Hydrogen liquefaction process and system incorporating solar energy utilization

Abstract

The application provides a hydrogen liquefaction process and system combined with solar energy utilization. The hydrogen liquefaction process system comprises a first mixed refrigerant pre-cooling unit, a second mixed refrigerant deep cooling unit, a hydrogen liquefaction pipeline, and a solar energy heat source provided absorption refrigeration system unit; the first mixed refrigerant pre-cooling unit and the second mixed refrigerant deep cooling unit share a part of counterflow heat exchanger and normal-para hydrogen converter; the absorption refrigeration system unit is connected with the second mixed refrigerant deep cooling unit and used for providing cold energy to the second mixed refrigerant deep cooling unit; the hydrogen liquefaction pipeline sequentially passes through the counterflow heat exchanger and the normal-para hydrogen converter of the first mixed refrigerant pre-cooling unit and the second mixed refrigerant deep cooling unit. The application also provides a hydrogen liquefaction process based on the above process system.

Description

Technical Field

[0001] This invention relates to a hydrogen liquefaction process and system for utilizing solar energy, belonging to the field of hydrogen liquefaction technology. Background Technology

[0002] In recent years, the development of green, low-carbon, clean, and efficient energy has received much attention. Hydrogen, as a clean, efficient, and renewable energy source, is one of the new energy sources with great development potential and one of the most economical and effective alternatives for humanity to break free from dependence on traditional energy sources. Hydrogen energy is gradually becoming an important energy source in the global energy transformation. Liquid hydrogen, due to its high energy density, high transportation efficiency, high economic viability in market applications, and good safety, has become an economical and efficient method for hydrogen storage, transportation, and utilization. Hydrogen liquefaction technology is the core of liquid hydrogen production; however, the current traditional hydrogen liquefaction processes are complex, energy-intensive, inefficient, and costly, hindering the large-scale promotion of the liquid hydrogen industry. There is an urgent need to research more efficient liquefaction processes to reduce costs and promote the large-scale development of the liquid hydrogen industry.

[0003] Meanwhile, the integration of hydrogen liquefaction technology with renewable energy systems has become a research hotspot in recent years. Solar energy, as a clean energy source that has also received widespread attention and utilization, possesses broad application prospects and has been extensively studied in recent years. However, whether and how to effectively combine solar energy with the hydrogen energy industry to promote the utilization of new energy sources while effectively improving system energy efficiency and reducing the energy consumption of hydrogen liquefaction processes is a crucial issue that needs to be addressed in the combined utilization of hydrogen liquefaction technology and solar energy. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a novel hydrogen liquefaction process and system that combines solar energy utilization, which has advantages such as high solar energy utilization efficiency and low hydrogen liquefaction power consumption.

[0005] To achieve the above objectives, the present invention first provides a hydrogen liquefaction process system (CMR-ARS integrated system) that combines solar energy utilization. The hydrogen liquefaction process system includes a first mixed refrigerant precooling unit, a second mixed refrigerant cryogenic unit, a hydrogen liquefaction pipeline, and an absorption refrigeration system unit that provides a solar energy heat source.

[0006] The No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit share a portion of the counter-current heat exchanger and the positive-negative hydrogen converter.

[0007] The absorption refrigeration system unit is connected to the second mixed refrigerant cryogenic unit and is used to provide cooling capacity to the second mixed refrigerant cryogenic unit;

[0008] The hydrogen liquefaction pipeline passes sequentially through the countercurrent heat exchanger and the positive-negative hydrogen converter of the No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit.

[0009] In the aforementioned hydrogen liquefaction process system, the No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit share a portion of the counter-current heat exchanger and the ortho-parahydrogen converter, and are arranged in series using two different mixed refrigerants. The shared portion of the counter-current heat exchanger means that the No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit use different flow channels of the shared counter-current heat exchanger. The precooling cycle provides cooling capacity to both the high-temperature hydrogen zone and the cryogenic refrigerant, while the cryogenic cycle mainly provides cooling capacity to the low-temperature hydrogen zone. In this way, the hydrogen in the hydrogen liquefaction pipeline can be precooled. After precooling, the hydrogen enters the counter-current heat exchanger of the No. 2 mixed refrigerant cryogenic unit through the hydrogen liquefaction pipeline to complete deep cooling.

[0010] In the aforementioned hydrogen liquefaction process system, preferably, the No. 1 mixed refrigerant precooling unit includes a first-stage countercurrent heat exchanger, a first-stage positive-negative hydrogen converter, a second-stage countercurrent heat exchanger, a second-stage positive-negative hydrogen converter, a third-stage countercurrent heat exchanger, and a third-stage positive-negative hydrogen converter connected in series; this part of the countercurrent heat exchanger and the positive-negative hydrogen converter are shared with the No. 2 mixed refrigerant cryogenic unit; wherein, the first-stage countercurrent heat exchanger has six flow channels, the second-stage countercurrent heat exchanger has six flow channels, and the third-stage countercurrent heat exchanger has five flow channels;

[0011] More preferably, the hydrogen liquefaction pipeline passes sequentially through the fourth flow channel of the first-stage countercurrent heat exchanger, the first-stage ortho-parahydrogen converter, the fourth flow channel of the second-stage countercurrent heat exchanger, the second-stage ortho-parahydrogen converter, the third flow channel of the third-stage countercurrent heat exchanger, and the third-stage ortho-parahydrogen converter, thereby enabling the pre-cooling of hydrogen and the corresponding ortho-parahydrogen conversion.

[0012] In the aforementioned hydrogen liquefaction process system, preferably, the second mixed refrigerant cryogenic unit includes a series of the following components: a first-stage countercurrent heat exchanger, a first-stage positive-negative hydrogen converter, a second-stage countercurrent heat exchanger, a third-stage countercurrent heat exchanger, a fourth-stage countercurrent heat exchanger, a fifth-stage countercurrent heat exchanger, a sixth-stage countercurrent heat exchanger, and a sixth-stage positive-negative hydrogen converter. Deep cooling of hydrogen can be achieved through the fourth-stage, fifth-stage, and sixth-stage countercurrent heat exchangers. Specifically, the fourth-stage countercurrent heat exchanger, the fifth-stage countercurrent heat exchanger, and the sixth-stage countercurrent heat exchanger each have three flow channels.

[0013] More preferably, the hydrogen liquefaction pipeline passes sequentially through the fourth flow channel of the first-stage countercurrent heat exchanger, the first-stage positive-negative hydrogen converter, the fourth flow channel of the second-stage countercurrent heat exchanger, the second-stage positive-negative hydrogen converter, the third flow channel of the third-stage countercurrent heat exchanger, the third-stage positive-negative hydrogen converter, the first flow channel of the fourth-stage countercurrent heat exchanger, the fourth-stage positive-negative hydrogen converter, the first flow channel of the fifth-stage countercurrent heat exchanger, the fifth-stage positive-negative hydrogen converter, the first flow channel of the sixth-stage countercurrent heat exchanger, and the sixth-stage positive-negative hydrogen converter.

[0014] In the above-mentioned hydrogen liquefaction process system, preferably, the hydrogen liquefaction process system further includes a seventh expander and a hydrogen storage tank; wherein, the seventh expander is used to realize the expansion and liquefaction of hydrogen, and the hydrogen storage tank is used to store the liquefied liquid hydrogen.

[0015] The hydrogen liquefaction pipeline is connected to the seventh expander and the hydrogen storage tank after passing through the sixth-stage ortho-parahydrogen converter.

[0016] In the above-mentioned hydrogen liquefaction process system, preferably, the first mixed refrigerant precooling unit further includes a first mixer, a second gas-liquid separator, a first expander, a third gas-liquid separator, a second expander, a third expander, a first mixer, a second mixer, a third mixer, a first compressor, a first aftercooler, a first gas-liquid separator, a second compressor, a first pump, and a second aftercooler.

[0017] The outlet of the first mixer is connected to the inlet of the second gas-liquid separator; the gas phase outlet of the second gas-liquid separator is connected to the inlet of the second flow channel of the first-stage countercurrent heat exchanger; the outlet of the second flow channel of the first-stage countercurrent heat exchanger is connected to the inlet of the first expander; the outlet of the first expander is connected to the inlet of the second mixer; the outlet of the second mixer is connected to the inlet of the first flow channel of the first-stage countercurrent heat exchanger; the outlet of the first flow channel of the first-stage countercurrent heat exchanger is connected to the inlet of the first compressor; the outlet of the first compressor is connected to the inlet of the first aftercooler; the outlet of the first aftercooler is connected to the inlet of the first gas-liquid separator; the gas phase outlet of the first gas-liquid separator is connected to the inlet of the second compressor; the outlet of the second compressor is connected to the inlet of the second aftercooler; the outlet of the second aftercooler is connected to the inlet of the first mixer; the liquid phase outlet of the first gas-liquid separator is connected to the inlet of the first pump; and the outlet of the first pump is connected to the inlet of the first mixer.

