DE1750937A1 - Labyrinth seal on a hydraulic centrifugal machine, the runner of which revolves at times in water and at times in air - Google Patents

Description

Bscher Wyee G.m.b.H., Raveneburg (Württemberg)

Labyrinth seal on a hydraulic centrifugal machine whose rotor is sometimes in water and sometimes in air running around.

In hydraulic centrifugal machines, the rotors of which revolve temporarily in water and temporarily in air, for example in Francis turbines, storage pumps or pump turbines, it was previously necessary to use the existing labyrinth seals, which usually have very narrow gaps to cool the operation in air »in order to avoid excessive heating of the interlocking parts. At the Operation in water, this cooling occurs easily through the process water which flows through the gaps, so that3 additional measures are not required.

The simplest and most obvious method for cooling the labyrinth seals during operation in air, namely introducing water into the labyrinth gap, has the disadvantage that considerable energy losses occur, which, depending on the gap wedge and the amount of water introduced, between 1 and 2% of the nominal output of the hydraulic Machine

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can be. Despite these high losses, the introduction of water was absolutely necessary with the previously known designs of the labyrinth seals. especially since it had to be feared that the stationary and rotating parts of the labyrinths would practically not be closed as a result avoidance of misalignment, also because of the required bearing clearance, the possible deformations and Displacements of the housing etc. could rub against each other and seize in the process.

The invention is now based on the object, in a labyrinth seal on a hydraulic centrifugal machine, whose impeller revolves at times in water and at times in air, to take measures that make it possible under There is no need for additional cooling while circulating in air. Metallic contact between the sealing gap limiting parts and excessive heating.

According to the invention, this object is achieved in that the relative position of the parts delimiting the sealing gap on both sides of one for the rotation of the rotor in Water-specific position, in which the width of the sealing gap is relatively small, up to a position with enlargedi intended for the runner to circulate in the air Gap is changeable. This can be brought about, for example, by the fact that the sealing gap that does not run around

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limiting part slidably guided in the machine housing and connected to one or more servomotors via intermediate links, for example adjusting rods or the like is. In this way it is possible to move this part into the working position when the runner rotates in water and so to form the required narrow sealing gap. If the machine is to be operated in air, this will be adjustable part with the help of the servomotors so far moved until a sufficient expansion of the sealing gap entry. In addition, by suitably designing the relevant part, for example by attaching Attacks or the like. Ensure that the parts can only move together so far that the intended working position is adhered to. Because of the small clearance it is advantageous if the movable part always occupies the same position in the working position and is held motionless in the machine housing. This can can be brought about, for example, by a conical stop which limits the adjustment path in the direction of the gap. The part of the labyrinth seal that can be moved to operate de3 required servomotors can be designed in any known manner. For example, ej is possible to use hydraulically or pneumatically operated servomotors or & uch simple lever mechanisms or

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Electrically driven spindles.

When operating a hydraulic rotary machine with the According to the invention labyrinth seal, it is essential that the seal gap during the change the relative position of the parts delimiting the sealing gap on both sides is watered. The water flow of the The sealing gap and thus the cooling that may be necessary should only be interrupted when the parts delimiting the sealing gap on both sides are in relation to one another are in a position in which the width of the sealing gap is large enough to allow these parts to strip against one another to be avoided with certainty.

With the inventive design of the labyrinth seal it is possible to reduce the performance loss of the hydraulic machine during operation in the emptied state, i.e. So when the runner goes around in the air, it has to be lowered significantly. This is due to the fact that the mentioned Loss of performance occurs mainly as a result of the previously required irrigation of the gap and the impeller disc friction. When using the concept according to the invention, there remains a loss of performance - apart from the Frictional losses in the bearings - only the drive power required to ventilate the air.

Apart from reducing the power loss, the

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But also the construction of the labyrinth seal according to the invention still other advantages with eich. Pump storage batteries more common As is well known, the Hegel construction consists of an electrical machine that operates as a generator and ala motor can be, as well as a turbine and a storage pump. During the turbine operation, i.e. during of peak metropolitan production, becomes the storage pump in the Hegel disconnected because of the loss of power in air with irrigated labyrinth seals moving along. Storage pumps are so high that economic viability is often questionable is posed. Cases are also known in which analogously a for the same reason during the pumping operation Turbine is disconnected. In the case of blind rental business (Phase shift operation) is also used to reduce The storage pump is often disconnected due to the losses, whereby the impeller of the turbine rotates in air or depending on the Construction is also uncoupled. The mechanical and structural effort as well as the effort for the control of the clutches required is considerable. Abgejehea From this, however, there is also the need to equip each of the three machines of the Fumpapeichereatzee with two bearings equip. Furthermore, it is required if very short switching times between the individual operating modes desired between the electric masohine and

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to install a start-up turbine or a hydraulic coupling for the storage pump to start up the storage pump quickly. These devices, the clutches, launch turbines, hydraulic clutches and a certain number of bearings can be omitted if the erfindungagemäase Conception is applied. This means that a pumped storage unit can be used on three main machines, namely the electric machine, the turbine and the storage pump are limited, taking into account the most efficient arrangement, a common shaft and two bearings for three machine units suffice. As a further consequence of the simplification compared to the conventional construction method, the significantly lower space requirement and the correspondingly lower construction costs must be mentioned brings with it.

