A compressed air energy storage waste heat recovery system based on heat pump coupling and a method for operating the same

Abstract

The application discloses a compressed air energy storage waste heat recovery system based on heat pump coupling and an operation method thereof, and belongs to the technical field of energy storage and heat supply. The system comprises a compressor, an inter-stage heat exchanger, a generator, a high-temperature heat pump unit, a high-temperature heat storage tank, a low-temperature heat storage tank, a gas storage, an inter-stage heater, an expander and a heat supply interface. The outlet of the compressor is connected with the gas storage through the inter-stage heat exchanger, the gas storage is connected with the expander and the generator through the inter-stage heater, the inter-stage heat exchanger and the evaporation side of the high-temperature heat pump unit form a first closed loop, the condensation side of the high-temperature heat pump unit is connected with the inter-stage heater and the heat supply interface through the high-temperature heat storage tank respectively, and the inter-stage heater is connected with the condensation side of the high-temperature heat pump unit through the low-temperature heat storage tank to form a second closed loop. The application realizes efficient recovery and grade improvement of compression heat through heat pump coupling, and enhances the comprehensive energy utilization efficiency of the energy storage system and the regional heat supply capacity.

Description

Technical Field

[0001] This invention relates to the field of energy storage and heating technology, specifically to a compressed air energy storage waste heat recovery system based on heat pump coupling and its operation method. Background Technology

[0002] Compressed air energy storage technology, as a large-scale, long-term energy storage method, plays an important role in power peak shaving and renewable energy consumption. In traditional compressed air energy storage systems, in order to improve system efficiency, heat exchangers are usually used to recover the heat generated during the compression stage, and this heat is used to heat the air entering the expander during the energy release stage.

[0003] However, in multi-stage compression processes, the interstage exhaust temperature is typically in the medium-to-low temperature range due to the compression ratios of each stage. This low-to-medium grade compression heat has a low energy density when directly stored or reused, making it difficult to drive efficient expansion. Simultaneously, due to the low temperature, a significant proportion of heat is lost during transmission and long-term storage, and it cannot be directly connected to industrial steam or high-quality heating networks, resulting in substantial waste heat. Furthermore, during the energy release stage, if heating relies solely on low-grade waste heat, the expander inlet temperature remains low, limiting the system's electro-electric conversion efficiency.

[0004] Therefore, how to efficiently recover and improve the grade of low-grade waste heat in compressed air energy storage systems, and achieve efficient storage and flexible utilization of thermal energy, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a compressed air energy storage waste heat recovery system based on heat pump coupling and its operation method, so as to overcome the problem that low-grade compression heat is difficult to utilize efficiently in existing compressed air energy storage systems.

[0006] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a compressed air energy storage waste heat recovery system based on heat pump coupling, including a compressor, an interstage heat exchanger, a generator, a high-temperature heat pump unit, a high-temperature heat storage tank, a low-temperature heat storage tank, an air storage tank, an interstage heater, an expander, and a heating interface. The compressor outlet is connected to the air storage tank inlet via the hot fluid side of the interstage heat exchanger. The air storage tank outlet is connected to the expander inlet via the cold fluid side of the interstage heater. The expander output is connected to the generator. The cold fluid side outlet of the interstage heat exchanger is connected to the evaporator side inlet of the high-temperature heat pump unit. The evaporator side outlet of the high-temperature heat pump unit is connected to the cold fluid side inlet of the interstage heat exchanger, forming a first closed loop. The condenser side outlet of the high-temperature heat pump unit is connected to the inlet of the high-temperature heat storage tank. The outlet of the high-temperature heat storage tank is divided into two paths: the first path connects to the hot fluid side inlet of the interstage heater, and the second path connects to the heating interface. The hot fluid side outlet of the interstage heater connects to the inlet of the low-temperature heat storage tank. The low-temperature heat storage tank outlet connects to the condenser side inlet of the high-temperature heat pump unit, forming a second closed loop.

[0007] A further improvement of the present invention is that it also includes a circulating pump, which is installed on the pipeline between the evaporator-side outlet of the high-temperature heat pump unit and the cold fluid-side inlet of the interstage heat exchanger; the first closed loop is driven by the circulating pump to operate the intermediate heat transfer medium, the interstage heat exchanger is used to transfer the heat of the compressed gas generated by the compressor to the intermediate heat transfer medium, and the evaporator side of the high-temperature heat pump unit is used to absorb the heat of the intermediate heat transfer medium to cause the heat pump working fluid to undergo a phase change.

[0008] A further improvement of the present invention is that the evaporator side of the high-temperature heat pump unit is physically coupled to the interstage heat exchanger. The physical coupling includes integration within the same housing or connection via a pre-set length of insulated pipe, which is used to reduce heat loss during the transmission of the intermediate heat transfer medium.

[0009] A further improvement of the present invention is that a non-azeotropic working fluid is used inside the high-temperature heat pump unit; the non-azeotropic working fluid is used to reduce irreversible losses in the heat exchange process between the evaporator and condenser sides of the high-temperature heat pump unit by utilizing the glide temperature characteristics.

[0010] A further improvement of the present invention is that a one-way valve is provided between the hot fluid side of the interstage heat exchanger and the inlet of the gas storage tank. The one-way valve is used to prevent the gas in the gas storage tank from flowing back to the interstage heat exchanger.

[0011] A further improvement of the present invention is that it also includes a first control valve and a second control valve. The first control valve is disposed on a first path and is used to regulate the flow rate of the heat medium to the interstage heater. The second control valve is disposed on a second path and is used to regulate the flow rate of the heat medium to the heating interface.

[0012] A further improvement of the present invention is that the heat transfer fluid at the hot fluid side outlet of the interstage heater flows into the low-temperature heat storage tank after heat exchange and cooling; the low-temperature heat storage tank is used to temporarily store the cooled heat transfer fluid and input the cooled heat transfer fluid as the return water reference on the condenser side of the high-temperature heat pump unit into the condenser side inlet of the high-temperature heat pump unit; the interstage heater is used to heat the compressed gas from the gas storage tank in stages; the heat source for stage heating is taken from the heat transfer fluid output from the high-temperature heat storage tank; the interstage heater is used to restore the compressed gas to a preset high temperature state before entering the next stage expander.

[0013] The operation method of the compressed air energy storage waste heat recovery system based on heat pump coupling, as described above, includes the following steps: compressing gas and transferring the heat of compression to the evaporator side of the high-temperature heat pump unit through an interstage heat exchanger, causing the heat pump working fluid to absorb heat and undergo a phase change; the high-temperature heat pump unit compresses and upgrades the phase-change heat pump working fluid, and releases the upgraded heat to the heat transfer fluid from the low-temperature heat storage tank on the condenser side of the high-temperature heat pump unit, causing the heat transfer fluid to heat up and be stored in the high-temperature heat storage tank; during the energy release stage, the heat transfer fluid in the high-temperature heat storage tank is diverted to the interstage heater and the heating interface to heat the expanding gas and provide external heat; the heat transfer fluid cooled by heat exchange in the interstage heater flows back to the low-temperature heat storage tank as the return water reference on the condenser side of the high-temperature heat pump unit.

[0014] A further improvement of the present invention is that, during the process of diverting the heat medium fluid in the high-temperature heat storage tank to the interstage heater and the heating interface, the required reheat is calculated according to the output requirements of the expander, and the ratio of the heat medium flow rate to the interstage heater and the flow rate to the heating interface is dynamically adjusted.

