CN111821818A

CN111821818A - Method and device for inorganic membrane multistage gas separation

Info

Publication number: CN111821818A
Application number: CN202010476743.1A
Authority: CN
Inventors: 顾学红; 谢继贤; 王学瑞; 张萍
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2019-06-27
Filing date: 2020-05-29
Publication date: 2020-10-27
Also published as: CN111874881B; CN111874881A

Abstract

The invention discloses an inorganic membrane multistage gas separation method, which comprises the following steps: s1, the raw material gas is pretreated in the pretreatment unit. And S2, the pretreated raw material gas enters a multi-stage membrane separation assembly for separation treatment, the permeation gas enters a lower-stage assembly, and the residual permeation gas continuously completes separation after refluxing. And S3, collecting and recycling gas products at the retentate side of the first-stage assembly and the permeate side of the last-stage assembly. The device comprises a pretreatment module, a single-stage membrane component, an air pump, a mass flow controller and a back pressure valve. Raw materials enter a multi-stage membrane module through a mass flow controller after being pretreated, a backpressure valve controls the pressure of the permeation side of a first-stage component, a plurality of components are connected in series through pipelines, each stage of permeation gas enters the next stage as raw material gas, the first-stage permeation gas is connected with the backpressure valve to control the top to be extracted, the rest of the permeation gas of each stage of component returns to the previous-stage component through an air pump to be mixed with feed gas, and a gas product at the permeation side of the last-stage component is collected at normal pressure.

Description

Method and device for inorganic membrane multistage gas separation

Technical Field

The invention relates to a method for multi-stage gas separation by an inorganic membrane, in particular to the separation and purification of binary or multi-component mixed gas with lower single-stage membrane separation selectivity.

Background

The gas product is used as an important basic raw material in modern industry, and has a wide application range. Besides common industrial gases in industry, special gases play an important role in industries such as electronic information, aerospace, petrochemical industry, medical environmental protection and the like. For example, ultra-pure nitrogen can be used as a protector of a super-large-scale integrated circuit, and neon isotopes can be used in the military industry such as missile guidance and the like. However, the scale of the special gas enterprises in China is small, the independent research and development results are few, the gas used for producing the submicron-scale integrated circuit cannot be produced in scale in China at present, the research and application of the isotope separation of the special gas belong to the starting stage, and the production dependence needs to be imported from abroad. The separation method of the mixed gas mainly comprises a low-temperature rectification method, a pressure swing adsorption method and a membrane separation method. The low-temperature rectification method relates to phase change separation, and has the advantages of high energy consumption, large device scale and high equipment cost; the pressure swing adsorption method has low recovery rate, needs continuous vacuumizing and compressing of gas, and also has the problems of high equipment cost, complex operation and the like. The field of special gas separation and purification also relates to methods such as a noble metal catalysis method, a thermal diffusion method, a molecular sieve purification technology and the like. However, the above methods all have the problems of high cost, high energy consumption, high equipment cost, complex operation and the like.

In the application of membrane separation of gas, a two-stage membrane separation and CO separation is mentioned in the patent with the patent number of CN201310329942.X₂The process of methane decarburization coupled with liquefaction needs to be coupled with low-temperature liquefaction, and the operation is more complicated; a device for separating gas by a three-section gas separation membrane unit is designed in a patent with the patent number of CN201510045066.7, an additional mixing container is added in the backflow process of the device, and the separation requirement of a system with a lower membrane separation coefficient is difficult to achieve, so that the limitation is large.

In addition, in a particular field of membrane separation applications,

disclosure of Invention

The invention aims to provide a method for separating and purifying inorganic membrane multistage gas, which solves the problems of high equipment investment, complex operation and high energy consumption of the traditional methods such as low-temperature rectification, pressure swing adsorption and the like. The series connection of the multistage membrane modules can effectively improve the separation purity of a mixed system with low membrane separation selectivity, realize the recovery of target gas, obviously increase the productivity and improve the economic benefit.

The multistage inorganic membrane gas separation method can meet the separation requirement only in the membrane separation process, is not coupled with other processes, and the residual gas of each stage can directly flow back to the upper stage; the separation of a gas system with lower single-stage membrane separation selectivity can be realized through multi-stage membrane separation, the separation efficiency is improved to a great extent, and the operation cost is reduced. The technology has great application potential in the fields of enrichment of oxygen, nitrogen and rare gas in air, preparation of high-purity electronic gas, separation and purification of isotope gas, nitrogen removal of natural gas in petrochemical industry, recovery and separation of hydrocarbon components and the like.

