Method, system and application for purifying helium

Abstract

The present application relates to the field of helium purification process, and discloses a method, system and application for purifying helium.The method comprises: in the presence of a catalyst, catalytically reacting raw material gas and optionally oxygen, performing first membrane separation, targeted dehydrogenation and second membrane separation to obtain helium and helium-lean gas, and returning the helium-lean gas to step S2 for first membrane separation; or in the presence of a catalyst, catalytically reacting raw material gas and optionally oxygen, performing targeted dehydrogenation, first membrane separation and second membrane separation to obtain helium and helium-lean gas, and returning the helium-lean gas to step S2 for first membrane separation; the gas pressure P1 on the inlet side of the first membrane separation is not greater than 10 MPa; and the gas pressure P2 on the inlet side of the second membrane separation is not less than 0.5 MPa.The method has high recovery rate, and by setting a multi-step membrane separation process and cooperatively using targeted dehydrogenation technology instead of pressure swing adsorption, the yield and purity of helium can be improved under the premise of reducing energy consumption.

Description

Technical Field

[0001] This invention relates to helium purification processes, specifically to a method, system, and application for purifying helium. Background Technology

[0002] Helium is a special gas with low density, low boiling point, and inert properties, often found alongside natural gas. Due to its unique properties, helium plays an indispensable role in many fields, including aerospace, deep-sea diving, medical imaging, superconducting materials, semiconductors, hard drives, and cooling nuclear reactors. With economic development, the demand for helium is growing rapidly. To meet the demand for helium resources, there is an urgent need to develop methods for producing high-purity helium with low energy consumption.

[0003] Natural gas helium extraction technologies are mainly divided into non-cryogenic methods and cryogenic methods. Non-cryogenic methods include physical adsorption, solvent absorption, membrane separation, and pressure swing adsorption, while cryogenic methods are also known as deep cryogenic processes. Currently, cryogenic processes are the most commonly used industrial helium extraction method, with approximately 90% of helium extracted through this method. However, using cryogenic processes alone for helium purification still suffers from problems such as low operational flexibility, high equipment investment, and high energy consumption, making it uncompetitive in terms of economic efficiency. Furthermore, cryogenic processes struggle to remove hydrogen from the feed gas, making it difficult to guarantee product concentration. Therefore, there is an urgent need to develop superior helium purification methods.

[0004] Membrane separation utilizes the differences in permeability of natural gas components during dissolution, diffusion, and desorption, driven by the pressure difference across a membrane, to achieve helium separation. Membrane separation is simple to operate, consumes little energy, and has low construction and operating costs, making it highly competitive. Designing helium separation membranes with high helium selectivity and high gas flux is of great significance for achieving economical helium extraction from natural gas, reducing dependence on helium imports, and realizing autonomy in helium production and utilization. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of high energy consumption, low helium yield and purity in the existing technology, and to provide a method, system and application for purifying helium. The method is simple to operate, has low energy consumption, and can improve the purity of helium while ensuring a high helium yield.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for purifying helium, characterized in that the method comprises:

[0007] S1. In the presence of a catalyst, the feed gas and, optionally, oxygen, undergo a catalytic reaction to obtain a first mixed gas.

[0008] S2. Perform first membrane separation on the first mixed gas to obtain a second mixed gas and hydrogen-containing helium gas;

[0009] S3. In the presence of a targeted dehydrogenation membrane, hydrogen-containing helium gas is subjected to targeted dehydrogenation to obtain crude helium gas and hydrogen gas.

[0010] S4. Perform a second membrane separation on the crude helium gas to obtain helium gas and helium-lean gas. The helium-lean gas is then returned to step S2 for the first membrane separation; or...

[0011] a. In the presence of a catalyst, the feed gas and, optionally, oxygen, undergo a catalytic reaction to obtain a first mixed gas;

[0012] b. In the presence of a targeted dehydrogenation membrane, hydrogen-containing helium gas is subjected to targeted dehydrogenation to obtain a second mixed gas and hydrogen-containing helium gas;

[0013] c. Perform a first membrane separation on the first mixed gas to obtain crude helium and hydrogen;

[0014] d. The crude helium gas is subjected to a second membrane separation to obtain helium gas and helium-lean gas. The helium-lean gas is returned to step S2 for the first membrane separation.

[0015] Wherein, the gas pressure P1 on the inlet side of the first membrane separation is not greater than 10MPa;

[0016] The gas pressure P2 on the inlet side of the second membrane separator is not less than 0.5 MPa.

[0017] A second aspect of the present invention provides a system for purifying helium, characterized in that the system comprises a catalytic dehydrogenation unit, a membrane separation unit, a targeted dehydrogenation unit, and a purification unit connected in sequence.

[0018] The catalytic dehydrogenation unit is used to catalytically react the feed gas to obtain a first mixed gas;

[0019] The membrane separation unit is used to perform a first membrane separation on the first mixed gas from the catalytic dehydrogenation unit to obtain a second mixed gas and hydrogen-containing helium gas.

[0020] The targeted dehydrogenation unit is used to target the dehydrogenation of hydrogen-containing helium gas from the membrane separation unit to obtain crude helium gas and hydrogen gas.

