Integrated natural gas liquefaction co-production helium extraction device and method

Abstract

The invention discloses an integrated natural gas liquefaction co-production helium extraction device and method. The device comprises an integrated methane liquefaction system, a mixed refrigerant refrigeration cycle system, an integrated methane removal system and a nitrogen refrigeration cycle system, the integrated methane liquefaction system comprises a liquefaction heat exchanger and a denitrification tower, and the liquefaction heat exchanger and the denitrification tower are connected through a pipeline; the integrated methane liquefaction system is integrated in the liquefaction cold box; the mixed refrigerant refrigeration cycle system is used for providing cooling capacity for the integrated methane liquefaction system; the integrated methane removal system comprises a demethanization heat exchanger and a helium concentration tower, and the demethanization heat exchanger and the helium concentration tower are connected through a pipeline; the integrated methane removal system is integrated in the demethanizing cold box; and the nitrogen refrigeration cycle system is used for providing cooling capacity for the integrated methane removal system. The length of an external cold insulation pipeline is reduced, cold loss is reduced, and the energy use function efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas liquefaction, and particularly to an integrated natural gas liquefaction combined production helium extraction device and method. Background Art

[0002] Helium is a monoatomic noble gas with the lowest critical temperature and the most difficult gas to liquefy (liquefaction temperature is -269 °C). As a strategic material, helium plays an important role in applications such as frontier scientific research, high-tech industries, and national defense industries. At present, helium-containing natural gas is the only source for industrial production of helium. The helium product obtained by cryogenic separation method for helium extraction has high purity and recovery rate, and it is the main method for extracting helium from natural gas. Since the cryogenic helium extraction process involves the liquefaction and separation of methane and nitrogen, the lowest cooling temperature exceeds -180 °C, and the energy consumption of a large amount of cold loss in the helium extraction process accounts for a high proportion in the production cost, resulting in low energy utilization rate. Summary of the Invention

[0003] In view of the above problems, the purpose of the present invention is to provide an integrated natural gas liquefaction combined production helium extraction device and method.

[0004] In the first aspect, an embodiment of the present invention provides an integrated natural gas liquefaction combined production helium extraction device, including:

[0005] An integrated methane liquefaction system, a mixed refrigerant refrigeration cycle system, an integrated methane removal system, and a nitrogen refrigeration cycle system;

[0006] The integrated methane liquefaction system includes a liquefaction heat exchanger and a denitrification tower, and the liquefaction heat exchanger and the denitrification tower are connected by pipelines;

[0007] The integrated methane liquefaction system is integrated in a cold box;

[0008] The mixed refrigerant refrigeration cycle system is used to provide cold energy for the integrated methane liquefaction system;

[0009] The integrated methane removal system includes a demethanation heat exchanger and a helium enrichment tower, and the demethanation heat exchanger and the helium enrichment tower are connected by pipelines;

[0010] The integrated methane removal system is integrated in a cold box;

[0011] The nitrogen refrigeration cycle system is used to provide cold energy for the integrated methane removal system.

[0012] In one embodiment, the device further includes: a heavy hydrocarbon separation tank;

[0013] The heavy hydrocarbon separation tank, the liquefaction heat exchanger, and the raw natural gas are connected in sequence;

[0014] The heavy hydrocarbon separation tank is used to receive raw natural gas and remove heavy hydrocarbons from the raw natural gas.

[0015] In one embodiment, the top of the heavy hydrocarbon separation tank includes a first outlet and a second outlet. The first outlet is connected to the bottom of the denitrification tower through a first throttle valve; the second outlet is connected to the denitrification tower through a liquefaction heat exchanger and a second throttle valve.

[0016] In one embodiment, the device further includes: a recycle gas boosting system;

[0017] The recycle gas boosting system includes a recycle gas compressor and a recycle gas compressor outlet cooler;

[0018] The recycle gas compressor and the recycle gas compressor outlet cooler are connected.

