A device for hydrogen cryogenic triple-loop refrigeration

Abstract

This invention discloses a three-loop cryogenic refrigeration device for hydrogen, relating to the field of hydrogen liquefaction technology. The device includes a raw hydrogen supply system, a normal-to-parahydrogen conversion system, a three-loop hydrogen refrigeration system, a liquid hydrogen collection and subcooling system, and a gas recovery and circulation system. The raw hydrogen is sequentially cooled by a pre-cooling box and a multi-stage heat exchanger before entering the normal-to-parahydrogen converter to be converted into parahydrogen, and then separated by flash evaporation to obtain liquid hydrogen. The three-loop refrigeration system employs three methods—high-pressure hydrogen expansion, medium-pressure liquid hydrogen throttling, and low-pressure flash vapor recovery—to provide synergistic cooling, achieving precise matching of cooling capacity across different temperature zones. This invention uses hydrogen itself as the refrigerant, resulting in low refrigerant cost. The synergistic three-loop refrigeration reduces heat exchange temperature differences and flash evaporation losses. Simultaneously, expansion work recovery and full parahydrogen conversion improve system stability and liquid hydrogen quality, making it suitable for large-scale liquid hydrogen production.

Description

Technical Field

[0001] This utility model relates to the fields of cryogenic refrigeration and hydrogen liquefaction, and in particular to a device for cryogenic triple-loop refrigeration of hydrogen. Background Technology

[0002] To achieve the goals of "peak carbon emissions by 2030 and carbon neutrality by 2060," hydrogen is an important carrier for replacing traditional fossil fuels. However, the low density of hydrogen gas is not conducive to transportation. Liquid hydrogen at atmospheric pressure has a density of 70 kg / m³, which is several times that of high-pressure gaseous hydrogen, giving it a significant advantage as a carrier for transportation.

[0003] Currently, hydrogen liquefaction is achieved through a combination of pre-cooling and deep cryogenic refrigeration. Deep cryogenic refrigeration often directly employs a helium Brayton cycle or a hydrogen dual-pressure Claude refrigeration cycle. However, this method suffers from problems such as high refrigerant costs, high energy consumption, and difficulty in recovering flash vapor. For example:

[0004] Chinese patent CN110657633B discloses a hydrogen liquefaction system that uses helium Brayton cycle refrigeration and is equipped with two oil-lubricated helium screw compressors, a multi-stage oil separator, and four helium expanders in series. It has problems such as high energy consumption, high refrigerant cost, and inability to recover flash vapor. It is also prone to risks such as hydrogen freezing blockage and oil contamination. It is mainly used in small and medium-sized (≤5 tons / day) hydrogen liquefaction plants. Chinese patent CN117146526A discloses a hydrogen liquefaction device using hydrogen-helium-neon mixed gas expansion refrigeration. It includes a flash vapor compressor, two hydrogen-helium-neon mixed gas compressors, a three-stage expander, a hydrogen-helium-neon recovery tank, a helium storage tank, and a neon storage tank. The cryogenic process employs a hydrogen-helium-neon mixed gas expansion refrigeration cycle. The mixed gas composition is 2.5 mol% hydrogen, 63.3 mol% helium, and 34.2 mol% neon. This process suffers from problems such as complex refrigerant storage equipment, difficulty in refrigerant proportioning, and very high refrigerant costs. Furthermore, to prevent neon freezing in the mixed gas, the refrigeration temperature is ≥-247℃, resulting in a very large amount of hydrogen flash vapor after liquid hydrogen throttling. A separate flash vapor compressor is required, leading to high investment and operating costs. Chinese patent CN113446815B discloses a hydrogen liquefaction device and its usage method using a hybrid refrigeration system. It employs a conventional hydrogen dual-pressure Claude cryogenic refrigeration cycle, equipped with a hydrogen refrigeration cycle compressor unit and two two-stage series-connected hydrogen booster turbine expanders operating in parallel. However, this system suffers from high energy consumption and unstable flow distribution. Furthermore, flash vapor is recovered via an ejector. In engineering applications, the liquid hydrogen storage tank and the cryogenic chamber must maintain a relatively large safety distance. The long flash vapor pipeline is prone to heat leakage and temperature rise, which is highly detrimental to hydrogen liquefaction. Utility Model Content

[0005] The purpose of this invention is to provide a hydrogen cryogenic triple-loop refrigeration device to solve the problems existing in the prior art.

[0006] This utility model is achieved using the following technical solution: a hydrogen cryogenic triple-loop refrigeration device, comprising a raw material hydrogen supply system, a neutral hydrogen conversion system, a triple-loop hydrogen refrigeration system, a liquid hydrogen collection and subcooling system, and a gas recovery and circulation system; wherein:

[0007] The raw material hydrogen supply system includes a pre-cooling box, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, and a quaternary heat exchanger connected in sequence. The raw material hydrogen undergoes progressive heat exchange and cooling in multiple heat exchangers to form a low-temperature hydrogen channel. The gradient cooling of hydrogen is achieved through the multi-stage heat exchangers, which significantly improves the cooling efficiency.

