Hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration and use method

Abstract

The present invention provides a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration and a method of use. The hydrogen liquefaction system comprises a hydrogen liquefaction unit and a circulating hydrogen refrigerant refrigeration circulation circuit unit. The hydrogen liquefaction unit comprises a raw hydrogen boosting module, a liquefied cold box module, and a liquefied hydrogen storage module which are connected in sequence, and are used for comprehensive treatment and storage of the raw hydrogen liquefaction; the circulating hydrogen refrigerant refrigeration circulation circuit unit comprises a circulating hydrogen refrigerant compression module and the liquefied cold box module, and is used for cooling and liquefying the raw hydrogen. The present invention adopts a hydrogen liquefaction process of double-loop circulating hydrogen refrigeration, and provides corresponding cooling capacity according to different temperature ranges. The flow distribution of the refrigerant is optimized to meet the design requirements at the minimum total flow, and has good performance, low energy consumption, high liquefaction rate, high purity of product liquid hydrogen, small evaporation loss of liquid hydrogen, and high safety.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical engineering and cryogenic engineering, and in particular to a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration and a use method thereof. Background Art

[0002] As a high-quality clean energy, hydrogen has attracted more and more attention worldwide and is expected to become a major energy carrier. The use of hydrogen requires solving the problems of hydrogen production, storage, transportation and application, among which the long-distance storage of hydrogen energy is the key.

[0003] Highly compressed hydrogen, metal hydrides, ammonia, methylcyclohexane, liquid hydrogen, etc. can all be used to store hydrogen energy, but currently only liquid hydrogen can meet the requirements of mass, volume hydrogen storage density and hydrogen storage temperature. Therefore, liquefied hydrogen is an economical and efficient method to achieve long-distance storage and transportation of large amounts of hydrogen. It can provide low-pressure, high-energy density fuel for various applications and will play an important role in the clean energy industry chain.

[0004] Hydrogen liquefaction cycles are mainly divided into two categories: Linde-Hampson liquefaction cycle and Claude liquefaction cycle. The main difference between these two cycles lies in the expansion process: the first expansion process uses an expansion valve, and the second adds an expander. On the other hand, the basic cycles of hydrogen liquefaction also include simple Claude, Kapitsa, dual-pressure Claude, pre-cooled Linde-Hampson, pre-cooled dual-pressure Linde-Hampson, pre-cooled simple Claude, pre-cooled dual-pressure Claude, helium pre-cooled Claude and pre-cooled mixed refrigerant cycles. In the hydrogen liquefaction process, the refrigerants commonly used in the pre-cooling and refrigeration parts are hydrogen, helium, nitrogen and mixed refrigerants of different compositions. The advantages of using a hydrogen refrigeration cycle include the absence of additional refrigerants and phase change refrigeration and higher efficiency, but there is currently little research on the hydrogen refrigeration liquefaction process. Therefore, it is necessary to conduct a more in-depth study of the hydrogen refrigeration cycle.

[0005] Patent document CN108759301B discloses a hydrogen liquefaction process for recovering low-temperature gaseous hydrogen for use in a liquefaction process in combination with normal-parahydrogen conversion. The process uses hydrogen as a refrigerant to cool liquefied hydrogen, and recycles the low-temperature gaseous hydrogen vaporized in the liquid hydrogen storage tank, thereby avoiding energy waste from direct emissions and providing cooling capacity for hydrogen liquefaction and reducing energy consumption. However, the design does not take into account the differences in the components of the refrigerant and the vaporized hydrogen when recycling hydrogen. Summary of the invention

[0006] In view of the defects in the prior art, the object of the present invention is to provide a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration and a method of use.

[0007] According to the present invention, a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration is provided, comprising:

[0008] The hydrogen liquefaction unit includes a raw hydrogen booster module, a liquefied cold box module, and a liquefied hydrogen storage module which are connected in sequence, and is used for comprehensive processing and storage of the raw hydrogen liquefaction;

[0009] The circulating hydrogen refrigerant refrigeration cycle unit comprises a circulating hydrogen refrigerant compression module and the liquefaction cold box module, and is used to cool and liquefy the raw hydrogen.

