Multi-stage compressed air energy storage system for salt cavern gas storage and regulation and control method of multi-stage compressed air energy storage system

Abstract

The multistage compressed air energy storage system comprises a salt cavern air storage chamber, the inlet end of the salt cavern air storage chamber is connected with a multistage compression device and a first heat exchanger, and the outlet end of the salt cavern air storage chamber is connected with a multistage expansion power generation device and a second heat exchange device. The heat storage liquid outlet end of the first heat exchanger is connected to the heat storage liquid inlet end of the first heat exchanger through the high-temperature tank, the second heat exchange device and the low-temperature tank; the salt cavern gas storage chamber and the high-temperature tank are respectively connected with a pressure potential energy-heat energy coupling conversion device based on a Ponghua material, and the pressure potential energy-heat energy coupling conversion device is used for releasing heat energy when the pressure is increased and absorbing the heat energy when the pressure is reduced. When the compressed air energy storage system needs to store energy across months and even seasons, excess compressed air potential energy is converted into heat energy through the pressure-heat conversion device, so that potential energy output is improved, and the efficiency and economical efficiency of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of large-capacity energy storage for power system scenario applications, and specifically relates to a multi-stage compressed air energy storage system for salt cavern gas storage and a control method thereof. Background Art

[0002] Compressed Air Energy Storage (CAES) is an efficient and environmentally friendly large-scale energy storage solution. Its basic principle is to use excess electricity (such as at night when electricity consumption is low) to compress air and store the compressed air in underground caves, gas tanks or other high-pressure containers. During peak electricity consumption, the stored high-pressure air is released to generate electricity by driving turbines, thereby achieving effective storage and supply of electricity.

[0003] In order to improve the energy storage effect and energy conversion efficiency of the entire system, compressed air energy storage systems usually use multi-stage compression and multi-stage expansion technology. Multi-stage compression refers to compressing the air to the required high pressure state in multiple times. The advantage of this is that it can reduce the energy required for each compression, and it is also beneficial to control the temperature rise during the compression process. Correspondingly, multi-stage expansion refers to expanding the air to a state close to atmospheric pressure by gradually reducing the pressure when releasing high-pressure air. This can more effectively utilize the pressure potential energy of the air and improve the energy recovery rate.

[0004] During the air compression and expansion process, using thermal storage liquids (such as water, oil or other special heat storage materials) to absorb or release heat is a key measure to improve system efficiency. During the compression stage, the thermal storage liquid can absorb the heat generated during the compression process to prevent the air temperature from being too high; while during the expansion stage, the thermal storage liquid can release the previously absorbed heat to heat the air during the expansion process, which can not only increase the temperature of the air, but also increase its volume, thereby improving the work capacity and power generation efficiency of the turbine.

[0005] In addition, by precisely controlling the temperature and flow rate of the heat storage liquid, the operating conditions of the entire energy storage system can be optimized to ensure that the system can maintain a high energy conversion efficiency under different operating conditions. Therefore, the selection of heat storage liquid and its application strategy in the system have an important impact on the performance and economic benefits of the compressed air energy storage system.

[0006] However, in practical applications, compressed air energy storage technology faces some challenges, as follows: First, the heat generated during the air compression process (200-300 degrees) is relatively low, and under non-contact heat exchange conditions, the heat storage temperature will be further reduced, resulting in poor thermal energy quality. This limits the storage period of thermal energy, which is usually difficult to exceed a few weeks, thus affecting the overall energy storage period and efficiency.

[0007] Secondly, in order to achieve large-capacity energy storage, it is usually necessary to use underground salt caverns or large artificial gas storage chambers for high-pressure air storage. Although these natural or artificial conditions can meet the storage needs of high-pressure air to a certain extent, the heat storage process often requires customized processing of heat exchangers and heat storage tanks, which not only increases the cost, but also the heat storage energy is usually more than an order of magnitude smaller than the gas storage pressure potential energy, which makes the heat storage unit a bottleneck in the compressed air energy storage system.

