WO2014003449A1 - System and method for liquefying natural gas - Google Patents

Description

Natural gas liquefaction system and liquefaction method

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

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. little.

One of the most popular liquefaction processes in 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 FIG. 1, the C3 / MR process is pre-cooled with natural gas to approximately 238 K by a multi-stage propane (C3) Joule-Thomson (JT) cycle. do. The precooled natural gas is liquefied and sub-cooled to 123 K through heat exchange with a mixed refrigerant (MR) in a heat exchanger.

At this time, to describe the refrigeration cycle of the mixed refrigerant in more detail, the mixed refrigerant is compressed to a high pressure and then cooled, is introduced into the gas-liquid separator (10).

The mixed refrigerant is separated into a light component and a heavy component in the gas-liquid separator 10 and introduced into the primary heat exchanger 20, respectively, and the mixed refrigerant of the liquid phase is primary in the primary heat exchanger 20. When the heat exchange is completed, the expansion is used to cool the hot stream introduced into the primary heat exchanger (20). The gaseous mixed refrigerant is introduced into the secondary heat exchanger 30 to be 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 has a low heat exchange efficiency of the heat exchangers 20 and 30.

As a related technology, US 6691531 B1 is proposed, and various developments of a natural gas liquefaction system are required to solve the above problems.

(Prior art document)

(Patent Document 1) US 6691531 B1 (2004.02.17)

The present invention has been made to solve the above problems, by improving the configuration of the heat exchanger, to provide a natural gas liquefaction system and liquefaction method that can maximize heat exchange efficiency and energy saving efficiency.

Natural gas liquefaction system according to the present invention is a pre-cooling means (100); Gas-liquid separation means 200 connected to the precooling means 100; First heat exchange means (300) connected to the precooling means (100) and the gas-liquid separation means (200), respectively; Second heat exchange means (400) connected to the first heat exchange means (300); First expansion means (510) having one end connected to the first heat exchange means (300); Second expansion means 520 having both ends connected to the second heat exchange means 400; First mixed refrigerant conversion means (600) connected to the precooling means (100) and the first heat exchange means (300), respectively; Precooling supply means (700) connected to the precooling means (100); Natural gas supply means (800) connected to the precooling means (100); And a 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.

In addition, as an embodiment of the present invention, the first heat exchange means 300 is a first heat exchanger 310 connected to the precooling means 100 and the gas-liquid separation means 200, and the second heat exchange means. 400 may be composed of a third heat exchanger 410 connected to the first heat exchanger 310.

In addition, as another embodiment of the present invention, the first heat exchange means 300 is a first heat exchanger 310 connected to the precooling means 100 and the gas-liquid separation means 200, and the first The second heat exchanger 320 is connected to the heat exchanger 310, the second heat exchange means 400 is a third heat exchanger 410 connected to the second heat exchanger 320, and the third heat exchange And a fourth heat exchanger 420 connected with the group 410.

In addition, as another embodiment of the present invention, one end of the first expansion means 510 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 has one end connected with the third heat exchanger 410 and the other end connected with the fourth heat exchanger 420.

In addition, the first mixed refrigerant conversion means 600 supplies a first mixed refrigerant to the precooling means 100, the precooling refrigerant supply means 700 supplies a 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 precooling refrigerant supplied from the first mixed refrigerant converting means 600. Precooling the first mixed refrigerant and the natural gas supplied from the means 100 and the natural gas supply means 800, and the gas-liquid separation means 200 is the first introduced from the precooling means 100. The mixed refrigerant is separated into a liquid first separation refrigerant and a gaseous second separation refrigerant, and the first heat exchange means 300 separates the natural gas, the first separation refrigerant, and the second separation from the precooling means 100. Introducing a refrigerant and using the mixed refrigerant, the natural gas, Cooling the first separated refrigerant and the second separated refrigerant, but cooling the first separated refrigerant less than the natural gas and the second separated refrigerant to form a high temperature, the first expansion means (510) Expanding the first separated refrigerant introduced from the first heat exchange means 300 to form a first expansion refrigerant, the second heat exchange means 400 is the natural gas, the second from the first heat exchange means 300 A separate refrigerant is introduced, and the second expanded refrigerant is cooled by using a second expansion refrigerant, but the second separated refrigerant is cooled less than the natural gas to be formed at a high temperature, and the natural gas is supercooled. To form a liquefied natural gas, and the second expansion means 520 expands the second separated refrigerant introduced from the second heat exchange means 400 to the second expansion refrigerant 400. ) And the mixed water 900, the mixed refrigerant formed by mixing a portion of the first expansion refrigerant introduced from the first expansion means 510 and the second expansion refrigerant introduced from the second heat exchange means 400 may include the first mixed refrigerant. Supply to the heat exchange means (300).