[0015] A further improvement of the present invention is that, during the process of compressing gas and transferring the heat of compression to the evaporator side of the high-temperature heat pump unit through the interstage heat exchanger, the flow rate of the heat pump working fluid is adjusted according to the temperature difference data of the gas at the inlet and outlet of the interstage heat exchanger, so as to control the outlet temperature of the compressed gas after each stage of compression within a preset temperature range.

[0016] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The present invention provides an operation method for a compressed air energy storage waste heat recovery system based on heat pump coupling. By constructing a topology structure including a first closed loop and a second closed loop, a high-temperature heat pump unit is used to achieve efficient extraction and quality improvement of compression heat. The improved high-temperature heat energy is stored in a high-temperature heat storage tank, providing a high-quality heat source for subsequent energy release power generation and external heating. By coupling the high-temperature heat pump unit, the low-grade compression heat generated by the compressor is improved into high-temperature heat energy and stored in the high-temperature heat storage tank. During the energy release stage, this high-temperature heat energy is used to perform multi-stage reheating of the gas entering the expander, increasing the inlet temperature of the expander, thereby increasing the gas's work capacity and improving the system's electro-electric conversion efficiency. At the same time, the excess heat in the high-temperature heat storage tank can be output externally through the heating interface, meeting the demand for high-quality industrial-grade heat sources and realizing flexible decoupling and coordinated supply of the two energy carriers, electricity and heat.

[0017] Furthermore, by driving the intermediate heat transfer medium to circulate in the first closed loop through a circulating pump, a stable and efficient transfer of heat from the compressed gas to the heat pump working fluid is achieved.

[0018] Furthermore, by matching the properties of the working fluid with the heat exchange process, the heat exchange temperature difference is reduced, thereby reducing irreversible losses in the heat pump cycle and improving the heating performance coefficient of the heat pump.

[0019] Furthermore, by setting up a one-way valve, it is ensured that compressed gas can only flow from the compression side to the gas storage tank, preventing backflow of high-pressure gas under abnormal operating conditions such as compressor unit shutdown, and ensuring the safe operation of the system.

[0020] Furthermore, through the coordinated action of the first and second control valves, flexible and dynamic allocation of high-temperature heat transfer fluid between power generation and external heat supply is achieved.

[0021] Furthermore, by temporarily storing and reusing the cooled heat transfer fluid through a low-temperature heat storage tank, a complete heat transfer fluid circulation loop is formed, which ensures the stability of the expander inlet air temperature and improves the expansion work capacity.

[0022] The operation method of the compressed air energy storage waste heat recovery system based on heat pump coupling provided by the present invention achieves efficient recovery and flexible scheduling of waste heat of compressed air energy storage system by improving the heat quality and storing it in the energy storage stage and diverting and utilizing the heat in the energy release stage.

[0023] Furthermore, by dynamically adjusting the flow ratio, decoupled control of power generation and heating load is achieved, improving the system's responsiveness to grid peak shaving and heat user demand.

[0024] Furthermore, by precisely controlling the outlet temperature of the compressed gas, the multi-stage compression process is made closer to isothermal compression, thereby reducing the overall power consumption of the compression stage. Attached Figure Description

[0025] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a block diagram of a compressed air energy storage waste heat recovery system based on heat pump coupling according to the present invention.

[0027] Among them, 1. Compressor; 2. Interstage heat exchanger; 3. High-temperature heat pump unit; 4. High-temperature heat storage tank; 5. Low-temperature heat storage tank; 6. Gas storage tank; 7. Expander; 8. Generator; 9. Heating interface; 10. Circulating pump; 11. Interstage heater; 12. First control valve; 13. Second control valve; 14. Check valve. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present 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 present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0032] Furthermore, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This is an explanation of the present invention and not a limitation thereof.

[0034] This invention provides a compressed air energy storage waste heat recovery system based on heat pump coupling, including a compressor 1, an interstage heat exchanger 2, a generator 8, a high-temperature heat pump unit 3, a high-temperature heat storage tank 4, a low-temperature heat storage tank 5, an air storage tank 6, an interstage heater 11, an expander 7, and a heating interface 9; wherein, the outlet of the compressor 1 is connected to the inlet of the air storage tank 6 via the hot fluid side of the interstage heat exchanger 2, the outlet of the air storage tank 6 is connected to the inlet of the expander 7 via the cold fluid side of the interstage heater 11, the output end of the expander 7 is connected to the generator 8, and the outlet of the cold fluid side of the interstage heat exchanger 2 is connected to... The evaporator-side inlet of the high-temperature heat pump unit 3 is connected to the cold fluid-side inlet of the interstage heat exchanger 2, forming a first closed loop. The condenser-side outlet of the high-temperature heat pump unit 3 is connected to the inlet of the high-temperature heat storage tank 4. The outlet of the high-temperature heat storage tank 4 is divided into two paths: the first path is connected to the hot fluid-side inlet of the interstage heater 11, and the second path is connected to the heating interface 9. The hot fluid-side outlet of the interstage heater 11 is connected to the inlet of the low-temperature heat storage tank 5, and the outlet of the low-temperature heat storage tank 5 is connected to the condenser-side inlet of the high-temperature heat pump unit 3, forming a second closed loop.

[0035] The compressor 1, interstage heat exchanger 2, air storage tank 6, interstage heater 11, expander 7, and generator 8 constitute the main path for the system's energy storage and release. During energy storage, the compressor 1 consumes electrical energy to compress atmospheric air to a high-pressure state; the heat generated during compression is extracted by the interstage heat exchanger 2. The cooled high-pressure air is then sent to the air storage tank 6 for storage via the hot fluid side outlet of the interstage heat exchanger 2. During energy release, the air storage tank 6 releases the high-pressure air, which is then heated by the cold fluid side of the interstage heater 11 before entering the expander 7 to perform work, driving the generator 8 to output electrical energy. The core function of the first closed loop is to realize the extraction and transfer of compression heat. The cold fluid side of the interstage heat exchanger 2, the evaporator side of the high-temperature heat pump unit 3, and the pipelines connecting them together form a closed loop. In this loop, the intermediate heat transfer medium absorbs the heat released by the compressed gas in the interstage heat exchanger 2, carries the heat into the evaporator side of the high-temperature heat pump unit 3, transfers the heat to the heat pump working fluid and then the temperature decreases, and then returns to the interstage heat exchanger 2 to continue absorbing the heat of compression, and so on.

[0036] The condenser-side outlet of the high-temperature heat pump unit 3 is connected to the inlet of the high-temperature heat storage tank 4. The outlet of the high-temperature heat storage tank 4 is divided into two paths. The first path is connected to the hot fluid side inlet of the interstage heater 11, and the second path is connected to the heating interface 9. The hot fluid side outlet of the interstage heater 11 is connected to the inlet of the low-temperature heat storage tank 5, and the outlet of the low-temperature heat storage tank 5 is connected to the condenser-side inlet of the high-temperature heat pump unit 3, forming a second closed loop.

