HEAT STORAGE SYSTEM AND METHOD FOR STORING THERMAL ENERGY

Description

[0001] The present invention relates to a heat storage system for storing thermal energy. Furthermore, the present invention relates to a method for storing thermal energy using a heat storage system.

[0002] Heat storage systems for storing thermal energy are known. These systems involve a storage material, such as water or concrete, experiencing a temperature increase through the addition of heat for thermal loading. For thermal discharging, the stored heat is released, causing the temperature of the storage material to decrease. Such sensible heat storage systems have a limited energy storage density.

[0003] Generic heat storage devices are known, for example, from DE 10 2019 210 703 A1, DE 10 2014 103 108 A1, US 4 286 141 A, and DE 203 02 591 U1. Document DE 10 2019 210 703 A1 discloses a heat storage system according to the preamble of claim 1.

[0004] The present invention is based on the object of providing a heat storage system which has an increased energy storage density and can be used flexibly.

[0005] This object is achieved according to the invention by a heat storage system comprising a storage container for receiving storage material in an interior of the storage container and a circuit for removing and supplying the storage material received in the interior, wherein the circuit comprises a heat transfer device for thermally discharging and / or thermally charging the storage material, a removal device which is configured to remove storage material in the liquid phase from the storage container and to supply it to the heat transfer device for thermally discharging and / or thermally charging, a supply channel / discharge channel which forms a fluid connection between the heat transfer device and the storage container, and a return device which is configured to return storage material in the solid phase to the interior of the storage container.

[0006] Such a heat storage system can achieve a high energy storage density, since the storage material can store and release large amounts of heat by utilizing the phase change between solid phase and liquid phase.

[0007] For both thermal discharging and thermal charging, the storage material is removed from the storage tank in the liquid phase. Thermally discharged storage material is returned to the storage tank in the solid phase. This allows for a high energy storage density, simple operation of the heat storage system, and flexible deployment.

[0008] Depending on the application area of ​​the heat storage system, the storage material can be selected for a low-temperature range or for a high-temperature range.

[0009] The heat storage system can be designed as a short-term heat storage system or as a long-term heat storage system.

[0010] In a further development of the heat storage system, the heat transfer device can be configured to transfer latent heat for thermally discharging the storage material and to transfer sensible heat for thermally charging the storage material.

[0011] By transferring latent heat to thermally discharge the storage material, a large amount of heat can be released through the phase change in a relatively small temperature range.

[0012] Advantageously, a temperature range of the heat storage system can be provided from a temperature level slightly below the decomposition temperature and / or evaporation temperature of the storage material to below the melting temperature.

[0013] In this way, it is possible to utilize both the sensible heat stored in the storage material in the liquid phase above the melting temperature and the latent heat released by the phase change.

[0014] The heat storage system can therefore achieve a particularly high energy storage density.

[0015] A further embodiment of the method can provide that the heat transfer device comprises a latent heat exchanger or is designed as a latent heat exchanger and has a discharge device for discharging solidified storage material and / or feeding it to the return device.

[0016] Preferably, the latent heat exchanger is designed as an active or driven latent heat exchanger.

[0017] The latent heat exchanger may comprise a discharge device designed to crush and / or discharge the storage material solidified by the phase change.

[0018] The discharge device can, for example, be designed as a scraping device which scrapes off and / or crushes storage material that has solidified on the latent heat exchanger.

[0019] Preferably, the storage material is discharged from the heat transfer device in solid form, in particular in granular or lumpy form.

[0020] In an advantageous embodiment of the method, the heat transfer device can comprise a rotating drum heat exchanger or be designed as a rotating drum heat exchanger.

[0021] Such a drum heat exchanger enables the transfer of latent heat. The rotating drum heat exchanger allows the storage material, which has solidified due to the transfer of latent heat, to be broken down into granular or lumpy pieces.

[0022] One embodiment of the heat storage system may provide that the return device has at least one conveying unit and / or a gravity feed and opens into the interior of the storage container.

[0023] The return device allows solidified storage material to be returned from the heat transfer device back into the interior of the storage tank.

