Hot air tunnel with heat recovery

Abstract

Hot air tunnel (1) for heating objects in the interior (3) of the hot air tunnel (1) by means of hot air, wherein the hot air tunnel (1) has an outer surface (4) which surrounds the interior of the hot air tunnel (1), and wherein the hot air tunnel (1) has an air supply duct (2) on its outer surface (4) through which air supply (5) can be supplied to the interior (3) of the hot air tunnel (1), so that air supply (5) in the air supply duct (2) can be preheated by heat which passes from the interior (3) of the hot air tunnel (1) through the outer surface (4) into the air supply duct (2), characterized in that the air supply duct (2) encloses the outer surface (4) of the hot air tunnel (1) in an annular or ring-like manner.

Description

State of the art

[0001] This invention relates to a hot air tunnel with which objects can be heated using hot air, wherein an interior of the hot air tunnel is surrounded by an outer surface. Furthermore, the invention relates to a filling and / or packaging machine. Furthermore, the invention relates to a method for heating supply air for the interior of a hot air tunnel. One application of such a hot air tunnel is the sterilization of objects.

[0002] The outer surface of the hot air tunnel refers to the outer surface of one or more components that enclose the interior of the hot air tunnel, where the objects are heated. This outer surface can itself be enclosed by additional components, such as a housing or a casing, which in turn have their own outer surface. It is conceivable that the invention could also be applied to this outer surface.

[0003] According to the generic US 2012 / 0216417 A1, as a prior art embodiment, the hot air used inside the hot air tunnel to heat the objects is largely recirculated instead of being replaced with fresh air. In this embodiment, the hot air tunnel has several adjacent parts with different temperatures. Hot air losses can occur when hot air flows from a warmer part into a neighboring, cooler part or flows out of the hot air tunnel. This escaped air portion must also be replaced with fresh air, and this fresh air must be heated to the desired air temperature for the heating channel. This requires a not inconsiderable energy expenditure.

[0004] EP 2 132 511 B1 discloses a device for drying molded parts. Disclosure of the invention

[0005] The subject matter of the invention is a hot air tunnel having the features of patent claim 1.

[0006] The subclaims show preferred developments of the invention.

[0007] In one embodiment of the hot air tunnel, a cladding or housing of the hot air tunnel, which at least partially surrounds the outer surface of the hot air tunnel, and / or a holding device, by which the hot air tunnel is at least partially supported, forms at least part of the supply air duct. In particular, the supply air duct is thus formed partly by the outer surface of the hot air tunnel and partly by an inner surface of a holding device and / or a cladding of the hot air tunnel. In this way, the holding device and / or the cladding or housing of the hot air tunnel are used twice, namely as part of the supply air duct and as a holder or protection for the hot air tunnel. This is cost-effective. The supply air duct can be an integral part of the machine structure that surrounds the hot air tunnel.Heat escaping from the interior of the hot air tunnel through its outer surface can thus heat air inside the supply air duct.

[0008] In a further embodiment of the hot air tunnel, the supply air duct is sealed from the surroundings of the cladding and / or the support device, as well as from the interior of the hot air tunnel. This prevents unwanted heat loss due to the escape of already heated supply air from the supply air duct or the escape of hot air from the interior of the hot air tunnel into the supply air duct.

[0009] In a further embodiment of the hot air tunnel, it is provided with a fan that can convey supply air through the supply air duct into the interior of the hot air tunnel. Furthermore, an air filter is arranged in the air duct, which is positioned in particular at an inlet to the supply air duct. If the fan is arranged downstream of the air filter, it creates a negative pressure between the air filter and the fan. The section of the outer surface of the hot air tunnel that forms part of the supply air duct thus creates a negative pressure that ensures that air can only pass from the interior of the hot air tunnel into the supply air duct, but not vice versa. In this way, it can be prevented that particles, harmful substances, bacteria, or the like are introduced into the interior of the hot air tunnel with air that could otherwise flow from the supply air duct into the interior of the hot air tunnel.Before the supply air is used to heat the objects, the supply air is typically filtered so that particles, harmful substances, bacteria or the like are removed from the supply air before the supply air comes into contact with the objects.

[0010] In another embodiment of the hot air tunnel, it has a hot section and a cooling section, each with its own supply air. The temperature in the hot section is higher than the temperature in the cooling section. The supply air duct preferably supplies the hot section with supply air, since the supply air for the cooling section is typically cooled rather than preheated.

[0011] According to the invention, the supply air duct encloses the outer surface of the hot air tunnel in a ring-shaped or ring-like manner. The supply air duct can partially enclose the outer surface, similar to an open ring or the like. Preferably, however, the supply air duct encloses the outer surface of the hot air tunnel completely or at least for the most part. If the hot air tunnel has a hot part and a cooling part, in one variant, only the hot part is largely or completely enclosed by the supply air duct. The higher temperatures of the hot part can preheat the supply air to higher temperatures. By covering warm parts of the outer surface of the hot air tunnel as comprehensively as possible, as much of the heat penetrating the outer surface as possible from the interior of the hot air tunnel can be absorbed into the supply air, thus optimizing the energy efficiency of the hot air tunnel.

