Carnot battery having a heat generator, and method for converting energy by means of the carnot battery

Abstract

A Carnot battery (2), comprising a heat generator (8) for heating a fluid by electric current and a heat store (10) for storing heat of the fluid heated by the heat generator (8), wherein the Carnot battery (2) also comprises a converter (12) for converting the heat into electricity and / or a branch (13A) of the heat store (10) for providing the heated fluid, wherein the heat generator (8) has a plurality of tubes (18) between at least one inlet (14) and at least one outlet (16), wherein the tubes (18) are fluidically connected in parallel. At least one phase of the electric current is applied directly to the tubes (18) at an input terminal (20), and the input terminal (20) is arranged electrically between the at least one inlet (14) and the at least one outlet (16) of the heat generator (8), and an output terminal (22) for the electric current is connected to ground (G).

Description

[0001] Carnot battery with a heat generator and method for energy conversion using a Carnot battery

[0002] The present invention relates to a Carnot battery which comprises a heat generator for heating a fluid with electrical current.

[0003] The present invention also relates to a method for energy conversion using a Carnot battery.

[0004] Carnot batteries allow the storage of electrical energy by converting it into thermal energy. This general principle is also known as PTES (Pumped Thermal Energy Storage) or PHES (Pumped Heat Electrical Storage).

[0005] A Carnot battery converts an electrical current into heat, stores the heat in a storage medium such as water or molten salt, and converts the heat back into electricity when needed.

[0006] To convert electrical current into heat, heating loops are typically heated by the current and transfer the heat to a medium, such as water.

[0007] DE 10 2012 108 733 A1 discloses a system for generating hot water / steam with a high-temperature storage unit for use in a gas turbine power plant, wherein the energy for charging the high-temperature storage unit is provided from at least one external energy source and / or from an internal energy source of the gas turbine power plant.

[0008] CN 201 373 547 Y relates to an electric water heater in which water flows through several connected pipes, at the end caps of which electrical current is connected to a control system.

[0009] Such Carnot batteries can still be improved. In particular, the efficiency of Carnot batteries is not always optimal. This is especially true regarding their dynamic behavior. Storage in the form of heat, for example, is desirable when there is a surplus of electrical energy, but at a time when a subsequent process cannot utilize this heat.

[0010] Furthermore, known Carnot batteries are often quite large and heavy.

[0011] One aim of the present invention is to improve the efficiency, in particular the power factor, and / or the temporally flexible use of a Carnot battery. In particular, one object of the invention is to provide a Carnot battery that has high temporal efficiency and is compact.

[0012] According to the invention, this object is achieved by a Carnot battery, comprising a heat generator for heating a fluid with electrical current, a heat accumulator for storing heat of the fluid heated by the heat generator, wherein the Carnot battery further comprises a converter for converting the heat into electricity and / or a branch of the heat accumulator for providing the heated fluid, wherein the heat generator has a plurality of tubes between at least one inlet and at least one outlet, wherein the tubes are fluidically connected in parallel.

[0013] At least one phase of the electrical current is applied directly to the tubes at an input terminal, the input terminal being electrically arranged between the at least one inlet and the at least one outlet of the heat generator, an output terminal of the electrical current being connected to ground and connected to the at least one inlet and / or the at least one outlet.

[0014] Thanks to the Carnot battery according to the invention, efficiency is increased by minimizing the thermal capacities of the heat generator.

[0015] In addition, the Carnot battery allows for combined operation of both process heat and electricity generation according to temporal requirements and the availability of electrical energy.

[0016] According to preferred embodiments, the Carnot battery according to the invention comprises one, several or all of the following features, in all technically possible combinations:

[0017] - the heat storage device contains a heat storage material which comprises a salt;

[0018] - the tubes form a resistance heating device;

[0019] - the tubes extend along a respective tube axis, wherein the tube axes are arranged at least partially parallel to one another;

[0020] - at least one of the tubes comprises a compensation section which is designed to compensate for thermal stresses along a longitudinal direction of the tube;

[0021] - the fluid heated by the heat generator comprises steam and / or superheated water; - the heat generator comprises at least one evaporation part for evaporating water and at least one steam heating part for heating steam from the evaporation part;