[0024] Preferably, the solidified storage material can be returned to the interior of the storage container by the conveying unit through a conveying movement.

[0025] Gravity feeding allows the solidified storage material to be returned under the influence of gravity.

[0026] Advantageously, the solidified storage material can be returned to the storage container by gravity feed from above or from the side.

[0027] Preferably, the gravity feed may be designed as a downpipe or a separate return area.

[0028] In one embodiment, the conveying unit and the gravity feed can be combined and form a continuous conveying path for returning the solidified storage material to the interior of the storage container.

[0029] Preferably, the heat storage system can be provided with at least one conveying unit comprising a continuous conveyor, a lock and / or the like.

[0030] Preferably, the continuous conveyor can be designed as a screw conveyor, a conveyor belt, a rotary valve or the like.

[0031] The conveying unit can provide a continuous and / or discontinuous supply of the solidified storage material into the interior of the storage container.

[0032] In a further development of the heat storage system, a distribution device can be provided in the interior of the storage container in order to form a uniform distribution of storage material in the solid phase in a lower region in the interior of the storage container.

[0033] The distribution device can be designed as an active, e.g. driven, distribution device or as a passive distribution device.

[0034] Preferably, the distribution device can be designed as a slide device, a conveyor device, a guide device, for example in the form of guide plates arranged in the interior of the storage container, or the like.

[0035] In a particularly preferred embodiment of the heat storage system, at least one collection area for collecting storage material in the liquid phase can be provided in the interior of the storage container, wherein the collection area is delimited from the remaining interior of the storage container by a liquid-permeable and solid-impermeable separating device and the collection area is fluidly coupled to the removal device.

[0036] The separating device is preferably designed as a perforated plate or a sieve.

[0037] Such a separation device prevents the solid-phase storage material inside the storage container from entering the collection area. However, the liquid-phase storage material can flow through the separation device and collect in the collection area.

[0038] Due to the density difference between the storage material in the liquid phase and the storage material in the solid phase, a bed of storage material in the solid phase forms in a lower area inside the storage container. Due to the lower density of the storage material in the liquid phase, the storage material in the liquid phase collects in an upper area inside the storage container.

[0039] Since the storage material in the solid phase is returned to the interior of the storage container in granular or lumpy form, the bed of storage material in the solid phase forms a porous structure in the lower area of ​​the interior of the storage container.

[0040] Preferably, the collection area can form a lowermost area in the interior of the reservoir. The overlying bed of solid-phase storage material can form the lower area in the interior of the reservoir. The liquid-phase storage material can form an upper area in the interior of the reservoir.

[0041] When liquid-phase storage material is removed through the removal device, the liquid storage material flows through the underlying porous bed of solid-phase storage material. Due to the flow of the liquid storage material, the solid-phase storage material can be at least partially melted through heat transfer.

[0042] After flowing through the porous bed of storage material in the solid phase, the storage material in the liquid phase can preferentially collect in the collection area.

[0043] By appropriately dimensioning the hole diameter of the holes provided in the separation device, the size of particles of the storage material in the solid phase that can pass through the separation device can be influenced.

[0044] It may be advantageous for the holes in the separating device to have a hole diameter of approximately 50 mm or less, preferably approximately 20 mm or less, particularly preferably approximately 5 mm or less.

[0045] The term "approximately" means, in particular, a deviation of no more than 20%, for example no more than 10%, of the value stated.

[0046] An advantageous development of the heat storage system can provide that the at least one collection area is arranged in a bottom area of ​​the storage container and / or extends at least partially along a peripheral area of ​​the storage container.

[0047] Preferably, the collection area with the separating device can form a floor in the interior of the storage container.

[0048] Preferably, the collection area may form a lowest demarcated area in the interior of the storage container.

[0049] It can be provided that the collection area formed in the bottom area of ​​the storage container and the collection area extending at least partially along a peripheral area of ​​the storage container are fluidly coupled.

[0050] A further advantageous embodiment of the heat storage system can provide that the at least one collecting area comprises a collecting channel which extends in the interior of the storage container.

[0051] Preferably, the at least one collecting channel extends in a substantially vertical direction in the interior of the storage container.

