KR101392750B1 - Natural gas liquefaction system and method using the same - Google Patents

Abstract

The natural gas liquefaction system of the present invention comprises precooling means; A gas-liquid separating means; A first heat exchange means; Second heat exchange means; A first expansion means; A second expansion means; A first mixed refrigerant conversion means; A cold refrigerant supply means; Natural gas supply means; And a mixer.
Further, the natural gas liquefaction method of the present invention comprises a first precooling step (S01); A first mixed refrigerant separation step (S02); A first introduction step (S03); A first expanded refrigerant forming step (S04); A second introduction step (S05); A second expanded refrigerant forming step (S06); And a second cooling step (S07).

Description

[0001] Natural gas liquefaction system and method [0002]

The present invention relates to a natural gas liquefaction system and a liquefaction process, and more particularly to a system and method for liquefying natural gas using refrigeration, liquefaction or solidification.

Thermodynamic processes for liquefying natural gas and producing liquefied natural gas (LNG) have been developed since the 1970s to meet a variety of challenges, including higher efficiency and greater capacity requirements. Various attempts have been made to liquefy natural gas using different refrigerants or different cycles in order to increase the efficiency and capacity of the liquefaction process. However, the number of liquefaction processes that are practically used is very high little.

One of the most widely deployed liquefaction processes during operation is the Propane Pre-cooled Mixed Refrigerant Process (or C3 / MR Process).

1 is a flow chart of a C3 / MR process.

As shown in Figure 1, the C3 / MR process pre-cooled natural gas to approximately 238 K by a multi-stage propane (C3) Joule-Thomson (JT) do. The precooled natural gas is liquefied and sub-cooled to 123 K by heat exchange with a mixed refrigerant (MR) in a heat exchanger.

In this case, the refrigerant cycle of the mixed refrigerant will be described in more detail. The mixed refrigerant is compressed to a high pressure, cooled, and introduced into the gas-liquid separator 10.

The mixed refrigerant is separated into light components and heavy components in the gas-liquid separator 10 and introduced into the primary heat exchanger 20, respectively, and the liquid mixed refrigerant is introduced into the primary heat exchanger 20 through the primary And is used for cooling the high temperature stream which is expanded when the heat exchange is completed and is introduced into the primary heat exchanger 20. [ The gaseous mixed refrigerant is introduced into the secondary heat exchanger 30, cooled, and further cooled through expansion to be used for cooling the secondary heat exchanger 30 and the primary heat exchanger 20.

The C3 / MR process is disadvantageous in that heat exchange efficiency of the heat exchangers 20, 30 is low.

Accordingly, various developments of a natural gas liquefaction system for solving the above problems are required.

US Patent No. 6691531 {2004.02.17}

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a natural gas liquefaction system and a liquefaction method capable of maximizing heat exchange efficiency and energy saving efficiency by improving the structure of a heat exchanger.

The natural gas liquefaction system according to the present invention comprises a pre-cooling means (100); A gas-liquid separating means (200) connected to the pre-cooling means (100); A first heat exchange unit 300 connected to the pre-cooling unit 100 and the gas-liquid separation unit 200; A second heat exchange unit (400) connected to the first heat exchange unit (300); A first expansion means (510) connected at one end to the first heat exchange means (300); A second expansion means (520) having both ends connected to the second heat exchange means (400); A first mixed refrigerant conversion means (600) connected to the pre-cooling means (100) and the first heat exchange means (300); Cooled refrigerant supply means (700) connected to the pre-cooling means (100); A natural gas supply means 800 connected to the pre-cooling means 100; And a mixing means 900 connecting the other end of the first expansion means 510 and the first heat exchange means 300 and connected to the second heat exchange means 400.

In one embodiment of the present invention, the first heat exchanging unit 300 is a first heat exchanger 310 connected to the pre-cooling unit 100 and the gas-liquid separating unit 200, And a third heat exchanger 410 connected to the first heat exchanger 310.

