Environment self-adaptive depressurization energy storage system and working method thereof

Abstract

The invention provides an environment self-adaptive depressurization energy storage system which comprises a gas storage bin, a liquid storage tank and a cold and heat storage unit, the gas outlet end of the gas storage bin is connected with the liquid storage tank through a first pipeline, a compressor unit and a second heat exchanger are sequentially arranged on the first pipeline, and the compressor unit comprises a compressor and a first heat exchanger; the second heat exchanger is used for converting a medium in the pipe from a gaseous state into a liquid state; the output end of the liquid storage tank is connected with the gas storage bin through a second pipeline, a pressure stabilizing and reducing valve, a third heat exchanger and an expansion generator set are sequentially arranged on the second pipeline, the expansion generator set comprises an expansion generator and a fourth heat exchanger, and the cold and heat storage unit is arranged between the first heat exchanger and the second heat exchanger and can achieve internal heat exchange. The third heat exchanger is connected with the cold supply end and can provide cold energy. The environment self-adaptive depressurization energy storage system is compact in structure, low in manufacturing cost and use cost, capable of being automatically adjusted according to different use requirements, flexible to use, capable of adapting to extreme environments and wide in application range.

Description

Technical Field

[0001] The present invention relates to an energy storage system, and in particular to an environment-adaptive voltage-reducing 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 the future energy system, especially in promoting the use of renewable energy and improving the stability of the power grid.

[0003] Carbon dioxide energy storage (CES) technology is a new physical energy storage technology based on compressed air energy storage (CAES) and Brayton power generation cycle. As a new technology, carbon dioxide energy storage uses a multi-stage compressor to convert atmospheric pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide during the low electricity price period, and converts electrical energy into the form of carbon dioxide internal energy for storage; during peak electricity consumption, a multi-stage expander is used to expand the high-pressure liquid carbon dioxide into atmospheric pressure gaseous carbon dioxide for power generation, ultimately realizing the storage and release of electrical energy. However, this system has the following disadvantages: 1. Huge cost investment. The whole system includes low-pressure gas storage, high-pressure storage tank, compressor unit, turbine unit, heat exchange system and a large number of cold and heat storage tanks. Especially in the cold storage tank, heat storage tank and heat exchanger, the investment cost of these systems will be very huge, and the cost of technology promotion cannot be ignored.

[0004] 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.

[0005] 3. All energy sources rely on electricity conversion, and the operating costs remain high. Summary of the invention

[0006] Technical issues to be solved The technical problem to be solved by the present invention is to provide an environmentally adaptive step-down energy storage system and a working method thereof which has a compact structure, low equipment cost and use cost, can meet different use requirements, and can adapt to extreme weather and regions. Technical solutions to the problem The present invention provides an environment-adaptive step-down energy storage system, which includes an air storage bin 1, a liquid storage tank 6 and a cold and heat storage unit. The air outlet end of the air storage bin 1 is connected to the liquid storage tank 6 through a first pipeline, and a compressor unit and a second heat exchanger 33 are sequentially arranged 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 bin 1 through a second pipeline, and a pressure-stabilizing and step-down valve 7, a third heat exchanger 34 and an expansion generator unit are sequentially arranged on the second pipeline. The expansion generator unit 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.

[0007] Furthermore, the output pressure of the pressure-stabilizing and 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.

[0008] Furthermore, the gasification temperature at the output end of the pressure-stabilizing and reducing valve 7 is between -50°C and 30°C.

[0009] Furthermore, the compressor groups are multiple and are connected in series.

[0010] Furthermore, the compressor unit includes a primary compressor 21, a first heat exchanger I 31, a secondary compressor 22 and a first heat exchanger II 32 which are connected in series in sequence.

[0011] Furthermore, the expansion generator set includes a plurality of fourth heat exchangers and an expansion generator arranged between two adjacent fourth heat exchangers.

[0012] Furthermore, the expansion generator set includes a fourth heat exchanger I35, a first-stage expansion generator 81, a fourth heat exchanger II36, a second-stage expansion generator 82 and a fourth heat exchanger III37 which are arranged in sequence.

[0013] 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 is branched into first branches with the same number as the fourth heat exchangers, and 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 is branched into second branches with the same number as the first heat exchangers, and the second branches are connected to the heat storage tank 91 after heat exchange through each of the first heat exchangers.

[0014] 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.

[0015] 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 .