[0021] The targeted dehydrogenation unit is equipped with a targeted dehydrogenation membrane;

[0022] The refining unit is used to refine the crude helium gas from the targeted dehydrogenation unit through a second membrane separation to obtain helium gas and helium-lean gas.

[0023] The lean helium gas is returned to the first membrane separator; or...

[0024] The catalytic dehydrogenation unit is used to catalytically react the feed gas to obtain a first mixed gas;

[0025] The targeted dehydrogenation unit is used to target the dehydrogenation of hydrogen-containing helium gas from the membrane separation unit to obtain a second mixed gas and hydrogen-containing helium gas.

[0026] The membrane separation unit is used to perform a first membrane separation on the first mixed gas from the catalytic dehydrogenation unit to obtain crude helium and hydrogen.

[0027] The targeted dehydrogenation unit is equipped with a targeted dehydrogenation membrane;

[0028] The refining unit is used to refine the crude helium gas from the targeted dehydrogenation unit through a second membrane separation to obtain helium gas and helium-lean gas.

[0029] The depleted helium gas is returned to the first membrane separator.

[0030] A third aspect of the present invention provides an application of the method described in the first aspect and / or the system described in the second aspect of the present invention in at least one of the fields of energy, medicine and chemical industry.

[0031] Through the above technical solutions, the method, system and application for purifying helium provided by the present invention achieve the following beneficial effects: the method for purifying helium provided by the present invention operates stably, under mild conditions and has a high recovery rate. By setting up a multi-step membrane separation process and synergistically utilizing targeted dehydrogenation technology to replace pressure swing adsorption, the yield and purity of helium can be improved while reducing energy consumption, and high-purity hydrogen can be obtained at the same time. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the process for purifying helium in Embodiment 1 of the present invention. Detailed Implementation

[0033] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The first aspect of the present invention provides a method for purifying helium, characterized in that the method comprises:

[0035] S1. In the presence of a catalyst, the feed gas and, optionally, oxygen, undergo a catalytic reaction to obtain a first mixed gas.

[0036] S2. Perform first membrane separation on the first mixed gas to obtain a second mixed gas and hydrogen-containing helium gas;

[0037] S3. In the presence of a targeted dehydrogenation membrane, hydrogen-containing helium gas is subjected to targeted dehydrogenation to obtain crude helium gas and hydrogen gas.

[0038] S4. Perform a second membrane separation on the crude helium gas to obtain helium gas and helium-lean gas. The helium-lean gas is then returned to step S2 for the first membrane separation; or...

[0039] a. In the presence of a catalyst, the feed gas and, optionally, oxygen, undergo a catalytic reaction to obtain a first mixed gas;

[0040] b. In the presence of a targeted dehydrogenation membrane, hydrogen-containing helium gas is subjected to targeted dehydrogenation to obtain a second mixed gas and hydrogen-containing helium gas;

[0041] c. Perform a first membrane separation on the first mixed gas to obtain crude helium and hydrogen;

[0042] d. The crude helium gas is subjected to a second membrane separation to obtain helium gas and helium-lean gas. The helium-lean gas is returned to step S2 for the first membrane separation.

[0043] Wherein, the gas pressure P1 on the inlet side of the first membrane separation is not greater than 10MPa;

[0044] The gas pressure P2 on the inlet side of the second membrane separator is not less than 0.5 MPa.

[0045] The method for purifying helium provided in this invention is stable, operates under mild conditions, and has a high recovery rate. Traditional cryogenic techniques require temperatures below -200°C to separate helium from gases such as methane and nitrogen, resulting in extremely high energy consumption and stringent requirements for the cold source. Furthermore, the presence of hydrogen in the feed gas leads to very low condensation temperatures for both hydrogen and helium, resulting in poor separation and difficulty in obtaining high-purity helium.

[0046] This invention eliminates the need for cryogenic operation. Instead of pressure swing adsorption (PSA) dehydrogenation, it utilizes a catalytic reaction-based targeted dehydrogenation method, which removes a large amount of hydrogen from the feed gas while reducing energy consumption. Furthermore, it incorporates multi-stage membrane separation processes for efficient separation, removing most impurities such as methane, nitrogen, oxygen, and carbon dioxide. A multi-step membrane separation process has also been developed, with a second membrane separation step for further purification to obtain a high-yield, high-purity helium product, while simultaneously producing high-purity hydrogen.

[0047] In this invention, there is no particular restriction on the order of steps S2 and S3. The first membrane separation in step S2 can be performed first, or the targeted dehydrogenation in step S3 can be performed first. From a cost-saving perspective, it is preferable to perform the first membrane separation in step S2 first, followed by the targeted dehydrogenation in step S3.

[0048] In this invention, in order to further improve the purity and yield of helium, the method further includes drying the first mixed gas.

[0049] In this invention, there are no special requirements for the drying method; it can be a conventional drying method in the art, and those skilled in the art can make adjustments as needed.

[0050] In this invention, the gas composition of the feed gas is not specifically limited; it is a helium-rich gas, and the method of this invention has universal applicability. Generally, the feed gas may include helium resources such as natural gas and associated gas from oil fields.

