Ultra-low temperature gas cooling system and method

Abstract

The precooling refrigeration circuit includes a precooling compressor configured to receive and compress precooling refrigerant vapor from a precooling heat exchanger, a precooling cooling device configured to receive and cool the precooling refrigerant compressed by the precooling compressor, a precooling expansion device configured to receive and expand the precooling refrigerant compressed and cooled by the precooling cooling device, and a precooling separation device configured to receive the expanded precooling refrigerant from the precooling expansion device at a low pressure, lower 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 main refrigeration circuit includes a first main compressor configured to receive and compress main refrigerant vapor from a liquefier heat exchanger and a precooling heat exchanger, and a main cooling device configured to receive and cool the main refrigerant compressed by the first main compressor. The main cooling device is in fluid communication with the precooling heat exchanger and the liquefier exchanger.

Description

Technical Field

[0001] Claims of Priority

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 349,354, filed Jun. 6, 2022, the contents of which are incorporated herein by reference.

[0002]

[0002] The present disclosure generally relates to systems and methods for refrigeration using cryogenic gases or for liquefying cryogenic gases, and more particularly, to systems and methods for cooling cryogenic gases including a cryogenic liquid precooling loop.

Background Art

[0003]

[0003] Industrial cryogenic gases such as natural gas, hydrogen, neon, or helium are advantageously stored or transported in a liquid state because they occupy a much smaller volume in the liquid state (e.g., natural gas is 1 / 600 of its gaseous state). The liquefied gas is then vaporized back to a gaseous state for use on-site or in a system. The same cryogenic gases are also used in refrigerators, typically for research in particle accelerators, simulation of cosmic temperatures, analysis of decelerated particles (cold neutron sources), and other scientific applications. However, such refrigerators typically warm liquid nitrogen to provide refrigeration and then release the vaporized nitrogen into the atmosphere, thus consuming nitrogen.

[0004]

[0004] The liquefaction of cryogenic gases is often costly. For example, gaseous hydrogen is converted to liquid hydrogen by cooling it to about -253°C. As a result, typical cooling processes use large amounts of energy. Further, this process may include multiple refrigeration cycles and may involve multiple gas compression stages.

[0005]

[0005] A hydrogen liquefaction system typically includes a hydrogen refrigerant cycle using a compressor. Hydrogen is difficult to compress due to its low molecular weight and low viscosity. As a result, such a compressor typically consumes most of the energy required to operate the system. Similarly, helium is also quite costly to compress. Improving energy efficiency is desirable for cryogenic gas liquefaction systems and methods.

Summary of the Invention

Means for Solving the Problems

[0006]

[0006] Some aspects of the present subject matter can be embodied separately or together in the methods, apparatuses, 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 describing these aspects together is not intended to exclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto.

[0007]

[0007] In one aspect, a system for liquefying a cryogenic gas supply stream includes a precooling heat exchanger including a precoolant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a supply gas cooling passage. The precooling refrigeration circuit includes a precooling compressor configured to receive and compress precoolant vapor from the precoolant heating passage of the precooling heat exchanger, a precooling cooling device configured to receive and cool the compressed precoolant from the precooling compressor, a precooling expansion device configured to receive and expand the compressed and cooled precoolant from the precooling cooling device, and a precooling separation device configured to receive the expanded precoolant from the precooling expansion device at a low pressure, lower the boiling point of the expanded precoolant, and separate the expanded precoolant into a precoolant vapor stream and a precoolant liquid stream. The precooling separation device has a vapor outlet and a liquid outlet in fluid communication with the precoolant heating passage of the precooling heat exchanger.

[0008]

[0008] The liquefier heat exchanger includes a main refrigerant cooling passage, a main refrigerant heating passage, and a supply 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 passages of the liquefier heat exchanger and the precooling heat exchanger. The main cooling device is configured to receive and cool the main refrigerant compressed by the first main compressor, and the main cooling device has an outlet in fluid communication with the main refrigerant cooling passages 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, and the first main expansion device has an outlet in fluid communication with the main refrigerant heating passages of the liquefier heat exchanger and the precooling heat exchanger.

