Stationary blade segment, stationary blade ring, and steam turbine

Abstract

A stationary blade segment according to one embodiment comprises: a first stationary blade and a second stationary blade that are circumferentially adjacent; an outer-ring-side shroud; a groove part that is provided on the inner peripheral surface of the outer-ring-side shroud, that is positioned between a first front surface of the first stationary blade and a second back surface of the second stationary blade, and that extends from the first front surface toward the second back surface; and at least one suctioning part that is provided in the groove part or in contact with the groove part and that communicates with the internal space of the outer-ring-side shroud. Designating the position where the groove part and the first front surface cross as a first crossing position and the position where the groove part and the second back surface cross as a second crossing position, a weighted average position of the at least one suction part is closer to the second crossing position than the first crossing position.

Description

Stationary blade segment, stationary blade ring, and steam turbine

[0001] This application claims priority to Japanese Patent Application No. 2024-021606, filed on February 16, 2024, with the Japan Patent Office, the contents of which are incorporated herein by reference.

[0002] In the low-pressure stage blade cascade of a steam turbine, performance degradation (wet loss) due to drainage generated in wet steam and erosion of the rotor blades caused by the drainage colliding with the rotor blades arranged downstream are likely to occur. For this reason, steam turbines equipped with a mechanism for removing drainage from wet steam have been developed (see, for example, Patent Document 1). For example, the steam turbine described in Patent Document 1 is configured to recover drainage from holes provided at the bottom of drainage recesses (grooves) extending circumferentially on the inner peripheral surface of the blade root ring (outer ring shroud) to a drain chamber, which is a space arranged radially outward of the holes.

[0003] Japanese Patent Application Laid-Open No. 2020-002937

[0004] In the steam turbine described in the above-mentioned patent document, holes for collecting drainage are provided at relatively uniform intervals in the circumferential direction in a drain recess extending in the circumferential direction. However, as a result of intensive studies by the inventors, it was found that the drainage adhering to the inner peripheral surface of the blade root ring tends to flow along the leading edge of the drain recess on the inner peripheral surface of the blade root ring from the pressure surface of one stator vane to the suction surface of the other stator vane, rather than flowing into the drainage recess, due to the influence of a secondary flow of steam flowing between the pressure surface of one stator vane and the suction surface of the other stator vane.

[0005] Therefore, if the holes for collecting the drainage liquid are provided at relatively uniform intervals in the circumferentially extending drainage recess, it may be difficult to improve the efficiency of collecting the drainage liquid from the holes.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure has an object to improve the recovery efficiency of drainage generated in wet steam of a steam turbine.

[0007] (1) A stator vane segment according to at least one embodiment of the present disclosure comprises: a first stator vane; a second stator vane adjacent to the first stator vane; and an outer ring side shroud to which a first airfoil portion of the first stator vane and a second airfoil portion of the second stator vane are attached, wherein a first pressure surface of the first airfoil portion faces a second suction surface of the second airfoil portion; a groove portion provided on an inner peripheral surface of the outer ring side shroud, located between the first pressure surface and the second suction surface, and extending from the first pressure surface toward the second suction surface; and at least one suction portion provided within the groove portion or in contact with the groove portion and communicating with an internal space of the outer ring side shroud, wherein a first intersection position is defined as an intersection position between the groove portion and the first pressure surface when viewed from the blade height direction of the first airfoil portion, or an intersection position between an extension line of the groove portion extended toward the first pressure surface and the first pressure surface, When viewed from the blade height direction of the second airfoil section, the intersection position between the groove section and the second dot section, or the intersection position between the extension line of the groove section extended toward the second dot section and the second dot section, is defined as a second intersection position, and a weighted average position of the at least one suction section, obtained by weighting the center position of each suction section in the direction from the first intersection position toward the second intersection position by the opening area of ​​the suction section, is closer to the second intersection position than the first intersection position.

[0008] (2) In a stator blade ring according to at least one embodiment of the present disclosure, a plurality of stator blade segments having the configuration described in (1) above are arranged in the circumferential direction of the outer ring side shroud.

[0009] (3) A steam turbine according to at least one embodiment of the present disclosure includes the stator blade ring having the configuration described in (2) above.

[0010] According to at least one embodiment of the present disclosure, it is possible to improve the efficiency of recovering drainage generated in wet steam of a steam turbine.

[0011] 5A . A cross-sectional view schematically showing a general configuration of a steam turbine according to some embodiments. A schematic cross-sectional view of a stator vane segment and a casing according to some embodiments, as viewed from the circumferential direction. A diagram for explaining a secondary flow of steam. A cross-sectional view taken along arrows IV-IV in FIG. 5A . A diagram of a stator vane segment according to one embodiment, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram of a stator vane segment according to some other embodiments, as viewed from the radially inner side. A diagram for explaining a weighted average position of an inlet portion. A diagram for explaining grooves, described later, that are inclined with respect to the circumferential direction.

