Compressed air and compressed steam energy storage coupled composite energy storage system

Abstract

The invention discloses a composite energy storage system coupling compressed air and compressed steam energy storage, and aims to solve the problems that an existing compressed air energy storage system is large in air storage volume and high in construction cost, and a high-pressure heat storage water pressure stabilizing device is complex. Compressed air energy storage and compressed steam energy storage are combined, air is compressed and stored through the compressor, and meanwhile liquid water is heated into steam through compression heat and stored; in the peak period of electricity utilization, high-pressure air and steam do work through a turbine to generate electricity, and space-time transfer of electric energy is achieved. By coupling two energy storage technologies, the energy storage capacity is greatly improved, the system structure is simplified, and the construction cost is reduced; according to the system, the size of the gas storage is effectively reduced through high-pressure steam-water two-phase storage, meanwhile, the normal-pressure water tank is used for storing low-pressure side water, and the complexity of the system is further reduced; the system has wide application prospects in the fields of renewable energy power generation, power grid peak regulation and the like, the energy utilization efficiency is remarkably improved, and the sustainable development of energy is promoted.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a composite energy storage system that couples compressed air and compressed steam energy storage. Background Art

[0002] With the continuous growth of global energy demand and the rapid development of renewable energy, energy storage technology, as a key link between energy production and consumption, has become increasingly important. Among the various energy storage technologies, compressed air energy storage (CAES) has become a key research direction in the field of large-scale energy storage due to its mature technology, scalability, and long lifespan.

[0003] Traditional compressed air energy storage systems primarily consist of key components such as a compressor, cooler, air storage chamber, expander, and heater. Their operating principle is roughly as follows: During periods of low electricity demand, an electric motor drives the compressor to compress and cool the air in stages, storing the high-pressure air in the air storage reservoir. The heat generated during the compression process is also stored in the thermal storage system. During peak electricity demand, the high-pressure air in the air storage reservoir absorbs the heat, which then drives the expander to generate electricity, thereby achieving the spatiotemporal transfer of electrical energy.

[0004] However, traditional compressed air energy storage systems face significant challenges in their application. First, given their storage capacity, the volume of the gas storage reservoir remains large, which directly leads to high system construction costs. Gas storage construction not only requires a large amount of land resources, but also has relatively high construction and maintenance costs, which to some extent limits the widespread application of compressed air energy storage technology.

[0005] Secondly, traditional compressed air energy storage systems also face technical challenges in maintaining high-pressure hot water storage. To prevent the water from boiling, high-pressure water is often used, but this requires a complex nitrogen pressure stabilization device to maintain the high pressure. This not only increases system complexity, but also increases operational and maintenance costs, reducing overall system efficiency.

[0006] In addition to the above-mentioned problems of traditional compressed air energy storage systems, existing energy storage technologies are also constantly exploring new coupling methods to improve energy storage efficiency and reduce costs. For example, CN216841849U discloses a system that couples steam and compressed air energy storage. The system achieves the coupling of steam and compressed air through multiple low-pressure heaters, heat exchangers, compressors, expanders and other components. However, this system mainly relies on the low-pressure heaters and steam extraction of thermal power units, and its applicability to non-thermal power application scenarios is limited. In addition, the system structure is relatively complex, which increases the difficulty and cost of operation and maintenance.

[0007] Furthermore, CN118137540B proposes a method and device for energy storage that couples compressed air and water vapor cycles. This method achieves the storage and release of electrical energy through the cyclic coupling of compressed air and water vapor. While this method can improve energy storage efficiency to a certain extent, it still relies on external water resources and has high requirements for the generation and storage of water vapor, which to some extent limits its scope of application and flexibility.

[0008] A comprehensive review of existing technologies reveals that the energy storage sector still faces numerous challenges in finding more efficient, economical, and flexible energy storage solutions. Traditional compressed air energy storage systems face challenges such as high cost, bulk, and the complexity of maintaining high-pressure hot water storage. While existing coupled energy storage systems, such as steam-compressed air coupled systems and compressed air-water vapor cycle coupled systems, have improved energy storage efficiency to a certain extent, they still face limitations such as limited application scenarios, complex system structures, and high operation and maintenance costs.

[0009] To address these issues, this paper proposes a composite energy storage system that couples compressed air and compressed steam energy storage. By cleverly combining compressed air and compressed steam energy storage technologies, this system aims to increase storage capacity, reduce costs, simplify system structure, and enhance adaptability and flexibility, providing new insights and directions for the development of energy storage technology. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a composite energy storage system that couples compressed air and compressed steam energy storage, so as to solve the problems in the field of energy storage technology, especially in compressed air energy storage systems, such as limited energy storage capacity, high construction costs, and high system complexity. In the prior art, the compressed air energy storage system has a large gas storage volume under a given energy storage capacity, resulting in high construction costs; at the same time, the maintenance of high-pressure hot water requires a complex set of pressure stabilizing devices, which increases the complexity of the system and the operation and maintenance costs. In addition, although the existing coupled energy storage systems, such as steam and compressed air coupled systems and compressed air and water vapor cycle coupled systems, have improved the energy storage efficiency to a certain extent, they still have shortcomings such as limited application scenarios and complex system structures.

[0011] To solve the above technical problems, the technical solution adopted by the present invention is: a composite energy storage system that couples compressed air and compressed steam energy storage, including a compressed air energy storage module, a compressed steam energy storage module and a thermal storage oil circulation module, which are interconnected. The compressed air energy storage module and the compressed steam energy storage module are deeply coupled through a heat exchanger. After the air compressor of the compressed air energy storage module compresses the air, the compression heat generated is transferred to liquid water through its air cooler, heating the liquid water into steam, and the steam enters the steam compressor of the compressed steam energy storage module for compression. The heat generated during the compression process is absorbed by the heat transfer oil in its steam cooler and stored in the thermal storage oil circulation module.

