Separation film system and method for increasing temperature of separation film

Abstract

Provided is a separation film system comprising a separation film, said separation film system being able to detect any abnormality of the separation film with high sensitivity at an early stage.　A separation film system according to an embodiment of the present invention comprises a supply line that supplies a gas mixture of a polar gas and a non-polar gas to a separation film, and a measuring instrument that measures the flow rate of non-polar gas that has permeated through the separation film. In the above separation film system, the gas mixture may be a heated gas.

Description

Separation membrane system and method for increasing temperature of separation membrane

[0001] The present invention relates to a separation membrane system and a method for increasing the temperature of a separation membrane.

[0002] Various methods have been studied for separating a desired component from a fluid containing two or more components. For example, a method using a separation membrane that selectively allows a specific component to permeate has been known. In such separation membrane methods, abnormalities (e.g., seal leaks, defect leaks, membrane rupture) may occur in the separation membrane during preparation for use and / or during use, and early detection of such abnormalities with high sensitivity is required.

[0003] JP 2017-087192 A International Publication No. 2014 / 050702 Pamphlet

[0004] A primary object of the present invention is to provide a separation membrane system equipped with a separation membrane, which is capable of detecting abnormalities in the separation membrane with high sensitivity and at an early stage.

[0005] [1] A separation membrane system according to an embodiment of the present invention comprises a supply line for supplying a mixed gas of a polar gas and a non-polar gas to a separation membrane, and a measuring device for measuring the flow rate of the non-polar gas that has permeated the separation membrane. [2] In the separation membrane system of [1] above, the mixed gas may be a heated gas. [3] In the separation membrane system of [2] above, the separation membrane system may comprise a heating device upstream of the separation membrane. [4] In the separation membrane system of any of [1] to [3] above, the separation membrane may be a zeolite membrane. [5] A method for increasing the temperature of a separation membrane according to an embodiment of the present invention comprises the steps of supplying a heated mixed gas of a polar gas and a non-polar gas to a separation membrane, and measuring the flow rate of the non-polar gas that has permeated the separation membrane. [6] In the method for increasing the temperature of a separation membrane of [5] above, the concentration of the non-polar gas supplied to the separation membrane may be less than 50% by volume. [7] In the method for increasing the temperature of a separation membrane according to the above [5] or [6], the concentration of the non-polar gas supplied to the separation membrane may be less than 25% by volume.

[0006] According to an embodiment of the present invention, it is possible to provide a separation membrane system that includes a separation membrane and that is capable of detecting abnormalities in the separation membrane with high sensitivity and early detection.

[0007] The present invention relates to a separation membrane system, a method for manufacturing a separation membrane composite, and a method for manufacturing a separation membrane composite.

[0008] A. Separation Membrane System FIG. 1 is an explanatory diagram showing an overview of a separation membrane system according to one embodiment of the present invention. The separation membrane system 100 includes a supply line 20 that supplies a mixed gas of a polar gas and a non-polar gas to a separation membrane 1, and a measuring instrument 30 that measures the flow rate of the non-polar gas that has permeated the separation membrane 1. In one embodiment, the separation membrane may constitute a separation membrane composite 10. The separation membrane 1 can separate a mixed fluid supplied to the separation membrane based on its permeability. FIG. 1 schematically shows an embodiment in which the mixed gas is supplied to a cylindrical separation membrane 1, and the flow rate of the non-polar gas in the gas that has permeated the separation membrane (permeated gas) is measured by a measuring instrument 30. In this specification, a polar gas is a gas containing molecules made up of atoms of different types with different electronegativities. Examples of polar gases include CO ２ , N.H. ３ , H ２ Examples of non-polar gases include O, CO, etc. Non-polar gases are gases that are composed of monoatomic molecules or molecules made up of atoms of the same type with equal electronegativity. Examples of non-polar gases include He, H ２ , N ２ In one embodiment, a polar gas may be a gas composed of polar molecules, and a non-polar gas may be a gas composed of non-polar molecules. In other words, in one embodiment, a polar gas may be a gas whose constituent molecules have an electric dipole moment, and a non-polar gas may be a gas whose constituent molecules do not have an electric dipole moment.

