Method for extracting helium and producing hydrogen by methanation reaction coupling membrane separation technology and application

Abstract

The invention relates to the field of refining, and discloses a method for extracting helium and producing hydrogen through a methanation reaction coupling membrane separation technology and application. The method comprises the following steps: (1) carrying out methanation reaction on first mixed gas of raw material gas and optionally supplemented hydrogen to remove most of hydrogen so as to obtain second mixed gas; the hydrogen-carbon ratio in the first mixed gas is controlled to meet the condition that H2 / (4CO2 + 3CO) is larger than or equal to 1; (2) the second mixed gas is subjected to dehydration and CO2 removal treatment and then passes through a membrane separation unit, and permeated gas containing helium and hydrogen is obtained; (3) deeply dehydrogenating the permeated gas through a helium refining unit to obtain high-purity helium; and collecting the hydrogen removed by the helium refining unit to prepare the hydrogen. According to the method, high-purity helium and hydrogen can be extracted and produced by taking a technology of methanation dehydrogenation and high-molecular polymer membrane helium extraction by adjusting a methanation hydrogen-carbon ratio as a core and combining a palladium membrane and / or alloy adsorption dehydrogenation technology.

Description

Technical Field

[0001] The present invention relates to the field of refining, and in particular to the technical field of extracting helium from industrial tail gas and producing ultrapure hydrogen, and in particular to a method and application of extracting helium and producing hydrogen by coupling a methanation reaction with a membrane separation technology. Background Art

[0002] Helium is widely present in natural gas. Some chemical plants that use natural gas as raw material often have a certain concentration of helium in their tail gas. However, the presence of hydrogen, carbon monoxide, and carbon dioxide and the large fluctuations in component concentrations make it very difficult to extract high-purity helium from the system using existing process technology. It has almost no economic value, resulting in the inability to utilize the helium resources in the system.

[0003] The main reasons are that the hydrogen concentration is high, the boiling points of hydrogen and helium are low, and the kinetic diameters are similar; carbon dioxide has a smaller kinetic diameter and a higher boiling point; carbon monoxide has a lower boiling point and is toxic to precious metals; and the component concentrations fluctuate greatly.

[0004] Pore ​​screening membranes with different diameters based on separation kinetics are not effective in separating hydrogen, helium and carbon dioxide. Cryogenic processes that separate components based on different boiling points require high energy consumption for separating helium, hydrogen and carbon monoxide and are basically unable to separate hydrogen and helium. Although dense alloy membranes and alloy adsorption, catalytic combustion and electrochemical dehydrogenation technologies have good dehydrogenation effects, the precious metals or catalysts containing precious metals are easily poisoned and deactivated by reaction with carbon monoxide. In addition, the flux and adsorption capacity of alloy membranes and adsorbents are limited, and the construction and maintenance costs are high. Chemical oxidation processes such as catalytic combustion generate a large amount of reaction heat, which poses a safety hazard. At the same time, other impurities such as oxygen and nitrogen need to be introduced, which are usually accompanied by the generation of carbon dioxide.

[0005] In summary, to extract ultrapure helium from this type of gas, it is necessary to remove impurities such as hydrogen, carbon monoxide, carbon dioxide, methane, and nitrogen at the same time, which is basically impossible to achieve efficiently and within a reasonable economic range with existing technologies and combined processes. However, the helium resources contained in this type of waste gas are considerable. In order to ensure the safety of my country's helium resources, the development and application of new process technologies are urgently needed. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the prior art that it is impossible to efficiently extract high-purity helium from industrial tail gas and remove hydrogen, carbon monoxide, carbon dioxide, methane, nitrogen and other impurities within a reasonable economic range, and to provide a method and application of extracting helium and producing hydrogen by coupling methanation reaction with membrane separation technology. The method takes methanation dehydrogenation and high molecular polymer membrane helium extraction technology as the core by adjusting the methanation-hydrogen carbon ratio, and by combining palladium membrane and / or alloy adsorption dehydrogenation technology, it is possible to achieve the technology of extracting and producing high-purity helium and hydrogen while ensuring the yield.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for extracting helium and producing hydrogen by coupling methanation reaction with membrane separation technology, wherein the method comprises:

[0008] (1) subjecting a first mixed gas of a feed gas and optionally supplemented hydrogen to a methanogenic reaction unit to remove most of the hydrogen to obtain a second mixed gas; wherein the hydrogen-to-carbon ratio in the first mixed gas is controlled to meet the following conditions: H2 / (4CO2+3CO)≥1;

[0009] (2) subjecting the second mixed gas to dehydration and CO2 removal treatment and then passing through a membrane separation unit to obtain a permeate gas containing helium and hydrogen;

[0010] (3) deep dehydrogenating the permeate gas through a helium refinement unit to obtain high-purity helium; and collecting the hydrogen removed by the helium refinement unit to prepare hydrogen.

[0011] A second aspect of the present invention provides an application of the aforementioned method in extracting helium and preparing hydrogen from industrial tail gas.

[0012] Through the above technical solution, the technical solution of the present invention has the following beneficial effects:

[0013] (1) By coupling methanation technology, hydrogen, carbon monoxide, and carbon dioxide in the system can be fully removed and reusable methane gas can be generated; in addition, the removal of hydrogen and carbon dioxide during the methanation process enables the polymer separation membrane to improve the helium recovery efficiency while reducing carbon dioxide emissions; in addition, the carbon monoxide removed during the methanation process can eliminate the toxicity to the alloy material, thereby improving its life and economy.

[0014] (2) The present invention uses alloy membrane separation and adsorption technology to perform deep dehydrogenation to produce high-purity helium and high-purity hydrogen. After being collected, the hydrogen can be added to the methanation reaction to enhance the impact load resistance of the methanation system, so that the reaction can proceed fully without generating carbon deposits.

[0015] (3) The high-purity helium concentration of the present invention can reach 99.999%, with a yield greater than 90%; the high-purity hydrogen concentration can reach 99.999%, with a yield greater than 90%; and the methane concentration can reach >85%, thereby increasing considerable economic benefits for chemical plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for extracting helium and producing hydrogen by coupling methanation reaction with membrane separation technology provided by the present invention.

