Sand energy storage efficient high-quality thermoelectric conversion system and method

Abstract

This application provides a high-efficiency and high-quality thermoelectric conversion system and method for sand energy storage. The system includes a concentrating solar collector with heating components and a cold sand return component; an energy storage device connected to the heating components for storing or releasing solar-heated sand particles at different sunlight periods; a fluidized bed heat exchanger with a fluidized bed through which gas is introduced; the fluidized bed is connected to the heating components and / or the energy storage device for using gas to fluidize the received sand particles and for gas-solid heat exchange with the fluidized sand particles to heat the gas; and a combined power generation device connected to the fluidized bed for generating electricity using the thermal energy of the gas. The system provided by this invention solves the problems of low thermal storage efficiency, long-term system instability, and inability to quickly release and recover thermal energy in current sand energy storage systems.

Description

Technical Field

[0001] This application relates to the field of thermoelectric conversion technology, and in particular to a high-efficiency and high-quality thermoelectric conversion system and method for sand storage energy. Background Technology

[0002] In 2023, global carbon dioxide emissions from fossil fuels reached a record high of 36.8 billion tons, far exceeding nature's capacity to absorb carbon dioxide. The carbon dioxide and pollutants produced by burning fossil fuels will not only contribute to global climate problems but also cause severe air, ocean, and soil pollution. Faced with this challenge, actively exploring and adopting sustainable and clean energy alternatives has become particularly urgent.

[0003] Solar energy, as the most abundant and widespread clean energy source on Earth, is considered a representative of what can meet humanity's future energy needs. Solar power generation does not produce greenhouse gases or other pollutants, and its operating costs have decreased significantly with technological advancements, making it a promising application. However, solar energy utilization is affected by weather and diurnal variations, making it impossible to guarantee a continuous and stable energy output, which contradicts the long-term stable energy demands of power grids and industry. Energy storage technology can store energy when there is a surplus and release it during peak demand periods, thus achieving a balance between energy supply and demand. Therefore, configuring energy storage devices in renewable energy power generation systems to convert intermittent energy into long-term stable energy is essential. Currently, various energy storage technologies exist on the market, such as battery storage, pump storage, and phase change material storage, but these technologies generally suffer from high costs, short lifespans, and significant environmental impacts.

[0004] Sand energy storage technology, as an emerging energy storage method, has attracted widespread attention due to its unique advantages. Sand is an abundant and inexpensive natural resource, widely distributed globally. Therefore, the construction and operation costs of sand thermal energy storage systems are relatively low. Moreover, sand energy storage technology also has advantages such as high heat capacity, chemical stability, environmental friendliness, and high-temperature thermal storage capabilities.

[0005] Despite the advantages mentioned above, sand thermal storage technology still faces technical challenges in practical applications, such as low thermal storage efficiency, unstable long-term system operation, and the inability to quickly release and recover heat energy. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a high-efficiency and high-quality thermoelectric conversion system for sand energy storage, solving the technical problems of low thermal storage efficiency, long-term system instability, and inability to rapidly release and recover heat energy in current sand energy storage applications. A second objective of this invention is to provide a high-heat-release thermoelectric conversion method for sand energy storage.

[0007] To achieve one of the objectives, the first aspect of this invention provides a high-efficiency and high-quality thermoelectric conversion system for sand energy storage, the technical solution of which is: A high-efficiency and high-quality thermoelectric conversion system for sand energy storage, the system comprising: A solar concentrator includes a heating component and a cold sand recirculation component that are interconnected. The heating component contains sand grains and is used to concentrate solar energy onto the sand grains. The cold sand recirculation component is used to provide the heating component with aerodynamic force to drive the sand grains to flow. An energy storage device, connected to the heating component, is used to store or release the solar-heated sand particles at different times of sunlight. A fluidized heat exchanger includes a fluidized bed in which gas is introduced; wherein the fluidized bed is connected to the heating component and / or the energy storage device, and is used to fluidize the received sand particles using the gas and to perform gas-solid heat exchange with the sand particles to heat the gas; A combined power generation unit, connected to the fluidized bed, is used to generate electricity using the thermal energy of the gas.

[0008] Optionally, the cold sand recirculation assembly includes: The cooling sand tank is connected to both the heating assembly and the fluidized bed. The first blower, connected to the cold sand tank, is used to forcefully return the sand particles after gas-solid heat exchange from the fluidized bed to the heating assembly.

[0009] Optionally, multiple heating components are provided, and the multiple heating components are sequentially connected; wherein each heating component includes: The heat collection tube allows the sand particles to flow through its interior; A grooved concentrator mirror has a recessed surface forming a groove, and the heat collection tube is disposed within the groove.

[0010] Optionally, the heat collection tube extends along a length direction parallel to the slot opening, and the extension length of the heat collection tube is the same as the length of the slot opening.

[0011] Optionally, the energy storage device includes at least one thermal storage tank, each of which is connected to the heating component and the fluidized bed respectively; wherein, the outer periphery of each thermal storage tank is covered with a heat-insulating and refractory insulation material, which is used to maintain the temperature of the sand particles inside the thermal storage tank.

