Method for stopping separation device
Patent Information
- Application Number
- JP2024574364
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Priority Date
- 2024-01-11
- Filing Date
- 2024-01-11
- Publication Date
- 2025-09-19
Abstract
Description
How to stop the separator
[0001] The present invention relates to a method for stopping a separating device.
[0002] Membrane separation methods are known that use separation membranes to separate specific substances from a mixture. For example, a separation method using a zeolite membrane has been proposed (see Non-Patent Document 1). In separation devices equipped with separation membranes, the separation membranes are sometimes heated under pressure to ensure that they can perform their intended functions. In such separation devices, it is necessary to prevent damage to the separation membranes due to temperature drops when the separation device is stopped.
[0003] Development of a Membrane-Assisted Reactor, Mitsui Zosen Technical Report, February 2003, No. 178, 115-120
[0004] A primary object of the present invention is to provide a method for shutting down a separation apparatus equipped with a separation membrane, which method can prevent damage to the separation membrane.
[0005] [1] A method for shutting down a separation device according to an embodiment of the present invention is a method for shutting down a separation device having a separation membrane after a dehydration process using the separation membrane, comprising: ２ O) and saturated water vapor pressure P ｓａｔ (H ２ O) and [P(H ２ O) / P ｓａｔ (H ２and placing the separation membrane in environment A, where the environment A satisfies the relationship [Ratio (Ratio of the total pressure of the separation membrane to the total pressure of the environment A) > 0.001] and has a temperature of 100°C or higher, and lowering the temperature of the environment A. [2] The method for shutting down a separation apparatus according to [1] above may include reducing the pressure of the environment A. [3] The method for shutting down a separation apparatus according to [2] above may include reducing the pressure of the environment A and then lowering the temperature. [4] In the method for shutting down a separation apparatus according to any of [1] to [3] above, the temperature reduction may be performed by adjusting the output of a temperature adjustment means. [5] The method for shutting down a separation apparatus according to any of [2] to [4] above may include maintaining the temperature of the environment A at a substantially constant level during the reduction in pressure. [6] The method for shutting down a separation apparatus according to any of [2] to [5] above may include performing the reduction in pressure stepwise. [7] The method for shutting down a separation apparatus according to any of [1] to [6] above may include maintaining the total pressure of the environment A at a substantially constant level during the reduction in temperature. [8] In the method for shutting down a separation apparatus according to any one of [1] to [7] above, the temperature of the environment A may be less than 400° C. [9] In the method for shutting down a separation apparatus according to any one of [1] to [8] above, in the environment A, the water vapor partial pressure P(H ２ O) and the saturated water vapor pressure P ｓａｔ (H ２ O) and [1>P(H ２ O) / P ｓａｔ (H ２ 0) may satisfy the relationship.
[10] In the method for shutting down a separation apparatus according to any one of [2] to [9] above, the depressurization operation may be stopped when the total pressure of the environment A reaches atmospheric pressure + 10 kPa.
[11] In the method for shutting down a separation apparatus according to any one of [1] to
[10] above, the separation membrane may be a zeolite membrane.
[12] In the method for shutting down a separation apparatus according to
[11] above, the zeolite membrane may be made of LTA-type zeolite.
[0006] According to an embodiment of the present invention, it is possible to provide a method for stopping a separation apparatus equipped with a separation membrane, which can prevent damage to the separation membrane.
[0007] FIG. 1 is a schematic diagram of a separation membrane composite used in a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 2 is a schematic diagram of the separation membrane and substrate of FIG. 1. FIG. 3A is a graph illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 3B is a graph illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 4 is a graph illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 5 is a graph illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 6 is a graph illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. FIG. 7 is a schematic diagram of a modification of the separation membrane composite. FIG. 8 is a schematic cross-sectional view of the separation membrane composite of FIG. 7. FIG. 9 is a schematic diagram of another modification of the separation membrane composite. FIG. 10 is a schematic diagram illustrating a method for operating a separation apparatus according to one embodiment of the present invention.
[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiment, but these are merely examples and do not limit the interpretation of the present invention.
[0009] A. Method for Shutdown of Separation Apparatus Fig. 1 is a schematic diagram of a separation membrane composite used in a method for shutting down a separation apparatus according to one embodiment of the present invention; Fig. 2 is a schematic diagram of the separation membrane and substrate of Fig. 1 .
