WO2022187781A1

WO2022187781A1 - Systems and methods for liquefaction of natural gas

Info

Publication number: WO2022187781A1
Application number: PCT/US2022/070574
Authority: WO
Inventors: Maciej Z. LUKAWSKI; Ananda K. NAGAVARAPU
Original assignee: Exxonmobil Upstream Research Company
Priority date: 2021-03-04
Filing date: 2022-02-09
Publication date: 2022-09-09

Abstract

Systems and methods for liquefaction of natural gas. The systems include a feed gas compression and expansion module, which includes a work-producing feed expander and is configured to receive a feed stream, which includes natural gas, and to compress and cool the feed stream to generate a cooled and compressed feed stream. The systems also include a mixed refrigerant compression module, which is configured to receive a warmed and expanded refrigerant stream, which includes a mixed refrigerant, and to compress and cool the warmed and expanded refrigerant stream to generate a compressed refrigerant stream. The systems further includes a cryogenic heat exchange module, which is configured to facilitate thermal energy transfer from the natural gas to the mixed refrigerant. The systems also include a mixed refrigerant expansion module. The methods include methods of operating the systems.

Description

SYSTEMS AND METHODS FOR LIQUEFACTION OF NATURAL GAS

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the priority benefit of United States Provisional Patent

Application No. 63/156573, filed March 4, 2021, entitled SYSTEMS AND METHODS FOR LIQUEFACTION OF NATURAL GAS, the entirety of which is incorporated by reference herein. FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to systems and methods for liquefaction of natural gas.

BACKGROUND OF THE DISCLOSURE

[0003] Natural gas is an important natural resource for which significant reserves exist. Natural gas generally is produced in the gaseous state and liquefied to facilitate more efficient storage and/or transport over long distances. To enable liquefaction of the produced natural gas, a variety of liquefaction technologies exist. Single Mixed Refrigerant (SMR) liquefaction technologies are an example of technologies that historically have been utilized to liquefy natural gas. While relatively simple and effective, conventional SMR technologies suffer from several drawbacks, such as, lower thermodynamic efficiency, when compared to more complex liquefaction technologies such as the dual mixed refrigerant (DMR) technologies. In addition, the overall LNG throughput is typically constrained, driven by limitation of approach temperature on one end of the main cryogenic heat exchanger, which results in high log-mean- temperature-difference (LMTD) limitations between the hot and cold streams in the main cryogenic heat exchanger utilized within the SMR technologies. This, and other process specifics, such as interconnecting piping sizes, make it challenging to significantly scale conventional SMR technologies for larger throughputs. Thus, there exists a need for improved systems and methods for liquefaction of natural gas.

SUMMARY OF THE DISCLOSURE

[0004] Systems and methods for liquefaction of natural gas. The systems include a feed gas compression and expansion module and a mixed refrigerant compression module. The feed gas compression and expansion module includes a work-producing feed expander and is configured to receive a feed stream that includes natural gas and to compress and cool the feed stream to generate a cooled and compressed feed stream. The mixed refrigerant compression module is configured to receive a warmed and expanded refrigerant stream that includes a mixed refrigerant and to compress and cool the warmed and expanded refrigerant stream to generate a compressed refrigerant stream.

[0005] The systems further includes a cryogenic heat exchange module, which is configured to receive the cooled and compressed feed stream and the compressed refrigerant stream, to facilitate thermal energy transfer from the natural gas to the mixed refrigerant. The cryogenic heat exchange module includes a natural-gas-receiving region, which is configured to receive the cooled and compressed feed stream and to discharge an at least partially liquefied outlet stream. The cryogenic heat exchange module also includes a first mixed-refrigerant receiving region, which is configured to receive the compressed refrigerant stream and to discharge a cooled and compressed refrigerant stream. The cryogenic heat exchange module further includes a second mixed-refrigerant-receiving region, which is configured to receive an expanded refrigerant stream and to discharge the warmed and expanded refrigerant stream. [0006] The systems also include a mixed refrigerant expansion module, which is configured to receive the cooled and compressed refrigerant stream from the cryogenic heat exchange module and to expand the cooled and compressed refrigerant stream to generate the expanded refrigerant stream. The mixed refrigerant expansion module includes a work- producing mixed refrigerant hydraulic turbine.

[0007] The methods include methods of operating the systems to liquefy natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a schematic illustration of examples of systems configured to liquefy natural gas, according to the present disclosure.

[0009] Fig. 2 is a schematic illustration of examples of feed gas compression and expansion modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0010] Fig. 3 is a schematic illustration of examples of mixed refrigerant compression modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0011] Fig. 4 is a schematic illustration of examples of cryogenic heat exchange modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure. [0012] Fig. 5 is a schematic illustration of examples of cryogenic heat exchange modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0013] Fig. 6 is a schematic illustration of examples of cryogenic heat exchange modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0014] Fig. 7 is a schematic illustration of examples of mixed refrigerant expansion modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0015] Fig. 8 is a schematic illustration of examples of heavy hydrocarbon recovery modules that may be utilized with systems configured to liquefy natural gas, according to the present disclosure.

[0016] Fig. 9 is a flowchart depicting examples of methods of liquefying natural gas, according to the present disclosure.

DETAILED DESCRIPTION AND BEST MODE OF THE DISCLOSURE [0017] Figs. 1-9 provide examples of systems 10 configured to liquefy natural gas, of components of systems 10, and/or of methods 800 of liquefying natural gas, according to the present disclosure. Elements that serve a similar, or at least substantially similar, purpose are labeled with like numbers in each of Figs. 1-9, and these elements may not be discussed in detail herein with reference to each of Figs. 1-9. Similarly, all elements may not be labeled in each of Figs. 1-9, but reference numerals associated therewith may be utilized herein for consistency. Elements, components, and/or features that are discussed herein with reference to one or more of Figs. 1-9 may be included in and/or utilized with any of Figs. 1-9 without departing from the scope of the present disclosure.

[0018] In general, elements that are likely to be included in a particular embodiment are illustrated in solid lines, while elements that are optional are illustrated in dashed lines. However, elements that are shown in solid lines may not be essential to all embodiments and, in some embodiments, may be omitted without departing from the scope of the present disclosure.

[0019] Fig. 1 is a schematic illustration of examples of systems 10 configured to liquefy natural gas 110, according to the present disclosure. As illustrated in solid lines in Fig. 1, system 10 may include a feed gas compression and expansion module 100, and system 10 includes a mixed refrigerant compression module 200, a cryogenic heat exchange module 300, and a mixed refrigerant expansion module 400. It is to be appreciated that systems 10 may be operated using only modules 200 and 300; or alternatively may be operated using only modules 100, 200, and 300; or alternatively may be operated using only modules 200, 300, and 400; or yet alternatively may be operated using each of modules 100, 200, 300, and 400.

[0020] In examples of systems 10 that include feed gas compression and expansion module

100, the feed gas compression and expansion module may be configured to receive a feed stream 105, which includes natural gas 110. Feed gas compression and expansion module 100 also is configured to compress and cool the feed stream to generate a cooled and compressed feed stream 115, which also includes natural gas 110. Feed gas compression and expansion module 100 may include a work-producing feed expander 120, which the feed gas compression and expansion module utilizes to generate the cooled and compressed feed stream from the feed stream. Work-producing feed expander 120 also may be referred to herein as, and/or may be, a work-producing feed expansion device 120.

[0021] Mixed refrigerant compression module 200 is configured to receive a warmed and expanded refrigerant stream 202, which includes a mixed refrigerant 204. Mixed refrigerant compression module 200 further is configured to compress and cool the warmed and expanded refrigerant stream to generate a compressed refrigerant stream 206, which also includes mixed refrigerant 204.

[0022] Cryogenic heat exchange module 300 is configured to facilitate thermal energy transfer from natural gas 110 to mixed refrigerant 204, such as to permit and/or to facilitate cooling and/or liquefaction of the natural gas. Cryogenic heat exchange module 300 includes a natural-gas-receiving region 306. Natural-gas-receiving region 306 is configured to receive cooled and compressed feed stream 115, when present, and/or to receive feed stream 105. Natural-gas-receiving region 306 also is configured to discharge an at least partially liquefied outlet stream 312, which includes liquefied natural gas 110. Cryogenic heat exchange module 300 also includes a first mixed-refrigerant-receiving region 330, which is configured to receive compressed refrigerant stream 206 and to discharge a cooled and compressed refrigerant stream 352. Cryogenic heat exchange module 300 further includes a second mixed-refrigerant receiving region 360, which is configured to receive an expanded refrigerant stream 374 and to discharge warmed and expanded refrigerant stream 202. Second mixed-refrigerant- receiving-region 360 is in thermal communication with both natural-gas-receiving region 306 and first mixed-refrigerant-receiving region 330.

[0023] Mixed refrigerant expansion module 400 is configured to receive cooled and compressed refrigerant stream 352 from cryogenic heat exchange module 300 and/or from first mixed-refrigerant-receiving region 330 thereof. Mixed refrigerant expansion module 400 also is configured to expand cooled and compressed refrigerant stream 352 to generate expanded refrigerant stream 374. Mixed refrigerant expansion module 400 includes a work-producing mixed-refrigerant hydraulic turbine 405, which the mixed refrigerant expansion module utilizes to generate the expanded refrigerant stream from the cooled and compressed refrigerant stream. Work-producing mixed-refrigerant hydraulic turbine 405 also may be referred to herein as, and/or may be, a work-producing mixed-refrigerant expansion device 405 and/or as a work-producing mixed-refrigerant expander 405.

[0024] During operation of system 10, and as discussed in more detail herein with reference to methods 800 of Fig. 9, mixed refrigerant 204 may be circulated within a refrigerant loop, or refrigerant cycle, that includes and/or utilizes mixed refrigerant compression module 200, cryogenic heat exchange module 300, and mixed refrigerant expansion module 400. Concurrently, natural gas 110 flows from feed gas compression and expansion module 100 through cryogenic heat exchange module 300, thereby producing and/or generating at least partially liquefied outlet stream 312 via thermal energy transfer from the natural gas to the mixed refrigerant within the cryogenic heat exchange module.

