Membrane separation system

Abstract

The present invention provides a membrane separation system capable of separating a condensed component in a liquid state in an energy-saving manner. A membrane separation system according to an embodiment of the present invention is provided with a membrane separator including a separation membrane. The membrane separator has a first flow path and a second flow path. The mixed gas is supplied to the first flow path. The mixed gas contains a permeable gas that can permeate through the separation membrane and a condensable component in a gaseous state. And a second flow path through which a permeate gas that has permeated through the separation membrane flows. The membrane separation system is configured such that a liquid-state condensable component is present at the downstream end of the first flow path in the direction in which the mixed gas passes.

Description

TECHNICAL FIELD

[0001] The present application relates to a membrane separation system. BACKGROUND

[0002] In a refrigeration cycle applied to an air conditioning device or the like, sometimes a non-condensable component such as air is mixed into a condensable component such as refrigerant vapor to produce a mixed gas. In this case, it is desirable to separate the non-condensable component from the mixed gas and recover the condensable component. For example, a non-condensable gas purge system is proposed which liquefies the condensable component by cooling the mixed gas to separate it from the non-condensable component (see, for example, Patent Literature 1). However, the non-condensable gas purge system described in Patent Literature 1 has a problem in that the mixed gas needs to be cooled to less than the condensation point, and the energy required for separation of the condensable component is large.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2019-515230 SUMMARY

[0006] The present application relates to a membrane separation system.

[0007] [1] The membrane separation system according to an embodiment of the present application includes a membrane separator including a separation membrane. The membrane separator has a first flow path and a second flow path. A mixed gas containing a permeation gas that can permeate through the separation membrane and a condensable component in a gaseous state is supplied to the first flow path. The permeation gas that has permeated through the separation membrane is allowed to flow through the second flow path. The membrane separation system is configured such that a condensable component in a liquid state is present at a downstream end portion of the first flow path in a passing direction of the mixed gas.

[0008] [2] In the membrane separation system according to the above [1], the first flow path can be inclined downward in a vertical direction as it tends toward a downstream side in the passing direction of the mixed gas.

[0009] [3] The membrane separation system according to the above [1] or [2] can be configured such that, when an upstream end portion of the first flow path in the passing direction is set to 0% and a downstream end portion is set to 100%, a condensable component in a liquid state is present in at least a portion of a range of 20% or more and 100% or less of the first flow path.

[0010] [4] The membrane separation system according to any one of the above [1] to [3] can be configured such that a condensable component in a liquid state is present on at least a portion of a surface of the first flow path.

[0011] [5] The membrane separation system according to any one of [1] to [4], wherein, when the start of stable operation in which the liquid-state condensable component is separated by supplying the mixed gas to the first flow path is set to 0% and the end is set to 100%, an average value of the gas permeation amount of the separation membrane during 90% to 100% of the stable operation can be 0.5 or more with respect to an average value of the gas permeation amount of the separation membrane during 45% to 55% of the stable operation.

[0012] [6] The membrane separation system according to any one of [1] to [5], wherein a protective layer can be provided on the surface of the separation membrane. The protective layer faces the first flow path.

[0013] [7] The membrane separation system according to any one of [1] to [6], wherein the separation membrane can be an inorganic membrane.

[0014] [8] The membrane separation system according to any one of [1] to [7] can further include a recovery unit. The recovery unit can recover the liquid-state condensable component.

[0015] [9] The membrane separation system according to any one of [1] to [8], wherein the membrane separator can further include a separation membrane container that houses the separation membrane. The separation membrane container can have a gas inlet, a first gas outlet, and a second gas outlet. The gas inlet communicates with an upstream end of the first flow path in the passing direction. The first gas outlet communicates with a downstream end of the first flow path in the passing direction. The second gas outlet communicates with the second flow path.

[0016] Effects of Invention

[0017] According to the embodiment of the present application, a membrane separation system that can separate a liquid-state condensable component in an energy-saving manner is provided. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a schematic configuration view of a membrane separation system according to an embodiment of the present application.

[0019] Figure 2 is a schematic configuration view of a membrane separation system according to another embodiment of the present application.

