Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
  • F23D14/12—Radiant burners
  • F23D14/16—Radiant burners using permeable blocks
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23D—BURNERS
  • F23D2203/00—Gaseous fuel burners
  • F23D2203/10—Flame diffusing means
  • F23D2203/106—Assemblies of different layers

Definitions

• Ceramic combustion carrier element for surface burner and method for its production
• the invention relates to a ceramic combustion carrier element, preferably in the form of a ceramic composite body in surface radiation burners for industrial conversion and heating processes in the temperature range up to in particular about 1300 ° C., and a process for its production.
• Radiant surface burners are used in various versions, in particular for rough heating and drying purposes in the infrared range and as low-emission combustion units in the heating and boiler range. Above all, the possibilities of low-pollutant operation at application temperatures up to 1000 ° C are used.
• Multi-flame surface burners are characterized by the fact that, starting from the burner surface, many individual flames are formed, which can combine to form a flame front in certain power ranges.
• stable perforated or slotted flame carrier elements are used to improve the service life compared to metallic flame carriers, as described, for example, in DE-A-4041 061, from which a ceramic combustion carrier element can be found according to the preamble of claim 1.
• metallic flame carriers as described, for example, in DE-A-4041 061
• the heat extraction remains relatively low.
• the nitrogen oxide formation is higher than in comparable quasi-flameless surface burners.
• the work area is further restricted by a higher CO and CxHy load.
• porous ceramics as described, for example, in EP-A-0 056 757.
• the binders, clay or bentonite used here, combined with the required flame retardancy, only allow a sufficient service life in cyclical operation if the temperature gradient across the layer thickness of the ceramic is low. Added to this is the described low pressure loss of the ceramic in the case of the cylinder shape closed on one side an expected irregularity of the flame distribution with increased energy output towards the closed head end.
• the quasi-flameless surface burners form a second group.
• this type of burner the flame root sits in a certain power range in the surface layer of the combustion carrier and makes it glow.
• the combustion temperature of the fuel-air mixtures passed through the flame carrier is lowered and the formation of NOx is significantly suppressed.
• Above a certain burner output and with a high excess of combustion air the flame also detaches from the surface in these burners and causes a deterioration in the exhaust gas hygiene.
• An essential form of this type of burner is based on radiation combustion elements made of ceramic fibers, which are preferably deposited on a metal sieve by vacuum shaping in connection with binders. Refinements of this form are e.g. in EP-A-0 382 674, EP-A-0 397 591; US-A-4 416 619; DE-A-3 311 953; US-A-3 179 156;
• the flame carrier solutions described in EP-A-0382 674 and EP-A-0 397 591 allow a very small control range to be expected.
• the thick fiber layer crosslinked according to the description with alumina coating is mechanically susceptible, in particular sensitive to any handling, to vibrations and is increasingly prone to erosion during the thermal aging process.
• the closed shape of the burner head means that a jamming effect with uneven distribution of the flame on the ceramic jacket and thus a deterioration in the exhaust gas hygiene and increased erosion of fibers in this area (formation of hot spots) can be expected.
• the binder structure with the desired gamma and theta phases of the AI2O3 as the main binder constituent ie described in TJS-A-4 416 619 and DE-A-3 311 953, is used both for the heat treatment for removing the pore former and for the subsequent one
• Operating temperature of the fiber ceramics limits that are around 1100 ° C.
• the gas chemical effect is less important, unless the large surface area of the gamma and theta phases is required in connection with catalytic additives.
• the embrittlement of the surface layer due to the phase transition of the AI2O3 into the alpha phase above approximately 982.2 ° C. is important here (see DE-A-3 311 953).
• the measures for pre-notching the surface specifically proposed in DE-A-3 311 953 and US-A-4 416 619 are intended to prevent longer cracks and larger formwork, but in the long term are themselves preferred areas for crack growth and erosion.
• a further disadvantage of this ceramic is the tendency for selective erosion at weak points and in areas of increased pressure, in particular in the head region of cylinders closed on one side.
• the onset of hot spot formation progresses with thermal aging and worsens the otherwise very favorable exhaust gas hygiene of this type of burner with regard to NOx, CO and CxHy loads and has a negative influence on the burner start behavior.
