WO2014146866A1

WO2014146866A1 - Sealing element for sealing a gap and corresponding gas turbine

Info

Publication number: WO2014146866A1
Application number: PCT/EP2014/053534
Authority: WO
Inventors: Pascal HINKEROHE; Frank Hoppe; Kevin KAMPKA; Dennis KICZA; Philipp KREUTZER; Jens Sander; Vyacheslav Veitsman; Jan Wilkes
Original assignee: Siemens Aktiengesellschaft
Priority date: 2013-03-20
Filing date: 2014-02-24
Publication date: 2014-09-25

Abstract

A sealing element (24) is provided for sealing a gap (22) between two components (12, 20) which can move thermally relative to each other and which each have a component slot (26, 28), said sealing element (24) being oriented along a main line and having, in a cross-section that is substantially perpendicular to the main line, a first end section (30) and a second end section (32) and a middle region (34) arranged between the end sections (30, 32). The sealing element is designed to ensure effective sealing also with radially comparatively large thermal expansions of the components and also reduce thermal stresses and the formation of cracks in the components. To this end, at least one of the end sections (30, 32) comprises fibers (36) arranged in a bundle-like manner.

Description

description

SEALING ELEMENT FOR SEALING A GAP AND RELATED GAS TURBINE

The invention relates to a sealing element for sealing a gap between two thermally mutually movable components, each having a Bauteilnut, wherein the sealing element is directed along a main line and in a direction substantially perpendicular to the main line cross section, a first end portion and a second end portion and one between the Having end portions arranged central region. It further relates to a gas turbine with such a sealing element.

A gas turbine is a turbomachine in which a pressurized gas expands. It consists of a turbine or expander, an upstream compressor and an intermediate combustion chamber. The principle of operation is based on the cycle process (joule process): this compresses air via the blading of one or more compressor stages, then mixes these in the combustion chamber with a gaseous or liquid fuel, ignites and burns. In addition, the air is guided in a secondary air system and used for cooling in particular thermally stressed components.

The result is a hot gas (mixture of combustion gas and air), which relaxes in the subsequent turbine part, with thermal converts into mechanical energy and first drives the compressor. The remaining portion is used in the shaft engine for driving a generator, a propeller or other rotating consumers. In the jet engine, on the other hand, the thermal energy accelerates the hot gas flow, which generates the thrust.

In gas turbines with high turbine inlet temperatures of in some cases more than 1000 ° C occur due to the high temperature difference between cold start and operation on thermal expansion of the individual components of the gas turbine, so that in order to avoid high thermal stresses and cracking adjacent components are partially spaced by a gap from each other. Since the secondary air system typically has a higher pressure than the hot gas channel, internal leaks of cooling air in the turbine occur at the gaps and cause losses of power and efficiency. In particular, this results at the gaps between platforms of Turbinenleitschaufein and ring segments, which limit the hot gas channel.

The leaks lead to increased energy consumption by the compressor and a difficult design calculation of the components. Another reason why leaks should be avoided concerns the true hot gas temperatures in the turbine: the more leakage losses are present, the higher the air consumption of the secondary air system and the less compressed air is therefore supplied to the combustion chamber. In this case, to produce a high turbine output, the inlet temperature must be set higher by supplying more fuel. As a result, however, the components are subject to higher loads and additional cooling is necessary. As a result, increased design effort and reduced turbine efficiency follow.

To minimize leaks, a variety of sealing concepts are used within the turbine as required. Usually, flat, in a main line along the respective gap, z. B. along the circumferential direction in radial gaps extending sealing elements in a groove, which is usually perpendicular or at a defined angle to be sealed gap, driven. In the simplest case, the sealing elements are designed as flat sealing elements with a smooth surface. Often also grooved or serrated sealing plates are used, which are also referred to as a riffle seal or comb profiled seal. This is a metal gasket having between two ends or end portions a central region with a smooth and a serrated or toothed surface and is known for example from EP 0 852 659 Bl. The toothed profile is deformed during assembly so far that after installation creates a virtually backlash-free connection between the grooved components and the sealing element. A disadvantage of said sealing elements, however, is that they are unsuitable for components that are subject to major radial displacements against each other, due to their lack of flexibility in the radial direction. It is therefore an object of the invention to provide a sealing element of the type mentioned which ensures an effective seal even with radially comparatively large thermal expansion of the components and yet reduces thermal stress and cracking of the components.