[0009] In the separation membrane system, the flow rate of the nonpolar gas permeated through the separation membrane can be measured, and therefore, an abnormality in the separation membrane can be detected from the flow rate of the nonpolar gas. Specifically, if the flow rate of the nonpolar gas permeated through the separation membrane is greater than a predetermined value, it can be determined that an abnormality such as a seal leak or membrane crack has occurred. Furthermore, if the flow rate of the nonpolar gas is less than a predetermined value, it can be determined that an abnormality such as clogging or deterioration of the membrane material has occurred. Since nonpolar gases have a small contribution of adsorption to the permeability of the separation membrane, the temperature dependence of the permeation rate is low, and there is a strong correlation between abnormalities in the separation membrane permeation flow rate and abnormalities in the separation membrane. Therefore, by supplying a mixed gas containing a nonpolar gas to the separation membrane and measuring the flow rate of the nonpolar gas, abnormalities in the separation membrane can be detected with high sensitivity and early detection. In particular, as described below, the effects of such embodiments of the present invention are remarkable when heated gas is used as the mixed gas.

[0010] In one embodiment, the mixed gas supplied to the separation membrane may be a heated gas. In this embodiment, typically, any suitable heating device (not shown) may be provided upstream of the separation membrane. For example, the supply line may be provided with any suitable heating device (not shown). In this specification, a heated gas refers to a gas at room temperature or higher, for example, a gas at 100°C or higher, preferably 120°C or higher, and more preferably 150°C or higher.

[0011] In one embodiment, the temperature of the separation membrane is increased by the heated mixed gas. Polar gases have a high affinity and adsorption to separation membranes, and therefore, by using a gas containing a polar gas as the mixed gas, the separation membrane can be heated efficiently. On the other hand, the temperature dependence of the separation membrane permeability of polar gases is high, making it difficult to detect an abnormality in the separation membrane from the flow rate of the polar gas passing through the separation membrane. In the present invention, by configuring a mixed gas of a polar gas and a non-polar gas to be supplied to the separation membrane, abnormalities in the separation membrane can be detected with high sensitivity and early detection, as described above.

[0012] Examples of non-polar gases include He and H. ２ , N ２From the viewpoint of low adsorption to the separation membrane and low dependency of separation membrane permeability on temperature, He, H ２ is preferably used. The concentration of the nonpolar gas in the mixed gas supplied to the separation membrane is not particularly limited, but is preferably a concentration that can be accurately measured by an analyzer. In one embodiment, the concentration of the nonpolar gas in the mixed gas supplied to the separation membrane can be 0.001% by volume or more. At such a concentration, the concentration can be preferably measured by, for example, GC-TCD. In one embodiment, the concentration of the nonpolar gas in the mixed gas supplied to the separation membrane can be 1% by volume or more. At such a concentration, the concentration can be preferably measured by, for example, online measurement using a thermal conductivity gas analyzer. Furthermore, the concentration of the nonpolar gas in the mixed gas supplied to the separation membrane is preferably 50% by volume or less, more preferably less than 50% by volume, even more preferably less than 25% by volume, and particularly preferably less than 10% by volume. Within such a range, the effects of the present invention can be exhibited while efficiently heating the separation membrane with the polar gas.

[0013] The non-polar gas preferably has a kinetic molecular diameter smaller than the average pore size of the separation membrane, since such gases easily permeate the separation membrane, and the effects of the present invention are more pronounced.

[0014] The gas used as the non-polar gas has a permeation rate (mol / m ２ / s / Pa) is the permeation rate (mol / m ２ When the pressure (p / s / Pa) is P200, the rate of change in permeation rate represented by |P100 - P200| / P100 is preferably 0.6 or less. Within this range, the effects of the above-described embodiment of the present invention become significant. The permeation rate can be calculated by introducing the gas to be measured into the primary side of the separation membrane at 100 kPaG and measuring the permeation flow rate when the secondary side of the separation membrane is maintained at 0 kPaG. At this time, P100 and P200 can be measured by controlling the temperature of the separation membrane to 100°C and 200°C.