[0022] - the heat generator further comprises a collector connecting the evaporation part to the steam heating part;

[0023] - the heat generator comprises at least three groups, each group comprising a plurality of tubes of the plurality of tubes, wherein the electric current is a three-phase current, a respective phase of the three-phase current being applied directly to the tubes of the corresponding group;

[0024] - the inlet clamp is arranged at a longitudinal position of each pipe, which is in the middle of the pipe in a longitudinal direction of the pipe or between the middle of the pipe and the inlet;

[0025] - the longitudinal position is selected depending on the operating pressure of the heat generator;

[0026] - the heat generator is positioned below or to the side of the heat storage tank;

[0027] - the input terminal and / or the output terminal is / are a distributor; the heat accumulator comprises a preheating part and a storage heating part, wherein the at least one outlet of the heat generator is connected to the heat accumulator via at least one transfer pipe, wherein the at least one transfer pipe comprises at least one branch arranged such that a fluid flow received from the outlet is divided into a first part for forwarding to the preheating part and a second part for forwarding to the storage heating part, wherein the second part is hotter than the first part.

[0028] The invention also relates to a method for energy conversion by means of a Carnot battery, wherein the Carnot battery comprises a heat generator for heating a fluid with electrical current, wherein the heat generator has a plurality of tubes between at least one inlet and at least one outlet, wherein the tubes are fluidically connected in parallel, wherein the method comprises at least one heating step in which at least one phase of the electrical current is applied directly to the tubes at an input terminal and the tubes generate heat by electrical resistance, wherein the input terminal is electrically arranged between the at least one inlet and the at least one outlet of the heat generator, wherein an output terminal of the electrical current is connected to ground and is connected to the at least one inlet and / or the at least one outlet.

[0029] According to a preferred embodiment, the method comprises several or all of the following features, in all technically possible combinations:

[0030] - the Carnot battery further comprises a heat accumulator for storing heat of the fluid heated by the heat generator, wherein the method further comprises a storage step in which the heat accumulator at least partially stores heat of the fluid heated by the heat generator;

[0031] - the Carnot battery further comprises a converter for converting the heat into electricity and / or a branch for providing the heated fluid, wherein the method further comprises a conversion step in which the converter at least partially converts the heat stored by the heat storage device into electricity.

[0032] Preferred embodiments of the invention will now be described in detail with reference to the drawings, in which: Figure 1 is a schematic view of a Carnot battery with a heat generator according to a first embodiment; Figure 2 is a schematic view of part of a Carnot battery with a heat generator according to a second embodiment; and Figure 3 is a schematic view of part of the Carnot battery of Figure 1, showing a heat accumulator of the Carnot battery according to a variant.

[0033] With reference to Figure 1, a plant 1 comprises a Carnot battery 2, an energy source 4 for providing an electric current, and piping 6.

[0034] The energy source 4 is an electrical energy source which is designed to provide an electrical current.

[0035] Electric current, for example, is an alternating current.

[0036] The electric current is in particular a three-phase current.

[0037] The Carnot battery 2 is designed to convert electrical current into heat, store the heat, and, for example, convert it back into electricity when needed. Alternatively, the stored heat can be supplied to a downstream process in the form of a heated fluid, for example, steam and / or superheated water. The Carnot battery 2 comprises a heat generator 8 for heating a fluid with the electrical current and, for example, a heat accumulator 10 for storing heat from the fluid heated by the heat generator 8.

[0038] The fluid heated by the heat generator 8 comprises, for example, steam and / or superheated water. According to one example, the heated fluid comprises a mixture of steam and superheated water.

[0039] “Superheated water” is a condition in which the temperature of the water is higher than the saturation temperature at the existing pressure.

[0040] Furthermore, the Carnot battery 2 comprises, for example, a converter 12 for converting the heat into electricity.

[0041] The Carnot battery 2 comprises, for example, at least one outlet pipe 13 which is designed to conduct the medium, in particular steam, from the heat accumulator 10 to the converter 12 and / or to a system part (not shown) which requires steam.