[0019] In one embodiment, the recycle gas compressor outlet cooler includes a third outlet;

[0020] The top of the denitrification tower is sequentially connected to the liquefaction heat exchanger, the recycle gas compressor, the third outlet of the recycle gas compressor outlet cooler, the liquefaction heat exchanger, and a third throttle valve through pipelines to form a circulation loop;

[0021] The bottom of the denitrification tower is connected to the liquefied natural gas storage tank area through the liquefaction heat exchanger and a fourth throttle valve to send the liquefied natural gas to the liquefied natural gas storage tank area.

[0022] In one embodiment, the helium enrichment tower includes: a tower body, a bottom reboiler of the enrichment tower, and a top condenser of the enrichment tower; the recycle gas compressor outlet cooler further includes: a fourth outlet;

[0023] The bottom reboiler of the enrichment tower is located at the bottom of the tower body, and the top condenser of the enrichment tower is located at the top of the tower body; a partition is provided between the bottom and the top of the tower body so that the bottom and the top are not connected;

[0024] The fourth outlet of the recycle gas compressor outlet cooler is sequentially connected to the helium enrichment tower through the demethanation heat exchanger, the bottom reboiler of the enrichment tower, the demethanation heat exchanger, and a fifth throttle valve.

[0025] In one embodiment, the bottom of the tower body of the helium enrichment tower is connected to the input port of the top condenser of the enrichment tower through a pipeline;

[0026] The top condenser of the enrichment tower includes a fifth outlet and a sixth outlet;

[0027] The fifth outlet is connected to the bottom of the tower body of the helium enrichment tower through a pipeline;

[0028] The sixth outlet is connected through the demethanation heat exchanger and the helium purification device for outputting helium gas.

[0029] In one embodiment, the bottom of the helium enrichment column is connected to the external pipeline network through a sixth throttle valve and the demethanation heat exchanger for outputting nitrogen gas.

[0030] In one embodiment, the mixed refrigerant refrigeration cycle system includes multiple circulating cooling circuits;

[0031] The circulating cooling circuit includes a refrigeration cycle main line and a refrigeration cycle branch line;

[0032] On the refrigeration cycle main line, a first-stage mixed refrigerant compressor, an inter-stage cooler, an inter-stage separator, a second-stage mixed refrigerant compressor, a final-stage cooler, and a final-stage separator are sequentially connected;

[0033] On the refrigeration cycle branch line, a liquefaction heat exchanger and multiple throttle valves are provided.

[0034] In one embodiment, the nitrogen refrigeration cycle system includes: a nitrogen refrigeration compressor, a nitrogen refrigeration compressor outlet cooler, and a seventh throttle valve;

[0035] The nitrogen refrigeration compressor is sequentially connected to the nitrogen refrigeration compressor outlet cooler, the demethanation heat exchanger, the seventh throttle valve, and the top condenser of the enrichment column through pipelines to form a circulating cooling circuit.

[0036] In a second aspect, an embodiment of the present invention provides a method for liquefying raw natural gas and co-producing helium extraction by using an integrated natural gas liquefaction and co-producing helium extraction device as described above.

[0037] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0038] The above integrated natural gas liquefaction and co-producing helium extraction device and method provided by the embodiments of the present invention optimize and integrate the natural gas liquefaction and nitrogen removal process and the helium enrichment process to realize the co-production of liquefied natural gas and crude helium gas; by integrating the liquefaction heat exchanger and the denitrification tower into a methane liquefaction system, and integrating the demethanation heat exchanger, the helium enrichment column, the top condenser of the enrichment column, and the reboiler at the bottom of the enrichment column into a methane removal system, and both of the above two systems are respectively integrated in the cold box, the length of the external cold insulation pipeline is reduced, and the cold loss during the helium extraction process is reduced.

[0039] Furthermore, the setting of the circulating gas boosting system takes gas from the outlet of the circulating gas compressor for enrichment, and the natural gas liquefaction system and the demethanation system operate relatively independently, which is beneficial to the start-up commissioning of the device and the improvement of operation stability.

[0040] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention may be realized and attained by the structure particularly pointed out in the written description, claims, as well as the drawings.

[0041] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0042] The drawings are used to provide a further understanding of the present invention, and constitute a part of the description. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0043] Figure 1 It is a schematic structural diagram of an integrated natural gas liquefaction and helium co-production device in an embodiment of the present invention.