[0018] The liquid phase outlet of the second gas-liquid separator is connected to the inlet of the third flow channel of the first-stage countercurrent heat exchanger; the outlet of the third flow channel of the first-stage countercurrent heat exchanger is connected to the inlet of the third gas-liquid separator; the gas phase outlet of the third gas-liquid separator is connected to the inlet of the second flow channel of the second-stage countercurrent heat exchanger; the outlet of the second flow channel of the second-stage countercurrent heat exchanger is connected to the inlet of the second expander; the outlet of the second expander is connected to the inlet of the third mixer; the outlet of the third mixer is connected to the inlet of the first flow channel of the second-stage countercurrent heat exchanger; and the outlet of the first flow channel of the second-stage countercurrent heat exchanger is connected to the inlet of the second mixer.

[0019] The liquid phase outlet of the third gas-liquid separator is connected to the inlet of the third flow channel of the second-stage countercurrent heat exchanger. The outlet of the third flow channel of the second-stage countercurrent heat exchanger is connected to the inlet of the second flow channel of the third-stage countercurrent heat exchanger. The outlet of the second flow channel of the third-stage countercurrent heat exchanger is connected to the inlet of the third expander. The outlet of the third expander is connected to the inlet of the first flow channel of the third-stage countercurrent heat exchanger. The outlet of the first flow channel of the third-stage countercurrent heat exchanger is connected to the inlet of the third mixer.

[0020] More preferably, the interconnected second gas-liquid separator, the first flow channel, the second flow channel and the third flow channel of the first-stage countercurrent heat exchanger, the first expander, the third gas-liquid separator, the first flow channel, the second flow channel and the third flow channel of the second-stage countercurrent heat exchanger, the second expander, the first flow channel and the second flow channel of the third-stage countercurrent heat exchanger, the third expander, the third mixer, the second mixer, the first compressor, the first aftercooler, the first gas-liquid separator, the second compressor, the first pump, the second aftercooler and the first mixer constitute a first Brayton cycle. The first Brayton cycle is used to cool the first mixed refrigerant in the first mixed refrigerant precooling unit, so as to provide cooling capacity for the first-stage countercurrent heat exchanger, the second-stage countercurrent heat exchanger, and the third-stage countercurrent heat exchanger.

[0021] In the above-mentioned hydrogen liquefaction process system, preferably, the second mixed refrigerant cryogenic unit further includes a first distributor, a fourth expander, a fifth expander, a sixth expander, a fifth mixer, a fourth mixer, a third distributor, a third compressor, a fourth compressor, a fifth compressor, a sixth compressor, a seventh compressor, a third aftercooler, a fourth aftercooler, a fifth aftercooler, a sixth aftercooler, and a seventh aftercooler.

[0022] The outlet of the fourth mixer (used to input He, Ne, and H2, and not involved in the circulation) is connected in series with the refrigerant passages of the third compressor, the third aftercooler, the fourth compressor, the fourth aftercooler, the fifth compressor, the fifth aftercooler, the sixth compressor, the sixth aftercooler, the seventh compressor, the seventh aftercooler, and the inlet of the sixth flow channel of the first-stage counter-current heat exchanger. The outlet of the sixth flow channel of the first-stage counter-current heat exchanger is connected to the inlet of the sixth flow channel of the second-stage counter-current heat exchanger. The outlet of the sixth flow channel of the second-stage counter-current heat exchanger is connected to the inlet of the fifth flow channel of the third-stage counter-current heat exchanger. The outlet of the fifth flow channel of the third-stage counter-current heat exchanger is connected to the inlet of the first distributor. The first outlet of the first distributor is connected to the inlet of the third flow channel of the fourth-stage counter-current heat exchanger. The outlet of the third flow channel of the fourth-stage counter-current heat exchanger is connected to the inlet of the fourth expander. The outlet of the first distributor is connected to the inlet of the second flow channel of the fourth-stage countercurrent heat exchanger. The outlet of the second flow channel of the fourth-stage countercurrent heat exchanger is connected to the inlet of the fifth mixer. The outlet of the fifth mixer is connected to the inlet of the fourth flow channel of the third-stage countercurrent heat exchanger. The outlet of the fourth flow channel of the third-stage countercurrent heat exchanger is connected to the inlet of the fifth flow channel of the second-stage countercurrent heat exchanger. The outlet of the fifth flow channel of the second-stage countercurrent heat exchanger is connected to the inlet of the fifth flow channel of the first-stage countercurrent heat exchanger. The outlet of the fifth flow channel of the first-stage countercurrent heat exchanger is connected to the pipeline between the fourth mixer and the third compressor. The second outlet of the first distributor is connected to the inlet of the third flow channel of the fifth-stage countercurrent heat exchanger. The outlet of the third flow channel of the fifth-stage countercurrent heat exchanger is connected to the inlet of the fifth expander. The outlet of the fifth expander is connected to the inlet of the second flow channel of the fifth-stage countercurrent heat exchanger. The outlet of the second flow channel of the fifth-stage countercurrent heat exchanger is connected to the inlet of the fifth mixer.

[0023] The third outlet of the first distributor is connected to the inlet of the third channel of the sixth-stage countercurrent heat exchanger, the outlet of the third channel of the sixth-stage countercurrent heat exchanger is connected to the inlet of the sixth expander, the outlet of the sixth expander is connected to the inlet of the second channel of the sixth-stage countercurrent heat exchanger, and the outlet of the second channel of the sixth-stage countercurrent heat exchanger is connected to the inlet of the fifth mixer.

[0024] More preferably, the third compressor, third aftercooler, fourth compressor, fourth aftercooler, fifth compressor, fifth aftercooler, sixth compressor, sixth aftercooler, seventh compressor, seventh aftercooler, first-stage counter-current heat exchanger, second-stage counter-current heat exchanger, third-stage counter-current heat exchanger, first distributor, fourth-stage counter-current heat exchanger, fourth expander, fifth-stage counter-current heat exchanger, fifth expander, sixth-stage counter-current heat exchanger, sixth expander, and fifth mixer constitute a second Brayton cycle, and the method reciprocates accordingly to form the second Brayton cycle. The second Brayton cycle is used to cool the second mixed refrigerant in the second mixed refrigerant cryogenic unit in order to provide cooling capacity for the first-stage counter-current heat exchanger, second-stage counter-current heat exchanger, third-stage counter-current heat exchanger, fourth-stage counter-current heat exchanger, fifth-stage counter-current heat exchanger, and sixth-stage counter-current heat exchanger.

[0025] The inlet of the third distributor is connected to the outlet of the absorption refrigeration system unit. The outlet of the third distributor is connected to the cooling capacity channels of the third, fourth, fifth, sixth, and seventh aftercoolers, respectively. Furthermore, these cooling capacity channels are connected to the inlet of the absorption refrigeration system unit.

[0026] In the aforementioned hydrogen liquefaction process system, preferably, the absorption refrigeration system unit is used to cool the refrigerant after the compressor pressurizes it. The purpose is to reduce the significant temperature rise of the refrigerant caused by pressurization and prevent it from entering the next equipment at excessively high temperatures. In the cryogenic unit included in the second Brayton cycle, the second mixed refrigerant provides cooling capacity to the heat exchanger, primarily generated by its expansion process in the fourth, fifth, and sixth expanders.

[0027] This absorption refrigeration system unit is a solar absorption refrigeration unit, which uses solar energy as its energy source. The absorption refrigeration system unit includes a solar collector, an energy storage device, a second pump (solution pump), a third pump, a generator, a condenser, an absorber, a regenerative heat exchanger, a first expansion valve, a second expansion valve, a sixth mixer, a seventh mixer, a seven-stage countercurrent heat exchanger, and a second distributor;

[0028] The absorption refrigeration system unit uses ammonia-water working fluid as the refrigerant in its absorption refrigeration cycle; the solar collector, energy storage device, and generator are used to absorb solar energy and convert it into energy to supply the absorption refrigeration system unit; the condenser and absorber are equipped with water flow channels for heat exchange.

[0029] The inlet of the sixth mixer is connected to the second refrigerant mixing cryogenic unit; the outlet of the sixth mixer is connected to the inlet of the seventh mixer; the outlet of the seventh mixer is connected to the inlet of the refrigerant channel of the absorber; the outlet of the refrigerant channel of the absorber is connected to the inlet of the second pump; the outlet of the second pump is connected to the inlet of the second flow channel of the regenerator; the outlet of the second flow channel of the regenerator is connected to the bottom inlet of the generator; the middle outlet of the generator is connected to the inlet of the first flow channel of the regenerator; the outlet of the first flow channel of the regenerator is connected to the inlet of the second expansion valve; and the outlet of the second expansion valve is connected to the inlet of the seventh mixer.

[0030] The top outlet of the generator is connected to the inlet of the refrigerant channel of the condenser, the outlet of the refrigerant channel of the condenser is connected to the inlet of the first flow channel of the seven-stage countercurrent heat exchanger, the outlet of the first flow channel of the seven-stage countercurrent heat exchanger is connected to the inlet of the first expansion valve, the outlet of the first expansion valve is connected to the inlet of the second distributor, the first outlet of the second distributor is connected to the inlet of the second flow channel of the seven-stage countercurrent heat exchanger, and the outlet of the second flow channel of the seven-stage countercurrent heat exchanger is connected to the inlet of the seventh mixer.

