Intermediate shaft cover and gas turbine fitted with it

Abstract

This intermediate shaft cover includes a cylindrical inner cover covering an intermediate rotor shaft; an annular outer cover covering an outer peripheral side of a diffuser space and connected to a gas turbine casing; and a stay extending radially outward from an outer periphery of an inner cover and directly or indirectly connected to the outer cover. The stay has a thick wall portion and a thin wall portion having a circumferential thickness smaller than that of the thick wall portion. The thick wall portion is formed in a region of the stay including an outer connecting portion directly or indirectly connected to the outer cover. The thin wall portion is formed in a region of the stay 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 provided therewith.

[0002] Priority is claimed to Japanese Patent Application No. 2022-160173 filed on October 4, 2022, the contents of which are incorporated herein by reference. State of the art

[0003] A gas turbine includes a compressor that compresses air, a combustion chamber that burns fuel in the air compressed by the compressor to produce a combustion gas, a turbine driven by the combustion gas, and an intermediate casing.

[0004] The compressor includes a compressor rotor rotatable about an axis, a compressor housing covering the compressor rotor, and a diffuser. The compressor rotor has a compressor rotor shaft extending in an axial direction centered on the axis, and a plurality of compressor rotor blade rows provided on the compressor rotor shaft. The diffuser forms an annular diffuser space through which air that has passed through the plurality of compressor rotor 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 includes a turbine rotor rotatable about the axis and a turbine housing covering the turbine rotor.The turbine rotor includes a turbine rotor shaft extending in an axial direction centered on the axis and a plurality of turbine rotor blade rows provided on the turbine rotor shaft.

[0005] The compressor rotor and the turbine rotor are connected to each other to form a gas turbine rotor. In the gas turbine rotor, an intermediate rotor shaft, in which rotor blade rows are not provided, is formed between the plurality of compressor rotor blade rows and the plurality of turbine rotor blade rows in the axial direction. An intermediate casing covering the intermediate rotor shaft is arranged between the compressor casing and the turbine casing. The compressor casing, the intermediate casing, and the turbine casing are connected to each other to form a gas turbine rotor. The combustor is attached to the intermediate casing.

[0006] The gas turbine described in the following PTL 1 further includes an intermediate shaft cover. The intermediate shaft cover includes a tubular inner cover covering an outer periphery of the intermediate rotor shaft, and a plurality of supports extending from an outer periphery of the inner cover in a radial direction with respect to the axis. The plurality of supports are arranged in a circumferential direction with respect to the axis. One end of the support on a radially outer side is connected to one end of the outer diffuser on an axially downstream side.

[0007] The air expelled from the compressor's diffuser passes through spaces between the multiple supports and flows into the combustion chamber. Citation listPatent literature

[0008] [PTL 1] International Publication No. WO2018 / 181902 Summary of the inventionTechnical problem

[0009] In the field of gas turbines including an intermediate shaft cover, there is a need to increase the strength of a connecting portion between a plurality of supports and an outer diffuser. Meanwhile, there is also a need in this field to suppress resistance in a process where air passes through spaces between a plurality of supports after being discharged from a diffuser of a compressor.

[0010] Therefore, an object of the present disclosure is to provide an intermediate shaft cover capable of suppressing resistance of a flow of air from the compressor while increasing strength of a support, and a gas turbine provided with the same. Solution to the problem

[0011] The intermediate shaft cover as an aspect to achieve the object is applied to the following gas turbine.

[0012] The gas turbine includes a gas turbine rotor rotatable about an axis and a gas turbine casing covering an outer periphery of the gas turbine rotor. The gas turbine rotor includes a gas turbine rotor shaft extending in an axial direction, a plurality of compressor rotor blade rows provided in a portion of the gas turbine rotor shaft on an axial upstream side among the axial upstream side and an axial downstream side in the axial direction, and a plurality of turbine rotor blade rows provided in a portion of the gas turbine rotor shaft on the axial downstream side with a distance from the plurality of compressor rotor blade rows to the axial downstream side.

[0013] The intermediate shaft cover includes a diffuser through which compressed air that has passed through the plurality of compressor rotor blade rows can flow and which forms an annular diffuser space centered on the axis, a tubular inner cover that covers an intermediate rotor shaft between the plurality of compressor rotor blade rows and the plurality of turbine rotor blade rows at the gas turbine rotor shaft, on the axial downstream side with respect to the diffuser, an annular outer cover that covers an outer peripheral side of the diffuser space and is connected to the gas turbine casing, and a support that extends from an outer periphery of the inner cover to a radially outer side with respect to the axis and that is directly or indirectly connected to the outer cover.The stay includes a thick wall portion having a large thickness in a circumferential direction with respect to the axis, and a thin wall portion having a smaller thickness in the circumferential direction than the thickness of the thick wall portion. The thick wall portion is formed in a region including an outer connecting portion, which has one end on the radially outer side and is directly or indirectly connected to the outer cover, in the stay. The thin wall portion is formed in a region including an inner connecting portion, which has one end on the radially inner side with respect to the axis and is connected to the inner cover, in the stay.

[0014] In the present aspect, in the stay, a thick wall portion having a greater thickness in the circumferential direction than the thickness of the thin wall portion is formed in a region including an outer connecting portion connected to the outer cover directly or indirectly. Therefore, strength of the outer connecting portion in the stay can be increased. Furthermore, in the present aspect, in the stay, a thin wall portion having a smaller thickness in the circumferential direction than the thickness of the thick wall portion is formed in the region including the inner connecting portion connected to the inner cover. Therefore, it is possible to suppress narrowing of a width of a flow path of the compressed air discharged from the diffuser to pass one side of the stay.Therefore, in the present aspect, it is possible to suppress resistance in a process in which the compressed air passes the side of the support.

[0015] The gas turbine as one aspect for achieving the object includes an intermediate shaft cover as the one aspect, the gas turbine rotor, the gas turbine casing, and a combustor attached to the gas turbine casing and generating combustion gas by burning fuel in compressed air flowed into the diffuser space.

