A compressed carbon dioxide energy storage system and method combined with air separation technology

Abstract

The present invention belongs to the field of energy storage technology, and specifically discloses a compressed carbon dioxide energy storage system and method combined with air separation technology. The system includes an air separation unit for separating air to generate nitrogen, oxygen, carbon dioxide, and waste nitrogen; an energy storage unit uses carbon dioxide as the working medium of the energy storage unit. During the low electricity consumption period, carbon dioxide is compressed, and the heat energy and pressure energy generated during the process of collecting compressed carbon dioxide are collected; the energy release unit converts the heat energy and pressure energy collected by the energy storage into electrical energy during the high electricity consumption period and supplies it to the air separation unit and electrical equipment; among them, the waste nitrogen is used as the heat source of the air separation unit, the energy storage unit, and the energy release unit to provide heat, and nitrogen / oxygen is used as the cold source of the air separation unit, the energy storage unit, and the energy release unit to provide cold. The present invention reduces the power consumption and operating costs, improves the system efficiency, and has the advantages of high energy conversion efficiency and high resource utilization rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a compressed carbon dioxide energy storage system and method combined with air separation technology. Background Art

[0002] With the rapid development of renewable energy, the power system is facing the challenge of how to efficiently store and utilize energy. As a new type of energy storage technology, the compressed carbon dioxide energy storage system can convert electrical energy into internal energy during periods of excess power supply, compress and store it by means of a carbon dioxide medium, and release the stored energy during peak power demand.

[0003] However, in order to improve the overall energy storage density of the current compressed carbon dioxide energy storage system, it is usually necessary to convert gaseous carbon dioxide into liquid for storage, and additional heat sources and cold sources are also required. A large amount of electrical energy and other energy is usually consumed in this conversion process, resulting in a high operating cost of the compressed carbon dioxide energy storage system and a low overall energy conversion efficiency of the system. Summary of the Invention

[0004] The purpose of the present invention is to provide a compressed carbon dioxide energy storage system and method combined with air separation technology. The entire system does not require additional heat sources and cold sources, reduces power consumption, improves system efficiency, reduces operating costs, and has the advantages of high energy conversion efficiency and high resource utilization rate.

[0005] To achieve the above technical objectives, the specific technical solutions of the present invention are as follows:

[0006] A compressed carbon dioxide energy storage system combined with air separation technology, comprising:

[0007] A gaseous carbon dioxide storage tank, a liquid carbon dioxide storage tank, an energy storage unit, an energy release unit, and an air separation unit. The energy storage unit and the energy release unit are respectively arranged between the gaseous carbon dioxide storage tank and the liquid carbon dioxide storage tank. The energy storage unit includes a preheater, a second compressor, and a condenser connected in sequence. The second compressor is used to compress carbon dioxide, and the condenser is used to condense carbon dioxide. The energy release unit includes a second evaporator, a second turbine, and a second cooler connected in sequence. The output shaft of the second turbine is connected to the input shaft of a generator, and the generator is used to generate electrical energy. The second cooler is used to cool the carbon dioxide entering the gaseous carbon dioxide storage tank. The air separation unit includes an air pretreatment component and a separation tower. The separation tower is connected to the output end of the air pretreatment component, and the separation tower is used to separate air to produce nitrogen, oxygen, and waste nitrogen. The nitrogen and oxygen are cold sources, and the waste nitrogen is a heat source;

[0008] Among them, the cold source is supplied to the condenser, the second cooler and the air pretreatment assembly through pipelines respectively, the heat source is supplied to the preheater and the second evaporator through pipelines respectively, and the electric energy generated by the generator is supplied to the air pretreatment assembly.

[0009] Preferably, the air pretreatment assembly includes a first compressor, a first cooler, a gas-liquid separator and a second expansion valve. The first compressor, the first cooler and the gas-liquid separator are connected. The gas-phase outlet of the gas-liquid separator is connected to the second expansion valve. The input end of the separation tower is connected to the second expansion valve. The first compressor is used to pressurize and heat the air. The first cooler is used to cool the air. The gas-liquid separator is used to separate liquid water and carbon dioxide from gaseous air. The second expansion valve expands and cools the gaseous air.

[0010] Among them, the cold source is connected to the cooling inlet of the first cooler through a pipeline. The cooling outlet of the first cooler is vented. The generator is electrically connected to the first compressor.

[0011] Preferably, the air pretreatment assembly further includes an air purifier and a first control valve. The air purifier is arranged at the air inlet of the first compressor. The air purifier is used to filter and remove impurities in the air. The first control valve is arranged at the air inlet of the air purifier. The first control valve is used to control the on-off of the air.

[0012] Preferably, it further includes a carbon dioxide supply assembly. The carbon dioxide supply assembly includes a dryer, a second control valve, a first expansion valve and a first evaporator connected in sequence. The dryer is connected to the liquid-phase outlet of the gas-liquid separator. The first evaporator is connected to the gaseous carbon dioxide storage tank.