[0031] The second outlet of the second distributor is connected to the second mixed refrigerant cryogenic unit;

[0032] The bottom outlet of the generator is connected to the inlet of the solar collector, the outlet of the solar collector is connected to the inlet of the energy storage device, the outlet of the energy storage device is connected to the inlet of the third pump, and the outlet of the third pump is connected to the top inlet of the generator.

[0033] The solar-powered absorption cooling system (ARS) unit used in this invention can utilize solar energy in the most suitable way and has high cooling efficiency. On the other hand, it has good compatibility with CMR hydrogen liquefaction process, high overall energy utilization efficiency, and the advantages of being clean and environmentally friendly.

[0034] The hydrogen liquefaction process system combined with solar energy utilization provided by this invention constructs a novel CMR hydrogen liquefaction process system consisting of two mixed refrigerants circulating in series. Its precooling cycle simultaneously provides cooling capacity for the high-temperature hydrogen zone and the cryogenic refrigerant, while the cryogenic cycle primarily provides cooling capacity for the low-temperature hydrogen zone. Based on this, an absorption refrigeration system (ARS) providing a solar energy heat source is added, realizing the integration of hydrogen liquefaction and solar energy. This promotes the utilization of new energy sources while further reducing the energy consumption of hydrogen liquefaction, thus accelerating the development of hydrogen liquefaction technology. The hydrogen liquefaction process system provided by this invention reduces the energy consumption of the precooling section to 1.094 kW / kg LH2, the energy consumption of the cryogenic section to 3.88 kW / kg LH2, and the total unit energy consumption to 5.01 kW / kg LH2, significantly lower than existing general hydrogen liquefaction devices. This not only promotes the use of solar energy but also realizes the development of hydrogen liquefaction technology and the reduction of energy consumption.

[0035] The present invention also provides a hydrogen liquefaction process that combines solar energy utilization, which is carried out using the above-mentioned hydrogen liquefaction process system that combines solar energy utilization, wherein:

[0036] Hydrogen is pre-cooled to -188°C to -192°C by the No. 1 mixed refrigerant pre-cooling unit and the No. 2 mixed refrigerant cryogenic unit, and the secondary hydrogen concentration is increased to 25%-29%. Then, it is cryogenically cooled to below -253°C by the No. 2 mixed refrigerant cryogenic unit, and the secondary hydrogen concentration is increased to above 99%. Then, the pressure is reduced to below 1.7 Bar and liquefaction is achieved at the same time.

[0037] The second mixed refrigerant in the deep cryogenic unit is supplied with cooling energy by absorbing solar energy from the absorption refrigeration system unit.

[0038] In the above-mentioned hydrogen liquefaction process, preferably, the hydrogen gas, after compression and purification, first enters a primary counter-current heat exchanger, where its temperature is pre-cooled to -42°C to -46°C. Then, it enters a primary positive-negative converter to increase the concentration of secondary hydrogen to 20%-25%. The converted and heated hydrogen gas then enters a secondary counter-current heat exchanger, where its temperature is further reduced to -101°C to -105°C. Afterward, it enters a secondary positive-negative converter to increase the concentration of secondary hydrogen to 25%-29%. The converted and heated hydrogen gas then enters a tertiary counter-current heat exchanger, where its temperature is further reduced to -188°C to -192°C, completing the pre-cooling process of the first mixed refrigerant pre-cooling unit and the pre-cooling process of the second mixed refrigerant cryogenic unit. The pre-cooled hydrogen gas then first enters a tertiary positive-negative converter to increase the concentration of secondary hydrogen to... The hydrogen gas, after being converted and heated to 52%-56%, enters the fourth-stage countercurrent heat exchanger of the second mixed refrigerant cryogenic unit to cool down to -228℃ to -232℃. It then enters the fourth-stage ortho-parahydrogen converter to increase the parahydrogen concentration to 82%-86%. The converted and heated hydrogen gas then enters the fifth-stage countercurrent heat exchanger to cool down to -235℃ to -240℃. It then enters the fifth-stage ortho-parahydrogen converter to increase the parahydrogen concentration to 91%-95%. The converted and heated hydrogen gas then enters the sixth-stage countercurrent heat exchanger for cryogenic cooling to below -253℃. It then enters the sixth-stage ortho-parahydrogen converter to increase the parahydrogen concentration to over 99%. Finally, the subcooled hydrogen gas enters the hydrogen expander, where the pressure is reduced from 21 bar to 1.7 bar and liquefaction is achieved simultaneously, yielding liquid hydrogen.

[0039] In the above-mentioned hydrogen liquefaction process, preferably, the refrigerant used in the absorption refrigeration cycle of the absorption refrigeration system unit is an ammonia-water working fluid pair, wherein the ammonia molar component is 20-30% and the water molar component is 70-80%; more preferably, the ammonia molar component is 25% and the water molar component is 75%.

[0040] In the above-mentioned hydrogen liquefaction process, preferably, the absorption refrigeration system unit is a solar absorption refrigeration unit, which includes a solar thermal collection system and an absorption refrigeration cycle. The absorption refrigeration cycle cools the ammonia water to -25°C to -35°C, and then the low-temperature ammonia water is separated into several streams, which provide cooling capacity to the compressor aftercooler of the cryogenic unit, and cool this part of the compressor outlet stream to -20°C to -30°C.

[0041] In the aforementioned hydrogen liquefaction process, the No. 1 mixed refrigerant precooling unit provides cooling capacity to the first-stage countercurrent heat exchanger, the second-stage countercurrent heat exchanger, and the third-stage countercurrent heat exchanger using the No. 1 mixed refrigerant. Preferably, the molar composition of the No. 1 mixed refrigerant in the No. 1 mixed refrigerant precooling unit, by molar percentage, includes: 15-20% CH4, 15-20% C2H4, 5-10% C2H6, 15-25% C3H8, 1-5% nC4, 10-20% nC5, 0.5-2% H2, 10-20% N2, and 5-15% R14, with the sum of the molar percentages of each component being 100%. More preferably, the molar composition of the No. 1 mixed refrigerant in the No. 1 mixed refrigerant precooling unit, by molar percentage, includes: 17% CH4, 16% C2H4, 7% C2H6, 18% C3H8, 2% nC4, 15% nC5, and 1%. H2, 16% N2 and 8% R14.

[0042] In the aforementioned hydrogen liquefaction process, the No. 2 mixed refrigerant cryogenic unit provides cooling capacity to the first-stage, second-stage, third-stage, fourth-stage, fifth-stage, and sixth-stage countercurrent heat exchangers via the No. 2 mixed refrigerant. Preferably, the molar composition of the No. 2 mixed refrigerant in the No. 2 mixed refrigerant cryogenic unit, by molar percentage, comprises: 70-80% He, 5-15% N2, and 10-20% Ne, with the sum of the molar percentages of each component being 100%. More preferably, the molar composition of the No. 2 mixed refrigerant in the No. 2 mixed refrigerant cryogenic unit, by molar percentage, comprises: 78.52% He, 8.08% N2, and 13.4% Ne.

[0043] The novel hydrogen liquefaction process system (CMR-ARS integrated system) combining solar energy utilization provided by this invention includes a first mixed refrigerant precooling unit, a second mixed refrigerant cryogenic unit, a hydrogen liquefaction pipeline, and an absorption refrigeration system unit with solar energy as the heat source. The first mixed refrigerant precooling unit and the second mixed refrigerant cryogenic unit are connected in series. For the first-stage counter-current heat exchanger, the second-stage counter-current heat exchanger, and the third-stage counter-current heat exchanger, the first mixed refrigerant precooling unit completes its precooling process simultaneously with the second mixed refrigerant cryogenic unit. The absorption refrigeration system unit uses solar collectors and heat storage devices to provide heat energy for the generator and uses an ammonia-water working fluid for refrigeration circulation to cool the compressor outlet stream. While the hydrogen is precooled, it passes through three ortho- and para-hydrogen converters. After being precooled to a certain temperature, the hydrogen enters a three-stage cryogenic cycle and three ortho- and para-hydrogen converters. After cryogenic cooling, it expands and liquefies, yielding a liquid hydrogen product with a para-hydrogen concentration of over 99%, meeting storage requirements. This invention employs a two-component mixed refrigerant cyclic series system and can be combined with solar absorption refrigeration to achieve hydrogen liquefaction, effectively reducing energy consumption and greatly improving working efficiency. The liquefaction process combined with solar energy plays a positive role in promoting the use of new energy sources, reducing carbon emissions, and improving the environment.

[0044] The technical solution of this invention proposes a novel hydrogen liquefaction process system (CMR-ARS integrated system) that combines solar energy utilization. It uses two mixed refrigerants in series. The precooling cycle simultaneously provides cooling for the high-temperature hydrogen zone and the cryogenic refrigerant, while the cryogenic cycle primarily provides cooling for the low-temperature hydrogen zone. Both the precooling and cryogenic sections are mixed refrigerant cycles, utilizing solar energy absorption refrigeration systems. By combining specific process structures, mixed refrigerant composition, and process parameter values, a highly efficient hydrogen liquefaction process technology is formed. This achieves efficient matching of cooling capacity, significantly reduces the specific energy consumption of hydrogen liquefaction while efficiently utilizing solar energy, improves the heat exchange characteristics of the liquefaction process, greatly enhances refrigeration efficiency, effectively reduces the specific power consumption of the hydrogen liquefaction process, and provides a technical path for efficient utilization of solar energy. Furthermore, it can serve as a foundational technical solution for further development and improvement of subsequent technologies.