[0042] For example, the Carnot battery comprises a branch 13A, which is designed to provide the heated fluid, for example to forward the heated fluid to a downstream process or to the plant part (not shown) which requires the heated fluid, in particular steam.

[0043] The outlet pipe 13 and / or the branch 13A comprises / comprise, for example, one or more valves not shown.

[0044] For example, the heat generator 8 is positioned below or laterally below the heat accumulator 10. This enables at least partial natural convection of a medium, in particular steam, from the heat generator 8 into the heat accumulator 10, in particular without the use of a pump to pump the medium.

[0045] The term “below” here means an arrangement in which at least a part of the heat generator 8 is positioned at a lower level than each part of the heat accumulator 10, according to a vertical direction.

[0046] Figure 1 shows a schematic example of the Carnot battery 2 with a heat generator 8 according to a first embodiment. This first embodiment will now be described.

[0047] The heat generator 8 comprises at least one inlet 14, at least one outlet 16, as well as a plurality of tubes 18 between the inlet 14 and the outlet 16. The or each inlet 14 is configured to receive a medium, such as water in the liquid or gaseous state, and to conduct it into the tubes 18.

[0048] The or each outlet 16 is designed to receive the medium, in particular in the form of steam, from an end of the tubes 18 arranged opposite the inlet 14 and to convey the medium in the direction of the heat accumulator 10.

[0049] The pipes 18 are fluidically or flow-technically connected in parallel between the inlet 14 and the outlet 16.

[0050] For example, the tubes 18 extend along a respective tube axis. In particular, the tube axes of the tubes 18 are arranged at least partially parallel to one another. For example, all tube axes extend parallel to one another, preferably over at least 90% of a tube length or over an entire tube length between the inlet 14 and the outlet 16.

[0051] For example, each pipe 18 is between 2 and 50 meters long, according to the pipe axis.

[0052] For example, each tube 18 has a diameter between 6 and 40 mm.

[0053] According to one example, each tube 18 is made of metal.

[0054] According to one example, at least one of the tubes 18, preferably all of the tubes 18, comprises a compensation section. The compensation section is configured to compensate for thermal stresses along a longitudinal direction of the respective tube 18. The longitudinal direction corresponds, for example, to the tube axis.

[0055] According to one example, the compensation section comprises a spiral winding over at least part of the length of the tube 18. For example, the or each tube 18 is wound at least partially spirally.

[0056] According to one example, the or each tube 18 in the compensation section has a wall orientation of the tube 18 that forms an angle between 10° and 30°, for example 15°, with a plane oriented perpendicular to the tube axis. For example, the tube 18 is oriented vertically, and the wall of the tube 18 is oriented in the compensation section such that it forms an angle between 10° and 30°, for example 15°, with the horizontal.

[0057] Furthermore, the heat generator 8 comprises an input terminal 20 for applying the phase(s) of the electrical current to the pipes 18 and an output terminal 22 for discharging or grounding the current.

[0058] According to the invention, at least one phase of the electrical current is applied directly to the tubes 18 at the input terminal 20. The term "directly applied" means that the phase of the electrical current is conducted through the input terminal 20 directly into a wall of the respective tubes 18. The wall of the tubes 18 represents, in particular, a separation between a tube interior and an area surrounding the tube 18. The tube interior is provided for the flow of the medium. For example, the tube interior has a circular or, in the case of a spiral winding, an elliptical cross-section.

[0059] The input terminal 20 is electrically arranged between the respective inlet 14 and the respective outlet 16 of the heat generator 8.

[0060] For example, the inlet clamp 20 is arranged at a longitudinal position of each tube 18, which is located in the middle of the respective tube 18 in a longitudinal direction of the tube 18 or between the middle of the tube 18 and the inlet 14.

[0061] In particular, the longitudinal position, viewed from the inlet 14, is arranged in a range between 1 / 8 and half the length of the tube 18. When the inlet terminal 20 is arranged close to the inlet 14, for example, at 1 / 8 of the length of the tube 18, the tube 18 exhibits a higher heat flux generated by the electrical current in the region between the inlet terminal 20 and the inlet 14, compared to a heat flux generated by the current in the region between the inlet terminal 20 and the outlet 16.