[0017] Description of Reference Numerals

[0018] S1-raw gas;

[0019] S2-mixed gas obtained after methanation reaction in the methanation reaction unit;

[0020] S3-mixed gas obtained by dehydrating and removing CO2 in a dehydration and CO2 removal unit;

[0021] S4-permeate gas separated by the membrane in the membrane separation unit;

[0022] S5-the retentate gas that has not passed through the membrane separation in the membrane separation unit is recycled;

[0023] S6-high purity helium after deep dehydrogenation through a helium refinement unit (alloy / palladium membrane);

[0024] S7 - high purity hydrogen separated by helium refinement unit (alloy / palladium membrane);

[0025] S8-high purity hydrogen discharged from the hydrogen storage tank;

[0026] S9-Hydrogen is replenished from the hydrogen storage tank to the methanation reaction unit. DETAILED DESCRIPTION

[0027] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0028] As mentioned above, the first aspect of the present invention provides a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology, wherein the method comprises:

[0029] (1) subjecting a first mixed gas of a feed gas and optionally supplemented hydrogen to a methanogenic reaction unit to remove most of the hydrogen to obtain a second mixed gas; wherein the hydrogen-to-carbon ratio in the first mixed gas is controlled to meet the following conditions: H2 / (4CO2+3CO)≥1;

[0030] (2) subjecting the second mixed gas to dehydration and CO2 removal treatment and then passing through a membrane separation unit to obtain a permeate gas containing helium and hydrogen;

[0031] (3) deep dehydrogenating the permeate gas through a helium refinement unit to obtain high-purity helium; and collecting the hydrogen removed by the helium refinement unit to prepare hydrogen.

[0032] The inventor of the present invention found that the initial purpose of the present invention is to extract CO, CO2, H2, He and other gases such as chemical exhaust gas to obtain high-purity helium. Since the membrane separation technology needs to be the core of the process, the enrichment and purification of He also enriches H2. In order to obtain high-purity He, the enriched H2 needs to be deeply removed. Although the oxidation reaction efficiency is very high, hydrogen energy is a secondary energy source, and high-purity hydrogen is an important and high-value-added chemical raw material. Recycling and purifying H2 will save energy and increase efficiency. The alloy dehydrogenation can achieve the expected results, but it is not suitable for removing high-concentration hydrogen. Further, in order to prevent the alloy catalyst from CO poisoning and reduce carbon emissions, it is associated with the use of methanation technology to remove H2, CO, and CO2 through reaction at the same time. However, the methanation reaction requires sufficient hydrogen to support the reaction, otherwise it is easy to cause carbon deposition side reactions and low conversion rate. It is further associated with the high-purity hydrogen adsorbed by the alloy for adjustment. Although the whole process cannot achieve 100% recovery of materials and energy, high-value-added He and H2 can be produced, and a large amount of synthetic natural gas is also produced. A renewable, high value-added green recycling system has been established.

[0033] According to the present invention, preferably, 1.25≥H2 / (4CO2+3CO)≥1; more preferably, the hydrogen-carbon ratio satisfies: H2 / (4CO2+3CO)=1.1. In the present invention, it should be noted that the hydrogen-carbon ratio H2 / (4CO2+3CO) refers to the ratio of hydrogen to carbon monoxide and carbon dioxide; if the hydrogen-carbon ratio is too high, it will cause excessive hydrogen to affect subsequent treatment, and ultimately result in poor overall dehydrogenation effect; if the hydrogen-carbon ratio is too low, it will lead to insufficient reaction, while increasing the risk of carbon deposition and causing catalyst deactivation.

[0034] According to the present invention, the device used in the method includes a methanation reaction unit, a dehydration and CO2 removal processing unit, a membrane separation unit, a helium refinement unit (alloy / palladium membrane processing unit) and a hydrogen storage tank unit.

[0035] According to the present invention, in step (1), the raw gas is passed through a methanation reaction unit. After the methanation reaction, the conversion rate of hydrogen is greater than 99%, and the removal rates of carbon monoxide and carbon dioxide are greater than 99.9%.

[0036] According to the present invention, in step (1), the conditions of the methanation reaction include: a temperature of 500-700°C, within which the reaction activity can be ensured while preventing the CO disproportionation reaction from inhibiting carbon deposition; in addition, the temperature of the methanation reaction inlet gas (i.e., S9) is greater than 300°C.

[0037] According to the present invention, the methanation reaction can adopt one or more of an adiabatic fixed bed process, an isothermal fixed bed (tube-in-tube) process, a slurry bed process and a fluidized bed process, and can be a cyclic and / or non-cyclic type.

[0038] According to the present invention, preferably, the methanation reaction is a cyclic multi-stage fixed bed process.

[0039] According to the present invention, the catalyst used in the methanation reaction may be a high-temperature catalyst, which includes a Davy-GRC catalyst and / or an MCR-2X catalyst, wherein the nickel content in the high-temperature catalyst is greater than 30% and is resistant to high temperatures above 600°C.

[0040] According to the present invention, the Davy-GRC catalyst includes a GRC-S2S type catalyst.

[0041] According to the present invention, preferably, the catalyst used in the methanation reaction is a GRC-S2S catalyst, which has a shape of a 3.4 mm × 3.5 mm black cylinder and a bulk density of 1450 kg / m 3 The catalyst has a wide application temperature range and has good catalytic activity between 320-670℃. It has a wide applicable pressure range and can maintain structural stability between 3-6MPa. The catalyst life is more than 2 years, with high cost performance.

[0042] In the present invention, the process used for the methanation reaction can be at least one of the new non-circulating VESTA coal-to-natural gas process developed by Denmark's Topsoe, Britain's Davy, Lurgi, Foster Wheeler and Clariant in the United States, and the new non-circulating methanation technology (NRMT) developed by Beijing Huafu, Dalian Ruike, and China Coal Longhua.

[0043] According to the present invention, in step (2), dehydration and CO2 removal are carried out through a dehydration and CO2 removal treatment unit, which is achieved by molecular sieve pressure swing adsorption technology; the adsorbent can be selected from one or more of 3A, 4A and 13X molecular sieves; wherein the adsorption pressure can be 0.01-10Mpa, and the air velocity can be 1m 3 / m 3 ·h-100m 3 / m 3 h; 13X molecular sieve is preferred as adsorbent, adsorption pressure is 2-5Mpa, space velocity is 3m 3 / m 3 ·h-20m 3 / m 3 ·h.