[0010] A method for shutting down a separation device according to one embodiment of the present invention is a method for shutting down a separation device 1 having a separation membrane 2. In one embodiment, the separation membrane 2 constitutes a separation membrane composite 10. The separation membrane composite 10 includes the separation membrane 2 and a substrate 3 disposed on one side of the separation membrane 2. The separation device 1 has a first flow path 21 and a second flow path 22. The first flow path 21 is located on the separation membrane 2 side of the separation membrane composite 10. The second flow path 22 is located on the substrate 3 side of the separation membrane composite 10. In one embodiment, the first flow path and the second flow path are separated by the separation membrane. In one embodiment, the first flow path can be a flow path through which a mixed gas to be separated in the dehydration step flows. In one embodiment, the second flow path can be a flow path through which a gas that has permeated the separation membrane flows.
[0011] The method for shutting down the separation device is performed after the dehydration process using the separation membrane 2. In the dehydration process, the water-containing fluid to be treated (e.g., a water-containing gas containing organic compounds) is supplied to the first flow path, and the water is separated by the separation membrane, thereby dehydrating the water-containing fluid. The water-containing fluid may be supplied under pressure. Furthermore, the separation membrane may be heated to a predetermined temperature to exhibit its separation properties.
[0012] The method for stopping the separation device is to ２ The method for stopping the separation device may be a method for lowering the temperature of the separation membrane heated in the dehydration step to a predetermined temperature (e.g., 100°C). In this specification, the water vapor partial pressure P(H ２ O), saturated water vapor pressure P ｓａｔ (H ２ When referring to pressure such as pressure (O), total pressure, etc., the pressure may be the pressure in the first flow path (e.g., the flow path inside the separation membrane) (e.g., the pressure on the outlet side of the flow path), and in the separation membrane composite 10 shown in FIG. 1 , it may be the pressure in the first flow path 21.
[0013] Specifically, the water vapor partial pressure P(H ２ The environment in which the water vapor partial pressure P(H ２ O) and saturated water vapor pressure P ｓａｔ (H ２ O) and [P(H ２O) / P ｓａｔ (H ２ The environment satisfies the relationship [(Ratio of the temperature of the first flow path) to the outside of the first channel] and has a temperature of 100° C. or higher. For convenience, this environment will be referred to as "environment A" in this specification. Environment A may be within the first flow path (e.g., the outlet).
[0014] The temperature of the environment A is preferably less than 400° C., and more preferably not more than 200° C. Within this range, damage to the separation membrane (for example, damage caused by dissolution of the separation membrane) can be prevented.
[0015] 3A and 3B are graphs illustrating a method for shutting down a separation device according to one embodiment of the present invention. In FIGS. 3A and 3B, the vertical axis represents the total pressure in the environment in which the separation membrane is placed, and the horizontal axis represents the temperature. Note that FIG. 3B shows the P(H ２ O) / P ｓａｔ (H ２ In order to make the line of [P(H O )]=0.001 easier to see, FIG. 3A is enlarged in the range of 0 kPa to 30 kPa on the vertical axis. Also, in FIGS. 3A and 3B, the area satisfying the conditions of environment A is colored. While FIGS. 3A and 3B show an example in which the supply steam concentration is 25 mol%, the supply steam concentration is not limited to this and can be any appropriate value. The end point of the dehydration step in the preceding step is set as the start point S of the method for stopping the separation apparatus. In the embodiment shown in FIG. 3, the temperature at the start point S is 150°C and the total pressure is 1000 kPaA. In the embodiment of the present invention, as shown by the arrow in FIG. 3A, [P(H ２ O) / P ｓａｔ (H ２ The temperature of the separation membrane is lowered in an environment where the relationship [(R / R) / (H))≧0.001] is satisfied and the temperature is 100°C or higher. By lowering the temperature of the separation membrane in this manner, drying of the separation membrane can be suppressed and various damages, such as cracks, can be prevented. In one embodiment, the temperature of environment A is lowered by adjusting the output of a temperature adjustment means. Preferably, the temperature of environment A is lowered by supplying a water-containing gas (e.g., water-containing air) whose temperature has been adjusted by a temperature adjustment means to the first flow path.
