EP2791606B1 - Closed transport fluid system for furnace-internal heat exchange between annealing gases - Google Patents

Description

The invention relates to an oven for heat treating annealing material and a method for heat treating annealing material in an oven.

AT 508776 discloses a method for preheating Glühgut in a Bebelglühanlage with the annealed under a protective hood in a transport fluid atmosphere receiving Glühsockeln. The annealing material to be subjected to a heat treatment in a protective cover is preheated with the aid of a gaseous heat carrier, which circulates the protective hoods from the outside in a cycle and absorbs heat from a heat-treated annealing material in a protective hood and delivers it to a pre-heated annealing material in another protective hood. For the heat treatment of the annealing material, at least one additional incandescent base is used with a protective hood which can be heated from outside via burners. The hot exhaust gases from the heater of this guard are added to the heated heat carrier for preheating the annealing.

AT 507423 discloses a method for preheating Glühgut in a Bebelglühanlage with two the Glühgut under a protective cap receiving Glühsockeln. The annealing material to be subjected to a heat treatment in a protective cover is preheated with the aid of a gaseous heat carrier, which is circulated between the two protective hoods and absorbs heat from a heat-treated annealing stock in a protective hood and delivers it to the annealing stock to be preheated in the other protective hood. The recirculated heat transfer fluid flows around the two protective hoods from the outside, while a transport fluid is circulated inside the protective hoods.

AT 411904 discloses a bell annealing furnace, in particular for steel band or wire coils, with a Glühsockel receiving the Glühgut and with a gas-tight patch guard. Further is a radial fan mounted in the glow base is provided, which comprises an impeller and a rotor surrounding the impeller for circulating a transport fluid in the protective hood. A heat exchanger for cooling the transport fluid is connected on the input side via a flow channel to the pressure side of the radial fan and opens on the output side into an annular gap between the distributor and the protective hood. An axially displaceable in the pressure-side flow path of the radial fan deflection serves to selectively connect the heat exchanger (water-cooled annular tube bundle) leading flow channel to the radial fan. The protective cover is gas-tightly mounted on an annular flange, namely pressed against the base flange. The heat exchanger (radiator) is located below the annular flange. The flow channel consists of an outgoing from the outer periphery of the nozzle, concentric with the annular gap annular channel. The deflection device is designed as a ring surrounding the outside, annular deflecting slide.

SU 1740459 A1 discloses a hood furnace having two sealed furnace chambers. Outside the furnace chambers, a heat exchanger is arranged. The heat exchanger is coupled to the furnace chambers, so that by means of the heat exchanger thermal energy can be discharged from one furnace chamber to the other furnace chamber and vice versa.

US 2,479,102 A discloses a bell annealing furnace, in the inner volume of which coils or sheet-like material are stacked and heated. In the upper portion of the bell annealing furnace, a heat exchanger assembly is shown having tubes extending in concentric loops about the central axis of the bell annealing furnace. In a heating mode, combustion gas is flowed through the heat exchanger tubes to heat the gas or inner atmosphere within the hood annealing furnace, and in a subsequent cooling mode, air is passed through the heat exchanger tubes.

Conventional batch furnaces have a relatively high energy consumption.

It is an object of the present invention to operate a batch furnace in an energy efficient manner.

This object is solved by the objects with the features according to the independent claims. Further embodiments are shown in the dependent claims.
According to an embodiment of the present invention, a furnace for heat treating annealing material is provided. The furnace has a closable first furnace space, which is designed for receiving and for heat treating annealing material by thermal interaction of the annealing with heatable first annealing gas in the first furnace chamber. In the first furnace chamber is a first heat exchanger arranged, which is designed for the thermal exchange between the first annealing gas and a transport fluid. The first heat exchanger is arranged within a housing section (for example within a protective hood, in particular within an innermost protective hood) of the first furnace chamber. This housing section encloses the first annealing gas in the interior of the first furnace chamber (in particular, this housing section, which receives annealing material, is in direct contact with the first annealing gas and seals it hermetically or gas-tight from the environment). Furthermore, a closable second furnace space is provided, which is designed for receiving and for heat treating Glühgut by means of thermal interaction of the Glühguts with heatable second annealing gas in the second furnace chamber. In the second furnace chamber, a second heat exchanger is arranged, which is designed for thermal exchange between the second annealing gas and the transport fluid. The second heat exchanger is arranged within a housing section (for example within a protective hood, in particular within an innermost protective hood) of the second furnace chamber. This housing section encloses the second annealing gas in the interior of the second furnace chamber (together with annealing stock) (in particular, it receives the annealed material in direct contact with the second annealing gas and seals it hermetically against the environment). A closed transport fluid path is operatively connected to the first heat exchanger and to the second heat exchanger such that thermal energy can be transferred between the first annealing gas and the second annealing gas by means of the transport fluid.

According to yet another exemplary embodiment of the invention, a method is provided for heat treating annealing material in a furnace, wherein in the method annealing material is received in a closable first furnace chamber and by means of thermal Interaction of the annealing with heatable first annealing gas in the first furnace chamber is heat treated. Furthermore, a thermal exchange between the first annealing gas and a transport fluid is effected by means of a first heat exchanger arranged in the first furnace chamber. The first heat exchanger is arranged within a housing section of the first furnace chamber. This housing section encloses the first annealing gas inside the first furnace chamber. Annealed material is received in a closable second furnace space and heat-treated by means of thermal interaction of the annealing with heatable second annealing gas in the second furnace chamber. In addition, a thermal exchange between the second annealing gas and the transport fluid is effected by means disposed in the second furnace chamber second heat exchanger, wherein the second heat exchanger is disposed within a housing portion of the second furnace chamber. This housing section includes the second annealing gas inside the second furnace space. A closed transport fluid path, which is operatively connected to the first heat exchanger and to the second heat exchanger, is controlled such that thermal energy is transferred between the first annealing gas and the second annealing gas by means of the transport fluid.

According to an exemplary embodiment of the invention, a fluidic path provided separately from the annealing gas in various sockets or furnace spaces of a furnace, also referred to as a closed transport fluid path, can be provided which are provided with respective heat exchangers (which are separate from protective covers, in particular in their interior). in the furnace chambers operatively connected to exchange thermal energy between two separate annealing gases in the two furnace chambers. It is important that a direct mechanical contact between the transport fluid and the annealing gas is avoided in the furnace chambers. Only a thermal exchange between these gases or fluids is made possible by means of the respective heat exchanger. In this way, in an oven having a plurality of oven compartments or sockets, for example, thermal energy of a furnace chamber currently in a cooling phase can be used to preheat another furnace chamber currently in a heating phase. For this purpose, according to the invention, a separate and closed transport fluid path is provided, which is brought into fluid communication with the heat exchangers arranged inside the furnace chambers (which are therefore in each case completely enveloped, ie in full flow, by the respective annealing gas). This leads to an efficient use of the energy used. In this case, the annealing gas of a base (for example, 100% hydrogen) with the annealing gas of the heat exchanging partner socket (for example, also 100% hydrogen) does not come into contact. Thus, an undesirable loss of quality due to carbon fouling (by evaporating rolling oils or drawing agents) or the unwanted supply of traces of oxygen (O ₂ ) and water (H ₂ O) during heating of the heat exchanger is reliably avoided. Furthermore, the safety of the furnace according to the invention is very high, since the interaction between annealing gas different furnace spaces or between annealing gas on the one hand and transport fluid (for example, 100% hydrogen or 100% helium) on the other hand, despite the provision of the heat exchanger is prevented.

Although the transport fluid path is fluidically, but not thermally, decoupled from the annealing gas in the two furnace chambers, it is also possible to design the transport fluid used specifically for the needs of efficient heat transfer out, in particular to use a transport fluid of high thermal conductivity. For example, 100% H2, 100% He or other good heat-conducting gases can be used. Moreover, it is in such a fluidic Decoupling of annealing gas and transport fluid possible to design the transport fluid path as a high pressure path, so that in the pressurized transport fluid transport significantly increased heat transfer and at the same time a particularly high amount of heat can be transported without the relatively low pressure gas ratios in the individual furnace chambers would be undesirable ,

In addition to the heat exchange of thermal energy stored in the annealing gas of the individual furnace chambers, the transport path can also be used for providing heating or cooling energy for selectively heating or cooling a respective one of the furnace spaces. Crucial for the transport fluid path is that it acts directly in full flow. Thus, the transport fluid path according to the embodiment of the invention can be used both for heat exchange between different furnace chambers, as well as for heating or cooling.