[0009]

[0009] The precooling heat exchanger is configured such that the main refrigerant in the main refrigerant cooling passage of the precooling heat exchanger and the cryogenic gas in the supply gas cooling passage are cooled by the precooling refrigerant in the precooling refrigerant heating passage and the main refrigerant in the main refrigerant heating passage. The liquefier heat exchanger is configured such that the main refrigerant in the main refrigerant cooling passage is cooled and the cryogenic fluid in the supply gas cooling passage is liquefied by the main refrigerant in the main refrigerant heating passage.

[0010]

[0010] In another aspect, a method for liquefying an ultra-cold gas supply stream includes pre-cooling the ultra-cold gas supply stream using a pre-cooling refrigerant and a main refrigerant to form a pre-cooled ultra-cold fluid stream, and liquefying the pre-cooled ultra-cold fluid stream using the main refrigerant. The warmed pre-cooling refrigerant is formed by the pre-cooling step, and the pre-cooling and liquefying steps form the warmed main refrigerant. The method further includes compressing the warmed pre-cooling refrigerant to form a compressed pre-cooling refrigerant, cooling the compressed pre-cooling refrigerant to form a cooled pre-cooling refrigerant, expanding the cooled pre-cooling refrigerant to form an expanded pre-cooling refrigerant, reducing the pressure of the expanded pre-cooling refrigerant to lower the boiling point of the pre-cooling refrigerant, separating the pre-cooling refrigerant into a pre-cooling refrigerant vapor stream and a pre-cooling refrigerant liquid stream, vaporizing the pre-cooling refrigerant liquid stream during pre-cooling, and warming the pre-cooling refrigerant vapor stream during pre-cooling. The method further includes compressing the warmed 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 that is warmed during the pre-cooling and liquefying steps.

[0011]

[0011] The method further includes using the liquefied gas supplied to the phase separator 136 as the pre-cooling refrigerant, and this liquefied gas is evaporated in the shown heat exchanger 46. In the case of liquid nitrogen, it is typically exhausted to the atmosphere, but a vacuum pump (or ejector) 124 is required to reduce the pressure.

[0012]

[0012] In another aspect, a system for cooling an ultra-low temperature gas supply stream includes a precooling heat exchanger that includes a precooling refrigerant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a supply 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 precooling refrigerant compressed by the precooling compressor, a precooling expansion device configured to receive and expand the precooling refrigerant compressed and cooled by the precooling cooling device, and a precooling separation device configured to receive the expanded precooling refrigerant at a low pressure from the precooling expansion device, lower the boiling point of the expanded precooling refrigerant, and separate the expanded precooling refrigerant into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream. The precooling separation device has a vapor outlet and a liquid outlet that are in fluid communication with the precooling refrigerant heating passage of the precooling heat exchanger.

[0013]

[0013] The cooling heat exchanger includes a main refrigerant cooling passage, a main refrigerant heating passage, and a supply 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 passages of the cooling heat exchanger and the precooling heat exchanger. The main cooling device is configured to receive and cool the main refrigerant compressed by the first main compressor, and the main cooling device has an outlet that is in fluid communication with the main refrigerant cooling passages of the precooling heat exchanger and the cooling exchanger. The first main expansion device is configured to receive and expand the main refrigerant compressed and cooled from the main refrigerant cooling passage of the cooling heat exchanger, and the first main expansion device has an outlet that is in fluid communication with the main refrigerant heating passages of the cooling heat exchanger and the precooling heat exchanger.

[0014]

[0014] The precooling heat exchanger is configured such that the main refrigerant in the main refrigerant cooling passage of the precooling heat exchanger and the ultra-low temperature gas in the supply gas cooling passage are cooled by the precooling refrigerant in the precooling refrigerant heating passage and the main refrigerant in the main refrigerant heating passage. The cooling heat exchanger is configured such that the main refrigerant in the main refrigerant cooling passage is cooled and the ultra-low temperature fluid in the supply gas cooling passage is cooled by the main refrigerant in the main refrigerant heating passage.

