Total energy recovery type CO2 energy storage system

Abstract

The utility model relates to a total energy recovery type CO2 energy storage system, and belongs to the field of energy storage. Comprising a CO2 energy storage unit, and the CO2 energy storage unit comprises a low-pressure gas storage cabinet, a gas compressor, a condenser, a high-pressure storage tank, an evaporator and a turbine which are sequentially arranged in the flowing direction of gaseous or liquid CO2; the interstage cooler is bidirectionally connected to the gas compressor, so that the gas compressor can compress the gaseous CO2 again; and the reheater is bidirectionally connected to the turbine, so that the gaseous CO2 can do work on the turbine again. The energy storage system further comprises an oil heat storage unit, a water heat storage unit and a heat pump unit. During energy storage, the oil heat storage unit, the water heat storage unit and the heat pump unit store compression heat of gaseous CO2 and condensation heat of gaseous CO2. During energy release, the oil heat storage unit and the water heat storage unit provide evaporation heat required by the liquid CO2. According to the utility model, not only can the condensation latent heat of gaseous CO2 in the energy storage process be improved, but also the heat in the CO2 energy storage process and the CO2 energy release process can be comprehensively recovered, and the energy storage efficiency of the system is improved.

Description

Technical Field

[0001] The utility model belongs to the field of energy storage and relates to a full energy recovery type CO2 energy storage system. Background Art

[0002] With the development of new energy technology, my country's renewable energy installed capacity accounts for 47.3% of the country's total installed capacity, and annual power generation accounts for 31.6% of the total electricity consumption. However, the new energy system has the characteristics of rapid fluctuations and difficulty in absorption. How to maintain the stability of the power system has become an urgent problem to be solved.

[0003] Equipping new energy systems with energy storage systems is the key to addressing stability issues. Among the many energy storage technologies, pumped storage, chemical battery storage, and compressed air storage are the main technologies that can achieve megawatt-scale applications. However, pumped storage must be built in non-severely cold areas with suitable terrain differences and abundant water sources, and is subject to high restrictions on geographical conditions; chemical battery storage faces constraints in terms of economy, safety, cycle life, and waste battery treatment; compressed air storage has the advantages of being green, safe, and long-life, but traditional compressed air storage is heavily dependent on geographical conditions and has low energy storage density.

[0004] As a new type of compressed gas energy storage technology, CO2 energy storage has many advantages, such as excellent physical properties of energy storage fluids, stable system performance, and compact process equipment. CO2 energy storage uses the heat energy absorbed or released by the phase change process of CO2 gas and liquid to store or release electrical energy. Specifically, when the power generation of new energy is greater than the power consumption or energy storage is needed during the valley period of electricity prices, the CO2 energy storage system uses the power of the power grid to compress gaseous CO2 to form high-pressure liquid CO2 storage, thereby storing energy; when the power grid is insufficient or electricity is needed during the peak period of electricity prices, the high-pressure liquid CO2 evaporates into high-pressure gaseous CO2 and works on the turbine to generate electricity, thereby releasing energy.

[0005] However, in the process of energy storage, low-temperature gaseous CO2 is compressed to produce medium-low-temperature and high-pressure gaseous CO2, and the ambient cold is used to cool the medium-low-temperature and high-pressure CO2 to liquid state, and the condensation latent heat of this process is used as the heat of vaporization of liquid CO2 into gaseous CO2 during the energy release process. However, since there is a certain amount of heat loss in each link of the thermal system, the condensation latent heat of gaseous CO2 cannot be fully used for the vaporization heat of liquid CO2, which makes the gaseous CO2 obtained by vaporization do low work on the turbine. It can be seen that the existing CO2 energy storage system has the problem of low system energy storage efficiency due to insufficient utilization or waste of condensation latent heat. Utility Model Content

[0006] In view of this, the utility model provides a full energy recovery type CO2 energy storage system. One purpose is to increase the condensation latent heat of gaseous CO2 in the energy storage process, and fully convert the condensation latent heat into the vaporization heat of liquid CO2 in the energy release process, thereby improving the power generation efficiency and ultimately improving the energy storage efficiency of the system; the second purpose is to make full use of the heat during the phase change in the CO2 energy storage process and the energy release process, comprehensively recover the heat of the phase change process, and improve the energy storage efficiency of the system.

