Improvements relating to water turbine manufacturing

Abstract

The present invention relates to improvements in water turbine manufacture, in particular to a runner (4) for a hydraulic machine comprising a belt (20), a crown (22), a plurality of blades (24) extending between the crown (22) and the belt (20), where the runner (4) comprises a plurality of runner segments (30) together defining the runner (4), each runner segment (30) comprising a belt portion (34), a crown portion (32) and a blade (24), these portions being integrally formed with one another, each runner segment (30) is attachable to another segment at a belt engaging edge (40, 42) and a crown engaging edge (36, 38), where the belt engaging edge and the crown engaging edge are each spaced from the blades of the segment.

Description

[0001] This application is a divisional application of the PCT patent application "Improvements in turbine manufacturing" (application number: 201980010076.3, applicant: General Electric Renewable Energy Technology Company) which entered the Chinese national phase on July 24, 2020. Technical Field

[0002] The present invention relates to a runner for a turbine or other machine, and in particular, but not exclusively, to a runner for a hydraulic machine such as a turbine, pump or pump-turbine used, for example, in a hydroelectric power station. The invention also relates to a method of assembling such a runner, and to a hydraulic machine incorporating such a runner.

[0003] The invention relates in particular to a Francis type runner for a hydraulic machine, the runner being intended to pass a forced flow of water therethrough. In a turbine such as a Francis turbine, such flow has the effect of causing the runner to rotate. When the machine is a pump, such flow is caused by such rotation. Background Art

[0004] As is known in the art, hydraulic machines of the type described above comprise Francis-type runners, each comprising a band, a crown and blades extending between the band and the crown.

[0005] Such a runner can be made of a single piece, which can be formed as a casting, or can be welded. However, a hydraulic machine of the type described herein can have large dimensions (especially if the machine is used in a hydroelectric power station). As such, the runner can be expensive and take a long time to manufacture. In addition, the elements of a large runner (such as a crown and a band) are difficult to transport. In addition, the manufacture and construction of such a runner requires skills that are becoming increasingly difficult to find in the existing workforce. In addition, the manufacture of such a runner can bring health and safety issues due to the need to enter the restricted sections of the hydraulic channels of the runner in order to perform operations such as welding and grinding.

[0006] In known hydraulic presses of this type, it is known to divide the turbine runner into two or more segments in order to allow the runner to be transported from the manufacturing site to the location where the runner will be used. In such known hydraulic presses, the runner segments are assembled by forming welded joints at the crown, band and split blades. Summary of the invention

[0007] According to a first aspect of the invention, there is provided a runner for a hydraulic press, the runner comprising one or more of: a belt; a crown; a plurality of blades, preferably extending between the crown and the belt, wherein the runner preferably comprises a plurality of runner segments, which together may define the runner, each runner segment preferably comprising a belt portion, a crown portion and blades. Preferably, these portions and blades may be integrally formed with each other. Each runner segment may be capable of being attached to another segment at a belt engaging edge and a crown engaging edge, wherein the belt engaging edge and the crown engaging edge may each be spaced apart from the blades of the segment.

[0008] The hydraulic machine may comprise any machine, such as a turbine, a pump or a pump-turbine. In an embodiment of the invention, the hydraulic machine comprises a Francis turbine or a Francis pump. The hydraulic machine may be suitable for use in a hydroelectric power station.

[0009] According to another aspect of the invention there is provided a Francis type turbine comprising a runner as described herein.

[0010] Since the runner according to the invention is formed from a plurality of runner segments, some of the disadvantages highlighted above are overcome.

[0011] In addition, each runner segment may comprise a belt portion, a crown portion and blades. Preferably, each segment may comprise a single blade. The portions of the runner segment may be integrally formed. The runner segment may be formed by any convenient means and may, for example, be cast.

[0012] In each segment, the band may have at least one band engaging edge and the crown portion may have at least one crown engaging edge. Each of the engaging edges may be spaced apart from the blade of that segment. In other words, the blade may extend from a portion of the band portion that may be spaced apart from the band engaging edge and may extend to a portion of the crown portion that may be spaced apart from the crown engaging edge.

