Power supply system based on CO2 battery-CO2 power cycle

Abstract

The utility model relates to the technical field of physical energy storage and thermal power generation, in particular to a power supply system based on CO2 battery-CO2 power cycle, which comprises a power supply network, a photovoltaic power generation system, a thermal power generation system, a molten salt system, a heat energy storage system and a CO2 battery-CO2 power cycle system. Wherein the CO2 battery-CO2 power circulation system is connected with the power supply network and used for converting heat energy entering the CO2 battery-CO2 power circulation system into electric energy, and the electric energy is stored with CO2 as an energy storage medium or directly input into the power supply network. According to the power supply system, the electric energy input of the power supply network can be flexibly regulated and controlled through the molten salt system, the heat energy storage system and the CO2 battery-CO2 power circulation system, so that the power supply system keeps dynamic balance, the power supply network can stably supply power to a user after photovoltaic power generation is introduced, and the power utilization requirement of the user is met.

Description

Technical Field

[0001] The utility model relates to the technical field of physical energy storage and thermal power generation, and more specifically, to a power supply system based on a CO2 battery-CO2 power cycle. Background Art

[0002] With the rapid development of renewable energy sources such as wind and solar power, their introduction into the power grid can easily disrupt the balance of the power supply system. Because these renewable energy sources depend on the external environment and are random and intermittent, their introduction can easily disrupt the balance of the power supply system. Furthermore, electricity demand varies at different times of the day and in different seasons, further increasing the difficulty of maintaining a dynamic balance in the power supply system. Consequently, the introduction of renewable energy sources such as solar power makes it difficult to align peak power generation and peak power consumption, making it difficult to maintain a dynamic balance and achieving stable power supply. Utility Model Content

[0003] The purpose of this utility model is to overcome the deficiency of the existing technology that the power supply system is difficult to maintain dynamic balance after the introduction of new energy power generation such as solar power generation, and to provide a power supply system based on CO2 battery-CO2 power cycle. This solution can flexibly regulate the power input of the power supply network, so that the power supply system maintains dynamic balance, and the power supply network can provide stable power supply to users.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] Provided is a power supply system based on a CO2 battery-CO2 power cycle, including a power supply grid, a photovoltaic power generation system, a thermal power generation system, a molten salt system, a thermal energy storage system, and a CO2 battery-CO2 power cycle system:

[0006] The power supply network is used to transmit electric energy to users;

[0007] The photovoltaic power generation system is connected to the power supply grid to input electric energy into the power supply grid;

[0008] The thermal power generation system is connected to the molten salt system to transfer heat energy generated by the thermal power generation system to the molten salt system;

[0009] The molten salt system is connected to the thermal energy storage system and the CO2 battery-CO2 power cycle system to transfer the thermal energy in the molten salt system to the thermal energy storage system and the CO2 battery-CO2 power cycle system;

[0010] The thermal energy storage system is connected to the CO2 battery-CO2 power cycle system to store thermal energy from the molten salt system and transfer thermal energy to the CO2 battery-CO2 power cycle system;

[0011] The CO2 battery-CO2 power cycle system is connected to the power supply grid to convert the thermal energy entering the CO2 battery-CO2 power cycle system into electrical energy, and store the electrical energy using CO2 as an energy storage medium or directly input it into the power supply grid.

[0012] When the power supply system of the present invention is in operation, the electricity generated by the photovoltaic power generation system is directly transmitted to the power grid, which then transmits the electricity to users for use. The heat energy generated by the thermal power generation system during operation is absorbed by the molten salt system after passing through it. The molten salt system transfers part of the heat from the thermal power generation system to the thermal energy storage system for storage; the other part is transferred to the CO2 battery-CO2 power cycle system. Simultaneously, the thermal energy storage system can also transfer the heat energy to the CO2 battery-CO2 power cycle system. The CO2 battery-CO2 power cycle system can convert the heat energy into electrical energy and input it into the power grid. It can also store the electrical energy using CO2 as an energy storage medium. When the electricity generated by the photovoltaic power generation system is sufficient to meet the user's usage needs, the heat generated by the thermal power generation system is distributed through the molten salt system. Part of the heat is stored in the thermal energy storage system, and the other part enters the CO2 battery-CO2 power cycle system. The CO2 battery-CO2 power cycle system converts the heat into electrical energy and stores it using CO2 as an energy storage medium. When the electricity generated by the photovoltaic power generation system is insufficient to meet the user's needs, the heat generated by the thermal power generation system is distributed through the molten salt system, with a portion of the heat being stored in the thermal energy storage system and the remaining heat entering the CO2 battery-CO2 power cycle system. The CO2 battery-CO2 power cycle system converts the heat into electrical energy and then feeds the electrical energy into the power grid to meet the user's electricity needs. When the electrical energy generated by the photovoltaic power generation system and the thermal power generation system is still insufficient to meet the user's electricity needs after being fed into the power grid, the thermal energy in the thermal energy storage system is fed into the CO2 battery-CO2 power cycle system, increasing the power generation of the CO2 battery-CO2 power cycle system. At the same time, the CO2 battery-CO2 power cycle system also releases the electrical energy stored using CO2 as the energy storage medium, further increasing the power generation of the CO2 battery-CO2 power cycle system and thereby increasing the electrical energy fed into the power grid to meet the user's electricity needs.

