Combustor and combustion nozzle suitable for hydrogen gas turbines

Abstract

To provide a combustion nozzle 2 which has a structure appropriate to a combustor 1 for a small-class gas turbine capable of utilizing hydrogen as fuel, to sufficiently and uniformly mix air and hydrogen before combustion in a small space while avoiding back fire and attain combustion in the state that the fuel is lean, and the combustor 1 including the same.SOLUTION: In a combustor 1 for a gas turbine, a combustion nozzle 2 jets compressed air PA and fuel F to be combusted, into a combustion chamber 3. The combustion nozzle includes an air flow path 2x which is defined to receive the compressed air from an air inflow port 4a and discharge the compressed air from a nozzle port 2d opened to a combustion chamber interior 3f, and a fuel flow path 2 φ which is defined to receive the fuel and discharge the fuel from a fuel outflow hole 2f into the flow of the compressed air jetted from the nozzle port. In the air flow path between the air inflow port and the nozzle port, there is provided a restriction section 2e with a flow path cross section area for the compressed air being relatively smaller. In the restriction section, the fuel outflow hole is provided.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a combustor of a gas turbine engine (hereinafter referred to as a "gas turbine"), a nozzle (combustion nozzle) for injecting compressed air and fuel into a combustion chamber of the combustor and burning them, and a combustor, and more particularly, to a combustor suitable for a gas turbine (hydrogen gas turbine) that can use hydrogen as fuel and its combustion nozzle.

Background Art

[0002] From the perspective of preventing global warming and decarbonization, research and development of heat engines such as gas turbines that use hydrogen as fuel are progressing. For example, Patent Document 1 proposes a combustor for a gas turbine that uses hydrogen and methane as fuel, in which methane, the main fuel, is injected from a premixed combustion type main burner located upstream of the combustion cylinder that forms the combustion chamber to form a combustion field, and multiple diffusion combustion type re-burners are provided in that combustion field, injecting fuel from the peripheral wall into the combustion chamber, and hydrogen is introduced from some of them. With this configuration, because the main burner is a premixed combustion type, the amount of NOx in the high-temperature combustion gas generated in the primary combustion region upstream of the combustion chamber is suppressed, and the amount of hydrogen introduced is also reduced by distributing the re-burners, which dilutes the fuel concentration in the combustion region of each re-burner, keeping the combustion temperature of each re-burner low overall and suppressing the generation of NOx. Furthermore, in this configuration, the risk of flashback is low because diffusion combustion type re-burners are used. Patent Document 2 proposes a combustor structure for a gas turbine that uses a highly reactive gas such as hydrogen as fuel, which achieves low NOx combustion and flashback prevention and suppresses combustion vibration. This structure includes a plurality of annular fuel injection units arranged concentrically on the upstream end face of a combustion cylinder that forms a combustion chamber, and each fuel injection unit has an annular fuel injection member having a plurality of fuel injection holes opening on its outer and / or inner circumferential surface, and an annular air guide member that guides air to the fuel gas injected from each fuel injection hole of the annular fuel injection member. The structure also includes a plurality of radially extending circumferential isolation walls that isolate the gas passages of the annular fuel injection units at equal intervals in the circumferential direction, and at least one of the radially extending isolation walls that isolates two adjacent annular fuel injection units in the radial direction. Furthermore, Patent Document 3 proposes a configuration for a gas turbine system in which fuel-air is supplied to the combustion chamber as multiple coaxial jets in order to reduce NOx emissions and promote the mixing of fuel and air to improve the stability of the flame in the combustion chamber. This configuration forms an airflow around the outer periphery of the fuel flow within the premixed flow path.In this configuration, premixing allows for leaner combustion and advantageously reduces NOx emissions. However, creating a good mixture requires a large space, which in turn increases the risk of flashback. Therefore, by using multiple nozzles, combustion can occur in a narrow space for a short time, thus suppressing flashback. Although the configuration described in the document is not limited to hydrogen as the fuel, it forms the basic configuration for subsequent hydrogen combustion-related structures. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-109309 [Patent Document 2] Japanese Patent Publication No. 2020-106258 [Patent Document 3] Japanese Patent Publication No. 2003-148734 [Overview of the project] [Problems that the invention aims to solve]

[0004] Hydrogen gas turbines, which use hydrogen as fuel and do not emit CO2, are expected to become more widespread. To achieve this, it would be advantageous to miniaturize the gas turbine so that it can be installed in vehicles such as automobiles.

[0005] Incidentally, when using hydrogen as fuel for a gas turbine, since hydrogen has a higher combustion temperature than hydrocarbon-based fuels that have been commonly used until now, in order to suppress the generation of NOx, it is required (more strongly than with conventional hydrocarbon-based fuels) to thoroughly and uniformly mix the fuel and air before combustion, and to keep the overall fuel concentration lean to keep the combustion temperature low, so as not to create areas where the fuel concentration is locally high and the combustion temperature is high. Furthermore, since hydrogen burns faster than hydrocarbon-based fuels and its flame extinction distance (0.64 mm) is shorter than that of hydrocarbon-based fuels (about 2 mm), a different configuration is required in the part where the fuel is injected into the combustion chamber compared to when conventional hydrocarbon-based fuels are used, in order to suppress the occurrence of flashback, where combustion flows back into the fuel passage.