In addition, the precooling refrigerant is a single refrigerant or a second mixed refrigerant.

In addition, the first mixed refrigerant converting means 600 converts the mixed refrigerant introduced from the first heat exchange means 300 into a first mixed refrigerant by sequentially compressing and cooling the first mixed refrigerant, and converts the first mixed refrigerant into the precooling means. Supply to (100).

In addition, the first pre-cooling step (S01) for pre-cooling the first mixed refrigerant and natural gas; A first mixed refrigerant separation step (S02) for separating the first mixed refrigerant into a liquid first separation refrigerant and a gaseous second separation refrigerant, respectively; A first introduction step (S03) of introducing the natural gas, the first separated refrigerant, and the second separated refrigerant into the first heat exchange zone without mixing; A first expansion refrigerant forming step (S04) of introducing the first separation refrigerant into a first expansion region and expanding the first separation refrigerant to form the first expansion refrigerant; A second introduction step (S05) of introducing the natural gas and the second separated refrigerant into a second heat exchange zone without mixing; A second expanded refrigerant forming step (S06) of introducing the second separated refrigerant into a second expanded region and expanding the same to form a second expanded refrigerant; Supplying the second expanded refrigerant to the second heat exchange zone to cool the natural gas and the second separated refrigerant introduced into the second heat exchange zone, but cooling the second separated refrigerant less than the natural gas. Forming a high temperature and subcooling the natural gas to form a liquefied natural gas (S07); A mix 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 separated refrigerant, and the second separated refrigerant introduced into the first heat exchange zone, wherein the first separated refrigerant is It comprises a; cooling step (S09) to form a high temperature by cooling less than the natural gas and the second separated refrigerant.

In addition, the first precooling step S01 precools the first mixed refrigerant and the natural gas by using a single refrigerant or a second mixed refrigerant.

In addition, the natural gas liquefaction method is a conversion step of converting the mixed refrigerant to the first mixed refrigerant by sequentially cooling and cooling (S10); And a second precooling step (S11) of precooling the first mixed refrigerant and the natural gas. And a repeating cycle step (S12) of repeating the first mixed refrigerant separation step (S02) to the second precooling step (S11) one or more times as one cycle.

In addition, the second precooling step S11 uses a single refrigerant or a second mixed refrigerant to precool the first mixed refrigerant and the natural gas.

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

1 is a flow diagram illustrating a conventional C3 / MR process

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

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

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

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

6 is a natural gas liquefaction method according to the present invention

Hereinafter, the technical spirit of the present invention will be described in more detail with reference to the accompanying drawings.

The accompanying drawings are only examples to illustrate the technical idea of the present invention in more detail, and thus the technical idea of the present invention is not limited to the forms of the accompanying drawings.

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 is a pre-cooling means 100, gas-liquid separation means 200, the first heat exchange means 300, the second heat exchange means ( 400, the first expansion means 510, the second expansion means 520, the first mixed refrigerant conversion means 600, the precooling refrigerant supply means 700, the natural gas supply means 800, and the mixing means 900. It is configured to include.

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 pipes, which will be described in detail as follows.

The first pipe is sequentially connected to the natural gas supply means 800, precooling means 100, the first heat exchange means 300, the second heat exchange means 400, the pre-cooling means 100, the first heat exchange means ( 300 and the second heat exchange means 400 are respectively connected through.

The second pipe is a cycle type and connects the precooling supply means 700 and the precooling means 100.

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

The fourth pipe is sequentially gas-liquid separation means 200, the first heat exchange means 300, the first expansion means 510, the mixing means 900, again the first heat exchange means 300, the first mixed refrigerant conversion means Connect the 600, but is connected through the first heat exchange means 300 twice.

