A coupled system of battery energy storage and compressed carbon dioxide energy storage

Abstract

The present invention discloses a coupling system of battery energy storage and compressed carbon dioxide energy storage, comprising a compressed carbon dioxide energy storage system and an electrochemical energy storage system. The battery pack of the electrochemical energy storage system is arranged in a carbon dioxide flexible gas storage chamber and surrounded by carbon dioxide. The gas in the carbon dioxide flexible gas storage chamber sequentially passes through a fan, the hot side of a battery heat release heat exchanger and returns to the carbon dioxide flexible gas storage chamber through a second outlet. The cold side outlet of the battery heat release heat exchanger is sequentially connected to form a loop through a second high-temperature water storage tank, a high-temperature water tank outlet pump, the hot side of a coupling heat exchanger, a second low-temperature water storage tank, a low-temperature water tank outlet pump and the cold side inlet of the battery heat release heat exchanger. The cold side of the coupling heat exchanger is connected between the cold side of the evaporator of the compressed carbon dioxide energy storage system and the cold side of a second heat exchanger. In the present invention, the battery pack is placed in a carbon dioxide environment, so that safety problems such as battery spontaneous combustion and explosion can be avoided during operation, and the generated impurity gas is safely treated through the carbon dioxide energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply or distribution circuit systems, and particularly relates to a coupling system of battery energy storage and compressed carbon dioxide energy storage. Background Art

[0002] With the continuous increase in the proportion of new energy sources such as wind power and photovoltaic power in the energy structure, energy storage has become a key supporting technology for the large-scale utilization of renewable energy. Among various energy storage technologies, electrochemical energy storage is a reasonable solution to solve the problem of new energy consumption, enhance the stability of the power grid, and improve the utilization efficiency of the distribution system. It is one of the most widely applied and promising power energy storage technologies at present, and can play an important role in the entire power value chain, covering all aspects of power generation, transmission, distribution, and consumption. Compared with traditional energy storage methods, its outstanding advantages lie in its flexible application scenarios, not being restricted by special geographical conditions, short construction period, high conversion efficiency, etc.

[0003] Electrochemical energy storage mainly includes various secondary batteries, such as lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries, and flow batteries. These batteries are relatively mature in technology and have become the focus of attention in recent years. However, they have the risk of spontaneous combustion and are prone to safety problems. For example, in 2019, at the McMicken electrochemical energy storage power station in Arizona, USA, due to battery thermal runaway, combustible gas caught fire and exploded; in 2021, at the Beijing Jimei Dahongmen electrochemical energy storage power station, combustible gas accumulated and caught fire and exploded; in 2020, at the Carnegie Road electrochemical energy storage power station in Liverpool, UK, due to battery thermal runaway, combustible gas caught fire and exploded, etc. Therefore, it is urgent to take measures to solve the problem of spontaneous combustion and reduce the probability of dangerous accidents. At present, there is no system that can achieve 100% safe operation of electrochemical energy storage power stations.

[0004] CO2 is non-toxic and non-flammable, and is usually used in the fire protection field. In addition, the CO2 critical point (7.39 MPa and 31.4 °C) is relatively easy to reach compared with air (3.77 MPa and -140.5 °C). Its dew point is higher than that of air, and it can condense at a temperature close to room temperature under high pressure. The storage density of CO2 is greater than that of air under the same state and pressure, and it is the highest when stored in liquid state. Therefore, the carbon dioxide energy storage system has high energy storage potential. As a new type of compressed gas energy storage technology, carbon dioxide energy storage has attracted extensive attention and research in recent years due to its excellent physical properties of energy storage working medium, stable system performance, and compact process equipment.

[0005] If carbon dioxide is used as the working fluid, it is possible to ensure the safety of the electrochemical energy storage system in a CO2 atmosphere, significantly improving the safety of the electrochemical energy storage system. In addition, placing the electrochemical energy storage on the low-pressure side of the compressed carbon dioxide energy storage can save land while ensuring safety and has the potential to reduce costs. At the same time, the response speeds of the two have their own characteristics and can cooperate with each other to better respond to grid commands. Currently, there is no complete system that deeply couples the two. Therefore, combining electrochemical energy storage with compressed carbon dioxide energy storage has obvious application prospects. Summary of the Invention