[0012] Several embodiments of the present disclosure will be described below with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are not intended to limit the scope of the present disclosure and are merely illustrative examples. For example, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," and "homogeneous," not only express strict equality, but also express tolerance or differences to the extent that the same function is achieved. For example, expressions expressing shapes such as a square or cylindrical shape not only express shapes such as a square or cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0013] A steam turbine 10 according to this embodiment will be described with reference to Fig. 1. For convenience of description, in Fig. 1 and the following Figs. 2 to 7, the direction in which the axis O of the rotating shaft 11 of the steam turbine 10 extends is referred to as an axial direction Da, the circumferential direction of the axis O of the rotating shaft 11 is referred to as a circumferential direction Dc, and the radial direction of the rotating shaft 11 is referred to as a radial direction Dr. In Fig. 1, the direction in which steam S flows is indicated by an arrow S.

[0014] The steam turbine 10 includes a rotor 14 having a rotating shaft 11 and a plurality of blade groups 13 , a casing 16 , a plurality of stator vane segments 19 , journal bearings 23 , and a thrust bearing 25 .

[0015] The rotating shaft 11 extends in the axial direction Da. Both ends of the rotating shaft 11 are disposed outside the casing 16, and the portion of the rotating shaft 11 located between one end and the other end is housed within the casing 16.

[0016] The blade group 13 is fixed to a surface of the outer periphery of the rotating shaft 11 that is housed within the casing 16. The blade group 13 has a plurality of blades 28 that are arranged at intervals in the circumferential direction Dc of the rotating shaft 11. The plurality of blade groups 13 are arranged at intervals in the axial direction Da.

[0017] The rotor blade 28 has a blade body 31 and a rotor blade shroud 33. The blade body 31 extends from the outer periphery of the rotating shaft 11 toward the radially outward (outward in the radial direction Dr).

[0018] The rotor blade shroud 33 is provided at the tip of the blade main body 31. A contact surface of the rotor blade shroud 33 abuts against a contact surface of another rotor blade shroud 33 arranged at an adjacent position in the circumferential direction Dc.

[0019] In the steam turbine 10 according to some embodiments, a plurality of stator blade segments 19 (described later) are arranged in the circumferential direction Dc to form a stator blade ring 20. The stator blade rings 20 are arranged at intervals in the axial direction Da. The stator blade rings 20 and the rotor blade groups 13 are arranged alternately in the axial direction Da.

[0020] The casing 16 has a casing body 41, a steam supply pipe 42, and a steam exhaust pipe 43. The casing body 41 is a cylindrical member extending in the axial direction Da. The casing body 41 houses a plurality of moving blade groups 13 and a portion of the rotating shaft 11 on which the plurality of moving blade groups 13 are provided. The steam supply pipe 42 is provided on one side of the casing body 41 in the axial direction Da. The steam supply pipe 42 functions as a steam inlet for taking steam S into the casing body 41. The steam exhaust pipe 43 is provided on the other side of the casing body 41 in the axial direction Da. The steam exhaust pipe 43 functions as a steam exhaust port for exhausting steam S to the outside of the casing body 41.

[0021] The plurality of stator vane segments 19 are provided along the inner circumferential surface 41a of the casing body 41. The plurality of stator vane segments 19 are arranged at intervals in the axial direction Da. One group of rotor blades 13 is arranged between each of the stator vane segments 19 adjacent to each other in the axial direction Da. The stator vane segments 19 will be described in detail later.

[0022] The stator vane shroud 57 is provided at the tip of each stator vane 55 (described later). The contact surface of the stator vane shroud 57 abuts against the contact surface of another stator vane shroud 57 that is arranged adjacent to the stator vane shroud 57 in the circumferential direction Dc.

[0023] The journal bearings 23 support both ends of the rotating shaft 11. The journal bearings 23 support a load in the radial direction Dr. The thrust bearing 25 is disposed on only one side of the rotating shaft 11 in the axial direction Da. The thrust bearing 25 supports the rotating shaft 11 from the axial direction Da.

[0024] Steam S is supplied into the casing body 41 through a steam supply pipe 42, and then passes through the gaps between the multiple stator vane segments 19 and the multiple moving blade groups 13 as the rotating shaft 11 rotates, and is discharged outside the casing 16 through a steam exhaust pipe 43.

[0025] (Regarding the stator vane segment 19) A specific configuration of the stator vane segment 19 will be described below with reference to FIGS. 1 to 7. FIG. 2 is a schematic cross-sectional view of a stator vane segment and a casing according to some embodiments, as viewed from the circumferential direction, and corresponds to the cross-section along arrows II-II in FIG. 5B , which will be described later. FIG. 3 is a view of the stator vane segment as viewed from the radially inner side, for explaining the secondary flow of steam, and is a cross-sectional view of the airfoil portions of multiple stator vanes. Note that the internal structure of the stator vane 55 is not shown in FIG. 3. Also, in FIG. 3, arrow D indicates the rotation direction of the rotating shaft 11 shown in FIG. 1. FIG. 4 is a cross-sectional view along arrows IV-IV in FIG. 5A , which will be described later. FIG. 5A is a view of a stator vane segment according to one embodiment, as viewed from the radially inner side, and is a cross-sectional view of the airfoil portions of multiple stator vanes. Note that the internal structure of the stator vane 55 is not shown in FIG. 5A and in FIGS. 5B to 5G and 7 , which will be described later. Figures 5B to 5G are views of stator vane segments according to some other embodiments as viewed from the radially inner side, showing cross sections of the airfoil portions of multiple stator vanes. Figure 6 is a diagram for explaining the weighted average position of the suction portion, which will be described later. Figure 7 is a diagram for explaining grooves, which will be described later, that are inclined with respect to the circumferential direction. Note that in Figures 1 to 7, the same or corresponding components are denoted by the same reference numerals.

