A multi-energy synergistic S-CO2 energy storage system and method suitable for industrial parks

Abstract

This invention discloses a multi-energy synergistic S-CO2 energy storage system and method suitable for industrial parks, relating to the fields of supercritical carbon dioxide energy storage and comprehensive energy utilization in industrial parks. The system includes an energy storage, pressure stabilization, and temperature control subsystem; a compression heat storage subsystem; a multi-energy cascade heat replenishment subsystem; and an expansion work and regeneration subsystem. Through pressure stabilization and temperature regulation of the low-pressure working fluid followed by compression energy storage; primary heat replenishment during the energy release phase after compression heat storage; secondary heat replenishment using an S-CO2 heat pump unit to upgrade low-grade waste heat in the park; and preheating and tertiary heat replenishment using a main regenerator and a solar-powered molten salt heat storage unit, the working fluid enters the main expander unit to generate electricity. Through synergistic regulation, heat source fluctuations and temperature and pressure disturbances are suppressed, maintaining the working fluid in a supercritical stable operating state throughout the process. This invention enables efficient electrical energy storage and release, multi-grade heat energy cascade utilization, and coordinated operation of power supply and heating in the industrial park.

Description

Technical Field

[0001] This invention belongs to the field of supercritical carbon dioxide energy storage and integrated energy utilization technology in industrial parks. It relates to compressed energy storage, cascade heat replenishment, waste heat recovery and combined cooling, heating and power (CCHP). Specifically, it is a multi-energy synergistic supercritical carbon dioxide (S-CO2) energy storage system and method suitable for industrial parks. It is used to achieve efficient storage and release of electrical energy, synergistic utilization of multi-grade thermal energy and stable energy supply in industrial parks. It is especially suitable for multi-energy coupling energy supply scenarios in industrial parks. Background Technology

[0002] Industrial parks, as the core units of my country's energy consumption and carbon emissions, account for more than 65% of the country's total industrial energy consumption. They generally face core pain points such as difficulty in absorbing the volatility of high-proportion renewable energy, high pressure on grid peak-valley regulation, less than 10% resource utilization rate of low-grade waste heat (data center cooling waste heat, air conditioning condensation heat, etc.) at 50-70℃, and poor coordination of multi-energy systems of cooling, heating, electricity and gas. There is an urgent need to develop new energy storage technologies that are suitable for park scenarios, highly efficient, safe and multi-energy coordinated.

[0003] Supercritical carbon dioxide (S-CO2) energy storage technology, with its advantages such as mild critical parameters (critical temperature 31.1 ℃, critical pressure 7.38 MPa), high cycle efficiency, high volumetric energy density, lack of geographical limitations, and environmentally friendly inertness, has become a core technology for new energy storage in industrial parks. Existing S-CO2 energy storage technologies typically utilize CO2 in a supercritical state to complete the compression, storage, heating, and expansion processes, achieving the conversion between electrical and thermal energy. However, significant technical bottlenecks still exist. First, the compressor inlet operating conditions lack precise control methods, making it impossible to stably maintain the working fluid near the supercritical point, resulting in high compression power consumption that fluctuates significantly with varying operating conditions. Second, the system lacks a full-process pressure stabilization design, leading to significant pressure fluctuations during the charging and discharging of high and low pressure tanks, affecting the operational stability and rated efficiency of core equipment such as the compressor and expander. Third, the system operates mostly in independent modes, without deep coupling with the existing solar thermal molten salt system and low-grade waste heat resources in the industrial park, lacking a cascaded heat replenishment system architecture, thus limiting the improvement of cycle efficiency and overall energy utilization. Fourth, the system design lacks a strict thermodynamic and engineering constraint system, with some parameter designs violating basic heat transfer laws, resulting in insufficient engineering feasibility and long-term operational reliability. For example, unreasonable temperature difference organization at the hot and cold ends of the heat exchanger, insufficient connection between the heat replenishment and regeneration processes, and insufficient matching of the temperature ranges of the heat storage medium and the working fluid. These problems will all affect the thermodynamic perfection, engineering feasibility, and long-term operational reliability of the system.

[0004] To address the aforementioned issues, some explorations have been undertaken in this field. For example, Chinese patent CN121088594A discloses a solar and geothermal energy storage combined power generation system based on s-CO2, achieving long-term energy storage through geothermal reservoirs. However, this technology is highly dependent on geological conditions, and the unsteady heat exchange process between the working fluid and underground rock strata is highly uncertain, making it difficult to guarantee the precise stability of cycle parameters near the critical point. CN121229205A discloses a supercritical carbon dioxide energy storage system, which consists of a compressor, electric heater, high-temperature molten salt storage tank, and turbine forming a closed loop, and adjusts the electric heater power through feedback control. However, it mainly solves the heating power matching problem and lacks multi-energy collaborative drive, full-process voltage stabilization, and low-grade waste heat upgrading and access design. CN121088479A discloses a supercritical carbon dioxide energy storage and industrial waste energy coupling circulation system, which utilizes industrial coal gas waste heat and power plant condensate to achieve preheating, heating and cooling, and adopts two-stage expansion to do work. However, the working fluid needs to be condensed and liquefied back for storage, and it does not form a full-process supercritical operation and multi-temperature zone heat cascade synergistic utilization.

[0005] In summary, existing S-CO2 energy storage technologies still suffer from problems such as insufficient stability of compressor inlet operating conditions, significant pressure fluctuations during tank charging and discharging, inadequate utilization of heat of different grades, difficulty in efficiently integrating low-grade waste heat into the power cycle, and limited overall system energy utilization. Therefore, how to construct a supercritical carbon dioxide energy storage system that balances stable operation in the critical region of the working fluid, coordinated control of all operating conditions throughout the process, and efficient utilization of heat energy in multiple temperature zones is a pressing technical problem to be solved in this field. Summary of the Invention

[0006] (a) Purpose of the invention Based on the aforementioned defects and shortcomings of existing technologies, this invention proposes a multi-energy synergistic supercritical carbon dioxide (S-CO2) energy storage system and method suitable for industrial parks. By constructing a synergistic operation system that includes precise temperature control at the compressor inlet critical point, full-process pressure stabilization, compression heat storage and release, multi-energy cascade heat replenishment, full-process energy cascade utilization, expansion reheating, and end-point waste heat recovery, and by comprehensively designing the key pressure, temperature, and heat exchange matching relationships throughout the charging and discharging process, this invention achieves stable supercritical operation of the S-CO2 working fluid throughout the process, high-value utilization of low-grade waste heat, cascade utilization of multi-grade thermal energy in the park, and efficient synergy between energy storage power generation and heating load.

