Gas-liquid mutual conversion compressed carbon dioxide energy storage system and method for utilizing compression heat of system

Abstract

The invention provides a gas-liquid mutual conversion compressed carbon dioxide energy storage system and a utilization method of system compression heat, and relates to the field of compressed carbon dioxide energy storage. The gas-liquid mutual conversion compressed carbon dioxide energy storage system comprises a power generation module, wherein the module comprises 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 which are arranged in sequence. The first condenser is used for condensing the compressed high-pressure gaseous carbon dioxide into liquid carbon dioxide and storing the liquid carbon dioxide in the high-pressure liquid storage device; the first evaporator heats liquid carbon dioxide to be gaseous and then sends the gaseous carbon dioxide to the turbine unit for power generation. The second condenser condenses the acting carbon dioxide into a liquid state; and the second evaporator heats the liquid carbon dioxide in the low-pressure liquid storage device into a gas state. A liquid storage mode is adopted, compared with gaseous storage, the storage space and the occupied area of the system can be remarkably reduced, the construction cost is reduced, and flexible deployment is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of compressed carbon dioxide energy storage, in particular to a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing system compression heat. BACKGROUND

[0002] Renewable energy grid connection affects the stability of the power grid due to its intermittency and volatility, and measures need to be taken to address it. Carbon dioxide energy storage technology has become a research hotspot due to its environmental safety, volatility mitigation, high energy density, and low environmental risk.

[0003] However, in the existing technical system, there are still some problems to be solved. For example, the gas warehouse in the system for storing low-pressure gaseous carbon dioxide results in a very large space required for overall construction. This not only increases the project land area, but also increases the construction and maintenance costs, thereby limiting the further popularization and application of the technology. SUMMARY

[0004] Therefore, the present application provides a gas-liquid interconversion compressed carbon dioxide energy storage system and a method for utilizing system compression heat, aiming to reduce the construction space of the gas-liquid interconversion compressed carbon dioxide energy storage system.

[0005] The technical solution of the present application is as follows: The present application provides a gas-liquid interconversion compressed carbon dioxide energy storage system, comprising a power generation module; the power generation module comprises 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 set arranged in the carbon dioxide pipeline in sequence; the first condenser is used for receiving high-pressure gaseous carbon dioxide compressed by the compressor set, and condensing the high-pressure gaseous carbon dioxide into liquid carbon dioxide, and delivering the liquid carbon dioxide to the high-pressure liquid storage device for storage; the first evaporator is used for receiving liquid carbon dioxide output by the high-pressure liquid storage device, heating the liquid carbon dioxide into gaseous carbon dioxide, and then introducing the gaseous carbon dioxide into the turbine unit to generate power; wherein the second condenser is used for condensing carbon dioxide after work of the turbine unit into liquid carbon dioxide; and the second evaporator is used for heating liquid carbon dioxide output by the low-pressure liquid storage device into gaseous carbon dioxide.

[0006] In an embodiment, the first condenser uses first ethylene process waste cold as a cold source, and the second condenser uses second ethylene process waste cold as a cold source.

[0007] In an embodiment, the first evaporator uses first ethylene process waste heat as a heat source, and the second evaporator uses second ethylene process waste heat as a heat source.

[0008] In an embodiment, a supplementary interface is arranged in the carbon dioxide pipeline between the turbine unit and the second condenser; and / or, a supplementary interface is arranged in the carbon dioxide pipeline between the second evaporator and the compressor unit.

[0009] In an embodiment, a carbon dioxide capturing device is further included, which is communicated between the supplementary interface and a carbon dioxide emission source in the outside world.

[0010] In an embodiment, a first delivery pump is arranged between the second condenser and the low-pressure liquid storage device; and / or, a second delivery pump is arranged between the low-pressure liquid storage device and the second evaporator.

[0011] In an embodiment, an energy storage module, a heat absorption device and a heat release device are further included; the energy storage module includes an energy storage pipeline, and a low-temperature storage tank and a high-temperature storage tank arranged in the energy storage pipeline; the heat absorption device is arranged in the carbon dioxide pipeline between the compressor unit and the first condenser, so as to introduce 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 arranged in the carbon dioxide pipeline between the first evaporator and the turbine unit, so as to introduce 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.

