CN116388405B

CN116388405B - System and method for integrating carbon dioxide seal and energy storage power generation

Info

Publication number: CN116388405B
Application number: CN202310668425.9A
Authority: CN
Inventors: 郑开云; 周云; 朱智慧; 孙军歌; 徐振宇; 陶林; 池捷成
Original assignee: Henan Yellow River Energy Innovation Center Co ltd; Shijia Toubo Henan Energy Technology Co ltd
Current assignee: Henan Yellow River Energy Innovation Center Co ltd; Shijia Toubo Henan Energy Technology Co ltd
Priority date: 2023-06-07
Filing date: 2023-06-07
Publication date: 2023-08-29
Anticipated expiration: 2043-06-07
Also published as: CN116388405A

Abstract

The application provides a system and a method for integrating carbon dioxide sealing and energy storage power generation, wherein the system can receive carbon dioxide obtained from a carbon dioxide capturing device, can be used for energy storage power generation after filling, can store about 7 ten thousand tons of liquid carbon dioxide for a 10-square-capacity gas storage used for the system, and can fully charge and discharge the gas storage of the system, wherein the energy storage capacity is approximately 3 times of that of a conventional compressed air energy storage power station with the same gas storage capacity. The application integrates two purposes of carbon dioxide sealing and energy storage power generation, can seal and store carbon dioxide for more than 30 years, has the functions of low-grade waste heat utilization and cold supply, and has excellent comprehensive benefits.

Description

System and method for integrating carbon dioxide seal and energy storage power generation

Technical Field

The application relates to the technical field of carbon dioxide sealing and energy storage power generation, in particular to a system and a method for integrating carbon dioxide sealing and energy storage power generation.

Background

Carbon dioxide sequestration is to store carbon dioxide in a specific natural or artificial reservoir, and uses physical, chemical, biochemical and other methods to sequester carbon dioxide for a long period of time, which is the most critical condition for carbon dioxide capture and utilization and sequestration (CCUS) technology to achieve. Carbon dioxide geological sequestration technology is still in the research and demonstration stage, and has a considerable gap from commercial applications. The artificial container is flexible in sealing arrangement, is suitable for some specific scenes, but has high cost purely as a carbon dioxide sealing purpose, and is difficult to apply on a large scale.

The compressed gas energy storage technology is an electric power energy storage system capable of realizing large-capacity and long-time electric energy storage, and a gas working medium is used for a compressor, such as: air, carbon dioxide and the combination of the two are compressed to high pressure and stored to store redundant power, and when electricity is needed, the high pressure gas is released and expanded to do work to generate electricity. When the carbon dioxide working medium is adopted, the storage equipment of the compressed gas energy storage system has the function of sealing and storing carbon dioxide to a certain extent, and can simultaneously seal and store carbon dioxide in the service life period of the energy storage system for decades.

The CN115632488A discloses a cascade energy storage system and an energy storage method, wherein the cascade energy storage system has lower gas storage pressure and good safety, the volume of a gas storage is reduced by more than 80 percent compared with that of a normal pressure gas storage, and the volume of the gas storage is smaller than that of the high pressure gas storage under the gas storage pressure of more than 3 MPa; under the operation working condition of constant gas storage pressure, the compression and expansion processes of air and working media are operated under the constant working condition, no throttling loss is caused, the energy storage efficiency is higher, and the construction cost is controllable. However, the liquid working medium of the liquid storage tank is needed to be utilized and is gasified outside and then returned to the liquid storage tank to carry out maintenance pressure of the liquid storage tank, and in the energy release stage of the cascade energy storage system, the gas working medium output by the working medium expander unit always heats the liquid working medium and maintains the pressure of the liquid storage tank to be constant, but the system is complex, so that the whole energy consumption of the system is reduced, and the regulation and control of the system are not easy. In addition, CN115632488A only alleviates the problems of safety, high efficiency, low cost, constant pressure operation and the like of gas compression energy storage, and has weaker effect in carbon dioxide sealing, and the main reason is that carbon dioxide in the gas storage is stored in a gaseous state, the gaseous state density is small, and the total storage quality is small, so that the system and the process flow thereof need to be thoroughly changed, the storage state of the carbon dioxide is changed, and the large-scale carbon dioxide sealing capability is formed.

Therefore, the ultra-large volume high pressure reservoir configured in the existing compressed gas energy storage device only considers the energy storage purpose, is not combined with the carbon dioxide sealing and storing requirement, has single function, and does not realize the maximum utilization.

Disclosure of Invention

The present application aims to solve at least one of the technical problems in the related art to some extent.

To this end, the object of the present application is to propose a system and a method for integrating carbon dioxide sequestration with energy storage power generation, wherein the system for integrating carbon dioxide sequestration with energy storage power generation comprises two sequestration banks of liquid carbon dioxide: one is a large-volume normal-temperature high-pressure sealing warehouse, and the normal-temperature high-pressure sealing warehouse also has the function of storing compressed air; the other is a low temperature and low pressure enclosure of small volume, storing only liquid carbon dioxide. During the energy storage phase, the liquid carbon dioxide is stored in the low-pressure sealing warehouse, and the compressed air is stored in the high-pressure sealing warehouse, and during the energy release phase, the liquid carbon dioxide is stored in the high-pressure sealing warehouse, and the compressed air in the high-pressure sealing warehouse is discharged. Because the high-pressure sealing warehouse in the system has huge warehouse capacity, carbon dioxide is stored in liquid state, the quality of the sealing working medium is huge and is more than 10 times larger than the storage capacity of gaseous carbon dioxide, and the high-pressure sealing warehouse of the carbon dioxide in the system is shared with the compressed air energy storage warehouse for use, so that the construction cost is saved. In addition, the energy release stage of the system of the application carries out the intermittent pressure regulation on the low-pressure sealing warehouse in a stepwise manner, so that the pressure in the low-pressure sealing warehouse is stable or kept to be changed within a reasonable small range, and the system energy efficiency is improved while the composition and the control method of the system of the application are simplified.

