Separation membrane system

Abstract

Provided is a separation membrane system that comprises a separation membrane that preferentially permeates and separates a combustible gas or a non-combustible gas from a mixed gas of the combustible gas and the non-combustible gas, and that makes it possible to effectively utilize or burn a gas in which the concentration of the non-combustible gas has been increased (concentrated). A separation membrane system according to an embodiment of the present invention is a separation membrane system for separating a mixed gas of a combustible gas and a non-combustible gas on the basis of permeability, the separation membrane system comprising a separation membrane that preferentially permeates the combustible gas or the non-combustible gas and that separates the mixed gas from the combustible gas on the basis of permeability. The mixed gas is separated into a combustible gas concentrated gas and a non-combustible gas concentrated gas, and the non-combustible gas concentrated gas can be combusted.

Description

Technical Field

[0001] The present invention relates to a separation membrane system. Background Art

[0002] Conventionally, various methods for separating useful gases from mixed gases have been studied. As such a method, for example, a method using a separation membrane that allows a specific gas to selectively permeate is known. In a separation membrane system that allows a given gas to permeate in order to concentrate a combustible gas and a non-combustible gas to high concentrations in a mixed gas of a combustible gas and a non-combustible gas, the concentrated non-combustible gas is mostly not used and is discarded, becoming uneconomical.

[0003] Prior Art Documents Patent Documents Patent Document 1: International Publication No. 2011 / 105511 Summary of the Invention

[0004] Problems to be Solved by the Invention The main object of the present invention is to provide a separation membrane system including a separation membrane that preferentially allows a combustible gas or a non-combustible gas to permeate from a mixed gas of a combustible gas and a non-combustible gas, and the gas after high-concentration (concentration) of the non-combustible gas can be effectively utilized through the separation membrane.

[0005] Solutions to the Problems [1] A separation membrane system according to an embodiment of the present invention is a separation membrane system that separates a mixed gas of a combustible gas and a non-combustible gas based on permeability, wherein the separation membrane system includes a separation membrane that preferentially allows the combustible gas or the non-combustible gas to permeate, separates the mixed gas into a combustible gas concentrated gas and a non-combustible gas concentrated gas, and the non-combustible gas concentrated gas can be burned.

[0006] [2] In the separation membrane system of [1] above, it may be that a removal mechanism for impurity components is provided upstream of the separation membrane.

[0007] [3] In the separation membrane system of [1] above, it may be that the non-combustible gas concentrated gas contains nitrogen.

[0008] [4] In the separation membrane system of [2] above, it may be that the non-combustible gas concentrated gas contains nitrogen.

[0009] [5] In the separation membrane system according to any one of [1] to [4] above, it may be that the main component of the non-combustible gas in the non-combustible gas concentrated gas is nitrogen.

[0010] [6]In the separation membrane system according to any one of [1] to [5] above, it is also possible to use the non-combustible gas enriched gas for temperature adjustment of the separation membrane.

[0011] [7]In the separation membrane system according to any one of [1] to [6] above, it is also possible to use the non-combustible gas enriched gas for heating of other separation membranes.

[0012] [8]In the separation membrane system according to any one of [1] to [7] above, it is also possible to use a part of the mixed gas for temperature adjustment of the separation membrane.

[0013] [9]In the separation membrane system according to any one of [1] to [8] above, it is also possible to use the combustible gas enriched gas for temperature adjustment of the separation membrane.

[0014] Advantages of the Invention According to an embodiment of the present invention, it is possible to provide a separation membrane system including a separation membrane that preferentially allows a combustible gas or a non-combustible gas to permeate through a mixed gas of a combustible gas and a non-combustible gas, and through which the gas with a high concentration (enriched) of the non-combustible gas can be effectively utilized. Brief Description of the Drawings

[0015] Figure 1 It is an explanatory diagram showing an outline of a separation membrane system according to an embodiment of the present invention.

[0016] Figure 2 It is an explanatory diagram showing an outline of a separation membrane system according to an embodiment of the present invention.