[0015] Examples of polar gases include CO２ The concentration of the polar gas in the mixed gas supplied to the separation membrane is preferably higher than 50% by volume. Within this range, the effect of the present invention can be exerted while efficiently heating the separation membrane with the polar gas.

[0016] In one embodiment, the separation membrane composite can be configured in a cylindrical shape. When a fluid to be treated is introduced into the cylindrical structure of the separation membrane composite at a predetermined introduction pressure (e.g., 0.5 MPa or more), the fluid that permeates the separation membrane composite (essentially the separation membrane) is discharged from the surface of the separation membrane composite, while the fluid that does not permeate can be passed in the longitudinal direction of the cylindrical separation membrane composite, thereby enabling separation of the fluid to be treated. The separation membrane composite may be configured with a single cylindrical structure or multiple cylindrical structures. Preferably, the separation membrane composite has multiple cylindrical cells that penetrate in the longitudinal direction.

[0017] FIG. 2 is an explanatory diagram showing an outline of the configuration of a separation membrane composite according to one embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing the configuration of a separation membrane composite according to one embodiment of the present invention. A plurality of cells 11 are formed in a separation membrane composite 10. The cells 11 are formed in a cylindrical shape so as to penetrate the separation membrane composite 10 in the longitudinal direction. The cells 11 can serve as flow paths for a fluid to be treated. The separation membrane composite 10 includes a separation membrane 1, which is provided on a porous substrate 2. In one embodiment, the separation membrane 1 can be provided so as to cover substantially the entire inner surface (i.e., the cell side surface) of the porous substrate 2. Of the fluid to be treated that passes through the cells 11, a fluid having high permeability to the separation membrane 1 (permeating fluid) permeates the separation membrane composite 10 and is delivered from a side surface 13 of the separation membrane composite 10. On the other hand, a fluid having low permeability to the separation membrane 1 (non-permeating fluid) passes through the flow path of the cells 11 and is delivered. Although not shown, the separation membrane composite can be housed in any suitable outer cylinder for use.

[0018] In order to achieve the above-described separation function, it is preferable to raise the temperature of the separation membrane composite 10 (essentially the separation membrane 1) before supplying the fluid to be treated. If a mixed gas of a polar gas and a non-polar gas is supplied to the separation membrane 1 as described above during this temperature increase, the temperature of the separation membrane can be raised efficiently and abnormalities in the separation membrane can be detected early and with high sensitivity. The mixed gas of a polar gas and a non-polar gas may be a gas composed of the same components as the fluid to be treated, or may be a gas composed of different components.

[0019] 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 cells is, for example, 0.3 mm to 10 mm. The inner diameter of the cell is, for example, 1 mm to 10 mm.

[0020] (Separation Membrane) In one embodiment, the separation membrane can separate mixed fluids by utilizing the difference in permeability through the separation membrane having micropores. For example, the fluid to be treated can be separated by the so-called molecular sieve action, in which permeability is controlled depending on the size of the molecules constituting the fluid and the pore size of the separation membrane.

[0021] Preferably, the separation membrane is an inorganic membrane. Examples of materials constituting the separation membrane include zeolite, silica, and carbon. Separation membranes made of inorganic membranes tend to be more susceptible to abnormalities because they are used at high temperatures. However, by using the separation membrane system, abnormalities in the separation membrane can be detected early and with high sensitivity.

[0022] In one embodiment, a zeolite membrane is used as the separation membrane. The zeolite membrane is formed by forming a film of zeolite on the surface of a porous substrate. The zeolite membrane may contain two or more types of zeolite with different structures or compositions.

