System and method for cooling fluid comprising hydrogen or helium

Abstract

A system for cooling a feed stream comprising hydrogen or helium with a mixed refrigerant includes a pre-cooled heat exchanger. The compression system has an inlet in fluid communication with the pre-cooling heat exchanger and receives and increases the pressure of a refrigerant vapor stream comprising hydrogen and / or helium mixed with at least one other refrigerant such that the mixture has a molecular weight greater than 6 kg / kgmol. The compression system has an outlet in fluid communication with the pre-cooled heat exchanger. A first refrigerant separation device receives fluid from the pre-cooled heat exchanger and has a liquid outlet and a vapor outlet in fluid communication with the pre-cooled heat exchanger. A refrigerant purifier has a purifier inlet in fluid communication with the vapor outlet of the first refrigerant separation device and an outlet in fluid communication with the pre-cooling heat exchanger.

Description

[0001] Priority claim

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 342,338, filed May 16, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention generally relates to systems and methods for liquefying gases and, more particularly, to systems and methods for liquefying fluids containing hydrogen or helium. Background Art

[0004] Industrial gases, such as natural gas or hydrogen, 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, and hydrogen is 1 / 848). Liquefied gases are typically evaporated back to the gaseous state for use on site or in a system.

[0005] Gaseous hydrogen is converted to liquid hydrogen by cooling it to below about 20-25 K. The typical cooling process utilizes a large amount of energy and is very expensive in terms of equipment cost. The process may include multiple refrigeration cycles and involve multiple stages of gas compression.

[0006] Prior art hydrogen liquefaction systems typically use reciprocating compressors or screw compressors. It is desirable to have a system and / or process that can use a dynamic compressor for hydrogen liquefaction. Dynamic compressors are more reliable than reciprocating compressors and more efficient than screw compressors. Dynamic compressors include compressors that do not require positive displacement, such as centrifugal compressors, radial flow compressors, or axial flow compressors. In prior art liquefaction systems, dynamic compressors are not well suited for low molecular weight gases (<6kg / kgmol), such as hydrogen or helium.

[0007] An example of a prior art hydrogen liquefaction system is presented in U.S. Pat. No. 3,992,167 to Beddome, which describes a process in which propane is added to hydrogen so that the compressed refrigerant circulating stream is 33% propane and 67% hydrogen. Additional components having higher molecular weights than propane are desirable to increase the efficiency of the process by allowing more compression power to be used for the hydrogen or helium, and to simplify the separation of the additional components from the hydrogen or helium. The process of Beddome's '167 patent also contains a single adsorption purification unit for delivering the hydrogen stream to the coldest part of the process. This results in uncondensed hydrocarbons being vented from the process when the adsorbent is regenerated. A process having near zero hydrocarbon emissions is desirable and may be particularly important in light of environmental regulations.

[0008] Grenier's U.S. Pat. No. 5,579,655 describes a prior art process in which small amounts of saturated C2, C3, and optionally C4 and C5 hydrocarbons are mixed with hydrogen to form a mixed refrigerant. The process includes a separate hydrogen feed stream that is liquefied and not mixed with the mixed refrigerant stream, thus requiring dual cryogenic purifiers at 75-80K. Purification of hydrogen from small amounts of mixed refrigerant components is more complicated due to the inclusion of ethane in the mixed refrigerant, and a liquid propane scrubber is required for separation, resulting in the need for continuous hydrocarbon replenishment to compensate for hydrocarbons lost to the environment. The liquid propane scrubber also adds cost and complexity to the process.

[0009] U.S. Patent 10,928,127 to Cardella et al. describes a process for hydrogen liquefaction using a mixed refrigerant. The mixed refrigerant mentioned contains nitrogen, neon, argon and hydrocarbons, but does not contain hydrogen or helium. The mixed refrigerant of the present invention described herein must contain hydrogen or helium. In addition, the process described in U.S. Patent 10,928,127 also uses a substantially pure hydrogen gas stream, which requires a positive displacement compressor as a separate refrigerant in addition to the mixed refrigerant. The process described in U.S. Patent 10,928,127 does not provide for precooling of the hydrogen feed below 85K. This increases the refrigeration load of the hydrogen refrigerant compared to the standard process using liquid nitrogen precooling or the invention described herein.

[0010] Muenger, U.S. Pat. No. 3,490,245, describes a heat exchanger for removing trace impurities, including carbon dioxide, hydrogen sulfide, carbon disulfide, and carbonyl sulfide, from an ammonia synthesis feed by freezing the trace impurities out of the stream being purified. It has been demonstrated that this type of heat exchanger can be used in place of an adsorption system to remove impurities that would otherwise freeze in a cold box heat exchanger. A freezing device is defined as a device that removes one or more impurities from a mixed stream by selectively freezing one or more specific components. The device described in U.S. Pat. No. 3,490,245 is an example of a freezing device. Summary of the invention

[0011] 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 together is not intended to exclude the use of these aspects alone or the separate claims or different combinations of these aspects, as set forth in the appended claims.

[0012] In one aspect, a system for cooling a feed stream containing hydrogen or helium with a mixed refrigerant includes a precooling heat exchanger having a feed stream cooling channel, a first refrigerant cooling channel, a second refrigerant cooling channel, and a refrigerant heating channel. A compression system has an inlet in fluid communication with the refrigerant heating channel and is configured to receive and increase the pressure of a refrigerant vapor stream of hydrogen and / or helium mixed with at least one other refrigerant so that the molecular weight of the mixture is greater than 6 kg / kgmol. The compression system has an outlet in fluid communication with the first refrigerant cooling channel. A first refrigerant separation device is configured to receive fluid from the first refrigerant cooling channel in the precooling heat exchanger. The first refrigeration separation device has a liquid outlet and a vapor outlet in fluid communication with the refrigerant heating channel.

[0013] The refrigerant purifier has a purifier inlet in fluid communication with the vapor outlet of the first refrigerant separation device and an outlet in fluid communication with the second refrigerant cooling passage. The second refrigerant cooling passage has an outlet in fluid communication with the refrigerant heating passage.

[0014] On the other hand, a method for liquefying a feed stream comprising hydrogen or helium includes the steps of: mixing a hydrogen or helium refrigerant with at least one additional refrigerant component having a molecular weight higher than that of hydrogen or helium to form a mixed refrigerant having a molecular weight of at least 6 kg / kgmol; compressing the mixed refrigerant using a dynamic compressor; separating the at least one additional refrigerant component from the hydrogen or helium refrigerant at a temperature of 75K or higher to obtain a remaining hydrogen or helium refrigerant; and cooling the hydrogen or helium feed stream using the remaining hydrogen or helium refrigerant to produce a liquid hydrogen or helium product from the feed stream.

