Intermediate shaft cover, and gas turbine equipped therewith

Abstract

This intermediate shaft cover comprises: a cylindrical inner cover covering an intermediate rotor shaft; an annular outer cover which covers an outer peripheral side of a diffuser space and which is connected to a gas turbine casing; and a strut which extends radially outward from an outer periphery of the inner cover, and which is connected directly or indirectly to the outer cover. The strut has a thick-walled portion and a thin-walled portion having a circumferential-direction thickness that is less than that of the thick-walled portion. The thick-walled portion is formed in a region of the strut including an outer connecting portion connected directly or indirectly to the outer cover. The thin-walled portion is formed in a region of the strut including an inner connecting portion connected to the inner cover.

Description

Technical Field

[0001] The present disclosure relates to an intermediate shaft cover and a gas turbine including the same. This application claims priority based on Japanese Patent Application No. 2022-160173 filed in Japan on October 4, 2022, and incorporates the content herein by reference.

Background Art

[0002] A gas turbine includes a compressor that compresses air, a combustor that burns fuel in the air compressed by the compressor to generate combustion gas, a turbine driven by the combustion gas, and an intermediate casing.

[0003] The compressor has a compressor rotor rotatable about an axis, a compressor casing covering the compressor rotor, and a diffuser. The compressor rotor has a compressor rotor shaft extending in the axial direction about the axis and a plurality of compressor blade rows provided on the compressor rotor shaft. The diffuser forms an annular diffuser space through which the air passing through the plurality of compressor blade rows passes. The diffuser has an outer diffuser defining an outer peripheral edge of the diffuser space and an inner diffuser defining an inner peripheral edge of the diffuser space. The turbine has a turbine rotor rotatable about an axis and a turbine casing covering the turbine rotor. The turbine rotor has a turbine rotor shaft extending in the axial direction about the axis and a plurality of turbine blade rows provided on the turbine rotor shaft.

[0004] The compressor rotor and turbine rotor are connected to each other to form a gas turbine rotor. In this gas turbine rotor, between multiple rows of compressor blades and multiple rows of turbine blades in the axial direction, there is an intermediate rotor shaft where no blade rows are provided. An intermediate casing is positioned between the compressor casing and the turbine casing, covering the intermediate rotor shaft. The compressor casing, intermediate casing, and turbine casing are connected to each other to form a gas turbine rotor. The combustor is attached to the intermediate casing.

[0005] The gas turbine described in Patent Document 1 below further includes an intermediate shaft cover. This intermediate rotor shaft has a cylindrical inner cover that covers the outer circumference of the intermediate rotor shaft, and a plurality of struts that extend radially from the outer circumference of the inner cover with respect to the axis. The plurality of struts are arranged in the circumferential direction with respect to the axis. The radially outer ends of the struts are connected to the axially downstream end of the outer diffuser.

[0006] The air discharged from the compressor's diffuser passes between multiple struts before flowing into the combustor. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2018 / 181902 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the field of gas turbines equipped with intermediate shaft covers, there is a demand to increase the strength of the connection points between the multiple struts and the outer diffuser. On the other hand, in this field, there is also a demand to reduce resistance during the process of air being discharged from the compressor diffuser and passing between the multiple struts.

[0009] Therefore, the present disclosure aims to provide an intermediate shaft cover that can increase the strength of the strut while suppressing resistance to the airflow from the compressor, and a gas turbine equipped with the same. [Means for solving the problem]

[0010] An intermediate shaft cover, as one embodiment for achieving the aforementioned objective, is applied to the following gas turbines. This gas turbine comprises a gas turbine rotor rotatable about an axis and a gas turbine casing covering the outer circumference of the gas turbine rotor. The gas turbine rotor has a gas turbine rotor shaft extending in the axial direction, a plurality of compressor blade rows provided on the upstream side of the gas turbine rotor shaft, and a plurality of turbine blade rows provided on the downstream side of the gas turbine rotor shaft, spaced downstream from the plurality of compressor blade rows. The intermediate shaft cover comprises a diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, forming an annular diffuser space centered on the axis; a cylindrical inner cover that covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows in the gas turbine rotor shaft, downstream of the diffuser from the axis; an annular outer cover that covers the outer circumference of the diffuser space and is connected to the gas turbine casing; and a strut that extends radially outward from the outer circumference of the inner cover with respect to the axis and is directly or indirectly connected to the outer cover. The strut has a thick-walled portion with a greater circumferential thickness with respect to the axis and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The thick-walled portion is formed in a region of the strut that includes an outer connecting portion that is directly or indirectly connected to the outer cover, including the radially outer end. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. The diffuser comprises an outer diffuser defining the outer edge of the diffuser space and an inner diffuser defining the inner edge of the diffuser space. The outer diffuser is formed such that its inner diameter gradually increases toward the downstream side of the axis. In the strut, the portion of the inner surface of the outer diffuser radially outside the extension of the generatrix that intersects with the virtual plane containing the axis includes the thickened portion. Another embodiment of an intermediate shaft cover for achieving the aforementioned objective is applied to the following gas turbines. This gas turbine comprises a gas turbine rotor rotatable about an axis and a gas turbine casing covering the outer circumference of the gas turbine rotor. The gas turbine rotor has a gas turbine rotor shaft extending in the axial direction, a plurality of compressor blade rows provided on the upstream side of the gas turbine rotor shaft, and a plurality of turbine blade rows provided on the downstream side of the gas turbine rotor shaft, spaced downstream from the plurality of compressor blade rows. The intermediate shaft cover comprises a diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, forming an annular diffuser space centered on the axis; a cylindrical inner cover that covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows in the gas turbine rotor shaft, downstream of the diffuser on the axis; an annular outer cover that covers the outer circumference of the diffuser space and is connected to the gas turbine casing; and a strut that extends radially outward from the outer circumference of the inner cover with respect to the axis and is directly or indirectly connected to the outer cover. The strut has a thick-walled portion with a greater circumferential thickness with respect to the axis and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The thick-walled portion includes an outer connecting portion in the strut that includes the radially outer end and is directly or indirectly connected to the outer cover, and is formed in a region radially outward from the diffuser space. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. In the strut, the circumferential thickness in the portion radially inward from the thick-walled portion is thinner than the circumferential thickness in the thick-walled portion. An intermediate shaft cover, as yet another embodiment for achieving the aforementioned objective, is applied to the following gas turbines. This gas turbine comprises a gas turbine rotor rotatable about an axis and a gas turbine casing covering the outer circumference of the gas turbine rotor. The gas turbine rotor has a gas turbine rotor shaft extending in the axial direction, a plurality of compressor blade rows provided on the upstream side of the gas turbine rotor shaft, and a plurality of turbine blade rows provided on the downstream side of the gas turbine rotor shaft, spaced downstream from the plurality of compressor blade rows. The intermediate shaft cover comprises a diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, forming an annular diffuser space centered on the axis; a cylindrical inner cover that covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows in the gas turbine rotor shaft, downstream of the diffuser from the axis; an annular outer cover that covers the outer circumference of the diffuser space and is connected to the gas turbine casing; and a strut that extends radially outward from the outer circumference of the inner cover with respect to the axis and is directly or indirectly connected to the outer cover. The strut has a thick-walled portion with a greater circumferential thickness with respect to the axis and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The thick-walled portion is formed in a region of the strut that includes an outer connecting portion that is directly or indirectly connected to the outer cover, including the radially outer end. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. The diffuser has an outer diffuser that defines the outer edge of the diffuser space and an inner diffuser that defines the inner edge of the diffuser space. The outer diffuser is formed such that its inner diameter gradually increases towards the downstream side of the axis. In the strut, the portion of the inner surface of the outer diffuser radially inward from the extension of the generatrix that intersects with a virtual plane containing the axis is the thin-walled portion.

