KR101009853B1 - Natural gas liquefaction process with refrigerant separator - Google Patents

Abstract

PURPOSE: A natural gas liquefaction process with a refrigerant separator is provided to improve the efficiency of a liquefaction process while easily managing the liquefaction process. CONSTITUTION: A natural gas liquefaction process with a refrigerant separator is comprised of steps: compressing a mixed-refrigerant by a compression unit; cooling the compressed refrigerant; dividing cooled refrigerant into a liquid refrigerant and a gas refrigerant; compressing and cooling the gas refrigerant; dividing the cooled into a heavy key refrigerant and a light key refrigerant through a distillation tower; cooling the light key refrigerant through a first heat exchange region; and dividing the light key refrigerant into liquid refrigerant and gas refrigerant.

Description

Natural gas liquefaction process with refrigerant separation {NATURAL GAS LIQUEFACTION PROCESS WITH REFRIGERANT SEPARATOR}

The present invention relates to a natural gas liquefaction process with refrigerant separation, and more specifically, by using a single closed loop refrigeration cycle employing a mixed refrigerant, the structure of the liquefaction process can be simplified, the system can be compact, and the operation of the liquefaction system is The present invention relates to a natural gas liquefaction process with refrigerant separation that is easy and has excellent efficiency of the liquefaction process.

Thermodynamic processes for liquefying natural gas to produce liquefied natural gas (LNG) have been developed since the 1970s to meet a variety of challenges, including the need for higher efficiency and greater capacity. In order to increase the efficiency and capacity of the liquefaction process, various attempts have been made to liquefy natural gas using different refrigerants or different cycles.

One of the most popular liquefaction processes in operation is the 'Propane Pre-cooled Mixed Refrigerant Process' (or C3 / MR Process). The basic structure of the C3 / MR process is as shown in FIG. As shown in FIG. 6, the feed gas is pre-cooled to approximately 238 K by a multi-stage propane (C3) Joule-Thomson (JT) cycle. The precooled feed gas is liquefied and sub-cooled to 123 K through heat exchange with a mixed refrigerant (MR) in a heat exchanger. The C3 / MR process has a disadvantage in that the liquefaction process is complicated and the operation of the liquefaction system is difficult because a refrigeration cycle employing a single refrigerant and a refrigeration cycle employing a mixed refrigerant are used.

One of the other successful liquefaction processes in operation is by Conoco Phillips, which is based on the Cascade process. As conceptually shown in FIG. 7, the liquefaction process of 'Conoco Phillips' uses three Joules using methane (C1), ethylene (C2), and propane (C3), which are pure-component refrigerants. It consists of a Thompson cycle. Since the liquefaction process does not use a mixed refrigerant, there is an advantage that the operation of the liquefaction process is safe, simple and reliable. However, there is a disadvantage in that the size of the liquefaction system is inevitably increased because an individual compressor, heat exchanger, etc. are required for each of the three cycles.

Another liquefaction process in operation is the 'Single Mixed Refrigerant Process' (or SMR Process). The basic structure of the SMR process is as shown in FIG. As shown in Fig. 8, the feed gas is liquefied through heat exchange with the mixed refrigerant in the heat exchange region. The SMR process uses one closed loop refrigeration cycle with mixed refrigerant. In this refrigeration cycle, the mixed refrigerant is compressed and precooled and then expanded after condensing the mixed refrigerant through heat exchange in the heat exchange zone. The expanded refrigerant flows back into the heat exchange zone to condense the precooled mixed refrigerant and liquefy the feed gas. This SMR process has the advantage that the system is compact due to its simple structure, but has the disadvantage that the efficiency of the liquefaction process is not good.

Therefore, the present invention has been made to solve the above problems, the problem of the present invention is to use a single closed loop refrigeration cycle employing a mixed refrigerant, the liquefaction process is simple, the system is compact and the operation of the liquefaction system is easy It is to provide a natural gas liquefaction process with excellent efficiency of the liquefaction process.

