LNG cold energy recycling system and method

Abstract

The present application relates to LNG energy utilization technical field, disclose a kind of LNG cold energy recycling system and method, including LNG storage unit, gasifier, expansion generator, first heat exchanger, second heat exchanger, third heat exchanger and ice maker, gasifier is connected with LNG storage unit by pipeline;Expansion generator is connected between gasifier and first heat exchanger by pipeline, and first heat exchanger is used to connect with the pipe network of external device;Gasifier, first heat exchanger, second heat exchanger and third heat exchanger are also sequentially connected with load coolant circulation loop;Ice maker and second heat exchanger, third heat exchanger are also connected with cooling liquid circulation loop.The system is in the way of cold energy ladder utilization, so that gaseous natural gas is in heat generating unit and in ice making unit within ice making, and it can also use the way of adiabatic expansion to make natural gas produce more cold, improve the recycling efficiency of cold, reduce cold energy waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LNG energy utilization, in particular to an LNG cold energy recycling system and method. BACKGROUND

[0002] LNG is the abbreviation of Liquefied Natural Gas, which is a liquid obtained by compressing and cooling natural gas to its condensation point (-161.5℃). At present, in LNG receiving stations and gasification stations, LNG gasification mainly uses seawater or air as a heat source, or even uses a heating furnace as a supplementary heat source to make it re-gasify. The LNG absorbs the heat of seawater or air, i.e. releases cold energy to seawater or air, thereby gasifying into combustible natural gas.

[0003] A large amount of cold energy is released in the LNG gasification process. In the traditional process, not only the cold energy resources of LNG are not utilized, but also the ecological environment is damaged. New LNG receiving stations and gasification stations utilize the cold energy of LNG to make ice and other gases, thereby recycling and utilizing the cold energy of LNG. However, these receiving stations have problems in technology, region, economy, etc., and have poor universality, so they are not easy to popularize and use.

[0004] A patent with the authorized announcement number CN207894080U discloses an LNG cold energy recycling and energy storage ice making device, which comprises a first heat exchange system, a second heat exchange system and a third heat exchange system. The first heat exchange system comprises an LNG storage tank, an LNG booster pump, an LNG stop valve, an LNG regulating valve one, an LNG regulating valve two, an LNG heat exchanger and an LNG air cooler connected through an LNG pipeline. Liquid LNG is divided into two paths from the LNG storage tank through the LNG booster pump, one path directly enters the LNG air cooler to be gasified, and the other path enters the LNG heat exchanger to be heat exchanged and then enters the LNG air cooler. The second heat exchange system comprises a cold carrier liquid storage tank, a cold carrier circulating pump, a cold carrier heat exchanger and an LNG heat exchanger connected through a cold carrier pipeline. Cold carrier liquid is sequentially heat exchanged in the cold carrier heat exchanger and the LNG heat exchanger from the cold carrier liquid storage tank through the cold carrier circulating pump, and then returns to the cold carrier liquid storage tank. The third heat exchange system comprises a liquid storage tank, a liquid circulating pump, an ice maker and a cold carrier heat exchanger connected through a liquid pipeline. Non-freezing liquid is sequentially heat exchanged in the ice maker and the cold carrier heat exchanger from the liquid storage tank through the liquid circulating pump, and then returns to the liquid storage tank. The ice maker is connected with a tap water pipeline, and normal temperature water of the tap water pipeline is made into ice blocks of various shapes through the ice maker.

[0005] The LNG cold energy recycling and energy storage ice making device has three sets of heat exchange systems, LNG is first exchanged with a cold carrier, the cold carrier is then exchanged with liquid in a liquid pipeline, and finally, the cooled liquid is used for ice making. However, in the ice making process, part of the LNG directly enters an air cooler to be gasified into a gaseous state, and the cold energy of the LNG during the gasification is directly lost, resulting in low LNG cold energy recycling rate and waste of cold energy. SUMMARY

[0006] The LNG cold energy recycling system is provided to solve the problems of low cold energy recycling rate and waste in the prior art, and an LNG cold energy recycling method using the LNG cold energy recycling system is also provided.