[0045] The beneficial effects of this invention are:

[0046] (1) The energy consumption of the novel hydrogen liquefaction process system combined with solar energy utilization provided by the present invention is as low as 5.010 kWh / kg LH2, with a performance coefficient of 0.2621. Compared with the existing hydrogen liquefaction system, the energy consumption of this system is greatly reduced and its performance is excellent.

[0047] (2) In the process system provided by the present invention, the two mixed refrigerant cycles are arranged in series, which makes the distribution of the refrigerant's cooling capacity more uniform, which is conducive to improving heat exchange performance and reducing energy consumption; and the precooling process involves the first three heat exchangers, while the cryogenic process involves all six heat exchangers, including the first three heat exchangers. That is, the precooling cycle can provide the cooling capacity of the hydrogen high temperature zone and the cryogenic refrigerant at the same time, while the cryogenic cycle mainly provides the cooling capacity of the hydrogen low temperature zone.

[0048] (3) The separator in the cryogenic section of the process system provided by the present invention is set with two degrees of freedom when distributing the streams, which increases the flexibility of system operation;

[0049] (4) In the process system provided by the present invention, solar energy is introduced by solar absorption refrigeration unit, which changes the cooling method of compressor outlet logistics. A heat exchanger with low temperature ammonia flow as refrigerant is used instead of water cooler to achieve the purpose of reducing cooling temperature. Moreover, after the addition of solar absorption refrigeration unit, the heat load of each cooler in the integrated system is generally reduced.

[0050] (5) The process system provided by the present invention improves the hydrogen liquefaction performance by rationally allocating the cooling capacity and adopting multi-stage positive-negative hydrogen conversion. It can ensure that the proportion of secondary hydrogen exceeds 95% while hydrogen is liquefied, and even the final proportion of secondary hydrogen can reach 99.4% in HYSYS software simulation. It can extend the time of non-destructive storage of liquid hydrogen as much as possible and reduce liquid hydrogen evaporation.

[0051] (6) The extremely high energy utilization efficiency in this invention is achieved by combining specific refrigeration combinations, specific process structures, specific mixed refrigerant compositions, and specific process parameter values. Any one of these components alone cannot achieve good technical results. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the hydrogen liquefaction process system that combines solar energy utilization, as provided in Example 1.

[0053] Explanation of main icon numbers:

[0054] Single-stage counter-current heat exchanger ~ Seven-stage counter-current heat exchanger HX-1 ~ HX-7

[0055] Stage 1 positive-negative hydrogen converter ~ Stage 6 positive-negative hydrogen converter Con-1 ~ Con-6

[0056] Mixer 1 to Mixer 7 (Mix-1 to Mix-7)

[0057] First expander to sixth expander Exp-1 to Exp-6

[0058] First splitter ~ Third splitter TEE-1 ~ TEE-3

[0059] First compressor to seventh compressor Com-1 to Com-6

[0060] First aftercooler ~ Seventh aftercooler Cooler-1 ~ Cooler-7

[0061] First gas-liquid separator ~ Third gas-liquid separator Sep-1 ~ Sep-3

[0062] hydrogen storage tank Tank

[0063] Solar collector 1 Energy storage device 2

[0064] Pump 1 to Pump 3

[0065] Generator Gen condenser Cond

[0066] Absorber Abs Regenerative Heat Exchanger HX-A

[0067] First expansion valve Vlv1 Second expansion valve Vlv2 Detailed Implementation

[0068] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0069] Example 1

[0070] This embodiment provides a hydrogen liquefaction process system that combines solar energy utilization, the structure of which is as follows: Figure 1 As shown.

[0071] The hydrogen liquefaction process system includes a No. 1 mixed refrigerant precooling unit, a No. 2 mixed refrigerant cryogenic unit, hydrogen liquefaction pipelines, an absorption refrigeration system unit with solar energy as the heat source, a seventh expander Exp-7, and a hydrogen storage tank Tank.

[0072] The No. 1 mixed refrigerant precooling unit includes a series of interconnected components: a first-stage countercurrent heat exchanger HX-1, a first-stage positive-negative hydrogen converter Con-1, a second-stage countercurrent heat exchanger HX-2, a second-stage positive-negative hydrogen converter Con-2, a third-stage countercurrent heat exchanger HX-3, a third-stage positive-negative hydrogen converter Con-3, a first mixer Mix-1, a second gas-liquid separator Sep-2, a first expander Exp-1, a third gas-liquid separator Sep-3, a second expander Exp-2, a third expander Exp-3, a first mixer Mix-1, a second mixer Mix-2, a third mixer Mix-3, a first compressor Com-1, a first aftercooler Cooler-1, a first gas-liquid separator Sep-1, a second compressor Com-2, a first pump Pump1, and a second aftercooler Cooler-2.

[0073] The No. 2 mixed refrigerant cryogenic unit includes, in series, a first-stage counter-current heat exchanger HX-1, a first-stage positive-negative hydrogen converter Con-1, a second-stage counter-current heat exchanger HX-2, a second-stage positive-negative hydrogen converter Con-2, a third-stage counter-current heat exchanger HX-3, a third-stage positive-negative hydrogen converter Con-3, a fourth-stage counter-current heat exchanger HX-4, a fourth-stage positive-negative hydrogen converter Con-4, a fifth-stage counter-current heat exchanger HX-5, a fifth-stage positive-negative hydrogen converter Con-5, a sixth-stage counter-current heat exchanger HX-6, a sixth-stage positive-negative hydrogen converter Con-6, a first distributor Tee-1, and a fourth expander E. XP-4, Fifth Expander Exp-5, Sixth Expander Exp-6, Fifth Mixer Mix-5, Fourth Mixer Mix-4, Third Flow Divider Tee-3, Fourth Mixer Mix-4, Third Compressor Com-3, Fourth Compressor Com-4, Fifth Compressor Com-5, Sixth Compressor Com-6, Seventh Compressor Com-7, Third Aftercooler Cooler-3, Fourth Aftercooler Cooler-4, Fifth Aftercooler Cooler-5, Sixth Aftercooler Cooler-6, Seventh Aftercooler Cooler-7;

[0074] The absorption refrigeration system unit includes a solar collector 1, an energy storage device 2, a second pump Pump2, a third pump Pump3, a generator Gen, a condenser Cond, an absorber Abs, a regenerative heat exchanger HX-A, a first expansion valve Vlv1, a second expansion valve Vlv2, a sixth mixer Mix-6, a seventh mixer Mix-7, a seven-stage counter-current heat exchanger HX-7, and a second distributor Tee-2.

[0075] exist Figure 1 In the process, the flow channels of the first-stage heat exchanger HX-1 to the seventh-stage heat exchanger HX-7 are named in order from top to bottom, that is, the topmost flow channel is the first flow channel.

[0076] The inlet of the first compressor Com-1 is connected to the outlet of the first flow channel of the first-stage counter-current heat exchanger HX-1. The outlet of the first compressor Com-1 is connected to the inlet of the first aftercooler Cooler-1. The outlet of the first aftercooler Cooler-1 is connected to the inlet of the first gas-liquid separator Sep-1. The gas phase outlet of the first gas-liquid separator Sep-1 is connected to the inlet of the second compressor Com-2. The outlet of the second compressor Com-2 is connected to the inlet of the second aftercooler Cooler-2. The outlet of the second aftercooler Cooler-2 is connected to the inlet of the first mixer Mix-1. The liquid phase outlet of the first gas-liquid separator Sep-1... The outlet is connected to the inlet of the first pump Pump1, the outlet of the first pump Pump1 is connected to the inlet of the first mixer Mix-1, the outlet of the first mixer Mix-1 is connected to the inlet of the second gas-liquid separator Sep-2; the gas phase outlet of the second gas-liquid separator Sep-2 is connected to the inlet of the second flow channel of the first-stage countercurrent heat exchanger HX-1, the outlet of the second flow channel of the first-stage countercurrent heat exchanger HX-1 is connected to the inlet of the first expander Exp-1, the outlet of the first expander Exp-1 is connected to the inlet of the second mixer Mix-2, and the outlet of the second mixer Mix-2 is connected to the inlet of the first flow channel of the first-stage countercurrent heat exchanger HX-1.

