Heating system with high-temperature heat store

Abstract

A heating system comprises a high-temperature heat store (1) and a furnace (2). The high-temperature heat store (1) is a heat store in which a storage material (4) located in the heat store (1) can be heated to temperatures of 1000 °C or more. In order to heat a material (6) located in the furnace (2), the heating system comprises a first line system, via which the high-temperature heat store (1) and the furnace (2) are fluidically connected to one another. In this way, a gas (9) can be conducted in the first line system (8) from the high-temperature heat store (1) to the furnace (2) and back in a first closed circuit. The heating system comprises an inductive heating device (3), by means of which thermal energy can be supplied to the high-temperature heat store (1). The gas (9) is inert in relation to contact surfaces of the storage material (4) in the high-temperature heat store (1), in relation to an inductively heated heating body (14) in the heating device (3) and in relation to the material (6) located in the furnace (2). In order to charge the high-temperature heat store (1), the heating system comprises a second line system, via which the high-temperature heat store (1) and the inductive heating device (3) are fluidically connected to one another, such that the gas (9) in the second line system can be conducted from the inductive heating device (3) to the high-temperature heat store (1) and back in a second closed circuit. The first and the second line system have common sections (18, 21).

Description

[0001] Description

[0002] Title of the invention

[0003] Heating system with high temperature heat storage

[0004] field of technology

[0005] The present invention is based on a heating system,

[0006] - the heating system comprising a high-temperature heat storage unit and a furnace,

[0007] - the high-temperature heat storage device is a heat storage device in which a storage material located in the heat storage device can be heated to temperatures of 1000 °C and more,

[0008] - wherein 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 gas can be guided from the high-temperature heat storage device to the furnace and back in a first closed circuit,

[0009] - wherein the heating system comprises an inductive heating device by means of which thermal energy can be supplied to the high-temperature heat storage device,

[0010] - wherein the gas is inert with respect to contact surfaces of the storage material located in the high-temperature heat storage device, with respect to an inductively heated heating element located in the heating device and with respect to the material located in the furnace,

[0011] State of the art

[0012] Such a heating system is known, for example, from WO 96 / 17215 A1 or the corresponding EP 0 750 170 A1.

[0013] DE 102008 044280 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.

[0014] EP 2 738 502 A1 discloses a bell-type annealing furnace in which several coils are arranged. A protective gas circulates within the bell-type annealing furnace, which is heated either by a conventional burner or electrically. A high-temperature heat storage device is not mentioned. The electrical heating is not inductive, but rather via heat radiators.

[0015] DE 102021 128 851 A1 discloses a heating system in which a rolled stock is heated in a furnace. Heating occurs using a transport medium, which may consist of carbon dioxide and water vapor. The transport medium is heated by concentrated solar radiation. Additionally, a heat storage device may be provided in which heat can be temporarily stored and later transferred to the stock in the furnace.

[0016] WO 2020 / 239288 A1 discloses a system comprising a high-temperature heat storage device. In the high-temperature heat storage device, a storage material is heated by an inductive heating device. A fluid flows through the high-temperature heat storage device, which is integrated into a cycle with another device. In particular, the fluid is used to drive a turbine with a downstream generator. Storage elements located in the high-temperature heat storage device can be spherical and, as required, made of ceramic or steel.

[0017] Summary of the invention

[0018] 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.

[0019] 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. Furthermore, this approach can only lead to a reduction in carbon dioxide emissions if the hydrogen was 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.

[0020] 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.

[0021] In particular, the teaching known from WO 96 / 17215 A1 already represents a significant improvement over the current state of the art.

[0022] The object of the present invention is to create a heating system that further improves the teachings of the aforementioned WO document. In particular, it enables efficient charging of the high-temperature heat storage tank in a simple and flexible manner and with minimal wiring effort.

[0023] 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 10. According to the invention, a heating system of the type mentioned at the outset is designed in that

[0024] - that the heating system for charging the high-temperature heat storage device comprises a second line system via which the high-temperature heat storage device and the inductive heating device are fluidically connected to one another, so that the gas in the second line system can be guided from the inductive heating device to the high-temperature heat storage device and back in a second closed circuit, and

[0025] - that the first and second pipe systems have common sections.

