Cryogenic gas cooling system and method
By using a dual cooling system of pre-cooled refrigerant and main refrigerant in the low-temperature gas liquefaction system, heat exchange is used to exchange heat, and the problem of low energy efficiency of the existing system is solved, and a more efficient low-temperature gas liquefaction process is achieved.
Patent Information
- Application Number
- CN202380052375.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-06-06
- Filing Date
- 2023-06-05
- Publication Date
- 2025-04-08
AI Technical Summary
Existing low-temperature gas liquefaction systems have low energy efficiency, especially due to the low molecular weight and low viscosity of hydrogen and helium, which causes the compressor to consume a lot of energy.
The dual cooling system of pre-cooled refrigerant and main refrigerant is adopted to exchange heat through the pre-cooled heat exchanger and the liquefier heat exchanger to reduce the energy consumption of the main refrigerant compressor.
It effectively reduces the energy consumption during the liquefaction of low-temperature gases, improves the energy efficiency of the system, and reduces the consumption of nitrogen.
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Figure CN119790273A_ABST
Abstract
Description
[0001] Priority claim
[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 349,354, filed on June 6, 2022, the contents of which are incorporated herein by reference. Technical Field
[0003] The present disclosure generally relates to systems and methods for refrigerating or liquefying cryogenic gases using cryogenic gases, and more particularly, to systems and methods for cooling cryogenic gases including a cryogenic liquid pre-cooling circuit. Background Art
[0004] Industrial cryogenic gases, such as natural gas, hydrogen, neon or helium, are advantageously stored or transported in liquid form because they occupy a much smaller volume (e.g., natural gas is 1 / 600 of the gaseous state). The liquefied gas is then evaporated back into the gaseous state for use in a location or system. The same cryogenic gases are also used in refrigerators, which are typically used in particle accelerator research, space temperature simulations, low-speed particle analysis (cold neutron sources) or other scientific applications. However, such refrigerators typically gasify the evaporated nitrogen into the atmosphere after the liquid nitrogen is heated to provide refrigeration, thereby consuming nitrogen.
[0005] The liquefaction of cryogenic gases is generally expensive. For example, gaseous hydrogen is converted into liquefied hydrogen by cooling it to about -253°C. Therefore, the typical cooling process utilizes a large amount of energy. In addition, the process may include multiple refrigeration cycles and involve multiple stages of gas compression.
[0006] Hydrogen liquefaction systems typically include a hydrogen refrigerant cycle using a compressor. Due to its low molecular weight and low viscosity, hydrogen is difficult to compress. Therefore, such compressors typically consume most of the energy required to operate the system. Likewise, the cost of compressing helium is also high. Cryogenic gas liquefaction systems and methods need to be more energy efficient. Summary of the invention
[0007] Several aspects of the subject matter may be implemented individually or together in the methods, devices, and systems described and claimed below. These aspects may be used alone or in combination with other aspects of the subject matter described herein, and the description of these aspects is not intended to exclude the individual use of these aspects or the individual claims of these aspects or the different combinations set forth in the appended claims.
[0008] In one aspect, a system for liquefying a cryogenic gas feed stream includes a precooling heat exchanger including a precooling refrigerant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a feed gas cooling passage. The precooling refrigeration circuit includes a precooling compressor configured to receive and compress precooling refrigerant vapor from the precooling refrigerant heating passage of the precooling heat exchanger, a precooling cooling device configured to receive and cool the compressed precooling refrigerant from the precooling compressor, a precooling expansion device configured to receive and expand the compressed and cooled precooling refrigerant from the precooling cooling device, and a precooling separation device configured to receive the expanded precooling refrigerant from the precooling expansion device under reduced pressure so as to reduce the boiling point of the expanded precooling refrigerant and separate the expanded precooling refrigerant into a precooling refrigerant vapor flow and a precooling refrigerant liquid flow. The precooling separation device has a vapor outlet and a liquid outlet fluidly connected to the precooling refrigerant heating passage of the precooling heat exchanger.
