Combustor suitable for hydrogen gas turbine and combustion nozzle for the same

Abstract

To provide a combustor 1 with a structure suitable for a small-class gas turbine that can use hydrogen as fuel and capable of sufficiently uniformly mixing air and hydrogen in a small space before combustion or a combustion nozzle 2 for the combustor.SOLUTION: A combustor having a combustion chamber to which compressed air and fuel to be burned in a gas turbine are ejected includes: a first air ejection hole for ejecting a first air flow of the compressed air to the combustion chamber; a second air ejection hole for ejecting a second air flow of the compressed air in a direction intersecting with the first air flow toward an approximate center of the first air flow from an approximate entire region of an outer periphery of a flow passage of the first air flow; and a fuel ejection hole for ejecting a fuel flow of fuel to an intersecting region of the first air flow and the second air flow.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a combustor of a gas turbine engine (hereinafter referred to as "gas turbine"), and a nozzle (combustion nozzle) for injecting and burning compressed air and fuel into a combustion chamber in the combustor. More specifically, the present invention relates 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 perspectives of preventing global warming and decarbonization, research and development of heat engines such as gas turbines fueled by hydrogen are underway. For example, in Patent Document 1, there is a combustor for a gas turbine that uses hydrogen and methane as fuels. Methane, which is the main fuel, is injected from a premixed combustion type main burner arranged on the upstream side of a combustion cylinder that forms a combustion chamber to form a combustion field. In this combustion field, a plurality of diffusion combustion type afterburner burners that inject fuel from the peripheral wall into the combustion chamber are provided, and a combustor is proposed that has a configuration in which hydrogen is introduced from a part of them. According to such a configuration, since the main burner is of the premixed combustion type, the amount of NOx in the high-temperature combustion gas generated in the primary combustion region on the upstream side of the combustion chamber is suppressed. Also, by dispersedly arranging the hydrogen injection amounts and the afterburner burners, the fuel concentration in the combustion region of each afterburner burner becomes thinner, and the combustion temperature of each afterburner burner is suppressed to be low as a whole, and it is said that the generation of NOx can be suppressed. Furthermore, in this configuration, by adopting a diffusion combustion type afterburner burner, the configuration has a low flashback risk. In Patent Document 2, in a gas turbine that uses a highly reactive gas such as hydrogen as fuel, as a structure of a combustor that realizes low NOx combustion, flashback prevention, and suppresses combustion vibration, a plurality of annular fuel injection units are concentrically arranged on the upstream end surface of a combustion cylinder that forms a combustion chamber. Each fuel injection unit has an annular fuel injection member having a plurality of fuel injection holes that open on the outer peripheral surface and / or the inner peripheral surface, and an annular air guide member that guides air with respect to the fuel gas injected from each fuel injection hole of the annular fuel injection member. A configuration is proposed in which at least one of a plurality of circumferentially extending circumferential isolation walls that isolate the gas passages of the annular fuel injection units at equal intervals in the circumferential direction and a radially extending radial isolation wall that isolates between two adjacent annular fuel injection units in the radial direction is provided. Furthermore, in Patent Document 3, in a gas turbine facility, in order to reduce NOx and promote the mixing of fuel and air to improve the flame stability in the combustion chamber, it is configured to supply fuel air to the combustion chamber as a plurality of coaxial jets, and an air flow is formed on the outer peripheral side thereof with the fuel flow as the center in the premixed flow path.In such a configuration, by performing premixing, lean burn can be achieved, and low NOx can be advantageously realized. However, a large space is required to create a good mixing state, and as a result, the risk of backfire due to fuel backflow can increase. Therefore, by using a plurality of nozzles, combustion is carried out in a narrow space in a short time to suppress backfire. Although the fuel in the configuration of this document is not limited to hydrogen, it forms the basic configuration of the subsequent structures related to hydrogen combustion. In Patent Document 4, in a gas turbine combustor, in order to achieve stable combustion and maintain low NOx combustion performance, a plurality of air holes are formed in a concentric row on the upstream side of the combustion chamber, and a plurality of fuel nozzles for supplying fuel from the upstream side of each air hole are arranged. A plurality of porous coaxial jet burners are provided, and on the upstream side side wall of the combustion chamber, a plurality of combustion chamber side wall air holes having an ejection direction facing the central axis of the combustion chamber are also arranged, and fuel nozzles for supplying fuel coaxially to each of such air holes are arranged. A configuration in which a plurality of combustion chamber side wall coaxial jet burners are arranged at predetermined intervals in the circumferential direction of the combustion chamber side wall has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Hydrogen is prone to generating NOx because it has a higher combustion temperature compared to hydrocarbon fuels that have been commonly used until now. Therefore, in the configuration of the combustor of a gas turbine (hydrogen gas turbine) using hydrogen as fuel, an issue is how to appropriately mix the fuel and air before combustion so as not to create a region with a locally high fuel concentration (when the fuel concentration is high, the combustion temperature becomes high), in order to achieve low NOx emissions. Regarding this point, the configurations for low NOx emissions in conventional combustors for hydrogen gas turbines, such as those exemplified above, are targeted at medium and large-sized gas turbines for power generation with a power generation capacity exceeding 1 MW. Their structures are somewhat complex, with a large number of components and requiring a large space, so it is difficult to apply them to combustors for small gas turbines with a power generation capacity of several tens of kW. Therefore, it would be advantageous to have a combustor or combustion nozzle with a novel structure that can sufficiently and uniformly mix air and hydrogen before combustion and is applicable to combustors for small gas turbines.

