An environmentally adaptive step-down energy storage system and its working method

Abstract

The present invention provides an environmentally adaptive step-down energy storage system, comprising an air storage tank, a liquid storage tank, and a cold and heat storage unit. The air outlet of the air storage tank is connected to the liquid storage tank via a first pipeline. A compressor unit and a second heat exchanger are sequentially provided on the first pipeline. The compressor unit includes a compressor and a first heat exchanger. The second heat exchanger is used to convert the medium in the pipe from gas to liquid. The output end of the liquid storage tank is connected to the air storage tank via a second pipeline. A pressure-stabilizing and pressure-reducing valve, a third heat exchanger, and an expansion generator unit are sequentially provided on the second pipeline. The expansion generator unit includes an expansion generator and a fourth heat exchanger. The cold and heat storage unit is arranged between the first and second heat exchangers and can achieve internal heat exchange. The third heat exchanger is connected to the cold supply end and can provide cold energy. The environmentally adaptive step-down energy storage system of the present invention has a compact structure, low manufacturing and use costs, can be self-adjusted according to different usage requirements, is flexible to use, can adapt to extreme environments, and has a wide range of applications.

Description

Technical Field

[0001] The present invention relates to an energy storage system, and in particular to an environment-adaptive step-down energy storage system and a working method thereof. Background Art

[0002] Compressed air energy storage technology is a physical energy storage technology that uses compressed air to store energy. It has the advantages of large energy storage capacity, high safety, economy, environmental protection and mature technology. It plays an important role in future energy systems, especially in promoting the use of renewable energy and improving grid stability.

[0003] Carbon dioxide energy storage (CES) technology is a new physical energy storage technology based on compressed air energy storage (CAES) and the Brayton power generation cycle. As a new technology, CO2 energy storage, in existing technical applications, uses a multi-stage compressor to convert atmospheric pressure gaseous CO2 into high-pressure liquid CO2 during low electricity prices, converting electrical energy into the form of CO2 internal energy for storage; during peak electricity consumption, a multi-stage expander is used to expand the high-pressure liquid CO2 into atmospheric pressure gaseous CO2 for power generation, ultimately achieving the storage and release of electrical energy. However, this system has the following disadvantages:

[0004] 1. The investment is substantial. The entire system includes a low-pressure gas storage tank, a high-pressure storage tank, a compressor unit, a turbine unit, a heat exchange system, and a large number of cold and heat storage tanks. The investment in the cold and heat storage tanks, as well as the heat exchangers, is particularly substantial, and the cost of promoting the technology cannot be ignored.

[0005] 2. The system has great limitations. The relevant parameters of the entire system are set in the early stage, and it cannot be adaptively adjusted in the later stage. It cannot be effectively adjusted for different usage scenarios and external environments, and has great limitations.

[0006] 3. All energy sources rely on electricity conversion, and operating costs remain high. Summary of the Invention

[0007] Technical problems to be solved

[0008] The technical problem to be solved by the present invention is to provide an environmentally adaptive step-down energy storage system and its working method which has a compact structure, low equipment cost and use cost, can meet different usage requirements, and can adapt to extreme weather and regions.

[0009] Technical solutions to the problem

[0010] The present invention provides an environmentally adaptive step-down energy storage system, which includes an air storage tank 1, a liquid storage tank 6 and a cold and heat storage unit. The air outlet end of the air storage tank 1 is connected to the liquid storage tank 6 through a first pipeline. A compressor unit and a second heat exchanger 33 are sequentially provided on the first pipeline. The compressor unit includes a compressor and a first heat exchanger arranged at the rear end of the compressor. The second heat exchanger 33 is connected to an evaporative condenser 41 and is used to convert the medium in the pipe from gas to liquid; the output end of the liquid storage tank 6 is connected to the air storage tank 1 through a second pipeline. A pressure stabilizing and reducing valve 7, a third heat exchanger 34 and an expansion generator set are sequentially provided on the second pipeline. The expansion generator set includes an expansion generator and a fourth heat exchanger connected in series. The cold and heat storage unit is arranged between the first heat exchanger and the fourth heat exchanger and can realize internal heat exchange. The third heat exchanger 34 is connected to a cold supply end and can provide cold energy for it.

[0011] Furthermore, the output pressure of the pressure-stabilizing and pressure-reducing valve 7 is adjustable and can make the temperature corresponding to the energy-releasing pressure lower than the current ambient temperature, or reach the cooling temperature required for production and life.

[0012] Furthermore, the gasification temperature at the output end of the pressure stabilizing and reducing valve 7 is between -50°C and 30°C.

[0013] Furthermore, the compressor groups are multiple and are connected in series.

[0014] Furthermore, the compressor unit includes a first-stage compressor 21, a first heat exchanger I 31, a second-stage compressor 22 and a first heat exchanger II 32 connected in series.

[0015] Furthermore, the expansion generator set includes a plurality of fourth heat exchangers and an expansion generator arranged between two adjacent fourth heat exchangers.

