Apparatus and process for obtaining high purity helium directly from natural gas

Abstract

The present application relates to a kind of equipment and process for obtaining high-purity helium directly from natural gas, and the equipment for obtaining high-purity helium directly from natural gas includes precision oil filter, membrane separation system, acid gas removal unit, fine desulfurization unit, dehydrogenation unit, re-purification system and low-temperature impurity removal unit.The present application is mainly used to solve the helium purification in helium-poor, ultra-lean helium natural gas according to the current situation of domestic resources, and adopts multi-stage membrane separation + low-temperature adsorption process to realize the extraction of helium-poor natural gas and obtain high-purity helium or liquid helium, which can directly extract helium from the purified natural gas of helium-poor, ultra-lean helium gas field (0.03-0.1% He) and purify it into high-purity helium (99.999%);The present application sets up a purification unit before low-temperature purification to completely remove CO2 and H2O, and uses non-permeable tail gas for regeneration, without N2 impurities entering the process gas, by reasonably arranging the positions of COS hydrolysis and dehydrogenation reaction to avoid the "cold and hot disease" problem of process flow, which can completely remove impurities Ar, Ne and the like to effectively ensure the purity of helium.

Description

Technical Field

[0001] This invention relates to the field of helium production technology, specifically to an equipment and process for directly obtaining high-purity helium from natural gas. Background Technology

[0002] Traditional cryogenic extraction technology for helium is used in helium-poor or even extremely poor helium fields, which are common in China. However, the cost per unit product is high and it has no industrial application value.

[0003] Chinese patents CN214087729U ("A System for Extracting and Purifying Helium from Natural Gas at Ambient Temperature") and CN215113528U ("A Device for Extracting Helium from Natural Gas to Produce Liquid Helium") disclose technologies for extracting helium from natural gas. CN214087729U suffers from several drawbacks: first, it relies solely on pressure swing adsorption (PSA) as the final purification method, resulting in incomplete removal of impurities such as CH4, N2, Ar, and especially Ne. These impurities accumulate with the circulating gas during the production process, leading to substandard helium purity; second, it neglects drying and dehydration, making it difficult to guarantee the product dew point; and third, it fails to address sulfur removal, hindering the long-term operation of the dehydrogenation unit. CN215113528U uses MDEA for decarbonization, but it fails to consider the impact of amine volatilization or entrainment on the tolerance and performance of subsequent separation membranes. Furthermore, the high back pressure downstream of the membrane separator and the small pressure differential during membrane separation operation result in poor separation performance, significantly increased investment in membrane equipment, and an uneconomical technical approach.

[0004] The existing technologies for extracting helium from natural gas generally suffer from the following problems:

[0005] 1) Natural gas from domestic gas fields generally contains sulfur; even processed export products typically have a sulfur content of 20–100 mg / cm³. 3 Furthermore, organic sulfur is the main component, and none of the existing publicly available technologies have considered sulfur removal solutions. Neither PSA nor MDEA can effectively remove organic sulfur, making it impossible for the dehydrogenation unit to operate for a long time.

[0006] 2) Existing technologies do not consider the operating conditions for catalytic dehydrogenation and decarbonization. Dehydrogenation at room temperature cannot guarantee the conversion rate of hydrogen, resulting in substandard helium purity.

[0007] 3) The oil and gas industry mostly uses oil-lubricated piston compressors. Natural gas products contain trace amounts of lubricating oil, which can affect the membrane separation effect and even the lifespan of the membrane in the long run. Existing technology requires pre-membrane filtration treatment facilities.

[0008] 4) Existing technologies do not consider the source of dehydrogenated oxygen. Trace amounts of impurities such as N2 and Ar in oxygen may adversely affect the purity of the product.

[0009] 5) Although the existing technology takes into account the dehydration process, it does not clearly specify the regeneration method of the drying system and the source of the regeneration gas.

[0010] Therefore, there is still considerable room for improvement in the technology for obtaining a single helium product based on the current domestic natural gas conditions. Summary of the Invention

[0011] The first technical problem to be solved by this invention is to provide an equipment and process for directly extracting helium from pipeline natural gas with low or extra-low helium content and purifying it into high-purity helium (99.999%) and producing liquid helium, based on the current domestic resource situation.

