Heat energy recovery and utilization system based on low-grade heat energy

Abstract

According to the heat energy recovery and utilization system based on the low-grade heat energy, the heat storage particles in the heat storage subsystem are used for heating the first heat carrier from the temperature lower than 150 DEG C to the temperature of 1000-1500 DEG C, so that the grade of the heat energy is remarkably improved, and the heat energy can be directly used for high-grade heat energy demand scenes such as industrial production or building heating; and the utilization value and economical efficiency of low-grade heat energy are greatly improved. And compared with a traditional sensible heat storage material, the overall efficiency of heat energy recovery is improved through the efficient heating mode of the heat storage particles.

Description

Technical Field

[0001] The present application relates to the technical field of heat energy recovery and utilization, and in particular to a heat energy recovery and utilization system based on low-grade heat energy. Background Art

[0002] The waste of low-temperature thermal energy (e.g., waste heat below 150°C) is becoming increasingly prominent in current industrial production, building heating, and renewable energy utilization. Although this low-temperature thermal energy is readily available and readily available, its low quality makes direct use less economical and efficient, leading to numerous technical challenges in its recovery.

[0003] Existing low-temperature heat energy recovery and storage technologies mostly rely on direct heat exchange or low-efficiency heat pump technology, which have obvious limitations in recovery efficiency. Summary of the Invention

[0004] To address these issues, the present invention provides a heat recovery and utilization system based on low-grade thermal energy. This system uses thermal storage particles in the thermal storage subsystem to heat the first heat carrier from below 150°C to 1000°C–1500°C, significantly improving the quality of the thermal energy. This allows it to be directly used in high-quality thermal energy demand scenarios such as industrial production or building heating, significantly increasing the utilization value and economic efficiency of low-grade thermal energy. Furthermore, compared to traditional sensible heat storage materials, the present invention improves the overall efficiency of heat recovery through the efficient heating of the thermal storage particles.

[0005] The present invention provides a heat energy recovery and utilization system based on low-grade heat energy, the system comprising a low-grade heat energy storage subsystem (1), a heat storage subsystem (2) and a heat utilization subsystem (3) connected in sequence; The outlet of the low-grade thermal energy storage subsystem (1) is connected to the inlet of the heat storage subsystem (2), and the low-grade thermal energy storage subsystem (1) is configured to store a first heat carrier and transport the first heat carrier to the heat storage subsystem (2); The outlet of the heat storage subsystem (2) is connected to the inlet of the heat-using subsystem (3); the heat storage subsystem stores heat storage particles; the heat storage subsystem (2) is configured to heat the first heat carrier with the heat storage particles to absorb heat to form a second heat carrier, and to transport the second heat carrier to the heat-using subsystem (3); The heat-using subsystem (3) is configured to consume the heat of the second heat carrier, cool the heat carrier, and form a third heat carrier; Wherein, the temperature of the second heat carrier is 1000 ℃~1500 ℃; The first heat carrier is one of air, nitrogen, carbon dioxide, flue gas and water vapor carrying low-grade thermal energy, and the temperature of the first heat carrier is not higher than 150°C.

[0006] Optionally, the outlet of the heat-using subsystem (3) is connected to the inlet of the heat-storage subsystem (2); The heat-using subsystem (3) is further configured to transport the third heat carrier to the heat storage subsystem (2) for heating.

[0007] Optionally, the low-grade thermal energy is one of industrial low-temperature waste heat, low-temperature geothermal energy and seawater heat.

[0008] Optionally, the heat storage subsystem (2) includes a heat storage device (21) and a heating device (22); The inlet of the heat storage device (21) is connected to the outlet of the low-grade thermal energy storage subsystem (1), and the outlet of the heat storage device (21) is connected to the inlet of the heat-using subsystem (3). The heat storage device (21) is configured to store the heat storage particles and transport the second heat carrier particles to the heat-using subsystem (3); The heating device (22) is connected to the heat storage device (21), and the heating device (22) is used to heat the heat storage particles.

[0009] Optionally, the heat storage particles have a particle size of less than 2 cm and a melting point greater than 2000°C.

[0010] Optionally, the heating device (22) is a resistance heater or an electromagnetic induction heater; The heating device (22) is powered by wind energy or solar energy.

[0011] Optionally, the system further comprises a gas tank (4); The gas tank (4) comprises a first input port (41) and a second input port (42); wherein the first input port (41) is connected to the outlet of the low-grade thermal energy storage subsystem (1), the second input port (42) is connected to the outlet of the heat-using subsystem (3), and the outlet of the gas tank (4) is connected to the heat storage subsystem (2); The gas tank (4) is configured to mix the first heat carrier and the third heat carrier, and then transport them to the heat storage subsystem (2).