[0006] In this regard, conventionally known configurations of gas turbine combustors that can use hydrogen as fuel are intended for medium to large-scale power generation engines with a power output exceeding 1 MW, and are annular combustors. It is difficult to apply them to small engines with a power output of 1 MW or to annular combustors. For example, in the case of micromix combustors (e.g., Patent Document 2) and multi-cluster combustors, which are known as conventional configurations of gas turbine combustors that can use hydrogen as fuel, hydrogen is sprayed at multiple locations and the flame is distributed to be as small as possible to suppress localized high fuel concentrations, and the fuel in the combustion field is kept lean to suppress the rise in combustion temperature and suppress the generation of NOx. In this case, the structure is complex, the number of parts is large, and a large space is required, making it difficult to miniaturize the combustor. Furthermore, if the hydrogen supply port to the combustion chamber is made smaller to avoid flashback of hydrogen, which has a short flame extinction distance, then, as seen in conventional structures (Patent Document 2, etc.), in configurations where air and hydrogen are mixed near the hydrogen supply port, it becomes difficult to sufficiently and uniformly mix air and hydrogen before combustion in a small space, requiring a larger space. Therefore, in order to appropriately avoid flashback and suppress NOx generation in a small class gas turbine that can use hydrogen as fuel, it is advantageous to have a novel combustion nozzle structure that can sufficiently and uniformly mix air and hydrogen before combustion in a small space and that can achieve combustion in a lean fuel state.

[0007] Thus, the main objective of the present invention is to provide a novel combustion nozzle structure suitable for the combustor of a small-scale gas turbine that can utilize hydrogen as fuel.

[0008] Furthermore, one of the objectives of the present invention is to provide a combustion nozzle that can be used in the combustor of a small class gas turbine as described above, and which has a novel structure that can sufficiently and uniformly mix air and hydrogen before combustion while avoiding flashback in a small space, and can achieve combustion in a lean fuel state.

[0009] Furthermore, another objective of the present invention is to provide a combustor for a gas turbine equipped with the combustion nozzle described above. [Means for solving the problem]

[0010] According to the present invention, the above problem is solved by a combustion nozzle that injects compressed air and fuel to be burned into the combustion chamber of a gas turbine combustor, An air passage defined to receive the compressed air from an air inlet and discharge the compressed air from a nozzle opening that opens into the combustion chamber, A fuel passage is defined to receive the fuel and to flow out from the fuel outlet hole to the compressed air flow that ejects the fuel from the nozzle opening. It has, This is achieved by a combustion nozzle in which a throttling section is provided in the air passage that connects the air inlet and the nozzle opening, in which the cross-sectional area of ​​the compressed air passage is relatively small, and the fuel outlet is provided in the throttling section.

[0011] In the above configuration, the "combustion nozzle" is, as described above, a nozzle that mixes compressed air and fuel to be burned and injects it into the combustion chamber of the gas turbine combustor. The "air passage" is the passage through which air flows, defined between the "air inlet" that receives compressed air and the "nozzle opening" that opens into the combustion chamber, and the "fuel passage" is the passage that receives fuel and allows it to flow to the "fuel outlet". The "throttling section" is a section in the air passage connecting the air inlet and the nozzle opening where the "cross-sectional area of ​​the passage" (the cross-sectional area of ​​the area through which the fluid can flow) is relatively smaller than the sections before and after that section. The fuel outlet, which is the exit of the fuel passage, is opened in the throttling section of the air passage and is provided to inject fuel into the flow of compressed air flowing through it. The fuel may be hydrogen.

[0012] According to the combustion nozzle configuration of the present invention described above, as compressed air enters the airflow path from the air inlet and exits the nozzle opening, the flow velocity of the compressed air increases as it passes through a restricted section where the flow path cross-sectional area is reduced. At that point, fuel is released into the compressed air flow, and as a result, the fuel is dispersed within the compressed air flow at a higher flow velocity. This allows the fuel to be mixed more uniformly and sufficiently with the compressed air than when the fuel is simply added to the compressed air flow, suppressing the occurrence of regions with locally high fuel concentrations. Furthermore, when the compressed air flow with dispersed fuel flows out of the nozzle opening into the combustion chamber after passing through the restricted section, the space expands, reducing the overall fuel concentration. In addition, since the fuel is released when the compressed air flow velocity is high, flashback into the fuel flow path can be avoided even when the fuel is hydrogen, which has a high combustion rate. Accordingly, according to the above configuration of the present invention, in the relatively short distance the compressed air passes through the nozzle, that is, in a relatively small space, the compressed air and fuel are sufficiently mixed while avoiding flashback, and a lean fuel state can be achieved in the combustion field. As a result, the combustion temperature does not become excessively high, and the amount of NOx generated can be suppressed. The extent to which the flow path cross-sectional area in the restricted section is narrowed relative to the flow path cross-sectional area before and after that section may be determined by suitability. In particular, when the fuel is hydrogen, its density is much lower than that of hydrocarbon fuels, and the inertial force when ejected from the fuel outlet is small (weak force). Therefore, in the above configuration, it is preferable that a plurality of fuel outlets are arranged substantially evenly along the circumferential direction of the air flow path so that the fuel is more reliably dispersed uniformly in the compressed air flow. The number of fuel outlets may be determined by suitability. Furthermore, in order to more reliably avoid flashback from the combustion chamber to the fuel outlet, the inner diameter (hole diameter) of the fuel outlet may be configured to be smaller than the flame extinction distance of the fuel. Specifically, when the fuel is hydrogen, the flame extinction distance is approximately 0.64 mm, so the diameter of the fuel outlet can be, for example, 0.6 mm or less.