[0017] Figure 3 It is a schematic explanatory diagram showing the structure of a separation membrane composite in an embodiment of the present invention.

[0018] Figure 4 It is a schematic cross-sectional view showing the structure of a separation membrane composite in an embodiment of the present invention. Detailed Embodiments

[0019] A. Outline of the Separation Membrane System Figure 1 It is an explanatory diagram showing an outline of a separation membrane system according to an embodiment of the present invention. The separation membrane system 100 is configured to separate a mixed gas of a combustible gas and a non-combustible gas based on permeability. The separation membrane system 100 includes a separation membrane. This separation membrane preferentially allows a combustible gas or the non-combustible gas to permeate, and separates the mixed gas into a combustible gas enriched gas and a non-combustible gas enriched gas. In one embodiment, the separation membrane can form a separation membrane composite 10.

[0020] In one embodiment, as the above-mentioned separation membrane, a separation membrane that preferentially permeates non-flammable gas is used ( Figure 1 as in (a)). In this embodiment, the concentration of non-flammable gas in the gas that has permeated the above-mentioned separation membrane (hereinafter also referred to as the permeated gas) is higher than the concentration of non-flammable gas in the mixed gas (hereinafter also referred to as the gas to be treated) before contacting the separation membrane. On the other hand, in the separation membrane system, the concentration of non-flammable gas in the gas that has not permeated the above-mentioned separation membrane (hereinafter also referred to as the non-permeated gas) is lower than the concentration of non-flammable gas in the gas to be treated. In addition, in this embodiment, in the separation membrane system, the concentration of flammable gas in the above-mentioned non-permeated gas is higher than the concentration of flammable gas in the gas to be treated. It should be noted that the non-permeated gas can be flammable. In this specification, a gas with a higher concentration of non-flammable gas than the gas to be treated (a mixed gas of flammable gas and non-flammable gas before contacting the separation membrane) is referred to as a "non-flammable gas enriched gas". In this embodiment, the permeated gas is a "non-flammable gas enriched gas". In addition, a gas with a higher concentration of flammable gas is referred to as a "flammable gas enriched gas". In this embodiment, the non-permeated gas is a "flammable gas enriched gas".

[0021] In another embodiment, as the above-mentioned separation membrane, a separation membrane that preferentially permeates flammable gas is used ( Figure 1 as in (b)). In this embodiment, the concentration of non-flammable gas in the non-permeated gas is higher than the concentration of non-flammable gas in the gas to be treated. On the other hand, the concentration of non-flammable gas in the permeated gas is lower than the concentration of non-flammable gas in the gas to be treated. In addition, in this embodiment, the concentration of flammable gas in the above-mentioned permeated gas is higher than the concentration of flammable gas in the gas to be treated. It should be noted that the permeated gas can be flammable. In this embodiment, the non-permeated gas is a "non-flammable gas enriched gas". In addition, the permeated gas is a "flammable gas enriched gas".

[0022] In one embodiment, the above-mentioned separation membrane system has a removal mechanism for impurity components as a pretreatment device upstream of the separation membrane. The impurity components can be solid components, liquid components, or gas components. When a heating device is provided as described later, the removal mechanism can be provided upstream or downstream of the heating device.

[0023] The object gas to be processed as described above is, for example, a mixed gas containing hydrogen, helium, nitrogen, oxygen, carbon monoxide, carbon dioxide, nitrogen oxides, ammonia, sulfur oxides, hydrogen sulfide, sulfur hexafluoride, mercury, arsine, hydrogen cyanide, carbonyl sulfide, hydrocarbons having 1 to 8 carbon atoms, organic acids, alcohols, thiols, esters, ethers, ketones, aldehydes, etc. In this specification, a flammable gas means a gas that is flammable in the presence of oxygen. Examples of flammable gases include hydrocarbon gases (methane, ethane, propane, butane, ethylene, etc.), hydrogen, carbon monoxide, etc. In addition, examples of non-flammable gases include nitrogen, carbon dioxide, etc. In one embodiment, nitrogen is used as the non-flammable gas. In addition, a non-flammable gas containing nitrogen as the main component can also be used. In this specification, the "main component" means the component with the highest concentration among the non-flammable gas components. In the above mixed gas, the mixing ratio of the flammable gas and the non-flammable gas can be any suitable mixing ratio. In one embodiment, the above separation membrane system is used as a purification unit for natural gas (for example, a mixed gas of nitrogen and hydrocarbons).