If according to one embodiment exactly only one heat-insulated protective cover (without the compulsory requirement of providing further heating or cooling hoods) is placed on the respective base, the arrangement can be made very compact. This advantage is made possible by positioning the heat exchangers as the only heat supply units for the respective annealing gas inside the annealing space (ie under the protective hood). Furthermore, the expense associated with the necessary Kranspielen for handling the individual hoods is significantly reduced in the absence of heating or cooling hoods. Essentially, a crane is only needed to transport glowglove racks as well as the protective hoods to the furnace rooms, no longer to maneuver cooling or heating hoods.

In the following, additional exemplary embodiments of the furnace will be described. These also apply to the procedure.

According to one embodiment, the oven may be configured as a batch-operable oven, in particular as a hood oven or chamber oven. A batch oven is understood to mean a stove into which a set of annealed material, for example heat-treated tapes, is introduced. Then the corresponding furnace chamber is closed and subjected to the batch introduced Glühgut the heat treatment. In other words, a batch oven is a batch oven.

According to an embodiment, the first furnace space may be closable with a detachable first guard (as the above-mentioned housing portion of the first furnace space) and the second furnace space with a removable second guard (as the above-mentioned housing portion of the second furnace space) can be closed. The respective thermally insulated protective cover for the furnace chamber can be designed so that it hermetically seals the interior of the furnace chamber or gas-tight, so that an annealing gas which can be introduced into the respective furnace chamber is reliably protected from flowing out of the respective furnace chamber.

According to one embodiment, the first protective hood may be the outermost, in particular the only, hood of the first furnace chamber. The second protective hood may be the outermost, in particular the only, hood of the second furnace chamber. According to this preferred embodiment, the oven can be equipped with a single hood per oven space. Compared to conventional hood ovens, in which a protective hood and in addition an external heating or cooling hood is placed, the inventive construction of the furnace with a single protective cover per socket is much easier. These Simplification of the design results from the positioning of the respective heat exchanger in the furnace chamber and in fluid communication with the transport fluid path, since this heat exchanger can take over the entire thermal coupling between the annealing gas and the transport fluid and thus all heating and cooling tasks. Embodiments of the invention are thus feasible with minimal space requirements, since no heating hood, no cooling hood, no exchange hood is required, and each socket a single thermally insulated guard may be sufficient.

According to one exemplary embodiment, the first protective hood and the second protective hood can each have a heat-resistant inner housing, in particular made of a metal, and an insulating sheath of a heat-insulating material. Since the energy supply according to this embodiment no longer takes place via the protective hood (for example burner of the heating hood from the outside), the wall temperature of the protective hoods is lower, the heat-resistant material is less stressed and the wall heat losses decrease. According to this embodiment, the hood for hood furnaces can be designed significantly different than conventional protective hoods. While the conventional protective hoods are to be formed consistently from a thermally highly conductive material in order to achieve a thermal balance between the annealing gas under the respective protective hood and another gas between the two hoods, is taken into account in the described embodiment of the fact that a thermal Interaction through the protective cover is no longer necessary and no longer desired. For this reason, the guard may be at least partially formed of a thermally insulating material to suppress heat loss to the outside.

On the other hand, the protective hood and / or the further protective hood can in an embodiment of the furnace as a chamber furnace each have a not necessarily heat-resistant outer housing, in particular of a metal, and an inner insulating jacket of a heat-insulating material.

According to an embodiment, the transport fluid path may include a heating unit for generating heating heat. The heating unit may be configured to directly heat the transport fluid or the first heat exchanger or the second heat exchanger. By means of thermal transfer of the generated heating heat to the first annealing gas, the first furnace space can be heated. Alternatively or additionally, by means of thermal transfer of the generated heating heat to the second annealing gas, the second furnace space can be heated. The heating unit may be outside the oven rooms, i. outside the heated area. If the transport fluid path is coupled to a separate heating unit, the transport fluid itself can not only serve for the heat exchange between the annealing gas in the different furnace chambers, but can also transport thermal energy from the heating unit into the interior of the respective furnace space.

In another embodiment, with an electrical supply unit (for example comprising a transformer) and the tube bundle itself can be used or used as transmission medium for electric current which (preferably at low voltage and high current) by ohmic losses (according to the principle of electrical resistance heating ) can be converted into heat energy in the respective heat exchanger. As a corresponding coupling element, for example, a low-resistance pipe wall of the transport fluid path can be used, to which the respective heat exchanger (in particular a tube bundle) is connected. Passing the coupling element through a floor or a furnace base of the furnace chamber makes it possible to form the protective cover easily and without interruption, since it is unnecessary to pass a supply line to the heat exchanger through the protective hood.

By contrast, when using a gas heating unit, it may be preferable to heat the transport fluid itself and to bring it by fans along the transport fluid path for thermal interaction via the respective heat exchanger with the annealing gas inside the respective furnace space.

This annealing chamber external heating unit may be, for example, a gas heating unit, an oil heating unit, a pelletizing unit or an electric heating unit. The heating e.g. with gas can take place via a glühkammerexternen heat exchanger, the tube bundle heat, for example using natural gas burners, the hot gas pressure, which can be transported with a pressure fan to the respective annealing gas chamber heat exchanger. The heating with electrical energy can also be done via a transformer directly through the tube bundle of the combustion chamber external heat exchanger to transfer electrical energy to the hot gas pressure and to convey the thermal energy contained therein to the respective Glühgaskammerwärmetauscher.

Furthermore, the oven is environmentally friendly operable, for example, because in an electric heating unit (internal or external) no carbon dioxide and no nitrogen oxides are generated. With the described very effective heat exchange in a gas heating, the methane consumption is low, so that only small amounts of CO ₂ and NO _x arise. An oil heating unit may burn oil to generate thermal energy. A pelletizing unit can fire wood pellets to generate thermal energy. Of course there are other species of thermal energy generating units according to the invention can be used.

According to one embodiment, the first furnace chamber may be closable with a removable first heating hood, which encloses the first protective hood. The second furnace chamber can be closed with a removable second heating hood, which encloses the second protective hood. According to an exemplary embodiment, the first furnace chamber may have a first heating unit for heating a gap between the first heating hood and the first protective hood. Correspondingly, the second furnace chamber may have a second heating unit for heating a gap between the second heating hood and the second protective hood. According to this embodiment, a further heating hood per base or oven space is provided in addition to the protective hood. This serves to heat a gap between the heating hood and the protective hood, in which case a thermal compensation through the protective hood leads to a heating of the annealing gas. In this embodiment, the transport fluid path can be provided exclusively for exchanging thermal energy between the annealing gases. It is also possible to place a cooling hood on the respective furnace chamber, thereby initiating a cooling of the annealing gas.

According to this embodiment, the first heating unit and the second heating unit may each be a gas heating unit. Such a gas heating unit may be a gas burner, which heats between the heating and protective hood.

According to one embodiment, the first heat exchanger and / or the second heat exchanger may be configured as a tube bundle heat exchanger made of tubes bent into a bundle. A shell-and-tube heat exchanger can be understood to mean a heat exchanger that passes through a bundle of tubes is formed, which are wound, for example, circular. The tube interior can be part of the transport fluid path and can be flowed through by the transport fluid. The tube outer can be brought directly into contact with the respective annealing gas. In particular, a shell-and-tube heat exchanger can be formed from tubes arranged parallel to each other. The pipe wall can be gas-tight and heat-resistant. The arrangement may be configured such that the transport fluid is forced or conveyed through the interior of the tubes and separated from the respective annealing gas through the tube wall. Through the bundle of tubes, a large effective thermal exchange surface can be provided so that the transport gas and the respective annealing gas can exchange a large amount of thermal energy. Furthermore, embodiments of the invention can be used in a fully automatic mode.

According to the invention, a tube bundle can be used as a heat exchanger in the individual furnace chambers, which can be set in the full flow. This then serves to heat exchange between a cooling charge of Glühgut and an annealing batch of Glühgut. Furthermore, with the tube bundle heat exchangers can be heated to annealing temperature. Cooling to a final temperature (for example, a discharge temperature of the Glühguts) can be carried out by means of the same shell and tube heat exchanger.

According to one exemplary embodiment, the first furnace chamber may have a first annealing gas fan and the second furnace chamber may have a second annealing gas fan, wherein the respective annealing gas fan is set up to direct the respective annealing gas to the respective heat exchanger and to the respective annealing stock. A respective Glühgasventilator can be arranged in a lower region of the respective base or furnace chamber and can circulate the annealing gas to it in good bring thermal interaction with annealing in the respective furnace chamber. The respective Glühgasventilator can steer for this purpose, the annealing gas by means of a nozzle in a particular direction.

