US20130330169A1

US20130330169A1 - Water Turbine

Info

Publication number: US20130330169A1
Application number: US13/639,536
Authority: US
Inventors: Manfred Stummer
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2011-01-18
Filing date: 2011-11-10
Publication date: 2013-12-12
Also published as: EP2516868B1; WO2012097839A1; DE102011008869A1; EP2516868A1

Abstract

The invention relates to a water turbine or water pump or other hydraulic machine that comprises a stationary and a revolving component. The invention also comprises a sealing gap that is disposed between the stationary and revolving components, which is sealed by a labyrinth seal and through which a leakage flow for cooling or lubricating the seal will flow during operation of the hydraulic machine. The invention also provides a connection on the sealing gap for its evacuation.

Description

FIELD OF THE INVENTION

The invention relates to a water turbine, a pump turbine or a water pump. It especially relates to the field of labyrinth seals and the blade wheel. Reference is hereby made to DE 198 08 877 A1 for such a hydraulic machine.

BACKGROUND

In such machines, a blade wheel revolves within a fixed housing, so that a gap is produced between the two. The gap needs to be sealed against leakages in order to minimize leakage flow to the highest possible extent. Labyrinth seals are known for sealing. They are available in a large number of configurations. The simplest form is the so-called smooth labyrinth, in which the boundary walls of the clearance gap are free from discontinuities and extend more or less parallel next to one another. A further embodiment is the so-called stepped labyrinth in which the mutually cooperating surfaces are arranged in a stepped manner. Furthermore, numerous labyrinths are known which comprise a large number of small annular chambers and channels in the shape of annular gaps which connect the chambers with one another. The invention relates to such a generic labyrinth seal. Such known labyrinth seals are disclosed for example in DE 1 551 223 A, DE 18 92 39 C and U.S. Pat. No. 5,924,844.
DE 1 807 443 describes a method and a device for operating a pump turbine installation which is operated temporarily without any working medium (which is water). In order to seal the leakage flow between the blade wheel and the suction pipe of the pump and the turbine and for sealing between the blade wheel and the remaining housing, stepped labyrinths or smooth labyrinths are used. In order to reduce the power loss of the pump turbine installation, whereas those of the turbine will be maximized. The blade wheel of the turbine will then revolve in air. In turbine operation, the gap widths of the labyrinth seals of the turbine will be minimized conversely, and those of the pump will be maximized, with the pump blade wheel then also revolving in air. In the transition from pumping to turbine operation or vice versa, the entire turbine shaft with the pump and turbine blade wheel will be displaced in the axial direction.
In hydraulic machines of the kind mentioned above, the problem of power loss, which is especially high, will occur when the machine is discharged and is therefore not filled with water but with air. These losses are largely caused by the friction of air in the gap of seals, e.g. labyrinth seals between the blade wheel and stationary components.
The water-free state occurs especially in a set of machines which comprises a water turbine and a water pump which are disposed on one and the same shaft and are coupled with one another in a torsion-proof way, as is the case for example in storage power stations. One of the machines is filled with water during a specific period of time, whereas the other revolves in air.
The invention is based on the object of providing a machine according to the preamble of claim 1 in such a way that no-load losses where water does not flow through the machine are minimized.

SUMMARY

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed innovation. This summary is not an extensive overview, and it is not intended to identify key/critical elements or to delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.
The subject matter disclosed and claimed herein, in one aspect thereof, comprises a water turbine or water pump or other hydraulic machine that comprises a stationary and a revolving component. The invention also comprises a sealing gap that is disposed between the stationary and revolving components, which is sealed by a labyrinth seal and through which a leakage flow for cooling or lubricating the seal will flow during operation of the hydraulic machine. The invention also provides a connection on the sealing gap for its evacuation.
Accordingly, the entire blade wheel region or at least the sealing gap will be evacuated in the work-free phases of the machine. A connection for applying a negative pressure will therefore be associated to each or at least one sealing gap or the entire blade wheel region. The connection is disposed at a respective location which allows efficient evacuation of the sealing gap, e.g. at the guide wheel ring or the cover of a water turbine or a water pump. The evacuation can occur intermittently. It can be automated in that a suction device will only be activated during idle running of the machine and is deactivated again during the working phases.
In a preferred embodiment, the evacuation can occur completely or partly. If required for cooling the involved component, the evacuation can be interrupted and can be replaced by venting of the sealing gap. The evacuation and venting can occur cyclically and can be controlled automatically.
In addition to the measure disclosed in claim 1, the width of the sealing gap can also be changed, as defined in claims 2 through 8 and as shown in FIGS. 2 a through 4 b. The measures as described and illustrated therein can be applied. This is not mandatory however.
The invention offers considerable progress. For example, losses of up to 1% of the nominal power of the machine can be saved.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the disclosed innovation are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles disclosed herein can be employed and is intended to include all such aspects and their equivalents. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an axial sectional view of a Francis turbine in an axial sectional view in accordance with the disclosed architecture.