[0037] The core function of the second closed loop is to realize the storage, distribution, and return water circulation of the upgraded heat energy. The high-temperature heat pump unit 3 upgrades the low-grade compression heat absorbed from the first closed loop and releases the high-temperature heat to the flowing heat medium on its condenser side. The heated heat medium enters the high-temperature heat storage tank 4 for storage. As the storage center of high-quality heat energy, the high-temperature heat storage tank 4 has two outlets: one leads to the interstage heater 11, which is used to heat the high-pressure air before entering the expander 7 during the energy release stage, thereby increasing the initial temperature of the expander 7 inlet and increasing the gas's work capacity; the other leads to the heating interface 9, which is used to output the excess high-temperature heat to meet the external heat load demand such as industrial steam or district heating. After being cooled by heat exchange in the interstage heater 11, the heat medium flows into the low-temperature heat storage tank 5 for temporary storage and serves as the return water reference on the condenser side of the high-temperature heat pump unit 3. It then re-enters the condenser side of the high-temperature heat pump unit 3 to absorb the upgraded heat, completing the complete heat medium cycle. This dual-tank cascade design allows the high-temperature heat storage tank 4 and the low-temperature heat storage tank 5 to respectively perform the functions of storing high-temperature heat energy and buffering low-temperature return water. This not only maintains the stable circulation of the heat transfer fluid in the second closed loop, but also provides a physical basis for the system to flexibly allocate heat energy according to the grid peak-shaving demand and the user-side heat load curve.

[0038] Through the above topology, this embodiment constructs a comprehensive energy system architecture with functions of electrical energy storage, thermal energy upgrading and storage, and coordinated heating. The first closed loop efficiently extracts the low-grade waste heat generated during compression and transfers it to the heat pump working fluid, while the second closed loop stores, distributes, and recycles the upgraded high-temperature thermal energy. The two closed loops are thermodynamically coupled through the high-temperature heat pump unit 3, which not only solves the problem of inefficient utilization of low-grade compression heat in traditional compressed air energy storage systems, but also realizes flexible decoupling and coordinated supply of the two energy carriers, electricity and heat.

[0039] Specifically, it also includes a circulating pump 10, which is installed on the pipeline between the evaporator-side outlet of the high-temperature heat pump unit 3 and the cold fluid-side inlet of the interstage heat exchanger 2; the first closed loop is driven by the circulating pump 10 to run the intermediate heat transfer medium, the interstage heat exchanger 2 is used to transfer the heat of the compressed gas generated by the compressor 1 to the intermediate heat transfer medium, and the evaporator side of the high-temperature heat pump unit 3 is used to absorb the heat of the intermediate heat transfer medium to cause the heat pump working fluid to undergo a phase change.

[0040] The circulating pump 10, acting as the heart of the first closed loop, provides power for the continuous circulation of the intermediate heat transfer medium between the interstage heat exchanger 2 and the evaporator side of the high-temperature heat pump unit 3. The intermediate heat transfer medium acts as a heat carrier, absorbing the heat of compression released by the compressed gas on the cold fluid side of the interstage heat exchanger 2, thus increasing its own temperature. It is then pressurized and transported by the circulating pump 10 to the evaporator side of the high-temperature heat pump unit 3, where it releases the heat it carries to the heat pump working fluid, causing the working fluid to absorb heat and evaporate, completing the phase change process. The cooled intermediate heat transfer medium then flows out from the evaporator side outlet and re-enters the interstage heat exchanger 2 via the circulating pump 10, beginning a new round of heat absorption circulation.

[0041] Specifically, the evaporator side of the high-temperature heat pump unit 3 is physically coupled to the interstage heat exchanger 2. The physical coupling includes integration within the same housing or connection via a pre-set length of insulated pipe, which is used to reduce heat loss during the transmission of the intermediate heat transfer medium.

[0042] The physical coupling mentioned here refers to the close physical connection between the evaporator side of the high-temperature heat pump unit 3 and the interstage heat exchanger 2 in space, so as to minimize the transmission path of the intermediate heat transfer medium from the heat absorption end to the heat release end. As a specific implementation, the evaporator side of the high-temperature heat pump unit 3 can be directly integrated into the shell of the interstage heat exchanger 2. For example, an independent evaporation chamber can be defined inside the shell of the interstage heat exchanger 2, and the evaporator tube bundle or plate evaporator elements of the heat pump can be directly arranged in this chamber to exchange heat with the flowing intermediate heat transfer medium. After absorbing the heat from the compressed gas in the interstage heat exchanger 2, the intermediate heat transfer medium transfers heat directly to the heat pump working fluid within the same shell with almost no external piping. The transmission path is compressed to the extreme, and heat loss is almost negligible. This not only reduces heat loss but also saves equipment footprint and piping installation costs, making the system more compact.

[0043] As an alternative implementation, when an integrated structure cannot be used due to limitations in equipment manufacturing processes or on-site installation conditions, the evaporator side of the high-temperature heat pump unit 3 can be tightly connected to the interstage heat exchanger 2 via insulated pipes of a preset length. The preset length refers to the maximum pipe length calculated based on the system's allowable heat loss threshold; for example, in a 10MW system, this length is typically controlled to within 1 meter, or even shorter. Simultaneously, the pipes are externally covered with high-performance insulation materials, such as aerogel felt, vacuum insulation panels, or polyurethane foam, to further suppress heat dissipation. Through this short-distance insulated pipe connection, the intermediate heat transfer medium can rapidly enter the heat pump evaporator side with an extremely low temperature drop after leaving the interstage heat exchanger 2, effectively transferring the majority of the heat to the heat pump working fluid.

[0044] In this embodiment, the intermediate heat transfer medium is forced to circulate in the first closed loop by a circulating pump 10. Combined with the physical coupling design between the evaporator side and the interstage heat exchanger 2, efficient heat transfer of compression is ensured from both the driving source and the transmission path. The circulating pump 10 provides a stable driving force, avoiding lag in heat transfer; the physical coupling shortens the heat transfer distance from a spatial structure perspective, suppressing ineffective heat dissipation during transmission. The synergistic effect of these two factors allows the low-grade heat of compression generated by the compressor 1 to be transported to the high-temperature heat pump unit 3 with extremely high efficiency, laying a solid foundation for subsequent heat quality improvement.

[0045] Specifically, the high-temperature heat pump unit 3 uses a non-azeotropic working fluid inside; the non-azeotropic working fluid is used to reduce irreversible losses in the heat exchange process between the evaporator and condenser sides of the high-temperature heat pump unit 3 by utilizing the glide temperature characteristics.

[0046] A non-azeotropic working fluid refers to a working fluid composed of two or more pure working fluids with different boiling points mixed in a certain proportion. During the isobaric phase change process, the gas and liquid phases have different compositions, therefore the phase change temperature is not a constant value but changes continuously within a temperature range as the phase change process progresses; this temperature range is called the glide temperature. In contrast, pure working fluids or azeotropic working fluids maintain a constant temperature during isobaric phase changes. This embodiment utilizes this unique glide temperature characteristic of the non-azeotropic working fluid to match the temperature changes of the heat exchange fluids on the evaporator and condenser sides of the high-temperature heat pump unit 3, thereby fundamentally reducing irreversible losses during the heat exchange process.

[0047] In the first closed loop, the intermediate heat transfer medium absorbs heat from the compressed gas in the interstage heat exchanger 2, and its temperature rises. It then enters the evaporator side of the high-temperature heat pump unit 3, transferring heat to the heat pump working fluid while its own temperature gradually decreases. This is a typical variable-temperature heat release process. If a pure working fluid is used, its temperature remains constant during constant-pressure evaporation on the evaporator side. This results in a large average heat transfer temperature difference between the intermediate heat transfer medium and the heat pump working fluid. According to the second law of thermodynamics, the larger the heat transfer temperature difference, the greater the irreversible loss during heat transfer. This loss directly manifests as a decrease in the coefficient of performance (COP) of the heat pump unit. However, by using a non-azeotropic mixed working fluid, the working fluid absorbs heat and evaporates on the evaporator side, and its temperature gradually increases along the glide temperature curve from a lower temperature. This temperature change trend precisely matches the cooling trend of the intermediate heat transfer medium, significantly reducing the average heat transfer temperature difference between the two temperature curves and thus greatly reducing the irreversible loss during the evaporator side heat transfer process.

