A system and method for extracting helium from natural gas

Abstract

This invention discloses a system and method for extracting helium from natural gas. The system includes an air expander, a cooler, a cold box, and a helium purification system. The cold box includes a main heat exchanger, an air-liquid separator, and an LNG-liquid separator. The helium purification system includes an oxygen-addition and hydrogen-removal reactor, a helium purification system cooler, a helium purifier, a circulating compressor, a booster compressor, and a Dewar flask. The Dewar flask contains a heat exchanger, a gas-liquid separator, and an adsorber. This invention features a reasonable process design, simple equipment, and easy operation, achieving a helium extraction rate of up to 98%. By delivering methane to users in the form of LNG and using low-temperature adsorption to produce pure helium, the economic value of the product is improved.

Description

Technical Field

[0001] This invention relates to the field of helium extraction technology, and more particularly to a system and method for extracting helium from natural gas. Background Technology

[0002] Helium is a strategic material with crucial applications in aerospace, defense, medicine, and leak detection. Helium is an inert gas, with a concentration of only 5.24 × 10⁻⁶ in air. -6 Helium is a non-condensable gas in the distillation column of an air separation unit, accumulating in a gaseous state at the top of the main condenser and in the nitrogen reflux liquid. It is difficult to separate. Helium is mainly found in natural gas, and extracting helium from natural gas is the primary source of helium production. However, the helium content in Chinese natural gas is extremely low, while the flash gas (BOG) of liquefied natural gas or other chemical tail gases using natural gas as feedstock is rich in helium, making extraction from it more economically valuable. However, most BOG gas contains hydrogen, and separating helium and hydrogen using cryogenic methods is energy-intensive, reducing the economic value of helium. Direct catalytic methods would result in excessively high temperatures, which the equipment cannot withstand; after helium extraction from BOG, the main component is natural gas, and the usual practice is to directly return the gas to the pipeline network, requiring additional pressurization and resulting in high energy consumption.

[0003] CN202010819902.3 discloses a system for extracting helium from natural gas, including an air expander, a cooler, a cold box, and a helium purification system. The cold box includes an E1 main heat exchanger, a C1 distillation column, a K1 air reboiler and a K2 LNG reboiler located at the bottom of the C1 distillation column, an E2 subcooler, and a K3 condenser-evaporator. The helium purification system includes an oxygen-adding and hydrogen-removing reactor, a cooler, a helium purifier, a compressor, and a Dewar flask. The Dewar flask contains a heat exchanger, a gas-liquid separator, and an adsorber. This invention patent uses a distillation column within the cold box and incorporates multiple heat exchangers including reboilers and condensers-evaporators, resulting in a complex process, poor operability, and high equipment investment. Returning methane in gaseous form is less economical compared to returning it in LNG form. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a system and method for extracting helium from natural gas.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of this invention is to provide a system for extracting helium from natural gas, comprising an air expander, a cooler, a cold box, and a helium purification system; the cold box includes a main heat exchanger, an air-liquid separator, and an LNG-liquid separator; the helium purification system includes an oxygenation and hydrogen removal reactor, a helium purification system cooler, a helium purifier, a circulating compressor, a booster compressor, and a Dewar flask, wherein the Dewar flask is equipped with a heat exchanger, a gas-liquid separator, and an adsorber;

[0007] The pipe connection sequence is as follows:

[0008] The air expander's booster end, cooler, and top air inlet of the main heat exchanger are connected in sequence. The lower middle air outlet of the main heat exchanger is connected to the expansion end of the air expander via a pipeline, and then connected to the cold end of the main heat exchanger. The cold end outlet of the main heat exchanger is connected to an air-liquid separator, and the gas phase outlet of the air-liquid separator is connected to the cold end of the main heat exchanger. The natural gas feedstock pipeline is connected to the LNG gas-liquid separator after passing through the main heat exchanger. The gas phase outlet of the LNG gas-liquid separator is connected to the cold end of the main heat exchanger, and the light component outlet of the main heat exchanger is connected to the oxygenation and hydrogen removal reactor.

[0009] The oxygenation and hydrogen removal reactor is sequentially connected to the helium purification system cooler, helium purifier, booster compressor, crude helium inlet of the heat exchanger inside the Dewar flask, and gas-liquid separator. The bottom of the gas-liquid separator has a liquid outlet, and the helium outlet at the top of the gas-liquid separator is sequentially connected to the adsorber, the heat exchanger, and then to the Dewar flask and the pure helium pipeline. The connecting pipeline between the helium purifier and the Dewar flask is connected to the connecting pipeline between the main heat exchanger and the oxygenation and hydrogen removal reactor via a branch pipeline equipped with the circulating compressor.

