Title of Invention | HEAT-SHIELD ARRANGEMENT FOR A COMPONENT DIRECTING HOT GAS |
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Abstract | The invention relates to a heat-shield component (1) having an outer hollow body (100) and an insert (110) which in each case can be attached to a supporting structure (17). The outer hollow body (100) encloses the insert (110) while leaving an intermediate space (151). The outer hollow body (100) has a first base side (101) which can be exposed to a hot gas. The insert (110) has a second base side (111) having a plurality of openings (113) for the passage of cooling fluid (4) into the intermediate space (151) for impingement cooling of the first base side (101). The invention also relates to a heat shield arrangement (20). |
Full Text | The invention relates to a heat-shield component which is part of a hot-gas wall to be cooled. Further- more, the invention relates to a heat-shield arrangement which lines a hot-gas space, in particular a combustion chamber of a gas-turbine plant, and has a plurality of heat-shield components. On account of the high temperatures which prevail in hot-gas passages or other hot-gas spaces, it is necessary for the inner wall of a hot-gas passage to be designed in the best possible way in terms of temper- ature-resistance. On the one hand, high-temperature- resistant materials, such as, for example, ceramics, are suitable for this purpose. The disadvantage of ceramic materials lies both in their great brittleness and in their unfavourable heat and temperature conductivity. A suitable alternative to ceramic materials for heat shields are high-temperature-resistant metal alloys on an iron, chromium, nickel or cobalt basis. However, since the service temperature of high-temperature-resistant metal alloys is markedly below the maximum service temperature of ceramic materials, it is necessary to cool metallic heat shields in hot-gas passages. One possibility is proposed, for example, by Craemer in US 4,838,031 of 13 th June 1989. Craemer proposes a panel which consists of four components and is to be mounted on the inside of a combustion-chamber casing. In this case, the top layer facing the hot-gas space is made of a refractory metal, but may also be formed by a ceramic material. This is followed underneath by a layer of steel-wool-like metallic filaments. These filaments rest on a relatively large number of column- like supports. These column-like supports and the cavities in between form the third layer. The column-like supports are attached to a fourth metallic layer. The steel-wool-like metallic filaments of the second layer absorb heat energy from the overlying layer forming the inner burner wall and transfer said heat energy to the air flow directed between the column-like supports. In this case, the cavities of the third layer, via passages which lead through the fourth layer and the burner casing, are connected to a space outside the burner, and this space is fed with air via a compressor. The compressed air, as coolant, can pass through these passages into the cavity formed by the layers. In addition, a second type of passage is distri- buted over the front and centre region of the combustion chamber, through which passages the air originating from the exterior of the combustion chamber passes through the combustion-chamber casing and the layered panels into the combustion chamber. The proposal by Craemer has the disadvantage that cool eiir flows into the combustion chamber over the entire region of the latter without having participated in the combustion. As a consequence thereof, the temper- ature at the outlet of the combustion chamber drops. A heat-shield arrangement, in particular for. structtiral parts of gas-turbine plants, is described in EP 0 224 817 B1. The heat-shield arrangement has an inner lining which is made of heat-resistant material and is composed of heat-shield elements in such a way as to cover the surface, which heat-shield elements are anchored to the supporting structure. These heat-shield elements are arranged next to one another while leaving gaps for the throughflow of cooling fluid and are thermally movable. Each of these heat-shield elements has a cap part and a shank part like a mushroom. The cap part is a flat or spatial, polygonal plate body having straight or curved boundary lines. The shank part con- nects the central region of the plate body to the sup- porting structure. The cap part preferably has a tri- angular shape, as a result of which an inner lining of virtually any geometry can be produced by identical cap parts. The cap parts as well as if need be other parts of the heat-shield elements are made of a high-temperature- resistant material, in particular a steel. The supporting structure has bores through which a cooling fluid, in particular air, can flow into an intermediate space between cap part and supporting structure and can flow from there through the gaps, intended for the throughflow of the cooling fluid, into a spatial region, for example a combustion chamber of a gas-turbine plant, surrounded by the heat-shield elements. This cooling fluid flow reduces the ingress of hot gas into the intermediate space. Described in DE 35 42 532 A1 is