[0007] To achieve the above-mentioned purpose, the utility model provides a full energy recovery type CO2 energy storage system, including a CO2 energy storage unit, the CO2 energy storage unit includes a low-pressure gas storage cabinet, a compressor, a condenser, a high-pressure storage tank, an evaporator and a turbine arranged in sequence along the flow direction of gaseous or liquid CO2.

[0008] When the system stores energy, low-pressure gaseous CO2 flows out of the low-pressure gas storage tank, is compressed by the compressor to form high-pressure gaseous CO2, and then is liquefied through the condenser to form high-pressure liquid CO2 and stored in the high-pressure storage tank; when the system releases energy, high-pressure liquid CO2 flows out of the high-pressure storage tank, is vaporized by the evaporator to form high-pressure gaseous CO2, and then drives the turbine to generate electricity, and is finally stored in the low-pressure gas storage tank in the form of low-pressure gaseous CO2.

[0009] Optionally, the CO2 energy storage unit also includes an interstage cooler and a reheater. The interstage cooler is bidirectionally connected to the compressor. The high-temperature and high-pressure gaseous CO2 formed after the compressor compresses the low-pressure gaseous CO2 is cooled in the interstage cooler and then returned to the compressor for recompression; the reheater is bidirectionally connected to the turbine. The medium- and low-temperature gaseous CO2 formed after the high-temperature gaseous CO2 works on the turbine is heated in the reheater and then returned to the turbine to work again.

[0010] Optionally, the CO2 energy storage unit further includes a superheater and an after-stage cooler. The after-stage cooler is arranged between the compressor and the condenser to cool the high-temperature and high-pressure gaseous CO2 produced by the compressor; the superheater is arranged between the evaporator and the turbine to heat the low-temperature and high-pressure gaseous CO2 produced by the evaporator.

[0011] Optionally, a regenerator is provided between the turbine and the low-pressure gas storage tank, and the medium-low-temperature and low-pressure gaseous CO2 after the turbine has done work is cooled by the regenerator to form low-temperature and low-pressure gaseous CO2 and stored in the low-pressure gas storage tank.

[0012] Optionally, the energy storage system further includes an oil heat storage unit, which includes a high-temperature heat-conducting oil tank and a low-temperature heat-conducting oil tank.

[0013] Optionally, the outlet of the low-temperature heat transfer oil tank is connected to the heat exchange inlet of the interstage cooler and the heat exchange inlet of the after-stage cooler, and the inlet of the high-temperature heat transfer oil tank is connected to the heat exchange outlet stage of the interstage cooler and the heat exchange outlet of the cooler. The low-temperature heat transfer oil in the low-temperature heat transfer oil tank flows to the interstage cooler and the after-stage cooler respectively to absorb the heat of the gaseous CO2 in the interstage cooler and the after-stage cooler, and form high-temperature heat transfer oil to flow to the high-temperature heat transfer oil tank.

[0014] Optionally, the outlet of the high-temperature heat transfer oil tank is connected to the heat exchange inlet of the superheater and the heat exchange inlet of the reheater, and the inlet of the low-temperature heat transfer oil tank is connected to the heat exchange outlet of the superheater and the heat exchange outlet of the reheater. The high-temperature heat transfer oil in the high-temperature heat transfer oil tank flows to the reheater and the superheater respectively to heat the gaseous CO2 in the reheater and the superheater, and form low-temperature heat transfer oil to flow to the low-temperature heat transfer oil tank.

[0015] Optionally, the CO2 energy storage system provided by the utility model further includes a heat pump unit, and the heat pump unit includes a compressor and a heat pump condenser.

