Temperature-control system

Abstract

The invention relates to a system (1) for controlling the temperature of a plurality of industrial furnaces (2), the system comprising a fluid line (3) and a conveying apparatus (4) for conducting a temperature-control fluid to the industrial furnaces (2), and the system having connection devices (6) for fluidically connecting the industrial furnaces (2) to the fluid line (3), wherein the fluid line (3) is designed as a loop line.

Description

[0001] TEMPERATURE CONTROL SYSTEM

[0002] The invention relates to a system for temperature control of several industrial furnaces comprising a fluid line and a conveying device for conveying a temperature control fluid to the industrial furnaces, and with connection devices for the fluidic connection of the industrial furnaces to the fluid line.

[0003] The invention further relates to an industrial furnace arrangement comprising several industrial furnaces and a system for temperature control of the several industrial furnaces which is fluid-connected to the industrial furnaces.

[0004] Furthermore, the invention relates to a method for temperature control of several industrial furnaces with a system for temperature control of the several industrial furnaces, which has a fluid line and a conveying device with which a temperature control fluid is conveyed to the industrial furnaces, and with connection devices with which the industrial furnaces are fluidically connected to the fluid line.

[0005] Conserving resources and reducing climate-relevant gases also require a rethink in the field of industrial furnaces. The use of heat exchangers in such industrial furnaces to improve energy efficiency is already known. For example, WO 2013 / 087646 Al describes a furnace for heat-treating materials to be annealed, wherein the furnace has a closable first furnace chamber, which is designed for receiving and heat-treating materials to be annealed by means of thermal interaction between the materials being annealed and a first annealing gas that can be heated or cooled in the first furnace chamber, and a removable first protective hood by means of which the first furnace chamber can be closed. Furthermore, a first heat exchanger, located at least partially inside the first furnace chamber closed by the first protective hood, is provided for exchanging heat with the first annealing gas within the first protective hood.The heat exchanger is arranged relative to a first glow gas fan for driving the glow gas in such a way that in every operating state of the furnace, the glow gas driven by the first glow gas fan flows into the heat exchanger.

[0006] The industrial furnace system formed by the furnace can include a second furnace. This allows the material to be heat-treated in the second furnace chamber with a second annealing gas, whereby the second annealing gas is heated by transferring heat through a second heat exchanger located at least partially inside the sealed second furnace chamber within the second protective hood, which, together with the first heat exchanger, is supplied with heat from a common heating unit.

[0007] It is possible for a transport fluid path to have a plurality of valves that can be switched in such a way that a furnace can be operated selectively in one of the following operating modes: a first operating mode in which the transport fluid actuator thermally couples the transport fluid with the second annealing gas, so that the transport fluid extracts heat from the second annealing gas and supplies it to the first annealing gas in order to heat the first furnace chamber and cool the second furnace chamber; a subsequent second operating mode in which a heating unit, in particular internal or external, further heats the first furnace chamber, and in which, in a separate path, the transport fluid actuator supplies the transport fluid to the connected cooler for cooling and thermally couples the cooled transport fluid with the second annealing gas in order to further cool the second furnace chamber;a subsequent third operating mode in which the transport fluid drive thermally couples the transport fluid with the first annealing gas, so that the transport fluid extracts heat from the first annealing gas and transfers it to the second annealing gas to heat the second furnace chamber and cool the first furnace chamber; a subsequent fourth operating mode in which the heating unit continues to heat the second furnace chamber, and in which, in a separate path, the transport fluid drive supplies the transport fluid to the connected cooler for cooling and thermally couples the cooled transport fluid with the first annealing gas to further cool the first furnace chamber.

[0008] It is an object of the present invention to provide an improved possibility for reducing energy consumption in an industrial furnace arrangement.

[0009] This task is solved in the aforementioned system for temperature control of several industrial furnaces by designing the fluid line as a ring line.

[0010] Furthermore, the object of the invention is solved with the aforementioned industrial furnace arrangement, in which the system for temperature control of several industrial furnaces is designed according to the invention.

