Gas-liquid interconversion compressed carbon dioxide energy storage system and method for utilizing system compression heat

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, whose carbon dioxide pipeline sequentially includes a low-pressure gas storage device, a compressor unit, a first condenser, a high-pressure liquid storage device, a first evaporator, and a turbine unit. The first condenser condenses the compressed carbon dioxide into a liquid state and stores it in the high-pressure liquid storage device. The first evaporator heats the liquid carbon dioxide into a gaseous state and then feeds it into the turbine unit for power generation. The system has a replenishment interface to receive external carbon dioxide and a release interface to release carbon dioxide. This structure realizes carbon dioxide state conversion and energy storage and release, laying the foundation for optimization combined with industrial waste energy, while ensuring stable and safe system operation through interface settings.

Description

Technical Field

[0001] This invention belongs to the field of compressed carbon dioxide energy storage technology, and particularly 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] With the large-scale development and utilization of renewable energy, energy storage technology has become a key support for solving its intermittent and fluctuating problems. Compressed carbon dioxide energy storage technology has gradually become a research hotspot in the field of energy storage due to its advantages such as high energy density and environmental friendliness. Among them, the gas-liquid interconversion structure has attracted widespread attention due to its high medium state conversion efficiency.

[0003] The cycle efficiency of existing gas-liquid interconversion compression carbon dioxide energy storage systems is limited by the finite amount of recovered heat sources. Meanwhile, a large amount of carbon dioxide emissions generated in industrial production (such as refining processes) are not effectively recovered and utilized, and low-grade energy sources such as waste heat from ethylene production are often directly emitted, resulting in resource waste. 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 solve the problems of limited heat sources, waste of industrial carbon dioxide emissions, and low utilization rate of low-grade energy in the prior art.

[0005] The technical solution of this invention is implemented as follows: 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 low-pressure gas storage device, a compressor unit, a first condenser, a high-pressure liquid storage device, a first evaporator, and a turbine 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 introduces it into the turbine unit to generate electricity. The carbon dioxide pipeline and / or the low-pressure gas storage device are provided with a replenishment interface for receiving external carbon dioxide; the low-pressure gas storage device and / or the high-pressure liquid storage device are provided with a release interface for releasing carbon dioxide to the outside.

[0006] In one embodiment, the carbon dioxide pipeline between the low-pressure gas storage device and the compressor unit is provided with the supplementary interface; and / or, the carbon dioxide pipeline between the low-pressure gas storage device and the turbine unit 16 is provided with the supplementary interface.

[0007] In one embodiment, a carbon dioxide capture device is also included, the inlet of which is connected to a carbon dioxide emission source in the refining process, and the outlet of which is connected to the supplementary interface.

[0008] In one embodiment, the capture device includes a purification component for removing impurities from externally input carbon dioxide.

[0009] In one embodiment, the low-pressure gas storage device and the high-pressure liquid storage device are respectively equipped with pressure sensors. The carbon dioxide capture device is electrically connected to the low-pressure gas storage device and the high-pressure liquid storage device with a controller. The controller adjusts the operating power of the carbon dioxide capture device according to the pressure signal from the pressure sensor.

[0010] In one embodiment, the first condenser uses room temperature condensate as a cold source.

[0011] In one embodiment, the first evaporator uses waste heat from the ethylene process as a heat source.

[0012] In one embodiment, the carbon dioxide pipeline between the compressor unit and the first condenser, and the carbon dioxide pipeline between the high-pressure liquid storage device and the first evaporator, are connected via a heat exchanger for heat exchange.