[0016] Optionally, the inlet of the compressor is connected to the heat exchange outlet of the condenser, and its outlet is connected to the heat pump condenser. The heat pump working medium absorbs the heat released when the gaseous CO2 is liquefied in the condenser and heats up, and then is compressed by the compressor into a high-temperature and high-pressure working medium and transported to the heat pump condenser.

[0017] Optionally, the outlet of the heat pump condenser is connected to the heat exchange inlet of the condenser, and the low-temperature and low-pressure working medium cooled by the heat pump condenser is transported to the condenser, wherein a throttle valve is provided on the connecting passage between the outlet of the heat pump condenser and the condenser.

[0018] Optionally, the CO2 energy storage system provided by the present invention further includes a water heat storage unit, and the water heat storage unit includes a hot water storage tank bidirectionally connected to the heat pump condenser.

[0019] Optionally, the low-temperature water outlet of the hot water storage tank is connected to the heat exchange inlet of the heat pump condenser, and the heat exchange outlet of the heat pump condenser is connected to the high-temperature water inlet of the hot water storage tank. The low-temperature water flows from the hot water storage tank to the heat pump condenser, absorbs the heat of the high-temperature and high-pressure working medium in the heat pump condenser, forms high-temperature water and returns to the hot water storage tank.

[0020] Optionally, the heat storage tank is also bidirectionally connected to the evaporator, the high-temperature water outlet of the heat storage tank is connected to the heat exchange inlet of the evaporator, and the heat exchange outlet of the evaporator is connected to the low-temperature water inlet of the heat storage tank. The high-temperature water flows from the heat storage tank to the evaporator to provide heat for the vaporization of liquid CO2 in the evaporator, and the low-temperature water formed after the evaporator absorbs heat returns to the heat storage tank.

[0021] Optionally, the low-temperature water outlet of the heat storage tank is also connected to the heat exchange inlet of the regenerator to absorb the heat of the medium and low-temperature gaseous CO2 in the regenerator; the heat exchange outlet of the regenerator is connected to the heat exchange inlet of the evaporator to introduce the formed high-temperature water into the evaporator.

[0022] Optionally, the compressor is connected to an electric motor and the turbine is connected to a generator.

[0023] Optionally, an integrated generator is used as the motor of the compressor and the generator of the turbine respectively, the energy storage process is used as a motor, and the energy release process is used as a generator.

[0024] Optionally, the low-pressure gas storage tank is a fiberglass gas storage tank or a steel structure gas storage tank, and the compressor is an axial flow or centrifugal compressor.

[0025] The beneficial effects of the utility model are:

[0026] The carbon dioxide energy storage system provided by the utility model is provided with an interstage cooler bidirectionally connected to the compressor to cool the heated high-pressure gaseous CO2 after the initial compression of the compressor, and return the cooled high-pressure gaseous CO2 to the compressor for recompression, thereby increasing the density of the compressed CO2, and finally making the high-pressure CO2 after the energy storage has been completed have a higher condensation latent heat, thereby improving the energy storage efficiency. During the energy storage process, the heat pump unit, the oil heat storage unit and the water heat storage unit can store the compression heat of the multiple compressions of the gaseous CO2 and the liquefaction heat of the gaseous CO2, and convert them into the evaporation heat required for evaporating the liquid CO2 during the energy release process and the heat required for heating the gaseous CO2 that performs work on the turbine multiple times. It can be seen that the energy storage system provided by the utility model can fully convert the condensation heat in the energy storage process into the vaporization heat in the energy release process, and can also make full use of the heat when the CO2 undergoes phase change, and recover the full energy of the energy storage and energy release processes, thereby improving the energy storage efficiency.

[0027] The energy storage system provided by the utility model couples the CO2 energy storage system and the heat pump system, and uses the condensation heat release of gaseous CO2 to provide a heat source for the heat pump, which can effectively reduce the construction investment under the premise of ensuring the stable condensation and liquefaction of carbon dioxide. Furthermore, the utility model adopts a low-pressure gas storage cabinet, so that the gas storage working pressure can be adjusted, and it can also effectively reduce the floor space.