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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: S1. Energy storage: S11, the normal temperature and pressure gaseous medium in the gas storage tank 1 is compressed in multiple stages by multiple compressors of the compressor unit to form a high temperature and high pressure gaseous medium, and at the same time, the first heat exchanger in the compressor unit cools down the medium in the first pipeline to form a medium temperature and high pressure gaseous medium; 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 enters the liquid storage tank for storage after passing through the liquefaction buffer tank 5; 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; S2. Energy release: S21, power generation, adjusting the opening of the pressure-stabilizing and pressure-reducing valve 7, and making the temperature corresponding to the energy release pressure lower than the current ambient temperature, heating the medium in the second pipeline through the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium, and then expanding and generating electricity through the expansion generator, and finally making the medium in the second pipeline form a normal temperature and pressure medium and storing it in the gas storage tank 1; S22, take cold, adjust the opening of the pressure-stabilizing and pressure-reducing valve 7, and make the temperature corresponding to the energy release pressure reach the temperature required for production or life, and the third heat exchanger 34 provides the cold energy to the production or life cold supply end; the high-pressure and low-temperature gaseous medium after taking cold is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium, and is expanded and generated by the expansion generator, and finally forms a normal temperature and pressure gaseous medium and is stored in the gas storage bin; Either step S21 or step S22 is performed.

[0020] 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, 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, cold medium is formed and stored in the cold storage tank 92.

[0021] Furthermore, the medium in the gas storage bin 1 and the liquid storage tank 6 is carbon dioxide.

[0022] Furthermore, the second heat exchanger 33 is connected to an evaporative condenser 41 and can exchange heat with air to generate cold.

[0023] Furthermore, energy is stored at night when electricity prices are low, and energy is released during the day when electricity prices are high.

[0024] 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 liquefying 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.

[0025] Furthermore, the temperature of the medium in the liquid storage tank 6 is higher than the ambient night temperature.

[0026] Furthermore, the compressor unit can compress the 0.1Mpa room temperature gaseous medium in the gas storage bin 1 into a 7Mpa-8Mpa gaseous medium at 35℃-45℃, and cool the medium through the second heat exchanger 33 to form an isobaric liquid medium at 25℃-35℃.

[0027] Beneficial Effects The environmentally adaptive step-down energy storage system of the present invention optimizes the single electricity-to-electricity conversion energy storage form of traditional carbon dioxide energy storage, abandons a large number of energy conversion methods in the form of cold and heat storage, and replaces them with a lightweight equipment that can adaptively adjust the energy release pressure according to the ambient temperature. The energy extraction mode can be flexibly converted 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 characteristics 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 is all derived from the air. Gasification can be achieved through a single evaporative cooling, thereby saving a large number of cold storage tanks and heat storage tanks, and the absorbed cold energy and heat energy are all derived from the air, thereby greatly reducing the initial equipment cost and the later operating cost. According to the different physical properties of the cold energy temperatures generated by the gasification of carbon dioxide under different pressures, energy conversion can be performed according to production needs, and 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 more flexible and 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 for the heat required for carbon dioxide gasification, thereby 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

[0028] Figure 1 A connection diagram of the environment-adaptive step-down energy storage system of the present invention; In the figure: 1. gas storage bin, 21. primary compressor, 22. secondary 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. primary expansion generator, 82. secondary expansion generator, 91. heat storage tank, 92. cold storage tank 92. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] See also Figure 1 The present invention provides an environment-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, and a compressor unit and a second heat exchanger 33 are sequentially arranged 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 groups, which are sequentially connected in series to achieve multi-stage compression. The compressor is used to compress the gaseous medium to 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 (carbon dioxide) in the pipe from gas to liquid, and store it in the liquid form in the liquid storage tank 6. In this embodiment, the condenser is an evaporative condenser 41, or an evaporative cooler, which can exchange heat with air. The above-mentioned first pipeline is used as an energy storage pipeline.

[0031] 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 pressure-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 in 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 third heat exchanger 34 provides it with cold energy of -10°C to 5°C; when the cold supply end is an industrial cold supply end, the third heat exchanger 34 provides it with cold energy of -45°C to -35°C. The above-mentioned second pipeline serves as an energy release pipeline.

[0032] 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.

[0033] 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 arranged. 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. The 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 (receiving) 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 connected to the evaporative condenser 41 or the phase-change cold and heat storage tank 42, and the third heat exchanger 34 is connected to the cold supply end or the phase-change cold and heat storage tank 42.

[0034] The cold and heat storage unit includes a heat storage tank 91 and a cold storage tank 92. A first circulation pump is provided at the output end of the heat storage tank 91. The output end of the first circulation pump is branched into a first branch. The number of the first branches is the same as the number of the fourth heat exchangers and corresponds one to one. The first branch is connected to the cold storage tank 92 after heat exchange through each fourth heat exchanger; a second circulation pump is provided at the output end of the cold storage tank 92. The output end of the second circulation pump is branched into a second branch. The number of the second branches is the same as the number of the first heat exchangers and corresponds one to one. The second branch is connected to the heat storage tank 91 after heat exchange through each first heat exchanger.

[0035] 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.

