Liquid carbon dioxide energy storage system

Abstract

The utility model relates to the technical field of energy storage, and provides a liquid carbon dioxide energy storage system. The utility model provides a liquid carbon dioxide energy storage system. The liquid carbon dioxide energy storage system comprises a charging storage tank, at least one compressor, a first liquefying device, a discharging storage tank, a power generation device and a second liquefying device, the charging storage tank can store low-pressure liquid carbon dioxide; the first liquefying device can liquefy carbon dioxide; the discharge storage tank can store low-pressure liquid carbon dioxide; the second liquefying device can liquefy carbon dioxide. The utility model provides a carbon dioxide energy storage system which is used for solving the technical problem that in the prior art, the occupied area for storing carbon dioxide gas at normal temperature and normal pressure is large.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a liquid carbon dioxide energy storage system. Background Art

[0002] Carbon dioxide energy storage technology is a new type of energy storage method that uses carbon dioxide, a gas, to store and release energy through physical changes. This technology has attracted attention because it can store energy efficiently and safely, and it shows great potential as the world's demand for clean energy increases. In addition, compared with traditional compressed air energy storage, carbon dioxide energy storage technology does not require special geographical locations, such as underground caves or salt caverns, to store gas. This means that we can build this energy storage system in more places without being restricted by geographical location. In addition, this technology does not rely on fossil fuels, helps reduce greenhouse gas emissions, and is in line with the current trend of reducing carbon emissions and promoting low-carbon development.

[0003] At present, the most common form of energy storage is low-pressure gas and high-pressure liquid. The working principle is very simple: when the demand for electricity is not high, the excess electricity is used to compress the carbon dioxide gas at room temperature and pressure into a high-pressure liquid and store it. At the same time, the heat generated during the compression process will also be stored. When the demand for electricity increases, the previously stored heat will be used to heat the liquid carbon dioxide to turn it into a gas, and then it will be converted into electricity through the work of the turbine to generate electricity.

[0004] However, the existing carbon dioxide energy storage system has a problem: carbon dioxide gas at normal temperature and pressure has a large volume and a low density, which requires a larger space to store, thus limiting the area occupied by the carbon dioxide energy storage system. Utility Model Content

[0005] The utility model provides a carbon dioxide energy storage system, which is used to solve the technical problem in the prior art that the carbon dioxide gas stored at normal temperature and pressure occupies a large area.

[0006] The utility model provides a liquid carbon dioxide energy storage system, comprising a charging storage tank, at least one compressor, a first liquefaction device, a discharge storage tank, a power generation device and a second liquefaction device which are sequentially connected to form a circulation loop; the charging storage tank can store low-pressure liquid carbon dioxide; the first liquefaction device can liquefy carbon dioxide; the discharge storage tank can store low-pressure liquid carbon dioxide; and the second liquefaction device can liquefy carbon dioxide.

[0007] According to one embodiment of the utility model, it also includes a first throttle valve and a gas-liquid separator; one end of the first throttle valve is connected to the first liquefaction device, and the other end of the first throttle valve is connected to the inlet of the gas-liquid separator; the gas outlet of the gas-liquid separator is connected to the inlet of the compressor; the liquid outlet of the gas-liquid separator is connected to the inlet of the discharge storage tank.

[0008] According to one embodiment of the utility model, the first liquefaction device includes a first sensible cold storage unit, a first cooler, a first normal temperature methanol tank, a first sensible cold recycling unit and a first low temperature methanol tank; the first sensible cold storage unit has a first heat exchange channel, a second heat exchange channel and a third heat exchange channel; the gas outlet of the gas-liquid separator is connected to the inlet of the compressor through the first heat exchange channel; the outlet of the compressor, the second heat exchange channel and the inlet of the gas-liquid separator are connected in sequence; the first sensible cold recycling unit has a fourth heat exchange channel and a fifth heat exchange channel; the discharge storage tank is connected to the power generation device through the fifth heat exchange channel; the third heat exchange channel, the first cooler, the first normal temperature methanol tank, the fourth heat exchange channel and the first low temperature methanol tank are connected in sequence to form a circulation loop.