[0028] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and will be apparent to those skilled in the art based on the following examination and research, or can be taught from the practice of the present invention to some extent. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be described in detail below in conjunction with the accompanying drawings, in which:

[0030] Figure 1 A schematic diagram of the structure of the full energy recovery CO2 energy storage system provided by the utility model;

[0031] Figure 2 A detailed diagram of the processing flow of the full energy recovery CO2 energy storage system provided by the utility model.

[0032] Reference numerals:

[0033] 1- low-pressure gas storage cabinet, 2- compressor, 3- interstage cooler, 4- stage aftercooler, 5- condenser, 6- high-pressure storage tank, 7- evaporator, 8- superheater, 9- turbine, 10- recuperator, 11- reheater; 12- high-temperature thermal oil tank, 13- low-temperature thermal oil tank, 14- hot water storage tank, 15- compressor, 16- heat pump condenser, 17- throttle valve; 18- CO2 energy storage unit; 19- oil heat storage unit; 20- water heat storage unit; 21- heat pump unit. DETAILED DESCRIPTION

[0034] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. The following embodiments and the features in the embodiments can be combined with each other without conflict.

[0035] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present utility model. In order to better illustrate the embodiments of the present utility model, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0036] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0037] In order to achieve the above-mentioned purpose, the utility model provides a full energy recovery type CO2 energy storage system, such as Figure 1 As shown, it includes a CO2 energy storage unit 18, an oil heat storage unit 19, a water heat storage unit 20 and a heat pump unit 21.

[0038] The CO2 energy storage unit 18 includes a low-pressure gas storage tank 1, a compressor 2, a condenser 5, a stage aftercooler 4, a high-pressure storage tank 6, an evaporator 7, a superheater 8 and a turbine 9, which are arranged in sequence along the flow direction of gaseous or liquid CO2. The compressor 2 is connected to an electric motor, and the turbine 9 is connected to a generator. The inspired integrated generator is used as the electric motor connected to the compressor 2 and the generator connected to the turbine 9, respectively. The energy storage process is used as a motor, and the energy release process is used as a generator. The low-pressure gas storage tank 1 is preferably a glass fiber reinforced plastic gas storage tank or a steel structure gas storage tank, and its gas storage pressure is adjustable, which can realize variable pressure storage, avoid heat loss during insulation, and thus increase energy recovery efficiency; the compressor 2 is preferably an axial flow or centrifugal compressor 15. The stage aftercooler 4 is used to cool the high-temperature and high-pressure gaseous CO2 generated by the compressor 2, and the superheater 8 is used to heat the low-temperature and high-pressure gaseous CO2 generated by the evaporator 7.

[0039] Furthermore, the interstage cooler 3 is bidirectionally connected to the compressor 2. The heated high-pressure gaseous CO2 formed after the compressor 2 compresses the low-pressure gaseous CO2 is cooled in the interstage cooler 3 and then returned to the compressor 2 for recompression, thereby increasing the mass of CO2 per unit volume and increasing the density of CO2, which is conducive to further compressing the gaseous CO2, thereby saving compression energy consumption. The reheater 11 is bidirectionally connected to the turbine 9. The medium-low temperature gaseous CO2 formed after the high-temperature gaseous CO2 works on the turbine 9 is heated in the reheater 11 and then returned to the turbine 9 for re-work, so as to make full use of the internal energy of the gaseous CO2 and improve the power generation efficiency. A regenerator 10 is also arranged between the turbine 9 and the low-pressure gas storage tank 1. The medium-low temperature and low-pressure gaseous CO2 after the turbine 9 works is cooled by the regenerator to form a low-temperature and low-pressure gaseous CO2 and stored in the low-pressure gas storage tank 1. The oil heat storage unit 19 includes a high-temperature heat transfer oil tank 12 and a low-temperature heat transfer oil tank 13.