FIGS. 2 a and 2 b illustrate a perspective view of different embodiments of the labyrinth seal In an operating position and a non-operating position of the stationary component in accordance with the disclosed architecture.

FIGS. 3 a and 3 b illustrate an enlarged schematic illustration of the detailed view A of the labyrinth seal of FIG. 1 in accordance with the disclosed architecture.

FIGS. 4 a and 4 b illustrate an enlarged schematic illustration of the detailed view B of the labyrinth seal according to FIG. 1 in accordance with the disclosed architecture.

DESCRIPTION OF PREFERRED EMBODIMENTS

The innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding thereof. It may be evident, however, that the innovation can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate a description thereof.
The Francis turbine shown in FIG. 1 comprises a blade wheel 8 as the main element, a guide wheel ring 9, turbine cover 10, a suction pipe 11 and a scroll case 12. The blade wheel 8 comprises a blade wheel crown 8.1, a blade wheel rim 8.2 and a plurality of blades 8.3. It is arranged in a torsion-proof manner with the turbine shaft 14 which revolves about a rotational axis 13.
A labyrinth seal 3 is arranged between the blade wheel 8, the guide wheel ring 9 and the suction pipe 11 (detailed sectional view A), and the blade wheel 8 and turbine cover 10 (detailed sectional view B). Each of the two labyrinth seals 3 comprises a stationary component 1 and a revolving component 2, which are arranged in the present case in a concentric manner in relation to the rotational axis 13 of the turbine shaft 14 of the blade wheel and in the manner of a circular ring.
The relevant parts of the invention are the vacuum connections 20 and the feed lines 21. A vacuum channel 21 which extends from the outside to the inside is disposed in the suction pipe 11. The vacuum connection 20 is disposed on the outside surface of the other end of the suction pipe 11 (see detailed sectional view A).
A further vacuum connection 20 with vacuum line 21 is associated with the labyrinth seal 3 in the detailed sectional view B. In this case, a vacuum channel 21 extends through the turbine cover 10.
The two FIGS. 2 a and 2 b show the precise configuration of the two components 1 and 2 of the labyrinth seal 3 in accordance with the invention in detail.
Recesses are incorporated in the two components 1 and 2. The boundary surfaces 1.1 and 2.1 of the two components 1 and 2 which are produced in this manner form annular chambers 4 with one another in this case and channels 5 which are shaped in the manner of annular gaps and which connect said chambers in a conductive manner with one another.
The mutually facing boundary surfaces 1.1 and 2.1 of the two components 1 and 2 of the labyrinth seal 3 extend in a conical manner in FIG. 2 a, thus leading to a stepped labyrinth. In the illustration according to FIG. 2, they are cylindrical (smooth labyrinth). Furthermore, the chambers 4 could merely be provided in one of the components, e.g. exclusively in the rotating or in the stationary component, both in the conical and also in the stepped configuration of the two components 1 and 2. This is not mandatorily necessary however.
The respective left-hand illustration in two drawings of FIGS. 2 a and 2 b shows the initial position of the stationary component 1 in relation to the revolving component 2. This corresponds to an operating position in which the labyrinth seal 3 of the hydraulic machine allows a defined leakage flow of working medium. In contrast to this, the respective right-hand illustration in the two drawings 2 a and 2 b shows a position in which the stationary component 1 is displaced in relation to the revolving component 2 in the direction of a leakage flow, which means in the axial direction.