[0016] Furthermore, the expansion generator set includes a fourth heat exchanger I 35 , a first-stage expansion generator 81 , a fourth heat exchanger II 36 , a second-stage expansion generator 82 and a fourth heat exchanger III 37 , which are arranged in sequence.

[0017] Furthermore, the cold and heat storage unit includes a heat storage tank 91 and a cold storage tank 92. The output end of the heat storage tank 91 is provided with a first circulation pump, and the output end of the first circulation pump branches into first branches with the same number as the fourth heat exchangers. The first branches are connected to the cold storage tank 92 after heat exchange through each of the fourth heat exchangers; the output end of the cold storage tank 92 is provided with a second circulation pump, and the output end of the second circulation pump branches into second branches with the same number as the first heat exchangers. The second branches are connected to the heat storage tank 91 after heat exchange through each of the first heat exchangers.

[0018] Furthermore, it also includes a phase-change cold and heat storage tank 42, which is arranged between the second heat exchanger 33 and the third heat exchanger 34, and is used to store the heat generated by the liquefaction of the medium in the second heat exchanger 33 in the phase-change cold and heat storage tank 42 and provide heat for the vaporization of the medium in the third heat exchanger 34 during extreme weather or in extreme weather areas, or store the cold energy generated by the vaporization of the medium in the third heat exchanger 34 in the phase-change cold and heat storage tank 42 and provide cold energy for the liquefaction of the medium in the second heat exchanger 33.

[0019] Furthermore, the second heat exchanger 33 is selectively connected to the evaporative condenser 41 or the phase-change cold and heat storage tank 42 , and the third heat exchanger 34 is selectively connected to the cold supply end or the phase-change cold and heat storage tank 42 .

[0020] Furthermore, when the cooling end is a domestic cooling end, the cooling energy provided by the third heat exchanger 34 is -10°C to 5°C; when the cooling end is an industrial cooling end, the cooling energy provided by the third heat exchanger is -45°C to -35°C.

[0021] Furthermore, when the cooling end is for domestic cooling, the pressure-stabilizing and pressure-reducing valve 7 adjusts the medium vaporization pressure to 2Mpa-3Mpa; when the cooling end is for industrial cooling, the pressure-stabilizing and pressure-reducing valve adjusts the medium vaporization pressure to 0.8Mpa-1.2Mpa.

[0022] Furthermore, a liquefaction buffer tank 5 is connected in series between the second heat exchanger 33 and the liquid storage tank 6 . The liquefaction buffer tank 5 is provided with a loop pipe 51 . The loop pipe 51 is connected to the input end of the second heat exchanger 33 to form a loop.

[0023] At the same time, the present invention also provides a working method of an environment-adaptive step-down energy storage system, which comprises the following steps:

[0024] S1. Energy storage:

[0025] S11. The normal temperature and pressure gaseous medium in the gas storage tank 1 is compressed in multiple stages by multiple compressors in the compressor unit to form a high temperature and high pressure gaseous medium. Simultaneously, the first heat exchanger in the compressor unit cools the medium in the first pipeline to form a medium temperature and high pressure gaseous medium.

[0026] S12: The second heat exchanger 33 at the rear end of the compressor unit cools down the medium-temperature and high-pressure gaseous medium in the first pipeline to form a liquid medium, which then passes through the liquefaction buffer tank 5 and enters the liquid storage tank for storage;

[0027] S13: The medium that is not completely liquefied after cooling returns to the second heat exchanger 33 through the loop pipe 51 to continue cooling until it is completely liquefied;

[0028] S2. Energy release:

[0029] S21: Power generation. Adjust the opening of the pressure-stabilizing and pressure-reducing valve 7 so that the temperature corresponding to the energy release pressure is lower than the current ambient temperature. The medium in the second pipeline is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The medium is then expanded by the expansion generator to generate electricity. Ultimately, the medium in the second pipeline is converted to a medium at normal temperature and pressure and stored in the gas storage tank 1.

[0030] S22: Cooling is taken. The opening of the pressure-stabilizing and pressure-reducing valve 7 is adjusted to ensure that the temperature corresponding to the energy release pressure reaches the temperature required for production or daily life. The third heat exchanger 34 provides the cooling energy to the cooling end for production or daily life. The high-pressure and low-temperature gaseous medium after cooling is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The gaseous medium is then expanded and generates electricity by the expansion generator, and finally forms a gaseous medium at normal temperature and pressure, which is stored in the gas storage bin.

[0031] Either step S21 or step S22 is performed.

[0032] Furthermore, during the energy storage and release process, the cold medium in the cold storage tank 92 exchanges heat with the first heat exchanger on the first pipeline through the first circulation pump, and cools the medium in the first pipeline. After the heat exchange, a hot medium is formed and stored in the heat storage tank 91; the hot medium in the heat storage tank 91 exchanges heat with the fourth heat exchanger on the second pipeline through the second circulation pump, and heats the medium in the second pipeline. After the heat exchange, a cold medium is formed and stored in the cold storage tank 92.