[0012] Optionally, the fluidized heat exchanger further includes: A cyclone separator, connected to the fluidized bed, is used to remove impurities from the heated gas; The second blower is connected to the fluidized bed and is used to input the gas into the fluidized bed.

[0013] Optionally, the combined power generation unit includes sequentially connected: A turbine generator, connected to the fluidized bed, is used to generate electricity using the heated gas. A steam turbine generator set is connected to the turbine generator via a heat exchanger set, and is used to heat water to form steam by utilizing the waste heat of the gas discharged from the turbine generator, and to generate electricity through the steam. The heating terminal is connected to the steam turbine generator set via a heat exchanger and is used to provide heating by utilizing the waste heat of the steam discharged from the steam turbine generator set.

[0014] Optionally, the heat exchanger is connected to the heat exchanger group via a water pump to circulate water after waste heat utilization into the heat exchanger group; and the heat exchanger group is connected to the fluidized bed via the second blower to circulate gas after work is performed into the fluidized bed.

[0015] Optionally, the cold sand tank is located below the fluidized bed and is connected to the fluidized bed via a reflux pipe.

[0016] To achieve the second objective, the second aspect of this invention provides a high-heat-release thermoelectric conversion method for sand energy storage, the technical solution of which is: A high-heat-release thermoelectric conversion method for sand energy storage, relying on the high-efficiency and high-quality thermoelectric conversion system for sand energy storage provided in the first aspect of the present invention, includes the following steps: During the first period of sunlight, solar energy is concentrated onto the sand grains using a heating component to heat the sand grains. The heated sand particles are introduced into an energy storage device and a fluidized heat exchanger, respectively, and the energy storage device is used to store the sand particles. During the second period of illumination, the high-temperature sand particles stored in the energy storage device are released into the fluidized heat exchanger. The sand particles are fluidized by the gas in the fluidized heat exchanger, and gas-solid heat exchange is performed between the fluidized sand particles to heat the gas. The heated gas is introduced into a combined power generation unit, and the thermal energy of the gas is used to generate electricity.

[0017] Compared with the prior art, this application has the following significant advancements: This invention provides a high-efficiency and high-quality thermoelectric conversion system for sand energy storage. The system includes a concentrating solar collector with interconnected heating and cold sand return components. The heating component contains sand particles and is used to concentrate solar energy onto the sand particles. The cold sand return component provides aerodynamic force to the heating component to drive the sand particles. An energy storage device connected to the heating component stores or releases the solar-heated sand particles at different sunlight periods. A fluidized bed heat exchanger is provided, in which gas is introduced. The fluidized bed is connected to the heating component and / or the energy storage device, and is used to fluidize the received sand particles using the gas and to perform gas-solid heat exchange with the fluidized sand particles to heat the gas. A combined power generation device connected to the fluidized bed is used to generate electricity using the thermal energy of the gas.

[0018] The system provided in this invention, through the multi-stage linkage of a concentrating solar collector, an energy storage device, a fluidized bed heat exchanger, and a combined power generation device, can utilize the high specific heat capacity and high-temperature heat storage capacity of sand particles under dense-phase pneumatic transport conditions to achieve long-term stable storage of solar energy, which can then be used for power generation or heating. The stored heat energy in the sand particles can be controllably released for power generation or heating during periods of user demand. The solar energy utilization efficiency can reach 35%, and the load of heat release power generation can be adjusted, achieving effective utilization of solar energy. The system's manufacturing process is simple and easy to scale up, with low equipment investment costs and great potential for large-scale utilization. In summary, this system solves the problems of inefficiency, instability, and poor thermal energy utilization response of traditional sand thermal storage technology. Attached Figure Description

[0019] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a process flow diagram of the high-efficiency and high-quality thermoelectric conversion system for sand energy storage according to an embodiment of this application; Figure 2 This is a three-dimensional structural schematic diagram of the heating assembly described in one embodiment of this application; Figure 3 This is a front view of the heating assembly according to an embodiment of this application; Figure 4 This is a front sectional view of a multi-stage countercurrent fluidized bed according to an embodiment of this application; Figure 5 This is a flowchart of the steps of the high heat release thermoelectric conversion method for sand energy storage according to an embodiment of this application.

[0021] Explanation of reference numerals in the attached figures: 1. Concentrating solar collector; 11. Parabolic trough concentrator; 12. Solar collector tube; 13. Pipe support; 14. Support; 2. Thermal storage tank; 3. Fluidized bed; 31. Air inlet; 32. Air outlet; 33. Sand inlet; 34. Sand outlet; 4. Cold sand tank; 5. Turbine; 6. Generator; 7. Steam turbine; 8. Heat exchanger; 9. Water pump; 10. Condenser; 15. First blower; 16. Second blower. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Please see Figure 1 , Figure 1 A process flow diagram of the high-efficiency and high-quality thermoelectric conversion system for sand energy storage of the present invention is shown; Figure 1 Different shaped line segments represent different material flows. A first aspect of this invention provides a high-efficiency, high-quality thermoelectric conversion system for sand energy storage. The system includes: a concentrating solar collector 1, comprising a heating component and a cold sand return component connected to each other; the heating component contains sand particles and is used to concentrate solar energy onto the sand particles; the cold sand return component provides aerodynamic force to the heating component to drive the sand particles to flow; an energy storage device, connected to the heating component, for storing or releasing the solar-heated sand particles at different light periods; a fluidized heat exchange device, including a fluidized bed 3, into which gas is introduced; wherein the fluidized bed 3 is connected to the heating component and / or the energy storage device, for using the gas to fluidize the received sand particles and to perform gas-solid heat exchange with the fluidized sand particles, heating the gas; and a combined power generation device, connected to the fluidized bed 3, for generating electricity using the thermal energy of the gas.