[0011] In this embodiment, a thin layer is applied to the region of the strut that includes an outer connection portion that is directly or indirectly connected to the outer cover. From the meat department A thick-walled portion with greater circumferential thickness is formed. This increases the strength of the outer connection portion of the strut. Moreover, in this embodiment, a thin-walled portion with less circumferential thickness than the thick-walled portion is formed in the region of the strut that includes the inner connection portion connected to the inner cover. This prevents the narrowing of the flow path of compressed air discharged from the diffuser and passing alongside the strut. Therefore, in this embodiment, resistance during the process of compressed air passing alongside the strut can be reduced.

[0012] A gas turbine as one embodiment for achieving the aforementioned objective is: The gas turbine comprises an intermediate shaft cover as described above, a gas turbine rotor, a gas turbine casing, and a combustor attached to the gas turbine casing, which burns fuel in compressed air that has passed through the diffuser space to generate combustion gas. The combustor is configured such that the combustion gas is guided to the plurality of turbine blade rows. [Effects of the Invention]

[0013] In one aspect of this disclosure, the strength of the strut can be increased while reducing resistance to the airflow from the compressor. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a gas turbine system in one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the main part of a gas turbine around the intermediate shaft cover in the first embodiment of the present disclosure. [Figure 3] A cross-sectional view of a main part of an intermediate shaft cover in a first embodiment according to the present disclosure. [Figure 4] An exploded view showing a state where the intermediate shaft cover in the first embodiment according to the present disclosure is developed in the circumferential direction and viewed from the radially outer side. [Figure 5] A cross-sectional view taken along the line V-V in FIG. 4. [Figure 6] A cross-sectional view of a main part of a gas turbine around an intermediate shaft cover in a second embodiment according to the present disclosure. [Figure 7] A cross-sectional view of a main part of a gas turbine around an intermediate shaft cover in a third embodiment according to the present disclosure. [Figure 8] A cross-sectional view of a main part of a gas turbine around an intermediate shaft cover in a fourth embodiment according to the present disclosure

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of a gas turbine facility including an intermediate shaft cover according to the present invention, and various embodiments of the intermediate shaft cover will be described with reference to the drawings.

[0016] 「Embodiments of Gas Turbine Facilities」 Hereinafter, embodiments of a gas turbine facility will be described with reference to FIG. 1.

[0017] As shown in FIG. 1, the gas turbine facility of the present embodiment includes a gas turbine 10 and a cooling air supply device 1 that sends cooling air Acl to a part of the components of the gas turbine 10.

[0018] The gas turbine 10 includes a compressor 20 that compresses air A to generate compressed air Acom, a plurality of combustors 30 that burn fuel F in the compressed air Acom to generate combustion gas G, a turbine 40 driven by the high-temperature and high-pressure combustion gas G, an exhaust casing 16 through which exhaust gas EG, which is the combustion gas G exhausted from the turbine 40, flows, an intermediate casing 15, and an intermediate shaft cover 50.

[0019] The compressor 20 includes a compressor rotor 21 rotatable about axis Ar, a compressor casing 24 covering the compressor rotor 21, a plurality of compressor stator blade rows 25, and a diffuser 26. The turbine 40 includes a turbine rotor 41 rotatable about axis Ar, a turbine casing 44 covering the turbine rotor 41, and a plurality of turbine stator blade rows 45. In the following, the direction in which axis Ar extends will be called the axial direction Da, the circumferential direction around axis Ar will be simply called the circumferential direction Dc, and the direction perpendicular to axis Ar will be called the radial direction Dr. Also, one side of the axial direction Da will be called the upstream side Dau, and the opposite side will be called the downstream side Dad. Also, the side of the radial direction Dr that approaches axis Ar will be called the inner radial direction Dri, and the opposite side will be called the outer radial direction Dr.

[0020] The compressor 20 is positioned upstream of the turbine 40, on the axis Dau. The exhaust casing 16 is positioned downstream of the turbine 40, on the axis Dad.

[0021] The compressor rotor 21 has a compressor rotor shaft 22 extending in the axial direction Da with respect to the axis Ar, and a plurality of compressor rotor blade rows 23 attached to the compressor rotor shaft 22. The plurality of compressor rotor blade rows 23 are arranged in the axial direction Da. Each compressor rotor blade row 23 is composed of a plurality of rotor blades arranged in the circumferential direction Dc. One of a plurality of compressor stator blade rows 25 is positioned at the downstream Da of each of the plurality of compressor rotor blade rows 23 along the axis. Each compressor stator blade row 25 is located inside the compressor casing 24. Each compressor stator blade row 25 is composed of a plurality of stator blades arranged in the circumferential direction Dc.

[0022] The diffuser 26 forms a diffuser space S through which the air that has passed through multiple rows of compressor blades 23 passes. This diffuser space S is an annular space centered on the axis Ar.

[0023] The turbine rotor 41 has a turbine rotor shaft 42 extending in the axial direction Da with respect to the axis Ar, and a plurality of turbine rotor blade rows 43 attached to the turbine rotor shaft 42. The plurality of turbine rotor blade rows 43 are arranged in the axial direction Da. Each turbine rotor blade row 43 is composed of a plurality of rotor blades arranged in the circumferential direction Dc. One of a plurality of turbine stator blade rows 45 is located on the upstream side Dau of each of the plurality of turbine rotor blade rows 43. Each turbine stator blade row 45 is located inside the turbine casing 44. Each turbine stator blade row 45 is composed of a plurality of stator blades arranged in the circumferential direction Dc. The annular space on the outer circumference side of the turbine rotor shaft 42 and the inner circumference side of the turbine casing 44 forms a combustion gas flow path 49 through which the combustion gas G flows. The plurality of turbine stator blade rows 45 and the plurality of turbine rotor blade rows 43 are arranged in this combustion gas flow path 49.