[0013] Among them, the heat source is connected to the heating inlet of the first evaporator through a pipeline. The heating outlet of the first evaporator is vented.

[0014] Preferably, it further includes a carbon dioxide storage assembly. The carbon dioxide storage assembly includes a third control valve, a second booster pump and a carbon dioxide storage tank connected in sequence. The second booster pump is used to pressurize the liquid carbon dioxide. The third control valve is connected to the outlet of the dryer.

[0015] Preferably, it further includes a heat exchange unit. The heat exchange unit includes a cold storage tank, a first heat exchanger, a fourth heat exchanger and a heat storage tank. The first heat exchanger is arranged between the second compressor and the condenser. The fourth heat exchanger is arranged between the second evaporator and the second turbine. Heat storage media are provided in the cold storage tank and the heat storage tank. The cold storage tank and the heat storage tank form a heat exchange loop between the first heat exchanger and the fourth heat exchanger. The heat storage media can flow in the heat exchange loop.

[0016] Preferably, the energy storage unit further includes a third compressor and a second heat exchanger. The first heat exchanger, the third compressor, the second heat exchanger, and the condenser are connected in sequence. The second heat exchanger is respectively connected to the cold storage tank and the heat storage tank.

[0017] Preferably, the energy release unit further includes a third heat exchanger and a first turbine. The second evaporator, the third heat exchanger, the first turbine, and the fourth heat exchanger are connected in sequence. The third heat exchanger is respectively connected to the cold storage tank and the heat storage tank;

[0018] Wherein, the output shaft of the first turbine is connected to the input shaft of the generator. The generator is used to generate electric energy, and the generator is electrically connected to the first compressor.

[0019] A compressed carbon dioxide energy storage method, which is applied to the above-mentioned compressed carbon dioxide energy storage system combined with air separation technology, includes the following steps:

[0020] Use the air separation unit to separate air to generate nitrogen, oxygen, carbon dioxide, and waste nitrogen. Use the waste nitrogen as the heat source for the air separation unit, the energy storage unit, and the energy release unit respectively, use the nitrogen as the cold source for the air separation unit, the energy storage unit, and the energy release unit respectively, or use the oxygen as the cold source for the air separation unit, the energy storage unit, and the energy release unit respectively;

[0021] During the low electricity consumption period, the energy storage unit compresses carbon dioxide and collects the heat energy and pressure energy generated during the process of compressing carbon dioxide.

[0022] During the high electricity consumption period, the energy release unit converts the heat energy and pressure energy collected by the energy storage into electric energy and supplies it to the air separation unit and the electrical equipment.

[0023] Compared with the prior art, the compressed carbon dioxide energy storage system and method combined with air separation technology of the present invention has three different working units, namely an energy storage unit, an energy release unit, and an air separation unit. It generates a heat source and a cold source through the air separation unit, supplies them to the energy storage unit and the energy release unit respectively, and uses the electric energy converted after the energy storage and energy release process of the working medium to supply the air separation unit. The whole system does not need to introduce additional heat sources and cold sources. Moreover, since the electric energy generated by the energy release unit can be supplemented for use by the air separation unit, it does not require too much external electric energy input, reducing the overall consumption of electric energy and improving the system efficiency. In addition, due to the simple structure of the system, air is used as the object source for separation, which is easy to obtain and has a low cost, making the energy storage system no longer dependent on a specific geographical environment and can be applied in a wider geographical area. It has the advantages of less power consumption, high energy conversion efficiency, high resource utilization rate, and low operating cost, and is highly practical and worthy of promotion. Description of the Drawings

[0024] Figure 1 Schematic diagram of the overall structure of the present invention Figure 1 .

[0025] Figure 2 Schematic diagram of the structure of the air separation unit of the present invention.

[0026] Figure 3 Schematic diagram of the structure of the energy storage unit of the present invention Figure 1 .

[0027] Figure 4 Schematic diagram of the structure of the energy release unit of the present invention Figure 1 .

[0028] Figure 5 Schematic diagram of the structure of the energy storage unit of the present invention Figure 2 .

[0029] Figure 6 Schematic diagram of the structure of the energy release unit of the present invention Figure 2 .

[0030] Figure 7 Schematic diagram of the overall structure of the present invention Figure 2 .