[0040] The outlet of the low-temperature heat transfer oil tank 13 is connected to the heat exchange inlet of the interstage cooler 3 and the heat exchange inlet of the after-stage cooler 4, and the inlet of the high-temperature heat transfer oil tank 12 is connected to the heat exchange outlet of the interstage cooler 3 and the heat exchange outlet of the after-stage cooler 4. The low-temperature heat transfer oil in the low-temperature heat transfer oil tank 13 flows to the interstage cooler 3 and the after-stage cooler 4 respectively to absorb the heat of the gaseous CO2 in the interstage cooler 3 and the after-stage cooler 4, and form high-temperature heat transfer oil to flow to the high-temperature heat transfer oil tank 12. The outlet of the high-temperature heat transfer oil tank 12 is connected to the heat exchange inlet of the superheater 8 and the heat exchange inlet of the reheater 11, and the inlet of the low-temperature heat transfer oil tank 13 is connected to the heat exchange outlet of the superheater 8 and the heat exchange outlet of the reheater 11. The high-temperature heat transfer oil in the high-temperature heat transfer oil tank 12 flows to the reheater 11 and the superheater 8 respectively to heat the gaseous CO2 in the reheater 11 and the superheater 8, and form low-temperature heat transfer oil to flow to the low-temperature heat transfer oil tank 13.

[0041] The heat pump unit 21 includes a compressor 15 and a heat pump condenser 16. The inlet of the compressor 15 is connected to the heat exchange outlet of the condenser 5 of the CO2 energy storage unit 18, and its outlet is connected to the heat pump condenser 16. The heat pump working medium absorbs the heat released when the gaseous CO2 is liquefied in the condenser 5 and heats up, and then is compressed into a high-temperature and high-pressure working medium by the compressor 15 and transported to the heat pump condenser 16. The outlet of the heat pump condenser 16 is connected to the heat exchange inlet of the condenser 5, and the low-temperature and low-pressure working medium cooled by the heat pump condenser 16 is transported to the condenser 5. A throttle valve 17 is provided on the connection passage between the outlet of the heat pump condenser 16 and the condenser 5.

[0042] The water heat storage unit 20 includes a hot water storage tank 14 bidirectionally connected to the heat pump condenser 16. The low-temperature water outlet of the hot water storage tank 14 is connected to the heat exchange inlet of the heat pump condenser 16, and the heat exchange outlet of the heat pump condenser 16 is connected to the high-temperature water inlet of the hot water storage tank 14. Low-temperature water flows from the hot water storage tank 14 to the heat pump condenser 16, absorbs the heat of the high-temperature and high-pressure working medium in the heat pump condenser 16 to form high-temperature water and returns to the hot water storage tank 14. The hot water storage tank 14 is also bidirectionally connected to the evaporator 7 of the CO2 energy storage unit 18, the high-temperature water outlet of the hot water storage tank 14 is connected to the heat exchange inlet of the evaporator 7, the heat exchange outlet of the evaporator 7 is connected to the low-temperature water inlet of the hot water storage tank 14, and the high-temperature water flows from the hot water storage tank 14 to the evaporator 7 to provide heat for the vaporization of liquid CO2 in the evaporator 7, and the low-temperature water formed after the evaporator 7 absorbs heat returns to the hot water storage tank 14. The low-temperature water outlet of the hot water storage tank 14 is also connected to the heat exchange inlet of the regenerator 10 of the CO2 energy storage unit 18 to absorb the heat of the high-temperature gaseous CO2 in the regenerator 10; the heat exchange outlet of the regenerator 10 is connected to the heat exchange inlet of the evaporator 7 to introduce the formed high-temperature water into the evaporator 7.

