Gas-liquid interconversion compressed carbon dioxide energy storage system and method for utilizing the system's heat of compression.

Abstract

This invention provides a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing the system's compression heat, relating to the field of compressed carbon dioxide energy storage. The gas-liquid interconversion compressed carbon dioxide energy storage system includes a power generation module, which comprises a carbon dioxide pipeline and, sequentially arranged components: a first condenser, a high-pressure liquid storage device, a first evaporator, a turbine unit, a second condenser, a low-pressure liquid storage device, a second evaporator, and a compressor unit. The first condenser condenses the compressed high-pressure gaseous carbon dioxide into a liquid state and stores it in the high-pressure liquid storage device; the first evaporator heats the liquid carbon dioxide back into a gaseous state and sends it to the turbine unit for power generation. The second condenser condenses the carbon dioxide after work is done into a liquid state; the second evaporator heats the liquid carbon dioxide in the low-pressure liquid storage device back into a gaseous state. Using liquid storage significantly reduces storage space and system footprint compared to gaseous storage, lowering construction costs and facilitating flexible deployment.

Description

Technical Field

[0001] This invention belongs to the field of compressed carbon dioxide energy storage technology, and in particular relates to a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing the system's compression heat. Background Technology

[0002] The intermittent and fluctuating nature of renewable energy grid integration affects grid stability, necessitating countermeasures. Carbon dioxide energy storage technology has become a research hotspot due to its environmental friendliness, safety, ability to mitigate fluctuations, high energy density, and low environmental risk.

[0003] However, some problems remain to be solved within the existing technological system. For example, the gas chambers used to store low-pressure gaseous carbon dioxide in the system require a very large space for the overall construction. This not only increases the project's footprint but also raises construction and maintenance costs, thus limiting the further promotion and application of this technology. Summary of the Invention

[0004] In view of this, the present invention provides a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing the system's compression heat, aiming to reduce the construction space required for the gas-liquid interconversion compressed carbon dioxide energy storage system.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a gas-liquid interconversion compressed carbon dioxide energy storage system, including a power generation module. The power generation module includes a carbon dioxide pipeline, and a first condenser, a high-pressure liquid storage device, a first evaporator, a turbine unit, a second condenser, a low-pressure liquid storage device, a second evaporator, and a compressor unit sequentially arranged in the carbon dioxide pipeline. The first condenser receives high-pressure gaseous carbon dioxide compressed by the compressor unit, condenses it into liquid carbon dioxide, and transports it to the high-pressure liquid storage device for storage. The first evaporator receives liquid carbon dioxide output from the high-pressure liquid storage device, heats it into gaseous carbon dioxide, and then feeds it into the turbine unit to generate electricity. The second condenser condenses the carbon dioxide after it has been processed by the turbine unit into liquid carbon dioxide. The second evaporator heats the liquid carbon dioxide output from the low-pressure liquid storage device into gaseous carbon dioxide.

[0007] In one embodiment, the first condenser uses waste cooling from the first ethylene process as its cold source, and the second condenser uses waste cooling from the second ethylene process as its cold source.

[0008] In one embodiment, the heat source for the first evaporator is the waste heat from the first ethylene process, and the heat source for the second evaporator is the waste heat from the second ethylene process.

[0009] In one embodiment, the carbon dioxide pipeline between the turbine unit and the second condenser is provided with a supplementary interface; and / or, the carbon dioxide pipeline between the second evaporator and the compressor unit is provided with a supplementary interface.

[0010] In one embodiment, a carbon dioxide capture device is also included, which is connected to the supplemental interface and an external carbon dioxide emission source.

[0011] In one embodiment, a first transfer pump is provided between the second condenser and the low-pressure liquid storage device; and / or, a second transfer pump is provided between the low-pressure liquid storage device and the second evaporator.

[0012] In one embodiment, the system further includes an energy storage module, a heat absorption device, and a heat release device. The energy storage module includes an energy storage pipeline and a low-temperature storage tank and a high-temperature storage tank disposed in the energy storage pipeline. The heat absorption device is disposed on a carbon dioxide pipeline between the compressor unit and the first condenser to introduce the low-temperature medium in the low-temperature storage tank through the energy storage pipeline and exchange heat with the carbon dioxide compressed by the compressor unit in the carbon dioxide pipeline. The heat release device is disposed on a carbon dioxide pipeline between the first evaporator and the turbine unit to introduce the high-temperature medium in the high-temperature storage tank through the energy storage pipeline and exchange heat with the carbon dioxide to be introduced into the turbine unit in the carbon dioxide pipeline.

