INNER HOUSING HUB FOR A GAS TURBINE

Abstract

An inner housing hub is arranged in a gas turbine about a gas turbine shaft and is formed as a component of an inner housing used to deflect hot gases exiting combustion chambers towards a turbine inlet region arranged in the direction of the gas turbine shaft. The inner housing hub includes at least one substantially cylinder casing-shaped securing portion having a cylinder casing-shaped main part, which has a hot side facing a hot gas path and a cold side facing away from the hot gas path. At least one web-shaped protrusion extends along the cold side and is arranged on the cold side on the main part in order to secure the inner housing hub. The web-shaped protrusion is made of a first material and the main part is made of a second material, the first material having a greater thermal expansion coefficient than the second material.

Description

FIELD OF INVENTION

The invention relates to an inner housing hub for a gas turbine. The inner housing hub can be arranged in the gas turbine around a gas turbine shaft and, as a component of an inner housing, is used together with the inner housing to deflect hot gases exiting combustion chambers toward a turbine inlet region arranged in the direction of the gas turbine shaft. Thus, the hot gases to be deflected impinge upon the inner housing hub on the side facing away from the gas turbine shaft.

The inner housing hub comprises at least one fastening portion substantially in the form of a cylindrical shell having a main body in the form of a cylindrical shell, on which the inner housing hub is fastened on a suitably designed fastening component of the gas turbine. In this context, the term “in the form of a cylindrical shell” is not to be taken in the strictly mathematical sense. The fastening portion and the main body are designed as tubular walls. Thus, the term “in the form of a cylindrical shell” refers only to the encircling shape of the wall and not to the thickness of the wall. For example, the fastening component can be a component part fastened indirectly on an outer housing of the gas turbine. The main body of the inner housing hub has a hot side facing a hot gas path and a cold side facing away from the hot gas path. Thus, the cold side faces the gas turbine shaft. At least one web-shaped projection extends along the cold side and is arranged on the cold side of the main body in the form of a cylindrical shell to enable the inner housing hub to be fastened.

BACKGROUND OF INVENTION

Fastenings of this kind are common, particularly with components of the combustion chamber housing or of the inner housing of gas turbines having silo combustion chambers.

In this case, the web-shaped projection is part of a slot and key joint between the main body in the form of a cylindrical shell and the fastening component. For example, the web-shaped projection can form the key and, for the purpose of fastening, can be arranged in a slot extending in the fastening component. However, the web-shaped projection could also form the slot of the slot and key joint if there is a slot extending in its upper side corresponding to a correspondingly formed key on the fastening component.

Owing to the operational temperature differences between the hot side and the cold side, the inner housing hub of the type in question is subject to high thermal stresses, especially in the region of the fastening portion. These thermal stresses can be transferred from the main body to a thermal protection means arranged on the hot side. The thermal protection means can be a thermal insulating layer, for example, in particular a ceramic protective layer. Particularly in the region of the fastening portion, this leads to high wear on the inner housing hub owing to start-stop-driven fatigue cracks with subsequent growth of the cracks and flaking of the thermal protection means off the hot side of the main body.

SUMMARY OF INVENTION

It is an underlying object of the invention to indicate an inner housing hub of the type stated at the outset which is subject to reduced wear.

According to the invention, this object is achieved, in the case of an inner housing hub of the type stated at the outset, by virtue of the fact that the web-shaped projection is made of a first material and the main body is made of a second material, wherein the first material has a greater thermal expansion coefficient than the second material, with the result that, in at least one operating state of the gas turbine, the thermally induced stresses are reduced in the region of the fastening portion in comparison with an integral design of the main body and the web-shaped projection made of the second material.

