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

Abstract

The application 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 condensing unit, the BOG condensing unit uses low-temperature hydrogen generated by the liquid hydrogen storage and transportation system to condense NG generated in the LNG storage tank into LNG. The hydrogen liquefaction treatment system uses LNG gasification cold energy in the LNG receiving station and a nitrogen refrigeration circulating system to precool hydrogen, and the nitrogen refrigeration circulating system uses the LNG gasification cold energy to cool nitrogen. The system and method provided by the application fully utilize a large amount of LNG gasification cold energy in the LNG receiving station to realize hydrogen liquefaction, and fully utilize low-temperature hydrogen generated in the liquid hydrogen storage and transportation system to realize NG condensation, thereby realizing optimized matching of LNG and hydrogen energy industrial chains, and reducing investment and operation costs of the LNG receiving station and hydrogen liquefaction and liquid hydrogen storage and transportation plants.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrogen liquefaction processing systems, specifically relating 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 Technology

[0002] Under the dual carbon targets, the global hydrogen energy industry is expected to grow rapidly with huge development potential. The safe and efficient storage and transportation of hydrogen is the key to the hydrogen energy industry. The storage and transportation of hydrogen after cryogenic liquefaction will greatly improve the efficiency and safety of hydrogen storage and transportation. However, hydrogen liquefaction is very difficult. During the cooling process, the conversion of positive and negative hydrogen releases a large amount of conversion heat, which further increases 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 12-25 kWh / kg. How to reduce the energy consumption of hydrogen liquefaction directly affects the market competitiveness of hydrogen products.

[0003] Therefore, existing technologies need to be improved. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization. This system utilizes the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal to assist hydrogen liquefaction, thereby reducing energy consumption. It also utilizes the low-temperature hydrogen generated in the liquid hydrogen storage and transportation system to assist in the condensation of LNG vapors in the LNG receiving terminal, thus reducing investment and operating costs. This achieves optimized matching of the LNG and hydrogen energy industry chains, reducing investment and operating costs for LNG receiving terminals, hydrogen liquefaction, and liquid hydrogen storage and transportation plants.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] According to a first aspect of the present invention, an integrated design system for hydrogen liquefaction, liquid hydrogen storage and transportation, and an LNG receiving terminal based on cold energy utilization is provided. This system includes an LNG receiving terminal, a hydrogen liquefaction processing system, and a liquid hydrogen storage and transportation system. The LNG receiving terminal includes an LNG storage tank and a BOG condensation unit. The BOG condensation unit utilizes the cryogenic hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG vaporized gas generated in the LNG storage tank into liquefied natural gas. The hydrogen liquefaction processing system utilizes the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal and a nitrogen refrigeration cycle system to pre-cool the hydrogen. The nitrogen refrigeration cycle system utilizes the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal to cool the compressed nitrogen.

[0007] According to some embodiments of the present invention, the LNG receiving terminal further includes, in sequence, an in-tank low-pressure pump, an external LNG booster pump, an LNG vaporization unit, and an NG metering and export unit. The in-tank low-pressure pump is used to pressurize the liquefied natural gas in the LNG storage tank to a first pressure. The external LNG booster pump is used to further pressurize the liquefied natural gas at the first pressure to a second pressure. The LNG vaporization unit is used to vaporize the liquefied natural gas at the second pressure into natural gas. The NG metering and export unit is used to export natural gas.

[0008] According to some embodiments of the present invention, 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.

[0009] According to some embodiments of the present invention, the hydrogen liquefaction system includes, in sequence, a raw material hydrogen cooling pretreatment unit, a raw material hydrogen low-pressure compression unit, a raw material hydrogen purification unit, a hydrogen high-pressure compression unit, an LNG precooling unit, a liquid nitrogen precooling unit, a hydrogen cryogenic liquefaction device, and a hydrogen circulating gas compressor. The raw material hydrogen cooling pretreatment unit is used to precool the raw material hydrogen; the raw material hydrogen low-pressure compression unit is used to pressurize and cool the precooled raw material hydrogen; the raw material hydrogen purification unit is used to remove impurities from the pressurized and cooled raw material hydrogen; and the hydrogen high-pressure compression unit is used to... The purified hydrogen is repressurized and cooled. The LNG precooling unit uses liquefied natural gas at the second pressure to precool the repressurized and cooled hydrogen. The liquid nitrogen precooling unit uses the nitrogen refrigeration cycle system to re-precool the precooled hydrogen. The hydrogen cryogenic liquefaction device is used to liquefy the re-precooled hydrogen. The hydrogen circulating gas compressor is used to pressurize the low-temperature hydrogen circulating from the hydrogen cryogenic liquefaction device and transfer it to the hydrogen high-pressure compression unit. The liquid hydrogen from the hydrogen cryogenic liquefaction device enters the liquid hydrogen storage and transportation system.