[0010] Preferably, the raw hydrogen boosting module comprises a raw hydrogen first-stage compressor, a raw hydrogen first-stage cooler, a raw hydrogen second-stage compressor, and a raw hydrogen second-stage cooler which are connected in sequence.

[0011] Preferably, the liquefied cold box module includes a first-stage heat exchanger, a second-stage heat exchanger, a first-stage normal-parahydrogen converter, a third-stage heat exchanger, a circulating hydrogen distributor, a fourth-stage heat exchanger, a fifth-stage heat exchanger, a sixth-stage heat exchanger, a first-stage hydrogen throttling device, a seventh-stage heat exchanger, a second-stage normal-parahydrogen converter, a second-stage hydrogen throttling device, a first-stage refrigerant throttling device, a second-stage refrigerant throttling device, a refrigerant mixer, and a third-stage refrigerant throttling device;

[0012] The hydrogen output from the raw hydrogen boosting module passes through a first-stage heat exchanger, a second-stage heat exchanger, a first-stage normal-para-hydrogen converter, and then passes through a second-stage heat exchanger, a third-stage heat exchanger, a fourth-stage heat exchanger, a fifth-stage heat exchanger, a sixth-stage heat exchanger, a first-stage hydrogen throttling device, a seventh-stage heat exchanger, a second-stage normal-para-hydrogen converter, and then passes through a seventh-stage heat exchanger and a second-stage hydrogen throttling device before being transported to a liquefied hydrogen storage module for storage.

[0013] The hydrogen refrigerant output from the circulating hydrogen refrigerant compression module enters the circulating hydrogen distributor after passing through the first stage heat exchanger, the second stage heat exchanger, and the third stage heat exchanger, wherein the circulating hydrogen distributor includes a first outlet branch and a second outlet branch, wherein:

[0014] The first outlet branch is sequentially connected to the fourth-stage heat exchanger, the fifth-stage heat exchanger, the sixth-stage heat exchanger, the third-stage refrigerant throttling device, the seventh-stage heat exchanger, and then connected to the first mixer inlet branch of the refrigerant mixer after passing through the sixth-stage heat exchanger, the fifth-stage heat exchanger, the fourth-stage heat exchanger, the third-stage heat exchanger, the second-stage heat exchanger, and the first-stage heat exchanger;

[0015] The second outlet branch is sequentially connected to the first-stage refrigerant throttling device, the fifth-stage heat exchanger, the second-stage refrigerant throttling device, the sixth-stage heat exchanger, the fifth-stage heat exchanger, the fourth-stage heat exchanger, the third-stage heat exchanger, the second-stage heat exchanger, the first-stage heat exchanger, and then connected to the second mixer inlet branch of the refrigerant mixer;

[0016] The outlet of the refrigerant mixer is connected to the circulating hydrogen refrigerant compression module.

[0017] Preferably, the circulating hydrogen refrigerant compression module comprises a first-stage circulating hydrogen compressor, a first-stage circulating hydrogen cooler, a second-stage circulating hydrogen compressor, and a second-stage circulating hydrogen cooler which are connected in sequence.

[0018] Preferably, the first-stage heat exchanger, the second-stage heat exchanger, the third-stage heat exchanger, the fourth-stage heat exchanger, the fifth-stage heat exchanger, the sixth-stage heat exchanger, and the seventh-stage heat exchanger are all multi-stream heat exchangers, and the heat exchangers are in the form of plate-fin heat exchangers or coil-wound heat exchangers.

[0019] Preferably, the first-stage hydrogen throttling device, the second-stage hydrogen throttling device, the first-stage refrigerant throttling device, the second-stage refrigerant throttling device and the third-stage refrigerant throttling device respectively adopt any one of a throttling valve and an expander.

