KR102011903B1 - Fuel nozzle, combustor and gas turbine having the same - Google Patents

Abstract

The present invention relates to a fuel nozzle, a combustor and a gas turbine including the same,
A fuel nozzle according to an embodiment of the present invention includes an injection cylinder extending in one direction and supplying a fuel fluid to a combustion chamber; A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder; A swirler formed between the injection cylinder and the shroud; An injector module inserted into the injection cylinder. Here, the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.
According to the embodiments of the present invention, in use, it is possible to maintain a tight sealing between the injector module and the injection cylinder in a high temperature environment during combustion, and when the operation stops, the fastening state of the injector module and the injection cylinder is loosened and easily detachable. It works.

Description

FUEL NOZZLE, COMBUSTOR AND GAS TURBINE HAVING THE SAME}

The present invention relates to a fuel nozzle, a combustor and a gas turbine comprising the same.

The gas turbine is a power engine that mixes and burns compressed air and fuel compressed in a compressor, and rotates the turbine with hot gas generated by combustion. Gas turbines are used to drive generators, aircraft, ships and trains.

Gas turbines generally include compressors, combustors, and turbines. The compressor sucks and compresses the outside air and delivers it to the combustor. The compressed air in the compressor is at high pressure and high temperature. The combustor mixes and combusts compressed air and fuel introduced from the compressor. The combustion gases generated by the combustion are discharged to the turbine. The combustion gas causes the turbine blades inside the turbine to rotate, thereby generating power. The generated power is used in various fields such as power generation and driving of mechanical devices.

Republic of Korea Patent Publication No. 10-2006-0096319 (Name: Can type combustor)

An object of the present invention is to provide a hermetic sealing in a high temperature environment at the time of use, and to easily detachable fuel nozzles at the time of shutdown, a combustor and a gas turbine including the same.

Fuel nozzle according to an embodiment of the present invention, the injection cylinder is formed extending in one direction for supplying a fuel fluid to the combustion chamber; A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder; A swirler formed between the injection cylinder and the shroud; An injector module inserted into the injection cylinder. Here, the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.

In the fuel nozzle according to an embodiment of the present invention, the injector module may include an injector and a coupling part formed of a material corresponding to the outer shape of the injector and having a second thermal expansion coefficient.

In the fuel nozzle according to the exemplary embodiment of the present invention, the outer circumferential surface of the coupling portion may be formed in a thread shape, and the inner circumferential surface of the coupling portion may be formed in a shape corresponding to the outer shape of the injector.

In the fuel nozzle according to an embodiment of the present invention, the coupling portion may be integrally formed with the injector.

In the fuel nozzle according to an embodiment of the present invention, the second thermal expansion rate may be greater than the first thermal expansion rate.

In the fuel nozzle according to an embodiment of the present invention, a liquid flow path through which liquid fuel flows is formed inside the injection cylinder, and the liquid flow path communicates with the injector module.

A combustor according to an embodiment of the present invention includes a combustion chamber assembly including a combustion chamber in which fuel fluid is combusted; And a fuel nozzle assembly comprising a plurality of fuel nozzles for injecting fuel fluid into the combustion chamber. The fuel nozzle includes an injection cylinder extending in one direction and supplying a fuel fluid to the combustion chamber; A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder; A swirler formed between the injection cylinder and the shroud; An injector module is inserted into the injection cylinder, wherein the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.

In the combustor according to an embodiment of the present invention, the injector module may include an injector and a coupling part formed of a material corresponding to the outer shape of the injector and having a second coefficient of thermal expansion.

In the combustor according to an embodiment of the present invention, the outer circumferential surface of the coupling portion may be formed in a thread shape, and the inner circumferential surface of the coupling portion may be formed in a shape corresponding to the outer shape of the injector.

In the combustor according to an embodiment of the present invention, the coupling part may be integrally formed with the injector.

In the combustor according to an embodiment of the present invention, the second thermal expansion rate may be greater than the first thermal expansion rate.

In the combustor according to an embodiment of the present invention, a liquid flow path through which liquid fuel flows is formed inside the injection cylinder, and the liquid flow path communicates with the injector module.