[0015] In another aspect, a system for cooling a cryogenic fluid feed stream containing hydrogen or helium with a mixed refrigerant includes a precooling heat exchanger having a precooling feed stream cooling passage, a low-pressure refrigerant heating passage, an intermediate-pressure refrigerant heating passage, a first refrigerant cooling passage, and a second refrigerant cooling passage. A mixed gas compressor is configured to receive a mixed refrigerant vapor stream from the low-pressure refrigerant heating passage. A mixed gas aftercooler is in fluid communication with the mixed gas compressor. A mixing device has a first inlet, a second inlet, and a mixing device vapor outlet in fluid communication with the mixed gas aftercooler. The second inlet is configured to receive a mixed refrigerant vapor stream from the intermediate-pressure refrigerant heating passage. A first interstage compressor is in fluid communication with the mixing device vapor outlet. A first interstage aftercooler is in fluid communication with a first interstage compressor. A high-pressure accumulator is in fluid communication with the first interstage aftercooler and has a high-pressure accumulator vapor outlet and a high-pressure accumulator liquid outlet. The high-pressure accumulator vapor outlet is in fluid communication with the first refrigerant cooling passage, and the high-pressure accumulator liquid outlet is in fluid communication with the intermediate-pressure refrigerant heating passage. The first refrigerant separation device is in fluid communication with the first refrigerant cooling passage and has a first refrigerant separation device liquid outlet in fluid communication with the low-pressure refrigerant heating passage and a first refrigerant separation device vapor outlet in fluid communication with the second refrigerant cooling passage. The second refrigerant separation device is in fluid communication with the second refrigerant cooling passage and has a second refrigerant separation device liquid outlet in fluid communication with the low-pressure refrigerant heating passage and a second refrigerant separation device vapor outlet. The refrigerant purifier has a purifier inlet in fluid communication with the second refrigerant separation device vapor outlet and a purifier outlet, wherein the purifier outlet is in fluid communication with the low-pressure refrigerant heating passage and the medium-pressure refrigerant heating passage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a process flow diagram illustrating a first embodiment of a pre-cooling portion of an embodiment of the system of the present disclosure.

[0017] Figure 2 is a process flow diagram illustrating an embodiment of a liquefaction portion of an embodiment of the disclosed system.

[0018] Figure 3 is a process flow diagram illustrating a second embodiment of a pre-cooling portion of an embodiment of the system of the present disclosure.

[0019] Figure 4 is a process flow diagram illustrating a third embodiment of a pre-cooling portion of an embodiment of the system of the present disclosure.

[0020] Figure 5 is a process flow diagram illustrating a fourth embodiment of a pre-cooling portion of an embodiment of the system of the present disclosure. DETAILED DESCRIPTION

[0021] 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.

[0022] In addition, as used herein, and as known in the art, a heat exchanger is a device or 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" or the like generally refers to fluid communication. And although the two fluids in communication may exchange heat when mixed, this exchange is different from the heat exchange in a heat exchanger, although this exchange may occur in a heat exchanger.

[0023] As used herein, the terms "high," "medium," "hot," "cold," and the like are relative to comparable flows, as is common parlance in the art.

[0024] By way of non-limiting example only, any tower mentioned in the following description may be a spray tower, a packed tower, a tray tower, and / or any combination thereof.

[0025] 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 to provide context for the other features.

[0026] 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 method steps and are not intended to indicate the order in which the claimed steps should be performed, unless and only to the extent such an order is specifically recited in the claims.

[0027] The disclosed embodiments described below provide processes and apparatus for liquefying hydrogen or helium, the type of which uses a refrigeration cycle and an optional closed supplementary refrigerant refrigeration cycle, the circulating fluid of which mainly includes hydrogen or helium. The main refrigeration cycle fluid is a mixture containing hydrogen or helium and at least one additional component having a higher molecular weight and a higher boiling point, which is compressed outside the cold box and used to provide cooling for the hydrogen or helium feed stream in the cold box. One or more additional components are removed from the hydrogen-rich or helium-rich refrigerant stream in the cold box by a series of preferential partial condensation steps and adsorption and / or freezing and / or distillation at a temperature below ambient temperature and above about 75K. The removed components provide cooling for the cold box because they are flashed to low pressure, reheated, and recycled back to a certain point in the compression chain. In at least one interstage compression drum operated as a direct contact mixing vessel, a controlled direct heat transfer and mass transfer process step is included between hydrogen or helium and one or more additional components, providing simultaneous heat transfer and mass transfer, ensuring the evaporation of high molecular weight components and the control of the composition, molecular weight and thermal properties of the mixed refrigerant stream in all cases. The remaining cryogenically purified hydrogen or helium is used as the primary refrigerant at a temperature below about 75-80K.

[0028] Increasing the molecular weight of the compressed hydrogen or helium containing stream by mixing in other components which are subsequently removed allows the use of dynamic compressors in the compression of the mixed refrigerant in place of less reliable reciprocating compressors.

[0029] In addition, the use of higher molecular weight components than the prior art in the examples described below improves compressor performance while maintaining a relatively high hydrogen concentration in the mixture. The use of fluorinated hydrocarbons increases the molecular weight of the added component, which reduces the amount required to increase the molecular weight of the mixture, thereby increasing the hydrogen or helium concentration in the mixture.

[0030] The embodiments disclosed below reduce the power required for the supplemental refrigerant precooling cycle by utilizing the supplemental refrigeration load provided by the higher molecular weight component. This supplemental refrigeration load occurs primarily above about 190K. These improvements increase the overall efficiency of the precooling process. Excess supplemental refrigeration load can be supplied in excess of the needs of the hydrogen / supplemental refrigerant precooling system, and this excess load can provide refrigeration for other processes or systems.

[0031] The embodiments disclosed below also use a refrigerant mixture that does not contain hydrocarbons that boil at temperatures below about 190 K. Removing ethane and ethylene from the mixture proposed in the prior art significantly simplifies and improves the separation of hydrocarbons from a hydrogen or helium stream before it is fed to the cold end process. The description of the figures relates to the case where hydrogen is the feed stream and the material to be liquefied. If helium is used, there is no normal-secondary conversion catalyst and the final temperature is lower, but the description applies generally.

[0032] In one embodiment, if Figure 1 As shown, the high pressure hydrogen feed 101 at about 14-26 bar and near ambient temperature is cooled to about 77-80K in the pre-cooling heat exchanger 1 and leaves as pre-cooled hydrogen feed 102. As is known in the prior art, the pre-cooling heat exchanger 1 is located inside the insulated cold box 7. The pre-cooling heat exchanger 1 can be filled with an ortho-para conversion catalyst 2 in the hydrogen cooling channel to promote the conversion of a portion of the high pressure hydrogen feed 101 from ortho-hydrogen to para-hydrogen. The pre-cooled hydrogen feed 102 is sent to an adsorption-based cryogenic purifier (51, such as the second refrigerant purifier 23) similar to the second refrigerant purifier 23. Figure 2 ), and hydrogen liquefaction processes in which a large portion of the hydrogen is liquefied are well known in the art ( Figure 2 An example is shown in ). A small portion of the pre-cooled hydrogen feed is returned to the pre-cooling heat exchanger 1 as a cold hydrogen recycle stream 103.

[0033] The cold hydrogen recycle stream 103 is heated in the pre-cooling heat exchanger 1 to provide cooling for the high pressure hydrogen feed 101. The cold hydrogen recycle will be at a lower pressure than the high pressure hydrogen feed 101. This stream can optionally pass through the positive secondary conversion catalyst 3 to utilize the additional cooling capacity available in the conversion. The cold hydrogen recycle stream 103 leaves the pre-cooling heat exchanger 1 as a hot hydrogen recycle stream 104, which can be compressed and returned to the process as part of the high pressure hydrogen feed 101.

