RU2700112C2 - Dual system with mixed coolant - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to liquefaction of natural gas. Method of liquefying a gas involves feeding a completely condensed first mixed refrigerant, a compressed second mixed refrigerant and a feed stream into a first cooling system. Further, the first mixed refrigerant is expanded to cool the supplied flow and the compressed second mixed refrigerant in the first cooling system by means of heat exchange with the expanded first mixed refrigerant to form the first cooled flow and the completely condensed second mixed refrigerant. Second mixed refrigerant is expanded. First cooled flow is cooled in the second cooling system by means of heat exchange with the expanded second mixed coolant with formation of the second cooled flow. First or the second cooled flow is expanded in the turbine expander. Expanded flow is separated in separator. Vapour head fraction is compressed in compressor driven by turboexpander. If the first cooled flow is expanded, the compressed vapour fraction is cooled in the first cooling system. If the second cooled flow is expanded, the compressed vapour fraction is cooled in the second cooling system.

EFFECT: technical result is reduction of energy consumption.

19 cl, 7 dwg

Description

State of the art

1. The technical field to which the invention relates.

[0001] The present invention generally relates to methods and systems for recovering liquefied natural gas (“LNG”) from a hydrocarbon-containing gas. More specifically, the present invention generally relates to methods and systems that comprise a dual mixed refrigerant system.

2. Description of the Related Art

[0002] In recent years, the demand for natural gas has been increasing. In many cases, natural gas is located in areas that are located far from natural gas markets. If natural gas is not close enough to the market place, so it is easy to build a pipeline for transporting natural gas, then it needs to be transported using tankers or the like. Transportation of natural gas in the form of vapors requires excessively large volumes of tankers; for this reason, natural gas is usually liquefied for storage and transportation. The use of liquefied natural gas and methods for its storage are well known. Natural gas may also be liquefied at the point of use when it is available in excess, but may be required in large volumes, which may be delivered to the point of use in the future. Such storage can be used, for example, to meet the peak demand for natural gas in the winter, exceeding the capabilities of the existing pipeline system, during periods of winter peak demand. And various other industrial applications require natural gas to be liquefied for storage.

[0003] In the past, substances such as natural gas were liquefied using methods such as described in US Pat. No. 4,033,735, which use a single mixed refrigerant. Such methods have many advantages over other methods, such as cascade systems, in that they require less expensive equipment and are less difficult to control. Unfortunately, single mixed refrigerant processes require slightly more energy than cascade systems.

[0004] Cascading systems, such as the system shown in US Pat. No. 3,855,810, mainly use a plurality of cooling zones in which refrigerants with successively lower boiling points evaporate to provide cooling. However, cascading systems still suffer from inefficiencies.

[0005] Despite the advances made in natural gas liquefaction technologies, improvements in operation efficiency and energy consumption are still needed.

SUMMARY OF THE INVENTION

[0006] One or more embodiments described herein relate to a method for liquefying a hydrocarbon-containing gas. The method includes: (a) introducing a fully condensed first mixed refrigerant, a compressed second mixed refrigerant, and a hydrocarbon-containing gas containing feed stream into the first cooling system; (b) expanding at least a portion of the fully condensed first mixed refrigerant to form an expanded first mixed refrigerant, wherein the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (c) cooling at least a portion of the feed stream and the compressed second mixed refrigerant in the first cooling system by indirect heat exchange with the expanded first mixed refrigerant to form a first cooled feed stream and a fully condensed second mixed refrigerant; (d) expanding at least a portion of the fully condensed second mixed refrigerant to form an expanded second mixed refrigerant, wherein the fully condensed second mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (e) cooling at least a portion of the first chilled feed stream in a second cooling system by indirect heat exchange with the expanded second mixed refrigerant to form a second chilled feed stream; (f) expanding at least a portion of a first cooled feed stream or a second cooled feed stream in a turboexpander to form an expanded feed stream; (g) separating at least a portion of the expanded feed stream in the separator to form a vapor head fraction and a liquid bottom fraction; (h) cooling at least a portion of the vapor head fraction in the first cooling system or second cooling system; and (i) driving the compressor with a turboexpander.

[0007] One or more embodiments described herein relate to a method for liquefying a hydrocarbon-containing gas. The method includes: (a) introducing a fully condensed first mixed refrigerant, a compressed second mixed refrigerant, and a hydrocarbon-containing gas containing feed stream into the first cooling system; (b) expanding at least a portion of the fully condensed first mixed refrigerant to form an expanded first mixed refrigerant; (c) cooling at least a portion of the feed stream and the compressed second mixed refrigerant in the first cooling system by indirect heat exchange with the expanded first mixed refrigerant to form a first cooled feed stream and a fully condensed second mixed refrigerant; (d) expanding at least a portion of the fully condensed second mixed refrigerant to form an expanded second mixed refrigerant; (e) cooling at least a portion of the first chilled feed stream in a second cooling system by indirect heat exchange with the expanded second mixed refrigerant to form a second chilled feed stream; (f) separating at least a portion of the second cooled feed stream in a separator to form a vapor head fraction and a liquid bottom fraction; and (g) cooling at least a portion of the vapor head fraction in the first cooling system or second cooling system.

[0008] One or more of the embodiments described herein relates to a hydrocarbon-containing gas liquefaction system. The system comprises: (a) a first cooling system comprising a first cooling zone located therein, where the first cooling zone is configured to cool a feed stream containing a hydrocarbon-containing gas by indirect heat exchange with a first mixed refrigerant to form a first cooled feed stream; (b) a first closed mixed cooling circuit at least partially located in the first cooling system, where the first closed mixed cooling circuit contains a first mixed refrigerant, wherein the first closed mixed cooling circuit does not contain a phase separator; (c) a second cooling system in fluid communication with the first cooling system, where the second cooling system comprises a second cooling zone located therein, where the second cooling zone is configured to cool the first cooled feed stream by indirect heat exchange with the second mixed refrigerant to form a second chilled feed stream; (d) a second closed mixed cooling circuit at least partially located in the second cooling system, where the second closed mixed cooling circuit contains a second mixed refrigerant, while the second closed mixed cooling circuit does not contain a phase separator; (e) a turboexpander in fluid communication with a first cooling system or a second cooling system, wherein the turboexpander is configured to expand the first chilled feed stream or the second chilled feed stream as an expanded stream; (f) a separator in fluid communication with a turboexpander, where the separator is configured to separate the expanded stream into a vapor head fraction and a liquid bottom fraction; (g) a pipeline for returning at least a portion of the vapor head fraction to the first cooling system or second cooling system; and (h) a compressor at least partially driven by operation obtained from the turboexpander, wherein the compressor is configured to partially compress at least a first mixed refrigerant, a second mixed refrigerant, or a vapor head fraction.

Brief Description of the Figures

[0009] Embodiments of the present invention are described herein with reference to the following figures of drawings, where:

[0010] Figure 1 depicts a dual mixed refrigerant closed system for extracting a liquefied natural gas stream from a gas feed stream in accordance with one embodiment of the present invention;

[0011] FIG. 2 depicts a dual mixed refrigerant closed system comprising a turboexpander, a heavy fraction separator, and a compressor connected to a first cooling system, in accordance with one embodiment of the present invention;

[0012] Figure 3 depicts a dual mixed refrigerant closed system comprising a turboexpander and a heavy fraction separator connected to a first cooling system and a compressor connected to a first closed mixed cooling circuit in accordance with one embodiment of the present invention;

[0013] FIG. 4 depicts a dual mixed refrigerant closed system comprising a turboexpander and a heavy fraction separator connected to a first cooling system and a compressor connected to a second closed mixed cooling circuit, in accordance with one embodiment of the present invention;

[0014] Figure 5 depicts a dual mixed refrigerant closed system comprising a turboexpander, a heavy fraction separator, and a compressor coupled to a second cooling system, in accordance with one embodiment of the present invention;

[0015] FIG. 6 depicts a dual mixed refrigerant closed system comprising a turboexpander and a heavy fraction separator connected to a second cooling system and a compressor connected to a first closed mixed cooling circuit in accordance with one embodiment of the present invention; and

[0016] FIG. 7 shows a dual mixed refrigerant closed system comprising a turboexpander and a heavy fraction separator connected to a second cooling system and a compressor connected to a second closed mixed cooling circuit, in accordance with one embodiment of the present invention.

Detailed description

[0017] The following detailed description of embodiments of the present invention refers to the accompanying drawings. Embodiments are intended to describe various aspects of the present invention in substantial detail to enable one skilled in the art to implement the present invention. Other embodiments may be used and other changes may be made without departing from the scope of the claims. Therefore, the following detailed description cannot be taken in a limiting sense. The scope of the present invention is defined only by the attached claims, together with the full scope of equivalents to which such claims relate.

[0018] The present invention generally relates to methods and systems for liquefying a hydrocarbon-containing gas, thereby forming a methane-containing LNG stream. As described below, these methods and systems can use a mixed mixed refrigerant dual system to facilitate the liquefaction of methane from a hydrocarbon-containing gas. Various embodiments of a dual mixed refrigerant system are described further below in accordance with Figures 1-7.

[0019] Turning now to FIG. 1, a schematic illustration of an LNG extraction apparatus 10 configured in accordance with one or more embodiments of the present invention is provided. The LNG recovery unit 10 may operate to condense and supercool a significant portion of the methane in the feed stream of hydrocarbon-containing feed materials by cooling the gas using the first cooling system 12 and the second cooling system 14. Additional details regarding the configuration and operation of the LNG recovery unit 10, in accordance with various embodiments of the present invention, are described below with reference to Figures 1-7.

[0020] As shown in FIG. 1, a hydrocarbon-containing gas feed stream may first be introduced into the LNG recovery unit 10 through conduit 110, and the hydrocarbon-containing gas may be any suitable hydrocarbon-containing fluid stream, such as, for example, natural gas stream, synthesis gas stream, gas stream from cracking, associated gas from oil production, or a combination thereof. The flow of hydrocarbon-containing gas in conduit 110 may come from a variety of gas sources (not shown), including, but not limited to, a distribution network for natural gas pipelines; a well for hydrocarbon production; installation of unusual gas production; installation for petrochemical processing; coal seam processing plant; an oil refining process unit, such as a catalytic cracking unit with a fluidized bed (FCC) or an oil coke plant; or a heavy oil refinery, such as an oil sands refinery.