According to a preferred embodiment of the present invention for achieving the above object of the present invention, by using a single closed loop refrigeration cycle employing a mixed refrigerant to pre-cool natural gas through heat exchange with the refrigerant in the first heat exchange zone In the natural gas liquefaction process of liquefying the pre-cooled natural gas through the heat exchange with the refrigerant in the second heat exchange zone and the refrigerant separation, the closed loop refrigeration cycle, (a1) compressing the mixed refrigerant by a compression means, (a2) cooling the compressed refrigerant through step (a1), (b1) separating the refrigerant cooled through step (a2) into a gaseous refrigerant part and a liquid phase refrigerant part by an air liquid separator, and (b2) Compressing the separated gaseous refrigerant portion through step (b1), (b3) cooling the compressed refrigerant portion through step (b2), and (c) separating the cooled refrigerant portion through step (b3). sign Separating through a distillation column into a portion of heavy key refrigerant having a high boiling point and a portion of a light key refrigerant having a low boiling point according to the difference in boiling point, (d) separation through step (c) Cooling the cooled light key refrigerant portion through heat exchange in the first heat exchange zone, (e) separating the cooled light key refrigerant portion into a gaseous refrigerant portion and a liquid refrigerant portion through a main liquid separator, and (f) supplying the liquid phase refrigerant portion separated through (e) to the separation means, (g) cooling the gaseous phase refrigerant portion separated through step (e) through heat exchange in a first heat exchange zone, (h) condensing the refrigerant portion cooled through (g) through heat exchange in the second heat exchange zone, (i) expanding the condensed refrigerant portion via (h), (j) through (i) Second heat exchange zone Backflowing, (k) mixing the heavy key refrigerant portion separated in step (c) with the liquid refrigerant portion separated in step (b1), (l) the refrigerant mixed in step (k) Cooling the portion through heat exchange in the first heat exchange zone, (m) expanding the cooled refrigerant portion through step (l), and (n) the refrigerant passing through the second heat exchange region through step (j). Mixing the portion and the refrigerant portion expanded through step (m) and introducing it into the first heat exchange zone, and (o) compressing the refrigerant passing through the first heat exchange zone through step (n) in step (a1). Including the step of introducing.

In the step (c), the refrigerant may be separated into a heavy key refrigerant portion and a light key refrigerant portion through a distillation column as a separation means. In this case, step (c) may be supplied to the distillation column of the low temperature liquid refrigerant portion through step (f) to precisely separate the refrigerant into the heavy key refrigerant portion and the light key refrigerant portion.

And the step (c) comprises the steps of: (c1) separating the refrigerant portion cooled through step (b3) into a bottom stream and a top stream by means of a first gas-liquid separator; and (c2) the top separated through step (c1). Separating the stream back into the lower stream and the upper stream by a second gas-liquid separator, (c3) feeding the separated bottom stream to the first gas-liquid separator via step (c2), (c4) step (c2) Separating the upper stream separated through the third gas-liquid separator back into the lower stream and the upper stream, and (c5) feeding the lower stream separated through step (c4) to the second gas-liquid separator. have. In this case, the bottom stream separated through the step (c1) corresponds to the heavy key refrigerant part, and the top stream separated through the step (c4) corresponds to the light key refrigerant part, and the separation of the step (f) The liquid refrigerant portion may be supplied to the third gas-liquid separator.

Alternatively, the separating means of step (c) may include a plurality of gas-liquid separators connected in sequence. At this time, the separating means of step (c) is a first gas-liquid separator, the first gas-liquid separator which receives the coolant portion cooled through step (b3) and separates the lower stream and the upper stream, which is a heavy key refrigerant portion, A second gas-liquid separator receiving the top stream and separating the upper stream back into the lower stream and the upper stream, and a third gas-liquid receiving the upper stream separated through the second gas-liquid separator and separating the upper stream back into the upper stream which is a portion of the lower stream and the light key refrigerant. May comprise a separator. At this time, the lower stream separated by the second gas-liquid separator is supplied to the first gas-liquid separator, and the lower stream separated by the third gas-liquid separator is supplied to the second gas-liquid separator, and separated by the main gas-liquid separator. The liquid refrigerant portion may be supplied to the third gas-liquid separator.

Meanwhile, the natural gas liquefaction process according to the present invention may further include the step of separating the high boiling point liquid refrigerant portion into the side stream through the separation means and mixing the heavy key refrigerant portion separated through step (c). In addition, the natural gas liquefaction process according to the present invention may further comprise the step of separating the gaseous refrigerant portion having a low boiling point through the separation means into a side stream and mixing with the gaseous refrigerant portion separated through step (e). The mixed refrigerant may include methane (C1), ethane (C2), propane (C3), butane (C4), pentane (C5), and nitrogen (N2).