[0012] In an embodiment, the medium in the energy storage pipeline is pressurized water or heat-conducting oil.

[0013] In an embodiment, the energy storage system further includes a heat supply branch and a heat supply storage tank, one end of the heat supply 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 heat supply storage tank; the outlet of the heat supply storage tank is connected to an external heat user.

[0014] The application also provides a system compression heat utilization method based on the above-mentioned gas-liquid mutual conversion compression carbon dioxide energy storage system, the system compression heat utilization method comprising an energy storage step and an energy release step; the energy storage step comprising: the compressor group compressing gaseous carbon dioxide output by the second evaporator into high-pressure gaseous carbon dioxide; the energy storage pipeline being conducted, low-temperature medium in the low-temperature storage tank flowing into the heat absorption device, the low-temperature medium and the high-pressure gaseous carbon dioxide performing heat exchange in the heat absorption device to absorb heat, the low-temperature medium after heat absorption being warmed to form high-temperature medium and being transported to the high-temperature storage tank for storage; the high-pressure gaseous carbon dioxide after heat release in the heat absorption device flowing into the first condenser, being condensed into liquid carbon dioxide by the first condenser and being transported to the high-pressure liquid storage device for storage; the energy release step comprising: liquid carbon dioxide in the high-pressure liquid storage device flowing into the first evaporator and being heated into gaseous carbon dioxide; the energy storage pipeline being conducted, high-temperature medium in the high-temperature storage tank flowing into the heat release device, the high-temperature medium and the gaseous carbon dioxide performing heat exchange in the heat release device to release heat, the high-temperature medium after heat release being cooled to form low-temperature medium and flowing back to the low-temperature storage tank; the gaseous carbon dioxide after heat absorption being introduced into the turbine group to drive the turbine group to generate electricity.

[0015] The embodiment of the application provides a gas-liquid mutual conversion compression carbon dioxide energy storage system, which adopts a liquid carbon dioxide storage mode, can significantly reduce the space requirement of a storage device compared with a traditional gaseous storage, because the volume of liquid carbon dioxide is much smaller than that of gaseous carbon dioxide under the same mass. The design optimization makes the structure of the whole energy storage system more compact, effectively reduces the land occupation of the project, reduces the construction cost, and also provides the possibility for flexible deployment of the system in different scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without creative labor.

[0017] Figure 1 The overall schematic diagram of the gas-liquid mutual conversion compression carbon dioxide energy storage system provided by the application is shown in the figure.

[0018] Explanation of reference signs: 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, heat supply storage tank. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0020] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0021] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B are satisfied at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection claimed by the present application.

[0022] Renewable energy grid-connected affects the stability of the power grid due to its intermittency and volatility, and measures need to be taken to address it. Carbon dioxide energy storage technology has become a research hotspot due to its environmental safety, mitigation of fluctuations, high energy density, and low environmental risk. However, there are still some problems to be solved in the existing technical system. For example, the structure design for storing carbon dioxide in the system is not scientific and reasonable, resulting in a very large space required for the overall construction. This not only increases the project area, but also increases the construction and maintenance costs, thereby limiting the further promotion and application of the technology.

[0023] Therefore, the present application provides a gas-liquid interconversion compression carbon dioxide energy storage system and a method for utilizing system compression heat, aiming to reduce the construction space of the gas-liquid interconversion compression carbon dioxide energy storage system.

[0024] Please refer to Figure 1 The gas-liquid interconversion compression carbon dioxide energy storage system includes a power generation module 1. The power generation module 1 includes a carbon dioxide pipeline, and 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 arranged in the carbon dioxide pipeline in sequence. Among them, the first condenser 13 is used to receive high-pressure gaseous carbon dioxide compressed by the compressor unit 12, and condense 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 by the high-pressure liquid storage device 14, heats it to change it into gaseous carbon dioxide, and then enters the turbine unit 16 to drive the turbine unit 16 to generate electricity. At the same time, the function of the second condenser 17 is to condense the carbon dioxide after doing work in the turbine unit 16 into liquid carbon dioxide for storage in the low-pressure liquid storage device; and the second evaporator 18 is used to heat the liquid carbon dioxide output by the low-pressure liquid storage device 11 into gaseous carbon dioxide for re-compression by the compressor unit 12.