The two components have an enlarged mutual radial distance (non-operating position). As is shown in FIGS. 2 a and 2 b, the gap width of the annular-gap-shaped channels 5 is increased considerably in the non-operating position in particular. It now allows air to flow through the enlarged gap width instead of the conventional working medium when the working medium has been switched off. The air flowing through the blade wheel of the hydraulic machine which now revolves in air ensures on the one hand that ventilation losses are avoided and on the other hand that the labyrinth seal is cooled in this case exclusively by the air moved in this manner.
The change in the gap width is therefore caused by the fact that the two components 1 and 2 have a stepped configuration on their mutually facing surfaces. In the embodiment according to FIG. 2 b, this concerns regular steps. In the right-hand illustration of FIG. 2 b it can be seen that the respective projections of the one component correspond to the gaps of the other component.
FIGS. 3 a and 3 b show an enlarged illustration of a labyrinth seal in accordance with the invention according to the detailed view A as shown in FIG. 1. The left-hand illustration according to FIG. 3 a corresponds to the operating position, whereas the illustration according to FIG. 3 b corresponds to the non-operating position of the stationary component 1. In this case, the stationary component 1 is arranged as a so-called split ring 6. The latter is associated with a displacing device in order to displace the split ring between the operating position and the non-operating position.
In the present case, the displacing device comprises a piston which is formed by the split ring 6 itself, with the piston partly delimiting a first piston chamber 7.1 and a second piston chamber 7.2 (together with the guide wheel ring 9 and a suction pipe 11). In the present case, the split ring 6 is enclosed between the blade wheel 8, which acts in this case as the revolving component 2, and the guide wheel ring 9.
The two piston chambers 7.1 and 7.2 are connected with a pressure supply (not shown) via an indicated feed line in order to selectively supply the two piston chambers 7.1 and 7.2 with pressure medium. When the piston chamber 7.1 is pressurized alone, the split ring 6 is displaced upwardly in the position as shown in FIG. 3 a (i.e. in the operating position), whereas when the piston chamber 7.2 is pressurized alone it is moved in the direction towards the non-operating position. The end positions are mechanically limited by limit stops.
FIGS. 4 a and 4 b show an enlarged schematic illustration of the labyrinth seal of FIG. 1 in accordance with the invention in the detailed view B. FIG. 4 a shows the operating position, whereas FIG. 4 b shows the non-operating position of the stationary component 1. It can be seen that the split ring 6 is enclosed by the turbine cover 10 and a further split ring 16 which revolves together with the blade wheel 8. Both split rings 6 and 16 can be exchanged relatively simply in case of wear and tear. In order to prevent passage of pressure medium from the piston chambers 7.1 and 7.2, seals can be provided between the split ring 6 and the turbine cover 10, as shown in the preceding drawings. Further, a vacuum connection 20 is indicated in all FIGS. 2 a to 4 b.
Instead of the illustrated displacing device, the split ring 6 could also be actuated magnetically, electrically, electromagnetically or mechanically. In the latter case it is possible to use actuating drives, threaded spindles or the like for this purpose.
The following advantages are achieved by the invention: In the case of hydraulic machines in which the blade wheel is blown out, which means it revolves in air and its pressure corresponds to the applied underwater pressure, the ventilation losses are approximately 1% of the nominal power of the hydraulic machine. In atmospheric air the ventilation losses are approximately 0.5% of the nominal power.
The aforementioned ventilation losses can approximately be broken down as follows:

- ¼ is caused by ventilation of the blade wheel in air, and
- ¾ is caused by the labyrinth seal cooled with water.

