WO2010112509A2

WO2010112509A2 - Rotor for a turbomachine

Info

Publication number: WO2010112509A2
Application number: PCT/EP2010/054210
Authority: WO
Inventors: Wolfgang Zacharias
Original assignee: Siemens Aktiengesellschaft
Priority date: 2009-04-01
Filing date: 2010-03-30
Publication date: 2010-10-07
Also published as: WO2010112509A3; RU2482336C1; EP2414637A2; BRPI1009988A2; RU2011144023A; CN102449267A; US20120014790A1

Abstract

The invention relates to a rotor (2) for a turbomachine, comprising a shaft (6) and a longitudinal bearing disk (8) arranged thereon as an element for an axial bearing for axially supporting the shaft (6). It is proposed that the longitudinal bearing disk (8) comprise a first, cylindrical contact surface (14) for radial support on the shaft (6) and a second, conical contact surface (22) for self-centering on the shaft (6). A rotor for a turbomachine can be achieved that is designed for operation with chemically aggressive gases and can be operated at high rotational speeds in a range of over 10,000 rpm.

Description

description

Rotor for a turbomachine

The invention relates to a rotor for a turbomachine with a shaft and arranged thereon

Longitudinal bearing disc as an element for a thrust bearing for axial bearing of the shaft.

On a shaft of a turbomachine, such as a gas or steam turbine or a turbocompressor, working members are arranged, for example, in the form of paddle wheels, by which a stationary pressure difference between an inlet and outlet of the turbomachine is built up or broken down. Through the operation of the working organs is a high force in

Axial direction of the shaft transmitted to the shaft, which is absorbed by a thrust bearing. The thrust bearing comprises a longitudinal bearing disc, which is part of the rotor, and bearing elements on the stator, on which the longitudinal bearing disc - supported by magnetic forces or by oil-guided sliding - depending on the type of bearing.

In industrial turbomachines, especially those used in the chemical industry, sometimes speeds in the range of several 10,000 revolutions per minute are required. Such high speeds require enormous strength of both the work organs and the longitudinal bearing disc, which has a relatively large radius for receiving and passing a high axial thrust and is therefore exposed to high centrifugal forces. In order to ensure the required high strength, high-alloy steels with a yield strength around 1000 N / mm ² are usually used.

If a turbomachine, in particular in the industrial sector, is in contact with aggressive gases, for example when compressing gases containing hydrogen sulphide, the working elements and also the longitudinal bearing disk become chemically attacked, so that their strength is impaired. However, steels that are not corroded by hydrogen sulphide have a maximum strength of only 700 N / mm ² . Thus, turbomachines that communicate with hydrogen sulphide or similar aggressive gases can only be operated at lower speeds than machines that are not designed to handle such aggressive chemical gases.

It is an object of the present invention to provide a rotor for a turbomachine, which can be designed both for operation with chemically aggressive gases and at high speeds in the range of over 10,000 rev / min.

This object is achieved by a rotor of the type mentioned, in which the longitudinal bearing disc according to the invention has a first, cylindrical contact surface for radial mounting on the shaft and a second, conical contact surface for self-centering on the shaft.

The invention is based on the consideration that longitudinal bearing discs are mounted in the known embodiment by means of a hydraulic shrinkage bandage on the shaft of the rotor. Here, the longitudinal bearing plate is hydraulically expanded and pushed onto a slightly conical contact surface of the shaft against a stop. A shaft nut holds the shrunk longitudinal bearing disc axially in position. So that the longitudinal bearing disc does not slip on the contact surface of the shaft, it must also be strong

Centrifugal forces still be able to maintain their stable interference fit on the contact surface, which requires that the interference fit must be very firm. As a result, the steel of the longitudinal bearing plate is very heavily stressed.

If a stable connection is achieved even without a shrink fit, so eliminates the forces acting on the shrinkage forces on the longitudinal bearing disc and this can their entire Use strength to hold the centrifugal forces. By reducing the stresses occurring by eliminating the stresses from the shrink fit suitable materials for the longitudinal bearing disc can be used for compressing hydrogen sulfide even at high speeds.

By the first, cylindrical contact surface, the longitudinal bearing disc can be held radially in position and thus an imbalance can be avoided. The second, conical

The contact surface serves to transmit the tangential forces from the longitudinal bearing disk to the shaft so that it does not rotate relative to the shaft. For transmitting the forces, the longitudinal bearing disk is expediently pressed by a shaft nut with its conical contact surface against a counter surface of the shaft or of a component fastened to it.

The turbomachine is advantageously a turbomachine, in particular a turbocompressor. The invention is particularly advantageous to such

Longitudinal washer applicable, which is part of a magnetic bearing. Due to the magnetic bearing, the longitudinal bearing disk is made relatively large and thus heavily loaded mechanically at high revolutions. Due to the magnetic bearing a particularly low-friction storage can be achieved.

