An LNG cascade cold energy utilization system and method

Abstract

The present invention discloses an LNG cascade cold energy utilization system, which includes an LNG fuel storage tank, an LNG vaporizer, a first heat exchanger and a second heat exchanger. The self-booster is communicated with the inlet of the internal coil of the first air-cooled machine, and the outlet of the internal coil of the first air-cooled machine is communicated with the LNG vaporizer; the LNG fuel storage tank is communicated with the LNG vaporizer, and the outlet of the LNG vaporizer is communicated with the second air-cooled machine; the LNG vaporizer is communicated with the inlet of the cold source channel of the first heat exchanger, and the outlet of the cold source channel of the first heat exchanger is communicated with the inlet of the cold source channel of the second heat exchanger; the heat source channel of the first heat exchanger is communicated with the outlet of the refrigerant storage tank. The present invention also provides an LNG cascade cold energy utilization method. The beneficial effects of the present invention are as follows: By designing multiple-stage air-cooled machines and heat exchangers, and utilizing the heat absorption during the LNG vaporization process to provide cooling capacity for the cold storage, machine room and office area, this cascade design realizes the temperature regulation requirements of each area and greatly improves the utilization rate of LNG cold energy.

Description

Technical Field

[0001] The present invention relates to the technology of LNG cold energy utilization, and particularly to an LNG cascade cold energy utilization system and method. Background Art

[0002] LNG (Liquefied Natural Gas) is a clean and efficient energy source, with advantages such as flexible and economical transportation, high storage efficiency, facilitating the regulation of urban gas load, and its safety performance and economic benefits are higher than those of gasoline, diesel, and CNG. It has broad application prospects in power generation, civil fuel, industrial furnaces, automobiles, and shipping.

[0003] Using the principle that the cold energy of LNG vaporization absorbs heat to cool the surrounding medium for refrigeration of cold storage and chilled water is an important part of LNG cold energy utilization, and its utilization methods are diverse and widely applied. As one of the commonly used energy sources, LNG can utilize the heat absorption capacity during its vaporization process by combining heat exchange equipment. However, the existing LNG cold energy utilization technologies are mostly single-stage utilization systems, which have problems such as low efficiency, low cold energy utilization rate, large initial investment, and unstable system operation. Summary of the Invention

[0004] The purpose of the present invention is to provide an LNG cascade cold energy utilization system and method with high cold energy utilization rate in view of the deficiencies of the prior art.

[0005] The technical solution adopted by the present invention is: an LNG cascade cold energy utilization system, including an LNG fuel storage tank, an LNG vaporizer, a first heat exchanger, and a second heat exchanger. A self-booster is provided on one side of the LNG fuel storage tank, and the inlet and outlet of the self-booster are respectively connected to the LNG fuel storage tank through pipelines; the outlet of the self-booster is connected to the inlet of the internal coil of the first air-cooled machine through a first pipeline, and the outlet of the internal coil of the first air-cooled machine is connected to the LNG vaporizer through a second pipeline and a return pipeline; the outlet of the LNG fuel storage tank is connected to the inlet of the LNG vaporizer through a third pipeline, and the outlet of the LNG vaporizer is connected to the inlet of the internal coil of the second air-cooled machine through a fourth pipeline, and the outlet of the internal coil of the second air-cooled machine is connected to the return pipeline through a fifth pipeline; the outlet of the LNG vaporizer is connected to the inlet of the cold source channel of the first heat exchanger through a sixth pipeline, and the outlet of the cold source channel of the first heat exchanger is connected to the inlet of the cold source channel of the second heat exchanger through a seventh pipeline; the heat source channel of the first heat exchanger is connected to the outlet of the refrigerant storage tank, the outlet of the heat source channel of the first heat exchanger is connected to the inlet of the internal coil of the third air-cooled machine, and the outlet of the cold source channel of the second heat exchanger is connected to the subsequent LNG treatment system through an eighth pipeline; valves are respectively provided on each pipeline.

[0006] According to the above solution, the outlet of the internal coil of the third air cooler is connected to the inlet of the internal coil of the fourth air cooler through the eighth pipeline and the ninth pipeline in sequence, and the outlet of the internal coil of the fourth air cooler is connected to the inlet of the refrigerant storage tank.

