Pre-cooling and liquefying system of tandem type distributed regenerative refrigerating machine

Abstract

The invention relates to a pre-cooling and liquefying system of a tandem type distributed regenerative refrigerator. The pre-cooling and liquefying system comprises a refrigerating module and a distributed pre-cooling and liquefying module. The refrigeration module comprises a plurality of distributed refrigeration modules; the system further comprises a plurality of two-temperature-level refrigeration modules, and each distributed refrigeration module comprises a regenerative refrigerator unit. The regenerative refrigerator unit comprises a compression device, a regenerator and a cold end heat exchanger which are connected in sequence; the distributed pre-cooling and liquefying module comprises a distributed refrigerating capacity extracting device, a material source, an air supply pipeline, a feeding control mechanism and a liquid collecting assembly. Compared with the prior art, the distributed refrigerating capacity is extracted by introducing different working media into the refrigerating machine, generating the distributed refrigerating capacity in different temperature zones through the working media, utilizing direct current, arranging a discrete heat exchanger in the middle of a heat regenerator and the like so as to be used for cooling and liquefying low-temperature gas; sensible heat and latent heat of low-temperature gas are liquefied in different temperature zones respectively, energy can be saved, and the liquefaction efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of refrigeration technology, in particular to a multiple distributed cooling liquefied cryogenic gas system. BACKGROUND

[0002] Regenerative refrigerator is a kind of refrigeration technology in the form of alternating flow, which uses regenerator to realize the periodic heat storage and release between gas working medium and regenerator filler, and uses the expansion of gas to produce refrigeration effect. The regenerator generally has a large specific surface area per unit volume. Regenerative cryogenic refrigerator has the advantages of high reliability, simple structure, high flexibility, etc., and is widely used in gas liquefaction, superconducting and other low-temperature technologies.

[0003] The change of pressure enthalpy will cause the change of regenerative enthalpy, resulting in heat loss. The "surplus cold" can obtain a certain amount of cold in a certain temperature zone in the regenerator, but does not reduce the cold end refrigeration capacity. Early research uses a heat exchanger to convert enthalpy flow into surplus cold, and distributes the surplus cold outside the regenerator to liquefy gas, which significantly improves the liquefaction rate.

[0004] Temperature distribution type refrigeration cycle expands the range of gas types, temperatures, etc. Each gas such as helium, hydrogen, and nitrogen is used to form a distributed refrigeration capacity in the near-critical temperature zone, and the distributed refrigeration capacity is transmitted. Due to the temperature distribution, it is difficult to set up a heat exchanger like a two-temperature to obtain all the cold, and heat exchange along the temperature gradient is needed. The distributed cold can be transmitted and utilized through coiling or large wall surfaces.

[0005] Hydrogen, as a clean and renewable energy source, can be carbon-free, has multiple preparation methods and wide application prospects, and is a key component of future energy structure. Liquid hydrogen, due to its high energy density and good safety, is gradually becoming a key direction for the development of China's hydrogen energy industry. Many research institutions have begun to focus on the research of liquid hydrogen, but in the face of the high cost of large-scale liquefaction equipment and the challenges of liquid hydrogen transportation, it is urgent to develop small hydrogen liquefaction devices for experimental research, especially those that use liquid hydrogen as experimental medium. However, existing small-scale liquefaction devices have low refrigeration efficiency, limited liquefaction output, and high cost. Therefore, it is an important demand to develop a low-cost and efficient small hydrogen liquefaction device. Helium is a non-renewable gas, and its collection and liquefaction costs are high. The existing liquefaction method mainly builds large-scale helium liquefaction devices, but this method is expensive and suitable for situations where a large amount of helium is used. There are currently mobile small helium liquefaction equipment on the market, which mainly features pre-cooling cooling by wrapping the liquefaction pipeline around the regenerator. However, this method has high heat transfer resistance, low liquefaction efficiency, and high liquefaction cost. Therefore, a low-cost and efficient small helium liquefaction device is also needed. SUMMARY

[0006] The application aims at solving the problems of the prior art small-sized low-temperature gas liquefaction device, and provides a pre-cooling and liquefaction system of a series distributed regenerative refrigerator, different working media are introduced into the refrigerator, distributed refrigeration capacity is generated in different temperature zones, and the distributed refrigeration capacity is extracted by an inner direct flow device, an outer direct flow device or a plurality of discrete heat exchangers to pre-cool and liquefy low-temperature gas, and the sensible heat and latent heat of the gas are liquefied in different temperature zones, so that energy can be saved and liquefaction efficiency can be improved. In order to solve the above problems, the technical scheme adopted by the application is:

[0007] The technical scheme aims at protecting a pre-cooling and liquefaction system of a series distributed regenerative refrigerator, and the system comprises a refrigeration module and a distributed pre-cooling and liquefaction module.