[0008] The so-and-para hydrogen conversion system includes a filter and a so-and-para hydrogen converter, which are located between the outlet of the four-stage heat exchanger and the liquid hydrogen collection system. The outlet of the cryogenic hydrogen channel is connected to the inlet via the so-and-para hydrogen converter, and the outlet of the filter is connected to the inlet of the atmospheric pressure hydrogen flash tank to complete the hydrogen structure conversion and flash separation. The proportion of para hydrogen is increased through catalytic conversion, thereby enhancing the stability of liquid hydrogen.

[0009] The three-loop hydrogen refrigeration system includes:

[0010] First loop: The outlet of the high-pressure hydrogen compressor is sequentially connected to the inlet of the first-stage heat exchanger, the inlet of the first-stage expander, the second-stage heat exchanger, the second-stage expander, the third-stage heat exchanger, and the third-stage expander, forming a step-by-step adiabatic expansion path. After expansion, the hydrogen flows back to the reheat channel of each stage of heat exchanger, and then merges with the refrigerant of other loops; the deep cryogenic cooling capacity is achieved by using the expander for refrigeration.

[0011] Second loop: High-pressure liquid hydrogen enters the circulating hydrogen separator after passing through valve six. The separated liquid and gas phases pass through the intermediate cooling channels of the three-stage heat exchanger, the two-stage heat exchanger, and the first-stage heat exchanger in sequence. After completing the release of cold energy in the medium-temperature zone, they flow back to the inlet of the medium-pressure hydrogen compressor, forming a closed-loop cooling path.

[0012] The third loop: another stream of liquid hydrogen separated from the circulating hydrogen separator enters the flash tank after being throttled by valve eight, and then passes through valve nine, the liquid hydrogen storage tank, and the BOG reheater in sequence before returning to the inlet of the low-pressure hydrogen compressor, forming a gas recovery path.

[0013] The liquid hydrogen collection and subcooling system includes: an atmospheric pressure hydrogen flash tank, a liquid hydrogen subcooler, and a liquid hydrogen storage tank. The converted hydrogen enters the flash tank through a filter and valve seven. The bottom of the flash tank is provided with a liquid phase outlet, which is connected to valve nine and the liquid hydrogen storage tank in sequence through a pipeline. The built-in subcooler reduces heat loss and improves the quality of liquid hydrogen.

[0014] The gas recovery and circulation system includes: the gas phase outlets at the top of the atmospheric pressure hydrogen flash tank and the liquid hydrogen storage tank are connected to the inlet of the BOG reheater via pipelines; the outlet of the BOG reheater is connected to the inlet of the low-pressure hydrogen compressor, or to the inlet of the regenerative channel of the pre-cooling box, to achieve cold energy recovery and recycling. Waste cold is utilized in a cascade manner through the reheater or pre-cooling box.

[0015] Furthermore, the liquid hydrogen subcooler is placed inside the atmospheric pressure hydrogen flash tank to form a liquid immersion heat exchanger, or placed outside the atmospheric pressure hydrogen flash tank and configured as a plate heat exchanger structure.

[0016] Furthermore, the three-stage expander, the two-stage expander, and the one-stage expander are respectively linked to the corresponding three-stage booster, the two-stage booster, and the one-stage booster via mechanical couplings; the outlet of each booster is connected to the corresponding booster cooler, and the outlet of the booster cooler is connected to the inlet of the high-pressure hydrogen compressor via a pipeline to realize the recovery of expansion work.

[0017] Furthermore, the BOG reheater is eliminated, and the flash gas directly enters the regenerative channel of the pre-cooling box from the atmospheric pressure hydrogen flash tank. After completing the residual heat recovery, it is connected to the inlet of the low-pressure hydrogen compressor. This simplifies the system structure while maintaining the efficiency of heat recovery.

[0018] Furthermore, the throttling cold hydrogen path in the second loop is cancelled, valve five is removed, and the medium-pressure liquid hydrogen throttling branch in each stage of the heat exchanger does not have a dedicated cold hydrogen channel. The flash gas passes sequentially through the low-pressure hydrogen compressor, valve eleven, medium-pressure hydrogen compressor, valve twelve, and high-pressure hydrogen compressor, and is then incorporated into the raw material hydrogen path.

[0019] Furthermore, the liquid phase outlet of the circulating hydrogen separator in the third loop is connected to the inlet of the liquid hydrogen subcooler. The liquid hydrogen subcooler has two outlets, which are respectively connected to the atmospheric pressure hydrogen flash tank and the liquid hydrogen storage tank. The corresponding outlets are equipped with valve eight and valve nine to control the flow direction of the subcooled secondary hydrogen, thereby realizing the three-loop refrigeration of the entire secondary hydrogen.

[0020] Furthermore, the raw material hydrogen path is also equipped with a circulating hydrogen buffer tank and an oxygen analyzer to stabilize flow fluctuations and monitor hydrogen purity online.

[0021] Furthermore, the low-pressure hydrogen compressor, medium-pressure hydrogen compressor, and high-pressure hydrogen compressor can be one or more combinations of piston, screw, and centrifugal compressors. The low-pressure hydrogen compressor and medium-pressure hydrogen compressor can be set up separately as two units, or they can be integrated into one compressor.