[0031] Reference numerals:

[0032] 1, air purifier; 2, first compressor; 3, first cooler; 4, gas-liquid separator; 5, dryer; 6, first expansion valve; 7, first evaporator; 8, second expansion valve; 9, separation tower; 10, first booster pump; 11, argon storage tank; 12, second booster pump; 13, carbon dioxide storage tank; 14, gaseous carbon dioxide storage tank; 15, preheater; 16, second compressor; 17, first heat exchanger; 18, third compressor; 19, second heat exchanger; 20, condenser; 21, liquid carbon dioxide storage tank; 22, second evaporator; 23, third heat exchanger; 24, first turbine; 25, fourth heat exchanger; 26, second turbine; 27, second cooler; 28, cold storage tank; 29, heat storage tank; 30, first control valve; 31, second control valve; 32, third control valve; 33, fourth control valve; 34, fifth control valve; 35, sixth control valve; 36, seventh control valve; 37, eighth control valve. Detailed implementation manners

[0033] At present, in order to improve the overall energy storage density of the compressed carbon dioxide energy storage system, it is usually necessary to convert gaseous carbon dioxide into liquid for storage, and additional heat sources and cold sources are also required. A large amount of electric energy and other energy are usually consumed in this conversion process, resulting in a high operating cost of the compressed carbon dioxide energy storage system and a low overall energy conversion efficiency of the system.

[0034] In view of the above technical problems, the present invention provides a new compressed carbon dioxide energy storage system and method combined with air separation technology.

[0035] To enable those skilled in the art to better understand and implement the technical solution of the present invention, the technical solution in the present invention will be clearly and elaborately described below in conjunction with the attached Figures 1 to 7 , diagrams.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0037] In addition, it should be further noted that in the description of the embodiments of the present invention, unless otherwise specified, " / " means "or". For example, A / B can mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "a plurality" means two or more than two.

[0038] The following terms "first", "second", "third", "fourth" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third", "fourth" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more than two.

[0039] Embodiment 1

[0040] As Figure 1 shown, the present invention provides a compressed carbon dioxide energy storage system combined with air separation technology, including a gaseous carbon dioxide storage tank 14, a liquid carbon dioxide storage tank 21, an energy storage unit, an energy release unit, and an air separation unit. Among them, the gaseous carbon dioxide storage tank 14 is used to store gaseous carbon dioxide, and the liquid carbon dioxide storage tank 21 is used to store liquid carbon dioxide.

[0041] Specifically, as Figure 3As shown in the figure, the energy storage unit is arranged between the gaseous carbon dioxide storage tank 14 and the liquid carbon dioxide storage tank 21. It includes a preheater 15, a second compressor 16, and a condenser 20 that are connected in sequence. The second compressor 16 is used to compress carbon dioxide, and the condenser 20 is used to condense carbon dioxide. The preheater 15 is connected to the gaseous carbon dioxide storage tank 14 through a fifth control valve 34, and the condenser 20 is connected to the liquid carbon dioxide storage tank 21.

[0042] Specifically, as Figure 5 shown in the figure, the energy release unit is arranged between the gaseous carbon dioxide storage tank 14 and the liquid carbon dioxide storage tank 21. It includes a second evaporator 22, a second turbine 26, and a second cooler 27 that are connected in sequence. The output shaft of the second turbine 26 is connected to the input shaft of the generator. The generator is used to generate electric energy. The second cooler 27 is used to cool the carbon dioxide entering the gaseous carbon dioxide storage tank 14. The second evaporator 22 is connected to the liquid carbon dioxide storage tank 21 through a sixth control valve 35, and the second cooler 27 is connected to the gaseous carbon dioxide storage tank 14.

[0043] Specifically, the heat exchange unit includes a cold storage tank 28, a first heat exchanger 17, a fourth heat exchanger 25, and a heat storage tank 29. The first heat exchanger 17 is arranged between the second compressor 16 and the condenser 20. The fourth heat exchanger 25 is arranged between the second evaporator 22 and the second turbine 26. Heat storage media are provided in the cold storage tank 28 and the heat storage tank 29. The cold storage tank 28 and the heat storage tank 29 form a heat exchange loop between the first heat exchanger 17 and the fourth heat exchanger 25. The heat storage media can flow in the heat exchange loop, thereby realizing the entire heat cycle.

[0044] As Figure 2 shown in the figure, the air separation unit includes an air pretreatment assembly and a separation tower 9. The air pretreatment assembly separates air into a gas phase and a liquid phase. The separation tower 9 is connected to the gas phase output end of the air pretreatment assembly. The separation tower 9 is used to separate air to produce nitrogen, oxygen, and waste nitrogen. Nitrogen and oxygen are cold sources, and waste nitrogen is a heat source. Among them, the cold sources are supplied to the condenser 20, the second cooler 27, and the air pretreatment assembly through pipelines respectively. The heat source is supplied to the preheater 15 and the second evaporator 22 through pipelines respectively. The electric energy generated by the generator is supplied to the air pretreatment assembly.

