Turbine rotor blade

Abstract

To provide a turbine moving blade capable of reducing cost accompanying replacement of a tip side front edge part.SOLUTION: A turbine rotor blade according to an embodiment includes a blade body portion and a tip-side leading edge portion formed of a material harder than the blade body portion, and the tip-side leading edge portion is installed on the blade body portion such that the tip-side leading edge portion is located on a blade tip side and on a leading edge side in a radial direction of a turbine rotor. The tip side leading edge portion includes a first tip side leading edge member and a second tip side leading edge member installed so as to be aligned with the first tip side leading edge member in the radial direction. The first tip-side leading edge member and the airfoil body are joined by the welded part, and the second tip-side leading edge member and the airfoil body are joined by the welded part, whereas the first tip-side leading edge member and the second tip-side leading edge member are not joined.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a turbine blade. [Background technology]

[0002] The turbine blades installed in the low-pressure section of a steam turbine have a long effective length because they receive expanded steam in a low-temperature, low-pressure steam environment. The tips of turbine blades with a long effective length rotate at high speed. Therefore, the tip-side leading edge, located on the leading edge side of the tip of the turbine blade, is subject to significant damage from the impact of water droplets contained in the steam and is prone to erosion.

[0003] Various techniques have been proposed to prevent erosion of the tip leading edge portion of a turbine blade. For example, it has been proposed to construct the tip leading edge portion of the turbine blade, where erosion occurs, from a material (e.g., a cobalt-based alloy) that is harder than the rest of the blade body. In this case, the turbine blade is constructed by joining the tip leading edge portion made of a cobalt-based alloy to the blade body by welding. Another technique has been proposed, which involves hardening the tip leading edge portion of the turbine blade to increase its hardness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 62-180601 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even in turbine blades in which the tip leading edge is made of a hard material such as a cobalt-based alloy and welded to the blade body, erosion progresses as the operating time increases, making it necessary to replace the tip leading edge.

[0006] Erosion becomes more severe as one approaches the tip of a turbine blade. Therefore, in the past, even if there was a portion of the tip leading edge that was less eroded, if there was a portion that was severely eroded, the entire tip leading edge was replaced. As a result, the cost required for replacing the tip leading edge could be high. Furthermore, when the tip leading edge was made of a hard metal material such as a cobalt-based alloy, the time required for fabricating the tip leading edge could be long.

[0007] Therefore, an object of the present invention is to provide a turbine blade that can reduce costs associated with replacing the leading edge portion on the tip side. [Means for solving the problem]

[0008] A turbine blade according to an embodiment is provided in a turbine rotor of an axial-flow steam turbine and is hit by water droplets contained in steam, which is the working fluid of the steam turbine. The turbine blade according to the embodiment includes a blade body and a tip leading edge portion formed of a material harder than the blade body, and the tip leading edge portion is attached to the blade body so that the tip leading edge portion is located toward the blade tip and toward the leading edge in the radial direction of the turbine rotor. The tip leading edge portion includes a first tip leading edge member and a second tip leading edge member arranged radially alongside the first tip leading edge member. The first tip leading edge member and the blade body and the second tip leading edge member and the blade body are joined by welds, while the first tip leading edge member and the second tip leading edge member are not joined together. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows the overall configuration of a steam turbine 1 in the first embodiment. [Figure 2] FIG. 2 is a perspective view that schematically shows an example of the structure of a portion where the turbine rotor blades 50 are installed on the turbine rotor 30 in the steam turbine 1 of the first embodiment. [Figure 3A]FIG. 3A is an enlarged perspective view of a portion of the turbine rotor blade 50 of the first embodiment. [Figure 3B] FIG. 3B is an enlarged cross-sectional view showing a portion of the turbine rotor blade 50 of the first embodiment. [Figure 4A] FIG. 4A is an enlarged perspective view of a part of a turbine rotor blade 50 according to the second embodiment. [Figure 4B] FIG. 4B is an enlarged cross-sectional view showing a part of the turbine rotor blade 50 according to the second embodiment. [Figure 5] FIG. 5 is an enlarged cross-sectional view showing a part of a turbine rotor blade 50 according to the third embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a part of a turbine rotor blade 50 according to the fourth embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing a part of a turbine rotor blade 50 according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment [A] Steam Turbine 1 Before describing the turbine rotor blade of this embodiment, a steam turbine 1 configured using the turbine rotor blade of this embodiment will be described.

