INFRARED RADIATOR

Abstract

An infrared radiator for the heat treatment of a material web includes an incandescent body with a flow-receiving surface to be impinged by a gas-air mixture that is supplied to the infrared radiator and to be heated by combustion of the gas-air mixture. The incandescent body is manufactured as a sheet material that is formed of a multiplicity of threads. The sheet material is manufactured by primary forming.

Claims

1-11. (canceled)

12. An infrared radiator for the heat treatment of a material web, the infrared radiator comprising: an incandescent body having a flow-receiving surface to be impinged by a gas-air mixture supplied to the infrared radiator and to be heated by a combustion of the gas-air mixture; said incandescent body being manufactured as a sheet material formed of a multiplicity of threads and said sheet material being manufactured by primary forming.

13. The infrared radiator according to claim 12, wherein said sheet material is a self-supporting sheet material.

14. The infrared radiator according to claim 12, wherein said threads of said sheet material are interconnected in an articulated manner at respective intersection points.

15. The infrared radiator according to claim 12, wherein said threads are formed spirally and said sheet material is a spiral braid with two directly adjacent threads respectively connected to one another in each case by meshing at intersection points.

16. The infrared radiator according to claim 12, wherein said sheet material is a woven fabric, comprising threads that serve as warp threads and that are interwoven at intersection points with threads that serve as weft threads, and wherein said threads have a wave-shaped outer contour.

17. The infrared radiator according to claim 16, wherein said woven fabric is a plain weave, with directly adjacent threads that serve as weft threads weaving alternately through threads that serve as warp threads, along different weaving paths.

18. The infrared radiator according to claim 12, wherein said threads are made of a comparatively flexurally rigid material.

19. The infrared radiator according to claim 18, wherein said threads are made of a ceramic.

20. The infrared radiator according to claim 12, wherein said flow-receiving surface is at least one delimiting side of said incandescent body.

21. The infrared radiator according to claim 12, further comprising a burner plate, and wherein said incandescent body is arranged behind said burner plate in a flow direction of the gas-air mixture.

22. The infrared radiator according to claim 21, wherein said incandescent body directly adjoins said burner plate viewed in the flow direction of the gas-air mixture.

23. The infrared radiator according to claim 12, wherein said incandescent body is manufactured from a plurality of layers of said sheet material arranged on top of one another.

Description

[0032] The invention is described in greater detail below with reference to the drawings, without restricting the invention's generality. The drawings show the following:

[0033] FIG. 1 a schematic, partially cut-away and not-to-scale representation of one embodiment of an infrared radiator;

[0034] FIG. 2 spatial representation of a possible embodiment of an incandescent body according to the invention;

[0035] FIG. 3 a highly schematized representation of a drying arrangement in a three-dimensional view according to one embodiment.

[0036] FIG. 1 shows an exemplary embodiment of the invention in a schematic, partially cut-away view through a plane that is perpendicular to the material web and parallel to the running direction (indicated by the arrow). The drawing shows an infrared radiator 1, which may be part of a drying arrangement 9. During normal operation, the infrared radiator 1 is arranged at a distance from the material web 8, for example above it. The radiator forms a burner that is arranged in a housing 11.1. This housing has, for example, a rear wall and a plurality of side walls. The rear wall is located on the side (rear side) of the infrared radiator 1 facing away from the material web 8. An opening 2 is provided in this wall, through which a fuel, for example gas and air (an ignitable, combustible gas-air mixture) may enter a mixing chamber 3. The corresponding supply lines outside the infrared radiator 1 are not shown in detail. The mixing chamber 3 is delimited on one side by a gas-permeable burner plate 4 and on the other side by the housing 11.1, here the rear wall thereof. The gas-air mixture flows into the burner plate 4 at a flow-receiving surface corresponding to the rear side of the infrared radiator 1 and passes through the gas-permeable burner plate 4, to be combusted. From there the mixture flows into a combustion chamber 5. This chamber is delimited or formed jointly by the burner plate 4 and an incandescent body 6. The gas-permeable burner plate 4 may be said to separate the mixing chamber 3 from the combustion chamber 5. In the latter chamber, the gas-air mixture ignites. The heat released heats the incandescent body 6 until this body begins to glow. As a result, the body emits infrared rays toward the material web 8 to be dried. Both the burner plate 4 and the incandescent body 6 have a slab-shaped or cuboidal outer contour. In principle, a different outer contour would be possible. In this case, the flow-receiving surface of the incandescent body 6 corresponds to the flow-receiving surface of the burner plate 4. In other words, the two flow-receiving surfaces are the same. They correspond in this case to the clear width of the housing 11.1 that accommodates both the burner plate 4 and the incandescent body 6.

[0037] Irrespective of the embodiment shown, the infrared radiator 1 with its incandescent body 6 faces the material web 8; in the case shown, it does so in such a way that the incandescent body 6 runs parallel thereto. However, this need not necessarily be the case. The infrared radiator 1 may also run at an angle thereto. As shown in FIG. 1, the burner plate 4 and the incandescent body 6 are connected in series, viewed in the flow direction of the gas-air mixture. The incandescent body 6 is arranged downstream of the burner plate 4.

[0038] According to the embodiment of FIG. 1, the incandescent body 6 is designed as a gas-permeable regular grid. This grid may be formed by at least one sheet material. This structure is made up of a multiplicity of threads that delimit the openings of the grid. Consequently, the gas-air mixture passing through the burner plate 4 may also flow through all openings of the incandescent body 6 (simultaneously).

[0039] The incandescent body 6 is arranged at a distance from the burner plate 4, viewed in the flow direction of the gas-air mixture or the combustion products thereof. In other words, the combustion chamber 5 is formed by the space jointly delimited by the burner plate 4 and the incandescent body 6. The burner plate 4 and incandescent body 6 are arranged parallel to each other with regard to their flow-receiving surfaces or delimiting sides.