[0015]

[0015] In another aspect, a method for cooling a cryogenic gas supply stream includes pre-cooling the cryogenic gas supply stream using a pre-cooling refrigerant and a main refrigerant to form a pre-cooled cryogenic fluid stream, and cooling the pre-cooled cryogenic fluid stream using the main refrigerant. A warmed pre-cooling refrigerant is formed by the pre-cooling step, and the pre-cooling and liquefaction steps form a warmed main refrigerant. The method further includes compressing the warmed pre-cooling refrigerant to form a compressed pre-cooling refrigerant, cooling the compressed pre-cooling refrigerant to form a cooled pre-cooling refrigerant, expanding the cooled pre-cooling refrigerant to form an expanded pre-cooling refrigerant, reducing the pressure of the expanded pre-cooling refrigerant to lower the boiling point of the pre-cooling refrigerant, separating the pre-cooling refrigerant into a pre-cooling refrigerant vapor stream and a pre-cooling refrigerant liquid stream, vaporizing the pre-cooling refrigerant liquid stream during pre-cooling, and warming the pre-cooling refrigerant vapor stream during pre-cooling. The method further includes compressing the warmed 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 that is warmed during the pre-cooling and cooling steps.

Brief Description of the Drawings

[0016]

Figure 1

[0016] It is a schematic diagram of an embodiment of the cryogenic gas cooling system of the present disclosure.

Modes for Carrying Out the Invention

[0017]

[0017] According to an embodiment of the present disclosure, the cryogenic liquid refrigeration circuit pre-cools the cryogenic gas stream to reduce the energy required by the main refrigerant compressor of the main refrigeration circuit when liquefying or freezing the cryogenic gas stream. In the embodiments described below, both the cryogenic gas to be liquefied and the refrigerant of the main refrigeration circuit refer to hydrogen, and the cryogenic liquid of the pre-cooling refrigeration circuit refers to nitrogen, but alternative cryogenic gases, liquids, and refrigerant compositions may be used for each. As a mere example, the technology of the present disclosure may be used to liquefy helium using helium or a mixture of refrigerants as the main refrigerant and nitrogen as the pre-cooling refrigerant, as described in more detail below. Further, the technology of the present disclosure may instead be used to cool the cryogenic gas stream without liquefying it.

[0018]

[0018] It should be noted that in this specification, lines, conduits, pipes, passages, and similar structures, as well as the corresponding flows, may both be referred to by the same element numbers shown in the figures.

[0019]

[0019] Also, as used in this specification, as is known in the art, a heat exchanger is a device or a region within a device in which indirect heat exchange occurs between two or more flows at different temperatures, or between a flow and the surroundings. In addition, all heat exchangers referred to in this specification may be incorporated into one or more heat exchanger devices, or each may be an individual heat exchanger device. As used in this specification, terms such as "communicate" and "communicating" generally refer to fluid communication unless otherwise specified. Also, two fluids that communicate may exchange heat when mixed, and such exchange may occur within a heat exchanger, but it is not considered the same as the heat exchange within the heat exchanger.

[0020]

[0020] As used in this specification, terms such as "high", "intermediate", "warm", and "cold" are relative to comparable flows as is customary in the art.

[0021]

[0021] Reference numerals introduced in the specification in connection with the drawings may be repeated for elements or components that are shared without further explanation in the specification in one or more subsequent figures to describe other features.

[0022]

[0022] In the claims, letters are used to identify the claimed steps (e.g., a, b, and c). These letters are used for convenience in referring to method steps and are not intended to indicate the order in which such steps are to be performed, unless and only to the extent that the order in which the claimed steps are to be performed is specifically recited in the claims.

[0023]

[0023] As shown in FIG. 1, a gaseous hydrogen feed stream 8 enters a pre-cooling cold box 12 and passes through passages 13a and 13b of pre-cooling heat exchangers 14a and 14b, respectively, in which it is cooled, as will be described in more detail below. The cooled stream then passes through one or more adsorbers 16a and 16b. The adsorbers function to remove any type of impurity from the hydrogen fluid stream. The adsorbers contain a specific material to which the impurities bind or are absorbed. In one embodiment, the adsorbers can be composed of carbon, specifically an activated carbon material, although zeolites are also used.