The first heat exchanging unit 300 may include a first heat exchanger 310 connected to the pre-cooling unit 100 and the gas-liquid separating unit 200, And a second heat exchanger 320 connected to the heat exchanger 310. The second heat exchanger 400 includes a third heat exchanger 410 connected to the second heat exchanger 320, And a fourth heat exchanger 420 connected to the heat exchanger 410.

According to another embodiment of the present invention, the first expansion means 510 has one end connected to the first heat exchanger 310 and the other end connected to the second heat exchanger 320, The second expansion means 520 is connected at one end to the third heat exchanger 410 and at the other end to the fourth heat exchanger 420.

The first mixed refrigerant conversion means 600 supplies the first mixed refrigerant to the precooling means 100. The precooled refrigerant supplying means 700 supplies the precooled refrigerant to the precooling means 100, The natural gas supply means 800 supplies natural gas to the precooling means 100 and the precooling means 100 uses the precooled refrigerant supplied from the first mixed refrigerant conversion means 600, Wherein the first mixed refrigerant and the natural gas respectively supplied from the means 100 and the natural gas supply means 800 are precooled and the gas-liquid separating means 200 is connected to the gas- The first heat exchanging means 300 separates the mixed refrigerant into a liquid first separating refrigerant and a gaseous second separating refrigerant, and the first heat exchanging means 300 separates the natural gas, the first separated refrigerant, Introducing a refrigerant, and using the mixed refrigerant, The first separating refrigerant and the second separating refrigerant are cooled so that the first separating refrigerant is cooled to a higher temperature than the natural gas and the second separating refrigerant, The first heat exchanging means (300) expands the first separating refrigerant introduced from the first heat exchanging means (300) to form a first expanded refrigerant, and the second heat exchanging means (400) The second separated refrigerant is cooled by using the second expanded refrigerant to cool the natural gas and the second separated refrigerant so that the second separated refrigerant is cooled to a higher temperature than the natural gas, And the second expansion means (520) forms the second expanded refrigerant, which is formed by expanding the second separated refrigerant introduced from the second heat exchange means (400), into the second heat exchange means (400) ), And the mixed water (900) is configured to mix the part of the first expanded refrigerant introduced from the first expansion means (510) and the second expanded refrigerant introduced from the second heat exchange means (400) To the heat exchanging means (300).

Further, the cold refrigerant is a single refrigerant or a second mixed refrigerant.

The first mixed refrigerant conversion means 600 sequentially compresses and cools the mixed refrigerant introduced from the first heat exchange means 300 to convert the mixed refrigerant into a first mixed refrigerant and supplies the first mixed refrigerant to the pre- (100).

Also, a first precooling step (S01) for precooling the first mixed refrigerant and the natural gas; A first mixed refrigerant separation step (S02) for separating the first mixed refrigerant into a liquid first separating refrigerant and a gaseous second separating refrigerant, respectively; A first introduction step (S03) of introducing the natural gas, the first separation refrigerant and the second separation refrigerant into the first heat exchange zone without mixing; A first expanded refrigerant forming step (S04) of introducing and expanding the first separated refrigerant into the first expansion region to form the first expanded refrigerant into the first expanded refrigerant; A second introduction step (S05) of introducing the natural gas and the second separated refrigerant into the second heat exchange zone without mixing; A second expanded refrigerant forming step (S06) of introducing and expanding the second separated refrigerant into the second expansion region to form the second expanded refrigerant into the second expanded refrigerant; The second expanded refrigerant is supplied to the second heat exchange zone to cool the natural gas and the second separated refrigerant introduced into the second heat exchange zone, and the second separated refrigerant is cooled less than the natural gas A subcooling step (S07) of forming a liquefied natural gas by supercooling the natural gas; A mixed refrigerant forming step (S08) of mixing the second expanded refrigerant and the first expanded refrigerant to form a mixed refrigerant; And supplying the mixed refrigerant to the first heat exchange zone to cool the natural gas, the first separation refrigerant, and the second separation refrigerant introduced into the first heat exchange zone, And a cooling step (S09) for cooling the natural gas and the second separation refrigerant to a lower temperature and forming the same at a higher temperature.