[0020] Figure 3 is a schematic configuration view for explaining the configuration of a separation membrane of Figure 1

[0021] Figure 4 is a schematic configuration view of a membrane separation system according to still another embodiment of the present application. ​

[0022] Figure 5 is a schematic configuration view of a separation membrane composite body having Figure 1

[0023] Figure 6 is a schematic cross-sectional view of a separation membrane composite body having Figure 5

[0024] Figure 7 is a schematic perspective view of a modification example of a separation membrane composite body.

[0025] Figure 8 is a schematic cross-sectional view of a separation membrane composite body having Figure 7 DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present application will be described with reference to the drawings, but the present application is not limited to these embodiments. Also, in order to make the description more clear, the drawings sometimes schematically show the width, thickness, shape, and the like of each portion as compared with the embodiments, but this is only an example and does not limit the explanation of the present application.

[0027] A. Schematic of a membrane separation system

[0028] Figure 1 is a schematic configuration view of a membrane separation system according to an embodiment of the present application.

[0029] The membrane separation system 100 of the illustrated example has a membrane separator 1 including a separation membrane 11. The membrane separator 1 has a first flow path A and a second flow path B. In the first flow path A, a mixed gas containing a permeation gas and a condensed component in a gaseous state that can permeate through the separation membrane 11 is supplied. In the second flow path B, a permeation gas that has permeated through the separation membrane 11 is caused to flow. The membrane separation system 100 is configured so that the condensed component in a liquid state exists at a downstream end portion of the first flow path A in a passing direction of the mixed gas.

[0030] According to such a configuration, when the mixed gas containing the permeation gas and the condensed component in the gaseous state is supplied to the first flow path, at least a part of the permeation gas contained in the mixed gas is caused to permeate through the separation membrane and flow into the second flow path. Therefore, the partial pressure of the condensed component in the mixed gas that has passed through the first flow path rises as it tends toward the downstream side in the passing direction. As a result, the condensed component can be smoothly liquefied and exist at the downstream end portion of the first flow path in the passing direction. According to this, in such a membrane separation system, the configuration is simple, and the condensed component in the liquid state can be separated and recovered in an energy-saving manner.

[0031] As the permeation gas contained in the mixed gas, for example, air can be given.

[0032] ​​​The condensable component contained in the mixed gas preferably contains a refrigerant. As the refrigerant, for example, glycols, fluorine-containing compounds can be given. The condensable component can be used alone or in combination. Among the condensable components, glycols are preferable.

[0033] The separation membrane 11 has a cylindrical shape extending in the passing direction of the mixed gas. The separation membrane 11 having the cylindrical shape includes the first flow path A in the inside thereof. The length of the first flow path A can be arbitrarily and appropriately adjusted.

[0034] Note that although not shown, the outside of the separation membrane 11 having the cylindrical shape can be in contact with the first flow path A. In this case, the inside of the separation membrane 11 can constitute the second flow path B.

[0035] In the illustrated example, the membrane separator 1 is provided with one separation membrane 11. As shown in Figure 2 , the membrane separator 1 can be provided with a plurality of separation membranes 11. In the illustrated example, the plurality of separation membranes 11 are connected in series in a manner that the internal spaces of the separation membranes 11 communicate with each other. In this case, the separation membranes 11 adjacent to each other among the plurality of separation membranes 11 can be connected by the connection line 16.

[0036] In the membrane separator 1 provided with the plurality of separation membranes 11, the internal spaces of the plurality of separation membranes 11 and the internal space of the connection line 16 provided as needed constitute the first flow path A.

[0037] Note that hereinafter, for convenience, the first flow path A will be described with reference to the membrane separator 1 provided with one separation membrane 11 shown in Figure 1 , Figure 3 and Figure 4 , but the first flow path A of the membrane separator 1 provided with the plurality of separation membranes 11 can also be described similarly.

[0038] As shown in Figure 1 , in one embodiment, the membrane separation system 100 is configured such that the condensable component in the liquid state exists on at least a part of the surface of the first flow path A. According to such a configuration, the condensable component in the liquid state can be smoothly discharged from the first flow path along the surface. Therefore, it is possible to suppress excessive accumulation of the condensable component in the liquid state in the first flow path.

