Stationary vane segment and steam turbine equipped with same

Abstract

To realize size reduction of a steam turbine.SOLUTION: A stator blade segment comprises a plurality of stator blade rows including a first stator blade row and a second stator blade row, and a blade ring that holds the plurality of stator blade rows. Outer shrouds of the plurality of stator blades included in the plurality of stator blade rows have a gas path surface facing radially inward, a first side surface facing a first circumferential side, and a second side surface facing a second circumferential side. The plurality of outer shrouds included in the second stator blade row have a drain recovery groove and a drain transfer groove. The drain recovery groove is recessed from the gas path surface of the outer shroud toward a radially outward side and extends in the circumferential direction. The drain transfer groove communicates with the drain recovery groove, is recessed from the first side surface of the outer shroud toward the second circumferential side, and extends to an edge of the outer shroud on the radially outward side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a stator vane segment having a plurality of stator vanes, and a steam turbine including the stator vane segment. [Background technology]

[0002] A steam turbine includes a rotor, a plurality of rows of stator blades, and a turbine casing that covers these.

[0003] The rotor has a rotor shaft rotatable about its axis and a plurality of rotor blade rows attached to the rotor shaft and aligned in the axial direction along which the axis extends. The rotor blade rows are aligned in the axial direction. The stator blade rows are also aligned in the axial direction. Each of the stator blade rows is disposed axially upstream of one of the rotor blade rows.

[0004] If steam drain exists in the steam flow path inside a steam turbine, this drain causes wet loss, so for example, the steam turbine disclosed in Patent Document 1 below has a structure for discharging this drain.

[0005] This steam turbine has one outer ring that holds one of the multiple stator blade rows, and an upstream outer ring that holds another stator blade row adjacent to the one stator blade row on the axial upstream side of the one stator blade row. A gap is provided between the one outer ring and the upstream outer ring in the axial direction, and this gap forms a condensate discharge flow path for discharging condensate in the steam flow path to the outer periphery of the two outer rings. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 06-123202 Summary of the Invention [Problem to be solved by the invention]

[0007] Steam turbines are required to be more compact while maintaining their performance.

[0008] Therefore, an object of the present disclosure is to provide a technique that can achieve downsizing of a steam turbine while maintaining its performance. [Means for solving the problem]

[0009] In order to achieve the above object, a stator vane segment according to one aspect of the disclosure comprises: The turbine comprises a plurality of stator vane rows including a first stator vane row and a second stator vane row, and a blade ring that holds the plurality of stator vane rows. The plurality of stator vane rows are aligned in an axial direction along which an axis extends. Each of the plurality of stator vane rows has a plurality of stator vanes that are aligned in a circumferential direction about the axis. The plurality of stator vane rows each have a blade body extending in a radial direction about the axis, and an outer shroud provided on the radially outer side of the blade body in the radial direction. The outer shroud has a gas path surface facing the radially inner side, and a first side surface facing the first circumferential side of a first circumferential side and a second circumferential side facing the second circumferential side. The blade ring forms an annular shape centered on the axis. The blade ring has an inner circumferential surface facing radially inward, an outer circumferential surface facing radially outward, blade grooves recessed radially outward from the inner circumferential surface and extending circumferentially for each of the plurality of blade rows, and a drain discharge flow path. The outer shrouds of the plurality of stator vanes in the first stator vane row are fitted into first blade grooves among the blade grooves for each of the plurality of blade rows. The outer shrouds of the plurality of stator vanes in the second stator vane row are fitted into second blade grooves adjacent to the axial downstream side of the first blade groove among the blade grooves for each of the plurality of blade rows, located upstream or downstream in the axial direction relative to the first blade groove. The outer shrouds of the plurality of stator vanes in the second stator vane row all have drain recovery grooves and drain transfer grooves. The drain recovery grooves are recessed radially outward from the gas path surface of the outer shroud and extend circumferentially. The drain transfer groove communicates with the drain recovery groove, is recessed from the first side surface of the outer shroud toward the second circumferential side, and extends to the radially outer edge of the outer shroud. The drain discharge flow passage of the blade ring communicates with the drain transfer grooves of the outer shroud of the plurality of stator vanes in the second stator vane row, and opens at the outer peripheral surface.The drain transfer groove of the stator vane located on the second circumferential side of the stator vane located on the first circumferential side of the plurality of stator vanes in the second stator vane row forms, in cooperation with the second side surface of the stator vane located on the first circumferential side, a drain transfer passage that can guide the drain from the drain recovery groove to the drain discharge passage. The drain discharge passage of the blade ring communicates with the drain transfer passage and can discharge the drain from the drain transfer passage to the outer circumferential side of the blade ring.

[0010] In the stator vane segment of this aspect, a portion of the drain that has passed through the rotor blade row adjacent to the second stator vane row on the axial upstream side can be captured by the drain recovery grooves of each of the plurality of stator vanes in the second stator vane row. Some of the drain in the drain recovery groove flows to the first circumferential side within the drain recovery groove, and another portion of the drain in the drain recovery groove flows to the second circumferential side within the drain recovery groove. The drain that has flowed to the first circumferential side within the drain recovery groove flows into a drain transfer passage connected to the end of the drain recovery groove on the first circumferential side, and the drain that has flowed to the second circumferential side within the drain recovery groove flows into a drain transfer passage connected to the end of the drain recovery groove on the second circumferential side. The drain transfer passage connected to the end of the drain recovery groove on the first circumferential side is a passage formed by the drain transfer groove formed in the first side surface of the outer shroud on which the drain recovery groove is formed, and the second side surface of the outer shroud adjacent to the first circumferential side of the outer shroud. Furthermore, the drain transfer passage connected to the end of the drain recovery groove on the second circumferential side is a passage formed by the second side surface of the outer shroud on which the drain recovery groove is formed and the drain transfer groove formed on the first side surface of the outer shroud adjacent to the second circumferential side of the outer shroud. The drain that flows into each drain transfer passage flows radially outward within each drain transfer passage and flows into the drain discharge passage of the blade ring. The drain that flows into this drain discharge passage is discharged to the outer periphery of the blade ring.

[0011] As described above, the stator vane segment in this aspect has a flow path that can discharge drain in the steam flow path to the outer periphery of the blade ring, thereby suppressing wet loss due to drain and reducing performance degradation of the steam turbine. Furthermore, in this aspect, a drain transfer groove is formed in the first side surface of the outer shroud and is used as a drain transfer flow path, so there is no need to form a drain transfer flow path between multiple stator vane rows in the axial direction. Therefore, in this aspect, the distance between multiple stator vane rows in the axial direction can be shortened. Furthermore, in this aspect, one blade ring holds multiple stator vane rows. Therefore, in this aspect, the axial dimension of the steam turbine can be reduced.

[0012] That is, in this aspect, the steam turbine can be made more compact while maintaining its performance.

[0013] In order to achieve the above object, a steam turbine according to one aspect of the disclosure includes: The turbine includes the stator vane segment according to the above aspect, and a rotor rotatable about the axis on the inner peripheral side of the blade ring. [Effects of the Invention]

[0014] According to one aspect of the present disclosure, it is possible to achieve a more compact steam turbine while maintaining its performance. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an overall cross-sectional view of a steam turbine in an embodiment according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view of a blade ring and its surroundings in one embodiment according to the present disclosure. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 10 is a radially inner view of multiple outer shrouds in one embodiment according to the present disclosure. [Figure 6]FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 2 is a front view of a main portion of a stator blade row in a comparative example of an embodiment according to the present disclosure. [Figure 8] FIG. 2 is a cross-sectional view of a blade ring and its surroundings in a first modified example of an embodiment according to the present disclosure. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] 10 is a cross-sectional view of a blade ring and its surroundings in a second modified example of an embodiment according to the present disclosure. [Figure 11] FIG. 10 is a plan view of an outer shroud in a modified example of an embodiment according to the present disclosure, as viewed from the inside in the radial direction. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments and various modifications of the present disclosure will be described with reference to the drawings.

[0017] "Steam turbine embodiment" An embodiment of a steam turbine including a stator vane segment according to the present disclosure will be described in detail with reference to FIGS.

[0018] The steam turbine in this embodiment is a two-flow steam turbine, as shown in FIG. 1 . This steam turbine includes a first steam turbine section ST1 and a second steam turbine section ST2. Each of the first steam turbine section ST1 and the second steam turbine section ST2 includes a rotor 10 rotating about an axis Ar, a casing 20 covering the rotor 10, three blade rings 30 arranged in the casing 20, one or more stator vane rows 50 held by each blade ring 30, a bearing 15, and a steam inlet pipe 16. The rotor 10 of the first steam turbine section ST1 and the rotor 10 of the second steam turbine section ST2 are located on the same axis Ar and are connected to each other so as to be rotatable together. For convenience of the following explanation, the direction in which the axis Ar extends is referred to as the axial direction Da. Furthermore, one of the two sides of the axial direction Da is referred to as a first side Da1, and the other is referred to as a second side Da2.

[0019] The first steam turbine section ST1 and the second steam turbine section ST2 share a steam inlet pipe 16. In the first steam turbine section ST1, components other than the steam inlet pipe 16 are arranged on a first side Da1 in the axial direction Da with respect to the steam inlet pipe 16. In the first steam turbine section ST1, the second side Da2 forms the axial upstream side Dau, and the first side Da1 forms the axial downstream side Dad. In the second steam turbine section ST2, components other than the steam inlet pipe 16 are arranged on the second side Da2 with respect to the steam inlet pipe 16. In the second steam turbine section ST2, the first side Da1 forms the axial upstream side Dau, and the second side Da2 forms the axial downstream side Dad. The first steam turbine section ST1 and the second steam turbine section ST2 have the same shape and structure. However, the axial upstream side Dau in the second steam turbine section ST2 is on the opposite side in the axial direction Da from the axial upstream side Dau in the first steam turbine section ST1.

[0020] Each rotor 10 in the first steam turbine section ST1 and the second steam turbine section ST2 has a rotor shaft 11 extending in an axial direction Da about the axis Ar, and a plurality of rotor blade rows 12 fixed to the outer periphery of the rotor shaft 11 and arranged in the axial direction Da. The number of the rotor blade rows 12 is, for example, seven. A bearing 15 that rotatably supports the rotor shaft 11 is provided on the axial downstream side Dad of the rotor shaft 11. Each rotor blade row 12 has a plurality of rotor blades arranged in a circumferential direction Dc about the axis Ar. The rotor blades have a blade-shaped cross section perpendicular to a radial direction Dr about the axis Ar, and have blade bodies extending in the radial direction Dr. A plurality of stator blade rows 50 are arranged in the axial direction Da. One of the plurality of stator blade rows 50 is arranged at a position Dau on the axial upstream side of each rotor blade row 12. Therefore, the number of the plurality of stator blade rows 50 matches the number of the plurality of moving blade rows. Therefore, when the number of the plurality of moving blade rows is 7, the number of the plurality of stator blade rows is also 7. Each stator blade row 50 has a plurality of stator blades arranged in the circumferential direction Dc.