[0007] (II) Technical Solution To achieve the objective of this invention and solve its technical problems, the present invention adopts the following technical solution: The first objective of this invention is to provide a multi-energy synergistic S-CO2 energy storage system suitable for industrial parks. This system enables supercritical carbon dioxide energy storage, energy release for power generation, and combined heat and power supply under the synergistic effect of multiple energy sources, including grid peak shaving, industrial low-grade waste heat, and solar thermal energy. It includes at least an energy storage, voltage stabilization, and temperature control subsystem; an expansion and regeneration subsystem; a compression heat storage subsystem; and a multi-energy cascade heat replenishment subsystem, wherein: The energy storage, pressure stabilization, and temperature control subsystem includes at least a low-pressure S-CO2 storage tank, a main compressor unit, and a high-pressure S-CO2 storage tank connected in sequence by pipelines. Throttling and pressure stabilizing valves are installed at the exhaust ports of both the low-pressure and high-pressure S-CO2 storage tanks, and a temperature regulating heat exchanger is installed at the front end of the air inlet of the main compressor unit. The compression heat storage subsystem includes at least a heat storage heat exchanger, a heat release heat exchanger, a high-temperature hot water storage tank, and a low-temperature hot water storage tank. The hot side of the heat storage heat exchanger is connected to the exhaust pipe of the main compressor unit, the cold side of the heat release heat exchanger is connected to the exhaust pipe of the high-pressure S-CO2 storage tank, and the outlet of the low-temperature hot water storage tank is connected to the inlet of the high-temperature hot water storage tank through a pipeline via the cold side of the heat storage heat exchanger. The outlet of the high-temperature hot water storage tank is connected to the inlet of the low-temperature hot water storage tank through a pipeline via the hot side of the heat release heat exchanger. The multi-energy cascade heat replenishment subsystem includes an S-CO2 heat pump unit and a solar-powered polythermal molten salt heat storage unit. The S-CO2 heat pump unit is equipped with a heat pump compressor, a heat pump expander, a waste heat exchanger, a heat pump regenerator, and a heat pump heat exchanger. The cold side of the heat pump heat exchanger is connected to the exhaust pipe of the high-pressure S-CO2 storage tank and is located downstream of the hot side of the heat release heat exchanger. The exhaust port of the heat pump compressor is connected to the air inlet of the heat pump compressor after passing through the hot side of the heat pump heat exchanger, the hot side of the heat pump regenerator, the heat pump expander, the cold side of the waste heat exchanger, and the cold side of the heat pump regenerator in sequence. The solar-powered polythermal molten salt heat storage unit is equipped with a solar-powered module, a high-temperature molten salt storage tank, a low-temperature molten salt storage tank, and a molten salt heat exchanger. The cold side of the molten salt heat exchanger is connected to the exhaust pipe of the high-pressure S-CO2 storage tank. The outlet of the low-temperature molten salt storage tank is connected to the inlet of the high-temperature molten salt storage tank after passing through the solar-powered module. The outlet of the high-temperature molten salt storage tank is connected to the inlet of the low-temperature molten salt storage tank after passing through the hot side of the molten salt heat exchanger. The expansion and regeneration subsystem includes at least a main regenerator, a main expander and a generator set connected to it. The exhaust port of the high-pressure S-CO2 storage tank is connected to the inlet of the low-pressure S-CO2 storage tank via pipelines that pass sequentially through the cold side of the heat exchanger, the cold side of the heat pump heat exchanger, the cold side of the main regenerator, the cold side of the molten salt heat exchanger, the main expander and the hot side of the main regenerator.

[0008] The second objective of this invention is to provide a control method for a multi-energy synergistic S-CO2 energy storage system suitable for industrial parks, comprising at least the following steps: SS1. Operation status determination and mode switching: Collect grid load demand, renewable power output, working medium status of each S-CO2 storage tank and thermal storage status of each molten salt storage tank and hot water storage tank. When the grid is in a valley or renewable power is abundant, switch to energy storage mode. When the grid is in a peak or energy demand increases, switch to energy release mode. SS2. Energy storage, pressure stabilization, temperature control and compression energy storage: Under energy storage conditions, the working fluid discharged from the low-pressure S-CO2 storage tank is first stabilized by a throttling and pressure stabilizing valve, and then its temperature is adjusted by a temperature regulating heat exchanger. After the working fluid state is controlled near the critical point, it enters the main compressor unit. After releasing the heat of compression in the heat storage heat exchanger, it enters the high-pressure S-CO2 storage tank. SS3. Compression heat storage and primary heat replenishment: The compression heat recovered by the heat storage heat exchanger is stored in a high-temperature hot water storage tank; under the energy release condition, the working fluid discharged from the high-pressure S-CO2 storage tank is stabilized by the throttling and pressure regulating valve and then enters the heat release heat exchanger to exchange heat with the high-temperature hot water storage water to complete the primary heat replenishment. SS4. Low-grade waste heat upgrading and cascade supplementary heating: After the working fluid is first-stage supplemented heating, it enters the heat pump heat exchanger, the main regenerator and the molten salt heat exchanger in sequence. The low-grade waste heat in the park is upgraded by the S-CO2 heat pump unit and then supplemented for secondary heating. The waste heat of expansion exhaust is recovered by the main regenerator for preheating, and the solar thermal molten salt heat storage unit is used for tertiary heating. SS5. Expansion power generation and waste heat cogeneration: After the working fluid is heated in three stages, it enters the main expander unit to do work and drive the generator unit to generate electricity. After expansion, the working fluid is successively sent to the park heating or domestic hot water circuit through the terminal waste heat recovery heat exchanger to release heat and then returned to the low-pressure S-CO2 storage tank to complete the closed-loop circulation of the working fluid. The working fluid is kept in a supercritical state throughout the entire process of energy storage and release. SS6. Coordinated Regulation (Preferred Step): Based on the outlet temperature of the heat pump heat exchanger, the outlet temperature of the molten salt heat exchanger, the inlet temperature of the main expansion unit, the hot-side outlet temperature of the main regenerator, and the system load demand, adjust the opening of the bypass valves set on the corresponding bypass branches of the heat pump heat exchanger, the molten salt heat exchanger, and the main regenerator to allocate the S-CO2 working fluid flow ratio in each stage of heat replenishment and regeneration process, and suppress thermal shock, temperature over-limit, and pressure fluctuations caused by heat source fluctuations, operating condition switching, or low-load operation.

[0009] (III) Technical Effects Compared with the prior art, the multi-energy synergistic S-CO2 energy storage system and method of the present invention, applicable to industrial parks, has the following beneficial and significant technical effects: (1) This invention sets up a temperature-regulating heat exchanger before the compressor inlet, using low-cost air conditioning cooling water, waste heat recovery hot water or cooling water from the park as the medium, to achieve precise control of the working fluid inlet temperature near the critical pressure. Combined with the throttling and pressure-stabilizing valve at the outlet of the low-pressure storage tank, the working fluid at the compressor inlet operates stably in the range near the critical point. By utilizing the characteristic that the density near the critical point is close to that of a liquid, the compression power consumption is reduced. Compared with the conventional gas inlet compression system, the compression power consumption is reduced by more than 20%. At the same time, the working fluid is maintained in a supercritical state throughout the process, which completely avoids system oscillation, water hammer and equipment corrosion caused by two-phase flow conditions, and significantly improves the system operation stability and rated cycle efficiency.

[0010] (2) In view of the multi-energy characteristics of industrial parks, the present invention adopts a three-level cascade heat compensation architecture: the first-level heat compensation recovers the compression heat to realize the full energy closed-loop utilization of energy in the energy storage process; the second-level heat compensation uses S-CO2 high-temperature heat pump to make high-value utilization of the low-grade waste heat of 50~70℃ in the park, solving the problem that the low-grade waste heat of industry is difficult to be directly used for power cycle; the third-level heat compensation couples the existing solar thermal molten salt system in the park, and is also compatible with surplus renewable electricity electric heating compensation, raising the inlet temperature of the expander to above 450℃, greatly improving the cycle thermal efficiency, realizing the deep synergy of renewable energy, industrial waste heat and energy storage system, and constructing a zero-carbon park operation mode integrating source, grid, load and storage.

