Steam turbine

Abstract

To provide a steam turbine capable of inhibiting a structure of a passage for discharging drain from becoming complicated and facilitating work for forming the passage.SOLUTION: A steam turbine includes: a stationary blade including a blade body part and an outer shroud provided on an outer peripheral side of the blade body part; a blade ring having a fitting groove with which an outer peripheral end part of the outer shroud of the stationary blade is fitted; and at least one drain recovery passage formed in the outer shroud of the stationary blade. In the at least one drain recovery passage, an inlet opening is formed on an end surface on one side in the axial direction of the outer shroud and an outlet opening is formed on an outer peripheral surface opposing to the fitting groove of the outer shroud.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to steam turbines. [Background technology]

[0002] For example, steam turbines for geothermal power generation use wet steam as the working fluid, which causes additional wet loss, an energy loss specific to steam turbines that occurs with the generation and growth of water droplets, and this may reduce turbine efficiency. In addition, when water droplets collide with the moving blades of a steam turbine rotating at high speed, the blade surfaces are susceptible to erosion, which may lead to reduced reliability.

[0003] For this reason, drain separation means is sometimes provided in the steam turbine casing to separate the drain from the steam. In Patent Document 1, a space for drain recovery is provided at the outer periphery between the moving blades and the stationary blades, the space having a drain catcher with an inlet portion protruding in the axial direction. Water droplets that accumulate on the blade surface move to the blade tip side by centrifugal force, are scattered from the shroud portion, enter the outer periphery space by centrifugal force, and are discharged outside the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-31723 A Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, drain is discharged by providing a hole for discharging drain on a surface of the blade ring (casing) facing the drain recovery space. On the downstream side of the drain recovery space, the outer peripheral end of the stator vane is fitted into the blade ring, so the direction of the hole for discharging drain is limited to the outer peripheral side. Since the outlet of the hole for discharging drain needs to be connected to a space that is more negatively pressured than the drain recovery space, that is, downstream of the fitting portion in the blade ring where the outer peripheral end of the stator vane is fitted, this leads to a complex structure of the hole for discharging drain, and there is a risk that the work of forming the hole will be difficult.

[0006] In consideration of the above-mentioned circumstances, at least one embodiment of the present disclosure aims to provide a steam turbine that can suppress the complication of the structure of a passage for discharging drain and can facilitate the work of forming the passage. [Means for solving the problem]

[0007] A steam turbine according to at least one embodiment of the present disclosure includes: A stator vane including at least one blade body portion and an outer shroud provided on an outer circumferential side of the at least one blade body portion; a blade ring having a fitting groove into which an outer peripheral end portion of the outer shroud of the stationary vane is fitted; at least one drain recovery passage formed in the outer shroud of the vane, the drain recovery passage having an inlet opening formed in an end face on one axial side of the outer shroud and an outlet opening formed in an outer peripheral surface of the outer shroud facing the fitting groove. Effect of the Invention

[0008] According to at least one embodiment of the present disclosure, a steam turbine is provided that can suppress the complexity of the structure of a passage for discharging drain and can facilitate the work of forming the passage. [Brief description of the drawings]

[0009] [Figure 1]1 is a schematic cross-sectional axial view of a steam turbine according to an embodiment of the present disclosure; FIG. [Diagram 2] 1 is a schematic cross-sectional view along an axial direction in the vicinity of a blade ring of a steam turbine according to an embodiment of the present disclosure; [Diagram 3] 1 is a schematic cross-sectional view along an axial direction in the vicinity of a stator blade of a steam turbine according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of a drain collection passage, a drain collection pocket, and a drain discharge passage of a steam turbine according to an embodiment of the present disclosure, viewed from the upstream axial direction. [Diagram 5] 1 is a schematic cross-sectional view along an axial direction in the vicinity of a stator blade of a steam turbine according to an embodiment of the present disclosure. [Figure 6] 1 is a schematic cross-sectional view along an axial direction in the vicinity of a stator blade of a steam turbine according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a schematic perspective view of an outer shroud of a vane in one embodiment of the present disclosure. [Figure 8] FIG. 2 is a schematic diagram of an outer shroud of a vane according to an embodiment of the present disclosure viewed from the outside in the radial direction. [Figure 9] FIG. 2 is a schematic perspective view of an outer shroud of a vane in one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative positions, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. Note that "along a certain direction" in this disclosure includes not only a certain direction, but also a direction inclined within a range of ±15° relative to the certain direction.

[0011] (Steam turbine) FIG. 1 is a schematic cross-sectional view along the axial direction of a steam turbine 1 according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view along the axial direction of a blade ring of the steam turbine 1 according to an embodiment of the present disclosure. The arrows shown in FIG. 1 indicate the flow of steam ST (main flow). As shown in FIG. 1 and FIG. 2, a steam turbine 1 according to some embodiments includes a rotating rotor 11 rotating about a central axis CA, a plurality of stator blade rows 30, and a blade ring 5 configured to accommodate the rotating rotor 11 and the plurality of stator blade rows 30. The rotating rotor 11 includes a rotating shaft 12 extending along the central axis CA and a plurality of rotor blade rows 20. The steam turbine 1 according to the present disclosure can be suitably applied to a low-pressure turbine having a relatively high wetness. In the following, a steam turbine for geothermal power generation will be described as an example of the steam turbine 1, but the present disclosure can also be applied to a steam turbine for thermal power generation, etc.

[0012] In the illustrated embodiment, the steam turbine 1 further includes a bearing 13 that rotatably supports the rotor 11, as shown in Fig. 1. The bearing 13 is composed of a journal bearing 13A and a thrust bearing 13B.