According to one embodiment, the transport fluid may be a good heat-conductive transport gas, in particular hydrogen or helium. In general, the transport fluid may be a liquid or a gas. When using hydrogen or helium, use can be made of their good thermal conductivity. In addition, these gases are well used even under high pressure.

According to one embodiment, the transport fluid in the transport fluid path may be under a pressure of about 2 bar to about 20 bar or higher, in particular under a pressure of about 5 bar to about 10 bar. Thus, a significant overpressure of the transport fluid to atmospheric pressure can be generated, which can go beyond the only slight overpressure may be exposed to the annealing gas in the furnace. By using high pressure in the heat exchanger, the heat exchange can be made particularly efficient, without a high-pressure capability in the first and second furnace chamber would be required.

In one embodiment, the transport fluid in the transport fluid path may be brought to a temperature in a range between about 400 ° C and about 1100 ° C, more preferably in a range between about 600 ° C and about 900 ° C. For example, the transport fluid in the transport fluid path may be brought to a temperature in a range between 700 ° C and 800 ° C. Thus, by means of the transport fluid temperatures can be generated in the furnace chambers, which are required for the treatment of Glühgut, such as tapes or wires or profiles of steel, aluminum or copper and / or their alloys.

According to one embodiment, the furnace may further comprise at least one sealable third furnace space adapted to receive and heat anneal by thermally interacting the anneal with heatable third annealing gas in the third furnace space and a third heat exchanger disposed in the third furnace space thermal exchange between the third annealing gas and the transport fluid is formed. The third heat exchanger can also be arranged within a housing section of the third furnace chamber, which housing section encloses the third annealing gas in the interior of the third furnace chamber. The closed transport fluid path can also be operatively connected to the third heat exchanger such that thermal energy can be transferred between the first annealing gas and the second annealing gas and the third annealing gas by means of the transport fluid. According to this embodiment, at least three furnace rooms can be coupled together. Then, an energy-exchanging heating, a heating and a cooling cycle can be distinguished for each one of the furnace rooms. Cyclically, two of the three furnace chambers may be thermally coupled by the transport fluid, for example to pre-cool one furnace and preheat the other. The third oven may then be subjected to a heating or cooling procedure. The heat exchange between the furnace chambers can be provided in several stages with the use of two furnace chambers in one stage, with the use of three furnace chambers in two stages or with the use of more than three furnace chambers.

According to one embodiment, the furnace may include a control unit configured to control the transport fluid path such that by thermal exchange between the transport fluid and the first annealing gas and the second annealing gas selectively one of the first furnace space and the second furnace space in a preheat mode, a heating mode , a pre-cooling mode or a Final cooling mode is operable. Such a control unit may for example be a microprocessor which coordinates the operation of the different furnace spaces. In this case, the control unit may, for example, control the heating unit, the cooling unit or valves of the fluidic system in order to carry out an automated operation. A preheating mode can be understood as an operating mode of a furnace chamber in which a hot gas is brought to an elevated intermediate temperature by supplying thermal energy of another hot gas to the hot gas. An annealing gas may be subjected to one or more consecutive preheating phases. In a heating mode, an oven-external heating unit (gas, electric, etc.), which has already been preheated in the above-mentioned single or multi-stage annealing gas, can be switched on in order to bring the annealing gas to a high final temperature. After completion of the heating mode and before the start of a cooling mode, an annealing gas may be subjected to precooling (quasi the inverse process to above preheating) in which the annealing gas is brought to a lowered intermediate temperature by passing the annealing gas thermal energy to another annealing gas via the transport fluid gas indirectly feeds. In a final cooling mode, an off-gas cooling unit (for example water cooling) can be connected to the fluid gas and thus to the annealing gas in order to cool the annealing gas to a lower temperature.

In one embodiment, the transport fluid path may include a transport fluid fan for conveying the transport fluid through the transport fluid path. The transport fluid fan can thus promote the transport fluid along predetermined paths, which can be predetermined by corresponding valve positions.

In one embodiment, the transport fluid path may include a switchable radiator for cooling the transport fluid in the transport fluid path. Such a switchable cooler (for Example based on the principle of water cooling a tube bundle) allows to apply to the transport fluid with cooling energy, which can be coupled via the respective heat exchanger in the individual furnace chambers.

1. a) einem ersten Betriebsmodus, bei dem der Transportfluidventilator das Transportfluid mit dem zweiten Glühgas thermisch koppelt, so dass das Transportfluid dem zweiten Glühgas Wärme entnimmt und dem ersten Glühgas zuführt, um den ersten Ofenraum vorzuheizen und den zweiten Ofenraum vorzukühlen;
2. b) einem nachfolgenden zweiten Betriebsmodus, bei dem eine Heizeinheit den ersten Ofenraum weiterheizt, und bei dem in einem davon getrennten Pfad der Transportfluidventilator das Transportfluid dem zugeschalteten Kühler zum Kühlen zuführt und das gekühlte Transportfluid mit dem zweiten Glühgas thermisch koppelt, um den zweiten Ofenraum weiterzukühlen;
3. c) einem nachfolgenden dritten Betriebsmodus, bei dem der Transportfluidventilator das Transportfluid mit dem ersten Glühgas thermisch koppelt, so dass das Transportfluid dem ersten Glühgas Wärme entnimmt und dem zweiten Glühgas zuführt, um den zweiten Ofenraum vorzuheizen und den ersten Ofenraum vorzukühlen;
4. d) einem nachfolgenden vierten Betriebsmodus, bei dem die Heizeinheit den zweiten Ofenraum weiterheizt, und bei dem in einem davon getrennten Pfad der Transportfluidventilator das Transportfluid dem zugeschalteten Kühler zum Kühlen zuführt und das gekühlte Transportfluid mit dem ersten Glühgas thermisch koppelt, um den ersten Ofenraum weiterzukühlen.

In one embodiment, the transport fluid path may include a plurality of valves. The valves can be, for example, pneumatic valves or solenoid valves that can be switched by means of electrical signals. When the valves are suitably arranged in the fluidic path, different operating modes can be set. The valves may be switchable (for example, under control of a control unit) such that the furnace is selectively operable in one of the following modes of operation:

1. a) a first mode of operation in which the transport fluid fan thermally couples the transport fluid to the second annealing gas so that the transport fluid removes heat from the second anneal gas and supplies it to the first annealing gas to preheat the first furnace space and pre-cool the second furnace space;
2. b) a subsequent second mode of operation in which a heating unit continues to heat the first furnace space, and wherein in a separate path the transport fluid fan supplies the transport fluid to the switched-on cooler for cooling and thermally couples the cooled transport fluid with the second annealing gas to further cool the second furnace space ;
3. c) a subsequent third mode of operation in which the transport fluid fan thermally couples the transport fluid to the first annealing gas so that the transport fluid removes heat from the first annealing gas and supplies it to the second annealing gas to preheat the second furnace space and to pre-cool the first furnace space;
4. d) a subsequent fourth mode of operation, in which the heating unit continues to heat the second furnace space, and in a said separate path of the transport fluid fan feeds 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 space.

These four modes of operation can be successively repeated so that a cyclic process can be run through.

According to one embodiment, the heat exchanger may be designed to be flameproof in the furnace or have a pressure vessel which encloses at least a portion of the transport fluid path pressure-tight. For example, the entire transport fluid path, which may be operated under high pressure of, for example, 10 bar, may be constructed with pressure resistant tubes, valves, and transport fluid fans or housed in a pressure vessel or other pressure protection device. But it is also possible, particularly pressurized components, in particular the transport fluid fan to coat with a pressure vessel.

According to an embodiment, the first heat exchanger may be arranged relative to a first Glühgasventilator for driving the first Glühgases and / or the second heat exchanger relative to a second Glühgasventilator for driving the second Glühgases such that in each operating state of the furnace driven by the first Glühgasventilator first Milled gas flows through the first heat exchanger and / or that in each operating state of the furnace or of a respective furnace chamber, the second annealing gas driven by the second annealing gas fan flows through the second heat exchanger.