[0007] To achieve the above-mentioned purpose, the LNG cold energy recycling system comprises an LNG storage unit, a gasifier, an expansion generator, a first heat exchanger, a second heat exchanger, a third heat exchanger and an ice maker. The gasifier is connected to the LNG storage unit through a pipeline and is used for heat absorption and gasification of LNG to form gaseous natural gas.

[0008] The expansion generator is connected between the gasifier and the first heat exchanger through a pipeline, and is used for adiabatic expansion and power generation of the gaseous natural gas and for recooling. The first heat exchanger is connected to an external pipe network, and is used for heat exchange and temperature rise of the re-cooled gaseous natural gas, and then the gaseous natural gas is expanded and enters the pipe network. The gasifier, the expansion generator and the first heat exchanger form a heat exchange and power generation unit.

[0009] The gasifier, the first heat exchanger, the second heat exchanger and the third heat exchanger are further sequentially connected to a cold carrier circulation loop. The cold carrier circulation loop is used for circulation of the cold carrier. The cold carrier exchanges heat with the gaseous natural gas in the first heat exchanger and the gasifier to be cooled. The cold carrier exchanges heat with the cooling liquid in the second heat exchanger and the third heat exchanger to be heated.

[0010] The ice maker is further connected to the second heat exchanger and the third heat exchanger through a cooling liquid circulation loop. The cooling liquid circulation loop is used for circulation of the cooling liquid. The cooling liquid exchanges heat with the cold carrier in the second heat exchanger and the third heat exchanger to be cooled. The cooling liquid exchanges heat with the ice maker in the ice maker to be heated. The ice maker is used for ice making by absorbing the cold energy of the cooling liquid. The gasifier, the first heat exchanger, the second heat exchanger, the third heat exchanger and the ice maker form an ice making unit.

[0011] Preferably, the LNG storage unit comprises a storage tank, a buffer tank and a booster pump connected between the storage tank and the buffer tank, and the gasifier is connected to the buffer tank through a pipeline.

[0012] Preferably, the system further comprises an electrolytic water unit comprising an electrolytic tank, a hydrogen delivery pipe and an oxygen delivery pipe, both of which are in communication with the electrolytic tank, and the electrolytic tank is electrically connected to the expansion generator for providing electric energy to the electrolytic tank.

[0013] Preferably, a fourth heat exchanger is further connected to the oxygen delivery pipe and arranged in the buffer tank, and the fourth heat exchanger is used for heat exchange between oxygen and liquefied natural gas.

[0014] Preferably, booster pumps are arranged on the oxygen delivery pipe and the hydrogen delivery pipe.

[0015] Preferably, circulating pumps are arranged on the coolant circulation loop and the cooling liquid circulation loop.

[0016] Preferably, the cooling liquid in the cooling liquid circulation loop is a glycol solution.

[0017] The application also provides an LNG cold energy recycling method using the LNG cold energy recycling system according to any one of the above technical solutions, comprising the following steps:

[0018] S1, the liquefied natural gas in the LNG storage unit enters the gasifier, expands into gaseous natural gas by heat absorption in the gasifier, enters the expansion generator, and generates electricity by adiabatic expansion in the expansion generator, and then the natural gas after adiabatic expansion enters the first heat exchanger after cooling;

[0019] S2, the coolant circulates in the coolant circulation loop, exchanges heat with the gaseous natural gas in the gasifier and the first heat exchanger, cools down after heat release, and then exchanges heat with the cooling liquid in the second heat exchanger and the third heat exchanger;

[0020] S3, the cooling liquid circulates in the cooling liquid circulation loop, exchanges heat with the coolant in the second heat exchanger and the third heat exchanger, cools down after heat release, and then absorbs heat in the ice maker to increase the temperature;

[0021] S4, the water in the ice maker exchanges heat with the cooling heat, and solidifies into ice after heat release.