Gas turbine according to an embodiment of the present invention, a compressor for compressing the incoming air; A combustor for mixing and combusting compressed air and fuel in a compressor; And a turbine for generating power from the gas combusted in the combustor. The combustor may include a combustion chamber assembly including a combustion chamber in which fuel fluid combusts; And a fuel nozzle assembly comprising a plurality of fuel nozzles for injecting fuel fluid into the combustion chamber. The fuel nozzle includes an injection cylinder extending in one direction and supplying a fuel fluid to the combustion chamber; A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder; A swirler formed between the injection cylinder and the shroud; An injector module is inserted into the injection cylinder, wherein the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.

In the gas turbine according to an embodiment of the present invention, the injector module may include an injector and a coupling part formed of a material corresponding to the outer shape of the injector and having a second coefficient of thermal expansion.

In the gas turbine according to an embodiment of the present invention, the outer circumferential surface of the coupling portion may be formed in a thread shape, and the inner circumferential surface of the coupling portion may be formed in a shape corresponding to the outer shape of the injector.

In the gas turbine according to an embodiment of the present invention, the coupling part may be integrally formed with the injector.

In the gas turbine according to an embodiment of the present invention, the second thermal expansion rate may be greater than the first thermal expansion rate.

According to the embodiments of the present invention, in use, it is possible to maintain a hermetic sealing between the injector module and the injection cylinder in a high temperature environment during combustion, and when the operation stops, the fastening state of the injector module and the injection cylinder is loosened and easily detachable. It works.

1 is a view showing the inside of a gas turbine according to an embodiment of the present invention.
2 is a view showing a combustor according to an embodiment of the present invention.
3 is a perspective view showing a fuel nozzle according to an embodiment of the present invention.
4 is a cross-sectional view showing a fuel nozzle according to an embodiment of the present invention.
5 is an enlarged cross-sectional view of an end portion of a fuel nozzle according to an exemplary embodiment of the present invention.
6 and 7 are cross-sectional views showing the injector module in the fuel nozzle according to an embodiment of the present invention.

Hereinafter, a fuel nozzle, a combustor and a gas turbine including the same according to the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like numbers refer to like elements in the figures.

In addition, throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, except to exclude other components unless specifically stated otherwise. In addition, throughout the specification, "on" means to be located above or below the target portion, and does not necessarily mean to be located above the gravity direction.

1 is a view showing the inside of a gas turbine according to an embodiment of the present invention, Figure 2 is a view showing a combustor according to an embodiment of the present invention, Figure 3 is according to an embodiment of the present invention A fuel nozzle is shown in perspective view.

1 to 3, the gas turbine according to an embodiment of the present invention is a compressor 1100 for compressing the incoming air to a high pressure, a combustor 1200 for mixing and burning the compressed air and fuel compressed from the compressor And a turbine 1300 for generating rotational force with combustion gas generated from the combustor. In this specification, the upstream and downstream of the fuel or air flow is defined.

The thermodynamic cycle of the gas turbine can ideally follow the Brayton cycle. The Brayton cycle consists of four processes: isotropic compression (thermal insulation compression), static pressure quenching, isotropic expansion (thermal insulation expansion), and constant pressure heat dissipation. That is, the air is inhaled and compressed to high pressure, and the fuel is combusted in a constant pressure environment to release thermal energy. The high-temperature combustion gas is expanded and converted into kinetic energy, and the exhaust gas containing residual energy is released into the atmosphere. . That is, the cycle consists of four processes: compression, heating, expansion, and heat dissipation. The description of the present invention can be widely applied to a turbine engine having a configuration equivalent to that of the gas turbine 1000 illustrated by way of example in FIG. 1.

The compressor 1100 of the gas turbine is a part that sucks and compresses air, and supplies combustion air to the combustor 1200 while supplying cooling air to a high temperature region requiring cooling in the gas turbine. . Since the sucked air is subjected to adiabatic compression in the compressor 1100, the pressure and temperature of the air passing through the compressor 1100 are increased.