[0026] The stator vane segment 19 according to some embodiments includes a blade root ring 53, a plurality of stator vanes 55, and a plurality of stator vane shrouds 57. The stator vane segment 19 according to some embodiments includes an intake portion 70 for sucking drain in a drain groove 62 (described later) into a drain chamber 59 (described later).

[0027] The blade root ring 53 is a ring-shaped member extending in the circumferential direction Dc and is also called an outer ring shroud. As shown in Fig. 2, the blade root ring 53 is fitted to a portion of the inner circumferential surface 41a of the casing body 41 that corresponds to the drain discharge flow path 41A formed in the casing body 41. One end of the drain discharge flow path 41A is exposed from the inner circumferential surface 41a of the casing body 41.

[0028] Fitting holes 53b into which a plurality of stator vanes 55 are fitted at intervals in the circumferential direction Dc are formed in the inner circumferential surface 53a of the blade root ring 53 (see FIG. 4). In the stator vane segment 19 according to some embodiments, the fitting holes 53b penetrate from the inner circumferential surface 53a to a drain chamber 59 (described later). The blade root ring 53 has a blade root ring body 58, a drain chamber 59, a communication hole 61, and a drain groove 62 which is a drain recess.

[0029] The drain chamber 59 is a ring-shaped space formed inside the blade root ring main body 58. The communication hole 61 is located between one end of the drain discharge flow path 41A and the drain chamber 59, and is formed to penetrate from the drain chamber 59 to the outer peripheral surface 53c, which is the outer surface in the radial direction Dr of the blade root ring main body 58. In this way, the communication hole 61 connects one end of the drain discharge flow path 41A and the drain chamber 59.

[0030] The drain grooves 62 are grooves formed so as to be located between adjacent stator blades 55 in the circumferential direction Dc. The drain grooves 62 are arranged on the leading edge 55A sides of adjacent stator blades 55 and extend in the circumferential direction Dc. The drain grooves 62 are grooves that are recessed from the inner circumferential surface 53a of the blade root ring 53 toward the casing body 41, i.e., toward the outside in the radial direction Dr.

[0031] The blade root ring 53 according to some embodiments has the drain groove 62 configured as described above, and is therefore able to collect drainage generated in the wet steam in the drain groove 62. The cross-sectional shape of the drain groove 62 when viewed along its extending direction is rectangular as shown in Fig. 2 , but the groove may have inclined wall surfaces so that the width (left-right direction in Fig. 2 , i.e., the axial direction Da) narrows toward the radially outer side, for example.

[0032] The multiple stator vanes 55 are arranged on the inner circumferential surface 53a of the blade root ring 53 at intervals in the circumferential direction Dc. The multiple stator vanes 55 extend inward in the radial direction Dr from the inner circumferential surface 53a of the blade root ring 53. The stator vanes 55 have an airfoil portion 55F. The airfoil portion 55F has a pressure surface 55a, a suction surface 55b, a leading edge 55A, and a trailing edge 55B. The suction surface 55b is arranged on the opposite side of the pressure surface 55a. The leading edge 55A is arranged upstream in the flow direction of the steam S and connects the pressure surface 55a and the suction surface 55b. The trailing edge 55B is arranged downstream in the flow direction of the steam S and connects the pressure surface 55a and the suction surface 55b. The blade height direction H of the stator vane 55 is the same as the radial direction Dr.

[0033] As described above, in the stator vane segment 19 according to some embodiments, the airfoil portion 55F has an outer end portion on the radial direction Dr fitted into the fitting hole 53b of the blade root ring 53. The airfoil portion 55F is coupled to the blade root ring 53 by the coupling portion 80 with the outer end portion on the radial direction Dr fitted into the fitting hole 53b.

[0034] In the stator vane segment 19 according to some embodiments, the joints 80 are, for example, welds that join the airfoil portion 55F and the blade root ring 53 by welding, i.e., a weld between a first airfoil portion 551F (described later) and the blade root ring 53, and a weld between a second airfoil portion 552F (described later) and the blade root ring 53. The joints 80 are provided between the outer surfaces of the airfoil portion 55F, such as the pressure surface 55a and the suction surface 55b, and the inner circumferential surface 53a of the blade root ring 53. This allows the first airfoil portion 551F and the blade root ring 53, and the second airfoil portion 552F and the blade root ring 53, to be joined by welding.

[0035] 5A, 5B, 5C, 5D, 5G, and 7, the coupling portion 80 is provided around the entire circumference of the airfoil portion 55F without spanning the drain groove 62, i.e., except for the portion intersecting with the drain groove 62. The portion where the coupling portion 80 is not provided so as to not span the drain groove 62 is referred to as an unmounted portion 81. In the embodiment shown in FIGS. 5E and 5F, the coupling portion 80 is provided around the entire circumference of the airfoil portion 55F.

