Hydrogen liquefier

Abstract

The application relates to the field of low-temperature refrigeration technology, in particular to a hydrogen liquefying device. The hydrogen liquefying device adopts a pre-cooling mode of two primary turbine expanders in parallel in a temperature zone below liquid nitrogen, at this time, the two primary turbine expanders are expanded from high pressure to low pressure in the system, the compression energy is fully utilized under the premise of not increasing the complexity of the system. Moreover, the first turbine expander and the second turbine expander can be independently adjusted, so that the device does not interfere with each other during operation, the debugging difficulty is reduced, and the user is more convenient to use. The secondary throttling form is adopted, that is, the eighth adjusting valve and the tenth adjusting valve are arranged, the throttling refrigeration effect of hydrogen at the high-temperature side is fully utilized, the cold quantity source of the system is increased, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of cryogenic refrigeration technology, and in particular to a hydrogen liquefaction device with high safety and low energy consumption. Background Technology

[0002] With my country's goals of peaking carbon emissions and achieving carbon neutrality, the transition to a clean, low-carbon, and efficient energy system will be further strengthened. Hydrogen energy is a recognized green and renewable energy source. Ensuring a safe and smooth transition of the energy system is a significant challenge and arduous task facing my country. Against this backdrop, the unique advantages of hydrogen energy solutions give it great potential to facilitate the transition of the energy system towards a clean and low-carbon direction, holding extremely high strategic value for improving my country's energy system security and achieving carbon neutrality. The density of liquid hydrogen is 70.85 kg / m³. 3 ) is gaseous hydrogen (0.089 kg / m³) 3 It is nearly 800 times larger than hydrogen energy, which can significantly reduce storage and transportation pressure, increase single-transport volume, and require less land, making it one of the high-density storage methods for hydrogen energy.

[0003] Meanwhile, liquid hydrogen is a crucial strategic resource for the development of aerospace and the hydrogen energy industry. With the development of my country's space program and the continuous advancement of its lunar and Mars exploration plans, the demand for heavy-lift rockets is increasing, leading to a continuous rise in the demand for liquid hydrogen, the optimal energy source for liquid hydrogen-liquid oxygen engines in heavy-lift rockets. Currently, my country still relies on imported hydrogen liquefaction equipment for its liquid hydrogen production, and foreign countries consistently impose restrictions and blockades on my country regarding key hydrogen liquefaction technologies and equipment. Summary of the Invention

[0004] Research has found that the refrigeration section of a hydrogen liquefaction system can be achieved using different working fluids. One method uses hydrogen as the precooling medium, which is currently commonly used in large-scale hydrogen liquefaction plants. Another method uses helium as the precooling medium, which is commonly found in existing small and medium-sized hydrogen liquefaction plants. The existing helium-cooled hydrogen liquefaction scheme has higher safety and technological maturity, but its energy consumption is relatively high.

[0005] Therefore, this invention proposes a novel helium-cooled hydrogen liquefaction device, which effectively improves system efficiency, reduces specific power consumption, and enables convenient and rapid control. The device employs two parallel-connected single-stage turbine expanders to directly expand to low pressure. This process fully utilizes the pressure energy of the high-pressure hydrogen in the feedstock path, reducing energy consumption, and allows for independent adjustment between the two expanders. The device also utilizes a liquid nitrogen thermosiphon heat exchanger to reduce the temperature difference between the helium and hydrogen sides, maximizing the utilization of liquid nitrogen cooling energy. Furthermore, the device employs a terminal secondary throttling method to reduce the hydrogen temperature rise caused by the throttling heat effect, further reducing energy consumption.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A hydrogen liquefaction device includes a helium system, a hydrogen system, a liquid nitrogen system, a liquid hydrogen storage system, and a cold box system, wherein the helium system, hydrogen system, liquid nitrogen system, and liquid hydrogen storage system are respectively connected to the cold box system.

[0008] The cold box system includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, a sixth heat exchanger, a seventh heat exchanger, a liquid nitrogen storage tank, a helium cryogenic adsorber, a first hydrogen adsorber, a second hydrogen adsorber, a first turbine expander, a second turbine expander, a fourth regulating valve, a fifth regulating valve, a sixth regulating valve, a seventh regulating valve, an eighth regulating valve, a ninth regulating valve, a tenth regulating valve, a first pneumatic valve, a second pneumatic valve, a third pneumatic valve, a fourth pneumatic valve, and pipelines connecting the various components.