[0008] The refrigeration module comprises two or more refrigeration modules as distributed refrigeration modules, and the refrigeration temperature gradually decreases, and the refrigeration module further comprises zero, one or more two-temperature refrigeration modules.

[0009] The refrigeration module comprises the same or different regenerative refrigerator units;

[0010] The regenerative refrigerator unit comprises a compression device, a regenerator and a cold-end heat exchanger connected in sequence.

[0011] The distributed pre-cooling and liquefaction module comprises a distributed refrigeration capacity extraction device, a material source, a feeding pipeline, a feeding control mechanism and a liquid collection assembly.

[0012] The distributed refrigeration capacity extraction device is a discrete heat exchanger, an outer direct flow or an inner direct flow heat exchange pipeline.

[0013] The pre-cooled and liquefied material passes through two or more refrigeration modules with gradually decreasing temperatures in sequence.

[0014] Further, the heat exchange pipe is arranged on the cold head of the refrigerator.

[0015] The heat exchange pipe is a metal pipe for realizing heat exchange between internal and external fluids, and the form includes a finned tube, a coil pipe or other pipes.

[0016] Further, different working media with different pressures or different types of working media are introduced into the regenerative refrigerator.

[0017] The regenerative refrigerator can be two refrigeration modules, three refrigeration modules or more refrigeration modules.

[0018] The working media can generate distributed refrigeration capacity in the corresponding temperature zone.

[0019] Further, the regenerative refrigerator comprises one or more of GM refrigerator, Solvay refrigerator, Stirling refrigerator, VM refrigerator, pulse tube refrigerator in a multi-stage coupling hybrid structure.

[0020] The regenerative refrigerator can be one-stage, two-stage or higher stage.

[0021] The pulse tube refrigerator is a GM type pulse tube refrigerator or a Stirling type pulse tube refrigerator.

[0022] Further, the low-temperature gas is hydrogen, helium, neon, nitrogen, oxygen, argon, krypton, methane or a mixture of these gases and other gases.

[0023] Further, the average working pressure in the regenerative refrigeration module is generally greater than 1 times atmospheric pressure (absolute pressure), and in special cases can be extended to below atmospheric pressure, taking 0.1-2000 times atmospheric pressure (i.e. 0.01-200 MPa pressure range), the working pressure of the pre-cooling and liquefaction module is generally different from that in the regenerative refrigeration module, and is usually close to atmospheric pressure (absolute pressure), but in a high-pressure low-temperature gas storage system, a high pressure can be achieved, so it can include 0.01 to 2000 times atmospheric pressure (i.e. 0.001-200 MPa pressure range).

[0024] The distributed cold energy transmission system comprises an outer direct current device, an inner direct current device or a plurality of discrete heat exchangers, and the distributed refrigeration capacity is transmitted by direct current transmission to improve the liquefaction efficiency.

[0025] Further, the feed source is a gas or liquid at normal temperature and high pressure or at normal temperature and normal pressure. The feed control mechanism comprises a pressure reducing valve and a feed control valve, and the collection assembly is a liquid low-temperature gas storage tank.

[0026] Further, the gas pressure in the feed line is adjusted by the pressure reducing valve according to the target value, and the saturation temperature can be increased by increasing the gas pressure, and the required refrigeration capacity can be reduced.

[0027] Further, the inner direct current device can have an expansion mechanism. The expansion mechanism is one of a single expansion mechanism, a plurality of expansion mechanisms in series, a plurality of expansion mechanisms in parallel, and a plurality of expansion mechanisms in series and parallel combination; and the position of the expansion mechanism on the direct current is the cold end or any position between the cold end and the hot end.

[0028] The expansion mechanism comprises one of a small hole valve, a small hole, a capillary tube, a slit, and a porous medium to achieve throttling and pressure reduction by frictional resistance and local resistance.

[0029] The expansion mechanism further comprises a turbine expander, a piston expander and other mechanisms that achieve pressure reduction by external work.