[0012] In another embodiment of the hot air tunnel, heat transfer through the outer surface of the hot air tunnel is reduced by thermal insulation. This is particularly proposed for the area of a hot part, provided the hot air tunnel has a hot part. This has the advantage that less heat escapes from the interior of the hot air tunnel, which leads to a lower temperature in the supply air duct compared to a hot air tunnel without insulation. This, in turn, has the advantage that materials with lower temperature resistance can be used here.

[0013] In a further aspect of the invention, a filling and / or packaging machine is proposed which has a hot air tunnel according to one of the embodiments described above.

[0014] In a further aspect of the invention, a method for heating supply air with the features of claim 9 is proposed.

[0015] In one embodiment of the method, a negative pressure is generated in the supply air duct by a fan drawing supply air into the supply air duct against an air filter in or on the supply air duct. This results in the advantages described above with respect to the corresponding embodiment of the hot air tunnel. Drawings

[0016] Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings. In the drawings: Fig. 1 a schematic representation of a cross section through a hot air tunnel according to the invention in a first embodiment, Fig. 2 a cross-section through a second embodiment of the hot air tunnel according to the invention shown in more detail and Fig. 3 a schematic perspective view of a third embodiment of the hot air tunnel according to the invention with three parts. Embodiment of the invention

[0017] Fig. 1 schematically shows a cross-section through a first embodiment of a hot air tunnel according to the invention, wherein the cross-section is located at a point where it intersects the supply air duct 2. Deviating from the rectangular shape of the cross-section of the hot air tunnel 1, this can also have other shapes, such as a circular shape. This also applies to other embodiments. The hot air tunnel 1 has an interior 3 into which objects to be heated can be placed. There, they are brought to a desired temperature by hot air. The interior 3 of the hot air tunnel 1 is enclosed by a boundary 13 having an outer surface 4. Due to a temperature difference between the interior 3 of the hot air tunnel 1 and the surroundings of the outer surface 4, heat 7 from the interior 3 of the hot air tunnel 1 penetrates through the boundary 13 and the outer surface 4.The supply air duct 2 is delimited on one of its sides by the outer surface 4. The supply air duct 2 is further delimited by a duct outer side 9, which can also be part of a frame or a holder of the hot air tunnel 1 or a panel or a housing thereof. The boundary 13 of the interior 3 of the hot air tunnel 1 is preferably insulated with an insulating material (not separately shown). The passage of heat 7 is thereby reduced. The boundary 13 has a supply air inlet opening 6, through which the interior 3 of the hot air tunnel 1 is connected to the interior of the supply air duct 2. A fan (not shown) can be arranged in the interior 3 of the hot air tunnel 1, with which supply air 5 can be sucked into the interior 3. Alternatively, such a fan can also be arranged in the supply air duct 2. The duct outer side 9 has an opening 14 to its surroundings. An air filter 8 can be arranged in this opening, as shown.The air filter 8 can alternatively be arranged inside the supply air duct 2. Supply air is drawn into the supply air duct through the opening 14. Alternatively, a fan (not shown) can be provided to blow supply air through the air filter 8 into the supply air duct 2. However, if the supply air 5 is drawn in, a negative pressure forms between the air filter 8 and the suction fan, which surrounds the outer surface 4 of the interior 3 of the hot air tunnel 1 at the location of the supply air duct 2. Due to the higher pressure in the interior 3 of the hot air tunnel 1, no supply air 5 can pass from the supply air duct 2 into the interior 3 of the hot air tunnel 1. The supply air 5 flowing through the supply air duct 2 is heated by the heat 7 and thus absorbs heat loss from the interior 3 of the hot air tunnel 1. This improves the energy efficiency of the hot air tunnel 1.If, as shown, it is a supply air duct 2 that encloses the outer surface 4 of the interior 3 of the hot air tunnel 1 in a ring shape, a partition 15 is arranged inside the supply air duct 2 between the opening 14 of the duct exterior 9 and the supply air opening 6 at the boundary 13 of the interior 3 of the hot air tunnel 1, which partition wall enables a defined guidance of the supply air 5 along the outer surface 4 of the interior 3 of the hot air tunnel 1. This ensures that the supply air 5 has to pass through the entire supply air duct 2 and that the heat 7 can be dissipated across the entire outer surface 4, which forms part of the supply air duct 2.

[0018] Fig. 2 shows a further embodiment of the hot air tunnel 1 in a cross-section through the supply air duct 2. The supply air duct 2 is constructed as an integral component of the surrounding machine structure (frame, cladding), which allows heat to be recovered and thus energy to be saved. The supply air duct 2 is typically a sealed machine guard in an area of a hot part 11 of the hot air tunnel 1, with the supply air duct 2 enclosing the hot air tunnel. The part of the machine guard used as the supply air duct 2 in the area of the hot part 11 has a partition wall 16 or 17 from other parts of the machine guard, whereby these other parts can be an inlet part 10 or a cooling part 12 of the hot air tunnel 1, which can be arranged adjacent to the hot part 11. By sealing the structure surrounding the outer surface 4 of the hot air tunnel 1 against the passage of air, it can be used for two purposes.In addition to the protective effect for the hot air tunnel 1, this also enables loss-free and safe air flow of the supply air. When supply air 5 is sucked in through the air filter 8, the filter differential pressure of the air filter 8 creates, as a side effect, a negative pressure zone surrounding the hot zone 11 in the area of the supply air duct 2, which further reduces the risk of particles or the like penetrating the hot zone 11 from the supply air duct 2. The features and components of the hot air tunnel 1 that have not been described separately but are provided with reference symbols correspond to the components with the same reference symbols in the . Fig. 1. Please refer to their description.