[0013] Hereinafter, the direction in which the central axis CA of the rotating shaft 12 of the steam turbine 1 extends is defined as the axial direction of the rotating shaft 12, the direction perpendicular to the central axis CA is defined as the radial direction of the rotating shaft 12, and the circumferential direction around the central axis CA is defined as the circumferential direction of the rotating shaft 12. In this disclosure, the axial direction, radial direction, and circumferential direction of the rotating shaft 12 (steam turbine 1) may be simply referred to as the axial direction, radial direction, and circumferential direction, respectively. Also, one side in the axial direction is defined as the upstream side, and the other side in the axial direction is defined as the downstream side. The inner side, which is the side approaching the central axis CA in the radial direction, may be referred to as the inner circumferential side, and the outer side, which is the side away from the central axis CA in the radial direction, may be referred to as the outer circumferential side.

[0014] (wing ring) As shown in Fig. 1, the blade ring 5 is an annular body extending along the circumferential direction, and an intra-blade ring space 50, which is an annular space, is formed between the blade ring 5 and the rotating rotor 11 in the radial direction. The intra-blade ring space 50 has the above-mentioned multiple rotor blade rows 20 and multiple stator blade rows 30 arranged therein, and forms a steam flow path through which steam ST flows from the upstream side to the downstream side in the axial direction. The blade ring 5 may be formed by arranging multiple arc-shaped members extending along the circumferential direction in the circumferential direction. In other words, the blade ring 5 may be divisible into multiple arc-shaped members, and may be formed by assembling the multiple arc-shaped members.

[0015] In the embodiment shown in FIG. 1, the blade ring 5 is formed in a truncated cone shape in which the inner diameter increases from the upstream side to the downstream side in the axial direction. The present disclosure is also applicable to a blade ring 5 in which the inner diameter is constant in the axial direction. In the embodiment shown in FIG. 1, the steam turbine 1 further includes a steam inlet passage forming portion 15 forming a steam inlet passage 14 for introducing steam ST from the upstream side in the axial direction into the blade ring space 50, and a steam exhaust passage forming portion 17 forming a steam exhaust passage 16 for guiding the steam ST exhausted from the blade ring space 50 to the downstream side in the steam flow direction. One side of the steam inlet passage 14 is connected to an inlet formed at the upstream end of the blade ring space 50 in the axial direction. One side of the steam exhaust passage 16 is connected to an outlet formed at the downstream end of the blade ring space 50 in the axial direction, and the other side of the steam exhaust passage 16 is connected to a condenser (not shown).

[0016] (Rotating blade row) Each of the multiple rotor blade rows 20 is disposed at intervals from one another in the axial direction and attached to the rotating shaft 12. Each of the multiple rotor blade rows 20 is composed of multiple rotor blades 2 disposed side by side in the circumferential direction. Each of the multiple rotor blades 2 includes at least one blade main body portion 21 and an outer shroud 22 provided on the outer circumferential side of the at least one blade main body portion 21. The outer shroud 22 is formed in an arc shape extending along the circumferential direction and is adapted to support the at least one blade main body portion 21 disposed on the inner circumferential side. The blade main body portion 21 is airfoil-shaped and extends along the radial direction.

[0017] (Stator blade row) Each of the plurality of stator blade rows 30 is disposed at intervals from one another in the axial direction, and is disposed upstream of the corresponding rotor blade row 20 in the axial direction. Each of the plurality of stator blade rows 30 is supported on the inner peripheral side of the blade ring 5. Each of the plurality of stator blade rows 30 is composed of a plurality of stator blades 3 arranged side by side in the circumferential direction. Each of the plurality of stator blades 3 includes at least one blade main body portion 31 and an outer shroud 4 provided on the outer peripheral side of the at least one blade main body portion 31. The outer shroud 4 is formed in an arc shape extending along the circumferential direction, and is adapted to support at least one blade main body portion 31 arranged on the inner peripheral side. The blade main body portion 31 is airfoil-shaped and extends along the radial direction.

[0018] In the illustrated embodiment, each of the plurality of stator vanes 3 is formed of a metal material such as a Cr-based alloy or a Ni-based alloy. In the illustrated embodiment, each of the plurality of stator vanes 3 further includes an inner shroud 32 provided on the inner circumferential side of at least one blade main body portion 31. The inner shroud 32 is formed in an arc shape extending along the circumferential direction, and is adapted to support at least one blade main body portion 31 arranged on the outer circumferential side.

[0019] (Sealing device) In the illustrated embodiment, the steam turbine 1 further includes a blade side sealing device (blade side seal ring) 9 provided on the outer periphery of the outer shroud 22 of the blade 2 for each of the multiple blade rows 20, and a stator side sealing device (stator side seal ring) 10 provided on the inner periphery of the inner shroud 32 of the stator blade 3 for each of the multiple stator blade rows 30, as shown in FIG. 2.

[0020] (Mating groove) Each of Figures 3, 5, and 6 is a schematic cross-sectional view along the axial direction near the stator blade 3 of the steam turbine 1 according to an embodiment of the present disclosure. Figure 4 is a schematic view of the drain recovery passage 6, the drain recovery pocket 7, and the drain discharge passage 8 of the steam turbine 1 according to an embodiment of the present disclosure, viewed from the upstream side in the axial direction. As shown in Figures 3, 5, and 6, the blade ring 5 has a fitting groove 51 into which the outer circumferential end portion 41 of the outer shroud 4 of the stator blade 3 is fitted. The fitting groove 51 is a recess formed in an inner surface 52 of the blade ring 5 facing the blade ring intra-space 50 so as to be recessed toward the outer circumferential side, and extends along the circumferential direction.

