Hot gas seal

Abstract

An inventive hot gas seal comprises a sealing body and means for allowing a cooling fluid, preferably cooling air, to flow through the interior of the sealing body. Such a hot gas seal can be effectively cooled by guiding a cooling fluid through the interior of the sealing body.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a hot gas seal and a hot gas seal assembly.

BACKGROUND OF INVENTION

[0002] Walls of high temperature gas reactors, e.g. the walls of turbine combustion chambers, need to be shielded by a suitable thermal shield against attack of the hot gas. The thermal shielding can be achieved by providing a hot gas resistant liner, which usually comprises a number of shield elements covering the wall to be shielded. The heat shield elements can e.g. be implemented in form of ceramic heat shield elements (CHS elements) or in form of suitable metallic heat shield elements. To allow for thermal expansion when being exposed to the hot gas, the heat shield elements are arranged such that gaps are left between neighboring heat shield elements. In order to prevent hot gas from passing through these gaps from the hot gas side of a heat shield, e.g. to a carrier structure to which the heat shield elements are fixed, gaps would need purging with air to avoid over-heating. This air is costly leakage.

[0003] In EP 1 302 723 A1 it is proposed to seal gaps between heat shield elements with sealing elements to prevent hot gas from passing the gaps. This sealing elements my be cooled.

SUMMARY OF THE INVENTION

[0004] It is an object of the present invention to provide a hot gas seal and a hot gas seal assembly by which the cooling of the hot gas seal can be improved.

[0005] The first object is solved by a hot gas seal as claimed in claim 1, the second object is solved by a hot gas seal assembly as claimed in claim 11.

[0006] An inventive hot gas seal comprises a sealing body and means for allowing a cooling fluid, preferably cooling air, to flow through the interior of the sealing body.

[0007] Such a hot gas seal can be effectively cooled by guiding a cooling fluid through the interior of the sealing body.

[0008] In a first embodiment of the present invention, at least one cooling channel is formed to extend through the interior of the sealing body as said means for allowing a cooling fluid to flow through the interior of the sealing body.

[0009] In the first embodiment, the sealing body may be shaped in a tube like manner such that it comprises a circumferential portion and an interior space surrounded by said circumferential portion which defines a cooling channel for allowing a cooling fluid to flow through the interior of the tube like shaped sealing body.

[0010] In a second embodiment of the inventive hot gas seal, the sealing body is made from a porous material the pores of which are inter-connected so that the pores form said means for allowing a cooling fluid to flow through the interior of the sealing body. Such a porous material allows for an effective distribution of the cooling air in the interior of the sealing body and, therefore, for evenly cooling the hot gas seal.

[0011] In an advantageous development of the second embodiment, the porous material is an elastic porous material. Such a hot gas seal can be fixed between neighboring heat shield elements by spring forces. As the elastic porous material, a ceramic material, metal foam, or a suitable polymer material may be used. The choice of the material to be used may depend on the temperatures of the hot gas which is to be prevented from passing through the gaps between two heat shield elements.

[0012] A hot gas seal assembly according to the invention comprises a hot gas seal which comprises a sealing body in which at least one cooling channel extending through the interior of the sealing body is formed as a means for allowing a cooling fluid to flow through the interior of the sealing body. The inventive hot gas seal assembly further comprises means which are arranged outside of the hot gas seal for channeling a cooling fluid flow, preferably a cooling air flow, at least partly through the cooling channel of the hot gas seal. By providing such means a highly efficient cooling of the hot gas seal of the assembly is possible.

[0013] The means for channeling cooling fluid through the cooling channel may be designed such that a high static pressure is build up in front of them which channels the cooling fluid at least partly through the cooling channel.

[0014] The inventive hot gas seal assembly may further comprise a means arranged outside the hot gas seal for guiding the cooling fluid which has flown through the cooling channel back into the cooling fluid flow. Such a means may be designed such that a high static pressure is build up in front of them which guides the cooling fluid back into the cooling fluid flow.

[0015] As a means for building up high static pressure, a fixing bolt for fixing a heat shield element or any other flow restriction may be used.

[0016] Further features, properties, and advantages of the present invention are described hereinafter with reference to the accompanying drawings, by means of detailed embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 shows a first embodiment of the inventive hot gas seal.