[0012] Optionally, a heat-insulating layer is provided on the gas tank (4).

[0013] Optionally, the system further comprises a fan (5), wherein an air inlet end of the fan (5) is connected to the outlet of the heat-using subsystem (3), and an air outlet end of the fan (5) is connected to the second input port (42) of the gas tank (4); The fan (5) is configured to blow the third heat carrier into the gas tank (4).

[0014] Optionally, a heat pump (6) is provided on the low-grade thermal energy storage subsystem (1); The heat pump (6) is configured to heat a first heat carrier in the low-grade thermal energy storage subsystem (1) with a temperature less than 50°C.

[0015] Beneficial effects: This invention provides a heat recovery and utilization system based on low-grade thermal energy. This system utilizes heat storage particles in a heat storage subsystem to heat low-grade thermal energy below 150°C to 1000°C–1500°C, significantly improving the quality of the thermal energy. This high-temperature thermal energy can be more efficiently utilized in industrial production, building heating, and other scenarios, addressing the low efficiency of direct utilization of low-grade thermal energy.

[0016] This invention uses thermal storage particles as an energy storage medium to store heat from the energy storage subsystem and transfer it to the first heat carrier, avoiding the direct storage of low-grade thermal energy using the thermal storage medium and achieving more efficient heat recovery. The thermal storage particles used in this invention have a higher heat capacity and better thermal insulation properties, effectively reducing energy loss during storage and improving energy storage efficiency.

[0017] Compared with the poor economic efficiency of traditional low-grade thermal energy recovery and utilization, the present invention reduces the recovery cost of unit thermal energy through efficient thermal energy enhancement and energy storage technology, thereby improving the economy of the overall system, helping to promote the commercial application of low-grade thermal energy, providing a technical basis for the large-scale utilization of low-temperature thermal energy, reducing energy waste, and promoting the efficient use of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] Figure 1 A schematic diagram of the structure of a heat energy recovery and utilization system based on low-grade heat energy proposed in an embodiment of the present application is shown; Figure 2 A schematic diagram of the structure of another heat recovery and utilization system based on low-grade heat energy proposed in an embodiment of the present application is shown; Figure 3 A schematic diagram of the structure of a gas tank in a heat energy recovery and utilization system based on low-grade heat energy proposed in an embodiment of the present application is shown; Figure 4 A schematic diagram of the structure of a fan in a heat energy recovery and utilization system based on low-grade heat energy proposed in an embodiment of the present application is shown; Figure 5 A schematic diagram of the structure of a heat pump in a heat energy recovery and utilization system based on low-grade thermal energy proposed in an embodiment of the present application is shown.

[0020] Description of reference numerals: 1. Low-grade thermal energy storage subsystem; 2. Heat storage subsystem; 21. Heat storage device; 22. Heating device; 3. Heat subsystem; 4. Gas tank; 41. First input port; 42. Second input port; 5. Fan; 6. Heat pump. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] In the drawings, the sizes of components, layer thicknesses, or regions may be exaggerated for clarity. Therefore, any implementation of the present disclosure is not necessarily limited to the dimensions shown in the drawings, and the shapes and sizes of components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate idealized examples, and any implementation of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0023] Among related technologies, efficient and sustainable energy utilization is a key global challenge. In industrial production, building heating, and renewable energy utilization, a significant amount of low-temperature thermal energy (e.g., waste heat or residual heat below 150°C) is wasted. While this low-temperature thermal energy is readily available and readily available, its low quality makes direct utilization uneconomical and inefficient, leading to numerous technical challenges in its recovery.

[0024] Existing low-temperature heat recovery and storage technologies mostly rely on direct heat exchange or inefficient heat pump technology, resulting in limited recovery efficiency. Furthermore, traditional sensible heat storage materials (such as water or rock) have low thermal capacity and insufficient thermal insulation, resulting in significant energy losses during the storage of low-grade thermal energy. Furthermore, many thermal storage technologies fail to fully consider the need for high-grade thermal energy conversion during design, resulting in a single form of thermal energy utilization that is difficult to meet in high-end applications such as industrial heating or power generation. More importantly, current low-temperature heat recovery and storage systems are mostly separate designs, lacking an efficient integrated overall solution. The resulting complex system equipment and high operating energy consumption restrict their large-scale application and promotion.

