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  Flame tube for a burner for hot gas generationUSPTO Application #: 20060093981Title: Flame tube for a burner for hot gas generation Abstract: A flame tube for a burner for hot gas generation has a hollow body which forms an at least partially enclosed combustion chamber. The hollow body has a first end which is designed for connection to a flame generation unit. The hollow body also has a lateral surface, on which at least one branch tube is arranged. The branch tube, on its outer side, is connected to an intermediate piece and the intermediate piece is secured to the lateral surface. (end of abstract) Agent: Klarquist Sparkman, LLP - Portland, OR, US Inventors: Erwin Merz, Michael Bohm USPTO Applicaton #: 20060093981 - Class: 431353000 (USPTO) Related Patent Categories: Combustion, Flame Holder Having Protective Flame Enclosing Or Flame Stabilizing Structure, Tubular Member Delineates Flame The Patent Description & Claims data below is from USPTO Patent Application 20060093981. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a burner for hot gas generation in mobile field kitchens, and more particularly to a flame tube for use in such a burner. Moreover, the invention also relates to a process of manufacturing such a flame tube. [0002] Mobile field kitchens are required in particular if a large number of people have to be catered remote from civilization for a prolonged period of time. Typical applications include military exercises or any other deployment of large numbers of troops, but also humanitarian work, for example disaster assistance in an earthquake zone. For these uses, the field kitchens have to be mobile and in particular robust. This means that it must be possible for the field kitchens to be transported, constructed and operated even under greatly fluctuating demands and difficult conditions. For example, it must be possible for them to be transported on a vehicle even on impassable terrain, which can lead to corresponding impacts and mechanical loads. Furthermore, the mobile field kitchens must work reliably both in hot environments, for example in the desert, and in very cold environments, for example in winter in mountainous areas. On the other hand, it is desirable for the mobile field kitchens, despite the abovementioned demands, to allow professional preparation of varied dishes for a large number of people. [0003] The present assignee markets field kitchens of this type and cooking modules for such applications. They generally use diesel or multi-fuel burners to heat the cooking zones. It must be possible for the burners to be operated with fuels of varying quality, and moreover the burners have to allow reliable operation under the boundary conditions mentioned above. Moreover, a high heating power is required in order to heat large-area cooking zones for the preparation of large quantities of dishes. Hitherto, for its mobile field kitchens and cooking zones, the assignee has used flame tube with a hollow body to which 15 branch tubes were welded. The branch tubes are used to discharge the hot gas (flue gas) generated in the hollow body, and they are arranged in such a way that the hot gas which flows out heats a surrounding volume of air and/or a hotplate, a grill, a water bath or the like. [0004] However, the flame tubes which have been used hitherto have a limited use or service life, in particular when employed under fluctuating, harsh conditions. It has been found that the hot gas which is passed through the branch tubes leads to the formation of scale or even complete dissolution of material around the branch tubes. After prolonged operation of the flame tubes which have been used hitherto, holes are formed around the branch tubes, and in some cases branch tubes actually fall into the interior of the flame tube. [0005] Furthermore, the flame tubes which have been used hitherto are relatively complex and correspondingly expensive to produce, since 15 branch tubes have to be individually welded to the lateral surface of the hollow body. To reduce the investment and operating costs of the field kitchens and cooking modules, there is a demand for a flame tube which allows a longer service life combined with lower production costs. [0006] DE 42 444 400 A1 discloses a burner with a flame tube, the lateral surface of which is studded with branch tubes. In this case, the branch tubes are not used to discharge flue gas from the combustion chamber of the hollow body, but rather, on the contrary, to return flue gas which has already escaped from the flame tube. This return of flue gas is known as recirculation and serves to reduce the emission of nitrogen oxides from the burner by the flue gas being returned to the combustion process. Unlike in the above-described burners marketed by the assignee, the branch tubes of the burner disclosed in DE 42 44 400 A1 therefore do not have the hot flue gas flowing through them from the inside outwards, but rather cooled flue gas flows back into the combustion chamber from the outside. Problems with the formation of scale and disappearance of material in the region of the branch tubes are not described in DE 42 44 400 A1. [0007] DE 42 32 181 A1 discloses another burner with a flame tube, which is provided with lateral branch tubes in the region of its lateral surface. In this case, the branch tubes only project into the interior of the hollow body, i.e. into the combustion chamber, and according to the description given in DE 42 32 181 A1 they serve as stabilizers for stabilizing the flame. This prior art likewise does not address problems relating to the formation of scale and/or removal of material in the region of the branch tubes. SUMMARY OF THE INVENTION [0008] In view of this