[0025] During system operation, compared with the traditional gaseous storage, the liquid carbon dioxide storage mode can significantly reduce the space requirement of the storage device, because the volume of liquid carbon dioxide is much smaller than that of gaseous carbon dioxide under the same mass. This design optimization makes the structure of the entire energy storage system more compact, effectively reduces the project area, reduces the construction cost, and also provides the possibility for flexible deployment of the system in different scenarios.

[0026] Therefore, the present application effectively solves the problem of large storage device space in the traditional carbon dioxide energy storage system through the design of liquid storage.

[0027] The gas-liquid interconversion working mode fully utilizes the phase change characteristics of carbon dioxide under different pressure and temperature conditions, and realizes efficient storage and release of energy.

[0028] In some embodiments, the first condenser 13 uses first ethylene process waste cold 131 as a cold source, and the second condenser 17 uses second ethylene process waste cold 171 as a cold source. The "ethylene process waste cold" can be understood as a cold resource with a relatively low temperature and not fully utilized in the ethylene production process, such as the discharge cold of the propylene refrigeration system in the ethylene cracking gas separation stage, the cold energy released in the liquefied natural gas (LNG) gasification process, etc.; for example, the ethylene process waste cold can be methane in the ethylene process, and the temperature of the methane is about -160°C to 0°C.

[0029] In a specific implementation, the first condenser 13 establishes an independent heat exchange circuit with the low-temperature methane pipeline of the ethylene process system, the high-pressure gaseous carbon dioxide flows in the shell side of the condenser, and the low-temperature methane flows in the tube side in a reverse direction, and the heat exchange is strengthened by high-efficiency finned tubes; the second condenser 17 is connected to the low-pressure stage circuit of the propylene refrigeration system of the ethylene process, and the low-pressure gaseous carbon dioxide discharged by the turbine unit 16 is condensed into a liquid state by using the evaporation cold of the propylene at 0°C to -40°C, and the two condensers are respectively adapted to the ethylene process waste cold resources in different temperature zones, so as to realize the cascade recovery and utilization of cold energy.

[0030] The embodiment of the present application integrates the waste cold of the ethylene process, replaces the traditional external cold source, reduces the dependence of the energy storage system on additional energy, realizes the cascade utilization of industrial waste energy, and significantly improves the comprehensive energy efficiency and economy of the system.

[0031] In some embodiments, please refer to Figure 1 , the first evaporator 15 uses first ethylene process waste heat 151 as a heat source, and the heat source of the second evaporator 18 uses second ethylene process waste heat 181 as a heat source. The "ethylene process waste heat" refers to the waste heat generated in the cracking reaction, compression, separation, etc. of the ethylene process device, such as the flue gas waste heat of the cracking furnace, the steam waste heat of the quenching boiler, the inter-stage cooling waste heat of the compressor unit 12, etc.; for example, the ethylene process waste heat can be quenching water in the ethylene process, and the quenching water is about 50°C.

[0032] In implementation, the first evaporator 15 is connected with the quench water system of the ethylene process, and the waste heat of the quench water at about 50 DEG C is used as the heat source: the high-pressure liquid carbon dioxide output by the high-pressure storage device 14 is reduced in pressure by a throttle valve and then enters the tube side of the first evaporator 15, and forced convection heat exchange is performed with the quench water circulating in the shell side, and the high-pressure liquid carbon dioxide is vaporized into medium-pressure gaseous carbon dioxide after absorbing the waste heat released by the quench water at 50 DEG C, and the pressure is controlled at 8-12 MPa to meet the inlet parameter requirements of the turbine unit 16; the temperature of the quench water after heat exchange is reduced to about 40 DEG C and returned to the quench system of the ethylene process to continue participating in the cooling cycle of the cracking gas. The second evaporator 18 is connected with the flue gas waste heat recovery system of the ethylene process device, and the waste heat of the flue gas at 150-200 DEG C is used as the heat source: the liquid carbon dioxide in the low-pressure storage device 11 is pressurized by a pump to 2-3 MPa and then enters the second evaporator 18, and heat exchange is performed with the flue gas in the finned tube heat exchanger, and the low-pressure liquid carbon dioxide is vaporized into low-pressure gaseous carbon dioxide after absorbing heat, and then enters the compressor unit 12 for multi-stage compression; the temperature of the flue gas after heat exchange is reduced to below 100 DEG C, and the flue gas can be further used for preheating boiler feed water or heating process medium, so that the cascade utilization of waste heat is realized.