In an application field, the invention also realizes the on-line recycling technology of xenon in the closed-circuit medical xenon anesthesia process by adopting the DD3R molecular sieve membrane, and can recycle CO₂The selective separation of/Xe. Single component carbon dioxide permeability of 1.5X 10^-7mol·m^-2·s^-1·Pa^-1The selectivity for separation of carbon dioxide to xenon is 570. The permeation flux is higher than that of the traditional membrane material by one order of magnitude, and the DD3R molecular sieve has certain hydrophobicity due to the full silicon characteristic, so that the blockage of water vapor on the pore channels of the molecular sieve can be effectively weakened.

In a first aspect of the present invention, there is provided:

a method for inorganic membrane multistage gas separation comprising the steps of:

step 1, sending a gas mixture to be separated into gas separation equipment for separation;

the gas separation equipment is formed by connecting a plurality of membrane modules in series, and materials obtained from the permeation side of the previous stage are sent to the permeation side of the next stage for continuous separation; the obtained material on the retentate side of the next stage flows back to the retentate side of the upper stage for continuous separation;

and 2, obtaining a first gas component on the permeation side of the last stage, and obtaining a second gas component on the retentate side of the first stage.

In one embodiment, in step 1, the gas mixture to be separated is pretreated by a pretreatment unit on the gas mixture.

In one embodiment, the pretreatment comprises compression, drying, filtration, or heating.

In one embodiment, step 1, the gas product on the retentate side of the first stage is withdrawn under a back pressure valve.

In one embodiment, in step 1, the resulting material from the retentate side of the next stage is recirculated to the retentate side of the previous stage or stages.

In one embodiment, in step 1, the gas mixture to be separated is fed to the membrane module whose gas composition on the retentate side is closest to the gas composition of the gas mixture to be separated.

In one embodiment, in step 1, the feed pressure of the gas mixture to be separated is controlled in the range of 0.1 to 5 MPa.

In one embodiment, the reflux ratio needs to be set for the membrane module containing the refluxed retentate gas; wherein the reflux ratio is as follows: the amount of gas returned from the retentate side of the membrane module and the amount of gas to be separated entering the gas separation device.

In one embodiment, each stage of membrane modules has an operating temperature of 28K to 973K.

In one embodiment, the material used in the gas separation membrane installed in the membrane module may be one or more of inorganic membrane materials such as a molecular sieve membrane, a ceramic membrane, and a carbon membrane; the carrier of the gas separation membrane may be in the form of a tube or hollow fiber, etc.

In one embodiment, the gas mixture to be separated contains N₂、CO₂、H₂、O2、Kr、Xe、CH₄And one or more of He.

In one embodiment, the composition of the gas mixture to be separated is 5% CO₂,30％N₂And 65% Xe gas mixture, and further contains H₂O，H₂The partial pressure of O was 2.3 kPa; and the gas separation membrane used was a DD3R molecular sieve membrane.

In a second aspect of the present invention, there is provided:

an apparatus for inorganic membrane multistage gas separation comprising:

the pretreatment unit is used for pretreating a gas mixture to be separated;

the gas separation equipment is connected with the pretreatment unit and is used for separating gas components in the gas mixture to be separated;

the gas separation equipment comprises a plurality of membrane modules which are connected in series; the permeation side air outlet of the upper stage membrane component is connected with the residual side air inlet of the lower stage membrane component; the air outlet at the redundant side of the membrane module at the next stage is connected with the air inlet at the redundant side of the membrane module at the upper stage;

the gas outlet at the permeation side of the last stage of membrane module is connected with a first gas component receiving pipeline; and a second gas component receiving pipeline is connected with a gas outlet at the retentate side of the membrane module of the first stage.

In one embodiment, the membrane module comprises a shell and a gas separation membrane arranged in the shell; and the surplus side air inlet and the surplus side air outlet are connected to the shell, and the permeation side of the gas separation membrane is connected to the permeation side air outlet.

In one embodiment, the gas separation membrane is of the tubular or hollow fiber type.

In one embodiment, the material of the gas separation membrane is a molecular sieve membrane, a ceramic membrane, or a carbon membrane.

