Bell-type furnace

Abstract

The invention relates to a bell-type furnace (1) comprising a mounting (3) and a process hood (2) which can be arranged on the mounting (3) in order to form a process chamber (6) for at least one object to be processed and which is arranged so as to directly adjoin the process chamber (6). The bell-type furnace also comprises a heating device (13) for controlling the temperature of the at least one object. The invention is characterized in that the process hood (2) has an inner sleeve (9), the outer surface of which is at least partly surrounded by a thermal insulation (10), or the thermal insulation (10) is arranged so as to directly adjoin the process chamber (6).

Description

[0001] HOODED VENTS

[0002] The invention relates to a hood furnace comprising a base and a process hood, which can be arranged on the base to form a process chamber for at least one object to be processed and which is arranged directly adjacent to the process chamber, as well as with a heating device for tempering the at least one object.

[0003] Furthermore, the invention relates to a base for a hood furnace comprising a circulation device for a process chamber atmosphere of the hood furnace, at least one guide element, and at least one connection area for a hood of the hood furnace.

[0004] The invention also relates to a thermal processing plant comprising at least two hood furnaces, each with a base.

[0005] Furthermore, the invention relates to a method for tempering at least one object in a hood furnace having a process hood and a base defining a process chamber, comprising the steps of: placing the at least one object on the base, arranging the process hood on the base, tempering the at least one object.

[0006] Hood furnaces are known from the prior art. For example, EP 2 738 502 A1 describes a hood annealing furnace for the thermal treatment of cold-rolled steel strip, comprising a base with a protective hood that can be placed thereon, beneath which a protective gas heated by a gas burner is circulated by a fan in order to heat the steel strip, which is wound in particular into a coil, under the protective hood in a protective gas atmosphere to a temperature of at least 500°C. This hood furnace is provided with an electric heating device powered by the public power grid with a heating output substantially corresponding to the heating output of the gas burner, with which the protective gas can be heated independently to a temperature above the recrystallization annealing temperature when the gas burner is switched off.The gas burners and the electric heating device are located outside and at a distance from the protective hood in / on a so-called heating hood.

[0007] Today, hood furnaces are generally operated in such a way that the hoods are exchanged between individual process steps. The protective hood is always present. For example, a heating hood, a cooling hood, etc., are exchanged, each of which is placed over the protective hood at a certain distance. This distance creates a heating chamber into which, for example, burners burn or in which electric heating elements are arranged. The generated thermal energy is then transferred via the protective hood material to the protective gas used to heat the objects to be tempered.

[0008] The object of the present invention is to provide a more environmentally friendly design of a hood furnace or a thermal processing plant equipped therewith as well as a more environmentally friendly method for tempering an object.

[0009] The object of the invention is achieved in the hood furnace mentioned at the outset in that the process hood has an inner shell which is surrounded at least in sections by thermal insulation on an outer surface or in that the thermal insulation is arranged directly adjacent to the process chamber.

[0010] Furthermore, the object of the invention is achieved with the base mentioned at the outset, in which the electrical heating device is arranged in the region of the at least one guide element.

[0011] In addition, the object of the invention is achieved with the above-mentioned thermal processing plant, in which the hood furnaces and / or the bases are designed according to the invention.

[0012] The object of the invention is also achieved with the method mentioned at the outset, according to which the process hood is used as the only hood during the entire tempering process.

[0013] The advantage here is that the (direct) arrangement of the thermal insulation on the process hood immediately adjacent to the process chamber reduces heat loss through this process hood. The base supports this, as it allows thermal energy to be introduced directly into the process chamber atmosphere. As a result, the hood furnace itself can be designed smaller, since no additional hood, such as a heating hood, etc., is required besides the innermost hood (in the case of the invention, the process hood, in the prior art, the protective hood). The radiation surface of a hood furnace can therefore be reduced. In addition to this reduction, a reduction in the space required by the hood furnace can also be achieved.By using a single process hood throughout the entire process for tempering an object, the energy required can also be reduced by reducing the number of crane movements required for handling hoods, as is necessary with the state of the art mentioned above. This, in turn, also allows for a reduction in operating effort and, as a result, the realization of a fully automatic hood furnace. Unmanned operation is possible from start to finish of the thermal treatment of an object, if necessary. By eliminating the need to move the hood during the thermal treatment, a corresponding time saving can also be achieved. By directly heating the process gas atmosphere, orBy using the protective gas in the process chamber, an overheating temperature, such as that encountered in the aforementioned prior art hood furnace due to indirect heating via the protective hood, can be avoided. This, in turn, contributes to an increase in the service life of the hood furnace and its components. Furthermore, direct heating and the avoidance of an overheating temperature can reduce heat losses, as the lower process temperature is not the overheating temperature of the heater that is relevant for thermal insulation.

[0014] According to one embodiment of the invention, the process hood can form an outer boundary of the hood furnace. This allows for a further reduction in the size of the hood furnace compared to prior art hood furnaces with the same process chamber volume.

[0015] To better protect the thermal insulation, one embodiment of the invention provides for the process hood to have a protective cover on an outer surface of the thermal insulation. In this embodiment, the thermal insulation is thus housed between two covers, namely the inner cover, which directly adjoins the process chamber, and the outer cover. The inner cover and / or the outer cover can be directly adjacent to the thermal insulation and, if necessary, even connected to it.