A significant advantage of such an embodiment is that in any operating condition (in particular for heating by means of a heater, for cooling by means of a cooling device and for heat exchange between annealing gas and heat exchange device) directed by the fan mulled gas is directed directly to the respective heat exchanger. Such a direct or direct flow with a fan gas-driven annealing gas can in particular be carried out in full flow, ie, completely along a circumference (for example of an imaginary circle) around the fan. As a result, a very efficient heat coupling between annealing gas and the respective heat exchanger can be achieved. The respective heat exchanger can in particular be fixedly mounted or immovably provided on the furnace, in order to ensure that the annealing gas conveyed by the fan is directed via baffles or the like to an approximately circularly arranged tube bundle heat exchanger or another heat exchanger. In order to ensure that in each operating state of the furnace or of a respective furnace chamber the respective annealing gas driven by the respective annealing gas fan flows through the respective heat exchanger, the respective heat exchanger is to be arranged fixedly and immovably at a corresponding point of the furnace or permanently fixed there. As the possible operating conditions of the furnace or a respective furnace space, a heating operating state for heating by means of a heating unit, a cooling operating state for cooling by means of a cooling unit, and a heat exchange operating state for exchanging heat between different furnace spaces using the transport fluid path (for preheating or Precooling).

According to one embodiment, in the furnace, the first annealing gas and the second annealing gas may remain contactless with respect to the transport fluid. Thus, it can be ensured constructively that the annealing gas does not come into contact with the transport fluid gas, so that no sooting occurs.

• Fig. 1 zeigt einen Haubenofen zum Wärmebehandeln von Glühgut mit einer Mehrzahl von Sockeln gemäß einem exemplarischen Ausführungsbeispiel der Erfindung, bei dem ein Glühgas mittels eines Wärmetauschers erwärmt oder gekühlt werden kann. Die Beheizung des Wärmetauschers erfolgt anfangs durch Transportgas von einem anderen Wärmetauscher (eines abkühlenden Sockels) und anschließend mit einer elektrischen Versorgungseinheit. Die Kühlung des Wärmetauschers erfolgt anfangs durch Transportgas eines anderen Wärmetauschers (eines anheizenden Sockels) und anschließend durch eine zuschaltbare Kühleinrichtung.
• Fig. 2 bis Fig. 5 sind schematische Darstellungen von unterschiedlichen Betriebszuständen während eines Kreisprozesses zum Betreiben des Haubenofens gemäß Fig. 1.
• Fig. 6 ist eine Detailansicht eines erfindungsgemäßen Glühsockels des Haubenofens gemäß Fig. 1.
• Fig. 7 zeigt einen Haubenofen zum Wärmebehandeln von Glühgut mit einer Mehrzahl von Sockeln gemäß einem anderen exemplarischen Ausführungsbeispiel der Erfindung, bei dem ein Glühgas mittels eines Wärmetauschers erwärmt oder gekühlt werden kann. Die Beheizung des Wärmetauschers erfolgt anfangs durch Transportgas von einem anderen Wärmetauscher (eines abkühlenden Sockels) und anschließend mit einer externen Gasheizeinheit. Die Kühlung des Wärmetauschers erfolgt anfangs durch Transportgas eines anderen Wärmetauschers (eines anheizenden Sockels) und anschließend durch eine zuschaltbare Kühleinrichtung.
• Fig. 8 bis Fig. 11 sind schematische Darstellungen von unterschiedlichen Betriebszuständen während eines Kreisprozesses zum Betreiben des Haubenofens gemäß Fig. 7.
• Fig. 12 zeigt Temperatur-Zeit-Verläufe des in Fig. 1 bzw. Fig. 7 gezeigten Haubenofens, der für die verschiedenen Betriebszustände die jeweiligen Temperaturverläufe der einzelnen Sockel zeigt.
• Fig. 13 zeigt Temperatur-Zeit-Verläufe bei einem zweistufigen Betrieb eines erfindungsgemäßen Haubenofens mit zweistufiger Vorwärmphase, Heizphase, zweistufiger Vorkühlphase und Finalkühlphase, wobei drei Sockel mittels eines Transportgaspfads thermisch koppelbar sind.
• Fig. 14 zeigt eine schematische Ansicht eines Multisockelofens mit zweistufigem Wärmetausch gemäß einem exemplarischen Ausführungsbeispiel der Erfindung.
• Fig. 15 zeigt eine thermisch isolierte Schutzhaube, die mit einem Ofen gemäß einem exemplarischen Ausführungsbeispiel der Erfindung eingesetzt werden kann.
• Fig. 16 zeigt eine Draufsicht eines Haubenofens des in Fig. 6 gezeigten Typs, bei dem ein Rohrbündelwärmetauscher betriebszustandsunabhängig von einem Umwälzaggregat mit einer Ofenatmosphäre im Wesentlichen im Vollstrom beströmt wird, um zum Heizen, zum Kühlen bzw. zum Wärmetauschen jeweils eine gute Wärmekopplung zwischen Umwälzaggregat und Rohrbündelwärmetauscher zu gewährleisten.
• Fig. 17 zeigt einen Ofen gemäß einem anderen exemplarischen Ausführungsbeispiel der Erfindung, bei dem nur der Wärmetausch von abkühlendem zu aufheizendem Glühgut genützt wird und daher zusätzlich zu Schutzhauben pro Sockel jeweils eine Heizhaube vorgesehen ist. Die Finalkühlung erfolgt über den Gas-/Wasser-Kühler, wie in Fig. 1 Gleiche oder ähnliche Komponenten in unterschiedlichen Figuren sind mit gleichen Bezugsziffern versehen.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the following figures.

• Fig. 1 shows a hood furnace for heat treating annealing stock having a plurality of sockets according to an exemplary embodiment of the invention, in which a hot gas can be heated or cooled by means of a heat exchanger. The heating of the heat exchanger is initially by transport gas from another heat exchanger (a cooling base) and then with an electrical supply unit. The cooling of the heat exchanger is initially carried by transport gas of another heat exchanger (a heat-up base) and then by a switchable cooling device.
• Fig. 2 to Fig. 5 are schematic representations of different operating conditions during a cycle process for operating the hood furnace according to Fig. 1 ,
• Fig. 6 is a detailed view of a Glühsockels invention of the hood furnace according to Fig. 1 ,
• Fig. 7 shows a bell-type furnace for heat-treating annealing stock having a plurality of sockets according to another exemplary embodiment of the invention, in which a hot-gas can be heated or cooled by means of a heat exchanger. The heating of the heat exchanger is initially carried by transport gas from another heat exchanger (a cooling base) and then with an external gas heating unit. The cooling of the heat exchanger is initially carried by transport gas of another heat exchanger (a heat-up base) and then by a switchable cooling device.
• Fig. 8 to Fig. 11 are schematic representations of different operating conditions during a cycle process for operating the hood furnace according to Fig. 7 ,
• Fig. 12 shows temperature-time curves of in Fig. 1 respectively. Fig. 7 shown hood furnace, which shows the respective temperature characteristics of the individual base for the different operating conditions.
• Fig. 13 shows temperature-time courses in a two-stage operation of a hood furnace according to the invention with two-stage preheat phase, heating phase, two-stage Vorkühlphase and final cooling phase, wherein three bases are thermally coupled by means of a Transportgaspfads.
• Fig. 14 shows a schematic view of a multi-socket furnace with two-stage heat exchange according to an exemplary embodiment of the invention.
• Fig. 15 shows a thermally insulated protective hood, which can be used with a furnace according to an exemplary embodiment of the invention.
• Fig. 16 shows a plan view of a hood furnace of the in Fig. 6 shown type, in which a tube bundle heat exchanger operating state is independent of a Umwälzaggregat with a furnace atmosphere is flowed substantially in full flow to ensure for heating, for cooling or heat exchange in each case a good thermal coupling between circulating and shell and tube heat exchanger.
• Fig. 17 shows a furnace according to another exemplary embodiment of the invention, in which only the heat exchange is used by cooling to be heated Glühgut and therefore in addition to protective hoods per base each have a heating hood is provided. Final cooling is via the gas / water cooler, as in Fig. 1 The same or similar components in different figures are provided with the same reference numerals.

In the following, reference is made to Fig. 1 a hood furnace 100 according to an exemplary embodiment of the invention described.

The hood furnace 100 is designed for heat treatment of annealing material 102. This material to be annealed is arranged partly on a first base So1 of the hood furnace 100 and on another part on a second base So2 of the hood furnace 100. In the annealing 102, the in Fig. 1 is shown only schematically, it may be, for example, steel band or wire coils or the like (eg bulk material on floors) to be subjected to a heat treatment.