a wall, in particular for gas-turbine plants, which has cooling- fluid passages. In gas-turbine plants, the wall is preferably arranged between a hot space and a cooling- fluid space. It is assembled from individual wall elements, each of the wall elements being a plate body made of a high-temperature-resistant material. Each plate body has parallel cooling passages which are distributed over its surface area and communicate at one end with the cooling-fluid space and at the other end with the hot space. The cooling fluid, flowing into the hot space and directed through the cooling-fluid passages, forms a cooling-fluid film on that surface of the wall element and/or adjacent wall elements which faces the hot space. In summary, all of these heat-shield arrange- ments, in particular for gas-turbine combustion chambers, are based on the principle that compressor air is utilized as cooling medium for the combustion chamber and its lining and also as sealing air. The cooling and sealing air enters the combustion chamber without having participated in the combustion. This cold air mixes with the hot gas. As a result, the temperature at the outlet of the combustion chamber drops. Therefore the output of the gas turbine and the efficiency of the thermodynamic process decrease. Partial compensation may be carried out by a higher flame temperature being set. However, this then results in material problems, and higher emission values have to be tolerated. It is likewise a dis- advantage with the arrangements specified that, in the case of the air fed to the burner, pressure losses result due to the entry of the cooling fluid into the combustion chamber. Described in the subsequently published WO I 9 8/13 645 A1 is a heat-shield component with cooling-fluid return, having a hot-gas wall to be cooled, an inlet passage for cooling fluid, and an outlet passage for the cooling fluid, the inlet passage being directed towards the hot-gas wall and widening in the direction of the hot-gas wall. The inlet passage is largely surrounded by the outlet passage. The supporting structure is designed as a twin-wall structure, having an outer wall and an inner wall arranged parallel to and adjacent to the outer wall while leaving an intermediate space. For fastening to the supporting structure, the heat-shield component, at the outlet passage, has a fastening part with which the outlet passage is put onto the outer wall and fastened to the latter. Inside the outlet passage, the outer wall has an opening through which the inlet passage is directed while leaving a gap. The inner wall has a further opening into which the inlet passage is pushed over a short length. Cooling fluid can be fed to the heat-shield component via the inlet passage and dis- charged via the outlet passage. The inlet passage is covered with a cover wall which has impingement-cooling openings. Through the impingement-cooling opening, cooling fluid fed from the inlet passage can strike the hot-gas wall, in the course of which the latter is cooled. The object of the invention, for a hot-gas space of a plant, is to specify a heat-shield component which can be cooled with a cooling fluid as well as a heat- shield arrangement having heat-shield components, which heat-shield arrangement permits economical operation of the plant. The object which relates to the heat-shield component is achieved according to the invention by a heat-shield component which can be attached to a support- ing structure and has an outer hollow body which encloses an insert with an intermediate space formed between the outer hollow body and the insert, the outer hollow body having a first base side which can be exposed to a hot gas and side walls, and the insert having side walls and a second base side having a plurality of openings for the passage of cooling fluid into the intermediate space, the outer hollow body and the insert in each case being attachable to the supporting structure. The heat-shield component can be attached to the supporting structure without the supporting structure having to be penetrated by the heat-shield component. As a result, the supporting structure can be configured largely with a closed sur- face, in which case relatively small openings, such as bores or the like, may be provided if need be, for example for fastening the heat-shield component in the supporting structure, which bores can be made in a mechanically simple manner. The side walls of the insert can preferably be put onto the supporting structure in such a way that an interior space, which is defined by the insert and the supporting structure, is formed. An interior space fluidically connected to the intermediate space via the openings is thereby formed, into which interior space a cooling fluid can be directed to begin with, and this cooling fluid flows through the openings into the inter- mediate space and strikes the first base side in order to cool the latter. In particular, the top edges of the side walls of the hollow body are disposed on the supporting structure along the full periphery of the heat-shield component and largely seal off the space, in which the cooling fluid is located, relative to the hot-gas space. The side walls of the hollow body preferably