Refractory tile with reinforcing members embedded therein, as liner for gas turbine combustion chamber

The invention relates to a heat shield element, in particular for the internal lining of a combustion chamber or a Furnace. The invention further relates to a combustor having an inner lining formed from heat shield elements and a gas turbine with a combustion chamber.

A thermally and / or thermo-mechanically highly stressed Combustion chamber, such as a furnace, a hot gas duct or a combustion chamber in a gas turbine, in which a hot is medium generated and / or implemented, is to protect against high thermal stress with a corresponding lining provided. The liner is usually made of heat-resistant material and protects a wall of the combustion chamber from direct contact with the hot medium and the associated strong thermal stress.

The US Patent 4,840,131 relates to a fixing ceramic lining elements to a wall of a furnace. Here, a rail system, which is fixed to the wall is. The lining elements have a rectangular shape on with a planar surface and are made of a heat insulating, refractory ceramic fiber material.

The US Patent No. 4,835,831 also deals with the application a refractory lining of a wall of a Furnace, in particular a vertically arranged wall. On the metallic wall of the furnace from a glass, ceramic, or mineral fibers existing layer applied. These Layer by metallic clips or glue on Wall mounted. On this layer is a wire mesh with hexagonal mesh applied. The mesh used also the security against the layer of ceramic fibers falling off. is also secured by a bolt a uniform closed surface of refractory Material applied. Using the method described is largely avoided that incident during spraying refractory particles are thrown back, as with a direct spraying of the refractory particles the metallic wall would be the case.

A ceramic lining of the walls of thermally highly claimed combustion chambers, for example, of gas turbine combustors, is described in EP 0724116 A2. The Lining consists of wall elements made of high-temperature resistant Structural ceramics, such. As silicon carbide (SiC) or silicon nitride (Si₃N₄). The wall elements are mechanically by means of a central fastening bolt resiliently to a metallic supporting structure (wall) fixed to the combustion chamber. Between the wall element and the wall of the combustion chamber there is provided a thick thermal insulation layer, so that the wall element of the wall of the combustion chamber in accordance spaced. The relative to the wall member about three times as thick insulation layer made of ceramic Fiber material which is prefabricated in blocks. The dimensions and the outer shape of the wall elements are at the Geometry of the space to be lined adaptable.

Another type of lining of a thermally highly stressed Combustion chamber is given in EP 0419787 B1. The liner consists of heat shield elements, the mechanically a metallic wall of the combustion chamber are held. The heat shield elements touch the metallic wall directly. In order to avoid excessive heating of the wall, z. B. in consequence of a direct heat transfer from the heat shield element or by penetration of hot medium in the through the mutually adjacent heat shield elements formed Column is provided by the wall of the combustion chamber and the heat shield element applied space formed with cooling and air purge. The sealing air prevents the penetration of hot Medium up to the wall and simultaneously cools the wall and the heat shield element.

WO 99/47874 relates to a wall segment for a combustion chamber and a combustion chamber of a gas turbine. Here is a Wall segment for a combustion chamber, which are called with a Fluid, z. B. a hot gas, can be acted on with a metallic And a supporting structure on the metallic supporting structure mounted heat shield element specified. In between the metallic support structure and the heat shield element is a deformable separating layer is inserted, the possible relative movements absorb the heat shield element and the supporting structure and is intended to compensate. Such relative movements can For example, in the combustor of a gas turbine, in particular an annular combustion chamber, by different thermal expansion the materials used and by pulsations in the combustion chamber, the combustion in an irregular can arise for producing hot working fluid, be caused. At the same time causes the release layer, that the relatively inelastic heat shield element in total-area on the release layer and the metallic supporting structure rests, as the heat shield element partially in the separating layer penetrates. The release layer may as production-related Unevenness on the supporting structure and / or the heat shield element, locally at an inopportune punctual force entry can compensate for lead.

Particularly in the case walls of high temperature gas reactors, such as z. B. from forced-gas turbine combustors, shall have appropriate combustor liners carrying their Structures against a hot gas attack are protected. Ceramic Materials offer this to metallic compared Materials due to their high temperature resistance, Corrosion resistance and low thermal conductivity ideally at.