[0034] In many cases, an optional high pressure supplemental refrigerant such as nitrogen 111 is cooled in the pre-cooling heat exchanger 1 to form a cold high pressure supplemental refrigerant stream 112, which is expanded in the supplemental refrigerant expander 4 to form a cold supplemental refrigerant stream 113. The cold supplemental refrigerant stream 113 provides cooling for the pre-cooling heat exchanger 1 and exits as a hot low pressure supplemental refrigerant stream 114, which is compressed in the supplemental refrigerant compressor 5 to form a hot compressed supplemental refrigerant stream 115, which is cooled in the supplemental refrigerant compressor aftercooler 6 to form the high pressure supplemental refrigerant feed 111. The supplemental refrigerant compressor 5 and aftercooler 6 may consist of more than one stage, depending on the pressure increase required. Likewise, the supplemental refrigerant expander 4 may also consist of more than one stage. Alternatively, the cycle may be enhanced to include more efficient schemes, such as Figure 3 The scheme shown.

[0035] A low-pressure gas mixture 121 consisting of hydrogen and / or helium and at least one other substance having a higher molecular weight and a boiling point above 80 K is compressed in the first mixed gas compressor 11 and cooled in the first compressor aftercooler 12 to form a first medium-pressure mixture 122 that can be sent to the mixing container 13. The first mixed gas compressor 11 can be a single-stage compressor, a compressor with more than one stage, or the lowest pressure stage of a multi-stage compressor. The mixing container 13 is designed to operate with or without a liquid level and contains sprayers and / or heating coils, packings or other devices to enhance direct contact and heat and mass transfer between inlet flows. Examples of these other substances include hydrocarbons, halogenated hydrocarbons, perfluorocarbons, neon and other refrigerants. The second mixture 123 leaves the mixing container 13 and is compressed in the second mixed gas compressor 14 and cooled in the second compressor aftercooler 15 to form a second medium-pressure mixture 124, which is fed to the first phase separator or interstage separation device 16, which is designed to remove any small amount of liquid that may be formed. The second mixed gas compressor 14 can be a single stage compressor, a compressor having more than one stage, or one or more stages of a multi-stage compressor operating at a higher pressure than the first mixed gas compressor. Controlled operation of the heat input to the mixing vessel 13 maximizes the amount of higher molecular weight components in the second mixture 123 by allowing the mixture to operate at or near its saturation or dew point conditions. This increases the molecular weight of the second mixture and increases its ability to be compressed. The third mixture 125 leaves the interstage separation device 16 and is compressed in the third mixed gas compressor 17 and cooled in the third compressor aftercooler 18 to form a high pressure mixture 126, which is fed to the second phase separator or high pressure accumulator 19. The third compressor can be a single stage compressor, a compressor having more than one stage, or one or more stages of a multi-stage compressor operating at a higher pressure than the second compressor. As Figure 1 As shown, in all the following embodiments, the first, second and third mixed gas compressors 11 , 14 and 17 are located outside the cold box 7 .

[0036] The first liquid 160 leaves the bottom of the interstage separation device 16 and can be discharged through the first phase separator valve 41 to form a low-pressure first liquid 161. The second liquid 162, which mainly contains high molecular weight components in the original mixture, leaves the bottom of the high-pressure accumulator 19 and can be discharged through the second phase separation valve 42 to form a low-pressure second liquid 163, and mixes with the low-pressure first liquid 161 to form a low-pressure mixed liquid 164.

[0037] The low pressure mixed liquid 164 can be distributed in four different streams, namely a mixing container recycle stream 170, a mixing container refrigeration feed 166, a low pressure gas mixture container refrigeration feed 167, and a low pressure gas mixture container recycle stream 172. The mixing container recycle stream 170 is expanded through the mixing container valve 43 to form a low pressure mixing container recycle stream 171, which is returned to the mixing container 13. The mixing container refrigeration feed 166 is expanded through the mixing container refrigeration expansion device 45 (e.g., a valve) to form a cooled mixing container refrigerant 169, which provides cooling to the pre-cooling heat exchanger 1 and returns to the mixing container 13. A portion of the cooled mixing container refrigerant 174 can be sent through the pre-cooling heat exchanger 1 as a separate stream so that it leaves the pre-cooling heat exchanger 1 as a two-phase stream. This can reduce the temperature difference in the heat exchanger and improve efficiency. The low-pressure gas mixture container refrigeration feed 167 is expanded by a low-pressure mixture container refrigeration expansion device 46 (e.g., a valve) to form a cooled low-pressure gas mixture container refrigerant 168, which provides cooling to the pre-cooling heat exchanger 1 and returns to the low-pressure gas mixture container 24. The low-pressure gas mixture container recycle stream 172 is expanded by a low-pressure gas mixture container valve 44 to form a decompressed gas mixture container recycle stream 173, which returns to the low-pressure gas mixture container 24. The accumulated liquid 175 from the mixing container 13 can be pressurized using a mixing container pump 49 to form a pressurized accumulated liquid 176 and mixed with the first liquid 160 or the second liquid 162. The pump 49 and the mixing container 13 allow the molecular weight of the compressor feed stream to be controlled and maintained at a relatively high level. Alternatively (not shown), the accumulated liquid 175 can be mixed with the low-pressure gas mixture container feed 143 and supplied to the low-pressure gas mixture container 24.

[0038] The second phase separator vapor 127 leaves the top of the high pressure accumulator 19 and is cooled in the pre-cooling heat exchanger 1 to form a first cooled mixed refrigerant 128, which is fed to the first mixed refrigerant separator 20. The first mixed refrigerant vapor 129 leaves the top of the first mixed refrigerant separator 20 and returns to the pre-cooling heat exchanger 1, where it is further cooled to form a second cooled mixed refrigerant stream 130, which is fed to the second mixed refrigerant separator 21. The second mixed refrigerant vapor 131 leaves the top of the second mixed refrigerant separator 21 and is purified in the mixed refrigerant purifier 22, which substantially removes all mixture components with a boiling point above 80 K. The mixed refrigerant purifier 22 can be an adsorption system that preferentially removes mixture components with a boiling point above 80 K. The adsorption system is typically composed of more than one adsorption bed, so that one or more beds can be regenerated while another one or more beds are active. A freezing device, a distillation column or other purification method can also be used as a refrigerant purifier. The freezing device will require similar regeneration. Mixed refrigerant purifier regeneration feed 191 is used to remove captured impurities from mixed refrigerant purifier 22 to regenerate it for a new feed step. Purifier regeneration feed is usually composed of nitrogen, hydrogen, helium or a mixture thereof. Regeneration is usually carried out at a pressure lower than the typical operating pressure and temperature of the purifier and at a higher temperature. When there are at least two mixed refrigerant purifiers, trace heavy refrigerant components in the first purifier can be selectively removed without removing lighter impurities such as nitrogen or argon introduced with the feed. The impurity-containing regeneration stream 192 can be recycled to the inlet of the first mixed gas compressor or the low-pressure gas mixing container 24. This allows the system to recycle trace amounts of other substances in the mixed refrigerant removed in the refrigerant purifier 22. In the case where hydrocarbons are used as another substance, unlike the process in the prior art, this ensures that hydrocarbons are basically completely recovered and essentially zero hydrocarbon emissions.

