JP7542365B2 - Rotor blade cascade and steam turbine - Google Patents

Description

Embodiments of the present invention relate to a rotor blade cascade and a steam turbine.

A steam turbine has a casing into which high-temperature steam flows, a rotatable axle disposed within the casing, a number of rotor blades supported on the axle side, and a number of stator blades supported on the casing side.

A number of moving blades are arranged in a ring to form a moving blade cascade, and a number of stator vanes are arranged in a ring to form a stator vane cascade. These moving blade cascades and stator vane cascades are arranged alternately in the axial direction of the axle. In such a steam turbine, high-temperature steam that flows into the casing is straightened by each stator vane in the stator vane cascade, and then collides with each moving blade in the moving blade cascade. The energy generated by this collision causes the axle to rotate.

A typical rotor blade in recent years has a blade implantation section that fits into an implantation groove provided in a rotor disk that protrudes radially outward from the axle, an effective blade section that rises from the blade implantation section, and a snubber bar provided at the tip of the effective blade section. In a rotor blade cascade consisting of such rotor blades, the snubber bar of each rotor blade usually forms a ring that extends continuously in the entire circumferential direction. This type of structure is generally called a full-circumference single-group structure. This full-circumference single-group structure can effectively suppress vibrations that occur during operation and can effectively suppress leakage of high-temperature steam from between the rotor blades to the radially outward direction, thereby improving rotational efficiency.

Blade cascades are broadly divided into axial entry types, in which the blades are fitted into the installation grooves along the axial direction, and tangential entry types, in which the blades are fitted into the installation grooves along the circumferential direction.

In a tangential entry type rotor blade cascade, for example, rotor blades are fitted sequentially into a groove that extends around the entire circumference of the axle, and finally a rotor blade called a stop blade is fitted into the groove to form a ring.

Among the multiple rotor blades, those adjacent to the stop vane in the circumferential direction are generally called the stop vane adjacent to the rotor blade. In the above-mentioned tangential entry type rotor blade cascade, when fitting the stop vane between the stop vane adjacent to the stop vane, the stop vane may interfere with the stop vane adjacent to the stop vane, making it difficult to fit the stop vane in properly. In such cases, the snub vane of the stop vane adjacent to the stop vane or part of the snub vane of the stop vane may be cut out to allow the stop vane to pass between the stop vane adjacent to the stop vane.

However, cutting out part of the snubber tab as described above not only allows high-temperature steam to leak from the cutout, reducing performance, but also increases the time required to install the rotor blades, potentially delaying construction. In consideration of these issues, structures have been proposed in the past, such as splitting the blade installation section of the stop vane or providing a slope on the stop vane snubber tab to gradually reduce its width.

Patent No. 4284204 Patent No. 5380323

Various technologies have been proposed to make it easier to install the stop vanes, but existing technologies have problems such as the need for many parts and excessive manufacturing load.

The problem that the present invention aims to solve is to provide a rotor blade cascade and a steam turbine equipped with the same that can simplify the assembly of rotor blades while suppressing an increase in the number of parts and manufacturing load.

The rotor blade cascade according to one embodiment includes a blade implantation portion that is fitted into an implantation groove that extends in the circumferential direction of the axle, a blade effective portion that rises from the blade implantation portion, and a snubber blade provided at the tip of the blade effective portion, and includes a plurality of rotor blades arranged in a ring shape. The rotor blades include a stopper blade, a first stopper adjacent blade and a second stopper adjacent blade that are arranged on both sides of the stopper blade in the circumferential direction, and a plurality of general blades that are arranged on the side opposite the stopper blade side of each of the first stopper adjacent blade and the second stopper adjacent blade. When the stop wing is disposed between the first stop adjacent wing and the second stop adjacent wing, the end surface of the snubber tab of the stop wing on the first stop adjacent wing side exceeds the first surface, which includes the contact surface between the blade implantation portion of the stop wing and the blade implantation portion of the first stop adjacent wing, on the first stop adjacent wing side as a whole or in part and is flush with the first surface on the other part, and/or the end surface of the snubber tab of the stop wing on the second stop adjacent wing side exceeds the second surface, which includes the contact surface between the blade implantation portion of the stop wing and the blade implantation portion of the second stop adjacent wing, on the second stop adjacent wing side as a whole or in part and is flush with the second surface on the other part.

The steam turbine in one embodiment is a steam turbine in which the rotor blade cascade is supported on an axle.

The present invention makes it possible to simplify the assembly work of rotor blades while reducing the number of parts and manufacturing load.