have a geometrical form which enables a seal to be introduced between hollow body and supporting structure. The seal may be designed, for example, as a compression seal. In this case, due to the geometry of the hollow body, the seal lies on the cold side of the heat-shield component. The insert is also preferably exchangeable. The heat-shield component is thereby configured in such a way that, if need be, the insert or the outer hollow body can in each case be exchanged on its own. A first outer hollow body and a second outer hollow body are preferably attachable next to one another on the supporting structure, a side wall of the first outer hollow body and a side wall of the second outer hollow body being adjacent to one another while leaving a gap, the side walls in each case having a surface contour such that the gap is winding. As a result, the gap forms a choke point via which hot gas directed outside the heat-shield component can penetrate into the gap only with difficulty or cooling fluid issuing from the heat-shield component can pass through the gap only with difficulty. This can be achieved, for example, by interlocking steps or indentations of adjacent side walls of hollow bodies. As a result, cooling fluid or hot gas passing into the gap is deflected several times. The inner base side of the hollow body can preferably have cooling ribs or the like, as a result of which the cooling with a cooling fluid can be optimized. The heat-shield components are preferably fastened to the supporting structure via a centrally attached retaining bolt. The retaining bolt may be provided with disc springs so that greater resilience is ensured if the heat-shield component exceeds the permissible expansion. For reasons of simple assembly, the retaining bolt can be attached to the hot side of the heat-shield component. However, it is also possible for the restaining bolt to be located on the cold side of the heat-shield component. The latter has an advantageous effect on the corrosion properties of the heat-shield component. The base side of the hollow body may alternative- ly have a triangular, four-cornered (in particular quadrilateral or trapezoidal) or hexagonal surface area. Other suitable geometrical forms are also possible. For quadratic base sides of the hollow body, the typical order of magnitude is around 200 mm edge length. The wall thickness of the base side of the hollow body is prefer- ably less than 10 mm, in particular preferably between 3 and 5 mm. A relatively small temperature difference between inner and outer surfaces of the base side of the hollow body is thereby ensured. A high alternating-load resistance of the heat-shield component can thus be achieved. The heat-shield component is made of a heat- resistant material, in particular a metal or a metal alloy. It is advantageous to produce the heat-shield component, in particular the hollow body, as an invest- ment casting. The object which relates to the heat-shield arrangement is achieved according to the invention by a heat-shield arrangement which comprises a plurality of heat-shield components which are arranged next to one another on a supporting structure, a heat-shield component being attachable to the supporting structure and having an outer hollow body which encloses an insert with an intermediate space formed between the outer hollow body and the insert, the outer hollow body having a first base side which can be exposed to a hot gas and side walls, and the insert having side walls and a second base side having a plurality of openings for the passage of cooling fluid into the intermediate space, the outer hollow body and the insert in each case being attachable to the supporting structure, and a wall of a component directing hot gas, in particular of a combustion chamber of a gas-turbine plant, which wall can be exposed to a hot gas, being formed by the base sides of the heat- shield component. A component directing hot gas, in particular a combustion chamber of a gas turbine, can be lined with such a heat-shield arrangement, the heat-shield arrange- ment protecting the supporting structure, which may, for example, be a wall of the combustion chamber, against the heat effect caused by the hot gas. The individual heat- shield components can be cooled with a closed cooling- fluid circuit. The supporting structure for the heat-shield component preferably has in each case an inlet passage for cooling fluid in a first region inside the side walls of the insert and an outlet passage into the intermediate space for cooling fluid. In this way, cooling fluid can be directed via the inlet passage into the insert of a heat-shield component, from which the cooling fluid passes through the openings into the intermediate space for impingement cooling of the respective first base side. The cooling fluid can be discharged from the intermediate space via the outlet passage. It is also preferable for the inlet passage to be connected to a feed passage, which is arranged outside the hot-gas space, and for the outlet passage to be connected to a discharge passage, which is likewise arranged outside the hot-gas space. Thus, cooling fluid can be fed to the inlet passage via the feed passage, and the cooling