[0033] Furthermore, the medium in the gas storage tank 1 and the liquid storage tank 6 is carbon dioxide.

[0034] Furthermore, the second heat exchanger 33 is connected to an evaporative condenser 41 and can exchange heat with air to generate cooling.

[0035] Furthermore, energy is stored at night when electricity prices are low, and energy is released during the day when electricity prices are high.

[0036] Furthermore, in extreme weather, when the ambient temperature is lower than the temperature required for the expansion and vaporization of the medium, the second heat exchanger 33 is disconnected from the evaporative condenser 41 and connected to the phase-change cold and heat storage tank 42, and the heat generated by the second heat exchanger 33 for the liquefaction of the medium in the first pipeline is stored in the phase-change cold and heat storage tank 42, and heat is provided for the vaporization of the medium in the third heat exchanger 34.

[0037] Furthermore, the temperature of the medium in the liquid storage tank 6 is higher than the ambient nighttime temperature.

[0038] Furthermore, the compressor unit can compress the 0.1Mpa normal temperature gaseous medium in the gas storage tank 1 into a 7Mpa-8Mpa 35℃-45℃ gaseous medium, and cool the medium through the second heat exchanger 33 to form an isobaric 25℃-35℃ liquid medium.

[0039] Beneficial effects

[0040] The environmentally adaptive step-down energy storage system of the present invention optimizes the traditional carbon dioxide energy storage form of single electricity-to-electricity conversion, abandons a large number of energy conversion methods in the form of cold and heat storage, and replaces them with a lightweight equipment and energy storage mode that can adaptively adjust the energy release pressure according to the ambient temperature. It can also flexibly convert the energy extraction mode according to production needs, thereby realizing a high-quality, low-cost, more flexible and changeable new energy storage mode, and improving the economic competitiveness and industrial adaptability of carbon dioxide energy storage. At the same time, the present invention only retains a single small cold storage tank and heat storage tank, realizes the exchange of heat energy generated by compression and cold energy generated by expansion, completes the energy offset between sensible heat, and eliminates a large number of sensible heat storage tanks for liquefaction and vaporization. In the liquefaction and condensation stage after compression is completed, the liquefaction temperature of up to 31°C and the low temperature during compression and energy storage at night with low electricity prices are effectively utilized to realize the liquefaction and condensation process of carbon dioxide gas through simple and low-cost evaporative cooling. In the energy release stage, in the gasification process after the pressure-stabilizing and pressure-reducing valve, the energy release pressure is manually adjusted according to the ambient temperature so that the evaporation temperature corresponding to the energy release pressure is lower than the ambient temperature, thereby realizing that the heat energy required for the gasification process all comes from the air. Gasification can be achieved through a single evaporative cooling, thereby eliminating a large number of cold storage tanks and heat storage tanks, and the absorbed cold energy and heat energy all come from the air, thereby greatly reducing the initial equipment cost and the later operating cost. Due to the different physical properties of the cold energy temperatures generated by the gasification of carbon dioxide at different pressures, energy conversion can be performed according to production needs. Cold energy and electricity can be provided for cooling places and electricity demand places with different temperature requirements in the range of -50°C to 30°C, making the system operation more flexible and more adaptable. For extreme climate areas, phase change cold and heat storage tanks are added to store the heat generated by liquefaction in the phase change cold and heat storage tanks to meet the heat requirements for carbon dioxide gasification, reducing regional limitations. The environmentally adaptive step-down energy storage system of the present invention has a compact structure, low manufacturing cost and use cost, can be self-adjusted according to different use requirements, is flexible to use, and can adapt to extreme environments, with a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a connection diagram of the environment-adaptive step-down energy storage system of the present invention;

[0042] In the figure: 1. Air storage tank, 21. First-stage compressor, 22. Second-stage compressor, 31. First heat exchanger I, 32. First heat exchanger II, 33. Second heat exchanger, 34. Third heat exchanger, 35. Fourth heat exchanger I, 36. Fourth heat exchanger II, 37. Fourth heat exchanger III, 41. Evaporative condenser, 42. Phase-change cold and heat storage tank, 5. Liquefaction buffer tank, 51. Loop pipe, 6. Liquid storage tank, 7. Pressure stabilizing and reducing valve, 81. First-stage expansion generator, 82. Second-stage expansion generator, 91. Heat storage tank, 92. Cold storage tank 92. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0044] See Figure 1 The present invention provides an environmentally adaptive step-down energy storage system, which includes a gas storage tank 1, a liquid storage tank 6 and a cold and heat storage unit. The gas storage tank 1 is used to store a gaseous medium, and the liquid storage tank 6 is used to store a liquid medium. In this embodiment, the above-mentioned medium is carbon dioxide; the gas outlet end of the gas storage tank 1 is connected to the liquid storage tank 6 through a first pipeline. A compressor unit and a second heat exchanger 33 are sequentially provided on the first pipeline along the medium conveying direction. The compressor unit includes a compressor and a first heat exchanger arranged at the rear end of the compressor. The compressor unit is a plurality of units and is connected in series to achieve multi-stage compression. The compressor is used to compress the gaseous medium and increase the medium pressure. At the same time, heat is generated during the compression process. The first heat exchanger is used to eliminate the generated heat; the second heat exchanger 33 is connected to a condenser (cooler) to convert the medium in the pipe (carbon dioxide) from gas to liquid and store it in liquid form in the liquid storage tank 6. In this embodiment, the condenser is an evaporative condenser 41, or called an evaporative cooler, which can exchange heat with air. The above-mentioned first pipeline serves as an energy storage pipeline.