[0077] The liquid phase outlet of the second gas-liquid separator Sep-2 is connected to the inlet of the third flow channel of the first-stage countercurrent heat exchanger HX-1. The outlet of the third flow channel of the first-stage countercurrent heat exchanger HX-1 is connected to the inlet of the third gas-liquid separator Sep-3. The gas phase outlet of the third gas-liquid separator Sep-3 is connected to the inlet of the second flow channel of the second-stage countercurrent heat exchanger HX-2. The outlet of the second flow channel of the second-stage countercurrent heat exchanger HX-2 is connected to the inlet of the second expander Exp-2. The outlet of the second expander Exp-2 is connected to the inlet of the third mixer Mix-3. The outlet of the third mixer Mix-3 is connected to the inlet of the first flow channel of the second-stage countercurrent heat exchanger HX-2. The outlet of the first flow channel of the second-stage countercurrent heat exchanger HX-2 is connected to the inlet of the second mixer Mix-2.

[0078] The liquid phase outlet of the third gas-liquid separator Sep-3 is connected to the inlet of the third flow channel of the second-stage countercurrent heat exchanger HX-2. The outlet of the third flow channel of the second-stage countercurrent heat exchanger HX-2 is connected to the inlet of the second flow channel of the third-stage countercurrent heat exchanger HX-3. The outlet of the second flow channel of the third-stage countercurrent heat exchanger HX-3 is connected to the inlet of the third expander Exp-3. The outlet of the third expander Exp-3 is connected to the inlet of the first flow channel of the third-stage countercurrent heat exchanger HX-3. The outlet of the first flow channel of the third-stage countercurrent heat exchanger HX-3 is connected to the inlet of the third mixer Mix-3.

[0079] The outlet of the fourth mixer Mix-4 is connected in series with the refrigerant passages of the third compressor Com-3, the third aftercooler Cooler-3, the fourth compressor Com-4, the fourth aftercooler Cooler-4, the fifth compressor Com-5, the fifth aftercooler Cooler-5, the sixth compressor Com-6, the sixth aftercooler Cooler-6, the seventh compressor Com-7, the seventh aftercooler Cooler-7, and the inlet of the sixth flow channel of the first-stage counter-current heat exchanger HX-1.

[0080] The outlet of the sixth flow channel of the first-stage counter-current heat exchanger HX-1 is connected to the inlet of the sixth flow channel of the second-stage counter-current heat exchanger HX-2. The outlet of the sixth flow channel of the second-stage counter-current heat exchanger HX-2 is connected to the inlet of the fifth flow channel of the third-stage counter-current heat exchanger HX-3. The outlet of the fifth flow channel of the third-stage counter-current heat exchanger HX-3 is connected to the inlet of the first flow divider Tee-1. The first outlet of the first flow divider Tee-1 is connected to the inlet of the third flow channel of the fourth-stage counter-current heat exchanger HX-4. The outlet of the third flow channel of the fourth-stage counter-current heat exchanger HX-4 is connected to the inlet of the fourth expander Exp-4. The outlet of the fourth expander Exp-4 is connected to the inlet of the fourth-stage counter-current heat exchanger HX-2. The inlet of the second flow channel of the -4 is connected; the outlet of the second flow channel of the fourth-stage countercurrent heat exchanger HX-4 is connected to the inlet of the fifth mixer Mix-5; the outlet of the fifth mixer Mix-5 is connected to the inlet of the fourth flow channel of the third-stage countercurrent heat exchanger HX-3; the outlet of the fourth flow channel of the third-stage countercurrent heat exchanger HX-3 is connected to the inlet of the fifth flow channel of the second-stage countercurrent heat exchanger HX-2; the outlet of the fifth flow channel of the second-stage countercurrent heat exchanger HX-2 is connected to the inlet of the fifth flow channel of the first-stage countercurrent heat exchanger HX-1; and the outlet of the fifth flow channel of the first-stage countercurrent heat exchanger HX-1 is connected to the pipeline between the fourth mixer Mix-4 and the third compressor Com-3.

[0081] The second outlet of the first distributor Tee-1 is connected to the inlet of the third flow channel of the five-stage countercurrent heat exchanger HX-5. The outlet of the third flow channel of the five-stage countercurrent heat exchanger HX-5 is connected to the inlet of the fifth expander Exp-5. The outlet of the fifth expander Exp-5 is connected to the inlet of the second flow channel of the five-stage countercurrent heat exchanger HX-5. The outlet of the second flow channel of the five-stage countercurrent heat exchanger HX-5 is connected to the inlet of the fifth mixer Mix-5.

[0082] The third outlet of the first splitter Tee-1 is connected to the inlet of the third flow channel of the sixth-stage countercurrent heat exchanger HX-6. The outlet of the third flow channel of the sixth-stage countercurrent heat exchanger HX-6 is connected to the inlet of the sixth expander Exp-6. The outlet of the sixth expander Exp-6 is connected to the inlet of the second flow channel of the sixth-stage countercurrent heat exchanger HX-6. The outlet of the second flow channel of the sixth-stage countercurrent heat exchanger HX-6 is connected to the inlet of the fifth mixer Mix-5.

[0083] The inlet of the third splitter Tee-3 is connected to the second outlet of the second splitter Tee-2 of the absorption refrigeration system unit. The outlet of the third splitter Tee-3 is connected to the cooling capacity channels of the third aftercooler-3, the fourth aftercooler-4, the fifth aftercooler-5, the sixth aftercooler-6, and the seventh aftercooler-7, respectively. Furthermore, these cooling capacity channels are connected to the inlet of the sixth mixer Mix-6 of the absorption refrigeration system unit.

[0084] The outlet of the sixth mixer Mix-6 is connected to the inlet of the seventh mixer Mix-7. The outlet of the seventh mixer Mix-7 is connected to the inlet of the refrigerant passage of the absorber Abs. The outlet of the refrigerant passage of the absorber Abs is connected to the inlet of the second pump Pump2. The outlet of the second pump Pump2 is connected to the inlet of the second flow channel of the regenerating heat exchanger HX-A. The outlet of the second flow channel of the regenerating heat exchanger HX-A is connected to the bottom inlet of the generator Gen. The middle outlet of the generator Gen is connected to the inlet of the first flow channel of the regenerating heat exchanger HX-A. The outlet of the first flow channel of the regenerating heat exchanger HX-A is connected to the inlet of the second expansion valve Vlv2. The outlet of the second expansion valve Vlv2 is connected to the inlet of the seventh mixer Mix-7.

[0085] The top outlet of generator Gen is connected to the inlet of the refrigerant passage of condenser Cond. The outlet of the refrigerant passage of condenser Cond is connected to the inlet of the first flow channel of the seven-stage countercurrent heat exchanger. The outlet of the first flow channel of the seven-stage countercurrent heat exchanger is connected to the inlet of the first expansion valve Vlv1. The outlet of the first expansion valve Vlv1 is connected to the inlet of the second distributor Tee-2. The first outlet of the second distributor Tee-2 is connected to the inlet of the second flow channel of the seven-stage countercurrent heat exchanger HX-7. The outlet of the second flow channel of the seven-stage countercurrent heat exchanger HX-7 is connected to the inlet of the seventh mixer Mix-7.

[0086] The second outlet of the second splitter Tee-2 is connected to the inlet of the third splitter Tee-3;

[0087] The bottom outlet of the generator Gen is connected to the inlet of the solar collector 1, the outlet of the solar collector 1 is connected to the inlet of the energy storage device 2, the outlet of the energy storage device 2 is connected to the inlet of the third pump Pump 3, and the outlet of the third pump Pump 3 is connected to the top inlet of the generator Gen.

[0088] The hydrogen liquefaction pipeline passes sequentially through the fourth flow channel of the first-stage countercurrent heat exchanger HX-1, the first-stage positive-negative hydrogen converter Con-1, the fourth flow channel of the second-stage countercurrent heat exchanger HX-2, the second-stage positive-negative hydrogen converter Con-2, the third flow channel of the third-stage countercurrent heat exchanger HX-3, the third-stage positive-negative hydrogen converter Con-3, the first flow channel of the fourth-stage countercurrent heat exchanger HX-4, the fourth-stage positive-negative hydrogen converter Con-4, the first flow channel of the fifth-stage countercurrent heat exchanger HX-5, the fifth-stage positive-negative hydrogen converter Con-5, the first flow channel of the sixth-stage countercurrent heat exchanger HX-6, the sixth-stage positive-negative hydrogen converter Con-6, and the seventh expander Exp-7, and connects to the hydrogen storage tank Tank.