[0016] To increase mechanical stability and thus potentially reduce wall thickness, particularly of the inner shell and / or outer shell, a further embodiment of the invention may provide for the process hood to have beads. According to a further embodiment, to improve the mechanical connection of the thermal insulation to the inner shell and / or outer shell, the beads may be undercut.

[0017] According to another embodiment of the invention, the process hood can be provided with a shell section and is designed to be free of internal components, at least in the area of ​​the shell section. Particularly in conjunction with the base and the heating of the process gas atmosphere, this allows for a version of the hood furnace that is free of protruding pipes, fans, or general attachments on the outside of the process hood, thus allowing the hood furnace to have a longer service life due to less damage to system components.

[0018] In the preferred design, the bell furnace features an electric heating device located in the base. This eliminates the need for media lines, thus reducing maintenance requirements. In general, the elimination of gas heating reduces maintenance requirements for the bell furnace. Furthermore, climate-damaging CO2 and NOx emissions are eliminated. Compared to conventional electrically heated heating bells, energy savings of up to 5% to 10% have been achieved.

[0019] According to a further embodiment of the invention, a circulation device for the process chamber atmosphere with at least one guide element can be arranged in the base, and the electric heating device can be arranged in the region of the at least one guide element. The electric heating device can thus also contribute to the conduction of the process chamber atmosphere. Furthermore, the heat input into the process chamber atmosphere can be improved.

[0020] According to one embodiment of the invention, at least one cooling device can be arranged in the base. This eliminates the need for cooling fans in the area of ​​the process hood. Furthermore, it is easier to maintain the process hood throughout the entire temperature control program, since after the treatment of at least one object at elevated temperature, its controlled cooling is also easier to achieve without replacing the hood.

[0021] Furthermore, according to one embodiment of the invention, it can be provided that at least one heat exchanger is arranged in the base. This allows process heat to be used for another process, possibly for a process that takes place in a bell-type furnace operated in parallel. For this purpose, according to one embodiment of the thermal processing system, it can also be provided that at least one heat exchanger is arranged between at least two bases and / or between two process hoods, which has a flow connection to both bases and / or both process hoods. With this embodiment, an energy exchange between batches (stacks) or a heat extraction for an external process can be achieved.

[0022] According to a further embodiment of the invention, a gas guide element that can be displaced in the axial direction can be arranged in or on the base. This enables improved process atmosphere control. In particular, it is easier to switch between heating and cooling the at least one object, and the amount of thermal energy introduced into or removed from the process gas atmosphere can also be adjusted more easily.

[0023] According to another embodiment of the invention, the inner shell can be arranged at least partially at a distance from the thermal insulation. This makes it possible to form a gas guide channel within the process hood, through which a gas can be guided to heat the process chamber.

[0024] According to one embodiment, a gas guide cylinder can be arranged at least partially between the inner shell and the thermal insulation. This allows for a better distribution of heat energy or cooling medium in the gas guide channel. Since heating by radiant energy plays only a minor role compared to conventional bell furnaces, heat transfer takes place, at least for the most part, solely by convection. The provision of a gas guide cylinder leads to a significant improvement in this regard.

[0025] To further improve this effect, according to an embodiment of the invention, it can be provided that the gas guide cylinder extends over at least 70% of the height of the process chamber.

[0026] Surprisingly, to improve heat transfer from the gas in the gas guide channel to the circulating gas in the process chamber, it is sufficient if, according to a further embodiment of the invention, the gas guide cylinder is arranged at a distance from the inner shell or the thermal insulation that is selected from a range between 5 mm and 30 mm. This, in turn, enables a continued compact design of the process hood with a slight reduction in the size of the process chamber, or a slight increase in the size of the process hood while maintaining the same size.

[0027] In order to improve the inflow conditions into the gas guide channel formed with the gas guide cylinder, according to an embodiment variant of the invention, it can be provided that an inflow opening for the gas in the channel formed between the gas guide cylinder and the inner shell or the thermal insulation is formed with a bevel and / or rounding.

[0028] According to another embodiment of the invention, it can be provided that it has at least one temperature measuring element which is arranged at a height which corresponds to between 50% and 100% of the height of the process chamber. The arrangement of a temperature measuring element per se is known, but by arranging it at the specified height, “overheating” of the temperature measuring element, i.e. an excessively high temperature in the region of the temperature measuring element, can be avoided. This allows the temperature in the hood furnace to be regulated more quickly, which can improve the control process itself. This is particularly advantageous in the hood furnace according to the invention with the temperature control of the at least one component which takes place predominantly by convection.

[0029] To further improve this effect, according to an embodiment of the invention, the temperature measuring element can be arranged in the region of the end of the gas guide cylinder.

[0030] According to one design variant of the base, the hood can be designed as a process hood with thermal insulation arranged on an outer surface or as a gas-heated heating hood. Even when using a gas-heated heating hood, the base can achieve a reduction in environmental impact by heating only with gas during the high-heating phase of the hood furnace and with electricity during the subsequent control phase. This hybrid operation allows a reduction in NOx emissions even when using a gas-heated heating hood.