[0009] The high-pressure outlet of the helium system is connected to the high-pressure helium channel inlet of the first heat exchanger. The high-pressure helium channel outlet of the first heat exchanger is connected to the helium channel inlet of the second heat exchanger. The helium channel outlet of the second heat exchanger is connected to the inlet of the helium cryogenic adsorber. The outlet of the helium cryogenic adsorber is connected to the high-pressure helium channel inlet of the fourth heat exchanger. The first high-pressure helium channel outlet of the fourth heat exchanger is connected to the high-pressure helium channel inlet of the sixth heat exchanger via a third pneumatic valve. The second outlet is connected to the helium channel inlet of the fifth heat exchanger via a sixth regulating valve and a first turbine expander. The first high-pressure helium channel outlet of the sixth heat exchanger is connected to the... The four pneumatic valves are connected to the helium channel inlet of the seventh heat exchanger. The outlet two is connected to the helium channel inlet of the seventh heat exchanger via the seventh regulating valve and the second turbine expander. The helium channel outlet of the seventh heat exchanger is connected to the low-pressure helium channel inlet of the sixth heat exchanger. The low-pressure helium channel outlet of the sixth heat exchanger is connected to the helium channel inlet of the fifth heat exchanger. The helium channel outlet of the fifth heat exchanger is connected to the low-pressure helium channel inlet of the fourth heat exchanger. The low-pressure helium channel outlet of the fourth heat exchanger is connected to the low-pressure helium channel inlet of the first heat exchanger. The low-pressure helium channel outlet of the first heat exchanger is connected to the low-pressure inlet of the helium system.

[0010] The outlet of the hydrogen system is connected to the hydrogen channel inlet of the first heat exchanger. The hydrogen channel outlet of the first heat exchanger is connected to the hydrogen channel inlet of the second heat exchanger. The hydrogen channel outlet of the second heat exchanger is connected to the hydrogen channel inlet of the third heat exchanger via a fourth regulating valve, a first hydrogen adsorber, and a first pneumatic valve connected in sequence, or via a fifth regulating valve, a second hydrogen adsorber, and a second pneumatic valve connected in sequence. The hydrogen channel outlet of the third heat exchanger is connected to the hydrogen channel inlet of the fourth heat exchanger. The hydrogen channel outlet of the fourth heat exchanger is connected to the hydrogen channel inlet of the fifth heat exchanger. The hydrogen channel outlet of the fifth heat exchanger is connected to the hydrogen channel inlet of the sixth heat exchanger. The hydrogen channel outlet of the sixth heat exchanger is connected to the hydrogen channel inlet of the seventh heat exchanger via an eighth regulating valve. The hydrogen channel outlet of the seventh heat exchanger is connected to the liquid hydrogen storage system via a tenth regulating valve.

[0011] The liquid nitrogen system is connected to the third inlet of the liquid nitrogen storage tank via the ninth regulating valve;

[0012] The first outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the second heat exchanger, and the liquid nitrogen channel outlet of the second heat exchanger is connected to the first inlet of the liquid nitrogen storage tank; the second outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the third heat exchanger, and the liquid nitrogen channel outlet of the third heat exchanger is connected to the second inlet of the liquid nitrogen storage tank; the third outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the first heat exchanger, and the nitrogen channel outlet of the first heat exchanger is vented.

[0013] According to an embodiment of the present invention, the liquid nitrogen system is connected to the cold box system. Preferably, the liquid nitrogen system is connected to the third inlet of the liquid nitrogen storage tank through a ninth regulating valve; it is used to provide a cold source for the cold box system.

[0014] According to an embodiment of the present invention, the helium system is connected to the cold box system. Preferably, the high-pressure outlet of the helium system is connected to the high-pressure helium channel inlet of the first heat exchanger to provide high-pressure helium to the cold box system. The high-pressure helium can be recycled as a refrigerant to cool hydrogen.

[0015] According to an embodiment of the present invention, the hydrogen system is connected to the cold box system. Preferably, the outlet of the hydrogen system is connected to the hydrogen channel inlet of the first heat exchanger to provide hydrogen to the cold box system, and liquid hydrogen is obtained after being cooled by the cold box system.

[0016] According to an embodiment of the present invention, the liquid nitrogen system includes an external liquid nitrogen pipeline network, which is connected to the third inlet of the liquid nitrogen storage tank via a ninth regulating valve. The opening degree of the ninth regulating valve and the liquid level in the liquid nitrogen storage tank can be controlled using PID control.

[0017] According to an embodiment of the present invention, the hydrogen system includes an external hydrogen pipeline network, valves, and flow meters; the external hydrogen pipeline network is connected to the cold box system via the valves and flow meters. For example, the external hydrogen pipeline network is connected to the hydrogen channel inlet of the first heat exchanger via the valves and flow meters.

[0018] According to an embodiment of the present invention, the liquid hydrogen storage system includes a liquid hydrogen storage tank connected to a cold box system. Preferably, the liquid hydrogen storage tank is connected to the hydrogen channel outlet of the seventh heat exchanger via a tenth regulating valve.

[0019] According to an embodiment of the present invention, the helium system includes a compressor unit and a helium purification unit; the compressor unit includes a compressor, an oil separator, a dust collector, a helium buffer tank, a first regulating valve, a second regulating valve, and a third regulating valve;

[0020] The compressor outlet is directly connected to or connected to the inlet of the filter dust collector via an oil separator. The dust collector outlet is connected to the inlet of the first regulating valve and the inlet of the second regulating valve. The outlet of the second regulating valve is connected to the inlet of the helium buffer tank and the inlet of the third regulating valve. The outlet of the third regulating valve and the outlet of the first regulating valve are connected to the compressor inlet.

[0021] The helium purification unit includes a cryogenic purifier and a helium purity analyzer. The inlet of the cryogenic purifier and the inlet of the helium purity analyzer are respectively connected to the outlet of the dust collector F1, and the outlet of the cryogenic purifier and the outlet of the helium purity analyzer are respectively connected to the inlet of the compressor.