[0024] The compressor rotor 21 and the turbine rotor 41 are located on the same axis Ar and are connected to each other to form a gas turbine rotor 11. Therefore, this gas turbine rotor 11 has a gas turbine rotor shaft 12 extending in the axial direction Da with axis Ar as the center, a plurality of compressor blade rows 23, and a plurality of turbine blade rows 43. Within the gas turbine rotor shaft 12, the space between the plurality of compressor blade rows 23 and the plurality of turbine blade rows 43 forms an intermediate rotor shaft 12m. For example, the rotor of a generator 9 is connected to this gas turbine rotor 11. The intermediate casing 15 is positioned in the axial direction Da between the compressor casing 24 and the turbine casing 44 and covers the intermediate rotor shaft 12m. Compressed air Acom discharged from the diffuser 26 of the compressor 20 flows into this intermediate casing 15. The compressor casing 24, the intermediate casing 15, the turbine casing 44, and the exhaust casing 16 are connected to each other to form a gas turbine casing 14.

[0025] The intermediate shaft cover 50 is positioned inside the intermediate casing 15 and covers the outer circumference of the intermediate rotor shaft 12m.

[0026] Multiple combustors 30 are mounted on the intermediate casing 15, aligned in the circumferential direction Dc. Each combustor 30 has a combustion chamber (or tail chamber) 32 that sends high-temperature, high-pressure combustion gas G to the combustion gas passage 49 of the turbine 40, and multiple burners 31 that inject fuel F together with compressed air Acom into the combustion chamber 32. The combustion chamber 32 is formed to allow the combustion gas G to be sent into the combustion gas passage 49 of the turbine 40.

[0027] The cooling air supply device 1 includes an extraction line 2 for extracting compressed air Acom from within the intermediate casing 15, a cooler 3 for cooling the compressed air Acom that has flowed through the extraction line 2, a cooling air line 4 for guiding the cooled compressed air Acom, or cooling air ACL, which has been cooled by the cooler 3, to the turbine rotor shaft 42, and a boost compressor 5 for compressing the cooling air ACL flowing through the cooling air line 4.

[0028] The compressor 20 draws in external air A and compresses it to produce compressed air Acom. This compressed air Acom is discharged from the diffuser 26 of the compressor 20 into the intermediate casing 15. The compressed air Acom in the intermediate casing 15 flows into the combustor 30. The burner 31 of the combustor 30 injects the compressed air Acom together with the fuel F supplied from the outside into the combustion chamber 32. Inside the combustion chamber 32, the fuel F burns in the compressed air Acom to become combustion gas G. This combustion gas G is sent to the combustion gas passage 49 of the turbine 40, which rotates the turbine rotor 41.

[0029] "First embodiment of an intermediate shaft cover" A first embodiment of the intermediate shaft cover will be described with reference to Figures 2 to 5.

[0030] As shown in Figure 2, the intermediate shaft cover 50 in this embodiment comprises a diffuser 26, an inner cover 61, a flange 52, a plurality of struts 53, and a passage cover 59 provided for each of the plurality of struts 53.

[0031] The diffuser 26 is the diffuser 26 of the compressor 20 mentioned above. Therefore, the diffuser 26 is a component of the compressor 20 and also a component of the intermediate shaft cover 50. As shown in Figures 3 to 5, the diffuser 26 has an outer diffuser 27 that defines the outer edge of the annular diffuser space S mentioned above, and an inner diffuser 28 that defines the inner edge of the diffuser space S. Figure 3 is a cross-sectional view of the main part of the intermediate shaft cover 50. Figure 4 is an unfolded view showing the intermediate shaft cover 50 unfolded in the circumferential direction Dc and viewed from the radially outer direction Dro. Figure 5 is a cross-sectional view of the VV line in Figure 4.

[0032] The inner diffuser 28 is cylindrical with the axis Ar as its center.

[0033] The outer diffuser 27 is an outer cover for the inner cover 61. This outer diffuser 27 has a cylindrical outer diffuser body 27m centered on the axis Ar, and a cooling air jacket 27j provided on the outer circumference of the outer diffuser body 27m in the portion downstream of the axis Dad. The outer diffuser body 27m defines the outer edge of the annular diffuser space S. The outer diffuser body 27m is formed so that its inner diameter gradually increases towards the downstream of the axis Dad. The end of the outer diffuser 27 on the upstream side Dau is attached to the gas turbine casing 14. The cooling air jacket 27j is annular centered on the axis Ar. This cooling air jacket 27j, in cooperation with the outer diffuser body 27m, forms an annular outer space P1 in the portion downstream of the axis Dad and on the outer circumference of the outer diffuser body 27m. The cooling air jacket 27j is connected to the cooling air line 4 of the cooling air supply device 1. Cooling air ACL from the cooling air line 4 can flow into the outer space P1 inside the cooling air jacket 27j.

[0034] The flange 52 forms an annular shape with respect to the axis Ar and is connected to the annular cooling air jacket 27j with respect to the axis Ar. This flange 52 is located on the outer circumference of the diffuser space S at the downstream end Da of the outer diffuser 27.

[0035] The inner cover 61 is located downstream of the diffuser 26 in the Dad region and upstream of the multiple turbine blade rows 43 in the Dau region, radially inward from the diffuser 26 in the Dri region. This inner cover 61 is cylindrical with the axis Ar as its center and covers the intermediate rotor shaft 12m. The inner cover 61 has a cylindrical inner first cover 62 with the axis Ar as its center and a cylindrical inner second cover 63 with the axis Ar as its center. The axial upstream end of the inner first cover 62 in the Dau region is connected to the axial downstream end of the inner diffuser 28 in the Dad region. The inner second cover 63 is located radially inward from the inner first cover 62 in the Dri region and is radially outward from the intermediate rotor shaft 12m in the axial direction. Extends to Da It forms an annular inner passage P4.

[0036] Multiple struts 53 are arranged in the circumferential direction Dc. Each strut 53 extends radially outward from the outer circumference of the inner first cover 62 to the flange 52. Thus, the multiple struts 53 are indirectly connected to the outer diffuser 27, which acts as an outer cover, via the flange 52.