[0024]

[0024] The purified hydrogen gas stream exiting the suction devices 16a and 16b then again passes through the heat exchanger 14a as the second flow path, where it is further cooled (as an example only) to approximately 80°K or less. The cooled flow of the second flow path then flows through the heat exchanger 14b. The passages 13a and 13b of the heat exchangers 14a and 14b are cooled by the flows 74, 98, and 52. The latent heat of vaporization of the liquid within the container 136 ensures the maximum heat removal in the first precooling cycle. The heat exchanger 14b can include an ortho-para conversion catalyst 18 for converting ortho hydrogen to para hydrogen to reduce volatilization. In the case of hydrogen liquefaction, the maximum conversion from ortho hydrogen to para hydrogen is achieved in this first reactor segment 18. The catalyst 18 may also be provided in the heat exchanger 14a, or alternatively, only in the heat exchanger 14a.

[0025]

[0025] As an example, the precooling cold box 12 can be constructed of perlite, regardless of the presence or absence of vacuum insulation. Alternatively, for example, in the case of a smaller plant size, the precooling cold box may be incorporated into the liquefier cold box.

[0026]

[0026] In the case of a conventional operation where the precooled hydrogen gas stream 22 evaporates the precooling refrigerant at atmospheric pressure, it exits the precooling cold box 12 at approximately 80K (for example) and is directed to the liquefier cold box 24, where it is frozen as a supercritical fluid in the heat exchangers 26a - 26f. As will be described in more detail below with respect to the precooling separation device 136, by evaporating the precooling refrigerant at a pressure lower than atmospheric pressure, the temperature of the precooled hydrogen gas stream 22 can be lowered even below 70K. The ortho-para conversion catalyst is also provided in each of the heat exchangers 26a - 26f of the flow 22 such that the ortho-para conversion occurs in parallel with the refrigeration to minimize exergy loss. This catalytic conversion is beneficial as the energy consumption decreases with increasing temperature, so it is beneficial to immediately convert all ortho hydrogen into the thermodynamically equilibrium form of para hydrogen. The liquid hydrogen product stream 32 is expanded using a Joule-Thompson (JT) valve 34 to a mixed-phase flow and then exits the system.

[0027]

[0027] As shown above, the number of heat exchangers shown may be changed from that shown in FIG. 1.

[0028]

[0028] The liquefier cold box 24 is insulated to minimize heat leakage according to technical requirements and is preferably vacuum-insulated, which may be achieved, by way of example only, by a vacuum pump 36.

[0029]

[0029] Cooling is provided within the liquefier cold box 24 by a main refrigerant containing hydrogen within the main refrigeration circuit generally designated 40. Cooling is mainly provided within the precooling cold box 12 by a precooling refrigerant cryogenic liquid within the precooling refrigeration circuit generally designated 42, with supplementary cooling being provided by the main refrigerant circuit 40. In the illustrated embodiment, by way of example only, the precooling refrigerant used in the precooling refrigeration circuit 42 is nitrogen, optionally liquid nitrogen, and / or a mixture of nitrogen, hydrocarbons, or noble gases.

[0030]

[0030] In the main refrigeration circuit 40, the hydrogen refrigerant stream 44 enters the precooling cold box 12 and passes through heat exchangers 14a and 46, where it is cooled by, by way of example only, nitrogen (alternative examples are presented above) refrigerant streams 48 and 52 respectively. The cooled hydrogen fluid stream exiting heat exchanger 46 then passes through adsorber 54 and exits the precooling cold box 12 as stream 56. The continuously circulating refrigerant has a low risk of carrying / picking up contaminants. For this reason, it is possible to operate the system without an adsorber for a short period to regenerate the adsorber.

[0031]

[0031] Stream 56 enters the liquefier cold box 24 and is further cooled in heat exchanger 26a. The hydrogen refrigerant stream exiting heat exchanger 26a is split into stream 58 and stream 62.

