Combustion chamber of a gas turbine with optimised cooling

Abstract

The invention relates to a combustion chamber (01) of a gas turbine comprising a support structure (11) on the inside of which a plurality of heat shield tiles (06) are fastened on holding grooves (12a, 12b, 13a, 13b) by means of stone holders (07). Cooling-air bores and cooling-air openings (17, 18a) are provided in the support structure (11) in order to cool the support structure (11) and the stone holders (07), wherein an optimisation can be achieved through an off-centre arrangement of cooling-air openings (17b, 18a) in the holding grooves (12, 13).

Description

Description TITLE Combustion chamber of a gas turbine with optimized cooling TECHNICAL FIELD

[0001] The invention relates to the combustion chamber of a gas turbine, which is provided with a plurality of ceramic heat shield tiles, wherein the underside of the heat shield tiles is cooled with cooling air. BACKGROUND D

[0002] Very high temperatures of up to 1600 degrees Celsius occur in the combustion chambers of gas turbines. To ensure a long service life, combustion chambers with wall cooling are used. It is also known from the prior art to provide the combustion chambers with a heat shield on the inside, which advantageously withstands the hot gases. Due to thermal expansion and the large dimensions, the heat shield must be assembled from a large number of individual, generally ceramic heat shield bricks, which are attached to a support structure with a sufficient gap between them. This gap provides the heat shield elements with sufficient space for thermal expansion. However, since the gap also allows direct contact of the hot combustion gases with the metallic support structure and the retaining elements, cooling air is injected through the gap towards the combustion chamber as a countermeasure.

[0003] Typically, a heat shield comprises a support structure and a number of heat shield elements, each heat shield element having a cold side facing the support structure and a hot side opposite the cold side, which can be exposed to a hot medium. For fastening, in particular, ceramic heat shield elements, the support structure typically has retaining grooves to which the heat shield elements are releasably attached by means of retaining elements.

[0004] To protect the holding elements from hot gases and to flush the gaps between the heat shield elements, it is usually provided that cooling air is supplied into the holding grooves or directly between the supporting structure and the heat shield elements.

[0005] In order to achieve targeted use of the cooling air and thus minimize the cooling air requirement, it is known from WO 2014044376 A2 to provide at least some of the retaining elements with an integrated cooling air duct. For this purpose, a cooling air bore is located in the support structure exactly below one base end of the retaining element. Directly above the cooling air bore, the retaining element has an inlet opening, which merges into a cooling air path extending on both sides in the direction of the retaining groove. This allows the cooling air to be directed specifically to the thermally loaded retaining elements.

[0006] Although the cooling air duct integrated in the holding element can improve the cooling of the holding elements, there remains potential for optimization in order to achieve the most effective cooling at the required points with the least possible cooling air. SUMMARY OF THE INVENTION

[0007] The object is achieved by an embodiment of the invention according to the teaching of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0008] A generic combustion chamber is used in a gas turbine. The type of gas turbine is initially irrelevant, but it is usually a stationary gas turbine, particularly for power generation. The combustion chamber has a central combustion chamber axis and a combustion chamber inside. Accordingly, the side facing the combustion chamber defines the inside of the combustion chamber, and the opposite side is the outside.

[0009] Typically, the generic combustion chamber is a so-called annular combustion chamber or a silo combustion chamber.

[0010] A key component of the combustion chamber is a support structure that encircles the combustion chamber axis. A plurality of heat shield elements are arranged on the inside of the support structure. The heat shield elements comprise at least a plurality of heat shield tiles.

[0011] It is also possible to provide additional heat shield elements, for example, ceramic or metallic ones, which are not cooled according to the embodiment according to the invention. In this case, it can be provided that those circumferential rows of heat shield elements that experience a lower thermal load are designed as metallic heat shield elements. Furthermore, it may be necessary to use special ceramic or metallic tiles in circumferential rows with heat shield tiles, for example, if a regular heat shield tile, as the last heat shield element to be installed, cannot be mounted in the same way as the other heat shield tiles.

[0012] For the purposes of the present invention, heat shield tiles are those heat shield elements which are cooled by a cooling air supply according to the invention.

[0013] It is particularly preferred if the heat shield tiles comprise at least one circumferential row, possibly with the exception of one or two special tiles.

[0014] The heat shield tiles are preferably made of a ceramic material.