[0036] As described above, in the stator vane segment 19 according to some embodiments, the outer end of the airfoil portion 55F in the radial direction Dr is fitted into the fitting hole 53b of the blade root ring 53, so a gap 71 (see FIG. 4 ) exists between the outer surface of the airfoil portion 55F, such as the pressure surface 55a and the suction surface 55b, and the inner circumferential surface 53a of the blade root ring 53. However, the inner end of this gap 71 in the radial direction Dr is closed by the joint portion 80. In the embodiments shown in FIGS. 5A , 5B , 5C , 5D , 5G , and 7 , the joint portion 80 does not straddle the drain groove 62, so the gap 71 is not covered by the joint portion 80 at the position where the drain groove 62 exists, and the gap 71 is exposed when the inner circumferential surface 53a of the blade root ring 53 is viewed from the inside toward the outside in the radial direction Dr.

[0037] (Regarding Secondary Flow of Steam) With reference to Figure 3, the secondary flow of steam S flowing between adjacent stator vanes 55 in the circumferential direction Dc will be described. Between two adjacent stator vanes 55 in the circumferential direction Dc, the pressure surface 55a of one stator vane 55 faces the suction surface 55b of the other stator vane 55. For ease of explanation, in the following explanation, the one stator vane 55 will be referred to as a first stator vane 551, and the other stator vane 55 will be referred to as a second stator vane 552. In addition, in the following explanation, the airfoil portion 55F of the first stator vane 551 will be referred to as a first airfoil portion 551F, the pressure surface 55a of the first stator vane 551 will be referred to as a first pressure surface 551a, and the suction surface 55b of the first stator vane 551 will be referred to as a first suction surface 551b. Similarly, in the following description, the airfoil portion 55F of the second stator vane 552 will be referred to as the second airfoil portion 552F, the positive pressure surface 55a of the second stator vane 552 will be referred to as the second positive pressure surface 552a, and the negative pressure surface 55b of the second stator vane 552 will be referred to as the second negative pressure surface 552b.

[0038] When steam S flows through the inter-blade passage 94 between the first stator vane 551 and the second stator vane 552, near the inner surface 53a of the blade root ring 53, the secondary flow of steam S flows from near the leading edge 55A of the first airfoil section 551F toward the second negative pressure surface 552b of the second stator vane 552, as shown by arrow 95, crossing the main flow of steam S (not shown).

[0039] Therefore, the drain adhering to the inner surface 53a of the blade root ring 53 is influenced by the secondary flow of the steam S described above and flows from the first positive pressure surface 551a of the first airfoil section 551F toward the second negative pressure surface 552b of the second stator blade 552.

[0040] As a result of careful investigation by the inventors, it was found that the drain adhering to the inner surface 53a of the blade root ring 53 is influenced by the secondary flow of the steam S described above, and tends to flow over the inner surface 53a of the blade root ring 53 along the edge of the drain groove 62 on the leading edge 55A side from the first positive pressure surface 551a of the first airfoil section 551F toward the second negative pressure surface 552b of the second stator vane 552, rather than flowing into the drain groove 62.

[0041] From this, it has been found that when providing an intake portion 70 such as a hole, slit, gap, or the like for sucking the drain in the drain groove 62 into the drain chamber 59, it is desirable to provide the intake portion 70 as close as possible to the second suction surface 552b of the second stator vane 552. In the following description, when describing two stator vanes 55 adjacent to each other in the circumferential direction Dc, one of the stator vanes 55 will be referred to as the first stator vane 551 and the other stator vane 55 will be referred to as the second stator vane 552, as described above.

[0042] Therefore, in the stator vane segment 19 according to some embodiments, as shown in, for example, Figures 5A, 5B, 5C, 5D, 5G, and 7, when the inner circumferential surface 53a of the blade root ring 53 is viewed from the inside toward the outside in the radial direction Dr, the gap 71 that is exposed and in contact with the drain groove 62 is used as an intake portion 70 for sucking the drain in the drain groove 62 into the drain chamber 59.

[0043] Furthermore, in some embodiments of the stator vane segment 19, holes 72 or slits 73 serving as suction portions 70 may be provided in the drain groove 62 in addition to or instead of the gap 71, as shown in, for example, Figures 5B, 5C, 5D, 5E, 5F, 5G, and 7.

[0044] 5B, 5G, and 7, holes 72 are provided in the drain groove 62 in addition to the gap 71. In the embodiment shown in Figures 5E and 5F, holes 72 are provided in the drain groove 62 instead of the gap 71.

[0045] The hole 72 extends radially outward from the bottom surface 62a of the drain groove 62 (see FIGS. 2 and 4 ) and reaches the drain chamber 59. The hole 72 connects the drain groove 62 with the drain chamber 59. The hole 72 is a hole for guiding the drain that has been guided into the drain groove 62 to the drain chamber 59.

[0046] The diameter of the hole 72 is configured to be smaller than the width of the drain groove 62, but may be the same as the width of the drain groove 62. When the hole 72 is provided in the drain groove 62, the number of holes 72 provided may be one or two or more in each inter-blade flow passage 94. The position of the hole 72 in the circumferential direction Dc in the drain groove 62 is desirably provided in a position close to the second suction surface 552b of the second stator vane 552, as described above.

[0047] 5C and 5D , a slit 73 is provided in the drain groove 62 together with the gap 71. In the embodiment shown in Fig. 5C , the slit 73 is provided at a position spaced apart from the gap 71 in the circumferential direction Dc, and in the embodiment shown in Fig. 5D , an end of the slit 73 in the circumferential direction Dc is connected to the gap 71. Although not shown, the slit 73 may be provided in the drain groove 62 instead of the gap 71.