[0009] According to one embodiment of the utility model, there are two compressors, namely, a first compressor and a second compressor; a heating device is also included, and the heating device includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a hot water tank, a normal temperature water tank and a second cooler; the first heat exchanger has a sixth heat exchange channel and a seventh heat exchange channel; the first heat exchanger is connected to the first compressor; the second heat exchanger has an eighth heat exchange channel and a ninth heat exchange channel; the second heat exchanger is connected to the second compressor; the third heat exchanger has a tenth heat exchange channel and an eleventh heat exchange channel; the fourth heat exchanger has a twelfth heat exchange channel and a thirteenth heat exchange channel; the gas-liquid The air outlet of the separator is connected to the inlet of the first compressor; the first compressor, the sixth heat exchange channel, the second compressor, the eighth heat exchange channel and the second heat exchange channel are connected in sequence; the inlet of the ninth heat exchanger channel and the inlet of the seventh heat exchanger channel are respectively connected to the outlet of the normal temperature water tank, and the outlet of the ninth heat exchanger channel and the outlet of the seventh heat exchanger channel are respectively connected to the inlet of the hot water tank; the outlet of the hot water tank is connected to the inlet of the second cooler through the tenth heat exchange channel and the twelfth heat exchange channel respectively; the outlet of the second cooler is connected to the inlet of the normal temperature water tank; the discharge storage tank, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel and the power generation device are connected in sequence.

[0010] According to one embodiment of the utility model, the second liquefaction device includes a second sensible cold storage unit, a second low-temperature methanol tank, a second sensible cold recycling unit, a third cooler and a second normal temperature methanol tank; the second sensible cold storage unit has a fourteenth heat exchange channel and a fifteenth heat exchange channel; the second sensible cold recycling unit has a sixteenth heat exchange channel and a seventeenth heat exchange channel; the charging storage tank, the fourteenth heat exchange channel and the first compressor are connected in sequence; the fifteenth heat exchange channel, the second low-temperature methanol tank, the sixteenth heat exchange channel, the third cooler and the second normal temperature methanol tank are connected in sequence; the discharge storage tank, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device, the seventeenth heat exchange channel and the charging storage tank are connected in sequence.

[0011] According to one embodiment of the utility model, the power generation device includes a first expander, a second expander and a generator; the first expander and the second expander are connected to the generator; the discharge tank, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander, the eleventh heat exchange channel, the second expander, the seventeenth heat exchange channel and the inlet of the charging tank are connected in sequence.

[0012] According to one embodiment of the utility model, it also includes a second throttle valve and a phase-change cold storage heat exchanger; the inlet of the second throttle valve is connected to the inlet of the charging tank; the phase-change cold storage heat exchanger has a first phase-change cold storage heat exchange channel and a second phase-change cold storage heat exchange channel; the outlet of the charging tank, the second throttle valve, the first phase-change cold storage heat exchange channel, the fourteenth heat exchange channel and the inlet of the first compressor are connected in sequence; the discharge tank, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device, the seventeenth heat exchange channel, the second phase-change cold storage heat exchange channel and the inlet of the charging tank are connected in sequence.

[0013] According to one embodiment of the utility model, it also includes a cryogenic pump, and the discharge tank, the cryogenic pump, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander, the eleventh heat exchange channel, the second expander, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging tank are connected in sequence.

[0014] According to one embodiment of the utility model, it also includes a fourth cooler, and the discharge tank, the cryogenic pump, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander, the eleventh heat exchange channel, the second expander, the fourth cooler, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging tank are connected in sequence.

[0015] According to one embodiment of the present invention, the compressor can be provided with electric energy by discarding electricity.

[0016] The characteristics and advantages of the carbon dioxide energy storage system of the utility model are:

[0017] In view of the problem that the storage of carbon dioxide gas at normal temperature and pressure in the prior art occupies a large area, the utility model proposes an innovative liquid carbon dioxide energy storage system. The system realizes efficient liquefaction and energy storage of carbon dioxide through the collaborative work of a series of components. Specifically, the system includes a charging tank, a compressor, a liquefaction device, a discharge tank and a power generation device, which are interconnected to form a circulation loop. The charging tank is used to store low-pressure liquid carbon dioxide and occupies a small space, while the compressor and the liquefaction device are responsible for compressing and liquefying the carbon dioxide gas at normal temperature and pressure, thereby further reducing the space required for storage. When the power demand is at a peak, the liquid carbon dioxide in the discharge tank will be heated and gasified, and converted into electrical energy through the power generation device to meet the power demand. The carbon dioxide that has passed through the power generation device is liquefied by the second liquefaction device and returned to the charging tank. This design not only solves the problem of large gas volume and wide area in traditional energy storage methods, but also improves the energy storage efficiency, making carbon dioxide energy storage technology more practical and environmentally friendly, and helping to promote the development of low-carbon energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of an implementation of the carbon dioxide energy storage system of the utility model;

[0020] Figure 2 It is a schematic diagram of another embodiment of the carbon dioxide energy storage system of the present invention.