[0016] In the above environment A, P(H ２ O) / P ｓａｔ (H ２ O) is preferably 0.005 or more, more preferably 0.05 or more. Within such a range, the above effects become significant. Furthermore, the measuring equipment can be simplified. Furthermore, general-purpose measuring equipment can be used, which reduces costs.
[0017] In addition, in the above environment A, P(H ２ O) / P ｓａｔ (H ２ O) is preferably less than 1 (for example, below the dashed line in FIG. 3A ), more preferably 0.95 or less, and even more preferably 0.9 or less. Within such a range, the effects of the present invention can be stably obtained. By making environment A in such a state, damage to the separation membrane due to droplets (for example, damage caused by dissolution of the separation membrane) can be prevented.
[0018] 3A , the method for shutting down the separation apparatus includes reducing the pressure of environment A. In one embodiment, a pressurized environment (e.g., an environment with a pressure of 0.1 MPaG to 20 MPaG) in the previous dehydration step is reduced in pressure in the method for shutting down the separation apparatus. The reduction in pressure may be an operation that reduces the amount of water in environment A.
[0019] 4 and 5 are graphs illustrating a method for shutting down a separation apparatus according to one embodiment of the present invention. In one embodiment, environment A is depressurized and then cooled. Preferably, as shown in FIGS. 4 and 5, environment A is first depressurized at a starting point S of the shutting down method. The temperature of environment A may be lowered during depressurization. For example, a natural decrease in temperature due to depressurization is allowed. In one embodiment, the temperature of environment A is kept substantially constant (for example, a temperature change of within 5°C) during depressurization. This embodiment can prevent damage to the separation membrane due to drying and can also significantly increase the accuracy of preventing damage to the separation membrane due to droplets.
[0020] In one embodiment, the temperature of environment A is lowered and then the pressure is reduced ( FIG. 6 ). In one embodiment, at a starting point S of the stopping method, the temperature of environment A is first lowered. In one embodiment, the pressure of environment A is kept substantially constant (for example, a pressure change of 50 kPa or less) during the temperature lowering. According to this embodiment, it is possible to prevent damage to the separation membrane caused by drying, and also to significantly increase the accuracy of preventing damage to the separation membrane caused by droplets.
[0021] Preferably, even during decompression, a pressure higher than atmospheric pressure is maintained in environment A. This makes it possible to prevent damage to the separation membrane caused by drying.
[0022] In one embodiment, the temperature of environment A is lowered during the depressurization by adjusting the output of a temperature control means. For example, a heating device is used as the temperature control means to mitigate the natural decrease in temperature during the depressurization or to maintain a substantially constant temperature change. Examples of the heating device include a reactor involving a chemical reaction, a heater, and a heat exchanger. In addition, the heating device used in the preceding dehydration step may be diverted to the temperature control means.
[0023] In one embodiment, when depressurizing environment A, the depressurization operation is performed in stages ( FIGS. 4 and 6 ). As used herein, “the depressurization operation is performed in stages” means that two or more (preferably five or more, more preferably 20 or more) periods in which the pressure (total pressure) of environment A is substantially constant (e.g., a pressure change of 50 kPa or less) are provided between the start and end of the method for shutting down the separation apparatus. The upper limit of the number of periods in which the pressure (total pressure) of environment A is substantially constant is, for example, 150 or less. For example, when depressurizing from 3 MPa to 0.1 MPa, the depressurization operation is performed in 58 stages, with a period in which the pressure (total pressure) of environment A is substantially constant every 50 kPa of depressurization. By performing the depressurization operation in stages, damage to the separation membrane can be prevented. In one embodiment, the number of periods in which the pressure (total pressure) of environment A is substantially constant is 10 or less.
[0024] In one embodiment, the method for shutting down the separation apparatus includes keeping the total pressure of the environment A substantially constant (for example, a pressure change of 50 kPa or less) while the temperature of the environment A is decreasing (FIGS. 4 to 6).