[0009] The liquefier heat exchanger includes a main refrigerant cooling passage, a main refrigerant heating passage, and a feed gas cooling passage. The main refrigeration circuit includes a first main compressor configured to receive and compress main refrigerant vapor from the main refrigerant heating passage of the liquefier heat exchanger and the precooling heat exchanger. The main cooling device is configured to receive and cool the compressed main refrigerant from the first main compressor, wherein the main cooling device has an outlet in fluid communication with the main refrigerant cooling passage of the precooling heat exchanger and the liquefier heat exchanger. The first main expansion device is configured to receive and expand the compressed and cooled main refrigerant from the main refrigerant cooling passage of the liquefier heat exchanger, wherein the first main expansion device has an outlet in fluid communication with the main refrigerant heating passage of the liquefier heat exchanger and the precooling heat exchanger.
[0010] The precooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel of the precooling heat exchanger and the low-temperature gas in the feed gas cooling channel are cooled by the precooling refrigerant in the precooling refrigerant heating channel and the main refrigerant in the main refrigerant heating channel. The liquefier heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel is cooled, and the low-temperature fluid in the feed gas cooling channel is liquefied by the main refrigerant in the main refrigerant heating channel.
[0011] On the other hand, a method for liquefying a cryogenic gas feed stream includes the steps of precooling the cryogenic gas feed stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream and liquefying the precooled cryogenic fluid stream using the main refrigerant. A heated precooling refrigerant is formed by the precooling step, and the precooling and liquefying steps form a heated main refrigerant. The method also includes the steps of compressing the heated precooling refrigerant to form a compressed precooling refrigerant, cooling the compressed precooling refrigerant to form a cooled precooling refrigerant, expanding the cooled precooling refrigerant to form an expanded precooling refrigerant; reducing the pressure of the expanded precooling refrigerant, thereby reducing the boiling point of the precooling refrigerant, separating the precooling refrigerant into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream, evaporating the precooling refrigerant liquid stream during precooling, and heating the precooling refrigerant vapor stream during precooling. The method further includes the steps of compressing the heated main refrigerant to form a compressed main refrigerant, cooling the compressed main refrigerant to form a cooled main refrigerant, and expanding the cooled main refrigerant to form an expanded main refrigerant, which is heated during the pre-cooling and liquefaction steps.
[0012] The method also includes using the liquefied gas fed to the phase separator 136 as a pre-cooling refrigerant which is vaporized in the illustrated heat exchanger 46. In the case of liquid nitrogen which is normally vented to the atmosphere, a vacuum pump (or ejector) 124 is required to obtain reduced pressure.
[0013] On the other hand, a system for cooling a cryogenic gas feed stream includes a precooling heat exchanger including a precooling refrigerant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a feed gas cooling passage. The precooling refrigeration circuit includes a precooling compressor configured to receive and compress precooling refrigerant vapor from the precooling refrigerant heating passage of the precooling heat exchanger, a precooling cooling device configured to receive and cool the compressed precooling refrigerant from the precooling compressor, a precooling expansion device configured to receive and expand the compressed and cooled precooling refrigerant from the precooling cooling device, and a precooling separation device configured to receive the expanded precooling refrigerant from the precooling expansion device under reduced pressure so as to reduce the boiling point of the expanded precooling refrigerant and separate the expanded precooling refrigerant into a precooling refrigerant vapor flow and a precooling refrigerant liquid flow. The precooling separation device has a vapor outlet and a liquid outlet fluidly connected to the precooling refrigerant heating passage of the precooling heat exchanger.
[0014] The cooling heat exchanger includes a main refrigerant cooling passage, a main refrigerant heating passage, and a feed gas cooling passage. The main refrigeration circuit includes a first main compressor configured to receive and compress main refrigerant vapor from the cooling heat exchanger and the main refrigerant heating passage of the precooling heat exchanger. The main cooling device is configured to receive and cool compressed main refrigerant from the first main compressor, wherein the main cooling device has an outlet in fluid communication with the main refrigerant cooling passage of the precooling heat exchanger and the cooling heat exchanger. The first main expansion device is configured to receive and expand compressed and cooled main refrigerant from the main refrigerant cooling passage of the cooling heat exchanger, wherein the first main expansion device has an outlet in fluid communication with the main refrigerant heating passage of the cooling heat exchanger and the precooling heat exchanger.
[0015] The precooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel of the precooling heat exchanger and the low-temperature gas in the feed gas cooling channel are cooled by the precooling refrigerant in the precooling refrigerant heating channel and the main refrigerant in the main refrigerant heating channel. The cooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel is cooled, and the low-temperature fluid in the feed gas cooling channel is cooled by the main refrigerant in the main refrigerant heating channel.