[0006] In view of the problems existing in the background technology, the present invention provides a coupling system for battery energy storage and compressed carbon dioxide energy storage, which is characterized by including: a compressed carbon dioxide energy storage system and an electrochemical energy storage system; the electrochemical energy storage system includes: a battery pack, a coupling heat exchanger, a battery heat release heat exchanger, a second low-temperature water storage tank, a second high-temperature water storage tank, and a fan; wherein the battery pack is arranged in a carbon dioxide flexible gas storage chamber and surrounded by carbon dioxide, and the gas in the carbon dioxide flexible gas storage chamber passes through the fan, the hot side of the battery heat release heat exchanger, and the second inlet of the carbon dioxide flexible gas storage chamber in sequence through the second outlet; the cold side outlet of the battery heat release heat exchanger is connected in sequence through the high-temperature water storage tank, the high-temperature water tank outlet pump, the hot side of the coupling heat exchanger, the second low-temperature water storage tank, the low-temperature water tank outlet pump, and the cold side inlet of the battery heat release heat exchanger to form a loop;

[0007] The compressed carbon dioxide energy storage system includes: a carbon dioxide flexible gas storage chamber, a first compressor, a first turbine, a first heat exchanger, a second heat exchanger, a high-temperature heat storage medium storage tank, a low-temperature heat storage medium storage tank, a condenser, an evaporator, a carbon dioxide high-pressure storage tank, a separator, a first low-temperature water storage tank, a first high-temperature water storage tank, and a post-cooler; wherein the gas in the flexible gas storage chamber passes through the first compressor, the hot side of the first heat exchanger, the hot side of the condenser, the separator, the carbon dioxide high-pressure storage tank, the throttle valve, the cold side of the evaporator, the cold side of the coupling heat exchanger, the cold side of the second heat exchanger, the first turbine, the hot side of the post-cooler, and the first inlet of the carbon dioxide flexible gas storage chamber in sequence through the first outlet;

[0008] The cold side of the first heat exchanger returns to form a loop after passing through the high-temperature heat storage medium storage tank, the hot side of the second heat exchanger, and the low-temperature heat storage medium storage tank in sequence;

[0009] The outlet of the first high-temperature water storage tank is connected to the inlet of the first low-temperature water storage tank through a pump and the hot side of the evaporator; the inlet of the cold side of the condenser and the inlet of the cold side of the post-cooler are both connected to the outlet of the first low-temperature water storage tank; the outlet of the cold side of the condenser and the outlet of the cold side of the post-cooler are both connected to the inlet of the first high-temperature water storage tank.

[0010] The battery pack uses ternary lithium batteries, lithium iron phosphate batteries, sodium sulfur batteries that have spontaneous combustion problems, or uses waste batteries.

[0011] When the average temperature of the batteries in the carbon dioxide flexible gas storage chamber is higher than 35°C, the second outlet of the carbon dioxide flexible gas storage chamber and the fan are opened, and the gas in the carbon dioxide flexible gas storage chamber enters the battery heat release heat exchanger through the fan to release heat.

[0012] The number of expansion stages in the compressed carbon dioxide energy storage system is multiple. At least one set of additional heat exchangers and additional turbines are installed on the pipeline between the second heat exchanger and the first turbine. The hot sides of the additional heat exchangers on the discharge side are connected to the pipeline between the hot side of the second heat exchanger and the low-temperature heat storage medium storage tank.

[0013] The number of compression stages in the compressed carbon dioxide energy storage system is multiple. At least one set of additional heat exchangers and additional compressors are installed on the pipeline between the first compressor and the first heat exchanger. The cold sides of the additional heat exchangers on the charging side are connected to the pipeline between the low-temperature heat storage medium storage tank and the cold side of the first heat exchanger.

[0014] In the coupled system of battery energy storage and compressed carbon dioxide energy storage described, the gas is liquefied after passing through the hot side of the condenser. Then, in the separator, the impurity gas generated by the battery will be separated from the liquid carbon dioxide.

[0015] When the battery pack works, heat is stored for the carbon dioxide in the carbon dioxide flexible gas storage chamber. When the average temperature of the batteries in the carbon dioxide flexible gas storage chamber is higher than 35°C, the gas in the carbon dioxide flexible gas storage chamber flows out through the second outlet to the fan and then enters the battery heat release heat exchanger, exchanges heat with the water from the second low-temperature water storage tank, and then returns to the carbon dioxide flexible gas storage chamber. The water from the second low-temperature water storage tank enters the battery heat release heat exchanger through the low-temperature water tank outlet pump for heat exchange; thus, the gas in the carbon dioxide flexible gas storage chamber is cooled down, and the heat-exchanged water enters the second high-temperature water storage tank to store the thermal energy.