[0013] In the above configuration, more specifically, in the restricted section of the airflow path, a first region may be defined along the direction of compressed air flow, where the flow path cross-sectional area gradually decreases from the upstream side of the restricted section, and a second region where the flow path cross-sectional area gradually increases from the downstream end of the first region toward the nozzle opening. With such a configuration, the flow path cross-sectional area of ​​the compressed air flow is smoothly and continuously restricted and then smoothly expanded, so that the compressed air flow flows through the airflow path with a smooth change in flow velocity and with almost no stagnation, and it is expected that there will be almost no regions with locally high fuel concentration, the fuel will be more uniformly distributed, and the combustion temperature will be more uniformly distributed in the combustion field. In this configuration, the fuel passage extends through the circumferential wall defining the air passage, and the fuel outlet may be opened on the inner surface of the circumferential wall in a second region where the cross-sectional area of ​​the passage in the restricted section gradually increases, or it may be opened on the inner surface of the circumferential wall near the downstream end of the first region of the restricted section (the upstream end of the second region), that is, at the point in the restricted section where the cross-sectional area of ​​the passage is smallest or near thereto. With this configuration, it is expected that fuel will be injected where the flow velocity of the compressed air flow is high, and the fuel will be dispersed more uniformly. The specific location of the fuel outlet may be determined by suitability.

[0014] In the above configuration, a swirler that converts the compressed air flow into a swirling flow in any manner may be provided upstream of the throttling section of the airflow path in order to more uniformly distribute the fuel in the compressed air flow. As the compressed air flow passes through the throttling section as a swirling flow and fuel is released there, the fuel is better dispersed in the airflow over the short distance the airflow travels. For example, such a swirler may have a center cone positioned along the central axis of the airflow path that is in line with the direction of the compressed air flow, and a wing-shaped member extending radially from the center cone, the surface of which is inclined with respect to the central axis of the airflow path, and the compressed air flow may be configured to become a swirling flow as it flows along the surface of the wing-shaped member (it may be in the shape of a non-rotating screw). In a swirler with such a configuration, if the outer diameter of the center cone through which air does not flow is too large relative to the inner diameter of the air passage, the flow velocity along the extension of the center cone will decrease, increasing the likelihood of flames flowing back from the combustion field to the center cone. Therefore, the ratio of the outer diameter of the swirler's center cone to the inner diameter of the swirler's installation location in the air passage may be configured to be below a predetermined value adjusted so that the flow velocity along the extension of the center cone does not become too low. Alternatively, it is preferable that the ratio of the outer diameter of the swirler's center cone to the inner diameter of the swirler's installation location in the air passage is configured to be large enough to prevent backflow of fluid from the combustion chamber into the air passage, thereby preventing melting of the tip of the center cone by flames.

[0015] Furthermore, to more reliably prevent melting of the tip of the center cone of the swirler due to flames, a configuration may be adopted in which a flow channel is formed inside the center cone of the swirler that penetrates the center cone along the central axis aligned with the direction of compressed air flow in the air passage, and has a fluid outlet hole opened at the downstream tip of the center cone. Compressed air flows through the flow channel inside the center cone and is ejected from the fluid outlet hole toward the combustion chamber. With such a configuration, airflow is also ejected from the tip of the center cone, preventing flames from reaching the tip of the center cone, and thus more reliably preventing melting of the tip of the center cone.

[0016] In the above swirler configuration, the center cone may extend such that its downstream end is located in a first region where the cross-sectional area of ​​the throttled section of the airflow path gradually decreases, or it may extend to a second region where the cross-sectional area of ​​the throttled section of the airflow path gradually increases. In the former case, the tip of the center cone is positioned at a distance from the combustion field, preventing melting of the tip of the center cone. In the latter case, the flow velocity of the airflow around the tip of the center cone increases, preventing backflow of the combustion fluid to the tip of the center cone.

[0017] In yet another embodiment, a central cone channel may be formed that penetrates the center cone of the swirler along the central axis in line with the direction of compressed air flow in the air passage, and has a fluid outlet hole opened at the downstream end of the center cone where the compressed air flow is located. Fuel is circulated within the central cone channel, and compressed air is ejected from the fluid outlet hole toward the combustion chamber. With such a configuration, it is expected that the fuel will be better mixed with the compressed air flow near the nozzle opening.

[0018] Alternatively, a further air passage (peripheral air passage) may extend through the peripheral wall defining the air passage, and the compressed air flow that has passed through it may be discharged into the compressed air flow that has passed through the air passage from an air outlet hole provided on the inner surface of the peripheral wall in the second region of the throttling section or on the inner surface of the peripheral wall near the downstream end of the first region of the throttling section. With such a configuration, it is expected that the air and fuel will be better mixed in the mixed gas of compressed air and fuel sent to the combustion chamber, the formation of combustion concentration unevenness will be suppressed, and the amount of NOx generated will be further suppressed. The direction of fluid ejection at the air outlet hole and fuel discharge hole may be inclined in any direction with respect to the radial direction from the central axis of the air passage. This is expected to further improve the mixing of air and fuel.

[0019] In the combustor of a gas turbine equipped with a combustion nozzle as described above, in the combustion chamber, compressed air and fuel are sufficiently mixed, and a state where the fuel is dilute can be realized in the combustion field. Thus, as described above, the combustion temperature does not become excessively high, and the generation amount of NOx can be suppressed. Thus, according to the present invention, there is provided a combustor of a gas turbine, which is a combustion nozzle for ejecting compressed air and fuel to be burned into the combustion chamber, an air flow path defined to receive the compressed air from an air inlet and discharge the compressed air from a nozzle opening that opens into the combustion chamber, a fuel flow path defined to receive the fuel and discharge the fuel into a flow of the compressed air ejected from a fuel outlet hole from the nozzle opening and having a combustion nozzle provided with a throttle section where the flow path cross-sectional area of the compressed air is relatively small in the air flow path communicating between the air inlet and the nozzle opening, and the fuel outlet hole is provided in the throttle section is provided. In the combustor of the present invention, the combustion nozzle may have the various characteristic configurations described above, and such cases also belong to the scope of the present invention. is provided.