[0039] In one embodiment, the membrane separation system 100 is configured such that, when the upstream end of a first flow path A in the flow direction is set to 0% and the downstream end to 100%, at least a portion of the first flow path A in a range of 20% to 100% contains a liquid-state condensable component. In the range of 20% to 100% of the first flow path A, in addition to the liquid-state condensable component, a gaseous-state condensable component may also be present. On the other hand, in the range of 0% to 20% of the first flow path A, a gaseous-state condensable component is present, but typically no liquid-state condensable component is present. With this configuration, in the range of 0% to 20% of the first flow path where the partial pressure of the permeate gas in the mixed gas is relatively high, the separation membrane efficiently allows the permeate gas to pass through, and in the range of 20% to 100% of the first flow path A where the partial pressure of the condensable component in the mixed gas is relatively high, the condensable component can be stably liquefied.

[0040] In one embodiment, the membrane separation system 100 further includes a recovery unit 7. The recovery unit 7 is capable of recovering condensable components in a liquid state. The recovery unit 7 can have any suitable configuration. Typically, the recovery unit 7 is capable of recovering condensable components in a liquid state discharged from the downstream end of the first flow path A. It should be noted that the presence or absence of condensable components in a liquid state at the downstream end of the first flow path A can be determined based on the presence or absence of condensable components in a liquid state recovered by the recovery unit.

[0041] like Figure 3 As shown, the first flow path A can be inclined downward in the vertical direction along the downstream side of the direction in which the mixed gas passes. In one embodiment, at least a portion of the separation membrane 11 is configured such that the downstream end of the first flow path A is located vertically downward than the upstream end. In the example shown, the separation membrane 11 is configured such that the entire membrane 11 is inclined relative to the horizontal direction. If the first flow path is inclined in this way, the accumulation of condensable components in the liquid state can be stably suppressed within the first flow path. In particular, when the membrane separation system has a recovery section, the condensable components in the liquid state can be smoothly discharged toward the recovery section.

[0042] The angle θ between the direction in which the first flow path extends and the horizontal direction can be arbitrarily and appropriately adjusted based on the orientation of the gas flow, the surface tension, the diameter of the first flow path, and the like. The angle θ between the direction in which the first flow path extends and the horizontal direction is, for example, more than 0° and 90° or less. If the angle θ between the direction in which the first flow path extends and the horizontal direction is steep, the discharge speed of the condensable component in the liquid state can be increased. On the other hand, if the angle θ between the direction in which the first flow path extends and the horizontal direction is gentle, the condensable component in the liquid state can be accumulated in the lower portion of the first flow path, and thus the condensable component in the liquid state present in the upper portion of the first flow path can be reduced. That is, if the angle θ between the direction in which the first flow path extends and the horizontal direction is gentle, the coverage ratio of the first flow path can be reduced. Therefore, it is preferable to appropriately adjust the angle θ between the direction in which the first flow path extends and the horizontal direction to balance the increase in the discharge speed of the condensable component in the liquid state and the low coverage ratio of the first flow path.

[0043] The lower limit value of the above-described angle θ is preferably the sliding angle of the generated condensable component in the liquid state. According to this, the condensable component in the liquid state can be efficiently discharged.

[0044] The sliding angle of the generated condensable component in the liquid state can be solved experimentally using, for example, a tilting method. In the case of solving the sliding angle experimentally, a sample obtained by cutting and separating the membrane can be used on the solid side, and a sample such as a flat plate prepared in substantially the same manner as the actual separation membrane at the time of measuring the tilting angle can be used. In addition, a simulated liquid prepared in accordance with the properties of the condensable component can be used on the liquid side. Typically, 10 mg of the simulated liquid can be used. The apparatus used in the calculation of the sliding angle of the condensable component in the liquid state using the tilting method is not particularly limited, and, for example, B100W manufactured by Asumi Engineering Co., Ltd. or an extension device based on this can be used.

[0045] In addition, the sliding angle of the generated condensable component in the liquid state can also be estimated using a known adhesion energy.

[0046] The sliding angle can vary depending on the gas flow of the gas flowing through the first flow path. Specifically, since the condensable component in the liquid state is pressed by the gas flow, if the flow rate of the gas becomes large, the sliding angle can become small. In this case, the influence due to the gas flow rate is appropriately corrected with respect to the sliding angle solved experimentally using, for example, the tilting method, and the actual sliding angle can be estimated.