[0013] In each segment, the band may have a first band engaging edge and a second band engaging edge. The crown portion may have a first crown engaging edge and a second crown engaging edge. The blade may extend from a portion of the band portion positioned between the first band engaging edge and the second band engaging edge. The blade may extend from a portion of the band portion equidistant between the first band engaging edge and the second band engaging edge. The blade may extend to a portion of the crown portion between the first crown engaging edge and the second crown engaging edge. The blade may extend from a portion of the band portion equidistant between the first crown engaging edge and the second crown engaging edge.

[0014] The band and crown engaging edges are positioned so that the corresponding welds are at points where stress is minimal in use. In use, the areas of greatest stress on the runner are where the blades meet the band and crown.

[0015] Preferably, the band engaging edge and / or the crown engaging edge may be defined by the intersection of the cylinder with the band and / or crown.

[0016] This means that when two segments are joined together when forming a runner, it will not be necessary to form any joints near the blades. This overcomes the problem in existing prior art runners formed from runner segments where joints are formed at areas of greatest stress, such as at the junction between the blades and the crown or belt portion.

[0017] Thus, by means of the present invention, it is not necessary to weld the blades to the crown portion or the belt portion when forming the runner, nor is it necessary to form joints near the blades, since the blades are located away from the joint edges of the runner segments.

[0018] In an embodiment of the invention, each runner segment has substantially the same size and shape as each other runner segment.

[0019] This means that all segments can be formed from, for example, the same casting mould.

[0020] When the joint is formed by the weld, since the welding robot is able to access the joint, all welding is likely to be performed from the outside of the rotor, thereby avoiding accessibility issues, health and safety issues for the welding personnel.

[0021] In embodiments of the invention, each crown portion may have a first crown engaging edge and a second crown engaging edge, and each band may have a first band engaging edge and a second band engaging edge.

[0022] The first crown engaging edge and the second crown engaging edge may be spaced apart from each other to define opposite edges of the crown portion. Similarly, the first band engaging edge and the second band engaging edge of the band portion may be spaced apart from each other to define edges of the band portion.

[0023] In an embodiment of the present invention, the blade may extend from an area of ​​the crown portion that may be spaced apart from and between the first crown joining edge and the second crown joining edge, and the blade may extend to an area of ​​the band portion that may be spaced apart from and between the first band joining edge and the second band joining edge.

[0024] This position of the blades ensures that the blades are located away from the joint edges of the runner segments. This in turn ensures that it is not necessary to form welds and other joints anywhere near the most stressed areas of the runner segments, such as between the blades and the crown or belt portions.

[0025] In an embodiment of the present invention, the band joint edge and / or the crown joint edge may be curved. As will be described in more detail below, the curved shape of the joint edge enables a more efficient execution of the joint process.

[0026] The joining edge may have any particular curve. In a preferred embodiment of the invention, the joining edge preferably defines an arc of a circle or an arc of an ellipse. In other embodiments of the invention, the joining edge may define, for example, an elliptical curve.

[0027] According to a second aspect of the invention, there is provided a method of assembling a runner. The method may comprise one or more of the following steps: forming a runner segment, preferably comprising a belt portion, a crown portion and blades as an integral component, such that the belt portion may comprise a first belt engagement edge and a second engagement edge, the crown portion may comprise a first engagement edge and a second engagement edge, the edges may be spaced apart from the blades; and joining a plurality of runner segments together at the engagement edges to form the runner.

[0028] In an embodiment of the invention, the runner segments may be joined together by welding.

[0029] In some embodiments of the invention, the weld may be a narrow gap weld, however other welding processes may also be used.

[0030] Narrow gap welding can be performed on the outer surface of each segment, thus making the process more efficient and safer.

[0031] By using narrow gap welding technology, the quality of the weld can be improved. In addition, the weld volume can be reduced. In addition, when using automatic narrow gap welding technology, all weld parameters can be recorded.

[0032] In some embodiments of the present invention, welding is automatically performed using an automatic welding tool such as a robot welding tool. In such embodiments, the welding tool can follow a curved trajectory during the welding process.

