JP2020084799A - Fluid machine, seal member and method for modifying fluid machine - Google Patents

Abstract

To provide a fluid machine that has improved seal effect with respect to the fluid passing between a rotary member and a stationary member and can effectively suppress leakage losses.SOLUTION: A fluid machine includes: a runner 2 rotating with pressure of a water flow; and a seal liner 21 covering the runner 2. The seal liner 21 includes: a groove 22 extending in a circumferential direction; and a damming part 23 positioned so as to be partially buried in the groove 22.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a fluid machine, a seal member, and a method of repairing a fluid machine.

Some fluid machines used for hydroelectric power generation have a runner that is a rotating member, and an upper cover and a lower cover that are stationary members that cover the runner. In such a fluid machine, a space called a back pressure chamber is formed between the runner and the upper cover, and a space called a side pressure chamber is formed between the runner and the lower cover.

The runner rotates by receiving the pressure of the water flow at its runner blades, and generates power for hydroelectric power generation. However, during such an operation, there is a water flow that passes through the back pressure chamber and the side pressure chamber without passing through the runner.

Since the water flow that does not pass through the runner does not exert a fluid force on the runner blade, the efficiency of the fluid machine decreases as the flow rate of the water flow that passes through the back pressure chamber and the side pressure chamber increases. The water flow thus flowing through the back pressure chamber and the side pressure chamber is generally called a leakage flow, and the loss caused by the leakage flow is generally called a leakage loss.

There are various techniques for suppressing the leakage loss. For example, a minute gap is formed between the runner and the stationary member within a structurally allowable size range, and the minute gap allows the leakage flow to flow. There are known seal structures for suppressing and seal structures for forming a rectangular or thread-shaped protrusion on the seal surface on the stationary member side to narrow the gap.

A seal structure is also known in which a circumferential groove is formed in the wall portion of the rotating member or the wall portion of the stationary member facing each other. In this seal structure, the flow passage area of the gap is expanded and contracted by the groove, whereby the leak flow is decelerated and then immediately accelerated, and a sealing effect can be obtained by collision, friction with the wall surface, or the like.

Japanese Utility Model Publication No. 54-53145 Japanese Patent No. 5835687

By the way, the leakage flow flowing through the gap between the rotating member and the stationary member has a large circumferential velocity component when passing through the gap due to friction with the rotating member. Although the above-described seal structure in which the circumferential groove is formed in the wall portion of the rotating member or the wall portion of the stationary member can effectively reduce the axial velocity component of the leakage flow, it can reduce the circumferential velocity component. There is room for improvement regarding deceleration.

The present invention has been made in consideration of the above circumstances, and a fluid machine, a seal member, and a fluid machine capable of improving a sealing effect on a fluid passing between a rotating member and a stationary member and effectively suppressing a leakage loss. The purpose is to provide a repair method.

A fluid machine according to one embodiment includes a rotating member that rotates by the pressure of a fluid, and a stationary member that covers the rotating member. At least one of the wall portion of the rotating member and the wall portion of the stationary member facing each other has a groove extending in the circumferential direction, and a damming portion positioned so as to partially fill the groove. ..

A fluid machine according to one embodiment includes a rotating member that rotates by the pressure of a fluid, and a stationary member that covers the rotating member. Between the wall portion of the rotating member and the wall portion of the stationary member that face each other, a first gap and a second gap that is separated from the first gap in both the radial direction and the axial direction. A third gap that is located between the first gap and the second gap and that is connected to both the first gap and the second gap so as to form a bent shape is formed. There is. At least one of the wall portion of the rotating member and the wall portion of the stationary member has a damming portion positioned so as to partially fill the third gap.

A seal member according to an embodiment includes a rotating member that rotates by the pressure of a fluid, and a stationary member that covers the rotating member, and includes a wall portion of the rotating member and a wall portion of the stationary member that face each other. At least one of the two is a seal member used in a fluid machine having a groove extending in the circumferential direction. The seal member is arranged inside the groove and provided so as to partially fill the groove.