Thus, according to the invention, it is not that thermal protection on the hot side is improved to reduce wear but that the design of the main body is improved to reduce thermal stresses. According to the invention, the main body is no longer formed integrally with the projection. The projection and the main body are produced from different materials. For example, the two can be produced separately and joined together by welding or brazing. Here, the web-shaped projection projecting from the main body in the form of a cylindrical shell, which is thus colder than the remainder of the main body, is manufactured from a material which has a higher thermal expansion coefficient than the warmer main body. Owing to the greater thermal expansion coefficient, the projection no longer constricts the main body or no longer does so to the same extent. However, it is also the case that the thermal expansion coefficient selected should not be so great that the colder projection expands to a significantly greater extent than the main body during operation, despite a smaller temperature difference in the region of the projection. The first material and the second material are therefore chosen in such a way that they satisfy the demands on the inner housing hub and the fastening and, according to the invention, the different thermal expansion coefficients are such that the thermally induced stresses in the region of the fastening portion are reduced as compared with an integral design of the main body and the web-shaped projection made of the second material. The main body can have one or more web-shaped projections designed in accordance with the invention.

The inner housing hub is exposed to high temperature differences between the hot and the cold side of the main body, and therefore the design according to the invention of the fastening portion of the inner housing hub makes possible a significant extension of the service life of the inner housing hub. It is advantageously possible to envisage that, for the fastening of the inner housing hub in the gas turbine, said hub can be fastened on a fastening component in such a way that the web-shaped projection can be arranged in a slot surrounded by the fastening component.

The web-shaped projection thus forms the key of the slot and key joint.

The main body can comprise one or more web-shaped projections designed in accordance with the invention. These can, for example, be arranged in a row along the longitudinal extent on the cold side and form a common, subdivided web that can be arranged in a slot in the fastening component.

It can also be regarded as advantageous that the fastening portion is a housing wall, which is arranged around a center line and around which the hot gas path flows, with the result that the hot side of the main body faces away from the center line.

Owing to its small extent perpendicularly to the wall, a fastening portion designed as a housing wall is particularly susceptible to bending caused by thermal stresses. The wear of such gas turbine components can be reduced to a particularly great extent by means of the invention.

Another advantageous embodiment of the invention can provide for the inner housing hub to be designed substantially in the form of a cylindrical shell, at least in the region of the fastening portion, and for the at least one web-shaped projection to be arranged on the main body along a circular circumferential line, with the result that a web which is continuous or divided into segments or is in the form of a discontinuous ring is arranged on the cold side.

It can also be regarded as advantageous that the inner housing hub can be arranged with one end in a turbine inlet region, wherein the fastening portion is arranged in the region of the end.

It is another object of the invention to indicate an inner housing of the type stated at the outset having an inner housing hub, which housing is subject to reduced wear.

For this purpose, the inner housing hub is designed as claimed.

It is another object of the invention to indicate a gas turbine which is subject to reduced wear.

For this purpose, the gas turbine comprises at least one inner housing as claimed.

Further expedient embodiments and advantages of the invention form the subject matter of the description of illustrative embodiments of the invention with reference to the figure of the drawing, wherein the same reference signs refer to component parts which act in the same way.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing:

FIG. 1 shows schematically a longitudinal section through a gas turbine according to the prior art,

FIG. 2 shows schematically an inner housing hub in accordance with an illustrative embodiment of the invention in a perspective view,

FIG. 3 shows schematically a detail of the inner housing hub illustrated in FIG. 2, in a longitudinal section,

FIG. 4 shows schematically a detail of the inner housing hub illustrated in FIG. 2 with a fastening component arranged on the projection, in a longitudinal section, and

FIG. 5 shows schematically an inner housing of a gas turbine having an inner housing hub, which is designed in accordance with FIG. 2, in a perspective view.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a schematic sectional view of a gas turbine 1 according to the prior art. In the interior, the gas turbine 1 has a rotor 3, which is mounted so as to rotate about an axis 2 of rotation, has a shaft 4 and is also referred to as a turbine wheel. Along the rotor 3 there follow in succession an intake housing 6, a compressor 8, a combustion system 9 having at least one combustion chamber 10, a turbine 14 and an exhaust housing 15. The one or more combustion chambers 10 each comprise a burner arrangement 11 and a housing 12, which is lined with a thermal protection means 20 for protection against hot gases. The at least one combustion chamber 10 can be an annular combustion chamber. As an alternative, the gas turbine can also comprise one or more tubular combustion chambers or silo combustion chambers.