[0021] Depending on its source, a hydrocarbon-containing gas may contain various amounts of methane, nitrogen, hydrogen, carbon monoxide, carbon dioxide, sulfur particles and other hydrocarbons. For example, a hydrocarbon-containing gas may contain at least 1, 5, 10, 15 or 25 and / or not more than 99, 95, 90, 80, 70 or 60 molar percent of methane. More specifically, a hydrocarbon-containing gas may contain from 1 to 99, 5 to 95, 10 to 90, 15 to 80, or 25 to 70 molar percent of methane. It should be noted that all molar percentages refer to the total number of moles of hydrocarbon-containing gas.

[0022] In various embodiments, the hydrocarbon-containing gas contains little or no hydrogen. For example, a hydrocarbon-containing gas may contain less than 10, 5, 1, or 0.5 molar percent hydrogen.

[0023] In various embodiments, the hydrocarbon-containing gas may or may not contain a small amount of carbon monoxide. For example, a hydrocarbon-containing gas may contain no more than 20, 10, 5, or 1 molar percent of carbon monoxide.

[0024] In various embodiments, the hydrocarbon-containing gas may contain a small amount of nitrogen or even contain a small amount of it. For example, a hydrocarbon-containing gas may contain no more than 20, 10, 5, or 1 molar percent of nitrogen.

[0025] In various embodiments, the hydrocarbon-containing gas may or may not contain a small amount of carbon dioxide. For example, a hydrocarbon-containing gas may contain no more than 20, 10, 5, or 1 molar percent of carbon dioxide.

[0026] In various embodiments, the hydrocarbon-containing gas may or may not contain a small amount of sulfur-containing compounds, which includes any sulfur-containing compounds. For example, a hydrocarbon-containing gas may contain no more than 20, 10, 5, or 1 molar percent of sulfur-containing compounds.

[0027] In addition, the hydrocarbon-containing gas may contain a certain amount of C ₂ -C ₅ components, which includes their paraffin and olefin isomers. For example, a hydrocarbon-containing gas may contain less than 30, 25, 15, 10, 5, or 2 molar percent of C ₂ -C ₅ components.

[0028] In addition, a hydrocarbon-containing gas may contain a certain amount of C ₆₊ components, which includes hydrocarbon-based compounds having a carbon chain length of at least 6 carbon atoms and their paraffin and olefin isomers. For example, a hydrocarbon-containing gas may contain less than 30, 25, 15, 10, 5, or 2 molar percent of C ₆₊ compounds.

[0029] Furthermore, the hydrocarbon-containing gas may contain a certain amount of impurities, such as, for example, benzene, toluene and xylene (ʺ BTX ʺ). For example, a hydrocarbon-containing gas may contain less than 30, 25, 15, 10, 5, 2, or 1 molar percent of BTX components.

[0030] As shown in FIG. 1, hydrocarbon-containing gas in conduit 110 may first be directed to a pre-treatment zone 16 where one or more undesirable constituents may be removed from the gas before cooling. In one or more embodiments, the pretreatment zone 16 may comprise one or more vapor-liquid separation vessels (not shown) for removing liquid water or hydrocarbon components from the starting components. Optionally, pretreatment zone 16 may include one or more gas removal zones (not shown), such as, for example, an amine unit or molecular sieve, for removing carbon dioxide and / or sulfur compounds from the gas stream in conduit 110.

[0031] Then, the treated gas stream leaving the pre-treatment zone 16 through conduit 112 can be directed to a dehydration unit 18, where substantially all residual water can be removed from the supplied gas stream. The dehydration unit 18 may use any known water removal system, such as, for example, molecular sieve layers. After drying, the gas stream in conduit 114 may have a temperature of at least 5, 10, or 15 ° C and / or not more than 50, 45, or 40 ° C. More specifically, the gas flow in conduit 114 may have a temperature in the range of 5 to 50 ° C, 10 to 45 ° C, or 15 to 40 ° C. In addition to this, or alternatively, the gas flow in conduit 114 may have a pressure of at least 1.5, 2.5, 3.5, or 4.0 and / or not more than 9.0, 8.0, 7 5 or 7 MPa. More specifically, the gas flow in conduit 114 may have a pressure in the range of 1.5 to 9.0, 2.5 to 8.0, 3.5 to 7.5, or 4.0 to 7.0 MPa.

[0032] As shown in FIG. 1, a hydrocarbon containing feed stream in conduit 114 may be introduced into a first cooling passage 22 in a first cooling zone 20 of a first cooling system 12. As further described below, the first cooling system 12 may be any heat exchanger or a series of heat exchangers operating to cool and at least partially condense the supplied gas stream in conduit 114 by indirect heat exchange with the first mixed refrigerant. In one or more embodiments, the first cooling system 12 may be a brazed aluminum heat exchanger comprising a plurality of cooling and heating passages (e.g., cores) located therein to facilitate indirect heat exchange between one or more process streams and one or more refrigerant streams.

[0033] The hydrocarbon-containing gas stream passing through the cooling passage 22 of the first cooling zone 20 can be cooled by indirect heat exchange with the first mixed refrigerant in the refrigerant heating passage 24, which is described in further detail below. As used herein, the term “mixed refrigerant” refers to a refrigerant composition containing two or more components.

[0034] The gas flow in conduit 116 may then be introduced into the second cooling passage 28 in the second cooling zone 26 of the first cooling system 12. In various embodiments, a hydrocarbon containing gas stream passing through the cooling passage 28 of the second cooling zone 26 may be cooled by indirect heat exchange with the first mixed refrigerant in the refrigerant heating passage 30, which is described in further detail below. In certain embodiments, at least a portion of the methane component in the feed gas stream may condense from the vapor phase during cooling, thereby creating a cooled two-phase fluid stream in conduit 118. Alternatively, in certain embodiments, the second cooling zone 26 will not condense the methane component in the feed gas stream, and the resulting fluid stream in line 118 will be a single-phase vapor stream.

[0035] The gas flow in conduit 118 may then be introduced into the third cooling passage 34 in the third cooling zone 32 of the first cooling system 12. In certain embodiments, a hydrocarbon containing gas stream passing through the cooling passage 34 of the third cooling zone 32 may be cooled by indirect heat exchange with the first mixed refrigerant in the refrigerant heating passage 36, which is described in further detail below. In various embodiments, at least a portion of the methane component in the feed gas stream may condense from the vapor phase to produce a cooled biphasic fluid stream in conduit 120. In one or more embodiments, at least 5, 10, 25 , 50, 60, 70, 80, or 90 percent of the total methane introduced into the first cooling system 12 may condense when leaving the third cooling zone 32. Alternatively, in certain embodiments, the third cooling zone 32 will not condense the methane component in the feed gas stream, and the resulting fluid stream in line 120 will be a single-phase vapor stream.

[0036] As shown in FIG. 1, a hydrocarbon containing feed stream in conduit 120 may then be introduced into the cooling passage 40 in a single cooling zone 38 of the second cooling system 14. As further described below, the second cooling system 14 may be a heat exchanger operating to condense and supercool the supplied gas stream in conduit 120 by indirect heat exchange with a second mixed refrigerant. In one or more embodiments, the second cooling system 14 may be a brazed aluminum heat exchanger comprising a plurality of cooling and heating passages (e.g., cores) located therein to facilitate indirect heat exchange between one or more process streams and one or more refrigerant streams .

[0037] Although not shown in Figures 1-7, in various embodiments, the first cooling system 12 and the second cooling system 14 may be contained in the same heat exchanger, and each of the above zones (20, 26, 32 and 38) The cooling can be connected in series in a single core inside this heat exchanger. In addition, although Figures 1-7 depict physical pipelines between the cooling zones (20, 26, 32 and 38), one skilled in the art will readily notice that there may be embodiments where no physical pipelines exist between the zones (20, 26, 32 and 38) cooling, in particular, in embodiments where the cooling zones (20, 26, 32 and 38) are connected in series.

[0038] The supplied hydrocarbon containing gas stream passing through the cooling passage 40 of the cooling zone 38 can be condensed and supercooled by indirect heat exchange with a second mixed refrigerant in the heating passage 42 for the refrigerant, which is described in further detail below.

[0039] When it leaves the second cooling system 14, the supercooled feed stream in conduit 122 can then expand by passing through an expansion device 44 in which the flow pressure may decrease. The expansion device 44 may include any expansion device, such as, for example, a Joule-Thomson valve or a hydraulic turbine. Although it is illustrated in FIG. 1 as containing a single device 44, it should be understood that any suitable number of expansion devices may be used. In certain embodiments, the expansion may be substantially isoenthalpic expansion or isentropic expansion. As used herein, the term “substantially isoenthalpic” refers to the stage of expansion or instant expansion, carried out in such a way that less than 1 percent of the total work generated during expansion is transferred from the fluid to the environment. As used herein, “isentropic” expansion refers to the stage of expansion or instant expansion, in which most or substantially all of the work generated during expansion is transferred to the environment.

[0040] The expanded flow in line 124 may be controlled by valve 46. The cooled stream leaving valve 46 through line 126 may be an LNG enriched product. As used herein, “Enriched LNG” means that this particular composition contains at least 50 molar percent of methane. The LNG-enriched product in line 126 may have a temperature lower than -120, -130, -140, or -145 ° C and / or higher than -195, -190, -180 or -165 ° C. More specifically, the LNG-enriched product in conduit 126 can have a temperature in the range of -120 to -195 ° C, -130 to -190 ° C, -140 to -180 ° C, or -145 to -165 ° C.

[0041] Referring again to FIG. 1, here, the first cooling system 12 and the first closed mixed cooling circuit are described in further detail below. As shown in FIG. 1, the first cooling system 12 comprises three cooling zones (20, 26 and 32), where the first closed mixed cooling circuit is located at least partially in them.

[0042] The first closed mixed refrigeration circuit contains a first mixed refrigerant, and is shown in FIG. 1 as follows. When the refrigerant leaves the refrigerant heating passage 24 in the first cooling zone 20, the gaseous first mixed refrigerant in line 128 is transferred to the compressor system 48 comprising a first compressor stage 54, a second compressor stage 52 and a third compressor stage 50.