A method for repairing a fluid machine according to an embodiment includes a rotating member that rotates by the pressure of a fluid, and a stationary member that covers the rotating member, and a wall portion of the rotating member and a wall of the stationary member that face each other. At least one of the parts is a method of repairing a fluid machine having a groove extending in the circumferential direction. The repairing method includes a step of preparing a damming portion and a step of providing the damming portion inside the groove so as to partially fill the groove.

ADVANTAGE OF THE INVENTION According to this invention, the sealing effect with respect to the fluid which passes between a rotating member and a stationary member is improved, and a leakage loss can be suppressed effectively.

It is a meridian sectional view of the Francis type water turbine as a fluid machine which concerns on 1st Embodiment. It is an enlarged meridian sectional view of the seal structure formed between the runner and the lower cover of the Francis turbine according to the first embodiment. FIG. 3 is a schematic view of a lower cover side portion that constitutes the seal structure in the first embodiment, as viewed in a direction of an arrow III in FIG. 2. (A) is a figure explaining the fluid machine which concerns on 2nd Embodiment, Comprising: When the lower cover side part which comprises the sealing structure is seen in the same direction as the direction of the arrow III of FIG. FIG. 4B is a schematic diagram of FIG. 4B, and FIGS. It is a figure explaining the fluid machine which concerns on 3rd Embodiment, Comprising: It is the schematic when the lower cover side part which comprises the sealing structure is seen in the same direction as the direction of the arrow III of FIG. .. It is a figure explaining the fluid machine which concerns on 4th Embodiment, Comprising: It is the schematic when the part by the side of the lower cover which comprises the sealing structure is seen in the same direction as the direction of the arrow III of FIG. .. It is a figure explaining the fluid machine which concerns on 5th Embodiment, Comprising: It is the schematic when the part by the side of the lower cover which comprises the sealing structure is seen in the same direction as the direction of the arrow III of FIG. .. It is sectional drawing which follows the VIII-VIII line of FIG. It is a figure explaining the fluid machine concerning a 6th embodiment, and is a meridional cross section of the seal structure. It is sectional drawing which follows the XX line of FIG.

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a meridional sectional view of a part of a Francis turbine 1 as a fluid machine according to a first embodiment. It should be noted that although the Francis turbine 1 is described as an example of the fluid machine here, the fluid machine is not limited to the turbine. Further, in FIG. 1, for convenience of description, the hatching of the constituent members of the Francis turbine 1 is omitted.

In the Francis type turbine 1 shown in FIG. 1, when the turbine is in operation, the water flow from the casing 10 flows into the runner 2 that is a rotating member via the stay vanes 11 and the guide vanes 12, and the runner 2 rotates due to the pressure of the flowing water flow. It rotates about the axis C1.

In the following description, when simply saying the axial direction, the direction means a direction on the rotation axis C1 or a direction along the rotation axis C1. The term circumferential direction means a direction along which the runner 2 rotates about the rotation axis C1, and the term radial direction means a direction orthogonal to the rotation axis C1.

The runner 2 includes a plurality of runner blades 3 arranged side by side in the circumferential direction, a crown 4 that is an annular member that fixes the plurality of runner blades 3 from one side in the blade height direction, and a fixed from the other side. And a band 5 which is an annular member.

Reference numeral 6 in the drawing denotes a lower cover as a stationary member that covers the band 5 of the runner 2 from the outside in the radial direction. A side pressure chamber 7, which is a space, is formed between the band 5 and the lower cover 6. Although illustration is omitted, an upper cover as a stationary member that covers the crown 4 from above is provided above the crown 4, and a back pressure chamber that is a space is formed between the upper cover and the crown 4.

In the present embodiment, the seal structure 20 is formed in the downstream side portion of the side pressure chamber 7 in the direction of the water flow, and the seal structure 20 forms a minute gap that narrows the space between the band 5 and the lower cover 6. This makes it difficult for the leak flow to pass through.

