Shaft seal assembly and steam turbine

Abstract

To reduce a size of a shaft seal assembly in a steam turbine.SOLUTION: A shaft seal assembly includes: a seal ring disposed opposing to a portion on an axial downstream side of a final moving blade row and on an axial upstream side of a bearing device in a rotor shaft; a seal holding ring that supports the seal ring; a bellows device that forms a cylindrical shape around an axis, extends axially, and has an end on the axial downstream side connected to the seal holding ring; an outer peripheral side partition member that can connect the end on the axial upstream side of the bellows device and an exhaust casing or an inner diffuser; and a weight insertion pipe through which a balance weight attachable to the rotor shaft can be inserted. The outer peripheral side partition member includes a conical part. The weight insertion pipe is connected to the conical part so that a pipe central axis of the weight insertion pipe is disposed along a bus line on an outer peripheral surface of the conical part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a shaft seal assembly and a steam turbine including the shaft seal assembly.

Background Art

[0002] Many steam turbines include a rotor, a turbine casing, a diffuser, an exhaust casing, a bearing device, and a shaft seal assembly.

[0003] The rotor has a rotor shaft rotatable about an axis, and a plurality of moving blade rows attached to the rotor shaft in an axial direction in which the axis extends. The turbine casing covers the outer peripheral side of the plurality of moving blade rows. The diffuser is disposed on the downstream side of the axis with respect to the final moving blade row, which is the moving blade row on the most downstream side in the axial direction among the plurality of moving blade rows, among the plurality of moving blade rows. The diffuser defines a diffuser space through which the steam that has passed through the final moving blade row passes and gradually expands radially outward with respect to the axis as it moves toward the downstream side of the axis. The diffuser has an outer diffuser that defines the radially outer edge of the diffuser space and an inner diffuser that defines the radially inner edge of the diffuser space with respect to the axis. The exhaust casing has an exhaust port 31 that opens radially outward and defines an exhaust space that can guide the steam that has passed through the diffuser space to the exhaust port 31. The bearing device rotatably supports the rotor and supports a portion of the rotor shaft on the downstream side of the axis with respect to the final moving blade row. The bearing device has a bearing disposed opposite to the surface of the rotor shaft and a bearing box that supports and covers the bearing. The shaft seal assembly is disposed opposite to a portion of the rotor shaft on the downstream side of the axis with respect to the final moving blade row and on the upstream side of the axis with respect to the bearing device, and suppresses the steam from flowing from the upstream side of its own axis to the downstream side of its own axis.

[0004] The following Patent Document 1 discloses the shaft seal assembly of the steam turbine described above. This shaft seal assembly has a plurality of seal rings, a seal holding ring, a bellows device, an outer peripheral side partitioning member, a weight insertion tube, and a bearing side connecting member.

[0005] The plurality of seal rings are all annular about the axis and are arranged opposite to the outer peripheral surface of the rotor shaft. The seal retaining ring is arranged around the plurality of seal rings and supports the plurality of seal rings. The bellows device is cylindrical about the axis and extends in the axial direction and is axially expandable and contractible. The end on the downstream side of the axis of this bellows device is connected to the seal retaining ring.

[0006] The outer peripheral side partition member connects the bellows device and the inner diffuser. This outer peripheral side partition member partitions the space between the outer peripheral side of the bellows device and the inner peripheral side of the inner diffuser into an upstream space and a downstream space with respect to the axis. This outer peripheral side partition member has a bellows side connection portion, a disk portion, a conical portion, and a casing side connection flange. The bellows side connection portion is annular about the axis and is connected to the end on the downstream side of the axis of the bellows device. The disk portion is an annular flat plate perpendicular to the axis about the axis. This disk portion is connected to the radially outer end of the bellows side connection portion. The conical portion has an outer peripheral surface and an inner peripheral surface. The outer peripheral surface forms a conical surface about the axis such that the outer diameter gradually increases as it goes toward the downstream side of the axis. The inner peripheral surface forms a conical surface about the axis such that the inner diameter gradually increases as it goes toward the downstream side of the axis. The upstream end of the axis of this conical portion is connected to the radially outer edge of the disk portion. The casing side connection flange is annular about the axis and is connected to the end on the downstream side of the axis of the conical portion and is connected to the inner diffuser.

[0007] The weight insertion tube is capable of inserting a balance weight attachable to the rotor shaft. The weight insertion tube is provided in this disk portion such that the central axis of the tube of this weight insertion tube is inclined with respect to the axis and intersects the direction in which the disk portion expands.

[0008] The bearing-side connecting member connects the seal retaining ring and the bearing device. This bearing-side connecting member has a retaining-ring-side connecting flange, a body extending in the axial direction, and a bearing-side connecting flange. The retaining-ring-side connecting flange is provided at the upstream end of the body in the axial direction. The bearing-side connecting flange is provided at the downstream end of the body in the axial direction. It is considered that the bearing-side connecting member is connected to the seal retaining ring by a connecting bolt inserted through the retaining-ring-side flange of this bearing-side connecting member. Also, it is considered that the bearing-side connecting member is connected to the bearing device by a connecting bolt inserted through the bearing-side connecting flange of this bearing-side connecting member.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] In a steam turbine, improving the exhaust efficiency of steam leads to an improvement in the performance of the steam turbine. For this reason, it is required to increase the degree of freedom in the design of the diffuser and the exhaust casing through which the steam that has passed through the last moving blade row flows. One way to increase the degree of freedom in the design of the diffuser and the exhaust casing is to miniaturize the shaft seal assembly.

[0011] Therefore, an object of the present disclosure is to provide a shaft seal assembly that can be miniaturized and a steam turbine including this shaft seal assembly.

Means for Solving the Problems

[0012] A shaft seal assembly according to one aspect of the disclosure for achieving the above object is targeted at the following steam turbine. This steam turbine includes a turbine rotor having a rotor shaft rotatable about an axis and a plurality of moving blade rows attached to the rotor shaft in an axial direction along which the axis extends, a turbine casing covering an outer peripheral side of the plurality of moving blade rows, and among the plurality of moving blade rows, a diffuser disposed downstream of the axis from a final moving blade row which is the moving blade row on the most downstream side of the axis between an upstream side and a downstream side of the axis in the axial direction, through which steam passing through the final moving blade row passes, and defining a diffuser space that gradually expands radially outward with respect to the axis as it goes downstream of the axis, an exhaust casing having an exhaust port opening radially outward and defining an exhaust space capable of guiding the steam passing through the diffuser space to the exhaust port, and a bearing device rotatably supporting the turbine rotor and supporting a portion of the rotor shaft downstream of the axis from the final moving blade row within the rotor shaft. The diffuser has an outer diffuser whose cross section perpendicular to the axis forms an annular shape and gradually expands radially outward as it goes downstream of the axis, defining an outer edge of the diffuser space in the radial direction, and an inner diffuser whose cross section perpendicular to the axis forms an annular shape and gradually expands radially outward as it goes downstream of the axis, defining an inner edge of the diffuser space in the radial direction with respect to the axis. The bearing device has a bearing disposed opposite to a surface of the rotor shaft and a bearing housing supporting and covering the bearing. The shaft seal assembly is annular about the axis, and is disposed opposite to a portion of the rotor shaft that is downstream of the axis from the last moving blade row and upstream of the axis from the bearing device, and can suppress the steam flowing from the upstream side of its own axis to the downstream side of its own axis. A seal ring, a seal retaining ring having an annular cross-section perpendicular to the axis and disposed around the annular seal ring to support the seal ring, a bellows device having a cylindrical shape about the axis and extending in the axial direction, being axially expandable and contractible, and having an end on the downstream side of the axis connected to the seal retaining ring, and an outer peripheral side partition member capable of connecting the end on the upstream side of the axis of the bellows device to the exhaust casing or the inner diffuser, and a weight insertion pipe through which a balance weight attachable to the rotor shaft can be inserted. The outer peripheral side partition member is annular about the axis, is located downstream of the axis from the end on the upstream side of the axis of the bellows device and radially outside the bellows device, and has a casing side connection flange connectable to the exhaust casing or the inner diffuser, and a conical portion connecting the casing side connection flange and the end on the upstream side of the axis of the bellows device. The conical portion has an outer peripheral surface and an inner peripheral surface. The outer peripheral surface forms a conical surface about the axis such that the outer diameter gradually increases toward the downstream side of the axis. The inner peripheral surface forms a conical surface about the axis such that the inner diameter gradually increases toward the downstream side of the axis. The end on the upstream side of the axis of the conical portion is connected to the end on the upstream side of the axis of the bellows device, and the end on the downstream side of the axis of the conical portion is connected to the casing side connection flange. The weight insertion pipe is connected to the conical portion such that the central axis of the pipe of the weight insertion pipe is along the generatrix on the outer peripheral surface of the conical portion, and at least a part of one side in the radial direction with respect to the central axis of the pipe is exposed to the outer peripheral side from the outer peripheral surface, and at least a part of the other side in the radial direction with respect to the central axis of the pipe is exposed to the inner peripheral side from the inner peripheral surface.