[0043] like Figure 2As shown, when the amount of electricity generated by new energy is greater than the amount of electricity consumed or during the valley period of electricity prices, the CO2 energy storage system enters the energy storage process. The CO2 energy storage system is powered off from the grid, and the low-pressure and low-temperature gaseous CO2 flows out of the low-pressure gas storage cabinet 1. The motor drives the compressor 2 to work and compress the low-pressure and low-temperature gaseous CO2 to form a heated and high-pressure gaseous CO2, and transport it to the interstage cooler 3 for cooling. The compressor 2 re-compresses the cooled high-pressure gaseous CO2 to increase the temperature of the compressed CO2, thereby increasing the latent heat of condensation. The high-temperature and high-pressure gaseous CO2 formed after the compressor 2 is re-compressed flows from the last-stage impeller of the compressor 2 to the after-stage cooler 4, and after being cooled by the after-stage cooler 4, it forms a low-temperature and high-pressure gaseous CO2, and then enters the condenser 5 to liquefy into a low-temperature and high-pressure liquid CO2 and is stored in the high-pressure storage tank 6.

[0044] During the energy storage process, the oil heat storage unit 19, the water heat storage unit 20, and the heat pump unit 21 are all operated synchronously to store the compression heat of the gaseous CO2 and the condensation heat of the gaseous CO2.

[0045] During the energy storage process, the heat released by the compressor 2 when compressing the gaseous CO2 is stored by the oil heat storage unit 19. Specifically, the stage aftercooler 4 absorbs the compression heat released by the compressor 2, and the low-temperature heat transfer oil in the low-temperature heat transfer oil tank 13 enters the stage aftercooler 4, absorbs heat to form high-temperature heat transfer oil and flows back to the high-temperature heat transfer oil tank 12 for storage.

[0046] During the energy storage process, the heat absorbed by the gaseous CO2 after cooling and heating in the interstage cooler 3 is stored by the heat storage unit. Specifically, the low-temperature heat transfer oil in the low-temperature heat transfer oil tank 13 enters the interstage cooler 3, absorbs the heat of the heated high-pressure gaseous CO2 to form high-temperature heat transfer oil and flows back to the high-temperature heat transfer oil tank 12 for storage.

[0047] During the energy storage process, the heat released when the gaseous CO2 is liquefied in the condenser 5 is stored by the heat pump unit 21 and the water heat storage unit 20. Specifically, the working medium of the heat pump absorbs liquefaction and releases heat in the condenser 5. The working medium after absorbing heat and heating is compressed into a high-temperature and high-pressure working medium in the compressor 15, and then enters the heat pump condenser 16. The low-temperature water in the hot water storage tank 14 is converted into high-temperature water after heat exchange with the high-temperature and high-pressure working medium in the heat pump condenser 16, and the high-temperature water flows back to the hot water storage tank 14 for storage. The high-temperature and high-pressure working medium is converted into a low-temperature and low-pressure working medium after heat exchange in the heat pump condenser 16, and then enters the condenser 5 again to absorb heat.

[0048] like Figure 2As shown, when the power grid is insufficient or at the peak electricity price, the CO2 energy storage system enters the energy release process. Low-temperature and high-pressure liquid CO2 flows out of the high-pressure storage tank 6, and is vaporized by the evaporator 7 to form low-temperature and high-pressure gaseous CO2, which is then heated again by the superheater 8 to form high-temperature and high-pressure gaseous CO2. The high-temperature and high-pressure gaseous CO2 drives the turbine 9 to work and generate electricity, so that the system can output electrical energy. After the high-temperature and high-pressure gaseous CO2 works on the turbine 9, it forms medium- and low-temperature gaseous CO2, and its energy is not fully utilized. The medium- and low-temperature gaseous CO2 is heated again by the reheater 11 to form high-temperature gaseous CO2, and drives the turbine 9 to work again. After working multiple times, the high-temperature and low-pressure gaseous CO2 is cooled by the regenerator 10 and stored in the low-pressure gas storage cabinet 1 in the form of low-temperature and low-pressure gaseous CO2.

[0049] During the energy release process, the oil heat storage unit 19 and the water heat storage unit 20 are operated synchronously to provide the evaporation heat required for the liquid CO2.

[0050] In the energy release process, the heat that needs to be absorbed by the evaporator 7 when evaporating the low-temperature and high-pressure liquid CO2 is provided by the water heat storage unit 20. Specifically, the high-temperature water in the hot water storage tank 14 enters the evaporator 7, and the evaporator 7 uses the heat of the high-temperature water to evaporate the liquid CO2. The low-temperature water formed after releasing the heat flows back to the hot water storage tank 14 for storage.