[0089] Example 2

[0090] This embodiment provides a hydrogen liquefaction process that combines solar energy utilization, which is carried out using the hydrogen liquefaction process system that combines solar energy utilization from Embodiment 1, wherein:

[0091] In the hydrogen liquefaction pipeline: Hydrogen first enters the primary counter-current heat exchanger HX1, where its temperature is pre-cooled to -42℃ to -46℃. Then, it enters the primary positive-negative converter Con-1, where the concentration of secondary hydrogen is increased to 20%–25%. The converted and heated hydrogen then enters the secondary counter-current heat exchanger HX2, where its temperature is further reduced to -101℃ to -105℃. Afterward, it enters the secondary positive-negative converter Con-2, where the concentration of secondary hydrogen is increased to 25%–29%. The converted and heated hydrogen then enters the tertiary counter-current heat exchanger HX3, where its temperature is further reduced to -188℃ to -192℃, completing the pre-cooling process of the first mixed refrigerant pre-cooling unit and the pre-cooling process of the second mixed refrigerant cryogenic unit. The pre-cooled hydrogen then first enters the tertiary positive-negative converter Con-3, where the concentration of secondary hydrogen is increased to 52%–56%, and then... After being heated, the hydrogen enters the fourth-stage countercurrent heat exchanger HX4 of the second mixed refrigerant cryogenic unit, where it is cooled to -228°C to -232°C. It then enters the fourth-stage ortho-parahydrogen converter Con-4, where the parahydrogen concentration is increased to 82%–86%. The heated hydrogen then enters the fifth-stage countercurrent heat exchanger HX5, where it is cooled to -235°C to -240°C. It then enters the fifth-stage ortho-parahydrogen converter Con-5 again, where the parahydrogen concentration is increased to 91%–95%. The heated hydrogen then enters the sixth-stage countercurrent heat exchanger HX6 for cryogenic cooling to -253°C. It then enters the sixth-stage ortho-parahydrogen converter Con-6, where the parahydrogen concentration is increased to over 99%. Finally, the subcooled hydrogen enters the hydrogen expander Exp-7, where the pressure is reduced from 21 bar to 1.7 bar and liquefaction is achieved simultaneously, yielding liquid hydrogen.

[0092] The No. 1 mixed refrigerant precooling unit includes the following steps:

[0093] The No. 1 mixed refrigerant precooling unit consists of a Brayton cycle. In molar percentage, the No. 1 mixed refrigerant is composed of 17% CH4, 16% C2H4, 7% C2H6, 18% C3H8, 2% nC4, 15% nC5, 1% H2, 16% N2 and 8% R14. The cycle simultaneously provides cooling capacity for the high-temperature hydrogen zone and the cryogenic refrigerant.

[0094] The first mixed refrigerant (flow PR18) is compressed by the first compressor Com-1 and water-cooled by the first aftercooler Cooler-1. It is then separated into two phases by the first gas-liquid separator Sep-1. The vapor and liquid phases (flows PR21 and PR22) are pressurized by the second compressor Com-2 and the first pump Pump1, respectively, and then mixed again by the first mixer Mix-1. They undergo a second separation by the second gas-liquid separator Sep-2. The separated vapor and liquid phase flows (flows PR3 and PR2) enter the second and third channels of the first-stage counter-current heat exchanger HX-1 for cooling. At the outlet of the first-stage counter-current heat exchanger HX-1, the liquid phase flow (flow PR4) enters the first expander Exp-1, while the vapor phase flow (flow PR5) is further separated into two phases (flows PR7 and PR8) and enters the second and third channels of the second-stage counter-current heat exchanger HX-2 for cooling. Similarly, the liquid phase (flow PR9) enters the second expander Exp-2, while the vapor phase (flow PR10) enters the second channel of the tertiary countercurrent heat exchanger HX-3 for further cooling. It then enters the third expander Exp-3 for expansion and cooling before returning to the first channel of the tertiary countercurrent heat exchanger HX-3 to provide cooling for itself, the cryogenic refrigerant, and the feedstock hydrogen. The low-temperature, low-pressure refrigerant flowing out of the first channel of the tertiary countercurrent heat exchanger HX-3 mixes with the low-temperature liquid refrigerant (flow PR11) at the outlet of the second expander Exp-2, and then returns to the first channel of the second countercurrent heat exchanger HX-2 to provide cooling. The low-pressure refrigerant (flow PR16) flowing out of the first channel of the second countercurrent heat exchanger HX-2 mixes with the low-temperature liquid refrigerant (flow PR6) at the outlet of the first expander Exp-1, and then returns to the first channel of the first countercurrent heat exchanger HX-1 to provide cooling. After continuous rewarming in the heat exchangers, the refrigerant returns to the inlet of the first-stage compressor Com-1 to complete the pre-cooling process.

[0095] The No. 2 mixed refrigerant cryogenic unit includes the following steps:

[0096] The No. 2 mixed refrigerant cryogenic unit consists of a Brayton cycle. In molar percentage, the No. 2 mixed refrigerant is composed of 78.52% He, 8.08% N2, and 13.4% Ne. The cycle mainly provides cooling for liquefied and subcooled hydrogen.

[0097] After undergoing five stages of compression and water cooling—compressor Com-3, aftercooler-3, compressor Com-4, aftercooler-4, compressor Com-5, aftercooler-5, compressor Com-6, aftercooler-6, compressor Com-7, and aftercooler-7—the refrigerant reaches a pressure of approximately 1000 kPa. Subsequently, it enters the sixth flow channel of the first to third stage counter-current heat exchangers HX-1 to HX-3 for pre-cooling, with the cooling temperature remaining consistent with that of the pre-coolant. At the outlet of the sixth channel of the secondary countercurrent heat exchanger HX-2, the cryogenic refrigerant is divided into streams by the first splitter Tee-1. SR15 enters the fourth-stage countercurrent heat exchanger HX-4 (also known as the first-stage cryogenic heat exchanger) in the cryogenic section for further cooling, and then enters the fourth expander Exp-4 for isentropic expansion. The low-temperature, low-pressure cryogenic refrigerant (stream SR15.b) at the expander outlet returns to the second channel of the fourth-stage countercurrent heat exchanger HX-4 to provide cooling for the feedstock hydrogen and itself in the corresponding temperature range. Streams SR16 and SR17 enter the fifth-stage countercurrent heat exchanger HX-5 (also known as the second-stage cryogenic heat exchanger) and the sixth-stage countercurrent heat exchanger HX-6 (also known as the third-stage cryogenic heat exchanger), respectively, to perform similar operations to SR15. Finally, the cryogenic refrigerant stream at the outlet of the third-stage heat exchanger is mixed in the fifth mixer, Tee-5, and then sequentially returned to the third-stage countercurrent heat exchanger HX-3, the second-stage countercurrent heat exchanger HX-2, and the first-stage countercurrent heat exchanger HX-1 to provide cooling for the feedstock hydrogen and gradually reheat. After reheating, the cryogenic refrigerant re-enters the third-stage compressor Com-3 for the next cycle.

[0098] The solar absorption cooling unit includes the following process steps:

[0099] A solar absorption refrigeration unit includes a solar thermal collection system and an absorption refrigeration cycle;

[0100] The solar thermal system includes a solar collector 1 and an energy storage device 2. The solar collector 1 absorbs solar energy and converts it into heat energy, which is then stored in the energy storage device 2. The heat energy heats the water, raising its temperature. The heated water then enters the generator Gen via a third pump 3, which heats the ammonia-water working fluid solution in the generator Gen. The ammonia-water working fluid solution contains 25% ammonia and 75% water.

[0101] The absorption refrigeration cycle includes a refrigerant forward cycle and an absorbent reverse cycle. In the forward cycle, the working fluid, ammonia refrigerant, is heated and, upon reaching its saturation point, evaporates into gaseous refrigerant R1. This gaseous refrigerant then enters the condenser (Cond) to cool and obtain room-temperature liquid refrigerant R2. R2 is then cooled by the seven-stage counter-current heat exchanger (HX-7) and passes through the first expansion valve (Vlv-1) for throttling and expansion, resulting in low-temperature liquid refrigerant R4. This R4 is then divided into two streams, R5 and R6, by the second distributor (TEE-2). Stream R5 returns to the seven-stage counter-current heat exchanger (HX-7) to provide its own cooling capacity, while stream R6 is divided into five cold streams by the third distributor (TEE-3). These streams enter the cryogenic compressor outlet cooler for heat exchange and then pass through the sixth mixer (Mix-). 6. The mixture is R13; after heat exchange and heating, the R7 and R13, along with the high-concentration absorbent after throttling and cooling, are dissolved in the absorber Abs and then transported back to the generator Gen by the second pump Pump2 to complete the refrigeration cycle; in the reverse cycle, the absorbent solution A1 first enters the regenerative heat exchanger HX-A for cooling, and then, after being throttled and depressurized by the second expansion valve Vlv2, it enters the seventh mixer Mix-7 as stream A3. After mixing with the refrigerant R7 after it provides cooling capacity, it enters the absorber Abs. After being heated in the absorber Abs, it is then transported to the generator Gen by the second pump Pump2 to start the next refrigeration cycle.

[0102] The Aspen HYSYS (V10) software was used to simulate this embodiment. The corresponding parameters of various logistics nodes in this embodiment are shown in Table 1, and the system performance that this embodiment can achieve is shown in Table 2.

[0103] Table 1

[0104]

[0105]

[0106]

[0107] Table 2

[0108]

[0109]

[0110] As can be seen from the table above, the technical solution of the present invention can effectively combine hydrogen liquefaction with solar energy utilization, thereby promoting solar energy utilization while reducing the energy consumption of the hydrogen liquefaction system and saving energy.