[0013] Here, a shaft seal assembly as a comparative example will be described. This shaft seal assembly includes a seal ring, a seal retaining ring, a bellows device, an outer peripheral side partitioning member, and a weight insertion tube.

[0014] The seal ring is annular about the axis, similar to the seal ring of this embodiment, and is disposed opposite to the outer peripheral surface of the rotor shaft. The seal retaining ring is disposed around the seal ring and supports the seal ring. The bellows device is cylindrical about the axis and extends in the axial direction. The end on the downstream side of the axis of this bellows device is connected to the seal retaining ring.

[0015] The outer peripheral side partitioning member connects the bellows device and the inner diffuser. This outer peripheral side partitioning member partitions the space between the outer peripheral side of the bellows device and the inner peripheral side of the inner diffuser into an upstream space and a downstream space with respect to the axis. This outer peripheral side partitioning member has a bellows side connection portion, a disk portion, a conical portion, and a casing side connection flange. The bellows side connection portion is annular about the axis and is connected to the end on the downstream side of the axis of the bellows device. The disk portion is an annular plate perpendicular to the axis about the axis. This disk portion is connected to the radially outer end of the bellows side connection portion. The conical portion has an outer peripheral surface and an inner peripheral surface, similar to the conical portion of this embodiment. The outer peripheral surface and the inner peripheral surface form a conical surface about the axis, similar to the outer peripheral surface and the inner peripheral surface of the conical portion in this embodiment. The end on the upstream side of the axis of this conical portion is connected to the radially outer edge of the disk portion. The casing side connection flange is annular about the axis, is connected to the end on the downstream side of the axis of the conical portion, and is connected to the inner diffuser.

[0016] The weight insertion tube is capable of inserting a balance weight attachable to the rotor shaft. The weight insertion tube is provided in this disk portion such that the central axis of the tube of this weight insertion tube is inclined with respect to the axis and intersects the direction in which the disk portion spreads.

[0017] That is, the shaft seal assembly in this comparative example is the shaft seal assembly described in the background art section.

[0018] In the shaft seal assembly according to this aspect, since the weight insertion pipe is provided in the conical portion, the disk portion in the shaft seal assembly in the comparative example becomes unnecessary, and this disk portion can be omitted. Therefore, in the shaft seal assembly according to this aspect, the size in the radial direction can be made smaller than that in the comparative example.

[0019] In the comparative example, the weight insertion pipe is provided in the disk portion which is a flat plate. On the other hand, in this aspect, the weight insertion pipe is provided in the conical portion which has higher rigidity than the flat plate. Also, in the weight insertion pipe in the comparative example, this weight insertion pipe is provided in this disk portion so that the central axis of the pipe intersects with the direction in which the disk portion which is a flat plate spreads. On the other hand, the weight insertion pipe in this aspect is provided in the conical portion so that the central axis of this weight insertion pipe is along the generatrix on the outer peripheral surface of the conical portion. For this reason, in this aspect, the connection portion between the weight insertion pipe and the installation object can be made longer than in the comparative example. Therefore, in this aspect, the direction in which the central axis of the pipe extends can be made more stable than in the comparative example. For this reason, in this aspect, the balance weight can be more easily accessed to the target position via the weight insertion pipe than in the comparative example.

[0020] A steam turbine according to one aspect of the disclosure for achieving the above object, includes the shaft seal assembly of the above aspect, the turbine rotor, the turbine casing, the diffuser, the exhaust casing, and the bearing device.

Effect of the Invention

[0021] According to one aspect of the present disclosure, the size reduction of the shaft seal assembly can be achieved.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of a steam turbine in the present disclosure will be described in detail with reference to the drawings.

[0024] As shown in FIG. 1, the steam turbine in the present embodiment is a two-flow exhaust type steam turbine. Therefore, this steam turbine includes a first steam turbine section 10a and a second steam turbine section 10b. Both the first steam turbine section 10a and the second steam turbine section 10b include a turbine rotor 11 that rotates about an axis Ar, a casing 20 that covers the turbine rotor 11, a plurality of stationary blade rows 17 fixed to the casing 20, a steam inlet pipe 19, a bearing device 50, and a shaft seal assembly 60. Hereinafter, the circumferential direction around the axis Ar will be simply referred to as the circumferential direction Dc, and the radial direction with respect to the axis Ar will be referred to as the radial direction Dr. Further, the side approaching the axis Ar in the radial direction Dr is the inner radial side Dri, and the opposite side is the outer radial side Dro.

[0025] The first steam turbine section 10a and the second steam turbine section 10b share a steam inlet pipe 19. In the first steam turbine section 10a, the components excluding this steam inlet pipe 19 are arranged on one side of the axial direction Da with respect to this steam inlet pipe 19. Also, in the second steam turbine section 10b, the components excluding this steam inlet pipe 19 are arranged on the other side of the axial direction Da with respect to this steam inlet pipe 19. In each of the steam turbine sections 10a and 10b, the side approaching the steam inlet pipe 19 in the aforementioned axial direction Da is defined as the axial upstream side Dau, and the opposite side is defined as the axial downstream side Dad.

[0026] The configuration of the first steam turbine section 10a and the configuration of the second steam turbine section 10b are basically the same. Therefore, hereinafter, the first steam turbine section 10a will be mainly described.

[0027] The turbine rotor 11 has a rotor shaft 12 extending in the axial direction Da around the axis Ar, and a plurality of moving blade rows 13 attached to this rotor shaft 12. The plurality of moving blade rows 13 are arranged in the axial direction Da. Each moving blade row 13 is composed of a plurality of moving blades arranged in the circumferential direction Dc. The turbine rotor 11 of the first steam turbine section 10a and the turbine rotor 11 of the second steam turbine section 10b are located on the same axis Ar and are connected to each other.

[0028] The casing 20 has a turbine casing 21 and an exhaust chamber 25. The turbine casing 21 forms a substantially conical space around the axis Ar and covers the outer periphery of the turbine rotor 11. The plurality of moving blade rows 13 of the turbine rotor 11 are arranged in this conical space. A plurality of stationary blade rows 17 are arranged in the axial direction Da in this conical space. Each of the plurality of stationary blade rows 17 is arranged on the axial upstream side Dau of one of the plurality of moving blade rows 13 of the plurality of moving blade rows 13. The plurality of stationary blade rows 17 are fixed to the turbine casing 21. The plurality of stationary blade rows 17 are each composed of a plurality of stationary blades arranged in the circumferential direction Dc.

[0029] As shown in FIG. 2, the exhaust chamber 25 has a diffuser 26 and an exhaust casing 30.