[0013] The power supply system based on the CO2 battery-CO2 power cycle of the utility model can flexibly regulate the power input of the power supply network through the molten salt system, the thermal energy storage system and the CO2 battery-CO2 power cycle system, so that the power supply system maintains a dynamic balance. After the introduction of photovoltaic power generation, the power supply network can provide stable power supply to users and meet their electricity needs.

[0014] Preferably, the CO2 battery-CO2 power cycle system includes: a CO2 Brayton / Brayton-Rankine cycle subsystem, a CO2 energy storage subsystem and a LiBr absorption refrigeration system.

[0015] The CO2 energy storage subsystem is used to input CO2 to the CO2 Brayton / Brayton-Rankine cycle subsystem or receive CO2 from the CO2 Brayton / Brayton-Rankine cycle subsystem;

[0016] The CO2 Brayton / Brayton-Rankine cycle subsystem is connected to the CO2 energy storage subsystem and the LiBr absorption refrigeration system to generate electricity based on the CO2 provided by the CO2 energy storage subsystem;

[0017] The LiBr absorption refrigeration system is used to refrigerate the CO2 of the CO2 energy storage subsystem based on the waste heat of the CO2 Brayton / Brayton-Rankine cycle subsystem and the heat from the thermal energy storage system.

[0018] When the ambient temperature is high and the grid load is low, the CO2 Brayton / Brayton-Rankine cycle subsystem and the LiBr absorption refrigeration system are coupled. The LiBr absorption refrigeration system uses the waste heat from the CO2 Brayton / Brayton-Rankine cycle subsystem and the heat energy entering the CO2 battery-CO2 power cycle system to cool the CO2 and store it in the CO2 energy storage subsystem, completing energy storage. When the ambient temperature is low and the grid load is low, the CO2 can be cooled by the external low-temperature environment and stored in the CO2 energy storage subsystem. Alternatively, the LiBr absorption refrigeration system and the CO2 energy storage subsystem can be coupled to cool the CO2 by the LiBr absorption refrigeration system and store it in the CO2 energy storage subsystem. When the grid load is high, the waste heat from the CO2 Brayton / Brayton-Rankine cycle subsystem and the heat energy entering the CO2 battery-CO2 power cycle system are used to evaporate the CO2 in the CO2 energy storage subsystem. The CO2 entering the CO2 Brayton / Brayton-Rankine cycle subsystem then generates power, releasing energy.

[0019] Preferably, the CO2 environment in the low-pressure CO2 storage tank is 8.5MPa and 25°C. The CO2 environment in the high-pressure CO2 storage tank is 25MPa and 25°C. The CO2 in both the low-pressure CO2 storage tank and the high-pressure CO2 storage tank is liquid, so it is necessary to ensure that the internal gas pressure is greater than the liquid critical gas pressure of CO2. The pressure inside the high-pressure CO2 storage tank is greater, which makes the CO2 density inside it higher and the storage capacity greater. When the pressures of the low-pressure CO2 tank and the high-pressure CO2 tank are 8.5MPa and 25MPa respectively, their thermal efficiency can reach 49.3%, while the case without energy storage system coupling is about 48.2%, the efficiency increases by about 1.1%, and the output power increases by about 20%.

[0020] Preferably, the LiBr absorption refrigeration system includes a generator, a condenser, an evaporator and an absorber connected in sequence, a regenerator, a pump three and a first throttle valve are provided between the generator and the absorber, the CO2 in the absorber passes through the pump three and the regenerator in sequence and enters the generator; the CO2 in the generator passes through the regenerator and the first throttle valve in sequence and enters the absorber, and a second throttle valve is provided between the condenser and the evaporator.