[0025] Based on the content of related technology, the present invention provides a heat recovery and utilization system based on low-grade heat energy, see Figure 1 , the system comprises a low-grade thermal energy storage subsystem 1, a heat storage subsystem 2 and a heat utilization subsystem 3 connected in sequence; The outlet of the low-grade thermal energy storage subsystem 1 is connected to the inlet of the heat storage subsystem 2. The low-grade thermal energy storage subsystem 1 is configured to store a first heat carrier and transport the first heat carrier to the heat storage subsystem 2. The outlet of the heat storage subsystem 2 is connected to the inlet of the heat-using subsystem 3. The heat storage subsystem 2 stores heat storage particles. The heat storage subsystem 2 is configured to heat the first heat carrier with the heat storage particles to absorb heat to form a second heat carrier, and then transport the second heat carrier to the heat-using subsystem 3. The heat using subsystem 3 is configured to consume the heat of the second heat carrier, cool the heat carrier, and form a third heat carrier; Wherein, the temperature of the second heat carrier is 1000 ℃~1500 ℃; The first heat carrier is one of air, nitrogen, carbon dioxide, flue gas and water vapor carrying low-grade thermal energy, and the temperature of the first heat carrier is not higher than 150°C.

[0026] It should be noted that low-grade thermal energy refers to the heat carried by heat carriers with a temperature below 150°C; The low-grade thermal energy storage subsystem 1 refers to a closed container capable of transporting and / or storing low-grade thermal energy; Heat carriers refer to fluids that can carry heat. Air and nitrogen are suitable for high-temperature environments and are relatively low-cost. Carbon dioxide has good thermal conductivity at high temperatures and is suitable for scenarios requiring efficient heat transfer. Water vapor is suitable for industrial processes requiring steam. The low-grade thermal energy storage subsystem 1 may also be provided with an inlet to transport the first heat carrier into the low-grade thermal energy storage subsystem 1 for storage, thereby ensuring that the system can operate continuously; The outlet of the low-grade thermal energy storage subsystem 1 and the inlet of the heat storage subsystem 2 may be connected via a pipeline; The heat storage subsystem 2 is a system that can heat and preserve the heat storage particles, and can also allow the first heat carrier to pass through and exchange heat with the heat storage particles; The outlet of the heat storage subsystem 2 and the inlet of the heat use subsystem 3 can be connected by a pipeline; The heat storage particles can be made of materials with high specific heat capacity, such as ceramics, metal oxides, or composite materials. The heat storage particles provided by the present invention have high thermal conductivity and good thermal stability, can operate stably at high temperatures, and can maintain their performance after multiple heating and cooling cycles. The temperature of the second heat carrier may be 1000°C, 1100°C, 1200°C, 1300°C, 1400°C or 1500°C; Heat-using subsystem 3 refers to systems, equipment, or other user terminals that require heat or other heating needs; for example, industrial production, building heating, etc. The heat-using subsystem 3 is configured to consume the heat of the heated heat carrier, which means that the heat-using subsystem 3 absorbs the heat of the second heat carrier, causing the second heat carrier to release heat and cool down, thereby realizing heat transfer; In specific implementation, the first heat carrier with a temperature below 150°C in the low-grade thermal energy storage subsystem 1 is discharged along the outlet of the low-grade thermal energy storage subsystem 1, and then enters the heat storage subsystem 2 through the inlet of the heat storage subsystem 2, contacts the heat storage particles, and the heat storage particles heat the first heat carrier with a temperature below 150°C. After the first heat carrier absorbs heat, a second heat carrier with a temperature of 1000°C to 1500°C is obtained, and the heat storage particles cool down; the second heat carrier is discharged along the outlet of the heat storage subsystem 2, and then enters the heat-using subsystem 3 through the inlet of the heat-using subsystem 3, providing heat to the heat-using subsystem 3, and the second heat carrier cools down after releasing heat.

[0027] In this invention, by providing a heat storage subsystem 2, heat storage particles are used to elevate the originally low-grade thermal energy of the first heat carrier (below 150°C) to high-temperature heat energy of 1000°C to 1500°C. Compared to traditional methods, using a heat storage medium to store low-grade thermal energy offers higher thermal energy utilization efficiency and avoids heat waste during storage. The resulting high-temperature thermal energy (i.e., the heat energy carried by the second heat carrier) can be directly used for industrial production or building heating, significantly improving the efficiency and cost-effectiveness of low-grade thermal energy. By converting low-grade thermal energy into high-temperature thermal energy, this invention facilitates the large-scale utilization of low-temperature thermal energy, thereby reducing energy waste, lowering dependence on traditional energy sources, and promoting the widespread use of renewable energy.

[0028] In practice, the first heat carrier in this invention can be selected from air, nitrogen, carbon dioxide, flue gas, or water vapor. These carriers all offer excellent thermal conductivity in different application scenarios. For example, air and nitrogen are suitable for high-temperature environments, while water vapor is suitable for industrial processes requiring steam. This flexibility enables the system to adapt to a variety of industrial needs.