[0045] The output end of the liquid storage tank 6 is connected to the gas storage tank 1 through the second pipeline. The second pipeline is provided with a pressure stabilizing and reducing valve 7, a third heat exchanger 34 and an expansion generator set in sequence along the medium conveying direction. The expansion generator set includes an expansion generator and a fourth heat exchanger connected in series. The expansion generator and the fourth heat exchanger are both multiple and can realize multiple expansion power generation. During the expansion power generation process, the pressure and temperature of the medium will decrease. Heat exchange is performed through the fourth heat exchanger to heat the medium, thereby increasing the power generation. The cold and heat storage unit is arranged on the first heat exchanger. Internal heat exchange can be achieved between the first heat exchanger and the fourth heat exchanger, and the third heat exchanger 34 is connected to a cold supply end and can provide cold energy for it. The cold supply end can be a domestic cold supply end or an industrial cold supply end. The temperature of the industrial cold supply end is lower than the temperature of the domestic cold supply end. In this embodiment, when the cold supply end is a domestic cold supply end, the cold energy provided by the third heat exchanger 34 is -10°C to 5°C; when the cold supply end is an industrial cold supply end, the cold energy provided by the third heat exchanger 34 is -45°C to -35°C. The above-mentioned second pipeline serves as an energy release pipeline.

[0046] In the present application, the output pressure of the pressure-stabilizing and pressure-reducing valve 7 is adjustable, that is, by adjusting the opening of the pressure-stabilizing and pressure-reducing valve 7, the energy release pressure can be adjusted, which can make the temperature corresponding to the energy release pressure lower than the current ambient temperature, or reach the cooling temperature required for production and life, thereby meeting different usage requirements, including main power generation or main cooling, that is, an operating mode biased towards power generation or cooling.

[0047] At the same time, in order to adapt to different usage environments, especially in extreme weather areas, the present application also includes a phase change cold and heat storage tank 42, in which a phase change material is provided. The phase change material absorbs or releases a large amount of latent heat during the phase change process, thereby generating a cold or heat storage function. Its energy density is high, and the heat storage density of the phase change heat storage is 5 to 10 times that of the sensible heat storage. times or even higher; the phase-change cold and heat storage tank 42 is arranged between the second heat exchanger 33 and the third heat exchanger 34, and is used to store the heat generated by the liquefaction of the medium in the second heat exchanger 33 in the phase-change cold and heat storage tank 42 during extreme weather (time) or in extreme weather areas (places), and provide heat for the vaporization of the medium in the third heat exchanger 34, or store the cold energy generated by the vaporization of the medium in the third heat exchanger 34 in the phase-change cold and heat storage tank 42, and provide cold energy for the liquefaction of the medium in the second heat exchanger 33; therefore, the phase-change cold and heat storage tank 42 and the evaporative condenser 41 are simultaneously connected to the second heat exchanger 33 in parallel, while the cold supply (take-off) end and the phase-change cold and heat storage tank 42 (the other end) are simultaneously connected to the third heat exchanger 34 in parallel. According to different operating conditions, the second heat exchanger 33 is selectively connected to the evaporative condenser 41 or the phase-change cold and heat storage tank 42, and the third heat exchanger 34 is selectively connected to the cold supply end or the phase-change cold and heat storage tank 42.

[0048] The cold and heat storage unit includes a heat storage tank 91 and a cold storage tank 92. The output end of the heat storage tank 91 is provided with a first circulation pump, and the output end of the first circulation pump branches into a first branch. The number of the first branches is the same as the number of the fourth heat exchangers, and they correspond one to one. The first branches are connected to the cold storage tank 92 after heat exchange through each fourth heat exchanger; the output end of the cold storage tank 92 is provided with a second circulation pump, and the output end of the second circulation pump branches into a second branch. The number of the second branches is the same as the number of the first heat exchangers, and they correspond one to one. The second branches are connected to the heat storage tank 91 after heat exchange through each first heat exchanger.

[0049] A liquefaction buffer tank 5 is connected in series between the second heat exchanger 33 and the liquid storage tank 6. A loop pipe 51 is provided on the liquefaction buffer tank 5. The loop pipe 51 is connected to the input end of the second heat exchanger 33 to form a loop for transporting the unliquefied medium back to the second heat exchanger 33 for further cooling and liquefaction.