[0047] The upper limit value of the above-described angle θ is preferably 80°. The coverage ratio of the first flow path can be estimated by the following formula.

[0048] Coverage ratio = 1 - 0.5 x cos(θ)

[0049] That is, since the condensed component in a liquid state is able to be accumulated in the lower portion of the first flow path when the angle θ is 0° as described above, the coverage rate is 0.5. In addition, since there is no difference between the upper portion and the lower portion of the first flow path when the angle θ is 90°, the coverage rate is 1. At this time, it is generally known that the permeation performance of the separation membrane of the covered portion is significantly reduced due to the reduction of the effective membrane area or the like, and for example, it can be reduced to about 1 / 10 as compared with the performance of the non-covered portion. Based on the above insight, the relationship between the above angle θ and the degree of reduction of the permeation performance of the separation membrane is calculated, and it is found that if the above angle θ is greater than 80°, the permeation performance of the separation membrane is significantly reduced. Therefore, by making the above angle θ be 80° or less, it is possible to reduce the coverage rate to the first flow path, and effectively exhibit the permeation performance of the separation membrane.

[0050] In addition, in the case where the membrane separation system is provided with the recovery portion, it is possible to temporarily increase the flow rate of the mixed gas supplied to the first flow path A of the separation membrane system 100. Thereby, it is possible to discharge the condensed component in a liquid state from the membrane separation system into the first flow path. In particular, in the case where the condensed component in a liquid state is accumulated, and in the case where the condensed component in a liquid state is highly viscous, it is possible to smoothly discharge the condensed component in a liquid state toward the recovery portion, and thus it is preferable.

[0051] As shown in FIG. 1, one embodiment includes a membrane separator 1. The membrane separator 1 includes a separation membrane 11. The separation membrane 11 is provided with a first flow path A and a second flow path B. The first flow path A is a flow path through which a mixed gas containing a permeated gas and a condensed component in a gaseous state passes. The second flow path B is a flow path through which the permeated gas passes. Figure 1 As shown in FIG. 1, one embodiment includes a membrane separator 1. The membrane separator 1 includes a separation membrane 11. The separation membrane 11 is provided with a first flow path A and a second flow path B. The first flow path A is a flow path through which a mixed gas containing a permeated gas and a condensed component in a gaseous state passes. The second flow path B is a flow path through which the permeated gas passes.

[0052] The second gas outlet 23 communicates with the second flow path B. The second gas outlet 23 is able to discharge the permeated gas from the second flow path B in the stable operation described later.

[0053] In one embodiment, the membrane separation system 100 is further provided with a supply portion 6. The supply portion 6 is able to supply the mixed gas containing the permeated gas and the condensed component in a gaseous state to the first flow path A of the membrane separator 1. In the illustrated example, the supply portion 6 is provided with a supply line 61.

[0054] Supply line 61 is a piping for supplying mixed gas to the first flow path A. Although not shown, the upstream end of the mixed gas in the supply line 61 in the supply direction is connected to a storage tank, for example, for storing the mixed gas. Typically, the downstream end of the mixed gas in the supply line 61 in the supply direction is connected to the separation membrane container 2 in communication with the gas inlet 21.

[0055] The membrane separation system 100 may further incorporate any suitable configuration without impairing the effects of the present invention. Examples of such configurations include those capable of adjusting the temperature and / or pressure of the mixed gas in the first flow path (e.g., a cooling mechanism, a compression mechanism).

[0056] like Figure 4 As shown, in one embodiment, the supply unit 6 further includes a booster compressor 62. The booster compressor 62 is installed on the supply line 61 and can adjust the pressure of the mixed gas passing through the supply line 61. This allows for smooth adjustment of the temperature and / or pressure of the mixed gas in the first flow path.

[0057] The following is a detailed description of the separation membrane.

[0058] B. Separation membrane

[0059] The separation membrane 11 is configured such that the aforementioned permeable gas passes through relatively easily, while the aforementioned condensable components in the gaseous state pass through less easily than the aforementioned permeable gas. In other words, the permeation rate of the condensable components in the gaseous state through the separation membrane is sufficiently small compared to the permeation rate of the permeable gas. Therefore, the partial pressure of the condensable components in the mixed gas passing through the first flow path increases as it tends towards the downstream side in the flow direction.