[0016] The combustion chamber is designed so that the combustion gas is directed to the several rows of turbine rotor blades. Advantageous effects of the invention

[0017] In one aspect of the present disclosure, it is possible to suppress the resistance of the flow of air from the compressor while increasing the strength of the support. Brief description of the drawings Fig. 1 is a schematic configuration view of gas turbine equipment in an embodiment according to the present disclosure. Fig. 2 is a cross-sectional view of a main part of a gas turbine around an intermediate shaft cover in a first embodiment according to the present disclosure. Fig. 3 is a cross-sectional view of a main part of the intermediate shaft cover in the first embodiment according to the present disclosure. Fig. 4 is a development view showing a state in which the intermediate shaft cover in the first embodiment according to the present disclosure is developed in a circumferential direction, as viewed from a radially outer side. Fig. 5 is a cross-sectional view along line VV in Fig. 4. Fig. 6 is 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. Fig. 7 is 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. Fig. 8 is 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. Description of Embodiments

[0018] Hereinafter, an embodiment of gas turbine equipment incorporating 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. “Embodiment of gas turbine equipment”

[0019] An embodiment of the gas turbine equipment is described below with reference to Fig. 1 described.

[0020] As in Fig. 1, the gas turbine equipment of the present embodiment includes a gas turbine 10 and a cooling air supply device 1 that supplies cooling air Acl to some components of the gas turbine 10.

[0021] The gas turbine 10 includes a compressor 20 that compresses air A to produce compressed air Acom, a plurality of combustion chambers 30 that combust fuel F in the compressed air Acom to produce combustion gas G, a turbine 40 driven by the combustion gas G having a high temperature and high pressure, an exhaust casing 16 through which exhaust gas EG, which is the combustion gas G discharged from the turbine 40, flows, an intermediate casing 15, and an intermediate shaft cover 50.

[0022] The compressor 20 includes a compressor rotor 21 rotatable about an axis Ar, a compressor casing 24 covering the compressor rotor 21, a plurality of compressor stator blade rows 25, and a diffuser. The turbine 40 includes a turbine rotor 41 rotatable about the axis Ar, a turbine casing 44 covering the turbine rotor 41, and a plurality of turbine blade rows 45. Hereinafter, an extending direction of the axis Ar is referred to as an axial direction Da, a circumferential direction centered on the axis Ar is simply referred to as a circumferential direction Dc, and a direction perpendicular to the axis Ar is referred to as a radial direction Dr. Furthermore, a side in the axial direction Da is referred to as an axial upstream side Dau, and a side opposite thereto is referred to as an axial downstream side Dad.In addition, a side closer to the axis Ar in the radial direction Dr is called a radial inner side Dri, and a side opposite thereto is called a radial outer side Dro.

[0023] The compressor 20 is arranged on the axial upstream side Dau with respect to the turbine 40. Furthermore, the outlet casing 16 is arranged on the axial downstream side Dad with respect to the turbine 40.

[0024] The compressor rotor 21 includes a compressor rotor shaft 22 extending in the axial direction Da centered on 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. Any one compressor rotor blade row 25 among the plurality of compressor rotor blade rows 25 is arranged on each axial upstream side Dau of the plurality of compressor rotor blade rows 23. Each compressor stator blade row 25 is provided within the compressor housing 24. Each compressor stator blade row 25 is composed of a plurality of stator blades arranged in the circumferential direction Dc.

[0025] The diffuser 26 forms a diffuser space S through which air that has passed through the multiple compressor rotor blade rows 23 passes. The diffuser space S is an annular space centered on the axis Ar.

[0026] The turbine rotor 41 includes a turbine rotor shaft 42 extending in the axial direction Da and centered on 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 rotor blade row 43 is composed of the plurality of rotor blades arranged in the circumferential direction Dc. Any one turbine blade row 45 among the plurality of turbine blade rows 45 is arranged on each axial upstream side Dau of the plurality of turbine rotor blade rows 43. Each turbine stator blade row 45 is provided within the turbine casing 44. Each turbine stator blade row 45 is composed of the plurality of stator blades arranged in the circumferential direction Dc.An annular space on an inner peripheral side of the turbine casing 44 on an outer peripheral side of the turbine rotor shaft 42 forms a combustion gas passage 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 the combustion gas passage 49.

[0027] 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, the gas turbine rotor 11 includes a gas turbine rotor shaft 12 extending in the axial direction Da centered on the axis Ar, and the plurality of compressor rotor blade rows 23 and the plurality of turbine rotor blade rows 43. In the gas turbine rotor shaft 12, an intermediate rotor shaft 12m is formed between the plurality of compressor rotor blade rows 23 and the plurality of turbine rotor blade rows 43. For example, a rotor of a generator 9 is connected to the gas turbine rotor 11. The intermediate casing 15 is arranged between the compressor casing 24 and the turbine casing 44 in the axial direction Da and covers the intermediate rotor shaft 12m. The compressed air Acom, which is discharged from the diffuser 26 of the compressor 20, flows into the intermediate housing 15.The compressor housing 24, the intermediate housing 15, the turbine housing 44 and the exhaust housing 16 are connected together to form a gas turbine housing 14.

[0028] The intermediate shaft cover 50 is arranged in the intermediate housing 15 and covers an outer peripheral side of the intermediate rotor shaft 12m.

[0029] The plurality of combustion chambers 30 are arranged in a circumferential direction Dc and attached to the intermediate casing 15. The combustion chamber 30 includes a combustion cylinder (or transition piece) 32 that supplies the combustion gas G having a high temperature and high pressure to the combustion gas passage 49 of the turbine 40, and a plurality of burners 31 that inject the fuel F together with the compressed air Acom into a combustion cylinder 32. The combustion cylinder 32 is configured so that the combustion gas G can be supplied into the combustion gas passage 49 of the turbine 40.

[0030] The cooling air supply device 1 includes a vent air line 2 for venting the compressed air Acom in the intermediate housing 15 from the intermediate housing 15, a cooler 3 for cooling the compressed air Acom that has flowed through the vent air line 2, a cooling air line 4 for guiding the cooling air Acl, which is the compressed air Acom 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.