The natural gas liquefaction process according to the present invention is made of only one refrigeration cycle, so the liquefaction process is simple, the system is compact and the operation of the liquefaction system is easy. After separating into the light key portion, the natural gas is liquefied in the first heat exchange region with one refrigerant flow and liquefied with natural gas in the second heat exchange region with the other refrigerant flow, so the liquefaction efficiency of natural gas is excellent. It is effective.

1 is a flowchart illustrating a natural gas liquefaction process according to Embodiment 1 of the present invention.
2 is a flow chart showing a first modification of the separating means of FIG.
3 is a flow chart showing a second variant of the separating means of FIG.
4 is a flow chart showing a third modification of the separating means of FIG.
5 is a flowchart illustrating a natural gas liquefaction process according to Embodiment 2 of the present invention.
6 is a flowchart conceptually illustrating a conventional C3 / MR process.
7 is a flowchart conceptually illustrating a conventional cascade process.
8 is a flowchart conceptually illustrating a conventional SMR process.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. For reference, in the present description, the same numbers refer to substantially the same elements, and may be described by quoting contents described in other drawings under these rules. And it can be omitted that it is determined or repeated to those skilled in the art to which the present invention pertains.

Example 1

1 is a flowchart illustrating a natural gas liquefaction process according to Embodiment 1 of the present invention. The liquefaction process according to the present embodiment is a process for producing liquefied natural gas (LNG) by cooling natural gas to a liquefaction temperature by using a closed loop refrigeration cycle as shown in FIG. Can be applied. In particular, one closed loop refrigeration cycle employing mixed refrigerants or multi-component refrigerants is used to precool the natural gas through heat exchange with the refrigerant in the first heat exchange zone, and the refrigerant in the second heat exchange zone. It can be applied to the natural gas liquefaction process to liquefy the pre-cooled natural gas through heat exchange with.

Hereinafter, a liquefaction process according to an embodiment of the present invention applied to a natural gas liquefaction process including one refrigeration cycle as described above will be described with reference to FIG. 1. As shown in FIG. 1, the mixed refrigerant 101 is first compressed by the compressor 130. The compressed refrigerant 102 is cooled by the cooler 140. The coolant 103 cooled by the cooler 140 flows into the separating means 150 to a high boiling heavy key refrigerant portion 104 and a low boiling light key refrigerant portion 105. Are separated. The separating means 150 may be a distillation column (distillation column) that can separate the refrigerant into a heavy key refrigerant portion and a light key refrigerant portion, the main liquid separator 170 to be described later to supply a low-temperature refrigerant to such a distillation column It can serve as a kind of condenser. For reference, the aforementioned compressor 130 may be configured as a plurality of compressors and coolers connected in series. Compressing the refrigerant in multiple stages by connecting a plurality of compressors and coolers in series can reduce the required power of the compressor.

The light key refrigerant portion 105 thus separated is cooled through heat exchange in the first heat exchange region 161. Cooling of the coolant portion 105 is performed through heat exchange with the coolant 113 flowing into the first heat exchange region 161. The cooled refrigerant portion 106 is separated into a liquid refrigerant portion 107 and a gaseous refrigerant portion 108 by a main gas liquid separator 170. The main gas-liquid separator 170 may be a conventional vapor-liquid separator, that is, a conventional gas-liquid separator that separates a gaseous portion and a liquid state portion by using an equilibrium between gas and liquid.

The liquid refrigerant portion 107 thus separated is supplied to the aforementioned separation means 150. As a result, the aforementioned separating means 150 may be supplied with the low temperature liquid refrigerant part 107 to precisely separate the refrigerant 103 into the heavy key refrigerant part 104 and the light key refrigerant part 105. That is, the separation means 150 can separate the refrigerant more precisely by receiving the coolant cooled through heat exchange in the first heat exchange region 161, that is, by receiving cold heat from the outside. Thus, if the refrigerant is precisely separated, the performance of the refrigerant in each of the heat exchange areas 161 and 162 may be improved.