[0037] Each strut 53 has a thickened portion 55, a thinned portion 57, and a portion with gradually changing thickness 56. In Figure 3, the strut 53 has a grid pattern, and the thickened portion 55 has a striped pattern. The partIn the thickness-gradual-change section 56, the unpatterned portion is the thin-walled section 57. The thick section 55 is formed in the strut 53 in a region that includes the outer connecting section 54o, which includes the radially outer end of Dro and is indirectly connected to the outer diffuser 27 as an outer cover. The thin-walled section 57 is formed in the strut 53 in a region that includes the inner connecting section 54i, which includes the radially inner end of Dri and is connected to the inner cover 61. The circumferential Dc thickness of this thin-walled section 57 is thinner than the circumferential Dc thickness of the thick section 55. The thickness-gradual-change section 56 is formed in the strut 53 between the thick section 55 and the thin-walled section 57. The circumferential Dc thickness of this thickness-gradual-change section 56 gradually decreases from the thick section 55 towards the thin-walled section 57. The thickness of this gradually changing thickness section 56 is the same as the thickness of the thick section 55 at the boundary between this gradually changing thickness section 56 and the thick section 55, and the thickness of this gradually changing thickness section 56 is the same as the thickness of the thin section 57 at the boundary between this gradually changing thickness section 56 and the thin section 57.

[0038] In the strut 53, the portion radially inward Dri from the extension line L (see Figure 3) of the generatrix that intersects the virtual plane containing the axis Ar on the inner circumferential surface of the outer diffuser 27 is a thin-walled portion 57. In other words, in the strut 53, the portion radially outward Dro from this extension line L is a portion with gradually changing thickness 56 and a thick portion 55.

[0039] The intermediate shaft cover 50 has a cooling air passage P that allows cooling air ACL from the cooling air line 4 of the cooling air supply device 1 to be sent to the turbine rotor shaft 42. The outer space P1 of the outer diffuser 27 mentioned above is part of this cooling air passage P.

[0040] Each strut 53 has a strut space 58 formed within it. This strut space 58 communicates with the outer space P1 via a connecting passage P2, which is part of the cooling air passage P. This strut space 58 extends from the connection surface of the strut 53 with the flange 52 to the inner circumferential surface of the inner first cover 62. The connecting passage P2 is formed in the cooling air jacket 27j and flange 52 of the outer diffuser 27.

[0041] Within the strut space 58, a passage cover 59 is positioned to define the strut passage P3, which is part of the cooling air passage P. This passage cover 59 is not positioned within the connecting passage P2. One end of the strut passage P3 communicates with the connecting passage P2. The other end of the strut passage P3 communicates with the inner passage P4 of the inner cover 61. In other words, the outer space P1, connecting passage P2, strut passage P3, and inner passage P4 described above communicate with each other to form a cooling air passage P that can send cooling air ACL from outside the gas turbine casing 14 to the turbine rotor shaft 42.

[0042] As shown in Figure 2, the turbine rotor shaft 42 has a cooling air passage 42p that communicates with the cooling air passage P of the intermediate shaft cover 50. Of the multiple turbine blade rows 43 attached to the turbine rotor shaft 42, the multiple blades 43b that make up the turbine blade row 43 furthest upstream on the axis Dau have cooling air passages 43p that communicate with the cooling air passage 42p of the turbine rotor shaft 42. Cooling air ACL from the cooling air passage P of the intermediate shaft cover 50 is sent to the cooling air passage 43p of the blades 43b via the cooling air passage 42p of the turbine rotor shaft 42. The cooling air ACL cools the blades 43b as it passes through the cooling air passage 43p of the blades 43b. This cooling air ACL flows out into the combustion gas flow path 49 from the outer surface of the blades 43b.

[0043] In this embodiment, a thickened portion 55 is formed in the strut 53 in a region including the outer connection portion 54o, which is indirectly connected to the outer diffuser 27, which is the outer cover, and the circumferential Dc thickness is greater than that of the thinned portion 57. Therefore, the strength of the outer connection portion 54o in the strut 53 can be increased. Moreover, in this embodiment, a thinned portion 57 is formed in the strut 53 in a region including the inner connection portion 54i, which is connected to the inner cover 61, and the circumferential Dc thickness is less than that of the thickened portion 55. Therefore, the narrowing of the flow path of compressed air Acom discharged from the diffuser 26 and passing alongside the strut 53 can be suppressed. Therefore, in this embodiment, resistance during the process of compressed air Acom passing alongside the strut 53 can be suppressed.

[0044] Most of the compressed air Acom discharged from the diffuser 26 and passing alongside the strut 53 passes through a radially inward Dri beyond the extension line L of the generatrix on the inner circumferential surface of the outer diffuser 27. In this embodiment, within the strut 53, the radially inward Dri beyond this extension line L is a thin-walled portion 57, and the radially outward Dro beyond this extension line L is a portion with gradually changing thickness 56 and a portion with a thicker wall 55. Therefore, in this embodiment, resistance during the process of compressed air Acom passing alongside the strut 53 can be reduced compared to when part of the gradually changing thickness portion 56 or part of the thicker wall 55 is located radially inward Dri beyond this extension line L.

[0045] In this embodiment, since a thickness variation section 56 exists between the thick section 55 and the thin section 57, stress concentration between the thick section 55 and the thin section 57 can be suppressed.

[0046] In this embodiment, the cooling air passage P, which consists of an outer space P1, a connecting passage P2, a strut passage P3, and an inner passage P4, can deliver cooling air ACL from outside the gas turbine casing 14 to the turbine rotor shaft 42. Furthermore, in this embodiment, the passage cover 59 in the strut space 58 is not located in the connecting passage P2, which is part of the cooling air passage P. Therefore, in this embodiment, the area around the connecting passage P2 can be directly cooled by the cooling air ACL flowing through the connecting passage P2. Thus, in this embodiment, the outer connection portion 54o of the strut 53 can be efficiently cooled, and the decrease in strength due to high temperature of the outer connection portion 54o of the strut 53 can be suppressed.

[0047] "Second embodiment of the intermediate shaft cover" A second embodiment of the intermediate shaft cover will be described with reference to Figure 6.

[0048] The intermediate shaft cover 50a in this embodiment is a modified version of the intermediate shaft cover 50 in the first embodiment. Similar to the intermediate shaft cover 50 in the first embodiment, the intermediate shaft cover 50a in this embodiment comprises a diffuser 26a, an inner cover 61, a plurality of struts 53, a passage cover 59 provided for each of the struts 53, and a flange 52. The intermediate shaft cover 50a in this embodiment further has an outer cover 51.

[0049] The outer cover 51 has a cylindrical outer cover body 51m centered on the axis Ar, and a cooling air jacket 51j provided on the outer circumference of the outer cover body 51m, on the downstream side Dad of the axis. The annular outer cover body 51m covers the outer circumference of the diffuser 26a. The upstream end Dau of this outer cover 51 is attached to the gas turbine casing 14. The cooling air jacket 51j is annular centered on the axis Ar. This cooling air jacket 51j, together with the outer cover body 51m, forms an annular outer space P1 on the outer circumference of the outer cover body 51m, on the downstream side Dad of the axis. The cooling air line 4 of the cooling air supply device 1 is connected to the cooling air jacket 51j. Cooling air ACL can flow into the outer space P1 within the cooling air jacket 51j from the cooling air line 4.

