Natural gas liquefaction equipment

Abstract

The utility model discloses natural gas liquefaction equipment. The natural gas liquefaction equipment comprises a feed gas supply source, a heavy hydrocarbon removal tower, a cold box, a shunting device, an LNG (Liquefied Natural Gas) collecting device, a heavy hydrocarbon collecting device, a fourth pipeline and a fifth pipeline, the heavy hydrocarbon removal tower is provided with a liquid phase outlet, a first feeding hole, a second feeding hole, a third feeding hole and a gas phase outlet which are sequentially distributed at intervals in the direction from the bottom to the top of the heavy hydrocarbon removal tower; one end of the fourth pipeline is communicated with the gas phase outlet, the other end of the fourth pipeline is communicated with the second heat exchange flow channel of the cold box, the fifth pipeline is communicated with the fourth pipeline through the second heat exchange flow channel, the end, away from the second heat exchange flow channel, of the fifth pipeline is communicated with the LNG collecting device, and the fifth pipeline is communicated with the third feeding port through the flow dividing device. According to the scheme, the problem that the washing effect of natural gas liquefaction equipment on natural gas with the small heavy hydrocarbon content is poor can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of natural gas purification, in particular to natural gas liquefaction equipment. Background Art

[0002] During the natural gas liquefaction process, the raw gas composition is relatively complex and the heavy hydrocarbon content varies greatly. Therefore, in a low-temperature environment, the heavy hydrocarbon content in the cold box will increase. If the heavy hydrocarbons are not removed in time, it is easy to cause blockage of the cold box and pipelines. Therefore, the heavy hydrocarbons need to be separated and removed before or during the condensation process of natural gas.

[0003] In the related art, natural gas liquefaction equipment generally uses an absorption method to remove heavy hydrocarbons from natural gas. Specifically, the heavy hydrocarbons condensed from the raw gas itself are used as a scrubbing liquid to scrub the heavy hydrocarbons in the raw gas.

[0004] However, this method of removing heavy hydrocarbons is suitable for feed gas with a high heavy hydrocarbon content. When the feed gas contains a low amount of heavy hydrocarbons, the resulting scrubbing liquid flow rate is low, resulting in unsatisfactory scrubbing results. Therefore, the natural gas liquefaction equipment in the related art has a poor scrubbing effect on natural gas with a low heavy hydrocarbon content. Utility Model Content

[0005] The utility model discloses a natural gas liquefaction device, which solves the problem that the natural gas liquefaction device has a poor washing effect on natural gas with a small heavy hydrocarbon content.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions:

[0007] A natural gas liquefaction device includes a raw gas supply source, a heavy hydrocarbon removal tower, a cold box, a diverter, an LNG collection device, a heavy hydrocarbon collection device, a first pipeline, a second pipeline, a third pipeline, a fourth pipeline, and a fifth pipeline;

[0008] The heavy hydrocarbon removal tower has a liquid phase outlet, a first feed port, a second feed port, a third feed port, and a gas phase outlet spaced in sequence from the bottom to the top thereof; one end of the first pipeline is connected to the raw gas supply source, and the other end of the first pipeline is connected to the first feed port; one end of the second pipeline is connected to the raw gas supply source, and the other end of the second pipeline is connected to the first heat exchange flow channel of the cold box; the third pipeline is connected to the second pipeline through the first heat exchange flow channel, and the end of the third pipeline facing away from the first heat exchange flow channel is connected to the second feed port;

[0009] One end of the fourth pipeline is connected to the gas phase outlet, the other end of the fourth pipeline is connected to the second heat exchange channel of the cold box, the fifth pipeline is connected to the fourth pipeline through the second heat exchange channel, the end of the fifth pipeline facing away from the second heat exchange channel is connected to the LNG collection device, the fifth pipeline is connected to the third feed port through the diverter device, and the heavy hydrocarbon collection device is connected to the liquid phase outlet.