[0024] Specifically, sand is used as the thermal storage medium, which is low-cost and recyclable. The system operates on solar energy, has no carbon emissions, and has low maintenance costs, resulting in good environmental and economic benefits. Following the flow path of the sand, the concentrating solar collector 1, the energy storage device, the fluidized heat exchanger, and the combined power generation device are arranged sequentially.

[0025] In this embodiment, the concentrating solar collector 1 serves as the front-end component, providing sand particles as the heat carrier and dividing them into several streams that are then transported to the energy storage device and / or fluidized heat exchanger located at its rear end. In this embodiment, the cold sand recirculation component provides the sand particles and pneumatically transports them to the rear-end heating component, from where they continue to flow to the energy storage device connected to the heating component. Within the heating component, the solar heat is concentrated and directly applied to the sand particles, causing them to rapidly absorb heat and heat up, thus improving the photothermal conversion efficiency.

[0026] In some embodiments, the cold sand reflux device in the concentrating solar collector 1 also serves as the tail end of the system and is connected to the fluidized bed 3 at the rear end. Therefore, the sand particles provided are sand particles that have undergone gas-solid heat exchange in the fluidized bed 3, so as to realize a closed-loop cycle of sand heat collection and energy storage.

[0027] The heating components may include a concentrator and a heating container. The concentrator, such as a Fresnel mirror, a plane mirror array, a parabolic trough concentrator, or a dish concentrator, is used to concentrate sunlight. The heating container holds sand grains and allows them to flow smoothly under pneumatic conveying conditions. The concentrator and heating container are arranged according to the light reflection path so that solar energy is reflected and focused onto the heating container and the flowing sand grains within it. This utilizes the high specific heat capacity and high-temperature heat storage capacity of sand under dense-phase pneumatic conveying conditions, allowing the sand temperature to rise to over 900°C, providing a high-quality heat source for subsequent heat exchange and energy storage.

[0028] The energy storage device serves as a heat transfer station to store the high-temperature sand grains after they have absorbed heat, and releases the heat when needed. Specifically, the solar-heated sand grains are selectively stored or released during different periods of sunlight to adapt to the timing of power generation or heating.

[0029] For example, high-temperature sand particles can be stored in a well-insulated energy storage tank. The top of the tank is connected to a heating component, and the bottom of the tank is connected to a fluidized bed 3. After absorbing heat during the first illumination period, the sand particles are stored in the heat storage tank 2, and the stored high-temperature sand particles are gradually released during the second illumination period.

[0030] In summer, the first lighting period can be set to the daytime working period, and the second lighting period can be set to the nighttime working period. In winter, depending on the operating environment, the first lighting period can be set to the period with sufficient sunlight, and the second lighting period can be the period with insufficient sunlight.

[0031] For example, the first period of illumination is daytime or from 7 a.m. to 4 p.m. The second period of illumination is the remaining time of the day excluding the first period of illumination or the peak electricity consumption period for users.

[0032] Therefore, the energy storage device can store excess heat energy during the first period of sunlight to avoid energy waste, provide a heat source for the second period of sunlight, and release high-temperature sand particles during the second period of sunlight to ensure the continuous operation and stable output of the system.

[0033] In this embodiment, a fluidized bed 3 is connected to the outlet of the energy storage device and / or the outlet of the heating component. Gas is introduced into the fluidized bed 3, which acts as a fluidizing gas to keep the sand particles in a fluidized state, increasing the contact area and time between the gas and the sand particles. At the same time, it also acts as an energy storage medium, conducting efficient gas-solid heat exchange with the high-temperature sand particles. The high-temperature sand particles quickly transfer heat to the gas, completing the rapid energy release of the sand particles and the rapid energy storage of the gas. The stored gas can directly drive the subsequent combined power generation device.

[0034] Therefore, compared to traditional heat storage devices where sand particles are typically static, the heat transfer process is limited by the sand particle density and thermal conductivity, resulting in a low heat storage rate and significant heat loss. By innovatively utilizing fluidized bed 3 technology to introduce airflow and keep the sand particles in a fluidized state, a gas-solid two-phase flow is formed between the sand particles and the gas in fluidized bed 3. The fluidization of the sand particles ensures full contact between the gas and each sand particle, resulting in a heat exchange efficiency far exceeding that of statically packed heat exchangers 8. This avoids the adhesion and sintering phenomena that occur in statically heat-transferring sand particles, achieving both high-efficiency heat exchange and rapid heat transfer and release, thus improving response speed.