The conical contact surface serves to self-center the longitudinal bearing disc on the shaft. Conveniently, the conical bearing surface does not directly adjoin the first, cylindrical abutment surface, in order to avoid a sharp edge which causes the shaft to slip when pushed on

Longitudinal bearing washer could injure the shaft. Therefore, the two contact surfaces are expediently spaced from each other, for example by a flat intermediate surface, such as a chamfer, or may be connected by a rounding.

In an advantageous embodiment of the invention is the second contact surface rebound conical to the radial compression of the longitudinal bearing disc. As a result, widening of the longitudinal bearing disk is avoided with compressed contact surfaces, so that the longitudinal bearing plate is mechanically protected. The compression affects the

Against centrifugal forces and thus has an advantageous effect on the strength of the longitudinal bearing disc.

For simultaneous transmission of tangential forces, the conical bearing surface and its counter surface can be designed as a Hirth connection. However, this embodiment has the disadvantage that it is associated with a high production cost. It is therefore a conical shape in the form of a frustoconical surface is preferred in which a force transmission from the contact surface to the mating surface by a frictional connection, ie by static friction. The force with which the longitudinal bearing disc is pressed at its conical contact surface against the counter surface is chosen to be so large that the resulting force on the contact surface by friction moments can transmit the necessary starting moments without sliding the second contact surface on its counter surface.

Advantageously, the second contact surface with an angle of inclination to the radial direction of the shaft between 5 ° and

30 ° executed. The greater the angle of inclination, the higher the friction torque between - with the same preload force

Contact surface and counter surface, but also associated with a higher mechanical stress on the longitudinal bearing disc and the shaft. By optimizing the

Inclination angle, the forces occurring can be adjusted to the particular case of need.

Conveniently, the longitudinal bearing disc is mounted so that with increasing speed an increasing bearing force acts on the second bearing surface. This can be achieved in particular by the recessed conicity of the second contact surface. With increasing speed leads the increasing Radial force to an increasing contact pressure of the second contact surface against its counter surface, whereby the transmittable torque is increased, which is generated by friction effect of the two contact surfaces together.

Advantageously, a temperature increase of the longitudinal bearing disc leads to an increasing bearing force of the second contact surface. A decrease in frictional forces on the contact surfaces can be counteracted thereby.

Moreover, it is advantageous if the longitudinal bearing disc is mounted stress-free on the shaft with the first contact surface. The longitudinal bearing disc can be mechanically protected and thus driven at high speeds. A lack of tension is given if the longitudinal bearing disc can be pushed by hand onto the shaft for supporting the first contact surface on its corresponding counter surface.

A safe installation of the longitudinal bearing disc and safe operation of the rotor can be achieved when the second

Abutment surface abuts a conical counter surface, which is incorporated in the shaft. The conical counter surface is thus directly part of the shaft, so that a wave ring or a similar component can be omitted.

Advantageously, the second contact surface is an end face of the bearing disk, wherein an end face is understood to mean a surface having an inclination of less than 45 ° to the radial direction of the shaft.

In order to avoid an imbalance of the longitudinal bearing disc after disassembly and reassembly, an anti-rotation lock is expediently provided which predetermines a fixed tangential position of the longitudinal bearing disc on the shaft. The anti-rotation can also during the

Operating tangential forces, which is generated for example when starting the rotor or by friction of the longitudinal bearing disc in the camp record. However, it makes sense that the Anti-rotation is made as small as possible in order not to affect the stability of the longitudinal bearing disc too strong. It is therefore advantageous if the second contact surface is provided for transmitting at least the major part of the tangential forces from the shaft to the longitudinal bearing disk. The vast majority is more than 50% of the tangential forces.

In a further advantageous embodiment of the invention, the rotor is equipped with an anti-rotation device, which holds the longitudinal bearing disc by a positive connection in a tangential target position. A change of balancing states after disassembly and reassembly can be avoided.

The positive connection can be made directly between the longitudinal bearing disc and shaft, for example by a tongue and groove connection in or near the first contact surface. By a recess of a radially inwardly facing surface of the longitudinal bearing disc, however, the longitudinal bearing disc is not significantly affected in their strength. It is therefore advantageous if a positive locking element of the anti-rotation device engages in an end face of the longitudinal bearing disk. A recess in the end face leads to a significantly lower mechanical stress on the foot of the

Longitudinal bearing disc at high revolutions. Conveniently, the end face is arranged opposite the second contact surface. The second contact surface can be designed to be free from interferences and entirely based on friction transmission.