[0062] According to one example, the longitudinal position of the inlet clamp 20 on the respective pipe 18 depends on an operating pressure of the heat generator 8.

[0063] For example, with increasing operating pressure, the longitudinal position of the inlet clamp 20 is shifted towards the center of the pipe 18.

[0064] According to one example, as also illustrated in Figure 1, the input clamp 20 is arranged in the middle of the pipe 18, for example at an operating pressure of 250 bar.

[0065] According to one example, the input terminal 20 is a manifold directly connected to a plurality of pipes 18. In particular, the input terminal 20 comprises a manifold extending orthogonally to a longitudinal direction of the pipes 18 and / or parallel to the inlet 14 and / or parallel to the outlet 16.

[0066] According to one example, the input terminal 20 comprises several sub-terminals which are applied directly to the pipes 18 of a respective group.

[0067] The output terminal 22 is connected on the one hand to the inlet 14 and / or the outlet 16, and on the other hand to the ground G.

[0068] For example, the output terminal 22 is electrically connected to both the inlet 14 and the outlet 16. In particular, the output terminal 22 is directly connected to a tube forming the inlet 14 and the outlet 16, respectively. The tubes 18 form, for example, a resistance heating device.

[0069] For example, the input terminal 20 is configured to deliver at least one phase of the electrical current to the tubes 18, wherein the current flows through the tubes 18, in particular the tube walls, and is diverted from the output terminal 22 to ground G. Due to the electrical resistance of the tube walls, the tubes 18 heat up when the input terminal 20 introduces the current into the tube walls.

[0070] According to one example, the output terminal 22 is a distributor. In particular, the output terminal 22 is directly electrically connected to the or each inlet 14 and the or each outlet 16.

[0071] According to one example, with reference to Figure 1, the heat generator 8 comprises at least three groups 24A, 24B, 24C. Each group 24A, 24B, 24C comprises a plurality of the tubes 18. According to one example, where the electric current is a three-phase current, a respective phase of this three-phase current is applied directly to the tubes 18 of the corresponding group 24A, 24B, 24C.

[0072] Each group 24A, 24B, 24C has, for example, an identical number of tubes 18, one inlet 14 each, and one outlet 16 each.

[0073] In particular, each group 24A, 24B, 24C is identical, with the respective input terminal 20 being adapted to conduct a respective phase of the three-phase current into the pipes 18 of the respective group 24A, 24B, 24C.

[0074] Preferably, each group 24A, 24B, 24C comprises at least one or more of the above-mentioned features of the heat generator 8.

[0075] According to a variant not shown, the heat generator 8 comprises only a single group, two groups or more than three groups.

[0076] The heat accumulator 10 is configured to receive the medium, in particular steam, from the heat generator 8 and / or from a steam-generating process (not shown). The heat accumulator 10 is configured, in particular, to store the thermal energy of the steam or superheated water in the salt and, when needed, to make the stored thermal energy available again, at least in part, in the form of steam.

[0077] The heat storage device 10 contains, in particular, a heat storage material for storing heat. The heat storage material comprises, for example, a salt, which is, for example, a molten salt. The salt comprises, for example, a mixture of different salts.

[0078] The heat accumulator 10 further comprises, for example, a plurality of heat exchanger elements 25, for example in the form of tubes. The salt is arranged, for example, between the heat exchanger elements 25. The heat exchanger elements 25 are configured to receive steam from the heat generator and / or from the steam-generating process (not shown) and to transfer the heat of the steam to the salt or to carry out a heat exchange. In particular, the steam condenses at least partially during this heat exchange, and the heat storage material, for example in the form of salt, melts. The heat accumulator 10 is further configured to discharge the condensed steam in the form of water via a discharge line 36.

[0079] The heat accumulator 10 is further configured to generate steam, particularly when electrical energy is needed. For example, the heat accumulator 10 is configured to receive water via a supply line 37 and to evaporate it in the heat exchanger elements 25 by exchanging it with the heat stored in the heat accumulator material. In this case, the heat accumulator 10 is further configured, for example, to deliver the steam or superheated water thus generated to the converter 12 and / or a part of the system 1 (not shown) that requires steam or superheated water.