[0031] The compressor 20 draws in outside air A and compresses the air A to generate compressed air Acom. The 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 combustion chamber 30. The burner 31 of the combustion chamber 30 injects the compressed air Acom together with the fuel F supplied from the outside into the combustion cylinder 32. In the combustion cylinder 32, the fuel F is burned in the compressed air Acom to become combustion gas G. The combustion gas G is supplied to the combustion gas passage 49 of the turbine 40 to rotate the turbine rotor 41. “First embodiment of intermediate shaft cover”

[0032] A first embodiment of the intermediate shaft cover is described with reference to Fig. 2 to 5.

[0033] As in Fig. 2, the intermediate shaft cover 50 in the present embodiment includes the diffuser 26, an inner cover 61, a flange 52, a plurality of supports 53, and a channel cover 59 provided for each of the plurality of supports 53.

[0034] The diffuser 26 is the diffuser 26 of the compressor 20 described above. Therefore, the diffuser 26 is a component of the compressor 20 and is also a component of the intermediate shaft cover 50. As in Fig. 3 to 5, the diffuser 26 includes an outer diffuser 27 defining an outer peripheral edge of the annular diffuser space S and an inner diffuser 28 defining an inner peripheral edge of the diffuser space S. Fig. 3 is a cross-sectional view of a main part of the intermediate shaft cover 50. Fig. 4 is a development view showing a state in which the intermediate shaft cover 50 is developed in the circumferential direction Dc and viewed from the radial outer side Dro. Fig. 5 is a cross-sectional view along line VV in Fig. 4.

[0035] The inner diffuser 28 has a tubular shape centered on the axis Ar.

[0036] The outer diffuser 27 is an outer cover with respect to the inner cover 61. The outer diffuser 27 includes a tubular outer diffuser main body 27m centered on the axis Ar, and a cooling air jacket 27j provided on an outer periphery of the outer diffuser main body 27m, which is a portion of the outer diffuser main body 27m on the axial downstream side Dad. The outer diffuser main body 27m defines the outer peripheral edge of the annular diffuser space S. The outer diffuser main body 27m is formed such that an inner diameter gradually increases toward the axial downstream side Dad. One end of the outer diffuser 27 on the axial upstream side Dau is attached to the gas turbine casing 14. The air cooling jacket 27j has an annular shape centered on the axis Ar.The cooling air casing 27j, together with the outer diffuser main body 27m, forms an annular outer space P1 on an outer peripheral side of the outer diffuser main body 27m, which is a portion of the outer diffuser main body 27m on the axial downstream side Dad. The cooling air duct 4 of the cooling air supply device 1 is connected to the cooling air jacket 27j. The cooling air Acl from the cooling air duct 4 can flow into the outer space P1 at the cooling air jacket 27j.

[0037] The flange 52 forms an annular shape centered on the axis Ar and is connected to the annular cooling air jacket 27j centered on the axis Ar. The flange 52 is arranged on an outer peripheral side of the diffuser space S at one end of the outer diffuser 27 on the axial downstream side Dad.

[0038] The inner cover 61 is arranged in a region on the radial inner side Dri with respect to the diffuser 26, which is located on the axial downstream side Dad with respect to the diffuser 26 and on the axial upstream side Dau with respect to the plurality of turbine rotor blade rows 43. The inner cover 61 is formed in a tubular shape centered on the axis Ar and covers the intermediate rotor shaft 12m. The inner cover 61 includes a tubular first inner cover 62 centered on the axis Ar and a tubular second inner cover 63 centered on the axis Ar. One end on the axial upstream side Dau of the first inner cover 62 is connected to one end on the axial downstream side Dad of the inner diffuser 28. The second inner cover 63 is arranged on the radial inner side Dri of the first inner cover 62 and is connected to the first inner cover 62.The second inner cover 63 forms together with the first inner cover 62 an annular inner channel P4 extending in the axial direction Da on the radial outer side Dro of the intermediate rotor shaft 12m, which is the radial inner side Dri of the first inner cover 62.

[0039] The plurality of supports 53 are arranged in the circumferential direction Dc. Each of the supports 53 extends from an outer periphery of the first inner cover 62 toward the radially outer side Dro and is connected to the flange 52. Therefore, the plurality of supports 53 are connected to the outer diffuser 27 as the outer cover through the flange 52.

[0040] Each support 53 has a thick wall section 55, a thin wall section 57 and a section 56 of gradual change in wall thickness. In the support 53 of Fig. 3, a portion having a lattice pattern is the thick wall portion 55, a portion having a stripe pattern is the gradual change in wall thickness portion 56, and a portion without a pattern is the thin wall portion 57. The thick wall portion 55 is formed at the stay 53 in a region including an outer connecting portion 54o that is directly connected to the outer diffuser 27 as the outer cover and that has one end on the radially outer side Dro. The thin wall portion 57 is formed in a region including an inner connecting portion 54i that has one end on the radially inner side Dri and that is connected to the inner cover 61 at the stay 53. A thickness of the thin wall portion 57 in the circumferential direction Dc is smaller than a thickness of the thick wall portion 55 in the circumferential direction Dc.The wall thickness gradual change portion 56 is formed between the thick wall portion 55 and the thin wall portion 57 at the support 53. A thickness of the wall thickness gradual change portion 56 in the circumferential direction Dc gradually decreases from the thick wall portion 55 toward the thin wall portion 57. The thickness of the wall thickness gradual change portion 56 is equal to the thickness of the thick wall portion 55 at a boundary between the wall thickness gradual change portion 56 and the thick wall portion 55, and is equal to the thickness of the thin wall portion 57 at a boundary between the wall thickness gradual change portion 56 and the thin wall portion 57.

[0041] In the case of the support 53, a section on the radial inner side Dri is arranged with respect to an extension line L (see Fig. 3) a generatrix intersecting a virtual plane containing the axis Ar on an inner peripheral surface of the outer diffuser 27, the thin wall portion 57. In other words, in the support 53, a portion on the radially outer side Dro with respect to the extension line L is the portion 56 of gradual change of wall thickness and the thick wall portion 55.

[0042] A cooling air duct P, through which the cooling air Acl from the cooling air line 4 of the cooling air supply device 1 can be supplied to the turbine rotor shaft 42, is formed at the intermediate shaft cover 50. The outer space P1 of the above-described outer diffuser 27 is a part of the cooling air duct P.

