JPH0581740B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a thermal shielding device for protecting a support structure against hot fluids.

[Prior Art] A plurality of cooling fluid passage holes in a support structure and a lining made of a heat-resistant material, the lining being fixed to the support structure so as to be thermally displaceable leaving a cooling fluid gap. Heat shielding devices for protecting support structures against hot fluids, in particular for protecting hot gas channel walls, such as in gas turbine installations, are assembled from parallel arranged heat shielding elements of e.g. It is known from German Patent No. 1 173 734 as a lining for the inner wall of a combustion chamber of a turbine installation. In this case, the heat shielding element consists of molded bricks which are fixed to the combustion chamber wall using retaining clips made of austenitic material, with the bricks being spaced apart from each other to form cooling air gaps. The retaining clip itself is held by a bolt passing through the combustion chamber wall. In order to be able to adapt the fixing part to the dimensions of the combustion chamber brick, which do not always correspond, the bolt is held adjustably in the combustion chamber wall via an eccentric bush.

[Problems to be Solved by the Invention] It is an object of the present invention to provide an improved heat shielding device of the above type that is suitable for lining structures of complex shapes. The aim here is to keep the cooling air consumption as low as possible and to distribute it as uniformly as possible over the area to be protected, without risking high thermal stresses on the heat shielding element and its fixings. Furthermore, it is an attempt to construct the heat shielding device using only metal structural parts as much as possible.

[Means for Solving the Problem] This object is based on the invention in the above-mentioned heat shielding device, in which each heat shielding element has a mushroom-shaped umbrella part and a handle part, where the umbrella part is straight or straight. A flat or three-dimensional polygonal plate with a curved border, a handle connecting the central area of the plate to the support structure, which is provided between the heat shielding elements. a pedestal edge disposed on the support structure opposite each cooled fluid gap extending in the direction of the gap and across substantially the entire length of the gap;
This is achieved in that the distance between the ridge and the umbrella part is dimensioned in such a way that a defined constriction point for the cooling fluid flow occurs. Advantageous embodiments of the invention are described in the claims 2 to 14.

[Operations and Effects] As will be explained in detail later with reference to the drawings, the present invention has various advantages. The mushroom-like configuration of the individual heat shielding elements allows the umbrella portion of the element to extend freely in all directions away from the handle portion without creating excessive thermal stresses. In some cases, the relatively hot upper surface of the canopy can extend more than its lower surface, which causes the canopy to bulge slightly but without thermal stress. Furthermore, it is possible without any problem to cover any three-dimensional surface of the support structure with such a heat shielding element. Such a surface can always be decomposed into sections of suitable size, and whether the most advantageous solution is a triangle or a polygon or a section of the surface of a rotating body depends on the particularities of the shape. . It is also basically possible to use a three-dimensionally curved umbrella portion. It is particularly advantageous to approximate a given structure surface by triangles that are as flat as possible, the size of the triangles being dependent on the accuracy of the desired approximation. Although the resulting triangles are generally not equilateral and are not mutually congruent, it is desirable to use triangles that are approximately equilateral as much as possible.
Although this may be difficult in individual locations, it is in principle desirable to use triangles with corners that are not too sharp. This is because long tips have a higher tendency to vibrate. Although it is not necessarily necessary to fix the individual heat shielding elements exactly at their center of gravity, this is generally the most advantageous solution. Since the fixing method depends on the respective requirements, various methods are conceivable. The simplest method is to use an anchor bolt that passes through a through hole in the support structure and is tightened to the support structure by at least one fixing nut screwed into its free end. A predetermined spacing between the support structure and the umbrella part is created by suitable means, such as spacing rings or ring-shaped shoulders. However, although such devices can be easily disassembled when the back side of the support structure is accessible, access to the back side is not always possible, for example in the hot gas channels of gas turbines. Another fastening method, as will be explained in more detail later in the drawing, consists in that the heat shielding element is screwed firmly from the hot gas side using anchor bolts with submerged heads. This, of course, requires a correspondingly fastened nut on the back side of the support structure.