In order to achieve the above object, the present application provides a system for integrating carbon dioxide seal and energy storage and power generation, comprising

A high pressure reservoir and a low pressure reservoir in communication; the high-pressure sealing warehouse comprises a high-pressure warehouse which is divided into an air cavity and a liquid cavity by an air bag; the air cavity and the liquid cavity are equal in pressure and the volume is adjusted through the scaling of the air bag; the air cavity is used for storing compressed air, and the liquid cavity and the low-pressure sealing warehouse are respectively used for storing liquid carbon dioxide with different temperatures;

the air compression energy release assembly is communicated with the air cavity and is used for introducing compressed air into the air cavity and releasing the compressed air;

the working medium compression energy release assembly comprises a working medium depressurization and cooling assembly and a working medium pressurization and heating assembly; the working medium depressurization and cooling assembly comprises a working medium compression unit and a throttle valve unit; the outlet of the liquid cavity, the throttle valve unit and the inlet of the low-pressure sealing warehouse are sequentially connected through a working medium cooling pipeline; the gas outlet of the low-pressure sealing warehouse, the working medium compression unit and the inlet of the throttle valve unit are sequentially connected through a working medium compression pipeline; the liquid outlet of the low-pressure sealing warehouse, the working medium boosting and heating assembly and the inlet of the liquid cavity are sequentially connected through a working medium heating pipeline; and

And the heat storage assembly is used for releasing heat or storing heat to the air compression energy release assembly and the working medium compression energy release assembly under different working conditions of the air compression energy release assembly and the working medium compression energy release assembly.

In some embodiments, the air compression energy release assembly comprises an air compression assembly, wherein the air compression assembly comprises an air compressor unit and an air heat exchanger unit, an outlet of the air compressor unit being connected to an inlet of the air cavity for air compression; the air heat exchanger unit is used for recovering heat in the compressed air discharged by the air compressor unit and transmitting the heat to the heat storage component, and the compressed air after heat exchange is input into the air cavity.

In some embodiments, the air compressor unit comprises a multi-stage series connected air compressor; the air heat exchanger unit comprises a plurality of stages of air heat exchangers, wherein the air compressors are in one-to-one correspondence with the air heat exchangers.

In some embodiments, the air compression energy release assembly further comprises an air expansion assembly, an inlet of the air expansion assembly is connected with an outlet of the air cavity for expanding compressed air to generate electricity; the air expansion assembly comprises an air expander unit and an air reheater unit, and compressed air in the air cavity enters the air expander unit to be expanded and generate electricity; the air reheater unit is used for heating the compressed air entering the air expander unit.

In some embodiments, the air expander unit comprises a multistage series of air expanders; the air reheater unit comprises a plurality of stages of air reheaters, wherein the air expanders are in one-to-one correspondence with the air reheaters.

In some embodiments, the working fluid depressurization and cooling assembly further comprises a working fluid heat exchanger unit; wherein the working medium compressor unit is used for compressing liquid carbon dioxide output by the low-pressure sealing warehouse; the working medium heat exchanger unit is used for recovering heat of working medium compressed gas discharged by the working medium compressor unit and transmitting the heat to the heat storage component; and the working medium compressed gas enters the throttle valve unit and is converted into liquid carbon dioxide and then is conveyed into the low-pressure sealing warehouse.

In some embodiments, the working fluid compressor unit comprises a multi-stage series connected working fluid compressor; the working medium heat exchanger unit comprises a plurality of stages of working medium heat exchangers, wherein the working medium compressors are in one-to-one correspondence with the working medium heat exchangers.

In some embodiments, the throttle valve unit comprises a plurality of stages of throttle valves connected in series and a gas flow separator between adjacent ones of the throttle valves; the gas outlet of the gas flow separator is connected with the working medium compression pipeline, and the gas outlet of the gas flow separator is connected with the downstream throttle valve.

In some embodiments, the working medium boosting and heating assembly comprises a liquid booster pump, a liquid preheater, a working medium expander unit and a cooler which are sequentially arranged on the working medium heating pipeline, wherein an inlet of the liquid booster pump is connected with a liquid outlet of the low-pressure sealing warehouse; the cooler is connected with an inlet of the liquid cavity; the working medium boosting and heating assembly further comprises a working medium reheater unit which is used for heating liquid carbon dioxide entering the working medium expander unit.

In some embodiments, the working medium boosting and heating assembly further comprises a back pressure pipeline; and the inlet and the outlet of the back pressure pipeline are respectively communicated with the working medium heating pipeline and the inlet of the low-pressure sealing warehouse.

In some embodiments, the working fluid expander unit comprises a plurality of stages of working fluid expanders connected in series, wherein the working fluid expander of the final stage is disposed on the back pressure line; the working medium reheater unit comprises a plurality of stages of working medium reheaters, wherein the working medium expansion machines are in one-to-one correspondence with the working medium reheaters.

In some embodiments, a plurality of heating channels are provided within the working medium reheater for absorbing waste heat from the heat storage assembly and external waste heat or waste heat.

In some embodiments, the heat storage assembly comprises a plurality of groups of high and low temperature tanks respectively connected with the air heat exchanger, the air reheater and the working medium reheater for storing heat from compressed air; and releasing heat to the compressed air and liquid carbon dioxide in the air reheater and the working medium reheater.

In some embodiments, each set of the high and low temperature tanks includes a hot tank and a cold tank that are paired for use; the low-temperature heat transfer medium in the cold tank absorbs heat in the compressed air and becomes high-temperature heat transfer medium to be stored in the hot tank; and the heat transfer medium in the hot tank releases heat to the compressed air and the liquid carbon dioxide in the air reheater and the working medium reheater to become low-temperature heat transfer medium, and the low-temperature heat transfer medium is stored in the cold tank.

In some embodiments, a method of operating an integrated carbon dioxide seal and energy storage power generation system is provided according to a second aspect of the application, utilizing the system described in any of the embodiments above for energy storage and power generation, comprising the steps of:

energy storage stage: the air cavity and the low-pressure sealing warehouse are both in a venting state in the initial stage, and the liquid cavity is filled with liquid carbon dioxide of at least 7 MPa; the energy storage stage comprises a liquid working medium transfer stage and an air compression energy storage stage which are carried out simultaneously;

The liquid working medium transfer phase is as follows: the liquid carbon dioxide is discharged from the liquid cavity, is gradually reduced in pressure and temperature to-50-5 ℃ and the corresponding pressure state of 0.7-4 MPa through the throttle valve, the liquid carbon dioxide after the temperature reduction and the pressure reduction is stored in the low-pressure sealing warehouse, the gas carbon dioxide generated in the period is compressed step by step through the working medium compressor, the working medium heat exchanger is used for cooling the working medium compressed gas until the working medium compressed gas is liquefied in the period, and the liquefied working medium compressed gas is returned to the inlet of the throttle valve until the liquid cavity is exhausted;

the air compression energy storage stage is as follows: starting an air compressor to compress air to the pressure of the liquid cavity, and then sending the air into the air cavity, and recovering air compression heat by using an air heat exchanger until the compressed air is normal temperature until the air cavity is full of compressed air;

the energy release stage comprises a liquid working medium energy release stage and a compressed air energy release stage which are carried out simultaneously; wherein the method comprises the steps of

The energy release stage of the liquid working medium is as follows: the liquid carbon dioxide is output from the low-pressure sealing warehouse and boosted to more than 15MPa by the liquid booster pump, and is introduced into the working medium expander to generate electricity after sequentially passing through the liquid preheater and the working medium reheater; the working medium pressure output by the working medium expander is reduced to the air cavity pressure, the working medium output by the working medium expander is respectively conveyed to the low-pressure sealing warehouse through a back pressure pipeline and is condensed by a cooler on the working medium heating pipeline and then conveyed to a liquid cavity until the liquid carbon dioxide in the low-pressure sealing warehouse is exhausted;

The compressed air energy release stage is as follows: and the compressed air output by the air cavity is heated by the air reheater and then expanded in the air expander to generate power until the air cavity is exhausted.

Additional aspects and advantages of the application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the application.

Drawings

The foregoing and/or additional aspects and advantages of the application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an integrated carbon dioxide seal and energy storage power generation system according to an embodiment of the present application;

FIG. 2 is a schematic diagram of an integrated carbon dioxide seal and energy storage power generation system according to an embodiment of the present application;

FIG. 3 is a schematic diagram of an integrated carbon dioxide seal and energy storage power generation system according to an embodiment of the present application;

FIG. 4 is a schematic diagram of an integrated carbon dioxide seal and energy storage power generation system according to an embodiment of the present application;

FIG. 5 is a flow chart of a method of operating an integrated carbon dioxide sequestration and storage power generation system in accordance with an embodiment of the present application;

100, high pressure enclosure; 101. a high pressure reservoir; 102. an air bag; 200. a low pressure seal bank;

1. An air compression assembly; 11. a first air compressor; 12. a second air compressor; 13. a first air heat exchanger; 14. a second air heat exchanger;

2. a working medium depressurization and cooling component; 21. a first working medium compressor; 22. a second working medium compressor; 23. a first working medium intercooler; 24. a second working medium intercooler; 25. a first throttle valve; 26. a second throttle valve; 27. a gas flow separator;

3. a heat storage assembly; 31. a first hot tank; 32. a first cooling tank; 33. a second hot tank; 34. a second cooling tank;

4. a working medium boosting and heating assembly; 41. a liquid booster pump; 42. a liquid preheater; 43. a first working medium expander; 44. a second working medium expander; 45. a third working medium expander; 46. a first working medium reheater; 47. a second working medium reheater; 48. a third working medium reheater; 49. a cooler;

5. an air expansion assembly; 51. a first air expander; 52. a second air expander; 53. a first air reheater; 54. a second air reheater;

a is a hot side outlet of the second air reheater, and is connected with an inlet corresponding to the third working medium reheater; b is an inlet of the first cooling tank and is connected with an outlet corresponding to the third working medium reheater; c is a hot side outlet of the first air reheater and is connected with an inlet corresponding to the third working medium reheater; d is an inlet of the second cooling tank and is connected with an outlet corresponding to the third working medium reheater.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the application. On the contrary, the embodiments of the application include all alternatives, modifications and equivalents as may be included within the spirit and scope of the appended claims.

Referring to fig. 1, in order to achieve the above-mentioned object, the present application provides a system for integrating carbon dioxide sealing and energy storage and power generation, which comprises a high-pressure sealing warehouse 100 and a low-pressure sealing warehouse 200 which are communicated, an air compression energy release assembly, a working medium compression energy release assembly and a heat storage assembly 3; wherein the method comprises the steps of

The high-pressure sealing warehouse 100 is in a normal temperature and high pressure state, the pressure is preferably more than 7MPa, the high-pressure sealing warehouse comprises a high-pressure storage warehouse 101 built on the ground or underground, and the high-pressure storage warehouse 101 can be understood as a ground pressure container or an underground cave; the high-pressure reservoir 101 is divided into an air cavity and a liquid cavity by the air bag 102, the air cavity and the liquid cavity have equal pressure and can be adjusted in volume according to the shape of the air bag 102, and air and working media cannot permeate each other; an example of the working substance in this embodiment is liquid carbon dioxide. The pressure of the low-pressure sealing warehouse 200 in the embodiment is preferably below 4MPa in a low-pressure and low-temperature state, the temperature is below the corresponding saturation temperature, and the low-pressure sealing warehouse 200 is provided with a heat preservation layer or heat preservation measures, and can be built on the ground or underground. Because of the higher density of liquid carbon dioxide in low pressure enclosure 200, low pressure enclosure 200 has a smaller volume than high pressure enclosure 100, which are in communication with each other. Thus, in this embodiment, in the stored energy state, the low-pressure liquid carbon dioxide is stored in the low-pressure storage 200, and the air chamber is filled with compressed air; in the energy release state, the low-pressure liquid carbon dioxide is changed into high-pressure liquid carbon dioxide, and the liquid carbon dioxide is stored in the liquid cavity, and the compressed air in the air cavity is discharged.

The specific air cavity and the liquid cavity are separated by the air bag 102, the pressure of the air cavity and the pressure of the liquid cavity are equal, the volume can be adjusted through the scaling of the air bag 102, and the air in the air cavity and the working medium in the liquid cavity cannot mutually permeate; the working fluids in this exemplary embodiment are all liquids. In addition, it should be noted that the material of the air bag 102 has compatibility with the working medium, that is, the air bag 102 will not react with the working medium gas chemically. As shown in fig. 1, the high-pressure reservoir 101 stores air by using a spherical tank pressure vessel, and separates air and working medium in the high-pressure reservoir 101 by using a flexible membrane in the spherical tank, wherein an air cavity is formed in the flexible membrane, and the liquid cavity is located between the flexible membrane and the inner wall of the spherical tank, that is, the air bag 102 is of a deformable and soft membrane structure without tension, the working pressure of the air cavity and the liquid cavity is equal, and the working pressure is preferably greater than 7MPa.

In this embodiment, the pressure of the air chamber and the pressure of the liquid chamber are equal, and the volume adjustment by the scaling of the air chamber 102 can be understood as that compressed air and liquid carbon dioxide can be respectively introduced into the air chamber and the liquid chamber, and the person skilled in the art can adjust the volume of the air chamber and the liquid chamber according to the filling volumes of the compressed air and the liquid carbon dioxide; wherein in the extreme deformed state of the bladder 102, the air or liquid chamber may fill the entire high pressure reservoir 101. The air compression energy release assembly in the embodiment is communicated with the air cavity and is used for introducing or releasing compressed air into the air cavity; the heat storage component 3 can be used for releasing heat or storing heat to the air compression energy release component under different working conditions of the air compression energy release component.

The working medium compression energy release assembly in the embodiment comprises a working medium depressurization and cooling assembly 2 and a working medium pressurization and heating assembly 4; the working medium depressurization and cooling assembly 2 comprises a working medium compression unit and a throttle valve unit; the outlet of the liquid cavity, the throttle valve unit and the inlet of the low-pressure sealing warehouse 200 are sequentially connected through a working medium cooling pipeline; the gas outlet of the low-pressure sealing warehouse 200, the working medium compression unit and the inlet of the throttle valve unit are sequentially connected through a working medium compression pipeline; the liquid outlet of the low-pressure sealing warehouse 200, the working medium boosting and heating assembly 4 and the inlet of the liquid cavity are sequentially connected through a working medium heating pipeline.

The liquid carbon dioxide output by the specific liquid cavity is throttled, depressurized and cooled by a throttle valve unit, so that liquid carbon dioxide with lower temperature and lower pressure is generated, and the liquid carbon dioxide with lower temperature and lower pressure is introduced into an inlet of the low-pressure sealing warehouse 200 and stored in the low-pressure sealing warehouse 200. The liquid carbon dioxide output by the liquid cavity can generate gaseous carbon dioxide when passing through the throttle valve unit, so that the gas outlet of the low-pressure sealing bank 200, the working medium compression unit and the inlet of the throttle valve unit are sequentially connected through the working medium compression pipeline, the gaseous carbon dioxide in the low-pressure sealing bank 200 is compressed by the working medium compression unit to generate working medium compressed gas, and then the working medium compressed gas is input into the inlet of the throttle valve unit for throttling, depressurization and cooling to generate the liquid carbon dioxide for storage. In this embodiment, the liquid outlet of the low-pressure sealing device 200, the working medium boosting and heating assembly 4 and the inlet of the liquid cavity are sequentially connected through a working medium heating pipeline, that is, the liquid carbon dioxide output by the low-pressure sealing device 200 passes through the working medium boosting and heating assembly 4 to heat the liquid carbon dioxide into a working medium in a supercritical state to perform expansion work and power generation, and the gas carbon dioxide after the work and power generation can be condensed and decompressed and then introduced into the liquid cavity.

The embodiment comprises a high-pressure sealing warehouse 100 and a low-pressure sealing warehouse 200, the warehouse capacity is huge, the working medium is stored in a liquid state, the working medium which can be sealed is huge, and when the working medium is carbon dioxide, the high-pressure sealing warehouse 100 and the compressed air energy storage warehouse are shared in use in the system, so that the construction cost is saved. In addition, under the normal operation working condition, the air and working medium are operated under a constant working condition in the compression and expansion processes, so that the energy storage efficiency is high without throttling loss; and the energy storage system in the embodiment has controllable construction cost.

In some embodiments, the air compression energy release assembly comprises an air compression assembly 1, wherein the air compression assembly 1 comprises an air compressor unit and an air heat exchanger unit, an outlet of the air compressor unit being connected to an inlet of the air chamber for air compression; the air heat exchanger unit is used for recovering heat in the compressed air discharged by the air compressor unit and transferring the heat to the heat storage component 3; wherein the compressed air after heat exchange is delivered to the air cavity.

Specifically, the air compressor unit includes a multistage series air compressor; the air heat exchanger unit comprises a plurality of stages of air heat exchangers, wherein the number of the air compressors is the same as that of the air heat exchangers, and the air compressors and the air heat exchangers are in one-to-one correspondence in pairs; air is input into an inlet of the air compressor, the air is compressed to form compressed air, air compression heat is generated in the air compression process, the primary air compressor corresponds to the primary air heat exchanger, heat in the compressed air is recovered by the air heat exchanger in time, and the recovered heat is stored in the heat storage component 3.

As exemplarily shown in fig. 2, the air compressor unit in the present embodiment includes a first air compressor 11 and a second air compressor 12 connected in series; the air heat exchanger unit comprises a first air heat exchanger 13 and a second air heat exchanger 14 connected in series; air is compressed by the first air compressor 11, the output compressed air exchanges heat with a heat transfer medium (such as high-pressure water) from the first cooling tank 32 through the first air heat exchanger 13, the heat transfer medium absorbs heat to raise temperature and is input into the first heat tank 31 for storage, the compressed air is compressed to a specified pressure (such as 1 MPa) through the second air compressor 12, the output compressed air exchanges heat with the heat transfer medium from the second cooling tank 34 through the second air heat exchanger 14, the heat transfer medium absorbs heat to raise temperature and is input into the second heat tank 33 for storage, and the compressed air is input into the air cavity for storage.

In some embodiments, the air compression energy release assembly further comprises an air expansion assembly 5, wherein an inlet of the air expansion assembly 5 is connected with an outlet of the air cavity for expanding the compressed air to generate electricity; the air expansion assembly 5 comprises an air expander unit and an air reheater unit, and compressed air in the air cavity enters the air expander unit to expand and generate electricity; the air reheater unit is used to heat the air entering the air expander unit.

Specifically, an inlet of the air expansion assembly 5 is connected with an outlet of the air cavity and is used for expanding compressed air to generate power, wherein the air expander unit comprises multi-stage air expanders connected in series, the air reheater unit comprises multi-stage air reheaters, the number of the air expanders is the same as that of the air reheaters, and the air expanders and the air reheaters are in one-to-one correspondence in pairs; the inlet of the air expander is connected with an air cavity, the air cavity outputs compressed air, the compressed air exchanges heat with a heat transfer medium with high temperature from the heat storage component 3 through an air reheater, and the compressed air enters the air expander to do work and generate electricity after being heated.

As exemplarily shown in fig. 2 and 3, the air expander unit in the present embodiment includes two stages of air expanders, i.e., a first air expander 51 and a second air expander 52; the air reheater unit includes two stages of air reheaters, namely a first air reheater 53 and a second air reheater 54; the air cavity output compressed air is passed into the first air reheater 53 and exchanges heat with the heat transfer medium from the second heat tank 33; the heat transfer medium releases heat to cool down and then enters the second cooling tank 34 for storage; the compressed air after heat exchange is expanded and generated by the first air expander 51. The air output by the first air expander 51 exchanges heat with the heat transfer medium from the first heat tank 31 through the second air reheater 54, the heat transfer medium releases heat to be cooled, then further releases waste heat, and then the heat is input into the first cold tank 32 for storage, and the compressed air after heat exchange is expanded by the second air expander 52 to generate electricity.

In some embodiments, the working fluid depressurization and cooling assembly 2 further comprises a working fluid heat exchanger unit; wherein the working medium compressor unit is used for compressing liquid carbon dioxide output by the low-pressure sealing warehouse 200; the working medium heat exchanger unit is used for recovering heat of working medium compressed gas discharged by the working medium compressor unit; the working medium compressed gas enters a throttle valve unit and is converted into liquid carbon dioxide and then is delivered into a low-pressure sealing warehouse 200.

The known working medium compression unit generates compression heat when compressing gas carbon dioxide; the compression heat can be recovered by the working medium heat exchanger unit. The specific working medium compression unit compresses gas carbon dioxide to generate working medium compressed gas, the working medium compressed gas exchanges heat with the working medium heat exchanger unit, compression heat in the working medium compressed gas is transferred to the heat storage component 3, and the working medium compressed gas enters the throttle valve unit to be converted into liquid carbon dioxide and then is conveyed into the low-pressure sealing warehouse 200.

Specifically, the working medium compressor unit comprises a plurality of stages of working medium compressors connected in series; the working medium heat exchanger unit comprises a plurality of stages of working medium heat exchangers, wherein the working medium compressors and the working medium heat exchangers have the same quantity, and the working medium compressors and the working medium heat exchangers are matched and correspond to each other one by one. The inlet of the working medium compressor is connected with the gas outlet of the low-pressure sealing bank 200, the working medium compressor is used for inputting gaseous carbon dioxide to form working medium compressed gas, compression heat is generated in the process, the primary working medium compressor is utilized to correspond to the primary working medium heat exchanger, and the compression heat is recovered by utilizing the working medium heat exchanger in time and is stored in the heat storage component 3.

As shown in fig. 2, the working medium compressor unit in the present embodiment includes two-stage working medium compressors, namely, a first working medium compressor 21 and a second working medium compressor 22; the working medium heat exchanger unit comprises two stages of working medium heat exchangers, namely a first working medium intercooler 23 and a second working medium intercooler 24; simultaneously, the gas carbon dioxide in the low-pressure seal bank 200 is compressed by the first working medium compressor 21, the working medium compressed gas output by the first working medium compressor 21 is cooled by the first working medium intercooler 23 and then compressed to the specified pressure by the second working medium compressor 22, and the working medium compressed gas output by the second working medium compressor 22 is cooled by the second working medium intercooler 24 and then is introduced into the throttle valve unit to be converted into liquid carbon dioxide and then is transmitted to the low-pressure seal bank 200 for storage.

In some embodiments, the throttle unit comprises a plurality of stages of throttles in series and an air flow separator 27 between adjacent throttles; the gas outlet of the gas flow separator 27 is connected to a working medium compression line, and the gas outlet thereof is connected to a downstream throttle valve.

Wherein the throttle unit comprises a plurality of throttle valves connected in series, and an air flow separator 27 between adjacent throttle valves. As illustrated in fig. 2-4, the throttle unit includes a first throttle valve 25 and a second throttle valve 26; wherein an air flow separator 27 is arranged between the first throttle valve 25 and the second throttle valve 26; namely, a first throttle valve 25, an airflow separator 27 and a second throttle valve 26 are sequentially arranged on a working medium cooling pipeline; the gas flow separator 27 separates the liquid carbon dioxide and the gas carbon dioxide output from the first throttle valve 25; the separated liquid carbon dioxide enters the second throttle valve 26 and is finally fed to the low pressure seal reservoir 200. The gas outlet of the gas flow separator 27 is connected with a working medium compression pipeline, and the gas carbon dioxide separated by the gas flow separator 27 enters a working medium compressor of an intermediate stage and can be further compressed. In this embodiment, the inlet of the first throttle valve 25 is thus connected to the outlet of the high-pressure reservoir 100 and to the outlet of the working medium heat exchanger corresponding to the last working medium compressor, and the outlet of the second throttle valve 26 is connected to the inlet of the low-pressure reservoir 200.

In some embodiments, the working medium boosting and heating assembly 4 comprises a liquid booster pump 41, a liquid preheater 42, a working medium expander unit and a cooler 49 which are sequentially arranged on a working medium heating pipeline, wherein an inlet of the liquid booster pump 41 is connected with a liquid outlet of the low-pressure sealing warehouse 200; a cooler 49 is connected to the inlet of the liquid chamber; the working medium boosting and heating assembly 4 further comprises a working medium reheater unit which is used for heating the liquid carbon dioxide entering the working medium expander unit.

Specifically, the liquid booster pump 41, the liquid preheater 42, the working medium expander unit and the cooler 49 are sequentially arranged on the working medium heating pipeline, that is, an inlet of the liquid booster pump 41 is connected with a liquid outlet of the low-pressure sealing warehouse 200, and is used for lifting the pressure of the liquid carbon dioxide output by the low-pressure sealing warehouse 200 to be higher than the pressure of the high-pressure sealing warehouse 100, the boosted liquid carbon dioxide is introduced into the liquid preheater 42, the liquid preheater 42 is used for preheating the liquid carbon dioxide and conveying the liquid carbon dioxide to the working medium reheater unit, and the liquid preheater 42 can generate cooling water to supply to peripheral users; the working medium reheater unit can further increase the temperature of the liquid carbon dioxide and convert the liquid carbon dioxide into a supercritical working medium, and the supercritical working medium expands in the working medium expander unit to generate power.

The working medium expander unit comprises a plurality of working medium expanders which are connected in series, the working medium reheater unit comprises a plurality of working medium reheaters, the number of the working medium expanders is the same as that of the working medium reheaters, and the working medium expanders and the working medium reheaters are in one-to-one correspondence in pairs; the inlet of the working medium reheater is connected with the liquid carbon dioxide outlet of the liquid preheater 42, and is used for heating the liquid carbon dioxide, and the working medium enters the working medium reheater to heat and exchange heat with the heat transfer medium with high temperature from the heat storage component 3, so that the working medium temperature is further increased and then converted into the working medium with supercritical state, and then enters the working medium expander to generate electricity and do work.

As shown in fig. 2-3, the working medium expander unit in the present embodiment includes two-stage working medium expanders, namely, a first working medium expander 43 and a second working medium expander 44; the working medium reheater unit comprises a two-stage working medium reheater, namely a first working medium reheater 46 and a second working medium reheater 47; the liquid carbon dioxide output by the liquid preheater 42 enters the first working medium reheater 46 and exchanges heat with the heat transfer medium from the heat storage component 3, the liquid carbon dioxide is heated and then becomes supercritical state to be input into the first working medium expander 43 for expansion power generation, the supercritical state working medium output by the first working medium expander 43 exchanges heat with the heat transfer medium from the heat storage component 3 through the second working medium reheater 47, the supercritical state working medium after heat exchange is expanded and power generation through the second working medium expander 44, and the exhaust gas output by the second working medium expander 44 is cooled through the cooler 49 and then is input into the liquid cavity. In this embodiment, the system is simplified, but the pressure in the low-pressure reservoir is changed greatly, so that the material is easier to fatigue due to the change of the pressure.

In some embodiments, working medium pressure-raising and temperature-raising assembly 4 further comprises a back pressure pipeline; the inlet and outlet of the back pressure pipeline are respectively communicated with the working medium heating pipeline and the inlet of the low-pressure sealing warehouse 200.

Exemplary, wherein during the energy release phase, liquid carbon dioxide in low pressure enclosure 200 is gradually exported, in order to maintain low pressure enclosure 200 at a constant pressure during the energy release phase; and make low pressure reservoir 200 release fully as much as possible in the energy release process, the working medium pressure-increasing and temperature-raising component 4 in this embodiment further includes a back pressure pipeline, wherein the inlet of the back pressure pipeline is connected with the working medium temperature-raising pipeline, and the outlet thereof is connected with the inlet of low pressure reservoir 200. As shown in fig. 4, the working medium expander unit includes a plurality of working medium expanders connected in series, wherein a first working medium expander 43, a second working medium expander 44 and a third working medium expander 45 are provided; the third working medium expander 45 is arranged on the back pressure pipeline; the corresponding working medium reheater unit comprises a first working medium reheater 46, a second working medium reheater 47 and a third working medium reheater 48, wherein the third working medium reheater 48 is also arranged on the back pressure pipeline; the operation methods of the first working medium expander 43, the second working medium expander 44 and the third working medium reheater 48 are the same as those described above, and will not be described again. In this embodiment, a part of the exhaust gas output by the second working medium expander 44 enters the cooler 49 on the working medium heating pipeline to be condensed and then is input into the liquid cavity, and the other part enters the third working medium reheater 48 to exchange heat with the heat transfer medium from the heat storage component 3, and the gas carbon dioxide after heat exchange is expanded by the third working medium expander 45 to generate power and then is input into the low-pressure sealing warehouse 200 through the back pressure pipeline, so that the pressure of the low-pressure sealing warehouse 200 is kept constant in the energy release process. Therefore, in this embodiment, in the initial stage of the energy release stage, the operation condition of the liquid booster pump 41 can be adjusted in real time to maintain the stability of the outlet pressure, and as the liquid level in the low-pressure sealing reservoir 200 decreases, the exhaust part output by the second working medium expander 44 in this embodiment returns to the low-pressure sealing reservoir 200 after being expanded and acting by the third working medium expander 45 to decrease the pressure, so as to maintain the low-pressure sealing reservoir 200 in a reasonable pressure range, and alleviate the operation fatigue of the low-pressure sealing reservoir 200 caused by the decrease of the pressure therein. Therefore, the present embodiment provides a novel pressure maintenance pipeline, in which gas can be filled into the low-pressure sealing device 200 in a staged manner according to the pressure change of the low-pressure sealing device 200 in the energy release process, so as to maintain the low-pressure sealing device 200 within a reasonable pressure range, and meanwhile, the system synchronously recovers the working capacity of the working medium, thereby being beneficial to improving the energy efficiency of the system.

In some embodiments, a plurality of heating channels are provided within the working medium reheater for absorbing waste heat from the heat storage assembly 3 as well as external waste heat.

The working medium reheater is internally provided with a plurality of heating channels, and the outside is provided with waste heat and external waste heat or waste heat, and can be provided for the working medium reheater to heat liquid carbon dioxide. In some embodiments, the heat storage assembly 3 comprises a plurality of groups of high and low temperature tanks respectively connected with the air heat exchanger, the air reheater and the working medium reheater for storing heat from the compressed air; and releasing heat to the air reheater and the working medium reheater; each group of high-low temperature tanks comprises a hot tank and a cold tank which are used in a matched mode; the heat transfer medium in the cold tank is a low-temperature heat transfer medium, and the heat transfer medium can be introduced into the heat exchanger to absorb heat and then the temperature of the heat transfer medium is increased to be stored in the hot tank; the heat transfer medium in the hot tank is a heat transfer medium with high temperature, and the heat transfer medium with high temperature can be introduced into the heat exchanger to release heat, and then the temperature is reduced and stored in the cold tank. In the embodiment, a plurality of groups of high-low temperature tanks can release heat or store heat to the air compression energy release component and the working medium compression energy release component respectively under different working conditions.

In this embodiment, the hot side outlet a of the second air reheater is connected to the inlet corresponding to the third working medium reheater 48; the hot side outlet c of the first air reheater 53, while the outlet of the third working medium reheater 48 corresponding to a is connected to the inlet b of the first cold tank 32; and the outlet of the third working medium reheater 48 corresponding to c is connected with the inlet b of the first cooling tank 32; 2-4, the heat transfer medium from the first heat tank 31 exchanges heat to release heat to cool and then enters the third working medium reheater 48; the gas after heat exchange enters the first cooling tank 32 through an inlet b of the first cooling tank 32; and similarly, the heat transfer medium from the second heat tank 33 exchanges heat to release heat, cools the heat, then enters the third working medium reheater 48, and the heat-exchanged gas enters the second cold tank 34 through the inlet d of the second cold tank 34.

In some embodiments, the integrated carbon dioxide seal and energy storage power generation system in any of the above embodiments is used for generating power, as shown in fig. 5, and the working medium is carbon dioxide, which comprises the following steps:

energy storage stage: the initial stage air chamber and the low pressure enclosure 200 are both in an empty state, and the liquid chamber is filled with liquid carbon dioxide of at least 7 MPa; the energy storage stage comprises a liquid working medium transfer stage and an air compression energy storage stage which are carried out simultaneously;

the liquid working medium transfer phase is as follows: the liquid carbon dioxide is discharged from the liquid cavity and is gradually reduced in pressure and temperature to-50-5 ℃ and the corresponding pressure state of 0.7-4 MPa through the throttle valve, the liquid carbon dioxide after the temperature reduction and the pressure reduction is stored in the low-pressure sealing warehouse 200, the gas carbon dioxide generated in the period is compressed step by step through the working medium compressor, the working medium heat exchanger is used for cooling the working medium compressed gas until the working medium compressed gas is liquefied in the period, and the liquefied working medium compressed gas is returned to the inlet of the throttle valve until the liquid cavity is exhausted;

the air compression energy storage stage is as follows: starting an air compressor to compress air and send the air into an air cavity, and recovering air compression heat by using an air heat exchanger until the compressed air is normal temperature until the air cavity is full of compressed air;

The energy release stage of the liquid working medium is as follows: the liquid carbon dioxide is output from the low-pressure sealing warehouse 200 and boosted to more than 15MPa through the liquid booster pump 41, and then sequentially passes through the liquid preheater 42 and the working medium reheater and is introduced into the working medium expander to generate electricity; the working medium output by the working medium expander is respectively conveyed to the low-pressure sealing warehouse 200 through a back pressure pipeline and is condensed through a cooler 49 on the working medium heating pipeline and then conveyed to the liquid cavity until the liquid carbon dioxide in the low-pressure sealing warehouse 200 is exhausted;

And in the service life of the integrated carbon dioxide sealing and energy storage power generation system, the carbon dioxide liquid is always sealed in the system, and the utilization and sealing of carbon dioxide are realized.

Specifically, the air cavity and the low-pressure sealing warehouse 200 are both in an emptying state in the initial stage, residual gas carbon dioxide is in the low-pressure sealing warehouse 200, and the liquid cavity is filled with liquid carbon dioxide, preferably with the pressure of more than 7MPa, so as to keep the liquid state at normal temperature; the energy storage stage comprises a liquid working medium transfer and storage stage and an air compression energy storage stage which are carried out simultaneously.

Energy storage stage: the liquid carbon dioxide is discharged from a liquid cavity of the high-pressure sealing warehouse 100 and is gradually reduced in pressure and temperature to-50-5 ℃ through a first throttle valve 25 and a second throttle valve 26, the generated liquid carbon dioxide is stored in the low-pressure sealing warehouse 200, the generated gas carbon dioxide is compressed step by step through a working medium compressor, the exhaust gas of the working medium compressor is cooled by a working medium heat exchanger during compression, finally, the compressed gas carbon dioxide is condensed and liquefied and then returns to an inlet of the first throttle valve 25, and the liquid carbon dioxide and the gas carbon dioxide are separated between the first throttle valve 25 and the second throttle valve 26 through a gas-liquid separator; liquid carbon dioxide enters the second throttle valve 26; and returning the gaseous carbon dioxide to the working medium compressor for recompression, and ending the process until the liquid cavity is exhausted. The air compression energy storage process comprises the following steps: starting an air compressor to compress air step by step to a pressure not lower than that of the high-pressure sealing warehouse 100, feeding the air into an air cavity and keeping the pressure of the air cavity constant, and recovering air compression heat to the normal temperature by utilizing an air heat exchanger during the process; the above process ends until the air chamber is filled with compressed air.

Energy release stage: the energy release stage comprises a liquid working medium energy release stage and a compressed air energy release stage which are carried out simultaneously;

The liquid working medium energy release stage comprises the following steps: the liquid carbon dioxide is output from the low-pressure sealing warehouse 200 and is boosted to more than 15MPa through the liquid booster pump 41, then is heated through the liquid preheater 42 and outputs the cold energy in the liquid to a user in a cooling water mode of about 10 ℃, then is heated through the working medium reheater and is introduced into the working medium expander for power generation, the heat of the working medium reheater can adopt low-grade waste heat of more than 80 ℃, the pressure of the carbon dioxide is divided into two paths when reaching the pressure of the high-pressure sealing warehouse 100, the main path is condensed through the cooler 49 and then is input into the liquid cavity of the high-pressure sealing warehouse 100, the secondary path is input into the low-pressure sealing warehouse 200 after passing through the final-stage working medium reheater and the final-stage working medium expander, and the process is finished until the liquid carbon dioxide in the low-pressure sealing warehouse 200 is exhausted.

The compressed air energy release stage comprises the following steps: the air cavity output compressed air of the high-pressure sealing warehouse 100 is heated by the air reheater and then expanded in the air expander to generate power, and the pressure of the air cavity is kept constant in the process of releasing the compressed air until the air cavity is exhausted.

