Combustion nozzle

Abstract

To provide a combustion nozzle capable of achieving both reduction of NOx emission and prevention of flashback.SOLUTION: A combustion nozzle 1 jets compressed air and a fuel to be burned into a combustion chamber of a gas turbine combustor. The combustion nozzle 1 comprises: an air channel for flowing out compressed air into the combustion chamber from the combustion nozzle 1 that opens toward the combustion chamber; and a fuel channel for flowing out the fuel into the air channel. The combustion nozzle 1 has a shape that enlarges toward the combustion chamber.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the technical field of combustion nozzles.

Background Art

[0002] As an apparatus using this type of combustion nozzle, a gas turbine using hydrogen as fuel has been proposed (see Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] When attempting to use hydrogen as fuel for a gas turbine, hydrogen has a higher combustion temperature than hydrocarbon fuels that have been commonly used until now, so NOx is likely to be generated. Also, hydrogen has a faster combustion speed than hydrocarbon fuels, and the extinction distance of hydrogen (0.64 mm) is shorter than that of hydrocarbon fuels (about 2 mm), so flashback where combustion flows backward through the fuel flow path is likely to occur.

[0005] The present invention has been made in view of the above problems, for example, and an object thereof is to provide a combustion nozzle capable of achieving both reduction of NOx emissions and prevention of flashback.

Means for Solving the Problems

[0006] A combustion nozzle according to an aspect of the present invention is a combustion nozzle that ejects compressed air and fuel to be burned into a combustion chamber of a combustor of a gas turbine. The combustion nozzle has an air flow path through which compressed air flows out from the combustion nozzle that opens toward the combustion chamber into the combustion chamber, and a fuel flow path through which fuel flows out with respect to the air flow path. The shape of the combustion nozzle is a shape that expands toward the combustion chamber.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0008] An embodiment related to a combustion nozzle will be described with reference to FIGS. 1 to 4. In the embodiment, hydrogen is cited as an example of the fuel. However, the fuel is not limited to hydrogen. The configuration of the combustion nozzle 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a combustion nozzle according to the embodiment. FIG. 2 is a sectional view taken along line A-A of FIG. 1.

[0009] In FIGS. 1 and 2, the combustion nozzle 1 has a nozzle opening 1a. The combustion nozzle 1 is arranged such that the nozzle opening 1a is in contact with a combustion chamber (for example, the combustion chamber 30 shown in FIG. 3) of a combustor of a gas turbine using, for example, hydrogen gas as fuel. As shown in FIG. 2, the diameter of the nozzle opening 1a becomes larger as it approaches the end of the combustion nozzle 1 (the left end of the combustion nozzle 1 in FIG. 2).

[0010] The combustion nozzle 1 has air holes 11. Compressed air is supplied to the combustion nozzle 1 from the outside through the air holes 11. The combustion nozzle 1 has a swirler 12 through which the compressed air supplied through the air holes 11 passes. The swirler 12 is an annular member in which a plurality of stationary vanes are arranged in the circumferential direction. The swirler 12 may have a center cone 12a extending along the central axis of the combustion nozzle 1 and a plurality of wing-like members 12b (corresponding to the plurality of stationary vanes described above) extending radially from the center cone 12a. Incidentally, the swirler 12 may be referred to as an air swirler. Incidentally, in FIG. 2, the nozzle port 1a may mean a region to the left of the end of the center cone 12a.

[0011] The combustion nozzle 1 has a fuel supply pipe 21, a fuel supply passage 22, and a fuel supply hole 23. As shown in FIGS. 1 and 2, the fuel supply hole 23 opens into the nozzle port 1a. Hydrogen gas as fuel is supplied from the fuel supply hole 23 to the nozzle port 1a through the fuel supply pipe 21 and the fuel supply passage 22.

[0012] The air flow and the fuel flow will be described with reference to FIG. 3. FIG. 3 is a diagram showing the air flow and the fuel flow. In FIG. 3, the combustion nozzle 1 is arranged such that the nozzle port 1a is in contact with the combustion chamber 30 of the combustor of the gas turbine. An air supply pipe 40 is connected to the air supply hole 11 of the combustion nozzle 1.

[0013] In FIG. 3, the solid arrows indicate the air flow, and the dotted arrows indicate the fuel flow. As shown in FIG. 3, the compressed air supplied to the combustion nozzle 1 from the air supply pipe 40 through the air supply hole 11 is supplied to the nozzle port 1a through the swirler 12. As described above, hydrogen gas is supplied from the fuel supply hole 23 to the nozzle port 1a through the fuel supply pipe 21 and the fuel supply passage 22. The compressed air and the hydrogen gas may be mixed in the region indicated by the broken-line circle C (that is, near the boundary between the nozzle port 1a and the combustion chamber 30).

[0014] It can be said that the air supply holes 11, the swirls 12, and the nozzle openings 1a of the combustion nozzle 1 constitute part of the air flow path. Therefore, it can be said that the combustion nozzle 1 is provided with an air flow path. Similarly, it can be said that the fuel supply pipe 21, the fuel supply path 22, and the fuel supply holes 23 of the combustion nozzle 1 constitute part of the flow path of hydrogen gas (i.e., fuel). Therefore, it can be said that the combustion nozzle 1 is provided with a fuel flow path. As is clear from FIGS. 2 and 3, in the fuel nozzle 1, the fuel supply holes 23 are formed on the downstream side of the air flow path rather than the air supply holes 11.