[0021] Reference numerals:

[0022] 1. Charging storage tank; 2. Compressor; 21. First compressor; 22. Second compressor; 3. First liquefaction device; 31. First sensible cold storage unit; 32. First cooler; 33. First normal temperature methanol tank; 34. First sensible cold recycling unit; 35. First low temperature methanol tank; 4. Discharging storage tank; 5. Power generation device; 51. First expander; 52. Second expander; 53. Generator; 6. Second liquefaction device; 61. Second sensible cold storage unit; 62. The second low-temperature methanol tank; 63. The second sensible cold recycling unit; 64. The third cooler; 65. The second normal-temperature methanol tank; 7. The first throttle valve; 8. The gas-liquid separator; 9. The heating device; 91. The first heat exchanger; 92. The second heat exchanger; 93. The third heat exchanger; 94. The fourth heat exchanger; 95. The hot water tank; 96. The normal-temperature water tank; 97. The second cooler; 10. The second throttle valve; 11. The phase-change cold storage heat exchanger; 12. The low-temperature pump; 13. The fourth cooler. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be described clearly and completely in conjunction with the drawings in the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] In the description of the present embodiment, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present embodiment and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present embodiment.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this embodiment, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In this embodiment, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0027] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] Figure 1 to Figure 2 The carbon dioxide energy storage system provided by the utility model is shown. As can be seen from the figure, the utility model provides a liquid carbon dioxide energy storage system, including a charging tank 1, at least one compressor 2, a first liquefaction device 3, a discharge tank 4, a power generation device 5 and a second liquefaction device 6 which are sequentially connected to form a circulation loop; the charging tank 1 can store low-pressure liquid carbon dioxide; the first liquefaction device 3 can liquefy carbon dioxide; the discharge tank 4 can store low-pressure liquid carbon dioxide; the second liquefaction device 6 can liquefy carbon dioxide.

[0029] In specific implementation, in view of the problem of large area occupied by carbon dioxide gas storage at normal temperature and pressure in the prior art, the utility model proposes an innovative liquid carbon dioxide energy storage system. The system realizes efficient liquefaction and energy storage of carbon dioxide through the collaborative work of a series of components. Specifically, the system includes a charging tank 1, a compressor 2, a liquefaction device, a discharge tank 4 and a power generation device 5, which are interconnected to form a circulation loop. The charging tank 1 is used to store low-pressure liquid carbon dioxide, which occupies a small space, while the compressor 2 and the liquefaction device are responsible for compressing and liquefying carbon dioxide gas at normal temperature and pressure, thereby further reducing the space required for storage. At the peak of electricity demand, the liquid carbon dioxide in the discharge tank 4 will be heated and gasified, and converted into electrical energy through the power generation device 5 to meet the electricity demand. The carbon dioxide passing through the power generation device 5 is liquefied by the second liquefaction device 6 and then returned to the charging tank 1. This design not only solves the problem of large gas volume and wide area occupied in traditional energy storage methods, but also improves the energy storage efficiency, making carbon dioxide energy storage technology more practical and environmentally friendly, and helping to promote the development of low-carbon energy.

[0030] In this embodiment, the compressor 2 can be provided with electric energy by discarding electricity.

[0031] According to one embodiment of the utility model, it also includes a first throttle valve 7 and a gas-liquid separator 8; one end of the first throttle valve 7 is connected to the first liquefaction device 3, and the other end of the first throttle valve 7 is connected to the inlet of the gas-liquid separator 8; the gas outlet of the gas-liquid separator 8 is connected to the inlet of the compressor 2; the liquid outlet of the gas-liquid separator 8 is connected to the inlet of the discharge storage tank 4.

[0032] In specific implementation, the function of the first throttle valve 7 is to adjust the pressure, and it connects the first liquefaction device 3 and the gas-liquid separator 8. In the process of liquid carbon dioxide changing from a high-pressure state to a low-pressure state, the first throttle valve 7 ensures a smooth transition of pressure, which helps to improve the overall efficiency and safety of the system. The gas-liquid separator 8 is used to separate the liquid and gas in the liquid carbon dioxide. Its inlet end is connected to the other end of the first throttle valve 7, while the gas outlet and the liquid outlet are connected to the inlet of the compressor 2 and the inlet of the discharge tank 4, respectively. This design allows the system to effectively separate the gas component in the liquid carbon dioxide and store the pure liquid carbon dioxide in the discharge tank 4, while the separated gas is sent back to the compressor 2 for recompression, thereby forming an efficient cycle.