This object is achieved according to the invention in that at least one of the end sections comprises bundle-like arranged fibers. The invention is based on the consideration that the sealing elements used hitherto in particular allow a mobility of the components along their extension direction, typically in the axial direction. A higher flexibility of the sealing element would be achievable if the end sections of the sealing element were not designed as rigid sealing plates with applied grooves or the like, but would themselves be flexibly movable without being damaged themselves. This is possible by the configuration of the end sections made of flexible fibers. These are arranged like a bundle in the manner of a brush seal and can thus fill the corresponding component groove, so that the seal is improved. Furthermore, in this case both end sections comprise bundle-like arranged fibers. As a result, the described improved sealing is realized by filling the component grooves on both sides of the sealing element on each component involved.

In addition, the fibers extend through the middle region between the respective end sections. This allows a particularly simple production of the sealing elements. The sealing elements are hereby produced as a fiber bundle in the corresponding desired shape. The opposite end regions of the sealing element in this case correspond to the respective opposite ends of the fibers. The fibers are preferably exclusively in the middle region of a frame element. As a result, the shape of the sealing element is stabilized, since the frame element comprises the fibers. The frame member may include subdivisions or have only an opening for the passage of all fibers.

Furthermore, the frame element is advantageously at least partially made of a ceramic fiber composite material, so-called ceramic matrix composites (CMC). These are in a particularly good way to withstand the high temperatures and high temperature fluctuations in a gas turbine. At the same time, they are particularly crack-resistant and have insulating properties. In a further advantageous embodiment, a direction of extension of the fibers through the frame element with respect to the main line of the sealing element at an angle of less than 90 °, z. B. 45 °. This increases the flexibility of the sealing element, since the fibers thus lie obliquely in the gap and thus can adapt particularly well to a reduction of the gap width. In an advantageous embodiment, the sealing element expands from the central region to the end sections. For a sealing element that is straight in cross section, this results in

Essentially in a dumbbell shape of the sealing element. This can arise in combination with the embodiments described above in that a fiber bundle is encompassed by a frame element in the middle region and the fibers emerging from the frame element in the end sections are fanned out like a brush. As a result, a particularly good seal is achieved in the Bauteilnuten into which the end portions are introduced.

Advantageously, at least a part of the fibers consists of a metallic material. Metallic materials have the appropriate choice of materials a particularly good heat resistance, such. B. martensitic steels. Also, metallic fibers are particularly flexible and resistant to bending. In an alternative or additional advantageous embodiment, at least a part of the fibers consists of a ceramic material. Ceramic fibers, for example fibers based on aluminum oxide, silicon dioxide or silicon carbide, are particularly temperature-resistant and have high tensile strength and ductility.

A described sealing element is arranged in an advantageous embodiment in a gas turbine, which has a hot gas region and a cooling gas region to be sealed therefrom for cooling guide vanes of the gas turbine, wherein the sealing element engages in a Bauteilnut a first component and in a Bauteilnut adjacent to the first component second component , wherein between the components a gap is formed. The fibers arranged on the sealing element in the end section form within the groove a flexible shape following a thermal expansion of the component, which seals the cooling gas region in an excellent manner from the hot gas region. Here, the end section to be introduced into the respective component groove advantageously has a slight oversize relative to the component groove. As a result, the end section is already deformed during insertion without thermal expansion already taking place. As a result, regardless of the currently prevailing temperature in the gas turbine and the temperature difference between the cooling gas region and the hot gas-conducting region, an effective sealing of the gap is achieved.

In a further advantageous embodiment, the component groove, into which the sealing element engages, tapers away from the gap into the component. This facilitates assembly, since the sealing element can be inserted more easily into the component groove.

A gas turbine having a hot gas region and a cooling gas region to be sealed therefrom for cooling guide vanes, the regions being separated from one another by a plurality of components arranged in the circumferential direction and in the axial direction, and at least one first component and a second component being spaced by a gap, advantageously has one Component groove in the first component and component groove in the second component, in which the gap sealing a described sealing element is arranged.