[0021] As shown in FIG. 2 , the stator blade 51 has a blade body 52, an inner shroud 54, and an outer shroud 55. The blade body 52 has a blade-shaped cross section perpendicular to the radial direction Dr, and extends in the radial direction Dr. The inner shroud 54 is provided at the end of the radially inner side Dri of the blade body 52. ​​The outer shroud 55 is provided at the end of the radially outer side Dro of the blade body 52. ​​A part of the steam flow path 17 through which steam S flows is formed between the inner shroud 54 and the outer shroud 55. Therefore, the blade body 52 is disposed within this steam flow path 17.

[0022] Each of the three blade rings 30 has a cylindrical shape centered on the axis Ar. As shown in FIG. 1 , the three blade rings 30 are aligned in the axial direction Da. As shown in FIG. 2 , the first blade ring 30a, which is the blade ring 30 located furthest upstream along the axis Dau, is fitted with a first stage stator blade row 50a, a second stage stator blade row 50b, a third stage stator blade row 50c, a fourth stage stator blade row 50d, and a fifth stage stator blade row 50e, among the multiple stator blade rows 50. As shown in FIG. 1 , the second blade ring 30b, which is adjacent to the axial downstream side Dad of the first blade ring 30a, is fitted with the sixth stage stator blade row 50. The third blade ring 30c, which is adjacent to the axial downstream side Dad of the second blade ring 30b, is fitted with the seventh stage stator blade row 50.

[0023] As shown in Fig. 1, each of the casings 20 in the first steam turbine section ST1 and the second steam turbine section ST2 has an inner casing 21, an exhaust casing 22, and a diffuser 23. The inner casing 21 is cylindrical and has an axis Ar as its center. Three blade rings 30 are attached to the inner peripheral side of the inner casing 21.

[0024] The diffuser 23 is annular with respect to the axis Ar and defines a diffuser space 23s that gradually widens radially outward Dro toward the axial downstream side Dad. Steam S that has passed through the seventh stage rotor blade row 12, which is the final stage rotor blade row, flows into the diffuser space 23s.

[0025] The exhaust casing 22 has an exhaust port 27. This exhaust port 27 opens radially outward Dro from the interior and vertically downward. A condenser C that converts the steam S back into water is connected to this exhaust port 27. The exhaust casing 22 forms an exhaust space 22s through which the steam S flows after passing through the diffuser space 23s. This exhaust space 22s extends around the outer periphery of the diffuser 23 in the circumferential direction Dc relative to the axis Ar, and guides the steam S that flows in from the diffuser space 23s to the exhaust port 27.

[0026] The exhaust casing 22 of the first steam turbine section ST1 and the exhaust casing 22 of the second steam turbine section ST2 are connected to each other and integrated together.

[0027] The steam inlet pipe 16 has a cylindrical shape centered on a pipe axis Ap. The pipe axis Ap passes through an intermediate position in the axial direction Da between the first stage stator vane row 50a of the first steam turbine section ST1 and the first stage stator vane row 50a of the second steam turbine section ST2, and extends vertically. The steam inlet pipe 16 is disposed above the axis Ar. The steam inlet pipe 16 guides steam S from the outside into the inner casing 21 of the first steam turbine section ST1 and the inner casing 21 of the second steam turbine section ST2.

[0028] 2, each of the three blade rings 30 including the first blade ring 30a has an inner circumferential surface 31i facing the radially inward direction Dri, an outer circumferential surface 31o facing the radially outward direction Dro, and a blade groove 32 into which an outer shroud 55 of the stator blade row 50 held by the blade ring 30 fits. The blade groove 32 is recessed from the inner circumferential surface 31i of the blade ring 30 toward the radially outward direction Dro and extends in the circumferential direction Dc. The first blade ring 30a has, as blade grooves 32, a first stage blade groove 32a into which the outer shroud 55 of the first stage stator blade row 50a fits, a second stage blade groove 32b into which the outer shroud 55 of the second stage stator blade row 50b fits, a third stage blade groove 32c into which the outer shroud 55 of the third stage stator blade row 50c fits, a fourth stage blade groove 32d into which the outer shroud 55 of the fourth stage stator blade row 50d fits, and a fifth stage blade groove 32e into which the outer shroud 55 of the fifth stage stator blade row 50e fits. Furthermore, this first blade ring 30a has a drain discharge flow passage 35 that discharges steam drain from the radially inner side Dri to the radially outer side Dro.

[0029] As shown in Figures 3 to 5, each of the blade bodies 52 of each of the multiple stator blades 51 in each stator blade row 50 has a leading edge 52f located at the axially most upstream side Dau of the blade body 52, a trailing edge 52r located at the axially most downstream side Dad of the blade body 52, and a pressure surface 52p and a suction surface 52n connecting the leading edge 52f and the trailing edge 52r. The pressure surface 52p is a concave surface facing the circumferential first side Dc1 of the circumferential first side Dc1 and the circumferential second side Dc2 in the circumferential direction Dc and recessed toward the circumferential second side Dc2. The suction surface 52n is a convex surface facing the circumferential second side Dc2 and protruding toward the circumferential second side Dc2. The suction surface 52n is back-to-back with the pressure surface 52p. Each outer shroud 55 for each of the multiple stator blades 51 in each stator blade row 50 has a gas path surface 56 facing the radially inner side Dri, a counter gas path surface 57 facing the radially outer side Dro and back-to-back with the gas path surface 56, a front surface 58f facing the axial upstream side Dau, a rear surface 58r facing the axial downstream side Dad, a first side surface 59a facing the circumferential first side Dc1, and a second side surface 59b facing the circumferential second side Dc2.

[0030] The outer shrouds 55 of each of the multiple stator blades 51 in the second stage stator blade row 50b, the third stage stator blade row 50c, the fourth stage stator blade row 50d, and the fifth stage stator blade row 50e further have a drain recovery groove 61, a drain transfer groove 62, a first side auxiliary transfer flow path 63, and a second side auxiliary transfer flow path 64.

[0031] The drain recovery groove 61 is recessed radially outwardly Dro from the gas path surface 56 of the outer shroud 55 and extends in the circumferential direction Dc. The drain recovery groove 61 is disposed in the outer shroud 55 on the axially upstream side Dau of the middle position in the axial direction Da of the blade body 52. The drain recovery groove 61 has a first drain recovery groove 61a located on a first circumferential side Dc1 relative to the blade body 52, and a second drain recovery groove 61b located on a second circumferential side Dc2 relative to the blade body 52. ​​The first drain recovery groove 61a extends on the first circumferential side Dc1 from the edge of the blade body 52 to the first side surface 59a. The second drain recovery groove 61b extends on the second circumferential side Dc2 from the edge of the blade body 52 to the second side surface 59b.

[0032] The drain transfer groove 62 communicates with the first drain recovery groove 61a, is recessed from the first side surface 59a of the outer shroud 55 toward the circumferential second side Dc2, and extends to an edge of the radially outer side Dro of the outer shroud 55. The groove width of this drain transfer groove 62 at the edge of the radially outer side Dro of the outer shroud 55 is wider than the groove width of the first drain recovery groove 61a at a position where it communicates with the drain recovery groove 61. Of two stator blades 51 adjacent to each other in the circumferential direction Dc among the multiple stator blades 51, the drain transfer groove 62 of the stator blade 51 located on the circumferential second side Dc2 forms, in cooperation with the second side surface 59b of the stator blade 51 located on the circumferential first side Dc1, a drain transfer passage 65 that can guide the drain from the drain recovery groove 61 to the drain discharge passage 35 of the blade ring 30.

[0033] The first-side auxiliary transfer flow path 63 has an inlet 63i that opens in a surface that defines the first drain collection groove 61a and an outlet 63o that opens in a surface that defines the drain transfer groove 62. The first-side auxiliary transfer flow path 63 can guide the drain in the first drain collection groove 61a into the drain transfer groove 62. That is, the first-side auxiliary transfer flow path 63 of the outer shroud 55 can guide the drain in the first drain collection groove 61a into the drain transfer flow path 65 formed by the drain transfer groove 62 of the outer shroud 55 and the second side surface 59b of the outer shroud 55 located on the first circumferential side Dc1 of the outer shroud 55. The second-side auxiliary transfer flow path 64 has an inlet 64i that opens in a surface that defines the second drain collection groove 61b and an outlet 64o that opens in the second side surface 59b at a position in the axial direction Da where the drain transfer groove 62 exists. The second-side auxiliary transfer flow path 64 can guide the drain in the second drain recovery groove 61b onto the second side surface 59b. That is, the second-side auxiliary transfer flow path 64 of the outer shroud 55 can guide the drain in the second drain recovery groove 61b into the drain transfer flow path 65 formed by the second side surface 59b of the outer shroud 55 and the drain transfer groove 62 of the outer shroud 55 located on the second circumferential side Dc2 of the outer shroud 55.

[0034] The flow path cross-sectional area of ​​the drain transfer flow path 65 is larger than the flow path cross-sectional area of ​​the first auxiliary transfer flow path 63 and the flow path cross-sectional area of ​​the second auxiliary transfer flow path 64 described above. Furthermore, the flow path cross-sectional area of ​​this drain transfer flow path 65 is larger than the combined area of ​​the flow path cross-sectional area of ​​the first auxiliary transfer flow path 63 and the flow path cross-sectional area of ​​the second auxiliary transfer flow path 64.

[0035] 5, the inlet 63i of the first auxiliary transfer flow channel 63 opens on the plane defining the drain recovery groove 61, closer to the first circumferential side Dc1 than the blade body 52. ​​The inlet 64i of the second auxiliary transfer flow channel 64 opens on the plane defining the drain recovery groove 61, closer to the second circumferential side Dc2 than the blade body 52.

[0036] Here, in the circumferential direction Dc, the side where the pressure surface 52p is present relative to the suction surface 52n of the blade body 52 is referred to as the circumferential pressure side, and the side opposite to this circumferential pressure side is referred to as the circumferential negative pressure side. In this embodiment, the circumferential positive pressure side is the circumferential first side Dc1, and the circumferential negative pressure side is the circumferential second side Dc2. As shown in Fig. 3, the outlet 63o of the first-side auxiliary transfer flow path 63 located on the circumferential first side Dc1, which is the circumferential positive pressure side, is located radially inward Dri of the outlet 64o of the second-side auxiliary transfer flow path 64 located on the circumferential second side Dc2, which is the circumferential negative pressure side.