A decisive effect of the heat shielding device is achieved by the mode of cooling of the heat shielding element. Cooling fluid, particularly air, is directed towards the underside of the umbrella portion through a number of holes in the support structure. This air hits the surface to be cooled almost perpendicularly and flows out laterally along this surface (so-called impingement cooling). This effect alone significantly cools the umbrella portion. Furthermore, the cooling fluid passes through the gap between the edge of the canopy and the adjacent canopy, but is redirected by the hot fluid flowing over it and additionally onto the top surface of the canopy. Forms a cooling film. Since many of the gaps do not extend in the flow direction, a very uniform and effective cooling film can be formed.

Since the cooling fluid gap between the thermal shielding elements has a variable and varying width in relation to temperature and other parameters, this gap can only serve to a limited extent as a well-defined throttling point for the cooling fluid flow. Not suitable. It is therefore advantageous to arrange a ridge, which forms a defined spacing relative to the umbrella part, on the support structure opposite this gap. This rim may have on its upper surface a recess defined transversely to the direction of extension of the rim, which recess ensures a minimum cooling fluid flow even when the heat shielding element contacts the rim. . Furthermore, the pedestal edge and the heat shielding element are arranged in such a way that they fit into each other closely during initial assembly and may form gaps only at the start of operation as a result of thermal influences.
It may be advantageous to choose both dimensions.

[Examples] Next, the present invention will be described in detail with reference to drawings showing two embodiments of the heat shielding device based on the present invention.

The heat shielding device shown in FIGS. 1 and 2 is particularly suitable for gas turbine installations, and in particular for turbine housings through which hot gases coming from the combustion chamber flow. In the past, it has been difficult to cool such a support structure 1 or to protect it with heat shielding devices. Such support structures have therefore often been used without heat shields, despite the drawbacks. In contrast, according to the invention, the support structure 1 is provided with cooling air passage holes 2, which are arranged uniformly or distributed over the support structure 1 depending on the cooling needs. There is. In order to show the arrangement of the cooling air passage holes 2, one heat shielding element has been removed in FIG. 1 so that the details of the underside of this element can be seen. In Figure 2, the symbol HG
The symbol KG indicates the high temperature gas side, and the symbol KG indicates the low temperature gas side.
As shown by the arrow, cooling air is forced into the passage hole 2 under pressure from the low temperature gas side. A heat shielding element is fixed to the support structure 1, which has an umbrella part 3 and a handle part 5 like a mushroom. The handle part consists in this embodiment of an anchor bolt, which passes through a through hole 8 in the support structure 1. Thickened head of anchor bolt 5.
1 is held at a distance a1 from the hot gas side HG of the support structure 1 by a ring-shaped shoulder 5.2 and is attached to the support structure 1 by means of a fixing nut 5.3 screwed into the respective free end. The fixing nut is then tightened against the cold gas side KG of the supporting structure 1 in a manner that prevents it from loosening by means of welding points (not shown). The cooling air flowing through the cooling air passage holes 2 reaches the intermediate chamber 6 between the support structure 1 and the umbrella part 3, impinges on the lower surface 3.1 of the umbrella part 3 and along the lower surface 3.1. Cooling air flows into the gaps 4 between the individual umbrella parts 3. The rim 1.4 in the intermediate chamber 6 below the cooling air gap 4 forms a certain constriction point and prevents hot gases from penetrating into the intermediate chamber 6. The cooling air flowing out from the cooling air gap 4 is redirected by the high temperature gas flow flowing above it on the high temperature gas side HG, and the cooling air flows out from the cooling air gap 4.
forming a cooling air film on the top surface of the device, thereby producing an auxiliary cooling effect. Advantageously, both the umbrella part 3 of the individual heat shielding element and its handle part, the anchor bolt 5, are made of heat-resistant steel, for example, so that they can be welded together without any problems. The anchor bolts 5 are accordingly welded in each case to the central region 7 of the umbrella part. In this embodiment, in order to simply explain the principle of the invention, it is assumed that each heat shielding element has an equilateral triangular umbrella portion having the same shape. In general cases, the 6th
As shown in the figure, an irregularly curved surface must be assembled from various polygons, preferably triangles. Although such polygons or triangles always have a center of gravity that can be precisely defined, the anchor bolt does not necessarily have to be fixed exactly to this center of gravity. Although fixing at the center of gravity is generally advantageous, fixing off the center of gravity may be advantageous due to the tendency of the individual parts of the polygon to vibrate.