In one embodiment, the retentate side outlet port of the membrane module of the next stage is connected to the retentate side inlet port of the membrane module of the previous or previous stage.

In one embodiment, the retentate side air outlet of the membrane module of the next stage is connected with the membrane module of the upper stage by a micro air pump.

In one embodiment, the pretreatment unit is coupled to the gas separation device via a mass flow controller.

In one embodiment, the pretreatment unit is coupled to the membrane module of any stage.

In one embodiment, a back pressure valve is connected to the retentate side outlet of the membrane module of the first stage.

In a third aspect of the present invention, there is provided:

the device for inorganic membrane multistage gas separation is applied to multi-component gas separation.

Advantageous effects

The invention has simple operation, and can realize the separation and concentration of gas only by connecting the multistage membrane separation components in series. The device has low investment, can realize the separation of gas at normal temperature, is energy-saving and environment-friendly, and has remarkable economic benefit. For a mixed gas system with low single-stage membrane separation selectivity and low separation product purity, the multi-stage membrane separation can obviously improve the gas separation purity, and particularly can generate great economic benefit for the separation and concentration of some special gases.

Drawings

FIG. 1 is a schematic diagram of a separation process of a multi-stage series membrane separation device.

FIG. 2 is a schematic diagram of several exemplary retentate gas (except for the first stage) reflux modes.

FIG. 3 shows the Xe molar composition vs. CO₂Influence of the/Xe mixture separation Performance (feed pressure: 3 bar).

FIG. 4 shows the separation performance of DD3R molecular sieve membrane.

FIG. 5 shows a DD3R molecular sieve membrane vs. CO₂And Xe separation performance.

Wherein, 1, a pretreatment unit; 2. a mass flow controller; 3. a membrane module; 4. a housing; 5. a gas separation membrane; 6. a redundant side air inlet; 7. a surplus side air outlet; 8. sealing the end; 9. a permeate side gas outlet; 10. a pipeline; 11. a trace air pump, 12 and a back pressure valve.

Detailed Description

Fig. 1 shows that the raw material gas is pretreated by a pretreatment unit 1, so that parameters such as moisture content, pressure and temperature in the raw material gas meet requirements. The pretreatment unit 1 used in the present invention is not particularly limited, and may include a compression device, a drying device, a filtering device or a heating device, and the raw material is pretreated before entering the series membrane separation module to meet the corresponding gas state requirement. The treated feed gas enters the multi-stage membrane separation module at the appropriate feed position via mass flow controller 2.

In the present invention, when the membrane modules are connected in series, the module located at the most upstream is the 1 st stage, and the (most downstream) stage where the retentate gas is discharged as a final product is the nth stage.

The single membrane module used in the present invention is shown in fig. 1, wherein the membrane module 3 comprises a shell 4 and an internal gas separation membrane 5, the shell 4 is made of stainless steel or nylon, the shell 4 and the gas separation membrane 5 divide the space in the module into a permeation side and a retentate side, the tubular gas separation membrane 5 is taken as an example in the figure and is in a tubular configuration, and the separation layer is selected to be located outside the tubular membrane. An air inlet 6 and an air outlet 7 are arranged on the shell, two ends of the shell adopt seal heads 8 with threads, one end of the shell is provided with an air outlet 9 at the permeation side, and the other end of the shell is a dead end. The single-stage membrane components 3 are connected in series by a pipeline 10, and the permeation side gas outlet 9 of the previous stage is connected with the gas inlet 6 of the next stage shell to complete the series operation of the device; and the residual gas outlet 7 of the lower-stage component is connected with the shell gas inlet 6 of the upper-stage component to complete the reflux operation.

When the structure is adopted, a main improvement point is that when the gas to be separated fed contains A, B components, when a single-stage membrane module is adopted for separation, a component B is supposed to enter a permeation side, and the residual gas (supposed to be A) cannot reach enough purity, so that the residual gas cannot be effectively reused, and when the residual gas is refluxed to a higher stage for continuous separation, the concentrated gas containing A can be further concentrated for a second time, and after the gas B is continuously fed to a series module of a next stage, the material mainly containing the gas B is further separated, so that the first stage obtains purer A, and the last stage obtains purer B.

FIG. 1 shows that the raw material gas is separated in a multi-stage series membrane module, the permeation gas of each stage of module enters the next stage of module for continuous separation, and the residual gas returns to the previous stage through an air pump 11 to be mixed with the feed gas.

