A process for the production of helium from natural gas by co-production of ethane and LNG

Abstract

The present application relates to a kind of natural gas helium production process of co-production of ethane and LNG.This application includes ethane recovery unit, crude helium extraction unit, heat exchange unit, propane precooling system, mixed refrigerant refrigeration system.Ethane recovery unit mainly includes gas-liquid separator, compressor, expander and demethanizer;Crude helium extraction unit mainly includes first-stage helium extraction tower and secondary helium extraction tower;Heat exchange unit mainly includes heat exchanger;Propane precooling system mainly includes compressor, cooler, gas-liquid separator and throttle valve;Mixed refrigerant refrigeration system mainly includes compressor, cooler and throttle valve.This production process uses propane precooling, mixed refrigerant refrigeration, ethane recovery, double-tower low-temperature rectification helium extraction technical scheme, while producing ethane, LNG and crude helium.The process is under the same conditions as other processes, helium and ethane recovery rate is high, device operating temperature is low and energy consumption is low, LNG liquefaction rate is high.

Description

Technical Field

[0001] This invention belongs to the field of chemical separation technology and relates to helium extraction from natural gas, specifically a natural gas helium extraction process that co-produces ethane and LNG. Background Technology

[0002] Helium, as an important strategic and scarce resource, is widely used in many fields such as medicine, aerospace, and new energy development due to its excellent thermal conductivity and diffusivity, and has high market application value. Helium resources are mainly found in natural gas. Because the helium content in the air is extremely low, separating helium from the air is very difficult and energy-intensive. Therefore, helium extraction both domestically and internationally is mainly done through extraction from natural gas.

[0003] With the development of high technology, the demand for helium is increasing. Therefore, reducing helium imports, achieving domestic helium production, and comprehensively and efficiently developing and utilizing helium resources will help alleviate the urgent need for helium supply in the country, play an important role in the multi-energy utilization of gas fields and improving overall efficiency, and also maintain the stable development of my country's helium market.

[0004] Traditional helium extraction processes mainly include cryogenic methods, pressure swing adsorption (PSA), and membrane separation. With the rapid development of helium extraction technology, considering the high energy consumption, high investment, low extraction efficiency, and economic costs of traditional processes, technological innovations such as multi-product co-production and helium extraction have emerged. These innovations have not only significantly improved the economics of helium extraction but also increased helium recovery rates and substantially reduced energy consumption and equipment investment costs. Therefore, future helium extraction technology will definitely not be a single production process but rather an integration of multiple processes or multi-product co-production.

[0005] Given the low helium concentration in my country's natural gas while achieving higher production volumes, a natural gas-to-helium extraction process that co-produces ethane and LNG is the optimal choice for the helium extraction industry. The original helium extraction process aims to extract helium while producing LNG as a byproduct, resulting in a low liquefaction rate. However, by adopting a liquefied natural gas (LNG) process, helium and ethane are produced as byproducts, and the helium recovery rate can reach over 90%, making its economic benefits significantly higher than the original process.

[0006] In summary, helium extraction from natural gas faces challenges due to high energy consumption and costs. To address these issues, a helium extraction process combining ethane and LNG is proposed. This process integrates the production of all three products, allowing for shared pretreatment and utilities, reducing investment and operating costs, and making the ethane-LNG combined helium extraction process competitive in the market. In the context of liquefied natural gas (LNG) as the primary source, maximizing helium extraction efficiency while recovering residual cold energy from the liquefaction process, thereby reducing investment and operating costs and improving the economics of the plant, remains a significant challenge in the field of natural gas helium extraction. Summary of the Invention

[0007] To address the problems of high energy consumption, large investment, and high operating costs in current natural gas helium extraction technologies, this invention aims to provide a natural gas helium extraction process that co-produces ethane and LNG. This process employs ethane recovery, crude helium extraction, propane precooling, and mixed refrigerant refrigeration. LNG is the main product, with helium production and ethane recovery as byproducts. This device effectively solves the problems of high energy consumption, large investment, and high operating costs in current LNG co-production natural gas helium extraction processes. It retains some advantages of natural gas liquefaction to reduce investment costs in helium production, while simultaneously producing helium and LNG, recovering ethane, and realizing the recovery and utilization of cold energy during LNG production.

[0008] To achieve the above objectives, the present invention provides a natural gas helium extraction process for the co-production of ethane and LNG, comprising an ethane recovery unit, a crude helium extraction unit, a heat exchange unit, a propane precooling system, and a mixed refrigerant refrigeration system connected by pipelines.

[0009] The ethane recovery unit includes a gas-liquid separator V-105, a throttle valve VLV-107, a compressor K-106, an expander K-107, a throttle valve VLV-108, a throttle valve VLV-109, and a demethanizer T-103; the crude helium extraction unit includes a primary helium extraction tower T-101, a top cooler H-101, a bottom reboiler H-102, a throttle valve VLV-106, a secondary helium extraction tower T-102, a top cooler H-103, and a bottom reboiler H-104; the heat exchange unit includes heat exchangers LNG-100, LNG-101, LNG-102, LNG-103, and LNG... -104, heat exchanger LNG-105; the propane precooling system includes compressor K-100, cooler E-100, throttle valve VLV-100, gas-liquid separator V-101, throttle valve VLV-101, gas-liquid separator V-102, throttle valve VLV-102, gas-liquid separator V-103, compressor K-102, compressor K-101; the mixed refrigerant refrigeration system includes compressor K-105, cooler E-103, compressor K-104, cooler E-102, compressor K-103, cooler E-101, gas-liquid separator V-104, throttle valve VLV-103, throttle valve VLV-104;