[0033] In this embodiment, the inlet of the gas-liquid separator 8 may be located at the left end thereof, the gas outlet of the gas-liquid separator 8 may be located at the upper end thereof, and the liquid outlet of the gas-liquid separator 8 may be located at the lower end thereof.

[0034] According to one embodiment of the utility model, the first liquefaction device 3 includes a first sensible cold storage unit 31, a first cooler 32, a first normal temperature methanol tank 33, a first sensible cold recycling unit 34 and a first low temperature methanol tank 35; the first sensible cold storage unit 31 has a first heat exchange channel, a second heat exchange channel and a third heat exchange channel; the gas outlet of the gas-liquid separator 8 is connected to the inlet of the compressor 2 through the first heat exchange channel; the outlet of the compressor 2, the second heat exchange channel and the inlet of the gas-liquid separator 8 are connected in sequence; the first sensible cold recycling unit 34 has a fourth heat exchange channel and a fifth heat exchange channel; the discharge storage tank 4 is connected to the power generation device 5 through the fifth heat exchange channel; the third heat exchange channel, the first cooler 32, the first normal temperature methanol tank 33, the fourth heat exchange channel and the first low temperature methanol tank 35 are connected in sequence to form a circulation loop.

[0035] In specific implementation, the first sensible cold storage unit 31 is responsible for storing the cold energy released by liquid carbon dioxide. It includes three heat exchange channels, namely the first heat exchange channel, the second heat exchange channel and the third heat exchange channel arranged from top to bottom. The first cooler 32 is connected to the first sensible cold storage unit 31, and uses the ambient temperature to ensure that the methanol reaches a normal temperature state. The first normal temperature methanol tank 33 stores normal temperature methanol. Methanol, as a medium, can absorb and store cold energy. The first sensible cold recycling unit 34 includes the fourth heat exchange channel and the fifth heat exchange channel for recovering and reusing cold energy. The first low-temperature methanol tank 35 stores low-temperature methanol and provides a low-temperature heat source for the system. Among them, the gas outlet of the gas-liquid separator 8 is connected to the inlet of the compressor 2 through the first heat exchange channel to ensure that the gaseous carbon dioxide can directly enter the compressor 2 for compression. The outlet of the compressor 2 is connected to the inlet of the gas-liquid separator 8 through the second heat exchange channel to form a cycle, so that the heat generated by the gas during the compression process can be effectively managed and utilized. The discharge storage tank 4 is connected to the power generation device 5 through the fifth heat exchange channel, and the liquid carbon dioxide is heated and gasified during the discharge process, and then converted into electrical energy through the power generation device 5. The third heat exchange channel, the first cooler 32, the first normal temperature methanol tank 33, the fourth heat exchange channel and the first low temperature methanol tank 35 are connected in sequence to form a circulation loop for the storage and reuse of cold energy.

[0036] According to one embodiment of the present utility model, there are two compressors 2, namely, a first compressor 21 and a second compressor 22; further comprising a heating device 9, the heating device 9 comprising a first heat exchanger 91, a second heat exchanger 92, a third heat exchanger 93, a fourth heat exchanger 94, a hot water tank 95, a normal temperature water tank 96 and a second cooler 97; the first heat exchanger 91 has a sixth heat exchange channel and a seventh heat exchange channel; the first heat exchanger 91 is connected to the first compressor 21; the second heat exchanger 92 has an eighth heat exchange channel and a ninth heat exchange channel; the second heat exchanger 92 is connected to the second compressor 22; the third heat exchanger 93 has a tenth heat exchange channel and an eleventh heat exchange channel; the fourth heat exchanger 94 has a twelfth heat exchange channel and a tenth heat exchange channel; Three heat exchange channels; the air outlet of the gas-liquid separator 8 is connected to the inlet of the first compressor 21; the first compressor 21, the sixth heat exchange channel, the second compressor 22, the eighth heat exchange channel and the second heat exchange channel are connected in sequence; the inlet of the ninth heat exchanger channel and the inlet of the seventh heat exchanger channel are respectively connected to the outlet of the normal temperature water tank 96, and the outlet of the ninth heat exchanger channel and the outlet of the seventh heat exchanger channel are respectively connected to the inlet of the hot water tank 95; the outlet of the hot water tank 95 is connected to the inlet of the second cooler 97 through the tenth heat exchange channel and the twelfth heat exchange channel respectively; the outlet of the second cooler 97 is connected to the inlet of the normal temperature water tank 96; the discharge storage tank 4, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel and the power generation device 5 are connected in sequence.