[0008] Therefore, in the current 100-megawatt compressed air energy storage demonstration project, the limitation of the heat storage unit is particularly prominent. Since the heat storage amount and heat storage time are difficult to break through the monthly cycle, the characteristics of compressed air long-term energy storage are difficult to be effectively demonstrated. If the demand for heat storage is reduced, although the cost and complexity can be reduced, it may cause a significant drop in output power during the energy release stage, thus affecting the actual application effect of the technology.

[0009] To solve this problem, future research and development needs to focus on improving the thermal energy utilization efficiency in the compressed air energy storage process, developing more efficient heat exchangers and heat storage technologies, and exploring new energy storage materials and methods. In addition, optimizing system design and improving energy conversion efficiency are also important directions for improving the performance and competitiveness of compressed air energy storage technology. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a multi-stage compressed air energy storage system for salt cavern gas storage and a control method thereof in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problem of decreased efficiency caused by a long storage and release cycle of a high-power compressed air storage system.

[0011] The present invention adopts the following technical solutions: A multi-stage compressed air energy storage system for salt cavern gas storage comprises a salt cavern gas storage chamber, the inlet end of the salt cavern gas storage chamber is connected to a multi-stage compression device and a first heat exchanger, the outlet end of the salt cavern gas storage chamber is connected to a multi-stage expansion power generation device and a second heat exchange device, the heat storage liquid outlet end of the first heat exchanger is connected to the heat storage liquid inlet end of the first heat exchanger via a high temperature tank, a second heat exchange device and a low temperature tank; the salt cavern gas storage chamber and the high temperature tank are respectively connected to a pressure potential energy-heat energy coupling conversion device.

[0012] Preferably, the pressure potential energy-heat energy coupling conversion device comprises a device housing, one end of the device housing is provided with a converging top cover, and the other end is correspondingly provided with a diverting bottom cover, the converging top cover is provided with a heat storage liquid outlet, and the diverting bottom cover is provided with a heat storage liquid inlet; A high-pressure inlet is arranged on the side of the device housing near the converging top cover, and a low-pressure outlet is arranged on the other side of the device housing near the diverting bottom cover; A plurality of heat storage liquid pipelines are arranged inside the device shell, one end of the plurality of heat storage liquid pipelines is connected to the heat storage liquid outlet, and the other end is connected to the heat storage liquid inlet.

[0013] Preferably, a plurality of thermal storage liquid pipeline arrays are disposed within the device housing.

[0014] Preferably, composite heat-releasing structures are arranged at intervals on a plurality of heat storage liquid pipelines.

[0015] Preferably, the composite heat-releasing structure is arranged along the circumference of the device housing.

[0016] Preferably, the multi-stage compression device comprises a first compression device and a second compression device connected in sequence, and the first heat exchanger is arranged between the first compression device and the second compression device.

[0017] Preferably, the multi-stage expansion power generation device comprises a first expansion device and a second expansion device connected in sequence, and the second heat exchange device is arranged between the first expansion device and the second expansion device.

[0018] Another technical solution of the present invention is a control method for a multi-stage compressed air energy storage system for salt cavern gas storage, comprising: The air is compressed by the multi-stage compressor and the first heat exchanger to recover excess heat, and then enters the salt cavern gas storage chamber under high pressure. The heat storage liquid absorbs the heat generated by the air compression through the first heat exchanger and is transferred from the low temperature tank to the high temperature tank; or The high-pressure gas in the salt cavern gas storage chamber absorbs heat and generates power through the multi-stage expansion device and the second heat exchange device. During this period, the energy storage liquid in the high-temperature tank transfers heat energy to the working air through the second heat exchange device and then flows back to the low-temperature tank for standby.

[0019] Preferably, when there is sufficient gas in the salt cavern gas storage chamber, but the temperature of the energy storage liquid in the high-temperature tank does not meet the standard, the salt cavern gas storage chamber is connected to the pressure potential energy-thermal energy coupling conversion device to convert part of the air potential energy into thermal energy. At this time, the liquid in the high-temperature tank flows through the pressure potential energy-thermal energy coupling conversion device and then flows into the second heat exchange device.