[0060] When the start of stable operation (described later) is set to 0% and the end to 100%, the average gas permeation rate of the separation membrane 11 during the 90% to 100% period of stable operation (hereinafter referred to as the final average gas permeation rate) is, for example, 0.5 or more, preferably 0.7 or more, and more preferably 0.9 or more, relative to the average gas permeation rate of the separation membrane 11 during the 45% to 55% period of stable operation (hereinafter referred to as the intermediate average gas permeation rate). On the other hand, the upper limit of the final average gas permeation rate relative to the intermediate average gas permeation rate is typically 1.0. That is, the separation membrane is configured such that the final average gas permeation rate is in this range. Therefore, even if condensable components in a liquid state are generated, the separation membrane can ensure sufficient gas permeation rate.

[0061] As such a separation membrane 11, for example, an organic membrane, an inorganic membrane can be cited, and preferably an inorganic membrane can be cited. In the case where the separation membrane is constituted by an organic membrane, as its structure, for example, a hollow fiber structure, a spiral structure can be cited. In contrast to this, if the separation membrane is constituted by an inorganic membrane, since the rigidity of the inorganic membrane is more excellent than that of the organic membrane, it is possible to design the diameter of the first flow path to be larger. As a result, compared to the case where the separation membrane is constituted by an organic membrane, even if the fluid flowing in the first flow path is a gas-liquid mixed phase, it is possible to significantly reduce the pressure loss in the first flow path.

[0062] The thickness of the separation membrane 11 can be arbitrarily and appropriately adjusted.

[0063] As shown in FIG. 1, in one embodiment, the separation membrane 11 is supported on the base material 12. In other words, the membrane separator 1 further has the base material 12. The separation membrane 11 and the base material 12 constitute a separation membrane composite 10. Figure 5 The base material 12 can adopt an arbitrary and appropriate shape. As the shape of the base material 12, for example, a cylindrical shape, a honeycomb shape, a flat plate shape can be cited.

[0064] In one embodiment, the base material 12 is a porous base material. The porous base material, for example, has a monolithic structure which has a three-dimensionally networked continuous skeleton and a communication hole defined by the skeleton.

[0065] The porous base material can be constituted by an arbitrary and appropriate material. As the material of the porous base material, typically, a ceramic sintered body can be cited. As the ceramic sintered body, for example, alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, cordierite can be cited. The ceramic sintered body can be used alone or in combination. Among the ceramic sintered bodies, preferably, alumina can be cited.

[0066] The porous base material can contain an inorganic bonding material. As the inorganic bonding material, for example, titania, mullite, sinterability-improved alumina, silica, glass frit, clay mineral, sinterability-improved cordierite can be cited. The inorganic bonding material can be used alone or in combination.

[0067] The porous base material can be constituted by a single layer, or can have a multilayer structure in which a plurality of layers are stacked. In one embodiment, the porous base material has a multilayer structure which has a plurality of layers having different pore diameters from each other, as shown in FIG. 2.

[0068] Figure 6 In this case, it is preferable that the closer to the separation membrane 11, the smaller the pore diameter.

[0069] ​The average pore diameter of the porous base material is, for example, 0.01 μm to 70 μm, preferably 0.05 μm to 25 μm. The average pore diameter of the porous base material on the separation membrane side is 0.01 μm to 1 μm, preferably 0.05 μm to 0.5 μm. As for the distribution of the pore diameter of the entire porous base material 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 base material on the separation membrane side is, for example, 25% to 50%. The average pore diameter of the porous base material can be measured using, for example, a mercury porosimeter, a pore size distribution measuring device, or a nano-size pore size distribution measuring device.

[0070] In one embodiment, the base material 12 is a cylindrical base material 12a. As a cross-sectional shape of the cylindrical base material 12a in a direction orthogonal to the length direction, for example, a triangle, a quadrangle, a pentagon, a hexagon or more, a circle, or an ellipse can be given, and preferably a circle can be given. The outer diameter and the length of the cylindrical base material can be appropriately set according to the purpose.