[0037] As shown in Figures 2, 3, and 5, the drain discharge passage 35 of the first blade ring 30a has a plurality of annular passages 36, a plurality of inner passages 37, a plurality of inter-row collecting passages 38, and a plurality of outer discharge passages 39.

[0038] Each of the multiple annular flow passages 36 is annular about the axis Ar. The multiple annular flow passages 36 include a second-stage annular flow passage 36b, a third-stage annular flow passage 36c, a fourth-stage annular flow passage 36d, and a fifth-stage annular flow passage 36e. The second-stage annular flow passage 36b is provided at a position in the axial direction Da where the drain transfer grooves 62 for each of the multiple stator vanes 51 in the second-stage stator vane row 50b are located, and is in communication with the drain transfer grooves 62 for each of the multiple stator vanes 51 in the second-stage stator vane row 50b. The third-stage annular flow passage 36c is provided at a position in the axial direction Da where the drain transfer grooves 62 for each of the multiple stator vanes 51 in the third-stage stator vane row 50c are located, and is in communication with the drain transfer grooves 62 for each of the multiple stator vanes 51 in the third-stage stator vane row 50c. The fourth-stage annular flow passage 36d is provided at a position in the axial direction Da where the drain transfer grooves 62 for each of the plurality of stator vanes 51 in the fourth-stage stator vane row 50d are present, and is in communication with the drain transfer grooves 62 for each of the plurality of stator vanes 51 in the fourth-stage stator vane row 50d. The fifth-stage annular flow passage 36e is provided at a position in the axial direction Da where the drain transfer grooves 62 for each of the plurality of stator vanes 51 in the fifth-stage stator vane row 50e are present, and is in communication with the drain transfer grooves 62 for each of the plurality of stator vanes 51 in the fifth-stage stator vane row 50e.

[0039] A plurality of inner flow passages 37 are provided for each of the plurality of stator blade rows 50, and the number of the plurality of inner flow passages 37 for each of the plurality of stator blades 51 is, for example, less than 10. The plurality of inner flow passages 37 for each of the plurality of stator blades 51 are arranged at intervals from one another in the circumferential direction Dc around the axis Ar. Each of the plurality of inner flow passages 37 extends in the radial direction Dr. A radially inner end Dri of the inner flow passage 37 for one stator blade row 50 communicates with the annular flow passage 36 for that one stator blade row 50.

[0040] Each of the multiple interrow collecting passages 38 extends in a direction including the axial direction Da. The multiple interrow collecting passages 38 are arranged at intervals from one another in the circumferential direction Dc around the axis Ar. The number of the multiple interrow collecting passages 38 is the same as the number of the multiple inner passages 37 in one stator blade row 50, and is less than 10. The end of the radially outer side Dro of the inner passage 37 for one stator blade row 50 communicates with one of the multiple interrow collecting passages 38 that is located radially outward Dro of this inner passage 37.

[0041] Each of the multiple outer discharge passages 39 extends in the radial direction Dr. A radially inner end Dri of each outer discharge passage 39 communicates with the interrow collecting passage 38, and a radially outer end Dro of each outer discharge passage 39 opens at the outer peripheral surface 31o of the first blade ring 30a. The number of the multiple outer discharge passages 39 is the same as the number of the multiple interrow collecting passages 38. In other words, one outer discharge passage 39 is provided for one interrow collecting passage 38. Therefore, the number of the multiple outer discharge passages 39 is less than 10, which is smaller than the number of stator blades 51 that each stator blade row 50 has.

[0042] The stator vane segment VS in this embodiment has the above-described first blade ring 30a and a plurality of stator vane rows 50 held by this first blade ring 30a.

[0043] 2, at least a portion of the drain droplets present in the steam flow passage 17 between the inner peripheral side of the first blade ring 30a and the outer peripheral side of the rotor shaft 11 are captured in any of the drain recovery grooves 61 among the drain recovery grooves 61 for each of the plurality of stator vanes 51 of the second stage stator vane row 50b, the drain recovery grooves 61 for each of the plurality of stator vanes 51 of the third stage stator vane row 50c, the drain recovery grooves 61 for each of the plurality of stator vanes 51 of the fourth stage stator vane row 50d, and the drain recovery grooves 61 in the outer shroud 55 for each of the plurality of stator vanes 51 of the fifth stage stator vane row 50e. In this embodiment, as described above, the drain recovery grooves 61 are arranged in the outer shroud 55 on the axial upstream side Dau of the middle position in the axial direction Da of the blade body 52. Therefore, in this embodiment, a portion of the drain that has passed through one rotor blade row 12 adjacent to one stator blade row 50 on the axial upstream side Dau can be captured in the drain recovery groove 61 of each of the multiple stator blades 51 that one stator blade row 50 has before passing through this one stator blade row 50.

[0044] As shown in Figure 3, a portion of the drain in the drain recovery groove 61 flows through the first drain recovery groove 61a in the drain recovery groove 61 to the first circumferential side Dc1, and another portion of the drain in the drain recovery groove 61 flows through the second drain recovery groove 61b in the drain recovery groove 61 to the second circumferential side Dc2.

[0045] A portion of the drain flowing inside the first drain recovery groove 61a toward the circumferential first side Dc1 flows into a drain transfer flow path 65 connected to the end of the drain recovery groove 61 on the circumferential first side Dc1, via a first-side auxiliary transfer flow path 63 that is in communication with the first drain recovery groove 61a. The rest of the drain flowing inside the first drain recovery groove 61a toward the circumferential first side Dc1 flows directly into the drain transfer flow path 65. The drain that has flowed into the drain transfer flow path 65 flows inside the drain transfer flow path 65 toward the radially outer side Dro and flows into the annular flow path 36 of the drain discharge flow path 35.

[0046] A portion of the drain flowing inside the second drain recovery groove 61b toward the circumferential second side Dc2 flows into a drain transfer flow path 65 connected to the end of the drain recovery groove 61 on the circumferential second side Dc2, via a second-side auxiliary transfer flow path 64 that is in communication with the second drain recovery groove 61b. The rest of the drain flowing inside the second drain recovery groove 61b toward the circumferential second side Dc2 flows directly into the drain transfer flow path 65. The drain that has flowed into the drain transfer flow path 65 flows inside the drain transfer flow path 65 toward the radially outer side Dro and flows into the annular flow path 36 of the drain discharge flow path 35.

[0047] In this embodiment, the drain transfer flow passage 65 connected to the end of the first circumferential side Dc1 of the first drain recovery groove 61a is a flow passage formed by the drain transfer groove 62 formed in the first side surface 59a of the outer shroud 55 on which the first drain recovery groove 61a is formed, and the second side surface 59b of the outer shroud 55 adjacent to the first circumferential side Dc1 of the outer shroud 55. Furthermore, the drain transfer flow passage 65 connected to the end of the second circumferential side Dc2 of the second drain recovery groove 61b is a flow passage formed by the second side surface 59b of the outer shroud 55 on which the second drain recovery groove 61b is formed, and the drain transfer groove 62 formed in the first side surface 59a of the outer shroud 55 adjacent to the second circumferential side Dc2 of the outer shroud 55. In addition, drain from a first side auxiliary transfer flow path 63 formed in the outer shroud 55 located on the second circumferential side Dc2 of this drain transfer flow path 65 and drain from a second side auxiliary transfer flow path 64 formed in the outer shroud 55 located on the first circumferential side Dc1 of this drain transfer flow path 65 flow into one drain transfer flow path 65.

[0048] As described above, in this embodiment, the flow path cross-sectional area of ​​the drain transfer flow path 65 is larger than the combined flow path cross-sectional area of ​​the first auxiliary transfer flow path 63 and the second auxiliary transfer flow path 64. Therefore, in this embodiment, when drain is flowing directly into the drain transfer flow path 65 from the drain recovery groove 61, even if drain flows into the drain transfer flow path 65 from the first auxiliary transfer flow path 63 and the second auxiliary transfer flow path 64, the drain can flow smoothly within the drain transfer flow path 65.

[0049] When there is a large amount of drain in the steam flow path 17, even when some of the drain already captured in the drain recovery groove 61 flows through the drain recovery groove 61 toward the circumferential first side Dc1 and another part of the drain flows through the drain recovery groove 61 toward the circumferential second side Dc2, the drain may be captured in the drain recovery groove 61, causing the drain recovery groove 61 to become filled with drain. In this case, the drain recovery groove 61 is no longer able to capture any more drain, resulting in a decrease in the drain recovery rate. In this embodiment, some of the drain flowing through the drain recovery groove 61 toward the circumferential first side Dc1 flows into the first-side auxiliary transfer flow path 63, and some of the drain flowing through the drain recovery groove 61 toward the circumferential second side Dc2 flows into the second-side auxiliary transfer flow path 64, thereby preventing the drain recovery groove 61 from being filled with drain and causing a decrease in the drain recovery rate.

[0050] Furthermore, in this embodiment, as described above, the groove width of the drain transfer groove 62 at the edge on the radially outer side Dro of the outer shroud 55 is wider than the groove width at the position in the drain transfer groove 62 that communicates with the drain recovery groove 61. This makes it possible to improve the efficiency of drain discharge from the drain transfer passage 65 to the annular passage 36 of the drain discharge passage 35.

[0051] The pressure in the circumferential pressure side, which is the circumferential first side Dc1 with respect to the blade body 52, is higher than the pressure in the circumferential negative pressure side, which is the circumferential second side Dc2 with respect to the blade body 52. ​​Therefore, the pressure of drain in the first auxiliary transfer channel 63, in which the inlet 63i is formed on the circumferential positive pressure side, which is the circumferential first side Dc1 with respect to the blade body 52, is higher than the pressure of drain in the second auxiliary transfer channel 64, in which the inlet 64i is formed on the circumferential negative pressure side, which is the circumferential second side Dc2 with respect to the blade body 52. ​​Therefore, into one drain transfer channel 65, high-pressure drain from the first auxiliary transfer channel 63 formed in the outer shroud 55 and located on the circumferential second side Dc2 of this drain transfer channel 65, and low-pressure drain from the second auxiliary transfer channel 64 formed in the outer shroud 55 and located on the circumferential first side Dc1 of this drain transfer channel 65, flow.