[0025] Preferably, in the method for shutting down a separation apparatus, the depressurization operation is stopped when the total pressure of the environment A reaches atmospheric pressure + 10 kPa (preferably + 50 kPa). After the total pressure of the environment A reaches atmospheric pressure + 10 kPa (preferably + 50 kPa), the temperature of the separation membrane is made less than 100°C. In this way, the separation apparatus can be shut down while preventing damage to the separation membrane. In another embodiment, the depressurization operation is stopped when the total pressure of the environment A reaches atmospheric pressure.
[0026] B. Separation Device B-1. Separation Membrane Composite As shown in FIG. 1, a separation device 1 typically includes a separation membrane composite 10 including a substrate 3 and a separation membrane 2. Although not shown, the separation membrane composite 10 is housed in any suitable case before use. The separation membrane composite 10 typically extends in the same direction as the first flow path. The length of the separation membrane composite 10 can be adjusted arbitrarily and appropriately.
[0027] B-1-1. Substrate The substrate 3 supports the separation membrane 2. In one embodiment, the substrate 3 is a porous substrate. The porous substrate has, for example, a monolithic structure and includes a skeleton that is continuous in the form of a three-dimensional network and interconnected pores defined by the skeleton.
[0028] The porous substrate may be made of any suitable material. Typical examples of the material for the porous substrate include ceramic sintered bodies. Examples of ceramic sintered bodies include alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, and cordierite. The ceramic sintered bodies may be used alone or in combination. Of the ceramic sintered bodies, alumina is preferred.
[0029] The porous substrate may contain an inorganic binder. Examples of inorganic binders include titania, mullite, sinterable alumina, silica, glass frit, clay minerals, and sinterable cordierite. The inorganic binders may be used alone or in combination.
[0030] The porous substrate may be composed of a single layer or may have a multilayer structure in which multiple layers are stacked. In one embodiment, the porous substrate has a multilayer structure having multiple layers with different pore sizes, as shown in Figure 2. In this case, it is preferable that the pore size is smaller as the layer is closer to the separation membrane 2.
[0031] 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, for example, using a mercury porosimeter, perm porometer, or nanoperm porometer.
[0032] As shown in FIG. 1 , the substrate 3 typically separates the first flow path 21 and the second flow path 22. The substrate 3 may have any suitable shape. Examples of the shape of the substrate 3 include a cylindrical shape, a honeycomb shape, and a flat plate shape. In one embodiment, the substrate 3 is a cylindrical substrate 3a. Examples of the cross-sectional shape of the cylindrical substrate 3a in a direction perpendicular to the longitudinal direction include a triangle, a rectangle, a pentagon, a polygon having hexagons or more, a circle, and an ellipse, and a circle is preferred. The outer diameter and length of the cylindrical substrate can be appropriately set depending on the purpose.
[0033] In this embodiment, the internal space of the cylindrical substrate 3a (the space defined by the inner peripheral surface of the cylindrical substrate) includes either the first flow path 21 or the second flow path 22, and the external space of the cylindrical substrate 3a (the space outside the outer peripheral surface of the cylindrical substrate) includes the other of the first flow path 21 or the second flow path 22. In the illustrated example, the internal space of the cylindrical substrate 3a includes the first flow path 21, and the external space of the cylindrical substrate 3a includes the second flow path 22.
[0034] 7 and 8, the substrate 3 is a honeycomb substrate 3b. The honeycomb substrate 3b has partition walls 33 that define a plurality of cells 34. The cells 34 are formed in a cylindrical shape so as to penetrate the honeycomb substrate 3b in the length direction.
[0035] The cells 34 extend in the longitudinal direction (axial direction) of the honeycomb substrate 3b from the first end face E1 (inlet end face) to the second end face E2 (outlet end face) of the honeycomb substrate 3b (see FIG. 7). The cells 34 have any appropriate shape in a cross section perpendicular to the longitudinal direction of the honeycomb substrate 3b. Examples of the cross-sectional shape of the cells include triangles, rectangles, pentagons, polygons with hexagons or more, circles, and ellipses. The cross-sectional shapes and sizes of the cells may all be the same, or at least some may be different. Among such cross-sectional shapes of the cells, a circle is preferred.