The hood furnace 100 has a first closable oven space 104 associated with the first pedestal So1. The first furnace chamber 104 is used for receiving and heat treating the Glühguts 102, which is fed to the first base So1 set. For heat treatment, the first furnace chamber 104 is sealed gas-tight with a first protective hood 120. The first protective hood 120 is bell-shaped and can be maneuvered by means of a crane (not shown). The first annealing gas 112, for example hydrogen, can then be introduced as a protective gas into the first furnace chamber 104 hermetically sealed by the first protective hood 120 and heated, as will be described in more detail below. A first Glühgasventilator 130 (or base fan) in the first furnace chamber 104 can be driven in rotation to circulate the annealing gas 112 in the first furnace chamber 104. As a result, the heated first annealing gas 112 can be brought into thermal active contact with the heat-treated material 102 to be heat-treated.

In the first furnace chamber 104, a first shell-and-tube heat exchanger 108 is arranged. This one is from several Windings formed by tubes, wherein transport gas 116 described in detail below is fed to a pipe inlet, flows through the pipe interior and is discharged through a pipe outlet. An outer surface of the tube bundle is in direct contact with the first annealing gas 112. The first tube bundle heat exchanger 108 serves the thermal interaction between the first annealing gas 112 and the transport gas 116, which according to one embodiment, a highly thermally conductive gas such as hydrogen or helium under high pressure of for example 10 bar. The first shell-and-tube heat exchanger 108 may be illustratively considered to be a plurality of coiled tubes wherein the transport gas may be passed through the interior of the tubes and through the wall of the tubes being thermally well-conducted, for example, metallic, in thermal interaction with that around the exterior wall of the tubes circulating first annealing gas 112 is brought. In other words, the first annealing gas 112 and the transport gas 116 are indeed fluidically decoupled or immiscible from each other, but a thermal interaction can take place by means of the first shell-and-tube heat exchanger 108 in full flow.

The first shell and tube heat exchanger 108 is disposed relative to the first annealing gas fan 130 for driving the annealing gas such that in each operating state of the furnace 100, the annealing gas driven by the first annealing gas fan 130 flows the first shell and tube heat exchanger 108. The underlying mechanism is in Fig. 16 described in more detail.

When a high pressure is used to transport the transport gas 116, for example 10 bar, the tubes of the transport gas path 118 can be provided in a small dimension, resulting in a compact construction. The pressure of the transport gas 116 may be substantially higher than the pressure of the annealing gas 112 and the Annealing gas 114 in the respective furnace chamber 104, 106 are selected (for example, a slight overpressure of between 20 mbar to 50 mbar above atmospheric pressure).

The second socket So2 has the same structure as the first socket So1. This contains a second annealing gas fan 132 for circulating second annealing gas 114, for example likewise hydrogen, in a second furnace space 106. The second furnace space 106 is hermetically sealable to the environment by means of a second protective hood 122. A second shell-and-tube heat exchanger 110 permits a thermal, but not a contacting, interaction between the second annealing gas 114 and the transport gas 116.

In the embodiment according to Fig. 1 two sockets So1, So2 are shown, however, in other embodiments, two or more sockets may be operatively coupled together.

The first furnace space 104 is bounded at the bottom by a first furnace base 170 (ie, a heat-insulated pedestal base), whereas the second furnace space 106 is bounded at the bottom by a second furnace base 172. In order to enable a fluidic interaction between the transport gas 116 circulating in a transport gas tube system and the first annealing gas 112, a supply of the transport gas 116 through the first furnace base 170 to the tube interior of the first shell-and-tube heat exchanger 108 is made possible. Similarly, supply of the transport gas 116 through the second furnace base 172 to the tube interior of the second shell and tube heat exchanger 110 is enabled. Because the transport gas 116 is introduced through the respective furnace base 170, 172 and into the respective furnace chamber 104, 106, the energy supply into the respective base So1 or So2 and the removal of energy from the respective base So1 or So2 through the furnace bases 170, 172 therethrough.

The transport gas 116 is circulated through a closed transport gas path 118, which may also be referred to as a closed transport cycle. Closed means that the transport gas 116 is enclosed in a gastight manner in the heat-resistant and pressure-resistant transport gas path 118 and is protected from leakage from the system or from mixing with other gases and from pressure equalization with the environment. Therefore, the transport gas 116 circulates through the transport gas path 118 for many cycles before the transport gas 116 can be exchanged by, for example, pumping or the like. A contact-type interaction or a mixing of the transport fluid gas 116 with the annealing gas 112 or 114 is prevented by virtue of the purely thermal coupling by means of the tube bundle heat exchangers 108, 110.

The first shell-and-tube heat exchanger 108 functions functionally as a heat-dissipating device or heat-receiving device which, apart from inlet and outlet lines, is located completely inside the first furnace chamber 104 closed by the first protective hood 120. The second shell-and-tube heat exchanger 110 likewise serves functionally as a heat-dissipating device or heat-receiving device, which-apart from inlets and outlets-is located completely inside the second furnace chamber 106 closed by the second protective hood 122. Thus, in the hood furnace 100, the heat output to the respective annealing gas 112, 114 by means disposed in the interior of the respective furnace chamber 104, 106 shell and tube heat exchangers 108, 110 (which are provided separately or independently of the protective hoods 120, 122 and covered by these) as a heat dissipation device or heat receiving device realized. Because of this heat supply to the annealing gas 112, 114 exclusively within the protective hoods 120, 122, the provision of further hoods outside the protective hoods 120, 122 is dispensable according to the invention. In other words, according to the invention, the entire thermal interaction between the annealing gas 112, 114 and heat source within the respective single protective hood 120, 122 of the respective base So1, So2 realized. This allows a compact design of the hood furnace 100 and reduces the effort with Kranspielen.

As will be described in more detail below, the closed transport gas path 118 is operatively connected to the first shell-and-tube heat exchanger 108 and to the second shell-and-tube heat exchanger 110 so that thermal energy can be transferred between the first annealing gas 112 and the second annealing gas 114 by means of the transport gas 116. For example, when the first pedestal So1 is in a cooling phase, thermal energy of the still-hot first annealing gas 112 may be transferred to the transport gas 116 by means of a heat exchange in the first shell-and-tube heat exchanger 108. The transport gas 116 heated thereby can be brought into thermal operative connection with the second annealing gas 114 via the second shell-and-tube heat exchanger 110 and thus serve for heating or preheating the second base So2. Similarly, thermal energy may alternatively be transferred from the second annealing gas 114 to the first annealing gas 112.

By the transport gas path 118 and the transport gas 116 flowing therein being strictly mechanically decoupled from the annealing gas 112 and the annealing gas 114, it is possible to keep the transport gas 116 in the transport gas path 118 under high pressure, for example 10 bar. Due to this high pressure, a high heat energy between the first annealing gas 112 and the second annealing gas 114 can be exchanged very efficiently. Furthermore, it is possible, due to this decoupling of Glühgaspfad and Transportgaspfad the transport gas 116 to choose different from the annealing gas 112, 114, so that both types of gas independently of each other on the respective function can be optimized. Also, sooting or otherwise contaminating inside the first furnace space 104 and the second furnace space 106 is inhibited, since there is no exchange of annealing gas 112, 114 therein with transport gas 116.

As part of the transport gas path 118, an electrical supply unit 124 is further provided. The electrical supply unit 124 includes a two-socket transformer 174 that is operatively coupled to an electrical supply unit 176 for providing a high voltage. Depending on the switching state of a switch 178 (secondary side), an electric current is transmitted via terminals 180 or 182 and via connection tubes 126 of the transport gas path 118 directly to the tube bundles 108 or 110. But it can also be provided per socket, a transformer to switch on the primary side at only about 1/10 of the current. The electrical supply unit 124 can also be completely deactivated. From the low-resistance pipe wall 126, the electric current is conducted to the substantially higher-resistance shell-and-tube heat exchanger 108, where the electric current is converted into heat generated by ohmic losses. Thus, the pipe wall 126 serves as a current guide, while the actual heating takes place further up the tube bundle. Thus, heating energy is transferred to the first shell and tube heat exchanger 108 and from there to the first annealing gas 112 and from the second shell and tube heat exchanger 110 to the second annealing gas 114. The electrical supply unit 124 causes the tube bundle heat exchangers 108, 110 can be heated. A first electrical insulation device 184 in the region of the first base So1 and a second electrical insulation device 186 in the region of the second base So2 ensure electrical decoupling of the pipe wall above or below these insulation elements 184, 186.