In particular, in the fourth pipe connecting the gas-liquid separation means 200, the first heat exchange means 300, and the first expansion means, the pipe is the central portion of the first heat exchange means 300 from the gas-liquid separation means 200. Continued to and exited below or above the first heat exchange means 300 is connected to the first expansion means (510).

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

The fifth pipe is sequentially a gas-liquid separation means 200, the first heat exchange means 300, the second heat exchange means 400, the second expansion means 520, again the second heat exchange means 400, mixing means 900 ) Is connected, but is connected through the first heat exchange means 300 and through the second heat exchange means 400 twice.

Next, the components of the natural gas liquefaction system according to Embodiment 1 of the present invention will be described in detail as follows.

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

The first MR compressor 610 is composed of a three-stage compressor to compress the first mixed refrigerant.

The first MR cooler 620 introduces and cools the first mixed refrigerant compressed by the first MR compressor 610 to supply the precooling means 100.

That is, the first mixed refrigerant conversion means 600 is configured to compress and cool the first mixed refrigerant to supply the precooling means 100.

The precooling supply means 700 is configured to include a C3 compressor 710, a C3 cooler 720, C3 expansion valve 730.

In addition, the pre-cooling refrigerant supply means 700 is supplied to the pre-cooling means 100 by sequentially compressing, cooling, and expanding a single refrigerant by using the C3 compressor 710, the C3 cooler 720, and the C3 expansion valve 730. do.

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

The natural gas supply means 800 is a tank in which natural gas is stored, and supplies the stored natural gas to the precooling means 100.

The precooling means 100 independently introduces the first mixed refrigerant from the first mixed refrigerant conversion means 600, the single refrigerant from the precooling refrigerant supply means 700, and the natural gas from the natural gas supply means 800, respectively. .

In addition, the precooling means 100 precools the first mixed refrigerant and natural gas using a single refrigerant.

The gas-liquid separation means 200 introduces a first mixed refrigerant from the precooling means 100 and separates the first liquid refrigerant into the liquid phase and the second gas refrigerant into the gas phase.

The first heat exchange means 300 is composed of one first heat exchanger 310, and independently introduces natural gas from the precooling means 100, and separates the first separation refrigerant and the second separation from the gas-liquid separation means 200. Refrigerant is introduced independently, and the natural gas and the first and second separated refrigerants are cooled by using the mixed refrigerant introduced into the first heat exchange means 300 through various post-processes, but the first separated refrigerant Is cooled to less than natural gas and the second separation refrigerant to form a high temperature.

Here, the mixed refrigerant will be described below.

The first expansion means 510 is an expansion valve disposed below or above the first heat exchanger 310. The first expansion means 510 is connected to the central portion of the first heat exchanger 310 by a fourth pipe and is connected to the first heat exchanger 310. The first separated refrigerant is forcibly introduced from the tube 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 exchange means 400 is composed of one third heat exchanger 410, and independently introduces the second separated refrigerant and natural gas from the first heat exchanger 310, and then passes through the various post-processes. By using the second expansion refrigerant introduced into the second heat exchange means 400, the natural gas and the second separated refrigerant is cooled, but the second separated refrigerant is cooled less than the natural gas to form a high temperature, the natural gas is supercooled to liquefy Form natural gas.

Here, the second expanded refrigerant will be described below.

The second expansion means 520 is an expansion valve, which introduces and expands a second separation refrigerant from the third heat exchanger 410 to form a second expansion refrigerant to the third heat exchanger 410. Supply.

The mixing means 900 mixes the first expansion refrigerant introduced from the first expansion means 510 and the second expansion refrigerant introduced from the third heat exchanger 410 into the first refrigerant. To supply.

Accordingly, the present invention reduces the difference in the final discharge temperature of the mixed refrigerant introduced from the mixing means 900 to the first heat exchange means 300 and the natural gas cooled in the first heat exchange means 300 and the second separated refrigerant. Accordingly, the heat exchange efficiency is increased to reduce the energy consumption for liquefying natural gas.

Meanwhile, the first mixed refrigerant converting means 600 sequentially compresses and cools the mixed refrigerant introduced from the first heat exchanger 310 and supplies it back to the precooling means 100.