[0032]

[0032] The flow 62 is sent to an expansion device such as an expansion turbine 64, where it expands to a lower pressure and exits as flow 65 at a lower temperature. The flow 65 is directed to pass through the heat exchanger 26c, where it is further cooled. The flow 66 exits the heat exchanger 26c and is sent to a further expansion device such as an expansion turbine 68, where it expands to a lower pressure and exits as flow 72 at a lower temperature. Although expansion turbines 64 and 68 are shown in FIG. 1, instead, a single turbine flow path with heat exchanger flow paths or additional turbine flow paths may be used. Additionally, instead of turbines 64 and 68, alternative types of expansion devices including, but not limited to, expansion valves may be used. Further, the arrangement of the expansion devices may be at different positions and temperature levels including, but not limited to, immediately before exiting the precooling cold box 12 and / or immediately after entering the liquefier cold box 24 for the purpose of minimizing the temperature difference for heat exchange to minimize exergy loss.

[0033]

[0033] The valves 84 and / or 73 control the portion of the flow 56 that is diverted to form the flow 62 and thus ultimately the refrigeration flow 72.

[0034]

[0034] The flow 72 is directed to pass through the heat exchangers 26a - 26d of the liquefier cold box, where it provides refrigeration. Then, the heated hydrogen flow 74 proceeds into the precooling cold box 12 and provides a portion of the refrigeration in the precooling heat exchanger 14a. The resulting hydrogen gas flow 76 exits the precooling cold box 12.

[0035]

[0035] The hydrogen refrigerant flow 58 moves through the heat exchangers 26a - 26e, where it is further cooled. The resulting flow 78 is sent to an optional expansion turbine 80 (or other expansion device), where it expands to a lower pressure and exits as flow 82 at a lower temperature. The flow 82 can be (further) expanded by an expansion device such as a Joule - Thomson valve 84, and the resulting mixed - phase flow 86 is directed to the main refrigerant separator 88.

[0036]

[0036] The liquid hydrogen refrigerant stream 92 exits from the bottom of the main refrigerant separator 88 and is guided to pass through the liquefier evaporator 26f of the liquefier cold box, where it provides refrigeration. The latent heat of vaporization is used for the final cooling step of the hydrogen supply gas stream and the ortho-para conversion. The JT expansion valve 34 can also be arranged between the heat exchangers 26e and 26f or alternatively in place of this. Also, the JT expansion valve 34 may be implemented as an ejector.

[0037]

[0037] The hydrogen refrigerant vapor stream 94 exits from the top of the main refrigerant separator 88 and is combined with the stream 92 to form a combined hydrogen refrigerant stream 96, which is guided to pass through the liquefier heat exchangers 26e - 26a, where it provides refrigeration. The resulting warmed hydrogen refrigerant stream 98 exits the liquefier cold box 24.

[0038]

[0038] The streams 72 and 96 cooperate to provide the refrigeration necessary to liquefy the hydrogen stream 22 pre-cooled within the liquefier cold box 24. For example, the temperature of the hydrogen gas stream 22 can be reduced to about 20°K - 22°K at the low-temperature end of the liquefier cold box 24.

[0039]

[0039] The stream 98 flows into the pre-cooling cold box 12 and provides part of the refrigeration within the heat exchanger 14a. The resulting hydrogen gas stream 102 exits the pre-cooling cold box 12.

[0040]

[0040] The hydrogen refrigerant vapor stream 102 moves 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 merges with the intermediate-pressure vapor stream 106 to form a combined hydrogen refrigerant vapor stream 108, which is pressurized by the second main compressor 112 to form a high-pressure vapor stream 114. In order to compensate for the additional pressure drop that the stream 58 experiences when passing through the additional heat exchangers, turbine 80, JT valve 84, and separator 88 of the liquefier cold box 24, the stream 102 requires additional compression / pressurization provided by the compressor 104.

[0041]

[0041] In some embodiments, the pressure in the container 88 may be minimized in order to make the evaporation temperature as low as possible. For this reason, in such embodiments, by way of example only, a small partial flow 82 boils in the range of 20K, which provides a heat absorption source to a liquefier operating at 0.13 to 0.15 MPa (absolute pressure) (1.3 to 1.5 bar (absolute pressure)).