Providing only one fixation point for each heat shielding element has the advantage in all cases that the thermal expansion of the heat shielding element is unimpeded and therefore there is no risk of excessive thermal stresses occurring. On the cold gas side KG, for example, an average temperature of approximately 400 °C occurs during operation, and on the underside 3.1 of the umbrella part 3, an average temperature of, for example, 750 °C occurs predominantly, so that the support structure and the heat shielding element Although a difference in thermal expansion occurs between the two, the thermal expansion itself is not hindered. This is because the umbrella part 3, like the bolt head 5.1, can extend freely in all directions. Since the anchor bolt 5 is firmly screwed in with initial tension applied, there is no fear that it will loosen even if the temperature rises to the operating temperature. The umbrella part itself, which can reach an even higher temperature on the hot gas side HG than on its underside 3.1, is also not prevented from thermal expansion. The umbrella part may be on the high temperature gas side in some cases.
Although it may take a convex curved shape when viewed from HG,
This is accomplished without hindrance. The rim 1.4 provides a well-defined throttling point for the cooling air, which throttling point is adjusted in the manner described above to form a uniform cross section. It is therefore not important to precisely define the width of the cooling air gap 4 between the umbrella parts 3, as long as this width is sufficiently wide. This is also an advantage since this gap changes constantly in various operating conditions.

Another embodiment of the invention is shown in FIGS. 3, 4 and 5. The cooling principle remains the same, only the method of fixing the individual heat shielding elements has changed. Additionally, this example illustrates the placement of heat shielding elements on a non-planar support structure. FIG. 3 shows a longitudinal section of a part of the heat shielding device, FIG. 4 shows a cross section through the cutting plane shown in FIG. 3, and FIG. 5 shows a top view of the heat shielding element. Support structure 31
has here again cooling air passage holes 32 and a rigidly fixed heat shielding element with a triangular umbrella section 33. Between the individual umbrella parts 33 there is a cooling air gap 34 having a width a33. Between the support structure 31 and the underside 33.1 of the umbrella part 33 there is an intermediate chamber 36 of width a31. The umbrella part 33 has in its central region a pot-shaped profile 33.2, 33.3, which has a welding point 37 on its upper side 33.2.
On its lower side 33.3 it has a through hole 33.4. A bolt 35 is guided through this hole 33.4 and a corresponding through-hole 38 in the support structure 31, the bolt head 35.1 being replaced by a pot-shaped profile 33.2, 3.
3.3, preferably on the hot gas side HG
It is aligned in a straight line with the upper surface of the umbrella portion 33. The bolt head 35.1 can then have, for example, a hexagonal hole or similar engagement means for a screw-tightening tool.
This bolt is tightened by a nut towards the cold gas side KG of the support structure 31, the nut 35.2 having a claw-shaped arm 35.3 which rests on the support structure 31; And 35.4
Welded to the support structure at In this case, the nut 35.2 itself does not have to come into contact with the support structure 31, and the claw-shaped arm 35.3 provides a suitable initial tension. Furthermore, the through hole 38 and the corresponding hole 33.4 in the support structure 31 are clearly wider than the diameter of the bolt 35, at least in partial areas, so that the cooling air flows along the bolt 35, so that the bolt is particularly Its head 35.1 is cooled.
Appropriate outflow holes 33.6 are provided in the pot-shaped moldings 33.2, 33.3. Other solutions for maintaining the initial tension of the bolt 35 are also conceivable, such as extension bolts, disc springs, etc. For precise positioning of the heat shielding element, grooves 31.2, 33.3, in which the pot-shaped protrusions 33.2, 33.3 form-lock, are provided.
3 and is advantageously supported on a support structure 31. Additional cooling air passage holes, for example in the form of 33.6, can also be provided in the pot-shaped profiles 33.2, 33.3. Additional cooling air passage holes 33.7 can also be provided at points of the heat shielding element 33 that are particularly to be cooled, but these holes should not be aligned in a straight line with the cooling air holes 32.
FIG. 3 shows a more practical arrangement for the ridges 31.4, 31.6, 31.7 for forming the constriction points 39 for the cooling air flow. These edges can be provided initially during the formation of the support structure 31, for example by casting, or they can be installed later. As shown at the ridge 31.4, the ridge has a surface profile 31.5 adapted to the extent of the adjacent umbrella part 33, but this is not necessarily necessary insofar as a clear constriction point is formed. isn't it. It may be difficult to place the rim in the area of contact points of multiple heat shielding elements due to excessive material concentration. In this case, the platform edge is, for example, platform edge 3.
1.6, 31.7, it must have a special shape, for example a ring-shaped shape with a hemispherical cavity 31.8 inside.