[0033] In the embodiments of the present application, by integrating the waste heat of the ethylene process, the first evaporator 15 and the second evaporator 18 are coupled with different temperature waste heat resources of the ethylene process respectively, so that a gradient utilization chain from low-temperature waste heat to medium-temperature waste heat is formed, which not only avoids the problem of low evaporation efficiency caused by insufficient temperature of a single heat source, but also maximizes the recovery of industrial waste heat.

[0034] In some embodiments, referring to Figure 1 , a supplementary interface is arranged in the carbon dioxide pipeline between the turbine unit 16 and the second condenser 17; and / or, a supplementary interface is arranged in the carbon dioxide pipeline between the second evaporator 18 and the compressor unit 12; which is a further optimization of the stability and adaptability of the gas-liquid conversion and compression carbon dioxide energy storage system, and the core function is to supplement the carbon dioxide working medium for the system to cope with the working medium loss or working condition adjustment demand in long-term operation.

[0035] During system operation, although the sealing of pipelines and equipment has been optimized, long-term high-frequency gas-liquid conversion and pressure fluctuations may cause trace amounts of carbon dioxide to leak. If the total amount of working medium continues to decrease, it will directly affect the intake of the compressor set 12 and the efficiency of the turbine set 16, and even disrupt the balance of the cycle. The replenishment interface can replenish the working medium through an external gas source: in the pipeline between the turbine set 16 and the second condenser 17, the carbon dioxide is in a low-pressure gaseous state (or a gas-liquid mixed state) after being subjected to turbine work. Replenishment at this point 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 the compressor set 12, the carbon dioxide is in a low-pressure gaseous state and is about to enter the compressor set 12. Replenishment of gaseous working medium at this point can directly meet the intake requirements of the compressor set 12, avoiding damage caused by “liquid hammer” from liquid working medium, and ensuring the stability of the compression link.

[0036] In some embodiments, referring to Figure 1 , the gas-liquid conversion compression carbon dioxide energy storage system further comprises a carbon dioxide capture device 5, which is connected between the replenishment interface and a carbon dioxide emission source outside.

[0037] The addition of the carbon dioxide capture device 5, which is connected between the replenishment interface and the carbon dioxide emission source outside, in the gas-liquid conversion compression carbon dioxide energy storage system can not only continuously replenish the working medium for the system by capturing and purifying carbon dioxide from the emission source, thereby reducing the cost of the working medium and ensuring the stability of the cycle, but also realize the resource utilization of greenhouse gases to reduce carbon emissions, forming a “capture-energy storage” synergistic effect and improving the comprehensive value of the system in environmental protection and energy utilization.

[0038] In some embodiments, referring to Figure 1 , a first delivery pump is arranged between the second condenser 17 and the low-pressure liquid storage device 11; and / or a second delivery pump is arranged between the low-pressure liquid storage device 11 and the second evaporator 18.

[0039] The first delivery pump is arranged between the second condenser 17 and the low-pressure liquid storage device 11, and the second delivery pump is arranged between the low-pressure liquid storage device 11 and the second evaporator 18, to enhance the stability of the delivery of liquid carbon dioxide in the low-pressure side cycle. The first delivery pump prevents liquid carbon dioxide from being unable to flow to the liquid storage device due to pressure or resistance, ensuring efficient storage and avoiding a decrease in condensation efficiency. The second delivery pump overcomes resistance or height differences, controls the amount of liquid working medium entering the evaporator, maintains the stability of the evaporation process, continuously supplies gas to the compressor set 12, and prevents fluctuations in compression efficiency. The arrangement of the two pumps improves the controllability of the delivery of liquid working medium, optimizes the smoothness of the low-pressure side cycle, and improves the stability and efficiency of the system operation.