[0043] A support space 58 is formed at each support 53. The support space 58 communicates with the exterior space P1 through a connecting passage P2, which is a part of the cooling air passage P. The support space 58 extends from a connecting surface with the flange 52 at the support 53 to an inner peripheral surface of the first inner cover 62. The connecting passage P2 is formed in the cooling air jacket 27j and the flange 52 of the outer diffuser 27.

[0044] The duct cover 59, which defines a support duct P3 that is a part of the cooling air duct P, is disposed in the support space 58. The duct cover 59 is not disposed in the connecting duct P2. One end of the support duct P3 communicates with the connecting duct P2. Moreover, the other end of the support duct P3 communicates with the inner duct P4 of the inner cover 61. That is, the outer space P1, the connecting duct P2, the support duct P3, and the inner duct P4 described above communicate with each other to form the cooling air duct P configured to supply the cooling air Acl from the outside of the gas turbine casing 14 to the turbine rotor shaft 42.

[0045] As in Fig. 2, a cooling air passage 42p communicating with the cooling air passage P of the intermediate shaft cover 50 is formed at the turbine rotor shaft 42. Among the plurality of turbine rotor blade rows 43 attached to the turbine rotor shaft 42, a cooling air passage 43p communicating with the cooling air passage 42p of the turbine rotor shaft 42 is formed at the axialmost upstream side Dau of a plurality of rotor blades 43b constituting the turbine rotor blade row 43. The cooling air Acl from the cooling air passage P of the intermediate shaft cover 50 is supplied to the cooling air passage 43p of the rotor blade 43b through the cooling air passage 42p of the turbine rotor shaft 42. The cooling air Acl cools the rotor blade 43b in a process of passing through the cooling air passage 43p of the rotor blade 43b. The cooling air Acl flows out of an outer surface of the rotor blade 43b into the combustion gas channel 49.

[0046] In the present embodiment, as described, in the stay 53, the thick wall portion 55 having a greater thickness in the circumferential direction Dc than the thickness of the thin wall portion 57 is formed in the region including the outer connecting portion 54o that is directly or indirectly connected to the outer cover 27, which is the outer cover. Therefore, the strength of the outer connecting portion 54o in the stay 53 can be increased. Furthermore, in the present embodiment, in the stay 53, in the region including the inner connecting portion 54i that is connected to the inner cover 61, the thin wall portion 57 having a smaller thickness in the circumferential direction Dc than the thickness of the thick wall portion 55 is formed. Therefore, it is possible to suppress narrowing of a flow path width of the compressed air Acom that is discharged from the diffuser 26 and passes through one side of the stay 53.Therefore, in the present embodiment, it is possible to suppress resistance in a process in which the compressed air Acom passes the side of the support 53.

[0047] A majority of the compressed air Acom discharged from the diffuser 26 and passing the side of the stay 53 flows through the radially inner side Dri with respect to the extension line L of the generatrix on the inner peripheral surface of the outer diffuser 27. In the present embodiment, in the stay 53, the thin wall portion 57 is located on the radially inner side Dri with respect to the extension line L, and the portion 56 of gradual change in wall thickness and the thick wall portion 55 are located on the radially outer side Dro with respect to the extension line L.Therefore, in the present embodiment, in the support 53, the resistance in the process in which the compressed air Acom passes the side of the support 53 can be suppressed more than in a case where a part of the gradual change in wall thickness portion 56 or a part of the thick wall portion 55 is present on the radially inner side Dri with respect to the extension line L.

[0048] In the present embodiment, since the portion 56 of gradual change of wall thickness is provided between the thick wall portion 55 and the thin wall portion 57, it is possible to suppress stress concentration between the thick wall portion 55 and the thin wall portion 57.

[0049] In the present embodiment, the cooling air Acl can be guided from the outside of the gas turbine casing 14 through the cooling air duct P, which is composed of the outer space P1, the connecting duct P2, the support duct P3, and the inner duct P4, of the turbine rotor shaft 42. Moreover, in the present embodiment, the duct cover 59 in the support space 58 is not disposed in the connecting duct P2, which is a part of the cooling air duct P. Therefore, in the present embodiment, the cooling air Acl flowing in the connecting duct P2 can be used to directly cool a periphery of the connecting duct P2. Therefore, in the present aspect, the outer connecting portion 54o of the support 53 can be efficiently cooled, and a decrease in strength due to a temperature increase of the outer connecting portion 54o of the support 53 can be suppressed. “Second embodiment of intermediate shaft cover”

[0050] A second embodiment of the intermediate shaft cover is described with reference to Fig. 6 described.

[0051] An intermediate shaft cover 50a in the present embodiment is a modified example of the intermediate shaft cover 50 in the first embodiment. The intermediate shaft cover 50a in the present embodiment includes a diffuser 26a, the inner cover 61, the plurality of supports 53, the channel cover 59 provided for each of the plurality of supports 53, and the flange 52, similar to the intermediate shaft cover 50 in the first embodiment. The intermediate shaft cover 50a in the present embodiment further includes an outer cover 51.

[0052] The outer cover 51 includes a tubular outer cover main body 51m centered on the axis Ar, and a cooling air jacket 51j provided on an outer periphery of the outer cover main body 51m, which is a portion of the outer cover main body 51m on the axial downstream side Dad. The annular outer cover main body 51m covers an outer peripheral side of the diffuser 26a. One end of the outer cover 51 on the axial upstream side Dau is attached to the gas turbine casing 14. The cooling air jacket 51j has an annular shape centered on the axis Ar. The cooling air jacket 51j forms the annular outer space P1 together with the outer cover main body 51m on an outer peripheral side of the outer cover main body 51m, which is a portion of the outer cover main body 51m on the axial downstream side Dad.The cooling air line 4 of the cooling air supply device 1 is connected to the cooling air jacket 51j. The cooling air Acl can flow from the cooling air line 4 into the external space P1 at the cooling air jacket 51j.