[0013] This invention also provides a method for utilizing the heat of system compression. This method is based on a gas-liquid interchange compressed carbon dioxide energy storage system. The gas-liquid interchange compressed carbon dioxide energy storage system includes a power generation module, a carbon dioxide pipeline, and a low-pressure gas storage device, a compressor unit, a first condenser, a high-pressure liquid storage device, a first evaporator, and a turbine unit sequentially arranged 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 carbon dioxide pipeline and / or... Alternatively, the low-pressure gas storage device may be equipped with a supplementary interface connected to the outside, which is used to receive external carbon dioxide; the low-pressure gas storage device and / or the high-pressure liquid storage device may be equipped with a release interface connected to the outside, which is used to release carbon dioxide to the outside; the method for utilizing the system's compression heat includes: the compressor unit compressing low-pressure gaseous carbon dioxide to form high-pressure gaseous carbon dioxide; the high-pressure gaseous carbon dioxide entering the first condenser to condense into high-pressure liquid carbon dioxide and then entering the high-pressure liquid storage device for storage; the first evaporator heating the high-pressure liquid carbon dioxide in the high-pressure liquid storage device to evaporate the liquid carbon dioxide into gaseous carbon dioxide, and the gaseous carbon dioxide driving the turbine unit to generate electricity.

[0014] In one embodiment, a heat exchanger is connected to the carbon dioxide pipeline between the compressor unit and the first condenser, and to the carbon dioxide pipeline between the high-pressure liquid storage device and the first evaporator. The steps for the high-pressure gaseous carbon dioxide before entering the first condenser include: releasing compression heat through the heat exchanger, and transferring the compression heat to the high-pressure liquid carbon dioxide in the first evaporator to supplement the heating energy of the high-pressure liquid carbon dioxide in the first evaporator; at the same time, the temperature of the high-pressure gaseous carbon dioxide decreases after the heat is released by the heat exchanger, and then it enters the first condenser for condensation.

[0015] This invention constructs a complete gas-liquid interconversion energy storage-power generation link by sequentially arranging a low-pressure gas storage device, a compressor unit, a first condenser, a high-pressure liquid storage device, a first evaporator, and a turbine unit on a carbon dioxide pipeline. This achieves the state transformation of carbon dioxide from "low-pressure gaseous state to high-pressure gaseous state to high-pressure liquid state to gaseous state," and the storage and release of energy. This lays the structural foundation for subsequent optimization methods such as combining industrial waste energy and recovering compression heat. Simultaneously, by setting supplementary interfaces in the carbon dioxide pipeline and / or the low-pressure gas storage device, external carbon dioxide can be received in a timely manner to compensate for media losses during system operation, ensuring the continuous and stable operation of the energy storage-power generation cycle. It also provides interface conditions for integrating external gas sources such as industrial carbon dioxide emission sources. Furthermore, by setting release interfaces in the low-pressure gas storage device and / or the high-pressure liquid storage device, carbon dioxide can be released in a timely manner under abnormal system pressure conditions, preventing equipment damage due to overpressure and ensuring system operational safety. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is an overall schematic diagram of the gas-liquid interconversion compressed carbon dioxide energy storage system provided by the present invention.

[0018] Explanation of reference numerals in the attached figures: 1. Power generation module; 11. Low-pressure gas storage device; 12. Compressor unit; 121. First compressor; 122. Second compressor; 13. First condenser; 131. Condensate; 14. High-pressure liquid storage device; 15. First evaporator; 151. Waste heat from ethylene process; 16. Turbine unit; 161. First turbine; 162. Second turbine; 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. Detailed Implementation

[0019] 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.

[0020] 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.

[0021] 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.

[0022] With the large-scale development and utilization of renewable energy, energy storage technology has become a key support for solving its intermittent and fluctuating problems. Compressed carbon dioxide energy storage technology has gradually become a research hotspot in the field of energy storage due to its advantages such as high energy density and environmental friendliness. Among them, the gas-liquid interconversion structure has attracted widespread attention due to its high medium state conversion efficiency.

[0023] Existing gas-liquid interconversion compression carbon dioxide energy storage systems often face the problem of carbon dioxide medium loss in actual operation. At the same time, a large amount of carbon dioxide emissions generated in industrial production (such as refining processes) are not effectively recovered and utilized, and low-grade energy sources such as propylene waste heat generated in industrial processes are often directly emitted, resulting in resource waste.

[0024] In view of this, embodiments of the present invention provide a gas-liquid interconversion compressed carbon dioxide energy storage system, which aims to solve the problems of carbon dioxide medium loss, industrial carbon dioxide emission waste, and low utilization rate of low-grade energy in the prior art.

