Gas separation membrane unit and gas separation device

Abstract

To provide a gas separation membrane unit which can maintain a high concentration of a predetermined gas component on a surface of a gas separation membrane and inhibit deterioration of separation efficiency, and to provide a gas separation device.SOLUTION: A gas separation membrane unit includes: a gas separation membrane configured to separate a predetermined gas component contained in a mixed gas supplied to a first surface by causing the predetermined gas component to permeate to a second surface that is a reverse surface of the first surface; a gas flow path part having a wall body defining an internal space through which the predetermined gas component separated flows; and a first convex structure protruding from at least one of the first surface of the gas separation membrane and an outer surface of the wall body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas separation membrane unit and a gas separation device. [Background technology]

[0002] To achieve carbon neutral or carbon negative, technologies are being considered for capturing and capturing carbon dioxide emitted from thermal power plants, boiler facilities, etc., and carbon dioxide in the atmosphere. One known technology for this purpose is the membrane separation method, which separates carbon dioxide using a gas separation membrane.

[0003] For example, Patent Document 1 discloses a gas separation method for selectively permeating a specific gas (A) from a mixed gas using a gas separation membrane. This gas separation method includes supplying the mixed gas to one side of a gas separation membrane, in which the membrane thickness of the gas separation membrane is 1 μm or less, the concentration of the gas (A) in the mixed gas is 10,000 mass ppm or less, and the selective permeation of the gas (A) by the gas separation membrane is performed under conditions where the pressure difference across both sides of the gas separation membrane is 1 atmosphere or less.

[0004] According to this gas separation method, the gas (A) can be separated satisfactorily even under mild conditions such as a pressure difference of 1 atmosphere or less across the two sides of the gas separation membrane. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-033590 A Summary of the Invention [Problem to be solved by the invention]

[0006] In membrane separation, the challenge is to increase the separation efficiency of a specific gas component. In order to increase the separation efficiency of a gas separation membrane, it is necessary to maintain a high concentration of the specific gas component on the upstream side of the gas separation membrane. However, when the specific gas component permeates the gas separation membrane, the concentration on the upstream side decreases accordingly, resulting in a decrease in separation efficiency.

[0007] Therefore, there is a demand for a gas separation device that is less likely to lose concentration even when a specific gas component permeates a gas separation membrane, and that can suppress a decrease in separation efficiency. [Means for solving the problem]

[0008] The gas separation membrane unit according to the application example of the present invention is a gas separation membrane that separates a predetermined gas component contained in a mixed gas supplied to a first surface by transmitting the predetermined gas component to a second surface that is the reverse side of the first surface; a gas flow path portion having a wall defining an internal space through which the separated predetermined gas component flows; a first convex structure protruding from at least one of the first surface of the gas separation membrane and an outer surface of the wall; has.

[0009] A gas separation device according to an application example of the present invention includes: A gas separation membrane unit according to an application example of the present invention; an exhaust pump that exhausts the predetermined gas component flowing through the internal space of the gas flow path portion; Equipped with. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a configuration of a gas separation device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the gas separation device shown in FIG. [Diagram 3] FIG. 3 is a schematic diagram in which an example of a gas flow is added to a part of the cross-sectional view shown in FIG. 2. [Figure 4]FIG. 13 is a schematic diagram in which an example of a gas flow is added to a cross-sectional view of a model (conventional model) in which a first convex structure is omitted. [Diagram 5] 2 is a partially enlarged view showing a first convex structure of FIG. 1. [Figure 6] 4 is a graph showing the relationship between the gas permeability of a gas separation membrane to carbon dioxide and the concentration of carbon dioxide on a first surface of the gas separation membrane. [Figure 7] 1 is a graph showing the relationship between the flow rate of a mixed gas and the concentration rate of carbon dioxide in a gas separation membrane. [Figure 8] FIG. 4 is a cross-sectional view showing the configuration of a gas separation device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a gas separation membrane unit and a gas separation device of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

[0012] 1. First embodiment First, a gas separation membrane unit and a gas separation device according to a first embodiment will be described.

[0013] Fig. 1 is a perspective view showing the configuration of a gas separation device 1 according to the first embodiment. Fig. 2 is a cross-sectional view of the gas separation device 1 shown in Fig. 1.