[0080] The converter 12 comprises, for example, a turbine and a generator for generating electricity from the heat previously stored in the heat storage unit 10. The turbine is particularly configured to receive heat in the form of steam from the heat storage unit 10 and, with the aid of the generator, to convert it into electrical energy.

[0081] The piping 6 of the system 1 comprises, for example, an inlet 26 of the medium, in particular water, and a pump 28 which is arranged in the inlet 26 and is designed to pump the medium towards the inlet(s) 14 of the heat generator 8.

[0082] According to another example, the piping 6 does not include a pump. In this case, a mass flow of the medium is achieved by natural convection, with the heat generator generating warm fluid that rises due to the temperature increase. This is then cooled in the heat accumulator 10. This produces, in particular, cold and thus heavy water, which flows downward to the inlet of the heat generator.

[0083] The piping 6 further comprises a plurality of valves for shutting off corresponding pipe sections, in particular in order to implement the various operating modes.

[0084] The piping 6 further comprises transfer pipes 30, which are configured to conduct the medium, in particular steam or superheated water, from the outlet(s) 16 to the heat accumulator 10. The piping 6 further comprises, for example, an inlet 32, which is suitable for supplying steam or superheated water from the heat-generating process (not shown) to the heat accumulator 10.

[0085] The piping 6 further comprises, for example, the drain line 36, which is designed to drain condensed steam or cooled water from the heat accumulator 10.

[0086] The piping 6 further comprises, for example, the supply line 37, which is connected to the inlet 26 and / or the pump 28 and is designed to supply the heat storage unit 10 with water.

[0087] A method for energy conversion using the Carnot battery 2 will now be described. The method comprises at least one heating step, one storage step, and one conversion step.

[0088] During the heating step, at least one phase of the electrical current is applied directly to the tubes 18 at the respective input terminal 20.

[0089] For example, the electrical power delivered to the tubes 18 is controlled or monitored by an electrical converter. In particular, the converter controls the amount of heat per unit time that the tubes 18 generate through their electrical resistance.

[0090] The respective phase of the electrical current is conducted from the input terminal 20 into the tubes 18 to the inlet 14 and / or the outlet 16 and is discharged via the output terminal 22 to ground G. The tubes 18 generate heat due to electrical resistance as the current flows.

[0091] The medium, in particular water, flows from the inlet 26 into the or each inlet 14, through the tubes 18, and is thereby evaporated by the heat of the tubes 18. The steam flows through the or each outlet 16 and the transfer tubes 30 into the heat storage unit 10.

[0092] During the storage step, the heat storage device 10 at least partially stores heat from the steam generated by the heat generator 8. In particular, the heat storage material, for example, the salt, absorbs the heat from the steam and stores it.

[0093] During the conversion step, the converter 12 converts the heat stored by the heat accumulator 10 at least partially into electricity, in particular into an electric current. The heat accumulator 10 initially generates steam. For example, the heat accumulator 10 receives water via the supply line 37 and evaporates it in the heat exchanger elements 25 by exchanging heat with the heat stored in the heat accumulator material. The heat accumulator 10 transports the resulting steam to the converter 12 and / or the part of the system 1 (not shown) that requires steam.

[0094] The converter, in particular the turbine, receives, for example, the steam from the heat storage 10 and converts the thermal energy in the steam into electrical energy with the help of the generator.

[0095] With reference to Figure 2, the Carnot battery 2 with the heat generator 8 according to a second embodiment will now be described. For example, the Carnot battery 2 comprises at least some, preferably all, features of the first embodiment, with the exception of the features of the heat generator 8 described below.

[0096] The same or similar features of the Carnot battery 2 according to the second embodiment compared to the first embodiment are not described again. In particular, only part of the energy source 4 and part of the heat generator 8 are shown in Figure 2, with the other elements of the Carnot battery 2 being analogous to the elements of Figure 1.

[0097] The same reference numerals are used for the same or similar elements of the Carnot battery 2 according to the second embodiment compared to the first embodiment.