[0035] In this embodiment, in some cases, the fluidized bed 3 can be connected solely to the heating component. High-temperature sand particles are directly conveyed from the heating component to the fluidized bed 3 via pneumatic conveying. The high-temperature sand particles immediately undergo gas-solid heat exchange with the gas, rapidly increasing the gas temperature. This is suitable for scenarios where solar energy resources are abundant and immediate energy demand is high (such as peak power generation or heating). In some cases, the fluidized bed 3 can be connected solely to an energy storage device. The energy storage device releases stored high-temperature sand particles into the fluidized bed 3. This is suitable for utilizing thermal energy under conditions of insufficient sunlight or nighttime operation. In some cases, the fluidized bed 3 can be connected to both the heating component and the energy storage device simultaneously. High-temperature sand particles are directly conveyed from the heating component to the fluidized bed 3, while a portion of the high-temperature sand particles are simultaneously conveyed from the energy storage device to the fluidized bed 3, to meet the demand for rapid response during peak power or heating periods.

[0036] It can be seen that during the first and second illumination periods, the sand particles transported by the heating components or energy storage devices in the fluidized bed 3 undergo gas-solid heat exchange reactions.

[0037] It can be seen that the choice of the three connection methods can be achieved through the valves on the pipeline connecting the fluidized bed 3 to the heating components and the energy storage device.

[0038] The combined power generation unit is connected to the fluidized bed 3 to achieve thermoelectric conversion, converting the thermal energy of the heated gas output from the fluidized bed 3 into electrical energy. The high-temperature gas received in the combined power generation unit directly generates electricity through a turbine generator. The waste heat of the gas after power generation through turbine 5 is then used to generate electricity through steam turbine 7, realizing the cascade utilization of thermal energy and improving power generation efficiency. Finally, the waste heat of the steam after power generation through the steam turbine is used to heat the building, achieving full utilization of thermal energy.

[0039] In some embodiments, the low-temperature gas that has undergone multi-stage waste heat recovery can be returned to the fluidized bed 3 as a fluidized energy storage medium; and the steam that has undergone waste heat recovery can also be returned to the steam supply end of the turbine 7 (such as the heat exchanger 8) to realize the circulation of the steam required by the turbine 7.

[0040] In summary, this invention achieves high-quality and high-efficiency photoelectric conversion efficiency through multi-stage linkage of a concentrating solar collector 1, an energy storage device, a fluidized bed heat exchanger, and a combined power generation device. The heat storage temperature is high, reaching 900-1000℃, ultimately achieving a photoelectric conversion efficiency of approximately 32%. Furthermore, it utilizes the high specific heat capacity and high-temperature heat storage capacity of sand particles under dense-phase pneumatic transport conditions to achieve long-term stable storage of solar energy, which can be used for power generation or heating. The stored heat energy in the sand particles can be used for controllable heat release for power generation or heating during periods of user demand. The solar energy utilization efficiency can reach 35%, and the load of heat release for power generation can be adjusted, achieving effective utilization of solar energy. The system's preparation process is simple and easy to scale up, with low equipment system investment costs and great potential for large-scale utilization. In conclusion, this system solves the problems of inefficiency, instability, and poor thermal energy utilization response of traditional sand thermal storage technology.

[0041] As a preferred design in this embodiment, the heat carrier sand should have the highest possible specific heat capacity, greater than 1.1 KJ / (Kg℃), and the narrowest possible particle size distribution, with the average particle size controlled between 100 μm and 150 μm. Air is used as the gas and is delivered to the heating components or fluidized bed 3 by a fan.

[0042] In a further technical solution, the cold sand reflux assembly includes: a cold sand tank 4, which is connected to the heating assembly and the fluidized bed 3 respectively; and a first blower 15, which is connected to the cold sand tank 4 and is used to forcefully return the sand particles after gas-solid heat exchange output from the fluidized bed 3 to the heating assembly.

[0043] In this embodiment, the cold sand tank 4 is used to store sand particles output from the fluidized bed 3 after gas-solid heat exchange. The sand particles have completed heat transfer and temperature reduction, becoming cold sand. The cold sand tank 4 sends the cold sand back into the heating assembly through a return pipeline, where the sand particles are re-concentrated and heated, realizing the recycling of the sand particles. Specifically, the first blower 15 generates sufficient pneumatic force by blowing gas (such as air or other carrier gas) to pneumatically transport the cold sand in the cold sand tank 4 back to the heating assembly.

[0044] The first blower 15 can be a Roots blower. The outlet of the Roots blower is connected to the inlet of the cold sand tank 4 and the pipe connecting the outlet of the cold sand tank 4 to the heating element. This causes the gas output by the Roots blower to be divided into two streams. One stream blows the cold sand out of the cold sand tank 4, and the other stream, after the cold sand flows out of the cold sand tank 4, blows the cold sand out of the cold sand tank 4 back to the heating element.

[0045] Preferably, under pneumatic conveying conditions, the operating gas velocity is 0.89~4.47 m / s for dense phase pneumatic conveying, the gas-solid ratio is 20~50, and the bulk density is 200~2500 kg / m3.