fluid heated after the impingement cooling can be discharged via the outlet passage and a discharge passage. In this way, cooling fluid can be directed in a closed cooling-fluid circuit. The cooling fluid can preferably be fed to the heat-shiesld component from a compressor, in particular of a gas turbine, via the feed passage and is discharged via the discharge passage, and in the process is fed in particular to a burner. The cooling fluid can therefore be bled from a compressor in a simple manner and, heated after a cooling action, can be fed to a burner for the combustion. All the compressor air can therefore be supplied to the combustion. This ensures that the cooling fluid merely flows through the heat-shield component and is not able to penetrate into the hot-gas space. Due to this complete return of the cooling air from the heat-shield components, mixing of hot gas and cooling fluid accord- ingly does not occur, so that, if need be, a lower hot- gas temperature can be set in a gas-turbine plant. This is associated with a reduction in the nitrogen-oxide pollution. Due to the closed cooling-air return, there is likewise no flow around the edges of a heat-shield component, so that a largely uniform temperature dis- tribution with low thermal stresses occurs in the material of the heat-shield component. The supply of cooling air to the heat-shield component and the return of the heated cooling air to a burner of the gas-turbine plant are preferably effected via axially parallel supply passages. The passages can be widened as desired in the radial direction and their cross-sections can be adapted to the requisite cooling- air quantities. All the heat-shield components therefore have essentially identical cooling-air inlet conditions. The flow path to the heat-shield components or of heated cooling air to the burner is only affected by relatively slight pressure losses on account of its shortness. Furthermore, pressure losses no longer occur owing to the fact that no cooling fluid penetrates into the hot-gas space. The supply to the heat-shield components arranged on an outer side of a rotationally symmetrical component directing hot gas, in particular a combustion chamber of a gas-turbine plant, is preferably effected via the guide blades of the first guide-blade row of the gas turbine. If the quantity of cooling air which can be directed through the guide blades is insuf- ficient for adequate cooling of the heat-shield components, it is possible to direct supply passages past the outer side of the component directing hot gas, in particular the combustion chamber. The return of the heated cooling air is prefer- ably effected via separate discharge passages which lead directly to a burner of a gas-turbine plant. It is likewise possible to lead the outlet passage of the heat- shield components directly into a main passage in which the compressor air is fed to the burner. In this way, the heat absorbed in the heat-shield components can be fed again to the gas-turbine process in an especially favour- able manner. An exemplary embodiment of a heat-shield component and a heat-shield arrangement in a gas-turbine plant is given below. In the drawings: Fig. 1 shows a gas-turbine plant partly cut open in longitudinal direction and having an annular combustion chamber, Fig. 2 shows a longitudinal section through a heat- shield component having a supporting structure, a feed passage and a discharge passage, and Fig. 3 shows a sectional representation of the side walls of adjacent hollow bodies, which are put onto a supporting structure. Fig. 1 shows a gas-turbine plant 10 which is shown partly cut open longitudinally. The gas-turbine plant. 10 has a shaft 2 6 and, connected one behind the other in the axial direction, a compressor 9, an annular combustion chamber 11 and the blading (guide blades 18, moving blades 27) . Combustion air is compressed and heated in the compressor 9, and this combustion air is partly fed as cooling fluid 4(shown in fig-2) to a heat-shield arrange- ment 20. The compressed air is fed to a plurality of burners 25 which are arranged in a circle around the annular combustion chamber 11. A fuel (not shown) burned with the compressor air in the burners 25 forms a hot gas 29 in the combustion chamber 11, and this hot gas 29 flows out of the combustion chamber 11 into the blading of the gas-turbine plant 10 (guide blade 18, moving blade 27) and thus causes the shaft 2 6 to rotate. In this case, provision is made for the entire combustion-chamber wall to be lined with the heat-shield components according to the invention, which have the form of hollow tiles, or for it to be composed of such tiles,which are held on a supporting structure outside the combustion space. A heat-shield component is schematically shown in Fig. 2. The heat-shield component as a whole has the reference numeral 1. It has a hollow body 100, the base side 101 of which can be exposed to a hot gas. This ("first") base side 101 is exposed to a hot-gas stream 29. The hollow body 100 is laterally defined by the side walls 102. These side walls 102 are disposed with their bottom margin on the supporting structure 17. A further smaller hollow body is located as insert 110 in the hollow