A secondary hydrogen conversion device for hydrogen liquefaction

Abstract

This utility model discloses a secondary hydrogen conversion device for hydrogen liquefaction. The device comprises a first secondary hydrogen conversion unit located between multiple input and output terminals of a first main heat exchanger (E100). The output terminal of the first secondary hydrogen conversion unit is connected to an output pipeline, and the input terminal is connected to an input pipeline. One output terminal of the first main heat exchanger (E100) is connected to a second main heat exchanger (E200). A second secondary hydrogen conversion unit is located between one or more input and output terminals of the second main heat exchanger (E200). The output terminal of the second secondary hydrogen conversion unit is connected to an output pipeline, which includes a liquid hydrogen pipeline and a venting pipeline. The input pipeline includes a nitrogen pipeline and a hydrogen pipeline. This utility model features a simple secondary hydrogen conversion process, low operating costs, and ease of operation, achieving a secondary hydrogen concentration ≥95% after conversion.

Description

Technical Field

[0001] This utility model relates to the field of ortho- and para-hydrogen conversion technology, and in particular to an ortho- and para-hydrogen conversion device for hydrogen liquefaction. Background Technology

[0002] Liquid hydrogen is easy to store and has advantages such as high expansion rate and high energy density after vaporization, making it one of the important methods for hydrogen energy use and storage. Depending on the rotation direction of the hydrogen atoms, hydrogen molecules exist in two forms: orthohydrogen and parahydrogen. During hydrogen liquefaction, as the hydrogen temperature decreases, orthohydrogen spontaneously converts to parahydrogen, and the conversion rate is very slow. This conversion releases a large amount of heat, causing the liquid hydrogen in the storage tank to vaporize, resulting in a significant increase in BOG flash evaporation and increased hydrogen liquefaction energy consumption. Therefore, it is necessary to add an orthohydrogen and parahydrogen catalytic conversion process during hydrogen liquefaction to accelerate the conversion rate and reduce BOG flash evaporation in the liquid hydrogen storage tank.

[0003] Currently, there is limited research on the conversion process of ortho- and para-hydrogen in domestic liquid hydrogen plants. Chinese patent CN 109028755 A discloses an ortho- and para-hydrogen conversion process for liquid hydrogen production, employing a two-stage isothermal reactor. The first stage is used for gas-phase conversion, with liquid nitrogen as the cooling source for heat exchange; the second stage is used for liquid-phase conversion, with liquid hydrogen as the cooling source for heat exchange. However, this process requires an external liquid cooling source, has relatively high overall energy consumption, a complex reactor structure, and lacks a description of an activation method. Chinese patent CN112361712 A discloses a hydrogen liquefaction device using a helium refrigeration cycle system, employing a two-stage isothermal reactor and a two-stage adiabatic reactor. This process also suffers from the drawbacks of requiring an external liquid cooling source, a complex reactor structure, high overall energy consumption, and lacks a description of an activation method. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hydrogen liquefaction device and conversion and activation method that is widely applicable, energy-efficient, and highly operable.

[0005] This utility model is achieved using the following technical solution: a secondary hydrogen conversion device for hydrogen liquefaction, comprising a first main heat exchanger, a second main heat exchanger, a first secondary hydrogen conversion unit, and a second secondary hydrogen conversion unit. The first secondary hydrogen conversion unit is disposed between multiple input and output ends of the first main heat exchanger. The output end of the first secondary hydrogen conversion unit is connected to an output pipeline, and the input end of the first secondary hydrogen conversion unit is connected to an input pipeline. One output end of the first main heat exchanger is connected to the second main heat exchanger. The second secondary hydrogen conversion unit is disposed between one or more input and output ends of the second main heat exchanger. The output end of the second secondary hydrogen conversion unit is connected to an output pipeline, which includes a liquid hydrogen pipeline and a venting pipeline. The input pipeline includes a nitrogen pipeline and a hydrogen pipeline.

[0006] Furthermore, the first main heat exchanger is provided with a first cold source channel, a raw material hydrogen precooling channel, a first raw material hydrogen cooling channel, and a second raw material hydrogen cooling channel. The input end of the raw material hydrogen precooling channel is connected to the raw material hydrogen pipeline, and the output end of the raw material hydrogen precooling channel and the first raw material hydrogen cooling channel are connected to the first neutral hydrogen conversion unit. The output end of the first neutral hydrogen conversion unit is connected to the input ends of the first raw material hydrogen cooling channel and the second raw material hydrogen cooling channel, respectively.