[0022] Furthermore, valves one, two, and three, along with a circulating hydrogen buffer tank, are provided between the inlet and outlet of the high-pressure hydrogen compressor to regulate the inlet and outlet pressures.

[0023] Furthermore, the primary expander, secondary expander, and tertiary expander can be integrated into two units connected in series or set up as three units connected in series, or they can be multiple units connected in series or multiple units connected in parallel. Their bearings can be gas-suspended, magnetically suspended, or oil-bearing, and their braking methods can be oil pumps, fans, compressors, or generators.

[0024] Furthermore, the primary heat exchanger, secondary heat exchanger, tertiary heat exchanger, and quaternary heat exchanger can be integrated into one or two units connected in series, or they can be set up as four units connected in series.

[0025] Furthermore, before passing through the secondary hydrogen converter, the raw material hydrogen gas sequentially passes through channels in four heat exchangers: a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, and a quaternary heat exchanger. These channels are filled with catalysts for secondary hydrogen conversion, and heat exchange and secondary hydrogen conversion are carried out simultaneously. Finally, it undergoes a final stage of adiabatic secondary hydrogen conversion in the secondary hydrogen converter.

[0026] Furthermore, the filter is equipped with a resistance detection instrument, which can be one or two connected in parallel, with a filtration accuracy between 10 and 40 μm.

[0027] The hydrogen cryogenic three-loop refrigeration device described in this utility model has the following beneficial effects:

[0028] (1) Low-cost hydrogen produced on-site is used as the cryogenic refrigerant, resulting in low refrigerant cost.

[0029] (2) A hydrogen cryogenic three-loop refrigeration cycle is adopted. Each loop provides the corresponding grade of cooling capacity for hydrogen liquefaction, reducing the throttling flash evaporation while fully matching the hot and cold streams, reducing the heat exchange temperature difference, and significantly reducing the energy consumption of hydrogen liquefaction.

[0030] (3) Flash vapor is recovered through a vaporizer or pre-cooling box, returned to the circulating hydrogen compressor for pressurization, and then merged into the raw material hydrogen pipeline through a valve to realize flash vapor recovery and reliquefaction, thereby reducing project investment and improving economic benefits. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the present invention;

[0033] Figure 2 This is a schematic diagram of Embodiment 2 of the present invention;

[0034] Figure 3 This is a schematic diagram of Embodiment 3 of this utility model;

[0035] Figure 4 This is a schematic diagram of Embodiment 4 of this utility model;

[0036] Figure 5 This is a schematic diagram of Embodiment 5 of this utility model;

[0037] Figure 6 This is a schematic diagram of Embodiment Six of this utility model;

[0038] In the diagram, 101-Low-pressure hydrogen compressor, 102-Medium-pressure hydrogen compressor, 103-High-pressure hydrogen compressor, 104-First-stage expander, 105-Second-stage expander, 106-Third-stage expander, 107-First-stage booster compressor, 108-Second-stage booster compressor, 109-Third-stage booster compressor, 201-First-stage heat exchanger, 202-Second-stage heat exchanger, 203-Third-stage heat exchanger, 204-Fourth-stage heat exchanger, 205-Low-pressure hydrogen cooler, 206-Medium-pressure hydrogen cooler, 207-High-pressure hydrogen cooler, 208-BOG reheater, 210-First-stage booster cooler, 211-Second-stage booster cooler, 21... 2-Three-stage pressurized cooler, 301-Pre-cooling cold box, 302-Atmospheric pressure hydrogen flash tank, 303-Circulating hydrogen separator, 304-Liquid hydrogen storage tank, 305-Liquid hydrogen subcooler, 306-Circulating hydrogen buffer tank, 307-External plate heat exchanger, 401-Neo-Parhydrogen converter, 402-Filter, 403-Oxygen analyzer, 501-Valve 1, 502-Valve 2, 503-Valve 3, 504-Valve 4, 505-Valve 5, 506-Valve 6, 507-Valve 7, 508-Valve 8, 509-Valve 9, 510-Valve 10, 511-Valve 11, 512-Valve 12. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0041] Example 1:

[0042] like Figure 1 As shown, this embodiment provides a hydrogen cryogenic precooling device, mainly comprising: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, a high-pressure hydrogen compressor 103, a first-stage expander 104, a second-stage expander 105, and a third-stage expander 106; a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, and a fourth-stage heat exchanger 204; a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, and a high-pressure hydrogen cooler 207; a BOG reheater 208; and a liquid hydrogen subcooler 30. 5; Pre-cooling cold box 301, circulating hydrogen separator 303, atmospheric pressure hydrogen flash evaporator 302, liquid hydrogen storage tank 304, circulating hydrogen buffer tank 306; ortho-hydrogen converter 401, filter 402, oxygen analyzer 403; and ten key valves: valve 1 501, valve 2 502, valve 3 503, valve 4 504, valve 5 505, valve 6 506, valve 7 507, valve 8 508, valve 9 509, and valve 10 510, which respectively control the flow and throttling functions of each key branch.

