Two-stage precooling hydrogen liquefying device

Abstract

The utility model discloses a two-stage precooling hydrogen liquefying device which comprises a precooling section and a liquefying section, and the precooling section comprises a first precooling system and a second precooling system. The liquefaction section mainly comprises heat exchangers of all stages and an ortho-parahydrogen converter, the liquefied hydrogen channel is sequentially communicated with the heat exchangers of all stages, and finally generated liquid hydrogen is stored in a liquid hydrogen storage tank. Helium compression is low-temperature compression, so that the compression work is obviously reduced, and the thermodynamic efficiency of the system is improved; hydrogen is liquefied through cold energy provided by a low-temperature helium circulating system and a first precooling system and a second precooling system, a hydrogen compression process is avoided, and the safety of a hydrogen liquefaction process is obviously improved; the centrifugal compressor adopting the gas bearing or the magnetic-gas hybrid bearing has the advantages of small size, high efficiency, no need of lubricating oil, no maintenance and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrogen liquefaction, in particular to a two-stage precooling hydrogen liquefaction device. Background Art

[0002] The use of hydrogen energy can solve the problems of sustainability, pollution emissions and energy security. Under the dual carbon goals, the global hydrogen energy industry is expected to grow rapidly and has huge room for development. In addition, the density of liquid hydrogen is much higher than that of gaseous hydrogen. Under the same volume, liquid hydrogen can provide higher energy density. Therefore, efficient and energy-saving hydrogen liquefaction processes will play a vital role in meeting the growing demand for hydrogen energy.

[0003] In the traditional helium refrigeration hydrogen liquefaction process, screw compressors are mostly used. Screw compressors have low speed, large mechanical wear, high noise, relatively low efficiency, and require the use of lubricating oil, with oil removal components, and complex system maintenance. In addition, in the current helium liquefaction system, the compressor compression process is compressed at room temperature (300K). Helium is difficult to be compressed at room temperature. The power consumption of the compressor at room temperature is greater than that at low temperature, and the efficiency is low.

[0004] At present, the helium refrigeration hydrogen liquefaction process generally adopts liquid nitrogen pre-cooling. Liquid nitrogen preparation usually utilizes gas separation technology, including compression, cooling, drying and separation. The preparation process is complicated and the liquefaction rate is low. If liquid nitrogen is not used, liquid nitrogen must be purchased separately. Liquid nitrogen is expensive. For industrial large-scale production of liquid hydrogen, the use of liquid nitrogen pre-cooling will reduce the economy of the circulation system. Summary of the invention

[0005] In view of this, it is necessary to provide a two-stage precooling hydrogen liquefaction device to address the problems existing in the prior art. The utility model has the advantages of simple equipment, relatively low cost and low energy consumption.

[0006] The purpose of the utility model is achieved through the following technical solutions.

[0007] The new hydrogen liquefaction process includes: a precooling section and a liquefaction section. The precooling section includes: a first precooling system and a second precooling system. The first precooling system includes: a low-temperature compressor, a medium-temperature compressor, a high-temperature compressor, a first-stage evaporative condenser, a second-stage evaporative condenser, a third-stage condenser, a first-stage throttling device, a second-stage throttling device, and a third-stage throttling device. The high-temperature and high-pressure gas at the outlet of the low-temperature compressor enters the condensation side of the first-stage evaporative condenser to release heat, and becomes a high-temperature liquid after heat release. After expansion and throttling through the first-stage throttling device, the low-temperature and low-pressure liquid flows into the first-stage heat exchanger of the liquefaction section, absorbs the heat of the normal-temperature hydrogen in the first-stage heat exchanger of the liquefaction section, and becomes a low-temperature gas, so that the normal-temperature hydrogen is precooled initially, and the low-temperature gas continues to flow into the inlet of the low-temperature compressor to realize the low-temperature cycle. The medium-temperature cycle realized by the medium-temperature compressor and the evaporation side of the first-stage evaporative condenser, the condensation side of the second-stage evaporative condenser, and the second-stage throttling device is the same as the above-mentioned low-temperature heat exchange process. Similarly, the high-temperature cycle realized by the high-temperature compressor, the evaporation side of the secondary evaporative condenser, the third-stage condenser, and the third-stage throttling device is also consistent with the low-temperature cycle. The heat absorbed from the first-stage heat exchanger of the liquefaction section is released to the external environment by the third-stage condenser;