That is, the first mixed refrigerant converting means 600 converts the mixed refrigerant into the first mixed refrigerant and supplies the mixed refrigerant to the precooling 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.

Table 1 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

TABLE 2 Pressure (Bar) 53 Temperature (° C) 45 Flow Rate (kmol / hr) 35065

Natural gas is composed of the composition shown in Table 1, has a pressure and temperature shown in Table 2, and sequentially preheating means 100, the first heat exchange means 300, the second heat exchange means 400 Pass through.

Single refrigerant (propane) is compressed in four stages by the C3 compressor 710 of the pre-cooling supply means 700 has a pressure of 16.4bar, and is sequentially expanded to four stages by the C3 expander 730 7.5bar Will have a pressure of 4.2bar, 2.5bar, 1.114bar, is supplied to the precooling means (100).

TABLE 3 mole fraction (-) N2 0.0827 C1 0.4555 C2 0.3062 C3 0.1555

The first mixed refrigerant is composed of the composition shown in Table 3, and is compressed in three stages by the first MR compressor 610 of the first mixed refrigerant supply means 600 to have a pressure of 60 bar, and precooling means ( After pre-cooling through 100), the first liquid separation liquid and the second liquid separation liquid are separated through the gas-liquid separator 200.

The first separated refrigerant is introduced into the first expansion means 510 through the first heat exchange means 300 and expanded to form a first expansion 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 expansion refrigerant, and then introduced into the mixer 900 via the second heat exchange means 400 again. do.

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

Meanwhile, the first separated refrigerant, the second separated 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 between the first separated refrigerant, the second separated refrigerant, and the natural gas introduced into the first heat exchange means 300 and the mixed refrigerant introduced back into the first heat exchange means 300 through various processes. Was 4K, and the electric power consumed to liquefy natural gas was 203900KW when the temperature difference was maintained.

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

Applicant has derived empirically and experimentally the 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 configured in the same manner as the natural gas liquefaction system 1000a according to the first embodiment of the present invention. Four pipes, the fifth pipe, the first heat exchange means 300 and the second heat exchange means 400 is configured differently.

The first heat exchange means 300 includes a first heat exchanger 310 and a second heat exchanger 320, and the second heat exchange means 400 includes a third heat exchanger 410 and a fourth heat exchanger ( 420).

The first pipe is a natural gas supply means 800, pre-cooling means 100, the first heat exchanger 310, the second heat exchanger 320, the third heat exchanger 410, the fourth heat exchanger 420 ) 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 pipe is sequentially a gas-liquid separation means 200, the first heat exchanger 310, the first expansion means 510, the mixing means 900, the second heat exchanger 320, the first heat exchanger 310 The first mixed refrigerant converting means 600 is connected to the second heat exchanger 320, and the second heat exchanger 320 is connected to the first heat exchanger 310 twice.

The fifth pipe is sequentially a gas-liquid separation 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 ( 420, again connecting the third heat exchanger 410, the mixing means 900, the first heat exchanger 310, the second heat exchanger 320, and the fourth heat exchanger 420 are respectively connected through; The third heat exchanger 410 is connected through two times.

In the natural gas liquefaction system 1000b according to the second embodiment of the present invention, since the first heat exchange means 300 includes a first heat exchanger 310 and a second heat exchanger 320, Embodiment 1 of the present invention According to the configuration of the first heat exchange means 300 can be obtained.

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

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

As shown in Figure 4, the natural gas liquefaction system 1000c according to the third embodiment of the present invention is configured in the same manner as the natural gas liquefaction system 1000a according to the first embodiment of the present invention, the pre-cooling refrigerant supply means ( 700 is configured differently.

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

That is, the precooling coolant supply means 700 supplies the second mixed refrigerant to the precooling means 100 by 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.

As shown in FIG. 5, the natural gas liquefaction system 1000d according to the fourth embodiment of the present invention is configured in the same manner as the natural gas liquefaction system 1000b according to the second embodiment of the present invention. It is configured in the same manner as the precooling refrigerant supply means according to the third embodiment of the present invention.