[0007] Furthermore, the first secondary hydrogen conversion unit includes a low-temperature adsorber, a primary secondary hydrogen converter, and a secondary secondary hydrogen converter. The output end of the raw material hydrogen precooling channel is connected to the input end of the low-temperature adsorber. The output end of the low-temperature adsorber is connected to the input ends of both the primary and secondary secondary hydrogen converters. The output end of the primary secondary hydrogen converter is connected to the input ends of both the first and second raw material hydrogen cooling channels, and is also connected to an output pipeline. The output end of the secondary secondary hydrogen converter is connected to the input ends of both the second and first raw material hydrogen cooling channels, and is also connected to an output pipeline.

[0008] Furthermore, the second main heat exchanger is equipped with a raw material hydrogen recooling channel, a first hydrogen cooling channel, a second hydrogen cooling channel, a third hydrogen cooling channel, a fourth hydrogen cooling channel, and a second cold source channel. The input end of the raw material hydrogen recooling channel is connected to the output end of the first main heat exchanger and the activated nitrogen and hydrogen pipelines, respectively. The output ends of the raw material hydrogen recooling channel, the first hydrogen cooling channel, the second hydrogen cooling channel, and the third hydrogen cooling channel are all connected to the input end of the second neutral hydrogen conversion unit. The output end of the second neutral hydrogen conversion unit is connected to the input ends of the first hydrogen cooling channel, the second hydrogen cooling channel, the third hydrogen cooling channel, and the fourth hydrogen cooling channel, respectively. The output end of the fourth hydrogen cooling channel is connected to the output pipeline.

[0009] Furthermore, the second secondary hydrogen conversion unit includes a secondary hydrogen converter, a tertiary hydrogen converter, a quaternary hydrogen converter, and a quinary hydrogen converter, which are sequentially arranged between the feed hydrogen recooling channel, the first hydrogen cooling channel, the second hydrogen cooling channel, the third hydrogen cooling channel, and the fourth hydrogen cooling channel.

[0010] Furthermore, the second main heat exchanger is provided with a raw material hydrogen recooling channel, a first hydrogen cooling channel, a second hydrogen cooling channel, a third hydrogen cooling channel, a fourth hydrogen cooling channel, and a second cold source channel. The input end of the raw material hydrogen recooling channel is connected to the output end of the first main heat exchanger and the activated nitrogen and hydrogen pipelines, respectively. The raw material hydrogen recooling channel, the first hydrogen cooling channel, the second hydrogen cooling channel, and the third hydrogen cooling channel are connected in sequence. A second positive and negative hydrogen conversion unit is provided between the third hydrogen cooling channel and the fourth hydrogen cooling channel.

[0011] Furthermore, the second secondary hydrogen conversion unit includes a five-stage secondary hydrogen converter. The input end of the five-stage secondary hydrogen converter is connected to the output end of the third hydrogen cooling channel, and the output end is connected to the input end of the fourth hydrogen cooling channel. In addition, secondary hydrogen catalysts are provided in the feed hydrogen recooling channel, the first hydrogen cooling channel, the second hydrogen cooling channel, the third hydrogen cooling channel, and the fourth hydrogen cooling channel.

[0012] Furthermore, one or more isolation valves are provided on the pipeline between the first main heat exchanger, the second main heat exchanger, the first secondary hydrogen conversion unit, and the second secondary hydrogen conversion unit.

[0013] Furthermore, a regeneration vacuum pump is installed on the venting pipeline; and a nitrogen electric heater is installed on the activated nitrogen pipeline.

[0014] The beneficial effects of this utility model are as follows:

[0015] Compared with the prior art, this invention does not require additional liquid nitrogen or liquid hydrogen consumption, thus significantly reducing energy consumption.

[0016] The present invention provides a simple process for the conversion of positive and negative hydrogen, with low operating costs and easier operation, and the concentration of negative hydrogen after conversion is ≥95%.

