LNG (Liquefied Natural Gas) cold energy cold storage and cascade cold supply system

Abstract

The utility model relates to the technical field of cold supply, in particular to an LNG cold energy storage and cascade cold supply system which comprises an LNG storage tank, a cryogenic cold exchanger, a shallow cold exchanger and an air temperature type vaporizer, the LNG storage tank is connected with an LNG inlet of the cryogenic cold exchanger, an LNG outlet of the cryogenic cold exchanger is connected with an LNG inlet of the shallow cold exchanger, and the air temperature type vaporizer is connected with the cryogenic cold exchanger. An LNG outlet of the shallow cooling cold exchanger is connected with an inlet of the air temperature type vaporizer, and an outlet of the air temperature type vaporizer is connected with a natural gas pipe network. The LNG peak regulation system has excellent LNG peak regulation performance, when the LNG demand quantity rises, a large amount of cold energy released by LNG gasification can be absorbed through solidification of the phase change materials in the cold storage tank, and the LNG gasification efficiency and stability are guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of cooling technology, and in particular to an LNG cold energy storage and cascade cooling system. Background Technology

[0002] Liquefied natural gas (LNG), as a green and efficient energy source, releases a significant amount of cold energy during its gasification process. Recovering and utilizing this cold energy is beneficial for energy conservation, improving overall energy efficiency, and reducing electricity consumption and carbon emissions. Existing technologies for recovering and utilizing LNG cold energy to supply cooling systems downstream only consider the scenario of continuous LNG supply and continuous downstream cooling, neglecting the problem of mismatch between upstream LNG cooling supply and downstream commercial complex cooling needs. For upstream LNG receiving terminals, the LNG gasification process, once completed, enters the natural gas pipeline network, requiring a stable and continuous LNG gasification rate. However, for downstream cooling systems such as commercial complexes, their cooling demands are constantly changing. For example, the cooling load of cryogenic freeze-drying, cold storage, and centralized industrial park cooling systems fluctuates continuously throughout the day due to various factors such as season, pedestrian traffic, and diurnal variations. Furthermore, the temperature requirements for different application scenarios also differ; for instance, cold storage requires deep cooling, while air conditioning systems require shallow cooling. Therefore, when applying LNG cooling energy to various commercial complexes (air conditioning, cold storage, etc.), while ensuring a continuous supply of LNG and continuous cooling downstream, it is also necessary to solve the problem of matching the upstream LNG supply with the downstream cooling temperature. Utility Model Content

[0003] The purpose of this utility model is to solve the technical problems mentioned in the background section.

[0004] The present invention adopts the following technical solution: an LNG cold energy storage and cascade cooling system, including an LNG storage tank, a cryogenic cooler, a shallow cooler, and an ambient air vaporizer. The LNG storage tank is connected to the LNG inlet of the cryogenic cooler, the LNG outlet of the cryogenic cooler is connected to the LNG inlet of the shallow cooler, the LNG outlet of the shallow cooler is connected to the inlet of the ambient air vaporizer, and the outlet of the ambient air vaporizer is connected to the natural gas pipeline network.

[0005] Preferably, at the cryogenic LNG exchange end, the system includes: a cryogenic cold storage tank, circulating pump one, circulating pump two, a cryogenic user-end cold exchanger, circulating pump three, valve one, valve two, and a cryogenic refrigeration unit. At the shallow LNG exchange end, the device includes: a shallow cold storage tank, circulating pump four, circulating pump five, a shallow cold user-end cold exchanger, circulating pump six, valve three, valve four, and a shallow refrigeration unit. The shallow cold storage tank has a double-coil structure.

[0006] Preferably, the cryogenic cold storage tank and the shallow cold storage tank have a dual-coil structure, with the coil direction ab being the channel for the refrigerant of the LNG end cooler and the coil direction cd being the channel for the refrigerant of the user end cooler. The tank is filled with phase change cold storage material.

[0007] Preferably, the refrigerant outlet of the cryogenic cooler is connected to the refrigerant inlet a of the cryogenic cold storage tank, the refrigerant outlet b of the cryogenic cold storage tank is connected to the inlet of the first circulating pump, and the outlet of the first circulating pump is connected to the refrigerant inlet of the cryogenic cooler.

[0008] Preferably, at the user's cooling end, the refrigerant outlet d of the cryogenic cold storage tank is connected to the second circulating pump, the outlet of the second circulating pump is connected to the refrigerant inlet of the cryogenic user-end cooling exchanger, and the refrigerant outlet of the cryogenic user-end cooling exchanger is connected to the refrigerant inlet c of the cryogenic cold storage tank.

[0009] Preferably, the refrigerant outlet b of the shallow cold storage tank is connected to the inlet of the fourth circulating pump, and the outlet of the fourth circulating pump is connected to the refrigerant inlet of the shallow cold exchanger.