[0011] Fig. 1 is a cross-sectional view schematically showing the overall configuration of a steam turbine 1 according to a first embodiment. In Fig. 1, the longitudinal direction is the vertical direction z, the horizontal direction is the first horizontal direction x, and the direction perpendicular to the paper surface is the second horizontal direction y that is perpendicular to the first horizontal direction x. Fig. 1 shows a longitudinal cross section (xz plane) along the vertical direction z and the first horizontal direction x.

[0012] In this embodiment, the steam turbine 1 is a double-flow low-pressure turbine to which steam that has performed work in a high-pressure turbine (not shown) and an intermediate-pressure turbine (not shown) is supplied as a working medium.

[0013] The steam turbine 1 has an outer casing 10 , an inner casing 20 , and a turbine rotor 30 .

[0014] In the steam turbine 1, the outer casing 10 houses the inner casing 20, and the inner casing 20 houses the turbine rotor 30. The turbine rotor 30 is rotatably supported by a bearing 301 such that the axial center line AX is aligned with the first horizontal direction x.

[0015] The steam turbine 1 is an axial flow type, and a plurality of turbine stages 60, each including a turbine stator blade 40 and a turbine rotor blade 50, are provided inside the inner casing 20 in the axial direction along the axial center line AX.

[0016] In the turbine stage 60, there are multiple turbine stator vanes 40, and the multiple turbine stator vanes 40 are arranged in the rotational direction of the turbine rotor 30 between the diaphragm inner ring 41 and the diaphragm outer ring 43 to form a nozzle diaphragm 45.

[0017] In the turbine stage 60, there are a plurality of turbine rotor blades 50, and the plurality of turbine rotor blades 50 are arranged along the rotation direction RT of the turbine rotor 30. In the turbine rotor 30, the turbine rotor blades 50 are embedded in a rotor disk 31 formed so as to protrude radially from the outer circumferential surface.

[0018] In the steam turbine 1, a steam supply pipe 70 is connected to the inner casing 20, and steam is supplied as a working fluid to the steam supply pipe 70 from outside the outer casing 10. The steam supplied to the steam supply pipe 70 flows sequentially through a plurality of turbine stages 60 inside the inner casing 20. That is, the working fluid flows from the first turbine stage 60 toward the final turbine stage 60, expanding in each turbine stage 60 to perform work. As a result, the turbine rotor 30 rotates about the axial center line AX as its rotation axis, and a generator (not shown) connected to the turbine rotor 30 generates electricity. The blade lengths (radial lengths) of the turbine stator vanes 40 and turbine rotor blades 50 are configured to sequentially increase from the first turbine stage 60 toward the final turbine stage 60.

[0019] In the steam turbine 1, steam that has passed through the final turbine stage 60 passes through the cone section 12 and is discharged from the lower end of the external casing 10. The steam discharged from the external casing 10 is supplied to a condenser (not shown) connected to the steam turbine 1, and is condensed in the condenser to generate condensate.

[0020] [B] Overview of turbine rotor blade 50 Fig. 2 is a perspective view that schematically shows an example of the structure of a portion where turbine rotor blades 50 are installed on the turbine rotor 30 in the steam turbine 1 of the first embodiment. Fig. 2 shows a portion of the turbine rotor blades 50 that constitute the final turbine stage 60.

[0021] 2, a plurality of turbine blades 50 are arranged in the rotation direction RT on the rotor disk 31 of the turbine rotor 30. Here, a plurality of blade implantation grooves T30 extending along the axial direction AD, for example, are formed on the outer peripheral surface of the rotor disk 31. The plurality of blade implantation grooves T30 are formed at intervals in the rotation direction RT of the rotor disk 31.