[0010] The technical solution adopted by the utility model can achieve the following beneficial effects:

[0011] In the natural gas liquefaction equipment disclosed in the present utility model, the natural gas from which heavy hydrocarbons have been removed enters the second heat exchange flow channel of the cold box through the fourth pipeline for cooling and liquefaction, and the liquefied natural gas enters the LNG collection device through the fifth pipeline for collection. At this time, the fifth pipeline is connected to the third feed port of the heavy hydrocarbon removal tower through a diverter device. The diverter device introduces part of the liquefied natural gas into the heavy hydrocarbon removal tower through the diverter device, thereby using the liquefied natural gas as a washing liquid to wash the raw gas. In the scheme disclosed in the present application, the use of liquefied natural gas as a washing liquid can ensure that the flow rate of the washing liquid is sufficient, so the natural gas liquefaction equipment disclosed in the present application has a better washing effect on natural gas with a lower heavy hydrocarbon content. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0013] Figure 1 This is a schematic structural diagram of the natural gas liquefaction equipment disclosed in an embodiment of the present utility model;

[0014] Figure 2 This is a structural diagram of the liquefaction process of the natural gas liquefaction equipment disclosed in an embodiment of the present utility model;

[0015] Figure 3 This is a structural schematic diagram of the cooling process of the natural gas liquefaction equipment disclosed in an embodiment of the present utility model.

[0016] Description of reference numerals:

[0017] 100-raw gas supply source,

[0018] 200-heavy hydrocarbon removal tower, 210-liquid phase outlet, 220-first feed port, 230-second feed port, 240-third feed port, 250-gas phase outlet,

[0019] 300-cold box, 310-first heat exchange channel, 320-second heat exchange channel, 330-third heat exchange channel, 340-fourth heat exchange channel, 350-fifth heat exchange channel, 360-sixth heat exchange channel,

[0020] 410-diversion device, 411-LNG buffer tank, 412-sixth pipeline, 413-seventh pipeline, 414-boosting pump, 415-first throttling expansion valve, 420-heavy hydrocarbon collection device, 430-LNG collection device,

[0021] 510-first pipeline, 520-second pipeline, 530-third pipeline, 540-fourth pipeline, 550-fifth pipeline, 560-eighth pipeline, 570-second throttling expansion valve, 580-third throttling expansion valve, 590-fourth throttling expansion valve,

[0022] 600 - hybrid refrigeration device, 610 - first compressor, 620 - second compressor, 630 - first separator, 640 - second separator. DETAILED DESCRIPTION

[0023] To make the purpose, technical solutions, and advantages of the present invention more clear, the following will provide a clear and complete description of the technical solutions of the present invention in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0024] The technical solutions disclosed in various embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] like Figures 1 to 3 As shown, an embodiment of the present invention discloses a natural gas liquefaction facility for removing heavy hydrocarbons from dried natural gas and then liquefying it to produce LNG (liquefied natural gas). The disclosed natural gas liquefaction facility includes a raw gas supply source 100, a heavy hydrocarbon removal tower 200, a cold box 300, a flow splitter 410, an LNG collection device 430, a heavy hydrocarbon collection device 420, a first pipeline 510, a second pipeline 520, a third pipeline 530, a fourth pipeline 540, and a fifth pipeline 550.

[0026] The raw gas supply source 100 is used to provide raw gas, where the raw gas refers to dry natural gas. The raw gas contains heavy hydrocarbons, so before the raw gas is liquefied, the heavy hydrocarbon components in the raw gas need to be removed.

[0027] Heavy hydrocarbon removal tower 200 is used to remove heavy hydrocarbon components from the feed gas. Cold box 300 provides refrigeration for the natural gas liquefaction equipment. Diverter 410 is used to divert LNG. LNG collection unit 430 is used to store and collect liquefied LNG. Heavy hydrocarbon collection unit 420 is used to store and collect the removed heavy hydrocarbons.