[0012] In a preferred embodiment, the compressed air energy storage module includes a first air compressor, the outlet of the first air compressor is connected to the inlet of the first air cooler, the outlet of the first air cooler is connected to the inlet of the second air compressor, the outlet of the second air compressor is connected to the inlet of the second air cooler, and the outlet of the second air cooler is connected to the air storage reservoir; the outlet of the air storage reservoir is connected to the inlet of the first air heater through a throttle valve, the outlet of the first air heater is connected to the inlet of the first air turbine, the outlet of the first air turbine is connected to the inlet of the second air heater, and the outlet of the second air heater is connected to the inlet of the second air turbine, and a gate valve is provided between each connection.

[0013] In a preferred embodiment, the air storage reservoir in the compressed air energy storage module is used to store compressed high-pressure air. During the energy release stage, the high-pressure air is heated in stages by the first air heater and the second air heater, and then enters the first air turbine and the second air turbine respectively to generate power.

[0014] In a preferred embodiment, the compressed steam energy storage module includes a normal pressure water tank, the outlet of the normal pressure water tank is connected to the first air cooler and the second air cooler respectively through a precooler and a water pump to provide cooling water, the steam generated by the first air cooler and the second air cooler are merged and connected to the inlet of the first steam compressor, the outlet of the first steam compressor is connected to the inlet of the first steam cooler, the outlet of the first steam cooler is connected to the inlet of the second steam compressor, the outlet of the second steam compressor is connected to the inlet of the second steam cooler, and the outlet of the second steam cooler is connected to the high-pressure steam-water storage tank; the outlet of the high-pressure steam-water storage tank is connected to the inlet of the first steam heater, the outlet of the first steam heater is connected to the inlet of the first steam turbine, the outlet of the first steam turbine is connected to the inlet of the second steam heater, and the outlet of the second steam heater is connected to the inlet of the second steam turbine, and a gate valve is provided between each connection.

[0015] In a preferred embodiment, the high-pressure steam-water storage tank in the compressed steam energy storage module stores compressed high-pressure water in the form of gas-liquid two-phase. During the energy release stage, the high-pressure water is heated in stages by the first steam heater and the second steam heater to become steam, and enters the first steam turbine and the second steam turbine respectively to generate power.

[0016] In a preferred embodiment, the atmospheric pressure water tank in the compressed steam energy storage module is used to store liquid water condensed from the high-pressure steam-water storage tank after the first steam turbine and the second steam turbine perform work in stages, and serves as a cooling water source for the first steam compressor and the second steam compressor.

[0017] In a preferred solution, the heat storage oil circulation module includes a low-temperature oil tank, the outlet of which is connected to the first steam cooler and the second steam cooler respectively through an oil pump to provide a cooling medium, the high-temperature oil outlets of the first steam cooler and the second steam cooler are merged and connected to the high-temperature oil tank, and the outlet of the high-temperature oil tank is connected to the first steam heater and the second steam heater respectively to provide a heating medium, and a gate valve is provided between each connection.

[0018] In a preferred solution, the low-temperature oil tank in the thermal storage oil circulation module stores the cooled thermal oil, which is pumped into the first steam cooler and the second steam cooler by an oil pump to absorb heat and become high-temperature thermal oil, and then enters the first steam heater and the second steam heater to release heat for heating steam.

[0019] In a preferred embodiment, the first air turbine, the second air turbine, the first steam turbine and the second steam turbine are all expanders, which are used to convert the internal energy of high-pressure air and high-pressure steam into mechanical energy and then into electrical energy.

[0020] In a preferred embodiment, during the off-peak period of electricity consumption, the system compresses the air in stages through the first air compressor and the second air compressor, cools the air, and stores it in the air storage reservoir. At the same time, the compression heat is used to heat the liquid water into steam and store it in the high-pressure steam-water storage tank. During the peak period of electricity consumption, the high-pressure air and steam are respectively generated through the first air turbine, the second air turbine, the first steam turbine, and the second steam turbine to generate electricity.

[0021] In a preferred embodiment, the system also includes a control module, which is connected to the first air compressor, the second air compressor, the first air cooler, the second air cooler, the first steam compressor, the second steam compressor, the first steam cooler, the second steam cooler, the first air heater, the second air heater, the first steam heater, the second steam heater, the first air turbine, the second air turbine, the first steam turbine, the second steam turbine, the oil pump and other key equipment and sensors in the system, and is used to monitor and control the operating status of these equipment and sensors in real time, including but not limited to monitoring of parameters such as temperature, pressure, flow, and control operations such as equipment start and stop, power regulation, etc.

[0022] In a preferred solution, the control module includes preset control algorithms and logic to adjust and optimize the system. The control module also has fault diagnosis and early warning functions to detect and handle abnormal situations in system operation.

[0023] The present invention provides a composite energy storage system that couples compressed air and compressed steam energy storage, which has the following beneficial effects: 1. This invention optimizes the system architecture by coupling compressed steam energy storage technology. Under the same energy storage capacity requirement, it effectively reduces the volume of the gas storage reservoir and reduces construction investment. It adopts a high-pressure steam-water two-phase storage method to greatly reduce the high-pressure water storage volume, simplify the pressure stabilization device, reduce system complexity, and further save construction costs.

[0024] 2. The present invention adopts the coupling method of compressed steam energy storage and compressed air energy storage to simplify the system structure, reduce the number and complexity of equipment; the application of intelligent control modules realizes automated and intelligent operation, reduces dependence on manual operation and maintenance, and thus reduces the difficulty and cost of operation and maintenance.

[0025] 3. The composite energy storage system architecture of the present invention realizes the coordinated work of the two energy storage methods in the energy storage, conversion and release processes through reasonable layout and equipment configuration, overcoming the shortcomings of the existing coupled energy storage system in limited application scenarios and can be applied to more different energy storage demand scenarios.

[0026] 4. The introduction of the staged compression intermediate cooling and staged expansion intermediate reheating technology of the present invention, as well as the in-depth optimization of the thermodynamic process, accurately controls the compression ratio, expansion ratio, cooling temperature and heating temperature and other parameters of each stage, significantly improving the energy conversion efficiency of the system.

[0027] 5. The refined design of the multi-stage compression, cooling, expansion and heating processes of the present invention enables the system to store more energy in the same volume and improve the energy storage density.