[0033] In an embodiment of the invention, the trajectory may define a cylindrical surface.Alternatively or in combination, the trajectory may be defined by the intersection of a cylindrical surface, which may be circular or elliptical, with the band and crown.

[0034] By having a trajectory that follows a predetermined path, the welding process is simplified and automated welding is possible.

[0035] In embodiments of the invention, the curve of the trajectory followed by the welding tool may have any convenient radius, and in some embodiments of the invention, the radius of the surface of the cylinder defining the trajectory followed by the welding tool may be infinite. In such a case, the trajectory will be a straight line.

[0036] By means of the present invention, a runner for a hydraulic press is formed of a plurality of runner segments that are substantially identical to each other. Each runner segment will have a first crown engaging edge and a second crown engaging edge and a first belt engaging edge and a second belt engaging edge.

[0037] All of the joining edges are shaped as arcs defining a circle or other curved shapes. Thus, it is possible to utilize narrow gap welding using a robotic welding tool that can be programmed to follow a trajectory along the curve of the joining edges. In this way, welds can be formed along adjacent joining edges in order to join adjacent runner segments to form a runner.

[0038] According to a third aspect of the present invention, there is provided a hydraulic machine comprising a runner according to the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal cross-section of a turbine having a Francis wheel, the turbine comprising a rotatable turbine shaft coupled to the wheel; Figure 2 is a schematic perspective view of a Francis wheel according to an embodiment of the present invention; Figure 3 yes Figure 2 Side view of the Francis wheel; Figure 4 yes Figure 2 A schematic cross-sectional representation of a Francis wheel of FIG. 1 , showing how the individual wheel segments are welded together; Figure 5 is formed Figure 2 Schematic representation of a runner segment of a portion of a Francis runner; Figure 6a is a schematic representation of a joint between two segments of a pump runner of a pumped storage plant (PSP), illustrating a curved trajectory followed by a welding tool to join the segments together; Figure 6b is a schematic representation of a runner of a pumped storage plant (PSP) produced according to the invention; Figure 7 is a detailed representation of portions of adjacent runner segments showing gaps between adjacent segments formed when the segments abut one another; Figure 8 yes Figure 2 A partial perspective view of a Francis wheel of FIG. 1 showing a robotic welding tool joining adjacent wheel segments; and Fig. 9After being welded together and including the coupling flange welded to the top of the runner Figure 2 Cross-section representation of the Francis wheel. DETAILED DESCRIPTION

[0040] First reference Figure 1 , a hydraulic machine according to an embodiment of an aspect of the present invention is generally indicated by reference numeral 2. In the illustrated embodiment, the hydraulic machine 2 comprises a Francis turbine 4. The Francis turbine 4 in turn comprises a Francis runner 6 according to an embodiment of the present invention. During operation of the Francis turbine 4, water will enter the turbine via a conduit 8 and will flow through the Francis runner 6 (as indicated by arrow 10, in a known manner). The water will then exit via a conduit 12. As is well known in the art, the flow of water through the Francis runner 6 will cause the Francis runner to rotate, which in turn will cause the shaft 14 to rotate.

[0041] In other embodiments of the invention, the hydraulic machine may be, for example, a pump or a pump-turbine. When the hydraulic machine 2 comprises a pump, the rotation of the pump impeller will cause the flow of water in a known manner.

[0042] Now refer to Figures 2 to 9 The embodiments of the present invention are described in more detail.

[0043] like Figure 2 and Figure 3 As shown in FIG. 1 , the Francis wheel 6 includes a belt 20, a crown 22, and a plurality of blades 24. Each of the plurality of blades 24 extends from the crown 22 to the belt 20.

[0044] The Francis wheel 6 according to an embodiment of the present invention includes as shown in Figure 5 A plurality of runner segments 30 are shown in more detail in FIG.

[0045] Each runner segment 30 includes a crown portion 32 and a band portion 34. Each runner segment 30 includes a blade 24 extending between the crown portion 32 and the band portion 34.

[0046] The crown portion includes a first crown engaging edge 36 and a second crown engaging edge 38. Similarly, the band includes a first band engaging edge 40 and a second band engaging edge 42.