[0052] 7, assume that the outlet 63zo of the first-side auxiliary transfer flow passage 63z, which is located on the circumferential first side Dc1 (the circumferential positive pressure side), is located radially outward Dro of the outlet 64zo of the second-side auxiliary transfer flow passage 64z, which is located on the circumferential second side Dc2 (the circumferential negative pressure side). In this case, low-pressure drain from the second-side auxiliary transfer flow passage 64z formed in the outer shroud 55 on the circumferential first side Dc1 of one drain transfer flow passage 65 flows toward the radially outer side Dro within this drain transfer flow passage 65. Meanwhile, while some of the high-pressure drain from the first-side auxiliary transfer flow passage 63z formed in the outer shroud 55 on the circumferential second side Dc2 of this drain transfer flow passage 65 flows toward the radially outer side Dro within this drain transfer flow passage 65, there is a risk that other drain will flow toward the radially inner side Dri within this drain transfer flow passage 65. For this reason, the drain with low pressure from the second auxiliary transfer flow path 64z may be hindered by the drain from the first auxiliary transfer flow path 63z from flowing toward the radially outer side Dro in this drain transfer flow path 65. That is, in this case, the flow of drain in the drain transfer flow path 65 may be impaired.

[0053] Therefore, in this embodiment, in order to ensure a smooth flow of drain within the drain transfer flow path 65, the outlet 63o of the first side auxiliary transfer flow path 63, which is located on the circumferential first side Dc1, which is the circumferential positive pressure side, is located radially inward Dri than the outlet 64o of the second side auxiliary transfer flow path 64, which is located on the circumferential second side Dc2, which is the circumferential negative pressure side.

[0054] The drain that has flowed into the annular flow passage 36 for each of the multiple stator blade rows 50 flows into the multiple inner flow passages 37 that exist for each of the multiple stator blade rows 50. Since the number of the multiple inner flow passages 37 that exist for each of the multiple stator blade rows 50 is smaller than the number of stator blades 51 that each stator blade row 50 has, the flow rate of the drain flowing in one inner flow passage 37 is greater than the flow rate of the drain flowing in one drain transfer flow passage 65 that exists for each of the multiple stator blades 51.

[0055] The drain that flows into one inner flow passage 37 for each of the plurality of rotor blade rows 12 flows into one interrow collecting flow passage 38 that is in communication with this one inner flow passage 37. The drain from one inner flow passage 37 for each of the plurality of rotor blade rows 12 flows into this one interrow collecting flow passage 38. For this reason, the flow rate of the drain flowing in one interrow collecting flow passage 38 is greater than the flow rate of the drain flowing in one inner flow passage 37.

[0056] The drainage water that has flowed into one of the interrow collecting passages 38 flows into one of the outer discharge passages 39 that is in communication with this one of the interrow collecting passages 38. The drainage water that has flowed into this outer discharge passage 39 is discharged from an outlet 39o of the outer discharge passage 39 that opens on the outer peripheral surface 31o of the first blade ring 30a, into a space on the outer circumferential side of the first blade ring 30a and on the inner circumferential side of the inner casing 21. The drainage water that has been discharged into this space flows within this space and flows into the condenser C.

[0057] As described above, the drain collected in the drain collection grooves 61 of each of the multiple stator blades 51 ultimately flows into the condenser C. This flow of drain is basically caused by the pressure difference between the pressure in the steam flow path 17 on the inner periphery of the blade ring 30 and the pressure on the outer periphery of the blade ring 30. For this reason, there is a possibility that some of the steam in the steam flow path 17 will also be discharged to the outer periphery of the blade ring 30 via the flow path through which drain flows. If some of the steam in the steam flow path 17 is discharged to the outer periphery of the blade ring 30 via the flow path through which drain flows, the flow rate of steam that rotates the rotor 10 decreases, and the efficiency of the steam turbine decreases.

[0058] In this embodiment, as described above, the flow rate of the drainage water captured in the drain collection grooves 61 of each of the plurality of stator blades 51 gradually increases as the drainage water passes through the plurality of flow passages and is discharged to the outer periphery of the blade ring 30. Therefore, this flow of drainage water inhibits the discharge of steam to the outer periphery of the blade ring 30. Therefore, in this embodiment, the amount of steam in the steam flow passage 17 that passes through the flow passage through which the drainage water flows can be reduced, and a decrease in steam turbine efficiency can be suppressed.

[0059] As described above, the stator vane segment VS in this embodiment has a flow path that can discharge the drain in the steam flow path 17 to the outer periphery of the blade ring 30, thereby suppressing wet loss due to the drain and reducing the performance degradation of the steam turbine. Furthermore, in this embodiment, the drain transfer groove 62 is formed in the first side surface 59a of the outer shroud 55 and is used as the drain transfer flow path 65. Therefore, it is not necessary to form a drain transfer flow path between multiple stator vane rows 50 in the axial direction Da. Therefore, in this embodiment, the distance between multiple stator vane rows 50 in the axial direction Da can be shortened. Moreover, in this embodiment, one blade ring 30 holds multiple stator vane rows 50. Therefore, in this embodiment, the dimension of the steam turbine in the axial direction Da can be reduced.

[0060] That is, in this embodiment, the steam turbine can be made more compact while maintaining its performance.

[0061] In this embodiment, the first stator vane row is the second-stage stator vane row 50b, the second stator vane row is the third-stage stator vane row 50c, and the third stator vane row is the fourth-stage stator vane row 50d. However, the first stator vane row, the second stator vane row, and the third stator vane row may be composed of three stator vane rows 50 adjacent to each other in the axial direction Da, among the first-stage stator vane row 50a to the fifth-stage stator vane row 50e in this embodiment. That is, for example, in this embodiment, the first stator vane row may be the first-stage stator vane row 50a, the second stator vane row may be the second-stage stator vane row 50b, and the third stator vane row may be the third-stage stator vane row 50c, or the first stator vane row may be the third-stage stator vane row 50c, the second stator vane row may be the fourth-stage stator vane row 50d, and the third stator vane row may be the fifth-stage stator vane row 50e.

[0062] "First variant of the wing ring" A first modified example of the first blade ring in the above embodiment will be described in detail with reference to FIGS.

[0063] Similar to the first blade ring 30a in the above embodiment, the first blade ring 30xa in this modified example has an inner circumferential surface 31i, an outer circumferential surface 31o, blade grooves 32 into which the outer shrouds 55 of the multiple stator blade rows 50 held by this first blade ring 30xa fit, and a drain discharge passage 35x. However, the drain discharge passage 35x of the first blade ring 30xa in this modified example is different from the drain discharge passage 35 of the first blade ring 30a in the above embodiment.

[0064] The drain discharge flow path 35x in this modification has a plurality of annular flow paths 36 and a plurality of outer discharge flow paths 39x, similar to the drain discharge flow path 35 in the above embodiment. However, the drain discharge flow path 35x in this modification does not have the plurality of inner flow paths 37 and the plurality of inter-row collecting flow paths 38 of the drain discharge flow path 35 in the above embodiment.

[0065] Similar to the multiple annular flow paths 36 in the above embodiment, the multiple annular flow paths 36 in this modification are all flow paths annular about the axis Ar. Similar to the above embodiment, the multiple annular flow paths 36 include a second-stage annular flow path 36b, a third-stage annular flow path 36c, a fourth-stage annular flow path 36d, and a fifth-stage annular flow path 36e.

[0066] The multiple outer discharge passages 39x in this modified example extend in the radial direction Dr and open at the outer peripheral surface 31o of the first blade ring 30xa, similar to the multiple outer discharge passages 39 in the above embodiment. The multiple outer discharge passages 39x in this modified example include multiple second-stage outer discharge passages 39xb connected to the second-stage annular passage 36b, multiple third-stage outer discharge passages 39xc connected to the third-stage annular passage 36c, multiple fourth-stage outer discharge passages 39xd connected to the fourth-stage annular passage 36d, and multiple fifth-stage outer discharge passages 39xe connected to the fifth-stage annular passage 36e.

[0067] The number of outer exhaust passages 39x for each of the plurality of annular passages 36 is, for example, less than 10, which is less than the number of the plurality of stator blades 51 that one stator blade row 50 for one annular passage 36 has.

[0068] Drain flows into the second-stage annular flow passage 36b from the drain transfer flow passages 65 of each of the plurality of stator blades 51 in the second-stage stator blade row 50b. The drain that flows into the second-stage annular flow passage 36b flows into the plurality of second-stage outer discharge flow passages 39xb. The drain that flows into the plurality of second-stage outer discharge flow passages 39xb is discharged from outlets 39o of the second-stage outer discharge flow passages 39xb, which open on the outer peripheral surface 31o of the first blade ring 30xa, into a space on the outer circumferential side of the first blade ring 30xa and on the inner circumferential side of the inner casing 21. The drain that flows into this space flows through this space and flows into the condenser C. In the same manner as above, the drain that flows into the other annular flow passages 36 is also discharged into a space on the outer circumferential side of the first blade ring 30xa and on the inner circumferential side of the inner casing 21.

[0069] As described above, the number of outer discharge passages 39x for each of the multiple annular passages 36 is smaller than the number of multiple stator blades 51 (= the number of drain transfer passages 65) that one stator blade row 50 has for one annular passage 36. Therefore, the flow rate of drain flowing through one outer discharge passage 39x is greater than the flow rate of drain flowing through one drain transfer passage 65. Therefore, in this modified example, as in the above embodiment, the amount of steam in the steam passage 17 that is discharged to the outer periphery of the blade ring 30 via the passage through which the drain flows can be reduced, and a decrease in steam turbine efficiency can be suppressed.

[0070] Furthermore, the drain discharge passage 35x in this modified example has a simpler configuration than the drain discharge passage 35 in the above embodiment. Therefore, the first blade ring 30xa having the drain discharge passage 35x in this modified example can be manufactured at a lower cost than the first blade ring 30a having the drain discharge passage 35 in the above embodiment.

[0071] "Second variant of the wing ring" A second modified example of the first blade ring in the above embodiment will be described in detail with reference to FIG.

[0072] Similar to the first blade ring 30a in the above embodiment, the first blade ring 30ya in this modified example has an inner circumferential surface 31i, an outer circumferential surface 31o, blade grooves 32 into which the outer shrouds 55 of the multiple stator vane rows 50 held by this first blade ring 30ya fit, and a drain discharge passage 35y. However, the drain discharge passage 35y of the first blade ring 30ya in this modified example is different from the drain discharge passage 35 of the first blade ring 30a in the above embodiment.

[0073] Similar to the drain discharge flow path 35 in the above embodiment, the drain discharge flow path 35y in this modification has an annular flow path 36, an inner flow path 37, an inter-row collecting flow path 38, and an outer discharge flow path 39. However, unlike the number of outer discharge flow paths 39 of the drain discharge flow path 35 in the above embodiment, the number of inner flow paths 37, the number of inter-row collecting flow paths 38, and the number of outer discharge flow paths 39 of the drain discharge flow path 35y in this modification are all one. The inner flow paths 37, the inter-row collecting flow paths 38, and the outer discharge flow paths 39 in this modification are all disposed directly below the axis Ar.