[0042]

[0042] The high-pressure steam flow 114 is directed to pass through a main cooling device such as the heat exchanger 116, where it is cooled by the water flow 118 and / or direct / indirect heat exchange with an air cooler where there is no sufficient cooling water. As a result, a hydrogen refrigerant flow 44 is formed. Instead of water 118, an alternative cooling fluid including, but not limited to, ambient air may be used.

[0043]

[0043] In the precooling refrigeration circuit 42, the nitrogen refrigerant vapor 122 enters the precooling compressor 124. The resulting compressed flow is cooled by indirect heat exchange with the water flow 128 in a precooling cooling device such as the heat exchanger 126. Instead of the water flow 128, an alternative cooling fluid including, but not limited to, ambient air may be used. The resulting cooled nitrogen vapor flow is expanded in a precooling expansion device such as an expansion turbine 132 and / or a combination of an expansion turbine and a compressor. The resulting mixed-phase nitrogen flow 134 is directed to the precooling refrigeration circuit separator 136.

[0044]

[0044] In the precooling section, different configurations for compressors / heat exchangers are foreseen as known in the air separation industry, including, but not limited to, expanding compressed nitrogen into the container 136 with a JT valve (only a part of the flow 134 enters). The remaining flow can pass through the heat exchanger 52 via an expansion turbine / compressor.

[0045]

[0045] The precooling refrigeration circuit separator 136 is preferably operated at a low pressure to lower the boiling temperature of the incoming precooling refrigerant stream 134. As a mere example, if nitrogen is used as the precooling liquid refrigerant, the pressure within the separator 136 may be 0.05 MPa (0.5 bar) so as to lower the boiling temperature of the nitrogen within the separator from 78 K to 73 K. In fact, as an alternative to nitrogen, any precooling refrigerant that can operate at a temperature lower than 77 K improves the overall process efficiency.

[0046]

[0046] The liquid nitrogen refrigerant stream 52 exits the precooling refrigeration circuit separator 136 and, as described above, provides cooling in the heat exchanger 46. The overhead vapor stream 138 exits the separator 136 and merges with the nitrogen stream exiting the heat exchanger 46. The resulting combined nitrogen refrigerant stream 48 flows through the heat exchanger 14a where it provides refrigeration, resulting in the production of a nitrogen refrigerant vapor stream 122. In an alternative embodiment, the separator 136 may be omitted, such that streams 52 and 48 are formed directly from stream 134.

[0047]

[0047] The compressors 104 and 112 of the main refrigeration circuit 40 of FIG. 1 require more energy to operate than the compressor 124 of the precooling refrigeration circuit 42. Additionally, the precooling refrigeration circuit 42 reduces the cooling requirements, and thus the compression requirements, of the main refrigeration circuit 40. As a result, in the embodiment of FIG. 1, a portion of the cooling power of the system can be effectively transferred from the main refrigeration circuit 40 to the precooling refrigeration circuit 42, resulting in a reduction in the overall energy usage and power requirements for the liquefaction of the hydrogen gas feed stream (less energy is required for the Carnot cycle process at higher temperatures).

[0048]

[0048] In an alternative embodiment of the system of the present disclosure, the system of FIG. 1 can be reconfigured to liquefy helium gas by removing heat exchangers 26e and 26f and adding an expansion device such as a JT valve downstream of heat exchanger 26d. As a result, in such a system, the stream 58 is expanded by the JT valve after passing through heat exchangers 26a - 26d. By way of mere example, in such a system, helium can be used as the refrigerant in the main refrigeration circuit and nitrogen can be used as the cryogenic liquid in the pre-cooling refrigeration circuit.