[0047] The blade 24 extends between the crown portion 32 and the band portion 34 from an area of ​​the crown portion spaced from both the first crown engaging edge 36 and the second crown engaging edge 38 to an area of ​​the band portion spaced from both the first band engaging edge 40 and the second band engaging edge 42 .

[0048] Such a configuration ensures that when the runner segments 30 are joined together, such as by a welding process, the welds formed are well away from high stress areas, which are typically where the blades 24 meet the crown 22 and band 20, respectively.

[0049] In this embodiment of the present invention, each runner segment 30 will be formed integrally by, for example, a casting process. In addition, the shape of each runner segment 30 used to form a complete Francis runner 6 will be substantially the same as each other segment.

[0050] When the Francis wheel 6 needs to be assembled, Figure 8 As shown in , the individual wheel segments are brought together and welds are formed to join adjacent segments to each other to form a complete Francis wheel 6. This process will be described in more detail below.

[0051] Now go to Figure 4 , schematically showing the positioning of welds for joining adjacent segments 30. As can be seen, a plurality of welds 50 have been formed to join adjacent runner segments 30 together to form a complete Francis turbine 6. Figure 4 It can be seen that the weld is located away from the blade 24. This ensures that the weld is not formed in an area of ​​high stress. This in turn means that the joint between adjacent segments will be stronger than may be the case in a similar prior art Francis turbine.

[0052] The weld may be formed by any convenient process, however, in this embodiment of the invention the weld has been formed using an automated narrow gap welding process.

[0053] To ensure that the process is efficient, both the crown engaging edge and the band engaging edge have been designed so that they are curved. This can be particularly useful in Figure 6a It can be seen that Figure 6a The shape of the joint between two segments of the runner is shown. Portions of the pump turbine belt are shown in solid outline.

[0054] Because the joining edge is curved, the welding tool can be programmed to follow a curved trajectory in the automated narrow gap welding process to form the weld 50. The trajectory is shown extending from the intersection of the cylinder and the strip. This trajectory must be followed by the welding tool to join the segments together.

[0055] In this embodiment of the present invention, as Figure 6a The trajectory followed by the welding tool will substantially track the surface of the cylinder, as shown by the dashed line 60 in FIG. Such a trajectory enables an efficient automated welding process to be performed, as there are no complex movements that must be performed by the welding tool.

[0056] The radius of the cylinder (whose surface is traced by the trajectory of the welding tool) can be any convenient radius, and in some embodiments of the invention, the radius must be infinite.In such embodiments of the invention, the trajectory of the welding tool will be substantially a straight line.

[0057] Figure 6b An assembled pump turbine runner which has been produced using the method according to the invention is shown.

[0058] Now go to Figure 7 , shows a detailed partial view of two adjacent runner segments 30. As can be seen from Figure 7 As can be seen, each segment is shaped with an extension 70 that forms part of the joining edge. This means that when adjacent runner segments are positioned close to each other in preparation for joining, a small gap 72 is formed. During the welding process, the weld is positioned within this gap 72.

[0059] The narrow gap corner chamfer may be 1° or 5° on each side of the gap. The size of the space between the two faces of the chamfer of the gap depends on the size of the torch. GTAW narrow gap torches may be used with the present invention. Thus, the chamfer root may have a diameter of, for example, about 13 mm. GMAW narrow gap torches typically require chamfer roots with larger diameters, for example, about 18 mm. Thus, the small gap 72 may have a diameter between approximately 13 mm and 18 mm. Other embodiments of the present invention may utilize gaps of other sizes as necessary.

[0060] Now go to Figure 8 , a robotic tool 80 is shown forming a weld 50 between adjacent wheel segments 30 .

[0061] Now go to Fig. 9 , shows a completed Francis wheel 6, wherein adjacent wheel segments 30 have been welded together. In addition, a coupling joint or flange 90 has been welded to the crown 22 of the Francis wheel 6 so that the wheel 4 can be connected to the Figure 1 The shaft 14 is shown in FIG.