[0012] The second technical problem to be solved by this invention is to provide a pre-membrane filtration device to address the impact of residual lubricating grease from the compressor on the long-term operation of membrane separation, in light of the current state of the prior art.

[0013] The third technical problem to be solved by the present invention is to provide a method for removing acidic gases in light of the current state of the prior art, so as to avoid the adverse effects of process gases introduced by the absorbed solvent on the separation membrane.

[0014] The fourth technical problem to be solved by this invention is to provide a method for effectively removing organic and inorganic sulfur through a combination of a COS medium-temperature hydrolysis tower and a fine desulfurization tower, in light of the current state of the technology, thereby ensuring the long-term stable operation of the catalytic dehydrogenation unit.

[0015] The fifth technical problem to be solved by this invention is to address the current state of the technology by proposing specific locations for oxygen supplementation required for hydrogenation and organic sulfur oxidation, and by using water electrolysis to obtain high-purity oxygen to reduce the accumulation of impurities, thereby effectively ensuring the purity of helium.

[0016] The sixth technical problem to be solved by this invention is to address the current state of the prior art by using TSA for thorough drying and utilizing exhaust gas as a regeneration gas source to reduce the loss of useful gas.

[0017] The seventh technical problem to be solved by this invention is to address the current state of the technology by proposing to use a compressor in stages to meet the optimal operating temperature requirements for COS hydrolysis, fine desulfurization, and dehydrogenation reactions, thereby avoiding the "cold and hot disease" problem in the process flow and making energy utilization more rational.

[0018] The present invention also provides a process for directly obtaining high-purity helium from natural gas.

[0019] The technical solution adopted by the present invention to solve at least one of the above-mentioned technical problems is as follows:

[0020] An apparatus for directly obtaining high-purity helium from natural gas, comprising:

[0021] The precision oil filter is equipped with an inlet for the input of lean helium-containing sulfur natural gas, used to remove suspended oil droplets from the natural gas;

[0022] A membrane separation system, located downstream of the precision oil filter, includes at least two sets of membrane separators connected in series or in parallel, used to perform permeation separation on the material to obtain non-permeable gas sent to the natural gas tail gas pipeline and permeable gas enriched with helium.

[0023] An acid gas removal unit is connected to the membrane separation system and is used to remove CO2 and H2S from the process gas and to remove the volatilized amine liquid.

[0024] The fine desulfurization unit is connected to the membrane separation system and located downstream of the acid gas removal unit, and is used to remove sulfur-containing substances from the process gas.

[0025] The dehydrogenation unit, connected to the membrane separation system and located downstream of the fine desulfurization unit, is used to remove residual H2 from the process gas.

[0026] A re-purification system, located downstream of the membrane separation system and the dehydrogenation unit, is used to remove at least one of CO2, H2O, and sulfides contained in the process gas; and

[0027] A low-temperature impurity removal unit is located downstream of the re-purification system and is used to remove at least one of CH4, N2, Ar, O2, and Ne contained in the process gas.

[0028] Preferably, the acid gas removal unit is connected in series between two adjacent membrane separators, and includes an amine scrubbing tower and an amine scrubbing tower connected in series along the gas flow direction. The amine scrubbing tower is used to remove a large amount of CO2 and H2S from the process gas, and the amine scrubbing tower is used to remove entrained amine liquid from the process gas. Preferably, when the raw material processing scale is small and the CO2 content is high, the acid gas removal unit can be replaced by a VPSA process.

[0029] Preferably, the fine desulfurization unit is connected in series between two adjacent membrane separators, and includes a COS intermediate-temperature hydrolysis tower, a water cooler, and a fine desulfurization tower connected in series. The COS intermediate-temperature hydrolysis tower is used to convert COS into H2S, the water cooler is used to cool the process gas, and the fine desulfurization tower is used to remove all sulfides. Preferably, the desulfurization unit can use multiple stages of COS hydrolysis towers and fine desulfurization units connected in series or in parallel as needed.