[0028] 6. The provision of a heat exchanger in the thermal storage oil circulation module of the present invention enables efficient recovery and reuse of waste heat from the thermal oil, further improving the overall thermal energy utilization efficiency of the system.

[0029] 7. The intelligent control module of the present invention has real-time monitoring, fault diagnosis and early warning functions, which can promptly detect and handle abnormal conditions in system operation, ensure the safe and stable operation of the system, and greatly improve the reliability and safety of the system.

[0030] 8. The composite energy storage system of the present invention has a flexible structure and can be flexibly adjusted according to changes in energy demand and system scale; the intelligent control module has a high degree of flexibility and adaptability, and can adjust the system's operating strategy and control parameters in real time according to factors such as changes in grid load, equipment status, and environmental conditions, ensuring that the system is always in the optimal working state.

[0031] 9. The system design of the present invention fully considers modularity and scalability, and can flexibly adjust the compression and expansion levels according to changes in energy demand and system scale to achieve rapid expansion and upgrading of the system.

[0032] 10. The present invention realizes the recycling of thermal energy through the heat storage oil circulation module, thereby reducing energy waste; the optimized system can adjust the heat energy recovery and utilization strategy according to actual needs, such as adjusting the heat exchange area of the heat exchanger, the flow rate of the thermal oil and other parameters to adapt to the operating requirements under different working conditions, thereby further reducing energy waste.

[0033] 11. The intelligent control module of the present invention can formulate the optimal energy storage and release strategy according to the grid load forecast and energy storage demand, thereby maximizing the system efficiency.

[0034] 12. The present invention rationally utilizes the recovered waste heat to reduce the operating cost of the system; while reducing energy waste and operating costs, it also reduces the negative impact on the environment. Its technical effects have been fully verified through detailed system design, simulation and actual operation tests, and it has significant technical advantages and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the layout of the composite energy system according to Example 1 of the present invention; Figure 2 This is a schematic diagram of the layout of the composite energy system according to embodiment 2 of the present invention; In the figure: the first air compressor 1, the first air cooler 3, the second air compressor 5, the second air cooler 7, the air storage reservoir 9, the throttle valve 10, the first air heater 11, the first air turbine 13, the second air heater 15, the second air turbine 17, the atmospheric water tank 22, the precooler 24, the water pump 25, the first steam compressor 30, the first steam cooler 32, the second steam compressor 34, the second steam cooler 36, the high-pressure steam-water storage tank 38, the first steam heater 40, the first steam turbine 42, the second steam heater 44, the second steam turbine 46, the low-temperature oil tank 51, the oil pump 52, the high-temperature oil tank 57, the air compression cooling unit 58, the air expansion heating unit 59, the steam expansion heating unit 60, and the steam compression cooling unit 61. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention are further described below with reference to the accompanying drawings and embodiments: Example 1 like Figure 1 As shown, this embodiment describes in detail the specific implementation of the system for coupling compressed air energy storage and compressed steam energy storage proposed by the present invention.

[0037] 1. System Structure 1. Compressed air energy storage module The first air compressor 1 and the second air compressor 5 use high-efficiency electric compressors with multi-stage compression function to improve compression efficiency and reduce energy consumption; according to the working parameters required by the system design, the working pressure range of the compressor is 150~250kPa, and the outlet air temperature is 250~350℃.

[0038] The first air cooler 3 and the second air cooler 7 use shell and tube heat exchangers with good heat exchange efficiency and corrosion resistance. The working medium uses cooling water or refrigerant to absorb the heat generated during the air compression process and reduce the air temperature to a range suitable for storage (25-35°C).

[0039] Gas storage reservoir 9: uses a high-pressure metal gas storage tank with a design pressure that matches the compressor outlet pressure; the capacity is determined based on the system energy storage requirements to ensure that sufficient high-pressure air can be stored for use in the energy release stage.

[0040] Throttle valve 10: uses a precision regulating valve to accurately control the air flow to meet different energy release requirements.

[0041] The first air heater 11 and the second air heater 15 use shell and tube or plate heat exchangers with good heating efficiency and thermal response speed; the working medium uses high-temperature thermal oil or steam to heat the air before it enters the air turbine, thereby improving the turbine's work efficiency.

[0042] The first air turbine 13 and the second air turbine 17 use high-efficiency axial-flow or centrifugal turbines, which can convert the thermal energy of high-pressure air into mechanical energy and generate electricity. The operating parameters are determined according to the system design requirements. The inlet pressure and temperature of the turbine must match the outlet parameters of the compressor and heater.

[0043] 2. Compression steam energy storage module Atmospheric pressure water tank 22: Made of stainless steel or carbon steel, it has good corrosion resistance and sealing properties; its capacity is determined according to the system energy storage requirements to ensure that it can store enough liquid water for use in the steam generation stage.

[0044] Precooler 24: A shell and tube or plate heat exchanger is used to precool the liquid water to reduce energy consumption in the subsequent heating process.

[0045] Water pump 25: A high-efficiency centrifugal pump or screw pump is used to pump liquid water to the cooler and steam compressor. The operating parameters are determined according to the system design requirements. The operating pressure and flow rate of the pump must match the steam generation and storage process.

[0046] The first steam compressor 30 and the second steam compressor 34 use multi-stage compression steam compressors to increase the pressure and temperature of the steam and increase the energy storage density. The operating parameters are determined according to the system design requirements. The inlet pressure and temperature of the compressor must match the outlet parameters of the water pump and cooler.

[0047] The first steam cooler 32 and the second steam cooler 36 are shell and tube or plate heat exchangers used to cool the compressed steam and recover heat to the thermal storage oil circulation module.

[0048] High-pressure steam-water storage tank 38: uses a high-pressure metal storage tank with a design pressure that matches the outlet pressure of the steam compressor; stores high-pressure water in the form of gas and liquid, reducing the volume of the gas storage reservoir and lowering construction costs.

[0049] The first steam heater 40 and the second steam heater 44 are shell and tube or plate heat exchangers used to heat the steam before it enters the steam turbine to improve the turbine's work efficiency.

[0050] The first steam turbine 42 and the second steam turbine 46 are high-efficiency axial flow or centrifugal turbines, which can convert the thermal energy of steam into mechanical energy and generate electricity.