[0111] The above embodiments are specific implementations of the present invention and are not intended to limit the present invention in any other way. Any modifications or similar changes made based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hydrogen liquefaction process system that combines solar energy utilization, wherein, The hydrogen liquefaction process system includes a No. 1 mixed refrigerant precooling unit, a No. 2 mixed refrigerant cryogenic unit, a hydrogen liquefaction pipeline, and an absorption refrigeration system unit with solar energy as the heat source. The No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit share a portion of the counter-current heat exchanger and the positive-negative hydrogen converter. The absorption refrigeration system unit is connected to the second mixed refrigerant cryogenic unit and is used to provide cooling capacity to the second mixed refrigerant cryogenic unit; The hydrogen liquefaction pipeline passes sequentially through the counter-current heat exchanger and the positive-negative hydrogen converter of the No. 1 mixed refrigerant precooling unit and the No. 2 mixed refrigerant cryogenic unit. in: The No. 1 mixed refrigerant precooling unit includes a series of interconnected components: a first-stage countercurrent heat exchanger (HX-1), a first-stage positive-negative hydrogen converter (Con-1), a second-stage countercurrent heat exchanger (HX-2), a second-stage positive-negative hydrogen converter (Con-2), a third-stage countercurrent heat exchanger (HX-3), a third-stage positive-negative hydrogen converter (Con-3), a second gas-liquid separator (Sep-2), a first expander (Exp-1), a third gas-liquid separator (Sep-3), a second expander (Exp-2), a third expander (Exp-3), a first mixer (Mix-1), a second mixer (Mix-2), a third mixer (Mix-3), a first compressor (Com-1), a first aftercooler (Cooler-1), a first gas-liquid separator (Sep-1), a second compressor (Com-2), a first pump (Pump1), and a second aftercooler (Cooler-2). The second mixed refrigerant cryogenic unit includes, in series, a first-stage counter-current heat exchanger (HX-1), a first-stage positive-negative hydrogen converter (Con-1), a second-stage counter-current heat exchanger (HX-2), a second-stage positive-negative hydrogen converter (Con-2), a third-stage counter-current heat exchanger (HX-3), a third-stage positive-negative hydrogen converter (Con-3), a fourth-stage counter-current heat exchanger (HX-4), a fourth-stage positive-negative hydrogen converter (Con-4), a fifth-stage counter-current heat exchanger (HX-5), a fifth-stage positive-negative hydrogen converter (Con-5), a sixth-stage counter-current heat exchanger (HX-6), a sixth-stage positive-negative hydrogen converter (Con-6), a first splitter (Tee-1), and a fourth expansion... Expander (Exp-4), fifth expander (Exp-5), sixth expander (Exp-6), fifth mixer (Mix-5), fourth mixer (Mix-4), third distributor (Tee-3), third compressor (Com-3), fourth compressor (Com-4), fifth compressor (Com-5), sixth compressor (Com-6), seventh compressor (Com-7), third aftercooler (Cooler-3), fourth aftercooler (Cooler-4), fifth aftercooler (Cooler-5), sixth aftercooler (Cooler-6), seventh aftercooler (Cooler-7); The outlet of the first mixer (Mix-1) is connected to the inlet of the second gas-liquid separator (Sep-2); the gas phase outlet of the second gas-liquid separator (Sep-2) is connected to the inlet of the second flow channel of the first-stage counter-current heat exchanger (HX-1); the outlet of the second flow channel of the first-stage counter-current heat exchanger (HX-1) is connected to the inlet of the first expander (Exp-1); the outlet of the first expander (Exp-1) is connected to the inlet of the second mixer (Mix-2); the outlet of the second mixer (Mix-2) is connected to the inlet of the first flow channel of the first-stage counter-current heat exchanger (HX-1); the outlet of the first flow channel of the first-stage counter-current heat exchanger (HX-1) is connected to the inlet of the first compressor (Com-1); the first compressor (Com-1)... The outlet of the first aftercooler (Cooler-1) is connected to the inlet of the first gas-liquid separator (Sep-1), the gas phase outlet of the first gas-liquid separator (Sep-1) is connected to the inlet of the second compressor (Com-2), the outlet of the second compressor (Com-2) is connected to the inlet of the second aftercooler (Cooler-2), the outlet of the second aftercooler (Cooler-2) is connected to the inlet of the first mixer (Mix-1), the liquid phase outlet of the first gas-liquid separator (Sep-1) is connected to the inlet of the first pump (Pump1), and the outlet of the first pump (Pump1) is connected to the inlet of the first mixer (Mix-1). The liquid phase outlet of the second gas-liquid separator (Sep-2) is connected to the inlet of the third flow channel of the first-stage countercurrent heat exchanger (HX-1). The outlet of the third flow channel of the first-stage countercurrent heat exchanger (HX-1) is connected to the inlet of the third gas-liquid separator (Sep-3). The gas phase outlet of the third gas-liquid separator (Sep-3) is connected to the inlet of the second flow channel of the second-stage countercurrent heat exchanger (HX-2). The outlet of the second flow channel of the second-stage countercurrent heat exchanger (HX-2) is connected to the inlet of the second expander (Exp-2). The outlet of the second expander (Exp-2) is connected to the inlet of the third mixer (Mix-3). The outlet of the third mixer (Mix-3) is connected to the inlet of the first flow channel of the second-stage countercurrent heat exchanger (HX-2). The outlet of the first flow channel of the second-stage countercurrent heat exchanger (HX-2) is connected to the inlet of the second mixer (Mix-2). The liquid phase outlet of the third gas-liquid separator (Sep-3) is connected to the inlet of the third flow channel of the second-stage countercurrent heat exchanger (HX-2). The outlet of the third flow channel of the second-stage countercurrent heat exchanger (HX-2) is connected to the inlet of the second flow channel of the third-stage countercurrent heat exchanger (HX-3). The outlet of the second flow channel of the third-stage countercurrent heat exchanger (HX-3) is connected to the inlet of the third expander (Exp-3). The outlet of the third expander (Exp-3) is connected to the inlet of the first flow channel of the third-stage countercurrent heat exchanger (HX-3). The outlet of the first flow channel of the third-stage countercurrent heat exchanger (HX-3) is connected to the inlet of the third mixer (Mix-3). The outlet of the fourth mixer (Mix-4) is connected in series with the refrigerant passages of the third compressor (Com-3), the third aftercooler (Cooler-3), the fourth compressor (Com-4), the fourth aftercooler (Cooler-4), the fifth compressor (Com-5), the fifth aftercooler (Cooler-5), the sixth compressor (Com-6), the sixth aftercooler (Cooler-6), the seventh compressor (Com-7), the seventh aftercooler (Cooler-7), and the inlet of the sixth flow channel of the first-stage counter-current heat exchanger (HX-1). The outlet of the sixth flow channel of (HX-1) is connected to the inlet of the sixth flow channel of the second-stage counter-current heat exchanger (HX-2). The outlet of the sixth flow channel of the second-stage counter-current heat exchanger (HX-2) is connected to the inlet of the fifth flow channel of the third-stage counter-current heat exchanger (HX-3). The outlet of the fifth flow channel of the third-stage counter-current heat exchanger (HX-3) is connected to the inlet of the first flow divider (Tee-1). The first outlet of the first flow divider (Tee-1) is connected to the inlet of the third flow channel of the fourth-stage counter-current heat exchanger (HX-4). The outlet of the third flow channel of the fourth-stage counter-current heat exchanger (HX-4) is connected to the inlet of the fourth expander (Exp-4). The outlet of (Exp-4) is connected to the inlet of the second flow channel of the fourth-stage counter-current heat exchanger (HX-4). The outlet of the second flow channel of the fourth-stage counter-current heat exchanger (HX-4) is connected to the inlet of the fifth mixer (Mix-5). The outlet of the fifth mixer (Mix-5) is connected to the inlet of the fourth flow channel of the third-stage counter-current heat exchanger (HX-3). The outlet of the fourth flow channel of the third-stage counter-current heat exchanger (HX-3) is connected to the inlet of the fifth flow channel of the second-stage counter-current heat exchanger (HX-2). The outlet of the fifth flow channel of the second-stage counter-current heat exchanger (HX-2) is connected to the inlet of the fifth flow channel of the first-stage counter-current heat exchanger (HX-1). The outlet of the fifth flow channel of the heat exchanger (HX-1) is connected to the pipeline between the fourth mixer (Mix-4) and the third compressor (Com-3). The second outlet of the first distributor (Tee-1) is connected to the inlet of the third flow channel of the five-stage countercurrent heat exchanger (HX-5). The outlet of the third flow channel of the five-stage countercurrent heat exchanger (HX-5) is connected to the inlet of the fifth expander (Exp-5). The outlet of the fifth expander (Exp-5) is connected to the inlet of the second flow channel of the five-stage countercurrent heat exchanger (HX-5). The outlet of the second flow channel of the five-stage countercurrent heat exchanger (HX-5) is connected to the inlet of the fifth mixer (Mix-5). The third outlet of the first splitter (Tee-1) is connected to the inlet of the third flow channel of the six-stage countercurrent heat exchanger (HX-6), the outlet of the third flow channel of the six-stage countercurrent heat exchanger (HX-6) is connected to the inlet of the sixth expander (Exp-6), the outlet of the sixth expander (Exp-6) is connected to the inlet of the second flow channel of the six-stage countercurrent heat exchanger (HX-6), and the outlet of the second flow channel of the six-stage countercurrent heat exchanger (HX-6) is connected to the inlet of the fifth mixer (Mix-5). The inlet of the third distributor (Tee-3) is connected to the outlet of the absorption refrigeration system unit. The outlet of the third distributor (Tee-3) is connected to the cooling capacity channels of the third aftercooler (Cooler-3), the fourth aftercooler (Cooler-4), the fifth aftercooler (Cooler-5), the sixth aftercooler (Cooler-6), and the seventh aftercooler (Cooler-7), respectively. Furthermore, these cooling capacity channels are connected to the inlet of the absorption refrigeration system unit. The absorption refrigeration system unit includes a solar collector (1), an energy storage device (2), a second pump (Pump2), a third pump (Pump3), a generator (Gen), a condenser (Cond), an absorber (Abs), a regenerative heat exchanger (HX-A), a first expansion valve (Vlv1), a second expansion valve (Vlv2), a sixth mixer (Mix-6), a seventh mixer (Mix-7), a seven-stage countercurrent heat exchanger (HX-7), and a second distributor (Tee-2). The inlet of the sixth mixer (Mix-6) is connected to the second refrigerant mixing cryogenic unit; the outlet of the sixth mixer (Mix-6) is connected to the inlet of the seventh mixer (Mix-7); the outlet of the seventh mixer (Mix-7) is connected to the inlet of the refrigerant channel of the absorber (Abs); the outlet of the refrigerant channel of the absorber (Abs) is connected to the inlet of the second pump (Pump2); and the outlet of the second pump (Pump2) is connected to the heat exchanger. The inlet of the second flow channel of the heat exchanger (HX-A) is connected, the outlet of the second flow channel of the heat exchanger (HX-A) is connected to the bottom inlet of the generator (Gen), the middle outlet of the generator (Gen) is connected to the inlet of the first flow channel of the heat exchanger (HX-A), the outlet of the first flow channel of the heat exchanger (HX-A) is connected to the inlet of the second expansion valve (Vlv2), and the outlet of the second expansion valve (Vlv2) is connected to the inlet of the seventh mixer (Mix-7). The top outlet of the generator (Gen) is connected to the inlet of the refrigerant passage of the condenser (Cond), the outlet of the refrigerant passage of the condenser (Cond) is connected to the inlet of the first flow channel of the seven-stage countercurrent heat exchanger (HX-7), the outlet of the first flow channel of the seven-stage countercurrent heat exchanger (HX-7) is connected to the inlet of the first expansion valve (Vlv1), the outlet of the first expansion valve (Vlv1) is connected to the inlet of the second distributor (Tee-2), the first outlet of the second distributor (Tee-2) is connected to the inlet of the second flow channel of the seven-stage countercurrent heat exchanger (HX-7), and the outlet of the second flow channel of the seven-stage countercurrent heat exchanger (HX-7) is connected to the inlet of the seventh mixer (Mix-7). The second outlet of the second distributor (Tee-2) is connected to the second mixed refrigerant cryogenic unit; The bottom outlet of the generator (Gen) is connected to the inlet of the solar collector (1), the outlet of the solar collector (1) is connected to the inlet of the energy storage device (2), the outlet of the energy storage device (2) is connected to the inlet of the third pump (Pump3), and the outlet of the third pump (Pump3) is connected to the top inlet of the generator (Gen). The hydrogen liquefaction pipeline passes sequentially through the fourth flow channel of the first-stage countercurrent heat exchanger (HX-1), the first-stage positive-negative hydrogen converter (Con-1), the fourth flow channel of the second-stage countercurrent heat exchanger (HX-2), the second-stage positive-negative hydrogen converter (Con-2), the third flow channel of the third-stage countercurrent heat exchanger (HX-3), the third-stage positive-negative hydrogen converter (Con-3), the first flow channel of the fourth-stage countercurrent heat exchanger (HX-4), the fourth-stage positive-negative hydrogen converter (Con-4), the first flow channel of the fifth-stage countercurrent heat exchanger (HX-5), the fifth-stage positive-negative hydrogen converter (Con-5), the first flow channel of the sixth-stage countercurrent heat exchanger (HX-6), and the sixth-stage positive-negative hydrogen converter (Con-6).

