Carbon dioxide energy storage system capable of recycling heat

Abstract

The invention discloses a carbon dioxide energy storage system capable of recycling heat, which is characterized in that a heat regenerator is added in the carbon dioxide energy storage system, a first heat exchange passage and a second heat exchange passage are arranged in the heat regenerator, the first heat exchange passage is connected in series in a pipeline of a second heat exchange assembly, and the second heat exchange passage is connected in series between an expander and a first heat exchange assembly; and the gaseous carbon dioxide in the first heat exchange passage and the second heat exchange passage in the energy release state is subjected to heat exchange, the temperature of the gaseous carbon dioxide output by the expander is reduced, the temperature of the gaseous carbon dioxide in the second heat exchange assembly is increased, and therefore gradient utilization of energy is achieved, and the overall efficiency of the carbon dioxide energy storage system is improved. Meanwhile, the carbon dioxide is stored in a liquid form, so that the occupied area of the system is reduced; in addition, the phase change material is added into the heat exchanger, so that carbon dioxide flowing through the heat exchanger can be cooled and liquefied in the heat exchanger, and additional devices do not need to be added.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage, and in particular relates to a carbon dioxide energy storage system for heat recovery. Background Art

[0002] In the context of rapid development of new energy, new energy storage has become one of the key links in building a new power system. Storing energy through the liquefaction and vaporization of carbon dioxide can effectively solve the problem of power shortage during peak hours of electricity consumption. At the same time, the conversion efficiency of carbon dioxide energy storage technology is relatively high, and it can retain more energy in the process of converting electrical energy into liquid carbon dioxide, thereby improving the overall energy utilization efficiency. In addition, carbon dioxide has high specific heat capacity, good heat transfer performance, lower parasitic energy consumption, and higher system efficiency. Therefore, liquid carbon dioxide energy storage has the advantages of ultra-long time, large scale, high flexibility, high efficiency, and high energy storage density, and has more development prospects.

[0003] However, the liquid carbon dioxide energy storage system requires a large amount of cold capacity when liquefying gaseous carbon dioxide, or achieves the liquefaction of carbon dioxide by losing pressure; at the same time, directly liquefying gaseous carbon dioxide also causes heat loss. Summary of the invention

[0004] The object of the present invention is to provide a carbon dioxide energy storage system with heat recovery.

[0005] In a first aspect, the present invention provides a carbon dioxide energy storage system for heat recycling, which comprises a regenerator and a low-pressure liquid storage module, a cold storage component, a compressor, a heat storage component, a high-pressure liquid storage module, a heat release component, an expander and a cold release component which are sequentially connected to form a circulation loop; a first heat exchange path and a second heat exchange path capable of heat exchange are provided in the regenerator; the first heat exchange path in the regenerator is connected in series to a pipeline in the heat release component; the second heat exchange path in the regenerator is connected in series between the expander and the cold release component; During the energy release process, the liquid carbon dioxide enters the heat release component and is heated in the first stage before being input into the first heat exchange path of the regenerator; the liquid carbon dioxide output from the first heat exchange path enters the heat release component again for heating and gasification; the gaseous carbon dioxide output from the heat release component enters the expander for expansion and decompression, and causes the expander to perform external work; the gaseous carbon dioxide output from the expander is input into the second heat exchange path of the regenerator; the gaseous carbon dioxide output from the second heat exchange path enters the cold release component; Since the temperature of the gaseous carbon dioxide in the first heat exchange path input from the heat release component to the regenerator must be lower than that of the gaseous carbon dioxide in the first heat exchange path input from the expansion machine to the regenerator; therefore, part of the heat of the gaseous carbon dioxide in the first heat exchange path is exchanged to the gaseous carbon dioxide in the second heat exchange path; thereby reducing the temperature of the gaseous carbon dioxide input to the cold release component and increasing the temperature of the gaseous carbon dioxide in the heat release component.

[0006] Preferably, a throttle valve is connected in series between the low-pressure liquid storage module and the cold storage component; during the energy storage process, the flow cross-sectional area of ​​the liquid carbon dioxide output by the low-pressure liquid storage module is reduced when passing through the throttle valve and is converted into gas-liquid two-phase carbon dioxide; a first on-off valve is connected in series between the low-pressure liquid storage module and the cold release component.