[0017] The activation process of this invention adopts a segmented design. The first main heat exchanger and the secondary hydrogen conversion reactor in the first secondary hydrogen conversion unit are isolated activations, which do not affect other equipment and have strong independence. The second main heat exchanger and the second secondary hydrogen conversion unit have two to five stages of secondary hydrogen conversion reactors that are cascaded activations. The number of valves is small, the operability is strong, nitrogen is used as the activation medium and does not damage the catalyst. After activation, the vacuum pump is used for evacuation treatment, resulting in a high activation depth and better safety. Attached Figure Description

[0018] 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. Obviously, 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.

[0019] Figure 1 This is a schematic diagram of the structure of Example 1;

[0020] Figure 2 This is a schematic diagram of the structure of Example 2;

[0021] In the diagram, E100 is the first main heat exchanger, E200 is the second main heat exchanger, A100 is the low-temperature adsorber, RA100-1 is the first-stage secondary hydrogen converter, RA100-2 is the first-stage secondary hydrogen converter, RA200 is the second-stage secondary hydrogen converter, RA300 is the third-stage secondary hydrogen converter, RA400 is the fourth-stage secondary hydrogen converter, RA500 is the fifth-stage secondary hydrogen converter, EH100 is the nitrogen electric heater, P100 is the regeneration vacuum pump, 101 is the first cold source channel, 102 is the feed hydrogen pre-cooling channel, 103 is the first feed hydrogen cooling channel, 104 is the second feed hydrogen cooling channel, 201 is the feed hydrogen re-cooling channel, 202 is the first hydrogen cooling channel, 203 is the second hydrogen cooling channel, 204 is the third hydrogen cooling channel, 205 is the fourth hydrogen cooling channel, and 206 is the second cold source channel. Detailed Implementation

[0022] 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.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] Example 1

[0026] See Figure 1 A hydrogen liquefaction and secondary hydrogen conversion device includes: a first main heat exchanger E100, a low-temperature adsorber A100, a primary secondary hydrogen converter RA100-1, a primary secondary hydrogen converter RA100-2, a nitrogen electric heater EH100, a regeneration vacuum pump P100, a second main heat exchanger E200, a secondary secondary hydrogen converter RA200, a tertiary secondary hydrogen converter RA300, a quaternary secondary hydrogen converter RA400, and a quinary secondary hydrogen converter RA500.

[0027] The first main heat exchanger E100 is equipped with a first cold source channel 101 at 80K, a raw material hydrogen pre-cooling channel 102, a first raw material hydrogen cooling channel 103, and a second raw material hydrogen cooling channel 104. The second main heat exchanger E200 is equipped with a raw material hydrogen re-cooling channel 201, a first hydrogen cooling channel 202, a second hydrogen cooling channel 203, a third hydrogen cooling channel 204, a fourth hydrogen cooling channel 205, and a second cold source channel 206 at 25K.

[0028] The raw material hydrogen pipeline FH11 is connected to the inlet of the raw material hydrogen precooling channel 102. The outlet pipeline FH12 of the raw material hydrogen precooling channel 102 is connected to the inlet of the cryogenic adsorber A100. The outlet pipeline FH13 of the cryogenic adsorber A100 is connected to the inlet of the isolation valve VM11. One outlet of the isolation valve VM11 is connected to the outlet of the isolation valve VM12, and the other outlet is connected to the inlet of the first-stage primary neutral hydrogen converter RA100-1. One outlet pipeline FH14 of the first-stage primary neutral hydrogen converter RA100-1 is connected to the inlet of the isolation valve VM13, and the other outlet is connected to the inlet of the isolation valve VM18. The outlet of the isolation valve VM13 is connected to the inlet of the first raw material gas cooling channel 103. The outlet of the first raw material gas cooling channel 103 is connected to the inlet of the first raw material gas cooling channel 103. Pipeline FH15 is connected to the inlet of isolation valve VM14. One outlet of isolation valve VM14 is connected to the inlet of the primary secondary anisotropic hydrogen converter RA100-2, and the other outlet is connected to the outlet of isolation valve VM17. Pipeline FH16, the outlet of the primary secondary anisotropic hydrogen converter RA100-2, is connected to the inlet of isolation valve VM16, and the other outlet is connected to the inlet of isolation valve VM15. The outlet of isolation valve VM16 is connected to the inlet of the feed gas cooling channel 104. Pipeline FH17, the outlet of the second feed hydrogen cooling channel 104, is connected to the inlet of isolation valve VM22. One outlet of isolation valve VM22 is connected to the inlet of the feed hydrogen recooling channel 201 of the second main heat exchanger E200, and the other outlet is connected to the outlet of isolation valve VM21.

