EP2002085A1 - Guide blade segment of a thermal turbomachine, associated production method and thermal turbomachine - Google Patents

Abstract

The blade segment (2) has a set of profiled blades (6) arranged on a platform (8). A set of securing units (14) securing the guide blade segment to an associated guide blade support are arranged on a side of the platform, which is oriented away from the blades. A section of one of the securing units is a separately produced component, which is rigidly connected to the platform or to an additional section of the securing unit. An independent claim is also included for a method for manufacturing of a guide blade segment.

Description

description

Guide vane segment of a thermal turbomachine, associated production method and thermal turbomachine

The invention relates to a vane segment of an ther ^{¬ mischen turbomachine} , in particular a gas turbine, with at least one profiled on a platform profiled blade, wherein at the substantially flat, the

Airfoil side facing away from the platform a number of fasteners for attachment of the vane segment is arranged on an associated vane carrier.

Gas turbines are used in many areas to drive generators or work machines. Here, the energy content of a fuel to produce a Rotati ^¬ onsbewegung a turbine shaft used. For this purpose, the fuel is burned in a combustion chamber, compressed air being supplied by an air compressor. Produced in the Brennkam ^¬ mer by the combustion of the fuel, under high pressure and high-temperature standing working medium is guided via a standardized downstream of the combustion chambers Turbinenein- where it is work-expanded.

To generate the rotational movement of the turbine shaft, a number of rotor blades, which are usually combined into groups of blades or rows of blades, are arranged thereon, which conveyors, via a momentum transfer, out of the flow medium

Drive turbine shaft. For guiding the flow medium in the turbine unit are also usually disposed between Benach ^¬ disclosed blade rows to the turbine casing associated guide vane rows. The turbine blades, and in particular the guide vanes, the working fluid typically have a profiled, erstrecktes along a blade axis for the airfoil geeigne ^¬ th guidance on, to the end for attachment of the turbine blade at the respective Carrier body is formed transversely to the blade axis extending platform. The top of the platform facing the airfoil forms an outer boundary surface for the hot gas flow channel of the gas turbine.

For simple and secure mounting and fixing to a guide vane carrier connected to the turbine housing, the platform of the respective vane usually has a number of hook-like fastening elements on its underside or rear side facing away from the vane blade. A similar hook fastening of the axial space of two guide vanes of adjacent turbine stages bridging guide ring is known for example from EP 1 505 259 Al. For assembly, the vane is inserted with its fasteners or mounting hooks into corresponding receiving grooves of a vane carrier, aligned and then suitably, for. with the help of Stemmblechen, fixed. In the case of the aforementioned guide ring, according to EP 1 505 259 A1, an additional fastener is still provided by means of which the hook of the guide ring in the guide blade carrier can be further braced.

To reduce the manufacturing or assembly costs, a plurality of circumferentially of the gas turbine mutually adjacent vane blades of a row of guide vanes can be arranged on a common platform, so that the complete, hereinafter referred to as vane ^¬ segment blade unit using the platform-side mounting hooks axially or in Circumferential direction in the associated vane carrier is inserted. To simplify the speech, the term

"Leitschaufelsegment" in the following, especially in the claims, always include the case of a single vane with only one blade, unless this is not explicitly excluded. Usually, the vane, or the complete routing ^¬ is vane segment as part of a casting made are such that the platform and the platform side fastening elements ^¬ integral mitgegossene components of the guide vane fei or nozzle segment. In a first step, a so-called wax pattern of the blade or of the blade segment is manufactured, which is subsequently provided by such ^¬ derholtes dipping into a ceramic mass with a ceramic coating ^¬. Once this has a sufficient thickness, which is provided with the ceramic coating Wachsmo ^¬ dell is burned, wherein the ceramic solidifies and the liquefied or evaporated wax is removed. The ceramic negative mold obtained in this way is finally filled with the metallic blade material. After the solidification of the melt and the removal of the shell-like outer casting mold, ceramic core elements still remaining in the blade body, which were previously introduced to form cavities or cooling channels integrated in the blade body, are removed by leaching with sodium hydroxide solution or the like.

The hook-like protruding from the platform Befestigungsele ^¬ ments cause in the manufacturing process in more ^¬ terms difficulties. Already the production of the wax model is relatively complicated, since the formation of the

Fixing hook comparatively complex wax tools with a variety of so-called mask elements or slide are required. Also in terms of casting technology, the attachment hooks are problem areas, since the undercuts in the construction of the shell form can be sanded edges ^¬ NEN and in the subsequent casting process due to their exposed position always to form Lunkerfeldern, ie caused by heat shrinkage in the cooling component material defects tend.

