tubes 64 and 64B. This allows the thin-film air Af to flow along the inner wall surface 64a of the outer tubes 64 and 64B on the second side, which is further in the axial direction Do than the inner tubes 65 and 65B. This suppresses the increase in fuel concentration in the flow contacting the inner wall surface 64a of the outer tubes 64 and 64B. Therefore, even when the flow velocity in contact with the inner wall surface 64a of the outer tubes 64 and 64B is lower than the combustion velocity, the upward flashback of the flame in the flow contacting the inner wall surface 64a of the outer tubes 64 and 64B can be suppressed.

[0112] Furthermore, in the premixed combustion furnaces 61A to 61D according to the first embodiment, since the end 65c of the first side Dou in the axial direction Do of the inner tubes 65 and 65B is positioned on the second side Dod, which is closer to the axial direction Do than the inlet opening 67 of the outer tubes 64 and 64B, the flow of compressed air Acom flowing in from the inlet opening 67 of the outer tubes 64 and 64B is not obstructed, and the compressed air Acom can be stably diverted to the thin-film air flow path 71 and the inner flow path 73. Moreover, since the end 65d of the second side Dod in the axial direction Do of the inner tubes 65 and 65B is positioned on the first side Dou, which is closer to the axial direction Do than the outlet opening 68 of the outer tubes 64 and 64B, the upward movement of the flame in contact with the inner wall surface 65b of the inner tubes 65 and 65B can be suppressed.

[0113] Furthermore, in the premixed combustion furnaces 61A to 61D according to the first embodiment, since the fuel injection flow path 74 is formed inside the outer pipe 64, outer pipe 64B, support column 66, and inner pipes 65 and 65B, the fuel F supplied to the fuel chamber 63 and the like outside the outer pipes 64 and 64B can be injected in a manner that crosses the inner wall surface 65b of the inner pipes 65 and 65B toward the internal flow path. Therefore, it is not necessary to form a dedicated piping for guiding the fuel injection flow path 74, and the fuel injection flow path 74 can be formed by effectively utilizing the interior of the support column 66 that supports the inner pipes 65 and 65B.

[0114] (2) According to the second method, in the premixed combustion furnace 61A to 61D involved in the first method, the outer tube 64 and the outer tube 64B can be configured such that, in the flow from the inlet opening 67 through the thin film air flow path 71 to the outlet opening 68, the fuel concentration of the flow that contacts the inner wall surface 64a of the outer tube 64 and the outer tube 64B is a fuel concentration below a reference concentration in the airflow where the flame cannot be maintained.

[0115] With this configuration, the fuel concentration in the flow that contacts the inner wall surface 64a of the outer tubes 64 and 64B is below the reference concentration, which can suppress the flame from reaching the flow that contacts the inner wall surface 64a of the outer tubes 64 and 64B. As a result, it is possible to suppress the occurrence of flame flashback that occurs during the flow that contacts the inner wall surface 64a of the outer tubes 64 and 64B.

[0116] (3) According to the third method, in the premixed combustion furnaces 61A to 61D involved in the second method, the inner tubes 65 and 65B may also be configured such that, in the flow flowing out from the end 65d of the second side Dod of the inner tubes 65 and 65B, the fuel concentration in contact with the inner wall surface 65b of the inner tubes 65 and 65B is below a reference concentration where the flame cannot be maintained in the airflow.

[0117] With this configuration, the fuel concentration in the flow contacting the inner wall surface 65b of the inner tubes 65 and 65B is below the reference concentration, which can suppress the flame from reaching the flow in contact with the inner wall surface 65b of the inner tubes 65 and 65B. As a result, it is possible to suppress the occurrence of flame flashback in the flow in contact with the inner wall surface 65b of the inner tubes 65 and 65B.

[0118] (4) According to the fourth method, the support 66 of the premixed combustion furnace 61A to 61D involved in any of the first to third methods is in the shape of a cross-section blade.

[0119] With this configuration, the flow resistance of the thin-film air Af flowing in the axial direction Do in the thin-film air flow path 71 can be reduced, thus suppressing the decrease in the flow velocity of the thin-film air Af.

[0120] (5) According to the fifth method, the premixed combustion furnace 61A, combustion furnace 61C, and combustion furnace 61D involved in any of the first to fourth methods have a conical surface 72 at the end 65d of the second side Dod of the inner tube 65, the conical surface 72 being inclined in such a way that the cross-sectional area of ​​the inner flow path 73 of the inner tube 65 increases as it moves toward the second side Dod.