[0026] In particular, the use of closed circuits allows the gas to be selected as needed. Furthermore, the use of a high-temperature heat storage system 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 system, in turn, enables efficient, cost-effective heating of the high-temperature heat storage system. Heating can be decoupled from the thermal energy drawn from the high-temperature heat storage system, so that power peaks can be completely avoided or at least largely reduced. Furthermore, the arrangement and design of the inductive heating system can be determined independently of the furnace's specific conditions—with the exception of the required heating output.

[0027] 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.

[0028] The heat capacity of the high-temperature heat storage unit and the inductive heating output should be matched to the maximum power requirement of the furnace. For typical industrial furnaces in the metal industry, the maximum thermal power requirement of the furnace is typically between 20 and 100 MW. The inductive thermal heating output of the induction heater should be at least 20% of the maximum power requirement of the furnace. It can also be higher, for example, 30%, 40%, etc. More than 150% of the maximum power requirement of the furnace is generally not necessary. In most cases, even a value of 100% (plus / minus 10%) is sufficient. Similarly, the storage capacity of the storage unit should be matched to the maximum power requirement of the furnace.The storage capacity of the storage unit should be dimensioned such that the furnace can draw its maximum thermal power requirement from the high-temperature heat storage unit for at least 30 minutes, and better still, for at least 1 hour. In an advantageous embodiment, the first and / or second line system have elements that can be adjusted by a control device, so that the control device can adjust the extent to which the gas drawn from the high-temperature heat storage unit and / or the gas heated by the inductive heating unit is fed to the furnace. This enables what is known as peak shaving, i.e., avoiding load peaks on the inductive heating unit, even with a relatively small high-temperature heat storage unit.

[0029] Alternatively, it is possible for the control device to use the adjustable elements to adjust the extent to which the gas heated by the inductive heating device is fed to the high-temperature heat storage unit 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 unit.

[0030] 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.

[0031] The high-temperature heat storage device is preferably designed as a stratified storage device. In this case, the gas is extracted from the high-temperature heat storage device in an upper area to heat the material in the furnace and, after flowing through the furnace, is returned to a lower area. Similarly, the gas is extracted from the high-temperature heat storage device in the lower area for charging and, after flowing through the inductive heating device, is returned to the upper area. 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.

[0032] 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.

[0033] 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.

[0034] The storage material, unless divided into a shell and core, is preferably a ceramic. Ceramics can be heated to very high temperatures without cracking.

[0035] 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).

[0036] In many cases, it is advantageous if the 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 gas without any further modification.

[0037] Short description of the drawings

[0038] 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.

[0039] FIG 1 a heating system,

[0040] FIG 2 is a plan view of a furnace,

[0041] FIG 3 shows a section through the furnace of FIG 2 along a line lll-lll in FIG 2,

[0042] FIG 4 shows a section through the furnace of FIG 2 along a line IV-IV in FIG 2,

[0043] FIG 5 a high-temperature heat storage,

[0044] FIG 6 another heating system and

[0045] FIG 7 to 9 sections through storage elements.

[0046] Description of the embodiments

[0047] According to FIG 1, a heating system comprises a high-temperature heat storage unit 1, a furnace 2 and an inductive heating device 3.

[0048] The high-temperature heat storage device 1 contains a storage material 4. In individual cases, the storage material 4 can be a liquid storage medium. However, the storage material 4 is generally in a solid state. For example, the storage material 4 can consist of spherical storage elements 5 as shown in FIG. 1. 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.

[0049] 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 a flat, elongated rolled product, as shown in FIGS. 2 to 4. 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 indicated by an arrow 7 in FIGS. 2 and 3.

[0050] To heat the material 6 contained in the furnace 2, the heating system comprises a first piping system. The high-temperature heat storage unit 1 and the furnace 2 are fluidly connected via the first piping system. A gas 9 can be conducted from the high-temperature heat storage unit 1 to the furnace 2 and back in the first piping system. The first piping system thus forms a first closed circuit for the gas 9.