[0015] At least one burner is located at the upstream end of the combustion chamber, although a plurality of burners is typically used. At the downstream end of the combustion chamber is the exhaust port, which in a gas turbine typically forms the transition to the expansion turbine.

[0016] To secure the heat shield tiles and, if applicable, other heat shield elements, the support structure has several retaining grooves on the inside that run around the combustion chamber axis. These are spaced apart from each other in the axial direction, so that two retaining grooves are located under each heat shield tile.

[0017] The retaining grooves are T-shaped, with a cross-section as follows: In the center, there is a recess open to the inside. On both sides opposite the recess, there are engaging sections adjacent to the recess. The engaging sections are spaced from the inside-facing surface of the support structure. Each retaining section overlaps a corresponding engaging section facing the inside.

[0018] Corresponding to the arrangement of two retaining grooves under each heat shield tile and two engagement sections per retaining groove, each retaining groove has an inner engagement section on the side facing the center of the associated heat shield tile. Opposite the recess, there is an outer engagement section on the side facing away from the center of the associated heat shield tile. This means that the outer engagement section is located close to the corresponding edge of the heat shield tile in the axial direction, while the inner engagement section is further away from the corresponding edge.

[0019] The heat shield tiles are secured to the retaining grooves and thus to the supporting structure with block holders. For this purpose, a block holder is arranged on each retaining groove on the two circumferentially opposite sides of the respective heat shield tile. Accordingly, each heat shield tile is secured by four block holders. Advantageously, each stone holder is fixed with one end in the retaining groove and with the other end to the heat shield tile. The stone holders preferably engage with one end in the opposite engagement sections. This ensures The stone holders are movable along the retaining groove and largely fixed in the radial direction. The opposite end of the stone holder preferably engages in an engagement groove or pocket open to the longitudinal edge of the heat shield tile.

[0021] To protect the supporting structure, and in particular the block holders, from thermal damage, cooling air is directed through the supporting structure beneath and between the heat shield tiles. For this purpose, the supporting structure has a plurality of cooling air passages leading from the outside to the inside through the supporting structure, with the cooling air passages ending in cooling air holes or cooling air openings on the inside, as is typical.

[0022] The cooling air holes can be positioned at different locations and can therefore be located on the inside of the supporting structure between or next to retaining grooves or in the retaining grooves. In this case, it is advantageously possible to arrange at least some of the cooling air holes centrally in a retaining groove under the end of the stone holder engaging the heat shield tile. [0024J In order to improve the cooling air flow and thus to reduce the consumption of cooling air while at the same time ensuring sufficient cooling, the cooling air openings in the heat shield tiles are arranged in the region of the engagement sections and not, as is usual, in the region of the recess.

[0025] By arranging the cooling air openings in the engagement sections, it was surprisingly possible to achieve improved cooling air guidance with simultaneously lower cooling air consumption, while still achieving the required cooling and protection of the supporting structure and the stone holder. [0(.'26j In order to obtain the full advantageous effect, the cooling air openings are preferably arranged at a distance from the recess. For example, it can be provided that the cooling air openings are arranged centrally in the axial direction to the respective engagement section.

[0027] The cooling air openings are particularly preferably located on the side of the respective engagement section facing outwards.

[0028] Under each heat shield tile, there are two retaining grooves and thus four engagement sections. It is possible, for example, to provide one, two, or more, for example, four, cooling air openings under each heat shield tile.

[0009] A preferred embodiment is one in which at least some of the heat shield tiles have exactly one cooling air opening in one of the four engagement sections.

[0030] Furthermore, an embodiment is particularly preferred in which exactly two cooling air openings are present in the region of the engagement section under at least some of the heat shield tiles.

[0031] It is further particularly preferred that a cooling air opening be provided in the region of the engagement sections for each retaining groove. This means that a cooling air opening is provided for each heat shield tile in each of the two engagement sections of a retaining groove.

[0032] It can be provided that in one or more circumferential rows of heat shield tiles there is one cooling air opening each and in one or more circumferential rows of heat shield tiles there is one cooling air opening each in two engagement sections.

[0033] If there is a cooling air opening in each retaining groove of each heat shield tile, it is possible to arrange the cooling air opening in one of the two engagement sections. For this purpose, the arrangement is considered in the axial direction. For example, it can be provided that the cooling air openings are arranged in the inner engagement sections or at the downstream engagement sections or at the upstream engagement sections.