Also, the first precooling step (S01) pre -cools the first mixed refrigerant and the natural gas using a single refrigerant or a second mixed refrigerant.

The natural gas liquefaction method may further include a conversion step (S10) of sequentially compressing and cooling the mixed refrigerant to convert the mixed refrigerant into a first mixed refrigerant; And a second precooling step (S11) for precooling the first mixed refrigerant and the natural gas; (S12) of repeating the first mixed refrigerant separation step (S02) to the second precooling step (S11) one cycle at one time.

Also, the second precooling step (S11) uses the single refrigerant or the second mixed refrigerant to pre-cool the first mixed refrigerant and the natural gas.

Accordingly, the present invention has the effect of reducing energy consumption for liquefying natural gas by reducing the temperature difference between the refrigerant introduced into the first heat exchanging means and the natural gas.

1 is a flow chart illustrating a conventional C3 / MR process
2 is a schematic view of a natural gas liquefaction system
3 is a schematic view of a natural gas liquefaction system
Fig. 4 is a schematic diagram of a natural gas liquefaction system
FIG. 5 is a schematic view showing a natural gas liquefaction system
FIG. 6 is a schematic view showing a natural gas liquefaction method

Hereinafter, the technical idea of the present invention will be described more specifically with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the technical concept of the present invention, are incorporated in and constitute a part of the specification, and are not intended to limit the scope of the present invention.

2 is a natural gas liquefaction system according to Embodiment 1 of the present invention.

2, the natural gas liquefaction system 1000a according to the first embodiment of the present invention includes a precooling means 100, a gas-liquid separating means 200, a first heat exchanging means 300, a second heat exchanging means 400, the first expansion means 510, the second expansion means 520, the first mixed refrigerant conversion means 600, the cold refrigerant supply means 700, the natural gas supply means 800, the mixing means 900, .

First, the components of the natural gas liquefaction system 1000a according to the first embodiment of the present invention are connected through a plurality of pipelines.

The first pipe is connected to the natural gas supply means 800, the pre-cooling means 100, the first heat exchanging means 300 and the second heat exchanging means 400 in sequence and the pre-cooling means 100, the first heat exchanging means 300, and the second heat exchange means 400, respectively.

The second pipe is in the form of a cycle, and connects the precooled refrigerant supply means 700 and the precooling means 100.

The third piping is sequentially connected to the first mixed refrigerant conversion means 600, the precooling means 100 and the gas-liquid separating means 200 through the precooling means 100.

The fourth piping is sequentially connected to the gas-liquid separating means 200, the first heat exchanging means 300, the first expanding means 510, the mixing means 900, the first heat exchanging means 300, (600), and is connected to the first heat exchanger (300) through the second heat exchanger (300).

Particularly, in the fourth piping, in the connection of the gas-liquid separating means 200, the first heat exchanging means 300 and the first expansion means, the pipe is connected to the center of the first heat exchanging means 300 And is then discharged to the lower side or the upper side of the first heat exchanging means 300 and connected to the first expansion means 510.

That is, the fourth pipe is formed so as not to penetrate through the first heat exchanging means 300 in a straight line.

The fifth piping sequentially passes through the gas-liquid separating means 200, the first heat exchanging means 300, the second heat exchanging means 400, the second expanding means 520, the second heat exchanging means 400, the mixing means 900 And is connected to the first heat exchange means 300 through the second heat exchange means 400 and is connected to the second heat exchange means 400 twice.

Next, the components of the natural gas liquefaction system according to the first embodiment of the present invention will be described in detail.

The first mixed refrigerant conversion means 600 includes a first MR compressor 610 and a first MR cooler 620.

The first MR compressor 610 comprises a three-stage compressor to compress the first mixed refrigerant.