[0010] The connection is a pipeline connection.

[0011] Furthermore, the Dewar flask is also connected to a liquid discharge line, and a vacuum pump is installed on the liquid discharge line.

[0012] Furthermore, the bottom liquid phase outlet of the air-liquid separator is connected to the Dewar flask via a pipeline.

[0013] Furthermore, the bottom liquid phase outlet of the LNG gas-liquid separator is connected to the storage tank via a pipeline.

[0014] A second aspect of the present invention is to provide a method for extracting helium from natural gas using the above-described system, comprising the following steps:

[0015] Step 1: After compression, pre-cooling and purification to remove water and carbon dioxide, the air is pressurized at the booster end of an air expander, then cooled in a cooler, and then sent to the main heat exchanger of the cold box for further cooling. A portion of the air is drawn from the lower part of the main heat exchanger and sent to the expansion end of the expander, where it expands to a lower pressure. After the air temperature drops, it is sent back to the cold end of the main heat exchanger to serve as a cold source for cooling the fluid entering the cold box. The air itself is reheated and discharged from the cold box or recycled. Another portion of the air in the lower part of the main heat exchanger is liquefied at the cold end and then sent to an air-liquid separator. After gas-liquid separation, the gas is sent out of the cold box after heat exchange, and the liquid is drawn out of the cold box and sent to the Dewar flask as a cold source.

[0016] Step 2: The natural gas feedstock enters the cold box, first enters the main heat exchanger to be cooled to a partially liquid state, and then enters the LNG gas-liquid separator for separation. The liquid is directly extracted from the cold box and sent to the storage tank, while the gas passes through the main heat exchanger to recover its cooling capacity. After being reheated, it is sent to the oxygenation and hydrogen removal reactor.

[0017] Step 3: Hydrogen is removed by reaction in an oxygen-adding and hydrogen-removing reactor. After cooling, water is removed using a helium purifier to obtain crude helium. The crude helium is pressurized by a booster compressor and sent into a Dewar flask. A heat exchanger inside the Dewar flask cools the crude helium, which then enters a gas-liquid separator immersed in liquid air. The liquid is discharged from the bottom, and the discharged gas is mostly helium. Small amounts of oxygen, nitrogen, and argon are adsorbed off by an adsorber. The resulting pure helium is then sent out of the Dewar flask after the heat exchanger recovers the cold energy.

[0018] Furthermore, it also includes: when the hydrogen concentration in the gas entering the oxygenation and hydrogen removal reactor is too high, a portion of the gas exiting the helium purifier is sent to the oxygenation and hydrogen removal reactor via a circulating compressor to dilute the hydrogen in the gas.

[0019] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0020] The present invention features a reasonable process design, simple equipment, and easy operation, achieving a helium extraction rate of up to 98%. Methane is delivered to users in the form of LNG, and pure helium is produced using low-temperature adsorption, thereby improving the economic value of the product. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system for extracting helium from natural gas according to the present invention;

[0022] The reference numerals in the attached figures are:

[0023] 1-Air expander, 2-Cooler, 3-Cold box, 4-Main heat exchanger, 5-Expansion end of air expander, 6-Oxygen addition and hydrogen removal reactor, 7-Helium purification system cooler, 8-Helium purifier, 9-Circulating compressor, 10-Boosting compressor, 11-Dewar flask, 12-Heat exchanger, 13-Gas-liquid separator, 14-Adsorber, 15-Vacuum pump, 16-Air-gas-liquid separator, 17-LNG-gas-liquid separator. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0025] refer to Figure 1 The present invention provides a system for extracting helium from natural gas, comprising an air expander 1, a cooler 2, a cold box 3, and a helium purification system; the cold box includes a main heat exchanger 4 (E1), an air-liquid separator 16, and an LNG-liquid separator 17; the helium purification system includes an oxygenation and hydrogen removal reactor 6, a helium purification system cooler 7, a helium purifier 8, a circulating compressor 9, a booster compressor 10, and a Dewar flask 11, wherein a heat exchanger 12, a gas-liquid separator 13, and an adsorber 14 are provided inside the Dewar flask 11;