[0016] On the other hand, a method for cooling a cryogenic gas feed stream includes the steps of precooling the cryogenic gas feed stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream, and cooling the precooled cryogenic fluid stream using the main refrigerant. A heated precooling refrigerant is formed by the precooling step, and a heated main refrigerant is formed by the precooling and liquefying steps. The method also includes the steps of compressing the heated precooling refrigerant to form a compressed precooling refrigerant, cooling the compressed precooling refrigerant to form a cooled precooling refrigerant, expanding the cooled precooling refrigerant to form an expanded precooling refrigerant; reducing the pressure of the expanded precooling refrigerant, thereby reducing the boiling point of the precooling refrigerant, separating the precooling refrigerant into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream, evaporating the precooling refrigerant liquid stream during precooling, and heating the precooling refrigerant vapor stream during precooling. The method further includes the steps of compressing the heated main refrigerant to form a compressed main refrigerant, cooling the compressed main refrigerant to form a cooled main refrigerant, and expanding the cooled main refrigerant to form an expanded main refrigerant, which is heated during the pre-cooling and cooling steps. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a schematic diagram of an embodiment of a cryogenic gas cooling system of the present disclosure. DETAILED DESCRIPTION
[0018] According to an embodiment of the present disclosure, a cryogenic liquid refrigeration circuit provides pre-cooling of a cryogenic gas stream to reduce the energy required by the main refrigerant compressor of the main refrigeration circuit when liquefying or refrigerating the cryogenic gas stream. Although the embodiments described below mention hydrogen as the cryogenic gas to be liquefied and the refrigerant of the main refrigeration circuit, and nitrogen as the cryogenic liquid of the pre-cooling refrigeration circuit, alternative cryogenic gases, liquids, and refrigerant compositions may be used for each. By way of example only, the technology of the present disclosure may be used to liquefy helium using helium or a refrigerant mixture as the main refrigerant and using nitrogen as the pre-cooling refrigerant, as described in more detail below. In addition, the technology of the present disclosure may alternatively be used to cool a cryogenic gas stream without liquefying it.
[0019] It should be noted here that lines, conduits, ducts, channels and similar structures and the corresponding flows are sometimes indicated by the same reference numerals as shown in the Figures.
[0020] In addition, as used herein, and as known in the art, a heat exchanger is a device or a region in a device in which indirect heat exchange occurs between two or more streams at different temperatures or between a stream and an environment. In addition, all heat exchangers mentioned herein may be incorporated into one or more heat exchanger devices, or may each be a separate heat exchanger device. As used herein, unless otherwise indicated, the term "communication" ("communication", "communicating") generally refers to fluid communication. And although the two fluids in communication can exchange heat when mixed, this exchange will not be considered to be the same as the heat exchange in a heat exchanger, although this exchange may occur in a heat exchanger.
[0021] As used herein, the terms "high," "medium," "hot," "cold," etc. are relative to comparable flows, as is customary in the art.
[0022] Reference numerals introduced in the specification in conjunction with the drawings may be repeated in one or more subsequent drawings for shared elements or features without additional description in the specification, in order to provide context for other features.
[0023] In the claims, letters are used to identify claimed steps (e.g., a, b, and c). These letters are used to aid in referring to the method steps and are not intended to indicate the order in which the claimed steps should be performed, unless and only if such an order is specifically recited in the claims.
[0024] like Figure 1As shown, the gaseous hydrogen feed stream 8 enters the precooling cold box 12 and passes through the channels 13a and 13b of the precooling heat exchangers 14a and 14b, respectively, as explained in more detail below, where it is cooled. The cooled stream then passes through one or more adsorbers 16a and 16b. The adsorber is used to remove any type of impurities from the hydrogen fluid stream. The adsorber includes a specific material, wherein the impurities will be bound or adsorbed into the material. In one embodiment, the adsorber can be composed of carbon, in particular activated carbon material, but zeolites are also used.