[0031] For the above reasons, according to embodiment variants of the method, it can be provided that a protective gas is circulated in the process chamber and that the protective gas is heated directly with at least one electrical heating device, and / or that for cooling the at least one object, at least a partial flow of the protective gas is passed through at least one heat exchanger, wherein the heat exchanger is optionally arranged in the base of the hood furnace.

[0032] For a better understanding of the invention, it is explained in more detail using the following figures.

[0033] They show in a simplified, schematic representation:

[0034] Fig. 1 shows a section through a hood furnace;

[0035] Fig. 2 shows a section of the hood furnace according to Fig. 1;

[0036] Fig. 3 shows a section of a variant of a process hood in side view;

[0037] Fig. 4 shows a base of a hood furnace in an oblique view and partly in section;

[0038] Fig. 5 shows a section of the hood furnace;

[0039] Fig. 6 shows a section of a base of the hood furnace;

[0040] Fig. 7 shows a variant of a thermal processing plant;

[0041] Fig. 8 shows a variant of a hood furnace.

[0042] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the position information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these position information must be applied analogously to the new position in the event of a change in position.

[0043] Fig. 1 shows a cross-sectional view of a design variant of a hood furnace 1. A hood furnace belongs to the category of industrial furnaces. It is defined by a movable hood that is placed on a base. Items to be processed are placed on the base in advance. A hood furnace is therefore an industrial furnace that operates periodically (in batches), i.e., not continuously. The hood can, for example, be round or polygonal. Accordingly, the hood can be, for example, a cylinder closed at the top or a cuboid, etc. Since this is known from the prior art, reference is made to the relevant prior art for further details.

[0044] The hood furnace 1 thus has a hood, in the present invention a process hood 2, and a base 3. The process hood 2 stands on the base 3 during the process. In particular, an end face 4 of the process hood 2 lies completely sealingly against a surface 5 of the base 3, optionally with an intermediate seal.

[0045] The hood furnace 1 has the process hood 2. The term "process hood" is intended to express that, unlike prior art hood furnaces, the hood of the hood furnace 1 remains or can remain on the base 3 throughout the entire tempering of at least one object, and no further hood is arranged above this process hood 2 for individual treatment steps, such as heating the object with a heating hood or cooling the object with a cooling hood. The process hood 2 is therefore preferably the only hood used on the hood furnace 1. "Preferred" means that a hybrid operation is also possible with the base 3, as will be described in more detail below. A different hood than the one described below is used as the process hood 2.

[0046] The term “temperature control” includes in particular heating to a higher temperature, maintaining the temperature for a predefined period of time and cooling to a lower temperature, usually a temperature greater than or equal to 20 °C.

[0047] An object (particularly a metallic object) that is processed using the hood furnace 1 can be a product, such as a sheet or a blank, an ingot, etc., or a raw material, such as a metal, etc. The process can be, for example, the melting of the object or a specific reaction in, on, or with the object, such as a phase transformation, hardening of a metallic object, tempering of an object, recrystallization, etc. The object can be treated individually or several objects can be treated simultaneously in the hood furnace 1. If there are several objects, these are preferably grouped into batch stacks. So-called coils can also be treated. These lists are only examples and are not intended to be limiting.

[0048] The hood furnace 1 can be used, for example, for objects made of aluminum or an aluminum alloy or generally non-ferrous metals or steel.

[0049] The process hood 2, together with the base 3, defines a process chamber 6 for receiving the at least one object. In particular, the process hood 2 forms a shell section 7 and a lid section 8 of the process chamber 6.

[0050] Holding devices for the simultaneous treatment of several objects in the hood furnace 1 can be designed according to the state of the art.

[0051] The process hood 2 has an inner shell 9 extending over the entire inside (i.e., the inner surface) of the process hood 2, on which inner shell a thermal insulation 10 is arranged and optionally connected. The thermal insulation 10 preferably extends over the entire outer surface of the inner shell 9. Preferably, the process hood 2 also has a protective shell 11 (also referred to as an outer shell), so that the thermal insulation 10 is arranged between the inner shell 9 and the protective shell 11. The inner shell 9 and / or the protective shell 11 can also be arranged in the region of the end face 4, so that an intermediate space between the inner shell 9 and the protective shell 11 is completely closed.

[0052] The inner shell 9 is arranged directly adjacent to the process chamber 6. It is preferably made of a metal, such as steel in particular. Optionally, the inner shell 9 can be made at least partially of a ceramic material or glass. The inner shell 9 can have a wall thickness selected from a range of 2 mm to 15 mm.

[0053] According to one embodiment, the process hood 2 can also be designed without the inner shell 9, so that the thermal insulation 10 is arranged directly adjacent to the process chamber 6, although this is not the preferred embodiment.

[0054] In this embodiment, the thermal insulation 10 (also referred to as thermal insulation) is arranged directly adjacent to the inner shell 9. Preferably, the thermal insulation 10 extends over the entire volume of this intermediate space between the inner shell 9 and the protective shell 11 (with the exception of any internal fittings or attachments) or over the entire outer surface of the inner shell 9 (with the exception of any internal fittings or attachments).

[0055] If necessary, the thermal insulation 10 can also be pre-loaded with a pressure that can be applied between the inner shell 9 and the protective shell 11 to better withstand mechanical stresses resulting from temperature changes. For example, the thermal insulation 10 can be pressurized with nitrogen or argon.