[0043] In various embodiments, the gaseous first mixed refrigerant in line 128 may be at a pressure of at least 1.5, 2.0, or 2.7 MPa and / or not more than 5.0, 4.0 , or 3.5 MPa. More specifically, the gaseous first mixed refrigerant in conduit 128 may be at a pressure in the range of 1.5 to 5.0 MPa, 2.0 to 4.0 MPa, or 2.7 to 3.5 MPa. In addition to this or alternatively, the gaseous first mixed refrigerant in conduit 128 may be at a temperature lower than 50, 35, or 25 ° C and / or higher than -40, -30, or -20 ° C. More specifically, the gaseous first mixed refrigerant in line 128 can be at a temperature in the range of −40 to 50 ° C, −30 to 35 ° C, or −20 to 25 ° C.

[0044] Although it is depicted as containing only three stages in FIG. 1, one skilled in the art would easily have noticed that the compressor 48 can be modified so that it contains more or less stages, if necessary. In various embodiments, the compressor system 48 may comprise an axial compressor, a centrifugal compressor, a reciprocating compressor, a screw compressor, or a combination thereof. In addition, the compressor system 48 may be driven by a steam turbine, gas turbine, electric motor, or combinations thereof.

[0045] In various embodiments, the refrigerant may flow through the seals of the compressor 48. In such embodiments, instead of losing the refrigerant that leaks, a method of extracting sealing gas can be used that removes at least a portion of the refrigerant and returns it to the cooling circuit. . A method for recovering sealing gas is described in US Pat. No. 8066023, which is incorporated herein by reference in its entirety. For example, compressor 48 may be connected to a venturi tube (not shown) to hold any sealing gas leaking from the compressor.

[0046] A gaseous first mixed refrigerant in conduit 128 may be introduced into the third compressor stage 50. In various embodiments, the third compressor stage 50 may compress the gaseous first mixed refrigerant to a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6, 3 MPa. More specifically, the third stage of the compressor 50 can compress the gaseous first mixed refrigerant to a pressure in the range of 2.5 to 8.0 MPa, 4.0 to 7.0 MPa, or 4.8 to 6.3 MPa.

[0047] The compressed first mixed refrigerant is transferred through line 130 to the outlet cooler 56, where the stream can be cooled to ambient temperature and completely condensed by indirect heat exchange with an external cooling medium (eg, cooling water or air). As used herein, “fully condensed” means that the identified stream contains less than 1.0 molar percent of vapor. In one or more embodiments, the fully condensed stream may contain less than 0.5, 0.1, 0.05, or 0.001 molar percent of vapor. In various embodiments, the first mixed refrigerant should be a liquid at a pressure of release from the cooler.

[0048] When it leaves the outlet cooler 56 through line 132, the fully condensed first mixed refrigerant is introduced into the cooling passage 58 in the first cooling zone 20. In various embodiments, the fully condensed first mixed refrigerant in line 132 may be at a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6, 3 MPa. More specifically, the fully condensed first mixed refrigerant in line 132 may be at a pressure in the range of 2.5 to 8.0 MPa, 4.0 to 7.0 MPa, or 4.8 to 6.3 MPa. In addition to this or alternatively, the fully condensed first mixed refrigerant in line 132 can reach ambient temperature.

[0049] In the cooling passage 58, the fully condensed first mixed refrigerant may be supercooled by indirect heat exchange with the first mixed refrigerant in the refrigerant heating passage 24, which is further described below.

[0050] When the flow leaves the cooling passage 58 through conduit 134, at least a portion of the flow may be directed through conduit 136 to an expansion device 60, where the flow pressure may decrease, while it is cooled and, in some embodiments, the refrigerant stream is at least least partially evaporates. The expansion device 60 may include any suitable expansion device, such as, for example, a Joule-Thomson valve or a hydraulic turbine. Although it is illustrated in FIG. 1 as containing a single device 60, it should be understood that any suitable number of expandable devices can be used. In certain embodiments, the expansion may be essentially isoenthalpic expansion or isentropic expansion.

[0051] Prior to expansion, the fully condensed first mixed refrigerant in line 136 may be at a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6 , 3 MPa. More specifically, the fully condensed first mixed refrigerant in line 136 can be at a pressure in the range of 2.5 to 8.0, 4.0 to 7.0, or 4.8 to 6.3 MPa. In addition to this or alternatively, the fully condensed first mixed refrigerant in line 136 may be at a temperature lower than 30, 25 or 15 ° C and / or higher than -40, -30 or -5 ° C. More specifically, the fully condensed first mixed refrigerant in line 136 can be at a temperature in the range of −40 to 30 ° C, −30 to 25 ° C, or −5 to 15 ° C.

[0052] In various embodiments, the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step. As used herein, “phase separation” includes the separation of a two-phase stream, typically containing a liquid and vapor phase, into its corresponding phase.

[0053] The expanded first mixed refrigerant is introduced into the refrigerant heating passage 24 through line 138, where the expanded first mixed refrigerant can be vaporized to provide cooling in the first cooling zone 20.

[0054] In various embodiments, the expanded first mixed refrigerant in line 138 may comprise less than 5, 3, 1, 0.5, or 0.1 molar percent of the vapor phase. In addition, in certain embodiments, the expanded first mixed refrigerant in line 138 may be at a pressure of at least 1.5, 2.0, or 2.7 MPa and / or not more than 5.0, 4.0, or 3.5 MPa. More specifically, the expanded first mixed refrigerant in line 138 may be at a pressure in the range of 1.5 to 5.0 MPa, 2.0 to 4.0 MPa, or 2.7 to 3.5 MPa. In addition to this or alternatively, the expanded first mixed refrigerant in line 138 may be at a temperature lower than 30, 25, or 15 ° C and / or higher than -40, -30, or -5 ° C. More specifically, the expanded first mixed refrigerant in conduit 138 may be at a temperature in the range of -40 to 30 ° C, -30 to 25 ° C, or -5 to 15 ° C.

[0055] The vaporized gaseous first mixed refrigerant leaves the heating passage 24 for the refrigerant through line 128, as described above.

[0056] Referring again to FIG. 1, at least a portion of the fully condensed first mixed refrigerant in line 134 is directed to a cooling passage 62 in a second cooling zone 26. In the cooling passage 62, the fully condensed first mixed refrigerant can be further cooled by indirect heat exchange with the first mixed refrigerant in the heating passage for the refrigerant 30, which is further described below.

[0057] When the flow leaves the cooling passage 62 through conduit 140, at least a portion of the flow may be directed through conduit 142 to expansion device 64, where the flow pressure may decrease, while cooling and, in some embodiments, at least partially evaporating refrigerant stream. The expansion device 64 may include any suitable expansion device, such as, for example, a Joule-Thomson valve or a hydraulic turbine. Although it is illustrated in FIG. 1 as containing a single device 64, it should be understood that any suitable number of expandable devices can be used. In certain embodiments, the expansion may be substantially isoenthalpic expansion or isentropic expansion. In various embodiments, the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step.

[0058] Prior to expansion, the fully condensed first mixed refrigerant in line 142 may be at a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6 , 3 MPa. More specifically, the fully condensed first mixed refrigerant in line 142 may be at a pressure in the range of 2.5 to 8.0, 4.0 to 7.0, or 4.8 to 6.3 MPa. In addition to this or alternatively, the fully condensed first mixed refrigerant in line 142 may be at a temperature lower than 0, -10, or -25 ° C and / or higher than -100, -75 or -50 ° C. More specifically, the fully condensed first mixed refrigerant in conduit 142 may be at a temperature in the range of −100 to 0 ° C, −75 to −10 ° C, or −50 to −25 ° C.

[0059] The expanded first mixed refrigerant is introduced into the heating passage 30 for the refrigerant through line 144, where the expanded first mixed refrigerant is vaporized to provide cooling in the second cooling zone 26. In various embodiments, the expanded first mixed refrigerant in conduit 144 may comprise less than 5, 4, 3, 2, 1, or 0.1 molar percent of the vapor phase. Furthermore, in certain embodiments, the expanded first mixed refrigerant in conduit 144 may be at a pressure of at least 0.3, 0.5, or 0.65 MPa and / or not more than 2.0, 1.7, or 1.4 MPa. More specifically, the expanded first mixed refrigerant in conduit 144 may be at a pressure in the range of 0.3 to 2.0 MPa, 0.5 to 1.7 MPa, or 0.65 to 1.4 MPa. In addition to this or alternatively, the expanded first mixed refrigerant in conduit 144 may be at a temperature lower than 0, -10, or -25 ° C and / or higher than -100, -75 or -50 ° C. More specifically, the expanded first mixed refrigerant in conduit 144 may be at a temperature in the range of −100 to 0 ° C, −75 to −10 ° C., or −50 to −25 ° C.

[0060] The vaporized gaseous first mixed refrigerant leaves the heating passage 30 for the refrigerant through conduit 146 and can be introduced into the second stage of compressor 52. In various embodiments, the gaseous first mixed refrigerant in conduit 146 may be at a pressure of at least 0.3 , 0.5 or 0.65 MPa and / or not more than 2.0, 1.7 or 1.4 MPa. More specifically, the gaseous first mixed refrigerant in line 146 may be at a pressure in the range of 0.3 to 2.0 MPa, 0.5 to 1.7 MPa, or 0.65 to 1.4 MPa. In addition to this or alternatively, the gaseous first mixed refrigerant in line 146 may be at a temperature lower than 30, 25 or 15 ° C and / or higher than -40, -30 or -5 ° C. More specifically, the gaseous first mixed refrigerant in line 146 may be at a temperature in the range of −40 to 30 ° C, −30 to 25 ° C, or −5 to 15 ° C.

[0061] In various embodiments, the second compressor stage 52 may compress the gaseous first mixed refrigerant to a pressure of at least 1.5, 2.0, or 2.7 MPa and / or not more than 5.0, 4.0 or 3.5 MPa. More specifically, the second stage 52 of the compressor can compress the gaseous first mixed refrigerant to a pressure in the range from 1.5 to 5.0 MPa, from 2.0 to 4.0 MPa, or from 2.7 to 3.5 MPa.