[0010] Preferably, at the user's cooling end, the refrigerant outlet d of the shallow cold storage tank is connected to the circulating pump five, the outlet of the circulating pump five is connected to the refrigerant inlet of the shallow cold user-end cooling exchanger, and the refrigerant outlet of the shallow cold user-end cooling exchanger is connected to the refrigerant inlet c of the shallow cold storage tank.

[0011] Ideally, at the user end of the cold energy system, valve two is installed in parallel with the shallow-cooling refrigeration unit, and valve four is installed in parallel with the deep-cooling refrigeration unit.

[0012] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0013] 1. This utility model has excellent LNG peak-shaving performance: when the demand for LNG increases, the solidification of the phase change material in the cold storage tank can absorb a large amount of cold energy released by LNG gasification, ensuring the efficiency and stability of LNG gasification.

[0014] 2. This utility model provides stable cooling: when the phase change cold storage material melts, it releases a large amount of cold energy, but the temperature remains almost unchanged. This characteristic enables the phase change cold storage material to provide a more stable low-temperature environment. When the LNG cold energy is insufficient, the electric cooling system is activated to ensure an uninterrupted supply of cold energy and reduce temperature fluctuations at the user end.

[0015] 3. This utility model enables highly efficient cascaded utilization of cold energy: by recovering LNG cold energy through a multi-stage cooling system, the cold energy released during LNG vaporization can be extracted and recovered to the maximum extent, thereby improving the efficiency of cold energy resource recovery and utilization.

[0016] 4. This utility model provides an LNG cold energy storage and cascade cooling system that can effectively utilize the large amount of cold energy released during LNG vaporization. The generated cold energy can be used in various commercial complexes, such as low-temperature freeze drying, cold storage, and air conditioning. According to the changing cooling needs of downstream commercial complexes, the system achieves periodic alternation between the cold storage and cooling modes through the coordinated operation of the cold storage loop and electric refrigeration in the energy conversion system. This ensures cooling for downstream applications while reducing fluctuations in LNG supply and maintaining the stable and continuous vaporization of upstream LNG. This results in a good match between the upstream LNG cooling system and the downstream cooling system, improving the overall utilization rate of LNG cold energy and reducing the cooling energy consumption of the downstream cooling system, thus achieving significant energy saving and emission reduction effects. Attached Figure Description

[0017] Figure 1 This utility model provides a schematic diagram of an LNG cold energy storage and cascade cooling system.

[0018] Figure 2 This utility model presents a schematic diagram of an LNG storage tank for an LNG cold energy storage and cascade cooling system.

[0019] Legend:

[0020] 1. LNG storage tank; 2. Cryogenic cooler; 3. Shallow cooler; 4. Ambient air vaporizer; 5. Cryogenic cold storage tank; 6. Circulation pump one; 7. Circulation pump two; 8. Cryogenic user-end cooler; 9. Circulation pump three; 10. Valve one; 11. Valve two; 12. Cryogenic refrigeration unit; 13. Shallow cooler cold storage tank; 14. Circulation pump four; 15. Circulation pump five; 16. Shallow cooler user-end cooler; 17. Circulation pump six; 18. Valve three; 19. Valve four; 20. Shallow cooler refrigeration unit. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed in the following specification.

[0023] Example

[0024] In the vaporization loop, LNG storage tank 1 is connected to the LNG inlet of cryogenic cooler 2, the LNG outlet of cryogenic cooler 2 is connected to the LNG inlet of shallow cooler 3, the LNG outlet of shallow cooler 3 is connected to the inlet of ambient air vaporizer 4, and the outlet of ambient air vaporizer 4 is connected to the natural gas pipeline network. Methanol is used as the refrigerant in the cryogenic end, and ethylene glycol solution is used as the refrigerant in the shallow cooler end. LNG flows out of storage tank 1 and enters LNG cryogenic cooler 2 through pipelines. LNG at -65℃ is cooled by methanol. The LNG is heated to -65 to -60℃ for initial vaporization and cooling, while the methanol is cooled to -55℃. The cooled natural gas then enters the LNG shallow cooling exchanger 3 and exchanges cooling with ethylene glycol solution. The LNG is heated to -30 to -25℃ for complete vaporization and cooling, while the ethylene glycol solution is cooled to -20℃. The natural gas then enters the ambient temperature vaporizer 4 and is heated to room temperature before being supplied to downstream users. The pressure of methanol and ethylene glycol solution in the cooling cycle is 0.3 MPa.