[0030] The buffer gas reservoir is arranged after the expansion mechanism, and the buffer gas reservoir is arranged at any position between the expansion mechanism and the compression mechanism.

[0031] The direct current is depressurized by the expansion mechanism, so that the specific heat capacity of the gas in the direct current is close to the specific heat capacity of the pre-cooled material, and the expansion refrigeration effect is generated, thereby improving the cold end refrigeration capacity.

[0032] Further, the application provides a pre-cooling and liquefaction method of a series distributed regenerative refrigerator, which is specifically as follows:

[0033] Firstly, different working substances are respectively introduced into the first, second and third regenerative refrigerators, the working substances can generate distributed cold energy at the corresponding working temperature of the refrigerator, and the refrigerator is started.

[0034] Then, the gas flow in the feed pipe is adjusted to a set value through the mass flow meter and the adjusting valve, and the gas in the high-pressure gas cylinder is reduced to micro-positive pressure by the pressure reducing valve and then enters the multiple refrigeration modules and the distributed pre-cooling and liquefaction system.

[0035] In the multiple refrigeration modules and the distributed pre-cooling and liquefaction modules, the gas first passes through the first distributed cold energy transmission device and exchanges heat, completes the first-stage cooling, and the temperature is reduced for the first time, for example, liquid nitrogen can be introduced, and the distributed cold energy generated by the liquid nitrogen is used to cool the gas to the liquid nitrogen temperature zone; then the gas passes through the second distributed cold energy transmission device and exchanges heat, completes the second-stage cooling, and the temperature continues to decrease, for example, liquid hydrogen can be introduced, and the distributed cold energy generated by the liquid hydrogen is used to cool the gas to the liquid hydrogen temperature zone; then the gas passes through the third refrigeration module and exchanges heat, and the cold energy is used for continuous liquefaction. The sensible heat of the gas in the first two stages of cooling and the latent heat of the gas in the third stage of cooling. After completion of liquefaction, the gas in the liquid state enters the storage tank.

[0036] Compared with the prior art, the application has the following technical advantages:

[0037] 1) Compared with the conventional single-stage refrigeration system, the low-temperature gas is liquefied by adopting multiple distributed multistage refrigeration, the temperature is gradually reduced, the sensible heat and the latent heat of the low-temperature gas are respectively liquefied, the entropy production of each stage of refrigeration is reduced, and the efficiency is improved.

[0038] 2) Different gases are used to generate distributed cold energy in different temperature zones, the distributed cold energy is transmitted in the form of internal direct current, external direct current or multiple discrete heat exchangers, the distributed cold energy is used to liquefy the low-temperature gas, and the liquefaction efficiency of the gas is improved.

[0039] 3) The use of primary or secondary refrigerators, according to different temperature zones, different refrigeration power exists in the refrigerator, through the cascade utilization of cold energy, the refrigeration power of the refrigerator is used to the maximum extent. If the first section uses nitrogen to generate distributed cold energy, the low-temperature gas can be directly cooled from room temperature to the liquid nitrogen temperature zone, improving the efficiency, and the nitrogen is easy to obtain, reducing the cost.

[0040] 4) The pressure of the gas to be liquefied is in micro-positive pressure, without high requirements for the sealing and pressure resistance of the system, while effectively preventing the external oxygen-containing air from entering the liquefaction device, which can significantly improve the operation safety of the device. Through the pressure reducing valve, mass flow meter and control valve, the state of gas inflow can be controlled, the direct current is more stable, and the distributed cold energy can be more fully utilized.

[0041] 5) The regenerator in the application can absorb a certain amount of enthalpy flow, especially when the working medium is close to the critical temperature zone, within a certain range of direct current size, the actual COP of the regenerator is affected by the direct current and decreases very little.

[0042] 6) The precooling and liquefaction system of the series distributed regenerative refrigerator in the application can be applied to small and large systems of two refrigerators or multiple refrigerators, and can be applied to hydrogen, helium, neon, nitrogen, oxygen, argon, krypton, methane or mixtures composed of these gases and other gases as working medium, and has wide application prospect.

[0043] 7) The low-temperature liquid generated by the precooling and liquefaction system of the series distributed regenerative refrigerator in the application can be used as a constant-temperature cold source to meet the stable and constant-temperature low-temperature demand. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a structure schematic view of the precooling and liquefaction hydrogen system of the series distributed regenerative refrigerator of the application example 1 using the internal direct current mode and the GM refrigerator.