[0020] According to the present invention, a method for using a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration comprises the following steps:

[0021] S1: The raw hydrogen is pressurized and cooled by the raw hydrogen booster module, and then enters the first-stage heat exchanger, the second-stage heat exchanger for further cooling, and then enters the first-stage normal-parahydrogen converter for normal-parahydrogen conversion, and then enters the second-stage heat exchanger, the third-stage heat exchanger, the fourth-stage heat exchanger, the fifth-stage heat exchanger, and the sixth-stage heat exchanger for cooling step by step. After throttling and reducing the pressure by the first-stage hydrogen throttling device, it enters the seventh-stage heat exchanger for further cooling. After entering the second-stage normal-parahydrogen converter, it is converted into the normal-parahydrogen again, and then cooled by the seventh-stage heat exchanger, it enters the second-stage hydrogen throttling device for throttling and reducing the pressure to the liquefied hydrogen storage pressure. The liquid hydrogen coming out of the second-stage throttling device after reducing the pressure enters the liquefied hydrogen storage module;

[0022] S2: The circulating hydrogen refrigerant is pressurized and cooled by the circulating hydrogen refrigerant compression module, and then enters the first stage heat exchanger, the second stage heat exchanger, and the third stage heat exchanger for heat exchange and temperature reduction. After passing through the circulating hydrogen distributor, it is divided into two streams. Among them, one stream passes through the first stage refrigerant throttling device to reduce pressure and temperature, enters the fifth stage heat exchanger for heat exchange, and then enters the second stage refrigerant throttling device to reduce pressure and temperature, and then enters the sixth stage heat exchanger, the fifth stage heat exchanger, the fourth stage heat exchanger, the third stage heat exchanger, the second stage heat exchanger, the first stage heat exchanger, the The first heat exchanger provides cooling capacity; the other fluid passes through the fourth heat exchanger, the fifth heat exchanger, and the sixth heat exchanger for heat exchange and cooling, then enters the third refrigerant throttling device for throttling and cooling, then passes through the seventh heat exchanger for heat exchange, and then passes through the sixth heat exchanger, the fifth heat exchanger, the fourth heat exchanger, the third heat exchanger, the second heat exchanger, and the first heat exchanger in sequence to provide cooling capacity. After passing through the first heat exchanger, the two fluids are mixed in the refrigerant mixer and then return to the circulating hydrogen refrigerant compression module to complete the refrigeration cycle.

[0023] Preferably, when the raw hydrogen pressure is higher than 2.0 MPa, the raw hydrogen boosting module is not enabled.

[0024] Preferably, the storage pressure of the liquefied hydrogen storage module is not less than 0.15 MPa.

[0025] Preferably, the pre-cooling capacity of the first-stage heat exchanger and the second-stage heat exchanger both adopts liquid nitrogen.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention adopts a hydrogen liquefaction process of double-loop circulating hydrogen refrigeration to provide corresponding cooling capacity according to different temperature ranges. The flow distribution of the refrigerant is optimized to meet the design requirements at the minimum total flow, with good performance and low energy consumption.

[0028] 2. The liquefaction process of the present invention has low energy consumption, strong adaptability to different gas sources, is suitable for the liquefaction process of the hydrogen liquefaction device, and has strong practicality.

[0029] 3. The present invention has a high liquefaction rate, high purity of the product liquid hydrogen, small evaporation loss of liquid hydrogen and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0031] Figure 1 The process flow chart of the hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration of the present invention.

[0032] The figure shows:

[0033] 1-First stage compressor of raw hydrogen 15-Second stage normal-para hydrogen converter

[0034] 2-First stage cooler for raw hydrogen 16-Second stage hydrogen throttling device

[0035] 3- Second stage compressor of raw hydrogen 17- First stage refrigerant throttling device

[0036] 4- Second stage cooler for raw hydrogen 18- Second stage refrigerant throttling device

[0037] 5-First stage heat exchanger 19-Refrigerant mixer

[0038] 6- Second stage heat exchanger 20- First stage circulating hydrogen compressor

[0039] 7-First stage normal-parahydrogen converter 21-First stage circulating hydrogen cooler

[0040] 8- Third stage heat exchanger 22- Second stage circulating hydrogen compressor

[0041] 9- Circulating hydrogen distributor 23- Second stage circulating hydrogen cooler

[0042] 10-Fourth stage heat exchanger 24-Third stage refrigerant throttling device

