EP2342425B1 - Gas turbine with securing plate between blade base and disk - Google Patents

Description

The invention relates to a turbine rotor for a gas turbine with a number of each combined into blade rows, each arranged on a turbine disk blades each having a blade root, which is arranged in each case in an axially extending blade holding the turbine disk, wherein between the respective blade root and a groove bottom the blade holding groove is arranged a securing plate for securing blades against displacement along the blade holding groove, which is fixed by means of folds on the turbine disk.

Gas turbines are used in many areas to drive generators or work machines. In this case, the energy content of a fuel is used to generate a rotational movement of a turbine rotor. For this purpose, the fuel is burned in a combustion chamber, compressed air being supplied by an air compressor. The working medium produced in the combustion chamber by the combustion of the fuel, under high pressure and at high temperature, is guided via a turbine unit arranged downstream of the combustion chamber, where it relaxes to perform work.

To generate the rotational movement of the turbine rotor, a number of rotor blades, which are usually combined into blade groups or blade rows, are arranged thereon. In this case, a turbine disk is usually provided for each turbine stage, to which the blades are fastened by means of their blade root. For guiding the flow of the working medium in the turbine unit also commonly associated between adjacent blade rows with the turbine housing and combined into rows of guide vanes are arranged.

The combustion chamber of the gas turbine may be embodied as a so-called annular combustion chamber, in which a plurality of circumferentially arranged around the turbine rotor burners in a common, surrounded by a high temperature resistant surrounding wall combustion chamber space opens. For this purpose, the combustion chamber is designed in its entirety as an annular structure. In addition to a single combustion chamber can also be provided a plurality of combustion chambers.

Immediately adjoining the combustion chamber is generally followed by a first row of guide vanes of a turbine unit which, together with the blade row immediately downstream in the flow direction of the working medium, forms a first turbine stage of the turbine unit, which is usually followed by further turbine stages.

In the design of such gas turbines in addition to the achievable power usually a particularly high efficiency is a design target. An increase in the efficiency can be achieved for thermodynamic reasons basically by increasing the outlet temperature, with the working medium from the combustion chamber off and flows into the turbine unit. Temperatures of about 1200 ° C to 1500 ° C for such gas turbines are sought and achieved.

At such high temperatures of the working medium, however, exposed to this components and components are exposed to high thermal loads. In order to protect the turbine disk and the turbine rotor from the penetration of hot working fluid, sealing plates are usually provided on the turbine disks, which are mounted circularly circumferentially on the turbine disk on the respective surfaces normal to the turbine axis. In this case, a sealing plate is usually provided per turbine blade on each side of the turbine disk. These overlap in a scale-like manner and usually have a sealing wing, which extends in such a way to the respective adjacent vane, that penetration of hot working medium in the direction of the turbine rotor is avoided.

However, the sealing plates fulfill even more functions. On the one hand they form the axial fixation of the turbine blades by appropriate fasteners, on the other hand they not only seal the turbine disk against penetration of hot gas from the outside, but also avoid leakage of guided inside the turbine disk cooling air, which usually forwarded to the cooling of the turbine blades in selbige becomes.

However, the above-mentioned embodiment of the turbine disks with segmented imbricated overlapping sealing plates is relatively complicated. It is a relatively large number of sealing plates required, resulting in a relatively high design effort of the turbine disks and thus the entire gas turbine. Furthermore, a possibly required repair in the area of the turbine disks can be comparatively complicated by this construction.

An input called turbine rotor is in each case from EP 1 703 078 A1 . DE 199 25 774 A1 . GB 643,914 and DE 100 31 116 A1 known. Furthermore, from the US 4,470,757 It is known to adjust the amount of cooling air flowing into a blade by means of sheets provided therefor alone.

In addition, from the US 2008/0253895 A1 discloses a backup for blades of a gas turbine, which prevents axial displacement of the blades along their retaining grooves. The fuse comprises per blade a wave-shaped rod which is placed between the blade root bottom and groove bottom and extending beyond the length of the groove. The one ends of the rods are welded to a ring which rests on the front side of the rotor disc and blocks the displacement of the blade in one direction. On the other end face of the rotor disk, a ring is also applied, the displacement in the opposite direction blocked. Through this extend the other ends of the rods. In addition, these ends are bent, whereby the second ring is held securely. Elaborate here is the simultaneous assembly of all rods radially within the hitherto unsecured blades.