[0014] In each figure of the present application, the X-axis, Y-axis, and Z-axis are set as three mutually orthogonal axes. Each axis is represented by an arrow, with the tip of the arrow being "plus" and the base of the arrow being "minus". In the following description, for example, "X-axis direction" includes both the plus and minus directions of the X-axis. The same applies to the Y-axis and Z-axis directions. In the following description, the plus side of the Z-axis is also referred to as "upper" and the minus side of the Z-axis is also referred to as "lower". However, the Z-axis does not need to be parallel to the vertical axis, and may cross the vertical axis.

[0015] 1.1. Overview The gas separation device 1 shown in FIG. 1 includes two gas separation membrane units 2, 2 (gas separation membrane units according to the embodiment) and an exhaust pump 6. The gas separation membrane unit 2 includes a gas separation membrane 3, a gas flow path section 4, and a first convex structure 5. The gas separation membrane 3 separates carbon dioxide CO2 (a predetermined gas component) contained in the mixed gas G1 supplied to the first surface 31 (front surface) by allowing it to permeate to the second surface 32 (rear surface) preferentially over other gas components. The gas flow path section 4 includes a wall 41 that defines an internal space S1 through which a gas containing carbon dioxide CO2 that has been preferentially separated and extracted (a gas having a higher concentration of carbon dioxide CO2 than the mixed gas G1) flows. The first convex structure 5 protrudes from the first surface 31 of the gas separation membrane 3 and an outer surface 412 of the wall 41. The wall 41 holds the gas separation membrane 3, and the outer surface 412 of the wall 41 on which the first convex structure 5 is provided is disposed on the outer periphery of the gas separation membrane 3.

[0016] In such a gas separation membrane unit 2, the first convex structures 5 generate turbulence under predetermined conditions in the airflow formed on the first surface 31 of the gas separation membrane 3. As a result, even if carbon dioxide CO2 in the mixed gas G1 on the first surface 31 permeates through the gas separation membrane 3 and the concentration decreases, new mixed gas G1 is efficiently replenished onto the first surface 31. As a result, the concentration of carbon dioxide CO2 on the first surface 31 can be maintained high, and a decrease in the separation efficiency of the gas separation membrane 3 can be suppressed.

[0017] 1.2.Gas separation membrane unit 1, two gas separation membrane units 2, 2 are arranged side by side and spaced apart from each other in the Z-axis direction. By providing the gas separation device 1 with multiple gas separation membrane units 2, 2, it is possible to realize a gas separation device 1 with high separation efficiency of carbon dioxide CO2.

[0018] The direction in which the two gas separation membrane units 2, 2 are arranged may be any direction intersecting with the first surface 31, and is not limited to the Z-axis direction (direction intersecting with the first surface 31); however, if they are arranged in the Z-axis direction, the footprint of the gas separation device 1 can be reduced.

[0019] The exhaust pump 6 is connected to the gas flow path section 4 and exhausts the internal space S1 containing carbon dioxide CO2. This reduces the pressure in the internal space S1 below atmospheric pressure, generating a pressure difference between the first surface 31 side and the second surface 32 side of the gas separation membrane 3. The gas separation membrane 3 can separate carbon dioxide CO2 by permeating it using this pressure difference as a driving force.

[0020] The gas separation membrane unit 2 is placed in an environment in which a mixed gas G1 is present. The mixed gas G1 contains carbon dioxide CO2, which is the gas component to be separated, and other gas components (non-target components). The mixed gas G1 is not particularly limited, but may be, for example, the atmosphere or exhaust gas discharged from facilities such as factories. The gas component to be separated is not limited to carbon dioxide CO2, and may be other gas components. The non-target components vary depending on the mixed gas G1, but when the mixed gas G1 is the atmosphere, they are nitrogen, oxygen, etc.

[0021] The gas separation membrane unit 2 is exposed to the airflow of the mixed gas G1. In each figure of the present application, the direction of the airflow of the mixed gas G1 is indicated by an arrow. In this embodiment, the airflow of the mixed gas G1 is formed from the negative side of the Y axis toward the positive side of the Y axis. By being exposed to the airflow, the mixed gas G1 having a high concentration of carbon dioxide CO2 is continuously supplied. This allows the separation efficiency of carbon dioxide CO2 in the gas separation membrane unit 2 to be maintained at a high level. In this specification, the negative side of the Y axis is referred to as the "upstream" and the positive side of the Y axis is referred to as the "downstream" of the airflow of the mixed gas G1.

