Cold energy recycling system of LNG (Liquefied Natural Gas) filling and hydrogenation combined building station and use method of cold energy recycling system

Abstract

The invention discloses a cold energy recycling system of an LNG (Liquefied Natural Gas) filling and hydrogenation combined building station and a use method of the cold energy recycling system. A first pressure and temperature monitor and a first switch valve are arranged on a pipeline between a boil-off gas main pipe and a boil-off gas air temperature type heat exchanger; a second switch valve is connected between the air inlet end of the first switch valve and the first pressure and temperature monitor through a tee joint; the other end of the second switch valve is sequentially connected with a coil heat exchanger and a second pressure and temperature monitor; a second pressure and temperature monitor is respectively connected with a fourth switch valve and a first check valve through a tee joint; the other end of the fourth switch valve is connected with the shell-and-tube heat exchanger; the other end of the first check valve is respectively connected with a third switch valve and a fifth switch valve through a tee joint; and the other end of the third switch valve is respectively connected with a pipeline between the evaporated gas air temperature type heat exchanger and the evaporated gas utilization system and the sleeve type heat exchanger through a tee joint. According to the system and the method, the asynchronous functions of the LNG gas filling and hydrogenation combined building station are effectively linked and fully utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of cold energy recovery of an LNG gasification and hydrogenation combined station, and in particular to a cold energy recovery and utilization system of an LNG gasification and hydrogenation combined station and a method for using the same. Background Art

[0002] In the existing technology, no cold energy recovery measures are taken in LNG gasification and hydrogenation combined stations, and the cold energy released by LNG during evaporation and gasification is released into the environment and wasted.

[0003] For example, the publication number CN114893719A discloses a BOG gas recovery system and method for a combined hydrogenation and liquefied natural gas (LNG) refueling station, and the publication number CN219995052U discloses a liquefied natural gas cold energy recovery and utilization system.

[0004] Among them, the former uses the cold energy of liquid hydrogen to provide corresponding cold energy for the BOG recovery process, and although the latter proposes that the cold energy of LNG gasification can be recycled, the solution is to store the cold energy in coolants such as ethylene glycol, and use the coolant to perform heat exchange with hydrogen. As a whole, a gradient utilization method has not been formed.

[0005] Therefore, how to efficiently recover and cascade utilize the low-temperature boil-off gas formed by environmental influences during the storage process of LNG, especially when the LNG refueling and hydrogenation combined station is in operation, not all functions are carried out simultaneously. How to effectively connect the various utilization methods to ensure that the cold energy can be fully utilized and avoid waste has become a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a cold energy recovery and utilization system for an LNG gasification and hydrogenation combined station and a method for using the same, the purpose of which is to efficiently recover and cascade utilize the low-temperature evaporated gas formed by environmental influences during the storage process of LNG. In particular, when the LNG gasification and hydrogenation combined station is in operation, the functions that are not performed simultaneously are effectively connected to ensure that the cold energy can be fully utilized and waste is avoided.

[0007] To achieve the above objectives, the present invention discloses a cold energy recovery and utilization system for an LNG gasification and hydrogenation combined station, including a boil-off gas and low-temperature vented gas recovery section, a hydrogenator, a shell and tube heat exchanger, and a jacket heat exchanger.

[0008] The evaporation gas and low-temperature vented gas recovery part includes an evaporation gas air-temperature heat exchanger whose air inlet is connected to the evaporation gas main pipe and whose air outlet is connected to the evaporation gas utilization system;

[0009] A first pressure and temperature monitoring device and a first switch valve are provided on the pipeline between the evaporation gas main pipe and the evaporation gas air-temperature heat exchanger;

[0010] A second switch valve is connected between the air inlet end of the first switch valve and the first pressure and temperature monitoring via a three-way connection;

[0011] The other end of the second on-off valve is connected in sequence to the coil heat exchanger and the second pressure and temperature monitoring;

[0012] Hydrogen is introduced into another pipeline of the coil heat exchanger for heat exchange, and the gas outlet is connected to the hydrogenator for supplying hydrogen to the hydrogenator;

[0013] The second pressure and temperature monitoring are respectively connected to the fourth switch valve and the first check valve through a three-way connection;

[0014] The other end of the fourth switch valve is connected to the cooling medium pipeline of the shell and tube heat exchanger;

[0015] The other end of the first check valve is connected to the third switch valve and the fifth switch valve through a tee;

[0016] The other end of the third switch valve is connected to the pipeline between the evaporative gas air-temperature heat exchanger and the evaporative gas utilization system, and the cooling medium pipeline of the shell-and-shell heat exchanger through a tee;

[0017] The other end of the fifth switch valve is connected to the cooling medium pipeline of the shell and tube heat exchanger and the cooling medium pipeline of the jacket heat exchanger through a tee;

[0018] A fourth pressure and temperature monitor is provided between the fifth switch valve and the shell and tube heat exchanger, and a sixth switch valve is provided between the fifth switch valve and the jacket-and-sleeve heat exchanger.