Because material typical thermal expansion characteristics under the Setting the operation typically occurring temperature differences (Ambient temperature at standstill, maximum Temperature at full load) must heat mobility ceramic ensures heat shields resulted in a temperature-dependent elongation be to ensure that no component-destructive thermal stresses caused by strain restriction. This can be achieved be by the protected before hot gas attack Wall by a variety of in size limited, individual ceramic heat shields, z. B. heat shield elements is of a technical ceramic lined. As already discussed above in connection with EP 0419487 B1, have to between the ceramic heat shield elements appropriate expansion gaps are provided for safety reasons also in the hot state never completely design according may be closed. It has to be ensured that the hot gas does not have the expansion gaps the load-bearing wall structure excessively heated. The easiest and safest way, to avoid this in a gas turbine combustor, is the rinsing of the expansion gaps with air, so-called seal air cooling. For this, the air can be used, the already for the cooling of holding elements for the ceramic Heat shields is required.

The invention has the object of providing a heat shield element indicate that particularly at a high strength have long life. Furthermore, should a particularly low-maintenance combustion chamber and a gas turbine with a such combustion chamber are given.

With respect to the heat shield element, this object is inventively poured solved with a solidified from a ceramic material formed body, in a number is introduced by reinforcing elements.

The invention is based on the consideration that for a particularly long life out blank heat shield element particularly true in the extreme conditions of use should be adapted. To make this possible, and a particularly high number of degrees of freedom for individual adaptation measures provide, among departure from the hitherto conventional production of heat shield elements by pressing now a production by casting is provided. though could produce a molded ceramic heat shield due a relatively little tensile strength in particular in longitudinal and transverse direction of the heat shield element the life be limited the heat shield element. therefore, a system based on a cast base heat shield element to use the thus achievable design Degrees of freedom used in a combustion chamber used to making, should for a long life and an increased passive safety Special measures for structural reinforcement of the base body are made, the particular also the cohesion of the body in case of a possible improve cracking.

In particular, for an increased tensile strength and to reduce of crack lengths, the thermal and thermomechanical could loads occur, therefore reinforcing elements provided that in the body of the heat shield element are integrated. Here these reinforcing elements should be fixed to the heat shield element to the material characteristic of the tensile strength of the reinforcing elements to transfer to the heat shield element. These Function is positioned on the inside of the heat shield elements met reinforcing elements through the ceramic casting material poured into the base body and are thereby connected firmly with this or with the ceramics.

Advantageously, with the use of a casting technique associated constructive freedom in Design of the heat shield elements used in particular for by appropriate geometries or local variations of characteristic material parameters a particularly high load capacity even with changing thermal loads of Heat shield element to ensure.

This adjusted a reinforcing member at the high temperatures is, is exposed to a heat shield element, and They also determined during the casting process with the ceramic casting material connects the respective reinforcing element advantageously formed from a ceramic material, preferably from an oxide ceramic material with a Al₂O₃Content of at least 60 wt .-%, and having a SiO₂-Share of at most 20 wt .-%. This has a relatively high tensile strength and bonds because of the similar ceramic materials in the fixed solidification with the ceramic mold material. In addition, the thermal Elongation of the reinforcing material similar to the rest of ceramic material of the heat shield element, so that when Temperature changes no unfavorable stresses in the heat shield element occur. Further, the reinforcing element expediently of ceramic fibers such as CMC materials or strukturkeramischem manufactured material with a porosity of at most 10% be.

The respective reinforcing element is preferably in the nature a long, extended, round ceramic rod in the form of a Reinforcement executed. To gain element particularly solidly integrated in a heat shield element and to the reinforcing element as stiff as possible be interpreted, has this expediently a number of beads and thickenings on. About this is the reinforcing member in the surrounding Ceramic material anchored, thereby increasing the tensile strength of the Reinforcing element to the entire heat shield element transfers. For rod-shaped configuration, the reinforcing member in particular at its end regions have thickened, thus resulting in a bone shape. By such aufgedickte ends or by rib-like Thickenings is a positive connection between Reinforcement element and base body is ensured. alternative or in addition, this compound can also positively, For example, a sintering process or a grain, be executed.

In order to enhance a heat shield element over the entire area, a reinforcing element expediently also plate-be embodied, in particular, a parallel and a distance from the surface of the heat shield element arranged flat plate may be provided. In this case, each a plate on the working medium side facing be positioned during the cooler side of the heat shield element also assigned to a plate for reinforcement is.