[0007] Preferably, the cold storage assembly includes a primary cold storage device and a secondary cold storage device connected in series; the heat storage assembly includes a primary heat storage device and a secondary heat storage device connected in series; the heat release assembly includes a primary heat release device and a secondary heat release device connected in series; the cold release assembly includes a primary cold release device and a secondary cold release device connected in series; the first heat exchange path in the heat regenerator is connected in series between the primary heat release device and the secondary heat release device.

[0008] Preferably, a heat storage tank and a cold storage tank are connected in parallel between the primary cold storage device and the primary cold release device, between the secondary cold storage device and the secondary cold release device, between the primary heat storage device and the primary heat release device, and between the secondary heat storage device and the secondary heat release device; The cold energy released by the gasification of carbon dioxide in the energy storage state is stored in the cold storage tank by means of heat exchange between the primary cold storage device and the secondary cold storage device and the heat exchange medium, and in the energy release state, the cold energy is supplied to the liquefied carbon dioxide by means of heat exchange between the primary cold release device and the secondary cold release device and the heat exchange medium; The heat released by the liquefaction of carbon dioxide in the energy storage state is stored in the heat storage tank by means of heat exchange between the primary heat storage device and the secondary heat storage device and the heat exchange medium, and in the energy release state, the heat is supplied to the gasified carbon dioxide by means of heat exchange between the primary heat release device and the secondary heat release device and the heat exchange medium.

[0009] In a second aspect, the present invention provides a carbon dioxide energy storage system for heat recycling, which includes a low-pressure liquid storage module, a first heat exchange component, a compressor, a second heat exchange component, a high-pressure liquid storage module, a regenerator and an expander; the first heat exchange component and the second heat exchange component each include one or a plurality of phase change heat exchangers connected in series; the regenerator is provided with a first heat exchange passage and a second heat exchange passage capable of heat exchange; the first heat exchange passage in the regenerator is connected in series with a pipeline in the second heat exchange component; the low-pressure liquid storage module is connected to one end of the first heat exchange component; two branches are connected in parallel between the other end of the first heat exchange component and one end of the second heat exchange component; a compressor is provided on the first branch; a second heat exchange passage of the regenerator and an expander connected in series are provided on the first branch; the other end of the second heat exchange component is connected to the high-pressure liquid storage module; during operation, the energy storage system switches between an energy storage state and an energy release state; In the energy storage state, the fourth on-off valve provided in the pipeline in the second heat exchange component is opened, and the fourth on-off valve provided in the first heat exchange passage is closed; the liquid carbon dioxide in the low-pressure liquid storage module is stored in the high-pressure liquid storage module through the processes of gasification, compressor work pressurization, and liquefaction in sequence; In the energy release state, the fourth on-off valve provided in the pipeline in the second heat exchange component is closed, and the fourth on-off valve provided in the first heat exchange path is opened; the liquid carbon dioxide in the high-pressure liquid storage module is sequentially gasified, expanded and depressurized in the expander to release energy, and liquefied and stored in the low-pressure liquid storage module; since the temperature of the gaseous carbon dioxide in the first heat exchange path input from the second heat exchange component to the regenerator must be lower than the gaseous carbon dioxide in the second heat exchange path input from the expander to the regenerator; therefore, part of the heat of the gaseous carbon dioxide in the second heat exchange path is exchanged to the gaseous carbon dioxide in the first heat exchange path; so that the temperature of the gaseous carbon dioxide input to the first heat exchange component is reduced, and the temperature of the carbon dioxide in the pipeline of the second heat exchange component is increased.

[0010] Preferably, a throttle valve and a first on-off valve are connected in parallel between the low-pressure liquid storage module and the first heat exchange component; during the energy storage process, the throttle valve is opened and the first on-off valve is closed, and the flow cross-sectional area of ​​the liquid carbon dioxide output by the low-pressure liquid storage module is reduced when passing through the throttle valve and is converted into gas-liquid two-phase carbon dioxide; during the energy release process, the throttle valve is closed and the first on-off valve is opened.