[0022] When the mixed gas G1 is the atmosphere, the airflow of the mixed gas G1 may be a natural airflow or a flow generated by a fan (not shown). When the mixed gas G1 is exhaust gas, the airflow of the mixed gas G1 may be a flow generated by the exhaust source or a flow generated by a fan (not shown). Therefore, the gas separation device 1 may be provided with a fan that generates an airflow in the mixed gas G1.

[0023] The distance d between the gas separation membrane units 2 in the Z-axis direction is set longer than the protruding height of the first convex structures 5, for example, about 1 mm or more and 1 m or less, and preferably 10 mm or more and 10 cm or less.

[0024] The number of gas separation membrane units 2 included in the gas separation device 1 is not limited to two, and may be one, or three or more.

[0025] 1.2.1. Gas separation membranes The gas separation membrane 3 has a first surface 31 and a second surface 32 which are opposite surfaces. The gas separation membrane 3 selectively allows carbon dioxide CO2 contained in the mixed gas G1 supplied to the first surface 31 side to permeate to the second surface 32 side preferentially over other gas components. Therefore, the gas separation membrane 3 has a property that the gas permeability of carbon dioxide CO2 is greater than the gas permeability of non-target components (a property that the gas selectivity ratio of carbon dioxide CO2 is high). Hereinafter, the ratio of the gas permeability of carbon dioxide to the gas permeability of nitrogen will be simply referred to as the "gas selectivity ratio."

[0026] The gas selection ratio of the gas separation membrane 3 is preferably 3 or more, and more preferably 10 or more and 1000 or less. When the gas selection ratio is within the above range, the gas separation membrane 3 can efficiently separate and recover carbon dioxide CO2 in the mixed gas G1.

[0027] The nitrogen gas permeability of the gas separation membrane 3 and the carbon dioxide gas permeability of the gas separation membrane 3 are each measured in accordance with the gas permeability test method (Part 1: differential pressure method) specified in JIS K 7126-1:2006. A gas permeability measuring device is used for the measurement. An example of the gas permeability measuring device is GTR-11A / 31A manufactured by GTR Tech Co., Ltd. In this device, the gas that has permeated the gas separation membrane 3 is introduced into a gas chromatograph, and the gas permeability of each component is measured.

[0028] In the gas separation membrane 3, the gas permeability of carbon dioxide is preferably 1000 GPU or more, more preferably 5000 GPU or more and 100,000 GPU or less, and even more preferably 10,000 GPU or more and 50,000 GPU or less. This makes it possible to realize a gas separation membrane 3 that can reduce the amount of energy input required for separation, specifically, reduce the pressure difference between the first surface 31 side and the second surface 32 side. If the gas permeability of carbon dioxide of the gas separation membrane 3 falls below the lower limit, a lot of energy is required to separate carbon dioxide, and there is a risk of reducing the economic efficiency of the operation of the gas separation device 1. On the other hand, if the gas permeability of carbon dioxide of the gas separation membrane 3 exceeds the upper limit, there is a risk of increasing the cost of manufacturing (procuring) the gas separation membrane 3. 1 GPU is 3.35×10 -10 mol m -2 ·s -1 ·Pa -1 It is.

[0029] The thickness of the gas separation membrane 3 is not particularly limited, but is preferably 1 nm to 1000 μm, more preferably 5 nm to 100 μm, and even more preferably 10 nm to 10 μm.

[0030] The average thickness of the gas separation membrane 3 is the average value of thicknesses measured at 10 points on the gas separation membrane 3. The thickness of the gas separation membrane 3 can be measured using, for example, a thickness gauge.

[0031] The size of the gas separation membrane 3 is not particularly limited, but the maximum length is preferably 5 cm to 2 m, and more preferably 10 cm to 1 m, which provides a gas separation membrane 3 that has mechanical strength sufficient to withstand pressure differences and ensures a sufficient gas permeability.

[0032] The gas separation membrane 3 may be a single layer or a composite layer formed by laminating multiple layers. The gas separation membrane 3 may also be supported by a porous layer that is porous. In particular, when the thickness of the gas separation membrane 3 is 100 μm or less, it is preferable to laminate the gas separation membrane 3 and a porous layer to improve the overall strength.