FIG. 2 is a perspective view of a turbine rotor included in a steam turbine according to one embodiment, illustrating a state in which a stopper vane of a rotor vane is assembled to an axle side constituting the turbine rotor. 2 is a view showing a part of a blade cascade assembled in the turbine rotor shown in FIG. 1 as viewed in the axial direction. FIG. 3 is a view of a portion of the rotor blade cascade shown in FIG. 2 as viewed from the radially outer side. FIG. 1 is a diagram showing a portion of a typical rotor blade cascade viewed in the axial direction. FIG. 5 is a view of a portion of the rotor blade cascade shown in FIG. 4 as viewed from the radially outer side. FIG. 5 is a diagram showing the size of a space formed between a pair of adjacent stop blades in the rotor blade cascade of the turbine rotor according to the embodiment shown in FIG. 2, and the size of a space formed between a pair of adjacent stop blades in the general rotor blade cascade shown in FIG.

One embodiment will be described in detail below with reference to the attached drawings.

Figure 1 is a perspective view of a turbine rotor 10 provided in a steam turbine 1 according to one embodiment, showing the turbine rotor 10 in a partially cut-away state. The turbine rotor 10 includes an axle 11 that can rotate in a casing (not shown), a rotor disk 12 that protrudes radially outward from the outer circumferential surface of the axle 11, and a blade cascade VS consisting of a plurality of blades 20 fitted into a mounting groove 12A formed in the rotor disk 12.

Each of the multiple moving blades 20 has a blade implantation portion A that is fitted into the implantation groove 12A, a blade effective portion B that rises radially outward from the blade implantation portion A, and a snubber backbone C provided at the tip of the blade effective portion B. The multiple moving blades 20 include a stopper blade 21, a first stopper adjacent blade 22 and a second stopper adjacent blade 23 that are arranged on both sides of the stopper blade 21 in the circumferential direction, and multiple general blades 24 that are arranged on the side opposite the stopper blade 21 side of the first stopper adjacent blade 22 and the second stopper adjacent blade 23. The stopper blade 21, the first stopper adjacent blade 22, the second stopper adjacent blade 23, and the general blade 24 each have a blade implantation portion A, a blade effective portion B, and a snubber backbone C.

The installation groove 12A formed in the rotor disk 12 extends in the circumferential direction and has a receiving opening 12B that widens in the axial direction in part of it. The installation groove 12A opens radially outward and has a narrowed portion that is narrower than the width of the bottom side, located closer to the opening than the bottom. The blade installation portion A of the rotor blade 20 is prevented from coming out by the narrowed portion, and in this state it is fitted into the installation groove 12A.

When assembling the multiple rotor blades 20 into the rotor disk 12, first, the blade installation portion A of the general blade 24 is passed through the receiving port 12B from the radial outside, and then the general blade 24 is moved circumferentially within the installation groove 12A, and all of the general blades 24 are fitted into the installation groove 12A. Next, the first stop adjacent blade 22 and the second stop adjacent blade 23 are fitted into the installation groove 12A in the same manner as the general blade 24 so that they are in contact with the general blades 24 located at both ends of the multiple general blades 24. Finally, the blade installation portion A of the stop blade 21 is passed through the receiving port 12B from the radial outside, and is positioned between the first stop adjacent blade 22 and the second stop adjacent blade 23.

Figure 1 shows the final installation of the retaining blade 21. When all the rotor blades 20 (21-24) are fitted into the installation grooves 12A, the rotor blades 20 (21-24) are arranged in a ring shape. In this state, the blade installation portions A of adjacent rotor blades 20 come into contact with each other, and the snubber blades C of adjacent rotor blades 20 come into contact with each other.

Figure 2 is a view of a portion of the rotor blade cascade VS assembled in the turbine rotor 10, viewed in the axial direction, showing a stop vane 21, a first stop adjacent vane 22, a second stop adjacent vane 23, and two general vanes 24. Figure 3 is a view of a portion of the rotor blade cascade VS shown in Figure 2, viewed from the radial outside.

In Figures 2 and 3, the symbol S1 indicates a first surface that includes the contact surface between the blade implantation portion A of the stop vane 21 and the blade implantation portion A of the first stop adjacent vane 22 and extends radially outward beyond the snub bar C. The symbol S2 indicates a second surface that includes the contact surface between the blade implantation portion A of the stop vane 21 and the blade implantation portion A of the second stop adjacent vane 23 and extends radially outward beyond the snub bar C.