[0043] 11-Fifth stage heat exchanger 25-Liquefied hydrogen storage module

[0044] 12-sixth stage heat exchanger 26-raw hydrogen booster module

[0045] 13-First stage hydrogen throttling device 27-Liquid cold box module

[0046] 14-7th stage heat exchanger 28-circulating hydrogen refrigerant compression module DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] The present invention provides a hydrogen liquefaction system based on dual-loop circulating hydrogen refrigeration, including a hydrogen liquefaction unit and a circulating hydrogen refrigerant refrigeration circulation circuit unit. The hydrogen liquefaction unit includes a raw hydrogen boosting module 26, a liquefied cold box module 27, and a liquefied hydrogen storage module 25 connected in sequence, which are used for comprehensive processing and storage of raw hydrogen liquefaction, specifically, for storing the raw hydrogen after dehydration, purification, compression, cooling and liquefaction, normal-parahydrogen conversion and pressure reduction; the circulating hydrogen refrigerant refrigeration circulation circuit unit includes a circulating hydrogen refrigerant compression module 28 and a liquefied cold box module 27, which are used for reasonably distributing and recycling hydrogen refrigerant to cool and liquefy the raw hydrogen.

[0049] Specifically, Figure 1 As shown, the raw hydrogen boosting module 26 includes a raw hydrogen first-stage compressor 1, a raw hydrogen first-stage cooler 2, a raw hydrogen second-stage compressor 3, and a raw hydrogen second-stage cooler 4 which are connected in sequence.

[0050] Furthermore, the liquefied cold box module 27 includes a first-stage heat exchanger 5, a second-stage heat exchanger 6, a first-stage normal-parahydrogen converter 7, a third-stage heat exchanger 8, a circulating hydrogen distributor 9, a fourth-stage heat exchanger 10, a fifth-stage heat exchanger 11, a sixth-stage heat exchanger 12, a first-stage hydrogen throttling device 13, a seventh-stage heat exchanger 14, a second-stage normal-parahydrogen converter 15, a second-stage hydrogen throttling device 16, a first-stage refrigerant throttling device 17, a second-stage refrigerant throttling device 18, a refrigerant mixer 19 and a third-stage refrigerant throttling device 24.

[0051] The hydrogen output from the raw hydrogen booster module 26 passes through the first-stage heat exchanger 5, the second-stage heat exchanger 6, the first-stage normal-para-hydrogen converter 7, and then passes through the second-stage heat exchanger 6, the third-stage heat exchanger 8, the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, the sixth-stage heat exchanger 12, the first-stage hydrogen throttling device 13, the seventh-stage heat exchanger 14, the second-stage normal-para-hydrogen converter 15, and then passes through the seventh-stage heat exchanger 14 and the second-stage hydrogen throttling device 16 before being transported to the liquefied hydrogen storage module 25 for storage.

[0052] The hydrogen refrigerant output from the circulating hydrogen refrigerant compression module 28 enters the circulating hydrogen distributor 9 after passing through the first stage heat exchanger 5, the second stage heat exchanger 6, and the third stage heat exchanger 8, wherein the circulating hydrogen distributor 9 includes a first outlet branch 91 and a second outlet branch 92, wherein:

[0053] The first outlet branch 91 is connected to the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, the sixth-stage heat exchanger 12, the third-stage refrigerant throttling device 24, and the seventh-stage heat exchanger 14 in sequence, and then passes through the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, and the first-stage heat exchanger 5, and is connected to the first mixer inlet branch 191 of the refrigerant mixer 19.

[0054] The second outlet branch 92 is connected in sequence to the first-stage refrigerant throttling device 17, the fifth-stage heat exchanger 11, the second-stage refrigerant throttling device 18, the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, and the first-stage heat exchanger 5, and then connected to the second mixer inlet branch 192 of the refrigerant mixer 19. The outlet of the refrigerant mixer 19 is connected to the circulating hydrogen refrigerant compression module 28.

[0055] like Figure 1 As shown, the circulating hydrogen refrigerant compression module 28 includes a first-stage circulating hydrogen compressor 20, a first-stage circulating hydrogen cooler 21, a second-stage circulating hydrogen compressor 22, and a second-stage circulating hydrogen cooler 23 which are connected in sequence.