[0021] The outer shroud 4 of the stator vane 3 has an outer peripheral surface 42 which is an end face on the outer side in the radial direction, an upstream end face 43 which is an end face on the upstream side in the axial direction, and a downstream end face 44 which is an end face on the downstream side in the axial direction. The outer peripheral end portion 41 has the outer peripheral surface 42 and outer peripheral edges 431, 441 of the upstream end face 43 and the downstream end face 44. The fitting groove 51 has a bottom surface 511 facing the outer peripheral surface 42, an upstream groove wall surface 512 facing the outer peripheral edge portion 431 of the upstream end face 43, and a downstream groove wall surface 513 facing the outer peripheral edge portion 441 of the downstream end face 44. Each of the bottom surface 511, the upstream groove wall surface 512, and the downstream groove wall surface 513 extends along the circumferential direction.

[0022] In the illustrated embodiment, the outer circumferential surface 42 extends along the circumferential direction. The upstream end surface 43 extends radially from the upstream end of the outer circumferential surface 42 toward the inside in the radial direction. The downstream end surface 44 extends radially from the downstream end of the outer circumferential surface 42 toward the inside in the radial direction. The upstream groove wall surface 512 extends radially from the upstream end of the bottom surface 511 toward the inside in the radial direction. The downstream groove wall surface 513 extends radially from the downstream end of the bottom surface 511 toward the inside in the radial direction.

[0023] 3, 5, and 6, the fitting groove 51 has an upstream recess 514 recessed axially upstream from the upstream groove wall surface 512. The upstream recess 514 extends along the circumferential direction.

[0024] (Caulking materials) The steam turbine 1 further includes a plurality of caulking members 18 each having an L-shaped cross section perpendicular to the circumferential direction. A portion of each of the plurality of caulking members 18 is inserted into the upstream recess 514 and fitted between the upstream recess 514 and the outer circumferential edge portion 431 of the upstream end face 43. Each of the plurality of caulking members 18 is formed in an arc shape extending along the circumferential direction, and is disposed adjacent to one another in the circumferential direction.

[0025] 3, 5 and 6, in the illustrated embodiment, the stator blade 3 is disposed between an upstream blade 2A, which is a blade 2 disposed adjacent to the stator blade 3 on the upstream side in the axial direction, and a downstream blade 2B, which is a blade 2 disposed adjacent to the stator blade 3 on the downstream side in the axial direction. The blade ring space 50 includes an upstream inter-blade space 50A formed between the blade body portion 21 of the upstream blade 2A and the blade body portion 31 of the stator blade 3, a downstream inter-blade space 50B formed between the blade body portion 31 of the stator blade 3 and the blade body portion 21 of the downstream blade 2B, an upstream drain recovery space 50C formed on the outer periphery of the upstream inter-blade space 50A, and a downstream drain recovery space 50D formed on the outer periphery of the downstream inter-blade space 50B.

[0026] The arrows shown in Figures 3, 5, and 6 indicate the flow of drain (drain water) DW. Water droplets deposited on the blade surface of the blade body 21 of the rotor blade 2 move to the tip side (radially outward) of the blade body 21 by centrifugal force, are scattered from the outer shroud 22 of the rotor blade 2, and enter the upstream drain recovery space 50C or the downstream drain recovery space 50D by centrifugal force.

[0027] (Drain collection passage) A steam turbine 1 according to some embodiments includes the above-described stator vane 3, a blade ring 5 having the above-described fitting groove 51, and at least one drain recovery passage 6 formed in an outer shroud 4 of the stator vane 3. As shown in Figures 3, 5, and 6, each drain recovery passage 6 has an inlet opening 61 formed in an end face (upstream end face 43 or downstream end face 44) on one side in the axial direction of the outer shroud 4, and an outlet opening 62 formed in an outer peripheral surface 42 facing the fitting groove 51 of the outer shroud 4.

[0028] 3 and 6, the inlet opening 61 of the drain recovery passage 6 (6A) is formed in a portion facing the upstream drain recovery space 50C of the upstream end face 43. The drain present in the upstream drain recovery space 50C enters the inside of the drain recovery passage 6 (6A) from the inlet opening 61 and is discharged from the outlet opening 62 to the outside of the drain recovery passage 6 (6A).

[0029] 5 and 6, the inlet opening 61 of the drain recovery passage 6 (6B) is formed in a portion facing the downstream drain recovery space 50D of the downstream end face 44. Drain present in the downstream drain recovery space 50D enters the inside of the drain recovery passage 6 (6B) from the inlet opening 61 and is discharged from the outlet opening 62 to the outside of the drain recovery passage 6 (6B).

[0030] As shown in FIG. 6, the at least one drain collection passage 6 described above may include both a drain collection passage 6A and a drain collection passage 6B.

[0031] According to the above configuration, by forming the drain recovery passage 6 in the outer shroud 4, it is possible to suppress the structure of the passage for discharging drain, including the drain recovery passage 6, from becoming complicated, and the work of forming the passage can be made easy. On the other hand, if the passage for discharging drain from the spaces 50C, 50D facing the end faces 43, 44 on one side in the axial direction of the outer shroud 4 is formed only in the blade ring 5, the fitting groove 51 becomes an obstacle when forming the passage, which may lead to the structure of the passage becoming complicated, and the work of forming the passage may become difficult. By forming the inlet opening 61 of the drain recovery passage 6 in the end faces 43, 44 on one side in the axial direction of the outer shroud 4, it is possible to effectively collect drain from the spaces 50C, 50D facing the end faces 43, 44. In addition, by forming the outlet opening 62 of the drain recovery passage 6 on the outer peripheral surface 42 opposite the fitting groove 51, it is possible to prevent the fitting groove 51 from interfering with the formation of a passage for discharging drain connected to the outlet opening 62.