[0011] Preferably, the first heat exchange component includes one or multiple cold storage and release components connected in sequence; the second heat exchange component includes one or multiple heat storage and release components connected in sequence.

[0012] Preferably, a second on-off valve is provided between the compressor and the first heat exchange component and the second heat exchange component; a third on-off valve is provided between the expander and the first heat exchange component and the second heat exchange component; in the energy storage state, the second on-off valve is opened and the third on-off valve is closed; in the energy release state, the second on-off valve is closed and the third on-off valve is opened.

[0013] Preferably, the phase change temperature of the phase change material in the first heat exchange component increases successively along the direction from the energy storage passage to the energy release passage; each phase change heat exchanger gradually absorbs the cold released by the gasification of carbon dioxide in the energy storage state, and gradually provides the cold required for liquefaction to the carbon dioxide in the energy release state; the phase change temperature of the phase change material in the second heat exchange component decreases successively along the direction from the energy storage passage to the energy release passage; each phase change heat exchanger gradually absorbs the heat released by the liquefaction of carbon dioxide in the energy storage state, and gradually provides the heat required for gasification to the carbon dioxide in the energy release state.

[0014] Preferably, in the energy storage state, the liquid carbon dioxide output by the low-pressure liquid storage module is converted into gaseous carbon dioxide through the first heat exchange component, and the released cold is stored by the first heat exchange component; the compressor increases the pressure of the gaseous carbon dioxide; the gaseous carbon dioxide is converted into liquid carbon dioxide in the second heat exchange component and input into the high-pressure liquid storage module, and the released heat is stored by the second heat exchange component; In the energy release state, the liquid carbon dioxide output by the high-pressure liquid storage module is converted into gaseous carbon dioxide through the second heat exchange component, and the released cold is stored by the second heat exchange component; the gaseous carbon dioxide expands in the expander to release energy; the gaseous carbon dioxide is converted into liquid carbon dioxide in the first heat exchange component and input into the low-pressure liquid storage module, and the released heat is stored by the second heat exchange component.

[0015] The present invention has the following beneficial effects: 1. The present invention adds a regenerator to the carbon dioxide energy storage system, and exchanges heat between the gaseous carbon dioxide output by the expander and the gaseous carbon dioxide in the second heat exchange component through the regenerator, thereby reducing the temperature of the gaseous carbon dioxide output by the expander and increasing the temperature of the gaseous carbon dioxide in the second heat exchange component, thereby realizing the cascade utilization of energy and improving the overall efficiency of the carbon dioxide energy storage system.

[0016] 2. The carbon dioxide in the present invention is stored in liquid form, which reduces the system footprint; at the same time, the present invention adds phase change material in the heat exchanger, so that the carbon dioxide flowing through the heat exchanger can be cooled and liquefied in the heat exchanger without adding additional devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the system structure of Example 1 of the present invention.

[0018] Figure 2 Schematic diagram of the system structure in the energy storage state of Example 2 of the present invention.

[0019] Figure 3 Schematic diagram of the system structure in the energy release state of Example 3 of the present invention.

[0020] Figure numerals: 1. low-pressure liquid storage module; 2. cold storage component; 3. compressor; 4. heat storage component; 5. high-pressure liquid storage module; 6. heat release component; 7. regenerator; 8. expander; 9. cold release component; 10. throttle valve; 11. first on-off valve; 12. second on-off valve; 13. third on-off valve; 14. fourth on-off valve; 15. first phase change heat exchanger; 16. second phase change heat exchanger; 17. third phase change heat exchanger; 18. fourth phase change heat exchanger. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings.