[0019] Preferably, the cooling medium pipeline of the shell and tube heat exchanger forms a cycle with the hydrogen compressor cooling device and the refrigerator connected in sequence;

[0020] The inlet of the cooled medium pipeline of the shell and tube heat exchanger is connected to the refrigerant outlet of the refrigerator, and an eighth switch valve is provided on the pipeline therebetween;

[0021] The outlet of the cooled medium pipeline of the shell and tube heat exchanger is connected to the refrigerant inlet of the hydrogen compressor cooling device, and a fifth pressure and temperature monitoring device is provided on the pipeline therebetween;

[0022] The pipeline from the refrigerator to the eighth switch valve and the pipeline from the shell and tube heat exchanger to the fifth pressure and temperature monitoring are connected to the seventh switch valve through two three-way connections respectively.

[0023] Preferably, the inlet of the cooled medium pipeline of the jacketed heat exchanger is connected to the domestic water main to obtain domestic water, and a ninth switch valve is provided between the inlet and the domestic water main;

[0024] The outlet of the cooled medium pipeline of the jacketed heat exchanger is connected to the LNG filling hood and the hydrogenation hood, and the pipelines therebetween are provided with a plurality of atomizing joints at the parts close to the LNG filling hood and the hydrogenation hood;

[0025] The pipeline from the domestic water main to the ninth switch valve and the pipeline from the shell-and-shell heat exchanger to the atomizing meeting head are connected to the tenth switch valve through two three-way connections respectively.

[0026] The present invention also provides a method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station.

[0027] When there is no hydrogenation operation, the first on-off valve is opened, the second on-off valve is closed, and the bleed gas is heated by the evaporation gas air-to-air heat exchanger and then enters the evaporation gas utilization system for processing;

[0028] When hydrogenation is in progress, the first on-off valve is closed and the second on-off valve is opened to send the low-temperature boil-off gas out from the second on-off valve;

[0029] Preferably, when the temperature measured by the second pressure and temperature monitoring is less than -30°C, the third on-off valve and the fifth on-off valve are closed, and the fourth on-off valve is opened to allow natural gas to enter the cooling medium pipeline of the shell and tube heat exchanger for heat exchange;

[0030] When the temperature measured by the second pressure and temperature monitoring is greater than or equal to -30°C and less than or equal to 0°C, the third on-off valve and the fourth on-off valve are closed, and the fifth on-off valve and the sixth on-off valve are opened to allow natural gas to enter the cooling medium pipeline of the shell-and-shell heat exchanger for heat exchange;

[0031] When the temperature measured by the second pressure and temperature monitoring is greater than 0° C., the fourth switch valve is closed, and the third switch valve and the fifth switch valve are opened to allow natural gas to enter the boil-off gas utilization system.

[0032] Preferably, the freezer is a temperature-adjustable freezer;

[0033] When the shell and tube heat exchanger is not performing heat exchange, the temperature of the refrigerator is adjusted to the temperature required for compressor cooling, the eighth switch valve is closed, and the seventh switch valve is opened for operation;

[0034] When the shell and tube heat exchanger performs heat exchange, the seventh switch valve is closed, the eighth switch valve is opened for operation, and the temperature of the refrigerator is interlocked and adjusted with the fifth pressure and temperature monitoring;

[0035] In the shell and tube heat exchanger, the refrigerant flows through the shell side and the natural gas flows through the tube side for heat exchange.

[0036] Preferably, when the temperature measured by the fourth pressure and temperature monitoring is greater than or equal to 5° C., the third on-off valve and the fifth on-off valve are opened, and the sixth on-off valve is closed, so that natural gas enters the boil-off gas utilization system;

[0037] When the temperature measured by the fourth pressure and temperature monitoring is less than 5°C, the fifth switch valve is closed and the sixth switch valve is opened, and natural gas enters the cooling medium pipeline of the shell-and-shell heat exchanger for heat exchange;

[0038] When the sixth switch valve is opened, the ninth switch valve is opened and the tenth switch valve is closed;

[0039] When the sixth switching valve is closed, the ninth switching valve is closed, and the tenth switching valve is opened.