[0011] (3) This invention recovers high-temperature waste heat from the exhaust steam of the expander through a regenerator and realizes the resource utilization of low-temperature waste heat through a terminal waste heat recovery heat exchanger. It constructs a full-process energy cascade utilization system based on the principle of temperature matching and cascade utilization, which includes high-temperature work, medium-temperature heat recovery, and low-temperature heating. The system also has the multi-energy supply capability of power supply, heating and hot water supply, which perfectly meets the integrated needs of cooling, heating and electricity in zero-carbon parks. Compared with conventional independent S-CO2 energy storage systems, the overall energy efficiency is improved by more than 30%. At the same time, the thermodynamic and engineering constraint boundaries of all system equipment are established, and all parameters strictly follow the basic laws of thermodynamics and engineering design specifications, ensuring the engineering feasibility and long-term operational reliability of the system. Attached Figure Description

[0012] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood in conjunction with the following description of the embodiments, in which: Figure 1 The diagram shows a multi-energy synergistic supercritical carbon dioxide (S-CO2) energy storage system applicable to industrial parks according to the present invention. Figure 2 The diagram shows a control method flowchart for a multi-energy synergistic S-CO2 energy storage system applicable to industrial parks according to the present invention.

[0013] Explanation of reference numerals in the attached diagram: 1-Low-pressure S-CO2 storage tank, 2-Low-pressure storage tank outlet throttling and pressure-regulating valve, 3-Compressor inlet temperature regulating heat exchanger, 4-Main compressor unit, 5-Heat storage heat exchanger, 6-High-pressure S-CO2 storage tank, 7-High-pressure storage tank outlet throttling and pressure-regulating valve, 8-Heat release heat exchanger, 9-High-temperature hot water storage tank, 10-Low-temperature hot water storage tank, 11-Heat pump compressor, 12-Heat pump expander, 13-Waste heat exchanger, 14-Heat pump regenerator, 15-Heat pump heat exchanger, 16-Solar thermal module, 17-High-temperature molten salt storage tank, 18-Low-temperature molten salt storage tank, 19-Molten salt heat exchanger, 20-Main regenerator, 21-Main expander unit, 22-Terminal waste heat recovery heat exchanger, 23-First bypass valve, 24-Second bypass valve, 25-Third bypass valve. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. The described embodiments are some, but not all, embodiments of this invention, and are exemplary and intended to explain the invention, not to limit it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0015] Example 1: Multi-energy synergistic S-CO2 energy storage system like Figure 1 As shown in the embodiment of the present invention, a multi-energy synergistic supercritical carbon dioxide (S-CO2) energy storage system suitable for industrial parks is provided. This system is used to achieve supercritical carbon dioxide energy storage, energy release power generation, and waste heat co-supply under the synergistic drive of multiple energy sources in the park, including grid peak shaving, industrial low-grade waste heat, and solar thermal energy. Designed for the multi-energy co-supply needs of industrial parks, the system can achieve synergistic coupling and cascade utilization of electrical energy, compression heat, low-grade waste heat, and solar thermal energy under operating conditions of renewable energy fluctuations, significant grid peak-valley differences, and continuous park heat load. The entire system adopts a counter-current heat exchange architecture, and all equipment parameters strictly follow thermodynamic laws and engineering design specifications. The core system consists of subsystems such as an energy storage, pressure stabilization, and temperature control subsystem, an expansion work and regeneration subsystem, a compression heat storage subsystem, and a multi-energy cascade heat replenishment subsystem. Under a unified control strategy, each subsystem achieves supercritical stable operation of the working fluid throughout the entire process and cascade utilization of multi-grade thermal energy. Specifically: The energy storage, pressure stabilization, and temperature control subsystem comprises, sequentially connected via gas pipelines, a low-pressure S-CO2 storage tank 1, a low-pressure storage tank outlet throttling and pressure-stabilizing valve 2, a compressor inlet temperature regulating heat exchanger 3, a main compressor unit 4 (preferably a multi-stage centrifugal compressor), a high-pressure S-CO2 storage tank 6, and a high-pressure storage tank outlet throttling and pressure-stabilizing valve 7. The temperature regulating heat exchanger 3 uses park air conditioning cooling water or waste heat recovery hot water as the regulating medium, precisely adjusting the compressor inlet working fluid temperature to maintain it stably near the critical point, thereby reducing compressor power consumption. The throttling and pressure-stabilizing valves 2 and 7 at the outlets of the high- and low-pressure S-CO2 storage tanks 1 and 6 enable precise and stable control of the working fluid outlet pressure during charging and discharging, eliminating the impact of tank pressure fluctuations on system operation.

[0016] Preferably, both high-pressure and low-pressure S-CO2 storage tanks 1 and 6 are equipped with pressure and temperature sensors. Each throttling and pressure-regulating valve 2 and 7 is an electrically adjustable valve with continuously adjustable opening, communicating with the controller. This dynamically adjusts the exhaust flow and pressure based on the internal pressure and temperature of the tanks, ensuring stable intake pressure boundary conditions at the main compressor unit 4 during energy storage operations, stable inlet pressure boundary conditions in the subsequent energy release branch of the high-pressure S-CO2 storage tank, and suppressing pressure fluctuations, temperature drift, and flow pulsations during the tank exhaust process. In actual engineering implementation, each pressure sensor, temperature sensor, and electrically adjustable valve can be connected to a unified control unit. The control unit performs closed-loop regulation of the opening of each throttling and pressure-regulating valve 2 and 7 based on preset pressure control targets, temperature control targets, and allowable fluctuation ranges. If necessary, flow sensors can be further configured on the inlet and outlet pipelines of the storage tanks to improve the accuracy of identifying the tank's exhaust conditions and the response speed of the pressure regulation control.

[0017] In addition, the compressor inlet temperature regulating heat exchanger 3 is preferably a dual-channel counter-flow heat exchanger, with its cold side connected to the compressor unit's intake pipe and its hot side connected to a low-temperature water circuit. The low-temperature water circuit uses park air conditioning cooling water and / or waste heat recovery hot water as the temperature regulating medium. The S-CO2 working fluid discharged from the low-pressure S-CO2 storage tank 1 is first controlled by the throttling and pressure regulating valve 2 for pressure stabilization, and then enters the temperature regulating heat exchanger 3 for heat exchange and temperature regulation, so that the temperature of the S-CO2 working fluid entering the main compressor unit 4 is maintained at 32.5~38 ℃ and the pressure is maintained at 7.6~8.5 MPa in the supercritical critical point range, thereby utilizing the high density and low specific volume thermal properties of the working fluid near the critical region to reduce compression power consumption.

[0018] Furthermore, the main compressor unit 4 is preferably a multi-stage centrifugal compressor with a pressure ratio controlled between 2.6 and 3.9. After pressure stabilization and temperature control, the S-CO2 working fluid enters the main compressor unit 4 and is pressurized to 20-30 MPa. The temperature of the working fluid after compression is controlled between 100-150 ℃. After being cooled by the heat storage heat exchanger 5, the high-temperature and high-pressure S-CO2 working fluid enters the high-pressure S-CO2 storage tank 6 at a temperature of 45-50 ℃ and a pressure of 19.8-29.7 MPa to complete energy storage. The temperature of the working fluid in the high-pressure S-CO2 storage tank 6 is always maintained above the critical temperature to avoid entering a two-phase flow operation state.

