Integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation and LNG receiving station

Abstract

The invention discloses a hydrogen liquefaction, liquid hydrogen storage and transportation and LNG receiving station integrated design system and method based on cold energy utilization, and belongs to the technical field of hydrogen liquefaction treatment systems. The system comprises an LNG receiving station, a hydrogen liquefaction treatment system and a liquid hydrogen storage and transportation system. The LNG receiving station comprises an LNG storage tank and a BOG condensation unit, and the BOG condensation unit condenses NG generated in the LNG storage tank into LNG through low-temperature hydrogen generated by the liquid hydrogen storage and transportation system. The hydrogen liquefaction treatment system precools hydrogen through LNG gasification cold energy in the LNG receiving station and the nitrogen refrigeration cycle system, and the nitrogen refrigeration cycle system cools nitrogen through the LNG gasification cold energy. According to the system and method, a large amount of LNG gasification cold energy in the LNG receiving station is fully utilized to achieve hydrogen liquefaction, meanwhile, low-temperature hydrogen generated in the liquid hydrogen storage and transportation system is fully utilized to achieve NG condensation, and therefore LNG and hydrogen energy industry chain optimization matching is achieved, and the investment and operation cost of the LNG receiving station, hydrogen liquefaction and liquid hydrogen storage and transportation factories is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen liquefaction processing systems, and specifically relates to an integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving stations based on cold energy utilization. Background Art

[0002] Under the dual carbon goals, the global hydrogen energy industry is expected to grow rapidly and has huge room for development. The safe and efficient storage and transportation of hydrogen is the key to the hydrogen energy industry. Storing and transporting hydrogen after low-temperature liquefaction will greatly improve the efficiency and safety of hydrogen storage and transportation. However, hydrogen liquefaction is very difficult. During the cooling process, a large amount of conversion heat is released during the conversion of normal and para-hydrogen, further increasing the difficulty of hydrogen refrigeration and liquefaction. Therefore, the energy consumption of hydrogen liquefaction is generally very high. The unit energy consumption of different liquefaction processes is about 12-25kwh / kg. How to reduce the energy consumption of hydrogen liquefaction directly affects the market competitiveness of hydrogen products.

[0003] Based on this, the existing technology needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide an integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving stations based on cold energy utilization, utilizing the cold energy of liquefied natural gas gasification in the LNG receiving station to assist hydrogen liquefaction to reduce the energy consumption of hydrogen liquefaction, and utilizing the low-temperature hydrogen generated in the liquid hydrogen storage and transportation system to assist in condensing LNG evaporated gas in the LNG receiving station to reduce the investment and operating costs of the LNG receiving station, thereby achieving optimal matching of the LNG and hydrogen energy industry chains and reducing the investment and operating costs of LNG receiving stations and hydrogen liquefaction and liquid hydrogen storage and transportation plants.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] According to a first aspect of the present invention, there is provided an integrated design system of hydrogen liquefaction, liquid hydrogen storage and transportation and LNG receiving station based on cold energy utilization, which comprises an LNG receiving station, a hydrogen liquefaction processing system and a liquid hydrogen storage and transportation system, wherein: the LNG receiving station comprises an LNG storage tank and a BOG condensing unit, the BOG condensing unit utilizes the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG evaporated gas generated in the LNG storage tank into liquefied natural gas; the hydrogen liquefaction processing system utilizes the cold energy of liquefied natural gas vaporization in the LNG receiving station and a nitrogen refrigeration cycle system to pre-cool the hydrogen, and the nitrogen refrigeration cycle system utilizes the cold energy of liquefied natural gas vaporization in the LNG receiving station to cool the compressed nitrogen.

[0007] According to some embodiments of the present invention, the LNG receiving station also includes a low-pressure pump inside the LNG tank, a booster pump outside the LNG tank, an LNG gasification unit, and an NG metering and exporting unit which are arranged in sequence, wherein the low-pressure pump inside the LNG tank is used to pressurize the liquefied natural gas in the LNG storage tank to a first pressure, the booster pump outside the LNG tank is used to continue to pressurize the liquefied natural gas at the first pressure to a second pressure, the LNG gasification unit is used to gasify the liquefied natural gas at the second pressure into natural gas, and the NG metering and exporting unit is used to export the natural gas.

[0008] According to some embodiments of the present invention, part of the liquefied natural gas at the second pressure enters the hydrogen liquefaction processing system for precooling the hydrogen, and part enters the nitrogen refrigeration cycle system for cooling the compressed nitrogen.

