EP1939529A1 - CMC-liner for a combustion chamber in double layer design - Google Patents

Abstract

The combustion chamber lining of gas turbine has a gas-permeable heat protective layer (1) that faces the hot gas side and a carrier layer (2) that is separated from the heat protective layer by a displacement element (3). The heat protective layer and the carrier layer are made of fiber-reinforced ceramic, particularly fiber and matrix material that are selected from the groups aluminum silicates, yttrium silicates, yttrium aluminum garnet, mullite, aluminum oxide, silicon dioxide, silicon carbide, borosilicon carbonitride, silicon carbon nitride, carbon, silicon nitride, zirconium oxide. An independent claim is also included for a method for producing a combustion chamber lining, which involves producing a carrier layer, a displacement element and the heat protective layer.

Description

The invention relates to a combustion chamber lining of gas turbines and to a method for producing this combustion chamber lining.

Usually combustor liners of gas turbines are either single-layered or two different layers are provided in direct contact with each other, so that in both cases only a relatively low rigidity can be achieved and thus relatively high layer thicknesses of the individual layers are required. This results, on the one hand, in an unnecessarily high weight of the combustion chamber lining and, on the other hand, in inefficient cooling of the layer which is in direct contact with the hot gas in combustion chambers of gas turbines. Known combustion chamber linings are also often realized with the help of shingles, which must, however, compensate for the pressure difference between cooling air on its back and the hot gas side, which is why relatively high wall thicknesses are necessary for these shingles. Also, self-supporting heat protection layers (liners) are known. However, these typically have a low rigidity and accordingly a high susceptibility to vibration.

EP 1152191 A2 describes a combustion chamber with a lining of ceramic matrix composite materials (CMCs, Ceramic Matrix Composite material), wherein the heat protection layers over the entire surface in contact with other layers and therefore have a relatively low stiffness. Due to the self-supporting assembly of these combustion chamber linings they are therefore particularly susceptible to vibration.

EP 0943867 B1 describes a combustion chamber lining with the hot gas facing heat protection layer as a hollow chamber. Although these hollow chambers can be traversed longitudinally with cooling air. However, the walls of the hollow chambers are not made gas-permeable, so that the cooling air can not be supplied to the combustion chamber.

US 5,113,660 A describes a combustion chamber lining in which heat shield shingles are mounted on a carrier layer. These shingles lie all over the carrier layer, so that the back of the shingles can not be cooled directly with cooling air.

Also DE 19730751 A1 describes a combustion chamber lining, in which the heat protection layer is realized by ceramic components, which in turn rest directly on the entire surface of a carrier layer. Again, the back of the heat protection layer can not be cooled directly by cooling air.

DE 4114768 A1 describes a heat shield of a plurality of stones, the substantially full area on a full surface Carrier layer rest. Again, a direct cooling of the back of the stones does not take place.

DE 19502730 A1 describes a ceramic lining for combustion chambers, in which the layer facing the hot gas is connected in its entirety with a carrier layer by means of screws or bolts. Again, a direct, rear cooling of the heat protection layer does not take place.

US 5,553,455 A describes a combustion chamber lining in which various heat protection shingles are arranged over their entire surface on a carrier layer. Again, the back of the shingles can not be cooled directly.

US 2002/0184891 A1 describes a single layer heat protection layer which is relatively thick to limit susceptibility to vibration by sufficient rigidity.

EP 1128131 A1 describes a heat shield element in a combustion chamber of a gas turbine, in which the heat shield element is fastened as a shingle with fastening elements on a carrier layer. Since the carrier layer is not broken, no cooling air can be brought to the back of the shingles.

US 5,291,731 A describes a combustor liner of gas turbines in which a heat-shielding layer is formed from a backing layer by a system of grooves resting on the heat-shielding layer and in the carrier layer introduced pin is separated. However, such a fastening system prevents the lateral relative movement of the heat protection layer to the carrier layer. Characterized in that the support layer is provided in the described combustor lining of metal, while the heat protection layer consists of a ceramic material and both materials have different thermal expansion coefficients, it can lead to considerable mechanical stresses in this system. In addition, the heat protection layer is not gas-permeable, which is why in this system no cooling air film can be formed on the highly stressed inside of the heat protection layer.

