EP2342427B1 - Axial segmented vane support for a gas turbine - Google Patents

Description

The invention relates to a guide vane carrier, in particular for a gas turbine, which consists of a number of axial segments.

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 shaft. 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 shaft, a number of rotor blades, which are usually combined into blade groups or rows of blades, are arranged thereon and drive the turbine shaft via a momentum transfer from the working medium. 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 shaft burners in a common, surrounded by a high temperature resistant surrounding wall combustion chamber space. 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.

The vanes are fixed in each case via a blade root, also referred to as a platform, on a guide vane carrier of the turbine unit. In this case, the guide blade carrier for securing the platforms of the guide vanes comprise an insulation segment. Between the spaced apart in the axial direction of the gas turbine platforms of the guide vanes of two adjacent rows of vanes, a guide ring on the guide vane support of the turbine unit is arranged in each case. Such a guide ring is spaced by a radial gap of the blade tips of the fixed at the same axial position on the turbine shaft blades of the associated blade row. Thus, the platforms of the vanes and, in turn, optionally segmented in the circumferential direction of the gas turbine formed guide rings a number of the outer boundary of a flow channel for the working medium performing wall elements of the turbine unit.

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 at which the working fluid from the combustion chamber and flows into the turbine unit. Therefore, temperatures of about 1200 ° C to 1500 ° C are sought for such gas turbines and achieved.

At such high temperatures of the working medium, however, exposed to this components and components are exposed to high thermal loads. Therefore, in particular the guide vane carrier of the gas turbine usually made of cast steel. This is suitable to withstand the high temperatures within the gas turbine and it can thus ensure safe operation of the gas turbine.

Depending on the design target of the gas turbine while the vanes of the gas turbine can be attached either to a common vane carrier or there are separate axial segments for each turbine stage, for example as in the GB 1 051 244 A , intended. In any case, however, arise at least for large gas turbines, one or more very large castings, which require a correspondingly costly and technically complex construction. Furthermore, not all of the turbine vane carrier is exposed to the extremely high temperatures that require high heat resistant cast steel, but there is a temperature profile that has relatively small high temperature regions and a larger, low temperature rear region.

The invention is therefore based on the object to provide a guide vane, which allows a technically simpler design and more flexible adaptation to the prevailing at the vane carrier temperature profile while maintaining operational safety.

This object is achieved according to the invention by designing at least one axial segment as a lattice tube structure.

The invention is based on the consideration that a more flexible adaptation to the temperature profile within the gas turbine could occur in the area of the guide blade carrier, in particular by different materials of the individual axial segments of the guide blade carrier. In this case, high temperatures occur in particular in the region of the entanglement of the guide vanes and the ring segments, since these components ver a local heat input in the region of their attachment causes. Furthermore, the foremost region of the guide blade carrier is exposed to a comparatively high compressor end temperature. At these points, from a thermal point of view, a relatively high quality material is necessary. For large areas of the turbine carrier, the temperature resistance of this material is not required. These areas could consist of cheaper and less expensive material. In order to further reduce the weight of the vane carrier and thus allow a simpler design of the gas turbine, the axial segments should continue to be solid in areas of low temperature. Therefore, these axial segments should be formed as a lattice structure with a plurality of tubes, rods, bars, beams, profiles or the like, ie as interconnected, arranged in the manner of a lattice structure struts.

In an advantageous embodiment, the respective lattice structure is provided on its inner and / or outer side with a sheet metal lining. For a special simple construction of the guide vane carrier is possible. The embodiment with a sheet-metal-clad tubular construction can replace previously provided as castings sections of the vane support by a simpler structure, without jeopardizing the operational safety of the gas turbine. At the same time a smaller amount of material is needed.

Advantageously, the respective metal cladding on cooling air holes. Secondary air passes through these holes, thus ensuring particularly simple and reliable cooling of the inside of the guide blade carrier made of sheet metal. These holes are also easier to manufacture than the cooling air holes required for castings, whereby a finer distribution to the subsequent ring segments can be provided by increasing the number of holes with the same cross-section or flow resistance.