[0045] Specifically, the structure of the air pretreatment component mainly includes a first compressor 2, a first cooler 3, a gas-liquid separator 4, and a second expansion valve 8. The first compressor 2, the first cooler 3, and the gas-liquid separator 4 are connected. The gas-phase outlet of the gas-liquid separator 4 is connected to the second expansion valve 8. The input end of the separation tower 9 is connected to the second expansion valve 8. The first compressor 2 is used to pressurize and heat the air. The first cooler 3 is used to convert the water vapor and carbon dioxide in the pressurized air into liquid and send them into the gas-liquid separator 4 for gas-liquid separation. The gas-liquid separator 4 is used to separate the liquid water and carbon dioxide from the gaseous air. The second expansion valve 8 expands and cools the gaseous air. Among them, the cold source is connected to the cooling inlet of the first cooler 3 through a pipeline, and the cooling outlet of the first cooler 3 is vented, so that the cold source is directly discharged into the air after cooling the first cooler 3. The generator is electrically connected to the first compressor 2, so as to supply the electric energy generated on the generator to the first compressor 2 for use, enabling the system to be self-sufficient and reducing external power supply.

[0046] Furthermore, in order to remove impurities in the air and improve the efficiency of pretreatment, an air purifier 1 and a first control valve 30 are added to the air pretreatment component. The air purifier 1 is arranged at the air inlet of the first compressor 2. The air purifier 1 is used to filter and remove impurities in the air. The first control valve 30 is arranged at the air inlet of the air purifier 1. The first control valve 30 is used to control the on-off of the air.

[0047] During use, the air at normal temperature and pressure is processed by the air pretreatment component into a gas phase and a liquid phase after pressurization and cooling. The gas phase is sent into the separation tower 9. Nitrogen, oxygen, and waste nitrogen are generated by separation in the separation tower 9. Nitrogen and oxygen are cold sources, and waste nitrogen is a heat source. The heat source and the cold source are respectively sent into the energy storage unit and the energy release unit, so that on the premise that the energy release unit and the energy storage unit work reliably, the electric energy generated on the generator is supplied to the air separation unit and the electrical equipment.

[0048] The energy storage unit, the energy release unit, and the air separation unit of the present invention can work independently to complete the storage of energy, the release of energy, and the separation of air respectively. They can also combine the energy release unit with the air separation unit, and use the electric energy generated in the energy release stage for air separation to realize the recycling of internal resources of the system. In addition, the system of the present invention can generate different components such as nitrogen, oxygen, and waste nitrogen through the air separation unit. Different components can be supplied to the required users as needed. The various gases generated by the air separation unit are recycled and converted into electric energy to supply the air separation unit. On the premise of stable operation of the system, the energy efficiency is higher. And because the system generates its own heat source and cold source, there is no need to introduce additional heat source and cold source supply, thus simplifying the equipment structure, improving the system efficiency, and reducing power consumption and costs.

[0049] Example 2

[0050] As a further improvement based on the above Example 1, in order to further improve the working energy efficiency of the system and the utilization rate of resources, a structure for further separating the liquid phase separated by the air pretreatment component is added after the gas-liquid separator 4. This structure can separate carbon dioxide from the liquid phase, so as to use carbon dioxide as a supplement to the circulating working medium or store it for further utilization.

[0051] Specifically, a carbon dioxide supply component and a carbon dioxide storage component are added after the gas-liquid separator 4 to complete the further utilization of resources.

[0052] Specifically, the structure of the carbon dioxide supply component includes a dryer 5, a second control valve 31, a first expansion valve 6 and a first evaporator 7. The dryer 5, the second control valve 31, the first expansion valve 6 and the first evaporator 7 are connected in sequence. The dryer 5 is connected to the liquid phase outlet of the gas-liquid separator 4. The dryer 5 is used to absorb water. The first evaporator 7 is connected to the gaseous carbon dioxide storage tank 14. The first expansion valve 6 is used to expand the liquid carbon dioxide to normal pressure. The first evaporator 7 is used to convert the normal pressure liquid carbon dioxide into gas and send it into the gaseous carbon dioxide storage tank 14. Among them, the heat source is connected to the heating inlet of the first evaporator 7 through a pipeline, and the heating outlet of the first evaporator 7 is vented.

[0053] When in use, when it is necessary to supply carbon dioxide to the gaseous carbon dioxide storage tank 14, open the second control valve 31. The liquid phase flowing out of the gas-liquid separator 4 is processed by the dryer 5, water is evaporated, and the remaining liquid carbon dioxide enters the first expansion valve 6 and expands to normal pressure. The carbon dioxide restored to normal pressure enters the first evaporator 7 and is converted into gas. The carbon dioxide at normal temperature and pressure converted into gas enters the gaseous carbon dioxide storage tank 14, thus completing the supplement of the gaseous carbon dioxide working medium.

[0054] When the working medium does not need to be supplemented, the carbon dioxide storage component can be used to store carbon dioxide. The carbon dioxide storage component includes a third control valve 32, a second booster pump 12 and a carbon dioxide storage tank 13. The second booster pump 12 is used to boost the pressure of the liquid carbon dioxide. The third control valve 32, the second booster pump 12 and the carbon dioxide storage tank 13 are connected in sequence. The third control valve 32 is connected to the outlet of the dryer 5. Open the third control valve 32, then the liquid carbon dioxide is boosted by the second booster pump 12 and stored in the carbon dioxide storage tank 13, and it can be applied in other occasions.

