Patent Application
20130315714
The invention relates to a method for pulling a bearing body off the rotor of a preferably stationary gas turbine having a casing which can preferably be divided into halves, while the casing is closed. The invention furthermore relates to a tubular shaft extension for parking a bearing body of a rotor of a preferably stationary gas turbine having a casing which can preferably be divided into halves.
Stationary gas turbines have long been known from the extensive prior art. The rotors thereof are generally supported radially both at a compressor end and at a turbine end. The turbine-end radial bearing of gas turbines is situated within the exhaust section of the gas turbine, generally directly after the last guide vane cascade of the turbine unit. For support, there is generally a small number of radially extending bearing struts in the exhaust section, i.e. four, five or six such struts, in the center of which a bearing housing for the bearing body of the turbine-end radial bearing is located.
Faults in the bearing body or in the bearing shells can lead to a need to replace said components. In the case of stationary gas turbines, which are generally fitted with a casing which can be divided into halves in a parting plane, the upper casing half of the stationary gas turbine must first be released from the lower casing half and then lifted off in the event of a repair. The rotor including the bearing must then be removed from the lower casing half, and only then can the bearing be pulled off the rotor.
However, this procedure is particularly time-consuming since a relatively long preparation time is required after the cooling of the gas turbine in order to release the screwed joints of the casing, open the gas turbine and remove the rotor. After the faulty component has been repaired, the rotor must be replaced in the lower casing half and aligned. The upper casing half is then fitted. After this, the casing halves have to be fastened to one another by means of the known screwed joints, and this likewise greatly increases the downtime of the stationary gas turbine.
For these reasons, there is a need to shorten the downtime of the gas turbine.
It is therefore an object of the invention to provide a method that overcomes the abovementioned disadvantages. It is a further object of the invention to provide a tool which supports the method.
The object as it is directed to the method is achieved by the following steps:
a) supporting the rotor (12) and/or
b) holding the rotor (12) in order to free the bearing body (10) of the weight of the rotor,
Further advantageous embodiments and features are given in the dependent claims.
According to the invention, provision is made for fixing a shaft extension on the relevant end of the rotor. The relevant radial bearing is then freed of the weight of the rotor by supporting the rotor from below and/or holding it from above. Through the freeing of the radial bearing from the radially acting weight-associated forces of the rotor, the latter is first of all fixed indirectly, with radial clearance, on the radial struts. The sliding elements, which are provided only for disassembly and assembly, are then fitted between the bearing body and the rotor. After this, the bearing body can be moved onto the shaft extension and parked there for the repair work to be carried out thereon. In the parked position, the bearing body is secured against any further movement. At the same time, it is accessible from all sides. The free accessibility of the bearing body then allows it to be repaired within the exhaust casing of the gas turbine without the need to open up the gas turbine for this purpose. The opening of the upper casing half of the stationary gas turbine and the removal of the rotor are eliminated completely. This significantly reduces the preparation time for the repair of the relevant bearing and thus increases the availability of the gas turbine to the same degree.
According to a first advantageous embodiment of the method, the bearing body is of undivided configuration in the circumferential direction. The integral embodiment of the bearing body is a particularly simple way of allowing the bearing body to be moved along the shaft extension. Moreover, there is no need for adjustment of any bearing body halves relative to the rotor during the installation of the bearing body that has to be carried out after the repair. Consequently, this measure too allows particularly rapid removal and installation of the bearing body.
According to a particularly preferred method, the bearing body is secured against rotation or pivoting during and after axial movement by means of an anti-rotation device. This measure increases workplace safety for the fitters carrying out the movement and repair since uncontrolled movement of the bearing body during the axial movement and then in the parked position cannot occur.
At least one guide extending in the axial direction is preferably provided as an anti-rotation device on the shaft extension, said guide limiting the tangential movement of a pin fixed rigidly on the bearing body when there is a risk of rotary motion of the bearing body. The advantage of this embodiment of an anti-rotation device lies in its suitability for simple and low-cost manufacture. For example, the guide is embodied as a U-profile, along the outward-facing web of which the pin can slide with a particularly small clearance. Thus, the two edges of the U-profile, which lie on a larger radius than the center of the web, limit the movement of the pin in the circumferential direction, reliably preventing tangential movement of the bearing body when there is a risk of such movement. Instead of the U-profile, it is, of course, also possible to use in a similar way a flat profile mounted on the outside, perpendicularly to the radius of the shaft extension. This is of flatter construction and allows the use of the method with bearing bodies that have a relatively small inside diameter as well.