In a further advantageous embodiment, the material of the respective axial segment and / or optionally of the respective Sheet metal cladding adapted to local thermal and mechanical loads during operation. By such an adjustment a precise vote of the material used in each case for the castings and / or sheet metal cladding is guaranteed to the respective local temperature and force conditions. Areas exposed to particularly high temperatures should be made of a particularly high-quality and heat-resistant material, while comparatively more favorable material can be used in the cooler regions of the guide blade carrier.

Advantageously, a number of axial segments are welded together. By welding the individual axial segments, d. H. the individual lattice tube structures and the axial segments produced as castings a dimensionally stable and secure connection is ensured.

In a further advantageous embodiment, all axial segments are designed as a lattice tube structure. For a very simple construction of a guide vane carrier, the entire vane carrier can be designed as a lattice tube structure, where appropriate, different sheet metal linings are used on the inside, segment by segment. As a result, an even simpler construction of the guide vane carrier and thus the gas turbine is possible.

Advantageously, a gas turbine such a vane carrier and a gas and steam turbine plant comprises a gas turbine with such a vane carrier.

The advantages associated with the invention are, in particular, that a technically much simpler, easier and less expensive construction of a guide blade carrier and thus the entire gas turbine is possible by the design of an axial segment of a vane carrier as a lattice tube structure. In particular, more favorable materials can be used in areas with lower temperature exposure and cost-intensive high-temperature materials remain restricted to the front, hot area of the gas turbine. Furthermore, the remaining axial segments made of castings are comparatively smaller, allowing a simpler design of the vane carrier and the entire gas turbine.

Since the grid structure is less thermally conductive than a solid casting, also finds a lower heat conduction in the axial direction, in particular from the hot areas at the compressor exit in the rear cooler areas, resulting in improved cooling of the vane support and thus a lower axial and possibly also radial thermal Expansion is achieved. Thus, this design shows great potential for further development of guide vane carrier, as more flexible can be addressed to thermal and mechanical requirements. At the front of the turbine vane carrier, there are extremely stringent requirements for maintaining the gap to the vanes and blades to ensure turbine efficiency. With the segmentation by the tubular structure, the thermal expansion behavior can be set to a much better extent than before, and thus the necessary minimum gap can be reduced.

FIG 1

einen Halbschnitt durch die obere Hälfte eines Leitschaufelträgers, welcher aus einer Anzahl von Axialsegmenten besteht, und

FIG 2

einen Halbschnitt durch eine Gasturbine.

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

FIG. 1

a half section through the upper half of a vane support, which consists of a number of axial segments, and

FIG. 2

a half section through a gas turbine.

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

FIG. 1 shows in detail a half section through a guide vane carrier 1. In stationary gas turbines is the Leit Blade carrier 1 usually conical or cylindrical shaped and consists of two segments, an upper and a lower segment, the z. B. are interconnected via flanges. Only the section through the upper segment is shown.

The illustrated vane carrier 1 comprises a number of axial segments 24 which are welded together to form a solid structure. In order to enable a simpler and lighter construction of the guide blade carrier 1, which can also be flexibly adapted to the temperature conditions in the interior of the gas turbine 101, a number of axial segments 24 of the guide blade carrier 1 as a grid structure 26, also called lattice structure formed. The grid structures 26 are each provided on their inner side with a sheet metal lining 28. The struts of the grid construction can be designed with a variety of profiles such as round, square or otherwise as a hollow body or in solid construction.

The remaining axial segments 24 are formed as castings 30. In this case, the material of the cast parts 30 and the sheet metal linings 28 is in each case adapted to the thermal conditions in their respective region in the interior of the gas turbine. As an alternative to the figure shown, a complete construction of the vane support 1 made of grid segments would also be possible.