[0039] The purified hydrogen / helium stream 132 leaves the mixed refrigerant purifier 22 and returns to the precooling heat exchanger 1, where it is further cooled and leaves as a cooled refrigerant 133, which is further purified in the second refrigerant purifier 23, which is similar to the mixed refrigerant purifier 22, except that the second refrigerant purifier is designed to remove lighter impurities, including nitrogen and argon, while the mixed refrigerant purifier is designed to remove higher molecular weight substances with boiling points above 80K. Low temperature refrigerant 134 leaves the second refrigerant purifier 23 and is supplied to the hydrogen liquefaction process. Similar to the mixed refrigerant purifier 22, the second refrigerant purifier regeneration feed 193 is used to regenerate the second refrigerant purifier 23. All or part of the second impurity-containing regeneration stream 194 can be recycled to the crude hydrogen purifier (not shown) or discharged, because nitrogen, argon and other light impurities will accumulate to unacceptably high concentrations if not removed. Alternatively, a portion of the regeneration stream can be recycled to the compressor inlet, depending on its pressure. The crude hydrogen purifier is a device located upstream of the high pressure hydrogen feed 101 and can be, for example, a pressure swing adsorption system that separates hydrogen from other components in a mixture produced by a hydrogen production system such as a reformer or electrolyzer. In an alternative, the two refrigerant purifiers can be combined into a single unit. In this case, the regeneration stream can be recycled to the crude hydrogen purifier, or a portion of the regeneration stream can be recycled to the compressor inlet, depending on its pressure.

[0040] The first mixed refrigerant liquid 181 exits the bottom of the first mixed refrigerant separator 20 and expands in the first mixed refrigerant liquid expansion device 47 (e.g., a valve) to cool the stream and reduce its pressure, thereby forming a cooled low-pressure first mixed refrigerant liquid stream 182. The second mixed refrigerant liquid 184 exits the bottom of the second mixed refrigerant separator 21 and expands in the second mixed refrigerant liquid expansion device 48 (e.g., a valve) to cool the stream and reduce its pressure, thereby forming a cooled low-pressure second mixed refrigerant liquid stream 185. The cooled low-pressure first mixed refrigerant liquid stream 182 and the cooled low-pressure second mixed refrigerant liquid stream 185 are combined to form a low-pressure mixed refrigerant recycle stream 183, which enters the pre-cooling heat exchanger 1 to provide cooling.

[0041] The low pressure refrigerant 141 is recycled from the hydrogen liquefaction process and enters the pre-cooling heat exchanger 1 to provide cooling. The low pressure refrigerant 141 is mixed with the cooling low pressure gas mixture container refrigerant 168 and the low pressure mixed refrigerant recycle stream 183 in the pre-cooling heat exchanger 1 and leaves as the heated mixed refrigerant 142, which is combined with the depressurized gas mixture container recycle stream 173 to produce the low pressure gas mixture container feed 143 entering the low pressure gas mixture container 24.

[0042] The medium pressure refrigerant 151 leaves the hydrogen liquefaction process and enters the pre-cooling heat exchanger 1 to provide cooling. The medium pressure refrigerant 151 mixes with the cooling mixing vessel refrigerant 169 in the pre-cooling heat exchanger 1 and leaves as the mixing vessel recycle feed 152 entering the mixing vessel 13.

[0043] Figure 2 A cold end process for producing a liquid hydrogen product is shown. There are many variations of this configuration known in the art that may be suitable for the technology of this disclosure. Figure 2 The example shown is just one of many possible options. The cold end configuration selected has no significant impact on the disclosed technique or its use.

[0044] From Figure 1 The pre-cooled hydrogen feed 102 enters the hydrogen feed purifier 51, similar to Figure 1 The second refrigerant purifier in the reactor. The hydrogen feed purifier removes any impurities in the hydrogen feed before the stream is further cooled. These impurities are typically composed primarily of nitrogen and argon and other trace components that may be frozen in the cryogenic heat exchanger. The purified hydrogen feed 201 leaves the hydrogen feed purifier 51 and enters the first cold heat exchanger 53, where it is cooled and a portion of the orthohydrogen is converted to parahydrogen on a conversion catalyst located in the first cold heat exchanger catalyst channel 52 to produce a second purified hydrogen feed 202.

[0045] The second purified hydrogen feed 202 leaves the first cold heat exchanger 53 and enters the second cold heat exchanger 55, where a portion of the orthohydrogen is converted to parahydrogen on the conversion catalyst located in the second cold heat exchanger catalyst channel 54 to produce the third purified hydrogen feed 203. The third purified hydrogen feed 203 leaves the second cold heat exchanger 55 and enters the third cold heat exchanger 57, where a portion of the orthohydrogen is converted to parahydrogen on the conversion catalyst located in the third cold heat exchanger catalyst channel 56 to produce the fourth purified hydrogen feed 204. The fourth purified hydrogen feed 204 leaves the third cold heat exchanger 57 and enters the fourth cold heat exchanger 59, where a portion of the orthohydrogen is converted to parahydrogen on the conversion catalyst located in the fourth cold heat exchanger catalyst channel 58 to produce the fifth purified hydrogen feed 205. If desired, the cold heat exchangers can be combined into one, two or three heat exchangers with side feeds and outlets. In most cases, these heat exchangers will be combined to reduce capital costs, piping, connections and cold box volume. The combination of selected heat exchangers does not affect the technology of the present invention or its use.

[0046] The fifth purified hydrogen feed 205 is expanded through an expansion device such as a hydrogen product expansion valve 60 to form a two-phase hydrogen feed 206, which is separated in a hydrogen product separator 61. Liquid hydrogen product 207 is removed from the bottom of the separator. Cold hydrogen vapor 208 is removed from the top of the separator and is supplied to the fourth cold heat exchanger 59, the third cold heat exchanger 57, the second cold heat exchanger 55 and the first cold heat exchanger 53, where it is heated to provide cooling of the hydrogen feed. The cold hydrogen vapor 208 forms a first hot hydrogen vapor stream 209, a second hot hydrogen vapor stream 210 and a third hot hydrogen vapor stream 211 after leaving the fourth heat exchanger 59, the third heat exchanger 57 and the second heat exchanger 55, respectively, and leaves the heat exchangers as a cold hydrogen recycle stream 103, such as Figure 1 and 2 shown.

[0047] Low temperature refrigerant 134 leaves Figure 1 The second refrigerant purifier 23 shown is supplied to Figure 2 The first hydrogen expander feed 222 is expanded in the first hydrogen expander 62 to produce a first hydrogen expander product 224, which is used to provide cooling in the second cold heat exchanger 55, exits as a heated first hydrogen expander product 225, and exits the first cold heat exchanger 53 before exiting as the intermediate pressure refrigerant 151, as shown in FIG. Figure 1 and 2 As shown. The second cold heat exchanger refrigerant feed 223 is supplied to the second cold heat exchanger 55 and leaves as a second hydrogen refrigerant 226, which is split between the second expander feed 227 and the third cold heat exchanger refrigerant feed 231. The second expander feed 227 is expanded in the second hydrogen expander 63 to produce a second hydrogen expander product 228, which is used to provide cooling in the third cold heat exchanger 57.

[0048] The third cold heat exchanger refrigerant feed 231 is fed to the third cold heat exchanger 57 and exits as a third hydrogen refrigerant 232, which is fed to the hydrogen refrigerant expansion valve 64 to form a two-phase hydrogen refrigerant 233, which is separated in the refrigerant separator 65. Liquid refrigerant 237 is removed from the bottom of the separator and provides cooling in the fourth cold heat exchanger 59, where it is at least partially evaporated and returned to the refrigerant separator as a second two-phase refrigerant 238. Cold hydrogen refrigerant vapor 234 is removed from the top of the refrigerant separator 65, mixed with the second hydrogen expander product 228 to form a cold refrigerant feed 229, and fed to the third cold heat exchanger 57, exits the second cold heat exchanger 55 as a second cold refrigerant feed 235, exits as a third cold refrigerant feed 236, and the first cold heat exchanger 53, where it is heated to provide cooling for the hydrogen feed. The cold refrigerant feed 229 leaves the cold heat exchanger as low pressure refrigerant 141, as Figure 1 and 2 shown. Figure 2 The heat exchangers 53, 55, 57 and 59 may be located at Figure 1 cold box 7, or they can be located in their own cold box.