[0026] The pipe connection sequence is as follows:

[0027] The air inlet of the air expander 1, the cooler 2, and the top air inlet of the main heat exchanger 4 are connected in sequence. The air outlet of the middle and lower part of the main heat exchanger 4 is connected to the expansion end 5 of the air expander through a pipeline. After passing through the expansion end of the air expander, it is connected to the cold end of the main heat exchanger 1. The cold end outlet of the main heat exchanger 1 is connected to the air-liquid separator 16. The gas phase outlet of the air-liquid separator 16 is connected to the cold end of the main heat exchanger 1. The natural gas feedstock pipeline is connected to the LNG-liquid separator 17 after passing through the main heat exchanger 1. The gas phase outlet of the LNG-liquid separator 17 is connected to the cold end of the main heat exchanger 1. The light component outlet of the main heat exchanger 1 is connected to the oxygenation and hydrogen removal reactor 6.

[0028] The oxygen-adding and hydrogen-removing reactor 6 is sequentially connected to the helium purification system cooler 7, helium purifier 8, booster compressor 10, the crude helium inlet of the heat exchanger 12 inside the Dewar flask 11, and the gas-liquid separator 13. The bottom of the gas-liquid separator 13 is provided with a liquid outlet. The helium outlet at the top of the gas-liquid separator 13 is sequentially connected to the adsorber 14, the heat exchanger 12, and then to the Dewar flask 11, which is connected to the pure helium pipeline. The connecting pipeline between the helium purifier 8 and the Dewar flask 11 is connected to the connecting pipeline between the main heat exchanger 4 and the oxygen-adding and hydrogen-removing reactor 6 through a branch pipeline equipped with a circulating compressor 9.

[0029] The connection is a pipe connection.

[0030] The Dewar flask 11 is also connected to a liquid discharge line, on which a vacuum pump 15 is installed; the bottom liquid phase outlet of the air-liquid separator 16 is connected to the Dewar flask 11 via a pipeline; the bottom liquid phase outlet of the LNG gas-liquid separator 17 is connected to the storage tank via a pipeline. Figure 1 (Not shown in the image)

[0031] The present invention also provides a method for extracting helium from natural gas using the above-described system, comprising the following steps:

[0032] Step 1: The air is compressed, pre-cooled and purified (the compression and pre-cooling purification of air are conventional techniques in current air separation, and will not be described again in this invention). After removing water and carbon dioxide, the air is pressurized at the pressurization end of the air expander 1, then cooled in the cooler 2, and then sent to the main heat exchanger 4 of the cold box 3 for further cooling. A portion of the air is drawn from the lower part of the main heat exchanger 4 and sent to the expansion end 5 of the expander to expand to a lower pressure. After the air temperature drops, it is sent back to the cold end of the main heat exchanger 4 to serve as a cold source to cool the fluid entering the cold box 3. The air itself is reheated and discharged from the cold box 3 or recycled. Another portion of the air in the lower part of the main heat exchanger 4 is liquefied at the cold end of the main heat exchanger and then sent to the air-liquid separator 16. After gas-liquid separation, the gas is sent out of the cold box 3 after heat exchange, and the liquid is drawn out of the cold box and sent to the Dewar flask 11 as a cold source to provide a low-temperature environment for the low-temperature adsorption of helium.

[0033] Step 2: The natural gas feedstock (natural gas, BOG gas, or chemical feedstock) enters the cold box 3. First, it enters the main heat exchanger 4 and is cooled to a partially liquid state. Then, it enters the LNG gas-liquid separator 17 for separation. The liquid (mainly methane, nitrogen, and very small amounts of helium and hydrogen) is directly extracted from the cold box 3 and sent to the storage tank. The light component gas (mainly hydrogen, helium, nitrogen, and methane) recovers its cold energy through the main heat exchanger 4, is reheated, and then sent to the oxygenation and hydrogen removal reactor 6.

[0034] The LNG gas-liquid separator utilizes the physical property that helium and hydrogen have a large boiling point difference with nitrogen and methane. At a relatively low temperature, most of the helium and hydrogen can be extracted. The equipment is simple and easy to operate.

