Power plants – Combustion products used as motive fluid – Having mounting or supporting structure
Reexamination Certificate
2002-06-27
2004-01-13
Freay, Charles G. (Department: 3746)
Power plants
Combustion products used as motive fluid
Having mounting or supporting structure
C060S800000, C060S755000, C431S243000, C431S353000
Reexamination Certificate
active
06675586
ABSTRACT:
The present application hereby claims priority under 35 U.S.C. Section 119 on European Patent application number 01115512.4 filed Jun. 27, 2001, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The invention generally relates to a heat shield arrangement for a component carrying hot gas. In particular, it relates to a heat shield arrangement for structural parts of gas turbines, such as, for example, a hot-gas space or a combustion chamber.
2. Background of the Invention
The arrangement includes a plurality of heat shield elements which are arranged next to one another, so as to cover the area, on a carrying structure and which are anchored to the latter.
On account of the high temperatures prevailing in hot-gas spaces, there is a need to protect a wall structure which is exposed to hot gas. For this purpose, it is possible, for example, to line the hot-gas space with heat shield elements, of which the surface facing the hot gas is cooled on the rear side.
EP 0 224 817 B1 describes a heat shield arrangement, in particular for structural parts of gas turbine plants, which is formed from a number of triangular heat shield elements. The heat shield elements are arranged next to one another on a carrying structure, so as to leave a gap in each case, and are screwed to the carrying structure.
One disadvantage of this is that hot gas from the combustion space can pass through the above-described gaps and come into contact with the carrying structure, so that the material of the carrying structure may be damaged as a result of the severe action of heat occurring during operation.
DE-U-29714742.0 illustrates a heat shield component with cooling-fluid pressure routing and a heat shield arrangement for a component carrying hot gas. The heat shield component consists of a hollow arrangement with an outer shell and a small hollow insert. Between the insert and the outer shell there is an interspace, through which the cooling fluid is capable of flowing. The insert possesses, on the bottom side, passage orifices for the cooling fluid. Closed cooling-fluid routing is achieved in that the cooling fluid flows through ducts in the carrying structure into the insert, flows from there through passage orifices into the outer shell, cooling at the same time taking place by impact cooling and convection cooling, and flows back from there through separate outlet ducts in the carrying structure. The multishell construction of the heat shield element ensures closed cooling-fluid routing. However, a multishell construction of this type is highly complicated.
SUMMARY OF THE INVENTION
An object of an embodiment of the invention includes specifying a heat shield arrangement for a structure carrying hot gas. Preferably, the structure can include a metallic structural part of a gas turbine plant or combustion chamber, with heat shield elements anchored next to one another, so as to cover the area, on a carrying structure. In particular, the heat shield arrangement overcomes the disadvantages described, can be used in a flexible way, can easily be produced and can be configured in a simple way in terms of design.
An object may be achieved, according to an embodiment of the invention, by a heat shield arrangement for a structure carrying hot gas, in particular a metallic structural part of a gas turbine plant or combustion chamber, with heat shield elements anchored next to one another, so as to cover the area, on a carrying structure. Preferably, it is formed by at least in each case two adjacent heat shield elements between the carrying structure and in each case the surface of the heat shield elements which faces away from the hot gas, a cooling-air duct, into which cooling air is fed and by which the adjacent heat shield elements communicate with one another.
By virtue of the arrangement according to an embodiment of the invention, it is possible, for example, to implement closed air cooling of a combustion chamber, in that compressor output air is fed into the cooling-air duct formed according to an embodiment of the invention. In the cooling-air duct, the cooling air is collected and, after cooling has taken place, is delivered to the at least one burner, so that it is available for the combustion process.
Advantageously, the at least two adjacent heat shield elements are connected by at least one sealing element, so that the emergence of cooling air from the cooling-air duct into the structure carrying hot gas and/or the entry of hot gas into the cooling-air duct are prevented.
As a result of the thermal movements of the heat shield elements which occur during operation, the latter are usually anchored to the carrying structure so as to leave gaps between the individual heat shield elements, so that the heat shield elements can expand under the action of heat.
The result of leaving gaps between the heat shield elements, however, is that, on the one hand, the cooling air flowing into the cooling-air duct formed according to the invention by at least two adjacent heat shield elements may emerge from the cooling-air duct through at least one gap and enter the combustion chamber, so that this fraction of air (leakage-air stream) is lost for combustion purposes. Furthermore, hot gas may flow in the opposite direction out of the combustion chamber into the cooling-air duct, so that, on the one hand, this hot-gas stream is lost for the purpose of subsequent conversion into mechanical and/or electrical energy and, on the other hand, the cooling potential of the cooling air in the cooling-air duct is reduced, because this cooling air is heated by the leakage streams of hot gas flowing out of the hot-gas space into the cooling-air duct. Consequently, according to an embodiment of the invention, there is provision for the at least two adjacent heat shield elements to be connected by a sealing element. The seal is preferably flexible, so that thermal movements of the heat shield elements do not damage the sealing element.
In an advantageous refinement of the invention, the heat shield elements are designed essentially as plates, in particular as metallic plates, which each have a web in each case at least two opposite edges.
Webs of this type, on the one hand, improve the stability of the heat shield elements, in that they act as stiffening ribs, and, on the other hand, afford a good possibility for mounting the sealing element. Furthermore, the cross section of the cooling-air duct can be set or predetermined by the height of the web, in that the webs of the adjacent heat shield elements form a side wall of the cooling-air duct. Moreover, the stiffening properties of the webs can be fixed by the choice of their geometry, for example of the rib height. In this way, for example, the thermal stresses which occur can be managed effectively.
In an advantageous refinement of the invention, the adjacent heat shield elements are contiguous to one another in each case with one web, and the at least one, in particular U-shaped sealing element can be introduced in each case into a groove of the respective web of the adjacent heat shield elements.
In this refinement of the invention, the mutually contiguous webs of the adjacent heat shield elements point, for example, toward the combustion chamber or preferably toward the carrying structure. The webs each have a groove, in particular a slot in their foot surface, so that the sealing element, which connects the adjacent heat shield elements to one another, can be introduced into the grooves of the webs of the adjacent heat shield elements.
A groove is particularly easy to produce and with the aid of which a connection can be made, in the present exemplary embodiment, between the adjacent heat shield elements. The sealing element is preferably U-shaped, so that, for example, it is flexible under thermal expansion forces acting on the two legs of the U-shaped sealing element and allows these thermal expansion forces, without the sealing element being destroyed. In order to connect the preferably U-shaped sealing element to the adjace
Freay Charles G.
Harness & Dickey & Pierce P.L.C.
Siemens Aktiengesellschaft
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