The compressor 1100 constituting the gas turbine may be designed as a centrifugal compressor or an axial compressor. In a small gas turbine, a centrifugal compressor is applied, whereas a large gas turbine compresses a large amount of air. It is common to apply a multistage axial compressor as shown in FIG.

The compressor 1100 is driven using a portion of the power output from the turbine 1300. To this end, as shown in FIG. 1, the rotating shaft of the compressor 1100 and the rotating shaft of the turbine 1300 are directly connected to each other.

The combustor 1200 mixes the compressed air supplied from the outlet of the compressor 1100 with the fuel and isostatically burns to produce a high energy combustion gas.

The combustor 1200 is disposed downstream of the compressor 1100 and includes a plurality of burner modules 1210 disposed in an annular shape about a rotation axis. The burner module 1210 includes a combustion chamber assembly 1220 including a combustion chamber 1240 in which fuel fluid combusts, and a fuel nozzle assembly 1230 including a plurality of fuel nozzles for injecting fuel fluid into the combustion chamber 1240. can do.

Gas turbines and liquid fuels, or combination fuels in combination thereof may be used in the gas turbine, and the fuel fluid in the present invention means them. It is important to create a combustion environment to reduce the amount of emission gas such as carbon monoxide and nitrogen oxide, which are legally regulated. Although combustion control is relatively difficult, it is possible to reduce the emission gas by lowering combustion temperature and making uniform combustion. Many premixed combustion is applied.

In the case of premixed combustion, in the fuel nozzle assembly 1230, the compressed air introduced from the compressor 1100 is mixed with the fuel and then enters the combustion chamber 1240. The initial ignition of the premixed gas is performed using an igniter, and then combustion is maintained by supplying fuel and air once the combustion is stable.

The fuel nozzle assembly 1230 includes a plurality of fuel nozzles 2000 for injecting fuel fluid, where the fuel nozzles 2000 allow the fuel to mix with the air at an appropriate ratio to achieve a state suitable for combustion. In the plurality of fuel nozzles 2000, a plurality of external fuel nozzles may be radially disposed about one internal fuel nozzle. The fuel nozzle 2000 will be described in detail later.

Combustion chamber assembly 1220 has a combustion chamber 1240, which is a space where combustion occurs, and includes a liner 1250 and a transition piece 1260.

The liner 1250 is disposed downstream of the fuel nozzle assembly 1230 and may be a dual structure of the inner liner 1251 and the outer liner 1252. That is, the inner liner 1251 may have a double structure in which the outer liner 1252 is surrounded. At this time, the inner liner 1251 is a tubular member having an empty interior, and the inner liner 1251 forms a combustion chamber 1240 therein. Compressed air may penetrate into the annular space inside the outer liner 1252 to cool the inner liner 1251.

On the other hand, the transition piece (1260) is located downstream of the liner 1250, the transition piece 1260 can send the combustion gas generated in the combustion chamber 1240 to the turbine 1300 at high speed. The transition piece 1260 may have a dual structure of an inner transition piece 1261 and an outer transition piece 1262. That is, the inner transition piece 1261 may be formed in a double structure surrounding the outer transition piece 1262. Similar to the inner liner 1251, the inner transition piece 1261 may be formed of a hollow tubular member, and may have a shape in which the diameter decreases gradually from the liner 1250 toward the turbine 1300. At this time, the inner liner 1251 and the inner transition piece 1261 may be coupled to each other by a plate spring seal (not shown). Since each end of the inner liner 1251 and the inner transition piece 1261 are fixed to the combustor 1200 and the turbine 1300 respectively, the plate spring seal is capable of accommodating elongation of the length and diameter due to thermal expansion. The inner liner 1251 and the inner transition piece 1261 may be supported.

The inner liner 1251 and the inner transition piece 1261 are structured to surround the outer liner 1252 and the outer transition piece 1262, and the annular space and the inner transition between the inner liner 1251 and the outer liner 1252 are made. Compressed air may penetrate into the environmental space between the piece 1261 and the outer transition piece 1262. Compressed air that penetrates the annular space can cool the inner liner 1251 and the inner transition piece 1261.