[0013] In one embodiment, the medium in the energy storage pipeline is pressurized water or heat transfer oil.

[0014] In one embodiment, the energy storage system further includes a heating branch and a heating storage tank. One end of the heating branch is connected to the energy storage pipeline between the heat absorption device and the high-temperature storage tank, and the other end is connected to the inlet of the heating storage tank. The outlet of the heating storage tank is connected to an external heat user.

[0015] This invention also provides a method for utilizing the system's compression heat. The method is based on the aforementioned gas-liquid interconversion compressed carbon dioxide energy storage system. The method includes an energy storage step and an energy release step. The energy storage step includes: the compressor unit compressing the gaseous carbon dioxide output from the second evaporator into high-pressure gaseous carbon dioxide; the energy storage pipeline being opened, and the low-temperature medium in the low-temperature storage tank flowing into the heat absorption device; the low-temperature medium exchanging heat with the high-pressure gaseous carbon dioxide in the heat absorption device to absorb heat; the heat-absorbed low-temperature medium heating up to form a high-temperature medium and being transported to the high-temperature storage tank for storage; and the high-pressure gaseous carbon dioxide releasing heat after passing through the heat absorption device. Carbon dioxide flows into the first condenser, is condensed into liquid carbon dioxide, and then transported to the high-pressure liquid storage device for storage. The energy release step includes: the liquid carbon dioxide in the high-pressure liquid storage device flows into the first evaporator, is heated into gaseous carbon dioxide by the first evaporator; the energy storage pipeline is opened, the high-temperature medium in the high-temperature storage tank flows into the heat release device, the high-temperature medium and the gaseous carbon dioxide exchange heat in the heat release device to release heat, the high-temperature medium after heat release cools down to form a low-temperature medium and flows back to the low-temperature storage tank; the gaseous carbon dioxide after heat absorption is introduced into the turbine unit to drive the turbine unit to generate electricity.

[0016] This invention provides a gas-liquid interconversion compressed carbon dioxide energy storage system. This system uses liquid carbon dioxide for storage, which significantly reduces the space requirements for storage devices compared to traditional gaseous storage, because the volume of liquid carbon dioxide is much smaller than that of gaseous carbon dioxide for the same mass. This design optimization makes the entire energy storage system more compact, effectively reducing the project's footprint and construction costs, while also enabling flexible deployment of the system in different scenarios. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is an overall schematic diagram of the gas-liquid interconversion compressed carbon dioxide energy storage system provided by the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1. Power generation module; 11. Low-pressure liquid storage device; 12. Compressor unit; 121. First compressor; 122. Second compressor; 13. First condenser; 131. First ethylene process waste cooling; 14. High-pressure liquid storage device; 15. First evaporator; 151. First ethylene process waste heat; 16. Turbine unit; 161. First turbine; 162. Second turbine; 17. Second condenser; 171. Second ethylene process waste cooling; 18. Second evaporator; 181. Second ethylene process waste heat; 2. Energy storage module; 21. Low-temperature storage tank; 22. High-temperature storage tank; 3. Heat absorption device; 31. First heat exchanger; 32. Second heat exchanger; 4. Heat release device; 41. Third heat exchanger; 42. Fourth heat exchanger; 5. Carbon dioxide capture device; 6. Carbon dioxide source; 23. Heating storage tank. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] The intermittent and fluctuating nature of renewable energy grid integration affects grid stability, necessitating countermeasures. Carbon dioxide energy storage technology has become a research hotspot due to its environmental friendliness, safety, ability to mitigate fluctuations, high energy density, and low environmental risk. However, existing technologies still face several unresolved issues. For example, the structural design for carbon dioxide storage in these systems is not scientifically sound, resulting in enormous overall construction space requirements. This not only increases the project's footprint but also raises construction and maintenance costs, thus limiting the further promotion and application of this technology.

[0025] In view of this, the present invention provides a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing the system's compression heat, aiming to reduce the construction space required for the gas-liquid interconversion compressed carbon dioxide energy storage system.