[0029] The outlet pipeline FH21 of the feedstock hydrogen recooling channel 201 is connected to the inlet of the secondary intermediate hydrogen converter RA200. The outlet pipeline FH22 of the secondary intermediate hydrogen converter RA200 is connected to the inlet of the first hydrogen cooling channel 202. The outlet pipeline FH23 of the first hydrogen cooling channel 202 is connected to the inlet of the tertiary intermediate hydrogen converter RA300. The outlet pipeline FH24 of the tertiary intermediate hydrogen converter RA300 is connected to the inlet of the second hydrogen cooling channel 203. The outlet pipeline FH25 of the second hydrogen cooling channel 203 is connected to the fourth intermediate hydrogen converter. The inlet of converter RA400 is connected; the outlet pipeline FH26 of the fourth-stage intermediate hydrogen converter RA400 is connected to the inlet of the third hydrogen cooling channel 204; the outlet pipeline FH27 of the third hydrogen cooling channel 204 is connected to the inlet of the fifth-stage intermediate hydrogen converter RA500; the outlet pipeline FH28 of the fifth-stage intermediate hydrogen converter RA500 is connected to the inlet of the fourth hydrogen cooling channel 205; one outlet pipeline FH29 of the fourth hydrogen cooling channel 205 is connected to the inlet of the isolation valve VM24, and the other outlet pipeline is connected to the inlet of the isolation valve VM23.

[0030] The outlet of isolation valve VM23 is connected to the inlet of vent valve VM26. The outlet of vent valve VM26 is connected to the vent pipeline. The outlet of isolation valve VM24 is connected to the downstream liquid hydrogen pipeline FH29. The activated nitrogen pipeline N11 is connected to the inlet of isolation valve VM19. The outlet of isolation valve VM19 is connected to the inlet of nitrogen electric heater EH100. One branch of the outlet pipeline FH18 of nitrogen electric heater EH100 is connected to the outlet of isolation valve VM27, and the other branch is connected to the inlets of isolation valves VM17, VM12, and VM21. The replacement hydrogen is connected to the inlet of isolation valve VM27. One branch of the outlet pipeline VT11 of isolation valves VM15, VM18, and VM23 is connected to the inlet of isolation valve VM25, and the other branch is connected to the inlet of isolation valve VM26. The outlet of isolation valve VM25 is connected to the inlet of regeneration vacuum pump P100, and the outlet of regeneration vacuum pump P100 is connected to the vent pipeline.

[0031] In this embodiment, the first main heat exchanger E100 and the second main heat exchanger E200 can be coiled tube heat exchangers, printed circuit board heat exchangers, or plate-fin heat exchangers; the heat exchange channels 201-205 of the second main heat exchanger E200 can be filled with a secondary hydrogen conversion agent.

[0032] In this embodiment, the packing materials for the primary secondary hydrogen converter RA100-1, the primary secondary hydrogen converter RA100-2, the secondary secondary hydrogen converter RA200, the tertiary secondary hydrogen converter RA300, the quaternary secondary hydrogen converter RA400, and the quinary secondary hydrogen converter RA500 can be iron-based catalysts or noble metal catalysts.

[0033] In this embodiment, the low-temperature adsorber A100, the primary secondary hydrogen converter RA100-1, the primary secondary hydrogen converter RA100-2, and the first main heat exchanger E100 are integrated in an 80K cold box; the secondary secondary hydrogen converter RA200, the tertiary secondary hydrogen converter RA300, the quaternary secondary hydrogen converter RA400, the quinary secondary hydrogen converter RA500, and the second main heat exchanger E200 are integrated in a 20K cold box; the "80K cold source" and the "25K cold source" can be gas, liquid, or a gas-liquid mixture.

