The invention relates to a combustion chamber, in particular a combustion chamber of a gas turbine, having a support structure, a multiplicity of holding elements which are fastened to the support structure, and a multiplicity of heat shield elements which conjointly form a heat shield, have in each case a hot-gas side, a cold-gas side, and end sides that connect the hot-gas side and the cold-gas side to one another, wherein the holding elements engage in a form-fitting manner in recesses which are provided on the heat shield elements. The invention furthermore relates to an assembly and to a heat shield element for implementing such a combustion chamber.
The combustion chambers of gas turbines, for example, by virtue of the high temperatures prevalent during the operation are provided with a heat shield which protects the housing wall of the combustion chamber from the hot atmosphere in the combustion space of the combustion chamber. Heat shields which can resist hot gases with temperatures of, for example, approximately 1000° C. to approximately 1600° C. are known from DE 10 2017 206 502 A1, for example. Heat shields of this type are assembled from many individual planar heat shield elements. Depending on whether metallic or ceramic heat shield elements are used, reference is made to a metallic heat shield (MHS) or a ceramic heat shield (CHS). The heat shield elements, while leaving gaps between the end sides of adjacent heat shield elements, are positioned so as to lie next to one another. These gaps ensure that the heat shield elements during the operation of the combustion chamber can thermally expand in the circumferential direction of the heat shield. However, only a minor gap is left between the support structure and the heat shield elements. Holding elements, which are referred to as brick retainers, and made from metal are used for fixing a heat shield element to the support structure of the combustion chamber. Said holding elements comprise a C-shaped basic shape having two C-legs, specifically one long fastening leg configured for fastening to the support structure and a short engagement leg which is configured for engaging in a holding recess of the heat shield element at the end side, both legs being connected to one another by way of a web. The fastening leg bears on the support structure and is screwed to the latter at the end side.
The primary objective in refining modern stationary gas turbines lies in increasing the conversion efficiency, the latter being a function of the hot gas temperature, on the one hand, and the volumetric flow of cooling air required for cooling the metallic gas turbine components, on the other hand. The higher the hot gas temperature, the more efficient the operation of the gas turbine. However, the higher the volumetric flow of cooling air for protecting the metallic components, the lower the efficiency.
The previously mentioned holding elements require in particular sufficient cooling in order for the function of said holding elements to be able to be permanently guaranteed at the prevailing high temperatures. The volumetric flow of cooling air required for this cooling, which is directed between the support structure and the heat shield elements and as sealing air exits to the combustion chamber through the gaps which are present between the heat shield elements, has to be tapped from the primary volumetric flow of cooling air provided by the compressor and is correspondingly not available for the combustion process and thus not for generating the output of the gas turbine. The size of the gaps here has a strong influence on the volumetric flow of cooling air required. The smaller the gaps, the smaller the volumetric flow of cooling air required for achieving the sealing effect.
Proceeding from this prior art, it is an object of the present invention to further optimize a combustion chamber of the type mentioned at the outset in terms of the efficiency of said combustion chamber.
In order for this object to be achieved, the present invention achieves a combustion chamber of the type mentioned at the outset which is characterized in that the holding elements have in each case at least two engagement portions configured for engaging in a form-fitting manner in the recesses of a heat shield element, said engagement portions being connected to one another so as to provide tensile rigidity in such a manner that a diverging movement of the engagement portions is effectively counteracted at temperatures prevalent during the operation of the combustion chamber, and in that spring elements, configured in particular as leaf springs, which cause a force-fit between the engagement portions of the holding elements and the heat shield elements extend between the support structure and the heat shield elements, wherein the engagement portions per se are configured so as to provide tensile rigidity in such a manner that said engagement portions under the effect of the spring forces are dimensionally stable at the temperatures prevalent during the operation of the combustion chamber. A substantial advantage which is associated with a combustion chamber constructed according to the invention, lies in that the gap size between adjacent heat shield elements can in particular be significantly reduced. This is because sufficient space between the support structure and the heat shield elements can be left in such a manner that the heat shield elements during the operation of the combustion chamber can freely expand in the radial direction, as a result of which the expansion of said heat shield elements in the circumferential direction is reduced, on the one hand. On the other hand, additional movements of the heat shield elements caused by a deformation of the holding elements is effectively counteracted thanks to the holding elements according to the invention being configured so as to provide tensile rigidity. As a result, the maximum temperature at which the combustion chamber can be operated can be increased to, for example, 1600° C., which consequently results in an improved output. At the same time, thanks to the narrower gaps between the heat shield elements, the volumetric flow of cooling air can be reduced by up to an estimated 50%, this likewise contributing to an improved output. Moreover, the maintenance intervals can also be increased thanks to the improved thermal shielding of the holding elements.
The recesses are advantageously configured on the cold sides of the heat shield elements. In comparison to recesses disposed on the end side, this has the advantage that the engagement portions of the holding elements which engage in the recesses are better thermally shielded and can also be better cooled by the cooling air.