[0074] The number of outer discharge passages 39 of the drain discharge passage 35y in this modification is smaller than the number of outer discharge passages 39 of the drain discharge passage 35 in the above embodiment. Therefore, the flow rate of drain flowing into the outer discharge passages 39 of the drain discharge passage 35y in this modification is increased. Therefore, in this modification, it is possible to reduce the amount of steam in the steam passage 17 that is discharged to the outer peripheral side of the blade ring 30 via the passage through which the drain flows. Furthermore, in this modification, the outer discharge passage 39 is disposed directly below the axis Ar. Therefore, the drain that collects in this outer discharge passage 39 is acted upon by gravity in addition to the pressure difference between the pressure in the steam passage 17 on the inner peripheral side of the blade ring 30 and the pressure on the outer peripheral side of the blade ring 30. Therefore, in this modification, it is possible to improve the drain discharge efficiency in this outer discharge passage 39.

[0075] Although this modification is a modification of the above embodiment, the first modification of the blade ring described above may also be modified in the same manner as this modification. That is, in the first modification of the blade ring, the number of outer exhaust passages 39x for each of the multiple annular passages 36 may be one. In this case, too, it is preferable that one outer exhaust passage 39x is disposed directly below the axis Ar.

[0076] "Modified outer shroud" A modification of the outer shroud in the above embodiment will be described in detail with reference to FIG.

[0077] The drain recovery groove 61 of the outer shroud 55 in the above embodiment is divided into a first drain recovery groove 61a and a second drain recovery groove 61b by the blade body 52. ​​On the other hand, the drain recovery groove 61x of the outer shroud 55x in this modified example has the first drain recovery groove 61a and the second drain recovery groove 61b, but is not divided into the first drain recovery groove 61a and the second drain recovery groove 61b by the blade body 52. ​​In other words, the drain recovery groove 61x in this modified example is located on the axial upstream side Dau of the blade body 52, and the second drain recovery groove 61b is connected to the first drain recovery groove 61a.

[0078] As described above, the second drain collection groove 61b of the drain collection groove 61 may be separated from the first drain collection groove 61a, or the second drain collection groove 61b of the drain collection groove 61x may be connected to the first drain collection groove 61a.

[0079] In the present modification, when the drain recovery groove 61 is located axially upstream Dau of the blade body 52 and the first drain recovery groove 61a and the second drain recovery groove 61b are connected to each other, the pressure distribution within the drain recovery groove 61 is complex, and it is difficult to determine this pressure distribution solely from the position in the circumferential direction Dc relative to the blade body 52. ​​In this modification, the inlet 64i of the second auxiliary transfer channel 64 is located near the leading edge 52f of the blade body 52, even though it is on the circumferential negative pressure side Dc2 of the blade body 52. ​​For this reason, in this modification, it has been confirmed by calculation that the pressure at the inlet 64i of the second auxiliary transfer channel 64 is higher than the pressure at the inlet 63i of the first auxiliary transfer channel 63, which is located on the circumferential positive pressure side Dc1 of the blade body 52. ​​Therefore, in the present modification, when the first drain recovery groove 61a and the second drain recovery groove 61b are connected to each other, the radial position of the outlet of the auxiliary transfer channel needs to be determined based on calculated or measured pressure.

[0080] As described above, when the pressure at the inlet 63i of the first-side auxiliary transfer flow channel 63 is higher than the pressure at the inlet 64i of the second-side auxiliary transfer flow channel 64 by calculation or actual measurement, it is preferable that the outlet 63o of the first-side auxiliary transfer flow channel 63 is located radially inward Dri from the outlet 64o of the second-side auxiliary transfer flow channel 64. Furthermore, when the pressure at the inlet 64i of the second-side auxiliary transfer flow channel 64 is higher than the pressure at the inlet 63i of the first-side auxiliary transfer flow channel 63 by calculation or actual measurement, it is preferable that the outlet 64o of the second-side auxiliary transfer flow channel 64 is located radially inward Dri from the outlet 63o of the first-side auxiliary transfer flow channel 63.

[0081] "Other Modifications" The steam turbine in the above embodiment has a plurality of blade rings 30. However, the number of blade rings 30 may be one.

[0082] The first blade rings 30a, 30xa in the above-described embodiment and modified examples hold five stator blade rows 50. However, the blade ring 30 may hold two or more stator blade rows 50.

[0083] In the above embodiment and each modified example, the first circumferential side Dc1 is the circumferential pressure side, and the second circumferential side Dc2 is the circumferential negative pressure side. However, the first circumferential side Dc1 may be the circumferential negative pressure side, and the second circumferential side Dc2 may be the circumferential positive pressure side. In this case, the drain transfer groove 62 may be formed on the circumferential negative pressure side of the two side surfaces of the outer shroud 55.

[0084] In the above embodiment, the outlet 63o of the first-side auxiliary transfer flow path 63 is positioned radially inward Dri of the outlet 64o of the second-side auxiliary transfer flow path 64. However, when the first-side auxiliary transfer flow path 63 is arranged on the circumferential negative pressure side and the second-side auxiliary transfer flow path 64 is arranged on the circumferential positive pressure side, it is preferable to position the outlet 64o of the second-side auxiliary transfer flow path 64 radially inward Dri of the outlet 63o of the first-side auxiliary transfer flow path 63.

[0085] The outer shroud 55 in the above embodiment has the first auxiliary transfer flow path 63 and the second auxiliary transfer flow path 64. However, depending on the amount of drainage, the outer shroud 55 may have only one of the first auxiliary transfer flow path 63 and the second auxiliary transfer flow path 64, or may not have both auxiliary transfer flow paths.

[0086] The present disclosure is not limited to the embodiments described above, and various additions, modifications, substitutions, partial deletions, etc. are possible within the scope of the conceptual idea and spirit of the present invention as derived from the content defined in the claims and their equivalents.

[0087] "Addendum" The vane segments VS in the above-described embodiment and modified examples can be understood, for example, as follows.

[0088] (1) The stator vane segment VS in the first embodiment is The turbine rotor includes a plurality of stator vane rows 50 including a first stator vane row 50b and a second stator vane row 50c, and blade rings 30a, 30xa, and 30ya that hold the plurality of stator vane rows 50. The plurality of stator vane rows 50 are aligned in an axial direction Da along which an axis Ar extends. Each of the plurality of stator vane rows 50 has a plurality of stator vanes 51 aligned in a circumferential direction Dc relative to the axis Ar. Each of the plurality of stator vanes 51 in each of the plurality of stator vane rows 50 has a blade body 52 extending in a radial direction Dr relative to the axis Ar, and an outer shroud 55, 55x provided on the radially outer side Dro of the radially inner side Dri and the radially outer side Dro of the blade body 52 in the radial direction Dr. The outer shroud 55, 55x has a gas path surface 56 facing the radially inner side Dri, and a first side surface 59a facing the circumferential first side Dc1 of a circumferential first side Dc1 and a circumferential second side Dc2 in the circumferential direction Dc. The blade ring 30a, 30xa, 30ya is annular about the axis Ar. The blade ring 30a, 30xa, 30ya has an inner circumferential surface 31i facing the radially inner side Dri, an outer circumferential surface 31o facing the radially outer side Dro, blade grooves 32 for each of the plurality of stator blade rows 50 recessed from the inner circumferential surface 31i toward the radially outer side Dro and extending in the circumferential direction Dc, and drain discharge flow passages 35, 35x, 35y. The outer shrouds 55, 55x of the plurality of stator vanes 51 in the first stator vane row 50b are fitted into first blade grooves 32b among the blade grooves 32 of each of the plurality of stator vane rows 50. The outer shrouds 55, 55x of the plurality of stator vanes 51 in the second stator vane row 50c are fitted into second blade grooves 32c that are adjacent to the axial downstream side Dad of the blade grooves 32 of each of the plurality of stator vane rows 50, between the axial upstream side Dau and the axial downstream side Dad with respect to the first blade groove 32b in the axial direction Da. The outer shrouds 55, 55x of the plurality of stator vanes 51 in the second stator vane row 50c each have drain recovery grooves 61, 61x and a drain transfer groove 62. The drain recovery grooves 61, 61x are recessed from the gas path surfaces 56 of the outer shrouds 55, 55x toward the radially outer side Dro and extend in the circumferential direction Dc.The drain transfer groove 62 communicates with the drain recovery grooves 61, 61x, is recessed from the first side surface 59a of the outer shroud 55, 55x toward the circumferential second side Dc2, and extends to an edge of the radially outer side Dro of the outer shroud 55, 55x. The drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya communicate with the drain transfer grooves 62 of the outer shrouds 55, 55x of the plurality of stator vanes 51 in the second stator vane row 50c, and open at the outer peripheral surface 31o. Of the plurality of stator vanes 51 included in the second stator vane row 50c, of two stator vanes 51 adjacent to each other in the circumferential direction Dc, the drain transfer groove 62 of the stator vane 51 located on the circumferential second side Dc2 cooperates with the second side surface 59b of the stator vane 51 located on the circumferential first side Dc1 to form a drain transfer passage 65 that can guide the drain from the drain recovery grooves 61, 61x to the drain discharge passages 35, 35x, 35y. The drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya communicate with the drain transfer passage 65 and can discharge the drain from the drain transfer passage 65 to the outer circumferential side of the blade rings 30a, 30xa, 30ya.

[0089] In the stator vane segment VS of this embodiment, a portion of the drain that has passed through the rotor blade row 12 adjacent to the axial upstream side Dau of the second stator vane row 50c can be captured by the drain recovery grooves 61, 61x of each of the plurality of stator vanes 51 of this second stator vane row 50c. A portion of the drain in the drain recovery grooves 61, 61x flows through this drain recovery groove 61, 61x to the circumferential first side Dc1, and another portion of the drain in the drain recovery groove 61, 61x flows through this drain recovery groove 61, 61x to the circumferential second side Dc2. The drain that flows inside the drain collection groove 61, 61x to the circumferential first side Dc1 flows into the drain transfer flow passage 65 connected to the end of the drain collection groove 61, 61x on the circumferential first side Dc1, and the drain that flows inside the drain collection groove 61, 61x to the circumferential second side Dc2 flows into the drain transfer flow passage 65 connected to the end of the drain collection groove 61, 61x on the circumferential second side Dc2. The drain transfer flow passage 65 connected to the end of the drain collection groove 61, 61x on the circumferential first side Dc1 is a flow passage formed by the drain transfer groove 62 formed in the first side surface 59a of the outer shroud 55, 55x in which the drain collection groove 61, 61x is formed, and the second side surface 59b of the outer shroud 55, 55x adjacent to the circumferential first side Dc1 of the outer shroud 55, 55x. Furthermore, the drain transfer passage 65 connected to the end of the drain recovery groove 61, 61x on the circumferential second side Dc2 is a passage formed by the second side surface 59b of the outer shroud 55, 55x on which the drain recovery groove 61, 61x is formed and the drain transfer groove 62 formed in the first side surface 59a of the outer shroud 55, 55x adjacent to the circumferential second side Dc2 of the outer shroud 55, 55x. The drain that flows into each drain transfer passage 65 flows toward the radially outer side Dro within each drain transfer passage 65 and flows into the drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya. The drain that flows into the drain discharge passages 35, 35x, 35y is discharged to the outer periphery of the blade rings 30a, 30xa, 30ya.

