JP2009544923A - Method and apparatus for liquefying hydrocarbon streams - Google Patents

Abstract

  A method for liquefying a hydrocarbon stream, such as natural gas, from a feed stream (10), wherein (a) circulating a first refrigerant stream (70) in a first refrigerant circuit (110); (b) Cooling the first refrigerant stream (70) in one or more heat exchangers (14) of the first cooling stage (100) to obtain a cooled first refrigerant stream (20); (c) ) Passing at least a portion of the cooled first refrigerant stream (20) through one or more expanders to obtain one or more expanded and cooled first refrigerant streams (30); The expanded and cooled first refrigerant stream (30) or at least one thereof and the feed stream (10) are passed through the one or more heat exchangers (14), and the cooled hydrocarbon stream (40) is passed through. Obtaining (e) the cooled hydrocarbon stream (40) relative to the second refrigerant stream (50); Passing through a second cooling stage (200) to obtain a liquefied hydrocarbon stream (60), wherein at least one of the expanders is an expansion turbine (12) and is made in step (c) The above method, wherein the work energy of the expansion turbine (12) is used in the first refrigerant circuit (110).

Description

  The present invention relates to a method and apparatus for liquefying a hydrocarbon stream, but not limited to natural gas.

  Several methods are known for liquefying a natural gas stream to obtain liquefied natural gas (LNG). It is desirable to liquefy the natural gas stream for several reasons. As an example, when natural gas is stored or transported over a long distance, it is easier to use liquid than gas. This is because the liquid occupies a smaller volume and does not need to be stored at high pressure.

  US 6,105,389A shows a method and apparatus for liquefying natural gas using a compressed coolant mixture, after the compressed coolant mixture is subcooled, expanded and vaporized, Natural gas is liquefied in the second cooling stage. In the first cooling stage, a portion of the first coolant mixture is expanded by an expansion valve to cool the coolant mixture. The problem with expansion valves, however, is that because they are isenthalpy, the work available from the expansion of fluids such as coolant is essentially lost when the pressure in such valves drops.

  The object of the present invention is to increase the efficiency of the liquefaction method and liquefaction apparatus.

One or more of the above or other purposes,
A method for liquefying a hydrocarbon stream, such as natural gas, from a feed stream,
(A) circulating the first refrigerant flow in the first refrigerant circuit;
(B) cooling the first refrigerant stream in one or more heat exchangers of the first cooling stage to obtain a cooled first refrigerant stream;
(C) passing at least a portion of the cooled first refrigerant stream through one or more expanders to obtain one or more expanded and cooled first refrigerant streams;
(D) passing the expanded and cooled first refrigerant stream or at least one thereof and the feed stream through the one or more heat exchangers to obtain a cooled hydrocarbon stream;
(E) passing the cooled hydrocarbon stream through a second cooling stage relative to the second refrigerant stream to obtain a liquefied hydrocarbon stream;
Achieved by the present invention which provides the above method, wherein at least one of the expanders is an expansion turbine and the work energy of the expansion turbine produced in step (c) is used in the first refrigerant circuit it can.

  An advantage of the present invention is that at least a portion of the first refrigerant stream is expanded by one or more expansion turbines to reduce the pressure of the first refrigerant before being used to cool the feed stream in the heat exchanger. By lowering, the expansion of the first refrigerant becomes substantially isentropic, so that the efficiency of the first cooling is increased. By expanding the gas at approximately isentropy to a lower pressure, the internal energy is reduced from the expanding gas, creating at least a portion of this energy as useful work. This work energy is then used to help drive another unit or device or part thereof, such as a compressor, pump or generator, somewhere in the liquefaction method, liquefaction process and / or liquefaction device. Can be used effectively.

  The hydrocarbon stream may be any suitable gas stream to be liquefied, but is usually a natural gas stream obtained from a natural gas or petroleum reservoir. Alternatively, the natural gas stream can be obtained from another source, including a synthetic source such as a Fischer-Tropsch process.