As already mentioned above, the two measures can be applied, which means the evacuation of the entire blade wheel region or a part thereof as well as the enlargement of the gap width, respectively in non-operation. In any case, the friction and ventilation losses are effectively minimized.
The air circulation in the labyrinth seal will be improved by enlarging the gap width in the non-operation of the hydraulic machine, which occurs when no water impinges on its blade wheel. As a result of the relatively large gap width (the stationary component is in its non-operating position), the air friction between the revolving component and the air will be minimized, leading to a lower development of heat in the labyrinth seal.
The maximum gap width of the labyrinth seal will preferably be chosen in such a way that in non-operation of the hydraulic machine without water cooling of the labyrinth seal the same cooling performance is achieved by air cooling as with the leakage flow of water. In other words, the gap width will be set in such a way that the (convective) mean heat transmission coefficients of the stationary and/or revolving component are substantially equal with respect to the surrounding medium both in operation (operating position of the stationary component) of the hydraulic machine and also in non-operation (non-operating position of the stationary component).
Ventilation losses can be reduced substantially with the labyrinth seal in accordance with the invention. Both air friction and the development of heat will simultaneously be reduced to a considerable extent in this process, despite the fact that the labyrinth seal will exclusively be cooled with air in non-operation.
The solution in accordance with the invention provides the following advantages: both the production effort and the operating costs are reduced in comparison with known machines;

- the power loss of the machine is reduced; and
- cooling of the labyrinth seal is optimized.

If an installation comprises two or more labyrinth seals which have a common shaft, the labyrinth seals can be displaced selectively for each machine into the one or the other position, i.e. the operating position or non-operating position. As a result, the labyrinth seals of all machines or some machines can be brought to one and the same position.
This also applies to the case of one single machine with two labyrinth seals which are disposed on the same shaft. The invention can also be applied to seals with smooth (non-stepped) sealing gaps.
What has been described above includes examples of the claimed subject matter. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.

LIST OF REFERENCE NUMERALS

1 Component
2 Component
3 Labyrinth seal
4 Chamber
5 Channel
6 Split ring
7 Piston
7.1 First piston chamber
7.2 Second piston chamber
8 Blade wheel
8.1 Blade wheel crown
8.2 Blade wheel rim
8.3 Blades
9 Guide wheel ring
10 Turbine cover
11 Suction pipe
13 Rotational axis
14 Turbine shaft
16 Split ring
20 Vacuum connection
21 Vacuum channel

Claims

What is claimed is:

1. A water turbine comprising:

a stationary component and a revolving component;

a sealing gap disposed between the components, through which a leakage flow for cooling and lubricating will flow during operation of a hydraulic machine; and

at least one connection is provided for a complete or partial evacuation of an entire blade wheel region or at least one of a sealing gap in work-free phases of the water turbine.

2. The water turbine of claim 1, wherein the sealing gap is arranged as a

labyrinth seal and comprises a plurality of annular chambers and channels

which are shaped in a manner of an annular gap and which connect said

plurality of annular chambers in a conductive manner with each other; and

wherein the stationary component is displaceably held in an axial direction relative to the revolving component between an operating position and a non-operating position in a direction of the leakage flow for setting a gap width of the channels shaped in the manner of the annular gap.

3. The water turbine of claim 2, wherein an axial extension of the plurality of annular chambers in a direction of displacement of the stationary component is larger than an axial extension of the channels shaped in the manner of the annular gap.

4. The water turbine of claim 3, wherein mutually facing boundary surfaces of the stationary and revolving components form the labyrinth seal, and are disposed on a cylinder or cone jacket surface, and both stationary and revolving components are arranged concentrically with respect to each other.

5. The water turbine of claim 4, wherein the stationary component is arranged as a split ring and comprises a displacing device or is connected to a displacing device, wherein the displacing device displaces the split ring between the operating position and the non-operating position.

6. The water turbine of claim 5, wherein the displacing device for displacing the split ring can be actuated magnetically, electrically, electromagnetically, pneumatically, hydraulically or mechanically.

7. The water turbine of claim 5, wherein the displacing device comprises a piston which is formed by the split ring and the piston at least partly delimits a first piston chamber and a second piston chamber, with both piston chambers being pressurizable in an alternating manner via a pneumatic or hydraulic pressure supply.

8. The water turbine of claim 7, wherein various labyrinth seals can be brought to the operating position or non-operating position independently from one another or together with one another.

9. The water turbine of claim 8, wherein a vacuum connection is arranged in or on a suction pipe or a pressure pipe of the hydraulic machine.

10. The water turbine of claim 9, wherein the vacuum connection is arranged in a region of a guide wheel ring or a housing cover.

11. The water turbine of claim 10, further comprising a device for activating an evacuation depending on the operating state of the hydraulic machine.

12. The water turbine of claim 11, further comprising a device for automatically blocking the sealing gap after applying the vacuum connection.