[0036] The distance between the central axes of the plurality of cells 34 is, for example, 0.3 mm to 20 mm. The cell density in the cross section perpendicular to the longitudinal direction of the honeycomb substrate (i.e., the number of cells 34 per unit area) can be appropriately set depending on the purpose. The cell density is, for example, 0.5 cells / cm. ２ ~320 cells / cm ２ If the cell density is in this range, the strength and effective GSA (geometric surface area) of the honeycomb substrate can be sufficiently ensured.
[0037] The honeycomb substrate 3b may have any suitable shape (overall shape). Examples of the shape of the honeycomb substrate include a cylindrical shape with a circular bottom, an elliptical cylindrical shape with an elliptical bottom, a rectangular prism with a polygonal bottom, and a cylindrical shape with an irregular bottom. The honeycomb substrate 3b in the illustrated example has a cylindrical shape. The outer diameter and length of the honeycomb substrate can be appropriately set depending on the purpose.
[0038] In this embodiment, the internal space of each of the plurality of cells 34 (the space defined by the inner peripheral surface of the cell) includes either the first flow path 21 or the second flow path 22, and the external space of the honeycomb substrate 3 b (the space outside the outer peripheral surface of the honeycomb substrate) includes the other of the first flow path 21 or the second flow path 22. In the illustrated example, the internal space of the cell 34 includes the first flow path 21, and the external space of the honeycomb substrate 3 b includes the second flow path 22.
[0039] B-1-2. Separation Membrane The separation membrane 2 is typically provided directly on the surface of the substrate 3. The separation membrane 2 may face the first flow path 21 (see FIGS. 1 and 8) or the second flow path 22 (see FIG. 9). When the separation membrane faces the first flow path, the substances to be separated contained in the mixture passing through the first flow path come into direct contact with the separation membrane. This allows the separation membrane to efficiently separate the substances to be separated. When the separation membrane faces the second flow path, the substances to be separated contained in the mixture passing through the first flow path permeate the substrate and reach the separation membrane. This also allows the separation membrane to separate the substances to be separated.
[0040] In one embodiment, the separation membrane 2 faces the first flow path 21. In FIG. 1 , the substrate 3 is a cylindrical substrate 3 a, and the separation membrane 2 is formed on the inner surface of the cylindrical substrate 3 a. In the illustrated example, the first flow path 21 is formed in a portion (typically the central portion) of the cross section of the separation membrane composite 10 where the separation membrane 2 is not formed. In FIG. 8 , the substrate 3 is a honeycomb substrate 3 b, and the separation membrane 2 is formed on the inner surface of each of the multiple cells 34. The first flow path 21 is formed in a portion (typically the central portion) of the cross section of the cell 34 where the separation membrane 2 is not formed. As in the illustrated example, the separation membrane 2 may be formed on the entire inner surface of the cylindrical substrate 3 a or the cell 34 (i.e., so as to surround the first flow path 21), or may be formed on a portion of the inner surface of the cylindrical substrate 3 a or the cell 34. When the separation membrane is formed so as to surround the first flow path, the separation efficiency of the target substance can be improved.
[0041] The separation membrane 2 typically has micropores. The separation membrane 2 separates a mixture into separated substances and non-separated substances by, for example, a so-called molecular sieve action, which controls the separation characteristics of specific substances depending on the molecular size and the pore diameter of the separation membrane.
[0042] The separation membrane 2 may be made of any suitable material, such as zeolite, silica, or carbon. The membrane materials may be used alone or in combination.
[0043] When the substance to be separated contains water, zeolite is preferably used as the material of the separation membrane 2. In one embodiment, the separation membrane 2 is a zeolite membrane.
[0044] The zeolite membrane is formed by forming a film of zeolite on the surface of a substrate. The zeolite membrane may contain two or more types of zeolite with different structures and compositions.
[0045] As the zeolite constituting the zeolite membrane, for example, oxygen tetrahedron (TO ４) zeolites in which the atom (T atom) located at the center of the zeolite is composed of only Si or of 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. Some of the T atoms may be substituted with other elements.
[0046] Examples of the zeolite include AEI, AEN, AFN, AFV, AFX, BEA, CHA, DDR, ERI, ETL, FAU (X, Y), GIS, LEV, LTA, MEL, MFI, MOR, PAU, RHO, SAT, and SOD types. Among these zeolites, LTA type zeolite is particularly preferred.
[0047] The maximum number of ring members in the zeolite is, for example, 12 or less, preferably 10 or less, more preferably 8 or less, and for example, 6 or more.