[0040] Although this is not shown in the drawings, it would be possible for the incandescent body 6 to directly abut the burner plate 4. This means that both are arranged without distance from each other and preferably parallel to each other.

[0041] Irrespective of the embodiment shown, it would be conceivable in principle, for example to provide a plurality of layers of an incandescent body 6, or more precisely several layers of sheet materials, which could be arranged at a distance from the burner plate 4 in the flow direction of the gas-air mixture or the resulting combustion products.

[0042] FIG. 2 shows a spatial representation of a possible embodiment of the incandescent body 6 according to the invention as a sheet material. The incandescent body is made from a multiplicity of threads 15. The sheet material is designed, by way of example, as a spiral braid. For this purpose, the threads 15 are interlaced in the manner of spirals. The longitudinal central axes of the threads 15 run parallel to each other over the entire spatial extent of the resulting sheet material. Threads 15 that are directly adjacent to each other are connected to each other in such a way that the spirals thereof are screwed into one another. As a result, the threads 15 are respectively mounted to each other in an articulated manner at the shared intersection points. This interlocking of the threads 15 results in a loss-proof structure. In other words, if a part of a thread 15 breaks, it is held by the adjacent threads 15 at the intersection points. As a result, the probability that parts of the broken thread will fall onto the material web 8 is significantly minimized. Breakage may occur if the thread 15 is made of a ceramic.

[0043] Although not shown, the incandescent body 16 could also be manufactured in the manner of a woven fabric. In that case, two directly-adjacent threads that are designed as weft threads weave the same weaving path through the warp threads, perpendicular to the threads that act as warp threads.

[0044] For the production of such sheet materials, primary forming methods such as 3D printing may be used.

[0045] Irrespective of the embodiments shown, the increased surface area of the incandescent body 6 may considerably increase the radiation efficiency due to the wavy or spiral outer contour of the threads 15. This is achieved by increasing the surface area for the combustion of the gas-air mixture due to the selected outer contour, which results in a higher energy absorption from the combustion products of the gas-air mixture. This may also reduce the proportion of nitrogen oxides and carbon monoxide in the combustion products.

[0046] FIG. 3 shows a possible embodiment of a drying arrangement 11 according to the invention. This may be part of a machine for manufacturing or treating a material web. The drying arrangement 11 here is arranged behind a coating or binder section (not shown) of the machine, in the running direction of the material web 8. Within this section, a coating color or binder is applied to the material web 8. As a result of this application, the material web 8 absorbs moisture and must therefore be dried, or the binder must be cured. This is done in the drying arrangement 11.

[0047] The drying arrangement 11 comprises one or, as shown here, a plurality of infrared dryers 12, each of which respectively has a multiplicity of infrared radiators 1 that serve as surface radiators and are preferably arranged parallel to the material web 8. In addition, the drying arrangement 11 also has a plurality of air dryers 13. In the present case, an infrared dryer 12 is respectively downstream of an air dryer 13 when viewed in the running direction of the material web 8, and so forth. Such an infrared dryer 12 and air dryer 13 are respectively referred to as a combination dryer 14. Four combination dryers 14 are furnished, arranged one behind the other in the running direction of the material web 8 to be dried. These combination dryers are, in this case, arranged directly abutting one another. Consequently, when the material web 8 to be dried leaves a first combination dryer 14, it immediately reaches the following combination dryer 14 viewed in the running direction. All combination dryers 14 are set up in such a way that, viewed in the running direction of the material web, drying occurs by infrared radiation from the associated infrared dryer 12, then by convection through the corresponding air dryer 13, by heat radiation and so on alternatingly. As soon as the material web 8 has left the first combination dryer 14 as viewed in the running direction of the web, it is transferred to the second combination dryer 14. There in turn, as viewed in its running direction, the web is first dried by the corresponding infrared dryer 12 and then by the corresponding air dryer 13. In other words, an air dryer 13 assigned to the first combination dryer 14 is arranged between an infrared dryer 12 of a first combination dryer 14 in the running direction and an infrared dryer 12 of another combination dryer 14 immediately following it in the running directionviewed respectively in the running direction of the material web 8 through the drying arrangement 11. One could also say that the material web 8 is dried along the drying arrangement 11 alternatingly by heat radiation, then by convection, again in turn by heat radiation and so on.

[0048] The infrared dryer 12 of a respective combination dryer 14 may be designed as a gas-heated infrared dryer according to the invention. In this case, the infrared dryer 12 may comprise one or more infrared radiators 1 according to the invention (see FIGS. 1a and 1b). The combustion products (exhaust gases) that the infrared radiators 1 generate may then be extracted from the infrared dryer 12 via one or more suction nozzles 12.1 associated with the infrared dryer 12, only one of which is indicated here in a purely schematic manner. The at least one suction nozzle 12.1 may be arranged inside a housing that surrounds the infrared dryer 12.

[0049] The respective air dryer 13 may comprise one or more blowing nozzles 13.1, of which only one is shown here, likewise in a purely schematic manner. The at least one blowing nozzle 13.1 serves, among other things, to supply heated air to the material web 8 for drying. For this purpose, the at least one blowing nozzle 13.1 may be connected to a fresh air supply (not shown) in a flow-conducting manner. In addition, a flow-conducting connection may be furnished between the at least one suction nozzle 12.1 and the at least one blowing nozzle 13.1 of the same combination dryer 14. The thermal energy contained in the exhaust gas of the infrared dryer 12 may be used to heat the fresh air or to dry the material web 8 using the thermal energy of the exhaust gas of the respective infrared dryer 12.