[0005] Thus, the main subject of the present invention is to provide a combustor or combustion nozzle for a small-class gas turbine that can utilize hydrogen as fuel.

[0006] Another subject of the present invention is to provide a combustor or combustion nozzle that can be used for a small-class gas turbine as described above, and has a novel structure that can sufficiently and uniformly mix air and hydrogen before combustion within a small space.

Means for Solving the Problems

[0007] According to one aspect of the present invention, the above problems are solved by a combustor having a combustion chamber into which compressed air to be combusted and fuel are ejected, a first air ejection hole for ejecting a first air flow of the compressed air into the combustion chamber, a second air ejection hole for ejecting a second air flow of the compressed air in a direction intersecting the first air flow from substantially the entire outer periphery of the flow path of the first air flow toward the approximate center of the first air flow, a fuel injection hole that injects a fuel flow of the fuel into an intersection region between the first air flow and the second air flow is achieved by a combustor having the same.

[0008] According to another aspect of the present invention, the above problem is solved by a combustion nozzle that injects compressed air and fuel to be burned into a combustion chamber of a combustor of a gas turbine, a first air injection hole that injects a first air flow of the compressed air into the combustion chamber, a second air injection hole that injects a second air flow of the compressed air in a direction intersecting the first air flow from substantially the entire outer periphery of the flow path of the first air flow toward substantially the center of the first air flow, a fuel injection hole that injects a fuel flow of the fuel into an intersection region between the first air flow and the second air flow is achieved by a combustion nozzle having the same.

[0009] In the above configuration, the "combustor" in a gas turbine is a combustor that defines a combustion chamber in which compressed air and fuel are ejected, mixed, and burned to generate combustion gas that rotates the turbine of the compressor. The "combustion nozzle" is a nozzle that ejects compressed air and fuel to be burned into the combustion chamber of the combustor as described above. Typically, the "first air injection hole", "second air injection hole", and "fuel injection hole" are formed in the combustion nozzle, and the second air injection hole provided along the outer periphery of the flow path of the first air flow may be formed in the liner of the combustor that defines the combustion chamber.

[0010] The features of the combustor or combustion nozzle of the present invention are, as described above, that along the outer periphery of the flow path of the first air flow ejected from the first air ejection hole, the second air ejection hole is arranged, and the second air flow ejected from the second air ejection hole is formed so as to cross the first air flow from substantially the entire outer periphery of the first air flow toward the approximate center of the first air flow, that is, from the outer periphery of the first air flow radially inward of the flow path of the first air flow. Then, from the fuel injection hole, a fuel flow is injected toward the region where the first air flow and the second air flow cross. According to such a configuration, when the compressed air and the fuel are ejected into the combustion chamber, the fuel flow enters the intersection region of the first air flow and the second air flow, so that the fuel is not blown off in any direction from any air flow, and due to the action of the turbulent flow generated by the collision of the first air flow and the second air flow, the fuel flow is dispersed into the air flow, and without requiring a large space, the air and the fuel are quickly and sufficiently mixed. As a result, the generation of a region where the combustion temperature becomes locally high is suppressed, and even in a combustor for a small gas turbine, low NOx can be achieved.

[0011] In the configuration of the above-described combustor or combustion nozzle, the first air ejection hole is formed in a substantially circular shape, the flow path of the first air flow is formed in a columnar shape, and the second air ejection hole may be provided (in a slit shape or a dot array shape) so as to surround the columnar flow path of the first air flow and extend over its outer periphery. Further, in order for the fuel to be evenly dispersed in the circumferential direction of the first air flow, it is preferable that the plurality of fuel injection holes are arranged substantially evenly along the outer periphery of the flow path of the first air flow.