[0050] The diffuser 26a in this embodiment is the same as the diffuser in the first embodiment. 26 and Similarly, it has an outer diffuser 27a and an inner diffuser 28. The inner diffuser 28 in this embodiment is the same as the inner diffuser 28 in the first embodiment. On the other hand, the outer diffuser 27a in this embodiment is different from the outer diffuser 27 in the first embodiment. As mentioned above, the outer cover 51 has a cooling air jacket 51j that forms the outer space P1. For this reason, the outer diffuser 27a in this embodiment does not have the cooling air jacket 27j of the outer diffuser 27 in the first embodiment. The downstream Dad end of the outer diffuser 27a in this embodiment is in contact with or close to the downstream Dad end of the outer cover 51 in the radial direction Dr.

[0051] In this embodiment, the flange 52 is annular in shape with respect to the axis Ar, similar to the flange 52 in the first embodiment, and is connected to the annular cooling air jacket 51j with respect to the axis Ar. However, in this embodiment, the flange 52 is connected to the cooling air jacket 51j of the outer cover 51.

[0052] The inner cover 61 in this embodiment has the same configuration as the inner cover 61 in the first embodiment and covers the outer circumference of the intermediate rotor shaft 12m. Therefore, the inner cover 61 in this embodiment, like the inner cover 61 in the first embodiment, has a cylindrical inner first cover 62 centered on the axis Ar and a cylindrical inner second cover 63 centered on the axis Ar. The upstream end Dau of the inner first cover 62 is connected to the downstream end Dad of the inner diffuser 28. The inner second cover 63 is positioned radially inward Dri of the inner first cover 62 and connected to the inner first cover 62. The inner second cover 63, together with the inner first cover 62, is positioned radially inward Dri of the inner first cover 62 and radially outward Dro of the intermediate rotor shaft 12m, axially Extends to Da It forms an annular inner passage P4.

[0053] The multiple struts 53 in this embodiment are arranged in the circumferential direction Dc, in the same configuration as the multiple struts 53 in the first embodiment. Therefore, each strut 53 in this embodiment extends radially outward from the outer circumference of the inner first cover 62 to the flange 52. Thus, the multiple struts 53 are indirectly connected to the outer cover 51 via the flange 52.

[0054] Each strut 53 in this embodiment, although not explicitly shown in Figure 6, has a thick portion, a thin portion, and a portion with gradually changing thickness, similar to each strut 53 in the first embodiment. In the strut 53 of this embodiment, the portion Dri radially inward from the extension line L of the generatrix that intersects the virtual plane containing the axis Ar on the inner circumferential surface of the outer diffuser 27a is a thin portion 57, similar to the strut 53 in the first embodiment.

[0055] Similar to the first embodiment, each strut 53 has a strut space 58 formed within it. This strut space 58 communicates with the outer space P1 of the outer cover 51 via a connecting passage P2, which is part of the cooling air passage P. The connecting passage P2 is formed in the cooling air jacket 51j and flange 52 of the outer cover 51.

[0056] Similar to the first embodiment, a passage cover 59 is arranged within the strut space 58, defining the strut passage P3, which is part of the cooling air passage P. This passage cover 59 is not located within the connecting passage P2. The outer space P1, connecting passage P2, strut passage P3, and inner passage P4 are in communication with each other, forming a cooling air passage P that can send cooling air ACL from outside the gas turbine casing 14 to the turbine rotor shaft 42.

[0057] As described above, in this embodiment as well, similar to the first embodiment, a thin layer of material is applied to the region of the strut 53 that includes the outer connection portion indirectly connected to the outer cover 51. From the meat department Since a thick-walled portion with a greater circumferential thickness Dc is formed, the strength of the outer connection portion of the strut 53 can be increased. Furthermore, in this embodiment as well, in the region of the strut 53 that includes the inner connection portion connected to the inner cover 61, a thin-walled portion with a thinner circumferential thickness Dc than the thick-walled portion is formed, so that resistance can be reduced as the compressed air Acom is discharged from the diffuser 26a and passes alongside the strut 53.

[0058] As described above, unlike the first embodiment, the outer cover 51 may be a separate component from the outer diffuser 27a.

[0059] "Third embodiment of the intermediate shaft cover" A third embodiment of the intermediate shaft cover will be described with reference to Figure 7.

[0060] The intermediate shaft cover 50b in this embodiment is a modified version of the intermediate shaft cover 50a in the second embodiment. Similar to the intermediate shaft cover 50a in the second embodiment, the intermediate shaft cover 50b in this embodiment comprises a diffuser 26a, an outer cover 51b, an inner cover 61, a plurality of struts 53b, and a flange 52.

[0061] The outer cover 51b in this embodiment is cylindrical with respect to the axis Ar, similar to the outer cover 51 in the second embodiment. However, the outer cover 51b in this embodiment does not have the cooling air jacket 51j of the outer cover 51 in the second embodiment.

[0062] The diffuser 26a in this embodiment has an outer diffuser 27a and an inner diffuser 28, similar to the diffuser 26a in the second embodiment. In this embodiment, the downstream Dad end of the outer diffuser 27a is in contact with or close in radial direction Dr to the downstream Dad end of the outer cover 51b.

[0063] The flange 52 in this embodiment, like the flange 52 in the second embodiment, is annular in shape with respect to the axis Ar. This flange 52 is connected to the downstream end of the outer cover 51b on the axis Dad side.

[0064] The inner cover 61 in this embodiment has the same configuration as the inner cover 61 in the first embodiment and covers the outer circumference of the intermediate rotor shaft 12m. Therefore, the inner cover 61 in this embodiment, like the inner cover 61 in the second embodiment, has a cylindrical inner first cover 62 centered on the axis Ar and a cylindrical inner second cover 63 centered on the axis Ar. The upstream end Dau of the inner first cover 62 is connected to the downstream end Dad of the inner diffuser 28. The inner second cover 63 is positioned radially inward Dri of the inner first cover 62 and connected to the inner first cover 62. The inner second cover 63, together with the inner first cover 62, is radially inward Dri of the inner first cover 62 and radially outward Dro of the intermediate rotor shaft 12m, axially Extends to Da It forms an annular inner passage P4.

[0065] In this embodiment, the multiple struts 53b are arranged in the circumferential direction Dc, similar to the multiple struts 53 in the second embodiment. Therefore, each strut 53b in this embodiment extends radially outward from the outer circumference of the inner first cover 62 to the flange 52. Thus, the multiple struts 53b are indirectly connected to the outer cover 51b via the flange 52.

[0066] Each strut 53b in this embodiment, although not explicitly shown in Figure 7, has a thick portion, a thin portion, and a portion with gradually changing thickness, similar to each strut 53 in the first embodiment. In the strut 53b of this embodiment, the portion Dri radially inward from the extension line L of the generatrix that intersects the virtual plane containing the axis Ar on the inner circumferential surface of the outer diffuser 27a is a thin portion, similar to the strut 53 in the first embodiment.