[0037] In specific implementation, the system is equipped with two compressors, namely the first compressor 21 and the second compressor 22, each of which is connected to a heat exchanger to transfer compression heat. The heating device 9 is composed of a first heat exchanger 91, a second heat exchanger 92, a third heat exchanger 93, a fourth heat exchanger 94, a hot water tank 95, a normal temperature water tank 96 and a second cooler 97. The first heat exchanger 91 is connected to the first compressor 21 through the sixth and seventh heat exchange channels, and the second heat exchanger 92 is connected to the second compressor 22 through the eighth and ninth heat exchange channels. This configuration allows the heat generated during the compression process to be effectively transferred and utilized. The gas outlet of the gas-liquid separator 8 is directly connected to the inlet of the first compressor 21, ensuring the continuous flow and compression of the carbon dioxide gas. The first compressor 21, the sixth heat exchange channel, the second compressor 22, the eighth heat exchange channel and the second heat exchange channel are connected in sequence to form an efficient compression and heat exchange process. The inlets of the ninth and seventh heat exchanger channels are connected to the outlet of the normal temperature water tank 96, and their outlets are connected to the inlet of the hot water tank 95, forming a closed-loop heat exchange system. The outlet of the hot water tank 95 is connected to the inlet of the second cooler 97 through the tenth and twelfth heat exchange channels, and the outlet of the second cooler 97 returns to the inlet of the normal temperature water tank 96, completing the cooling cycle. The discharge storage tank 4 is connected to the power generation device 5 in sequence through the fifth heat exchange channel, the thirteenth heat exchange channel and the eleventh heat exchange channel, ensuring that the liquid carbon dioxide can be efficiently heated, gasified and converted into electrical energy during the discharge process.

[0038] According to one embodiment of the present utility model, the second liquefaction device 6 includes a second sensible cold storage unit 61, a second low-temperature methanol tank 62, a second sensible cold recycling unit 63, a third cooler 64 and a second normal temperature methanol tank 65; the second sensible cold storage unit 61 has a fourteenth heat exchange channel and a fifteenth heat exchange channel; the second sensible cold recycling unit 63 has a sixteenth heat exchange channel and a seventeenth heat exchange channel; the charging storage tank 1, the fourteenth heat exchange channel and the first compressor 21 are connected in sequence; the fifteenth heat exchange channel, the second low-temperature methanol tank 62, the sixteenth heat exchange channel, the third cooler 64 and the second normal temperature methanol tank 65 are connected in sequence; the discharge storage tank 4, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device 5, the seventeenth heat exchange channel and the charging storage tank 1 are connected in sequence.

[0039] In specific implementation, the second apparent cold storage unit 61 is equipped with the fourteenth and fifteenth heat exchange channels, which are responsible for efficiently transferring cold energy during the storage process. The second apparent cold recycling unit 63 realizes the recovery and reuse of cold energy in the system through the sixteenth and seventeenth heat exchange channels. The charging storage tank 1 is connected to the first compressor 21 through the fourteenth heat exchange channel, ensuring the continuous flow and compression of liquid carbon dioxide during the charging process. The second low-temperature methanol tank 62 and the second normal temperature methanol tank 65 are connected to the third cooler 64 in sequence through the fifteenth, sixteenth and eleventh heat exchange channels, forming a closed-loop cooling cycle to effectively manage and distribute the cold energy in the system. The discharge storage tank 4 is connected to the power generation device 5 through the fifth, thirteenth and eleventh heat exchange channels, realizing the efficient heating and gasification of liquid carbon dioxide during the discharge process, thereby promoting the power generation device to generate electricity. Through the seventeenth heat exchange channel, the gaseous carbon dioxide finally returns to the charging storage tank 1, completing the energy conversion cycle and preparing for the next charge and discharge cycle.

[0040] According to one embodiment of the utility model, the power generation device 5 includes a first expander 51, a second expander 52 and a generator 53; the first expander 51 and the second expander 52 are connected to the generator 53; the discharge tank 4, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander 51, the eleventh heat exchange channel, the second expander 52, the seventeenth heat exchange channel and the inlet of the charging tank 1 are connected in sequence.