[0052] The at least one collecting channel can be formed, for example, by a tubular element that extends into the interior of the storage container.

[0053] Preferably, a wall of the collecting channel forms the separating device.

[0054] The collecting channel can be fluidly coupled to the removal device in a lower region of the interior of the storage container.

[0055] Likewise, the collecting channel can open into the previously described collecting area, which is formed in the bottom area or in the peripheral area of ​​the storage tank.

[0056] In a preferred development of the heat storage system, the collecting channel can have a level control device which blocks a flow path formed by the collecting channel to the removal device depending on a stratification temperature of the storage material.

[0057] Preferably, the level control device has a height adjustment element which is guided in the collecting channel so as to be height adjustable along a height adjustment direction.

[0058] The height adjustment element can block a flow path between the collection region and the upper region of the interior of the storage container, in which storage material in the liquid phase is present at a relatively higher temperature level, depending on a stratification temperature of the storage material.

[0059] A height position of the height adjustment element can be regulated in particular depending on the stratification temperature of the storage material.

[0060] Particularly preferably, the height position of the height adjustment element is controlled in such a way that the height adjustment element is arranged substantially continuously at the level of the boundary between the solid phase and the liquid phase of the storage material.

[0061] In this way, when removing liquid storage material for thermal loading, it can be prevented that liquid storage material is removed at a high temperature level from the upper area of ​​the interior of the storage container by the removal device.

[0062] When removing storage material in the liquid phase, this can be achieved by having liquid storage material at a relatively lower temperature level in the region of the boundary between the solid phase and the liquid phase first flow at least partially through the porous bed of storage material in the solid phase and then collect in at least one collecting channel.

[0063] By flowing liquid storage material through at least some of the porous bed of storage material in the solid phase, the solid storage material is at least partially melted.

[0064] A design of the heat storage system can also provide that the separating device and / or the collecting area is heated at least in some areas.

[0065] Preferably, the separating device and / or the collection area can be heated by an electric heater.

[0066] Heating the separator and / or the collection area can prevent the collection area from becoming blocked due to storage material in the solid phase.

[0067] In a further embodiment of the heat storage system, a heat exchanger can be provided in a lower area in the interior of the storage tank.

[0068] Such a heat exchanger can introduce heat into the storage container in order to melt storage material in the solid phase in the lower area of ​​the interior.

[0069] Due to the isothermal phase change temperature of the storage material, the heating of the storage material in the solid phase by the heat exchanger can take place at the lowest temperature level in the storage tank.

[0070] Furthermore, the present invention is based on the object of providing a method for storing thermal energy, by means of which thermal energy can be stored with a high energy storage density and which can be used flexibly.

[0071] This object is achieved according to the invention by a method for storing thermal energy by means of a heat storage system, in particular a heat storage system according to one of the previously described embodiments, wherein, for thermal discharging, storage material in the liquid phase is removed from a storage container and is fed to a heat transfer device via a feed channel / discharge channel, the storage material is thermally discharged in the heat transfer device by transferring latent heat, the solidified storage material is fed to a return device after the thermal discharging, and the storage material in the solid phase is returned to the interior of the storage container by the return device.

[0072] This process can make it possible to achieve a high energy storage density when storing thermal energy, since the storage material can release a large amount of heat by exploiting the phase change from the liquid phase to the solid phase during thermal discharge, i.e. the transfer of latent heat.

[0073] By removing the storage material from the storage container in the liquid phase, the sensible heat stored in the storage material in the liquid phase can be utilized above the melting temperature. This process can thus further increase the energy storage density.

[0074] The method can be designed to store thermal energy in the low-temperature range or in the high-temperature range.

[0075] A preferred development of the method can provide that, for the thermal loading of the heat storage system, storage material in the liquid phase is removed from the storage container and fed to the heat transfer device, the storage material is heated by supplying heat in the heat transfer device and the heated storage material is returned to the storage container.

[0076] The thermal loading of the storage material in the heat transfer device can be provided, for example, by a heat exchanger or a heating device, for example an electric heater.

[0077] Further preferred features and / or advantages of the invention are the subject of the following description and the drawings of exemplary embodiments.