[0050] The following is a detailed description of the energy storage system for this application:

[0051] The entire system includes an air storage tank 1, a liquid storage tank 6, a heat storage tank 91 and a cold storage tank 92. The air storage tank 1 is used to store gaseous carbon dioxide (medium), and the liquid storage tank 6 is used to store liquid carbon dioxide (medium). The output end of the air storage tank 1 is connected to the liquid storage tank 6 through a first pipeline. On the first pipeline, a first-stage compressor 21, a first heat exchanger I 31, a second-stage compressor 22, a first heat exchanger II 32, a second heat exchanger 33 and a liquefaction buffer tank 5 are sequentially arranged (in series) along the medium conveying direction. The second heat exchanger 33 is used to liquefy the medium in the first pipeline. The temperature of the medium is reduced, so that the medium is converted from gaseous to liquid, and is stored in the liquid storage tank 6. The second heat exchanger 33 is connected to the evaporative condenser 41 and the phase-change cold and heat storage tank 42 at the same time, that is, the evaporative condenser 41 and the phase-change cold and heat storage tank 42 are in parallel, and can be connected to the evaporative condenser 41 or the phase-change cold and heat storage tank 42 according to different ambient temperatures; a loop pipe 51 is provided on the liquefaction buffer tank 5, and the loop pipe 51 is connected to the input end of the second heat exchanger 33 to form a loop, so that the medium that has not been completely converted into liquid re-enters the second heat exchanger The device 33 is cooled and cooled to fully convert it into liquid. The first pipeline is used as an energy storage pipeline; the output end of the liquid storage tank 6 is connected to the gas storage tank 1 through a second pipeline. On the second pipeline, a pressure stabilizing and reducing valve 7, a third heat exchanger 34, a fourth heat exchanger I 35, a first-level expansion generator 81, a fourth heat exchanger II 36, a second-level expansion generator 82 and a fourth heat exchanger III 37 are sequentially arranged along the medium delivery direction. The third heat exchanger 34 is connected to the cold end and the phase change cold and heat storage tank 42 at the same time, that is, the cold end and the phase change cold and heat storage tank 42 are in parallel. The state of connection can select one of the cold end or the phase change cold and heat storage tank 42 according to different usage requirements. At the same time, the opening of the pressure stabilizing and pressure reducing valve 7 is adjustable, thereby forming different energy release (expansion) pressures. Different energy release pressures form different vaporization temperatures. For example, when it is necessary to provide a temperature of -35°C for the freeze-drying equipment, the vaporization pressure can be adjusted to about 1Mpa, and its vaporization temperature at 1Mpa is about -40°C. Or when it is necessary to provide a temperature of -8°C for the residential community air conditioner, the vaporization pressure can be adjusted to about 2.5Mpa, and its vaporization temperature at 2.The vaporization temperature of 5Mpa is about -12℃, and the required temperature is adjusted by the pressure-stabilizing and pressure-reducing valve 7. By adjusting its opening, it can meet the use requirements of any temperature from -50℃ to 30℃, and provide cold energy of corresponding temperature for the cold end; the expansion generator is a turbine expansion generator, which can expand and generate electricity through the medium in the second pipeline. The fourth heat exchanger is used to heat and heat the medium in the second pipeline, thereby increasing the power generation. The fourth heat exchanger at the end is used to increase the temperature in the pipe to reach room temperature, which can then be stored in the gas storage bin 1; at the same time, the first circulation pump at the output end of the heat storage tank 91 branches into three first branches, and the three first branches are respectively connected to The fourth heat exchanger I 35, the fourth heat exchanger II 36, and the fourth heat exchanger III 37 are connected to perform heat exchange, which increases the temperature of the medium in the second pipeline and improves power generation. Simultaneously, after heat exchange, the temperature of the medium in the first branch decreases, forming a low-temperature medium, which is then transported to the cold storage tank 92. The second circulating pump at the output end of the cold storage tank 92 branches into two second branches, which are respectively connected to the first heat exchanger I 31 and the first heat exchanger II 32 to cool the medium in the first pipeline, pre-cooling it for the next liquefaction step. Simultaneously, after heat exchange, the temperature of the medium in the second branch increases, forming a high-temperature medium, which is then transported to the heat storage tank 91.

[0052] When the environmentally adaptive step-down energy storage system of this application is working, it mainly includes energy storage and energy release.

[0053] The following is a brief description:

[0054] Energy storage process: When electricity prices are low at night, normal temperature and normal pressure gaseous carbon dioxide is compressed by a multi-stage compressor to generate 7.3 MPa high-temperature gaseous carbon dioxide. At the same time, the heat energy is stored in the heat storage tank 91 through the first heat exchanger I 31 and the first heat exchanger II 32, and the carbon dioxide gas is cooled simultaneously; the 7.3 MPa medium-temperature and high-pressure gaseous carbon dioxide is exchanged with the ambient temperature below 31°C at night through the second heat exchanger 33 and the evaporative condenser 41. The high-power liquefaction latent heat comes entirely from the air, realizing the liquefaction process of air cooling. Finally, the 7.3 MPa 31°C liquid carbon dioxide is stored in the liquid storage tank 6, and the energy storage process is finally completed; when in extreme weather areas, the evaporative condenser 41 is closed, and the heat generated by liquefaction is stored in the phase change cold and heat storage tank 42 through the second heat exchanger 33.