[0020] Preferably, when the system completes the energy release phase and enters the standby state for the next energy storage cycle, the valve is adjusted to connect the pressure potential energy-thermal energy coupling conversion device to the atmosphere to restore normal pressure.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: A multi-stage compressed air energy storage system for salt cavern gas storage can decouple the matching relationship between heat storage and gas storage in the compressed air energy storage system, and compensate for or even improve the quality and total amount of heat storage by increasing the gas storage scale and pressure potential energy, so that the compressed air energy storage technology can break through the existing low-temperature liquid heat storage cycle limitations and give full play to the technical characteristics of the long-cycle and large-capacity compressed air energy storage system. The present invention can be mass-produced and applicable to all advanced multi-stage compressed air energy storage systems, which can bring significant economic benefits and technical improvements. Through this structural design and innovative operation method, the design storage-release ratio of the high-power long-time compressed air energy storage system can be dynamically adjusted, and the thermal energy-release can be flexibly adjusted according to the energy storage cycle requirements and the local climate and power grid dispatching requirements during operation. The design parameters of the pressure potential energy-heat energy coupling conversion device can be increased by expanding investment to achieve the normal operation of the compressed storage system during the maintenance or failure of the thermal cycle device.

[0022] Furthermore, by using the pressure potential energy-thermal energy coupling conversion device in the forward direction, the excess compressed air potential energy can be converted into thermal energy, which can be used to increase the output power during the energy release stage of the pressure storage system; by using the pressure potential energy-thermal energy coupling conversion device in the reverse direction, the pressure potential energy of the low-pressure air can be increased and the thermal energy during the energy storage stage can be absorbed, which can be used to reduce the energy consumption of the pressure storage system during the energy storage stage and improve the energy storage efficiency.

[0023] Furthermore, by arranging a plurality of heat storage liquid pipelines in an array inside the shell, the heat storage liquid flow rate and the heat exchange efficiency can be effectively adjusted, thereby improving the control accuracy and the maximum heat exchange capacity per unit time.

[0024] Furthermore, the composite heat release structure design enables the step-by-step utilization of thermal energy, achieving a positive sequence match between the heat storage temperature and the heat demand temperature, and improving the heat exchange efficiency and heat storage utilization rate.

[0025] Furthermore, through multi-stage compression, the heat exchange unit can be used to absorb excess heat energy of the working fluid after compression, reduce the temperature of high-pressure air, reduce compression power consumption, and improve compression energy storage efficiency.

[0026] Furthermore, through multi-stage expansion, the heat exchange unit can be used to release the stored heat, increase the temperature of the high-pressure air for energy release, improve the work capacity, and increase the total work output of the system.

[0027] A control method for a multi-stage compressed air energy storage system for salt cavern gas storage can significantly improve the output drop caused by the mismatch between stored heat energy and stored gas energy release after long-term energy storage through control.

[0028] Furthermore, when the energy storage time between storage and release is too long, resulting in sufficient gas in the salt cavern gas storage chamber, but the temperature of the energy storage liquid in the high-temperature tank does not meet the standard, the high-pressure air will be forced to do work at low temperature. Although the output time is the same, the output value of the expander is lower than the design requirement.

[0029] Furthermore, when the conversion device is enabled, the consumption of air compression potential energy can be accelerated to increase the work capacity per unit air and the system output, so that when the system completes the energy release link and enters the standby state for the next energy storage cycle, the available capacity of the air storage chamber and the temperature of the working fluid in the heat storage tank can absorb more energy.

[0030] In summary, the present invention can improve the regulation and operation freedom of the compressed air energy storage system, improve the adaptability of the operation process to long-term energy storage and the matching between the system energy storage and release elements, and improve the operation freedom and the system energy storage and release efficiency.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 It is a schematic diagram of the connection of the system of the present invention; Figure 2 It is the structural diagram of the pressure potential energy-heat energy coupling conversion device; Figure 3 Schematic diagram of operation and control of the system of the present invention.