[0019] The compression heat storage subsystem includes a heat storage heat exchanger 5, a heat release heat exchanger 8, a high-temperature hot water storage tank 9, and a low-temperature hot water storage tank 10. The hot side of the heat storage heat exchanger 5 is connected to the exhaust pipe of the main compressor unit 4, and the cold side of the heat release heat exchanger 8 is connected to the exhaust pipe of the high-pressure S-CO2 storage tank 6. The outlet of the low-temperature hot water storage tank 10 is connected to the high-temperature hot water storage tank 9 via the cold side of the heat storage heat exchanger 5, and the outlet of the high-temperature hot water storage tank 9 is connected to the inlet of the low-temperature hot water storage tank 10 via the hot side of the heat release heat exchanger 8. This enables efficient storage of compression heat during the energy storage phase and precise release of compression heat during the energy release phase.

[0020] Preferably, both the heat storage heat exchanger 5 and the heat release heat exchanger 8 are counter-flow heat exchangers, and both the high-temperature hot water storage tank 9 and the low-temperature hot water storage tank 10 are pressurized closed hot water storage tanks (e.g., 1MPa pressurized closed hot water storage tanks). Under energy storage conditions, the high-temperature and high-pressure S-CO2 working fluid discharged from the main compressor unit 4 exchanges heat with the low-temperature hot water storage water in a counter-flow manner through the heat storage heat exchanger 5, storing the heat generated during the compression process in the high-temperature hot water storage tank 9. Under energy release conditions, the working fluid discharged from the high-pressure S-CO2 storage tank 6 first enters the heat release heat exchanger 8, exchanges heat with the high-temperature pressurized hot water storage water discharged from the high-temperature hot water storage tank 9 in a counter-flow manner, and completes the first-stage heat replenishment in the energy release stage. After the high-temperature hot water storage water releases heat, it flows back to the low-temperature hot water storage tank 10, forming a closed compression heat storage and release loop.

[0021] Multi-energy cascade heat replenishment subsystem: includes S-CO2 heat pump unit and solar thermal molten salt storage unit. The S-CO2 heat pump unit is equipped with heat pump compressor 11, heat pump expander 12, waste heat exchanger 13, heat pump regenerator 14, and heat pump heat exchanger 15. The cold side of heat pump heat exchanger 15 is connected to the exhaust pipe of high-pressure S-CO2 storage tank 6 and is located downstream of heat release heat exchanger 8. The exhaust port of heat pump compressor 11 is connected to the inlet of heat pump compressor 11 after passing through the hot side of heat pump heat exchanger 15, the hot side of heat pump regenerator 14, heat pump expander 12, the cold side of waste heat exchanger 13, and the cold side of heat pump regenerator 14, thus forming a closed loop on the heat pump side. The solar thermal molten salt storage unit is equipped with a solar thermal module 16, a high-temperature molten salt storage tank 17, a low-temperature molten salt storage tank 18, and a molten salt heat exchanger 19. The cold side of the molten salt heat exchanger 19 is connected to the exhaust pipe of the high-pressure S-CO2 storage tank 6 and is located downstream of the cold side of the main regenerator 20. The outlet of the low-temperature molten salt storage tank 18 is connected to the inlet of the high-temperature molten salt storage tank 17 after passing through the solar thermal module 16. The outlet of the high-temperature molten salt storage tank 17 is connected to the inlet of the low-temperature molten salt storage tank 18 after passing through the hot side of the molten salt heat exchanger 19, thus forming a closed molten salt circulation loop.

[0022] Preferably, in the S-CO2 heat pump unit, the hot side of the waste heat exchanger 13 is connected to the waste heat loop of the park, using the 50~70℃ condensing heat of the park's air conditioning and the waste heat from the data center as low-temperature heat sources. The heat pump compressor 11, heat pump heat exchanger 15, heat pump regenerator 14, heat pump expander 12, and waste heat exchanger 13 are connected by pipelines to form a closed loop. The S-CO2 working fluid is compressed by the heat pump compressor 11 and enters the heat pump heat exchanger 15 to release heat. After expanding, cooling, and depressurizing by the heat pump expander 12, it enters the waste heat exchanger 13 to absorb low-grade waste heat. Then, it undergoes heat regeneration and heat exchange with the compressed high-temperature S-CO2 working fluid in the heat pump regenerator 14 before returning to the heat pump compressor 11. The whole unit constitutes a regenerative reverse Brayton cycle with a rated operating performance coefficient of 2.5~3.5. The heat pump unit's heating outlet temperature can reach 150~200℃. Correspondingly, the heat pump heat exchanger 15 can further heat the S-CO2 working fluid after the first stage of supplementary heating to 150~200 ℃, realizing the second stage of supplementary heating of the S-CO2 working fluid in the energy release stage.

[0023] Preferably, in the solar thermal molten salt storage unit, the solar thermal module 16 can adopt a 500℃-level tower-type heliostat concentrating heat collection structure. A closed molten salt circulation loop is formed between the high-temperature molten salt storage tank 17 and the low-temperature molten salt storage tank 18. After the low-temperature molten salt working fluid is heated by the solar thermal module 16, it enters the high-temperature molten salt storage tank 17 for storage. During the energy release stage, it is further heated by the molten salt heat exchanger 19 to the S-CO2 working fluid, which has been preheated by the main regenerator 20, to above 450℃, realizing the three-stage heat replenishment of the S-CO2 working fluid. The molten salt temperature at the outlet of the molten salt heat exchanger 19 is controlled above the molten salt freezing point. In addition, the solar thermal molten salt storage unit can also pre-replenish the molten salt loop with heat through the electric heating modules installed in the high-temperature molten salt storage tank 17 and / or the low-temperature molten salt storage tank 18 during periods of sufficient renewable electricity, realizing the cross-time consumption of renewable energy.

[0024] The expansion and regeneration subsystem includes the main regenerator 20, the main expander (preferably a multi-stage axial flow expander), and a generator set mechanically connected to it. The exhaust port of the high-pressure S-CO2 storage tank 6 is connected to the inlet of the low-pressure S-CO2 storage tank 1 via pipelines through the cold side of the heat exchanger 8, the cold side of the heat pump heat exchanger 15, the cold side of the main regenerator 20, the cold side of the molten salt heat exchanger 19, the main expander 21, and the hot side of the main regenerator 20. This forms the first-stage heat replenishment, second-stage heat replenishment, third-stage heat replenishment, expansion and regeneration process in the main energy storage and release loop, realizing the efficient conversion of working fluid thermal energy and pressure potential energy into electrical energy, while recovering the medium and high temperature waste heat of the expander exhaust.

[0025] Preferably, the main regenerator 20 is a high-efficiency plate regenerator. After the secondary heat treatment, the S-CO2 working fluid enters the cold side of the main regenerator 20 and exchanges heat countercurrently with the high-temperature working fluid discharged from the expander unit 21 on the hot side of the main regenerator 20 to recover the medium and high temperature waste heat in the expansion exhaust. This raises the temperature of the S-CO2 working fluid to 300~400 ℃ before it enters the molten salt heat exchanger 19. The main expander unit 21 is preferably a multi-stage axial flow expander with an inlet working fluid temperature of over 450 ℃. Its expansion ratio is matched with the pressure ratio of the main compressor unit. The outlet pressure of the expanded working fluid is controlled at 7.8~8.7 MPa, and it drives the generator set connected to it to generate electricity, realizing the conversion of the working fluid's thermal energy and pressure potential energy into electrical energy.