In addition, a transport gas fan 140 is provided, which is designed to convey the transport gas 116 through the transport gas path 118. As transport gas fan 140, a hot-pressure blower can be used. The transport gas path 118 further includes a switchable cooler 142 for cooling the transport gas 116 in the transport gas path 118 using a gas-water heat exchanger (alternatively, an electric cooling unit may be used at this point). At various points of the transport gas path 118, one-way valves 144 are arranged, which, for example, can be switched electrically or pneumatically in order to open or close a specific gas line path. Furthermore, multi-way valves 146 are mounted at other locations of the transport gas path 118, which are electrically or pneumatically switchable between a plurality of positions corresponding to a plurality of possible gas line paths. The switching of the valves 144, 146 and the connection or disconnection of transport gas fan 140, heating unit 124 or cooler unit 142 can also be effected by means of electrical signals. The system can either be done manually by an operator or by a control unit such as a microprocessor located in Fig. 1 is not shown and may cause an automated cycle of the operation of the hood furnace 100.

As in Fig. 1 1, a pressure vessel 148 may also selectively enclose the transport gas fan 140. The pressure vessel 148 advantageously serves as pressure protection if the transport gas path 118 can be operated at a pressure of, for example, 10 bar. Other components of the transport gas path 118 may be pressure-resistant or may also be arranged inside a pressure vessel.

Fig. 1 further shows a control unit 166 configured to control and switch the individual components of the furnace 100, as shown in FIG Fig. 1 is indicated schematically by arrows.

In addition, on Fig. 2 to Fig. 5 Reference is made, in which different operating states of the hood furnace 100 are shown, which are adjustable by appropriate control (with the control unit 166) of the position of the fluidic valves 144, 146 and the electric switch 178.

In an in Fig. 2 shown first operating state I, the transport gas fan 140 is thermally coupled to the second annealing gas 114, so that the transport gas 116 takes the second annealing gas 114 heat and the first annealing gas 112 feeds. In the operating state I, the first furnace chamber 104 is thus preheated and the second furnace chamber 106 is precooled by the transport gas 116 transferring thermal energy from the first annealing gas 112 to the second annealing gas 114. As a result, the charge (the material to be annealed) of the base So1 is heated and the charge (the annealing material) of the second base So2 is cooled.

Fig. 3 shows a second operating state II of the hood furnace 100, which follows the first operating state I. In the second operating state II, the tube bundle 108 with the electrical supply unit 124 electrically heats the first oven space 104 by closing a corresponding electrical path. In a separate fluidic path, the transport gas fan 140 supplies the transport gas 116 to the now connected cooler 142 for cooling the second annealing gas 114. The now cooled transport gas 116 is thermally coupled to the second annealing gas 114 to cool the second furnace space 106. According to Fig. 3 Thus, the charge (the Glühgut) of the first base So1 is further heated, whereas the charge (the annealing material) of the second base So2 is further cooled.

After the second operating state II, the now heat-treated and meanwhile cooled charge of annealed stock 102 is removed from the second base So2. For this purpose, a crane, the second guard 122, then remove the arranged in the second base So2 Glühgut 102 and introduce a new batch of Glühgut 102 in the second base So2.

This is followed by a third operating state III, which in Fig. 4 is shown. In this third operating state III, the transport fluid fan 140 thermally couples the transport fluid 116 with the first annealing gas 112, so that the transport gas 116 removes heat from the first annealing gas 112 and supplies it to the second annealing gas 114. As a result, the second furnace chamber 104 is preheated and the first furnace chamber 106 is pre-cooled.

After this third operating state III, a subsequent fourth operating state IV is activated, which in Fig. 5 is shown. In the fourth operating state IV, the tube bundle 110 with the electrical supply unit 124 electrically heats only the second oven chamber 106. In a separate fluidic path, the transport fluid fan 140 supplies the transport gas 116 to the now switched on cooler 142 for cooling. The cooled transport gas 116 is thermally coupled to the first annealing gas 112 to further cool the first furnace space 104. Thus, the charge (the material to be annealed) of the first base So1 is now cooled further and the charge (the annealing material) of the second base So2 is further electrically heated.

After the fourth operating state IV, the now heat-treated and now cooled charge of Glühgut 102 is removed from the first base So1. For this purpose, a crane can remove the first protective hood 120, then remove the annealing stock 102 arranged in the first base So1 and introduce a new batch of annealed stock 102 into the first base So1.

Now, the cycle of operating states I to IV can start anew, ie the hood furnace 100 is next again according to Fig. 2 operated.

Fig. 6 shows an enlarged view of a portion of the first base So1 of the hood furnace, showing the arrangement of the tube bundle heat exchanger 108 in full flow with inlet and outlet in detail. The thermal insulation of the protective hood 120 is identified by the reference numeral 600.

The first annealing gas fan 130 is a radial fan whose impeller 602 is driven by a motor 604. Impeller 602 is enclosed by vanes 608 having vanes. The annealing material 102 resting on the glow base, which is indicated only schematically, is covered by the protective hood 120, which is supported via an annular flange 612, which ensures a gas-tight closure of the protective hood 120 via a circumferential seal 614.

Fig. 7 shows a bell annealing furnace 100 according to another exemplary embodiment of the invention.

In the hood furnace 100 according to Fig. 7 Instead of the electrically heated furnace-internal heat exchange bundles 108/110 with electrical supply unit 124, an oven-external gas heating unit 700 is provided. As an oven-external heating unit alternatively also an electrical heating unit can be used. The gas heating unit 700 is associated with a separate heating fan 704 which transports transport gas 116 heated by the gas heating unit 700 through a piping system. According to Fig. 7 For example, transport gas 116 heated by the gas heating unit 700 is conveyed through the tube bundle heat exchangers 108, 110.

Furthermore, a control unit 702 is provided, which is formed via various control lines 720 for switching the various valves 144, 146 and for switching on or off the radiator 142, the gas heating unit 700 or the fans 140, 704. The fan 140 may be formed as a cold-pressure fan, whereas the fan 704 is a hot-pressure fan.

The gas heating unit 700 functions as a heater and is formed as a gas-heated heat exchanger for transferring thermal energy to the transport gas 116.

The area below the furnace bases 170, 172 in Fig. 7 may be wholly or partially mounted inside a high-pressure vessel to provide protection against the high pressure in the transport gas system 118.

Fig. 8 to Fig. 11 show four operating states of the hood furnace 100 according to Fig. 7 which are functionally the operating states I to IV according to Fig. 2 to Fig. 5 correspond.

According to the operating state I in Fig. 8 For example, the radiator 142 is disconnected from the rest of the system. The gas heating unit 700 is turned off. Heat is transferred from the second annealing gas 114 of the second header So2 to the first annealing gas 112 in the first header So1.

According to operating status II in Fig. 9 For example, the first base So1 is further heated by the gas heating unit 700 which is now switched on, while the cooler 142 is now activated in a separate other gas path and the second annealing gas 114 is actively further cooled in the second base So2.

After expiration of the operating state II, the annealing material 102 can be removed from the second base So2 and replaced by a new, heat-treatable batch of annealed material 102.

Fig. 10 shows the third operating state III, in which thermal energy is now transferred from the first annealing gas 112 in the first base So1 to the second annealing gas 114 in the second base So2. The radiator 142 and the gas heating unit 700 are turned off in this state.

Operating state III is then replaced by operating state IV, which in Fig. 11 is shown. In accordance with this operating state, the cooler 142 is activated and actively cools the first base So1 further. In In a separate fluid path, the second base So2 is actively heated further by means of the gas heating unit 700.

After carrying out the procedure in accordance with the fourth operating state IV, the annealing stock 102 can be removed from the first base So1 and replaced by a new batch of annealed stock 102.

In the following, reference will be made to Fig. 12 a first diagram 1200 and a second diagram 1250 are described. The first graph 1200 has an abscissa 1202 along which the time is plotted while performing the operating conditions I to IV. Along an ordinate 1204, the temperature of the respective annealing gas or the Glühguts is plotted while performing the operating states I to IV. The abscissa 1202 and the ordinate 1204 are also selected accordingly in the second diagram 1250.

The first graph 1200 relates to a temperature profile of the first annealing gas 112 and the Glühguts the first base So1 during the passage through the individual operating states I to IV, whereas the second graph 1250 on a temperature profile of the second annealing gas 114 and the Glühguts the second Base So2 during operating states I to IV according to Fig. 1 or Fig. 7 refers. In the first operating state I, thermal energy is transferred from the second annealing gas 114 in base So2 to the first annealing gas 112 in base So1 (first heat exchange WT1 with energy transfer E). In the second operating state II, the first base So1 is actively heated further with annealing material (H), whereas the second base So2 is actively cooled further actively with annealing material (K). In the following third operating state III, thermal energy is now transferred from the first annealing gas 112 or the annealed material in the first base So1 to the second annealing gas 114 or the annealed material in the second base So2 (second heat exchange WT2 with energy transfer E). By doing fourth operating state IV, the first base So1 is further actively cooled with Glühgut, whereas the second base So2 is actively heated with annealing material.