[0055] Example 3

[0056] As a further improvement based on the above-mentioned Embodiment 2, in order to further improve the working energy efficiency of the system and the utilization rate of resources, the structures of the energy release unit and the energy storage unit are further improved, and the formed system structure diagram is as Figure 7 shown.

[0057] Specifically, as Figure 4 shown, the energy storage unit further includes a third compressor 18 and a second heat exchanger 19. The first heat exchanger 17, the third compressor 18, the second heat exchanger 19, and the condenser 20 are connected in sequence. The second heat exchanger 19 is respectively connected to the cold storage tank 28 and the heat storage tank 29. As Figure 6 shown, the energy release unit further includes a third heat exchanger 23 and a first turbine 24. The second evaporator 22, the third heat exchanger 23, the first turbine 24, and the fourth heat exchanger 25 are connected in sequence. The third heat exchanger 23 is respectively connected to the cold storage tank 28 and the heat storage tank 29. Among them, the output shaft of the first turbine 24 is connected to the input shaft of the generator. The generator is used to generate electric energy, and the generator is electrically connected to the first compressor 2. The above improved system structure can achieve secondary heat exchange in both the energy storage unit and the energy release unit, and has a higher energy utilization rate for the system.

[0058] Specifically, in combination with Figure 7 , the system structure is described in detail as follows:

[0059] As Figure 1 and Figure 2 shown, the first control valve 30, the air purifier 1, the first compressor 2, the first cooler 3, the gas-liquid separator 4, and the second expansion valve 8 that are connected in sequence constitute an air pretreatment unit, which can perform temperature reduction and pressure regulation on the gas phase entering the separation tower 9.

[0060] The liquid phase separated by the gas-liquid separator 4 can be turned into normal-pressure gaseous carbon dioxide after secondary treatment through the dryer 5, the second control valve 31, the first expansion valve 6, and the first evaporator 7, and enter the gaseous carbon dioxide storage tank 14 for working medium replenishment. It can also pass through the third control valve 32, the second booster pump 12, and the carbon dioxide storage tank 13, so that the liquid carbon dioxide is pressurized by the second booster pump 12 and stored in the carbon dioxide storage tank 13, which is convenient for its application in other occasions.

[0061] In addition, during the working process of the air separation unit, derivative argon can also be separated from the air. An argon collection branch is connected to the separation tower 9. Specifically, the argon outlet of the separation tower 9, the first booster pump 10, and the argon storage tank 11 are connected in sequence.

[0062] Among them, as Figure 7 and Figure 4As shown in the figure, the energy storage unit includes a fifth control valve 34, a preheater 15, a second compressor 16, a first heat exchanger 17, a third compressor 18, a second heat exchanger 19, and a condenser 20 that are connected in sequence. The condenser 20 is connected to a liquid carbon dioxide storage tank 21. The fifth control valve 34 is connected to a gaseous carbon dioxide storage tank 14. A cold storage tank 28, a seventh control valve 36, the second heat exchanger 19, and a heat storage tank 29 are connected in sequence. The cold storage tank 28, the seventh control valve 36, the first heat exchanger 17, and the heat storage tank 29 are connected in sequence. The nitrogen outlet of the separation tower 9 / the oxygen outlet of the separation tower 9 is connected to the cooling inlet of the condenser 20, and the cooling outlet of the condenser 20 is vented.

[0063] Among them, as Figure 7 and Figure 6 shown, the energy release unit includes: a sixth control valve 35, a second evaporator 22, a third heat exchanger 23, a first turbine 24, a fourth heat exchanger 25, a second turbine 26, and a second cooler 27 that are connected in sequence. The second cooler 27 is connected to the gaseous carbon dioxide storage tank 14. The sixth control valve 35 is connected to the liquid carbon dioxide storage tank 21. The heat storage tank 29, an eighth control valve 37, the fourth heat exchanger 25, and the cold storage tank 28 are connected in sequence. The heat storage tank 29, the eighth control valve 37, the third heat exchanger 23, and the cold storage tank 28 are connected in sequence. The output shafts of the first turbine 24 and the second turbine 26 are respectively connected to the input shaft of a generator. The generator is used to generate electric energy, and the generator is electrically connected to the first compressor 2 to supply the electric energy generated by the generator for the first compressor 2 to use. The waste nitrogen outlet of the separation tower 9 is connected to the heating inlet of the second evaporator 22, and the heating outlet of the second evaporator 22 is vented. The nitrogen outlet of the separation tower 9 / the oxygen outlet of the separation tower 9 is connected to the cooling inlet of the second cooler 27, and the cooling outlet of the second cooler 27 is vented.