[0048] The slit 73 extends radially outward from the bottom surface 62a of the drain groove 62 (see FIGS. 2 and 4 ) and reaches the drain chamber 59. The slit 73 connects the drain groove 62 with the drain chamber 59. The slit 73 is a slit for guiding the drain that has been guided into the drain groove 62 to the drain chamber 59.

[0049] The dimension of the slit 73 in the width direction of the drain groove 62 is configured to be smaller than the width W1 of the drain groove 62, but may be the same as the width of the drain groove 62. There are no particular restrictions on the dimension of the slit 73 in the extension direction of the drain groove 62, but if it is too large, steam S will be undesirably led to the drain chamber 59. Therefore, it is preferable to set the dimension appropriately from the viewpoint of increasing the amount of drain recovered and reducing the amount of steam S suctioned. Note that the dimension of the slit 73 in the extension direction of the drain groove 62 may be equal to or smaller than the dimension of the slit 73 in the width direction of the drain groove 62.

[0050] When the slits 73 are provided in the drain groove 62, the number of the slits 73 provided may be one or two or more in each inter-blade flow passage 94. The position of the slit 73 in the drain groove 62 in the circumferential direction Dc is desirably provided in a position close to the second suction surface 552b of the second stator vane 552, as described above.

[0051] As described above, in the vane segment 19 according to some embodiments, at least one suction portion 70 may be any one of a hole 72 or a slit 73 provided in the drain groove 62, or a gap 71 provided adjacent to the drain groove 62. This allows the drain to be collected with a relatively simple configuration.

[0052] In the stator vane segment 19 according to some embodiments, at least one suction portion 70 may include the above-described gap 71. The gap 71 may be formed between the blade root ring 53 and the second suction surface 552b of the second airfoil portion 552F. This allows the gap 71 between the outer surface (blade surface) of the base end of the airfoil portion 552F and the fitting hole 53b formed in the blade root ring 53 to be used as the gap 71 for collecting condensate, eliminating the need to separately form a gap 71 for collecting condensate, thereby reducing costs.

[0053] The stator vane segment 19 according to some embodiments may include a coupling portion 80 provided between the first airfoil portion 551F and the blade root ring 53 and between the second airfoil portion 552F and the blade root ring 53. The coupling portion 80 may not be provided between the drain groove 62 and the second suction pressure surface 552b of the second airfoil portion 552F. As a result, the gap 71 between the outer surface (airfoil surface) of the base end of the airfoil portion 551F and the fitting hole 53b formed in the blade root ring 53 is not blocked by the coupling portion 80 between the drain groove 62 and the second suction pressure surface 552b of the second airfoil portion 552F, and therefore the gap 71 between the outer surface (airfoil surface) of the base end of the airfoil portion 55F and the fitting hole 53b formed in the blade root ring 53 can be used as a gap for collecting drainage.

[0054] (Regarding the weighted average position of the suction portion 70) As described above, it is desirable to provide the suction portion 70, i.e., the gap 71, the hole 72, and the slit 73, in a position close to the second suction surface 552b of the second stator vane 552. The position of the suction portion 70 in the stator vane segment 19 according to several embodiments will be described below with reference to Figure 6. When viewed from the blade height direction H of the first airfoil section 551F, the intersection position of the drain groove 62 and the first pressure surface 551a, or the intersection position of the extension line L of the drain groove 62 extended toward the first pressure surface 551a and the first pressure surface 551a, is defined as a first intersection position 91. The second intersection position 92 is the intersection position between the drain groove 62 and the second negative pressure surface 552b when viewed from the blade height direction H of the second blade section 552F, or the intersection position between the extension line L when the drain groove 62 is extended toward the second negative pressure surface 552b and the second negative pressure surface 552b.

[0055] In some embodiments of the stator vane segment 19, the weighted average position xA of the suction portion 70 may be closer to the second intersection position 92 than to the first intersection position 91. Here, the weighted average position xA of the suction portion 70 is a value obtained by weighting the center position x of the suction portion 70 in the circumferential direction Dc by the opening area s of the suction portion 70, and will be described in detail below.

[0056] For example, as shown in Figures 5B and 6, a case will be described in which the suction portion 70 includes one gap 71 and two holes 72. The circumferential position Dc of the first intersection position 91 is set to 0, and the circumferential position Dc of the second intersection position 92 is set to 1. Of the two holes 72, the circumferential position Dc of the center (centroid) of the hole 72 closer to the first intersection position 91 is set to x1, and its opening area is set to s1. Of the two holes 72, the circumferential position Dc of the center (centroid) of the hole 72 farther from the first intersection position 91 is set to x2, and its opening area is set to s2. The circumferential position Dc of the center (centroid) of the gap 71 is set to x3, and its opening area is set to s3. In the example shown in Figure 6, the weighted average position xA of the suction portion 70 is calculated as follows: xA = (x1 x s1 + x2 x s2 + x3 x s3) / (s1 + s2 + s3)

[0057] That is, the positions in the circumferential direction Dc of the centers (centroids) of the n suction portions 70 are denoted by x1, x2, ..., xn, and the opening areas of the n suction portions 70 are denoted by s1, s2, ..., sn. In this case, the weighted average position xA of the suction portions 70 is calculated as follows: xA = (x1 x s1 + x2 x s2 + ... + xn x sn) / (s1 + s2 + ... + sn).