[0044] Description of the reference numerals in the drawings:

[0045] 1 - Integrated methane liquefaction system; 2 - Integrated methane removal system;

[0046] 3 - Liquefaction heat exchanger; 4 - Heavy hydrocarbon separation tank; 5 - First throttle valve; 6 - Denitrification tower; 7 - Second throttle valve; 8 - Recycle gas compressor; 9 - Recycle gas compressor outlet cooler; 10 - Third throttle valve;

[0047] 11 - First stage of the mixed refrigerant compressor; 12 - Inter-stage cooler; 13 - Inter-stage separator; 14 - Second stage of the mixed refrigerant compressor; 15 - Final cooler; 16 - Final separator; 17 - Eighth throttle valve; 18 - Ninth throttle valve; 19 - Tenth throttle valve; 20 - Fourth throttle valve;

[0048] 21 - Demethanation heat exchanger; 22 - Reboiler at the bottom of the concentration tower; 23 - Helium concentration tower; 24 - Fifth throttle valve; 25 - Condenser at the top of the concentration tower; 26 - Seventh throttle valve; 27 - Nitrogen refrigeration compressor; 28 - Nitrogen refrigeration compressor outlet cooler; 29 - Sixth throttle valve. Detailed Embodiments

[0049] This embodiment provides an integrated natural gas liquefaction and helium co-production device and method. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0050] An embodiment of the present invention provides an integrated natural gas liquefaction and helium co-production device, as shown in reference to Figure 1 shown, including:

[0051] An integrated methane liquefaction system 1, a mixed refrigerant refrigeration cycle system, an integrated methane removal system 2, and a nitrogen refrigeration cycle system;

[0052] The integrated methane liquefaction system 1 includes a liquefaction heat exchanger 3 and a denitrification tower 6, and the liquefaction heat exchanger 3 and the denitrification tower 6 are connected by pipelines;

[0053] The integrated methane liquefaction system 1 is integrated in a cold box;

[0054] The mixed refrigerant refrigeration cycle system is used to provide cooling capacity for the integrated methane liquefaction system 1;

[0055] The integrated methane removal system 2 includes a demethanation heat exchanger 21 and a helium enrichment tower 23, and the demethanation heat exchanger 21 and the helium enrichment tower 23 are connected by pipelines;

[0056] The integrated methane removal system 2 is integrated in a cold box;

[0057] The nitrogen refrigeration cycle system is used to provide cooling capacity for the integrated methane removal system 2.

[0058] By integrating the integrated methane liquefaction system 1 and the integrated methane removal system 2 into different cold boxes respectively, the length of the external cold insulation pipeline can be reduced, thereby reducing the cooling capacity loss and saving energy consumption.

[0059] Refer to Figure 1 and, in combination with the process, a detailed description is given of the integrated natural gas liquefaction and helium co-production device of the embodiments of the present invention.

[0060] The pretreated raw natural gas (pressure 4000 kPa.a to 6000 kPa.a, temperature 20 to 45 °C) is connected to the liquefaction heat exchanger 3 and the heavy hydrocarbon separation tank 4 in sequence, and the raw natural gas can be transported to the heavy hydrocarbon separation tank 4 through a pipeline. The raw natural gas is precooled in the liquefaction heat exchanger 3, and the precooling temperature is -50 to -70 °C. After entering the heavy hydrocarbon separation tank 4, the heavy hydrocarbons are separated out, that is, the heavy hydrocarbons are in a liquid phase and accumulate at the bottom of the heavy hydrocarbon separation tank 4.

[0061] The gas phase after the heavy hydrocarbon separation is sent out from the two output ports at the top of the heavy hydrocarbon separation tank 4. One gas phase (content 5% to 30%) enters the bottom of the denitrification tower 6 through the first output port and the first throttle valve 5 (throttled to 400 kPa.a to 700 kPa.a); the other gas phase (content 70% to 95%) passes through the second output port, the liquefaction heat exchanger 3 (cooled to -115 to -135 °C) and the second throttle valve 7 (throttled to 400 kPa.a to 700 kPa.a) and enters the denitrification tower 6.