One with the labyrinth seal constructed according to the invention The pump storage set provided allows shorter changeover times between the individual operating modes than the was to be realized with conventional construction. This results from the following:

During turbine operation a the storage pump runs in Air; During the pumping operation the turbine runs in air; the operational setting · from turbine operation to pumping operation and vice versa can only be achieved by the mutual filling and emptying of the hydraulic machine in question

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take place.

In phase follow-up operation, both are hydraulic Maachines emptied. The storage pump can go from a standstill in a water-filled state or in an emptied state can be started up directly by starting up the turbine.

In the case of the pump turbine, the subject matter of the invention can also be used advantageously. Da3 start-up for pumping operation is usually carried out in a known manner with the aid of a separate, rigidly coupled electric motor with the pump turbine empty, with the impeller rotates in air. The size or the design of the start-up motor also depends, among other things, on the power loss in air rotating impellers. With the inventive concept the labyrinth seal, the losses can be substantial reduce, aodasa the high-lift motor can be designed for a lower output. This is specifically then of Interest if enough time is available to start up the pump operation, with the acceleration torque to be applied the motors can be relatively small. In addition, the losses during phase shifter operation, which is known when the pump turbine is empty takes place, can be greatly reduced.

In the drawing are exemplary embodiments of the invention

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left labyrinth seal shown on a hydraulic centrifugal machine. Show it

Fig. 1 is a hectic longitudinal section through the centrifugal machine in the area of the labyrinth seals, wherein the parts delimiting the sealing gap are intended for the rotation of the rotor in water Location, and

Fig. 2 shows the same longitudinal section, but with the parts delimiting the sealing gap in the for the Circulation of the rotor in the air are certain position.

The hydraulic centrifugal machine shown only partially in the drawing can be a Francis turbine, a centrifugal pump or a pump turbine. Runner 1 is on the hub side with the help of a comb-like designed labyrinth seal 2 and on the rim side with the help of a stair-step-like labyrinth seal 3 against the stationary Parts 4, 5 and 6, 7 of the housing sealed. The comb-like seal 2 has only one side of the combs a sealing gap 8 while on the other Side a larger gap 8 · is located. The sealing gap of the labyrinth seal 3 is designated by 9.

On the housing side, the sealing gaps 8 and 9 are axially displaceable in the housing through non-circumferential

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share 5 or 7 guided T ^ iIe 10 or 11 limited, the Via intermediate members 12 each are connected to one or more hydraulic or pneumatic servomotors 13. 14 are seals on the guide surfaces designated 16 the housing parts 5 and 7 designated. Runner side the boundaries of the sealing gaps 8 and 9 are immediate by corresponding parts 15 of the rotor hub or the Runner wreath formed.

Each of the servomotors 13 consists of a housing 17 and a sliding element with the relevant intermediate member 12 firmly connected piston 18. On both sides of the piston 18, spaces 19 and 20 are present in the housing 17, which through channels 21 and 22, e.g. via control valves (not shown) can be connected to a pressure medium source. The parts 10 and 11 can with the help of the actuators 13 in axial direction of the machine between two end positions, one of which is in Pig. 1 and the other in Pig. 2 is shown.

The end position according to FIG. 1 is for normal operation the machine determines which runner 1 rotates in water. The width of the sealing gaps 8 and 9 is included relatively small. To make sure at everyone the seals 2 and 3, the displaceable parts 10 and 11, both in the axial and in the radial direction, always the

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occupy the same position, each of these parts is with one centering stop equipped., which is provided with a conical surface 24, which is in the position of FIG a corresponding conical surface 23 of the housing part 4 or 6 and thus ensures a play-free connection with the Uaachinengehäuae.

The parts UO and 11 are designed as annular pistons and limit in the position according to FIG. 1 with the housing 4, 5 or 6, 7 each have an annular space 23t which is connected to the pressurized water space 27 of the machine via one or more channels 26 stands. This measure causes parts 10 and 11 when operating with water in the position according to FIG. 1, they are automatically pressed against the stop surfaces 23 of the housing by the water pressure in the annular spaces 25. The servomotors then only have to be designed for generating the displacement forces.