Effect of the Invention

[0020] Thus, the combustion nozzle of the combustor of the gas turbine of the present invention described above can achieve sufficiently more uniform mixing of fuel with the compressed air flow and dilution of the fuel concentration at a relatively short distance when discharging the compressed air flow and the fuel into the combustion chamber. Therefore, even when using a fuel with a high combustion temperature such as hydrogen, it can be used as a combustion nozzle for a small-class gas turbine combustor with the generation amount of NOx suppressed while avoiding backfire. The combustion nozzle of the present invention and the combustor equipped with the same can be used in a gas turbine using hydrogen as fuel, which is miniaturized so as to be mounted on vehicles such as automobiles. Thereby, a wider spread of hydrogen gas turbines is expected.

[0021] Other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1(A) is a schematic cross-sectional view of a combustor of a gas turbine to which a combustion nozzle according to the present embodiment is applied. FIG. 1(B) is a schematic perspective view of the combustion nozzle according to the present embodiment, and FIG. 1(C) is a schematic cross-sectional view of the combustion nozzle according to the present embodiment (viewed from line 1C-1C in FIG. 1(B)). FIG. 1(D) is a schematic perspective view of a swirler disposed in the air flow path of the combustion nozzle of the present embodiment. [Figure 2] FIG. 2 is a schematic enlarged cross-sectional view of the vicinity of the nozzle opening and the throttle section of the combustion nozzle according to the present embodiment. [Figure 3] FIGS. 3(A) and (B) are schematic cross-sectional views of the combustion nozzle according to the present embodiment, showing simulation results of the velocity distribution of the fluid ejected from the nozzle opening. In the figure, the speed of the flow velocity is represented by the shade of brightness. (A) is the case where the boss ratio (R1 / R2) is 0.4, and (B) is the case where the boss ratio exceeds 0.4. [Figure 4] FIGS. 4(A) to (E) are schematic cross-sectional views of various modified examples of the combustion nozzle according to the present embodiment. (A) is an example in which the fuel outflow holes are provided in a region where the flow path cross-sectional area of the throttle section gradually increases toward the nozzle opening. (B) is an example in which the fuel outflow holes are provided in the vicinity of the position where the flow path cross-sectional area of the throttle section is minimum and on the upstream side. (C) is an example in which a region where the flow path cross-sectional area is minimum in the throttle section is formed to have a certain length in the fluid flow direction. (D) is an example in which the nozzle opening is provided without the flow path cross-sectional area gradually increasing from the position where the flow path cross-sectional area of the throttle section is minimum. (E) is an example in which the center cone of the swirler disposed in the air flow path protrudes to the position where the flow path cross-sectional area of the throttle section is minimum. [Figure 5]Figures 5(A) to (C) are schematic cross-sectional views of various modifications of the combustion nozzle according to this embodiment. (A) is an example in which the center cone of the swirler placed in the air passage protrudes to a position where the cross-sectional area of ​​the passage in the throttled section is minimized, and the fuel passage penetrates through the inside of the center cone along with the peripheral wall of the nozzle, so that fuel is injected from the tip of the center cone as well. (B) is an example in which the center cone of the swirler placed in the air passage protrudes to a position where the cross-sectional area of ​​the passage in the throttled section is minimized, and the fuel passage penetrates through the inside of the center cone, so that fuel is injected from the tip of the center cone. (C) is an example in which the center cone of the swirler placed in the air passage protrudes to a position where the cross-sectional area of ​​the passage in the throttled section is minimized, the fuel passage penetrates through the inside of the center cone, and the fuel outlet is formed to inject fuel circumferentially near the tip of the center cone. [Figure 6] Figure 6 is a schematic cross-sectional view of a further modification of the combustion nozzle according to this embodiment, in which a swirler, which is placed in the air passage, is provided at an air inlet drilled in the nozzle periphery. [Figure 7] Figure 7(A) is a schematic cross-sectional view of a further modification of the combustion nozzle according to this embodiment, in which the air passage is formed to penetrate the inside of the center cone of the swirler, and air is ejected from the tip of the center cone. Figures 7(B) and (C) are schematic cross-sectional views of the combustion nozzle according to this embodiment, showing the simulation results of the temperature distribution of the fluid around the nozzle opening. The temperature level is represented by the intensity of the brightness. (B) is the case where air is ejected from the tip of the center cone, and (C) is the case where air is not ejected from the tip of the center cone. [Figure 8]Figure 8(A) is a schematic cross-sectional view of a further modification of the combustion nozzle according to this embodiment, in which an air passage is formed to penetrate the interior of the nozzle circumferential wall, and in the throttling section, not only fuel but also air is ejected from the circumferential wall. Figures 8(B) and (C) are cross-sectional views of the air passage in the throttling section near the nozzle opening, viewed from a direction perpendicular to the flow direction, and show the arrangement of the fuel outlet and air outlet. In (B), the fuel outlet and air outlet are arranged alternately along the circumferential direction of the nozzle opening and extend approximately radially from the center of the nozzle opening, and in (C), the fuel outlet and air outlet are arranged alternately along the circumferential direction of the nozzle opening and extend inclined radially from the center of the nozzle opening. [Figure 9] Figure 9(A) is a schematic cross-sectional view of a further modification of the combustion nozzle according to this embodiment, which is an example in which air is ejected from the outer circumference of the nozzle opening. Figure 9(B) is a schematic front view (viewed from a direction perpendicular to the fluid flow from the nozzle opening) of an annular member in which ejection holes for ejecting air from the outer circumference of the nozzle opening are arranged. [Explanation of Symbols]