[0044] According to the present invention, in step (2), the material of the separation membrane provided in the membrane separation unit is one or more of polysulfone, polyethersulfone, polyimide, polypropylene, polyethylene, synthetic resin, polyvinylidene fluoride, polytetrafluoroethylene, polyetheretherketone, polybenzimidazole (PBI), block copolymer, cellulose acetate membrane, polycarbonate membrane, polymethyl methacrylate membrane, silicon dioxide membrane, zeolite molecular sieve membrane, carbon molecular sieve membrane and metal organic framework material (MOFs);

[0045] Preferably, the separation membrane is a polyimide hollow fiber membrane; more preferably, the polyimide hollow fiber membrane is a hollow fiber membrane disclosed in CN115501758B.

[0046] In a further preferred case, in the present invention, the polyimide hollow fiber membrane is a PI hydrogen-helium hollow fiber separation membrane (referred to as Beijing Chemical Research Institute PI separation membrane) prepared by (BHY_SINO) Sinopec (Beijing) Chemical Research Institute Co., Ltd. (formerly known as: Beijing Chemical Research Institute of China Petrochemical Corporation).

[0047] According to the present invention, the separation membrane may be one or more of a spiral membrane, a hollow fiber membrane, a flat membrane and a tubular membrane.

[0048] According to the present invention, the separation membrane may be one or more of a homogeneous membrane, a heterogeneous membrane and a composite membrane.

[0049] According to the present invention, the separation membrane may be a primary membrane and / or a multi-stage membrane. In the present invention, if the separation membrane is a combination of a primary membrane and a multi-stage membrane, it is a multi-stage membrane.

[0050] According to the present invention, in step (2), the total concentration of H2 and He in the permeate gas is greater than 90%; and the total yield of H2 and He in the permeate gas is greater than 85%.

[0051] According to the present invention, in step (2), the membrane separation conditions include: membrane separation temperature of 0-120°C, and transmembrane pressure of 0.1-10 MPa; preferably, membrane separation temperature of 10-80°C, and transmembrane pressure of 2-5 MPa.

[0052] According to the present invention, the raw gas is a gas system containing hydrogen, helium, carbon monoxide and methane, for example, it can be factory purge gas.

[0053] According to the present invention, preferably, the raw gas contains one or more of methane, hydrogen, helium, nitrogen, carbon monoxide and carbon dioxide.

[0054] According to the present invention, preferably, the content of hydrogen is 20-35% by volume based on the total volume of the raw gas.

[0055] According to the present invention, preferably, based on the total volume of the raw gas, the content of hydrogen is 20-35% by volume, the content of methane is 20-50% by volume, the content of helium is 10-20% by volume, the content of nitrogen is 0-10% by volume, the content of carbon monoxide is 5-10% by volume, and the content of carbon dioxide is 1-5% by volume.

[0056] According to the present invention, the total content of carbon monoxide and carbon dioxide is less than 10% by volume.

[0057] According to the present invention, in step (3), the helium refinement unit includes alloy adsorption and palladium alloy membrane separation.

[0058] According to the present invention, the palladium membrane provided in the palladium alloy membrane separation is selected from one or more of a tubular palladium membrane, a porous carrier composite membrane and an alloy membrane; in the present invention, the carrier in the porous carrier composite membrane can be at least one of porous ceramics, porous Vickers glass, palladium-yttrium alloy membrane, palladium-cerium alloy membrane, palladium-copper alloy membrane, palladium-gold alloy membrane, palladium-nickel alloy membrane and palladium-silver alloy membrane.

[0059] According to the present invention, the palladium membrane may have a thickness of 5-100 μm, and preferably a porous ceramic palladium-copper alloy with a thickness of 20 μm.

[0060] According to the present invention, the conditions for separation of the palladium alloy membrane include: palladium membrane dehydrogenation temperature of 300-500° C., palladium membrane dehydrogenation pressure of 1-50 MPa; preferably, the pressure is 1-5 MPa.

[0061] According to the present invention, the adsorbent used for the alloy adsorption is selected from one or more of rare earth hydrogen storage alloys, titanium hydrogen storage alloys, zirconium hydrogen storage alloys, vanadium hydrogen storage alloys and magnesium hydrogen storage alloys; preferably, Mg2Ni hydrogen storage alloy (Xi'an Qiyue Mg-Ni binary hydrogen storage alloy) is selected.

[0062] According to the present invention, the conditions for alloy adsorption include: adsorption temperature of 300-400°C, adsorption pressure of 2.4-40Mpa; desorption temperature of 300-400°C, desorption pressure of 0.1-2.4Mpa; bed space velocity of 1m 3 / m 3 ·h-50m 3 / m 3 ·h; preferably, the adsorption temperature is 300-350°C, the adsorption pressure is 5-10Mpa; the desorption temperature is 400°C, the desorption pressure is 0.1-0.5Mpa; the bed space velocity is 10m 3 / m 3 ·h-50m 3 / m 3 ·h.

[0063] According to a particularly preferred embodiment of the present invention, Figure 1 As shown, the present invention provides a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology, wherein the method comprises:

[0064] (1) subjecting a first mixed gas of the raw gas S1 and optionally supplemented hydrogen S9 to a methanation reaction unit for a methanation reaction to remove most of the hydrogen, thereby obtaining a second mixed gas S2;

[0065] In step (1), the raw gas S1 passes through a methanogenic reaction unit, where hydrogen, carbon dioxide, and carbon monoxide react and are mostly removed to generate a mixed gas containing water, methane, a small amount of unreacted hydrogen, and trace amounts of carbon dioxide, carbon monoxide, and other gases that do not participate in the reaction. The mixed gas is heat exchanged to form S2, and the waste heat is recovered to produce medium-pressure steam and to preheat S1 and S4.

[0066] The hydrogen-carbon ratio in the first mixed gas is controlled to meet the following conditions: 1.25≥H2 / (3CO+4CO2)≥1, that is, hydrogen is replenished to the methanation reaction unit by monitoring the hydrogen concentration, so as to achieve a substantially complete reaction of the hydrogen without generating carbon deposits;

[0067] (2) subjecting the second mixed gas to dehydration and CO2 removal treatment and then passing through a membrane separation unit to obtain a permeate gas S4 containing helium and hydrogen;

[0068] In step (2), S2 is deeply dehydrated and decarbonized to form a mixed gas S3, which enters the polymer organic separation membrane unit. Most of the helium and hydrogen pass through the membrane to form a permeate gas S4. The residual gas S5 that does not pass through the membrane mainly contains methane and nitrogen and can be reused.