[0053] The diffuser 26a in the present embodiment includes an outer diffuser 27a and the inner diffuser 28, similar to the diffuser 26 in the first embodiment. The inner diffuser 28 in the present embodiment is the same as the inner diffuser 28 in the first embodiment. On the other hand, the outer diffuser 27a in the present embodiment is different from the outer diffuser 27 in the first embodiment. As described above, the outer cover 51 has the cooling air jacket 51j that forms the outer space P1. Therefore, the outer diffuser 27a in the present embodiment does not have the cooling air jacket 27j of the outer diffuser 27 in the first embodiment. An end of the outer diffuser 27a on the axial downstream side Dad in the present embodiment is in contact with or close to an end of the outer cover 51 on the axial downstream side Dad in the radial direction Dr.

[0054] The flange 52 in the present embodiment is formed in an annular shape centered on the axis Ar, similar to the flange 52 in the first embodiment, and is connected to the annular cooling air jacket 51j centered on the axis Ar. However, the flange 52 in the present embodiment is connected to the cooling air jacket 51j of the outer cover 51.

[0055] The inner cover 61 in the present embodiment has the same configuration as that of the inner cover 61 in the first embodiment and covers an outer periphery of the intermediate rotor shaft 12m. Therefore, similar to the inner cover 61 in the first embodiment, the inner cover 61 in the present embodiment includes the first inner cover 62 centered on the axis Ar and the second inner cover 63 centered on the axis Ar. One end on the axial upstream side Dau of the first inner cover 62 is connected to one end on the axial downstream side Dad of the inner diffuser 28. The second inner cover 63 is arranged on the radially inner side Dri of the first inner cover 62 and is connected to the first inner cover 62.The second inner cover 63 forms together with the first inner cover 62 an annular inner channel P4 extending in the axial direction Da on the radial outer side Dro of the intermediate rotor shaft 12m, which is the radial inner side Dri of the first inner cover 62.

[0056] The plurality of supports 53 in the present embodiment have the same configuration as the plurality of supports 53 in the first embodiment and are arranged in the circumferential direction Dc. Therefore, each of the supports 53 in the present embodiment extends from the outer periphery of the first inner cover 62 to the radially outer side Dro and is connected to the flange 52. Therefore, the plurality of supports 53 are connected to the outer cover 51 through the flange 52.

[0057] Each support 53 in the present embodiment, although in Fig. 6, similar to each stay %§ in the first embodiment, it also has a thick wall portion, a thin wall portion, and a portion of gradual change in wall thickness. In the stay 53 in the present embodiment, a portion on the radially inner side Dri with respect to the extension line L of a generatrix intersecting a virtual plane including the axis Ar on an inner peripheral surface of the outer diffuser 27a is the thin wall portion 53, as in the stay 53 in the first embodiment.

[0058] As in the first embodiment, the support space 58 is formed at each support 53. The support space 58 communicates with the exterior space P1 of the outer cover 51 through the connecting passage P2, which is a part of the cooling air passage P. The connecting passage P2 is formed in the cooling air jacket 51j of the outer cover 51 and the flange 52.

[0059] As in the first embodiment, the duct cover 59 defining the support duct P3, which is a part of the cooling air duct P, is disposed in the support space 58. The duct cover 59 is not disposed in the connecting duct P2. The outer space P1, the connecting duct P2, the support duct P3, and the inner duct P4 communicate with each other to form the cooling air duct P, which is configured to supply the cooling air Acl from the outside of the gas turbine casing 14 to the turbine rotor shaft 42.

[0060] Also in the present embodiment, similar to the first embodiment as described above, in the stay 53, the thick wall portion having a greater thickness in the circumferential direction Dc than the thickness of the thin wall portion is formed in the region including the outer connecting portion indirectly connected to the outer cover 51. Therefore, the strength of the outer connecting portion in the stay 53 can be increased. Further, also in the present embodiment, in the stay 53, a thin wall portion having a smaller thickness in the circumferential direction than the thickness of the thick wall portion is formed in the region including the inner connecting portion connected to the inner cover 61. Therefore, the resistance in the process in which the compressed air Acom is discharged from the diffuser 26a and passes the side of the stay 53 can be suppressed.

[0061] As described above, unlike the first embodiment, the outer cover 51 may be a different component from the outer diffuser 27a. “Third embodiment of intermediate shaft cover”

[0062] A third embodiment of the intermediate shaft cover is described with reference to Fig. 7 described.

[0063] An intermediate shaft cover 50b in the present embodiment is a modified example of the intermediate shaft cover 50a in the second embodiment. The intermediate shaft cover 50b in the present embodiment includes, similarly to the intermediate shaft cover 50a in the second embodiment, the diffuser 26a, an outer cover 51b, the inner cover 61, a plurality of supports 53b, and the flange 52.

[0064] The outer cover 51b in the present embodiment has a tubular shape centered on the axis Ar, similar to the outer cover 51 in the second embodiment. However, the outer cover 51b in the present embodiment does not have the cooling air jacket 51j of the outer cover 51 in the second embodiment.

[0065] The diffuser 26a in the present embodiment has the same outer diffuser 27a and inner diffuser 28 as the diffuser 26a in the second embodiment. The end of the outer diffuser 27a on the axial downstream side Dad in the present embodiment is in contact with or close to an end of the outer cover 51b on the axial downstream side Dad in the radial direction Dr.

[0066] The flange 52 in the present embodiment is formed in an annular shape centered on the axis Ar, similar to the flange 52 in the second embodiment. The flange 52 is connected to the end of the outer cover 51b on the axial downstream side Dad.

[0067] The inner cover 61 in the present embodiment has the same configuration as that of the inner cover 61 in the first embodiment and covers an outer periphery of the intermediate rotor shaft 12m. Therefore, similar to the inner cover 61 in the second embodiment, the inner cover 61 in the present embodiment includes the first inner cover 62 centered on the axis Ar and the second inner cover 63 centered on the axis Ar. One end on the axial upstream side Dau of the first inner cover 62 is connected to one end on the axial downstream side Dad of the inner diffuser 28. The second inner cover 63 is arranged on the radially inner side Dri of the first inner cover 62 and is connected to the first inner cover 62.The second inner cover 63 forms together with the first inner cover 62 an annular inner channel P4 extending in the axial direction Da on the radial outer side Dro of the intermediate rotor shaft 12m, which is the radial inner side Dri of the first inner cover 62.