[0026] In addition, the system also includes a counter-current waste heat recovery heat exchanger 22 located between the hot-side outlet of the main regenerator 20 and the inlet of the low-pressure S-CO2 storage tank 1. Its hot side is connected to a 0.1MPa atmospheric pressure water circuit, which is used to convert the residual low-temperature waste heat after expansion work and main regeneration into loads such as winter heating and domestic hot water for bathing in the park, realizing the cascade utilization of energy throughout the process. The S-CO2 working fluid after terminal waste heat recovery is returned to the low-pressure S-CO2 storage tank 1 in a supercritical state of 33-39 ℃ and 7.7-8.6 MPa.

[0027] In a further preferred embodiment, a first bypass branch with a bypass valve 23 is connected in parallel between the inlet and outlet of the cold side channel of the heat pump heat exchanger 15; a second bypass branch with a bypass valve 24 is connected in parallel between the inlet and outlet of the hot side channel of the main regenerator 20; and a third bypass branch with a bypass valve 25 is connected in parallel between the inlet and outlet of the cold side channel of the molten salt heat exchanger 19. Each bypass branch is used to bypass and regulate the working fluid flow of the corresponding heat exchanger when the corresponding heat exchanger is started, operating at low load, switching operating conditions, or when the temperature exceeds the limit, so as to regulate the temperature difference on both sides of the corresponding heat exchanger, control the outlet temperature and pressure of the working fluid, and suppress heat source fluctuations, load changes, or operating condition thermal shock and flow resistance fluctuations.

[0028] The multi-energy synergistic S-CO2 energy storage system suitable for industrial parks provided in this embodiment of the invention has the following working principle, workflow, and key design parameters: Under energy storage conditions (valley grid / peak renewable energy generation periods), the working fluid in the low-pressure S-CO2 storage tank 1 first achieves stable pressure control through the tank outlet throttling and pressure regulating valve 2, and then enters the compressor inlet temperature regulating heat exchanger 3. The working fluid temperature is precisely regulated by air conditioning cooling water or waste heat recovery hot water, so that it is stably maintained in the supercritical critical point range of 32.5~38 ℃ and 7.6~8.5 MPa. By utilizing the high density and low specific volume thermophysical characteristics of the working fluid near the critical point, the compression power consumption is significantly reduced from the source.

[0029] After pressure and temperature stabilization, the working fluid enters a multi-stage centrifugal compressor to complete the pressurization process. The outlet working fluid pressure is controlled at 20~30 MPa, with a pressure ratio of 2.6~3.9, and the temperature of the working fluid after compression can reach 100~150 ℃. The high-temperature and high-pressure S-CO2 after pressurization enters the heat storage heat exchanger 5, where it exchanges heat countercurrently with 1MPa pressurized cooling water, efficiently storing the heat of compression in the heat storage medium. After being cooled by the heat storage heat exchanger 5, the temperature of the S-CO2 working fluid drops to 45~50 ℃, and the pressure is maintained at 19.8~29.7 MPa. It then enters the high-pressure S-CO2 storage tank 6 to complete the energy storage process. The temperature of the working fluid inside the tank is always maintained above the critical temperature, avoiding two-phase flow conditions throughout the process. A throttling and pressure-stabilizing valve 7 is installed at the outlet of the high-pressure storage tank to provide a stable inlet pressure condition for the discharge stage.

[0030] Under energy release conditions (peak grid periods / renewable energy shortage periods), the working fluid in the high-pressure S-CO2 storage tank 6, after its pressure is stabilized by the outlet throttling and pressure regulating valve 7, enters the heat exchanger 8 to exchange heat countercurrently with the high-temperature stored hot water of the thermal storage subsystem, recovering the compression heat stored during the energy storage stage. The working fluid that has completed the first-stage heat replenishment enters the heat pump heat exchanger 15 to exchange heat countercurrently with the high-temperature working fluid of the S-CO2 heat pump unit, achieving the second-stage heat replenishment. The S-CO2 heat pump unit uses the low-grade waste heat of 50~70 ℃ in the park as a low-temperature heat source, and improves the waste heat grade through a regenerative reverse Brayton cycle. Its rated operating performance coefficient is 2.5~3.5, and the heating temperature can reach 150~200 ℃.

[0031] After secondary reheating, the S-CO2 working fluid enters the main regenerator 20, where it exchanges heat counter-currently with the high-temperature exhaust steam from the outlet of the main expander unit 21, recovering medium- and high-temperature waste heat for preheating. After heat exchange, the working fluid temperature rises to 300~400 ℃. Subsequently, the S-CO2 working fluid enters the molten salt heat exchanger 19, where it exchanges heat counter-currently with the solar-heated molten salt in the park to achieve final temperature increase. The molten salt outlet temperature is strictly controlled above its freezing point. After heat exchange, the working fluid temperature can reach above 450 ℃, meeting the rated inlet temperature requirements of the expander.

[0032] High-temperature, high-pressure S-CO2 working fluid undergoes adiabatic expansion in a multi-stage axial-flow expander, driving a synchronous generator to produce electricity. Its expansion ratio is precisely matched to the pressure ratio of the main compressor unit, with the outlet pressure controlled at 7.8~8.7 MPa. The high-temperature exhaust steam from the main expander unit outlet enters the hot side of the main regenerator 20 to release waste heat, then enters the terminal waste heat recovery heat exchanger 22, where it exchanges heat counter-currently with atmospheric pressure water at 0.1 MPa to recover remaining waste heat for domestic hot water production. The inlet temperature of the atmospheric pressure water is either ambient temperature or the heating cycle temperature. After being cooled by waste heat recovery, the S-CO2 working fluid maintains a supercritical state at a temperature of 33~39 ℃ and a pressure of 7.7~8.6 MPa before entering the S-CO2 low-pressure storage tank 1, completing a full charge-discharge cycle. It operates stably within the load range, adapting to the dynamic changes in renewable energy fluctuations and multi-energy loads in the industrial park.

[0033] The main power source of this invention's system is the expander's power generation, while the power consumption comes from the compressor and the carbon dioxide heat pump. The electro-electric efficiency is greater than 90%, primarily due to the improvement of low-grade heat sources by the high-temperature carbon dioxide heat pump and the enhancement of energy storage system performance by solar molten salt supplementation. Considering that the efficiency of waste heat recovery and molten salt heating is above 75%, the electro-electric efficiency of compressed gas energy storage is generally below 70%, and the highest efficiency of gas-liquid energy storage is generally no more than 75%, far lower than the system of this invention. This demonstrates the significant advantage of this system in leveraging the cascaded heat utilization of industrial parks. Furthermore, existing carbon dioxide energy storage systems often employ a gas-liquid energy storage method. Due to the large area occupied by the gas form, this scheme, while highly efficient, has low energy density. This invention not only has extremely high efficiency but also very high energy density, reducing the footprint by more than 50% compared to traditional gas-liquid energy storage methods, making it more suitable for integrated deployment in industrial park scenarios.