• Radiation burner based on ceramic fiber fabrics as a flame carrier on a porous metal carrier as in US-A-4 599 066; US-A-4 721 456 or e.g. described in DE-A-3 504 601, try to avoid the disadvantages of the vacuum-shaped fiber ceramic in terms of strength and long-term stability.
• US-A-4,721,456 includes metallic fasteners that limit the operating temperature and do not prevent possible changes in the pore shape depending on pressure and performance over a longer operating period and cycles.
• EP 0 187 508 A3 relates to a combustion carrier element which consists of a porous combustion body which is formed by shaping and sintering a starting material from ceramic powder, binder and inorganic fibers and which, in addition to its porosity, has a multiplicity of preferably drilled through holes, see in particular p 5, last paragraph to p. 7, first paragraph
• EP-A-0410569 AI relates to a plate-shaped porous combustion body which is supported by a metal sieve and consists of two blocks extending transversely to the direction of passage, of which the second block has a porosity with larger through openings. An explanation of the actual flow resistance cannot be found.
• the second block can be coated or impregnated with metal oxide, see col. 7, lines 45 to 55.
• EP-A-0 530 630 AI discloses a porous combustion body with several zones in which the structure or porosity is refined from the inside out. An explanation of the actual flow resistance cannot be found in this publication either.
• porous combustion body From AU-B-25742/67 a porous combustion body can be found which, in order to avoid a flashback, has a porous layer which is formed by applying a slurry containing aluminum powder and fibers.
• FR-A-2 222 329 relates to a porous combustion body with different flow resistance, so that a pilot flame results during operation.
• WO-A-84 04376 describes a porous combustion body containing fibers, the outer surface of which is sealed, see in particular p. 5, last paragraph.
• US-A-4 189 294 relates to flameless combustion in a catalyst zone and is to be considered as the more distant prior art.
• US-A-4 889 481 a plate-shaped or sleeve-shaped porous combustion body made of ceramic material is described, wherein the body has two layers of different porosity, see Col. 4, line 22. Furthermore, the outer end face of the first layer and in essentially all surfaces of the second layer have a ceramic coating, see abstract.
• a molded body made of porous ceramic material consisting of a foamable starting material with a mixture of alkali silicates, alkali metal minates and ceramic particles. This is a porous body for various purposes, including kilns.
• US-A-4 643 667 describes a porous combustion body consisting of two layers, the first layer having a low and the second layer having a higher thermal conductivity.
• the two layers are of different porosity, see column 5, line 25 and the following.
• porous combustion body which consists of essentially spherical particles, the size of the particles increasing from the inside out.
• the particles are baked together (sintered), see column 4, last paragraph, and they can have a catalytic coating.
• a porous combustion body which consists of spherical ceramic particles which are connected to one another by a binder to form a solid body.
• US-A-4 039480 describes a process for producing substantially spherical pelets and their use as a catalyst.
• the spherical pelets contain a flammable material and they are coated on the outside with a ceramic powder. Due to this coating, they can be sintered together under the influence of heat, whereby the combustible material is burned out and hollow ceramic balls are formed.
• the ceramic can be an aluminosilicate such as mullite.
• the object of the invention is to create a combustion carrier element which, while ensuring a high level of corrosion resistance, stability and service life, on the one hand has a good flow through the fuel and on the other hand has a good and trouble-free combustion even at high temperatures, especially up to about 1300 ° C.
• the invention is also based on the object of achieving a high combustion quality with minimal NOx formation and almost complete avoidance of CO and CxHy formation in a sufficient output range of at least 1: 2.5.
• the invention is further based on the object of creating a combustion carrier element which can be produced simply and inexpensively with satisfactory porosity and thermal and mechanical stability.
• the invention is based on the object of designing a combustion carrier element in such a way that a specific, in particular uniform, flow velocity profile or flame distribution arises on its combustion surface.
• the combustion carrier element according to the invention according to claim 1 has a porous, spherical or hollow spherical bulk ceramic.
• a porous, spherical or hollow spherical bulk ceramic can be produced simply and inexpensively and, with satisfactory strength, also leads to an advantageous porosity and a trouble-free and uniform gas flow.
• Combustion carrier element can serve as a post-mixer and mixture distributor for the fuel-air mixture flowing through. Due to the existing porous bulk ceramic, the combustion carrier element has sufficient flow resistance to prevent a flashback. In addition, the porosity is of satisfactory uniformity, which leads to a largely uniform flow velocity profile. It is furthermore advantageous to preburn the ceramic according to the invention, at least up to a temperature such that it has sufficient strength to be able to function as a flame holder with a long service life.