[0040] In some embodiments, referring to Figure 1, in order to better adapt to the fluctuation of power demand, the gas-liquid conversion carbon dioxide energy storage system is further provided with an energy storage module 2, an endothermic device 3 and an exothermic device 4. The energy storage module 2 comprises an energy storage pipeline, a low-temperature storage tank 21 and a high-temperature storage tank 22 arranged in the energy storage pipeline. The endothermic device 3 is arranged on the carbon dioxide pipeline between the compressor set 12 and the first condenser 13, and can introduce the low-temperature medium in the low-temperature storage tank 21 through the energy storage pipeline and exchange heat with the carbon dioxide compressed by the compressor set 12 in the carbon dioxide pipeline; the exothermic device 4 is arranged on the carbon dioxide pipeline between the first evaporator 15 and the turbine set 16, and can introduce the high-temperature medium in the high-temperature storage tank 22 through the energy storage pipeline and exchange heat with the carbon dioxide to be introduced into the turbine set 16 in the carbon dioxide pipeline.

[0041] In specific implementation, the energy storage module 2 forms an independent cold-heat circulation loop through the energy storage pipeline, the low-temperature storage tank 21 and the high-temperature storage tank 22 store low-temperature medium (such as low-temperature heat conducting oil, anti-freezing liquid) and high-temperature medium (such as high-temperature heat conducting oil, molten salt) respectively, and the compression heat is temporarily stored and utilized in stages.

[0042] In the energy storage stage (when the power grid load is at a low point or renewable energy is excessive), the compressor set 12 compresses the low-pressure gaseous carbon dioxide into high-temperature and high-pressure gaseous carbon dioxide, and at this time the endothermic device 3 is started: the low-temperature medium in the low-temperature storage tank 21 is pumped into the endothermic device 3 through the energy storage pipeline and exchanges heat with the high-temperature and high-pressure gaseous carbon dioxide just completed compression in the carbon dioxide pipeline. After absorbing the compression heat, the low-temperature medium is raised in temperature and becomes high-temperature medium and is transported to the high-temperature storage tank 22 for storage; and the high-pressure gaseous carbon dioxide lowered in temperature after heat exchange enters the first condenser 13 and is more easily condensed into high-pressure liquid carbon dioxide, reducing the cold source consumption of the first condenser 13.

[0043] In the energy release stage (when the power grid load is at a peak or power demand surges), the gaseous carbon dioxide output by the first evaporator 15 needs to be further raised in parameter to enhance the power generation power of the turbine set 16, and at this time the exothermic device 4 is started: the high-temperature medium in the high-temperature storage tank 22 is pumped into the exothermic device 4 through the energy storage pipeline and exchanges heat with the gaseous carbon dioxide to be introduced into the turbine set 16, releases the stored compression heat to heat the carbon dioxide, so that the temperature and pressure of the carbon dioxide are further raised, and the turbine working efficiency is improved; the high-temperature medium after heat release is lowered in temperature to become low-temperature medium and flows back to the low-temperature storage tank 21 to complete the cycle.

[0044] Through the arrangement of the energy storage module 2, the endothermic device 3 and the exothermic device 4, the storage and release of the compression heat can be flexibly adjusted according to the fluctuation of power demand: more heat storage when the power demand is low and more heat release when the power demand is high, which not only avoids the waste of compression heat, but also dynamically matches the power generation power of the turbine set 16, significantly improving the adaptability of the system to power fluctuation.

[0045] In some embodiments, please refer toFigure 1 In order to improve the compression efficiency of carbon dioxide and reduce the energy consumption of the system, specifically, the compressor set 12 includes a first compressor 121 and a second compressor 122 connected in series, and the second compressor 122 is closer to the high-pressure liquid storage device 14 than the first compressor 121 along the direction of the carbon dioxide pipe; the heat absorption device 3 includes a first heat exchanger 31 and a second heat exchanger 32, the first heat exchanger 31 is arranged on the carbon dioxide pipe between the first compressor 121 and the second compressor 122, and the second heat exchanger is arranged on the carbon dioxide pipe between the second compressor 122 and the high-pressure liquid storage device 14.