Meanwhile, the hot and high pressure combustion gas produced by the combustor 1200 is supplied to the turbine 1300 through the liner 1250 and the transition piece 1260. In the turbine 1300, while the combustion gas is adiabaticly expanded, the combustion gas collides with a plurality of blades disposed radially on the rotation axis of the turbine 1300 to give a reaction force, thereby converting thermal energy of the combustion gas into mechanical energy in which the rotation axis rotates. Part of the mechanical energy obtained from the turbine 1300 is supplied to the energy required to compress the air in the compressor, the remainder is used as the effective energy, such as driving the generator to produce power.

Hereinafter, a fuel nozzle according to an embodiment of the present invention will be described with reference to the drawings.

The fuel nozzle 2000 according to an embodiment of the present invention includes an injection cylinder 2100, a swirler 2200, an injector module 2300, a nozzle flange 2400, and a shroud 2500.

The injection cylinder 2100 is a means for supplying fuel and premixing fuel and air and extending in one direction. The injection cylinder 2100 may be generally formed in a cylindrical shape, but is not limited thereto. In the embodiment of the present invention, the injection cylinder 2100 is illustrated as an example.

A gas flow passage 2110 through which fuel gas flows may be formed in the injection cylinder 2100. The gas flow passage 2110 may communicate with the inside of the swirler 2200, and the fuel gas may be discharged through an outlet 2210 penetrating through the inside and outside of the swirler 2200 through the communicated flow passage inside the swirler 2200. . The discharged fuel gas is mixed with compressed air supplied from the compressor 1100.

In addition, a liquid flow passage 2120 through which liquid fuel flows may be formed in the injection cylinder 2100. The liquid passage 2120 may be formed to communicate with the injector module 2300 from the nozzle flange 2400. Secondary fuels such as distilled water, bio-diesel, ethanol, and the like may be flowed through the liquid flow path 2120.

In addition, the injection cylinder 2100 may be formed with an air inlet 2130 through which air is introduced into the discharge cylinder 2100 and an outlet 2120 through which air and fuel are mixed and discharged. The outlet 2120 may be formed at a downstream end of the injection cylinder 2100, and in this embodiment, the discharge port 2120 is formed on the bottom surface of the cylindrical injection cylinder 2100.

The shroud 2500 is formed to be spaced apart from the injection cylinder 2100 to longitudinally surround the injection cylinder 2100 to form a flow path for passing fuel and air. The shroud 2500 extends along the extending direction of the injection cylinder 2100. Preferably, the shroud 2500 has a concentric axis with the injection cylinder 2100 and is spaced apart from the injection cylinder 2100 at a predetermined interval to surround the injection cylinder 2100. Can be. In the embodiment of the present invention, a cylindrical shroud 2500 is illustrated. In this case, the cross section of the flow path formed by the injection cylinder 2100 and the shroud 2500 may be formed in an annular shape.

A swirler 2200 is radially arranged on the outer circumferential surface of the middle of the injection cylinder 2100, so that rotational flow occurs in the fuel fluid introduced into the space between the shroud 2500 and the injection cylinder 2100. The swirler 2200 may have a flow passage communicating therewith with the gas flow passage 2110 of the injection cylinder 2100.

4 is a cross-sectional view showing a fuel nozzle according to an embodiment of the present invention, Figure 5 is an enlarged cross-sectional view of the end of the fuel nozzle according to an embodiment of the present invention, Figures 6 and 7 of the present invention A cross-sectional view of an injector module in a fuel nozzle according to an embodiment.

Generally, a gas turbine premixes gas and supplies it to a combustion chamber. In addition, gas turbines are often provided with a liquid injector (hereinafter referred to as an 'injector') for injecting liquid fuel as secondary fuel or preliminary fuel. The injector preferably maintains hermetic sealing in the flow path where gas premixing is performed to ensure proper performance.

The fuel nozzle according to the embodiment of the present invention may maintain an airtight sealing in a high temperature environment at the time of use when in use, and includes an injector module 2300 that is easily detachable when the operation is stopped.

