Heating system with high temperature heat storage

Abstract

A heating system comprises a high-temperature heat accumulator (1) and a furnace (2). The heating system comprises a piping system (8) for heating a material (6) located in the furnace (2), via which the high-temperature heat accumulator (1) and the furnace (2) are fluidically connected to one another. As a result, a gas (9) can be conducted in the piping system (8) from the high-temperature heat accumulator (1) to the furnace (2) and back in a closed circuit. The gas (9) is inert with respect to contact surfaces of the storage material (4) located in the high-temperature heat accumulator (1) and with respect to the material (6) located in the furnace (2). The heating system further comprises an inductive heating device (3), by means of which thermal energy can be supplied to the high-temperature heat accumulator (1).

Description

field of technology

[0001] The present invention is based on a heating system comprising a high-temperature heat storage device. State of the art

[0002] Such a heating system is advertised, for example, by the company Carbon-Clean Technologies GmbH, Widdersdorfer Str. 217a, 50825 Cologne, Germany.

[0003] DE 10 2008 044 280 A1 discloses a continuous-flow heater for the household sector. A medium to be heated is passed through a continuous-flow heater containing a heating element around which the medium flows or through. The medium can be a gas or a liquid. The heating element is made of an electrically conductive material and is indirectly heated inductively via a coil, allowing it to transfer its heat to the medium. Summary of the invention

[0004] The production of iron and steel requires large amounts of heat at high temperatures. For example, in a conventional hot strip mill, slabs are heated in a furnace to temperatures of 1000°C and above before being rolled in a roughing mill and then in a finishing mill. In heavy plate mills, the slabs are also preheated to temperatures of 1000°C and above. The same applies to other rolling mills. The furnaces required for heating are usually powered by natural gas. The natural gas is burned with air, producing carbon dioxide and water. The resulting exhaust gas is released into the environment via a stack.

[0005] For environmental protection reasons, particularly to reduce or avoid carbon dioxide emissions, there are considerations to add hydrogen to natural gas or to replace it entirely with hydrogen. Adding hydrogen to natural gas or replacing natural gas with hydrogen requires at least an inspection of the pipelines and burners, and often also a conversion. This approach can only lead to a reduction in carbon dioxide emissions if the hydrogen is produced in an environmentally friendly manner.By considering the typical efficiencies of electrolysis plants, the energy quantities subsequently unrecoverable for compressing and transporting the hydrogen, the storage losses of hydrogen, and the efficiency of hydrogen combustion, it is easy to determine that even theoretically, the resulting overall efficiency is well below 40%. A realistic overall efficiency of approximately 30% is therefore uneconomical to operate such a furnace with hydrogen.

[0006] It is also known to inductively heat slabs and other rolled stock. Induction heating is more efficient than is possible using hydrogen. However, induction heating also has significant disadvantages. Firstly, the required peak electrical power is very high. In practice, it is in the double-digit megawatt range. This can be particularly disadvantageous if an overall plant, into which the furnace is integrated, temporarily requires high electrical power for other reasons, for example, for rolling a rolled stock. The associated induction heating system itself is expensive, complex to install, and not easily replaced in the event of a failure. Furthermore, there are significant disadvantages from a metallurgical point of view.Firstly, induction heating only affects small areas of the rolled stock, meaning that the heating is uneven and the rolled stock is not heated throughout. Furthermore, it heats up very quickly. This is a disadvantage because although the rolled stock is heated, a significant amount of time is required for the alloying elements and precipitates in the rolled stock to dissolve. Many steel alloys require several hours for the alloying elements and precipitates in the rolled stock to dissolve, during which time they must be kept at temperature before they can be rolled. An induction furnace is unsuitable for this. To reduce the cost of purchasing electrical energy, it is also necessary to buffer electrical energy in a battery storage system so that a lot of energy does not have to be purchased at times when electrical prices are high.Due to the amount of energy required, the battery storage system would have to be able to store and provide a considerable amount of energy, for example 100 MWh or more.

[0007] The object of the present invention is to provide a heating system by means of which the disadvantages of the prior art can be avoided.

