WO2025228593A1 - Heat store - Google Patents

Abstract

The invention relates to a high-temperature heat store having an storage container (1) for storing thermal energy, wherein the storage container (1) has an upper container section (2) and a lower container section (3) connected to the upper container section (2), and the upper container section (2) forms an upper container closure, in particular a container dome (4), and the lower container section (3) forms a container base (6), wherein the upper container section (2) and the lower container section (3) delimit a loading space (7) for loading the storage container (1) with a heat-storage material (8). According to the invention, the carrier gas (9, 10) can be supplied to the loading chamber (7) via an annular channel (12) and/or can be discharged from the loading chamber (7) via the annular channel (12).

Description

Heat storage

The invention relates to a high-temperature thermal energy storage system with a storage tank for storing thermal energy, in particular for providing high-temperature heat for power generation and/or as process heat for industrial plants and processes, further in particular with a storage capacity of greater than 50 MWh, preferably greater than 100 MWh, and a heat resistance of the storage tank of 1000 °C to 1500 °C, preferably 1100 °C to 1300 °C, wherein the storage tank has an upper tank section and a lower tank section connected to the upper tank section, and the upper tank section forms an upper tank closure, in particular a tank dome, and the lower tank section a tank bottom, wherein the upper tank section and the lower tank section define a charging chamber for charging the storage tank with a heat-storing material, wherein during a charging cycle, a charge of the heat-storing material introduced into the storage tank is transferred by a hot carrier gas, in particular hot air, when the storage tank is set up as intended. is permeable in a vertical direction to charge the heat-storing material by heat transfer from the hot carrier gas to the heat-storing material, wherein during a discharge cycle the supply of a colder carrier gas, in particular cold air, is permeable in a vertical direction when the storage container is set up as intended, in order to discharge the heat-storing material by heat transfer from the heat-storing material to the colder carrier gas and to heat the carrier gas, and wherein the heat-storing material does not undergo a phase change during the charging cycle and during the discharge cycle.

Furthermore, the present invention relates to a method for operating a high-temperature heat storage device of the aforementioned type with a storage container for storing thermal energy, wherein the storage container has a charge of a heat-storing material, wherein during a charging cycle of the storage container, the charge is supplied with a hot carrier gas, in particular hot air, in a vertical direction in order to charge the heat-storing material by heat transfer from the hot carrier gas to the heat-storing material, and wherein during a discharging cycle, the charge is supplied with a colder carrier gas, in particular cold air, in a vertical direction direction through which the heat-storing material is discharged by heat transfer from the heat-storing material to the colder carrier gas and heats up the carrier gas, and wherein the heat-storing material does not undergo a phase change during the charging cycle and during the discharging cycle.

The invention relates to so-called "sensible" heat storage devices, which change their "sensible" temperature during the charging and discharging process. Since this type of heat storage device does not undergo phase transitions, it can be used over a wide temperature range, particularly in the high-temperature range.

High-temperature thermal energy storage systems can be used to store large amounts of thermal energy at temperatures exceeding 1000 °C. Waste heat from industrial or power plant processes is often generated intermittently rather than continuously. Energy-intensive industries, in particular, produce significant amounts of waste heat at high temperatures, which can be converted into process heat or electricity using thermal energy storage systems. The heat generated by the storage system can be used, for example, for targeted process recirculation or power generation. When storing thermal energy from industrial processes, thermal energy storage systems can improve efficiency and stabilize the process conditions of high-temperature industrial processes. Such thermal storage systems can also be used to provide industrial process heat from electricity. During periods of overproduction from renewable energy sources, electricity is converted into high-temperature heat, which is then stored and later supplied to industrial consumers as process heat. In gas and steam turbine power plants, such thermal storage systems can be used to decouple electricity and heat generation over time, allowing excess heat to be temporarily stored in the thermal storage unit. To utilize the stored heat in a power plant process, heat from a hot carrier gas, particularly hot air, generated during the discharge of a high-temperature storage unit can be transferred to a working fluid of the power plant process, especially a working fluid of a steam power process. In a steam power process, the heat from the carrier gas can be used for steam generation, feedwater preheating, and/or steam superheating. However, it is also fundamentally possible to use the heat transferred to the carrier gas in the form of... To supply hot air to the combustion chamber of a conventional coal-fired power plant and/or a combined cycle power plant in order to burn a fuel such as coal or gas.

A thermoelectric storage power plant, for example, can include a compressor for compressing the carrier gas, at least one gas heater for heating the carrier gas, multiple high-temperature storage tanks for storing the heat from the heated carrier gas, and at least one heat exchanger, such as a steam generator, for transferring the heat from the heated carrier gas to a working fluid of a power plant process. If the carrier gas is heated in the gas heater by converting electrical energy into thermal energy, and the gas heater can have at least one electrical heating element for this purpose, electrical energy can be stored as heat during a charging cycle when electricity generation is high and demand is low. During peak loads, at least one thermal storage tank is discharged in at least one discharge cycle, and the resulting hot carrier gas is used for electricity generation, for example, to vaporize water for a steam power process. The generated electrical energy can then be fed back into a power grid. In this way, electrical power can be provided flexibly, quickly, and cost-effectively during short-term peak loads.

Electricity generation from renewable energy sources can be subject to fluctuations on different timescales, ranging from seasonal variations throughout the day to short-term fluctuations. Such fluctuations amplify the fluctuations in electricity demand and increase the need for balancing peak loads. High-temperature thermal energy storage systems can convert excess solar or wind power into heat and store it temporarily. The stored thermal energy can then be converted back into electricity when demand is correspondingly higher.

The object of the present invention is to provide a high-temperature heat storage device and a method for storing high-temperature heat in a high-temperature heat storage device of the type mentioned above, in particular for storing excess thermal energy generated from the conversion of surplus electrical energy from conventional or renewable electricity generation into heat and/or for Storage of excess thermal energy from industrial or power plant processes and/or for the time-delayed provision of high-temperature heat for power generation and/or as process heat for industrial plants and processes as well as power plant plants, wherein the high-temperature heat storage system enables the storage of thermal energy at temperatures above 1000 °C, preferably at 1300 °C or more, and the provision of high-temperature heat in a process-engineering and structurally simple manner with low manufacturing, operating and maintenance costs of the heat storage system.