As shown in FIG. 4, the upper surface 31.7 of the pedestal 31.7.
8, there is a recess 3 in a direction transverse to the extending direction of the pedestal edge.
1.9, this recess also ensures a minimum flow of cooling air when the heat shielding element contacts the pedestal edge. Such a recess is the umbrella portion 33.
It can also be provided on the bottom surface.

Finally, FIG. 6 shows an example for dividing a curved surface into appropriate triangles. For example, the inner casing of a gas turbine can be well approximated with a relatively small number of triangles without the need to curve the individual heat shielding elements. A better approximation of the shape is basically possible with a larger number of triangles, especially triangles, or by using curved heat shielding elements. However, an important advantage of using triangles is that the division of a curved surface into triangles causes the least problems later when producing heat shielding elements, since three points always define a plane. It is.

This invention is a high-temperature gas channel of a gas turbine,
Although it is particularly suitable for combustion chambers or similar parts, it is not limited to such applications. This heat shielding device can either make it possible to achieve higher temperatures inside the support structure or simplify its construction and reduce its load.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a heat shielding device according to the present invention, FIG. 2 is a cross-sectional view taken along the cutting line of the device shown in FIG. 1, FIG. 3 is a cross-sectional view of another embodiment of the device, and FIG. is a sectional view taken along the cutting line of the device shown in FIG. 3, FIG. 5 is a plan view of the heat shielding element shown in FIG. 3, and FIG. 6 shows a part of the surface of the support structure representing the heat shielding element. FIG. 3 is a perspective view showing an example of dividing into triangle groups. 1, 31...Support structure, 1.4, 31.4, 3
1.6, 31.7... Edge, 2, 32... Cooling air passage hole, 3, 33... Umbrella part, 4, 34... Cooling air gap, 5, 35... Handle part (bolt), 5.2... Ring Shoulder, 5.3, 35.2... Nut, 6, 36...
Intermediate chamber, 8, 38... Through hole, 31.3... Groove, 3
1.8...Top surface, 31.9...Bottom surface, 33.2,3
3.3... Molded part, 33.4... Hole, 33.5... Edge,
33.6...Outflow hole, 33.7...Cooling air outlet, 3
3.8...Vacancy, 35.1...Bolt head, 35.3
...Arm, 39...Aperture point, a1...Width, a31, a3
2... Spacing, HG... High temperature gas side, KG... Low temperature gas side.

Claims (1)