[0008] The second precooling system includes: a first-stage compressor, an aftercooler, a booster compressor, a regenerator, and an expander. The high-pressure gas at the outlet of the first-stage compressor enters the aftercooler to cool down, the cooled gas enters the booster compressor to increase the pressure, then enters the regenerator to exchange heat with the reflux gas, and then enters the expander for adiabatic expansion refrigeration. The low-temperature gas coming out of the expander is the hydrogen of the hydrogen liquefaction system for the second precooling. The precooled gas passes through the regenerator for heat exchange and finally enters the first-stage compressor, completing the entire second precooling system cycle;

[0009] The liquefaction section includes: a hydrogen liquefaction section and a helium refrigeration section. The hydrogen liquefaction section includes: a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a quaternary heat exchanger, a 5th heat exchanger, a primary para-hydrogen converter, a secondary para-hydrogen converter, and a tertiary para-hydrogen converter. Each stage of the heat exchanger and the para-hydrogen converter is provided with a liquefied hydrogen channel. The liquefied hydrogen channels of the primary heat exchanger, the secondary heat exchanger, the primary para-hydrogen converter, the tertiary heat exchanger, the secondary para-hydrogen converter, the 4th heat exchanger, the tertiary para-hydrogen converter, and the 5th heat exchanger are connected in sequence. The outlet of the liquefied hydrogen channel in the 5th heat exchanger is connected to the first storage tank, and then the liquid hydrogen is stored in the liquid hydrogen storage tank through the liquid hydrogen delivery pipe.

[0010] The helium refrigeration section includes: a gas-suspended centrifugal cryogenic compressor unit, a cooler, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a quaternary heat exchanger, a quintuple heat exchanger, a helium throttle valve, a primary helium throttle valve, a primary turbine expander, a secondary turbine expander, a high-pressure pipeline, and a low-pressure pipeline. The high-pressure pipeline of the helium refrigeration is connected with the heat exchangers at each level in sequence, and the low-pressure pipeline is connected with the heat exchangers at each level and the normal-parahydrogen converters at each level in sequence. Helium at low temperature and normal pressure enters the compressor unit, and flows to the high-pressure pipeline after being heated and pressurized. After being initially cooled down by the cooler, the helium with reduced temperature continues to enter the secondary heat exchanger. After passing through the secondary heat exchanger, the helium is split into two paths. One path flows through the helium throttle valve, the first-stage turbine expander, the third-stage heat exchanger, and the second-stage turbine expander. The low-temperature helium coming out of the second-stage turbine expander flows back to the low-pressure pipeline. The other path of helium passes through the third-stage heat exchanger, the fourth-stage heat exchanger, and the fifth-stage heat exchanger in turn, and then returns to the low-pressure pipeline through the first-stage helium throttle valve and enters the low-pressure inlet of the compressor unit to complete the entire cycle.

[0011] Preferably, the temperature of hydrogen at room temperature of 300K is reduced to 110~180K by the first precooling system, and the temperature is reduced to 60~130K by the second precooling system. The two-stage precooling greatly reduces the cooling time of hydrogen liquefaction and improves the system efficiency.

[0012] Preferably, the gas-suspended centrifugal cryogenic compressor unit is two two-stage compression type compressors connected in series to complete four-stage compression, and primary and secondary precooling are performed between the two compressors to keep the helium at the inlet of the second compressor in a low temperature state, and inter-stage precooling effectively reduces the power consumption of the compressor.

[0013] Preferably, the compressors in the entire hydrogen liquefaction process are all centrifugal compressors, supported by gas bearings or magnetic hybrid bearings, and have the advantages of small size, low noise, high efficiency, no need for lubricating oil, and maintenance-free.

[0014] Preferably, the working fluids that may be used in the second precooling system and the secondary precooling system are air, nitrogen, neon, argon, etc.

[0015] Preferably, the operating temperature of the low-pressure inlet of the helium refrigeration section compressor unit is in the temperature range of 20~160K.

