EP1871992A1

EP1871992A1 - Device and method for reducing loss through sealing gaps in turbomachines

Info

Publication number: EP1871992A1
Application number: EP06724503A
Authority: EP
Inventors: Klaus-Peter Priebe
Original assignee: Priebe Klaus-Peter
Current assignee: Deutsche Energie Holding GmbH
Priority date: 2005-04-21
Filing date: 2006-04-21
Publication date: 2008-01-02
Also published as: DE102005018716A1; WO2006111405A1

Abstract

The invention relates to a device for reducing loss through sealing gaps in turbomachines, said device comprising a housing (101, 201, 301, 401, 501) containing a rotary body (106, 206, 306, 406, 506). At least one labyrinth seal (110, 210, 310, 410, 510) is arranged between the housing (101, 201, 301, 401, 501) and the rotary body (106, 206, 306, 406, 506). The rotary body (106, 206, 306, 406, 506) and/or the housing part (120) carrying a fixed part (111, 211, 311, 411, 511) of the at least one labyrinth seal (110, 210, 310, 410, 510) are embodied in an axially mobile manner such that the width of the gap of the at least one labyrinth seal (110, 210, 310, 410, 510) can be adjusted by displacing the rotary body (106, 206, 306, 406, 506) and/or the housing part (120).

Description

APPARATUS AND METHOD FOR REDUCING SEAL LOSS OF TURBOMA MACHINES

The invention relates to a device for reducing sealing gap losses of turbomachinery with a housing and a rotational body arranged therein, wherein between housing and. Rotational body at least one labyrinth seal is arranged.

The state of the art is characterized in that the gap losses between housing and impeller are reduced by mechanical seals, labyrinth seals or even brush-like seals today.

In small turbines or loaders today, preferably the gap between the housing and the open impeller is left open with the smallest possible dimensioning of the gap. The dimensioning of the tolerated gap is essentially dependent on the temperature range to be traversed between idle state and operating state with a corresponding expansion of the rotor and the working shaft and the centrifugal forces generated at the turbine or compressor wheel.

As a rule, the turbine or compressor wheel will stretch before the housing can follow the thermal expansion. This thermal and centrifugal expansion of the impellers can use at temperatures up to 200 ⁰ C well within the range of 0.2 mm are, in small hot gas turbines also quite in the range of 1.0 to several millimeters.

In order to avoid a destructive mechanical contact between the wheels and the housing, today the gap between the housing and the wheels is replaced by accepting the resulting

BESTATIGUNGSKOPIE Lusts relatively large dimensions and the thermal loading of the turbine or compressor system is carried out gradually such that the housing has sufficient time for thermal expansion. Thus, a turbine of today's design can only follow thermal load changes slowly. The losses through the gap increase very rapidly with decreasing impeller diameters and the mechanical efficiency of the impeller decreases rapidly.

However, sealing systems are also used, e.g. Mechanical seals, which are mounted on the rotating body and must be mounted under high pressure gradient between the flow inlet and outlet under bias to the shaft. Mechanical seals thus cause considerable frictional resistance and are subject to wear.

Labyrinth seals are preferably placed in the axial direction on the rotating axis, which are formed as a simple or interlocking comb. The constructive distance between the slats must take into account thermal expansions and unavoidable imbalances or unevenness. For small turbines as well as for compressed air tools, gaps in the size of up to 0.1 mm are realized as minimum sealing gap widths between the lamellae. For hot gas turbines, the distances may well be in the range of a few millimeters.

Brush-like seals attach to the brush ends on the shaft. However, the flow medium can flow through between the individual brushes to a small extent. Brush seals are susceptible to contamination resulting in increased spacing between the brushes, possible abrasive traces of contaminants, and are not applicable to large pressure gradients. The object of the invention is to provide a device for reducing gap losses and thus to increase the efficiency of turbomachinery.

With a device of the type described, this object is achieved in that the rotational body and / or a fixed part of the at least one labyrinth seal bearing housing part is axially displaceable, so that the gap width of the at least one by displacement of the rotating body and / or the housing part Labyrinth seal is adjustable. In this way, the rotary body or a part of the housing is mounted in each case axially movable with a radial labyrinth seal engagement against the second part of the labyrinth seal.