[0016] When the compressed carbon dioxide energy storage system performs charging energy storage:

[0017] The gas in the carbon dioxide flexible gas storage chamber sequentially passes through the first outlet, the first compressor, the hot side of the first heat exchanger, the hot side of the condenser, and the separator and enters the carbon dioxide high-pressure storage tank, and absorbs electrical energy for charging in the first compressor; at the same time, the medium in the low-temperature heat storage medium storage tank is heated by the first heat exchanger and then enters the high-temperature heat storage medium storage tank for storage.

[0018] On the hot side of the condenser, gaseous carbon dioxide exchanges heat with the water from the first low-temperature water storage tank. After heat exchange, the carbon dioxide becomes liquid, while the other impurity gases remain in their original state. Subsequently, the other impurity gases are separated by the separator and then transported to the carbon dioxide high-pressure storage tank. The water in the first low-temperature water storage tank enters the cold side of the condenser for heat exchange and is then transported to the first high-temperature water storage tank.

[0019] When the compressed carbon dioxide energy storage system discharges and releases energy:

[0020] Open the throttle valve for the compressed carbon dioxide energy storage system to discharge and release energy. The carbon dioxide working medium flowing out of the carbon dioxide high-pressure storage tank sequentially passes through the throttle valve, the cold side of the evaporator, the cold side of the coupling heat exchanger, the cold side of the second heat exchanger, the first turbine for work, and the hot side of the aftercooler. The carbon dioxide working medium with a slightly increased temperature compared to when it flows out of the first outlet finally returns to the carbon dioxide flexible gas storage chamber;

[0021] During this process, in the evaporator, the carbon dioxide from the high-pressure storage tank exchanges heat with the water from the first high-temperature water storage tank. After heat exchange, the carbon dioxide is transported to the coupling heat exchanger, and the heat-exchanged water is transported to the first low-temperature water storage tank;

[0022] In the aftercooler, the expanded carbon dioxide exchanges heat with the water in the first low-temperature water storage tank. After releasing heat on the hot side, the carbon dioxide enters the carbon dioxide flexible gas storage chamber, and after absorbing heat on the cold side, the water enters the first high-temperature water storage tank;

[0023] On the cold side of the second heat exchanger, the working medium from the high-temperature heat storage medium storage tank releases heat on the cold side of the second heat exchanger and then enters the low-temperature heat storage medium storage tank for storage.

[0024] When the carbon dioxide working medium flows through the cold side of the coupling heat exchanger, if there is sufficient heat stored in the second high-temperature water storage tank, the water from the second high-temperature water storage tank releases heat through the coupling heat exchanger and then flows into the second low-temperature water storage tank for storage.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The battery pack is directly placed in the carbon dioxide flexible gas storage chamber. Operating in a carbon dioxide environment can avoid safety problems such as battery self-ignition and explosion, and the heat and impurity gases generated are released into the carbon dioxide flexible gas storage chamber.

[0027] 2. The battery pack placed in a carbon dioxide environment has no risk of self-ignition and can be combined with various types and capacities of batteries, such as ternary lithium batteries, lithium iron phosphate batteries, sodium sulfur batteries that have self-ignition problems, or used batteries. If cascade batteries are used, the cost of the electrochemical energy storage system can be significantly reduced.

[0028] 3. Placing the electrochemical energy storage in the flexible carbon dioxide gas storage chamber can save land and improve the overall economy of the system.

[0029] 4. The impurity gas (flammable gas) generated by the battery in the separator will be separated from the liquid carbon dioxide, which is convenient for subsequent treatment and has high safety.

[0030] 5. During operation, the electrochemical energy storage system and the compressed carbon dioxide energy storage system are deeply coupled. It can make full use of the speed difference between battery energy storage and carbon dioxide energy storage in variable load, and can also make full use of the ability of carbon dioxide energy storage in inertia support. When the two work simultaneously, they can cooperate with each other in load regulation speed. During actual operation, the two can also operate independently. The operation mode of this system is flexible and can fully meet the load regulation requirements of the power grid. Brief Description of the Drawings

[0031] Figure 1 It is the process flow diagram of Embodiment 1 of a coupling system of battery energy storage and compressed carbon dioxide energy storage according to the present invention.