[0033] Examples of materials constituting the gas separation membrane 3 include polymeric materials, ceramic materials, and metal materials. The materials constituting the gas separation membrane 3 may also be composite materials of these materials or composite materials of these materials and other materials.

[0034] Examples of polymeric materials include polyolefin resins such as polyethylene and polypropylene, fluorine-containing resins such as polytetrafluoroethylene, polyvinyl fluoride and polyvinylidene fluoride, organopolysiloxane (silicone resin), polystyrene, cellulose, cellulose acetate, polyurethane, polyacrylonitrile, polyphenylene oxide, polysulfone, polyethersulfone, polyimide, polyaramid, nylon, and the like.

[0035] Examples of the ceramic material include alumina, cordierite, mullite, silicon carbide, zirconia, etc. Examples of the metal material include stainless steel, etc.

[0036] 1.2.2.Gas flow path The gas flow path section 4 has a wall body 41 that defines an internal space S1 through which the separated gas containing carbon dioxide CO2 flows, and an exhaust port 42 provided in the wall body 41.

[0037] The wall 41 is a box having a flat shape extending along the XY plane, a hollow interior, and a substantially rectangular parallelepiped shape. The wall 41 defines the internal space S1 described above. In addition, a part of each of the two faces intersecting with the Z axis is opened, and the gas separation membrane 3 is arranged so as to close the opening. Therefore, as shown in FIG. 2, two gas separation membranes 3, 3 arranged vertically are arranged on the wall 41. That is, the two gas separation membranes 3, 3 are arranged so that the second faces 32 face each other. This enables separation of carbon dioxide CO2 on both the upper and lower sides of the gas separation membrane unit 2. The number of gas separation membranes 3 provided on one wall 41 is not particularly limited, and may be one or three or more. In addition, in this embodiment, the gas separation membrane 3 is arranged so as to intersect with the Z axis, but a gas separation membrane 3 arranged so as to intersect with the X axis may be added.

[0038] The exhaust port 42 is tubular and communicates with the internal space S1. As shown in FIG. 1, an exhaust pump 6 is connected to the exhaust port 42. The exhaust pump 6 is operated to exhaust the internal space S1 containing carbon dioxide CO2 through the exhaust port 42. The pressure of the internal space S1 when the exhaust pump 6 is operating may be less than atmospheric pressure, preferably 10 kPa or less, more preferably 1 kPa or less. This ensures a sufficient pressure difference between the first surface 31 side and the second surface 32 side of the gas separation membrane 3, and can sufficiently increase the separation efficiency of carbon dioxide CO2. The lower limit of the pressure of the internal space S1 is not particularly limited, but is preferably 0.001 Pa or more, more preferably 0.1 Pa or more, in consideration of the introduction cost and running cost of the exhaust pump 6, the deformation resistance of the gas separation membrane 3, and the like. In addition, taking these points into consideration, the air pressure difference between the internal space S1 and the outside is preferably set to 0.001 Pa or more and 10 kPa or less, and more preferably set to 0.1 Pa or more and 1 kPa or less.

[0039] Examples of materials constituting the wall body 41 and the exhaust port 42 include resin materials, metal materials, ceramic materials, etc. Also, composite materials containing these materials may be used.

[0040] The wall 41 and the gas separation membrane 3 are bonded together so as not to impair airtightness. The bonding method is not particularly limited, but examples thereof include bonding with an adhesive, bonding by sandwiching, and bonding by fusion.

[0041] The height h of the wall 41 in the Z-axis direction is not particularly limited, but is preferably 5 mm to 30 cm, and more preferably 1 cm to 10 cm. This makes it possible to prevent the gas separation device 1 from becoming large even when multiple gas separation membrane units 2 are stacked.

[0042] The maximum length of the wall 41 along the XY plane is not particularly limited, but is preferably from 5 cm to 2 m, and more preferably from 10 cm to 1 m. This makes it possible to arrange a sufficiently large gas separation membrane 3, and realizes a gas separation membrane unit 2 that can ensure a sufficient gas permeation rate.

[0043] 1.2.3.First convex structure The first convex structures 5 are members that protrude from the first surface 31 of the gas separation membrane 3 and the outer surface 412 of the wall body 41 .