[0024] In the above separation membrane system, the non-flammable gas enriched gas is a gas that can burn. In an embodiment of the present invention, by being configured to generate a non-flammable gas enriched gas while making the gas combustible, the non-flammable gas enriched gas can be effectively utilized. Representatively, the non-flammable gas enriched gas as waste gas can be combusted, and as a result, the disposal cost of the non-flammable gas enriched gas can be reduced. In addition, the non-flammable gas enriched gas can also be used for temperature adjustment of the separation membrane (details will be described later). In one embodiment, based on the structure of the separation membrane itself, the non-flammable gas enriched gas is a gas that can burn, that is, without introducing a flammable gas different from the non-flammable gas enriched gas, the non-flammable gas enriched gas becomes a gas that can burn. It should be noted that a gas can burn means that (without additional introduction of a flammable gas) it can be within the combustion range in the presence of an oxidizing gas, at atmospheric pressure, and at room temperature. Preferably, it means that it can be within the combustion range at atmospheric pressure and room temperature by mixing with air.

[0025] The above non-flammable gas enriched gas can be stored, etc. and used outside the separation membrane system, or can be used within the above separation membrane system. In one embodiment, the above separation membrane system includes combusting the above non-flammable gas enriched gas.

[0026] In one embodiment, the above non-flammable gas enriched gas is used for temperature adjustment of the above separation membrane ( Figure 1(c)). The temperature-regulated separation membrane of the present embodiment can be a separation membrane for generating a non-combustible gas-enriched gas. Since the separation accuracy of the separation membrane varies with temperature, by appropriately adjusting the temperature, the composition of the non-combustible gas-enriched gas can be controlled within the combustion range. In one embodiment, the temperature of the separation membrane is adjusted by heating the gas to be treated with the heated non-combustible gas-enriched gas. Preferably, the gas to be treated is heated using the heat obtained by burning the non-combustible gas-enriched gas in the presence of a combustion-supporting gas. All or a part of the generated non-combustible gas-enriched gas can be used for the above temperature adjustment. A heating device (such as an electric heater) different from it can also be provided in the front stage of the separation membrane. In this case, by using the heat obtained by burning the non-combustible gas-enriched gas, the load of the above heating device can be reduced.

[0027] In one embodiment, the temperature of the above separation membrane is adjusted using the gas to be treated (a mixed gas of a combustible gas and a non-combustible gas before contacting the separation membrane) and / or a combustible gas-enriched gas. Representatively, as Figure 2 shown, the gas to be treated is heated using the gas obtained by heating a part of the gas to be treated and / or the combustible gas-enriched gas, thereby adjusting the temperature of the separation membrane. Preferably, the gas to be treated is heated using the heat obtained by burning a part of the gas to be treated and / or the combustible gas-enriched gas in the presence of a combustion-supporting gas. It should be noted that Figure 2 (a) shows an embodiment in which a part of the gas to be treated is burned to heat the gas to be treated. In addition, Figure 2 (b) shows an embodiment in which a part of the combustible gas-enriched gas as a non-permeating gas is burned to heat the gas to be treated. In addition, Figure 2 (c) shows an embodiment in which a part of the combustible gas-enriched gas as a permeating gas is burned to heat the gas to be treated.

[0028] In addition, as Figure 2 (a') to (c') shown, the temperature of the separation membrane can also be adjusted using the gas obtained by mixing the non-combustible gas-enriched gas with the gas to be treated and / or the combustible gas-enriched gas.