[0064] A compressed carbon dioxide energy storage method, based on the above compressed carbon dioxide energy storage system combined with air separation technology, includes the following steps:

[0065] Use the air separation unit to separate air to produce nitrogen, oxygen, carbon dioxide, and waste nitrogen. Use carbon dioxide as the working medium of the energy storage unit, use waste nitrogen as the heat source of the air separation unit, the energy storage unit, and the energy release unit respectively, and use nitrogen / oxygen as the cold source of the air separation unit, the energy storage unit, and the energy release unit respectively. During the low electricity consumption period, the energy storage unit compresses carbon dioxide and collects the heat energy and pressure energy generated during the process of compressing carbon dioxide. During the high electricity consumption period, the energy release unit converts the heat energy and pressure energy collected by the energy storage into electric energy and supplies it to the air separation unit and electrical equipment.

[0066] Specifically, combining the specific scheme of the embodiment of the present invention and Figure 7 , the implementation method includes the following steps:

[0067] In the initial state, the first control valve 30, the second control valve 31, the third control valve 32, the fourth control valve 33, the fifth control valve 34, the sixth control valve 35, the seventh control valve 36 and the eighth control valve 37 are closed, a total of eight control valves.

[0068] When the air separation unit starts to work, the second control valve 31, the fifth control valve 34, the sixth control valve 35, the seventh control valve 36 and the eighth control valve 37 are closed, and the first control valve 30, the third control valve 32 and the fourth control valve 33 are opened. The air separation unit of the compressed carbon dioxide energy storage system combined with the air separation technology starts to work.

[0069] Air at normal temperature and pressure enters the air purifier 1 for preliminary filtration to remove impurities contained in the air. The purified air enters the first compressor 2 for pressurization. The pressurized and heated air enters the first cooler 3 for cooling. During this cooling process, water vapor and carbon dioxide in the air will condense into liquid. The air in the gas-liquid mixed state then enters the gas-liquid separator 4 to separate the condensed water and carbon dioxide from the gaseous air. The gaseous air enters the second expansion valve 8 for expansion and cooling. The further cooled air enters the separation tower 9. In the separation tower 9, the components in the air are separated according to their different volatilities, separating nitrogen, argon, oxygen, waste nitrogen and carbon dioxide. Among them, the temperature of nitrogen is -196°±10°, argon is -186°±10°, oxygen is -183°±10°, waste nitrogen is 120°±10°, and carbon dioxide is -78°±10°. Since the temperatures of nitrogen and oxygen are relatively low, the separated nitrogen or oxygen enters the first cooler 3, the condenser 20 and the second cooler 27 respectively as a cold source to provide cooling and then is directly discharged into the atmosphere. The separated waste nitrogen, due to its high temperature, can enter the first evaporator 7, the preheater 15 and the second evaporator 22 respectively as a heat source to provide heat and then is directly discharged into the atmosphere. The separated argon is pressurized by the first booster pump 10 and stored in the argon storage tank 11. The condensed liquid part enters the dryer 5 to absorb moisture, and the liquid carbon dioxide is pressurized by the second booster pump 12 and stored in the carbon dioxide storage tank 13.

[0070] When the user is in the low electricity consumption period, the first control valve 30, the second control valve 31, the third control valve 32, the fourth control valve 33, the sixth control valve 35 and the eighth control valve 37 are closed, and the fifth control valve 34 and the seventh control valve 36 are opened. The energy storage unit of the compressed carbon dioxide energy storage system combined with the air separation technology starts to work.

[0071] The carbon dioxide at normal temperature and pressure stored in the gaseous carbon dioxide storage tank 14 enters the preheater 15 for preliminary preheating. After the carbon dioxide is heated up, it enters the second compressor 16 and is compressed using the electric energy during the low-demand period. After the carbon dioxide is heated up and pressurized, it enters the first heat exchanger 17 for heat exchange and cooling, transferring the heat to the heat storage medium from the cold storage tank 28. The heated-up heat storage medium is stored in the heat storage tank 29. The cooled carbon dioxide enters the third compressor 18 and is further compressed using the electric energy during the low-demand period. The high-pressure carbon dioxide after being heated up and pressurized enters the second heat exchanger 19 for heat exchange and cooling, transferring the heat to the heat storage medium from the cold storage tank 28. The heated-up heat storage medium is stored in the heat storage tank 29. The cooled high-pressure carbon dioxide enters the condenser 20 to absorb the cold energy of the oxygen generated by the separation tower 9 and is condensed into a liquid state. Finally, it enters the liquid carbon dioxide storage tank 21 for storage, completing the energy storage process.

[0072] When the user is at the peak electricity consumption period, the first control valve 30, the second control valve 31, the third control valve 32, the fourth control valve 33, the fifth control valve 34, and the seventh control valve 36 are closed, and the sixth control valve 35 and the eighth control valve 37 are opened. The energy release unit of the compressed carbon dioxide energy storage system combined with the air separation technology starts to operate.