[0021] First, the circulating stream, carrying waste heat from the power cycle, passes through the generator to evaporate the LiBr solution. The stream is divided into two sections: The concentrated LiBr solution, after releasing heat, expands and cools through the first throttle valve before entering the absorber. It mixes with saturated water from the evaporator to form a dilute LiBr solution. This solution enters pump 3 for pressurization, flows into the regenerator for heating, and then enters the generator, completing the solution cycle. The superheated water vapor in the second section flows into the condenser for cooling, becoming cooler superheated steam or saturated steam. It then flows into the second throttle valve for expansion and cooling, reaching a temperature of approximately 6°C. It enters the evaporator (Eva) to cool the CO2 stream or store cold energy, absorbing heat before entering the absorber.

[0022] Preferably, the CO2 Brayton / Brayton-Rankine cycle subsystem comprises a Brayton-Rankine hybrid cycle system, which includes a heat source heater, a high-temperature regenerator, an intermediate-temperature regenerator, a low-temperature regenerator, a recompressor, a cooler, and a pump 4. The CO2 in the turbine sequentially passes through the high-temperature regenerator, the intermediate-temperature regenerator, and the low-temperature regenerator before entering the cooler. The CO2 in the cooler sequentially passes through the pump 4, the low-temperature regenerator, the intermediate-temperature regenerator, the high-temperature regenerator, and the heat source heater before entering the turbine. The CO2 flowing out of the intermediate-temperature regenerator also passes through the recompressor and flows into the high-temperature regenerator. The CO2 flowing out of the low-temperature regenerator also passes through the main compressor and flows into the intermediate-temperature regenerator. The Brayton-Rankine hybrid cycle system is capable of storing energy under high temperatures and low grid load.

[0023] Preferably, the CO2 Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, which includes a heat source heater, a high-temperature regenerator, a low-temperature regenerator, a recompressor, and a cooler. The CO2 in the turbine sequentially passes through the high-temperature regenerator and the low-temperature regenerator to enter the cooler; the CO2 in the cooler sequentially passes through the main compressor, the low-temperature regenerator, the high-temperature regenerator, and the heat source heater to enter the turbine; the CO2 flowing out of the low-temperature regenerator also passes through the recompressor and flows into the high-temperature regenerator. The recompression Brayton power cycle system can store energy when the temperature is low and the power grid load is light, and can also release energy when the power grid load is heavy, reducing the power supply pressure of the power grid.

[0024] Preferably, when the recompression Brayton power cycle system is performing energy storage, the high-temperature, high-pressure CO2 flowing out of the main compressor passes through the regenerator, is condensed into liquid CO2 at 25 MPa and 25°C, and is stored in the high-pressure CO2 storage tank. The CO2 flowing out of the turbine passes through the high-temperature regenerator and the low-temperature regenerator, releasing the CO2 waste heat, and then passes through the cooler to raise the CO2 temperature to 35°C.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] The utility model provides a power supply system based on a CO2 battery-CO2 power cycle, which can flexibly regulate the power input of the power supply network through a molten salt system, a thermal energy storage system and a CO2 battery-CO2 power cycle system, so that the power supply system maintains a dynamic balance. The power supply network can provide stable power supply to users and meet their electricity needs.

[0027] The CO2 battery-CO2 power cycle system in this utility model's power supply system based on a CO2 battery-CO2 power cycle can operate differently during energy storage, depending on the season. This system stores surplus grid electricity or seasonal renewable energy sources such as excess solar energy in the CO2 energy storage subsystem, reducing the amount of electricity input to the grid. During energy release, the energy storage system is connected to the power generation cycle, releasing energy, increasing the power output of the power generation cycle, and increasing the amount of electricity input to the grid. This energy storage system can fully utilize existing power plant equipment, reducing costs, and the power generation system can adapt to various heat source scenarios and achieve flexible peak load regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a module diagram of a power supply system based on a CO2 battery-CO2 power cycle;

[0029] Figure 2A schematic diagram of the working state of a thermal power generation system in a power supply system based on a CO2 battery-CO2 power cycle when storing energy;

[0030] Figure 3 A schematic diagram of the working state of a thermal power generation system in a power supply system based on a CO2 battery-CO2 power cycle when supplying power;

[0031] Figure 4 A schematic diagram of the working state of a CO2 battery-CO2 power cycle system in a power supply system based on a CO2 battery-CO2 power cycle when supplying power;

[0032] Figure 5 This is a block diagram of a LiBr absorption refrigeration system in a power supply system based on a CO2 battery-CO2 power cycle;

[0033] Figure 6 A flow chart of the energy release cycle of the CO2 Brayton / Brayton-Rankine cycle subsystem in a power supply system based on a CO2 battery-CO2 power cycle, where arrows indicate the CO2 flow direction;

[0034] Figure 7 A flow chart of a low-temperature energy storage cycle for a CO2 Brayton / Brayton-Rankine cycle subsystem in a power supply system based on a CO2 battery-CO2 power cycle, where arrows indicate the flow of CO2.