[0034] Among them: 1. First compression device; 2. Second compression device; 3. First heat exchanger; 4. First expansion device; 5. Second expansion device; 6. Second heat exchange device; 7. Salt cavern gas storage chamber; 8. High temperature tank; 9. Low temperature tank; 10. Pressure potential energy-thermal energy coupling conversion device; 11. Device housing; 12. Composite heat release structure; 13. Heat storage liquid pipeline; 14. Heat storage liquid outlet; 15. Heat storage liquid inlet; 16. Converging top cover; 17. Diverting bottom cover; 18. High pressure inlet; 19. Low pressure outlet. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0039] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0040] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0041] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0042] The present invention provides a multi-stage compressed air energy storage system for salt cavern gas storage and a control method thereof. Based on the caloric effect, a pressure potential energy-heat energy coupling conversion device made of a caloric material is used to convert excess pressure potential energy into heat energy under long-term energy storage requirements, thereby effectively improving the energy release output and improving the performance of the compressed air energy storage system; by connecting the pressure-heat conversion device with an existing high-temperature tank, the heat storage liquid in the high-temperature tank is quickly heated by part of the air pressure potential energy, thereby restoring the air energy release output capacity; by introducing the pressure-heat conversion device and combining it with heat storage technologies such as high-temperature tanks, the performance of the compressed air energy storage system is significantly improved, especially when dealing with long-term energy storage requirements.

[0043] See also Figure 1 The present invention discloses a multi-stage compressed air energy storage system for salt cavern gas storage, comprising a first compression device 1, a second compression device 2, a first heat exchanger 3, a first expansion device 4, a second expansion device 5, a second heat exchange device 6, an air storage chamber 7, a high temperature tank 8, a low temperature tank 9 and a pressure potential energy-heat energy coupling conversion device 10.

[0044] The cold end input end of the first compression device 1 is connected to air, and the cold end output end of the first compression device 1 is connected to the input end of the air storage chamber 7 via the first heat exchanger 3 and the second compression device 2; the output end of the air storage chamber 7 is connected to the cold end input end of the second expansion device 5 via the first expansion device 4 and the second heat exchange device 6.

[0045] The hot end output end of the first heat exchanger 3 is connected to the hot end input end of the first heat exchanger 3 after passing through the high temperature tank 8, the second heat exchange device 6 and the low temperature tank 9 in sequence.

[0046] The gas storage chamber 7 and the high-temperature tank 8 are respectively connected to a pressure potential energy-thermal energy coupling conversion device 10. The pressure potential energy-thermal energy coupling conversion device 10 is based on the caloric effect and can release thermal energy when the pressure increases and absorb thermal energy when the pressure decreases.

[0047] The high temperature tank 8 is a heat storage device, which is filled with heat storage liquid. It is connected to the pressure potential energy-heat energy coupling conversion device 10, and part of the compressed air is quickly released through the device, and the released pressure potential energy is converted into heat energy to heat the heat storage liquid in the high temperature tank.

[0048] In order to improve the heat exchange efficiency, the internal structure of the high-temperature tank 8 is optimized. The optimization methods include increasing the heat exchange area, improving the liquid flow method, etc., to ensure that the pressure potential energy released by the air can be converted into heat energy to the maximum extent and stored in the heat storage liquid.

[0049] Through the pressure-heat conversion process, the heat storage liquid obtains additional thermal energy, which can play a role in the energy release stage of the compressed air energy storage system.

[0050] Specifically, when the system needs to release energy, the heat storage liquid is used to heat the compressed air that is about to expand. By heating the compressed air, its volume and temperature can be increased, thereby generating greater driving force when passing through the turbine and improving the expansion efficiency. When the heated compressed air expands in the turbine, it can push the turbine blades to rotate at a higher speed, thereby increasing the output power of the generator and increasing power generation. By effectively transferring the heat energy in the heat storage liquid to the compressed air, the energy loss in the entire energy conversion process can be reduced, thereby improving the overall energy conversion efficiency of the system.

