EP1288601B1 - Heat shield brick and its use in a combustion chamber - Google Patents

Description

The invention relates to a heat shield brick, in particular for lining a combustion chamber wall, consisting of a base material and a hot medium exposable hot side, a hot side opposite wall side and adjacent to the hot side and the wall side peripheral side. The invention further relates to the use of a heat shield block, in particular for lining a combustion chamber wall.

A thermally and / or thermomechanically highly loaded combustion chamber, such as a kiln, a hot gas duct or a combustion chamber of a gas turbine, in which a hot medium is generated and / or guided, is provided to protect against excessive thermal stress with a corresponding lining. The lining 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 high thermal load.

The prior EP-A-1 191 285 discloses a heat shield brick in which a tension member biased in the circumferential direction is provided so that compressive stresses normal to the peripheral side surface are generated.

U.S. Patent 4,840,131 relates to attachment of ceramic lining elements to a wall of a furnace. Here, a rail system, which is fixed to the wall and having a plurality of ceramic rail elements, is provided. Through the rail system, the lining elements can be mounted on the wall. Between a lining element and the wall of the furnace further ceramic layers may be provided, including a layer of loose, partially compressed ceramic fibers, this layer having at least about the same thickness as the ceramic lining elements or a greater thickness. The lining elements in this case have a rectangular shape with a planar surface and consist of a heat-insulating, refractory ceramic fiber material.

U.S. Patent 4,835,831 also deals with the application of a refractory lining to a wall of a furnace, particularly on a vertically disposed wall. On the metallic wall of the furnace, a layer consisting of glass, ceramic or mineral fibers is applied. This layer is attached to the wall by means of metal clips or glue. On this layer, a wire mesh net with honeycomb mesh is applied. The mesh also serves to secure the layer of ceramic fibers against falling. A uniform closed surface of refractory material is applied to the layer thus secured by means of a suitable spraying process. With the method described is largely avoided that incident during the spraying refractory particles are thrown back, as would be the case with a direct spraying of the refractory particles on the metallic wall.

A ceramic lining of the walls of thermally highly stressed combustion chambers, for example of gas turbine combustion chambers, is described in EP 0 724 116 A2. The lining consists of wall elements of high-temperature-resistant structural ceramics, such as silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ). The wall elements are mechanically fixed by means of a central fastening bolt to a metallic support structure (wall) of the combustion chamber. Between the wall element and the wall of the combustion chamber, a thick thermal insulation layer is provided, so that the wall element is spaced from the wall of the combustion chamber accordingly. About three times as thick in relation to the wall element insulation layer consists of a ceramic fiber material, which is prefabricated in blocks. The dimensions and the external shape of the wall elements are adaptable to the geometry of the space to be lined.

Another type of lining of a thermally highly loaded combustion chamber is given in EP 0 419 487 B1. The lining consists of heat shield elements, which are mechanically supported on a metallic wall of the combustion chamber. The heat shield elements touch the metallic wall directly. To avoid excessive heating of the wall, e.g. As a result of a direct heat transfer from the heat shield element or by introducing hot medium into the gaps formed by the adjacent heat shield elements, the space formed by the wall of the combustion chamber and the heat shield element is supplied with cooling air, the so-called barrier air. The blocking air prevents the penetration of hot medium up to the wall and at the same time 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, a wall segment for a combustion chamber, which is acted upon by a hot fluid, for example a hot gas, indicated with a metallic support structure and a mounted on the metallic support structure heat protection element. Between the metallic support structure and the heat protection element, a deformable separation layer is inserted, which is intended to absorb and largely compensate for possible relative movements of the heat protection element and the support structure. Such relative movements can be caused, for example, in the combustion chamber of a gas turbine, in particular an annular combustion chamber, by different thermal expansion behavior of the materials used or by pulsations in the combustion chamber, as may occur in an irregular combustion to produce the hot working medium or by resonance effects. At the same time, the separating layer causes the relatively inelastic heat protection element to lie overall flat on the separating layer and the metallic support structure, since the heat protection element partially penetrates into the separating layer. The release layer can thus production due to bumps the support structure and / or the heat protection element, which can lead locally to an unfavorable force input compensate.

The invention is based on the observation that, in particular ceramic, heat shield bricks are often insufficiently secured against mechanical stresses such as shock or vibration due to their necessary flexibility in terms of thermal expansions.