[0008] The object is achieved by a heating system having the features of claim 1. Advantageous embodiments of the heating system are the subject of dependent claims 2 to 14.

[0009] According to the invention, a heating system of the type mentioned at the outset is designed in that that the heating system also comprises a furnace in addition to the high-temperature heat storage device, that the heating system for heating a material located in the furnace comprises a first line system via which the high-temperature heat storage device and the furnace are fluidically connected to one another, so that in the first line system a first gas can be guided from the high-temperature heat storage device to the furnace and back in a first closed circuit, that the first gas is inert with respect to contact surfaces of the storage material located in the high-temperature heat storage device and with respect to the material located in the furnace, and that the heating system comprises an inductive heating device by means of which heat energy can be supplied to the high-temperature heat storage device.

[0010] In particular, the use of a closed circuit makes it possible to select the first gas as needed, and in particular, to select it so that it is inert both in the high-temperature heat storage unit and for the material in the furnace. Furthermore, the use of a high-temperature heat storage unit with suitable insulation enables significantly more compact, efficient, and also more cost-effective energy storage than would be possible with a battery storage system. An inductive heating device, in turn, enables efficient, cost-effective heating of the high-temperature heat storage unit. Heating can be decoupled from the thermal energy drawn from the high-temperature heat storage unit, so that power peaks can be completely avoided or at least largely reduced.The arrangement and design of the inductive heating device can still be determined independently of the conditions of the furnace - with the exception of the required heating power.

[0011] A high-temperature heat storage device within the meaning of the present invention is a heat storage device in which the storage material in the heat storage device can be heated to temperatures of 1000 °C and more, for example to temperatures of 1200° or more or even 1400° or more or 1500° or more.

[0012] In the simplest case, the inductive heating device is located within the high-temperature heat storage unit itself. This design is particularly simple and compact.

[0013] However, it is alternatively possible and in some cases even preferable, that the heating system for charging the high-temperature heat accumulator comprises a second line system via which the high-temperature heat accumulator and the inductive heating device are fluidically connected to one another, so that in the second line system a second gas can be guided from the inductive heating device to the high-temperature heat accumulator and back in a second closed circuit, wherein the second gas is inert with respect to the contact surfaces of the storage material located in the high-temperature heat accumulator and an inductively heated radiator located in the heating device.

[0014] This design enables, in particular, efficient loading of the high-temperature heat storage unit.

[0015] It is possible for the first and second piping systems to be separate from each other, thus forming two independent circuits. In many cases, however, it is equally possible, and also simpler and more flexible, for the first and second piping systems to have common sections. This can reduce the piping effort. Since both the first and second gases flow in the common sections, in this case the second gas is identical to the first gas. The distinction is purely linguistic.

[0016] For example, in this case, it is possible for the first and / or second line system to have elements that can be adjusted by a control device, so that the control device can adjust the extent to which the first gas extracted from the high-temperature heat storage device and / or the second gas heated by the inductive heating device are supplied to the furnace. This allows for a significant degree of peak shaving, i.e., the avoidance of load peaks on the inductive heating device, even with a relatively small high-temperature heat storage device.

[0017] It may also be possible for the control device to use the adjustable elements to adjust the extent to which the second gas heated by the inductive heating device is fed to the high-temperature heat storage device and / or the furnace. This allows for very flexible use of the inductive heating device. In particular, one and the same inductive heating device can provide heat for both the furnace and the high-temperature heat storage device.

[0018] The adjustable elements can be, for example, compressors or fans, whose drives can be controlled by the control system. If no gas is to flow through certain sections of the piping system temporarily, flaps or similar closure devices can also be closed if necessary.

[0019] The high-temperature heat storage device is preferably designed as a stratified storage device. In this case, the first gas is extracted from the high-temperature heat storage device in an upper region to heat the material in the furnace and, after flowing through the furnace, is fed back in a lower region. If charging is carried out using the second gas, the second gas is similarly extracted from the high-temperature heat storage device in the lower region for charging and, after flowing through the inductive heating device, is fed back in the upper region. By using a stratified storage device, the temperature of the first gas extracted from the high-temperature heat storage device can be maintained at a high level for a very long time.