[0025] The purified hydrogen stream leaving the adsorbers 16a and 16b then flows again through the heat exchanger 14a as a second pass, where it is further cooled to about 80°K or less (by way of example only). The cooled second pass then flows through the heat exchanger 14b. The channels 13a and 13b of the heat exchangers 14a and 14b are cooled by the streams 74, 98 and 52. The heat of vaporization of the liquid in the vessel 136 ensures maximum heat removal in the first pre-cooling cycle. The heat exchanger 14b may contain an ortho-para conversion catalyst 18 that converts ortho-hydrogen to para-hydrogen to reduce volatilization. In the case of hydrogen liquefaction, the maximum conversion of ortho-hydrogen to para-hydrogen is achieved in this first reactor section 18. The catalyst 18 may also be disposed in the heat exchanger 14a, or may be disposed separately in the heat exchanger 14a.
[0026] Merely by way of example, the pre-cooling cold box 12 may be constructed of perlite, with or without vacuum insulation. Alternatively, for example for smaller equipment sizes, the pre-cooling cold box may be integrated into the liquefier cold box.
[0027] The precooled hydrogen gas stream 22 leaves the precooling cold box 12, about 80K (for example) in the case of conventional operation where the precooling refrigerant evaporates at atmospheric pressure, and is directed to the liquefier cold box 24, where the hydrogen gas stream 22 is refrigerated as a supercritical fluid in the heat exchangers 26a-26f. By evaporating the precooling refrigerant at a pressure below atmospheric pressure, as described in more detail below about the precooling separation device 136, the temperature of the precooling hydrogen gas stream 22 can be reduced to even below 70K. A positive secondary conversion catalyst is also provided in each heat exchanger 26a-26f of the stream 22, so that the positive secondary conversion is carried out in parallel with refrigeration to minimize energy losses. Since the catalytic conversion has a lower energy density at higher temperatures, it is beneficial to immediately convert all positive hydrogen into a thermodynamic equilibrium secondary hydrogen form. After being expanded into a mixed phase stream using a Joule-Thomson (JT) valve 34, the liquid hydrogen product stream 32 leaves the system.
[0028] As mentioned previously, the number of heat exchangers shown may vary. Figure 1 Quantity shown.
[0029] The liquefier cold box 24 is insulated to minimize heat leakage according to specifications, and is preferably vacuum insulated, which may be achieved by a vacuum pump 36, by way of example only.
[0030] Cooling in the liquefier cold box 24 is provided by a main refrigerant including hydrogen in a main refrigeration circuit, generally indicated at 40. Cooling in the pre-cooling cold box 12 is provided primarily by a pre-cooling refrigerant cryogenic liquid in a pre-cooling refrigeration circuit, generally indicated at 42, with auxiliary cooling provided by the main refrigerant circuit 40. In the illustrated embodiment, by way of example only, the pre-cooling refrigerant used in the pre-cooling refrigeration circuit 42 is nitrogen, which may be liquefied, and / or a mixture of nitrogen, a hydrocarbon, or a noble gas.
[0031] In the main refrigeration loop 40, a hydrogen refrigerant stream 44 enters the pre-cooling cold box 12 and passes through heat exchangers 14a and 46, where the hydrogen refrigerant stream 44 is cooled by nitrogen (only as an example, alternative examples are given above) refrigerant streams 48 and 52, respectively. The cooled hydrogen fluid stream leaving the heat exchanger 46 then passes through the adsorber 54 and leaves the pre-cooling cold box 12 as stream 56. The continuously circulating refrigerant reduces the risk of carrying / carrying contaminants. Therefore, the system can be operated without the adsorber for a short period of time when the adsorber is regenerated.
[0032] Stream 56 enters the liquefier cold box 24 and is further cooled in heat exchanger 26a. The hydrogen refrigerant stream leaving heat exchanger 26a is split into streams 58 and 62.
[0033] Stream 62 is sent to an expansion device, such as expansion turbine 64, where it is expanded to a lower pressure and exits at a lower temperature as stream 65. Stream 65 is directed through heat exchanger 26c where it is further cooled. Stream 66 exits heat exchanger 26c and is sent to another expansion device, such as expansion turbine 68, where it is expanded to a lower pressure and exits at a lower temperature as stream 72. Although Figure 1 64 and 68 are shown, but a single turbine pass or additional turbine passes may also be used with intervening heat exchanger passes. In addition, alternative types of expansion devices, including but not limited to expansion valves, may be used in place of turbines 64 and 68. In addition, the arrangement of the expansion device may be located at different locations and temperature levels, including but not limited to just before leaving the pre-cooling cold box 12 and / or just after entering the liquefier cold box 24 on the stream 56, with the goal of minimizing temperature differences in heat exchange to minimize energy losses.