[0051] Under long-term energy storage needs, by introducing heat storage liquid, the overall performance of the system can be improved by converting it into thermal energy without reducing the storage volume of compressed air, thereby increasing energy output without sacrificing the pressure potential energy of the stored gas, and adapting to different load requirements by heating compressed air, thereby enhancing the stability and reliability of the system. By effectively utilizing the thermal energy in the heat storage liquid, the waste in the energy conversion process is reduced, and the energy utilization efficiency of the entire energy storage system is improved, which is particularly important for large-scale, long-term energy storage applications.

[0052] The multi-stage compressed air energy storage system for salt cavern gas storage of the present invention uses air as the working medium. In the energy storage stage, the air is passed through the first compression device 1, the second compression device 2 and the first heat exchanger 3 to recover excess heat and then enter the salt cavern gas storage chamber 7 under high pressure; the heat storage liquid (usually water or heat transfer oil) passes through the first heat exchanger 3 to absorb the heat generated by air compression and then is transferred from the low temperature tank 9 to the high temperature tank 8; In the energy release stage, the high-pressure gas in the salt cavern gas storage chamber 7 absorbs heat and generates power through the first expansion device 4, the second expansion device 5 and the second heat exchange device 6. During this period, the energy storage liquid in the high-temperature tank 8 transfers heat energy to the working air through the second heat exchange device 6 and then flows back to the low-temperature tank 9 for standby.

[0053] The pressure potential energy-heat energy coupling conversion device 10 is connected to the second heat exchange device 6, the salt cavern gas storage chamber 7 and the atmosphere through pipelines, and single-side connection pressure regulation is achieved through valves on the pipelines.

[0054] See also Figure 2 The pressure potential energy-heat energy coupling conversion device 10 based on the Pangyaka material includes a device housing 11, a composite heat release structure 12, a heat storage liquid pipeline 13, a heat storage liquid outlet 14, a heat storage liquid inlet 15, a converging top cover 16, a diverting bottom cover 17, a high-pressure inlet 18 and a low-pressure outlet 19; A converging top cover 16 is provided at one end of the device housing 11, and a diverting bottom cover 17 is provided at the other end. A heat storage liquid outlet 14 is provided on the converging top cover 16, and a heat storage liquid inlet 15 is provided on the diverting bottom cover 17. A high-pressure inlet 18 is provided on the side of the device housing 11 close to the converging top cover 16, and a low-pressure outlet 19 is provided on the other side of the device housing 11 close to the diverting bottom cover 17. A plurality of heat storage liquid pipelines 13 are arranged in an array inside the device housing 11 , one end of the plurality of heat storage liquid pipelines 13 is connected to a heat storage liquid outlet 14 , and the other end is connected to a heat storage liquid inlet 15 ; a plurality of composite heat release structures 12 are arranged at intervals in the circumferential direction inside the device housing 11 .

[0055] The core of the pressure potential energy-heat energy coupling conversion device 10 is to use high-pressure gas (such as compressed air) to expand rapidly through a specific nozzle or expander, and this process is accompanied by a significant decrease in the gas temperature (i.e., adiabatic expansion); Subsequently, through heat exchange with a heat storage liquid (such as high-temperature oil or molten salt), the cold energy in the gas is transferred to the heat storage liquid, thereby increasing the temperature of the heat storage liquid and storing thermal energy. This process actually converts the pressure potential energy of the high-pressure gas into thermal energy, realizing the effective conversion of the two forms of energy.

[0056] The specific principles are as follows: Adiabatic expansion of high-pressure gas: In a compressed air energy storage system, high-pressure gas (usually compressed air) is stored in a high-pressure container or salt cavern. When the energy needs to be released, these high-pressure gases are rapidly expanded through a specific nozzle or expander. In this process, the pressure and temperature of the gas will drop significantly. This phenomenon is called adiabatic expansion. The adiabatic expansion process is fast and non-isothermal. There is no heat exchange during the expansion of the gas, so its temperature will drop sharply.