[0026] Please see Figure 1 The gas-liquid interconversion compressed carbon dioxide energy storage system includes a power generation module 1. The power generation module 1 includes a carbon dioxide pipeline, and sequentially arranged within the carbon dioxide pipeline are a first condenser 13, a high-pressure liquid storage device 14, a first evaporator 15, a turbine unit 16, a second condenser 17, a low-pressure liquid storage device 11, a second evaporator 18, and a compressor unit 12. The first condenser 13 receives the high-pressure gaseous carbon dioxide compressed by the compressor unit 12 and condenses it into liquid carbon dioxide, which is then transported to the high-pressure liquid storage device 14 for storage. The first evaporator 15 receives the liquid carbon dioxide output from the high-pressure liquid storage device 14, heats it to convert it into gaseous carbon dioxide, and then feeds it into the turbine unit 16 to drive the turbine unit 16 for power generation. Simultaneously, the second condenser 17 condenses the carbon dioxide after it has been processed by the turbine unit 16 into liquid carbon dioxide for storage in the low-pressure liquid storage device; and the second evaporator 18 heats the liquid carbon dioxide output from the low-pressure liquid storage device 11 into gaseous carbon dioxide for the compressor unit 12 to perform a second compression cycle.

[0027] During system operation, the storage of liquid carbon dioxide, compared to traditional gaseous storage, significantly reduces the space requirements for storage devices because liquid carbon dioxide has a much smaller volume than gaseous carbon dioxide for the same mass. This design optimization makes the entire energy storage system more compact, effectively reducing the project's footprint and construction costs, while also enabling flexible deployment of the system in different scenarios.

[0028] Therefore, the embodiments of the present invention effectively solve the problem of the large storage space required for storage devices in traditional carbon dioxide energy storage systems through the design of liquid storage.

[0029] By adopting a gas-liquid interconversion working mode, the phase change characteristics of carbon dioxide under different pressure and temperature conditions are fully utilized to achieve efficient energy storage and release.

[0030] In some embodiments, the first condenser 13 uses the first ethylene process waste cooling 131 as a cold source, and the second condenser 17 uses the second ethylene process waste cooling 171 as a cold source. "Ethylene process waste cooling" can be understood as the low-temperature and underutilized cold energy resources generated during the ethylene production process, such as the cold energy emitted by the propylene refrigeration system during the ethylene cracking gas separation stage, the cold energy released during the liquefied natural gas (LNG) gasification process, etc.; for example, ethylene process waste cooling can be methane in the ethylene process, the temperature of which is approximately -160°C to 0°C.

[0031] In specific implementation, the first condenser 13 establishes an independent heat exchange loop with the low-temperature methane pipeline of the ethylene process system. High-pressure gaseous carbon dioxide flows in the shell side of the condenser, while low-temperature methane flows in the tube side in the opposite direction, and heat exchange is enhanced through high-efficiency finned tubes. The second condenser 17 is connected to the low-pressure stage loop of the propylene refrigeration system of the ethylene process. It utilizes the evaporative cooling capacity of propylene at 0℃ to -40℃ to condense the low-pressure gaseous carbon dioxide discharged from the turbine unit 16 into liquid. The two condensers are adapted to the waste cooling resources of the ethylene process in different temperature zones, realizing the cascade recovery and utilization of cold energy.

[0032] This invention integrates the waste cooling from the ethylene process to replace traditional external cooling sources, which reduces the energy storage system's dependence on additional energy and enables the cascade utilization of industrial waste energy, significantly improving the system's overall energy efficiency and economy.

[0033] In some embodiments, please refer to Figure 1 The first evaporator 15 uses the first ethylene process waste heat 151 as its heat source, and the second evaporator 18 uses the second ethylene process waste heat 181 as its heat source. "Ethylene process waste heat" refers to the waste heat generated in the ethylene process unit during the cracking reaction, compression, separation and other stages that is higher than the ambient temperature, such as waste heat from the cracking furnace flue gas, waste heat from the quench boiler steam, and waste heat from the interstage cooling of the compressor unit 12; for example, the ethylene process waste heat can be the quench water in the ethylene process, which is at about 50°C.