[0010] The ethane recovery unit has a feed gas inlet pipe connected to heat exchanger LNG-100. Heat exchangers LNG-100, LNG-101, and LNG-102 are sequentially connected, pre-cooling and cryogenically cooling the feed gas before it enters gas-liquid separator V-105. At the top of gas-liquid separator V-105, one branch is sequentially connected to expander K-107 and demethanizer T-103, and the other branch is sequentially connected to heat exchanger LNG-105 and throttle valve VLV-109. Gas-liquid separator V-10... 5. The bottom of the demethanizer, the throttling valve VLV-107, and the demethanizer T-103 are connected in sequence; the top of the demethanizer T-103, the heat exchanger LNG-105, the compressor K-106, and the heat exchanger LNG-103 are connected in sequence, with one stream flowing back to the top of the demethanizer T-103 through the heat exchanger LNG-105 and the throttling valve VLV-108; two side streams from the bottom of the demethanizer T-103 enter the heat exchanger LNG-102 to recover cold energy; condensate product is discharged from the bottom of the demethanizer T-103;

[0011] In the crude helium extraction unit, dry gas from the ethane recovery unit enters the heat exchanger LNG-103 for deep cooling before entering the primary helium extraction tower T-101. The primary helium extraction tower T-101, the top cooler H-101, the heat exchanger LNG-104, the throttle valve VLV-106, and the secondary helium extraction tower T-102 are sequentially connected for crude helium extraction. The primary helium extraction tower T-101, the bottom reboiler H-102, the heat exchanger LNG-104, and the throttle valve VLV-106 are also connected. 05. Gas-liquid separator V-106 is connected in sequence to produce LNG product, which enters the LNG storage tank; the helium gas discharged from the secondary helium extraction tower T-102 and the tower top cooler H-103 passes through heat exchangers LNG-104, LNG-103, LNG-102, LNG-101, and LNG-100 in sequence to the crude helium storage tank; liquid nitrogen is discharged from the secondary helium extraction tower T-102 and the tower bottom reboiler H-104 and goes to the liquid nitrogen storage tank.

[0012] In the propane precooling system, propane, after being depressurized by the throttling valve VLV-100, enters the gas-liquid separator V-101 and is separated into gas and liquid phases. The liquid phase at the bottom of the gas-liquid separator V-101 is divided into two parts: one part returns to the heat exchanger LNG-100 to provide cooling, and the other part, after being throttled by the throttling valve VLV-101, enters the gas-liquid separator V-102 and is separated into gas and liquid phases. The liquid phase at the bottom of the gas-liquid separator V-102 is also divided into two parts: one part returns to the heat exchanger LNG-101 to provide cooling, and the other part, after being throttled by the throttling valve VLV-102, enters the gas-liquid separator V-103 and is separated into gas and liquid phases. The liquid phase is two-phase; the liquid phase at the bottom of the gas-liquid separator V-103 is returned to the heat exchanger LNG-102 to provide it with the required cooling capacity; after the heat exchanger LNG-102 exchanges heat with the refrigerant, it mixes with the gas phase at the top of the gas-liquid separator V-103. After being compressed by the compressor K-102 and mixed with the refrigerant after exchanging heat with the heat exchanger LNG-101, it is compressed by the compressor K-101 and mixed with the refrigerant after exchanging heat with the heat exchanger LNG-101 and the gas phase at the top of the gas-liquid separator V-101. After being compressed by the compressor K-100 and cooled by the cooler E-100 to the initial state, the propane precooling cycle is completed.

[0013] In the mixed refrigerant refrigeration system, the mixed refrigerant sequentially passes through compressor K-105, cooler E-103, compressor K-104, cooler E-102, compressor K-103, and cooler E-101, undergoing three stages of compression and cooling before entering heat exchanger LNG-100. Heat exchangers LNG-100, LNG-101, and LNG-102, along with gas-liquid separator V-104, are sequentially connected. The gas phase at the top of gas-liquid separator V-104 sequentially passes through the heat exchanger... After being cooled by LNG-103 and LNG-104, and throttled by the expansion valve VLV-104, the LNG-103 and LNG-104 return to provide the required cooling capacity. Finally, the LNG-103 enters the inlet of the compressor K-105 to complete the mixed refrigerant refrigeration cycle. The liquid phase at the bottom of the gas-liquid separator V-104 enters the LNG-103 and is further cooled. After being throttled by the expansion valve VLV-103, the liquid phase then merges with the cryogenic mixed refrigerant that has been heated by the LNG-104.

[0014] The above-mentioned natural gas helium extraction process for the co-production of ethane and LNG can use helium-containing natural gas at ambient temperature and any pressure, and the applicable range of raw gas conditions is relatively wide.

[0015] The aforementioned natural gas helium extraction process for the co-production of ethane and LNG includes heat exchangers LNG-100, LNG-101, LNG-102, LNG-103, LNG-104, and LNG-105. Their main function is to achieve heat exchange and transfer during the production process, and they are conventional equipment in the field. In this invention, heat exchanger LNG-100 is provided with a first heat exchange channel, a second heat exchange channel, a third heat exchange channel, and a fourth heat exchange channel.

[0016] The raw material gas inlet pipe is connected to the first end of the fourth heat exchange channel, and the end of the fourth heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the first heat exchange channel is connected to the top pipe of the gas-liquid separator V-101 via a pipe, and the end of the first heat exchange channel is connected to the bottom of the gas-liquid separator V-101 via a pipe; the first end of the second heat exchange channel is connected to the crude helium export pipe via a pipe, and the end of the second heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the third heat exchange channel is connected to the outlet of the cooler E-101 via a pipe, and the end of the third heat exchange channel is connected to the LNG-101 heat exchanger via a pipe.

[0017] In this invention, the heat exchanger LNG-101 is provided with a fifth heat exchange channel, a sixth heat exchange channel, a seventh heat exchange channel, and an eighth heat exchange channel;

[0018] The first end of the fifth heat exchange channel is connected to the top pipe of the gas-liquid separator V-102 via a pipe, and the last end of the fifth heat exchange channel is connected to the bottom of the gas-liquid separator V-102 via a pipe; the first end of the sixth heat exchange channel is connected to the last end of the second heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the sixth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the seventh heat exchange channel is connected to the last end of the third heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the seventh heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the eighth heat exchange channel is connected to the last end of the fourth heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the eighth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe.

[0019] In this invention, the heat exchanger LNG-102 is provided with a ninth heat exchange channel, a tenth heat exchange channel, an eleventh heat exchange channel, a twelfth heat exchange channel, a thirteenth heat exchange channel, and a fourteenth heat exchange channel.