The gaseous refrigerant portion 108 separated by the main liquid separator 170 flows into the first heat exchange region 161 and is cooled. The cooling of the coolant portion 108 takes place through heat exchange with the coolant 113 entering the first heat exchange region 161. The coolant portion 109 thus cooled enters and condenses the second heat exchange region 162. The cooling of the refrigerant portion 109 is performed through heat exchange with the refrigerant 111 flowing into the second heat exchange region 162. The condensed refrigerant portion 110 is expanded by the expansion valve 181. The expanded refrigerant portion 111 flows into the second heat exchange region 162 to condense the other refrigerant 109 through heat exchange and to cool the natural gas 20 preheated through heat exchange in the first heat exchange region 161. Liquefy. For reference, the liquefied natural gas 30 is expanded by the expansion valve 183 and then introduced into the storage tank.

On the other hand, the heavy key refrigerant portion 104 separated by the separating means 150 described above is cooled through heat exchange in the first heat exchange region 161. Cooling of the coolant portion 104 is performed through heat exchange with the coolant 113 introduced into the first heat exchange region 161. The cooled refrigerant portion 114 is expanded by the expansion valve 182. The expanded refrigerant portion 115 is mixed with the refrigerant portion 112 that has passed through the second heat exchange region 162. The mixed refrigerant portion 113 enters the first heat exchange region 161. This refrigerant portion 113 flows into the first heat exchange region 161 to cool the other refrigerants 104, 105, 108 through heat exchange, precool the supplied natural gas 10, and then back to the compressor 130. Flows into).

FIG. 2 is a flowchart showing a first modification of the separating means of FIG. 1. As shown in FIG. 2, the separating means 150 of FIG. 1 may be configured by a plurality of gas-liquid separators 151, 152, and 153 sequentially connected. In detail, the coolant portion 103 cooled by the cooler 140 is separated by the first gas-liquid separator 151 into the lower stream 104 and the upper stream 121, which are heavy key refrigerant portions. Bottom stream 104 enters and cools first heat exchange zone 161 in the same manner as the heavy key refrigerant portion described above. The upper stream 121 is again separated into a lower stream 122 and an upper stream 123 by a second gas-liquid separator 152.

The lower stream 122 separated by the second gas-liquid separator 152 is supplied to the first gas-liquid separator 151, and the upper stream 123 is introduced into the third gas-liquid separator 153 and again the lower stream 124. And the upper stream 105 which is part of the light key refrigerant. The lower stream 124 thus separated is fed to a second gas-liquid separator 152 and the upper stream 105 enters and cools into the first heat exchange zone 161 in the same manner as the light key refrigerant portion described above. And the liquid refrigerant part 107 separated from the main gas liquid separator 170 is supplied to the third gas liquid separator 153.

Here, the first to third gas-liquid separators 151, 152, and 153 may be conventional gas-liquid separators similar to the main gas-liquid separator 170 described above. The number of gas-liquid separators described above is not limited to three as shown in FIG. 2. On the other hand, the above-mentioned separation means of the distillation column of FIG. 1 has the advantage that the liquefaction system can be configured more compactly than the plurality of gas-liquid separators. The number of gas-liquid separators required to separate the refrigerant into the heavy key refrigerant portion and the light key refrigerant portion as precisely as the distillation column may vary according to specific embodiments.

For example, if three or more gas-liquid separators are employed (in some cases, only two gas-liquid separators may be employed), between the first gas-liquid separator 151 and the second gas-liquid separator 152, or the second gas-liquid A gas-liquid separator may be added in the same structure between the separator 152 and the third gas-liquid separator 153. In addition, when a plurality of gas-liquid separators are not used to move the lower stream, which is usually in a liquid state, pumps 156 and 157 may be additionally installed as shown in FIG. 2.

Since the liquefaction process according to the present embodiment is made of only one refrigeration cycle as described above, the liquefaction process is simple, so that the system is compact and the operation of the liquefaction system is easy. In addition, in the liquefaction process according to the present embodiment, through the separation means consisting of a distillation column (or consisting of a plurality of gas-liquid separator), the refrigerant is precisely separated into a heavy key portion and a light key portion with a desired composition, and then one The refrigerant flow (i.e., low temperature refrigerant flow) precools the natural gas in the first heat exchange region, and the other refrigerant flow (i.e., cryogenic refrigerant flow) liquefies the natural gas in the second heat exchange region. It also has the advantage that the liquefaction efficiency of natural gas is also excellent.

