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  Pore-type burner with silicon-carbide porous bodyUSPTO Application #: 20060035190Title: Pore-type burner with silicon-carbide porous body Abstract: A porous burner is configured for burning a fuel-air mixture and to generate a hot flue gas. The burner has a housing and porous material in the housing. The porous material is formed of silicone carbide that is resistant to high temperatures and facilitates combustion. The porous body in the housing is formed of a siliconized carbon fabric with a regular, uniform structure. The shape of the silicon carbide fabric deviates from a planar surface, for example with corrugations, and a plurality of such fabric sections are laid on top of one another. (end of abstract) Agent: Lerner And Greenberg, Pa - Hollywood, FL, US Inventors: Michael Hoetger, Walter Thiele USPTO Applicaton #: 20060035190 - Class: 431329000 (USPTO) Related Patent Categories: Combustion, Porous, Capillary, Particulate Or Sievelike Flame Holder, E.g., Radiant Surface Burner, Etc., Means Supplying Fuel For Passage Through The Flame Holding Structure, E.g., Radiant Surface Burner, Woven Screen Holds Flame The Patent Description & Claims data below is from USPTO Patent Application 20060035190. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This is a continuing application, under 35 U.S.C. .sctn. 120, of copending international application No. PCT/EP 2004/003968, filed Apr. 15, 2004, which designated the United States; this application also claims the priority, under 35 U.S.C. .sctn. 119, of German patent application No. 103 17 857.0, filed Apr. 16, 2003 and German patent application No. 10 2004 006 824.0, filed Feb. 11, 2004; the prior applications are herewith incorporated by reference in their entirety. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates to a pore-type burner for burning a fuel/air mixture for the purpose of generating a hot flue gas. The burner includes a housing in which a pore material consisting of porous, high-temperature-resistant silicon carbide (SiC) is provided for combustion. [0004] Such a pore-type burner is employed, for example, in order to apply a hot stream of flue gas to a steam superheater. The steam arising in the steam superheater has high temperatures and is under intense pressure. The energy stored in the steam can then be made usable in the form of mechanical or electrical energy, for example as a result of decompression in an expansion engine for the purpose of driving a generator. The hotter the steam and the higher the pressure, the better the efficiency of such machines. Correspondingly, it is necessary for the stream of flue gas to exhibit temperatures that are as high as possible. Typical temperatures lie within the range between 850.degree. C. and 1400.degree. C. [0005] The pore-type burners for generating a hot stream of flue gas differ, in particular, from a pure radiation burner in which only the radiant heat of the burner is utilized and the flue gas arising is drawn off as a secondary product via a chimney or an exhaust-air pipe. Such radiation burners are, for example, artificial open fires or radiation burners for the purpose of drying lacquer coatings. Although the radiant heat of a pore-type burner can also be utilized, the significant portion of the energy transferred to the steam-generator comes from the flue gas. [0006] A pore-type burner for the combustion of a fuel/oxidizing-agent mixture is known from German patent DE 199 39 951 C2. The pore-type burner is filled with globular filling materials. The size of the pores that arise is determined by the size of the filling materials. The prior art pore-type burner is designed in such a way that an excessive temperature in the reaction chamber is avoided by means of an additional cooling gas. [0007] German patent DE 195 27 583 C2 describes a pore-type burner, which contains porous material that exhibits spatially contiguous cavities which are formed from a packing consisting of heat-proof wire material, foil material or sheet-metal material. A defined flame zone forms in these cavities. The material is not suitable for high temperatures. [0008] Moreover, pore-type burners are known--for example, from U.S. Pat. No. 5,890,886--which are filled with a ceramic that is formed with a plurality of cavities. Other foam ceramics, metallic foams or metallic sponges are also known, from German published patent application DE 196 21 638 A1 for example. These foams or sponges have the disadvantage that they are expensive to manufacture. In addition, they are very sensitive to mechanical and thermal loads. They tear or crack in the event of excessive loading, resulting in diminished performance and increased emission of noxious substances. [0009] German published patent application DE 198 47 042 A1 describes a highly porous burner mat, which consists of metallic or ceramic fibers that are welded to one another in irregular structures. The mat is provided with holes, through which the gas flows. Regions of varying flow velocities arise, by virtue of which an irregular carpet of flame arises which lifts off from the surface of the mat. SUMMARY OF THE INVENTION [0010] It is accordingly an object of the invention to provide a porous burner with silicon-carbide porous body which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides a pore-type burner that exhibits uniform combustion and that