[0030] The diffuser 26 forms an annular shape with respect to the axis Ar and defines a diffuser space 26s that gradually extends radially outward toward the downstream side Dad of the axis. The steam flowing out from the last moving blade row 13a of the turbine rotor 11 flows into the diffuser space 26s. Here, the last moving blade row 13a is the moving blade row 13 arranged on the most downstream side Dad of the axis among the plurality of moving blade rows 13. The diffuser 26 has an outer diffuser (or steam guide, flow guide) 27 that defines the edge of the radially outer side Dro of the diffuser space 26s and an inner diffuser (or bearing cone) 29 that defines the edge of the radially inner side Dri of the diffuser space 26s. The outer diffuser 27 has an annular cross-section perpendicular to the axis Ar and gradually expands radially outward toward the downstream side Dad of the axis. The inner diffuser 29 also has an annular cross-section perpendicular to the axis Ar and gradually expands radially outward toward the downstream side Dad of the axis. The outer diffuser 27 is connected to the turbine casing 21.

[0031] The exhaust casing 30 has an exhaust port 31. This exhaust port 31 opens radially outward from the inside and vertically downward. A condenser Co for returning steam to water is connected to this exhaust port 31. Therefore, the steam turbine of this embodiment is a downward exhaust type condensing steam turbine. Here, in the orthogonal direction perpendicular to the axis Ar, the non-exhaust side Dpu and the exhaust side Dpe are defined on opposite sides with respect to the axis Ar. Since the steam turbine of this embodiment is a downward exhaust type condensing steam turbine as described above, the exhaust side Dpe is the vertically lower side, and the non-exhaust side Dpu is the vertically upper side.

[0032] The exhaust casing 30 defines an exhaust space 30s that communicates with the diffuser 26. This exhaust space 30s extends circumferentially Dc with respect to the axis Ar around the outer periphery of the diffuser 26, guiding the steam flowing in from the diffuser space 26s to the exhaust port 31. The exhaust casing 30 has a casing downstream end plate 32, a casing upstream end plate 34, and a casing outer peripheral plate 36.

[0033] The casing downstream end plate 32 defines the edge of the axis downstream side Dad of the exhaust space 30s. This casing downstream end plate 32 extends in a direction including a component in the radial direction Dr and in the circumferential direction Dc, and is substantially perpendicular to the axis Ar. In the casing downstream end plate 32, the portion above the axis Ar forms a substantially semi-circular shape. On the other hand, in the casing downstream end plate 32, the portion below the axis Ar forms a substantially rectangular shape. However, a circular opening centered on the axis Ar is formed in this casing downstream end plate 32. The edge of this circular opening forms the radially inner edge Dri of the casing downstream end plate 32. The lower edge of this casing downstream end plate 32 forms a part of the edge of the exhaust port 31.

[0034] The casing outer peripheral plate 36 defines the edge of the radially outer side Dro of the exhaust space 30s. This casing outer peripheral plate 36 is connected to the radially outer edge Dro of the casing downstream end plate 32, extends in the axial direction Da, and extends circumferentially Dc around the axis Ar. The upper side of this casing outer peripheral plate 36 has a semi-cylindrical shape like a kamaboko. The edge of the axis downstream side Dad of this casing outer peripheral plate 36 is connected to the casing downstream end plate 32. Also, the lower edge of this casing outer peripheral plate 36 forms a part of the edge of the exhaust port 31.

[0035] The upstream end plate 34 of the casing defines the edge of the upstream side Dau of the exhaust space 30s along the axis. The upstream end plate 34 of the casing is arranged on the upstream side Dau of the axis relative to the diffuser 26. This upstream end plate 34 of the casing extends radially outward Dro from the outer peripheral surface of the turbine casing 21. This upstream end plate 34 of the casing is substantially perpendicular to the axis Ar. Therefore, this upstream end plate 34 of the casing faces the downstream end plate 32 of the casing with a spacing in the axial direction Da. The lower edge of the upstream end plate 34 of the casing forms a part of the edge of the exhaust port 31. Among the radially outer Dro edges of this upstream end plate 34 of the casing, the part excluding the part forming the edge of the exhaust port 31 is connected to the outer peripheral plate 36 of the casing.

[0036] The exhaust casing 30 of the first steam turbine section 10a and the exhaust casing 30 of the second steam turbine section 10b are connected to each other and integrated.

[0037] The exhaust casing 30 further has an auxiliary exhaust frame 40. As shown in FIGS. 2 and 3, this auxiliary exhaust frame 40 includes a part of the region that is radially inner Dri and downstream Dad of the axis relative to the diffuser 26, and forms an annular exhaust auxiliary space 40s centered on the axis Ar.

[0038] The auxiliary exhaust frame 40 has an opening 41 that opens radially outward Dro from within the exhaust auxiliary space 40s and communicates the exhaust space 30s with the exhaust auxiliary space 40s. This opening 41 is annular centered on the axis Ar. The upstream edge Dau of this opening 41 is defined by the downstream edge Dad of the inner diffuser 29 along the axis.

[0039] The auxiliary exhaust frame 40 has a downstream end plate 42 of the frame, an upstream end plate 43 of the frame, an inner peripheral plate 44 of the frame, and a support plate 47.

[0040] The frame downstream end plate 42 defines the edge of the downstream side Dad of the exhaust auxiliary space 40s in the axial direction. This frame downstream end plate 42 is an annular plate extending in a direction including a component in the radial direction Dr and the circumferential direction Dc. The radially outer edge Dro of this frame downstream end plate 42 is connected to the radially inner edge Dri of the casing downstream end plate 32. The inner surface of the frame downstream end plate 42 facing the exhaust auxiliary space 40s and the inner surface of the casing downstream end plate 32 facing the exhaust space 30s are smoothly continuous at the portion where the frame downstream end plate 42 and the casing downstream end plate 32 are connected. In this embodiment, the inner surface of the frame downstream end plate 42 facing the exhaust auxiliary space 40s and the inner surface of the casing downstream end plate 32 facing the exhaust space 30s are both surfaces extending in the radial direction Dr and the circumferential direction Dc, and are flush and connected to each other. Therefore, the inner surface of the frame downstream end plate 42 facing the exhaust auxiliary space 40s and the inner surface of the casing downstream end plate 32 facing the exhaust space 30s are located on a single virtual plane extending in the radial direction Dr and the circumferential direction Dc.

[0041] The edge of the downstream side Dad of the opening 41 is defined by the radially outer edge Dro of this frame downstream end plate 42.

[0042] The frame upstream end plate 43 defines the edge of the upstream side Dau of the exhaust auxiliary space 40s in the axial direction. This frame upstream end plate 43 is an annular plate extending in the radial direction Dr and the circumferential direction Dc. The radially outer edge Dro of this frame upstream end plate 43 is connected to the inner diffuser 29.

[0043] The inner peripheral plate 44 of the frame defines the edge of the radially inner side Dri in the exhaust auxiliary space 40s. This inner peripheral plate 44 of the frame connects the edge of the radially inner side Dri of the upstream end plate 43 of the frame and the edge of the radially inner side Dri of the downstream end plate 42 of the frame. The inner peripheral plate 44 of the frame has an upstream inner peripheral plate 45 and a downstream inner peripheral plate 46. The upstream inner peripheral plate 45 forms an annular shape centered on the axis Ar and extends in the axial direction Da. The edge of the upstream side Dau of this upstream inner peripheral plate 45 is connected to the edge of the radially inner side Dri of the upstream end plate 43 of the frame. The downstream inner peripheral plate 46 forms an annular shape centered on the axis Ar and extends gradually toward the radially outer side Dro as it goes toward the downstream side Dad of the axis. The edge of the upstream side Dau of this downstream inner peripheral plate 46 is connected to the edge of the downstream side Dad of the upstream inner peripheral plate 45. The edge of the downstream side Dad of this downstream inner peripheral plate 46 is connected to the edge of the radially inner side Dri of the downstream end plate 42 of the frame.