FIG. 2 is an enlarged meridional sectional view of the seal structure 20. As shown in FIG. 2, the seal structure 20 according to the present embodiment includes a seal liner 21 that is attached to a downstream side portion of the lower cover 6 in the water flow direction and covers the band 5 from the outside in the radial direction, and a seal liner 21 in the water flow direction. It is composed of the downstream side portion of the band 5. In the seal structure 20, the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 that face each other in the radial direction form a minute gap by narrowing the gap more than the upstream side. The minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 extends in the circumferential direction in series so as to form an annular shape.

The wall portion 21A of the seal liner 21 has a groove 22 extending in the circumferential direction, and the groove 22 in the present embodiment is formed in an annular shape extending over the entire circumference in the circumferential direction in the horizontal plane. However, the groove 22 need not be annular and may be arcuate. Further, although three grooves 22 are formed in FIG. 2, the number of grooves 22 is not particularly limited. Further, the cross-sectional shape of the groove 22 in the present embodiment is rectangular in the meridional section, but the cross-sectional shape is not particularly limited, and may be trapezoidal or semi-circular, for example.

FIG. 3 is a schematic view of a portion of the seal structure 20 on the lower cover 6 side, specifically, the seal liner 21 when viewed in the direction of arrow III in FIG. As shown in FIGS. 2 and 3, the runner 2 according to the present embodiment is provided with a damming portion 23 positioned so as to partially fill the groove 22. In the present embodiment, one damming portion 23 is provided in each groove 22, but a plurality of damming portions 23 may be provided in one groove 22. Further, some of the plurality of grooves 22 may not be provided with the damming portion 23.

The damming portion 23 cooperates with the groove 22 to function as a sealing member for enhancing the sealing effect. The damming portion 23 illustrated in the present embodiment completely fills the space between the walls of the grooves 22 that face each other in the axial direction, but provides a gap between the walls of the grooves 22 that face each other in the axial direction. It may be provided. Further, the shape of the damming portion 23 is rectangular when viewed in the radial direction, but the shape is not particularly limited. Further, the method of forming the damming portion 23 is not particularly limited, and may be formed as an integrated body of the seal liner 21, or may be formed as a separate body of the seal liner 21 and welded to the seal liner 21. It may be attached.

Next, the operation of this embodiment will be described with reference to FIGS. 2 and 3.

When the water flow from the casing 10 flows into the runner 2, which is a rotating member, via the stay vanes 11 and the guide vanes 12 during the operation of the water turbine, the runner 2 is rotated by the pressure of the water flow at the runner blades 3. At this time, a leak flow, which is a part of the water flow, flows into the side pressure chamber 7.

The leakage flow in the side pressure chamber 7 is suppressed from passing to the downstream side by the minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 in the seal structure 20, and the flow passage area by the groove 22 is suppressed. By repeatedly decelerating and accelerating by increasing and decreasing, the passage to the downstream side is further suppressed. However, at this time, the leakage flow in the minute gap is affected by the rotation of the band 5 as shown by an arrow α in FIG. 3, and has a circumferential velocity in the same direction as the rotation direction R. Then, a situation may occur in which the circumferential velocity of the leak flow cannot be sufficiently suppressed only by the groove 22, and the leak flow tries to flow out from the seal structure 20 while maintaining the fast velocity.

At this time, in the present embodiment, the damming portion 23 located so as to partially fill the groove 22 is provided, so that the leak flow having the circumferential velocity as described above causes the groove 22 in the minute gap to flow. When passing, it collides with the blocking portion 23 and is blocked. As a result, the leak flow is rapidly and largely decelerated, so that passage of the leak flow is suppressed as compared with the case where only the groove 22 is provided.

As described above, according to the present embodiment, the sealing effect with respect to the water flow (leakage flow) passing between the runner 2 and the seal liner 21 can be improved, and the leakage loss can be effectively suppressed.