[0056] It should be noted that the first-stage heat exchanger 5, the second-stage heat exchanger 6, the third-stage heat exchanger 8, the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, the sixth-stage heat exchanger 12, and the seventh-stage heat exchanger 14 are all multi-stream heat exchangers, and the heat exchanger is in the form of a plate-fin heat exchanger or a coiled heat exchanger, which can fully achieve the effect of heat exchange and improve the heat exchange efficiency.

[0057] The first-stage hydrogen throttling device 13, the second-stage hydrogen throttling device 16, the first-stage refrigerant throttling device 17, the second-stage refrigerant throttling device 18, and the third-stage refrigerant throttling device 24 can adopt any one of throttling valves and expanders according to actual needs.

[0058] The present invention can also be configured according to actual needs of the system, such as a nitrogen liquefaction unit, an instrument control unit, an instrument wind meter, a PSA nitrogen production module, and a generator module. For example, the generator module is used to provide electrical energy for the reliquefaction process when there is no power supply system, thereby playing a role of backup power supply.

[0059] The present invention also provides a method for using a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration, such as Figure 1 As shown, the following steps are included:

[0060] S1: After the raw hydrogen is dehydrated and purified to remove moisture and impurities, it is pressurized and cooled by the raw hydrogen booster module 26 and then enters the first-stage heat exchanger 5 and the second-stage heat exchanger 6 in sequence for further cooling, and then enters the first-stage normal-para-hydrogen converter 7 for normal-para-hydrogen conversion, and then enters the second-stage heat exchanger 6, the third-stage heat exchanger 8, the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, and the sixth-stage heat exchanger 12 for step-by-step cooling, and then enters the seventh-stage heat exchanger 14 for further cooling after throttling and reducing the pressure in the first-stage hydrogen throttling device 13, and then enters the second-stage hydrogen throttling device 16 for throttling and reducing the pressure to the liquefied hydrogen storage pressure after entering the second-stage normal-para-hydrogen converter 15 for another normal-para-hydrogen conversion, and then enters the second-stage hydrogen throttling device 16 for throttling and reducing the pressure to the liquefied hydrogen storage pressure after cooling in the seventh-stage heat exchanger 14. The liquid hydrogen coming out of the second-stage throttling device 16 after reducing the pressure enters the liquefied hydrogen storage module 25;

[0061] S2: The circulating hydrogen refrigerant is pressurized and cooled by the circulating hydrogen refrigerant compression module 28, and then enters the first-stage heat exchanger 5, the second-stage heat exchanger 6, and the third-stage heat exchanger 8 for heat exchange and temperature reduction. After passing through the circulating hydrogen distributor 9, it is divided into two streams. Among them, one stream passes through the first-stage refrigerant throttling device 17 to reduce pressure and temperature, enters the fifth-stage heat exchanger 11 for heat exchange, and then enters the second-stage refrigerant throttling device 18 to reduce pressure and temperature, and then enters the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, the first-stage The heat exchanger 5 provides cooling capacity; the other fluid passes through the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, and the sixth-stage heat exchanger 12 for heat exchange and cooling, then enters the third-stage refrigerant throttling device 24 for throttling and cooling, then passes through the seventh-stage heat exchanger 14 for heat exchange, and then passes through the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, and the first-stage heat exchanger 5 in sequence to provide cooling capacity. After passing through the first-stage heat exchanger 5, the two fluids are mixed in the refrigerant mixer 19 and then return to the circulating hydrogen refrigerant compression module 28 to complete the refrigeration cycle.

[0062] It should be noted that when the raw hydrogen pressure is higher than 2.0 MPa, the raw hydrogen booster module 26 is not enabled, and the storage pressure of the liquefied hydrogen storage module 25 is preferably not less than 0.15 MPa. The pre-cooling capacity of the first stage heat exchanger 5 and the second stage heat exchanger 6 is preferably liquid nitrogen.

[0063] To more clearly describe the present invention, a specific embodiment is provided below to further illustrate the present invention.