[0011] Furthermore, the object of the invention is achieved with the aforementioned method, according to which the fluid line is designed as a ring main. An advantage of this design is that the fluidic system of the plant can be made more compact by constructing the fluid line as a ring main, thus shortening the paths between the industrial furnaces. This enables the industrial furnaces to react more quickly to changing temperature requirements during a temperature control process. It also reduces heat losses during fluid transport. Moreover, the ring main design allows the fluid to be conveyed with a single conveying unit, which can then be operated more easily at its optimal performance level. In particular, the need to cycle the conveying unit between full load and various partial load levels can be avoided.This also makes it possible to reduce the energy required to operate the system. Furthermore, it can extend the service life of the conveying equipment.

[0012] To further reduce the space requirement by increasing the compactness of the system, one embodiment of the invention provides that the conveying device is at least partially arranged in the ring main.

[0013] In the preferred embodiment of the invention, the industrial furnaces are bell-type furnaces, each comprising a base and a furnace hood. By designing the industrial furnaces as bell-type furnaces, a larger number of industrial furnaces can be combined in the system, thus enabling a variety of different processes to be carried out with the industrial furnace arrangement, and generally improving the productivity of the system.

[0014] According to one design variant, it is advantageous if the connection devices are formed by the bases of the hood furnaces. This also allows for a reduction in fluid lines and thus increases the compactness of the system or the industrial furnace arrangement.

[0015] To further reduce the space required for the plant or the industrial furnace arrangement, another embodiment of the invention provides that the ring main is arranged below the connection devices.

[0016] A further improvement in the energy balance of the system can be achieved if, according to one embodiment of the invention, a closure element is assigned to each of the connection devices, with which the fluidic connection between the connection devices and the ring main can be reduced or interrupted.

[0017] To further improve this effect, the closure elements can be adjustable between an open and a closed position, with the flow path for the temperature control fluid in the annular channel being interrupted in the closed position. This allows for a reduction in transport distances in the remaining system components and, if necessary, enables a direct flow connection between two adjacent industrial furnaces.

[0018] To decouple the furnace atmosphere from the tempering fluid, one embodiment of the invention provides for heat exchangers to be arranged in the bases of the bell furnaces. This allows the industrial furnaces to be operated with different process gases. The arrangement of the heat exchangers in the industrial furnaces also shortens the flow path of the process gas.

[0019] According to another embodiment of the invention, the furnace hoods can be designed as process hoods. This also allows for decoupling the furnace atmosphere from the temperature control fluid. Furthermore, these hoods can remain on their bases throughout the entire process, from charging to unloading the industrial furnaces, thus reducing process time by eliminating the need to handle the hoods and consequently lowering energy consumption.

[0020] According to another embodiment of the invention, at least one further tubular fluid line can be arranged in the ring main. This makes it possible to heat another fluid used in the process or in a different process with the temperature control fluid, thus potentially eliminating the need for separate heating devices.

[0021] For the aforementioned reasons regarding heat exchangers in the bases, one embodiment of the method generally provides that the temperature control fluid is supplied to a heat exchanger located in the respective industrial furnace, and that a further temperature control fluid flows through the heat exchanger, exchanging heat with the temperature control fluid in the ring main and being used to temperature control the industrial furnace. For a better understanding of the invention, it is explained in more detail with reference to the following figures.

[0022] They each show, in simplified, schematic form:

[0023] Fig. 1 shows a variant of a system for temperature control of several industrial furnaces in oblique view and partially cut away;

[0024] Fig. 2 shows a variant of an industrial furnace in the form of a bell furnace;

[0025] Fig. 3 shows a cross-section through a variant of the fluid line of the system for temperature control of several industrial furnaces.

[0026] It should be noted at the outset that in the differently described embodiments, identical parts are provided with the same reference numerals or component designations, and the disclosures contained in the entire description can be applied analogously to identical parts with the same reference numerals or component designations. Furthermore, the orientation designations chosen in the description, such as top, bottom, side, etc., refer to the figure directly described and illustrated, and these orientation designations must be applied analogously to the new position if the orientation changes.