According to one design embodiment of the present invention, the support structure is provided with circumferentially extending receptacle grooves for receiving the holding elements, as a result of which the assembling and fastening of the holding elements are improved.
Holding elements which are disposed so as to be circumferentially adjacent to one another are advantageously releasably connected to one another by way of connecting elements. Connecting elements of this type serve for equalizing tolerances in the circumferential direction. The connecting elements are in particular screwed to the support structure so as to position the holding elements and thus the heat shield elements in the circumferential direction of the combustion chamber.
The receptacle grooves advantageously have a cross section provided with undercuts, wherein the holding elements and/or the connecting elements are received in a form-fitting manner in the receptacle grooves. In this way, the holding elements and thus the heat shield elements are secured in the radial direction as well as the axial direction of the combustion chamber.
According to one design embodiment of the present invention, the holding elements have a fastening portion which points toward the support structure and is configured so as to provide tensile rigidity, and at least two engagement portions which project from the fastening portion and are in particular configured so as to be integral to the latter, wherein each heat shield element has a number of cold-gas proximal recesses, the number of the latter corresponding at least to the number of engagement portions of a holding element, and wherein each engagement portion engages in a form-fitting manner in one of the recesses. A very simple construction is implemented in this way.
The cold-gas proximal recesses of the heat shield element are advantageously configured so as to be elongate, defining in each case one insertion region and, adjoining the latter in the longitudinal direction, one engagement region, wherein the insertion region is configured in such a manner that an assigned engagement portion of a holding element can be inserted radially into said insertion region, the engagement region being conceived for receiving the engagement portion in a form-fitting manner, and the insertion region and the engagement region being configured in such a manner that an engagement portion which is inserted radially into the insertion region can be transferred into the engagement region by being displaced in the longitudinal direction. A construction of this type results in simple assembling.
The fastening portion is advantageously configured in the form of an elongate plate which is in particular curved in the manner of a circular ring segment, wherein the engagement portions are provided in the region of the free ends of the fastening portion.
The engagement portions advantageously project from the fastening portion at an angle which differs from 90°. Alternatively or additionally, the engagement portions can be provided with end regions pointing toward or away from one another.
The fastening portion on the upper side thereof that points toward the heat shield element is advantageously provided with a depression which is conceived for receiving at least one of the spring elements. Accordingly, the at least one spring element can be easily positioned during assembling and subsequently also maintains its position.
According to one design embodiment of the present invention, at least one spring element is in each case guided in such a manner through a passage opening configured on the fastening portion that said at least one spring element in a central region is supported in relation to the support structure. As a result thereof, the advantage of less flexural stress on the fastening portion is obtained. As a consequence of the flexurally stiff mating face of the support structure, the loss in terms of the preloading of the spring elements as a consequence of the creeping deformation of the supporting fastening portion is reduced.
The fastening portions of the holding elements and the spring elements are advantageously provided with correspondingly disposed elongate bores through which tension bolts for pulling the spring elements in the direction of the fastening portions can be inserted. Tension bolts of this type are used for overcoming the spring force of the at least one spring element while the holding element and the at least one spring element are assembled on a heat shield element. The tension bolts are removed again after assembling, so as to generate the desired force-fit between the engagement portions of the holding element and the heat shield element.
According to one design embodiment of the present invention, each heat shield element is held to the support structure by way of two holding elements, in particular by way of exactly two holding elements.
The shaping of the holding elements advantageously takes place while using a casting process or an additive manufacturing method, optionally with subsequent machining. The holding elements according to the invention, as opposed to the holding elements which are described in DE 10 2017 206 502, are thus not bent from a stamped metal sheet. Holding elements of this type, which are bent from a metal sheet also do not have the tensile rigidity in the circumferential direction and in the radial direction, as required according to the invention.
For achieving the object mentioned at the outset, the present invention furthermore achieves an assembly comprising at least one holding element and at least one spring element, wherein the assembly is conceived for implementing a combustion chamber according to the invention. In other words, the at least one holding element as well as the at least one spring element can have those features which have already been described above in the context of the respective component.
The present invention furthermore achieves a heat shield element which is conceived for implementing a combustion chamber according to the invention.
Further advantages and features of the present invention will become evident by means of the description hereunder of combustion chambers according to embodiments of the present invention with reference to the appended drawing, in which:
The same reference signs hereunder refer to identical components or regions of components, respectively, or to components or regions of components of identical configuration, respectively.
The support structure 2 is made of metal and is provided with a multiplicity of receptacle grooves 11 which extend circumferentially and are disposed so as to be mutually parallel and have a cross section provided with undercuts, presently a cross section having groove walls which are configured in the shape of steps, said cross section decreasing from the base of the groove to the opening of the groove. The receptacle grooves 11 serve for receiving the holding elements 3 as well as the connecting elements 4, as is described in detail hereunder. However, only the connecting elements 4 have a cross section which corresponds to the cross section of the receptacle grooves 11 such that said connecting elements 4, upon being inserted into one of the receptacle grooves 11, are correspondingly secured by a form-fit in the radial direction R as well as in the axial direction A. The holding elements 3, upon being inserted into a receptacle groove 11, are however secured by a form-fit only in the axial direction A.