[0025] Please see Figure 1The gas-liquid interconversion compressed carbon dioxide energy storage system includes a power generation module 1, which includes a carbon dioxide pipeline and, sequentially arranged in the carbon dioxide pipeline, a low-pressure gas storage device 11, a compressor unit 12, a first condenser 13, a high-pressure liquid storage device 14, a first evaporator 15, and a turbine unit 16. The low-pressure gas storage device 11 is used to store gaseous carbon dioxide, while the high-pressure gas storage device is used to store liquid carbon dioxide. The first condenser 13 is used to receive the high-pressure gaseous carbon dioxide compressed by the compressor unit 12, condense it into liquid carbon dioxide, and transport it to the high-pressure liquid storage device 14 for storage; the first evaporator 15 is used to receive the liquid carbon dioxide output from the high-pressure liquid storage device 14, heat it into gaseous carbon dioxide, and then pass it into the turbine unit 16 to generate electricity.

[0026] The working principle is as follows: In the energy storage stage, low-pressure gaseous carbon dioxide in the low-pressure gas storage device 11 enters the compressor unit 12, and after compression, it forms high-pressure gaseous carbon dioxide, which then enters the first condenser 13. The first condenser 13 condenses the high-pressure gaseous carbon dioxide into liquid carbon dioxide and transports it to the high-pressure liquid storage device 14 for storage, achieving efficient energy storage. In the energy release stage, the liquid carbon dioxide in the high-pressure liquid storage device 14 is transported to the first evaporator 15, where it is heated and evaporated into gaseous carbon dioxide. The gaseous carbon dioxide enters the turbine unit 16, expands, and performs work, driving the turbine unit 16 to generate electricity, completing the energy release process.

[0027] Furthermore, the carbon dioxide pipeline and / or the low-pressure gas storage device 11 are provided with a supplementary interface for connecting to the outside world, which is used to receive carbon dioxide from the outside world; the low-pressure gas storage device 11 and / or the high-pressure liquid storage device 14 are provided with a release interface for connecting to the outside world, which is used to release carbon dioxide to the outside world.

[0028] By setting up a supplementary interface, carbon dioxide generated in industrial production (such as emissions from refining processes) can be introduced into the system, effectively replenishing any carbon dioxide medium loss that may occur during operation, while simultaneously enabling the recovery and reuse of industrial carbon dioxide and reducing carbon emissions. The release interface allows for the safe release of carbon dioxide in case of abnormal system pressure or when maintenance is required, ensuring stable system operation.

[0029] In summary, the gas-liquid interconversion compressed carbon dioxide energy storage system provided in this embodiment of the invention includes a power generation module 1. The power generation module 1 includes a carbon dioxide pipeline, and a low-pressure gas storage device 11, a compressor unit 12, a first condenser 13, a high-pressure liquid storage device 14, a first evaporator 15, and a turbine unit 16 arranged sequentially in the carbon dioxide pipeline. The first condenser 13 is used to receive high-pressure gaseous carbon dioxide compressed by the compressor unit 12, condense it into liquid carbon dioxide, and transport it to the high-pressure liquid storage device 14 for storage. The first evaporator 15 is used to receive liquid carbon dioxide output from the high-pressure liquid storage device 14, heat it into gaseous carbon dioxide, and then pass it into the turbine unit 16 to generate electricity. The carbon dioxide pipeline and / or the low-pressure gas storage device 11 are provided with a supplementary interface for connecting to the outside world, which is used to receive external carbon dioxide. The low-pressure gas storage device 11 and / or the high-pressure liquid storage device 14 are provided with a release interface for connecting to the outside world, which is used to release carbon dioxide to the outside world. This invention, through the sequential arrangement of a low-pressure gas storage device 11, a compressor unit 12, a first condenser 13, a high-pressure liquid storage device 14, a first evaporator 15, and a turbine unit 16 on a carbon dioxide pipeline, constructs a complete gas-liquid interconversion energy storage-power generation link. This achieves the state conversion of carbon dioxide from "low-pressure gaseous state to high-pressure gaseous state to high-pressure liquid state to gaseous state," and the storage and release of energy. This lays a structural foundation for subsequent optimization methods such as combining industrial waste energy and recovering compression heat. Simultaneously, by setting supplementary interfaces in the carbon dioxide pipeline and / or the low-pressure gas storage device 11, external carbon dioxide can be received in a timely manner to compensate for media losses during system operation, ensuring the continuous and stable operation of the energy storage-power generation cycle. It also provides interface conditions for integrating external gas sources such as industrial carbon dioxide emission sources. Furthermore, by setting release interfaces in the low-pressure gas storage device 11 and / or the high-pressure liquid storage device 14, carbon dioxide can be released in a timely manner under abnormal system pressure conditions, preventing equipment damage due to overpressure and ensuring system operational safety.