[0035] Figure 8 A flow chart of another low-temperature energy storage cycle for a CO2 Brayton / Brayton-Rankine cycle subsystem in a power supply system based on a CO2 battery-CO2 power cycle, where arrows indicate the flow of CO2.

[0036] Figure 9 This is a flow chart of the high-temperature energy storage cycle of the CO2 Brayton / Brayton-Rankine cycle subsystem in a power supply system based on the CO2 battery-CO2 power cycle. The arrows in the figure indicate the flow direction of CO2.

[0037] In the attached figure: 100, power supply grid; 200, photovoltaic power generation system; 300, thermal power generation system; 400, molten salt system; 500, thermal energy storage system; 600, CO2 battery-CO2 power cycle system; 1, low-pressure CO2 storage tank; 2, high-pressure CO2 storage tank; 3, first cooler; 4, second cooler; 5, pump one; 6, pump two; 7, generator; 8, condenser; 9, evaporator; 10, absorber; 11, regenerator; 12, pump three; 13, first throttle valve; 14, heat source heater; 15, turbine; 16, high-temperature regenerator; 17, medium-temperature regenerator; 18, low-temperature regenerator; 19, main compressor; 20, recompressor; 21, cooler; 22, pump four. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic, not actual, representations. They should not be construed as limiting this patent. To better illustrate the embodiments of the present invention, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted from the drawings.

[0039] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and so on indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0040] Example 1

[0041] This embodiment is the first embodiment of a power supply system based on a CO2 battery-CO2 power cycle, including a power supply grid 100, a photovoltaic power generation system 200, a thermal power generation system 300, a molten salt system 400, a thermal energy storage system 500, and a CO2 battery-CO2 power cycle system 600:

[0042] The power grid 100 is used to deliver electrical energy to users;

[0043] The photovoltaic power generation system 200 is connected to the power grid 100 to input electric energy into the power grid 100;

[0044] The thermal power generation system 300 is connected to the molten salt system 400 to transfer the heat energy generated by the thermal power generation system 300 to the molten salt system 400;

[0045] The molten salt system 400 is connected to the thermal energy storage system 500 and the CO2 battery-CO2 power cycle system 600 to transfer the thermal energy in the molten salt system 400 to the thermal energy storage system 500 and the CO2 battery-CO2 power cycle system 600;

[0046] The thermal energy storage system 500 is connected to the CO2 battery-CO2 power cycle system 600 to store thermal energy from the molten salt system 400 and transfer thermal energy to the CO2 battery-CO2 power cycle system 600;

[0047] The CO2 battery-CO2 power cycle system 600 is connected to the power grid 100 to convert the heat energy entering the CO2 battery-CO2 power cycle system 600 into electrical energy, and store the electrical energy using CO2 as an energy storage medium or directly input it into the power grid 100.

[0048] The working principle and working process of this embodiment are as follows:

[0049] When the power supply system is operating, the electricity generated by the photovoltaic power generation system 200 is directly transmitted to the power supply grid 100, which then transmits the electricity to users for use. The heat energy generated by the thermal power generation system 300 during operation is absorbed by the molten salt system 400 after passing through it. The molten salt system 400 transfers part of the heat from the thermal power generation system 300 to the thermal energy storage system 500 for storage; the other part is transferred to the CO2 battery-CO2 power cycle system 600. At the same time, the thermal energy storage system 500 can also transfer heat energy to the CO2 battery-CO2 power cycle system 600. The CO2 battery-CO2 power cycle system 600 can convert heat energy into electrical energy and input it into the power supply grid 100. It can also store electrical energy using CO2 as an energy storage medium.

