High-temperature storage and energy conversion system

Abstract

System for high-temperature storage and energy conversion with latent heat storage material 1, characterized in that the discharge of a high-temperature storage 13 takes place via a heater 16 of a hot gas engine 18, which is located in a heater chamber housing 15, which is located directly inside the latent heat storage material 1 and the latent heat storage material 1 consists of a salt, such as sodium chloride, or aluminum.

Description

[0001] High-temperature storage systems are known as sensible heat storage systems or latent heat storage systems. While sensible heat storage systems make their heat content usable by cooling the storage material, latent heat storage systems utilize the isothermal phase change, for example, from the liquid to the solid state of the storage material, and thereby provide the heat of solidification. It is well known in the energy sector that latent heat storage systems have significantly higher usable heat contents per kilogram of storage material than sensible heat storage systems. A general challenge of heat storage systems is converting their stored energy into electrical energy. According to the laws of thermodynamics, higher mechanical efficiencies can be achieved at higher storage temperatures with power machines that are suitable for converting thermal energy into mechanical energy and that can, in principle, be connected to storage systems.Storage tanks with higher temperatures require appropriate heat resistance and more extensive insulation. Suitable heat transfer components with high thermal conductivity must be connected to or integrated into the storage tank for both charging and discharging heat flows.

[0002] For example, if a high-temperature storage system is electrically charged, electric heating elements with high heat resistance are available for this purpose. Discharge can be achieved, for example, with an airflow that is heated within the storage system and then drives a gas turbine or a hot gas engine. These power units then convert the high-temperature heat into mechanical energy and low-temperature heat.

[0003] The following sources were considered significant regarding the state of the art: 1. DE 10 2013 110 117 A1: The patent application discloses a method for storing thermal energy in at least one thermal storage block and at least one extraction device for extracting stored thermal energy. However, the patent does not use a latent heat storage material, but exclusively ceramics, and the energy extraction takes place via embedded pipes in which water is evaporated and the steam then drives turbines. 2. DE 10 2019 127 431 A1: The patent application discloses a method for storing electrical energy in the form of thermal energy in a high-temperature storage system. The storage medium is a liquid salt mixture, but this only has an operating temperature of 230 °C to 570 °C and is therefore only conditionally suitable for generating mechanical energy with high efficiency. Furthermore, the conversion to mechanical energy also takes place via turbines. 3. DE 20 2016 003 851 U1: The utility model specification discloses a method for storing electrical energy in the form of heat in ceramic tubes. The conversion is carried out via steam engines. It does not disclose a combination of a special hot gas engine with an angled heater operating on the Ericsson principle and high-temperature storage. 4. A publication from the Technical University of Central Hesse (ISBN: 978-3-00-072104-5) describes a high-temperature storage system up to 1200 °C with subsequent utilization via a hot gas turbine. Refractory concrete is used as the storage material, and the flow distribution is ensured by the geometric arrangement of the storage components instead of by using fill material with variable grain size. 5. WO 2016 / 165 724 A1: The patent application discloses a method for high-temperature storage via a packed bed. Heat is then converted into electrical energy via a gas turbine. 6. DE 10 2012 108 733 A1: The patent application discloses a system for high-temperature storage and energy conversion consisting of a high-temperature storage unit (2.2) and a discharge engine (1), wherein the discharge engine is a hot gas engine. Paragraph

[0056] of document D1 mentions turbine gas, which heats a heat transfer fluid WT. Paragraph

[0059] also refers to the heat transfer fluid WT in connection with a gas turbine process. 7. DE 44 02 406 A1: The patent application shows a thermohydraulic working machine which contains sheet metal inserts for distributing the working gas in the heat exchanger. 8. DE 000002340269 B2: The patent shows a heat engine combined with a storage unit. The heat engine is not a two-cycle Stirling engine. The heater is not located directly in a storage tank. 9. DE 10 2014 011 241 B3: The patent shows an innovative 2-cycle Stirling engine with a heater whose main axis is perpendicular to the motor axis; this system is described without a memory.