In the fuel nozzle according to the embodiment of the present invention, the injector module 2300 is inserted into the insertion site formed in the injection cylinder 2100, and may be made of a material having a thermal expansion rate different from that of the injection cylinder 2100. . When the thermal expansion rate of the material forming the injection cylinder 2100 is referred to as a first thermal expansion rate, the injector module 2300 may be formed of a material having a second thermal expansion rate different from the first thermal expansion rate. It is preferable to configure the injector module 2300 such that the thermal expansion rate of the injector module 2300 is greater than that of the injection cylinder 2100. Of course, on the contrary, the injector module 2300 may be configured such that the thermal expansion rate of the injection cylinder 2100 is greater than that of the injector module 2300.

In detail, the injector module 2300 is formed of a shape corresponding to the shape of the injector 2310 and the injector, and has a second thermal expansion rate different from the thermal expansion rate (first thermal expansion rate) of the material forming the injection cylinder 2100. It comprises a coupling portion 2320 made up. Here, the injector 2310 is a device for injecting liquid fuel, and may be various types of injectors, such as a spray liquid fuel injector, a jet injector, an orifice type injector, and the present invention is limited to the structure or principle of operation. Do not put

As shown in FIG. 6, the coupling part 2320 is inserted into the injection cylinder 2100 through an inner wall of the injection cylinder 2100, and an outer circumferential surface of the coupling part 2320 is formed in a thread shape. In this case, a thread shape corresponding to the thread of the coupling part 2320 is formed in the injection cylinder 2100. The inner circumferential surface of the coupling unit 2320 may be formed in a shape corresponding to the external shape of the injector 2310 so that the injector 2310 may be fitted into the coupling unit 2320.

Meanwhile, as illustrated in FIG. 7, the coupling part 2320 may be integrally formed with the injector 2310. That is, the coupling part 2320 may perform a housing function to form the appearance of the injector. At this time, the inside of the injector (2311) has a configuration for the injection of the liquid fuel, the housing of the injector is made of a material having a second thermal expansion rate different from the first thermal expansion rate and formed of a coupling portion 2320 having a thread shape Can be. At this time, although the 2nd thermal expansion rate may be formed smaller than 1st thermal expansion rate, it is preferable that 2nd thermal expansion rate is larger than 1st thermal expansion rate.

It describes the operation of the fuel nozzle according to an embodiment of the present invention configured as described above.

First, when designing the fuel nozzle 2000, the injector module 2300 is injected in a somewhat loose state by making the thread-shaped insertion site formed through the injection cylinder 2100 slightly larger than the width of the injector module 2300. To be inserted into the cylinder 2100. In this case, the thermal expansion rate of the injector module 2300 is greater than the thermal expansion rate of the injection cylinder 2100.

When using a gas turbine, as the temperature of the combustor 1200 rises, the injector module 2300 (specifically, the coupling part 2320) expands more of the injection cylinder 2100 and is continuously heated. Accordingly, the injector module 2300 expands to hermetically seal the insertion portion formed through the injection cylinder 2100.

When the gas turbine stops operating, the injector module 2300 shrinks faster than the injection cylinder 2100 as the temperature of the combustor 1200 decreases. Accordingly, the fastening state of the injector module 2300 and the injection cylinder 2100 becomes a loose state, and when the injector module 2300 is rotated in this state, the injector module 2300 can be easily detached.

When the thermal expansion rate of the injector module 2300 is smaller than the thermal expansion rate of the injection cylinder 2100, there is a difference that the injection cylinder 2100 expands and contracts quickly, and when the gas turbine is used, the injector module 2300 is airtight. It is the same point that it seals and becomes loose when gas turbine operation stops, and is easily removable. However, since the size of the injector module 2300 is relatively smaller than the size of the injection cylinder 2100, it is preferable that the thermal expansion rate of the injector module 2300 is greater than the thermal expansion rate of the injection cylinder 2100 to maintain manufacturing costs or equipment. It is advantageous in terms of.

The embodiments and drawings attached to this specification are merely to clearly show some of the technical ideas included in the present invention, and those skilled in the art can easily infer within the scope of the technical ideas included in the specification and drawings of the present invention. Various modifications and specific embodiments that can be made will be apparent to be included in the scope of the invention.

1100: compressor 1200: combustor
1210: burner module 1220: combustion chamber assembly
1230 fuel nozzle assembly 1300 turbine
2000: fuel nozzle 2100: injection cylinder
2200: swirler 2300: injector module
2310: injector 2320: coupling
2400: nozzle flange 2500: shroud

Claims (17)

An injection cylinder extending in one direction to supply fuel fluid to the combustion chamber;
A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder;
A swirler formed between the injection cylinder and the shroud; And
It is inserted into the insertion portion formed in the injection cylinder and comprises an injector module for injecting liquid fuel,
And the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.
The method of claim 1, wherein the injector module,
A fuel nozzle comprising an injector and a coupling portion formed of a material having a shape corresponding to an outer shape of the injector and having a second coefficient of thermal expansion.
The method of claim 2,
The outer circumferential surface of the coupling portion is formed in a thread shape, the inner circumferential surface of the coupling portion is formed in a shape corresponding to the external shape of the injector.
The method of claim 2,
The coupling part is a fuel nozzle formed integrally with the injector.
The method according to any one of claims 1 to 4,
And said second thermal expansion rate is greater than said first thermal expansion rate.
The method according to any one of claims 1 to 4,
A liquid passage through which liquid fuel flows is formed in the injection cylinder, and the liquid passage communicates with the injector module.
A combustion chamber assembly comprising a combustion chamber in which fuel fluid combusts;
A fuel nozzle assembly comprising a plurality of fuel nozzles for injecting the fuel fluid into the combustion chamber,
The fuel nozzle,
An injection cylinder extending in one direction to supply fuel fluid to the combustion chamber;
A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder;
A swirler formed between the injection cylinder and the shroud;
It is inserted into the insertion portion formed in the injection cylinder and comprises an injector module for injecting liquid fuel,
And the injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.
The method of claim 7, wherein the injector module,
A combustor comprising an injector and a coupling portion formed of a material having a shape corresponding to an outer shape of the injector and having a second coefficient of thermal expansion.
The method of claim 8,
The outer circumferential surface of the coupling portion is formed in a thread shape, the inner circumferential surface of the coupling portion is formed in a shape corresponding to the external shape of the injector.
The method of claim 8,
Combustor is formed integrally with the injector.
The method according to any one of claims 7 to 10,
And said second coefficient of thermal expansion is greater than said first coefficient of thermal expansion.
The method according to any one of claims 7 to 10,
And a liquid passage through which liquid fuel flows is formed in the injection cylinder, and the liquid passage communicates with the injector module.
A compressor for compressing incoming air;
A combustor for mixing and combusting the compressed air and fuel in the compressor; And
And a turbine generating power from the gas burned in the combustor.
The combustor,
A combustion chamber assembly comprising a combustion chamber in which fuel fluid combusts;
A fuel nozzle assembly comprising a plurality of fuel nozzles for injecting the fuel fluid into the combustion chamber,
The fuel nozzle,
An injection cylinder extending in one direction to supply fuel fluid to the combustion chamber;
A shroud formed spaced apart from the injection cylinder and surrounding the injection cylinder;
A swirler formed between the injection cylinder and the shroud;
It is inserted into the insertion portion formed in the injection cylinder and comprises an injector module for injecting liquid fuel,
The injection cylinder is made of a material having a first coefficient of thermal expansion, and the injector module is made of a material having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.
The method of claim 13, wherein the injector module,
A gas turbine comprising an injector and a coupling portion formed of a material having a shape corresponding to an outer shape of the injector and having a second coefficient of thermal expansion.
The method of claim 14,
The outer circumferential surface of the coupling portion is formed in a thread shape, the inner circumferential surface of the coupling portion is formed in a shape corresponding to the external shape of the injector.
The method of claim 14,
The coupling portion is a gas turbine formed integrally with the injector.
The method according to any one of claims 13 to 16,
And said second coefficient of thermal expansion is greater than said first coefficient of thermal expansion.

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