[0064] The pressure of the raw hydrogen is 0.1MPa, the temperature is 25℃, the molar composition is 25.1% para-hydrogen, 74.9% ortho-hydrogen, the flow rate is 63kmol / h; the circulating hydrogen refrigerant flow rate is 278.6kmol / h. The hydrogen liquefaction system adopts liquid nitrogen precooling and double-circuit circulating hydrogen refrigeration. The specific steps of liquefying hydrogen are as follows:

[0065] M1: The raw hydrogen is purified and dehydrated to be free of moisture and impurities;

[0066] M2: The raw hydrogen obtained by the pretreatment of M1 is compressed to 2.4Mpa by a raw hydrogen two-stage compressor (raw hydrogen first-stage compressor 1, raw hydrogen second-stage compressor 3), and cooled to 37°C by a raw hydrogen two-stage cooler (raw hydrogen first-stage cooler 2, raw hydrogen second-stage cooler 4);

[0067] M3: The raw hydrogen from M2 is cooled to -192°C through the first-stage heat exchanger 5 and the second-stage heat exchanger 6, and then converted to the normal-parahydrogen state through the first-stage normal-parahydrogen converter 7 until the composition becomes 49.8% para-hydrogen and 50.2% ortho-hydrogen;

[0068] M4: The raw hydrogen converted by M3 is cooled to -236°C through the third-stage heat exchanger 8, the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, and the sixth-stage heat exchanger 12;

[0069] M5: The raw hydrogen cooled by M4 is throttled and depressurized to 1.4 MPa by the first-stage hydrogen throttling device 13, and then enters the seventh-stage heat exchanger 14 to be cooled to -245°C, and enters the second-stage normal-parahydrogen converter 15 to be converted to normal-parahydrogen again until the composition becomes 99.1% para-hydrogen and 0.9% ortho-hydrogen.

[0070] M6: The raw hydrogen converted by M5 is throttled and depressurized to 0.15 MPa by the second-stage hydrogen throttling device 16, and then enters the liquefied hydrogen storage module 25;

[0071] M7: The circulating hydrogen refrigerant is compressed to 2.87 MPa by a two-stage circulating hydrogen compressor (a first-stage circulating hydrogen compressor 20 and a second-stage circulating hydrogen compressor 22), and cooled to 37° C. by a two-stage circulating hydrogen cooler (a first-stage circulating hydrogen cooler 21 and a second-stage circulating hydrogen cooler 23);

[0072] M8: The circulating hydrogen refrigerant from M7 is cooled to -204°C through the first stage heat exchanger 5, the second stage heat exchanger 6 and the third stage heat exchanger 8;

[0073] M9: The circulating hydrogen cooled by M8 enters the circulating hydrogen distributor 9 and is divided into two streams. One stream is depressurized to 0.69 MPa by the first-stage refrigerant throttling device 17 and then enters the fifth-stage heat exchanger 11 for heat exchange, and enters the second-stage refrigerant throttling device 18 to be depressurized to 0.14 MPa. The depressurized fluid enters the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, and the first-stage heat exchanger 5 to be heated to -195°C;

[0074] M10: Another fluid distributed by the M9 circulating hydrogen distributor is cooled to -236°C by the fourth-stage heat exchanger 10, the fifth-stage heat exchanger 11, and the sixth-stage heat exchanger 12, and enters the third-stage refrigerant throttling device 24 to be throttled to 0.14MPa. The depressurized fluid is heated to -196°C by the seventh-stage heat exchanger 14, the sixth-stage heat exchanger 12, the fifth-stage heat exchanger 11, the fourth-stage heat exchanger 10, the third-stage heat exchanger 8, the second-stage heat exchanger 6, and the first-stage heat exchanger 5;

[0075] M11: The two circulating hydrogen gases heated by M9 and M10 enter the refrigerant mixer 19 for mixing and then return to the first-stage circulating hydrogen compressor 20 to complete the refrigeration cycle.

[0076] The unit energy consumption of the hydrogen liquefaction system based on double-loop hydrogen refrigeration is 8.978 kWh / Nm through simulation calculation using HYSYS software widely used in the oil and gas industry. 3 After passing through two-stage normal-parahydrogen converters (first-stage normal-parahydrogen converter 7 and second-stage normal-parahydrogen converter 15), the parahydrogen content in the raw hydrogen is 99.1%, and the liquefaction rate reaches 100%.