[0028] The heavy hydrocarbon removal tower 200 has a liquid phase outlet 210, a first feed port 220, a second feed port 230, a third feed port 240, and a gas phase outlet 250, which are spaced apart in sequence from the bottom to the top. Specifically, the liquid phase outlet 210 is located at the bottom of the heavy hydrocarbon removal tower 200, and the heavy hydrocarbon collection device 420 is connected to the liquid phase outlet 210. At this time, the removed heavy hydrocarbons are discharged into the heavy hydrocarbon collection device 420 through the liquid phase outlet 210. The gas after the heavy hydrocarbons are removed is discharged from the gas phase outlet 250. The first feed port 220, the second feed port 230, and the third feed port 230 are used to introduce raw gas and washing liquid. The first feed port 220 is located between the liquid phase outlet 210 and the second feed port 230. At this time, the first feed port 220 is set close to the bottom of the heavy hydrocarbon removal tower 200. The third feed port 240 is located between the gas phase outlet 250 and the second feed port 230. At this time, the third feed port 240 is set close to the top of the heavy hydrocarbon removal tower 200. At this time, the second feed port 230 is located between the first feed port 220 and the third feed port 240, so the second feed port 230 is located in the middle of the heavy hydrocarbon removal tower 200.

[0029] One end of the first pipeline 510 is connected to the raw gas supply source 100, and the other end of the first pipeline 510 is connected to the first feed port 220. At this time, the first pipeline 510 passes part of the raw gas into the bottom position of the heavy hydrocarbon removal tower 200. Here, part of the raw gas from the raw gas supply source 100 directly enters the heavy hydrocarbon removal tower 200 through the first pipeline 510 without passing through the cold box 300 for heat exchange. One end of the second pipeline 520 is connected to the raw gas supply source 100, and the other end of the second pipeline 520 is connected to the first heat exchange channel 310 of the cold box 300. The third pipeline 530 is connected to the second pipeline 520 through the first heat exchange channel 310, and the end of the third pipeline 530 facing away from the first heat exchange channel 310 is connected to the second feed port 230. At this time, another part of the raw gas from the raw gas supply source 100 enters the cold box 300 through the second pipeline 520 for heat exchange, and the raw gas after heat exchange is passed into the middle position of the heavy hydrocarbon removal tower 200 through the third pipeline 530.

[0030] One end of the fourth pipeline 540 is connected to the gas phase outlet 250, and the other end of the fourth pipeline 540 is connected to the second heat exchange channel 320 of the cold box 300. The fifth pipeline 550 is connected to the fourth pipeline 540 through the second heat exchange channel 320. The end of the fifth pipeline 550 facing away from the second heat exchange channel 320 is connected to the LNG collection device 430. The fifth pipeline 550 is connected to the third feed inlet 240 through the diverter 410. At this time, the gas phase, after the heavy hydrocarbons have been removed, enters the cold box 300 through the fourth pipeline 540 for heat exchange to form liquefied natural gas, which is then passed to the LNG collection device 430 through the fifth pipeline 550. The diverter 410 introduces a portion of the liquefied natural gas from the fifth pipeline 550 into the heavy hydrocarbon removal tower 200 for use as a scrubbing liquid.

[0031] The specific natural gas liquefaction process is that the raw gas includes a first part and a second part, and the flow rate of the first part is greater than the flow rate of the second part. The first part is heat-exchanged to a first preset temperature by the cold box 300 and then led out of the middle position of the heavy hydrocarbon removal tower 200. At this time, the raw gas introduced from the middle position of the heavy hydrocarbon removal tower 200 passes through the heavy hydrocarbon removal tower 200 from bottom to top, and then is washed by the LNG introduced from the third feed port 240 of the heavy hydrocarbon removal tower 200. At this time, the heavy hydrocarbon components in the first part are washed and removed. The removed heavy hydrocarbon components settle downward, and then the second part heats the removed heavy hydrocarbon components, thereby further separating the light components in the low-temperature heavy hydrocarbons, such as methane. Then, heavy hydrocarbons at room temperature are obtained at the bottom of the heavy hydrocarbon removal tower 200. After the gas phase coming out of the gas phase outlet 250 at the top of the heavy hydrocarbon removal tower 200 is further deep-cooled in the gas recooling box 300, most of the product LNG is sent to the off-site LNG collection device 430 for collection; a small part of the LNG is introduced into the heavy hydrocarbon removal tower 200 by the diversion device 410 as a washing liquid for removing heavy hydrocarbons to wash the raw gas.