[0051] 3. Thermal oil circulation module Low-temperature oil tank 51: Made of stainless steel or carbon steel, it has good corrosion resistance and sealing properties; the capacity is determined according to the system heat recovery requirements to ensure that it can store enough low-temperature thermal oil for use in the heating and cooling processes.

[0052] Oil pump 52: A high-efficiency centrifugal pump or a screw pump is used to pump the thermal oil to the cooler and heater.

[0053] High-temperature oil tank 57: A metal storage tank with good thermal insulation performance is used to reduce heat loss; the capacity is determined according to the system's heat storage requirements to ensure that sufficient high-temperature thermal oil can be stored for use in the energy release stage.

[0054] 2. Workflow 1. Energy storage stage Air compression and cooling: Air at normal pressure and temperature enters the first air compressor 1 for initial compression, with the outlet air temperature at 250-350°C and the pressure at 150-250 kPa. The compressed air enters the first air cooler 3 for cooling, with the outlet air temperature at 25-35°C, and then enters the second air compressor 5 for further compression. The air after secondary compression enters the second air cooler 7 for cooling again, and finally the high-pressure air (temperature at 25-35°C and pressure at 150-250 kPa) is stored in the gas storage reservoir 9.

[0055] Steam generation and storage: Liquid water flows out from the atmospheric water tank 22, is pre-cooled by the pre-cooler 24, and is pressurized to an appropriate pressure range by the water pump 25; the pressurized water is divided into two paths, entering the first air cooler 3 and the second air cooler 7 respectively, absorbing the heat generated during the air compression process and evaporating into steam; the steam enters the first steam compressor 30 for preliminary compression and temperature increase, and is then cooled by the thermal oil through the first steam cooler 32, and part of the heat is recovered to the thermal storage oil circulation module; the cooled steam enters the second steam compressor 34 again for further compression, and is condensed back into liquid by the thermal oil through the second steam cooler 36, and finally the liquid water is stored in the high-pressure steam-water storage tank 38 in the form of gas-liquid two-phase.

[0056] 2. Energy release stage Air energy release and power generation: High-pressure air flows out of the gas storage reservoir 9, passes through the throttle valve 10 to control the flow rate, and then enters the first air heater 11 for heating; the heated air enters the first air turbine 13 to generate power, with the outlet air temperature being -10~10℃ and the pressure being 80~180kPa; the air after generating power enters the second air heater 15 again for heating, enters the second air turbine 17 to generate power again, and is discharged into the atmosphere.

[0057] Steam energy release and power generation: High-pressure water flows out of the high-pressure steam-water storage tank 38, enters the first steam heater 40, absorbs heat from the high-temperature thermal oil, and then evaporates into steam; the steam enters the first steam turbine 42 to generate power, and the outlet steam temperature is 100-150°C, then enters the second steam heater 44 for further heating; the heated steam enters the second steam turbine 46 to generate power again, and the outlet steam temperature drops to an exhausted state (approximately 3-6 kPa); the depressurized steam is divided into two paths, entering the second air heater 15 and the first air heater 11 respectively to heat the high-pressure air, and finally the steam condenses into liquid water and is stored in the atmospheric pressure water tank 22.

[0058] Heat recovery and circulation: The heat transfer oil in the first steam cooler 32 and the second steam cooler 36 absorbs the heat of steam compression and heats up to a high temperature state, and is stored in the high-temperature oil tank 57; in the energy release stage, the high-temperature heat transfer oil flows out of the high-temperature oil tank 57, passes through the first steam heater 40 and the second steam heater 44, and releases heat for heating steam; the temperature of the heated heat transfer oil decreases and flows back to the low-temperature oil tank 51 to be prepared for the next cycle.

[0059] Through the above detailed description, the technical solution of this embodiment is more comprehensively demonstrated, and professional and technical personnel in the same technical field can successfully reproduce the technical solution of the present invention based on this description alone.

[0060] Example 2 In another preferred embodiment, Figure 2 As shown, based on Example 1, a series of advanced thermodynamic cycle units are introduced to achieve a significant improvement in system energy efficiency and energy storage density.

[0061] 1. System Structure like Figure 2 As shown, this embodiment, based on Example 1, specifically adds units including: an air compression cooling unit 58, an air expansion and heating unit 59, a steam compression cooling unit 61, and a steam expansion and heating unit 60. These units work together to not only achieve staged compression intermediate cooling and staged expansion intermediate reheating of air, but also complete a similar process for steam, thereby constructing a highly efficient and flexible energy storage and conversion system.

[0062] Air compression cooling unit 58: Located in the air compression path, it is responsible for removing the heat generated during the air compression process, ensuring that the air maintains a suitable temperature before entering the next stage of compression, thereby reducing compression power consumption.

[0063] Air expansion heating unit 59: During the energy release phase, the air before expansion is preheated using an external heat source or heat recovered from within the system to improve the working efficiency of the air turbine.

[0064] Steam compression cooling unit 61: performs preliminary compression and cooling on the steam formed after the evaporation of liquid water, in preparation for the subsequent high-pressure steam compression, while recovering part of the heat for preheating or other parts of the system.

[0065] Steam expansion heating unit 60: heats the steam before the steam turbine to increase the enthalpy of the steam and improve the output power and efficiency of the steam turbine.

[0066] 2. Workflow 1. Energy storage stage Air compression and cooling: The air is first compressed by the first air compressor 1, and then enters the air compression cooling unit 58 for re-compression and cooling to remove the compression heat, and is finally stored in the air storage reservoir 9.

[0067] Water Evaporation and Steam Compression: After pre-cooling and pressurization, liquid water is divided into two paths. One path enters the air compression cooling unit 58, where it evaporates into steam by absorbing the heat released during the air compression process. The other path enters the first air cooler 3, where it also evaporates by absorbing heat. The generated steam then enters the steam compression cooling unit 61 for initial compression and cooling. It is then further compressed to a high pressure by the second steam compressor 34. After cooling, it is stored in the high-pressure steam-water storage tank 38 in a gas-liquid two-phase form.