[0034] Valves 84 and / or 73 control the portion of stream 56 that is diverted to form stream 62 , and thus ultimately refrigeration stream 72 .
[0035] Stream 72 is directed through heat exchangers 26a-26d of the liquefier cold box to provide refrigeration therein. Heated hydrogen stream 74 then enters precooling cold box 12 to provide partial refrigeration within precooling heat exchanger 14a. Resulting hydrogen stream 76 leaves precooling cold box 12.
[0036] Hydrogen refrigerant stream 58 flows through heat exchangers 26a-26e where it is further cooled. The resulting stream 78 is fed to an optional expansion turbine 80 (or other expansion device) where it is expanded to a lower pressure and exits at a lower temperature as stream 82. Stream 82 may be (further) expanded by an expansion device such as a Joule-Thomson valve 84, and the resulting mixed phase stream 86 is directed to a main refrigerant separation device 88.
[0037] Liquid hydrogen refrigerant stream 92 leaves the bottom of main refrigerant separation device 88 and is directed through liquefier evaporator 26f of liquefier cold box to provide refrigeration therein. The heat of evaporation is used for the final cooling step and positive secondary conversion of hydrogen feed gas stream. JT expansion valve 34 may also or alternatively be located between 26e and 26f heat exchangers. It may also be implemented as an ejector.
[0038] Hydrogen refrigerant vapor stream 94 exits the top of main refrigerant separation device 88 and combines with stream 92 to form combined hydrogen refrigerant stream 96 which is directed through liquefier heat exchangers 26e-26a to provide refrigeration therein. Resulting heated hydrogen refrigerant stream 98 exits liquefier cold box 24.
[0039] Streams 72 and 96 cooperate to provide the refrigeration required to liquefy the pre-cooled hydrogen stream 22 in the liquefier cold box 24. For example, the temperature of the hydrogen stream 22 may be reduced at the cold end of the liquefier cold box 24 to about 20°K-22°K.
[0040] Stream 98 flows into pre-cooling box 12 to provide partial refrigeration in heat exchanger 14a. Resulting hydrogen stream 102 leaves pre-cooling box 12.
[0041] The hydrogen refrigerant vapor stream 102 travels to the first main compressor 104 of the main refrigeration circuit and is pressurized to form an intermediate-pressure vapor stream 106. The hydrogen refrigerant vapor stream 76 is combined with the intermediate-pressure vapor stream 106 to form a combined hydrogen refrigerant vapor stream 108, which is pressurized in the second main compressor 112 to form a high-pressure vapor stream 114. Stream 102 requires additional compression / pressurization provided by compressor 104 to compensate for the additional pressure drop experienced by stream 58 when passing through the additional heat exchangers of the liquefier cold box 24, the turbine 80, the JT valve 84, and the separation device 88.
[0042] In some embodiments, the pressure in vessel 88 may be minimized to have the lowest possible evaporation temperature. To this end, in such embodiments, by way of example only, a small portion of stream 82 boils in the 20K range, providing a heat sink for a liquefier operating at 1.3-1.5 bar.
[0043] The high pressure vapor stream 114 is directed through a primary cooling device, such as a heat exchanger 116, where it is cooled by direct / indirect heat exchange with a water stream 118 and / or an air cooler where sufficient cooling water is lacking. As a result, a hydrogen refrigerant stream 44 is formed. Alternative cooling fluids including, but not limited to, ambient air, may be used in place of water 118.
[0044] In the pre-cooling refrigeration loop 42, nitrogen refrigerant vapor 122 enters a pre-cooling compressor 124. The resulting compressed stream is cooled in a pre-cooling cooling device such as a heat exchanger 126 by indirect heat exchange with a water stream 128. Alternative cooling fluids, including but not limited to ambient air, may be used in place of the water stream 128. The resulting cooled nitrogen vapor stream is expanded in a pre-cooling expansion device (e.g., an expansion turbine 132 and / or a combination of an expansion turbine and a compressor). The resulting mixed-phase nitrogen stream 134 is directed to a pre-cooling refrigeration loop separation device 136.
[0045] Different arrangements of compressor / heat exchangers known in the air separation industry are contemplated in the precooling section, including but not limited to compressed nitrogen expanded in a JT valve into vessel 136, where only a portion of stream 134 enters. The remainder of the stream may be passed through heat exchanger 52 via an expansion turbine / compressor.