  Usually, the natural gas stream consists essentially of methane. Preferably the feed stream comprises at least 60 mol% methane, more preferably at least 80 mol% methane.

Depending on the source, natural gas may contain not only aromatic hydrocarbons but also hydrocarbons heavier than methane such as ethane, propane, butane and pentane. Natural gas streams may also contain non-hydrocarbons such as H ₂ O, N ₂ , CO ₂ , H ₂ S, other sulfur compounds, and the like.

If necessary, the feed stream containing natural gas may be pretreated before use. This pretreatment can include reduction and / or removal of unwanted components such as CO ₂ and H ₂ S, or other steps such as initial cooling, pre-pressurization. These steps are well known to those skilled in the art and will not be further described here.

  As used herein, the term “feed stream” refers to any hydrocarbon-containing composition that typically contains large amounts of methane. In addition to methane, natural gas contains various amounts of ethane, propane and heavy hydrocarbons. Its composition varies depending on the type and location of the gas. In general, hydrocarbons heavier than methane must be removed from natural gas for several reasons, such as having different freezing or liquefaction temperatures that may clog parts of the methane liquefaction plant. C2-4 hydrocarbons can be used as a source of natural gas liquid.

Thus, the term “feedstock stream” also includes, but is not limited to, compositions prior to treatment, including cleaning, dehydration and / or scrubbing, including but not limited to sulfur, sulfur compounds, carbon dioxide, water, And compositions that have been partially, substantially, or completely processed for the reduction and / or removal of one or more compounds or substances, including C ₂ ⁺ hydrocarbons.

  The term “inflator” includes any unit, device or apparatus that can reduce the pressure in a flow. The expander includes not only an expansion turbine but also a valve, and also includes a one-phase expander or a two-phase expander. If at least one expander of the heat exchanger in the first cooling stage is an expansion turbine, one or more other expanders may be valves. Preferably, everything in the heat exchanger of the first cooling stage is an expansion turbine.

  The first cooling stage of the present invention is aimed at lowering the temperature of the cooled hydrocarbon stream to below 0 ° C, usually in the range of -20 ° C to -70 ° C. Such a cooling stage is often referred to as a “pre-cooling” stage.

  Preferably the second cooling stage is separate from the first cooling stage. That is, the second cooling stage comprises one or more separate heat exchangers that use a second refrigerant circulating in the second refrigerant circuit, but the refrigerant in the second refrigerant stream is the first cooling stage. It is also possible to pass through at least one heat exchanger, preferably all the heat exchangers of the first cooling stage.

  Preferably, the first refrigerant circuit comprises one or more ambient cooling devices in front of the first heat exchanger.

  In one embodiment of the invention, the created work energy is used to raise the pressure of the first refrigerant stream before the first heat exchanger. One example of this is using work energy to drive one or more pumps that circulate the first refrigerant stream.

  Using work energy from one or more expansion turbines in the first cooling stage (configured to reduce the temperature of the hydrocarbon stream below 0 ° C.) allows the temperature of the associated refrigerant stream to expand before expansion. It is particularly advantageous when it is not intended to be a fairly low temperature such as -50 ° C or -100 ° C. In this way, the temperature rise of the refrigerant flow caused by the passage of one or more pumps (where the temperature rises as the pressure rises) is, for example, one or more such as water cooling and / or air cooling devices known in the art It can be extracted more easily by using an ambient cooling device. It is clearly insufficient to use an ambient cooling device alone to reduce the temperature of the refrigerant stream with the purpose of reducing the hydrocarbon stream to a sufficiently low temperature (e.g. below -100 <0> C).

  Thus, the present invention eliminates the need for additional cooling in the first refrigerant circuit that already requires one or more ambient cooling devices before the heat exchanger, so that the work energy provided by each expansion turbine is the first cooling or This is particularly advantageous when used in a precooling stage. In this way, the use of the work energy or exergy created is maximized or energy waste is at least minimized throughout the liquefaction process.