[0068] 2. Energy release stage Air Expansion and Power Generation: High-pressure air flows from the air storage reservoir 9, passes through the throttle valve 10 for pressure reduction, and then enters the air expansion and heating unit 59 for preheating. It then enters the second air turbine 17 to generate power. During this process, the air undergoes multiple heating and expansion steps in the second air heater 15 and the air expansion and heating unit 59 to improve overall system efficiency.

[0069] Steam Expansion and Power Generation: High-pressure water flows from the high-pressure steam-water storage tank 38, is heated by the first steam heater 40 and the steam expansion heating unit 60, and then enters the first steam turbine 42 to generate power. The reduced-pressure steam is then used to heat the high-pressure air, achieving cascaded energy utilization.

[0070] Steam condensation and recovery: Finally, the steam is condensed into liquid water in the condenser and stored in the atmospheric pressure water tank 22, completing the energy recycling.

[0071] This embodiment, by introducing advanced thermodynamic cycle units and optimized workflows, not only improves the overall efficiency of the system, but also enhances the flexibility and adaptability of the system, providing a feasible technical solution for large-scale energy storage and efficient utilization.

[0072] Example 3 In another preferred embodiment, based on Example 2, this embodiment makes key optimizations to the thermal oil circulation module to further improve the recovery and utilization efficiency of thermal energy. Specific improvements include: 1. System Structure Separate high-temperature and low-temperature oil tanks: The original high-temperature oil tank 57 is retained to store high-temperature thermal oil, while a new low-temperature oil tank is added to store low-temperature thermal oil. This separation design helps clarify the storage and recovery paths of thermal energy and improve the system's thermal management efficiency.

[0073] Heat exchanger: A heat exchanger is installed between the high-temperature oil tank 57 and the low-temperature oil storage tank. Made of high-efficiency heat transfer materials, the heat exchanger ensures sufficient heat exchange between the high-temperature thermal oil and the low-temperature thermal oil, while maintaining physical isolation between the two to prevent mixing.

[0074] Improvements to the thermal oil circulation system: Optimizing the thermal oil circulation path ensures that high-temperature thermal oil quickly returns to the high-temperature oil tank 57 after releasing heat, while low-temperature thermal oil absorbs heat and flows smoothly into the next heating or use phase. The circulation system is equipped with precise flow control and temperature monitoring devices to ensure stable operation and efficient heat exchange.

[0075] 2. Workflow 1. Energy storage stage Compression and storage of air and steam: Similar to Example 2, air and steam are compressed and cooled in stages and then stored in the air storage reservoir 9 and the high-pressure steam-water storage tank 38 respectively.

[0076] Recovery of steam compression heat: The heat generated during the steam compression process is transferred to the heat storage oil tank 57 through the heat transfer oil for storage; at this time, the temperature of the heat transfer oil in the heat storage oil tank 57 rises and becomes high-temperature heat transfer oil.

[0077] 2. Energy release stage Power generation by high-pressure air and high-pressure water: After being heated and expanded, the high-pressure air and high-pressure water enter the second air turbine 17 and the first steam turbine 42 respectively to generate power.

[0078] Waste heat recovery of thermal oil: High-temperature thermal oil flows out of the thermal oil storage tank 57 and enters the heat exchanger; in the heat exchanger, the high-temperature thermal oil exchanges heat with the low-temperature thermal oil flowing out of the low-temperature thermal oil storage tank; the high-temperature thermal oil releases heat to the low-temperature thermal oil, and after its own temperature drops, it returns to the thermal oil storage tank 57; after absorbing heat, the low-temperature thermal oil rises in temperature to become medium-temperature or high-temperature thermal oil (the specific temperature depends on the heat exchange efficiency), which can be used in other occasions requiring heating (such as preheating air, steam or as domestic hot water, etc.), or enter the next cycle to continue participating in heat energy recovery and utilization.

[0079] Steam condensation and water recovery: Similar to Example 2, the steam is condensed into liquid water in the condenser and then stored in the atmospheric pressure water tank 22.

[0080] This example further enhances the thermal energy recovery and utilization efficiency of the composite energy storage system by optimizing the thermal oil circulation module, introducing a heat exchanger, and improving the thermal oil circulation system. This system not only inherits the advantages of Examples 1 and 2 (such as large energy storage capacity, low construction costs, high system efficiency, and strong adaptability), but also achieves significant improvements in system efficiency and further optimizes energy utilization through technological innovation. This improvement opens up broader prospects for the application of composite energy storage technology in the large-scale storage and efficient utilization of renewable energy.

[0081] Example 4 In another preferred embodiment, based on embodiments 1, 2, and 3, this embodiment describes in detail a composite energy storage system for coupling compressed air and compressed steam energy storage with an integrated intelligent control module of the present invention.

[0082] 1. System Structure Building on the work of Examples 1, 2, and 3, this example introduces an advanced intelligent control module to enable comprehensive monitoring and intelligent regulation of the entire composite energy storage system. Serving as the system's "brain," the intelligent control module coordinates the operating states of various components, optimizes system efficiency, and ensures safe and stable operation.

[0083] Intelligent Control Module: This module consists of a high-performance processor, a data acquisition and transmission unit, a control algorithm execution unit, and a fault diagnosis and early warning unit. It connects to key devices and sensors in the system to obtain real-time system operating status data, such as temperature, pressure, and flow, and accurately controls and adjusts the system based on pre-set control algorithms and logic.

[0084] Data Acquisition and Transmission Unit: This unit is responsible for collecting data from various sensors, performing preliminary processing, and transmitting it to the control algorithm execution unit. This unit uses high-speed, high-precision data acquisition technology to ensure data accuracy and real-time performance.

[0085] Control Algorithm Execution Unit: Based on collected data, it uses advanced control algorithms (such as PID (Proportional-Integral-Derivative) control and fuzzy control) to optimize and control the system. This maximizes system efficiency by adjusting the operating parameters of equipment such as the air compressor, steam compressor, heater, and turbine.

[0086] Fault Diagnosis and Early Warning Unit: This unit monitors the system's operating status in real time. Once an anomaly or potential fault is detected, it immediately issues an early warning signal and takes appropriate countermeasures. By analyzing system data, this unit can accurately determine the type and location of the fault, providing strong support for rapid repairs and system restoration.