[0034] In practice, the first evaporator 15 is connected to the quench water system of the ethylene process, using the waste heat of the quench water at around 50°C as a heat source: the high-pressure liquid carbon dioxide output from the high-pressure liquid storage device 14 is depressurized by the throttle valve and enters the tube side of the first evaporator 15, where it undergoes forced convection heat exchange with the circulating quench water in the shell side. After absorbing the waste heat released by the 50°C quench water, it vaporizes into medium-pressure gaseous carbon dioxide, with its pressure controlled at 8-12 MPa to meet the inlet parameters of the turbine unit 16. After heat exchange, the temperature of the quench water drops to around 40°C and returns to the ethylene process quench system to continue participating in the cracked gas cooling cycle. The second evaporator 18 is connected to the waste heat recovery system of the cracking furnace flue gas in the ethylene process unit, using the waste heat of the flue gas at 150-200℃ as a heat source: the liquid carbon dioxide in the low-pressure liquid storage device 11 is pressurized to 2-3MPa by a pump and then enters the second evaporator 18. It exchanges heat with the flue gas in the finned tube heat exchanger, absorbs heat and evaporates into low-pressure gaseous carbon dioxide, and then enters the compressor unit 12 for multi-stage compression. After heat exchange, the temperature of the flue gas drops to below 100℃, which can be further used to preheat boiler feedwater or heat process media, realizing the cascade utilization of waste heat.

[0035] This invention integrates the waste heat from the ethylene process, coupling the first evaporator 15 and the second evaporator 18 with waste heat resources at different temperatures in the ethylene process, forming a gradient utilization chain from low-temperature waste heat to medium-temperature waste heat. This avoids the problem of low evaporation efficiency caused by insufficient temperature of a single heat source, and maximizes the recovery of industrial waste heat.

[0036] In some embodiments, please refer to Figure 1 A supplementary interface is provided for the carbon dioxide pipeline between turbine unit 16 and second condenser 17; and / or, a supplementary interface is provided for the carbon dioxide pipeline between second evaporator 18 and compressor unit 12; this is a further optimization of the stability and adaptability of the gas-liquid interconversion compression carbon dioxide energy storage system, and its core function is to supplement the system with carbon dioxide working fluid in order to cope with working fluid loss or operating condition adjustment needs during long-term operation.

[0037] During system operation, although the sealing of pipelines and equipment has been optimized, long-term high-frequency gas-liquid conversion and pressure fluctuations may lead to trace carbon dioxide leakage. If the total amount of working fluid continues to decrease, it will directly affect the intake air volume of compressor unit 12, the working efficiency of turbine unit 16, and even disrupt the cycle balance. The replenishment interface can replenish the working fluid through an external gas source: In the pipeline between turbine unit 16 and the second condenser 17, carbon dioxide is in a low-pressure gaseous state (or gas-liquid mixture state) after the turbine has done work. Replenishing it here can directly participate in the subsequent condensation process and enter the low-pressure liquid storage device 11, avoiding affecting the normal work of the turbine; In the pipeline between the second evaporator 18 and compressor unit 12, carbon dioxide is in a low-pressure gaseous state and is about to enter compressor unit 12. Replenishing the gaseous working fluid here can directly meet the intake air demand of compressor unit 12, avoid "liquid slugging" damage caused by liquid working fluid, and ensure the stability of the compression process.

[0038] In some embodiments, please refer to Figure 1 The gas-liquid interconversion compressed carbon dioxide energy storage system also includes a carbon dioxide capture device 5, which is connected to the replenishment interface and the external carbon dioxide emission source.

[0039] Adding a carbon dioxide capture device 5 to the gas-liquid interconversion compression carbon dioxide energy storage system, which connects the replenishment interface to the external carbon dioxide emission source, can not only continuously replenish the working fluid of the system by capturing and purifying carbon dioxide from the emission source, reducing the working fluid cost and ensuring cycle stability, but also realize the resource utilization of greenhouse gases to reduce carbon emissions, forming a "capture-storage" synergistic effect and enhancing its comprehensive value in environmental protection and energy utilization.

[0040] In some embodiments, please refer to Figure 1 A first transfer pump is provided between the second condenser 17 and the low-pressure liquid storage device 11; and / or, a second transfer pump is provided between the low-pressure liquid storage device 11 and the second evaporator 18.