In addition, in the present embodiment, it is assumed that the damming portion 23 is provided when manufacturing a new fluid machine, but the damming portion 23 is already installed in, for example, an existing power plant having the groove 22. It may be provided for the purpose of repairing the fluid machine. In this case, the damming portion 23 may be prepared, and the damming portion 23 that partially fills the groove may be provided inside the existing circumferential groove.

<Second Embodiment>
Next, a second embodiment will be described. The same parts as those of the first embodiment among the parts of the present embodiment are designated by the same reference numerals, and description of common parts may be omitted.

In the present embodiment, as shown in FIG. 4A, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and a damming portion 23 is provided corresponding to each of the plurality of grooves 22. ..

In the plurality of damming portions 23, at least a part of the damming portion 23 located on the downstream side in the direction of the water flow indicated by the arrow F has a rotation direction of the runner 2 more than that of the damming portion 23 located on the upstream side. It is arranged so as to be located on the opposite side of R. Further, the damming portions 23 adjacent to each other in the axial direction overlap each other in the axial direction.

Also in the present embodiment, the leakage flow in the minute gap between the wall portion 21A of the seal liner 21 and the wall portion 5A of the band 5 has a circumferential component as shown by an arrow α, but it does not flow to the damming portion 23. The collision reduces the circumferential speed. After that, the decelerated leak flow flows out from the groove 22 and tends to flow in the axial direction.

Here, in the present embodiment, the dam portion 23 on the downstream side is located on the opposite side of the dam portion 23 on the upstream side in the rotation direction R. Thus, when the leak flow decelerated by the upstream dam 23 flows out from the groove 22 and tries to flow in the axial direction, the pressure becomes higher than that in the groove 22 on the downstream dam 23. Passage is restricted by the area where Thereby, the leakage flow is effectively suppressed, so that the leakage loss can be effectively reduced.

4B and 4C show a modification of the second embodiment. In the modification of FIG. 4(B), the length of the damming portion 23 in the circumferential direction is longer on the downstream side. As a result, at least a part of the damming portion 23 located on the downstream side in the water flow direction is located on the opposite side to the rotation direction R of the runner 2 than the damming portion 23 located on the upstream side.

Further, in FIG. 4C, at least a part of the damming portion 23 located on the downstream side in the direction of the water flow is located on the opposite side to the rotation direction R of the runner 2 than the damming portion 23 located on the upstream side. However, the damming portions 23 that are adjacent to each other in the axial direction are separated in the circumferential direction and do not overlap each other in the axial direction.

<Third Embodiment>
Next, a third embodiment will be described. The same parts as those of the first and second embodiments among the parts of the present embodiment are designated by the same reference numerals, and description of common parts may be omitted.

As shown in FIG. 5, in the present embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and a damming portion 23 is provided corresponding to each of the plurality of grooves 22.

Then, as the end surface 23A of the damming portion 23 facing the opposite side to the rotation direction R of the runner 2 extends from the upstream side toward the downstream side in the direction of the water flow indicated by the arrow F, the end surface 23A is inclined so as to extend to the opposite side to the rotation direction R. is doing.

In the present embodiment, after colliding with the damming portion 23 and the circumferential speed is reduced, the leak flow in the axial direction is further dammed by the inclined end surface 23A and is decelerated. Thereby, the leakage flow is effectively suppressed, so that the leakage loss can be effectively reduced.

<Fourth Embodiment>
Next, a fourth embodiment will be described. Of the components in this embodiment, those similar to the components in the first to third embodiments are designated by the same reference numerals, and description of common parts may be omitted.

As shown in FIG. 6, in the present embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and a damming portion 23 is provided corresponding to each of the plurality of grooves 22. The groove 22 is inclined at an angle β with respect to the horizontal direction so as to extend in the circumferential direction and extend in the axial direction.