[0027] Fig. 1 shows a variant embodiment of a system 1 for temperature control of several industrial furnaces 2 (see Fig. 2).

[0028] An industrial furnace 2 is defined as a space enclosed by walls in which heat is supplied to an object, in particular to carry out processes within the object or on its surface. An industrial furnace within the meaning of the invention is, in particular, a furnace used in metallurgy or in the processing of inorganic objects or objects that are or have been manufactured exclusively from inorganic raw materials.

[0029] The term "tempering" encompasses, in particular, heating to a higher temperature, maintaining that temperature for a predefined period, and cooling to a lower temperature, generally a temperature greater than or equal to 20 °C. The term "tempering" refers to the industrial furnace 2 itself, specifically the process chamber it forms, in which at least one item is arranged for processing. Indirectly, the term "tempering" thus also refers to the at least one item.

[0030] An object (especially a metallic one) processed in industrial furnace 2 can be a product, such as a sheet or circuit board, a block, etc., or a raw material, such as a metal, etc. The process can involve, for example, melting the object or a specific reaction in, on, or with the object, such as a phase transformation, hardening of a metallic object, annealing of an object, recrystallization, etc. The object can be processed individually, or several objects can be processed simultaneously in industrial furnace 2. When processing multiple objects, they are preferably grouped into batch stacks. Coils can also be processed. These lists are merely examples and are not intended to be restrictive.

[0031] The industrial furnace 2 can be used, for example, for objects made of aluminum or an aluminum alloy, or generally non-ferrous metals or steel.

[0032] The system 1 for temperature control of several industrial furnaces 2 (hereinafter referred to simply as system 1) comprises a fluid line 3 and a conveying device 4. For better illustration of embodiments of the invention, a portion of the wall of the fluid line 3 is not shown in Fig. 1, allowing a view into a fluid channel 5 formed by the fluid line 2. However, this missing wall section is present in the fluid channel 5 during operation of the system 1.

[0033] The fluid line 3 serves to convey a temperature control fluid to the industrial furnaces 2. For this purpose, the industrial furnaces 2 are each connected to the fluid line 3 by means of at least one, preferably exclusively one, connection device 6.

[0034] As can be seen in Fig. 1, the fluid line 3 is designed as an annular channel. In principle, the annular channel can have any suitable shape. For example, the annular channel can be circular, oval, elliptical, or irregularly shaped. A rectangular, square, or generally polygonal shape for the annular channel is also possible, whereby, for flow-related reasons, the corners of polygonal designs are rounded, i.e., curved. To keep the required footprint of the system 1 as small as possible, it is preferable that the annular channel is composed of straight sections 7 and at least one curved section 8, as can be seen in the embodiment according to Fig. 1. This annular channel has two straight sections 7 arranged side by side, each with a 180° angle at one end (or both ends). 0 The arc section 8 is flow-connected.

[0035] It is also possible for the ring channel to have more than two straight sections 7 next to each other, for example by having a distribution channel arranged before the straight sections 7, from which the straight sections 7 branch off, and a collecting channel arranged after the straight sections 7, into which the straight sections 7 flow.

[0036] The described shape of the annular channel refers to the surface layer in a flow direction 9 of the temperature control fluid through or in the fluid channel 5, as indicated in Fig. 1.

[0037] The annular channel can have any suitable cross-sectional shape, at least in sections, for example, a circular, oval, elliptical, or irregular shape. A rectangular, square, or generally polygonal cross-sectional shape is also possible for the annular channel, whereby, for the reasons stated above, the corners of polygonal designs may be rounded.

[0038] The length and cross-sectional area of ​​the ring channel depend on the size of the plant 1 or on the number of industrial furnaces 2 connected to the ring channel.

[0039] The temperature control fluid is preferably a gas or a gas mixture. For example, the temperature control fluid can be air, nitrogen, hydrogen, etc.