[0051] The 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 gas 9 flows in the furnace 2 along the material 6 located in the furnace 2. For this reason, the gas 9 is selected such that it is inert with respect to the contact surfaces of the storage material 4 and with the material 6, i.e., it does not react chemically. In many cases—particularly when the material 6 is a rolled stock—the gas 9 can consist of water vapor (H2O) and / or carbon dioxide (CO2). Especially for heating a rolled stock, the gas 9 should be free of nitrogen or at least contain as little nitrogen as possible (maximum 25 percent by volume).

[0052] Preferably, the high-temperature heat storage device 1 is designed as a stratified storage device, as shown in FIG. 5. The storage material 4 located in the high-temperature heat storage device 1 thus has a temperature T1 in a lower region 10 and a temperature T2 in an upper region 11, wherein the temperature T2 is greater than the 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 gas 9 is extracted in the upper region 11 and fed to the furnace 2 via the first line system. There, the gas 9 flows through the furnace 2 and thus heats the material 6 located in the furnace 2. The gas 9 cools as a result. After flowing through the furnace 2, the gas 9 is fed back to the high-temperature heat storage device 1 via the first line system, specifically in the lower region 10.

[0053] Thermal energy can be supplied to the high-temperature heat storage unit 1 by means of the inductive heating device 3. 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—i.e., for supplying thermal energy to the high-temperature heat storage unit 1—comprises a second line system. The high-temperature heat storage unit 1 and the inductive heating device 3 are fluidly connected to one another via the second line system. In the second line system 12, the gas 9 can be conducted from the inductive heating device 3 to the high-temperature heat storage unit 1. The second line system thus forms a second closed circuit for the gas 9.

[0054] The gas 9 flows past a heating element 14 in the inductive heating device 3. The heating element 14 is the element of the inductive heating device 3 that is inductively heated, i.e., in which the electrical eddy currents are generated. For this reason, the gas 9 is selected such that it is also inert with respect to the heating element 14, i.e., it does not react chemically. The heating element 14 can be made of stainless steel, for example, stainless steel type 316L. Other materials are also possible, for example, titanium, Alloy C286, zirconium (especially Zr 702), or tantalum.

[0055] The high-temperature heat storage device 1 is preferably designed as a stratified storage device. To draw thermal energy from the high-temperature heat storage device 1, the gas 9 is withdrawn in the upper region 10 and fed back in to the lower region 11. As a result, in this operating state, the gas 9 flows from bottom to top within the high-temperature heat storage device 1. For charging, the gas 9 is withdrawn from the high-temperature heat storage device 1 in the lower region 10 and, after flowing through the inductive heating device 3, fed back in to the upper region 11. As a result, in this operating state, the gas 9 flows from top to bottom within the high-temperature heat storage device 1. The direction of the two gas flows is therefore inverse to one another.

[0056] The first and second conduit systems have common sections. In the embodiment of the heating system according to FIG. 1, the two conduit systems 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 comprise, for example, fans and / or shutters.

[0057] In the embodiment according to FIG 1, sections 18 and 21 are common sections, sections 19 and 22 are components exclusively of the first line system, and section 20 is a component exclusively of the second line system. If heat is to be supplied to the furnace 2 from the high-temperature heat accumulator 1 via the gas 9, the 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 fully open and / or conveys the gas 9. In this case, the adjustable element 26 is fully closed and / or conveys no gas. The inductive heating device 3 can be controlled or not controlled as required, depending on whether and, if so, to what extent the 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 storage device 1 by the gas 9, the gas 9 flows via sections 21 and 20 and a portion of section 18 to the inductive heating device 3 and then via the remaining portion of section 18 back to the high-temperature heat storage device 1. In this case, the adjustable element 26 is fully open and / or conveys the gas 9. In this case, the adjustable element 25 is fully closed and / or does not convey any gas. In this case, the inductive heating device 3 is controlled such that it heats the gas 9.

[0058] 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.

[0059] In the embodiment according to FIG 1, the control device 27 can thus adjust by means of the adjustable elements 25, 26 and optionally 28 the extent to which the gas 9 heated by the inductive heating device 3 is fed to the high-temperature heat accumulator 1 and / or the furnace 2.