[0050] like Figure 2 As shown, when the electricity generated by the photovoltaic power generation system 200 is sufficient to meet the user's usage needs, the heat generated by the thermal power generation system 300 is distributed through the molten salt system 400, and part of the heat is stored in the thermal energy storage system 500, and the other part of the heat enters the CO2 battery-CO2 power cycle system 600. The CO2 battery-CO2 power cycle system 600 converts the heat into electricity and stores it in CO2 as the energy storage medium. Figure 3 As shown, when the electricity generated by the photovoltaic power generation system 200 is insufficient to meet the user's demand, the heat generated by the thermal power generation system 300 is distributed through the molten salt system 400, and part of the heat is stored in the thermal energy storage system 500, while the other part enters the CO2 battery-CO2 power cycle system 600. The CO2 battery-CO2 power cycle system 600 converts the heat into electrical energy and then inputs the electrical energy into the power grid 100 to meet the user's electricity demand. Figure 4As shown, when the electric energy generated by the photovoltaic power generation system 200 and the thermal power generation system 300 is input into the power supply grid 100 but is still insufficient to meet the electricity demand of the user, the thermal energy in the thermal energy storage system is input into the CO2 battery-CO2 power cycle system 600, thereby increasing the power generation of the CO2 battery-CO2 power cycle system 600. At the same time, the CO2 battery-CO2 power cycle system 600 will also release the electric energy stored in CO2 as the energy storage medium, thereby further increasing the power generation of the CO2 battery-CO2 power cycle system 600, thereby increasing the electric energy input into the power supply grid 100, thereby meeting the electricity demand of the user.

[0051] The beneficial effects of this embodiment are as follows:

[0052] The power supply system of this embodiment can flexibly regulate the power input of the power supply grid 100 through the molten salt system 400, the thermal energy storage system 500 and the CO2 battery-CO2 power cycle system 600, so that the power supply system maintains a dynamic balance. After the introduction of photovoltaic power generation, the power supply grid 100 can provide stable power supply to users to meet their electricity needs.

[0053] Example 2

[0054] This embodiment is a second embodiment of a power supply system based on a CO2 battery-CO2 power cycle. Based on the first embodiment, this embodiment further defines the CO2 battery-CO2 power cycle system 600.

[0055] Specifically, the CO2 battery-CO2 power cycle system 600 includes: a CO2 Brayton / Brayton-Rankine cycle subsystem, a CO2 energy storage subsystem and a LiBr absorption refrigeration system.

[0056] The CO2 energy storage subsystem is used to input CO2 to the CO2 Brayton / Brayton-Rankine cycle subsystem or receive CO2 from the CO2 Brayton / Brayton-Rankine cycle subsystem;

[0057] The CO2 Brayton / Brayton-Rankine cycle subsystem is connected to the CO2 energy storage subsystem and the LiBr absorption refrigeration system to generate electricity based on the CO2 provided by the CO2 energy storage subsystem;

[0058] The LiBr absorption refrigeration system is used to refrigerate the CO2 of the CO2 energy storage subsystem based on the waste heat of the CO2 Brayton / Brayton-Rankine cycle subsystem and the heat from the thermal energy storage system 500.

[0059] Specifically, such as Figure 4As shown, the CO2 energy storage subsystem includes a main compressor 19, a turbine 15, and a low-pressure CO2 storage tank 1, pump 1 5, a first cooler 3, pump 2 6, a second cooler 4, and a high-pressure CO2 storage tank 2, which are connected in sequence. The low-pressure CO2 storage tank 1 is connected to the main compressor 19 and turbine 15 via a CO2 Brayton / Brayton-Rankine cycle subsystem. After being cooled by the low-temperature environment, the low-pressure liquid CO2 is pressurized and cooled by a two-stage pump and two intercoolers 21 and 21 before being stored in the high-pressure CO2 storage tank 2.

[0060] Specifically, the CO2 environment in the low-pressure CO2 storage tank 1 is 8.5 MPa and 25° C. The CO2 environment in the high-pressure CO2 storage tank 2 is 25 MPa and 25° C.

[0061] Specifically, such as Figure 1 As shown, the LiBr absorption refrigeration system includes a generator 7, a condenser 8, an evaporator 9 and an absorber 10 connected in sequence. A regenerator 11, a pump 3 12 and a first throttle valve 13 are provided between the generator 7 and the absorber 10. The working fluid in the absorber 10 passes through the pump 3 12 and the regenerator 11 in sequence and enters the generator 7; the working fluid in the generator 7 passes through the regenerator 11 and the first throttle valve 13 in sequence and enters the absorber 10. A second throttle valve is provided between the condenser 8 and the evaporator 9.

[0062] Specifically, the CO2 Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, which includes a heat source heater 14, a high-temperature regenerator 16, a low-temperature regenerator 18, a recompressor 20 and a cooler 21. The working fluid in the turbine 15 passes through the high-temperature regenerator 16 and the low-temperature regenerator 18 in sequence and enters the cooler 21; the working fluid in the cooler 21 passes through the main compressor 19, the low-temperature regenerator 18, the high-temperature regenerator 16 and the heat source heater 14 in sequence and enters the turbine 15; the working fluid flowing out of the low-temperature regenerator 18 also passes through the recompressor 20 and flows into the high-temperature regenerator 16.