[0062] The top of the denitrification tower 6 is successively connected to the liquefaction heat exchanger 3, the recycle gas compressor 8, the third outlet of the recycle gas compressor outlet cooler 9, the liquefaction heat exchanger 3 and the third throttle valve 10 through pipelines, forming a circulation loop. Therefore, the gas phase at the top of the denitrification tower 6 can flow back into the denitrification tower 6 through this circulation loop. For example, the gas phase at the top of the denitrification tower 6 enters the liquefaction heat exchanger 3 through a pipeline and is reheated to 25 - 35°C, then enters the recycle gas compressor 8 and is pressurized to 3500 kPa.a - 5000 kPa.a. After that, it is cooled to 30 - 40°C by the recycle gas compressor outlet cooler 9. Then, a part of the gas phase (with a content of 75% - 95%) enters the liquefaction heat exchanger 3 through the third outlet and is condensed to -160°C - -170°C. After passing through the third throttle valve 10 (throttled to 400 kPa.a - 700 kPa.a), it enters the top of the denitrification tower 6 as a reflux. This part of the gas phase can be liquefied for the vast majority of methane through low-temperature cooling. Therefore, after circulating into the denitrification tower 6, methane accumulates at the bottom of the decarbonization tower as a liquid phase.

[0063] Another part of the gas phase (with a content of 5% - 25%) passes through the fourth outlet of the recycle gas compressor outlet cooler 9 and is transported to the integrated methane removal system 2.

[0064] A small amount of gas phase (with a content of 5% - 30%) entering the bottom of the denitrification tower 6 from the heavy hydrocarbon separation tank 4 has not undergone the cooling process of the liquefaction heat exchanger 3, so its temperature relative to the methane liquid phase at the bottom is higher. Therefore, a part of the nitrogen gas dissolved in the methane liquid phase can be easily steamed out without the need for additional heat provided by the outside.

[0065] The bottom of the denitrification tower 6 is successively connected to the liquefaction heat exchanger 3, the fourth throttle valve 20 and the liquefied natural gas storage area. The liquid phase (methane) at the bottom of the denitrification tower is transported to the liquefaction heat exchanger 3 through a pipeline and cooled to -155 - -165°C, and then throttled to 200 kPa.a - 250 kPa.a through the fourth throttle valve 20 and transported to the liquefied natural gas storage area through a pipeline.

[0066] Refer to Figure 1 As shown, in the integrated methane removal system 2, the helium enrichment tower 23 specifically includes: a tower body, a reboiler 22 at the bottom of the enrichment tower and a condenser 25 at the top of the enrichment tower; the reboiler 22 at the bottom of the enrichment tower is located at the bottom of the tower body, and the condenser 25 at the top of the enrichment tower is located at the top of the tower body; a partition is provided between the bottom and the top of the tower body to prevent communication between the bottom and the top. The fourth outlet of the recycle gas compressor 8 outlet cooler is connected to the helium enrichment tower 23 successively through the demethanation heat exchanger 21, the reboiler 22 at the bottom of the enrichment tower, the demethanation heat exchanger 21 and the fifth throttle valve 24.

[0067] The natural gas (mainly helium-rich nitrogen gas) enters the integrated methane removal system 2 through the fourth outlet of the cooler 9 at the outlet of the recycle gas compressor, is cooled to -120 to -135 °C by the demethanizer heat exchanger 21, enters the reboiler 22 at the bottom of the concentration tower and exchanges heat with the bottom condensate to -140 to -150 °C, enters the demethanizer heat exchanger 21 again and is further condensed to -150 to -160 °C, and then throttled to 2500 kPa.a to 3500 kPa.a by the fifth throttle valve 24 and enters the upper position above the bottom of the helium concentration tower 23.