[0045] In the figure: compression device-1, compressor low-pressure gas storage tank-2, compressor cooler and filter device-3, compressor high-pressure gas storage tank-4, GM type compressor high-low pressure gas distribution valve-5, refrigerator inlet channel-6, refrigerator cylinder-7, first-stage regenerator-8, first-stage expansion piston sealing mechanism-9, first-stage expansion piston and cylinder gap-10, first-stage expansion piston-11, first-stage cold end heat exchanger-12, first-stage expansion cavity-13; second-stage expansion piston sealing mechanism-14, second-stage expansion piston and cylinder gap-16, second-stage expansion piston-17, second-stage expansion cavity-18, cold end heat exchange assembly 19, second-stage regenerator-20.

[0046] Figure 2Figure 1 is a schematic diagram of a pre-cooling and liquefying system of a series distributed regenerative refrigerator of Example 2 of the present application, which uses an external direct current mode and a GM pulse tube refrigerator.

[0047] Figure 1 is a schematic diagram of a pre-cooling and liquefying system of a series distributed regenerative refrigerator of Example 2 of the present application, which uses an external direct current mode and a GM pulse tube refrigerator. DETAILED DESCRIPTION

[0048] In general, the pre-cooling and liquefying system of the series distributed regenerative refrigerator in the present application includes a refrigeration module and a distributed pre-cooling and liquefying module. The refrigeration module includes two or more distributed refrigeration modules, which have gradually reduced refrigeration temperatures, and zero, one or more two-temperature refrigeration modules. The refrigeration module includes a plurality of same or different regenerative refrigerator units, which include a compression device 1, a regenerator and a cold end heat exchanger 12 connected in sequence.

[0049] In a specific implementation, the distributed pre-cooling and liquefying module includes a distributed refrigeration amount transmission device 26, a material source 22, a feed control mechanism 23, a gas supply pipeline 24 and a liquid collection assembly 21.

[0050] In a specific implementation, the distributed refrigeration amount extraction device includes a gas supply pipeline coiled on the regenerator or a heat exchange pipeline in the regenerator. After the gas flows out of the gas cylinder, it is liquefied through the distributed cold amount transmission system and flows into the liquid gas storage tank. The stable flow of the gas can be controlled through the flow meter and the control valve.

[0051] In specific implementation, the regenerative refrigeration unit is a refrigeration unit that uses regenerator components to achieve alternating storage and release of heat; the regenerative refrigeration unit includes a hybrid structure of one or more refrigeration units selected from GM refrigeration units, Solvay refrigeration units, Stirling refrigeration units, VM refrigeration units, and pulse tube refrigeration units, coupled in multiple stages; the pulse tube refrigeration unit is either a GM type pulse tube refrigeration unit or a Stirling type pulse tube refrigeration unit. The regenerative refrigeration module has an internal regenerator structure or an external regenerator structure; in the internal regenerator structure, the regenerator is built into the expansion piston; in the external regenerator structure, the expansion piston and the regenerator are separate units; the regenerative refrigeration module includes single-stage structures and multi-stage coupling structures, and the multi-stage coupling structures include multi-stage thermal coupling structures, multi-stage gas coupling structures, and hybrid structures of thermal coupling and gas coupling.

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment is a schematic diagram of a series-connected distributed cooling high-efficiency precooling and liquefaction hydrogen system using an internal DC method and GM refrigerators. It includes three GM refrigerator refrigeration modules and a distributed precooling and liquefaction module.

[0055] The three GM refrigeration modules each include three regenerative refrigeration units. Each of the three regenerative refrigeration units includes a compressor unit 1, a low-pressure compressor receiver 2, a compressor cooler and filter 3, a high-pressure compressor receiver 4, high and low pressure distribution valves for the GM compressor 5, an air intake passage for the refrigeration unit 6, a cylinder for the refrigeration unit 7, a first-stage regenerator 8, a first-stage expansion piston sealing mechanism 9, a gap between the first-stage expansion piston and the cylinder 10, a first-stage expansion piston 11, a first-stage cold-end heat exchanger 12, and a first-stage expansion chamber 13. The three regenerative refrigerant units also include two two-stage GM refrigeration units. Each two-stage GM refrigeration unit further includes a second-stage expansion piston 17, a second-stage regenerator 20, a second-stage expansion piston sealing mechanism 14, a gap between the second-stage expansion piston and the cylinder 16, a second-stage cold-end heat exchanger, and a second-stage expansion chamber 18.