[0043] During operation, the feedstock hydrogen first enters the pre-cooling box 301 through pipelines for initial cooling. After further deep cooling via the first-stage heat exchanger 201 to the fourth-stage heat exchanger 204, the temperature drops to the range required for liquid hydrogen conversion (-243.15℃ and below). At this point, the cryogenic hydrogen enters the ortho-parahydrogen converter 401, where a catalyst partially converts the ortho-hydrogen into para-hydrogen, improving its cryogenic thermodynamic stability.

[0044] The converted hydrogen undergoes further heat exchange in another channel of the four-stage heat exchanger 204, then passes through filter 402 to remove any entrained oxygen crystal particles. It then enters the atmospheric pressure hydrogen flash tank 302 through valve 507 for gas-liquid separation. The separated liquid hydrogen is further cooled to -251°C or lower by the liquid hydrogen subcooler 305 before entering the liquid hydrogen storage tank 304 as product liquid hydrogen. The gaseous hydrogen produced by flash evaporation is introduced into the BOG reheater 208 for heat exchange, and then returns to the inlet of the low-pressure hydrogen compressor 101, re-entering the refrigeration cycle system.

[0045] The core three-loop refrigeration structure of this device is as follows:

[0046] First circuit

[0047] High-pressure hydrogen gas is compressed by high-pressure hydrogen compressor 103 and initially cooled in pre-cooling box 301. It then sequentially enters primary heat exchanger 201, primary expander 104, secondary heat exchanger 202, secondary expander 105, tertiary heat exchanger 203, and tertiary expander 106, undergoing adiabatic expansion and cooling at each stage to produce cryogenic hydrogen gas, providing cryogenic cooling capacity to multiple heat exchangers. This portion of the gas is ultimately returned via pipeline to merge with the medium-pressure cycle, forming a cold energy recovery path.

[0048] Second circuit

[0049] In the first loop, a portion of the high-pressure hydrogen gas, after leaving the pre-cooling box 301, is diverted into another pipeline and sequentially passes through the primary heat exchanger 201, the secondary heat exchanger 202, and the tertiary heat exchanger 203. Finally, after being cooled by the quaternary heat exchanger 204, it enters the circulating hydrogen separator 303 via valve 506. The separated gas phase sequentially passes through the tertiary heat exchanger 203, the secondary heat exchanger 202, and the primary heat exchanger 201, while the liquid phase sequentially passes through the quaternary heat exchanger 204, the tertiary heat exchanger 203, the secondary heat exchanger 202, and the primary heat exchanger 201 for heat exchange before re-entering the medium-pressure hydrogen compressor 102 for the next compression and cooling cycle.

[0050] Third circuit

[0051] In the second loop, a portion of the liquid phase separated from the circulating hydrogen separator 303 enters the atmospheric pressure hydrogen flash tank 302 through valve 8 508, and then passes through valve 9 509, liquid hydrogen storage tank 304, and BOG reheater 208 in sequence before returning to the inlet of the low-pressure hydrogen compressor 101 to complete the release of cold energy and flash vapor treatment.

[0052] Through the above three-loop cooling scheme, the system can achieve precise matching and cooling of multiple heat exchange sections, improve heat exchange efficiency, minimize flash evaporation loss during throttling, reduce cold capacity redundancy, and optimize energy consumption.

[0053] In addition, in the flash vapor recovery path, after preheating by the BOG reheater 208, the flash vapor is directly fed into the suction port of the low-pressure compressor 101, eliminating the need for an additional flash vapor compressor, thereby reducing system investment and operating costs.

[0054] This device uses hydrogen itself as a refrigerant, which has the advantages of low refrigerant cost, closed circulation system, high efficiency and safety.

[0055] Example 2:

[0056] like Figure 2As shown, this embodiment is an optimized solution based on Embodiment 1. Its core structure is similar to that of Embodiment 1, mainly including: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, and a high-pressure hydrogen compressor 103; a first-stage expander 104, a second-stage expander 105, and a third-stage expander 106; a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, and a fourth-stage heat exchanger 204; a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, and a high-pressure hydrogen cooler 207. BOG reheater 208; precooling box 301, circulating hydrogen separator 303, atmospheric pressure hydrogen flash evaporator 302, liquid hydrogen storage tank 304, circulating hydrogen buffer tank 306; ortho- and para-hydrogen converter 401, filter 402, oxygen analyzer 403; and several valves used in the control system, including valve 1 501, valve 2 502, valve 3 503, valve 4 504, valve 5 505, valve 6 506, valve 7 507, valve 8 508, valve 9 509, and valve 10 510.

[0057] Compared to Embodiment 1, the main difference in this embodiment lies in the optimized structure and arrangement of the liquid hydrogen subcooler 305. In the original embodiment, the liquid hydrogen subcooler was located inside the atmospheric pressure hydrogen flash tank 302, and heat exchange was performed by liquid immersion. In this embodiment, the liquid hydrogen subcooler 305 is independently configured as an external plate heat exchanger 307, and is directly connected to the liquid hydrogen storage tank 304 through heat exchange pipelines.