[0030] Preferably, it also includes an electrolytic water device for providing high-purity oxygen, the oxygen output end of which is connected to the inlet of the fine desulfurization tower to provide the required oxygen for the organic sulfur oxidation and dehydrogenation unit of the fine desulfurization tower.

[0031] Preferably, the dehydrogenation unit is connected in series between two adjacent membrane separators, including an upstream catalytic dehydrogenation reactor and a downstream dehydrogenation cooler. The catalytic dehydrogenation reactor is used to remove residual H2 from the process gas, and the dehydrogenation cooler is used to cool the process gas after residual H2 removal, preparing it for entry into the downstream membrane separator. Preferably, multi-stage dehydrogenation reactors can be used in series or in parallel combination as needed.

[0032] Preferably, the membrane separation system includes a #1 membrane separator, a #2 membrane separator, and a #3 membrane separator connected in series. A #1 compressor for pressurizing the process gas is installed between the #1 membrane separator and the #2 membrane separator. A #2 compressor and a #2 booster compressor for pressurizing the process gas are installed between the #2 membrane separator and the #3 membrane separator. A #3 compressor for pressurizing the process gas is installed between the #3 membrane separator and the repurification system.

[0033] Preferably, the acid gas removal unit is located between membrane separator #1 and membrane separator #2, and downstream of compressor #1; the fine desulfurization unit is located between membrane separator #2 and membrane separator #3, and between compressor #2 and booster compressor #2; the dehydrogenation unit is located between membrane separator #2 and membrane separator #3, and downstream of booster compressor #2. Preferably, for optimal performance, neither compressor #2 nor booster compressor #2 has an aftercooler.

[0034] Preferably, the top of the No. 1 membrane separator is connected to a first pipe that connects its non-permeable gas side to the natural gas pipeline network, the top of the No. 2 membrane separator is connected to a second pipe that connects its non-permeable gas side to the first pipe, and the top of the No. 3 membrane separator is connected to a third pipe that connects its non-permeable gas side to the pipeline between the No. 1 compressor and the inlet of the No. 2 membrane separator.

[0035] Preferably, the re-purification system is a TSA purification system, which includes an adsorption unit and a regeneration unit. The adsorption unit is filled with an adsorbent for adsorbing CO2, water, heavy hydrocarbons, and some sulfides. The regeneration unit includes a fourth pipe and a fifth pipe. The fourth pipe is connected near the inlet of the first pipe to the top inlet of the TSA purification system, and is used to introduce some non-permeable gas from the first pipe into the TSA purification system to purge impurities adsorbed in the adsorbent. The fifth pipe is connected between the top outlet of the TSA purification system and the second pipe.

[0036] In this invention, the cryogenic impurity removal unit can also be a PSA process device. The PSA tail gas can be recycled to the inlet of compressor #1 or compressor #2 to improve helium yield. In this case, the TSA purification system can be replaced by a refrigerated dryer to remove moisture from the system. The non-permeable gas from membrane separator #3 is directly returned to the inlet of membrane separator #2, or it can be returned to compressor #1 to achieve the same purpose. Depending on the needs, the amine washing tower and amine washing tower can also be set at a suitable location between compressor #2 and booster compressor #2. Depending on the processing parameters, compressor #2 and booster compressor #2 can also be two stages of a single compressor, which can reduce investment and save space.

[0037] A process for directly obtaining high-purity helium from natural gas includes the following steps:

[0038] Purified natural gas from the natural gas processing plant first enters a precision oil filter to remove oil droplets suspended in the natural gas brought in by the upstream oil-lubricated piston compressor, and then enters the No. 1 membrane separator.

[0039] After permeation treatment by membrane separator #1, non-permeate gas without helium and permeate gas containing helium are obtained. The non-permeate gas is sent directly to the natural gas pipeline network with almost no pressure reduction. The permeate gas is at atmospheric pressure, and the flow rate is greatly reduced due to the increased helium concentration in the permeate gas. It is then pressurized to the feed gas pressure by compressor #1 and sent to the amine washing tower.