[0048] The same mechanism applies to the condenser side. In the second closed loop, the heat transfer fluid from the low-temperature heat storage tank 5 enters the condenser side of the high-temperature heat pump unit 3 to absorb heat, and its temperature gradually increases. This is a variable-temperature heat absorption process. When the non-azeotropic working fluid condenses at constant pressure on the condenser side, its temperature gradually decreases from a higher temperature along the glide temperature curve, forming a good temperature match with the heating trend of the heat transfer fluid. This reduces the average heat transfer temperature difference on the condenser side and decreases the irreversible losses in the heat transfer process on this side.

[0049] By employing a non-azeotropic mixed working fluid, the temperature curves between the heat pump working fluid and the heat exchange fluid are well matched by utilizing its glide temperature characteristics. This reduces irreversible losses in the heat exchange process on the evaporation and condensation sides from a microscopic thermodynamic perspective, significantly improving the heating COP of the high-temperature heat pump unit 3 and providing key working fluid property support for the efficient operation of the entire compressed air energy storage waste heat recovery system.

[0050] Specifically, a one-way valve 14 is provided between the hot fluid side of the interstage heat exchanger 2 and the inlet of the gas storage tank 6. The one-way valve 14 is used to prevent the gas in the gas storage tank 6 from flowing back to the interstage heat exchanger 2.

[0051] A one-way valve 14 is a mechanical valve that allows fluid to flow in only one direction and automatically closes under reverse pressure differential. Its installation direction is consistent with the normal flow direction of the compressed gas, allowing gas to flow from the interstage heat exchanger 2 to the gas storage tank 6, while prohibiting gas from flowing back from the gas storage tank 6 to the interstage heat exchanger 2. The one-way valve 14 can be a spring-loaded type. The spring-loaded one-way valve 14 has a valve disc and a preload spring inside. Under normal operating conditions, the pressure of the compressed gas flowing out of the interstage heat exchanger 2 is sufficient to overcome the preload force of the spring, pushing the valve disc open, and the gas smoothly passes through the one-way valve 14 into the gas storage tank 6. When the compressor 1 unexpectedly stops operating due to power outage, equipment failure, or planned shutdown, the compressed gas is no longer continuously supplied from the compressor 1 side, and the pressure at the hot fluid side outlet of the interstage heat exchanger 2 drops rapidly. At this time, the high-pressure gas stored in the gas storage tank 6, under the action of reverse pressure differential, will attempt to backflow along the pipeline towards the interstage heat exchanger 2 and the compressor 1. This reverse airflow acts on the back of the valve disc of the one-way valve 14, and together with the preload of the spring, pushes the valve disc quickly against the valve seat, achieving automatic valve closure. Because the preload of the spring is always present, even in the initial stage when the reverse pressure difference is small, the valve disc can fit tightly against the valve seat, ensuring reliable sealing.

[0052] By installing a one-way valve 14 between the interstage heat exchanger 2 and the air storage tank 6, an automatic and instantaneous blockage of the reverse airflow is achieved using a purely mechanical structure, without any electrical control signals or manual intervention, fundamentally eliminating the aforementioned safety hazards. This passive safety protection mechanism's reliability does not depend on the integrity of the control system or power supply. Even under the worst-case scenario of a complete system power outage, it can still effectively provide protection, ensuring the inherent safety of the compressed air energy storage system over a decades-long operating cycle.

[0053] Specifically, it also includes a first control valve 12 and a second control valve 13. The first control valve 12 is located on the first path and is used to regulate the flow of heat medium to the interstage heater 11. The second control valve 13 is located on the second path and is used to regulate the flow of heat medium to the heating interface 9.

[0054] The two control valves work together to determine the distribution ratio of the high-temperature heat transfer fluid output from the high-temperature heat storage tank 4 between power generation and external heat supply. As a specific implementation, both the first control valve 12 and the second control valve 13 can be electrically controlled regulating valves, with their opening continuously adjusted by the central controller according to the system operation strategy. The electrically controlled regulating valve contains an actuator and a valve core assembly. The actuator receives analog signals or digital communication commands from the controller, driving the valve core to move linearly or rotary within the valve body, thereby changing the flow area of ​​the valve orifice and achieving precise control of the heat transfer fluid flow rate. It should be understood that the type of control valve is not limited to an electrically controlled regulating valve; in other embodiments, pneumatic or hydraulic regulating valves can also be used, as long as continuous or graded flow rate adjustment can be achieved according to the control signal.

[0055] During the energy release phase, the central controller calculates the optimal allocation ratio of the two heat medium flow rates in real time based on the output requirements of generator 8 and the external heat load demand. When the grid peak-shaving pressure is high and the power generation output needs to be maximized, the controller increases the opening of the first control valve 12 and correspondingly decreases the opening of the second control valve 13, allowing more high-temperature heat medium fluid to flow to the interstage heater 11. This ensures that the compressed gas entering the expander 7 is fully heated to the preset high-temperature state, thereby obtaining the maximum expansion work capacity. When the external heat load demand increases, the controller increases the opening of the second control valve 13, delivering more high-temperature heat energy to the external heating network through the heating interface 9 to meet the demand for industrial steam or district heating. This flow allocation mechanism, achieved through the coordinated action of two control valves, enables the system to flexibly and dynamically decouple and adjust between power generation and heating, ensuring both the response speed of grid peak shaving and taking into account the heating needs of heat users.

[0056] Specifically, the heat transfer fluid from the hot fluid side outlet of the interstage heater 11 flows into the low-temperature heat storage tank 5 after heat exchange and cooling; the low-temperature heat storage tank 5 is used to temporarily store the cooled heat transfer fluid and input the cooled heat transfer fluid as the return water reference for the condenser side of the high-temperature heat pump unit 3 into the condenser side inlet of the high-temperature heat pump unit 3; the interstage heater 11 is used to heat the compressed gas from the gas storage tank 6 in stages; the heat source for stage heating is taken from the heat transfer fluid output from the high-temperature heat storage tank 4; the interstage heater 11 is used to restore the compressed gas to a preset high temperature state before entering the next stage expander 7.

[0057] During the energy release phase, the high-pressure compressed air released from the gas storage tank 6 needs to be heated by the interstage heater 11 before entering the expander 7. When the system uses a multi-stage expander 7 configuration, the interstage heater 11 is also configured as a multi-stage system, with each interstage heater 11 located between two adjacent expanders 7. The high-temperature heat transfer fluid from the high-temperature heat storage tank 4, after its flow rate is regulated by the first control valve 12, enters the hot fluid side of each interstage heater 11. Inside the interstage heater 11, the high-temperature heat transfer fluid exchanges heat counter-currently with the compressed gas from the gas storage tank 6 or the outlet of the previous expander 7. The compressed gas flows on the cold fluid side, absorbs the heat released by the heat transfer fluid, and its temperature rises significantly, returning to the preset high-temperature state, before entering the next expander 7 to continue performing work. The preset high-temperature state mentioned here refers to the target inlet temperature value determined according to the design operating conditions of the expander 7, which is usually matched with the storage temperature of the high-temperature heat storage tank 4, for example, between 150°C and 180°C. Through this step-by-step heating method, the gas temperature at the inlet of each stage expander 7 can be maintained at a high level, making the entire expansion process closer to isothermal expansion, thereby maximizing the extraction of pressure potential energy from the high-pressure air in the gas storage tank 6 and converting it into output electrical energy of the generator 8.