[0004] The present invention describes according to Fig. 1-3 A system for high-temperature storage and energy conversion, consisting of a high-temperature storage unit 13 and a hot gas engine 18, characterized in that the discharge engine is designed as a hot gas engine according to patent DE 10 2014 011 241 B3. This hot gas engine 18 has the special feature that the heater extending from the expansion cylinder is positioned perpendicular to the axis of movement of the pistons. The combination of the hot gas engine 18 and the high-temperature storage unit 13 is very advantageous because the special hot gas engine 18, which operates according to the Ericsson principle, has a higher mechanical efficiency than conventional Stirling engines and comparable gas turbine processes, and therefore ensures better utilization of the high-temperature storage capacity. The special design of this hot gas engine creates optimal conditions for integration into a high-temperature storage unit.The elevated arrangement of the expansion cylinder above the hot gas engine block allows for a heater 16 in the expansion area of ​​the hot gas engine 18 without additional dead space or additional pipe bends, and whose main axis is perpendicular to the cylinder axis. This is a unique feature of the hot gas engine 18 according to DE 10 2014 011 241 B3 compared to other Stirling engines: For the integration of the hot gas engine 18 into the high-temperature storage tank 13, the heat supply to the heater 16 of the hot gas engine 18 can be achieved without an additional heat transfer medium in gaseous or liquid form via a horizontally oriented heater chamber housing 15 when the hot gas engine is stationary. The heater chamber housing 15 encloses the heater 16. This proves to be very advantageous with regard to the integration of the hot gas engine heater 16 into a high-temperature storage tank 13.Since in other Stirling engines the heater axis is parallel or aligned with the cylinder axis, the hot gas engine 18 would either have to be laid horizontally or inserted vertically, with its heater 16 facing forward, into the high-temperature storage tank 13 from above or below. If the heater 16 of the hot gas engine 18 is inserted from above into the high-temperature storage tank 13, the entire hot gas engine 18 will overheat, and if the heater 16 is inserted from below into the high-temperature storage tank 13, the hot gas engine 18 must be positioned below the heavy high-temperature storage tank 13. This is difficult to construct, as the massive high-temperature storage tank 13 should ideally be placed on the ground.

[0005] If the heater 16 of the hot gas engine 18 were inserted into the high-temperature storage tank 13 from above or below, the overall system would exceed the total height of typical rooms, which is a major disadvantage.

[0006] If other machines were redesigned so that the heater of the hot gas engine 16 was also arranged at a right angle to the cylinder axis, additional dead space losses and pressure losses due to pipe bends would have to be accepted. Designers and engineers working in the field of hot gas engines are aware that such losses must be avoided at all costs, as they reduce the efficiency and power output of the machines.

[0007] The system according to the invention uses aluminum or sodium chloride as the latent heat storage material 1. Sodium chloride is inexpensive to acquire and has a high heat storage capacity. Furthermore, sodium chloride is not harmful to health, and reuse or disposal poses no problems. Its melting point of 801°C creates ideal conditions for high-temperature storage. Aluminum has a similar mass-specific heat storage capacity to sodium chloride and a melting point of 660°C. However, it is significantly more expensive and more difficult to process. Nevertheless, it is also harmless, and its composition remains unchanged when used as the latent heat storage material 1. This means it can be recycled later.

[0008] The execution of the system according Fig. 1-3, can be carried out in the form of the discharge of the high-temperature storage 13 via the heater 16 of the hot gas engine 18, which is located in a heater chamber housing 15 that is located directly inside the latent storage material 1.

[0009] A system according to the invention also consists in a heater chamber housing 15 enclosing the heater 16 having a tubular or cuboid surface.

[0010] The surface of the heater chamber housing 15 can have a comb-shaped profile extending over its depth, the projections of which are located precisely in the gaps of the outer heater tubes, so that contact or the closest possible proximity occurs between the heater tube and the heater chamber housing 15, and the hot gas engine 18 together with the heater 16 can still be mounted and dismounted.

[0011] An improvement in heat transfer according to the invention in the heater chamber housing 15 is efficiently achieved by filling with, for example, heat-resistant steel wool or filler materials such as Raschig rings made of steel or ceramic.

[0012] In the design of an external heater 16 of the hot gas engine 18 according to Fig. 8 provides a gas line 14 for connecting the engine to the storage unit for heat extraction (discharging) from the high-temperature storage unit 13.

[0013] A high-temperature fan for hot gas conveying 17 conveys the gas through the storage material bed 3. In doing so, it absorbs the high-temperature heat and flows via insulated pipes into the heater chamber housing 15 of the hot gas engine 18.

[0014] Another system according to the invention according to the Fig. 4-8, is characterized in that the high-temperature storage unit 13 is combined from an internal latent heat storage unit and a sensible heat storage unit surrounding the latent heat storage unit.