[0023] 1… Combustor 2… Combustion nozzle 2a…Fuel supply pipe 2b... Nozzle peripheral wall 2d... Nozzle opening 2e…Aperture section 2ei…Gradual decrease region in the aperture range 2eii… Gradual increase region of aperture interval 2et…Minimum diameter region of the aperture section 2f…Fuel outflow hole 2x…Airflow channels 2φ…Fuel passage 2g…Air outlet 3… Combustion chamber 3F... Combustion area 3h... Combustion chamber housing (peripheral wall) 3o…Combustion chamber opening 4…Compressed air supply ring 4a...Air inlet 4b...Air passage within the peripheral wall 5... Swallow 5c... Swirler Center Cone 5w... Swirl wing-shaped member 6... Ring for air ejection 6a...Air vent F…Fuel flow PA...Compressed air flow [Best Mode for Carrying Out the Invention]

[0024] Basic configuration of a combustor and combustion nozzle The combustion nozzle of this embodiment is advantageous for use in the combustor of a gas turbine that uses hydrogen or other hydrocarbon-based substances that are lighter in mass and have a higher combustion temperature than those conventionally used. As shown in Figure 1(A), in the combustor 1 of a gas turbine, the combustion nozzle 2 is installed in the opening 3o of the housing 3h of the combustion chamber 3 that defines the combustion field 3f. In short, in the combustion nozzle 2, compressed air PA flows in from a compressor (not shown) connected to the turbine (not shown) through an annular compressed air supply ring 4 defined on the outer circumference of the combustion chamber 3, and fuel F flows in from a fuel tank (not shown) through a fuel supply pipe 2a, and these are mixed and released into the combustion field 3f for combustion.

[0025] In the basic configuration of the combustion nozzle 2, as shown in Figures 1(B) and (C), a substantially cylindrical peripheral wall portion 2b extends in the axial direction of its central portion, defining an air passage 2x that opens at a nozzle opening 2d that fits into the opening 3o of the combustion chamber. Compressed air PA is taken in from an air inlet 4a formed on the upstream side of the peripheral wall portion 2b and discharged from the nozzle opening 2d into the combustion field 3f (the cross-section of the air passage 2x perpendicular to the fluid flow direction may be substantially circular, but is not limited to this). Furthermore, a fuel passage 2φ is formed to pass through the interior of the peripheral wall portion 2b, through which fuel F supplied via the fuel supply pipe 2a flows. This passage opens at a fuel outlet hole 2f in the inner wall of the peripheral wall portion 2b, and fuel is injected towards the compressed air flow PA flowing through the air passage 2x. Typically, the fuel outlet holes 2f are arranged at substantially equal intervals at multiple locations along the circumferential direction of the air passage 2x. Furthermore, within the peripheral wall portion 2b, the fuel passage 2φ is formed to penetrate the portion of the air passage that is not inserted into, so as not to interfere with the air passage from the air inlet 4a to the air passage 2x. In addition, a swirler 5, which has the shape of a non-rotating screw, is arranged inside the air passage 2x defined by the peripheral wall portion 2b, as schematically depicted in Figure 1(D), and has a center cone 5c extending along approximately the center of the air passage 2x and a plurality of wing-shaped members 5w extending radially around the center cone 5c. In such a swirler 5, the surfaces of the plurality of wing-shaped members 5w are inclined with respect to the central axis of the air passage, so that the flow direction rotates as the compressed air flow flows along the surface of the wing-shaped members 5w, and a swirling flow is formed.

[0026] In particular, in the combustion nozzle 2 of this embodiment, as shown in Figure 1(C), a "throttling section" 2e is formed in the air passage 2x, that is, a section in which the flow path cross-sectional area (the cross-sectional area in the direction perpendicular to the direction of fluid flow in the area through which the fluid can flow) is narrowed to be relatively smaller than the sections before and after it, and the fuel outlet hole 2f is located in this throttling section 2e. With this configuration, to put it simply, as explained in the "Summary of the Invention" section, when the compressed air PA passes through the throttling section 2e, its flow velocity increases, and at that point the fuel F is released into the compressed air flow PA. As a result, the fuel F is dispersed within the compressed air flow PA at a higher flow velocity, so that the fuel is mixed more uniformly and sufficiently with the compressed air over a shorter travel distance than when the fuel is simply added to the compressed air flow, and the occurrence of areas with locally high fuel concentrations is suppressed. Then, after the compressed air flow PA, in which the fuel F is dispersed, passes through the restricted section 2e, it flows out from the nozzle opening 2e into the combustion field 3f in the combustion chamber, where it spreads out in a wide space, reducing the overall fuel concentration. Furthermore, since the fuel outlet 2f is provided where the flow velocity of the compressed air PA increases, the fuel F is released, so even when the fuel is hydrogen, which has a short flame extinction distance, flashback into the fuel flow path 2φ can be avoided. Thus, according to the configuration of this embodiment, while avoiding flashback, the fuel is more uniformly diluted and dispersed in relation to the air at the nozzle opening 2d, thereby making it possible to suppress the amount of NOx generated.