[0007] According to the above solution, the first air cooler and the second air cooler are installed in the cold storage, and the temperature of the cold storage is controlled below -22°C; the third air cooler is installed in the machine room, and the temperature of the machine room is controlled at 15°C to 20°C; the fourth air cooler is installed in the office area, and the temperature of the office area is controlled at 25°C to 28°C.

[0008] According to the above solution, the refrigerant medium is R22, R410A or R32 working fluid.

[0009] According to the above solution, the inlet of the heat source channel of the second heat exchanger is connected to the equipment cooling water inlet pipeline, and the outlet of the refrigerant channel of the second heat exchanger is connected to the equipment cooling water outlet pipeline.

[0010] According to the above solution, the cold source and the heat source in the second heat exchanger flow in reverse.

[0011] According to the above solution, the first pipeline connected to the inlet of the internal coil of the first air cooler, the second pipeline connected to the outlet of the internal coil of the first air cooler, the fifth pipeline connected to the outlet of the internal coil of the second air cooler, the eighth pipeline connected to the outlet of the internal coil of the third air cooler, and the ninth pipeline connected to the inlet of the internal coil of the fourth air cooler are respectively provided with pressure regulating valves.

[0012] According to the above solution, the third pipeline connecting the LNG fuel storage tank and the LNG vaporizer, the sixth pipeline connecting the LNG vaporizer and the first heat exchanger, and the seventh pipeline connecting the first heat exchanger and the second heat exchanger are respectively provided with pressure regulating valves and temperature transmitters.

[0013] The present invention also provides an LNG cascade cold energy utilization method based on the above system. The method is as follows: The LNG in the LNG fuel storage tank flows into the first air cooler through the self-booster, the LNG in the LNG fuel storage tank enters the LNG vaporizer, the LNG of the LNG vaporizer flows into the second air cooler to provide cold energy for the cold storage, so that the temperature of the cold storage is controlled below -22°C; the LNG flowing out of the LNG vaporizer enters the first heat exchanger to exchange heat with the refrigerant fluid, and the refrigerant fluid enters the third air cooler to provide cold energy for the machine room, so that the temperature of the machine room is 15°C to 20°C; after the refrigerant fluid flows out of the third air cooler, it enters the fourth air cooler to provide cold energy for the office area, so that the temperature of the office area is 25°C to 28°C.

[0014] The beneficial effects of the present invention are as follows: The present invention designs a multi-stage air cooler and a heat exchanger, which utilize the heat absorption during the LNG vaporization process to provide cooling for the cold storage, machine room, and office area. The cold demand of the cold storage, machine room, and office area decreases in sequence. This cascaded design realizes the temperature adjustment requirements of each area and greatly improves the utilization rate of LNG cold energy. The present invention designs a regulating valve on the corresponding pipeline, effectively utilizes the heat absorption capacity of LNG under different pressures, realizes temperature matching, and does not consume any energy during the process. A supercharger is designed to effectively cope with the pressure reduction during the release process of the fuel storage tank and maintain the pressure of the storage tank, so that the system operates stably. Brief Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a specific embodiment of the present invention.

[0016] In the figure: 1 - LNG fuel storage tank, 2 - LNG vaporizer, 3 - First heat exchanger, 4 - Refrigerant storage tank, 5 - First air cooler, 6 - Second air cooler, 7 - Third air cooler, 8 - Fourth air cooler, 9 - Self-supercharger, 10 - Pressure regulating valve, 11 - Temperature transmitter, 12 - First pipeline, 13 - Second pipeline, 14 - Third pipeline, 15 - Fourth pipeline, 16 - Fifth pipeline, 17 - Sixth pipeline, 18 - Second heat exchanger, 19 - Cold storage, 20 - Machine room, 21 - Office area, 22 - Seventh pipeline, 23 - Valve, 24 - Eighth pipeline, 25 - Ninth pipeline. Detailed Embodiment