[0051] In this invention, the raw material gas contains helium, nitrogen, methane, hydrogen, and carbon dioxide.

[0052] Furthermore, in this invention, there is no specific limitation on the content of gas components in the raw material gas. For example, in this invention, based on the total volume of the raw material gas, the helium content is 5-60% by volume, preferably, based on the total volume of the raw material gas, the helium content is 15-60% by volume.

[0053] According to the present invention, the raw material gas also contains optional impurities such as oxygen and water, and based on the total volume of the raw material gas, the oxygen content is 0-8% by volume and the water content is 0-2% by volume.

[0054] According to the present invention, in step S1, the amount of oxygen introduced is such that, based on the total amount of the raw material gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:1-4.

[0055] In this invention, when the molar ratio of hydrogen to oxygen meets the above-mentioned range, the catalytic reaction can proceed more thoroughly, further improving the purity of helium.

[0056] In this invention, there is no particular limitation on the amount of oxygen introduced, as long as the molar ratio of hydrogen to oxygen is 1:1-4 based on the total amount of the raw material gas and the oxygen. For example, in this invention, the volume ratio of the oxygen introduced to the raw material gas is 2-12:100.

[0057] In this invention, when the oxygen content in the raw material gas is sufficient, and the oxygen:hydrogen volume ratio is not less than 1:1 based on the total volume of the raw material gas and the oxygen, then no additional oxygen needs to be added; if the raw material gas contains no oxygen or has a low oxygen content, then additional oxygen needs to be added to meet the above range in order to ensure the smooth progress of the catalytic reaction.

[0058] According to the present invention, in step S1, the amount of oxygen introduced is such that, based on the total amount of the raw material gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:1-2.

[0059] According to the present invention, the conditions for the catalytic reaction include a temperature of 60-120°C.

[0060] In this invention, the conditions for the catalytic reaction satisfy the above-mentioned range, which enables the reaction to be more complete, improves the purification efficiency of the process, and further increases the helium yield.

[0061] In this invention, there is no particular limitation on the time of the catalytic reaction, as long as the chemical equilibrium point of the catalytic reaction is reached.

[0062] According to the present invention, the catalyst is a noble metal catalyst.

[0063] In this invention, the precious metal is selected from at least one of Pt, Pd, Rh, Ru and Au.

[0064] In this invention, the first membrane separation is achieved by utilizing the differences in permeability of each component in the raw gas during dissolution, diffusion, and desorption processes, driven by the pressure difference across the separation membrane, to separate helium gas.

[0065] According to the present invention, the conditions for the first membrane separation include: the gas pressure on the inlet side P1 > the gas pressure on the permeate side.

[0066] In this invention, when the gas pressure P1 on the inlet side is greater than the gas pressure on the permeation side, the separation efficiency of the first mixed gas can be higher, further improving the purity of helium. It also has the advantages of simple operation, low energy consumption, and low equipment construction and operating costs.

[0067] According to the present invention, the inlet gas pressure P1 of the first membrane separator is 0.5-10 MPa, more preferably 1-10 MPa.

[0068] According to the present invention, the first membrane separation is a multi-stage membrane separation.

[0069] In this invention, the multi-stage membrane separation can further improve the purity of helium.

[0070] In this invention, the multi-stage membrane separation is generally designed using the principle of increasing or decreasing pressure gradient, thereby reducing the cost of gas pressurization.

[0071] Furthermore, the combination of multi-stage membrane separation and targeted dehydrogenation membrane technology enables the simultaneous production of high-purity helium and high-purity hydrogen.

[0072] According to the present invention, the first membrane separation stage is 1-5 stages.

[0073] According to the present invention, the first membrane separation is carried out in the presence of a separation membrane selected from a flat sheet membrane, a hollow fiber membrane, and a tubular membrane.

[0074] In this invention, the first membrane separation is performed using a separation membrane selected from the above-mentioned types, which can further improve the separation efficiency and increase the purity of helium.

[0075] According to the present invention, the type of separation membrane is selected from at least one of homogeneous membranes, heterogeneous membranes, and composite membranes.

[0076] In this invention, the material of the separation membrane is not specifically required. For example, it can be one or more of the following: polysulfone, polyethersulfone, polyimide, polypropylene, polyethylene, synthetic resin, polyvinylidene fluoride, polytetrafluoroethylene, polyether ether ketone, polybenzimidazole (PBI), polydimethylsiloxane, block copolymer, cellulose acetate membrane, polycarbonate membrane, polymethyl methacrylate membrane, silica membrane, zeolite molecular sieve membrane, carbon molecular sieve membrane, and metal-organic framework (MOF) materials.

[0077] According to the present invention, the method for preparing the separation membrane is selected from at least one of thermally induced phase separation, solution-induced phase separation, melt stretching, interfacial polymerization, coating polymerization, and in-situ polymerization.

[0078] In this invention, the hydrogen content in the hydrogen-containing helium gas meets the above-mentioned range, which can improve the purity of helium gas while further improving the purity of hydrogen gas.

[0079] According to the present invention, the conditions for targeted dehydrogenation include: an operating temperature of 150-500°C and an operating pressure of 0.5-10 MPa.