[0015] As described above, the diameter of the nozzle opening 1a increases as it approaches the end of the combustion nozzle 1 (the left end of the combustion nozzle 1 in FIG. 2). Therefore, the air flow path in the combustion nozzle 1 expands toward the combustion chamber 30. That is, the air flow path in the combustion nozzle 1 gradually increases from the upstream side to the downstream side. Therefore, it can be said that the shape of the combustion nozzle 1 is a shape that expands toward the combustion chamber 30. In other words, the combustion nozzle 1 has a shape that expands toward the combustion chamber 30.

[0016] (Technical effect) As described above, in the combustion nozzle 1, the flow path expands toward the combustion chamber 30. Therefore, in the region indicated by the broken-line circle C in FIG. 3, compressed air (i.e., air with high density) can be actively collided with hydrogen gas as fuel. As a result, air and hydrogen gas can be efficiently mixed. Here, an explanation will be added with reference to FIG. 4. FIG. 4 is a diagram showing an example of the temperature distribution during combustion. As shown in FIG. 4, the inside of the combustion chamber 30 is at a relatively high temperature as a whole. This is evidence that air and hydrogen gas are properly mixed.

[0017] The flame temperature during the combustion of hydrogen gas is relatively high (for example, 2000 degrees Celsius or higher). Therefore, if the mixing of air and hydrogen gas is insufficient and there are locally rich air-fuel ratio areas, the NOx emission will increase. In contrast, in the combustion nozzle 1, air and hydrogen gas are properly mixed, so the NOx emission can be reduced. Incidentally, in the combustion nozzle 1, compressed air and hydrogen gas may be supplied so that the air-fuel ratio becomes lean. With such a configuration, the NOx emission can be further reduced.

[0018] By the way, in order to reduce the NOx emission, a premixed combustion method in which air and fuel (for example, hydrogen gas) are premixed has been proposed. Since the combustion speed of hydrogen gas is extremely fast, in the premixed combustion method, flashback where the flame runs back to the unburned gas (that is, the premixed gas) is likely to occur. In contrast, in the combustion nozzle 1, compressed air and hydrogen gas are separately supplied to the nozzle port 1a (moreover, the combustion chamber 30). That is, the combustion nozzle 1 is a combustion nozzle of the diffusion combustion method.

[0019] The diffusion combustion method is less likely to cause flashback compared to the premixed combustion method. Here, an explanation will be added with reference to FIG. 4. In the example shown in FIG. 4, although there is a relatively high-temperature region near the end of the center cone 12a in the combustion nozzle 1, it can be said that the inside of the combustion nozzle 1 is kept at a relatively low temperature. This is evidence that there is no flame intrusion due to flashback in the combustion nozzle 1.

[0020] From the above, according to the combustion nozzle 1, the mixing of air and hydrogen gas as fuel can be promoted, and the NOx emission can be reduced. According to the combustion nozzle 1, damage to parts and deterioration of part life due to flashback can be suppressed. That is, according to the combustion nozzle 1, it is possible to achieve both reduction of NOx emission and prevention of flashback.

[0021] The aspects of the invention derived from the embodiments described above will be described below.

[0022] A combustion nozzle according to one aspect of the invention is a combustion nozzle that ejects compressed air and fuel to be burned into a combustion chamber of a combustor of a gas turbine. The combustion nozzle has an air flow path through which compressed air flows out from the combustion nozzle that opens toward the combustion chamber into the combustion chamber, and a fuel flow path through which fuel flows out with respect to the air flow path. The shape of the combustion nozzle is a shape that expands toward the combustion chamber.

[0023] The combustion nozzle has a nozzle opening that opens toward the combustion chamber, and the nozzle opening has a shape that expands toward the combustion chamber. Here, the nozzle opening constitutes a part of the air flow path, and the air flow path gradually increases from the upstream side toward the downstream side.

[0024] The present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the gist or idea of the invention that can be read from the claims and the entire specification. A combustion nozzle with such modifications is also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0025] 1... Combustion nozzle, 1a... Nozzle opening, 11... Air supply hole, 12... Swirler, 21... Fuel supply pipe, 22... Fuel supply path, 23... Fuel supply hole

Claims

1. A combustion nozzle that injects compressed air and fuel to be combusted into a combustion chamber of a gas turbine combustor, an air flow path through which compressed air flows out from the combustion nozzle opening toward the combustion chamber, a fuel flow path through which fuel flows out with respect to the air flow path, comprising: the shape of the combustion nozzle is a shape that expands toward the combustion chamber A combustion nozzle characterized by this.

2. The combustion nozzle has a nozzle opening that opens toward the combustion chamber, the nozzle opening has a shape that expands toward the combustion chamber The combustion nozzle according to claim 1, characterized by this.

3. The nozzle opening constitutes a part of the air flow path, the air flow path gradually increases from the upstream side toward the downstream side The combustion nozzle according to claim 2, characterized by this.

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