[0044] The support plate 47 is an annular member that spreads in the radial direction Dr and the circumferential direction Dc. The radially outer end Dro of the support plate 47 is connected to the inner peripheral plate 44 of the frame. The upstream end of the inner diffuser 29 on the axis side is connected to the support plate 47 by a diffuser connection portion 48. A plurality of bolt holes 47h penetrating in the axial direction Da are formed in the support plate 47.

[0045] The bearing device 50 rotatably supports the turbine rotor 11 and supports the portion on the downstream side Dad of the axis in the rotor shaft 12 that is downstream of the final moving blade row 13a. This bearing device 50 has a bearing 51 disposed opposite to the surface of the rotor shaft 12 and a bearing box 52 that supports the bearing 51 and covers the bearing 51. The bearing box 52 has an upstream side plate 53 disposed on the upstream side Dau of the axis of the bearing 51.

[0046] The shaft seal assembly 60 is disposed around the portion on the downstream side Dad of the axis in the rotor shaft 12 that is downstream of the final moving blade row 13a and on the upstream side Dau of the axis of the bearing device 50, and suppresses the steam from flowing from the upstream side Dau of its own axis to the downstream side Dad of its own axis.

[0047] This shaft seal assembly 60 includes a plurality of seal rings 61, a seal retaining ring 62, a bellows device 70, an outer peripheral side partition member 75, and a weight insertion tube 80.

[0048] Each of the plurality of seal rings 61 is annular about the axis Ar and is disposed to face a portion on the downstream side Dad of the axis of the last moving blade row 13a and on the upstream side Dau of the axis of the bearing device 50 in the rotor shaft 12, and can suppress the steam flowing from the upstream side Dau of its own axis to the downstream side Dad of its own axis.

[0049] The seal retaining ring 62 includes a retaining ring body 63, a bellows side connection flange 64, and a bearing side connection member 65.

[0050] The retaining ring body 63 has an annular cross section perpendicular to the axis Ar and is disposed around the plurality of annular seal rings 61 to support the plurality of seal rings 61. The bellows side connection flange 64 is annular about the axis Ar and protrudes radially outward Dro from the outer peripheral side portion of the retaining ring body 63 on the upstream side Dau of the axis of the retaining ring body 63. A plurality of bolt holes 64h penetrating in the axial direction Da are formed in the bellows side connection flange 64.

[0051] The bearing-side connection member 65 is connected to the holding ring body 63 and is also connected to the bearing housing 52. As shown in FIGS. 2 and 6, this bearing-side connection member 65 has a plurality of legs 66, a bearing-side connection flange 67, a shim 68, and a holding ring connection bolt 69. Each of the plurality of legs 66 is connected to a portion on the downstream side Dad of the axis of the holding ring body 63 and on the radially outer side Dro, and has a portion extending from the holding ring body 63 to the downstream side Dad of the axis. The plurality of legs 66 are arranged at intervals in the circumferential direction Dc with respect to the axis Ar. The bearing-side connection flange 67 is provided at the end on the downstream side Dad of the plurality of legs 66 and extends in the circumferential direction Dc with respect to the axis Ar. A bolt hole 67h penetrating in the axial direction Da is formed in this bearing-side connection flange 67. The shim 68 is disposed between the bearing-side connection flange 67 and the upstream side plate 53 of the bearing housing 52 in the axial direction Da. This shim 68 is disposed to adjust the relative position in the axial direction Da of the holding ring body 63 with respect to the bearing housing 52. The holding ring connection bolt 69 is inserted through the bolt hole 67h of the bearing-side connection flange 67 and is screwed into the upstream side plate 53 of the bearing housing 52.

[0052] The holding ring body 63, the plurality of legs 66 and the bearing-side connection flange 67 of the bearing-side connection member 65 are metallically bonded to each other and integrated. In the present embodiment, the holding ring body 63 and the plurality of legs 66 are joined by welding, and the plurality of legs 66 and the bearing-side connection flange 67 are joined by welding.

[0053] As shown in FIGS. 2 to 4, the bellows device 70 has a bellows 71, a first connection flange 72, a second connection flange 73, and a bellows connection bolt 74.

[0054] The bellows 71 is cylindrical with the axis Ar as the center and extends in the axial direction Da, and is expandable and contractible in the axial direction Da. The first connection flange 72 is annular with the axis Ar as the center and is provided at the end on the upstream side Dau of the axis of the bellows 71. The second connection flange 73 is annular with the axis Ar as the center and is provided at the end on the downstream side Dad of the axis of the bellows 71. A plurality of screw holes 73h are formed in the second connection flange 73, which are recessed from the end face on the downstream side Dad of the axis of the second connection flange 73 toward the upstream side Dau of the axis. These screw holes 73h are formed between the position of the minimum inner diameter Rb of the bellows 71 and the position of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr with respect to the axis Ar in the annular second connection flange 73. The bellows connection bolt 74 is inserted into the bolt hole 64h in the bellows-side connection flange 64 of the seal holding ring 62 and is screwed into the screw hole 73h of the second connection flange 73. Therefore, the bellows device 70 is connected to the seal holding ring 62 by this bellows connection bolt 74.

[0055] The outer peripheral side partition member 75 connects the bellows device 70 to the inner diffuser 29 and the auxiliary exhaust frame 40 of the exhaust casing 30. This outer peripheral side partition member 75 partitions the space between the outer peripheral side of the bellows device 70 and the inner peripheral side of the inner diffuser 29 into a space on the upstream side Dau of the axis and a space on the downstream side Dad of the axis.

[0056] The outer peripheral side partition member 75 has a casing-side connection flange 76, a partition member connection bolt 77, and a conical portion 78.

[0057] The casing-side connection flange 76 forms an annulus centered on the axis Ar, is located on the downstream side Dad of the axis and on the radially outer side Dro with respect to the end of the upstream side Dau of the axis of the bellows device 70, and can be connected to the support plate 47 of the exhaust casing 30. A plurality of screw holes 76h are formed in the casing-side connection flange 76, which are recessed from the end face on the downstream side Dad of the axis of the casing-side connection flange 76 toward the upstream side Dau of the axis. The partition member connection bolt 77 is inserted through the bolt hole 47h of the support plate 47 and screwed into the screw hole 76h of the casing-side connection flange 76. Therefore, the outer peripheral side partition member 75 is connected to the support plate 47 of the exhaust casing 30 by this partition member connection bolt 77.

[0058] As shown in FIGS. 4 and 5, the conical portion 78 connects the casing-side connection flange 76 and the end of the upstream side Dau of the axis of the bellows device 70. The conical portion 78 has an outer peripheral surface 78o and an inner peripheral surface 78i. The outer peripheral surface 78o forms a conical surface centered on the axis Ar such that the outer diameter gradually increases toward the downstream side Dad of the axis. The inner peripheral surface 78i forms a conical surface centered on the axis Ar such that the inner diameter gradually increases toward the downstream side Dad of the axis. The end of the upstream side Dau of the axis of the conical portion 78 is connected to the first connection flange 72, which is the end of the upstream side Dau of the axis of the bellows device 70, and the end of the downstream side Dad of the axis of the conical portion 78 is connected to the casing-side connection flange 76.

[0059] The weight insertion tube 80 is connected to the conical portion 78 such that the tube center axis Lc of the weight insertion tube 80 is along the generatrix Lb on the outer peripheral surface 78o of the conical portion 78, and at least a part of one side in the radial direction with respect to the tube center axis Lc is exposed to the outer peripheral side from the outer peripheral surface 78o, and at least a part of the other side in the radial direction with respect to the tube center axis Lc is exposed to the inner peripheral side from the inner peripheral surface 78i.