[0012] Also, the ejection direction of the air flow of the second air ejection hole is the direction that crosses the flow path of the first air flow as described above. Preferably, the ejection direction of the air flow of the second air ejection hole may be directed so that the first air flow and the second air flow cross substantially perpendicularly. As a result, it is expected that the air and the fuel are more effectively and quickly and sufficiently mixed. Further, the first air flow and the second air flow may be ejected so that their flow rates are substantially equal. As a result, it is expected that the air and the fuel are quickly and sufficiently mixed.

[0013] Furthermore, in the configuration of the above-described combustor or combustion nozzle, at least one of the first air flow and the second air flow is formed into a swirling flow so as to effectively generate turbulence in the collision region between the first air flow and the second air flow, and the fuel in the fuel flow entering that region is more favorably mixed into the air flow. The first air ejection hole and the second air ejection hole may be formed in such a manner. The method of making the first air flow or the second air flow into a swirling flow may be achieved in any manner. The first air flow may be a swirling flow and the second air flow may be a straight flow, or vice versa. Both the first air flow and the second air flow may be swirling flows (it is preferable that the swirling directions of the first air flow and the second air flow are opposite). The imparting of the component advancing in the circumferential direction in the first air flow can be achieved, for example, by arranging a swirler in the flow path upstream of the first air ejection hole, or by providing an intake flow path for compressed air in the flow path upstream of the first air ejection hole such that compressed air flows in along the circumferential direction of the inner diameter of the flow path. The imparting of the component advancing in the circumferential direction in the second air flow can be achieved by tilting the flow path in the circumferential direction at the second air ejection hole.

[0014] In the configuration of the above-described combustor or combustion nozzle, in order to prevent "backfire" in which combustion flows backward through the fuel flow path, the fuel ejection hole for ejecting the fuel flow may be formed such that its inner diameter is smaller than the extinction distance of the fuel. When the fuel is hydrogen, the extinction distance is about 0.64 mm, so the aperture diameter of the fuel ejection hole may be, for example, 0.6 mm or less.

Advantages of the Invention

[0015] Thus, in the combustor or combustion nozzle of the gas turbine of the present invention, when the compressed air flow and the fuel flow are ejected into the combustion chamber, a sufficiently more uniform mixing of the fuel with respect to the compressed air flow can be achieved at a relatively short distance. Therefore, it can be used as a combustion nozzle for a small-sized class gas turbine combustor with suppressed NOx generation even when using a fuel with a high combustion temperature such as hydrogen. The combustor and combustion nozzle of the present invention can be used for a gas turbine using hydrogen as fuel, which is miniaturized so as to be mountable on vehicles such as automobiles. As a result, a wider spread of hydrogen gas turbines is expected.

[0016] 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

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Description of Reference Numerals

[0018] 1... combustor, 2... combustion nozzle, 2a... fuel supply pipe, 2b... nozzle peripheral wall portion, 2c... first air ejection hole, 2d... nozzle opening, 2e... second air ejection hole, 2f... fuel outflow hole, 2g... flow guide vane plate, 2x... air flow path, 2φ... fuel flow path, 3... combustion chamber, 3f... combustion field, 3h... combustion chamber housing (peripheral wall), 3o... combustion chamber opening, 3x... second air ejection hole, 4... compressed air supply ring, 4a... air flow inlet, 5... swirler, 5c... swirler center cone, 5w... swirler wing-shaped member, F, Ff... fuel flow, PA... compressed air flow, Af1... first air flow, Af2... second air flow

Best Mode for Carrying Out the Invention

[0019] Basic configuration of combustor and combustion nozzle The combustor according to this embodiment is advantageously used in a combustor of a gas turbine that uses, as fuel, a substance that is lighter in mass and has a higher combustion temperature than hydrogen or other hydrocarbon-based substances that have been used conventionally. As shown in FIG. 1(A), in the combustor 1 of the gas turbine, the combustion nozzle 2 is installed at the opening 3o of the housing 3h of the combustion chamber 3 that defines the combustion field 3f. To put it simply, compressed air PA flows into the combustion nozzle 2 from a compressor (not shown) connected to a turbine (not shown) through an annular compressed air supply ring 4 defined on the outer periphery of the combustion chamber 3, and fuel F flows in from a fuel tank (not shown) through a fuel supply pipe 2a. They are mixed and discharged into the combustion field 3f to be combusted.