Fig. 1 shows that the permeate product separated at the permeate measuring port 4 of the last stage module is collected. The gas outlet 7 at the retentate side of the first-stage component is connected with a backpressure valve 12 to control the gas outlet amount of retentate gas, and a retentate product is obtained by the withdrawal of the backpressure valve 12.

The return of the residual gas includes but is not limited to the return mode of returning to the previous stage module, and the return of the residual gas to other membrane module air inlets before the current stage module can be adjusted according to the requirement to be mixed with the feed gas. The return flows of the gas on the retentate side may be all sequentially returned to the previous stage, may be returned to several stages, or may be returned to the same stage as the previous stage by a plurality of membrane modules, as shown in fig. 2.

In addition, except the first-stage residual gas detection port, when impurities are contained in a system to be separated and the impurities are enriched to high concentration after separation of a certain number of stages, a branch is added at the residual gas detection port of a proper number of stages for extraction, so that the influence of high-concentration gas on the membrane separation of a target system is reduced.

In the feeding process of the raw materials of the first-stage membrane assembly, the pressure range is controlled to be 0.1-5 MPa.

The operating temperature range of the gas separation process of each stage of the components is 28K-973K.

In the return process of the residual gas of each stage of the components, the range of the gas return ratio (the return ratio refers to the ratio of the amount of the gas returned from the residual side of the membrane component of the stage to the amount of the gas to be separated entering the gas separation equipment) of the micro gas pump is controlled to be less than 10. For example: a series of 10 membrane modules are included in the series, with the mixed gas feed location at the 5 th membrane module, then for the 4 th membrane module, which has both gas from the 5 th permeate side as reflux and gas from the 3 rd permeate side, then the reflux ratio is: the 4 th stage retentate side reflux gas amount (3 rd stage permeate side gas amount + 5 th stage retentate side reflux amount-4 th stage gas permeation amount)/the amount of gas to be separated entering the gas separation apparatus.

The pore diameter of the inorganic membrane material adopted in the separation device is within the range of 2-200 nm.

The inorganic membrane used in the membrane separation device can be one or more of a ceramic membrane, a molecular sieve membrane and a carbon membrane. The support may be in the form of a tube or hollow fibre or the like.

Example 1

80% N₂And 20% of O₂Introducing the mixed gas into a pretreatment device, removing water and other solid particles in the mixed gas, enabling the temperature of the treated gas to reach 25 ℃, and pressurizing to 1.5 MPa. The pretreated raw gas enters the separation device through a first-stage air inlet at a certain feeding quantity through a mass flow controller, and a first-stage assembly seepage side air outlet is connected with a back pressure valve to control the seepage side pressure to be stabilized at 3.5-4 bar (gauge pressure). The residual gas of each stage of assembly returns to the previous stage of assembly through the air pump, and the reflux ratio is 0.8. The membrane material in each stage of membrane separation assembly is TiO₂The alumina hollow fiber membrane is coated, the aperture of the membrane is 100nm, and the membrane has high mechanical strength and excellent oxidation resistance.

Under the condition, the last stage of permeation gas is extracted at normal pressure, and is subjected to 45-stage membrane separation, and the last stage of permeation gas is obtainedN in grade permeation gas₂Concentration of (2)>99 percent. Permeate gas exiting the first stage assembly through the backpressure valve may be vented directly to the atmosphere.

Example 2

A mixed gas consisting of 80% Kr and 20% Xe was introduced into the pretreatment unit, pressurized to 3MPa and kept at a gas temperature of about 25 ℃. And introducing the pretreated mixed gas into a 10 th-stage membrane component gas inlet of the series device, controlling the feeding amount through a mass flow controller, and controlling the gas outlet amount of the first-stage residual gas by regulating and controlling a back pressure valve. The residual gas of each stage of assembly returns to the previous stage of assembly through a micro gas pump, and the reflux ratio is 1. The inorganic ceramic membrane is used as a membrane separation material, the membrane aperture is 50nm, and the inorganic ceramic membrane has high mechanical strength and excellent oxidation resistance. And the residual gas discharged by the first stage assembly through the backpressure valve is recycled, wherein the concentration of Xe is about 35%. The last stage of permeate gas is taken as a raw material and is extracted under normal pressure, and the separation stages required for reaching different theoretical purities are as follows:

example 3

Will N₂Content (wt.)<10% of natural gas (main component CH)₄>90%) of the mixed gas is introduced into a pretreatment unit, the water content and other solid particles in the mixed gas are removed, the mixed gas is pressurized to 0.7MPa, and the temperature of the mixed raw material gas is controlled to be about 25 ℃. And introducing the pretreated mixed gas into a 10 th-stage membrane component air inlet of the series device, controlling the feeding amount through a mass flow controller, and controlling the air output of the first-stage residual gas by a first-stage regulation backpressure valve so that the pressure of a first-stage residual gas side is stabilized at 3.5-4 bar (gauge pressure). The residual gas of each stage of assembly returns to the previous stage of assembly through the air pump, and the reflux ratio is 1.5. An electrodeless ceramic membrane is used as a separation material, and the membrane aperture is 100-150 nm.

Under these conditions, after 20 stages of separation, the last permeate is taken at atmospheric pressure, where CH is present₄Concentration of (2)>99 percent of the permeation gas is collected as a product, and the first-stage assembly residual gas except the reflux is discharged through a backpressure valve and then is recoveredAnd (4) utilizing.

Example 4

Will have a composition of 50% He and 50% N₂The mixed gas is introduced into a treatment unit, the mixed gas is pressurized to 1MPa, and the temperature is controlled at room temperature. And (3) feeding the pretreated raw material mixer into a 6-stage series membrane module through a 4-stage component gas inlet for separation, and controlling the feeding amount to be 1.5L/h through a mass flow controller. And controlling a back pressure valve to regulate and control the pressure of the first-stage residual seepage side to be 3-3.5 bar stably. The residual gas of the first-stage component is directly recovered through a backpressure valve, the reflux ratio of other components is kept at 0.66, the reflux quantity of each-stage component is ensured to be 1L/h, the reflux direction returns to the feeding of the previous-stage component, and the permeation quantity of each stage and the final bottom extraction quantity are maintained at 0.5L/h. The separation membrane material adopts a hollow fiber molecular sieve membrane, the aperture of the membrane is 2nm, and the membrane has excellent mechanical stability. The last stage of the permeate gas is extracted at normal pressure and collected as a product. Under these conditions, the parameters of each stage are obtained according to the balance as shown in the following table:

example 5

Will have a composition of 90% H₂And 10% CO₂The mixed gas is introduced into a pretreatment unit, pressurized to 0.5MPa and kept at a gas temperature of about 25 ℃. And introducing the pretreated mixed gas into a 5 th-stage membrane component air inlet of the series device, controlling the feeding amount through a mass flow controller, and regulating and controlling the outlet amount of the first-stage residual seepage gas by a back pressure valve so that the pressure of the first-stage residual seepage side is stabilized at 2-2.4 bar (gauge pressure). The residual gas of each stage of assembly returns to the previous stage of assembly through the air pump, and the reflux ratio is 0.5. A hollow fiber molecular sieve membrane is used as a separation membrane material.

Under the condition, after 9 stages of component separation, the concentration of hydrogen in the permeation gas of the last stage>99.9%, the permeating gas is taken out as raw material under normal pressure, the permeating residual gas discharged from the first stage assembly through a back pressure valve is recycled, wherein CO is contained₂Is about 30%, in this example, is the feed to the 5 th stage membrane module, after separation in this stage, the gas on the retentate side of stage 5The body contains 16.3% of CO₂And 84.7% of H₂As can be seen by comparison, the CO is finally realized by refluxing the gas on the retentate side of the stage to the previous stage₂Further concentration of the gas.