[0030] In some embodiments, please refer to Figure 1 To 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 the energy storage pipelines. The medium within the energy storage pipelines can be water and / or water vapor. 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 pipelines and exchanged with the carbon dioxide compressed by the compressor unit 12 in the carbon dioxide pipelines. 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 pipelines and exchanged with the carbon dioxide entering the turbine unit 16 in the carbon dioxide pipelines.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In some embodiments, please refer to Figure 1 Considering that carbon dioxide source 6 is carbon dioxide produced in industrial production, which is in a normal temperature gaseous state (usually 25°C), the specific location of the supplementary interface in the system is selected accordingly. Specifically, a supplementary interface is provided in the carbon dioxide pipeline between the low-pressure gas storage device 11 and the compressor unit 12; and / or, a supplementary interface is provided in the carbon dioxide pipeline between the low-pressure gas storage device 11 and the turbine unit 16.

[0036] If the supplementary interface is located between the low-pressure gas storage device 11 and the compressor unit 12, ambient temperature gaseous carbon dioxide is directly supplied to the low-pressure pipeline before the inlet of the compressor unit 12, mixing with the low-pressure gaseous carbon dioxide output from the low-pressure gas storage device 11. Since both are at low pressure and their temperatures are close (the gas inside the low-pressure gas storage device 11 is usually at ambient temperature or slightly below ambient temperature), the temperature of the mixed medium is stable, avoiding localized pipeline stress or fluctuations in the inlet parameters of the compressor unit 12 caused by excessive temperature differences. If the supplementary interface is located between the low-pressure gas storage device 11 and the turbine unit 16, the exhaust gas from the turbine unit 16 is usually low-pressure gaseous carbon dioxide, and because it retains a small amount of residual heat after work (its temperature is slightly higher than ambient temperature), ambient temperature gaseous carbon dioxide is supplied to this section of the pipeline and can mix with the turbine exhaust gas. The residual heat of the turbine exhaust gas is used to heat the ambient temperature gas to near the turbine exhaust temperature (usually 30-50℃) before it enters the low-pressure gas storage device 11 for storage. If the low-pressure gas storage device 11 is equipped with a replenishment interface, room temperature gaseous carbon dioxide can be directly replenished into the low-pressure gas storage device 11 and mixed evenly with the low-pressure gaseous carbon dioxide already stored in the device through gas stirring or natural convection inside the device.

[0037] The location of the supplementary interface can be selected according to the application scenario. For example, for room temperature gaseous carbon dioxide with pressure close to that of the low-pressure gas storage device 11, it can be directly connected to the low-pressure gas storage device 11; for emission sources with pressure slightly higher than that of the low-pressure pipeline, it can be connected to the pipeline between the low-pressure gas storage device 11 and the compressor unit 12 to reduce additional pressurization energy consumption; and for scenarios that require preheating using turbine exhaust waste heat, it can be connected to the pipeline between the low-pressure gas storage device 11 and the turbine unit 16 to improve energy utilization efficiency.

[0038] The embodiments of the present invention can flexibly adapt to the pressure and temperature characteristics of different industrial carbon dioxide emission sources by selecting multiple locations for the supplementary interface.

[0039] In some embodiments, please refer to Figure 1 Considering that the carbon dioxide emitted from refining and chemical processes typically contains a certain concentration of impurities, and that pressure and temperature fluctuate, the system is also equipped with a carbon dioxide capture device 5. The inlet of the carbon dioxide capture device 5 is connected to the carbon dioxide emission source of the refining and chemical process, and the outlet of the carbon dioxide capture device 5 is connected to the replenishment interface.