[0032] Figure 2 It is the process flow diagram of Embodiment 2 of the present invention.

[0033] Among them, 100 - compressed carbon dioxide energy storage system; 101 - flexible carbon dioxide gas storage chamber; 102 - first compressor; 103 - additional first - stage compressor; 104 - additional first - stage turbine; 105 - first turbine; 106 - first heat exchanger; 107 - second heat exchanger; 108 - additional first - stage heat exchanger on the charging side; 109 - additional first - stage heat exchanger on the discharging side; 110 - high - temperature heat storage medium storage tank; 111 - low - temperature heat storage medium storage tank; 112 - condenser; 113 - evaporator; 114 - carbon dioxide high - pressure storage tank; 115 - separator; 116 - first low - temperature water storage tank; 117 - first high - temperature water storage tank; 118 - after - cooler; 119 - throttle valve; 200 - electrochemical energy storage system; 201 - battery pack; 202 - coupling heat exchanger; 203 - battery heat - releasing heat exchanger; 204 - second low - temperature water storage tank; 205 - second high - temperature water storage tank; 206 - fan; 207 - low - temperature water tank outlet pump; 208 - high - temperature water tank outlet pump. Detailed Embodiment

[0034] The following further elaborates on the present invention with reference to the drawings.

[0035] As Figure 1Embodiment 1 of the present invention shown in the figure includes: a compressed carbon dioxide energy storage system 100 and an electrochemical energy storage system 200 under a carbon dioxide atmosphere; wherein, the electrochemical energy storage system 200 includes: a battery pack 201, a coupled heat exchanger 202, a battery heat release heat exchanger 203, a second low-temperature water storage tank 204, a second high-temperature water storage tank 205, a high-temperature water tank outlet pump 208, a low-temperature water tank outlet pump 207, and a fan 206; wherein the battery pack 201 is arranged in a carbon dioxide flexible gas storage chamber 101 and surrounded by carbon dioxide. The gas in the carbon dioxide flexible gas storage chamber 101 is sequentially connected through the second outlet, the fan 206, the hot side of the battery heat release heat exchanger 203, and the second inlet of the carbon dioxide flexible gas storage chamber 101, and carbon dioxide is used in the pipeline of this loop; the cold side outlet of the battery heat release heat exchanger 203 sequentially passes through the high-temperature water storage tank 205, the high-temperature water tank outlet pump 208, the hot side of the coupled heat exchanger 202, the second low-temperature water storage tank 204, the low-temperature water tank outlet pump 207, and the cold side inlet of the battery heat release heat exchanger 203 to form a loop, and a heating medium is used in the pipeline of this loop; the battery pack 201 can be a ternary lithium battery, a lithium iron phosphate battery, a sodium-sulfur battery, etc. that have spontaneous combustion problems, or waste batteries can also be used to achieve cascade utilization. Because the battery pack 201 is under a carbon dioxide atmosphere, safety problems such as battery spontaneous combustion and explosion can be avoided, and the generated impurity gases can be easily separated.

[0036] The compressed carbon dioxide energy storage system 100 includes: a carbon dioxide flexible gas storage chamber 101, a first compressor 102, a first turbine 105, a first heat exchanger 106, a second heat exchanger 107, a high-temperature heat storage medium storage tank 110, a low-temperature heat storage medium storage tank 111, a condenser 112, an evaporator 113, a carbon dioxide high-pressure storage tank 114, a separator 115, a first low-temperature water storage tank 116, a first high-temperature water storage tank 117, a post-cooler 118, and a throttle valve 119; wherein the gas in the carbon dioxide flexible gas storage chamber 101 is sequentially connected through the first outlet, the first compressor 102, the hot side of the first heat exchanger 106, the hot side of the condenser 112, the separator 115, the carbon dioxide high-pressure storage tank 114, the throttle valve 119, the cold side of the evaporator 113, the cold side of the coupled heat exchanger 202, the cold side of the second heat exchanger 107, the first turbine 105, the hot side of the post-cooler 118, and the first inlet of the carbon dioxide flexible gas storage chamber 101, and carbon dioxide is used in the pipeline of this loop;

[0037] The cold side of the first heat exchanger 106 sequentially passes through the high-temperature heat storage medium storage tank 110, the hot side of the second heat exchanger 107, and the low-temperature heat storage medium storage tank 111 and then returns to form a loop, and a heating medium is used in the pipeline of this loop;

[0038] The outlet of the first high-temperature water storage tank 117 is connected to the inlet of the first low-temperature water storage tank 116 through a pump, the hot side of the evaporator 113. The inlets of the cold sides of the condenser 112 (cooling medium inlets) and the post-cooler 118 (cooling medium inlets) are both connected to the outlet of the first low-temperature water storage tank 116; the outlets of the cold sides of the condenser 112 (cooling medium outlets) and the post-cooler 118 (cooling medium outlets) are both connected to the inlet of the first high-temperature water storage tank 117. Water is used in the pipelines of this circuit.