[0049] Figure 2 Alternatives to the process shown include processes in which the expanders are operated in series rather than in parallel, or in which the heat exchangers are combined in any of a number of possible configurations. If helium is used as the refrigerant and the process is used to liquefy hydrogen, it is not necessary to produce liquid helium, and the refrigerant separator 65 is not necessary because there is no liquid refrigerant 237. None of these variations affect the practice and advantages of the technology described herein.

[0050] Figure 3 Another example hot end process with an improved supplemental refrigerant cooling system is shown. The supplemental refrigerant may be nitrogen or another refrigerant with appropriate refrigeration characteristics for the desired cycle. All numbers represent substantially Figure 1 The same streams or equipment as shown and described previously. This alternative includes a modified supplemental refrigerant refrigeration loop, the pre-cooled hydrogen feed 102 is mixed with the cooling refrigerant 133 and fed to a single hydrogen purifier 33 to produce a combined pre-cooled hydrogen stream 135. Other processes include the use of a modified supplemental refrigerant refrigeration loop or mixing of cold streams, but nothing else.

[0051] The advantage of combining the pre-cooled hydrogen feed 102 and the purified hydrogen stream 132 to form a combined purifier feed 135 is that only one cryogenic purifier is required for both streams and a combined purifier product 136 is produced. The disadvantage is that the two streams must be at the same pressure and the refrigerant and feed must be the same material. For example, if helium refrigerant is used to liquefy the hydrogen, the streams cannot be combined. The benefit of reducing capital costs by eliminating the second purifier and subsequently shrinking the cold box can be compared with the cost of reduced operating flexibility to determine whether mixing the streams is beneficial. In this case, as Figure 2 As shown, a portion of the combined purified product 136 is separated to form the purified hydrogen feed 201, while the remainder becomes Figure 2 A low temperature refrigerant 134 is shown.

[0052] The improved supplementary refrigerant refrigeration circuit comprises a cooled high-pressure supplementary refrigerant stream 211 which is fed to the pre-cooling heat exchanger 1. A first supplementary refrigerant portion 212 is taken from the cooled high-pressure supplementary refrigerant stream 211 and expanded in a first supplementary refrigerant expander 4 to form a first supplementary refrigerant 213 which is returned to the pre-cooling heat exchanger 1 where it provides refrigeration. A second supplementary refrigerant portion 214 is taken from the cooled high-pressure supplementary refrigerant stream 211 having a lower temperature than the first portion 212 and expanded in a second supplementary refrigerant expander 5 to form a second supplementary refrigerant 215 which is returned to the pre-cooling heat exchanger 1 where it provides refrigeration. The remaining supplementary refrigerant 217 of the cooled high-pressure supplementary refrigerant stream 211 leaves the pre-cooling heat exchanger 1 at the lowest temperature and is expanded in a supplementary refrigerant expansion valve 6 to form a cold supplementary refrigerant 218 which is returned to the pre-cooling heat exchanger 1 where it provides refrigeration. The cold supplementary refrigerant 218 is heated in the pre-cooling heat exchanger 1 to produce a heated low-pressure supplementary refrigerant recycle 219, which is compressed in the first supplementary refrigerant compressor 7 to form a compressed first supplementary refrigerant 220, and is cooled in the first supplementary refrigerant compressor aftercooler 8 to produce a first intermediate-pressure supplementary refrigerant recycle 221. The first supplementary refrigerant 213 and the second supplementary refrigerant 215 are combined in the pre-cooling heat exchanger 1 and heated to produce a heated intermediate-pressure supplementary refrigerant recycle 216, which is combined with the first intermediate-pressure supplementary refrigerant recycle 221 to produce an intermediate-pressure supplementary refrigerant 222. The intermediate-pressure supplementary refrigerant 222 is compressed in the second supplementary refrigerant compressor 9 to form a compressed intermediate-pressure supplementary refrigerant 223, and is cooled in the second supplementary refrigerant compressor aftercooler 10 to produce a cooled high-pressure supplementary refrigerant stream 211. The first supplemental refrigerant compressor and / or the second supplemental refrigerant compressor may be a single stage compressor, a compressor having more than one stage, or one or more stages of a multi-stage compressor such that the second supplemental refrigerant compressor operates at a higher pressure than the first supplemental refrigerant compressor.

[0053] In one alternative, a portion of the cooled, pressurized first supplemental refrigerant portion 251 of the first portion 212 of the high pressure supplemental refrigerant stream 211 is exported to the external process 31 for use as a refrigerant. The supplemental refrigerant is then returned to the process as a supplemental refrigerant return stream 252. The external process 31 can be any process that can utilize additional refrigeration between the temperature of the first supplemental refrigerant portion 212 and the ambient temperature. Another alternative is that a portion of the first supplemental refrigerant 213 can be exported. This has the advantage of being at a lower temperature and not requiring an additional expansion device in the external process 31, but also has a lower pressure and less driving force to move through the external process 31.

[0054] exist Figure 4 During the process, the hot mixing container refrigeration feed 165 is fed to the pre-cooling heat exchanger 1 before expansion in the mixing container refrigeration expansion device 45. This allows the cooled mixing container refrigerant 169 to be at a cooler temperature than would otherwise be possible and provide additional cooling for the process. Figure 4 Another variation shown is that the first mixed refrigerant liquid 181 is split and expanded in the first mixed refrigerant liquid expansion device 47B or the second mixed refrigerant liquid expansion device 47A (e.g., a valve) to cool the stream and reduce its pressure to form a cooled low pressure first mixed refrigerant liquid stream 182 or a second low pressure mixed refrigerant recirculation stream 183A, which has a higher pressure than the cooled low pressure first mixed refrigerant liquid stream 182. The cooled low pressure first mixed refrigerant liquid stream 182 is combined with the cooled low pressure second mixed refrigerant liquid stream 185 to form a cooled mixed refrigerant recirculation stream 183B, which is mixed with the low pressure refrigerant 141 entering the pre-cooling heat exchanger 1 to provide refrigeration for the process.

[0055] Other potential configurations capable of practicing the disclosed technology will be apparent to those skilled in the art.

[0056] Example

[0057] refer to Figure 5 The following example shows one possible method of practicing the present invention. The process produces 15 tons / day (625 kg / hour) of liquid hydrogen product. The conditions and composition of the selected streams are shown in Table 1.

[0058] The mixed refrigerant selected for this example is a mixture of hydrogen, propane, and isopentane. The molecular weight of the low pressure gas mixture 121 is ~28 kg / kgmol and the molecular weight of the second mixture 123 is ~11 kg / kgmol. These are high enough to use a dynamic compressor, which has higher reliability than a typical positive displacement compressor for hydrogen, which has a molecular weight of ~2 kg / kgmol. Other hydrocarbons or other refrigerants may be used, including halogenated hydrocarbons and partially halogenated hydrocarbons. Other compositions or ratios may also be used. Due to the conditions and refrigerant compositions in the example, Figure 4 There is no flow in streams 160, 167, 170, 172 or 175 shown, so these streams are not Figure 5 Shown in.