• the combustion carrier element according to claim 1 and also the multilayer ceramic combustion carrier element according to claim 9 are suitable both for multi-flame surface burners and for quasi-flameless surface burners, the combustion carrier element being particularly suitable for a quasi-flameless surface burner, in particular because the second or one Another layer arranged on the downstream side favors the mounting of the flame root in its surface layer. Due to the design of this combustion carrier element as a composite part, the combustion carrier element according to the invention is not only of great thermal but also mechanical stability.
• the embodiment according to the invention improves the gas outflow, the risk of flashbacks being eliminated or at least largely reduced.
• the influencing of the structural layer structure which can be achieved by the features according to the invention can be achieved by combining a gas propulsion process with a burnout process, an open macro and micropore spectrum in the range of equivalent pore diameters of> 0 to approx. 1 mm, which is favorable in terms of combustion technology, being achieved in the layers and at the same time one multidirectional cross-linking (reinforcement) of the pile is brought about by fiber materials, which have a very positive influence on the thermal shock resistance of the layers.
• the refinements according to the invention are suitable both for a disk-shaped shape and for a sleeve-shaped or pot-shaped shape of the combustion carrier element.
• the method according to the invention according to claim 30 not only leads to the advantages already mentioned with regard to claim 1, but it also enables simple and inexpensive production of the combustion carrier element, furthermore it favors its properties with regard to porosity, strength, heat radiation and service life.
• the invention provides a flame-retarding ceramic for a quasi-flameless gas radiant burner, which preferably works according to the premixing principle, which preferably enables heat generation and heat treatment processes up to 1300 ° C. in connection with exhaust gas post-combustion, and additionally the use of hydrocarbon-containing exhaust gases as fuel directly or at lower concentration than combustion air, which is then a common fuel gas, e.g. Natural gas, which is to be added, is permitted and, with a special choice of materials, can also safely thermally re-burn halogen-containing components in the exhaust gas.
• a common fuel gas e.g. Natural gas, which is to be added
• the invention also makes corrosion-sensitive, delicate, metallic construction elements, such as e.g. Screen mesh, fine perforated mesh, fine perforated plates and metal fiber fleeces avoided.
• the subclaims contain further training features which further improve the solution features according to the invention and lead to conditions for better utilization of the advantages achievable by the invention.
• combustion carrier elements according to the invention and the method according to the invention are preferably suitable for a multi-layer composite ceramic, in particular with two or three layers.
• FIGS. 2 and 3 modified configurations of the combustion carrier element according to claim 1,
• FIG. 4 shows a sleeve-shaped combustion carrier element according to the invention in axial section, which is closed at its downstream end
• 5 shows a sleeve-shaped combustion carrier element according to the invention in a modified configuration.
• the combustion carrier element E consists of three layers 1, 2 and 3, which lie transversely to one another with respect to the direction of flow and form a composite body.
• the upstream fuel-air mixture flow is designated by 4.
• the fuel-air mixture on the downstream combustion surface 5 of the third layer 3 (or the second layer 2 in the case of a two-layer composite body) forms a flame front 6, which is only indicated in FIGS. 1 and 4 and whose outflow velocity profile is uniform, such as the large number of small arrows in the flame front 6 illustrates.
• a tubular holder 7 can be used to hold the combustion carrier element E, which holder surrounds the combustion carrier element E on its circumference.
• the combustion carrier element E is preferably tapered in the form of a step or conically towards the outflow side, as a result of which a step surface 8 is formed which can be engaged by the holder 7 in order to prevent the combustion carrier element from slipping out of the holder 7 unintentionally.
• the fuel-air mixture 4 is supplied to the combustion carrier element E on the upstream side, e.g. in the holder 7, an increased dynamic pressure occurs in the center of the flow 4, which leads to an increased outflow velocity profile on the outflow side without special guiding devices.
• the flow resistance of the combustion carrier element E is made larger in the center than in the area surrounding the center, the degree of gas permeability increasing radially progressively. This can e.g. can be achieved by a different porosity.
• this different gas permeability is created by a thickness of the layer 1 that is progressive towards the center.
• the layer 1 is thickened in the center on the upstream side, and preferably in the sense of a curvature 9.