[0035] Step 3: Most of the helium in the raw material is in the light component gas. The light component gas enters the oxygen-adding and hydrogen-removing reactor 6 to react and remove hydrogen. After cooling, water is removed by the helium purifier 8 to obtain crude helium. The crude helium is pressurized by the booster compressor 10 and sent to the Dewar flask 11. The heat exchanger 12 installed in the Dewar flask 11 cools the crude helium and then enters the gas-liquid separator 13 immersed in liquid air. The liquid is discharged from the bottom, and most of the discharged gas is helium. A small amount of oxygen, nitrogen, and argon are adsorbed off by the adsorber 14. The obtained pure helium is sent out of the Dewar flask 11 after the heat exchanger 12 recovers the cold energy.

[0036] In the oxygen-removing furnace 6, hydrogen reacts with newly added oxygen to produce water, releasing heat (temperature rise). The water is then cooled by the helium purification system cooler 7 before entering the helium purifier 8 for dehydration, yielding crude helium. If the hydrogen content is high, removing hydrogen in one step requires more oxygen, resulting in a large exothermic reaction and a very high post-reaction gas temperature, increasing the difficulty of container design and manufacturing, and operational hazards. To address the various problems caused by excessively high hydrogen concentrations, a circulating compressor 9 is installed. The crude helium, after hydrogen removal, is pressurized by the circulating compressor 9 and added before the hydrogen removal furnace. This dilutes the hydrogen in the light component gas and controls the reaction temperature.

[0037] Example 1

[0038] The air is compressed, pre-cooled, and purified (air compression and pre-cooling purification are standard techniques in current air separation processes and will not be described further in this method). After water and dioxide are removed in the air separation tower, the air passes through the GA-101 line (pressure: 1.2 MPa, absolute pressure, the same below; temperature: 20℃; composition: clean air; flow rate: 6000 Nm³). 3 The air is pressurized by the air expander 1, passes through GA-102 (pressure: 1.82MPa; temperature: 80℃, composition: clean air), enters cooler 2 for cooling, and then passes through GA-103 (pressure: 1.85MPa; temperature: 40℃, composition: clean air) before entering cold box 3. The air first enters the main heat exchanger 4 for cooling, and a portion of the air is drawn from the lower part of the main heat exchanger 4, passing through GA-201 (pressure: 1.81MPa; temperature: -108℃, composition: clean air, flow rate: 5880Nm³). 3 The air is fed into the expansion end 5 of the air expander and expanded. It is then sent back to the cold end of the main heat exchanger 4 (E1) via GA-202 (pressure: 0.13MPa; temperature: -185℃, composition: clean air) to serve as a cold source to cool the fluid entering the cold box 3. The fluid itself is reheated and discharged from the cold box 3 or recycled.

[0039] Another portion of the air is liquefied at the cold end of the E1 main heat exchanger 4 to LA-104 (pressure: 1.8MPa; temperature: -171℃, state: liquid, composition: clean air, flow rate: 120Nm). 3 / h) After being throttled and partially vaporized by throttle valve V1, LA-105 (pressure: 0.3MPa; temperature: -183℃, composition: clean air, flow rate: 120Nm) 3 The gas is then separated from the liquid by the T01 air-liquid separator 16 (pressure: 0.3MPa; temperature: -183℃; state: gas; composition: clean air; flow rate: 20Nm³ / h). 3The gas section ( / h) enters the expansion pipe GA-202, is reheated by the E1 main heat exchanger 4, and then exits the cold box 3. The liquid section at the bottom of the T01 air-liquid separator 16, LA-131 (pressure: 0.3MPa; temperature: -183℃, state: liquid, composition: clean air, flow rate: 100Nm³ / h), is composed of clean air. 3 / h) Extract 3 cold boxes and send them to Dewar flask 11 as a cold source to provide a low-temperature environment for the low-temperature adsorption of helium.

[0040] Pressurized natural gas feedstock (natural gas, BOG gas, or chemical feedstock) GNG-301 (Pressure: 0.55 MPa; Temperature: 20℃; State: Gas; Composition: He 2.15%; Hydrogen 0.62%; Nitrogen 7.7%; Methane 89.5%; Flow rate: 625 Nm³) 3 The gas enters the cold box 3 ( / h) and first enters the E1 main heat exchanger 4 to be cooled by GNG-302 (pressure: 0.535MPa; temperature: -180℃, state: gas, composition: He 2.15%; hydrogen 0.62%; nitrogen 7.7%; methane 89.5%, flow rate: 625Nm). 3 The gas (at a rate of 1 h) enters the T02LNG gas-liquid separator 17 for separation. The gaseous portion is separated in pipeline GHe-101 (composition: He 65.8%; hydrogen 17.7%; nitrogen 13.5%; methane 3%, flow rate: 20.3 Nm³). 3 / h); Liquid section, pipeline LNG-01 (composition: He 0.02%; hydrogen 0.046%; nitrogen 7.5%; methane 92.4%, flow rate: 604.7 Nm³ / h); 3 (h) The gas is directly extracted from the cold box and sent to the storage tank. Utilizing the large boiling point difference between helium and hydrogen and nitrogen and methane, a gas-liquid separator can extract most of the helium and hydrogen at relatively low temperatures. The equipment is simple and easy to operate.