[0041] In the specific implementation, in the present liquid carbon dioxide energy storage system, the power generation device 5 is composed of two key components: a first expander 51 and a second expander 52, which are connected to a generator 53. This configuration allows the system to drive the expander through the gasification and expansion of liquid carbon dioxide during the discharge process, thereby enabling the generator to generate electrical energy. Specifically, the liquid carbon dioxide in the discharge tank 4 is first heated to an appropriate temperature and pressure through the fifth heat exchange channel and the thirteenth heat exchange channel. Subsequently, the heated liquid carbon dioxide enters the first expander 51, where it rapidly expands and is converted into mechanical energy. The first expander 51 is connected to the second expander 52, so that the gaseous carbon dioxide can continue to expand in the second expander, further improving the energy conversion efficiency. The pressure and temperature of the gaseous carbon dioxide after the two-stage expander are further reduced, and then through the seventeenth heat exchange channel, the waste heat of the gaseous carbon dioxide is recycled to improve the overall thermal efficiency of the system. Finally, the gaseous carbon dioxide returns to the charging tank 1, where it is re-liquefied and ready for the next charge and discharge cycle. Through this design, the power generation device can not only effectively convert the internal energy of liquid carbon dioxide into electrical energy, but also improve the energy conversion efficiency and economy of the entire energy storage system through multi-stage expansion and waste heat recovery mechanisms. The system is compact and efficient, and can achieve effective storage and utilization of renewable energy, with good application prospects.

[0042] According to one embodiment of the utility model, it also includes a second throttle valve 10 and a phase-change cold storage heat exchanger 11; the inlet of the second throttle valve 10 is connected to the inlet of the charging tank 1; the phase-change cold storage heat exchanger 11 has a first phase-change cold storage heat exchange channel and a second phase-change cold storage heat exchange channel; the outlet of the charging tank 1, the second throttle valve 10, the first phase-change cold storage heat exchange channel, the fourteenth heat exchange channel and the inlet of the first compressor 21 are connected in sequence; the discharge tank 4, the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device 5, the seventeenth heat exchange channel, the second phase-change cold storage heat exchange channel and the inlet of the charging tank 1 are connected in sequence.

[0043] In specific implementation, by using the phase-change cold storage heat exchanger 11, the system can more effectively store and utilize the cold energy released in the process of liquefying carbon dioxide, thereby improving the overall energy efficiency of the system. Overall performance improvement of the system: Through these new components and improved connection methods, the liquid carbon dioxide energy storage system has been significantly improved in terms of energy storage density, cycle efficiency and adaptability.

[0044] According to one embodiment of the utility model, it also includes a cryogenic pump 12 and a fourth cooler 13, and the discharge storage tank 4, the cryogenic pump 12, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expansion machine 51, the eleventh heat exchange channel, the second expansion machine 52, the fourth cooler 13, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging storage tank 1 are connected in sequence.

[0045] In specific implementation, the cryopump 12 is used to increase the pressure of the liquid carbon dioxide to ensure its effective flow in the system; the fourth cooler 13 is used to cool the medium in the system, such as liquid carbon dioxide, to facilitate liquefaction. The position of the cryopump 12: The cryopump 12 is placed between the discharge tank 4 and the fifth heat exchange channel to ensure that the liquid carbon dioxide can be effectively raised to the required pressure during the discharge process. The connection of the fourth cooler 13: The fourth cooler 13 is connected to the second expander 52 and the seventeenth heat exchange channel, which helps to cool the liquid carbon dioxide after gasification and expansion, and recover and reuse part of the energy. Complete circulation loop: The discharge tank 4, the cryopump 12, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander 51, the eleventh heat exchange channel, the second expander 52, the fourth cooler 13, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging tank 1 are connected in sequence to form a closed-loop system, allowing the system to efficiently manage and recycle energy during the discharge and charging process. Improve system efficiency: By adding the cryopump 12 and the fourth cooler 13, the system has been strengthened in terms of the delivery and cooling of liquid carbon dioxide, which helps to improve the efficiency and performance of the entire energy storage system. Optimized energy management: The introduction of the cryopump 12 and the fourth cooler 13 enables the system to more finely control the state of liquid carbon dioxide during the energy conversion process, optimizing the storage and release of energy.

[0046] According to one embodiment of the utility model, it also includes a cryogenic pump 12, and the discharge storage tank 4, the cryogenic pump 12, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expansion machine 51, the eleventh heat exchange channel, the second expansion machine 52, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging storage tank 1 are connected in sequence.

[0047] According to one embodiment of the utility model, it also includes a fourth cooler 13, and the discharge tank 4, the cryogenic pump 12, the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander 51, the eleventh heat exchange channel, the second expander 52, the fourth cooler 13, the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging tank 1 are connected in sequence.