[0046] The pre-cooling refrigeration circuit separation device 136 is preferably operated at reduced pressure to reduce the boiling temperature of the incoming pre-cooling refrigerant stream 134. By way of example only, when nitrogen is used as the pre-cooling liquid refrigerant, the pressure within the separation device 136 may be 0.5 bar in order to reduce the boiling temperature of the nitrogen in the separation device from 78 K to 73 K. In fact, as an alternative to nitrogen, any pre-cooling refrigerant that allows operation at a temperature below 77 K will improve the overall process efficiency.
[0047] Liquid nitrogen refrigerant stream 52 exits the pre-cooling refrigeration circuit separation device 136 and, as previously described, provides cooling in heat exchanger 46. Overhead vapor stream 138 exits separation device 136 and joins with the nitrogen stream exiting heat exchanger 46. The resulting combined nitrogen refrigerant stream 48 flows through heat exchanger 14a and provides refrigeration therein, thereby producing nitrogen refrigerant vapor stream 122. In an alternative embodiment, separation device 136 may be omitted so that streams 52 and 48 are formed directly from stream 134.
[0048] Figure 1The compressors 104 and 112 of the main refrigeration circuit 40 require more energy to operate than the compressor 124 of the pre-cooling refrigeration circuit 42. In addition, the pre-cooling refrigeration circuit 42 reduces the cooling requirements of the main refrigeration circuit 40, thereby reducing the compression requirements. As a result, Figure 1 The embodiments effectively allow a portion of the system's cooling power to be transferred from the main refrigeration loop 40 to the pre-cooling refrigeration loop 42, thereby reducing the system's overall energy usage and power requirements, and therefore reducing the liquefaction of the hydrogen feed stream (the Carnot cycle process at high temperature requires less energy).
[0049] In an alternative embodiment of the system of the present disclosure, Figure 1 The system can be reconfigured to liquefy helium by removing heat exchangers 26e and 26f and adding an expansion device (e.g., a JT valve) downstream of heat exchanger 26d. As a result, in such a system, stream 58 will be expanded in the JT valve after passing through heat exchangers 26a-26d. By way of example only, in such a system, helium can be the refrigerant for the main refrigeration circuit and nitrogen can be the cryogenic liquid for the pre-cooling refrigeration circuit.
[0050] While preferred embodiments of the present disclosure have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made thereto without departing from the spirit of the present disclosure, the scope of which is defined by the appended claims.
Claims
1. A system for liquefying a cryogenic gas feed stream, comprising: a. A precooling heat exchanger comprising a precooling refrigerant heating channel, a main refrigerant cooling channel, a main refrigerant heating channel and a feed gas cooling channel; b. Pre-cooling refrigeration circuit, including: i) a precooling compressor configured to receive and compress precooling refrigerant vapor from a precooling refrigerant heating passage of a precooling heat exchanger; ii) a pre-cooling cooling device configured to receive and cool compressed pre-cooling refrigerant from a pre-cooling compressor; iii) a pre-cooling expansion device configured to receive and expand compressed and cooled pre-cooling refrigerant from the pre-cooling cooling device; iv) a precooling separation device configured to receive the expanded precooling refrigerant from the precooling expansion device under reduced pressure so as to reduce the boiling point of the expanded precooling refrigerant and to separate the expanded precooling refrigerant into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream, the precooling separation device having a vapor outlet and a liquid outlet in fluid communication with the precooling refrigerant heating passage of the precooling heat exchanger; c. A liquefier heat exchanger comprising a main refrigerant cooling channel, a main refrigerant heating channel and a feed gas cooling channel; d. Main refrigeration circuit, including: i) a first main compressor configured to receive and compress main refrigerant vapor from a main refrigerant heating path of the liquefier heat exchanger and the pre-cooling heat exchanger; ii) a main cooling device configured to receive and cool compressed main refrigerant from the first main compressor, the main cooling device having an outlet in fluid communication with the main refrigerant cooling passages of the pre-cooling heat exchanger and the liquefier heat exchanger; iii) a first main expansion device configured to receive and expand compressed and cooled main refrigerant from a main refrigerant cooling passage of the liquefier heat exchanger, the first main expansion device having an outlet in fluid communication with the main refrigerant heating passage of the liquefier heat exchanger and the pre-cooling heat exchanger; e. the precooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel of the precooling heat exchanger and the low-temperature gas in the feed gas cooling channel are cooled by the precooling refrigerant in the precooling refrigerant heating channel and the main refrigerant in the main refrigerant heating channel; and f. The liquefier heat exchanger is configured so that the main refrigerant in the main refrigerant cooling passage is cooled, and the low temperature fluid in the feed gas cooling passage is liquefied by the main refrigerant in the main refrigerant heating passage.