[0080] In this invention, the targeted dehydrogenation conditions meet the above-mentioned range, which enables hydrogen molecules to better permeate the targeted dehydrogenation membrane, further improves the purity of helium, and effectively captures hydrogen, resulting in a hydrogen product with a purity of 99.99% or higher.

[0081] Furthermore, when the operating pressure meets the above range, the pressure difference across the targeted dehydrogenation membrane can be 0.01-1 MPa, which can further improve the dehydrogenation efficiency while ensuring stable process operation.

[0082] Furthermore, the conditions for targeted dehydrogenation include: an operating temperature of 200-500℃ and an operating pressure of 2-10MPa.

[0083] According to the present invention, the hydrogen permeation rate of the targeted dehydrogenation membrane is 0.02-0.3 mL / (cm²). 2 ·s).

[0084] In this invention, the inventors discovered that when the hydrogen permeation rate of the targeted dehydrogenation membrane meets the above-mentioned range, it can simultaneously improve the purity of helium and hydrogen.

[0085] In this invention, the change in hydrogen permeation rate is positively correlated with the changes in operating temperature and operating pressure.

[0086] Furthermore, the hydrogen permeation rate of the targeted dehydrogenation membrane is 0.1-0.3 mL / (cm²). 2 ·s).

[0087] Furthermore, the targeted dehydrogenation membrane is made of a palladium-yttrium alloy.

[0088] In this invention, the type of separation membrane used in the second membrane separation is the same as that used in the first membrane separation, and will not be described again here.

[0089] According to the present invention, the operating conditions for the second membrane separation include: the gas pressure on the inlet side P2 > the gas pressure on the permeate side.

[0090] In this invention, when the gas pressure P2 on the inlet side is greater than the gas pressure on the permeation side, the separation efficiency of the first mixed gas can be higher, further improving the purity of helium.

[0091] According to the present invention, the gas pressure P2 on the intake side is not greater than 10 MPa, preferably 0.5-10 MPa, and more preferably 1-10 MPa.

[0092] One specific embodiment of the present invention is as follows: Figure 1 As shown, it includes:

[0093] S1. In the presence of a precious metal catalyst, the feed gas undergoes a catalytic reaction at 60-120℃ to obtain the first mixed gas;

[0094] S2. After drying the first mixed gas, perform 1-5 stages of first membrane separation, wherein the pressure of the gas on the inlet side of each stage of first membrane separation, P1-1-P1-5, is independently 0.5-10MPa, to obtain the second mixed gas and hydrogen-containing helium gas.

[0095] S3. In the presence of a targeted dehydrogenation membrane, hydrogen-containing helium gas is subjected to targeted dehydrogenation at 150-500℃ and 0.5-10MPa to obtain crude helium gas and hydrogen gas.

[0096] S4. The crude helium gas is subjected to a second membrane separation, wherein the pressure P2 of the inlet side body is 0.5-10MPa, to obtain helium gas and helium-lean gas. The helium-lean gas is returned to step S2 for the first membrane separation.

[0097] A second aspect of the present invention provides a system for purifying helium, characterized in that the system comprises a catalytic dehydrogenation unit, a membrane separation unit, a targeted dehydrogenation unit, and a purification unit connected in sequence.

[0098] The catalytic dehydrogenation unit is used to contact the feed gas with oxygen to carry out a catalytic reaction to obtain a first mixed gas.

[0099] The membrane separation unit is used to perform a first membrane separation on the first mixed gas from the catalytic dehydrogenation unit to obtain a second mixed gas and hydrogen-containing helium gas.

[0100] The targeted dehydrogenation unit is used to target the dehydrogenation of hydrogen-containing helium gas from the membrane separation unit to obtain crude helium gas and hydrogen gas.

[0101] The targeted dehydrogenation unit is equipped with a targeted dehydrogenation membrane;

[0102] The refining unit is used to refine the crude helium gas from the targeted dehydrogenation unit through a second membrane separation to obtain helium gas and helium-lean gas.

[0103] The lean helium gas is returned to the first membrane separator; or...

[0104] The catalytic dehydrogenation unit is used to catalytically react the feed gas to obtain a first mixed gas;

[0105] The targeted dehydrogenation unit is used to target the dehydrogenation of hydrogen-containing helium gas from the membrane separation unit to obtain a second mixed gas and hydrogen-containing helium gas.

[0106] The membrane separation unit is used to perform a first membrane separation on the first mixed gas from the catalytic dehydrogenation unit to obtain crude helium and hydrogen.

[0107] The targeted dehydrogenation unit is equipped with a targeted dehydrogenation membrane;

[0108] The refining unit is used to refine the crude helium gas from the targeted dehydrogenation unit through a second membrane separation to obtain helium gas and helium-lean gas.

[0109] The depleted helium gas is returned to the first membrane separator.

[0110] In this invention, the type of raw material gas and the volume ratio of the raw material gas to the oxygen are the same as in the first aspect of this invention, and will not be repeated here.

[0111] In this invention, the conditions for the first membrane separation, the second membrane separation, and the targeted dehydrogenation are consistent with the conditions of the first aspect of this invention, and will not be repeated here.