[0062] The compressed first mixed refrigerant from the second compressor stage 52 is transferred via line 148 to an intercooler 66, where the stream can be cooled by indirect heat exchange with an external cooling medium (eg, cooling water or air). When it leaves the intercooler 66 through conduit 150, the compressed stream in conduit 150 may be introduced into conduit 128, where it may be sent for further compression to the third compressor stage 50, as described above.

[0063] Referring again to FIG. 1, at least a portion of the fully condensed first mixed refrigerant in line 140 is directed to a cooling passage 68 in a third cooling zone 32. In the cooling passage 68, the fully condensed first mixed refrigerant can be further subcooled by indirect heat exchange with the first mixed refrigerant in the heating passage 36 for the refrigerant, which is further described below.

[0064] When it leaves the cooling passage 68 through conduit 152, the cooled stream may be directed to an expansion device 70 where the pressure of the stream may decrease, while cooling and at least partially evaporating the refrigerant stream. The expansion device 70 may include any suitable expansion device, such as, for example, a Joule-Thomson valve or a hydraulic turbine. Although it is illustrated in FIG. 1 as containing a single device 70, it should be understood that any suitable number of expandable devices can be used. In certain embodiments, the expansion may be substantially isoenthalpic expansion or isentropic expansion. In various embodiments, the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step.

[0065] Prior to expansion, the fully condensed first mixed refrigerant in conduit 152 may be at a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6 , 3 MPa. More specifically, the fully condensed first mixed refrigerant in line 152 may be at a pressure in the range of 2.5 to 8.0, 4.0 to 7.0, or 4.8 to 6.3 MPa. In addition to this or alternatively, the fully condensed first mixed refrigerant in conduit 152 may be at a temperature lower than −20, −40, or −60 ° C. and / or higher than −120, −90, or −75 ° C. More specifically, the fully condensed first mixed refrigerant in conduit 152 may be at a temperature in the range of −120 to −20 ° C., −90 to −40 ° C., or −75 to −60 ° C.

[0066] The expanded first mixed refrigerant is introduced into the refrigerant heating passage 36 through line 154, where the expanded first mixed refrigerant is vaporized to provide cooling in the third cooling zone 32. In various embodiments, the expanded first mixed refrigerant in conduit 154 may comprise less than 10, 7, 6, 4, 2, 1, or 0.5 mole percent of the vapor phase. Furthermore, in certain embodiments, the expanded first mixed refrigerant in conduit 154 may be at a pressure of at least 0.1, 0.15, or 0.2 MPa and / or not more than 2.0, 1.5, or 0.5 MPa. More specifically, the expanded first mixed refrigerant in line 154 may be at a pressure in the range of 0.1 to 2.0 MPa, 0.15 to 1.5 MPa, or 0.2 to 0.5 MPa. In addition to this or alternatively, the expanded first mixed refrigerant in conduit 154 may be at a temperature lower than -20, -40 or -60 ° C and / or higher than -120, -90 or -75 ° C. More specifically, the expanded first mixed refrigerant in conduit 154 may be at a temperature ranging from −120 to −20 ° C., −90 to −40 ° C., or −75 to −60 ° C.

[0067] The vaporized gaseous first mixed refrigerant leaves the heating passage 36 for the refrigerant through line 156 and can be introduced into the first stage 54 of the compressor. In various embodiments, the gaseous first mixed refrigerant in line 156 may be at a pressure of at least 0.1, 0.15, or 0.2 MPa and / or not more than 2.0, 1.5, or 0.5 MPa More specifically, the gaseous first mixed refrigerant in line 156 may be at a pressure in the range of 0.1 to 2.0 MPa, 0.15 to 1.5 MPa, or 0.2 to 0.5 MPa. In addition to this or alternatively, the gaseous first mixed refrigerant in line 156 may be at a temperature lower than 0, -10 or -25 ° C and / or higher than -100, -75 or -50 ° C. More specifically, the gaseous first mixed refrigerant in line 156 may be at a temperature in the range of −100 to 0 ° C., −75 to −10 ° C., or −50 to −25 ° C.

[0068] When it leaves the first compressor stage 54 through conduit 158, the compressed stream in conduit 158 can be introduced into conduit 146, where it can be sent for further compression to second compressor stage 52B and third compressor stage 50 as described above. In various embodiments, the first compressor stage 54 may compress the gaseous first mixed refrigerant to a pressure of at least 0.3, 0.5, or 0.65 MPa and / or not more than 2.0, 1.7, or 1, 4 MPa. More specifically, the first compressor stage 54 may compress the gaseous first mixed refrigerant to a pressure in the range of 0.3 to 2.0 MPa, 0.5 to 1.7 MPa, or 0.65 to 1.4 MPa.

[0069] In various embodiments, and as shown in FIG. 1, the first cooling system 12 and the first closed mixed cooling circuit do not contain a phase separator. As used herein, a “phase separator” is understood to encompass any device designed solely to separate a partially condensed stream into liquid and vapor fractions. As a consequence of this, it should not contain, for example, vacuum drums and surge drums.

[0070] In certain embodiments, pipelines 136, 138, 142, 144, 152 and 154 of FIG. 1, when physically present, may be located outside their respective cooling zones (20, 26, and 32). In such embodiments, pipelines 136, 138, 142, 144, 152 and 154 could be located outside of heat exchangers or outside those heat exchangers that contain respective cooling zones (20, 26, and 32).

[0071] The first mixed refrigerant may contain two or more components selected from the group consisting of nitrogen, methane, ethylene, ethane, propylene, propane, isobutane, n-butane, isopentane, n-pentane, and combinations thereof. In some embodiments, implementation, the first mixed refrigerant may contain at least two compounds selected from the group consisting of hydrocarbons containing from 2 to 4 carbon atoms. In certain embodiments, the first mixed refrigerant may have a saturation pressure between 2.5 and 5.65 MPa at about ambient temperature.

[0072] In some embodiments of the present invention, it may be desirable to adjust the composition of the first mixed refrigerant so as to alter its cooling curve and thus its cooling potential. Such a modification can be used in order to correspond, for example, to changes in composition and / or flow rate, for the feed gas stream introduced into the LNG recovery unit 10. In one embodiment, the composition of the first mixed refrigerant can be adjusted so that the heating curve of the evaporating refrigerant closely matches the cooling curve of the supplied gas stream and warm refrigerant. One method for such curve matching is described in detail in US Pat. No. 4,033,735, the disclosure of which is incorporated herein by reference in its entirety.

[0073] Turning again to FIG. 1, here a second cooling system 14 and a second closed mixed cooling circuit are described in further detail. As shown in FIG. 1, the second cooling system 14 comprises a single cooling zone 38, where the second closed mixed cooling circuit is at least partially located therein. As used herein, a “single cooling zone” means that the system contains only one zone where the feed stream is cooled by indirect heat exchange with a single cooling medium. In such embodiments, the identifiable system will not contain any other cooling zones. In certain embodiments, a single cooling medium may comprise an expanded first mixed refrigerant or an expanded second mixed refrigerant. In various embodiments, the second cooling system 12 comprises a single cooling zone, consists essentially of a single cooling zone, or consists of a single zone.

[0074] The second closed mixed cooling circuit comprises a second mixed refrigerant and is shown in FIG. 1 as follows. When the refrigerant leaves the refrigerant heating passage 42 in the cooling zone 38, the gaseous second mixed refrigerant in conduit 160 is transferred to a compressor system 72 comprising a first compressor stage 74 and a second compressor stage 76. In various embodiments, compressor 72 may be configured to extract a seal gas, as previously described with respect to compressor 48. Thus, in certain embodiments, compressor 72 may include a venturi (not shown) designed to hold the seal gas flowing out of the compressor. .

[0075] In various embodiments, the gaseous second mixed refrigerant in conduit 160 is at a pressure in the range of 0.1, 0.15, or 0.2 MPa and / or not more than 2.0, 1.5, or 0.5 MPa . More specifically, the gaseous second mixed refrigerant in conduit 160 may be at a pressure in the range of 0.1 to 2.0 MPa, 0.15 to 1.5 MPa, or 0.2 to 0.5 MPa. In addition to this or alternatively, the gaseous second mixed refrigerant in conduit 160 is at a temperature lower than -20, -40 or -60 ° C and / or higher than -120, -90 or -75 ° C. More specifically, the gaseous second mixed refrigerant in conduit 160 may be at a temperature in the range of -120 to -20 ° C, -90 to -40 ° C, or -75 to -60 ° C.

[0076] Although it is depicted in FIG. 1 as having only two stages, one skilled in the art would easily see that the compressor 72 can be modified so that it contains more or fewer stages, if necessary. In various embodiments, the compressor system 72 may comprise an axial compressor, a centrifugal compressor, a reciprocating compressor, a screw compressor, or a combination thereof. In addition, the compressor system 72 may be driven by a steam turbine, gas turbine, electric motor, or combinations thereof.

[0077] A gaseous second mixed refrigerant in conduit 160 is introduced into the first compressor stage 74 and then transferred through conduit 162 to intercooler 78, where the stream can be cooled to ambient temperature by indirect heat exchange with an external cooling medium (eg, cooling water) or air). In various embodiments, the first compressor stage 74 may compress the gaseous second mixed refrigerant to a pressure of at least 0.3, 0.5, or 0.65 MPa and / or not more than 3.0, 2.5, or 2, 0 MPa. More specifically, the first compressor stage 74 may compress the gaseous second mixed refrigerant to a pressure in the range of 0.3 to 3.0 MPa, 0.5 to 2.5 MPa, or 0.65 to 2.0 MPa.

[0078] The cooled second mixed refrigerant may then be introduced into the second compressor stage 76 through line 164, where the second mixed refrigerant is further compressed. In various embodiments, the second stage of compressor 76 may compress the gaseous second mixed refrigerant to a pressure of at least 2.5, 4.0, or 4.8 and / or not more than 8.0, 7.0, or 6.0 MPa More specifically, the second stage of the compressor 76 can compress the gaseous second mixed refrigerant to a pressure in the range of 2.5 to 8.0 MPa, 4.0 to 7.0 MPa, or 4.8 to 6.0 MPa.

[0079] The compressed second mixed refrigerant is then introduced into the outlet cooler 80 via line 166, where the stream can be further cooled to ambient temperature by indirect heat exchange with an external cooling medium (eg, cooling water or air).