[0022] In this embodiment, each of the plurality of turbine rotor blades 50 has an effective blade portion 51 and a blade implantation portion 52. The effective blade portion 51 is twisted, for example, in the radial direction RA of the turbine rotor 30 from the blade root side IN to the blade tip side OT.

[0023] The blade implantation portion 52 is provided at the blade root in the blade effective portion 51. The blade implantation portion 52 has, for example, a Christmas tree shape, and is inserted along the axial direction (first horizontal direction x) into the blade implantation groove T30 formed in the rotor disk 31 and fitted therein.

[0024] [C] Details of turbine blades 3A and 3B are enlarged views of a portion of the turbine rotor blade 50 according to the first embodiment. Fig. 3A shows a perspective view of a portion located on the blade tip side OT in the radial direction RA of the turbine rotor 30 (portion A in Fig. 2). Fig. 3B shows a cross-sectional view of the portion located on the blade tip side OT (portion BB in Fig. 3A; a part of the plane defined by the camber line connecting the leading edge LE and the trailing edge TE and the radial direction RA).

[0025] In an embodiment, as shown in Figures 3A and 3B, the turbine rotor blade 50 has a blade main body portion 510 and a tip-side leading edge portion 520, and the tip-side leading edge portion 520 is installed on the blade main body portion 510 to form the blade effective portion 51 (see Figure 2).

[0026] In the turbine rotor blade 50, the tip-side leading edge portion 520 is located on the blade tip side OT in the radial direction RA of the turbine rotor 30 and is located on the side of the leading edge LE. The tip-side leading edge portion 520 is formed of a material harder than the blade main body portion 510. The tip-side leading edge portion 520 is made of, for example, a cobalt-based alloy.

[0027] In this embodiment, the tip-side leading edge portion 520 consists of a first tip-side leading edge member 521 and a second tip-side leading edge member 522, and is arranged so that the first tip-side leading edge member 521 and the second tip-side leading edge member 522 are aligned in the radial direction RA.

[0028] Welds 540 are interposed between the first tip-side leading edge member 521 and the wing main body 510, and between the second tip-side leading edge member 522 and the wing main body 510, and are joined by welding using, for example, a Ni-based alloy as a filler metal.

[0029] In contrast, in this embodiment, the first tip side leading edge member 521 and the second tip side leading edge member 522 are in contact with each other but are not joined together. A boundary BL between the first tip side leading edge member 521 and the second tip side leading edge member 522 is along the axial direction AD of the turbine rotor 30.

[0030] [D] Summary As described above, the turbine rotor blade 50 of this embodiment is provided in the turbine rotor 30 that constitutes the axial flow steam turbine 1, and is hit by water droplets contained in steam. For this reason, the tip-side leading edge 520 of the turbine rotor blade 50 is subject to significant damage from the impact of water droplets contained in steam. However, in the turbine rotor blade 50 of this embodiment, the tip-side leading edge 520 is formed of a material that is harder than the blade main body 510. This makes it possible to prevent erosion of the tip-side leading edge 520 by water droplets contained in steam.

[0031] As the operating time of the steam turbine 1 increases, if erosion progresses in the tip leading edge portion 520, the tip leading edge portion 520 will need to be replaced. As already described, erosion becomes more severe as one approaches the tip of the turbine rotor blade. In this embodiment, the tip leading edge portion 520 has a first tip leading edge member 521 and a second tip leading edge member 522 aligned in the radial direction RA, and the first tip leading edge member 521 and the blade main body 510 are joined together, and the second tip leading edge member 522 and the blade main body 510 are joined together. However, in this embodiment, the first tip leading edge member 521 and the second tip leading edge member 522 are not joined together. Therefore, for example, when erosion progresses in the first tip leading edge member 521 located on the blade tip side OT in the tip leading edge portion 520 and replacement of the first tip leading edge member 521 becomes necessary, it is possible to easily replace only the first tip leading edge member 521 without replacing the second tip leading edge member 522. In other words, it is possible to replace some of the multiple tip leading edge members (first tip leading edge member 521, second tip leading edge member 522) that make up the tip leading edge portion 520 depending on the state of erosion, without replacing the entire tip leading edge portion 520.