Thus shows Fig. 12 the temperature profile in a two-socket operation according to Fig. 1 or according to Fig. 7 , By such a single-stage heat exchange (ie, a one-stage preheating a base with Glühgut by supplying Glühgaswärme the other socket before active reheating by means of a heating unit), the energy consumption can be reduced to about 60%. Such an embodiment is simple and reduces the energy by 40% due to the reuse of waste heat to be cooled each base with Glühgut the energy.

Fig. 13 FIG. 12 shows a first diagram 1300, a second diagram 1320, a third diagram 1340 and a fourth diagram 1360 of a two-stage heat exchange system in which, unlike in FIG Fig. 1 and Fig. 7 two pedestals, but three pedestals are provided in a hood furnace. In such a two-stage heat exchange, a two-stage preheating of a base with Glühgut by supplying Glühgaswärme the other two sockets with Glühgut (successively, ie two stages) before the active reheating by means of a heating unit.

• In einem ersten Betriebszustand I wird ein dritter Sockel So3 vorgekühlt und überträgt mittels des Transportgases thermische Energie von dem dritten Glühgas auf das erste Glühgas, um einen Sockel So1 vorzuwärmen. Gleichzeitig wird ein von dem ersten und dem dritten Sockel in diesem Betriebszustand getrennter zweiter Sockel So2 mittels einer Heizeinrichtung auf eine Endtemperatur geheizt.

In this heat exchange system, six different operating states are distinguishable:

• In a first operating state I, a third base So3 is pre-cooled and transmits by means of the transport gas thermal energy from the third annealing gas to the first annealing gas to preheat a base So1. At the same time, a second pedestal So2 separated from the first and third pedestals in this operating state is heated to a final temperature by means of a heater.

In a subsequent second operating state II, the base So3 is actively cooled by means of a cooler, while the base now to be pre-cooled transfers thermal energy from its second annealing gas to the first annealing gas of the first base So1. As a result, the first base So1 is further preheated.

In a third operating state III, the third base So3 is reheated by transferring thermal energy from the second base So2 to the third base So3 by means of the transport gas. This preheats the third base So3. Since the second base So2 transfers thermal energy of its second annealing gas to the third annealing gas of the third base So3, its energy decreases in the third operating state III. The first base So1 is now isolated from the other bases So2 and So3 and is heated by means of a heater to a final temperature.

In a subsequent fourth operating state IV, the first base So1 is pre-cooled by transferring thermal energy from the first annealing gas to the third annealing gas of the base So3. As a result, the third base So3 is further preheated. The second base So2 is separated in a fourth operating state from the other two sockets So1, So3 and is actively cooled further with a cooler, in order then to reach its lower end temperature at the end of the fourth operating mode IV.

In a subsequent fifth operating state V, the third pedestal So3 is activated and connected to the heating unit separately from the other pedestals So1, So2 to be brought to the final temperature. The further base So1 to be cooled transfers thermal energy from its annealing gas to the second annealing gas of the second base So2. The latter is thus subjected to a first preheating phase.

In a subsequent sixth operating mode VI, thermal energy from the third base So3, which is now pre-cooled to be transferred to the second socket So2. As a result, the second base So2 is subjected to a second preheating and the third base So3 is pre-cooled. The first base So1 is in this operating condition in isolation from sockets So2, So3 and is cooled by a cooler to a final temperature. After completion of operating state VI, the cycle begins again with the first operating state I.

Fig. 13 thus refers to a two-stage heat exchange in a three-socket operation. Energy consumption can be reduced to 40%. The construction of a corresponding furnace according to the invention is still simple, and it can still be achieved a high level of energy gain of about 60%.

Fig. 14 FIG. 11 shows a schematic view of a furnace 1600 having generally n sockets according to another exemplary embodiment. There, a first socket So1 1602, a second socket So2 1604 and an n-th socket SoN 1606 are shown schematically. The architecture according to Fig. 16 can be applied to any number of sockets. A plurality of one-way valves 144 are also in Fig. 14 shown. Further, a cooling unit 142 and an external heating unit 700 (in this case, a gas heating unit, which is alternatively possible as an electric resistance heater) are shown. If the shell-and-tube heat exchanger is used directly, ie internally as electrical resistance heating, one electrical supply unit per socket is provided (1241, 1242, ..., 124n). For a two-stage heat exchange, one fan unit each is provided for WT1 or WT2.

Fig. 15 shows a bell-shaped protective hood 1700, as shown for example in Fig. 1 with reference numerals 120, 122. The protective hood 1700 has a continuous inner housing made of a heat-resistant material 1702 and a heat insulation 1704 outside to preserve the respective base from heat loss through the protective hood 1700 therethrough. The configuration shown is advantageously used for a hood furnace. For a chamber furnace on the other hand, it may be advantageous to combine an inner wall made of a thermally insulating material with a steel outer wall, that is to say clearly replace reference numerals 1702 and 1704.

Fig. 16 shows a plan view of a hood furnace of the in Fig. 6 of the type shown, in which a shell-and-tube heat exchanger 108 is directed (and preferably substantially completely) by means of a hot gas fan 130 and is supplied with heated annealing gas. Thus, a good thermal coupling between the Glühgasventilator 130 and the tube bundle heat exchanger 108 can be ensured for all operating conditions of the hood furnace, ie for heating a base, for cooling a base or heat exchange between sockets.

More specifically, an impeller 602 of the Glühgasventilators 130 is driven in rotation, see reference numeral 1642. Thereby, the annealing gas is circulated by the Glühgasventilator 130. The annealing gas therefore moves outward under the influence of the stationary vanes 1640 of a nozzle. As a result, the annealing gas reaches specifically in thermal interaction with the tube bundle heat exchanger 108 and on to the charge (Glühgut). The tube bundle heat exchanger 108 is therefore in full flow.

In Fig. 17 For example, an oven 1800 according to yet another exemplary embodiment of the invention is shown. The 1800 oven is similar to Fig. 1 formed, but has at its first base in addition to the first guard 120 a this enclosing removable first heating hood 1802. Accordingly, the second guard 122 of the second base of a second heating hood 1804 is covered. The first heating burners 1806 are in a gap 1810 between the first heating hood 120 and the first Protective cover 1802 provided for heating the protective gas within the protective hood. Accordingly, in the second furnace room 106, the second heating burners 1808 for heating a gap 1812 between the second heating hood 122 and the second protective hood 1804 are provided. It is possible to provide electrical resistance heating elements 1806, 1808 instead of the heating burners 1808. The electrical supply unit 124 according to Fig. 1 is in Fig. 17 omitted. The switchable gas-water heat exchanger 142 is maintained.

According to the embodiment of Fig. 17 Thus, the main heating of the first annealing gas 112 and the second annealing gas 114 by the thermal interaction between the heated gas in the gap 1810 and the first annealing gas 112 and the heated gas in the space 1812 and the second annealing gas 114 (or an electrical resistance heater) accomplished. The transport fluid path 118 is used in this embodiment for the thermal compensation between the first annealing gas 112 and the second annealing gas 114 in order to pre-cool or preheat and thus save energy. Further, final cooling may be accomplished by a cooling unit 142 associated with the transport gas path 118.

It should also be noted that in the embodiment according to Fig. 17 Also, a cooling hood can be placed.

In addition, it should be noted that "having" does not exclude other elements or steps, and "a" or "an" does not exclude a multitude. It should also be appreciated that features or steps described with reference to any of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limiting.