[0016] Preferably, the helium refrigeration section includes five stages of heat exchangers, and each stage of heat exchangers is connected in sequence. The number of heat exchanger stages is not limited to five, and can be increased or decreased according to actual engineering cases.

[0017] Preferably, the hydrogen liquefaction includes three stages of the above-mentioned normal-para-hydrogen converter, and the number of normal-para-hydrogen converter stages is not limited to three, and can be increased or decreased according to actual engineering cases.

[0018] Furthermore, the catalyst in the normal-parahydrogen converter is one of iron oxide, iron hydroxide, chromium dioxide, hydrous iron oxide, silica gel-supported nickel and silica gel-supported chromium oxide.

[0019] Preferably, the low-temperature gas or low-temperature gas-liquid mixture at the outlet of the five-stage heat exchanger first enters the first storage tank through the liquid hydrogen flow channel for gas-liquid separation, the gas flows back to the heat exchanger for further heat exchange and cooling, and the liquid hydrogen is stored in the liquid hydrogen storage tank through the liquid hydrogen delivery pipe.

[0020] Preferably, in the helium refrigeration process, the helium coming out of the secondary heat exchanger is split into two paths, in which the high-pressure and low-temperature gas enters the helium throttle valve for throttling and pressure reduction, and the throttled and pressure-reduced gas enters the first-stage turbine expander for expansion and cooling, and then passes through the third-stage heat exchanger for further cooling, and the low-temperature gas enters the second-stage turbine expander for cooling and pressure reduction, and the low-temperature and low-pressure helium flows into the low-pressure inlet of the fourth-stage heat exchanger to form low-temperature and low-pressure return gas. The cold energy generated in the whole process is used to cool the low-temperature and high-pressure helium to produce liquid helium.

[0021] The advantages of the utility model are:

[0022] (1) The new hydrogen liquefaction process cools hydrogen at different temperature ranges through the first precooling system and the second precooling system, which greatly reduces the hydrogen liquefaction time and improves the system efficiency;

[0023] (2) The low-temperature compressor unit of the helium refrigeration section of the new hydrogen liquefaction process is composed of two two-stage compression compressors connected in series to complete four-stage compression. By reasonably controlling the compressor pressure ratio, the compressor shaft power can be effectively reduced, which can not only reduce equipment costs, but also reduce the energy consumption of hydrogen liquefaction;

[0024] (3) All compressors in the system are centrifugal compressors, supported by gas bearings or magnetic hybrid bearings, which have the advantages of small size, low noise, high efficiency, no need for lubricating oil, and maintenance-free;

[0025] (4) The operating temperature of the low-pressure inlet of the helium refrigeration section compressor unit is in the temperature range of 20K~160K. Compared with the normal temperature 300K working condition, the power consumption of the compressor is significantly reduced, and the energy consumption of the hydrogen liquefaction thermal system is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0027] Figure 1 The utility model is a system schematic diagram of a two-stage precooling hydrogen liquefaction device.

[0028] Figure 2This is a schematic diagram of a first precooling system of a two-stage precooling hydrogen liquefaction device of the utility model.

[0029] Figure 3 It is a schematic diagram of the second precooling system of a two-stage precooling hydrogen liquefaction device of the utility model.

[0030] Figure 4 It is a schematic diagram of a gas-suspended centrifugal cryogenic compressor unit of a two-stage precooling hydrogen liquefaction device of the utility model.

[0031] Figure 5 This is a schematic diagram of the first-stage precooling system of the gas-suspended centrifugal cryogenic compressor unit of the utility model (the precooling process of the first-stage precooling system is the same as that of the first precooling system, but the equipment numbers are different).

[0032] Figure 6 This is a schematic diagram of the secondary precooling system of the gas-suspended centrifugal cryogenic compressor unit of the utility model (the secondary precooling system has the same precooling process as the second precooling system, but the equipment numbers are different).