[0051] In the energy release process, the heat that needs to be absorbed by the superheater 8 when heating the low-temperature and high-pressure gaseous CO2 is provided by the oil heat storage unit 19. Specifically, the high-temperature heat transfer oil in the high-temperature heat transfer oil tank 12 enters the superheater 8, and the superheater 8 uses the heat of the high-temperature heat transfer oil to heat the low-temperature gaseous CO2. The low-temperature heat transfer oil formed after releasing the heat flows back to the low-temperature heat transfer oil tank 13 for storage.

[0052] In the energy release process, the heat required to be absorbed by the reheater 11 when heating the medium and low temperature gaseous CO2 is provided by the oil heat storage unit 19. Specifically, the high temperature heat transfer oil in the high temperature heat transfer oil tank 12 enters the reheater 11, and the reheater 11 uses the heat of the high temperature heat transfer oil to heat the medium and low temperature gaseous CO2. The low temperature heat transfer oil formed after releasing the heat flows back to the low temperature heat transfer oil tank 13 for storage.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the utility model.

Claims

1. A full energy recovery type CO2 energy storage system, comprising a CO2 energy storage unit (18), wherein the CO2 energy storage unit (18) comprises a low-pressure gas storage cabinet (1), a compressor (2), a condenser (5), a high-pressure storage tank (6), an evaporator (7) and a turbine (9) arranged in sequence along the flow direction of gaseous or liquid CO2; When the system stores energy, low-pressure gaseous CO2 flows out of the low-pressure gas storage tank (1), is compressed by the compressor (2) to form high-pressure gaseous CO2, and then liquefied by the condenser (5) to form high-pressure liquid CO2 and stored in the high-pressure storage tank (6); when the system releases energy, high-pressure liquid CO2 flows out of the high-pressure storage tank (6), is vaporized by the evaporator (7) to form high-pressure gaseous CO2, and then drives the turbine (9) to generate electricity, and is finally stored in the low-pressure gaseous CO2 in the low-pressure gas storage tank (1); Features: The CO2 energy storage unit (18) further includes an interstage cooler (3) and a reheater (11), wherein: The interstage cooler (3) is bidirectionally connected to the compressor (2). The high-temperature and high-pressure gaseous CO2 formed after the compressor (2) compresses the low-pressure gaseous CO2 is cooled in the interstage cooler (3) and then returned to the compressor (2) for recompression. The reheater (11) is bidirectionally connected to the turbine (9). The medium-low temperature gaseous CO2 formed after the high temperature gaseous CO2 performs work on the turbine (9) is heated in the reheater (11) and then returns to the turbine (9) to perform work again.

2. The energy storage system according to claim 1, characterized in that: The CO2 energy storage unit (18) further includes a superheater (8) and a post-stage cooler (4), wherein: The after-stage cooler (4) is arranged between the compressor (2) and the condenser (5) to cool the high-temperature and high-pressure gaseous CO2 generated by the compressor (2); The superheater (8) is arranged between the evaporator (7) and the turbine (9) to heat the low-temperature and high-pressure gaseous CO2 generated by the evaporator (7).

3. The energy storage system according to claim 1 or 2, characterized in that: A regenerator (10) is also provided between the turbine (9) and the low-pressure gas storage tank (1). The medium-low-temperature and low-pressure gaseous CO2 after the turbine (9) has done work is cooled by the regenerator to form low-temperature and low-pressure gaseous CO2 and stored in the low-pressure gas storage tank (1).