[0022] According to an embodiment of the present invention, the compressor is selected from an oil-impregnated compressor or an oil-free compressor; if it is selected from an oil-impregnated compressor, the outlet of the compressor is connected to the inlet of the filter dust collector through an oil separator; if it is selected from an oil-free compressor, the outlet of the compressor is directly connected to the inlet of the filter dust collector.

[0023] According to an embodiment of the present invention, the compressor can be a single unit or multiple units connected in parallel, as needed.

[0024] According to an embodiment of the present invention, the purpose of the first regulating valve is mainly to regulate the low-pressure value of the helium system. When the low-pressure value of the helium system is too low, the opening of the first regulating valve is increased to avoid exceeding the compressor power. At the same time, if a negative pressure state occurs in the pipeline, outside air can easily enter, causing the helium to be contaminated. When the low-pressure value of the helium system is too high, the opening of the first regulating valve is decreased to prevent overpressure in the low-pressure pipeline of the helium system.

[0025] According to an embodiment of the present invention, the purpose of the second regulating valve is mainly to adjust the opening of the second regulating valve through a PID control loop when the outlet pressure of the compressor is too high, so that excess helium flows into the helium buffer tank.

[0026] According to an embodiment of the present invention, the purpose of the third regulating valve is mainly to replenish helium from the helium buffer tank when the outlet pressure of the compressor is too low. The opening of the third regulating valve is adjusted by the PID control loop to allow helium from the helium buffer tank to flow into the low-pressure side of the compressor.

[0027] According to an embodiment of the present invention, the stable input and output of high and low pressure in the helium system are achieved through the combined action of the first regulating valve, the second regulating valve and the third regulating valve.

[0028] According to an embodiment of the present invention, the helium purity analyzer is used to detect the impurity content of helium in a helium system, especially the impurity content of helium on the high-pressure side, to avoid the risk of water vapor, nitrogen, oil, etc., solidifying at low temperatures and causing blockages in heat exchangers, valves, and even pipelines, leading to equipment overpressure. When the impurity content of helium in the helium system is too high, a cryogenic purifier is activated through a PID control loop to purify the helium in the helium system.

[0029] According to an embodiment of the present invention, the high-pressure helium gas compressed by the compressor flows from the high-pressure pipeline into the cryogenic purifier and the helium purity analyzer, and the low-pressure helium gas after analysis and purification flows into the low-pressure pipeline and is compressed again by the compressor.

[0030] According to an embodiment of the present invention, the outlet of the dust collector is the high-pressure outlet of the helium system, and the inlet of the compressor is the low-pressure inlet of the helium system.

[0031] According to an embodiment of the present invention, the sixth regulating valve can regulate the flow rate of helium gas flowing through the first turbine expander to ensure stable turbine operation and prevent turbine overspeed.

[0032] According to an embodiment of the present invention, the first turboexpander converts the pressure energy of high-pressure helium gas into the kinetic energy of the impeller through impeller rotation, thereby reducing the temperature and pressure of the helium gas and providing a cold source below 77.5K. The number of first turboexpanders can be single or multiple.

[0033] According to an embodiment of the present invention, the seventh regulating valve can regulate the flow rate of helium gas flowing through the second turbine expander to ensure stable turbine operation and prevent turbine overspeed.

[0034] According to an embodiment of the present invention, the second turbine expander converts the pressure energy of high-pressure helium gas into the kinetic energy of the impeller through impeller rotation, thereby reducing the temperature and pressure of the helium gas and providing a cooling source below 30K. The number of second turbine expanders can be single or multiple.

[0035] According to an embodiment of the present invention, the first turbine expander and the second turbine expander are connected in parallel, which is more conducive to the full utilization of pressure energy and the independent adjustment of the turbine expanders. Compared with the pre-cooling cycle of two turbine expanders connected in series in the prior art, since the first-stage turbine expander expands to medium pressure, it cannot effectively utilize the pressure energy of the gas, resulting in low efficiency. Moreover, the mutual series connection of the two turbine expanders increases the impact on the performance of the hydrogen liquefaction unit in actual operation.

[0036] According to an embodiment of the present invention, the first heat exchanger is a pure gas phase heat exchanger, which can reduce the temperature of high-pressure helium and hydrogen to about 80K.

[0037] According to an embodiment of the present invention, the second heat exchanger and the third heat exchanger are thermosiphon heat exchangers. The arrangement of the second heat exchanger and the third heat exchanger can further reduce the temperature of the cooled hydrogen and helium to about 77.5K, thereby realizing the full utilization of the cold energy of liquid nitrogen.

[0038] Specifically, the second heat exchanger utilizes the liquid nitrogen level difference to drive the liquid nitrogen flow. The liquid nitrogen channel of the second heat exchanger is filled with liquid nitrogen, thus the temperatures at the helium and hydrogen outlets can reach slightly above the saturation temperature of liquid nitrogen, such as 77.5 K. This heat exchanger design allows for the full utilization of the cold energy of the liquid nitrogen. In contrast, conventional heat exchangers suffer from significant temperature differences between the helium and hydrogen outlets and the liquid nitrogen, preventing the full utilization of the liquid nitrogen's cold energy. Furthermore, compared to placing the heat exchanger inside a liquid nitrogen storage tank, the second heat exchanger of this invention is easier to maintain.