[0044] Fig. 3 is a schematic diagram in which an example of a gas flow is added to a part of the cross-sectional view shown in Fig. 2. Fig. 4 is a schematic diagram in which an example of a gas flow is added to a cross-sectional view of a model (conventional model) in which the first convex structures 5 are omitted.

[0045] As shown in FIG. 4, when the first convex structure 5 is not provided, the airflow of the mixed gas G1 becomes a laminar flow that flows along the first surface 31 or the outer surface 412. In this specification, the term "laminar flow" refers to an airflow that flows parallel to the first surface 31 or the outer surface 412. The flow rate of the laminar flow tends to decrease closer to the surface of the object. Therefore, in the vicinity of the first surface 31 of the gas separation membrane 3, the gas exchange efficiency of the mixed gas G1 decreases, and the concentration of carbon dioxide CO2 decreases. In FIG. 4, the region where the concentration of carbon dioxide CO2 is low is marked with a dot as a "low concentration region LC". When such a low concentration region LC occurs, the gas separation membrane 3 does not function sufficiently, and the separation efficiency of carbon dioxide CO2 decreases.

[0046] In contrast, when the first convex structure 5 is provided on the first surface 31 or the outer surface 412, as shown in FIG. 3, a part of the airflow of the mixed gas G1 hits the first convex structure 5, generating a turbulent flow downstream. This turbulent flow includes, for example, a flow that stirs the mixed gas G1 in the Z-axis direction. Therefore, even if the concentration of carbon dioxide CO2 on the first surface 31 side decreases due to the permeation of carbon dioxide CO2 through the gas separation membrane 3, the concentration is likely to recover on the downstream side of the first convex structure 5 because new mixed gas G1 continues to be replenished due to the influence of the turbulent flow. As a result, in the gas separation device 1 shown in FIG. 3, the occurrence of a low concentration region LC as shown in FIG. 4 is suppressed, and the decrease in the separation efficiency of carbon dioxide CO2 can be suppressed.

[0047] The shape, material, arrangement, etc. of the first convex structures 5 are not particularly limited as long as they are members that generate turbulent flow as described above. In Fig. 1, the first convex structures 5 are arranged on the first surface 31 of the gas separation membrane 3 and on the outer surface 412 of the wall body 41. When a plurality of gas separation membranes 3 are arranged on one wall body 41, it is preferable to arrange the first convex structures 5 on the first surface 31 or the outer surface 412 in accordance with the arrangement of each gas separation membrane 3. This makes it possible to suppress a decrease in the separation efficiency of carbon dioxide CO2 in each gas separation membrane 3.

[0048] The number of first convex structures 5 may be one, but is preferably two or more. By providing a plurality of first convex structures 5, it is possible to generate turbulent flow in each part of the gas separation membrane 3. As a result, it is possible to particularly suppress a decrease in the separation efficiency of carbon dioxide CO2.

[0049] The first convex structures 5 may be provided on only one of the first surface 31 of the gas separation membrane 3 and the outer surface 412 of the wall body 41, but are preferably provided on both. This can particularly suppress the decrease in separation efficiency of carbon dioxide CO2. When provided on the outer surface 412, it is preferable to provide it on the upstream side of the gas separation membrane 3 in the flow of the mixed gas G1. Specifically, it is preferable that the first convex structures 5 protrude from the outer surface 412 on the upstream side of the flow of the mixed gas G1 relative to the gas separation membrane 3. This makes it easier to generate turbulence on the first surface 31 of the gas separation membrane 3 because the gas separation membrane 3 is located downstream of the first convex structures 5. This makes it easier to obtain the effect of suppressing the decrease in separation efficiency.

[0050] Furthermore, when the first convex structures 5 are provided on the wall 41, it is possible to avoid a decrease in the effective area of ​​the gas separation membrane 3 compared to when the first convex structures 5 are provided on the gas separation membrane 3. This makes it possible to suppress a decrease in separation efficiency. On the other hand, when the first convex structures 5 are provided on the gas separation membrane 3, it is possible to generate turbulence over a wide area of ​​the gas separation membrane 3. This makes it possible to enjoy the effect of suppressing a decrease in separation efficiency over a wide area.