[Claims] 1 Comprising a cooling fluid passage hole 2; 32 in a support structure 1; In a heat shielding device for protecting a support structure against hot fluids, such as assembled from a plurality of parallelly arranged heat shield elements fixed to a possible support structure 1; 31, each heat shield Umbrella part 3; 33 and handle part 5; 35 whose elements are mushroom-shaped
and in which the umbrella part 3; 33 is a flat or three-dimensional polygonal plate with a straight or curved border, and the handle part 5; The central region and the support structure 1; 31 are connected, each facing a respective cooling fluid gap 4; 34 provided between the heat shielding elements, a pedestal edge 1.4;
31.4, 31.6, 31.7 extending in the direction of this gap and over approximately the entire length of this gap are arranged on the support structure 1; 31, with a predetermined restriction for the cooling fluid flow. Thermal shield characterized in that the dimensions of the distance a32 between the edge 1.4; 31.4, 31.6, 31.7 and the umbrella part 3; 33 are selected such that a point 39 occurs. Device. 2. Device according to claim 1, characterized in that the plane of the umbrella part 3; 33 forms a triangle, preferably a triangle in which all internal angles are larger than 40°, preferably larger than 50°. 3. Device according to claim 1, characterized in that the umbrella portion 3; 33 has approximately the shape of a section of the surface of the rotating body. 4 Anchor bolts, each of which has a handle part 5 connected to the umbrella part, pass through a through hole 8 of the support structure 1 and are supported by at least one fixing nut 5.3 screwed into its free end. A patent characterized in that each ring-shaped shoulder 5.2 or spacing ring or the like determines the width a1 of the intermediate chamber 6 between the umbrella part 3 and the support structure 1, which is fastened to the structure 1. An apparatus according to any one of claims 1 to 3. 5 a Each umbrella part 33 has a hole 3 in the lower surface 33.3.
3.4 and a pot-shaped profile 33.2, 33.3 facing the support structure 31 in the central region; It is guided in a form-locking groove 31.3 or the like and rests on the support structure 31, so that the distance a between the umbrella part 33 and the support structure 31 is
31 is determined, c bolts 35 inserted through holes 33.4 on the lower surface of pot-shaped molded parts 33.2, 33.3 and through holes 38 of support structure 31, and bolts 35 supported by support structure 31. A threaded connection, such as a nut 35.2, tightens the umbrella part 33 to the support structure 31;
In this case, the head 35.1 of the bolt is shaped like a pot 3.
3. Device according to any one of claims 1 to 3, characterized in that it is submerged within the canopy part 3.2, 33.3 and is preferably substantially aligned with the upper surface of the umbrella part. 6 The nut 35.2 is supported on the support structure 31 by means of a claw-shaped arm 35.3 or a collar, this arm 35.3 preferably being connected to the support structure 31.
6. Device according to claim 5, characterized in that it is firmly connected, in particular welded, to the device. 7. The umbrella part 3; 33, the anchor bolt 5; 35 and possibly other parts of the heat shielding element are
7. Device according to claim 1, characterized in that it is made of a heat-resistant material, in particular steel. 8 The support structure 1; 31 has holes 2; 32 through which the cooling fluid, in particular air, flows into the intermediate chamber 6; 36.
8, wherein the opening 2; 32 is preferably arranged perpendicularly to the umbrella part 3; 33. The device according to item 1. 9. The pedestal edge 31.7 is such that a minimum cooling fluid flow is ensured even if the umbrella portion 33 contacts the pedestal top surface.
2. Device according to claim 1, characterized in that the upper surface 31.8 and/or the lower surface 31.9 of the umbrella part 33 are configured. 10 Edge 1.5, 31.5, 31.6, 31.
In order that the shape of the upper surface of 7 is adapted to the extent of the adjacent umbrella part 3; 31.6,3
1. Device according to claim 1 or 9, characterized in that a special shape is used, such as 1.7 or a double ridge with a central groove on the top surface. 11 Edge 33.5 of umbrella portion 33 is high temperature gas side HG
11. Device according to any one of claims 1 to 10, characterized in that it is chamfered. 12 characterized in that in the area of the fastening part 5; 35 an auxiliary outflow hole 33.6 for the cooling fluid is provided, which provides for cooling of the fastening part 5; 35, in particular of its head 35.1; Claim 1
The device according to any one of items 1 to 11. 13. According to claim 12, the hole 8; 38 has an auxiliary cavity in its side wall, which cavity allows a cooling fluid to flow along the fastening part 35. equipment. 14 Umbrella portion 33 serves as auxiliary cooling fluid outlet 33.7
14. A device according to any one of claims 1 to 13, characterized in that it has: