Energy charging and discharging method and system for energy storage by compressing carbon dioxide through external heat supplementing water force

Abstract

The invention belongs to the technical field of carbon dioxide compression energy storage, and relates to an energy charging and discharging method and system for external heat supplementing hydraulic compression carbon dioxide energy storage. In the energy charging process, idle energy is used for compressing gaseous carbon dioxide, and the energy utilization rate is increased. Meanwhile, an isothermal compression mode and an adiabatic compression mode are sequentially adopted for compression, so that the compression efficiency is further improved, and the energy consumption is reduced. And in the energy releasing process, liquid carbon dioxide in the gas storage tank is sequentially subjected to isothermal expansion and adiabatic expansion, so that the liquid carbon dioxide is expanded to gaseous carbon dioxide, and the fluid medium is pushed to drive the water feeding pump / water turbine to generate power. In the energy releasing process, a waste heat source is adopted to heat liquid carbon dioxide, and waste heat energy is fully utilized. According to the characteristics of hydraulic compression carbon dioxide energy storage, the isothermal compression-adiabatic compression-isothermal expansion-adiabatic expansion energy charging and discharging thermodynamic process is provided, external low-temperature waste heat is fully utilized, and the circulation efficiency of the system is improved.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide compression energy storage technology, and relates to a charging and releasing method and system for externally replenished hot water hydraulic compression carbon dioxide energy storage. Background Technology

[0002] Compressed air energy storage technology has attracted widespread attention due to its large energy storage capacity, but its energy density is relatively low and it is highly dependent on geographical conditions. Liquefying air for storage can increase energy density, but this process is extremely energy-intensive and suffers significant energy losses.

[0003] Liquid carbon dioxide energy storage technology, which stores CO2 in two liquid phases, has broad development prospects due to its advantages such as high energy density, flexible and compact structure, and low requirements for geographical environment.

[0004] Existing liquid carbon dioxide energy storage systems require a high temperature during the carbon dioxide compression process on the low-pressure side, necessitating the addition of a refrigeration system. Furthermore, both the high-pressure and low-pressure sides require liquid storage tanks, resulting in a complex system structure and increased system investment and operating costs.

[0005] Hydraulic compressed carbon dioxide energy storage systems have a simple structure, require few devices, and have low system investment, but their heat storage and release efficiency is not high. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for charging and releasing energy using externally supplied hot water for hydraulically compressed carbon dioxide energy storage, in order to solve the technical problem of low heat storage and release efficiency in hydraulically compressed carbon dioxide energy storage systems.

[0007] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a method for charging and releasing energy for storing carbon dioxide by externally supplied hot water through hydraulic compression, comprising the following steps: During the charging process, the gaseous carbon dioxide in the storage tank is subjected to isothermal compression and adiabatic compression in sequence, and finally compressed into liquid carbon dioxide. During the energy release process, the liquid carbon dioxide in the gas storage tank undergoes isothermal expansion and adiabatic expansion in sequence, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to drive the feedwater pump / turbine to generate electricity.

[0008] Furthermore, during the charging process, the initial temperature of the gaseous carbon dioxide in the storage tank is 20~25℃, and the initial pressure is 5.0~5.2MPa; After isothermal compression, the temperature of carbon dioxide is 20~25℃, and the pressure of carbon dioxide is 5.4~5.5MPa; After adiabatic compression, the temperature of carbon dioxide is 30~35℃, and the pressure of carbon dioxide is 7.0~7.2MPa.

[0009] Furthermore, during the energy release process, the initial temperature of the liquid carbon dioxide in the storage tank is 30~35℃, and the initial pressure is 7.0~7.2MPa; After isothermal compression, the temperature of carbon dioxide is 30~35℃, and the pressure of carbon dioxide is 5.6~5.8MPa. After adiabatic expansion, the temperature of carbon dioxide is 20~25℃ and the pressure of carbon dioxide is 5.0~5.2MPa.

[0010] Furthermore, the specific steps of sequentially performing isothermal compression and adiabatic compression on the gaseous carbon dioxide in the storage tank are as follows: The fluid medium is pumped into the gas storage tank by a water pump / turbine to perform isothermal compression and adiabatic compression of gaseous carbon dioxide in sequence. The fluid medium inside the gas storage tank is stored in a flexible container.

[0011] Furthermore, the fluid medium is water.

[0012] Furthermore, during the charging process, an external cold source is passed through a heat exchanger, while gaseous carbon dioxide in the storage tank flows through the heat exchanger. The external cold source uses the heat exchanger to absorb heat from the gaseous carbon dioxide, promoting the liquefaction and energy storage of gaseous carbon dioxide. During the energy release process, an external heat source is passed through a heat exchanger, while liquid carbon dioxide in the storage tank flows through the heat exchanger, allowing the liquid carbon dioxide to absorb heat from the external heat source.

[0013] Furthermore, it also includes the following steps: Real-time acquisition of the temperature and pressure of carbon dioxide in the storage tank; Based on the temperature and pressure of carbon dioxide, the flow rate of the external heat source entering the heat exchanger is adjusted by PID control. The power of the feedwater pump / turbine is adjusted by PID control based on the temperature and pressure of carbon dioxide.

[0014] Secondly, the present invention provides an energy storage and charging system for externally supplied hot water and compressed carbon dioxide, comprising: a gas storage tank, wherein the gas storage tank is filled with carbon dioxide, and a flexible container is also provided inside the gas storage tank. The flexible container is connected to a water storage tank via a water pump / turbine. A temperature sensor and a pressure sensor are provided inside the gas storage tank.

[0015] Furthermore, it also includes a heat exchanger, which is connected to the gas storage tank via heat exchange pipelines.

[0016] Furthermore, the water pump / turbine is connected to an electric motor / generator.

[0017] Compared with the prior art, the present invention has the following beneficial effects: In this invention, during the energy charging process, gaseous carbon dioxide in the storage tank undergoes sequential isothermal and adiabatic compression, ultimately compressing it into liquid carbon dioxide. During charging, idle energy is utilized to compress the gaseous carbon dioxide, improving energy utilization. Simultaneously, the sequential use of isothermal and adiabatic compression further enhances compression efficiency and reduces energy consumption. During energy release, the liquid carbon dioxide in the storage tank undergoes sequential isothermal and adiabatic expansion, causing it to expand into gaseous carbon dioxide, driving the fluid medium to power a feedwater pump / turbine for electricity generation. During energy release, waste heat is used to heat the liquid carbon dioxide. This fully utilizes waste heat energy and has low requirements for waste heat temperature. This invention, considering the characteristics of hydraulically compressed carbon dioxide energy storage, proposes a charging and releasing thermodynamic process of isothermal compression-adiabatic compression-isothermal expansion-adiabatic expansion, fully utilizing external low-temperature waste heat and improving the system's cycle efficiency.

[0018] This invention utilizes idle energy to compress gaseous carbon dioxide for energy storage, and heats liquid carbon dioxide using a waste heat source, causing the liquid carbon dioxide to expand into a gaseous state, which in turn drives a feedwater pump / turbine to generate electricity. During the energy charging process, idle energy is used to pump water from a reservoir into a flexible container via the feedwater pump / turbine, thereby compressing the gaseous carbon dioxide in the storage tank to store energy. The compression process includes isothermal compression and adiabatic compression, ultimately compressing it into liquid carbon dioxide. During the energy release process, waste heat is used to heat the liquid carbon dioxide, causing it to vaporize and expand. The expansion process includes isothermal expansion and adiabatic expansion, causing the liquid carbon dioxide to expand into a gaseous state. During the carbon dioxide vaporization and expansion, the water in the flexible container is squeezed out, and the discharged water drives the feedwater pump / turbine, which in turn drives a power generation device to generate electricity, thus achieving energy recovery. In addition, the gas storage tank is equipped with temperature and pressure sensors. The temperature and pressure inside the gas storage tank are acquired in real time by the temperature and pressure sensors. The charging and releasing processes are adjusted in real time according to the temperature and pressure inside the gas storage tank to ensure the stability and accuracy of isothermal compression, adiabatic compression, isothermal expansion and adiabatic expansion, thereby improving the energy circulation efficiency of the system.

[0019] The heat exchanger described in this invention is connected to a gas storage tank via heat exchange pipelines. These pipelines are connected to the gas storage tank but not to the heat exchanger itself. During the energy release process, waste heat is transferred through the heat exchanger to heat the liquid carbon dioxide in the heat exchange pipelines, thereby heating the liquid carbon dioxide in the entire gas storage tank.

[0020] The present invention integrates the electric motor / generator and the water pump / turbine into a single unit, which simplifies the overall structure of the device. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a flowchart of a method according to an embodiment of the present invention; Figure 3 This is a temperature-entropy diagram of the energy charging and discharging process in an embodiment of the present invention; Figure 4 This is a diagram showing the temperature change of the working fluid during the charging and discharging process according to an embodiment of the present invention. Figure 5 This is a diagram showing the pressure and temperature changes during the charging and discharging process according to an embodiment of the present invention.

[0022] The components include: 1. Heat exchanger; 2. Gas storage tank; 3. Electric motor / generator; 4. Water pump / turbine; 5. Water storage tank; 6. Heat exchange pipeline; 7. Flexible container. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings: Example 1: See Figure 1 This invention discloses a method for charging and releasing energy by externally replenished hot water and hydraulically compressed carbon dioxide for energy storage, comprising the following steps: S1, During the charging process, the gaseous carbon dioxide in storage tank 2 is subjected to isothermal compression and adiabatic compression sequentially, ultimately compressed into liquid carbon dioxide. During charging, idle energy is used to compress the gaseous carbon dioxide, improving energy utilization. Simultaneously, the sequential use of isothermal and adiabatic compression further improves compression efficiency and reduces energy consumption. See [link to documentation]. Figure 3 , which is the temperature-entropy diagram of the energy charging and discharging process.

[0026] In this embodiment of the invention, during the charging process, the initial temperature of the gaseous carbon dioxide in the gas storage tank 2 is 20°C, and the initial pressure is 5.0 MPa; see also Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0027] After isothermal compression, the temperature of carbon dioxide is 20℃ and the pressure of carbon dioxide is 5.4MPa. After adiabatic compression, the temperature of carbon dioxide is 30℃ and the pressure of carbon dioxide is 7.0MPa.

[0028] In this embodiment of the invention, the steps of sequentially performing isothermal compression and adiabatic compression on the gaseous carbon dioxide in the gas storage tank 2 are as follows: The fluid medium is pumped into the gas storage tank 2 by the water pump / turbine 4 to perform isothermal compression and adiabatic compression of gaseous carbon dioxide in sequence. The fluid medium in the gas storage tank 2 is stored in the flexible container 7.

[0029] In this embodiment of the invention, during the charging process, an external cold source is passed through heat exchanger 1. At the same time, gaseous carbon dioxide in storage tank 2 flows through heat exchanger 1. The external cold source uses heat exchanger 1 to absorb heat from the gaseous carbon dioxide, promoting the liquefaction and energy storage of gaseous carbon dioxide.

[0030] In this embodiment of the invention, the fluid medium is water.

[0031] S2, during the energy release process, the liquid carbon dioxide in storage tank 2 undergoes isothermal and adiabatic expansion sequentially, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to power the feedwater pump / turbine 4 to generate electricity. During the energy release process, waste heat is used to heat the liquid carbon dioxide. This fully utilizes waste heat energy, and the required waste heat temperature is low, below 50℃. Waste heat at this temperature cannot be recovered and utilized in industrial applications. (See [link to relevant documentation]). Figure 3 , which is the temperature-entropy diagram of the energy charging and discharging process.

[0032] In this embodiment of the invention, during the energy release process, the initial temperature of the liquid carbon dioxide in the gas storage tank 2 is 30°C, and the initial pressure is 7.0 MPa; see also Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0033] After isothermal compression, the temperature of carbon dioxide is 30℃, and the pressure of carbon dioxide is 5.6 MPa. After adiabatic expansion, the temperature of carbon dioxide is 20℃ and the pressure of carbon dioxide is 5.0MPa.

[0034] In this embodiment of the invention, during the energy release process, an external heat source is passed through heat exchanger 1, and at the same time, liquid carbon dioxide in storage tank 2 flows through heat exchanger 1, so that the liquid carbon dioxide absorbs heat from the external heat source through heat exchanger 1.

[0035] In this embodiment of the invention, the following steps are also included: Real-time acquisition of the temperature and pressure of carbon dioxide in storage tank 2; Based on the temperature and pressure of carbon dioxide, the flow rate of the external heat source entering heat exchanger 1 is adjusted by PID control. The power of the feedwater pump / turbine 4 is adjusted by PID control based on the temperature and pressure of carbon dioxide.

[0036] This invention addresses the characteristics of hydrodynamic compression carbon dioxide energy storage by proposing a charge-release thermodynamic process of isothermal compression-adiabatic compression-isothermal expansion-adiabatic expansion, which fully utilizes external low-temperature waste heat and improves the system's cycle efficiency.

[0037] Based on the above method, the present invention also discloses an energy charging and discharging system for externally supplied hot water and hydraulically compressed carbon dioxide energy storage, see [link to relevant documentation]. Figure 2 It includes: a gas storage tank 2, which is filled with carbon dioxide. Idle energy is used to compress the gaseous carbon dioxide to store energy, and waste heat is used to heat the liquid carbon dioxide, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to power the feedwater pump / turbine 4 to generate electricity.

[0038] The gas storage tank 2 also contains a flexible container 7, which is connected to a water storage tank 5 via a water pump / turbine 4. During the charging process, idle energy is used to pump water from the water storage tank 5 into the flexible container 7 via the water pump / turbine 4, thereby compressing the gaseous carbon dioxide in the gas storage tank 2 to store energy. The compression process includes isothermal compression and adiabatic compression, ultimately compressing it into liquid carbon dioxide. During the energy release process, the liquid carbon dioxide is heated by a waste heat source, causing it to vaporize and expand. The expansion process includes isothermal expansion and adiabatic expansion, causing the liquid carbon dioxide to expand into gaseous carbon dioxide. During the vaporization and expansion of carbon dioxide, the water in the flexible container 7 is squeezed out. The discharged water drives the water pump / turbine 4, which in turn drives a power generation device to generate electricity, thus achieving energy recovery. In addition, the gas storage tank 2 is equipped with temperature and pressure sensors. These sensors acquire the temperature and pressure inside the gas storage tank 2 in real time, and adjust the charging and discharging processes accordingly to ensure the stability and accuracy of isothermal compression, adiabatic compression, isothermal expansion, and adiabatic expansion, thereby improving the system's energy cycle efficiency. See also... Figure 4For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0039] In this embodiment of the invention, a heat exchanger 1 is also included. The heat exchanger 1 is connected to the gas storage tank 2 via a heat exchange pipeline 6. The heat exchange pipeline is connected to the gas storage tank 2 but not to the heat exchanger 1. During the energy release process, the waste heat source is passed through the heat exchanger 1, which heats the liquid carbon dioxide in the heat exchange pipeline 6, thereby heating the liquid carbon dioxide in the entire gas storage tank 2. Ultimately, the liquid carbon dioxide vaporizes and expands. The expansion process includes isothermal expansion and adiabatic expansion, causing the liquid carbon dioxide to expand into gaseous carbon dioxide.

[0040] In this embodiment of the invention, the water pump / turbine 4 is connected to an electric motor / generator 3. During the charging process, the electric motor / generator 3 drives the water pump / turbine 4 to pump water from the reservoir 5 into the flexible container 7. During the energy release process, liquid carbon dioxide is heated by a waste heat source, causing it to vaporize and expand. This vaporization and expansion forces water out of the flexible container 7, and the discharged water drives the water pump / turbine 4, which in turn drives the electric motor / generator 3 to generate electricity.

[0041] In this invention, the electric motor / generator 3 and the water pump / turbine 4 are designed as an integrated unit, which helps to simplify the overall structure of the device.

[0042] This invention proposes a dual-loop control system that uses carbon dioxide temperature feedback to control the circulating water flow rate and carbon dioxide pressure feedback to control the power of the feedwater pump / turbine, ensuring that the actual circulation process can proceed according to the design curve.

[0043] This invention stores energy by compressing carbon dioxide and releases energy by expanding carbon dioxide. At the same time, this invention proposes a dual-loop control system that uses carbon dioxide temperature feedback to control the circulating water flow rate and carbon dioxide pressure feedback to control the power of the feedwater pump / turbine. This ensures that the actual circulation process can proceed according to the design curve, thereby improving the energy conversion efficiency of the entire system and enabling more effective energy storage and release.

[0044] Example 2: See Figure 1 This invention discloses a method for charging and releasing energy by externally replenished hot water and hydraulically compressed carbon dioxide for energy storage, comprising the following steps: S1, during the charging process, the gaseous carbon dioxide in storage tank 2 is subjected to isothermal compression and adiabatic compression sequentially, ultimately compressed into liquid carbon dioxide. During charging, idle energy is used to compress the gaseous carbon dioxide, improving energy utilization. Simultaneously, the sequential use of isothermal and adiabatic compression further improves compression efficiency and reduces energy consumption.

[0045] Unlike the above embodiments, in this embodiment, during the charging process, the initial temperature of the gaseous carbon dioxide in the gas storage tank 2 is 22.5℃, and the initial pressure is 5.1MPa; see [link to previous embodiment]. Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0046] After isothermal compression, the temperature of carbon dioxide is 22.5℃ and the pressure of carbon dioxide is 5.45MPa. After adiabatic compression, the temperature of carbon dioxide is 32.5℃ and the pressure of carbon dioxide is 7.1MPa.

[0047] S2, during the energy release process, the liquid carbon dioxide in the gas storage tank 2 undergoes isothermal expansion and adiabatic expansion sequentially, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to power the feedwater pump / turbine 4 to generate electricity. During the energy release process, waste heat is used to heat the liquid carbon dioxide. This fully utilizes waste heat energy and has low requirements for waste heat temperature, which can be below 50℃, a temperature at which waste heat cannot be recovered and utilized in industrial applications.

[0048] In this embodiment of the invention, during the energy release process, the initial temperature of the liquid carbon dioxide in the gas storage tank 2 is 32.5°C, and the initial pressure is 7.1 MPa; see also Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0049] After isothermal compression, the temperature of carbon dioxide is 32.5℃, and the pressure of carbon dioxide is 5.7 MPa. After adiabatic expansion, the temperature of carbon dioxide is 22.5℃ and the pressure of carbon dioxide is 5.1MPa.

[0050] Example 3: See Figure 1 This invention discloses a method for charging and releasing energy by externally replenished hot water and hydraulically compressed carbon dioxide for energy storage, comprising the following steps: S1, during the charging process, the gaseous carbon dioxide in storage tank 2 is subjected to isothermal compression and adiabatic compression sequentially, ultimately compressed into liquid carbon dioxide. During charging, idle energy is used to compress the gaseous carbon dioxide, improving energy utilization. Simultaneously, the sequential use of isothermal and adiabatic compression further improves compression efficiency and reduces energy consumption.

[0051] Unlike the above embodiments, in this embodiment, during the charging process, the initial temperature of the gaseous carbon dioxide in the gas storage tank 2 is 25°C, and the initial pressure is 5.2 MPa; see also Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0052] After isothermal compression, the temperature of carbon dioxide is 25℃ and the pressure of carbon dioxide is 5.5MPa. After adiabatic compression, the temperature of carbon dioxide is 35℃ and the pressure of carbon dioxide is 7.2MPa.

[0053] S2, during the energy release process, the liquid carbon dioxide in the gas storage tank 2 undergoes isothermal expansion and adiabatic expansion sequentially, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to power the feedwater pump / turbine 4 to generate electricity. During the energy release process, waste heat is used to heat the liquid carbon dioxide. This fully utilizes waste heat energy and has low requirements for waste heat temperature, which can be below 50℃, a temperature at which waste heat cannot be recovered and utilized in industrial applications.

[0054] In this embodiment of the invention, during the energy release process, the initial temperature of the liquid carbon dioxide in the gas storage tank 2 is 35°C, and the initial pressure is 7.2 MPa; see also Figure 4 For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0055] After isothermal compression, the temperature of carbon dioxide is 35℃, and the pressure of carbon dioxide is 5.8 MPa. After adiabatic expansion, the temperature of carbon dioxide is 25℃ and the pressure of carbon dioxide is 5.2MPa.

[0056] Example 4: See Figure 2 This embodiment discloses an energy storage and charging system for externally replenished hot water and hydraulically compressed carbon dioxide, including: a heat exchanger 1, a gas storage tank 2, an electric motor / generator 3, a water pump / turbine 4, and a water storage tank 5; During energy storage, the gaseous carbon dioxide in storage tank 2 is first isothermally compressed, then adiabatically compressed into liquid carbon dioxide. During energy release, the liquid carbon dioxide in storage tank 2 first expands isothermally, then expands adiabatically; see [link to relevant documentation]. Figure 4For a diagram showing the temperature change of the working fluid during the charging and discharging process, please refer to [link / reference]. Figure 5 This is a graph showing the pressure and temperature changes during the charging and discharging process.

[0057] During the energy storage process, the initial gaseous carbon dioxide in the gas storage tank 2 has a temperature of 20~25℃ and a pressure of 5.0~5.2MPa. After isothermal compression, the carbon dioxide temperature is 20~25℃ and the pressure is 5.4~5.5MPa. It is then further adiabatically compressed to a liquid state with a temperature of 30~35℃ and a pressure of 7.0~7.2MPa.

[0058] During the energy release process, carbon dioxide first expands isothermally from a temperature of 30~35℃ and a pressure of 7.0~7.2MPa to a temperature of 30~35℃ and a pressure of 5.6~5.8MPa, and then expands adiabatically to a temperature of 20~25℃ and a pressure of 5.0~5.2MPa. During the energy storage process, external cold water exchanges heat with carbon dioxide in storage tank 2 through heat exchanger 1, and carbon dioxide in storage tank 2 changes from gaseous to liquid. During the energy storage process, external hot water exchanges heat with carbon dioxide in storage tank 2 through heat exchanger 1, and the carbon dioxide in storage tank 2 changes from liquid to gas.

[0059] In this embodiment of the invention, the temperature and pressure of carbon dioxide in the gas storage tank 2 are measured. The difference between the temperature signal of carbon dioxide and the target temperature is used to adjust the flow rate of the feed water entering the heat exchanger 1 through PID control. The difference between the pressure of carbon dioxide and the target pressure is used to adjust the power of the feed water pump / turbine 4 through PID control, so as to realize the energy storage and release process curve of claim 2.

[0060] This invention, under the condition of external residual heat, can make full use of residual heat energy by thermodynamically optimizing the charging and discharging process, and has low requirements for residual heat temperature (below 50°C, residual heat at this temperature cannot be recovered and utilized in the industrial field); at the same time, it maximizes the system's cycle efficiency, with a theoretical thermodynamic cycle efficiency of over 110%.

[0061] This invention addresses the characteristics of hydrodynamic compression carbon dioxide energy storage by proposing a charge-release thermodynamic process of isothermal compression-adiabatic compression-isothermal expansion-adiabatic expansion, which fully utilizes external low-temperature waste heat and improves the system's cycle efficiency. This invention proposes a dual-loop control system that uses carbon dioxide temperature feedback to control the circulating water flow rate and carbon dioxide pressure feedback to control the power of the feedwater pump / turbine, ensuring that the actual circulation process can proceed according to the design curve.

[0062] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for charging and releasing energy using externally supplied hot water for hydraulic compression of carbon dioxide for energy storage, characterized in that, Includes the following steps: During the charging process, the gaseous carbon dioxide in the gas storage tank (2) is subjected to isothermal compression and adiabatic compression in sequence, and finally compressed into liquid carbon dioxide. During the energy release process, the liquid carbon dioxide in the gas storage tank (2) undergoes isothermal expansion and adiabatic expansion in sequence, causing the liquid carbon dioxide to expand into gaseous carbon dioxide, which drives the fluid medium to drive the water pump / turbine (4) to generate electricity.

2. The energy charging and releasing method for externally supplied hot water and hydraulically compressed carbon dioxide energy storage according to claim 1, characterized in that, During the charging process, the initial temperature of the gaseous carbon dioxide in the gas storage tank (2) is 20~25℃ and the initial pressure is 5.0~5.2MPa; After isothermal compression, the temperature of carbon dioxide is 20~25℃, and the pressure of carbon dioxide is 5.4~5.5MPa; After adiabatic compression, the temperature of carbon dioxide is 30~35℃, and the pressure of carbon dioxide is 7.0~7.2MPa.

3. The energy storage and charging method for externally supplied hot water and hydraulically compressed carbon dioxide according to claim 1, characterized in that, During the energy release process, the initial temperature of the liquid carbon dioxide in the gas storage tank (2) is 30~35℃ and the initial pressure is 7.0~7.2MPa; After isothermal compression, the temperature of carbon dioxide is 30~35℃, and the pressure of carbon dioxide is 5.6~5.8MPa. After adiabatic expansion, the temperature of carbon dioxide is 20~25℃ and the pressure of carbon dioxide is 5.0~5.2MPa.

4. The energy charging and releasing method for externally supplied hot water and hydraulically compressed carbon dioxide energy storage according to claim 1, characterized in that, The specific steps of performing isothermal compression and adiabatic compression on the gaseous carbon dioxide in the gas storage tank (2) are as follows: The fluid medium is pumped into the gas storage tank (2) by the water pump / turbine (4) to perform isothermal compression and adiabatic compression of gaseous carbon dioxide in sequence; The fluid medium inside the gas storage tank (2) is stored in a flexible container (7).

5. The energy storage and charging method for externally supplied hot water and hydraulically compressed carbon dioxide according to claim 4, characterized in that, The fluid medium is water.

6. The energy storage and charging method for externally supplied hot water and hydraulically compressed carbon dioxide according to claim 1, characterized in that, During the charging process, the external cold source is passed through the heat exchanger (1), and at the same time, the gaseous carbon dioxide in the gas storage tank (2) flows through the heat exchanger (1). The external cold source uses the heat exchanger (1) to absorb the heat in the gaseous carbon dioxide and promote the liquefaction and energy storage of gaseous carbon dioxide. During the energy release process, an external heat source is passed through a heat exchanger (1), and at the same time, liquid carbon dioxide in the gas storage tank (2) flows through the heat exchanger (1), so that the liquid carbon dioxide absorbs heat from the external heat source through the heat exchanger (1).

7. The energy storage and charging method for externally supplied hot water and hydraulically compressed carbon dioxide according to claim 6, characterized in that, It also includes the following steps: The temperature and pressure of carbon dioxide in the gas storage tank (2) are obtained in real time; Based on the temperature and pressure of carbon dioxide, the flow rate of the external heat source entering the heat exchanger (1) is adjusted by PID control; Based on the temperature and pressure of carbon dioxide, the power of the feedwater pump / turbine (4) is adjusted by PID control.

8. An energy storage and charging system for externally supplied hot water and hydraulically compressed carbon dioxide, used to implement the method described in any one of claims 1 to 6, characterized in that, include: The gas storage tank (2) is filled with carbon dioxide. The gas storage tank (2) is also equipped with a flexible container (7). The flexible container (7) is connected to a water storage tank (5) through a water pump / turbine (4). The gas storage tank (2) is equipped with a temperature sensor and a pressure sensor.

9. The energy storage and discharging system for externally supplied hot water and hydraulically compressed carbon dioxide according to claim 8, characterized in that, It also includes a heat exchanger (1), which is connected to a gas storage tank (2) via a heat exchange pipeline (6), and the heat pipeline is connected to the gas storage tank (2).

10. The energy storage and discharging system for externally replenished hot water and hydraulically compressed carbon dioxide according to claim 8, characterized in that, The water pump / turbine (4) is connected to an electric motor / generator (3).

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