[0029] In one embodiment, the above non-combustible gas-enriched gas is used for heating other separation membranes ( Figure 1(d)). In this embodiment, in addition to adjusting the temperature of the separation membrane when the separation performance is found, when the device equipped with the separation membrane is started (during heating), the non-flammable gas concentrated gas can also be used. Other separation membranes can be the separation membranes within the above-mentioned separation membrane system or the separation membranes outside the separation membrane system. For example, Japanese Unexamined Patent Application Publication No. 2009-039654 discloses a system for preventing condensation on the membrane surface by heating during the start-up of the separation membrane, and Japanese Patent No. 6500499 discloses a system for drying the separation membrane by heating. All of the generated non-flammable gas concentrated gas can be used for heating other separation membranes, or a part of it can be used for heating other separation membranes.

[0030] In one embodiment, the above-mentioned separation membrane system includes burning the non-flammable gas concentrated gas that has been used in the heating of the separation membrane (or other separation membranes) as described above. The heating of the separation membrane can be carried out by supplying the heated non-flammable gas concentrated gas to the separation membrane, or by the heat obtained from burning a part of the non-flammable gas concentrated gas in the presence of a combustion-supporting gas. According to such an embodiment, the non-flammable concentrated gas can be utilized more effectively.

[0031] In one embodiment, the above-mentioned non-flammable gas concentrated gas contains nitrogen. In addition, the non-flammable gas contained in the above-mentioned non-flammable gas concentrated gas may also contain nitrogen as the main component. In this specification, the "main component" refers to the component with the highest concentration among the components in the non-flammable gas.

[0032] It should be noted that although not shown in the figure, the heating of the above-mentioned separation membrane does not necessarily need to be carried out at the most upstream of the series-connected separation membranes, and it can also be carried out in the middle of the series connection.

[0033] The separation membrane complex can be configured in a cylindrical shape. If the gas to be treated is introduced into the inner side of the cylindrical structure of the separation membrane complex at a given gas introduction pressure (for example, 0.5 MPa or more), the gas that has passed through the separation membrane complex (substantially the separation membrane) can be sent out from the surface of the separation membrane complex. On the other hand, the gas that has not passed through can be made to pass along the length direction of the cylindrical separation membrane complex. As a result, the separation of the mixed gas can be carried out. The separation membrane complex can be composed of a single cylindrical structure or multiple cylindrical structures. Preferably, the separation membrane complex has a plurality of cylindrical compartments that penetrate in the length direction.

[0034] Figure 3 It is a schematic explanatory diagram showing the structure of the separation membrane complex in one embodiment of the present invention. Figure 4It is a schematic cross-sectional view showing the structure of the separation membrane composite in one embodiment of the present invention. In the separation membrane composite 10, a plurality of compartments 11 are formed. The compartments 11 are formed in a cylindrical shape so as to penetrate the separation membrane composite 10 in the longitudinal direction. The compartments 11 can serve as flow paths for the gas to be treated. The separation membrane composite 10 includes a porous substrate 1 and a separation membrane 2 provided on the porous substrate 1. The separation membrane 2 can be provided so as to cover substantially the entire inner surface of the porous substrate 1. The gas (permeate gas) in the gas to be treated passing through the compartments 11 and having a high permeability with respect to the separation membrane 2 permeates through the separation membrane composite 10 and is sent out from the side surface 13 of the separation membrane composite 10. On the other hand, the gas (non-permeate gas) having a low permeability with respect to the separation membrane 2 is sent out through the flow path of the compartments 11. Although not shown, the above separation membrane composite can be used by being housed in any appropriate outer cylinder.

[0035] The length of the separation membrane composite is, for example, 10 cm to 200 cm. The outer diameter of the separation membrane composite is, for example, 0.5 cm to 30 cm. The distance between the central axes of adjacent compartments is, for example, 0.3 mm to 10 mm. The inner diameter of the compartments is, for example, 1 mm to 10 mm.