[0020] The first end of the ninth heat exchange channel is connected to the top pipe of the gas-liquid separator V-103 via a pipe, and the last end of the ninth heat exchange channel is connected to the bottom of the gas-liquid separator V-103 via a pipe; the first end of the tenth heat exchange channel is connected to the last end of the sixth heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the tenth heat exchange channel is connected to heat exchanger LNG-03 via a pipe; the first end of the eleventh heat exchange channel is connected to the last end of the seventh heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the eleventh heat exchange channel is connected to the gas-liquid separator via a pipe. V-104 is connected; the first end of the twelfth heat exchange channel is connected to the end of the eighth heat exchange channel of LNG-101 via a pipeline, and the twelfth heat exchange channel is connected to the gas-liquid separator V-105 via a pipeline; the first end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline; the first end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline.

[0021] In this invention, the heat exchanger LNG-103 is provided with a fifteenth heat exchange channel, a sixteenth heat exchange channel, a seventeenth heat exchange channel, an eighteenth heat exchange channel, and a nineteenth heat exchange channel;

[0022] The first end of the fifteenth heat exchange channel is connected to the inlet of compressor K-105 via a pipeline, and the last end of the fifteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the sixteenth heat exchange channel is connected to the bottom of gas-liquid separator V-104 via a pipeline, and the last end of the sixteenth heat exchange channel is connected to throttle valve VLV-103 via a pipeline; the first end of the seventeenth heat exchange channel is connected to the top of gas-liquid separator V-104 via a pipeline, and the last end of the seventeenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the eighteenth heat exchange channel is connected to the last end of the tenth heat exchange channel of heat exchanger LNG-102 via a pipeline, and the last end of the eighteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the nineteenth heat exchange channel is connected to the booster outlet of turbine expander K-106 via a pipeline, and the last end of the nineteenth heat exchange channel is connected to the first-stage helium extraction tower T-101 via a pipeline.

[0023] In this invention, the heat exchanger LNG-104 is provided with a twentieth heat exchange channel, a twentieth eleventh heat exchange channel, a twentieth twentieth heat exchange channel, a twentieth thirteenth heat exchange channel, and a twentieth twentieth heat exchange channel.

[0024] The 20th heat exchange channel is connected via a pipeline to the end of the 15th heat exchange channel of heat exchanger LNG-103, and the end of the 20th heat exchange channel is connected via a pipeline to the throttle valve VLV-104; the 21st heat exchange channel is connected via a pipeline to the end of the 18th heat exchange channel of heat exchanger LNG-103, and the end of the 21st heat exchange channel is connected via a pipeline to the secondary helium extraction tower T-102 and the tower top cooler H-103; the 22nd heat exchange channel is connected via a pipeline to the 17th heat exchange channel of heat exchanger LNG-103. The ends of the twenty-second heat exchange channel are connected to the throttle valve VLV-104 via pipes; the beginning of the twenty-third heat exchange channel is connected to the first-stage helium extraction tower T-101 and the top cooler H-101 via pipes, and the end of the twenty-third heat exchange channel is connected to the throttle valve VLV-106 via pipes; the beginning of the twenty-fourth heat exchange channel is connected to the first-stage helium extraction tower T-101 and the bottom reboiler H-102 via pipes, and the end of the twenty-fourth heat exchange channel is connected to the throttle valve VLV-105 via pipes.

[0025] In this invention, the heat exchanger LNG-105 is provided with a 25th heat exchange channel, a 26th heat exchange channel, and a 27th heat exchange channel;

[0026] The first end of the 25th heat exchange channel is connected to the inlet of compressor K-106 via a pipeline, and the last end of the 25th heat exchange channel is connected to the top of demethanizer T-103 via a pipeline; the first end of the 26th heat exchange channel is connected to the return dry gas pipeline via a pipeline, and the last end of the 26th heat exchange channel is connected to throttle valve VLV-108 via a pipeline; the first end of the 27th heat exchange channel is connected to the top of gas-liquid separator V-105 via a pipeline, and the last end of the 27th heat exchange channel is connected to throttle valve VLV-109 via a pipeline.

[0027] The aforementioned natural gas helium extraction process for the co-production of ethane and LNG comprises an ethane recovery loop consisting of the fourth heat exchange channel of heat exchanger LNG-100, the eighth heat exchange channel of heat exchanger LNG-101, the twelfth heat exchange channel of heat exchanger LNG-102, gas-liquid separator V-105, heat exchanger LNG-105, demethanizer T-103, and connecting pipes between adjacent components; and a helium recovery loop consisting of the nineteenth heat exchange channel of heat exchanger LNG-103, primary helium extraction tower T-100, tower top cooler H-101, heat exchanger LNG-104's twenty-third heat exchange channel, throttle valve VLV-106, secondary helium extraction tower T-101, and tower top cooler. The crude helium production circuit consists of heat exchanger H-103, the 21st heat exchange channel of heat exchanger LNG-104, the 18th heat exchange channel of heat exchanger LNG-103, the 10th heat exchange channel of heat exchanger LNG-102, the 6th heat exchange channel of heat exchanger LNG-101, the 2nd heat exchange channel of heat exchanger LNG-100, and the connecting pipes between adjacent components. The LNG production circuit consists of the first-stage helium extraction tower T-100, the reboiler H-102 at the bottom of the tower, the 24th heat exchange channel of heat exchanger LNG-104, the throttle valve VLV-105, the gas-liquid separator V-106, the LNG storage tank, and the connecting pipes between adjacent components.

[0028] The aforementioned natural gas helium extraction process, which co-produces ethane and LNG, uses a propane precooling system to provide cooling for heat exchangers LNG-100, LNG-101, and LNG-102, and employs propane as the circulating refrigerant.

[0029] The aforementioned natural gas helium extraction process for the co-production of ethane and LNG uses a mixed refrigerant refrigeration system to provide cooling for heat exchangers LNG-103 and LNG-104, employing a mixed refrigerant composed of nitrogen, methane, ethane, and propane as the circulating refrigerant.

