Liquid carbon dioxide energy storage system

Abstract

The utility model provides a liquid carbon dioxide energy storage system. The liquid carbon dioxide energy storage system comprises an energy storage system, an energy release system and a heat circulation system, the energy storage system comprises a low-pressure liquid storage tank, a first throttling pressure reducing valve, a first heat exchanger, a compressor, a second heat exchanger and a high-pressure liquid storage tank which are sequentially connected in a sealed mode. The energy releasing system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, a turbo expander, a fourth heat exchanger and a low-pressure liquid storage tank which are sequentially connected in a sealed mode. The heat circulation system comprises a cold storage tank, the cold storage tank is coupled with the second heat exchanger through a circulation pipeline, and the cold storage tank is coupled with the third heat exchanger through a circulation pipeline. And the electric energy can be stored in the form of high-pressure liquid carbon dioxide in the low peak period of electricity utilization. In the peak period of electricity utilization, the energy release system can release energy to generate electricity so as to relieve the electricity utilization pressure. And meanwhile, the heat circulation system can be used for cooling carbon dioxide in the energy storage process, and energy loss is reduced on the whole.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon dioxide energy storage, in particular to a liquid carbon dioxide energy storage system. Background Art

[0002] As a new technology, carbon dioxide energy storage, in existing technical applications, takes advantage of the low electricity price period to convert normal-pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide through a multi-stage compressor, and converts electrical energy into the internal energy of carbon dioxide for storage; during peak electricity consumption periods, the high-pressure liquid carbon dioxide is expanded into normal-pressure gaseous carbon dioxide through a multi-stage expander to generate electricity, ultimately realizing the storage and release of electrical energy.

[0003] However, this system has two disadvantages: 1. The equipment cost is huge. The investment cost of its atmospheric pressure carbon dioxide gas storage bag will be very large, and the cost of technology promotion cannot be ignored; 2. It is difficult to promote. Due to the huge area occupied by its equipment, the project site selection requirements are higher and more difficult. At the same time, its land cost will be very huge. Various conditions will greatly increase the difficulty of promotion. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a liquid carbon dioxide energy storage system, which has the characteristics of being small and lightweight and reducing equipment investment costs.

[0005] The specific scheme is as follows: A liquid carbon dioxide energy storage system is characterized by comprising an energy storage system, an energy release system and a heat circulation system;

[0006] The energy storage system comprises a low-pressure liquid storage tank, a first throttling pressure reducing valve, a first heat exchanger, a compressor, a second heat exchanger and a high-pressure liquid storage tank which are hermetically connected in sequence;

[0007] The energy release system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, a turbine expander, a fourth heat exchanger and a low-pressure liquid storage tank which are sequentially and hermetically connected;

[0008] The heat circulation system includes a cold storage tank, which is coupled to the second heat exchanger through a circulation pipe, and the cold storage tank is coupled to the third heat exchanger through a circulation pipe.

[0009] This technical solution utilizes low-cost electricity during off-peak periods, allowing the energy storage system to store it as high-pressure liquid carbon dioxide. During peak periods, the energy release system can generate electricity to alleviate power pressure. Furthermore, the thermal cycle system can store the cold energy generated during the release process, which can be used to cool the carbon dioxide during storage, thereby reducing overall energy loss.

[0010] Preferably, a first liquefaction buffer tank is installed between the second heat exchanger and the high-pressure liquid storage tank, and a second liquefaction buffer tank is installed between the fourth heat exchanger and the low-pressure liquid storage tank.

[0011] Through the above technical solution, the first liquefaction buffer tank and the second liquefaction buffer tank are used to provide buffering for the carbon dioxide liquefaction process.

[0012] Preferably, the fourth heat exchanger is connected to an R507 cascade system, and the R507 cascade system provides refrigeration.

[0013] Through the above technical solution, low-pressure carbon dioxide can reach a lower temperature and be liquefied for storage.

[0014] Preferably, the R507 cascade system is formed by coupling an R507 refrigeration system and an evaporative cooling refrigeration system.

[0015] The above technical solution makes the structure of the R507 cascade system simpler and reduces the investment cost of the equipment.