body 100. This insert 110 has passage openings 113 at its base side 111. The insert 110 is laterally defined by its side walls 112. The side walls 112 are disposed with their margin on the supporting structure 17. An interior space 150, which is defined by the insert 110 and the supporting structure 17, is thereby formed. Also formed in this way is an intermediate space 151, which is defined by the insert 110, the hollow body 100 and the supporting structure 17. In the region 162 which is located between the side walls 112 of the insert 110, the supporting structure 17 has one or more inlet passages 3, through which a cooling fluid 4 can pass into the interior space 150. Furthermore, the supporting structure 17 has outlet passages 5 into the intermediate space 151. For impingement cooling of the base side 101, cooling fluid 4 flows through the inlet passages 3 into the interior space 150 of the insert 110 and passes through the passage openings 113 into the intermediate space 151, in the course of which it strikes the inside 103 of the base side 101. The cooling fluid heated after the impingement cooling is discharged from the intermediate space via the outlet passages 5, as indicated by the arrows in Fig. 2. The cooling fluid 4 is therefore directed in a closed circuit. This avoids a situation in which the cooling fluid 4 passes into the hot-gas space 37. By the attachment of seals 34, it is possible to prevent leakage flows between the supporting structure 17 and the side wall 102, sitting thereon, of the hollow body 100. Here, the seals 34 are designed as compression seals, the side wall 102 of the hollow body 100 having a shoulder, by means of which the seal 34 is pressed onto the supporting structure 17 in the region of the connect- ing point between the side wall 102 of the hollow body 100 and the supporting structure 17. The cooling fluid 4 is supplied in such a way that the cooling fluid 4 is fed to the inlet passages 3 from a compressor 9 through a feed passage 12. In this case, this feed passage 12 lies outside the hot-gas space 37. The cooling fluid 4 is discharged via a discharge passage 13 likewise lying outside the hot-gas space 37. The cooling fluid 4 can be fed, for example, to the burner 2 5 through this discharge passage 13. In the exemplary embodiment shown, the heat- shield component 1 is fixed to the supporting structure 17 by a retaining bolt 130. This retaining bolt 130 is arranged in the centre of the rectangular embodiment shown. Its axis is oriented along the main axis 32 of the heat-shield component. In the exemplary embodiment, the retaining bolt is made with a thickened portion on the hot side of the heat-shield component 1 and is mounted with its thinner end on the supporting structure 17. The retaining bolt may be provided with disc springs (not shown here) in order to compensate for a situation in which the permissible thermal expansion of the heat- shield component 1 is exceeded. If the insert 110 and the hollow body 100 are connected in a mechanically detachable manner only via the retaining bolt 13 0, the inserts can be exchanged for other inserts which produce another cooling-fluid flow zone in the intermediate space 35 between the hollow body 100 and the insert 110. The cooling conditions for the base side 101 of the hollow body 100 can thereby be adapted to the specific requirements which result from the position of the heat-shield component 1 in the hot- gas passage. Fig. 3 shows a cutaway portion of a heat-shield arrangement. The heat-shield arrangement is formed from a plurality of heat-shield components arranged on the supporting structure 17, only two heat-shield components 100 and 100A being shown for the sake of clarity, in which case two side walls 102 and 102A of two adjacent hollow bodies 100 and 100A as well as a part of the supporting structure 17 can be seen. Here, cooling ribs on the first base side, which run radially relative to the side walls 102, are indicated by 115 and 115A. The base sides 101 and 101A of the heat-shield components 100 and 100A, with the base sides of the heat-shield components which are not shown in any more detail, form a wall 160 which can be exposed to a hot gas. The adjacent side walls 102 of the hollow bodies 100 have a mutually corresponding surface contour. This surface contour is configured in such a way that the side wall 102A of the hollow body 100A shown on the right-hand side in the drawing has a shoulder 105, with which a mating shoulder 104 of the side wall 102 of the hollow body 100 shown on the left-hand side corresponds. Due to this shaping with shoulder 105 and mating shoulder 104, no linear gap 3 6 leads to the supporting structure 17 from the hot-gas space 37. This ensures even better protection of the supporting structure 17 from heating by the hot gas in the hot-gas space 37. Since the hollow bodies 100 can be manufactured by the investment-casting process, geometrical forms such as those described cause no manufacturing difficulties. It is of course also possible, for the side walls 102 and 102A of the hollow bodies 100 and 100A, to select other geometrical forms in which a linear gap between hot-gas space 37 and support- ing structure 17 is avoided. We Claim: 