[0068] In one embodiment, the bottom of the tower body of the helium concentration tower 23 is connected to the inlet of the top condenser 25 of the concentration tower through a pipeline; the fifth outlet of the top condenser 25 of the concentration tower is connected to the bottom of the tower body of the helium concentration tower 23 for transporting the liquid phase formed after cooling the top condenser 25 of the concentration tower into the tower body; the sixth outlet of the top condenser 25 of the concentration tower is connected to the helium purification device through the demethanizer heat exchanger 21 for outputting the gas phase after passing through the top condenser 25 of the concentration tower, that is, the crude helium gas.

[0069] The gas phase in the tower body of the helium concentration tower 23 enters the top condenser 25 of the concentration tower through a pipeline, is condensed to -175 °C to -185 °C, the nitrogen gas is liquefied into a liquid phase, and then flows back into the tower body of the helium concentration tower 23 through a pipeline. The unliquefied crude helium gas is reheated to 25 to 40 °C through the demethanizer heat exchanger 21 and then transported to the helium purification device through a pipeline for further refining and purifying the helium gas.

[0070] In one embodiment, the bottom of the helium concentration tower 23 is sequentially connected to the sixth throttle valve 29, the demethanizer heat exchanger 21 and the external transmission network, and the gas phase-rich nitrogen gas in the tower can be output. The liquid phase at the bottom of the helium concentration tower 23 is throttled by the sixth throttle valve 29 to 1000 kPa.a to 1500 kPa.a, then enters the demethanizer heat exchanger 21, is reheated to 25 to 40 °C and vaporized, and then transported to the external transmission network.

[0071] In one embodiment, continue to refer to Figure 1 As shown, the mixed refrigerant refrigeration cycle system includes multiple cycle cooling circuits; the cycle cooling circuit includes a refrigeration cycle main line and a refrigeration cycle branch line; the refrigeration cycle main line is provided with a mixed refrigerant compressor stage 11, an inter-stage cooler 12, an inter-stage separator 13, a mixed refrigerant compressor stage 14, a final cooler 15 and a final separator 16 connected in sequence; the refrigeration cycle branch line is provided with a liquefaction heat exchanger 3 and multiple throttle valves, and the connection method can refer to the existing structure.

[0072] For example: The first stage 11 of the mixed refrigerant compressor is connected to the inter-stage cooler 12 and the inter-stage separator 13 through pipelines; the seventh outlet of the inter-stage separator 13 is successively connected to the liquefaction heat exchanger 3, the sixth throttle valve 29, the liquefaction heat exchanger 3 and the inlet of the first stage 11 of the mixed refrigerant compressor through pipelines; the eighth outlet of the inter-stage separator 13 is connected to the inlet of the second stage 14 of the mixed refrigerant compressor through a pipeline; the outlet of the second stage 14 of the mixed refrigerant compressor, the final stage cooler 15 and the final stage separator 16 are successively connected through pipelines; the ninth outlet of the final stage separator 16 is successively connected to the liquefaction heat exchanger 3, the seventh throttle valve 26, the liquefaction heat exchanger 3 and the inlet of the first stage 11 of the mixed refrigerant compressor through pipelines; the tenth outlet of the final stage separator 16 is successively connected to the liquefaction heat exchanger 3, the eighth throttle valve 17, the liquefaction heat exchanger 3 and the inlet of the first stage 11 of the mixed refrigerant compressor through pipelines.

[0073] The medium-pressure liquid-phase mixed refrigerant coming from the inter-stage separator 13 enters the liquefaction heat exchanger 3 and is cooled to -20 to -35 °C, throttled to 300 kPa.a to 400 kPa.a by the sixth throttle valve 29, and then enters the liquefaction heat exchanger 3 to provide high-temperature cold energy for the liquefaction heat exchanger 3; the high-pressure liquid-phase mixed refrigerant coming from the final stage separator 16 enters the liquefaction heat exchanger 3 and is cooled to -55 to -75 °C, throttled to 300 kPa.a to 400 kPa.a by the seventh throttle valve 26, and then enters the liquefaction heat exchanger 3 to provide medium-temperature cold energy; the high-pressure gas-phase mixed refrigerant coming from the final stage separator 16 enters the liquefaction heat exchanger 3 and is cooled to -155 to -165 °C, throttled to 350 kPa.a to 450 kPa.a by the eighth throttle valve 17, and then enters the liquefaction heat exchanger 3 to provide low-temperature cold energy.