[0029] In some embodiments, the low-grade thermal energy is one of industrial low-temperature waste heat, low-temperature geothermal heat and seawater heat.

[0030] It should be noted that industrial low-temperature waste heat refers to low-temperature exhaust gas from the metal and chemical industries after heat use, with the exhaust gas temperature below 150°C. Low-temperature geothermal energy or seawater heat can be used as low-grade heat sources. However, since the heat generation temperature of low-temperature geothermal energy and seawater heat is not high, generally below 150°C, the heat after use cannot be recovered and is wasted. Therefore, they can be used as low-quality heat sources. The system provided by the present invention can be connected to geothermal resources through geothermal wells to recycle and utilize this part of the heat energy.

[0031] In specific implementation, the first heat carrier can be obtained through heat exchange from any one of industrial low-temperature waste heat, low-temperature geothermal heat and seawater heat, or the first heat carrier can be generated by the utilization process of industrial low-temperature waste heat, low-temperature geothermal heat and seawater heat; or the thermal energy of industrial low-temperature waste heat, low-temperature geothermal heat and seawater heat itself is stored or embodied in the form of the first heat carrier.

[0032] In the present invention, the sources of low-grade thermal energy include a variety of common heat sources such as industrial low-temperature waste heat, low-temperature geothermal energy and seawater heat. This diversity enables the system to adapt to the heat recovery needs of different scenarios, thereby improving the universality and application scope of the technology. In implementation, industrial low-temperature waste heat, low-temperature geothermal energy and seawater heat are regarded as energy sources that are difficult to use efficiently. By integrating these low-grade thermal energies into the system, the present invention realizes the effective recovery and utilization of these resources and reduces energy waste. By recycling industrial low-temperature waste heat and utilizing low-temperature geothermal energy and seawater heat, it is possible to reduce dependence on traditional fossil energy, reduce greenhouse gas emissions, and meet the goal of sustainable development.

[0033] In practice, the system provided by the present invention can achieve switching between different low-grade heat sources through modular design and intelligent control. For example, by providing valves and pipelines in the low-grade thermal energy storage subsystem 1, different low-grade thermal energy can be flexibly selected and input into the low-grade thermal energy storage subsystem 1 through adjustment.

[0034] In some embodiments, see Figure 2 , the outlet of the heat-using subsystem 3 is connected to the inlet of the heat storage subsystem 2; The heat utilization subsystem 3 is further configured to transport the third heat carrier to the heat storage subsystem 2 for heating.

[0035] It should be noted that the outlet of the heat-using subsystem 3 and the inlet of the heat-storage subsystem 2 can be connected by a pipeline; The third heat carrier is generated because the heat storage subsystem 2 delivers the second heat carrier to the heat using subsystem 3, which consumes the heat carried by the second heat carrier, cooling the second heat carrier to below 50°C, thereby obtaining the third heat carrier. The third heat carrier still carries a small amount of heat. The third heat carrier is then transported to the heat storage subsystem 2, where it is heated by the heat storage particles and can continue to provide heat to the heat-using subsystem 3, thus realizing the recycling of resources. The first heat carrier, the second heat carrier and the third heat carrier differ only in temperature.

[0036] In specific implementation, after the heat of the second heat carrier is consumed by the heat-using subsystem 3, the second heat carrier is cooled to below 50°C to obtain a third heat carrier; the third heat carrier is discharged along the outlet of the heat-using subsystem 3 and then transported to the heat storage subsystem 2 along the inlet of the heat storage subsystem 2. The third heat carrier with a temperature less than 50°C is heated by heat storage particles to 1000°C~1500°C, and then the heated third heat carrier is transported to the heat-using subsystem 3 for heating.

[0037] In the present invention, the outlet of the heat-using subsystem 3 is connected to the inlet of the heat storage subsystem 2 to realize the recycling of the second heat carrier. After the heat-using subsystem 3 consumes the heat of the second heat carrier, the third heat carrier with a temperature below 50°C is re-transported to the heat storage subsystem 2 for heating, forming a closed-loop system, thereby significantly improving the overall thermal energy utilization efficiency of the system. In traditional systems, heat carriers are often directly discharged or cooled after use, resulting in a large amount of unrecovered low-temperature heat energy being wasted. The present invention avoids the loss of this part of energy by reheating the third heat carrier, thereby improving the overall energy utilization efficiency of the system and reducing the waste of heat energy and heat carriers. Since the heat carrier in the present invention can be recycled, the need for external heat carrier replenishment is reduced, thereby reducing the operating cost of the system. In addition, recycling can also reduce thermal pollution to the environment, which is in line with the development trend of green energy.