In particular, it is an object of the present invention to provide a high-temperature heat storage device which is characterized by a uniform flow around the heat-storing material in the storage container during charging and/or discharging at a low flow velocity and thus achieves an efficient thermal exchange between the carrier gas and the heat storage material.

Another object of the present invention is the provision of a high-temperature heat storage system with improved mechanical and thermal strength.

Finally, the high-temperature heat storage system according to the invention should be characterized by a high efficiency, defined as the ratio of usable thermal energy to the energy used for charging the storage system, with energy losses being low due to improved storage insulation.

Further advantageous features of the thermal storage device according to the invention are said to be a high storage capacity, short charging and discharging times, and a high number of possible storage cycles, wherein the storage capacity is defined as the maximum amount of heat that can be absorbed by the storage device. Factors influencing the storage capacity of thermal storage devices are the storage volume, the specific heat capacity of the storage medium, and the temperature difference. A high storage capacity can only be achieved if homogeneous flow conditions exist within the storage device. The temperature limit for loading the heat-storing material by coming into contact with the hot carrier gas should be above 1000 °C, up to 1500 °C, preferably between 1100 °C and 1300 °C.

The aforementioned problems are solved by a high-temperature heat storage device with the features of claim 1 and by a method for storing high-temperature heat in a high-temperature heat storage device with the features of claim 10. Advantageous embodiments of the invention are the subject of the dependent claims.

According to the invention, to solve the aforementioned problems, a supply and/or discharge of carrier gas into and/or out of the storage container is provided via an annular channel during the charging cycle and/or during the discharging cycle. The annular channel enables a uniform distribution of the carrier gas and a uniform flow of the charge, in particular in the form of a packed bed, of a thermally conductive material introduced into the charging chamber at a low flow velocity. This ensures efficient thermal exchange between the carrier gas and the heat-storing material and minimizes the formation of dead zones in the packed bed that do not participate in heat transfer. Dead zones in the heat storage system, where the heat storage material is not or not homogeneously surrounded by the carrier gas, lead to a decrease in the storage capacity, i.e., the maximum amount of heat that can be absorbed by or released from the storage system.

At the same time, a suitable design of the annular channel and the gas transition between the annular channel and the feed chamber allows the flow through the heat storage material to be achieved with a low pressure loss.

The invention relates to a sensible heat storage device, wherein the heat storage material does not change its state of matter during charging or discharging, but rather heats up and cools down depending on whether the heat storage device is being charged or discharged. Sensible heat storage devices have the advantage of a simple design and are inexpensive to manufacture on an industrial scale, particularly when the heat storage material is a readily available, inexpensive bulk material with high heat capacity. The annular channel has at least one opening for supplying carrier gas into the annular channel and/or for discharging carrier gas from the annular channel, and at least one gas passage for the transfer of carrier gas between the annular channel and the charging chamber. Preferably, the annular channel is located adjacent to the bottom of the storage container in the lower region.

The storage container may have at least one opening in the upper area adjacent to the upper container end for supplying carrier gas into the charging chamber or for draining carrier gas from the charging chamber.

Preferably, hot carrier gas is supplied to the annular channel in the lower region of the storage tank, from where it passes through the gas passage into the charging chamber. The hot carrier gas then flows vertically upwards along the charging channel of the storage tank containing the heat-storing material and exits the tank through the opening in the upper region. Heat transfer from the hot carrier gas to the heat-storing material causes the storage tank to be charged. During discharge, cooler carrier gas is supplied to the charging channel, particularly through the opening in the upper region of the storage tank. This cooler carrier gas flows downwards along the charging channel and is heated by heat transfer from the heat-storing material. The heated carrier gas can then pass from the charging chamber into the annular channel near the bottom of the storage tank via the gas passage and is then discharged from the annular channel and thus from the storage tank via the channel opening of the annular channel or another channel opening. However, a flow of the cooler carrier gas from bottom to top within the storage tank is not excluded.

Particularly preferably, the supply and discharge of the carrier gas during the loading cycle and during the unloading cycle takes place via only one channel opening in the ring channel and only one container opening in the storage container.

The heat storage device according to the invention is designed for vertical operation, so that the heat storage device is vertical with respect to the longitudinal axis of the storage container during the charging cycle and during the discharging cycle. It is arranged in an upright position. During both loading and unloading, the storage container is subjected to a vertical flow of heat for heat transfer.

A particularly preferred design embodiment of the heat storage device according to the invention provides that the lower container section is arranged concentrically to the upper container section, wherein the lower container section has a larger internal cross-sectional area than the upper container section and the upper container section partially dips into the lower container section at its bottom.

The filling chamber can be formed by an upper filling zone and a lower filling zone. The upper filling zone can be bounded transversely to the orientation of the storage container, particularly radially outwards, by the upper container section, and the lower filling zone can be bounded transversely to the orientation of the storage container, particularly radially outwards, by the lower container section, wherein, preferably, the lower filling zone extends transversely to the orientation of the storage container, particularly in a radial direction, beyond the upper filling zone. The aforementioned embodiment of the invention enables a simple structural design of the storage container according to the invention and a homogeneous flow of the carrier gas, particularly in conjunction with the annular channel according to the invention for supplying or discharging the carrier gas to or from the filling chamber. The lower feeding zone, extending radially outwards beyond the upper feeding zone, allows for a structurally simple design of the gas transfer between the annular channel and the second feeding zone. The upper and lower container sections preferably have cylindrical walls that define the feeding zones.

The annular channel is preferably arranged concentrically to the filling chamber, and particularly concentrically to the upper container section. Most preferably, the annular channel extends circumferentially along the entire circumference of the upper container section. Most preferably, the annular channel is formed on the outside of a side wall of the upper container section, with the side wall defining the upper filling zone. Preferably, the energy storage device has a cylindrical structure, with both the upper and lower container sections being cylindrical. The lower container section can then have a cylindrical side wall that concentrically surrounds a cylindrical side wall of the upper container section in the lower, near-edge region of the upper container section. The annular channel can then be formed between the side walls of the two container sections.

The embodiments described below refer to the preferred cylindrical design of the storage container with container sections having cylindrical container or side walls. It is understood that corresponding designs can also be provided for and implemented in storage containers with a polygonal cross-sectional geometry, even if this is not explicitly described below.