[0025] As discussed, feed gas compression and expansion module 100 includes work- producing feed expander 120, and mixed refrigerant expansion module 400 includes work- producing mixed-refrigerant hydraulic turbine 405. The presence of feed gas compression and expansion module 100, including work-producing feed expander 120, may cause natural gas

110 to enter cryogenic heat exchange module 300 at a lower temperature and/or at a higher pressure when compared to conventional single mixed refrigerant (SMR) systems that do not include and/or utilize the feed gas compression and expansion module. This has several beneficial effects when compared to the conventional SMR systems.

[0026] As an example, throughput of natural gas through cryogenic heat exchange module 300 may be increased because a fraction of the cooling duty is shifted to the feed gas compression and expansion module. As another example, the increase in pressure of the natural gas may result in a better match between composite heating and cooling curves within the cryogenic heat exchange module and/or may permit the temperature of the at least partially liquefied outlet stream to be increased. As yet another example, a composition of the mixed refrigerant may be shifted to generally smaller hydrocarbon molecules, which may permit mixed refrigerant makeup from hydrocarbon reserves that provide a leaner feed gas composition and/or may permit mixed refrigerant compression module only to utilize single compression stage 208 under some conditions.

[0027] As also discussed, mixed refrigerant expansion module 400 includes work- producing mixed-refrigerant hydraulic turbine 405. The presence of mixed refrigerant expansion module 400, including work-producing mixed-refrigerant hydraulic turbine 405, may provide several beneficial effects when compared to conventional SMR systems. As an example, the presence of work-producing mixed-refrigerant hydraulic turbine 405 may produce a larger temperature drop within the mixed refrigerant upon expansion thereof. This increase in temperature drop may cause a pinch point within cryogenic heat exchange module 300 to shift from the cold end of the cryogenic heat exchange module toward the middle of the cryogenic heat exchange module. The combination of this shift in pinch point and the lower natural gas inlet temperature and higher natural gas inlet pressure to cryogenic heat exchange module 300, which is driven by the presence of work-producing feed expander 120 within feed gas compression and expansion module 100, may cause an improved temperature match in temperature-enthalpy curves within cryogenic heat exchange module 300 and/or may lower log-mean-temperature-difference constraints when compared to conventional SMR systems. This may permit and/or facilitate additional efficiency and throughput gains through increases in the size and/or heat transfer area of the cryogenic heat exchange module that are typically not feasible or impactful for conventional SMR technologies. Additionally or alternatively, and as discussed in more detail herein, cryogenic heat exchange module 300 may be designed with a buffer region that permits heat exchange between high-pressure and low-pressure mixed refrigerant streams without thermal interaction with the natural gas. [0028] As another example, mixed refrigerant 204 within systems 10 according to the present disclosure may have a lower nitrogen gas content when compared to conventional SMR systems which may permit higher thermodynamic efficiencies. As yet another example, systems 10 according to the present disclosure may benefit from improved efficiency due to power generation from work-producing feed expander 120 and/or work-producing mixed- refrigerant hydraulic turbine 405.

[0029] The above-described benefits may have synergistic effects that produce disproportionately large, and unexpected, improvements in overall system performance. As an example, an 18% increase in throughput in combination with a 9% increase in energy efficiency has been observed. [0030] As discussed in more detail herein, and in some examples, systems 10 may include a heavy hydrocarbon recovery module 500. Heavy hydrocarbon recovery module 500, when present, may be separate, distinct, and/or spaced-apart from cryogenic heat exchange module 300. Stated another way, systems 10 may described as including and/or utilizing non- integrated heavy hydrocarbon recovery, in the form of heavy hydrocarbon recovery module 500.

[0031] Heavy hydrocarbon recovery module 500 may be configured to receive and to separate a raw feed stream 505, which includes natural gas 110, into a heavy hydrocarbon stream 510 and feed stream 105. Heavy hydrocarbon stream 510 may include a greater fraction of relatively heavier hydrocarbons, such as a greater fraction of ethane, propane, butane, and/or pentane, from raw feed stream 505 when compared to feed stream 105. Conversely, feed stream 105 may include a greater fraction of relatively lighter hydrocarbons, such as a greater fraction of methane, ethane, and/or propane, from raw feed stream 505 when compared to heavy hydrocarbon stream 510. Stated another way, an average molecular weight of hydrocarbons within heavy hydrocarbon stream 510 may be greater than an average molecular weight of hydrocarbons within feed stream 105.

[0032] As illustrated in dashed lines in Fig. 1, and discussed in more detail herein, heavy hydrocarbon stream 510 may be provided to mixed refrigerant compression module 200 as a mixed refrigerant make-up stream 252. As also illustrated in dashed lines in Fig. 1, and discussed in more detail herein, a slip stream 525 of cooled and compressed feed stream 115 may be provided to heavy hydrocarbon recovery module 500, such as to generate reflux within a separation column 515 of the heavy hydrocarbon recovery module.

[0033] As illustrated in dashed lines in Fig. 1, and in some examples, systems 10 may include and/or utilize a refrigeration module 600. Refrigeration module 600, when present, may be configured to further cool cooled and compressed feed stream 115 prior to supply of the cooled and compressed feed stream to cryogenic heat exchange module 300. Examples of refrigeration module 600 include a direct expansion refrigeration module and/or an evaporative refrigeration module.

[0034] As illustrated in dashed lines in Fig. 1, and in some examples, systems 10 may include and/or utilize an outlet stream expansion module 700. Outlet stream expansion module 700, when present, may be configured to receive, and to expand, at least partially liquefied outlet stream 312 to produce and/or generate an expanded outlet stream 705. In some examples, outlet stream expansion module 700 may include a work-producing outlet stream expander 710, which may be configured to receive and expand the at least partially liquefied outlet stream to generate the expanded outlet stream and outlet stream expansion work. In some examples, outlet stream expansion module 700 further may include an outlet module generator 715, which may be configured to be powered by the work-producing outlet stream expander, such as by the outlet stream expansion work, and/or to generate an outlet stream electric current 720. Examples of work-producing outlet stream expander 710 include a work- producing outlet stream turboexpander and/or a work-producing outlet stream hydraulic turbine.

[0035] In some examples, outlet stream expansion module 700 may include an outlet stream expansion valve 725, which may be configured to receive and expand the at least partially liquefied outlet stream to generate the expanded outlet stream. An example of the outlet stream expansion valve includes an outlet stream Joule-Thomson valve. [0036] As discussed, the composition of mixed refrigerant 204 may differ from a composition of a conventional mixed refrigerant that may be utilized within a conventional SMR system. As also discussed, this variation from the composition of the conventional mixed refrigerant may include a shift to relatively lighter hydrocarbons, a lower concentration of relatively heavier hydrocarbons, and/or a lower concentration of nitrogen gas, which may provide certain benefits in terms of the overall performance of systems 10 and/or the ability to utilize mixed refrigerant make-up streams 252, which may be generated by hydrocarbon reserves that include relatively lower concentrations of relatively heavier hydrocarbons, such as pentane.

[0037] As examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 6 mole %, at least 6.5 mole %, at least 7 mole %, at least 7.5 mole %, at least 8 mole %, at least 8.5 mole %, at least 9 mole %, at least 9.5 mole %, at least 10 mole %, at least 10.5 mole %, at least 11 mole %, or at least 11.5 mole % nitrogen gas. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 14 mole %, at most 13.5 mole %, at most 13 mole %, at most 12.5 mole %, at most 12 mole %, at most 11.5 mole %, or at most 11 mole % nitrogen gas.

[0038] As additional examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 25 mole %, at least 25.5 mole %, at least 26 mole %, at least 26.5 mole %, at least 27 mole %, at least 27.5 mole %, at least 28 mole %, at least 28.5 mole %, at least

29 mole %, at least 29.5 mole %, at least 30 mole %, at least 30.5 mole %, or at least 31 mole % methane. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 35 mole %, at most 34.5 mole %, at most 34 mole %, at most 33.5 mole %, at most 33 mole %, at most 32.5 mole %, at most 32 mole %, at most 31.5 mole %, at most 31 mole %, at most 30.5 mole %, at most 30 mole %, at most 29.5 mole %, or at most 29 mole % methane.

[0039] As additional examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 25 mole %, at least 25.5 mole %, at least 26 mole %, at least 26.5 mole %, at least 27 mole %, at least 27.5 mole %, at least 28 mole %, at least 28.5 mole %, at least 29 mole %, at least 29.5 mole %, at least 30 mole %, at least 30.5 mole %, or at least 31 mole % ethane. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 35 mole %, at most 34.5 mole %, at most 34 mole %, at most 33.5 mole %, at most 33 mole %, at most 32.5 mole %, at most 32 mole %, at most 31.5 mole

%, at most 31 mole %, at most 30.5 mole %, at most 30 mole %, at most 29.5 mole %, or at most 29 mole % ethane.

[0040] As additional examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 6 mole %, at least 6.5 mole %, at least 7 mole %, at least 7.5 mole %, at least 8 mole %, at least 8.5 mole %, at least 9 mole %, at least 9.5 mole %, or at least 10 mole % propane. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 14 mole %, at most 13.5 mole %, at most 13 mole %, at most

12.5 mole %, at most 12 mole %, at most 11.5 mole %, at most 11 mole %, at most 10.5 mole %, at most 10 mole %, at most 9.5 mole %, at most 9 mole %, at most 8.5 mole %, at most 8 mole %, at most 7.5 mole %, or at most 7 mole % propane.