The invention is therefore an object of the invention to provide a heat shield block, which ensures high reliability both in terms of unlimited thermal expansion as well as in terms of stability to mechanical, especially shock-like, loads. Another object of the invention is to specify a use of the heat shield block, in particular for lining a combustion chamber wall.

The object directed to a heat shield brick is achieved according to the invention by a heat shield brick, in particular for lining a combustion chamber wall consisting of a base material and a hot medium exposable hot side, a hot side opposite wall side and adjacent to the hot side and the wall side peripheral side, wherein at Circumference side is attached to a prestressing prestressable tension member having a coefficient of thermal expansion, wherein the coefficient of thermal expansion of the base material of the heat shield block is greater than the thermal expansion coefficient of the tension element, so that the bias of the tension element, a leaching of a fragment formed during a fracture is prevented.

With the invention, a completely new way is shown to secure heat shield stones against high accelerations due to shock or vibration permanently. The invention is already based on the knowledge that heat shield bricks, as they are usually used for lining a combustion chamber wall, are excited by stationary and / or transient vibrations in the combustion chamber wall to corresponding vibrations. It can, in particular in a resonance case, significant accelerations occur above a limit acceleration, the heat shield stones stand out from the combustion chamber wall and open again in the episode. Such an impact on the massive or partially damped combustion chamber wall leads to very high forces on the heat shield stones and can lead to significant damage, such as breakage on these. In addition, there is the extremely high thermal load of the heat shield stone due to the application of the heat shield stone with a hot medium during operation. Thus, cracks can occur both on the wall side and on the hot side of the heat shield block, with the risk of dislodgement of material from the heat shield brick as the crack growth increases during further operation. This leads to a significant reduction in the durability of a heat shield stone, especially because such cracks can lead to a material tear and thus to a breakage and complete failure of the entire heat shield stone. As a result, there is an acute danger that debris may enter the combustion chamber and massively damage other components of the combustion chamber or, for example, when used in the gas turbine, the sensitive blade area with turbine blades.

With the proposed heat shield brick with a biased on the peripheral side to a bias tension element, an extremely efficient and long-term stable fuse for a heat shield brick is specified for the first time. Here, the tension element is advantageously biased in the circumferential direction to a bias voltage, wherein a corresponding compressive stress is generated in the interior of the heat shield block, which staples the stone together. Thus, the heat shield brick is held by the tension member under pressure bias, so that acting on the heat shield brick bending tensile forces and crack growth is slowed down. By this compressive stress, which is at least partially directed toward the interior of the heat shield brick, the heat shield brick is already at a comparatively low bias of the Secure tension element. As a result, a possible material tear, for example due to a shock load or a thermal load, effectively counteracted. Existing material cracks can not develop or expand to a limited extent along the hot side of the heat shield brick with appropriate geometric design and arrangement of the tension element. The tension element holds the heat shield brick together, as it were, and secures it, on the one hand, against material cracks and, on the other hand, above all against a complete material tear. In addition to this primary backup function, the risk of leaching or falling out of smaller or larger fragments in the event of a possible material tear or breakage is additionally effectively counteracted. The compressive stress caused by the prestressing of the tension element prevents a detachment of a fragment formed during a fracture.

Of particular advantage is an increase in the passive safety of the heat shield block over the conventional designs. A material tearing or -durchriss is counteracted by the prestressed tension element, wherein in the case of breakdown, a dissolution of a fragment of the heat shield stone is prevented.

The design of the heat shield block with the tension element further results in the advantage of easy prefabrication and easy mounting of the heat shield block, for example for mounting in a combustion chamber. The tension element is simply mounted on the peripheral side and biased in the circumferential direction as required, with a predetermined tension is impressed on the tension element. During assembly, the tension element but also not be biased (bias equal to zero); the bias occurs during operation at high temperature and that by the different thermal expansion coefficients of tension element and stone. This high flexibility on the one hand and the achievable durability the heat shield stone on the other hand are also in view of economic aspects of particular advantage. In particular, inspection or maintenance intervals for the heat shield brick, for example when used in a combustion chamber of a gas turbine, be extended. In the event of a break of the heat shield stone, the operation for the revision of the plant does not have to be set immediately because, due to the increased passive safety, further operation is possible up to the regular inspection interval and even beyond. The heat shield brick is therefore characterized by special emergency running properties.