[0036] The above separation membrane system 100 may include a plurality of separation membrane composites 10. The plurality of separation membrane composites 10 can be arranged in series, in parallel, or in a combination of series and parallel. When the separation membrane composites 10 are arranged in parallel, the parallel separation membrane composites 10 can be operated simultaneously or not simultaneously. In one embodiment, the separation membrane composite operated for gas separation is arranged in parallel with the separation membrane composite for regeneration of the separation membrane as described above. In addition, a combustible gas can be obtained individually from the plurality of separation membrane composites 10, or as Figure 1 shown, a plurality of separation membrane composites 10 can be combined to obtain a combustible gas.

[0037] In one embodiment, a method for separating a mixed gas of a combustible gas and a non-combustible gas using the above separation membrane system is provided. This method is a gas separation method for separating a mixed gas of a combustible gas and a non-combustible gas based on permeability, and includes a step of separating the mixed gas into a combustible gas enriched gas and a non-combustible gas enriched gas using the above separation membrane that preferentially permeates the combustible gas or the non-combustible gas, and the non-combustible gas enriched gas can be burned.

[0038] B. Separation Membrane As described above, the separation membrane preferentially permeates either the combustible gas or the non-combustible gas from the gas to be treated (a mixed gas of a combustible gas and a non-combustible gas). Typically, the separation of the mixed gas is carried out by utilizing the difference in permeability with respect to the separation membrane having fine pores. For example, by means of the so-called molecular sieve action that controls permeability depending on the molecular size of the gas and the fine pore diameter of the separation membrane, the gas to be treated is separated into a permeated gas and a non-permeated gas.

[0039] Preferably, the above separation membrane is an inorganic membrane. Examples of the material constituting the separation membrane include zeolite, alumina, titanium dioxide, silica, cordierite, zirconia, mullite, and the like.

[0040] In one embodiment, a zeolite membrane is used as the above separation membrane. The zeolite membrane is formed by forming zeolite into a film on the surface of a porous substrate. The zeolite membrane may contain two or more types of zeolites having different structures and compositions.

[0041] The zeolite constituting the above zeolite membrane can be a zeolite such as the following: a zeolite in which the atom (T atom) located at the center of the oxygen tetrahedron (TO 4 ) contains only Si or contains Si and Al; an AlPO-type zeolite in which the T atom contains Al and P; a SAPO-type zeolite in which the T atom contains Si, Al, and P; a MAPSO-type zeolite in which the T atom contains magnesium (Mg), Si, Al, and P; a ZnAPSO-type zeolite in which the T atom contains zinc (Zn), Si, Al, and P. A part of the T atom can be replaced by other elements.

[0042] Examples of the above zeolite include zeolites such as AEI type, AEN type, AFN type, AFV type, AFX type, BEA type, CHA type, DDR type, ERI type, ETL type, FAU type (X type, Y type), GIS type, LEV type, LTA type, MEL type, MFI type, MOR type, PAU type, RHO type, SAT type, SOD type, etc. The maximum ring number of the zeolite is preferably 12 or less, more preferably 10 or less, and further preferably 8 or less. In addition, it is preferably 6 or more, and further preferably 8 or more.

[0043] The above zeolite membrane contains, for example, Si. The zeolite membrane may contain, for example, any two or more of Si, Al, and P. The zeolite membrane may contain an alkali metal. The alkali metal is, for example, sodium (Na) or potassium (K). When the zeolite membrane contains Si atoms and Al atoms, the Si / Al ratio in the zeolite membrane is, for example, 1 or more and 100,000 or less. The Si / Al ratio is the molar ratio of the Si element contained in the zeolite membrane to the Al element. The Si / Al ratio is preferably 5 or more, more preferably 20 or more, further preferably 100 or more, and the higher the better. By adjusting the mixing ratio of the Si source and the Al source in the raw material solution described later, etc., the Si / Al ratio in the zeolite membrane can be adjusted.