[0009] According to some embodiments of the present invention, the hydrogen liquefaction processing system includes a raw hydrogen cooling pretreatment unit, a raw hydrogen low-pressure compression unit, a raw hydrogen purification unit, a hydrogen high-pressure compression unit, an LNG precooling unit, a liquid nitrogen precooling unit, a hydrogen deep-cold liquefaction device, and a hydrogen circulating gas compressor, which are arranged in sequence. The raw hydrogen cooling pretreatment unit is used to precool the raw hydrogen, the raw hydrogen low-pressure compression unit is used to pressurize and cool the precooled raw hydrogen, the raw hydrogen purification unit is used to remove impurities from the pressurized and cooled raw hydrogen, and the hydrogen high-pressure compression unit is used to The impurity-removed hydrogen is re-pressurized and cooled, the LNG pre-cooling unit uses the second pressure liquefied natural gas to pre-cool the re-pressurized and cooled hydrogen, the liquid nitrogen pre-cooling unit uses the nitrogen refrigeration cycle system to re-pre-cool the pre-cooled hydrogen, the hydrogen deep-cold liquefaction device is used to liquefy the re-pre-cooled hydrogen, the hydrogen circulating gas compressor is used to pressurize the low-temperature hydrogen circulated from the hydrogen deep-cold liquefaction device and transmit it to the hydrogen high-pressure compression unit, and the liquid hydrogen coming out of the hydrogen deep-cold liquefaction device enters the liquid hydrogen storage and transportation system.

[0010] According to some embodiments of the present invention, after the liquefied natural gas at the second pressure exchanges heat with the re-pressurized and cooled hydrogen at the LNG pre-cooling unit, it enters the hydrogen high-pressure compression unit for heat exchange with the impurity-removed hydrogen, then enters the raw hydrogen low-pressure compression unit for heat exchange with the pre-cooled raw hydrogen, then enters the raw hydrogen cooling and pretreatment unit for heat exchange with the raw hydrogen, and then enters the LNG receiving station to merge with the natural gas obtained after gasification in the LNG gasification unit, and enters the NG metering and transmission unit.

[0011] According to some embodiments of the present invention, the hydrogen high-pressure compression unit includes a hydrogen high-pressure compression unit compressor and a hydrogen high-pressure compression unit heat exchanger which are arranged in sequence, and the liquefied natural gas entering the hydrogen high-pressure compression unit is heat exchanged with the hydrogen compressed by the hydrogen high-pressure compression unit compressor at the hydrogen high-pressure compression unit heat exchanger; the raw hydrogen low-pressure compression unit includes a raw hydrogen low-pressure compression unit compressor and a raw hydrogen low-pressure compression unit heat exchanger, and the liquefied natural gas entering the raw hydrogen low-pressure compression unit is heat exchanged with the hydrogen compressed by the raw hydrogen low-pressure compression unit compressor at the raw hydrogen low-pressure compression unit heat exchanger.

[0012] According to some embodiments of the present invention, the nitrogen refrigeration cycle system includes a nitrogen compressor, a nitrogen heat exchanger, a nitrogen expander or a throttle valve, and a liquid nitrogen separation tank which are arranged in sequence, the nitrogen compressor is used to pressurize the nitrogen, the nitrogen heat exchanger uses the second pressure liquefied natural gas to cool the pressurized nitrogen, the nitrogen expander or the throttle valve is used to cool the cooled nitrogen, the liquid nitrogen separation tank is used to separate liquid nitrogen from unliquefied nitrogen, the separated liquid nitrogen enters the liquid nitrogen precooling unit, and the unliquefied nitrogen enters the nitrogen compressor, the second pressure liquefied natural gas is heat exchanged with the pressurized nitrogen at the nitrogen heat exchanger, and then merges with the liquefied natural gas after heat exchange with the pressurized and cooled hydrogen at the LNG precooling unit, and enters the hydrogen high-pressure compression unit.

[0013] According to some embodiments of the present invention, the liquid hydrogen storage and transportation system also includes a self-pressurizing vaporizer and a liquid hydrogen pump. The liquid hydrogen stored in the liquid hydrogen storage tank is converted into low-temperature hydrogen after heat exchange with the ambient air by the self-pressurizing vaporizer. The liquid hydrogen storage tank is pressurized, and the liquid hydrogen in the liquid hydrogen storage tank is pressed to the inlet of the liquid hydrogen pump. After being pressurized by the liquid hydrogen pump, it is loaded onto a vehicle for external transportation.

[0014] According to some embodiments of the present invention, the low-temperature hydrogen volatilized from the liquid hydrogen storage tank is returned to the hydrogen liquefaction processing system for liquefaction after condensing LNG boil-off gas.

[0015] According to a second aspect of the present invention, there is provided an integrated design method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization, which comprises: in the hydrogen liquefaction process, utilizing the cold energy of liquefied natural gas vaporization in the LNG receiving station and the nitrogen refrigeration cycle system to pre-cool the hydrogen; in the nitrogen refrigeration cycle system, utilizing the cold energy of liquefied natural gas vaporization in the LNG receiving station to cool the compressed nitrogen; in the LNG receiving station, utilizing the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense LNG evaporated gas generated in the LNG storage tank into liquefied natural gas.