The annular channel can be formed between two concentric side walls of the upper and lower container sections, in particular wherein the annular channel is bounded by an outer surface of a side wall of the upper container section and an inner surface of a side wall of the lower container section arranged concentrically to the side wall of the upper container section, and/or wherein the annular channel is formed at the lower end of the upper container section, adjacent to the container bottom. When the heat storage unit is installed vertically on a surface as intended, the annular channel is bounded by vertical wall sections of the container sections transversely to the longitudinal axis of the storage container or in a radial direction.

Preferably, the annular channel extends vertically to a lower edge of the side wall of the upper container section and is bounded radially outwards by a vertical side wall of the lower container section. The annular channel can be terminated at the top by an inclined side wall of the lower container section, through which the upper and lower container sections are connected. The annular channel can be closed laterally and at the top, except for the at least one channel opening provided for the supply and/or discharge of carrier gas. A practical design for the storage container, which is simple and inexpensive to manufacture and is characterized by high mechanical strength of the construction, provides that at the bottom end of the upper container section a wall section of the upper container section is designed as a hanging wall section.

A hanging wall section at the lower end of the upper container section allows the lower area of the storage container's filling chamber, which is bordered by the upper container section, to be separated from the ring channel, at least partially.

Below the hanging wall section, however, the loading chamber is open in a radial direction towards the ring channel.

The hanging wall section preferably does not rest against the lower container section at its bottom. In the area below the connection point between the upper and lower container sections, the upper container section is then freely suspended and preferably supported and stabilized only at the connection point to the lower container section. The annular space formed between the hanging wall of the upper container section and an outer wall of the lower container section can then form at least part of the annular channel.

Furthermore, the hanging wall section towards the loading chamber and towards the ring channel can each be thermally insulated to ensure high temperature resistance of the storage tank in this area.

The upper and lower container sections can be made of metal components, each preferably having an outer metallic container wall, in particular made of steel. Preferably radially internal, but optionally also radially external, fire-resistant insulation can be provided on the container wall.

The insulation of the container wall can be multi-layered. In particular, the insulation can be formed by an outer insulating layer facing the filling chamber, made of an insulating material with high hardness. for example in the form of a lining with refractory brick, and an inner insulating layer of lower hardness arranged between the metallic container wall and the outer insulating layer, which may be formed, for example, by a cement-containing insulating material.

The suspended wall section at the lower end of the upper container section can have a cylindrical metal component as a support element, in particular a cylindrical steel component, which can have fire-resistant insulation, in particular having a multi-layer structure, and more preferably a two-layer structure, radially inside on the side facing the filling chamber and, preferably, radially outside on the side facing the annular channel. The support element increases the stiffness of the upper container section. This contributes to the high stability of the storage container.

Preferably, the support element can be embedded on both sides in a thermal insulation layer made of a less hard insulating material, for example, a cementitious insulating material, wherein an outer insulation layer made of a more hard insulating material, for example, in the form of a lining of refractory brick, can adjoin the inner insulation layer thus formed. The outer insulation layer can then directly adjoin the loading chamber (radially inner) and the annular channel (radially outer).

The support element of the hanging wall section in the area of the connection point between the upper container section and the lower container section can particularly preferably be connected, in particular welded, to a metallic side wall of the upper container section.

To ensure high resistance of the structure, a cooling device can be provided for cooling the suspended wall section, in particular for cooling the support element. The cooling can be achieved via cooling coils running concentrically around the support element, preferably using water cooling.

Alternatively, the upper container section can rest on the lower container section at ground level. A support structure can be provided, which supports the upper container section on the lower container section. Openings with a clear diameter several times the particle diameter can be provided in the support structure, allowing the heat-storing material to pass from the feed chamber or feed zone into the annular channel. The support structure serves to absorb the weight of the upper container section and is subject to compression. Therefore, it is not necessary to integrate a metallic support into the structure. Cooling of the support structure is then unnecessary.

The supporting structure can have several, preferably ring-shaped, column-like structural sections, between which openings are formed for the transfer of the heat storage material from the feed chamber into the annular channel. Adjacent structural sections can converge upwards and be connected in an arc, with an underlying opening being bridged in the area of the arc-shaped connection. An arc-shaped design allows for high compressive strength of the supporting structure.

The annular channel is preferably open towards the feed chamber, particularly towards the lower feed zone, with the opening forming the gas passage for carrier gas to the feed chamber, and particularly wherein the annular channel is closed in the radial direction towards the upper feed zone. The annular channel is also preferably closed at the top, with the exception of the at least one channel opening for the supply and/or discharge of carrier gas.

The annular channel extends vertically downwards, preferably to the lower edge of the section of the upper container designed as a hanging wall. A gas passage plane located at the lower outer edge of this section of the upper container designed as a hanging wall can functionally and structurally limit the annular channel downwards.

The bottom of the storage container can be formed by a bottom wall of the lower container section, which limits the filling space vertically downwards and extends radially preferably to below the gas passage of the annular channel. A central discharge opening for heat storage material can be provided in the floor wall.

On the inside, the lower section of the container can have a conical loading surface for the heat-storing material, which preferably extends from the discharge opening in the bottom wall to the radial outer edge of the annular channel below the channel. The desired position of the heat-storing material in the lower loading zone can shift outwards as the storage container operates, with the angle of repose, i.e., the angle between the inclined outer surface of the material and a horizontal reference plane, decreasing as the heat storage system operates. As the process increases, the material in the area below the annular channel migrates towards the gas passage of the annular channel. Eventually, the boundary of the heat-storing material can shift so far towards the annular channel that the material passes through the gas passage and enters the channel. The boundary of the material, or its outer surface, can then, at least partially, lie within the annular channel and above a gas passage plane of the annular channel located at the lower edge of the upper section of the container.

To ensure homogeneous flow through the annular channel and uniform flow of heat-storing material to the feed chamber, no retaining elements, such as heat-resistant perforated plates or bricks, are preferably provided in the area of the gas passage between the annular channel and the feed chamber. The heat-storing material is then not retained in the feed chamber and, as described above, can migrate towards the annular channel during operation of the heat storage system and eventually even rise within the annular channel or interact with it.