[0051] In addition, since the airflow of the mixed gas G1 is along the Y axis, it is preferable that the first convex structures 5 are aligned along the X axis. This allows turbulent flow to be generated over a wide range in the X axis direction. Furthermore, in FIG. 1, multiple rows of the first convex structures 5 extending along the X axis are arranged in the Y axis direction. This allows turbulent flow to be generated over a wide range in the Y axis direction.

[0052] Furthermore, the positions of the first convex structures 5 in the rows in the X-axis direction may be aligned or shifted from each other. In the latter case, the regions in which turbulence occurs are also shifted, so that turbulence can be generated over a wider range of the gas separation membrane 3.

[0053] FIG. 5 is a partially enlarged view showing the first convex structure 5 of FIG. The shape of the first convex structure 5 is not particularly limited, but for example, when the installation surface is a surface facing the Z-axis positive side, it is preferable that the cross-sectional area in the XY plane gradually decreases toward the Z-axis positive side as shown in Fig. 5. With such a shape, it is possible to generate a turbulent flow without significantly impairing the flow rate of the mixed gas G1. As a result, it is possible to particularly suppress a decrease in the separation efficiency of carbon dioxide CO2.

[0054] The height H of the first convex structure 5 in the Z-axis direction is not particularly limited, but is preferably 0.1 mm or more and 50 mm or less, more preferably 1 mm or more and 30 mm or less, and even more preferably 3 mm or more and 20 mm or less. If the height H is within the above range, an appropriate turbulent flow can be generated without significantly impairing the flow rate of the mixed gas G1. If the height H is below the lower limit, depending on the flow rate of the mixed gas G1 and the size of the first convex structure 5, etc., there is a risk that turbulence cannot be generated sufficiently. On the other hand, if the height H exceeds the upper limit, depending on the size of the first convex structure 5, etc., there is a risk that the flow rate of the mixed gas G1 will be reduced.

[0055] The length L of the first convex structure 5 in the Y-axis direction is not particularly limited, but is preferably 1 mm or more and 200 mm or less, more preferably 3 mm or more and 100 mm or less, and even more preferably 5 mm or more and 50 mm or less.

[0056] When the width of the first convex structure 5 in the X-axis direction is W, the ratio W / L of the width W to the length L is preferably 0.01 to 2.0, more preferably 0.02 to 1.0, and even more preferably 0.03 to 0.7. If the ratio W / L is within the above range, appropriate turbulence can be generated without impairing the flow rate of the mixed gas G1. If the ratio W / L is below the lower limit, the width of the region where turbulence is generated may be insufficient. On the other hand, if the ratio W / L is above the upper limit, the flow rate of the mixed gas G1 may be impaired or appropriate turbulence may not be generated.

[0057] The first convex structures 5 are disposed on the first surface 31 or the outer surface 412 by, for example, adhesion, fusion or other methods. The first convex structures 5 may be integral with the first surface 31 or the outer surface 412. In other words, the first convex structures 5 may be formed by molding a part of the gas separation membrane 3 or the wall body 41. However, from the viewpoint of ease of manufacture, it is preferable that the gas separation membrane 3 is separate from the first convex structures 5.

[0058] Furthermore, if the gas permeability of the gas separation membrane 3 to carbon dioxide CO2 is within the above range, the significance of providing the first convex structures 5 becomes more evident. Specifically, when the gas permeability is high, the rate at which the concentration of carbon dioxide CO2 decreases on the first surface 31 of the gas separation membrane 3 is high. For this reason, if the supply of new mixed gas G1 is delayed, it becomes difficult to maintain the concentration of carbon dioxide CO2 high.

[0059] Fig. 6 is a graph showing the relationship between the gas permeability of carbon dioxide through the gas separation membrane 3 and the concentration of carbon dioxide on the first surface 31 of the gas separation membrane 3. The graph shown in Fig. 6 plots the concentration of carbon dioxide on the first surface 31 one second after the mixed gas G1 is supplied, when the flow rate of the mixed gas G1 with a carbon dioxide concentration of 400 ppm supplied onto the first surface 31 is zero. In this case, since the flow rate is zero, it is assumed that carbon dioxide spreads in the mixed gas G1 only by the effect of diffusion. In addition, the gas selectivity of the gas separation membrane 3 is assumed to be infinite.