[0010] According to some embodiments of the present invention, the liquefied natural gas at the second pressure exchanges heat with repressurized and cooled hydrogen at the LNG precooling unit, then enters the hydrogen high-pressure compression unit to exchange heat with purified hydrogen, then enters the feedstock hydrogen low-pressure compression unit to exchange heat with precooled feedstock hydrogen, then enters the feedstock hydrogen cooling pretreatment unit to exchange heat with feedstock hydrogen, and then enters the LNG receiving station to merge with the natural gas obtained after gasification in the LNG gasification unit, and then enters the NG metering and export unit.

[0011] According to some embodiments of the present invention, the high-pressure hydrogen compression unit includes a high-pressure hydrogen compression unit compressor and a high-pressure hydrogen compression unit heat exchanger arranged sequentially. The liquefied natural gas entering the high-pressure hydrogen compression unit exchanges heat with the hydrogen compressed by the high-pressure hydrogen compression unit compressor at the high-pressure hydrogen compression unit heat exchanger. The low-pressure feedstock hydrogen compression unit includes a low-pressure feedstock hydrogen compression unit compressor and a low-pressure feedstock hydrogen compression unit heat exchanger. The liquefied natural gas entering the low-pressure feedstock hydrogen compression unit exchanges heat with the hydrogen compressed by the low-pressure feedstock hydrogen compression unit compressor at the low-pressure feedstock hydrogen 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 throttle valve, and a liquid nitrogen separator arranged in sequence. The nitrogen compressor is used to pressurize nitrogen. The nitrogen heat exchanger uses liquefied natural gas at the second pressure to cool the pressurized nitrogen. The nitrogen expander or throttle valve is used to cool the cooled nitrogen. The liquid nitrogen separator 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 exchanging heat with 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 further includes a self-pressurizing vaporizer and a liquid hydrogen pump. The liquid hydrogen stored in the liquid hydrogen storage tank is converted into cryogenic hydrogen gas after heat exchange with the ambient air through the self-pressurizing vaporizer, which pressurizes the liquid hydrogen storage tank and pushes the liquid hydrogen in the liquid hydrogen storage tank to the inlet of the liquid hydrogen pump. After being pressurized by the liquid hydrogen pump, it is loaded onto vehicles for external transportation.

[0014] According to some embodiments of the present invention, the cryogenic hydrogen gas volatilized from the liquid hydrogen storage tank is returned to the hydrogen liquefaction treatment system for liquefaction after condensing the LNG vapor gas.

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

[0016] Due to the adoption of the above technical solutions, 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 utilizing the vaporization cooling energy of liquefied natural gas in the LNG receiving terminal to pre-cool the hydrogen during the hydrogen liquefaction process, the temperature of the pre-cooled hydrogen can be reduced, improving the pre-cooling effect of hydrogen liquefaction, significantly reducing the specific energy consumption of hydrogen liquefaction, and increasing efficiency. efficiency;

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

[0019] By using the cryogenic hydrogen generated by the liquid hydrogen storage and transportation system to condense the LNG vapor gas in the LNG receiving terminal, the BOG compressor and recondenser in the LNG receiving terminal can be eliminated, reducing the investment and operating costs of the LNG receiving terminal. Without the influence of the recondenser, the temperature of the liquefied natural gas after the LNG high-pressure pump can be reduced by about 30°C and become relatively stable.

[0020] By utilizing the cold energy from the vaporization of liquefied natural gas during the hydrogen liquefaction process to reduce the intake 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 this invention make full use of the large amount of LNG vaporization cold energy in LNG receiving terminals to achieve hydrogen liquefaction, and at the same time make full use of the low-temperature hydrogen generated in the liquid hydrogen storage and transportation system to achieve NG condensation. This achieves optimized matching of the LNG and hydrogen energy industry chain and reduces the investment and operating costs of LNG receiving terminals, hydrogen liquefaction, and liquid hydrogen storage and transportation plants. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a typical flowchart of an LNG receiving terminal in the prior art;

[0024] Figure 2 This is a typical flowchart of cold energy utilization in existing LNG receiving terminals;

[0025] Figure 3 The variation of BOG flow rate with the inlet temperature of the high-pressure pump at the LNG receiving terminal.