[0090] As described above, the stator vane segment VS in this embodiment has a flow path that allows drainage in the steam flow path 17 to be discharged to the outer periphery of the blade ring 30a, 30xa, 30ya. This reduces wet loss due to drainage, thereby preventing a decrease in steam turbine performance. Furthermore, in this embodiment, the drain transfer groove 62 is formed in the first side surface 59a of the outer shroud 55, 55x and is used as the drain transfer flow path 65. This eliminates the need to form the drain transfer flow path 65 between the multiple stator vane rows 50 in the axial direction Da. Therefore, in this embodiment, the distance between the multiple stator vane rows 50 in the axial direction Da can be shortened. Furthermore, in this embodiment, one blade ring 30a, 30xa, 30ya holds multiple stator vane rows 50. Therefore, in this embodiment, the dimension of the steam turbine in the axial direction Da can be reduced.

[0091] That is, in this aspect, the steam turbine can be made more compact while maintaining its performance.

[0092] (2) The stationary vane segment VS in the second embodiment is In the vane segment VS in the first embodiment, the drain recovery grooves 61, 61x are arranged in the outer shrouds 55, 55x on the axial upstream side Dau of the intermediate position of the blade body 52 in the axial direction Da.

[0093] In this embodiment, a portion of the drain that has passed through the rotor blade row 12 adjacent to the axial upstream side Dau of the second stator blade row 50c can be captured in the drain recovery grooves 61, 61x of each of the multiple stator blades 51 that the second stator blade row 50c has before passing through this second stator blade row 50c.

[0094] (3) The stationary vane segment VS in the third embodiment is In the vane segment VS in the first or second embodiment, the groove width at the radially outer edge Dro of the outer shroud 55, 55x in the drain transfer groove 62 is wider than the groove width at the position in the drain transfer groove 62 that is connected to the drain recovery groove 61, 61x.

[0095] In this embodiment, the efficiency of drainage from the drain transfer flow path 65 to the drain discharge flow paths 35, 35x, 35y can be improved.

[0096] (4) The stator vane segment VS in the fourth aspect is In the stator vane segment VS according to any one of the first to third embodiments, the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a first auxiliary transfer passage 63. The drain recovery grooves 61, 61x in the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a first drain recovery groove 61a located on the circumferential first side Dc1 with respect to the blade body 52. ​​The first auxiliary transfer passage 63 has an inlet 63i that opens in a plane that defines the first drain recovery groove 61a and an outlet 63o that opens in a plane that defines the drain transfer groove 62, and is able to guide the drain in the first drain recovery groove 61a into the drain transfer groove 62.

[0097] When there is a large amount of drain in the steam flow path 17, even when the drain already captured in the first drain recovery groove 61a is flowing through the first drain recovery groove 61a toward the circumferential first side Dc1, the drain may be captured in the first drain recovery groove 61a, and the first drain recovery groove 61a may become filled with drain. In this case, the first drain recovery groove 61a is no longer able to capture any more drain, and the drain recovery rate decreases. In this embodiment, because some of the drain flowing through the first drain recovery groove 61a toward the circumferential first side Dc1 flows into the first-side auxiliary transfer flow path 63, it is possible to prevent the first drain recovery groove 61a from being filled with drain and the drain recovery rate from decreasing.

[0098] (5) The stator vane segment VS in the fifth aspect is In the stator vane segment VS according to any one of the first to third aspects, the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a second-side auxiliary transfer passage 64. The drain recovery grooves 61, 61x in the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a second drain recovery groove 61b located on the second circumferential side Dc2 with respect to the blade body 52. ​​The second-side auxiliary transfer passage 64 has an inlet 64i that opens in a plane that defines the second drain recovery groove 61b and an outlet 64o that opens in the second side surface 59b at a position in the axial direction Da at which the drain transfer groove 62 exists, and is capable of directing the drain in the second drain recovery groove 61b onto the second side surface 59b.

[0099] When there is a large amount of drain in the steam flow path 17, even when the drain already captured in the second drain recovery groove 61b is flowing through the second drain recovery groove 61b toward the second circumferential side Dc2, the drain may be captured in the second drain recovery groove 61b, and the second drain recovery groove 61b may become filled with drain. In this case, the second drain recovery groove 61b is unable to capture any more drain, and the drain recovery rate decreases. In this embodiment, a portion of the drain flowing through the second drain recovery groove 61b toward the second circumferential side Dc2 flows into the second-side auxiliary transfer flow path 64, so it is possible to prevent the second drain recovery groove 61b from being filled with drain and the drain recovery rate from decreasing.

[0100] (6) The stator vane segment VS in the sixth aspect is In the stator vane segment VS according to any one of the first to third aspects, the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a first auxiliary transfer passage 63 and a second auxiliary transfer passage 64. The drain recovery grooves 61, 61x in the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the second stator vane row 50c each have a first drain recovery groove 61a located on the circumferential first side Dc1 with respect to the blade body 52, and a second drain recovery groove 61b located on the circumferential second side Dc2 with respect to the blade body 52. The first-side auxiliary transfer flow path 63 has an inlet 63i that opens in a surface that defines the first drain recovery groove 61a and an outlet 63o that opens in a surface that defines the drain transfer groove 62, and is capable of guiding the drain in the first drain recovery groove 61a into the drain transfer groove 62. The second-side auxiliary transfer flow path 64 has an inlet 64i that opens in a position on the second circumferential side Dc2 of the inlet 63i of the first-side auxiliary transfer flow path 63, in the surface that defines the second drain recovery groove 61b, and an outlet 64o that opens in the second side surface 59b at a position in the axial direction Da where the drain transfer groove 62 is located, and is capable of guiding the drain in the second drain recovery groove 61b onto the second side surface 59b.

[0101] When there is a large amount of drain in the steam flow passage 17, even when some of the drain already captured in the first drain recovery groove 61a flows through the first drain recovery groove 61a toward the circumferential first side Dc1 and another portion of the drain flows through the second drain recovery groove 61b toward the circumferential second side Dc2, the drain may be captured by the second drain recovery groove 61b, causing the second drain recovery groove 61b to become filled with drain. In this case, the drain recovery grooves 61, 61x are no longer able to capture the drain, resulting in a decrease in the drain recovery rate. In this embodiment, some of the drain flowing through the first drain recovery groove 61a toward the circumferential first side Dc1 flows into the first-side auxiliary transfer flow passage 63, and some of the drain flowing through the second drain recovery groove 61b toward the circumferential second side Dc2 flows into the second-side auxiliary transfer flow passage 64. This prevents the drain recovery grooves 61, 61x from being filled with drain, thereby preventing a decrease in the drain recovery rate.

[0102] (7) The stationary vane segment VS in the seventh aspect is In the stator vane segment VS according to the sixth aspect, the inlet 63i of the first auxiliary transfer passage 63 is located closer to the circumferential first side Dc1 than the blade body 52. ​​The inlet 64i of the second auxiliary transfer passage 64 is located closer to the circumferential second side Dc2 than the blade body 52. ​​The blade body 52 has a pressure surface 52p that faces one of the circumferential first side Dc1 and the circumferential second side Dc2 and is recessed toward the other side, and a suction surface 52n that faces the other side and protrudes toward the other side, forming a back-to-back relationship with the pressure surface 52p. Of the first auxiliary transfer passage 63 and the second auxiliary transfer passage 64, the outlet 63o of the auxiliary transfer passage 63 located on the one side is located more radially inward Dri than the outlet 64o of the auxiliary transfer passage 64 located on the other side.

[0103] The pressure in the circumferential pressure side, which is on one side in the circumferential direction Dc with respect to the blade body 52, is higher than the pressure in the circumferential negative pressure side, which is on the other side in the circumferential direction Dc with respect to the blade body 52. ​​Therefore, of the first side auxiliary transfer channel 63 and the second side auxiliary transfer channel 64, the pressure of drain in the auxiliary transfer channel 63, in which the inlet 63i is formed on the circumferential pressure side, which is on one side in the circumferential direction Dc with respect to the blade body 52, is higher than the pressure of drain in the auxiliary transfer channel 64, in which the inlet 64i is formed on the circumferential negative pressure side, which is the other side in the circumferential direction Dc with respect to the blade body 52.

[0104] In this embodiment, the outlet 63o of the auxiliary transfer flow channel 63 located on one side in the circumferential direction Dc is located radially inward Dri of the outlet 64o of the auxiliary transfer flow channel 64 located on the other side in the circumferential direction Dc. Therefore, the position where the high-pressure drain from the auxiliary transfer flow channel 63 located on one side in the circumferential direction Dc flows into the drain transfer flow channel 65 is upstream of the drain flow in the drain transfer flow channel 65 relative to the position where the low-pressure drain from the auxiliary transfer flow channel 64 located on the other side in the circumferential direction Dc flows into the drain transfer flow channel 65. Therefore, in this embodiment, the flow of drain in the drain transfer flow channel 65 can be made smooth.

[0105] (8) In the eighth aspect, the stator vane segment VS is In the stator vane segment VS in the sixth embodiment, the second drain recovery groove 61b is connected to the first drain recovery groove 61a.

[0106] (9) In the ninth aspect, the stator vane segment VS is In the stator vane segment VS according to the eighth aspect, when the pressure at the inlet 63i of the first auxiliary transfer passage 63 is higher than the pressure at the inlet 64i of the second auxiliary transfer passage 64, the outlet 63o of the first auxiliary transfer passage 63 is located at the radially inner Dri than the outlet 64o of the second auxiliary transfer passage 64. Furthermore, when the pressure at the inlet 64i of the second auxiliary transfer passage 64 is higher than the pressure at the inlet 63i of the first auxiliary transfer passage 63, the outlet 64o of the second auxiliary transfer passage 64 is located at the radially inner Dri than the outlet 63o of the first auxiliary transfer passage 63.