The first MR cooler 620 introduces the first mixed refrigerant compressed in the first MR compressor 610, cools it, and supplies it to the pre-cooling means 100.

That is, the first mixed refrigerant conversion means 600 is configured to compress the first mixed refrigerant, cool it, and supply it to the pre-cooling means 100.

The quench refrigerant supply means 700 is composed of a C3 compressor 710, a C3 cooler 720, and a C3 expansion valve 730.

The quench refrigerant supply unit 700 sequentially compresses, cools, and expands a single refrigerant by using the C3 compressor 710, the C3 condenser 720, and the C3 expansion valve 730, and supplies the compressed refrigerant to the pre- do.

At this time, propane is used as a single refrigerant, the C3 compressor 710 is composed of a four-stage compressor, and the C3 expansion valve 730 is composed of a four-stage line-Thomson valve.

The natural gas supply means 800 is a tank for storing natural gas, and supplies the stored natural gas to the pre-cooling means 100.

The pre-cooling means 100 independently introduces the first mixed refrigerant from the first mixed refrigerant conversion means 600, the single refrigerant from the refrigerant supply means 700 for cooling, and the natural gas from the natural gas supply means 800 .

In addition, the pre-cooling means 100 uses a single refrigerant to pre-cool the first mixed refrigerant and the natural gas.

The gas-liquid separating means (200) introduces the first mixed refrigerant from the pre-cooling means (100) and separates the liquid separated first separated refrigerant and the gaseous second separated refrigerant, respectively.

The first heat exchanging means 300 is constituted by one first heat exchanger 310 and the natural gas is independently introduced from the preheating means 100 and the first separated refrigerant and the second separated gas The first separation refrigerant and the second separation refrigerant are cooled using the mixed refrigerant introduced into the first heat exchange means 300 through various post-processes, Is cooled to a higher temperature than the natural gas and the second separate refrigerant.

Here, the mix refrigerant will be described below.

The first expansion means 510 is an expansion valve disposed on the lower side or the upper side of the first heat exchanger 310. The first expansion means 510 is connected to the center portion of the first heat exchanger 310 by the fourth piping, The first separated refrigerant is forcedly introduced and expanded to form the first expanded refrigerant.

That is, the first expansion means 510 forcibly removes the first separated refrigerant introduced into the first heat exchanger 310 from the center of the first heat exchanger 310.

The second heat exchanger 400 is composed of one third heat exchanger 410. The second heat exchanger 310 introduces the second separated refrigerant and the natural gas independently and performs various post- The second separated refrigerant is cooled by using the second expanded refrigerant introduced into the second heat exchange means 400 so that the second separated refrigerant is cooled to a higher temperature than the natural gas and the natural gas is sub- It forms natural gas.

Here, the second expanded refrigerant will be described below.

The second expansion means (520) is an expansion valve. The second expansion refrigerant is formed by introducing and expanding the second separated refrigerant from the third heat exchanger (410) to form the second expansion refrigerant, and the second expansion refrigerant is introduced into the third heat exchanger Supply.

The mixing means 900 mixes the mixed refrigerant formed by mixing the first expanded refrigerant introduced from the first expansion means 510 and the second expanded refrigerant introduced from the third heat exchanger 410 into the first heat exchanger 310, .

Accordingly, the present invention is characterized in that the final discharge temperature difference between the mixed refrigerant introduced from the mixing means 900 into the first heat exchanging means 300 and the natural gas cooled by the first heat exchanging means 300 and the second separated refrigerant becomes dark The heat exchange efficiency is increased, and energy consumption for liquefying natural gas can be reduced.

On the other hand, the first mixed refrigerant conversion means 600 sequentially compresses and cools the mixed refrigerant introduced from the first heat exchanger 310 and supplies the refrigerant to the pre-cooling means 100 again.

That is, the first mixed refrigerant converting means 600 converts the mixed refrigerant into the first mixed refrigerant and supplies it to the pre-cooling means 100 again.

Experimental results of the process of liquefying natural gas using the natural gas liquefaction system 1000a according to the first embodiment of the present invention are as follows.