[0048] The zeolite membrane is made of SiO ２ and Al ２ O ３ The zeolite membrane may further contain an alkali metal, such as sodium (Na) or potassium (K).
[0049] SiO in zeolite membranes ２ / Al ２ O ３ The molar ratio of SiO in the zeolite membrane is, for example, 100 or less, preferably 10 or less, more preferably less than 5, and even more preferably 4 or less. ２ / Al ２ O ３ When the molar ratio of SiO in the zeolite membrane is equal to or less than the upper limit, the zeolite membrane can be more stably prevented from being damaged. ２ / Al ２ O ３ The lower limit of the molar ratio of SiO is typically 2. ２ / Al ２ O ３The molar ratio can be measured, for example, by scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX; X-ray acceleration voltage 10 kV).
[0050] The average pore diameter of the separation membrane 2 can be arbitrarily and appropriately selected depending on the substance to be separated. The average pore diameter of the separation membrane 2 is, for example, 0.2 nm to 1 nm, and preferably 0.3 nm to 0.5 nm. Reducing the average pore diameter of the separation membrane 2 increases selectivity. The average pore diameter of the separation membrane 2 is smaller than the average pore diameter of the substrate 3. When the separation membrane 2 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 framework structure of the zeolite, and can be determined from the values disclosed in the "Database of Zeolite Structures" [online] of the International Zeolite Society, available on the Internet at <URL: http: / / www.iza-structure.org / databases / >.
[0051] The thickness of the separation membrane 2 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.
[0052] The surface roughness (Ra) of the separation membrane 2 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. The surface roughness (Ra) can be measured, for example, in accordance with JIS B 0601.
[0053] The separation membrane 2 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 separation membrane, immersing the 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, and water. 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.
[0054] B-2. Supply Section, First Recovery Section, and Second Recovery Section In one embodiment, as shown in Figure 10, the separation device 1 further includes, in addition to the separation membrane composite 10, a supply section 4 that supplies a mixture to the first flow path 21 of the separation membrane composite 10; a first recovery section 5 that recovers the fluid that has passed through the first flow path 21; and a second recovery section 6 that recovers the permeated substance that has permeated the separation membrane 2. The separation device 1 in the illustrated example is configured to be able to adjust the temperature, pressure, and flow rate of the mixture passing through the first flow path. Note that Figure 10 illustrates one embodiment of the present invention, and the present invention is not limited thereto.
[0055] The supply unit 4 in the illustrated example is capable of adjusting the temperature and flow rate of the mixture supplied (flowing into) the first flow path 21. The supply unit 4 includes a supply line 41, a heating device 42, and a flow regulator 43. The supply line 41 is a pipe for supplying the mixture to the first flow path 21. The upstream end of the supply line 41 in the supply direction of the mixture is connected to, for example, a storage tank (not shown) that stores the mixture. The downstream end of the supply line 41 in the supply direction of the mixture is connected to the inlet of the first flow path 21 included in the separation membrane composite 10 (see FIG. 1 ). The heating device 42 is provided in the supply line 41 and is capable of heating the mixture passing through the supply line 41. The heating device 42 may have any appropriate configuration. The flow regulator 43 is capable of adjusting the flow rate of the mixture passing through the supply line 41. The flow regulator 43 may have any appropriate configuration. In the illustrated example, the flow regulator 43 is provided in the supply line 41 between the heating device 42 and the separation membrane composite 10. The supply unit 4 may include other devices as necessary. For example, other devices may be present in the supply line 41 between the flow rate regulator 43 and the separation membrane composite 10.