[0056] The thermal insulation 10 comprises or consists of a commercially available insulating material, such as ceramic fiber materials, mineral wool, graphite, etc.

[0057] The thermal insulation 10 can also be multi-layered, for example, comprising a first insulating layer and a second insulating layer, particularly one directly adjacent to it. The thermal insulation 10 can also have more than two insulating layers. It can be provided that the multiple insulating layers consist of or comprise different materials.

[0058] The thermal insulation 10 can have a wall thickness selected from a range of 50 mm to 500 mm

[0059] The protective sheath 11 is arranged directly adjacent to the thermal insulation 10. It is preferably made of a metal, such as steel. The protective sheath 11 can have a wall thickness selected from a range of 4 mm to 15 mm.

[0060] The thermal insulation 10 is preferably connected to the inner shell 9. Alternatively or additionally, the protective sheath 11 can be connected to the inner shell 9. In this case, the thermal insulation 10 can also be arranged loosely in the space between the inner shell 9 and the protective sheath 11.

[0061] The thermal insulation 10 can be connected to the inner shell 9 and / or the protective shell 11 in a materially bonded manner (for example by means of a high-temperature adhesive) and / or in a form-fitting manner and / or in a force-fitting manner (for example by means of screws or generally retaining bolts). The inner shell 9 can be provided with beads 12. To clarify this embodiment, a bead 12 is shown in an oversized manner in Fig. 1. If necessary, the form-fitting connection to the thermal insulation 10 can also be established via these beads 12. In addition to a rectangular, square or polygonal cross-section of the beads 12, they can also be designed with an undercut, as is shown using the example of a dovetail shape in Fig. 1. The undercut of the beads 12 can, however, also have a different shape.

[0062] Preferably, a plurality of beads 12 are arranged over the surface of the inner shell 9, which beads can also be annular in the casing section 7. The beads 12 can have a depth selected from a range of 2 mm to 25 mm.

[0063] The protective cover 11 can also be provided with beads. The details of the beads

[0064] 12 of the inner shell 9 can be transferred to the beads of the protective shell 11.

[0065] As already explained, the process hood 2 is the only hood arranged on the hood furnace 1 during a process. Therefore, according to a preferred embodiment of the hood furnace 1, the process hood 2 also forms the outer boundary of the hood furnace 1 in the region of the shell section 7 and / or the cover section 8. Furthermore, according to a preferred embodiment, the shell section 7 and preferably also the cover section 8 of the process hood 2 can be designed without any internal components.

[0066] The hood furnace 1 also has a heating device 13, which can be seen in Fig. 2, which shows a section of the hood furnace 1 in the area of ​​the base 3. The heating device

[0067] 13 is arranged in the base 3 (can therefore also be referred to as a base heater). In the embodiment of the hood furnace 1 according to Fig. 1, the heating device 13 in the base 3 is the only heating device 13 of the hood furnace 1. However, the hood furnace 1 can also have a further heating device 14. This can be arranged in the process hood 2, which, according to one embodiment, can be a gas-fired or electrically heated process hood 2, i.e. can have at least one gas burner 15 or at least one electric heating element. In this case, the process hood 2 can be designed as a so-called heating hood, which has the inner shell 9 and the protective shell 11, whereby, however, the space between the inner shell 9 and the protective shell 11 is available for gas firing or electric heating.However, in this embodiment, the base 3 also has the heating device 13, so that hybrid heating is possible, in which the gas-fired heating device 14 or the further electric heater is used only for the heating process, and subsequently the remainder of the required thermal energy (e.g. for maintaining the temperature) is generated via the heating device 13 of the base 3.

[0068] The base 3 with the heating device 13 can therefore form an independent part of the invention for a hood furnace 1.

[0069] To create a flow of the process chamber fluid, in particular the protective gas (also referred to as circulating gas) in the process chamber 6 and to redistribute the thermal energy, a fan 16 or a turbine can be provided in the base 3, with which the gaseous medium is circulated in the process chamber 6. The heating device 13 can be arranged in the flow channel 17 formed centrally and above the fan 16, which is more clearly visible in Fig. 5. The left-hand part of Fig. 5 shows the circulation of the warm process chamber fluid with flow arrows 18. Accordingly, the process chamber fluid is sucked in by the fan 16, flows past the heating device 13 and / or through the heating device 13 to absorb the thermal energy, and then flows upward along the inner shell 9.

[0070] For the sake of completeness, it should be noted that during operation of the bell furnace 1, the process chamber 6 is closed off, so that the at least one object in the process chamber 6 is only directly flushed or heated by the circulating gas. This can also be referred to as "batch heating."

[0071] The fan 16 can be driven by a fan motor 19, which is preferably arranged below a fan wheel 20.

[0072] The heating device 13 of the base 3 is preferably an electrical heating device, ie in particular a heating device 13 with resistance heating elements 21.

[0073] According to one embodiment variant of the invention, it can be provided that at least one guide device 22 with a guide element 23 is arranged in the base 3 for the circulation device for the gaseous process chamber fluid, and that the electric heating device 13 is arranged in the region of the at least one guide element 23, as can be seen from Fig. 2 and in particular Fig. 6. Preferably, several guide elements 23 are arranged distributed over the circumference of the base 3. The at least one guide element 23 can, for example, be curved in the shape of a blade. If there are several guide elements 23, flow channels 24 are formed between them.