Claims (15)

1. Furnace (100) for heat treating of annealing good (102), wherein the furnace (100) comprises:

   a closable first furnace chamber (104) which is formed for receiving and for heat treating of annealing good (102) by thermal interacting of the annealing good (102) with heatable or coolable first annealing gas (112) in the first furnace chamber (104);

   a first heat exchanger (108) arranged in the first furnace chamber (104), which is formed for thermal exchange between the first annealing gas (112) and a transport fluid (116), wherein the first heat exchanger (108) is arranged inside a housing section (120) of the first furnace chamber (104), which housing section (120) encloses the first annealing gas (112) in the interior of the first furnace chamber (104) and which housing section (120) is in direct contact with the first annealing gas (112);

   a closable second furnace chamber (106) which is formed for receiving and for heat treating of annealing good (102) by thermal interacting of the annealing good (102) with heatable or coolable second annealing gas in the second furnace chamber (106);

   a second heat exchanger (110) arranged in the second furnace chamber (106), which is formed for thermal exchange between the second annealing gas (114) and the transport fluid (116), wherein the second heat exchanger (110) is arranged inside a housing section (122) of the second furnace chamber (106),

   which housing section (122) encloses the second annealing gas (114) in the interior of the second furnace chamber (106);

   a closed transport fluid path (118) which is effectively connected with the first heat exchanger (108) and with the second heat exchanger (110) in such a way that thermal energy is contactless transferable by the transport fluid (116) between the first annealing gas (112) and the second annealing gas (114).
2. Furnace (100) according to claim 1, wherein the furnace (100) is formed as a furnace being operatable in batches.
3. Furnace (100) according to claim 1 or 2, wherein the first furnace chamber (104) is closable by a removable first protecting cover (120) as the housing section (120) of the first furnace chamber (104) and the second furnace chamber (106) is closable by a removable second protecting cover (122) as the housing section (122) of the second furnace chamber (106), and wherein the first protecting cover (120) is the outermost cover of the first furnace chamber (104) and the second protecting cover (122) is the outermost cover of the second furnace chamber (106), and/or
   wherein the housing section (122) of the second furnace chamber (106) is in direct contact with the second annealing gas (114).
4. Furnace (100) according to claim 3, wherein the first protecting cover (120, 1700) and the second protecting cover (122, 1700) each comprises a heat resistant internal housing (1702) and an insulating casing (1704) from a heat insulating material.
5. Furnace (100) according to one of the claims 1 to 4, wherein an external heating unit (700) for direct heating of the transport fluid (116) to the first heat exchanger (108) or to the second heat exchanger (110) is arranged in such a way that the first furnace chamber (104) is heatable by thermal transfer of heating energy to the first annealing gas (112) and/or the second furnace chamber (106) is heatable by thermal transfer of heating energy to the second annealing gas (114), wherein the external heating unit (700) may be operated by gas, oil or pellets or comprises an electric resistance heater.
6. Furnace (100) according to claim 5, wherein the electric supply unit (124) of the heating unit supplies the first heat exchanger (108) or the second heat exchanger (110) as an electric resistance heater and thereby internally and directly with electric energy.
7. Furnace (1800) according to claim 3, wherein the first furnace chamber (104) is closable with a removable and heatable first heating cover (1802), which encloses the first protecting cover (120), and wherein the second furnace chamber (106) is closable with a removable and heatable second heating cover (1804), which encloses the second protecting cover (122).
8. Furnace (100) according to one of the claims 1 to 7, wherein the first heat exchanger (108) and/or the second heat exchanger (110) is formed as a tube bundle heat exchanger made of tubes bended to a bundle, wherein the interior of the tube is part of a transport fluid path (118) and is through flowable by a transport fluid (116) and the exterior of the tube is brought in direct contact with the respective annealing gas (112, 114), and/or
   wherein the first furnace chamber (104) comprises a first annealing gas drive (130) and the second furnace chamber (106) comprises a second annealing gas drive (132), wherein the respective annealing gas drive (130, 132) is arranged to point the respective annealing gas (112, 114) at the respective heat exchanger (108, 110) and at the respective annealing good (102).
9. Furnace (100) according to one of the claims 1 to 8, further comprising:

   a closable third furnace chamber which is formed for receiving and for heat treating of annealing good (102) by thermal interacting of the annealing good (102) with heatable third annealing gas in the third furnace chamber;

   a third heat exchanger arranged in the third furnace chamber, which is formed for thermal exchange between the third annealing gas and the transport fluid (116), wherein the third heat exchanger is arranged inside a housing section of the third furnace chamber, which housing section encloses the third annealing gas in the interior of the third furnace chamber;

   wherein the closed transport fluid path (118) is also effectively connected with the third heat exchanger in such a way that thermal energy is transferable by the transport fluid between on the one hand the third annealing gas and one the other hand the first annealing gas (112) and/or the second annealing gas (114).
10. Furnace (700) according to one of the claims 1 to 9, comprising a control unit (702) which is arranged to control the transport fluid path (118) in such a way that by thermal exchange between the transport fluid (116) and the first annealing gas (112) and the second annealing gas (114) selectively a respective one of the first furnace chamber (104) and the second furnace chamber (106) is operatable in a pre heating mode, a heating mode or a cooling mode, and/or wherein the transport fluid path (118) comprises a transport fluid drive (140) for driving the transport fluid (116) through the transport fluid path (118), and/or wherein the transport fluid path (118) comprises a connectable cooler (142) for cooling the transport fluid (116) in the transport fluid path (118).
11. Furnace (100) according to claim 10, wherein the transport fluid path (118) comprises a plurality of valves (144, 146) which are switchable in such a way that the furnace (100) is selectively operated in one of the following operating modes:

    a first operating mode in which the transport fluid drive thermally couples the transport fluid (116) with the second annealing gas (114) such that the transport fluid (116) removes heat from the second annealing gas (114), and supplies it to the first annealing gas (112) for heating the first furnace chamber (104) and for cooling the second furnace chamber (106);

    a subsequent second operating mode in which a heating unit (124, 700) further heats the first furnace chamber (104) and in which in a therefrom separated path the transport fluid drive (140) supplies the transport fluid (116) to the connected cooler (142) for cooling, and thermally couples the cooled transport fluid (116) with the second annealing gas (114) for further cooling of the second furnace chamber (106);

    a subsequent third operating mode in which the transport fluid drive (140) thermally couples the transport fluid (116) with the first annealing gas (112) such that the transport fluid (116) removes heat from the first annealing gas (112), and supplies it to the second annealing gas (114) for heating the second furnace chamber (106) and for cooling the first furnace chamber (104);

    a subsequent fourth operating mode in which the heating unit (124, 700) heats the second furnace chamber (106) and in which in a therefrom separated path the transport fluid drive (140) supplies the transport fluid (116) to the connected cooler (142) for cooling, and thermally couples the cooled transport fluid (116) with the first annealing gas (114) for cooling the first furnace chamber (104).
12. Furnace (100) according to one of the claims 1 to 11, comprising a means for pressure stabilizing of the transport fluid path (118), which encloses in a pressure sealed way at least a part of the transport fluid path (118).
13. Furnace (100) according to one of the claims 1 to 12, wherein the first heat exchanger (108) is arranged relatively to a first annealing gas ventilator (130) for driving the first annealing gas and/or the second heat exchanger (110) is arranged relatively to a second annealing gas ventilator (132) for driving the second annealing gas in such a way that in every operating mode of the furnace (100) the first annealing gas driven by the first annealing gas ventilator (130), blows to the first heat exchanger (108) and/or that in every operating mode of the furnace (100) the second annealing gas driven by the second annealing gas ventilator (132), blows to the second heat exchanger (110).
14. Furnace (100) according to one of the claims 1 to 13, which is configured in such a way that the first annealing gas (112) and the second annealing gas (114), remains contactless towards the transport fluid (116).
15. Method for heat treating of annealing good in a furnace (100), wherein the method comprises:

    receiving and heat treating of annealing good (102) in a closable first furnace chamber (104) by thermal interacting of the annealing good (102) with heatable and coolable, respectively, first annealing gas (112) in the first furnace chamber (104);

    causing a thermal exchange between the first annealing gas (112) and a transport fluid (116) by a first heat exchanger (108) arranged in the first furnace chamber (104), wherein the first heat exchanger (108) is arranged inside a housing section (120) of the first furnace chamber (104), which housing section (120) encloses the first annealing gas (112) in the interior of the first furnace chamber (104) and which housing section (120) is in direct contact with the first annealing gas (112);

    receiving and heat treating of annealing good (102) in a closable second furnace chamber (106) by thermal interacting of the annealing good (102) with heatable and coolable, respectively, second annealing gas (114) in the second furnace chamber (106);

    causing a thermal exchange between the second annealing gas (114) and the transport fluid (116) by a second heat exchanger (110) arranged in the second furnace chamber (106), wherein the second heat exchanger (110) is arranged inside a housing section (122) of the second furnace chamber (106), which housing section (122) encloses the second annealing gas (114) in the interior of the second furnace chamber (106);

    controlling a closed transport fluid path which is effectively connected with the first heat exchanger (108) and with the second heat exchanger (110) in such a way that by the transport fluid (116) thermal energy is transferable between the first annealing gas (112) and the second annealing gas (114).

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