[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 Implementation

[0027] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

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

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. 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 should not be interpreted in an idealized or overly formal sense unless specifically defined as in the embodiments of this application.

[0030] As described in the background section, the safe and efficient storage and transportation of hydrogen is crucial to the hydrogen energy industry. The storage and transportation of hydrogen after cryogenic liquefaction will greatly improve the efficiency and safety of hydrogen storage and transportation. However, hydrogen liquefaction is very difficult. During the cooling process, the conversion of positive and negative hydrogen releases a large amount of heat of conversion, which further increases the difficulty of hydrogen refrigeration and liquefaction. Therefore, the energy consumption for hydrogen liquefaction is generally very high.

[0031] In hydrogen liquefaction, hydrogen undergoes heat exchange with other cooling media in a heat exchanger during or after pressurization to improve compressor efficiency. Other cooling media include air, cooling water, or other refrigerants. Hydrogen liquefaction precooling typically uses liquid nitrogen. The nitrogen refrigeration cycle primarily utilizes high-pressure, low-temperature nitrogen, which is further cooled through expansion refrigeration. It exchanges heat with saturated high-pressure nitrogen, and the condensed saturated high-pressure nitrogen is further cooled by an expander or throttling valve to form liquid nitrogen. Other improved hydrogen liquefaction precooling methods include mixed refrigerant compression refrigeration and LNG cold energy utilization precooling. However, current LNG cold energy utilization precooling methods are often affected by the recondenser in the LNG receiving terminal. The high and unstable temperature of the LNG after pressurization by the high-pressure pump leads to a higher temperature of the precooled hydrogen, and the hydrogen temperature fluctuates easily after precooling, resulting in unsatisfactory precooling effects.

[0032] For example, patent document CN 113776275 B discloses a hydrogen liquefaction method under LNG cold energy precooling, employing a high-efficiency hydrogen liquefaction technology that combines LNG cold energy precooling and nitrogen refrigeration cycle precooling with multi-stage hydrogen expansion. However, this patent document does not improve the LNG used for hydrogen liquefaction. The LNG used for hydrogen liquefaction has a relatively high temperature, and its temperature is easily fluctuated due to the influence of BOG (LNG evaporation gas) at the LNG receiving terminal, affecting hydrogen liquefaction. Furthermore, this patent document mainly focuses on optimizing LNG cold energy precooling for a precooled Claude hydrogen liquefaction cycle.

[0033] LNG receiving terminals typically handle BOG (Boiled Air Gathering) by pressurizing it with a BOG compressor, then liquefying it by heat exchange with subcooled LNG in a recondenser before it enters a high-pressure pump for further pressurization. However, due to the influence of the BOG recondenser, the temperature of the LNG pressurized by the high-pressure pump is relatively high and not constant.

[0034] For example, the article "A Novel LNG Evaporation Gas Recovery Scheme for Zero-Gaseous Export from Liquefied Natural Gas Receiving Terminals" by An Dongyu et al. (Petrochemical Equipment, 2023, 52(4): 7-11) presents a typical process for LNG receiving terminals. Figure 1 As shown, the LNG receiving terminal includes LNG storage tanks, low-pressure pumps, LNG high-pressure pumps, LNG vaporizers (SCV, ORV), BOG low-pressure compressors, BOG medium / high-pressure compressors, and BOG recondensers. The BOG in the LNG receiving terminal is pressurized by the BOG low-pressure compressors, then liquefied in the BOG recondenser after heat exchange and mixing with subcooled LNG supplied by the low-pressure pumps. It then enters the LNG high-pressure pumps for further pressurization.