[0020] In terms of its specific configuration, the combustion nozzle 2 may have a substantially cylindrical peripheral wall portion 2b formed with a flange 2h or the like, and is fitted into the opening 3o of the combustion chamber housing 3h so that the end face where the nozzle opening 2d is located faces the combustion field 3f. In the nozzle opening 2d of the combustion nozzle 2, a first air ejection hole 2c is formed in a substantially central region thereof, and a slit-shaped (or dot array-shaped) second air ejection hole 2e is formed so as to surround the periphery thereof. A plurality of fuel injection holes 2f may be arranged substantially evenly between the first air ejection hole 2c and the second air ejection hole 2e (see FIG. 4(A)). The first air ejection hole 2c, the fuel injection hole 2f, and the second air ejection hole 2e may be arranged concentrically in this order so as to eject compressed air and fuel more evenly in space. And as understood from FIG. 1(C), the compressed air flow PA sent through the compressed air supply ring 4 flows into the air flow path 2x from the air inlet 4a. A part of it is ejected from the first air ejection hole 2c, and another part is ejected from the second air ejection hole 2e, respectively, in the manner described later. Further, the fuel supplied through the fuel flow path 2φ inside the fuel supply pipe 2a is ejected from the fuel injection holes 2f between the first air ejection hole 2c and the second air ejection hole 2e in the manner described later. The injection amount of the fuel is adjusted so that the combustion temperature becomes an equivalence ratio of 1500°C or lower.

[0021] As another aspect of the present embodiment, as schematically depicted in FIG. 2, the air flow ejected from the second air ejection hole 2e among the compressed air may instead be ejected from an air ejection hole 3x formed in the opening 3o of the housing 3h outside the combustion nozzle 2. In this case, in the combustion nozzle 2, it is not necessary to form the second air ejection hole 2e, and the manufacture of the combustion nozzle 2 becomes easier.

[0022] In any of the above configurations, the aperture diameter of the fuel injection hole 2f is designed to be smaller than the flame extinction distance of the fuel in order to prevent flashback. Specifically, since the flame extinction distance of hydrogen is about 0.64 mm, when the fuel is hydrogen, the aperture diameter of the fuel ejection hole 24 may be, for example, 0.6 mm or less.

[0023] Ejection mode of air flow and fuel flow As described in the "Summary of the Invention" section, hydrogen has a higher combustion temperature and is more likely to generate NOx compared to hydrocarbon fuels that have been commonly used so far. Therefore, in the configuration of the combustor used in a hydrogen gas turbine, in the fuel-air mixture, it is required to make the fuel concentration as uniform as possible in the mixing process from the input of fuel and air to before combustion so that a region where the fuel concentration becomes locally high and the combustion temperature becomes high does not occur. In particular, in the case of a small gas turbine, since the space from the air and fuel inlets to the combustion field in the combustor is small, it is preferable that the fuel can be made uniform in the air as quickly as possible. In this regard, for example, as shown in FIG. 6, when hydrogen fuel Ff is injected around the compressed air flow (primary air flow) Af ejected from the approximate center of the combustion nozzle toward the combustion field, and local air flows As are added locally from several locations along the periphery thereof, it has been observed that a region where the fuel concentration (hydrogen concentration) becomes locally high (spiral arrows in the figure) is formed around the primary air flow Af.

[0024] Therefore, when the inventors of the present embodiment conducted various studies on the modes of ejection of the air flow and the fuel flow in the combustion chamber, as schematically depicted in FIGS. 3(A) and 3(B), with respect to the air flow (first air flow) Af1 ejected from the substantially central region (2c) of the combustion nozzle 2 toward the combustion field 3f, another air flow (second air flow) Af2 is ejected from the entire outer periphery of the air flow toward its approximate center, that is, the second air flow Af2 is ejected radially inward from the outer periphery of the first air flow Af1, and the first air flow Af1 and the second air flow Af2 are made to intersect and collide, and the fuel flow Ff is made to penetrate into the intersection region. It has been found that the fuel is more rapidly and evenly dispersed in the air, and it becomes difficult to form a region with a locally high fuel concentration. Specifically, as shown in the results of FIG. 5, it was observed that the fuel flow injected into the intersection region of the first air flow Af1 and the second air flow Af2 was rapidly dispersed along its traveling direction (it was observed that the equivalence ratio of H2 decreased rapidly along the flow direction from the injection position of the fuel flow). This is considered to be due to the action of the turbulent flow formed in the intersection region of the first air flow Af1 and the second air flow Af2. Thus, in the present embodiment, as described above, with respect to the first air flow Af1 ejected toward the combustion chamber, the second air flow Af2 is ejected from substantially the entire outer periphery thereof toward its approximate center in a direction intersecting the first air flow Af1, and the first air ejection hole 2c, the second air ejection hole 2e, and the fuel ejection hole 2f are formed so that the fuel flow Ff of the fuel is ejected into the intersection region of the first air flow and the second air flow.