[0022] Preferably, in step S1, the liquefied natural gas in the LNG storage unit is pressurized by the booster pump after entering the buffer tank from the storage tank, so that the liquefied natural gas is warmed up.

[0023] Preferably, in step S1, the expanded generator generates electricity, and the electricity is transmitted to an electrolytic cell of the water electrolysis unit, the electrolytic cell electrolyzes water to produce hydrogen and oxygen, the oxygen is transmitted to the fourth heat exchanger by a booster pump, and the oxygen is heat-exchanged with the liquefied natural gas in the buffer tank in the fourth heat exchanger to generate liquid oxygen by heat release.

[0024] Compared with the prior art, the LNG cold energy recycling system and method has the beneficial effects that: the liquefied natural gas enters the heat exchange generator unit before entering the pipe network, is heat-absorbed and gasified into gaseous natural gas in the gasifier of the heat exchange generator unit, is heat-released and reduced in temperature after generating electricity in the expanded generator, is heat-exchanged with the cold carrier in the first heat exchanger to reduce the temperature of the cold carrier, flows in the cold carrier circulation loop, is heat-exchanged with the cooling liquid flowing in the cooling liquid circulation loop in the second heat exchanger and the third heat exchanger to reduce the temperature of the cooling liquid, and performs ice-making operation in the ice maker; the system uses the cold energy step-by-step utilization mode to make the gaseous natural gas generate electricity in the heat exchange generator unit and make ice in the ice-making unit, and can also use the adiabatic expansion mode to make the natural gas generate more cold energy, improve the cold energy recycling efficiency, and reduce the cold energy waste; when the LNG gasification amount fluctuates, the temperature of the cold carrier and the ice-making amount can be adjusted to realize energy storage, store the cold energy, automatically adjust the system cold energy, and ensure the constant temperature of the system; the components of the system can be centrally assembled and integrated, the construction cost is low, the resistance is small, the maintenance is convenient, and the service life is long. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the LNG cold energy recycling system of the present application.

[0026] In the figure, 1 is a storage tank, 2 is a buffer tank, 3 is a gasifier, 4 is an expanded generator, 5 is a first heat exchanger, 6 is a second heat exchanger, 7 is a third heat exchanger, 8 is a fourth heat exchanger, 9 is an ice maker, 10 is a cold carrier circulation loop, 11 is a cooling liquid circulation loop, 12 is a circulating pump, 13 is a hydrogen gas transmission pipe, 14 is an oxygen gas transmission pipe, 15 is a booster pump, 16 is a check valve, and 17 is an electrolytic cell. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application are described in further detail below in combination with the drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0028] A preferred embodiment of the LNG cold energy recycling system of the present application is as follows: Figure 1As shown, the LNG cold energy recovery and utilization system includes an LNG storage unit, a vaporizer 3, an expander generator 4, a first heat exchanger 5, a second heat exchanger 6, a third heat exchanger 7, and an ice maker 9. The LNG storage unit is used to store liquefied natural gas under high pressure.

[0029] The vaporizer 3 is connected to the LNG storage unit via a pipeline. The vaporizer 3 is used to vaporize LNG by absorbing heat to form gaseous natural gas. During the vaporization process, the LNG absorbs a large amount of heat through a refrigerant, thus releasing a large amount of cold energy. The expander generator 4 is connected to the vaporizer 3 and the first heat exchanger 5 via a pipeline. The first heat exchanger 5 is used to connect to an external pipeline network to transport the gaseous natural gas to the natural gas transmission network. The vaporizer 3, the expander generator 4, and the first heat exchanger 5 form a heat exchange and power generation unit.