Thus, the sealing gap width can be adjusted by an axial displacement to a desired value. Also, this value is not rigid, but can be changed during operation, so that it is possible in particular to start the turbine with larger sealing gaps and only on reaching a steady state operating the sealing gaps to the smallest possible extent to reduce the efficiency of Maximize machine. In this way, damage to the machine during startup is avoided because, due to the operating conditions occurring here, contact between the rotating and stationary parts of the machine could occur if the sealing gap diameters are too small and can be effectively prevented by the invention ,

Thus, the invention is used to reduce the gap occurring between housing and turbine or compressor blade rotating body occurring. For this purpose, either the normally to the housing freely rotating Tur- binenschaufelenden a conventional radial turbine provided with a lateral surface, said lateral surface at the upper and / or lower end carries a part of the labyrinth seals and the opposite housing part the respective other corresponding part of the labyrinth seals or provided perpendicular to the direction of rotation base with the large radius of the impeller and the opposite housing part carries corresponding labyrinth seals.

The effective sealing gap height after run-up of the rotating body can thus be reduced according to the invention to a width of a few 0.001 mm and the flow losses through the sealing gap and the secondary flow losses can be drastically reduced.

Further advantageous embodiments emerge from the subclaims:

It can thus be provided that at least one sensor element is provided for determining at least the axial position of the rotary body and / or the displaceable housing part. This makes it possible to achieve a particularly effective control of the sealing gap, since the current position of the rotary body or of the displaceable housing part can be determined at any time.

It is advantageous if at least one electronic control arrangement for axially positioning the rotary body and / or the displaceable housing part is provided depending on the measured sensor information in an embodiment of the invention. In this way, in particular in interaction with a sensor element, a fully controlled sealing gap width can be achieved to the desired extent. Depending on the measured position, the axial position of the rotary body or of the housing part can be any be tracked time to fix the sealing gap to the desired level. In particular, if over time thermal expansions of the shaft or the housing part occur or thermal load changes with consequent changes occur, this is automatically compensated by the control, without the efficiency of the machine deteriorates or damage occurs.

It is advantageous if the rotary body is mounted electromagnetically and / or is designed to be axially displaceable by electromagnetic means.

The device according to the invention is preferably carried out with an electromagnetically actively mounted rotary body (impeller), which is equipped with an electromagnetic imbalance compensation and which can be displaced axially, for example in a range of ± 2.0 mm with an accuracy of 0.001 mm. The axial thrust is brought about by a corresponding current application of the electromagnetically active thrust bearing. This design is useful when the rotation body is a very fast rotating body, which can no longer be stored sensibly by mechanical bearings.

In the case of an alternative mechanical mounting, the invention can be carried out in such a way that the housing is equipped with a membrane with an axially displaceable cover and this cover is axially displaceable via a mechanical or electromechanical adjusting device. This design is suitable for all rotary bodies whose speeds are below 20,000 rpm.

The combination of the electromagnetically movable shaft and axially displaceable housing parts lends itself to the Case that a multi-stage turbine and / or compressor concept is followed with different temperature stresses of the individual wheels.

It is advantageous for the respective distance between wheels and corresponding housing parts to be sensed with a high degree of accuracy in the range of 0.001 mm, and the gap between the housing and the running wheels to be controlled to the smallest possible extent via a regulator. This technique according to the invention also makes it possible to keep the gap loss small during the run-up of the turbine and / or the compressor.

Advantageously, the labyrinth seal is used in conjunction with an axial positioning of the shaft or the housing in an axial turbine or an axial compressor.

It may also be advantageous that the labyrinth seal can be used in a radial turbine or a radial compressor in conjunction with an axial positioning of the shaft and / or the housing.

Alternatively, the labyrinth seal can be used in conjunction with an axial positioning of the shaft or housing in a diagonal turbine or a diagonal compressor.

The labyrinth seal may expediently be provided on two axisymmetric circular segment-shaped surfaces around the center of mass of the rotational body and the labyrinth seal each have labyrinth webs spaced from one another on the housing part and the rotational body, wherein the distance of the labyrinth webs is dimensioned such that the working shaft exerts a free precession movement. can lead. Thus, the bearing the labyrinth seals surfaces of the impeller and the opposite housing parts according to the invention can be designed such that when the precession of a fully electromagnetically mounted working shaft, these interlocking surfaces are located on a circular segment around the center of mass of the working shaft. Also, such precession movements do not result in contact between the rotating and stationary parts of the labyrinth seal.