[0039] Specifically, the third heat exchanger utilizes the liquid nitrogen level difference to drive the liquid nitrogen flow. The liquid nitrogen channel of the third heat exchanger is filled with liquid nitrogen, thus the temperatures at the helium and hydrogen outlets can reach slightly higher than the saturation temperature of liquid nitrogen, such as 77.5 K. This type of heat exchanger allows for the full utilization of the cold energy of the liquid nitrogen. In contrast, conventional heat exchangers suffer from significant temperature differences between the helium and hydrogen outlets and the liquid nitrogen, preventing the full utilization of the liquid nitrogen's cold energy. Furthermore, compared to placing the heat exchanger inside a liquid nitrogen storage tank, the third heat exchanger of this invention is easier to maintain.

[0040] According to an embodiment of the present invention, the hydrogen channel of the third heat exchanger is filled with a positive-negative hydrogen catalytic converter, which is beneficial to achieving isothermal conversion within the third heat exchanger.

[0041] According to an embodiment of the present invention, the hydrogen channels of the fourth heat exchanger, the fifth heat exchanger, the sixth heat exchanger, and the seventh heat exchanger are all filled with a positive-negative hydrogen catalytic conversion agent. In the fourth, fifth, sixth, and seventh heat exchangers, the hydrogen is cooled by cold helium gas, thereby realizing continuous positive-negative hydrogen conversion.

[0042] According to an embodiment of the present invention, the eighth regulating valve can regulate the flow rate of the hydrogen pipeline to achieve the first pressure reduction of liquid hydrogen. Here, the temperature of the hydrogen is relatively high and it is in the throttling cooling effect range, generating some cooling energy on its own.

[0043] According to an embodiment of the present invention, the tenth regulating valve can achieve a second throttling and depressurization of liquid hydrogen, generating subcooled liquid hydrogen, which flows into the liquid hydrogen storage tank through the pipeline.

[0044] According to an embodiment of the present invention, the fourth regulating valve and the fifth regulating valve are used to switch pipelines so that one of the first hydrogen adsorber and the second hydrogen adsorber is in operation while the other is on standby.

[0045] The beneficial effects of this invention are:

[0046] (1) In the temperature range below liquid nitrogen, a pre-cooling method using two first-stage turbine expanders connected in parallel is adopted. At this time, both first-stage turbine expanders expand from the high pressure of the system to the low pressure, so that the compression energy can be fully utilized without increasing the complexity of the system. Moreover, the first and second turbine expanders can be adjusted independently, so that the device does not interfere with each other during operation, reducing the difficulty of debugging and making it more convenient for users to use.

[0047] (2) By adopting a secondary throttling method, namely by setting the eighth and tenth regulating valves, the throttling cooling effect of hydrogen on the high-temperature side is fully utilized, which increases the source of cooling capacity of the system and improves efficiency. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the hydrogen liquefaction device of the present invention.

[0049] Reference numerals: HEX1 is the first heat exchanger, HEX2 is the second heat exchanger, HEX3 is the third heat exchanger, HEX4 is the fourth heat exchanger, HEX5 is the fifth heat exchanger, HEX6 is the sixth heat exchanger, HEX7 is the seventh heat exchanger, TANK2 is a liquid nitrogen storage tank, A1 is a helium cryogenic adsorber, A2 is the first hydrogen adsorber, A3 is the second hydrogen adsorber, T1 is the first turbine expander, T2 is the second turbine expander, CV4 is the fourth regulating valve, CV5 is the fifth regulating valve, CV6 is the sixth regulating valve, CV7 is the seventh regulating valve. Valves: CV8 is the eighth regulating valve, CV9 is the ninth regulating valve, CV10 is the tenth regulating valve, PV1 is the first pneumatic valve, PV2 is the second pneumatic valve, PV3 is the third pneumatic valve, PV4 is the fourth pneumatic valve, liquid hydrogen storage tank TANK3, V1 is a valve, FLOW1 is a flow meter, C1 is a compressor, OIL1 is an oil separator, F1 is a dust collector, TANK1 is a helium buffer tank, CV1 is the first regulating valve, CV2 is the second regulating valve, CV3 is the third regulating valve, AN1 is a cryogenic purifier, and CA1 is a helium purity analyzer. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0051] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0052] In the description of this invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment provides a hydrogen liquefaction device, which includes a helium system, a hydrogen system, a liquid nitrogen system, a liquid hydrogen storage system, and a cold box system. The helium system, hydrogen system, liquid nitrogen system, and liquid hydrogen storage system are respectively connected to the cold box system.

[0055] The cold box system includes a first heat exchanger HEX1, a second heat exchanger HEX2, a third heat exchanger HEX3, a fourth heat exchanger HEX4, a fifth heat exchanger HEX5, a sixth heat exchanger HEX6, a seventh heat exchanger HEX7, a liquid nitrogen storage tank TANK2, a helium cryogenic adsorber A1, a first hydrogen adsorber A2, a second hydrogen adsorber A3, a first turbine expander T1, a second turbine expander T2, a fourth regulating valve CV4, a fifth regulating valve CV5, a sixth regulating valve CV6, a seventh regulating valve CV7, an eighth regulating valve CV8, a ninth regulating valve CV9, a tenth regulating valve CV10, a first pneumatic valve PV1, a second pneumatic valve PV2, a third pneumatic valve PV3, a fourth pneumatic valve PV4, and pipelines connecting the components.