[0033] Figure 7 Schematic diagram of an air-suspended centrifugal normal temperature compressor unit. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0035] The novel hydrogen liquefaction device and method provided by the embodiment of the utility model include: precooling section 1, 3 and liquefaction section 2. The precooling section 1 is shown in FIG. Figure 2The precooling section 1 is the first precooling system, including: a first-stage evaporative condenser 101, a second-stage evaporative condenser 102, a third-stage condenser 103, a low-temperature compressor 104, a medium-temperature compressor 105, a high-temperature compressor 106, a first-stage throttling device 107, a second-stage throttling device 108, and a third-stage throttling device 109. The high-temperature and high-pressure gas at the outlet of the low-temperature compressor 104 enters the condensation side of the first-stage evaporative condenser 101 to release heat, and becomes a high-temperature liquid after heat release. After expansion and throttling through the first-stage throttling device 107, the low-temperature and low-pressure liquid flows into the first-stage heat exchanger 203 of the liquefaction section, absorbs the heat of the normal-temperature hydrogen in the first-stage heat exchanger 203 of the liquefaction section, and becomes a low-temperature gas, so that the normal-temperature hydrogen is preliminarily precooled, and the low-temperature gas continues to flow into the inlet of the low-temperature compressor 104 to realize the low-temperature cycle. The medium-temperature cycle implemented by the medium-temperature compressor 105, the evaporation side of the first-stage evaporative condenser 101, the condensation side of the second-stage evaporative condenser 102, and the second-stage throttling device 108 is the same as the above-mentioned low-temperature heat exchange process. Similarly, the high-temperature cycle implemented by the high-temperature compressor 106, the evaporation side of the second-stage evaporative condenser 102, the third-stage condenser 103, and the third-stage throttling device 109 is also consistent with the low-temperature cycle. The heat absorbed from the first-stage heat exchanger 103 of the liquefaction stage is released to the external environment by the third-stage condenser 103;

[0036] Precooling section 3, please refer to Figure 3 . The precooling section 3 is the second precooling system, including: a regenerator 301, a first-stage compressor 302, an aftercooler 303, a booster compressor 304, and an expander 305. The high-pressure gas at the outlet of the first-stage compressor 302 enters the aftercooler 303 to cool down, and the cooled gas enters the booster compressor 304 to increase the pressure, and then enters the regenerator 301 to exchange heat with the reflux gas, and then enters the expander 305 for adiabatic expansion refrigeration. The low-temperature gas coming out of the expander 305 is the hydrogen of the hydrogen liquefaction system for the second precooling. The precooled gas passes through the regenerator 301 for heat exchange and finally enters the first-stage compressor 302, completing the entire second precooling system cycle;

[0037] Liquefaction Section 2 Figure 1 It includes: a gas-suspended centrifugal cryogenic compressor unit 201, a cooler 202, a primary heat exchanger 203, a secondary heat exchanger 204, a tertiary heat exchanger 205, a quaternary heat exchanger 206, a quintuple heat exchanger 207, a primary turbine expander 208, a secondary turbine expander 209, a helium throttle valve 210, a primary helium throttle valve 211, a high-pressure pipeline 212, a low-pressure pipeline 213, a primary normal-para-hydrogen converter 214, a secondary normal-para-hydrogen converter 215, a tertiary normal-para-hydrogen converter 216, a first storage tank 217, a liquid hydrogen storage tank 218, and a liquefied hydrogen channel 219;

[0038] The liquefaction section 2 includes a hydrogen liquefaction section and a helium refrigeration section, wherein the hydrogen liquefaction section includes: a first-stage heat exchanger 203, a second-stage heat exchanger 204, a third-stage heat exchanger 205, a fourth-stage heat exchanger 206, a fifth-stage heat exchanger 207, a first-stage normal-para-hydrogen converter 214, a second-stage normal-para-hydrogen converter 215, and a third-stage normal-para-hydrogen converter 216. Each stage of the heat exchanger (203, 204, 205, 206, 207) and the normal-para-hydrogen converter (214, 215, 216) are A liquefied hydrogen channel 209 is provided, and the liquefied hydrogen channels 209 of the first-stage heat exchanger 203, the second-stage heat exchanger 204, the first-stage normal-parahydrogen converter 214, the third-stage heat exchanger 205, the second-stage normal-parahydrogen converter 215, the fourth-stage heat exchanger 206, the third-stage normal-parahydrogen converter 216, and the fifth-stage heat exchanger 207 are connected in sequence, and the outlet of the liquefied hydrogen channel of the fifth-stage heat exchanger 207 is connected to the first storage tank 217, and then the liquid hydrogen is stored in the liquid hydrogen storage tank 218 through the liquid hydrogen delivery pipe;