[0071] In the illustrated example, the separation membrane 11 is formed on the inner surface of the cylindrical base material 12a. The separation membrane 11 can be formed on the entire inner surface of the cylindrical base material 12a as in the illustrated example, or can be formed on a part of the cylindrical base material 12a. The inner space of the cylindrical base material 12a (a space defined by the inner peripheral surface of the cylindrical base material) includes the first flow path A, and the outer peripheral surface of the cylindrical base material 12a and the inner surface of the separation membrane container 2 (refer to Figure 1 ) define the second flow path B.

[0072] In another embodiment, as shown in Figure 7 and Figure 8 , the base material 12 is a honeycomb-shaped base material 12b. The honeycomb-shaped base material 12b has partition walls 123 that define a plurality of cells 124. The cells 124 are formed in a cylindrical shape so as to pass through the honeycomb-shaped base material 12b in the length direction.

[0073] The cells 124 extend from the first end surface El (inflow end surface) to the second end surface E2 (outflow end surface) of the honeycomb-shaped base material 12b in the length direction (axial direction) of the honeycomb-shaped base material 12b (refer to Figure 8 ). The cells 124 have an arbitrary appropriate shape in the cross section in a direction orthogonal to the length direction of the honeycomb-shaped base material 12b. As the cross-sectional shape of the cells, for example, a triangle, a quadrangle, a pentagon, a hexagon or more, a circle, or an ellipse can be given. The cross-sectional shape and the size of the cells can be the same throughout, or can be different at least in part. Among such cross-sectional shapes of the cells, preferably a circle can be given.

[0074] The distance between the center axes of the plurality of cells 124 is, for example, 0.3 mm to 20 mm. The cell density (i.e., the number of cells 124 per unit area) in a cross section of the honeycomb-shaped substrate in a direction orthogonal to the length direction can be appropriately set according to the purpose. The cell density can be, for example, 0.5 cells / cm 2 to 320 cells / cm 2 If the cell density is in such a range, the strength of the honeycomb-shaped substrate and the effective GSA (geometric surface area) can be sufficiently ensured.

[0075] The honeycomb-shaped substrate 12b has an arbitrary appropriate shape (overall shape). As the shape of the honeycomb-shaped substrate, for example, a cylindrical shape with a circular bottom surface, an elliptical cylindrical shape with an elliptical bottom surface, a prismatic shape with a polygonal bottom surface, or a columnar shape with an irregular bottom surface can be given. The honeycomb-shaped substrate 12b of the illustrated example has a cylindrical shape. The outer diameter and the length of the honeycomb-shaped substrate can be appropriately set according to the purpose.

[0076] In the illustrated example, the separation membrane 11 is formed on the inner surface of each of the plurality of cells 124. The separation membrane 11 can be formed on the entire inner surface of the cell 124, or can be formed on a part of the inner surface of the cell 124. The internal space of each of the plurality of cells 124 (the space defined by the inner peripheral surface of the cell) includes the first flow path A, and the outer peripheral surface of the honeycomb-shaped substrate 12b and the inner surface of the separation membrane container 2 (see FIG. 1) define the second flow path B. Figure 1

[0077] In one embodiment, a protective layer 13 is provided on the surface of the separation membrane 11. In the illustrated example, the protective layer 13 is located on the side opposite to the substrate 12 with respect to the separation membrane 11, and faces the first flow path A. According to such a configuration, it is possible to suppress the direct contact of the condensed component in the liquid state with the separation membrane. Therefore, compared to the case where the separation membrane faces the first flow path, it is possible to sufficiently ensure the performance of the separation membrane in stable operation. As a result, it is possible to stably achieve the average value of the gas permeation amount (the final period average gas permeation amount, the intermediate period average gas permeation amount) described above in stable operation.

[0078] As the material of the protective layer 13, for example, a material in which the mixing with the condensed component in the liquid state is suppressed can be given. Typically, the material of the protective layer 13 can be selected based on the solubility parameter. The material of the protective layer 13 can be in a liquid state or in a solid state at normal temperature (23°C) and normal pressure (0.1 MPaA (absolute pressure)). From the viewpoint of the durability of the membrane separator, the material of the protective layer is preferably a solid. On the other hand, if the material of the protective layer is a liquid, the protective layer can be additionally formed on the separation membrane.