[0074] Plate elements can now be arranged vertically or horizontally between the guide elements 23 or between at least some of the guide elements 23 as resistance heating elements 21. The plate elements can also be designed with a curved blade shape. In particular, they can at least approximately replicate the curvature of the guide elements 23, whereby the plate elements can also contribute to flow guidance and not just to heating the gaseous medium.

[0075] It is also possible to stack several panel elements vertically on top of each other or arrange them side by side and electrically insulate them from each other with insulating elements. The stack can be held together with fastening elements.

[0076] Preferably, such plate elements or generally resistance heating elements 21 can be arranged distributed over the entire circumference of the base 3.

[0077] According to another embodiment, alternatively or in addition to the above-described embodiments of the heating device 13 in the base 3, the fan wheel 20 with the fan motor 19 can be used for temperature control. The temperature in the process chamber 6 can be changed by changing the power consumption of the fan wheel 20 with the fan motor 19. If necessary, another gas different from the process chamber fluid can be mixed into the gaseous process chamber fluid, and the power consumption can be changed by changing the mixing ratio of the gases. A gas whose weight is at least 50% greater than the weight of the process chamber fluid can be used as the additional gas.Alternatively or in addition to changing the power consumption of the fan wheel 20 with the fan motor 19, the pressure in the process chamber 6 and / or the speed of the fan motor 19 and / or the fan wheel 20 can be changed.

[0078] According to a further embodiment of the bell furnace 1 or the base 3, it is possible for at least one cooling device 25 to be arranged in the base 3. The cooling device 25 can, for example, be an electrically operated fan wheel that blows cooling air or, generally, a cooling gas through a channel in the base 3. According to a further embodiment, a heat exchanger 26 can also be arranged in the base 3. In this case, the cooling device 25 is preferably designed as a heat exchanger 26. For example, the heat exchanger 26 or the cooling device 25 can be designed as a tube bundle heat exchanger, which can have coolant tubes running around its entire circumference, as can be seen from Fig. 4. Instead of the entire circumference, several (tube bundle) heat exchangers 26 can also be arranged one behind the other in a circumferential direction 27 to vary the cooling capacity.

[0079] It should be noted that, for reasons of clarity, connections for supplying or discharging a cooling fluid to and from the heat exchanger 26 are not shown.

[0080] The at least one heat exchanger 26 can also be designed differently. However, it is preferably arranged in the base 3.

[0081] Due to the arrangement in the base 3, the temperature control of at least one object in the hood furnace 1 can also include its controlled cooling, whereby the process hood 2 can be designed simply and, in particular, also has no cooling lines, etc. The media supply of the heat exchanger 26 or generally the supply of the hood furnace 1 with electrical energy, various media, etc., can be carried out exclusively via the base 3, which is usually stationary.

[0082] To improve control of the cooling of the object in the process chamber 6, a gas guide element 29 that can be moved in an axial direction 28 can be arranged in or on the base 3, as is best seen in Figs. 4 and 5. The gas guide element 29 can be cylindrical or generally sleeve-shaped (or, in the case of non-cylindrical bell furnaces, have a shape that follows the base shape, for example, cuboid-shaped), with an upper section being designed in the shape of a guide element, for example having a guide surface 30 that runs diagonally upwards. The guide surface 30 deflects the process chamber atmosphere sucked in by the fan wheel or fan 16, as can be seen in Fig. 5. In the closed position of the gas guide element 29 (left part of Fig. 5), the entire volume flow of the sucked-in process chamber atmosphere is deflected upwards again.Since the gas guide element 29 is designed to be adjustable, a flow channel 31 can be formed between the gas guide element 29 and a base body 32, against which the gas guide element 29 rests in the closed position (top), by adjusting it from the closed position to an open position, so that the entire volume flow of the sucked-in process chamber atmosphere or a partial flow thereof is redirected in the direction of the heat exchanger 26. The residual flow of the sucked-in process chamber atmosphere is redirected upwards via the guide surface. The partial volume flow flowing out into the flow channel 31 flows through the heat exchanger 26 or past it, whereby the partial volume flow cools down. This partial volume flow is then reunited with the residual volume flow by being discharged upwards from the heat exchanger 26.If the entire volume flow is passed over / through at least one heat exchanger 26, this reunification is naturally omitted.

[0083] The height adjustment of the gas guide element 29 can be carried out in steps or continuously, so that the cross-sectional area of ​​the flow channel 31 and thus the size of the partial volume flow of the process chamber atmosphere through this flow channel 31 can be changed accordingly.

[0084] For the sake of completeness, it should be noted that the process hood 2 can be connected to the base 3 in accordance with the state of the art, for example by means of a hydraulic press.

[0085] Fig. 7 shows a variant embodiment of a thermal processing system 33. This comprises at least two hood furnaces 1 according to the invention, each with a base 3, which is preferably also formed according to the invention. In the illustrated variant embodiment of the thermal processing system 33, as an alternative or in addition to the heat exchanger 26 in the respective base 3, at least one heat exchanger 34 is arranged between the two bases 3 and / or between two process hoods 2. The heat exchanger 34 has flow connections to both bases 3 and / or to both process hoods 2. It should be noted that the representation in Fig. 7 is only schematic in nature.