[0039] During operation, the electrochemical energy storage system 200 and the compressed carbon dioxide energy storage system 100 are deeply coupled, enabling mutual cooperation in load regulation speed and separation of battery exhaust gas; at the same time, they can also operate independently. Therefore, the system operation is divided into the following modes: when the battery pack 201 is working, the electrochemical energy storage system 200 stores heat, the compressed carbon dioxide energy storage system 100 charges and stores energy, the compressed carbon dioxide energy storage system 100 discharges and releases energy, coupled charging and heat storage (the compressed carbon dioxide energy storage system 100 charges and stores energy while the battery pack 201 is working), and coupled discharging and heat absorption (the compressed carbon dioxide energy storage system 100 discharges and releases energy while the battery pack 201 is working).

[0040] When the battery pack 201 is working, the electrochemical energy storage system 200 stores heat:

[0041] First, charge or discharge the battery pack 201 in the electrochemical energy storage system 200 to store heat for the carbon dioxide in the carbon dioxide flexible gas storage chamber 101. When the average temperature of the batteries in the carbon dioxide flexible gas storage chamber 101 is higher than 35°C, the gas in the carbon dioxide flexible gas storage chamber 101 flows out through the second outlet to the fan 206 and then enters the battery heat release heat exchanger 203, exchanges heat with the water from the second low-temperature water storage tank 204 and then returns to the carbon dioxide flexible gas storage chamber 101. The water from the second low-temperature water storage tank 204 enters the battery heat release heat exchanger 203 through the low-temperature water tank outlet pump 207 for heat exchange, and then cools down the gas in the carbon dioxide flexible gas storage chamber 101. The heat-exchanged water enters the second high-temperature water storage tank 205 to store the thermal energy.

[0042] When the compressed carbon dioxide energy storage system 100 charges and stores energy:

[0043] The gas in the carbon dioxide flexible gas storage chamber 101 sequentially passes through the first compressor 102, the hot side of the first heat exchanger 106, the hot side of the condenser 112, and the separator 115 and enters the carbon dioxide high-pressure storage tank 114, and absorbs electrical energy in the first compressor 102 for charging; at the same time, the medium in the low-temperature heat storage medium storage tank 111 is heated by the first heat exchanger 106 and then enters the high-temperature heat storage medium storage tank 110 for storage;

[0044] On the hot side of the condenser 112, gaseous carbon dioxide exchanges heat with the water from the first low-temperature water storage tank 116. After heat exchange, the carbon dioxide becomes liquid while the other impurity gases remain in their original state. Subsequently, the other impurity gases are separated by the separator 115 and then transported to the carbon dioxide high-pressure storage tank 114. The water in the first low-temperature water storage tank 116 enters the cold side of the condenser 112 for heat exchange and is then transported to the first high-temperature water storage tank 117;

[0045] When the compressed carbon dioxide energy storage system 100 discharges energy:

[0046] Open the throttle valve 119 to discharge and release energy from the compressed carbon dioxide energy storage system 100. The carbon dioxide working fluid flowing out of the carbon dioxide high-pressure storage tank 114 successively passes through the throttle valve 119, absorbs heat and warms up on the cold side of the evaporator 113, absorbs heat and warms up on the cold side of the coupling heat exchanger 202, absorbs heat and warms up on the cold side of the second heat exchanger 107, does work (discharges and releases energy) on the first turbine 105, and releases heat and cools down on the hot side of the aftercooler 118. Finally, the carbon dioxide working fluid with a slightly increased temperature compared to when it flows out of the first outlet returns to the carbon dioxide flexible gas storage chamber 101;

[0047] During this process, in the evaporator 113, the carbon dioxide from the high-pressure storage tank 114 exchanges heat with the water from the first high-temperature water storage tank 117. After heat exchange, the carbon dioxide is transported to the coupling heat exchanger 202, and the heat-exchanged water is transported to the first low-temperature water storage tank 116;