[0032] In the embodiment disclosed herein, fifth pipeline 550 is connected to third feed port 240 of heavy hydrocarbon removal tower 200 via diverter 410. Diverter 410 directs a portion of the liquefied natural gas through diverter 410 into heavy hydrocarbon removal tower 200, thereby using the liquefied natural gas as a scrubbing liquid to scrub the feed gas. Using liquefied natural gas as the scrubbing liquid ensures a sufficient flow rate of the scrubbing liquid, resulting in the disclosed natural gas liquefaction equipment achieving a superior scrubbing effect on natural gas with a low heavy hydrocarbon content.

[0033] Furthermore, the natural gas liquefaction equipment disclosed herein divides the feed gas into two parts. One part, after pre-cooling and heat exchange, enters the middle portion of heavy hydrocarbon removal tower 200, where it undergoes scrubbing and removal with LNG. The other part is directly fed to the bottom of heavy hydrocarbon removal tower 200. This part, without undergoing heat exchange and therefore at a higher temperature, evaporates and separates the light hydrocarbons from the removed heavy hydrocarbons. Therefore, the natural gas liquefaction equipment disclosed herein can recover and liquefy the light hydrocarbons, thereby improving the liquefaction rate of natural gas.

[0034] In the above embodiment, the first portion is heat exchanged to 55°C by the cold box 300 and then enters the heavy hydrocarbon removal tower 200. The gas phase exiting the top of the heavy hydrocarbon removal tower 200 may have a temperature of -69°C. After further deep cooling to -162°C in the cold box 300, it is liquefied and then passed into the LNG collection device 430. Of course, the temperatures of the various components in this application can also be other values, which are not limited herein. The operating pressure of the heavy hydrocarbon removal tower 200 disclosed in this application can be 4.8 MPaG, the tower bottom temperature can be 3°C, and the tower top temperature can be -69°C.

[0035] In the above solution, the fifth pipeline 550 and the third feed port 240 can be directly connected by a pipeline, thereby achieving communication between the fifth pipeline 550 and the third feed port 240, so the diverter device 410 can be a pipeline.

[0036] In another optional solution, the diverter device 410 may include an LNG buffer tank 411, a sixth pipeline 412, and a seventh pipeline 413. One end of the sixth pipeline 412 may be connected to the fifth pipeline 550, and the other end of the sixth pipeline 412 may be connected to the feed port of the LNG buffer tank 411. One end of the seventh pipeline 413 is connected to the discharge port of the LNG buffer tank 411, and the other end of the seventh pipeline 413 is connected to the third feed port 240. In this case, the sixth pipeline 412 introduces the LNG in the fifth pipeline 550 into the LNG buffer tank 411 for buffering, and then passes it into the heavy hydrocarbon removal tower 200 via the seventh pipeline 413.

[0037] In this scheme, LNG first enters the LNG buffer tank 411 for buffering, and then passes into the heavy hydrocarbon removal tower 200. At this time, the flow rate and pressure of LNG are relatively stable, so it is more conducive to improving the stability of LNG during introduction, and it is not easy to cause excessive pressure difference changes in the heavy hydrocarbon removal tower 200.

[0038] In the above solution, when the pressure within the LNG buffer tank 411 is lower than the pressure within the heavy hydrocarbon removal tower 200, diversion is likely to occur. Therefore, in another alternative solution, the diversion device 410 further includes a booster pump 414, which is installed on the seventh pipeline 413. In this solution, the booster pump 414 can boost the LNG, thereby ensuring a higher delivery pressure and positive delivery, making diversion less likely to occur.

[0039] Optionally, the specific structure and principle of the boost pump 414 are common knowledge and are not limited herein.

[0040] In another optional embodiment, the diverter device 410 may further include a first throttling expansion valve 415, which may be disposed in the seventh pipeline 413 and located between the booster pump 414 and the third feed port 240. In this case, the LNG first needs to pass through the first throttling expansion valve 415 for throttling and pressure reduction before passing through the third feed port 240, and then enter the heavy hydrocarbon removal tower 200 through the third feed port 240. In this solution, the LNG is decompressed after passing through the first throttling expansion valve 415, thereby reducing its pressure, thereby facilitating the entry of the LNG into the heavy hydrocarbon removal tower 200, ensuring the stability of the pressure in the heavy hydrocarbon removal tower 200, and thus avoiding a large number of pressure fluctuations.