[0038] In some embodiments, see Figure 1 , the heat storage subsystem 2 includes a heat storage device 21 and a heating device 22; The inlet of the heat storage device 21 is connected to the outlet of the low-grade thermal energy storage subsystem 1, and the outlet of the heat storage device 21 is connected to the inlet of the heat-using subsystem 3. The heat storage device 21 is configured to store the heat storage particles and transport the second heat carrier to the heat-using subsystem 3; The heating device 22 is connected to the heat storage device 21 , and the heating device 22 is used to heat the heat storage particles.

[0039] It should be noted that the inlet of the heat storage device 21 and the outlet of the low-grade thermal energy storage subsystem 1 may be connected via a pipeline; The outlet of the heat storage device 21 and the inlet of the heat-using subsystem 3 may be connected by a pipeline; The heat storage device 21 is a sealed container filled with heat storage particles. The heat storage device 21 can be made of multiple layers of heat insulation materials to reduce heat loss. During specific implementation, the heating device 22 is first started, and the heating device 22 heats the heat storage particles to 1500℃~2000℃. Then, the low-grade thermal energy storage subsystem 1 discharges the first heat carrier along the outlet, and the first heat carrier enters through the inlet of the heat storage device 21. The heat storage particles release heat and then cool down. The first heat carrier absorbs heat and then heats up to 1000℃~1500℃ to obtain the second heat carrier. The second heat carrier is then discharged along the outlet of the heat storage device 21 and then enters through the inlet of the heat-using subsystem 3 to provide heat for the heat-using subsystem 3.

[0040] In this invention, by arranging a heat storage device 21 and a heating device 22 to work together, the system can efficiently convert low-grade thermal energy (a first heat carrier below 150°C) into high-temperature thermal energy (a second heat carrier between 1000°C and 1500°C), solving the problems of low thermal capacity and poor thermal insulation performance associated with traditional sensible heat storage materials. The separate configuration of the heat storage device 21 and the heating device 22 allows the system to flexibly manage the storage and release of thermal energy. The heating device 22 can heat the thermal storage particles as needed, while the heat storage device 21 is responsible for storing and releasing thermal energy, thereby improving the system's operational flexibility and responsiveness.

[0041] In some embodiments, the heat storage particles have a particle size of less than 2 cm and a melting point greater than 2000°C.

[0042] It should be noted that the heat storage particles can be aluminum oxide, silicon carbide, magnesium oxide, zirconium oxide, etc. The particle size of the heat storage particles can be 0.1 cm, 0.5 cm, 1 cm, 1.5 cm, and 1.8 cm.

[0043] In this invention, the thermal storage particles, with a particle size of less than 2 cm, have a large surface area, which facilitates high heat exchange efficiency between the first heat carrier and the thermal storage particles. This allows for faster and more uniform transfer of heat energy, thereby improving the overall thermal efficiency of the system. The thermal storage particles have a melting point greater than 2000°C, ensuring their stability in high-temperature environments. Even during heating at temperatures between 1000°C and 1500°C, the thermal storage particles do not melt or deform, thus ensuring long-term stable operation of the system.

[0044] In some embodiments, see Figure 2 When the energy storage subsystem includes a heat storage device 21 and a heating device 22, the outlet of the heat subsystem 3 is connected to the heat storage device 21 to facilitate the transportation of the third heat carrier to the heat storage device 21 for heating using the heat storage particles.

[0045] In some embodiments, see Figure 1 , the heating device 22 is a resistance heater or an electromagnetic induction heater; The heating device 22 is powered by wind energy or solar energy.

[0046] It should be noted that a resistance heater refers to a device that efficiently converts electrical energy into thermal energy through the Joule heating principle; Electromagnetic induction heater refers to a heating controller based on the principle of electromagnetic induction heating. When working, the alternating current generates an induced current in the conductor. The induced current overcomes the resistance of the conductor itself, generates Joule heat, and heats the conductor. Wind power supply refers to the process of converting wind energy into electrical energy and then transmitting the electrical energy to the heating device 22; Solar power supply refers to the process of using solar energy to convert light energy into electrical energy and then transmitting the electrical energy to the heating device 22.

[0047] In the present invention, both a resistance heater and an electromagnetic induction heater are highly efficient heating devices 22, capable of rapidly heating the heat storage particles to temperatures ranging from 1000°C to 1500°C. The resistance heater directly heats the particles using an electric current, while the electromagnetic induction heater generates eddy currents within the particles through an electromagnetic field. Both are highly efficient and controllable. Heating device 22 is powered by wind or solar energy, reducing reliance on traditional fossil energy and lowering the system's carbon emissions. This aligns with the development of green energy and enhances the system's sustainability and environmental friendliness.