[0017] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In the following paragraphs, the present invention will be described more specifically by way of example with reference to the accompanying drawings. The advantages and features of the present invention will be clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise scales, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0018] Such as Figure 1An LNG cascade cold energy utilization system shown in the figure includes an LNG fuel storage tank 1, an LNG vaporizer 2, a first heat exchanger 3 and a second heat exchanger 18. A self-booster 9 is provided on one side of the LNG fuel storage tank 1. The inlet and outlet of the self-booster 9 are respectively connected to the LNG fuel storage tank 1 through pipelines. The outlet of the self-booster 9 is connected to the inlet of the internal coil of the first air cooler 5 through a first pipeline 12. The outlet of the internal coil of the first air cooler 5 is connected to the LNG vaporizer 2 through a second pipeline 13 and a return pipeline. The outlet of the LNG fuel storage tank 1 is connected to the inlet of the LNG vaporizer 2 through a third pipeline 14. The outlet of the LNG vaporizer 2 is connected to the inlet of the internal coil of the second air cooler 6 through a fourth pipeline 15. The outlet of the internal coil of the second air cooler 6 is connected to the return pipeline through a fifth pipeline 16. The outlet of the LNG vaporizer 2 is connected to the inlet of the cold source channel of the first heat exchanger 3 through a sixth pipeline 17. The outlet of the cold source channel of the first heat exchanger 3 is connected to the inlet of the cold source channel of the second heat exchanger 18 through a seventh pipeline 22. The heat source channel of the first heat exchanger 3 is connected to the outlet of the refrigerant storage tank 4. The outlet of the heat source channel of the first heat exchanger 3 is connected to the inlet of the internal coil of the third air cooler 7. The outlet of the cold source channel of the second heat exchanger 18 is connected to the subsequent LNG treatment system through an eighth pipeline 24. Valves 23 are respectively provided on each pipeline.

[0019] Preferably, the outlet of the internal coil of the third air cooler 7 is sequentially connected to the inlet of the internal coil of the fourth air cooler 8 through an eighth pipeline 24 and a ninth pipeline 25. The outlet of the internal coil of the fourth air cooler 8 is connected to the inlet of the refrigerant storage tank 4.

[0020] Preferably, the refrigerant medium is R22, R410A or R32 working fluid.

[0021] Preferably, the inlet of the heat source channel of the second heat exchanger 18 is connected to the equipment cooling water inlet pipeline, and the outlet of the refrigerant channel of the second heat exchanger 18 is connected to the equipment cooling water outlet pipeline. In this embodiment, the cold source and the heat source in the second heat exchanger 18 flow reversely. The cooling water is for heat exchange of the pump.

[0022] Preferably, the first air cooler 5 and the second air cooler 6 are installed in a cold storage 19, and the temperature of the cold storage 19 is controlled below -22 °C.

[0023] Preferably, the third air cooler 7 is installed in a machine room 20, and the temperature of the machine room 20 is controlled at 15 °C to 20 °C.

[0024] Preferably, the fourth air cooler 8 is installed in an office area 21, and the temperature of the office area 21 is controlled at 25 °C to 28 °C.

[0025] Preferably, pressure regulating valves 10 are respectively provided on the first pipeline 12 communicating with the inlet of the internal coil of the first air cooler 5, the second pipeline 13 communicating with the outlet of the internal coil of the first air cooler 5, the fifth pipeline 16 communicating with the outlet of the internal coil of the second air cooler 6, the eighth pipeline 24 communicating with the outlet of the internal coil of the third air cooler 7, and the ninth pipeline 25 communicating with the inlet of the internal coil of the fourth air cooler 8.

[0026] Preferably, pressure regulating valves 10 and temperature transmitters 11 are respectively provided on the third pipeline 14 connecting the LNG fuel storage tank 11 and the LNG vaporizer 2, the sixth pipeline 17 connecting the LNG vaporizer 2 and the first heat exchanger 3, and the seventh pipeline 22 connecting the first heat exchanger 3 and the second heat exchanger 18.