[0058] In the process flow, the cooled cryogenic hydrogen gas, after passing through a four-stage heat exchanger 204 and a neutral-to-hydrogen converter 401, is filtered by a filter 402 to remove particulate impurities. It then enters an atmospheric pressure hydrogen flash tank 302 through valve 507 for gas-liquid separation. The resulting liquid phase enters an external liquid hydrogen subcooler 305 for further cooling before finally flowing into a liquid hydrogen storage tank 304 as the product liquid hydrogen output. The flash gas, after recovering its cooling capacity through a BOG reheater 208, returns to the inlet of the low-pressure compressor 101 to re-enter the refrigeration cycle.

[0059] This embodiment retains the complete three-loop structure design. The first loop is based on high-pressure hydrogen expansion and cooling, the second loop uses medium-pressure throttling for cooling, and the third loop utilizes low-pressure hydrogen circulation to enhance heat exchange capacity in the low-temperature section. Through local structural improvements, maintenance convenience is enhanced without affecting the system's cooling performance, making it suitable for liquid hydrogen production systems with high maintenance frequency or requiring modular design.

[0060] Example 3:

[0061] like Figure 3As shown, this embodiment further optimizes the energy utilization method based on Embodiment 1 by adding an expansion work recovery structure. It mainly includes: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, a high-pressure hydrogen compressor 103, a first-stage expander 104, a second-stage expander 105, a third-stage expander 106, a first-stage booster compressor 107, a second-stage booster compressor 108, a third-stage booster compressor 109, a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, a fourth-stage heat exchanger 204, a first-stage booster cooler 210, and a second-stage booster cooler... The system includes: a three-stage pressurized cooler 212, a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, a high-pressure hydrogen cooler 207, a pre-cooling box 301, an atmospheric pressure hydrogen flash evaporator 302, a circulating hydrogen separator 303, a liquid hydrogen storage tank 304, a liquid hydrogen subcooler 305, a circulating hydrogen buffer tank 306, a neutral hydrogen converter 401, a filter 402, an oxygen analyzer 403, and several throttling valves and connecting pipelines.

[0062] Specifically, the raw hydrogen gas first enters the first channel of the pre-cooling box 301 through a pipeline. After initial heat exchange and cooling with the return hydrogen gas, it enters the first channels of the primary heat exchanger 201, secondary heat exchanger 202, tertiary heat exchanger 203, and quaternary heat exchanger 204 for further cooling. The cooled high-pressure hydrogen gas is divided into multiple streams, one of which flows sequentially into the primary expander 104, secondary expander 105, and tertiary expander 106 for adiabatic expansion, obtaining cryogenic hydrogen gas in different temperature zones to provide low-temperature cooling for each stage of the heat exchanger.

[0063] In this embodiment, all three expanders are mechanically coupled to their respective booster compressors to form an expansion work recovery structure. Specifically, the power shaft of the first-stage expander 104 is coupled to the first-stage booster compressor 107, and the outlet of the first-stage booster compressor 107 is connected to the first-stage booster cooler 210. Similarly, the second-stage expander 105 is coupled to the second-stage booster compressor 108, and the outlet of the second-stage booster compressor 108 is connected to the second-stage booster cooler 211. The third-stage expander 106 is coupled to the third-stage booster compressor 109, and the outlet of the third-stage booster compressor 109 is connected to the third-stage booster cooler 212. The pressurized gas then returns to the high-pressure hydrogen compressor 103 after passing through the first-stage booster cooler 210.

[0064] The compressed gas originates from the heat exchange outlet sections of the heat exchangers at each stage and the pre-cooling box, namely medium-pressure reflux hydrogen. After releasing its cooling capacity, the gas recovers and reuses its energy through the three sets of "booster compressor-cooler-expander" paths mentioned above, thereby effectively reducing compression power consumption and improving system energy efficiency.

[0065] It should be noted that the three-loop refrigeration structure remains unchanged in this embodiment, with each loop still consisting of high-pressure expansion cooling, medium-pressure throttling cooling, and low-pressure flash vapor recovery cooling. By introducing a mechanical energy recovery structure, the device achieves a high energy recovery rate without significantly increasing volume or control complexity, making it suitable for large-scale liquid hydrogen production systems with stringent energy efficiency requirements.

[0066] Example 4:

[0067] like Figure 4 As shown, this embodiment adjusts the flash gas recovery method based on Embodiment 1, eliminating the BOG reheater structure and simplifying the process path while integrating cold energy reuse. The device mainly includes: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, a high-pressure hydrogen compressor 103, a first-stage expander 104, a second-stage expander 105, a third-stage expander 106, a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, a fourth-stage heat exchanger 204, a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, a high-pressure hydrogen cooler 207, a pre-cooling box 301, an atmospheric pressure hydrogen flash tank 302, a circulating hydrogen separator 303, a liquid hydrogen storage tank 304, a liquid hydrogen subcooler 305, a circulating hydrogen buffer tank 306, a neutral hydrogen converter 401, a filter 402, an oxygen analyzer 403, and several throttling valves and connecting pipelines.