[0040] The amine washing tower removes a large amount of CO2 and H2S, and then the amine liquid entrained in the process gas is removed by the amine washing tower before entering the No. 2 membrane separator.

[0041] After permeation treatment by membrane separator #2, the helium concentration in the permeate gas is further increased. It is then pressurized to a certain pressure by compressor #2 and directly enters the COS medium-temperature hydrolysis tower without cooling.

[0042] In the COS medium-temperature hydrolysis tower, COS is converted into H2S using compression heat and hydrolysis catalyst. After being cooled by a water cooler, it enters the fine desulfurization tower to remove all sulfides. It then enters the No. 2 booster to be pressurized to near the pressure of the raw natural gas. Without cooling, it directly enters the catalytic dehydrogenation reactor to remove all H2. After being cooled by the dehydrogenation cooler, it enters the No. 3 membrane separator.

[0043] After being permeated by membrane separator #3, the helium concentration in the resulting permeate gas is increased to the concentration required by the low-temperature purification unit. It is then pressurized to the required pressure by booster compressor #2 and sent to the TSA purification system.

[0044] In the TSA purification system, residual CO2, H2O, and sulfides are removed before entering the low-temperature purification unit;

[0045] In the low-temperature purification unit, the remaining CH4, N2, Ar, O2, and Ne impurities are removed to obtain helium with a purity of 99.999%.

[0046] The non-permeable gas from membrane separators #1 and #2 is directly fed into the natural gas tail gas pipeline network. The non-permeable gas from membrane separator #3, which contains a large amount of helium, is returned to the inlet of membrane separator #2 for recovery. The regeneration medium of the TSA purification system uses the non-permeable gas from membrane separator #1, and the regenerated tail gas is fed into the natural gas tail gas pipeline network.

[0047] Compared with the prior art, the advantages of the present invention are as follows: Based on the current situation of domestic resources, the present invention is mainly used to solve the problem of helium purification and preparation in helium-poor and extra-poor helium natural gas. It adopts a multi-stage membrane separation + low temperature adsorption process to extract helium-poor natural gas and obtain high-purity helium or liquid helium.

[0048] Specifically, this invention proposes installing a precision oil filter at the natural gas inlet to remove suspended oil droplets carried into the natural gas from the upstream oil-lubricated piston compressor, thus avoiding any impact on the efficiency of the membrane separator. The use of a combination of an amine scrubbing tower and an amine scrubbing tower for desulfurization and decarbonization offers high operational flexibility, particularly suitable for natural gas conditions in oil fields with high H2S and CO2 content. The amine scrubbing tower effectively prevents solvent entrainment from adversely affecting subsequent membrane separators. Utilizing the heat of compression for COS hydrolysis and dehydrogenation avoids the "cold / hot" problems of the process flow, while also eliminating the need for separate heating equipment and reducing cooling water consumption. Membrane separators #2 and #3 operate directly at pressures close to the feed gas, resulting in high membrane yield and separation performance, significantly reducing membrane costs. The required area, investment, and energy consumption of the separator are further reduced compared to existing technologies. This invention uses a three-stage membrane separator for helium enrichment. The No. 3 membrane separator is not segmented, and the non-permeable gas is directly circulated to the inlet of the No. 2 membrane separator, reducing the number of equipment, membrane investment, and compression power significantly. A TSA purification unit is set up before low-temperature purification to completely remove CO2 and H2O. Non-permeable tail gas is used for regeneration, resulting in high helium yield and no N2 impurities entering the process gas. Low-temperature adsorption below the liquid nitrogen temperature zone is used for purification, which has good selectivity and high efficiency, and can completely remove impurities such as Ar and Ne that are difficult to adsorb by room temperature methods, effectively ensuring product purity. Oxygen is produced by water electrolysis to provide the oxygen required for oxidative dehydrogenation, with high purity and no impact from impurities such as Ar and Ne. Attached Figure Description

[0049] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;

[0050] Figure 2 This is the first process flow diagram of Embodiment 2 of the present invention;

[0051] Figure 3This is the second process flow diagram of Embodiment 2 of the present invention;