[0056] The high-pressure outlet of the helium system is connected to the high-pressure helium channel inlet of the first heat exchanger HEX1. The high-pressure helium channel outlet of the first heat exchanger HEX1 is connected to the helium channel inlet of the second heat exchanger HEX2. The helium channel outlet of the second heat exchanger is connected to the inlet of the helium cryogenic adsorber A1. The outlet of the helium cryogenic adsorber A1 is connected to the high-pressure helium channel inlet of the fourth heat exchanger HEX4. The high-pressure helium channel outlet one of the fourth heat exchanger HEX4 is connected to the high-pressure helium channel inlet of the sixth heat exchanger HEX6 through the third pneumatic valve PV3. The outlet two of the high-pressure helium channel is connected to the helium channel inlet of the fifth heat exchanger HEX5 through the sixth regulating valve CV6 and the first turbine expander T1. The high-pressure helium channel outlet one of the sixth heat exchanger HEX6 is connected to the helium channel inlet of the fifth heat exchanger HEX5 through the fourth pneumatic valve PV3. PV4 is connected to the helium channel inlet of the seventh heat exchanger HEX7. Outlet 2 is connected to the helium channel inlet of the seventh heat exchanger HEX7 via the seventh regulating valve CV7 and the second turbine expander T2. The helium channel outlet of the seventh heat exchanger HEX7 is connected to the low-pressure helium channel inlet of the sixth heat exchanger HEX6. The low-pressure helium channel outlet of the sixth heat exchanger HEX6 is connected to the helium channel inlet of the fifth heat exchanger HEX5. The helium channel outlet of the fifth heat exchanger HEX5 is connected to the low-pressure helium channel inlet of the fourth heat exchanger HEX4. The low-pressure helium channel outlet of the fourth heat exchanger HEX4 is connected to the low-pressure helium channel inlet of the first heat exchanger HEX1. The low-pressure helium channel outlet of the first heat exchanger HEX1 is connected to the low-pressure inlet of the helium system.

[0057] The outlet of the hydrogen system is connected to the hydrogen channel inlet of the first heat exchanger HEX1. The hydrogen channel outlet of the first heat exchanger HEX1 is connected to the hydrogen channel inlet of the second heat exchanger HEX2. The hydrogen channel outlet of the second heat exchanger HEX2 is connected to the hydrogen channel inlet of the third heat exchanger HEX3 via a fourth regulating valve CV4, a first hydrogen adsorber A2, and a first pneumatic valve PV1 connected in sequence, or via a fifth regulating valve CV5, a second hydrogen adsorber A3, and a second pneumatic valve PV2 connected in sequence. The hydrogen channel outlet of the third heat exchanger HEX3 is connected to the hydrogen channel inlet of the fourth heat exchanger HEX4. The hydrogen channel outlet of the fourth heat exchanger HEX4 is connected to the hydrogen channel inlet of the fifth heat exchanger HEX5. The hydrogen channel outlet of the fifth heat exchanger HEX5 is connected to the hydrogen channel inlet of the sixth heat exchanger HEX6. The hydrogen channel outlet of the sixth heat exchanger HEX6 is connected to the hydrogen channel inlet of the seventh heat exchanger HEX7 through the eighth regulating valve CV8. The hydrogen channel outlet of the seventh heat exchanger HEX7 is connected to the liquid hydrogen storage system through the tenth regulating valve CV10.

[0058] The liquid nitrogen system is connected to the third inlet of the liquid nitrogen storage tank via the ninth regulating valve CV9;

[0059] The first outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the second heat exchanger HEX2, and the liquid nitrogen channel outlet of the second heat exchanger HEX2 is connected to the first inlet of the liquid nitrogen storage tank; the second outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the third heat exchanger HEX3, and the liquid nitrogen channel outlet of the third heat exchanger HEX3 is connected to the second inlet of the liquid nitrogen storage tank; the third outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the first heat exchanger HEX1, and the nitrogen channel outlet of the first heat exchanger HEX1 is vented.

[0060] The liquid nitrogen system is connected to the cold box system. Preferably, the liquid nitrogen system is connected to the third inlet of the liquid nitrogen storage tank through the ninth regulating valve CV9; it is used to provide a cold source for the cold box system.

[0061] The helium system is connected to the cold box system. Preferably, the high-pressure outlet of the helium system is connected to the high-pressure helium channel inlet of the first heat exchanger HEX1 to provide high-pressure helium to the cold box system. The high-pressure helium can be recycled as a refrigerant to cool the hydrogen.

[0062] The hydrogen system is connected to the cold box system. Preferably, the outlet of the hydrogen system is connected to the hydrogen channel inlet of the first heat exchanger HEX1 to provide hydrogen to the cold box system. After being cooled by the cold box system, liquid hydrogen is obtained.