The advantages achieved by the invention are, in particular, that a much better flexibility in the radial direction when sealing two axially spaced components in a gas turbine is made possible by a sealing element of a plurality of fibers which are bundled in the end region and optionally fanned out like a brush. The flexibility of the sealing element so as to minimize thermal stresses and prevents cracking. In addition, a better sealing effect is achieved by reliably closing the gap. Furthermore, the sealing element is characterized by its ease of installation and can in the known Bauteilnuten be used with an unchanged design of the components.

The invention will be explained in more detail with reference to the embodiment shown in the drawing. Show:

1 shows a detail of a longitudinal section through a

Gas turbine,

2 shows a cross section through a sealing element in the

Gas turbine,

3 shows a cross section through an alternative sealing element in the gas turbine, and

4 shows a plan view of the sealing element from FIG. 3

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

In FIG. 1, a detail of a gas turbine 1 is shown, which is aligned along an axis 2. The terms used below, such as axial, radial or circumferential direction, always refer to the axis 2 of the gas turbine 1.

The gas turbine 1 has in a housing 4 in the axial direction alternately vanes 6 and blades 8. The vanes 6 are directed along an axis 10 perpendicular to the axis 2 of the gas turbine and arranged along the circumference of the gas turbine 1 forming a circle. Such a circle of vanes 6 is also referred to as Leitschaufelrad. The vanes 6 are connected via a respective vane plate 12 to the housing 4 of the gas turbine 1 and are thus part of the stator of the gas turbine first

Along the periphery, adjacent vanes 6 are spaced apart from one another by a respective gap (not shown in detail), as a result of which they are largely free from thermal expansion. can stretch. The guide vane plate 12 separates a hot gas region 14 formed around the axis 2 of the gas turbine 1 from a cooling gas region 16 formed between the vane plate 12 and the housing 4. In the hot gas region 14, the hot gas previously burned in the combustion chamber, not shown, flows, while in the cooling air region typically bleed air flows from the End of the compressor flows.

The rotor blades 8 are stretched along a respective axis 18, which is also substantially orthogonal to the axis 2 of the gas turbine 1. The blades 8 lie completely in the hot gas region 11. They are arranged in a ring shape as a blade wheel on the rotor of the turbine rotating about the axis 2. A vane wheel is called a turbine stage together with the downstream impeller.

In the area of the rotor blades 8, the hot gas region 14 is separated from the cooling gas region 16 by a plurality of ring segments 20 along the circumference of the gas turbine 1. The ring segments 20 are each connected to the housing 4. For clarity, only one vane 6, a rotor blade 8 and a ring segment 20 are shown in each case. In the axial direction, a respective ring segment 20 is spaced from a respective vane 6, in particular the vane plate 12 by a gap 22. This gap 22 is sealed by a sealing element 24, which largely prevents a flow of cooling gas from the cooling gas region 16 into the hot gas region 14.

The guide vane 12 in this case represents a first component and the ring segment 20 is a second component. In the axial direction thus sealing the cooling gas region 16 of the hot gas region 14 between adjacent vanes 6 and ring segments 20 and in the circumferential direction in each case a seal between adjacent vanes 12 and accordingly between adjacent ring segments 20th In FIG. 2, the sealing element 24 is shown in the enlarged illustration of the region II from FIG. FIG. 2 shows a stator blade plate 12 and a ring segment 20 as two adjacent components, which are spaced apart from one another by the gap 22. The components may alternatively be two adjacent guide vanes 6, in particular guide vanes 12, as well as two adjacent ring segments 20. In the components, a component groove 26 or 28 is respectively introduced in the circumferential direction. The component groove 26 in the guide plate 12 is facing the ring segment 20, the component groove 28 in the ring segment 20 is the guide blade plate 12 facing. In the Bauteilnuten 26, 28 engages the gap 22 sealing a sealing element 24 a.

The sealing element 24 is aligned along a leading in the drawing, aligned in the circumferential main line and has in the illustrated cross section perpendicular to the main line a first end portion 30, a second end portion 32 and an intermediate central region 34. The first end portion 30, the central portion 34 and the second end portion 32 are in line and are each aligned in the radial direction. The first end section lies in the component groove 26 in the guide blade plate 12. The second end section 32 lies in the component groove 28 in the ring segment 20.