[0041] As additional examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 3 mole %, at least 3.5 mole %, at least 4 mole %, at least 4.5 mole %, at least 5 mole %, at least 5.5 mole %, at least 6 mole %, at least 6.5 mole %, at least 7 mole %, at least 7.5 mole %, at least 8 mole %, at least 8.5 mole %, at least 9 mole %, at least 9.5 mole %, or at least 10 mole % butane. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 10 mole %, at most 9.5 mole %, at most 9 mole %, at most 8.5 mole %, at most 8 mole %, at most 7.5 mole %, at most 7 mole %, at most

6.5 mole %, or at most 6 mole % butane. [0042] As additional examples, mixed refrigerant 204 may include, consist of, or consist essentially of at least 9 mole %, at least 9.5 mole %, at least 10 mole %, at least 10.5 mole %, at least 11 mole %, at least 11.5 mole %, at least 12 mole %, at least 12.5 mole %, or at least 13 mole % pentane. Additionally or alternatively, mixed refrigerant 204 may include, consist of, or consist essentially of at most 16 mole %, at most 15.5 mole %, at most 15 mole %, at most 14.5 mole %, at most 14 mole %, at most 13.5 mole %, at most 13 mole %, at most 12.5 mole %, at most 12 mole %, at most 11.5 mole %, at most 11 mole %, at most 10.5 mole %, or at most 10 mole % pentane

[0043] In some examples, and as illustrated in dashed lines in Fig. 1, mixed refrigerant compression module 200, cryogenic heat exchange module 300, and mixed refrigerant expansion module 400 together may define a natural gas liquefaction module 190. In some such examples, system 10 may include a plurality of natural gas liquefaction modules 190 and feed gas compression and expansion modules 100, or a single feed gas compression and expansion module 100, may be configured to provide cooled and compressed feed stream 115 to the plurality of natural gas liquefaction modules 190. Examples of the plurality of natural gas liquefaction modules include at least 2, at least 4, at least 6, at least 8, at least 10, at most 20, at most 18, at most 16, at most 14, at most 12, and/or at most 10 natural gas liquefaction modules 190.

[0044] Fig. 2 is a schematic illustration of examples of a feed gas compression and expansion modules 100 that may be utilized with systems 10 configured to liquefy natural gas

110, according to the present disclosure. Fig. 2 may include and/or be a more detailed illustration of examples of feed gas compression and expansion module 100 that is illustrated in Fig. 1, and any of the structures, functions, and/or features of feed gas compression and expansion modules 100 that are discussed herein with reference to Fig. 2 may be included in and/or utilized with systems 10 and/or feed gas compression and expansion module 100 of Fig. 1 without departing from the scope of the present disclosure. Similarly, any of the structures, functions, and/or features of systems 10 and/or of feed gas compression and expansion module 100 that are discussed herein with reference to Fig. 1 may be included in and/or utilized with feed gas compression and expansion modules 100 of Fig. 2 without departing from the scope of the present disclosure.

[0045] As illustrated in Fig. 2, feed gas compression and expansion module 100 may include a first feed compressor 130, a second feed compressor 150, and work-producing feed expander 120. First feed compressor 130 may be configured to receive feed stream 105 and to compress the feed stream to generate a partially compressed feed stream 135. Second feed compressor 150 may be configured to receive partially compressed feed stream 135 and to compress the partially compressed feed stream to generate a compressed feed stream 140. Work-producing feed expander 120 may be configured to receive compressed feed stream 140 and to expand and cool the compressed feed stream to generate cooled and compressed feed stream 115 and feed expansion work 145. Examples of first feed compressor 130 and/or of second feed compressor 140 include reciprocating compressors and/or centrifugal compressors. An example of work-producing feed expander 120 includes a work-producing feed turboexpander. [0046] In some examples, and as illustrated in dashed lines in Fig. 2, feed gas compression and expansion module 100 may include a first feed cooler 155 and/or a second feed cooler 160. First feed cooler 155, when present, may be configured to cool partially compressed feed stream 135 prior to supply of the partially compressed feed stream to second feed compressor 150. Similarly, second feed cooler 160, when present, may be configured to cool compressed feed stream 140 prior to supply of the compressed feed stream to work-producing feed expander 120. Examples of first feed cooler 155 and/or of second feed cooler 160 include evaporative coolers, air-cooled condensers, liquid-cooled condensers, and/or direct expansion refrigeration systems.

[0047] In some examples, and as also illustrated in dashed lines in Fig. 2, feed gas compression and expansion module 100 may include a first linkage 162 and/or a second linkage 165. First linkage 162, when present, may be configured to convey at least a first fraction of feed expansion work 145 from work-producing feed expander 120 to first feed compressor 130 to at least partially power the first feed compressor. Additionally or alternatively, first feed compressor 130 may be powered by a feed power source 170, such as a feed compressor electric motor, a feed compressor steam turbine, and/or a feed compressor gas turbine. Similarly, second linkage 165, when present, may be configured to convey at least a second fraction of feed expansion work 145 from work-producing feed expander 120 to second feed compressor 150 to at least partially power the second feed compressor.

Additionally or alternatively, second feed compressor may be powered by feed power source 170. Examples of first linkage 162 and/or of second linkage 165 include a mechanical linkage, a hydraulic linkage, and/or a pneumatic linkage. In some examples, a feed generator 180 may be configured to receive at least a generator fraction of feed expansion work 145 and may generate a feed electrical output from the feed expansion work.

[0048] In some examples, and as illustrated in dashed lines in Fig. 2, feed gas compression and expansion module 100 may include a feed gas bypass 175, or even a plurality of feed gas bypasses 175. Feed gas bypass 175, when present, may be configured to selectively bypass, or to permit natural gas 110 to selectively bypass, one or more components of feed gas compression and expansion module 100, such as first feed compressor 130, second feed compressor 150, and/or work-producing feed expander 120. This selective bypassing may, for example, be responsive to failure of the one or more components of the feed gas compression and expansion module. Such a configuration may permit and/or facilitate operation of system

10 and/or of feed gas compression and expansion module 100 despite failure of the one or more components of the feed gas compression and expansion module. Examples of feed gas bypass 175 include any suitable tube, pipe, fluid conduit, valve, electronically actuated valve, manually actuated valve, and/or pressure relief valve. [0049] Fig. 3 is a schematic illustration of examples of mixed refrigerant compression modules 200 that may be utilized with systems 10 configured to liquefy natural gas 110, according to the present disclosure. Fig. 3 may include and/or be a more detailed illustration of examples of mixed refrigerant compression module 200 that is illustrated in Fig. 1, and any of the structures, functions, and/or features of mixed refrigerant compression modules 200 that are discussed herein with reference to Fig. 3 may be included in and/or utilized with systems

10 and/or mixed refrigerant compression module 200 of Fig. 1 without departing from the scope of the present disclosure. Similarly, any of the structures, functions, and/or features of systems 10 and/or of mixed refrigerant compression module 200 that are discussed herein with reference to Fig. 1 may be included in and/or utilized with mixed refrigerant compression modules 200 of Fig. 3 without departing from the scope of the present disclosure.

[0050] As discussed, mixed refrigerant compression modules 200 may be configured to receive warmed and expanded refrigerant stream 202 and to compress and cool the warmed and expanded refrigerant stream to produce and/or generate compressed refrigerant stream 206. As also discussed, mixed refrigerant compression module 200 may be configured to receive a mixed refrigerant make-up stream 252, such as via a mixed refrigerant make-up inlet 250 thereof. The mixed refrigerant make-up stream may be produced, generated, and/or provided by heavy hydrocarbon recovery module 500, when present, or from another suitable source. The mixed refrigerant make-up stream may be combined with mixed refrigerant 204 within and/or proximate mixed refrigerant compression module 200.

[0051] In some examples, and as discussed, mixed refrigerant compression modules 200 may include and/or utilize a single, or only a single, compression stage 208, as illustrated in solid lines in Fig. 2. In some examples, mixed refrigerant compression modules 200 may include and/or utilize a plurality of compression stages 208.

[0052] As illustrated in solid lines in Fig. 3, mixed refrigerant compression module 200 may include a mixed refrigerant liquid-vapor separator 210, a mixed refrigerant liquid pump 216, and a mixed refrigerant vapor compressor 220. Mixed refrigerant liquid-vapor separator 210 may be configured to receive warmed and expanded refrigerant stream 202 and to separate the warmed and expanded refrigerant stream into a warmed and expanded liquid refrigerant stream 212 and a warmed and expanded vapor refrigerant stream 214. Mixed refrigerant liquid pump 216 may be configured to receive and compress warmed and expanded liquid refrigerant stream 212 to produce and/or generate a compressed liquid refrigerant stream 218. Mixed refrigerant vapor compressor 220 may be powered by a compression module power source 260 and/or may be configured to receive and compress warmed and expanded vapor refrigerant stream 214 to produce and/or generate a compressed vapor refrigerant stream 222. In examples of mixed refrigerant compression modules 200 that include the single, or only the single, compression stage 208, the mixed refrigerant compression module may be configured to discharge a combination 224 of compressed liquid refrigerant stream 218 and compressed vapor refrigerant stream 222 as compressed refrigerant stream 206. Examples of compression module power source 260 include a compression module electric motor, a compression module steam turbine, and/or a compression module gas turbine. [0053] In examples of mixed refrigerant compression module 200 that include the plurality of compression stages 208, mixed refrigerant liquid-vapor separator 210 may be referred to herein as, and/or may be, a first mixed refrigerant liquid-vapor separator 210. Similarly, mixed refrigerant liquid pump 216 may be referred to herein as, and/or may be, a first mixed refrigerant liquid pump 216, and compressed liquid refrigerant stream 218 may be referred to herein as, and/ormaybe, a first partially compressed liquid refrigerant stream 218. In addition, mixed refrigerant vapor compressor 220 may be referred to herein as, and/or may be, a first mixed refrigerant vapor compressor 220, and compressed vapor refrigerant stream 222 may be referred to herein as, and/or may be, a first partially compressed vapor refrigerant stream. 222. [0054] In such a configuration, and as illustrated in dashed lines in Fig. 3, mixed refrigerant compression module 200 also may include a second mixed refrigerant liquid-vapor separator 226, a second mixed refrigerant liquid pump 232, and a second mixed refrigerant vapor compressor 236. Second mixed refrigerant liquid-vapor separator 226 may be configured to receive and separate first partially compressed liquid refrigerant stream 218 and first partially compressed vapor refrigerant stream 222 to generate a second partially compressed liquid refrigerant stream 228 and second partially compressed vapor refrigerant stream 230. Second mixed refrigerant liquid pump 232 may be configured to receive and compress second partially compressed liquid refrigerant stream 228 to generate a compressed liquid refrigerant stream 234. Second mixed refrigerant vapor compressor 236 may be powered by the same, or by a different, compression module power source 260 and/or may be configured to receive and compress second partially compressed vapor refrigerant stream 230 to generate a compressed vapor refrigerant stream 238. In examples of mixed refrigerant compression modules 200 that include the plurality of compression stages 208, the mixed refrigerant compression module may be configured to discharge a combination 240 of compressed liquid refrigerant stream 234 and compressed vapor refrigerant stream 238 as compressed refrigerant stream 206.