[0034] Example 2: Control method for multi-energy synergistic S-CO2 energy storage system Based on Embodiment 1 above, Embodiment 2 further provides a control method for the aforementioned multi-energy synergistic S-CO2 energy storage system applicable to industrial parks. This control method is designed for scenarios involving grid peak shaving, low-grade waste heat utilization, solar thermal utilization, and coordinated heating load in industrial parks. The controller provides unified and coordinated control of the energy storage voltage and temperature control subsystem, the compression heat storage subsystem, the multi-energy cascade heat replenishment subsystem, and the expansion work and regeneration subsystem. This achieves orderly switching between energy storage and energy release conditions and ensures that the S-CO2 working fluid maintains supercritical stable operation throughout the entire process. Specifically, as follows... Figure 2 As shown, the control method mainly includes the following steps during implementation: SS1. Operation Status Determination and Mode Switching: Collect data on grid load demand, renewable power output, working medium status of each S-CO2 storage tank, and thermal storage status of each molten salt storage tank and hot water storage tank. Switch to energy storage mode during grid off-peak periods or when renewable power is abundant, and switch to energy release mode during grid peak periods or when energy demand increases.

[0035] As a preferred option, the operation status determination and mode switching include: real-time acquisition of pressure and temperature parameters of the working fluid in the low-pressure S-CO2 storage tank 1 and the high-pressure S-CO2 storage tank 6; acquisition of the thermal storage status of the high-temperature hot water storage tank 9 and the high-temperature molten salt storage tank 17; acquisition of grid load demand parameters and renewable power output parameters; when neither the high-pressure S-CO2 storage tank 6 nor the high-temperature hot water storage tank 9 has reached the preset upper limit, and the grid is in a low-load state or a state of surplus renewable power, the control system switches to the energy storage mode; when the high-pressure S-CO2 storage tank 6 and the high-temperature molten salt storage tank 17 meet the preset energy release conditions, and the grid is in a peak load state or a state of increased electricity and heating demand in the park, the control system switches to the energy release mode.

[0036] SS2. Energy Storage, Pressure Stabilization, Temperature Control, and Compression Energy Storage: Under energy storage conditions, the S-CO2 working fluid discharged from the low-pressure S-CO2 storage tank 1 is first stabilized by the low-pressure storage tank outlet throttling and pressure stabilizing valve 2, and then its temperature is adjusted by the compressor inlet temperature regulating heat exchanger 3, so that the S-CO2 working fluid entering the main compressor unit 4 is maintained in the range near the critical point; then the main compressor unit 4 is controlled to pressurize the working fluid, and the pressurized working fluid releases the heat of compression through the heat storage heat exchanger 5 before entering the high-pressure S-CO2 storage tank 6 to complete energy storage.

[0037] Preferably, step SS2 includes: controlling the opening of the low-pressure storage tank outlet throttling and pressure-regulating valve 2 to maintain the inlet pressure of the main compressor unit 4 at 7.6–8.5 MPa; controlling the compressor inlet temperature to regulate the heat exchange intensity between the heat exchanger 3 and the low-temperature water circuit, so that the temperature of the S-CO2 working fluid entering the main compressor unit 4 is maintained at 32.5–38 °C; controlling the operation of the main compressor unit 4 under the above temperature and pressure conditions, so that the S-CO2 working fluid is compressed to 20–30 MPa, and the temperature of the working fluid after compression is controlled at 100–150 °C; further controlling the compressed S-CO2 working fluid to enter the heat storage heat exchanger 5, and after countercurrent heat exchange with the pressurized cooling water, it enters the high-pressure S-CO2 storage tank 6 at a temperature of 45–50 °C and a pressure of 19.8–29.7 MPa, and maintaining the working fluid temperature in the high-pressure S-CO2 storage tank 6 always above the critical temperature.

[0038] SS3. Compression Heat Storage and Primary Heat Replenishment: Under energy storage conditions, the compression heat recovered by the heat storage heat exchanger 5 is stored in the high-temperature hot water storage tank 9; under energy release conditions, the S-CO2 working fluid discharged from the high-pressure S-CO2 storage tank 6 is controlled to enter the heat release heat exchanger 8 after being regulated by the high-pressure storage tank outlet throttling and pressure regulating valve 7, and exchanges heat with the pressurized hot water discharged from the high-temperature hot water storage tank 9 to complete the primary heat replenishment in the energy release stage.

[0039] Preferably, the compression heat storage and primary heat replenishment include: under energy storage conditions, controlling the pressurized hot water in the low-temperature hot water storage tank 10 to enter the cold side of the heat storage heat exchanger 5, where it exchanges heat countercurrently with the high-temperature and high-pressure S-CO2 working fluid discharged from the main compressor unit 4, and then introducing the heated hot water into the high-temperature hot water storage tank 9 for storage; under energy release conditions, controlling the S-CO2 working fluid discharged from the high-pressure S-CO2 storage tank 6 to first enter the cold side of the heat release heat exchanger 8, while simultaneously controlling the pressurized hot water in the high-temperature hot water storage tank 9 to enter the hot side of the heat release heat exchanger 8, releasing the compression heat to the S-CO2 working fluid through countercurrent heat exchange, achieving primary heat replenishment, and then returning the heated hot water to the low-temperature hot water storage tank 10.

[0040] SS4. Low-grade waste heat upgrading and staged supplementary heating: After primary supplementary heating, the S-CO2 working fluid sequentially enters the heat pump heat exchanger 15, the main regenerator 20, and the molten salt heat exchanger 19. The S-CO2 heat pump unit upgrades the low-grade waste heat in the park and then performs secondary supplementary heating on the S-CO2 working fluid. The main regenerator 20 recovers the medium- and high-temperature waste heat from the exhaust steam of the main expansion unit 21 to preheat the S-CO2 working fluid. The solar thermal molten salt heat storage unit is used to perform terminal temperature enhancement on the S-CO2 working fluid, so that the temperature of the S-CO2 working fluid entering the main expansion unit 21 reaches above 450 ℃.

[0041] As a preferred option, the low-grade waste heat upgrading and secondary supplementary heating includes: controlling the waste heat exchanger 13 in the S-CO2 heat pump unit to absorb heat from the 50-70 ℃ low-grade waste heat loop in the park, and making the heat pump compressor 11, heat pump heat exchanger 15, heat pump regenerator 14, heat pump expander 12 and waste heat exchanger 13 form a regenerative reverse Brayton cycle; and further heating the S-CO2 working fluid after the primary supplementary heating to 150-200 ℃ through the heat pump heat exchanger 15 to complete the secondary supplementary heating in the energy release stage. Subsequently, the working fluid after secondary reheating is controlled to enter the cold side of the main regenerator 20, where it exchanges heat countercurrently with the high-temperature S-CO2 working fluid discharged from the main expander unit 21 on the hot side of the main regenerator 20, raising the working fluid temperature to 300-400 ℃. Then, the S-CO2 working fluid is controlled to enter the molten salt heat exchanger 19, where it exchanges heat with the high-temperature molten salt output from the solar thermal molten salt storage unit, so that the working fluid temperature before entering the main expander unit 21 reaches above 450 ℃, and the molten salt temperature at the outlet of the molten salt heat exchanger 19 is controlled to be maintained above the molten salt freezing point.