Component Mol% Nitrogen 0.22 Methane 91.33 Ethane 5.36 Propane 2.14 I-butane 0.46 n-butane 0.47 I-pentane 0.01 n-pentane 0.01

Pressure (Bar) 53 Temperature (ㅀ C) 45 Flow Rate (kmol / hr) 35065

The natural gas has the composition shown in Table 1 and has the pressure and temperature shown in Table 2 and is sequentially supplied to the preheating means 100, the first heat exchanging means 300, the second heat exchanging means 400, Lt; / RTI >

The single refrigerant (propane) is compressed to four stages by the C3 compressor 710 of the quench refrigerant supply means 700 and has a pressure of 16.4 bar and is expanded to four stages by the C3 expander 730, , 4.2 bar, 2.5 bar, 1.114 bar, and is supplied to the pre-cooling means 100.

 mole fraction (-) N2 0.0827 C1 0.4555 C2 0.3062 C3 0.1555

The first mixed refrigerant has the composition shown in Table 3 and is compressed in three stages by the first MR compressor 610 of the first mixed refrigerant supply device 600 to have a pressure of 60 bar, 100, and then separated into a liquid first separating refrigerant and a liquid second separating refrigerant through a gas-liquid separator 200. [

The first separated refrigerant is introduced into the first expansion means (510) through the first heat exchange means (300) and formed into the first expanded refrigerant having a pressure of 4 bar, and then introduced into the mixer (900).

The second separated refrigerant is introduced into the second expansion means 510 through the second heat exchange means 400 and expanded to form the second expanded refrigerant and then introduced into the mixer 900 through the second heat exchange means 400 do.

The mixer 900 introduces the mixed refrigerant formed by mixing the first expanded refrigerant and the second expanded refrigerant into the first heat exchange means 300.

Meanwhile, the first separation refrigerant, the second separation refrigerant, and the natural gas introduced into the first heat exchange unit 300 are cooled by the mixed refrigerant introduced from the mixer 900.

At this time, the temperature difference of the first refrigerant introduced into the first heat exchanging means 300, the second separated refrigerant, and the natural gas and the mixed refrigerant introduced into the first heat exchanging means 300 through various processes Was maintained at 4K, and the power consumed to liquefy the natural gas when maintaining the temperature difference was 203900 KW.

The power consumed to liquefy the natural gas using the general C3 / MR process was 210700 KW, and the natural gas liquefaction system according to Example 1 of the present invention was able to reduce the electric power by 6800 KW as compared with the general C3 / MR process .

The Applicant has empirically and experimentally derived experimental results as described above.

3 is a natural gas liquefaction system according to Embodiment 2 of the present invention.

As shown in FIG. 3, the natural gas liquefaction system 1000b according to the second embodiment of the present invention is constructed in the same manner as the natural gas liquefaction system 1000a according to the first embodiment of the present invention, The fourth piping, the fifth piping, the first heat exchanging means 300 and the second heat exchanging means 400 are configured differently.

The first heat exchanger 300 includes a first heat exchanger 310 and a second heat exchanger 320. The second heat exchanger 400 includes a third heat exchanger 410 and a fourth heat exchanger 420).

The first piping is sequentially connected to the natural gas supply means 800, the pre-cooling means 100, the first heat exchanger 310, the second heat exchanger 320, the third heat exchanger 410, the fourth heat exchanger 420 And is connected to the precooling means 100, the first heat exchanger 310, the second heat exchanger 320, the third heat exchanger 410, and the fourth heat exchanger 420, respectively.

The fourth piping sequentially includes a gas-liquid separating unit 200, a first heat exchanger 310, a first expansion unit 510, a mixing unit 900, a second heat exchanger 320, a first heat exchanger 310, And the first refrigerant conversion means 600 is connected to the second heat exchanger 320 and is connected to the first heat exchanger 310 through the second heat exchanger 310 twice.