[0041] In the above solution, the natural gas liquefaction equipment may further include a hybrid refrigeration device 600, which may be connected to the cold box 300 and used to provide cooling for the cold box 300. Specifically, both the liquid-phase refrigerant outlet and the gas-phase refrigerant outlet of the hybrid refrigeration device 600 may be connected to corresponding heat exchange channels in the cold box 300, thereby providing cooling for the cold box 300. The refrigerant in the hybrid refrigeration device 600 is typically a combination of methane, nitrogen, ethylene, propane, isobutane, and isopentane.

[0042] In an optional solution, the natural gas liquefaction equipment may further include an eighth pipeline 560, one end of which may be connected to the fourth pipeline 540, and the other end of which may be connected to the refrigerant feed port of the hybrid refrigeration device 600. In this case, the eighth pipeline 560 can introduce a portion of the gas phase after the heavy hydrocarbons are removed into the refrigerant feed port of the hybrid refrigeration device 600, so that the gas phase after the heavy hydrocarbons are removed can be fed into the hybrid refrigeration device 600 as refrigerant.

[0043] In this solution, the gas phase after partial removal of heavy hydrocarbons can be fed into the hybrid refrigeration device 600 as a refrigerant, thereby realizing the internal circulation of the natural gas liquefaction equipment, reducing the refrigerant feeding operation, and further optimizing the natural gas liquefaction equipment.

[0044] Furthermore, the natural gas liquefaction equipment may further include a second throttling expansion valve 570, which may be provided on the eighth pipeline 560. This solution can prevent the hybrid refrigeration device 600 from generating large pressure fluctuations, thereby improving the safety of the hybrid refrigeration device 600.

[0045] In the above solution, the gas phase after heavy hydrocarbon removal, the gas phase refrigerant generated by the mixed refrigeration device 600 and the liquid phase refrigerant are introduced into the corresponding heat exchange flow channels and enter the refrigerant feed port of the mixed refrigeration device 600.

[0046] In another optional embodiment, the gas-phase refrigerant outlet of the hybrid refrigeration device 600 and the liquid-phase refrigerant outlet of the hybrid refrigeration device 600 are converged in the third heat exchange channel 330 of the cold box 300 after heat exchange through the corresponding heat exchange channels of the cold box 300. The third heat exchange channel 330 is connected to the refrigerant feed port of the hybrid refrigeration device 600, and the eighth pipeline 560 is connected to the third heat exchange channel 330. In this case, the gas phase after heavy hydrocarbon removal, the gas-phase refrigerant generated by the hybrid refrigeration device 600, and the liquid-phase refrigerant are converged in the same heat exchange channel and then enter the refrigerant feed port through the same heat exchange channel and the same pipeline.

[0047] In this solution, the gas phase after heavy hydrocarbon removal, the gas phase refrigerant produced by the mixed refrigeration device 600, and the liquid phase refrigerant all use the same heat exchange flow channel when they reflux, which is beneficial to simplify the connection structure with the cold box 300 and further simplify the structure of the natural gas liquefaction equipment.

[0048] In one alternative, the hybrid refrigeration device 600 includes a compressor and a separator, which are connected to each other. In this case, the refrigerant enters the separator to separate the gas phase and the liquid phase. The gas phase passes through the cold box 300, enters the throttling expansion valve, is throttled, and then returns to the compressor. The liquid phase enters the cold box 300, enters the throttling expansion valve, is throttled, and then returns to the compressor. In this case, the hybrid refrigerant device employs a two-stage throttling method.