[0042] SS5. Expansion Power Generation and Waste Heat Cogeneration: The S-CO2 working fluid after three-stage reheating enters the main expander unit 21 to do work and drive the generator unit to generate electricity; the expanded S-CO2 working fluid releases heat through the main regenerator 20 and the terminal waste heat recovery heat exchanger 22 in sequence, and after releasing heat to the park heating circuit and / or domestic hot water circuit, it returns to the low-pressure S-CO2 storage tank 1 to complete the closed-loop circulation of the working fluid, and keeps the working fluid in a supercritical state throughout the entire process of energy storage and release.

[0043] Preferably, the expansion power generation and waste heat cogeneration includes: controlling the main expander unit 21 to operate at an expansion ratio that matches the pressure ratio of the main compressor unit 4, so that the outlet pressure of the main expander unit 21 is controlled at 7.8-8.7 MPa; controlling the high-temperature working fluid discharged from the main expander unit 21 to first enter the hot side of the main regenerator 20 to release medium-high temperature waste heat, and then enter the hot side of the terminal waste heat recovery heat exchanger 22 to exchange heat countercurrently with the 0.1 MPa atmospheric pressure water circuit to output heating heat for park heating and / or domestic hot water heat; the working fluid after terminal waste heat recovery is returned to the low-pressure S-CO2 storage tank 1 at 33-39 ℃ and 7.7-8.6 MPa.

[0044] SS6. Coordinated Regulation: Based on the outlet temperature of heat pump heat exchanger 15, the outlet temperature of molten salt heat exchanger 19, the inlet temperature of main expansion unit 21, the hot-side outlet temperature of main regenerator 20, and the system load demand, the opening degree of the bypass valves set on the corresponding bypass branches of heat pump heat exchanger 15, main regenerator 20, and molten salt heat exchanger 19 is adjusted to allocate the S-CO2 working fluid flow ratio in each stage of heat replenishment and regeneration process, so as to suppress thermal shock, temperature over-limit and pressure fluctuation caused by heat source fluctuation, operating condition switching or low load operation.

[0045] Preferably, step SS6 includes: setting up a first bypass branch between the inlet and outlet of the cold side channel of the heat pump heat exchanger 15, and adjusting the flow rate ratio of the S-CO2 working fluid flowing through the heat pump heat exchanger 15 through the first bypass valve 23; setting up a second bypass branch between the inlet and outlet of the hot side channel of the main regenerator 20, and adjusting the flow rate ratio of the working fluid on the hot side of the main regenerator 20 through the second bypass valve 24; and setting up a third bypass branch between the inlet and outlet of the cold side channel of the molten salt heat exchanger 19, and adjusting the flow rate ratio of the S-CO2 working fluid flowing through the molten salt heat exchanger 19 through the third bypass valve 25. The controller coordinates the opening of the first bypass valve 23, the second bypass valve 24, and the third bypass valve 25 based on the outlet temperature of the heat pump heat exchanger 15, the outlet temperature of the molten salt heat exchanger 19, the inlet temperature of the main expansion unit 21, the hot side outlet temperature of the main regenerator 20, and the system load demand. This enables dynamic flow redistribution to each stage of the heat exchange process when the corresponding heat exchanger starts up, operates at low load, switches operating conditions, or exceeds the temperature limit.

[0046] The control method described in Example 2, through the above steps, enables a smooth switching between energy storage and energy release modes, and allows all aspects of the system—energy storage voltage and temperature stabilization, compression heat recovery, low-grade waste heat upgrading, main regenerative preheating, molten salt terminal temperature enhancement, expansion power generation, and end-point waste heat co-generation—to operate collaboratively under a unified control logic. This not only improves the load adaptability and operational stability of the S-CO2 energy storage system in industrial park scenarios, but also helps to enhance energy storage and release efficiency, multi-grade heat energy utilization efficiency, and the overall energy supply capacity of the park.

[0047] The objectives of this invention have been fully and effectively achieved through the above embodiments. Those skilled in the art will understand that this invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments described above. Although the invention has been described with reference to what is currently considered the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, and any modifications that do not depart from the functional and structural principles of the invention will be included within the scope of the claims.

Claims

1. A multi-energy synergistic S-CO2 energy storage system suitable for industrial parks, characterized in that, At least including: The energy storage, pressure stabilization, and temperature control subsystem includes a low-pressure S-CO2 storage tank, a main compressor unit, and a high-pressure S-CO2 storage tank connected in sequence. Throttling and pressure stabilizing valves are installed at the exhaust ports of both the low-pressure and high-pressure S-CO2 storage tanks, and a temperature regulating heat exchanger is installed at the front end of the air inlet of the main compressor unit. The compression heat storage subsystem includes a heat storage heat exchanger, a heat release heat exchanger, a high-temperature hot water storage tank, and a low-temperature hot water storage tank. The hot side of the heat storage heat exchanger is connected to the exhaust pipeline of the main compressor unit, and the cold side of the heat release heat exchanger is connected to the exhaust pipeline of the high-pressure S-CO2 storage tank. The outlet of the low-temperature hot water storage tank is connected to the high-temperature hot water storage tank through the cold side of the heat storage heat exchanger, and the outlet of the high-temperature hot water storage tank is connected to the low-temperature hot water storage tank through the hot side of the heat release heat exchanger. The multi-energy cascade heat replenishment subsystem includes an S-CO2 heat pump unit and a solar polythermal molten salt thermal storage unit. The S-CO2 heat pump unit comprises a heat pump compressor, a heat pump expander, a waste heat exchanger, a heat pump regenerator, and a heat pump heat exchanger. The cold side of the heat pump heat exchanger is connected to the exhaust pipe of the high-pressure S-CO2 storage tank and is located downstream of the heat release heat exchanger. The exhaust port of the heat pump compressor sequentially passes through the hot side of the heat pump heat exchanger, the hot side of the heat pump regenerator, the heat pump expander, and the cold side of the waste heat exchanger. The cold side of the heat pump regenerator is connected to the air inlet of the heat pump compressor; the solar thermal molten salt storage unit is equipped with a solar thermal module, a high-temperature molten salt storage tank, a low-temperature molten salt storage tank, and a molten salt heat exchanger. The cold side of the molten salt heat exchanger is connected to the exhaust pipe of the high-pressure S-CO2 storage tank and is located downstream of the cold side of the main regenerator. The outlet of the low-temperature molten salt storage tank is connected to the high-temperature molten salt storage tank after passing through the solar thermal module. The outlet of the high-temperature molten salt storage tank is connected to the low-temperature molten salt storage tank after passing through the hot side of the molten salt heat exchanger. The expansion and regeneration subsystem includes the main regenerator, the main expander and the generator set connected to it. The exhaust port of the high-pressure S-CO2 storage tank is connected to the inlet of the low-pressure S-CO2 storage tank through pipelines in sequence through the cold side of the heat exchanger, the cold side of the heat pump heat exchanger, the cold side of the main regenerator, the cold side of the molten salt heat exchanger, the main expander and the hot side of the main regenerator.