[0040] Accordingly, the conveying device 4 is preferably a temperature-resistant (up to 650 °C) gas conveying device. For example, the conveying device 4 can be a blower, a fan, a turbine, etc. The conveying device 4 enables the conveyance of the temperature control fluid in the annular channel in the flow direction 9 and to and from the industrial furnaces 2. Since the fluid line 3 is an annular channel and there is preferably no consumption of temperature control fluid in the industrial furnaces 2, the annular channel with the industrial furnaces 2 and the conveying device 4 can also be referred to as a closed circuit.

[0041] It should be noted that while system 1 preferably has only a single conveying device 4 for conveying the temperature control fluid in the ring channel, it is also possible for more than one conveying device 4 to be arranged for conveying the temperature control fluid. For example, another conveying device 4 may be arranged to cover peak loads.

[0042] In general, the conveying device(s) 4 can be integrated into the temperature control fluid circuit via separate connecting lines. However, according to a preferred embodiment, the conveying device 4 can be arranged at least partially within the ring main. "At least partially" in this context means that at least one conveying element of the conveying device 4, such as a blower wheel, a paddle wheel, or a vane wheel, etc., is arranged within the ring main or forms part of it, as can be seen in Fig. 1, which shows a housing 10 of the conveying element of the conveying device 4. In this embodiment, the conveying device 4 is arranged in place of an arc-shaped section 8, so that the straight sections 7 are connected to each other via the conveying device 4.A drive for the conveying device 4, such as an electric motor, can be located outside the fluid channel 5.

[0043] The conveying device 4 can also be arranged at another point in the fluid line 3, for example in one of the straight sections 7.

[0044] For the integration of the conveying device 4 into the ring main (the annular channel), it can have connection elements 11 which have a cross-sectional shape corresponding to that of the fluid line 3, as shown in Fig. 1 using the example of a rectangular cross-section. One of the connection elements 11 can be part of the housing 10 of the conveying element of the conveying device 4.

[0045] In principle, a wide variety of furnaces, particularly batch furnaces, can be connected to the system 1. In the preferred embodiment of the invention, however, the furnaces are bell-type furnaces. Such bell-type furnaces are known to have a furnace hood 12 and a base 13, as shown in Fig. 2. The furnace hood 12 is designed to be removable from the base 13, which is generally fixed in place. Only the furnace hood 12 is lifted from the base 13 to provide access to a treatment chamber 14 in which the at least one item is treated. For this purpose, the at least one item is placed on the base 13, and then the furnace hood 12 is placed back on the base 13. A bell-type furnace is therefore a periodically (batch-wise), i.e., non-continuously operating, industrial furnace 2. The furnace hood 12 can, for example, have a round or polygonal shape.Accordingly, the hood can be, for example, a cylinder closed at the top or a cuboid, etc. Since these details are generally known, reference is made to the state of the art for further details and information on the operation of hood-type furnaces.

[0046] In an industrial furnace arrangement formed from Annex 1 and the industrial furnaces 2, at least two industrial furnaces 2 are arranged. Preferably, however, the industrial furnace arrangement comprises more than two industrial furnaces 2, in particular at least four industrial furnaces 2. The industrial furnace arrangement can, for example, comprise between four and ten, in particular between four and eight, industrial furnaces 2. Annex 1 can comprise a number of connection devices 6 corresponding to the number of industrial furnaces.

[0047] Within the scope of the invention, it is also possible that different industrial furnaces 2, in particular those to be operated discontinuously, are combined with each other in the industrial furnace arrangement.

[0048] The connection devices 6 for the industrial furnaces 2 can, for example, be pipelines that are integrated into the ring main on one side and connected to the flow of the respective industrial furnace 2 on the other. According to one embodiment of the invention, in the case of bell furnaces as industrial furnaces 2, the connection device(s) 6 can be formed by the bases 13 of the bell furnace(s), as shown schematically in Fig. 1. For the sake of clarity, a more detailed description of the bases 13 has been omitted. In this regard, reference is made to Fig. 2, or rather, bases 13 are known in the prior art for bell furnaces, so that reference is also made to this prior art for details.