[0034] A method for the conversion and activation of secondary hydrogen for hydrogen liquefaction, based on the aforementioned secondary hydrogen conversion device for hydrogen liquefaction, includes the following steps:

[0035] The process of converting hydrogen to tertiary hydrogen: The raw material hydrogen enters the raw material hydrogen pre-cooling channel 102 of the first main heat exchanger E100 through pipeline FH11 for heat exchange and cooling. Then, the gas enters the low-temperature adsorber A100 through pipeline FH12 to remove trace nitrogen, oxygen, and argon impurities. Then, the raw material hydrogen enters the primary primary hydrogen converter RA100-1 through pipeline FH13 for primary conversion of the raw material hydrogen to tertiary hydrogen. The heated gas enters the first raw material hydrogen cooling channel 103 of the first main heat exchanger E100 through pipeline FH14 for heat exchange and cooling. Then, the raw material hydrogen enters the primary secondary hydrogen converter RA100-2 through pipeline FH15 for primary secondary conversion of the raw material hydrogen to tertiary hydrogen. The heated gas flows back through pipeline FH16 into the second raw material hydrogen cooling channel 104 of the first main heat exchanger E100 for heat exchange and cooling. Finally, the raw material hydrogen enters the raw material hydrogen re-cooling channel 201 of the second main heat exchanger E200 through pipeline FH17 for further heat exchange and cooling.

[0036] The raw material hydrogen gas enters the secondary-stage antho- and para-hydrogen converter RA200 via pipeline FH21 for secondary antho- and para-hydrogen conversion. The heated gas then flows back through pipeline FH22 into the first hydrogen cooling channel 202 of the second main heat exchanger E200 for heat exchange and cooling. The cooled gas then flows through pipeline FH23 into the tertiary-stage antho- and para-hydrogen converter RA300 to complete the tertiary antho- and para-hydrogen conversion of the raw material hydrogen. The heated gas then flows back through pipeline FH24 into the second hydrogen cooling channel 203 of the second main heat exchanger E200 for heat exchange and cooling. The cooled gas then flows through pipeline... The gas flows through pipe FH25 and then enters the fourth-stage secondary hydrogen converter RA400 to complete the fourth-stage secondary hydrogen conversion of the feedstock hydrogen. The heated gas flows back through pipe FH26 into the third hydrogen cooling channel 204 of the second main heat exchanger E200 for heat exchange and cooling. The cooled gas flows through pipe FH27 and then enters the fifth-stage secondary hydrogen converter RA500 to complete the fifth-stage secondary hydrogen conversion of the feedstock hydrogen. The heated gas flows back through pipe FH28 into the fourth hydrogen cooling channel 205 of the second main heat exchanger E200 for heat exchange and cooling, finally yielding liquid hydrogen with a secondary hydrogen concentration ≥95%. The cooling capacity of the first main heat exchanger E100 is provided by an 80K cold source, and the cooling capacity of the second main heat exchanger E200 is provided by a 25K cold source.

[0037] Activation method of the n- and para-hydrogen catalyst: Activating nitrogen gas enters the nitrogen electric heater EH100 through the isolation valve VM19 and is heated to a certain temperature TI01. Then, it enters the catalyst bed of the primary n- and para-hydrogen converters RA100-1, RA100-2, RA200, RA300, RA400, and RA500. Activating nitrogen gas exits from the equipment outlet valve VM1. 5. Vent VM18 and VM23. After the outlet temperature and water dew point of the bed reach the predetermined values, shut off the activation nitrogen inlet valves VM12, VM17, VM19, and VM21, open valve VM25, and start the regeneration vacuum pump P100 for evacuation. After the vacuum degree PI02 meets the predetermined value, shut off the regeneration vacuum pump P100 and valve VM25. Follow the original activation steps to introduce dry replacement hydrogen through the isolation valve VM27 into each converter device for replacement. The replacement time is 6 to 24 hours.

[0038] In this embodiment, the primary secondary hydrogen converter RA100-1 and the secondary secondary hydrogen converter RA100-2 operate at pressures of 1.3–8 MPa and temperatures of -160–-196°C, respectively, and the secondary hydrogen concentration in the converted hydrogen is 35–50%.

[0039] In this embodiment, the working pressure of the two-stage secondary hydrogen converter RA200 to the five-stage secondary hydrogen converter RA500 is 1.3 to 8 MPa, and the working temperature is -200 to -248°C. The number of conversion stages in the temperature range of -210 to -248°C is ≥2, and the secondary hydrogen concentration in the converted hydrogen is not less than 95%.