2. The system according to claim 1, characterized in that, In the energy storage pressure stabilization and temperature control subsystem, each S-CO2 storage tank is equipped with a pressure sensor and a temperature sensor. Each throttling and pressure regulating valve is an electric regulating valve that is connected to the controller and has a continuously adjustable opening. It is used to dynamically adjust the exhaust flow and exhaust pressure of the storage tank according to the internal pressure and temperature of the storage tank, so that the intake port of the main compressor unit forms a stable intake pressure boundary condition under energy storage conditions, the subsequent energy release branch of the high-pressure S-CO2 storage tank forms a stable inlet pressure boundary condition, and suppresses pressure fluctuations, temperature drift and flow pulsation during the exhaust process of the storage tank.

3. The system according to claim 2, characterized in that, In the energy storage, pressure stabilization, and temperature control subsystem, the temperature regulating heat exchanger at the main compressor unit inlet is a dual-channel counter-flow heat exchanger. Its cold side is connected to the compressor unit inlet pipeline, and its hot side is connected to the low-temperature water circuit. The low-temperature water circuit uses park air conditioning cooling water and / or waste heat recovery hot water as the temperature regulating medium. The S-CO2 working fluid discharged from the low-pressure S-CO2 storage tank is first controlled by a throttling and pressure regulating valve for pressure stabilization, and then enters the temperature regulating heat exchanger for heat exchange and temperature regulation, so that the temperature of the S-CO2 working fluid entering the main compressor unit is maintained at 32.5~38 ℃ and the pressure is maintained at 7.6~8.5 MPa in the supercritical critical point range.

4. The system according to claim 3, characterized in that, The main compressor unit is a multi-stage centrifugal compressor with a pressure ratio of 2.6~3.

9. After pressure stabilization and temperature control, the S-CO2 working fluid enters the main compressor unit and is pressurized to 20~30 MPa. The working fluid temperature after compression is controlled at 100~150 ℃. After being cooled by a heat storage heat exchanger, it enters the high-pressure S-CO2 storage tank at a temperature of 45~50 ℃ and a pressure of 19.8~29.7 MPa to complete energy storage. The working fluid temperature in the high-pressure S-CO2 storage tank is always maintained above the critical temperature.

5. The system according to claim 1, characterized in that, In the compression heat storage subsystem, both the heat storage heat exchanger and the heat release heat exchanger are counter-flow heat exchangers. Both the high-temperature hot water storage tank and the low-temperature hot water storage tank are pressurized and sealed hot water storage tanks. Under energy storage conditions, the high-temperature and high-pressure S-CO2 working fluid discharged from the main compressor unit exchanges heat with the low-temperature hot water storage water in a counter-flow manner through the heat storage heat exchanger, storing the heat generated during the compression process in the high-temperature hot water storage tank. Under energy release conditions, the working fluid discharged from the high-pressure S-CO2 storage tank first enters the heat release heat exchanger, exchanges heat with the high-temperature pressurized hot water storage water discharged from the high-temperature hot water storage tank in a counter-flow manner, and completes the first-stage heat replenishment in the energy release stage. After the high-temperature hot water storage water releases heat, it flows back to the low-temperature hot water storage tank, forming a closed compression heat storage and release loop.

6. The system according to claim 1, characterized in that, In the multi-energy cascade heat replenishment subsystem, the waste heat exchanger of the S-CO2 heat pump unit is connected to the waste heat loop of the park on the hot side to absorb low-grade waste heat of 50~70 ℃. The low-grade waste heat includes at least air conditioning condensing heat and / or data center cooling waste heat. The heat pump compressor, heat pump heat exchanger, heat pump regenerator, heat pump expander, and waste heat exchanger are connected by pipelines to form a closed loop. The S-CO2 working fluid is compressed by the heat pump compressor and enters the heat pump heat exchanger to release heat. After expanding, cooling, and depressurizing by the heat pump expander, it enters the waste heat exchanger to absorb low-grade waste heat. After heat exchange with the compressed high-temperature S-CO2 working fluid in the heat pump regenerator, it returns to the heat pump compressor. The whole system constitutes a regenerative reverse Brayton cycle with a rated operating performance coefficient of 2.5~3.

5. The heat pump heat exchanger further heats the S-CO2 working fluid after the first-stage heat replenishment to 150~200℃. ℃, to achieve secondary heat replenishment of S-CO2 working fluid during the energy release stage.

7. The system according to claim 1 or 6, characterized in that, In the multi-energy cascade heat replenishment subsystem, the solar thermal concentrator module adopts a tower-type heliostat concentrating heat collection structure. A closed molten salt circulation loop is formed between the high-temperature molten salt storage tank and the low-temperature molten salt storage tank. The low-temperature molten salt working fluid is heated by the solar thermal concentrator module and then stored in the high-temperature molten salt storage tank. During the energy release stage, it is further heated to above 450 ℃ by the molten salt heat exchanger to the S-CO2 working fluid that has been preheated by the main regenerator, thus achieving three-stage heat replenishment of the S-CO2 working fluid. The molten salt temperature at the outlet of the molten salt heat exchanger is controlled above the molten salt freezing point. Furthermore, during periods of surplus renewable electricity, the solar thermal concentrator molten salt heat storage unit pre-replenishes the molten salt loop with heat storage through electric heating modules installed in the high-temperature molten salt storage tank and / or the low-temperature molten salt storage tank.

8. The system according to claim 1, characterized in that, In the expansion and regeneration subsystem, the main regenerator is a plate regenerator. After the secondary reheating, the S-CO2 working fluid enters the cold side of the main regenerator and exchanges heat countercurrently with the high-temperature working fluid discharged from the expander unit on the hot side of the main regenerator to recover the medium- and high-temperature waste heat in the expansion exhaust steam. This raises the working fluid temperature to 300~400℃ before it enters the molten salt heat exchanger. The main expander unit is a multi-stage axial flow expander with an inlet working fluid temperature of over 450℃. Its expansion ratio is matched with the pressure ratio of the main compressor unit. The outlet pressure of the expanded working fluid is controlled at 7.8~8.7 MPa, and it drives the generator set connected to it to generate electricity, realizing the conversion of the working fluid's thermal energy and pressure potential energy into electrical energy.

9. The system according to claim 1, characterized in that, The system also includes a terminal waste heat recovery heat exchanger located between the hot-side outlet of the main regenerator and the inlet of the low-pressure S-CO2 storage tank. Its hot side is connected to a 0.1 MPa atmospheric pressure water circuit, which is used to convert the residual low-temperature waste heat after expansion work and main regeneration into heating heat for winter heating and / or domestic hot water for the park. The S-CO2 working fluid after terminal waste heat recovery is returned to the low-pressure S-CO2 storage tank in a supercritical state of 33-39 ℃ and 7.7-8.6 MPa.

10. The system according to claim 1, characterized in that, A first bypass branch with a bypass valve is connected in parallel between the inlet and outlet of the cold side channel of the heat pump heat exchanger; a second bypass branch with a bypass valve is connected in parallel between the inlet and outlet of the hot side channel of the main regenerator; and a third bypass branch with a bypass valve is connected in parallel between the inlet and outlet of the cold side channel of the molten salt heat exchanger. Each bypass branch is used to bypass and regulate the working fluid flow of the corresponding heat exchanger when the corresponding heat exchanger is started, operating at low load, switching operating conditions, or when the temperature exceeds the limit, so as to regulate the temperature difference on both sides of the corresponding heat exchanger, control the outlet temperature and pressure of the working fluid, and suppress heat source fluctuations, load changes, or operating condition thermal shock and flow resistance fluctuations.

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