[0078] The figures show: Fig. 1 is a schematic representation of a first embodiment of a heat storage system during a thermal loading process; Fig. 2 is a schematic representation of the heat storage system in Fig. 1 during a thermal discharge process; Fig. 3 a schematic representation of an alternative embodiment of the heat storage system during a thermal charging process; Fig. 4 a schematic representation of the heat storage system in Fig. 3 during a thermal discharge process.

[0079] Identical or functionally equivalent elements are provided with the same reference numerals in all figures.

[0080] The Fig. 1 and Fig. 2 show schematically a first embodiment of a heat storage system designated as a whole by 100.

[0081] This shows Fig. 1 the heat storage system during a thermal loading process and Fig. 2 the heat storage system during a thermal discharge process.

[0082] Such a heat storage system 100 is preferably intended for use in power plant processes, in particular solar thermal power plants, conventional power plants, storage power plants and OCR power plants, or in industrial processes, for example for storing waste heat or providing process steam.

[0083] The heat storage system 100 comprises a storage container 102 configured to receive a storage material 104. The storage material 104 is provided for charging, storing, and discharging thermal energy.

[0084] The storage container 102 forms an interior space 106 in which the storage material 104 is accommodated.

[0085] The storage material 104 is a phase change material (PCM). The storage material 104 can be any phase change material selected depending on a temperature level of a region of use of the thermal storage system 100, for example, a temperature level of a waste heat stream or the like.

[0086] The storage material 104 can be selected for both a low-temperature and a high-temperature range. The storage material 104 can be, for example, water, paraffins, salt hydrates, or metals. Furthermore, the storage material 104 can be a nitrate salt or a eutectic mixture of nitrate salts and / or other salts.

[0087] Depending on a thermal loading state, the storage material 104 in the interior 106 of the storage container 102 is present both in the liquid phase and in the solid phase.

[0088] The ratio between storage material 104 in the liquid phase and storage material 104 in the solid phase in the storage container 102 depends on the thermal loading state of the storage material 104.

[0089] The higher the thermal loading state of the storage material 104, the higher the proportion of storage material 104 in the liquid phase in the storage container 102. The lower the thermal loading state of the storage material 104, the lower the proportion of storage material 104 in the solid phase in the storage container 102.

[0090] Depending on the choice of storage material 104, due to the density difference between storage material 104 in the liquid phase and storage material 104 in the solid phase, for example, storage material 104 in the liquid phase can collect in an upper region of the interior 106 of the storage container 102, while a bed of storage material 104 in the solid phase forms in a lower region of the interior 106 of the storage container 102. When water or some aqueous media is selected as the storage material 104, this can also occur in reverse.

[0091] As explained in more detail below, the bed formed from the solid-phase storage material 104 has a porous structure. This allows the liquid-phase storage material 104 to flow through the solid-phase storage material 104.

[0092] For the removal and supply of the storage material 104 accommodated in the interior 106, the heat storage system 100 comprises a circuit 108.

[0093] The circuit 108 has a withdrawal device 110. The withdrawal device 110 forms a fluid connection between the storage tank 102 and a heat transfer device 112.

[0094] Preferably, the removal device 110 is formed by a line system.

[0095] The removal device 110 opens into the interior 106 of the storage container 102, in particular into a lower region or bottom region of the storage container 102.

[0096] The storage material 104 is removed in the liquid phase from the storage container 102 by the removal device 110 and fed to the heat transfer device 112 for thermal discharge.

[0097] In addition, the circuit 108 comprises a supply channel / discharge channel 114 which forms a fluid connection between the heat transfer device 112 and the storage container 102.

[0098] The supply channel / discharge channel 114 is coupled to the interior 106 of the storage container 102 via a supply / discharge opening. The supply / discharge opening 112 forms an access / exit to the interior 106 of the storage container 102.

[0099] Storage material 104 in the liquid phase is supplied to and removed from the storage container 102 through the supply channel / discharge channel 114.

[0100] In particular, the supply channel / discharge channel 114 opens into an upper region of the storage container 102 via the supply / discharge opening.

[0101] Preferably, the supply channel / discharge channel 114 opens into the interior 106 of the storage container 102 at a relatively higher position than the removal device 110.