[0020] The storage material in the high-temperature heat storage device preferably consists of spherical storage elements. Such storage elements offer a relatively high filling level relative to the total volume of the high-temperature heat storage device, while the spaces and gaps between the storage elements nevertheless form a low-resistance path for the first and / or second gas.

[0021] The storage elements preferably have an outer shell and an inner core. In this case, it is possible for a phase transition temperature of the inner cores to be below a melting temperature of the outer shells. As a result, the phase transition, for example during melting or solidification of the cores, can increase the heat capacity of the high-temperature heat storage device for the same volume. Particularly preferably, the phase transition temperature of the inner cores in this case is at a desired upper operating temperature of the high-temperature heat storage device or slightly below it. Alternatively or additionally, the inner cores can be made of the same material as the material in the furnace. This applies in particular if the material in the furnace is to be heated but not melted.As an alternative to the phase transformation of the inner cores and the matching of the material of the inner cores to the material of the material in the furnace, it is possible for the inner cores to consist of a mixture of several substances, with the proportions of the substances varying with the temperature of the high-temperature heat storage. In this case, a large amount of energy can be absorbed or released through the reaction enthalpy.

[0022] The storage material, unless divided into a shell and core, is preferably a ceramic. Ceramics can be heated to very high temperatures without cracking.

[0023] Preferably, the furnace is designed such that the material contained in the furnace is a rolled metal stock, in particular steel. Such furnaces require large amounts of thermal energy at a high temperature level. This is where the full benefits of using the high-temperature heat storage system, including the closed first circuit and the use of an inert first gas, become apparent. The rolled stock can, in particular, be formed as a flat, elongated rolled stock (slab or pre-strip).

[0024] In many cases, it is advantageous if the first gas consists of water vapor and / or carbon dioxide. This is particularly advantageous in conjunction with a furnace for heating rolled stock, because in this case the rolled stock is chemically heated using a medium that differs little, or not at all, from the medium used to heat the rolled stock using conventional natural gas burners. It can therefore be safely assumed that no unexpected side effects will occur. Furthermore, the burners used in the prior art for burning natural gas can be used as outlet nozzles for the first gas without further modification. Short description of the drawings

[0025] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following description of an embodiment, which is explained in more detail in conjunction with the drawings. FIG 1a heating system, FIG 2a plan view of a furnace, FIG 3a section through the furnace of FIG 2 along a line III-III in FIG 2 , FIG 4 a section through the furnace of FIG 2 along a line IV-IV in FIG 2 , FIG 5 a high-temperature heat storage, FIG 6 to 8 heating systems and FIG 9 to 11 sections through storage elements. Description of the embodiments

[0026] According to FIG 1 A heating system comprises a high-temperature heat storage unit 1, a furnace 2 and an inductive heating device 3.

[0027] The high-temperature heat storage device 1 contains a storage material 4. The storage material 4 can be a liquid storage medium in individual cases. However, the storage material 4 is generally in a solid state. For example, the storage material 4 can be as shown in FIG 1 consist of spherical storage elements 5. The storage material 4 can be heated in the high-temperature heat storage device 1 to high temperatures T of 1000 °C and more, even to temperatures T of 1200 °C and more, or 1400 °C and more, or 1500 °C and more. Possible configurations of the storage material 4 will be explained later.

[0028] A product 6 is located in the furnace 2. The furnace 2 is thus designed to accommodate the corresponding product 6. The product 6 can, for example, be a rolled product made of metal, in particular steel. In particular, the product 6 can be formed as shown in the FIG 2 bis 4 a flat, elongated rolled product. Specifically, in the case of a flat, elongated rolled product, the product 6 is conveyed in the furnace 2 transversely to a longitudinal direction of the product 6. The conveying direction is shown in the FIG 2 and 3 indicated by an arrow 7.

[0029] To heat the material 6 located in the furnace 2, the heating system comprises a first piping system 8. The high-temperature heat storage unit 1 and the furnace 2 are fluidly connected via the first piping system 8. A first gas 9 can be conducted from the high-temperature heat storage unit 1 to the furnace 2 and back in the first piping system 8. The first piping system 8 thus forms a first closed circuit for the first gas 9.