[0052] Figure 4 This is the third process flow diagram of Embodiment 2 of the present invention;

[0053] Figure 5 This is the fourth process flow diagram of Embodiment 2 of the present invention. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0055] Example 1:

[0056] like Figure 1 As shown, the device for directly obtaining high-purity helium from natural gas in this embodiment includes:

[0057] Precision oil filter 1 is equipped with an air inlet for input of lean helium-containing sulfur natural gas, used to remove suspended oil droplets in natural gas;

[0058] Membrane separation system A, located downstream of precision oil filter 1, includes multiple sets of membrane separators connected in series, used to perform permeation separation on materials to obtain non-permeable gas sent to the natural gas tail gas pipeline and permeable gas enriched with helium.

[0059] Acid gas removal unit B is connected to membrane separation system A and is used to remove CO2 and H2S from process gas and prevent volatile amine liquid from being introduced.

[0060] Fine desulfurization unit C is connected to membrane separation system A and located downstream of acid gas removal unit B, and is used to remove sulfur-containing substances from process gas;

[0061] Dehydrogenation unit D is connected to membrane separation system A and located downstream of fine desulfurization unit C, and is used to remove residual H2 from process gas;

[0062] The re-purification system 16, located downstream of the membrane separation system A and the dehydrogenation unit D, is used to remove residual CO2, H2O, sulfides, etc. from the process gas; and

[0063] The low-temperature impurity removal unit 17 is located downstream of the re-purification system and is used to remove CH4, N2, Ar, O2, Ne and other impurities contained in the process gas.

[0064] The precision oil filter 1 in this embodiment can be a multi-stage filter connected in series or in parallel. The filter can be one or more of the following types: sintered, activated carbon adsorption, fiber, and coalescing.

[0065] The membrane separation system A in this embodiment is a multi-stage series membrane separator group, which can also be connected in parallel, depending on the specific needs. The membrane separation system A in this embodiment includes membrane separator 2, membrane separator 6, and membrane separator 14 connected in series. A compressor 3 for pressurizing the process gas is installed between membrane separator 2 and membrane separator 6. A compressor 7 and a booster compressor 11 for pressurizing the process gas are installed between membrane separator 6 and membrane separator 14. A compressor 15 for pressurizing the process gas is installed between membrane separator 14 and the re-purification system 16. Acid gas removal unit B is located between membrane separator 2 (1#) and membrane separator 6 (2#) and downstream of compressor 3 (1#); fine desulfurization unit C is located between membrane separator 6 (2#) and membrane separator 14 (3#) and between compressor 7 (2#) and booster compressor 11 (2#); dehydrogenation unit D is located between membrane separator 6 (2#) and membrane separator 14 (3#) and downstream of booster compressor 11 (2#).

[0066] The acid gas removal unit B mentioned above includes an amine washing tower 4 and an amine washing tower 5 connected in series along the gas flow direction. The amine washing tower 4 is used to remove a large amount of CO2 and H2S from the process gas, and the amine washing tower 5 is used to remove the entrained amine liquid from the process gas.

[0067] The aforementioned fine desulfurization unit C includes a COS intermediate-temperature hydrolysis tower 8, a water cooler 9, and a fine desulfurization tower 10 connected in series. The COS intermediate-temperature hydrolysis tower 8 is used to convert COS into H2S, the water cooler 9 is used to cool the process gas, and the fine desulfurization tower 10 is used to remove all sulfides. This embodiment may also include an electrolytic water device 19 for providing oxygen. The oxygen output end of the electrolytic water device 19 is connected to the inlet of the fine desulfurization tower 10 to provide the required high-purity oxygen to the fine desulfurization tower 10 and the dehydrogenation unit D.

[0068] The aforementioned dehydrogenation unit D includes an upstream catalytic dehydrogenation reactor 12 and a downstream dehydrogenation cooler 13. The catalytic dehydrogenation reactor 12 is used to remove residual hydrogen from the process gas, and the dehydrogenation cooler 13 is used to cool the process gas after the removal of residual H2, in preparation for it to enter the downstream membrane separator.