[0063] Specifically, when the recompression Brayton power cycle system is storing energy, the high-temperature, high-pressure CO2 flowing out of the main compressor 19 passes through the regenerator 11, where it is condensed into liquid CO2 at 25 MPa and 25°C and stored in the high-pressure CO2 storage tank 2. The CO2 flowing out of the turbine 15 passes through the high-temperature regenerator 16 and the low-temperature regenerator 18, where it releases waste heat and then passes through the cooler 21, raising the CO2 temperature to 35°C.

[0064] The working principle and working process of this embodiment are as follows:

[0065] When ambient temperature is high and grid load is low, the CO2 Brayton / Brayton-Rankine cycle subsystem and the LiBr absorption refrigeration system are coupled. The LiBr absorption refrigeration system uses the waste heat from the CO2 Brayton / Brayton-Rankine cycle subsystem to cool the CO2 and store it in the CO2 energy storage subsystem, completing energy storage. The specific process is as follows: the low-temperature, low-pressure CO2 flowing out of the low-pressure CO2 storage tank 1 passes through the regenerator 11, absorbing the waste heat of the high-temperature, high-pressure CO2 entering the high-temperature regenerator 16. After being heated to a preset temperature, it is mixed with the main circulating flow and enters the inlet of the main compressor 19, which consumes additional electricity or work to compress the CO2. The CO2 flowing out of the main compressor 19 is split. One stream passes through the evaporator 9 and is condensed into liquid CO2 at 25 MPa and 25°C and stored in the high-pressure CO2 storage tank 2. The other stream continues as the main circulating stream and flows into the medium-temperature regenerator 17. At the outlet of the medium-temperature regenerator 17, it mixes with the CO2 stream from the recompressor 20. The mixed CO2 flows through the high-temperature regenerator 16, the heat source heater 14, and the turbine 15 in sequence. The turbine 15 performs work and outputs electrical energy, which can be fed into the power grid or supplied to the main compressor 19 for energy storage. After the CO2 at the outlet of the turbine 15 flows through the high-temperature regenerator 16 and the medium-temperature regenerator 17 to release waste heat, it flows into the cooler 21 to exchange heat with the environment, raising its temperature to 35°C, completing a cycle.

[0066] When the ambient temperature is low and the grid load is light, the CO2 can be cooled by the external low-temperature environment and stored in the CO2 energy storage subsystem. Alternatively, a LiBr absorption refrigeration system can be coupled with the CO2 energy storage subsystem to cool the CO2 by the LiBr absorption refrigeration system and store it in the CO2 energy storage subsystem. The specific process is as follows: the low-pressure liquid CO2 flowing out of the low-pressure CO2 storage tank 1 is cooled by the low-temperature environment, then pressurized and cooled by a two-stage pump and two coolers 21 before being stored in the high-pressure CO2 storage tank 2. The pump can be driven by a turbine 15.

[0067] When the CO2 battery-CO2 power cycle system 600 releases energy, it includes the following working steps: First, high-pressure liquid CO2 flows out of the high-pressure CO2 storage tank 2, with a pressure and temperature of 25MPa and 25°C respectively, and flows into the regenerator 11 to evaporate until the temperature of the CO2 flowing out of the regenerator 11 is the same as the temperature of the CO2 at the outlet of the main compressor 19. The CO2 flowing out of the regenerator 11 and the CO2 at the outlet of the main compressor 19 are mixed and then flow to the low-pressure CO2 storage tank 1 through the diverter. After being condensed to 25°C in the cold storage tank, it is stored in the low-pressure CO2 storage tank 1. The storage pressure of the low-pressure CO2 storage tank 1 is 8.5MPa, which is the same as the CO2 pressure at the inlet of the main compressor 19.

[0068] The beneficial effects of this embodiment are as follows:

[0069] The CO2 battery-CO2 power cycle system 600 of this embodiment has multiple operating modes during the energy storage stage. It can make full use of the cold source in the low-temperature environment and increase the energy storage power when there is sufficient cold energy. It is only strongly coupled with the pump or main compressor 19 of the power cycle, has strong flexibility, and has almost no impact on other equipment in the power cycle.

[0070] Example 3

[0071] This embodiment is the third embodiment of a power supply system based on a CO2 battery-CO2 power cycle. This embodiment is similar to the second embodiment, except that the structure of the CO2 Brayton / Brayton-Rankine cycle subsystem is different.