[0030] After absorbing heat and vaporizing in the vaporizer 3, the liquefied natural gas (LNG) enters the expander generator 4 to generate electricity. Within the expander generator 4, it undergoes adiabatic expansion, during which the temperature of the gaseous natural gas decreases again, accumulating cold energy once more. It then enters the first heat exchanger 5 for heat exchange and pressure increase. In the first heat exchanger 5, the gaseous natural gas absorbs heat and releases cold energy to the refrigerant. After expansion, the temperature and pressure of the gaseous natural gas increase, and it is supplied to the pipeline network at a certain pressure. The pressure of the gaseous natural gas supplied to the pipeline network meets the network's needs.

[0031] A refrigerant circulation loop 10 is sequentially connected between the vaporizer 3, the first heat exchanger 5, the second heat exchanger 6, and the third heat exchanger 7. The refrigerant circulation loop 10 is used to circulate the refrigerant. The refrigerant circulates in the refrigerant circulation pipeline. In the first heat exchanger 5 and the vaporizer 3, it exchanges heat with gaseous natural gas to cool it down, carrying away the cold energy of the natural gas. Then, in the second heat exchanger 6 and the third heat exchanger 7, it exchanges heat with the coolant to raise its temperature, transferring the cold energy to the coolant and lowering the temperature of the coolant.

[0032] A coolant circulation loop 11 is also connected between the ice maker 9 and the second heat exchanger 6 and the third heat exchanger 7, providing a circulating flow of coolant. During the flow of coolant in the coolant circulation loop 11, it exchanges heat with the refrigerant in the second heat exchanger 6 and the third heat exchanger 7 to cool down, carrying away the cold energy of the refrigerant. Then, it exchanges heat with the ice maker 9 to raise its temperature, allowing the ice maker 9 to absorb cold energy and make ice.

[0033] Ice maker 9 is connected to a tap water pipe. The room-temperature water in the tap water pipe absorbs the cold energy of the coolant in ice maker 9 and freezes into ice, thus producing ice blocks of various shapes as needed. Vaporizer 3, first heat exchanger 5, second heat exchanger 6, third heat exchanger 7, and ice maker 9 form an ice-making unit. Depending on the amount of LNG to be vaporized, and while ensuring a constant process temperature, the temperature of each component can be adjusted to maintain a constant system temperature by regulating the amount of ice produced.

[0034] This LNG cold energy recovery and utilization system utilizes a tiered approach to cold energy, enabling gaseous natural gas to generate electricity in the heat exchange power generation unit and produce ice in the ice-making unit. Simultaneously, it leverages adiabatic expansion to generate even more cooling energy from the natural gas, improving cold energy recovery and utilization efficiency and reducing cold energy waste. When LNG vaporization fluctuates, energy storage can be achieved by adjusting the temperature of the refrigerant and the ice-making rate, storing and automatically regulating the system's cooling capacity to ensure a constant system temperature. All components of this system can be centrally assembled, resulting in low construction costs, low resistance, convenient maintenance, and a long service life.

[0035] Preferably, the LNG storage unit includes a storage tank 1, a buffer tank 2, and a booster pump 15. The booster pump 15 is connected between the storage tank 1 and the buffer tank 2, and the vaporizer 3 is connected to the buffer tank 2 through a pipeline.

[0036] Storage tank 1 stores LNG to be vaporized. Booster pump 15 pressurizes the LNG and delivers it into buffer tank 2, where the LNG is heated or partially vaporized. By first pressurizing the LNG, its temperature can be increased, allowing for partial vaporization and improving vaporization efficiency. In this embodiment, a check valve 16 is also installed on the pipeline between booster pump 15 and buffer tank 2 to prevent high-pressure LNG from flowing back into storage tank 1.

[0037] Preferably, it also includes a water electrolysis unit, which includes an electrolysis cell 17, a hydrogen delivery pipe 13 and an oxygen delivery pipe 14. The hydrogen delivery pipe 13 and the oxygen delivery pipe 14 are both connected to the electrolysis cell 17. The electrolysis cell 17 is electrically connected to an expansion generator 4, which is used to provide electrical energy to the electrolysis cell 17.