[0032] (Drain collection pocket, drain discharge passage) In a steam turbine 1 according to some embodiments, as shown in Figures 3, 5 and 6, the blade ring 5 described above has at least one drain recovery pocket 7 formed on the bottom surface 511 of the fitting groove 51 and connected to the outlet opening 62 of the at least one drain recovery passage 6 described above, and at least one drain discharge passage 8 connected on one side to the at least one drain recovery pocket 7 for discharging the drain collected in the at least one drain recovery pocket 7.

[0033] In the illustrated embodiment, the at least one drain collection pocket 7 has a concave shape that is concave from the bottom surface 511 toward the outside in the radial direction. The other side of the at least one drain discharge passage 8 is connected to a space downstream of the blade ring space 50 in the steam flow direction and at a lower pressure than the drain collection spaces 50C and 50D. In the embodiment shown in FIG. 2, the other side of the at least one drain discharge passage 8 is connected to the steam discharge passage 16, which is the low-pressure space. In the embodiment shown in FIG. 2, the inlet 81 of the drain discharge passage 8 is formed on the wall surface of the drain collection pocket 7, and the outlet 82 of the drain discharge passage 8 is formed on the outer surface 53 facing the steam discharge passage 16 of the blade ring 5. Due to a pressure difference generated between the drain collection spaces 50C and 50D and the low-pressure space, the drain present in the drain collection spaces 50C and 50D flows through the drain collection passage 6, the drain collection pocket 7, and the drain discharge passage 8 in this order and is discharged to the low-pressure space.

[0034] According to the above configuration, the drain collection pocket 7 can collect the drain guided from the inside of the blade ring 5 via the drain collection passage 6. Then, the drain discharge passage 8 can discharge the drain collected in the drain collection pocket 7. By forming the drain collection passage 6 in the outer shroud 4, the structure of the drain discharge passage 8 can be prevented from becoming complicated, and the work of forming the drain discharge passage 8 can be facilitated.

[0035] As shown in FIG. 2, a drain recovery passage 6 may be formed in each outer shroud 4 of a plurality of (two in the illustrated example) stator vanes 3 arranged at a distance in the axial direction, and a plurality of drain recovery pockets 7 and a plurality of drain discharge passages 8 corresponding to each of the plurality of drain recovery passages 6 may be formed in the blade ring 5.

[0036] (Drain collection ditch) In the steam turbine 1 according to some embodiments, as shown in Fig. 4, the at least one drain recovery pocket 7 described above includes a drain recovery groove 7A extending along the circumferential direction. In the embodiment shown in Fig. 4, the drain recovery groove 7A is formed in an annular shape, but may be formed in an arc shape. In some embodiments, the drain recovery pocket 7 may be a plurality of drain recovery grooves 7A formed in an arc shape extending along the circumferential direction, arranged side by side in the circumferential direction.

[0037] According to the above configuration, by making the drain collection pocket 7 a drain collection groove 7A extending along the circumferential direction, the outlet opening 62 can be connected to the drain collection groove 7A without adjusting the circumferential position of the outlet opening 62 of the drain collection passage 6. Also, by making the drain collection pocket 7 a drain collection groove 7A extending along the circumferential direction, the volume of drain that the drain collection groove 7A can collect via the drain collection passage 6 can be increased.

[0038] In the steam turbine 1 according to some embodiments, as shown in Fig. 4, the at least one drain recovery passage 6 described above includes a plurality of drain recovery passages 6 arranged at positions spaced apart from each other in the circumferential direction. The drain recovery groove 7A described above is configured to connect to the outlet opening 62 of each of the plurality of drain recovery passages 6.

[0039] According to the above configuration, the drain recovery groove 7A can recover the drain guided from the inside of the blade ring 5 through each of the multiple drain recovery passages 6. In this case, the work of forming the drain recovery groove 7A can be made easier than if an individual drain recovery pocket 7 were formed for each of the outlet openings 62 of the multiple drain recovery passages 6.

[0040] The drain collection pocket 7 is not limited to the drain collection groove 7A. For example, the drain collection pocket 7 may be a recessed portion having a circular or elliptical outer periphery formed on the bottom surface 511 and having a diameter larger than that of the outlet opening 62, and may be formed at a circumferential position corresponding to the outlet opening 62 such that the outer periphery overlaps with the outlet opening 62 in the circumferential direction.

[0041] 4, in the steam turbine 1 according to some embodiments, the at least one drain discharge passage 8 includes a plurality of drain discharge passages 8 arranged at positions spaced apart from each other in the circumferential direction. The drain recovery groove 7A is connected to two or more drain discharge passages 8.

[0042] According to the above configuration, the drain can be collected from the drain collection groove 7A by the multiple drain discharge passages 8 connected to the drain collection groove 7A. In this case, the amount of drain collected from the drain collection groove 7A can be increased compared to when one drain discharge passage 8 is connected to the drain collection groove 7A, and accumulation of drain in the drain collection groove 7A can be suppressed.

[0043] In the steam turbine 1 according to some embodiments, as shown in Fig. 4, the at least one drain discharge passage 8 described above includes a plurality of drain discharge passages 8 arranged at positions spaced apart from each other in the circumferential direction. The drain recovery groove 7A described above is connected to two or more drain discharge passages 8. A larger number of drain discharge passages 8 are arranged below the central axis CA of the rotating rotor 11 of the steam turbine 1 compared to above the central axis CA.

[0044] The symbol HL shown in Fig. 4 indicates a horizontal line extending in the horizontal direction and passing through the central axis CA. As shown in Fig. 4, the number of drain discharge passages 8 connected to the drain collection groove 7A below the horizontal line HL is greater than the number of drain discharge passages 8 connected to the drain collection groove 7A above the horizontal line HL. The number of drain discharge passages 8 arranged above and below the central axis CA is not limited to the embodiment shown in Fig. 4.