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

[0036] In view of the above situation, the main purpose of this invention is to provide an integrated design system and method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization, so as to solve at least one of the following technical problems: (1) solving the problems of high energy consumption for hydrogen liquefaction precooling and unstable LNG precooling temperature; (2) solving the problem of high energy consumption for hydrogen pressurization before hydrogen liquefaction; (3) solving the problem of high energy consumption for the nitrogen refrigeration cycle of hydrogen liquefaction; (4) solving the problem of high energy consumption for BOG (LNG vaporized gas) processing in LNG receiving terminals. This invention mainly utilizes the cold energy of low-temperature hydrogen volatilized from liquid hydrogen storage tanks to condense the BOG in LNG receiving terminals, and utilizes the cold energy of LNG vaporization to precool the hydrogen in the hydrogen liquefaction processing system and to cool the nitrogen in the nitrogen refrigeration cycle.

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

[0038] The system provided by this invention utilizes cryogenic hydrogen generated in the liquid hydrogen storage and transportation system to condense BOG (Boiled Gas) in the LNG receiving terminal, eliminating the need for BOG compressors and recondensers, thus reducing investment and operating costs. Without the recondenser, the LNG temperature after the high-pressure pump can be reduced by approximately 30°C and remains relatively stable. Using the cold energy from LNG vaporization to pre-cool hydrogen lowers its temperature and improves the pre-cooling effect of hydrogen liquefaction. Utilizing the cold energy from LNG vaporization to cool compressed nitrogen reduces the energy consumption and flow rate of the nitrogen refrigeration cycle. Therefore, the system of this invention can significantly reduce the specific energy consumption of hydrogen liquefaction and improve... Efficiency. Taking the pre-cooled Claude hydrogen liquefaction basic process as an example, by utilizing LNG cold energy, the energy consumption of hydrogen liquefaction is reduced by 18%. Efficiency is improved by 23%. The system provided by this invention utilizes the high-grade cold energy from the pressurized gasification of cryogenic hydrogen and LNG, while reducing the investment and operating costs of LNG receiving terminals and hydrogen liquefaction plants.

[0039] The LNG receiving terminal may also include, in sequence, an in-tank low-pressure pump 2, an external LNG booster pump 4, an LNG vaporization unit 5, and an NG metering and export unit 6. The in-tank low-pressure pump 2 pressurizes the liquefied natural gas (LNG) in the LNG storage tank 1 to a first pressure. The external LNG booster pump 4 further pressurizes the LNG at the first pressure to a second pressure. The LNG vaporization unit 5 vaporizes the LNG at the second pressure into natural gas. The NG metering and export unit 6 exports the natural gas. A portion of the LNG at the second pressure enters the hydrogen liquefaction system for pre-cooling hydrogen, and another portion enters the nitrogen refrigeration cycle system for cooling the compressed nitrogen. In other words, the in-tank low-pressure pump 2 pressurizes the LNG in the LNG storage tank 1 sequentially through the in-tank low-pressure pump 2 and the external LNG booster pump 4, then vaporizes it through the LNG vaporization unit 5, and finally exports it through the NG metering and export unit 5. After being pressurized by the external booster pump 4, part of the LNG enters the hydrogen liquefaction system to pre-cool the hydrogen, and part enters the nitrogen refrigeration cycle system to cool the compressed nitrogen.