[0040] Beneficial effects of the present invention:

[0041] The present invention pre-cools the added hydrogen through low-temperature natural gas, which can reduce the hydrogen temperature by about 15°C, eliminating the restriction of the negative coke effect on the hydrogen filling speed in the existing hydrogenation process, and effectively improving the hydrogen filling speed.

[0042] The cooling liquid used in the cooling system of the hydrogen compressor of the present invention is heat exchanged with the low-temperature natural gas after pre-cooling the hydrogen, thereby realizing the second-level utilization of cold energy.

[0043] The natural gas after heat exchange in the compressor cooling system of the present invention can be further heat exchanged with the cooling spray water of the filling canopy, thereby providing heatstroke prevention and cooling services for the vehicle and the driver and passengers.

[0044] The present invention sets up multiple temperature and pressure detection points in the system, which can effectively monitor the operating status of the system and control the action of the switch valve to realize the regulation of cooling in the station, eliminating the adverse effect of the prior art that the temperature of the heat exchange object is not a constant value because the operation of the combined station is not simultaneous operation of gas and hydrogen.

[0045] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A structural diagram of an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0047] Example

[0048] like Figure 1 As shown, the cold energy recovery and utilization system of the LNG refueling and hydrogenation combined station includes a boil-off gas and low-temperature vented gas recovery part 1, a hydrogenator 2, a shell and tube heat exchanger 3 and a jacket heat exchanger 4.

[0049] The evaporation gas and low-temperature vent gas recovery part 1 includes an evaporation gas air-temperature heat exchanger 12 connected to the evaporation gas main pipe 11 at the air inlet end and the evaporation gas utilization system 13 at the air outlet end;

[0050] A first pressure and temperature monitoring device TT1 and a first switch valve a1 are provided on the pipeline between the evaporation gas main pipe 11 and the evaporation gas air-temperature heat exchanger 12;

[0051] The air inlet end of the first switch valve a1 is connected to the first pressure and temperature monitoring TT1 via a three-way connection to the second switch valve a2;

[0052] The other end of the second on-off valve a2 is connected in sequence to the coil heat exchanger 5 and the second pressure and temperature monitoring TT2;

[0053] Hydrogen is introduced into the other pipeline of the coil heat exchanger 5 for heat exchange, and the gas outlet is connected to the hydrogenator 2 for supplying hydrogen to the hydrogenator 2;

[0054] The second pressure and temperature monitoring TT2 is connected to the fourth switch valve a4 and the first check valve b1 through a three-way connection;

[0055] In practical applications, the presence of the first check valve b1 can prevent the natural gas with a higher temperature from mixing with the natural gas at a lower temperature, thereby preventing the heat exchange effect of the compressor heat exchange system from being reduced.

[0056] The other end of the fourth switch valve a4 is connected to the cooling medium pipeline of the shell and tube heat exchanger 3;

[0057] The other end of the first check valve b1 is connected to the third switch valve a3 and the fifth switch valve a5 through a three-way connection;

[0058] The other end of the third switch valve a3 is connected to the pipeline between the evaporative gas air-temperature heat exchanger 12 and the evaporative gas utilization system 13, as well as the cooling medium pipeline of the shell-and-shell heat exchanger 4 through a tee;

[0059] The other end of the fifth switch valve a5 is connected to the cooling medium pipeline of the shell and tube heat exchanger 3 and the cooling medium pipeline of the jacket heat exchanger 4 through a tee;

[0060] A fourth pressure and temperature monitoring valve TT4 is provided between the fifth switch valve a5 and the shell and tube heat exchanger 3 , and a sixth switch valve a6 is provided between the fifth switch valve a5 and the jacket-and-sleeve heat exchanger 4 .