[0030] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0031] (1) The natural gas helium extraction process provided by this invention, applicable to the co-production of ethane and LNG, involves the distillation and separation of helium in the feed gas through a heat exchanger, a primary helium extraction tower, and a secondary helium extraction tower, thereby increasing the helium concentration in the gaseous material. The feed gas then passes through a five-stage heat exchanger and a secondary distillation tower to obtain crude helium. The natural gas is then liquefied through the five-stage heat exchanger to obtain LNG. The residual cold energy generated during the LNG and helium production process is utilized through the heat exchanger to recover ethane from the feed gas. This invention integrates three processes: traditional natural gas liquefaction, natural gas helium extraction, and natural gas ethane recovery. This integration reduces equipment investment and allows for the recycling of cold energy, minimizing resource waste. Furthermore, it significantly increases the extracted helium concentration, which helps reduce the energy consumption of subsequent separation in the extraction of refined helium and reduces overall cold energy loss in the unit.

[0032] (2) The natural gas helium extraction process for co-production of ethane and LNG provided by the present invention adopts propane pre-cooling and mixed refrigerant refrigeration process in the crude helium extraction part, which produces crude helium product with high concentration, high helium recovery rate, low overall energy consumption of the unit, low minimum operating temperature of the unit, high LNG liquefaction rate and low equipment investment.

[0033] (3) The natural gas helium extraction process for co-production of ethane and LNG provided by the present invention utilizes the residual cooling capacity of LN6 and helium production process directly by using heat exchangers in the ethane recovery unit. This not only achieves the purpose of recovering ethane from the raw gas, but also reduces the investment in equipment specifically for ethane recovery from the raw gas.

[0034] (4) The natural gas helium extraction process applicable to the co-production of ethane and LNG provided by the present invention improves the economics of natural gas helium extraction, making the natural gas helium extraction process of ethane and LNG economically competitive, which is of great significance. It helps to further promote the development of low-helium natural gas helium extraction technology, drive the research and development and improvement of related industry equipment and materials, thereby supporting the development of domestic high-tech industries and effectively guaranteeing the helium demand in aerospace, medical and new energy fields. Attached Figure Description

[0035] Figure 1 This is a flow chart of the natural gas helium extraction process for the co-production of ethane and LNG according to the present invention;

[0036] Explanation of reference numerals in the attached diagram: K-100 - Compressor; E-100 - Cooler; VLV-100 - Throttling valve; V-101 - Gas-liquid separator; VLV-101 - Throttling valve; V-102 - Gas-liquid separator; VLV-102 - Throttling valve; V-103 - Gas-liquid separator; K-102 - Compressor; K-101 - Compressor; K-105 - Compressor; E-103 - Cooler; K-104 - Compressor; E-102 - Cooler; K-103 - Compressor; E-101 - Cooler; LNG-100 - Heat exchanger; LNG-101 - Heat exchanger; LNG-102 - Heat exchanger; V-105 - Heat exchanger; K-106 - Compressor Compressor; K-107 - Expander; LNG-105 - Heat exchanger; VLV-107 - Throttling valve; VLV-108 - Throttling valve; VLV-109 - Throttling valve; T-103 - Demethanizer; V-104 - Gas-liquid separator; LNG-103 - Heat exchanger; VLV-103 - Throttling valve; T-101 - Primary helium extraction tower; H-101 - Cooler; H-102 - Reboiler; LNG-104 - Heat exchanger; VLV-105 - Throttling valve; V-106 - Gas-liquid separator; VLV-106 - Throttling valve; T-102 - Secondary helium extraction tower; H-103 - Cooler; H-104 - Reboiler; VLV-104 - Throttling valve. Detailed Implementation

[0037] The following will be combined with the appendix Figure 1 The present invention provides a clear and complete description of the natural gas helium extraction process technology solution for the co-production of ethane and LNG. Obviously, the described embodiments are only a part of the embodiments of the present invention.

[0038] This embodiment provides a natural gas helium extraction process for the co-production of ethane and LNG, such as... Figure 1 As shown, it includes an ethane recovery unit, a crude helium extraction unit, a heat exchange unit, a propane precooling system, and a mixed refrigerant refrigeration system connected by pipelines.

[0039] The ethane recovery unit includes a gas-liquid separator V-105, a throttle valve VLV-107, a compressor K-106, an expander K-107, a throttle valve VLV-108, a throttle valve VLV-109, and a demethanizer T-103.

[0040] The crude helium extraction unit includes a primary helium extraction tower T-101, a top cooler H-101, a bottom reboiler H-102, a throttling valve VLV-106, a secondary helium extraction tower T-102, a top cooler H-103, and a bottom reboiler H-104.

[0041] The heat exchange unit includes heat exchangers LNG-100, LNG-101, LNG-102, LNG-103, LNG-104, and LNG-105. Heat exchanger LNG-100 contains a first, second, third, and fourth heat exchange channel. Heat exchanger LNG-101 contains a fifth, sixth, seventh, and eighth heat exchange channel. Heat exchanger LNG-102 contains a ninth, tenth, eleventh, twelfth, thirteenth, and fourteenth heat exchange channel. Heat exchanger LNG-103 contains a fifteenth, sixteenth, seventeenth, eighteenth, and nineteenth heat exchange channel. Heat exchanger LNG-104 is equipped with the twentieth, twenty-first, twenty-second, twenty-third, and twenty-fourth heat exchange channels. Heat exchanger LNG-105 is equipped with the twenty-fifth, twenty-sixth, and twenty-seventh heat exchange channels.

[0042] The propane precooling system includes compressor K-100, cooler E-100, throttle valve VLV-100, gas-liquid separator V-101, throttle valve VLV-102, throttle valve VLV-102, gas-liquid separator V-103, compressor K-102, and compressor K-101.

[0043] The mixed refrigerant refrigeration system includes compressor K-105, cooler E-103, compressor K-104, cooler E-102, compressor K-103, cooler E-101, gas-liquid separator V-104, throttle valve VLV-103, and throttle valve VLV-104.