1. Heat-shield arrangement (20) comprising a plurality of heat-shield components (1) arranged next to one another on a supporting structure (17), each said heat-shield component (1) being attachable to said supporting structure (17) and having an outer hollow body (100) enclosing an insert (110) with an intermediate space (151) formed between said outer hollow body (100) and said insert (110), said outer hollow body (100) comprising a first base side (101) being exposed to a hot gas, and-a-side walls (102), said insert (110) comprising a side walls (112) and a second base side (111) with a plurality of openings (113) for the passage of cooling fluid (4) into said intermediate space (151), the outer hollow body (100) and the insert (110) in each case being attachable to the supporting structure (17), and a wall (160) of a component directing hot gas, in particular of a combustion chamber of a gas-turbine plant, which wall (160) can be exposed to a hot gas, being formed by the base sides (101 ,111) of the heat-shield component (1). 2. Heat-shield arrangement (20) as claimed in claim 1, wherein said supporting structure (17) of each said heat shield component (1) has in each case an inlet passage (3) for cooling fluid (4) in a first inside region (162) of the side walls (112) of the insert (110), and an outlet passage (5) into the intermediate space (151) for cooling fluid (4). Heat-shield arrangement (20) as claimed in claim 2, wherein said inlet passage (3) is connected to a feed passage (12), which is arranged outside the hot-gas space (37), and the outlet passage (5) is connected to a discharge passage (13), which is like wise arranged outside the hot-gas space (37). Heat-shield arrangement (20) as claimed in claim 3 wherein a compressor (9) is provided for supply of said cooling fluid (4) being directed in particular to a burner (25) from said heat-shield component (1) via the feed passage (12) and the discharge passage (13). Heat-shield arrangement (20) as claimed in claim 1, wherein said side walls (112) of the insert (110) can be put on to the supporting structure (17) in such a way that an interior space (150), which is defined by the insert (110) and the supporting structure (17), is formed. Heat-shield arrangement as claimed in claim 5, wherein said insert (110) being exchangeable. Heat-shield arrangement (20) as claimed in claim 1, wherein said outer hollow body (100) comprises a first outer hollow body (100) and a second outer hollow body (100A) being attachable next to one another on the supporting structure (17), so that said side wall (102) of the first outer hollow body (100) and a side wall (102A) of the second outer hollow body (100A) are adjacent to one another while leaving a gap (36), said side walls (102,102A) in each case having a surface contour such that the gap (36) is winding. Heat-shield arrangement (20) as claimed in claim 1, wherein said first base side (101) having a plurality of cooling ribs (115) or structural elements on its surface (103) facing the intermediate space (151). Heat-shield arrangement (20) as claimed in claim 1, wherein said heat -shield component (1) having a centrally arranged retaining bolt (130) for fastening to the supporting structure (17). . Heat-shield arrangement (20) as claimed in any of the preceding claims, wherein the side walls (102) of the hollow body (100) are configured to attach a seal (34) relative to the supporting structure (17) Heat-shield arrangement (20) as claimed in one of the preceding claims, wherein the base side (101) of the hollow body (100) is triangular, hexagonal or four-cornered, in particular quadrilateral or trapezoidal. The invention relates to a heat-shield component (1) having an outer hollow body (100) and an insert (110) which in each case can be attached to a supporting structure (17). The outer hollow body (100) encloses the insert (110) while leaving an intermediate space (151). The outer hollow body (100) has a first base side (101) which can be exposed to a hot gas. The insert (110) has a second base side (111) having a plurality of openings (113) for the passage of cooling fluid (4) into the intermediate space (151) for impingement cooling of the first base side (101). The invention also relates to a heat-shield arrangement (20) |
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01454-cal-1998-correspondence.pdf
01454-cal-1998-description (complete).pdf
01454-cal-1998-letter patent.pdf
1454-CAL-1998-(12-10-2012)-FORM-27.pdf
1454-CAL-1998-OTHER PATENT DOCUMENT.pdf
Patent Number | 211014 | ||||||||
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Indian Patent Application Number | 1454/CAL/1998 | ||||||||
PG Journal Number | 42/2007 | ||||||||
Publication Date | 19-Oct-2007 | ||||||||
Grant Date | 16-Oct-2007 | ||||||||
Date of Filing | 14-Aug-1998 | ||||||||
Name of Patentee | SIEMENS AKTIENGESELLSCHAFT | ||||||||
Applicant Address | WITTELSBACHERPLATZ 2, 80333 MUENCHEN | ||||||||
Inventors:
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PCT International Classification Number | F 23 R 3/00 | ||||||||
PCT International Application Number | N/A | ||||||||
PCT International Filing date | |||||||||
PCT Conventions:
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