[0039] The helium refrigeration section includes: a gas-suspended centrifugal cryogenic compressor unit 201 (including in detail a primary compressor 4, a primary precooling heat exchanger 5, a secondary precooling heat exchanger 6, a secondary compressor 7, a primary precooling system 8, and a secondary precooling system 9), a cooler 202, a primary heat exchanger 203, a secondary heat exchanger 204, a third-stage heat exchanger 205, a fourth-stage heat exchanger 206, a fifth-stage heat exchanger 207, a helium throttle valve 210, a primary helium throttle valve 211, a primary turbine expander 208, a secondary turbine expander 209, a high-pressure pipeline 212, and a low-pressure pipeline 213. The high-pressure pipeline 212 of helium refrigeration is connected with the heat exchangers (203, 204, 205, 206, 207) of each stage in sequence, and the low-pressure pipeline 213 is connected with the heat exchangers (203, 204, 205, 206, 207) of each stage and the normal-parahydrogen converter (214, 215, 216) in sequence. The low-temperature and normal-pressure helium is first compressed by the primary compressor 4, and then enters the primary precooling heat exchanger 5 to exchange heat with the primary precooling system 8 for cooling, and then flows into the secondary precooling heat exchanger 6. In the secondary precooling heat exchanger 6, the helium is further cooled by exchanging heat with the secondary precooling system 9. The primary precooling system has the same circulation process as the first precooling system, but the equipment numbers are different. Similarly, the secondary precooling system has the same circulation process as the second precooling system, but the equipment numbers are different. The low-temperature helium after two-stage precooling enters the secondary compressor 7, and flows to the high-pressure pipeline 212 after being heated and pressurized. After being initially cooled by the cooler 202, the helium with reduced temperature continues to enter the secondary heat exchanger 204. The helium after passing through the secondary heat exchanger 204 is divided into two paths, one of which flows through the helium throttle valve 210, the first-stage turbine expander 208, the third-stage heat exchanger 205, and the second-stage turbine expander 209. The low-temperature helium coming out of the second-stage turbine expander 209 flows back to the low-pressure pipeline 213. The other helium passes through the third-stage heat exchanger 205, the fourth-stage heat exchanger 206, and the fifth-stage heat exchanger 207 in sequence, and then returns to the low-pressure pipeline 213 after being throttled by the first-stage helium throttle valve 211, and enters the low-pressure inlet of the compressor unit 201, completing the whole cycle.

[0040] In a preferred embodiment, the temperature of hydrogen at room temperature of 300K is reduced to 160-180K by the first precooling system of the precooling section 1, and the temperature is reduced to 130-120K by the second precooling system of the precooling section 3. The two-stage precooling greatly reduces the cooling time of hydrogen liquefaction and improves the system efficiency.

[0041] In a preferred embodiment, the gas-suspended centrifugal low-temperature compressor unit 201 is two two-stage compression type compressors 4 and 7 connected in series to complete four-stage compression. The low-temperature atmospheric pressure helium first enters the first-stage compressor 4 for compression, and then passes through the first-stage pre-cooler 5 and the first-stage pre-cooler 6, and exchanges heat with the first-stage pre-cooling system 8 and the second-stage pre-cooling system 9 to cool the helium, so that the helium at the inlet of the second-stage compressor 7 is in a low-temperature state, and the compressor effectively reduces the power consumption of the first-stage compressor 4 and the second-stage compressor 7.

[0042] In a preferred embodiment, the first-stage compressor 4, the second-stage compressor 7, the low-temperature compressor 104, the medium-temperature compressor 105, the high-temperature compressor 106, and the first-stage compressor 302 are all centrifugal compressors, supported by gas bearings or magnetic hybrid bearings, and have the advantages of small size, low noise, high efficiency, no need for lubricating oil, and maintenance-free.