[0112] A third aspect of the present invention provides an application of the method described in the first aspect and / or the system described in the second aspect of the present invention in at least one of the fields of energy, medicine and chemical industry.

[0113] The present invention will be described in detail below through embodiments. In the following embodiments,

[0114] The volume fraction of gas was measured using a gas analyzer.

[0115] The gas flow rate is measured by a gas flow meter;

[0116] The helium recovery rate is calculated as (outlet helium concentration * outlet flow rate) / (inlet helium concentration * inlet flow rate).

[0117] Example 1

[0118] S1. In the presence of Pb catalyst, the feed gas undergoes a catalytic reaction at 106°C (the oxygen content in the feed gas meets the requirements of the catalytic reaction, and the molar ratio of oxygen to hydrogen is 1.5:1, so no additional oxygen is required) to obtain the first mixed gas.

[0119] S2. After drying the first mixed gas, a second-stage first membrane separation is performed under the same conditions in the presence of a polysulfone hollow fiber membrane. During the first-stage first membrane separation, the pressure P1-1 of the gas on the inlet side of the separation membrane is 3 MPa.

[0120] During the first membrane separation in stage 2, the pressure P1-2 of the gas on the inlet side of the separation membrane is 3MPa, resulting in a second mixed gas and hydrogen-containing helium gas.

[0121] S3. In the presence of a targeted dehydrogenation membrane made of palladium-yttrium alloy, hydrogen-containing helium gas was subjected to targeted dehydrogenation at 450℃ and 3MPa, with a hydrogen permeation rate of 0.18mL / (cm²). 2 The pressure difference across the dehydrogenation membrane is 0.06 MPa, yielding crude helium and hydrogen, with the hydrogen product having a purity of 99.99%.

[0122] S4. The crude helium gas is purified by a second membrane separation, wherein the pressure P2 of the gas on the inlet side is 5MPa, resulting in helium gas and helium-lean gas. The helium-lean gas is returned to step S2 for the first membrane separation.

[0123] The raw material gas contains 20% helium, 17% methane, 60% nitrogen, 1% hydrogen, 0.5% carbon dioxide and 1.5% oxygen by volume.

[0124] The gas composition of each stage of the method is shown in Table 1:

[0125] Table 1

[0126] Gas composition % helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 20 60 17 1.5 1 0.5 0 The first mixture after drying 20.3 60.91 17.25 1.02 0.01 0.51 0 First-stage membrane separation 56.12 33.53 9.5 0.56 0.01 0.28 0 Secondary membrane separation 93.05 5.3 1.5 0.09 0.02 0.04 0 Targeted dehydrogenation of crude helium 93.064 5.301 1.502 0.089 0 0.044 0 Second membrane separation product 99.99 0.008 0.002 0 0 0 0

[0127] As can be clearly seen from the table above, this invention significantly reduces the concentration of impurity hydrogen through catalytic dehydrogenation, and effectively removes hydrogen that is difficult to separate from helium in the mixed gas by organically combining the two-stage first membrane separation process and targeted dehydrogenation technology. After the second membrane separation purification, the helium purity of the product can reach 99.99%, meeting the 4N standard.

[0128] For a more intuitive representation, the purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0129] Example 2

[0130] S1. In the presence of a Pb catalyst, oxygen is introduced at a volume ratio of feed gas to oxygen of 100:8, and a catalytic reaction is carried out at 106°C (based on the total amount of the feed gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:1.2) to obtain a first mixed gas.

[0131] S2. After drying the first mixed gas, a four-stage first membrane separation is performed in the presence of a polyimide hollow fiber membrane. During the first-stage membrane separation, the pressure P1-1 of the gas on the inlet side of the separation membrane is 10 MPa.

[0132] During stage 2 membrane separation, the pressure P1-2 of the gas on the inlet side of the separation membrane is 8 MPa;

[0133] During 3-stage membrane separation, the pressure P1-3 of the gas on the inlet side of the separation membrane is 8 MPa;

[0134] During stage 4 membrane separation, the pressure of the gas on the inlet side of the separation membrane, P1-4, is 8 MPa;

[0135] A second mixture of gas and hydrogen-containing helium gas were obtained;

[0136] S3, Same as in Example 1;

[0137] S4, Same as Example 1.

[0138] The gas composition of each stage of the method is shown in Table 2:

[0139] Table 2

[0140] Gas composition % helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 15.73 57.7 19.9 0 6.66 0.01 0 The first mixture after drying 16.04 58.83 20.29 4.78 0.03 0.01 0.02 First-stage membrane separation 41.36 41.05 14.16 3.33 0.08 0.01 0.01 Secondary membrane separation 67.88 22.42 7.73 1.82 0.14 0.004 0.005 Stage 3, first membrane separation 86.87 9.09 3.13 0.74 0.17 0.002 0.002 Stage IV, First Membrane Separation 96.996 1.977 0.682 0.161 0.184 0 0 Targeted dehydrogenation of crude helium 97.172 1.98 0.683 0.161 0.004 0 0 Second membrane separation product 99.992 0.005 0.001 0 0.002 0 0

[0141] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0142] Example 3

[0143] S1. In the presence of a Pb catalyst, oxygen is introduced at a volume ratio of feed gas to oxygen of 100:12, and a catalytic reaction is carried out at 106°C (based on the total volume of the feed gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:1.13) to obtain a first mixed gas.