[0063] The liquid nitrogen system includes an external liquid nitrogen pipeline network, which is connected to the third inlet of the liquid nitrogen storage tank via a ninth regulating valve CV9. The opening degree of the ninth regulating valve CV9 and the liquid level in the liquid nitrogen storage tank can be controlled using PID control.

[0064] The hydrogen system includes an external hydrogen pipeline network, valves, and flow meters; the external hydrogen pipeline network is connected to the cold box system via valves and flow meters. For example, the external hydrogen pipeline network is connected to the hydrogen channel inlet of the first heat exchanger HEX1 via valves and flow meters.

[0065] The liquid hydrogen storage system includes a liquid hydrogen storage tank TANK3, which is connected to the cold box system. Preferably, the liquid hydrogen storage tank is connected to the hydrogen channel outlet of the seventh heat exchanger HEX7 via a tenth regulating valve CV10.

[0066] The helium system includes a compressor unit and a helium purification unit; the compressor unit includes a compressor C1, an oil separator OIL1, a dust collector F1, a helium buffer tank TANK1, a first regulating valve CV1, a second regulating valve CV2, and a third regulating valve CV3;

[0067] The compressor outlet is directly connected to or connected to the inlet of the filter dust collector via an oil separator. The dust collector outlet is connected to the inlet of the first regulating valve CV1 and the inlet of the second regulating valve CV2. The outlet of the second regulating valve CV2 is connected to the inlet of the helium buffer tank and the inlet of the third regulating valve CV3. The outlet of the third regulating valve CV3 and the outlet of the first regulating valve CV1 are connected to the compressor inlet.

[0068] The helium purification unit includes a cryogenic purifier AN1 and a helium purity analyzer CA1. The inlet of the cryogenic purifier and the inlet of the helium purity analyzer are respectively connected to the outlet of the dust collector F1, and the outlet of the cryogenic purifier and the outlet of the helium purity analyzer are respectively connected to the inlet of the compressor.

[0069] The compressor is selected from either an oil-impregnated compressor or an oil-free compressor; if it is selected from an oil-impregnated compressor, the outlet of the compressor is connected to the inlet of the filter dust collector through an oil separator; if it is selected from an oil-free compressor, the outlet of the compressor is directly connected to the inlet of the filter dust collector.

[0070] The compressor can be a single unit or multiple units connected in parallel, depending on the requirements.

[0071] The primary purpose of the first regulating valve CV1 is to adjust the low-pressure value of the helium system. When the low-pressure value of the helium system is too low, the opening of the first regulating valve CV1 is increased to prevent exceeding the compressor's power. Simultaneously, if a negative pressure condition occurs in the pipeline, outside air can easily enter, leading to helium contamination. When the low-pressure value of the helium system is too high, the opening of the first regulating valve CV1 is decreased to prevent overpressure in the low-pressure pipeline of the helium system.

[0072] The purpose of the second regulating valve CV2 is mainly to adjust the opening of the second regulating valve CV2 through the PID control loop when the outlet pressure of the compressor is too high, so that the excess helium flows into the helium buffer tank.

[0073] The purpose of the third regulating valve CV3 is mainly to replenish helium from the helium buffer tank when the outlet pressure of the compressor is too low. The opening of the third regulating valve CV3 is adjusted by the PID control loop to allow helium from the helium buffer tank to flow into the low-pressure side of the compressor.

[0074] The combined action of the first regulating valve CV1, the second regulating valve CV2, and the third regulating valve CV3 achieves stable input and output of high and low pressure in the helium system.

[0075] The helium purity analyzer is used to detect the impurity content of helium in the helium system, especially the impurity content of helium on the high-pressure side, to avoid the risk of water vapor, nitrogen, oil, etc. solidifying at low temperatures and causing blockages in heat exchangers, valves, and even pipelines, leading to equipment overpressure. When the impurity content of helium in the helium system is too high, a cryogenic purifier is activated through a PID control loop to purify the helium in the system.

[0076] The high-pressure helium gas compressed by the compressor flows from the high-pressure pipeline into the cryogenic purifier and helium purity analyzer. After analysis and purification, the low-pressure helium gas flows into the low-pressure pipeline and is compressed again by the compressor.

[0077] The outlet of the dust collector is the high-pressure outlet of the helium system, and the inlet of the compressor is the low-pressure inlet of the helium system.

[0078] The sixth regulating valve CV6 can regulate the flow rate of helium gas flowing through the first turbine expander T1 to ensure stable turbine operation and prevent turbine overspeed.

[0079] The first turboexpander T1 converts the pressure energy of high-pressure helium gas into the kinetic energy of the impeller through impeller rotation, thereby reducing the temperature and pressure of the helium gas and providing a cooling source below 77.5K. The number of first turboexpanders T1 can be single or multiple.

[0080] The seventh regulating valve CV7 can regulate the flow rate of helium gas through the second turbine expander T2 to ensure stable turbine operation and prevent turbine overspeed.

[0081] The second turbine expander T2 converts the pressure energy of high-pressure helium gas into the kinetic energy of the impeller through impeller rotation, thereby reducing the temperature and pressure of the helium gas and providing a cooling source below 30K. The number of second turbine expanders can be single or multiple.