[0048] In a specific implementation, in order to ensure the stable operation of the heating device 22, an energy storage system may be further provided in the system provided by the present invention; An energy storage system can be connected to the heating device 22 to provide power; for example, a battery or a supercapacitor to balance the intermittent supply of wind and solar energy.

[0049] In some embodiments, see Figure 3 , the system further comprises a gas tank 4; The gas tank 4 includes a first input port 41 and a third input port; wherein the first input port 41 is connected to the outlet of the low-grade thermal energy storage subsystem 1, the third input port is connected to the outlet of the heat utilization subsystem 3, and the outlet of the gas tank 4 is connected to the heat storage subsystem 2; The gas tank 4 is configured to mix the first heat carrier and the third heat carrier, and then transport the mixed mixture to the heat storage subsystem 2 .

[0050] It should be noted that the first input port 41 and the outlet of the low-grade thermal energy storage subsystem 1 may be connected via a pipeline; The second input port 42 and the outlet of the heat-using subsystem 3 may be connected via a pipeline; The outlet of the gas tank 4 can be connected to the heat storage subsystem 2 through a pipeline; The gas tank 4 is a sealed container with good mechanical strength and can withstand high temperatures; An agitator or flow channel may also be provided inside the gas tank 4 to promote sufficient mixing of the first heat carrier and the third heat carrier; After mixing, the temperature of the first heat carrier and the third heat carrier is 50°C to 150°C.

[0051] In specific implementation, the low-grade thermal energy storage subsystem 1 transports the first heat carrier along the first input port 41 to the gas tank 4, and the heat subsystem 3 transports the third heat carrier along the second input port 42 to the gas tank 4. After the first heat carrier contacts the third heat carrier, the heat carrier with a higher temperature releases heat, while the heat carrier with a lower temperature absorbs heat. Eventually, the temperatures of the first heat carrier and the third heat carrier reach equilibrium, and then the first heat carrier and the third heat carrier are transported to the heat storage subsystem 2 for heating.

[0052] In the present invention, the gas tank 4 mixes the first heat carrier from the low-grade thermal energy storage subsystem 1 and the third heat carrier from the heat-using subsystem 3 to make the temperature distribution of the two heat carriers more uniform. After the first heat carrier and the third heat carrier are transported to the heat storage subsystem 2, the temperature gradient can be reduced, which is conducive to rapid heating and improving the heating efficiency of the heat storage subsystem 2, thereby improving the overall thermal efficiency of the system.

[0053] During specific implementation, a control system may also be provided in the present invention; The control system can be connected to the gas tank 4 and is used to dynamically adjust the mixing ratio and output flow of the first heat carrier and the third heat carrier according to real-time monitoring of the temperature and flow of the first heat carrier and the third heat carrier in the gas tank 4 to ensure that the temperature distribution of the mixed first heat carrier and the third heat carrier is uniform.

[0054] In some embodiments, see Figure 3 , the gas tank 4 is provided with a heat-insulating layer.

[0055] It should be noted that the insulation layer can be made of materials with low thermal conductivity, such as ceramic fiber, glass wool or polyurethane foam, etc. The thickness of the insulation layer can be between 5 cm and 10 cm; The insulation layer can be installed by pasting, winding or modular installation. It is necessary to ensure that the insulation layer is tightly fitted to the surface of the gas tank 4 and use sealing materials to prevent heat loss.

[0056] In the present invention, the provision of an insulation layer effectively reduces heat exchange between the first and third heat carriers within gas tank 4 and the external environment, minimizing heat loss during storage and mixing. This reduced heat loss allows the two mixed heat carriers to enter the heat storage subsystem 2 at a higher temperature, improving the heating efficiency of the heat storage particles and more efficiently converting low-grade heat into high-temperature energy.

[0057] In some embodiments, see Figure 4 , the system further includes a fan 5, the air inlet end of the fan 5 is connected to the outlet of the heat subsystem 3, and the air outlet end of the fan 5 is connected to the second input port 42 of the gas tank 4; The fan 5 is configured to blow the third heat carrier into the gas tank 4 .

[0058] It should be noted that the fan 5 can be a centrifugal fan 5 or an axial flow fan 5, etc. The fan 5 can maintain a certain pressure and even air supply, and can withstand a certain temperature; The air inlet of the fan 5 and the outlet of the heat-using subsystem 3 can be connected by a pipeline; The air outlet of the fan 5 and the second input port 42 of the gas tank 4 may be connected via a pipeline; In specific implementation, the third heat carrier discharged from the heat subsystem 3 is blown by the fan 5, discharged from the air outlet, and then enters the gas tank 4 along the second input port 42 to mix with the first heat carrier.