2. The system of claim 1 further comprising a precooling cold box in which the precooling heat exchanger is located and a liquefier cold box in which the liquefier heat exchanger is located.
3. The system according to claim 2, wherein: The liquefier heat exchanger is vacuum insulated.
4. The system according to claim 1, wherein: The first main expansion device is a Joule-Thomson valve.
5. The system according to claim 1, wherein: The liquefaction heat exchanger includes a first liquefaction heat exchanger having a first main refrigerant cooling channel, a first main refrigerant heating channel, and a second main refrigerant heating channel, the liquefaction heat exchanger also includes a second liquefaction heat exchanger having a second main refrigerant cooling channel, a third main refrigerant cooling channel, a third main refrigerant heating channel, and a fourth main refrigerant heating channel, and further includes: g. a flow divider configured to receive the main refrigerant leaving the first main refrigerant channel cooling channel; h. a second main expansion device configured to receive a first portion of the main refrigerant from the splitter, the second main expansion device having a second main expansion device outlet; i. The second main refrigerant cooling passage of the second heat exchanger is configured to receive and cool a first portion of the main refrigerant from an outlet of the second main expansion device, the second main refrigerant cooling passage being in fluid communication with the third and first main refrigerant heating passages; j. The third main refrigerant cooling passage of the second heat exchanger is configured to receive and cool the second portion of the main refrigerant from the flow divider, and the third main refrigerant cooling passage is in fluid communication with the fourth and second main refrigerant heating passages.
6. The system according to claim 5, wherein: The second main expansion device is a turbine.
7. The system of claim 5, further comprising a third main expansion device configured to receive the first portion of main refrigerant from the second main refrigerant cooling passage of the second liquefaction heat exchanger, the third main expansion device having a third main expansion device outlet, wherein The third and first main refrigeration passages are configured to receive a first portion of the main refrigerant from a third main expansion device outlet.
8. The system according to claim 7, wherein: The second and third expansion devices are turbines.
9. The system according to claim 5, wherein: The first main compressor has a first main compressor inlet, which is configured to receive a second portion of the main refrigerant from the second main refrigerant heating channel of the first heat exchanger, and also includes a second main compressor having a main compressor inlet, which is configured to receive the main refrigerant from the first main refrigerant heating channel and the main refrigerant from the first main compressor.
10. The system according to claim 1, wherein: The cryogenic gas feed stream comprises hydrogen, the main refrigerant comprises hydrogen, and the pre-cooling refrigerant comprises nitrogen.
11. The system according to claim 1, wherein: The pre-cooling refrigerant is nitrogen, and the pressure in the pre-cooling separation device is reduced to about 0.5 bar to reduce the boiling temperature of nitrogen from 78K to about 73K.
12. The system of claim 1, wherein: The pressure in the precooling separation device is reduced to a level at which the boiling temperature of the precooling refrigerant is lower than 77K.
13. A method for liquefying a cryogenic gas feed stream comprising the steps of: a. precooling the cryogenic gas feed stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream; b. liquefying the pre-cooled cryogenic fluid stream using the main refrigerant; c. wherein step a forms a heated pre-cooling refrigerant, and steps a and b form a heated main refrigerant; d. compressing the heated precooling refrigerant to form a compressed precooling refrigerant; e. cooling the compressed pre-cooling refrigerant to form a cooled pre-cooling refrigerant; f. expanding the cooled precooling refrigerant to form an expanded precooling refrigerant; g. reducing the pressure of the expanded pre-cooling refrigerant, thereby reducing the boiling point of the pre-cooling refrigerant; h. The precooling refrigerant in step g is separated into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream; i. evaporating the precooling refrigerant liquid stream during the precooling step a; j. heating the precooling refrigerant vapor stream during the precooling of step a; k. compressing the heated main refrigerant to form a compressed main refrigerant; l. Cooling the compressed main refrigerant to form a cooled main refrigerant; m. Expanding the cooled main refrigerant to form an expanded main refrigerant which was heated during the pre-cooling in step a and the liquefaction in step b.