[0040] In this embodiment, the activation nitrogen temperature is 80~165℃, the vacuum pump evacuation pressure is 1~133Pa.A, and the heating time is 8~24h.

[0041] In this embodiment, high-purity nitrogen is used as the activation gas and high-purity hydrogen is used as the replacement gas.

[0042] The activation process of this utility model adopts a segmented design. The ortho-parahydrogen conversion reactor in the 80K vacuum cold box is an isolated activation, which does not affect other equipment and has strong independence. The second to fifth stage ortho-parahydrogen conversion reactors in the 20K vacuum cold box are cascaded activations with fewer valves and strong operability. Nitrogen is used as the activation medium, which does not damage the catalyst. After activation, the vacuum pump is used for evacuation, resulting in a high activation depth and better safety.

[0043] Example 2

[0044] See Figure 2This utility model provides another embodiment. Compared with embodiment 1, the secondary-stage and tertiary-stage hydrogen converters RA200, RA300, and RA400 are eliminated in this embodiment. The feed hydrogen recooling channel 201, the first hydrogen cooling channel 202, the second hydrogen cooling channel 203, the third hydrogen cooling channel 204, and the fourth hydrogen cooling channel 205 of the second main heat exchanger E200 are filled with a hydrogen catalyst. The feed hydrogen undergoes hydrogen conversion while being cooled down.

[0045] It should be noted that the terms "connection" and "setting" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "connection" or "setting" may explicitly or implicitly include one or more of that feature. Furthermore, the terms "connection" and "setting," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the present invention described herein can be implemented in a sequence other than those illustrated or described herein. Moreover, for the foregoing embodiments, for the sake of simplicity, they are all described as a series of actions; however, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Secondly, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to this application.

[0046] 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 normal-para hydrogen conversion device for hydrogen liquefaction, characterized by comprising: The system includes a first main heat exchanger (E100), a second main heat exchanger (E200), a first secondary hydrogen conversion unit, and a second secondary hydrogen conversion unit. A first secondary hydrogen conversion unit is disposed between multiple input and output terminals of the first main heat exchanger (E100). The output terminal of the first secondary hydrogen conversion unit is connected to an output pipeline, and the input terminal of the first secondary hydrogen conversion unit is connected to an input pipeline. One output terminal of the first main heat exchanger (E100) is connected to the second main heat exchanger (E200). A second secondary hydrogen conversion unit is disposed between one or more input and output terminals of the second main heat exchanger (E200). The output terminal of the second secondary hydrogen conversion unit is connected to an output pipeline, which includes a liquid hydrogen pipeline and a venting pipeline. The input pipeline includes a nitrogen pipeline and a hydrogen pipeline.

2. The primary-sec ondary hydrogen conversion apparatus for hydrogen liquefaction according to claim 1, characterized by The first main heat exchanger (E100) is provided with a first cold source channel (101), a raw material hydrogen precooling channel (102), a first raw material hydrogen cooling channel (103), and a second raw material hydrogen cooling channel (104). The input end of the raw material hydrogen precooling channel (102) is connected to the raw material hydrogen pipeline (FH11). The output end of the raw material hydrogen precooling channel (102) and the first raw material hydrogen cooling channel (103) are connected to the first positive and negative hydrogen conversion unit. The output end of the first positive and negative hydrogen conversion unit is connected to the input ends of the first raw material hydrogen cooling channel (103) and the second raw material hydrogen cooling channel (104), respectively.

3. The ortho-para hydrogen conversion device for hydrogen liquefaction according to claim 2, wherein The first secondary hydrogen conversion unit includes a low-temperature adsorber (A100), a primary secondary hydrogen converter (RA100-1), and a secondary secondary hydrogen converter (RA100-2). The output of the feed hydrogen precooling channel (102) is connected to the input of the low-temperature adsorber (A100), and the output of the low-temperature adsorber (A100) is connected to the inputs of both the primary secondary secondary hydrogen converter (RA100-1) and the secondary secondary secondary hydrogen converter (RA100-2). The output end of the primary secondary hydrogen converter (RA100-1) is connected to the input end of the first raw material hydrogen cooling channel (103) and the input end of the second raw material hydrogen cooling channel (104), and is also connected to the output pipeline; the output end of the secondary secondary hydrogen converter (RA100-2) is connected to the input end of the second raw material hydrogen cooling channel (104) and the output end of the primary secondary hydrogen converter (RA100-1), and is also connected to the output pipeline.