[0041] A first transfer pump is installed between the second condenser 17 and the low-pressure liquid storage device 11, and a second transfer pump is installed between the low-pressure liquid storage device 11 and the second evaporator 18 to enhance the stability of liquid carbon dioxide circulation on the low-pressure side. The first transfer pump prevents liquid carbon dioxide from failing to flow to the storage device due to pressure or resistance, ensuring its efficient storage and avoiding a decrease in condensation efficiency. The second transfer pump overcomes resistance or height differences, controls the amount of liquid working fluid entering the evaporator, maintains a stable evaporation process, continuously supplies gas to the compressor unit 12, and prevents fluctuations in compression efficiency. The two pumps improve the controllability of liquid working fluid delivery, optimize the smoothness of low-pressure side circulation, and enhance the system's operational stability and efficiency.

[0042] In some embodiments, please refer to Figure 1To better adapt to fluctuations in electricity demand, the gas-liquid interconversion compression carbon dioxide energy storage system is also equipped with an energy storage module 2, a heat absorption device 3, and a heat release device 4. The energy storage module 2 includes energy storage pipelines, and a low-temperature storage tank 21 and a high-temperature storage tank 22 installed within these pipelines. The heat absorption device 3 is installed on the carbon dioxide pipeline between the compressor unit 12 and the first condenser 13, allowing the low-temperature medium from the low-temperature storage tank 21 to be introduced through the energy storage pipeline and exchanged with the carbon dioxide compressed by the compressor unit 12 in the carbon dioxide pipeline. The heat release device 4 is installed on the carbon dioxide pipeline between the first evaporator 15 and the turbine unit 16, allowing the high-temperature medium from the high-temperature storage tank 22 to be introduced through the energy storage pipeline and exchanged with the carbon dioxide entering the turbine unit 16 in the carbon dioxide pipeline.

[0043] In practice, the energy storage module 2 forms an independent hot and cold circulation loop through the energy storage pipeline. The low-temperature storage tank 21 and the high-temperature storage tank 22 store low-temperature media (such as low-temperature heat transfer oil and antifreeze) and high-temperature media (such as high-temperature heat transfer oil and molten salt) respectively, realizing the temporary storage and cascade utilization of compression heat.

[0044] During the energy storage phase (when grid load is low or renewable energy is abundant), compressor unit 12 compresses low-pressure gaseous carbon dioxide into high-temperature, high-pressure gaseous carbon dioxide. At this time, heat absorption device 3 is activated: the low-temperature medium in the low-temperature storage tank 21 is pumped into the heat absorption device 3 through the energy storage pipeline, where it exchanges heat with the high-temperature, high-pressure gaseous carbon dioxide that has just been compressed in the carbon dioxide pipeline. After absorbing the heat of compression, the low-temperature medium's temperature rises, becoming a high-temperature medium, and is then transported to the high-temperature storage tank 22 for storage. Meanwhile, the high-pressure gaseous carbon dioxide, cooled by heat exchange, enters the first condenser 13, where it is more easily condensed into high-pressure liquid carbon dioxide, reducing the cold source consumption of the first condenser 13.

[0045] During the energy release phase (when the grid load is at its peak or when power demand surges), the gaseous carbon dioxide output from the first evaporator 15 needs to have its parameters further increased to enhance the power generation of the turbine unit 16. At this time, the heat release device 4 is activated: the high-temperature medium in the high-temperature storage tank 22 is pumped into the heat release device 4 through the energy storage pipeline to exchange heat with the gaseous carbon dioxide to be introduced into the turbine unit 16, releasing the stored compression heat to heat the carbon dioxide, further increasing its temperature and pressure, and improving the turbine's working efficiency; the high-temperature medium after heat release is cooled to a low-temperature medium and flows back to the low-temperature storage tank 21 to complete the cycle.

[0046] The embodiments of the present invention, through the setting of energy storage module 2, heat absorption device 3 and heat release device 4, can flexibly adjust the storage and release of compressed heat according to the fluctuation of power demand: more heat is stored when power demand is low and more heat is released when demand is high, which not only avoids the waste of compressed heat, but also dynamically matches the power generation power of turbine unit 16, significantly improving the system's adaptability to power fluctuations.

[0047] In some embodiments, please refer to Figure 1 To improve the compression efficiency of carbon dioxide and reduce system energy consumption, the compressor unit 12 specifically includes a first compressor 121 and a second compressor 122 connected in series. Along the direction of the carbon dioxide pipeline, the second compressor 122 is closer to the high-pressure liquid storage device 14 than the first compressor 121. The heat absorption device 3 includes a first heat exchanger 31 and a second heat exchanger 32. The first heat exchanger 31 is disposed on the carbon dioxide pipeline between the first compressor 121 and the second compressor 122, and the second heat exchanger is disposed on the carbon dioxide pipeline between the second compressor 122 and the high-pressure liquid storage device 14.