[0046] The specific implementation principle is: during the energy storage process, when the gaseous carbon dioxide flows through the first compressor 121 and the second compressor 122 for staged compression in sequence, the temperature of the gaseous carbon dioxide will gradually increase. The first heat exchanger 31 first exchanges heat with the carbon dioxide compressed by the first compressor 121, absorbs part of the compression heat and stores it in the high-temperature storage tank 22, reduces the temperature of the carbon dioxide entering the second compressor 122, and avoids the increase of power consumption of the second compressor 122 due to too high temperature; the second heat exchanger 32 exchanges heat with the high-temperature and high-pressure carbon dioxide at the outlet of the second compressor 122, further recovers the compression heat, and reduces the temperature of the carbon dioxide to be closer to the condensation temperature, improves the condensation efficiency of the first condenser 13, and reduces the energy loss in the condensation process. Through the synergistic effect of two-stage compression and two-stage heat exchange, not only the compression efficiency of carbon dioxide is improved, but also the compression heat generated in different compression stages is maximized, which provides sufficient heat energy support for the efficient operation of the turbine set 16 in the subsequent energy release process, and effectively reduces the overall energy consumption of the system.

[0047] In some embodiments, please refer to Figure 1 In order to realize the cascade release of carbon dioxide energy and improve the power generation efficiency of the turbine set 16, specifically, the turbine set 16 includes a first turbine 161 and a second turbine 162 connected in series, and the second turbine 162 is closer to the high-pressure liquid storage device 14 than the first turbine 161 along the direction of the carbon dioxide pipe; the heat release device 4 includes a third heat exchanger 41 and a fourth heat exchanger 42, the third heat exchanger 41 is arranged on the carbon dioxide pipe between the first evaporator 15 and the first turbine 161, and the fourth heat exchanger 42 is arranged on the carbon dioxide pipe between the first turbine 161 and the second turbine 162.

[0048] The specific implementation principle is that in the energy release process, the liquid carbon dioxide output by 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 it, so that the carbon dioxide obtains initial kinetic energy and reaches the optimal inlet parameter of the first turbine 161, and drives the first turbine 161 to perform preliminary work to generate electricity; the medium-pressure gaseous carbon dioxide discharged from the first turbine 161 then enters the fourth heat exchanger 42, and is heat-exchanged with another part of the high-temperature medium output by the high-temperature storage tank 22, so as to further increase the temperature and pressure to meet the inlet requirement of the second turbine 162, and drive the second turbine 162 to perform secondary work to generate electricity. Through the combined design of two-stage turbine and two-stage heat exchanger, the cascade release of carbon dioxide energy is realized, the loss caused by the one-time release of energy in the single-stage turbine is avoided, the cascade utilization of high-temperature medium also improves the heat energy conversion efficiency, and the overall power generation of the turbine set 16 and the energy utilization rate are significantly improved.

[0049] In some embodiments, referring to Figure 1 , the medium in the energy storage pipeline is pressurized water or heat conducting oil.

[0050] In the specific implementation process, the circulation of pressurized water or heat conducting oil builds a heat storage and release closed loop, so as to reduce the system energy loss and improve the efficiency. Specifically, in the system energy storage stage (when the compressor set 12 is working), the carbon dioxide compressed by the compressor set 12 is in a high-temperature and high-pressure state, at this time the heat absorption device 3 is started: the pressurized water or heat conducting oil stored in the low-temperature storage tank 21 is introduced into the heat absorption device 3 through the energy storage pipeline, and heat-exchanged with the high-temperature and high-pressure carbon dioxide to absorb a large amount of heat generated in the compression process, and then transported to the high-temperature storage tank 22 through the energy storage pipeline for storage, so as to complete the recovery of the compression heat and avoid the waste caused by the direct dissipation of the heat through the first condenser 13; in the system energy release stage (when the turbine set 16 generates electricity), the liquid carbon dioxide output by the high-pressure liquid storage device 14 is gasified through the first evaporator 15, and needs to be further boosted to enhance the turbine work capacity, at this time the heat release device 4 is started: the pressurized water or heat conducting oil stored in the high-temperature storage tank 22 is introduced into the heat release device 4 through the energy storage pipeline, and heat-exchanged with the gaseous carbon dioxide to be introduced into the turbine set 16 to release the stored heat to the carbon dioxide, so as to further increase the temperature and enthalpy of the carbon dioxide, thereby realizing more efficient energy conversion in the turbine set 16; the pressurized water or heat conducting oil after heat release is cooled and then flows back to the low-temperature storage tank 21 through the energy storage pipeline, so as to complete the medium circulation and prepare for the heat absorption process in the next energy storage stage. The whole process realizes the temporary storage of heat through the energy storage module 2, and the heat absorption and heat release device 4 cooperates to direct the compression heat which would otherwise be wasted to improve the work efficiency in the energy release stage, so as to form an internal circulation of energy.