[0043] In a preferred embodiment, the operating temperature of the low-pressure inlet of the compressor unit 201 is in the temperature range of 30~160K, and the power consumption of the compressor is significantly reduced compared with the normal temperature 300K working condition.

[0044] The utility model provides an air suspension centrifugal low temperature compressor unit 201, please refer to Figure 4 , including a primary compressor 4, a primary precooling heat exchanger 5, a secondary precooling heat exchanger 6, a secondary compressor 7, a primary precooling system 8, and a secondary precooling system 9, and its working method is as follows:

[0045] The low-temperature normal-pressure helium first enters the first-stage compressor 4 for compression, and then passes through the first-stage precooler 5 and the first-stage precooler 6, and exchanges heat with the first-stage precooling system 8 and the second-stage precooling system 9 to cool the helium, so that the helium at the inlet of the second-stage compressor 7 is in a low-temperature state. The gas-suspended centrifugal low-temperature compressor unit 201 uses two two-stage compression type compressors 4 and 7 connected in series to complete four-stage compression, and the first-stage precooling and the second-stage precooling are performed between the two compressors.

[0046] As a comparison with the gas suspension centrifugal low-temperature compressor for hydrogen liquefaction provided by the present invention, the gas suspension centrifugal normal temperature compressor unit 10 is shown in FIG. Figure 5 , including a primary normal temperature compressor 11 and a secondary normal temperature compressor 12, and its working mode is as follows:

[0047] 300K normal temperature and pressure helium is first compressed in two stages by a primary normal temperature compressor 11, and then enters a secondary normal temperature compressor 12 for two-stage compression. The air suspension centrifugal normal temperature compressor unit 10 uses two two-stage compression compressors 11, 12 connected in series to complete four-stage compression.

[0048] When the compressor efficiency, pressure ratio, and helium mass flow rate are the same, the comparison between normal temperature compression and low temperature compression is as follows:

[0049] Among them, the efficiency of the compressor is 75%, the suction pressure of the first-stage compressor is 1.1 bar, the pressure ratio of the first-stage compressor is 3.3, the pressure ratio of the second-stage compressor to the first-stage compressor is 3.3, the total pressure ratio is 12, and the helium mass flow rate is 0.1 kg / s:

[0050] When compression is performed at room temperature, the inlet temperature of the first-stage compressor is 300K, and the calculation results are:

[0051] The power of the first-stage compressor is 127.32 kW, the power of the second-stage compressor is 127.53 kW, and the total power is 254.85 kW;

[0052] (2) Using low temperature compression, the inlet temperature of the first-stage compressor is 160K, and the calculation results are:

[0053] The power of the first-stage compressor is 67.92kW, the power of the second-stage compressor is 68.15kW, and the total power is 136.07kW;

[0054] (3) Using low temperature compression, the inlet temperature of the first-stage compressor is 120K, and the calculation results are:

[0055] The power of the first-stage compressor is 50.96kW, the power of the second-stage compressor is 51.20kW, and the total power is 102.16kW;

[0056] (4) Using low temperature compression, the inlet temperature of the first-stage compressor is 30K, and the calculation results are:

[0057] The power of the first-stage compressor is 12.78kW, the power of the second-stage compressor is 12.94kW, and the total power is 25.72kW;

[0058] From the above calculation results, we can conclude that:

[0059] The lower the intake air temperature at the compressor unit inlet, the lower the power consumption of the compressor. When the intake air temperature is 30K, 120K, and 160K, the power consumption of the compressor is reduced by 90%, 60%, and 47% respectively compared with that at 300K.

[0060] In a preferred embodiment, the working fluids that can be used in the second precooling system and the secondary precooling system are air, nitrogen, neon, argon, etc.

[0061] In a preferred embodiment, the raw hydrogen is pure hydrogen, and purification of the raw hydrogen is not considered.

[0062] In a preferred embodiment, the helium refrigeration section includes five stages of heat exchangers (203, 204, 205, 206, 207), and each stage of heat exchangers is connected in sequence. The number of heat exchanger stages is not limited to five, and can be increased or decreased according to actual engineering cases.