For operation with the rotor 1 rotating in air, the parts 10 and 11 are brought into the position shown in FIG. 2 with the aid of the servomotors 13. As can be seen, the sealing gaps 8 and 9 are delimited by stepwise stepped cylindrical surfaces. In the position according to FIG. 2, the parts 10 and 11 are shifted away from the rotor 1 in the axial direction by an amount corresponding approximately to the axial length of a step _{with B e train.}

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The gap width has thus increased by the amount of a step height. The danger of a streak of Sealing parts 15 of the rotor 1 on the non-rotating sealing parts 10 and 11 is therefore under all circumstances switched off, and a much smaller one also occurs Heating of the air in the gaps than they arise with the narrow sealing gaps in the position according to FIG. 1 would.

In order to irrigate while the parts 10, 11 are being moved To enable the sealing gap 8 and 9, respectively, one leading to the sealing gap 8 and 9 is in the parts 10, 11 Channel 28 is provided which is in communication with a longitudinal bore passing through the intermediate member 12. The longitudinal bore in the intermediate member 12 is in turn with it a space 29 recessed in the servomotor housing 17 in connection, which through an opening 30 from the outside with pressurized water can be charged.

The supplied pressurized water passes through the bore in the intermediate member 12 and the channel 28 as a coolant to the sealing gap 8 or 9 · The water supply should be removed when the sliding Parts 10, 11 of bishop 1 continue until the situation is correct for Pig. 2 is reached, the gap is enlarged has been. Conversely, when the parts 10, 11 are returned to the position according to FIG. 1, the pressurized water supply may only be reduced.

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will be broken when the hydraulic gyroscope for the actual operation has been filled with water.

A change in the width of the sealing gap 8 or when moving parts 10 or 11, this would also be achieved if the sealing gap 8 or 9 instead of, as described, would be limited by stepwise stepped cylindrical surfaces, by conical surfaces. One for the operation of the Runner in air sufficient width of the sealing gap would then possibly be achieved with a smaller change in position of the displaceable part than with the stepwise offset boundary surfaces.

Labyrinth seals with sealing gaps delimited by conical surfaces have, however, especially in practice in large hydraulic machines, proved to be inexpedient because their sealing effect is already lower at low axial displacement of the rotor changes noticeably. There can be a constant change in the width of the in operation Dichtaepaltes and thus also the efficiency of the Machine and the axial thrust result. For this reason, in a labyrinth seal according to the invention, step-wise stepped cylindrical-like boundary surfaces are used for the Sealing gap is preferable to conical boundary surfaces.

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Claims (7)

- 13 claims 1. Labyrinth seal on a hydraulic centrifugal machine, whose rotor is sometimes in water and sometimes in air circulates, characterized, that the relative position of the sealing gap (8 or 9) on both sides delimiting parts (10, 15 or 11, 15) of the for the rotation of the rotor (l) in the water (Fig. 1), in which the width of the sealing gap (8 or 9) is relatively small, up to a position intended for the rotor (1) to circulate in the air with an enlarged position Gap (Fig. 2) is changeable. 2. A method for operating a hydraulic centrifugal machine with a labyrinth seal according to claim 1, characterized characterized in that the sealing gap (8 or 9) during the change in the relative position of the sealing gap both sides delimiting parts (10, 15 or 11, 15) is watered. 3. Labyrinth seal according to claim 1, characterized in that the non-circumferential, the sealing gap (8 or 9) delimiting part (10 or 11) in the machine housing (4, 5 or 6, 7) slidably guided and via intermediate links 209815/0338, BATH ORIGINAL. (12) connected to one or more servomotors (13) is. 4. Labyrinth seal according to claim 3, characterized in that the sealing gap (8 or 9) is stepped off cylindrical surfaces is limited and the displaceable part (10 or 11) of the seal by approximately the amount corresponding to the axial length of a step is displaceable in the axial direction. 5 · Labyrinth seal according to claim 3 or 4, characterized in that that the movable part (10 or 11) of the seal is equipped with a centering stop (24) which ensures a backlash-free connection with the machine housing (4.5 or 6.7) with a small gap width. 6. Labyrinth seal according to one of claims 3 to 5, characterized in that the displaceable part (10 or 11) the seal is designed as an annular piston and in the position intended for the rotor (l) to rotate in water the housing (4, 5 or 6, 7) delimits an annular space (25) connected to a pressurized water source. 7. labyrinth seal according to claim 6, characterized in that the annular space (25) with the pressurized water space (27) of the hydraulic machine is in communication. 209815/0338 BATH ORIGINAL Blank page