[0049] In another optional embodiment, the hybrid refrigeration device 600 may include a first compressor 610, a second compressor 620, a first separator 630, and a second separator 640. The first compressor 610 is connected to the third heat exchange channel 330, and the refrigerant feed port is provided on the first compressor 610. The first compressor 610 is connected to the second compressor 620 and the first separator 630. The gas-phase refrigerant outlet of the first separator 630 is connected to the second compressor 620, and the liquid-phase refrigerant outlet of the first separator 630 is connected to the fourth heat exchange channel 340 of the cold box 300, which is in turn connected to the third heat exchange channel 330. The second compressor 620 is connected to the second separator 640, and the liquid-phase refrigerant outlet of the second separator 640 is connected to the fifth heat exchange channel 350 of the cold box 300, which is in turn connected to the third heat exchange channel 330. The gas-phase refrigerant outlet of the second separator 640 is connected to the sixth heat exchange channel 360 of the cold box 300 , and the sixth heat exchange channel 360 is connected to the third heat exchange channel 330 .

[0050] During the specific operation, part of the refrigerant in the first compressor 610 enters the first separator 630, while another part enters the second compressor 620 for pressurization. The gaseous refrigerant separated in the first separator 630 enters the second compressor 620. Both parts of the refrigerant are pressurized to 4.3 MPaG in the second compressor 620, cooled, and then enter the second separator 640. At this time, the liquid refrigerant separated in the first separator 630 enters the cold box 300 for heat exchange, is depressurized, enters the cold box 300 for reheating, and then returns to the first compressor 610. The liquid refrigerant and gaseous refrigerant separated in the second separator 640 separately enter the cold box 300 for heat exchange, are depressurized, return to the cold box 300 for reheating, and then return to the first compressor 610.

[0051] This solution can achieve three-stage throttling cooling, namely the liquid refrigerant separated by the first separator 630, the gas refrigerant separated by the second separator 640, and the liquid refrigerant. These three stages of throttling can provide cooling capacity for the cold box 300, thereby making full use of the refrigerant and reducing the energy consumption of the natural gas liquefaction equipment.

[0052] In another optional embodiment, the natural gas liquefaction equipment may further include a third throttling expansion valve 580. The third throttling expansion valve 580 may be disposed in the fifth pipeline 550 and located between the connection point between the fifth pipeline 550 and the LNG collection device 430 and the connection point between the fifth pipeline 550 and the diverter device 410. In this case, the LNG is depressurized before entering the LNG collection device 430, thereby ensuring a stable pressure.

[0053] Optionally, the LNG is throttled and depressurized to 0.2 MPaG by the third throttling expansion valve 580 , and then sent to the LNG collection device 430 for storage and collection.

[0054] In another solution, the natural gas liquefaction equipment may further include a fourth throttling expansion valve 590, which may be disposed on the first pipeline 510. This solution can further improve the stability of the equipment pressure.

[0055] In the above solution, the communication pipeline between the heavy hydrocarbon collection device 420 and the liquid phase outlet 210 may also be provided with a throttling expansion valve to ensure the stability of the equipment pressure.

[0056] The above embodiments of the present invention focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0057] The above description is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims of the present invention.

Claims

1. A natural gas liquefaction equipment, characterized in that: The system comprises a raw gas supply source (100), a heavy hydrocarbon removal tower (200), a cold box (300), a flow dividing device (410), an LNG collecting device (430), a heavy hydrocarbon collecting device (420), a first pipeline (510), a second pipeline (520), a third pipeline (530), a fourth pipeline (540), and a fifth pipeline (550); The heavy hydrocarbon removal tower (200) has a liquid phase outlet (210), a first feed port (220), a second feed port (230), a third feed port (240) and a gas phase outlet (250) which are sequentially spaced from the bottom to the top of the tower; one end of the first pipeline (510) is connected to the raw gas supply source (100), and the other end of the first pipeline (510) is connected to the first feed port (220); one end of the second pipeline (520) is connected to the raw gas supply source (100), and the other end of the second pipeline (520) is connected to the first heat exchange channel (310) of the cold box (300); the third pipeline (530) is connected to the second pipeline (520) through the first heat exchange channel (310), and the end of the third pipeline (530) away from the first heat exchange channel (310) is connected to the second feed port (230); One end of the fourth pipeline (540) is connected to the gas phase outlet (250), the other end of the fourth pipeline (540) is connected to the second heat exchange channel (320) of the cold box (300), the fifth pipeline (550) is connected to the fourth pipeline (540) through the second heat exchange channel (320), the end of the fifth pipeline (550) away from the second heat exchange channel (320) is connected to the LNG collection device (430), the fifth pipeline (550) is connected to the third feed port (240) through the diverter device (410), and the heavy hydrocarbon collection device (420) is connected to the liquid phase outlet (210).