[0074] The low-pressure mixed refrigerant after passing through the sixth throttle valve 29, the seventh throttle valve 26 and the eighth throttle valve 17 is combined and reheated to 25 to 35 °C in the liquefaction heat exchanger 3, returns to the inlet of the first stage 11 of the mixed refrigerant compressor, is pressurized to 1000 kPa.a to 1500 kPa.a by the first stage 11 of the mixed refrigerant refrigeration compressor, enters the inter-stage cooler 12 and is cooled to 30 to 40 °C, enters the inter-stage separator 13 for gas-liquid separation, the separated medium-pressure liquid phase is sent to the liquefaction heat exchanger 3, and the separated gas phase is further pressurized to 3000 kPa.a to 4500 kPa.a by the second stage 14 of the mixed refrigerant compressor, enters the final stage cooler 15 and is cooled to 30 to 40 °C, enters the final stage separator 16 for gas-liquid separation, and the separated high-pressure liquid phase and high-pressure gas phase are respectively sent to the liquefaction heat exchanger 3 through the ninth throttle valve 18 and the tenth throttle valve 19. Through analysis, the mixed refrigerant refrigeration cycle system formed by the above components and structures provides the required cold energy for the liquefaction heat exchanger 3.

[0075] In one embodiment, refer to Figure 1As shown in the figure, the nitrogen refrigeration cycle system includes: a nitrogen refrigeration compressor 27, an outlet cooler of the nitrogen refrigeration compressor 27, and a seventh throttle valve 26; the nitrogen refrigeration compressor 27 is sequentially connected to the outlet cooler of the nitrogen refrigeration compressor 27, the demethanizer heat exchanger 21, the seventh throttle valve 26, and the condenser at the top of the concentration tower 25 through pipelines to form a circulating cooling loop.

[0076] The nitrogen refrigerant (with a pressure of 1500 kPa.a to 2500 kPa.a and a temperature of 30 to 40 °C) coming from the outlet cooler 28 of the nitrogen refrigeration compressor enters the demethanizer heat exchanger 21 and is cooled to -175 to -185 °C, throttled to 350 kPa.a to 550 kPa.a through the ninth throttle valve 18, enters the condenser at the top of the concentration tower 25 and vaporizes therein, then enters the demethanizer heat exchanger 21 to be reheated to 25 to 40 °C, enters the nitrogen refrigeration compressor 27 to be pressurized to 1500 kPa.a to 2500 kPa.a, is cooled to 30 to 40 °C through the outlet cooler 28 of the nitrogen refrigeration compressor, and enters the demethanizer heat exchanger 21. Through analysis, the nitrogen refrigeration cycle formed by the above components and structures provides the required cooling capacity for the demethanizer heat exchanger 21 and the condenser at the top of the concentration tower 25.

[0077] Based on the same inventive concept, the embodiment of the present invention also provides a method for liquefying raw natural gas and co-producing helium extraction by using an integrated natural gas liquefaction and co-producing helium extraction device. Since the principle of this method is similar to that of the aforementioned integrated natural gas liquefaction and co-producing helium extraction device, the implementation of this method can refer to the implementation of the aforementioned device, and the repeated parts will not be elaborated here.

[0078] Obviously, those skilled in the art can make various changes to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes.

Claims

1. An integrated natural gas liquefaction and helium extraction co-production device, characterized in that, Comprising: An integrated methane liquefaction system, a mixed refrigerant refrigeration cycle system, an integrated methane removal system, and a nitrogen refrigeration cycle system; The integrated methane liquefaction system includes a liquefaction heat exchanger and a denitrification tower, and the liquefaction heat exchanger and the denitrification tower are connected by pipelines; The integrated methane liquefaction system is integrated in a liquefaction cold box; The mixed refrigerant refrigeration cycle system is used to provide cooling capacity for the integrated methane liquefaction system; The integrated methane removal system includes a demethanation heat exchanger and a helium enrichment tower, and the demethanation heat exchanger and the helium enrichment tower are connected by pipelines; The integrated methane removal system is integrated in a demethanation cold box; The nitrogen refrigeration cycle system is used to provide cooling capacity for the integrated methane removal system.