In addition, it is often difficult to adhere to the neces sary for a snug fit of the mounting hook in the associated receiving groove ^¬ tolerances, especially in Ausfüh- variants with relatively small radii of curvature. Thus, sealing problems can occur at this point in the later operation of the turbine. Finally, it has been found that the fastening hooks often len also with respect to their wear characteristics at operating stress and in relation to the maximum permissible load receiving weak Stel ^¬ represent the turbine blades.

The invention is therefore based on the object of specifying a guide vane segment of the type mentioned, which is designed for simple and cost-effective production while avoiding casting problem zones for a particularly reliable and secure attachment to an associated vane carrier. Furthermore, a method suitable for the production of the vane segment should be specified.

With regard to the vane segment, the object is achieved in that at least one section of at least one of the fastening elements is a separately manufactured component which is fixedly connected to the side of the platform facing away from the airfoil.

The invention is based on the consideration that the casting material for the vane segment usually should be optimized to a high high-temperature strength back to stability as high operational safety and structural Sta ^¬ and a long service life of the immediacy ^¬ bar exposed to the hot working medium sections , In particular, the in the flow channel of the gas turbine hineinra ^¬ ing blade leaves and the flow channel facing the top of the platform to ensure. However, such an interpretation is, as has now been found, may not be optimal for the functionally and structurally decoupled from the rest of the blade segment Be ^¬ fastening elements including the hook, which are exposed on the one hand by the upstream platform only a comparatively low thermal load, however on the other hand have to absorb relatively high mechanical loads and bearing ^¬ or holding forces. In order to avoid the disadvantages existing up to now, it is proposed according to the concept presented here to separately produce the fastening elements that are functionally decoupled from the remainder of the stator blade segment, ie the fastening hook (s), using a material which has been consistently adapted to the respective technical function and only then with the aid of a suitable joining method with the rest of the fastener or with the platform of the example produced in the proven casting technique, ie integrally running, to connect the remaining vane segment.

For a permanent connection with the platform of the vane or nozzle segment of the respective Fixed To ^¬ restriction member preferably comprises a resting with a support surface on the back, the hot-gas side facing away from the platform connecting element. For a particularly uniform distribution of support or connecting forces and for precise alignment of the fastener relative to the platform, the connecting element is expediently designed in the manner of a flat connection plate with a flat support surface ^¬ . To realize a small installation height of the connection element or the connection plate may ver ^¬ lowers in a corresponding recess of the platform may be arranged, in particular, thereby an easy to manufacture stator blade segment can be specified, since the geometry are difficult to access for the Gußherstellung the Leitschaufelsegmenthaken has been eliminated.

It may be advantageous to manufacture only an outer, platform-remote section of the respective fastening element separately and to connect this outer section with an inner section formed on the platform, for example by means of a "compensating" joining, in particular by soldering As a result, the casting comprising the platform and the molded part of the fastening element can be made be made with comparatively coarsely selected tolerances. However, it is particularly advantageous to produce the complete fastening element as a separate component.

With this at least two-component design of the vane segment, not only can the material selection for the fastening elements be optimized with regard to the requirements of "hooked" attachment to the vane carrier, for example in terms of load bearing, wear and / or sealing; Despite the additional manufacturing step associated with the joining process, the production of the vane segment as a whole becomes much easier overall.

In a particularly expedient embodiment, the respective fastening element comprises a hook protruding from the platform, bent at an angle, which is adapted in its shape and contour to the associated receiving groove of a Leit ^¬ blade carrier. A possible alternative to this is a substantially straight profile piece that is moved into a polygonal inclusion in the turbine housing a ^¬.

Advantageously, the connecting element is positively fixed in a matched to the shape of the connecting element depression or groove of the platform. Such a positive connection is for example given by the fact that the platform in the edge region of the recess or the groove has a number of projections which ^engage around the Verbindungsele ^¬ ment each on its side facing away from the support surface. For mounting the fastening element to the platform, for example, the connecting element is then laterally lent into the recess or the receiving groove of the platform is inserted and then fixed in a suitable manner to the case ^¬ play positively, positively and / or cohesively, against lateral slipping. Because the connection forces are essentially by the projections positively embracing the connecting element are received, the additional fixation must be designed only for relatively low loads.

Instead of the positive connection between the connecting element and the platform or in addition thereto, a cohesive connection, preferably by soldering or welding, may be provided.

The respective fastening element for a high mechanical load capacity is preferably produced integrally from a one-component workpiece. In this case, for example, the attachment hook can be milled or extruded as a straight profile piece and bent in a second operation in the required radius. Preferably, the buildin ^¬ actuating element is made of a nozzle segment in comparison to the remaining less resistant to high temperatures, but made tougher material.

Conveniently, the guide vane or Leitschau ^¬ felsegment for secure attachment to the guide vane on a plurality of fasteners, preferably each of the fasteners is in the manner described above separately manufactured and ausgestaltetes component.