The invention is therefore based on the object of specifying a turbine rotor for a gas turbine, which, used in a gas turbine, while maintaining the greatest possible operational safety and maximum gas turbine efficiency allows a simplified design.

This object is achieved by providing a cooling air supply duct opens in the groove bottom of the blade holding grooves for coolant supply, the respective backup plate a number of cooling air holes for Having passage of coolant and the respective blade root comprises two of them with respect to the turbine axis substantially azimuthally extending grooves and in which the respective locking plate comprises two springs which are arranged such that they are positively connected to seal with the grooves of the blade root.

The invention is based on the consideration that a simplified construction of the gas turbine, in particular in the area of the turbine disks, would be possible if the hitherto customary construction could be simplified with scale-like sealing plates. A particularly simple embodiment would be possible in particular if the sealing plates could be completely eliminated. The problem here, however, is the resulting lack of fixation of the turbine blades in the axial direction. If the sealing plates are omitted, axial fixing of the turbine blades should therefore take place in a different manner. For this purpose, a securing plate is arranged between the respective blade root and the turbine rotor, which enables a particularly simple fixation of the blade root on the turbine disk and can be adapted flexibly to the respective geometric requirements of the fixing.

For fixing to the turbine disk, the respective securing plate comprises a number of bends. These include the turbine disk in the axial direction and thus enable a secure fixation. A fixation by folds is also particularly easy to manufacture by the not yet folded, flat locking plate is first fixed to the blade root of the turbine screw, the blade root is inserted with the backup plate and then the backup plate is folded for axial fixation. As a result, a particularly simple installation is possible in addition to secure fixation.

In order to guarantee a secure axial connection of the blade root with the locking plate, includes the respective Blade root first a number of in relation to the turbine rotor substantially azimuthally extending grooves and further the respective locking plate a number of springs which are arranged such that they are positively connected to the grooves of the blade root. The grooves thus serve as a receptacle for corresponding springs on the backup plate. For a secure axial connection of the locking plate is achieved with the blade root by a positive tongue and groove connection.

In addition, the respective backup plate comprises a number of cooling air holes. As a result, cooling air can be introduced through the interior of the turbine disk and through the corresponding cooling air holes in the securing plate into the blade root and thus into the turbine blade, thus enabling reliable cooling of the turbine blade.

Due to the blade to be cooled, it can be supplied with cooling air via a cooling air supply channel opening into the groove bottom of the retaining groove. In order to ensure a low-loss as possible transition of cooling air from the cooling air supply duct in the blade, the tongue and groove connection of blade root and locking plate on the one hand and the seat of the locking plate between the blade root underside and groove bottom on the other hand also designed as a seal.

However, the previously used sealing plates are not only the axial fixation of the blades, but also seal the blade root against hot gas, which could penetrate from the interior towards the turbine rotor and could cause damage there. In order to achieve a sufficient sealing of the turbine disks and the turbine rotor against ingress of hot working medium despite a loss of the sealing plates, a corresponding seal should be realized by other components. In order to achieve the desired simplification of the design, no new components should be added, but The sealing function should be realized by existing components by appropriate modifications. For this purpose, sealing wings, which each extend to the adjacent guide blade rows, should be fastened to the blade roots of the rotor blades.

Advantageously, the respective sealing wing extends with respect to the turbine rotor substantially in the axial and azimuthal direction. Thus, the sealing takes place in a plane perpendicular to the potential penetration direction of the hot working medium. As a result, complete sealing of the region lying below the blade root in the direction of the turbine rotor is achieved against hot gas flowing inside the gas turbine.

In a further advantageous embodiment, the respective blade root in each case has a sealing wing in both axial directions. This makes it possible to achieve a seal against penetrating hot gas on both sides of the turbine blade.

Advantageously, such a gas turbine is used in a gas and steam turbine plant.

The advantages associated with the invention are in particular that can be eliminated by the introduction of locking plates between the blade root and turbine disk of a gas turbine, the previously customary sealing plates, so that a much simplified and cheaper construction of the gas turbine is possible. The design of the entire blade row is thereby considerably simplified, in addition, the weight can be reduced so that fewer mechanical loads occur and the turbine disk can be made correspondingly smaller and cheaper. Furthermore, the previously required complex grooves for fixing the sealing plate in the turbine disk can be omitted. By fixing the blade root on the turbine disk by means of a tongue and groove connection is also without sealing plates a ensures particularly secure axial fixation, so that the wear during operation can be kept comparatively low.