• the exemplary embodiment according to FIG 2 and 3 are dimensioned essentially the same thickness and adapted to the thickening of the layer 1, so that according to FIGS. 1 and 2, except for the edge of the layer 3, the layers 2 and 3 are flat and curved according to FIG. 3.
• the cavity 11 is designed to be convergent, in particular conical, towards the outflow side, so that with a cylindrical shape of the outer surface 12 of the first layer 1, a thickness diverging towards the outflow side d for the first layer 1.
• the above-described flow pressure in the front region of the cavity 11 likewise leads to an increased outflow velocity profile on the end face 13 flattened with rounded corners (FIG. 4) or on the particular one
• the end layer 13 (FIG. 5) of the combustion carrier element E is rounded in a hemispherical shape.
• the first layer 1 can have a thickness d1 which is larger than the thickness d in the region of the first region which adjoins the rear side Layer 1.
• the shape of the front end of the cavity 11 is adapted to the outer shape of the first layer 1.
• such a change in flow, in particular reduction, can also be achieved by a compressed region 14 of the first layer 1 in the front end region.
• a compressed area 14 can be created by a more or less dense application or coating with a suitable means.
• Such an agent can not only coat layer 1, but can also penetrate into layer 1. 4 and 5, such a compressed region 14 is in each case created on the outside on the layer 1 in the center region of the combustion carrier element E and is covered by the second layer 2.
• Such a coating or compression need not be completely sealed, it can also have a lower porosity or gas permeability than the first layer 1.
• This compressed area 14a extends as far as the second layer 2 or possibly also the third layer 3.
• the compressed area 14a on the back of the first layer 1 preferably also extends radially inward by a few millimeters.
• This radial section is designated 14b.
• a corresponding radial section 14c can also be arranged on the outflow side of the first layer 1, as shown in particular in FIG. 3. In such a case, the second layer 2 or the third layer 3 can cover the section 14c.
• the upstream holding area in the case of a sleeve-shaped layer 1 is also provided with a compressed area 14a, as shown in FIGS. 4 and 5.
• the sleeve-shaped layer 1 projects over the layer 2 or possibly also layer 3 on the upstream side by a section 15 required for holding, the outer surface of this section 15 being sealed in the sense of the compressed region 14a.
• the compressed region 14a preferably extends not only with a radial section 14b on the downstream end face of the first layer 1, but also with a section 14d on the inner wall of the cavity 11.
• a previously described seal 14 or 14a is preferably a slip coating.
• Preferred layer thicknesses for layer 1 are between approximately 10 and 50 mm, for the second layer 2 between approximately 1 and 4 mm and for the third layer 3 between approximately 1 and 4 mm, depending on the type of fuel, output, design and form of the fuel / air Mixture.
• the particularly preferred layer thickness for the second layer 2 is 1.5 mm - 2.5 mm and for the third layer 3 1 to 2 mm.
• the first layer 1 is preferably made of hollow spherical mullite ceramic. Using similar aggregate sizes, grain sizes, binder quantities and types, the manufacture can also be carried out with other hollow sphere materials in the high temperature range, such as corundum, zirconium oxide, titanium oxide, cordierite, etc.
• a mullite ceramic with the following composition has proven to be advantageous:
• Aggregate hollow spherical mullite with aggregate sizes of 0.5 - 5 mm, preferably 0.7 - 1, 5 mm
• Al2 ⁇ 3 content 72-77% by weight; preferably: 72.9% by weight SiO 2 content: 22-27% by weight; preferably: 24.9% by weight
• Binder Mixed binder based on alumina, pyrogenic silica and silica sol with the main components:
• Al2 ⁇ 3 content 72-80% by weight; preferably: 72 - 75%
• SiO 2 content 19-27% by weight; preferably: 23 - 26%
• Portion in ceramics 5 - 15% by weight, preferably: 7 - 10% by weight
• a strengthening agent for example up to 1% by weight of monoaluminum phosphate, preferably in a liquid binder, can be added to the binder. 13
• Additive / filler fine mullite grain with a grain size of 0.15 mm, preferably 0-0.08 mm, e.g. as enamel mullite quality with the
• Al2 ⁇ 3 content approx. 76% by weight
• SiO 2 content approx. 23% by weight
• the binder is stirred, starting with the mixture of the dry components, with the addition of the silica sol until all components are evenly distributed.