[0086] With this design variant, it is possible to transfer thermal energy from one hood furnace 1 to another hood furnace 1, so that, for example, the thermal energy obtained during the cooling of one hood furnace 1 can be used to heat the other hood furnace 1.

[0087] According to one embodiment variant, it can be provided that at least two hood furnaces 1 in a thermal processing plant 33 are thermally coupled directly to one another, i.e. without the heat exchanger 34 between the two bases 3 of Fig. 7. In this case, the process gas, i.e. for example the protective gas, in a first hood furnace 1 can be used via at least one fluid line to (pre-)heat a further hood furnace 1, i.e. the process gas, in particular the protective gas, and subsequently the at least one object in the further hood furnace 1. The waste heat of the first hood furnace 1, which is present as a result of the cooling of the first hood furnace 1, can therefore be used to directly heat the further hood furnace 1. In this case, the process gas containing the waste heat can be fed to the further base 3 of the further hood furnace 1 in order to communicate with its fan 16 orTurbine to be redistributed (and optionally sucked in), and / or the process gas from the further hood furnace 1 can be fed to the base 3 of the first hood furnace 1 in order to be redistributed (and optionally sucked in) by its fan 16 or turbine. In both hood furnaces 1, the hoods are designed as process hoods 2, so that they do not have to be exchanged during this heat extraction from the first hood furnace 1 and the heat coupling into the further hood furnace 1. The corresponding piping for transporting the process gases between the hood furnaces 1 can be arranged exclusively between the two bases 3 of the two hood furnaces 1, for example in the floor, so that no fluid lines for this purpose lead into or from the process hoods 2.

[0088] This thermal energy utilization system can also be extended to more than two bell furnaces 1. In this case, appropriate piping (e.g., in the floor) can be provided, from which branch line(s) lead to the individual bell furnaces 1, which serve to remove or supply (warm or heated or cold) process gas. For example, one or at least two ring line(s) can be provided, to which the bell furnaces 1 are connected for gas supply or gas exchange.

[0089] The heat extraction or heat supply can take place directly between the hood furnaces 1. However, heat exchange preferably takes place via the at least one heat exchanger 26 in the respective base 3 of the respective hood furnace 1. The process gas can therefore be supplied either to the heat exchanger 26 in the base 3 of the hood furnace 1 containing the process gas and / or to the heat exchanger 26 in the base 3 of the further hood furnace 1 into which the thermal energy is to be fed. Fig. 8 shows a further embodiment of the hood furnace 1 in section. In the following, only differences from that described above and details of further embodiments of the hood furnace 1 are explained in more detail. The above explanations regarding the remaining details of the hood furnace 1 can also be applied to the hood furnace 1 in Fig.8, so that reference is made to the above explanations, which can be transferred accordingly to the embodiment variant of the hood furnace 1 according to Fig. 8. This also applies to the explanations regarding the method according to the invention and to the base 3 and the thermal processing system 33.

[0090] Unlike the embodiment of the process hood 2 according to Fig. 1, the process hood 2 according to Fig. 8 additionally has a gas guide cylinder 35 between its inner shell 9 and the thermal insulation 10. The gas guide cylinder 35 is arranged at a distance from the inner shell 9 and / or at a distance from the thermal insulation 10. As a result, a gas guide channel 36 is formed between the inner shell 9 and the gas guide cylinder 35 and / or between the thermal insulation 10 and the gas guide cylinder. The gas guide channel 36 is preferably formed between the inner shell 9 and the gas guide cylinder 35, since this allows thermal energy from the gas guided in the gas guide channel 36 to be transferred directly to the inner shell 9.

[0091] Generally, within the scope of the invention, i.e., also in the embodiment of the hood furnace 1 or the process hood 2 according to Fig. 1, it is possible for the inner shell 9 to be arranged at least partially at a distance from the thermal insulation 10, so that the gas guide channel 36 between the inner shell 9 and the thermal insulation 10 can also be formed without a gas guide cylinder 35. In this case, the inner shell 9 can form not only the boundary to the process chamber 6 but also the gas guide cylinder 35.

[0092] The gas guide cylinder 35 preferably extends continuously in the circumferential direction of the inner shell 9, i.e. completely.

[0093] Furthermore, according to a preferred embodiment, the gas guide cylinder 35 extends over at least 70%, in particular at least 80%, of a height 37 of the process chamber 6. The gas guide cylinder 35 can also extend over the entire height of the hood shell, i.e. the shell section 7 (i.e. without the hood cover or the cover section 8) of the process hood 2. The height 37 of the process chamber 6 is measured starting at a support plane 38 of the hood furnace 1 for the at least one object to be treated in the process chamber 6 or the holding device for the object to be treated and extends in the axial direction 28 up to the highest point on the underside / inside of the inner shell 9. The gas guide cylinder 35 can also extend in the axial direction 28 beyond the inner shell 9 up to the underside of the thermal insulation 10 of the hood cover (cover section 8).

[0094] However, the gas guide cylinder 35 may also have a smaller height (less than 70% of the height 37 of the process chamber 6), although this is not preferred.

[0095] The gas guide cylinder 35 can also extend over 100% of the height 37 of the process chamber 6.