To a solid material as possible bond between one as Plate formed reinforcing member and the surrounding to achieve ceramic material, such a panel advantageously a number of recesses. Thereby can during the pouring of the heat shield element, the ceramic reach casting into the recesses and also there solidify. The plate can, in particular a perforated plate be carried out with the number, size and positioning the holes expediently depending on input end and material parameters are chosen appropriately.

In alternative or additional advantageous embodiment, has a reinforcing member of a heat shield element preferably a grating structure. Thereby, the grating elements a diamond-shaped or square holes structured grid form. A reinforcing member can also be formed by a plate, the circular having recesses from each other at equal intervals are positioned so that a lattice-shaped structure arises.

To solidify a heat shield element particularly on the sides to strengthen or, a reinforcing member is expediently rod-shaped and along a peripheral edge the heat shield element positioned.

To the structural integrity of the heat shield element itself at the onset of cracking over its entire circumference ensure a reinforcing element preferably has an annular closed shape and extends along the periphery the heat shield element.

To the strength of such a ring-shaped reinforcement member and hence that of the heat shield element still increase or to create as rigid, is a Reinforcing element expediently as a circular ring executed.

For stabilization and solidification of the corners of a heat shield element has a reinforcing element advantageously a cruciform shape, wherein the ends in the area of Corners of the heat shield element are positioned. For a appropriate bracing of the cross-shaped reinforcement member in the heat shield elements which increases the tensile strength, can thickens the ends of the cross-shaped reinforcement member be such that the reinforcing member in the heat shield element is anchored.

Conveniently, heat shield elements of the above-described Type components of the inner lining of a combustion chamber. This combustion chamber is advantageously part of a Gas turbine. The combustion chamber may thereby as siloförmige Combustion chamber or as a group of small combustion systems be designed composite combustor, but preferably formed as an annular combustion chamber.

The advantages achieved with the invention consist in particular in the possibility of having recourse to a casting method with the resulting possible design degrees of freedom Heat shield elements establish that a particularly high exhibit tensile strength. By integrating reinforcement elements in heat shield elements, the cast of a consist ceramic material, it is possible that material properties of the reinforcing elements such as in particular to transmit the tensile strength of a heat shield element. The shaping of a heat shield element can be flexible being held. A further advantage is that through the choice of various embodiments of reinforcing elements and the positioning of these in the heat shield element an individual adaptation to the on a heat shield element of thermal and mechanical Strains is made possible. Due to the increased strength the heat shield elements and their service life a heat shield element, because the spread of Cracks and reduces the structural integrity of the component (Passive safety) is increased.

The advantage of a casting process consists in the possibility of more complex forms of heat shield elements produce. So on the one hand the outer basic shape comparatively easily are inexpensive and varied. On the other hand, in a Casting possible devices for attachment the heat shield elements to the combustion chamber wall with pour. Thus, in the cast heat shield elements, for example, Grooves, bores, threads or mounting devices be poured.

An embodiment of the invention is based on a Drawing explained. Therein:<dl tsize="5"><dt>1 shows</dt><dd>a half section through a gas turbine,</dd><dt>FIG 2</dt><dd>the combustor of the gas turbine of FIG 1, </dd><dt>FIG 3</dt><dd>a heat shield element with plate-like reinforcing elements,</dd><dt>FIG 4</dt><dd>a heat shield element with a latticed Reinforcing element,</dd><dt>FIG 5</dt><dd>a heat shield element with bar-shaped reinforcing elements,</dd><dt>FIG 6</dt><dd>a heat shield element with an annular reinforcing element, and</dd><dt>FIG 7</dt><dd>a heat shield element with a cross-shaped reinforcement member.</dd></dl>

The same parts in all figures with the same reference numerals provided.

The gas turbine 1 according to FIG 1 has a compressor 2 for Combustion air, a combustion chamber 4 and a turbine 6 for Driving the compressor 2 and a generator, not shown, or a working machine on. These are the turbine 6 and the compressor 2 to a common, or turbine rotor designated turbine shaft 8, with the the generator or the working machine is connected, and which is rotatably mounted about its central axis. 9 In the the nature of an annular combustion chamber 4 is executed with a number of burners 10 for combustion of a liquid or gaseous fuel equipped.