[0079] ​The protective layer 13 can be provided on the entire surface of the separation membrane 11, or on a part of the surface of the separation membrane 11. For example, the protective layer 13 can be provided only on a portion where the condensed component in a liquid state can exist. The thickness of the protective layer 13 can be arbitrarily and appropriately adjusted.

[0080] C. Details of the operation method of the membrane separation system (method for recovering condensed component in a liquid state)

[0081] Next, the operation method of the membrane separation system will be described.

[0082] In the operation method of the membrane separation system 100, in stable operation, the mixed gas described above is supplied to the first flow path A, and the condensed component in a liquid state is separated and recovered. In more detail, regarding the stable operation of the membrane separation system 100, various conditions are arbitrarily and appropriately adjusted so that the condensed component in a liquid state exists in the first flow path A as described above, and the stable operation is performed. Note that the start time and the end time of the stable operation can each be arbitrarily and appropriately set. For example, the start time of the supply of the mixed gas to the first flow path A can be set as the start time of the stable operation, and the end time of the supply of the mixed gas to the first flow path A can be set as the end time of the stable operation.

[0083] As the conditions that can be adjusted in the stable operation, for example, the temperature and / or the pressure of the mixed gas supplied to the first flow path, the pressure in the second flow path, and the flow rate of the mixed gas can be given.

[0084] Thus, in the membrane separation system 100, the permeated gas is separated from the mixed gas, typically at the gas permeation amount described above, and the condensed component in a liquid state is separated and recovered in an energy-saving manner.

[0085] Industrial applicability

[0086] The membrane separation system according to the embodiment of the present application is used for separating a condensed component from a mixed gas, and can be particularly preferably used for separating a refrigerant from a mixed gas.

[0087] Explanation of symbols

[0088] 1 Membrane separator

[0089] 11 Separation membrane

[0090] 12 Base material

[0091] 13 Protective layer

[0092] 2 Separation membrane container

[0093] 21 Gas inlet

[0094] 22 First gas outlet

[0095] 23 second gas outlet

[0096] A first flow path

[0097] B second flow path

Claims

1. A membrane separation system comprising a membrane separator including a separation membrane, The membrane separator has the following features: A first flow path is supplied with a mixed gas comprising a permeate gas capable of passing through the separation membrane and a condensable component in a gaseous state; and A second flow path is provided for the permeate gas that has passed through the separation membrane. The membrane separation system is configured such that, at the downstream end of the first flow path in the direction of passage of the mixed gas, the condensable component is present in a liquid state.

2. The membrane separation system according to claim 1, wherein, The first flow path tilts downward in the vertical direction as it moves downstream in the direction of the flow of the mixed gas.

3. The membrane separation system according to claim 1, wherein, The membrane separation system is configured such that, when the upstream end of the first flow path in the passing direction is set to 0% and the downstream end is set to 100%, at least a portion of the first flow path in a range of 20% to 100% contains the condensable component in a liquid state.

4. The membrane separation system according to claim 3, wherein, The membrane separation system is configured such that at least a portion of the condensable component in a liquid state is present on the surface defining the first flow path.

5. The membrane separation system according to any one of claims 1 to 4, wherein, When the start of stable operation, in which the mixed gas is supplied to the first flow path to separate the liquid condensable component, is set to 0% and the end is set to 100%, the average gas permeation rate of the separation membrane during the 90% to 100% period of stable operation is 0.5 or more relative to the average gas permeation rate of the separation membrane during the 45% to 55% period of stable operation.

6. The membrane separation system according to claim 5, wherein, A protective layer is provided on the surface of the separation membrane, and the protective layer faces the first flow path.

7. The membrane separation system according to claim 5, wherein, The separation membrane is an inorganic membrane.

8. The membrane separation system according to any one of claims 1 to 4, wherein, It also includes a recovery unit capable of recovering the condensable components in liquid form.

9. The membrane separation system according to any one of claims 1 to 4, wherein, The membrane separator also includes a membrane container for housing the membrane. The separation membrane container has: A gas inlet, which communicates with the upstream end of the first flow path in the passing direction; A first gas outlet, which communicates with the downstream end of the first flow path in the passing direction; and A second gas outlet, which is connected to the second flow path.

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