[0067] Unlike the struts 53 in the above embodiments, the strut 53b in this embodiment does not have a strut space 58. Therefore, the intermediate shaft cover 50b in this embodiment does not have the passage cover 59 in the first and second embodiments.

[0068] The cooling air line 4b of the cooling air supply device 1 is connected to the inner first cover 62. Therefore, in this embodiment, the cooling air ACL from the cooling air supply device 1 can flow into the inner passage P4 of the inner cover 61 without passing through the outer cover 51b and struts 53, 53b. In other words, the cooling air passage Pb of the intermediate shaft cover 50b in this embodiment consists only of the inner passage P4 of the inner cover 61.

[0069] As described above, in this embodiment as well as in the first and second embodiments, a thin layer of material is applied to the region of the strut 53b that includes the outer connection portion indirectly connected to the outer cover 51b. From the meat departmentSince a thick-walled portion with a greater circumferential thickness Dc is formed, the strength of the outer connection portion of the strut 53b can be increased. Furthermore, in this embodiment as well, in the region of the strut 53b that includes the inner connection portion connected to the inner cover 61, a thin-walled portion with a thinner circumferential thickness Dc than the thick-walled portion is formed, thereby reducing resistance during the process in which compressed air Acom is discharged from the diffuser 26a and passes alongside the strut 53b.

[0070] As described above, cooling air ACL may be supplied directly from the cooling air supply device 1 to the inner passage P4 of the inner cover 61 without forming an outer space P1 in the outer cover 51b and strut spaces 58 in the multiple struts 53b. Although this embodiment is a modification of the second embodiment, in the first embodiment as well, cooling air ACL may be supplied directly from the cooling air supply device 1 to the inner passage P4 of the inner cover 61 without forming an outer space P1 in the outer diffuser 27 which is the outer cover and strut spaces 58 in the multiple struts 53.

[0071] "Fourth embodiment of the intermediate shaft cover" A fourth embodiment of the intermediate shaft cover will be described with reference to Figure 8.

[0072] The intermediate shaft cover 50c in this embodiment is a modified version of the intermediate shaft cover 50 in the first embodiment. The intermediate shaft cover 50c in this embodiment is the same as the intermediate shaft cover 50 in the first embodiment, except that it lacks the flange 52 of the intermediate shaft cover 50 in the first embodiment.

[0073] In this embodiment, the multiple struts 53 are directly connected to the cooling air jacket 27j of the outer diffuser 27, which is the outer cover. Therefore, the intermediate shaft cover 50c in this embodiment does not have a flange 52.

[0074] Although this embodiment is a modification of the first embodiment, in the second and third embodiments as well, the flange 52 may be omitted and the multiple struts 53, 53b may be directly connected to the outer covers 51, 51b. That is, the multiple struts 53, 53b only need to be directly connected to an annular member such as a part of the outer diffuser 27, a part of the outer covers 51, 51b, or the flange 52. In this case, the annular member needs to be located at the downstream end of Da on the axis of the outer diffuser, on the outer circumference of the diffuser space S. Furthermore, this annular member needs to be provided so as to be immovable relative to the gas turbine casing 14.

[0075] Furthermore, this disclosure is not limited to the embodiments described above. Various additions, modifications, substitutions, and partial deletions are possible, provided that they do not depart from the conceptual idea and spirit of the present invention derived from the claims and their equivalents.

[0076] "Addendum" The intermediate shaft covers 50, 50a, 50b, and 50c in each of the above embodiments are, for example, as follows.

[0077] (1) The intermediate shaft cover in the first embodiment is applied to the following gas turbine 10. The gas turbine 10 comprises a gas turbine rotor 11 that can rotate about an axis Ar, and a gas turbine casing 14 that covers the outer circumference of the gas turbine rotor 11. The gas turbine rotor 11 has a gas turbine rotor shaft 12 extending in the axial direction Da, a plurality of compressor blade rows 23 provided on the portion of the gas turbine rotor shaft 12 on the upstream side Dau of the axis, and a plurality of turbine blade rows 43 provided on the portion of the gas turbine rotor shaft 12 on the downstream side Da, spaced apart from the plurality of compressor blade rows 23. The intermediate shaft covers 50, 50a, 50b, and 50c include diffusers 26, 26a through which compressed air Acom that has passed through the plurality of compressor blade rows 23 can pass, forming an annular diffuser space S centered on the axis Ar; a cylindrical inner cover 61 located downstream of the diffusers 26, 26a on the axis Da, covering the intermediate rotor shaft 12m between the plurality of compressor blade rows 23 and the plurality of turbine blade rows 43 in the gas turbine rotor shaft 12; annular outer covers 27, 51, and 51b that cover the outer circumference of the diffuser space S and are connected to the gas turbine casing 14; and struts 53 and 53b extending radially outward from the outer circumference of the inner cover 61 toward the axis Ar, and directly or indirectly connected to the outer covers 27, 51, and 51b. The struts 53, 53b each have a thick-walled portion 55 with a thickness in the circumferential direction Dc relative to the axis Ar, and a thin-walled portion 57 with a thickness in the circumferential direction Dc that is thinner than the thick-walled portion 55. The thick-walled portion 55 is formed in a region of the struts 53, 53b that includes an outer connecting portion 54o, which is directly or indirectly connected to the outer covers 27, 51, 51b, including the radially outer end Dro. The thin-walled portion 57 is formed in a region of the struts 53, 53b that includes an inner connecting portion 54i, which is connected to the inner cover 61, including the radially inner end Dri, which is relative to the axis Ar.

[0078] In this embodiment, in the struts 53, 53b, a thin-walled portion is provided in the region including the outer connecting portion 54o which is directly or indirectly connected to the outer covers 27, 51, 51b. From Section 57A thick-walled portion 55 with a thickness in the circumferential direction Dc is formed. This increases the strength of the outer connection portion 54o in the struts 53 and 53b. Moreover, in this embodiment, a thin-walled portion 57 with a thickness in the circumferential direction Dc thinner than the thick-walled portion 55 is formed in the region of the struts 53 and 53b that includes the inner connection portion 54i connected to the inner cover 61. This prevents the width of the flow path of compressed air Acom discharged from the diffusers 26 and 26a and passing alongside the struts 53 and 53b from narrowing. Therefore, in this embodiment, resistance during the process of compressed air Acom passing alongside the struts 53 and 53b can be reduced.

[0079] (2) The intermediate shaft cover in the second embodiment is In the intermediate shaft covers 50, 50a, 50b, and 50c of the first embodiment, the struts 53 and 53b have a thickness-gradual change portion 56 between the thick portion 55 and the thin portion 57, where the thickness in the circumferential direction Dc gradually decreases from the thick portion 55 toward the thin portion 57.