[0030] The first gas 9 flows in the high-temperature heat storage unit 1 along contact surfaces of the storage material 4 located in the high-temperature heat storage unit 1. Likewise, the first gas 9 flows in the furnace 2 along the material 6 located in the furnace 2. For this reason, the first gas 9 is selected such that it is inert with respect to the contact surfaces of the storage material 4 and with respect to the material 6, i.e. it does not react chemically. In many cases - particularly when the material 6 is a rolled stock - the first gas 9 can consist of water vapor (H 2 O) and / or carbon dioxide (CO 2 ). Especially for heating a rolled stock, the first gas 9 should be free of nitrogen or at least contain as little nitrogen as possible (maximum 25 percent by volume).

[0031] Preferably, the high-temperature heat storage device 1 is designed as shown in FIG 5 designed as a stratified storage tank. The storage material 4 located in the high-temperature heat storage unit 1 therefore has a temperature T1 in a lower region 10 and a temperature T2 in an upper region 11, wherein temperature T2 is greater than temperature T1. Between the lower and upper regions 10, 11, the storage material 4 has temperatures T that gradually rise from bottom to top from temperature T1 to temperature T2. To heat the material 6 located in the furnace 2, the first gas 9 is taken from the upper region 11 and fed to the furnace 2 via the first line system 8. There, the first gas 9 flows through the furnace 2 and thus heats the material 6 located in the furnace 2.

[0032] The first gas 9 is thereby cooled. After flowing through the furnace 2, the first gas 9 is fed back to the high-temperature heat storage unit 1 via the first pipe system 8, specifically in the lower area 10.

[0033] By means of the inductive heating device 3, heat energy can be supplied to the high-temperature heat storage device 1. In the case of the design of FIG 1 the inductive heating device is arranged in the high-temperature heat storage unit 1 itself.

[0034] FIG 6 shows an alternative design of the heating system. The difference to the heating system of FIG 1 is that in the design of FIG 6 The inductive heating device 3 is arranged outside the high-temperature heat storage unit 1. Accordingly, the heating system for charging the high-temperature heat storage unit 1—that is, for supplying thermal energy to the high-temperature heat storage unit 1—comprises a second line system 12. The high-temperature heat storage unit 1 and the inductive heating device 3 are fluidly connected to one another via the second line system 12. A second gas 13 can thus be conducted from the inductive heating device 3 to the high-temperature heat storage unit 1 in the second line system 12. The second line system 12 thus forms a second closed circuit for the second gas 13.

[0035] Analogous to the first gas 9, the second gas 13 in the high-temperature heat storage device 1 flows along contact surfaces of the storage material 4 located in the high-temperature heat storage device 1. Likewise, the second gas 13 in the inductive heating device 3 flows along a heating element 14. The heating element 14 is the element of the inductive heating device 3 which is inductively heated as such, and in which the electrical eddy currents are generated. For this reason, the second gas 13 is selected such that it is inert with respect to the contact surfaces of the storage material 4 and with respect to the heating element 14, i.e. it does not react chemically. In many cases, the second gas 13 - analogous to the first gas 9 - can consist of water vapor (H 2 O) and / or carbon dioxide (CO 2 ). The heating element 14 can, for example, be made of stainless steel, for example stainless steel 316L.Other materials are also possible, for example titanium, Alloy C286, zirconium (especially Zr 702) or tantalum.

[0036] It is possible that there is a complete or at least extensive separation of the gases 9, 13. For example, according to FIG 6 Within the high-temperature heat storage device 1, a partition wall 15 may be present, which is thermally bridged by heat-conducting elements (not shown). In this case, there is a complete separation of the gases 9, 13. The partition wall 15 may also be perforated, so that a separation of the gases 9, 13 is achieved to a certain extent. This may be necessary in particular if the high-temperature heat storage device 1 is designed as a stratified storage device and the first gas 9 is withdrawn from the high-temperature heat storage device 1 in the upper region 10 and fed back in the lower region 11. This is because the first gas 9 flows, as in FIG 6 indicated by an arrow 16, from bottom to top within the high-temperature heat storage device 1. In the case of the stratified storage device design, however, the second gas 13 is taken from the high-temperature heat storage device 1 in the lower region 10 for charging and, after flowing through the inductive heating device 3, is fed back into the upper region 11. This is because the second gas 13 flows, as shown in FIG 6 As indicated by an arrow 17, from top to bottom within the high-temperature heat storage unit 1. The direction of the two gas flows is thus inverse to each other.