[0058] After heat exchange is completed in the interstage heater 11, the temperature of the high-temperature heat transfer fluid decreases significantly, from over 150°C upon entry to approximately 60°C to 80°C. This cooled heat transfer fluid is not discarded but is collected through pipelines and transported to the low-temperature heat storage tank 5 for temporary storage. The low-temperature heat storage tank 5, acting as a return water buffer in the second closed loop, can also be equipped with an orifice plate distributor to maintain a temperature gradient and reduce mixing losses between hot and cold fluids. In the next energy storage phase, the cooled heat transfer fluid stored in the low-temperature heat storage tank 5 is drawn out and input as a return water reference to the condenser-side inlet of the high-temperature heat pump unit 3. It then absorbs the heat released by the heat pump working fluid, is heated, and stored in the high-temperature heat storage tank 4, thus completing the full circulation of the heat transfer fluid within the second closed loop. This design, which recovers the heat transfer fluid after heat exchange and uses it as the return water reference, creates a closed loop between the high-temperature heat storage tank 4 and the low-temperature heat storage tank 5. This avoids the waste and frequent replenishment of the heat transfer fluid, maintains a stable working fluid circulation within the second closed loop, and ensures that the return water reference temperature provided by the low-temperature heat storage tank 5 is relatively stable. This is beneficial for the stable control of the heat exchange conditions on the condenser side of the high-temperature heat pump unit 3, thereby ensuring the continuous and efficient operation of the heat pump unit.

[0059] This embodiment achieves flexible and dynamic distribution of high-temperature heat transfer fluid between the interstage heater 11 and the heating interface 9 through the coordinated setting of the first control valve 12 and the second control valve 13. This allows the system to adjust the output ratio of power generation and heating in real time according to the grid peak-shaving demand and the user-side heat load curve. At the same time, the interstage heater 11 heats the compressed gas stage by stage, ensuring that the gas temperature at the inlet of each stage expander 7 is restored to the preset high temperature state, which significantly improves the expansion work capacity. Furthermore, the low-temperature heat storage tank 5 recovers and reuses the heat transfer fluid after heat exchange and cooling, forming a complete closed-loop heat transfer fluid cycle. This achieves efficient cascade utilization of thermal energy at the system level.

[0060] The operation method of the compressed air energy storage waste heat recovery system based on heat pump coupling, as described above, includes the following steps: compressing gas and transferring the compression heat to the evaporation side of the high-temperature heat pump unit 3 through the interstage heat exchanger 2, causing the heat pump working fluid to absorb heat and undergo a phase change; the high-temperature heat pump unit 3 compresses and upgrades the phase-change heat pump working fluid, and releases the upgraded heat to the heat transfer fluid from the low-temperature heat storage tank 5 on the condenser side of the high-temperature heat pump unit 3, so that the heat transfer fluid is heated and stored in the high-temperature heat storage tank 4; during the energy release stage, the heat transfer fluid in the high-temperature heat storage tank 4 is diverted to the interstage heater 11 and the heating interface 9 to heat the expanding gas and provide external heat; the heat transfer fluid cooled by heat exchange in the interstage heater 11 flows back to the low-temperature heat storage tank 5 as the return water reference on the condenser side of the high-temperature heat pump unit 3.

[0061] During periods of low grid load, compressor 1 consumes electrical energy to compress air from atmospheric pressure to high pressure in stages. During each compression stage, the gas temperature rises significantly, generating compression heat with a medium to low temperature grade. Before entering the next stage compressor 1 or gas storage tank 6, this high-temperature compressed gas flows through the hot fluid side of the interstage heat exchanger 2, where it undergoes counter-current heat exchange with the intermediate heat transfer medium on the cold fluid side. After absorbing the heat released by the compressed gas in the interstage heat exchanger 2, the intermediate heat transfer medium carries the heat into the evaporation side of the high-temperature heat pump unit 3. On the evaporation side, the heat pump working fluid absorbs the heat transferred by the intermediate heat transfer medium under low pressure, evaporating from a liquid state to a gaseous state, completing the phase change heat absorption process.

[0062] The gaseous heat pump working fluid, having undergone phase change, enters the compressor 1 of the high-temperature heat pump unit 3, where it is adiabatically compressed to a high-temperature, high-pressure state. Its temperature is raised to a level far exceeding the original heat of compression, for example, from a medium-low temperature of 80°C to 100°C to a high temperature above 150°C. Subsequently, the high-temperature, high-pressure gaseous working fluid enters the condenser side, exchanging heat with the heat transfer fluid from the low-temperature heat storage tank 5. The heat pump working fluid releases latent and sensible heat on the condenser side, condensing from a gaseous state to a liquid state, while the heat transfer fluid absorbs this upgraded high-temperature heat, resulting in a significant temperature increase. The heated heat transfer fluid is then transported to the high-temperature heat storage tank 4 for stratified storage, serving as a reserve of high-quality thermal energy. An orifice plate distributor can be installed inside the high-temperature heat storage tank 4 to maintain a stable temperature gradient, ensuring a clear thermal stratification between the high-temperature and low-temperature heat transfer fluids and reducing mixing losses between the hot and cold fluids within the tank. Through the thermodynamic cycle of a heat pump, low-grade compression heat, which is originally difficult to utilize directly and efficiently, is upgraded into high-grade thermal energy, laying a quality foundation for subsequent energy release for power generation and external heating.

[0063] When the power grid is at its peak load or there is external heat load demand, the system enters the energy release phase. The gas storage tank 6 releases high-pressure compressed air, which needs to be heated before entering the expander 7 to increase its work capacity. At this time, the high-temperature heat transfer fluid stored in the high-temperature heat storage tank 4 is drawn out and split into two paths through pipelines: the first path flows to the interstage heater 11 to heat the high-pressure air about to enter the expander 7, restoring it to a preset high-temperature state, thereby increasing the gas's expansion work capacity; the second path flows to the heating interface 9 to output excess high-temperature heat to meet external heat load demands such as industrial steam and district heating. The specific splitting ratio can be dynamically adjusted according to the power grid's peak-shaving demand and the user-side heat load curve, achieving flexible decoupling and coordinated supply of electricity and heat. For example, during the winter heating season, the flow rate of the heat transfer fluid to the heating interface 9 can be appropriately increased to ensure external heat supply demand; when the power grid's peak-shaving pressure is high, priority is given to ensuring the flow rate of the heat transfer fluid to the interstage heater 11 to maximize power generation output.

[0064] In the interstage heater 11, the high-temperature heat transfer fluid exchanges heat with the high-pressure compressed air from the gas storage tank 6, causing its temperature to decrease, for example, from over 150°C to around 60°C to 80°C. This cooled heat transfer fluid is not directly discharged or cooled, but is transported to the low-temperature heat storage tank 5 for temporary storage. The low-temperature heat storage tank 5 serves as a return water buffer device in the second closed loop, and its outlet is connected to the condenser-side inlet of the high-temperature heat pump unit 3. In the next energy storage stage, the cooled heat transfer fluid in the low-temperature heat storage tank 5 re-enters the condenser side of the high-temperature heat pump unit 3 as a return water reference, absorbing the upgraded heat and completing the complete heat transfer fluid cycle. This dual-tank cascade design allows the heat transfer fluid to form a closed loop between the high-temperature heat storage tank 4 and the low-temperature heat storage tank 5, not only realizing the cascade utilization of thermal energy but also maintaining the stable circulation of the heat transfer fluid within the second closed loop, avoiding waste and frequent replenishment of the heat transfer fluid.