[0045] According to the above configuration, since drainage liquid tends to accumulate below the central axis CA, by arranging a large number of drainage discharge passages 8 below the central axis CA, the drainage liquid that accumulates below the drainage recovery groove 7A can be effectively discharged.

[0046] 3 and 6, in the steam turbine 1 according to some embodiments, the inlet opening 61 of the at least one drain recovery passage 6 described above is formed in the upstream end face 43 of the outer shroud 4 of the stator blade 3. The blade ring 5 described above has an opposing surface 54 that faces the upstream end face 43 via an axial gap. The inlet opening 61 communicates with an upstream drain recovery space 50C formed between the upstream end face 43 and the opposing surface 54.

[0047] In the illustrated embodiment, the opposing surface 54 extends radially inward from the axially upstream end of the inner surface 52 facing the upstream drain collection space 50C. The inlet opening 61 communicates with the outer periphery of the upstream drain collection space 50C.

[0048] According to the above configuration, water droplets accumulated on the blade surface of the blade main body 21 of the rotor blade 2 are guided to the upstream drain recovery space 50C by centrifugal force. By communicating the inlet opening 61 of the drain recovery passage 6 with the upstream drain recovery space 50C, the drain separated from the steam can be quickly introduced from the upstream drain recovery space 50C to the drain recovery passage 6, so that the drain can be effectively recovered from inside the blade ring 5.

[0049] Each of the multiple rotor blade-side sealing devices 9 has a main body 91 that extends circumferentially and is supported by the blade ring 5, and multiple seal fins 92 that protrude radially inward from the main body 91 and extend circumferentially. The multiple seal fins 92 seal the gap (tip clearance) between the rotor blade 2 and the blade ring 5.

[0050] 3 and 6, a steam turbine 1 according to some embodiments includes a blade-side sealing device 9A (9) provided on the outer periphery of an upstream blade 2A in which the drain recovery passage 6 is disposed axially upstream of a stator vane 3 formed in an outer shroud 4. The blade-side sealing device 9A has a protruding portion 93 that protrudes axially downstream beyond the opposing surface 54. The inlet opening 62 of the drain recovery passage 6 is provided radially outward of the protruding portion 93.

[0051] In the illustrated embodiment, the above-mentioned protrusion 93 is integrally formed with the main body 91 and extends along the circumferential direction. A barb 931 extending radially outward is formed at the tip of the protrusion 93, i.e., the downstream end in the axial direction. The above-mentioned upstream drain recovery space 50C is defined by the upstream end face 43, the opposing surface 54, the inner surface 52 continuing to the opposing surface 54, the caulking member 18, and the protrusion 93.

[0052] According to the above configuration, the protruding portion 93 of the rotor blade side sealing device 9A functions as a drain catcher, and water droplets guided to the upstream drain recovery space 50C can be prevented from escaping from the upstream drain recovery space 50C. By providing the protruding portion 93 functioning as a drain catcher not on the blade ring 5 or the outer shroud 4 of the stator blade 3 but on the rotor blade side sealing device 9A that is easily detachable from the blade ring 5, the rotor blade side sealing device 9A can be removed during maintenance work on the steam turbine 1, and the upstream drain recovery space 50C on the outer periphery side of the protruding portion 93 can be visually confirmed. For example, by removing the rotor blade side sealing device 9A, the caulking member 18 can be visually confirmed, and damage or deterioration of the caulking member 18 can be easily recognized. Such a steam turbine 1 has excellent maintainability.

[0053] (Collection passage gutter) 7 and 9 are schematic perspective views of the outer shroud 4 of the stator vane 3 in an embodiment of the present disclosure. Fig. 8 is a schematic view of the outer shroud 4 of the stator vane 3 in an embodiment of the present disclosure, viewed from the outside in the radial direction. In the steam turbine 1 according to some embodiments, as shown in Figs. 7 and 8, the at least one drain recovery passage 6 described above includes recovery passage side grooves 6C, 6D formed in at least one of the circumferential end faces 45, 46 of the outer shroud 4.

[0054] The above-mentioned inlet opening 61 is formed on one side of the recovery passage grooves 6C and 6D, and the above-mentioned outlet opening 62 is formed on the other side. Each of the recovery passage grooves 6C and 6D is formed, for example, in a U-shaped cross section. The recovery passage groove 6C is a groove formed on an end face 45 on one side in the circumferential direction of the outer shroud 4, and is a groove recessed from the one-side end face 45 to the other side in the circumferential direction. The recovery passage groove 6D is a groove formed on an end face 46 on the other side in the circumferential direction of the outer shroud 4, and is a groove recessed from the other-side end face 46 to one side in the circumferential direction. Note that either one of the recovery passage grooves 6C and 6D may be formed, or both may be formed.

[0055] According to the above configuration, the recovery passage grooves 6C, 6D formed in the circumferential end faces 45, 46 can effectively recover drainage from the spaces 50C, 50D facing one axial end face of the outer shroud 4. Furthermore, the recovery passage grooves 6C, 6D formed in the circumferential end faces 45, 46 can simplify the work of forming the passages compared to the recovery passage side hole 6G (see FIG. 9) formed inside the outer shroud 4.

[0056] (Second collection passage gutter) 7 and 8, in the steam turbine 1 according to some embodiments, the at least one drain recovery passage 6 described above includes recovery passage grooves (first recovery passage grooves) 6C, 6D formed in at least one of the circumferential end faces 45, 46 of the outer shroud 4. The at least one drain recovery passage 6 described above further includes second recovery passage grooves 6E, 6F formed in the circumferential end faces 46 (46A), 45 (45A) of the outer shroud 4 of another stator vane 3 arranged adjacent to the circumferential end faces 45, 46 in which the recovery passage grooves 6C, 6D are formed in the circumferential direction.