[0061] In some embodiments, the cooled medium pipeline of the shell and tube heat exchanger 3 forms a cycle with the hydrogen compressor cooling device 6 and the refrigerator 7 connected in sequence;

[0062] The inlet of the cooled medium pipeline of the shell and tube heat exchanger 3 is connected to the refrigerant outlet of the refrigerator 7, and an eighth switch valve a8 is provided on the pipeline therebetween;

[0063] The outlet of the cooled medium pipeline of the shell and tube heat exchanger 3 is connected to the refrigerant inlet of the hydrogen compressor cooling device 6, and a fifth pressure and temperature monitoring device TT5 is provided on the pipeline therebetween;

[0064] In actual application, the pipeline from the refrigerator 7 to the eighth switch valve a8 and the pipeline from the shell and tube heat exchanger 3 to the fifth pressure and temperature monitoring TT5 are connected to the seventh switch valve a7 through two three-way connections respectively. The temperature of the evaporated LNG from the hydrogenation heat exchange is about -30°C, while the temperature of the refrigerator 7 is only about -5°C. After being used in the hydrogen compressor cooling device 6, the outlet temperature can reach above 20°C.

[0065] Therefore, the refrigerator 7 is actually a dual-function device, that is, when the cold energy cascade utilization can proceed normally to this step, the refrigerator 7 is in an abnormal start-up mode, which is a passage. The switch valve 8 can be opened to provide the cold energy required for cooling the hydrogen compressor cooling device 6 through heat exchange. If this step is skipped, then the valve 8 is closed and the valve 7 is opened for the refrigerator to work normally.

[0066] In some embodiments, the inlet of the cooled medium pipeline of the jacketed heat exchanger 4 is connected to the domestic water main 8 to obtain domestic water, and a ninth switch valve a9 is provided between the inlet and the domestic water main 8;

[0067] The outlet of the cooled medium pipeline of the jacketed heat exchanger 4 is connected to the LNG filling hood and the hydrogenation hood 9, and the pipelines therebetween are provided with a plurality of atomizing bumpers 10 near the LNG filling hood and the hydrogenation hood 9;

[0068] The pipeline from the domestic water main 8 to the ninth switch valve a9 and the pipeline from the jacketed heat exchanger 4 to the atomizing joint 10 are connected to the tenth switch valve a10 through two three-way connections respectively.

[0069] The present invention also provides a method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station:

[0070] When there is no hydrogenation operation, the first switch valve a1 is opened and the second switch valve a2 is closed, and the vented gas is heated by the evaporation gas air-heat heat exchanger 12 and then enters the evaporation gas utilization system 13 for treatment;

[0071] When hydrogenation is in progress, the first on-off valve a1 is closed and the second on-off valve a2 is opened, sending the low-temperature evaporated gas out from the second on-off valve a2.

[0072] In practical applications, since the stainless steel material used for the hydrogen pipeline in the hydrogen filling station can withstand low temperatures, the first stage of heat exchange is a coil heat exchanger 5 arranged in front of the hydrogenator 2. The present invention sends the low-temperature evaporated gas led out by the second switching valve a2 into the coil heat exchanger 5 with the hydrogen flowing through the inner pipe, allowing the low-temperature natural gas to flow through the outer pipe for countercurrent heat exchange. After heat exchange, the temperature of the hydrogen can be reduced by about 15°C, which can effectively increase the hydrogen filling speed without causing overheating due to the soup-coke effect.

[0073] In some embodiments, when the temperature measured by the second pressure and temperature monitoring device TT2 is less than -30°C, the third on-off valve a3 and the fifth on-off valve a5 are closed, and the fourth on-off valve a4 is opened to allow natural gas to enter the cooling medium pipeline of the shell and tube heat exchanger 3 for heat exchange;

[0074] When the temperature measured by the second pressure and temperature monitoring device TT2 is greater than or equal to -30°C and less than or equal to 0°C, the third on-off valve a3 and the fourth on-off valve a4 are closed, and the fifth on-off valve a5 and the sixth on-off valve a6 are opened to allow the natural gas to enter the cooling medium pipeline of the shell-and-shell heat exchanger 4 for heat exchange;

[0075] When the temperature measured by the second pressure and temperature monitoring device TT2 is greater than 0° C., the fourth switch valve a4 is closed, and the third switch valve a3 and the fifth switch valve a5 are opened to allow the natural gas to enter the boil-off gas utilization system 13 .

[0076] In some embodiments, the freezer 7 is a temperature-adjustable freezer;

[0077] When the shell and tube heat exchanger 3 is not performing heat exchange, the temperature of the refrigerator 7 is adjusted to the temperature required for compressor cooling, and the eighth switch valve a8 is closed and the seventh switch valve a7 is opened for operation;

[0078] When the shell and tube heat exchanger 3 is performing heat exchange, the seventh switch valve a7 is closed, the eighth switch valve a8 is opened, and the temperature of the refrigerator 7 is interlocked and adjusted with the fifth pressure and temperature monitoring TT5;

[0079] In the shell and tube heat exchanger 3, the refrigerant flows through the shell side and the natural gas flows through the tube side for heat exchange.