[0016] Due to the adoption of the above technical solution, the system and method provided by the present invention have at least one of the following beneficial effects compared with the prior art:

[0017] By using the cold energy of liquefied natural gas in the LNG receiving station to pre-cool the hydrogen during the hydrogen liquefaction process, the temperature of the hydrogen after pre-cooling can be reduced, the effect of hydrogen liquefaction pre-cooling can be improved, and the specific energy consumption of hydrogen liquefaction can be significantly reduced. efficiency;

[0018] By utilizing the cold energy of liquefied natural gas vaporization in the LNG receiving station to cool the compressed nitrogen in the nitrogen refrigeration cycle, the energy consumption and nitrogen refrigeration cycle capacity of the nitrogen refrigeration cycle can be reduced;

[0019] By using the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG boil-off gas in the LNG receiving station, the BOG compressor and recondenser in the LNG receiving station can be omitted, reducing the investment and operating costs of the LNG receiving station. Without being affected by the recondenser, the temperature of the liquefied natural gas after the LNG high-pressure pump can be reduced by about 30°C and is relatively stable;

[0020] By utilizing the cold energy of liquefied natural gas vaporization during the hydrogen liquefaction process to reduce the suction temperature before each compression stage of the hydrogen compressor, the compression efficiency of the hydrogen compressor can be improved.

[0021] The system and method provided by the present invention fully utilize the large amount of LNG gasification cold energy in the LNG receiving station to realize the liquefaction of hydrogen, and at the same time fully utilize the low-temperature hydrogen generated in the liquid hydrogen storage and transportation system to realize the condensation of NG, thereby realizing the optimal matching of the LNG and hydrogen energy industry chains, and reducing the investment and operating costs of the LNG receiving station and the hydrogen liquefaction and liquid hydrogen storage and transportation plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a typical flow chart of an LNG receiving station in the prior art;

[0024] Figure 2 It is a typical flow chart of cold energy utilization of LNG receiving station in the prior art;

[0025] Figure 3 The change of the inlet temperature of the high-pressure pump of the LNG receiving station with the BOG flow rate;

[0026] Figure 4 A schematic diagram of an integrated design system for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization provided by the present invention. DETAILED DESCRIPTION

[0027] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0028] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless specifically defined as in the embodiments of this application.

[0030] As mentioned in the background technology section, safe and efficient storage and transportation of hydrogen is the key to the hydrogen energy industry. Storing and transporting hydrogen after low-temperature liquefaction will greatly improve the efficiency and safety of hydrogen storage and transportation. However, hydrogen liquefaction is very difficult. During the cooling process, a large amount of conversion heat is released during the conversion of normal and para-hydrogen, further increasing the difficulty of hydrogen refrigeration and liquefaction. Therefore, the energy consumption of hydrogen liquefaction is generally very high.

[0031] In the hydrogen liquefaction process, hydrogen is heat-exchanged with other cooling media in a heat exchanger during or after the pressurization process to improve the compressor's pressurization efficiency. Other cooling media include air, cooling water or other refrigerants. Hydrogen liquefaction precooling usually uses liquid nitrogen precooling. High-pressure and low-temperature nitrogen is mainly used in the nitrogen refrigeration cycle. The temperature is further reduced by expansion refrigeration. It exchanges heat with saturated high-pressure nitrogen. The condensed saturated high-pressure nitrogen is further cooled by an expander or a throttle valve to form liquid nitrogen. Other improved hydrogen liquefaction precooling includes mixed refrigerant compression refrigeration type precooling, LNG cold energy utilization type precooling and other precooling schemes. However, the existing LNG cold energy utilization type precooling scheme is usually affected by the recondenser in the LNG receiving station. The temperature of the LNG high-pressure pump after pressurization is high and the temperature is not constant, resulting in a high temperature of the LNG precooled hydrogen, and the hydrogen temperature after precooling is prone to fluctuations, and the precooling effect is not ideal.

[0032] For example, patent document CN 113776275 B discloses a hydrogen liquefaction method under LNG cold energy precooling, which adopts LNG cold energy precooling and nitrogen refrigeration cycle precooling combined with hydrogen multi-stage expansion for efficient hydrogen liquefaction technology. However, this patent document does not improve the LNG used for hydrogen liquefaction. The temperature of LNG used for hydrogen liquefaction is relatively high, and affected by BOG (LNG boil-off gas) at the LNG receiving station, the temperature of LNG used for hydrogen liquefaction is prone to fluctuations, affecting hydrogen liquefaction. Moreover, this patent document mainly optimizes LNG cold energy precooling for the precooling type Claude hydrogen liquefaction cycle.

[0033] BOG treatment at LNG receiving stations usually relies on BOG compressors to pressurize, then heat exchange and mix with supercooled LNG liquid in the recondenser to liquefy, and then enter the high-pressure pump for further pressurization. However, due to the influence of the BOG recondenser, the temperature of LNG after pressurization by the LNG high-pressure pump is high and the temperature is not constant.

[0034] For example, in the article "A new LNG boil-off gas recovery scheme for zero-gas external transport at liquefied natural gas receiving stations" by An Dongyu et al. (Petrochemical Equipment, 2023.52(4):7-11), a typical process of an LNG receiving station is given. Figure 1 As shown in the figure, the LNG receiving station includes LNG storage tanks, low-pressure pumps, LNG high-pressure pumps, LNG vaporizers (SCV, ORV), BOG low-pressure compressors, BOG medium-pressure / high-pressure compressors, and BOG recondensers. The BOG at the LNG receiving station is pressurized by the BOG low-pressure compressor, and then liquefied by heat exchange and mixing with the supercooled LNG liquid provided by the low-pressure pump in the BOG recondenser, and then enters the LNG high-pressure pump for further pressurization.