Example 6

In the embodiment, the DD3R molecular sieve membrane is used for an online recycling technology of xenon in the closed-circuit medical xenon anesthesia process. Single component carbon dioxide permeability of 1.5X 10^-7mol·m^-2·s^-1·Pa^-1The selectivity for separation of carbon dioxide to xenon is 570. The permeation flux is an order of magnitude higher than that of conventional membrane materials. The membrane separation performance is mainly formed by CO₂And the difference in the diffusion coefficient of Xe molecules in DD3R molecular sieve. However, CO₂The mass transfer rate of the membrane is remarkably reduced due to the existence of Xe, which is the same as that of the prior eight-membered ring molecular sieve membrane in CO₂/N₂And CO₂/CH₄The separation results for the binary components vary widely. The molecular dynamics simulation result shows that Xe molecules are adsorbed on the surface of the molecular sieve membrane to form CO₂Surface resistance to adsorption and diffusion. Under the relevant conditions of medical xenon anesthesia, namely the carbon dioxide content is lower than 5 percent and the water vapor exists, CO₂Permeability and CO₂The selectivity of/Xe separation was 2.0X 10, respectively^-8mol·m^-2·s^-1·Pa^-1And 67. CO due to the all-silicon character of DD3R molecular sieve film₂The permeability of the membrane is slightly influenced by water vapor, which is different from that the aluminum-containing molecular sieve membrane pore channel is easily blocked by water adsorption. High CO content₂Flux and high CO₂the/Xe selectivity and the long-term stability ensure the good prospect of the hollow fiber DD3R molecular sieve membrane on-line recycling of xenon in medical anesthesia. The DD3R molecular sieve membrane used in this example can be prepared by the prior art, for example, CN110745839A "a process for activating a defect-free DD3R molecular sieve membrane".

First, CO is carried out₂Separation test of/Xe Mixed gas, FIG. 3 shows the Xe molar composition versus CO₂Influence of the/Xe gas mixture separation Performance (feed pressure: 3bar), CO₂Permeability decreases with Xe groupThe increase in composition is more pronounced (region c of fig. 2). Finally, when CO is present₂When the content is reduced to 5%, CO₂Permeability of 0.24X 10^-7mol·m^-2·s^-1·Pa^-1(ii) a However, CO₂The separation selectivity of/Xe was always around 43, showing CO₂Good separation selectivity at low concentration.

CO of hollow fiber DD3R molecular sieve membrane reported in this application₂The permeability of the single component is 1.5X 10^-7mol·m^-2·s^-1·Pa^-1And is an order of magnitude higher than the results reported in the previous literature (region a of fig. 4). DD3R molecular sieve membrane for CO at different temperatures₂Single component, CO₂/H₂Binary component of O and CO₂/H₂The O/Xe ternary component separation performance is shown in region b of FIG. 4; region c of FIG. 4 is the composition at 3bara of DD3R molecular sieve membrane of 0.76% H₂O、4.96％CO₂、29.77％N₂And 64.51% Xe. Water vapor is often present in the anesthetic exhaled breath. Due to the presence of water vapor, CO₂The single-component permeability is reduced by 37-45% (region b of FIG. 4); however, under the same conditions, the gas permeability of the aluminum-containing 8-membered ring molecular sieve membrane is reduced more remarkably, and the DD3R molecular sieve membrane has better hydrophobic property, so that CO brought by water vapor adsorption can be effectively weakened₂The permeability is reduced. Using aprotic template agent and ion-free synthesis solution for preparing more hydrophobic DD3R molecular sieve film for CO in wet gas environment₂Separation of/Xe. Further study on CO by steam₂The effect of permeability and selectivity is shown in region b of fig. 3 and region a of fig. 5. In a water vapor environment, the separation selectivity of the membrane is higher than that of the dry gas. Si-OH at the grain boundary of the molecular sieve film layer can strongly adsorb water molecules, thereby blocking the diffusion of gas molecules at the pore canals. Therefore, in a moisture environment, the permeability of Xe is lower than in dry gas. The permeation of water vapor gradually decreases with increasing temperature, e.g., by 55% at 100 ℃; the temperature is reduced by 52 percent at 125 ℃; the reduction was 42% at 150 ℃. However, in both wet and dry gases, CO₂The permeability of the molecule is mainly contributed by the DD3R molecular sieve.

During the anesthesia process, the impurities of the expired anesthetic gas are except CO₂In addition, human tissue and organs release nitrogen during the initial phase of anesthesia. It was used for 5% CO₂,30％N₂And recovering xenon from the 65% Xe gas mixture. After introduction of 2.3kP steam, CO₂And N₂All slightly decreased (fig. 3) finally, the permeability of carbon dioxide stabilized at 2.0 × 10^-8mol·m^-2·s^-1·Pa^-1， CO₂the/Xe selectivity is 67 +/-12; n is a radical of₂Permeability of 2.4X 10^-9mol·m^-2·s^-1·Pa^-1，N₂the/Xe selectivity was 8. + -.2.