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

As shown in FIG. 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), and a first expansion refrigerant forming step ( S04), the second introduction step (S05), the second expansion refrigerant forming step (S06), the subcooling step (S07), the mix refrigerant forming step (S08), the cooling step (S09), the conversion step (S10), the second precooling It comprises a step (S11), iteration cycle step (S12).

Referring to Figure 6 in detail with respect to the natural gas liquefaction method according to the present invention.

First, the first mixed refrigerant and the natural gas supplied from the outside are precooled using a single refrigerant or a second mixed refrigerant. This corresponds to the first precooling step S01 shown in FIG. 6.

Next, the precooled first mixed refrigerant is separated into a first separation refrigerant in a liquid phase and a second separation refrigerant in a gas phase, 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. 6. Meanwhile, the natural gas, the first separated refrigerant, and the second separated refrigerant introduced into the first heat exchange zone are cooled by the mixed refrigerant, which will be described below.

Next, the first separated refrigerant is introduced into the first expanded region and expanded to form the first expanded refrigerant. This corresponds to the first expansion refrigerant forming step S04 shown in FIG. 6.

Next, 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. 6.

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

Next, the second expansion refrigerant is supplied to the second heat exchange zone to cool the natural gas and the second separation refrigerant introduced into the second heat exchange zone in the second introduction step (S06), and the second separation refrigerant is converted into natural gas. It is cooled less to form a high temperature, and the natural gas is subcooled to form liquefied natural gas. This corresponds to the subcooling step (S07) shown in FIG.

Next, a mixed refrigerant is formed by mixing the second expanded refrigerant used in the subcooling step (S07) and the first expanded refrigerant formed in the first expanded refrigerant forming step (S04). This corresponds to the mix 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 separation refrigerant, and the second separation refrigerant introduced into the first heat exchange zone in the first introduction step (S03). The separated refrigerant is cooled less than the natural gas and the second separated refrigerant to form a high temperature first separated refrigerant. This corresponds to the cooling step (S09) shown in FIG.

Next, the mixed refrigerant introduced into the first heat exchange zone is introduced into the conversion zone, 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 is precooled. This corresponds to the second precooling step S11 shown in FIG. 6.

Next, the first mixed refrigerant separation step S02 to the second precooling step S11 are repeated one or more times in one cycle. This corresponds to the repeat cycle step S12 shown in FIG.

The present invention is not limited to the above-described embodiments, and the scope of application is not limited, and various modifications can be made without departing from the gist of the present invention as claimed in the claims.

(Explanation of the sign)

1000a, b, c, d: natural gas liquefaction system according to the present invention

 100: precooling means

 200: gas-liquid separation means

 300: first heat exchange means

 310: first heat exchanger 320: second heat exchanger

 400: second heat exchange means

 410: third heat exchanger 420: fourth heat exchanger

 510: first expansion means 520: second expansion means

 600: first mixed refrigerant conversion means

 700: precooling supply means

 800: natural gas supply means

 900: mixing means

Claims (11)