[0057] The second recovery passage grooves 6E, 6F have the inlet opening 61 on one side and the outlet opening 62 on the other side. Each of the second recovery passage grooves 6E, 6F has a U-shaped cross section, for example. The second recovery passage groove 6E is a groove formed in the other circumferential end face 46A (46) of the outer shroud 4 of the other stator vane 3 arranged adjacent to the circumferential end face 45 on which the recovery passage groove 6C is formed, and is a groove recessed from the other end face 46A to one side in the circumferential direction. The second recovery passage groove 6F is a groove formed in the one circumferential end face 45A (45) of the outer shroud 4 of the other stator vane 3 arranged adjacent to the circumferential end face 46 on which the recovery passage groove 6D is formed, and is a groove recessed from the one end face 45A to the other side in the circumferential direction. Note that either one of the second recovery passage grooves 6E or 6F may be formed, or both may be formed.

[0058] According to the above configuration, when the recovery passage grooves 6C, 6D and the second recovery passage grooves 6E, 6F are used as passages for recovering drainage, the volume of the passage for recovering the drainage can be made larger than when only the recovery passage grooves 6C, 6D are used, so that the drainage can be effectively recovered from the spaces 50C, 50D facing one axial end face of the outer shroud 4.

[0059] (Recovery passage side hole) 9, in the steam turbine 1 according to some embodiments, the at least one drain recovery passage 6 described above includes a recovery passage side hole 6G formed inside the outer shroud 4. The recovery passage side hole 6G has the inlet opening 61 described above formed on one side and the outlet opening 62 described above formed on the other side. The recovery passage side hole 6G is formed, for example, in a circular or elliptical cross-sectional shape.

[0060] According to the above configuration, the recovery passage side hole 6G formed inside the outer shroud 4 can effectively recover drainage from the spaces 50C, 50D facing one end face of the outer shroud 4 in the axial direction.

[0061] (Drain recovery passage shape) In the steam turbine 1 according to some embodiments, as shown in Figures 3, 5 and 6, the at least one drain recovery passage 6 described above includes a first straight passage section 63 extending axially from the inlet opening 61, and a second straight passage section 64 extending radially from the tip of the first straight passage section 63 to the outlet opening 62.

[0062] According to the above configuration, by forming the drain recovery passage 6 to include the first straight passage portion 63 and the second straight passage portion 64, the structure of the drain recovery passage 6 can be prevented from becoming complicated, and the formation work of the drain recovery passage 6 can be made easy. In particular, when the drain recovery passage 6 including the first straight passage portion 63 and the second straight passage portion 64 is the recovery passage side grooves 6C, 6D, 6E, and 6F formed on the circumferential end faces 45, 45A, 46, and 46B described above, the first straight passage portion 63 and the second straight passage portion 64 can be formed by a single end mill. When the first straight passage portion 63 and the second straight passage portion 64 are formed by a single end mill, the widths of the first straight passage portion 63 and the second straight passage portion 64 are equal to each other. In other words, when the width of the first straight passage portion 63 is 100%, the width of the second straight passage portion 64 satisfies the condition of 95% or more and 105% or less.

[0063] The drain recovery passage 6 is not limited to a shape including the first straight passage portion 63 and the second straight passage portion 64. For example, the drain recovery passage 6 may be configured to connect the inlet opening 61 and the outlet opening 62 in a straight line.

[0064] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements.

[0065] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0066] The contents described in the above-mentioned embodiments can be understood, for example, as follows.

[0067] 1) A steam turbine (1) according to at least one embodiment of the present disclosure includes: A stator vane (3) including at least one blade body portion (31) and an outer shroud (4) provided on an outer circumferential side of the at least one blade body portion (31); a blade ring (5) having a fitting groove (51) into which an outer peripheral end portion (41) of the outer shroud (4) of the stator vane (3) is fitted; and at least one drain recovery passage (6) formed in the outer shroud (4) of the stator vane (3), the drain recovery passage (6) having an inlet opening (61) formed in an end face (upstream end face 43 or downstream end face 44) on one side in the axial direction of the outer shroud (4) and an outlet opening (62) formed in an outer peripheral surface (42) of the outer shroud (4) facing the fitting groove (51).

[0068] According to the above configuration 1), by forming the drain recovery passage (6) in the outer shroud (4), the structure of the passage for discharging the drain, including the drain recovery passage (6), can be prevented from becoming complicated, and the work of forming the passage can be facilitated. By forming the inlet opening (61) of the drain recovery passage (6) in one end face in the axial direction of the outer shroud (4), the drain can be effectively collected from the space facing the end face. In addition, by forming the outlet opening (62) of the drain recovery passage (6) in the outer peripheral surface (42) facing the fitting groove (51), the fitting groove (51) can be prevented from interfering with the formation of a passage for discharging the drain connected to the outlet opening (62).

[0069] 2) In some embodiments, the steam turbine (1) according to 1) above, The blade ring (5) is at least one drain recovery pocket (7) formed on a bottom surface (511) of the fitting groove (51) facing the outer peripheral surface (42) of the outer shroud (4) and connected to the outlet opening (62) of the at least one drain recovery passage (6); and at least one drain discharge passage (8) connected at one side to the at least one drain collection pocket (7) for discharging the drain collected in the at least one drain collection pocket (7).