[0080] The compressed second mixed refrigerant in line 168 is then introduced into the cooling passage 82 in the first cooling zone 20 of the first cooling system 12. In various embodiments, the compressed second mixed refrigerant in conduit 168 may be at a pressure of at least 2.5, 4.0, or 4.8 MPa and / or not more than 8.0, 7.0, or 6.0 MPa More specifically, the compressed second mixed refrigerant in conduit 168 may be at a pressure in the range of 2.5 to 8.0 MPa, 4.0 to 7.0 MPa, or 4.8 to 6.0 MPa. In addition, or alternatively, the compressed second mixed refrigerant in conduit 168 may be at or near ambient temperature.

[0081] In the cooling passage 82, the second mixed refrigerant may be further cooled by indirect heat exchange with the first mixed refrigerant in the heating passage 24 for the refrigerant. At the same time, in the cooling passage 82, the second mixed refrigerant can be cooled to a temperature below the dew point of the refrigerant mixture.

[0082] The cooled second mixed refrigerant in line 170 is then introduced into the cooling passage 84 in the second cooling zone 26 of the first cooling system 12. In the cooling passage 84, the second mixed refrigerant may be further cooled by indirect heat exchange with the first mixed refrigerant in the heating passage 30 for the refrigerant. At the same time, in the cooling passage 84, the second mixed refrigerant can be cooled to a temperature below the dew point of the refrigerant mixture.

[0083] The cooled second mixed refrigerant in line 172 is then introduced into the cooling passage 86 in the third cooling zone 32 of the first cooling system 12. In the cooling passage 86, the second mixed refrigerant may be further cooled by indirect heat exchange with the first mixed refrigerant in the heating passage 36 for the refrigerant. At the same time, in the cooling passage 86, the second mixed refrigerant may be cooled to a temperature below the boiling point of the mixture of refrigerants.

[0084] When it leaves the first cooling system 12 through line 174, the second mixed refrigerant in line 174 is completely condensed. The fully condensed second mixed refrigerant in line 174 may then be introduced into the cooling passage 88 in the cooling zone 38 of the second cooling system 14.

[0085] When it leaves the cooling passage 88 through conduit 176, the supercooled second mixed refrigerant stream may be directed to an expansion device 90, where the pressure may decrease, while cooling and evaporating the refrigerant stream. Prior to expansion, the fully condensed second mixed refrigerant in line 176 may be at a pressure of at least 2.5, 4.0 or 4.8 MPa and / or not more than 8.0, 7.0 or 6.0 MPa . More specifically, the fully condensed second mixed refrigerant in line 176 may be at a pressure in the range of 2.5 to 8.0, 4.0 to 7.0, or 4.8 to 6.0 MPa. In addition to this or alternatively, the fully condensed second mixed refrigerant in line 176 may be at a temperature lower than -120, -130, -140 or -145 ° C and / or higher than -195, -190, -180 or -165 ° C. More specifically, the fully condensed second mixed refrigerant in line 176 can be at a temperature ranging from -120 to -195 ° C, from -130 to -190 ° C, from -140 to -180 ° C, or from -145 to -165 ° C.

[0086] The expansion device 90 may include any suitable expansion device, such as, for example, a Joule-Thomson valve or a hydraulic turbine. Although it is illustrated in FIG. 1 as containing a single device 90, it should be understood that any suitable number of expansion devices can be used. In certain embodiments, the expansion may be substantially isoenthalpic expansion or isentropic expansion.

[0087] The expanded flow in conduit 178 may be controlled by valve 92. In various embodiments, the expanded flow in conduit 178 may comprise less than 15, 10, 8, 6, 2, or 1 molar percent of vapor phase. In addition, in certain embodiments, the expanded flow in conduit 178 may be at a pressure of at least 0.3, 0.5, or 0.65 MPa and / or not more than 3.0, 2.0, or 1, 4 MPa. More specifically, the expanded flow in conduit 178 may be at a pressure in the range of 0.3 to 3.0 MPa, 0.5 to 2.0 MPa, or 0.65 to 1.4 MPa. In addition to this or alternatively, the expanded flow in conduit 178 may be at a temperature lower than -120, -130, -140 or -145 ° C and / or higher than -195, -190, -180 or -165 ° C. More specifically, the expanded flow in conduit 178 can be at a temperature ranging from -120 to -195 ° C, from -130 to -190 ° C, from -140 to -180 ° C, or from -145 to -165 ° C .

[0088] The expanded second mixed refrigerant in line 180 is then introduced into the refrigerant heating passage 42, where the expanded second mixed refrigerant is vaporized to cool the cooling zone 38. In various embodiments, the expanded stream in conduit 180 may comprise less than 15, 10, 8, 6, or 2 molar percent of the vapor phase. In one or more embodiments, the expanded second mixed refrigerant in line 180 may be introduced at pressures in the range 0.1, 0.15, or 0.2 MPa and / or not more than 2.0, 1.5, or 0.5 MPa. . More specifically, the expanded second mixed refrigerant in line 180 can be introduced at pressures ranging from 0.1 to 2.0 MPa, from 0.15 to 1.5 MPa, or from 0.2 to 0.5 MPa.

[0089] In certain embodiments, pipelines 174, 176, 178, and 180 may be located outside of cooling zone 38. In such embodiments, pipelines 174, 176, 178, and 180 may be located outside of a heat exchanger that includes a cooling zone 38.

[0090] The gaseous second mixed refrigerant in conduit 160 is then compressed and recycled to the method described above. In various embodiments, the fully condensed second mixed refrigerant is not subjected to phase separation prior to or after the expansion step.

[0091] In various embodiments, and as shown in FIG. 1, the second cooling system 14 and the second closed mixed cooling circuit do not contain a phase separator.

[0092] The second mixed refrigerant may contain two or more components selected from the group consisting of nitrogen, methane, ethylene, ethane, propylene, propane, isobutane, n-butane, isopentane, n-pentane, and combinations thereof. In some embodiments, the implementation, the second mixed refrigerant may contain at least two compounds selected from the group consisting of nitrogen and hydrocarbons containing from 1 to 3 carbon atoms. In various embodiments, the second mixed refrigerant will have a boiling point that is lower than the boiling point of the first mixed refrigerant at a given pressure. In certain embodiments, the second mixed refrigerant may have a saturation pressure between 2.5 and 6.1 MPa at temperatures between -60 and -75 ° C.

[0093] In some embodiments, the implementation of the present invention, it may be desirable to adjust the composition of the second mixed refrigerant, so as to change its cooling curve and, therefore, its cooling potential. Such a modification can be used in order to correspond, for example, to a change in composition and / or flow rate for the feed gas stream introduced into the LNG recovery unit 10. In one embodiment, the composition of the second mixed refrigerant can be adjusted so that the heating curve of the evaporating refrigerant closely matches the cooling curve of the gas and warm refrigerant feed stream.

[0094] It should be noted that the pipelines depicted between the cooling zones (20, 26, 32, and 38) of FIG. 1 are shown for illustrative purposes only and, in certain embodiments, the physical pipeline may not be present where each the pipeline is shown in Fig.1.

[0095] While FIG. 1 depicts one embodiment of the present methods and systems, other embodiments are contemplated, such as those depicted in FIGS. 2-7, they may include a turboexpander 94, a compressor 96 connected in operation condition with turboexpander 94, and separator 98 heavy fractions. It should be noted that all common system components located in Figures 1-7, all of them are marked accordingly using the same numbers. For example, both the first cooling system 12 and the second cooling system 14 are consistently indicated in Figures 1-7. In addition, the system components in Figures 1-7 are expected to function in the same or substantially similar manner unless otherwise indicated. The only difference between Figures 1-7 is that the pipelines on them are indicated in accordance with their respective figure and embodiment. For example, the corresponding pipelines in FIG. 2 are labeled 2XX, while the corresponding pipelines in FIG. 3 are labeled 3XX (where ʺXʺ is a number). The pipelines in Figures 1-7 function in the same way everywhere (i.e., transferring the flow corresponding to them), unless otherwise indicated.

[0096] FIG. 2 illustrates an LNG extraction unit 10 that includes a turboexpander 94, operatively connected through a pipe 220 to a third cooling zone 32 of a first cooling system 12. A turbo expander is further described in US Pat. No. 6,367,286, which is incorporated herein by reference in its entirety.

[0097] As shown in FIG. 2, at least a portion of the hydrocarbon-containing gas stream passing through the cooling passage 34 of the third cooling zone 32 can be routed through a pipe 220 to a turboexpander 94, where it can expand as a two-phase stream. As a result of expansion, the temperature of the instantly expanded or expanded fluid flow in the pipe 222 may be at least 2, 5 or 10 ° C and / or not more than 50, 40 or 30 ° C lower than the temperature of the stream in the pipe 220. In addition, the pressure of the instantaneously expanded or expanded fluid flow in the pipe 222 may be at least 0.1, 0.2 or 0.3 and / or not more than 5.0, 4.0 or 3 , 0 MPa lower than flow pressure in conduit 220. In certain embodiments, the expansion may be substantially isentropic . Although not shown in FIG. 2, a vacuum drum may be in fluid communication between the turboexpander 94 and the third cooling zone 32 in certain embodiments.

[0098] In addition, the turboexpander 94 is connected to the compressor 96 through the shaft 95. The compressor 96 may be at least partially driven by operation obtained from the turboexpander 94. As described below, the compressor 96 is configured to at least partially compressing the overhead coming from separator 98. In various embodiments, compressor 96 may comprise an axial compressor, a centrifugal compressor, a reciprocating compressor, a screw compressor, or a combination thereof. In addition, the compressor 96 may be driven by a steam turbine, gas turbine, electric motor, or a combination thereof.

[0099] In various embodiments, the compressor 96 may be configured to recover the seal gas, as previously described with respect to the compressor 48. Thus, in certain embodiments, the compressor 96 may include a venturi (not shown) designed to hold the seal gas leaking from the compressor.