[0040] The hydrogen liquefaction system includes, in sequence, a raw material hydrogen cooling pretreatment unit 7, a raw material hydrogen low-pressure compression unit 8, a raw material hydrogen purification unit 9, a hydrogen high-pressure compression unit 10, an LNG precooling unit 11, a liquid nitrogen precooling unit 12, a hydrogen cryogenic liquefaction device 13, and a hydrogen circulating gas compressor 14. The raw material hydrogen cooling pretreatment unit 7 is used to precool the raw material hydrogen. The raw material hydrogen low-pressure compression unit 8 is used to pressurize and cool the precooled raw material hydrogen. The raw material hydrogen purification unit 9 is used to remove impurities from the pressurized and cooled raw material hydrogen. The hydrogen high-pressure compression unit 10 is used to repressurize and cool the impurity-removed hydrogen. The LNG precooling unit 11 uses liquefied natural gas at a second pressure to precool the repressurized and cooled hydrogen. The liquid nitrogen precooling unit 12 uses a nitrogen refrigeration cycle system to reprecool the precooled hydrogen. The hydrogen cryogenic liquefaction device 13 is used to liquefy the reprecooled hydrogen. The hydrogen recirculation compressor 14 is used to pressurize the cryogenic hydrogen circulating from the cryogenic hydrogen liquefaction unit 13 and transfer it to the high-pressure hydrogen compression unit 10. The liquid hydrogen from the cryogenic hydrogen liquefaction unit 13 enters the liquid hydrogen storage and transportation system. That is, the raw material hydrogen is pre-cooled by the raw material hydrogen cooling pretreatment unit 7 and pressurized and cooled by the raw material hydrogen low-pressure compression unit 8. Then it enters the raw material hydrogen purification unit 9 to remove impurities. The purified hydrogen is pressurized and cooled again by the high-pressure hydrogen compression unit 10 and then enters the LNG pre-cooling unit 11 and the liquid nitrogen pre-cooling unit 12 for pre-cooling. Then it enters the cryogenic hydrogen liquefaction unit 13 for liquefaction. The liquid hydrogen obtained by liquefaction enters the liquid hydrogen storage and transportation system for storage and transportation. The cryogenic hydrogen circulating from the cryogenic hydrogen liquefaction unit 13 enters the LNG pre-cooling unit 11 of the hydrogen liquefaction treatment system for heat exchange. The hydrogen after heat exchange is pressurized by the hydrogen recirculation compressor 14 and then incorporated into the hydrogen at the inlet of the high-pressure hydrogen compression unit. The liquefied natural gas (LNG) at the second pressure exchanges heat with repressurized and cooled hydrogen in the LNG pre-cooling unit 11, then enters the high-pressure hydrogen compression unit 10 to exchange heat with purified hydrogen. Next, it enters the low-pressure feedstock hydrogen compression unit 8 to exchange heat with pre-cooled feedstock hydrogen, and then enters the feedstock hydrogen cooling pretreatment unit 7 to exchange heat with feedstock hydrogen. Finally, it enters the LNG receiving terminal, where it merges with the natural gas obtained from LNG vaporization in the LNG vaporization unit 5, and enters the NG metering and export unit 6. The LNG vaporization cooling energy can be used to reduce the intake temperature before each compression stage of the hydrogen compressor, improving the compression efficiency of the hydrogen compressor.

[0041] The hydrogen liquefaction process of the cryogenic hydrogen liquefaction unit 13 includes, but is not limited to, any one of the following: a pre-cooled Linde-Hampson hydrogen liquefaction process, a pre-cooled Claude cycle hydrogen liquefaction process, a pre-cooled helium expansion hydrogen liquefaction process, or an improved version of the three basic hydrogen liquefaction processes.

[0042] The high-pressure hydrogen compression unit 10 includes a high-pressure hydrogen compression unit compressor 10-1 and a high-pressure hydrogen compression unit heat exchanger 10-2 arranged sequentially. The liquefied natural gas entering the high-pressure hydrogen compression unit 10 exchanges heat with the hydrogen compressed by the high-pressure hydrogen compression unit compressor 10-1 at the high-pressure hydrogen compression unit heat exchanger 10-2. The low-pressure feedstock hydrogen compression unit 8 includes a low-pressure feedstock hydrogen compression unit compressor 8-1 and a low-pressure feedstock hydrogen compression unit heat exchanger 8-2. The liquefied natural gas entering the low-pressure feedstock hydrogen compression unit 8 exchanges heat with the hydrogen compressed by the low-pressure feedstock hydrogen compression unit compressor 8-1 at the low-pressure feedstock hydrogen 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 throttle valve 20, and a liquid nitrogen separator 21 arranged sequentially. The nitrogen compressor 18 pressurizes the nitrogen. The nitrogen heat exchanger 19 cools the pressurized nitrogen using liquefied natural gas at a second pressure. The nitrogen expander or throttle valve 20 cools the cooled nitrogen. The liquid nitrogen separator 21 separates liquid nitrogen from unliquefied nitrogen; the separated liquid nitrogen enters the liquid nitrogen pre-cooling unit 12, and the unliquefied nitrogen enters the nitrogen compressor 18. The liquefied natural gas at the second pressure exchanges heat with the pressurized nitrogen at the nitrogen heat exchanger 19, and then merges with the liquefied natural gas that has exchanged heat with pressurized and cooled hydrogen at the LNG pre-cooling unit 11, entering the hydrogen high-pressure compression unit 10. In other words, the nitrogen gas pressurized by the nitrogen compressor 18 enters the nitrogen heat exchanger 19, and then is cooled by the nitrogen expander or throttle valve 20. Liquid nitrogen is separated by the liquid nitrogen separator 21, and the unliquefied nitrogen gas is returned to the inlet of the nitrogen compressor 18. The liquid nitrogen enters the liquid nitrogen pre-cooling unit 12 of the hydrogen liquefaction treatment system to pre-cool the hydrogen. The LNG pressurized by the external booster pump 4 of the LNG tank enters the nitrogen heat exchanger 19 to exchange heat with the nitrogen gas. The LNG after exchanging heat with the nitrogen gas and the LNG after exchanging heat with the hydrogen gas merge 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 cryogenic hydrogen gas through heat exchange with ambient air via the self-pressurizing vaporizer 16. This pressurizes the liquid hydrogen in the storage tank 15, forcing it to the inlet of the liquid hydrogen pump 17. After further pressurization by the pump 17, the hydrogen is loaded onto vehicles for external transport. The cryogenic hydrogen gas volatilized from the liquid hydrogen storage tank 15 is condensed into LNG vapor and then returned to the hydrogen liquefaction system for liquefaction.