[0096] The gas guide cylinder 35 is preferably made of a metal, such as steel. Optionally, the gas guide cylinder 35 may be made at least partially of a ceramic material or glass.

[0097] Since the gas guide cylinder 35 has no load-bearing function, it can have a wall thickness selected from a range of 2 mm to 15 mm.

[0098] The gas guide cylinder 35 can be connected to the inner shell 9 and / or the thermal insulation 10 and / or the protective cover 11. The connection can be materially bonded and / or positively connected and / or non-positively connected (e.g., by means of screws or generally retaining bolts). For example, the gas guide cylinder 35 can be arranged directly adjacent to the thermal insulation 10.

[0099] However, it is also possible for the gas guide cylinder 35 to be arranged in a self-supporting manner (ie without any further connection to one of the components of the process hood 2), although this is not the preferred embodiment.

[0100] The gas guide cylinder 35 can be arranged at a distance 39 from the inner shell 9 that is suitable for the gas line. For example, this distance 39 can be up to 100 mm. According to a preferred embodiment of the hood furnace 1 or the process hood 2, however, the distance 39 of the gas guide cylinder 35 from the inner shell 9 can be selected from a range between 5 mm and 30 mm, in particular between 5 mm and 15 mm. The distance 39 corresponds to the clear width of the gas guide channel 36.

[0101] It is also possible to vary the distance 39 between the gas guide cylinder and the inner shell 9 across the height of the gas guide cylinder 35 to change the flow conditions in the gas guide channel 36. For example, this can be achieved by a truncated cone-shaped design of the gas guide cylinder 35 or by appropriate fittings in the gas guide channel 36.

[0102] As can be seen from the flow arrows 18 in Fig. 5, the gas, i.e. the process gas, is circulated in the process chamber 6 and flows upwards along the inside of the inner shell 9. In the design variant of the hood furnace 1 or the process hood 2 with the gas guide cylinder 35, the additional gas that is guided in the gas guide cylinder, for example air, flows along the outside of the process hood 2. The process gas is thus separated from the additional gas by the inner shell 9 and is (additionally) heated by the additional gas via heat conduction through the inner shell 9. For this purpose, the additional gas can be fed to the gas guide channel 36 in the region of the base 3, for which purpose a transfer channel 40 can be formed or arranged in the process hood 2. The transfer channel 40 can, for example, be designed as an annular channel.In order to improve the inflow of the gas into the gas guide channel, according to one embodiment variant it can be provided that an inflow opening 41 for the gas in the gas guide channel 36 formed between the gas guide cylinder 35 and the inner shell 9 is formed with a bevel and / or rounding 42.

[0103] The additional gas can be removed from the gas guide channel 36 in an upper section of the process hood 2 and fed back to the transfer channel 40 via a line 43. This circuit can optionally be supported by a conveying device, such as a suction element or a blower, etc. It is also possible for the line 43 to be routed through at least one heat exchanger, through which thermal energy can be removed from or added to the additional gas. Direct heating of the additional gas is also possible.

[0104] Fig. 8 also shows the heat exchanger 34 in the base 3 of the bell furnace 1. However, it should be noted that its arrangement is only optional.

[0105] To regulate the temperature in the process chamber 6, at least one temperature measuring element 44 (e.g., a thermocouple) can be provided. The at least one temperature measuring element 43 can be arranged, for example, in the base 3, in particular in the region of the heating device 13 (see Fig. 6). According to another embodiment of the invention, however, it can be provided that the temperature measuring element 43 is arranged at a height that corresponds between 50% and 100% of the height 37 of the process chamber 6. For example, the temperature measuring element 43 can be arranged in the region of an end 45 of the gas guide cylinder 35.

[0106] In these embodiments of the arrangement of the at least one temperature measuring element 43, no further temperature measuring element for directly regulating the temperature in the process chamber 6 can be arranged in the base 3 or in the area of ​​the heating device 13. In particular, no further temperature measuring element is arranged in the area of ​​the resistance heating elements 21 (see Fig. 6), even if the electric heating device 13 is the only heating device of the hood furnace 1. However, at least one further temperature measuring element can be arranged in the base 3 if it is also used to cool the process chamber 6, as explained above. This further temperature measuring element then does not serve to regulate the heating device 13, as is the case with the described temperature measuring element 43.

[0107] With the hood furnace 1, a method for tempering at least one object according to the above statements is possible.

[0108] According to the above statements, the invention relates to a hood furnace 1 which uses the process hood 2 as the only hood during the entire tempering process.

[0109] The embodiments show possible design variants of the hood furnace 1, the base 3 and the thermal processing system 33, whereby it should be noted at this point that combinations of the individual design variants are also possible.

[0110] For the sake of clarity, it should be noted that, for a better understanding of the structure, the bell furnace 1, the base 3, and the thermal processing system 33 are not necessarily shown to scale.