[0051] In some embodiments, please refer to Figure 1 In order to expand the utilization scenarios of the system and realize diversified output of energy, the energy storage system further comprises a heat supply branch and a heat supply storage tank 23. One end of the heat supply 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 heat supply storage tank 23. The outlet of the heat supply storage tank 23 is connected to an external heat user.

[0052] During the energy storage process, part of the high-temperature medium absorbed by the heat absorption device 3 from the compressed carbon dioxide can be introduced into the heat supply storage tank 23 through the heat supply branch for storage. When an external heat user such as an industrial production or a heating system has a heat energy demand, the heat supply storage tank 23 can output high-temperature liquid to realize heat energy supply in addition to power generation function, thereby improving the energy comprehensive utilization efficiency.

[0053] The embodiment of the present application also provides a system compression heat utilization method based on the carbon dioxide energy storage system provided by any of the above embodiments. Please refer to Figure 1 The system compression heat utilization method comprises an energy storage step and an energy release step.

[0054] The energy storage step comprises: the compressor set 12 compresses the gaseous carbon dioxide in the second evaporator 18 into high-pressure gaseous carbon dioxide; the energy storage pipeline is conducted, the low-temperature medium in the low-temperature storage tank 21 flows into the heat absorption device 3, the low-temperature medium exchanges heat with the high-pressure gaseous carbon dioxide in the heat absorption device 3 to absorb heat, the low-temperature medium after heat absorption is warmed to form high-temperature medium and is transported to the high-temperature storage tank 22 for storage; the high-pressure gaseous carbon dioxide after heat release in the heat absorption device 3 flows into the first condenser 13, is condensed into liquid carbon dioxide by the first condenser 13, and is transported to the high-pressure liquid storage device 14 for storage. The energy release step comprises: the 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 conducted, the high-temperature medium in the high-temperature storage tank 22 flows into the heat release device 4, the high-temperature medium exchanges heat with the gaseous carbon dioxide in the heat release device 4 to release heat, the high-temperature medium after heat release is cooled to form low-temperature medium and flows back to the low-temperature storage tank 21; the gaseous carbon dioxide after heat absorption is introduced into the turbine set 16 to drive the turbine set 16 to generate electricity.

[0055] The specific implementation is that: when there is excess electricity, the compressor set 12 adjusts the compression strength according to the grid load, and the heat absorption device 3 recovers the compression heat and converts it into high-temperature medium for storage. When there is a power shortage, the high-temperature storage tank 22 releases the high-temperature medium as needed, the heat release device 4 adjusts the carbon dioxide parameters to adapt to the change of power generation demand, and the power of the turbine set 16 is quickly adjusted.

[0056] The embodiment of the present application realizes the collaborative conversion and efficient utilization of heat energy and electric energy generated in the carbon dioxide compression process through the above-mentioned compression heat utilization method.

[0057] The above merely illustrates the embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields, or the like, which is made under the technical concept of the present application, and based on the content of the present application specification and drawings, is included in the patent protection scope of the present application.

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.

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, The carbon dioxide pipeline between the turbine unit and the second condenser is provided with a supplementary interface; and / or, A supplementary interface is provided for the carbon dioxide pipeline between the second evaporator and the compressor unit.

5. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 4, characterized in that, It also includes a carbon dioxide capture device, which is connected to the supplemental interface and an external carbon dioxide emission source.

6. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 1, characterized in that, A first transfer pump is provided between the second condenser and the low-pressure liquid storage device; and / or, A second delivery pump is provided between the low-pressure liquid storage device and the second evaporator.

7. 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.

8. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 7, characterized in that, The medium in the energy storage pipeline is pressurized water or heat transfer oil.

9. The gas-liquid interconversion compressed carbon dioxide energy storage system according to claim 7, 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.

10. 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 7, 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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