[0055] As illustrated in dashed lines in Fig. 3, mixed refrigerant compression module 200 may include one or more coolers, such as a partially compressed vapor cooler 242, a compressed liquid refrigerant cooler 244, a compressed vapor refrigerant cooler 246, and/or compressed refrigerant stream cooler 248. Partially compressed vapor cooler 242, when present, may be configured to cool first partially compressed vapor refrigerant stream 222, such as prior to supply of the first partially compressed vapor refrigerant stream to second mixed refrigerant liquid-vapor separator. Compressed liquid refrigerant cooler 244, when present, may be configured to cool compressed liquid refrigerant stream 218/234 prior to combination of the compressed liquid refrigerant stream with compressed vapor refrigerant stream 222/246 and/or prior to discharge of the compressed liquid refrigerant stream from the mixed refrigerant compression module. Compressed vapor refrigerant cooler 246, when present, may be configured to cool compressed vapor refrigerant stream 222/238 prior to combination of the compressed vapor refrigerant stream with compressed liquid refrigerant stream 218/234 and/or prior to discharge of the compressed vapor refrigerant stream from the mixed refrigerant compression module. Compressed refrigerant stream cooler 248, when present, may be configured to cool compressed refrigerant stream 206 prior to discharge of the compressed refrigerant stream from the mixed refrigerant compression module.

[0056] Figs. 4-6 are schematic illustrations of examples of cryogenic heat exchange modules 300 that may be utilized with systems 10 configured to liquefy natural gas 110, according to the present disclosure. Figs. 4-6 may include and/or be more detailed illustrations of examples of cryogenic heat exchange modules 300 that are illustrated in Fig. 1, and any of the structures, functions, and/or features of cryogenic heat exchange module 300 that are discussed herein with reference to Figs. 4-6 may be included in and/or utilized with systems 10 and/or cryogenic heat exchange modules 300 of Fig. 1 without departing from the scope of the present disclosure. Similarly, any of the structures, functions, and/or features of systems 10 and/or of cryogenic heat exchange modules 300 that are discussed herein with reference to Fig. 1 may be included in and/or utilized with cryogenic heat exchange modules 300 of Fig. 4- 6 without departing from the scope of the present disclosure. Examples of cryogenic heat exchange modules 300 include a brazed aluminum heat exchanger and/or a wound coil heat exchanger.

[0057] Referring generally to Figs. 1 and 4-6, compressed refrigerant stream 206 is heated, within first mixed-refrigerant-receiving region 330 of cryogenic heat exchange module 300, via thermal exchange with natural-gas-receiving region 306. In addition, compressed refrigerant stream 206 also is cooled, within first mixed-refrigerant-receiving region 330, via thermal exchange with second mixed-refrigerant-receiving region 360. This combination of heating and cooling of the compressed refrigerant stream produces and/or generates cooled and compressed refrigerant stream 352. Similarly, expanded refrigerant stream 374 is heated, within second mixed-refrigerant-receiving region 360, via thermal exchange with both natural- gas-receiving region 306 and first mixed-refrigerant-receiving region 330, to produce and/or generate warmed and expanded refrigerant stream 202.

[0058] Natural-gas-receiving region 306 may include any suitable structure that may be adapted, configured, designed, and/or constructed to contain and/or to house natural gas 110, to fluidly isolate natural gas 110 from mixed refrigerant 204, to exchange thermal energy with first mixed-refrigerant-receiving region 330, to exchange thermal energy with second mixed- refrigerant-receiving region 360, and/or to generate at least partially liquefied outlet stream 312 from cooled and compressed feed stream 115. In some examples, cooled and compressed feed stream 115 may be cooled, such as within natural-gas-receiving region 306, via thermal exchange with first mixed-refrigerant-receiving region 330, and/or via thermal exchange with second mixed-refrigerant-receiving region 360, to produce and/or generate at least partially liquefied outlet stream 312. In some examples, natural-gas-receiving region 306 may extend between a natural gas inlet 308, which is configured to receive cooled and compressed feed stream 115, and a natural gas outlet 310, which is configured to discharge at least partially liquefied outlet stream 312.

[0059] In some examples, natural-gas-receiving region 306 may be free of a heavy hydrocarbon recovery region. Stated another way, and in some such examples, natural-gas- receiving region 306 may include only one inlet, namely, natural gas inlet 308, and/or may include only one outlet, namely, natural gas outlet 310. Stated yet another way, and in some such examples, natural-gas-receiving region 306 may be free of a heavy hydrocarbon outlet, which might be utilized to remove heavy hydrocarbons from natural gas 110. Stated still another way, and as discussed, systems 10 may utilize heavy hydrocarbon recovery module 500 or another type of non-integrated heavy hydrocarbon recovery module, when present, to remove heavy hydrocarbons from the natural gas.

[0060] As illustrated in solid lines in Figs. 4-6, and in some examples, cryogenic heat exchange module 300 may include a buffer region 388. Buffer region 388, when present, may include and/or be a region within which natural-gas-receiving region 306 is thermally isolated from first mixed-refrigerant-receiving region 330 and/or from second mixed-refrigerant receiving region 360. However, first mixed-refrigerant-receiving region 330 may be in thermal communication with second mixed-refrigerant-receiving region 360 within the buffer region. Stated another way, buffer region 388 may include and/or be a region of cryogenic heat exchange module 300 within which first mixed-refrigerant-receiving region 330 and second mixed-refrigerant-receiving region 360 exchange thermal energy with one another but do not exchange thermal energy with natural-gas-receiving region 306.

[0061] Buffer region 388, when present, may extend along a fraction of a length 302 of cryogenic heat exchange module 300 and/or of a portion of the cryogenic heat exchange module where first mixed-refrigerant-receiving region 330 and second mixed-refrigerant receiving region 360 exchange thermal energy with one another. Examples of the fraction of length 302 include at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at most 15%, at most 14%, at most 13%, at most 12%, at most 11%, or at most 10% of length 302. As illustrated in dashed lines in Figs. 4-6, and in some examples, natural-gas-receiving region 306 may be in thermal communication with first-mixed- refrigerant-receiving region 330 and/or with second mixed-refrigerant-receiving region 360 along an entirety of length 302 of cryogenic heat exchange module 300. [0062] Returning to Fig. 1, and in some examples, systems 10 optionally may include a compressed refrigerant liquid-vapor separator 314. Compressed refrigerant liquid-vapor separator 314, when present, may be configured to receive and separate compressed refrigerant stream 206 into a liquid compressed refrigerant stream 316 and a vapor compressed refrigerant stream 318. In some examples, and as illustrated in dashed lines in Fig. 1, compressed refrigerant stream 206 may include and/or be a mixture of liquid compressed refrigerant stream 316 and vapor compressed refrigerant stream 318 upon supply to cryogenic heat exchange module 300. In other examples, and as illustrated in dotted lines in Fig. 1 and discussed in more detail herein, liquid compressed refrigerant stream 316 and vapor compressed refrigerant stream 318 separately may be provided to cryogenic heat exchange module 300.

[0063] Cryogenic heat exchange module 300 may include and/or may be configured for a plurality of fluidic passes 304 therethrough. An example of cryogenic heat exchange module 300 that includes three fluidic passes 304 is illustrated in Fig. 4. An example of cryogenic heat exchange module 300 that includes four fluidic passes 304 is illustrated in Fig.

5. An example of cryogenic heat exchange module 300 that includes five fluid passes 304 is illustrated in Fig. 6. Variations in the number of fluid passes 304 may permit and/or facilitate improved performance and/or efficiency of cryogenic heat exchange modules 300.

[0064] Turning to Fig. 4, and with reference to Figs. 5-6, a first fluidic pass 304 may be defined by natural-gas-receiving region 306, a second fluidic pass 304 may be defined by first mixed-refrigerant-receiving region 330, and a third fluidic pass 304 may be defined by second mixed-refrigerant-receiving region 360. In such configurations, first mixed-refrigerant receiving region 330 may extend between a first mixed refrigerant inlet 336, which may be configured to receive compressed refrigerant stream 206, and a first mixed refrigerant outlet 342, which may be configured to discharge cooled and compressed refrigerant stream 352. In addition, second mixed-refrigerant-receiving region 360 may extend between a second mixed refrigerant inlet 366, which may be configured to receive expanded refrigerant stream 374, and a second mixed refrigerant outlet 376, which may be configured to discharge warmed and expanded refrigerant stream 202.

[0065] In such a configuration, system 10 may be configured to provide both liquid compressed refrigerant stream 316 of Fig. 1 and vapor compressed refrigerant stream 318 of Fig. 1, when generated, to first mixed refrigerant inlet 336 as compressed refrigerant stream 206. Additionally or alternatively, compressed refrigerant stream 206 may be provided to first mixed refrigerant inlet 336 without first being separated within compressed refrigerant liquid- vapor separator 314 of Fig. 1.