[0062] The aforementioned embodiments are not intended to be limiting with respect to the scope of the following appended claims. In addition, the features of one or more of the above-mentioned embodiments may be easily combined with one or more features of another embodiment. It is also clear to the skilled person that various substitutions, changes and modifications may be made to the present invention without departing from the scope of the present invention as defined by the claims.

Claims

1. A runner for a hydraulic press, comprising: bring; crown; a plurality of blades extending between said crown and said band, wherein the runner comprises a plurality of runner segments together defining the runner, each runner segment comprising a band portion, a crown portion and blades, wherein the band portion, the crown portion and the blades are integrally formed with one another, each runner segment being attachable to another segment at a band engaging edge and a crown engaging edge, wherein the band engaging edge and the crown engaging edge are each spaced apart from the blades of the segment, wherein each of said runner segments includes an integral extension at said band engaging edge and said crown engaging edge; wherein the extensions meet and define a closed end of a gap between the band engaging edges or the crown engaging edges of adjacent runner segments, wherein the gap includes an open end facing outward from the runner surface and a chamfered side angled toward the closed end of the gap, wherein the gap includes a width to accommodate a narrow gap welding torch for subsequently welding adjacent runner segments together using a weld joint within the gap, wherein both the band engaging edge and the crown engaging edge are continuously curved along their entire lengths, wherein the continuous curve corresponds to the intersection of a constant radius cylinder with the band or the crown.

2. The rotating wheel according to claim 1, characterized in that: Each crown portion has a first crown engaging edge and a second crown engaging edge, and each band portion has a first band engaging edge and a second band engaging edge.

3. The rotating wheel according to claim 2, characterized in that: In each segment, the blade extends between the band portion and the crown portion from a portion of the band segment distal from both the first and second band engaging edges to a portion of the crown portion distal from the first and second crown engaging edges.

4. A running wheel according to any one of the preceding claims, characterised in that The band engaging edge and / or the crown engaging edge are curved.

5. The rotating wheel according to claim 4, characterized in that: The band engaging edge and / or the crown engaging edge defines an arc of a circle.

6. The running wheel according to claim 4 or claim 5, characterized in that: The band engaging edge and / or the crown engaging edge is defined by the intersection of a cylinder with the band and / or the crown.

7. A Francis type turbine comprising a runner according to any one of the preceding claims.

8. A method for assembling a rotating wheel, comprising the following steps: forming a runner segment comprising a band portion, a crown portion and blades as an integral component, such that the band portion comprises a curved first band engaging edge and a curved second engaging edge, the crown portion comprises a curved first engaging edge and a curved second engaging edge, the edges being spaced apart from the blades of the segment; a curved engagement edge formed with an integral extension, wherein the extensions meet and define a closed end of a gap between the band engagement edge and the crown engagement edge of adjacent runner segments, the gap having an open end facing outward from the runner and a chamfered side angled toward the closed end of the gap; wherein said curved joining edge is continuously curved along its entire length; Joining a plurality of runner segments together at the joining edge to form the runner, the joining process comprising: forming a weld in the gap between adjacent wheel segments using a robotic welding tool operated from the outside of the wheel with a narrow gap welding torch, Therein, for the respective corresponding curved joining edges of the crown portion and the band portion, the robotic welding tool follows a predetermined trajectory during the welding step, which corresponds to a respective constant radius cylinder intersecting the crown portion or the band portion.

9. The method according to claim 8, characterized in that The step of joining the plurality of runner segments together may include welding.

10. The method according to claim 8 or claim 9, characterized in that: The step of joining the plurality of runner segments together comprises narrow gap welding.

11. The method according to claim 9 or claim 10, characterized in that: The step of welding is performed by an automated welding tool which follows a predetermined trajectory during the welding process.

12. The method according to claim 11, characterized in that The trajectory defines a cylindrical surface and / or the trajectory is defined by the intersection between a cylinder and the crown and / or the band.

13. The method according to any one of claims 8 to 12, characterized in that The rotor is a Francis type rotor.

14. A hydraulic machine comprising a runner according to any one of claims 1 to 7.

15. The hydraulic press according to claim 14, characterized in that The hydraulic machine includes a Francis turbine.

Images