[0044] The average pore diameter of the above separation membrane is, for example, 0.2 nm to 1 nm, and more preferably 0.3 nm to 0.5 nm. The pore diameter of the separation membrane can be adjusted according to the composition of the gas to be permeated as desired. If the average pore diameter of the separation membrane is decreased, the selectivity becomes higher. The average pore diameter of the separation membrane is smaller than the average pore diameter of the porous substrate. When the separation membrane is a zeolite membrane, the maximum ring number of the zeolite is set to n, and the arithmetic mean of the short diameter and the long diameter of the n-ring pore is taken as the average pore diameter. The n-ring pore refers to a pore in which the number of oxygen atoms forming a ring structure by bonding with T atoms is n. When there are a plurality of n-ring pores with the same n, the arithmetic mean of the short diameter and the long diameter of all the n-ring pores is taken as the average pore diameter of the zeolite. The average pore diameter of the zeolite membrane is determined by the framework structure of the zeolite and can be obtained from the values disclosed in the "Database of Zeolite Structures" [online] of the International Zeolite Association, Internet <URL: http: / / www.iza-structure.org / databases / >.

[0045] The thickness of the separation membrane is, for example, 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm, and further preferably 0.5 μm to 10 μm. If the separation membrane is made thicker, the selectivity becomes higher. If the separation membrane is made thinner, the permeation rate increases.

[0046] The surface roughness (Ra) of the separation membrane is, for example, 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, and further preferably 0.5 μm or less. In this specification, the surface roughness (Ra) is the arithmetic surface roughness Ra measured according to JIS B 0601.

[0047] The separation membrane can be formed by any suitable method according to the materials constituting the membrane. For example, a zeolite membrane can be obtained as follows: Zeolite as a seed is coated on a porous substrate, the porous substrate with the attached seed is immersed in a raw material solution, and zeolite is grown with the seed as the nucleus by hydrothermal synthesis. The raw material solution contains, for example, a silica source, an alumina source, an organic substance, an alkali source, water, etc. The heating temperature in hydrothermal synthesis is set, for example, to 60°C to 200°C. The heating time is set, for example, to 1 hour to 240 hours. In addition, a raw material slurry obtained by mixing an organic binder, a ceramic raw material, and a solvent can also be used to form the separation membrane.

[0048] In one embodiment, the combustibility of the non-flammable gas concentrated gas, that is, the composition of the permeating gas and the non-permeating gas, can be controlled by adjusting the separation accuracy (gas selectivity) through the temperature of the separation membrane using a separation membrane having a structure corresponding to the gas to be treated. In one embodiment, by increasing the temperature of the separation membrane, the concentration of the non-flammable gas in the non-flammable gas concentrated gas as the permeating gas can be reduced. For example, in the case of using the DDR-type zeolite membrane described in International Publication No. 2011 / 105511, the concentration of carbon dioxide (non-flammable gas) in the permeating gas containing carbon dioxide can be reduced.

[0049] In addition, it is also possible to obtain a combustible non-flammable gas concentrated gas by using a plurality of separation membrane complexes having different gas permeation characteristics and mixing the non-flammable gas concentrated gases as the permeating gas or the non-permeating gas sent out from each separation membrane complex. When using a plurality of separation membrane complexes, the permeating gas or the non-permeating gas sent out from a part of the separation membrane complexes can be mixed to obtain a combustible non-flammable gas concentrated gas ( Figure 1 of (e), Figure 1 of (f)), or the permeating gas or the non-permeating gas sent out from all the separation membrane complexes can be mixed to obtain a combustible non-flammable gas concentrated gas.

[0050] C. Porous substrate The porous substrate is configured to allow gas to permeate. In the Figure 3 example shown, the porous substrate 1 is a so-called monolithic substrate in which a plurality of through holes extending in the length direction are provided in a columnar main body integrally formed. In the Figure 3In the example shown, the porous substrate 1 is substantially cylindrical. The cross-section of the through-holes perpendicular to the longitudinal direction is, for example, substantially circular. A separation membrane is formed on the inner side surface of the through-holes, and a separation membrane composite (porous substrate / separation membrane) having compartments formed therein can be obtained. It should be noted that the shape of the porous substrate is not limited to the above example, and can be, for example, honeycomb-shaped, flat plate-shaped, tubular, cylindrical, columnar or prismatic. In one embodiment, a separation membrane can be formed on the outer side surface of a tubular porous substrate.