[0059] The high pressure hydrogen feed 101 is 373.5 kgmol / hr. The flow rate of the hot hydrogen recycle stream 104 is 35.3 kgmol / hr. This means that 338.2 kgmol / hr of hydrogen is liquefied in the process. The liquid product flow rate is 15 metric tons per day, or 310.0 kgmol / hr. The estimated losses are 7-10% or about 8.5% from the process to the truck leaving the factory gate. Most of these losses can be recovered and recycled into the feed with appropriate equipment not described here.

[0060] The refrigeration required to produce this liquid product is provided by a low pressure gas mixture 121 comprising 51.4% hydrogen, 29.4% propane and 19.2% isopentane, which is compressed to 1.2 to 4.0 bar in the first mixed gas compressor 11. This stream is mixed with the mixing vessel recycle feed 152 in the mixing vessel 13 to form a second mixture 123, and is compressed to 34.1 bar and separated in the second phase separator 19. The second liquid 162 leaving the second phase separator 19 comprises mostly isopentane and some propane and a small amount of dissolved hydrogen. This stream is cooled to 199.8K in the precooling heat exchanger 1 and recycled to the mixing vessel 13.

[0061] The second phase separator vapor 127 leaves the top of the second phase separator 19 and is cooled to 155.3K in the pre-cooling heat exchanger 1 to form a first cooling mixed refrigerant 128, which is fed to the first mixed refrigerant separator 20. The first mixed refrigerant liquid 181 containing almost all the remaining isopentane and most of the propane leaves the bottom of the first mixed refrigerant separator 20 and is divided into streams 183A and 182, stream 183A is expanded to 4.1 bar and has a molar flow rate of 45.4 kgmol / hr, and stream 182 is expanded to 1.3 bar and has a flow rate of 182.7 kgmol / hr. These two streams provide cooling in the pre-cooling heat exchanger and are recycled to the first stage (183B) and the second stage (183A) of the mixed gas compressor.

[0062] The first mixed refrigerant vapor 129 containing 99.98% hydrogen leaves the top of the first mixed refrigerant separator 20 and returns to the pre-cooling heat exchanger 1, where it is further cooled to 110.9K to form a second cooled mixed refrigerant stream 130, which is fed to the second mixed refrigerant separator 21. The second mixed refrigerant liquid 184, containing most of the remaining propane and with a flow rate of only 0.3 kgmol / hr, is discharged from the bottom of the second mixed refrigerant separator 21 and expanded in a second mixed refrigerant liquid expansion device 48 (e.g., a valve) to cool the stream and reduce its pressure before it forms part of the above-mentioned return refrigerant stream 183B.

[0063] The second mixed refrigerant vapor 131 leaves the top of the second mixed refrigerant separator 21 and is purified in the mixed refrigerant purifier 22 to remove any remaining propane, less than 1 ppm in this example. The purified hydrogen gas stream 132 leaves the mixed refrigerant purifier 22 and returns to the pre-cooling heat exchanger 1, where it is cooled to 80.1K and leaves as cooling refrigerant 133, which is further purified in the second refrigerant purifier 23, similar to the mixed refrigerant purifier 22, except that the second refrigerant purifier removes 1 ppm of nitrogen from the original hydrogen feed. The low temperature refrigerant 134 leaves the second refrigerant purifier 23 and is fed to the hydrogen liquefaction process.

[0064] After the closed loop cycle in the liquefaction process, the pure hydrogen cryogenic refrigerant is returned as two separate streams: a low pressure stream 141 and an intermediate pressure stream 151. The low pressure refrigerant 141 at 1.3 bar is recycled from the hydrogen liquefaction process and enters the pre-cooling heat exchanger 1 to provide cooling and returns to the first stage of the mixed gas compressor. The intermediate pressure refrigerant 151 at 4.1 bar leaves the hydrogen liquefaction process and enters the pre-cooling heat exchanger 1 to provide cooling and returns to the second stage of the mixed gas compressor.

[0065] Table 1 - Stream conditions and composition for Example 1

[0066]

[0067]

[0068] 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 cooling a feed stream containing hydrogen or helium with a mixed refrigerant, comprising: a pre-cooling heat exchanger having a feed stream cooling channel, a first refrigerant cooling channel, a second refrigerant cooling channel and a refrigerant heating channel; b. a compression system having an inlet in fluid communication with the refrigerant heating passage and configured to receive and increase the pressure of a refrigerant vapor stream comprising hydrogen and / or helium mixed with at least one other refrigerant such that the molecular weight of the mixture is greater than 6 kg / kgmol, the compression system having an outlet in fluid communication with the first refrigerant cooling passage; c. a first refrigerant separation device configured to receive fluid from a first refrigerant cooling passage in the pre-cooling heat exchanger, the first refrigerant separation device having a liquid outlet in fluid communication with the refrigerant heating passage, and a vapor outlet; d. a refrigerant purifier having a purifier inlet in fluid communication with the vapor outlet of the first refrigerant separation device and an outlet in fluid communication with the second refrigerant cooling passage having an outlet in fluid communication with the refrigerant heating passage.

2. The system according to claim 1, wherein: The compression system includes: a first interstage compressor having an inlet and an outlet connected to the refrigerant heating channel fluid; a first interstage aftercooler having an inlet and an outlet configured to receive fluid from the first interstage compressor; a high-pressure accumulator having an inlet connected to the first interstage aftercooler outlet fluid, the high-pressure accumulator having a vapor outlet and a liquid outlet, the vapor outlet being connected to the first refrigerant cooling channel fluid, and the liquid outlet being connected to the compression system fluid.

3. The system of claim 2 further comprising an interstage separation device having an inlet in fluid communication with the first interstage aftercooler outlet, having a vapor outlet in fluid communication with the high pressure accumulator, and a liquid outlet in fluid communication with the compression system.

4. The system according to claim 3, wherein: The refrigerant heating passage includes a low-pressure refrigerant heating passage and an intermediate-pressure refrigerant heating passage, and wherein the compression system includes a mixed gas compressor having an inlet configured to receive fluid from the low-pressure refrigerant heating passage, a mixed gas aftercooler having an inlet configured to receive fluid from the mixed gas compressor, a mixing device having a first inlet configured to receive fluid from the mixed gas aftercooler, a second inlet configured to receive fluid from the intermediate-pressure refrigerant heating passage, a third inlet, a mixing device vapor outlet in fluid communication with the first interstage compressor, a second interstage compressor configured to receive fluid from the vapor outlet of the interstage separation device, a second interstage aftercooler configured to receive fluid from the second interstage compressor and direct the fluid to the high-pressure accumulator, and also includes a simultaneous heat and mass transfer control system that maintains control of the composition and thermal properties of the mixed refrigerant vapor leaving the mixing device vapor outlet, the simultaneous heat and mass transfer control system including at least one of the following: i) a mixing vessel valve having a valve inlet configured to receive fluid from the interstage separation device liquid outlet and the high pressure accumulator liquid outlet, and a valve outlet configured to direct fluid to a third inlet of the mixing device when the mixing vessel valve is open; ii) mixed gas aftercooler; and / or iii) First and / or second interstage aftercoolers.

5. The system according to claim 4, wherein: The mixing device includes a liquid outlet in fluid communication with the low-pressure refrigerant heating passage and / or the intermediate-pressure refrigerant heating passage.