In a particularly preferred embodiment, the tension element is stress-free at a normal temperature and at an application temperature above the normal temperature, the tension element is under the bias. The tension element is advantageously dimensioned so that a specifically provided mismatch of the thermal expansion coefficients between the heat shield brick and tension element is used in operation, i. at an application temperature of up to 1200 ° C of the impinging on the hot side of the heat shield stone hot medium, apply a sufficiently large, mediated by the bias of the tension element compressive stress on the heat shield stone. At the same time, however, this preload is set so low that it does not lead to creep deformation and relaxation of the tension element or even to the size of the maximum permissible prestressing of the tension element. The normal temperature at which the tension member is de-energized, it is advantageously room temperature, ie about 20 ° C, which allows a particularly simple attachment of the tension member to the peripheral side of the heat shield brick during assembly.

Preferably, the bias is directed in the circumferential direction, ie, the bias voltage has at least one component in the circumferential direction of the heat shield brick. The circumferential direction is substantially perpendicular to the surface normal the hot side or the wall side. As a result, any fragments of the heat shield block are compressed by a corresponding compressive stress in the circumferential direction. Dissolution of the fragments in the direction of the surface normal of the hot side is prevented due to a wedging effect of the fragments.

In a preferred embodiment, the peripheral side has a circumferential groove, in which engages the tension element. The circumferential groove is configured such that it largely integrates the tension element in the heat shield brick.

In general, heat shield bricks are secured in the circumferential direction by two so-called stone holder pairs, so that when broken in the circumferential direction of each fragment is held only by a respective stone holder pair. The stone holder pairs are arranged on the peripheral side of the heat shield brick on opposite sides and define a first axis of the heat shield brick. Along a second axis, which is directed perpendicular to the first axis and generally coincides with the flow direction of the hot medium along the hot side of the heat shield brick, the heat shield brick on the peripheral side of the tension member receiving circumferential groove. The opposite sides of the peripheral side along the second axis are also referred to as end faces of the heat shield brick. Each end face may have a respective circumferential groove in which a respective tension element engages, which is under pretension during operation. For a particularly advantageous and secure engagement of the tension element in the circumferential groove, this can be additionally provided with holes, for example blind holes, at each end of the circumferential groove. In this way, the tension element can be concealed and thus used, so to speak, fully integrated in the heat shield block or inserted and is advantageously not directly exposed thereby possibly inflowing hot gas. To avoid mechanical or thermomechanical voltage increases is the Circumferential and possibly the additional holes designed rounded.

Preferably, the peripheral side has a peripheral side surface, wherein the tension element engages in the circumferential groove in such a way that the tension element is recessed against the peripheral side surface or terminates flush therewith. The tension element can in this case be constructed in various ways and designed so that a favorable combination of low-tension design and cost-effective production is achieved. The cross section of the tension element can be designed both rectangular and round or oval. Advantageously, sharp corners or edges are produced here neither on the tension element nor on the circumferential groove or possibly the additional holes in the heat shield block.

In a particularly simple and preferred geometric configuration, the tension element comprises a web, at the axial ends of each of which a substantially perpendicular to the web extending finger-shaped anchor is provided. The web and armature in this case essentially have the same shape and cross section. After attaching the tension member to the peripheral side of the heat shield stone, the finger-shaped anchors protrude into respective holes in the heat shield brick, wherein the web engages in the circumferential groove. Advantageously, in this case, the web terminates flush with the peripheral side surface, wherein a certain clearance between the tension member and the circumferential groove is provided, so that a generally occurring in operation thermal warping of the heat shield brick in the direction of the surface normal of the hot side is tolerated.

The tension element preferably consists of a ceramic material, in particular of a Si ₃ N ₄ base ceramic. This high-temperature, creep and corrosion-resistant base ceramic, developed especially for high-temperature applications under a gas turbine atmosphere, appears to be due to the expected high operating temperatures of typically about 1000 ° C, but sometimes up to 1200 ° C for use as a tension element particularly suitable. The tension element can be made of a full ceramic, which can be wrapped on the finger-shaped anchors with which the tension element engages in the interior of the heat shield block, additionally with elastic fiber-ceramic material. As a result, a particularly strong and durable anchoring of the tension element in the heat shield stone is reached.