[0073] The liquid carbon dioxide stored in the liquid carbon dioxide storage tank 21 enters the second evaporator 22 to absorb heat and is converted into gaseous carbon dioxide. The converted gaseous carbon dioxide enters the third heat exchanger 23 to absorb the heat from the heat storage medium in the heat storage tank 29 and is heated up. The heated-up carbon dioxide enters the first turbine 24 to expand and generate electricity. The carbon dioxide cooled after expansion enters the fourth heat exchanger 25 to absorb the heat from the heat storage medium in the heat storage tank 29 and is heated up. The heated-up carbon dioxide enters the second turbine 26 to output mechanical rotation to the generator to generate electricity. The carbon dioxide cooled after expansion and cooling enters the second cooler 27 to be cooled down. Finally, the carbon dioxide restored to the initial state is stored in the gaseous carbon dioxide storage tank 14, completing the energy release process.

[0074] Preferably, the carbon dioxide generated by the air separation unit of the system of the present invention can be input into the energy storage unit as the working medium. When it is necessary to supplement the storage amount of the working fluid in the energy storage unit, the third control valve 32, the fifth control valve 34, the sixth control valve 35, the seventh control valve 36, and the eighth control valve 37 are closed, and the first control valve 30, the second control valve 31, and the fourth control valve 33 are opened. The air separation unit of the compressed carbon dioxide energy storage system combined with the air separation technology starts to operate. The liquid carbon dioxide in the dryer 5 enters the first expansion valve 6 and expands to normal pressure. The carbon dioxide restored to normal pressure enters the first evaporator 7 and is converted into a gaseous state. The gaseous carbon dioxide at normal temperature and pressure enters the gaseous carbon dioxide storage tank 14. Thus, the supplement of the working fluid in the energy storage unit is completed.

[0075] Preferably, the nitrogen product, argon product, oxygen product, and carbon dioxide product generated in the present invention can be provided to different users as needed.

[0076] Preferably, the air separation unit and the energy release unit in the present invention can work simultaneously, and the electric energy generated by the energy release unit can be provided to the first compressor 2 of the air separation unit.

[0077] In summary, the present invention provides a compressed carbon dioxide energy storage system combined with air separation technology, which can effectively utilize the heat of waste nitrogen, various components generated by air separation, and low-valley electric energy, can realize the storage and release of energy, reduce the electricity cost of users, can produce air component products to supply the required users, and form a circular utilization of internal resources of the system. The specific advantages include:

[0078] 1. The system of the present invention has three different working units, namely, an energy storage mode, an energy release mode, and an air separation mode. The three units can work independently to complete the storage of energy, the release of energy, and the separation of air respectively. The energy release unit and the air separation unit can also be combined, and the electric energy generated in the energy release stage can be used for the air separation unit to realize the circular utilization of internal resources of the system.

[0079] 2. The present invention can use the waste nitrogen generated during air separation as a heat source to provide heat for the compressed carbon dioxide energy storage system, and can use the low-temperature components generated by air separation as a cold source to provide cold for the compressed carbon dioxide energy storage system. While ensuring the normal operation of the system, more energy can be stored for the energy conversion of the system, effectively improving the energy utilization rate of the system.

[0080] 3. The present invention can generate different components such as nitrogen, argon, oxygen, carbon dioxide, and waste nitrogen through the air separation unit. In addition to supplying different components to the required users as needed, carbon dioxide can also be supplied to the system as a working medium supplement source, or carbon dioxide can be captured and stored, which helps to mitigate the impact of climate change.

[0081] 4. The combination of the energy storage system and air separation technology realized by the present invention, due to the simple structure of the system and the relatively low overall pressure level, makes the energy storage system no longer dependent on a specific geographical environment and can be applied in a wide geographical area.

[0082] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments.

[0083] In addition, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention are within the scope protected by the present invention.