[0068] The plurality of supports 53b in the present embodiment are arranged in the circumferential direction Dc, similar to the plurality of supports 53 in the second embodiment. Therefore, each of the supports 53b in the present embodiment extends from the outer periphery of the first inner cover 62 to the radially outer side Dro and is connected to the flange 52. Therefore, the plurality of supports 53b are connected to the outer cover 51b through the flange 52.

[0069] Each support 53b in the present embodiment, although in Fig. 7, similar to each stay 53 in the first embodiment, the stay 53b also has a thick wall portion, a thin wall portion, and a wall thickness gradual change portion. In the stay 53b in the present embodiment, a portion on the radially inner side Dri with respect to the extension line L of a generatrix intersecting a virtual plane including the axis Ar on an inner peripheral surface of the outer diffuser 27a is the thin wall portion, as in the stay 53 in the first embodiment.

[0070] Unlike the support 53 in each of the above embodiments, the support space 58 is not formed in the support 53b in the present embodiment. Therefore, the intermediate shaft cover 50b in the present embodiment does not have the channel cover 59 in the first embodiment and the second embodiment.

[0071] A cooling air duct 4b of the cooling air supply device 1 is connected to the first inner cover 62. Therefore, in the present 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 the supports 53 and 53b. That is, a cooling air passage Pb of the intermediate shaft cover 50b in the present embodiment is constructed only from the inner passage P4 of the inner cover 61.

[0072] Also in the present embodiment, similar to the first embodiment and the second embodiment as described above, in the stay 53b, the thick wall portion having a greater thickness in the circumferential direction Dc than the thickness of the thin wall portion is formed in the region including the outer connecting portion indirectly connected to the outer cover 51b. Therefore, the strength of the outer connecting portion in the stay 53b can be increased. Further, also in the present embodiment, in the stay 53b, a thin wall portion having a smaller thickness in the circumferential direction than the thickness of the thick wall portion is formed in the region including the inner connecting portion connected to the inner cover 61. Therefore, the resistance in the process in which the compressed air Acom is discharged from the diffuser 26a and passes the side of the stay 53b can be suppressed.

[0073] As described above, the cooling air Acl can be directly supplied from the cooling air supply device 1 to the inner duct P4 of the inner cover 61 without forming the external space P1 at the outer cover 51b and without forming the support space 58 at the plurality of supports 53b. Note that the present embodiment is a modified example of the second embodiment. However, even in the first embodiment, the cooling air Acl can be directly supplied from the cooling air supply device 1 to the inner duct P4 of the inner cover 61 without forming the external space P1 at the outer diffuser 27 which is the outer cover and without forming the support space 58 at the plurality of supports 53b. “Fourth embodiment of intermediate shaft cover”

[0074] A fourth embodiment of the intermediate shaft cover is described with reference to Fig. 8 described.

[0075] An intermediate shaft cover 50c in the present embodiment is a modified example of the intermediate shaft cover 50 in the first embodiment. The intermediate shaft cover 50c in the present embodiment is the same as the intermediate shaft cover 50 in the first embodiment, except that the flange 52 of the intermediate shaft cover 50 in the first embodiment is not provided.

[0076] The plurality of supports 53 in the present embodiment 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 the present embodiment does not have a flange 52.

[0077] The present embodiment is a modified example of the first embodiment. However, in the second embodiment and also the third embodiment, the flange 52 may be omitted, and the plurality of supports 53 and 53b may be directly connected to the outer covers 51 and 51b. That is, the plurality of supports 53 and 53b may be directly connected to an annular member such as a part of the outer diffuser 27, a part of the outer covers 51 and 51b, and the flange 52. In this case, the annular member must be disposed on the outer peripheral side of the diffuser space S at the end of the outer diffuser on the axial downstream side Dad. Moreover, the annular member must be provided so as not to be able to move relative to the gas turbine casing 14.

[0078] Furthermore, the present disclosure is not limited to each of the embodiments described above. Various additions, modifications, replacements, partial deletions, and the like may be made without departing from the conceptual idea and gist of the present invention, which are derived from the contents defined in the claims and their equivalents. “Supplementary Notes”

[0079] The intermediate shaft covers 50, 50a, 50b and 50c in each of the above-described embodiments are understood, for example, as follows.

[0080] (1) An intermediate shaft cover according to a first aspect is applied to a gas turbine 10 described below.

[0081] The gas turbine 10 includes a gas turbine rotor 11 rotatable about an axis Ar, and a gas turbine casing 14 covering an outer periphery of the gas turbine rotor 11. The gas turbine rotor 11 includes a gas turbine rotor shaft 12 extending in an axial direction Da, a plurality of compressor rotor blade rows 23 provided in a portion of the gas turbine rotor shaft 12 on an axial upstream side Dau among the axial upstream side Dau and an axial downstream side Dad in the axial direction Da, and a plurality of turbine rotor blade rows 43 provided in a portion of the gas turbine rotor shaft 12 on the axial downstream side Dad with a distance from the plurality of compressor rotor blade rows 23 to the axial downstream side Dad.

[0082] Intermediate shaft covers 50, 50a, 50b and 50c include diffusers 26 and 26a through which compressed air Acom, which has passed through the plurality of compressor rotor blade rows 23, can flow and which form an annular diffuser space S centered on the axis Ar, a tubular inner cover 61 covering an intermediate rotor shaft 12m between the plurality of compressor rotor blade rows 23 and the plurality of turbine rotor blade rows 43 at the gas turbine rotor shaft 12, on the axial downstream side Dad with respect to the diffusers 26 and 26a, annular outer covers 27, 51 and 51b covering an outer peripheral side of the diffuser space S and connected to the gas turbine casing 14, and supports 53 and 53b extending from an outer periphery of the inner cover 61 extend to a radial outer side Dro with respect to the axis Ar and which are directly or indirectly connected to the outer covers 27, 51 and 51b.The supports 53 and 53b include a thick wall portion 55 having a large thickness in a circumferential direction Dc with respect to the axis Ar, and a thin wall portion 57 having a smaller thickness in the circumferential direction Dc than the thickness of the thick wall portion 55. The thick wall portion 55 is formed in a region including an outer connecting portion 54o having one end on the radially outer side Dro and which is directly or indirectly connected to the outer covers 27, 51, and 51b, at the supports 53 and 53b. The thin wall portion 57 is formed in a region including an inner connecting portion 54i having one end on a radially inner side Dri with respect to the axis Ar and which is connected to the inner cover 61, at the supports 53 and 53b.