[0144] S2. After drying the first mixed gas, a three-stage first membrane separation is performed in the presence of a polysulfone hollow fiber membrane. During the first-stage membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 3 MPa.

[0145] During stage 2 membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 3 MPa;

[0146] During 3-stage membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 4 MPa;

[0147] A second mixture of gas and hydrogen-containing helium gas were obtained;

[0148] S3, Same as in Example 1;

[0149] S4, Same as Example 1.

[0150] The gas composition of each stage of the method is shown in Table 3:

[0151] Gas composition % helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 19.7 53.7 15.9 0 10.65 0.05 0 The first mixture after drying 20.49 55.87 16.54 6.97 0.06 0.05 0.02 First-stage membrane separation 55.89 30.91 9.15 3.86 0.15 0.03 0.01 Secondary membrane separation 81.1 13.14 3.89 1.64 0.21 0.01 0.005 Stage 3, first membrane separation 94.613 3.625 1.073 0.452 0.232 0.003 0.001 Targeted dehydrogenation of crude helium 94.829 3.633 1.076 0.453 0.005 0.003 0 Second membrane separation product 99.994 0.003 0.001 0 0.002 0 0

[0152] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0153] Example 4

[0154] S1. In the presence of a Pt catalyst, oxygen is introduced at a volume ratio of feed gas to oxygen = 100:2, and a catalytic reaction is carried out at 100°C (based on the total volume of the feed gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:4) to obtain a first mixed gas.

[0155] S2. After drying the first mixed gas, a second-stage first membrane separation is performed in the presence of a flat sheet membrane module made of silica membrane material. During the first-stage first membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 0.2 MPa.

[0156] During the first membrane separation in stage 2, the pressure P1 of the gas on the inlet side of the separation membrane is 0.5 MPa;

[0157] A second mixture of gas and hydrogen-containing helium gas were obtained;

[0158] S3, Same as in Example 1;

[0159] S4, Same as Example 1.

[0160] The gas composition of each stage of the method is shown in Table 4:

[0161] Table 4

[0162] Operation / Composition% helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 17 35 35 6 2 5 0 The first mixture after drying 17.17 35.35 35.35 7.07 0.01 5.05 0 First-stage membrane separation 65.7 12.96 15.86 3.18 0.03 2.27 0 Secondary membrane separation 90.1 3.29 4.88 0.98 0.05 0.7 0 Targeted dehydrogenation of crude helium 90.147 3.297 4.881 0.977 0.001 0.697 0 Second membrane separation product 99.973 0.009 0.012 0.003 0.001 0.002 0

[0163] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0164] Example 5

[0165] S1. Consistent with Example 1, the catalytic temperature is 120°C;

[0166] S2. After drying the first mixed gas, a 5-stage first membrane separation is performed in the presence of a polyimide tubular membrane module. The pressure P1 of the gas on the inlet side during the first stage membrane separation is 3 MPa.

[0167] During stage 2 membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 2 MPa;

[0168] During 3-stage membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 2 MPa;

[0169] During stage 4 membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 2 MPa;

[0170] During 5-stage membrane separation, the pressure P1 of the gas on the inlet side of the separation membrane is 2 MPa;

[0171] A second mixture of gas and hydrogen-containing helium gas were obtained;

[0172] S3, Same as in Example 1;

[0173] S4, Same as Example 1.

[0174] The gas composition of each stage of the method is shown in Table 5:

[0175] Table 5

[0176]

[0177]

[0178] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0179] Example 6

[0180] S1, Same as in Example 1;

[0181] S2. After drying the first mixed gas, a first-stage membrane separation is performed in the presence of a polyimide hollow fiber membrane module. The pressure P1 of the gas on the inlet side during the first-stage membrane separation is 5 MPa.

[0182] S3, Same as in Example 1;

[0183] S4, Same as Example 1.

[0184] The gas composition of each stage of the method is shown in Table 6:

[0185] Table 6

[0186] Operation / Composition% helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 30 50 17 1.5 1 0.5 0 The first mixture after drying 30.454 50.757 17.257 1.018 0.005 0.508 0.002 First-stage membrane separation 92.093 5.762 1.959 0.116 0.012 0.058 0 Targeted dehydrogenation of crude helium 92.104 5.763 1.959 0.016 0.0003 0.058 0 Second membrane separation product 99.991 0.006 0.002 0.0002 0.0003 0.0001 0

[0187] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0188] Example 7

[0189] S1, Same as Example 1;

[0190] S2. In the presence of a targeted dehydrogenation membrane made of palladium-yttrium alloy, hydrogen-containing helium gas is subjected to targeted dehydrogenation at 450°C and 3MPa to obtain a second mixed gas and hydrogen-containing helium gas.

[0191] S3. After drying the first mixed gas, perform two-stage first membrane separation under the same conditions in the presence of a polysulfone hollow fiber membrane. During the first-stage first membrane separation, the pressure P1-1 of the gas on the inlet side of the separation membrane is 3MPa.