[0038] The electrical energy generated by the expander generator 4 is directly transmitted to the electrolyzer 17 for use in the motor. Hydrogen and oxygen can be obtained simultaneously through water electrolysis. The hydrogen and oxygen are then transmitted to external pipelines through the hydrogen transmission pipe 13 and the oxygen transmission pipe 14, respectively. This realizes the production of hydrogen and oxygen using LNG cold energy and improves the utilization rate of cold energy.

[0039] Preferably, a fourth heat exchanger 8 is also connected to the oxygen delivery pipe 14. The fourth heat exchanger 8 is arranged inside the buffer tank 2 and is used to exchange heat and cool the oxygen with the liquefied natural gas.

[0040] The fourth heat exchanger 8 is located inside the buffer tank 2. After entering the fourth heat exchanger 8, the oxygen exchanges heat with the pressurized liquefied natural gas (LNG) to cool down. The oxygen absorbs the cold energy of the LNG, its temperature decreases, and it liquefies, facilitating oxygen transportation. The oxygen liquefaction process is completed using the LNG in the buffer tank 2, making reasonable use of the LNG's cold energy and improving the cold energy utilization rate.

[0041] Preferably, both the oxygen delivery pipe 14 and the hydrogen delivery pipe 13 are equipped with booster pumps 15.

[0042] The booster pump 15 provides power for the delivery of oxygen and hydrogen, facilitating their output to external pipelines for sale.

[0043] Preferably, a circulation pump 12 is arranged on both the refrigerant circulation loop 10 and the coolant circulation loop 11.

[0044] The circulating pump 12 provides power support for the circulating flow of the refrigerant and coolant.

[0045] Preferably, the coolant material in the coolant circulation loop 11 is an ethylene glycol solution.

[0046] Ethylene glycol solution is used as the coolant because it is readily available, inexpensive, and has low operating costs.

[0047] The present invention also provides an embodiment of an LNG cold energy recovery and utilization method. The LNG cold energy recovery and utilization system using any of the above embodiments includes the following steps:

[0048] S1, the liquefied natural gas in the LNG storage unit enters the vaporizer 3, absorbs heat and expands into gaseous natural gas in the vaporizer 3, the gaseous natural gas enters the expansion generator 4, adiabatic expansion and power generation occur in the expansion generator 4, and the adiabatic expanded natural gas is cooled and enters the first heat exchanger 5.

[0049] S2, the refrigerant circulates in the refrigerant circulation loop 10, and the refrigerant exchanges heat with gaseous natural gas in the vaporizer 3 and the first heat exchanger 5. After the refrigerant releases heat and cools down, it exchanges heat with the coolant in the second heat exchanger 6 and the third heat exchanger 7 to raise its temperature.

[0050] S3, the coolant circulates in the coolant circulation loop 11, and the coolant exchanges heat with the refrigerant in the second heat exchanger 6 and the third heat exchanger 7. After the coolant releases heat and cools down, it absorbs heat and heats up in the ice maker 9.

[0051] S4, the water in the ice maker 9 exchanges heat with the cooling heat, and the water freezes into ice after releasing heat.

[0052] The vaporizer 3, the expander generator 4, and the first heat exchanger 5 form a heat exchange power generation unit. The vaporizer 3, the first heat exchanger 5, the second heat exchanger 6, the third heat exchanger 7, and the ice maker 9 form an ice making unit. The cold energy of LNG is utilized in stages through the heat exchange power generation unit and the ice making unit to improve the cold energy utilization rate. At the same time, when LNG expands adiabatically in the expander generator 4, it will generate more cold energy, resulting in high cold energy recovery efficiency.

[0053] When the LNG vaporization rate fluctuates, energy storage can be achieved by adjusting the temperature of the refrigerant and the amount of ice produced. The cold energy is then stored and automatically adjusted to ensure a constant system temperature. Therefore, this method has an energy storage function and can be independently and automatically adjusted according to the LNG gas volume load.