[0065] The operation method of this embodiment realizes the heat quality improvement and storage in the energy storage stage and the heat diversion and utilization in the energy release stage, constructing a complete macroscopic operation process of energy quality improvement, energy release utilization, and water recycling. By using the high-temperature heat pump unit 3 to improve the quality of low-grade compressed heat, the problem of inefficient utilization of compressed heat in traditional compressed air energy storage systems is solved. At the same time, through dual-tank cascading and diversion control, flexible scheduling of high-quality thermal energy is achieved, significantly improving the overall energy utilization efficiency of the system.

[0066] Specifically, during the process of diverting the heat medium fluid in the high-temperature heat storage tank 4 to the interstage heater 11 and the heating interface 9, the required reheat is calculated according to the output requirements of the expander 7, and the ratio of the heat medium flow to the interstage heater 11 and the flow to the heating interface 9 is dynamically adjusted.

[0067] Specifically, during the process of compressing gas and transferring the heat of compression to the evaporator side of the high-temperature heat pump unit 3 through the interstage heat exchanger 2, the flow rate of the heat pump working fluid is adjusted according to the temperature difference data between the inlet and outlet gases of the interstage heat exchanger 2, so as to control the outlet temperature of the compressed gas after each stage of compression within a preset temperature range. In a specific embodiment of the present invention, see... Figure 1 The compressed air energy storage waste heat recovery system based on heat pump coupling includes: a multi-stage compressor unit, an interstage heat exchanger 2, a high-temperature heat pump unit 3, a high-temperature heat storage tank 4, a low-temperature heat storage tank 5, an air storage tank 6, a multi-stage expander, a generator 8, an industrial heating interface 9, a circulating pump 10, an interstage heater 11, a first control valve 12, a second control valve 13, and a check valve 14. The air outlet of the multi-stage compressor unit is connected to the hot fluid inlet of the interstage heat exchanger 2. The hot fluid outlet of the interstage heat exchanger 2 is connected to the inlet of the air storage tank 6 via a one-way valve 14. The cold fluid outlet of the interstage heat exchanger 2 is connected to the evaporator inlet of the high-temperature heat pump unit 3. The evaporator outlet of the high-temperature heat pump unit 3 returns to the cold fluid inlet of the interstage heat exchanger 2 via a circulating pump 10, forming a closed loop. The condenser outlet of the high-temperature heat pump unit 3 is connected to the heat medium inlet of the high-temperature heat storage tank 4. The heat medium outlet of the high-temperature heat storage tank 4 is divided into two paths. The first path is connected to the interstage heater inlet of the multi-stage expander via the first control valve 12. The first circuit is connected to the industrial heating interface 9; the inlet of the low-temperature heat storage tank 5 is connected to the outlet of the interstage heater 11 of the multi-stage expander, and the outlet of the low-temperature heat storage tank 5 is connected to the condenser inlet of the high-temperature heat pump unit 3 to form a heat medium circulation loop; the outlet of the gas storage tank 6 is connected to the air inlet of the multi-stage expander 7 via the interstage heater 11, and the output shaft of the multi-stage expander is mechanically connected to the rotor of the generator 8; the second control valve 13 is installed on the water inlet pipe of the industrial heating interface 9. Through the topological connection of the above components, a comprehensive energy system architecture with electrical energy storage, thermal energy quality improvement and storage and coordinated heating functions is constructed.

[0068] The coupling heat exchange mechanism between the multi-stage compressor unit and the high-temperature heat pump unit 3 is as follows: In energy storage operation mode, the multi-stage compressor unit consumes off-peak electricity from the grid to compress atmospheric air to a high-pressure state. Before entering the next stage, the compressed air produced by each stage of compression must flow through the corresponding interstage heat exchanger 2. The interstage heat exchanger 2 adopts a counter-current heat exchange structure to transfer the medium-low temperature heat (80℃ to 100℃) released by the compressed air to the intermediate heat transfer medium driven by the circulating pump 10. The high-temperature heat pump unit 3 is filled with a high-temperature working fluid. Its evaporator absorbs heat from the interstage heat exchanger 2, causing the working fluid to undergo a phase change from liquid to gas, and then enters the high-temperature heat pump unit 3. The screw compressor performs adiabatic compression, raising the energy grade to a high-temperature vapor state above 150°C. The raised high-temperature working fluid releases heat in the condenser to the heat transfer fluid flowing out of the low-temperature heat storage tank 5, causing the heat transfer fluid to be heated and then input into the high-temperature heat storage tank 4 for stratified storage. This process, through the performance gain effect of the high-temperature heat pump unit 3, achieves deep extraction of waste heat from compressed air. This not only ensures that the inlet temperatures of each stage of the multi-stage compressor unit are within the optimal operating range and reduces compression power consumption, but also reserves a heat source of much higher quality than traditional energy storage systems for subsequent energy release stages and district heating, solving the technical bottleneck of inefficient utilization of low-grade compression heat.

[0069] The cascaded heat storage and heat energy distribution logic of high-temperature heat storage tank 4 and low-temperature heat storage tank 5 is as follows: Both high-temperature heat storage tank 4 and low-temperature heat storage tank 5 are pressure vessels with high-performance insulation layers, and are equipped with orifice plate distributors to maintain a stable temperature gradient. High-temperature heat storage tank 4 monitors its real-time heat reserve status through a logic controller. When the system is in a non-energy release period and the temperature of high-temperature heat storage tank 4 reaches a preset threshold, the logic controller will increase the opening of the second control valve 13 to transfer the excess high-temperature heat energy to the external heating network through the industrial heating interface 9 to replace traditional gas boilers or electric boilers for heating. During the energy release phase, the first control valve 12 is opened first. The high-temperature heat transfer fluid is guided to the heaters of the multi-stage expander to heat the high-pressure air from the gas storage tank 6 in stages. After heat exchange and cooling, the temperature of the heat transfer fluid drops to about 60°C to 80°C, and then flows into the low-temperature heat storage tank 5 for temporary storage, serving as the return water reference for the condenser of the high-temperature heat pump unit 3. This dual-tank cascade design, combined with the coordinated action of the first control valve 12 and the second control valve 13, realizes the dynamic allocation of heat energy according to the peak-shaving demand of the power grid and the heat load curve of the user side, which greatly improves the thermal economy of the system throughout its entire life cycle and can flexibly adjust the "heat-determined by electricity" or "electricity-determined by heat" operation strategy according to seasonal differences.

[0070] The thermal cycle and reheat path of the multi-stage expander are described as follows: High-pressure compressed air released from the gas storage tank 6 first enters the first-stage preheater, where it undergoes sufficient heat exchange with the high-temperature medium from the high-temperature heat storage tank 4, causing its initial expansion temperature to reach the maximum design requirement. After the air has performed work in the first-stage multi-stage expander, both its pressure and temperature decrease simultaneously. To prevent brittle damage to the turbine blades or icing of water vapor in the air due to excessively low temperatures, the air is introduced into the reheater located between stages. The heat source for this reheater is also taken from the high-temperature heat storage tank 4, and the flow rate of the heat medium to each stage of the reheater is precisely adjusted. This ensures that the air returns to a high temperature before entering the next stage of the multi-stage expander; the generator 8, driven by the multi-stage expander, converts the stored pressure potential energy into stable electrical energy output; this multi-stage reheat cycle based on the high-temperature heat pump unit 3 as a heat source makes the air expansion process closer to an isothermal process, theoretically maximizing the recovery of physical energy stored in the gas storage tank 6, and the exhaust gas after expansion still has a certain amount of residual heat, which can be returned to the low-temperature heat storage tank 5 via the tail heat exchanger or directly used to preheat the return water of the industrial heating interface 9, forming a closed-loop cascade utilization system of energy.