[0059] In the present invention, fan 5 is provided to quickly and efficiently transport the third heat carrier into gas tank 4 through forced convection, thereby increasing the flow rate and mixing efficiency of the third heat carrier and effectively reducing heat loss during the transport process. Forced transport by fan 5 allows the third heat carrier to mix more evenly with the first heat carrier.

[0060] In some embodiments, see Figure 5 , the low-grade thermal energy storage subsystem 1 is provided with a heat pump 6; The heat pump 6 is configured to heat the first heat carrier in the low-grade thermal energy storage subsystem 1 with a temperature less than 50°C.

[0061] It should be noted that the heat pump 6 can be an air source heat pump 6 or a ground source heat pump 6 and the like.

[0062] In specific implementation, the heat pump 6 is first started to heat the first heat carrier with a temperature of less than 50°C in the low-grade thermal energy storage subsystem 1 to 50°C~150°C; and then the first heat carrier is transported to the energy storage subsystem for heating treatment.

[0063] In the present invention, heat pump 6 is provided to elevate low-grade thermal energy below 50°C to a higher temperature, thereby improving its utilization efficiency. Heat pump 6 is particularly suitable for recycling low-grade heat sources such as low-temperature waste heat, low-temperature geothermal energy, and seawater heat. The heating effect of heat pump 6 raises the temperature of the first heat carrier, making it more suitable for further heating in heat storage subsystem 2, thereby increasing the heating efficiency of the heat storage particles and thus improving the overall thermal efficiency of the system.

[0064] In order to enable those skilled in the art to more clearly understand the present invention, the heat energy recovery and utilization system based on low-grade heat energy described in the present invention is now described in detail through the following embodiments.

[0065] Example 1 use Figure 5 The heat energy recovery and utilization system based on low-grade thermal energy is shown.

[0066] (1) The flue gas with a temperature lower than 150°C in the low-grade thermal energy storage subsystem 1 (the flue gas comes from industrial low-temperature waste heat) is transported to the gas tank 4 along the first input port 41. If there is flue gas with a temperature lower than 50°C in the low-grade thermal energy storage subsystem 1, the heat pump 6 is first started to heat the flue gas to 50°C~150°C, and then the flue gas is transported to the gas tank 4 along the first input port 41; (2) After the first heat carrier (flue gas) in the gas tank 4 is discharged from the outlet, it enters the heat storage device 21. Solar energy is used to power the resistance heating device 22 (which is a resistance heater). The resistance heater heats the heat storage particles (aluminum oxide particles with a particle size of 1.5 cm) in the heat storage device 21 to 2000 °C. After the first heat carrier enters the heat storage device 21, the heat storage particles heat the first heat carrier. After the first heat carrier absorbs heat, a second heat carrier is obtained. The temperature of the second heat carrier is 1500 °C. (3) The second heat carrier at 1500 °C is discharged from the outlet and enters the heat-using subsystem 3 to provide heat for the heat-using subsystem 3. The second heat carrier is cooled to below 50 °C to obtain the third heat carrier; (3) The third heat carrier is discharged along the outlet, enters the fan 5 through the air inlet of the fan 5, and blows the third heat carrier out along the air outlet. Then, the third heat carrier enters the gas tank 4 through the second input port 42, and is mixed with the flue gas output by the low-grade thermal energy storage subsystem 1. The mixture is then transported to the heat storage device 21. The heat storage particles heat the first heat carrier and the third heat carrier to obtain a second heat carrier with a temperature of 1000°C to 1500°C. (4) The second heat carrier is transported to the heat-using subsystem 3 to provide heat, and a third heat carrier with a temperature lower than 50°C is obtained. Step (3) is repeated to form a cycle in the system, so that the flue gas can be recycled and the low-grade heat energy is converted into high-temperature heat energy to continue to provide heat for the heat-using subsystem 3; The low-grade thermal energy in Example 1 can also be derived from low-temperature geothermal energy and seawater heat. The first heat carrier can also be air, nitrogen, carbon dioxide, or water vapor. The resistance heater can be replaced with an electromagnetic induction heater, and the power source can be replaced with wind energy.