[0055] Energy release process: When electricity prices are high during the day, energy is released. The energy release process can be divided into two situations, namely energy release power generation mode and energy release cooling mode.

[0056] 1. Energy release and power generation: During the energy release process, the system can adaptively and manually adjust the energy release pressure according to the ambient temperature, so that the temperature corresponding to the energy release pressure is lower than the current ambient temperature, and finally the temperature is increased through the fourth heat exchanger I 35 and the fourth heat exchanger II 36. The heated high-temperature and high-pressure gaseous carbon dioxide is expanded to generate electricity through the generator, and finally converted into normal-pressure gaseous carbon dioxide and stored in the gas storage bin; the cold energy generated during the expansion process is stored in the cold storage tank 92, and is heated by heat exchange with the heat energy generated by compression; in extreme weather areas, the heat required for gasification is derived from the phase-change cold and heat storage tank 42, and the cold energy generated by gasification is stored in the phase-change cold and heat storage tank 42 through the third heat exchanger 34.

[0057] 2. Energy release and cold extraction: During the energy release process, the energy release pressure is adjusted according to the saturation state of carbon dioxide gasification and the temperature required for production and life, so that the temperature corresponding to the energy release pressure reaches the required production temperature. For example, when it is necessary to provide a temperature of -35°C for the freeze-drying equipment, the gasification pressure can be adjusted to about 1 MPa, and its gasification temperature at 1 MPa is about -40°C; or when it is necessary to provide a temperature of -8°C for the air conditioning in the residential community, the gasification pressure can be adjusted to about 2.5 MPa, and its gasification temperature at 2.5 MPa is about -12°C; finally, the cold energy is extracted through the third heat exchanger 34 for other production and life needs; the high-pressure and low-temperature gaseous carbon dioxide after the cold energy extraction is heated by the fourth heat exchanger I 35 and the fourth heat exchanger II 36, and the heated high-pressure and high-temperature gaseous carbon dioxide is expanded to generate electricity and finally converted into normal-pressure gaseous carbon dioxide and stored in the gas storage bin 1; the cold energy generated during the expansion process is also stored in the cold storage tank 92, and is heat-exchanged with the heat energy generated by compression to heat it up.

[0058] At the same time, the present invention also provides a working method of an environment-adaptive step-down energy storage system, which comprises the following steps:

[0059] S1. Energy storage:

[0060] S11: The normal temperature and pressure gaseous medium (carbon dioxide) in the gas storage tank 1 is compressed in multiple stages by multiple compressors in the compressor unit to form a high-temperature and high-pressure gaseous medium. Simultaneously, the first heat exchanger in the compressor unit cools the medium in the first pipeline to form a medium-temperature and high-pressure gaseous medium.

[0061] S12: The second heat exchanger 33 at the rear end of the compressor unit cools down the medium-temperature and high-pressure gaseous medium in the first pipeline to form a liquid medium, which then passes through the liquefaction buffer tank 5 and enters the liquid storage tank 6 for storage. The second heat exchanger 33 is connected to an evaporative condenser 41 and can exchange heat with the air to obtain cooling;

[0062] In this embodiment, the compressor unit can compress the 0.1 MPa normal temperature gaseous medium in the gas storage bin into a high temperature gaseous medium of 7 MPa-8 MPa. At the same time, the heat is dissipated through the first heat exchanger to form a gaseous medium of 35°C-45°C, that is, a medium temperature gaseous medium. Preferably, it is compressed into a 7.3 MPa 40°C gaseous medium, and the second heat exchanger 33 is used to cool the state medium and form an isobaric liquid medium of 25°C-35°C. The second heat exchanger 33 exchanges heat with the ambient temperature below 31°C at night through evaporative cooling. Preferably, the temperature is reduced to form a 7.3 MPa 31°C liquid medium.

[0063] During the energy storage process, the cold medium in the cold storage tank 92 exchanges heat with the first heat exchanger on the first pipeline through the first circulation pump, and cools the medium in the first pipeline. After the heat exchange, hot medium is formed and stored in the heat storage tank 91;

[0064] S13: The medium that has not been completely liquefied after being cooled returns to the second heat exchanger 33 through the loop pipe 51 to continue cooling until it is completely liquefied.

[0065] The above energy storage process is carried out at night when electricity prices are low;

[0066] S2. Energy release:

[0067] S21, power generation mode: adjust the opening of the pressure-stabilizing and pressure-reducing valve 7 so that the temperature corresponding to the energy release pressure is lower than the current ambient temperature. The medium in the second pipeline is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The medium is then expanded by the expansion generator to generate electricity. Ultimately, the medium in the second pipeline is converted to a medium at normal temperature and pressure and stored in the gas storage tank 1.