[0082] The parallel connection of the first turbine expander T1 and the second turbine expander T2 is more conducive to the full utilization of pressure energy and the independent adjustment of the turbine expanders. Compared with the pre-cooling cycle of two turbine expanders in series in the prior art, since the first-stage turbine expander expands to medium pressure, it cannot effectively utilize the pressure energy of the gas, resulting in low efficiency. Moreover, the series connection of the two turbine expanders increases the impact on the performance of the hydrogen liquefaction unit in actual operation.

[0083] The first heat exchanger HEX1 is a pure gas phase heat exchanger, which can reduce the temperature of high-pressure helium and hydrogen to about 80K.

[0084] The second heat exchanger HEX2 and the third heat exchanger HEX3 are thermosiphon heat exchangers. The arrangement of the second heat exchanger HEX2 and the third heat exchanger HEX3 can further reduce the temperature of the cooled hydrogen and helium to about 77.5K, which can make full use of the cold energy of liquid nitrogen.

[0085] Specifically, the second heat exchanger HEX2 utilizes the liquid nitrogen level difference to drive the liquid nitrogen flow. At this time, the liquid nitrogen channel of the second heat exchanger HEX2 is filled with liquid nitrogen. Therefore, the temperatures at the helium and hydrogen outlets can reach slightly higher than the saturation temperature of liquid nitrogen, such as 77.5K. This heat exchanger design allows for the full utilization of the cold energy of liquid nitrogen. In contrast, in conventional heat exchangers, due to the heat exchange temperature difference, there is a significant temperature difference between the helium and hydrogen outlets and the liquid nitrogen, preventing the full utilization of the liquid nitrogen's cold energy. Furthermore, compared to placing the heat exchanger inside a liquid nitrogen storage tank, the second heat exchanger HEX2 of this invention is more convenient for maintenance.

[0086] Specifically, the third heat exchanger HEX3 utilizes the liquid nitrogen level difference to drive the liquid nitrogen flow. At this point, the liquid nitrogen channel of the third heat exchanger HEX3 is filled with liquid nitrogen. Therefore, the temperatures at the helium and hydrogen outlets can reach slightly higher than the saturation temperature of liquid nitrogen, such as 77.5K. This heat exchanger design allows for the full utilization of the cold energy of liquid nitrogen. In contrast, in conventional heat exchangers, due to the heat exchange temperature difference, there is a significant temperature difference between the helium and hydrogen outlets and the liquid nitrogen, preventing the full utilization of the liquid nitrogen's cold energy. Furthermore, compared to placing the heat exchanger inside a liquid nitrogen storage tank, the third heat exchanger HEX3 of this invention is more convenient for maintenance.

[0087] The hydrogen passage of the third heat exchanger HEX3 is filled with a positive-negative hydrogen catalytic converter, which is beneficial for achieving isothermal conversion within the third heat exchanger HEX3.

[0088] The hydrogen channels of the fourth heat exchanger HEX4, the fifth heat exchanger HEX5, the sixth heat exchanger HEX6, and the seventh heat exchanger HEX7 are all filled with ortho-parahydrogen catalytic conversion agent. In the fourth heat exchanger HEX4, the fifth heat exchanger HEX5, the sixth heat exchanger HEX6, and the seventh heat exchanger HEX7, the hydrogen is cooled by cold helium gas, realizing continuous ortho-parahydrogen conversion.

[0089] The eighth regulating valve CV8 can regulate the flow rate of the hydrogen pipeline, achieving the first pressure reduction of liquid hydrogen. Here, the temperature of the hydrogen is relatively high, and it is in the throttling cooling effect range, generating some cooling energy on its own.

[0090] The tenth regulating valve CV10 can achieve a second throttling and depressurization of liquid hydrogen, generating subcooled liquid hydrogen, which flows into the liquid hydrogen storage tank through the pipeline.

[0091] The fourth regulating valve CV4 and the fifth regulating valve CV5 are used to switch the pipeline so that one of the first hydrogen adsorber A2 and the second hydrogen adsorber A2 is working and the other is on standby.