[0025] At the LNG cryogenic cooling end, the device includes: a cryogenic cold storage tank 5, a circulating pump 1 6, a circulating pump 2 7, a cryogenic user-end cooler 8, a circulating pump 3 9, a valve 10, a valve 2 11, and a cryogenic refrigeration unit 12. The cryogenic cold storage tank 5 has a double-coil structure. The coil direction ab is the channel for the refrigerant in the LNG-end cooler, and the coil cd is the channel for the refrigerant in the user-end cooler. The tank is filled with a phase change cold storage material with a freezing point of -50℃. In the first refrigerant cycle, the refrigerant outlet of the cryogenic cooler 2 is connected to the refrigerant inlet a of the cryogenic cold storage tank 5, and the refrigerant outlet b of the cryogenic cold storage tank 5 is connected to the refrigerant outlet b of the cryogenic cold storage tank 5. The refrigerant outlet of the cryogenic storage tank 5 is connected to the refrigerant inlet of the cryogenic user-end refrigerant exchanger 2, and the outlet of the cryogenic storage tank 5 is connected to the refrigerant outlet d of the cryogenic storage tank 5. The outlet of the cryogenic storage tank 5 is connected to the refrigerant inlet of the cryogenic user-end refrigerant exchanger 8, and the outlet of the cryogenic user-end refrigerant exchanger 8 is connected to the refrigerant inlet c of the cryogenic storage tank 5. In the third refrigerant cycle, after the refrigerant is cooled by the cryogenic user-end refrigerant exchanger 8, it enters the third circulating pump 9 for use by the cryogenic user. After the refrigerant is heated, it returns to the cryogenic user-end refrigerant exchanger 8, completing the cryogenic cooling cycle.

[0026] In the first refrigerant cycle, the cooled methanol flows out of the cryogenic heat exchanger 2 and enters the cryogenic cold storage tank 5 under the action of the circulating pump 6. It flows through the tube side ab and exchanges heat with the phase change energy storage material in the cryogenic cold storage tank 5, transferring the cold energy of LNG to the phase change energy storage material. The phase change energy storage material is cooled to -50°C. If the LNG cold energy is sufficient, the phase change energy storage material solidifies or partially solidifies for cold storage. If the LNG cold energy is insufficient, the phase change energy storage material only cools down without solidifying. In the second refrigerant cycle, methanol flows through the tube side cd and exchanges heat with the phase change energy storage material in the cryogenic cold storage tank 5. The cooled methanol then enters the cryogenic user-end heat exchanger 8 through the circulating pump 7 for another heat exchange. In the third refrigerant cycle, methanol flows through the cryogenic user-end heat exchanger 8 and exchanges heat with the methanol in the second cycle. Under the action of the circulating pump 9, the cooled methanol provides cold energy to the user.

[0027] At the LNG shallow cooling exchange end, the device includes: a shallow cooling storage tank 13, a fourth circulation pump 14, a fifth circulation pump 15, a shallow cooling user-end cooler 16, a circulation pump 17, a third valve 18, a fourth valve 19, and a shallow cooling refrigeration unit 20. The shallow cooling storage tank 13 has a double-coil structure. The coil direction ab is the channel for the refrigerant in the LNG-end cooler, and the coil cd is the channel for the refrigerant in the user-end cooler. The tank is filled with a phase change cold storage material with a freezing point of -20℃. In the fourth refrigerant cycle, the refrigerant outlet of the shallow cooling exchanger 3 is connected to the refrigerant inlet a of the shallow cooling storage tank 13, and the refrigerant outlet b of the shallow cooling storage tank 13 is connected to... The inlet of circulating pump 4 14 is connected to the refrigerant inlet of shallow cold exchanger 3; in the fifth refrigerant cycle, the refrigerant outlet d of shallow cold storage tank 13 is connected to circulating pump 5 15, the outlet of circulating pump 5 15 is connected to the refrigerant inlet of shallow cold user-end exchanger 16, and the refrigerant outlet of shallow cold user-end exchanger 16 is connected to the refrigerant inlet c of shallow cold storage tank 13; in the sixth refrigerant cycle, after the refrigerant is cooled by the shallow cold user-end exchanger 16, it enters circulating pump 17 for use by shallow cold users. After the refrigerant is heated, it returns to the shallow cold user-end exchanger 16, completing the shallow cold cooling cycle.

[0028] In the fourth refrigerant cycle, the cooled methanol flows out of the shallow cold exchanger 3 and enters the shallow cold storage tank 13 under the action of the circulation pump 14. It flows through the tube side ab and exchanges cold with the phase change storage material in the shallow cold storage tank 13, transferring the cold energy of LNG to the phase change storage material. The phase change storage material is cooled to -20℃. If the LNG cold energy is sufficient, the phase change storage material solidifies or partially solidifies for cold storage. If the LNG cold energy is insufficient, the phase change storage material only cools down without solidifying. In the second refrigerant cycle, methanol flows through the tube side cd and exchanges cold with the phase change storage material in the shallow cold storage tank 13. The cooled methanol enters the shallow cold user-end cold exchanger 16 through the circulation pump 15 for further cold exchange. In the third refrigerant cycle, methanol flows through the shallow cold user-end cold exchanger 16 and exchanges cold with the methanol in the second cycle. Under the action of the circulation pump 17, the cooled methanol provides cold energy to the user.