[0192] During the first membrane separation in stage 2, the pressure of the gas on the inlet side of the separation membrane, P1-2, is 3MPa, yielding crude helium and hydrogen.

[0193] S4. The crude helium gas is purified by a second membrane separation, wherein the pressure P2 of the gas on the inlet side is 5MPa, resulting in helium gas and helium-lean gas. The helium-lean gas is returned to step S2 for the first membrane separation.

[0194] The raw material gas contains 20% helium, 17% methane, 60% nitrogen, 1% hydrogen, 0.5% carbon dioxide and 1.5% oxygen by volume.

[0195] The gas composition of each stage of the method is shown in Table 7:

[0196] Table 7

[0197] Operation / Composition% helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 20 60 17 1.5 1 0.5 0 The first mixture after drying 20.3 60.91 17.25 1.02 0.01 0.51 0 Targeted dehydrogenation of crude helium 20.3 60.92 17.25 1.02 0 0.51 0 First-stage membrane separation 56.12 33.54 9.5 0.56 0 0.28 0 Secondary membrane separation 93.05 5.32 1.5 0.09 0 0.04 0 Second membrane separation product 99.99 0.008 0.002 0 0 0 0

[0198] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0199] Example 8

[0200] The method is consistent with that in Example 1, except that in step S3, hydrogen-containing helium gas is subjected to targeted dehydrogenation at 150°C and 1 MPa in the presence of a targeted dehydrogenation membrane made of palladium-yttrium alloy, with a hydrogen permeation rate of 0.05 mL / (cm²). 2 The pressure difference across the targeted dehydrogenation membrane is 0.01 MPa, yielding crude helium and hydrogen, with the hydrogen product having a purity of 99.976%.

[0201] The gas composition of each stage of the method is shown in Table 8:

[0202] Table 8

[0203] Gas / Composition % helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 20 60 17 1.5 1 0.5 0 The first mixture after drying 20.3 60.91 17.25 1.02 0.01 0.51 0 First-stage membrane separation 56.12 33.53 9.5 0.56 0.01 0.28 0 Secondary membrane separation 93.05 5.3 1.5 0.09 0.02 0.04 0 Targeted dehydrogenation of crude helium 93.052 5.301 1.501 0.09 0.014 0.042 0 Second membrane separation product 99.976 0.007 0.002 0 0.015 0 0

[0204] The purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0205] Comparative Example 1

[0206] The method is consistent with that of Example 1, except that the targeted dehydrogenation step is not included. The gas composition of each stage of the method is shown in Table 9.

[0207] Table 9

[0208] Operation / Composition% helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water The first mixture after drying 20 60 17 1.5 1 0.5 0 First membrane inlet gas 20.3 60.91 17.25 1.02 0.01 0.51 0 First-stage membrane separation 56.12 33.53 9.5 0.56 0.01 0.28 0 Secondary membrane separation 93.05 5.3 1.5 0.09 0.02 0.04 0 Second membrane separation product 99.967 0.008 0.003 0 0.022 0 0

[0209] Finally, the purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0210] Comparative Example 2

[0211] The method is consistent with that in Example 1, except that the condition for the second-stage first membrane separation is that the pressure P1 of the gas on the two inlet sides is 15 MPa, which exceeds the range that the membrane module can withstand, making it impossible to operate the purification process stably.

[0212] Comparative Example 3

[0213] The method is consistent with that in Example 1, except that in step S4, the crude helium gas is purified by a second membrane separation, wherein the pressure P2 of the gas on the inlet side is 0.2 MPa, and helium gas and lean helium gas are obtained. The lean helium gas is returned to step S2 for the first membrane separation.

[0214] The gas composition of each stage of the method is shown in Table 10:

[0215] Table 10

[0216] Operation / Composition% helium Nitrogen methane oxygen hydrogen <![CDATA[CO2]]> water raw material gas 20 60 17 1.5 1 0.5 0 The first mixture after drying 20.3 60.91 17.25 1.02 0.01 0.51 0 First-stage membrane separation 56.12 33.53 9.5 0.56 0.01 0.28 0 Secondary membrane separation 93.05 5.3 1.5 0.09 0.02 0.04 0 Targeted dehydrogenation of crude helium 93.064 5.301 1.502 0.089 0 0.044 0 Second membrane separation product 99.169 0.635 0.18 0.011 0 0.005 0

[0217] Finally, the purity and yield of helium and the purity of hydrogen are shown in Table 11.

[0218] Table 11

[0219] serial number Helium purity / % Helium yield / % Hydrogen purity / % Example 1 99.99 99.1 99.99 Example 2 99.992 98.8 99.99 Example 3 99.994 99 99.99 Example 4 99.973 97.5 99.99 Example 5 99.995 99.2 99.99 Example 6 99.991 98.1 99.99 Example 7 99.99 99.1 99.99 Example 8 99.976 99.0 99.99 Comparative Example 1 99.967 99.1 - Comparative Example 3 99.169 43.8 99.99

[0220] As can be seen from the results in Table 11, Examples 1-8 using the technical solution provided by the present invention have good effects. The purity of helium is high, and the hydrogen obtained is also high. However, the yield of Comparative Example 3 is significantly reduced due to the low inlet pressure.