[0100] As shown in FIG. 2, the expanded two-phase stream in line 222 is directed to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane depleted (line 224) and a vapor head fraction that is rich in methane (line 226) . As used herein, “methane depleted” and “methane enriched” refer to the methane content of the separated components with respect to the methane content of the starting component from which the separated components are obtained. Thus, the methane-enriched component contains a higher molar percentage of methane than the component from which it is derived, while the methane-depleted component contains a lower molar percentage of methane than the component from which it is derived. In this case, the methane-depleted bottom stream contains a lower molar percentage of methane compared to the stream from line 222, while the methane-rich head stream contains a higher molar percentage of methane compared to the stream from line 222. The amounts of methane-depleted bottom stream and the methane-rich overhead stream may vary depending on the hydrocarbon-containing gas content and operating conditions of the separation vessel 98.

[0101] The methane-depleted bottom stream in conduit 224 can be in the form of a liquid, and it can contain most compounds having six or more carbon atoms originally in the stream in conduit 222. For example, the methane-depleted bottom stream in conduit 224 may contain, by at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 222.

[0102] Methane Enriched the vapor head stream in conduit 226 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 226 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched steam overhead stream in conduit 226 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in line 226 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent of the methane initially present in the stream from line 222.

[0103] The separation vessel 98 may be any suitable vapor-liquid separation vessel, and it may have any number of real or theoretical separation stages. In one or more embodiments, the separation vessel 98 may comprise a single separation stage, while in other embodiments, the separation vessel 98 may comprise from 2 to 10, 4 to 20, or 6 to 30 real or theoretical separation stages. When the separation vessel 98 is a multi-stage separation vessel, any suitable type of column interior equipment, such as dehumidifiers, mesh nozzle, steam-liquid contact plates, disordered nozzle and / or structured nozzle, can be used to facilitate heat and / or mass transfer between steam and liquid flows. In some embodiments, when the separation vessel 98 is a single-stage separation vessel, a small amount of column equipment may be used or not used at all.

[0104] In various embodiments, the separation vessel 98 may operate at a pressure of at least 1.5, 2.5, 3.5, or 4.5 and / or 9.0, 8.0, 7.0, or 6.0 MPa. More specifically, the separation tank 98 can operate at a pressure in the range from 1.5 to 9.0, from 2.5 to 8.0, from 3.5 to 7.0, or from 4.5 to 6.0 MPa.

[0105] As one skilled in the art will readily notice, the temperature in the separation vessel 98 may vary depending on the content of the hydrocarbon-containing gas introduced into the system and the desired output product. In various embodiments, the separation vessel 98 may operate at a temperature lower than 5, 10 or 15 ° C and / or higher than -195, -185, -175 or -160 ° C. More specifically, the separation tank 98 may operate at a temperature ranging from 15 to -195 ° C, from 10 to -185 ° C, from 5 to -175 ° C, or from 5 to -160 ° C.

[0106] As shown in FIG. 2, the methane-enriched steam overhead stream in conduit 226 may be directed to a compressor 96 that compresses the stream. The compressed stream in line 228 is then reintroduced into the cooling passage 34 of the third cooling zone 32 for additional cooling and condensation, as described above with respect to FIG.

[0107] It should be noted that the first cooling system 12, the second cooling system 14, the first closed mixed loop (pipelines 238, 240, 242, 244, 246, 248, 250, 252, 254, 256, 258, 260, 262, 264 , 266 and 268) cooling and a second closed mixed circuit (pipelines 270, 272, 274, 276, 278, 280, 282, 284, 286, 288 and 290) cooling, depicted in Fig.2, which are not described above with respect to Fig. 2 operate in the same manner as previously described with respect to FIG. 1. The only difference is that the corresponding piping in FIG. 2 is indicated differently to take into account the specific embodiment of the system depicted in FIG. 2. In addition, the remaining stages involved in the liquefaction of a hydrocarbon-containing gas, not mentioned above with respect to FIG. 2 (pipelines 210, 212, 214, 216, 218, 230, 232, 234 and 236), function in the same (or similar) way as previously described with respect to FIG.

[0108] FIG. 3 illustrates an LNG extraction unit 10 that includes a turboexpander 94 connected in operation through a conduit 320 to a third cooling zone 32 of a first cooling system 12. As shown in FIG. 3, at least a portion of the hydrocarbon containing gas stream passing through the cooling passage 34 to the third cooling zone 32 can be routed through a pipe 320 to a turboexpander 94, where it can expand as a two-phase stream. Turbo expander 94 may operate under the same or similar conditions as previously described with respect to FIG. 2. Although not shown in FIG. 3, the vacuum drum may be in fluid communication between the turboexpander 94 and the third cooling zone 32 in certain embodiments.

[0109] The expanded two-phase stream in line 322 is then directed to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane depleted (line 324) and a vapor head fraction that is rich in methane (line 326). The separator 98 may be the same separation tank as previously described with respect to FIG. 2, and it may function under similar operating conditions. After separation, the vapor head fraction in conduit 326 is then reintroduced into the cooling passage 34 of the third cooling zone 32 for additional cooling and condensation, as described above with respect to FIG.

[0110] The methane-depleted bottom stream in conduit 324 may be in the form of a liquid, and it may contain most of the compounds having six or more carbon atoms initially in the stream in conduit 322. For example, the methane-depleted bottom stream in conduit 324 may contain at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 322.

[0111] The methane-enriched steam overhead stream in conduit 326 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 326 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched steam overhead in line 326 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in conduit 326 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent of the methane initially present in conduit 322.

[0112] Referring again to FIG. 3, here the turboexpander 94 is connected to the compressor 96 via the shaft 95. The compressor 96 may be at least partially driven by operation from the turboexpander 94. As shown in FIG. 3, the vaporized gaseous the first mixed refrigerant leaves the heating passage 36 for the refrigerant in the third cooling zone 32 through line 364, and then is introduced into the compressor 96, where it is compressed before being introduced into the compressor 48. After compression, the compressed stream in line 366 is introduced into the first stage 54 of the compressor and dopo It is carefully processed as discussed above with respect to FIG. 1. Although not shown in FIG. 3, a vacuum drum may be in fluid communication between compressor 96 and heating passage 36.

[0113] It should be noted that the first cooling system 12, the second cooling system 14, and the second closed mixed loop (pipelines 370, 372, 374, 376, 378, 380, 382, 384, 386, 388, and 390) of the cooling shown in FIG. .3, which are not described above with respect to FIG. 3, function in the same (or similar) manner as previously described with respect to FIG. 1. The only difference is that the corresponding pipelines in FIG. 3 are designated differently to take into account the specific embodiment of the system depicted in FIG. 3. In addition, the remaining steps involved in the liquefaction of hydrocarbon-containing gas, not mentioned above with respect to Figure 3 (pipelines 310, 312, 314, 316, 318, 328, 330, 332 and 334), and not taken into account the stages in the first closed mixed circuit (pipelines 336, 338, 340, 342, 344, 346, 348, 350, 352, 354, 356, 358, 360, 362 and 368) of cooling function in the same (or similar) manner as previously described with respect to FIG. 1.

[0114] FIG. 4 illustrates an LNG extraction unit 10 that includes a turboexpander 94 operably connected through a pipe 420 to a third cooling zone 32 of a first cooling system 12. As shown in FIG. 4, at least a portion of the hydrocarbon containing gas stream passing through the cooling passage 34 of the third cooling zone 32 can be routed through a pipe 420 to a turboexpander 94, where it can expand as a two-phase stream. Turbo expander 94 may operate under the same or similar conditions as previously described with respect to FIG. 2. Although not shown in FIG. 4, a vacuum drum may be in fluid communication between the turboexpander 94 and the third cooling zone 32 in certain embodiments.

[0115] The expanded two-phase stream in line 422 is then directed to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane depleted (line 424) and a vapor head fraction that is rich in methane (line 426). The separator 98 may be the same separation tank as previously described with respect to FIG. 2, and it may function under similar operating conditions. After separation, the vapor head fraction in line 426 is then reintroduced into the cooling passage 34 of the third cooling zone 32 for additional cooling and condensation, as described above with respect to FIG. 1.

[0116] The methane-depleted bottom stream in conduit 424 may be in the form of a liquid and may contain most of the compounds having six or more carbon atoms originally in the stream in conduit 422. For example, the methane-depleted bottom stream in conduit 324 may contain at least at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 422.

[0117] The methane-rich steam overhead stream in conduit 426 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 426 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched vapor overhead stream in conduit 426 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in line 426 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent of the methane originally present in the stream from line 422.

[0118] Referring again to FIG. 4, here the turboexpander 94 is connected to the compressor 96 via the shaft 95. The compressor 96 may be at least partially driven by operation from the turboexpander 94. As shown in FIG. 4, the vaporized gaseous the second mixed refrigerant leaves the heating passage 42 for the refrigerant in the cooling zone 38 through line 468 and is then introduced into the compressor 96, where it is compressed before being introduced into the compressor 72. After compression, the compressed stream in line 470 is introduced into the first stage of the compressor 74 and further processed as discussed above with respect to FIG. 1. Although not shown in FIG. 4, the vacuum drum may be in fluid communication between compressor 96 and heating passage 42.

[0119] It should be noted that the first cooling system 12, the second cooling system 14, and the first closed mixed loop (pipelines 436, 438, 440, 442, 444, 446, 448, 450, 452, 454, 456, 458, 460, 462 464 and 466) of the cooling depicted in FIG. 4, which are not described above with respect to FIG. 4, operate in the same (or similar) manner as previously described with respect to FIG. 1. The only difference is that the corresponding piping in FIG. 4 is indicated differently to take into account the specific embodiment of the system depicted in FIG. 4. In addition, the remaining stages involved in the liquefaction of a hydrocarbon-containing gas, not mentioned above with respect to Figure 4 (pipelines 410, 412, 414, 416, 418, 428, 430, 432 and 434), and not taken into account the stages in the second closed mixed circuit (piping 472, 474, 476, 478, 480, 482, 484, 486, 488, and 490) cooling function in the same (or similar) manner as previously described with respect to Figure 1

[0120] FIG. 5 illustrates an LNG extraction unit 10 that includes a turboexpander 94 operably connected through a conduit 522 to a cooling zone 38 of a second cooling system 14. As shown in FIG. 5, at least a portion of the hydrocarbon containing gas stream passing through the cooling passage 40 of the cooling zone 38 may be directed through a conduit 522 to a turboexpander 94, where it can expand as a two-phase stream. Turbo expander 94 may operate under the same or similar conditions as previously described with respect to FIG. 2. Although not shown in FIG. 5, the vacuum drum may be in fluid communication between the turboexpander 94 and the cooling zone 38 in certain embodiments.