[0121] By setting such a conical surface 72, for example, when it is necessary to set a conical surface 72 at the end 65d of the second side Dod in the axial direction Do due to the manufacturing of the inner tube 65, it is possible to suppress the expansion of the flow path cross-sectional area of ​​the thin film air flow path 71 and restore the static pressure of the thin film air Af, thereby reducing the flow velocity.

[0122] (6) According to the sixth method, the fuel F of the premixed combustion furnaces 61A to 61D of any of the first to fifth methods contains hydrogen.

[0123] Even when using highly reactive fuels containing hydrogen and with high combustion rates, flashback can be effectively suppressed.

[0124] (7) According to the seventh method, the outer tube 64B of the premixed combustion furnace 61B of any of the first to sixth methods has an outlet cross-section reduction portion 82 that gradually reduces the flow path cross-sectional area toward the outlet opening 68.

[0125] With this configuration, the flow path cross-sectional area of ​​the outer tube 64B can be reduced by the outlet cross-section reduction section 82, thereby suppressing the deceleration of the mainstream and thin-film air Af flowing out from the inner flow path 73 of the inner tube 65B. Furthermore, since the flow path cross-sectional area of ​​the inner flow path 73 is the same as that of the outlet end 83, the mainstream does not decelerate. Therefore, the development of vortices caused by the step formed at the end 65d of the second side Dod in the axial direction Do of the inner tube 65B can be suppressed.

[0126] (8) According to the eighth method, the premixed combustion furnace 61C of any of the first to seventh methods has a plurality of the pillars 66 (66A, 66B) spaced apart in the axial direction Do. In the outer tube 64, the plurality of pillars 66 spaced apart in the axial direction Do and the inner tube 65, a plurality of fuel injection flow paths 74 (74A, 74B) spaced apart in the axial direction Do are provided. The fuel injection flow path 74 that is located on the first side of the axial direction Do injects other fuels F2 with lower combustion speed.

[0127] (9) According to the ninth method, in any of the methods 1 to 7, in the premixed combustion furnace 61D, a second fuel injection path 74C is formed in the outer tube 64, which is located on the first side Dou of the axial direction Do, which is closer to the inner tube 65. The second fuel injection path 74C injects other fuel F2 with a combustion rate lower than that of the fuel F into the inner side of the outer tube 64.

[0128] According to the eighth and ninth methods, by forming a fuel injection flow path 74 on the first side Dou, which is further along the axial direction than the fuel injection flow path 74, when using other fuels F2 with low combustion speeds, it is possible to inject the other fuels F2 from the first side Dou and mix them with compressed air Acom. Therefore, the distance from the fuel injection flow path 74 that injects other fuels F2 to the outlet opening 68 can be increased, thereby suppressing flashback, promoting the mixing of compressed air Acom with other fuels F2, and reducing the amount of nitrogen oxides produced.

[0129] (10) According to the 10th method, the fuel injection device 60 includes: a plurality of the above-mentioned premixed combustion furnaces 61A to 61D; a housing 62 supporting the plurality of the premixed combustion furnaces 61A to 61D; and a fuel chamber 63 disposed inside the housing 62 and outside the outer tube 64.

[0130] Since the premixed combustion furnaces 61A to 61D described above can suppress flashback, damage to the fuel injection device 60 can be prevented.

[0131] (11) According to the 11th embodiment, the gas turbine 10 includes: a compressor 20 for generating compressed air; a combustor 40 having a fuel injection device 60 as described in the 10th embodiment and a combustion chamber 50 for generating combustion gas G by burning a mixture Gm injected from the fuel injection device 60; and a turbine 30 driven by the combustion gas G generated in the combustor 40.

[0132] By equipping the gas turbine 10 with the fuel injection device 60 as described above, the reliability of the gas turbine 10 can be improved.

[0133] Industrial availability

[0134] The above method can suppress the occurrence of flashbacks.