[0044] The raw material gas inlet pipe is connected to the first end of the fourth heat exchange channel, and the end of the fourth heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the first heat exchange channel is connected to the top pipe of the gas-liquid separator V-101 via a pipe, and the end of the first heat exchange channel is connected to the bottom of the gas-liquid separator V-101 via a pipe; the first end of the second heat exchange channel is connected to the crude helium export pipe via a pipe, and the end of the second heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the third heat exchange channel is connected to the outlet of the cooler E-101 via a pipe, and the end of the third heat exchange channel is connected to the LNG-101 heat exchanger via a pipe.

[0045] The first end of the fifth heat exchange channel is connected to the top pipe of the gas-liquid separator V-102 via a pipe, and the last end of the fifth heat exchange channel is connected to the bottom of the gas-liquid separator V-102 via a pipe; the first end of the sixth heat exchange channel is connected to the last end of the second heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the sixth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the seventh heat exchange channel is connected to the last end of the third heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the seventh heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the eighth heat exchange channel is connected to the last end of the fourth heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the eighth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe.

[0046] The first end of the ninth heat exchange channel is connected to the top pipe of the gas-liquid separator V-103 via a pipe, and the last end of the ninth heat exchange channel is connected to the bottom of the gas-liquid separator V-103 via a pipe; the first end of the tenth heat exchange channel is connected to the last end of the sixth heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the tenth heat exchange channel is connected to heat exchanger LNG-03 via a pipe; the first end of the eleventh heat exchange channel is connected to the last end of the seventh heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the eleventh heat exchange channel is connected to the gas-liquid separator via a pipe. V-104 is connected; the first end of the twelfth heat exchange channel is connected to the end of the eighth heat exchange channel of the LNG-101 heat exchanger via a pipeline, and the twelfth heat exchange channel is connected to the gas-liquid separator V-105 via a pipeline; the first end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline; the first end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline.

[0047] The first end of the fifteenth heat exchange channel is connected to the inlet of compressor K-105 via a pipeline, and the last end of the fifteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the sixteenth heat exchange channel is connected to the bottom of gas-liquid separator V-104 via a pipeline, and the last end of the sixteenth heat exchange channel is connected to throttle valve VLV-103 via a pipeline; the first end of the seventeenth heat exchange channel is connected to the top of gas-liquid separator V-104 via a pipeline, and the last end of the seventeenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the eighteenth heat exchange channel is connected to the last end of the tenth heat exchange channel of heat exchanger LNG-102 via a pipeline, and the last end of the eighteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the nineteenth heat exchange channel is connected to the booster outlet of turbine expander K-106 via a pipeline, and the last end of the nineteenth heat exchange channel is connected to the first-stage helium extraction tower T-101 via a pipeline.

[0048] The 20th heat exchange channel is connected via a pipeline to the end of the 15th heat exchange channel of heat exchanger LNG-103, and the end of the 20th heat exchange channel is connected via a pipeline to the throttle valve VLV-104; the 21st heat exchange channel is connected via a pipeline to the end of the 18th heat exchange channel of heat exchanger LNG-103, and the end of the 21st heat exchange channel is connected via a pipeline to the secondary helium extraction tower T-102 and the tower top cooler H-103; the 22nd heat exchange channel is connected via a pipeline to the 17th heat exchange channel of heat exchanger LNG-103. The ends of the twenty-second heat exchange channel are connected to the throttle valve VLV-104 via pipes; the beginning of the twenty-third heat exchange channel is connected to the first-stage helium extraction tower T-101 and the top cooler H-101 via pipes, and the end of the twenty-third heat exchange channel is connected to the throttle valve VLV-106 via pipes; the beginning of the twenty-fourth heat exchange channel is connected to the first-stage helium extraction tower T-101 and the bottom reboiler H-102 via pipes, and the end of the twenty-fourth heat exchange channel is connected to the throttle valve VLV-105 via pipes.

[0049] The first end of the 25th heat exchange channel is connected to the inlet of compressor K-106 via a pipeline, and the last end of the 25th heat exchange channel is connected to the top of demethanizer T-103 via a pipeline; the first end of the 26th heat exchange channel is connected to the return dry gas pipeline via a pipeline, and the last end of the 26th heat exchange channel is connected to throttle valve VLV-108 via a pipeline; the first end of the 27th heat exchange channel is connected to the top of gas-liquid separator V-105 via a pipeline, and the last end of the 27th heat exchange channel is connected to throttle valve VLV-109 via a pipeline.

[0050] The aforementioned helium extraction process from natural gas used in the co-production of ethane and LNG can utilize helium-containing natural gas at ambient temperature and any pressure, making it applicable to a wide range of feedstock conditions. The following detailed description uses helium-containing natural gas as the feedstock for helium extraction in this embodiment. The feedstock gas pressure is 6.0 MPa, the temperature is 20°C, and the processing capacity is 5 × 10⁵ m³. 3 / d. The main components of the feed gas are methane 79.54%, ethane 2.94%, propane 4.51%, isobutane 1.25%, n-butane 2.4%, isopentane 0.93%, n-pentane 0.85%, n-hexane 1%, nitrogen 6.36%, and helium 0.21%.

[0051] The feed gas inlet pipe is connected to heat exchanger LNG-100. After heat exchange in heat exchangers LNG-100, LNG-101, and LNG-102, the feed gas temperature drops to -35℃, and then enters gas-liquid separator V-105. The gas phase discharged from the top of gas-liquid separator V-105 has two streams: one stream passes through expander K-107 and enters the top of demethanizer T-103; the other stream passes through the 27th heat exchange channel of heat exchanger LNG-105, is throttled by throttling valve VLV-107, and then enters the top of demethanizer T-103. The liquid phase at the bottom of gas-liquid separator V-105 is throttled by throttling valve VLV-107 and enters the middle of demethanizer T-103. The gas flowing out from the top of T-103 has a methane volume fraction of 97.55% and an ethane volume fraction of 1.21%. It then passes through the 25th heat exchange channel of heat exchanger LNG-105 and compressor K-106, and is discharged to the 19th heat exchange channel of heat exchanger LNG-103. One stream flows back to the top of demethanizer T-103 through the 26th heat exchange channel of heat exchanger LNG-10 and throttle valve VLV-108. Two side streams from demethanizer T-103 enter heat exchanger LNG-102 to recover cold energy. The condensate product discharged from the bottom of demethanizer T-103 has an ethane volume fraction of 75.23% and a methane volume fraction of 0.46%, with an ethane recovery rate of 92.14%.

