Liquid carbon dioxide energy storage refrigerating system

Abstract

The utility model provides a liquid carbon dioxide energy storage refrigerating system. The liquid carbon dioxide energy storage refrigerating system comprises an energy storage system, a refrigerating 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 refrigerating system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, 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 first heat exchanger through a circulation pipeline, and the cold storage tank is coupled with the fourth heat exchanger through a circulation pipeline. In the low peak period of electricity utilization, the electric energy is stored in the form of high-pressure liquid carbon dioxide. And the liquid carbon dioxide is gasified and cooled through pressure reduction of the second throttling pressure reducing valve so as to provide cold energy. And meanwhile, cold energy generated in the refrigeration process can be stored through the heat circulation system and used for cooling carbon dioxide in the energy storage process.

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 refrigeration 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 drawbacks: 1. It is expensive, including the costs of a multi-stage compressor, a multi-stage expander, and atmospheric-pressure carbon dioxide gas storage bags, which contribute significantly to the cost of technology promotion. 2. It also suffers from low energy conversion efficiency. The system converts electrical energy into internal energy via carbon dioxide, stores it, and then releases it as electrical energy, which then generates work. This multiple energy conversions make the system inefficient in scenarios requiring cooling energy. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides a liquid carbon dioxide energy storage refrigeration 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 refrigeration system, characterized by comprising an energy storage system, a refrigeration 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 refrigeration system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, a fourth heat exchanger and a low-pressure liquid storage tank which are hermetically connected in sequence;

[0008] The heat circulation system includes a cold storage tank, which is coupled to the first heat exchanger through a circulation pipe, and the cold storage tank is coupled to the fourth 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 this energy as high-pressure liquid carbon dioxide. The refrigeration system then uses a second throttling valve to reduce pressure, vaporizing the liquid carbon dioxide and cooling it to provide cooling energy. Simultaneously, the thermal cycle system stores the cooling energy generated during the refrigeration process and uses it to cool the carbon dioxide during the energy storage process, 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 evaporative refrigeration system.

[0013] Through the above technical solution, an evaporative refrigeration system is used to refrigerate the high-pressure gaseous carbon dioxide to liquefy it, thereby reducing its volume and making it easier to store.

[0014] Preferably, the third heat exchanger is coupled to an external cooling system.

[0015] Through the above technical solution, cold energy is continuously transmitted to the outside through the external cooling system.

[0016] The pressure of the low-pressure liquid storage tank is 0.8-1.2 MPa, and the pressure of the high-pressure liquid storage tank is 7-9 MPa.

[0017] 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.

[0018] Preferably, the temperature of the low-pressure liquid storage tank is -35°C to 45°C, and the pressure of the high-pressure liquid storage tank is 27-35°C.

[0019] Through the above technical solution, the carbon dioxide in the low-pressure liquid storage tank and the high-pressure liquid storage tank is kept in liquid form, thereby reducing the cost of the carbon dioxide storage equipment.

[0020] Preferably, the pressure of the low-pressure liquid storage tank is 1 MPa, and the pressure of the high-pressure liquid storage tank is 8 MPa.

[0021] Through the above technical solution, the low pressure of 1MPa is adopted to keep the cooling system at a low temperature of -50℃ and continuously provide cold energy to the outside. The high-pressure liquid storage tank adopts 8MPa, which can keep the carbon dioxide in the high-pressure liquid storage tank in liquid state at room temperature.

[0022] Preferably, the temperature of the low-pressure liquid storage tank is -40°C, and the pressure of the high-pressure liquid storage tank is 31°C.

[0023] Through the above technical solution, the carbon dioxide in the low-pressure liquid storage tank and the high-pressure liquid storage tank can be kept in liquid form, thereby reducing the cost of carbon dioxide storage equipment.

[0024] The beneficial effect of this utility model is: abandoning the carbon dioxide energy storage method based on "electricity storage" in the industry market, and developing a carbon dioxide energy storage method based on "cold storage" with higher conversion efficiency. The equipment has the advantages of miniaturization, light weight, low cost and high conversion efficiency. The main methods are as follows:

[0025] Beneficial effects:

[0026] 1. Small and lightweight equipment reduces equipment investment costs. At the low-pressure end of energy storage, the original normal temperature and pressure gaseous carbon dioxide storage method is changed to liquid carbon dioxide as the storage method. While the energy storage density remains unchanged, 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.