Advantageously, the anti-rotation comprises an anti-rotation ring, which at least indirectly has a positive connection with the longitudinal bearing disc and in the same direction at least indirectly has a positive connection with the shaft. A positive power transmission from the longitudinal bearing disc on the anti-rotation ring can be continued in a simple manner in the same direction, for example in the tangential direction to the shaft. A Production of the elements can be kept simple, if the two form-fitting are each formed by a positive locking element which engages in the form-fitting connected elements. The positive connection between the anti-rotation ring and the shaft is suitably achieved by a feather key which engages in a groove of the anti-rotation ring and the shaft. For reasons of force two positive locking elements are expediently provided for each of the two form-fitting.

The feather key and the interlocking element are expediently arranged tangentially offset from each other, with two interlocking elements and two feather keys, which are advantageously mounted opposite each other, interlocking elements and feather keys are advantageously arranged at an angle of 90 ° to each other.

With a strong increase in temperature, it may be that the longitudinal bearing plate expands particularly strong in the axial direction. Under certain circumstances, the second contact surface presses against its counter surface with an undesirably high force, so that a high mechanical load is created as a result. To mitigate this stress, the rotor expediently comprises a spring means for cushioning bearing forces on the second contact surface. The spring means may receive its spring action through a recess which is compressed in a resilient movement. The recess may be on the longitudinal bearing disk or in the component that the mating surface forms the conical contact surface of the longitudinal bearing disk, in particular directly in the shaft.

The invention will be explained in more detail with reference to an embodiment which is shown in a drawing. Their single FIGURE shows a section of a section of a rotor 2 of a turbomachine in the form of a

Axial compressor. The rotor 2 comprises a shaft 6 extending in the axial direction 4, on which a longitudinal bearing disc 8 is mounted. The longitudinal bearing disc 8 is part of a Axial bearings 10, of which two magnetic poles 12 are schematically indicated for better understanding, which support the longitudinal bearing disc 8 in the axial direction 4. The thrust bearing 10 is thus a magnetic bearing for holding the shaft 6 in an intended axial position.

The longitudinal bearing disc 8 is provided with a first, hollow-cylindrical bearing surface 14 which rests on a likewise cylindrical counter-surface 16 of the shaft 6. The bearing formed by the contact surface 14 and the mating surface 16 holds the longitudinal bearing disk in the radial direction 18 without play on the shaft 6. The longitudinal bearing disk 8 has a first end face 20 and a second end face opposite it, which is designed as a second and conical contact surface 22. The contact surface 22 abuts against a counter surface 24, which is incorporated directly into the material of the shaft 6.

The contact surface 22 is provided with an inclination angle α of 25 °, wherein the contact surface 22 is designed to spring back, so that the counter surface 24, the longitudinal support disk i in the region of the contact surface 22 a piece far overlaps. As a result, the longitudinal bearing disc 8 is compressed in an axial bracing of the longitudinal bearing disc 8 and pressed against a centrifugal force on the shaft 8. Due to the conicity of the contact surface 22, a self-centering of the longitudinal bearing disc 8 is effected on the shaft 6, which supports the centering of the longitudinal bearing disc 8 by the systems of the surfaces 14, 16.

In order to avoid abutting an edge of the longitudinal bearing disc 8 on the shaft material, a chamfer 26 is incorporated between the two contact surfaces 14, 22, wherein a rounding between the contact surfaces 14, 22 is useful. A cavity 28 in the shaft material leads to a

Reduction of load peaks in the material of the shaft 6 at a high contact pressure of the longitudinal bearing disc 8 in the axial direction 4 against the shaft 6. For the same purpose Hollows 30 introduced on both sides in the longitudinal bearing disc 8, wherein the cavities 28, 30 are advantageously carried out by calculation by the finite element method to effect on the wall along the cavities 28, 30 as uniform as possible material tension.

A shaft nut 32, which is positively connected by a thread 34 with the shaft 6, is braced for mounting the longitudinal bearing disc 8 against a Verdrehsicherungsring 36 which presses the longitudinal bearing disc with its contact surface 22 against the corresponding counter surface 24. A biasing force F _v applied by the shaft nut 32 is chosen to be so large that the normal force F _N resulting from an axial force F _AX and the inclination angle α

Contact surface 22 on the counter surface 24 such a high friction effect achieved that the longitudinal bearing disc 8 does not slip on a start of the rotor 2 on the shaft 6 in the tangential direction.

As the speed increases, the increasing radial force F _{R leads to} an even larger normal force F _N. This automatically increases the transmittable moment, which is generated by the friction effect of the longitudinal bearing disk 8 on the counter surface 24. Also a temperature increase in the

Longitudinal bearing disc 8 generated by the expansion of the longitudinal bearing disc 8 in the axial direction 4, a higher normal force F _N and thus a higher transmissible torque. The resulting axial force F _AX is absorbed by the shaft nut 32.