[0069] (3) deep dehydrogenating the permeate gas S4 through a helium refinement unit to obtain high-purity helium S6; and collecting the hydrogen-containing S7 removed by the helium refinement unit in a hydrogen storage tank to prepare hydrogen S8;

[0070] In step (3), S4 undergoes deep dehydrogenation to form high-purity helium S6, and the separated high-purity hydrogen S7 is stored in a hydrogen storage tank. When it is detected that the hydrogen concentration of the raw gas inlet is insufficient or the carbon monoxide and carbon dioxide concentration is high, it is automatically added to the methanation reactor to control the hydrogen-carbon ratio. When the tank reaches the discharge pressure, the high-purity hydrogen is discharged to form a high-purity hydrogen product.

[0071] A second aspect of the present invention provides an application of the aforementioned method in extracting helium and preparing hydrogen from industrial tail gas.

[0072] The present invention will be described in detail below through examples.

[0073] In the following examples and comparative examples:

[0074] The gas composition (volume fraction) parameters were measured by gas chromatography detection method;

[0075] 13X molecular sieve: Zibo Henghuan Aluminum Co., Ltd., synthetic zeolite sodium X (13X), 13XAGP molecular sieve HHMM-304;

[0076] Hydrogen storage alloy: Xi'an Qiyue Mg-Ni binary hydrogen storage alloy;

[0077] Porous ceramic palladium copper alloy membrane: Yiwu Ruisheng New Material Technology Co., Ltd., customized.

[0078] Example 1

[0079] This embodiment is intended to illustrate the extraction of helium and the preparation of hydrogen using the method of the present invention.

[0080] A certain helium-containing chemical tail gas S1 includes 19.8% helium, 38.3% methane, 3.3% nitrogen, 3.4% carbon dioxide, 29.0% hydrogen and 6.0% carbon monoxide; wherein, the intake flow rate of the tail gas composition is normalized.

[0081] according to Figure 1 The present invention provides a flow chart of a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology. The method comprises the following steps:

[0082] (1) The raw gas S1 is subjected to a methanogenic reaction in a methanogenic reaction unit, wherein hydrogen, carbon dioxide, and carbon monoxide react and are mostly removed to generate a mixed gas containing water, methane, a small amount of unreacted hydrogen, and trace amounts of carbon dioxide, carbon monoxide, and other gases that do not participate in the reaction. The mixed gas is subjected to heat exchange to form S2;

[0083] Among them, H2 / (3CO+4CO2) in the raw gas is 0.91, and H2 / (3CO+4CO2) in the mixed gas is adjusted to 1.1 after hydrogen supplementation;

[0084] The methanation process uses a circulating multi-stage fixed bed process, and the methanation temperature is controlled at 600°C;

[0085] (2) After deep dehydration and carbon dioxide removal, S2 forms a mixed gas S3 which enters the polymer organic separation membrane unit. Most of the helium and hydrogen pass through the membrane to form permeate gas S4. The residual gas S5 that does not pass through the membrane mainly contains methane and nitrogen and can be reused.

[0086] The membrane set in the polymer organic separation membrane unit is the PI separation membrane of Beijing Institute of Chemical Industry (polyimide-based hollow fiber membrane prepared in Example 1 of CN115501758B), with a temperature of 80°C and an operating pressure of 3.5MPa.

[0087] (3) S4 is deeply dehydrogenated through a helium refinement unit to form high-purity helium S6. The separated high-purity hydrogen S7 is stored in a hydrogen storage tank, part of which is sent to a methanation reaction unit for hydrogen replenishment, and most of it is collected to obtain high-purity hydrogen S8;

[0088] Among them, the helium refinement unit selects alloy adsorption technology and palladium alloy membrane separation technology, selects Mg2Ni as the hydrogen adsorbent, controls the adsorption temperature at 300℃, the pressure at 10Mpa, and the airspeed at 25m 3 / m 3 h; desorption temperature 400℃, desorption pressure 0.5Mpa;

[0089] A porous ceramic palladium-copper alloy membrane with a thickness of 20 μm was selected as the hydrogen separation membrane, the gas temperature was controlled at 500 °C, and the pressure was controlled at 5 MPa;

[0090] The treatment results are shown in Table 1-1 and Table 1-2, wherein the helium concentration is >99.999%, and the yield is >90%; the hydrogen concentration is >99.999%, and the yield is >98%; the methane-rich gas concentration is >90%, and the methane yield is >124%.

[0091] Table 1-1

[0092] No.\Composition% Helium Methane Nitrogen carbon dioxide hydrogen water Carbon monoxide flow 0.1982 0.3834 0.0332 0.0342 0.2906 0.0000 0.0603 Raw gas S1 19.8241 38.3411 3.3247 3.4151 29.0616 0.0000 6.0334 flow 0.0000 0.0000 0.0000 0.0000 0.0588 0.0000 0.0000 Hydrogen Refill S9 0.0002 0.0000 0.0000 0.0000 99.9998 0.0000 0.0000 flow 0.1982 0.3834 0.0332 0.0342 0.3494 0.0000 0.0603 Mixed gas 18.7240 36.2135 3.1402 3.2256 32.9981 0.0000 5.6986 flow 0.1982 0.4778 0.0332 0.0000 0.0319 0.1286 0.0000 Methanation S2 22.7894 54.9324 3.8220 0.0016 3.6699 14.7805 0.0042 flow 0.1982 0.4778 0.0332 0.0000 0.0319 0.0001 0.0000 <![CDATA[Dehydration and CO2 removal, S3]]> 26.7398 64.4546 4.4846 0.0000 4.3061 0.0102 0.0049 flow 0.1899 0.0000 0.0000 0.0000 0.0262 0.0000 0.0000 Level 3 Penetration S4 87.8682 0.0000 0.0000 0.0000 12.1318 0.0000 0.0000 flow 0.0084 0.4778 0.0332 0.0000 0.0057 0.0001 0.0000 Membrane retentate S5 1.5927 90.9700 6.3294 0.0000 1.0867 0.0143 0.0069 flow 0.0000 0.0000 0.0000 0.0000 0.0211 0.0000 0.0000 Palladium secondary penetration 0.0004 0.0000 0.0000 0.0000 99.9996 0.0000 0.0000 flow 0.1899 0.0000 0.0000 0.0000 0.0051 0.0000 0.0000 Membrane retentate 97.3635 0.0000 0.0000 0.0000 2.6364 0.0000 0.0000 flow 0.1899 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Alloy adsorption S6 99.9999 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0051 0.0000 0.0000 Desorption S7 0.0011 0.0000 0.0000 0.0000 99.9989 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0262 0.0000 0.0000 Hydrogen storage tank S8 0.0005 0.0000 0.0000 0.0000 99.9995 0.0000 0.0000

[0093] Table 1-2

[0094] serial number concentration% Yield / Utilization % Helium 99.9999 95.7799 hydrogen 99.9995 98.0358 Methane 90.9700 124.6303

[0095] Example 2

[0096] This embodiment is intended to illustrate the extraction of helium and the preparation of hydrogen using the method of the present invention.