The combustion system 9 communicates with a hot gas duct, e.g. an annular hot gas duct. There, a plurality of turbine stages arranged in series form the turbine 14. Each turbine stage is formed by blade rings. As seen in the direction of flow of a working medium, a row formed by guide vanes 17 is followed in the hot duct by a row formed by rotor blades 18. Here, the guide vanes 17 are secured on an inner housing of a stator 19, whereas the rotor blades 18 of a row are attached to the rotor 3 by means of a turbine disk, for example. A generator (not shown) is coupled to the rotor 3, for example.

During the operation of the gas turbine, air is drawn in and compressed by the compressor 8 via the intake housing 6. The compressed air made available at the turbine end of the compressor 8 is passed to the combustion system 9 and is there mixed with a fuel in the region of the burner arrangement 11. The mixture is then burnt with the aid of the burner arrangement 11, forming a working gas flow in the combustion system 9. From there, the working gas flow flows along the hot gas duct past the guide vanes 17 and the rotor blades 18. The working gas flow expands across the rotor blades 18, transferring momentum, with the result that the rotor blades 18 drive the rotor 3, and the latter drives the generator (not shown) coupled to it.

FIG. 2 shows an inner housing hub 24 according to the invention for a gas turbine in accordance with an illustrative embodiment, in a perspective view. The inner housing hub 24 is designed in the form of a cylindrical shell with a center line 26. One end region of the inner housing hub forms a fastening portion 28. The fastening portion 28 in the form of a cylindrical shell comprises a main body 30 in the form of a cylindrical shell, which comprises a hot side 34 facing a hot gas path (indicated schematically by the arrow 32) and a cold side 36 facing away from the hot gas path. The hot side 34 can be coated with a thermal protection means (not shown). A web-shaped projection 38 is arranged on the main body 30 to enable it to be fastened to the inner housing hub 24.

The web-shaped projection 38 extends along a circular circumferential line along the cold side 36 of the main body and is arranged on the cold side of the main body 30 in the form of a cylindrical shell, and it is therefore arranged as an encircling annular web on the cold side 36. To fasten the inner housing hub 24 on a fastening component (not shown), the annular projection 38 is arranged in an annular slot (not shown) extending in the fastening component. For this purpose, the inner housing hub 24 can be constructed from two half-shells, which are initially brought separately into contact with the fastening component (not shown) and then joined together. In this case, the encircling web-shaped projection 38 is divided into segments.

In the illustrative embodiment shown, the fastening portion 28 is a housing wall 40, which is arranged around a center line 26 and around which the hot gas path 32 flows, with the result that the hot side 34 faces away from the center line 26. Apart from the web-shaped projection, the overall inner housing hub 24 can correspond to the construction of the fastening portion, thus to a certain extent allowing a free choice in the subdivision of the inner housing hub into a fastening portion up to line 42 in the illustrative embodiment.

FIG. 3 shows a detail of the inner housing hub shown in FIG. 2, in a longitudinal section in the region of the fastening portion 28. The fastening portion 28, which is designed in the form of a housing wall 40, comprises a main body 30 in the form of a cylindrical shell having a hot side 34 and a cold side 36. The hot side is coated with a thermal protection means 44. A web-shaped projection 38, the cross section 46 of which can be seen in the figure, is arranged on the cold side 36. According to the invention, the web-shaped projection 38 consists of a first material, and the main body 30 consists of a second material, wherein the first material has a greater thermal expansion coefficient than the second material, with the result that the thermally induced stresses in the region of the fastening portion 28 are reduced, as compared with an integral design of the main body 30 and of the web-shaped projection 38 consisting of the second material, in at least one operating state of the gas turbine. High thermal stresses are produced particularly around the transitional region of the main body and the web-shaped projection 38 during the operation of the integral design of fastening section known from the prior art.