In order to avoid an excessive normal force F _N or axial force F _M at a very high temperature of the longitudinal bearing disk 8 and thus material damage to the longitudinal bearing disk 8 or shaft 6, a recess 38 is inserted into the shaft 8. The recess surrounds the shaft 6 all around and thus forms a slightly elastic web 40, the pressure of the two contact surfaces 22, 24 to each other on a limited material harmless size.

A mounting or dismounting of the longitudinal bearing disc 8 can be done in a simple manner by the longitudinal bearing disc 8 is pushed by hand on the shaft 6 or withdrawn from this. In order to avoid an imbalance after disassembly, the longitudinal bearing disc 8 should sit again in its original tangential position on the shaft 6 in a new assembly. To ensure this, between the shaft nut 32 and the longitudinal bearing disc 8 of

Anti-rotation ring 36 is arranged, which has two positive locking elements 42 in the form of bolts in

Tangential, ie circumferential direction, positively connected to longitudinal bearing disc 8 is connected.

The form-fit elements 42, of which only one is shown for the sake of clarity, the other is offset from the rotation axis 44 of the shaft 6, so they engage in the end face 20 of the longitudinal bearing disk 8, so that the contact surface 14 of the longitudinal bearing disk 8 unimpaired. Both the anti-rotation ring 36 and the shaft 6 are provided with a groove 46 and 48, respectively, held in position tangentially to each other via a key 50 made of a rectangular steel. In this way, between the shaft 6 and the longitudinal bearing disc 8 an indirect positive connection is made such that the longitudinal bearing disc 8 is mounted in the tangential direction only in a preset position and remains in this position.

Also, the feather key 50 is provided in a double version, wherein both feather keys 50 are also arranged with respect to the axis of rotation 44 opposite. The feather keys 50 are offset from the interlocking elements 42 in the tangential direction 90 °. They are merely drawn to simplify the figures in the same sectional plane in order to dispense with a further sectional view through the rotor 2 rotated by 90 ° about the rotation axis 44 can. The interlocking element 42 and the feather key 50 can be designed as an additional safeguard against a tangential rotation of the longitudinal bearing disk 8 on the shaft 6. To keep the stability and thus the dimensions of these two elements low, the interaction of bias F _v , contact surface 22nd and inclination angle α selected so that slipping of the longitudinal bearing disc 8 on the shaft 6 in the tangential direction would not take place even without these two elements. They serve therefore mainly the

Mounting aid and as a backup for receiving tangential forces in case of undesirable or unforeseen conditions.

Claims

claims

1. rotor (2) for a turbomachine with a shaft (6) and arranged thereon a longitudinal bearing disc (8) as

Element for a thrust bearing for the axial bearing of the shaft (6), characterized in that the longitudinal bearing disc (8) has a first, cylindrical contact surface (14) for radial support on the shaft (6) and a second, conical contact surface (22) for self-centering on the shaft (6).

2. rotor (2) according to claim 1, characterized in that the second contact surface (22) is recessed conically to the radial compression of the longitudinal bearing disc (8).

3. rotor (2) according to claim 1 or 2, characterized in that the second contact surface (22) has an inclination angle to the radial direction (18) of the shaft (6) between 5 ° and 30 °.

4. rotor (2) according to any one of the preceding claims, characterized in that the longitudinal bearing disc (8) is mounted so that with increasing speed an increasing bearing force acts on the second bearing surface (22).

5. rotor (2) according to any one of the preceding claims, characterized in that the longitudinal bearing disc (8) with the first contact surface (14) is mounted stress-free on the shaft (6).

6. rotor (2) according to any one of the preceding claims, characterized in that the second bearing surface (22) on a conical mating surface (24) abuts, which is incorporated in the shaft (6).

7. rotor (2) according to any one of the preceding claims, characterized in that the second bearing surface (22) is an end face of the longitudinal bearing disc (8).

8. rotor (2) according to any one of the preceding claims, characterized in that the second bearing surface (22) for transmitting at least the major part of the tangential forces of the shaft (6) on the longitudinal bearing disc (8) is provided.

9. rotor (2) according to any one of the preceding claims, characterized by a rotation, which holds the longitudinal bearing disc (8) by a positive connection in a tangential target position.

10. rotor (2) according to claim 9, characterized in that a positive locking element (42) of the anti-rotation in an end face (20) of the longitudinal bearing disc (8) engages.

11. rotor (2) according to claim 9 or 10, characterized in that the end face (20) opposite the second abutment surface (22) is arranged.

12. Rotor (2) according to any one of claims 9 to 11, characterized in that the anti-rotation comprises a Verdrehsicherungsring (36), at least indirectly a form fit with the longitudinal bearing disc (8) and in the same direction at least indirectly a positive connection with the shaft (36). 6).

13. Rotor (2) according to any one of the preceding claims, characterized by a spring means for cushioning bearing forces on the second bearing surface (22).

14. rotor (2) according to claim 13, characterized in that the spring means receives its spring action by a recess (38) which is compressed in a spring.