The gas passage of the annular channel to the feed chamber can preferably extend substantially in a ring shape over the entire circumferential length of the annular channel. In other words, the annular channel is preferably open all the way around to the feed chamber. The annular channel can have a constant opening width (clear width) of the gas passage along its circumference. This results in low flow losses and a uniform flow of gas to the heat-storing material when the carrier gas is fed into or discharged through the annular channel. Preferably, the annular channel has a constant clear width in the vertical direction from the gas passage upwards to an inclined side wall of the lower container section.

Particularly preferred is the filling of the filling chamber with a lumpy and/or spherical heat-storing material; in particular, thermal storage spheres made of aluminum oxide ceramic (Al₂O₃ ceramic) can be used as the heat-storing material. The mean material and/or sphere diameter can be between 1.0 cm and 10.0 cm, and more preferably greater than or equal to 1.5 cm and/or up to 3 cm.

The density of the heat-storing material is preferably in the range between 3000 kg/ ^m³ and 6000 kg/ ^m³ , more preferably between 3000 kg/ ^m³ and 4000 kg/ ^m³ , and more preferably at approximately 3500 kg/ ^m³ . This applies in particular to the use of spherical heat storage material made of an aluminum oxide ceramic. Such heat storage spheres are characterized by low material costs, high heat capacity and thermal conductivity, as well as high heat resistance.

The opening area of the gas passage can correspond to a multiple of the grain size, in particular the sphere diameter, of the heat-storing material used, so that the heat-storing material can pass through the gas passage of the annular channel during the operational displacement of the packing in a radial direction to the annular channel.

Preferably, the storage tank is operated as a fixed-bed storage tank below the fluidization limit of the packed bed.

Particularly preferred is a flow through the heat-storing material in the region of the gas passage of the annular channel at a carrier gas velocity below the minimum fluidization velocity, especially wherein the carrier gas velocity can be less than 80%, preferably less than 50%, and further preferably less than 25%, of the minimum fluidization velocity. This reliably prevents fluidization of the packed bed when flowing through the heat-storing material in the region of the annular channel. The minimum fluidization velocity, as the lower limit for the existence of a fluidized bed, can be calculated, for example, using the Ergun equation, which exhibits a small deviation between measured and calculated values. The calculation of the minimum fluidization velocity can be found, for example, in the publication by Werther J.: Flow-mechanical fundamentals of fluidized beds, Chem.-Ing.-Tech. 49, No. 3, pages 193 to 202, (1977). The minimum fluidization velocity is also calculated for the maximum charging temperature of the storage tank and the absolute pressure at which charging/discharging takes place.

Preferably, the gas velocity of the carrier gas flowing through the annular channel, particularly during the discharge cycle of the heat storage system, is less than or equal to the gas velocity of the carrier gas flowing through the upper section of the storage tank, particularly during the charging cycle. The volumetric flow rate of the carrier gas is preferably selected such that both the gas velocity of the carrier gas flowing through the annular channel and the gas velocity of the carrier gas flowing through the upper section of the tank are less than the minimum fluidization velocity. This improves the heat transfer between the heat-storing material and the carrier gas and reliably prevents the discharge of portions of the heat-storing material due to fluidization of the packing material, even within the annular channel.

In the design of a heat storage device according to the invention, it is further preferably provided that the clear inner cross-sectional area of the annular channel, particularly in the area of the gas passage at the level of the gas passage plane, is greater than or equal to the clear inner cross-sectional area of the upper container section at the upper end of the charging chamber. The inner (clear) cross-sectional area of the upper container section can be between 3 ^m² and 100 ^m² , preferably between 30 ^m² and 80 ^m² .

The specific mass flow rate of the carrier gas when flowing through the feed of the heat-storing material in the storage container can be in the range between 0.5 and 6.0 kg/(s*m ² ), based on the inner cross-sectional area of the upper container section of the storage container in the area of the feed with the heat-storing material. The grain size, preferably the mean diameter, of the heat-storing material can be in the range between 10 mm and 40 mm, for example in the range of 15 mm.

The density of the heat-storing material can preferably be in the range between 3000 kg/m ³ and 6000 kg/m ³ , and more preferably in the range of approximately 3500 kg/m ³ .

Under minimal fluidization conditions, the porosity of the feed can assume values between 0.25 and 0.6, in particular 0.4.

The carrier gas is preferably supplied to the storage container at an overpressure level, wherein the storage container is designed as a pressure vessel and wherein the pressure vessel is designed for a permissible operating pressure of more than 1.5 bar (absolute), in particular more than 5 bar (absolute), further in particular more than 8 bar (absolute), preferably 9 bar (absolute), and, further preferably, for a maximum operating pressure of less than 20 bar (absolute).

Furthermore, during the charging of the storage container, a supply of hot carrier gas to the annular channel at a temperature of more than 1000 °C to 1500 °C, preferably between 1100 °C and 1300 °C, is provided. This requires a corresponding heat resistance of the heat storage device according to the invention, in particular of the storage container and all gas lines provided for the supply and discharge of hot carrier gas.

In the area of the tank dome, the maximum temperature during operation of the heat storage system can range between 20 °C and 1500 °C, for example, approximately 500 °C. Due to the supply of hot carrier gas, temperatures in the annular channel can range between 1000 °C and 1500 °C, preferably between 1100 °C and 1300 °C. The required discharge temperature for heat utilization can be at least 500 °C, preferably at least 600 °C, and up to 1500 °C, more preferably up to 800 °C. The minimum and maximum temperature values specified above refer in particular to the interconnection of multiple storage systems. A preferred design of the storage container provides that the supply of hot carrier gas into the annular channel takes place in the upper area of the annular channel, in particular directed obliquely towards the upper section of the container.

The storage tank is preferably designed as a steel structure with tank walls made of or incorporating a steel material and has at least partial fire-resistant insulation, in particular multi-layered and/or on both sides, especially in the area adjacent to the ring channel. Furthermore, insulation is specifically provided on a suspended tank wall at the bottom end of the upper tank section. The steel material can be of a grade of [grade] or a comparable grade.

For thermal insulation, insulation may be provided on a side of the upper container section and/or the lower container section facing the charging chamber and/or the annular channel, which has a multi-layer structure, in particular a two-layer structure, with at least one fire-resistant outer insulating layer made of an insulating material with a high hardness facing the charging chamber, in particular the first, upper charging zone, and with at least one further inner insulating layer with a lower hardness adjacent to the outer insulating layer.