[0034] However, it is particularly preferred that the cooling air openings are arranged in the outer engagement sections. The arrangement has proven to be particularly advantageous in terms of low yet effective cooling air flow.

[0035] In principle, the cooling air openings can be provided at various locations along the circumferential direction of the retaining groove. However, the respective cooling air opening is particularly preferably located centrally in the circumferential direction under the corresponding heat shield tile. F&036] Deviating from the exact center position in the circumferential direction, minor deviations from the exact center position are irrelevant for the preferred arrangement of the cooling air opening in the circumferential direction at the center of the heat shield tile. On the one hand, a permissible deviation from the center of, for example, 5% of the length of the heat shield tile in the circumferential direction can be used as a reference. On the other hand, a distance from the center that is smaller than the distance from the cooling air opening to the nearest block holder can be considered a sufficiently centered arrangement. Furthermore, a deviation due to limited accessibility for producing the cooling air opening can be the reason for a deviation from the exact center. SHORT DESCRIPTION OF SIGNALS

[0037] FIG 1 shows a longitudinal section through a section of a gas turbine with an annular combustion chamber in the combustion chamber area.

[0038] FIG 2 sketches a perspective view of the combustion chamber from Fig. 1 .

[0039] FIG 3 outlines a section of the combustion chamber from Fig. 1 with the support structure and a heat shield tile.

[0040] FIG 4 outlines the fastening of the heat shield tile using a stone holder.

[0041] FIG 5 shows in detail a longitudinal section through the supporting structure with the retaining grooves and heat shield tiles and the cooling air opening.

[0042] FIG 6 shows a plan view of the arrangement of the cooling air opening in the supporting structure under the heat shield tiles. DESCRIPTION OF THE EMBODIMENT

[0043] Figure 1 shows a typical combustion chamber 01 in a longitudinal section through the gas turbine. A simplified representation of the upper section of the gas turbine in the combustion chamber area is shown.

[0044] In addition to Fig. 1, Figure 2 sketches the combustion chamber 01 in perspective view.

[0045] The combustion chamber 01 can be seen, which is designed as an annular combustion chamber. The combustion chamber 01 extends circumferentially around the combustion chamber axis 02, or in this case, the rotor axis of the gas turbine. At the upstream end of the combustion chamber 01, a plurality of burners 04 are arranged circumferentially around the combustion chamber axis. Opposite, at the downstream end, is the outlet opening 05, which also represents the transition to the downstream expansion turbine.

[0046] The essential component of the combustion chamber is the supporting structure 11, which in the case of the annular combustion chamber consists of an outer shell pointing away from the combustion chamber axis 02 and an inner shell pointing towards the combustion chamber axis 02.

[0047] On the inner side of the support structure 11 facing the combustion chamber, a plurality of heat shield tiles 06 and a plurality of additional heat shield elements are arranged. Typically, when using heat shield tiles, a row of heat shield tiles is formed in the circumferential direction, with the exception of one special tile. This applies to both the inner and outer shells of the support structure.

[0048] Figure 3 shows a section of the support structure 11 with the retaining grooves 12a, 12b, 13a, 13b running around the support structure 11. Retaining grooves 12, 13 are spaced apart from one another in the direction of the combustion chamber axis 02. Also visible is a heat shield tile 06, wherein the inside is covered all around by heat shield tiles for the operation of the combustion chamber - as shown in Fig. 2. It is intended that two retaining grooves 12, 13 are located under each heat shield tile 06. This means that in the row of heat shield tiles 06 - one of which is shown here - there are retaining grooves 12a and 12b, while for the following row of heat shield tiles 06 - not shown - the retaining grooves 13a and 13b are provided.

[0050] The heat shield tiles 06 are secured by block holders 07, which are shown displaced in the circumferential direction in this view. Reference is made to Figure 4, which shows the fastening of the block holder 07 to a recess on the longitudinal edge of the heat shield tile 06. The other end of the block holder 07 engages the retaining groove and is thus displaceable in the circumferential direction, but largely fixed in the radial direction.