[0018] FIG. 2 shows a modification of the inventive hot gas seal of the first embodiment.

[0019] FIG. 3 shows a further development of the inventive hot gas seal of the first embodiment.

[0020] FIG. 4 shows a second embodiment of the inventive hot gas seal.

[0021] FIG. 5 shows an embodiment of the inventive hot gas seal assembly.

DETAILED DESCRIPTION OF INVENTION

[0022] A first embodiment of the inventive hot gas seal is shown in FIG. 1. The figure shows, in a schematic fashion, a first heat shield element 10 comprising a first front face 12 in which a first grove 14 is arranged and a second heat shield element 16 having a second front face 18 in which a second grove 20 is arranged. The heat shield elements 10, 16 are arranged such that the first front face 12 and the second front face 18 are disposed opposite to each other with the first grove 14 and the second grove 20 forming a space for accommodating an inventive hot gas seal 22, therein.

[0023] The hot gas seal 22 comprises a sealing body 24 which has a tube-like shape. The interior of the sealing body 24 forms a cooling channel 26 for allowing a cooling fluid, which in the present embodiment is cooling air, to flow through the hot gas seal 22. In the present embodiment, the sealing body 24 comprises a ceramic portion 28 as a highly heat resistant portion.

[0024] The hot gas seal 22 is arranged such in the space formed by the first grove 14 and the second grove 20 that the ceramic portion 28 shows towards the hot gas side of the liner, i.e. the sides of the heat shield elements which are disposed to the hot gas.

[0025] Inside the cooling channel 26, an axial flow of cooling air 30 and a convective cooling air flow which originates from the axial flow 30 and flows clockwise and counter-clockwise along the wall of cooling channel towards the center of the ceramic portion 28 (indicated by arrows) are provided. At the center of the ceramic portion 28, the convective cooling air flow is directed back towards the axial cooling air flow 30. With the described hot gas seal, an effective cooling of the ceramic portion, which is disposed to the hot gas, is possible.

[0026] A modification of the first embodiment is shown in FIG. 2. Again, a hot gas seal 122 is arranged in a space formed by groves 114 and 120 which are arranged in first and second front faces 112 and 118 of first and second heat shield elements 110, 116, respectively. The modification differs from the first embodiment in the cross-sectional shape of the groves 114, 120, the hot gas seal 122, and the cooling channel 126. As shown in FIG. 2, the cross-sectional shape of the sealing body 124 and the cooling channel 126 is chosen to be heart like with the ceramic portion 128 lying opposite to an apex like portion 123 and being indented at its center part towards said apex like portion 123.

[0027] In the modification shown in FIG. 2, the axial cooling air flow 130 takes place close to the apex like portion 123 of the cross-section of the cooling channel. Like in FIG. 1, a clockwise and a counter-clockwise convective cooling air flow (indicated by arrows) takes place along the inner walls of the sealing body 124. However, compared to the cross-sectional shape of the cooling channel in FIG. 1, the re-direction of the convective cooling air flow towards the axial cooling air flow 130 is improved.

[0028] A further development of the first embodiment is shown in FIG. 3. FIG. 3 shows a hot gas seal 222 comprising a sealing body 224 which forms a tube with the interior of the tube forming a cooling channel 226 for allowing cooling air to flow through the hot gas seal 222. In difference to the hot gas seals shown in FIGS. 1 and 2, the hot gas seal of FIG. 3 does not comprise a ceramic portion. Instead, it comprises ceramic or metallic balls 228 or a ceramic or metallic powder which are/is arranged in an elastic matrix 224 which forms the sealing body. In the hot gas seal 222 shown in FIG. 3, due to the ceramic or metallic balls 228 or the ceramic or metallic powder, the sealing body is elastic and shows a good sealing ability.

[0029] A second embodiment of the present invention is shown in FIG. 4. In FIG. 4, a first heat shield element 310, a second heat shield element 312 and a hot gas seal 322 are shown in a schematic fashion. The first heat shield element 310 and the second heat shield element 318 comprise a first front face 312 and a second front face 316, respectively. They further comprise a first hot gas side 313 and a second hot gas side 317.