[0098] According to the second embodiment, the heat generator 8 comprises at least one evaporation part 38 for evaporating the medium, in particular water, and further comprises at least one steam heating part 40 for heating steam from the evaporation part 38. The heat generator 8 further comprises, for example, a collector 42 which connects the evaporation part 38 to the steam heating part 40.

[0099] The evaporation section 38 is configured to receive the medium, in particular water, through the inlet 14, evaporate it, and deliver it in the form of steam to the collector 42. The steam heating section 40 is configured to receive the steam from the collector 42, further heat it, and deliver it to the outlet 16.

[0100] The evaporation section 38 and / or the steam heating section 40 each comprise the corresponding tubes 18, to which the input terminal 20 is attached to conduct the electrical current directly to the tubes 18. The output terminal 22 is, in particular, directly electrically connected to the inlet 14, the outlet 16, and possibly additionally to the collector 42. In this case, for example, the input terminal 20 and the output terminal 22 are implemented as distributors. Both the evaporation section 38 and the steam heating section 40 are configured to heat the medium by heating the tubes 18, to which the respective phase of the electrical current is directly applied.

[0101] For example, the evaporation part 38 and / or the steam heating part 40 each have an identical structure to the heat generator 8 according to the first embodiment, except that the evaporation part 38 is directly connected to the collector 42 instead of the outlet 16, and that the steam heating part 40 is directly connected to the collector 42 instead of the inlet 14.

[0102] The heat generator 8 according to the Carnot battery 2 of the second embodiment comprises, for example, at least three groups 24A, 24B, 24C. In this case, each group 24A, 24B, 24C comprises the evaporation part 38, the collector 42, and the steam heating part 40.

[0103] The collector 42 is designed, for example, to achieve pressure equalization and / or mixing of the medium.

[0104] A method for energy conversion by means of the Carnot battery 2 with the heat generator 8 according to the second embodiment preferably comprises all features of the method by means of the Carnot battery 2 of the first embodiment, with the exception of the features described below.

[0105] During the heating step, at least one phase of the electrical current is applied directly to the tubes 18 of both the evaporation section 38 and the steam heating section 40 at the respective input terminal 20. The respective phase of the electrical current is conducted from the input terminal 20 into the tubes 18 to the inlet 14, the collector 42, and / or the outlet 16, and is conducted via the output terminal 22 to ground G. The tubes 18 generate heat through electrical resistance as the current flows.

[0106] The medium, in particular water, flows from the inlet 26 (see in particular Figure 1) into the or each inlet 14, through the tubes 18 of the evaporation section 38, and is thereby evaporated by the heat of the tubes 18. The medium then flows through the collector 42 into the tubes 18 of the steam heating section 40. In the steam heating section 40, the medium (here in particular steam) is further heated by the heat of the tubes 18 and then flows into the or each outlet 16.

[0107] The further procedure is in particular as described above.

[0108] With reference to Figure 3, an example of the Carnot battery 2 according to the first embodiment will now be described, wherein the Carnot battery 2 includes the heat accumulator 10 according to a variant. The heat accumulator 10 according to the variant includes, for example, a preheating part 43 and a storage heating part 44.

[0109] For example, the preheating part 43 comprises a salt mixture as heat storage material, which has a different composition than the salt mixture arranged as heat storage material in the storage heating part 44. In particular, the preheating part 43 comprises a salt mixture adapted for a lower temperature than the salt mixture of the storage heating part 44.

[0110] According to one example, the transfer tubes 30 comprise a plurality of tubes connecting the or each outlet 16 of the heat generator 8 to the heat accumulator 10, in particular to heat exchanger elements 25. For example, each tube of the transfer tubes 30 connects the outlet 16 or one of the outlets 16 directly to a respective heat exchanger element 25. For example, each heat exchanger element 25 is connected to the outlet 16 via a tube of the transfer tubes 30 specifically assigned to it.

[0111] For example, the transfer tubes 30 comprise a plurality of branches 46 arranged such that a fluid flow of the medium, in particular steam or a water-steam mixture, received from the outlet 16 is divided into a first part and a second part. The first part is intended, in particular, for forwarding to the preheating part 43, and the second part is intended, in particular, for forwarding to the storage heating part 44. The second part is preferably hotter than the first part. During operation of the Carnot battery 2, the first part is therefore directed, in particular, to the preheating part 43 and the second part to the storage heating part 44.