6. The system according to claim 5 further includes a pump having a pump inlet connected to the mixing device liquid outlet fluid and a pump outlet connected to the low-pressure refrigerant heating channel and / or the medium-pressure refrigerant heating channel fluid, and the pump is included in the simultaneous heat and mass transfer control system.

7. The system according to claim 4, wherein: The mixing device comprises a heating coil, and the heating coil is included in the simultaneous heat and mass transfer control system.

8. The system according to claim 1, wherein: The refrigerant purifier is selected from an adsorbent, a freezing device and a distillation column.

9. The system according to claim 1, wherein: The first refrigerant purifier regeneration stream is recycled to the compression system.

10. The system according to claim 9, wherein: The second refrigerant purifier regeneration stream is removed from the liquefaction process by discharging or recycling it upstream of the feed stream cooling passage of the pre-cooling heat exchanger.

11. The system according to claim 1, wherein: The pre-cooling heat exchanger has at least one supplementary refrigerant cooling channel and at least one supplementary refrigerant heating channel.

12. The system according to claim 11, wherein: At least a portion of the supplemental refrigerant is used to provide refrigeration to an external process or system.

13. The system of claim 1, wherein: The feed stream and mixed refrigerant are purified in a combined purifier and the resulting purifier product is separated, with a portion of the purifier product being directed to the feed stream cooling channel and another portion being directed to the compression system.

14. The system of claim 1 further comprising an insulated cold box having an interior and an exterior, wherein: The pre-cooling heat exchanger is located inside the cold box, and the compression system is located outside the cold box.

15. The system according to claim 1 further includes a main refrigerant expansion device operating at a temperature below ambient, the main refrigerant expansion device being configured to receive the main refrigerant from the liquid outlet of the first refrigerant separation device, reduce the temperature and pressure of the received main refrigerant to provide expanded main refrigerant, and guide the expanded main refrigerant to the refrigerant heating channel.

16. A method of liquefying a feed stream comprising hydrogen or helium, comprising the steps of: a. mixing hydrogen or helium refrigerant with at least one additional refrigerant component having a molecular weight higher than hydrogen or helium to form a mixed refrigerant having a molecular weight of at least 6kg / kgmol; b. compressing the mixed refrigerant using a compression system comprising at least one dynamic compressor or dynamic compressor stage; c. separating at least one additional refrigerant component from the hydrogen or helium refrigerant at a temperature of at least 75K to obtain a remaining hydrogen or helium refrigerant; d. Cooling the hydrogen or helium feed stream using the remaining hydrogen or helium refrigerant to produce a liquid hydrogen or helium product from the feed stream comprising hydrogen or helium.

17. The method according to claim 16, wherein: The at least one additional refrigerant component is selected from hydrocarbons containing at least three carbon atoms or neon, partially fluorinated hydrocarbons and fully fluorinated hydrocarbons.

18. The method according to claim 16, wherein: Step c is accomplished using partial condensation and adsorption.

19. The method according to claim 16, wherein: Step c is accomplished using partial condensation and at least two adsorption steps operating at different temperatures, wherein the at least one additional component is removed at a first temperature, impurities in a feed stream comprising hydrogen or helium are removed at a second temperature, the second temperature being a lower temperature than the first temperature, and further comprising a step of discharging the removed impurities.

20. The method of claim 16, further comprising the step of providing refrigeration to a feed stream comprising hydrogen or helium in a heat exchanger using the at least one additional refrigerant component separated in step c.

21. The method of claim 20, further comprising the step of exporting refrigeration provided by the at least one additional refrigerant from the heat exchanger to a second process.

22. The method according to claim 21, wherein: Refrigeration provided by the at least one additional refrigerant is exported from the heat exchanger using a supplemental refrigerant flow at a temperature below ambient.

23. The method according to claim 20, wherein: The step of providing refrigeration to the feed stream comprising hydrogen or helium in a heat exchanger using the at least one additional refrigerant component separated in step c. comprises removing the two-phase stream from the heat exchanger.

24. The method according to claim 16, wherein: The step of cooling the hydrogen or helium feed stream is performed in a heat exchanger located within the cold box, and the step of compressing the mixed refrigerant using a compression system is performed outside the cold box.

25. A system for cooling a cryogenic feed stream containing hydrogen or helium with a mixed refrigerant, comprising: a pre-cooling heat exchanger having a pre-cooling feed flow cooling channel, a low-pressure refrigerant heating channel, a medium-pressure refrigerant heating channel, a first refrigerant cooling channel and a second refrigerant cooling channel; b. a mixed gas compressor configured to receive a mixed refrigerant vapor flow from a low-pressure refrigerant heating passage; c. A mixed gas aftercooler in fluid communication with the mixed gas compressor; d. a mixing device having a first inlet in fluid communication with the mixed gas aftercooler, a second inlet and a mixing device vapor outlet, wherein the second inlet is configured to receive a mixed refrigerant vapor flow from the intermediate pressure refrigerant heating passage; e. a first interstage compressor in fluid communication with the mixing device vapor outlet; f. A first interstage aftercooler in fluid communication with the first interstage compressor; g. a high-pressure accumulator in fluid communication with the first interstage aftercooler and having a high-pressure accumulator vapor outlet and a high-pressure accumulator liquid outlet, wherein the high-pressure accumulator vapor outlet is in fluid communication with the first refrigerant cooling passage, and the high-pressure accumulator liquid outlet is in fluid communication with the medium-pressure refrigerant heating passage; h. a first refrigerant separation device in fluid communication with the first refrigerant cooling passage and having a first refrigerant separation device liquid outlet in fluid communication with the low-pressure refrigerant heating passage and a first refrigerant separation device vapor outlet in fluid communication with the second refrigerant cooling passage; i. A second refrigerant separation device in fluid communication with the second refrigerant cooling passage and having a second refrigerant separation device liquid outlet and a second refrigerant separation device vapor outlet in fluid communication with the low-pressure refrigerant heating passage; j. A refrigerant purifier having a purifier inlet in fluid communication with the second refrigerant separation device vapor outlet and a purifier outlet, wherein the purifier outlet is in fluid communication with the low-pressure refrigerant heating passage and the intermediate-pressure refrigerant heating passage.

26. The system of claim 25, further comprising: k. a liquefaction heat exchanger having a liquefied feed stream cooling passage configured to receive a pre-cooling feed stream from the pre-cooling feed stream cooling passage, a liquefied low-pressure refrigerant heating passage configured to direct refrigerant to a low-pressure refrigerant heating passage of the pre-cooling heat exchanger, a liquefied intermediate-pressure refrigerant heating passage configured to direct refrigerant to an intermediate-pressure refrigerant heating passage of the pre-cooling heat exchanger, a third refrigerant cooling passage in fluid communication with a purifier outlet, and a fourth refrigerant cooling passage configured to receive the first refrigerant portion from the third refrigerant cooling passage; l. A first expansion device configured to receive the second refrigerant portion from the third refrigerant cooling passage and direct the expanded second refrigerant portion to the liquefied medium-pressure refrigerant heating passage; m. A second expansion device configured to receive the cooled first refrigerant portion from the fourth refrigerant cooling passage and direct the expanded cooled first refrigerant portion to the liquefied low-pressure refrigerant heating passage.