The holding elements 3 are made integrally of metal and have substantially a U-shape which is formed by a fastening portion 12 in the form of an elongate plate which is bent in the manner of a circular ring segment, and by two engagement portions 13 which project from the end regions of the fastening portion 12. The fastening portion 12 serves for fastening the holding element 3 in one of the receptacle grooves 11 of the support structure 2. The width of the fastening portion 12 is to this end adapted to the width of the receptacle grooves 11. The lateral walls of the fastening portion 12 are configured so as to be straight, without protrusions, such that the fastening portion 12 can be inserted radially into one of the receptacle grooves 11. The engagement elements 13 by way of the fastening portion 12 are connected to one another so as to provide tensile rigidity in such a manner that a diverging movement of the engagement portions 13 is effectively counteracted at the temperatures prevalent during the operation of the combustion chamber. Furthermore, the engagement portions 13 per se are configured so as to provide tensile rigidity in such a manner that said engagement portions 13 under the action of the spring forces of the spring elements 10 are dimensionally stable at the temperatures prevalent during the operation of the combustion chamber. These tensile strengths are primarily achieved by suitably dimensioning the webs that define the fastening portion 12 and the engagement portions 13. The engagement portions 13 project from the fastening portion 12 at an angle which differs from 90°, presently being approximately 60°, such that the engagement portions 13 are inclined toward one another. In order to receive presently in each case two spring elements 10, each holding element 3 in the central portion of the fastening portion 12 thereof comprises an elongate passage opening 14 which, proceeding from the upper side of the fastening portion 12 from which the engagement portions 13 project, extends to the opposite lower side. The passage opening in the transverse direction is subdivided in an approximately centrical manner by a separation web 15 which however extends only in the upper region of the passage opening 14. This separation web serves for preventing the spring elements 10, which are inserted into the passage opening 14 as shown in
The heat shield elements 8 presently are configured as CHS heat shield elements and have a completely closed hot-gas side 5. The recesses 9 into which the engagement portions 13 of the holding elements 3 engage are provided on the cold-gas side 6 of the heat shield elements 8. Each heat shield element 8 presently comprises two elongate recesses 9 which extend so as to be mutually parallel and are disposed at a mutual spacing, the latter corresponding to the spacing between the engagement portions 13 of a holding element 3. Each recess 9 defines an insertion region 19 and, adjoining the latter in the longitudinal direction, an engagement region 20. The insertion region 19 is configured in such a manner that an assigned engagement portion 13 of a holding element 3 can be inserted radially into said insertion region 19. The engagement region 12 is however conceived for receiving in a form-fitting manner the corresponding engagement portion 13, wherein the insertion region 19 and the engagement region 20 are configured in such a manner that an engagement portion 13 inserted radially into the insertion region 19 can be transferred into the engagement region 20 by being displaced in the longitudinal direction, see to this end in particular
Two holding elements 3 and four spring elements 10 are required in order for one heat shield element 8 to be assembled. In a first step, two spring elements 10 are in each case inserted into the passage opening 14 of a holding element 4. In a second step, tension bolts 23 are inserted through the elongate bores 16 of the fastening portion 12 and the elongate bores 17 of the spring elements 10, and the free ends of the spring elements 10, while using the tension bolts 23, are pulled in the direction of the fastening portion 12, as is shown in
The assembly described above is distinguished in particular in that the gap width B between heat shield elements 8 disposed adjacent to one another can be chosen to be very minor. The reason therefor lies primarily in the holding elements 3 which are configured so as to provide tensile rigidity, on the one hand, and in the fact that the heating shield elements 8 are positioned at a comparatively large spacing from the support structure 2, which is why the heat shield elements 8 can readily expand in the radial direction R during the operation of the combustion chamber, on the other hand. Thanks to the minor gap width B, only a minor volumetric flow of sealing air is required, this being associated with a significantly increased efficiency of the gas turbine. Moreover, by virtue of the fact that the recesses 9 are provided on the cold-gas side 6 of the heat shield elements 8, the holding elements 3 are completely covered by the heat shield elements 8 and correspondingly better thermally protected, such that the cooling requirement of the holding elements 3 is also less. The same applies to the required maintenance because the holding elements 3 are subjected to less wear.
While the invention has been illustrated and described in detail by way of the exemplary embodiment, the invention is not limited by the disclosed examples and other variations here can be derived by the person skilled in the art without departing from the scope of protection of the invention.
Number | Date | Country | Kind |
---|---|---|---|
10 2019 200 593.4 | Jan 2019 | DE | national |
This application is the US National Stage of International Application No. PCT/EP2019/085232 filed 16 Dec. 2019, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 10 2019 200 593.4 filed 17 Jan. 2019. All of the applications are incorporated by reference herein in their entirety.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2019/085232 | 12/16/2019 | WO | 00 |