JP3861033B2 - Strut structure of gas turbine exhaust - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a strut structure for an exhaust section of a gas turbine.
[0002]
[Prior art]
In the gas turbine, the air sucked from the intake chamber is compressed by the rotation of the rotor in the compressor and is brought into a high-temperature and high-pressure state and led to the combustor. The air led to the combustor is mixed with the supplied fuel and burned to become high-temperature and high-pressure combustion gas. The combustion gas expands in the turbine section, and its energy is converted into the rotational force of the turbine. A part of the rotational force becomes the power of the compressor, and another part becomes the output of the gas turbine. The combustion gas after being converted into rotational force by the turbine section passes through the exhaust section and is discharged to the exhaust duct.
[0003]
As shown in FIG. 3, the exhaust portion 1 is formed in a cylindrical outer wall 3 formed in a cylindrical shape, a cylindrical outer diffuser 5 provided on the inner side of the inner wall 3, and an inner side of the outer diffuser 5. And a cylindrical inner diffuser 7 provided. The casing wall 3 is supported by a base plate (not shown), and a rotor bearing (not shown) is disposed on the inner peripheral side of the cylindrical inner diffuser 7. Accordingly, the casing wall 3, the outer diffuser 5, and the inner diffuser 7 each having a cylindrical shape are arranged concentrically so that an annular outer peripheral cavity is formed between the casing wall 3 and the outer diffuser 5. 9, and an annular combustion gas passage 11 is formed between the outer diffuser 5 and the inner diffuser 7.
[0004]
By the way, the inner diffuser 7 is supported on the vehicle interior wall 3 via struts (not shown). That is, the strut supports the inner diffuser 7 by fixing the outer end to the vehicle interior wall 3 and fixing the inner end penetrating the outer diffuser 5 to the outer periphery of the inner diffuser 7. The figure shows a tangential strut support, and the inner ends of the six struts are connected so as to contact the outer peripheral surface of the inner diffuser 7 in the tangential direction.
[0005]
Since the strut supports the inner diffuser 7 across the combustion gas passage 11, it is exposed to high-temperature combustion gas. Therefore, the strut is provided with a gap 13 shown in FIG. 4 between the outer surface and covered with a strut cover 15, and a part of the compressed air from the compressor is introduced into the gap 13 as cooling air to The rise is prevented and the occurrence of thermal expansion is suppressed. As shown in FIG. 5, the strut cover 15 is fixed to the outer end and the vehicle interior wall 3, the outer periphery of the central portion and the outer diffuser 5, and the inner end and the inner diffuser 7 by welding portions 17. That is, the strut cover 15 covers the struts, forms a flow path for cooling air, and further serves as a support member for the outer diffuser 5. Note that, unlike the illustrated example, the strut cover 15 may have a flare shape in which an outer end (base) that is a connection portion with the vehicle interior wall 3 is greatly bulged.
[0006]
[Problems to be solved by the invention]
However, the temperature of the exhaust gas flowing through the combustion gas passage is 600 ° C. or higher, whereas the temperature of the casing wall located on the opposite side of the combustion gas passage across the outer peripheral cavity is lower, so the temperature distribution of the strut cover is It becomes non-uniform. In addition, the temperature distribution differs between when the gas turbine starts and when it stops. That is, the temperature of the outer diffuser and the inner diffuser is high at startup and lower than that at stop. On the other hand, the temperature of the passenger compartment wall is low during startup and higher than that during stoppage. Accordingly, the strut cover is accompanied by thermal stress, and particularly the strut cover expands and contracts in the axial direction. However, the strut cover has an outer end and a casing wall, an outer periphery and outer diffuser at the center, and an inner end and an inner diffuser, which are fixed by welding. strut cover the base of the flared portion, etc.) stress is concentrated on the low-cycle (10 ⁴ times due to thermal stress) fatigue occurs. This low cycle fatigue also causes cracking. For this reason, repairs occur at every periodic inspection, which requires repair time and cost, and is also a factor that decreases the responsiveness.
The present invention has been made in view of the above situation, and provides a strut structure for a gas turbine exhaust part that does not generate cracks due to low-cycle fatigue due to thermal stress, thereby reducing repair time and cost and preventing deterioration of availability. It aims to plan.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a strut structure for a gas turbine exhaust part according to claim 1 of the present invention comprises a cylindrical casing wall, a cylindrical outer diffuser provided inside the casing wall, and an outer side. A cylindrical inner diffuser provided inside the diffuser, a strut whose outer end is fixed to the vehicle interior wall and the inner end penetrating the outer diffuser is fixed to the outer periphery of the inner diffuser, covers the strut, the outer end and the vehicle In the strut structure of the gas turbine exhaust section including the chamber wall, the outer periphery of the center portion and the outer diffuser, and the strut cover to which the inner end and the inner diffuser are fixed, the strut cover between the vehicle chamber wall and the outer diffuser Further, the present invention is characterized in that an expansion / contraction means that is extendable and contractible in the axial direction of the strut cover is provided.
[0008]
In this gas turbine exhaust strut structure, the strut cover between the casing wall and the outer diffuser is provided with expansion / contraction means that can be expanded and contracted in the axial direction of the strut cover. Even if the strut cover expands and contracts, the expansion and contraction is absorbed by the expansion and contraction means. As a result, the strut cover is not stretched and cracks due to low cycle fatigue due to thermal stress are not generated.
[0009]
The strut structure of the gas turbine exhaust part according to claim 2 is the strut structure of the gas turbine exhaust part according to claim 1, wherein the expansion and contraction means includes an inner end of the outer cover and an outer end of the inner cover. It is a slide structure part slidably fitted in the axial direction.
[0010]
In the strut structure of the gas turbine exhaust part, when the strut cover expands and contracts in the axial direction of the strut cover, the fitting part between the outer cover and the inner cover slides, and the increase / decrease length is absorbed. Accordingly, the strut cover is not stretched with a simple structure without using another member, and low cycle fatigue due to thermal stress is suppressed.
[0011]
The strut structure of the gas turbine exhaust part according to claim 3 is the strut structure of the gas turbine exhaust part according to claim 1, wherein the expansion / contraction means is interposed between the inner end of the outer cover and the outer end of the inner cover. It is a flexible structure member that can expand and contract in the axial direction of the strut cover .
[0012]
In the strut structure of the gas turbine exhaust section, when the strut cover expands and contracts in the axial direction of the strut cover , the flexible structure member expands and contracts and the length of the increase / decrease is absorbed. This eliminates the strut cover tension while ensuring the airtightness between the outer cover and the inner cover, and suppresses low cycle fatigue caused by thermal stress.
[0013]
The strut structure of the gas turbine exhaust part according to claim 4 is the strut structure of the gas turbine exhaust part according to claim 1, 2, or 3, wherein a spring member that supports the casing wall and the outer diffuser in a relatively displaceable manner is provided. It is provided over the compartment wall and the outer diffuser.
[0014]
In the strut structure of the gas turbine exhaust section, the spring member is provided across the vehicle compartment wall and the outer diffuser, so that the rigidity is sufficient to support the outer diffuser and the inner diffuser while securing the displacement absorbing action by the expansion and contraction means. Is applied to the stretchable member interposing part of the strut cover.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a strut structure of a gas turbine exhaust part according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is an enlarged cross-sectional view of a main part showing a strut structure of an exhaust part of a gas turbine according to the present invention.
[0016]
The exhaust part 21 includes an outer casing wall 23 formed in a cylindrical shape, a cylindrical outer diffuser 25 provided inside the casing wall 23, and a cylindrical inner side provided inside the outer diffuser 25. And a diffuser 27. The casing wall 23 is supported by a base plate (not shown), and a rotor bearing (not shown) is disposed on the inner peripheral side of the cylindrical inner diffuser 27. Accordingly, the casing wall 23, the outer diffuser 25, and the inner diffuser 27 each having a cylindrical shape are arranged concentrically, so that an annular outer peripheral cavity is formed between the casing wall 23 and the outer diffuser 25. 29, and an annular combustion gas passage 31 is formed between the outer diffuser 25 and the inner diffuser 27.
[0017]
The inner diffuser 27 is supported by the passenger compartment wall 23 via struts (not shown). That is, the strut supports the inner diffuser 27 by fixing the outer end to the vehicle interior wall 23 and fixing the inner end penetrating the outer diffuser 25 to the outer periphery of the inner diffuser 27.
[0018]
The strut is provided with a gap 33 between the outer surface and covered with a strut cover 35, and a part of the compressed air from the compressor is introduced into the gap 33 as cooling air to prevent temperature rise and thermal expansion. Is suppressed. In the strut cover 35, the outer end and the vehicle interior wall 23, the outer periphery of the central portion and the outer diffuser 25, and the inner end and the inner diffuser 27 are fixed by welding portions 36. That is, the strut cover 35 covers the strut, forms a cooling air flow path, and further serves as a support member for the outer diffuser 25.
[0019]
The strut cover 35 has expansion / contraction means that can expand and contract in the axial direction of the strut cover 35 between the compartment wall 23 and the outer diffuser 25. The strut cover 35 has an outer end 37 fixed to the vehicle interior wall 23 and an inner end opened between the vehicle interior wall 23 and the outer diffuser 25, and an inner end fixed to the inner diffuser 27. The inner cover 39 is fixed to the outer diffuser 25 and the outer end is slidably fitted to the inner end of the outer cover 37. In the present embodiment, the expansion / contraction means is a slide structure portion 35 a in which the inner end of the outer cover 37 and the outer end of the inner cover 39 are slidably fitted in the axial direction of the strut cover 35 . In the present embodiment, an example in which the inner peripheral side of the inner cover 39 is extrapolated to the outer peripheral side of the outer cover 37 is illustrated, but a reverse fitting structure may be employed.
[0020]
Further, in the vicinity of the strut cover 35, a spring member (plate spring) 40 that supports the casing wall 23 and the outer diffuser 25 so as to be relatively displaceable is provided across the casing wall 23 and the outer diffuser 25. . The leaf spring 40 is formed in a square shape, and one end thereof is fixed to the vehicle compartment wall 23 with the bent portion being the center, and the other end is fixed to the outer diffuser 25. In the present embodiment, a pair of leaf springs 40 are provided on the left and right with the strut cover 35 interposed therebetween. Thereby, uniform support rigidity can be provided on the left and right sides of the expansion and contraction means. Further, since FIG. 1 is a front view when the flow direction is viewed from the upstream side of the gas flow, the plate spring 40 has a plate surface extending in a direction parallel to the gas flow. That is, it is attached in a direction that does not increase the exhaust resistance.
[0021]
According to the strut structure of the gas turbine exhaust portion configured as described above, the strut cover 35 between the casing wall 23 and the outer diffuser 25 is provided with a slide structure portion 35 a that is extendable in the axial direction of the strut cover 35. Even if the strut cover 35 expands and contracts due to the non-uniform temperature distribution and its variation, the expansion and contraction is absorbed by the slide structure portion 35a. As a result, the strut cover 35 is not stretched and cracks due to low cycle fatigue caused by thermal stress are not generated.
[0022]
When the strut cover 35 expands and contracts in the axial direction of the strut cover 35, the fitting portion 35a of the outer cover 37 and the inner cover 39 slides, and the increase / decrease length is absorbed. Thus, the strut cover 35 is not stretched with a simple structure without using a separate member, and low cycle fatigue due to thermal stress is suppressed.
[0023]
Furthermore, in the strut structure of the gas turbine exhaust part, the leaf spring 40 is disposed between the vehicle compartment wall 23 and the outer cover 37, so that the outer diffuser 25, Rigidity sufficient to support the inner diffuser 27 can be imparted to the slide structure 35 a of the strut cover 35.
[0024]
Next, another embodiment according to the present invention will be described.
FIG. 2 is an enlarged cross-sectional view of a main part showing another embodiment. In addition, the same code | symbol is attached | subjected to the member same as the member shown in FIG. 1, and the overlapping description shall be abbreviate | omitted.
The strut structure of the gas turbine exhaust section according to the present embodiment is a flexible structure in which the expansion / contraction means can expand and contract in the axial direction of the strut cover 47 interposed between the inner end of the outer cover 41 and the outer end of the inner cover 43. Member 45 is formed. The flexible structure member 45 can be, for example, a bellows tube that can be expanded and contracted in the axial direction of the strut cover 47 and connects the inner end of the outer cover 41 and the outer end of the inner cover 43 so as to be close to and away from each other.
[0025]
In the strut structure of the gas turbine exhaust section, when the strut cover 47 expands and contracts in the axial direction of the strut cover 47 , the flexible structure member 45 expands and contracts, and the increase / decrease length is absorbed. Thereby, while ensuring the airtightness between the outer cover 41 and the inner cover 43, the strut cover 47 can be prevented from being stretched, and low cycle fatigue due to thermal stress can be suppressed.
[0026]
【The invention's effect】
As described above in detail, according to the strut structure of the gas turbine exhaust part according to claim 1 of the present invention, the strut cover between the casing wall and the outer diffuser can be extended and contracted in the axial direction of the strut cover. Since the expansion / contraction means is provided, even if the strut cover expands / contracts due to the non-uniform temperature distribution or its variation, the expansion / contraction can be absorbed by the expansion / contraction means. As a result, the strut cover is not stretched and cracks due to low cycle fatigue due to thermal stress are not generated. As a result, it is possible to reduce the repair time and repair cost and prevent the availability from being lowered.
[0027]
According to the strut structure of the gas turbine exhaust part according to claim 2, the telescopic means is a slide structure part in which the inner end of the outer cover and the outer end of the inner cover are slidably fitted in the axial direction of the strut cover. Therefore, when the strut cover expands and contracts in the axial direction of the strut cover, the fitting portion between the outer cover and the inner cover slides to absorb the increase / decrease length. Thereby, without using a separate member, the strut cover can be eliminated with a simple structure, and low cycle fatigue due to thermal stress can be suppressed.
[0028]
According to the strut structure of the gas turbine exhaust part according to claim 3, the flexible structure member is extendable in the axial direction of the strut cover interposed between the inner end of the outer cover and the outer end of the inner cover. Therefore, when the strut cover expands and contracts in the axial direction of the strut cover , the flexible structural member expands and contracts, and the increase / decrease length can be absorbed. Thereby, while ensuring airtightness between the outer cover and the inner cover, it is possible to eliminate the strut cover tension and suppress low cycle fatigue due to thermal stress.
[0029]
According to the strut structure of the gas turbine exhaust part according to claim 4, the spring member that supports the casing wall and the outer diffuser so as to be relatively displaceable is provided across the casing wall and the outer diffuser. The rigidity sufficient to support the outer diffuser and the inner diffuser can be imparted to the expansion / contraction means interposing part of the strut cover, while securing the displacement absorbing action by.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of a main part showing a strut structure of an exhaust section of a gas turbine according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part showing another embodiment.
FIG. 3 is a cross-sectional view orthogonal to the axial direction of the exhaust part in a conventional exhaust part.
FIG. 4 is an enlarged cross-sectional view of a main part in a conventional exhaust part.
FIG. 5 is an enlarged perspective view of a main part of a conventional exhaust part.
[Explanation of symbols]
21; exhaust part 23; vehicle compartment wall 25; outer diffuser 27; inner diffuser 35; strut cover 35a; slide structure part (expandable means)
37; outer cover 39; inner cover 40; leaf spring (spring member)
41; outer cover 43; inner cover 45; flexible structure member (expandable means)
47; Strut cover

Claims (4)

A cylindrical casing wall, a cylindrical outer diffuser provided inside the casing wall, a cylindrical inner diffuser provided inside the outer diffuser, and an outer diffuser whose outer end is fixed to the casing wall A strut whose inner end is fixed to the outer periphery of the inner diffuser, a strut cover that covers the strut, and the outer end and the vehicle interior wall, the outer periphery and the outer diffuser at the center, and the inner end and the inner diffuser are fixed to each other. In the strut structure of the gas turbine exhaust section equipped with
A strut structure for a gas turbine exhaust section, characterized in that a strut cover between a vehicle compartment wall and an outer diffuser is provided with expansion / contraction means that can expand and contract in the axial direction of the strut cover . In the strut structure of the gas turbine exhaust part according to claim 1,
The expansion / contraction means is
A strut structure for a gas turbine exhaust section, wherein the strut structure is a slide structure part in which an inner end of an outer cover and an outer end of an inner cover are slidably fitted in the axial direction of the strut cover . In the strut structure of the gas turbine exhaust part according to claim 1,
The expansion / contraction means is
A strut structure for an exhaust section of a gas turbine, wherein the strut structure is a flexible structure member that is extendable in an axial direction of the strut cover interposed between an inner end of the outer cover and an outer end of the inner cover. In the strut structure of the gas turbine exhaust part according to claim 1, 2 or 3,
A strut structure for an exhaust section of a gas turbine, wherein a spring member that supports a casing wall and an outer diffuser so as to be relatively displaceable is provided across the casing wall and the outer diffuser.

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