[0027] 2. Shifting from a primarily electricity-based energy storage method to a primarily cold storage method improves energy conversion efficiency while also being highly compatible with freeze-drying equipment. This system leverages the ability of carbon dioxide to vaporize at 1 MPa to generate a large amount of -40°C cold energy, which coincides with the large amount of -35°C cold energy required by freeze-drying equipment. This system avoids the inefficient "electricity-electricity-cold" conversion method and directly adopts the highly efficient "electricity-cold" conversion method, significantly improving energy conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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:

[0029] Figure 1 This is a structural diagram of Example 1;

[0030] 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. Fourth heat exchanger, 11. First liquefaction buffer tank, 12. Second liquefaction buffer tank, 13. Cold storage tank. DETAILED DESCRIPTION

[0031] 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.

[0032] 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.

[0033] Example 1

[0034] like Figure 1 A liquid carbon dioxide energy storage refrigeration system is shown, comprising an energy storage system, a refrigeration system and a heat cycle system.

[0035] The energy storage system includes a low-pressure liquid storage tank 1, a first throttling and 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. 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.

[0036] The refrigeration system includes a high-pressure liquid storage tank 6, a second throttling pressure reducing valve 7, a third heat exchanger 8, a fourth heat exchanger 9, and a low-pressure liquid storage tank 1, which are hermetically connected in sequence. A second liquefaction buffer tank 12 is installed between the fourth heat exchanger 9 and the low-pressure liquid storage tank 1 to provide a buffer for the low-pressure carbon dioxide liquefaction process.

[0037] The low-pressure liquid storage tank 1 controls the pressure to 0.8-1.2 MPa, preferably 1 MPa, and the temperature to -35°C--45°C, preferably -40°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.

[0038] The heat circulation system includes a cold storage tank 13 , which is coupled to the first heat exchanger 2 through a circulation pipe. The cold storage tank 13 is coupled to the fourth heat exchanger 9 through a circulation pipe.

[0039] Energy storage process: When electricity prices are low at night, the liquid carbon dioxide with a pressure of 1 MPa and a temperature of -40°C in the low-pressure liquid storage tank 1 is reduced in pressure and gasified through the first throttling pressure reducing valve 2 to form gaseous carbon dioxide with a pressure of 0.8 MPa and a temperature of -45°C. The 0.8 MPa gaseous carbon dioxide passes through the first compressor 4 to form 8 MPa high-pressure gaseous carbon dioxide, and finally passes through the second heat exchanger 5 to liquefy 8 MPa high-pressure liquid carbon dioxide, which is stored in the high-pressure liquid storage tank 6, completing the energy storage process.

[0040] Refrigeration process: The 8Mpa liquid dioxide in the high-pressure liquid storage tank 6 is decompressed and gasified through the second throttling pressure reducing valve 7 to form gaseous carbon dioxide with a pressure of 1Mpa and a temperature of -40°C, which is then passed through the third heat exchanger 8 to provide a large amount of -35°C cold energy required by the freeze-drying equipment.

[0041] Thermal cycle process: During the energy storage process, the -45°C gaseous carbon dioxide that is decompressed and vaporized passes through the first heat exchanger 2 to store the cold energy in the cold storage tank 13, and then the cold energy in the cold storage tank 13 is used to liquefy the gaseous carbon dioxide in the refrigeration process through the first heat exchanger 8.

[0042] 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 refrigeration system, characterized by: Including energy storage system, refrigeration system and heat 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 refrigeration system comprises a high-pressure liquid storage tank, a second throttling pressure reducing valve, a third heat exchanger, a fourth heat exchanger and a low-pressure liquid storage tank which are hermetically connected in sequence; The heat circulation system includes a cold storage tank, which is coupled to the first heat exchanger through a circulation pipe, and the cold storage tank is coupled to the fourth heat exchanger through a circulation pipe.

2. A liquid carbon dioxide energy storage refrigeration 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 refrigeration system according to claim 1, characterized in that: The fourth heat exchanger is connected to the evaporative refrigeration system.

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

5. The liquid carbon dioxide energy storage refrigeration system according to claim 1, characterized in that: The pressure of the low-pressure liquid storage tank is 0.8-1.2 MPa, and the pressure of the high-pressure liquid storage tank is 7-9 MPa.

6. A liquid carbon dioxide energy storage refrigeration system according to claim 1, characterized in that: The temperature of the low-pressure liquid storage tank is -35°C to 45°C, and the pressure of the high-pressure liquid storage tank is 28-34°C.

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

8. The liquid carbon dioxide energy storage refrigeration system according to claim 1, characterized in that: The temperature of the low-pressure liquid storage tank is -40°C, and the pressure of the high-pressure liquid storage tank is 31°C.

Images