[0027] In this embodiment, the tier of the LNG fuel storage tank 1 is 85 m 3 , the design pressure is 1.2 MPa, and the design temperature is -196°C. The pressure of the fluid in the third pipeline 14 connecting the LNG fuel storage tank 1 and the LNG vaporizer 2 is 0.8 - 0.9 MPa, and the temperature is -169°C; the pressure of the fluid in the sixth pipeline 17 connecting the LNG vaporizer 2 and the first heat exchanger 3 is 0.8 - 0.9 MPa, and the temperature is -126.45°C.

[0028] An LNG cascade cold energy utilization method based on the above - mentioned system is as follows: The LNG in the LNG fuel storage tank 1 flows into the first air cooler 5 through the self - booster 9. The LNG in the LNG fuel storage tank 1 enters the LNG vaporizer 2. The LNG of the LNG vaporizer 2 flows into the second air cooler 6 to provide cold energy for the cold storage 19, so that the temperature of the cold storage 19 is controlled below -22°C. The LNG flowing out of the LNG vaporizer 2 enters the first heat exchanger 3 to exchange heat with the refrigerant fluid. The refrigerant fluid enters the third air cooler 7 to provide cold energy for the machine room 20, so that the temperature of the machine room 20 is 15°C - 20°C. After flowing out of the third air cooler 7, the refrigerant fluid enters the fourth air cooler 8 to provide cold energy for the office area 21, so that the temperature of the office area 21 is 25°C - 28°C.

[0029] Specifically, the LNG in the LNG fuel storage tank 1 is pressurized by the self-booster 9 and enters the first air cooler 5 to provide cooling capacity for the cold storage 19. The pressure regulating valve 10 and the valve 23 on the first pipeline 12 are adjusted to regulate the LNG on this pipeline, so that the temperature of the cold storage 19 is lower than -22°C; the LNG in the LNG fuel storage tank 1 enters the LNG vaporizer 2 for vaporization, and the LNG of the LNG vaporizer 2 flows into the second air cooler 6 through the pipeline; the LNG in the cold storage 19 converges and then flows back to the LNG vaporizer 2 through the return pipeline. The LNG in the LNG vaporizer 2 flows into the first heat exchanger 3 through the sixth pipeline 17 and exchanges heat with the refrigerant fluid; after heat exchange, the refrigerant fluid in the first heat exchanger 3 enters the third air cooler 7 to provide cooling capacity for the machine room 20, so that the temperature of the machine room 20 is controlled at 15°C; the refrigerant fluid flows out of the third air cooler 7 and then enters the fourth air cooler 8 to provide cooling capacity for the office area 21, so that the controlled temperature of the office area 21 is 25°C; the refrigerant fluid flows out of the fourth air cooler 8 and then flows back to the refrigerant storage tank 4; after the LNG flows exchange heat in the first heat exchanger 3, it flows into the second heat exchanger 18 through the seventh pipeline 22 and exchanges heat with the refrigerant fluid in the second heat exchanger 18 to provide cooling capacity for the cooling of other equipment.

[0030] In the present invention, the cooling capacity matching of each area is realized by adjusting the opening degrees of the respective valves 23. The temperature of the cold storage 19 is controlled below -22°C, the temperature of the machine room 20 is set at 15°C, and the office area 21 is set at 25°C. The temperatures of the cold storage 19, the machine room 20, and the office area 21 are distributed in a stepped manner. Specifically, the first air cooler 5 and the second air cooler 6 in the cold storage 19 are respectively pressure-regulated by the corresponding pressure regulating valve 10 and the valve 23 to achieve cooling capacity matching; the third air cooler 7 and the fourth air cooler 8 in the machine room 20 and the office area 21 are regulated by the pressure regulating valve 10 on the sixth pipeline 17 to achieve the cooling capacity matching of the first heat exchanger 3.