[0015] According to the invention, two methods are proposed for distributing the gas flow evenly. In the design according to the Fig. 4, Fig. 5 and Fig. 8. An annular perforated plate 5, in combination with a storage material bed 3, ensures the uniform gas distribution around the latent heat storage material 1. This perforated plate 5 has an increasing hole size towards the area facing away from the gas inlet (rear of the storage unit). The storage material bed 3 acts as a sensible heat storage element. Another embodiment of the system is described in Fig. 6 and Fig. Figure 7 illustrates this. According to the invention, the storage material bed 3 not only performs the function of the sensitive storage material but can also ensure a uniform distribution of the charging and discharging gas flow. This has the advantage that the gas flows uniformly through the latent heat storage material 1 at every level of the high-temperature storage unit 13, thereby always achieving a uniform temperature distribution within the high-temperature storage unit 13. A storage material bed 3, which ensures a uniform distribution of the gas flow and is distributed around the latent heat storage material 1 with variable permeability, is shown in Figure 7. Fig. 6. This storage material 3 has a fine grain size in the area of ​​the gas inlet, which becomes coarser towards the side facing away from the gas inlet (rear of the storage unit), thus having an increasing permeability.

[0016] The system can be used after Fig. 1 and Fig. The high-temperature storage unit 13 has three filling and flushing ports 19 through which the latent heat storage material 1 enters the high-temperature storage unit 13. Evacuation and flushing ports 20 ensure the removal of any remaining air inside the high-temperature storage unit 13 before it is sealed. If salt is used as the latent heat storage material 1, it can be flushed out of the high-temperature storage unit 13 and then reused when the unit is to be removed.

[0017] The system can operate the hot gas engine 18 as a heat pump for deep discharge of the high-temperature storage tank. For this purpose, its heater 16 is used as a heat exchanger for the storage tank, which serves as the heat source, and the engine cooler, which normally releases its waste heat as usable heat, is operated as a heat exchanger for the heat sink. Usable heat is even available when the hot gas engine 18 is not running as a power engine, but is driven as a working machine by its variable-speed generator. In this case, the clockwise cycle becomes a counterclockwise cycle.

[0018] Another embodiment of the system is characterized in that a control unit allows the system to operate according to tariffs, enabling the use of electricity at low tariffs for charging and electricity at high tariffs for discharging. The control unit can also determine whether a deep discharge of the storage system is occurring. List of reference symbols for Figures 1-8 1. Latent storage material 2. Temperature-resistant container for storage material (e.g., steel pipe) 3. Storage material fill, gas-permeable 4. High-temperature insulation 5. Ring-shaped perforated plate for even distribution of the gas. 6. Storage tank connection pipe 7. Ring chamber for gas distribution in front of the perforated plate 8. Mounting tube for electric heating element 9. Electric heating elements for heating the storage medium 10. Connection cable for heating element 11. Inspection cover of the high-temperature storage tank, insulated 12. Jacket of the high-temperature storage unit 13. High-temperature storage ( Fig. 1-8) 14. Gas line for connecting the engine to the storage tank 15. Heater chamber housing 16. Hot gas engine heater 17. High-temperature fan for hot gas conveying 18. Hot gas engine, e.g., according to patent DE 10 2014 011 241 19. Filling and rinsing nozzle 20. Evacuation and flushing nozzles

Claims

[1] High-temperature energy storage and conversion system with latent heat storage material 1, characterized by , that the discharge of a high-temperature storage 13 takes place via a heater 16 of a hot gas engine 18, which is located in a heater chamber housing 15, which is located directly inside the latent storage material 1, and the latent storage material 1 consists of a salt, such as sodium chloride, or aluminum. [2] System according to claim 1, characterized by , that the heater chamber housing 15 enclosing the heater 16 has a tubular or cuboidal surface. [3] System according to claim 2, characterized by , that the surface of the heater chamber housing 15 has a comb-shaped profile extending over its depth, the projections of which are located precisely in the gaps of the outer heater tubes, such that contact or the closest possible approach occurs between the heater tube and the heater chamber housing 15. [4] System according to claims 1 to 3, characterized by , that the heat transfer in the heater chamber housing 15 is made more efficient by filling with heat-resistant steel wool or filler materials such as Raschig rings made of steel or ceramic. [5] System for high-temperature storage and energy conversion with latent heat storage material 1 according to claim 1, characterized by , that the discharge of the high-temperature storage 13 takes place via the heater 16 of the hot gas engine 18, which is located in the heater chamber housing 15, but this is not located inside the latent heat storage material 1, but outside the high-temperature storage 13, which contains a material bed 3 as sensible storage material in the outer area, from there a connection exists via a gas line 14 to the hot gas engine 18, and the gas for heat transfer is conveyed from the latent heat storage material 1 to the hot gas engine 18 with a high-temperature fan 17.

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