[0083] In the present aspect, in the supports 53 and 53b, the thick wall portion 55 having a greater thickness in the circumferential direction Dc than the thickness of the thin wall portion 57 is formed in the region including the outer connecting portion 54o connected to the outer covers 27, 51, and 51b directly or indirectly. Therefore, the strength of the outer connecting portion 54o in the supports 53 and 53b can be increased. Furthermore, in the present aspect, in the supports 53 and 53b, the thin wall portion 57 having a smaller thickness in the circumferential direction Dc than the thickness of the thick wall portion 55 is formed in the region including the inner connecting portion 54i connected to the inner cover 61. Therefore, it is possible to suppress narrowing of a width of a flow path of the compressed air Acom discharged from the diffusers 26 and 26a and passing one side of the supports 53 and 53b.Therefore, in the present aspect, it is possible to suppress resistance in a process in which the compressed air Acom passes the side of the supports 53 and 53b.

[0084] (2) In an intermediate shaft cover according to a second aspect, In the intermediate shaft covers 50, 50a, 50b and 50c according to the first aspect, the supports 53 and 53b include a wall thickness gradual change portion 56, in which the thickness gradually decreases in the circumferential direction Dc from the thick wall portion 55 to the thin wall portion 57, between the thick wall portion 55 and the thin wall portion 57.

[0085] In the present aspect, since the portion 56 of gradual change of wall thickness is present between the thick wall portion 55 and the thin wall portion 57, it is possible to suppress stress concentration between the thick wall portion 55 and the thin wall portion 57.

[0086] (3) In an intermediate shaft cover according to a third aspect, In the intermediate shaft covers 50, 50a, 50b and 50c according to the first aspect or the second aspect, the diffusers 26 and 26a include outer diffusers 27 and 27a defining an outer peripheral edge of the diffuser space S, and an inner diffuser 28 defining an inner peripheral edge of the diffuser space S.

[0087] The outer diffusers 27 and 27a are formed such that an inner diameter gradually increases toward the axial downstream side Dad. In the supports 53 and 53b, a portion on the radially inner side Dri with respect to an extension line L of a generatrix intersecting a virtual plane containing the axis Ar on an inner peripheral surface of the outer diffusers 27 and 27a is the thin wall portion 57.

[0088] In the present aspect, most of the compressed air Acom discharged from the diffusers 26 and 26a and passing the side of the supports 53 and 53b flows through the radially inner side Dri with respect to the extension line L of the generatrix on the inner peripheral surface of the outer diffusers 27 and 27a. Therefore, in the present aspect, it is possible to suppress resistance in a process in which the compressed air Acom passes the side of the supports 53 and 53b.

[0089] (4) In an intermediate shaft cover according to a fourth aspect, In the intermediate shaft cover 50 according to any one of the first aspect to the third aspect, the diffuser 26 includes an outer diffuser 27 defining an outer peripheral edge of the diffuser space S and an inner diffuser 28 defining an inner peripheral edge of the diffuser space S.

[0090] The outer cover 27 is the outer diffuser.

[0091] The outer covers 27, 51 and 51b may be different components from the outer diffusers 27 and 27a, but may be the outer diffuser 27 as in the present aspect.

[0092] (5) In an intermediate shaft cover according to a fifth aspect, In the intermediate shaft covers 50, 50a and 50c according to any one of the first to fourth aspects, there is further provided a duct cover 59 defining a support duct P3 that is a part of a cooling air duct P configured to supply cooling air Acl from an outside of the gas turbine casing 14 to a turbine rotor shaft 42 in which the plurality of turbine rotor blade rows 43 are provided in the gas turbine rotor shaft 12.

[0093] The outer covers 27 and 51 contain an outer space P1 into which the cooling air Acl can flow from the outside of the gas turbine casing 14, as a part of the cooling air duct P.

[0094] The support 53 includes a support space 58 that communicates with the external space P1. The duct cover 59 is disposed in the support space 58. The external space P1 at the outer covers 27 and 51 and the support duct P3 at the duct cover 59 are connected by a connecting duct P2 that is a part of the cooling air duct P. The duct cover 59 is not disposed in the connecting duct P2. The inner cover 61 includes an internal duct P4 that is capable of communicating with the support duct P3 and is configured to supply the cooling air Acl from the support duct P3 to the turbine rotor shaft 42 as a part of the cooling air duct P.

[0095] In the present aspect, the cooling air Acl can be guided from the outside of the gas turbine casing 14 through the cooling air duct P, which is composed of the outer space P1, the connecting duct P2, the support duct P3, and the inner duct P4, of the turbine rotor shaft 42. Furthermore, in the present aspect, the duct cover 59 in the support space 58 is not disposed in the connecting duct P2, which is a part of the cooling air duct P. Therefore, in the present aspect, the cooling air Acl flowing in the connecting duct P2 can be used to directly cool a periphery of the connecting duct P2. Therefore, in the present aspect, the outer connecting portion 54o of the support 53 can be efficiently cooled, and a decrease in strength due to a temperature increase of the outer connecting portion 54o of the support 53 can be suppressed.

[0096] (6) In an intermediate shaft cover according to a sixth aspect, In the intermediate shaft covers 50, 50a and 50b according to any one of the first to fifth aspects, a flange 52 is further provided which forms an annular shape centered on the axis Ar and which is connected to the outer covers 27, 51 and 51b.

[0097] The supports 53 and 53b are connected to the flange 52.

[0098] The end of the supports 53 and 53b on the radial outer side Dro may be connected directly to the outer covers 27, 51 and 51b, but may, as in the present aspect, be connected to the outer covers 27, 51 and 51b by the flange 52.

[0099] For example, the gas turbine 10 in each of the embodiments described above is understood as follows.