[0057] Capture and transfer of cold energy: The temperature of the gas after adiabatic expansion is very low, and the cold energy contained in this part of the low-temperature gas is a potential energy resource. In the pressure potential energy-thermal energy coupling conversion device, this low-temperature gas exchanges heat with the heat storage liquid (such as high-temperature oil or molten salt). In this way, the cold energy in the gas is transferred to the heat storage liquid, causing the temperature of the heat storage liquid to rise. This process is actually a conversion of energy forms, that is, converting the pressure potential energy of the high-pressure gas (through adiabatic expansion) into thermal energy in the heat storage liquid.

[0058] By optimizing the design of the nozzle or expander, the gas expansion process can be more effectively controlled, thereby improving the efficiency of adiabatic expansion. In addition, the selection of suitable heat storage liquid and heat exchanger materials, as well as the optimization of the structural design of the heat exchanger, can improve the energy conversion efficiency.

[0059] The design of the pressure potential energy-heat energy coupling conversion device can also consider adding a regulating valve and a bypass system to flexibly adjust the expansion path and degree of the gas according to different operating conditions and requirements, so that the system can better adapt to changing load requirements and different energy storage / release cycles.

[0060] In addition to converting cold energy into heat energy, other ways of utilizing cold energy can also be explored, such as directly using cryogenic gases for refrigeration or other application scenarios that require cold energy.

[0061] See also Figure 3 The present invention provides a control method for a multi-stage compressed air energy storage system for salt cavern gas storage, comprising the following steps: When the energy storage time between energy storage and release is too long, resulting in sufficient gas in the salt cavern gas storage chamber 7, but the temperature of the energy storage liquid in the high-temperature tank 8 does not meet the standard, the salt cavern gas storage chamber 7 is connected to the pressure potential energy-thermal energy coupling conversion device 10 to convert part of the air potential energy into thermal energy. At this time, the liquid in the high-temperature tank 8 flows through the pressure potential energy-thermal energy coupling conversion device 10 and then flows into the heat exchanger 6, thereby improving the expansion work power generation capacity of the compressed air energy storage system; Connecting the salt cavern gas storage chamber 7 with the pressure potential energy-heat energy coupling conversion device 10: By opening the corresponding valve, the salt cavern gas storage chamber 7 is connected with the pressure potential energy-heat energy coupling conversion device 10; at this time, part of the high-pressure gas converts its own pressure potential energy into heat energy through the pressure potential energy-heat energy coupling conversion device 10.

[0062] Heating the energy storage liquid in the high-temperature tank 8: The energy storage liquid that passes through the pressure potential energy-thermal energy coupling conversion device 10 increases in temperature due to absorbing the pressure potential energy of the high-pressure gas; these high-temperature liquids then flow into the heat exchanger to further increase their temperature, thereby providing sufficient thermal energy support for subsequent expansion work and power generation.

[0063] The above method not only solves the problem of insufficient temperature of the energy storage liquid in the high-temperature tank, but also improves the expansion work and power generation capacity of the compressed air energy storage system, thereby improving the overall energy utilization efficiency.

[0064] When the system completes the energy release phase and enters the standby state for the next energy storage cycle, the valve is adjusted to connect the pressure potential energy-heat energy coupling conversion device 10 to the atmosphere to restore normal pressure. At this time, the composite Pangyaka material absorbs heat energy in the ambient air to restore the initial state and meet the conditions for external cooling.

[0065] Adjust the valve to connect the pressure potential energy-heat energy coupling conversion device to the atmosphere and restore the normal pressure: by closing the valve connected to the salt cavern gas storage chamber 7 and opening the valve to the atmosphere, the pressure inside the pressure potential energy-heat energy coupling conversion device 10 gradually drops to the normal pressure state; this step helps the composite pangya card material absorb the heat energy in the ambient air and restore its initial state.