The fifth piping is sequentially connected to the gas-liquid separating means 200, the first heat exchanger 310, the second heat exchanger 320, the third heat exchanger 410, the second expansion means 520, the fourth heat exchanger The second heat exchanger 320 and the fourth heat exchanger 420 are connected to the third heat exchanger 410 and the mixing means 900 and connected to the first heat exchanger 310, the second heat exchanger 320 and the fourth heat exchanger 420, And is connected to the third heat exchanger 410 two times.

The natural gas liquefaction system 1000b according to the second embodiment of the present invention is configured such that the first heat exchanger 300 includes the first heat exchanger 310 and the second heat exchanger 320, The same effects as those of the first heat exchanging means 300 according to the first embodiment can be obtained.

In the natural gas liquefaction system 1000b according to the second embodiment of the present invention, the second heat exchanger 400 includes the third heat exchanger 410 and the fourth heat exchanger 420, The same effect as the configuration of the second heat exchanging means 400 according to Example 1 can be obtained.

4 is a natural gas liquefaction system according to Embodiment 3 of the present invention.

4, the natural gas liquefaction system 1000c according to the third embodiment of the present invention is constructed in the same manner as the natural gas liquefaction system 1000a according to the first embodiment of the present invention, 700 are configured differently.

The quench refrigerant supply means 700 includes a second MR compressor 740, a second MR cooler 750 and a second MR expansion valve 760 to provide a second mixed refrigerant to the precooling means 100, do.

That is, the quench refrigerant supply unit 700 supplies the second mixed refrigerant to the precooling unit 100 using the second MR compressor 740, the second MR cooler 750, and the second MR expansion valve 760.

Here, the second mixed refrigerant is formed of the same material as the first mixed refrigerant.

5 is a natural gas liquefaction system according to Embodiment 4 of the present invention.

5, the natural gas liquefaction system 1000d according to the fourth embodiment of the present invention is constructed in the same manner as the natural gas liquefaction system 1000b according to the second embodiment of the present invention, Cooled refrigerant supply unit according to the third embodiment of the present invention.

6 is a method for liquefying natural gas according to the present invention.

6, the natural gas liquefaction method according to the present invention includes a first precooling step S01, a first mixed refrigerant separation step S02, a first introduction step S03, a first expanded refrigerant forming step S04), the second introduction step S05, the second expansion refrigerant formation step S06, the subcooling step S07, the mix refrigerant formation step S08, the cooling step S09, the conversion step S10, A step S11, and a repeating cycle step S12.

Referring to FIG. 6, the natural gas liquefaction method according to the present invention will be described in detail.

First, a single refrigerant or a second mixed refrigerant is used to pre-cool the first mixed refrigerant and the natural gas supplied from the outside. This corresponds to the first precooling step S01 shown in Fig.

Next, the pre-cooled first mixed refrigerant is separated into the liquid first separating refrigerant and the gaseous second separating refrigerant, respectively. This corresponds to the first mixed refrigerant separation step (S02) shown in FIG.

Next, the pre-cooled natural gas, the first separated refrigerant, and the second separated refrigerant are introduced into the first heat exchange zone without mixing. This corresponds to the first introduction step (S03) shown in Fig. On the other hand, the natural gas, the first separated refrigerant, and the second separated refrigerant introduced into the first heat exchange region are cooled by the mixed refrigerant, which will be described below.

Next, the first separated refrigerant is introduced into the first expansion region and expanded to form the first expanded refrigerant. This corresponds to the first expanded refrigerant forming step (S04) shown in Fig.

Next, the natural gas and the second separated refrigerant are introduced into the second heat exchange zone without mixing. This corresponds to the second introduction step (S05) shown in Fig.

Next, the second separated refrigerant is introduced into the second expansion region and expanded to form the second expanded refrigerant. This corresponds to the second expanded refrigerant forming step (S06) shown in Fig.