FIG. 3 is a flowchart showing a second modification of the separating means of FIG. 1, and FIG. 4 is a flowchart showing a third modification of the separating means of FIG. 1. As shown in FIG. 3, a portion of the refrigerant, that is, a portion of the liquid refrigerant having a high boiling point, may be separated into the side stream 128 through the aforementioned separation means 150. The separated side stream 128 may be mixed with the separated heavy key refrigerant portion 104 by the separating means 150 and then introduced into the first heat exchange zone 161. Or a gaseous refrigerant separated by the main liquid-liquid separator 170 after a portion of the refrigerant, that is, a gaseous refrigerant portion having a low boiling point, is separated into the side stream 129 through the separating means 150 as shown in FIG. 4. May be mixed with the portion 108. The mixed refrigerant part flows into the first heat exchange region 161 and is cooled. In addition, both types of side streams 128 and 129 shown in FIGS. 3 and 4 may be applied to one liquefaction process. When the side stream is separated and mixed with a part of the refrigerant, the composition of the refrigerant obtained through the upper and lower portions of the separating means can be more precisely adjusted, and thus the cooling efficiency can be increased.

Example 2

5 is a flowchart showing a natural gas liquefaction process according to Embodiment 2 of the present invention. For reference, the same (or equivalent) reference numerals are given to the same (or equivalent) parts as the above-described configuration, and detailed description thereof will be omitted. As illustrated in FIG. 5, the liquefaction process according to the present embodiment is characterized in that the refrigerant is compressed twice. As described above, as shown in FIG. 5, the mixed refrigerant 101 is first compressed by the compressor 130. The compressed refrigerant 102 is cooled by the cooler 140.

The refrigerant 1031 cooled by the cooler 140 is separated into the gaseous refrigerant portion 1032 and the liquid refrigerant portion 1035 through the air liquid separator 172. The separated refrigerant portion 1032 is secondarily compressed by the compressor 132. The compressed refrigerant 1033 is secondarily cooled by the cooler 142. The coolant 1034 cooled by the cooler 142 flows into the separating means 150 described above and is separated into a heavy key coolant portion 1041 and a light key coolant portion 105. The heavy key refrigerant portion 1041 is then mixed with the liquid refrigerant portion 1035 separated by the air liquid separator 172 and then introduced into the first heat exchange zone 161 to cool. As such, the two-stage compression process can reduce the amount of work required to compress the low temperature refrigerant, thereby increasing the overall liquefaction efficiency.

The results of comparing the liquefaction process according to Example 1, the liquefaction process according to Example 2, the conventional C3 / MR process according to FIG. 6, and the conventional SMR process according to FIG. 8 are as follows. The table below shows the result of assuming that the required power per unit LNG (kWh / kg LNG) of the conventional SMR process is '1' (ie, 100%). In the liquefaction process according to Example 1, the mixed refrigerant includes methane (C1), ethane (C2), propane (C3), and nitrogen (N2). In the case of the liquefaction process according to Example 2, the mixed refrigerant is Methane (C1), ethane (C2), propane (C3), butane (C4), pentane (C5) and nitrogen (N2). And the separation means used for the liquefaction process of Examples 1 and 2 was set to the usual distillation column. As summarized in the table below, the liquefaction process according to the present embodiment has excellent efficiency even in comparison with a conventional liquefaction process. For reference, the comparison result may have some differences depending on how to determine the components of the mixed refrigerant in each process or how to determine the performance of the compressor.

division Performance Index (Unit:%)
[Required power ratio to unit LNG production]
Conventional SMR Process (see Figure 8)

100
Conventional C3 / MR Process (see Figure 6)

60.9
Liquefaction process according to Example 1 (see FIG. 1)

89.0
Liquefaction process according to Example 2 (see FIG. 5)

68.9

On the other hand, between the mixed refrigerant of the liquefaction process according to Example 1 and the mixed refrigerant of the liquefaction process according to Example 2 may have a difference in its components as described above. That is, the mixed refrigerant in the liquefaction process according to the second embodiment may further include butane (C4), pentane (C5). With respect to such component differences, the butane (C4) and pentane (C5) refrigerants may have excellent cooling efficiency in the low temperature region, but may be solidified in the ultra low temperature region where natural gas is liquefied. However, when the liquefaction process according to Example 2 is used, butane (C4) and pentane (C5) refrigerants can be precisely separated from the mixed refrigerant, so that a large amount of butane (C4) and pentane ( C5) It is possible to allow a small amount of butane (C4) and pentane (C5) refrigerants to flow through the refrigerant and in the cryogenic region where it may be solidified, thereby increasing the amount of butane (C4) and pentane. (C5) Since the coolant can be applied to the mixed coolant, the coolant performance in the low temperature region can be improved.