[0025] In the mode of ejecting the second air flow Af2 in a direction intersecting the first air flow Af1 and ejecting the fuel flow Ff toward the intersection region as described above, the angle (intersection angle) θ of the direction of the second air flow Af2 with respect to the direction of the first air flow Af1 may be adjusted as appropriate. Preferably, the intersection angle θ may be perpendicular (in order to increase the turbulent flow action caused by the collision of the two air flows). Also, the ratio of the flow rates of the first air flow Af1 and the second air flow Af2 may be adjusted as appropriate. Preferably, they may be made approximately equal (in order to make it difficult for the fuel flow to stay on either side of the air flow).

[0026] Swirling of compressed air flow In the above-described combustor, more preferably, as schematically shown in FIG. 4(A), at least one or both of the first air flow Af1 and the second air flow Af2 may be formed into swirling flows so that turbulence is likely to be generated by the collision between the first air flow Af1 and the second air flow Af2. When both the first air flow Af1 and the second air flow Af2 are swirled, their swirling directions are preferably opposite to each other.

[0027] The first air flow Af1 may be formed into a swirling flow by any configuration. For example, inside the air flow path 2x upstream of the first air ejection hole 2c, as schematically shown in FIG. 4(B), there may be arranged a swirler 5 having a shape like a non-rotating screw having a center cone 5c extending along the approximate center of the air flow path 2x and a plurality of wing-like members 5w extending radially around the center cone 5c. In such a swirler 5, the surfaces of the plurality of wing-like members 5w are inclined with respect to the central axis of the air flow path, whereby when the compressed air flow flows along the surface of the wing-like member 5w, the flow direction rotates and a swirling flow is formed. Note that the wing-like member 5w that rotates the direction of the air flow of the swirler 5 may be provided at the air flow inlet 4a. The configuration for swirling the second air flow Af2 can be achieved, for example, as schematically shown in FIG. 4(A), by providing flow guide vanes 2g that tilt the direction of the air flow passing therethrough at appropriate intervals in the second air ejection hole 2e.

[0028] Thus, in the combustion nozzle having the above-described series of configurations and the combustor including the same, when injecting compressed air and fuel into the combustion chamber, the compressed air flow is divided into two and made to collide with each other, and a fuel flow is introduced into the collision region, so that the fuel flow is not blown away in one direction, and the fuel is rapidly dispersed into the compressed air by the action of the turbulent flow generated in the air flow. In such a configuration, since the fuel and the compressed air can be mixed immediately after being injected into the combustion chamber, there is no need for a space for premixing the fuel and the compressed air as in the prior art, and the fuel is more evenly dispersed in the compressed air, and it is expected that low NOx can be achieved.

[0029] The configuration of the present embodiment is a gas turbine that uses hydrogen as fuel, and in particular, it is advantageously applicable to the combustor and the combustion nozzle of a small gas turbine, for example, a small gas turbine in the order of several tens of kW.

[0030] The above description has been made in relation to the embodiments of the present invention, but many modifications and changes are easily possible for those skilled in the art, and the present invention is not limited to only the embodiments illustrated above, and it will be apparent that the present invention can be applied to various devices without departing from the concept of the present invention.

Claims

1. A combustor having a combustion chamber into which compressed air and fuel to be burned in a gas turbine are ejected, a first air ejection hole for ejecting a first air flow of the compressed air into the combustion chamber, a second air ejection hole for ejecting a second air flow of the compressed air in a direction intersecting the first air flow from substantially the entire outer periphery of the flow path of the first air flow toward substantially the center of the first air flow, and a fuel ejection hole for ejecting a fuel flow of the fuel into an intersection region between the first air flow and the second air flow The combustor having the above.

2. The combustor according to Claim 1, wherein the second air ejection hole is arranged such that the second air flow intersects the first air flow substantially perpendicularly.

3. The combustor according to Claim 1, wherein the first air ejection hole and the second air ejection hole are formed such that at least one of the first air flow and the second air flow becomes a swirling flow.

4. The combustor according to Claim 1, wherein the flow rates of the first air flow and the second air flow are substantially equal.

5. A combustion nozzle for ejecting compressed air and fuel to be burned into a combustion chamber of a combustor of a gas turbine, a first air ejection hole for ejecting a first air flow of the compressed air into the combustion chamber, a second air ejection hole for ejecting a second air flow of the compressed air in a direction intersecting the first air flow from substantially the entire outer periphery of the flow path of the first air flow toward substantially the center of the first air flow, and a fuel ejection hole for ejecting a fuel flow of the fuel into an intersection region between the first air flow and the second air flow The combustion nozzle having the above.

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