[0063] In a preferred embodiment, hydrogen liquefaction includes three stages of the above-mentioned normal-para-hydrogen converters (214, 215, 216). The number of normal-para-hydrogen converters is not limited to three and can be increased or decreased according to actual engineering cases.

[0064] In a preferred embodiment, the catalyst in the normal-parahydrogen converter (214, 215, 216) is one of iron oxide, iron hydroxide, chromium dioxide, hydrous iron oxide, silica gel-supported nickel and silica gel-supported chromium oxide.

[0065] In a preferred embodiment, the low-temperature gas or low-temperature gas-liquid mixture at the outlet of the five-stage heat exchanger (203, 204, 205, 206, 207) first enters the first storage tank 217 through the liquefied hydrogen channel 219 for gas-liquid separation, and the gas flows back to the heat exchanger for further heat exchange and cooling, and the liquid hydrogen is stored in the liquid hydrogen storage tank 218 through the liquid hydrogen delivery pipe.

[0066] In a preferred embodiment, in the helium refrigeration process, the helium coming out of the secondary heat exchanger 204 is split into two paths, in which the high-pressure and low-temperature gas enters the helium throttle valve 210 for throttling and reducing the pressure, and the throttled and reduced-pressure gas enters the first-stage turbine expander 208 for expansion and cooling, and then passes through the third-stage heat exchanger 205 for further cooling, and the low-temperature gas enters the second-stage turbine expander 209 for cooling and reducing the pressure, and the low-temperature and low-pressure helium flows into the low-pressure inlet of the fourth-stage heat exchanger 206 to form low-temperature and low-pressure return gas. The cold energy generated in the whole process is used to cool the low-temperature and high-pressure helium to produce liquid helium.

Claims

1. A two-stage precooling hydrogen liquefaction device, characterized in that: include: Precooling section and liquefaction section; The precooling section includes: a first precooling system and a second precooling system; wherein the first precooling system includes: a low-temperature compressor, a medium-temperature compressor, a high-temperature compressor, a first-stage evaporative condenser, a second-stage evaporative condenser, a third-stage condenser, a first-stage throttling device, a second-stage throttling device, and a third-stage throttling device; the high-temperature and high-pressure gas at the outlet of the low-temperature compressor enters the condensation side of the first-stage evaporative condenser to release heat, and becomes a high-temperature liquid after heat release, and is expanded and throttled by the first-stage throttling device to produce a low-temperature and low-pressure liquid that flows into the first-stage heat exchanger of the liquefaction section, absorbs the heat of the normal-temperature hydrogen in the first-stage heat exchanger of the liquefaction section, and becomes a low-temperature gas, so that the normal-temperature hydrogen is precooled initially, and the low-temperature gas continues to flow into the inlet of the low-temperature compressor to realize the low-temperature cycle; the medium-temperature cycle realized by the medium-temperature compressor and the evaporation side of the first-stage evaporative condenser, the condensation side of the second-stage evaporative condenser, and the second-stage throttling device is the same as the above-mentioned low-temperature heat exchange process; similarly, The high-temperature cycle realized by the high-temperature compressor, the evaporation side of the secondary evaporative condenser, the third-stage condenser, and the third-stage throttling device is also consistent with the low-temperature cycle; the heat absorbed from the first-stage heat exchanger of the liquefaction section is released to the external environment by the third-stage condenser; The second precooling system includes: a first-stage compressor, an aftercooler, a booster compressor, a regenerator, and an expander; the high-temperature and high-pressure gas at the outlet of the first-stage compressor enters the aftercooler for cooling, the cooled gas enters the booster compressor to increase the pressure, and then enters the regenerator for heat exchange with the reflux gas, and then enters the expander for adiabatic expansion refrigeration, the low-temperature gas coming out of the expander is the hydrogen of the hydrogen liquefaction system for the second precooling, and the precooled gas enters the first-stage compressor after heat exchange in the regenerator, completing the entire second precooling system cycle; The liquefaction section includes: a hydrogen liquefaction section and a helium refrigeration section; wherein the hydrogen liquefaction section includes: a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a quaternary heat exchanger, a 5th heat exchanger, a primary para-hydrogen converter, a secondary para-hydrogen converter, and a tertiary para-hydrogen converter, each stage of the heat exchanger and the para-hydrogen converter is provided with a liquefied hydrogen channel, the primary heat exchanger, the secondary heat exchanger, the primary para-hydrogen converter, the tertiary heat exchanger, the secondary para-hydrogen converter, the 4th heat exchanger, the tertiary para-hydrogen converter, and the 5th heat exchanger are sequentially connected, the outlet of the liquefied hydrogen channel of the 5th heat exchanger is connected to the first storage tank, and then the liquid hydrogen is stored in the liquid hydrogen storage tank through the liquid hydrogen delivery pipe; The helium refrigeration section includes: a gas-suspended centrifugal cryogenic compressor unit, a cooler, a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, a quaternary heat exchanger, a 5th-stage heat exchanger, a helium throttle valve, a primary helium throttle valve, a primary turbine expander, a secondary turbine expander, a high-pressure pipeline, and a low-pressure pipeline; the high-pressure pipeline of helium refrigeration is connected with the heat exchangers at each stage in sequence, and the low-pressure pipeline is connected with the heat exchangers at each stage and the normal-parahydrogen converter in sequence; the low-temperature and normal-pressure helium enters the compressor unit, and flows to the high-pressure pipeline after being heated and pressurized. After preliminary cooling in the cooler, the helium with reduced temperature continues to enter the secondary heat exchanger. After passing through the secondary heat exchanger, the helium is split into two paths. One path flows through the helium throttle valve, the first-stage turbine expander, the third-stage heat exchanger, and the second-stage turbine expander. The low-temperature helium coming out of the second-stage turbine expander flows back to the low-pressure pipeline. The other path of helium passes through the third-stage heat exchanger, the fourth-stage heat exchanger, and the fifth-stage heat exchanger in turn, and then returns to the low-pressure pipeline through the first-stage helium throttle valve and enters the low-pressure inlet of the compressor unit to complete the whole cycle.