[0035] For example, in the article "Optimization of BOG Joint Processing Operation Scheme for LNG Receiving Station" by Peng Chao et al. (Oil and Gas Storage and Transportation, 2023, 42(6): 624-631), the typical process of LNG cold energy utilization is introduced, such as Figure 2 As shown. Affected by BOG, the change of high pressure pump inlet temperature is as follows Figure 3 As shown in the figure, it can be seen that due to the influence of the BOG recondenser, the temperature of the LNG after the LNG high-pressure pump is pressurized is high and the temperature is not constant.

[0036] In view of the above situation, the main purpose of the present invention is to provide an integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization, so as to solve at least one of the following technical problems: (1) Solve the problem of high energy consumption of hydrogen liquefaction pre-cooling and unstable LNG pre-cooling temperature; (2) Solve the problem of high energy consumption of hydrogen pressurization before hydrogen liquefaction; (3) Solve the problem of high energy consumption of hydrogen liquefaction nitrogen refrigeration cycle; (4) Solve the problem of high energy consumption of BOG (LNG boil-off gas) treatment at LNG receiving station. The present invention mainly utilizes the cold energy of low-temperature hydrogen volatilized from the liquid hydrogen storage tank to condense the BOG of the LNG receiving station, and utilizes the cold energy of LNG vaporization to pre-cool the hydrogen of the hydrogen liquefaction processing system and to cool the nitrogen of the nitrogen refrigeration cycle.

[0037] According to a first aspect of the present invention, a hydrogen liquefaction, liquid hydrogen storage and transportation and LNG receiving station integrated design system based on cold energy utilization is provided. Figure 4 As shown, the system includes an LNG receiving station, a hydrogen liquefaction processing system, a nitrogen refrigeration cycle processing system and a liquid hydrogen storage and transportation system. The LNG receiving station includes an LNG storage tank 1 and a BOG condensation unit 3. The BOG condensation unit 3 uses the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG boil-off gas generated in the LNG storage tank 1 into liquefied natural gas. The hydrogen liquefaction processing system uses the cold energy of the liquefied natural gas vaporization in the LNG receiving station and the nitrogen refrigeration cycle system to pre-cool the hydrogen, and the nitrogen refrigeration cycle system uses the cold energy of the liquefied natural gas vaporization in the LNG receiving station to cool the compressed nitrogen.

[0038] In the system provided by the present invention, the low-temperature hydrogen generated in the liquid hydrogen storage and transportation system is used to condense the BOG in the LNG receiving station, which can eliminate the BOG compressor and recondenser of the LNG receiving station, thereby reducing the investment and operating costs of the LNG receiving station. After not being affected by the recondenser, the temperature of the LNG after the LNG high-pressure pump can be reduced by about 30°C and is relatively stable. By using the cold energy of LNG vaporization to pre-cool the hydrogen, the temperature of the hydrogen after pre-cooling can be reduced, and the effect of hydrogen liquefaction pre-cooling can be improved. By using the cold energy of LNG vaporization to cool the compressed nitrogen, the energy consumption of the nitrogen refrigeration cycle and the nitrogen refrigeration cycle volume can be reduced. As a result, the system of the present invention can significantly reduce the specific energy consumption of hydrogen liquefaction and improve Efficiency. Taking the pre-cooling Claude hydrogen liquefaction basic process as an example, after using LNG cold energy, the specific energy consumption of hydrogen liquefaction is reduced by 18%. The efficiency is increased by 23%. The system provided by the present invention utilizes low-temperature hydrogen and high-quality cold energy from LNG pressurization and gasification to reduce the investment and operation costs of LNG receiving stations and hydrogen liquefaction plants.

[0039] The LNG receiving station may also include a low-pressure pump 2 in the LNG tank, a booster pump 4 outside the LNG tank, an LNG gasification unit 5, and an NG metering and exporting unit 6, which are arranged in sequence. The low-pressure pump 2 in the LNG tank is used to pressurize the liquefied natural gas in the LNG storage tank 1 to a first pressure. The booster pump 4 outside the LNG tank is used to continue to pressurize the liquefied natural gas at the first pressure to a second pressure. The LNG gasification unit 5 is used to gasify the liquefied natural gas at the second pressure into natural gas. The NG metering and exporting unit 6 is used to export natural gas. A portion of the liquefied natural gas at the second pressure enters the hydrogen liquefaction processing system to pre-cool the hydrogen, and a portion enters the nitrogen refrigeration cycle system to cool the compressed nitrogen. In other words, the low-pressure pump 2 in the LNG tank pressurizes the LNG in the LNG storage tank 1 through the low-pressure pump 2 in the LNG tank and the booster pump 4 outside the LNG tank in sequence, and then gasifies it through the LNG gasification unit 5, and then exports it through the NG metering and exporting unit 5. After being pressurized by the LNG tank external booster pump 4, part of the LNG enters the hydrogen liquefaction processing system to pre-cool the hydrogen, and part of the LNG enters the nitrogen refrigeration cycle system to cool the compressed nitrogen.