[0056] The first recovery section 5 in the illustrated example is capable of adjusting the pressure in the first flow path 21. The first recovery section 5 includes a first recovery line 51 and a pressure adjustment valve 52. The first recovery line 51 is a pipe through which a fluid (a mixture in which the substance to be separated has been reduced) that has passed through the first flow path 21 of the separation membrane composite 10 passes. The upstream end of the first recovery line 51 in the direction of fluid passage is connected to the outlet of the first flow path 21 of the separation membrane composite 10 (see FIG. 1). The downstream end of the first recovery line 51 in the direction of fluid passage is connected to, for example, a storage tank (not shown). The pressure adjustment valve 52 is provided in the first recovery line 51. The pressure adjustment valve 52 can adjust the aperture of the first recovery line 51, and thus can adjust the pressure in the first flow path 21. The temperature of the environment A can be the temperature at the outlet of the separation membrane (separation membrane composite 10). When the pressure regulating valve 52 is provided, the temperature of the environment A can be measured between the outlet of the separation membrane (separation membrane complex 10) and the pressure regulating valve 52. When the separation membranes are arranged in series and a heating device is further provided downstream of the separation membrane (separation membrane complex 10), the temperature of the environment A can be measured upstream of the heating device. The temperature may be the surface temperature of the pipe.
[0057] The second recovery section 6 in the illustrated example includes a second recovery line 61. The second recovery line 61 is a pipe through which a fluid (fluid containing at least a permeant) that has passed through the second flow path 22 from the second flow path 22 provided in the separation membrane composite 10 passes. The upstream end of the second recovery line 61 in the fluid passage direction is connected to the outlet of the second flow path 22 provided in the separation membrane composite 10. The downstream end of the second recovery line 61 in the fluid passage direction is connected to, for example, a storage tank (not shown).
[0058] In the above-described embodiment, the supply unit 4 upstream of the separation membrane composite 10 adjusts the temperature and flow rate of the mixture supplied (flowing into) the first flow path 21, and the first recovery unit 5 downstream of the separation membrane composite 10 adjusts the pressure of the mixture in the first flow path 21, but the configuration of the separation device 1 is not limited to this. The supply unit 4 may be configured to be able to adjust the pressure of the mixture in the first flow path 21. Furthermore, the first recovery unit 5 may be configured to be able to adjust the flow rate of the mixture passing through the first flow path 21.
[0059] The method for stopping a separation apparatus according to an embodiment of the present invention can be used to separate a specific substance in a mixture, and can be particularly suitably used to separate water from a water-containing mixture.
[0060] REFERENCE SIGNS LIST 1 Separation device 2 Separation membrane 3 Substrate 21 First flow path 22 Second flow path
Claims
1. A method for stopping a separation device having a separation membrane after a dehydration process using the separation membrane, comprising: ２ O) and saturated water vapor pressure P ｓａｔ (H ２ O) and [P(H ２ O) / P ｓａｔ (H ２ 1. A method for shutting down a separation apparatus, comprising: placing a separation membrane in environment A, which satisfies the relationship [(Ratio of the temperature of the separation membrane to the temperature of the separator) / (Saturation of the temperature of the separator))≧0.001] and has a temperature of 100° C. or higher; and lowering the temperature of environment A.
2. The method for shutting down a separation apparatus according to claim 1, further comprising reducing the pressure of said environment A.
3. The method for shutting down a separation apparatus according to claim 2, further comprising reducing the pressure of the environment A and then lowering the temperature.
4. The method for shutting down a separation apparatus according to claim 3, wherein the temperature is lowered by adjusting the output of a temperature control means.
5. A method for shutting down a separation apparatus according to any one of claims 2 to 4, which includes maintaining the temperature of the environment A substantially constant during the decompression.
6. The method for shutting down a separation apparatus according to claim 5, wherein the pressure reduction operation is carried out in stages.
7. A method for shutting down a separation apparatus according to claim 1 or 2, which comprises maintaining the total pressure of the environment A substantially constant during the temperature drop.
8. The method for shutting down a separation apparatus according to claim 1 or 2, wherein the temperature of the environment A is less than 400°C.
9. In the environment A, the water vapor partial pressure P (H ２ O) and the saturated water vapor pressure P ｓａｔ (H ２ O) and [1>P(H ２ O) / P ｓａｔ (H ２ 3. The method for stopping a separation apparatus according to claim 1, wherein the following relationship is satisfied:
10. A method for shutting down a separation apparatus according to claim 2, wherein the pressure reduction operation is stopped when the total pressure of the environment A reaches atmospheric pressure + 10 kPa.
11. The method for shutting down a separation apparatus according to claim 1 or 2, wherein the separation membrane is a zeolite membrane.
12. The method for shutting down a separation apparatus according to claim 11, wherein the zeolite membrane is made of LTA-type zeolite.