[0066] Using composite pangyaka materials to provide external cooling: During the process of the pressure potential energy-heat energy coupling conversion device returning to normal pressure, the temperature of the composite pangyaka material will decrease due to the absorption of heat energy in the ambient air, thus meeting the conditions for external cooling. This can not only provide cooling effect for the environment around the system, but also further improve the overall energy efficiency of the system.

[0067] It improves the energy conversion efficiency and energy storage / release performance of the compressed air energy storage system, and expands the application scenarios of the system, so that it can provide cold energy to the outside world while providing electrical energy, enhancing the system's comprehensive energy service capabilities.

[0068] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0069] Simulation experiment When simulating a multi-stage compressed air energy storage system for salt cavern gas storage, attention is paid to the performance of the system under different operating conditions, especially the energy conversion efficiency, the thermodynamic performance during energy storage and release, and the overall economy and feasibility of the system. Since the specific simulation results are affected by many factors, including but not limited to the efficiency of the compressor and expander, the design parameters of the heat exchanger, the characteristics of the gas storage chamber and the heat storage liquid, etc., the specific contents are as follows: System Modeling Energy conservation: During the simulation process, it is assumed that the entire system follows the law of conservation of energy, that is, at any time, the energy input to the system is equal to the output energy plus the stored energy.

[0070] Adiabatic expansion: For the expansion process of high-pressure gas, it is assumed to be adiabatic expansion, that is, the gas does not exchange heat with the outside world during the expansion process.

[0071] Ideal gas behavior: In order to simplify the calculation, it is assumed that the gases involved in energy conversion (such as compressed air) obey the ideal gas law, that is, their behavior can be well described by the ideal gas equation.

[0072] Simulation Analysis Energy conversion efficiency: Through simulation analysis, the energy conversion efficiency of the system under different operating conditions is calculated, that is, the ratio of output energy (such as electrical energy generated by the turbine) to input energy (such as the potential energy of compressed air).

[0073] Dynamic characteristics of energy storage and release processes: Through simulation, we can observe the dynamic changes of the system during the energy storage and release process, including the temperature and pressure changes of the gas storage chamber and the heat storage liquid.

[0074] System optimization suggestions: Based on the simulation results, we can identify energy loss points in the system and make corresponding optimization suggestions, such as improving the heat exchanger design, optimizing the operating conditions of the compressor and expander, etc.

[0075] Typical simulation results Energy conversion efficiency: The simulation results show that by rationally designing the multi-stage compression and expansion process and efficiently utilizing the thermal energy of the thermal storage liquid, the energy conversion efficiency of the entire system can reach a relatively high level (for example, the efficiency values ​​reported in some literature can reach more than 70%).

[0076] Stability of energy storage and release processes: Simulation results show that by introducing a pressure potential energy-thermal energy coupling conversion device, the overall performance of the system can be improved by converting the pressure potential energy of the gas storage chamber into thermal energy without sacrificing the pressure potential energy of the gas storage chamber, thereby maintaining stable operation of the system under long-term energy storage requirements.

[0077] Economic and feasibility: Although the specific economic and feasibility analysis needs to consider more actual operation and market conditions, the simulation results preliminarily show that through the optimization of design and operation strategies, the multi-stage compressed air energy storage system for salt cavern gas storage has good economic and application prospects.

[0078] Through the simulation analysis of the multi-stage compressed air energy storage system for salt cavern gas storage, we can better understand its working principle and performance characteristics, and provide theoretical support and guidance for further system optimization and practical application. It should be noted that more engineering details and market conditions need to be considered in actual operation to ensure the economy and feasibility of the system.

[0079] In summary, the multi-stage compressed air energy storage system for salt cavern gas storage and the control method thereof of the present invention are suitable for large-capacity and long-period compressed air energy storage systems, especially system devices with larger gas storage salt caverns and relatively limited capacity of heat storage units. When the compressed air energy storage system needs to store energy across months or even quarters, the excess compressed air potential energy is converted into heat energy through a pressure-heat conversion device, thereby improving the potential energy output and improving the system efficiency and economy.