[0056] Among them, the compression device 1 is a compressor or existing mainstream compression equipment, and the compressor cooler and the filter device 3 are water-cooled, capillary filter and physical adsorption filter.

[0057] The distributed pre-cooling and liquefaction module comprises, in sequence, a gas source 22, an inlet gas control mechanism 23, a hydrogen supply pipeline 24, a cold end heat exchange assembly 19, a liquid collection assembly 21 and a distributed cold energy transmission device, wherein the distributed transmission device comprises an inner direct current pipeline 25, a counterflow heat exchanger 26, an expansion mechanism 27, a direct current control valve 28, a low-pressure buffer gas reservoir 29, a compression mechanism 30, a compression mechanism cooler and a filtering device 31.

[0058] The gas source 22 is a compressed gas storage tank or other pressure container, the inlet gas control mechanism 23 is a flow regulating valve, the cold end heat exchange assembly 19 is a slit copper heat exchanger, and the liquid collection assembly 21 is a liquid hydrogen storage tank.

[0059] The working process of the embodiment is as follows:

[0060] The system is installed according to the above process, and a gas working substance at a certain working pressure is filled into the two refrigerators, nitrogen or oxygen or other gas in the first refrigerator, hydrogen or other gas in the second refrigerator, and helium in the third refrigerator. The same compressor 1 in the three refrigerators is started first, and the two refrigerators start to cool. When the temperature of the regenerator cold end heat exchanger is reduced to below the required temperature, the opening of the inlet control mechanism is adjusted, and the hydrogen to be liquefied is introduced to liquefy the hydrogen.

[0061] Nitrogen will generate distributed cold energy in the liquid nitrogen temperature zone. Hydrogen passes through the distributed cold energy transmission device of the first refrigeration module, exchanges heat with the direct current passing through the first refrigerator in the counterflow heat exchanger, and extracts the distributed cold energy in the form of an inner direct current to cool down. The direct current will pass through the expansion mechanism during circulation, and the pressure is reduced after the expansion mechanism, which on the one hand makes the specific heat capacity of the gas in the direct current close to that of the pre-cooled material, and on the other hand generates an expansion refrigeration effect to improve the cold end refrigeration capacity. Then it flows into the refrigerator cold head, and the sensible heat and conversion heat released in the process are liquefied by the refrigerator cold head and the extracted distributed cold energy. When flowing through the first refrigerator, the temperature of the hydrogen is reduced to about 77K in the liquid nitrogen temperature zone.

[0062] Hydrogen will generate distributed cold energy in the liquid hydrogen temperature zone. After the hydrogen to be liquefied flows through the first refrigerator, it flows into the second refrigerator. The hydrogen passes through the distributed cold energy transmission device of the second refrigeration module, exchanges heat with the direct current passing through the second refrigerator in the counterflow heat exchanger, and then passes through the cold head and the normal hydrogen conversion device. The sensible heat and conversion heat of the hydrogen to be liquefied are liquefied by the extracted distributed cold energy and the cold head. When flowing through the second refrigerator, the temperature of the hydrogen is reduced to about 20K in the liquid hydrogen temperature zone, and a part of the hydrogen is converted into liquid hydrogen.

[0063] Helium exhibits properties similar to an ideal gas in the liquid hydrogen temperature range, resulting in high refrigeration efficiency. After the liquefied hydrogen gas flows through the second refrigeration unit, it enters the secondary cooling head of the third refrigeration unit. The latent heat of the liquefied hydrogen gas, provided by the secondary cooling head, completely cools the gas-liquid mixture into liquid hydrogen, which then flows into the liquid hydrogen storage tank.

[0064] The distributed heat load of hydrogen includes sensible heat, which may or may not include conversion heat, and may or may not require the installation of a hydrogen conversion device.

[0065] Example 2

[0066] like Figure 2 As shown, this embodiment is a schematic diagram of a series-connected distributed cooling high-efficiency precooling and liquefaction hydrogen system using an external DC method and a GM-type pulse tube refrigerator. It includes two GM-type pulse tube refrigerator refrigeration modules, one GM refrigerator refrigeration module, and a distributed precooling and liquefaction module.