[0077] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0078] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0079] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration, It is characterized in that include: The hydrogen liquefaction unit comprises a raw hydrogen pressurizing module (26), a liquefied cold box module (27), and a liquefied hydrogen storage module (25) which are connected in sequence, and is used for comprehensive processing and storage of liquefied raw hydrogen; A circulating hydrogen refrigerant refrigeration cycle unit, comprising a circulating hydrogen refrigerant compression module (28) and the liquefaction cold box module (27), for cooling and liquefying the raw hydrogen; The liquefied cold box module (27) comprises a first-stage heat exchanger (5), a second-stage heat exchanger (6), a first-stage normal-parahydrogen converter (7), a third-stage heat exchanger (8), a circulating hydrogen distributor (9), a fourth-stage heat exchanger (10), a fifth-stage heat exchanger (11), a sixth-stage heat exchanger (12), a first-stage hydrogen throttling device (13), a seventh-stage heat exchanger (14), a second-stage normal-parahydrogen converter (15), a second-stage hydrogen throttling device (16), a first-stage refrigerant throttling device (17), a second-stage refrigerant throttling device (18), a refrigerant mixer (19) and a third-stage refrigerant throttling device (24); The hydrogen output from the raw hydrogen boosting module (26) passes through a first-stage heat exchanger (5), a second-stage heat exchanger (6), a first-stage normal-para hydrogen converter (7), and then passes through a second-stage heat exchanger (6), a third-stage heat exchanger (8), a fourth-stage heat exchanger (10), a fifth-stage heat exchanger (11), a sixth-stage heat exchanger (12), a first-stage hydrogen throttling device (13), a seventh-stage heat exchanger (14), a second-stage normal-para hydrogen converter (15), and then passes through a seventh-stage heat exchanger (14) and a second-stage hydrogen throttling device (16) before being transported to a liquefied hydrogen storage module (25) for storage; The hydrogen refrigerant output from the circulating hydrogen refrigerant compression module (28) passes through a first-stage heat exchanger (5), a second-stage heat exchanger (6), and a third-stage heat exchanger (8) and then enters a circulating hydrogen distributor (9), wherein the circulating hydrogen distributor (9) comprises a first outlet branch (91) and a second outlet branch (92), wherein: The first outlet branch (91) is connected in sequence to the fourth-stage heat exchanger (10), the fifth-stage heat exchanger (11), the sixth-stage heat exchanger (12), the third-stage refrigerant throttling device (24), and the seventh-stage heat exchanger (14), and then passes through the sixth-stage heat exchanger (12), the fifth-stage heat exchanger (11), the fourth-stage heat exchanger (10), the third-stage heat exchanger (8), the second-stage heat exchanger (6), and the first-stage heat exchanger (5), and is then connected to the first mixer inlet branch (191) of the refrigerant mixer (19); The second outlet branch (92) is sequentially connected to the first-stage refrigerant throttling device (17), the fifth-stage heat exchanger (11), the second-stage refrigerant throttling device (18), the sixth-stage heat exchanger (12), the fifth-stage heat exchanger (11), the fourth-stage heat exchanger (10), the third-stage heat exchanger (8), the second-stage heat exchanger (6), and the first-stage heat exchanger (5), and then connected to the second mixer inlet branch (192) of the refrigerant mixer (19); The outlet of the refrigerant mixer (19) is connected to the circulating hydrogen refrigerant compression module (28).

2. The hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration according to claim 1, It is characterized in that The raw hydrogen boosting module (26) comprises a raw hydrogen first-stage compressor (1), a raw hydrogen first-stage cooler (2), a raw hydrogen second-stage compressor (3), and a raw hydrogen second-stage cooler (4) which are connected in sequence.

3. The hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 1, It is characterized in that The circulating hydrogen refrigerant compression module (28) comprises a first-stage circulating hydrogen compressor (20), a first-stage circulating hydrogen cooler (21), a second-stage circulating hydrogen compressor (22), and a second-stage circulating hydrogen cooler (23) which are connected in sequence.