4. The primary-sec ondary hydrogen conversion apparatus for hydrogen liquefaction according to claim 1, characterized by The second main heat exchanger (E200) is equipped with a raw material hydrogen recooling channel (201), a first hydrogen cooling channel (202), a second hydrogen cooling channel (203), a third hydrogen cooling channel (204), a fourth hydrogen cooling channel (205), and a second cold source channel (206). The input end of the raw material hydrogen recooling channel (201) is connected to the output end of the first main heat exchanger (E100) and the activated nitrogen and hydrogen pipelines, respectively. The raw material hydrogen recooling channel (201), the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), the third hydrogen cooling channel (204), the fourth hydrogen cooling channel (205), and the second cold source channel (206) are all connected to the first main heat exchanger (E100) and the activated nitrogen and hydrogen pipelines, respectively. The output ends of the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), and the third hydrogen cooling channel (204) are all connected to the input end of the second intermediate hydrogen conversion unit. The output end of the second intermediate hydrogen conversion unit is connected to the input ends of the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), the third hydrogen cooling channel (204), and the fourth hydrogen cooling channel (205), respectively. The output end of the fourth hydrogen cooling channel (205) is connected to the output pipeline.

5. The ortho-para hydrogen conversion device for hydrogen liquefaction according to claim 4, wherein The second secondary hydrogen conversion unit includes a secondary secondary hydrogen converter (RA200), a tertiary secondary hydrogen converter (RA300), a quaternary secondary hydrogen converter (RA400), and a quinary secondary hydrogen converter (RA500). The secondary secondary secondary hydrogen converter (RA200), tertiary secondary hydrogen converter (RA300), quaternary secondary hydrogen converter (RA400), and quinary secondary secondary hydrogen converter (RA500) are sequentially arranged between the feed hydrogen recooling channel (201), the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), the third hydrogen cooling channel (204), and the fourth hydrogen cooling channel (205).

6. The primary-sec ondary hydrogen conversion apparatus for hydrogen liquefaction according to claim 1, characterized by The second main heat exchanger (E200) is provided with a raw material hydrogen recooling channel (201), a first hydrogen cooling channel (202), a second hydrogen cooling channel (203), a third hydrogen cooling channel (204), a fourth hydrogen cooling channel (205), and a second cold source channel (206). The input end of the raw material hydrogen recooling channel (201) is connected to the output end of the first main heat exchanger (E100) and the activated nitrogen and hydrogen pipelines, respectively. The raw material hydrogen recooling channel (201), the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), and the third hydrogen cooling channel (204) are connected in sequence. A second positive and negative hydrogen conversion unit is provided between the third hydrogen cooling channel (204) and the fourth hydrogen cooling channel (205).

7. The ortho-para hydrogen conversion device for hydrogen liquefaction according to claim 6, wherein The second secondary hydrogen conversion unit includes a five-stage secondary hydrogen converter (RA500). The input end of the five-stage secondary hydrogen converter (RA500) is connected to the output end of the third hydrogen cooling channel (204), and the output end is connected to the input end of the fourth hydrogen cooling channel (205). Secondary hydrogen catalysts are provided in the feed hydrogen recooling channel (201), the first hydrogen cooling channel (202), the second hydrogen cooling channel (203), the third hydrogen cooling channel (204), and the fourth hydrogen cooling channel (205).

8. The primary-sec ondary hydrogen conversion apparatus for hydrogen liquefaction according to claim 1, characterized by One or more isolation valves are installed on the pipeline between the first main heat exchanger (E100), the second main heat exchanger (E200), the first secondary hydrogen conversion unit, and the second secondary hydrogen conversion unit.

9. The ortho-para hydrogen conversion apparatus for hydrogen liquefaction according to claim 4 or 6, wherein A regeneration vacuum pump (P100) is installed on the venting pipeline; a nitrogen electric heater (EH100) is installed on the activated nitrogen pipeline.

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