background, it is an object of the present invention to provide a flame tube for a burner for hot gas generation, which, in mobile use under fluctuating conditions, allows a long service life. [0009] It is another object to provide a flame tube for a burner for hot gas generation, which can be produced at low cost. [0010] It is yet another object to provide a flame tube for a burner offering a good heat distribution for large-area cooking zones. [0011] According to one aspect of the invention, there is provided a flame tube for a burner comprising a flame generation unit, the flame tube having a hollow body forming an at least partially enclosed combustion chamber, and at least one branch tube connected to the hollow body, the hollow body having a first end designed for being connected to the flame generation unit, and a lateral surface on which the at least one branch tube is arranged, wherein the branch tube, on its outer side, is connected to an intermediate piece, and wherein the intermediate piece is secured to the lateral surface. [0012] According to another aspect of the invention, there is provided a method for producing a flame tube for a burner having a flame generation unit, the method comprising the steps of: providing a hollow body having a lateral surface for forming an at least partially enclosed combustion chamber, the hollow body having a first end designed for connection to the flame generation unit, and arranging at least one branch tube on the lateral surface, wherein the step of arranging includes a step of connecting the branch tube, on its outer side, to an intermediate piece, a step of securing the intermediate piece to the lateral surface. [0013] Preferably, the intermediate piece is welded to the lateral surface. [0014] The present invention is based on the idea of using an intermediate piece in order to secure the at least one branch tube--at least additionally--to the lateral surface of the hollow body. On account of the fact that the intermediate piece is connected to the branch tube on its outer side, the intermediate piece is not in direct contact with the hot flue gas in the interior of the hollow body. If any flue gas is able to reach the intermediate piece, which depends on the geometry of the branch tubes and the spatial conditions around the flame tube, it has already cooled compared to the temperatures of the hot flue gas in the interior of the hollow body. [0015] Furthermore, the very hot flue gas from the interior of the hollow body also does not flow past the intermediate piece with its high kinetic energy. Overall, therefore, the intermediate piece is exposed to lower energy loads than the branch tube itself. [0016] Tests and analyses carried out by the Assignee have shown that the problems encountered hitherto with the formation of scale and the removal of material occurred in particular in those regions where the branch tubes were hitherto welded to the lateral surface of the hollow body. One possible cause of this could be the "prior damage" to the material of the lateral surface and the branch tube, in particular caused by welding. [0017] Since the securing points of the new intermediate piece have been withdrawn from direct contact with the hot flue gas, significantly reduced formation of scale and--at least in the long-term tests carried out to date by the assignee--no significant disappearance of material are now found. In other words, the new flame tube, in which the branch tubes are secured to the lateral surface by way of said intermediate piece, has a significantly longer service life, the end of which is not yet foreseeable in the tests which the assignee is currently carrying out. [0018] Furthermore, the manufacturing costs are reduced by the use of the new intermediate pieces, since, on account of the new intermediate pieces, the branch tubes can be secured to the lateral surface more easily yet nevertheless with a high degree of stability. [0019] Finally, on account of the new intermediate pieces, the branch tubes can be very easily secured at various angles of inclination and at virtually any desired positions of the hollow body, so that the heat distribution of the new heating tube can be flexibly optimized. [0020] In a refinement of the invention, the branch tube and the intermediate piece are of two-part design, with the branch tube and the intermediate piece preferably being welded to one another. [0021] Alternatively, it would generally also be conceivable for the intermediate piece and the branch tube to be formed integrally (as a single piece), for example with the aid of a suitable casting mould. However, the preferred refinement allows greater flexibility of production and also allows the use of standardized components. [0022] It is preferable for the branch tube and intermediate piece--like the intermediate piece and lateral surface--to be welded together, since this joining process allows very robust flame tubes which are suitable for the intended application described in the introduction to be produced in a very inexpensive way. Continue reading... Full patent description for Flame tube for a burner for hot gas generation Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Flame tube for a burner for hot gas generation 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. Start now! - Receive info on patent apps like Flame tube for a burner for hot gas generation or other areas of interest. ### Previous Patent Application: Container candle Next Patent Application: Computer configured appliance for orthodontic correction of malocclusions Industry Class: Combustion ### FreshPatents.com Support Thank you for viewing the Flame tube for a burner for hot gas generation patent info. 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