[0023] The zeolite constituting the zeolite membrane is an oxygen tetrahedron (TO ４Zeolites in which the atom (T atom) located at the center of the zeolite (T atom) is composed of only Si or Si and Al, AlPO zeolites in which the T atoms are composed of Al and P, SAPO zeolites in which the T atoms are composed of Si, Al, and P, MAPSO zeolites in which the T atoms are composed of magnesium (Mg), Si, Al, and P, and ZnAPSO zeolites in which the T atoms are composed of zinc (Zn), Si, Al, and P can be used. Some of the T atoms may be substituted with other elements.

[0024] Examples of the zeolite include 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, and SOD type zeolites. The maximum number of rings in the zeolite is preferably 12 or less, more preferably 10 or less, and even more preferably 8 or less. Also, it is preferably 6 or more, and even more preferably 8 or more.

[0025] The 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 Si to Al contained in the zeolite membrane. The Si / Al ratio is preferably 5 or more, more preferably 20 or more, and even more preferably 100 or more, and the higher the Si / Al ratio, the better. The Si / Al ratio in the zeolite membrane can be adjusted by adjusting the compounding ratio of the Si source and the Al source in the raw material solution, which will be described later.

[0026] The average pore diameter of the 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 depending on the desired composition of the permeating fluid. Reducing the average pore diameter of the separation membrane increases selectivity. 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 number of rings in the zeolite is n, and the average pore diameter is the arithmetic mean of the minor and major axes of the n-membered ring pores. An n-membered ring pore is a pore in which the number of oxygen atoms in the portion where an oxygen atom is bonded to a T atom to form a ring structure is n. When there are multiple n-membered ring pores with the same n, the arithmetic mean of the minor and major axes of all the n-membered ring pores is the average pore diameter of the zeolite. The average pore size of a zeolite membrane is determined by the skeletal structure of the zeolite, and can be determined from values ​​disclosed in the International Zeolite Society's "Database of Zeolite Structures" [online] on the Internet at <URL: http: / / www.iza-structure.org / databases / >. It can also be estimated by measuring the permeability of gases with different molecular diameters. Examples of such methods include those described in JP 2008-247654 A.

[0027] The thickness of the separation membrane is, for example, 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm, and more preferably 0.5 μm to 10 μm. A thicker separation membrane increases selectivity. A thinner separation membrane increases permeation rate.

[0028] 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 even more preferably 0.5 μm or less. In this specification, the surface roughness (Ra) is the arithmetic surface roughness Ra measured in accordance with JIS B 0601.

[0029] The separation membrane can be formed by any appropriate method depending on the material constituting the membrane. For example, a zeolite membrane can be obtained by applying zeolite as seed crystals to a porous substrate, immersing the porous substrate with the seed crystals attached in a raw material solution, and growing zeolite using the seed crystals as nuclei 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 the hydrothermal synthesis is, for example, 60°C to 200°C. The heating time is, for example, 1 hour to 240 hours. Alternatively, the separation membrane may be formed using a raw material slurry obtained by mixing an organic binder, a ceramic raw material, and a solvent.

[0030] (Porous substrate) The porous substrate is configured to be gas permeable. In the example shown in FIG. 2, the porous substrate 12 is a so-called monolithic substrate in which a plurality of through holes extending in the longitudinal direction are provided in an integrally molded, continuous columnar body. In the example shown in FIG. 2, the porous substrate 12 is approximately cylindrical. The cross section perpendicular to the longitudinal direction of the through holes is, for example, approximately circular. A separation membrane can be formed on the inner surface of the through holes to obtain a separation membrane composite (porous substrate / separation membrane) in which cells are formed. The shape of the porous substrate is not limited to the above example, and may be, for example, a honeycomb shape, a flat plate shape, a tubular shape, a cylindrical shape, a columnar shape, or a polygonal columnar shape. In one embodiment, a separation membrane may be formed on the outer surface of a tubular porous substrate.

[0031] 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.

[0032] The porous substrate may be made of any suitable material. In one embodiment, the porous substrate is made of a sintered ceramic body. Examples of sintered ceramic bodies that can be used as the porous substrate material include alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide.