[0221] Among them, embodiments 1-3 and 5-7 that satisfy the preferred embodiments of the present invention have significantly better effects, with helium purity not less than 99.99% and yield not less than 98%, while hydrogen purity not less than 99.99%.

[0222] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method of purifying helium gas, characterized by, The method comprises: S1. catalytically reacting raw gas and optionally oxygen in the presence of a catalyst to obtain first mixed gas; S2. performing first membrane separation on the first mixed gas to obtain second mixed gas and hydrogen-helium gas containing hydrogen; S3. performing targeted dehydrogenation on the hydrogen-helium gas containing hydrogen in the presence of a targeted dehydrogenation membrane to obtain crude helium gas and hydrogen; S4. performing second membrane separation on the crude helium gas to obtain helium gas and helium-lean gas, and returning the helium-lean gas to step S2 for first membrane separation; or a. catalytically reacting raw gas and optionally oxygen in the presence of a catalyst to obtain first mixed gas; b. performing targeted dehydrogenation on the hydrogen-helium gas containing hydrogen in the presence of a targeted dehydrogenation membrane to obtain second mixed gas and hydrogen-helium gas containing hydrogen; c. performing first membrane separation on the first mixed gas to obtain crude helium gas and hydrogen; d. performing second membrane separation on the crude helium gas to obtain helium gas and helium-lean gas, and returning the helium-lean gas to step S2 for first membrane separation; wherein the gas pressure P1 on the inlet side of the first membrane separation is 1-10 MPa; wherein the gas pressure P2 on the inlet side of the second membrane separation is 1-10 MPa; wherein the conditions of the catalytic reaction include a temperature of 60-120°C; The hydrogen permeation rate of the target dehydrogenation membrane is 0.1-0.3 mL / (cm 2 ·s). wherein the conditions of the targeted dehydrogenation include an operating temperature of 200-500°C and an operating pressure of 2-10 MPa.

2. The method of claim 1, wherein, In step S1, the amount of oxygen introduced is such that, based on the total amount of the raw gas and the oxygen, the molar ratio of hydrogen to oxygen is 1:1-4.

3. The method of claim 1, wherein, The catalyst is a noble metal catalyst.

4. The method of claim 3, wherein, The catalyst is selected from at least one of Pt, Pb, Rh, Ru and Au.

5. The method of any of claims 1-4, wherein, The conditions of the first membrane separation include P1> the gas pressure on the permeation side.

6. The method of claim 1, wherein, The first membrane separation is multistage membrane separation.

7. The method of claim 6, wherein, The first membrane separation is 1-5 stages of membrane separation.

8. The method of any one of claims 1-4, wherein, The first membrane separation is performed in the presence of a separation membrane selected from one of a flat membrane, a hollow fiber membrane and a tubular membrane.

9. The method of claim 8, wherein, The type of the separation membrane is selected from at least one of a homogeneous membrane, a heterogeneous membrane and a composite membrane.

10. The method of claim 9, wherein, The preparation method of the separation membrane is selected from at least one of thermal induced phase separation, solution induced phase separation, melt stretching, interfacial polymerization, coating polymerization and in-situ polymerization.

11. The method of any one of claims 1-4, wherein, The operating conditions of the second membrane separation include P2> the gas pressure on the permeation side.

12. A system for use in a method of purifying helium according to any one of claims 1 to 11, characterised in that, The system comprises, in sequence, a catalytic dehydrogenation unit, a membrane separation unit, a targeted dehydrogenation unit and a refining unit; The catalytic dehydrogenation unit is used for catalytically reacting raw gas to obtain first mixed gas; The membrane separation unit is used for performing first membrane separation on the first mixed gas from the catalytic dehydrogenation unit to obtain second mixed gas and hydrogen-helium gas containing hydrogen; The targeted dehydrogenation unit is used for performing targeted dehydrogenation on the hydrogen-helium gas containing hydrogen from the membrane separation unit to obtain crude helium gas and hydrogen; The targeted dehydrogenation unit is provided with a targeted dehydrogenation membrane; The refining unit is used for performing second membrane separation on the crude helium gas from the targeted dehydrogenation unit to obtain helium gas and helium-lean gas; The helium-lean gas is returned to the first membrane separation; or The catalytic dehydrogenation unit is used for catalytically reacting raw gas to obtain first mixed gas; The targeted dehydrogenation unit is used for targeted dehydrogenation of the hydrogen-containing helium gas from the membrane separation unit to obtain a second mixed gas and the hydrogen-containing helium gas; The membrane separation unit is used for first membrane separation of the first mixed gas from the catalytic dehydrogenation unit to obtain crude helium gas and hydrogen gas; The targeted dehydrogenation unit is provided with a targeted dehydrogenation membrane; The refining unit is used for refining the crude helium gas from the targeted dehydrogenation unit through second membrane separation to obtain helium gas and helium-lean gas; The helium-lean gas is returned to the first membrane separation.

13. Use of the method of any one of claims 1-11 and / or the system of claim 12 in at least one of the fields of energy, medicine and chemical industry.

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