Typically, a gas turbine includes a plurality of turbine stages, each of the turbine stages including a plurality of stator vanes circumferentially around the flow passage on the turbine housing, which in their entirety form a row of vanes. In this case, as already gangs mentioned a ^¬, in each case a plurality of adjacent guide vanes to a guide blade segment or a "Mehrung" summarized in. Each of the guide vanes the or each vane ^¬ segment expediently has a platform with hakenarti ^¬ gen fastening elements, wherein the specifications for the hooking profile with regard to bending angle and / or bending dius usually vary with the installation position, ie in particular depend on the turbine stage or the guide vane row. It is particularly advantageous in the context sem ^¬ a normalized or standardized execution tion of the connecting elements and the corresponding platform side receptacles or recesses by means of which the fastening elements are connected to the respective platform. The respective profile piece from which the fastening hooks are bent can also look the same in the original "raw state" for all fastening elements One and the same fastening element can therefore be used in principle for all turbine stages of a turbine, only the bending radius and / or the bending angle of the turbine buildin ^¬ actuation hook must be adapted to the respective area of application and to the particular application. expediently, the bending of the profile piece before the Ver ^¬ connection of the connecting element with the platform of the master ^¬ shovel segment's because this tion handling and imple ^¬ the bending process In principle, however, it is also possible to bend the fastening hook into the desired or required shape only after the connection between the fastening element and the platform.

The advantages achieved by the invention are in particular in the following points:

The material selection for the fastener can be optimized to the Verhakungsanforderungen out, especially in terms of load bearing, wear and / or seal.

The production of the vane or the

Leitschaufelsegmentes is much easier. Tolerances can be set or adhered to more easily. - An interlocking profile can be used as a standard for all turbine stages / performance classes and adapted to the respective intended use by different bending radii. Casting problem areas are avoided in the casting. The wax tools for the vanes are simpler, have fewer inserts or slides.

The advantages outweigh even more than in a single blade at a vane segment with several ^¬ ren airfoils on a common platform.

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

1 shows a guide blade with a fastening element ge ^¬ Mäss a first embodiment;

2 shows a guide blade with a fastening element ge ^¬ according to a second embodiment, and

3 shows a guide blade with a fastening element ge ^¬ Mäss a third embodiment.

Identical parts are provided in all figures with the same Bezugszei ^¬ chen.

The illustrated in Figure 1 in a schematic side view cut-way and partially cut Leit ^¬ scoop 2 comprises a extending in the direction of the blade axis 4 profiled airfoil 6, to which in the region of the blade root a substantially transverse to the blade axis 4 oriented platform 8 is formed , In the installed state of the vane 2 which is oriented toward the blade 6 toward "top 10". At the side facing away from the blade 6 is substantially flat "underside" forms the platform 8 an outer Be ^¬ delimitation of a hot gas leading flow channel in a gas turbine (not shown) 12 or back of the platform 8 is a number of ha ^¬ kenartigen fasteners 14, by means of which the guide vane 2 in an associated vane support (not shown) mounted on the turbine housing / is attached. in the image section shown here is only one of the fastening elements 14 ^¬ visible, which is mounted with respect to the axial direction 16 near the trailing edge of the blade 6; another fastener is disposed in the vicinity of the leading edge not shown here.

The fastening element 14 is specifically adapted to the mechanical loads associated with the entanglement in the guide vane carrier in the case of a production that is simple and inexpensive. For this purpose, the fastener 14 is designed as a separate, independent of the remaining vane 2 and only subsequently connected to her component, wherein the material used for the fastener 14 ^¬ material is less resistant to high temperatures, but it is tougher than the material from which the blade 6 and Platt ^¬ form are made. 8

The fastening element 14 comprises in addition to a projecting from the rear ^¬ side 12 of the platform 8, approximately at right angles angled mounting hook 18 thereon a molded connection plate 20 with a rectangular base. The Verbin ^¬ manure plate 20 is positively deepening in an associated Ver ^¬ 21 of the platform 8 is fixed. With its flat bearing surface 22, the connecting plate 20 lies flat on the base surface of the recess 21. The depth of the recess 21 corresponds to the thickness of the connecting plate 20, so that in the edge area to the platform surface, an offset-free About ^¬ gear results.