[0048] The specific implementation principle is as follows: During the energy storage process, as gaseous carbon dioxide flows sequentially through the first compressor 121 and the second compressor 122 for staged compression, its temperature gradually increases. The first heat exchanger 31 first performs preliminary heat exchange on the carbon dioxide compressed by the first compressor 121, absorbing some of the compression heat and storing it in the high-temperature storage tank 22, thereby reducing the temperature of the carbon dioxide entering the second compressor 122 and preventing increased power consumption of the second compressor 122 due to excessively high temperature. The second heat exchanger 32 then performs deep heat exchange on the high-temperature, high-pressure carbon dioxide at the outlet of the second compressor 122, further recovering the compression heat and lowering the carbon dioxide temperature to closer to the condensation temperature, thereby improving the condensation efficiency of the first condenser 13 and reducing energy loss during the condensation process. Through the synergistic effect of two-stage compression and two-stage heat exchange, not only is the compression efficiency of carbon dioxide improved, but the recovery of compression heat generated at different compression stages is also maximized, providing sufficient thermal energy support for the efficient operation of the turbine unit 16 during the subsequent energy release process, while effectively reducing the overall energy consumption of the system.

[0049] In some embodiments, please refer to Figure 1 In order to achieve the cascade release of carbon dioxide energy and improve the power generation efficiency of turbine unit 16, turbine unit 16 specifically includes a first turbine 161 and a second turbine 162 connected in series. Along the direction of the carbon dioxide pipeline, the second turbine 162 is closer to the high-pressure liquid storage device 14 than the first turbine 161. The heat release device 4 includes a third heat exchanger 41 and a fourth heat exchanger 42. The third heat exchanger 41 is located on the carbon dioxide pipeline between the first evaporator 15 and the first turbine 161, and the fourth heat exchanger 42 is located on the carbon dioxide pipeline between the first turbine 161 and the second turbine 162.

[0050] The specific implementation principle is as follows: During the energy release process, the liquid carbon dioxide output from the high-pressure liquid storage device 14 is heated and vaporized by the first evaporator 15 to form high-pressure gaseous carbon dioxide, which first enters the third heat exchanger 41. The third heat exchanger 41 uses part of the high-temperature medium stored in the high-temperature storage tank 22 to heat the carbon dioxide, enabling it to gain initial kinetic energy and reach the optimal intake parameters of the first turbine 161, driving the first turbine 161 to perform preliminary power generation. The medium-pressure gaseous carbon dioxide discharged from the first turbine 161 then enters the fourth heat exchanger 42, where it exchanges heat again with another part of the high-temperature medium output from the high-temperature storage tank 22, further increasing the temperature and pressure to meet the intake requirements of the second turbine 162, driving the second turbine 162 to perform secondary power generation. Through the combined design of two-stage turbines and two-stage heat exchangers, the cascade release of carbon dioxide energy is achieved, avoiding the loss caused by the one-time energy release in a single-stage turbine. At the same time, the cascade utilization of the high-temperature medium also improves the thermal energy conversion efficiency, significantly improving the overall power generation and energy utilization rate of the turbine unit 16.

[0051] In some embodiments, please refer to Figure 1 The medium in the energy storage pipeline is pressurized water or heat transfer oil.