Preferably, the tension element is attached by means of an adhesive. The tension element is at least partially bonded to the heat shield brick, wherein the adhesive bond between the tension member and heat shield brick is preferably provided in the region of the finger-shaped armature. By bonding additional securing of the tension element is achieved with respect to a possible leaching and increases the durability in accordance with. When gluing the tension element with the heat shield brick, both a conventional adhesive and a high temperature resistant adhesive can be used. Also, silicate-based adhesives can be used which have excellent adhesive properties and high temperature resistance. Particularly advantageous in the adhesive connection proves the use of a ceramic material for the tension element.

In a particularly preferred embodiment, the tension element has a channel into which the adhesive for anchoring the tension element can be introduced.

For this purpose, the tension element may for example be made of a so-called ceramic tube material, whereby a channel or a corresponding plurality of channels for the tension element can be realized.

In an embodiment of the tension element with a web of which at a respective axial end perpendicular to the web branched finger-shaped anchor, the finger-shaped anchors are preferably provided over the entire axial extent of the finger-shaped armature and the entire circumference of the armature with openings. In addition, a filling opening is provided via which the adhesive can be introduced into the channel. After inserting the tension member into the heat shield brick, the adhesive is injected through the filler opening into the channel or plurality of channels and emerges from the openings of the finger-shaped anchors. After setting of the adhesive, a large-area and firm bond between the heat shield brick and the tension element in the region of the finger-shaped anchors can be achieved.

Preferably, a further tension element is provided, which is attached to the peripheral side and opposite to the tension element.

In this case, the tension element and the further tension element is advantageously attached to a respective end face of the heat shield block, whereby crack growth or breakage of the heat shield block in the flow direction of the hot gas is avoided.

The heat shield block preferably consists of a ceramic base material, in particular of a refractory ceramic. The choice of a ceramic as a base material for the heat shield stone, the use of the heat shield brick is guaranteed up to very high temperatures, at the same time oxidative and / or corrosive attacks, such as when exposed to the hot side of the heat shield stone with a hot medium, eg a hot gas, occur, are largely harmless to the heat shield stone. Advantageously, the tension element is easily connectable to the ceramic base material of the heat shield block. The fixed connection can also be designed as a detachable connection, as already mentioned above. In addition come in addition to a bonding and the attachment of the tension element by means of suitable fasteners on the peripheral side, for example by a suitable clamping or by a screw. By choosing a tension element, which, however, at least partially consists of a ceramic material, a good adaptation to the ceramic base material of the heat shield brick is achieved in terms of thermo-mechanical properties. Due to the fixed anchoring of the tension element with the base material of the heat shield block is advantageously designed at least at the high application temperature in a kind of solid composite with the tension element. As a result, a compact construction and structure of the heat shield stone is given, which has an extremely high durability and passive safety even with large thermal and / or mechanical loads. This is of particularly great advantage when using the heat shield brick in a combustion chamber, because even after a crack or material crack the heat shield function of the heat shield brick is still guaranteed, in particular no fragments can get into the combustion chamber.

Economically, this results on the one hand the advantage that in normal operation no extraordinary maintenance and / or revision of the heat shield brick having combustion chamber is required. On the other hand, the heat shield brick in the event of special incidents on emergency running properties, so that consequential damage to a turbine, for example, the blading of the turbine can be avoided. The combustion chamber can be operated at least with the usual maintenance cycles, but also an extension of the service life due to the passive safety increased with the tension element can be achieved.

The object directed to the use of a heat shield stone is achieved according to the invention by the use of a heat shield brick according to the above statements in a combustion chamber of a gas turbine.

The advantages of using the heat shield brick in a combustion chamber, a gas turbine, arise in accordance with the statements on the heat shield brick.

FIG 1 und 2

jeweils eine Seitenansicht eines Hitzeschildsteins mit Zugelement,

FIG 3

eine perspektivische Ansicht eines Hitzeschildsteins in einer Explosionsdarstellung,

FIG 4 und 5

jeweils eine Variante der Verklebung des Hitzeschildsteins mit dem Zugelement,

FIG 6

einen Hitzeschildstein,

FIG 7 und 8

eine jeweilige Ansicht des Zugelements des in FIG 6 gezeigten Hitzeschildsteins,

FIG 9

eine Hitzeschildstein mit einer Variante der geometrischen Ausgestaltung von Umfangsnut und Zugelement.