[0022] Example 1

[0023] like Figure 1 As shown, a heat recycling carbon dioxide energy storage system includes a regenerator 7 and a low-pressure liquid storage module 1, a cold storage component 2, a compressor 3, a heat storage component 4, a high-pressure liquid storage module 5, a heat release component 6, an expander 8 and a cold release component 9 which are sequentially connected to form a circulation loop. The cold storage component 2 is connected to the low-pressure liquid storage module 1 through a throttle valve 10, and the liquid carbon dioxide output by the low-pressure liquid storage module 1 is converted into gas-liquid two-phase carbon dioxide through the throttle valve 10. The cold storage component 2 includes a first-stage cold storage device and a second-stage cold storage device connected in series; the heat storage component 4 includes a first-stage heat storage device and a second-stage heat storage device connected in series; the heat release component 6 includes a first-stage heat release device and a second-stage heat release device connected in series; the cold release component 9 includes a first-stage cold release device and a second-stage cold release device connected in series; a heat storage tank and a cold storage tank are connected in parallel between the first-stage cold storage device and the first-stage cold release device, between the second-stage cold storage device and the second-stage cold release device, between the first-stage heat storage device and the first-stage heat release device, and between the second-stage heat storage device and the second-stage heat release device. The regenerator 7 is provided with a first heat exchange passage and a second heat exchange passage capable of heat exchange; the first heat exchange passage in the regenerator 7 is connected in series between the primary heat release device and the secondary heat release device; the second heat exchange passage in the regenerator 7 is connected in series between the expander 8 and the cold release component 9; during operation, the energy storage system switches between the energy storage state and the energy release state.

[0024] In the energy storage state, the liquid carbon dioxide in the low-pressure liquid storage module 1 passes through the opened throttle valve 10 under the action of pressure difference, and is converted into gas-liquid two-phase carbon dioxide under the action of throttling gasification, and enters the cold storage component 2; the first-stage cold storage device and the second-stage cold storage device respectively exchange heat with the carbon dioxide input into the cold storage component 2 through the heat exchange medium input from the corresponding heat storage tank, so that the gas-liquid two-phase carbon dioxide is gradually heated in the cold storage component 2, and the gaseous carbon dioxide is output, and the heat exchange medium is transported to the corresponding cold storage tank for storage. The compressor 3 consumes electric energy to pressurize the gaseous carbon dioxide output from the cold storage component 2, and then inputs it into the heat storage component 4. The first-stage heat storage device and the second-stage heat storage device respectively exchange heat with the carbon dioxide input into the heat storage component 4 through the heat exchange medium input from the corresponding cold storage tank, so that the gaseous carbon dioxide is gradually cooled in the heat storage component 4, and liquid carbon dioxide is obtained, and is transported to the high-pressure liquid storage module 5 for storage, and the heat exchange medium is transported to the corresponding heat storage tank for storage, completing energy storage.

[0025] In the energy release state, the liquid carbon dioxide in the high-pressure liquid storage module 5 is input into the secondary heat release device. The secondary heat release device exchanges heat with the carbon dioxide input into the secondary heat release device through the heat exchange medium input from the corresponding heat storage tank, increases the temperature of the carbon dioxide, and outputs gaseous carbon dioxide; the gaseous carbon dioxide output from the secondary heat release device is input into the primary heat release device through the first heat exchange path of the regenerator 7; the primary heat release device exchanges heat with the carbon dioxide input into the primary heat release device through the heat exchange medium input from the corresponding heat storage tank, further increasing the temperature of the carbon dioxide. The heated gaseous carbon dioxide in the primary heat release device is input into the expander 8, which does work to the outside through the expansion of the gaseous carbon dioxide and releases energy to complete the energy release. The gaseous carbon dioxide output from the expander 8 is input into the second heat exchange path, and exchanges heat with the carbon dioxide in the first heat exchange path, further increasing the temperature of the gaseous carbon dioxide input into the primary heat release device, reducing the temperature of the carbon dioxide output from the expander 8, and input into the cold release component 9. The first-stage cooling device and the second-stage cooling device respectively exchange heat with the carbon dioxide input into the cooling component 9 through the heat exchange medium input from the corresponding cooling tank, so that the gaseous carbon dioxide is gradually cooled in the cooling component 9, and liquid carbon dioxide is obtained and transported to the low-pressure liquid storage module 1 for storage through the first on-off valve 11, and the heat exchange medium is transported to the corresponding heat storage tank for storage.