In the above, the separation experiment for recovering xenon by using the one-stage DD3R separation membrane was performed, and then, deep recovery was performed by using multi-stage separation. When the 3-stage series separation process is adopted, according to the same operation conditions, the recovered xenon containing 99.19 percent of Xe and 99.23 percent of Xe is obtained in the 2 nd stage and the 3 rd stage in sequence, which shows that the xenon with higher purity can be obtained by multi-stage series separation.

Claims

1. A method for inorganic membrane multistage gas separation, comprising the steps of:

2. The inorganic membrane multistage gas separation method of claim 1, wherein in step 1, the gas mixture to be separated is pretreated by a pretreatment unit for the mixed gas;

3. The inorganic membrane multi-stage gas separation process of claim 1 wherein in step 1, the gas product on the retentate side of the first stage is withdrawn under a back pressure valve control;

in one embodiment, in step 1, the resulting material from the retentate side of the next stage is refluxed to the retentate side of the previous stage or stages;

in one embodiment, in step 1, the gas mixture to be separated is fed to the membrane module whose gas composition on the retentate side is closest to the gas composition of the gas mixture to be separated;

4. The method for multistage inorganic membrane gas separation according to claim 1, wherein a reflux ratio is required to be set for the membrane module containing the refluxed retentate gas; wherein the reflux ratio is as follows: the return gas quantity of the retentate side of the membrane module and the gas quantity to be separated entering the gas separation equipment;

in one embodiment, the working temperature of each stage of membrane module is 28K-973K;

5. The method of inorganic membrane multi-stage gas separation of claim 1, wherein in one embodiment, the gas mixture to be separated contains N₂、CO₂、H₂、O2、Kr、Xe、CH₄And one or more of He;

in one embodiment, the composition of the gas mixture to be separated is 5% CO₂, 30% N₂And 65% Xe gas mixture, and further contains H₂O， H₂The partial pressure of O was 2.3 kPa; and the gas separation membrane used was a DD3R molecular sieve membrane.

6. An apparatus for inorganic membrane multistage gas separation, comprising:

a pre-treatment unit (1) for pre-treating a gas mixture to be separated;

the gas separation equipment is connected with the pretreatment unit (1) and is used for separating gas components in a gas mixture to be separated;

the gas separation equipment comprises a plurality of membrane modules (3), and the membrane modules (3) are connected in series; the permeation side air outlet (9) of the upper stage membrane component (3) is connected with the residual side air inlet (6) of the lower stage membrane component (3); a surplus side air outlet (7) of the membrane module (3) at the next stage is connected with a surplus side air inlet (6) of the membrane module (3) at the upper stage;

an air outlet (9) at the permeation side of the membrane component (3) at the last stage is connected with a first gas component receiving pipeline; a second gas component receiving pipeline is connected with a gas outlet (7) at the retentate side of the membrane component (3) of the first stage.

7. The inorganic membrane multistage gas separation device according to claim 6, wherein in one embodiment, the membrane module (3) comprises a shell (4) and a gas separation membrane (5) installed in the shell (4); the residual side gas inlet (6) and the residual side gas outlet (7) are connected to the shell (4), and the permeation side of the gas separation membrane (5) is connected to the permeation side gas outlet (9);

in one embodiment, the gas separation membrane (5) is of tubular or hollow fiber type;

in one embodiment, the material of the gas separation membrane (5) is a molecular sieve membrane, a ceramic membrane or a carbon membrane.

8. The inorganic membrane multistage gas separation apparatus according to claim 6, wherein in one embodiment, the retentate side gas outlet (7) of the membrane module (3) of the next stage is connected to the retentate side gas inlet (6) of the membrane module (3) of the previous stage or stages;

in one embodiment, the retentate side air outlet (7) of the membrane module (3) at the next stage is connected with the membrane module (3) at the upper stage by a micro air pump (11).

9. The apparatus for inorganic membrane multistage gas separation according to claim 6, characterized in that in one embodiment the pretreatment unit (1) is connected to the gas separation device by means of a mass flow controller (2);

in one embodiment, the pretreatment unit (1) is connected to the membrane module (3) of any stage;

in one embodiment, a back pressure valve (12) is connected to the retentate side gas outlet (7) of the first stage membrane module (3).

10. Use of the apparatus for inorganic membrane multistage gas separation of claim 6 for multi-component gas separation.