[0087] 2. Workflow 1. Energy storage stage Intelligent Regulation: The intelligent control module formulates the optimal energy storage strategy based on grid load forecasts and energy storage requirements. For example, during periods of low power, the module intelligently regulates the operating power and number of stages of air and steam compressors to achieve the most efficient energy conversion and storage.

[0088] Data acquisition and monitoring: The data acquisition and transmission unit collects the operating status data of each device in real time, such as the inlet and outlet pressures and temperatures of the air compressor and steam compressor, the pressure of the gas storage reservoir and high-pressure steam-water storage tank, etc., and transmits the data to the control algorithm execution unit.

[0089] Optimization and Adjustment: The control algorithm execution unit uses the control algorithm to optimize the system based on the collected data. For example, it can adjust the cooling water volume of air coolers and steam coolers to maintain the optimal working state of equipment and systems.

[0090] 2. Energy release stage Intelligent Scheduling: The intelligent control module intelligently schedules the release sequence and power of high-pressure air and high-pressure steam according to the grid load demand. For example, during peak power periods, high-pressure air is released first for power generation to meet the urgent needs of the grid.

[0091] Real-time monitoring and early warning: The data acquisition and transmission unit continuously collects real-time operating status data from each device and transmits it to the control algorithm execution unit. The fault diagnosis and early warning unit monitors the system's operating status in real time. If an anomaly or potential fault is detected, it immediately issues an early warning signal and takes appropriate countermeasures.

[0092] Efficient power generation: By optimizing the heating power and number of stages of the air and steam heaters, high-pressure air and steam are efficiently expanded to generate power. The intelligent control module also regulates the circulation path and flow rate of the thermal oil to improve heat recovery and utilization efficiency.

[0093] This embodiment, through the introduction of an intelligent control module, achieves comprehensive monitoring and intelligent regulation of the entire composite energy storage system. This intelligent control module not only improves the system's operational efficiency and reliability, but also reduces operating and maintenance costs. Furthermore, by implementing fault diagnosis and early warning capabilities, the system's safety and stability are further enhanced. This innovation provides a more intelligent, efficient, and reliable solution for the application of composite energy storage technology in the large-scale storage and efficient utilization of renewable energy.

[0094] In a preferred embodiment, the compressed air energy storage module includes a first air compressor 1, the outlet of the first air compressor 1 is connected to the inlet of the first air cooler 3, the outlet of the first air cooler 3 is connected to the inlet of the second air compressor 5, the outlet of the second air compressor 5 is connected to the inlet of the second air cooler 7, and the outlet of the second air cooler 7 is connected to the air storage reservoir 9; the outlet of the air storage reservoir 9 is connected to the inlet of the first air heater 11 through a throttle valve (10), the outlet of the first air heater 11 is connected to the inlet of the first air turbine 13, the outlet of the first air turbine 13 is connected to the inlet of the second air heater 15, and the outlet of the second air heater 15 is connected to the inlet of the second air turbine 17, and gate valves are provided between each connection; the above arrangement ensures efficient flow and thermal energy management of compressed air during energy storage and release, and the arrangement of the gate valve facilitates system maintenance and regulation. The outlet of the second air turbine 17 is connected to the electric generator to convert mechanical energy into electrical energy output, thereby realizing closed-loop operation of the entire compressed air energy storage system.

[0095] In the preferred embodiment, the air reservoir 9 in the compressed air energy storage module is used to store compressed high-pressure air. During the energy release phase, the high-pressure air is heated in stages by the first air heater 11 and the second air heater 15, respectively, before entering the first air turbine 13 and the second air turbine 17 to generate power. This arrangement effectively improves the energy utilization rate of the compressed air. Furthermore, the staged heating method avoids thermal stress damage that may occur when the high-pressure air is directly heated at high temperatures, ensuring the stability and safety of the system's operation. Furthermore, the ingenious design of the air reservoir 9 effectively balances compressed air pressure fluctuations, further enhancing the efficiency and reliability of the entire energy storage system.

[0096] In a preferred embodiment, the compressed steam energy storage module includes a normal pressure water tank 22, the outlet of the normal pressure water tank 22 is connected to the first air cooler 3 and the second air cooler 7 through a precooler 24 and a water pump 25 respectively to provide cooling water, the steam generated by the first air cooler 3 and the second air cooler 7 is combined and connected to the inlet of the first steam compressor 30, the outlet of the first steam compressor 30 is connected to the inlet of the first steam cooler 32, the outlet of the first steam cooler 32 is connected to the inlet of the second steam compressor 34, the outlet of the second steam compressor 34 is connected to the inlet of the second steam cooler 36, and the second steam compressor 36 is connected to the inlet of the second steam cooler 36. The outlet of the steam cooler 36 is connected to the high-pressure steam-water storage tank 38; the outlet of the high-pressure steam-water storage tank 38 is connected to the inlet of the first steam heater 40, the outlet of the first steam heater 40 is connected to the inlet of the first steam turbine 42, the outlet of the first steam turbine 42 is connected to the inlet of the second steam heater 44, and the outlet of the second steam heater 44 is connected to the inlet of the second steam turbine 46, and gate valves are provided between each connection; the above settings realize efficient compression and energy storage of steam, and improve energy conversion efficiency through multi-stage cooling and heating cycles. At the same time, the setting of the gate valves ensures flexible regulation and safe operation of the system.

[0097] In the preferred solution, the high-pressure steam-water storage tank 38 in the compressed steam energy storage module stores compressed high-pressure water in the form of gas-liquid two-phase. During the energy release stage, the high-pressure water is heated in stages by the first steam heater 40 and the second steam heater 44 to become steam, and enters the first steam turbine 42 and the second steam turbine 46 respectively to generate power. The above arrangement greatly improves the energy conversion efficiency. At the same time, during the energy storage stage, the pressure and temperature in the high-pressure steam-water storage tank are kept stable through a precise control system, thereby further optimizing the operating efficiency and stability of the entire system.