[0102] For thermally discharging and charging the storage material 104, the circuit 108 comprises the heat transfer device 112.

[0103] By supplying or removing heat Q, the storage material 104 supplied to the heat transfer device 112 is thermally charged or thermally discharged. During thermal charging, the storage material 104 experiences a temperature increase; during thermal discharging, the storage material 104 experiences a temperature decrease.

[0104] For thermally loading the storage material 104, the heat transfer device 112 is configured to transfer sensible heat.

[0105] For thermal loading, storage material 104 in the liquid phase is removed from the storage container 102 by the removal device 110 at a low temperature level and fed to the heat transfer device 112. By supplying heat Q, the storage material 104 is heated to a higher temperature level in the heat transfer device 112.

[0106] During thermal charging, the storage material 104 does not undergo a phase change, i.e., it remains in the liquid phase. After heating the storage material 104 in the heat transfer device 112, the heated storage material 104 is fed to the storage container 102 via the feed / discharge channel 114.

[0107] Particularly in the upper region of the storage tank 102, a temperature stratification is formed by the addition of the heated storage material 104 in the liquid phase. The heat storage system 100 can therefore also be referred to as a thermocline storage system.

[0108] For thermally discharging the storage material 104, the heat transfer device 112 is configured to transfer latent heat. Fig. 2 shows the heat storage system 100 during thermal discharge.

[0109] The heat transfer device 112 is designed as a latent heat exchanger.

[0110] For thermal discharging, the storage material 104 is fed in the liquid phase to the heat transfer device 112 via the supply channel / discharge channel 114. During thermal discharging, the storage material 104 undergoes a phase change from the liquid phase to the solid phase, releasing latent heat Q.

[0111] The heat transfer device 112 is designed, in particular, as an active latent heat exchanger. The active latent heat exchanger may have a discharge device (not shown in detail), for example, a scraping device, for discharging storage material 104 solidified by the phase change from the heat transfer device 112.

[0112] Preferably, the heat transfer device 112 is designed as a rotating drum heat exchanger.

[0113] The solidified storage material 104 is discharged from the heat transfer device 112 as a piece or as granules. The shape of the solidified storage material 104 can vary depending on the phase-change material.

[0114] The circuit 108 comprises a return device 116. The return device 116 is configured to return the solidified storage material 104 to the interior 106 of the storage container 102 after thermal discharge by releasing latent heat in the solid phase.

[0115] The return device 116 forms a connection for returning the solidified storage material 104 from the heat transfer device 112 to the storage container 102. The return device 116 opens into the interior 106 of the storage container 102.

[0116] The return device 116 comprises a conveying unit 118 for conveying the solidified storage material 104 from the heat transfer device 112 into the interior 104 of the storage container 102.

[0117] The conveyor unit 118 is preferably designed as a continuous conveyor. Preferably, the conveyor unit 118 can be designed as a conveyor screw, as in Fig. 1shown, a conveyor belt, a rotary valve or the like.

[0118] Alternatively or additionally, the return device 116 may have a lock for supplying the solidified storage material 104 into the interior 104 of the storage container 102.

[0119] Alternatively or additionally, the return device 116 may have a gravity feed that opens into the interior 106 of the storage tank 102. This gravity feed may, for example, be designed in the form of a downpipe or a separate return area in the storage tank 102.

[0120] The solidified storage material 104 can be fed to the gravity feed, for example, from above or from the side, so that the storage material 104 is guided into the interior 106 of the storage container 102 under the influence of gravity. Optionally, for example, a screw conveyor can be provided, which is arranged entirely in the interior 106 of the storage container 102 and serves to distribute the solidified storage material 104 in the lower region of the storage container 102.

[0121] In the interior 106 of the storage container 102, a collection area 120 is formed for collecting storage material 104 in the liquid phase.

[0122] The collection area 120 is provided in a lowermost area in the interior 106 of the storage container 102.

[0123] Optionally, it can be provided that an electrical and / or thermal heating device is arranged in the collection area 120 and / or adjacent to the collection area 120. This can, in particular, ensure the presence of a liquid phase.