[0058] As described above, in the stator vane segment 19 according to some embodiments, the weighted average position xA of the suction portion 70 may be closer to the second intersection position 92 than to the first intersection position 91. That is, when the circumferential direction Dc position of the first intersection position 91 is set to 0 and the circumferential direction Dc position of the second intersection position 92 is set to 1, the weighted average position xA of the suction portion 70 may be 0.5 or greater. This makes it possible to improve the recovery efficiency of the drainage that tends to flow along the inner circumferential surface 53a of the blade root ring 53, along the leading edge 55A side edge of the drain groove 62, from the first pressure surface 551a of the first airfoil portion 551F toward the second suction surface 552b of the second stator vane 552, as described above.

[0059] Furthermore, in the stator blade ring 20 according to some embodiments, a plurality of the stator blade segments 19 according to some embodiments described above are arranged in the circumferential direction Dc. This makes it possible to provide the stator blade ring 20 that can improve the efficiency of collecting drainage.

[0060] The steam turbine 10 according to the embodiment includes the above-described stator blade ring 20. This allows the efficiency of collecting drain in the steam turbine 10 to be improved.

[0061] It is more preferable that the weighted average position xA of the suction portion 70 is, for example, 0.7 or more.

[0062] 5A to 5G , the extension direction of the drain groove 62 coincides with the circumferential direction Dc. That is, in the embodiments shown in FIGS. 5A to 5G , the angle between the extension direction of the drain groove 62 and the circumferential direction Dc is 0 degrees. To collect the drainage adhering to the inner circumferential surface 53 a of the blade root ring 53, it is desirable to increase the amount of drainage that reaches the edge of the drain groove 62 on the leading edge 55A side. However, if the extension direction of the drain groove 62 differs relatively greatly from the circumferential direction Dc, there is a high possibility that the drainage adhering to the inner circumferential surface 53 a of the blade root ring 53 will flow downstream without reaching the edge of the drain groove 62 on the leading edge 55A side.

[0063] 7 , in the stator vane segment 19 according to some embodiments, the extension direction of the drain groove 62 may differ from the circumferential direction Dc. In this case, in the stator vane segment 19 according to some embodiments, the absolute value of the angle difference Δθ between the extension direction of the drain groove 62 and the circumferential direction Dc may be 20 degrees or less. This causes the extension direction of the drain groove 62 to be relatively aligned with the circumferential direction Dc, thereby increasing the amount of drain that reaches the edge of the drain groove 62 on the leading edge 55A side and improving the drain collection efficiency.

[0064] In addition, in the stator vane segment 19 according to some embodiments, the absolute value of the angle difference Δθ between the extension direction of the drain groove 62 and the circumferential direction Dc may be 10 degrees or less. This causes the extension direction of the drain groove 62 to be more aligned with the circumferential direction Dc, thereby further increasing the amount of drain reaching the edge of the drain groove 62 on the leading edge 55A side, and further improving the drain collection efficiency.

[0065] Furthermore, in the stator vane segment 19 according to some embodiments, the extension direction of the drain grooves 62 may be aligned with the circumferential direction Dc. This can further increase the amount of drainage that reaches the edge of the drain groove 62 on the leading edge 55A side, thereby further improving the drainage collection efficiency. Furthermore, if the extension direction of the drain grooves 62 is aligned with the circumferential direction Dc, the multiple drain grooves 62 facing each of the multiple inter-blade flow passages 94 arranged in the circumferential direction Dc can be aligned in a line in the circumferential direction Dc. Therefore, when machining the drain grooves 62, for example, by cutting, the multiple drain grooves 62 can be machined simultaneously by moving the tool and the blade root ring 53 relative to each other in the circumferential direction Dc. This can significantly reduce the machining cost of the drain grooves 62.

[0066] The present disclosure is not limited to the above-described embodiments and includes modifications of the above-described embodiments and appropriate combinations of these embodiments. One end of the drain groove 62 in the extension direction may reach the coupling portion 80 of the first wing portion 551F, as shown in Figures 5A to 5F, or may be separated from it, as shown in Figure 5G. The other end of the drain groove 62 in the extension direction may reach the fitting hole 53b into which the second wing portion 552F is fitted, as shown in Figures 5A to 5D and 5G. Alternatively, the other end may not reach the fitting hole 53b but may reach the coupling portion 80 of the second wing portion 552F as shown in Figure 5E, or may be separated from the coupling portion 80, as shown in Figure 5F.