[0040] The hydrogen liquefaction processing system includes a raw hydrogen cooling pretreatment unit 7, a raw hydrogen low-pressure compression unit 8, a raw hydrogen purification unit 9, a hydrogen high-pressure compression unit 10, an LNG precooling unit 11, a liquid nitrogen precooling unit 12, a hydrogen deep-cold liquefaction device 13, and a hydrogen circulating gas compressor 14, which are arranged in sequence. The raw hydrogen cooling pretreatment unit 7 is used to precool the raw hydrogen. The raw hydrogen low-pressure compression unit 8 is used to pressurize and cool the precooled raw hydrogen. The raw hydrogen purification unit 9 is used to remove impurities from the pressurized and cooled raw hydrogen. The hydrogen high-pressure compression unit 10 is used to re-pressurize and cool the impurity-removed hydrogen, and the LNG precooling unit 11 uses liquefied natural gas at a second pressure to precool the re-pressurized and cooled hydrogen. The liquid nitrogen precooling unit 12 uses a nitrogen refrigeration cycle system to re-precool the precooled hydrogen. The hydrogen deep-cold liquefaction device 13 is used to liquefy the re-precooled hydrogen. The hydrogen circulating gas compressor 14 is used to pressurize the low-temperature hydrogen circulated from the hydrogen cryogenic liquefaction device 13 and transmit it to the hydrogen high-pressure compression unit 10. The liquid hydrogen from the hydrogen cryogenic liquefaction device 13 enters the liquid hydrogen storage and transportation system. That is, the raw hydrogen is precooled by the raw hydrogen cooling pretreatment unit 7 and pressurized and cooled by the raw hydrogen low-pressure compression unit 8, and then enters the raw hydrogen purification unit 9 for impurity removal. The impurity-removed hydrogen is pressurized and cooled by the hydrogen high-pressure compression unit 10 again, and then enters the LNG precooling unit 11 and the liquid nitrogen precooling unit 12 for precooling in sequence, and then enters the hydrogen cryogenic liquefaction device 13 for liquefaction. The liquid hydrogen obtained by liquefaction enters the liquid hydrogen storage and transportation system for storage and transportation. The low-temperature hydrogen circulated from the hydrogen cryogenic liquefaction device 13 enters the LNG precooling unit 11 of the hydrogen liquefaction treatment system for heat exchange. The hydrogen after heat exchange is pressurized by the hydrogen circulating gas compressor 14 and merged into the hydrogen at the inlet of the hydrogen high-pressure compression unit. After the liquefied natural gas at the second pressure exchanges heat with the repressurized and cooled hydrogen at the LNG precooling unit 11, it enters the hydrogen high-pressure compression unit 10 to exchange heat with the impurity-removed hydrogen, then enters the raw hydrogen low-pressure compression unit 8 to exchange heat with the precooled raw hydrogen, then enters the raw hydrogen cooling pretreatment unit 7 to exchange heat with the raw hydrogen, then enters the LNG receiving station, merges with the natural gas obtained after gasification in the LNG gasification unit 5, and enters the NG metering and external transmission unit 6. The LNG gasification cold energy can be used to reduce the suction temperature before each compression stage of the hydrogen compressor and improve the compression efficiency of the hydrogen compressor.

[0041] The hydrogen liquefaction process of the hydrogen deep-cold liquefaction device 13 includes but is not limited to the pre-cooling Linde-Hampson hydrogen liquefaction process, the pre-cooling Claude cycle hydrogen liquefaction process, the pre-cooling helium expansion hydrogen liquefaction process or any one of the improved versions of the three basic hydrogen liquefaction processes.

[0042] The hydrogen high-pressure compression unit 10 includes a hydrogen high-pressure compression unit compressor 10-1 and a hydrogen high-pressure compression unit heat exchanger 10-2, which are arranged in sequence. The liquefied natural gas entering the hydrogen high-pressure compression unit 10 exchanges heat with the hydrogen compressed by the hydrogen high-pressure compression unit compressor 10-1 at the hydrogen high-pressure compression unit heat exchanger 10-2. The raw hydrogen low-pressure compression unit 8 includes a raw hydrogen low-pressure compression unit compressor 8-1 and a raw hydrogen low-pressure compression unit heat exchanger 8-2. The liquefied natural gas entering the raw hydrogen low-pressure compression unit 8 exchanges heat with the hydrogen compressed by the raw hydrogen low-pressure compression unit compressor 8-1 at the raw hydrogen low-pressure compression unit heat exchanger 8-2.