[0016] Preferably, the R507 refrigeration system includes an R507 liquid receiver, an R507 pressure reducing valve, an R507 compressor and an R507 condenser connected end to end in sequence, the pipeline between the R507 pressure reducing valve and the R507 compressor is coupled to the fourth heat exchanger, and the R507 condenser is coupled to the evaporative cooling refrigeration system.

[0017] Through the above technical solution, the structure of the R507 refrigeration system is made simpler and easier to install.

[0018] Preferably, the first heat exchanger is coupled to an external cooling system.

[0019] Through the above technical solution, cold energy can be provided to the external cooling system during the energy storage process.

[0020] Preferably, the pressure of the low-pressure liquid storage tank is 2-3 MPa, and the pressure of the high-pressure liquid storage tank is 7-9 MPa.

[0021] Through the above technical solution, the pressure and temperature of the low-pressure liquid storage tank and the high-pressure liquid storage tank are easier to achieve, reducing the construction cost of the overall equipment.

[0022] The pressure of the low-pressure liquid storage tank is 2.5 MPa, and the pressure of the high-pressure liquid storage tank is 8 MPa.

[0023] Through the above technical solution, the construction cost of the overall equipment is further reduced.

[0024] The beneficial effects of the utility model are:

[0025] 1. Small and lightweight equipment reduces equipment investment costs. Liquid carbon dioxide is used at the low-pressure end of the energy storage system. While maintaining the same energy storage density, the storage volume at the low-pressure end is greatly reduced. The equipment can be miniaturized, greatly reducing the difficulty of popularization, reducing equipment investment costs, and increasing the flexibility of production line layout.

[0026] 2. Shifting from primarily electricity storage to a multi-faceted approach that combines electricity and cold storage expands application scenarios. This system utilizes liquid carbon dioxide to vaporize and extract cold energy for use in community air conditioning or cold storage, significantly improving energy conversion efficiency. It also generates electricity during the energy release process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. Among them:

[0028] Figure 1 This is a structural diagram of Example 1;

[0029] 1. Low-pressure liquid storage tank, 2. First throttling pressure reducing valve, 3. First heat exchanger, 4. Compressor, 5. Second heat exchanger, 6. High-pressure liquid storage tank, 7. Second throttling pressure reducing valve, 8. Third heat exchanger, 9. Turbine expander, 10. Fourth heat exchanger, 11. First liquefaction buffer tank, 12. Second liquefaction buffer tank, 13. Cold storage tank, 21. R507 liquid receiver, 22. R507 pressure reducing valve, 23. R507 compressor, 24. R507 condenser. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0032] Example 1

[0033] like Figure 1 A liquid carbon dioxide energy storage system is shown, comprising an energy storage system, an energy release system and a heat cycle system.

[0034] The energy storage system includes a low-pressure liquid storage tank 1, a first throttling and pressure-reducing valve 2, a first heat exchanger 3, a compressor 4, a second heat exchanger 5, and a high-pressure liquid storage tank 6, all tightly connected in sequence. The first heat exchanger 3 is coupled to an external cooling system. A first liquefaction buffer tank 11 is installed between the second heat exchanger 5 and the high-pressure liquid storage tank 6 to provide a buffer for the high-pressure carbon dioxide liquefaction process.

[0035] The energy release system includes a high-pressure liquid storage tank 6, a second throttling pressure reducing valve 7, a third heat exchanger 8, a turbine expander 9, a fourth heat exchanger 10, and a low-pressure liquid storage tank 1, all tightly connected in sequence. A second liquefaction buffer tank 12 is installed between the fourth heat exchanger 10 and the low-pressure liquid storage tank 1 to provide a buffer for the low-pressure carbon dioxide liquefaction process.

[0036] The low-pressure liquid storage tank 1 controls the pressure to 2-3 MPa, preferably 2.5 MPa, and the temperature to -11°C--16°C, preferably -12°C. The high-pressure liquid storage tank 6 controls the pressure to 7-9 MPa, preferably 8 MPa, and the temperature to 27°C-35°C, preferably 31°C.

[0037] The heat circulation system includes a cold storage tank 13 , which is coupled to the second heat exchanger 5 through a circulation pipe. The cold storage tank 13 is coupled to the third heat exchanger 8 through a circulation pipe.