[0052] The dry gas exiting the ethane recovery unit enters the nineteenth heat exchange channel of heat exchanger LNG-103 at a temperature of -60°C, and then enters the primary helium extraction tower T-101. The gas discharged from the primary helium extraction tower T-101 and the top cooler H-101 has a helium content of 4.88% and a temperature of -135.7°C. It then passes sequentially through the twenty-third heat exchange channel of heat exchanger LNG-104 and the throttling valve VLV-106 before entering the secondary helium extraction tower T-102. The helium concentration discharged from the secondary helium extraction tower T-102 and the top cooler H-103 is 86.34% and the temperature is -195.1°C. It then passes sequentially through the twenty-third heat exchange channel of heat exchanger LNG-104... The 21st heat exchange channel, the 18th heat exchange channel of heat exchanger LNG-103, the 10th heat exchange channel of heat exchanger LNG-102, the 6th heat exchange channel of heat exchanger LNG-101, and the 2nd heat exchange channel of heat exchanger LNG-100 lead to the crude helium storage tank. The liquid phase discharged from the first-stage helium extraction tower T-101 and the bottom reboiler H-102 passes sequentially through the 24th heat exchange channel of heat exchanger LNG-104, the throttle valve VLV-105, and the gas-liquid separator V-106. At this point, the temperature is -163.7℃, and the produced LNG product enters the LNG storage tank. The liquid nitrogen discharged from the second-stage helium extraction tower T-102 and the bottom reboiler H-104 goes to the liquid nitrogen storage tank.

[0053] The propane exiting cooler E-100 is at 20°C and 2MPa. After being depressurized by throttling valve VLV-100, its temperature drops to -5.4°C and its pressure to 0.4MPa. It then enters gas-liquid separator V-101, where it is separated into gas and liquid phases. The liquid phase at the bottom of gas-liquid separator V-101 is further divided into two parts. One part returns to heat exchanger LNG-100, providing it with cooling, and its temperature drops to 7.8°C. The other part, after being throttled by throttling valve VLV-101, reaches a temperature of -25.43°C and a pressure of 0.2MPa. It then enters gas-liquid separator V-102, where it is separated into gas and liquid phases. Similarly, the liquid phase at the bottom of cryogenic separator V-102 is also divided into two parts. One part returns to heat exchanger LNG-101, providing it with cooling, and its temperature drops to -2°C. The other part, after being throttled by throttling valve V... After throttling, the temperature of LV-102 is -38℃ and the pressure is 0.12MPa. It then enters the gas-liquid separator V-103 and is separated into gas and liquid phases. The liquid phase at the bottom of the gas-liquid separator V-103 returns to the heat exchanger LNG-102 to provide it with cooling, and its temperature is -32.5℃. After the refrigerant in the heat exchanger LNG-102 exchanges heat with it, it mixes with the gas phase at the top of the gas-liquid separator V-103. After being compressed by the compressor K-102 and mixed with the refrigerant after heat exchange with the heat exchanger LNG-101, it is compressed by the compressor K-101 and mixed with the refrigerant after heat exchange with the heat exchanger LNG-101 and the gas phase at the top of the gas-liquid separator V-102. After being compressed by the compressor K-100 and cooled by the cooler E-100 to the initial state, the propane precooling cycle is completed.

[0054] The mixed refrigerant refrigeration system contains a refrigerant mixture of 6.93% nitrogen, 42.58% methane, 29.7% ethane, and 20.79% propane. The mixed refrigerant exiting the fifteenth heat exchange channel of heat exchanger LNG-103 has a temperature of -67.86℃ and a pressure of 0.18 MPa. After three stages of compression (compressors K-105, K-104, and K-103) and three stages of cooling (coolers E-103, E-102, and E-101), the temperature is 20℃ and the pressure is 3 MPa. It then enters the third heat exchange channel of heat exchanger LNG-100. After heat exchange through the third heat exchange channel of LNG-100, the seventh heat exchange channel of LNG-101, and the eleventh heat exchange channel of LNG-102, the temperature is -21℃ and the pressure is 2.97 MPa. The gas phase at the top of the gas-liquid separator V-104 then enters the gas-liquid separator V-104. After passing through the seventeenth and twenty-second heat exchange channels of LNG-103 and LNG-104 respectively, and being throttled by the expansion valve VLV-104, the gas phase reaches a temperature of -160.8℃ and a pressure of 0.2MPa. It then returns to the twentieth and fifteenth heat exchange channels of LNG-104 to provide the required cooling capacity, finally entering the compressor K-105 inlet to complete the mixed refrigerant refrigeration cycle. The liquid phase at the bottom of the gas-liquid separator V-104 enters the LNG-103 heat exchanger, where it is further cooled. After being throttled by the expansion valve VLV-103, the liquid phase reaches a temperature of -84.5℃, and then merges with the cryogenic mixed refrigerant after heat exchange in the LNG-104 heat exchanger.

[0055] The embodiments described above are provided to help readers understand the principles of the present invention, and the scope of protection of the present invention is not limited to such specific statements and embodiments. For those skilled in the art, several combinations and modifications can be made without departing from the principles of the present invention, and these combinations and modifications are also within the scope of protection of the present invention.