If the storage tank has an upper section that forms a hanging wall at its lower end, the hanging wall can be insulated on both sides, on the side facing the feed zone and on the side facing the annular channel. Additionally, the hanging wall can be cooled, preferably by means of cooling pipes, cooling coils, or the like, which can be embedded in the insulating layer with lower hardness, preferably on the side of the hanging wall facing the annular channel.

The outer insulating layer can consist of a highly rigid insulating material, for example, a lining of refractory brick, such as a phosphate-bonded brick (80% alumina, fired). A cementitious insulating material can be used to form an inner insulating layer. The outer insulating layer, with its higher rigidity, provides high compressive strength against the The fill level is reached. The inner insulating layer with lower hardness, on the other hand, primarily serves to increase thermal stability.

To ensure uniform flow through the fill column in the feed chamber, the height-to-diameter ratio in the upper feed zone, which is radially bounded by a preferably cylindrical container wall of the upper container section, can be between 0.5 and 1.8, preferably between 1.0 and 1.6. The height-to-diameter ratio represents the ratio of the active fill height to the inner diameter of the upper container section that bounds the upper feed zone.

Further features, advantages, and applications of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawing and the drawing itself. All features described and/or illustrated, individually or in any combination, constitute the subject matter of the present invention, irrespective of their compilation in the claims or their cross-reference.

The drawing shows:

Fig. 1 shows a schematic longitudinal sectional view of a storage tank for a high-temperature heat storage system according to the invention;

Fig. 2 shows a schematic longitudinal sectional view of a further embodiment of a storage container for a high-temperature heat storage system according to the invention, with a higher level of detail compared to Fig. 1.

Fig. 3 shows a schematic longitudinal sectional view of a further embodiment of a storage container for a high-temperature heat storage system according to the invention.

Figures 1 and 2 schematically show possible embodiments of storage tanks 1 of a high-temperature thermal energy storage system for storing thermal energy, in particular wherein the high-temperature thermal energy storage system is designed and suitable for providing high-temperature heat for power generation and/or as process heat for industrial plants and processes or for power plant systems, further in particular wherein the storage tank has a has a storage capacity of greater than 100 MWh and is designed for feed temperatures of greater than 1000 °C to 1500 °C, preferably from 1100 °C to 1300 °C.

Components shown in Figs. 1 and 2 with matching reference numerals have the same or similar design and/or functionality, even if this is not explicitly described in detail.

The storage container 1 has an upper container section 2 and a lower container section 3. The upper container section 2 forms an upper container closure, in particular a container dome 4 with an upper side wall 5 in the form of a spherical segment. The lower container section 3 forms a container bottom 6 of the storage container 1.

The upper container section 2 and the lower container section 3 define a loading chamber 7 for filling with a heat-storing material 8. The heat-storing material 8 is shown only schematically and, in this example, consists of aluminum oxide-containing ceramic spheres with a diameter of, for example, 1.5 cm to 2 cm. The heat-storing material 8 is introduced into the loading chamber 7 as a loose fill. The terms "loading" and "fill" are used interchangeably and synonymously below. In principle, however, the storage container 1 could also be filled with a lumpy, non-spherical heat-storing material. Alternatively, the heat-storing container 1 could, in principle, also contain any heat-storing elements that are inserted into the storage container 1.

The storage container 1 is designed for vertical installation on a base and is arranged in a vertically upright position during a loading cycle and during a discharging cycle. During loading and discharging, a carrier gas 9, 10 flows essentially vertically through the storage container 1, particularly through the upper section 2.

During the loading cycle, hot carrier gas 9, in particular hot air with a temperature of, for example, 1200 °C, is supplied to the loading chamber 7. At least one electric air heater (not shown) can be provided for generating the hot air. The loading chamber 7, and thus the bulk material of the The heat-storing material 8 is permeated by a vertically rising flow of hot carrier gas 9, in order to heat the heat-storing material 8 by heat transfer from the hot carrier gas 9. Alternatively, the storage container 1 could also be configured to be permeated by a downward vertical flow of hot carrier gas 9.

During the discharge cycle, the feed chamber 7, and thus the bed of heat-storing material 8, is traversed vertically from top to bottom by a colder carrier gas 10, in particular cold air, in order to heat the colder carrier gas 10 by heat transfer from the heat-storing material 8. In principle, during discharge, the carrier gas 10 could also be guided through the storage container 1 from bottom to top.

The supply of hot carrier gas 9 into the storage container 1 during the charging cycle and the removal of carrier gas 10 heated in the storage container 1 from the storage container 1 during the discharging cycle takes place via at least one channel opening 11 of an annular channel 12.

At least one opening 13 is provided in the area of the container dome 4 to discharge the carrier gas 9 from the storage container 1 during the charging cycle after it has flowed through it. The cooler carrier gas 10 is supplied to the storage container 1 via the opening 13 in the area of the container dome 4 during discharge.

Furthermore, the storage container 1 has an upper filling opening 14 for filling the heat-storing material 8 into the interior of the storage container 1 and a discharge opening 15 in the middle in the area of the container bottom 6 in order to be able to discharge the heat-storing material 8 from the storage container 1 as required.

The annular channel 12 is bounded radially on the inside by a vertical side wall 16 of the upper container section 2 and radially on the outside by a vertical side wall 17 of the lower container section 3. The side walls 16, 17 preferably form the outer walls of the storage container. The side walls 16, 17 can, as shown in greater detail in Fig. 2, have an internal multi-layered insulation, which is not shown in Fig. 1. The side walls 16, 17 are preferably made of a metallic material, in particular steel. The connection of the upper container section 3 to the lower container section 2 is preferably made by welding at the connection point of the side walls 16, 17.

The side walls 16, 17 are at least partially cylindrical, with the side wall 17 being arranged at least partially concentrically to the side wall 16, and with the cylindrical part of the lower container section 3 having a larger inner diameter than the cylindrical part of the upper container section 2. The upper container section 2 extends with its bottom end partially into the lower container section 3.

An upper loading zone 18 of the loading chamber 7 is radially bounded by the cylindrical side wall 16 of the upper container section 2. A further, lower loading zone 19 is radially bounded by the cylindrical side wall 17 of the lower container section 3. The loading zones 18 and 19 merge into one another and form a continuous loading chamber 7. The lower loading zone 19 extends radially beyond the upper loading zone 18 to the side wall 17 of the lower container section 3.