Here, in this embodiment, the end face 211 on the first adjacent wing 22 side of the snub-back bar C of the retaining wing 21 either entirely exceeds the first surface S1 toward the first adjacent wing 22 side or exceeds a portion and is flush with the first surface S1 at another portion. Specifically, in this example, as shown in FIG. 3, the end face 211 exceeds the first surface S1 at a portion and is flush with the first surface S1 at another portion. On the other hand, the end face 212 on the second adjacent wing 23 side of the snub-back bar C of the retaining wing 21 exceeds the second surface S2 toward the second adjacent wing 23 at a portion, but does not exceed the second surface S2 at another portion.

In this embodiment, the first stop adjacent wing 22 is disposed on the ventral side of the effective blade portion B of the stop blade 21, and the second stop adjacent wing 23 is disposed on the suction side of the effective blade portion B of the stop blade 21. Therefore, the end face of the effective blade portion B of the snubber wing C of the stop blade 21 on the ventral side extends beyond the first surface S1 in part and is flush with the first surface S1 in other parts.

As described above, when the end face 211 of the snub-cutter blade C of the retaining blade 21 extends beyond the first surface S1 in part and is flush with the first surface S1 in other parts, a wide space is secured between the first retaining adjacent blade 22 and the second retaining adjacent blade 23. This makes it easier to pass the retaining blade 21 between the first retaining adjacent blade 22 and the second retaining adjacent blade 23, improving the ease of assembly.

Figure 4 is a view of a portion of a typical rotor blade cascade in the axial direction, showing the stop vane 21', the first stop adjacent vane 22', the second stop adjacent vane 23', and two general vanes that constitute the typical rotor blade cascade. Figure 5 is a view of a portion of the rotor blade cascade shown in Figure 4 as seen from the radial outside. In Figures 4 and 5, the surfaces corresponding to the first surface S1 and the second surface S2 shown in Figures 2 and 3 are indicated by the same reference numerals. As shown in Figures 4 and 5, in a typical rotor blade cascade, the end surface 211' of the snubber cover of the stop vane 21' on the first stop adjacent vane 22' side exceeds the first surface S1 in part, but does not exceed the first surface S1 in other parts. Also, the end surface 212' of the snubber cover of the stop vane 21' on the second stop adjacent vane 23' side also exceeds the second surface S2 in part, but does not exceed the second surface S2 in other parts.

Figure 6 is a view from the radial outside showing the size of the space formed between a pair of adjacent stop vanes 22, 23 in the turbine rotor 10 according to this embodiment, and the size of the space formed between a pair of adjacent stop vanes 22', 23' in the rotor blade cascade of a typical turbine rotor shown in Figure 4. In Figure 6, a typical rotor blade cascade is shown below the rotor blade cascade VS according to this embodiment.

In the example shown in FIG. 6, when the circumferential width of the minimum space formed between a pair of adjacent stop blades 22', 23' in the general rotor blade cascade shown in FIG. 4 is A, and the circumferential width of the space on the blade leading end side from the circumferential width A is B, between the pair of adjacent stop blades 22, 23 in the turbine rotor 10 according to this embodiment, the circumferential width of the space corresponding to the above minimum space is A + α, and the circumferential width of the space corresponding to the above space on the blade leading end side is B + β. In this way, in this embodiment, the space between the pair of adjacent stop blades 22, 23 can be secured to be wider than in a general structure. The above α and β may be equal to each other or may be different values.

That is, the symbol X in FIG. 6 indicates the approximate circumferential width of the blade implantation portion A of the stop vane 21 in this embodiment, and the symbol X' indicates the approximate circumferential width of the blade implantation portion of the stop vane 21' in a general rotor blade cascade. In this embodiment, the difference between the circumferential width X of the blade implantation portion A of the stop vane 21 and the circumferential width A+α or B+β of the space between a pair of adjacent stop vanes 22, 23 can be made smaller than the difference between the circumferential width X' and the circumferential width A or B in the case of a general rotor blade cascade. In a general rotor blade cascade, for example, the difference between the circumferential width X' and the circumferential width A is large, and the width of the blade implantation portion of the stop vane 21' is much larger than the space of the circumferential width A. Therefore, the work of passing the blade implantation portion of the stop vane 21' between the adjacent stop vanes may be time-consuming. In particular, the blade implantation portion of the stop vane 21' is likely to interfere with the portion surrounded by the symbol PR in FIG. 6.
That is, in this embodiment, the protrusion amount of the snub-back tab C of the stop vane 21 toward the adjacent stop vane 22, the retraction amount of the snub-back tab C of the adjacent stop vane 22 from the stop vane 21, and the circumferential thickness between the blade planting portion A of the stop vane 21 and the blade planting portion A of the first adjacent stop vane 22 (i.e., the position of the first surface S1) are adjusted so that the end face 211 of the snub-back tab C of the stop vane 21 on the first adjacent stop vane 22 side exceeds the first surface S1 entirely toward the first adjacent stop vane 22 side or exceeds it partially and becomes flush with the first surface S1 at the other part. This makes it easier to pass the stop vane 21 between the first adjacent stop vane 22 and the second adjacent stop vane 23.