[0069] In this embodiment, the top of membrane separator 2 is connected to a first pipe 01 that connects its non-permeable gas side to the natural gas pipeline network. The top of membrane separator 6 is connected to a second pipe 02 that connects its non-permeable gas side to the first pipe 01. The top of membrane separator 14 is connected to a third pipe 03 that connects its non-permeable gas side to the pipeline between compressor 3 and the inlet of membrane separator 6. The re-purification system 16 is a TSA purification system, which includes an adsorption unit and a regeneration unit. The adsorption unit is filled with an adsorbent for adsorbing CO2, water, heavy hydrocarbons, and some sulfides. The regeneration unit includes a fourth pipe 04 and a fifth pipe 05. The fourth pipe 04 is connected near the inlet of the first pipe 01 and between the top inlet of the TSA purification system, and is used to input some of the non-permeable gas in the first pipe 01 into the TSA purification system to purge impurities adsorbed in the adsorbent. The fifth pipe 05 is connected between the top outlet of the TSA purification system and the second pipe 02.

[0070] In this embodiment, the cryogenic impurity removal unit 17 can be a cryogenic purification unit or a PSA process device. The PSA tail gas can be recycled to the inlet of compressor #1 (3) or compressor #2 (7) to obtain high-purity helium. The non-permeable gas from membrane separator #3 (14) is directly returned to the inlet of membrane separator #2 (6), or it can be returned to compressor #1 (2) to achieve the same purpose. Depending on the needs, the amine washing tower 4 and amine washing tower 5 can also be located at a suitable position between compressor #2 (7) and booster compressor #2 (11). Based on optimized processing parameters, compressor #2 (7) and booster compressor #2 (11) can also be two stages of a single compressor, reducing investment and saving space. In this embodiment, a liquefier 18 can also be installed downstream of the cryogenic impurity removal unit 17 to convert helium into liquid helium for storage and transportation.

[0071] The process for directly obtaining high-purity helium from natural gas in this embodiment includes the following steps:

[0072] The purified natural gas from the natural gas processing plant has a pressure of 4.0 MPa. It first enters the precision oil filter 1 to remove the oil droplets suspended in the natural gas brought in by the upstream oil-lubricated piston compressor, and then enters the No. 1 membrane separator 2.

[0073] After permeation treatment by membrane separator 2 (No. 1), non-permeate gas (<200ppm) without helium and permeate gas (concentrated 7-9 times) containing helium are obtained. The non-permeate gas is sent directly to the natural gas pipeline network with almost no pressure reduction. The permeate gas is at near atmospheric pressure or vacuum. The helium concentration in the permeate gas increases while the flow rate decreases significantly. It is then pressurized to 4.0MPa by compressor 3 (No. 1) and sent to amine washing tower 4.

[0074] Amine washing tower 4 removes a large amount of CO2 and H2S, and then amine washing tower 5 removes the amine liquid entrained in the process gas before entering membrane separator 6.

[0075] After permeation treatment by membrane separator 6, the helium concentration in the permeate gas is further increased (4-6 times). It is then pressurized to 2.0 MPa and 100°C by compressor 7 before entering COS medium-temperature hydrolysis tower 8.

[0076] In the COS medium-temperature hydrolysis tower 8, COS is converted into H2S using compression heat and hydrolysis catalyst. After being cooled to 40°C by a water cooler, it enters the fine desulfurization tower where sulfides are removed to below 0.1ppm under the action of O2 and desulfurizer. It then enters the No. 2 booster 11 to be pressurized to close to 4.0MPa and directly enters the catalytic dehydrogenation reactor 12 at 135°C to remove all hydrogen. After being cooled to 40°C by the dehydrogenation cooler 13, it enters the No. 3 membrane separator 14.

[0077] After permeation treatment by membrane separator 14, the helium concentration in the permeate gas is concentrated to the concentration required by the low-temperature purification unit (>40%), and then pressurized to 2.0 MPa by booster compressor 11 before being sent to the TSA purification system.