J. Kimmel, J. Price et al. Proceedings of ASME Turbo Expo 2003 Power for Land, Sea and Air, GT 2003-38920, June 2003 , vividly describes the test methods for combustion chamber linings. For example, combustor liners for gas turbines typically have to have a minimum life of 30,000 hours. Conditions that may occur include 1200 ° C at 10 atm pressure and 1.5 atm vapor pressure of water vapor.

The object of the present invention is thus to provide a combustion chamber lining for gas turbines which, in spite of the lowest possible weight, should have the greatest possible rigidity, the heat and heat resistant layer, if possible, being resistant both to the inside and the outside can be cooled.

The object underlying the invention is achieved in a first embodiment by a combustion chamber lining of gas turbines with a hot gas side facing gas-permeable heat protection layer (1) and one of the heat protection layer (1) by spacer elements (3) separate carrier layer (2).

Compared to the prior art, it is particularly advantageous in combustion chamber linings to carry out the heat protection layer (1) spaced from the carrier layer (2) as a double-layer structure, since the wall thicknesses can be low due to the higher rigidity of this structure, which brings about both a weight saving and a reduction in weight effect more effective cooling of the combustion chamber lining. As a result, additional cooling air can be saved. Due to the high rigidity of the double layer structure, a combustion chamber lining according to the invention is less susceptible to vibration than a single-layer combustion chamber lining. The inventive double-layer combustion chamber lining is cooled, for example, by an impingement diffusion cooling in which the cooling air can first flow through the gas-permeable carrier layer (2) onto the rear wall of the heat protection layer (1), cools the latter and then exit through the gas-permeable heat protection layer (1) and form a cooling air film on the hot gas side of the heat protection layer (1). Due to the double-layered construction, the cooling air mass flow can also be regulated very well, which leads to a great freedom in the design of the gas permeability of the heat protection layer (1) and of the carrier layer (2).

The present invention also eliminates a long biased prejudice. Still in the US 5,291,732 A It is considered particularly disadvantageous to make the heat protection layer (1) gas permeable. Thus, in the cited document in column 1, lines 1 to 41, it is stated that an introduction of cooling air into the combustion chamber would inevitably lead to an increased nitrogen oxide emission. Thus, a solution must be sought to return the cooling air for the cooling of the back of the heat protection layer (1) without increasing the nitrogen oxide emissions in the gas stream (see column 2, lines 22 to 35). So that the cooling air does not enter the combustion chamber, complicatedly shaped outlet devices are provided there, in order to allow the cooling air to escape between the heat protection layer (1) and the carrier layer (2). In contrast, in the present application, the nitrogen oxide emission is reduced by lean combustion. By this lean combustion, however, there is a higher cooling requirement of the heat protection layer (1). Therefore, in the present invention, it is required that this heat protection layer (1) is made gas-permeable, so that it not only cooled on its back, but also on the hot gas facing inside of the heat protection layer (1) can form a cooling air film.

The combustion chamber lining according to the invention may advantageously extend either in one piece over the entire inner surface of the combustion chamber of the turbine to be lined. However, the combustion chamber lining according to the invention can also be designed as a system of shingles. In this case, it is particularly preferred if these shingles in each case at least one twentieth of the inner surface of the combustion chamber space to be covered cover. Advantageously, a single shingle extends over the entire length of the combustion chamber space. However, it may also be particularly advantageous that the shingle extends over the entire circumference of the combustion chamber inside. By compared to the prior art large-scale design of the combustion chamber lining on the one hand, the manufacturing process of the combustion chambers itself is simplified. On the other hand, the combustion chamber lining can be sealed more easily, thus preventing undesired leakage flows of the cooling air into the combustion chamber. Furthermore, the hot gas can penetrate the remaining turbine space at fewer points (for example at the seams) and cause damage.

The distance of the heat protection layer (1) to the carrier layer (2) is advantageously 3 to 30 mm, since in this area the circulation of the cooling air is particularly efficient and yet a particularly high rigidity and thus a low susceptibility to vibration can be achieved.