Precooling means (100); Gas-liquid separation means 200 connected to the precooling means 100; First heat exchange means (300) connected to the precooling means (100) and the gas-liquid separation means (200), respectively; Second heat exchange means (400) connected to the first heat exchange means (300); First expansion means (510) having one end connected to the first heat exchange means (300); Second expansion means 520 having both ends connected to the second heat exchange means 400; First mixed refrigerant conversion means (600) connected to the precooling means (100) and the first heat exchange means (300), respectively; Precooling supply means (700) connected to the precooling means (100); Natural gas supply means (800) connected to the precooling means (100); And And a 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 method of claim 1, The first heat exchange means 300 is A first heat exchanger 310 connected to the precooling means 100 and the gas-liquid separation means 200, The second heat exchange means 400 Natural gas liquefaction system is a third heat exchanger (410) connected to the first heat exchanger (310). The method of claim 1, The first heat exchange means 300 is A first heat exchanger 310 connected to the precooling means 100 and the gas-liquid separation means 200, and a second heat exchanger 320 connected to the first heat exchanger 310, The second heat exchange means 400 Natural gas liquefaction system is 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). The method of claim 3, The first expansion means 510 is 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 is One end is connected to the third heat exchanger (410) and the other end is connected to the fourth heat exchanger (420) natural gas liquefaction system. The method of claim 1, The first mixed refrigerant conversion means 600 Supplying a first mixed refrigerant to the precooling means (100), The precooling supply means 700 is Supply a precooling refrigerant to the precooling means (100), The natural gas supply means 800 Supply natural gas to the precooling means 100, The precooling means 100 Precooling the first mixed refrigerant and the natural gas supplied from the precooling means 100 and the natural gas supply means 800 by using the precooling refrigerant supplied from the first mixed refrigerant converting means 600 , The gas-liquid separation means 200 The first mixed refrigerant introduced from the precooling means 100 is separated into a first separated refrigerant in the liquid phase and a second separated refrigerant in the gas phase, The first heat exchange means 300 is The natural gas, the first separated refrigerant and the second separated refrigerant are introduced from the precooling means 100, and the mixed gas is used to cool the natural gas, the first separated refrigerant, and the second separated refrigerant. By cooling the first separated refrigerant less than the natural gas and the second separated refrigerant to form a high temperature, The first expansion means 510 is Expanding the first separated refrigerant introduced from the first heat exchange means 300 to form a 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 by using a second expansion refrigerant, and the second separated refrigerant is Less cooling than natural gas to form a high temperature, supercooling the natural gas to form liquefied natural gas, The second expansion means 520 is Supplying the second expanded refrigerant formed by expanding the second separated refrigerant introduced from the second heat exchange means 400 to the second heat exchange means 400, The mixing means 900 is The first heat exchange means 300 includes the mixed refrigerant formed by mixing a portion of the first expansion refrigerant introduced from the first expansion means 510 and the second expansion refrigerant introduced from the second heat exchange means 400. ) Natural gas liquefaction system. The method of claim 5, wherein the precooling refrigerant Natural gas liquefaction system that is a single refrigerant or a second mixed refrigerant. The method of claim 5, wherein the first mixed refrigerant conversion means 600 A natural gas liquefaction system for compressing and cooling the mixed refrigerant introduced from the first heat exchange means (300) sequentially to a first mixed refrigerant, and supplying the first mixed refrigerant to the precooling means (100). A first precooling step (S01) of precooling the first mixed refrigerant and natural gas; A first mixed refrigerant separation step (S02) for separating the first mixed refrigerant into a liquid first separation refrigerant and a gaseous second separation refrigerant, respectively; A first introduction step (S03) of introducing the natural gas, the first separated refrigerant, and the second separated refrigerant into the first heat exchange zone without mixing; A first expansion refrigerant forming step (S04) of introducing the first separation refrigerant into a first expansion region and expanding the first separation refrigerant to form the first expansion refrigerant; A second introduction step (S05) of introducing the natural gas and the second separated refrigerant into a second heat exchange zone without mixing; A second expanded refrigerant forming step (S06) of introducing the second separated refrigerant into a second expanded region and expanding the same to form a second expanded refrigerant; And Supplying the second expanded refrigerant to the second heat exchange zone to cool the natural gas and the second separated refrigerant introduced into the second heat exchange zone, but cooling the second separated refrigerant less than the natural gas. Forming a high temperature and subcooling the natural gas to form a liquefied natural gas (S07); A mix refrigerant forming step (S08) of mixing the second expanded refrigerant and the first expanded refrigerant to form a mixed refrigerant; Supplying the mixed refrigerant 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, wherein the first separated refrigerant is Natural gas and a cooling method (S09) to cool less than the second separated refrigerant to form a high temperature; natural gas liquefaction method comprising a. The method of claim 8, wherein the first pre-cooling step (S01) A natural gas liquefaction method using a single refrigerant or a second mixed refrigerant to precool the first mixed refrigerant and the natural gas. The method of claim 8, wherein the natural gas liquefaction method A conversion step of converting the mixed refrigerant into a first mixed refrigerant by sequentially compressing and cooling (S10); And A second precooling step (S11) of precooling the first mixed refrigerant and the natural gas; The first mixed refrigerant separation step (S02) to the second pre-cooling step (S11) in one cycle iterative cycle step (S12) for repeating one or more times; natural gas liquefaction method further comprising. The method of claim 10, wherein the second pre-cooling step (S11) A natural gas liquefaction method using a single refrigerant or a second mixed refrigerant to precool the first mixed refrigerant and the natural gas.

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