[0112] For example, each branch 46 comprises a T-piece, with a horizontal portion of the T-piece diverting the first portion of the fluid flow toward the preheating section 43 and a vertically upward portion of the T-piece diverting the second portion of the fluid flow toward the storage heating section 44. This is particularly effective when the heated fluid is a mixture of water and steam. In this case, the T-piece separates the mixture into a flow with a predominant steam content and a flow with a predominant water content. The portion with the lower steam content has a lower heat transfer capacity. Therefore, this portion is fed to the preheating section 43. The remaining portion with a high heat transfer capacity has a good heat transfer capacity. Therefore, this portion is used to heat the storage heating section 44, which is brought to a higher temperature level.During storage, this portion is then used in particular to generate fluid at a higher enthalpy level, such as steam.

[0113] In particular, the heat storage unit 10 according to the variant comprises two parts 43, 44 with different temperatures and different salt mixtures as heat storage material. This particularly increases the efficiency of the heat storage unit 10.

[0114] Further features of the Carnot battery 2 with the heat accumulator 10 according to the variant of Figure 3 are, for example, identical to the Carnot battery 2 according to the first embodiment.

[0115] In another example, at least some or all of the features of the Carnot battery 2 with the heat storage 10 according to the variant of Figure 3 are according to the Carnot battery 2 of the second embodiment.

[0116] The present invention has a large number of advantages.

[0117] By applying the electrical current directly to the tubes 18, the Carnot battery 2 has a very short response time and can therefore be quickly charged, for example, in the event of a short-term surplus of electrical energy. In particular, the direct application of the current to the tubes 18 results in rapid heating of the water or steam. This allows the Carnot battery 2 to be used in particular in cases where a rapid conversion of electrical energy into heat is required, or where, for example, excess electrical energy is to be stored in the form of heat for only a short period of time.

[0118] Furthermore, the Carnot battery 2 is lightweight, especially since no additional heating spindles are required.

[0119] In addition, the total water consumption is low because the Carnot battery 2, and in particular the heat generator 8, are particularly compact.

[0120] In particular, the Carnot battery 2 has a high efficiency because a very large proportion of the electrical energy is converted directly into thermal energy.

[0121] The Carnot battery 2 is preferably designed to make the heated fluid available for subsequent use and / or to supply the converter 12 for generating electrical energy. Additionally, the supply is provided, for example, either by the electrically heated heat generator 8 or by storage from a molten salt bath. The subsequent use can, for example, consist of supplying steam or superheated water to a downstream process. Another form of use can be the conversion of the heat back into steam to generate electricity again by means of the converter 12. The generation of electrical energy preferably occurs at a time when there is an insufficient amount of electrical energy available in the grid.Due to this process, the Carnot battery enables an increase in efficiency, since at the time of excess electrical power capacity, steam or superheated water is generated very quickly without loss of preheating time or high thermal capacities.

[0122] The Carnot battery 2 makes it possible, in particular, to generate electrical power depending on the electrical energy capacity in the grid or, alternatively or simultaneously, to provide heat in the form of steam or superheated water in a downstream process. The available electrical energy in the grid is provided directly to the downstream process at a given time, depending on availability, or, in the event of excess capacity in the electrical grid, is temporarily stored in a heat storage unit. For example, in the event of an undercapacity in the electrical grid, this heat is extracted from the storage unit to generate steam or superheated water, which is then fed to the downstream process or to the converter 12 to generate electricity.

Claims

CLAIMS 1. A Carnot battery (2) comprising a heat generator (8) for heating a fluid with electrical current, a heat accumulator (10) for storing heat of the fluid heated by the heat generator (8), wherein the Carnot battery (2) further comprises a converter (12) for converting the heat into electricity and / or a branch (13A) of the heat accumulator (10) for providing the heated fluid, wherein the heat generator (8) has a plurality of tubes (18) between at least one inlet (14) and at least one outlet (16), wherein the tubes (18) are fluidically connected in parallel, characterized in that at least one phase of the electrical current is applied directly to the tubes (18) at an input terminal (20), wherein the input terminal (20) is electrically arranged between the at least one inlet (14) and the at least one outlet (16) of the heat generator (8),wherein an output terminal (22) of the electric current is connected to the ground (G) and is connected to the at least one inlet (14) and / or the at least one outlet (16).