4. The energy storage system according to claim 2, characterized in that: The energy storage system further comprises an oil heat storage unit (19), wherein the oil heat storage unit (19) comprises a high-temperature heat-conducting oil tank (12) and a low-temperature heat-conducting oil tank (13), wherein: The outlet of the low-temperature heat transfer oil tank (13) is connected to the heat exchange inlet of the interstage cooler (3) and the heat exchange inlet of the post-stage cooler (4), and the inlet of the high-temperature heat transfer oil tank (12) is connected to the heat exchange outlet of the interstage cooler (3) and the heat exchange outlet of the cooler (4). The low-temperature heat transfer oil in the low-temperature heat transfer oil tank (13) flows to the interstage cooler (3) and the post-stage cooler (4) respectively to absorb the heat of the gaseous CO2 in the interstage cooler (3) and the post-stage cooler (4), and forms high-temperature heat transfer oil to flow to the high-temperature heat transfer oil tank (12); The outlet of the high-temperature heat transfer oil tank (12) is connected to the heat exchange inlet of the superheater (8) and the heat exchange inlet of the reheater (11), and the inlet of the low-temperature heat transfer oil tank (13) is connected to the heat exchange outlet of the superheater (8) and the heat exchange outlet of the reheater (11). The high-temperature heat transfer oil in the high-temperature heat transfer oil tank (12) flows to the reheater (11) and the superheater (8) respectively to heat the gaseous CO2 in the reheater (11) and the superheater (8), and forms low-temperature heat transfer oil which flows to the low-temperature heat transfer oil tank (13).

5. The energy storage system according to claim 3, characterized in that: The energy storage system further comprises a heat pump unit (21), wherein the heat pump unit (21) comprises a compressor (15) and a heat pump condenser (16), wherein the inlet of the compressor (15) is connected to the heat exchange outlet of the condenser (5), and the outlet of the compressor (15) is connected to the heat pump condenser (16), and the heat pump working medium absorbs heat released when the gaseous CO2 is liquefied in the condenser (5) and is heated, and then is compressed into a high-temperature and high-pressure working medium by the compressor (15) and transported to the heat pump condenser (16) for storage.

6. The energy storage system according to claim 5, characterized in that: The outlet of the heat pump condenser (16) is connected to the heat exchange inlet of the condenser (5), and the low-temperature and low-pressure working medium cooled by the heat pump condenser (16) is transported to the condenser (5), wherein a throttle valve (17) is provided on the connection passage between the outlet of the heat pump condenser (16) and the condenser (5).

7. The energy storage system according to claim 5, characterized in that: The energy storage system further comprises a water heat storage unit (20), the water heat storage unit (20) comprising a hot water storage tank (14) bidirectionally connected to the heat pump condenser (16), the low-temperature water outlet of the hot water storage tank (14) being connected to the heat exchange inlet of the heat pump condenser (16), and the heat exchange outlet of the heat pump condenser (16) being connected to the high-temperature water inlet of the hot water storage tank (14); Low-temperature water flows from the hot water storage tank (14) to the heat pump condenser (16), absorbs heat from the high-temperature and high-pressure working medium in the heat pump condenser (16), forms high-temperature water, and returns to the hot water storage tank (14) for storage.

8. The energy storage system according to claim 7, characterized in that: The hot water storage tank (14) is also bidirectionally connected to the evaporator (7); the high-temperature water outlet of the hot water storage tank (14) is connected to the heat exchange inlet of the evaporator (7); the heat exchange outlet of the evaporator (7) is connected to the low-temperature water inlet of the hot water storage tank (14); the high-temperature water flows from the hot water storage tank (14) to the evaporator (7) to provide heat for the vaporization of liquid CO2 in the evaporator (7); and the low-temperature water formed after the evaporator (7) absorbs heat returns to the hot water storage tank (14).

9. The energy storage system according to claim 8, characterized in that: The low-temperature water outlet of the hot water storage tank (14) is also connected to the heat exchange inlet of the regenerator (10) to absorb the heat of the medium- and low-temperature gaseous CO2 in the regenerator (10); the heat exchange outlet of the regenerator (10) is connected to the heat exchange inlet of the evaporator (7) to introduce the formed high-temperature water into the evaporator (7).

10. The energy storage system according to claim 1, characterized in that: The compressor (2) is connected to an electric motor, and the turbine (9) is connected to a generator.

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