[0054] Preferably, in step S1, the liquefied natural gas in the LNG storage unit is pressurized by the storage tank 1 via the booster pump 15 before entering the gasifier 3, thereby raising the temperature of the liquefied natural gas.

[0055] Storage tank 1 stores LNG to be vaporized. Booster pump 15 pressurizes the LNG and delivers it into buffer tank 2, where the LNG is heated or partially vaporized. By first pressurizing the LNG, its temperature can be increased, allowing for partial vaporization and improving vaporization efficiency. In this embodiment, a check valve 16 is also installed on the pipeline between booster pump 15 and buffer tank 2 to prevent high-pressure LNG from flowing back into storage tank 1.

[0056] Preferably, in step S1, after the expansion generator 4 generates electricity, it transmits the electrical energy to the electrolyzer 17 of the water electrolysis unit. The electrolyzer 17 electrolyzes water to produce hydrogen and oxygen. The oxygen is transported to the fourth heat exchanger 8 through the booster pump 15. In the fourth heat exchanger 8, it exchanges heat with the liquefied natural gas in the buffer tank 2 and releases heat to generate liquid oxygen.

[0057] The water electrolysis unit can not only use the electricity generated by the LNG cooling capacity to directly produce gases such as hydrogen and oxygen, thus converting the hard-to-store electrical energy into chemical energy, but also use the LNG in buffer tank 2 to liquefy oxygen and directly generate liquid oxygen, further improving the utilization rate of cooling capacity.

[0058] In summary, this invention provides an LNG cold energy recovery and utilization system and method. Before entering the pipeline network, the liquefied natural gas (LNG) first enters a heat exchange and power generation unit. In the vaporizer of the heat exchange and power generation unit, it absorbs heat and vaporizes to form gaseous natural gas. After generating electricity and releasing heat in the expansion generator, the gaseous natural gas cools down and enters the first heat exchanger to exchange heat with the refrigerant, thus cooling the refrigerant. The refrigerant flows in the refrigerant circulation loop. In the second and third heat exchangers, it exchanges heat with the coolant flowing in the coolant circulation loop, thus lowering the coolant temperature. The coolant then performs ice-making operations in the ice maker. The system utilizes a tiered approach to cold energy utilization, enabling gaseous natural gas to generate electricity in the heat exchange power generation unit and produce ice in the ice-making unit. Simultaneously, it leverages adiabatic expansion to generate even more cooling from the natural gas, improving the efficiency of cold energy recovery and reducing waste. When LNG vaporization fluctuates, energy storage can be achieved by adjusting the temperature of the refrigerant and the ice-making rate, storing and automatically regulating the system's cooling capacity to maintain a constant temperature. All components of the system can be assembled as a single unit, resulting in low construction costs, low resistance, convenient maintenance, and a long service life.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. An LNG cold energy recovery and utilization system, characterized in that, It includes an LNG storage unit, a vaporizer, an expander generator, a first heat exchanger, a second heat exchanger, a third heat exchanger, and an ice maker. The vaporizer is connected to the LNG storage unit via a pipeline and is used to supply heat to the LNG for vaporization to form gaseous natural gas. The expansion generator is connected between the gasifier and the first heat exchanger via a pipeline. The expansion generator is used to supply gaseous natural gas for adiabatic expansion to generate electricity and then cool it down again. The first heat exchanger is used to connect to an external pipeline network. The first heat exchanger supplies the cooled gaseous natural gas to exchange heat, heat up, expand, and then enter the pipeline network. The gasifier, the expansion generator, and the first heat exchanger form a heat exchange power generation unit. A refrigerant circulation loop is sequentially connected between the gasifier, the first heat exchanger, the second heat exchanger, and the third heat exchanger. The refrigerant circulation loop is used to circulate the refrigerant. The refrigerant exchanges heat with gaseous natural gas in the first heat exchanger and the gasifier to cool down, and exchanges heat with coolant in the second heat exchanger and the third heat exchanger to raise its temperature. A coolant circulation loop is also connected between the ice maker and the second and third heat exchangers. The coolant circulation loop allows coolant to circulate. The coolant exchanges heat with the refrigerant in the second and third heat exchangers to cool down, and exchanges heat with the ice maker in the ice maker to raise its temperature. The ice maker is used to absorb the cold energy of the coolant to make ice. The vaporizer, the first heat exchanger, the second heat exchanger, the third heat exchanger, and the ice maker together form an ice-making unit.