[0080] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A multi-stage compressed air energy storage system for salt cavern gas storage, characterized in that: The invention comprises a salt cavern gas storage chamber (7), wherein the inlet end of the salt cavern gas storage chamber (7) is connected to a multi-stage compression device and a first heat exchanger (3), the outlet end of the salt cavern gas storage chamber (7) is connected to a multi-stage expansion power generation device and a second heat exchange device (6), the outlet end of the heat storage liquid of the first heat exchanger (3) is connected to the inlet end of the heat storage liquid of the first heat exchanger (3) via a high-temperature tank (8), a second heat exchange device (6) and a low-temperature tank (9); and the salt cavern gas storage chamber (7) and the high-temperature tank (8) are respectively connected to a pressure potential energy-heat energy coupling conversion device (10).

2. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 1 is characterized in that: The pressure potential energy-heat energy coupling conversion device (10) comprises a device housing (11), one end of the device housing (11) is provided with a converging top cover (16), and the other end is correspondingly provided with a diverting bottom cover (17), the converging top cover (16) is provided with a heat storage liquid outlet (14), and the diverting bottom cover (17) is provided with a heat storage liquid inlet (15); A high-pressure inlet (18) is provided on a side of the device housing (11) close to the converging top cover (16), and a low-pressure outlet (19) is provided on the other side of the device housing (11) close to the diverting bottom cover (17); A plurality of heat storage liquid pipelines (13) are arranged inside the device housing (11); one end of the plurality of heat storage liquid pipelines (13) is connected to the heat storage liquid outlet (14), and the other end is connected to the heat storage liquid inlet (15).

3. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 2 is characterized in that: An array of multiple heat storage liquid pipelines (13) is arranged in the device housing (11).

4. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 2 is characterized in that: Composite heat-releasing structures (12) are arranged at intervals on a plurality of heat-storage liquid pipelines (13).

5. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 4 is characterized in that: The composite heat-releasing structure (12) is arranged along the circumference of the device housing (11).

6. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 1, characterized in that: The multi-stage compression device comprises a first compression device (1) and a second compression device (2) which are connected in sequence, and a first heat exchanger (3) is arranged between the first compression device (1) and the second compression device (2).

7. The multi-stage compressed air energy storage system for salt cavern gas storage according to claim 1, characterized in that: The multi-stage expansion power generation device comprises a first expansion device (4) and a second expansion device (5) which are connected in sequence, and a second heat exchange device (6) is arranged between the first expansion device (4) and the second expansion device (5).

8. The control method of the multi-stage compressed air energy storage system for salt cavern gas storage according to any one of claims 1 to 7, characterized in that: include: The air is compressed by the multi-stage compressor and the first heat exchanger to recover excess heat, and then enters the salt cavern gas storage chamber under high pressure. The heat storage liquid absorbs the heat generated by the air compression through the first heat exchanger and is transferred from the low temperature tank to the high temperature tank; or The high-pressure gas in the salt cavern gas storage chamber absorbs heat and generates power through the multi-stage expansion device and the second heat exchange device. During this period, the energy storage liquid in the high-temperature tank transfers heat energy to the working air through the second heat exchange device and then flows back to the low-temperature tank for standby.

9. The control method of the multi-stage compressed air energy storage system for salt cavern gas storage according to claim 8, characterized in that: When there is sufficient gas in the salt cavern gas storage chamber, but the temperature of the energy storage liquid in the high-temperature tank does not meet the standard, the salt cavern gas storage chamber is connected to the pressure potential energy-thermal energy coupling conversion device to convert part of the air potential energy into thermal energy. At this time, the liquid in the high-temperature tank flows through the pressure potential energy-thermal energy coupling conversion device and then flows into the second heat exchange device.

10. The control method of the multi-stage compressed air energy storage system for salt cavern gas storage according to claim 8, characterized in that: When the system completes the energy release phase and enters the standby state for the next energy storage cycle, the valve is adjusted to connect the pressure potential energy-thermal energy coupling conversion device to the atmosphere to restore normal pressure.

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