[0052] In practice, the circulation of pressurized water or heat transfer oil constructs a closed loop for heat storage and release, thereby reducing system energy loss and improving efficiency. Specifically, during the system energy storage phase (when compressor unit 12 is working), the carbon dioxide compressed by compressor unit 12 is in a high-temperature and high-pressure state. At this time, the heat absorption device 3 is activated: pressurized water or heat transfer oil stored in the low-temperature storage tank 21 is introduced into the heat absorption device 3 through the energy storage pipeline to exchange heat with the high-temperature and high-pressure carbon dioxide, absorbing the large amount of heat generated during its compression. Subsequently, it is transported to the high-temperature storage tank 22 through the energy storage pipeline to complete the recovery of compression heat and avoid the heat being directly lost through the first condenser 13, thus preventing waste. During the system energy release phase (when turbine unit 16 generates electricity), the high-pressure liquid storage device 14 outputs... After the liquid carbon dioxide is vaporized in the first evaporator 15, it needs further energy to enhance the turbine's work capacity. At this time, the heat release device 4 is activated: pressurized water or heat transfer oil stored in the high-temperature storage tank 22 is introduced into the heat release device 4 through the energy storage pipeline to exchange heat with the gaseous carbon dioxide to be introduced into the turbine unit 16, releasing the stored heat to the carbon dioxide, further increasing its temperature and enthalpy, thereby achieving more efficient energy conversion in the turbine unit 16; after the pressurized water or heat transfer oil is cooled down, it flows back to the low-temperature storage tank 21 through the energy storage pipeline, completing the medium circulation and preparing for the heat absorption process in the next energy storage stage. The entire process achieves temporary heat storage through the energy storage module 2. With the cooperation of the heat absorption and heat release devices 4, the compression heat that might otherwise be wasted is directed to improve the work efficiency of the energy release stage, forming an internal energy cycle.

[0053] In some embodiments, please refer to Figure 1 In order to expand the application scenarios of the system and realize diversified energy output, the energy storage system also includes a heating branch and a heating storage tank 23. One end of the heating branch is connected to the energy storage pipeline between the heat absorption device 3 and the high temperature storage tank 22, and the other end is connected to the inlet of the heating storage tank 23; the outlet of the heating storage tank 23 is connected to the external heat user.

[0054] During the energy storage process, the heat absorption device 3 absorbs some of the high-temperature medium from the compressed carbon dioxide and introduces it into the heating storage tank 23 through the heating branch for storage. When external heat users such as industrial production and heating systems have heat energy needs, the heating storage tank 23 can output high-temperature liquid to realize the system's heat energy supply in addition to its power generation function, thereby improving the overall energy utilization efficiency.

[0055] This invention also provides a method for utilizing the system's compression heat, based on the gas-liquid interconversion compressed carbon dioxide energy storage system provided in any of the above embodiments. Please refer to... Figure 1 The system utilizes the heat of compression in a manner that includes energy storage and energy release steps.

[0056] The energy storage steps include: the compressor unit 12 compresses the gaseous carbon dioxide in the second evaporator 18 into high-pressure gaseous carbon dioxide; the energy storage pipeline is opened, and the low-temperature medium in the low-temperature storage tank 21 flows into the heat absorption device 3. The low-temperature medium and the high-pressure gaseous carbon dioxide exchange heat in the heat absorption device 3 to absorb heat. After absorbing heat, the low-temperature medium is heated to form a high-temperature medium and is transported to the high-temperature storage tank 22 for storage; the high-pressure gaseous carbon dioxide after releasing heat through the heat absorption device 3 flows into the first condenser 13, is condensed into liquid carbon dioxide by the first condenser 13, and is then transported to the high-pressure liquid storage device 14 for storage. The energy release steps include: liquid carbon dioxide in the high-pressure liquid storage device 14 flows into the first evaporator 15 and is heated into gaseous carbon dioxide by the first evaporator 15; the energy storage pipeline is opened, and the high-temperature medium in the high-temperature storage tank 22 flows into the heat release device 4. The high-temperature medium and the gaseous carbon dioxide exchange heat in the heat release device 4 to release heat. After the heat is released, the high-temperature medium cools down to form a low-temperature medium and flows back to the low-temperature storage tank 21; the gaseous carbon dioxide after absorbing heat is introduced into the turbine unit 16 to drive the turbine unit 16 to generate electricity.

[0057] The specific implementation method is as follows: When there is a power surplus, the compressor unit 12 adjusts the compression intensity according to the grid load, and the heat absorption device 3 recovers the compression heat and converts it into a high-temperature medium for storage. When there is a power shortage, the high-temperature storage tank 22 releases the high-temperature medium as needed, and the heat release device 4 regulates the carbon dioxide parameters to adapt to changes in power generation demand and quickly adjust the power of the turbine unit 16.

[0058] The embodiments of the present invention achieve the synergistic conversion and efficient utilization of thermal energy and electrical energy generated during carbon dioxide compression through the above-described compression heat utilization method.