[0049]

[0049] Although the preferred embodiments of the present disclosure have been shown and described, it will be apparent to those skilled in the art that these can be changed and modified 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 an ultra-low temperature gas supply stream, comprising: a. A precooling heat exchanger including a precooling refrigerant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a supply gas cooling passage; b. A precooling refrigeration circuit, comprising: i. A precooling compressor configured to receive and compress precooling refrigerant vapor from the precooling refrigerant heating passage of the precooling heat exchanger; ii. A precooling cooling device configured to receive and cool the precooling refrigerant compressed by the precooling compressor; iii. A precooling expansion device configured to receive and expand the precooling refrigerant compressed and cooled by the precooling cooling device; iv. A precooling separation device configured to receive the expanded precooling refrigerant at a low pressure from the precooling expansion device, lower the boiling point of the expanded precooling refrigerant, and 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; The precooling refrigeration circuit including; c. A liquefier heat exchanger including a main refrigerant cooling passage, a main refrigerant heating passage, and a supply gas cooling passage; d. A main refrigeration circuit, comprising: i. A first main compressor configured to receive and compress main refrigerant vapor from the main refrigerant heating passages of the liquefier heat exchanger and the precooling heat exchanger; ii. A main cooling device configured to receive and cool the main refrigerant compressed by the first main compressor, the main cooling device having an outlet in fluid communication with the main refrigerant cooling passages of the precooling heat exchanger and the liquefier heat exchanger; iii. A first main expansion device configured to receive and expand the main refrigerant compressed and cooled in the 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 passages of the liquefier heat exchanger and the precooling heat exchanger; The main refrigeration circuit including; e. The precooling heat exchanger configured such that the main refrigerant in the main refrigerant cooling passage of the precooling heat exchanger and the ultra-low temperature gas in the supply gas cooling passage are cooled by the precooling refrigerant in the precooling refrigerant heating passage and the main refrigerant in the main refrigerant heating passage; f. The liquefier heat exchanger configured such that the main refrigerant in the main refrigerant cooling passage is cooled and the ultra-low temperature fluid in the supply gas cooling passage is liquefied by the main refrigerant in the main refrigerant heating passage; A system comprising the above.

2. The system according to claim 1, further comprising a precooling cold box in which the precooling heat exchanger is disposed, and a liquefier cold box in which the liquefier heat exchanger is disposed.

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-Thompson valve.

5. The liquefaction heat exchanger includes a first liquefaction heat exchanger having a first main refrigerant cooling passage, a first main refrigerant heating passage, and a second main refrigerant heating passage, and the liquefaction heat exchanger also includes a second liquefaction heat exchanger having a second main refrigerant cooling passage, a third main refrigerant cooling passage, a third main refrigerant heating passage, and a fourth main refrigerant heating passage. g. A dividing portion configured to receive the main refrigerant exiting the first main refrigerant passage cooling passage. h. A second main expansion device configured to receive a first portion of the main refrigerant from the dividing portion, the second main expansion device having a second main expansion device outlet. i. The second main refrigerant cooling passage of the second heat exchanger configured to receive and cool the first portion of the main refrigerant from the second main expansion device outlet, the second main refrigerant cooling passage of the second heat exchanger 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 configured to receive and cool a second portion of the main refrigerant from the dividing portion, the third main refrigerant cooling passage of the second heat exchanger being in fluid communication with the fourth and second main refrigerant heating passages. The system according to claim 1, further comprising the above.

6. The system according to claim 5, wherein the second main expansion device is a turbine.

7. The system according to claim 5, further comprising a third main expansion device configured to receive the first portion of the 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, and the third and first main refrigeration passages being configured to receive the first portion of the main refrigerant from the 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 configured to receive a second portion of the main refrigerant from the second main refrigerant heating passage of the first heat exchanger, the system further comprising a second main compressor having a main compressor inlet configured to receive the main refrigerant from the first main refrigerant heating passage and to receive the main refrigerant from the first main compressor.

10. The system according to claim 1, wherein the cryogenic gas supply stream contains hydrogen, the main refrigerant contains hydrogen, and the precooling refrigerant contains nitrogen.

11. The system according to claim 1, wherein the precooling refrigerant is nitrogen, and the pressure in the precooling separation device is reduced to about 0.05 MPa (0.5 bar) so as to lower the boiling temperature of the nitrogen from 78 K to about 73 K.