[0066] Turning to Figs. 5-6, and in some examples, cryogenic heat exchange module 300 may include a fourth fluidic pass 304, which also may be defined by first mixed-refrigerant- receiving region 330. In such a configuration, first mixed-refrigerant-receiving region 330 may include a first liquid-mixed-refrigerant-receiving region 332 and a first vapor-mixed- refrigerant-receiving region 334. Also in such a configuration, first mixed refrigerant inlet 336 may include a first liquid mixed refrigerant inlet 338, which may be configured to receive liquid compressed refrigerant stream 316, and a first vapor mixed refrigerant inlet 340, which may be configured to receive vapor compressed refrigerant stream 318. Similarly, first mixed refrigerant outlet 342 may include a first liquid mixed refrigerant outlet 344, which may be configured to discharge a cooled liquid compressed refrigerant stream 346, and a first vapor mixed refrigerant outlet 348, which may be configured to discharge a cooled vapor compressed refrigerant stream 350. First liquid-mixed-refrigerant-receiving region 332 may extend between first liquid mixed refrigerant inlet 338 and first liquid mixed refrigerant outlet 344. Similarly, first vapor mixed-refrigerant-receiving region 334 may extend between first vapor mixed refrigerant inlet 340 and first vapor mixed refrigerant outlet 348. [0067] In the above-described example, cryogenic heat exchange module 300 may be configured to provide cooled vapor compressed refrigerant stream 350 to mixed refrigerant expansion module 400 as cooled and compressed refrigerant stream 352. Also in the above- described example, cryogenic heat exchange module 300 may include a liquid refrigerant expansion structure 382, examples of which include a Joule-Thomson valve, a work-producing turboexpander, and/or a work-producing hydraulic turbine. Liquid refrigerant expansion structure 382 may be configured to receive and expand cooled liquid compressed refrigerant stream 346 to generate an expanded and cooled at least partially liquid refrigerant stream 384. [0068] In the four fluidic pass 304 cryogenic heat exchange module 300 that is illustrated in Fig. 5, second mixed-refrigerant-receiving region 360 may include a mixing structure 385, which may be configured to combine expanded and cooled at least partially liquid refrigerant stream with expanded refrigerant stream 374. In some such examples, mixing structure 385 may be configured to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream internal to the cryogenic heat exchange module. In some examples, mixing structure 385 may be configured to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream external to the cryogenic heat exchange module. In some examples, mixing structure 385 may include and/or be a central inlet 386 configured to receive the expanded and cooled liquid compressed refrigerant stream and to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream.

[0069] In the five fluid pass 304 cryogenic heat exchange module 300 that is illustrated in Fig. 6, second mixed-refrigerant-receiving region 360 may include a second liquid-mixed- refrigerant-receiving region 362 and a second vapor-mixed-refrigerant-receiving region 364.

Similarly, second mixed refrigerant inlet 366 may include a second at least partially liquid mixed refrigerant inlet 368, which is configured to receive expanded and cooled at least partially liquid refrigerant stream 384, and a second at least partially vapor mixed refrigerant inlet 370, which is configured to receive the expanded refrigerant stream 374. In addition, second mixed refrigerant outlet 376 may include a second at least partially liquid mixed refrigerant outlet 378, which is configured to discharge expanded and cooled at least partially liquid refrigerant stream 384, and a second vapor mixed refrigerant outlet 380, which is configured to discharge expanded refrigerant stream 374. In such a configuration, and subsequent to discharge from cryogenic heat exchange module 300, system 10 may be configured to discharge expanded and cooled at least partially liquid refrigerant stream 384 and expanded refrigerant stream 374 to mixed refrigerant compression module 200 as warmed and expanded refrigerant stream 202.

[0070] Fig. 7 is a schematic illustration of examples of mixed refrigerant expansion modules 400 that may be utilized with systems 10 configured to liquefy natural gas 110, according to the present disclosure. Fig. 7 may include and/or be a more detailed illustration of examples of mixed refrigerant expansion module 400 that is illustrated in Fig. 1, and any of the structures, functions, and/or features of mixed refrigerant expansion modules 400 that are discussed herein with reference to Fig. 7 may be included in and/or utilized with systems 10 and/or mixed refrigerant expansion module 400 of Fig. 1 without departing from the scope of the present disclosure. Similarly, any of the structures, functions, and/or features of systems 10 and/or of mixed refrigerant expansion module 400 that are discussed herein with reference to Fig. 1 may be included in and/or utilized with mixed refrigerant expansion modules 400 of Fig. 7 without departing from the scope of the present disclosure.

[0071] Mixed refrigerant expansion modules 400 may be configured to receive cooled and compressed refrigerant stream 352 and to expand the cooled and compressed refrigerant stream, utilizing work-producing mixed-refrigerant hydraulic turbine 405, to produce and/or generate expanded refrigerant stream 374. In some examples, work-producing mixed- refrigerant hydraulic turbine 405 may be configured to expand both liquid and gaseous mixed refrigerant within cooled and compressed refrigerant stream 352 to generate expanded refrigerant stream 374. In some such examples, work-producing mixed-refrigerant hydraulic turbine 405 also may be referred to herein as, and/or may be, a dual-phase work-producing mixed-refrigerant hydraulic turbine 405. [0072] In some examples, work-producing mixed-refrigerant hydraulic turbine 405 may be configured to receive and expand cooled and compressed refrigerant stream 352 to generate an at least partially expanded refrigerant stream 415. In some such examples, work-producing mixed-refrigerant hydraulic turbine 405 may be referred to herein as, and/or may be, a single phase work-producing mixed-refrigerant hydraulic turbine 405. Also in some such examples, mixed refrigerant expansion module 400 further may include an expansion valve 420.

Expansion valve 420, when present, may be configured to receive and expand at least partially expanded refrigerant stream 415 to produce and/or generate expanded refrigerant stream 374. An example of expansion valve 420 includes a Joule-Thomson valve. [0073] As illustrated in dashed lines in Fig. 7, mixed refrigerant expansion module 400 may include a bypass valve 425. Bypass valve 425, when present, may be configured to selectively bypass work-producing mixed-refrigerant hydraulic turbine 405, such as responsive to failure of the work-producing mixed refrigerant hydraulic turbine. [0074] As also illustrated in dashed lines in Fig. 7, mixed refrigerant expansion module

400 may include an expansion module generator 440. Expansion module generator 440, when present, may be configured to be powered by work-producing mixed-refrigerant hydraulic turbine 405 and/or to generate an expansion module electric current.

[0075] Fig. 8 is a schematic illustration of examples of heavy hydrocarbon recovery modules 500 that may be utilized with systems 10 configured to liquefy natural gas 110, according to the present disclosure. Fig. 8 may include and/or be a more detailed illustration of examples heavy hydrocarbon expansion module 500 that is illustrated in Fig. 1, and any of the structures, functions, and/or features of heavy hydrocarbon expansion modules 500 that are discussed herein with reference to Fig. 8 may be included in and/or utilized with systems 10 and/or heavy hydrocarbon expansion module 500 of Fig. 1 without departing from the scope of the present disclosure. Similarly, any of the structures, functions, and/or features of systems 10 and/or of heavy hydrocarbon expansion module 500 that are discussed herein with reference to Fig. 1 may be included in and/or utilized with heavy hydrocarbon expansion modules 500 of Fig. 8 without departing from the scope of the present disclosure. [0076] As discussed, heavy hydrocarbon recovery module 500, when utilized, may be configured to receive and separate raw feed stream 505 into heavy hydrocarbon stream 510 and feed stream 105. As also discussed, system 10 may provide heavy hydrocarbon stream 510 to mixed refrigerant compression module 200 as mixed refrigerant make-up stream 252. [0077] This separation of raw feed stream 505 may be accomplished in any suitable manner. As an example, heavy hydrocarbon recovery module 500 may include a separation column 515, which may be configured to separate the raw feed stream into the heavy hydrocarbon stream and the feed stream. As another example, and as discussed, heavy hydrocarbon recovery module 500 may be configured to receive a slip stream 525 from cooled and compressed feed stream 115, which may be provided to separation column 515, such as to generate reflux within the separation column. In some such examples, heavy hydrocarbon recovery module 500 may include a liquid-vapor separator 530, which may be configured to separate liquid and gaseous components of slip stream 525 prior to supply of the slip stream to the separation column. As another example, heavy hydrocarbon recovery module 500 may include a heat exchanger 520, which may be configured to exchange thermal energy among raw feed stream 505, slip stream 525, and/or feed stream 105.

[0078] Components of system 10, including feed gas compression and expansion module 100, natural gas liquefaction module 190, mixed refrigerant compression module 200, cryogenic heat exchange module 300, mixed refrigerant expansion module 400, heavy hydrocarbon recovery module 500, refrigeration module 600, and/or outlet stream expansion module 700, may have a modular construction. This modular construction may permit and/or facilitate assembly of various combinations of these modules in order to scale for different flow rates of feed stream 105 and/or other site-specific conditions. [0079] It is within the scope of the present disclosure that any of feed gas compression and expansion module 100, natural gas liquefaction module 190, mixed refrigerant compression module 200, cryogenic heat exchange module 300, mixed refrigerant expansion module 400, heavy hydrocarbon recovery module 500, refrigeration module 600, and/or outlet stream expansion module 700 may be manufactured on-site and/or may be prefabricated modules that may be shipped to a location for systems 10. Additionally or alternatively, it is also within the scope of the present disclosure that any of feed gas compression and expansion module 100, natural gas liquefaction module 190, mixed refrigerant compression module 200, cryogenic heat exchange module 300, mixed refrigerant expansion module 400, heavy hydrocarbon recovery module 500, refrigeration module 600, and/or outlet stream expansion module 700 may be utilized to retrofit conventional single mixed refrigerant systems, such as to convert the conventional single mixed refrigerant systems to systems 10, which are disclosed herein. [0080] Fig. 9 is a flowchart depicting examples of methods 800 of liquefying natural gas, according to the present disclosure. Methods 800 may include separating a raw feed stream at 805 and include cooling and compressing a feed stream at 810. Methods 800 also may include cooling a cooled and compressed feed stream at 815, and methods 800 include cooling and compressing a warmed and expanded refrigerant stream at 820. Methods 800 further may include providing a heavy hydrocarbon stream at 825, and methods 800 include flowing the cooled and compressed feed stream at 830, flowing a compressed refrigerant stream at 835, expanding the cooled and compressed refrigerant stream at 840, and flowing an expanded refrigerant stream at 845. Methods 800 also may include expanding an at least partially liquefied outlet stream at 850.