[0041] LNG gas-liquid separation: the light components of LNG 17 are cooled by the E1 main heat exchanger 4, and then sent out of the cold box 3 after being reheated to room temperature. GHe-402 (Pressure: 0.489 MPa; Temperature: 35℃; Composition: He 65.8%; Hydrogen 17.7%; Nitrogen 13.5%; Methane 3%; Flow rate: 20.3 Nm³) 3 / h)

[0042] After the light component gas GHe-102 is extracted from the cold box, oxygen is added (flow rate: ~10 Nm³). 3 In the oxygen-removing reactor 6 (with a slight excess of oxygen per hour), hydrogen reacts with newly added oxygen to produce water, releasing heat (heating). The reaction equation is: 2H₂ + O₂ = 2H₂O.

[0043] After being cooled by cooler 7 in the helium purification system, it enters helium purifier 8 for dehydration, yielding crude helium, GHe-106 (pressure: 0.45 MPa; temperature: 40℃, composition: He 54.6%; hydrogen 0%; nitrogen 43.2%; methane 3%; oxygen 0.6%, flow rate: 94.4 Nm³). 3 / h). Because GHe-102 has a high hydrogen content of 17.7%, removing hydrogen in a single step requires a large amount of oxygen, resulting in a high exothermic reaction and a post-reaction gas temperature increase of over 1000℃. This increases the difficulty of container design and manufacturing, as well as operational hazards. To reduce the hydrogen concentration during the reaction, a circulating compressor 9 is installed. A portion of the crude helium gas GHe-106 after hydrogen removal is extracted into GHe-501 (flow rate: 70 Nm³). 3 The hydrogen gas is pressurized to 0.7 MPa by the circulating compressor 9 and then added to the GHe-102 gas before the oxygenation and hydrogen removal reactor 6. The hydrogen gas is diluted to control the reaction temperature at around 450℃.

[0044] After the hydrogen has been removed, the crude helium gas is pressurized to 3.5 MPa by a booster compressor 10, and then processed by GHe-107 (pressure: 3.5 MPa; temperature: 40℃, composition: He 54.6%; hydrogen 0%; nitrogen 43.2%; methane 3%; oxygen 0.6%, flow rate: 24.4 Nm³). 3 / h); enters Dewar flask 11. A heat exchanger 12 is installed inside Dewar flask 11 to cool the crude helium to -200℃. The crude helium GHe-108 exiting the heat exchanger 12 enters a gas-liquid separator 13 immersed in liquid air. Most of the nitrogen, oxygen, argon, etc., are discharged from the bottom of the gas-liquid separator 13 in liquid form. The gas discharged from the gas-liquid separator 13 is mostly helium, GHe-109 (pressure: 3.5MPa; temperature: -200℃, composition: He 98.1%; nitrogen 1.85%; trace amounts of methane, oxygen, etc., flow rate: 13.5Nm). 3 The crude helium gas ( / h) is adsorbed by adsorber 14 to remove oxygen, nitrogen, argon, and neon. Pure helium then passes through adsorber 14, followed by heat exchanger 12 to recover its cooling capacity, and is then discharged from Dewar flask 11. GHe-111 (Pressure: 3.1 MPa; Temperature: -50℃; Composition: He 99.999%; Flow rate: 13.2 Nm³) 3 ( / h) can be directly piped to the user or used to fill the compressor bottle.

[0045] In the liquid air environment, the Dewar flask 11 is evacuated using a vacuum pump 15 to maintain a pressure of approximately 20 kPa. At this pressure, the boiling point of liquid air is -200°C. The adsorbent in the adsorber 14 has a higher efficiency.

[0046] In this embodiment, the helium extraction rate is 98%.