[0098] In the preferred embodiment, the atmospheric pressure water tank 22 in the compressed steam energy storage module is used to store liquid water condensed from the high-pressure steam-water storage tank 38 after the first steam turbine 42 and the second steam turbine 46 perform work in stages, and serves as a source of cooling water for the first steam compressor 30 and the second steam compressor 34. The above arrangement realizes efficient utilization and circulation of energy. At the same time, the cooling water in the atmospheric pressure water tank 22 cools the compressor through the heat exchange system, ensuring the stable operation of the system and further improving the overall efficiency and reliability of the compressed steam energy storage module.

[0099] In the preferred solution, the heat storage oil circulation module includes a low-temperature oil tank 51, the outlet of the low-temperature oil tank 51 is connected to the first steam cooler 32 and the second steam cooler 36 respectively through an oil pump 52 to provide a cooling medium, the high-temperature oil outlets of the first steam cooler 32 and the second steam cooler 36 are merged and connected to the high-temperature oil tank 57, the outlet of the high-temperature oil tank 57 is connected to the first steam heater 40 and the second steam heater 44 respectively to provide a heating medium, and a gate valve is provided between each connection; the above arrangement ensures efficient circulation and temperature control of the heat storage oil in the system; after the low-temperature oil absorbs the steam heat and heats up in the cooler, it converges and flows into the high-temperature oil tank; then, the high-temperature oil is distributed to the heater to release heat, and through the precise control of the gate valve, flexible heat management and stable operation of the system are achieved.

[0100] In the preferred solution, the low-temperature oil tank 15 in the heat storage oil circulation module stores the cooled heat-conducting oil, which is pumped into the first steam cooler 32 and the second steam cooler 36 by the oil pump 52 to absorb heat and become high-temperature heat-conducting oil, and then enters the first steam heater 40 and the second steam heater 44 to release heat for heating steam; the above arrangement enables the efficient utilization of heat energy and the cycle is repeated; after the high-temperature heat-conducting oil completes the heat release, it is cooled again and returned to the low-temperature oil tank 15, forming a closed-loop heat energy conversion system, which effectively improves the overall energy utilization efficiency.

[0101] In the preferred embodiment, the first air turbine 13, the second air turbine 17, the first steam turbine 42 and the second steam turbine 46 are all expanders, which are used to convert the internal energy of high-pressure air and high-pressure steam into mechanical energy and then into electrical energy; the above settings effectively improve the efficiency of the entire energy conversion system; in addition, the precise thermodynamic cycle design between the turbines realizes energy cascade utilization, further improving the comprehensive utilization rate of energy.

[0102] In the preferred solution, during the off-peak period of electricity consumption, the system compresses the air in stages through the first air compressor 1 and the second air compressor 5, cools the air, and stores it in the air storage reservoir 9. At the same time, the compression heat is used to heat the liquid water into steam and store it in the high-pressure steam-water storage tank 38. During the peak period of electricity consumption, the high-pressure air and steam are respectively generated through the first air turbine 13, the second air turbine 17, the first steam turbine 42, and the second steam turbine 46 to generate electricity. The above settings not only realize the efficient storage and conversion of energy, but also effectively balance the grid load and improve energy utilization. In addition, the system is equipped with an intelligent control system that can flexibly adjust the release amount of compressed air and steam according to real-time electricity demand, thereby ensuring stable power supply and reducing energy waste.

[0103] In a preferred embodiment, the system further includes a control module, which is connected to the first air compressor 1, the second air compressor 5, the first air cooler 3, the second air cooler 7, the first steam compressor 30, the second steam compressor 34, the first steam cooler 32, the second steam cooler 36, the first air heater 11, the second air heater 15, the first steam heater 40, the second steam heater 44, the first air turbine 13, the second air turbine 17, the first steam turbine 42, the second steam turbine 46, the oil pump 52 and other key equipment and sensors in the system, and is used to monitor and control the operating status of these equipment and sensors in real time, including but not limited to monitoring of parameters such as temperature, pressure, and flow, as well as control operations such as equipment start-up and shutdown, and power regulation. The above settings greatly improve the system's automation level and operating efficiency, ensuring that the entire system operates stably in the optimal state. At the same time, the control module can also automatically adjust the operating strategy based on real-time monitoring data to cope with various changes in operating conditions, thereby maximizing energy utilization and minimizing cost control.

[0104] In the preferred solution, the control module includes preset control algorithms and logic to adjust and optimize the system. The control module also has fault diagnosis and early warning functions to detect and handle abnormal conditions during system operation. The above settings ensure the efficient and stable operation of the system. At the same time, the control module can record and analyze data in real time, providing a scientific basis for further optimization and maintenance of the system, greatly improving the reliability and safety of the system.

[0105] In summary, the present invention focuses on the existing energy storage technology, especially the compressed air energy storage system, which has limited energy storage capacity, high construction cost, and high system complexity, and conducts innovative research. In view of the large volume of the gas storage reservoir of the existing compressed air energy storage system, the high construction and operation and maintenance costs caused by the need for complex pressure stabilization devices to maintain high-pressure hot water storage, and the shortcomings of the existing coupled energy storage system, such as limited application scenarios and complex system structure, although the energy storage efficiency is improved, a series of new solutions are proposed: for the first time, compressed air energy storage and compressed steam energy storage technology are coupled to construct a new composite energy storage system, so as to achieve complementary advantages and collaborative work of different energy storage methods, and open up new ways for large-scale energy storage; introduce staged compression and intermediate cooling The technology of intermediate reheating with graded expansion significantly improves the energy conversion efficiency and energy storage density of the system through the refined thermodynamic cycle design of multi-stage compression, cooling, expansion and heating; the heat storage oil circulation module is uniquely optimized, and a heat exchanger is set between the high-temperature oil tank and the low-temperature oil tank to realize the efficient recovery and reuse of the waste heat of the heat transfer oil, thereby improving the overall thermal energy utilization efficiency of the system; the intelligent control module is integrated with functions such as real-time monitoring, intelligent regulation, fault diagnosis and early warning, realizing the automation and intelligent operation of the system and improving the reliability and operation efficiency. It shows significant innovation in system architecture, thermodynamic cycle, heat storage oil circulation and intelligent control, and provides a new solution for the development of energy storage technology.