[0049] As is known, several hoods are used for the operation of a bell-type furnace, such as an inner protective hood, a heating hood, a cooling hood, etc. In the embodiment of a bell-type furnace shown in Fig. 2, the furnace hood 12 is designed as a process hood. The process hood rests on the base 13 during the process, i.e., the treatment of the at least one object. For example, an end face 15 of the process hood rests fully and tightly against a surface 16 of the base 13, optionally with an intermediate gasket. The term "process hood" is intended to express that the hood of the bell-type furnace remains on the base 13 during the entire temperature treatment of the at least one object.The process hood can remain in place and no further hood is arranged above this process hood for individual treatment stages, such as heating the object with a heating hood or cooling the object with a cooling hood. The process hood is therefore preferably the only furnace hood 12 used on the hood furnace.

[0050] The process hood has an inner shell 17 to which thermal insulation 18 is arranged and, in particular, connected. Preferably, the process hood also has a protective shell 19 (also referred to as an outer shell) such that the thermal insulation 18 is arranged between the inner shell 17 and the protective shell 19.

[0051] To create a flow of the process fluid, in particular the protective gas, in the treatment chamber 14 and to redistribute the thermal energy, a fan 20 or a turbine can be provided in the base 13, with which the gaseous medium is circulated in the treatment chamber 14. The base 13 can further include a heating device for heating the process fluid.

[0052] The fan 20 can be driven by a fan motor 21, which is preferably located below the fan wheel.

[0053] The heating device of the base 3 is preferably an electric heating device, i.e., in particular a heating device with resistance heating elements.

[0054] If the hood furnace is not operated with a process hood, a heating hood can also be used to heat the process fluid.

[0055] The heating hood or process hood can (additionally) also be equipped with gas firing or an additional electric heating element, which is, for example, arranged in the casing of the furnace hood 12. In general, the industrial furnace 2 or the industrial furnaces 2 can be equipped with a heating device.

[0056] The heating element of the industrial furnace 2, located in the bases 13 of the bell-shaped furnaces, heats the process fluid. The additional heating element in the bell serves to heat another gas, which then partially transfers its heat to the protective hood of the bell-shaped furnace or the inner shell 17 of the process hood, thus contributing to the heating of the process fluid and at least one object. The protective hood of the bell-shaped furnace or the inner shell 17 of the process hood, together with the base 13, seals the treatment chamber 14, preventing the additional gas from coming into contact with the process fluid. The process hood can be designed with a fluid guide channel to direct the additional gas, which can extend completely around the inner shell 17. This can be achieved by spacing the thermal insulation 18 from the inner shell 17.If necessary, a gas guide cylinder is arranged at least section by section between the inner shell 17 and the thermal insulation 18 to form the gas guide channel.

[0057] To enable partial reuse of the thermal energy, system 1 is provided, which transfers at least some of the thermal energy released during the cooling of an industrial furnace 2 to another industrial furnace 2 in the industrial furnace arrangement containing the temperature control fluid, and reuses it there for the indirect heating of the process fluid or at least one object. Depending on the desired temperature level, heating with the temperature control fluid may be sufficient, or supplemental heating with the heating element of industrial furnace 2 may be necessary.

[0058] To enable this, in the design of the industrial furnaces 2 as bell furnaces, the channel formed around the protective hood of a bell furnace, which is created by the spacing of the further hood that is arranged above the protective hood, or in the case of the aforementioned process hood, its fluid guide channel, can be or become flow-connected with the ring main, i.e., the fluid channel 5. The further gas can in this case be the aforementioned temperature control fluid.