[0026] Example 2

[0027] like Figure 2 and 3 As shown, a carbon dioxide energy storage system for heat recycling includes a regenerator 7 and a low-pressure liquid storage module 1, a first heat exchange component, a compression expansion module, a second heat exchange component and a high-pressure liquid storage module 5 connected in sequence. The low-pressure liquid storage module 1 is connected to the first heat exchange component through two independent valves and pipelines; the first heat exchange component includes a first phase change heat exchanger 15 and a second phase change heat exchanger 16 connected in series; the second heat exchange component includes a third phase change heat exchanger 17 and a fourth phase change heat exchanger 18 connected in series. The compression expansion module includes a compressor 3 and an expander 8 connected in parallel. Phase change materials are stored in the first phase change heat exchanger 15, the second phase change heat exchanger 16, the third phase change heat exchanger 17 and the fourth phase change heat exchanger 18. The first heat exchange path in the regenerator 7 is connected in series between the third phase change heat exchanger 17 and the fourth phase change heat exchanger 18; the second heat exchange path in the regenerator 7 is connected in series between the first heat exchange component and the expander 8; during operation, the energy storage system switches between the energy storage state and the energy release state. During operation, the energy storage system switches between an energy storage state and an energy release state.

[0028] In the energy storage state, the fourth on-off valve 14 provided in the pipeline of the second heat exchange component is opened, and the fourth on-off valve 14 provided in the first heat exchange passage is closed; the second on-off valve 12 provided between the compressor 3 and the first heat exchange component and the second heat exchange component is opened; the third on-off valve 13 provided between the expander 8 and the first heat exchange component and the second heat exchange component is closed; the liquid carbon dioxide in the low-pressure liquid storage module 1 passes through the opened throttle valve 10 under the action of the pressure difference, and is converted into gas-liquid two-phase carbon dioxide under the action of throttling gasification, and enters the first heat exchange component; the phase change materials stored in the first phase change heat exchanger 15 and the second phase change heat exchanger 16 exchange heat with carbon dioxide respectively, so that the gas-liquid two-phase carbon dioxide is gradually heated in the first heat exchange component to obtain gaseous carbon dioxide. The gaseous carbon dioxide output by the first heat exchange component is input into the compressor 3 through the second on-off valve 12; the compressor 3 consumes electric energy to pressurize the gaseous carbon dioxide output by the first heat exchange component, and then inputs it into the second heat exchange component through the second on-off valve 12. The phase change materials stored in the two heat exchangers in the second heat exchange component exchange heat with carbon dioxide respectively, so that the gaseous carbon dioxide is gradually cooled in the second heat exchange component, liquid carbon dioxide is obtained, and transported to the high-pressure liquid storage module 5 for storage, thereby completing energy storage.

[0029] In the energy release state, the fourth on-off valve 14 provided in the pipeline in the second heat exchange component is closed, and the fourth on-off valve 14 provided in the first heat exchange passage is opened; the second on-off valve 12 provided between the compressor 3 and the first heat exchange component and the second heat exchange component is closed; the third on-off valve 13 provided between the expander 8 and the first heat exchange component and the second heat exchange component is opened; the liquid carbon dioxide in the high-pressure liquid storage module 5 is input into the fourth phase change heat exchanger 18; the phase change material stored in the fourth phase change heat exchanger 18 exchanges heat with carbon dioxide, so that the liquid carbon dioxide is heated in the fourth phase change heat exchanger 18 and gaseous carbon dioxide is output. The gaseous carbon dioxide output by the fourth phase change heat exchanger 18 is input into the third phase change heat exchanger 17 through the first heat exchange passage; the phase change material stored in the third phase change heat exchanger 17 exchanges heat with carbon dioxide to further increase the temperature of carbon dioxide. The third phase change heat exchanger 17 is input into the expander 8 through the third on-off valve 13, and the expander 8 performs external work through the expansion of gaseous carbon dioxide and releases energy to complete the energy release. The expander 8 inputs the gaseous carbon dioxide into the second heat exchange path and exchanges heat with the carbon dioxide in the first heat exchange path, further increasing the temperature of the gaseous carbon dioxide input into the third phase change heat exchanger 17, reducing the temperature of the gaseous carbon dioxide output by the expander 8 and inputting it into the first heat exchange component through the third on-off valve 13. The phase change materials stored in the first phase change heat exchanger 15 and the second phase change heat exchanger 16 exchange heat with carbon dioxide respectively, so that the gaseous two-phase carbon dioxide is gradually cooled in the first heat exchange component, and liquid carbon dioxide is obtained, and is transported to the low-pressure liquid storage module 1 for storage through the first on-off valve 11.