[0111] Hood furnace 30 guide surface

[0112] Process hood 31 flow channel

[0113] Socket 32 ​​socket body

[0114] Front face 33 thermal processing plant

[0115] Surface 34 heat exchanger

[0116] Process chamber 35 gas guide cylinder

[0117] Shell section 36 gas duct

[0118] Cover section 37 height

[0119] Inner shell 38 support level

[0120] Thermal insulation 39 distance

[0121] Protective cover 40 transfer channel

[0122] Bead 41 inlet opening

[0123] Heating device 42 rounding

[0124] Heating device 43 Gas burner line 44 Temperature measuring element

[0125] Fan 45 end

[0126] flow channel

[0127] Flow arrow

[0128] Fan motor

[0129] Fan wheel

[0130] resistance heating element

[0131] Guidance device

[0132] Guide element

[0133] flow channel

[0134] Cooling device heat exchanger

[0135] Circumferential direction Axial direction Gas guide element

Claims

Patent claims 1. Hood furnace (1) comprising a base (3) and a process hood (2) which can be arranged on the base (3) to form a process chamber (6) for at least one object to be processed and which is arranged directly adjacent to the process chamber (6), and with a heating device (13) for controlling the temperature of the at least one object, characterized in that the process hood (2) has an inner shell (9) which is surrounded at least in sections on an outer surface by thermal insulation (10) or that the thermal insulation (10) is arranged directly adjacent to the process chamber (6).

2. Hood furnace (1) according to claim 1, characterized in that the process hood (2) forms an outer boundary of the hood furnace (1).

3. Hood furnace (1) according to claim 1 or 2, characterized in that the process hood (2) has a protective cover (11) on an outer surface of the thermal insulation (10).

4. Hood furnace (1) according to one of claims 1 to 3, characterized in that the process hood (2) has beads (12).

5. Hood furnace (1) according to claim 4, characterized in that the beads (12) are designed as undercuts.

6. Hood furnace (1) according to one of claims 1 to 5, characterized in that the process hood (2) has a shell section (7) and is designed free of internal components at least in the region of the shell section (7).

7. Hood furnace (1) according to one of claims 1 to 6, characterized in that an electric heating device (13) is arranged in the base (3).

8. Hood furnace (1) according to claim 7, characterized in that a circulation device for the process chamber atmosphere with at least one guide element (23) is arranged in the base (3), and that the electrical heating device (13) is arranged in the region of the at least one guide element (23).

9. Hood furnace (1) according to one of claims 1 to 8, characterized in that at least one cooling device (25) is arranged in the base (3).

10. Hood furnace (1) according to one of claims 1 to 9, characterized in that at least one heat exchanger (26) is arranged in the base (3).

11. Hood furnace (1) according to one of claims 1 to 10, characterized in that a gas guide element (29) which is displaceable in the axial direction (28) is arranged in or on the base (3).

12. Hood furnace (1) according to one of claims 1 to 11, characterized in that the inner shell (9) is arranged at least in sections at a distance from the thermal insulation (10).

13. Hood furnace according to claim 12, characterized in that a gas guide cylinder (35) is arranged at least in sections between the inner shell (9) and the thermal insulation (10).

14. Hood furnace (1) according to claim 13, characterized in that the gas guide cylinder (35) extends over at least 70% of a height (37) of the process chamber (6).

15. Hood furnace (1) according to claim 13 or 14, characterized in that the gas guide cylinder (35) is arranged at a distance (39) from the inner shell (9) or from the thermal insulation (10) which is selected from a range between 5 mm and 30 mm.

16. Hood furnace (1) according to one of claims 13 to 15, characterized in that an inflow opening (41) for the gas in the space between the gas guide cylinder (35) and the inner shell (9) or the thermal insulation (10) is formed with a bevel and / or rounding (42).

17. Hood furnace (1) according to one of claims 1 to 16, characterized in that it has at least one temperature measuring element (43) which is arranged at a height which corresponds to between 50% and 100% of the height (37) of the process chamber (6).

18. Hood furnace (1) according to claim 17, characterized in that the temperature measuring element (43) is arranged in the region of one end (44) of the gas guide cylinder (35).

19. Base (3) for a hood furnace (1) comprising a circulation device for a process chamber atmosphere of the hood furnace (1), at least one guide element (23), and at least one connection area for a hood of the hood furnace (1), characterized in that the heating device (13) is an electrical heating device (13) and is arranged in the area of ​​the at least one guide element (23).

20. Base (3) according to claim 12, characterized in that the hood is designed as a process hood (2) with thermal insulation arranged on an outer surface or as a gas-heated heating hood.

21. Thermal processing plant (33) comprising at least two hood furnaces (1), each with a base (3), characterized in that the hood furnaces (1) are formed according to one of claims 1 to 18 or the bases (3) are formed according to one of claims 19 or 20.

22. Thermal processing system (33) according to claim 21, characterized in that at least one heat exchanger (34) is arranged between at least two bases (3), which has a flow connection to both bases (3).

23. A method for tempering at least one object in a hood furnace (1) having a process hood (2) and a base (3) defining a process chamber (6), comprising the steps: Placing the at least one object on the base (3), Arrangement of the process hood (2) on the base (3), Tempering of the at least one object, characterized in that the process hood (2) is used as the only hood during the entire tempering process.

24. Method according to claim 23, characterized in that a protective gas is circulated in the process chamber (6) and that the protective gas is heated directly with at least one electrical heating device (13).

25. Method according to claim 23 or 24, characterized in that for cooling the at least one object, at least a partial flow of the protective gas is passed through at least one heat exchanger (26).

26. Method according to claim 25, characterized in that the heat exchanger (26) is arranged in the base (3) of the hood furnace (1).

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