Particularly advantageously, the sensors are designed as non-contact sensors. In the case of the high rotational speeds of the rotating body, a position determination of the body in the housing via a contactless sensor system is recommended. In particular by means of induction sensors can be achieved particularly advantageous results.

Very good results are obtained when, according to the invention, the rotary body can be moved to a sealing gap width between 0.1 and 0.005 mm. In this area, the sealing gap losses are also in small machines in a range that does not affect the efficiency of the machine excessively.

In an embodiment, it can be provided that a housing cover enclosing the rotary body at least partially is provided, on which a stationary part of the labyrinth seal is arranged and which is connected to the housing with a pressure-resistant membrane and is designed to be mechanically or electromechanically movable axially. Such mechanical adjustment of the gap width, as stated, in machines whose speed moves in the lower to middle range, be appropriate. In an advantageous embodiment of the invention it is provided that the rotary body partially carries turbine blades, which have an outer circumferential surface, which are formed as part of an upper and / or lower radial labyrinth seal. In this way, the seal can be integrated directly into the turbine blades and thus carried out a seal directly on the edge of the turbine wheels, whereby the structural complexity is reduced and additional seals can be avoided.

A further embodiment of the invention provides that in the presence of more than one labyrinth seal between the rotary body and the housing, the sealing gaps of the individual labyrinth seals are independently controllable by the rotary body and the stationary parts of the labyrinth seals bearing parts of the housing independently and / or are formed axially displaceable relative to each other. In this way, even with multi-stage turbine arrangements, the sealing gaps of the respective individual areas can be set individually, which is particularly expedient if different temperatures are applied to different areas of the turbine and thus the thermal expansions differ from each other.

Because the position of the shaft relative to the surrounding housing can be adjusted, the labyrinth seals existing between these elements can be adjusted to the desired gap width. The gap width of the seals between the shaft and arranged on the movable housing parts parts of the labyrinth seals can then be adjusted by moving these housing parts.

Because in addition to the axial position sensor more Sensors are provided between the sliding housing parts and the axis or between the sliding housing parts and the stationary housing part, can also here measure the respective relative position and set by providing an electronic controller to a desired level.

The invention also relates to a method for reducing sealing gap losses of turbomachinery with a housing and a rotary body arranged therein with at least one labyrinth seal, which is characterized in that the rotary body is axially displaced such that the gap width of the sealing gap of the labyrinth seal in a adjustable tolerance range remains. With the method according to the invention, in small radial turbines such as in exhaust gas turbochargers, gas and steam turbines or air turbines and corresponding compressors in conjunction with outer surfaces of the wheels and the labyrinth seal webs, the sealing gap surface causing the losses can be reduced to a fraction of the losses given today.

Further features, details and advantages of the invention will become apparent from the following description and from the drawing. This shows in

1 shows a section through a working machine according to the invention in two positions,

2 shows a partial section through an axial turbine according to the invention in two positions,

3 shows a section through a radial turbine according to the invention in two positions, 4 shows a section through a part of a turbomachine according to the invention in two positions and in FIG

5 shows a partial section through a turbomachine according to the invention in two positions.

A turbomachine according to the invention generally designated by 100 is shown in more detail in FIG. It has two turbine stages 102 and 103 and two compressor stages 104 and 105, which are all mounted on a common rotary body 106 and rotatably arranged in a machine housing 101.

The rotary body 106 is floatingly supported by an electromagnetic thrust bearing 107 and other electromagnetic bearings, not shown. By means of the electromagnetic thrust bearing 107, the rotational body 106 can be displaced in the axial direction, as shown schematically. Through the entire electromagnetic bearing, the position of the rotating body 106 can be adjusted both in the axial and in the radial direction. To determine the current position of the rotary body 106, an axial position sensor 108 in the form of an inductive sensor and other non-contact position sensors are provided, which are also not shown in detail. With the measured position data of the rotating body 106, their position is accurately set even at high speeds and it is an imbalance compensation possible.

In order to minimize the secondary flow losses of the engine 100, each of the compressor and compressor stages 102, 103, 104, 105 between the rotating member 106 connected to the rotating member and the stationary housing member 101 are generally designated 110 Labyrinth seals provided. They have on the housing 101 comb-like arranged sealing blades 111. The compressor and compressor stages 102, 103, 104, 105 have corresponding sealing surfaces 112 on the edge side.