[0124] In an alternative or additional embodiment, the collection region 120 may extend partially along a peripheral region or a peripheral wall of the storage container 102.

[0125] The collection area 120 is separated from the remaining interior 106 of the storage container 102 by a liquid-permeable and solid-impermeable separating device 122. The separating device 122 is designed as a perforated plate or a sieve.

[0126] The separating device 122 allows storage material 104 in the liquid phase to flow into the collection area 120 and prevents the storage material 104 in the solid phase from entering the collection area 120.

[0127] The collection area 120 is fluidly coupled to the removal device 110. As a result, storage material 104 in the liquid phase can be removed from the collection area 120 by the removal device 110 and fed to the heat transfer device 112.

[0128] During thermal loading of the storage material 104, storage material 104 in the liquid phase is removed from the collection region 120 at a temperature level slightly above the melting temperature or phase change temperature.

[0129] In the upper region of the storage container 102 up to the phase boundary between the liquid phase and the solid phase of the storage material 104, a temperature gradient is established from a maximum temperature of the thermally loaded storage material 104 up to the melting temperature of the storage material 104 at the phase boundary.

[0130] In the bed of the storage material 104 in the solid phase, ie in the lower region of the storage container 102, a constant temperature is formed at the melting temperature or phase change temperature of the storage material 104.

[0131] To remove storage material 104 in the liquid phase, it is removed from the collection area 120 by the removal device 110, wherein storage material 104 in the liquid phase flows in the region of the boundary between the liquid phase and the solid phase in the flow direction S through the porous bed of storage material 104 in the solid phase into the collection area 120.

[0132] By flowing the storage material 104 in the liquid phase through the porous bed of storage material 104 in the solid phase, it is provided that the storage material 104 in the liquid phase releases heat to the storage material 104 in the solid phase and at least partially melts it.

[0133] The melting process of the storage material 104 in the solid phase can take place mainly near the phase boundary between the solid phase and the liquid phase.

[0134] By removing storage material 104 in the liquid phase, a continuous phase change of storage material 104 from the solid phase to the liquid phase is formed.

[0135] The removed storage material 104 in the liquid phase is then fed to the heat transfer device 112 and heated by supplying heat Q.

[0136] The heat Q can be supplied by a heat exchanger, for example, powered by waste heat, or by a heating device, for example, an electric heater. Furthermore, the heat Q can be supplied by a high-temperature heat pump.

[0137] Preferably, the storage material 104 is heated to a temperature level significantly above the phase change temperature.

[0138] Particularly preferably, the storage material 104 is heated to a temperature level slightly below the decomposition temperature of the storage material 104.

[0139] The heated storage material 104 in the liquid phase is then fed back into the interior 106 of the storage container 102 via the feed channel / discharge channel 114.

[0140] Fig. 2 shows a thermal discharge process through the heat storage system 100.

[0141] To discharge the heated storage material 104, the storage material 104 in the liquid phase is removed from the upper region in the interior 106 of the storage container 102 via the feed channel / discharge channel 114 and fed to the heat transfer device 112.

[0142] When the storage material 104 is discharged, it is cooled in the heat transfer device 112, releasing heat Q.

[0143] In particular, the thermal discharge of the storage material 104 in the active latent heat exchanger takes place with the release of sensible and latent heat Q. The storage material 104 solidifies due to the phase change from the liquid phase to the solid phase.

[0144] After the transfer of latent heat, the solidified storage material 104 is present in lumps or in the form of loose granules due to the active latent heat exchanger, for example due to the discharge device, a scraping device or the rotating drum heat exchanger.

[0145] This lumpy or granular solidified storage material 104 is subsequently fed to the return device 116, which returns the solidified storage material 104 through the conveyor unit 118 into the interior 106 of the storage container 102.

[0146] Preferably, the solidified storage material 104 is returned by the return device 116 into the lower region of the interior 106 of the storage container 102.

[0147] By returning the solidified storage material 104 into the interior 106 of the storage container 102, the porous bed of storage material 104 is formed in the solid phase.

[0148] In the manner described above, the returned solidified storage material 104 is remelted by flowing through it with storage material 104 in the liquid phase.