The turbine 6 comprises a number of the turbine shaft 8 associated rotatable blades 12. The blades 12 are arranged in a ring shape on the turbine shaft 8 and thus form a number of blade rows. furthermore includes the turbine 6, a number of fixed vanes 14, which is also a ring with the formation of fixed guide vane to an inner housing 16 of the turbine 6 are. The blades 12 serve to drive the turbine shaft 8 by momentum transfer from the turbine 6 by flowing working medium M. serve the vanes 14 however, the flow of the working medium M between seen two in the direction of flow of the working medium M successive blade rows or moving blade rings. A successive pair of a ring of Vanes 14 or a guide and a Ring of moving blades 12 or a blade row is also called a turbine stage.

Each vane 14 has a designated as a blade root Platform 18 on which to fix the respective vane 14 on the inner casing 16 of the turbine 6 as a wall element is arranged. The platform 18 is a thermally comparatively heavily loaded component, the outer boundary a heating gas for the turbine 6 by flowing Working medium M forms. Each blade 12 is in an analogous Way through a designated also as a blade platform 20 attached to the turbine shaft eighth

Between the spaced spaced platforms 18 of the vanes 14 of two adjacent rows of vanes is a respective guide ring 21 on the inner housing 16 of the Turbine 6 disposed. The outer surface of each guide ring 21 is also the hot, the turbine 6 by flowing suspended working medium M and in the radial direction from the outer end 22 of opposite him lying blade 12 spaced by a gap. The between adjacent Guide vane arranged guide rings 21 serve in particular as cover elements, the inner wall of the 16 or other housing-mounting hardware from thermal Overuse by the turbine 6 by flowing hot Working medium M protects.

The combustion chamber 4 is in the exemplary embodiment as shown in FIG 2 shown, configured as a so-called annular combustion chamber, wherein a plurality of circumferentially around the turbine shaft 8 around arranged burners 10 in a common Combustion chamber space. For this purpose, the combustion chamber 4 is in its Totality designed as an annular structure which the Turbine shaft 8 is positioned.

is to achieve a relatively high efficiency, the combustion chamber 4 for a relatively high temperature the working medium M of approximately 1200 ° C to 1500 ° C. To even with these unfavorable for the materials operating parameters To allow a relatively long operating time, the combustion chamber wall 24 on its side facing the working medium M-facing side with a from heat shield elements 26 inner lining formed provided. Due to the high temperatures inside the combustion chamber 4, for heat shield elements 26, a cooling system is provided.

The heat shield elements 26 are particularly suitable for a long designed service life, so that as little damage by extreme influences, such as high temperature and vibration the combustion chamber 4, occur. These are these of a formed from a molded ceramic material Base body 28, integrated with the reinforcing elements 30 are. For a suitable temperature resistance of the reinforcing elements these consist of a ceramic material or composite material. The reinforcing elements 30 can to for acting on a heat shield element 26 influences be interpreted. In the figures 3 to 7 different Embodiments of heat shield elements 26 with reinforcing elements 30 listed.

In FIG 3 is a heat shield element 26 with plate-shaped Reinforcing elements 30 is shown, in each case for the the working medium M and the cooled side facing Surface a reinforcing element 30 is provided. In FIG 4 is can be seen that the plate-shaped reinforcing elements 30 for a better bond with the surrounding ceramic can be provided with a lattice-like structure are carried out or as a grid, in particular as a cross grating (FIG 4) or as a perforated grid (FIG 4b).

For a particularly high gain of the edge regions of a Heat shield element 26, as illustrated in FIG 5, rod-shaped reinforcing members 30 are used, the extend along the side edges of a heat shield element 26 and with beads or thickened (FIG 5a) or compressed Ends (FIG 5b) are provided to a fixed anchorage ensure in the surrounding ceramic 28th Out Figure 6 is seen that for a gain of a heat shield element 26 along its circumference, an annular Structure (FIG 6a) of the reinforcing members 30 are used can, with this rigid in a particularly Execution circular (FIG 6b) may be performed. In which, in 7 shows the heat shield element 26 is shown for a stabilizing acting bracing of the corners of a heat shield element 26 a cross-shaped reinforcement member 30 is provided, that at each of its ends for anchoring thickenings comprising the ceramic material 26th