FIG 10 u. 11

eine jeweilige Detailansicht des in FIG 9 gezeigten Zugelements,

FIG 12

einen Hitzeschildstein mit einer weiteren geometrischen Variante des in die Umfangsnut eingreifenden Zugelements,

FIG 13 u. 14

jeweilige detaillierte Darstellungen des in FIG 12 gezeigten Zugelements.

The invention will be explained in more detail by way of example with reference to the drawing. It shows schematically and partially simplified:

1 and 2

each a side view of a heat shield stone with tension element,

FIG. 3

a perspective view of a heat shield stone in an exploded view,

4 and 5

in each case a variant of the bonding of the heat shield block with the tension element,

FIG. 6

a heat shield stone,

FIGS. 7 and 8

a respective view of the tension element of the heat shield block shown in FIG. 6,

FIG. 9

a heat shield brick with a variant of the geometric configuration of circumferential groove and tension element.

FIG. 10 u. 11

a respective detailed view of the tension element shown in FIG 9,

FIG. 12

a heat shield block with a further geometric variant of the tension element engaging in the circumferential groove,

FIG. 13 u. 14

respective detailed representations of the tension element shown in FIG.

Like reference numerals have the same meaning in the various figures.

FIG. 1 shows a side view of a heat shield block 1. The heat shield block 1 has a hot side 3 and a wall side 5 opposite the hot side 3. On the hot side 3 and the wall side 5 is adjacent to a peripheral side 7 of the heat shield block 1. The peripheral side 7 has a peripheral side surface 9. When using the heat shield block 1, the hot side 3 is acted upon by a hot medium M, for example a hot gas. On the peripheral side 7 of the heat shield block 1, a tension element 11 pretensioned in the circumferential direction 17 is provided. The tension element 11 is biased to a bias voltage F _Z. The peripheral side 7 has a circumferential groove 13 into which the tension element 11 engages. By the bias voltage F _{Z of} the tension element 11, a compressive stress F _{P is} effected on the material of the heat shield block 1, which acts, for example, on a surface element A. The tension element 11 is prestressed such that the compressive stress F _P acts substantially along the circumferential direction 17 towards the center of the heat shield block 1. To generate a bias voltage F _Z in the circumferential direction 17, the tension element 11 has a certain elasticity. By adjusting the material of the tension member 11 and the base material of the heat shield block 1 can be achieved that at a normal temperature, the tension element 11 is free of stress, ie the bias F _Z = 0. The normal temperature is in this case preferably room temperature, that is about 20 ° C. This allows a particularly simple attachment of the tension member 11 on the peripheral side 7 of the heat shield block 1 by the tension element 11 is inserted into the circumferential groove 13. In addition, a certain clearance between the tension member 11 and the circumferential groove 13 is provided in the installed state, which is achieved by the gap 19.

By selective adjustment of the thermal expansion coefficients of the base material of the heat shield block 1 and the Tensile element 11 is achieved that during operation of the heat shield block 1, a sufficiently large bias F _Z on the heat shield stone 1 can be applied. For this purpose, the thermal expansion coefficient of the base material of the heat shield block 1 is selected to be greater than the thermal expansion coefficient of the tension element 11. At an application temperature above the normal temperature, which can be up to 1200 ° C when using the heat shield block 1 in a gas turbine, it is achieved that the tension member 11 is under the bias F _Z. This is brought about by the relative thermal expansion between the base material of the heat shield block 1 and the tension element 11. The tension element 11 is similar to a clip introduced into the heat shield block 1 and causes a centrally directed compressive stress F _P on the heat shield stone 1. By this clamping function of the tension member 11 this is firmly clamped under operating conditions at the application temperature. With the tension element 11 is a significant increase in the passive safety and thus durability of the heat shield block 1 when used in a combustion chamber, for example in the combustion chamber of a gas turbine, achieved. The heat shield brick 1 is largely protected in particular against the risk of crack formation of the crack propagation on the hot side 3, the wall side 5 or the peripheral side 7.