Next, the second expanded refrigerant is supplied to the second heat exchange zone to cool the natural gas and the second separated refrigerant introduced into the second heat exchange zone in the second introduction step (S06) Cooled to a higher temperature, and the natural gas is sub-cooled to form liquefied natural gas. This corresponds to the supercooling step (S07) shown in Fig.

Next, the second expanded refrigerant used in the subcooling step (S07) and the first expanded refrigerant formed in the first expanded refrigerant forming step (S04) are mixed to form a mixed refrigerant. This corresponds to the mixed refrigerant forming step (S08) shown in FIG.

Next, the mixed refrigerant is supplied to the first heat exchange zone to cool the natural gas, the first separated refrigerant, and the second separated refrigerant introduced into the first heat exchange zone in the first introduction step (S03) Is cooled less than the natural gas and the second separate refrigerant to form the first separated refrigerant at a high temperature. This corresponds to the cooling step (S09) shown in Fig.

Next, the mixed refrigerant introduced into the first heat exchange region is introduced into the conversion region, compressed and cooled to be converted into the first mixed refrigerant. This corresponds to the conversion step S10 shown in Fig.

Next, using the single refrigerant or the second mixed refrigerant, the first mixed refrigerant generated in the conversion step (S10) and the natural gas supplied from the outside are pre-cooled. This corresponds to the second pre-cooling step S11 shown in Fig.

Next, the first mixed refrigerant separation step (S02) to the second precooling step (S11) are repeated one or more times as one cycle. This corresponds to the iteration cycle step S12 shown in Fig.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1000a, b, c, d: natural gas liquefaction system according to the present invention
100: preheating means
200: gas-liquid separating means
300: first heat exchanging means
310: first heat exchanger 320: second heat exchanger
400: second heat exchanging means
410: third heat exchanger 420: fourth heat exchanger
510: first expansion means 520: second expansion means
600: first mixed refrigerant conversion means
700: Refrigerated refrigerant supply means
800: natural gas supply means
900: mixing means

Claims (11)