[0036] The following is a detailed description of the energy storage system for this application: The whole system comprises 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. A first compressor 21, a first heat exchanger I 31, a second 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 conveying direction of the medium on the first pipeline. The second heat exchanger 33 is used to liquefy the medium in the first pipeline. The temperature of the medium is reduced to convert the medium from gaseous state to liquid state to be 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 state, 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 to fully convert it into liquid state. 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. A pressure-stabilizing and pressure-reducing valve 7, a third heat exchanger 34, 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 are sequentially arranged along the medium conveying direction on the second pipeline. The third heat exchanger 34 is simultaneously connected to the cold end and the phase-change cold and heat storage tank 42, 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 use requirements. At the same time, the opening of the pressure-stabilizing and pressure-reducing valve 7 is adjustable, so as to form 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 air conditioner in the residential community, the vaporization pressure can be adjusted to about 2.5Mpa, and its vaporization temperature at 2.The vaporization temperature of 5Mpa is about -12°C, 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°C to 30°C, 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 make it 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 is branched into three first branches, and the three first branches are respectively connected to The fourth heat exchanger I35, the fourth heat exchanger II36 and the fourth heat exchanger III37 are connected to realize heat exchange, which can increase the temperature of the medium in the second pipeline and increase the power generation. At the same time, after heat exchange, the temperature of the medium in the first branch is reduced to form a low-temperature medium, which is transported to the cold storage tank 92; the second circulation pump at the output end of the cold storage tank 92 is branched into two second branches, which are respectively connected to the first heat exchanger I31 and the first heat exchanger II32 to cool the medium in the first pipeline and pre-cool it for the next step of liquefaction. At the same time, after heat exchange, the temperature of the medium in the second branch is increased to form a high-temperature medium, which is transported to the heat storage tank 91. .

[0037] When the environmentally adaptive step-down energy storage system of the present application is working, it mainly includes energy storage and energy release.

[0038] The following is a brief description: Energy storage process: At night when electricity prices are low, normal temperature and 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, the evaporative condenser 41, and the high-power liquefaction latent heat comes entirely from the air, realizing the liquefaction process of air cooling, and 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 the liquefaction is stored in the phase change cold and heat storage tank 42 through the second heat exchanger 33.

[0039] 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.

[0040] 1. Energy release for 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 heat up through the fourth heat exchanger I35 and the fourth heat exchanger II36. The heated high-temperature and high-pressure gaseous carbon dioxide is expanded by the generator to generate electricity, and finally becomes 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.

[0041] 2. Releasing energy to obtain cold: 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 temperature required for production. 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 1Mpa, and its gasification temperature at 1Mpa 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 2.5Mpa, and its gasification temperature at 2.5Mpa 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 high-temperature and high-pressure gaseous carbon dioxide after the heating is expanded to generate electricity, and finally becomes normal-pressure gaseous carbon dioxide and is stored in the gas storage bin 1; and the cold energy generated during the expansion process is also stored in the cold storage tank 92, and is heated by heat exchange with the heat energy generated by compression.

[0042] 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: S1. Energy storage: S11, the normal temperature and pressure gaseous medium (carbon dioxide) in the gas storage tank 1 is compressed in multiple stages by multiple compressors of the compressor unit to form a high temperature and high pressure gaseous medium, and at the same time, the first heat exchanger in the compressor unit cools down the medium in the first pipeline to form a medium temperature and high pressure gaseous medium; 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 enters the liquid storage tank 6 for storage after passing through the liquefaction buffer tank 5. The second heat exchanger 33 is connected to an evaporative condenser 41 and can exchange heat with air to obtain cold; In this embodiment, the compressor unit can compress the 0.1Mpa normal temperature gaseous medium in the gas storage bin into a 7Mpa-8Mpa high temperature gaseous medium, and at the same time, dissipate heat through the first heat exchanger to form a 35°C-45°C gaseous medium, that is, a medium temperature gaseous medium, preferably, compressed into a 7.3Mpa 40°C gaseous medium, and cool the state medium through the second heat exchanger 33 to form an isobaric 25°C-35°C liquid medium, the second heat exchanger 33 exchanges heat with the ambient temperature below 31°C at night through evaporative cooling, preferably, cools to form a 7.3Mpa 31°C liquid medium; 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, the hot medium is formed and stored in the heat storage tank 91; S13, the medium that is not completely liquefied after being cooled returns to the second heat exchanger 33 through the loop pipe 51 to continue to be cooled until it is completely liquefied; The above energy storage process is carried out at night when electricity prices are low; S2. Energy release: S21, power generation mode, adjust the opening of the pressure-stabilizing and pressure-reducing valve 7, and make the temperature corresponding to the energy release pressure lower than the current ambient temperature, and heat the medium in the second pipeline through the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium, and then expand and generate electricity through the expansion generator, and finally make the medium in the second pipeline form a normal temperature and pressure medium and store it in the gas storage tank 1; S22, cooling mode, adjust the opening of the pressure-stabilizing and pressure-reducing valve 7, and make the temperature corresponding to the energy release pressure reach the temperature required for production or life, and the third heat exchanger 34 provides the cold energy to the production or life cooling end; 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, and is expanded and generated by the expansion generator, and finally forms a normal temperature and pressure gaseous medium and 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 make the medium at the end of the second pipeline tend to normal temperature and store it in the gas storage bin 1; 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 the medium in the second pipeline is heated to form a cold medium after the heat exchange, which is stored in the cold storage tank 92; The above-mentioned high pressure, medium pressure and low pressure are relative pressures, and the high temperature, medium temperature and low temperature are relative temperatures.