[0067] The contents described in each of the above embodiments can be understood, for example, as follows: (1) A stator vane segment 19 according to at least one embodiment of the present disclosure includes a first stator vane 551, a second stator vane 552 adjacent to the first stator vane 551, and an outer ring-side shroud (blade root ring 53) to which a first airfoil portion 551F of the first stator vane 551 and a second airfoil portion 552F of the second stator vane 552 are attached. A first pressure surface (first pressure surface 551a) of the first airfoil portion 551F faces a second suction surface (second suction surface 552b) of the second airfoil portion 552F. The stator vane segment 19 according to at least one embodiment of the present disclosure includes: a groove portion (drain groove 62) that is provided on the inner circumferential surface 53 a of the outer-ring-side shroud (blade root ring 53), that is located between the first pressure surface (first pressure surface 551 a) and the second suction surface (second suction surface 552 b), and that extends from the first pressure surface (first pressure surface 551 a) toward the second suction surface (second suction surface 552 b); and at least one suction portion 70 that is provided within the groove portion (drain groove 62) or in contact with the groove portion (drain groove 62) and that communicates with an internal space (drain chamber 59) of the outer-ring-side shroud (blade root ring 53). When viewed from the blade height direction H of the first airfoil portion 551F, the intersection position of the groove portion (drain groove 62) and the first pressure surface (first positive pressure surface 551a) or the intersection position of an extension line L when the groove portion (drain groove 62) is extended toward the first pressure surface (first positive pressure surface 551a) and the first pressure surface (first positive pressure surface 551a) is defined as a first intersection position 91. When viewed from the blade height direction H of the second airfoil portion 552F, the intersection position of the groove portion (drain groove 62) and the second suction surface (second negative pressure surface 552b) or the intersection position of an extension line L when the groove portion (drain groove 62) is extended toward the second suction surface (second negative pressure surface 552b) and the second suction surface (second negative pressure surface 552b) is defined as a second intersection position 92. The weighted average position xA of at least one suction section 70, obtained by weighting the center position x of each suction section 70 in the direction from the first intersection position 91 to the second intersection position 92 by the opening area s of the suction section 70, is closer to the second intersection position 92 than the first intersection position 91.

[0068] According to the configuration (1) above, the weighted average position xA of at least one suction section 70 is closer to the second intersection position 92 than to the first intersection position 91, thereby improving the recovery efficiency of the drain, which tends to flow as described above.

[0069] (2) In some embodiments, in the configuration described in (1) above, the absolute value of the angle difference Δθ between the extending direction of the groove portion (drain groove 62) and the circumferential direction (circumferential direction Dc) of the outer-ring-side shroud (blade root ring 53) may be 20 degrees or less.

[0070] According to the configuration (2) above, the extension direction of the groove portion (drain groove 62) is relatively aligned with the circumferential direction (circumferential direction Dc) of the outer-ring-side shroud (blade root ring 53). This increases the amount of drainage that reaches the edge of the groove portion (drain groove 62) on the leading edge 55A side, thereby improving the drainage collection efficiency.

[0071] (3) In some embodiments, in the configuration described in (1) above, the absolute value of the angle difference Δθ between the extending direction of the groove portion (drain groove 62) and the circumferential direction (circumferential direction Dc) of the outer-ring-side shroud (blade root ring 53) may be 10 degrees or less.

[0072] According to the configuration (3) above, the extension direction of the groove portion (drain groove 62) is more aligned with the circumferential direction (circumferential direction Dc) of the outer-ring-side shroud (blade root ring 53), so that the amount of drain reaching the edge of the groove portion (drain groove 62) on the leading edge 55A side can be further increased, and the drain collection efficiency can be further improved.

[0073] (4) In some embodiments, in the configuration of (1) above, the extending direction of the groove portion (drain groove 62) may coincide with the circumferential direction (circumferential direction Dc) of the outer ring side shroud (blade root ring 53).

[0074] According to the configuration (4) above, the amount of drainage that reaches the edge of the groove (drain groove 62) on the leading edge 55A side can be further increased, thereby further improving the drainage recovery efficiency. Furthermore, according to the configuration (4) above, the plurality of grooves (drain grooves 62) facing the plurality of inter-blade flow passages 94 arranged in the circumferential direction Dc can be aligned in a line in the circumferential direction Dc. Therefore, when machining the grooves (drain grooves 62), for example, by cutting, the plurality of grooves (drain grooves 62) can be machined simultaneously by moving a tool and the outer-ring-side shroud (blade root ring 53) relative to each other in the circumferential direction Dc. This significantly reduces the machining cost of the grooves (drain grooves 62).

[0075] (5) In some embodiments, in any of the configurations (1) to (4) above, at least one suction portion 70 may be any of a hole 72, a slit 73, or a gap 71 provided adjacent to the groove portion (drain groove 62) provided in the groove portion (drain groove 62).

[0076] According to the above configuration (5), the drain can be collected with a relatively simple configuration.

[0077] (6) In some embodiments, in the configuration of (5) above, at least one suction portion 70 may include the gap 71. The gap 71 may be formed between the outer ring shroud (blade root ring 53) and the second suction surface (second suction surface 552b) of the second airfoil portion 552F.

[0078] According to the configuration of (6) above, the gap 71 between the outer surface (positive pressure surface 55a, negative pressure surface 55b) of the base end of the airfoil portion 55F and the hole (fitting hole 53b) formed in the outer ring side shroud (blade root ring 53) can be used as the gap 71 for collecting condensate, so there is no need to separately form the gap 71 for collecting condensate, thereby reducing costs.

[0079] (7) In some embodiments, in any of the configurations (1) to (6) above, it is preferable to provide a coupling portion 80 provided between the first airfoil portion 551F and the outer-ring-side shroud (blade root ring 53) and between the second airfoil portion 552F and the outer-ring-side shroud (blade root ring 53). It is preferable that no coupling portion 80 is provided between the groove portion (drain groove 62) and the second suction surface (second suction surface 552b) of the second airfoil portion 552F.