The annular channel 12 is arranged concentrically to the side wall 16 of the upper container section 2. The annular channel 12 is open at the bottom, forming a vertically downward-opening glass passage 20 at the level of a horizontal passage plane 21. The passage plane 21 limits the annular channel 12 vertically downwards and extends through the lower outer edge 38 of the vertical side wall 16 of the upper container section 2. The hot carrier gas 9 enters the second charging zone 19 from the annular channel 12 via the gas passage 20, and the heated carrier gas 10 exits the second charging zone 19 into the annular channel 12 via the gas passage 20.

In the vertical upward direction, the annular channel 12 is closed except for the at least one channel opening 11. The annular channel 12 is closed at the top by an inclined side wall 22, which connects the vertical side wall 16 of the upper container section 2 and the vertical side wall 17 of the lower container section 3. In the illustrated embodiment, the side wall 16 of the upper container section 2 is formed at its bottom end as A hanging wall section 23 is formed. The annular channel 12 is then formed or radially bounded by the annular space between the hanging wall section 23 and an upper region of the cylindrical side wall 17 of the lower container section 3. The gas passage plane 21 lies at the level of the lower outer edge 38 of the hanging wall section 23 of the side wall 16 of the upper container section 2.

The gas passage 20 preferably extends at least substantially in a ring shape over the entire circumferential length of the annular channel 12 and has an annular area of the same width with respect to the gas passage plane 21, which is limited in the radial direction by the side walls 16, 17 of the container sections 2, 3.

The container base 6 has a spherical segment-shaped base wall 24, which on the inside carries a multi-layered insulation 25 formed of insulating bricks 26 and fire-resistant bricks 27. The fill containing the heat-storing material 8 rests on the insulation 25.

The inner surface 28 of the container base 6 is conical. The inner surface 28 extends radially to below the gas passage 20 or to the inner surface of the cylindrical side wall 17 of the lower container section 3. Preferably, the inner surface 28 of the container base 6 rises continuously in a radial direction from the central discharge opening 15 in the container base 6 to the side wall 17 of the lower container section 3. This forms a sliding surface for the heat-storing material 8, which extends radially outwards from the center of the container and reaches below the gas passage 20 of the annular channel 12.

After the storage container 1 is filled with the heat-storing material 8, the position of the fill boundary 29a-29d of the fill surface 30 of the heat-storing material 8 and the fill angle change during storage operation. The fill boundary 29a-29d defines the position of an outer fill surface 30 of the heat-storing material 8 in the lower filling zone 19 adjacent to the annular channel 12. This is shown schematically in Fig. 2.

Preferably, no retaining elements for retaining the heat-storing material are present in the area of the gas passage 20 of the annular channel 12 to the feed chamber 7. Material 8 is provided in the feed chamber 7, so that the heat-storing material 8 is moved towards the ring channel 12 as operation increases and can also rise in the ring channel 12.

Starting from an initial fill boundary 29a with a large angle of repose or steep fill surface 30, during storage operation the fill boundary 29b-d of the heat-storing material 8 shifts increasingly radially outwards and upwards, so that a fill boundary 29d with a small angle of repose or flat fill surface 30 can be achieved, in which the fill surface 30 lies at least partially, preferably completely, within the annular channel 12 and the annular channel 12 is bounded vertically by the fill surface 30 over its entire clear width downwards.

To ensure high heat transfer between the carrier gas 9, 10, good gas separation from the heat-storing material 8, particularly when using ceramic, and more specifically spherical, heat-storing materials 8, and to prevent the heat-storing material 8 from being discharged from the storage container 1 during loading and/or unloading, the heat-storing material 8 is conveyed through the bed at a carrier gas velocity significantly below the minimum fluidization velocity. In particular, the carrier gas velocity is less than 80%, preferably less than 50%, and more preferably less than 25%, of the minimum fluidization velocity.

Starting in particular from the bed porosity of a bed of heat-storing material 8 under minimum fluidization conditions, the viscosity and density of the carrier gas 9, 10, the mean grain or sphere diameter of the heat-storing material 8 and its density, as well as the gas pressure of the carrier gas 9, 10, the minimum fluidization velocity of the carrier gas 9, 10 can be determined, for example, using the Ergun equation known to those skilled in the art, at which fluidization of the bed of heat-storing material 8 does not yet occur when the carrier gas 9, 10 flows through it.

In particular, a flow through the heat-storing material 8 in the area of the gas passage 20 of the annular channel 12 is provided, especially preferably at the level of the gas passage plane 21 with a carrier gas velocity below the minimum fluidization velocity. Preferably, in this context, a structural design of the storage container 1 is provided such that the inner (clear) cross-sectional area 31 of the upper container section 16 and the inner (clear) cross-sectional area 32 of the annular channel 12, in particular at the level of the gas passage plane 21, are preferably at least substantially the same size or wherein the inner (clear) cross-sectional area 32 of the annular channel 12 is larger than the inner (clear) cross-sectional area 31 of the upper container section 16. With the same volume flow rate of the carrier gas 9, 10, fluidization of the bed of heat-storing material 8 can be prevented equally reliably both when the heat-storing material 8 is loaded by supplying hot carrier gas 9 into the storage container 1 and when the heat-storing material 8 is discharged by supplying colder carrier gas 10 into the storage container 1, wherein the carrier gas 9, 10 flows through the bed both in the area of the upper container section 2 with the inner cross-sectional area 31 and in the area of the gas passage 20 of the annular channel 12 with the inner cross-sectional area 32 at a sufficiently low gas velocity below the minimum fluidization velocity.

The storage tank 1 is designed as a pressure vessel, in particular for an operating pressure of, for example, more than 8 bar (absolute), and furthermore, in particular, of, for example, 9 bar (absolute) or more.

The specific mass flow rate of the carrier gas can be between 0.5 and 6.0 kg/(s* ^m² ), based on the internal cross-sectional area 31 of the storage container 1 (Fig. 1).

The operating pressure of the storage tank 1 can be between 6 bar (absolute), in particular 8 bar (absolute) and 10 bar (absolute).