[0149] In the Fig. 3 and Fig. 4 an alternative embodiment of the heat storage system 100 is shown, wherein Fig. 3 shows the heat storage system 100 during a thermal loading process and Fig. 4 the heat storage system 100 during a thermal discharge process.

[0150] This alternative embodiment of the heat storage system 100 differs from the previously described first embodiment essentially in the design of the collection area 120. The underlying process concept of thermal discharging and charging corresponds to that of the first embodiment of the heat storage system 100.

[0151] In the heat storage system 100 according to the Figs. 3 and 4 the collecting area 120 is formed by a collecting channel 124.

[0152] The collection area 120 can be formed by one collection channel 124 or by several collection channels 124 that are distributed in the interior 106 of the storage container 102.

[0153] The collection channel 124 extends in a substantially vertical direction within the interior 106 of the storage container 102. Preferably, the collection channel 124 extends continuously from a bottom of the storage container 102 to a lid of the storage container 102.

[0154] The collecting channel 124 can be formed, for example, by a tubular element.

[0155] A wall of the collection channel 124 forms the liquid-permeable and solid-impermeable separating device 122 for separating the collection area 120 from the remaining interior 106 of the storage container 102.

[0156] The separating device 122 can, for example, be formed by a plurality of passages or holes along a longitudinal extent in the wall of the collecting channel 124. Likewise, the separating device 122 can be formed by a tubular sieve.

[0157] A lowermost section of the collecting channel 124 is fluidly connected to the removal device 110 so that storage material 104 in the liquid phase can be supplied to the heat transfer device 112 for thermal charging.

[0158] In order to prevent storage material 104 in the liquid phase from being removed at a high temperature level from the uppermost region of the interior space 106 through the collecting channel 124 extending in the interior space 106 during thermal loading, the collecting channel 124 has a level control device 126.

[0159] The level control device 126 blocks a flow path formed by the collecting channel 124 to the removal device 110 depending on the stratification temperature of the storage material 104. This prevents the storage material 104 in the liquid phase from flowing at a high temperature level from the uppermost region of the interior space 106 through the collecting channel 124.

[0160] The level control device 126 comprises a height adjustment element 128 which is arranged within the collecting channel 124 so as to be height adjustable along a height adjustment direction H and blocks the flow path.

[0161] The height adjustment element 128 can be actively driven in order to be arranged in a corresponding height position depending on the stratification temperature of the storage material 104.

[0162] In particular, it is provided that the height adjustment element 128 is constantly arranged substantially at the level of the boundary between the solid phase and the liquid phase of the storage material 104.

[0163] Likewise, the height adjustment element 128 can be designed as a passive element which automatically arranges itself in the corresponding height position as a function of the stratification temperature of the storage material 104 by a change in density or the like.

[0164] In an alternative embodiment of the level control device 126, the collecting channel 124 can be designed to be height-adjustable. An upper end of the collecting channel 124 can be arranged at different height positions in the interior 106 of the storage container 102 in the height adjustment direction H in order to prevent the storage material 104 in the liquid phase from flowing at the high temperature level from the uppermost region of the interior 106 through the collecting channel 124.

[0165] The height adjustment can be achieved by means of telescopic tubes inserted into one another or by means of two twisting coaxial tubes.

[0166] When removing storage material 104 in the liquid phase, the level control device 126 ensures that liquid storage material 104 in the region of the boundary between the solid phase and the liquid phase, ie at a relatively lower temperature level, first flows through an upper region of the porous bed of storage material in the solid phase and then collects in the collecting channel 124.

[0167] By flowing through the porous bed of storage material 104 in the solid phase with the storage material 104 in the liquid phase in certain areas, the storage material 104 in the solid phase is at least partially melted.