[0081] Separating the raw feed stream at 805 may include separating the raw feed stream into a heavy hydrocarbon stream and the feed stream. Additionally or alternatively, the separating at 805 may include separating with, via, and/or utilizing a heavy hydrocarbon recovery module. Examples of the raw feed stream are disclosed herein with reference to raw feed stream 505. Examples of the heavy hydrocarbon stream are disclosed herein with reference to heavy hydrocarbon stream 510. Example of the heavy hydrocarbon recovery module are disclosed herein with reference to heavy hydrocarbon recovery module 500. [0082] The separating at 805 may be performed with any suitable timing and/or sequence during methods 800. As examples, the separating at 805 may be performed prior to and/or at least partially concurrently with the cooling and compressing at 810, the cooling at 815, the cooling and compressing at 820, the providing at 825, the flowing at 830, the flowing at 835, the expanding at 840, the flowing at 845, and/or the expanding at 850.

[0083] Cooling and compressing the feed stream at 810 may include cooling and compressing any suitable feed stream, which includes natural gas, to generate the cooled and compressed feed stream. This may include cooling and compressing the feed stream at least partially by utilizing a work-producing feed expander of a feed gas compression and expansion module. Examples of the feed stream are disclosed herein with reference to feed stream 105. Examples of the work-producing feed expander are disclosed herein with reference to work- producing feed expander 120. Examples of the feed gas compression and expansion module are disclosed herein with reference to feed gas compression and expansion module 100.

[0084] Cooling the cooled and compressed feed stream at 815 may include cooling the cooled and compressed feed stream utilizing a refrigeration module. Examples of the refrigeration module are disclosed herein with reference to refrigeration module 600. The cooling at 815 may be performed with any suitable timing and/or sequence during methods 800. As examples, the cooling at 815 may be performed prior to and/or at least partially concurrently with the cooling and compressing at 820, the providing at 825, the flowing at 830, the flowing at 835, the expanding at 840, the flowing at 845, and/or the expanding at 850. [0085] Cooling and compressing the warmed and expanded refrigerant stream at 820 may include cooling and compressing any suitable warmed and expanded refrigerant stream, which includes a mixed refrigerant, to produce and/or generate the compressed refrigerant stream. This may include cooling and compressing with, via, and/or utilizing a mixed refrigerant compression module, examples of which are disclosed herein with reference to mixed refrigerant compression module 200.

[0086] Providing the heavy hydrocarbon stream at 825 may include providing the heavy hydrocarbon stream, which is produced during the separating at 805, to the mixed refrigerant compression module. This may include providing the heavy hydrocarbon stream to the mixed refrigerant compression module as a mixed refrigerant make-up stream for the mixed refrigerant compression module.

[0087] Flowing the cooled and compressed feed stream at 830 may include flowing the cooled and compressed feed stream through a natural-gas-receiving region of a cryogenic heat exchange module. This may include flowing the cooled and compressed feed stream to produce and/or generate an at least partially liquefied outlet stream. Examples of the natural- gas-receiving region are disclosed herein with reference to natural-gas-receiving region 306. Examples of the cryogenic heat exchange module are disclosed herein with reference to cryogenic heat exchange module 300. Examples of the at least partially liquefied outlet stream are disclosed herein with reference to at least partially liquefied outlet stream 312. [0088] Flowing the compressed refrigerant stream at 835 may include flowing the compressed refrigerant stream through a first mixed-refrigerant-receiving region of the cryogenic heat exchange module. This may include flowing to produce and/or generate a cooled and compressed refrigerant stream. Examples of the first mixed-refrigerant-receiving region are disclosed herein with reference to first mixed-refrigerant-receiving region 330. Examples of the cooled and compressed refrigerant stream are disclosed herein with reference to cooled and compressed refrigerant stream 352.

[0089] Expanding the cooled and compressed refrigerant stream at 840 may include expanding the cooled and compressed refrigerant stream to produce and/or generate an expanded refrigerant stream. This may include expanding with, via, and/or utilizing a work- producing mixed-refrigerant hydraulic turbine of a mixed refrigerant expansion module. Examples of the expanded refrigerant stream are disclosed herein with reference to expanded refrigerant stream 374. Examples of the work-producing mixed-refrigerant hydraulic turbine are disclosed herein with reference to work-producing mixed-refrigerant hydraulic turbine 405.

Examples of the mixed refrigerant expansion module are disclosed herein with reference to mixed refrigerant expansion module 400.

[0090] Flowing the expanded refrigerant stream at 845 may include flowing the expanded refrigerant stream through a second mixed-refrigerant-receiving region of the cryogenic heat exchange module. This may include flowing to produce and/or generate the warmed and expanded refrigerant stream, such as via transfer of thermal energy from the natural-gas- receiving region and from the first mixed-refrigerant-receiving region to the second mixed- refrigerant-receiving region. Examples of the second mixed-refrigerant-receiving region are disclosed herein with reference to second mixed-refrigerant-receiving region 360. [0091] Expanding the at least partially liquefied outlet stream at 850 may include expanding the at least partially liquefied outlet stream to produce and/or generate an expanded outlet stream. This may include expanding with, via, and/or utilizing an outlet stream expansion module, examples of which are disclosed herein with reference to outlet stream expansion module 700.

[0092] As discussed herein with reference to Fig. 1, a single feed gas compression and expansion module may be utilized to provide the feed stream to a plurality of natural gas liquefaction modules. With this in mind, methods 800 may include performing the cooling and compressing at 810 utilizing a single feed gas compression module and simultaneously performing the cooling and compressing at 820, the flowing at 830, the flowing at 835, the expanding at 840, and the flowing at 845 utilizing a plurality of distinct and/or spaced-apart natural gas liquefaction modules. [0093] In the present disclosure, several of the illustrative, non-exclusive examples have been discussed and/or presented in the context of flow diagrams, or flow charts, in which the methods are shown and described as a series of blocks, or steps. Unless specifically set forth in the accompanying description, it is within the scope of the present disclosure that the order of the blocks may vary from the illustrated order in the flow diagram, including with two or more of the blocks (or steps) occurring in a different order and/or concurrently.

[0094] As used herein, the term “and/or” placed between a first entity and a second entity means one of (1) the first entity, (2) the second entity, and (3) the first entity and the second entity. Multiple entities listed with “and/or” should be construed in the same manner, i.e., “one or more” of the entities so conjoined. Other entities may optionally be present other than the entities specifically identified by the “and/or” clause, whether related or unrelated to those entities specifically identified. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” may refer, in one embodiment, to A only (optionally including entities other than B); in another embodiment, to B only (optionally including entities other than A); in yet another embodiment, to both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, and the like.

[0095] As used herein, the phrase “at least one,” in reference to a list of one or more entities should be understood to mean at least one entity selected from any one or more of the entities in the list of entities, but not necessarily including at least one of each and every entity specifically listed within the list of entities and not excluding any combinations of entities in the list of entities. This definition also allows that entities may optionally be present other than the entities specifically identified within the list of entities to which the phrase “at least one” refers, whether related or unrelated to those entities specifically identified. Thus, as a non limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) may refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including entities other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including entities other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other entities). In other words, the phrases “at least one,” “one or more,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B, and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C,” and “A, B, and/or C” may mean A alone, B alone, C alone, A and B together, A and C together, B and C together, A, B, and C together, and optionally any of the above in combination with at least one other entity. [0096] In the event that any patents, patent applications, or other references are incorporated by reference herein and (1) define a term in a manner that is inconsistent with and/or (2) are otherwise inconsistent with, either the non-incorporated portion of the present disclosure or any of the other incorporated references, the non-incorporated portion of the present disclosure shall control, and the term or incorporated disclosure therein shall only control with respect to the reference in which the term is defined and/or the incorporated disclosure was present originally.

[0097] As used herein the terms “adapted” and “configured” mean that the element, component, or other subject matter is designed and/or intended to perform a given function. Thus, the use of the terms “adapted” and “configured” should not be construed to mean that a given element, component, or other subject matter is simply “capable of’ performing a given function but that the element, component, and/or other subject matter is specifically selected, created, implemented, utilized, programmed, and/or designed for the purpose of performing the function. It is also within the scope of the present disclosure that elements, components, and/or other recited subject matter that is recited as being adapted to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa.

[0098] As used herein, the phrase, “for example,” the phrase, “as an example,” and/or simply the term “example,” when used with reference to one or more components, features, details, structures, embodiments, and/or methods according to the present disclosure, are intended to convey that the described component, feature, detail, structure, embodiment, and/or method is an illustrative, non-exclusive example of components, features, details, structures, embodiments, and/or methods according to the present disclosure. Thus, the described component, feature, detail, structure, embodiment, and/or method is not intended to be limiting, required, or exclusive/exhaustive; and other components, features, details, structures, embodiments, and/or methods, including structurally and/or functionally similar and/or equivalent components, features, details, structures, embodiments, and/or methods, are also within the scope of the present disclosure.

[0099] As used herein, “at least substantially,” when modifying a degree or relationship, may include not only the recited “substantial” degree or relationship, but also the full extent of the recited degree or relationship. A substantial amount of a recited degree or relationship may include at least 75% of the recited degree or relationship. For example, an object that is at least substantially formed from a material includes objects for which at least 75% of the objects are formed from the material and also includes objects that are completely formed from the material. As another example, a first length that is at least substantially as long as a second length includes first lengths that are within 75% of the second length and also includes first lengths that are as long as the second length. Industrial Applicability

[0100] The systems and methods disclosed herein are applicable to the natural gas production, liquefaction, transport, and storage industries.