2. A two-stage precooling hydrogen liquefaction device as claimed in claim 1, characterized in that: The temperature of hydrogen at room temperature of 300K is reduced to 110~180K through the first precooling system, and then to 60~130K through the second precooling system. The two-stage precooling greatly reduces the cooling time of hydrogen liquefaction and improves the system efficiency.

3. A two-stage precooling hydrogen liquefaction device as claimed in claim 1, characterized in that: The helium refrigeration section gas suspension centrifugal low-temperature compressor unit is composed of two two-stage compression type compressors connected in series to complete four-stage compression. Primary precooling and secondary precooling are performed between the two compressors to keep the helium gas at the inlet of the second compressor in a low-temperature state. The precooling between the compressor stages effectively reduces the power consumption of the compressor.

4. A two-stage precooling hydrogen liquefaction device as claimed in claim 1, characterized in that: The compressors described in the entire system are all centrifugal compressors, supported by gas bearings or magnetic hybrid bearings.

5. A two-stage precooling hydrogen liquefaction device as claimed in claim 3, characterized in that: The operating temperature of the low-pressure inlet of the helium refrigeration section compressor unit is in the temperature range of 20~160K.

6. A two-stage precooling hydrogen liquefaction device as claimed in claim 1, characterized in that: The working fluids that can be used in the second precooling system and the secondary precooling system are air, nitrogen, neon, and argon.

7. A two-stage precooling hydrogen liquefaction device as claimed in claim 1, characterized in that: In the helium refrigeration process, the helium coming out of the secondary heat exchanger is split into two paths. In one path, the high-pressure and low-temperature gas enters the helium throttle valve for throttling and pressure reduction. The throttled and pressure-reduced gas enters the first-stage turbine expander for expansion and cooling, and then passes through the third-stage heat exchanger for further cooling. The low-temperature gas enters the second-stage turbine expander for cooling and pressure reduction. The low-temperature and low-pressure helium flows into the low-pressure inlet of the fourth-stage heat exchanger to form low-temperature and low-pressure return gas. The cold energy generated in the whole process is used to cool the low-temperature and high-pressure helium to produce liquid helium.

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