  In another embodiment of the invention, the first cooling stage comprises two or three heat exchangers, preferably each heat exchanger has an associated expansion turbine through which the first At least a portion of the cooled refrigerant stream is sent to provide an expanded and cooled first refrigerant stream to each heat exchanger.

In another aspect, the invention is an apparatus for liquefying a hydrocarbon stream, such as a natural gas stream, from a feed stream comprising:
Comprising at least a first refrigerant circuit, a first cooling stage, one or more expanders, and a second cooling stage;
Said first refrigerant circuit circulates a first refrigerant stream;
The first cooling stage has one or more heat exchangers for receiving the first refrigerant stream and obtaining a cooled first refrigerant stream;
The one or more expanders expand at least a portion of the cooled first refrigerant stream to provide one or more expanded first refrigerant streams, wherein the at least one expander is an expansion turbine; The work energy of the expansion turbine produced by expansion is used in the first refrigerant circuit;
The heat exchanger or each has a first inlet for taking up the feed stream and a second inlet for taking up the expanded first refrigerant stream or at least one of them; Providing a cooled hydrocarbon stream by cooling the feed stream;
The provided second cooling stage comprises one or more heat exchangers configured to receive the cooled hydrocarbon stream from the first cooling stage and to provide a liquefied hydrocarbon stream;
There is provided an apparatus as described above.
The embodiments of the present invention will now be described with reference to the accompanying drawings by way of example only and not limitation.
For purposes of explanation, one reference number is assigned to one conduit and the flow carried in that conduit. The same reference numbers indicate similar components.

1 is a schematic diagram of a liquefaction method according to an embodiment of the present invention.

  FIG. 1 shows an overall configuration for liquefying a hydrocarbon stream such as natural gas. An initial feed stream 10 containing natural gas is shown and this feed stream is pretreated to produce at least some heavy hydrocarbons and carbon dioxide, including but not limited to acid gases. You may isolate | separate impurities, such as carbon, nitrogen, helium, water, sulfur, and a sulfur compound.

  The feed stream 10 passes through a first cooling stage 100 that uses the first refrigerant circulating in the first cooling refrigerant circuit 110 to obtain a cooled hydrocarbon stream 40b. The first refrigerant may be any suitable component or preferably a mixture thereof including one or more, preferably two or more of nitrogen, methane, ethane, ethylene, propane, propylene, butane, pentane and the like.

  The feedstock stream 10 enters the first heat exchanger 14a from the inlet 32a and passes through the first heat exchanger 14a by a conduit 73a. On the other hand, the first refrigerant enters the first heat exchanger 14a from the inlet 36a and exits the first heat exchanger 14a through the pipe line 71a. In this way, the first refrigerant pipe 71a is also cooled in the first heat exchanger 14a.

  It is the cooled first refrigerant stream 20a that flows out of the first heat exchanger 14a at the outlet 38a. First and second fractions or portions 21a, 21b are made by a suitable divider (not shown), such as a dividing pipe, each consisting of a cooled first refrigerant stream 20a. The first portion 21a is sent to the first expansion turbine 12a. The first expansion turbine 12a expands the cooled first refrigerant fraction almost isentropically to provide an expanded and cooled first refrigerant stream 30a. The expanded stream 30a has an internal energy that is lower than the internal energy of stream 21a.

  This energy difference can be used as work, for example, to drive a unit or device in the first refrigerant circuit 110. In the configuration shown in FIG. 1, the energy provided by the first expansion turbine 12 a is used to drive a first pump 28 a that is part of the first cooling circuit 110. The function of the first pump 28a will be described later.

  In FIG. 1, the ratio of the first portion 21a and the second portion 21b of the cooled first refrigerant stream 20a can be any suitable ratio known in the art. When the first cooling stage 100 has two heat exchangers 14a and 14b and uses a mixed refrigerant, the ratio of the two pressure levels is, for example, 35/65. Examples of possible pressure levels in the heat exchangers 14a, 14b are 8 bar for the high pressure heat exchanger and 3 bar for the low pressure heat exchanger.