FIG 1

einen Halbschnitt durch eine Gasturbine,

FIG 2

einen Halbschnitt durch den äußeren Umfang einer Turbinenscheibe für die Gasturbine mit Dichtplatten,

FIG 3

einen Halbschnitt durch den äußeren Umfang einer Turbinenscheibe für die Gasturbine ohne Dichtplatten, und

FIG 4

eine vergrößerte Darstellung einer Sicherungsplatte.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

a half-section through a gas turbine,

FIG. 2

a half section through the outer periphery of a turbine disk for the gas turbine with sealing plates,

FIG. 3

a half-section through the outer periphery of a turbine disk for the gas turbine without sealing plates, and

FIG. 4

an enlarged view of a locking plate.

Identical parts are provided with the same reference numerals in all figures.

The gas turbine 1 according to FIG. 1 has a compressor 2 for combustion air, a combustion chamber 4 and a turbine unit 6 for driving the compressor 2 and a generator, not shown, or a working machine. For this purpose, the turbine unit 6 and the compressor 2 are arranged on a common, also called turbine rotor turbine rotor 8, with which the generator or the working machine is connected, and which is rotatably mounted about its central axis 9. The running in the manner of an annular combustion chamber 4 is equipped with a number of burners 10 for the combustion of a liquid or gaseous fuel.

The turbine unit 6 has a number of rotatable blades 12 connected to the turbine rotor 8. The blades 12 are arranged in a ring shape on the turbine rotor 8 and thus form a number of blade rows. Furthermore, the turbine unit 6 comprises a number of stationary vanes 14, which are also attached in a donut-like manner to a vane support 16 of the turbine unit 6 to form rows of vanes. The blades 12 serve to drive the turbine rotor 8 by momentum transfer from the turbine unit 6 flowing through the working medium M. The vanes 14, however, serve to guide the flow of the working medium M between two seen in the flow direction of the working medium M consecutive blade rows or blade rings. A successive pair of a ring of vanes 14 or a row of vanes and a ring of blades 12 or a blade row is also referred to as a turbine stage.

Each vane 14 has a platform 18 which is arranged to fix the respective vane 14 to a vane support 16 of the turbine unit 6 as a wall element. The platform 18 is a thermally comparatively heavily loaded component which forms the outer boundary of a hot gas channel for the working medium M flowing through the turbine unit 6. Each blade 12 is attached to the turbine rotor 8 in a similar manner via a platform 19.

Between the spaced-apart platforms 18 of the guide vanes 14 of two adjacent rows of guide vanes, a guide ring 21 is arranged on a guide blade carrier 16 of the turbine unit 6. The outer surface of each guide ring 21 is also exposed to the hot, the turbine unit 6 flowing through the working medium M and spaced in the radial direction from the outer end of the opposite blades 12 through a gap. The guide rings 21 arranged between adjacent rows of guide blades serve in particular as cover elements which protect the inner housing 16 in the guide blade carrier or other housing installation parts from thermal overstress by the hot working medium M flowing through the turbine 6.

The combustion chamber 4 is configured in the exemplary embodiment as a so-called annular combustion chamber, in which a plurality of burners 10 arranged around the turbine rotor 8 in the circumferential direction open into a common combustion chamber space. For this purpose, the combustion chamber 4 is configured in its entirety as an annular structure, which is positioned around the turbine rotor 8 around.

FIG. 2 shows in detail a section through the outer periphery of a mounted on the turbine rotor 8 turbine disk a blade stage of the turbine unit 6 according to the prior art.

A blade 12 is arranged in a blade holding groove 30 with its blade root 32. The blade root 32 of the blade 12 is fir-tree-shaped in cross-section and corresponds to the Christmas tree shape of the blade holding groove 30. The schematic representation of the contour of the blade root 32 and the blade holding groove 30 is compared to the rest of the representation FIG. 2 played rotated by 90 °. Thus, the illustrated blade containment groove 30 extends between the side surfaces 34 of the turbine disk 36.

Furthermore, head ends of guide vanes 14 are schematically indicated, which - viewed in the flow direction of the working medium of the gas turbine - are arranged upstream and downstream of the rotor blade 12. The vanes 14 are arranged radially in wreaths. The vanes 14 of each ring are stabilized by a head side provided mounting ring 38. On both sides of the turbine disk 36, sealing disks 40 are used circumferentially on each of the side walls 34 in a scale-like manner. These are held on their upper side in a groove 42 introduced into the rotor blade 12 and fixed on its underside by a securing bolt 44.