The angle β is set to be larger than 0° and is preferably set to 10° to 45° in consideration of the influence of leak flow.

Also in the present embodiment, the same effect as that of the first embodiment can be obtained.

<Fifth Embodiment>
Next, a fifth embodiment will be described. Of the constituent parts of the present embodiment, the same parts as those of the first to fourth embodiments are designated by the same reference numerals, and description of common parts may be omitted.

As shown in FIG. 7, in the present embodiment, a plurality of grooves 22 are provided in the seal liner 21 at intervals in the axial direction, and a damming portion 23 is provided corresponding to each of the plurality of grooves 22.

As shown in FIG. 8, the damming portion 23 has a through hole 23B through which the bolt 24 is inserted, and is fixed inside the groove 22 by the bolt 24 which is a fastening member. As shown in FIG. 8, a bolt hole 25 is formed in the seal liner 21, and the bolt 24 is fastened to the bolt hole 25. In the illustrated example, the bolt 24 is fastened so as not to project (project) from the wall portion 21A of the seal liner 21, but the bolt 24 may project from the wall portion 21A. Further, in the illustrated example, the bolt 24 does not penetrate the seal liner 21, but the bolt 24 penetrates the seal liner 21 and is tightened with a nut on the tip portion of the bolt 24 exposed by penetrating radially outward from the seal liner 21. Therefore, the damming portion 23 may be fixed.

When forming the damming portion 23 in the groove 22, for example, the damming portion 23 can be formed by shaving at the same time when the groove 22 is shaved, but the damming portion 23 is processed exactly as designed. This leads to an increase in the groove processing step. This increases significantly as the number of locations where the damming portion 23 is provided increases. On the other hand, in the present embodiment, since the damming portion 23 is fixed by the bolt 24 after the groove 22 is processed, the groove processing step can be shortened.

Further, since the leak flow in the side pressure chamber 7 may contain earth and sand, the damming portion 23 is worn by the leak flow containing earth and sand, and the effect of damaging the flow cannot be obtained over the years, and the effect of suppressing leakage loss is reduced. Is likely to decrease. In such a case, in the present embodiment, the damming portion 23 can be replaced, so that the work load of the returning work can be reduced.

<Sixth Embodiment>
Next, a sixth embodiment will be described. The same parts as those of the first to fifth embodiments among the parts of the present embodiment are designated by the same reference numerals, and description of common parts may be omitted.

As shown in FIG. 9, in this embodiment, a stepped seal structure is formed between the seal liner 21 which is a stationary member and the band 5 which is a rotating member. The seal liner 21 has a stepped shape, and has a wall surface facing inward in the radial direction from the upstream to the downstream in the direction of the water flow, a wall surface facing upstream in the water flow in the axial direction, and a wall surface facing in the radial direction. The connection is made in this order so as to form a step, and the band 5 facing the seal liner 21 is also formed with a step.

Between the seal liner 21 and the band 5, a first gap 31 which is located on the upstream side and forms a minute gap in the radial direction is separated from the first gap 31 in both the radial direction and the axial direction, A second gap 32 that is located downstream of the first gap 31 and forms a minute gap in the radial direction, and a first gap 31 that is located between the first gap 31 and the second gap 32. And a second gap 32, and a third gap 33 that is joined to form a bent shape are formed, and each gap forms a seal structure.

Each of the first gap 31, the second gap 32, and the third gap 33 has an annular shape. Further, the radial dimension of the third gap 33 is larger than that of the first gap 31 and the second gap 32.

The damming portion 23 positioned so as to partially fill the third gap 33 is provided in the seal liner 21. In the present embodiment, the damming portion 23 is provided on the wall surface of the seal liner 21 that faces the upstream side of the water flow in the axial direction, but the damming portion 23 is located on the wall surface of the seal liner 21 that faces the radially inner side or the band 5 side. It may be provided.