  The expanded stream 30a is returned back to the first heat exchanger 14a at or near the top of the first heat exchanger 14a, and the expanded stream 30a is directed downwardly as is known in the art. When vaporizing through, these lines are cooled in the first heat exchanger 14a carrying the feed stream 10 (line 73a) and the first refrigerant (line 71a). This provides a cooled hydrocarbon stream 40a.

  On the other hand, the vaporized first refrigerant is collected and the first steam from the first heat exchanger 14a via the outlet 42a at or near the bottom end of the first heat exchanger 14a. It can be discharged as outlet stream 90 a and sent to the first compressor 22 for recompression and circulation in the first refrigerant circuit 110.

  Next, the second fraction or portion 21b of the first cooled first refrigerant stream 20a and the cooled hydrocarbon stream 40a are the bottom end or bottom end of the second heat exchanger 14b. Nearly enters the second heat exchanger 14b via the inlets 36b and 32b respectively and passes upward. The first refrigerant stream passes through the second heat exchanger 14b via the outlet 38b at or near the top of the second heat exchanger 14b as a further cooled first refrigerant stream 20b, and the second Is expanded by the second expansion turbine 12b to provide a second expanded first refrigerant stream 30b, which is then fed back to the second heat exchanger 14b via the inlet 44b. 14b can be passed downward. When the second expanded stream 30b passes downward through the second heat exchanger 14b, the hydrocarbon stream (pipe 73b) passing upward through the second heat exchanger 14b in a manner known in the art. And the pipe line of the first refrigerant (pipe line 71b) is cooled. The second expanded refrigerant stream 30b is vaporized while passing downward through the second heat exchanger 14b and can be collected from the outlet 42b as a second vapor outlet stream 90b. The second steam outlet stream 90 b is sent to the first compressor 22 for recompression and circulation in the first cooling circuit 110.

  The second expanded stream 30b is expanded approximately isentropically by the second expansion turbine 12b and the energy difference between the previously expanded stream 20b and the later expanded stream 30b is determined in the first cooling circuit 110. It can also be used as work.

  As shown in FIG. 1, the first refrigerant collected from the first and second heat exchangers 14 a and 14 b is compressed by the compressor 22 to obtain a compressed flow 95, which is a water cooling and / or air cooling device. 26 to obtain a recondensed stream 70 for re-entering the heat exchangers 14a, 14b. In order to assist in the circulation of the recondensed first refrigerant stream 70, it is continuously pumped by the first and second pumps 28b, 28a and pumped stream 70a before the final ambient cooling device 29. obtain. The final ambient chiller 29 comprises one or more ambient chillers, such as water and / or air chillers, and a cooled pump delivery stream 70b that is ready for reuse in the heat exchangers 14a, 14b. Can be obtained.

  The pump is common in the refrigerant circuit but needs to be driven, i.e. it must input energy. The pump also raises the temperature of the flow when the flow through the pump is pressurized. In the present invention, it is particularly advantageous to drive or work the pumps 28a, 28b by using work energy created by the nearby or adjacent expansion turbines 12a, 12b. The work energy of the expansion turbines 12a, 12b can be delivered to the associated pumps 28a, 28b by any mechanical linkage (such as a common shaft) that interconnects them.

  For liquefaction plants in hot or warm climates, the temperature of the recondensed stream 70 is generally between 40 ° C. and 60 ° C., for example 50 ° C. Each pump in the first refrigerant circuit can raise the temperature of the recondensed flow by a few degrees Celsius, so that for the configuration shown in FIG. The standard temperature of 70a can be, for example, 53 ° C. to 56 ° C. Thus, one or more ambient cooling devices, such as ambient cooling device 29 shown in FIG. 1, can reduce the temperature of pumping stream 70a by 10-20 ° C., resulting in a standard for cooled pumping stream 70b. The typical temperature is 40 ° C. In cold or colder climates, the temperature of these streams may be 10-20 ° C lower, but the pumping effect is the same.