The annular channel 12 can have a heat resistance of more than 1000 °C up to 1500 °C, for example preferably 1200 °C. At this temperature level, the hot carrier gas 9 can be fed to the storage container 1 via the channel opening 11. The carrier gas 9, cooled during loading, can exit the container via the opening 13 in the region of the container dome 4 at a temperature level between 500 °C and 1500 °C, for example at approximately 850 °C (single-container operation) or at 1200 °C (when several storage containers are connected). Storage container 1. It is understood that corresponding heat resistance can also be provided for inlets and outlets of the carrier gas 9, 10 to and from storage container 1, which are not shown in Figures 1 and 2.

The heating of the carrier gas to the charging temperature of the storage container 1 can preferably be carried out by means of electric gas heaters of the high-temperature heat storage unit (not shown).

The opening 11 for the supply of hot carrier gas 9 to the annular channel 12 is preferably arranged opposite the hanging wall section 23 of the side wall 16 of the upper container section 2. The gas supply is thus directed towards the hanging wall section 23. At the hanging wall section 23, the carrier gas flow is deflected towards the gas passage 20.

The inner cross-sectional area 31, which is bounded by the side wall 16 of the upper container section 2, can be in a range between 3 m ² and 100 m ² , in particular between 30 m ² and 80 m ² .

To ensure a uniform flow through the pile in the feed chamber 7, the height-to-diameter ratio can be between 0.5 and 1.8, preferably between 1.0 and 1.6. The height-to-diameter ratio (Fig. 2) is based on the active pile height 33 in the upper container section 2 and the inner diameter 34 of the container section 2, which is defined by the cylindrical side wall 16 of the upper container section.

As shown in detail in Fig. 2, the bottom wall 24, which is made of a steel material, has thermal insulation 25 on its inner side. The insulation 25 is formed by an outer layer 27 facing the filling chamber 7, for example made of refractory bricks, and an adjacent inner layer 26, for example made of insulating bricks. This achieves high compressive strength in the area of the tank bottom 6, since the storage tank 1 is subject to high static and dynamic pressure loads in this area due to the load of heat-storing material 8 on the tank bottom 6.

The lower wall section 23 of the upper container section 2, designed as a hanging wall, is also subject to a [condition] due to the laterally adjacent fill. high mechanical stress. Furthermore, the wall section 23 borders the ring channel 12 and is subjected to high thermal stress, particularly during the loading of the storage tank 1. For sufficient thermal insulation and high compressive strength, the suspended wall section 23 has, on its side facing the loading chamber 7 and on the side facing the ring channel 12, a refractory outer layer 36 made of a high-hardness insulating material and an inner layer 37 with lower hardness, radially adjacent to the outer layer 36. The outer layer 36 can be formed by refractory bricks, while the inner layer 37 can be formed by insulating concrete.

Furthermore, the lower wall section 23, designed as a suspended wall, has a metallic support element 45, which may in particular be a cylindrical steel component. The support element 45 is preferably welded to the side wall 16 of the upper container section 2 in the area of the connection point between the upper container section 2 and the lower container section 3.

Furthermore, a cooling device 39, shown only schematically in Fig. 2, is provided to cool the support element 45 located in the wall section 23, which is designed as a suspended wall. The cooling device 39 has an inlet 40 and an outlet 41 for cooling water, which is guided through a cooling coil running around the wall section 23. The cooling coil is embedded in the inner layer 37 of the insulation.

The sloping wall 22 and the side wall 17 of the lower container section 3, which define the annular channel 12 upwards and radially outwards, also have multi-layered insulation applied to the inside of the container walls 17, 22. Again, an outer layer 36 with higher hardness, for example formed by refractory bricks, facing the annular channel 12, and an inner layer 37 with lower hardness, for example formed by insulating concrete, facing the outer container walls 17, 22, can be provided.

In addition, the ring channel 12 has rounded inner edges in the connection area of the inclined wall 22 of the lower container section 3 to the side wall 16 of the upper container section 2 to increase pressure stability.

On the side of a conduit section 35 of the ring channel 12, which opens into the channel opening 11, the ring channel 12 is also equipped with a previously described equipped with two-layer insulation, which is formed by an outer layer 36 with higher hardness directed towards the annular channel 12 and an inner layer 37 with lower hardness.

The dome 4 of the upper tank section 2 has an outer layer 42 facing the charging chamber 7, made of a material with higher hardness, and an inner layer 43 adjacent to it in a radial direction to the outside, made of an insulating material with lower hardness, as well as an outer tank wall 44, wherein the outer layer 42 can be a sprayed insulating layer made of refractory bricks and the inner layer 43 can be a layer of sprayed insulating concrete.

Fig. 3 schematically shows an alternative embodiment of the storage container 1 shown in Fig. 2. Identical reference numerals denote functionally and/or structurally identical features of the storage container 1.

In contrast to the storage container 1 shown in Fig. 2, the storage container 1 shown in Fig. 3 is provided in such a way that the upper container section 2 rests on the lower container section 3 at its base or is supported on the lower container section 3 by a support structure 46 which is not shown in detail.

The supporting structure 46 can be a masonry structure made of temperature-resistant bricks. In particular, the supporting structure 46 does not have any metallic support elements. The weight of the upper container section 2 is transferred to the lower container section 3 via the supporting structure 46. Cooling of the supporting structure 46 is not required if it does not have any metallic support elements.

Figure 2 shows, by way of example only, an embodiment in which the supporting structure 46 has a radially inner and a radially outer insulating layer 36 made of a temperature-resistant material, in particular temperature-resistant bricks. In the area between the outer layer 36, a cement-based inner layer 37 can be provided, which consists of an insulating material with lower hardness.

It is not shown that the upper container section 2 may also have a different structure of the supporting structure 46 at its lower bottom end, where the supporting structure 46 may, for example, be made entirely of refractory brickwork. Furthermore, Fig. 2 schematically shows that the supporting structure 46 can have ring-shaped column-like structural sections 47 which converge in an arc shape towards the top, so that in particular a vault-like supporting structure 46 is formed in certain areas.

Openings 48 are provided between adjacent structural sections 47 to allow the heat storage material 8 to pass from the feed chamber 7 or the feed zone 19 into the annular channel 12. For this purpose, the opening width of the openings 48 is a multiple of the particle size of the heat storage material 8, thus ensuring free passage of the heat storage material 8 through the openings 48.

It is understood that the support structure 46 may also have a geometric design and/or a different structure than that shown in Fig. 3. For example, longitudinal or transverse slots may be provided that penetrate a substantially ring-shaped, planar support structure 46 to allow the heat storage material 8 to pass through.