[0097] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0098] A certain helium-containing chemical tail gas S1 includes 15.9% helium, 45.6% methane, 3.9% nitrogen, 3.4% carbon dioxide, 26.0% hydrogen and 5.0% carbon monoxide; wherein, the intake flow rate of the tail gas composition is normalized.

[0099] according to Figure 1 The present invention provides a flow chart of a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology. The difference is that:

[0100] Among them, H2 / (3CO+4CO2) in the raw gas is 0.90, and H2 / (3CO+4CO2) in the mixed gas is adjusted to 1.1 after hydrogen supplementation;

[0101] The methanation process uses a circulating multi-stage fixed bed process, and the methanation temperature is controlled at 540°C;

[0102] Use 13X molecular sieve, adsorption pressure 3Mpa, air velocity 20m 3 / m 3 ·h.

[0103] The membrane set in the polymer organic separation membrane unit is selected from the Beijing Institute of Chemical Industry PI separation membrane (polyimide-based hollow fiber membrane prepared in Example 1 of CN115501758B), the temperature is 50°C, and the operating pressure is 5MPa;

[0104] The helium refinement unit selects alloy adsorption technology and palladium alloy membrane separation technology, selects Mg2Ni as hydrogen adsorbent, controls the adsorption temperature at 350℃, pressure at 10Mpa, and airspeed at 10m 3 / m 3 h; desorption temperature 400℃, desorption pressure 0.1Mpa;

[0105] A porous ceramic palladium-copper alloy membrane with a thickness of 20 μm was selected as the hydrogen separation membrane, the gas temperature was controlled at 310 °C, and the pressure was controlled at 4.3 MPa;

[0106] The treatment results are shown in Table 2-1 and Table 2-2, wherein the helium concentration is >99.9999%, and the yield is >90%; the hydrogen concentration is >99.999%, and the yield is >97%; the methane-rich gas concentration is >90%, and the methane yield is >118%.

[0107] Table 2-1

[0108]

[0109]

[0110] Table 2-2

[0111] serial number concentration% Yield / Utilization % Helium 99.99993 95.19013 hydrogen 99.99949 97.95570 Methane 91.18971 118.56356

[0112] Example 3

[0113] This embodiment is intended to illustrate the extraction of helium and the preparation of hydrogen using the method of the present invention.

[0114] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0115] A certain helium-containing chemical tail gas S1 includes 11.9% helium, 40.8% methane, 4.2% nitrogen, 1.9% carbon dioxide, 33.7% hydrogen and 7.2% carbon monoxide; the intake flow rate of the tail gas composition is normalized.

[0116] according to Figure 1 The present invention provides a flow chart of a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology. The difference is that:

[0117] Among them, H2 / (3CO+4CO2) in the raw gas is 1.14, and there is no need to adjust the H2 / (3CO+4CO2) ratio in the mixed gas.

[0118] The methanation process uses a circulating multi-stage fixed bed process, and the methanation temperature is controlled at 630°C;

[0119] Use 13X molecular sieve, adsorption pressure 5Mpa, air velocity 6m 3 / m 3 ·h.

[0120] The membrane set in the polymer organic separation membrane unit is selected from the Beijing Institute of Chemical Industry PI separation membrane (polyimide-based hollow fiber membrane prepared in Example 1 of CN115501758B), the temperature is 25°C, and the operating pressure is 3.5MPa;

[0121] The helium refinement unit selects alloy adsorption technology and palladium alloy membrane separation technology, selects Mg2Ni as the hydrogen adsorbent, controls the adsorption temperature at 340℃, the pressure at 6Mpa, and the airspeed at 12m 3 / m 3 h; desorption temperature 400℃, desorption pressure 0.5Mpa;

[0122] A porous ceramic palladium-copper alloy membrane with a thickness of 20 μm was selected as the hydrogen separation membrane, the gas temperature was controlled at 400 °C, and the pressure was controlled at 5 MPa;

[0123] The treatment results are shown in Tables 3-1 and 3-2, wherein the helium concentration is >99.9999% and the yield is >90%; the hydrogen concentration is >99.999% and the yield is >97%; the methane-rich gas concentration is >90% and the methane yield is >122%.

[0124] Table 3-1

[0125] No.\Composition% Helium Methane Nitrogen CO2 hydrogen water CO flow 0.1197 0.4080 0.0427 0.0195 0.3378 0.0000 0.0724 Raw gas S1 11.9659 40.8039 4.2682 1.9477 33.7781 0.0000 7.2363 flow 0.1197 0.4998 0.0427 0.0000 0.0429 0.1113 0.0000 Methanation S2 14.6565 61.2217 5.2279 0.0010 5.2603 13.6274 0.0053 flow 0.1197 0.4998 0.0427 0.0000 0.0429 0.0001 0.0000 <![CDATA[Dehydration and CO2 removal, S3]]> 16.9664 70.8706 6.0518 0.0000 6.0894 0.0157 0.0062 flow 0.1148 0.0000 0.0000 0.0000 0.0353 0.0000 0.0000 Level 3 Penetration S4 76.4691 0.0000 0.0000 0.0000 23.5309 0.0000 0.0000 flow 0.0048 0.4998 0.0427 0.0000 0.0076 0.0001 0.0000 Membrane retentate S5 0.8725 90.0391 7.6887 0.0000 1.3719 0.0199 0.0078 flow 0.0000 0.0000 0.0000 0.0000 0.0279 0.0000 0.0000 Palladium secondary penetration 0.0002 0.0000 0.0000 0.0000 99.9998 0.0000 0.0000 flow 0.1148 0.0000 0.0000 0.0000 0.0074 0.0000 0.0000 Membrane retentate 93.9594 0.0000 0.0000 0.0000 6.0405 0.0000 0.0000 flow 0.1148 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Alloy adsorption S6 99.9999 0.0000 0.0000 0.0000 0.0001 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0074 0.0000 0.0000 Desorption S7 0.0003 0.0000 0.0000 0.0000 99.9997 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0353 0.0000 0.0000 Hydrogen storage tank S8 0.0002 0.0000 0.0000 0.0000 99.9998 0.0000 0.0000

[0126] Table 3-2

[0127] serial number concentration% Yield / Utilization % Helium 99.9999 95.9520 hydrogen 99.9998 97.7453 Methane 90.0391 122.4951

[0128] Example 4

[0129] This embodiment is intended to illustrate the extraction of helium and the preparation of hydrogen using the method of the present invention.