[0051] The design of the retaining groove 12, 13 is obvious and has a T-shape. Reference is made to Figure 5 for this purpose. In the center of the retaining groove 12, 13 is a recess 14 open to the inside of the combustion chamber. Opposite on both sides, adjacent to the recess 14, is an engagement section 15 spaced apart from the top of the support structure 11. The engagement sections 15 are each covered toward the inside of the combustion chamber by a holding section 16 of the support structure 11. This enables the engagement of widened sections of the stone holders 07 into the opposite engagement sections 15, with the stone holders otherwise extending along the recess 14. Essential to the present invention is the arrangement of a cooling air opening 17b, 18a as a special cooling air bore on the inner side of the support structure 11. In this regard, it can be seen in Fig. 5 that the cooling air opening 17b, 18a is located on the engagement section 15.

[0053] In this preferred embodiment, a cooling air opening 17b, 18a is provided for each retaining groove 12, 13. An inner engagement section 15i is arranged on the side of each retaining groove 12, 13 which, viewed in the axial direction, is located on the side facing the center of the associated heat shield tile 06. Similarly, an outer engagement section 15a is arranged on the side of each retaining groove 12, 13 which, viewed in the axial direction, is located on the side facing the closest edge of the heat shield tile 06.

[0054] In this embodiment, it is provided that the cooling air openings 17b, 18a are located at the outer engagement sections 15a.

[0055] To supply the cooling air to the cooling air openings 17b, 18b, these are connected to the outside of the supporting structure 11 via cooling air passages 19. Figure 6 again shows a section of the combustion chamber 01 in plan view. The supporting structure 11 (located at the bottom of the illustration) can be seen in the partial section at the bottom right of the illustration. Also shown on the left side of the illustration is a heat shield tile 06, and the right side of the illustration without the heat shield tile shows the supporting structure 11 with the brick holders 07. The retaining grooves 12b, 13a extend circumferentially, with the central recess 14 and the engagement sections 15 on both sides. The brick holders 07 are fixed in the engagement sections 15. Essential for the invention is the arrangement of the cooling air openings 17b, 18a in the region of the engagement sections 15, wherein it is provided here that the cooling air openings 17b, 18a are always arranged in the outer engagement sections 15a. Furthermore, the illustration in Fig. 6 shows the arrangement of the cooling air openings 17b, 18a in the circumferential direction in the middle of an associated heat shield tile 06, here in the middle between two stone holders 07.

Claims

Claims What is claimed: 1 . Combustion chamber (01) of a gas turbine with a central combustion chamber axis (02) and an inner side and an outer side comprising - a supporting structure (11); and - at least one burner (04) arranged on an upstream side; and - an outlet opening (05) arranged on a downstream side; and - a plurality of heat shield tiles (06) and further heat shield elements; and - a plurality of retaining grooves (12a, 12b, 13a, 13b) which (12, 13) are arranged on the inside in the support structure (11) circumferentially around the combustion chamber axis (02) at a distance from one another in the axial direction and have a recess (14) open to the inside and opposite engagement sections (15i, 15a) adjacent to the recess, wherein the engagement sections (15) are each covered towards the inside by holding sections (16) of the support structure (11); and - several stone holders (07), which (07) are fixed in the respective retaining groove (12, 13) and on the associated heat shield tile (06); and - a plurality of cooling air openings (17b, 18a) open to the inside and further cooling air bores, which (17b, 18a) are connected to the outside via cooling air passages (19) penetrating the support structure (11); characterized in that the cooling air openings (17b, 18a) are arranged under the heat shield tiles (06) in the region of the engagement sections (15).

2. Combustion chamber (01) according to claim 1, wherein the cooling air openings (17b, 18a) are spaced from the respective adjacent recess (14).

3. Combustion chamber (01) according to claim 1 or 2, wherein one or two cooling air openings (17b, 18a) are provided under each heat shield tile (06).

4. Combustion chamber (01) according to claim 1 or 2, wherein under each heat shield tile (06) there is either a cooling air opening (17b, 18a) or a cooling air opening (17b, 18a) per retaining groove (12, 13).

5. Combustion chamber (01) according to one of claims 1 to 4, wherein an inner engagement section (15i) is arranged on the side facing away from the center of the associated heat shield tile (06) and an outer engagement section (15a) is arranged on the side of the associated Heat shield tile (06) is arranged, wherein the cooling air openings (17b, 18a) are each arranged in the outer engagement section (15a).

6. Combustion chamber (01) according to one of claims 1 to 5, wherein the cooling air openings (17b, 18a) are arranged centrally in the circumferential direction under the associated heat shield tile (06).

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