  One or both of the pumps 28a, 28b can be driven partially, substantially, or completely by the work energy from the expansion turbines 12a, 12b. In this way, the need for external energy in the first refrigerant circuit 110 is reduced, which makes it more efficient.

  If there are more serial heat exchangers in the first cooling stage 100, the further cooled first refrigerant stream 20b is split, passed through a further line of the first refrigerant, and the flow Continue for another heat exchanger until the last heat exchanger circulates all the first refrigerant as shown in FIG. 1 for 20b.

  The hydrocarbon stream exits second heat exchanger 14b via outlet 34b as cooled hydrocarbon stream 40b.

  Since each expansion turbine 12a, 12b can make the expansion of the first refrigerant substantially isentropic, the efficiency of the first cooling circuit 110 is increased. That is, the internal energy of the streams 30a, 30b is reduced, which benefits the efficiency of the process. Also, the lower internal energy of the circulating first refrigerant stream, e.g. lower entropy, is the same as the refrigerant temperature of the cooling device, thus improving the cooling that the circulating refrigerant stream performs in the heat exchanger, and The work given to the refrigerant compressor to recompress the refrigerant is / are reduced.

  Preferably, the first cooling stage 100 generally provides a feed stream 10 of less than 0 ° C., such as from −20 ° C. to −70 ° C., preferably from −20 ° C., depending on the type of process of the first cooling stage. Cool to -35 ° C or -40 ° C to -70 ° C.

  In one embodiment of the present invention, each heat exchanger in the multi-stage first cooling stage 100 provides a different first refrigerant pressure. The expanded refrigerant from each pressure stage can be compressed with one or more compressors, for example using different compressors for different refrigerant inlet pressures.

  In another embodiment of the invention, the feed stream does not pass through all the heat exchangers of the first cooling stage, but can pass through only one or more of the heat exchangers. For example, in the configuration shown in FIG. 1, the feed stream 10 can pass only through the second heat exchanger 14b to achieve the required cooling in the first cooling stage 100.

  Next, the final cooled hydrocarbon stream 40b from the second heat exchanger 14b uses a second refrigerant, preferably a mixed refrigerant, that circulates in a second refrigerant circuit 80 to be described later. The cooling stage 200 is sent.

  Various configurations are possible for the cooled hydrocarbon stream 40b passing through the second cooling stage 200 and the second refrigerant circuit 80. These configurations are well known in the art. These can optionally include one or more cooling stages in one vessel, such as optionally a cryogenic heat exchanger, at various pressure levels.

  The second cooling stage 200 can reduce the temperature of the cooled hydrocarbon stream 40b to obtain a liquefied hydrocarbon stream 60 having a temperature of about -130 ° C or less than -130 ° C.

  In the simple form shown in FIG. 1, the second refrigerant circuit 80 is configured to cause the vaporized second refrigerant outlet stream 50 a to be cooled with water and / or two second compressors 52 driven by a drive device 54. It passes through the air cooling device 56. After the cooling device 56, the second refrigerant for condensation passes through the heat exchangers 14 a, 14 b of the first cooling stage 100 through the pipe lines 75 a, 75 b and is liquefied for use in the second cooling stage 200. A second refrigerant stream 50 can be obtained.

  Accordingly, the second refrigerant is at least partially cooled by the first cooling stage 100. This configuration requires another heat exchanger to sufficiently cool the second refrigerant in order to use a portion of the cooling duty of the first cooling stage of the feed stream in the second cooling stage 200. In combination with the equivalent part of cooling the second refrigerant using the same device instead of the second cooling circuit 200, the method for liquefying the hydrocarbon feedstock stream such as natural gas is simplified. This therefore reduces the level of equipment and equipment required and lowers the main running costs of the method shown in FIG.