Claims

1. A carbon dioxide energy storage system for heat recovery, characterized in that: The energy storage system comprises a regenerator (7) and a low-pressure liquid storage module (1), a cold storage component (2), a compressor (3), a heat storage component (4), a high-pressure liquid storage module (5), a heat release component (6), an expander (8) and a cold release component (9) which are sequentially connected to form a circulation loop; a first heat exchange path and a second heat exchange path capable of performing heat exchange are provided in the regenerator (7); the first heat exchange path in the regenerator (7) is connected in series to a pipeline in the heat release component (6); the second heat exchange path in the regenerator (7) is connected in series between the expander (8) and the cold release component (9); during operation, the energy storage system switches between an energy storage state and an energy release state; During the energy release process, part of the heat of the gaseous carbon dioxide in the first heat exchange path is exchanged to the second heat exchange path, so that the temperature of the gaseous carbon dioxide input to the cold release component (9) decreases and the temperature of the gaseous carbon dioxide in the heat release component (6) increases.

2. A carbon dioxide energy storage system for heat recovery according to claim 1, characterized in that: A throttle valve (10) is connected in series between the low-pressure liquid storage module (1) and the cold storage component (2); during the energy storage process, the liquid carbon dioxide output by the low-pressure liquid storage module (1) has a reduced flow cross-sectional area when passing through the throttle valve (10), and is converted into gas-liquid two-phase carbon dioxide; and a first on-off valve (11) is connected in series between the low-pressure liquid storage module (1) and the cold release component (9).

3. The carbon dioxide energy storage system for heat recovery according to claim 1 is characterized in that: The cold storage component (2) comprises a primary cold storage device and a secondary cold storage device connected in series; the heat storage component (4) comprises a primary heat storage device and a secondary heat storage device connected in series; the heat release component (6) comprises a primary heat release device and a secondary heat release device connected in series; the cold release component (9) comprises a primary cold release device and a secondary cold release device connected in series; and the first heat exchange path in the heat regenerator (7) is connected in series between the primary heat release device and the secondary heat release device.

4. The carbon dioxide energy storage system for heat recovery according to claim 1 is characterized in that: A heat storage tank and a cold storage tank are connected in parallel between the primary cold storage device and the primary cold release device, between the secondary cold storage device and the secondary cold release device, between the primary heat storage device and the primary heat release device, and between the secondary heat storage device and the secondary heat release device; The cold energy released by the gasification of carbon dioxide in the energy storage state is stored in the cold storage tank by means of heat exchange between the primary cold storage device and the secondary cold storage device and the heat exchange medium, and in the energy release state, the cold energy is supplied to the liquefied carbon dioxide by means of heat exchange between the primary cold release device and the secondary cold release device and the heat exchange medium; The heat released by the liquefaction of carbon dioxide in the energy storage state is stored in the heat storage tank by means of heat exchange between the primary heat storage device and the secondary heat storage device and the heat exchange medium, and in the energy release state, the heat is supplied to the gasified carbon dioxide by means of heat exchange between the primary heat release device and the secondary heat release device and the heat exchange medium.