[0107] When the first drain recovery groove 61a and the second drain recovery groove 61b are connected to each other, the pressure distribution within the drain recovery groove 61 is complex, and it is difficult to determine this pressure distribution solely from the position in the circumferential direction Dc relative to the blade body 52. ​​Therefore, by calculation or actual measurement, the pressure at the inlet 64i of the second-side auxiliary transfer channel 64 is compared with the pressure at the inlet 63i of the first-side auxiliary transfer channel 63 located on the circumferential positive pressure side Dc1 of the blade body 52. ​​Then, of the first-side auxiliary transfer channel 63 and the second-side auxiliary transfer channel 64, the outlet of the auxiliary transfer channel with the higher pressure at its inlet is positioned radially inward Dri of the outlet of the auxiliary transfer channel with the lower pressure at its inlet. As a result, in this embodiment, the position where high-pressure drain from the auxiliary transfer flow path with a high inlet pressure flows into the drain transfer flow path 65 is located upstream of the drain flow in the drain transfer flow path 65 relative to the position where low-pressure drain from the auxiliary transfer flow path with a low inlet pressure flows into the drain transfer flow path 65. Therefore, in this embodiment, the flow of drain in the drain transfer flow path 65 can be made smooth.

[0108] (10) In the tenth aspect, the stator vane segment VS is In the vane segment VS in any one of the fourth embodiment and the sixth to ninth embodiments, the flow path cross-sectional area of ​​the drain transfer flow path 65 is larger than the flow path cross-sectional area of ​​the first side auxiliary transfer flow path 63.

[0109] In this embodiment, when drain is flowing directly into the drain transfer flow path 65 from the drain recovery grooves 61, 61x, even if drain flows into the drain transfer flow path 65 from the first auxiliary transfer flow path 63, the drain can flow smoothly within the drain transfer flow path 65.

[0110] (11) In the eleventh aspect, the stator vane segment VS is In the vane segment VS according to any one of the fifth to ninth aspects, the flow path cross-sectional area of ​​the drain transfer flow path 65 is larger than the flow path cross-sectional area of ​​the second auxiliary transfer flow path 64 .

[0111] In this embodiment, when drain is flowing directly into the drain transfer flow path 65 from the drain recovery grooves 61, 61x, even if drain flows into the drain transfer flow path 65 from the second auxiliary transfer flow path 64, the drain can flow smoothly within the drain transfer flow path 65.

[0112] (12) In the twelfth aspect, the stator vane segment VS is In the vane segment VS in any one of the sixth to ninth embodiments, the flow path cross-sectional area of ​​the drain transfer flow path 65 is larger than the combined flow path cross-sectional area of ​​the first side auxiliary transfer flow path 63 and the flow path cross-sectional area of ​​the second side auxiliary transfer flow path 64.

[0113] In this embodiment, when drain is flowing directly into the drain transfer flow path 65 from the drain recovery grooves 61, 61x, even if drain flows into the drain transfer flow path 65 from the first auxiliary transfer flow path 63 and the second auxiliary transfer flow path 64, the drain can flow smoothly within the drain transfer flow path 65.

[0114] (13) In the thirteenth aspect, the stator vane segment VS is In the stator vane segment VS in any one of the first to twelfth embodiments, the drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya are annular around the axis Ar and have annular passages 36c that communicate with the drain transfer grooves 62 of each of the plurality of stator vanes 51 of the second stator vane row 50c.

[0115] A portion of the steam in the steam flow path 17 may be discharged to the outer periphery of the blade rings 30a, 30xa, and 30ya via the flow path through which condensate flows. If a portion of the steam in the steam flow path 17 is discharged to the outer periphery of the blade rings 30a, 30xa, and 30ya via the flow path through which condensate flows, the flow rate of steam that rotates the rotor 10 decreases, resulting in a decrease in steam turbine efficiency. In this embodiment, the flow rate of condensate flowing in the annular flow path 36 is greater than the flow rate of condensate flowing in the condensate transfer flow path 65 formed by the condensate transfer grooves 62 for each of the stator vanes 51. This flow of condensate therefore inhibits the discharge of steam to the outer periphery of the blade rings 30a, 30xa, and 30ya. Therefore, in this embodiment, the amount of steam in the steam flow path 17 that is discharged to the outer periphery of the blade rings 30a, 30xa, and 30ya via the flow path through which condensate flows can be reduced, thereby suppressing a decrease in steam turbine efficiency.

[0116] (14) In the fourteenth aspect, the stator vane segment VS is In the stator vane segment VS of the thirteenth aspect, the drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya communicate with the annular passage 36c and have one or more outer discharge passages 39, 39x that open on the outer peripheral surface 31o of the blade rings 30a, 30xa, 30ya. The number of the one or more outer discharge passages 39, 39x, 30ya is smaller than the number of the plurality of stator vanes 51 included in the second stator vane row 50c.

[0117] In this embodiment, the flow rate of the drain flowing in the outer discharge passages 39, 39x is greater than the flow rate of the drain flowing in the drain transfer passages 65 formed by the drain transfer grooves 62 for each of the plurality of stator blades 51. Therefore, this flow of drain inhibits the discharge of steam to the outer periphery of the blade rings 30a, 30xa, 30ya. Therefore, in this embodiment, the amount of steam in the steam passage 17 that is discharged to the outer periphery of the blade rings 30a, 30xa, 30ya via the passage through which the drain flows can be reduced, and a decrease in steam turbine efficiency can be suppressed.

[0118] (15) In the fifteenth aspect, the stator vane segment VS is In the stator vane segment VS according to any one of the first to fourteenth aspects, each of the first row outer shrouds 55, 55x, which are the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the first stator vane row 50b, has a drain recovery groove 61, 61x and a drain transfer groove 62. The drain recovery grooves 61, 61x of the first row outer shrouds 55, 55x are recessed from the gas path surface 56 of the first row outer shrouds 55, 55x toward the radially outer side Dro and extend in the circumferential direction Dc. The drain transfer groove 62 of the first row outer shroud 55, 55x communicates with the drain recovery groove 61, 61x of the first row outer shroud 55, 55x, is recessed from the first side surface 59a of the first row outer shroud 55, 55x toward the circumferential second side Dc2, and extends to an edge of the first row outer shroud 55, 55x on the radially outer side Dro. The drain discharge flow passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya communicate with the drain transfer grooves 62 of the first row outer shroud 55, 55x for each of the plurality of stator vanes 51 of the first stator vane row 50b. Of the plurality of stator vanes 51 that the first stator vane row 50b has, of the two stator vanes 51 that are adjacent to each other in the circumferential direction Dc, the drain transfer groove 62 of the stator vane 51 located on the circumferential second side Dc2 cooperates with the second side surface 59b of the stator vane 51 located on the circumferential first side Dc1 to form a drain transfer flow path 65 that can guide drain from the drain recovery grooves 61, 61x of the first row outer shrouds 55, 55x to the drain discharge flow paths 35, 35x, 35y.

[0119] (16) In the sixteenth aspect, the stator vane segment VS is In the stator vane segment VS according to any one of the first to fifteenth aspects, the plurality of stator vane rows 50 include a third stator vane row 50d arranged adjacent to the second stator vane row 50c on the axial downstream side Dad. Each of the third-row outer shrouds 55, 55x, which are the outer shrouds 55, 55x of the plurality of stator vanes 51 included in the third stator vane row 50d, has a drain recovery groove 61, 61x and a drain transfer groove 62. The drain recovery grooves 61, 61x of the third-row outer shrouds 55, 55x are recessed from the gas path surface 56 of the third-row outer shrouds 55, 55x toward the radially outer side Dro and extend in the circumferential direction Dc. The drain transfer groove 62 of the third-row outer shroud 55, 55x communicates with the drain recovery groove 61, 61x of the third-row outer shroud 55, 55x, is recessed from the first side surface 59a of the third-row outer shroud 55, 55x toward the circumferential second side Dc2, and extends to an edge of the third-row outer shroud 55, 55x on the radially outer side Dro. The drain discharge passages 35, 35x, 35y of the blade rings 30a, 30xa, 30ya communicate with the drain transfer groove 62 of the third-row outer shroud 55, 55x for each of the plurality of stator vanes 51 of the third stator vane row 50d. Of the plurality of stator vanes 51 possessed by the third stator vane row 50d, of two stator vanes 51 adjacent to each other in the circumferential direction Dc, the drain transfer groove 62 of the stator vane 51 located on the second circumferential side Dc2 cooperates with the second side surface 59b of the stator vane 51 located on the first circumferential side Dc1 to form a drain transfer flow path 65 that can guide drain from the drain recovery grooves 61, 61x of the third row outer shrouds 55, 55x to the drain discharge flow paths 35, 35x, 35y.

[0120] The steam turbines in the above-described embodiments and modifications can be understood, for example, as follows. (17) In a seventeenth aspect, the steam turbine comprises: The turbine blade includes a stator vane segment VS according to any one of the first to sixteenth aspects, and a rotor 10 rotatable about the axis Ar on the inner peripheral side of the blade rings 30a, 30xa, 30ya. [Explanation of symbols]

[0121] 10: Rotor 11: Rotor shaft 12: Moving blade row 15: Bearing 16: Steam inlet pipe 17: Steam flow path 20: Casing 21: Inner casing 22: Exhaust casing 22s: Exhaust space 23: Diffuser 23s: Diffuser space 27: Exhaust port 30: Wing ring 30a, 30xa, 30ya: First blade ring (simply blade ring) 30b:Second wing ring 30c: Third wing ring 31i: Inner surface 31o: Outer surface 32: Wing groove 32a, 32xa: First stage blade groove 32b: Second stage blade groove (first blade groove) 32c: Third stage blade groove (second blade groove) 32d: Fourth stage blade groove (third blade groove) 32e: Fifth stage wing groove 35, 35x, 35y: Drain discharge flow path 36: Annular flow path 36b: Second stage annular channel 36c: Third stage annular flow passage 36d: Fourth stage annular channel 36e: Fifth stage annular channel 37: Inner flow channel 38: Inter-row collective flow path 39,39x:Outer discharge channel 39xb: Second stage outer discharge flow path 39xc: Third stage outer discharge flow path 39xd: Fourth stage outer discharge flow path 39xe: Fifth stage outer discharge flow path 39o:Exit 50: Stator blade row 50a: First stage stationary blade row 50b: Second stage stator blade row (first stator blade row) 50c: Third stage stator blade row (second stator blade row) 50d: Fourth stage stator blade row (third stator blade row) 50e: Fifth stage stator blade row 51: Static wing 52: Wing body 52f: leading edge 52r: trailing edge 52p: Positive pressure side 52n: Negative pressure side 54: Inner shroud 55,55x: Outer shroud 56: Gas pass surface 57: Anti-gas pass surface 58f:Front 58r: Rear 59a: First aspect 59b:Second side 61, 61x: Drain collection groove 61a: First drain recovery groove 61b: Second drain recovery groove 62: Drain transfer groove 63, 63z: First auxiliary transfer channel 63i: Entrance 63o,63zo:Exit 64, 64z: Second auxiliary transfer channel 64i:Entrance 64o,64zo:Exit 65: Drain transfer flow path C: Condenser S: Steam ST1: First steam turbine section ST2: Second steam turbine section VS: Stator vane segment Ar: Axis line Ap: tube axis Da: Axial direction Da1: First side Da2: Second side Dau: Axis upstream side Dad: Downstream of the axis Dc: Circumferential direction Dc1: Circumferential first side (circumferential pressure side) Dc2: Second circumferential side (negative pressure side) Dr: Radial direction Dri: Radial inner direction Dro: Radial outer side