Reference symbol list:

1 storage container 25 insulation

2 Container section 26 Inner layer

3 Container section 27 Outer layer

4 Container dome 30 28 Inner surface

5 side wall 29 fill limit

6 Container bottom 30 Pouring area

7 Loading area 31 Cross-sectional area

8 Heat storage material 32 Cross-sectional area

9 Carrier gas 35 33 Filling height

10 Carrier gas 34 Inner diameter

11 Channel opening 35 Pipe section

12 Ring channel 36 Outer layer

13 Container opening 37 Inner layer

14 Filling opening 40 38 Outer edge

15 Discharge opening 39 Cooling unit

16 Side wall 40 Supply line

17 Side wall 41 Derivation

18 Feed zone 42 Outer layer

19 Feed zone 45 43 Inner layer

20 Gas passage 44 Container wall

21 Gas passage level 45 Support element

22 Side wall 46 Supporting structure

23 Wall section 47 Structural section

24 Floor wall 50 48 Opening

Claims

Patent claims: 1. High-temperature thermal energy storage system with a storage vessel (1) for storing thermal energy, in particular for providing high-temperature heat for power generation and/or as process heat for industrial plants and processes, further in particular with a storage capacity of greater than 50 MWh, preferably greater than 100 MWh, and a heat resistance of the storage vessel (1) of 1000 °C to 1500 °C, wherein the storage vessel (1) has an upper vessel section (2) and a lower vessel section (3) connected to the upper vessel section (2), and the upper vessel section (2) forms an upper vessel closure, in particular a vessel dome (4), and the lower vessel section (3) forms a vessel bottom (6), wherein the upper vessel section (2) and the lower vessel section (3) define a charging chamber (7) for charging the storage vessel (1) with a heat-storing material (8), wherein during a charging cycle a charge introduced into the storage vessel (1) a heat-storing material (8) is permeable in a vertical direction by a hot carrier gas (9), in particular hot air, to charge the heat-storing material (8) by heat transfer from the hot carrier gas (9) to the heat-storing material (8), wherein during a discharge cycle the supply of a colder carrier gas (10), in particular cold air, is permeable in a vertical direction to discharge the heat-storing material (8) by heat transfer from the heat-storing material (8) to the colder carrier gas (10) and to heat the carrier gas (10), and wherein the heat-storing material (8) does not undergo a phase change during the charging cycle and during the discharge cycle, characterized in that the carrier gas (9, 10) can be supplied to the supply chamber (7) via an annular channel (12) and/or discharged from the supply chamber (7) via the annular channel (12). 2. Heat storage device according to claim 1, characterized in that the lower container section (3) is arranged concentrically to the upper container section (2), wherein the lower container section (3) has a larger internal cross-sectional area than the upper container section (2) and the upper container section (2) partially extends into the lower container section (3) on its bottom side. 3. Heat storage device according to claim 1 or 2, characterized in that the charging chamber (7) is formed by an upper charging zone (18) and a lower loading zone (19), wherein the upper loading zone (18) is bounded transversely to the longitudinal direction of the storage container (1), in particular radially outwards, by the upper container section (2) and the lower loading zone (19) is bounded transversely to the longitudinal direction of the storage container (1), in particular radially outwards, by the lower container section (3), wherein, preferably, the lower loading zone (19) extends transversely to the installation direction of the storage container (1) extends outwards, particularly in a radial direction, over the upper feed zone (18). 4. Heat storage device according to one of the preceding claims, characterized in that the annular channel (12) is arranged concentrically to the filling chamber (7), in particular concentrically to the upper container section (2), wherein, preferably, the annular channel (12) extends over the entire circumferential length of a side wall (16) of the upper container section (2). 5. Heat storage device according to one of the preceding claims, characterized in that the upper container section (2) is designed as a hanging wall section (23) at the bottom end, in particular wherein the hanging wall section (23) has wall cooling, and/or that the upper container section (2) is supported by a supporting structure (46) on the lower container section (3). 6. Heat storage device according to one of the preceding claims, characterized in that the annular channel (12) is open to the charging chamber (7), in particular to the lower charging zone (19), wherein the opening forms a gas passage (20) for carrier gas (9, 10) to the charging chamber (7), in particular wherein the annular channel (12) is closed laterally to the upper charging zone (18). 7. Heat storage device according to one of the preceding claims, characterized in that the annular channel (12) in the area of the gas passage (20) to the feed chamber (7) is free of retaining elements designed to retain the heat-storing material (6) in the feed chamber (7). 8. Heat storage device according to one of the preceding claims, characterized in that the inner cross-sectional area (32) of the annular channel in the area of the gas passage plane (21) of the gas passage (2) is greater than or equal to the inner cross-sectional area (31) of the upper container section (2). 9. Method for operating a high-temperature thermal energy storage system of the aforementioned type with a storage container (1) for storing thermal energy, wherein the storage container (1) has a charge of a heat-storing material (8), wherein during a charging cycle the charge is flowed through in a vertical direction by a hot carrier gas (9), in particular hot air, to charge the heat-storing material (8) by heat transfer from the hot carrier gas (9) to the heat-storing material (8), wherein during a discharging cycle the charge is flowed through in a vertical direction by a colder carrier gas (10), in particular cold air, to discharge the heat-storing material (8) by heat transfer from the heat-storing material (8) to the colder carrier gas (10) and to heat the carrier gas (10), and wherein the heat-storing material (8) does not undergo a phase change during the charging cycle and during the discharging cycle. through, characterized in that a supply and/or discharge of carrier gas (9) into the storage container (1 ) and/or from the storage container (1 ) during the charging cycle and/or during the discharging cycle takes place via a ring channel (12). 10. Method according to claim 9, characterized in that a flow through the heat-storing material (8) in the region of the gas passage (20) annular channel (12) is provided with a carrier gas velocity below the minimum fluidization velocity, in particular wherein the carrier gas velocity is less than 80%, preferably less than 50%, further preferably less than 25%, of the minimum fluidization velocity and/or wherein the mass flow rate of the carrier gas (9) with respect to the inner cross-sectional area (31) of the upper container section (2) is between 0.2 kg/(s*m ² ) and 10.0 kg/(s*m ² ), in particular between 0.5 kg/(s*m ² ) and 6.0 kg/(s*m ² ).