• the water is introduced through the silica sol, possibly also through the phosphate liquid binder and, in an expanded version, through a commercially available organic thickener, e.g. Methyl cellulose, carboxymethyl cellulose or hydroxyethyl cellulose, which can optionally be added to improve the processing consistency.
• the mixed binder is continuously added to the dry premixed aggregates and additives (fillers) while the mixing process is continued and mixed until a uniform consistency is achieved.
• the molding is then preferably carried out by shaking into an appropriate mold, stamping or isostatic pressing.
• the green body is dried for about two hours to about 180 ° C.
• Sealing areas 14 or 14a, 14b, 14c which are desired in terms of flow technology are covered or penetrated with a slip coating made of binder, mixed with an increased proportion of filler. Then the firing process takes place between about 1200 and 1600 ° C cooking temperature.
• the second layer 2 explained at the beginning with regard to its functional effect is preferably described according to the invention using the example of a solid-reinforced mullite fiber aggregate.
• a solid-reinforced mullite fiber aggregate Refinements based on others Crystalline (single and / or polycrystalline) high-temperature fibers or fiber mixtures with application temperatures approximately above 1500 ° C, such as Al2 ⁇ 3 fibers with
• the fiber diameter should preferably be in a narrow spectrum above 3 / ⁇ m. Fibers with a diameter of 10 ⁇ m and larger are particularly preferred.
• the fiber length should be in the range 0-5 mm, preferably 0-3 mm.
• Proportion in the starting material 40-80% by weight, preferably 50-70% by weight
• Inorganic binders preferably mixed binders, matched to the fiber and filler quality from colloidal solutions / precursors of Al2O3, SiO2 and ZrO2, eg mixed binders made of colloidal Al2O3 and colloidal SiO2 adjusted to a content of main components of 15
• an addition of clay in the order of 0-30% by weight can be added to the above-mentioned ceramic starting material.
• a burnout material is added to the ceramic starting material, preferably in a fibrous or splintered form with a diameter of less than about 0.5 mm and a length of less than or equal to about 3 mm, e.g. in the form of synthetic fiber cutting, natural fiber cutting or wood flour.
• the proportion added is: 30-70% by weight (based on the anhydrous starting material).
• a commercially available thickener preferably in the form of a cellulose, e.g. in the quality of methyl cellulose, carboxymethyl cellulose or hydroxyethyl cellulose with a proportion of 0.2-5% by weight of dry substance (based on the dry starting material) in 1% aqueous solution.
• a gas-developing substance is added to the ceramic starting material, which in connection with an increase in temperature causes a blowing reaction in the layer with corresponding porosity.
• the relative proportion is 10-30% by weight (reactive substance, based on the anhydrous starting material).
• the elimination of oxygen in the thermal / catalytic decomposition of H2O2 can advantageously be used, preferably about 10-30 percent aqueous solutions being used.
• the second layer 2 can be produced, for example, by wet dispersing a fiber section of the length 3 mm of the aforementioned mullite fiber in order to gently disintegrate the fibers.
• the combustible aggregate e.g. as wood flour (sieve passage 0.5 mm) with an elongated, splintered shape, added and stirred again until evenly distributed.
• the inorganic filler e.g. Mullitfeinkom
• the binder e.g. the Al2 ⁇ 3_Si ⁇ 2 mixed binder with 77% AI2O3 and 23% Si ⁇ 2, as well as the organic thickener, e.g.
• Hydroxyethyl cellulose in 1 percent aqueous solution added and evenly distributed with stirring. The mass is kept below 20 ° C if necessary by cooling the individual components.
• gas evolving substance e.g. H2O2
• the gas evolving substance e.g. H2O2 in 10% or preferably 30% aqueous solution, added and evenly distributed in the mass. The mass is raised by adding water
• the ceramic is at
• the dried second layer 2 is preferably sanded with which the layer thickness is adjusted, e.g. 2 mm. Sanding after drying is also advantageous for the first layer 1.
• the third layer 3 explained at the beginning with regard to its functional effect as a flame carrier layer is explained here using the example of a mullite fiber pile with a modified structure.
• the second one Layer 2 described geometric requirements for the fiber materials in terms of diameter and length also apply to the third layer 3.