[0048] On the cold side of the second heat exchanger 107, the working fluid from the high-temperature heat storage medium storage tank 110 releases heat on the cold side of the second heat exchanger 107 and then enters the low-temperature heat storage medium storage tank 111 for storage;

[0049] In the aftercooler 118, the expanded carbon dioxide exchanges heat with the water in the first low-temperature water storage tank 116. After releasing heat on the hot side, the carbon dioxide enters the carbon dioxide flexible gas storage chamber 101, and after absorbing heat on the cold side, the water enters the first high-temperature water storage tank 117;

[0050] When the carbon dioxide working fluid flows through the cold side of the coupling heat exchanger 202, if there is sufficient heat stored in the second high-temperature water storage tank 205, the coupling heat exchanger 202 in the circuit of the compressed carbon dioxide energy storage system 100 operates. The water from the second high-temperature water storage tank 205 releases heat through the coupling heat exchanger 202 and then flows into the second low-temperature water storage tank 204 for storage, that is, the heat in the second high-temperature water storage tank 205 is released to the carbon dioxide through the coupling heat exchanger 202 to realize the utilization of thermal energy;

[0051] Since a throttle valve 119 is provided between the high-pressure storage tank 114 and the evaporator 113; the pressure and temperature of the liquid carbon dioxide from the high-pressure storage tank 114 are both reduced after passing through the throttle valve 119, and then it is transported into the evaporator 113 for heat exchange.

[0052] As Figure 2 shown in Embodiment 2 of the present invention, the un-described parts are the same as those in Embodiment 1;

[0053] In the compressed carbon dioxide energy storage system 100 of Embodiment 1, the number of turbines, compressors and heat exchangers serving as expanders can be increased or decreased as the case may be. The compressed carbon dioxide energy storage system 100 can be a single-stage expansion or a multi-stage expansion (multi-stage charging energy storage). At the same time, the compressed carbon dioxide energy storage system 100 can also be a single-stage compression or a multi-stage compression (multi-stage discharging energy release);

[0054] Embodiment 2 provides an embodiment of two-stage expansion and two-stage compression. Specifically, an additional first-stage compressor 103, an additional first-stage turbine 104, a charging-side additional first-stage heat exchanger 108 and a discharging-side additional first-stage heat exchanger 109 are newly added to the compressed carbon dioxide energy storage system 100. Among them, the charging-side additional first-stage heat exchanger 108 and the additional first-stage compressor 103 are installed on the pipeline between the first compressor 102 and the first heat exchanger 106, and the additional first-stage turbine 104 and the discharging-side additional first-stage heat exchanger 109 are installed on the pipeline between the second heat exchanger 107 and the first turbine 105. Thus, after the outlet of the high-temperature heat storage medium storage tank 110 releases heat through the hot side of the second heat exchanger 107 and the hot side of the discharging-side additional first-stage heat exchanger 109, it enters the low-temperature heat storage medium storage tank 111. The outlet of the low-temperature heat storage medium storage tank 111 enters the high-temperature heat storage medium storage tank 110 for storage after absorbing heat through the cold side of the charging-side additional first-stage heat exchanger 108 and the cold side of the first heat exchanger 106 to form a loop;

[0055] In the charging-side additional first-stage heat exchanger 108, the carbon dioxide compressed by the first compressor 102 exchanges heat with the heat storage medium from the low-temperature heat storage medium storage tank 111. The heat-exchanged carbon dioxide is transported into the additional first-stage compressor 103 for re-compression, and the heat-exchanged heat storage medium is transported into the first heat exchanger 106 to continue to exchange heat and cool down with the carbon dioxide flowing out of the charging-side additional first-stage heat exchanger 108;

[0056] In the second heat exchanger 107, carbon dioxide from the coupled heat exchanger 202 exchanges heat with the heat storage medium from the high-temperature heat storage medium storage tank 110. The carbon dioxide after heat exchange is transported to the additional first-stage turbine 104 for expansion work, and then transported to the heating medium from the hot side of the second heat exchanger 107 in the additional first-stage heat exchanger 109 on the discharge side for further heat exchange and temperature rise. The carbon dioxide after heat exchange is transported to the first turbine 105 for expansion work, and then transported to the aftercooler 118 to exchange heat with the low-temperature water from the first low-temperature water storage tank 116. The heat storage medium after heat exchange is transported to the low-temperature heat storage medium storage tank 111.