[0046] Preferably, the cold sand tank 4 is located below the fluidized bed 3 and is connected to the fluidized bed 3 via a return pipe. Because the cold sand tank 4 is placed below the fluidized bed 3, the cold sand particles naturally fall from the fluidized bed 3 into the cold sand tank 4 within the return pipe due to their own fluidity and gravity after fluidization. This simplifies the complexity of sand particle return transport, eliminates the need for additional power equipment, and reduces system operating costs.

[0047] Furthermore, multiple heating components are provided, and the multiple heating components are sequentially connected; wherein, each heating component includes: a heat collection tube 12, the interior of which allows the sand particles to flow through; a grooved concentrator 11, the mirror surface of which is recessed to form a groove, and the heat collection tube 12 is disposed in the groove.

[0048] In this embodiment, multiple heating components can be connected in series and parallel to increase the overall heating capacity and improve efficiency. Preferably, the multiple heating components are connected sequentially, allowing sand grains to flow continuously between them. Each time a sand grain passes through a heating component, it absorbs more solar energy, gradually increasing its temperature. Therefore, multiple heating components increase the system's total heating capacity, thus supporting higher sand flow rates.

[0049] Several heating components share the same structure. Taking one component as an example, it includes a heat collection tube 12 and a trough-type concentrator 11. The heat collection tube 12 is made of glass, offering excellent light transmittance and high-temperature resistance. Its hollow interior forms a channel for sand flow, allowing sand to flow along the tube's length and receive concentrated solar heat. Simultaneously, the tube is kept in a vacuum state to minimize heat loss. The trough-type concentrator 11 has an arc-shaped mirror surface, with the upward-facing concave space forming a slot. Solar energy is concentrated at the slot through focused reflection, and the heat collection tube 12 is positioned within this slot, placing it at the focal point or concentrating line of the concentrator, maximizing solar thermal utilization and making it suitable for large-scale sand heating.

[0050] In some embodiments, the heat collection tube 12 can be a straight heat collection tube 12, an inclined heat collection tube 12, a curved heat collection tube 12, or an array of multiple heat collection tubes arranged in parallel.

[0051] Preferably, the heat collection tube 12 extends parallel to the length of the slot, and the extension length of the heat collection tube 12 is the same as the length of the slot; and the diameter of the heat collection tube 12 gradually decreases along the flow direction of the sand particles. In this embodiment, the heat collection tube 12 is arranged to extend parallel to the length of the slot, so that the focusing area of ​​the slot can cover the entire surface of the heat collection tube 12, making full use of the reflected light beam of the slot-type concentrator 11 to uniformly heat the sand particles inside the heat collection tube 12. The fact that the length of the slot is the same as the extension length of the heat collection tube 12 maximizes the utilization of the slot length, maximizes solar energy utilization, increases the amount of light energy absorbed per unit time, and achieves uniform heating of the particles to a temperature of 900-1000℃.

[0052] In some embodiments, such as Figure 2 and Figure 3 The heating assembly is shown in both perspective and front view. The collector tube 12 is mounted on the inner wall of the concentrator mirror via a pipe support 13, while the outer wall of the concentrator mirror is mounted to the ground or other base via a support 14. One or more pipe supports 13 can be provided along the length of the collector tube 12. The pipe support 13 consists of two rods extending obliquely from the outer wall of the collector tube 12 towards the concentrator mirror. The two rods, combined with the collector tube 12, form an inverted V-shaped structure, providing stable support while simplifying the structure.

[0053] Therefore, when the concentrating solar collector 1 is running, the air supplied by the Roots blower transports the cold sand in the cold sand tank 4 to the glass solar collector tube 12, so that the sand particles in the glass solar collector tube 12 are in a pneumatic conveying state. At this time, through the glass solar collector tube 12 and the trough concentrator 11, solar energy is used to heat the sand particles to 900~1000℃, and the continuous heating time is required to be 2~3 hours.

[0054] In a further technical solution, the energy storage device includes at least one thermal storage tank 2, each of the thermal storage tanks 2 being connected to the heating component and the fluidized bed 3 respectively; wherein, the outer periphery of each thermal storage tank 2 is covered with heat-insulating and fire-resistant insulation material.

[0055] In this embodiment, the thermal storage tank 2 exhibits excellent gas and particle sealing properties during heat storage. One or more storage tanks can be used, providing higher energy storage capacity and improving system flexibility and redundancy. The number of thermal storage tanks 2 can be flexibly expanded according to different application scales to meet varying energy demands. Thermal insulation and refractory materials are arranged around the thermal storage tank 2 to reduce heat loss from the high-temperature sand particles inside, thereby improving energy storage efficiency. Therefore, the temperature drop of the high-temperature particles inside the thermal storage tank 2 is less than 1°C / day.

[0056] Specifically, a feed valve is installed on the connecting pipe between the heating component and the heat storage tank 2. The feed valve is used to regulate and control the flow rate of sand particles from the heating component into the heat storage tank 2. Similarly, a discharge valve can be installed on the connecting pipe between the heat storage tank 2 and the fluidized bed 3. The discharge valve is used to regulate and control the flow rate of sand particles released from the heat storage tank 2 into the fluidized bed 3 to ensure that energy release matches demand.