[0067] The two GM-type pulse tube refrigeration modules include two regenerative refrigeration units, consisting of one primary GM pulse tube refrigeration unit and one secondary GM pulse tube refrigeration unit. The compression units of the two regenerative refrigeration units consist of a scroll compressor 26, a high-pressure control valve 27, and a low-pressure control valve 28. They also include a refrigeration unit inlet passage 6, a refrigeration unit cylinder 7, a first-stage regenerator 8, a first-stage cold-end heat exchanger 12, a first-stage regenerator and expansion mechanism (pulse tube) transmission pipe 29, a first-stage expansion mechanism (pulse tube) cold-end heat exchanger 30, a first-stage expansion mechanism (pulse tube) 31, a first-stage expansion mechanism (pulse tube) hot-end heat exchanger 32, and a phase-adjusting gas reservoir 33. The second regenerative refrigerant unit includes a two-stage GM pulse tube refrigeration unit. The two-stage GM pulse tube refrigeration unit also includes a second-stage cold-end heat exchanger, a second-stage regenerator and expansion mechanism (pulse tube) transmission pipe 34, a second-stage expansion mechanism (pulse tube) cold-end heat exchanger 35, a second-stage expansion mechanism (pulse tube) 36, a second-stage expansion mechanism (pulse tube) hot-end heat exchanger 37, and a discrete heat exchanger 38.

[0068] The distributed precooling and liquefaction module includes a gas source 22, an air intake control mechanism 23, a cold end heat exchange component 19, a liquid collection component 21, and a distributed cold energy transmission device connected in sequence, wherein the distributed transmission device is an external DC heat exchange pipeline 25 coiled on the regenerator.

[0069] Among them, the gas source 22 is a compressed gas storage tank or other pressure vessel, the air intake control mechanism 23 is a flow regulating valve, the cold end heat exchange component 19 is a slit-type copper heat exchanger, and the liquid collection component 21 is a liquid hydrogen storage tank.

[0070] The distributed heat load of hydrogen includes sensible heat, which may or may not include conversion heat, and may or may not require the installation of a hydrogen conversion device.

[0071] The working process of the embodiment is as follows:

[0072] The system installation is completed according to the above process, and the gas working substance with a certain working pressure is filled into the two refrigerators, nitrogen or oxygen or other gas in the first refrigerator, hydrogen or other gas in the second refrigerator, and helium in the third refrigerator. The same compressor 1 in the three refrigerators is started first, and the two refrigerators start to cool. When the temperature of the heat exchanger at the cold end of the regenerator is reduced to below the required temperature, the opening of the feed control mechanism is adjusted, and the hydrogen to be liquefied is introduced. The hydrogen is liquefied.

[0073] The nitrogen produces distributed cold energy in the liquid nitrogen temperature zone. The hydrogen passes through the distributed cold energy transmission device of the first refrigeration module, which is a heat exchange pipe coiled on the refrigerator. The hydrogen exchanges heat with the first refrigerator in the heat exchange pipe, extracts the distributed cold energy in the form of external direct current to cool, and then flows into the cold head of the refrigerator. The sensible heat and conversion heat released in the process are liquefied by the cold head of the refrigerator and the extracted distributed cold energy. When flowing through the first refrigerator, the temperature of the hydrogen is reduced to about 77K in the liquid nitrogen temperature zone.

[0074] The hydrogen produces distributed cold energy in the liquid hydrogen temperature zone. After the hydrogen to be liquefied flows through the first refrigerator, it flows into the second refrigerator. The hydrogen passes through the distributed cold energy transmission device of the second refrigeration module, which is a heat exchange pipe coiled on the refrigerator. The hydrogen exchanges heat with the second refrigerator in the heat exchange pipe, extracts the distributed cold energy in the form of external direct current to cool, and then passes through the cold head and the normal hydrogen conversion device. The sensible heat and conversion heat of the liquefied hydrogen are liquefied by the extracted distributed cold energy and the cold energy of the cold head. When flowing through the second refrigerator, the temperature of the hydrogen is reduced to about 20K in the liquid hydrogen temperature zone, and a part of the hydrogen is converted into liquid hydrogen.

[0075] The helium has similar properties to ideal gas in the liquid hydrogen temperature zone, and the refrigeration efficiency is high. After the hydrogen to be liquefied flows through the second refrigerator, it flows into the two-stage cold head of the third refrigerator. The latent heat of the hydrogen is liquefied by the cold energy provided by the two-stage cold head, the gas-liquid mixture is completely cooled to become liquid hydrogen, and then flows into the liquid hydrogen storage tank.