[0057] Similarly, if there are multiple additional heat exchangers and additional turbines on the discharge side, then on the pipeline between the second heat exchanger 107 and the first turbine 105, each group of additional heat exchangers and additional turbines on the discharge side is installed according to the process. The hot sides of the additional heat exchangers on each discharge side are connected to the pipeline between the hot side of the second heat exchanger 107 and the low-temperature heat storage medium storage tank 111 according to the process.

[0058] If there are multiple additional heat exchangers and additional compressors on the charging side, then on the pipeline between the first compressor 102 and the first heat exchanger 106, each group of additional heat exchangers and additional compressors on the charging side is installed according to the process. The cold sides of the additional heat exchangers on each charging side are connected to the pipeline between the low-temperature heat storage medium storage tank 111 and the cold side of the first heat exchanger 106 according to the process.

Claims

1. A coupled system of battery energy storage and compressed carbon dioxide energy storage, characterized in that, Including: A compressed carbon dioxide energy storage system (100) and an electrochemical energy storage system (200); The electrochemical energy storage system (200) includes: a battery pack (201), a coupled heat exchanger (202), a battery heat release heat exchanger (203), a second low-temperature water storage tank (204), a second high-temperature water storage tank (205), and a fan (206); wherein the battery pack (201) is arranged inside a carbon dioxide flexible gas storage chamber (101) and surrounded by carbon dioxide. The gas in the carbon dioxide flexible gas storage chamber (101) sequentially passes through the fan (206), the hot side of the battery heat release heat exchanger (203), and is connected to the second inlet of the carbon dioxide flexible gas storage chamber (101) through the second outlet; the cold side outlet of the battery heat release heat exchanger (203) sequentially passes through the second high-temperature water storage tank (205), the high-temperature water tank outlet pump (208), the hot side of the coupled heat exchanger (202), the second low-temperature water storage tank (204), the low-temperature water tank outlet pump (207), and the cold side inlet of the battery heat release heat exchanger (203) to form a loop; The compressed carbon dioxide energy storage system (100) includes: a carbon dioxide flexible gas storage chamber (101), a first compressor (102), a first turbine (105), a first heat exchanger (106), a second heat exchanger (107), a high-temperature heat storage medium storage tank (110), a low-temperature heat storage medium storage tank (111), a condenser (112), an evaporator (113), a carbon dioxide high-pressure storage tank (114), a separator (115), a first low-temperature water storage tank (116), a first high-temperature water storage tank (117), and a post-cooler (118); wherein the gas in the carbon dioxide flexible gas storage chamber (101) sequentially passes through the first compressor (102), the hot side of the first heat exchanger (106), the hot side of the condenser (112), the separator (115), the carbon dioxide high-pressure storage tank (114), a throttle valve (119), the cold side of the evaporator (113), the cold side of the coupled heat exchanger (202), the cold side of the second heat exchanger (107), the first turbine (105), the hot side of the post-cooler (118), and is connected to the first inlet of the carbon dioxide flexible gas storage chamber (101) through the first outlet; The cold side of the first heat exchanger (106) sequentially passes through the high-temperature heat storage medium storage tank (110), the hot side of the second heat exchanger (107), and the low-temperature heat storage medium storage tank (111) and then returns to form a loop; The outlet of the first high-temperature water storage tank (117) is connected to the inlet of the first low-temperature water storage tank (116) through a pump and the hot side of the evaporator (113); the inlets of the cold side of the condenser (112) and the cold side of the post-cooler (118) are both connected to the outlet of the first low-temperature water storage tank (116); the outlets of the cold side of the condenser (112) and the cold side of the post-cooler (118) are both connected to the inlet of the first high-temperature water storage tank (117).

2. The coupled system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, wherein The battery pack (201) uses ternary lithium batteries, lithium iron phosphate batteries, sodium sulfur batteries with self-ignition problems, or uses waste batteries.

3. A coupling system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, When the average temperature of the batteries in the CO₂ flexible gas storage chamber (101) is higher than 35°C, the second outlet of the CO₂ flexible gas storage chamber (101) and the fan (206) are opened, and the gas in the CO₂ flexible gas storage chamber (101) enters the battery heat release heat exchanger (203) through the fan (206) to release heat.