[0029] In the third and sixth refrigerant cycles, valve 2 11 is installed in parallel with the shallow-cooled refrigeration unit 12, and valve 4 19 is installed in parallel with the deep-cooled refrigeration unit 20. When the LNG cooling energy is insufficient, valve 2 11 and valve 4 19 are closed, valve 1 10 and valve 3 18 are opened, the electric refrigeration unit is started, the refrigerant flows through the electric refrigeration unit, and after being cooled by the refrigeration unit, it is then supplied to the user for cooling.

[0030] This embodiment introduces two application methods for low-temperature zones. The actual temperature zone and phase change cold storage materials for different temperatures can be selected and adjusted according to user needs. The two-stage cooling described above is only for illustration and is not limited to two stages in practice; it can be further divided into multi-stage cooling. The refrigerant used in this embodiment is a methanol and ethylene glycol solution, but it is not limited to these two materials and can be adjusted as needed. It should be noted that although several structures of LNG-based cold energy supply and cold storage systems have been mentioned in the detailed description above, this division is not mandatory. The characteristics and functions of one structure described above can be further specified by multiple structures.

[0031] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the technical solution of the present utility model.

Claims

1. An LNG cold energy storage and cascade cooling system, comprising an LNG storage tank (1), a cryogenic cooler (2), a shallow cooler (3), and an ambient temperature vaporizer (4), characterized in that: The LNG storage tank (1) is connected to the LNG inlet of the cryogenic cooler (2), the LNG outlet of the cryogenic cooler (2) is connected to the LNG inlet of the shallow cooler (3), the LNG outlet of the shallow cooler (3) is connected to the inlet of the ambient air vaporizer (4), and the outlet of the ambient air vaporizer (4) is connected to the natural gas pipeline network.

2. The LNG cold energy storage and cascade cooling system according to claim 1, characterized in that: At the cryogenic LNG exchange end, the system includes: a cryogenic cold storage tank (5), a circulating pump one (6), a circulating pump two (7), a cryogenic user-end cold exchanger (8), a circulating pump three (9), a valve one (10), a valve two (11), and a cryogenic refrigeration unit (12). At the shallow LNG exchange end, the system includes: a shallow cold storage tank (13), a circulating pump four (14), a circulating pump five (15), a shallow cold user-end cold exchanger (16), a circulating pump six (17), a valve three (18), a valve four (19), and a shallow refrigeration unit (20). The shallow cold storage tank (13) has a double-coil structure.

3. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: The cryogenic cold storage tank (5) and the shallow cold storage tank (13) are a double-coil structure. The coil direction ab is the channel for the refrigerant of the LNG end cooler, and the coil direction cd is the channel for the refrigerant of the user end cooler. The tank is filled with phase change cold storage material.

4. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: The refrigerant outlet of the cryogenic cooler (2) is connected to the refrigerant inlet a of the cryogenic cold storage tank (5), the refrigerant outlet b of the cryogenic cold storage tank (5) is connected to the inlet of the circulating pump (6), and the outlet of the circulating pump (6) is connected to the refrigerant inlet of the cryogenic cooler (2).

5. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: At the user's cooling end, the refrigerant outlet d of the cryogenic storage tank (5) is connected to the second circulating pump (7), the outlet of the second circulating pump (7) is connected to the refrigerant inlet of the cryogenic user-end cooler (8), and the refrigerant outlet of the cryogenic user-end cooler (8) is connected to the refrigerant inlet c of the cryogenic storage tank (5).

6. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: The refrigerant outlet b of the shallow cold storage tank (13) is connected to the inlet of the circulating pump four (14), and the outlet of the circulating pump four (14) is connected to the refrigerant inlet of the shallow cold exchanger (3).

7. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: At the user's cooling end, the refrigerant outlet d of the shallow cold storage tank (13) is connected to the circulating pump five (15), the outlet of the circulating pump five (15) is connected to the refrigerant inlet of the shallow cold user end cooler (16), and the refrigerant outlet of the shallow cold user end cooler (16) is connected to the refrigerant inlet c of the shallow cold storage tank (13).

8. The LNG cold energy storage and cascade cooling system according to claim 2, characterized in that: At the cold energy user end, valve 2 (11) is installed in parallel with the cryogenic refrigeration unit (12), and valve 4 (19) is installed in parallel with the cryogenic refrigeration unit (12).

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