[0068] Specifically, the raw material hydrogen first enters the pre-cooling box 301 through pipelines for initial heat exchange, and then sequentially enters the primary heat exchanger 201, secondary heat exchanger 202, tertiary heat exchanger 203, and quaternary heat exchanger 204 for further cooling. The cooled high-pressure hydrogen then enters the multi-stage expander for adiabatic expansion to obtain low-temperature hydrogen, forming the first loop of the refrigeration cycle.

[0069] The expanded hydrogen flows back to the reheating channel of the heat exchanger to provide cooling for the preceding hydrogen. It then merges with the circulating hydrogen from the second and third loops. After gas-liquid separation in the separator 303, the liquid phase enters the pipeline to supply the fourth-stage heat exchanger 204 and finally flows into the liquid hydrogen storage tank 304 as the product output.

[0070] In this embodiment, the atmospheric pressure hydrogen flash tank 302 is used to receive the BOG formed by flashing from the liquid hydrogen storage tank 304. Unlike embodiment one, the flash gas no longer enters the BOG reheater for heat exchange; instead, it is directly fed into the regenerator channel of the pre-cooling box 301, where it undergoes countercurrent heat exchange with the feed hydrogen. The remaining heat is recovered and used to improve the cooling efficiency of the feed gas. The flash gas after heat exchange returns to the inlet of the low-pressure hydrogen compressor 101 through a pipeline and re-enters the first loop to participate in the refrigeration cycle.

[0071] This design eliminates the need for a dedicated BOG reheater, reducing the number of large cryogenic heat exchangers and simplifying the process flow and equipment layout. Simultaneously, by introducing flash vapor into the pre-cooling box for waste heat recovery, the system reduces the number of physical devices and installation volume while maintaining overall thermal efficiency.

[0072] This structure is suitable for applications with limited space or high requirements for system integration, such as modular liquid hydrogen skid-mounted equipment and small liquid hydrogen stations, while also having significant advantages in terms of equipment investment and maintenance costs.

[0073] Example 5:

[0074] like Figure 5 As shown, this embodiment, based on Embodiment 1, improves the structure of the flash gas recovery path by employing a multi-stage compression mechanism to achieve flash gas reliquefaction and removing the throttling branch channel in the heat exchanger structure to form a new independent loop path. The device mainly includes: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, a high-pressure hydrogen compressor 103, a first-stage expander 104, a second-stage expander 105, a third-stage expander 106, a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, a fourth-stage heat exchanger 204, a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, a high-pressure hydrogen cooler 207, a pre-cooling box 301, and an atmospheric pressure hydrogen flash tank. Components including: 302, circulating hydrogen separator; 303, liquid hydrogen storage tank; 304, liquid hydrogen subcooler; 305, circulating hydrogen buffer tank; 306, ortho-hydrogen converter; 401, filter; 402, oxygen analyzer; and valves 501, 502, 503, 504, 506, 507, 508, 509, 510, 511, and 512.

[0075] Specifically, the raw material hydrogen gas first passes through the raw material gas path sequentially through the pre-cooling box 301, the first-stage heat exchanger 201, the second-stage heat exchanger 202, the third-stage heat exchanger 203, and the fourth-stage heat exchanger 204, undergoing progressive cooling. The cooled hydrogen gas then enters the three-stage expander, where it undergoes adiabatic expansion to form multi-temperature zone cryogenic hydrogen gas, which serves as a cold source and flows back to the refrigerant side channels of the aforementioned heat exchangers, providing cooling for the raw material gas.

[0076] Unlike Embodiment 1, this embodiment eliminates the branch path and its corresponding structure used for throttling medium-pressure liquid hydrogen in the original system, including valve 505 for throttling control, and cold hydrogen channels used for throttling liquid hydrogen return in the first-stage heat exchanger 201, second-stage heat exchanger 202, third-stage heat exchanger 203 and fourth-stage heat exchanger 204.

[0077] To achieve closed-loop refrigeration and flash vapor reuse, new valves 11 (511) and 12 (512) and alternative paths were installed, resulting in three independent flow lines in the cold hydrogen circulation path. These flow lines are respectively connected to low-pressure hydrogen compressor 101, medium-pressure hydrogen compressor 102, and high-pressure hydrogen compressor 103 to form low, medium, and high-pressure loops.

[0078] Specifically, the gaseous hydrogen (flash vapor) from the top of the atmospheric hydrogen flash tank 302 first enters the low-pressure hydrogen compressor 101 for compression, then enters valve 11 511 via a pipeline, and enters the medium-pressure hydrogen compressor 102 for further pressurization. Subsequently, it enters the high-pressure hydrogen compressor 103 through valve 12 512 to complete the third compression, and finally merges into the main feedstock hydrogen pipeline, where it combines with the newly entered hydrogen and participates in the liquefaction process again.

[0079] This design not only reduces the number of throttling channels in the heat exchanger, but also allows flash vapor to be recycled back to the feed gas through three-stage compression, avoiding direct discharge of flash vapor and improving the liquid hydrogen yield. Furthermore, the flow rate can be dynamically adjusted by controlling the valves, enhancing the flexibility and response speed of the system operation.