[0072] Specifically, the sCO2-CO2 Brayton-hybrid cycle system includes a Brayton-Rankine hybrid cycle system, and the Brayton-Rankine hybrid cycle system includes a heat source heater 14, a high-temperature regenerator 16, a medium-temperature regenerator 17, a low-temperature regenerator 18, a recompressor 20, a cooler 21 and a pump four. The working fluid in the turbine 15 passes through the high-temperature regenerator 16, the medium-temperature regenerator 17 and the low-temperature regenerator 18 in sequence and enters the cooler 21; the working fluid in the cooler 21 passes through the pump four, the low-temperature regenerator 18, the medium-temperature regenerator 17, the high-temperature regenerator 16 and the heat source heater 14 in sequence and enters the turbine 15; the working fluid flowing out of the medium-temperature regenerator 17 also passes through the recompressor 20 and flows into the high-temperature regenerator 16; the working fluid flowing out of the low-temperature regenerator 18 also passes through the main compressor 19 and flows into the medium-temperature regenerator 17.

[0073] The working principle and working process of this embodiment are as follows:

[0074] The liquid CO2 at the outlet of the low-pressure CO2 storage tank 1 flows into the cooler 21, is cooled by the low-temperature environment, flows into the mixer, is mixed with the main circulation flow, flows into the pump and is pressurized. The pressurized CO2 is diverted by the diverter, one stream passes through the regenerator 11 and flows into the high-temperature regenerator 16, and the other stream flows into the low-temperature regenerator 18 in the main circulation. The CO2 flowing into the low-temperature regenerator 18 evaporates into supercritical CO2 through the low-temperature regenerator 18 and is mixed with the CO2 at the outlet of the main compressor 19 in the mixer. The mixed CO2 flows into the medium-temperature regenerator 17 to absorb heat. The CO2 flowing out of the medium-temperature regenerator 17 is mixed with the CO2 at the outlet of the recompressor 20 and then flows into the high-temperature regenerator 16 and the heat source heater 14 in sequence to absorb heat. The CO2 after absorbing heat enters the turbine 15 to expand and do work. The CO2 flowing out of the turbine 15 flows through the high-temperature regenerator 16 and the medium-temperature regenerator 17 to release waste heat. The CO2 at the outlet of the medium-temperature regenerator 17 is split in the splitter, one stream flows into the recompressor 20, and the other flows into the low-temperature regenerator 18; one stream of CO2 flowing out of the low-temperature regenerator 18 enters the main compressor 19 for compression, and the other stream is cooled into liquid by the environment and coupled with the energy storage system to complete a cycle.

[0075] Other features and beneficial effects of this embodiment are the same as those of the second embodiment.

[0076] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. A person skilled in the art will be able to make other variations or modifications based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A power supply system based on CO2 battery-CO2 power cycle, characterized in that: The system comprises a power supply grid (100), a photovoltaic power generation system (200), a thermal power generation system (300), a molten salt system (400), a thermal energy storage system (500), and a CO2 battery-CO2 power cycle system (600): The power supply network (100) is used to transmit electric energy to users; The photovoltaic power generation system (200) is connected to the power supply network (100) to input electric energy into the power supply network (100); The thermal power generation system (300) is connected to the molten salt system (400) to transfer heat energy generated by the thermal power generation system (300) to the molten salt system (400); The molten salt system (400) is connected to the thermal energy storage system (500) and the CO2 battery-CO2 power cycle system (600) to transfer the thermal energy in the molten salt system (400) to the thermal energy storage system (500) and the CO2 battery-CO2 power cycle system (600); The thermal energy storage system (500) capable of storing thermal energy from the molten salt system (400) is connected to the CO2 battery-CO2 power cycle system (600) to transfer the stored thermal energy to the CO2 battery-CO2 power cycle system (600); The CO2 battery-CO2 power cycle system (600) is connected to the power supply network (100) to convert heat energy entering the CO2 battery-CO2 power cycle system (600) into electrical energy, and the electrical energy is stored using CO2 as an energy storage medium or directly input into the power supply network (100).

2. A power supply system based on CO2 battery-CO2 power cycle according to claim 1, characterized in that: The CO2 battery-CO2 power cycle system (600) comprises: a CO2 Brayton / Brayton-Rankine cycle subsystem, a CO2 energy storage subsystem and a LiBr absorption refrigeration system. The CO2 energy storage subsystem is used to input CO2 to the CO2 Brayton / Brayton-Rankine cycle subsystem or receive CO2 from the CO2 Brayton / Brayton-Rankine cycle subsystem; The CO2 Brayton / Brayton-Rankine cycle subsystem is connected to the CO2 energy storage subsystem and the LiBr absorption refrigeration system to generate electricity based on the CO2 provided by the CO2 energy storage subsystem; The LiBr absorption refrigeration system is used to refrigerate the CO2 of the CO2 energy storage subsystem based on the waste heat of the CO2 Brayton / Brayton-Rankine cycle subsystem and the heat from the thermal energy storage system (500).