To illustrate this fact, FIG. 2 shows a heat shield block 1 with a tension element 11, wherein a crack 21 extends completely from the hot side 3 to the wall side 5 through the base material of the heat shield block 1. The breakage of the heat shield block 1 has occurred in a central region of the heat shield block 1. Due to the significant thermal or mechanical stress, z. B. by impact on a combustion chamber wall of a gas turbine, not shown, such a crack 21 of the heat shield stone 1 is caused. The crack 21 results in the heat shield brick 1 being divided into a first fragment 57A and a second fragment 57B. By mediated by the tension element 11 Compressive stress F _P on the heat shield brick 1, the fragments 57 A, 57 B along the circumferential direction 17 are pressed against each other. As a result, a detachment of a fragment formed at a fraction 57A, 57B is reliably prevented. On the other hand, without the tension element 11 under prestressing F _Z , there would be an acute risk of detaching a fragment 57A, 57B from the composite in a direction substantially parallel to the surface normal of the hot side 3. The risk that the fragments 57A, 57B would not be shown in detail Combustor reach a gas turbine and other components of a combustion chamber or, for example when used in a gas turbine, damage the sensitive blade area of the turbine blades massively, is effectively counteracted by the provision of the tension element 11. The heat shield block shown in Figure 2 has for attachment of the heat shield brick to a combustion chamber wall, not shown, a mounting groove 15 into which a support member 25A engages. Another support member 25B engages with the attachment groove 15 and is disposed along the circumferential direction 17 opposite to the support member 25A. When installing the heat shield block 1, the wall side 5 faces a corresponding wall, not shown, of the combustion chamber, so that the heat shield block 1 can be fastened elastically to the wall (not shown) via the fastening elements 25A, 25B.

A perspective view in an exploded view of the heat shield block 1 is shown in FIG. The heat shield brick 1 has essentially a cuboid geometry and extends along a flow direction 27 and a circumferential direction 17. The flow direction 27 forms when using the heat shield block 1 in a combustion chamber of a gas turbine preferably at the same time also the direction in which the hot medium M flows and with which the hot side 3 is acted upon (see also Figures 1 and 2). By the fixing groove 15 and the circumferential groove 13, the peripheral side 7 decomposes functionally into different areas 35A, 35B, 37A, 37B, which form portions of the peripheral side 7 adjacent to the hot side 3 and the wall side 5. The partial region of the peripheral side 7 having the fastening groove 15 is referred to as the fastening side 35A, 35B, while the partial region having the tension element 11A, 11B receiving the peripheral groove 13 is referred to as end face 37A, 37B. In the exploded view of FIG 3, two tension members 11A, 11B are shown, which are not used for the sake of clarity in the circumferential groove 13, but are taken out of this. The tension element 11A is assigned to a circumferential groove 13 in the end face 37A, while the tension element 11B is provided on the end face 37B opposite the end face 37A along the flow direction 27. Each of the tension elements 11A, 11B is configured in the shape of a clip and has a web 29 and two finger-shaped anchors 31 each. The finger-shaped armature 31 is arranged at the two longitudinal ends of the web 29 and protrudes substantially perpendicular to the longitudinal extent of the web 29 in the direction of the interior of the heat shield stone 1. Corresponding to the finger-shaped anchors 31, the circumferential groove 13 corresponding to the number of finger-shaped armature 31 holes 33, eg blind holes, on. In each of these holes 33, a finger-shaped anchor 31 for anchoring the tension element 11A, 11B at the respective end face 37A, 37B can be inserted when installing the tension elements 11A, 11B.

A possible substantially central crack 21, by which the heat shield brick is divided into a first fragment 57A and a second fragment 57B, is bridged by the tension elements 11A, 11B. By the tension F _Z applied to the tension element 11A, 11B, as described in connection with the discussion in FIGS. 1 and 2, a detachment of the fragments 57A, 57B is prevented.