• the ceramic starting material from the third layer 3 is formed by
• Proportion in the starting material 20-60% by weight, preferably 30-50% by weight (based on anhydrous substance)
• Proportion in the starting material 5-40% by weight, preferably 10-30% by weight (based on anhydrous substance)
• - inorganic binders preferably mixed binders, matched to the fiber and filler quality from colloidal solutions / precursors of Al2O3, SiO2 and Z1O2, for example mixed binders from colloidal A1 2 ° 3 ' si0 2 ie * ⁇ layer 2
• Proportion in the starting material 5 - 30% by weight, preferably 10 - 20% by weight (based on anhydrous substance)
• - radiation-active inorganic aggregate material with a preferred grain size of 0-0.15 mm, e.g. SiC, Cr2 ⁇ 3, Cr2 ⁇ 3 spinels, Fe2 ⁇ 3 spinels etc.
• the aforementioned ceramic starting material can be added in the order of clay
• a burnout material preferably in a fibrous or splintered form, is mixed into the ceramic starting material in the geometry and material configuration described for layer 2.
• the proportion added is: 30-50% by weight
• the ceramic starting material is also a commercially available thickener of the quality described for layer 2, with a proportion of
• a gas-developing substance according to the description of layer 2 is also added to the ceramic starting material, the reactive portion
• Layer 3 is produced in an analogous manner to layer 2.
• the same type and size of the burnout material is added in the basic version.
• melt mullite fine grain and SiC fine grain are premixed as solid additives in the weight percentages described for layer 3 and added to the mass and incorporated.
• the above-mentioned Al2O3-SiO2 binder and then the thickener are then added in modified proportions by weight and uniformly 95/03511
• a surface formed by sanding after drying is also advantageous for the third layer 3. This improves the gas flow and the layer thickness can also be adjusted.
• the quality of the burnout material can be varied, e.g. Synthetic fiber section with a length of approximately 3 mm and a diameter of less than approximately 0.5 mm.
• the mixed binder can be varied, for example by adding a colloidal solution / precursor of Z1 2, which can partially or completely replace the colloidal SiO 2 solution.
• the ceramic After completion of the driving process and drying, preferably about twelve hours at about 40 ° C, the ceramic is fired between about 1200 ° C and 1600 ° C depending on the material structure of the layers.
• the layer thickness is reproducibly set, for example to about 2 mm, by sanding the outer layer 3 or possibly also second layer 2.
• the material selection is determined by the specific requirements of the respective application process, in particular the exhaust gas components in the case of the treatment of gaseous waste products by thermal oxidation. Form and performance requirements have a decisive influence on the geometry. With knowledge of the combustion mechanism, the resistances can be controlled by the three- or possibly also multi-layer structure and reduced by air analog flow tests so that the flame root can be kept in the ceramic of the outer layer over a wide power range and a wide air ratio and thus a NOx -Low and almost CxHy- and C ⁇ -free product leaves the burning surface.
• the first layer 1 is flowed through and flowed through by the fuel-air mixture 4. It distributes the mixture as evenly as possible over the focal surface 5 according to the flow resistance and causes a slight Preheating and postmixing.
• preheating is intensified and the flow profile is further homogenized.
• the mixture is brought up to the reaction temperature.
• the actual flame sits as a front in or directly on layer 3 and makes it glow.
• the outflowing exhaust gases are illustrated by reference number 6.
• Such a ceramic is held in a gastight manner via a suitable media feed including attachment 7.
• the combustible mixture supplied in the ceramic is ignited by a suitable device on the surface, the combustion exhaust gases are fed to a combustion chamber and, depending on the process, more or less intensive heat removal is realized.

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• General Engineering & Computer Science (AREA)
• Gas Burners (AREA)
• Compositions Of Oxide Ceramics (AREA)

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• 1993
  • 1993-07-22 DE DE4324644A patent/DE4324644A1/de not_active Withdrawn
• 1994
  • 1994-07-22 AT AT94925377T patent/ATE178397T1/de not_active IP Right Cessation
  • 1994-07-22 US US08/592,429 patent/US5749721A/en not_active Expired - Fee Related
  • 1994-07-22 DE DE59408046T patent/DE59408046D1/de not_active Expired - Fee Related
  • 1994-07-22 EP EP94925377A patent/EP0708901B1/fr not_active Expired - Lifetime
  • 1994-07-22 WO PCT/EP1994/002419 patent/WO1995003511A1/fr not_active Ceased

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