[0043] 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 a suitable energy release pressure and vaporization temperature.

[0044] When it is extreme weather or in extreme weather areas, and the ambient temperature is lower than the temperature required for the medium to expand and vaporize, 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.

[0045] The environmentally adaptive step-down energy storage system of the present invention optimizes the single electricity-to-electricity conversion energy storage form of traditional carbon dioxide energy storage, abandons a large number of energy conversion methods in the form of cold and heat storage, and replaces them with a lightweight equipment that can adaptively adjust the energy release pressure according to the ambient temperature. The energy extraction mode can be flexibly converted 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 characteristics 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 is all derived from the air. Gasification can be achieved through a single evaporative cooling, thereby saving a large number of cold storage tanks and heat storage tanks, and the absorbed cold energy and heat energy are all derived from the air, thereby greatly reducing the initial equipment cost and the later operating cost. According to the different physical properties of the cold energy temperatures generated by the gasification of carbon dioxide under different pressures, energy conversion can be performed according to production needs, and 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 more flexible and 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 for the heat required for carbon dioxide gasification, thereby 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.

[0046] 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 the scope of protection of the present invention.

Claims

1. An environment-adaptive step-down energy storage system, characterized in that: It includes an air storage bin, a liquid storage tank and a cold and heat storage unit, the air outlet end of the air storage bin is connected to the liquid storage tank through a first pipeline, a compressor unit and a second heat exchanger are arranged in sequence 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 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 bin through a second pipeline, a pressure stabilizing and reducing valve, a third heat exchanger and an expansion generator unit are arranged in sequence on the second pipeline, the expansion generator unit 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 is connected to a cold supply end and can provide cold energy for it.

2. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: The output pressure of the pressure-stabilizing and pressure-reducing valve 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.

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

4. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: The compressor unit comprises a primary compressor, a first heat exchanger I, a secondary compressor and a first heat exchanger II which are connected in series in sequence.

5. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: 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, the output end of the first circulation pump is branched into first branches with the same number as the fourth heat exchangers, and the first branches are connected to the cold storage tank after heat exchange through each of the fourth heat exchangers; the output end of the cold storage tank is provided with a second circulation pump, the output end of the second circulation pump is branched into second branches with the same number as the first heat exchangers, and the second branches are connected to the heat storage tank after heat exchange through each of the first heat exchangers.

6. The environmentally adaptive step-down energy storage system according to claim 1, characterized in that: It also includes a phase-change cold and heat storage tank, which is arranged between the second heat exchanger and the third heat exchanger, and 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.

7. The environment-adaptive step-down energy storage system according to claim 6, characterized in that: 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.

8. The environment-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.

9. A working method of 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 bin is compressed in multiple stages by multiple compressors of the compressor unit to form a high temperature and high pressure gaseous medium, and at the same time, the first heat exchanger in the compressor unit cools down 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 enters the liquid storage tank for storage after passing through the liquefaction buffer tank; 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, adjusting the opening of the pressure stabilizing and reducing valve, and making the temperature corresponding to the energy release pressure lower than the current ambient temperature, heating the medium in the second pipeline through the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium, and then expanding and generating electricity through the expansion generator, finally making the medium in the second pipeline form a normal temperature and pressure medium and storing it in the gas storage bin; S22, take cold, adjust the opening of the pressure-stabilizing and pressure-reducing valve, and make the temperature corresponding to the energy release pressure reach the temperature required for production or life, and the third heat exchanger provides the cold energy to the production or life cold supply end; the high-pressure and low-temperature gaseous medium after taking cold is heated by the fourth heat exchanger to form a high-temperature and high-pressure gaseous medium, and is expanded and generated by the expansion generator, and finally forms a normal temperature and pressure gaseous medium and is stored in the gas storage bin; Either step S21 or step S22 is performed.

10. The working method of the environment-adaptive step-down energy storage system according to claim 9, characterized in that: When in extreme weather and the ambient temperature is lower than the temperature required for the medium to expand and vaporize, the second heat exchanger is disconnected from the evaporative condenser and connected to the phase-change cold and heat storage tank, and 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 heat is provided for the vaporization of the medium in the third heat exchanger.

Images