[0043] The nitrogen refrigeration cycle system includes a nitrogen compressor 18, a nitrogen heat exchanger 19, a nitrogen expander or a throttle valve 20, and a liquid nitrogen separation tank 21, which are arranged in sequence. The nitrogen compressor 18 is used to pressurize the nitrogen. The nitrogen heat exchanger 19 uses the liquefied natural gas at the second pressure to cool the pressurized nitrogen. The nitrogen expander or the throttle valve 20 is used to cool the cooled nitrogen. The liquid nitrogen separation tank 21 is used to separate liquid nitrogen from unliquefied nitrogen. The separated liquid nitrogen enters the liquid nitrogen precooling unit 12, and the unliquefied nitrogen enters the nitrogen compressor 18. After the liquefied natural gas at the second pressure exchanges heat with the pressurized nitrogen at the nitrogen heat exchanger 19, it merges with the liquefied natural gas after heat exchange with the pressurized and cooled hydrogen at the LNG precooling unit 11, and enters the hydrogen high-pressure compression unit 10. That is to say, the nitrogen pressurized by the nitrogen compressor 18 enters the nitrogen heat exchanger 19, and then is cooled by the nitrogen expander or the throttle valve 20, and the liquid nitrogen is separated by the liquid nitrogen separation tank 21. The unliquefied nitrogen is re-integrated into the inlet of the nitrogen compressor 18, and the liquid nitrogen enters the liquid nitrogen precooling unit 12 of the hydrogen liquefaction treatment system to precool the hydrogen. A part of the LNG pressurized by the booster pump 4 outside the LNG tank enters the nitrogen heat exchanger 19 for heat exchange with the nitrogen, and the LNG after heat exchange with the nitrogen and the LNG after heat exchange with the hydrogen are combined and enter the hydrogen high-pressure compression unit heat exchanger 10-2.

[0044] The liquid hydrogen storage and transportation system includes a liquid hydrogen storage tank 15, a self-pressurizing vaporizer 16 and a liquid hydrogen pump 17. The liquid hydrogen stored in the liquid hydrogen storage tank 15 is converted into low-temperature hydrogen after heat exchange with ambient air by the self-pressurizing vaporizer 16, and the liquid hydrogen in the liquid hydrogen storage tank 15 is pressurized to the inlet of the liquid hydrogen pump 17, and is loaded and transported after being pressurized by the liquid hydrogen pump 17. The low-temperature hydrogen volatilized from the liquid hydrogen storage tank 15 is returned to the hydrogen liquefaction processing system for liquefaction after condensing the LNG evaporated gas.

[0045] An embodiment of the present invention is described in detail below.

[0046] Low-temperature hydrogen LNG boil-off gas is drawn out from the liquid hydrogen storage tank 15, with a temperature of about -250℃~-200℃ and a pressure of about 50kPag~200kPag, and transported to the top of the LNG storage tank 1, and enters the BOG condensation unit 3, where the cold energy of the low-temperature hydrogen is used to exchange heat with the BOG, so that the BOG is condensed into LNG at about -160℃, and then flows back to the LNG storage tank 1 by gravity.

[0047] After the LNG at about -162℃ in the LNG storage tank 1 is pressurized to 0.7MPag~1.2MPag by the low-pressure pump 2 in the LNG tank, part of it goes to the LNG loading and cold preservation circulation system, and the rest enters the booster pump 4 outside the LNG tank to be pressurized to the pressure required for NG external transmission, which is generally 6.0MPag~10.5MPag. Since it is not affected by BOG recondensation, the outlet temperature of the booster pump 4 outside the LNG tank is relatively stable, and the temperature is generally -160℃~-158℃. Then part of it is gasified to above 0℃ by the gasifier of the LNG gasification unit 5, and part of it goes to the hydrogen liquefaction system and the nitrogen refrigeration circulation system for LNG gasification cold energy utilization. The NG gasified by the LNG gasification unit 5 and the NG after LNG gasification cold energy utilization are combined, and the NG is externally transmitted after the metering external transmission unit 6.

[0048] Part of the LNG used for LNG gasification cold energy goes to the LNG precooling unit of the hydrogen liquefaction system to precool the hydrogen to -159°C ~ -157°C. After heat exchange, the LNG enters the hydrogen high-pressure compression unit 10 to exchange heat with the compressed hydrogen, and then enters the raw hydrogen low-pressure compression unit 8 to exchange heat with the compressed hydrogen, and finally enters the raw hydrogen cooling pretreatment unit 7 to reheat the raw gas to above 0°C, and then returns to the NG metering and external transmission unit 6. Part of the LNG that is used for LNG gasification cold energy is sent to the nitrogen heat exchanger 19 of the nitrogen refrigeration cycle system, and the N2 pressurized by the nitrogen compressor 18 is cooled to -159°C ~ -157°C, and then cooled to about -192~-195°C through the nitrogen expander or the throttle valve 20, and LN2 is separated through the liquid nitrogen separation tank 21. The unliquefied N2 gas is re-integrated into the inlet of the nitrogen compressor 18, and the liquefied LN2 enters the liquid nitrogen precooling unit 12 of the hydrogen liquefaction treatment system to precool the hydrogen to about 77K~80K. The N2 after heat exchange and gasification is circulated to the inlet of the nitrogen compressor 18 of the nitrogen refrigeration cycle.