[0037] In the case of the design of FIG 6 The first and second line systems 8, 12 are separate line systems. In particular, in the case of complete separation, even within the high-temperature heat storage unit 1, the second gas 13 can, as required, have the same chemical composition as the first gas 9 or a different chemical composition than the first gas 9. However, it is also possible for the first and second line systems 8, 12 to have common sections. In this case, the second gas 13 is necessarily identical to the first gas 9. In particular, the two gases 9, 13 can also mix with each other. The distinction between the first gas 9 and the second gas 13 is, in this case, merely linguistic. They are one and the same gas. Possible embodiments in which the two line systems 8, 12 have common sections are described below in connection with the FIG 7 and 8 explained.

[0038] In the design of the heating system according to FIG 7 The two line systems 8, 9 have sections 18 to 22 and branches 23, 24. The inductive heating device 3 is arranged in section 18. Adjustable elements 25, 26 are arranged in sections 19 and 20. The elements 25, 26, like the inductive heating device 3, can be controlled by a control device 27. The adjustable elements 25, 26 can, for example, comprise fans and / or shutters.

[0039] In the design according to FIG 7 Sections 18 and 21 are common sections, sections 19 and 22 are components exclusively of the first line system 8 and section 20 is a component exclusively of the second line system 12. If heat is to be supplied to the furnace 2 from the high-temperature heat accumulator 1 by the first gas 9, the first gas 9 flows via sections 18 and 19 to the furnace 2 and then via sections 22 and 21 back to the high-temperature heat accumulator 1. In this case, the adjustable element 25 is completely open and / or conveys the first gas 9. In this case, the adjustable element 26 is completely closed and / or does not convey any gas, in particular not the second gas 13. The inductive heating device 3 can be controlled or not controlled as required, depending on whether and, if so, to what extent the first gas 9 taken from the high-temperature heat accumulator 1 is to be further heated before being fed to the furnace 2.Conversely, if heat is to be supplied to the high-temperature heat accumulator 1 by the second gas 13, the second gas 13 flows via the sections 21 and 20 and a part of the section 18 to the inductive heating device 3 and then via the remaining part of the section 18 back to the high-temperature heat accumulator 1. In this case, the adjustable element 26 is completely open and / or conveys the second gas 13. In this case, the adjustable element 25 is completely closed and / or does not convey any gas, in particular not the first gas 9. In this case, the inductive heating device 3 is controlled such that it heats the second gas 13.

[0040] It is also possible that a further adjustable element 28 is additionally arranged in one of the sections 18 and 21, in particular a fan, and optionally also an additional closure flap.

[0041] In the design according to FIG 7 The extent to which the second gas 13 heated by the inductive heating device 3 is fed to the high-temperature heat accumulator 1 and / or the furnace 2 can thus be adjusted by means of the adjustable elements 25, 26 and optionally 28 by the control device 27.

[0042] In the design of the heating system according to FIG 8 the two line systems have the same sections 18 to 22 and branches 23, 24 as in the design according to FIG 7 . In the form provided for in FIG 8 However, the inductive heating device 3 is arranged in section 20. The adjustable elements 25, 26 and 28 can be arranged in the same way as in the design of the heating system according to FIG 7 be arranged and designed.