[0060] Therefore, the extending direction of the weight insertion tube 80 is inclined with respect to the axis Ar in a virtual plane including the axis Ar, such that the end on the downstream side Dad of the axis is located on the radially outer side Dro with respect to the end on the upstream side Dau of the axis, similar to the outer peripheral surface 78o of the conical portion 78. Here, the fact that the tube center axis Lc of the weight insertion tube 80 follows the generatrix Lb includes not only the case where the tube center axis Lc coincides with the generatrix Lb or the case where the tube center axis Lc is parallel to the generatrix Lb, but also the case where the inclination of the tube center axis Lc with respect to the generatrix Lb is within 3°.

[0061] As described above, the weight insertion tube 80 is provided in the conical portion 78 such that the weight attachment portion 12w in the rotor shaft 12 is located on the extension line of the tube center axis Lc of the weight insertion tube 80. Both ends of the weight insertion tube 80 in the direction in which the weight insertion tube 80 extends are open. Therefore, when looking into the weight insertion tube 80 from the opening on the downstream side Dad of the axis, the weight attachment portion 12w in the rotor shaft 12 can be seen. Note that during the operation of the steam turbine, the opening on the downstream side Dad of the axis is blocked by the plug 81.

[0062] In a steam turbine, the rotational balance of the turbine rotor 11 may be adjusted. At this time, as shown in FIGS. 3 and 4, the balance weight 90 is attached to the weight attachment portion 12w in the rotor shaft 12 using the weight rod 91. Alternatively, the balance weight 90 attached to the weight attachment portion 12w is removed using the weight rod 91. The balance weight 90 is attached to the tip of the weight rod 91, and by operating this weight rod 91, it is inserted into the weight insertion tube 80. A notch 76n is formed in the casing side connection flange 76 so that the weight rod 91 and the balance weight 90 attached to the tip thereof can be inserted into the weight insertion tube 80. Also, a notch 72n is formed in the first connection flange 72 of the bellows device 70 so that the weight rod 91 and the balance weight 90 attached to the tip thereof can be inserted into the weight insertion tube 80.

[0063] Next, the flow of steam in the steam turbine described above will be explained.

[0064] As shown in FIG. 1, steam flows into the turbine casing 21 through the steam inlet pipe 19. This steam flows in the turbine casing 21 toward the axial downstream side Dad. In this process, the steam impinges on a plurality of moving blades constituting a plurality of moving blade rows 13, rotating the turbine rotor 11.

[0065] The steam flowing out from the final moving blade row 13a of the turbine rotor 11 to the axial downstream side Dad flows into the diffuser space 26s. This steam flows in the diffuser space 26s toward the axial downstream side Dad while flowing radially outward toward Dro, and flows into the exhaust space 30s.

[0066] In the exhaust space 30s and in the region of the non-exhaust side Dpu with respect to the axis Ar, when the steam flowing into the exhaust space 30s along the inner peripheral surface of the outer diffuser 27 impinges on the casing outer peripheral plate 36, a part of it flows along the casing outer peripheral plate 36 toward the axial upstream side Dau, and the other part flows along the casing outer peripheral plate 36 toward the axial downstream side Dad.

[0067] The steam flowing along the casing outer peripheral plate 36 toward the axial upstream side Dau gradually changes its flow direction to the circumferential direction Dc and flows along this casing outer peripheral plate 36 toward the exhaust side Dpe. Then, this steam is exhausted from the exhaust port 31. On the other hand, the steam flowing along the casing outer peripheral plate 36 toward the axial downstream side Dad hits the casing downstream end plate 32 and flows radially inward Dri along this casing downstream end plate 32. Therefore, in the non-exhaust side Dpu in the exhaust space 30s, in the region along the casing downstream end plate 32, the steam flows backward. For this reason, in the non-exhaust side Dpu in the exhaust casing 30, in the region along the casing downstream end plate 32, a steam circulation region where the steam circulates may be formed.

[0068] On one hand, within the exhaust space 30s and within the region of the exhaust side Dpe with respect to the axis Ar, the vapor that has flowed into the exhaust space 30s along the inner peripheral surface of the outer diffuser 27 heads radially outward Dro and toward the exhaust side Dpe. For this reason, even if this vapor collides with the outer peripheral plate 36 of the casing or the downstream end plate 32 of the casing, it travels along the outer peripheral plate 36 of the casing or the downstream end plate 32 of the casing, radially outward Dro and toward the exhaust side Dpe, and is exhausted from the exhaust port 31. That is, within the exhaust space 30s and within the region of the exhaust side Dpe with respect to the axis Ar, substantial backflow of vapor does not occur.

[0069] In the case of low-load operation where the vapor flow rate flowing into the steam turbine is small, or when the condenser Co has a low vacuum degree, the amount of vapor backflow within the region of the non-exhaust side Dpu within the exhaust space 30s and with respect to the axis Ar increases.

[0070] In the present embodiment, within the region of the non-exhaust side Dpu within the exhaust space 30s and with respect to the axis Ar, the vapor that has flowed back radially inward Dri along the downstream end plate 32 of the casing enters the exhaust auxiliary space 40s from the opening 41 of the auxiliary exhaust frame 40. This vapor flows through the exhaust auxiliary space 40s, flows out from the opening 41 of the auxiliary exhaust frame 40 within the region of the exhaust side Dpe within the exhaust space 30s and with respect to the axis Ar, and is exhausted from the exhaust port 31.

[0071] For this reason, in the present embodiment, even if backflow of vapor occurs within the region of the non-exhaust side Dpu within the exhaust space 30s and with respect to the axis Ar, the vapor circulation region within this region can be reduced, or the vapor circulation region can be eliminated.

[0072] Therefore, in the present embodiment, the exhaust resistance of the vapor is reduced, and the efficiency of the steam turbine can be increased.

[0073] Next, the effects of the shaft seal assembly 60 in the present embodiment will be described. Here, the shaft seal assembly described in the background art section is used as the shaft seal assembly for the comparative example.

[0074] In the shaft seal assembly 60 according to the present embodiment, since the weight insertion tube 80 is provided in the conical portion 78, the disc portion in the shaft seal assembly in the comparative example becomes unnecessary, and this disc portion can be omitted. Therefore, in the shaft seal assembly 60 according to the present embodiment, the size in the radial direction Dr can be made smaller than that in the comparative example.

[0075] In the comparative example, a weight insertion tube is provided in the disc portion which is a flat plate. On the other hand, in the present embodiment, the weight insertion tube 80 is provided in the conical portion 78 which has higher rigidity than the flat plate. Further, the weight insertion tube in the comparative example is provided in the disc portion such that the central axis of the tube of this weight insertion tube intersects the direction in which the disc portion which is a flat plate extends. On the other hand, the weight insertion tube 80 in the present embodiment is connected to the conical portion 78 such that the central axis Lc of the tube of this weight insertion tube 80 is along the generatrix Lb on the outer peripheral surface 78o of the conical portion 78. Therefore, in the present embodiment, the connection portion between the weight insertion tube 80 and the object to be installed can be made longer than that in the comparative example.

[0076] From the above, in the present embodiment, the direction in which the central axis Lc of the tube extends can be made more stable than in the comparative example. Therefore, in the present embodiment, the balance weight 90 can be more easily accessed to the target position via the weight insertion tube 80 than in the comparative example.

[0077] In the bearing side connection member 65 according to the present embodiment, the leg 66 and the bearing side connection flange 67 are integrally metal-bonded to the holding ring body 63. Therefore, the holding ring side connection flange in the comparative example becomes unnecessary, and the size in the axial direction Da of the seal holding ring 62 including the holding ring body 63 and the bearing side connection member 65 can be made smaller than that in the comparative example.

[0078] Here, if the position of the screw hole 73h or the bolt hole of the second connection flange 73 is radially outside Dro of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr, in this case, a part of the seal holding ring 62 needs to exist at the position where the screw hole 73h or the bolt hole is formed in the radial direction Dr. On the other hand, in the present embodiment, a screw hole 73h is formed between the position of the minimum inner diameter Rb of the bellows 71 and the position of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr. Therefore, in the present embodiment, the size of the seal holding ring 62 in the radial direction Dr can be reduced.