[0057] This embodiment illustrates a fluidized heat exchanger, which includes a fluidized bed 3 and a cyclone separator connected to the fluidized bed 3 for removing impurities from the heated gas; and a second blower 16 connected to the fluidized bed 3 for feeding the gas into the fluidized bed 3.

[0058] In this embodiment, the cyclone separator generates centrifugal force through high-speed rotating airflow, separating solid particles (such as sand or other impurities) from the gas. In this system, the heated gas exiting the fluidized bed 3 is further purified by the cyclone separator to remove dust from the hot air, thus meeting the gas supply requirements of the combined power generation unit. The gas within the fluidized bed 3 is blown in by a second blower 16, providing a clean working fluid for the combined power generation unit. The second blower 16 maintains the speed and stability of the gas flow within the fluidized bed 3, ensuring that the sand particles remain fluidized under the influence of the airflow.

[0059] In some embodiments, the gas blown in by the second blower 16 can be the gas after it has completed its work, and the gas is circulated between the fluidized bed 3 and the combined power generation unit. The continuous heat exchange time of the gas-solid heat exchange process is 10-24 hours.

[0060] The fluidized bed 3 can be one or more of the following combined forms: gas-solid bubbling fluidized bed 3, gas-solid co-flow downward fluidized bed 3, and overflow pipe type multi-layer gas-solid fluidized bed 3.

[0061] Preferably, an overflow-pipe type multi-layer gas-solid fluidized bed 3 is adopted, i.e. Figure 4 The diagram shows a formal cross-sectional view of a multi-stage counter-current fluidized bed 3. The multi-stage counter-current fluidized bed 3 includes an air outlet 32 ​​located at the center of the bed top for discharging hot air after gas-solid heat exchange; a sand inlet 33 located on the side of the bed top for inputting heated high-temperature particles; an air inlet 31 located at the center of the bed bottom for introducing air; and a sand outlet 34 located on the side of the bed bottom for discharging cold sand after gas-solid heat exchange. Therefore, air and high-temperature sand particles flow in opposite directions within the fluidized bed 3, improving heat exchange uniformity.

[0062] This embodiment illustrates a combined power generation device. The combined power generation device includes, in sequence: a turbine generator connected to the fluidized bed 3, used to generate electricity using the heated gas; a steam turbine generator set connected to the turbine generator via a heat exchanger set 8, used to heat water to form steam using the waste heat of the gas discharged from the turbine generator, and to generate electricity using the steam; and a heating terminal connected to the steam turbine generator set via a heat exchanger 8, used to provide heating using the waste heat of the steam discharged from the steam turbine generator set.

[0063] In this embodiment, please refer again. Figure 1 The turbine generator (usually a combination of turbine 5 and generator 6) primarily uses the thermal energy of gas to drive turbine 5, which in turn drives generator 6 to generate electricity. The gas, heated after passing through fluidized bed 3, possesses high thermal energy. This high-temperature air is first used to power turbine 5, directly driving it to generate electricity, rapidly utilizing high-quality thermal energy and improving response speed. After the air has done work in turbine 5, its temperature decreases, but it still contains a significant amount of waste heat. This waste heat can be used to heat water to produce steam, which drives a steam turbine unit (usually a combination of steam turbine 7 and generator 6) for secondary power generation, achieving cascaded energy utilization. The remaining heat from the steam is used to heat the heating terminals (such as condenser 10) through heat exchanger 8, further improving the overall system efficiency. Finally, the gas, still carrying a small amount of waste heat, recirculates back into fluidized bed 3. Therefore, this combined power generation system utilizes solar-heated gas, waste heat from the gas, and waste heat from the steam, providing electricity and heat to users through an efficient energy conversion process, possessing multiple advantages such as high efficiency, energy saving, and environmental protection.

[0064] Heating terminals include water heaters, heating systems, and hot air systems.

[0065] Furthermore, the heat exchanger 8 is connected to the heat exchanger group 8 via a water pump 9, which is used to circulate water after waste heat utilization into the heat exchanger group 8; and the heat exchanger group 8 is connected to the fluidized bed 3 via the second blower 16, which is used to circulate gas after work into the fluidized bed 3.

[0066] Therefore, the water vapor after waste heat utilization condenses and is pumped into heat exchanger group 8 via water pump 9, where it absorbs waste heat from the gas again to form steam, completing the water cycle. Simultaneously, the gas after waste heat utilization in heat exchanger group 8 is sent back to fluidized bed 3 for recycling via second blower 16. Through the recycling of water and gas, the system can efficiently recover and utilize heat, improving the energy efficiency of the entire thermoelectric conversion system. Furthermore, through gas recirculation, the remaining heat in the gas after work can be used for further gas-solid heat exchange, increasing the thermal energy conversion rate.

[0067] It is understandable that a steam turbine unit can be a combination of one or more steam turbines 7 and generators 6 to achieve multi-stage thermal energy gradient utilization.