[0043] Also in the design according to FIG 8 sections 18 and 21 are common sections, sections 19 and 22 are components exclusively of the first line system 8 and section 20 is a component exclusively of the second line system 12. If heat is to be supplied to the furnace 2 from the high-temperature heat accumulator 1 by the first gas 9, the first gas 9 flows via sections 18 and 19 to the furnace 2 and then via sections 22 and 21 back to the high-temperature heat accumulator 1. In this case, the adjustable element 25 is completely open and / or conveys the first gas 9. The adjustable element 26 can also be completely closed in this case and / or convey no gas, in particular not the second gas 13. In this case, the inductive heating device 3 is not controlled. However, it is also possible to control the inductive heating device 3 and the adjustable element 26 in such a way that they supply additional heat energy to the furnace 2 through the second gas 13.Conversely, if heat is to be supplied to the high-temperature heat accumulator 1 by the second gas 13, the second gas 13 flows via section 21 and part of section 20 to the inductive heating device 3 and then via the remaining part of section 20 and section 18 back to the high-temperature heat accumulator 1. In this case, the adjustable element 26 is completely open and / or conveys the second gas 13. The inductive heating device 3 is controlled in this case such that it heats the second gas 13. In this case, the adjustable element 25 can be completely closed and / or convey no gas, in particular not the first gas 9. However, it is also possible for the gas flow flowing through the inductive heating device 3 to be split at the branch 23, so that, starting from the inductive heating device 3, heat is supplied to the high-temperature heat accumulator 1 and the furnace 2 at the same time.For this purpose, the adjustable element 25 must be opened.

[0044] Intermediate states are also possible. As a result, the control device 27 can adjust the extent to which the first gas 9 extracted from the high-temperature heat accumulator 1 and / or the second gas 13 heated by the inductive heating device 3 is supplied to the furnace 2.

[0045] The storage elements 5 can, as already mentioned, be spherical. Corresponding storage elements 5 are shown in the FIG 9 bis 11 shown.

[0046] In the design according to the FIG 9 und 10 The storage elements 5 have an outer shell 29 and an inner core 30. The inner core 30 completely fills the outer shell 29 (possibly with the exception of a small residual volume 31). A phase transition temperature of the inner cores 30 is below a melting temperature of the outer shells 29. This makes it possible, for example, for the inner cores 30 of the storage elements 5 to be in a first phase state (for example, in the solid state) when the storage elements 5 are at temperature T1. This state is in FIG 9 When the storage elements 5 are at temperature T2, the inner cores 30 are in a second phase state (for example, they may be molten). This state is shown in FIG 10 This embodiment can be particularly advantageous if the inner cores 30 are made of the same material as the material 6 located in the furnace 2. However, it is also possible for the inner cores 30 to be made of the same material as the material 6 located in the furnace 2, but for no phase transformation to occur during heating and cooling. In some embodiments - not shown in the FIGS - it can also be useful for the inner cores 30 to consist of a mixture of several substances and for the proportions of the substances to vary with the temperature of the high-temperature heat storage device 1, so that a chemical equilibrium is established whose equilibrium position depends on the temperature T.

[0047] In the design according to FIG 11 The storage elements 5 are uniform, i.e., not divided into outer shells 29 and inner cores 30. In such cases, the storage material 4 can be, in particular, a ceramic.

[0048] In some cases, the storage material 4 can also be made of graphite. In this case, however, the first and second gases 9, 13 must be selected appropriately. If the first and second gases 9, 13 contain carbon dioxide or water vapor, the use of graphite at high temperatures can lead to the formation of carbon monoxide, which should be avoided if possible.

[0049] The present invention offers many advantages. In particular, it enables comparatively energy-efficient heating of goods 6, whereby technological properties—particularly metallurgical properties—of the goods 6 can be advantageously influenced, and peak loads on an electrical supply network can be avoided or at least reduced. Furthermore, the associated high-temperature heat storage device 1 can be constructed very compactly.