Claims

1. A natural gas helium extraction process for the co-production of ethane and LNG, characterized in that: Includes an ethane recovery unit, a crude helium extraction unit, a heat exchange unit, a propane precooling system, and a mixed refrigerant refrigeration system; The ethane recovery unit includes a gas-liquid separator V-105, a throttle valve VLV-107, a compressor K-106, an expander K-107, a throttle valve VLV-108, a throttle valve VLV-109, and a demethanizer T-103; the crude helium extraction unit includes a primary helium extraction tower T-101, a top cooler H-101, a bottom reboiler H-102, a throttle valve VLV-106, a secondary helium extraction tower T-102, a top cooler H-103, and a bottom reboiler H-104; the heat exchange unit includes heat exchangers LNG-100, LNG-101, LNG-102, LNG-103, and LNG... -104, heat exchanger LNG-105; the propane precooling system includes compressor K-100, cooler E-100, throttle valve VLV-100, gas-liquid separator V-101, throttle valve VLV-101, gas-liquid separator V-102, throttle valve VLV-102, gas-liquid separator V-103, compressor K-102, compressor K-101; the mixed refrigerant refrigeration system includes compressor K-105, cooler E-103, compressor K-104, cooler E-102, compressor K-103, cooler E-101, gas-liquid separator V-104, throttle valve VLV-103, throttle valve VLV-104; The ethane recovery unit has a feed gas inlet pipe connected to heat exchanger LNG-100. Heat exchangers LNG-100, LNG-101, and LNG-102 are sequentially connected, pre-cooling and cryogenically cooling the feed gas before it enters gas-liquid separator V-105. At the top of gas-liquid separator V-105, one branch is sequentially connected to expander K-107 and demethanizer T-103, and the other branch is sequentially connected to heat exchanger LNG-105 and throttle valve VLV-109. Gas-liquid separator V-105... The bottom, throttling valve VLV-107, and demethanizer T-103 are connected in sequence; the top of demethanizer T-103, heat exchanger LNG-105, compressor K-106, and heat exchanger LNG-103 are connected in sequence, with a portion of the dry gas flowing back to the top of demethanizer T-103 via heat exchanger LNG-105 and throttling valve VLV-108; two side streams from the bottom of demethanizer T-103 enter heat exchanger LNG-102 to recover cold energy; condensate product is discharged from the bottom of demethanizer T-103; In the crude helium extraction unit, dry gas from the ethane recovery unit enters the heat exchanger LNG-103 for deep cooling before entering the primary helium extraction tower T-101. The primary helium extraction tower T-101, the top cooler H-101, the heat exchanger LNG-104, the throttle valve VLV-106, and the secondary helium extraction tower T-102 are sequentially connected for crude helium extraction. The primary helium extraction tower T-101, the bottom reboiler H-102, the heat exchanger LNG-104, and the throttle valve VLV-106 are also connected.

05. Gas-liquid separator V-106 is connected in sequence to produce LNG product, which enters the LNG storage tank; the helium gas discharged from the secondary helium extraction tower T-102 and the tower top cooler H-103 passes through heat exchangers LNG-104, LNG-103, LNG-102, LNG-101, and LNG-100 in sequence to the crude helium storage tank; liquid nitrogen is discharged from the secondary helium extraction tower T-102 and the tower bottom reboiler H-104 and goes to the liquid nitrogen storage tank. In the propane precooling system, propane, after being depressurized by the throttling valve VLV-100, enters the gas-liquid separator V-101 and is separated into gas and liquid phases. The liquid phase at the bottom of the gas-liquid separator V-101 is divided into two parts: one part returns to the heat exchanger LNG-100 to provide cooling, and the other part, after being throttled by the throttling valve VLV-101, enters the gas-liquid separator V-102 and is separated into gas and liquid phases. The liquid phase at the bottom of the gas-liquid separator V-102 is also divided into two parts: one part returns to the heat exchanger LNG-101 to provide cooling, and the other part, after being throttled by the throttling valve VLV-102, enters the gas-liquid separator V-103 and is separated into gas and liquid phases. The liquid phase is two-phase; the liquid phase at the bottom of the gas-liquid separator V-103 is returned to the heat exchanger LNG-102 to provide it with the required cooling capacity; after the heat exchanger LNG-102 exchanges heat with the refrigerant, it mixes with the gas phase at the top of the gas-liquid separator V-103. After being compressed by the compressor K-102 and mixed with the refrigerant after exchanging heat with the heat exchanger LNG-101, it is compressed by the compressor K-101 and mixed with the refrigerant after exchanging heat with the heat exchanger LNG-101 and the gas phase at the top of the gas-liquid separator V-101. After being compressed by the compressor K-100 and cooled by the cooler E-100 to the initial state, the propane precooling cycle is completed. In the mixed refrigerant refrigeration system, the mixed refrigerant sequentially passes through compressor K-105, cooler E-103, compressor K-104, cooler E-102, compressor K-103, and cooler E-101, undergoing three stages of compression and cooling before entering heat exchanger LNG-100. Heat exchangers LNG-100, LNG-101, and LNG-102, along with gas-liquid separator V-104, are sequentially connected. The gas phase at the top of gas-liquid separator V-104 sequentially passes through the heat exchanger... After being cooled by LNG-103 and LNG-104, and throttled by the expansion valve VLV-104, the LNG-103 and LNG-104 return to provide the required cooling capacity. Finally, the LNG-103 enters the inlet of the compressor K-105 to complete the mixed refrigerant refrigeration cycle. The liquid phase at the bottom of the gas-liquid separator V-104 enters the LNG-103 and is further cooled. After being throttled by the expansion valve VLV-103, the liquid phase then merges with the cryogenic mixed refrigerant that has been heated by the LNG-104.

2. The natural gas helium extraction process for co-producing ethane and LNG according to claim 1, characterized in that: The LNG-100 heat exchanger is provided with a first heat exchange channel, a second heat exchange channel, a third heat exchange channel, and a fourth heat exchange channel. The raw material gas inlet pipe is connected to the first end of the fourth heat exchange channel, and the end of the fourth heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the first heat exchange channel is connected to the top pipe of the gas-liquid separator V-101 via a pipe, and the end of the first heat exchange channel is connected to the bottom of the gas-liquid separator V-101 via a pipe; the first end of the second heat exchange channel is connected to the crude helium export pipe via a pipe, and the end of the second heat exchange channel is connected to the LNG-101 heat exchanger via a pipe; the first end of the third heat exchange channel is connected to the outlet of the cooler E-101 via a pipe, and the end of the third heat exchange channel is connected to the LNG-101 heat exchanger via a pipe.