  Additional cooling of the feed stream, the cooled and / or liquefied hydrocarbon stream and / or the refrigerant may be performed in the first and second cooling stages (this is optionally a method for liquefying the hydrocarbon stream described herein). And / or coupled with another part of the device), it may be provided by one or more other refrigerants or refrigerant cycles.

  For example, the liquefied stream 60 can then preferably be subcooled in a third cooling stage (not shown). Supercooling can be accomplished by passing the liquefied stream through one or more stages using one or more supercooling heat exchangers. Preferably, each heat exchanger in the supercooling is cooled by a mixed (third) refrigerant. Additional cooling of the liquefied stream and / or supercooled refrigerant may be performed by one or more other refrigerants or refrigerant circuits (optionally another method and / or apparatus for liquefying a hydrocarbon stream described herein). Connected to the part).

  One skilled in the art will also readily appreciate that the liquefied natural gas can be further processed if necessary after liquefaction. As an example, the resulting LNG may be depressurized by a Joule-Thomson valve or a cold turboexpander.

Table 1 below gives an overview of the power requirements in the three cases.

  The specific output of the liquefaction process is defined as the refrigerant compressor power (in KW) required by the process divided by the amount of liquefied hydrocarbon stream (eg, LNG) obtained (in tpd).

  Case 1 drives the compressor of the cooling circuit for the first stage or precooling stage of a liquid natural gas liquefaction system that requires two heat exchangers and uses an expansion valve as described in US 6,105,389A It is related to the power required.

  Case 2 is electric power required to drive the compressor 22 in the liquefaction method shown in FIG. 1 (however, pumps 28a and 28b are not provided) as described above.

  Case 3 is electric power required to drive the compressor 22 of FIG. 1 when the first refrigerant circuit 110 includes the illustrated pumps 28a and 28b.

  As can be seen from the above, the power required for case 2 is smaller than the power required for case 1, so that the power required to recompress the first refrigerant in the first refrigerant circuit 110 is reduced by using the expansion turbine. It was done. Since the expanded first refrigerant (after passing through the expansion turbine) has lower energy, the required compression pressure is smaller and therefore colder than when using an expansion valve.

  Case 3 introduces pumps 28a and 28b driven by the work output of expansion turbines 12a and 12b. In the case 3, the efficiency of the first refrigerant circuit 110 is further increased by using the pumps 28a and 28b, so that the compressor is maintained in order to maintain the circulation of the first refrigerant in the first refrigerant circuit 110. Since the general propulsion power produced by 22 is reduced, it shows that the required power of the compressor 22 is smaller than the required power of the case 2.

  Those skilled in the art will appreciate that the present invention can be implemented in many ways without departing from the scope of the claims.

US 6,105,389A

10 Feedstock streams 12a, 12b Expansion turbines 14a, 14b Heat exchanger 22 Compressor 26 Cooling devices 28a, 28b Pump 29 Cooling device 52 Second compressor 54 Drive device 56 Cooling device 80 Second refrigerant circuit 100 First Cooling stage 110 First refrigerant circuit 200 Second cooling stage

Claims (15)