[0078] In the TSA purification system, residual CO2, H2O, and sulfides are removed before entering the low-temperature purification unit;

[0079] In the low-temperature purification unit, the remaining CH4, N2, Ar, O2, and Ne impurities are removed in the temperature range close to the operating temperature of -200℃ to obtain helium with a purity of 99.999%.

[0080] In this process, the non-permeable gas from membrane separators 1#2 and 2#6, with a helium content of less than 200 ppm, is directly fed into the natural gas tail gas pipeline. The non-permeable gas from membrane separator 3#14, containing a large amount of helium, is returned to the inlet of membrane separator 2#6 for recovery. The regeneration medium for the TSA purification system uses the non-permeable gas from membrane separator 1#2, and the regenerated tail gas is fed into the natural gas tail gas pipeline. The helium recovery rate of the entire process is over 93%.

[0081] Example 2:

[0082] like Figures 2-5 As shown, the device for directly obtaining high-purity helium from natural gas in this embodiment can also adopt such a structural modification. Of course, its operating principle and basic process steps are consistent with those in Embodiment 1.

Claims

1. A device for directly obtaining high-purity helium from natural gas, characterized in that... include: The precision oil filter is equipped with an inlet for the input of lean helium-containing sulfur natural gas, used to remove suspended oil droplets from the natural gas; A membrane separation system, located downstream of the precision oil filter, includes at least two sets of membrane separators connected in series, used to perform permeation separation on the material to obtain non-permeable gas for the natural gas tail gas pipeline and permeable gas enriched with helium. An acid gas removal unit is connected to the membrane separation system and is used to remove CO2, H2S, and amine liquid from the process gas; The fine desulfurization unit is connected to the membrane separation system and located downstream of the acid gas removal unit, and is used to remove sulfur-containing substances from the process gas. A dehydrogenation unit, connected to the membrane separation system and located downstream of the fine desulfurization unit, is used to remove residual hydrogen from the process gas. A re-purification system, located downstream of the membrane separation system and the dehydrogenation unit, is used to remove at least one of CO2, H2O, and sulfides contained in the process gas. as well as A low-temperature impurity removal unit is located downstream of the re-purification system and is used to remove at least one of CH4, N2, Ar, O2, and Ne contained in the process gas.

2. The apparatus for directly obtaining high-purity helium from natural gas according to claim 1, characterized in that: The acid gas removal unit is connected in series between two adjacent membrane separators and includes an amine washing tower and an amine washing tower connected in series along the gas flow direction. The amine washing tower is used to remove a large amount of CO2 and H2S from the process gas, and the amine washing tower is used to remove the entrained amine liquid from the process gas.

3. The apparatus for directly obtaining high-purity helium from natural gas according to claim 1, characterized in that: The fine desulfurization unit is connected in series between two adjacent membrane separators and includes a COS medium-temperature hydrolysis tower, a water cooler, and a fine desulfurization tower connected in series. The COS medium-temperature hydrolysis tower is used to convert COS into H2S, the water cooler is used to cool the process gas, and the fine desulfurization tower is used to remove all sulfides.

4. The apparatus for directly obtaining high-purity helium from natural gas according to claim 3, characterized in that: It also includes a water electrolysis device for providing oxygen, the oxygen output end of which is connected to the inlet of the fine desulfurization tower to provide the required high-purity oxygen to the fine desulfurization tower and the dehydrogenation unit.

5. The apparatus for directly obtaining high-purity helium from natural gas according to any one of claims 1 to 4, characterized in that: The dehydrogenation unit is connected in series between two adjacent membrane separators and includes an upstream catalytic dehydrogenation reactor and a downstream dehydrogenation cooler. The catalytic dehydrogenation reactor is used to remove residual H2 hydrogen from the process gas, and the dehydrogenation cooler is used to cool the process gas after the removal of residual H2 in preparation for entering the downstream membrane separator.

6. The apparatus for directly obtaining high-purity helium from natural gas according to any one of claims 1 to 4, characterized in that: The membrane separation system includes membrane separator #1, membrane separator #2, and membrane separator #3 connected in series. A compressor #1 for pressurizing the process gas is installed between membrane separator #1 and membrane separator #2. A compressor #2 and a booster compressor for pressurizing the process gas are installed between membrane separator #2 and membrane separator #3. A compressor #3 for pressurizing the process gas is installed between membrane separator #3 and the repurification system.