[0019] Fig. Figure 3 shows a schematic representation of a hot air tunnel 1, which is divided into three parts, namely an inlet part 10, a hot part 11, and a cooling part 12, which are arranged one behind the other in this order. The hot part 11 is provided with an air supply duct 2. A boundary surface of the air supply duct 2 is formed from an outer surface 4 of the boundary 13 of the interior 3 of the hot air tunnel 1. Further boundary surfaces of the air supply duct 2 are formed from two bulkheads 16 and 17, which separate the air supply duct 2 from the adjacent inlet part 10 and the adjacent cooling part 12. Towards the exterior of the hot air tunnel 1, a further boundary surface of the air supply duct 2 is formed by one or more surfaces 9, which is part of a cladding, a housing, a holding device, or the like of the hot air tunnel 1.The opening in the boundary 13 of the interior 3 of the hot air tunnel 1 and in one of the surfaces 9 of the supply air duct, each of which serves for the passage of supply air 5, are shown in the . Fig. 3 not shown.

[0020] The first, second, and third embodiments can be combined with each other; for example, a part 11, 12, or 13 of the third embodiment can have a cross-section of the first or second embodiment. The second embodiment can be a more detailed variant of the first embodiment. Further overlaps are conceivable and possible.

Claims

[1] Hot air tunnel (1) for heating objects in the interior (3) of the hot air tunnel (1) by means of hot air, wherein the hot air tunnel (1) has an outer surface (4) surrounding the interior of the hot air tunnel (1), and wherein the hot air tunnel (1) has on its outer surface (4) an air supply duct (2) through which air supply (5) can be supplied to the interior (3) of the hot air tunnel (1), so that air supply (5) in the air supply duct (2) can be preheated by heat which passes from the interior (3) of the hot air tunnel (1) through the outer surface (4) into the air supply duct (2), characterized by that the supply air duct (2) encloses the outer surface (4) of the hot air tunnel (1) in a ring-shaped or ring-like manner. [2] Hot air tunnel (1) according to claim 1, wherein a cladding surrounding the outer surface (4) of the hot air tunnel (1) and / or a housing protecting the hot air tunnel (1) and / or a holding device for the hot air tunnel (1) forms at least part of the supply air duct (2). [3] Hot air tunnel (1) according to claim 1 or 2, wherein the supply air duct (2) is sealed from the interior (3) of the hot air tunnel (1) and / or from the surroundings of the cladding and / or the holding device. [4] Hot air tunnel (1) according to one of the preceding claims, wherein the hot air tunnel (1) has a fan with which supply air (5) can be conveyed through the supply air duct (2) into the interior (3) of the hot air tunnel (1) and an air filter (8) is arranged in the supply air duct (2), wherein in particular the fan is arranged downstream with respect to the air filter (8) and / or the air filter (8) is arranged at or near an end of the supply air duct (2) which is upstream with respect to the supply air (5). [5] Hot air tunnel (1) according to one of the preceding claims, wherein the hot air tunnel (1) has a hot part (11) and one or more other parts (10, 12), each with its own supply air (5), wherein the temperature in the hot part (11) is higher than in the other parts (10, 12) and the supply air duct (2) carries supply air (5) for the hot part (11). [6] Hot air tunnel (1) according to one of the preceding claims, wherein the supply air duct (2) substantially completely encloses the outer surface (4) of at least a part of the hot air tunnel (1), and in particular in the case of claim 5 exclusively in the region of the hot part (11). [7] Hot air tunnel (1) according to one of the preceding claims, wherein the interior (3) of the hot air tunnel (1), in the case of claim 5 at least in the region of the hot part (11), is thermally insulated with respect to heat transfer to the outer surface (4) of the hot air tunnel (1). [8] Filling and / or packaging machine with a hot air tunnel (1) according to one of the preceding claims. [9] Method for heating supply air (5) for the interior (3) of a hot air tunnel (1), using a hot air tunnel (1) according to one of claims 1 to 7 or using a filling and / or packaging machine according to claim 8, wherein the supply air (5) in the supply air duct (2) surrounding the outer surface (4) of the hot air tunnel (1) in an annular or ring-like manner is heated by heat from the interior (3) of the hot air tunnel (1) which passes through the outer surface (4) at the supply air duct (2). [10] Method according to claim 9, wherein a negative pressure is generated in the supply air duct (2) compared to the environment of the supply air duct (2) by means of an air filter (8) and a fan which conveys supply air (5) from the supply air duct (5) against the pneumatic resistance of the air filter.

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