[0027] In the air passage 2x of this embodiment described above, the ratio of the flow path cross-sectional area or inner diameter of the throttling section 2e to the regions before and after the throttling section 2e, and the length of the throttling section 2e in the flow direction, may be determined by adaptation so that the fuel is more uniformly distributed in the compressed air PA flow. Referring to Figure 2, the flow path cross-sectional area (πX) of the portion of the throttling section 2e where the flow path cross-sectional area is smallest (minimum diameter X) is shown. 2 / 4) is the flow path cross-sectional area (π(4YYr-Yr) upstream of the diaphragm section 2e). 2The dimensions of the throttling section 2e may be set so as to be significantly smaller than ) / 4). Typically, the ratio of the minimum diameter X of the throttling section 2e to the inner diameter Y on the upstream side of the throttling section 2e may be 40-80%. Furthermore, as shown in the figure, the throttling section 2e may be configured such that, along the direction of fluid flow, the inner diameter and flow path cross-sectional area gradually decrease from the upstream side of the throttling section 2e (first region 2ei), and after reaching the minimum diameter portion, the inner diameter and flow path cross-sectional area gradually increase toward the nozzle opening 2d (second region 2eii), thereby allowing the flow velocity of the compressed air flow to increase and decrease smoothly without stagnation.

[0028] The fuel outlet 2f provided in the throttling section 2e may be located where the flow velocity of the compressed air is high, and its position may be determined by suitability so that the fuel is more uniformly dispersed in the flow of compressed air PA. Preferably, the fuel outlet 2f is located near the smallest diameter portion of the throttling section 2e. Specifically, the vicinity of the smallest diameter portion of the throttling section 2e is the section pt before and after the smallest diameter portion in Figure 2, and the length pt of this vicinity section may be a section where pt / p ≤ 60% of the length p of the throttling section 2e (length of the section where the inner diameter is smaller than Y) is satisfied.

[0029] The diameter of the fuel outlet 2f should preferably be set smaller than the fuel extinction distance to prevent flashback, where the burned fluid flows back into the fuel passage. If the fuel is hydrogen, the hydrogen extinction distance is 0.64 mm, so the diameter of the fuel outlet may be less than that, for example, 0.6 mm or less.

[0030] Furthermore, if the fuel is a light substance such as hydrogen, the inertial force (momentum) is small when ejected from the fuel outlet, and if the fuel is ejected only from one edge of the airflow, it will take time to disperse throughout. Therefore, the fuel outlet may be provided at multiple locations approximately evenly along the circumferential direction of the compressed airflow, as shown in the figure, so that the fuel is more uniformly dispersed within the airflow.

[0031] Furthermore, as described above, when a swirler 5 that rotates the direction of airflow is provided in the air passage 2x, the compressed air flow becomes a swirling flow as it passes through the throttling section 2e, so that the fuel is more evenly dispersed in the compressed air flow. In such a swirler 5, as described above, a center cone 5c extends approximately to the center of the air passage 2x. In this regard, research by the inventors of this embodiment has shown that if the ratio of the cross-sectional area or diameter R1 of the center cone 5c to the cross-sectional area or inner diameter R2 of the air passage 2x is too large, the fluid velocity on the extension of the center cone 5c at the nozzle opening 2d is relatively reduced compared to the fluid velocity around it, and heat from the combustion field 3f can more easily reach the tip of the center cone 5c. As shown in Figures 3(A) and (B), according to the inventor's simulation of this embodiment, when the ratio R1 / R2 (referred to as the "boss ratio") between the outer diameter R1 of the center cone 5c and the inner diameter R2 (= Y in Figure 2) of the air passage 2x upstream of the constricted section 2e is less than 0.4, as shown in Figure 3(A), there is almost no region where the flow velocity is reduced along the extension of the center cone 5c at the nozzle opening 2d. On the other hand, when the boss ratio R1 / R2 exceeds 0.4, as shown in Figure 3(B), a region where the flow velocity is reduced along the extension of the center cone 5c at the nozzle opening 2d appears, and it was observed that backflow rf of the combustion fluid from the combustion field 3f to the center cone 5c is more likely to occur. Therefore, in the combustion nozzle of this embodiment, the outer diameter of the center cone of the swirler may preferably be designed so that the boss ratio R1 / R2 is not excessive (for example, so that it is 0.4 or less (cross-sectional area ratio is 0.16 or less)).

[0032] Example of combustion nozzle configuration The specific configuration of this embodiment can be modified in various ways while satisfying the above preferred requirements. For example, the fuel outlet 2f may be opened at the approximately minimum diameter portion of the throttling section 2e, as shown in Figure 1(C). Alternatively, if the flow velocity of the compressed air flow is relatively high, it may be opened in a region 2eii where the flow path cross-sectional area from the minimum diameter portion of the throttling section 2e to the nozzle opening 2d gradually increases, as shown in Figure 4(A). Or, as shown in Figure 4(B), it may be opened in a region 2ei where the flow path cross-sectional area near the minimum diameter portion of the throttling section 2e gradually decreases. Furthermore, as shown in Figure 4(C), the region 2ct where the flow path cross-sectional area of ​​the throttling section 2e is minimum may have a certain length in the flow direction. Or, as shown in Figure 4(D), the nozzle opening 2d may open directly from the minimum diameter portion of the throttling section 2e (without forming a region 2eii where the flow path cross-sectional area gradually increases). Furthermore, as shown in Figure 4(E), the center cone 5c of the swirler may be extended to the minimum diameter portion of the throttling section 2e to the extent that it does not reduce the degree of fuel dispersion in the mixed fluid ejected from the nozzle opening 2d. This increases the flow velocity in the throttling section, making it less likely for fluid to flow back from the combustion field 3f to the nozzle opening 2d.