5. A carbon dioxide energy storage system for heat recovery, characterized in that: The energy storage system comprises a low-pressure liquid storage module (1), a first heat exchange component, a compressor (3), a second heat exchange component, a high-pressure liquid storage module (5), a heat regenerator (7) and an expander (8); the first heat exchange component and the second heat exchange component each comprise one or a plurality of phase change heat exchangers connected in series; the heat regenerator (7) is provided with a first heat exchange passage and a second heat exchange passage capable of performing heat exchange; the first heat exchange passage in the heat regenerator (7) is connected in series with a pipeline in the second heat exchange component; the low-pressure liquid storage module (1) is connected to one end of the first heat exchange component; two branches are connected in parallel between the other end of the first heat exchange component and one end of the second heat exchange component; the first branch is provided with a compressor (3); the first branch is provided with a heat regenerator (7), a second heat exchange passage and an expander (8) connected in series; the other end of the second heat exchange component is connected to the high-pressure liquid storage module (5); during operation, the energy storage system switches between an energy storage state and an energy release state; In the energy storage state, the fourth on-off valve (14) provided in the pipeline in the second heat exchange component is opened, and the fourth on-off valve (14) provided in the first heat exchange path is closed; the liquid carbon dioxide in the low-pressure liquid storage module (1) is sequentially stored in the high-pressure liquid storage module (5) through the processes of gasification, pressurization by the compressor (3), and liquefaction; In the energy release state, the fourth on-off valve (14) provided in the pipeline of the second heat exchange component is closed, and the fourth on-off valve (14) provided in the first heat exchange path is opened; the liquid carbon dioxide in the high-pressure liquid storage module (5) is sequentially stored in the low-pressure liquid storage module (1) through the processes of gasification, expansion and pressure reduction in the expander (8) to release energy, and liquefaction; part of the heat of the gaseous carbon dioxide in the second heat exchange path is exchanged to the gaseous carbon dioxide in the first heat exchange path; thereby reducing the temperature of the gaseous carbon dioxide input into the first heat exchange component and increasing the temperature of the carbon dioxide in the pipeline of the second heat exchange component.

6. The carbon dioxide energy storage system for heat recovery according to claim 5, characterized in that: A throttle valve (10) and a first on-off valve (11) are provided in parallel between the low-pressure liquid storage module (1) and the first heat exchange component; during the energy storage process, the throttle valve (10) is opened and the first on-off valve (11) is closed; when the liquid carbon dioxide output by the low-pressure liquid storage module (1) passes through the throttle valve (10), the flow cross-sectional area is reduced and the liquid carbon dioxide is converted into gas-liquid two-phase carbon dioxide; during the energy release process, the throttle valve (10) is closed and the first on-off valve (11) is opened.

7. The carbon dioxide energy storage system for heat recovery according to claim 5, characterized in that: The first heat exchange component includes one or multiple cold storage and release components connected in sequence; the second heat exchange component includes one or multiple heat storage and release components connected in sequence.

8. The carbon dioxide energy storage system for heat recovery according to claim 5, characterized in that: A second on-off valve (12) is provided between the compressor (3) and the first heat exchange component and the second heat exchange component; a third on-off valve (13) is provided between the expander (8) and the first heat exchange component and the second heat exchange component; in the energy storage state, the second on-off valve (12) is opened and the third on-off valve (13) is closed; in the energy release state, the second on-off valve (12) is closed and the third on-off valve (13) is opened.

9. The carbon dioxide energy storage system for heat recovery according to claim 5, characterized in that: Along the direction from the energy storage passage to the energy release passage, the phase change temperature of the phase change material in the first heat exchange component increases successively; each phase change heat exchanger absorbs the cold released by the gasification of carbon dioxide step by step in the energy storage state, and provides the cold required for liquefaction to carbon dioxide step by step in the energy release state; along the direction from the energy storage passage to the energy release passage, the phase change temperature of the phase change material in the second heat exchange component decreases successively; each phase change heat exchanger absorbs the heat released by the liquefaction of carbon dioxide step by step in the energy storage state, and provides the heat required for gasification to carbon dioxide step by step in the energy release state.

10. The carbon dioxide energy storage system for heat recovery according to claim 5, characterized in that: In the energy storage state, the liquid carbon dioxide output by the low-pressure liquid storage module (1) is converted into gaseous carbon dioxide through the first heat exchange component, and the released cold energy is stored by the first heat exchange component; the compressor (3) increases the pressure of the gaseous carbon dioxide; the gaseous carbon dioxide is converted into liquid carbon dioxide in the second heat exchange component and input into the high-pressure liquid storage module (5), and the released heat energy is stored by the second heat exchange component; In the energy release state, the liquid carbon dioxide output by the high-pressure liquid storage module (5) is converted into gaseous carbon dioxide through the second heat exchange component, and the released cold energy is stored by the second heat exchange component; the gaseous carbon dioxide expands in the expander (8) to release energy; the gaseous carbon dioxide is converted into liquid carbon dioxide in the first heat exchange component and input into the low-pressure liquid storage module (1), and the released heat energy is stored by the second heat exchange component.

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