14. The method according to claim 13, wherein: The cryogenic gas feed stream comprises hydrogen, the pre-cooling refrigerant comprises nitrogen, and the main refrigerant comprises hydrogen.
15. The method according to claim 13, wherein: The cooling in steps e and h is carried out using water.
16. The method according to claim 13, wherein: The cooling of step h includes cooling by the pre-cooling refrigerant.
17. The method according to claim 13, wherein: The precooling refrigerant is nitrogen, and in step g, the pressure in the precooling separation device is reduced to about 0.5 bar to reduce the boiling temperature of nitrogen from 78K to about 73K.
18. The method according to claim 13, wherein: In step g, the pressure in the precooling separation device is reduced to a level at which the boiling temperature of the precooling refrigerant is lower than 77K.
19. A system for cooling a cryogenic gas feed stream, comprising: a. A precooling heat exchanger comprising a precooling refrigerant heating channel, a main refrigerant cooling channel, a main refrigerant heating channel and a feed gas cooling channel; b. Pre-cooling refrigeration circuit, including: i) a precooling compressor configured to receive and compress precooling refrigerant vapor from a precooling refrigerant heating passage of a precooling heat exchanger; ii) a pre-cooling cooling device configured to receive and cool compressed pre-cooling refrigerant from a pre-cooling compressor; iii) a pre-cooling expansion device configured to receive and expand compressed and cooled pre-cooling refrigerant from the pre-cooling cooling device; iv) a precooling separation device configured to receive the expanded precooling refrigerant from the precooling expansion device under reduced pressure so as to reduce the boiling point of the expanded precooling refrigerant and to separate the expanded precooling refrigerant into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream, the precooling separation device having a vapor outlet and a liquid outlet in fluid communication with the precooling refrigerant heating passage of the precooling heat exchanger; c. A cooling heat exchanger comprising a main refrigerant cooling channel, a main refrigerant heating channel and a feed gas cooling channel; d. Main refrigeration circuit, including: i) a first main compressor configured to receive and compress main refrigerant vapor from the main refrigerant heating passage of the cooling heat exchanger and the pre-cooling heat exchanger; ii) a main cooling device configured to receive and cool compressed main refrigerant from the first main compressor, the main cooling device having an outlet in fluid communication with the main refrigerant cooling passages of the pre-cooling heat exchanger and the cooling heat exchanger; iii) a first main expansion device configured to receive and expand compressed and cooled main refrigerant from a main refrigerant cooling passage of the cooling heat exchanger, the first main expansion device having an outlet in fluid communication with the main refrigerant heating passages of the cooling heat exchanger and the pre-cooling heat exchanger; e. the precooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling channel of the precooling heat exchanger and the low-temperature gas in the feed gas cooling channel are cooled by the precooling refrigerant in the precooling refrigerant heating channel and the main refrigerant in the main refrigerant heating channel; and f. The cooling heat exchanger is configured so that the main refrigerant in the main refrigerant cooling passage is cooled, and the low-temperature fluid in the feed gas cooling passage is cooled by the main refrigerant in the main refrigerant heating passage.
20. A method for cooling a cryogenic gas feed stream comprising the steps of: a. precooling the cryogenic gas feed stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream; b. cooling the pre-cooled cryogenic fluid stream using a primary refrigerant; c. wherein step a forms a heated pre-cooling refrigerant, and steps a and b form a heated main refrigerant; d. compressing the heated precooling refrigerant to form a compressed precooling refrigerant; e. cooling the compressed pre-cooling refrigerant to form a cooled pre-cooling refrigerant; f. expanding the cooled precooling refrigerant to form an expanded precooling refrigerant; g. reducing the pressure of the expanded precooling refrigerant, thereby reducing the boiling point of the precooling refrigerant; h. The precooling refrigerant in step g is separated into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream; i. evaporating the precooling refrigerant liquid stream during the precooling step a; j. heating the precooling refrigerant vapor stream during the precooling of step a; k. compressing the heated main refrigerant to form a compressed main refrigerant; l. Cooling the compressed main refrigerant to form a cooled main refrigerant; m. Expanding the cooled main refrigerant to form an expanded main refrigerant which was heated during the pre-cooling of step a and the cooling of step b.