3. A power supply system based on CO2 battery-CO2 power cycle according to claim 2, characterized in that: The CO2 energy storage subsystem includes a main compressor (19), a turbine (15), and a low-pressure CO2 storage tank (1), a pump 1 (5), a first cooler (3), a pump 2 (6), a second cooler (4) and a high-pressure CO2 storage tank (2) connected in sequence. The low-pressure CO2 storage tank (1) is connected to the main compressor (19) and the turbine (15) through the CO2 Brayton / Brayton-Rankine cycle subsystem.

4. A power supply system based on CO2 battery-CO2 power cycle according to claim 3, characterized in that: The pressure of CO2 in the high-pressure CO2 storage tank (2) is not less than 25 MPa and the temperature is not less than 25°C.

5. A power supply system based on CO2 battery-CO2 power cycle according to claim 3, characterized in that: The pressure of CO2 in the low-pressure CO2 storage tank (1) is not less than 8.5 MPa, and the temperature is lower than 25°C.

6. A power supply system based on CO2 battery-CO2 power cycle according to claim 3, characterized in that: The LiBr absorption refrigeration system comprises a generator (7), a condenser (8), an evaporator (9) and an absorber (10) connected in sequence, a regenerator (11), a pump three (12) and a first throttle valve (13) are provided between the generator (7) and the absorber (10), CO2 in the absorber (10) passes through the pump three (12) and the regenerator (11) in sequence and enters the generator (7); CO2 in the generator (7) passes through the regenerator (11) and the first throttle valve (13) in sequence and enters the absorber (10), and a second throttle valve is provided between the condenser (8) and the evaporator (9).

7. A power supply system based on CO2 battery-CO2 power cycle according to claim 6, characterized in that: The CO2 Brayton / Brayton-Rankine cycle subsystem includes a Brayton-Rankine hybrid cycle system, and the Brayton-Rankine hybrid cycle system includes a heat source heater (14), a high temperature regenerator (16), a medium temperature regenerator (17), a low temperature regenerator (18), a recompressor (20), a cooler (21) and a pump 4. The CO2 in the turbine (15) passes through the high-temperature regenerator (16), the medium-temperature regenerator (17) and the low-temperature regenerator (18) in sequence and enters the cooler (21); The CO2 in the cooler (21) sequentially passes through the pump 4, the low-temperature regenerator (18), the medium-temperature regenerator (17), the high-temperature regenerator (16) and the heat source heater (14) and enters the turbine (15); The CO2 flowing out of the medium-temperature regenerator (17) also passes through the recompressor (20) and flows into the high-temperature regenerator (16); the CO2 flowing out of the low-temperature regenerator (18) also passes through the main compressor (19) and flows into the medium-temperature regenerator (17).

8. A power supply system based on CO2 battery-CO2 power cycle according to claim 6, characterized in that: The CO2 Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, and the recompression Brayton power cycle system includes a heat source heater (14), a high-temperature regenerator (16), a low-temperature regenerator (18), a recompressor (20) and a cooler (21). The CO2 in the turbine (15) passes through the high-temperature regenerator (16) and the low-temperature regenerator (18) in sequence and enters the cooler (21); The CO2 in the cooler (21) passes through the main compressor (19), the low-temperature regenerator (18), the high-temperature regenerator (16) and the heat source heater (14) in sequence and enters the turbine (15); The CO2 flowing out of the low-temperature regenerator (18) also passes through the recompressor (20) and flows into the high-temperature regenerator (16).

9. A power supply system based on CO2 battery-CO2 power cycle according to claim 8, characterized in that: When the recompression Brayton power cycle system is storing energy, the high-temperature and high-pressure CO2 flowing out of the main compressor (19) is condensed into liquid CO2 at 25 MPa and 25°C after passing through the regenerator (11) and stored in the high-pressure CO2 storage tank (2).

10. A power supply system based on CO2 battery-CO2 power cycle according to claim 8, characterized in that: When the recompression Brayton power cycle system is storing energy, the CO2 flowing out of the turbine (15) releases the waste heat of CO2 after passing through the high-temperature regenerator (16) and the low-temperature regenerator (18), and then flows through the cooler (21) to increase the temperature of CO2 to 35°C.

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