has a pore structure which is capable of being directly influenced in the production process. [0011] With the foregoing and other objects in view there is provided, in accordance with the invention, a pore-type burner for burning a fuel/air mixture for generating a hot flue gas, comprising: [0012] a housing; [0013] a porous body with pore material formed of porous, high-temperature-resistant silicon carbide disposed in said housing, said pore material being formed of siliconized woven carbon fabric disposed in an ordered, regular structure. [0014] In other words, the objects of the invention are achieved by the porous body comprising siliconized woven carbon fabric that is/are disposed in an ordered, regular structure. The invention is based on the perception that the properties of a pore-type burner can be influenced if the pore structure is capable of being produced for a specific purpose. An interweaving of the hard and brittle material silicon carbide is not possible. However, by siliconizing a suitably shaped woven carbon fabric it is possible to create an appropriately configured woven-fabric structure consisting of SiC. The siliconized woven fabric is capable of being produced inexpensively. It withstands mechanical and thermal loads very well. The mesh width and planar shape of the woven fabric are just as individually adaptable as are its size and contours, so an optimization of the properties of the burners is possible when use is made of materials of such a type by way of a porous body for pore-type burners. [0015] In one configuration of the invention the woven fabric consisting of silicon carbide has a shape diverging from a plane surface. A plurality of pieces of woven fabric can then be arranged in layers on top of one another. In this way, a three-dimensional configuration is created with which the pore-type burner is capable of being filled, without additional spacers or the like. [0016] The woven fabric may be shaped in an undulating manner, i.e., with a rounded corrugation. But other shapes are also possible, such as a profile that is sawtooth-shaped or box-shaped in cross-section. Then, in order to obtain a small pore size, on the one hand the parameters of the woven fabric may be kept small, and on the other hand the wavy shape may then be composed of a plurality of small undulations. [0017] The woven fabric may consist of completely siliconized fibers. But for some applications it may also be sensible for the woven fabric to be partially siliconized and to contain a core consisting of pure carbon. [0018] In a particularly preferred configuration of the invention, the ordered structures are designed in such a way that zones of varying porosity are formed. In this case the porous body of the burner may be designed in two or more zones of varying pore size. The inlet-side part of the porous body then exhibits a smaller pore size than the outlet-side porous body. With this configuration the flame forms in the coarse-pored zone, whereas a mixing and preheating of the fuel/air mixture take place in the fine-pored zone. This results in a particularly low noxious-substance content of the flue gas in the course of combustion of the customary fuels such as natural gas, gasoline or such like. The pore size can be realized particularly well by virtue of the selected woven fabric and its arrangement--such as, for example, its stacking. [0019] In an alternative configuration of the invention the fine-pored part is produced from materials forming conventional pores, whereas the coarse-pored part consists of siliconized woven carbon fabric. The material of the fine-pored part is preferably poorly conducting, so that a transfer of heat out of the combustion zone into the premixing zone is avoided. In this way, a backfiring of the flames is prevented. [0020] The axes of curvature of the undulations of a piece of woven fabric may lie in a plane, and the pieces of woven fabric may be arranged above one another in such a manner that the projections of the wave normals onto such a plane defined by the axes of curvature extend perpendicular to one another. The wave normals then preferably each form an angle of approximately 45.degree. relative to the direction of flow of the flue gas. A wave normal here is the perpendicular to a wavefront; it lies in the plane defined by the axes of curvature. With this configuration of the invention the pore structure is formed from stacked undulating SiC mats. In this case the individual planes are arranged rotated by an angle of approximately 90.degree. in relation to one another. This arrangement is particularly favorable for the combustion behavior of the burner. The structure that is flowed through in such a way is designated as a static mixer. In the process, the fuel and the combustion air are mixed with one another in such a way that the fuel is burnt in a particularly low-emission manner and completely. [0021] The housing of the burner is preferably provided with an insulating layer. In this way, an undesirable convective transfer of heat through the housing into the periphery of the burner is avoided. Continue reading... Full patent description for Pore-type burner with silicon-carbide porous body Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Pore-type burner with silicon-carbide porous body patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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