12. The system according to 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 less than 77 K.

13. A method for liquefying a cryogenic gas supply stream, comprising: a. precooling the cryogenic gas supply stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream; b. liquefying the precooled cryogenic fluid stream using the main refrigerant; c. step a forming a warmed precooling refrigerant and steps a and b forming a warmed main refrigerant; d. compressing the warmed precooling refrigerant to form a compressed precooling refrigerant; e. cooling the compressed precooling refrigerant to form a cooled precooling refrigerant; f. expanding the cooled precooling refrigerant to form an expanded precooling refrigerant; g. reducing the pressure of the expanded precooling refrigerant to lower the boiling point of the precooling refrigerant; h. separating the precooling refrigerant of step g into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream; i. vaporizing the precooling refrigerant liquid stream during the precooling of step a; j. warming the precooling refrigerant vapor stream during the precooling of step a; k. compressing the warmed 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 that is warmed during the precooling of step a and the liquefaction of step b. The method including the above steps.

14. The method according to claim 13, wherein the cryogenic gas supply stream contains hydrogen, the precooling refrigerant contains nitrogen, and the main refrigerant contains hydrogen.

15. The method according to claim 13, wherein the cooling in steps e and h is performed using water.

16. The method according to claim 13, wherein the cooling in step h includes cooling by the precooling refrigerant.

17. The method according to claim 13, wherein the precooling refrigerant is nitrogen, and the pressure in the precooling separation device is reduced to about 0.05 MPa (0.5 bar) in step g so as to lower the boiling temperature of the nitrogen from 78 K to about 73 K.

18. The method according to claim 13, wherein the pressure in the precooling separation device is reduced in step g to a level at which the boiling temperature of the precooling refrigerant is less than 77 K.

19. A system for cooling a cryogenic gas supply stream, comprising: a. A precooling heat exchanger including a precooling refrigerant heating passage, a main refrigerant cooling passage, a main refrigerant heating passage, and a supply gas cooling passage; b. A precooling refrigeration circuit, comprising: i. A precooling compressor configured to receive and compress precooling refrigerant vapor from the precooling refrigerant heating passage of the precooling heat exchanger; ii. A precooling cooling device configured to receive and cool the compressed precooling refrigerant from the precooling compressor; iii. A precooling expansion device configured to receive and expand the compressed and cooled precooling refrigerant from the precooling cooling device; iv. A precooling separation device configured to receive the expanded precooling refrigerant at a low pressure from the precooling expansion device, lower the boiling point of the expanded precooling refrigerant, and 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; A precooling refrigeration circuit including; c. A cooling heat exchanger including a main refrigerant cooling passage, a main refrigerant heating passage, and a supply gas cooling passage; d. A main refrigeration circuit, comprising: i. A first main compressor configured to receive and compress main refrigerant vapor from the main refrigerant heating passages of the cooling heat exchanger and the precooling heat exchanger; ii. A main cooling device configured to receive and cool the 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 precooling heat exchanger and the cooling exchanger; iii) A first main expansion device configured to receive and expand the main refrigerant compressed and cooled from the 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 precooling heat exchanger A main refrigeration circuit including e. The precooling heat exchanger configured such that the main refrigerant in the main refrigerant cooling passage of the precooling heat exchanger and the cryogenic gas in the supply gas cooling passage are cooled by the precooling refrigerant in the precooling refrigerant heating passage and the main refrigerant in the main refrigerant heating passage f. The cooling heat exchanger configured such that the main refrigerant in the main refrigerant cooling passage is cooled and the cryogenic fluid in the supply gas cooling passage is cooled by the main refrigerant in the main refrigerant heating passage A system comprising **Claim 20** A method for cooling a cryogenic gas supply stream, comprising a. Precooling the cryogenic gas supply stream using a precooling refrigerant and a main refrigerant to form a precooled cryogenic fluid stream b. Cooling the precooled cryogenic fluid stream using the main refrigerant c. Step a forms a heated precooling 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 precooling refrigerant to form a cooled precooling refrigerant f. Expanding the cooled precooling refrigerant to form an expanded precooling refrigerant g. Lowering the pressure of the expanded precooling refrigerant to lower the boiling point of the precooling refrigerant h. Separating the precooling refrigerant of step g into a precooling refrigerant vapor stream and a precooling refrigerant liquid stream i. Vaporizing the precooling refrigerant liquid stream during the precooling of 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 that is heated during the precooling of step a and the cooling of step b A method including

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