[0050] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. List of reference symbols

[0051] 1High-temperature heat storage 2Furnace 3Heating device 4Storage material 5Storage elements 6Material 7Conveying direction 8, 12Pipe systems 9, 13Gases 10, 11Areas 14Heating element 15Partition wall 16, 17Flow directions 18 to 22Sections 23, 24Branches 25, 26, 28Adjustable elements 27Control device 29Outer shells 30Inner cores 31Residual volume T, T1, T2 temperatures

Claims

1. A heating system, - wherein the heating system comprises a high-temperature heat accumulator (1) and a furnace (2), - wherein the heating system for heating a material (6) located in the furnace (2) comprises a first line system (8), via which the high-temperature heat accumulator (1) and the furnace (2) are fluidically connected to one another, so that in the first line system (8) a first gas (9) can be guided from the high-temperature heat accumulator (1) to the furnace (2) and back in a first closed circuit, - wherein the first gas (9) is inert with respect to contact surfaces of the storage material (4) located in the high-temperature heat accumulator (1) and with respect to the material (6) located in the furnace (2), and - wherein the heating system comprises an inductive heating device (3), by means of which thermal energy can be supplied to the high-temperature heat accumulator (1).

2. Heating system according to claim 1, characterized by thatthe inductive heating device (3) is arranged in the high-temperature heat storage device (1).

3. Heating system according to claim 1, characterized by - that the heating system for charging the high-temperature heat accumulator (1) comprises a second line system (12) via which the high-temperature heat accumulator (1) and the inductive heating device (3) are fluidically connected to one another, so that in the second line system (12) a second gas (13) can be guided from the inductive heating device (3) to the high-temperature heat accumulator (1) and back in a second closed circuit, - wherein the second gas (13) is inert with respect to the contact surfaces of the storage material (4) located in the high-temperature heat accumulator (1) and of an inductively heated heating element (14) located in the heating device (3).

4. Heating system according to claim 3, characterized by thatthe first and second line systems (8, 12) have common sections (18, 21) and that the second gas (13) is identical to the first gas (9).

5. Heating system according to claim 4, characterized by that the first and / or the second line system (8, 12) has elements (25, 26, 28) which can be adjusted by a control device (27), so that the control device (27) can adjust the extent to which the first gas (9) taken from the high-temperature heat accumulator (1) and / or the second gas (13) heated by the inductive heating device (3) is supplied to the furnace (2).

6. Heating system according to claim 4, characterized by thatthe first and / or the second line system (8, 12) has elements (25, 26, 28) which can be adjusted by a control device (27), so that the control device (27) can adjust the extent to which the second gas (13) heated by the inductive heating device (3) is fed to the high-temperature heat accumulator (1) and / or the furnace (2).

7. Heating system according to one of claims 3 to 6, characterized by - that the high-temperature heat storage device (1) is designed as a stratified storage device, - that the first gas (9) is taken from the high-temperature heat storage device (1) in an upper region (11) for heating the material (6) located in the furnace (2) and is fed back into a lower region (10) after flowing through the furnace (2), and - thatthe second gas (13) is taken from the high-temperature heat accumulator (1) in the lower region (10) for charging and is fed back into the upper region (11) after flowing through the inductive heating device (3).

8. Heating system according to one of claims 1 to 6, characterized by that the high-temperature heat accumulator (1) is designed as a stratified accumulator, from which the first gas (9) is withdrawn in an upper region (11) for heating the material (6) located in the furnace (2) and is fed back into a lower region (10) after flowing through the furnace (2).

9. Heating system according to one of the above claims, characterized by that the storage material (4) in the high-temperature heat storage device (1) consists of spherical storage elements (5).

10. Heating system according to claim 9, characterized by thatthe storage elements (5) have an outer shell (29) and an inner core (30) and that a phase transformation temperature of the inner cores (30) is below a melting temperature of the outer shells (29) and / or the cores (30) consist of the same material as the material (6) located in the furnace (2) or that the inner cores (30) consist of a mixture of several substances and the proportions of the substances vary with the temperature (T) of the high-temperature heat storage device (1).

11. Heating system according to one of claims 1 to 9, characterized by that the storage material (4) is a ceramic.

12. Heating system according to one of the above claims, characterized by that the furnace (2) is designed such that the material (6) located in the furnace (2) is a rolled product made of metal, in particular steel.

13. Heating system according to claim 12, characterized by thatthe furnace (2) is designed such that the rolling stock is formed as a flat, elongated rolling stock.

14. Heating system according to one of the above claims, characterized by that the first gas (9) consists of water vapor and / or carbon dioxide.

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