The leak flow in the first gap 31, which functions as a minute gap, is affected by the rotation of the band 5 and has a circumferential velocity in the same direction as the rotation direction as indicated by an arrow α in FIG. The flow flowing into the third gap 33 also has a circumferential velocity in the same direction as the rotation direction. In the present embodiment, the damming portion 23 that partially fills the third gap 33 damps a leak flow having a circumferential velocity, thereby rapidly decelerating. Thereby, the sealing effect can be improved and the leakage loss can be effectively suppressed.

In addition, although the case where one damming portion 23 that fills the third gap 33 is provided is illustrated in the present embodiment, the number thereof is not particularly limited.

Although the respective embodiments have been described above, the respective embodiments described above are presented as examples, and are not intended to limit the scope of the invention. The novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the scope equivalent thereto.

For example, in the above-described first to fifth embodiments, an example in which the groove 22 and the damming portion 23 are provided in the seal liner 21 that is a stationary member is shown, but the groove 22 may be provided on the band 5 side. .. Further, the groove 22 and the damming portion 23 may be provided on both the rotating member and the stationary member.

1... Francis turbine, 2... Runner, 3... Runner blades, 4... Crown, 5... Band, 5A... Wall part, 6... Lower cover, 7... Side pressure chamber, 10... Casing, 11... Stay vanes, 12... Guide vanes , 20... Seal structure, 21... Seal liner, 21A... Wall part, 22... Groove, 23... Damming part, 23A... End face, 23B... Through hole, 24... Bolt, 25... Bolt hole, 31... First gap , 32... second gap, 33... third gap, C1... rotation axis

Claims (9)

A rotary member that rotates by the pressure of the fluid; and a stationary member that covers the rotary member,
At least one of the wall portion of the rotating member and the wall portion of the stationary member facing each other has a groove extending in the circumferential direction, and a damming portion positioned so as to partially fill the groove. , Fluid machinery. A plurality of the grooves are provided at intervals in the axial direction,
Corresponding to each of the plurality of grooves, the damming portion is provided,
The plurality of damming units are arranged such that at least a part of the damming units located on the downstream side in the flow direction of the fluid is located on the opposite side in the rotation direction of the rotating member from the one located on the upstream side. The fluid machine according to claim 1. The fluid machine according to claim 2, wherein the damming portions adjacent to each other in the axial direction overlap each other in the axial direction. The end surface of the damming portion facing the rotation direction opposite side of the rotation member extends to the rotation direction opposite side of the rotation member as it extends from the upstream to the downstream in the direction of the fluid flow. The fluid machine according to any one of 1. The fluid machine according to claim 1, wherein the groove is inclined so as to extend in the circumferential direction and extend in the axial direction. The fluid machine according to claim 1, wherein the damming portion is fixed inside the groove by a fastening member. A rotary member that rotates by the pressure of the fluid; and a stationary member that covers the rotary member,
Between the wall portion of the rotating member and the wall portion of the stationary member that face each other, a first gap and a second gap that is separated from the first gap in both the radial direction and the axial direction. A third gap that is located between the first gap and the second gap and that is connected to both the first gap and the second gap so as to form a bent shape is formed. Cage,
At least one of the wall portion of the rotating member and the wall portion of the stationary member has a damming portion positioned so as to partially fill the third gap. A rotary member that rotates by the pressure of a fluid, and a stationary member that covers the rotary member, and at least one of the wall portion of the rotary member and the wall portion of the stationary member facing each other is circumferentially arranged. A sealing member used in a fluid machine having a groove extending,
A seal member disposed inside the groove and provided so as to partially fill the groove. A rotary member that rotates by the pressure of a fluid, and a stationary member that covers the rotary member, and at least one of the wall portion of the rotary member and the wall portion of the stationary member facing each other is circumferentially arranged. A method of refurbishing a fluid machine having an extending groove, comprising:
A step of preparing a damming portion,
And a step of providing the damming portion inside the groove so as to partially fill the groove.