[0080] This embodiment is applicable to scenarios requiring large-scale continuous production of liquid hydrogen, and is particularly suitable for large-scale liquefaction plants and long-distance transportation stations with strict control over hydrogen recovery rate and energy consumption indicators.

[0081] Example 6:

[0082] like Figure 6 As shown, this embodiment further optimizes the hydrogen path structure of the third loop based on embodiment one, realizing three-loop closed-loop refrigeration with all secondary hydrogen involved, aiming to improve the low-temperature stability of the system and further reduce energy consumption.

[0083] The device mainly includes: a low-pressure hydrogen compressor 101, a medium-pressure hydrogen compressor 102, a high-pressure hydrogen compressor 103, a first-stage expander 104, a second-stage expander 105, a third-stage expander 106, a first-stage heat exchanger 201, a second-stage heat exchanger 202, a third-stage heat exchanger 203, a fourth-stage heat exchanger 204, a low-pressure hydrogen cooler 205, a medium-pressure hydrogen cooler 206, a high-pressure hydrogen cooler 207, a BOG reheater 208, and a preheater. The equipment includes a cold box 301, an atmospheric pressure hydrogen flash evaporator 302, a circulating hydrogen separator 303, a liquid hydrogen storage tank 304, a liquid hydrogen subcooler 305, a circulating hydrogen buffer tank 306, a neutral hydrogen converter 401, a filter 402, an oxygen analyzer 403, and valves 1-501, 2-502, 3-503, 4-504, 5-505, 6-506, 7-507, 8-508, and 9-509.

[0084] Compared to Example 1, firstly, valve 510 is eliminated, and the feed gas branch originally controlled by this valve is merged into a unified path; secondly, the flash vapor return path in the third loop is adjusted as follows: the pipeline containing valve 507 is directly connected to the circulating hydrogen separator 303, and the output end of the circulating hydrogen separator 303 is directly connected to the liquid hydrogen subcooler 305. The output end of the liquid hydrogen subcooler 305 has two channels, controlled by valves 509 and 508 respectively. Hydrogen is injected into the atmospheric pressure flash tank 302 via valve 508 and into the liquid hydrogen storage tank 304 via valve 509. This achieves full-range hydrogen three-loop refrigeration, reducing the unit's energy consumption.

[0085] The above embodiments describe the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Modifications and variations made by those skilled in the art without departing from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. A device for hydrogen deep cryogenic three-loop refrigeration, characterized in that, The system includes a raw hydrogen supply system, a neutral hydrogen conversion system, a three-loop hydrogen refrigeration system, a liquid hydrogen collection and subcooling system, and a gas recovery and circulation system. The raw hydrogen supply system comprises a pre-cooling box (301), a primary heat exchanger (201), a secondary heat exchanger (202), a tertiary heat exchanger (203), and a quaternary heat exchanger (204) connected in sequence. The raw hydrogen undergoes progressive heat exchange and cooling in multiple heat exchangers to form a low-temperature hydrogen channel. The neutral hydrogen conversion system includes a filter (402) and a neutral hydrogen converter (401), located between the outlet of the quaternary heat exchanger (204) and the liquid hydrogen collection system. The outlet of the low-temperature hydrogen channel is connected to the inlet via the neutral hydrogen converter (401). 402) The outlet is connected to the inlet of the atmospheric pressure hydrogen flash tank (302) to complete the hydrogen structure conversion and flash separation; the three-loop hydrogen refrigeration system includes: the first loop: the outlet of the high-pressure hydrogen compressor (103) is connected in sequence to the inlet of the first-stage heat exchanger (201), the inlet of the first-stage expander (104), the second-stage heat exchanger (202), the second-stage expander (105), the third-stage heat exchanger (203), and the third-stage expander (106), forming a step-by-step adiabatic expansion path. After expansion, the hydrogen flows back to the heat recovery channel of each stage of heat exchanger in sequence, and then merges with the refrigerant of other loops; the second loop: the high-pressure liquid hydrogen enters the circulating hydrogen separator (303) after passing through valve six (506). The separated liquid phase and gas phase pass through the third-stage heat exchanger (203) in sequence. The intermediate cooling channel of the secondary heat exchanger (202) and the primary heat exchanger (201) completes the release of cold energy in the medium temperature zone and then flows back to the inlet of the medium-pressure hydrogen compressor (102) to form a closed-loop cooling path; the third loop: another stream of liquid hydrogen separated from the circulating hydrogen separator (303) enters the atmospheric pressure hydrogen flash tank (302) after being throttled by valve eight (508), and then passes through valve nine (509), liquid hydrogen storage tank (304), and BOG reheater (208) in sequence to return to the inlet of the low-pressure hydrogen compressor (101) to form a gas recovery path; the liquid hydrogen collection and subcooling system includes: an atmospheric pressure hydrogen flash tank (302), a liquid hydrogen subcooler (305) and a liquid hydrogen storage tank (304), and the hydrogen after the hydrogen structure conversion is processed by The filter (402) enters the atmospheric pressure hydrogen flash tank (302); the atmospheric pressure hydrogen flash tank (302) is provided with a liquid phase outlet at the bottom, which is connected to valve nine (509) and the liquid hydrogen storage tank (304) in sequence through a pipeline; the gas recovery and circulation system includes: the gas phase outlets at the top of the atmospheric pressure hydrogen flash tank (302) and the liquid hydrogen storage tank (304) are connected to the inlet of the BOG reheater (208) after being merged by a pipeline, and the outlet of the BOG reheater (208) is connected to the inlet of the low pressure hydrogen compressor (101), or connected to the inlet of the regenerating channel of the pre-cooling cold box (301), and the cold energy is recovered and recycled in sequence through the low pressure hydrogen compressor (101), the medium pressure hydrogen compressor (102), and the high pressure hydrogen compressor (103).

2. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The liquid hydrogen subcooler (305) is placed inside the atmospheric pressure hydrogen flash tank (302) to form a liquid immersion heat exchanger, or it is placed outside the atmospheric pressure hydrogen flash tank (302) and configured as a plate heat exchanger structure.

3. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The three-stage expander (106), the two-stage expander (105), and the one-stage expander (104) are respectively linked to the corresponding three-stage booster (109), the two-stage booster (108), and the one-stage booster (107) via mechanical couplings; the outlet of each booster is connected to the corresponding booster cooler, and the outlet of the booster cooler is connected to the inlet of the high-pressure hydrogen compressor (103) through a pipeline to realize the recovery of expansion work.

4. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The BOG reheater (208) is removed, and the flash gas in the atmospheric pressure hydrogen flash tank (302) directly enters the regeneration channel of the pre-cooling cold box (301), and after the residual cold is recovered, it is connected to the inlet of the low pressure hydrogen compressor (101).

5. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The throttling cold hydrogen path in the second loop is cancelled, valve five (505) is removed, and the medium-pressure liquid hydrogen throttling branch in each heat exchanger does not have a dedicated cold hydrogen channel. The flash gas output from the BOG reheater (208) passes through the low-pressure hydrogen compressor (101), valve eleven (511), medium-pressure hydrogen compressor (102), valve twelve (512), and high-pressure hydrogen compressor (103) in sequence and is incorporated into the raw material hydrogen path.

6. The apparatus for hydrogen cryogenic triple-loop refrigeration according to claim 1, characterized in that, The liquid phase outlet of the circulating hydrogen separator (303) in the third loop is connected to the inlet of the liquid hydrogen subcooler (305). The liquid hydrogen subcooler (305) is provided with two outlets, which are respectively connected to the atmospheric pressure hydrogen flash tank (302) and the liquid hydrogen storage tank (304). The corresponding outlets are provided with valve eight (508) and valve nine (509) to control the flow direction of the subcooled secondary hydrogen and realize the three-loop refrigeration of the entire secondary hydrogen.

7. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 5, characterized in that, The raw material hydrogen path is also equipped with a circulating hydrogen buffer tank (306) and an oxygen analyzer (403) to stabilize flow fluctuations and monitor hydrogen purity online.

8. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The low-pressure hydrogen compressor (101), medium-pressure hydrogen compressor (102), and high-pressure hydrogen compressor (103) can be one or more combinations of piston, screw, and centrifugal compressors. The low-pressure hydrogen compressor (101) and medium-pressure hydrogen compressor (102) can be set up separately as two units or integrated into one compressor.

9. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The high-pressure hydrogen compressor (103) is equipped with valve one (501), valve two (502), valve three (503), and circulating hydrogen buffer tank (306) between its inlet and outlet to achieve inlet and outlet pressure regulation.

10. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The primary expander (104), secondary expander (105), and tertiary expander (106) are integrated into a multi-unit series or multi-unit parallel structure. Their bearings can be gas-suspended, magnetically suspended, or oil-bearing, and their braking methods can be oil pumps, fans, compressors, or generators.

11. The device for hydrogen deep cryogenic three-loop refrigeration according to claim 1, characterized in that, The primary heat exchanger (201), secondary heat exchanger (202), tertiary heat exchanger (203), and quaternary heat exchanger (204) can be integrated into one or two units connected in series, or they can be set up as four units connected in series.

12. The apparatus for hydrogen deep cryogenic three loop refrigeration of claim 1, wherein, Before passing through the secondary hydrogen converter (401), the raw material hydrogen gas passes through the channels in the four heat exchangers: the primary heat exchanger (201), the secondary heat exchanger (202), the tertiary heat exchanger (203), and the quaternary heat exchanger (204). The channels are filled with catalysts for secondary hydrogen conversion, and heat exchange and secondary hydrogen conversion are carried out simultaneously. Finally, it passes through the secondary hydrogen converter (401) for the last stage of adiabatic secondary hydrogen conversion.

13. The apparatus for hydrogen deep cryogenic three loop refrigeration of claim 1, wherein, The filter (402) is equipped with a resistance detection instrument, which can be one or two connected in parallel, with a filtration accuracy between 10 and 40 μm.

Images