4. A coupling system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, The number of expansion stages in the compressed CO₂ energy storage system (100) is multiple. At least one set of additional heat exchangers and additional turbines on the discharge side are installed on the pipeline between the second heat exchanger (107) and the first turbine (105). The hot sides of the discharge-side additional heat exchangers are connected to the pipeline between the hot side of the second heat exchanger (107) and the low-temperature heat storage medium storage tank (111).

5. A coupling system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, The number of compression stages in the compressed CO₂ energy storage system (100) is multiple. At least one set of additional heat exchangers and additional compressors on the charge side are installed on the pipeline between the first compressor (102) and the first heat exchanger (106). The cold sides of the charge-side additional heat exchangers are connected to the pipeline between the low-temperature heat storage medium storage tank (111) and the cold side of the first heat exchanger (106).

6. The coupled system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, The gas is liquefied after passing through the hot side of the condenser (112). Then, in the separator (115), the impurity gas generated by the battery is separated from the liquid CO₂.

7. A coupling system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, When the battery pack is working, heat is stored in the CO₂ in the CO₂ flexible gas storage chamber. When the average temperature of the batteries in the CO₂ flexible gas storage chamber is higher than 35°C, the gas in the CO₂ flexible gas storage chamber flows out through the second outlet, enters the battery heat release heat exchanger after passing through the fan, exchanges heat with the water from the second low-temperature water storage tank, and then returns to the CO₂ flexible gas storage chamber. The water from the second low-temperature water storage tank enters the battery heat release heat exchanger through the low-temperature water tank outlet pump for heat exchange. Then, the gas in the CO₂ flexible gas storage chamber is cooled down, and the heat-exchanged water enters the second high-temperature water storage tank to store the thermal energy.

8. A coupled system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, When the compressed CO₂ energy storage system is charged and stored: The gas in the CO₂ flexible gas storage chamber sequentially passes through the first compressor, the hot side of the first heat exchanger, the hot side of the condenser, and the separator through the first outlet and enters the CO₂ high-pressure storage tank, and absorbs electrical energy for charging in the first compressor. At the same time, the medium in the low-temperature heat storage medium storage tank is heated by the first heat exchanger and then enters the high-temperature heat storage medium storage tank for storage. On the hot side of the condenser, the gaseous CO₂ exchanges heat with the water from the first low-temperature water storage tank. After heat exchange, the CO₂ becomes liquid, while the states of other impurity gases remain unchanged. Then, the other impurity gases are separated through the separator and then transported to the CO₂ high-pressure storage tank. The water in the first low-temperature water storage tank enters the cold side of the condenser for heat exchange and then is transported to the first high-temperature water storage tank.

9. A coupled system of battery energy storage and compressed carbon dioxide energy storage according to claim 1, characterized in that, When the compressed CO₂ energy storage system discharges and releases energy: Open the throttle valve for the compressed CO₂ energy storage system to discharge and release energy. The CO₂ working medium flowing out of the CO₂ high-pressure storage tank sequentially passes through the throttle valve, the cold side of the evaporator, the cold side of the coupling heat exchanger, the cold side of the second heat exchanger, the first turbine to do work, and the hot side of the aftercooler. The CO₂ working medium with a slightly higher temperature than when flowing out of the first outlet finally returns to the CO₂ flexible gas storage chamber. During this process, in the evaporator, carbon dioxide from the high-pressure storage tank exchanges heat with water from the first high-temperature water storage tank. After heat exchange, the carbon dioxide is transported to the coupled heat exchanger, and the water after heat exchange is transported to the first low-temperature water storage tank; In the aftercooler, the expanded carbon dioxide exchanges heat with water in the first low-temperature water storage tank. After releasing heat on the hot side, the carbon dioxide enters the carbon dioxide flexible gas storage chamber, and after absorbing heat on the cold side, the water enters the first high-temperature water storage tank; On the cold side of the second heat exchanger, after the working fluid from the high-temperature heat storage medium storage tank releases heat on the cold side of the second heat exchanger, it enters the low-temperature heat storage medium storage tank for storage.

10. A coupled system of battery energy storage and compressed carbon dioxide energy storage according to claim 9, characterized in that, When the carbon dioxide working fluid flows through the cold side of the coupled heat exchanger, if there is enough heat stored in the second high-temperature water storage tank, the water from the second high-temperature water storage tank flows into the second low-temperature water storage tank for storage after releasing heat through the coupled heat exchanger.

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