Claims

1. A compressed carbon dioxide energy storage system combined with air separation technology, characterized in that: include: A gaseous carbon dioxide storage tank (14), a liquid carbon dioxide storage tank (21), an energy storage unit, an energy release unit and an air separation unit, wherein the energy storage unit and the energy release unit are respectively arranged between the gaseous carbon dioxide storage tank (14) and the liquid carbon dioxide storage tank (21), the energy storage unit comprises a preheater (15), a second compressor (16) and a condenser (20) which are connected in sequence, the second compressor (16) is used to compress carbon dioxide, and the condenser (20) is used to condense carbon dioxide; the energy release unit comprises a second evaporator (22), a second turbine (26) and a second cooler (27) which are connected in sequence, the output shaft of the second turbine (26) is connected to the input shaft of a generator, the generator is used to generate electrical energy, and the second cooler (27) is used to cool the carbon dioxide entering the gaseous carbon dioxide storage tank (14); The air separation unit comprises an air pretreatment component and a separation tower (9), wherein the separation tower (9) is connected to the output end of the air pretreatment component, and the separation tower (9) is used to separate air to produce nitrogen, oxygen and contaminated nitrogen, wherein the nitrogen and oxygen are cold sources, and the contaminated nitrogen is a heat source; The cold source is supplied to the condenser (20), the second cooler (27) and the air pre-treatment component through pipelines, the heat source is supplied to the preheater (15) and the second evaporator (22) through pipelines, and the electric energy generated by the generator is supplied to the air pre-treatment component; The air pretreatment component comprises a first compressor (2), a first cooler (3), a gas-liquid separator (4) and a second expansion valve (8); the first compressor (2), the first cooler (3) and the gas-liquid separator (4) are connected; the gas phase outlet of the gas-liquid separator (4) is connected to the second expansion valve (8); the input end of the separation tower (9) is connected to the second expansion valve (8); the first compressor (2) is used to pressurize and heat the air; the first cooler (3) is used to cool the air; the gas-liquid separator (4) is used to separate liquid water and carbon dioxide from gaseous air; and the second expansion valve (8) expands and cools the gaseous air; The cold source is connected to the cooling inlet of the first cooler (3) through a pipeline, the cooling outlet of the first cooler (3) is vented, and the generator is electrically connected to the first compressor (2).

2. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 1 is characterized in that: The air pretreatment component further comprises an air purifier (1) and a first control valve (30); the air purifier (1) is arranged at the air inlet of the first compressor (2); the air purifier (1) is used to filter and remove impurities in the air; the first control valve (30) is arranged at the air inlet of the air purifier (1); the first control valve (30) is used to control the on and off of air.

3. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 2 is characterized in that: It also includes a carbon dioxide supply assembly, the carbon dioxide supply assembly including a dryer (5), a second control valve (31), a first expansion valve (6) and a first evaporator (7) which are connected in sequence, the dryer (5) being connected to the liquid phase outlet of the gas-liquid separator (4), and the first evaporator (7) being connected to the gaseous carbon dioxide storage tank (14); The heat source is connected to the heating inlet of the first evaporator (7) through a pipeline, and the heating outlet of the first evaporator (7) is vented.

4. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 3 is characterized in that: The device also comprises a carbon dioxide storage component, the carbon dioxide storage component comprising a third control valve (32), a second booster pump (12) and a carbon dioxide storage tank (13) which are connected in sequence, the second booster pump (12) being used to pressurize the liquid carbon dioxide, and the third control valve (32) being connected to the outlet of the dryer (5).

5. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 3 is characterized in that: The invention also comprises a heat exchange unit, the heat exchange unit comprising a cold storage tank (28), a first heat exchanger (17), a fourth heat exchanger (25) and a heat storage tank (29), the first heat exchanger (17) being arranged between the second compressor (16) and the condenser (20), the fourth heat exchanger (25) being arranged between the second evaporator (22) and the second turbine (26), a heat storage medium being arranged in the cold storage tank (28) and the heat storage tank (29), the cold storage tank (28) and the heat storage tank (29) forming a heat exchange circuit between the first heat exchanger (17) and the fourth heat exchanger (25), and the heat storage medium being able to flow in the heat exchange circuit.

6. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 5 is characterized in that: The energy storage unit further comprises a third compressor (18) and a second heat exchanger (19); the first heat exchanger (17), the third compressor (18), the second heat exchanger (19), and the condenser (20) are connected in sequence; and the second heat exchanger (19) is respectively connected to a cold storage tank (28) and a heat storage tank (29).

7. The compressed carbon dioxide energy storage system combined with air separation technology according to claim 6 is characterized in that: The energy release unit further comprises a third heat exchanger (23) and a first turbine (24); the second evaporator (22), the third heat exchanger (23), the first turbine (24) and the fourth heat exchanger (25) are connected in sequence; the third heat exchanger (23) is connected to the cold storage tank (28) and the heat storage tank (29) respectively; The output shaft of the first turbine (24) is connected to the input shaft of a generator, the generator is used to generate electrical energy, and the generator is electrically connected to the first compressor (2).

8. A compressed carbon dioxide energy storage method, characterized in that: The method is applied to the compressed carbon dioxide energy storage system combined with air separation technology as described in claim 7, comprising the following steps: Using an air separation unit to separate air to produce nitrogen, oxygen, carbon dioxide and polluted nitrogen, using the polluted nitrogen as a heat source for the air separation unit, the energy storage unit and the energy release unit, respectively, using nitrogen as a cooling source for the air separation unit, the energy storage unit and the energy release unit, respectively, or using oxygen as a cooling source for the air separation unit, the energy storage unit and the energy release unit, respectively; During low electricity consumption, the energy storage unit compresses CO2 and collects the heat and pressure energy generated during the compression process. During peak electricity consumption, the energy release unit converts the thermal energy and pressure energy collected by the energy storage into electrical energy, and supplies it to the air separation unit and electrical equipment.

Images