[0080] In some embodiments, when the temperature measured by the fourth pressure and temperature monitoring device TT4 is greater than or equal to 5° C., the third switch valve a3 and the fifth switch valve a5 are opened, and the sixth switch valve a6 is closed, and the natural gas enters the boil-off gas utilization system 13;

[0081] When the temperature measured by the fourth pressure and temperature monitoring device TT4 is less than 5°C, the fifth switch valve a5 is closed and the sixth switch valve a6 is opened, and the natural gas enters the cooling medium pipeline of the shell-and-shell heat exchanger 4 for heat exchange;

[0082] When the sixth switch valve a6 is opened, the ninth switch valve a9 is opened and the tenth switch valve a10 is closed;

[0083] When the sixth on-off valve a6 is closed, the ninth on-off valve a9 is closed, and the tenth on-off valve a10 is opened.

[0084] In practical applications, the above technical means can ensure that the atomizing head 10 is not affected in normal use.

[0085] The present invention distributes the cold energy released during the LNG gasification process to hydrogenation pre-cooling, hydrogen compressor cooling circulation, and canopy cooling spray system according to the temperature range of the cold energy, specifically from -120°C to room temperature, to achieve efficient utilization of cold energy. In addition, the present invention includes multiple temperature and pressure detection points. Combined with the actual operating conditions within the station, the cold energy utilization process can be adjusted, which can reduce dependence on external energy sources (such as electricity and fuel) and reduce energy consumption.

[0086] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. Cold energy recovery and utilization system of LNG gasification and hydrogenation combined station; characterized by: It includes a boil-off gas and low-temperature vent gas recovery section (1), a hydrogenator (2), a shell and tube heat exchanger (3) and a jacket heat exchanger (4); The evaporation gas and low-temperature released gas recovery part (1) includes an evaporation gas air-temperature heat exchanger (12) whose air inlet end is connected to the evaporation gas main pipe (11) and whose air outlet end is connected to the evaporation gas utilization system (13); A first pressure and temperature monitoring device (TT1) and a first switch valve (a1) are provided on the pipeline between the evaporation gas main pipe (11) and the evaporation gas air-temperature heat exchanger (12); A second switch valve (a2) is connected between the air inlet end of the first switch valve (a1) and the first pressure and temperature monitoring (TT1) via a three-way connection; The other end of the second on-off valve (a2) is connected in sequence to the coil heat exchanger (5) and the second pressure and temperature monitoring (TT2); The coil heat exchanger (5) is used to pass hydrogen into another pipeline for heat exchange, and the gas outlet is connected to the hydrogenator (2) for supplying hydrogen to the hydrogenator (2); The second pressure and temperature monitoring (TT2) is respectively connected to the fourth switch valve (a4) and the first check valve (b1) through a three-way connection; The other end of the fourth switch valve (a4) is connected to the cooling medium pipeline of the shell and tube heat exchanger (3); The other end of the first check valve (b1) is connected to the third switch valve (a3) ​​and the fifth switch valve (a5) respectively through a three-way connection; The other end of the third switch valve (a3) ​​is connected to the pipeline between the evaporative gas air-temperature heat exchanger (12) and the evaporative gas utilization system (13), and the cooling medium pipeline of the shell-and-shell heat exchanger (4) through a tee. The other end of the fifth switch valve (a5) is connected to the cooling medium pipeline of the shell and tube heat exchanger (3) and the cooling medium pipeline of the jacket heat exchanger (4) through a tee; A fourth pressure and temperature monitor (TT4) is provided between the fifth switch valve (a5) and the shell and tube heat exchanger (3), and a sixth switch valve (a6) is provided between the fifth switch valve (a5) and the jacket-and-sleeve heat exchanger (4).