[0101] It is believed that the disclosure set forth above encompasses multiple distinct inventions with independent utility. While each of these inventions has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. The subject matter of the inventions includes all novel and non-obvious combinations and subcombinations of the various elements, features, functions, and/or properties disclosed herein. Similarly, where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.

[0102] It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed inventions and are novel and non-obvious. Inventions embodied in other combinations and subcombinations of features, functions, elements, and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different invention or directed to the same invention, whether different, broader, narrower, or equal in scope to the original claims, are also regarded as included within the subject matter of the inventions of the present disclosure.

Claims

1. A system configured to liquefy natural gas, the system comprising: a feed gas compression and expansion module configured to receive a feed stream, which includes natural gas, and to compress and cool the feed stream to generate a cooled and compressed feed stream, wherein the feed gas compression and expansion module includes a work-producing feed expander; a mixed refrigerant compression module configured to receive a warmed and expanded refrigerant stream, which includes a mixed refrigerant, and to compress and cool the warmed and expanded refrigerant stream to generate a compressed refrigerant stream; a cryogenic heat exchange module configured to facilitate thermal energy transfer from the natural gas to the mixed refrigerant, the cryogenic heat exchange module including a natural-gas- receiving region, which is configured to receive the cooled and compressed feed stream and to discharge an at least partially liquefied outlet stream that includes liquefied natural gas, a first mixed-refrigerant-receiving region configured to receive the compressed refrigerant stream and to discharge a cooled and compressed refrigerant stream, and a second mixed-refrigerant-receiving region configured to receive an expanded refrigerant stream and to discharge the warmed and expanded refrigerant stream, wherein the second mixed-refrigerant-receiving region is in thermal communication with both the natural-gas-receiving region and the first mixed-refrigerant receiving region; and a mixed refrigerant expansion module configured to receive the cooled and compressed refrigerant stream from the cryogenic heat exchange module and to expand the cooled and compressed refrigerant stream to generate the expanded refrigerant stream, wherein the mixed refrigerant expansion module includes a work-producing mixed refrigerant hydraulic turbine.

2. The system of claim 1, wherein the feed gas compression and expansion module includes:

(i) a first feed compressor, which is configured to receive the feed stream and to compress the feed stream to generate a partially compressed feed stream; (ii) a second feed compressor, which is configured to receive the partially compressed feed stream and to compress the partially compressed feed stream to generate a compressed feed stream; and

(iii) the work-producing feed expander, which is configured to receive the compressed feed stream and to expand and cool the compressed feed stream to generate the cooled and compressed feed stream and feed expansion work.

3. The system of claim 2, wherein the feed gas compression and expansion module further includes a first feed cooler, which is configured to cool the partially compressed feed stream prior to supply of the partially compressed feed stream to the second feed compressor.

4. The system of any of claims 2-3, wherein the feed gas compression and expansion module further includes a second feed cooler, which is configured to cool the compressed feed stream prior to supply of the compressed feed stream to the work-producing feed expander.

5. The system of any of claims 2-4, wherein the feed gas compression and expansion module further includes at least one of: (i) a first linkage that conveys at least a first fraction of feed expansion work from the work-producing feed expander to the first feed compressor to at least partially power the first feed compressor with the feed expansion work; and

(ii) a second linkage that conveys at least a second fraction of the feed expansion work from the work-producing feed expander to the second feed compressor to at least partially power the second feed compressor with the feed expansion work

6. The system of any of claims 2-5, wherein the feed gas compression and expansion module further includes at least one of: (i) a feed compressor motor configured to at least partially power at least one of the first feed compressor and the second feed compressor;

(ii) a feed compressor gas turbine configured to at least partially power at least one of the first feed compressor and the second feed compressor; and

(iii) a feed compressor stream turbine configured to at least partially power at least one of the first feed compressor and the second feed compressor.

7. The system of any of claims 2-6, wherein the feed gas compression and expansion module further includes a feed gas bypass configured to selectively bypass at least one of the first feed compressor, the second feed compressor, and the work-producing feed expander, optionally responsive to failure of at least one of the first feed compressor, the second feed compressor, and the work-producing feed expander.

8. The system of any of claims 2-7, wherein the work-producing feed expander includes a feed turboexpander.

9. The system of any of claims 1-8, wherein the mixed refrigerant compression module includes only a single compression stage.

10. The system of any of claims 1-9, wherein the mixed refrigerant compression module includes:

(i) a mixed refrigerant liquid-vapor separator configured to receive the warmed and expanded refrigerant stream and to separate the warmed and expanded refrigerant stream into a warmed and expanded liquid refrigerant stream and a warmed and expanded vapor refrigerant stream;

(ii) a mixed refrigerant liquid pump configured to receive and compress the warmed and expanded liquid refrigerant stream to generate a compressed liquid refrigerant stream; and

(iii) a mixed refrigerant vapor compressor configured to receive and compress the warmed and expanded vapor refrigerant stream to generate a compressed vapor refrigerant stream; and wherein the mixed refrigerant compression module is configured to discharge a combination of the compressed liquid refrigerant stream and the compressed vapor refrigerant stream as the compressed refrigerant stream.

11. The system of any of claims 1-8, wherein the mixed refrigerant compression module includes a plurality of compression stages.

12. The system of any of claims 1-8 or 11, wherein the mixed refrigerant compression module includes at least: (i) a first mixed refrigerant liquid-vapor separator configured to receive and separate the warmed and expanded refrigerant stream to generate a warmed and expanded liquid refrigerant stream and a warmed and expanded vapor refrigerant stream;

(ii) a first mixed refrigerant liquid pump configured to receive and compress the warmed and expanded liquid refrigerant stream to generate a first partially compressed liquid refrigerant stream;

(iii) a first mixed refrigerant vapor compressor configured to receive and compress the warmed and expanded vapor refrigerant stream to generate a first partially compressed vapor refrigerant stream; (iv) a second mixed refrigerant liquid-vapor separator configured to receive and separate the first partially compressed liquid refrigerant stream and the first partially compressed vapor refrigerant stream and to generate a second partially compressed liquid refrigerant stream and a second partially compressed vapor refrigerant stream;

(v) a second mixed refrigerant liquid pump configured to receive and compress the second partially compressed liquid refrigerant stream to generate a compressed liquid refrigerant stream; and

(vi) a second mixed refrigerant vapor compressor configured to receive and compress the second partially compressed vapor refrigerant stream to generate a compressed vapor refrigerant stream; and wherein the mixed refrigerant compression module is configured to discharge a combination of the compressed liquid refrigerant stream and the compressed vapor refrigerant stream as the compressed refrigerant stream.

13. The system of claim 12, wherein the mixed refrigerant compression module further includes a partially compressed vapor cooler configured to cool the first partially compressed vapor refrigerant stream.

14. The system of any of claims 8-13, wherein the mixed refrigerant compression module includes at least one of:

(i) a compressed liquid refrigerant cooler configured to cool the compressed liquid refrigerant stream;

(ii) a compressed vapor refrigerant cooler configured to cool the compressed vapor refrigerant stream; and

(iii) a compressed refrigerant stream cooler configured to cool the compressed refrigerant stream.

15. The system of any of claims 1-14, wherein the mixed refrigerant compression module further includes a mixed refrigerant make-up inlet configured to receive a mixed refrigerant make-up stream and to combine the mixed refrigerant make-up stream with the mixed refrigerant.

16. The system of any of claims 1-15, wherein the cryogenic heat exchange module includes a brazed aluminum heat exchanger.

17. The system of any of claims 1-16, wherein the cryogenic heat exchange module includes a wound coil heat exchanger.

18. The system of any of claims 1-17, wherein the compressed refrigerant stream is heated, within the first mixed-refrigerant-receiving region and via thermal exchange with the natural-gas-receiving region, and also cooled, within the first mixed-refrigerant-receiving region and via thermal exchange with the second mixed-refrigerant-receiving region, to generate the cooled and compressed refrigerant stream.

19. The system of any of claims 1-18, wherein the expanded refrigerant stream is heated, within the second mixed-refrigerant-receiving region and via thermal exchange with both the natural gas-receiving region and the first mixed-refrigerant-receiving region, to generate the warmed and expanded refrigerant stream.

20. The system of any of claims 1-19, wherein the cooled and compressed feed stream is cooled, within the natural-gas-receiving region and via thermal exchange with the first mixed- refrigerant-receiving region, to produce the at least partially liquefied outlet stream.

21. The system of any of claims 1-20, wherein the natural-gas-receiving region extends between a natural gas inlet, which is configured to receive the cooled and compressed feed stream, and a natural gas outlet, which is configured to discharge the at least partially liquefied outlet stream.

22. The system of any of claims 1-21, wherein the natural-gas-receiving region of the cryogenic heat exchange module is free of a heavy hydrocarbon recovery region.

23. The system of any of claims 1-22, wherein the cryogenic heat exchange module includes a buffer region within which the natural-gas-receiving region is thermally isolated from the first mixed-refrigerant-receiving region and within which the first mixed-refrigerant-receiving region is in thermal communication with the second mixed-refrigerant-receiving region.

24. The system of claim 23, wherein the buffer region extends along at least one of:

(i) at least 3% of a length of the cryogenic heat exchange module; and

(ii) at most 15% of the length of the cryogenic heat exchange module.

25. The system of any of claims 1-24, wherein the system further includes a compressed refrigerant liquid-vapor separator configured to receive and separate the compressed refrigerant stream into a liquid compressed refrigerant stream and a vapor compressed refrigerant stream.

26. The system of claim 25, wherein the cryogenic heat exchange module is a three fluidic pass cryogenic heat exchanger.

27. The system of any of claims 25-26, wherein the first mixed-refrigerant-receiving region extends between a first mixed refrigerant inlet, which is configured to receive the compressed refrigerant stream, and a first mixed refrigerant outlet, which is configured to discharge the cooled and compressed refrigerant stream.