[0060] In the embodiment of the heating system according to FIG 6, the two line systems have the same sections 18 to 22 and branches 23, 24 as in the embodiment according to FIG 1. In the embodiment according to FIG 6, however, the inductive heating device 3 is in the section

[0061] 20. The adjustable elements 25, 26 and 28 can be arranged and designed in the same way as in the embodiment of the heating system according to FIG. 1.

[0062] 6, sections 18 and 21 are common sections, sections 19 and 22 are components exclusively of the first line system, and section 20 is a component exclusively of the second line system. If heat is to be supplied to the furnace 2 from the high-temperature heat accumulator 1 via the gas 9, the 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 gas 9. The adjustable element 26 can also be completely closed in this case and / or convey no gas. 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 via the gas 9.Conversely, if heat is to be supplied to the high-temperature heat storage unit 1 by the gas 9, the gas 9 flows over the section.

[0063] 21 and a 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 fully open and / or conveys the gas 9. In this case, the inductive heating device 3 is controlled such that it heats the gas 9. In this case, the adjustable element 25 can be fully closed and / or not convey any gas. 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.

[0064] 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.

[0065] As already mentioned, the storage elements 5 can be spherical. Corresponding storage elements 5 are shown in FIGS. 7 to 9.

[0066] In the embodiment according to FIGS. 7 and 8, 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 shown in FIG. 7. If, however, 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. 8.This configuration 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 no phase transformation occurs during heating and cooling. In some configurations - not shown in the figures - it can also be useful for the inner cores 30 to consist of a mixture of several substances and 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.

[0067] In the embodiment according to FIG. 9, 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.

[0068] 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.

[0069] The present invention has 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.

[0070] 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.

[0071] List of reference symbols

[0072] 1 high-temperature heat storage

[0073] 2 ovens

[0074] 3 Heating device

[0075] 4 Storage material

[0076] 5 storage elements

[0077] 6 Good

[0078] 7 Conveying direction

[0079] 9 Gas

[0080] 10, 11 areas

[0081] 14 radiators

[0082] 15 Partition wall

[0083] 16, 17 Flow directions

[0084] 18 to 22 sections

[0085] 23, 24 branches

[0086] 25, 26, 28 adjustable elements

[0087] 27 Control device

[0088] 29 outer shells

[0089] 30 inner cores

[0090] 31 residual volume

[0091] T, T1, T2 temperatures

Claims

Claims 1. Heating system, - wherein the heating system comprises a high-temperature heat accumulator (1) and a furnace (2), - wherein the high-temperature heat storage device (1) is a heat storage device in which a storage material (4) located in the heat storage device (1) can be heated to temperatures of 1000 °C and more, - wherein the heating system for heating a material (6) located in the furnace (2) comprises a first line system, 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 a 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 heating system comprises an inductive heating device (3) by means of which heat energy can be supplied to the high-temperature heat accumulator (1), - wherein the gas (9) is inert with respect to contact surfaces of the storage material (4) located in the high-temperature heat storage device (1), with respect to an inductively heated heating element (14) located in the heating device (3) and with respect to the material (6) located in the furnace (2), characterized in that - that the heating system for charging the high-temperature heat accumulator (1) comprises a second line system, via which the high-temperature heat accumulator (1) and the inductive heating device (3) are fluidically connected to one another, so that the gas (9) in the second line system can be guided from the inductive heating device (3) to the high-temperature heat accumulator (1) and back in a second closed circuit, and - that the first and the second line system have common sections (18, 21).

2. Heating system according to claim 1, characterized in that the first and / or the second line system have 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 gas (9) taken from the high-temperature heat accumulator (1) and / or the gas (9) heated by the inductive heating device (3) is supplied to the furnace (2).

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

4. Heating system according to claim 1, 2 or 3, characterized in that - that the high-temperature heat storage tank (1) is designed as a stratified storage tank, - that the gas (9) is taken from the high-temperature heat accumulator (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 - that the gas (9) 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).

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

6. Heating system according to claim 5, characterized in that the 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).

7. Heating system according to one of claims 1 to 5, characterized in that the storage material (4) is a ceramic.

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

9. Heating system according to claim 8, characterized in that the furnace (2) is designed such that the rolling stock is formed as a flat, elongated rolling stock.

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

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