[0168] The Fig. 4 The thermal discharge process of the heat storage system 100 shown takes place in the same way as the one described above according to Fig. 2 described discharge process. List of reference symbols

[0169] 100Heat storage system 102Storage tank 104Storage material 106Interior 108Circuit 110Withdrawal device 112Heat transfer device 114Supply channel / discharge channel 116Recirculation device 118Conveyor unit 120Collection area 122Separation device 124Collection channel 126Level control device 128Height adjustment element QHeat

Claims

1. Heat storage system (100) comprising a storage container (102) for receiving storage material (104) in an interior (106) of the storage container (102) and a circuit (108) for removing and supplying the storage material (104) received in the interior (106), wherein the circuit (108) comprises: - a heat transfer device (112) for thermally discharging and / or thermally charging the storage material (104), - a removal device (110) which is set up to remove storage material (104) in the liquid phase from the storage container (102) and to feed it to the heat transfer device (112) for thermal discharging and / or thermal charging, - a supply channel / discharge channel (114) forming a fluid connection between the heat transfer device (112) and the storage container (102), and characterized in that the circuit (108) comprises a return device (116) which is set up to return storage material (104) in the solid phase to the interior (106) of the storage container (102).

2. Heat storage system according to Claim 1, characterized in that the heat transfer device (112) is set up to transfer latent heat for thermally discharging the storage material (104) and to transfer sensible heat for thermally charging the storage material (104).

3. Heat storage system according to Claim 1 or 2, characterized in that the heat transfer device (112) comprises a latent heat exchanger or is designed as a latent heat exchanger and has a discharge device for discharging solidified storage material and / or feeding it to the return device (116).

4. Heat storage system according to one of the preceding claims, characterized in that the heat transfer device (112) comprises a rotating drum heat exchanger or is designed as a rotating drum heat exchanger.

5. Heat storage system according to one of the preceding claims, characterized in that the return device (116) has at least one conveying unit (118) and / or a gravity feed and leads into the interior (106) of the storage container (102).

6. Heat storage system according to Claim 5, characterized in that the at least one conveying unit (118) has a continuous conveyor, a sluice and / or the like.

7. Heat storage system according to one of the preceding claims, characterized in that a distribution device is provided in the interior (106) of the storage container (102) in order to form a uniform distribution of storage material (104) in the solid phase in a lower region in the interior (106) of the storage container (102).

8. Heat storage system according to one of the preceding claims, characterized in that at least one collection region (120) for collecting storage material (104) in the liquid phase is provided in the interior (106) of the storage container (102), wherein the collection region (120) is delimited from the rest of the interior (106) of the storage container (102) by a liquid-permeable and solid-impermeable separating device (122) and the collection region (120) is fluid-coupled to the removal device (110).

9. Heat storage system according to Claim 8, characterized in that the at least one collection region (120) is arranged in a base region of the storage container (102) and / or extends at least in some regions along a peripheral region of the storage container (102).

10. Heat storage system according to Claim 8 or 9, characterized in that the at least one collection region (120) comprises a collection channel (124) which extends in the interior (106) of the storage container (102), preferably in a substantially vertical direction.

11. Heat storage system according to Claim 10, characterized in that the collection channel (124) has a level regulating device (126) which blocks a flow path formed by the collection channel (124) to the removal device (110) depending on a stratification temperature of the storage material (104).

12. Heat storage system according to one of Claims 8 to 11, characterized in that the separating device (122) and / or the collection region (120) is heated at least in some regions.

13. Heat store according to one of the preceding claims, characterized in that a heat exchanger is provided in a lower region in the interior (106) of the storage container (102).

14. Method for storing thermal energy by means of a heat storage system (100), in particular a heat storage system (100) according to one of Claims 1 to 13, comprising the steps that - for thermal discharging, storage material (104) is removed from a storage container (102) in the liquid phase and fed to a heat transfer device (112) via a supply channel / discharge channel (114), - the storage material (104) is thermally discharged in the heat transfer device (112) by transferring latent heat, characterized in that - solidified storage material (104) is fed to a return device (116) after thermal discharge, and - the storage material (104) in the solid phase is returned through the return device (116) into the interior (106) of the storage container (102).

15. Method according to Claim 14, characterized in that, for thermally charging the heat storage system (100), storage material (104) is removed from the storage container (102) in the liquid phase and fed to the heat transfer device (112), the storage material (104) is heated by supplying heat in the heat transfer device (112) and the heated storage material (104) is returned into the storage container (102).