2. The cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to claim 1 is characterized in that: The cooling medium pipeline of the shell and tube heat exchanger (3) forms a cycle with the hydrogen compressor cooling device (6) and the refrigerator (7) connected in sequence; The inlet of the cooled medium pipeline of the shell and tube heat exchanger (3) is connected to the refrigerant outlet of the refrigerator (7), and an eighth switch valve (a8) is provided on the pipeline therebetween; The outlet of the cooled medium pipeline of the shell and tube heat exchanger (3) is connected to the refrigerant inlet of the hydrogen compressor cooling device (6), and a fifth pressure and temperature monitoring (TT5) is provided on the pipeline therebetween; The pipeline from the refrigerator (7) to the eighth switch valve (a8) and the pipeline from the shell and tube heat exchanger (3) to the fifth pressure and temperature monitoring (TT5) are connected to the seventh switch valve (a7) by respectively setting two three-way connections.

3. The cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to claim 1 is characterized in that: The inlet of the cooled medium pipeline of the jacketed heat exchanger (4) is connected to the domestic water main (8) to obtain domestic water, and a ninth switch valve (a9) is provided between the inlet and the domestic water main (8); The outlet of the cooled medium pipeline of the jacketed heat exchanger (4) is connected to the LNG filling hood and the hydrogenation hood (9), and the pipeline therebetween is provided with a plurality of atomizing bumpers (10) at the portion close to the LNG filling hood and the hydrogenation hood (9); The pipeline from the domestic water main (8) to the ninth switch valve (a9) and the pipeline from the jacketed heat exchanger (4) to the atomizing bumper (10) are connected to the tenth switch valve (a10) by respectively setting two three-way connections.

4. The method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to any one of claims 1 to 3, characterized in that: When there is no hydrogenation operation, the first on-off valve (a1) is opened, the second on-off valve (a2) is closed, and the vented gas is heated by the evaporation gas air-to-air heat exchanger (12) and then enters the evaporation gas utilization system (13) for processing; When hydrogenation is being performed, the first on-off valve (a1) is closed and the second on-off valve (a2) is opened, and the low-temperature boil-off gas is sent out from the second on-off valve (a2).

5. The method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to claim 4 is characterized in that: When the temperature measured by the second pressure and temperature monitoring (TT2) is less than -30°C, the third on-off valve (a3) ​​and the fifth on-off valve (a5) are closed, and the fourth on-off valve (a4) is opened to allow natural gas to enter the cooling medium pipeline of the shell and tube heat exchanger (3) for heat exchange; When the temperature measured by the second pressure and temperature monitoring (TT2) is greater than or equal to -30°C and less than or equal to 0°C, the third on-off valve (a3) ​​and the fourth on-off valve (a4) are closed, and the fifth on-off valve (a5) and the sixth on-off valve (a6) are opened to allow natural gas to enter the cooling medium pipeline of the shell-and-shell heat exchanger (4) for heat exchange; When the temperature measured by the second pressure and temperature monitoring (TT2) is greater than 0°C, the fourth switch valve (a4) is closed, and the third switch valve (a3) ​​and the fifth switch valve (a5) are opened to allow natural gas to enter the boil-off gas utilization system (13).

6. The method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to claim 2 is characterized in that: The freezer (7) is a temperature-adjustable freezer; When the shell and tube heat exchanger (3) is not performing heat exchange, the temperature of the refrigerator (7) is adjusted to the temperature required for compressor cooling, the eighth switch valve (a8) is closed, and the seventh switch valve (a7) is opened for operation; When the shell and tube heat exchanger (3) performs heat exchange, the seventh switch valve (a7) is closed, the eighth switch valve (a8) is opened for operation, and the temperature of the refrigerator (7) is interlocked and regulated with the fifth pressure and temperature monitoring (TT5); In the shell and tube heat exchanger (3), the refrigerant flows through the shell side and the natural gas flows through the tube side for heat exchange.

7. The method for using the cold energy recovery and utilization system of the LNG gasification and hydrogenation combined station according to claim 3 is characterized in that: When the temperature measured by the fourth pressure and temperature monitoring (TT4) is greater than or equal to 5°C, the third on-off valve (a3) ​​and the fifth on-off valve (a5) are opened, and the sixth on-off valve (a6) is closed, so that the natural gas enters the boil-off gas utilization system (13); When the temperature measured by the fourth pressure and temperature monitoring (TT4) is less than 5°C, the fifth switch valve (a5) is closed, the sixth switch valve (a6) is opened, and the natural gas enters the cooling medium pipeline of the shell-and-shell heat exchanger (4) for heat exchange; When the sixth on-off valve (a6) is opened, the ninth on-off valve (a9) is opened, and the tenth on-off valve (a10) is closed; When the sixth on-off valve (a6) is closed, the ninth on-off valve (a9) is closed, and the tenth on-off valve (a10) is opened.

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