[0048] An overview of the working process, technical advantages and key points of the carbon dioxide energy storage system of this utility model:

[0049] 1. Working process:

[0050] Charging process: liquid carbon dioxide is throttled through the second throttle valve 10 and releases cold energy, gaseous carbon dioxide is compressed to reach a supercritical state, the compression heat is absorbed by the pressurized water and stored in the hot water tank 95, and the gaseous carbon dioxide close to room temperature is cooled and liquefied in the first sensible cold storage unit 31, and expanded to the energy storage pressure through the first throttle valve 7 and stored in the discharge storage tank 4.

[0051] Discharge process: Liquid carbon dioxide is raised to the energy release pressure in the discharge storage tank 4, and is reheated by the second sensible cooling recovery unit 62, and then heated by high-temperature hot water, and expands to drive the turbine to generate electricity. Finally, the gaseous carbon dioxide is cooled by the environment and liquefied and stored again.

[0052] 2. Technical advantages:

[0053] 1. Achieved higher energy density by storing carbon dioxide in a low-pressure liquid state.

[0054] 2. Improve cycle efficiency, usually higher than traditional compressed air energy storage systems.

[0055] 3. The system design is compact, reducing floor space and infrastructure costs.

[0056] 4. Make full use of the advantages of liquid carbon dioxide energy storage system and Linde's circulating liquefied cold storage unit to improve energy density, realize grid frequency regulation, peak shaving and valley filling, and improve overall efficiency.

[0057] 5. The system is highly adaptable, not restricted by geographical conditions, and can be deployed in a variety of environments.

[0058] 3. Key points of the technical solution:

[0059] 1. A high-pressure side liquid carbon dioxide energy storage process based on gas throttling liquefaction was developed to achieve low-pressure liquid storage.

[0060] 2. The system changes from high-pressure storage to low-pressure liquid storage, avoiding the use of high-pressure storage tanks, improving energy utilization and saving costs.

[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the utility model embodiment. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A liquid carbon dioxide energy storage system, characterized in that: It comprises a charging storage tank (1), at least one compressor (2), a first liquefaction device (3), a discharge storage tank (4), a power generation device (5) and a second liquefaction device (6) which are connected in sequence to form a circulation loop; The charging storage tank (1) is capable of storing low-pressure liquid carbon dioxide; The first liquefaction device (3) is capable of liquefying the carbon dioxide; The discharge storage tank (4) is capable of storing the carbon dioxide in a low-pressure liquid state; The second liquefaction device (6) is capable of liquefying the carbon dioxide.

2. The liquid carbon dioxide energy storage system according to claim 1, characterized in that: It also includes a first throttle valve (7) and a gas-liquid separator (8); One end of the first throttle valve (7) is connected to the first liquefaction device (3), and the other end of the first throttle valve (7) is connected to the inlet of the gas-liquid separator (8); The gas outlet of the gas-liquid separator (8) is connected to the inlet of the compressor (2); The liquid outlet of the gas-liquid separator (8) is connected to the inlet of the discharge storage tank (4).

3. The liquid carbon dioxide energy storage system according to claim 2, characterized in that: The first liquefaction device (3) comprises a first sensible cold storage unit (31), a first cooler (32), a first normal temperature methanol tank (33), a first sensible cold recycling unit (34) and a first low temperature methanol tank (35); The first sensible cold storage unit (31) has a first heat exchange channel, a second heat exchange channel and a third heat exchange channel; the gas outlet of the gas-liquid separator (8) is connected to the inlet of the compressor (2) through the first heat exchange channel; the outlet of the compressor (2), the second heat exchange channel and the inlet of the gas-liquid separator (8) are connected in sequence; The first sensible cooling recycling unit (34) has a fourth heat exchange channel and a fifth heat exchange channel; The discharge storage tank (4) is connected to the power generation device (5) through the fifth heat exchange channel; The third heat exchange channel, the first cooler (32), the first normal temperature methanol tank (33), the fourth heat exchange channel and the first low temperature methanol tank (35) are connected in sequence to form a circulation loop.