On the one hand, they seal the gap between the turbine disk 36 and adjacent guide vanes 14 against penetration of hot working medium M out of the turbine by attached sealing vanes 46 which extend essentially in the axial and azimuthal direction. On the other hand, the sealing plates 40 also provide for an axial fixation of the blade root 32 in the blade root groove 30 and secure it against axial displacement. The radial and azimuthal securing has already been achieved by the Christmas tree shape of the blade retaining groove 30. Furthermore, the sealing plates 40 prevent leakage of cooling air channels 48 introduced through the turbine disk 36 into the blade root 32 and the rotor blade 12.

In order to allow a simpler, easier and cheaper construction of the gas turbine 1, the design should be changed so that the sealing plates 40 can be omitted. Such a construction in one of FIG. 2 appropriate way in FIG. 3 shown.

Again, the blade 12 and the adjacent vanes 14 can be seen with the corresponding attachments. In order to enable elimination of the sealing plates 40, 32 sealing wings 50 are on the one hand directly attached to the blade root. These prevent penetration of hot working medium from the interior of the gas turbine 1 into the areas in the vicinity of the turbine rotor. Furthermore, in order to ensure axial fixation of the blade root 32 of the blade 12 in the blade root groove 30, grooves 52 extending substantially azimuthally with respect to the turbine rotor are inserted in the blade root. These engage in springs 54 of the backup plate 56. The securing plate 56 is provided with folds 58, which engage in corresponding recesses 60 of the turbine disk 36. As a result, an axial fixation of the backup plate 56 on the turbine disk 36 and a fixation of the blade root 30 on the backup plate 56 is ensured.

Such a construction is also particularly easy to manufacture: For this purpose, the backup plate 56 is not folded before assembly so know so no bends 58. When mounting the springs 54 of the backup plate 56 are first inserted into the grooves 52. Subsequently, the blade root 32 is pushed into the blade holding groove 30 and the backup plate folded and thus fixed.

The backup plate 56 is enlarged again in FIG. 4 shown. Clearly visible are the springs 54 for fixing the blade root 32 of the blade 12 and the bends 58 for fixing on the turbine disk 36. The fuse plate 56 also has a number of cooling air holes 62, so that a passage of cooling air from the interior of the turbine disk 36 in the blade root 32 and in the blade 12 is ensured.

By the construction shown above, it is possible to completely eliminate the previously necessary sealing plates 40. All previously taken over by the sealing plates 40 tasks are taken over by other, adapted components. As a result, the relatively expensive to manufacture sealing plates 40 can be omitted and it is an overall lighter and cheaper construction of the gas turbine 1 possible.

Claims (5)

1. Turbine rotor (8) for a gas turbine,
   with a number of coolable rotor blades (12) which are assembled in each case to form rotor blade rows and arranged in each case on a turbine disk (36), having a blade root (32) in each case which is arranged in each case in an axially extending rotor blade retaining slot (30) of the turbine disk (36),
   wherein between the respective blade root (32) and a base of the rotor blade retaining slot (30) a locking plate (56) is arranged for securing rotor blades (12) against displacement along the rotor blade retaining slot (30), which locking plate is fixed on the turbine disk (36) by means of folds (58),
   characterized in that
   a cooling air feed passage (48) leads to the base of the rotor blade retaining slots (30) for feed of cooling medium, in that the respective locking plate (56) has a number of cooling air holes (62) for passage of cooling medium and
   in that the respective blade root (32) comprises two grooves (52) which extend essentially azimuthally with regard to the turbine axis and in that the respective locking plate (56) comprises two tongues (54),
   which are arranged in such a way that for sealing they can be connected to the grooves (52) of the blade root (32) in a form-fitting manner.
2. Turbine rotor (8) according to Claim 1,
   in which the respective blade root (32) has a sealing wing (50).
3. Turbine rotor (8) according to Claim 2,
   in which the respective sealing wing (50) extends essentially in the axial and azimuthal directions with regard to the turbine axis.
4. Turbine rotor (8) according to either of Claims 2 and 3,
   in which the respective blade root (32) has a sealing wing (50) in both axial directions.
5. Gas- and steam turbine plant with a turbine rotor (8) according to one of Claims 1 to 4.

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