[0047] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the content and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for extracting helium from natural gas, characterized in that, It includes an air expander, a cooler, a cold box, and a helium purification system; the cold box includes a main heat exchanger, an air-liquid separator, and an LNG-liquid separator; the helium purification system includes an oxygen addition and hydrogen removal reactor, a helium purification system cooler, a helium purifier, a circulating compressor, a booster compressor, and a Dewar flask, wherein the Dewar flask is equipped with a heat exchanger, a gas-liquid separator, and an adsorber; The pipe connection sequence is as follows: The air expander's booster end, cooler, and top air inlet of the main heat exchanger are connected in sequence. The lower middle air outlet of the main heat exchanger is connected to the expansion end of the air expander via a pipeline, and then connected to the cold end of the main heat exchanger. The cold end outlet of the main heat exchanger is connected to an air-liquid separator, and the gas phase outlet of the air-liquid separator is connected to the cold end of the main heat exchanger. The natural gas feedstock pipeline is connected to the LNG gas-liquid separator after passing through the main heat exchanger. The gas phase outlet of the LNG gas-liquid separator is connected to the cold end of the main heat exchanger, and the light component outlet of the main heat exchanger is connected to the oxygenation and hydrogen removal reactor. The oxygenation and hydrogen removal reactor is sequentially connected to the helium purification system cooler, helium purifier, booster compressor, crude helium inlet of the heat exchanger inside the Dewar flask, and gas-liquid separator. The bottom of the gas-liquid separator has a liquid outlet, and the helium outlet at the top of the gas-liquid separator is sequentially connected to the adsorber, the heat exchanger, and then to the Dewar flask and the pure helium pipeline. The connecting pipeline between the helium purifier and the Dewar flask is connected to the connecting pipeline between the main heat exchanger and the oxygenation and hydrogen removal reactor via a branch pipeline equipped with the circulating compressor. The connection is a pipeline connection; The method for extracting helium from natural gas using the system described above includes the following steps: Step 1: After compression, pre-cooling and purification to remove water and carbon dioxide, the air is pressurized at the booster end of an air expander, then cooled in a cooler, and then sent to the main heat exchanger of the cold box for further cooling. A portion of the air is drawn from the lower part of the main heat exchanger and sent to the expansion end of the expander, where it expands to a lower pressure. After the air temperature drops, it is sent back to the cold end of the main heat exchanger to serve as a cold source for cooling the fluid entering the cold box. The air itself is reheated and discharged from the cold box or recycled. Another portion of the air in the lower part of the main heat exchanger is liquefied at the cold end and then sent to an air-liquid separator. After gas-liquid separation, the gas is sent out of the cold box after heat exchange, and the liquid is drawn out of the cold box and sent to the Dewar flask as a cold source. Step 2: The natural gas feedstock enters the cold box, first enters the main heat exchanger to be cooled to a partially liquid state, and then enters the LNG gas-liquid separator for separation. The liquid is directly extracted from the cold box and sent to the storage tank, while the gas passes through the main heat exchanger to recover its cooling capacity. After being reheated, it is sent to the oxygenation and hydrogen removal reactor. Step 3: Hydrogen is removed by reaction in an oxygen-adding and hydrogen-removing reactor. After cooling, water is removed using a helium purifier to obtain crude helium. The crude helium is pressurized by a booster compressor and sent into a Dewar flask. A heat exchanger inside the Dewar flask cools the crude helium, which then enters a gas-liquid separator immersed in liquid air. The liquid is discharged from the bottom, and the discharged gas is mostly helium. Small amounts of oxygen, nitrogen, and argon are adsorbed off by an adsorber. The resulting pure helium is then sent out of the Dewar flask after the heat exchanger recovers the cold energy.

2. The system according to claim 1, characterized in that, The Dewar flask is also connected to a liquid discharge line, which is equipped with a vacuum pump.

3. The system according to claim 1, characterized in that, The bottom liquid phase outlet of the air-liquid separator is connected to the Dewar flask via a pipeline.

4. The system according to claim 1, characterized in that, The bottom liquid phase outlet of the LNG gas-liquid separator is connected to the storage tank via a pipeline.

5. The system according to claim 1, characterized in that, Also includes: When the hydrogen concentration in the gas entering the oxygenation and dehydrogenation reactor is too high, a portion of the gas exiting the helium purifier is sent to the oxygenation and dehydrogenation reactor via a circulating compressor to dilute the hydrogen in the gas.

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