[0031] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention; any ordinary technical personnel in this industry can smoothly implement the present invention according to the instructions shown in the attached drawings and the above description; however, any minor changes, modifications, and equivalent variations made by those skilled in the art within the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications, and variations made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An LNG cascade cold energy utilization system, characterized in that, It includes an LNG fuel storage tank, an LNG vaporizer, a first heat exchanger and a second heat exchanger. A self-booster is provided on one side of the LNG fuel storage tank. The inlet and outlet of the self-booster are respectively connected to the LNG fuel storage tank through pipelines; the outlet of the self-booster is connected to the inlet of the internal coil of the first air cooler through a first pipeline, and the outlet of the internal coil of the first air cooler is connected to the LNG vaporizer through a second pipeline and a reflux pipeline; the outlet of the LNG fuel storage tank is connected to the inlet of the LNG vaporizer through a third pipeline, the outlet of the LNG vaporizer is connected to the inlet of the internal coil of the second air cooler through a fourth pipeline, and the outlet of the internal coil of the second air cooler is connected to the reflux pipeline through a fifth pipeline; the outlet of the LNG vaporizer is connected to the inlet of the cold source channel of the first heat exchanger through a sixth pipeline, and the outlet of the cold source channel of the first heat exchanger is connected to the inlet of the cold source channel of the second heat exchanger through a seventh pipeline; the heat source channel of the first heat exchanger is connected to the outlet of the refrigerant storage tank, the outlet of the heat source channel of the first heat exchanger is connected to the inlet of the internal coil of the third air cooler, and the outlet of the cold source channel of the second heat exchanger is connected to the subsequent LNG treatment system through an eighth pipeline; valves are respectively provided on each pipeline; The outlet of the internal coil of the third air cooler is successively connected to the inlet of the internal coil of the fourth air cooler through an eighth pipeline and a ninth pipeline; the outlet of the internal coil of the fourth air cooler is connected to the inlet of the refrigerant storage tank.

2. The LNG cascade cold energy utilization system according to claim 1, characterized in that, The first air cooler and the second air cooler are installed in a cold storage, and the temperature of the cold storage is controlled below -22°C; the third air cooler is installed in a machine room, and the temperature of the machine room is controlled at 15°C - 20°C; the fourth air cooler is installed in an office area, and the temperature of the office area is controlled at 25°C - 28°C.

3. The LNG cascade cold energy utilization system according to claim 1, characterized in that, The refrigerant medium is R22, R410A or R32 working medium.

4. The LNG cascade cold energy utilization system according to claim 1, characterized in that, The inlet of the heat source channel of the second heat exchanger is connected to the equipment cooling water inlet pipeline, and the outlet of the refrigerant channel of the second heat exchanger is connected to the equipment cooling water outlet pipeline.

5. The LNG cascade cold energy utilization system according to claim 4, characterized in that, The cold source and the heat source in the second heat exchanger flow in opposite directions.

6. The LNG cascade cold energy utilization system according to claim 1, characterized in that, A pressure regulating valve is respectively provided on the first pipeline connected to the inlet of the internal coil of the first air cooler, the second pipeline connected to the outlet of the internal coil of the first air cooler, the fifth pipeline connected to the outlet of the internal coil of the second air cooler, the eighth pipeline connected to the outlet of the internal coil of the third air cooler, and the ninth pipeline connected to the inlet of the internal coil of the fourth air cooler.

7. The LNG cascade cold energy utilization system according to claim 1, characterized in that, A pressure regulating valve and a temperature transmitter are respectively provided on the third pipeline connecting the LNG fuel storage tank and the LNG vaporizer, the sixth pipeline connecting the LNG vaporizer and the first heat exchanger, and the seventh pipeline connecting the first heat exchanger and the second heat exchanger.

8. An LNG cascade cold energy utilization method based on the system according to any one of claims 1 to 7, characterized in that, The method is as follows: The LNG in the LNG fuel storage tank flows into the first air cooler through the self-booster. The LNG in the LNG fuel storage tank enters the LNG vaporizer. The LNG from the LNG vaporizer flows into the second air cooler to provide cooling capacity for the cold storage, so that the temperature of the cold storage is controlled below -22°C. The LNG flowing out of the LNG vaporizer enters the first heat exchanger to exchange heat with the refrigerant fluid. The refrigerant fluid enters the third air cooler to provide cooling capacity for the machine room, so that the temperature of the machine room is 15°C to 20°C. After flowing out of the third air cooler, the refrigerant fluid enters the fourth air cooler to provide cooling capacity for the office area, so that the temperature of the office area is 25°C to 28°C.

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