3. The natural gas helium extraction process for co-producing ethane and LNG according to claim 2, characterized in that: The heat exchanger LNG-101 is provided with a fifth heat exchange channel, a sixth heat exchange channel, a seventh heat exchange channel, and an eighth heat exchange channel; The first end of the fifth heat exchange channel is connected to the top pipe of the gas-liquid separator V-102 via a pipe, and the last end of the fifth heat exchange channel is connected to the bottom of the gas-liquid separator V-102 via a pipe; the first end of the sixth heat exchange channel is connected to the last end of the second heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the sixth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the seventh heat exchange channel is connected to the last end of the third heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the seventh heat exchange channel is connected to the LNG-102 heat exchanger via a pipe; the first end of the eighth heat exchange channel is connected to the last end of the fourth heat exchange channel of the LNG-100 heat exchanger via a pipe, and the last end of the eighth heat exchange channel is connected to the LNG-102 heat exchanger via a pipe.

4. The natural gas helium extraction process for co-producing ethane and LNG according to claim 3, characterized in that: The heat exchanger LNG-102 is provided with a ninth heat exchange channel, a tenth heat exchange channel, an eleventh heat exchange channel, a twelfth heat exchange channel, a thirteenth heat exchange channel, and a fourteenth heat exchange channel. The first end of the ninth heat exchange channel is connected to the top pipe of the gas-liquid separator V-103 via a pipe, and the last end of the ninth heat exchange channel is connected to the bottom of the gas-liquid separator V-103 via a pipe; the first end of the tenth heat exchange channel is connected to the last end of the sixth heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the tenth heat exchange channel is connected to heat exchanger LNG-03 via a pipe; the first end of the eleventh heat exchange channel is connected to the last end of the seventh heat exchange channel of heat exchanger LNG-101 via a pipe, and the last end of the eleventh heat exchange channel is connected to the gas-liquid separator via a pipe. V-104 is connected; the first end of the twelfth heat exchange channel is connected to the end of the eighth heat exchange channel of LNG-101 via a pipeline, and the twelfth heat exchange channel is connected to the gas-liquid separator V-105 via a pipeline; the first end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the thirteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline; the first end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline, and the end of the fourteenth heat exchange channel is connected to the demethanizer T-103 via a pipeline.

5. The natural gas helium extraction process for co-producing ethane and LNG according to claim 4, characterized in that: The heat exchanger LNG-103 is equipped with a fifteenth heat exchange channel, a sixteenth heat exchange channel, a seventeenth heat exchange channel, an eighteenth heat exchange channel, and a nineteenth heat exchange channel. The first end of the fifteenth heat exchange channel is connected to the inlet of compressor K-105 via a pipeline, and the last end of the fifteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the sixteenth heat exchange channel is connected to the bottom of gas-liquid separator V-104 via a pipeline, and the last end of the sixteenth heat exchange channel is connected to throttle valve VLV-103 via a pipeline; the first end of the seventeenth heat exchange channel is connected to the top of gas-liquid separator V-104 via a pipeline, and the last end of the seventeenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the eighteenth heat exchange channel is connected to the last end of the tenth heat exchange channel of heat exchanger LNG-102 via a pipeline, and the last end of the eighteenth heat exchange channel is connected to heat exchanger LNG-104 via a pipeline; the first end of the nineteenth heat exchange channel is connected to the booster outlet of turbine expander K-106 via a pipeline, and the last end of the nineteenth heat exchange channel is connected to the first-stage helium extraction tower T-101 via a pipeline.

6. The natural gas helium extraction process for co-producing ethane and LNG according to claim 5, characterized in that: The heat exchanger LNG-104 is provided with a twentieth heat exchange channel, a twenty-first heat exchange channel, a twenty-second heat exchange channel, a twenty-third heat exchange channel, and a twenty-fourth heat exchange channel. The 20th heat exchange channel is connected via a pipeline to the end of the 15th heat exchange channel of heat exchanger LNG-103, and the end of the 20th heat exchange channel is connected via a pipeline to the throttle valve VLV-104; the 21st heat exchange channel is connected via a pipeline to the end of the 18th heat exchange channel of heat exchanger LNG-103, and the end of the 21st heat exchange channel is connected via a pipeline to the secondary helium extraction tower T-102 and the tower top cooler H-103; the 22nd heat exchange channel is connected via a pipeline to the 17th heat exchange channel of heat exchanger LNG-103. The ends of the twenty-second heat exchange channel are connected to the throttle valve VLV-104 via pipes; the beginning of the twenty-third heat exchange channel is connected to the first-stage helium extraction tower T-101 and the top cooler H-101 via pipes, and the end of the twenty-third heat exchange channel is connected to the throttle valve VLV-106 via pipes; the beginning of the twenty-fourth heat exchange channel is connected to the first-stage helium extraction tower T-101 and the bottom reboiler H-102 via pipes, and the end of the twenty-fourth heat exchange channel is connected to the throttle valve VLV-105 via pipes.

7. The natural gas helium extraction process for co-producing ethane and LNG according to claim 6, characterized in that: The LNG-105 heat exchanger is equipped with a 25th heat exchange channel, a 26th heat exchange channel, and a 27th heat exchange channel. The first end of the 25th heat exchange channel is connected to the inlet of compressor K-106 via a pipeline, and the last end of the 25th heat exchange channel is connected to the top of demethanizer T-103 via a pipeline; the first end of the 26th heat exchange channel is connected to the return dry gas pipeline via a pipeline, and the last end of the 26th heat exchange channel is connected to throttle valve VLV-108 via a pipeline; the first end of the 27th heat exchange channel is connected to the top of gas-liquid separator V-105 via a pipeline, and the last end of the 27th heat exchange channel is connected to throttle valve VLV-109 via a pipeline.

8. A natural gas helium extraction process for co-producing ethane and LNG according to any one of claims 1-7, characterized in that: The propane precooling system provides cooling capacity for heat exchangers LNG-100, LNG-101, and LNG-102, using propane as the circulating refrigerant; the mixed refrigerant refrigeration system provides cooling capacity for heat exchangers LNG-103 and LNG-104, using a mixed refrigerant composed of nitrogen, methane, ethane, and propane as the circulating refrigerant.

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