In order to keep the sealing gap losses of the seals 110 as small as possible, the axis is displaced by means of the electromagnetic thrust bearing 107 so that the distance between the turbine wheels 102, 103 and the housing 101 is smaller until it has been reduced in design to 0.005 mm. For this purpose, the position of the rotational body 106 detected by means of the axial sensor 108 is constantly compared with the value to be set and readjusted accordingly. This condition is shown in the lower part of FIG.

In order to also be able to minimize the sealing gap losses of the compressor stages 104 and 105, parts of the housing part 109 surrounding the rotary body 106 are designed to be displaceable relative to the main housing 101 and to the rotary body 106. The position relative to the rotation body 106 is determined by an inductive sensor designated 13. By a drive unit, not shown, the housing part 109 can be moved axially.

In order to reduce the sealing gap losses of the compressor stage, the latter is displaced in the axial direction depending on the measured position data of the housing part 110 until the gap between the sealing surfaces 112 of the compressor wheels 104, 105 and the stationary laminations 111 of the labyrinth seals 110 has reached the desired value. In this way, thermal expansions of the rotational body 106 and the housing parts 101, 109 are compensated even with rapid change of the thermal loads, without the efficiency of the machine due to the sealing gap Losses decreases or mechanical contact and thus destruction of fast-rotating can occur with the fixed housing parts.

The embodiment partially shown in FIG. 2 of an axial turbine 200 according to the invention has an axially arranged labyrinth seal 210 between the rotary body 206 and the housing part 201. In this case, the housing 201 has an axially displaceable, substantially cylindrical cover part 221, which is connected by a movable, circumferential membrane 222 tightly connected to the housing part 201. The cover part 221 has the fixed part of the labyrinth seal 210 in the form of a plurality of comb-like protruding louvers 211. On the shaft corresponding, in this slats engaging, also comb-like circumferential lamellae 212 are arranged.

By a mechanical or electromechanical adjustment mechanism, not shown, the cylindrical cover 221 is displaced relative to the rotation body 206, so that the gap 213 between the stationary lamellae 211 of the labyrinth seal and the rotating lamellae 212 is reduced, as shown in part "b)" of FIG. 2 shown.

In the embodiment of a device 300 according to the invention shown in FIG. 3, a radial turbine or compressor wheel 306a is arranged in a stationary housing part 301. At the end faces of the radial wheel 306a there are labyrinth seals 310, which likewise consist of a fixed part 311 arranged on the housing 301 and a rotating part 312 arranged on the radial wheel 306a. The inventive axial displacement of the rotary body 306, the Radialturbinen- or compressor 306a can be moved in the direction of the fixed housing 301, as in the area "b)" of the drawing shown. As a result, the gap distance of the labyrinth seal 310 can be adjusted as already described.

In the embodiment of the invention shown in Fig. 4, the labyrinth seal 410 is located on a lateral surface between a housing part 401 and the rotary body 406. The lateral surface is located on a circular segment around the center of mass of the rotary body 406. Again, can, as shown, by a displacement of the shaft in the axial direction of the distance between the fixed parts 411 of the plate seal 410 and the rotating parts 412 of the lamellar seal 410 to reduce the gap losses are reduced to a desired level.

By arranging on a circle segment around the center of gravity of the rotating body 406, this completes a precession movement with a complete electromagnetic bearing around its center of mass.

In the embodiment of the invention with a two-stage turbine 500 shown in FIG. 5, labyrinth seals 510 are provided between the two turbine wheels 506a and 506b as well as the corresponding peripheral surfaces 511a and 511b. These consist of comb-like, circumferential lamellae 512 on the outer edge surfaces of the turbine wheels and corresponding thereto lateral surfaces 511 in the fixed housing 501 of the turbine. Again, by axial displacement of the rotary body 506 supporting the turbine wheels 506a and 506b, the gap between the fins 512 and the corresponding lateral surface 511 is set to the desired level as shown in the lower portion of FIG.