[0032] Therefore, in this embodiment, it is possible to reduce the cost required for replacing the tip side leading edge portion 520, and also to shorten the time required for producing the replacement tip side leading edge portion 520.

[0033] In this embodiment, the distal end leading edge portion 520 is described as being made up of two distal end leading edge members (the first distal end leading edge member 521 and the second distal end leading edge member 522), but it may be made up of three or more distal end leading edge members.

[0034] Second Embodiment [A] Details of turbine blades 4A and 4B are enlarged views of a portion of a turbine rotor blade 50 according to a second embodiment. Fig. 4A shows a perspective view of a portion similar to Fig. 3A, and Fig. 4B shows a cross-sectional view of a portion similar to Fig. 3B.

[0035] As shown in Figures 4A and 4B, the turbine rotor blade 50 of this embodiment has stress holes HL formed therein, unlike the turbine rotor blade 50 of the first embodiment (see Figures 3A and 3B). Except for this and related points, this embodiment is similar to the first embodiment. Therefore, explanations of overlapping points will be omitted where appropriate.

[0036] The stress holes HL are through-holes that penetrate between the pressure side and the suction side of the turbine rotor blade 50. Here, the stress holes HL are formed so as to penetrate the boundary BL between the first tip-side leading edge member 521 and the second tip-side leading edge member 522 and the welded portion 540 without penetrating the blade main body 510. The stress holes HL are formed using, for example, a drill.

[0037] [B] Summary As described above, in the turbine rotor blade 50 of this embodiment, the stress holes HL relieve the stress applied to the portion of the boundary BL between the first tip leading edge member 521 and the second tip leading edge member 522 that is located on the blade main body 510 side. Specifically, the load applied to the end of the boundary BL that is located on the weld 540 side is reduced.

[0038] Therefore, in this embodiment, the same effects as in the first embodiment can be obtained, and the above-described configuration of the tip-side leading edge portion 520 can also be applied to turbine rotor blades 50 having a longer blade length.

[0039] <Third embodiment> [A] Details of turbine blades Fig. 5 is an enlarged view of a part of a turbine rotor blade 50 according to the third embodiment. Fig. 5 shows a cross-sectional view of a part similar to Fig. 3B.

[0040] As shown in Fig. 5, the turbine rotor blade 50 of this embodiment differs from the first embodiment (see Fig. 3B) in the configuration of the boundary BL between the first tip-side leading edge member 521 and the second tip-side leading edge member 522. Except for this point and related points, this embodiment is similar to the first embodiment. Therefore, explanations of overlapping points will be omitted where appropriate.

[0041] In the turbine rotor blade 50 of the embodiment, the boundary BL between the first tip side leading edge member 521 and the second tip side leading edge member 522 is formed to be inclined with respect to the axial direction AD of the turbine rotor 30. Here, the boundary BL is inclined with respect to the axial direction AD so that the leading edge LE side is located closer to the blade tip side OT in the radial direction RA than the trailing edge TE side (the right side in FIG. 5 ).

[0042] The angle AG at which the boundary BL between the first tip-side leading edge member 521 and the second tip-side leading edge member 522 is inclined with respect to the axial direction AD is, for example, not less than 15° and not more than 60°.

[0043] [B] Summary As described above, in this embodiment, since the boundary BL is inclined with respect to the axial direction AD as described above, stress caused by centrifugal force acting on the turbine rotor blade 50 due to operation of the steam turbine 1 is alleviated. Specifically, the load applied to the end of the boundary BL located on the side of the welded portion 540 is reduced. Therefore, in this embodiment, the same effects as in the first embodiment can be obtained, and the above configuration of the tip-side leading edge portion 520 can also be applied to turbine rotor blades 50 with longer blade lengths.

[0044] In addition, the turbine rotor blade 50 of this embodiment may also be provided with stress holes HL (see FIG. 4B) as in the second embodiment.