A method for liquefying a hydrocarbon stream, such as natural gas, from a feed stream (10) comprising:
(A) circulating the first refrigerant stream (70) in the first refrigerant circuit (110);
(B) cooling the first refrigerant stream (70) in one or more heat exchangers (14) of the first cooling stage (100) to obtain a cooled first refrigerant stream (20); ;
(C) passing at least a portion of the cooled first refrigerant stream (20) through one or more expanders to obtain one or more expanded and cooled first refrigerant streams (30);
(D) the expanded and cooled first refrigerant stream (30) or at least one thereof and the feedstock stream (10) through the one or more heat exchangers (14) and cooled hydrocarbon stream; Obtaining (40);
(E) passing the cooled hydrocarbon stream (40) through a second cooling stage (200) with respect to the second refrigerant stream (50) to obtain a liquefied hydrocarbon stream (60);
Wherein at least one of the expanders is an expansion turbine (12) and the work energy of the expansion turbine (12) produced in step (c) is used in the first refrigerant circuit (110). The above method.   The temperature of the cooled hydrocarbon stream (40) after the first cooling stage (100) is in the range of −20 ° C. to −70 ° C., and the second cooling stage (200) is the first cooling stage (200). The method of claim 1, wherein the method is separate from the cooling stage (100).   The method according to claim 1 or 2, wherein the first refrigerant circuit (110) comprises one or more ambient cooling devices (29) in front of the first heat exchanger (14).   4. The method according to claim 1, wherein the produced work energy is used to increase the pressure of the first refrigerant stream (70) before the first heat exchanger (14). The method described.   The method of claim 4, wherein the work energy is used to drive one or more pumps (28 a, 28 b) that circulate the first refrigerant stream (70).   The method according to any one of the preceding claims, wherein each expander in step (c) is an expansion turbine (12).   The method according to any one of the preceding claims, wherein the first cooling stage (100) comprises two or three heat exchangers (14a, 14b).   Each heat exchanger (14a, 14b) has an associated expansion turbine (12a, 12b), and at least a portion of the first cooled refrigerant stream (20a, 20b) is associated with the associated expansion turbine (12a, 12b). The method according to claim 7, wherein through 12b) an expanded and cooled first refrigerant stream (30a, 30b) is provided to the respective heat exchanger (14a, 14b).   The method according to claim 7 or 8, wherein each heat exchanger (14a, 14b) of the first cooling stage (100) provides a different first refrigerant pressure to step (c).   The refrigerant of the first refrigerant stream (70) is a mixed refrigerant consisting of a mixture of gases, and the gas is preferably selected from the group consisting of nitrogen, methane, ethane, ethylene, propane, propylene, butane and pentane. The method according to any one of claims 1 to 9.   The refrigerant of the second refrigerant stream (50) passes through at least one heat exchanger (14) of the first cooling stage (100), preferably all the heat of the first cooling stage (100). 11. A method according to any one of the preceding claims, passing through an exchanger (14). An apparatus for liquefying a hydrocarbon stream, such as a natural gas stream, from a feed stream (10),
Comprising at least a first refrigerant circuit (110), a first cooling stage (100), one or more expanders and a second cooling stage (200);
Said first refrigerant circuit (110) circulates a first refrigerant stream (70);
The first cooling stage (100) has one or more heat exchangers (14) to receive the first refrigerant stream (70) and to obtain a cooled first refrigerant stream (20). ;
The one or more expanders expand at least a portion of the cooled first refrigerant stream (20) to provide one or more expanded first refrigerant streams (30), wherein at least one of the expanders Is the expansion turbine (12), and the work energy of the expansion turbine (12) produced by expansion is used in the first refrigerant circuit (110);
The heat exchanger (14) or each of which takes a first inlet for taking in the feed stream (10) and the expanded first refrigerant stream (30) or at least one of them; Providing a cooled hydrocarbon stream (40) by cooling the feed stream (10);
The provided second cooling stage (200) is configured to receive the cooled hydrocarbon stream (40) from the first cooling stage (100) and provide a liquefied hydrocarbon stream (60). One or more heat exchangers provided;
Said device.   13. Apparatus according to claim 12, wherein the first cooling stage (100) comprises two or three heat exchangers (14a, 14b), each having an associated expansion turbine (12a, 12b).   The first refrigerant circuit (110) includes one or more pumps (28a, 28b) for circulating the first refrigerant flow (70), and the work energy generated by the expansion is the pump (28a, 14. An apparatus according to claim 12 or claim 13 used to drive one or more of 28b).   The first cooling stage (100) provides a cooled first refrigerant stream (20) having a temperature in the range of −20 ° C. to −70 ° C., and the second cooling stage (200) is the first cooling stage (200). 15. The apparatus according to any one of claims 12 to 14, wherein the apparatus is separate from the cooling stage (100).