2. The hydrogen liquefaction process system according to claim 1, wherein, The hydrogen liquefaction process system also includes a seventh expander (Exp-7) and a hydrogen storage tank. The hydrogen liquefaction pipeline is connected to the seventh expander (Exp-7) and the hydrogen storage tank after passing through the sixth-stage ortho-parahydrogen converter (Con-6).

3. A hydrogen liquefaction process that combines solar energy utilization, wherein the process is carried out using the hydrogen liquefaction process system that combines solar energy utilization as described in claim 1 or 2, wherein: Hydrogen is pre-cooled to -188°C to -192°C by the No. 1 mixed refrigerant pre-cooling unit and the No. 2 mixed refrigerant cryogenic unit, and the secondary hydrogen concentration is increased to 25%-29%. Then, it is cryogenically cooled to below -253°C by the No. 2 mixed refrigerant cryogenic unit, and the secondary hydrogen concentration is increased to above 99%. Then, the pressure is reduced to below 1.7 Bar and liquefaction is achieved simultaneously. The second mixed refrigerant in the deep cryogenic unit is supplied with cooling energy by absorbing solar energy from the absorption refrigeration system unit.

4. The hydrogen liquefaction process according to claim 3, wherein, The hydrogen gas first enters the primary counter-current heat exchanger (HX-1), where its temperature is pre-cooled to -42°C to -46°C. Then, it enters the primary positive-negative hydrogen converter (Con-1) to increase the secondary hydrogen concentration to 20%-25%. After conversion and heating, the hydrogen gas enters the secondary counter-current heat exchanger (HX-2), where its temperature is further reduced to -101°C to -105°C. It then enters the secondary positive-negative hydrogen converter (Con-2) again, where the secondary hydrogen concentration is increased to 25%-29%. After conversion and heating, the hydrogen gas enters the tertiary counter-current heat exchanger (HX-3), where its temperature is further reduced to -188°C to -192°C, completing the pre-cooling process of the first mixed refrigerant pre-cooling unit and the pre-cooling process of the second mixed refrigerant cryogenic unit. The pre-cooled hydrogen gas then enters the tertiary positive-negative hydrogen converter (Con-3) to increase the secondary hydrogen concentration to 52%-56%. After conversion and heating... The hydrogen gas enters the fourth-stage countercurrent heat exchanger (HX-4) of the second mixed refrigerant cryogenic unit and is cooled to -228°C to -232°C. Then it enters the fourth-stage ortho-parahydrogen converter (Con-4) to increase the parahydrogen concentration to 82%-86%. The converted and heated hydrogen gas enters the fifth-stage countercurrent heat exchanger (HX-5) and is cooled to -235°C to -240°C. Then it enters the fifth-stage ortho-parahydrogen converter (Con-5) to increase the parahydrogen concentration to 91%-95%. The converted and heated hydrogen gas enters the sixth-stage countercurrent heat exchanger (HX-6) for cryogenic cooling to below -253°C. Then it enters the sixth-stage ortho-parahydrogen converter (Con-6) to increase the parahydrogen concentration to over 99%. Finally, the subcooled hydrogen gas enters the seventh expander (Exp-7), where the pressure is reduced from 21 bar to 1.7 bar and liquefaction is achieved simultaneously, yielding liquid hydrogen product.

5. The hydrogen liquefaction process according to claim 3 or 4, wherein: In terms of molar percentage, the molar composition of the No. 1 mixed refrigerant in the No. 1 mixed refrigerant precooling unit includes: 15-20% CH4, 15-20% C2H4, 5-10% C2H6, 15-25% C3H8, 1-5% nC4, 10-20% nC5, 0.5-2% H2, 10-20% N2 and 5-15% R14, and the sum of the molar percentages of each component is 100%.

6. The hydrogen liquefaction process according to claim 5, wherein, In molar percentage, the molar composition of the No. 1 mixed refrigerant in the No. 1 mixed refrigerant precooling unit includes: 17% CH4, 16% C2H4, 7% C2H6, 18% C3H8, 2% nC4, 15% nC5, 1% H2, 16% N2 and 8% R14.

7. The hydrogen liquefaction process according to claim 5, wherein, In molar percentage, the molar composition of the No. 2 mixed refrigerant in the No. 2 mixed refrigerant cryogenic unit includes: 70-80% He, 5-15% N2, and 10-20% Ne, with the sum of the molar percentages of each component being 100%.

8. The hydrogen liquefaction process according to claim 7, wherein, In molar percentage, the molar composition of the No. 2 mixed refrigerant in the No. 2 mixed refrigerant cryogenic unit includes: 78.52% He, 8.08% N2, and 13.4% Ne.

9. The hydrogen liquefaction process according to claim 5, wherein, The absorption refrigeration system unit uses an ammonia-water working fluid pair as its refrigerant in the absorption refrigeration cycle. The ammonia molar component of the ammonia-water working fluid pair is 20-30%, and the water molar component is 70-80%.

10. The hydrogen liquefaction process according to claim 9, wherein, The ammonia molar component in the ammonia-water working medium is 25%, and the water molar component is 75%.

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