[0080] In this embodiment, since a thickness variation section 56 exists between the thick section 55 and the thin section 57, stress concentration between the thick section 55 and the thin section 57 can be suppressed.

[0081] (3) The intermediate shaft cover in the third embodiment is In the intermediate shaft covers 50, 50a, 50b, 50c in the first or second embodiment, the diffusers 26, 26a include outer diffusers 27, 27a that define the outer edge of the diffuser space S and an inner diffuser 28 that defines the inner edge of the diffuser space S. The outer diffusers 27, 27a are located downstream of the axis. Dad The inner diameter is formed to gradually increase as the struts 53 and 53b move. In the inner circumferential surface of the outer diffusers 27 and 27a, the portion Dri radially inward from the extension line L of the generatrix that intersects with the virtual plane containing the axis Ar is the thin-walled portion 57.

[0082] In this embodiment, most of the compressed air Acom discharged from the diffusers 26, 26a and passing alongside the struts 53, 53b passes radially inward from the extension line L of the generatrix on the inner circumferential surface of the outer diffusers 27, 27a. Therefore, in this embodiment, resistance during the process of compressed air Acom passing alongside the struts 53, 53b can be suppressed.

[0083] (4) The intermediate shaft cover in the fourth embodiment is In the intermediate shaft cover 50 in any one of the first to third embodiments described above, the diffuser 26 has an outer diffuser 27 that defines the outer edge of the diffuser space S and an inner diffuser 28 that defines the inner edge of the diffuser space S. The outer cover 27 is the outer diffuser.

[0084] The outer covers 27, 51, and 51b may be separate components from the outer diffusers 27 and 27a, but as in this embodiment, they may be the outer diffuser 27.

[0085] (5) The intermediate shaft cover in the fifth embodiment is In the intermediate shaft covers 50, 50a, 50c of any one of the first to fourth embodiments described above, a passage cover 59 is provided that defines a strut passage P3, which is part of a cooling air passage P, to the turbine rotor shaft 42, in which the plurality of turbine blade rows 43 are provided within the gas turbine rotor shaft 12, allowing cooling air ACL from outside the gas turbine casing 14 to be supplied. The outer covers 27, 51 have an outer space P1 into which cooling air ACL from outside the gas turbine casing 14 can flow, as part of the cooling air passage P. The strut 53 has a strut space 58 that communicates with the outer space P1. The passage cover 59 is arranged within the strut space 58. The outer space P1 within the outer covers 27, 51 and the strut passage P3 within the passage cover 59 are connected by a connecting passage P2, which is part of the cooling air passage P. The passage cover 59 is not arranged within the connecting passage P2. The inner cover 61 has an inner passage P4 that is part of the cooling air passage P, communicates with the strut passage P3, and can send cooling air ACL from the strut passage P3 to the turbine rotor shaft 42.

[0086] In this embodiment, the cooling air passage P, which consists of an outer space P1, a connecting passage P2, a strut passage P3, and an inner passage P4, can deliver cooling air ACL from outside the gas turbine casing 14 to the turbine rotor shaft 42. Furthermore, in this embodiment, the passage cover 59 in the strut space 58 is not located in the connecting passage P2, which is part of the cooling air passage P. Therefore, in this embodiment, the area around the connecting passage P2 can be directly cooled by the cooling air ACL flowing through the connecting passage P2. Thus, in this embodiment, the outer connection portion 54o of the strut 53 can be efficiently cooled, and the decrease in strength due to high temperature of the outer connection portion 54o of the strut 53 can be suppressed.

[0087] (6) The intermediate shaft cover in the sixth embodiment is In any one of the first to fifth embodiments, the intermediate shaft covers 50, 50a, and 50b further include a flange 52 that forms an annular shape with respect to the axis Ar and is connected to the outer covers 27, 51, and 51b. The struts 53 and 53b are connected to the flange 52.

[0088] The radially outer ends of the struts 53, 53b may be directly connected to the outer covers 27, 51, 51b, or, as in this embodiment, they may be indirectly connected to the outer covers 27, 51, 51b via the flange 52.

[0089] The gas turbine 10 in each of the above embodiments can be understood, for example, as follows. (7) The gas turbine in the seventh embodiment is The gas turbine comprises the intermediate shaft covers 50, 50a, 50b, and 50c described in the first to sixth embodiments, the gas turbine rotor 11, the gas turbine casing 14, and a combustor 30 attached to the gas turbine casing 14, which burns fuel F in compressed air Acom that has passed through the diffuser space S to generate combustion gas G. The combustor 30 is configured such that the combustion gas G is guided to the plurality of turbine blade rows 43. [Industrial applicability]

[0090] According to one aspect of this disclosure, it is possible to increase the strength of the gas turbine struts while suppressing resistance to the airflow from the compressor. Running costs can be reduced during the liquefaction and vaporization of gases. [Explanation of Symbols]

[0091] 1: Cooling air supply device 2: Extraction line 3: Air conditioner 4,4b: Cooling air line 5: Boost compressor 9: Generator 10: Gas Turbine 11: Gas turbine rotor 12: Gas turbine rotor shaft 12m: Intermediate rotor shaft 14: Gas turbine casing 15: Intermediate casing 16: Exhaust casing 20: Compressor 21: Compressor rotor 22: Compressor rotor shaft 23: Compressor blade row 24: Compressor casing 25: Compressor stator blade row 26,26a: Diffuser 27,27a: Outer diffuser 27m: Outer diffuser body 27j: Cooling air jacket 28: Inner diffuser 30: Combustor 31: Burner 32: Combustion tube (or tail tube) 40: Turbine 41: Turbine Rotor 42: Turbine rotor shaft 42p: Cooling air passage 43: Turbine blade row 43b: Moving blade 43p: Cooling air passage 44: Turbine casing 45: Turbine stator blade row 49: Combustion gas flow path 50, 50a, 50b, 50c: Intermediate shaft cover 51, 51b: Outer cover 51m: Outer cover body 51j: Cooling Air Jacket 52: Flange 53, 53b: Strut 54o:Outside connection part 54i: Internal connection 55:Thick part 56: Areas where wall thickness gradually changes 57: Thin-walled section 58: Strut space 59: Aisle cover 61: Inner cover 62: Inner first cover 63: Inner second cover P, Pb: Cooling air passage P1: Outside space P2: Connecting passage P3: Strut aisle P4: Inner passage S: Diffuser space A: Air Acom: Compressed air ACL: Cooling air F:Fuel G: Combustion gas EG: Exhaust gas Ar: Axis line Da: Axial direction Dau: Axis upstream side Dad: Downstream side of the axis Dc: Circumferential direction Dr: Radial direction Dri: Radial inner side Dro: Radial outward L: Extension line