2. The device according to claim 1, characterized in that, The device further includes: a heavy hydrocarbon separation tank; The heavy hydrocarbon separation tank, the liquefaction heat exchanger, and the raw natural gas are connected in sequence; The heavy hydrocarbon separation tank is used to receive the raw natural gas and remove the heavy hydrocarbons in the raw natural gas.

3. The device according to claim 2, characterized in that, The top of the heavy hydrocarbon separation tank includes a first output port and a second output port. The first output port is connected to the bottom of the denitrification tower through a first throttle valve; the second output port is connected to the denitrification tower through the liquefaction heat exchanger and a second throttle valve.

4. The device according to claim 1, characterized in that, The device further includes: a recycle gas boosting system; The recycle gas boosting system includes a recycle gas compressor and a recycle gas compressor outlet cooler; The recycle gas compressor and the recycle gas compressor outlet cooler are connected.

5. The device according to claim 4, characterized in that, The recycle gas compressor outlet cooler includes a third output port; The top of the denitrification tower is connected to the third output port of the liquefaction heat exchanger, the recycle gas compressor, the recycle gas compressor outlet cooler, the liquefaction heat exchanger, and a third throttle valve through pipelines in sequence to form a circulation loop; The bottom of the denitrification tower is connected to the liquefied natural gas storage tank area through the liquefaction heat exchanger and a fourth throttle valve to send the liquefied natural gas to the liquefied natural gas storage tank area.

6. The device according to claim 5, characterized in that The helium enrichment tower includes: a tower body, a bottom reboiler of the enrichment tower, and a top condenser of the enrichment tower; the recycle gas compressor outlet cooler further includes: a fourth output port; The bottom reboiler of the enrichment tower is located at the bottom of the tower body, and the top condenser of the enrichment tower is located at the top of the tower body; a partition is provided between the bottom and the top of the tower body to prevent direct communication between the bottom and the top; The fourth output port of the recycle gas compressor outlet cooler is connected to the helium enrichment tower through the demethanation heat exchanger, the bottom reboiler of the enrichment tower, the demethanation heat exchanger, and a fifth throttle valve in sequence.

7. The device according to claim 6, characterized in that, The bottom of the tower body of the helium enrichment tower is connected to the input port of the top condenser of the enrichment tower through a pipeline; The top condenser of the enrichment tower includes a fifth output port and a sixth output port; The fifth output port is connected to the bottom of the tower body of the helium enrichment tower through a pipeline; The sixth output port is connected to a crude helium output device through the demethanation heat exchanger for outputting crude helium.

8. The device according to claim 4, characterized in that, The bottom of the helium enrichment tower is connected to an external transmission pipeline network through a sixth throttle valve and the demethanation heat exchanger for outputting nitrogen and methane.

9. The device according to any one of claims 1-8, characterized in that, The mixed refrigerant refrigeration cycle system includes multiple cycle cooling circuits; The described circulating cooling circuit includes a refrigeration cycle main line and a refrigeration cycle branch line; On the refrigeration cycle main line, there are successively connected a first-stage mixed refrigerant compressor, an inter-stage cooler, an inter-stage separator, a second-stage mixed refrigerant compressor, a final-stage cooler, and a final-stage separator; On the refrigeration cycle branch line, there are arranged a liquefaction heat exchanger and a plurality of throttle valves.

10. The device according to any one of claims 1-8, characterized in that, The nitrogen refrigeration cycle system includes: a nitrogen refrigeration compressor, a nitrogen refrigeration compressor outlet cooler, and a seventh throttle valve; The nitrogen refrigeration compressor is successively connected to the nitrogen refrigeration compressor outlet cooler, the demethanizer heat exchanger, the seventh throttle valve, and the enriching tower top condenser through pipelines to form a circulating cooling circuit.

11. A method for liquefying raw natural gas and co-producing helium extraction by using the integrated natural gas liquefaction and helium extraction co-production device according to any one of claims 1-10.

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