[0049] The qualified raw hydrogen passes through the raw hydrogen cooling pretreatment unit 7, is gasified and NG precooled, and after being pressurized and cooled by the raw hydrogen low-pressure compression unit 8, enters the raw hydrogen purification unit 9 to remove impurities, and the purified hydrogen is pressurized and cooled by the hydrogen high-pressure compression unit 10. The pressurized hydrogen is precooled to about 77K~80K by the LNG precooling unit 11 and the liquid nitrogen precooling unit respectively. The hydrogen flow channel of the heat exchanger of the LNG precooling unit and the liquid nitrogen precooling unit is filled with a normal para-hydrogen conversion catalyst to achieve continuous catalytic conversion of normal para-hydrogen at the precooling temperature. The hydrogen after the normal para-hydrogen conversion equilibrium enters the hydrogen deep-cold liquefaction device for liquefaction. The 20K LH2 from the hydrogen deep-cold liquefaction device enters the liquid hydrogen storage tank 15 for storage, and the low-temperature hydrogen (if any) circulated from the hydrogen deep-cold liquefaction device 13 enters the LNG precooling unit 11 of the hydrogen liquefaction treatment system for heat exchange. The hydrogen after heat exchange is pressurized by the hydrogen circulating gas compressor 14 and merged into the hydrogen at the inlet of the hydrogen high-pressure compression unit 10.

[0050] The LH2 stored in the liquid hydrogen storage tank is converted into low-temperature hydrogen after heat exchange with ambient air by the self-pressurizing vaporizer 16, and the liquid hydrogen storage tank 15 is pressurized, and the LH2 in the liquid hydrogen storage tank 15 is pressed to the inlet of the LH2 pump 17, and loaded and transported after pressurization by the LH2 pump 17. The low-temperature hydrogen volatilized from the liquid hydrogen storage tank 15 goes to the BOG condensing unit 3 on the top of the LNG storage tank 1, and exchanges heat with BOG. ​​The hydrogen after heat exchange is returned to the inlet of the hydrogen circulating gas compressor 14 of the hydrogen liquefaction processing system.

[0051] According to the second aspect of the present invention, a method for integrated design of hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization is provided. The method comprises: in the process of hydrogen liquefaction, precooling the hydrogen by utilizing the cold energy of liquefied natural gas gasification in the LNG receiving station and the nitrogen refrigeration cycle, and in the nitrogen refrigeration cycle system, cooling the compressed nitrogen by utilizing the cold energy of liquefied natural gas gasification in the LNG receiving station; in the LNG receiving station, condensing the LNG evaporation gas generated in the LNG storage tank into liquefied natural gas by utilizing the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system. It should be understood that, in the absence of mutual conflict, all the embodiments, features and advantages described above for the integrated design system of hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization according to the first aspect of the present invention are also applicable to the integrated design method of hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization according to the second aspect of the present invention. That is to say, all the embodiments and their variations described above can be directly transferred and applied and combined here. For the sake of brevity of the present disclosure, they will not be repeated here.

[0052] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0054] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An integrated design system for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving station based on cold energy utilization, characterized in that: It includes LNG receiving station, hydrogen liquefaction processing system and liquid hydrogen storage and transportation system, including: The LNG receiving station includes an LNG storage tank and a BOG condensing unit, wherein the BOG condensing unit utilizes the low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG boil-off gas generated in the LNG storage tank into liquefied natural gas; The hydrogen liquefaction processing system utilizes the cold energy of liquefied natural gas vaporization in the LNG receiving station and the nitrogen refrigeration cycle system to pre-cool the hydrogen, and the nitrogen refrigeration cycle system utilizes the cold energy of liquefied natural gas vaporization in the LNG receiving station to cool the compressed nitrogen.

2. The system according to claim 1, characterized in that The LNG receiving station also includes a low-pressure pump inside the LNG tank, a booster pump outside the LNG tank, an LNG gasification unit, and an NG metering and exporting unit which are arranged in sequence. The low-pressure pump inside the LNG tank is used to pressurize the liquefied natural gas in the LNG storage tank to a first pressure, the booster pump outside the LNG tank is used to continue to pressurize the liquefied natural gas at the first pressure to a second pressure, the LNG gasification unit is used to gasify the liquefied natural gas at the second pressure into natural gas, and the NG metering and exporting unit is used to export the natural gas.

3. The system according to claim 2, characterized in that A portion of the liquefied natural gas at the second pressure enters the hydrogen liquefaction processing system for precooling the hydrogen, and a portion enters the nitrogen refrigeration cycle system for cooling the compressed nitrogen.