The operation of the present embodiment described above is as follows:

That is, when the stop vane 21 is disposed between the first stop vane 22 and the second stop vane 23, the vane implantation portion A of the stop vane 21 is less likely to interfere with the snub vane C of the first stop vane 22 and the snub vane C of the second stop vane 23, making it easier to assemble the stop vane 21. This simplification of assembly is achieved by adjusting the dimensions of the vane implantation portion A and the snub vane C of the stop vane 21 and the stop vane adjacent vanes 22 and 23, respectively, so that the number of parts of the rotor vane is not increased and excessive effort is not required for manufacturing the rotor vane.

Therefore, the rotor blade cascade VS according to this embodiment has the effect of simplifying the rotor blade assembly work while suppressing an increase in the number of parts and manufacturing load. In addition, since it is possible to avoid a situation in which it is necessary to cut out the snubber blade C of the first stop adjacent blade 22 when assembling the rotor blade, it is possible to avoid a decrease in performance due to the machining of the notch.

Although one embodiment has been described above, the above embodiment is presented as an example and is not intended to limit the scope of the invention. This new embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiment and other modifications are included within the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

For example, in the above embodiment, the end face 211 of the snub-stopper C of the stopper wing 21 on the side of the first stopper adjacent wing 22 extends beyond the first surface S1 in part and is flush with the first surface S1 in another part, but instead of or at the same time, the end face 212 of the stopper wing 21 on the side of the second stopper adjacent wing 23 may extend beyond the second surface S2 entirely toward the second stopper adjacent wing 23 side or may extend beyond the second surface S2 in part and be flush with the second surface S2 in another part.

In addition, in the above embodiment, the blade installation portions of the first stop adjacent blade 22, the second stop adjacent blade 23, and the general blade 24 are T-shaped, but this shape is not particularly limited and may be saddle-shaped, etc.

1...steam turbine, 10...turbine rotor, 11...axle, 12...rotor disk, 12A...implantation groove, 12B...receiving port, VS...row of moving blades, 20...moving blade, A...blade implantation portion, B...blade effective portion, C...snubber blade, 21...stop blade, 211...end surface, 22...first stop adjacent blade, 23...second stop adjacent blade, 24...general blade

Claims (3)

The rotor blade has a blade installation portion that is fitted into an installation groove that extends in a circumferential direction of the axle, a blade effective portion that rises from the blade installation portion, and a snubber cover provided at a tip of the blade effective portion, and the rotor blade is provided with a plurality of blades that are arranged in an annular shape;
The rotor blade includes a stop vane, a first stop vane adjacent to the stop vane and a second stop vane adjacent to the stop vane in the circumferential direction, and a plurality of general vanes arranged on the opposite side of the stop vane to the first stop vane adjacent to the stop vane and the second stop vane adjacent to the stop vane,
When the stop vane is disposed between the first stop vane and the second stop vane, an end face of the stop vane on the first stop vane side of the snub vane entirely extends beyond a first surface including a contact surface between the vane planting portion of the stop vane and the vane planting portion of the first stop vane and extending radially outward toward the first stop vane side, and/or an end face of the stop vane on the second stop vane side of the snub vane entirely extends beyond a second surface including a contact surface between the vane planting portion of the stop vane and the vane planting portion of the second stop vane and extending radially outward toward the second stop vane side ,
The blade implantation portion of the stop vane can be positioned between the first stop adjacent vane and the second stop adjacent vane from the radially outer side . 2. The rotor blade cascade according to claim 1, wherein the first stop adjacent vane is disposed on a ventral side of the vane effective portion of the stop vane, and the second stop adjacent vane is disposed on a suction side of the vane effective portion of the stop vane. A steam turbine comprising a rotor blade cascade according to claim 1 or 2 supported on an axle.

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