[0071] The system's safety protection and working fluid management mechanisms under extreme operating conditions are as follows: The system integrates a safety monitoring matrix, including pressure sensors at the outlet of the multi-stage compressor unit, level and stress sensors in the gas storage tank 6, and pressure relief valves in the high-temperature heat storage tank 4; the working fluid buffer tank is connected in the circulation loop of the high-temperature heat pump unit 3 to absorb pipeline pressure fluctuations caused by thermal expansion and contraction, and to replenish working fluid losses caused by micro-leakage in real time; when the multi-stage compressor unit unexpectedly shuts down, causing the heat source of the interstage heat exchanger 2 to be interrupted, the system will automatically shut down the circulation pump 10 and switch the high-temperature heat pump unit 3 to standby mode, while preventing the storage tank from running out of power through the one-way valve 14. High-pressure air in gas storage tank 6 flows back to the compression side; if the temperature or pressure in high-temperature heat storage tank 4 exceeds the safety limit, the emergency relief circuit will guide the heat transfer fluid into a dedicated emergency cooling fan unit for rapid cooling; in addition, the system controller will calculate the real-time COP value of high-temperature heat pump unit 3 in real time. Once the efficiency is lower than the set benchmark due to working fluid deterioration or heat exchanger scaling, the system will trigger an automatic cleaning program or prompt the replacement of the filter element in the working fluid buffer tank. Through this comprehensive and multi-level safety management and working fluid maintenance measures, the system ensures that the coupled system maintains structural integrity and performance stability over an operating cycle of more than 20 years.

[0072] The interstage heat exchanger 2 adopts a high-efficiency finned tube or plate-fin structure, and its material is selected from high-pressure resistant and high thermal conductivity alloy steel, aiming to minimize air-side flow resistance while maximizing heat exchange area. The evaporator of the high-temperature heat pump unit 3 is directly integrated into the shell of the interstage heat exchanger 2, or tightly coupled through a short-distance insulated pipeline to reduce heat loss during energy transfer. The working fluid ratio inside the heat pump unit has been specially optimized, selecting a non-azeotropic working fluid that matches the waste heat temperature range of the compressed air interstage, and utilizing its glide temperature characteristics to further reduce heat loss during heat exchange. Irreversible losses; at the control level, the system obtains the temperature difference data of the inlet and outlet air of the interstage heat exchanger 2 in real time through sensors, and adjusts the working fluid flow of the high-temperature heat pump unit 3 accordingly to ensure that the outlet temperature of the compressed air after each stage of compression is precisely controlled between 40°C and 50°C, thereby maintaining the multi-stage compressor unit to operate under the optimal thermodynamic quasi-isothermal path. Through the dual means of hardware structure optimization and working fluid property matching, the energy efficiency improvement of the heat pump and the cycle efficiency of the energy storage system are deeply decoupled and optimized, significantly improving the energy output rate per unit investment of the system.

[0073] The system's coordinated scheduling and control strategy and heating auxiliary functions: The system is equipped with a central coordination and scheduling computer, which communicates in real time with the controllers of the multi-stage compressor units, high-temperature heat pump units 3, generators 8, and industrial heating interfaces 9 via a data acquisition bus. When executing grid frequency regulation commands, the computer calculates the optimal heat storage quota for the high-temperature heat storage tank 4 based on the predicted heat load demand. If the predicted future heating load is large, the system will proactively increase the operating frequency of the high-temperature heat pump units 3, utilizing surplus grid power for electro-thermal storage. When executing energy release commands, the computer accurately calculates the multi-stage expansion based on the output requirements of generators 8. The system measures the amount of heat required by the generator and dynamically adjusts the flow rate of the first control valve 12, while the remaining heat is supplied to the outside through the second control valve 13. This control strategy also includes an islanded operation mode, in which, in the event of an external power grid failure, compressed air in the gas storage tank 6 drives a multi-stage expander for black start power generation, while the stored heat energy in the high-temperature heat storage tank 4 ensures the heating needs of critical facilities. This highly intelligent and responsive collaborative scheduling and control system endows the compressed air energy storage system with the ability to serve as a core support node of the microgrid, realizing deep complementarity between electricity and heat energy carriers in both spatial and temporal dimensions.

[0074] Taking a 10MW / 40MWh compressed air energy storage power station as an example, this paper details the system's operating parameters and procedures: System initialization and equipment parameter settings: The multi-stage compressor unit adopts a three-stage centrifugal compression with a total pressure ratio of 8.0 and a rated discharge pressure of 8.2MPa; the high-temperature heat pump unit uses a high-critical-temperature working fluid with a designed heating COP of 3.5; the high-temperature heat storage tank has a volume of 500... It contains heat transfer oil as the heat storage medium, with a maximum temperature resistance of 250℃; the gas storage tank has a volume of 5000 cubic meters. Underground salt caverns or high-pressure steel pipe arrays.

[0075] Energy storage phase operation: During grid off-peak periods (such as 0:00-6:00 AM), the system activates energy storage mode. Ambient air enters the multi-stage compressor unit. The first-stage exhaust temperature is 95℃, and the second-stage exhaust temperature is 105℃. This high-temperature air flows through the interstage heat exchanger. The high-temperature heat pump unit starts up, driving the water circuit through a circulation pump. The water circuit absorbs heat from the air in the interstage heat exchanger, and after being heated to 85℃, it enters the heat pump evaporator. The heat pump consumes 1.2MW of electrical energy to amplify this heat, heating the heat transfer oil to 180℃ at its condenser end. The heated heat transfer oil enters the high-temperature heat storage tank. At this time, the inlet temperature of each stage of the compressor remains at around 35℃, proving that the interstage cooling is sufficient, and the compression power consumption is reduced by about 5% compared with the traditional air-cooling method.

[0076] Energy release phase operation: During peak grid periods (e.g., 18:00-22:00), the system initiates energy release mode. Compressed air at 8MPa in the gas storage tank is adjusted to 7MPa by a pressure reducing valve and enters the multi-stage expander. The first control valve is opened, and heat transfer oil at 180℃ is drawn from the high-temperature heat storage tank into the interstage reheater of the expander. Due to the heat pump's heat-upgrading effect, the initial temperature at the expander inlet is increased from 80℃ in the traditional system to 160℃. Under this condition, the work capacity of a single expander is increased by 12%, and the generator output power is stabilized at 10.5MW. The heat transfer oil, after heat exchange, cools down to 70℃ and flows into the low-temperature heat storage tank, awaiting the next energy storage cycle.

[0077] Collaborative heating operation mode: If it is winter and the surrounding industrial park requires saturated steam at 120℃, the system, while generating electricity, adjusts the opening of the second control valve to divert some 180℃ heat transfer oil to the industrial heating interface. The heat transfer oil exchanges heat with industrial makeup water in the heat exchanger at the interface, generating superheated steam at 1.0MPa and 180℃. Calculations show that in this mode, the system's overall energy utilization efficiency (including electricity and heat) increases from 60% in pure power generation to 82%.

[0078] During operation, if an abnormal increase in pressure is detected in the high-temperature heat storage tank, the system immediately shuts down the heat pump compressor and opens the pressure relief bypass of the working fluid buffer tank. At this time, the first control valve automatically increases the flow rate to the expander to quickly consume the excess heat energy in the tank. The generator adjusts the excitation through the automatic voltage regulator to ensure that the grid voltage does not fluctuate due to sudden changes in flow.