For fastening or anchoring the tension elements 11A, 11B, various possibilities are proposed, of which in FIGS. 4 and 5 by way of example two preferred variants are illustrated. In both variants, an adhesion of the finger-shaped armature 31 with the ceramic base material 49 of the heat shield block 1 is provided. In FIG. 4, an adhesive 39 is introduced into the bore 33 before insertion of the finger-shaped armature 31 into the bore 33 for this purpose. For fixing the tension member 11A, 11B, the finger-shaped armature 31 is inserted into the hole 33 provided with the adhesive 39, the finger-shaped armature 31 being pressed into the adhesive 39. After setting of the adhesive 39, for example a ceramic adhesive, a secure and permanent adhesive bond between the finger-shaped armature 31 and the ceramic base material 49 of the heat shield block 1 is achieved. The peripheral side 7 has a peripheral side surface 9, wherein the tension element 11A, 11B, respectively the web 29 of the tension element 11A, 11B engages in the circumferential groove 13 such that the tension element 11A, 11B terminates flush with the peripheral side surface 9. It is also possible that the tension member 11A, 11B is recessed from the peripheral side surface toward the interior of the heat shield brick 1. As a result of this embodiment, the tension element 11A, 11B is concealed and, as it were, integrated into the heat shield block 1 and thus not directly exposed to any hot medium M which may flow in. The proposed game in the form of a gap 19 between the tension member 11A, 11B allows a largely unhindered thermal buckling of the heat shield block 1 in the operating case.

FIG. 5 shows a variant of the bonding of the tension element 11 with the ceramic base material 49 in the region of the bore 33, which variant is alternative to FIG. 4. The tension element 11 has a channel 41 for this purpose. The channel 41 has an inlet opening 43 which, facing away from the circumferential side 7, is provided on the outer surface of the tension element 11 on the web side. The channel 41 branches and opens into a plurality of outlet openings 45 in the finger-shaped armature 31. The tension element 11 with the web 29 and the finger-shaped armature 31 are preferably made of a ceramic material, for example a Si ₃ N ₄ base ceramic. In the present embodiment of FIG 5, the tension member 11 consists of a ceramic tube material. The finger-shaped armature 31 has, for example, over the entire axial extent of the armature 31 and over the entire circumference of the armature 31 distributed outlet openings 45. For bonding the tension element 11 with the material 49 of the heat shield block 1 in the region of the bore 33, adhesive 39, for example a ceramic adhesive, is supplied through the inlet opening 39 to the channel 41. The adhesive 39 is preferably injected into the inlet opening, so that a uniform and complete distribution of the adhesive 39 in the entire channel 41 and a leakage of the adhesive through the outlet opening 45 is possible. A large-area bond between the ceramic material 49 of the heat shield block 1 and the finger-shaped armature 31 is thus achieved. The finger-shaped armature 31 acts in this embodiment as a hollow armature, via which the adhesive 39 can be brought very targeted to the areas to be bonded in the bore 33.

In addition to the use of a ceramic tube material for the tie rod 11 but also the use of a full ceramic is possible, as shown for example in FIG. In addition to the use of an adhesive 39 for bonding, the finger-shaped armature 31, with which the tension element 11 engages in the heat shield stone 1, can be enveloped with the elastic fiber-ceramic material. This enhances the connection and the durability of the adhesive bond between anchor 31 and the ceramic material 49 in the blind bore 33rd

In the following figures 6 to 14 various constructive variants of a mounted on a heat shield stone 1 tension element 11 are shown graphically. In this case, essentially the cross section of the tension element 11 and the tensioning element 11 receiving corresponding circumferential groove 13 is geometrically varied. It is important to ensure that neither on the tension element 11 nor on the circumferential groove 13 sharp corners or Edges exist. For this purpose, rounding 51 on the tension element 11 and correspondingly on the circumferential groove 13 are provided in the critical areas. FIG. 7 and FIG. 8 show two side views of the tension element 11, as it is inserted into the heat shield block 1 according to FIG. The finger-shaped armature 31 extends substantially perpendicularly to the web 29 and has a shank region 53 and an end section 55 adjoining the shank region 53. The end portion 55 is slightly enlarged in cross-section with respect to the shaft portion 53, so that a particularly favorable anchoring of the armature 31 in the bore 33 can be achieved.

FIG 10 and FIG 11 show a tension element 11, as it is attached to a heat shield block 1 according to the embodiment of FIG 9. The cross section of the tension element here is substantially rectangular, but may also be square. Corresponding to the selected geometry, the circumferential groove 13 is designed to provide a gap 19 and a rounded portion 51. Analogous to the exemplary embodiment of FIGS. 6 to 8, the tension element 11 has a finger-shaped armature 31, which comprises a shaft region 53 and an end section 55. In an analogous manner, Figures 12 to 14 show an embodiment of the invention, in which the tension element 11 has a substantially round or oval cross-sectional area.