[0076] The external heat exchanger in the first refrigerator and the second refrigerator can transmit distributed cold energy in a single or multiple heat conduction mode. The discrete heat exchanger in the figure represents the transmission of distributed cold energy.

[0077] The above-described embodiment is only a preferred scheme of the present application, but it is not intended to limit the present application. Various changes and modifications can be made. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A pre-cooling and liquefaction system for a series-connected distributed regenerative refrigerator, characterized by, The refrigeration module and the distributed pre-cooling and liquefaction module are included. The refrigeration module includes a plurality of refrigeration modules, and the refrigeration module is a distributed refrigeration module, the refrigeration temperature of the plurality of distributed refrigeration modules gradually decreases, and at least one two-temperature refrigeration module is further included. The distributed refrigeration module is a regenerative refrigerator unit. The regenerative refrigerator unit includes a compression device, a regenerator, and a cold-end heat exchanger connected in sequence. The distributed pre-cooling and liquefaction module includes a distributed refrigeration amount extraction device, a material source, a feeding pipeline, a feeding control mechanism, and a liquid collection assembly. The distributed refrigeration amount extraction device is a discrete heat exchange type, an external straight flow, and an internal straight flow heat exchange pipeline. The pre-cooled and liquefied material sequentially passes through a plurality of distributed refrigeration modules with gradually decreasing temperatures.

2. A pre-cooling and liquefaction system for a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, The heat exchange pipe is mounted on the refrigerator cold head. The heat exchange pipe is a metal pipe for realizing heat exchange between internal and external fluids, and the metal pipe is in the form of a finned tube or a coil.

3. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, Different working fluids with different pressures or different types of working fluids are respectively introduced into a plurality of regenerative refrigerator units. The regenerative refrigeration module includes two refrigeration modules, three refrigeration modules, or more refrigeration modules. The working fluid generates a distributed refrigeration amount in the corresponding temperature zone.

4. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, The regenerative refrigerator includes a GM refrigerator, a Solvay refrigerator, a Stirling refrigerator, a VM refrigerator, and a pulse tube refrigerator in one or more refrigerators in a multi-stage coupling mixed structure. The regenerative refrigerator is a one-stage or multi-stage regenerative refrigerator. The pulse tube refrigerator is a GM type pulse tube refrigerator or a Stirling type pulse tube refrigerator.

5. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, The low-temperature gas used is a mixture of one or more of hydrogen, helium, neon, nitrogen, oxygen, argon, krypton, and methane.

6. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, The average working pressure in the two or more refrigeration modules is 0.1 to 2000 times atmospheric pressure. The working pressure of the distributed pre-cooling and liquefaction module is 0.01 to 2000 times atmospheric pressure. The distributed pre-cooling and liquefaction module includes a distributed cold amount transmission system. The distributed cold amount transmission system is selected from one of an internal straight flow device, an external straight flow device, or a plurality of discrete heat exchangers.

7. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 1, characterized in that, The material source is a gas or a liquid at normal temperature and high pressure or at normal temperature and normal pressure. The feeding control mechanism includes a pressure reducing valve and a feeding control valve. The liquid collection assembly is a liquid low-temperature gas storage tank.

8. A precooling and liquefaction system for a series-connected distributed regenerative refrigerator according to claim 7, characterized in that, The low-temperature gas pressure in the feeding pipeline is adjusted by the pressure reducing valve according to the target value, the saturation temperature is increased by increasing the gas pressure, and the required refrigerator cold amount is reduced.

9. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 6, characterized in that, The internal straight flow device is matched with an expansion mechanism. The expansion mechanism is one of a single expansion mechanism, a plurality of expansion mechanisms connected in series, a plurality of expansion mechanisms connected in parallel, or a plurality of expansion mechanisms connected in series and parallel. The position of the expansion mechanism on the straight flow is the cold end or any position between the cold end and the hot end. The expansion mechanism includes one of a small hole valve, a small hole, a capillary tube, a slit, and a porous medium to achieve throttling and pressure reduction through frictional resistance and local resistance.

10. The precooling and liquefaction system of a series-connected distributed regenerative refrigerator according to claim 9, characterized in that, The expansion mechanism further includes a turbine expander and a piston expander. The buffer gas reservoir is arranged at any position between the expansion mechanism and the compression mechanism. The direct current is depressurized by the expansion mechanism, so that the specific heat capacity of the gas in the direct current is close to the specific heat capacity of the pre-cooled material, and the expansion refrigeration effect is generated to improve the cold-end refrigeration capacity.

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