It is expedient if the shaft extension is fixed on the relevant end of the rotor in such a way that it can be released again. For this purpose, provision is made for the shaft extension to be screwed onto the end of the rotor. This embodiment is advantageous particularly for rotors of a kind which are in any case embodied with a central tie rod and the end of which is in any case provided with a thread. Adaptation of rotors of this kind for carrying out the method according to the invention is not necessary.
It is a particularly simple matter to align the shaft extension before screwing it onto the rotor if the shaft extension is resting on a roller bracket which, for its part, is supported so as to allow radial and tangential movement. Accordingly, the roller bracket is positioned in such a way that the shaft extension can be screwed onto the rotor without misalignment. On conclusion of positioning, the shaft extension, which is designed as a tube, is rotated on the roller bracket and, in the process, simultaneously screwed onto the rotor. Damage to the thread forming part of the screwed joint is thereby reliably prevented.
The bearing body is preferably supported on the rotor and/or on the extension thereof at two axial positions by means of the sliding elements. This prevents tilting of the bearing body relative to the rotor or the rotor extension, ensuring that it is always concentric and coaxial with the machine axis.
According to the invention, the tubular extension for parking a bearing body of a rotor of a preferably stationary gas turbine having a casing which can preferably be divided into halves has an internal thread at one end for screwing the shaft extension onto one end of the rotor of the gas turbine and at least one guide, arranged on the outside of the shaft extension, for forming one of two mating parts of an anti-rotation device for the bearing body, which can be moved along the shaft extension.
The advantages relating to the shaft extension correspond here to the advantages of the method.
Further advantages, features and characteristics of the invention are explained in greater detail by means of a preferred illustrative embodiment in the following drawings, in which:
The rotor 12 is then supported directly on the turbine exhaust casing 11 of the gas turbine 14 at the turbine end via elements (not shown specifically), thus freeing the bearing body 10 from the weight of the rotor 12. Commercially available clamping elements of the “Superbolt” brand, in particular, are suitable for this purpose. At the same time or afterwards, sliding elements 22 or, alternatively, sliding shoes are then fitted between the bearing body 10 and the rotor 12 or shaft extension 18, thus enabling the bearing body 10 to be moved along the machine axis 24 with the aid of said sliding elements 22.
It should be noted that the bearing shells that are usually provided in the bearing body 10 are not shown in any of the figures shown here and can be removed from the bearing body 10 even before fixing the shaft extension 18 on the relevant tie rod end 20.
The bearing body 10 can then be pushed along the machine axis 24, onto the shaft extension, by axial movement—i.e. translation—and parked there (
In
The second mating part required to form the anti-rotation device 26 is illustrated in perspective in
During the implementation of the method according to the invention, the bolt 39 mounted on the pin end 29 is unscrewed from the pin 29 until its lies opposite a web center 43 of the U-profile with a particularly small clearance. The edges 41 between the flank and the web 30 of the U-profile lie on a larger radius than the web center 43 between the two edges 41. If there is a risk of tangential movement of the bearing body 10—i.e. movement in the circumferential direction—this movement is blocked since the bolt 39 strikes against the edge 41 due to the relatively small clearance between the web center 43 and said bolt. It is thereby possible reliably to avoid a rotary motion of the bearing body 10 during and after movement onto the shaft extension 18, which would endanger the fitters. At its free end 40, the shaft extension 18 furthermore has a stop 42 in the form of a plate, which serves to limit the axial travel of the bearing body 10. This reliably avoids the possibility of the bearing body 10 being pushed off the shaft extension 18.
A flat profile is also suitable as a bearing surface or guide instead of the U-profile. This is then fixed on the shaft extension 18 in such a way that the flat side thereof is aligned perpendicularly to the radius of the shaft extension and parallel to the machine axis 24. The same effect as that achieved with the U-profile is thereby obtained.
Overall, the invention relates to a method for pulling a bearing body 10 off the rotor 12 of a preferably stationary gas turbine 14 having a casing which can preferably be divided into halves, while the casing is closed. In order to reduce the assembly and disassembly time when repairing a bearing body 10 of a corresponding gas turbine 14, provision is made, according to the invention, for fixing a shaft extension 18 on the relevant end 20 of the rotor 12 and the rotor 12 is simultaneously supported and/or held in order to free the bearing body 10 of the weight of the rotor 12. Sliding elements 22 are then fitted between the bearing body 10 and the rotor 12, after which the bearing body 10 can be pushed along the machine axis 24 onto the shaft extension 18 and parked there.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011010790.8 | Feb 2011 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2012/050125 filed Jan. 5, 2012 and claims benefit thereof, the entire content of which is hereby incorporated herein by reference. The International Application claims priority to the German application No. 10 2011 010 790.8 DE filed Feb. 9, 2011, the entire contents of which is hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/050125 | 1/5/2012 | WO | 00 | 8/1/2013 |