[0040] Furthermore, the capture device includes a purification component. This purification component is used to remove impurities from the carbon dioxide introduced from the outside.

[0041] In practical implementation, the purification components at the supplementary interface employ a multi-stage purification structure to precisely remove impurities such as sulfides, moisture, hydrocarbons, and solid particles that may be present in externally input carbon dioxide (such as industrial emissions, purchased gas sources, etc.): a front-end filter module intercepts solid particles to prevent pipeline blockage; the middle section uses adsorption modules (such as activated carbon and molecular sieves) to adsorb sulfides and hydrocarbons, preventing them from corroding metal components such as compressor unit 12 and condenser; and the rear end is equipped with a drying unit (such as silica gel desiccant or membrane separation device) to remove moisture, preventing freezing and pipeline blockage or affecting the carbon dioxide phase change efficiency under low-temperature conditions.

[0042] In some embodiments, please refer to Figure 1 The low-pressure gas storage device 11 and the high-pressure liquid storage device 14 are respectively equipped with pressure sensors. The carbon dioxide capture device 5 is electrically connected to the low-pressure gas storage device 11 and the high-pressure liquid storage device 14 by a controller. The controller adjusts the operating power of the carbon dioxide capture device 5 according to the pressure signal from the pressure sensor.

[0043] In practical implementation, pressure sensors on the low-pressure gas storage device 11 and the high-pressure liquid storage device 14 can collect the internal pressure parameters of both devices in real time and transmit them to the controller. The controller has a built-in pressure threshold range set according to the system's rated operating parameters and performs dynamic comparison and analysis of the real-time pressure data. When the pressure of either device is detected to be lower than the lower threshold limit, the controller determines that the system medium is insufficient and immediately increases the operating power of the carbon dioxide capture device 5 to increase the gas supply. When the pressure is higher than the upper threshold limit, the controller reduces the power of the capture device or suspends its operation. If necessary, it will release pressure at the release interface. During the natural pressure fluctuations of the system's energy storage / release cycle, the capture power can also be adjusted in advance through predictive control to avoid large pressure fluctuations.

[0044] In some embodiments, please refer to Figure 1 The first condenser 13 uses ambient temperature condensate 131 (temperature 20 to 25°C) as a cold source; and / or, the first evaporator 15 uses ethylene process waste heat 151 as a heat source. "Ethylene process waste heat 151" refers to the waste heat generated in the ethylene 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, ethylene process waste heat 151 can be quench water in the ethylene process, which is at about 50°C.

[0045] In practice, after high-pressure gaseous carbon dioxide enters the first condenser 13, it exchanges heat with the room-temperature condensate flowing through the heat exchange channel of the first condenser 13. After releasing heat, the carbon dioxide condenses into high-pressure liquid carbon dioxide, while the condensate absorbs heat and its temperature rises slightly (still meeting the requirements of its subsequent processes). No additional energy is needed to drive the refrigeration equipment, which greatly reduces the energy consumption of the condensation process.

[0046] The first evaporator 15 is connected to the quench water system of the ethylene process, using the waste heat of the quench water at about 50°C as a heat source: the high-pressure liquid carbon dioxide output from the high-pressure liquid storage device 14 enters the first evaporator 15 and exchanges heat with the circulating quench water, absorbing the waste heat of the quench water and evaporating into gaseous carbon dioxide to meet the power requirements of the turbine unit 16; the cooled quench water after heat exchange is returned to the ethylene process for recycling, realizing the resource recovery of industrial waste heat.

[0047] This invention integrates the waste heat from the ethylene process to replace traditional external heat 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.

[0048] In some embodiments, please refer to Figure 1 The carbon dioxide pipeline between the compressor unit 12 and the first condenser 13, and the carbon dioxide pipeline between the high-pressure liquid storage device 14 and the first evaporator 15, are connected through a heat exchanger for heat exchange.