[0051] The length of the porous substrate is, for example, 10 cm to 200 cm. The outer diameter of the porous substrate is, for example, 0.5 cm to 30 cm. When the porous substrate has through-holes, the distance between the central axes of adjacent through-holes is, for example, 0.3 mm to 10 mm. When the porous substrate is tubular or cylindrical, the thickness of the porous substrate is, for example, 0.1 mm to 10 mm.

[0052] As the material of the porous substrate, any suitable material can be used. In one embodiment, the porous substrate is formed of a ceramic sintered body. Examples of the ceramic sintered body selected as the material of the porous substrate include alumina, silica, mullite, zirconia, titanium dioxide, yttrium oxide, silicon nitride, silicon carbide, etc.

[0053] The porous substrate may contain an inorganic binder material. As the inorganic binder material, at least one of titanium dioxide, mullite, easily sinterable alumina, silica, frit, clay mineral, and easily sinterable cordierite can be used.

[0054] The porous substrate may be a single-layer structure or a multi-layer structure. In one embodiment, as Figure 4 shown, the porous substrate is a multi-layer structure formed of layers with different fine pore diameters. It is preferred that the fine pore diameter is smaller the closer to the inside (i.e., the separation membrane side).

[0055] The average fine pore diameter of the porous substrate is, for example, 0.01 μm to 70 μm, preferably 0.05 μm to 25 μm. The average fine pore diameter of the porous substrate on the separation membrane side is 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. Regarding the distribution of the fine pore diameters of the entire porous substrate including the surface and the inside, D5 is, for example, 0.01 μm to 50 μm, D50 is, for example, 0.05 μm to 70 μm, and D95 is, for example, 0.1 μm to 2000 μm. The porosity of the porous substrate on the separation membrane side is, for example, 25% to 50%. The average fine pore diameter of the porous substrate can be measured by a mercury porosimeter, a fine pore diameter distribution measuring device, a nano-sized fine pore diameter distribution measuring device (Japanese: ナノパームポロメータ), etc.

[0056] Industrial Applicability The separation membrane system of the present invention can preferably be used in the process of separating components in a mixed gas.

[0057] Symbol Explanation 1: Porous substrate 2: Separation membrane 10: Separation membrane complex.

Claims

1. A separation membrane system that separates a mixed gas of combustible gas and non-combustible gas based on permeability, wherein, the separation membrane system includes a separation membrane that preferentially permeates the combustible gas or the non-combustible gas, separating the mixed gas into a combustible gas enriched gas and a non-combustible gas enriched gas, and the non-combustible gas enriched gas can burn.

2. The separation membrane system according to claim 1, wherein, a removal mechanism for impurity components is provided upstream of the separation membrane.

3. The separation membrane system according to claim 1, wherein, the non-combustible gas enriched gas contains nitrogen.

4. The separation membrane system according to claim 2, wherein, the non-combustible gas enriched gas contains nitrogen.

5. The separation membrane system according to any one of claims 1 to 4, wherein, the main component of the non-combustible gas in the non-combustible gas enriched gas is nitrogen.

6. The separation membrane system according to any one of claims 1 to 4, wherein, the non-combustible gas enriched gas is used for temperature regulation of the separation membrane.

7. The separation membrane system according to any one of claims 1 to 4, wherein, the non-combustible gas enriched gas is used for heating other separation membranes.

8. The separation membrane system according to any one of claims 1 to 4, wherein, a part of the mixed gas is used for temperature regulation of the separation membrane.

9. The separation membrane system according to any one of claims 1 to 4, wherein, the combustible gas enriched gas is used for temperature regulation of the separation membrane.

Images