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

[0046] Low-temperature hydrogen LNG vapor gas with a temperature of approximately -250℃ to -200℃ and a pressure of approximately 50kPag to 200kPag is drawn from liquid hydrogen storage tank 15 and transported to the top of LNG storage tank 1. It then enters BOG condensation unit 3, where the cold energy of the low-temperature hydrogen gas is used to exchange heat with the BOG, causing the BOG to condense into LNG at approximately -160℃. The BOG then flows back to LNG storage tank 1 by gravity.

[0047] LNG at approximately -162°C in LNG storage tank 1 is pressurized to 0.7MPag~1.2MPag by the low-pressure pump 2 inside the tank. Part of this pressurized LNG goes to the LNG loading and cold storage circulation system, while the remainder enters the external pressurization pump 4, where it is pressurized to the pressure required for NG (LNG to gas) export, typically 6.0MPag~10.5MPag. Because it is not affected by BOG recondensation, the outlet temperature of the external pressurization pump 4 is relatively stable, typically -160°C~-158°C. A portion of this LNG is then vaporized to above 0°C by the vaporizer in the LNG vaporization unit 5, while another portion goes to the hydrogen liquefaction system and nitrogen refrigeration circulation system for LNG vaporization cold energy utilization. The NG vaporized in the LNG vaporization unit 5 and the NG after LNG vaporization cold energy utilization are combined and then exported via the metering and export unit 6.

[0048] A portion of the LNG used for LNG vaporization and cold energy utilization goes to the LNG precooling unit of the hydrogen liquefaction system, where the hydrogen is precooled to -159℃ to -157℃. After heat exchange, the LNG enters the high-pressure hydrogen compression unit 10 to exchange heat with the compressed hydrogen, and then enters the low-pressure feedstock hydrogen compression unit 8 to exchange heat with the compressed hydrogen. Finally, it enters the feedstock hydrogen cooling pretreatment unit 7 to be reheated to above 0℃, and then returns to the NG metering and export unit 6. A portion of the LNG used for LNG vaporization and cold energy utilization goes to the nitrogen heat exchanger 19 of the nitrogen refrigeration cycle system, where the N2 pressurized by the nitrogen compressor 18 is cooled to -159℃ to -157℃. Then, it passes through a nitrogen expander or throttle valve 20 to cool down to about -192℃ to -195℃. After passing through the liquid nitrogen separator 21, LN2 is separated out. The unliquefied N2 gas is returned to the inlet of the nitrogen compressor 18. The liquefied LN2 enters the liquid nitrogen precooling unit 12 of the hydrogen liquefaction treatment system, where the hydrogen is precooled to about 77K to 80K. The N2 after heat exchange and vaporization is circulated back to the inlet of the nitrogen compressor 18 of the nitrogen refrigeration cycle.