[0038] At night, when electricity prices are low, the 2.5Mpa liquid CO2 in low-pressure liquid storage tank 1 is vaporized by first throttling and reducing valve 2 to form 2.5Mpa gaseous CO2, simultaneously generating a large amount of -12°C cold energy. This cold energy, at approximately -5°C, is captured by first heat exchanger 3 and used for community air conditioning or cold storage. The 2.5Mpa gaseous CO2 passes through first compressor 4 to form 8Mpa high-pressure gaseous CO2. Finally, it is liquefied by second heat exchanger 5 to form 8Mpa high-pressure liquid CO2, which is stored in high-pressure liquid storage tank 6, completing the energy storage and cooling process.

[0039] During daytime periods when electricity prices are high, the 8 MPa liquid CO2 in high-pressure liquid storage tank 6 is vaporized by second throttling and reducing valve 7 to form medium-pressure gaseous CO2 at 5 MPa. This generates a large amount of phase-change cold energy, which is stored in cold storage tank 11. The 5 MPa gaseous CO2 generates electricity through a turbine expansion generator and is simultaneously converted into 2.5 MPa low-pressure gaseous CO2. This is then liquefied through heat exchange in third heat exchanger 8 to form 2.5 MPa liquid CO2, which is then stored in low-pressure liquid storage tank 1, completing the energy release and power supply process.

[0040] In some embodiments, the fourth heat exchanger 10 is connected to an R507 cascade system, which provides cooling. Specifically, the R507 refrigeration system includes an R507 liquid reservoir 21, an R507 pressure reducing valve 22, an R507 compressor 23, and an R507 condenser 24, connected end-to-end. The pipeline between the R507 pressure reducing valve 22 and the R507 compressor 23 is coupled to the fourth heat exchanger 10. The R507 condenser is coupled to the evaporative cooling system.

[0041] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. A liquid carbon dioxide energy storage system, characterized by: Including energy storage system, energy release system and thermal cycle system; The energy storage system comprises a low-pressure liquid storage tank, a first throttling pressure reducing valve, a first heat exchanger, a compressor, a second heat exchanger and a high-pressure liquid storage tank which are hermetically connected in sequence; The energy release system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, a turbine expander, a fourth heat exchanger and a low-pressure liquid storage tank which are sequentially and hermetically connected; The heat circulation system includes a cold storage tank, which is coupled to the second heat exchanger through a circulation pipe, and the cold storage tank is coupled to the third heat exchanger through a circulation pipe.

2. A liquid carbon dioxide energy storage system according to claim 1, characterized in that: A first liquefaction buffer tank is installed between the second heat exchanger and the high-pressure liquid storage tank, and a second liquefaction buffer tank is installed between the fourth heat exchanger and the low-pressure liquid storage tank.

3. The liquid carbon dioxide energy storage system according to claim 1, characterized in that: The fourth heat exchanger is connected to the R507 cascade system, and the R507 cascade system provides refrigeration.

4. A liquid carbon dioxide energy storage system according to claim 3, characterized in that: The R507 cascade system is formed by coupling an R507 refrigeration system and an evaporative cooling refrigeration system.

5. A liquid carbon dioxide energy storage system according to claim 4, characterized in that: The R507 refrigeration system includes an R507 liquid receiver, an R507 pressure reducing valve, an R507 compressor and an R507 condenser connected end to end in sequence, a pipeline between the R507 pressure reducing valve and the R507 compressor is coupled to a fourth heat exchanger, and the R507 condenser is coupled to an evaporative cooling refrigeration system.

6. A liquid carbon dioxide energy storage system according to claim 1, characterized in that: The first heat exchanger is coupled to an external cooling system.

7. The liquid carbon dioxide energy storage system according to claim 1, characterized in that: The pressure of the low-pressure liquid storage tank is 2-3 MPa, and the pressure of the high-pressure liquid storage tank is 7-9 MPa.

8. The liquid carbon dioxide energy storage system according to claim 1, characterized in that: The pressure of the low-pressure liquid storage tank is 2.5 MPa, and the pressure of the high-pressure liquid storage tank is 8 MPa.

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