[0079] As described above, in the present embodiment, the sizes of the shaft seal assembly 60 in the radial direction Dr and the axial direction Da can be made smaller than those in the comparative example. For this reason, in the present embodiment, the degree of freedom in the design of the inner diffuser 29 and the exhaust casing 30 is increased. In this regard, in the present embodiment, an auxiliary exhaust frame 40 can be provided in the exhaust casing 30, or the shape of the inner diffuser 29 can be easily made into an appropriate shape.

[0080] "Modification Example" In the above embodiment, the auxiliary exhaust frame 40 of the exhaust casing 30 and the outer peripheral side partition member 75 are connected. However, a support plate 47 may be connected to the diffuser connecting portion 48 connected to the inner diffuser 29 to connect the inner diffuser 29 and the outer peripheral side partition member 75.

[0081] In the above embodiment, the holding ring main body 63, the plurality of legs 66 of the bearing side connection member 65, and the bearing side connection flange 67 are joined to each other by welding and integrated. However, the holding ring main body 63, the plurality of legs 66, and the bearing side connection flange 67 may be integrally formed by casting to integrally bond them to each other.

[0082] The present disclosure is not limited to the embodiments described above. Various additions, changes, replacements, partial deletions, etc. are possible without departing from the conceptual ideas and spirits of the present invention derived from the content defined in the claims and their equivalents.

[0083] "Supplementary Note" The shaft seal assembly 60 in the above embodiments is understood as follows, for example.

[0084] (1) The shaft seal assembly in the first aspect targets the following steam turbine. This steam turbine includes a turbine rotor 11 having a rotor shaft 12 rotatable about an axis Ar and a plurality of moving blade rows 13 attached to the rotor shaft 12 in an axial direction Da along which the axis Ar extends, a turbine casing 21 covering the outer peripheral side of the plurality of moving blade rows 13, among the plurality of moving blade rows 13, a diffuser 26 disposed on the downstream side Dad of the axis with respect to the most downstream moving blade row 13a among the upstream side Dau and the downstream side Dad of the axis in the axial direction Da, through which the steam passing through the final moving blade row 13a passes and which defines a diffuser space 26s that gradually expands toward the radially outer side Dro with respect to the axis Ar as it moves toward the downstream side Dad of the axis, an exhaust casing 30 having an exhaust port 31 opening toward the radially outer side Dro and defining an exhaust space capable of guiding the steam passing through the diffuser space 26s to the exhaust port 31, and a bearing device 50 that rotatably supports the turbine rotor 11 and supports a portion of the rotor shaft 12 on the downstream side Dad of the axis with respect to the final moving blade row 13a within the rotor shaft 12. The diffuser 26 has an outer diffuser 27 whose cross-section perpendicular to the axis Ar forms an annular shape and gradually expands toward the radially outer side Dro as it moves toward the downstream side Dad of the axis, and defines the edge of the radially outer side Dro of the diffuser space 26s, and an inner diffuser 29 whose cross-section perpendicular to the axis Ar forms an annular shape and gradually expands toward the radially outer side Dro as it moves toward the downstream side Dad of the axis, and defines the edge of the radially inner side Dri with respect to the axis Ar of the diffuser space 26s. The bearing device 50 has a bearing 51 disposed opposite to the surface of the rotor shaft 12 and a bearing box 52 that supports and covers the bearing 51. The shaft seal assembly 60 forms an annular shape centered on the axis Ar, and is disposed opposite to a portion on the downstream side Dad of the axis with respect to the final moving blade row 13a and on the upstream side Dau of the axis with respect to the bearing device 50 in the rotor shaft 12, and can suppress the steam from flowing from the upstream side Dau of its own axis to the downstream side Dad of its own axis. A seal ring 61, a seal holding ring 62 having an annular cross-section perpendicular to the axis Ar and disposed around the annular seal ring 61 to support the seal ring 61, a bellows device 70 having a cylindrical shape centered on the axis Ar and extending in the axial direction Da, being expandable and contractible in the axial direction Da, and having an end on the downstream side Dad of the axis connected to the seal holding ring 62, an outer peripheral side partition member 75 capable of connecting the end on the upstream side Dau of the axis of the bellows device 70 to the exhaust casing 30 or the inner diffuser 29, and a weight insertion tube 80 through which a balance weight 90 attachable to the rotor shaft 12 can be inserted. The outer peripheral side partition member 75 forms an annular shape centered on the axis Ar, is located on the downstream side Dad of the axis with respect to the end on the upstream side Dau of the axis of the bellows device 70 and on the outer diameter side Dro with respect to the bellows device 70, and has a casing side connection flange 76 connectable to the exhaust casing 30 or the inner diffuser 29, and a conical portion 78 connecting the casing side connection flange 76 and the end on the upstream side Dau of the axis of the bellows device 70. The conical portion 78 has an outer peripheral surface 78o and an inner peripheral surface 78i. The outer peripheral surface 78o forms a conical surface shape centered on the axis Ar such that the outer diameter gradually increases as it goes toward the downstream side Dad of the axis. The inner peripheral surface 78i forms a conical surface shape centered on the axis Ar such that the inner diameter gradually increases as it goes toward the downstream side Dad of the axis. The end on the upstream side Dau of the axis of the conical portion 78 is connected to the end on the upstream side Dau of the axis of the bellows device 70, and the end on the downstream side Dad of the axis of the conical portion 78 is connected to the casing side connection flange 76.The weight insertion tube 80 is connected to the conical portion 78 such that the central axis Lc of the weight insertion tube 80 is along the generatrix Lb on the outer peripheral surface 78o of the conical portion 78, and at least a part of one side in the radial direction Dr with respect to the central axis Lc of the tube is exposed to the outer peripheral side from the outer peripheral surface 78o, and at least a part of the other side in the radial direction Dr with respect to the central axis Lc of the tube is exposed to the inner peripheral side from the inner peripheral surface 78i.

[0085] Here, a shaft seal assembly as a comparative example will be described. This shaft seal assembly includes a seal ring, a seal retaining ring, a bellows device, an outer peripheral side partitioning member, and a weight insertion tube.

[0086] The seal ring is annular about an axis, similar to the seal ring 61 of the present embodiment, and is disposed opposite to the outer peripheral surface of the rotor shaft. The seal retaining ring is disposed around the seal ring and supports the seal ring. The bellows device is cylindrical about an axis and extends in the axial direction. The downstream end of the bellows device in the axial direction is connected to the seal retaining ring.

[0087] The outer peripheral side partitioning member connects the bellows device and the inner diffuser. This outer peripheral side partitioning member partitions the space between the outer peripheral side of the bellows device and the inner peripheral side of the inner diffuser into an upstream space and a downstream space in the axial direction. This outer peripheral side partitioning member includes a bellows side connection portion, a disk portion, a conical portion, and a casing side connection flange. The bellows side connection portion is annular about an axis and is connected to the downstream end of the bellows device in the axial direction. The disk portion is annular about an axis and is a flat plate perpendicular to the axis. This disk portion is connected to the radially outer end of the bellows side connection portion. The conical portion has an outer peripheral surface and an inner peripheral surface, similar to the conical portion 78 of the present embodiment. The outer peripheral surface and the inner peripheral surface are conical surface-shaped about the axis, similar to the outer peripheral surface 78o and the inner peripheral surface 78i of the conical portion 78 of the present embodiment. The upstream end of the conical portion in the axial direction is connected to the radially outer edge of the disk portion. The casing side connection flange is annular about an axis, is connected to the downstream end of the conical portion in the axial direction, and is connected to the inner diffuser.

[0088] The weight insertion tube is capable of inserting a balance weight attachable to the rotor shaft. The weight insertion tube is provided in the disk portion such that the central axis of the tube of this weight insertion tube is inclined with respect to the axis and intersects the direction in which the disk portion spreads.