[0049] Qualified raw hydrogen passes through the raw hydrogen cooling pretreatment unit 7, where it is vaporized and pre-cooled by NG. After being pressurized and cooled by the raw hydrogen low-pressure compression unit 8, it enters the raw hydrogen purification unit 9 to remove impurities. The purified hydrogen is then pressurized and cooled by the hydrogen high-pressure compression unit 10. The pressurized hydrogen is further pre-cooled to approximately 77K–80K by the LNG pre-cooling unit 11 and the liquid nitrogen pre-cooling unit. The hydrogen flow channels of the heat exchangers in the LNG and liquid nitrogen pre-cooling units are filled with a nephrohydrogen conversion catalyst to achieve continuous catalytic conversion of nephrohydrogen at the pre-cooling temperature. Hydrogen after nephrohydrogen conversion equilibrium enters the hydrogen cryogenic liquefaction unit for liquefaction. 20K LH2 from the hydrogen cryogenic liquefaction unit is stored in the liquid hydrogen storage tank 15. Low-temperature hydrogen (if any) circulating from the hydrogen cryogenic liquefaction unit 13 enters the LNG pre-cooling unit 11 of the hydrogen liquefaction system for heat exchange. The heat-exchanged hydrogen is pressurized by the hydrogen circulating gas compressor 14 and then incorporated into the hydrogen at the inlet of the hydrogen high-pressure compression unit 10.

[0050] LH2 stored in the liquid hydrogen storage tank is converted into cryogenic hydrogen after heat exchange with ambient air via the self-pressurizing vaporizer 16. This cryogenic hydrogen then pressurizes the liquid hydrogen storage tank 15, pushing the LH2 in the tank to the inlet of the LH2 pump 17. After being pressurized by the LH2 pump 17, the hydrogen is loaded onto vehicles for external transport. The cryogenic hydrogen evaporating from the liquid hydrogen storage tank 15 goes to the BOG condensation unit 3 on the top of the LNG storage tank 1, where it exchanges heat with the BOG. ​​The hydrogen after heat exchange returns to the inlet of the hydrogen recirculation compressor 14 of the hydrogen liquefaction treatment system.

[0051] According to a second aspect of the present invention, an integrated design method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization is provided. The method includes: in the hydrogen liquefaction process, pre-cooling hydrogen using the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal and a nitrogen refrigeration cycle; in the nitrogen refrigeration cycle system, cooling compressed nitrogen using the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal; and in the LNG receiving terminal, condensing LNG vaporized gas generated in the LNG storage tank into liquefied natural gas using cryogenic hydrogen generated in the liquid hydrogen storage and transportation system. It should be understood that, without conflict, all embodiments, features, and advantages described above for the integrated design system for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization according to the first aspect of the present invention are equally applicable to the integrated design method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization according to the second aspect of the present invention. That is, all embodiments and variations thereof described above can be directly transferred and applied herein. For the sake of brevity, they will not be repeated here.

[0052] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within 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 describe the various possible combinations separately.

[0054] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An integrated design system for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminal based on cold energy utilization, characterized in that, This includes an LNG receiving terminal, a hydrogen liquefaction and processing system, and a liquid hydrogen storage and transportation system, among which: The LNG receiving terminal includes an LNG storage tank and a BOG condensation unit. The BOG condensation unit uses the low-temperature hydrogen emitted from the liquid hydrogen storage tank of the liquid hydrogen storage and transportation system to condense the LNG vapor generated in the LNG storage tank into liquefied natural gas. The LNG receiving terminal does not need to be equipped with a BOG compressor and a re-condenser. After condensing the LNG vapor, the low-temperature hydrogen emitted from the liquid hydrogen storage tank is returned to the hydrogen liquefaction processing system for liquefaction. The hydrogen liquefaction system uses the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal and the nitrogen refrigeration cycle system to pre-cool the hydrogen. The nitrogen refrigeration cycle system uses the cold energy from the vaporization of liquefied natural gas in the LNG receiving terminal to cool the compressed nitrogen. 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 gas after heat exchange with the ambient air through the self-pressurizing vaporizer, which pressurizes the liquid hydrogen storage tank and pushes the liquid hydrogen in the storage tank to the inlet of the liquid hydrogen pump. After being pressurized by the liquid hydrogen pump, it is loaded onto vehicles for external transportation.

2. The system according to claim 1, characterized in that, The LNG receiving terminal also includes, in sequence, an in-tank low-pressure pump, an external LNG booster pump, an LNG vaporization unit, and an NG metering and export unit. The in-tank low-pressure pump is used to pressurize the liquefied natural gas in the LNG storage tank to a first pressure. The external LNG booster pump is used to further pressurize the liquefied natural gas at the first pressure to a second pressure. The LNG vaporization unit is used to vaporize the liquefied natural gas at the second pressure into natural gas. The NG metering and export unit is used to export natural gas.