[0067] In summary, the present invention provides a heat recovery and utilization system based on low-grade thermal energy. Using the heat storage particles in the heat storage subsystem, the first heat carrier is heated from below 150°C to 1000°C–1500°C, significantly improving the quality of the heat energy. This enables direct use in high-quality thermal energy demand scenarios such as industrial production or building heating, significantly enhancing the utilization value and economic efficiency of low-grade thermal energy. Furthermore, compared to traditional sensible heat storage materials, the present invention improves the overall efficiency of heat recovery through the efficient heating of the heat storage particles.

[0068] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0069] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0070] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements that are inherent to such process, method, article, or terminal device. In the absence of further restrictions, an element defined by the phrase "comprises a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0071] The above is a detailed introduction to a heat recovery and utilization system based on low-grade thermal energy provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for general technical personnel in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A heat recovery and utilization system based on low-grade heat energy, characterized in that: The system comprises a low-grade thermal energy storage subsystem (1), a heat storage subsystem (2) and a heat utilization subsystem (3) connected in sequence; The outlet of the low-grade thermal energy storage subsystem (1) is connected to the inlet of the heat storage subsystem (2), and the low-grade thermal energy storage subsystem (1) is configured to store a first heat carrier and transport the first heat carrier to the heat storage subsystem (2); The outlet of the heat storage subsystem (2) is connected to the inlet of the heat-using subsystem (3); the heat storage subsystem stores heat storage particles; the heat storage subsystem (2) is configured to heat the first heat carrier with the heat storage particles to absorb heat to form a second heat carrier, and to transport the second heat carrier to the heat-using subsystem (3); The heat-using subsystem (3) is configured to consume the heat of the second heat carrier, cool the heat carrier, and form a third heat carrier; Wherein, the temperature of the second heat carrier is 1000 ℃~1500 ℃; The first heat carrier is one of air, nitrogen, carbon dioxide, flue gas and water vapor carrying low-grade thermal energy, and the temperature of the first heat carrier is not higher than 150°C.

2. The heat energy recovery and utilization system based on low-grade heat energy according to claim 1, characterized in that: The outlet of the heat-using subsystem (3) is connected to the inlet of the heat-storage subsystem (2); The heat-using subsystem (3) is further configured to transport the third heat carrier to the heat storage subsystem (2) for heating.

3. The heat energy recovery and utilization system based on low-grade heat energy according to claim 1, characterized in that: The low-grade thermal energy is one of industrial low-temperature waste heat, low-temperature geothermal heat and seawater heat.

4. The heat energy recovery and utilization system based on low-grade heat energy according to claim 1, characterized in that: The heat storage subsystem (2) includes a heat storage device (21) and a heating device (22); The inlet of the heat storage device (21) is connected to the outlet of the low-grade thermal energy storage subsystem (1), and the outlet of the heat storage device (21) is connected to the inlet of the heat-using subsystem (3). The heat storage device (21) is configured to store the heat storage particles and transport the second heat carrier to the heat-using subsystem (3); The heating device (22) is connected to the heat storage device (21), and the heating device (22) is used to heat the heat storage particles.

5. The heat energy recovery and utilization system based on low-grade heat energy according to claim 4 is characterized in that: The particle size of the heat storage particles is less than 2 cm and the melting point is greater than 2000°C.

6. The heat energy recovery and utilization system based on low-grade heat energy according to claim 4, characterized in that: The heating device (22) is a resistance heater or an electromagnetic induction heater; The heating device (22) is powered by wind energy or solar energy.

7. The heat energy recovery and utilization system based on low-grade heat energy according to claim 1, characterized in that: The system further comprises a gas tank (4); The gas tank (4) comprises a first input port (41) and a second input port (42); The first input port (41) is connected to the outlet of the low-grade thermal energy storage subsystem (1), the second input port (42) is connected to the outlet of the heat-using subsystem (3), and the outlet of the gas tank (4) is connected to the heat storage subsystem (2); The gas tank (4) is configured to mix the first heat carrier and the third heat carrier, and then transport them to the heat storage subsystem (2).

8. The heat energy recovery and utilization system based on low-grade heat energy according to claim 7, characterized in that: The gas tank (4) is provided with a heat-insulating layer.

9. The heat energy recovery and utilization system based on low-grade heat energy according to claim 7, characterized in that: The system further comprises a fan (5), an air inlet end of the fan (5) being connected to the outlet of the heat-using subsystem (3), and an air outlet end of the fan (5) being connected to the second input port (42) of the gas tank (4); The fan (5) is configured to blow the third heat carrier into the gas tank (4).

10. The heat energy recovery and utilization system based on low-grade heat energy according to claim 1, characterized in that: The low-grade thermal energy storage subsystem (1) is provided with a heat pump (6); The heat pump (6) is configured to heat a first heat carrier in the low-grade thermal energy storage subsystem (1) with a temperature less than 50°C.

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