[0121] The expanded two-phase stream in line 524 is then directed to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane depleted (line 526) and a vapor head fraction that is rich in methane (line 528). The separator 98 may be the same separation tank as previously described with respect to FIG. 2, and it may function under similar operating conditions.

[0122] The methane-depleted bottom stream in conduit 526 may be in the form of a liquid and may contain most compounds having six or more carbon atoms originally in the stream in conduit 524. For example, the methane-depleted bottom stream in conduit 526 may contain at least at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 524.

[0123] The methane-enriched steam overhead stream in conduit 528 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 528 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched vapor overhead stream in conduit 528 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in conduit 528 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent methane initially present in the conduit 524.

[0124] Referring again to FIG. 5, here the turboexpander 94 is connected to the compressor 96 via the shaft 95. The compressor 96 may be at least partially driven by operation obtained from the turboexpander 94. As shown in FIG. 5, methane enriched the vapor head stream in conduit 528 may be directed to a compressor 96, which compresses the stream. The compressed stream in line 530 is then re-introduced into the cooling passage 40 of the cooling zone 38 for additional condensation and subcooling, as described above with respect to FIG.

[0125] It should be noted that the first cooling system 12, the second cooling system 14, the first closed mixed circuit (pipelines 538, 540, 542, 544, 546, 548, 550, 552, 554, 556, 558, 560, 562, 564 566 and 568) cooling and a second closed mixed loop (pipelines 570, 572, 574, 576, 578, 580, 582, 584, 586, 588 and 590) cooling, shown in Fig.5, which are not described above with respect to Fig. 5 function in the same (or similar) manner as previously described with respect to FIG. 1. The only difference is that the corresponding pipelines in FIG. 5 are designated differently to take into account the specific embodiment of the system depicted in FIG. 5. In addition, the remaining stages involved in the liquefaction of a hydrocarbon-containing gas, not mentioned above with respect to FIG. 5 (pipelines 510, 512, 514, 516, 518, 520, 532, 534 and 536), function in the same (or similar) way as previously described with respect to FIG.

[0126] FIG. 6 illustrates an LNG extraction unit 10 that includes a turboexpander 94, operatively connected through a conduit 622 to a cooling zone 38 of a second cooling system 14. As shown in FIG. 6, at least a portion of the hydrocarbon containing gas stream passing through the cooling passage 40 of the cooling zone 38 may be directed through a conduit 622 to a turboexpander 94 where it can expand as a two-phase stream. Turbo expander 94 may operate under the same or similar conditions as previously described with respect to FIG. 2. Although not shown in FIG. 6, the vacuum drum may be in fluid communication between the turboexpander 94 and the cooling zone 38 in certain embodiments.

[0127] The expanded two-phase stream in line 624 is then sent to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane-depleted (line 626) and a steam head fraction that is rich in methane (line 628). The separator 98 may be the same separation tank as previously described with respect to FIG. 2, and it may function under similar operating conditions. After separation, at least a portion of the vapor head fraction in conduit 628 is then reintroduced into the cooling passage 40 of the cooling zone 38 for additional condensation and supercooling, as described above with respect to FIG.

[0128] The methane-depleted bottom stream in conduit 626 may be in the form of a liquid and may contain most of the compounds having six or more carbon atoms initially in the stream in conduit 624. For example, the methane-depleted bottom stream in conduit 626 may contain at least at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 624.

[0129] The methane-enriched steam overhead stream in conduit 628 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 628 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched vapor overhead stream in conduit 628 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in conduit 628 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent of the methane initially present in conduit 624.

[0130] Referring again to FIG. 6, here the turboexpander 94 is connected to the compressor 96 via the shaft 95. The compressor 96 may be at least partially driven by operation obtained from the turboexpander 94. As shown in FIG. 6, the vaporized gaseous the first mixed refrigerant leaves the heating passage 36 for the refrigerant in the third cooling zone 32 through line 664 and is then introduced into the compressor 96, where it is compressed before being introduced into the compressor 48. After compression, the compressed stream in line 666 is introduced into the first stage of the compressor 54 and add fully processed as discussed above with respect to FIG. 1. Although not shown in FIG. 6, a vacuum drum may be in fluid communication between compressor 96 and heating passage 36.

[0131] It should be noted that the first cooling system 12, the second cooling system 14 and the second closed mixed loop (pipelines 670, 672, 674, 676, 678, 680, 682, 684, 686, 688 and 690) of the cooling shown in FIG. .6, which are not described above with respect to FIG. 6, function in the same (or similar) manner as previously described with respect to FIG. 1. The only difference is that the corresponding piping in FIG. 6 is designated differently to take into account the specific embodiment of the system depicted in FIG. 6. In addition, the remaining stages involved in the liquefaction of a hydrocarbon-containing gas, not mentioned above with respect to FIG. 6 (pipelines 610, 612, 614, 616, 618, 620, 630, 632 and 634), and not taken into account the stages in the first closed mixed circuit (pipelines 636, 638, 640, 642, 644, 646, 648, 650, 652, 654, 656, 658, 660, 662 and 668) of cooling function in the same (or similar) manner as previously described with respect to FIG. one.

[0132] FIG. 7 illustrates an LNG extraction unit 10 that includes a turboexpander 94 operably connected through a conduit 722 to a cooling zone 38 of a second cooling system 14. As shown in FIG. 7, at least a portion of the hydrocarbon containing gas stream passing through the cooling passage 40 of the cooling zone 38 can be directed through a conduit 722 to a turboexpander 94, where it can expand as a two-phase stream. Turbo expander 94 may operate under the same or similar conditions as previously described with respect to FIG. 2. Although not shown in FIG. 7, a vacuum drum may be in fluid communication between the turboexpander 94 and the cooling zone 38 in certain embodiments.

[0133] The expanded two-phase stream in line 724 is then directed to a separator 98, which separates the expanded stream into a heavy liquid fraction that is methane-depleted (line 726), and a vapor head fraction that is rich in methane (line 728). The separator 98 may be the same separation tank as previously described with respect to FIG. 2, and it may function under similar operating conditions. After separation, at least a portion of the vapor head fraction in conduit 728 is then reintroduced into the cooling passage 40 of the cooling zone 38 for additional condensation and subcooling, as described above with respect to FIG.

[0134] The methane-depleted bottom stream in conduit 726 may be in the form of a liquid and may contain most of the compounds having six or more carbon atoms originally in the stream in conduit 724. For example, the methane-depleted bottom stream in conduit 626 may contain at least at least 70, 80, 90, 95, or 99 percent of compounds having six or more carbon atoms initially present in the stream from conduit 724.

[0135] The methane-enriched steam overhead stream in conduit 728 may contain most of the methane. For example, a methane-enriched steam overhead stream in conduit 728 may contain at least about 10, 25, 40, or 50 and / or no more than about 99.9, 99, 95, or 85 molar percent of methane. More specifically, the methane-enriched steam overhead stream in conduit 728 may contain in the range of about 10 to 99.9, 25 to 99, 40 to 95, or 50 to 85 molar percent of methane. In addition, the methane-enriched steam overhead stream in conduit 728 may contain at least 50, 60, 70, 80, 90, 95, 99, or 99.9 percent of the methane originally present in the conduit 724.

[0136] Referring again to FIG. 7, here the turboexpander 94 is connected to the compressor 96 via the shaft 95. The compressor 96 may be at least partially driven by operation from the turboexpander 94. As shown in FIG. 7, the vaporized gaseous the second mixed refrigerant leaves the heating passage 42 for the refrigerant in the cooling zone 38 through line 768 and is then introduced into the compressor 96, where it is compressed before being introduced into the compressor 72. After compression, the compressed stream in line 770 is introduced into the first stage of the compressor 74 and processed as discussed above with respect to FIG. 1. Although not shown in FIG. 7, a vacuum drum may be in fluid communication between compressor 96 and heating passage 42.

[0137] It should be noted that the first cooling system 12, the second cooling system 14, and the first closed mixed loop (pipelines 736, 738, 740, 742, 744, 746, 748, 750, 752, 754, 756, 758, 760, 762 764 and 766) of the cooling depicted in FIG. 7, which are not described above with respect to FIG. 7, operate in the same (or similar) manner as previously described with respect to FIG. 1. The only difference is that the corresponding piping in FIG. 7 is indicated differently to take into account the specific embodiment of the system depicted in FIG. 7. In addition, the remaining stages involved in the liquefaction of a hydrocarbon-containing gas, not mentioned above with respect to FIG. 7 (pipelines 710, 712, 714, 716, 718, 720, 730, 732 and 734), and not taken into account the stages in the second closed mixed circuit (pipelines 772, 774, 776, 778, 780, 782, 784, 786, 788 and 790) cooling function in the same (or similar) manner as previously described with respect to Figure 1.

Definitions

[0138] It should be understood that the following is not intended to constitute an exclusive list of defined terms. And other definitions may be given in the above description, such as, for example, definitions accompanying the use of a defined term in context.

[0139] As used herein, the terms defining the singular indicate one or more.

[0140] As used herein, the term “and / or” when used in a list of two or more objects means that any of the listed objects can be used on its own or any combination of two or more of the listed objects can be used. For example, if a composition is described as containing components A, B and / or C, the composition may contain A by itself; B on its own; C in itself; A and B in combination; A and C in combination, B and C in combination, or A, B, and C in combination.

[0141] As used herein, the terms "containing", "containing" and "containing" are open transitional terms used to transition from the subject mentioned before this term to one or more elements mentioned after this term, where the element or elements listed after transitional terms are not necessarily just the elements that make up the subject.

[0142] As used herein, the terms “having”, “has” and “have” have the same open meaning as “containing”, “containing” and “containing” above.

[0143] As used herein, the terms “including”, “including” and “included” have the same open meaning as “containing”, “containing” and “containing” above.

[0144] As used herein, the terms "first", "second", "third", and the like, are used to describe various elements, and such elements should not be limited to these terms. These terms are used only to distinguish one element from another, and they do not necessarily imply a specific order or even a specific element. For example, an element may be considered as the “first” element in the description and as the “second” element in the claims without deviating from the scope of the present invention. Consistency is maintained in the description and in each independent claim, but it is not necessarily assumed that such nomenclature is always consistent with each other.