Claims

1. A gas turbine rotor that can rotate around its axis, A gas turbine casing covering the outer circumference of the gas turbine rotor, Equipped with, The aforementioned gas turbine rotor is The gas turbine rotor shaft extends in the axial direction, A plurality of compressor blade rows are provided on the upstream side of the gas turbine rotor shaft, among the upstream and downstream sides of the axial direction, A plurality of turbine blade rows are provided on the downstream portion of the gas turbine rotor shaft, spaced apart from the plurality of compressor blade rows downstream of the axis, Having, In the intermediate shaft cover of a gas turbine, A diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, and which forms an annular diffuser space centered on the axis, Downstream of the diffuser along the axis, a cylindrical inner cover covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows within the gas turbine rotor shaft, An annular outer cover that covers the outer periphery of the diffuser space and is connected to the gas turbine casing, A strut extending radially outward from the outer circumference of the inner cover with respect to the axis, and directly or indirectly connected to the outer cover, Equipped with, The strut has a thick-walled portion with a greater circumferential thickness relative to the axis, and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The aforementioned thickened portion is formed in a region of the strut that includes an outer connecting portion which is directly or indirectly connected to the outer cover, including the radially outer end. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. The diffuser comprises an outer diffuser defining the outer edge of the diffuser space and an inner diffuser defining the inner edge of the diffuser space. The outer diffuser is formed such that its inner diameter gradually increases towards the downstream side of the axis. In the strut, the portion radially outside the extension of the generatrix that intersects the virtual plane containing the axis on the inner circumferential surface of the outer diffuser includes the thickened portion. It is being Intermediate shaft cover.

2. A gas turbine rotor that can rotate around its axis, A gas turbine casing covering the outer circumference of the gas turbine rotor, Equipped with, The aforementioned gas turbine rotor is The gas turbine rotor shaft extends in the axial direction, A plurality of compressor blade rows are provided on the upstream side of the gas turbine rotor shaft, among the upstream and downstream sides of the axial direction, A plurality of turbine blade rows are provided on the downstream portion of the gas turbine rotor shaft, spaced apart from the plurality of compressor blade rows downstream of the axis, Having, In the intermediate shaft cover of a gas turbine, A diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, and which forms an annular diffuser space centered on the axis, Downstream of the diffuser along the axis, a cylindrical inner cover covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows within the gas turbine rotor shaft, An annular outer cover that covers the outer periphery of the diffuser space and is connected to the gas turbine casing, A strut extending radially outward from the outer circumference of the inner cover with respect to the axis, and directly or indirectly connected to the outer cover, Equipped with, The strut has a thick-walled portion with a greater circumferential thickness relative to the axis, and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The aforementioned thickened portion includes an outer connecting portion in the strut that is directly or indirectly connected to the outer cover, including the radially outer end, and is formed in a region radially outward from the diffuser space. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. In the strut, the circumferential thickness in the portion radially inward from the thickened portion is thinner than the circumferential thickness in the thickened portion. Intermediate shaft cover.

3. A gas turbine rotor that can rotate around its axis, A gas turbine casing covering the outer circumference of the gas turbine rotor, Equipped with, The aforementioned gas turbine rotor is The gas turbine rotor shaft extends in the axial direction, A plurality of compressor blade rows are provided on the upstream side of the gas turbine rotor shaft, among the upstream and downstream sides of the axial direction, A plurality of turbine blade rows are provided on the downstream portion of the gas turbine rotor shaft, spaced apart from the plurality of compressor blade rows downstream of the axis, Having, In the intermediate shaft cover of a gas turbine, A diffuser through which compressed air that has passed through the plurality of compressor blade rows can pass, and which forms an annular diffuser space centered on the axis, Downstream of the diffuser along the axis, a cylindrical inner cover covers the intermediate rotor shaft between the plurality of compressor blade rows and the plurality of turbine blade rows within the gas turbine rotor shaft, An annular outer cover that covers the outer periphery of the diffuser space and is connected to the gas turbine casing, A strut extending radially outward from the outer circumference of the inner cover with respect to the axis, and directly or indirectly connected to the outer cover, Equipped with, The strut has a thick-walled portion with a greater circumferential thickness relative to the axis, and a thin-walled portion with a thinner circumferential thickness than the thick-walled portion. The aforementioned thickened portion is formed in the strut in a region that includes an outer connecting portion that is directly or indirectly connected to the outer cover, including the radially outer end. The thin-walled portion is formed in a region of the strut that includes an inner connecting portion, which is connected to the inner cover and includes the radially inner end with respect to the axis. The diffuser comprises an outer diffuser defining the outer edge of the diffuser space and an inner diffuser defining the inner edge of the diffuser space. The outer diffuser is formed such that its inner diameter gradually increases towards the downstream side of the axis. In the strut, the portion radially inward from the extension of the generatrix that intersects the virtual plane containing the axis on the inner circumferential surface of the outer diffuser is the thin-walled portion. Intermediate shaft cover.

4. In the intermediate shaft cover according to any one of claims 1 to 3, The strut has a thickness-gradual change portion between the thick portion and the thin portion, where the circumferential thickness gradually decreases from the thick portion toward the thin portion. Intermediate shaft cover.

5. In the intermediate shaft cover according to claim 1 or 2, The diffuser comprises an outer diffuser defining the outer edge of the diffuser space and an inner diffuser defining the inner edge of the diffuser space. The outer cover is the outer diffuser. Intermediate shaft cover.

6. An intermediate shaft cover according to any one of claims 1 to 3, The turbine rotor shaft, on which the plurality of turbine blade rows are provided, is equipped with a passage cover that defines a strut passage, which is part of a cooling air passage through which cooling air can be supplied from outside the gas turbine casing. The outer cover has an outer space into which cooling air from outside the gas turbine casing can flow, as part of the cooling air passage. The strut has a strut space that communicates with the outer space, The passage cover is positioned within the strut space. The outer space within the outer cover and the strut passage within the passage cover are connected by a connecting passage which is part of the cooling air passage. The aforementioned passage cover is not located within the aforementioned connecting passage. The inner cover has an inner passage that, as part of the cooling air passage, communicates with the strut passage and is capable of supplying cooling air from the strut passage to the turbine rotor shaft. Intermediate shaft cover.

7. In the intermediate shaft cover according to any one of claims 1 to 3, It further comprises a flange that forms an annular shape with respect to the aforementioned axis and is connected to the outer cover, The strut is connected to the flange, Intermediate shaft cover.

8. An intermediate shaft cover according to any one of claims 1 to 3, The aforementioned gas turbine rotor, The aforementioned gas turbine casing and, A combustor is attached to the gas turbine casing and generates combustion gas by burning fuel in compressed air that has passed through the diffuser space, Equipped with, The combustor is formed such that the combustion gas is guided to the plurality of turbine blade rows. Gas turbine.

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