[0130] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0131] A certain helium-containing chemical tail gas S1 includes 15.2% helium, 42.4% methane, 6.3% nitrogen, 1.8% carbon dioxide, 26.7% hydrogen and 7.3% carbon monoxide; the intake flow rate of the tail gas composition is normalized.

[0132] according to Figure 1 The present invention provides a flow chart of a method for extracting helium and producing hydrogen by coupling a methanogenic reaction with a membrane separation technology. The difference is that:

[0133] Among them, H2 / (3CO+4CO2) in the raw gas is 0.91, and after hydrogen supplementation, H2 / (3CO+4CO2) in the mixed gas is adjusted to 1.1.

[0134] The methanation process uses a circulating multi-stage fixed bed process, and the methanation temperature is controlled at 700°C;

[0135] Select 13X molecular sieve, adsorption pressure 2.6Mpa, air velocity 17m 3 / m 3 ·h.

[0136] The membrane set in the polymer organic separation membrane unit is selected from the Beijing Institute of Chemical Industry PI separation membrane (polyimide-based hollow fiber membrane prepared in Example 1 of CN115501758B), the temperature is 10°C, and the operating pressure is 4.5MPa;

[0137] The helium refinement unit selects alloy adsorption technology and palladium alloy membrane separation technology, selects Mg2Ni as the hydrogen adsorbent, controls the adsorption temperature at 320℃, pressure at 8Mpa, and airspeed at 40m 3 / m 3 h; desorption temperature 400℃, desorption pressure 0.15Mpa;

[0138] A porous ceramic palladium-copper alloy membrane with a thickness of 20 μm was selected as the hydrogen separation membrane, the gas temperature was controlled at 300 °C, and the pressure was controlled at 5 MPa;

[0139] The treatment results are shown in Tables 4-1 and 4-2, wherein the helium concentration is >99.9999% and the yield is >90%; the hydrogen concentration is >99.999% and the yield is >97%; the methane-rich gas concentration is >86% and the methane yield is >121%.

[0140] Table 4-1

[0141] No.\Composition% Helium Methane Nitrogen CO2 hydrogen water CO flow 0.1529 0.4245 0.0635 0.0181 0.2679 0.0000 0.0731 Raw gas S1 15.2889 42.4499 6.3547 1.8100 26.7852 0.0000 7.3114 flow 0.0000 0.0000 0.0000 0.0000 0.0531 0.0000 0.0000 Hydrogen Refill S9 0.0003 0.0000 0.0000 0.0000 99.9997 0.0000 0.0000 flow 0.1529 0.4245 0.0635 0.0181 0.3209 0.0000 0.0731 Mixed gas 14.5185 40.3109 6.0345 1.7188 30.4743 0.0000 6.9430 flow 0.1529 0.5157 0.0635 0.0000 0.0293 0.1093 0.0000 Methanation S2 17.5585 59.2212 7.2981 0.0008 3.3689 12.5474 0.0050 flow 0.1529 0.5157 0.0635 0.0000 0.0293 0.0001 0.0000 <![CDATA[Dehydration and CO2 removal, S3]]> 20.0763 67.7131 8.3446 0.0000 3.8520 0.0083 0.0058 flow 0.1444 0.0000 0.0000 0.0000 0.0238 0.0000 0.0000 Level 3 Penetration S4 85.8735 0.0000 0.0000 0.0000 14.1265 0.0000 0.0000 flow 0.0085 0.5157 0.0635 0.0000 0.0056 0.0001 0.0000 Membrane retentate S5 1.4339 86.8983 10.7089 0.0000 0.9409 0.0107 0.0074 flow 0.0000 0.0000 0.0000 0.0000 0.0189 0.0000 0.0000 Palladium secondary penetration 0.0003 0.0000 0.0000 0.0000 99.9997 0.0000 0.0000 flow 0.1444 0.0000 0.0000 0.0000 0.0048 0.0000 0.0000 Membrane retentate 96.7785 0.0000 0.0000 0.0000 3.2214 0.0000 0.0000 flow 0.1444 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Alloy adsorption S6 99.9999 0.0000 0.0000 0.0000 0.0001 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0048 0.0000 0.0000 Desorption S7 0.0006 0.0000 0.0000 0.0000 99.9994 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0238 0.0000 0.0000 Hydrogen storage tank S8 0.0004 0.0000 0.0000 0.0000 99.9996 0.0000 0.0000

[0142] Table 4-2

[0143] serial number concentration% Yield / Utilization % Helium 99.9999 94.4347 hydrogen 99.9996 97.9154 Methane 86.8983 121.4752

[0144] Example 5

[0145] This embodiment is intended to illustrate the extraction of helium and the preparation of hydrogen using the method of the present invention.

[0146] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0147] Among them, H2 / (3CO+4CO2) in the raw gas is 0.91, and H2 / (3CO+4CO2) in the mixed gas is adjusted to 1.23 after hydrogen supplementation;

[0148] The hydrogen content of the product is close to 0.0001% (1ppm) and is about to exceed the standard.

[0149] Table 5-1

[0150]

[0151]

[0152] Table 5-2

[0153] serial number concentration% Yield / Utilization % Helium 99.9998 93.6158 hydrogen 99.9998 95.0280 Methane 88.7732 124.6303

[0154] The treatment results are shown in Tables 5-1 and 5-2, wherein the helium concentration is >99.9999% and the yield is >90%; the hydrogen concentration is >99.999% and the yield is >95%; the methane-rich gas concentration is >88% and the methane yield is >124%.

[0155] Comparative Example 1

[0156] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0157] Adjust the mixed gas to H2 / (3CO+4CO2)=1.3.

[0158] The treatment results are shown in Table 6-1 and Table 6-2, wherein the helium concentration is >99.999%, which is lower than the helium purity in Example 1. Although it reaches the 5N level, the hydrogen content of 3ppm is higher than 1ppm and does not meet the high-purity helium standard. Excessive hydrogen will increase the separation burden and dehydrogenation burden of the rear membrane unit, resulting in poor results.