[0068] S22, cooling mode: adjust the opening of the pressure-stabilizing and pressure-reducing valve 7 so that the temperature corresponding to the energy release pressure reaches the temperature required for production or daily life. The third heat exchanger 34 provides this cooling energy to the cooling end for production or daily life. The high-pressure and low-temperature gaseous medium after cooling is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The medium is then expanded and generated electricity by the expansion generator, ultimately forming a normal-temperature and normal-pressure gaseous medium which is stored in the gas storage bin 1. The heat exchange and temperature increase by the fourth heat exchanger can increase the medium temperature, thereby increasing the power generation. At the same time, the fourth heat exchanger III 37 can bring the medium at the end of the second pipeline to normal temperature and store it in the gas storage bin 1.

[0069] During the energy release process, the hot medium in the heat storage tank 91 exchanges heat with the fourth heat exchanger on the second pipeline through the second circulation pump, and heats the medium in the second pipeline. After the heat exchange, the cold medium is formed and stored in the cold storage tank 92;

[0070] The above-mentioned high pressure, medium pressure and low pressure are relative pressures, and high temperature, medium temperature and low temperature are relative temperatures.

[0071] The above energy release process is carried out during the day when electricity prices are high, and the above step S21 (cooling mode) and step S22 (power generation mode) can be performed selectively or simultaneously, that is, cooling and power generation. Depending on whether the focus is on power generation or cooling, it is necessary to adjust the opening of the pressure-stabilizing and pressure-reducing valve 7 to obtain the appropriate energy release pressure and vaporization temperature.

[0072] When in extreme weather or in extreme weather areas, and the ambient temperature is lower than the temperature required for the expansion and vaporization of the medium, the second heat exchanger 33 is disconnected from the evaporative condenser 41 and connected to the phase-change cold and heat storage tank 42. The heat generated by the second heat exchanger 33 for liquefying the medium in the first pipeline is stored in the phase-change cold and heat storage tank 42, providing heat for the vaporization of the medium in the third heat exchanger 34 so that it can operate smoothly. During this process, the third heat exchanger 34 is disconnected from the cold supply end and connected to the phase-change cold and heat storage tank 42, and smooth vaporization is achieved through the cold energy in the phase-change cold and heat storage tank.

[0073] The environmentally adaptive step-down energy storage system of the present invention optimizes the traditional carbon dioxide energy storage form of single electricity-to-electricity conversion, abandons a large number of energy conversion methods in the form of cold and heat storage, and replaces them with a lightweight equipment and energy storage mode that can adaptively adjust the energy release pressure according to the ambient temperature. It can also flexibly convert the energy extraction mode according to production needs, thereby realizing a high-quality, low-cost, more flexible and changeable new energy storage mode, and improving the economic competitiveness and industrial adaptability of carbon dioxide energy storage. At the same time, the present invention only retains a single small cold storage tank and heat storage tank, realizes the exchange of heat energy generated by compression and cold energy generated by expansion, completes the energy offset between sensible heat, and eliminates a large number of sensible heat storage tanks for liquefaction and vaporization. In the liquefaction and condensation stage after compression is completed, the liquefaction temperature of up to 31°C and the low temperature during compression and energy storage at night with low electricity prices are effectively utilized to realize the liquefaction and condensation process of carbon dioxide gas through simple and low-cost evaporative cooling. In the energy release stage, in the gasification process after the pressure-stabilizing and pressure-reducing valve, the energy release pressure is manually adjusted according to the ambient temperature so that the evaporation temperature corresponding to the energy release pressure is lower than the ambient temperature, thereby realizing that the heat energy required for the gasification process all comes from the air. Gasification can be achieved through a single evaporative cooling, thereby eliminating a large number of cold storage tanks and heat storage tanks, and the absorbed cold energy and heat energy all come from the air, thereby greatly reducing the initial equipment cost and the later operating cost. Due to the different physical properties of the cold energy temperatures generated by the gasification of carbon dioxide at different pressures, energy conversion can be performed according to production needs. Cold energy and electricity can be provided for cooling places and electricity demand places with different temperature requirements in the range of -50°C to 30°C, making the system operation more flexible and more adaptable. For extreme climate areas, phase change cold and heat storage tanks are added to store the heat generated by liquefaction in the phase change cold and heat storage tanks to meet the heat requirements for carbon dioxide gasification, reducing regional limitations. The environmentally adaptive step-down energy storage system of the present invention has a compact structure, low manufacturing cost and use cost, can be self-adjusted according to different use requirements, is flexible to use, and can adapt to extreme environments, with a wide range of applications.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An environmentally adaptive step-down energy storage system, characterized by: The invention comprises an air storage tank, a liquid storage tank and a cold and heat storage unit, wherein the air outlet end of the air storage tank is connected to the liquid storage tank via a first pipeline, a compressor unit and a second heat exchanger are sequentially provided on the first pipeline, the compressor unit comprises a compressor and a first heat exchanger arranged at the rear end of the compressor, the second heat exchanger is connected to an evaporative condenser and is used to convert the medium in the pipe from gas to liquid; the output end of the liquid storage tank is connected to the air storage tank via a second pipeline, a pressure stabilizing and reducing valve, a third heat exchanger and an expansion generator unit are sequentially provided on the second pipeline, the expansion generator unit comprises an expansion generator and a fourth heat exchanger connected in series, the cold and heat storage unit is arranged between the first heat exchanger and the fourth heat exchanger and can realize internal heat exchange, and the third heat exchanger is connected to a cold supply end and can provide cold energy therefor; The output pressure of the pressure stabilizing and reducing valve is adjustable and can make the temperature corresponding to the energy release pressure lower than the current ambient temperature, or reach the cooling temperature required for production and life; It also includes a phase-change cold and heat storage tank, which is arranged between the second heat exchanger and the third heat exchanger. It is used to store the heat generated by the liquefaction of the medium in the second heat exchanger in the phase-change cold and heat storage tank and provide heat for the vaporization of the medium in the third heat exchanger during extreme weather or in extreme weather areas, or to store the cold energy generated by the vaporization of the medium in the third heat exchanger in the phase-change cold and heat storage tank and provide cold energy for the liquefaction of the medium in the second heat exchanger.

2. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: There are multiple compressor groups connected in series.

3. The environmentally adaptive step-down energy storage system according to claim 1, wherein: The compressor unit includes a first-stage compressor, a first heat exchanger I, a second-stage compressor and a first heat exchanger II which are connected in series.

4. The environmentally adaptive step-down energy storage system according to claim 1, wherein: The cold and heat storage unit includes a heat storage tank and a cold storage tank. The output end of the heat storage tank is provided with a first circulation pump, and the output end of the first circulation pump branches into first branches with the same number as the fourth heat exchangers. The first branches are connected to the cold storage tank after respectively exchanging heat through the fourth heat exchangers; the output end of the cold storage tank is provided with a second circulation pump, and the output end of the second circulation pump branches into second branches with the same number as the first heat exchangers. The second branches are connected to the heat storage tank after respectively exchanging heat through the first heat exchangers.

5. The environmentally adaptive step-down energy storage system according to claim 1, wherein: The second heat exchanger is selectively connected to the evaporative condenser or the phase-change cold and heat storage tank, and the third heat exchanger is selectively connected to the cold supply end or the phase-change cold and heat storage tank.

6. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: When the cooling end is for domestic cooling, the pressure-stabilizing and pressure-reducing valve adjusts the medium gasification pressure to 2Mpa-3Mpa; when the cooling end is for industrial cooling, the pressure-stabilizing and pressure-reducing valve adjusts the medium gasification pressure to 0.8Mpa-1.2Mpa.

7. A method for operating an environment-adaptive step-down energy storage system, characterized in that: The following steps are involved: S1. Energy storage: S11. The normal temperature and pressure gaseous medium in the gas storage is compressed in multiple stages by multiple compressors in the compressor unit to form a high temperature and high pressure gaseous medium. Simultaneously, the first heat exchanger in the compressor unit cools the medium in the first pipeline to form a medium temperature and high pressure gaseous medium. S12: The second heat exchanger at the rear end of the compressor unit cools down the medium-temperature and high-pressure gaseous medium in the first pipeline to form a liquid medium, which then passes through the liquefaction buffer tank and enters the liquid storage tank for storage; S13, the medium that is not completely liquefied after cooling is returned to the second heat exchanger through the loop pipe to continue cooling until it is completely liquefied; S2. Energy release: S21: Power generation. Adjust the opening of the pressure-stabilizing and pressure-reducing valve to ensure that the temperature corresponding to the energy release pressure is lower than the current ambient temperature. The medium in the second pipeline is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The medium is then expanded by the expansion generator to generate electricity. Ultimately, the medium in the second pipeline is reduced to a normal temperature and pressure medium and stored in the gas storage bin. S22: Cooling: Adjust the opening of the pressure-stabilizing and pressure-reducing valve to ensure that the temperature corresponding to the energy release pressure reaches the temperature required for production or daily life. The third heat exchanger provides the cooling energy obtained from cooling to the cooling end for production or daily life. The high-pressure and low-temperature gaseous medium after cooling is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium. The gaseous medium is then expanded and generates electricity by the expansion generator, ultimately forming a gaseous medium at normal temperature and pressure and storing it in the gas storage bin. Either step S21 or step S22 is performed.

8. The operating method of the environment-adaptive step-down energy storage system according to claim 7, characterized in that: When in extreme weather and the ambient temperature is lower than the temperature required for the expansion and vaporization of the medium, the second heat exchanger is disconnected from the evaporative condenser and connected to the phase-change cold and heat storage tank. The heat generated by the second heat exchanger for liquefying the medium in the first pipeline is stored in the phase-change cold and heat storage tank and provides heat for the vaporization of the medium in the third heat exchanger.

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