4. The hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 1, It is characterized in that The first-stage heat exchanger (5), the second-stage heat exchanger (6), the third-stage heat exchanger (8), the fourth-stage heat exchanger (10), the fifth-stage heat exchanger (11), the sixth-stage heat exchanger (12), and the seventh-stage heat exchanger (14) are all multi-stream heat exchangers, and the heat exchangers are in the form of plate-fin heat exchangers or coil-wound heat exchangers.

5. The hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 1, It is characterized in that The first-stage hydrogen throttling device (13), the second-stage hydrogen throttling device (16), the first-stage refrigerant throttling device (17), the second-stage refrigerant throttling device (18), and the third-stage refrigerant throttling device (24) respectively adopt any one of a throttling valve and an expansion machine.

6. A method for using a hydrogen liquefaction system based on double-loop circulating hydrogen refrigeration, It is characterized in that The steps include: S1: The raw hydrogen is pressurized and cooled by the raw hydrogen pressurizing module (26), and then enters the first stage heat exchanger (5), the second stage heat exchanger (6) in sequence, and then enters the first stage normal-parahydrogen converter (7) for normal-parahydrogen conversion, and then enters the second stage heat exchanger (6), the third stage heat exchanger (8), the fourth stage heat exchanger (10), the fifth stage heat exchanger (11), and the sixth stage heat exchanger (12) in sequence for cooling step by step, and then enters the seventh stage heat exchanger (14) for further cooling after throttling and reducing the pressure in the first stage hydrogen throttling device (13), and then enters the second stage hydrogen throttling device (16) for throttling and reducing the pressure to the liquefied hydrogen storage pressure after entering the second stage normal-parahydrogen converter (15) for normal-parahydrogen conversion again, and then enters the second stage hydrogen throttling device (16) for throttling and reducing the pressure to the liquefied hydrogen storage pressure after cooling. The liquefied hydrogen discharged from the second stage throttling device (16) after reducing the pressure enters the liquefied hydrogen storage module (25); S2: After being pressurized and cooled by the circulating hydrogen refrigerant compression module (28), the circulating hydrogen refrigerant enters the first-stage heat exchanger (5), the second-stage heat exchanger (6), and the third-stage heat exchanger (8) for heat exchange and temperature reduction, and then passes through the circulating hydrogen distributor (9) and is divided into two streams, wherein one stream passes through the first-stage refrigerant throttling device (17) for pressure reduction and temperature reduction, and then enters the fifth-stage heat exchanger (11) for heat exchange, and then enters the second-stage refrigerant throttling device (18) for pressure reduction and temperature reduction, and then enters the sixth-stage heat exchanger (12), the fifth-stage heat exchanger (11), the fourth-stage heat exchanger (10), the third-stage heat exchanger (8), the second-stage heat exchanger (6), the first-stage heat exchanger ( 5) to provide cooling capacity; the other fluid passes through the fourth-stage heat exchanger (10), the fifth-stage heat exchanger (11), and the sixth-stage heat exchanger (12) for heat exchange and cooling, then enters the third-stage refrigerant throttling device (24) for throttling and cooling, then passes through the seventh-stage heat exchanger (14) for heat exchange, and then passes through the sixth-stage heat exchanger (12), the fifth-stage heat exchanger (11), the fourth-stage heat exchanger (10), the third-stage heat exchanger (8), the second-stage heat exchanger (6), and the first-stage heat exchanger (5) in sequence to provide cooling capacity; the two fluids pass through the first-stage heat exchanger (5), are mixed in the refrigerant mixer (19), and then return to the circulating hydrogen refrigerant compression module (28) to complete the refrigeration cycle.

7. The method for using the hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 6, It is characterized in that When the raw hydrogen pressure is higher than 2.0 MPa, the raw hydrogen boosting module (26) is not enabled.

8. The method for using the hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 6, It is characterized in that The storage pressure of the liquefied hydrogen storage module (25) is not less than 0.15 MPa.

9. The method for using the hydrogen liquefaction system based on double-circuit circulating hydrogen refrigeration according to claim 6, It is characterized in that Liquid nitrogen is used as the pre-cooling capacity of the first-stage heat exchanger (5) and the second-stage heat exchanger (6).

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