[0135] Symbol Explanation

[0136] 10-Gas turbine, 11-Gas turbine rotor, 15-Gas turbine casing, 16-Intermediate casing, 20-Compressor, 21-Compressor rotor, 22-Rotor shaft, 23-Rotating blade row, 25-Compressor casing, 26-Fixed blade row, 30-Turbine, 31-Turbine rotor, 32-Rotor shaft, 33-Rotating blade row, 35-Turbine casing, 36-Fixed blade row, 40-Burner, 50-Combustion chamber, 60-Fuel injection device, 61A, 61B, 61C, 61D-Premixed combustion furnace, 62-Casing, 63-Fuel chamber, 63A-First fuel chamber, 63B-Second fuel chamber, 64, 64B - Outer tube, 64a- Inner circumferential surface, 65, 65B- Inner tube, 65a- Outer circumferential surface, 65b- Inner circumferential surface, 65c- End, 65d- End, 66- Support, 66A- First support, 66B- Second support, 66a- First surface, 66b- Second surface, 67- Inlet opening, 68- Outlet opening, 69- Internal space, 71- Thin film airflow path, 72- Conical surface, 73- Inner flow path, 74- Fuel injection flow path, 74A- First fuel injection flow path, 74B, 74C- Second fuel injection flow path, 81- Outer tube body, 82- Outlet cross-section reduction section, 83- Outlet end, 84- Internal space, 85- Chamfered section.

Claims

1. A premixed combustion furnace, comprising: The outer tube has an inlet opening on a first side in the axial direction of the axis extending from the axis and an outlet opening on a second side in the axial direction; The inner tube, formed as a cylinder extending along the axial direction, is spaced apart from the inner side of the outer tube and forms a thin-film airflow path between it and the outer tube for thin-film airflow; and A support column extends inward from the inner wall of the outer tube to support the inner tube. The end of the inner tube on the first side is positioned further to the second side than the inlet opening of the outer tube. The end of the inner tube on the second side is positioned further to the first side than the outlet opening of the outer tube. A fuel injection path is formed in the outer tube, the support column, and the inner tube, through which fuel is injected from the outside of the outer tube, through the inside of the support column, and into the inside of the inner tube.

2. The premixed combustion furnace according to claim 1, wherein, The outer tube is formed such that, in the flow from the inlet opening through the thin-film airflow path to the outlet opening, the length of the flow in contact with the inner wall surface of the outer tube is a fuel concentration below a reference concentration at which a flame cannot be maintained in the airflow.

3. The premixed combustion furnace according to claim 2, wherein, The inner tube is formed such that, in the flow exiting from the end of the second side of the inner tube, the fuel concentration of the flow in contact with the inner wall surface of the inner tube is below a reference concentration at which the flame cannot be maintained in the airflow.

4. The premixed combustion furnace according to any one of claims 1 to 3, wherein, The support column is in the shape of a blade cross section.

5. The premixed combustion furnace according to any one of claims 1 to 3, wherein, The end of the inner tube on the second side has a tapered surface that is inclined in such a way that the flow path cross-sectional area of ​​the inner tube increases as it moves toward the second side.

6. The premixed combustion furnace according to any one of claims 1 to 3, wherein, The fuel contains hydrogen.

7. The premixed combustion furnace according to any one of claims 1 to 3, wherein, The outer tube has an outlet cross-section reduction section, which causes the flow path cross-sectional area to gradually decrease towards the outlet opening.

8. The premixed combustion furnace according to any one of claims 1 to 3, comprising: Multiple pillars are formed at intervals along the axial direction. In the outer tube, the plurality of support pillars spaced apart in the axial direction, and the inner tube, a plurality of fuel injection flow paths are provided, spaced apart in the axial direction. The more the fuel injection path is positioned on the first side of the axial direction, the more it injects other fuels with lower combustion rates.

9. The premixed combustion furnace according to any one of claims 1 to 3, wherein, In the outer tube, which is located on a first side closer to the axial direction than the inner tube, a second fuel injection path is formed to inject other fuels with a lower combustion rate than the fuel into the inner side of the outer tube.

10. A fuel injection device comprising: The premixed combustion furnace according to any one of claims 1 to 9; The shell supports the plurality of the premixed combustion furnaces; and The fuel chamber is located inside the housing and outside the outer tube.

11. A gas turbine comprising: The compressor generates compressed air; A burner comprising the fuel injection device as claimed in claim 10 and a combustion chamber for generating combustion gases by burning a mixture injected from the fuel injection device; and The turbine is driven by the combustion gases generated in the burner.

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