The gas turbine 101 according to FIG. 2 includes a compressor 102 for combustion air, a combustion chamber 104 and a turbine unit 106 for driving the compressor 102 and a generator, not shown, or a working machine. For this purpose, the turbine unit 106 and the compressor 102 are arranged on a common turbine shaft 108, also referred to as a turbine runner, to which the generator or the working machine is also connected and which is rotatably mounted about its central axis 109. The running in the manner of an annular combustion chamber combustion chamber 104 is provided with a number of Burners 110 equipped for the combustion of a liquid or gaseous fuel.

The turbine unit 106 has a number of rotatable blades 112 connected to the turbine shaft 108. The blades 112 are annularly disposed on the turbine shaft 108 and thus form a number of blade rows. Furthermore, the turbine unit 106 includes a number of stationary vanes 114, which are also attached in a donut-like manner to a vane support 1 of the turbine unit 106 to form rows of vanes. The blades 112 serve to drive the turbine shaft 108 by momentum transfer from the turbine unit 106 flowing through the working medium M. The vanes 114, 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 114 or a row of vanes and a ring of blades 112 or a blade row is also referred to as a turbine stage.

Each vane 114 has a platform 118 which is arranged to fix the respective vane 114 to a vane support 1 of the turbine unit 106 as a wall element. The platform 118 is a thermally comparatively heavily loaded component, which forms the outer boundary of a hot gas channel for the turbine unit 106 flowing through the working medium M. Each blade 112 is fastened to the turbine shaft 108 in an analogous manner via a platform 119, also referred to as a blade root.

Between the spaced-apart platforms 118 of the guide vanes 114 of two adjacent guide blade rows, a guide ring 121 is arranged on the guide blade carrier 1 of the turbine unit 106. The outer surface of each guide ring 121 is also the hot, the turbine unit 106 flowing through the working medium M and radially spaced from the outer end of the opposed blades 112 by a gap. The guide rings 121 arranged between adjacent rows of guide blades serve in particular as cover elements which protect the inner housing in the guide blade carrier 1 or other housing built-in components against thermal overstress by the hot working medium M flowing through the turbine 106.

The combustion chamber 104 is configured in the exemplary embodiment as a so-called annular combustion chamber, in which a plurality of burners 110 arranged around the turbine shaft 108 in the circumferential direction open into a common combustion chamber space. For this purpose, the combustion chamber 104 is configured in its entirety as an annular structure, which is positioned around the turbine shaft 108 around.

By using a guide vane carrier 1 of the embodiment given above, an optimal matching of the material to the temperature conditions in the interior of the gas turbine 101 is ensured. Parts closer to the compressor, which are subjected to a correspondingly higher temperature, ie in the FIG. 2 the leftmost axial segments 24 are accordingly made of a high temperature resistant material than in the gas channel downstream areas. The lattice structure furthermore ensures good thermal insulation of the individual cast parts 30 from one another, as a result of which thermal deformations can be minimized.

Claims (8)

1. Stator blade carrier (1)
   for a gas turbine (101), which consists of a number of axial segments (24),
   characterized in that at least one axial segment (24) is designed as a tubular lattice structure (26).
2. Stator blade carrier (1) according to Claim 1,
   in which the respective tubular lattice structure (26) is provided with a metal casing (28) on its inner and/or outer side.
3. Stator blade carrier (1) according to Claim 2,
   in which the respective metal casing (28) has cooling air holes.
4. Stator blade carrier (1) according to one of Claims 1 to 3,
   in which the material of the respective axial segment (24) and/or, if applicable, of the respective metal casing (28) is adapted to the local thermal and mechanical loads which are envisaged during operation.
5. Stator blade carrier (1) according to one of Claims 1 to 4,
   in which a number of axial segments (24) are welded to each other.
6. Stator blade carrier (1) according to one of Claims 1 to 5,
   in which all the axial segments (24) are designed as a tubular lattice structure (28).
7. Gas turbine (101) with a stator blade carrier (1) according to one of Claims 1 to 6.
8. A gas- and steam turbine plant with a gas turbine (101) according to claim 7.

Images