[0059] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A gas-liquid interconversion compressed carbon dioxide energy storage system, characterized in that, include: The power generation module includes a carbon dioxide pipeline, and a first condenser, a high-pressure liquid storage device, a first evaporator, a turbine unit, a second condenser, a low-pressure liquid storage device, a second evaporator, and a compressor unit arranged sequentially in the carbon dioxide pipeline; the first condenser is used to receive high-pressure gaseous carbon dioxide compressed by the compressor unit, condense it into liquid carbon dioxide, and transport it to the high-pressure liquid storage device for storage; the first evaporator is used to receive liquid carbon dioxide output from the high-pressure liquid storage device, heat it into gaseous carbon dioxide, and then pass it into the turbine unit to generate electricity; The second condenser is used to condense the carbon dioxide after it has been worked on by the turbine unit into liquid carbon dioxide; the second evaporator is used to heat the liquid carbon dioxide output from the low-pressure liquid storage device into gaseous carbon dioxide. A supplemental interface is provided for the carbon dioxide pipeline between the turbine unit and the second condenser; a supplemental interface is provided for the carbon dioxide pipeline between the second evaporator and the compressor unit; The gas-liquid interconversion compressed carbon dioxide energy storage system also includes a carbon dioxide capture device, which is connected to the replenishment interface and an external carbon dioxide emission source. A first transfer pump is provided between the second condenser and the low-pressure liquid storage device; a second transfer pump is provided between the low-pressure liquid storage device and the second evaporator.

2. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 1, characterized in that, The first condenser uses the waste cooling from the first ethylene process as its cold source, and the second condenser uses the waste cooling from the second ethylene process as its cold source.

3. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 1, characterized in that, The first evaporator uses waste heat from the first ethylene process as its heat source, and the second evaporator uses waste heat from the second ethylene process as its heat source.

4. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 1, characterized in that, It also includes energy storage modules, heat absorption devices, and heat release devices; The energy storage module includes an energy storage pipeline, and a cryogenic storage tank and a high-temperature storage tank installed in the energy storage pipeline; The heat absorption device is installed on the carbon dioxide pipeline between the compressor unit and the first condenser to introduce the low-temperature medium in the low-temperature storage tank through the energy storage pipeline and exchange heat with the carbon dioxide compressed by the compressor unit in the carbon dioxide pipeline. The heat release device is installed on the carbon dioxide pipeline between the first evaporator and the turbine unit to introduce the high-temperature medium in the high-temperature storage tank through the energy storage pipeline and exchange heat with the carbon dioxide in the carbon dioxide pipeline that is about to enter the turbine unit.

5. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 4, characterized in that, The medium in the energy storage pipeline is pressurized water or heat transfer oil.

6. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 4, characterized in that, The energy storage system also includes a heating branch and a heating storage tank. One end of the heating branch is connected to the energy storage pipeline between the heat absorption device and the high-temperature storage tank, and the other end is connected to the inlet of the heating storage tank. The outlet of the heating storage tank is connected to an external heat user.

7. A method for utilizing the heat of system compression, characterized in that, Based on the gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 4, the method for utilizing the compression heat of the system includes an energy storage step and an energy release step. The energy storage steps include: the compressor unit compresses the gaseous carbon dioxide output from the second evaporator into high-pressure gaseous carbon dioxide; the energy storage pipeline is opened, and the low-temperature medium in the low-temperature storage tank flows into the heat absorption device, where the low-temperature medium and the high-pressure gaseous carbon dioxide exchange heat to absorb heat; the low-temperature medium after heat absorption heats up to form a high-temperature medium and is transported to the high-temperature storage tank for storage; the high-pressure gaseous carbon dioxide after releasing heat through the heat absorption device flows into the first condenser, is condensed into liquid carbon dioxide by the first condenser, and is then transported to the high-pressure liquid storage device for storage. The energy release step includes: liquid carbon dioxide in the high-pressure liquid storage device flows into the first evaporator and is heated into gaseous carbon dioxide by the first evaporator; the energy storage pipeline is opened, and the high-temperature medium in the high-temperature storage tank flows into the heat release device; the high-temperature medium and the gaseous carbon dioxide exchange heat in the heat release device to release heat; the high-temperature medium after heat release cools down to form a low-temperature medium and flows back to the low-temperature storage tank; the gaseous carbon dioxide after heat absorption is introduced into the turbine unit to drive the turbine unit to generate electricity.

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