[0030] In the second liner 318, a recess 320 is formed in the second front face 316 at the edge to the hot gas side 317. The heat shield elements 310, 318 are arranged such that the front faces 312, 316 are disposed opposite to each other and that the recess 320 forms, together with the first front face 312, a space for a accommodating therein the hot gas seal 322 according to the second embodiment.

[0031] Through the gap 331 between the first front face 312 and the second front face 316, a cooling air flow 332 outgoing from a carrier structure flows towards the hot gas side of the liner.

[0032] The sealing body 324 of the hot gas seal 322 is made from a porous material the pores of which are interconnected such that they form channels through which the cooling air of the cooling air flow 332 can pass through the hot gas seal. Thus, the cooling air can flow through the hot gas seal 322.

[0033] In addition, the material of the sealing body 324 is an elastic material, so that the hot gas seal 322 is held in place by spring forces which act on the first front face 312 and the part of the recess 320 which lies opposite to the first front face 312. As elastic material, all materials which are suitable for being disposed to a hot gas can be used. Examples for such materials are porous ceramics, like abradable TBC, metal foams or polymeric materials.

[0034] An embodiment for an inventive hot gas seal assembly 400 is shown in FIG. 5. The figure shows, in a schematic fashion, a heat shield element 410 which is fixed by means of hooks (not shown) and fixing bolts 434, 436 of a generally cylindrical cross section. The fixing bolts 434, 436 are arranged in front of and behind a hot gas seal 422, e.g. a hot gas seal as described with respect to FIG. 3. Due to the high static pressure built up in front of the fixing bolt 434, the cooling air 432 is partly guided into the cooling channel of the hot gas seal 422. After passing through the hot gas seal 422, the cooling air is guided back into the cooling air flow 432 by a low static pressure built up in behind of the fixing bolt 436.

[0035] Although in the shown embodiment for the hot gas seal assembly the fixing bolts 434, 436 are used to build up high and low static pressure, other means could be used as well as long as they allow for building up a high pressure in front of and a low pressure behind the hot gas seal 422.

Claims

What is claimed is:

1. A hot gas seal comprising a sealing body and means for allowing a cooling fluid to flow through the interior of the sealing body.

2. The hot gas seal claimed in claim 1, in which at least one cooling channel extending through the interior of the sealing body is formed as said means for allowing a cooling fluid to flow through the interior of the sealing body.

3. A hot gas seal which comprises a sealing body, the sealing body being shaped in a tube like manner such that it comprises a generally circumferential portion and an interior space surrounded by the circumferential portion which defines a cooling channel for allowing a cooling fluid to flow through the interior of the tube like shaped sealing body.

4. The hot gas seal as claimed in claim 1, in which the sealing body is made from a porous material the pores of which are interconnected so that they form said means for allowing a cooling fluid to flow through the interior of the sealing body.

5. The hot gas seal as claimed in claim 4, in which the porous material is an elastic material.

6. The hot gas seal as claimed in claim 5, in which the elastic material is a ceramic material.

7. The hot gas seal as claimed in claim 5, in which the elastic material is a metal foam.

8. The hot gas seal as claimed in claim 5, in which the elastic porous material is a polymer material.

9. A hot gas seal assembly comprising a hot gas seal which comprises a sealing body in which at least one cooling channel extending through the interior of the sealing body is formed as a means for allowing a cooling fluid to flow through the interior of the sealing body and which further comprises means arranged outside of the hot gas seal for channeling a cooling fluid flow at least partly through the cooling channel of the hot gas seal.

10. The hot gas seal assembly claimed in claim 9, in which the means for channeling the cooling fluid through the cooling channel are designed such that a high static pressure is built up in front of them which channels the cooling fluid at least partly through the cooling channel.

11. The hot gas seal assembly claimed in claim 10, in which a fixing bolt for fixing a heat shield element is used for building up said high static pressure.

12. The hot gas seal assembly claimed in claim 9, comprising a means arranged outside of the hot gas seal for guiding the cooling fluid which has flown through the cooling channel back into the cooling fluid flow.

13. The hot gas seal assembly claimed in claim 12, in which the mans for guiding the cooling fluid back into the cooling fluid flow are designed such that a high static pressure is built up in front of them which guides the cooling fluid back into the cooling fluid flow.

14. The hot gas seal assembly claimed in claim 13, in which a fixing bolt for fixing a heat shield element is used for building up said high static pressure.