3. The system according to claim 2, characterized in that, Part of the liquefied natural gas at the second pressure enters the hydrogen liquefaction system for pre-cooling the hydrogen, and part enters the nitrogen refrigeration cycle system for cooling the compressed nitrogen.

4. The system according to claim 3, characterized in that, The hydrogen liquefaction system includes, in sequence, a raw material hydrogen cooling and pretreatment unit, a raw material hydrogen low-pressure compression unit, a raw material hydrogen purification unit, a hydrogen high-pressure compression unit, an LNG precooling unit, a liquid nitrogen precooling unit, a hydrogen cryogenic liquefaction device, and a hydrogen circulating gas compressor. The raw material hydrogen cooling and pretreatment unit precools the raw material hydrogen; the raw material hydrogen low-pressure compression unit pressurizes and cools the precooled raw material hydrogen; the raw material hydrogen purification unit removes impurities from the pressurized and cooled raw material hydrogen; and the hydrogen high-pressure compression unit processes the impurities from the purified hydrogen. The hydrogen undergoes repressurization and cooling. The LNG precooling unit uses liquefied natural gas at the second pressure to precool the repressurized hydrogen. The liquid nitrogen precooling unit uses the nitrogen refrigeration cycle system to re-precool the precooled hydrogen. The cryogenic hydrogen liquefaction unit is used to liquefy the re-precooled hydrogen. The hydrogen circulation compressor is used to pressurize the low-temperature hydrogen circulating from the cryogenic hydrogen liquefaction unit and transfer it to the high-pressure hydrogen compression unit. The liquid hydrogen from the cryogenic hydrogen liquefaction unit enters the liquid hydrogen storage and transportation system.

5. The system according to claim 4, characterized in that, The liquefied natural gas at the second pressure exchanges heat with the repressurized and cooled hydrogen at the LNG precooling unit, then enters the hydrogen high-pressure compression unit to exchange heat with the purified hydrogen, then enters the feedstock hydrogen low-pressure compression unit to exchange heat with the precooled feedstock hydrogen, then enters the feedstock hydrogen cooling pretreatment unit to exchange heat with the feedstock hydrogen, and then enters the LNG receiving terminal to merge with the natural gas obtained after gasification in the LNG gasification unit, and then enters the NG metering and export unit.

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

7. The system according to claim 5, characterized in that, The nitrogen refrigeration cycle system includes a nitrogen compressor, a nitrogen heat exchanger, a nitrogen expander or throttle valve, and a liquid nitrogen separator arranged in sequence. The nitrogen compressor is used to pressurize nitrogen. The nitrogen heat exchanger uses liquefied natural gas at the second pressure to cool the pressurized nitrogen. The nitrogen expander or throttle valve is used to cool the cooled nitrogen. The liquid nitrogen separator 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 exchanging heat with pressurized and cooled hydrogen at the LNG precooling unit, and enters the hydrogen high-pressure compression unit.

8. An integrated design method for hydrogen liquefaction, liquid hydrogen storage and transportation, and LNG receiving terminals based on cold energy utilization, characterized in that, The system implementation based on any one of claims 1-7 includes: During the hydrogen liquefaction process, the hydrogen is pre-cooled using the vaporization cold energy of liquefied natural gas in the LNG receiving terminal and the nitrogen refrigeration cycle system. In the nitrogen refrigeration cycle system, the compressed nitrogen is cooled using the vaporization cold energy of liquefied natural gas in the LNG receiving terminal. In the LNG receiving terminal, the low-temperature hydrogen emitted from the liquid hydrogen storage tank of the liquid hydrogen storage and transportation system is used to condense the LNG vapor generated in the LNG storage tank into liquefied natural gas, eliminating the need for the BOG compressor and recondenser in the LNG receiving terminal. The cryogenic hydrogen emitted from the liquid hydrogen storage tank is returned to the hydrogen liquefaction system for liquefaction after being condensed into LNG vapor. The liquid hydrogen stored in the liquid hydrogen storage tank is converted into low-temperature hydrogen gas after heat exchange with the ambient air through a self-pressurizing vaporizer. This pressurizes the liquid hydrogen storage tank, pushing the liquid hydrogen from the tank to the inlet of the liquid hydrogen pump. After being pressurized by the liquid hydrogen pump, the gas is loaded onto vehicles for external transportation.

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