7. The apparatus for directly obtaining high-purity helium from natural gas according to claim 6, characterized in that: The acid gas removal unit is located between membrane separator #1 and membrane separator #2 and downstream of compressor #1; the fine desulfurization unit is located between membrane separator #2 and membrane separator #3 and between compressor #2 and booster compressor #2; the dehydrogenation unit is located between membrane separator #2 and membrane separator #3 and downstream of booster compressor #2.

8. The apparatus for directly obtaining high-purity helium from natural gas according to claim 6, characterized in that: The top of membrane separator #1 is connected to a first pipe that connects its non-permeable gas side to the natural gas pipeline network. The top of membrane separator #2 is connected to a second pipe that connects its non-permeable gas side to the first pipe. The top of membrane separator #3 is connected to a third pipe that connects its non-permeable gas side to the pipeline between compressor #1 and the inlet of membrane separator #2.

9. The apparatus for directly obtaining high-purity helium from natural gas according to claim 8, characterized in that: The re-purification system is a TSA purification system, which includes an adsorption unit and a regeneration unit. The adsorption unit is filled with an adsorbent for adsorbing CO2, water, heavy hydrocarbons, and some sulfides. The regeneration unit includes a fourth pipe and a fifth pipe. The fourth pipe is connected near the inlet of the first pipe to the top inlet of the TSA purification system, and is used to introduce some non-permeable gas from the first pipe into the TSA purification system to purge impurities adsorbed in the adsorbent. The fifth pipe is connected between the top outlet of the TSA purification system and the second pipe.

10. A process for directly obtaining high-purity helium from natural gas, characterized in that... Includes the following steps: Purified natural gas from the natural gas processing plant first enters a precision oil filter to remove oil droplets suspended in the natural gas brought in by the upstream oil-lubricated piston compressor, and then enters the No. 1 membrane separator. After permeation treatment by membrane separator #1, non-permeate gas without helium and permeate gas containing helium are obtained. The non-permeate gas is sent directly to the natural gas pipeline network with almost no pressure reduction. The permeate gas is at atmospheric pressure, and the flow rate is greatly reduced due to the increased helium concentration in the permeate gas. It is then pressurized to the feed gas pressure by compressor #1 and sent to the amine washing tower. The amine washing tower removes a large amount of CO2 and H2S, and then the amine liquid entrained in the process gas is removed by the amine washing tower before entering the No. 2 membrane separator. After permeation treatment by membrane separator #2, the helium concentration in the resulting permeate gas is further increased. It is then pressurized to a certain pressure by compressor #2 and directly enters the COS medium-temperature hydrolysis tower. In the COS medium-temperature hydrolysis tower, COS is converted into H2S by compression heat and hydrolysis catalyst. After being cooled by water cooler, it enters the fine desulfurization tower to remove all sulfides. It then enters the No. 2 booster to pressurize to near the pressure of the raw natural gas. Without cooling, it directly enters the catalytic dehydrogenation reactor to remove all hydrogen. After being cooled by dehydrogenation cooler, it enters the No. 3 membrane separator. After being permeated by the No. 3 membrane separator, the helium concentration in the resulting permeate gas is increased to the concentration required by the low-temperature impurity removal unit. It is then pressurized to the required pressure by the No. 2 booster and sent to the TSA purification system. In the TSA purification system, residual CO2, H2O, and sulfides are removed before entering the low-temperature impurity removal unit. In the low-temperature impurity removal unit, the remaining CH4, N2, Ar, O2, and Ne impurities are removed to obtain helium gas with a purity of 99.999%. The non-permeable gas from membrane separators #1 and #2 is directly fed into the natural gas tail gas pipeline network. The non-permeable gas from membrane separator #3, which contains a large amount of helium, is returned to the inlet of membrane separator #2 for recovery. The regeneration medium of the TSA purification system uses the non-permeable gas from membrane separator #1, and the regenerated tail gas is fed into the natural gas tail gas pipeline network.

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