[0068] Please see Figure 5 , Figure 5 A flowchart illustrating the steps of the high-heat-release thermoelectric conversion method for sand energy storage according to the present invention is shown. The method relies on the high-efficiency and high-quality thermoelectric conversion system for sand energy storage provided above for thermoelectric conversion. The method includes the following steps: S1. During the first period of sunlight, the heating component is used to concentrate solar energy onto the sand grains to heat them; that is, when there is sufficient sunlight, the solar concentrating and heat collection device 1 is set to pneumatic conveying mode, and the solar energy is used to quickly and continuously charge the heating component to heat the heat carrier sand grains to 900~1000℃, thus completing the charging process.

[0069] S2. The heated sand particles are introduced into the energy storage device and the fluidized heat exchanger respectively, and the energy storage device is used to store the sand particles; the heated heat carrier sand particles in the heating component are continuously introduced into the heat storage tank 2 to realize the storage of thermal energy.

[0070] S3. During the second period of sunlight, the high-temperature sand particles stored in the energy storage device are released into the fluidized heat exchange device; when sunlight is insufficient, the sand particles in the heat storage tank 2 are continuously introduced into the fluidized bed 3.

[0071] S4. The sand particles are fluidized using the gas in the fluidized heat exchanger and gas-solid heat exchange is performed with the fluidized sand particles to heat the gas; during the first and second illumination periods, when enough sand particles are received in the fluidized bed 3, the sand particles are fluidized using air as a working fluid, thereby simultaneously heating the air and releasing heat from the sand particles.

[0072] S5. The heated gas is introduced into the combined power generation unit to generate electricity using the thermal energy of the gas; hot air working fluid is introduced into the combined power generation unit to achieve continuous power generation in the combination of turbine generator and steam turbine generator set.

[0073] Furthermore, after step S5, the following steps are also included: S6. The sand particles after gas-solid heat exchange are transported to the cold sand tank 4, and the sand particles are returned to the heating component by the first blower 15 to complete the circulation of sand particles. S7. The gas that has completed its work is returned to the fluidized bed 3 through the second blower 16 to complete the gas circulation.

[0074] As the method embodiments are basically similar to the system embodiments, the description is relatively simple, and relevant parts can be found in the description of the method embodiments.

[0075] The present invention will be further illustrated below through several specific embodiments: Example 1: A high-heat-release thermoelectric conversion method for sand energy storage involves a trough-type concentrator 11 focusing light energy onto the surface of a glass heat collector tube 12 within the trough of the concentrator 11. Inside the glass heat collector tube 12, sand particles with an average particle size of 150 μm and a narrow sieve diameter flow. The sand is heated by the light energy, and 15 tons of sand are heated within 2 hours. The sand reaches a temperature of 900°C at the device outlet and flows into the heat storage tank 2 through pipelines, with an apparent gas velocity of 3.5 m / s inside the tubes.

[0076] Close the feed valve of thermal storage tank 2 and open the discharge valve of thermal storage tank 2, allowing the hot sand particles to flow into the fluidized bed 3 below. Depending on user requirements, heat is continuously released over 10 hours, raising the air pressure temperature to 800℃, which is then used by the turbine generator to supply electricity to the user.

[0077] Example 2: A high-heat-release thermoelectric conversion method for sand energy storage involves a trough-type concentrator 11 focusing light energy onto the surface of a glass heat collector tube 12 within the trough of the concentrator 11. Inside the glass heat collector tube 12, sand particles with an average particle size of 100 μm and a narrow sieve diameter flow. The sand is heated by the light energy, and 15 tons of sand are heated within 2 hours. The sand reaches a temperature of 900°C at the device outlet and flows into the heat storage tank 2 through pipelines, with an apparent gas velocity of 3.5 m / s inside the tubes.

[0078] Close the feed valve of thermal storage tank 2 and open the discharge valve of thermal storage tank 2, allowing the hot sand particles to flow into the fluidized bed 3 below. According to user requirements, heat is continuously released over 12 hours, raising the air pressure temperature to 750℃, which is then used by the turbine generator to supply electricity to the user.

[0079] Example 3: A high-heat-release thermoelectric conversion method for sand energy storage involves a trough-type concentrator 11 focusing light energy onto the surface of a glass heat collector tube 12 within the trough of the concentrator 11. Inside the glass heat collector tube 12, sand particles with an average particle size of 120 μm and a narrow sieve diameter flow. The sand is heated by the light energy, and 15 tons of sand are heated within 2 hours. The sand reaches a temperature of 900°C at the device outlet and flows into the heat storage tank 2 through pipelines, with an apparent gas velocity of 2.5 m / s inside the tubes.

[0080] Close the feed valve of thermal storage tank 2 and open the discharge valve of thermal storage tank 2, allowing the hot sand particles to flow into the fluidized bed 3 below. According to user requirements, heat is continuously released over 8 hours, raising the air pressure temperature to 850℃, which is then used by the turbine generator to supply electricity to the user.