[0100] (7) In a gas turbine according to a seventh aspect, the intermediate shaft covers 50, 50a, 50b and 50c according to any one of the first aspect to the sixth aspect, the gas turbine rotor 11, the gas turbine casing 14 and a combustor 30 which is attached to the gas turbine casing 14 and which generates combustion gas G by burning fuel F in compressed air Acom which has flowed into the diffuser space S are provided.

[0101] The combustion chamber 30 is formed such that the combustion gas G is guided to the plurality of turbine rotor blade rows 43. Industrial applicability

[0102] According to one aspect of the present disclosure, it is possible to suppress resistance to air flow from a compressor while increasing the strength of a support of a gas turbine. It is possible to reduce operating costs during liquefaction and evaporation of a gas. List of reference symbols 1 cooling air supply device 2 vent line 3 coolers 4, 4b Cooling air line 5 Gain compressor 9 Generator 10 gas turbines 11 Gas turbine rotor 12 Gas turbine rotor shaft 12m intermediate rotor shaft 14 Gas turbine casing 15 intermediate housing 16 Outlet housing 20 Compressor 21 Compressor rotor 22 Compressor rotor shaft 23 compressor rotor blade rows 24 Compressor housing 25 compressor stator blade rows 26, 26a Diffuser 27, 27a Outer diffuser 27m outer diffuser main body 27j cooling air jacket 28 inner diffuser 30 combustion chamber 31 burners 32 combustion cylinders (or transition piece) 40 turbines 41 Turbine rotor 42 Turbine rotor shaft 42p cooling air duct 43 Turbine rotor blade row 43b Rotor blade 43p cooling air duct 44 Turbine housing 45 Turbine stator blade row 49 Combustion gas duct 50, 50a, 50b, 50c intermediate shaft cover 51, 51b Outer cover 51m outer cover main body 51j cooling air jacket 52 flange 53,53b Support 54o outer connecting section 54i inner connecting section 55 thick wall section 56 Section of gradual change of wall thickness 57 thin wall section 58 column space 59 Channel cover 61 inner cover 62 first inner cover 63 second inner cover P, Pb air cooling channel P1 Outdoor Space P2 connecting channel P3 support channel P4 inner channel S Diffuser room A Air Acom compressed air Acl cooling air F Fuel G Combustion gas EC exhaust Ar axis Since axial direction Dau axial upstream side The axial downstream side Dc circumferential direction Dr radial direction Dri radial inside Dro radial outside L extension line QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-160173

[0002] WO 2018 / 181902

[0008]

Claims

An intermediate shaft cover of a gas turbine, including: a gas turbine rotor rotatable about an axis, and a gas turbine casing covering an outer periphery of the gas turbine rotor, wherein the gas turbine rotor includes: a gas turbine rotor shaft extending in an axial direction, a plurality of compressor rotor blade rows provided in a portion of the gas turbine rotor shaft on an axial upstream side among the axial upstream side and an axial downstream side in the axial direction, and a plurality of turbine rotor blade rows provided in a portion of the gas turbine rotor shaft on the axial downstream side at a distance from the plurality of compressor rotor blade rows to the axial downstream side, the intermediate shaft cover comprising: a diffuser through which compressed air that has passed through the plurality of compressor rotor blade rows can flow and which has an annular diffuser space centered on the axis is,forms; a tubular inner cover covering an intermediate rotor shaft between the plurality of compressor rotor blade rows and the plurality of turbine rotor blade rows at the gas turbine rotor shaft, on the axial downstream side with respect to the diffuser; an annular outer cover covering an outer peripheral side of the diffuser space and connected to the gas turbine casing; and a support extending from an outer periphery of the inner cover to a radial outer side with respect to the axis and directly or indirectly connected to the outer cover, wherein the support includes a thick wall portion having a large thickness in a circumferential direction with respect to the axis and a thin wall portion having a smaller thickness in the circumferential direction than the thickness of the thick wall portion, the thick wall portion in a region forming an outer connecting portion,which has an end on the radially outer side and which is connected directly or indirectly to the outer cover, is formed in the support, and the thin wall portion is formed in a region which has an inner connecting portion which has an end on a radially inner side with respect to the axis and which is connected to the inner cover, is formed in the support. The intermediate shaft cover according to claim 1, wherein the stay includes a wall thickness gradual change portion, in which the thickness gradually decreases in the circumferential direction from the thick wall portion to the thin wall portion, between the thick wall portion and the thin wall portion. The intermediate shaft cover according to claim 1 or 2, wherein the diffuser includes 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 outer diffuser is formed such that an inner diameter gradually increases toward the axial downstream side, and in the support, a portion on the radially inner side with respect to an extension line of a generatrix intersecting a virtual plane including the axis on an inner peripheral surface of the outer diffuser is the thin wall portion. The intermediate shaft cover according to claim 1 or 2, wherein the diffuser includes 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, and the outer cover is the outer diffuser. The intermediate shaft cover according to claim 1 or 2, further comprising: a duct cover defining a support duct that is a part of a cooling air duct configured to supply cooling air from an outside of the gas turbine casing to a turbine rotor shaft in which the plurality of turbine rotor blade rows are provided at the gas turbine rotor shaft, wherein the outer cover includes an outside space into which the cooling air can flow from the outside of the gas turbine casing, as a part of the cooling air duct, the support includes a support space that communicates with the outside space, the duct cover is disposed in the support space, the outside space at the outer cover and the support duct at the duct cover are connected by a connecting duct that is a part of the cooling air duct, the duct cover is not disposed in the connecting duct, and the inner cover includes an inner duct that is capable of communicating with the support duct,and is configured to supply the cooling air from the support duct to the turbine rotor shaft, as part of the cooling air duct., The intermediate shaft cover according to claim 1 or 2, further comprising:a flange forming an annular shape centered on the axis and connected to the outer cover,wherein the support is connected to the flange. A gas turbine comprising: the intermediate shaft cover according to claim 1 or 2; the gas turbine rotor; the gas turbine casing; and a combustor attached to the gas turbine casing and generating combustion gas by burning fuel in compressed air that has flowed into the diffuser space, the combustor being configured to supply the combustion gas to the plurality of turbine rotor blade rows.

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