[0059] Depending on the process to be carried out in the industrial furnace 2, the thermal energy can either be introduced directly into the industrial furnace 2 via the temperature control fluid or alternatively transferred to the process fluid of the industrial furnace 2 via at least one heat exchanger 22. Direct inflow of the temperature control fluid into the treatment chamber 14 of the industrial furnace 2 is particularly possible if the temperature control fluid is identical to the process fluid. In contrast, the at least one heat exchanger 22 can also be used to separate the temperature control fluid and the process fluid, for example, for processes involving oxidation-sensitive objects when Euft is used as the temperature control fluid, as can also be achieved in the preferred embodiment of the invention with the fluid guide channel on the protective hood or in the process hood, as described above. In these latter embodiments, the heat exchanger 22 is preferably not present.This space can be used as a transfer channel for the temperature control fluid from the ring main into the fluid guide channel.

[0060] The heat exchanger 22 can carry a further temperature control fluid, which is in heat exchange with the temperature control fluid in the ring main and is used to control the temperature of the industrial furnace 2. This further temperature control fluid is preferably the process fluid used for the process to be carried out in the respective industrial furnace 2. The arrangement of at least one heat exchanger 22 also makes it easier to combine industrial furnaces 2 in the industrial furnace arrangement, in which different processes are to take place simultaneously. With the design of the industrial furnace 2 incorporating the heat exchanger 22, the channel between the hoods or the fluid guide channel in the process hood can therefore be omitted.

[0061] In the design of the industrial furnace 2 or the industrial furnaces 2 as a hood furnace / hood furnaces, at least one heat exchanger 22 can be arranged in the base 13, as shown in Fig. 2.

[0062] The heat exchanger 22 can, for example, be designed as a shell-and-tube heat exchanger, which can have heat exchanger tubes running the entire circumference. Instead of a full circumference, several (shell-and-tube) heat exchangers 22 can also be arranged one behind the other in the circumferential direction of the base 13 to vary the performance. The heat exchanger tubes can be surrounded on the outside by the temperature control fluid from the ring main.

[0063] At least one heat exchanger 22 can also be designed differently or be arranged at a different location in the industrial furnace arrangement.

[0064] Due to its arrangement in the base 13, the process hood, or more generally the furnace hood 12, can be designed more simply and, in particular, can also be free of any additional tubular fluid lines within the hood, etc. The supply of media to the heat exchanger 22, and generally also the supply of the hood furnace with electrical energy, various media, etc., can be provided exclusively via the base 13, which is usually stationary.

[0065] Preferably, as shown in Fig. 1, the ring main is arranged at least partially, and in particular entirely, below the connection devices 6, especially the base 13, according to one embodiment. In principle, however, the ring main can also be arranged next to the industrial furnaces 2.

[0066] For at least three, and in particular at least four, industrial furnaces 2, it can be advantageous if at least one or some of the industrial furnaces 2 are disconnected from the ring main for a predetermined period, for example, during a constant temperature phase of the process, i.e., if the fluid connection to the ring main is disconnected. It can also be advantageous if not only the fluid connection can be interrupted, but also the volume flow of temperature control fluid to the industrial furnace 2(s) 2 can be varied, in particular, controlled. For such applications, according to one embodiment of Annex 1, it can be provided that each of the connection devices 6 is assigned a closure element 23, which is adjustable between an open and a closed position, so that the fluidic connection between the connection devices 6 and the ring main can be reduced or interrupted.According to a further embodiment of Annex 1, this closure element 23 can be a slide or, in particular, a flap. These can be arranged to close the connection devices 6, for example, the underside of the bases 13. According to another embodiment of Annex 1, in the closed position of the closure elements 23, the flow path for the temperature control fluid in the annular channel itself can be interrupted, as shown in Fig. 1.

[0067] The locking elements 23 can also be designed differently, as long as the effect described above is achieved.

[0068] The locking elements 23 can be designed to be adjustable individually or in groups.

[0069] Figure 3 shows another embodiment of the system 1, in particular a cross-section through fluid line 3. In this embodiment, at least one further tubular fluid line 24 is arranged in the fluid line 3, i.e., in the ring main. As Figure 3 shows, a bundle of further tubular fluid lines 24 can be arranged in the fluid channel 5. This at least one further fluid line 24 can be supplied with a gaseous or liquid fluid via further fluid connections 25, so that heat exchange takes place between the temperature control fluid and the further fluid. This allows, for example, additional waste heat from other processes to be fed into the system 1. Likewise, excess heat can be extracted from the system 1 and made available for other processes. In addition, this allows another fluid, which is required for a process in one of the industrial furnaces 2 of the industrial furnace arrangement, to be preheated or cooled.be heated.