[0159] Table 6-1

[0160] No.\Composition% Helium Methane Nitrogen CO2 hydrogen water CO flow 0.1982 0.3834 0.0332 0.0342 0.2906 0.0000 0.0603 Raw gas S1 19.8241 38.3411 3.3247 3.4151 29.0616 0.0000 6.0334 flow 0.0000 0.0000 0.0000 0.0000 0.1858 0.0000 0.0000 Hydrogen Refill S9 0.0003 0.0000 0.0000 0.0000 99.9997 0.0000 0.0000 flow 0.1982 0.3834 0.0332 0.0342 0.4764 0.0000 0.0603 Mixed gas 16.7180 32.3337 2.8038 2.8800 40.1764 0.0000 5.0881 flow 0.1982 0.4778 0.0332 0.0000 0.1590 0.1286 0.0000 Methanation S2 19.8852 47.9321 3.3350 0.0014 15.9457 12.8969 0.0036 flow 0.1982 0.4778 0.0332 0.0000 0.1590 0.0001 0.0000 <![CDATA[Dehydration and CO2 removal, S3]]> 22.8274 55.0240 3.8284 0.0000 18.3050 0.0111 0.0042 flow 0.1903 0.0000 0.0000 0.0000 0.1308 0.0000 0.0000 Level 3 Penetration S4 59.2586 0.0000 0.0000 0.0000 40.7414 0.0000 0.0000 flow 0.0080 0.4778 0.0332 0.0000 0.0281 0.0001 0.0000 Membrane retentate S5 1.4545 87.3045 6.0744 0.0000 5.1424 0.0175 0.0066 Palladium secondary penetration 0.0001 0.0000 0.0000 0.0000 99.9999 0.0000 0.0000 flow 0.0001 0.0000 0.0000 0.0000 0.0126 0.0000 0.0000 Membrane retentate 87.1707 0.0000 0.0000 0.0000 12.8292 0.0000 0.0000 flow 0.1903 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Alloy adsorption S6 99.9997 0.0000 0.0000 0.0000 0.0003 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0280 0.0000 0.0000 Desorption S7 0.0003 0.0000 0.0000 0.0000 99.9997 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.1308 0.0000 0.0000 Hydrogen storage tank S8 0.0001 0.0000 0.0000 0.0000 99.9999 0.0000 0.0000

[0161] Table 6-2

[0162] serial number concentration% Yield / Utilization % Helium 99.9997 95.9840 hydrogen 99.9999 90.3148 Methane 87.3045 124.6303

[0163] Comparative Example 2

[0164] Helium is extracted and hydrogen is prepared in the same manner as in Example 4, except that:

[0165] Eliminate hydrogen storage tank reflux regulation and directly use methanogenization.

[0166] The treatment results are shown in Table 7-1 and Table 7-2. Since H2 / (3CO+4CO2)=0.91 in the mixed gas, the direct methanation without adjusting the reflux of the hydrogen storage tank leads to the failure of carbon monoxide and carbon dioxide to react fully and easily produces side reactions to form carbon deposits, which is not conducive to the long-term stable operation of the equipment. The concentrations of helium and methane-rich gas are significantly reduced, and the methane-rich gas cannot reach 85%. The yields of helium, hydrogen, and methane are all lower than those in Example 4. The direct methanation effect without adjusting the hydrogen-carbon ratio is very poor.

[0167] Table 7-1

[0168]

[0169]

[0170] Table 7-2

[0171] serial number concentration% Yield / Utilization % Helium 99.9997 93.3064 hydrogen 99.9998 96.9926 Methane 83.5997 116.8044

[0172] Comparative Example 3

[0173] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0174] The chemical tail gas S1 contains 3% helium, 10% methane, 63% nitrogen, 4% carbon dioxide, 14% hydrogen and 6% carbon monoxide. Other conditions are the same as those in Example 1.

[0175] The processing results are shown in Table 8-1 and Table 8-2, among which, the product helium concentration cannot reach the 5N level, the hydrogen content of 4ppm does not meet the ultra-pure helium standard, the nitrogen concentration in the methane-rich gas is too high and the methane concentration is greatly reduced, and the helium and hydrogen recovery rates are both lower than those in Example 1. Due to the low hydrogen concentration and the increase in the mixing volume of the storage tank, the methanation effect is very poor.

[0176] Table 8-1

[0177] No.\Composition% Helium Methane Nitrogen CO2 hydrogen water CO flow 0.0300 0.1000 0.6300 0.0400 0.1400 0.0000 0.0600 Raw gas S1 3.0000 10.0000 63.0000 4.0000 14.0000 0.0000 6.0000 flow 0.0000 0.0000 0.0000 0.0000 0.2340 0.0000 0.0000 Hydrogen Refill S9 0.0004 0.0000 0.0000 0.0000 99.9996 0.0000 0.0000 flow 0.0300 0.1000 0.6300 0.0400 0.3740 0.0000 0.0600 Mixed gas 2.4312 8.1037 51.0534 3.2415 30.3079 0.0000 4.8622 flow 0.0300 0.1999 0.6300 0.0000 0.0342 0.1399 0.0000 Methanation S2 2.9011 19.3354 60.9223 0.0015 3.3045 13.5317 0.0035 flow 0.0300 0.1999 0.6300 0.0000 0.0342 0.0001 0.0000 <![CDATA[Dehydration and CO2 removal, S3]]> 3.3547 22.3587 70.4481 0.0000 3.8212 0.0134 0.0040 flow 0.0285 0.0000 0.0000 0.0000 0.0278 0.0000 0.0000 Level 3 Penetration S4 50.5915 0.0000 0.0004 0.0000 49.4080 0.0000 0.0000 flow 0.0015 0.1999 0.6300 0.0000 0.0064 0.0001 0.0000 Membrane retentate S5 0.1807 23.8610 75.1817 0.0000 0.7581 0.0143 0.0043 flow 0.0000 0.0000 0.0000 0.0000 0.0221 0.0000 0.0000 Palladium secondary penetration 0.0001 0.0000 0.0000 0.0000 99.9999 0.0000 0.0000 flow 0.0285 0.0000 0.0000 0.0000 0.0057 0.0000 0.0000 Membrane retentate 83.3434 0.0000 0.0007 0.0000 16.6558 0.0000 0.0000 flow 0.0285 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Alloy adsorption S6 99.9987 0.0000 0.0009 0.0000 0.0004 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0057 0.0000 0.0000 Desorption S7 0.0002 0.0000 0.0000 0.0000 99.9998 0.0000 0.0000 flow 0.0000 0.0000 0.0000 0.0000 0.0278 0.0000 0.0000 Hydrogen storage tank S8 0.0001 0.0000 0.0000 0.0000 99.9999 0.0000 0.0000

[0178] Table 8-2

[0179] serial number concentration% Yield / Utilization % Helium 99.9987 94.9533 hydrogen 99.9999 95.4625 Methane 23.8610 199.9480

[0180] Comparative Example 4

[0181] Helium is extracted and hydrogen is prepared in the same manner as in Example 1, except that:

[0182] No methanogenic dehydrogenation unit is provided.