28. The system of claim 27, wherein the system is configured to provide both the liquid compressed refrigerant stream and the vapor compressed refrigerant stream to the first mixed refrigerant inlet of the cryogenic heat exchange module as the compressed refrigerant stream.

29. The system of any of claims 26-28, wherein the cryogenic heat exchange module is a four fluidic pass cryogenic heat exchanger.

30. The system of any of claims 26-29, wherein:

(i) the first mixed-refrigerant-receiving region includes a first liquid-mixed- refrigerant-receiving region and a first vapor-mixed-refrigerant-receiving region;

(ii) the first mixed refrigerant inlet includes a first liquid mixed refrigerant inlet, which is configured to receive the liquid compressed refrigerant stream, and a first vapor mixed refrigerant inlet, which is configured to receive the vapor compressed refrigerant stream;

(iii) the first mixed refrigerant outlet includes a first liquid mixed refrigerant outlet, which is configured to discharge a cooled liquid compressed refrigerant stream, and a first vapor mixed refrigerant outlet, which is configured to discharge a cooled vapor compressed refrigerant stream;

(iv) the first liquid-mixed-refrigerant-receiving region extends between the first liquid mixed refrigerant inlet and the first liquid mixed refrigerant outlet; (v) the first vapor-mixed-refrigerant-receiving region extends between the first vapor mixed refrigerant inlet and the first vapor mixed refrigerant outlet;

(vi) the cryogenic heat exchange module is configured to provide the cooled vapor compressed refrigerant stream to the mixed refrigerant expansion module as the cooled and compressed refrigerant stream; and (vii) the cryogenic heat exchange module further includes a liquid refrigerant expansion structure configured to receive and expand the cooled liquid compressed refrigerant stream to generate an expanded and cooled at least partially liquid refrigerant stream.

31. The system of claim 30, wherein the second mixed-refrigerant-receiving region further includes a mixing structure configured to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream, optionally wherein the mixing structure at least one of:

(i) is configured to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream internal to the cryogenic heat exchange module,

(ii) is configured to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream external to the cryogenic heat exchange module, and (iii) includes a central inlet configured to receive the expanded and cooled at least partially liquid refrigerant stream and to combine the expanded and cooled at least partially liquid refrigerant stream with the expanded refrigerant stream.

32. The system of any of claims 30-31, wherein the second mixed-refrigerant-receiving region extends between a second mixed refrigerant inlet, which is configured to receive the expanded refrigerant stream, and a second mixed refrigerant outlet, which is configured to discharge the warmed and expanded refrigerant stream.

33. The system of claim 32, wherein:

(i) the second mixed-refrigerant-receiving region includes a second liquid-mixed- refrigerant-receiving region and a second vapor-mixed-refrigerant-receiving region;

(ii) the second mixed refrigerant inlet includes a second at least partially liquid mixed refrigerant inlet, which is configured to receive the expanded and cooled at least partially liquid refrigerant stream, and a second at least partially vapor mixed refrigerant inlet, which is configured to receive the expanded refrigerant stream;

(iii) the second mixed refrigerant outlet includes a second at least partially liquid mixed refrigerant outlet, which is configured to discharge the expanded and cooled at least partially liquid refrigerant stream, and a second vapor mixed refrigerant outlet, which is configured to discharge the expanded refrigerant stream;

34. The system of any of claims 32-33, wherein the system is configured to provide the expanded and cooled at least partially liquid refrigerant stream and the expanded refrigerant stream to the mixed refrigerant compression module as the warmed and expanded refrigerant stream.

35. The system of any of claims 26-34, wherein the cryogenic heat exchange module is a five fluidic pass cryogenic heat exchanger.

36. The system of any of claims 1-35, wherein the work-producing mixed refrigerant hydraulic turbine is configured to receive and expand the cooled and compressed refrigerant stream to generate the expanded refrigerant stream.

37. The system of any of claims 1-36, wherein the work-producing mixed refrigerant hydraulic turbine is configured to receive and expand the cooled and compressed refrigerant stream to generate an at least partially expanded refrigerant stream.

38. The system of claim 37, wherein the mixed refrigerant expansion module further includes an expansion valve configured to receive and expand the at least partially expanded refrigerant stream to generate the expanded refrigerant stream.

39. The system of any of claims 1-38, wherein the mixed refrigerant expansion module includes a bypass valve configured to selectively bypass the work-producing mixed refrigerant hydraulic turbine responsive to failure of the work-producing mixed refrigerant hydraulic turbine.

40. The system of any of claims 1-39, wherein the mixed refrigerant expansion module further includes an expansion module generator.

41. The system of claim 40, wherein the expansion module generator is configured to be powered by the work-producing mixed refrigerant hydraulic turbine to generate an expansion module electric current.

42. The system of any of claims 1-41, wherein the system further includes a heavy hydrocarbon recovery module configured to receive and separate a raw feed stream into a heavy hydrocarbon stream and the feed stream.

43. The system of claim 42, wherein the system is configured to provide the heavy hydrocarbon stream to the feed gas compression and expansion module as the mixed refrigerant make-up stream for the mixed refrigerant compression module.

44. The system of any of claims 42-43, wherein the heavy hydrocarbon recovery module includes a separation column configured to separate the raw feed stream into the heavy hydrocarbon stream and the feed stream.

45. The system of claim 44, wherein the system is configured to provide a slip stream from the cooled and compressed feed stream to the separation column to generate reflux within the separation column.

46. The system of any of claims 1-45, wherein the system further includes a refrigeration module configured to further cool the cooled and compressed feed stream prior to supply of the cooled and compressed feed stream to the cryogenic heat exchange module.

47. The system of claim 46, wherein the refrigeration module includes a direct expansion refrigeration module.

48. The system of any of claims 1-47, wherein the system further includes an outlet stream expansion module configured to receive and expand the at least partially liquefied outlet stream to generate an expanded outlet stream.

49. The system of claim 48, wherein the outlet stream expansion module includes a work-producing outlet stream expander.

50. The system of claim 49, wherein the system further includes an outlet stream module generator configured to be powered by the work-producing outlet stream expander to generate an outlet stream electric current.

51. The system of any of claims 48-50, wherein the outlet stream expansion module includes an outlet stream expansion valve.

52. The system of any of claims 1-51, wherein the mixed refrigerant includes at least 6 mole percent and at most 14 mole percent nitrogen gas.

53. The system of any of claims 1-52, wherein the mixed refrigerant includes at least 25 mole percent and at most 35 mole percent methane.

54. The system of any of claims 1-53, wherein the mixed refrigerant includes at least 25 mole percent and at most 35 mole percent ethane.

55. The system of any of claims 1-54, wherein the mixed refrigerant includes at least 6 mole percent and at most 14 mole percent propane.

56. The system of any of claims 1-55, wherein the mixed refrigerant includes at least 3 mole percent and at most 10 mole percent butane.

57. The system of any of claims 1-56, wherein the mixed refrigerant includes at least 9 mole percent and at most 16 mole percent pentane.

58. The system of any of claims 1-57, wherein the mixed refrigerant compression module, the cryogenic heat exchange module, and the mixed refrigerant expansion module together define a natural gas liquefaction module, wherein the system includes a plurality of natural gas liquefaction modules, and further wherein the feed gas compression and expansion module is configured to provide the cooled and compressed feed stream to the plurality of natural gas liquefaction modules.

59. The system of claim 58, wherein the plurality of natural gas liquefaction modules includes at least 6 natural gas liquefaction modules.

60. A method of liquefying natural gas, the method comprising: cooling and compressing a feed stream, which includes natural gas, utilizing a work- producing feed expander of a feed gas compression and expansion module to generate a cooled and compressed feed stream; cooling and compressing a warmed and expanded refrigerant stream, which includes a mixed refrigerant, utilizing a mixed refrigerant compression module to generate a compressed refrigerant stream; flowing the cooled and compressed feed stream through a natural-gas-receiving region of a cryogenic heat exchange module to produce an at least partially liquefied outlet stream; flowing the compressed refrigerant stream through a first mixed-refrigerant-receiving region of the cryogenic heat exchange module to produce a cooled and compressed refrigerant stream; expanding the cooled and compressed refrigerant stream utilizing a work-producing mixed refrigerant hydraulic turbine of a mixed refrigerant expansion module to generate an expanded refrigerant stream; and flowing the expanded refrigerant stream through a second mixed-refrigerant-receiving region of the cryogenic heat exchange module to generate the warmed and expanded refrigerant stream; wherein the second mixed-refrigerant-receiving region is in thermal communication with both the natural-gas-receiving region and the first mixed-refrigerant-receiving region.

61. The method of claim 60, wherein the method further includes separating a raw feed stream into a heavy hydrocarbon stream and the feed stream utilizing a heavy hydrocarbon recovery module.

62. The method of claim 61, wherein the method further includes providing the heavy hydrocarbon stream to the mixed refrigerant compression module as a mixed refrigerant make-up stream.

63. The method of any of claims 61-62, wherein the separating the raw feed stream includes separating prior to supply of the feed stream to the feed gas compression and expansion module.

64. The method of any of claims 61-63, wherein the heavy hydrocarbon recovery module is spaced-apart from the cryogenic heat exchange module.

65. The method of any of claims 60-64, wherein the method further includes further cooling the cooled and compressed feed stream, utilizing a refrigeration module, prior to the flowing the cooled and compressed feed stream through the natural-gas-receiving region of the cryogenic heat exchange module.

66. The method of any of claims 60-65, wherein the method further includes expanding the at least partially liquefied outlet stream, utilizing an outlet stream expansion module, to generate an expanded outlet stream.

67. The method of any of claims 60-66, wherein the method includes performing the cooling and compressing the feed stream utilizing a single feed gas compression and expansion module and simultaneously performing the cooling and compressing the warmed and expanded refrigerant stream, the flowing the cooled and compressed feed stream, the flowing the compressed refrigerant stream, the expanding the cooled and compressed refrigerant stream, and the flowing the expanded refrigerant stream utilizing a plurality of spaced-apart natural gas liquefaction modules.