The system can receive the carbon dioxide obtained from the carbon dioxide capturing device, and can be used for energy storage and power generation after filling. For a conventional compressed air energy storage power station with the pressure of 100MW/400MWh, the storage capacity can reach more than 10MPa, the storage capacity can reach 10 square feet (wherein the bedding air capacity is 7 square feet), if the same-capacity air storage is used for the system of the application, the storage capacity only needs 7MPa, and the storage capacity of the air storage can be about 7 ten thousand tons of liquid carbon dioxide, and because the system of the application can be fully charged and discharged when the air storage is used, the storage capacity of the compressed air is 3 times that of the conventional compressed air energy storage power station, and if the air storage is used for storing gas carbon dioxide according to the cascade type energy storage system and the energy storage method disclosed in CN115632488A, the storage capacity can only store thousands of tons. Therefore, the application integrates two purposes of carbon dioxide sealing and energy storage power generation, can seal and store carbon dioxide for more than 30 years, has the functions of low-grade waste heat utilization and cold supply, and has excellent comprehensive benefits.

It should be noted that in the description of the present application, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present application, unless otherwise indicated, the meaning of "a plurality" is two or more.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present application.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any at least one embodiment or example.

While embodiments of the present application have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the application, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the application.

Claims

1. A system for integrating carbon dioxide sequestration and energy storage power generation, comprising

A heat storage assembly; the device is used for releasing heat or storing heat to the air compression energy release assembly and the working medium compression energy release assembly under different working conditions of the air compression energy release assembly and the working medium compression energy release assembly.

2. The system of claim 1, wherein the air compression energy release assembly comprises an air compression assembly, wherein the air compression assembly comprises an air compressor unit and an air heat exchanger unit, an outlet of the air compressor unit being connected to an inlet of the air cavity for air compression; the air heat exchanger unit is used for recovering heat in the compressed air discharged by the air compressor unit and transmitting the heat to the heat storage component, and the compressed air after heat exchange is input into the air cavity.

3. The system of claim 2, wherein the air compressor unit comprises a multistage series of air compressors; the air heat exchanger unit comprises a plurality of stages of air heat exchangers, wherein the air compressors are in one-to-one correspondence with the air heat exchangers.

4. The system of claim 3, wherein the air compression energy release assembly further comprises an air expansion assembly having an inlet coupled to an outlet of the air chamber for expanding compressed air to generate electricity; the air expansion assembly comprises an air expander unit and an air reheater unit, and compressed air in the air cavity enters the air expander unit to be expanded and generate electricity; the air reheater unit is used for heating the compressed air entering the air expander unit.

5. The system of claim 4, wherein the air expander unit comprises a multistage series of air expanders; the air reheater unit comprises a plurality of stages of air reheaters, wherein the air expanders are in one-to-one correspondence with the air reheaters.

6. The system of claim 5, wherein the working fluid depressurization and cooling assembly further comprises a working fluid heat exchanger unit; the working medium compression unit is used for compressing gaseous carbon dioxide output by the low-pressure sealing warehouse; the working medium heat exchanger unit is used for recovering heat of the working medium compressed gas discharged by the working medium compression unit and transmitting the heat to the heat storage component; and the working medium compressed gas enters the throttle valve unit and is converted into liquid carbon dioxide and then is conveyed into the low-pressure sealing warehouse.

7. The system of claim 6, wherein the working fluid compression unit comprises a multi-stage series connected working fluid compressor; the working medium heat exchanger unit comprises a plurality of stages of working medium heat exchangers, wherein the working medium compressors are in one-to-one correspondence with the working medium heat exchangers.

8. The system of claim 7, wherein the throttle valve unit comprises a plurality of stages of throttle valves connected in series and a gas flow separator between adjacent ones of the throttle valves; the gas outlet of the gas flow separator is connected with the working medium compression pipeline, and the gas outlet of the gas flow separator is connected with the downstream throttle valve.

9. The system of claim 7, wherein the working fluid boost temperature elevation assembly comprises a liquid booster pump, a liquid preheater, a working fluid expander unit and a cooler which are sequentially arranged on the working fluid elevation pipeline, wherein an inlet of the liquid booster pump is connected with a liquid outlet of the low-pressure reservoir; the cooler is connected with an inlet of the liquid cavity; the working medium boosting and heating assembly further comprises a working medium reheater unit which is used for heating liquid carbon dioxide entering the working medium expander unit.

10. The system of claim 9, wherein the working substance boost temperature elevation assembly further comprises a back pressure line; and the inlet and the outlet of the back pressure pipeline are respectively communicated with the working medium heating pipeline and the inlet of the low-pressure sealing warehouse.

11. The system of claim 10, wherein the working fluid expander unit comprises a plurality of stages of working fluid expanders in series, wherein the working fluid expander of the last stage is disposed on the back pressure line; the working medium reheater unit comprises a plurality of stages of working medium reheaters, wherein the working medium expansion machines are in one-to-one correspondence with the working medium reheaters.

12. The system of claim 11, wherein a plurality of heating channels are provided within the working medium reheater for absorbing waste heat from the heat storage assembly and external or waste heat.

13. The system of claim 11, wherein the thermal storage assembly comprises a plurality of sets of high and low temperature tanks, each set of high and low temperature tanks comprising a hot tank and a cold tank for paired use; the low-temperature heat transfer medium in the cold tank absorbs heat in the compressed air and becomes high-temperature heat transfer medium to be stored in the hot tank; and the heat transfer medium in the hot tank releases heat to the compressed air and the liquid carbon dioxide in the air reheater and the working medium reheater to become low-temperature heat transfer medium, and the low-temperature heat transfer medium is stored in the cold tank.

14. A method of operating an integrated carbon dioxide seal and energy storage power generation system, wherein power is generated using the system of any one of claims 1-13, comprising the steps of:

The air compression energy storage stage is as follows: starting an air compressor to compress air to the pressure of the liquid cavity, and then sending the air into the air cavity, wherein the air heat exchanger is utilized to recycle air compression heat until the compressed air is normal temperature, and ending when the air cavity is full of compressed air;

The energy release stage of the liquid working medium is as follows: the liquid carbon dioxide is output from the low-pressure sealing warehouse and boosted to more than 15MPa by the liquid booster pump, and is introduced into the working medium expander to generate electricity after sequentially passing through the liquid preheater and the working medium reheater; the working medium pressure output by the working medium expander is reduced to the air cavity pressure; the working medium output by the working medium expander is respectively conveyed to the low-pressure sealing warehouse through a back pressure pipeline and is condensed through a cooler on the working medium heating pipeline and then conveyed to a liquid cavity until liquid carbon dioxide in the low-pressure sealing warehouse is exhausted;