[0183] The treatment results are shown in Table 9-1 and Table 9-2. The carbon monoxide and carbon dioxide contents in the raw gas are relatively high and cannot be effectively removed by membrane separation alone. The helium products reach 4 and 5 ppm respectively. Since the dehydrogenation burden of the alloy adsorbent palladium membrane unit is too heavy, the dehydrogenation effect is not good. The hydrogen content in the product helium reaches 3 ppm. Finally, the helium concentration cannot reach the 5N level. The concentration of methane-rich gas is only 70%, of which the carbon monoxide and carbon dioxide contents are 11% and 5 ppm, and the hydrogen content reaches 10%, which cannot meet the recovery standard and causes waste of hydrogen resources.

[0184] Table 9-1

[0185]

[0186]

[0187] Table 9-2

[0188] serial number concentration% Yield / Utilization % Helium 99.9988 93.5643 hydrogen 99.9999 80.2196 Methane 70.0601 99.999

[0189] In summary, the high-purity helium concentration finally produced by the present invention can reach 99.999%, and the yield is greater than 90%; the methane concentration can reach >85%; the high-purity hydrogen concentration can reach 99.999%, and the yield is greater than 90%, thereby increasing considerable economic benefits for chemical plants.

[0190] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for extracting helium and producing hydrogen by coupling methanation reaction with membrane separation technology, characterized in that: The method includes: (1) subjecting a first mixed gas of a feed gas and optionally supplemented hydrogen to a methanogenic reaction unit to remove most of the hydrogen to obtain a second mixed gas; wherein the hydrogen-to-carbon ratio in the first mixed gas is controlled to meet the following conditions: H2 / (4CO2+3CO)≥1; (2) subjecting the second mixed gas to dehydration and CO2 removal treatment and then passing through a membrane separation unit to obtain a permeate gas containing helium and hydrogen; (3) deep dehydrogenating the permeate gas through a helium refinement unit to obtain high-purity helium; and collecting the hydrogen removed by the helium refinement unit to prepare hydrogen.

2. The method according to claim 1, wherein: 1.25≥H2 / (4CO2+3CO)≥1.

3. The method according to claim 1 or 2, wherein: The separation membranes provided in the membrane separation unit are each made of one or more of polysulfone, polyethersulfone, polyimide, polypropylene, polyethylene, synthetic resin, polyvinylidene fluoride, polytetrafluoroethylene, polyetheretherketone, polybenzimidazole, block copolymer, cellulose acetate membrane, polycarbonate membrane, polymethyl methacrylate membrane, silicon dioxide membrane, zeolite molecular sieve membrane, carbon molecular sieve membrane and metal organic framework material; And / or, the separation membrane is one or more of a rolled membrane, a hollow fiber membrane, a flat membrane and a tubular membrane.

4. The method according to claim 3, wherein: The separation membrane is a polyimide hollow fiber membrane.

5. The method according to any one of claims 1 to 4, wherein: After the methanation reaction, the conversion rate of hydrogen is greater than 99%, and the removal rates of carbon monoxide and carbon dioxide are greater than 99.9%.

6. The method according to any one of claims 1 to 5, wherein: The total concentration of H2 and He in the permeate gas is greater than 90%; And / or, the total yield of H2 and He in the permeate gas is greater than 85%.

7. The method according to any one of claims 1 to 6, wherein: The raw gas is factory exhaust gas; Preferably, the feed gas contains one or more of methane, hydrogen, helium, nitrogen, carbon monoxide and carbon dioxide; Preferably, based on the total volume of the raw gas, the content of hydrogen is 20-35% by volume; More preferably, based on the total volume of the raw gas, the content of hydrogen is 20-35% by volume, the content of methane is 20-50% by volume, the content of helium is 10-20% by volume, the content of nitrogen is 0-10% by volume, the content of carbon monoxide is 5-10% by volume, and the content of carbon dioxide is 1-5% by volume; More preferably, the total content of carbon monoxide and carbon dioxide is less than 10% by volume.

8. The method according to claim 1, wherein: The conditions of the methanation reaction include: a temperature of 500-700°C; And / or, the inlet gas temperature in the methanation reaction is greater than 300°C.

9. The method according to claim 1, wherein: The membrane separation conditions include: membrane separation temperature of 0-120°C, membrane pressure of 0.1-10MPa; Preferably, the membrane separation temperature is 25-80°C and the transmembrane pressure is 2-5 MPa.

10. The method according to claim 1, wherein: The helium refinement unit includes alloy adsorption and / or palladium alloy membrane separation; Preferably, the palladium membrane provided in the palladium alloy membrane separation is selected from one or more of a tubular palladium membrane, a porous carrier composite membrane and an alloy membrane; And / or, the conditions for the palladium alloy membrane separation include: the palladium membrane dehydrogenation temperature is 300-500° C., the palladium membrane dehydrogenation pressure is 1-50 MPa, preferably, the pressure is 1-5 MPa.

11. The method according to claim 1 or 10, wherein: The adsorbent used for alloy adsorption is selected from one or more of rare earth hydrogen storage alloys, titanium hydrogen storage alloys, zirconium hydrogen storage alloys, vanadium hydrogen storage alloys and magnesium hydrogen storage alloys; And / or, the conditions for alloy adsorption include: adsorption temperature of 300-400°C, adsorption pressure of 2.4-40Mpa; desorption temperature of 300-400°C, desorption pressure of 0.1-2.4Mpa; bed space velocity of 1m 3 / m 3 ·h-10000m 3 / m 3 ·h; Preferably, the conditions for alloy adsorption include: adsorption temperature of 300-350°C, adsorption pressure of 5-10Mpa; desorption temperature of 400°C, desorption pressure of 0.1-0.5Mpa; bed space velocity of 10m 3 / m 3 ·h-50m 3 / m 3 ·h.

12. The method according to any one of claims 1 to 11 is used for extracting helium and preparing hydrogen from industrial tail gas.

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