[0049] In practice, the pipeline between compressor unit 12 and first condenser 13 carries freshly compressed, high-temperature, high-pressure gaseous carbon dioxide (carrying a large amount of heat of compression, which needs to be released to facilitate subsequent condensation); the pipeline between high-pressure liquid storage device 14 and first evaporator 15 carries high-pressure liquid carbon dioxide to be evaporated (which needs to absorb heat to be converted into gaseous state to drive the turbine). When the two exchange heat through the heat exchanger, the heat of compression released by the high-temperature gaseous carbon dioxide can be directly absorbed by the low-temperature liquid carbon dioxide, achieving a match between the heat release end and the heat absorption end, which conforms to the logic of energy cascade utilization.

[0050] The embodiments of the present invention can recover redundant heat generated during the compression process (otherwise it would need to be released additionally through the condenser), reducing the dependence of the first evaporator 15 on external heat sources (such as waste heat from ethylene); at the same time, high-temperature gaseous carbon dioxide enters the first condenser 13 after pre-cooling.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 a portion 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 portion 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.

[0055] This invention also provides a method for utilizing the heat of system compression, based on the gas-liquid interconversion compression carbon dioxide energy storage system provided in any of the above embodiments. Please refer to... Figure 1 The utilization method includes: the compressor unit 12 compresses low-pressure gaseous carbon dioxide to form high-pressure gaseous carbon dioxide; the high-pressure gaseous carbon dioxide enters the first condenser 13, condenses into high-pressure liquid carbon dioxide, and then enters the high-pressure liquid storage device 14 for storage; the first evaporator 15 heats the high-pressure liquid carbon dioxide in the high-pressure liquid storage device 14, causing the liquid carbon dioxide to evaporate into gaseous carbon dioxide, and the gaseous carbon dioxide drives the turbine unit 16 to generate electricity.

[0056] The energy conversion principle is as follows: In the energy storage stage, the compressor unit 12 consumes external electrical energy (such as off-peak electricity from the power grid or surplus renewable energy) to compress low-pressure gaseous carbon dioxide. During this process, electrical energy is converted into pressure energy (pressure increase) and heat energy (compression work generates heat of compression) of carbon dioxide, turning it into a high-temperature, high-pressure gaseous state, completing the conversion of "electrical energy → pressure energy + heat energy". In the energy release stage, the high-pressure liquid carbon dioxide absorbs heat (including recovered heat of compression and external industrial waste heat) in the first evaporator 15, evaporating into a high-pressure gaseous state. The stored pressure energy and heat energy are converted into mechanical energy that drives the turbine unit 16 to rotate, and then the mechanical energy is converted into electrical energy through the generator, realizing the reverse conversion of "pressure energy + heat energy → mechanical energy → electrical energy".

[0057] The principle of carbon dioxide phase change regulation is as follows: During energy storage, high-temperature, high-pressure gaseous carbon dioxide is cooled by a condenser, releasing heat and condensing into a high-pressure liquid state. This liquid state is then stored in the high-pressure liquid storage device 14, where the energy is stably sealed as pressure energy. During energy release, the high-pressure liquid carbon dioxide absorbs heat in the evaporator, breaking through the phase change critical point and evaporating into a high-pressure gas state, releasing the stored pressure energy to power the turbine.

[0058] This invention achieves efficient energy conversion and storage by regulating the phase change of carbon dioxide. During energy storage, the compressed gas is converted into a high-pressure liquid state to store energy; during energy release, the liquid state evaporates to drive power generation. This mechanism, combined with heat recovery and waste energy utilization, improves energy efficiency and economics.

[0059] In some embodiments, please refer to Figure 1 The carbon dioxide pipeline between the compressor unit 12 and the first condenser 13, and the carbon dioxide pipeline between the high-pressure liquid storage device 14 and the first evaporator 15, are connected to heat exchangers. The steps for the high-pressure gaseous carbon dioxide before entering the first condenser 13 include: releasing the heat of compression through the heat exchanger, transferring the heat of compression to the high-pressure liquid carbon dioxide in the first evaporator 15 to replenish the heating energy of the high-pressure liquid carbon dioxide in the first evaporator 15; simultaneously, the temperature of the high-pressure gaseous carbon dioxide decreases after heat release through the heat exchanger, and it then enters the first condenser 13 for condensation.