However, compared to the conventional liquefaction process, butane (C4) and pentane (C5) refrigerants, which are relatively increased, may be liquefied even with a slight pressure increase due to compression. The above problem can be solved because only the gas part can be further compressed after separation into the gas part and the liquid part. That is, in the liquefaction process of Example 2, since the refrigerant portion, which can be liquefied even with a slight compression, is first separated and then the gas portion is additionally compressed, butane (C4) and pentane ( C5) Refrigerant can be used, thereby increasing the cooling efficiency in the low temperature region and reducing the overall power consumption.

As described above, the present invention has been described with reference to preferred embodiments of the present invention, but a person of ordinary skill in the art does not depart from the spirit and scope of the present invention as set forth in the claims below. It will be understood that various modifications and variations can be made in the present invention. Therefore, the spirit of the present invention should be understood by the claims described below, and all equivalent or equivalent modifications thereof will belong to the scope of the present invention.

130: compressor 140: cooler
150 separation means 161 first heat exchange zone
162: second heat exchange zone 170: main gas liquid separator
181, 182, 183: expansion valve

Claims (9)

One closed loop refrigeration cycle employing a mixed refrigerant precools natural gas through heat exchange with the refrigerant in the first heat exchange zone and precools through heat exchange with the refrigerant in the second heat exchange zone. In the natural gas liquefaction process with liquefied natural gas and refrigerant separation,
The closed loop refrigeration cycle,
(a1) compressing the mixed refrigerant by compression means;
(a2) cooling the compressed refrigerant through the step (a1);
(b1) separating the refrigerant cooled through the step (a2) into a gaseous refrigerant portion and a liquid phase refrigerant portion by an air liquid separator;
(b2) compressing the separated gaseous refrigerant portion via step (b1);
(b3) cooling the compressed refrigerant portion through step (b2);
(c) a portion of the heavy key refrigerant having a high boiling point and a light key having a low boiling point according to a difference in boiling point through a distillation column, which is a separation means, of the refrigerant cooled through the step (b3). Separating into a refrigerant portion;
(d) cooling the light key refrigerant portion separated through step (c) through heat exchange in the first heat exchange zone;
(e) separating the cooled light key refrigerant portion into a gaseous refrigerant portion and a liquid phase refrigerant portion through a main liquid separator;
(f) supplying the liquid refrigerant portion separated through step (e) to the separation means for precise refrigerant separation by the separation means;
(g) cooling the vapor phase refrigerant portion separated through step (e) through heat exchange in the first heat exchange zone;
(h) condensing the refrigerant portion cooled through step (g) through heat exchange in the second heat exchange zone;
(i) expanding the portion of the refrigerant condensed through step (h);
(j) introducing a portion of the refrigerant expanded through step (i) into the second heat exchange zone;
(k) mixing the heavy key refrigerant portion separated through step (c) with the liquid refrigerant portion separated through step (b1);
(l) cooling the refrigerant portion mixed through step (k) through heat exchange in the first heat exchange zone;
(m) expanding the cooled refrigerant portion through step (l);
(n) mixing the refrigerant portion that has passed through the second heat exchange region through step (j) and the refrigerant portion that has expanded through step (m) and introducing it into the first heat exchange region; And
(o) introducing a refrigerant having passed through the first heat exchange zone through step (n) into the compression means of step (a1). delete delete delete delete delete The method according to claim 1,
Separating the liquid refrigerant portion having a high boiling point through the separation means into a side stream and mixing the heavy refrigerant portion separated through the step (c) with the refrigerant gas separation. . The method according to claim 1,
And separating the gaseous refrigerant portion having a lower boiling point through the separation means into a side stream and mixing the gaseous refrigerant portion separated through the step (e) with the refrigerant gas separation. The method according to claim 1,
The mixed refrigerant is methane (C1), ethane (C2), propane (C3), butane (C4), pentane (C5) and nitrogen (N2) characterized in that the natural gas liquefaction process with refrigerant separation.

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