4. The system according to claim 3, characterized in that The hydrogen liquefaction processing system comprises a raw hydrogen cooling pretreatment unit, a raw hydrogen low-pressure compression unit, a raw hydrogen purification unit, a hydrogen high-pressure compression unit, an LNG precooling unit, a liquid nitrogen precooling unit, a hydrogen deep-cold liquefaction device, and a hydrogen circulating gas compressor, which are arranged in sequence. The raw hydrogen cooling pretreatment unit is used to precool the raw hydrogen, the raw hydrogen low-pressure compression unit is used to pressurize and cool the precooled raw hydrogen, the raw hydrogen purification unit is used to remove impurities from the pressurized and cooled raw hydrogen, and the hydrogen high-pressure compression unit is used to pressurize and cool the impurity-free hydrogen. Re-pressurization and cooling are performed, the LNG pre-cooling unit uses the liquefied natural gas at the second pressure to pre-cool the hydrogen that has been re-pressurized and cooled, the liquid nitrogen pre-cooling unit uses the nitrogen refrigeration cycle system to re-pre-cool the pre-cooled hydrogen, the hydrogen deep-cold liquefaction device is used to liquefy the re-pre-cooled hydrogen, the hydrogen circulating gas compressor is used to pressurize the low-temperature hydrogen circulated from the hydrogen deep-cold liquefaction device and transmit it to the hydrogen high-pressure compression unit, and the liquid hydrogen coming out of the hydrogen deep-cold liquefaction device enters the liquid hydrogen storage and transportation system.

5. The system according to claim 4, characterized in that After the liquefied natural gas at the second pressure exchanges heat with the re-pressurized and cooled hydrogen at the LNG pre-cooling unit, it enters the hydrogen high-pressure compression unit to exchange heat with the impurity-removed hydrogen, then enters the raw hydrogen low-pressure compression unit to exchange heat with the pre-cooled raw hydrogen, then enters the raw hydrogen cooling and pretreatment unit to exchange heat with the raw hydrogen, and then enters the LNG receiving station to merge with the natural gas obtained after gasification in the LNG gasification unit, and enters the NG metering and transmission unit.

6. The system according to claim 4, characterized in that The hydrogen high-pressure compression unit includes a hydrogen high-pressure compression unit compressor and a hydrogen high-pressure compression unit heat exchanger which are arranged in sequence, and the liquefied natural gas entering the hydrogen high-pressure compression unit exchanges heat with the hydrogen compressed by the hydrogen high-pressure compression unit compressor at the hydrogen high-pressure compression unit heat exchanger; the raw hydrogen low-pressure compression unit includes a raw hydrogen low-pressure compression unit compressor and a raw hydrogen low-pressure compression unit heat exchanger, and the liquefied natural gas entering the raw hydrogen low-pressure compression unit exchanges heat with the hydrogen compressed by the raw hydrogen low-pressure compression unit compressor at the raw hydrogen low-pressure compression unit heat exchanger.

7. The system according to claim 5, characterized in that The nitrogen refrigeration cycle system comprises a nitrogen compressor, a nitrogen heat exchanger, a nitrogen expander or a throttle valve, and a liquid nitrogen separation tank which are arranged in sequence. The nitrogen compressor is used to pressurize the nitrogen. The nitrogen heat exchanger uses the liquefied natural gas at the second pressure to cool the pressurized nitrogen. The nitrogen expander or the throttle valve is used to cool the cooled nitrogen. The liquid nitrogen separation tank is used to separate liquid nitrogen from unliquefied nitrogen. The separated liquid nitrogen enters the liquid nitrogen precooling unit, and the unliquefied nitrogen enters the nitrogen compressor. The liquefied natural gas at the second pressure exchanges heat with the pressurized nitrogen at the nitrogen heat exchanger, and then merges with the liquefied natural gas after heat exchange with the pressurized and cooled hydrogen at the LNG precooling unit, and enters the hydrogen high-pressure compression unit.

8. The system according to claim 1, characterized in that The liquid hydrogen storage and transportation system also includes a self-pressurizing vaporizer and a liquid hydrogen pump. The liquid hydrogen stored in the liquid hydrogen storage tank is converted into low-temperature hydrogen after heat exchange with ambient air by the self-pressurizing vaporizer. The liquid hydrogen storage tank is pressurized and the liquid hydrogen in the liquid hydrogen storage tank is pressed to the inlet of the liquid hydrogen pump. After being pressurized by the liquid hydrogen pump, it is loaded onto a vehicle for external transportation.

9. The system according to claim 1, characterized in that The low-temperature hydrogen volatilized from the liquid hydrogen storage tank is returned to the hydrogen liquefaction processing system for liquefaction after condensing the LNG evaporated gas.

10. A method for integrated design of hydrogen liquefaction, liquid hydrogen storage and transportation and LNG receiving station based on cold energy utilization, characterized in that: include: In the hydrogen liquefaction process, the hydrogen is precooled by using the cold energy of liquefied natural gas vaporization in the LNG receiving station and the nitrogen refrigeration cycle system, and in the nitrogen refrigeration cycle system, the compressed nitrogen is cooled by using the cold energy of liquefied natural gas vaporization in the LNG receiving station; In the LNG receiving station, the low-temperature hydrogen produced by the liquid hydrogen storage and transportation system is used to condense the LNG boil-off gas produced in the LNG storage tank into liquefied natural gas.

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