2. The natural gas liquefaction equipment according to claim 1, characterized in that: The diversion device (410) includes an LNG buffer tank (411), a sixth pipeline (412) and a seventh pipeline (413), one end of the sixth pipeline (412) is connected to the fifth pipeline (550), the other end of the sixth pipeline (412) is connected to the feed port of the LNG buffer tank (411), one end of the seventh pipeline (413) is connected to the discharge port of the LNG buffer tank (411), and the other end of the seventh pipeline (413) is connected to the third feed port (240).

3. The natural gas liquefaction equipment according to claim 2, characterized in that: The flow dividing device (410) further includes a booster pump (414), and the booster pump (414) is arranged on the seventh pipeline (413).

4. The natural gas liquefaction equipment according to claim 3, characterized in that: The diversion device (410) further includes a first throttling expansion valve (415), which is arranged in the seventh pipeline (413) and located between the boosting pump (414) and the third feed port (240).

5. The natural gas liquefaction equipment according to claim 1, characterized in that: The natural gas liquefaction equipment further includes a mixed refrigeration device (600) and an eighth pipeline (560). The mixed refrigeration device (600) is connected to the cold box (300). The mixed refrigeration device (600) is used to provide cooling for the cold box (300). One end of the eighth pipeline (560) is connected to the fourth pipeline (540), and the other end of the eighth pipeline (560) is connected to a refrigerant feed port of the mixed refrigeration device (600).

6. The natural gas liquefaction equipment according to claim 5, characterized in that: The natural gas liquefaction equipment further comprises a second throttling expansion valve (570), and the second throttling expansion valve (570) is arranged on the eighth pipeline (560).

7. The natural gas liquefaction equipment according to claim 6, characterized in that: The gas-phase refrigerant outlet of the mixed refrigeration device (600) and the liquid-phase refrigerant outlet of the mixed refrigeration device (600) are converged into the third heat exchange channel (330) of the cold box (300) after heat exchange through the corresponding heat exchange channel of the cold box (300), the third heat exchange channel (330) is connected to the refrigerant feed port of the mixed refrigeration device (600), and the eighth pipeline (560) is connected to the third heat exchange channel (330).

8. The natural gas liquefaction equipment according to claim 7, characterized in that: The hybrid refrigeration device (600) includes a first compressor (610), a second compressor (620), a first separator (630) and a second separator (640), wherein the first compressor (610) is connected to the third heat exchange channel (330), the first compressor (610) is connected to the second compressor (620) and the first separator (630), the gas-phase refrigerant outlet of the first separator (630) is connected to the second compressor (620), and the liquid-phase refrigerant outlet of the first separator (630) is connected to the fourth heat exchange channel (340) of the cold box (300). , the fourth heat exchange channel (340) is connected to the third heat exchange channel (330); the second compressor (620) is connected to the second separator (640), the liquid-phase refrigerant outlet of the second separator (640) is connected to the fifth heat exchange channel (350) of the cold box (300), and the fifth heat exchange channel (350) is connected to the third heat exchange channel (330); the gas-phase refrigerant outlet of the second separator (640) is connected to the sixth heat exchange channel (360) of the cold box (300), and the sixth heat exchange channel (360) is connected to the third heat exchange channel (330).

9. The natural gas liquefaction equipment according to claim 1, characterized in that: The natural gas liquefaction equipment further includes a third throttling expansion valve (580), which is arranged on the fifth pipeline (550) and located between a connection point between the fifth pipeline (550) and the LNG collecting device (430) and a connection point between the fifth pipeline (550) and the diverter device (410).

10. The natural gas liquefaction equipment according to claim 1, characterized in that: The natural gas liquefaction equipment further comprises a fourth throttling expansion valve (590), and the fourth throttling expansion valve (590) is arranged on the first pipeline (510).

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