[0092] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A hydrogen liquefaction device, the hydrogen liquefaction device comprising a helium system, a hydrogen system, a liquid nitrogen system, a liquid hydrogen storage system, and a cold box system, wherein the helium system, the hydrogen system, the liquid nitrogen system, and the liquid hydrogen storage system are respectively connected to the cold box system; The cold box system includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, a sixth heat exchanger, a seventh heat exchanger, a liquid nitrogen storage tank, a helium cryogenic adsorber, a first hydrogen adsorber, a second hydrogen adsorber, a first turbine expander, a second turbine expander, a fourth regulating valve, a fifth regulating valve, a sixth regulating valve, a seventh regulating valve, an eighth regulating valve, a ninth regulating valve, a tenth regulating valve, a first pneumatic valve, a second pneumatic valve, a third pneumatic valve, a fourth pneumatic valve, and pipelines connecting the various components. The high-pressure outlet of the helium system is connected to the high-pressure helium channel inlet of the first heat exchanger. The high-pressure helium channel outlet of the first heat exchanger is connected to the helium channel inlet of the second heat exchanger. The helium channel outlet of the second heat exchanger is connected to the inlet of the helium cryogenic adsorber. The outlet of the helium cryogenic adsorber is connected to the high-pressure helium channel inlet of the fourth heat exchanger. The first high-pressure helium channel outlet of the fourth heat exchanger is connected to the high-pressure helium channel inlet of the sixth heat exchanger via a third pneumatic valve. The second outlet is connected to the helium channel inlet of the fifth heat exchanger via a sixth regulating valve and a first turbine expander. The first high-pressure helium channel outlet of the sixth heat exchanger is connected to the... The four pneumatic valves are connected to the helium channel inlet of the seventh heat exchanger. The outlet two is connected to the helium channel inlet of the seventh heat exchanger via the seventh regulating valve and the second turbine expander. The helium channel outlet of the seventh heat exchanger is connected to the low-pressure helium channel inlet of the sixth heat exchanger. The low-pressure helium channel outlet of the sixth heat exchanger is connected to the helium channel inlet of the fifth heat exchanger. The helium channel outlet of the fifth heat exchanger is connected to the low-pressure helium channel inlet of the fourth heat exchanger. The low-pressure helium channel outlet of the fourth heat exchanger is connected to the low-pressure helium channel inlet of the first heat exchanger. The low-pressure helium channel outlet of the first heat exchanger is connected to the low-pressure inlet of the helium system. The outlet of the hydrogen system is connected to the hydrogen channel inlet of the first heat exchanger. The hydrogen channel outlet of the first heat exchanger is connected to the hydrogen channel inlet of the second heat exchanger. The hydrogen channel outlet of the second heat exchanger is connected to the hydrogen channel inlet of the third heat exchanger via a fourth regulating valve, a first hydrogen adsorber, and a first pneumatic valve connected in sequence, or via a fifth regulating valve, a second hydrogen adsorber, and a second pneumatic valve connected in sequence. The hydrogen channel outlet of the third heat exchanger is connected to the hydrogen channel inlet of the fourth heat exchanger. The hydrogen channel outlet of the fourth heat exchanger is connected to the hydrogen channel inlet of the fifth heat exchanger. The hydrogen channel outlet of the fifth heat exchanger is connected to the hydrogen channel inlet of the sixth heat exchanger. The hydrogen channel outlet of the sixth heat exchanger is connected to the hydrogen channel inlet of the seventh heat exchanger via an eighth regulating valve. The hydrogen channel outlet of the seventh heat exchanger is connected to the liquid hydrogen storage system via a tenth regulating valve. The liquid nitrogen system is connected to the third inlet of the liquid nitrogen storage tank via the ninth regulating valve; The first outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the second heat exchanger, and the liquid nitrogen channel outlet of the second heat exchanger is connected to the first inlet of the liquid nitrogen storage tank; the second outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the third heat exchanger, and the liquid nitrogen channel outlet of the third heat exchanger is connected to the second inlet of the liquid nitrogen storage tank; the third outlet of the liquid nitrogen storage tank is connected to the liquid nitrogen channel inlet of the first heat exchanger, and the nitrogen channel outlet of the first heat exchanger is vented. The hydrogen system includes an external hydrogen pipeline network, valves, and flow meters; the external hydrogen pipeline network is connected to the cold box system via valves and flow meters; the liquid hydrogen storage system includes a liquid hydrogen storage tank, which is connected to the cold box system.

2. The apparatus according to claim 1, characterized in that, The helium system includes a compressor unit and a helium purification unit; the compressor unit includes a compressor, an oil separator, a dust collector, a helium buffer tank, a first regulating valve, a second regulating valve, and a third regulating valve; The compressor outlet is directly connected to or connected to the inlet of the filter dust collector via an oil separator. The dust collector outlet is connected to the inlet of the first regulating valve and the inlet of the second regulating valve. The outlet of the second regulating valve is connected to the inlet of the helium buffer tank and the inlet of the third regulating valve. The outlet of the third regulating valve and the outlet of the first regulating valve are connected to the compressor inlet. The helium purification unit includes a cryogenic purifier and a helium purity analyzer. The inlet of the cryogenic purifier and the inlet of the helium purity analyzer are respectively connected to the outlet of the dust collector F1, and the outlet of the cryogenic purifier and the outlet of the helium purity analyzer are respectively connected to the inlet of the compressor.

3. The apparatus according to claim 2, characterized in that, The compressor is selected from either an oil-impregnated compressor or an oil-free compressor; if it is selected from an oil-impregnated compressor, the outlet of the compressor is connected to the inlet of the filter dust collector through an oil separator; if it is selected from an oil-free compressor, the outlet of the compressor is directly connected to the inlet of the filter dust collector.

4. The apparatus according to any one of claims 1-3, characterized in that, The number of the first turbine expander is one or more, and the number of the second turbine expander is one or more.

5. The apparatus according to any one of claims 1-3, characterized in that, The first heat exchanger is a pure gas phase heat exchanger.

6. The apparatus according to any one of claims 1-3, characterized in that, The second heat exchanger and the third heat exchanger are thermosiphon heat exchangers.

7. The apparatus according to any one of claims 1-3, characterized in that, The hydrogen passages of the third, fourth, fifth, sixth, and seventh heat exchangers are all filled with ortho- and para-hydrogen catalytic converters.

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