[0080] According to the configuration (7) above, the gap 71 between the outer surface (pressure surface 55 a, negative pressure surface 55 b) of the base end of the airfoil portion 55F and the hole (fitting hole 53 b) formed in the outer-ring-side shroud (blade root ring 53) is not blocked by the coupling portion 80 between the groove portion (drain groove 62) and the second back surface (second negative pressure surface 552 b) of the second airfoil portion 552F, so the gap 71 between the outer surface (pressure surface 55 a, negative pressure surface 55 b) of the base end of the airfoil portion 55F and the hole (fitting hole 53 b) formed in the outer-ring-side shroud (blade root ring 53) can be used as a gap for collecting drainage.

[0081] (8) In some embodiments, in the configuration of (7) above, the joint 80 may be a welded portion between the first airfoil portion 551F and the outer race side shroud (blade root ring 53), and a welded portion between the second airfoil portion 552F and the outer race side shroud (blade root ring 53).

[0082] According to the above configuration (8), the first airfoil portion 551F and the outer-ring-side shroud (blade root ring 53) and the second airfoil portion 552F and the outer-ring-side shroud (blade root ring 53) can be joined by welding.

[0083] (9) In at least one embodiment of the present disclosure, the stator blade ring 20 has a plurality of stator blade segments 19 having any one of the configurations (1) to (8) above arranged in the circumferential direction (circumferential direction Dc) of the outer ring side shroud (blade root ring 53).

[0084] According to the configuration (9) above, it is possible to provide the stator blade ring 20 that can improve the efficiency of collecting drainage.

[0085] (10) A steam turbine 10 according to at least one embodiment of the present disclosure includes the stator blade ring 20 having the configuration described in (7) above.

[0086] According to the above configuration (10), the efficiency of collecting drainage in the steam turbine 10 can be improved.

[0087] REFERENCE SIGNS LIST 10 Steam turbine 11 Rotating shaft 19 Stator vane segment 20 Stator vane ring 53 Blade root ring 53a Inner peripheral surface 53b Fitting hole 55 Stator vane 55A Leading edge 55a Pressure surface 55B Trailing edge 55b Suction surface 55F Airfoil section 59 Drain chamber 62 Drain groove 70 Intake section 71 Gap 72 Hole 73 Slit 80 Joint section 81 Uninstalled section 91 First intersection position 92 Second intersection position 94 Inter-blade flow passage 551 First stator vane 551a First pressure surface 551b First suction surface 551F First airfoil section 552 Second stator vane 552a Second pressure surface 552b Second suction surface 552F Second airfoil section

Claims

1. A turbine blade comprising: a first stator vane; a second stator vane adjacent to the first stator vane; and an outer ring side shroud to which a first airfoil portion of the first stator vane and a second airfoil portion of the second stator vane are attached, wherein a first pressure surface of the first airfoil portion faces a second suction surface of the second airfoil portion; a groove portion provided on an inner peripheral surface of the outer ring side shroud, located between the first pressure surface and the second suction surface, and extending from the first pressure surface toward the second suction surface; and at least one suction portion provided within the groove portion or in contact with the groove portion and communicating with an internal space of the outer ring side shroud, wherein a first intersection position is defined as an intersection position between the groove portion and the first pressure surface when viewed from the blade height direction of the first airfoil portion, or an intersection position between an extension line of the groove portion extended toward the first pressure surface and the first pressure surface, a second intersection position is an intersection position between the groove portion and the second suction surface when viewed from the blade height direction of the second airfoil portion, or an intersection position between an extension line of the groove portion extended toward the second suction surface and the second suction surface, and a weighted average position of the at least one suction portion obtained by weighting the center position of each suction portion in the direction from the first intersection position toward the second intersection position by an opening area of ​​the suction portion is closer to the second intersection position than the first intersection position.

2. The vane segment according to claim 1, wherein the absolute value of the angle difference between the extending direction of the groove portion and the circumferential direction of the outer ring side shroud is 20 degrees or less.

3. The vane segment according to claim 1, wherein the absolute value of the angle difference between the extending direction of the groove portion and the circumferential direction of the outer ring side shroud is 10 degrees or less.

4. A stator vane segment according to claim 1, wherein the extending direction of the groove portion coincides with the circumferential direction of the outer ring side shroud.

5. A vane segment according to any one of claims 1 to 4, wherein the at least one suction portion is either a hole or a slit provided within the groove portion, or a gap provided adjacent to the groove portion.

6. A stator vane segment according to claim 5, wherein the at least one suction section includes the gap, and the gap is formed between the outer ring side shroud and a second suction surface of the second airfoil section.

7. A stator vane segment according to any one of claims 1 to 4, comprising: connecting portions provided between the first airfoil portion and the outer ring side shroud, and between the second airfoil portion and the outer ring side shroud, and no connecting portions are provided between the groove portion and the second suction surface of the second airfoil portion.

8. A vane segment according to claim 7, wherein the joint is a welded portion between the first airfoil portion and the outer ring side shroud, and a welded portion between the second airfoil portion and the outer ring side shroud.

9. A stator blade ring, wherein a plurality of stator blade segments according to any one of claims 1 to 4 are arranged in the circumferential direction of the outer ring side shroud.

10. A steam turbine comprising the stator blade ring according to claim 9.

Images