Of course, the invention is not limited to those described Embodiments limited, but changeable in many ways without departing from the spirit. Thus, in addition to the illustrated simple displaceability of the rotary body and the additional displaceability of a housing part and a structure with even more movable parts and corresponding adjustable seals of the overall system is possible, as well as the exact design and position of the labyrinth seals can be made at all technically meaningful points of the turbine, As shown by the different examples, as well as the type of work machine parts, ie turbine stages, compressor stages, radial or axial guidance of the flow media. Embodiments as high, medium or low pressure systems are possible, provided that the principle of the invention expressed in the claims is maintained.

Claims

Claims:

1. A device for reducing sealing gap losses of turbomachinery with a housing (101,201,301,401,501) and a rotational body arranged therein (106,206,306,406, 506), wherein between the housing (101,201,301,401,501) and rotary body (106,206,306,406,506) at least one labyrinth seal (110,210,310,410,510) is arranged, characterized in that the rotational body (106,206,306,406,506) and / or the housing part (120) carrying a fixed part (111,211,311,411,511) of the at least one labyrinth seal (110,210,310,410,510) is axially displaceable so that displacement of the rotational body (106,206,306, 406,506) and / or the housing part (120 ) the gap width of the at least one labyrinth seal (110, 210, 310, 410, 510) is adjustable.

2. Apparatus according to claim 1, characterized in that at least one sensor element (108,113) for determining at least the axial position of the rotary body (106) and / or the displaceable housing part (120) is provided.

3. Apparatus according to claim 1 or 2, characterized in that at least one electronic control arrangement for the axial positioning of the rotary body (106,206,306,406, 506) and / or the displaceable housing part (120) is provided depending on the measured sensor information.

4. Device according to one of the preceding claims, characterized the rotational body (106, 206, 306, 406, 506) is mounted electromagnetically and / or is designed to be electromagnetically axially displaceable.

5. Device according to one of the preceding claims, characterized in that the labyrinth seal (210) in conjunction with an axial positioning of the shaft (206) or the housing in an axial turbine (200) or an axial compressor is used.

6. Device according to one of claims 1 to 4, characterized in that the labyrinth seal (310) in a radial turbine (300) or a radial compressor in conjunction with an axial positioning of the shaft (306) or the housing is used.

7. Device according to one of claims 1 to 4, characterized in that the labyrinth seal is used in conjunction with an axial positioning of the shaft or the housing in a diagonal turbine or a diagonal compressor.

8. Device according to one of the preceding claims, characterized in that the labyrinth seal (410) on two axisymmetric circular segment-shaped surfaces around the center of gravity of the rotary body (406) is provided and the labyrinth seal (410) respectively on the housing part (401) and the rotary body (406 ) spaced apart labyrinth webs (411,412), wherein the distance of the labyrinth webs (411,412) is dimensioned such that the working shaft can perform a free Präzessionsbewegung.

9. Apparatus according to claim 2 or one of the following, characterized in that the sensors (108) are designed as non-contact sensors.

10. Device according to one of the preceding claims, characterized in that the rotational body (106,206,306,406,506) is movable to a sealing gap width between 0.1 and 0.005 mm.

11. Device according to one of the preceding claims, characterized in that the rotary body (206) at least partially surrounding housing cover (221) is provided, on which a fixed part (211) of the labyrinth seal (210) is arranged and with a pressure-resistant membrane (222) connected to the housing (201) and formed mechanically or electromechanically axially movable.

12. Device according to one of the preceding claims, characterized in that the rotary body (106,206,306,406,506) partially carries turbine blades, which have an outer circumferential surface formed as part of an upper and / or lower radial labyrinth seal (110,210,310,410,510).

13. Device according to one of the preceding claims, characterized in that in the presence of more than one labyrinth seal (110) between the rotary body (106) and the housing (101,120) the sealing gaps of the individual labyrinth seals (110) are independently controllable by the Rotating body (106) and the parts of the housing (101, 120) which support the stationary parts (111) of the labyrinth seals are formed independently of each other and / or axially displaceable relative to each other.

14. A method for reducing sealing gap losses of turbomachinery comprising a housing (101, 201, 301, 401, 501) and a rotational body (106, 206, 306, 466, 506) arranged therein with at least one labyrinth seal (110, 210, 310, 410, 510) having a device according to claim 1 or one of the following claims, characterized in that the rotational body (106,206,306,406,506) is axially displaced such that the gap width of the sealing gap of the labyrinth seal (110) remains within an adjustable tolerance range.