Claims

1. a plurality of stator blade rows including a first stator blade row and a second stator blade row; a blade ring that holds the plurality of stator blade rows; Equipped with The plurality of stator blade rows are aligned in an axial direction in which an axis extends, Each of the plurality of stator blade rows has a plurality of stator blades arranged in a circumferential direction with respect to the axis, Each of the plurality of stator vanes included in each of the plurality of stator vane rows has a blade body extending in a radial direction relative to the axis, and an outer shroud provided on the radially outer side of a radially inner side and a radially outer side of the blade body in the radial direction, the outer shroud has a gas path surface facing radially inward, a first side surface facing the first circumferential side of a first circumferential side and a second circumferential side in the circumferential direction, and a second side surface facing the second circumferential side, The blade ring has an annular shape centered on the axis line, the blade ring has an inner circumferential surface facing radially inward, an outer circumferential surface facing radially outward, blade grooves recessed from the inner circumferential surface radially outward and extending in the circumferential direction for each of the plurality of stator blade rows, and a drain discharge flow path, the outer shrouds of the plurality of stator vanes in the first stator vane row are fitted into first blade grooves among the blade grooves for each of the plurality of stator vane rows, the outer shrouds of the plurality of stator vanes in the second stator vane row are fitted into second blade grooves adjacent to the axial downstream side of the first blade groove in the axial direction, among the blade grooves for each of the plurality of stator vane rows, and the outer shrouds of the plurality of stator blades included in the second stator blade row each have a drain recovery groove and a drain transfer groove, the drain recovery groove is recessed from the gas path surface of the outer shroud toward the radially outward side and extends in the circumferential direction, the drain transfer groove communicates with the drain recovery groove, is recessed from the first side surface of the outer shroud toward the second circumferential side, and extends to the radially outer edge of the outer shroud; the drain discharge flow passage of the blade ring communicates with the drain transfer grooves of the outer shrouds of the plurality of stator blades in the second stator blade row and opens at the outer peripheral surface, the drain transfer groove of the stator vane located on the second circumferential side among two circumferentially adjacent stator vanes of the second stator vane row cooperates with the second side surface of the stator vane located on the first circumferential side to form a drain transfer flow path that can guide the drain from the drain recovery groove to the drain discharge flow path, the drain discharge flow path of the blade ring is in communication with the drain transfer flow path and is capable of discharging the drain from the drain transfer flow path to the outer circumferential side of the blade ring. Stator vane segment.

2. 2. The vane segment of claim 1, The drain recovery groove is disposed in the outer shroud on the axial upstream side of a middle position of the blade body in the axial direction. Stator vane segment.

3. 2. The vane segment of claim 1, a groove width at the radially outer edge of the outer shroud in the drain transfer groove is wider than a groove width at a position in the drain transfer groove where the drain transfer groove communicates with the drain recovery groove; Stator vane segment.

4. 2. The vane segment of claim 1, each of the outer shrouds of the plurality of stator vanes included in the second stator vane row has a first auxiliary transfer flow passage; the drain recovery grooves in the outer shrouds of the plurality of stator blades included in the second stator blade row all include a first drain recovery groove located on a first side in the circumferential direction with respect to the blade body, the first auxiliary transfer flow path has an inlet opening in a surface defining the first drain recovery groove and an outlet opening in a surface defining the drain transfer groove, and is capable of guiding drain in the first drain recovery groove into the drain transfer groove; Stator vane segment.

5. 2. The vane segment of claim 1, each of the outer shrouds of the plurality of stator blades included in the second stator blade row has a second auxiliary transfer flow passage; the drain recovery grooves in the outer shrouds of the plurality of stator blades included in the second stator blade row all include second drain recovery grooves located on the second circumferential side with respect to the blade body, the second-side auxiliary transfer flow path has an inlet opening in a surface defining the second drain recovery groove and an outlet opening in the second side surface at a position in the axial direction where the drain transfer groove is present, and is capable of directing drain in the second drain recovery groove onto the second side surface. Stator vane segment.

6. 2. The vane segment of claim 1, each of the outer shrouds of the plurality of stator blades included in the second stator blade row has a first auxiliary transfer flow passage and a second auxiliary transfer flow passage; the drain recovery grooves in the outer shrouds of the plurality of stator blades in the second stator blade row each include a first drain recovery groove located on a first circumferential side with respect to the blade body, and a second drain recovery groove located on a second circumferential side with respect to the blade body, the first auxiliary transfer flow path has an inlet opening in a surface defining the first drain recovery groove and an outlet opening in a surface defining the drain transfer groove, and is capable of guiding drain in the first drain recovery groove into the drain transfer groove; the second-side auxiliary transfer flow path has an inlet opening in a surface defining the second drain recovery groove and an outlet opening in the second side surface at a position in the axial direction where the drain transfer groove is present, and is capable of directing drain in the second drain recovery groove onto the second side surface. Stator vane segment.

7. 7. The vane segment of claim 6, the blade body has a pressure surface facing one of the first circumferential side and the second circumferential side and recessed toward the other side, and a suction surface facing the other side and protruding toward the other side, in a back-to-back relationship with the pressure surface, an outlet of the auxiliary transfer flow channel located on one side of the first auxiliary transfer flow channel and the second auxiliary transfer flow channel is located radially inward of an outlet of the auxiliary transfer flow channel located on the other side; Stator vane segment.

8. 7. The vane segment of claim 6, The second drain recovery groove is connected to the first drain recovery groove. Stator vane segment.

9. 9. The vane segment of claim 8, when the pressure at the inlet of the first auxiliary transfer flow channel is higher than the pressure at the inlet of the second auxiliary transfer flow channel, the outlet of the first auxiliary transfer flow channel is located radially inward of the outlet of the second auxiliary transfer flow channel, when the pressure at the inlet of the second auxiliary transfer flow channel is higher than the pressure at the inlet of the first auxiliary transfer flow channel, the outlet of the second auxiliary transfer flow channel is located radially inward of the outlet of the first auxiliary transfer flow channel. Stator vane segment.

10. 5. The vane segment according to claim 4, The cross-sectional area of ​​the drain transfer flow path is larger than the cross-sectional area of ​​the first auxiliary transfer flow path. Stator vane segment.

11. 6. The vane segment according to claim 5, The cross-sectional area of ​​the drain transfer flow path is larger than the cross-sectional area of ​​the second auxiliary transfer flow path. Stator vane segment.

12. 7. The vane segment of claim 6, a flow path cross-sectional area of ​​the drain transfer flow path is larger than a combined flow path cross-sectional area of ​​the first auxiliary transfer flow path and a flow path cross-sectional area of ​​the second auxiliary transfer flow path; Stator vane segment.

13. 2. The vane segment of claim 1, the drain discharge flow path of the blade ring has an annular flow path that is annular around the axis and communicates with the drain transfer grooves of each of the plurality of stator blades in the second stator blade row. Stator vane segment.

14. 14. The vane segment of claim 13, the drain discharge passage of the blade ring has one or more outer discharge passages that communicate with the annular passage and open at the outer peripheral surface of the blade ring, the number of the one or more outer exhaust passages is less than the number of the plurality of stator blades in the second stator blade row; Stator vane segment.

15. 2. The vane segment of claim 1, each of the first row outer shrouds, which are the outer shrouds of the plurality of stator blades included in the first stator blade row, has a drain recovery groove and a drain transfer groove; the drain recovery groove of the first row outer shroud is recessed from the gas path surface of the first row outer shroud toward the radially outer side and extends in the circumferential direction, the drain transfer groove of the first row outer shroud communicates with the drain recovery groove of the first row outer shroud, is recessed from the first side surface of the first row outer shroud toward the second circumferential side, and extends to the radially outer edge of the first row outer shroud; the drain discharge flow passage of the blade ring communicates with the drain transfer groove of the first row outer shroud for each of the plurality of stator blades in the first stator blade row, the drain transfer groove of the stator vane located on the second circumferential side of the plurality of stator vanes in the first stator vane row, among two circumferentially adjacent stator vanes, cooperates with the second side surface of the stator vane located on the first circumferential side to form a drain transfer passage that can guide the drain from the drain recovery groove of the first row outer shroud to the drain discharge passage; Stator vane segment.

16. 2. The vane segment of claim 1, the plurality of stator vane rows includes a third stator vane row arranged adjacent to the second stator vane row on a downstream side of the axis, each of the third row outer shrouds, which are the outer shrouds of the plurality of stator blades included in the third stator blade row, has a drain recovery groove and a drain transfer groove; the drain recovery groove of the third row outer shroud is recessed from the gas path surface of the third row outer shroud toward the radially outer side and extends in the circumferential direction, the drain transfer groove of the third row outer shroud communicates with the drain recovery groove of the third row outer shroud, is recessed from the first side surface of the third row outer shroud toward the second circumferential side, and extends to the radially outer edge of the third row outer shroud; the drain discharge flow passage of the blade ring communicates with the drain transfer groove of the third row outer shroud for each of the plurality of stator blades included in the third stator blade row, the drain transfer groove of the stator vane located on the second circumferential side of the plurality of stator vanes in the third stator vane row, among two circumferentially adjacent stator vanes, cooperates with the second side surface of the stator vane located on the first circumferential side to form a drain transfer passage that can guide the drain from the drain recovery groove of the third row outer shroud to the drain discharge passage; Stator vane segment.

17. A vane segment according to any one of claims 1 to 16; a rotor rotatable about the axis on the inner circumferential side of the blade ring; A steam turbine comprising:

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