Pre-cooling means (100);
A gas-liquid separating means (200) connected to the pre-cooling means (100);
A first heat exchange unit 300 connected to the pre-cooling unit 100 and the gas-liquid separation unit 200;
A second heat exchange unit (400) connected to the first heat exchange unit (300);
A first expansion means (510) connected at one end to the first heat exchange means (300);
A second expansion means (520) having both ends connected to the second heat exchange means (400);
A first mixed refrigerant conversion means (600) connected to the pre-cooling means (100) and the first heat exchange means (300);
Cooled refrigerant supply means (700) connected to the pre-cooling means (100);
A natural gas supply means 800 connected to the pre-cooling means 100; And
And mixing means 900 connecting the other end of the first expansion means 510 to the first heat exchange means 300 and connected to the second heat exchange means 400,
The first heat exchange means (300)
A first heat exchanger 310 connected to the pre-cooling means 100 and the gas-liquid separator 200, and a second heat exchanger 320 connected to the first heat exchanger 310,
The second heat exchange means (400)
A third heat exchanger 410 connected to the second heat exchanger 320 and a fourth heat exchanger 420 connected to the third heat exchanger 410.
delete delete The method according to claim 1,
The first expansion means (510)
One end is connected to the first heat exchanger 310 and the other end is connected to the second heat exchanger 320,
The second expansion means (520)
One end of which is connected to the third heat exchanger (410) and the other end is connected to the fourth heat exchanger (420).
The method according to claim 1,
The first mixed refrigerant conversion means (600)
The first mixed refrigerant is supplied to the precooling means (100)
The quench refrigerant supply means (700)
The pre-cooling refrigerant is supplied to the pre-cooling means (100)
The natural gas supply means (800)
Natural gas is supplied to the pre-cooling means (100)
The pre-cooling means (100)
The first mixed refrigerant and the natural gas supplied from the precooling means 100 and the natural gas supplying means 800 are precooled using the precooled refrigerant supplied from the first mixed refrigerant converting means 600 ,
The gas-liquid separating means (200)
Separating the first mixed refrigerant introduced from the pre-cooling means (100) into a liquid first separated refrigerant and a gaseous second separated refrigerant,
The first heat exchange means (300)
The natural gas, the first separated refrigerant, and the second separated refrigerant are introduced from the pre-cooling means 100, and the natural gas, the first separated refrigerant, and the second separated refrigerant are cooled using the mixed refrigerant, , The first separated refrigerant is cooled to a higher temperature than the natural gas and the second separated refrigerant,
The first expansion means (510)
The first expanded refrigerant introduced from the first heat exchange means (300) is expanded to form the first expanded refrigerant,
The second heat exchange means (400)
The natural gas and the second separated refrigerant are introduced from the first heat exchange means 300 and the natural gas and the second separated refrigerant are cooled using the second expanded refrigerant, Forming a high temperature by cooling less than natural gas, subcooling said natural gas to form liquefied natural gas,
The second expansion means (520)
The second expanded refrigerant formed by expanding the second separated refrigerant introduced from the second heat exchanging means (400) is supplied to the second heat exchanging means (400)
The mixing means (900)
The mixed refrigerant formed by mixing a part of the first expanded refrigerant introduced from the first expansion means 510 and the second expanded refrigerant introduced from the second heat exchange means 400 into the first heat exchange means 300 ). ≪ / RTI >
6. The method of claim 5, wherein the cold refrigerant
Wherein the refrigerant is a single refrigerant or a second mixed refrigerant.
The refrigeration system according to claim 5, wherein the first mixed refrigerant conversion means (600)
And the first mixed refrigerant is supplied to the precooling means (100) by sequentially compressing and cooling the mixed refrigerant introduced from the first heat exchanging means (300) into the first mixed refrigerant.
A first precooling step (S01) for precooling the first mixed refrigerant and the natural gas;
A first mixed refrigerant separation step (S02) for separating the first mixed refrigerant into a liquid first separating refrigerant and a gaseous second separating refrigerant, respectively;
A first introduction step (S03) of introducing the natural gas, the first separation refrigerant and the second separation refrigerant into the first heat exchange zone without mixing;
A first expanded refrigerant forming step (S04) of introducing and expanding the first separated refrigerant into the first expansion region to form the first expanded refrigerant into the first expanded refrigerant;
A second introduction step (S05) of introducing the natural gas and the second separated refrigerant into the second heat exchange zone without mixing;
A second expanded refrigerant forming step (S06) of introducing and expanding the second separated refrigerant into the second expansion region to form the second expanded refrigerant into the second expanded refrigerant; And
The second expanded refrigerant is supplied to the second heat exchange zone to cool the natural gas and the second separated refrigerant introduced into the second heat exchange zone, and the second separated refrigerant is cooled less than the natural gas A subcooling step (S07) of forming a liquefied natural gas by supercooling the natural gas;
A mixed refrigerant forming step (S08) of mixing the second expanded refrigerant and the first expanded refrigerant to form a mixed refrigerant;
Wherein the mixed refrigerant is supplied to the first heat exchange zone to cool the natural gas, the first separation refrigerant and the second separation refrigerant introduced into the first heat exchange zone, (S09) which is cooled and formed at a higher temperature than the gas and the second separated refrigerant (S09).
9. The method according to claim 8, wherein the first precooling step (S01)
Wherein the first mixed refrigerant and the natural gas are precooled by using a single refrigerant or a second mixed refrigerant.
9. The method of claim 8, wherein the natural gas liquefaction process
A converting step (S10) of sequentially compressing and cooling the mixed refrigerant to convert it into a first mixed refrigerant; And
A second precooling step (S11) for precooling the first mixed refrigerant and the natural gas;
(S12) of repeating the first mixed refrigerant separation step (S02) to the second precooling step (S11) one cycle at a time.
11. The method according to claim 10, wherein the second pre-cooling step (S11)
Wherein the first mixed refrigerant and the natural gas are precooled by using a single refrigerant or a second mixed refrigerant.

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