2. Carnot battery (2) according to claim 1, wherein the heat storage (10) contains a heat storage material which comprises a salt.

3. Carnot battery (2) according to claim 1 or 2, wherein the tubes (18) form a resistance heating device.

4. Carnot battery (2) according to any one of the preceding claims, wherein the tubes (18) extend along a respective tube axis, the tube axes being arranged at least partially parallel to one another.

5. Carnot battery (2) according to any one of the preceding claims, wherein at least one of the tubes (18) comprises a compensation section which is adapted to compensate for thermal stresses along a longitudinal direction of the tube (18).

6. Carnot battery (2) according to any one of the preceding claims, wherein the fluid heated by the heat generator (8) comprises steam and / or superheated water.

7. Carnot battery (2) according to any one of the preceding claims, wherein the heat generator (8) comprises at least one evaporation part (38) for evaporating water and at least one steam heating part (40) for heating steam from the evaporation part (38), the heat generator (8) further comprising a collector (42) connecting the evaporation part (38) to the steam heating part (40).

8. Carnot battery (2) according to any one of the preceding claims, wherein the heat generator (8) comprises at least three groups (24A, 24B, 24C), each group (24A, 24B, 24C) comprising a plurality of tubes (18) of the plurality of tubes (18), wherein the electrical current is a three-phase current, a respective phase of the three-phase current being applied directly to the tubes (18) of the corresponding group (24A, 24B, 24C).

9. Carnot battery (2) according to any one of the preceding claims, wherein the inlet terminal (20) is arranged at a longitudinal position of each tube (18) which is located in the middle of the tube (18) in a longitudinal direction of the tube (18) or between the middle of the tube (18) and the inlet (14), preferably the longitudinal position being selected depending on an operating pressure of the heat generator (8).

10. Carnot battery (2) according to any one of the preceding claims, wherein the heat generator (8) is positioned below or laterally below the heat accumulator (10). 1 1. Carnot battery (2) according to any one of the preceding claims, wherein the input terminal (20) and / or the output terminal (22) is / are a distributor.

12. Carnot battery (2) according to any one of the preceding claims, wherein the heat accumulator (10) comprises a preheating part (43) and a storage heating part (44), wherein the at least one outlet of the heat generator (8) is connected to the heat accumulator (10) via at least one transfer pipe (30), wherein the at least one transfer pipe (30) comprises at least one branch (46) arranged such that a fluid flow received from the outlet (16) is divided into a first part for forwarding to the preheating part (43) and a second part for forwarding to the storage heating part (44), wherein the second part is hotter than the first part.

13. A method for energy conversion using a Carnot battery (2), wherein the Carnot battery (2) comprises a heat generator (8) for heating a fluid with electrical current, wherein the heat generator (8) has a plurality of tubes (18) between at least one inlet (14) and at least one outlet (16), wherein the tubes (18) are fluidically connected in parallel, wherein the method comprises at least one heating step in which at least one phase of the electrical current is applied directly to the tubes (18) at an input terminal (20), and the tubes (18) generate heat by electrical resistance, wherein the input terminal (20) is electrically arranged between the at least one inlet (14) and the at least one outlet (16) of the heat generator (8), wherein an output terminal (22) of the electrical current is connected to ground (G) and is connected to the at least one inlet (14) and / or the at least one outlet (16).

14. The method according to claim 13, wherein the Carnot battery (2) further comprises a converter (12) for converting the heat into electricity and / or a branch (13A) for providing the heated fluid, wherein the Carnot battery (2) further comprises a heat accumulator (10) for storing heat of the fluid heated by the heat generator (8), wherein the method further comprises a storage step in which the heat accumulator (10) at least partially stores heat of the fluid heated by the heat generator (8); wherein the method preferably further comprises a conversion step in which the converter (12) at least partially converts the heat stored by the heat accumulator (10) into electricity.

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