[0070] According to the above configuration 2), the drain collection pocket (7) can collect the drain guided from the inside of the blade ring (5) through the drain collection passage (6). Then, the drain discharge passage (8) can discharge the drain collected in the drain collection pocket (7). By forming the drain collection passage (6) in the outer shroud (4), the structure of the drain discharge passage (8) can be prevented from becoming complicated, and the work of forming the drain discharge passage (8) can be facilitated.

[0071] 3) In some embodiments, the steam turbine (1) according to 2) above, The at least one drain collection pocket (7) includes a drain collection groove (7A) extending along the circumferential direction.

[0072] According to the above configuration 3), by forming the drain collection pocket (7) as the drain collection groove (7A) extending along the circumferential direction, the outlet opening (62) can be connected to the drain collection groove (7A) without adjusting the circumferential position of the outlet opening (62) of the drain collection passage (6). In addition, by forming the drain collection pocket (7) as the drain collection groove (7A) extending along the circumferential direction, the volume of drain that can be collected by the drain collection groove (7A) via the drain collection passage (6) can be increased.

[0073] 4) In some embodiments, the steam turbine (1) according to 3) above, the at least one drain recovery passage (6) includes a plurality of drain recovery passages (6) arranged at positions spaced apart from each other in the circumferential direction, The drain recovery groove (7A) is configured to be connected to the outlet opening (62) of each of the plurality of drain recovery passages (6).

[0074] According to the above configuration 4), the drain recovery groove (7A) can recover the drain guided from the inside of the blade ring (5) through each of the plurality of drain recovery passages (6). In this case, the work of forming the drain recovery groove (7A) can be made easier than if an individual drain recovery pocket (7) were formed for each of the outlet openings (62) of the plurality of drain recovery passages (6).

[0075] 5) In some embodiments, the steam turbine (1) according to any one of 1) to 4) above, The inlet opening (61) is formed in an upstream end face (43) of the outer shroud (4) in the axial direction, the blade ring (5) has an opposing surface (54) that faces the upstream end surface (43) of the outer shroud (4) via an axial gap; The inlet opening (61) communicates with a drain collection space (upstream drain collection space 50C) formed between the upstream end face (43) of the outer shroud (4) and the opposing surface (54).

[0076] According to the above configuration 5), the water droplets accumulated on the blade surface of the rotor blade are guided to the drain recovery space (50C) by centrifugal force. By connecting the inlet opening (61) of the drain recovery passage (6) to the drain recovery space (50C), the drain separated from the steam can be quickly introduced from the drain recovery space (50C) to the drain recovery passage (6), so that the drain can be effectively recovered from the inside of the blade ring (5).

[0077] 6) In some embodiments, the steam turbine (1) according to 5) above, the rotor blade side seal device (9A) is provided on an outer circumferential side of a rotor blade (upstream rotor blade 2A) arranged upstream of the stator blade (3), the rotor blade side seal device (9A) having a protruding portion (93) protruding downstream in the axial direction beyond the opposing surface (54), The inlet opening (62) is provided radially outward of the protrusion (93).

[0078] According to the above configuration 6), the protrusion (93) of the rotor blade side sealing device (9A) functions as a drain catcher, and water droplets guided to the drain recovery space (upstream drain recovery space 50C) can be prevented from escaping from the drain recovery space (50C). By providing the protrusion (93) functioning as a drain catcher not on the blade ring (5) or the outer shroud (4) of the stator blade (3) but on the rotor blade side sealing device (9A) which is easily detachable from the blade ring (5), the rotor blade side sealing device (9A) can be removed during maintenance work on the steam turbine (1), and the drain recovery space (50C) on the outer periphery side of the protrusion (93) can be visually observed. Such a steam turbine (1) has excellent maintainability.

[0079] 7) In some embodiments, the steam turbine (1) according to 3) or 4) above, the at least one drain discharge passage (8) includes a plurality of drain discharge passages (8) arranged at positions spaced apart from each other in the circumferential direction, The drain collection groove (7A) is connected to two or more of the drain discharge passages (8).

[0080] According to the above configuration 7), the drain can be collected from the drain collection groove (7A) by the multiple drain discharge passages (8) connected to the drain collection groove (7A). In this case, the amount of drain collected from the drain collection groove (7A) can be increased compared to the case where one drain discharge passage (8) is connected to the drain collection groove (7A), and accumulation of drain in the drain collection groove (7A) can be suppressed.

[0081] 8) In some embodiments, the steam turbine (1) according to 7) above, A larger number of the drain discharge passages (8) are arranged below a central axis (CA) of a rotating rotor (11) of the steam turbine (1) than above the central axis (CA).

[0082] According to the above configuration 8), since drainage tends to accumulate below the central axis (CA), by arranging a large number of drainage discharge passages (8) below the central axis (CA), the drainage that accumulates below the drain collection groove (7A) can be effectively discharged.

[0083] 9) In some embodiments, the steam turbine (1) according to any one of 1) to 8) above, The at least one drain recovery passage (6) includes a recovery passage side groove (6C, 6D) formed in at least one of the circumferential end faces (45, 46) of the outer shroud (4).

[0084] According to the above configuration 9), the recovery passage grooves (6C, 6D) formed in the circumferential end faces (45, 46) can effectively recover drainage from the spaces (50C, 50D) facing one axial end face of the outer shroud (4). In addition, the recovery passage grooves (6C, 6D) formed in the circumferential end faces (45, 46) can simplify the work of forming the passages, compared with the recovery passage hole (6G) formed inside the outer shroud (4).

[0085] 10) In some embodiments, the steam turbine (1) according to any one of 1) to 8) above, The at least one drain recovery passage (6) includes a recovery passage side hole (6G) formed inside the outer shroud (4).

[0086] According to the above configuration 10), the recovery passage side hole (6G) formed inside the outer shroud (4) makes it possible to effectively recover drainage from the space (50C, 50D) facing one end face in the axial direction of the outer shroud (4).