[0089] That is, the shaft seal assembly in this comparative example is the shaft seal assembly described in the background art section.

[0090] In the shaft seal assembly 60 in this aspect, since the weight insertion tube 80 is provided in the conical portion 78, the disk portion in the shaft seal assembly 60 in the comparative example becomes unnecessary, and this disk portion can be omitted. For this reason, in the shaft seal assembly 60 in this aspect, the size in the radial direction Dr can be made smaller than in the comparative example.

[0091] In the comparative example, the weight insertion tube is provided in the disk portion which is a flat plate. On the other hand, in this aspect, the weight insertion tube 80 is provided in the conical portion 78 which has higher rigidity than the flat plate. Also, the weight insertion tube in the comparative example is provided in the disk portion such that the central axis of the tube of this weight insertion tube intersects the direction in which the disk portion which is a flat plate spreads. On the other hand, the weight insertion tube 80 in this aspect is connected to the conical portion 78 such that the central axis Lc of the tube of this weight insertion tube 80 follows the generatrix Lb on the outer peripheral surface 78o of the conical portion 78. For this reason, in this aspect, the connection portion between the weight insertion tube 80 and the object to be installed can be made longer than in the comparative example. Therefore, in this aspect, the direction in which the central axis Lc of the tube extends can be stabilized more than in the comparative example. For this reason, in this aspect, it is easier to access the balance weight 90 to the target position via the weight insertion tube 80 than in the comparative example.

[0092] (2) The shaft seal assembly in the second aspect is In the shaft seal assembly 60 in the first aspect, the bellows device 70 forms a cylindrical shape centered on the axis Ar and extends in the axial direction Da, and includes a bellows 71 that can expand and contract in the axial direction Da; a first connection flange 72 that forms an annular shape centered on the axis Ar, is provided at an end on the upstream side Dau of the axis of the bellows 71, and to which the end on the upstream side Dau of the conical portion 78 is connected; a second connection flange 73 that forms an annular shape centered on the axis Ar and is provided at an end on the downstream side Dad of the axis of the bellows 71; and a bellows connection bolt 74 that connects the second connection flange 73 and the seal retaining ring 62. The first connection flange 72 is connected to the end on the upstream side Dau of the axis of the conical portion 78. The second connection flange 73 has a screw hole 73h that is recessed from the end face on the downstream side Dad of the second connection flange 73 toward the upstream side Dau of the axis and into which the bellows connection bolt 74 can be screwed. The screw hole 73h is formed between the position of the minimum inner diameter Rb of the bellows 71 and the position of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr with respect to the axis Ar in the annular second connection flange 73.

[0093] Suppose that the position of the screw hole 73h or the bolt hole of the second connection flange 73 is radially outside Dro of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr with respect to the axis Ar. In this case, a part of the seal retaining ring needs to be present at the position where the screw hole 73h or the bolt hole is formed in the radial direction Dr. On the other hand, in this aspect, the screw hole 73h is formed between the position of the minimum inner diameter Rb of the bellows 71 and the position of the maximum outer diameter Ra of the bellows 71 in the radial direction Dr with respect to the axis Ar. Therefore, in this aspect, the size of the seal retaining ring 62 in the radial direction Dr can be reduced.

[0094] (3) The shaft seal assembly in the third aspect is In the shaft seal assembly 60 in the first aspect or the second aspect, the seal retaining ring 62 forms an annular shape centered on the axis Ar, is disposed around the annular seal ring 61, and includes a retaining ring body 63 that supports the seal ring 61. It has a bearing-side connection member 65 that is connected to the holding ring body 63 and can be connected to the bearing housing 52. The bearing-side connection member 65 is connected to the holding ring body 63 and has a leg 66 having a portion extending from the holding ring body 63 to the downstream side Dad of the axis. A bearing-side connection flange 67 is provided at the end of the leg 66 on the downstream side Dad of the axis, extends in the circumferential direction Dc with respect to the axis Ar, and has a bolt hole 67h formed to penetrate in the axis direction Da. It also has a holding ring connection bolt 69 that is inserted through the bolt hole 67h of the bearing-side connection flange 67 and can be screwed into the bearing housing 52. The holding ring body 63, the leg 66 of the bearing-side connection member 65, and the bearing-side connection flange 67 are integrally metal-bonded to each other.

[0095] Here, a shaft seal assembly as a comparative example will be described. This shaft seal assembly has a seal ring, a seal holding ring, and a bearing-side connection member.

[0096] The bearing-side connection member connects the seal holding ring and the bearing device. This bearing-side connection member has a holding ring-side connection flange, a body extending in the axis direction, and a bearing-side connection flange. The holding ring-side connection flange is provided at the end of the body on the upstream side of the axis. The bearing-side connection flange is provided at the end of the body on the downstream side of the axis.

[0097] That is, the shaft seal assembly in this comparative example is the shaft seal assembly described in the background art section.

[0098] In the bearing-side connection member 65 in this aspect, the leg 66 and the bearing-side connection flange 67 are integrally metal-bonded to the holding ring body 63. Therefore, the holding ring-side connection flange in the comparative example becomes unnecessary, and the size of the seal holding ring 62 including the holding ring body 63 and the bearing-side connection member 65 in the axis direction Da can be made smaller than that in the comparative example.

[0099] (4) The shaft seal assembly in the fourth aspect is In the shaft seal assembly 60 in the third aspect, the bearing-side connection member 65 has a shim 68 that can be disposed between the bearing-side connection flange 67 and the bearing housing 52.

[0100] In this aspect, the number of shims 68 or the thickness of the shims 68 can be adjusted, and the relative position of the seal retaining ring 62 in the axial direction Da with respect to the bearing housing 52 can be adjusted.

[0101] (5) The shaft seal assembly in the fifth aspect is In the shaft seal assembly 60 in the third aspect or the fourth aspect, the bearing-side connection member 65 has a plurality of the legs 66. The plurality of the legs 66 are connected to the retaining ring body 63 and are arranged at intervals from each other in the circumferential direction Dc with respect to the axis Ar. The bearing-side connection flange 67 is provided at the end of the plurality of the legs 66 on the downstream side Dad of the axis.

[0102] The steam turbine in the above embodiments is understood as follows, for example. (6) The steam turbine in the sixth aspect is comprising the shaft seal assembly 60 in any one of the first aspect to the fifth aspect, the turbine rotor 11, the turbine casing 21, the diffuser 26, the exhaust casing 30, and the bearing device 50.

[0103] (7) The steam turbine in the seventh aspect is In the steam turbine in the sixth aspect, the exhaust casing 30 includes a part of the region on the inner side Dri in the radial direction and on the downstream side Dad of the axis with respect to the diffuser 26, and has an auxiliary exhaust frame 40 that defines an annular exhaust auxiliary space 40s centered on the axis Ar. The exhaust auxiliary space 40s communicates with the exhaust space 30s.

[0104] In this aspect, the exhaust resistance of the steam can be reduced, and the efficiency of the steam turbine can be increased.

[0105] (8) The steam turbine in the eighth aspect is In the steam turbine in the seventh aspect, the casing-side connection flange 76 of the outer peripheral side partition member 75 is connected to the auxiliary exhaust frame 40 of the exhaust casing 30.