[0033] Furthermore, if a swirler 5 having a center cone 5c is provided within the air passage 2x, as shown in Figure 5(A), the center cone 5c may be extended to the throttling section 2e, and the fuel passage 2φ may be formed to penetrate the center cone 5c, with a fuel outlet hole 2f opening at its tip, thereby better mixing air and fuel and reducing NOx generation. Alternatively, if the center cone 5c is extended to the throttling section 2e within the air passage 2x, as shown in Figure 5(B), the fuel passage 2φ may be formed only within the center cone 5c (the fuel passage 2φ is not formed within the peripheral wall portion 2b of the nozzle), with a fuel outlet hole 2f opening at its tip. In this case, the formation of the fuel passage 2φ becomes easier. The fuel outlet hole 2f opening at the tip of the center cone 5c may be opened along the outer circumference of the tip, as shown in Figure 5(C), so as to inject fuel radially near the tip of the center cone 5c.

[0034] The wing-shaped member 5w, which rotates the direction of the airflow of the swirler 5, may be provided at the air inlet 4a, as shown in Figure 6. The configuration in which the wing-shaped member 5w is provided at the air inlet 4a may also be applied to the configurations illustrated in Figures 4 and 5.

[0035] Addition of airflow channel In the combustion nozzle of this embodiment described above, additional air passages may be formed as described below.

[0036] First, as shown in Figure 7(A), when a swirler 5 having a center cone 5c is provided in the air passage 2x, it is also possible that an air passage is formed that penetrates the center cone 5c in the axial direction, and compressed air flows out from the tip (2g) of the center cone 5c. According to simulations by the inventors of this embodiment, when compressed air is not ejected from the tip of the center cone 5c, the temperature of the center cone 5c becomes relatively high, as shown in Figure 7(C). However, when compressed air is ejected from the tip of the center cone 5c, it was observed that the temperature of the center cone 5c decreases relatively, as shown in Figure 7(B). Therefore, in this embodiment, as depicted in Figure 7(A), by ejecting compressed air from the tip of the center cone 5c, the tip of the center cone 5c, which is easily exposed to high temperatures, can be protected from combustion heat, and the possibility of melting damage can be reduced.

[0037] Furthermore, as shown in Figure 8(A), in the combustion nozzle 2, a further air passage (internal air passage in the peripheral wall) 4b is inserted inside the peripheral wall 2b that defines the air passage 2x, parallel to the fuel passage 2φ, and air outlets 2g are provided arranged circumferentially with respect to the fuel outlet hole 2f, so that air is ejected from the surrounding air outlets 2g relative to the compressed air flowing through the air passage 2x. With this configuration, it is expected that the fuel F ejected from the fuel outlet hole 2f will be dispersed more uniformly in the compressed air. In this regard, the fuel outlet 2f and air outlet 2g in the throttling section 2e may be arranged alternately in the circumferential direction. Their orientation may be such that they extend radially toward the center of the air passage 2x, as shown in Figure 8(B), or they may be arbitrarily inclined from the radial direction toward the center of the air passage 2x, as shown in Figure 8(C). This allows the fuel flow from the fuel outlet 2f and the air flow from the air outlet 2g to collide in the compressed air flow within the air passage 2x, thereby enabling a more uniform mixing of fuel and air.

[0038] In yet another configuration, as shown in Figure 9(A), an air ejection ring 6 is fitted around the outer circumference of the combustion nozzle 2 to eject compressed air from the outer circumference of the nozzle opening 2d of the combustion nozzle 2 into the combustion field 3f, and compressed air PA may flow out from air ejection holes 6a perforated in the circumferential direction of the ring 6, as shown in Figure 9(B). With this configuration, the air and fuel are mixed more uniformly, suppressing the amount of NOx generated, and a cooling effect is also obtained on the nozzle periphery. This effect is particularly advantageous when the fuel is hydrogen, as the combustion temperature is high. The air ejection ring 6 is simply a ring with through holes, so it can be added relatively inexpensively.

[0039] Thus, in the combustion nozzle with the above configuration, the compressed air flow introduced into the nozzle is temporarily restricted to increase its velocity, and then fuel is injected (preferably from around the air flow). This allows the combustion field to be released over a relatively short distance in a more uniformly mixed state of air and fuel, resulting in a lean fuel mixture that is then burned. In the case of combustors or combustion nozzles used in conventional hydrogen gas turbines, in order to mix air and fuel to a degree that appropriately suppresses NOx generation, the fuel is either mixed with the compressed air flow, traveled a long distance, and then sent to the combustion field. Alternatively, in order to suppress the combustion temperature, the fuel and air input points are subdivided so that the flames generated in the combustion field become minute flames. As a result, the nozzle occupies a large space to accommodate numerous fuel and air supply ports, making it difficult to miniaturize the combustion nozzle or combustor. In contrast, according to the configuration of this embodiment, as described above, the fuel and air are sufficiently and uniformly mixed while traveling a relatively short distance, suppressing the occurrence of areas with locally high fuel concentrations in the combustion field, and keeping the overall fuel concentration low. As a result, the fuel temperature does not become excessively high locally or overall, and the amount of NOx generated is suppressed. Furthermore, because the compressed air flow is narrowed before reaching the nozzle opening and released into the combustion field, backflow of fluid from the combustion field (flashback) is less likely to occur, and thermal damage (melting) to the nozzle components is prevented. According to the configuration of this embodiment, the combustion nozzle can be made relatively compact, and while suppressing flashback, it is possible to uniformly mix the fuel and air and lean the mixture to suppress the amount of NOx generated. Therefore, the combustion nozzle of this embodiment can be used particularly advantageously in the combustor of a small class gas turbine that can use hydrogen as fuel.