The sealing element is essentially constructed of fibers 36 which extend from the first end portion 30 to the second end portion 32 in the radial direction and form a fiber bundle. In the middle region 34, the fiber bundle is surrounded by a frame element 38, which limits the area filled with fibers 36 in the axial and circumferential direction. In the radial direction, the fibers 36 pass through the frame member 38 and in the respective end portions 30, 32. In the respective end sections 30, 32, the fibers fan out, so that in a dumbbell-shaped cross section of the

Sealing element 24 results. The radial extent of the frame member 38 is narrower than the radial width of the Bauteilnuten 26, 28. This results in a game with radial displacements of the components 12, 20 against each other. In the end sections 30, 32, the sealing element 24 has an excess in relation to the respective component groove 26, 28 due to the brush-like radial and circumferential fibers 36.

In the embodiment, the frame member 38 is made of a ceramic fiber composite material. It may have stabilization struts between its radial boundary walls. The fibers 36 are made of a metallic or also of a ceramic material. In an embodiment not shown, the component grooves 26, 28 taper from the gap 22 into the respective component 12, 20.

An alternative embodiment of the sealing element 24 is shown in FIGS. 3 and 4. This embodiment will be explained only with reference to their differences from the form shown in FIG.

First of all, the fibers 36 in the end sections 30, 32 in FIG. 3 and 4 are not fanned out in the manner of tufts, but extend largely straight into the component grooves 26, 28. This results in a more ordered arrangement of the fibers 36. Another difference results from FIG 4, which represents a plan view of the direction A shown in FIG 3 on the sealing element.

The direction of extension of the fibers 36, which are currently arranged, has an angle of 45 ° relative to the main direction of the sealing element running from top to bottom in FIG. They still extend in the radial-azimuthal plane of the gas turbine 1. This results an oblique arrangement of the fibers of the end portions 30, 32 in the Bauteilnuten 26, 28, so that they can easily feather and react flexibly to changes in size of the gap 22.

Claims

claims

1. sealing element (24) for sealing a gap (22) between see two thermally mutually movable components

(12, 20), each having a component groove (26, 28), said sealing element (24) being directed along a main line and having a first end portion (30) and a second end portion (32) in a substantially vertical cross-section. and a middle region (34) arranged between the end sections (30, 32),

characterized in that both end portions (30, 32) comprise bundle-like fibers (36) extending between the respective end portions (30, 32) through the central region (34) and in the central region (34) of a frame member (38 ) are included.

Second sealing element (24) according to claim 1,

wherein both end portions (30, 32) comprise bundle-like fibers (36).

3. sealing element (24) according to claim 1 or 2,

in which the fibers (36) are comprised exclusively in the middle region (34) of a frame element (38).

4. sealing element (24) according to claim 3,

in which the frame element (38) is at least partially made of a ceramic fiber composite material.

5. sealing element (24) according to any one of claims 1 to 4, wherein an extension direction of the fibers (36) relative to the main line has an angle of less than 90 °.

6. sealing element (24) according to one of the preceding claims,

which widens from the middle region (34) to the end sections (30, 32).

7. sealing element (24) according to any one of the preceding claims,

in which at least a part of the fibers (36) consists of a metallic material.

8. Sealing element (24) according to one of the preceding claims,

in which at least a part of the fibers (36) consists of a ceramic material.

9. gas turbine (1) with a hot gas region (14) and a cooling gas region (16) to be sealed therefrom for cooling guide vanes (6),

wherein the regions (14, 16) are separated from one another by a plurality of components (12, 20) arranged in the circumferential direction and in the axial direction and at least one first component (12) and a second component (20) are separated by a gap (22). are spaced apart and the first component (12) and the second component (20) have a Bauteilnut (26, 28), in which the gap (22) sealingly a sealing element (24) is arranged according to one of the preceding claims.

10. Gas turbine (1) according to claim 8,

in which the end section (30, 32) to be introduced into the respective component groove (26, 28) has a slight oversize relative to the component groove (26, 28).

11. Gas turbine (1) according to claim 8 or 9,

in which the sealing element (24) engages in a component groove (26, 28) which tapers away from the gap (22) into the component (12, 20).