[0081] In summary, the efficient and high-quality thermoelectric conversion system and method for sand energy storage provided by this invention utilizes the high photothermal conversion rate, the high specific heat capacity of sand, and its ability to store heat at high temperatures to achieve long-term stable storage of renewable intermittent energy. It also enables controlled heat release for power generation or heating. The system combines a trough-type solar concentrator and a fluidized bed heat exchanger, and its fabrication process is simple and easy to scale up. Furthermore, the system has low investment costs, the sand is recyclable, and its service life is several decades, demonstrating a very broad prospect in energy storage technology.

[0082] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of this application.

[0083] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0084] It should also be noted that, in this document, the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations, nor should they be construed as indicating or implying relative importance. Moreover, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements, but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device.

[0085] The above provides a detailed description of a high-efficiency and high-quality thermoelectric conversion system and method for sand energy storage provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand this application, and the content of this specification should not be construed as a limitation of this application. Furthermore, for those skilled in the art, there will be different variations in the specific implementation methods and application scope based on this application. It is neither necessary nor possible to exhaustively list all implementation methods here, and any obvious variations or modifications derived therefrom are still within the protection scope of this application.

Claims

1. A sand energy efficient high-quality thermoelectric conversion system, characterized by, The system includes: A solar concentrator includes a heating component and a cold sand recirculation component that are interconnected. The heating component contains sand grains and is used to concentrate solar energy onto the sand grains. The cold sand recirculation component is used to provide the heating component with the aerodynamic force that drives the sand grains to flow; The cold sand reflux assembly includes: a cold sand tank, which is connected to the heating assembly and the fluidized bed respectively; and a first blower, which is connected to the cold sand tank and is used to forcefully return the sand particles after gas-solid heat exchange output from the fluidized bed to the heating assembly. The heating components are provided in multiple ways and are connected in sequence; each heating component includes: a glass heat collection tube, through which the sand particles can flow; a groove-type concentrating mirror, the mirror surface of which is recessed to form a groove, the glass heat collection tube being installed in the groove through a pipe support; the glass heat collection tube extends along a length direction parallel to the groove, and the diameter of the glass heat collection tube gradually decreases, the extension length of the glass heat collection tube being the same as the length of the groove; The glass heat collector tube is in a vacuum state; the pipe support consists of two rods that extend obliquely from the outer wall of the glass heat collector tube toward the trough-type concentrating mirror, and the two rods and the glass heat collector tube form an inverted V-shaped structure. An energy storage device includes at least one thermal storage tank, each of which is connected to the heating component and the fluidized bed, for storing or releasing the solar-heated sand particles at different light periods; wherein, the outer periphery of each thermal storage tank is covered with a heat-insulating and fire-resistant insulation material, which is used to maintain the temperature of the sand particles inside the thermal storage tank. A fluidized bed heat exchanger includes a fluidized bed, a cyclone separator and a second blower connected to the fluidized bed, the second blower being used to input gas into the fluidized bed; wherein the fluidized bed is connected to the heating component and / or the energy storage device, and is used to fluidize the received sand particles using the gas, and to perform gas-solid heat exchange with the fluidized sand particles to heat the gas; the cyclone separator is used to remove impurities from the heated gas; the fluidized bed is an overflow-pipe type multi-layer gas-solid fluidized bed, including an air outlet located at the center of the top of the bed, a sand particle inlet located on the side of the top of the bed, an air inlet located at the center of the bottom of the bed, and a sand particle outlet located on the side of the bottom of the bed, wherein air and high-temperature sand particles flow in opposite directions within the fluidized bed; Combined power generation units, including those connected in sequence: A turbine generator, connected to the fluidized bed, is used to generate electricity using the heated gas. A steam turbine generator set is connected to the turbine generator via a heat exchanger set, and is used to heat water to form steam by utilizing the waste heat of the gas discharged from the turbine generator, and to generate electricity through the steam. The heating terminal is connected to the steam turbine generator set via a heat exchanger and is used to provide heating by utilizing the waste heat of the steam discharged from the steam turbine generator set. The heat exchanger is connected to the heat exchanger group via a water pump, which is used to circulate water after waste heat utilization into the heat exchanger group; and the heat exchanger group is connected to the fluidized bed via the second blower, which is used to circulate gas after work is done into the fluidized bed.

2. The high-efficiency and high-quality thermoelectric conversion system for sand energy storage according to claim 1, characterized in that, The cold sand tank is located below the fluidized bed and is connected to the fluidized bed through a reflux pipe.

3. A high-heat-release thermoelectric conversion method for sand energy storage, characterized in that, Thermoelectric conversion is performed using the high-efficiency and high-quality thermoelectric conversion system for sand storage as described in any one of claims 1-2, and the method includes: During the first period of sunlight, solar energy is concentrated onto the sand grains using a heating component to heat the sand grains. The heated sand particles are introduced into an energy storage device and a fluidized heat exchanger, respectively, and the energy storage device is used to store the sand particles. During the second period of illumination, the high-temperature sand particles stored in the energy storage device are released into the fluidized heat exchanger. The sand particles are fluidized by the gas in the fluidized heat exchanger, and gas-solid heat exchange is performed between the fluidized sand particles to heat the gas. The heated gas is introduced into a combined power generation unit, and the thermal energy of the gas is used to generate electricity.

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