To realize the positive connection two opposite Längskan ^¬ th 24 of the connecting ^plate 20 are chamfered in the embodiment shown in FIG 1 that they are encompassed by complementary, parallel to the longitudinal edges 24 extending projections 26 on the edge of the platform-side recess 21 or edged. The projections 26 thus form a perpendicular to the plane extending guide and mounting rail into which the connecting plate 20 for mounting the fastener 14th is inserted. In order to prevent unwanted slipping or shifting in this direction, additional fixing means, not shown here may be provided. A shift in the other two spatial directions, so on the one hand parallel to the blade axis 4 and the other in the axial direction 16 is excluded by the positive attachment. Corresponding bearing and holding forces are absorbed primarily by the bevelled longitudinal edges 24 of the connecting plate 20 and the corresponding platform-side projections 26. In correspondingly large elected edge length of the connecting plate 20 the effective forces in sections per lineal ^¬ are relatively small and therefore well be ^¬ herrschbar. It goes without saying that the person skilled in the art can modify numerous details of the connection between the fastening element 14 and the platform 20 without departing from the principle of positive locking shown in FIG.

The fastening element 14 shown in FIG. 2 is arranged sunk in a corresponding recess 21 of the platform 8 analogously to the fastening element 14 according to FIG. 1 with its connecting plate 20, but in contrast to this is not fixed in a form-fitting manner. Rather, the connection is ^¬ plate 20 integrally connected by a number of solder bumps or soldered joints 28 between the bearing surfaces 22 with the platform. 8 For the required high-temperature soldering a large number of solders / thermal treatments are commercially available, the geometry of the solder joints zweckmäßi ^¬ should be gerweise running all over. The selection of the soldering process is essentially influenced by the operating conditions at the soldering, the material pairing and the compatibility with other heat treatment requirements.

Finally, FIG 3 shows a variant in which only a äuße ^¬ res section 30 of the fastener 14 is a separately manufactured component, the rest of the part, however, integrally molded to the platform 8 and is cast together with it ^¬ sam. The effectively acting as an "adapter" outer portion 30 has much like a cap for a bottle or a pipe, a skirt 32, with which it encloses the platform-side component of the Befestigungsele ^¬ Mentes 14 at its outer end. The dimensioning ^¬ ments are chosen such that prior to the introduction of a joining agent results in a loose, play-afflicted seat that can be adapted to the present at the site geometric requirements and thereby compensates manufacturing tolerances and variations. After such a positional adjustment, the two components of the fastening element 14 are connected to one another by a soldering compound 36 introduced into the intermediate space 34 and subsequently solidified.

Claims

claims 1. vane segment (2) for a thermal Strömungsma ^¬ machine, with at least one on a platform (8) arranged profiled airfoil (6), wherein on the substantially flat the airfoil (6) facing away from the platform (8) a number of Fastening elements (14) for attachment of the vane segment (2) is provided on an associated guide vane carrier, characterized in that at least one portion of at least one of the fastening ^¬ elements (14) fixed to the the airfoil (6) facing away from the platform (8) connected, separately manufactured component is. 2. vane segment according to claim 1, wherein the respective fastening element (14) comprises a with a support surface (22) on the platform (8) resting connection element. 3. vane segment according to claim 1, wherein the respective fastening element (14) comprises a sunken with a support surface (22) in the platform (8) connecting element. 4. vane segment (2) according to claim 1, 2 or 3, wherein the complete fastening element (14) is a separately manufactured component. 5. vane segment (2) according to claim 4, wherein the fastening element (14) is made integrally from a one-component workpiece. 6. vane segment (2) according to claim 4 or 5, wherein the respective fastening element (14) is made of a compared to the platform (8) and / or to the airfoil (6) tougher material. 7. vane segment (2) according to one of claims 1 to 6, wherein the respective fastening element (14) comprises a of the platform (8) projecting fastening hook (18). 8. vane segment (2) according to one of claims 2 to 7, wherein the connecting element is a connecting plate (20). 9. vane segment (2) according to one of claims 3 to 8, wherein the connecting element is positively fixed in a matched to the shape of the connecting element recess (21) or groove of the platform (8). 10. vane segment (2) according to claim 9, wherein the platform (8) in the edge region of the recess (21) or the groove has a number of projections (26) which engage around the connecting element respectively on its side facing away from the support surface (22) , 11. vane segment (2) according to one of claims 1 to 10, wherein the fastening element (14) or its separately manufactured portion (30) cohesively, preferably by soldering, with the platform (8) or with the remaining part of the fastening element (14 ) connected is. 12. vane segment (2) according to one of claims 1 to 11, with a plurality of airfoils (6) on a common platform (8). 13. Thermal turbomachine, in particular gas turbine, with at least one vane segment (2) according to one of claims 1 to 12. 14. A method for producing a vane segment (2) according to any one of claims 1 to 12, wherein a fastening element (14) with a fastening hook (18) is made of a workpiece comprising an elongated profile piece by bending the profile piece by bending to the Fixing hook (18) is deformed, and wherein then the fastening element (14) non-positively and / or materially connected to the platform (8) is connected.