[0060] In practice, the high-temperature, high-pressure gaseous carbon dioxide (carrying a large amount of compression heat) output by the compressor unit 12 flows through the high-temperature side of the heat exchanger before entering the first condenser 13, releasing the compression heat; at the same time, the high-pressure liquid carbon dioxide to be evaporated output by the high-pressure liquid storage device 14 flows through the low-temperature side of the heat exchanger, absorbing the released compression heat.

[0061] This process achieves dual optimization: on the one hand, the high-pressure liquid carbon dioxide absorbs the heat of compression and preheats, reducing the demand of the first evaporator 15 on external heat sources such as the waste heat 151 from the ethylene process, thus improving evaporation efficiency; on the other hand, the high-temperature, high-pressure gaseous carbon dioxide releases heat, reducing the amount of residual heat required to enter the first condenser 13, thereby reducing the consumption of external cold sources. Through the targeted recovery and cascade utilization of the heat of compression, the system avoids energy waste and enhances the stability of the condensation and evaporation cycles by stabilizing medium temperature fluctuations, significantly improving overall energy utilization efficiency and operational economy.

[0062] 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 by, include: The power generation module includes a carbon dioxide pipeline, and a low-pressure gas storage device, a compressor unit, a first condenser, a high-pressure liquid storage device, a first evaporator, and a turbine 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 sends 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 sends it to the turbine unit to generate electricity. The carbon dioxide pipeline and / or the low-pressure gas storage device are provided with a replenishment interface for receiving external carbon dioxide. The low-pressure gas storage device and / or the high-pressure liquid storage device are provided with a release interface for releasing carbon dioxide to the outside. A carbon dioxide capture device, wherein the inlet of the carbon dioxide capture device is connected to the carbon dioxide emission source of the refining and chemical process, and the outlet of the carbon dioxide capture device is connected to the replenishment interface; the capture device includes a purification component, which is used to remove impurities from the externally input carbon dioxide. The low-pressure gas storage device and the high-pressure liquid storage device are each equipped with a pressure sensor. The carbon dioxide capture device is electrically connected to the low-pressure gas storage device and the high-pressure liquid storage device and is connected to a controller. The controller adjusts the operating power of the carbon dioxide capture device according to the pressure signal from the pressure sensor. The carbon dioxide pipeline between the compressor unit and the first condenser, and the carbon dioxide pipeline between the high-pressure liquid storage device and the first evaporator, are connected through a heat exchanger for heat exchange.

2. The gas-liquid interconversion carbon dioxide compression energy storage system according to claim 1, characterized in that, The carbon dioxide pipeline between the low-pressure gas storage device and the compressor unit is provided with the supplementary interface; and / or, the carbon dioxide pipeline between the low-pressure gas storage device and the turbine unit is provided with the supplementary interface.

3. The gas-liquid interconversion carbon dioxide compression energy storage system of claim 1, wherein, The first condenser uses room temperature condensate as a cold source.

4. The gas-liquid interconversion carbon dioxide compression energy storage system of claim 1, wherein, The first evaporator uses waste heat from the ethylene process as a heat source.

5. A method for utilizing system compression heat, characterized by, Based on the gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 1, the method for utilizing the compression heat of the system includes: The compressor unit compresses low-pressure gaseous carbon dioxide to form high-pressure gaseous carbon dioxide; The high-pressure gaseous carbon dioxide enters the first condenser and is condensed into high-pressure liquid carbon dioxide before being stored in the high-pressure liquid storage device. The first evaporator heats the high-pressure liquid carbon dioxide in the high-pressure liquid storage device, causing the liquid carbon dioxide to evaporate into gaseous carbon dioxide, which then drives the turbine unit to generate electricity.

6. The system compression heat utilization method of claim 5, wherein, The carbon dioxide pipeline between the compressor unit and the first condenser, and the carbon dioxide pipeline between the high-pressure liquid storage device and the first evaporator, are connected to a heat exchanger; the steps for the high-pressure gaseous carbon dioxide before entering the first condenser include: The heat exchanger releases the heat of compression, which is then transferred to the high-pressure liquid carbon dioxide in the first evaporator to supplement the heating energy of the first evaporator for the high-pressure liquid carbon dioxide. At the same time, the temperature of the high-pressure gaseous carbon dioxide decreases after the heat is released by the heat exchanger, and it then enters the first condenser for condensation.

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