Numerical ranges

[0145] The present description uses numerical ranges to quantify certain parameters related to the present invention. You must understand that when numerical ranges are given, such ranges should be considered as providing literal support for the limitations of the claims that mention only the lower values of the range, as well as the limitations of the claims that mention only the upper values of the range. For example, the described numerical range of 10 to 100 provides literal support for a claim claiming “greater than 10” (without upper bounds) and a claim claim mentioning “less than 100” (without lower bounds).

The claims are not limited to the described options for implementation

[0146] The preferred forms of the present invention described above should be used only as an illustration, and they should not be used in a limiting sense to interpret the scope of the present invention. Modifications of the illustrative embodiments given above can easily be carried out by a person skilled in the art without departing from the spirit of the present invention.

[0147] The authors hereby declare their intention to rely on the Doctrine of Equivalents to define and evaluate a reasonably limited scope of the present invention, as they relate to any device that is not materially deviating, but is outside the literal scope of the present invention, as set forth in the following claims .

Claims (62)

1. A method of liquefying a hydrocarbon-containing gas, the method includes: (a) introducing a fully condensed first mixed refrigerant, a compressed second mixed refrigerant, and a hydrocarbon-containing gas containing feed stream into the first cooling system; (b) expanding at least a portion of the fully condensed first mixed refrigerant to form an expanded first mixed refrigerant, wherein the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (c) cooling at least a portion of the feed stream and the compressed second mixed refrigerant in the first cooling system by indirect heat exchange with the expanded first mixed refrigerant to form a first cooled feed stream and a fully condensed second mixed refrigerant; (d) expanding at least a portion of the fully condensed second mixed refrigerant to form an expanded second mixed refrigerant, wherein the fully condensed second mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (e) cooling at least a portion of the first chilled feed stream in a second cooling system by indirect heat exchange with the expanded second mixed refrigerant to form a second chilled feed stream; (f) expanding at least a portion of a first cooled feed stream or a second cooled feed stream in a turboexpander to form an expanded feed stream; (g) separating at least a portion of the expanded feed stream in the separator to form a vapor head fraction and a liquid bottom fraction; (h) compressing at least a portion of the vapor head fraction in the compressor by at least partially driven by a turbo expander to form a compressed vapor fraction; and (i) if the expansion in step (f) includes the expansion of at least a portion of the first chilled feed stream, then at least a portion of the compressed vapor fraction in the first cooling system is cooled, or if the expansion in step (f) includes the expansion of at least a portion of the second chilled the feed stream, then at least a portion of the compressed vapor fraction in the second cooling system is cooled. 2. The method according to claim 1, further comprising supercooling at least a portion of the fully condensed first mixed refrigerant in step (c) to form a supercooled first mixed refrigerant, wherein the completely condensed first mixed refrigerant in step (b) contains a supercooled first mixed refrigerant. 3. The method according to claim 1, further comprising supercooling at least a portion of the fully condensed second mixed refrigerant in step (e) to form a supercooled second mixed refrigerant, wherein the completely condensed second mixed refrigerant in step (d) contains supercooled second mixed refrigerant. 4. The method according to claim 1, in which the first mixed refrigerant contains at least two compounds selected from the group consisting of hydrocarbons containing from 2 to 4 carbon atoms. 5. The method according to claim 1, in which the second mixed refrigerant contains at least two compounds selected from the group consisting of nitrogen and hydrocarbons containing from 1 to 3 carbon atoms. 6. The method according to claim 1, wherein the first cooled feed stream expands during expansion in step (f). 7. The method according to claim 1, wherein the second cooled feed stream expands during expansion in step (f). 8. A method of liquefying a hydrocarbon-containing gas, comprising: (a) introducing a fully condensed first mixed refrigerant, a compressed second mixed refrigerant, and a hydrocarbon-containing gas containing feed stream into the first cooling system; (b) expanding at least a portion of the fully condensed first mixed refrigerant to form an expanded first mixed refrigerant; (c) cooling at least a portion of the feed stream and the compressed second mixed refrigerant in the first cooling system by indirect heat exchange with the expanded first mixed refrigerant to form a cooled feed stream and a fully condensed second mixed refrigerant; (d) expanding at least a portion of the fully condensed second mixed refrigerant to form an expanded second mixed refrigerant; (e) cooling at least a portion of the cooled feed stream in the second cooling system by indirect heat exchange with the expanded second mixed refrigerant to form a second cooled feed stream; f) expanding at least a portion of the second cooled feed stream in a turboexpander to form an expanded feed stream; (g) separating at least a portion of the expanded feed stream in the separator to form a vapor head fraction and a liquid bottom fraction; (h) compressing at least a portion of the vapor head fraction in the compressor at least partially driven by a turboexpander to form a compressed vapor fraction; and (i) cooling at least a portion of the compressed vapor fraction in a second cooling system. 9. The method of claim 8, further comprising supercooling at least a portion of the fully condensed first mixed refrigerant in step (c) to form a supercooled first mixed refrigerant, wherein the fully condensed first mixed refrigerant in step (b) contains a supercooled first mixed refrigerant. 10. The method of claim 8, further comprising supercooling at least a portion of the fully condensed second mixed refrigerant in step (e) to form a supercooled second mixed refrigerant, wherein the fully condensed second mixed refrigerant in step (d) contains supercooled second mixed refrigerant. 11. A system for liquefying a hydrocarbon-containing gas, the system comprises: (a) a first cooling system comprising a first cooling zone disposed therein, wherein the first cooling zone is configured to cool a feed stream containing a hydrocarbon-containing gas by indirect heat exchange with a first mixed refrigerant to form a first cooled feed stream; (b) a first closed mixed cooling circuit at least partially located in the first cooling system, wherein the first closed mixed cooling circuit comprises a first mixed refrigerant; (c) a second cooling system in fluid communication with the first cooling system, the second cooling system comprising a second cooling zone disposed therein, the second cooling zone being configured to cool the first cooled feed stream by indirect heat exchange with the second mixed refrigerant to form a second cooled feed stream; (d) a second closed mixed cooling circuit at least partially located in the second cooling system, wherein the second closed mixed cooling circuit comprises a second mixed refrigerant; (e) a turbo-expander in fluid communication with a first cooling system or a second cooling system, wherein the turbo-expander is configured to expand a first cooled feed stream or a second cooled feed stream to form an expanded stream; (f) a separator in fluid communication with a turboexpander, the separator being configured to separate the expanded stream into a vapor head fraction and a liquid bottom fraction; (g) a compressor at least partially driven by operation obtained from a turboexpander, the compressor being configured to at least partially compress the vapor head fraction to form a compressed vapor fraction; and (h) a conduit for returning at least a portion of the compressed vapor fraction to the first cooling system or to the second cooling system. 12. The system of claim 11, wherein the turboexpander is in fluid communication with the first cooling system and the pipeline returns at least a portion of the vapor head fraction to the first cooling system. 13. The system of claim 11, wherein the turboexpander is in fluid communication with the second cooling system and the pipeline returns at least a portion of the vapor head fraction to the second cooling system. 14. The system of claim 11, wherein the second cooling zone is configured to supercool the second mixed refrigerant. 15. A method of liquefying a hydrocarbon-containing gas, the method includes: (a) introducing a fully condensed first mixed refrigerant, a compressed second mixed refrigerant, and a hydrocarbon-containing gas containing feed stream into the first cooling system; (b) expanding at least a portion of the fully condensed first mixed refrigerant to form an expanded first mixed refrigerant, wherein the fully condensed first mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (c) cooling at least a portion of the feed stream and the compressed second mixed refrigerant in the first cooling system by indirect heat exchange with the expanded first mixed refrigerant to form a first cooled feed stream and a fully condensed second mixed refrigerant; (d) expanding at least a portion of the fully condensed second mixed refrigerant to form an expanded second mixed refrigerant, wherein the fully condensed second mixed refrigerant is not subjected to phase separation prior to or after the expansion step; (e) cooling at least a portion of the first chilled feed stream in a second cooling system by indirect heat exchange with the expanded second mixed refrigerant to form a second chilled feed stream; (f) expanding at least a portion of the first cooled feed stream to form an expanded feed stream; (g) separating at least a portion of the expanded feed stream in the separator to form a vapor head fraction and a liquid bottom fraction; (h) cooling at least a portion of the vapor head fraction in the first cooling system; (i) activating the compressor with a turboexpander. 16. A system for liquefying a hydrocarbon-containing gas, the system comprises: (a) a first cooling system comprising a first cooling zone disposed therein, wherein the first cooling zone is configured to cool a feed stream containing a hydrocarbon-containing gas by indirect heat exchange with a first mixed refrigerant to form a first cooled feed stream; (b) a first closed mixed cooling circuit at least partially located in the first cooling system, wherein the first closed mixed cooling circuit contains a first mixed refrigerant, wherein the first closed mixed cooling circuit does not contain a phase separator; (c) a second cooling system in fluid communication with the first cooling system, the second cooling system comprising a second cooling zone disposed therein, the second cooling zone being configured to cool the first cooled feed stream by indirect heat exchange with the second mixed refrigerant to form a second cooled feed stream; (d) a second closed mixed cooling circuit at least partially located in the second cooling system, wherein the second closed mixed cooling circuit contains a second mixed refrigerant, wherein the second closed mixed cooling circuit does not contain a phase separator; (e) a turbo-expander in fluid communication with the first cooling system, wherein the turbo-expander is configured to expand a first cooled feed stream or a second cooled feed stream to form an expanded stream; (f) a separator in fluid communication with a turboexpander, the separator being configured to separate the expanded stream into a vapor head fraction and a liquid bottom fraction; (g) a pipeline for returning at least a portion of the vapor head fraction to the first cooling system; and (h) a compressor at least partially driven by operation obtained from a turboexpander, the compressor being configured to at least partially compress the first mixed refrigerant, second mixed refrigerant, or vapor head fraction. 17. The method according to claim 1, in which the separator operates at a pressure of at least 3.5 MPa. 18. The method of claim 8, in which the separator operates at a pressure of at least 3.5 MPa. 19. The system of claim 11, wherein the separator is configured to operate at a pressure of at least 3.5 MPa.

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