Explanation of symbols

[0106] 10a: First steam turbine section 10b: Second steam turbine section 11: Turbine rotor 12: Rotor shaft 12w: Weight attachment part 13: Moving blade row 13a: Final moving blade row 17: Stationary blade row 18: Bearing 19: Steam inlet pipe 20: Casing 21: Turbine casing 25: Exhaust chamber 26: Diffuser 26s: Diffuser space 27: Outer diffuser 29: Inner diffuser 30: Exhaust casing 30s: Exhaust space 31: Exhaust port 32: Casing downstream end plate 34: Casing upstream end plate 36: Casing outer peripheral plate 40: Auxiliary exhaust frame 40s: Exhaust auxiliary space 41: Opening 42: Frame downstream end plate 43: Frame upstream end plate 44: Frame inner peripheral plate 45: Upstream inner peripheral plate 46: Downstream inner peripheral plate 47: Support plate 47h: Bolt hole 48: Diffuser connection part 50: Bearing device 51: Bearing 52: Bearing box 53: Upstream side plate 60: Shaft seal assembly 61: Seal ring 62: Seal retaining ring 63: Retaining ring body 64: Bellows side connection flange 64h: Bolt hole 65: Bearing side connection member 66: Leg 67: Bearing side connection flange 67h: Bolt hole 68: Shim 69: Retaining ring connection bolt 70: Bellows device 71: Bellows 72: First connection flange 72n: Notch 73: Second connection flange 73h: Threaded hole 74: Bellows connection bolt 75: Outer peripheral side partition member 76: Casing side connection flange 76h: Threaded hole 76n: Notch 77: Partition member connection bolt 78: Conical part 78o: Outer peripheral surface 78i: Inner peripheral surface 80: Weight insertion tube 81: Plug 90: Balance weight 91: Rod for weight Co: Condenser Lb: Bus bar Lc: Tube center axis Ar: Axis Da: Axial direction Dau: Axial upstream side Dad: Axial downstream side Dc: Circumferential direction Dr: Radial direction Dri: Radial inner side Dro: Radial outer side Dpe: Exhaust side Dpu: Non-exhaust side

Claims

1. A turbine rotor having a rotor shaft rotatable about an axis, and a plurality of moving blade rows attached to the rotor shaft arranged in the axial direction in which the axis extends; A turbine casing covering the outer peripheral side of the plurality of moving blade rows; Among the plurality of moving blade rows, it is arranged on the downstream side of the axis with respect to the most downstream moving blade row which is the moving blade row on the most downstream side of the upstream side and the downstream side of the axis in the axial direction, and the steam that has passed through the most downstream moving blade row passes through it, and a diffuser that defines a diffuser space that gradually expands radially outward with respect to the axis as it goes downstream along the axis; An exhaust casing having an exhaust port opening radially outward and defining an exhaust space capable of guiding the steam that has passed through the diffuser space to the exhaust port; A bearing device that rotatably supports the turbine rotor and supports a portion of the rotor shaft downstream of the axis with respect to the most downstream moving blade row; Comprising; The diffuser is An outer diffuser whose cross-section perpendicular to the axis forms an annular shape and gradually expands radially outward as it goes downstream along the axis, and defines the radially outer edge of the diffuser space; An inner diffuser whose cross-section perpendicular to the axis forms an annular shape and gradually expands radially outward as it goes downstream along the axis, and defines the radially inner edge of the diffuser space with respect to the axis; Having; The bearing device has a bearing disposed opposite to the surface of the rotor shaft, and a bearing box that supports and covers the bearing; In the shaft seal assembly of a steam turbine, A seal ring that forms an annular shape around the axis, is disposed opposite to a portion of the rotor shaft that is downstream of the axis with respect to the most downstream moving blade row and upstream of the axis with respect to the bearing device, and can suppress the steam flowing from the upstream side of its own axis to the downstream side of its own axis; A seal retaining ring whose cross-section perpendicular to the axis forms an annular shape and is disposed around the annular seal ring to support the seal ring; A bellows device that forms a cylindrical shape around the axis and extends in the axial direction, is axially expandable and contractible, and the downstream end in the axial direction is connected to the seal retaining ring; An outer peripheral side partition member capable of connecting the upstream end in the axial direction of the bellows device to the exhaust casing or the inner diffuser; A weight insertion tube through which a balance weight attachable to the rotor shaft can be inserted, having, wherein the outer peripheral side partition member, forms an annular shape around the axis, is located on the downstream side of the axis with respect to the upstream end of the bellows device in the axial direction and on the outer side in the radial direction with respect to the bellows device, and has a casing side connection flange connectable to the exhaust casing or the inner diffuser, a conical portion connecting the casing side connection flange and the upstream end of the bellows device in the axial direction of the axis, having, the conical portion has an outer peripheral surface and an inner peripheral surface. The outer peripheral surface forms a conical surface around the axis such that the outer diameter gradually increases toward the downstream side of the axis, and the inner peripheral surface forms a conical surface around the axis such that the inner diameter gradually increases toward the downstream side of the axis, the upstream end of the conical portion in the axial direction is connected to the upstream end of the bellows device in the axial direction, and the downstream end of the conical portion in the axial direction is connected to the casing side connection flange, the weight insertion tube is connected to the conical portion such that the tube central axis of the weight insertion tube is along the generatrix on the outer peripheral surface of the conical portion, and at least a part of one side in the radial direction with respect to the tube central axis is exposed to the outer peripheral side from the outer peripheral surface, and at least a part of the other side in the radial direction with respect to the tube central axis is exposed to the inner peripheral side from the inner peripheral surface, a shaft seal assembly.

2. In the shaft seal assembly according to Claim 1, the bellows device, forms a cylindrical shape around the axis and extends in the axial direction, and has a bellows that can expand and contract in the axial direction, forms an annular shape around the axis, is provided at the upstream end of the bellows in the axial direction, and has a first connection flange to which the upstream end of the conical portion in the axial direction is connected, forms an annular shape around the axis, and has a second connection flange provided at the downstream end of the bellows in the axial direction, a bellows connection bolt connecting the second connection flange and the seal retaining ring, having, the first connection flange is connected to the upstream end of the conical portion in the axial direction, the second connection flange has a screw hole recessed from the end face on the downstream side in the axial direction of the second connection flange toward the upstream side in the axial direction, and into which the bellows connection bolt can be screwed. The screw hole is formed between the position of the minimum inner diameter of the bellows and the position of the maximum outer diameter of the bellows in the radial direction with respect to the axis in the annular second connection flange. Shaft seal assembly.

3. In the shaft seal assembly according to claim 1, The seal retaining ring, Is annular about the axis and is disposed around the annular seal ring to support the seal ring, and a retaining ring body; A bearing-side connecting member that is connected to the retaining ring body and can be connected to the bearing housing; And has The bearing-side connecting member, A leg having a portion that is connected to the retaining ring body and extends downstream from the retaining ring body in the axial direction; A bearing-side connecting flange provided at an end on the downstream side of the leg in the axial direction, extending in the circumferential direction with respect to the axis, and having a bolt hole penetrating in the axial direction; A retaining ring connection bolt inserted through the bolt hole of the bearing-side connecting flange and screwing into the bearing housing; And has The retaining ring body, the leg of the bearing-side connecting member, and the bearing-side connecting flange are integrally formed by being metallically bonded to each other. Shaft seal assembly.

4. In the shaft seal assembly according to claim 3, The bearing-side connecting member has a shim that can be disposed between the bearing-side connecting flange and the bearing housing. Shaft seal assembly.

5. In the shaft seal assembly according to claim 3, The bearing-side connecting member has a plurality of the legs, The plurality of legs are connected to the retaining ring body and are arranged at intervals from each other in the circumferential direction with respect to the axis, The bearing-side connecting flange is provided at the downstream ends of the plurality of legs in the axial direction. Shaft seal assembly.

6. The shaft seal assembly according to any one of claims 1 to 5, The turbine rotor, The turbine casing, The diffuser, The exhaust casing, The bearing device, A steam turbine comprising.

7. In the steam turbine according to claim 6, The exhaust casing has an auxiliary exhaust frame that defines an exhaust auxiliary space that includes a part of the region on the radially inner side and downstream of the axis with respect to the diffuser and is annular about the axis, The exhaust auxiliary space communicates with the exhaust space. Steam turbine.

8. In the steam turbine according to claim 7, The casing-side connecting flange of the outer peripheral side partitioning member is connected to the auxiliary exhaust frame of the exhaust casing. Steam turbine.

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