[0045] <Fourth embodiment> [A] Details of turbine blades Fig. 6 is an enlarged view of a part of the turbine rotor blade 50 according to the fourth embodiment. Fig. 6 shows a cross-sectional view of a part similar to Fig. 3B.

[0046] As shown in Fig. 6, the turbine rotor blade 50 of this embodiment differs from the first embodiment (see Fig. 3B) in the configuration of the boundary BL between the first tip-side leading edge member 521 and the second tip-side leading edge member 522. Except for this point and related points, this embodiment is similar to the first embodiment. Therefore, explanations of overlapping points will be omitted where appropriate.

[0047] In the turbine rotor blade 50 of the embodiment, the boundary BL between the first tip side leading edge member 521 and the second tip side leading edge member 522 includes a first boundary portion BL1, a second boundary portion BL2, and a third boundary portion BL3.

[0048] The first boundary portion BL1 is along the axial direction AD.

[0049] The second boundary portion BL2 is formed along the axial direction AD, closer to the trailing edge TE than the position where the first boundary portion BL1 is formed in the axial direction AD. The second boundary portion BL2 is located closer to the blade tip OT than the first boundary portion BL1 in the radial direction RA.

[0050] The third boundary portion BL3 is aligned along the radial direction RA and is interposed between the first boundary portion BL1 and the second boundary portion BL2. One end of the third boundary portion BL3 is connected to the first boundary portion BL1 and the other end is connected to the second boundary portion BL2. The corner portion of the third boundary portion BL3 that connects to the first boundary portion BL1 and the corner portion that connects to the second boundary portion BL2 are, for example, curved.

[0051] The length DS1 of the first boundary portion BL1, the length DS2 of the second boundary portion BL2, and the length DS3 of the third boundary portion BL3 are, for example, the same (DS1=DS2=DS3).

[0052] [B] Summary As described above, in the turbine rotor blade 50 of this embodiment, the tip leading edge portion 520 is in a state in which the first tip leading edge member 521 and the second tip leading edge member 522 are fitted together at the boundary BL. In addition, the load applied to the end of the boundary BL that is located on the side of the weld 540 is reduced. Therefore, in this embodiment, the same effects as in the first embodiment are obtained, and stress caused by centrifugal force acting on the turbine rotor blade 50 due to operation of the steam turbine 1 is alleviated. For this reason, in this embodiment, the above configuration of the tip leading edge portion 520 can be applied to turbine rotor blades 50 with a longer blade length.

[0053] In addition, the turbine rotor blade 50 of this embodiment may also be provided with stress holes HL (see FIG. 4B) as in the second embodiment.

[0054] Fifth Embodiment [A] Details of turbine blades 7 is an enlarged view of a part of a turbine rotor blade 50 according to a fifth embodiment. In FIG. 7, a cross-sectional view of a part similar to that in FIG.

[0055] As shown in Fig. 7, the turbine rotor blade 50 of this embodiment differs from the third embodiment (see Fig. 5) in the configuration of the boundary BL between the first tip-side leading edge member 521 and the second tip-side leading edge member 522. Except for this point and related points, this embodiment is similar to the third embodiment. Therefore, explanations of overlapping points will be omitted where appropriate.

[0056] In the turbine rotor blade 50 of the embodiment, the boundary BL between the first tip side leading edge member 521 and the second tip side leading edge member 522 includes a first boundary portion BL1 and a second boundary portion BL2.

[0057] The first boundary portion BL1 is aligned along the axial direction AD and is located closer to the trailing edge TE than the second boundary portion BL2 in the axial direction AD.

[0058] The second boundary portion BL2 is formed so as to be inclined with respect to the axial direction AD. The second boundary portion BL2 is inclined with respect to the axial direction AD so that the leading edge LE side is located closer to the blade tip OT in the radial direction RA than the trailing edge TE side. One end of the second boundary portion BL2 is connected to the first boundary portion BL1.

[0059] The length DS1 of the first boundary portion BL1 is, for example, the same as the length DS2 of the second boundary portion BL2 in the axial direction AD between one end and the other end (DS1=DS2).