[0079] The solution in this embodiment improves the cycle efficiency of the power plant by 5.5 percentage points compared to conventional projects without coupled heat pumps, increases the sales revenue of high-quality industrial steam, shortens the investment payback period by 1.8 years, solves the impact of ambient temperature fluctuations on compressor efficiency, and achieves constant operating conditions throughout the year.

[0080] Finally, it should be noted that the embodiments listed above are merely one or more specific manifestations of the technical solution of this invention. Their purpose is to clearly illustrate the concept, principle, and application of this invention through specific examples, and is by no means intended to limit the scope of protection of this invention to these specific embodiments. In fact, the true value of this invention lies in its proposed technical ideas and innovations, rather than its manifestations or implementation methods.

[0081] For those skilled in the art, after thoroughly reading and understanding the technical solution of this invention, they are fully capable of making various changes, modifications, or equivalent substitutions to the specific implementation of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the range of technical parameters, optimizing the algorithm flow to improve efficiency, and replacing some technical components to achieve better compatibility or reduce costs. As long as these modified technical solutions substantially retain the technical features claimed by the original invention, that is, they can still achieve the core functions and effects of this invention, then these changes should be considered to fall within the scope of protection of the pending claims of this invention.

[0082] Furthermore, with the continuous progress and development of technology, new technical means and methods are constantly emerging, which provides ample space for further improvement and perfection of this invention. Therefore, the scope of protection of this invention should also include reasonable and foresightful improvements and extensions based on existing technology. As long as these improvements and extensions do not depart from the basic principles and core concepts of this invention, they should be considered equivalents of this invention and are equally protected by patent rights.

Claims

1. A compressed air energy storage waste heat recovery system based on heat pump coupling, characterized in that, It includes a compressor (1), an interstage heat exchanger (2), a generator (8), a high-temperature heat pump unit (3), a high-temperature heat storage tank (4), a low-temperature heat storage tank (5), a gas storage tank (6), an interstage heater (11), an expander (7), and a heating interface (9). Among them, the outlet of the compressor (1) is connected to the inlet of the gas storage tank (6) via the hot fluid side of the interstage heat exchanger (2), the outlet of the gas storage tank (6) is connected to the inlet of the expander (7) via the cold fluid side of the interstage heater (11), the output end of the expander (7) is connected to the generator (8), the cold fluid side outlet of the interstage heat exchanger (2) is connected to the evaporation side inlet of the high temperature heat pump unit (3), and the evaporation side outlet of the high temperature heat pump unit (3) is connected to the cold fluid side inlet of the interstage heat exchanger (2), forming the first closed loop; The condenser side outlet of the high-temperature heat pump unit (3) is connected to the inlet of the high-temperature heat storage tank (4). The outlet of the high-temperature heat storage tank (4) is divided into two paths. The first path is connected to the hot fluid side inlet of the interstage heater (11), and the second path is connected to the heating interface (9). The hot fluid side outlet of the interstage heater (11) is connected to the inlet of the low-temperature heat storage tank (5), and the outlet of the low-temperature heat storage tank (5) is connected to the condenser side inlet of the high-temperature heat pump unit (3), forming a second closed loop.

2. The compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 1, characterized in that, It also includes a circulating pump (10), which is installed on the pipeline between the evaporator side outlet of the high-temperature heat pump unit (3) and the cold fluid side inlet of the interstage heat exchanger (2); The first closed loop is driven by the circulating pump (10) to run the intermediate heat transfer medium. The interstage heat exchanger (2) is used to transfer the heat of the compressed gas generated by the compressor (1) to the intermediate heat transfer medium. The evaporation side of the high-temperature heat pump unit (3) is used to absorb the heat of the intermediate heat transfer medium to cause the heat pump working fluid to undergo a phase change.

3. The compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 2, characterized in that, The evaporator side of the high-temperature heat pump unit (3) is physically coupled to the interstage heat exchanger (2). The physical coupling includes integration within the same housing or connection via a pre-set length of insulated pipe, which is used to reduce heat loss during the transmission of the intermediate heat transfer medium.

4. The compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 2, characterized in that, The high-temperature heat pump unit (3) uses a non-azeotropic mixed working fluid inside; the non-azeotropic mixed working fluid is used to reduce the irreversible loss in the heat exchange process between the evaporation side and the condensation side of the high-temperature heat pump unit (3) by utilizing the slip temperature characteristics.

5. A compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 1, characterized in that, A one-way valve (14) is provided between the hot fluid side of the interstage heat exchanger (2) and the inlet of the gas storage tank (6). The one-way valve (14) is used to prevent the gas in the gas storage tank (6) from flowing back to the interstage heat exchanger (2).

6. The compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 1, characterized in that, It also includes a first control valve (12) and a second control valve (13). The first control valve (12) is located on the first path and is used to regulate the flow of heat medium to the interstage heater (11). The second control valve (13) is located on the second path and is used to regulate the flow of heat medium to the heating interface (9).

7. A compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 1, characterized in that, The heat medium fluid from the hot fluid side outlet of the interstage heater (11) flows into the low-temperature heat storage tank (5) after being cooled by heat exchange; the low-temperature heat storage tank (5) is used to temporarily store the cooled heat medium fluid, and the cooled heat medium fluid is used as the return water reference of the condenser side of the high-temperature heat pump unit (3) and input into the condenser side inlet of the high-temperature heat pump unit (3); Interstage heater (11) is used to heat the compressed gas from the gas storage tank (6) in stages; the heat source for stage heating is taken from the heat medium fluid output from the high temperature heat storage tank (4); the interstage heater (11) is used to restore the compressed gas to a preset high temperature state before entering the next stage expander (7).

8. The operation method of a compressed air energy storage waste heat recovery system based on heat pump coupling as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The compressed gas transfers the heat of compression to the evaporation side of the high-temperature heat pump unit (3) through the interstage heat exchanger (2), causing the heat pump working fluid to absorb heat and undergo a phase change. The high-temperature heat pump unit (3) compresses and upgrades the heat pump working fluid after phase change, and releases the upgraded heat to the heat medium fluid from the low-temperature heat storage tank (5) on the condenser side of the high-temperature heat pump unit (3), so that the heat medium fluid is heated and stored in the high-temperature heat storage tank (4). During the energy release phase, the heat transfer fluid in the high-temperature heat storage tank (4) is diverted to the interstage heater (11) and the heat supply interface (9) to heat the expanding gas and supply heat to the outside. The heat transfer fluid, after being cooled by the interstage heater (11), flows back to the low-temperature heat storage tank (5) as the return water reference for the condenser side of the high-temperature heat pump unit (3).

9. The operation method of a compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 8, characterized in that, During the process of diverting the heat medium fluid in the high-temperature heat storage tank (4) to the interstage heater (11) and the heating interface (9), the required reheat is calculated according to the output requirements of the expander (7), and the ratio of the heat medium flow to the interstage heater (11) and the flow to the heating interface (9) is dynamically adjusted.

10. The operation method of a compressed air energy storage waste heat recovery system based on heat pump coupling according to claim 8, characterized in that, During the process of compressing gas and transferring the heat of compression to the evaporation side of the high-temperature heat pump unit (3) through the interstage heat exchanger (2), the flow rate of the heat pump working fluid is adjusted according to the temperature difference data of the gas at the inlet and outlet of the interstage heat exchanger (2), so that the outlet temperature of the compressed gas after each stage of compression is controlled within the preset temperature range.

Images