Preferably, the heat protection layer (1) and / or the carrier layer (2) is perforated with openings (4). As a result, a controlled gas permeability can be effected particularly easily. These openings (4) particularly preferably have diameters in a range of 0.5 to 3 mm. As a result, a sufficiently strong air flow through the carrier layer (2) can be produced, with which the heat protection layer (1) is cooled. Furthermore, through this area of the hole diameter, the air can be discharged into the combustion chamber interior in a particularly efficient manner through the heat protection layer (1) without hot gas being able to penetrate through the heat protection layer (1).

Advantageously, the spacer elements (3) are designed so that they do not affect the freedom of movement of the heat protection layer (1) relative to the carrier layer (2). Therefore, the spacer elements (3) are particularly preferably selected from the group webs, cones, cones, ribs and ridges. Particularly preferably, the distance of the heat protection layer (1) from the carrier layer (2) is 3 to 30 mm. The spacer elements (3) are preferably located on the heat protection layer (1). In addition, no elements complementary to the spacing elements (3), such as grooves or recesses, are found on the respective other layer in order not to limit the freedom of movement of the two layers relative to one another.

It is particularly advantageous if the heat protection layer (1) and / or the carrier layer (2) consist predominantly of fiber-reinforced ceramic, in particular in which the fibers and the matrix material independently of one another consist of materials which are selected from the group aluminasilicates, Mullite, Al ₂ O ₃ , SiO ₂ , SiC, SiBNC, SiCN, C, Si ₃ N ₄ , ZrO ₂ and mixtures thereof. Particularly preferably, the heat protection layer (1) consists of the same material as the carrier layer (2). In particular, the fibers are fibers Nextel ^® from 3M. The matrix material is particularly preferably mullite. At very high temperatures of use> about 1200 ° C heat protection layer, spacers and carrier layer are particularly preferably made of non-oxide ceramic fibers and matrices, such as SiBNC, SiC, SiCN.

Advantageously, the heat protection layer (1) or the carrier layer (2) each independently have a thickness in the range of 1 to 30 mm, in particular in the range of 1 to 6 mm. By these in comparison to the known combustion chamber linings low layer thicknesses, the heat protection layer ( 1) are cooled particularly efficiently.

The openings (4) advantageously have a minimum distance from each other in a range of 2 to 20 mm and / or a maximum distance between them in a range of 40 to 100 mm from each other. As a result, a particularly high mechanical integrity of the combustion chamber lining can be achieved while at the same time providing a particularly uniform cooling effect.

The ratio of the contact surface of the spacer elements (3) with the carrier layer (2) to the total area of the carrier layer (2) is advantageously in a range of 0.01 to 0.3, preferably in the range of 0.1 to 0.2. As a result, a particularly good rigidity can be achieved with a still great cooling effect.

The combustion chamber lining is particularly advantageously formed in one piece. This ensures on the one hand a particularly good material compatibility of the carrier layer (2) with the heat protection layer (1). In addition, the mechanical integrity and the rigidity of the combustion chamber lining and / or the individual combustion chamber shingles are particularly low as a result, and the installation effort in the production of a turbine is particularly low.

If the combustion chamber lining according to the invention is constructed from individual shingles, these are preferably screwed together on the side of the carrier layer (2) facing away from the heat protection layer (1). However, the combustion chamber lining can also be advantageously designed as a single closed ring.

In a further embodiment, the object underlying the invention is achieved by a method for producing a combustion chamber lining according to the invention, characterized in that one produces the carrier layer (2), the spacer element (3) and the heat protection layer (1) either in one piece or the two layers directly together with a ceramic material as a spacer.

The high fracture toughness and good load capacity of modern CMC materials enable the production of complex structures. Particularly with CMCs such as Nextel / Mullit or SiC / SiC materials, it is also possible to join individual components into a complex structure. This allows the inventive method for producing double-layered CMC structures wherein the two combustion chamber linings (support layer (2) and heat protection layer (1)) can be assembled during the manufacturing process, without having to use screws or rivets. For example, a double-layered spacer CMC structure can also be made without a one-step joining by a winding process.

Particularly advantageously, the combustion chamber lining is produced by joining the carrier layer (2) to the heat protection layer (1) if both the fiber material and the matrix material are SiC. In this case, the liquid siliconization process (liquid silicon infiltration, LSI) and a C- and / or SiC-containing joining paste can be used with particular preference, as is known from US Pat DE 19636223 A1 is known or the PIP or LPI method (polymer infiltration and pyrolysis or liquid polymer infiltration) with SiC-forming, polymeric precursors. Furthermore, it is also possible to add gaseous SiC precursors in the CVI process (Chemical Vapor Infiltration).