In all embodiments described above, the attachment of the tension elements to the heat shield block 1 is preferably carried out by means of a bond with an adhesive 39, for example a ceramic adhesive. The bond proves to be particularly favorable for the installation of the heat shield stone 1 in a combustion chamber, where the heat shield bricks are used at a high application temperature. The bonding of the tension element 11 prevents a detachment of the tension element 11 from the heat shield block 1 at a normal temperature below the application temperature, ie when the tension element is preferably free of stress. The bonding can be done be executed so that after curing, a positive connection of the tension member 11 is formed with the heat shield stone 1. As a result, the pulling element can not fall out, even if the hardened adhesive 39 breaks, since any fragments of the cured adhesive would get caught. In an alternative embodiment, a positive connection between tension element 11 and heat shield stone 1 is possible, with an adhesive 39 can be dispensed with entirely. In this case, a certain bias F _Z on the tension element 11 already at a normal temperature, for example room temperature, apply. This bias serves as a holding voltage for secure clamping of the tension member 11 with the heat shield stone 1 during assembly.

The advantages of the heat shield block according to the invention lie in a significant increase in the operational safety when using the heat shield brick in a combustion chamber, for example in a highly thermally stressed combustion chamber of a gas turbine. In particular, machine damage due to breakage or rupture of the heat shield stone - which may occur as a result of thermal and / or mechanical loads of the heat shield stone - avoid with great certainty, since a detachment of a fragment formed during a break is prevented by the tension element. This is accompanied by a significant extension of the service life of the heat shield block, since on the one hand the crack growth is slowed down and on the other hand a larger crack length up to the exchange limit can be permitted. Consequently, a reduction in the number and duration of forced shutdowns of the combustion chamber is possible, which in particular also increases the availability of a system when using the heat shield block for lining a combustion chamber wall.

Claims (11)

1. Heat shield block (1), in particular for lining a combustion chamber wall, consisting of a parent material and a hot side (3) which can be subjected to a hot medium (M), a wall side (5) opposite the hot side (3), and a peripheral side (7) adjoining the hot side (3) and the wall side (5), characterized in that a tension element (11, 11A, 11B), having a coefficient of thermal expansion, which can be prestressed to a prestress (F_Z) is attached to the peripheral side (7), the coefficient of thermal expansion of the parent material of the heat shield block being greater than the coefficient of thermal expansion of the tension element (11, 11A, 11B), so that release of a fragment (57A, 57B) formed during a fracture is prevented by the prestress (F_Z) of the tension element (11, 11A, 11B).
2. Heat shield block (1) according to Claim 1, characterized in that the tension element (11, 11A, 11B) is stress-free at a normal temperature, and in that the tension element (11, 11A, 11B) is under the prestress (F_Z) at an application temperature above the normal temperature.
3. Heat shield block (1) according to Claim 1 or 2, characterized in that the prestress (F_Z) is directed in the peripheral direction (17).
4. Heat shield block (1) according to Claim 1, 2 or 3, characterized in that the peripheral side (7) has a peripheral groove (13), in which the tension element (11, 11A, 11B) engages.
5. Heat shield block (1) according to Claim 4, characterized in that the peripheral side (7) has a peripheral-side surface (9), the tension element (11, 11A, 11B) engaging in the peripheral groove (13) in such a way that the tension element (11, 11A, 11B) is set back from the peripheral-side surface (9) or terminates flush with the latter.
6. Heat shield block (1) according to one of the preceding claims, characterized in that the tension element (11, 11A, 11B) is made of a ceramic material (47), in particular an Si₃N₄-based ceramic.
7. Heat shield block (1) according to one of the preceding claims, characterized in that the tension element (11, 11A, 11B) is fastened by means of an adhesive (39).
8. Heat shield block (1) according to Claim 7, characterized in that the tension element (11, 11A, 11B) has a passage (41) into which the adhesive (39) for anchoring the tension element (11, 11A, 11B) can be introduced.
9. Heat shield block according to one of the preceding claims, characterized in that a further tension element (11B) is provided, this further tension element (11B) being attached to the peripheral side (7) and being opposite the tension element (11A).
10. Heat shield block (1) according to one of the preceding claims, characterized in that it is made of a ceramic parent material (49), in particular a refractory ceramic.
11. Use of a heat shield block (1) according to one of the preceding claims in a combustion chamber of a gas turbine.

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