4. The liquid carbon dioxide energy storage system according to claim 3, characterized in that: There are two compressors (2), namely a first compressor (21) and a second compressor (22); The invention also comprises a heating device (9), wherein the heating device (9) comprises a first heat exchanger (91), a second heat exchanger (92), a third heat exchanger (93), a fourth heat exchanger (94), a hot water tank (95), a normal temperature water tank (96) and a second cooler (97); the first heat exchanger (91) has a sixth heat exchange channel and a seventh heat exchange channel; the first heat exchanger (91) is connected to the first compressor (21); The second heat exchanger (92) has an eighth heat exchange channel and a ninth heat exchange channel; the second heat exchanger (92) is connected to the second compressor (22); The third heat exchanger (93) has a tenth heat exchange channel and an eleventh heat exchange channel; The fourth heat exchanger (94) has a twelfth heat exchange channel and a thirteenth heat exchange channel; The gas outlet of the gas-liquid separator (8) is connected to the inlet of the first compressor (21); The first compressor (21), the sixth heat exchange channel, the second compressor (22), the eighth heat exchange channel and the second heat exchange channel are connected in sequence; The inlet of the ninth heat exchanger channel and the inlet of the seventh heat exchanger channel are respectively connected to the outlet of the normal temperature water tank (96), and the outlet of the ninth heat exchanger channel and the outlet of the seventh heat exchanger channel are respectively connected to the inlet of the hot water tank (95); The outlet of the hot water tank (95) is connected to the inlet of the second cooler (97) through the tenth heat exchange channel and the twelfth heat exchange channel respectively; The outlet of the second cooler (97) is connected to the inlet of the normal temperature water tank (96); The discharge storage tank (4), the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel and the power generation device (5) are connected in sequence.

5. The liquid carbon dioxide energy storage system according to claim 4, characterized in that: The second liquefaction device (6) comprises a second sensible cold storage unit (61), a second low-temperature methanol tank (62), a second sensible cold recycling unit (63), a third cooler (64) and a second normal temperature methanol tank (65); The second cold storage unit (61) has a fourteenth heat exchange channel and a fifteenth heat exchange channel; The second sensible cold recycling unit (63) has a sixteenth heat exchange channel and a seventeenth heat exchange channel; The charging storage tank (1), the fourteenth heat exchange channel and the first compressor (21) are connected in sequence; The fifteenth heat exchange channel, the second low-temperature methanol tank (62), the sixteenth heat exchange channel, the third cooler (64) and the second normal-temperature methanol tank (65) are connected in sequence; The discharge storage tank (4), the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device (5), the seventeenth heat exchange channel and the charge storage tank (1) are connected in sequence.

6. The liquid carbon dioxide energy storage system according to claim 5, characterized in that: The power generation device (5) comprises a first expander (51), a second expander (52) and a generator (53); The first expander (51) and the second expander (52) are connected to the generator (53); The discharge storage tank (4), the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander (51), the eleventh heat exchange channel, the second expander (52), the seventeenth heat exchange channel and the inlet of the charge storage tank (1) are connected in sequence.

7. The liquid carbon dioxide energy storage system according to claim 6, characterized in that: It also includes a second throttle valve (10) and a phase-change cold storage heat exchanger (11); The inlet of the second throttle valve (10) is connected to the inlet of the charging tank (1); The phase-change cold storage heat exchanger (11) comprises a first phase-change cold storage heat exchange channel and a second phase-change cold storage heat exchange channel; The outlet of the charging storage tank (1), the second throttle valve (10), the first phase-change cold storage heat exchange channel, the fourteenth heat exchange channel and the inlet of the first compressor (21) are connected in sequence; The discharge storage tank (4), the fifth heat exchange channel, the thirteenth heat exchange channel, the eleventh heat exchange channel, the power generation device (5), the seventeenth heat exchange channel, the second phase-change cold storage heat exchange channel and the inlet of the charging storage tank (1) are connected in sequence.

8. The liquid carbon dioxide energy storage system according to claim 7, characterized in that: The discharge storage tank (4), the cryogenic pump (12), the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander (51), the eleventh heat exchange channel, the second expander (52), the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charging storage tank (1) are connected in sequence.

9. The liquid carbon dioxide energy storage system according to claim 8, characterized in that: The device further comprises a fourth cooler (13), wherein the discharge storage tank (4), the cryogenic pump (12), the fifth heat exchange channel, the thirteenth heat exchange channel, the first expander (51), the eleventh heat exchange channel, the second expander (52), the fourth cooler (13), the seventeenth heat exchange channel, the second phase change cold storage heat exchange channel and the inlet of the charge storage tank (1) are connected in sequence.

10. The liquid carbon dioxide energy storage system according to any one of claims 1 to 9, characterized in that: The compressor (2) can be supplied with electrical energy by discarding electricity.

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