2. The LNG cold energy recovery and utilization system according to claim 1, characterized in that, The LNG storage unit includes a storage tank, a buffer tank, and a booster pump. The booster pump is connected between the storage tank and the buffer tank, and the vaporizer is connected to the buffer tank via a pipeline.

3. The LNG cold energy recovery and utilization system according to claim 2, characterized in that, It also includes a water electrolysis unit, which includes an electrolysis cell, a hydrogen delivery pipe and an oxygen delivery pipe. The hydrogen delivery pipe and the oxygen delivery pipe are both connected to the electrolysis cell. The electrolysis cell is electrically connected to the expansion generator, which is used to provide electrical energy to the electrolysis cell.

4. The LNG cold energy recovery and utilization system according to claim 3, characterized in that, A fourth heat exchanger is also connected to the oxygen delivery pipe. The fourth heat exchanger is arranged inside the buffer tank and is used to exchange heat and cool the oxygen with the liquefied natural gas.

5. The LNG cold energy recovery and utilization system according to claim 4, characterized in that, Both the oxygen delivery pipe and the hydrogen delivery pipe are equipped with booster pumps.

6. The LNG cold energy recovery and utilization system according to any one of claims 1-4, characterized in that, Both the refrigerant circulation loop and the coolant circulation loop are equipped with circulation pumps.

7. The LNG cold energy recovery and utilization system according to any one of claims 1-4, characterized in that, The coolant in the coolant circulation loop is an ethylene glycol solution.

8. A method for recovering and utilizing LNG cold energy, using the LNG cold energy recovery and utilization system according to any one of claims 1-7, characterized in that, Includes the following steps: S1, the liquefied natural gas in the LNG storage unit enters the gasifier, absorbs heat and expands into gaseous natural gas in the gasifier, the gaseous natural gas enters the expansion generator, adiabatic expansion and power generation occur in the expansion generator, and the adiabatic expanded natural gas is cooled and enters the first heat exchanger. S2, the refrigerant circulates in the refrigerant circulation loop. The refrigerant exchanges heat with gaseous natural gas in the vaporizer and the first heat exchanger. After the refrigerant releases heat and cools down, it exchanges heat with the coolant in the second and third heat exchangers and heats up. S3, the coolant circulates in the coolant circulation loop, and the coolant exchanges heat with the refrigerant in the second and third heat exchangers. After the coolant releases heat and cools down, it absorbs heat and heats up in the ice maker. S4, the water in the ice maker exchanges heat with the cooling heat, and the water freezes into ice after releasing heat.

9. The LNG cold energy recovery and utilization method according to claim 8, characterized in that, In step S1, before entering the vaporizer, the liquefied natural gas in the LNG storage unit is pressurized by a booster pump from the storage tank and then enters the buffer tank, which causes the liquefied natural gas to heat up.

10. The LNG cold energy recovery and utilization method according to claim 9, characterized in that, In step S1, after the expansion generator generates electricity, it transmits the electrical energy to the electrolyzer of the water electrolysis unit. The electrolyzer electrolyzes water to produce hydrogen and oxygen. The oxygen is then transported to the fourth heat exchanger by a booster pump. In the fourth heat exchanger, the oxygen exchanges heat with the liquefied natural gas in the buffer tank and releases heat to generate liquid oxygen.

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