Advantageously, the carrier layer (2) and the heat protection layer (1) are made in one piece by winding fibers onto a mold, the fibers being coated with a ceramic slurry or ceramic-forming polymeric precursors such as e.g. Poycarbosilanes, polycarbosilazanes, polysiloxanes or MADB / PBS, or carbon-forming, polymeric precursors (for example, phenolic resins) are soaked.

The fibers are advantageously selected from the group of aluminosilicate fibers, mullite fibers, Al ₂ O ₃ fibers, SiO ₂ fibers, SiC fibers, SiBNC fibers, SiCN fibers, Si ₃ N ₄ fibers and ZrO ₂ fibers, particularly preferred however Nextel fibers from the company 3M.

Particular preference is given to using a water-based ceramic slip which comprises materials selected from the group Aluminasilicates, mullite, Al ₂ O ₃ , SiO ₂ , SiC, Si ₃ N ₄ and ZrO ₂ . Of these materials, mullite is particularly preferred. For the construction of a high-temperature resistant, non-oxidic SiC matrix, it is particularly advantageous to use the liquid siliconization process, the PIP or LPI process (polymer infiltration and pyrolysis or liquid polymer infiltration) or the CVI process (chemical vapor infiltration).

Fig. 1 shows a partial cross section of the combustion chamber lining according to the invention.

In this specific embodiment, the heat protection layer (1) is spaced from the carrier layer (2) by spacer elements (3) in the form of ribs or webs. Both the heat protection layer (1) and the carrier layer (2) are perforated with openings (4). In addition, two shingles are connected by screwing (5) in this particular embodiment.

Fig. 2 also shows a partial cross section of the combustion chamber lining according to the invention, in which the material of the heat protection layer (1) and the carrier layer (2) is uniform, so that a separation layer between these two is not present.

Claims (10)

Combustion chamber lining of gas turbines with a gas-permeable heat protection layer (1) facing the hot gas side and a carrier layer (2) separated from the heat protection layer (1) by spacer elements (3). Combustion chamber lining according to claim 1, characterized in that the heat protection layer (1) and / or the carrier layer (2) openings (4), in particular having a diameter in a range of 0.5 to 3 mm. Combustion chamber lining according to claim 1, characterized in that the spacer elements (3) are selected from the group webs, cones, cones, ribs and ridges, in particular the distance of the heat protection layer (1) of the carrier layer (2) is 2 to 30 mm. Combustion chamber lining according to claim 1, characterized in that the heat protection layer (1) and / or the carrier layer (2) consist predominantly independently of fiber-reinforced ceramic, in particular in which the fibers and the matrix material independently of one another consist of materials which are selected from the group Aluminum silicates, yttrium silicates, YAG, mullite, Al ₂ O ₃ , SiO ₂ , SiC, SiBNC, SiCN, C, Si ₃ N ₄ , ZrO _2, and mixtures thereof. Combustion chamber lining according to claim 1, characterized in that the heat protection layer (1) or the carrier layer (2) each independently have a thickness in the range of 1 to 30 mm, in particular in the range of 1 to 6 mm. Combustion chamber lining according to claim 2, characterized in that the openings (4) have a minimum distance in a range of 2 to 20 mm and / or a maximum distance in a range of 40 to 100 mm from each other. Combustion chamber lining according to claim 1, characterized in that the ratio of a contact surface of the spacer elements (3) with the carrier layer (2) to the total area of the carrier layer (2) in a range of 0.001 to 0.3. Combustion lining according to claim 1, characterized in that it is integrally formed. Method for producing a combustion chamber lining according to Claim 1, characterized in that the carrier layer (2), the spacer element and the heat protection layer (1) are either produced in one piece or the two layers are joined directly to a ceramic material as spacer element (3). A method according to claim 9, characterized in that the carrier layer (2), the spacer element and the heat protection layer (1) are made in one piece by winding fibers onto a mold, the fibers being impregnated with a ceramic slurry, a polymeric carbon or polymeric ceramic precursor are.

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