[0060] [B] Summary As described above, in this embodiment, the boundary BL of the tip-side leading edge portion 520, the first boundary portion BL1 located closer to the trailing edge TE than the second boundary portion BL2 in the axial direction AD, is aligned along the axial direction AD, unlike the third embodiment (see FIG. 5). Therefore, in this embodiment, the same effects as the third embodiment can be obtained, and the second tip-side leading edge member 522 can be easily positioned and installed on the first tip-side leading edge member 521 before welding, thereby improving the efficiency of welding work.

[0061] In addition, the turbine rotor blade 50 of this embodiment may also be provided with stress holes HL (see FIG. 4B) as in the second embodiment.

[0062] <Other> Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Explanation of symbols]

[0063] 1: steam turbine, 10: outer casing, 12: cone portion, 20: inner casing, 30: turbine rotor, 31: rotor disk, 40: turbine stator blade, 41: diaphragm inner ring, 43: diaphragm outer ring, 45: nozzle diaphragm, 50: turbine rotor blade, 51: blade effective portion, 52: blade implant portion, 60: turbine stage, 70: steam supply pipe, 301: bearing, 510: blade main body portion, 520: tip side leading edge portion, 521: first tip side leading edge member, 522: second tip side leading edge member, 540: welded portion, AX: shaft center line, HL: stress hole, BL: boundary, BL1: first boundary portion, BL2: second boundary portion, BL3: third boundary portion, LE: leading edge, OT: blade tip side, RA: radial direction, RT: rotational direction, T30: blade implant groove, TE: trailing edge

Claims

1. A turbine rotor blade is provided in a turbine rotor of an axial flow steam turbine, and impinges upon water droplets contained in steam, which is a working fluid of the steam turbine, and a wing main body; a leading edge portion on the tip side formed of a material harder than that of the blade main body portion; the tip-side leading edge portion is disposed on the blade main body portion so as to be located on the blade tip side and on the leading edge side in the radial direction of the turbine rotor, The tip side front edge portion is a first tip-side leading edge member; a second tip side leading edge member disposed so as to be aligned with the first tip side leading edge member in the radial direction; Including, The first tip-side leading edge member and the wing main body, and the second tip-side leading edge member and the wing main body are joined by welds, whereas the first tip-side leading edge member and the second tip-side leading edge member are in an unjoined state. Turbine blades.

2. a boundary between the first tip side leading edge member and the second tip side leading edge member extending along an axial direction of the turbine rotor; The turbine blade of claim 1 .

3. The boundary between the first distal leading edge member and the second distal leading edge member is a boundary inclined portion formed so as to be inclined with respect to the axial direction of the turbine rotor; Including, a leading edge side of the boundary inclined portion is located closer to the blade tip side in the radial direction than a trailing edge side of the boundary inclined portion; The turbine blade of claim 1 .

4. The boundary between the first distal leading edge member and the second distal leading edge member is a first boundary portion formed along the axial direction of the turbine rotor; a second boundary portion formed along the axial direction on a trailing edge side of a position where the first boundary portion is formed in the axial direction; a third boundary portion interposed between the first boundary portion and the second boundary portion; Including, the second boundary portion is located closer to the blade tip than the first boundary portion in the radial direction. The turbine blade of claim 1 .

5. The boundary between the first distal leading edge member and the second distal leading edge member is a first boundary portion formed along the axial direction of the turbine rotor; a second boundary portion formed so as to be inclined with respect to the axial direction; At least the first boundary portion is located closer to a trailing edge than the second boundary portion in the axial direction, the second boundary portion is inclined with respect to the axial direction so that a leading edge side is located closer to the blade tip in the radial direction than a trailing edge side. The turbine blade of claim 1 .

6. Stress hole penetrating between the ventral and dorsal sides Including, the stress holes are formed so as to penetrate the boundary between the first tip side leading edge member and the second tip side leading edge member and the welded portion without penetrating the blade main body. The turbine rotor blade according to any one of claims 1 to 5.

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