27. The system of claim 26, wherein: The liquefaction heat exchanger includes a first liquefaction heat exchanger including the third refrigerant cooling passage and a second liquefaction heat exchanger including the fourth refrigerant cooling passage, and wherein the liquefied feed stream cooling passage, the liquefied low-pressure refrigerant heating passage and the liquefied medium-pressure refrigerant heating passage pass through the first and second liquefaction heat exchangers.

28. The system according to claim 26 further includes a recirculation passage passing through the liquefaction heat exchanger and the pre-cooling heat exchanger, and also includes a product expansion device and a product separation device, the product expansion device being configured to receive a liquid product stream from the liquefaction feed stream cooling passage and directing the resulting expanded product fluid stream to a product separation device, the product separation device having a product separation device vapor outlet and a product separation device liquid outlet fluidly connected to the recirculation passage.

29. The system of claim 25, further comprising a refrigerant expansion device having an inlet in fluid communication with the liquid outlet of the high pressure accumulator and an outlet in fluid communication with the intermediate pressure refrigerant heating passage.

30. The system of claim 25, wherein: The mixing device contains atomizers and / or heating coils.

31. The system of claim 25, wherein: The pre-cooling heat exchanger further includes a first supplementary refrigerant heating channel, a second supplementary refrigerant heating channel and a supplementary refrigerant cooling channel, and further includes: k. a first supplemental refrigerant compressor configured to receive a first supplemental refrigerant vapor flow from a first supplemental refrigerant heating passage; l and the first supplementary refrigerant compressor fluid communication with the first supplementary aftercooler; m. A second supplemental refrigerant compressor in fluid communication with the first supplemental aftercooler and configured to receive a second supplemental refrigerant vapor flow from a second supplemental refrigerant heating passage; n. a second supplemental aftercooler in fluid communication with the second supplemental refrigerant compressor, the second supplemental aftercooler having a second supplemental aftercooler outlet configured to direct fluid to the supplemental refrigerant cooling passage; o a third expansion device having a third expansion device inlet in fluid communication with the supplemental refrigerant cooling passage and a third expansion device outlet in fluid communication with the second supplemental refrigerant heating passage; p. a fourth expansion device having a fourth expansion device inlet in fluid communication with the supplemental refrigerant cooling passage and a fourth expansion device outlet in fluid communication with the first supplemental refrigerant heating passage.

32. The system of claim 25, wherein: The mixed gas compressor and the first inter-stage compressor are multiple dynamic compressors or multiple stages of one dynamic compressor.

33. The system of claim 25, wherein: The mixing device comprises a mixing device liquid outlet, and further comprises: k. an interstage separation device in fluid communication with the first interstage compressor and having an interstage separation device vapor outlet and an interstage separation device liquid outlet; l interstage separation device vapor outlet fluid communication with the second interstage compressor; m. a second interstage aftercooler having an inlet in fluid communication with the second interstage compressor and an outlet in fluid communication with the high pressure accumulator; n. The mixing device liquid outlet, the interstage separation device liquid outlet and the high-pressure accumulator liquid outlet are configured to merge the liquids leaving the mixing device, the interstage separation device and the high-pressure accumulator so that a merged refrigerant liquid flow is formed and directed to the low-pressure refrigerant heating passage and the medium-pressure refrigerant heating passage.

34. The system of claim 33, wherein: The pre-cooling heat exchanger includes a combined refrigerant liquid flow cooling passage, and wherein the combined refrigerant liquid flow is cooled in the combined refrigerant liquid flow cooling passage before being directed to the low-pressure refrigerant heating passage.

35. The system of claim 33, wherein: The mixed gas compressor, the first inter-stage compressor and the second inter-stage compressor are a plurality of dynamic compressors or a plurality of stages of one dynamic compressor.

36. The system of claim 25, wherein: The first refrigerant separation device liquid outlet is also in fluid communication with the intermediate-pressure refrigerant heating passage.

37. The system of claim 36, further comprising: a fifth expansion device configured to receive fluid from the first refrigerant separation device liquid outlet and direct the expanded fluid to the intermediate-pressure refrigerant heating passage; and a sixth expansion device configured to receive fluid from the first refrigerant separation device liquid outlet and direct the expanded fluid to the low-pressure refrigerant heating passage.

38. The system of claim 25, further comprising a refrigerant purifier line in fluid communication with the refrigerant purifier and the mixed gas compressor and configured to recirculate a refrigerant purifier regeneration flow from the refrigerant purifier to the compression system.

39. The system of claim 25, wherein: The pre-cooling heat exchanger also includes a supplementary refrigerant heating channel and a supplementary refrigerant cooling channel, and further includes: k. a supplemental refrigerant compressor configured to receive a first supplemental refrigerant vapor flow from a supplemental refrigerant heating passage; l supplementary aftercooler having an inlet in fluid communication with the supplementary refrigerant compressor and an outlet in fluid communication with the supplementary refrigerant cooling passage; m. A third expansion device having an inlet in fluid communication with the supplemental refrigerant cooling passage and a third expansion device outlet in fluid communication with the supplemental refrigerant heating passage.

40. The system of claim 39, wherein: The mixed gas compressor, the first inter-stage compressor and the supplemental refrigerant compressor are multiple dynamic compressors or multiple stages of a single dynamic compressor.

41. The system of claim 25, wherein: The refrigerant purifier is selected from an adsorbent, a freezing device and a distillation column.

42. The system of claim 25, wherein: The refrigerant purifier is a freezing device.

43. The system of claim 42, further comprising a refrigerant purifier line in fluid communication with the freezing device and the mixed gas compressor and configured to recirculate a refrigerant purifier regeneration flow from the freezing device to the compression system.

44. The system of claim 42, wherein: The refrigerant purifier is a purifier heat exchanger.

45. The system of claim 44, wherein: The purifier heat exchanger is a brazed aluminum heat exchanger or a tubular heat exchanger.

46. ​​The system of claim 44, wherein: The purifier heat exchanger includes a filter configured to capture frozen high molecular weight species.

47. The system of claim 25, wherein: The refrigerant purifier is a first refrigerant purifier having a first refrigerant purifier outlet, and also includes a second refrigerant purifier having a second refrigerant purifier inlet fluidly connected to the first refrigerant purifier outlet, wherein the first refrigerant purifier is configured to remove higher molecular weight impurities having a boiling point greater than 80K, and the second refrigerant purifier is configured to remove lighter molecular weight impurities.

48. The system of claim 47, wherein: The higher molecular weight impurities include hydrocarbons and the lighter molecular weight impurities include nitrogen and / or argon.

49. The system of claim 48, further comprising a refrigerant purifier line in fluid communication with the first refrigerant purifier and the mixed gas compressor and configured to recirculate a refrigerant purifier regeneration stream including the higher molecular weight impurities from the freezing device to the compression system.

50. The system of claim 49, wherein: The second refrigerant purifier is configured to discharge the lighter molecular weight impurities to atmosphere.

51. The system of claim 47, further comprising a purified refrigerant cooling passage in the pre-cooling heat exchanger configured to receive fluid from the first refrigerant purifier outlet and direct cooling fluid to the second refrigerant purifier inlet.

52. The system of claim 25, wherein: The refrigerant purifier is configured to remove nitrogen and / or argon impurities and hydrocarbon impurities from the refrigerant flow.

53. The system of claim 52, further comprising a refrigerant purifier line in fluid communication with the refrigerant purifier and the mixed gas compressor and configured to recirculate a refrigerant purifier regeneration flow containing nitrogen and / or argon impurities and hydrocarbon impurities from the freezing device to the compression system.

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