[0070] The exemplary embodiments show or describe possible embodiment variants of the invention, whereby it should be noted at this point that combinations of the individual embodiment variants are also possible.

[0071] Finally, for the sake of clarity, it should be noted that, for a better understanding of the structure of Annex 1 and its components, these are not necessarily shown to scale.

[0072] Reference numeral list

[0073] Attachment

[0074] industrial furnace

[0075] Fluid line

[0076] Funding institution

[0077] Fluid channel

[0078] Connection device

[0079] Section

[0080] Section

[0081] Flow direction housing

[0082] Connection element

[0083] Oven hood

[0084] base

[0085] Treatment chamber

[0086] Front surface

[0087] surface

[0088] inner liner

[0089] thermal insulation

[0090] Protective cover

[0091] fan

[0092] fan motor

[0093] Heat exchanger

[0094] Fluid line closure element

Claims

Patent claims 1. Plant (1) for temperature control of several industrial furnaces (2) comprising a fluid line (3) and a conveying device (4) for conveying a temperature control fluid to the industrial furnaces (2), and with connection devices (6) for fluidic connection of the industrial furnaces (2) to the fluid line (3), characterized in that the fluid line (3) is designed as a ring line.

2. Plant (1) according to claim 1, characterized in that the conveying device (4) is at least partially arranged in the ring main.

3. Plant (1) according to claim 1 or 2, characterized in that the industrial furnaces (2) are hood furnaces, each having a base (13) and a furnace hood (12).

4. Plant (1) according to claim 3, characterized in that the connection devices (6) are formed by the bases (13) of the hood ovens.

5. System (1) according to one of claims 1 to 4, characterized in that the ring line is arranged below the connection devices (6).

6. System (1) according to one of claims 1 to 5, characterized in that each of the connection devices (6) is assigned a closure element (23) with which the fluidic connection between the connection devices (6) and the ring line can be reduced or interrupted.

7. System (1) according to claim 6, characterized in that the closure elements (23) are adjustable between an open position and a closed position, wherein in the closed position the flow path for the temperature control fluid in the annular channel is interrupted.

8. Plant (1) according to one of claims 3 to 7, characterized in that at least one heat exchanger (22) is arranged in each of the bases (13) of the hood ovens.

9. Annex (1) according to any one of claims 3 to 8, characterized in that the Oven hoods (12) are designed as process hoods.

10. Plant (1) according to one of claims 1 to 9, characterized in that at least one further tubular fluid line (24) is arranged in the ring line.

11. Industrial furnace arrangement comprising several industrial furnaces (2) and a system (1) for temperature control of the several industrial furnaces (2) which is flow-connected to the industrial furnaces (2), characterized in that the system (1) for temperature control of the several industrial furnaces (2) is formed according to one of claims 1 to 10.

12. Method for temperature control of several industrial furnaces (2) with a system (1) for temperature control of the several industrial furnaces (2), which has a fluid line (3) and a conveying device (4) with which a temperature control fluid is conveyed to the industrial furnaces (2), and with connection devices (6) with which the industrial furnaces (2) are fluidically connected to the fluid line (3), characterized in that the fluid line (3) is designed as a ring line.

13. Method according to claim 12, characterized in that a system (1) for temperature control of the several industrial furnaces (2) is used, which is designed according to one of claims 1 to 11.

14. Method according to claim 12 or 13, characterized in that the temperature control fluid is supplied to a heat exchanger (22) which is arranged in the industrial furnace (2), and that a further fluid flows through the heat exchanger (22) which is in heat exchange with the temperature control fluid in the ring line and which is used for temperature control of the industrial furnace (2).

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