[0040] While the above description is made in relation to embodiments of the present invention, many modifications and changes are readily possible for those skilled in the art, and it will be clear that the present invention is not limited to the embodiments illustrated above, but can be applied to various devices without departing from the concept of the present invention.

Claims

1. A combustion nozzle that injects compressed air and fuel to be burned into the combustion chamber of a gas turbine combustor, An air passage defined to receive the compressed air from an air inlet and discharge the compressed air from a nozzle opening that opens into the combustion chamber, A fuel passage is defined to receive the fuel and to flow out from the fuel outlet hole to the compressed air flow that ejects the fuel from the nozzle opening. It has, In the air passage connecting the air inlet and the nozzle opening, a throttled section is provided in which the cross-sectional area of ​​the compressed air passage is relatively small, and a fuel outlet is provided in the throttled section, so that the fuel is ejected from the fuel outlet to the compressed air flowing through the air passage. Furthermore, a combustion nozzle is configured such that an internal air passage for compressed air flows into the circumferential wall portion, which defines the air passage, and air outlet holes communicating with the internal air passage are provided circumferentially with respect to the fuel outlet hole, and a further compressed air flow is ejected from the surrounding air outlet holes in relation to the compressed air flow through the air passage.

2. A combustion nozzle according to claim 1, wherein a plurality of fuel outlet holes are arranged substantially evenly along the circumferential direction of the air passage.

3. A combustion nozzle according to claim 1 or 2, wherein a plurality of fuel outlets and air outlets are alternately arranged along the circumferential direction of the air passage.

4. A combustion nozzle according to claim 1 or 2, wherein in the throttling section, a first region is defined along the direction of compressed air flow, where the flow path cross-sectional area gradually decreases from the upstream side of the throttling section, and a second region is defined where the flow path cross-sectional area gradually increases from the downstream end of the first region toward the nozzle opening.

5. A combustion nozzle according to claim 1, wherein a swirler is provided on the upstream side of the throttling section of the air passage to cause the flow of compressed air to become a swirling flow.

6. A combustion nozzle according to claim 5, wherein the swirler comprises a center cone positioned along the central axis of the air passage that is in line with the flow direction of the compressed air, and a wing-shaped member extending radially from the center cone, the surface of which is inclined with respect to the central axis of the air passage, and the compressed air flow becomes a swirling flow as it flows along the surface of the wing-shaped member.

7. A combustion nozzle according to claim 6, wherein the ratio of the outer diameter of the center cone of the swirler to the inner diameter of the installation portion of the swirler in the air passage is less than a predetermined value.

8. A combustion nozzle according to claim 6, wherein the ratio of the outer diameter of the center cone of the swirler to the inner diameter of the installation portion of the swirler in the air passage is such that backflow of fluid from the combustion chamber into the air passage is avoided.

9. A combustion nozzle according to claim 6, wherein a flow path is formed within the center cone of the swirler, which penetrates the center cone along the central axis and has a fluid outlet hole opened at the downstream end of the center cone where the compressed air flow is located, and the compressed air is circulated within the flow path within the center cone and ejected from the fluid outlet hole toward the combustion chamber.

10. A combustion nozzle according to claim 6, wherein in the throttling section, a first region is defined along the direction of the compressed air flow, from the upstream side of the throttling section, and a second region is defined, from the downstream end of the first region toward the nozzle opening, and the center cone extends such that the downstream end of the center cone of the swirler extends to the position of the downstream end of the first region.

11. A combustion nozzle according to claim 6, wherein a flow path is formed within the center cone of the swirler, which penetrates the center cone along the central axis and has a fluid outlet hole opened at the downstream end of the center cone where the compressed air flow is located, and the fuel is flowed through the flow path within the center cone and ejected from the fluid outlet hole toward the combustion chamber.

12. A combustion nozzle according to claim 1, wherein the inner diameter of the fuel outlet hole is smaller than the flame extinguishing distance of the fuel.

13. A combustion nozzle according to claim 12, wherein the fuel is hydrogen.

14. A combustor for a gas turbine, comprising a combustion nozzle that injects compressed air and fuel to be burned into the combustion chamber, An air passage defined to receive the compressed air from an air inlet and discharge the compressed air from a nozzle opening that opens into the combustion chamber, A fuel passage is defined to receive the fuel and to flow out from the fuel outlet hole to the compressed air flow that ejects the fuel from the nozzle opening. It has, In the air passage connecting the air inlet and the nozzle opening, a throttled section is provided in which the cross-sectional area of ​​the compressed air passage is relatively small, and a fuel outlet is provided in the throttled section, so that the fuel is ejected from the fuel outlet to the compressed air flowing through the air passage. Furthermore, a combustion nozzle is configured such that an internal air passage for compressed air flows into the circumferential wall portion, which defines the air passage, and air outlet holes communicating with the internal air passage are arranged circumferentially with respect to the fuel outlet hole, and a further compressed air flow is ejected from the surrounding air outlet holes in relation to the compressed air flow through the air passage. A combustion device equipped with [a specific feature].

15. A combustor according to claim 14, wherein a plurality of fuel outlets and air outlets are alternately arranged along the circumferential direction of the air passage in the combustion nozzle.

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