FIG. 4 shows a detail of the inner housing hub 24 shown in FIG. 2 in the region of the fastening portion 28, in a longitudinal section. For the sake of simplicity, only the main body 30, together with the web-shaped projection 38, of the fastening portion 28 is shown. (The thermal protection means 44 arranged on the hot side 34 has been omitted in the figure). Extending opposite the hot side 34 is the cold side 36 of the main body 30, wherein the web-shaped projection 38 is arranged on the cold side 36 in the region of the end 50 of the main body 30. To fasten the fastening portion 28 on a fastening component 48, the web-shaped projection 38 is arranged in a slot 52 extending in the fastening component 48. The slot 52 and the web-shaped projection 38 form a slot and key joint, which fixes the position of the fastening portion 28 and hence the position of the inner housing hub 24 in a turbine inlet region 54, the inner housing hub 24 thus being arranged with one end 50 in a turbine inlet region 54.

FIG. 5 shows an inner housing 56 of a gas turbine having an inner housing hub 58 according to the invention arranged centrally in the inner housing. The inner housing hub 58 surrounds a gas turbine shaft (not shown) extending along the center line 26. The inner housing 56 has two inlets 60 and 62 and an annular outlet 64. The inner housing is closed on the rear side 66. The inlets 60 and 62 can each be arranged at one combustion chamber outlet of a combustion chamber (not shown). The outlet 64 can be arranged in a turbine inlet region (not shown). The inner housing 56 serves to deflect the hot gases exiting the two combustion chambers along the hot gas path 32, which is indicated schematically by an arrow. Here, some of the hot gases flow through the inner housing along the inner housing hub 58, which is sheathed with a thermal protection means 44. To fasten the inner housing, the inner housing hub 58 is, inter alia, fastened on a fastening component (not shown) surrounded by the hub in the region of the end 50 of said hub by means of the web-shaped projection 38 arranged around the cold side 36. To ensure that the cold projection 38 does not constrict the inner housing hub during operation, the inner housing hub 58 is designed in accordance with the invention. This protects especially the thermal protection means 44 from flaking off and thus protects the main body, arranged thereunder, of the fastening portion from premature wear.

Claims

1. An inner housing hub for a gas turbine, wherein the inner housing hub can be arranged in the gas turbine around a gas turbine shaft and is designed as a component of an inner housing, wherein the inner housing hub together with the inner housing is used to deflect hot gases exiting combustion chambers toward a turbine inlet region arranged in the direction of the gas turbine shaft, comprising: at least one fastening portion substantially in the form of a cylindrical shell having a main body in the form of a cylindrical shell, which comprises a hot side facing a hot gas path and a cold side facing away from the hot gas path,at least one web-shaped projection that extends along the cold side and is arranged on the cold side of the main body to enable the inner housing hub to be fastened,wherein the web-shaped projection comprises a first material and the main body comprises a second material, wherein the first material has a greater thermal expansion coefficient than the second material,such that, in at least one operating state of the gas turbine, the thermally induced stresses are reduced in the region of the fastening portion in comparison with an integral design of the main body and the web-shaped projection made of the second material.

2. The inner housing hub as claimed in claim 1, wherein for the fastening of the inner housing hub in the gas turbine, said hub can be fastened on a fastening component in such a way that the web-shaped projection can be arranged in a slot surrounded by the fastening component.

3. The inner housing hub as claimed in claim 1, wherein the fastening portion is a housing wall, which is arranged around a center line and around which the hot gas path flows, with the result that the hot side faces away from the center line.

4. The inner housing hub as claimed in claim 1, wherein the inner housing hub is designed substantially in the form of a cylindrical shell, at least in the region of the fastening portion, and the at least one web-shaped projection is arranged on the main body along a circular circumferential line, such that a web which is continuous or divided into segments or is in the form of a discontinuous ring is arranged on the cold side.

5. The inner housing hub as claimed in claim 1, wherein the inner housing hub can be arranged with one end in a turbine inlet region, wherein the fastening portion is arranged in the region of the end.

6. An inner housing comprising: an inner housing hub,wherein the inner housing hub is designed as claimed in claim 1.

7. A gas turbine, comprising: an inner housing as claimed in claim 6.