[0033] The porous substrate may contain an inorganic binder, which may be at least one of titania, mullite, sinterable alumina, silica, glass frit, clay minerals, and sinterable cordierite.

[0034] The porous substrate may have a single layer structure or a multilayer structure. In one embodiment, the porous substrate has a multilayer structure with layers having different pore sizes, as shown in Figure 3. It is preferable that the pore size is smaller as it approaches the inside (i.e., the separation membrane side).

[0035] The average pore diameter of the porous substrate is, for example, 0.01 μm to 70 μm, preferably 0.05 μm to 25 μm. The average 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. With regard to the pore size distribution throughout the porous substrate, including the surface and interior, 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 pore diameter of the porous substrate can be measured using a mercury porosimeter, perm porometer, nanoperm porometer, or the like.

[0036] (Measuring Instrument for Measuring the Flow Rate of Nonpolar Gas) As the measuring instrument for measuring the flow rate of the nonpolar gas, any appropriate measuring instrument can be used depending on the type of nonpolar gas used. For example, the flow rate of the permeated nonpolar gas can be measured by measuring the flow rate of the permeated gas using a mass flow meter and measuring the concentration of the nonpolar gas in the permeated gas using a gas chromatograph.

[0037] The separation membrane system may further include any appropriate element. For example, it may include a supply unit for supplying a fluid, a recovery unit for recovering the fluid after passing through the separation membrane composite, a pressure adjustment unit for adjusting the pressure of the fluid flow path, etc. The configuration of the separation membrane system is described, for example, in International Publication No. 2018 / 225325. The description of this publication is incorporated herein by reference.

[0038] B. Method for Raising the Temperature of a Separation Membrane One embodiment of the present invention provides a method for raising the temperature of a separation membrane, comprising the steps of: supplying a heated mixed gas of a polar gas and a non-polar gas to a separation membrane; and measuring the flow rate of the non-polar gas that has permeated the separation membrane. As described above, the use of a mixed gas of a polar gas and a non-polar gas makes it possible to efficiently raise the temperature of the separation membrane and to detect abnormalities in the separation membrane at an early stage with high sensitivity.

[0039] The concentration of the non-polar gas supplied to the separation membrane may be as described in Section A.

[0040] The separation membrane may have the configuration described in Section A. In one embodiment, as described above, the separation membrane may constitute a separation membrane complex.

[0041] The flow rate of the mixed gas supplied to the separation membrane may be any appropriate flow rate.

[0042] For example, the permeation flow rate of the non-polar gas when the separation membrane is normal is measured (or predicted) in advance, and this flow rate is set as the normal flow rate. Then, an abnormality in the separation membrane can be detected by comparing the normal flow rate with the flow rate measured in step II.

[0043] The separation membrane system of the present invention can be suitably used in a process for separating components in a mixed gas.

[0044] 1 Separation membrane 2 Porous base material 10 Separation membrane composite

Claims

1. a supply line for supplying a mixed gas of a polar gas and a non-polar gas to the separation membrane; a measuring device for measuring the flow rate of the non-polar gas that has permeated the separation membrane; the mixed gas is a superheated gas, The temperature of the mixed gas is 100°C or higher. Separation membrane system.

2. The separation membrane system according to claim 1 , further comprising a heating device upstream of the separation membrane.

3. The separation membrane system according to claim 1 or 2, wherein the separation membrane is a zeolite membrane.

4. supplying a heated mixture of a polar gas and a non-polar gas to a separation membrane; and measuring the flow rate of the non-polar gas that has permeated the separation membrane; In the step of supplying the heated mixed gas to the separation membrane, the temperature of the separation membrane is increased. Method for increasing the temperature of the separation membrane.

5. 5. The method for increasing the temperature of a separation membrane according to claim 4, wherein the concentration of the non-polar gas supplied to the separation membrane is less than 50% by volume.

6. 5. The method for increasing the temperature of a separation membrane according to claim 4, wherein the concentration of the non-polar gas supplied to the separation membrane is less than 25% by volume.