[0087] 11) In some embodiments, the steam turbine (1) according to 9) above, The at least one drain recovery passage (6) further includes a second recovery passage groove (6E, 6F) formed in a circumferential end face (46A, 45A) of the outer shroud (4) of another stator vane (2) arranged adjacent to the circumferential end face (45, 46) in which the recovery passage groove (6C, 6D) is formed in the circumferential direction.

[0088] According to the above configuration 11), when the recovery passage grooves (6C, 6D) and the second recovery passage grooves (6E, 6F) are used as passages for recovering the drainage, the volume of the passage for recovering the drainage can be made larger than when only the recovery passage grooves (6C, 6D) are used. This makes it possible to effectively recover the drainage from the space (50C, 50D) facing one end face in the axial direction of the outer shroud (4).

[0089] 12) In some embodiments, the steam turbine (1) according to any one of 1) to 11) above, The at least one drain recovery passage (6) is a first straight passage portion (63) extending along the axial direction from the inlet opening (61); and a second straight passage portion (64) extending radially from the tip of the first straight passage portion (63) to the outlet opening (62).

[0090] According to the configuration of 12) above, by making the drain recovery passage (6) have a shape including the first straight passage portion (63) and the second straight passage portion (64), the structure of the drain recovery passage (6) can be prevented from becoming complicated, and the work of forming the drain recovery passage (6) can be facilitated. [Explanation of symbols]

[0091] 1. Steam turbine 2 moving blades 3 Stator blade 4 Outer shroud 5 wing ring 6,6A,6B Drain collection passage 6C, 6D Collection passage gutter 6E, 6F 2nd collection passage drain 6G Recovery passage side hole 7 Drain collection pocket 7A Drain collection ditch 8 Drain discharge passage 9. Rotor blade side seal device 10 Stator blade side seal device 11 Rotor 12 Rotating shaft 13 Bearings 13A Journal bearing 13B Thrust bearing 14 Steam inlet passage 15 Steam introduction passage forming section 16 Steam exhaust passage 17 Steam exhaust passage forming part 18 Caulking materials 20 Moving blade row 30 Stator blade row 31 Wing body 41 Outer edge 42 Outer surface 43 Upstream end face 44 Downstream end face 45,46 Circumferential end face 50 Blade ring space 50A Upstream wing space 50B Downstream interwing space 50C Upstream drain collection space 50D Downstream drain collection space 51 Fitting groove 52 Bottom 53 Exterior 54 Opposite Surface 61 Entrance opening 62 Exit opening 63 1st straight passage section 64 2nd straight passage section CA center axis DW Drain HL horizontal line ST Steam

Claims

1. A stator vane including at least one blade body portion and an outer shroud provided on an outer circumferential side of the at least one blade body portion; a blade ring having a fitting groove into which an outer peripheral end portion of the outer shroud of the stationary vane is fitted; at least one drain recovery passage formed in the outer shroud of the vane, the drain recovery passage having an inlet opening formed in an end face on one side in the axial direction of the outer shroud and an outlet opening formed in an outer peripheral surface of the outer shroud facing the fitting groove, Steam turbine.

2. The blade ring is At least one drain recovery pocket is formed on a bottom surface of the fitting groove facing the outer circumferential surface of the outer shroud and connected to the outlet opening of the at least one drain recovery passage; At least one drain discharge passage, one side of which is connected to the at least one drain collection pocket, for discharging the drain collected in the at least one drain collection pocket. The steam turbine of claim 1 .

3. The at least one drain collection pocket includes a drain collection groove extending along a circumferential direction. The steam turbine of claim 2 .

4. the at least one drain recovery passage includes a plurality of drain recovery passages disposed at positions spaced apart from one another in the circumferential direction, The drain recovery groove is configured to connect to the outlet opening of each of the plurality of drain recovery passages. The steam turbine of claim 3 .

5. The inlet opening is formed in an upstream end surface of the outer shroud in the axial direction, the blade ring has an opposing surface that faces the upstream end surface of the outer shroud with an axial gap therebetween, The inlet opening communicates with a drain recovery space formed between the upstream end surface of the outer shroud and the opposing surface. A steam turbine according to any one of claims 1 to 4.

6. a rotor blade side seal device provided on an outer circumferential side of a rotor blade arranged upstream of the stator blade, the rotor blade side seal device having a protruding portion protruding downstream in the axial direction beyond the opposing surface, The inlet opening is provided radially outward from the protruding portion. The steam turbine of claim 5.

7. the at least one drain passage includes a plurality of drain passages arranged at positions spaced apart from one another in the circumferential direction, The drain collection groove is connected to two or more of the drain discharge passages. The steam turbine according to claim 3 or 4.

8. a larger number of the drain discharge passages are arranged below a central axis of the rotating rotor of the steam turbine than above the central axis; The steam turbine of claim 7.

9. The at least one drain recovery passage includes a recovery passage groove formed in at least one of the circumferential end surfaces of the outer shroud. A steam turbine according to any one of claims 1 to 4.

10. the at least one drain recovery passage includes a recovery passage side hole formed inside the outer shroud. A steam turbine according to any one of claims 1 to 4.

11. the at least one drain recovery passage further includes a second recovery passage groove formed in a circumferential end face of an outer shroud of another stator vane disposed adjacent to the circumferential end face in which the recovery passage groove is formed in the circumferential direction. The steam turbine of claim 9.

12. The at least one drain recovery passage comprises: a first linear passage portion extending from the inlet opening along the axial direction; A second straight passage portion extending radially from a tip end of the first straight passage portion to the outlet opening, A steam turbine according to any one of claims 1 to 4.

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