[0060] As is clear from Fig. 6, when the carbon dioxide gas permeability of the gas separation membrane 3 becomes 1000 GPU or more, the carbon dioxide concentration drops sharply. For this reason, when the gas permeability is 1000 GPU or more, the provision of the first convex structures 5 becomes even more significant. By providing the first convex structures 5, it is possible to realize a gas separation device 1 that makes the most of the high gas permeability of the gas separation membrane 3.

[0061] 7 is a graph showing the relationship between the flow velocity of mixed gas G1 and the concentration ratio of carbon dioxide in the gas separation membrane 3. The flow velocity of mixed gas G1 is the velocity in a direction parallel to the first surface 31 of the gas separation membrane 3. The concentration ratio of carbon dioxide is the ratio of the concentration of carbon dioxide on the second surface 32 side to the concentration of carbon dioxide on the first surface 31 side.

[0062] As is clear from Fig. 7, when the first convex structure 5 is provided, the concentration ratio of carbon dioxide CO2 is higher than when the first convex structure 5 is not provided. In particular, it can be seen that this tendency is remarkable when the flow velocity of the mixed gas G1 is low. Therefore, by providing the first convex structure 5, even when a flow velocity is given to the mixed gas G1 using a fan, it is possible to realize a sufficiently high concentration ratio while suppressing the power consumption of the fan.

[0063] 7, it can be said that the significance of providing the first convex structure 5 becomes greater when the flow velocity of the mixed gas G1 is within the range of more than 0 m / s and not more than 5 m / s. Note that the concentration ratio in Fig. 7 is a calculated value when the mass concentration of carbon dioxide on the first surface 31 side is 400 ppm, the gas selectivity of the gas separation membrane 3 is 10, and the gas permeability of the gas separation membrane 3 to carbon dioxide is 10,000 GPU.

[0064] 1.3.Exhaust Pump Examples of the exhaust pump 6 include dry pumps such as screw pumps and scroll pumps, oil rotary pumps, and turbo molecular pumps. Of these, dry pumps are preferably used, and screw pumps are more preferably used. These pumps are useful as the exhaust pump 6 because they do not use oils or liquids, so there is no risk of contaminating the internal space S1, and they consume low power.

[0065] 2. Second embodiment Next, a gas separation membrane unit and a gas separation device according to a second embodiment will be described. FIG. 8 is a cross-sectional view showing the configuration of a gas separation device 1 according to the second embodiment.

[0066] The second embodiment will be described below, but in the following description, the differences from the first embodiment will be mainly described, and a description of similar points will be omitted.

[0067] The second embodiment is similar to the first embodiment except that a mixed gas supply unit 7 is further provided.

[0068] 8, the gas separation device 1 according to the second embodiment includes a mixed gas supply unit 7 in addition to the above-mentioned gas separation membrane unit 2. The mixed gas supply unit 7 has a mixed gas flow path section 72, a mixed gas inlet section 74, and a mixed gas outlet section 76.

[0069] The mixed gas flow passage section 72 is a flow passage through which the mixed gas G1 flows, which is provided above and below the gas separation membrane unit 2 and is defined by a wall surface 33 including the first surface 31 of the gas separation membrane 3. Specifically, as shown in FIG. 8, the mixed gas flow passage section 72 has an upper plate 721 provided at the top of the gas separation membrane unit 2, a lower plate 722 provided at the bottom, and two side plates 723 covering the side surfaces intersecting the X-axis. The upper plate 721 and the lower plate 722 sandwich the two gas separation membrane units 2, 2 in the Z-axis direction. The two side plates 723 also sandwich the two gas separation membrane units 2, 2 in the X-axis direction. Therefore, the first surface 31, the inner surface intersecting the X-axis, and the inner surface intersecting the Z-axis form the wall surface 33. Note that only one side plate 723 is shown in FIG. 8.

[0070] Examples of materials constituting the upper plate 721, the lower plate 722, and the side plate 723 include resin materials, metal materials, ceramic materials, etc. Also, composite materials containing these materials may be used.

[0071] 8 has a second convex structure 8 protruding from the wall surface 33. This allows the turbulence caused by the second convex structure 8 to act on the mixed gas G1 present in the vicinity of the first surface 31. As a result, the decrease in the concentration of carbon dioxide CO2 on the first surface 31 can be further suppressed.