Claims

1. A composite energy storage system that couples compressed air and compressed steam energy storage, characterized by: It includes a compressed air energy storage module, a compressed steam energy storage module and a thermal storage oil circulation module, which are interconnected. The compressed air energy storage module and the compressed steam energy storage module are deeply coupled through a heat exchanger. After the air compressor of the compressed air energy storage module compresses the air, the compression heat generated is transferred to liquid water through its air cooler, heating the liquid water into steam. The steam enters the steam compressor of the compressed steam energy storage module for compression. The heat generated during the compression process is absorbed by the heat transfer oil in its steam cooler and stored in the thermal storage oil circulation module.

2. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 1 is characterized in that: The compressed air energy storage module comprises a first air compressor (1), the outlet of the first air compressor (1) is connected to the inlet of a first air cooler (3), the outlet of the first air cooler (3) is connected to the inlet of a second air compressor (5), the outlet of the second air compressor (5) is connected to the inlet of a second air cooler (7), and the outlet of the second air cooler (7) is connected to an air storage reservoir (9); the outlet of the air storage reservoir (9) is connected to the inlet of a first air heater (11) through a throttle valve (10), the outlet of the first air heater (11) is connected to the inlet of a first air turbine (13), the outlet of the first air turbine (13) is connected to the inlet of a second air heater (15), and the outlet of the second air heater (15) is connected to the inlet of a second air turbine (17), and gate valves are provided between each connection.

3. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 2, characterized in that: The air storage reservoir (9) in the compressed air energy storage module is used to store compressed high-pressure air. During the energy release phase, the high-pressure air is heated in stages by the first air heater (11) and the second air heater (15) and then enters the first air turbine (13) and the second air turbine (17) to generate power.

4. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 3 is characterized in that: The compressed steam energy storage module includes a normal pressure water tank (22), the outlet of the normal pressure water tank (22) is connected to the first air cooler (3) and the second air cooler (7) through a precooler (24) and a water pump (25) respectively to provide cooling water, the steam generated by the first air cooler (3) and the second air cooler (7) are combined and connected to the inlet of the first steam compressor (30), the outlet of the first steam compressor (30) is connected to the inlet of the first steam cooler (32), the outlet of the first steam cooler (32) is connected to the inlet of the second steam compressor (34), and the outlet of the second steam compressor (34) is connected to the inlet of the second steam compressor (34). The outlet of the steam compressor (34) is connected to the inlet of the second steam cooler (36), and the outlet of the second steam cooler (36) is connected to the high-pressure steam-water storage tank (38); the outlet of the high-pressure steam-water storage tank (38) is connected to the inlet of the first steam heater (40), the outlet of the first steam heater (40) is connected to the inlet of the first steam turbine (42), the outlet of the first steam turbine (42) is connected to the inlet of the second steam heater (44), and the outlet of the second steam heater (44) is connected to the inlet of the second steam turbine (46), and gate valves are provided between each connection.

5. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 4 is characterized in that: The high-pressure steam-water storage tank (38) in the compressed steam energy storage module stores compressed high-pressure water in the form of gas and liquid. During the energy release stage, the high-pressure water is heated in stages by the first steam heater (40) and the second steam heater (44) to become steam, and then enters the first steam turbine (42) and the second steam turbine (46) respectively to generate power.

6. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 5, characterized in that: The atmospheric pressure water tank (22) in the compressed steam energy storage module is used to store liquid water condensed from the high-pressure steam-water storage tank (38) after the first steam turbine (42) and the second steam turbine (46) perform work in stages, and serves as a cooling water source for the first steam compressor (30) and the second steam compressor (34).

7. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 6, characterized in that: The heat storage oil circulation module comprises a low-temperature oil tank (51), the outlet of the low-temperature oil tank (51) is connected to the first steam cooler (32) and the second steam cooler (36) respectively through an oil pump (52) to provide a cooling medium, the high-temperature oil outlets of the first steam cooler (32) and the second steam cooler (36) are connected to the high-temperature oil tank (57) after merging, and the outlet of the high-temperature oil tank (57) is connected to the first steam heater (40) and the second steam heater (44) respectively to provide a heating medium, and a gate valve is provided between each connection.

8. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 7, characterized in that: The low-temperature oil tank (15) in the heat storage oil circulation module stores cooled heat transfer oil, which is pumped into the first steam cooler (32) and the second steam cooler (36) by the oil pump (52) to absorb heat and then become high-temperature heat transfer oil, which then enters the first steam heater (40) and the second steam heater (44) to release heat for heating steam.

9. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 8, characterized in that: The first air turbine (13), the second air turbine (17), the first steam turbine (42) and the second steam turbine (46) are all expanders for converting the internal energy of high-pressure air and high-pressure steam into mechanical energy and then into electrical energy.

10. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 9, characterized in that: During the off-peak period of electricity consumption, the system compresses and cools the air in stages through the first air compressor (1) and the second air compressor (5) and stores it in the air storage reservoir (9). At the same time, the compression heat is used to heat liquid water into steam and store it in the high-pressure steam-water storage tank (38). During the peak period of electricity consumption, the high-pressure air and steam respectively generate electricity through the first air turbine (13), the second air turbine (17), the first steam turbine (42) and the second steam turbine (46).

11. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 10, characterized in that: The system further includes a control module, which is connected to the first air compressor (1), the second air compressor (5), the first air cooler (3), the second air cooler (7), the first steam compressor (30), the second steam compressor (34), the first steam cooler (32), the second steam cooler (36), the first air heater (11), the second air heater (15), the first steam heater (40), the second steam heater (44), the first air turbine (13), the second air turbine (17), the first steam turbine (42), the second steam turbine (46), the oil pump (52) and the sensors, and is used for real-time monitoring and control of the operating status of these devices and sensors, including but not limited to monitoring of temperature, pressure and flow, and control operations of equipment start-stop and power regulation.

12. The composite energy storage system for coupling compressed air and compressed steam energy storage according to claim 11, characterized in that: The control module includes preset control algorithms and logic to adjust and optimize the system. The control module also has fault diagnosis and early warning functions to detect and handle abnormal situations in system operation.

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