[0072] The configuration of the second convex structures 8 is the same as that of the first convex structures 5, except for the arrangement. The second convex structures 8 may be arranged on the wall surface 33, but is preferably arranged on the opposing surface of the first surface 31. This makes it easier for the turbulence caused by the second convex structures 8 to act on the mixed gas G1 present in the vicinity of the first surface 31.

[0073] The mixed gas inlet 74 introduces the mixed gas G1 into the mixed gas flow path 72. The mixed gas inlet 74 shown in Fig. 8 has an air supply fan 742. The air supply fan 742 supplies the mixed gas G1 toward the inside of the mixed gas flow path 72. This makes it possible to impart a flow velocity to the mixed gas G1 in the mixed gas flow path 72.

[0074] The mixed gas discharge section 76 discharges the mixed gas G1' from the mixed gas flow path section 72. The mixed gas G1' is the mixed gas after carbon dioxide CO2 has been separated in the gas separation membrane unit 2. The mixed gas discharge section 76 shown in FIG. 8 has an exhaust fan 762. The exhaust fan 762 exhausts the mixed gas G1' toward the outside of the mixed gas flow path section 72. This makes it possible to quickly discharge the mixed gas G1' having a low concentration of carbon dioxide CO2, thereby more reliably suppressing a decrease in the concentration of carbon dioxide CO2 on the first surface 31 of the gas separation membrane 3.

[0075] The second embodiment as described above also provides the same effects as the first embodiment. Moreover, in the second embodiment, by providing the mixed gas flow passage section 72, even when the mixed gas G1 is exhaust gas or the like having a higher concentration of carbon dioxide CO2 than the atmosphere, the carbon dioxide CO2 can be separated while preventing the mixed gas G1 from being diluted with the atmosphere. Therefore, even when the mixed gas G1 originally has a high concentration of carbon dioxide CO2, for example, the mixed gas G1 contains a high concentration of carbon dioxide CO2 generated in various plants, the decrease in separation efficiency can be suppressed.

[0076] 3. Advantages of the above embodiment As described above, the gas separation membrane unit 2 according to the embodiment has the gas separation membrane 3, the gas flow path section 4, and the first convex structure 5. The gas separation membrane 3 separates carbon dioxide CO2 (a predetermined gas component) contained in the mixed gas G1 supplied to the first surface 31 by allowing it to permeate through the second surface 32, which is the reverse surface of the first surface 31. The gas flow path section 4 has a wall 41 that defines an internal space S1 through which the separated gas containing carbon dioxide CO2 flows. The first convex structure 5 protrudes from at least one of the first surface 31 of the gas separation membrane 3 and the outer surface 412 of the wall 41.

[0077] With this configuration, the first convex structures 5 cause turbulence in the airflow formed on the first surface 31 of the gas separation membrane 3, so that even if the concentration of carbon dioxide CO2 in the mixed gas G1 on the first surface 31 decreases due to the action of the gas separation membrane 3, new mixed gas G1 continues to be rapidly supplied onto the first surface 31. As a result, even if carbon dioxide CO2 permeates the gas separation membrane 3, the concentration of carbon dioxide CO2 on the first surface 31 is unlikely to decrease, and a gas separation membrane unit 2 in which a decrease in separation efficiency is suppressed can be obtained.

[0078] Moreover, the gas separation membrane unit 2 according to the embodiment has two gas separation membranes 3, 3 arranged with their second surfaces 32 facing each other.

[0079] With this configuration, carbon dioxide CO2 can be separated on both sides (upper and lower sides) of the gas separation membrane unit 2.

[0080] In the gas separation membrane unit 2 according to the embodiment, the first convex structures 5 are disposed on the first surfaces 31 of the two gas separation membranes 3, 3, respectively.

[0081] According to such a configuration, a decrease in the separation efficiency of carbon dioxide CO2 in each gas separation membrane 3 can be suppressed.

[0082] Moreover, the protruding height of the first convex structures 5 is preferably 0.1 mm or more and 50 mm or less.

[0083] If the height H is within the above range, an appropriate turbulent flow can be generated without significantly impairing the flow rate of the mixed gas G1.

[0084] The gas separation membrane 3 preferably has a gas permeability to carbon dioxide of 5,000 GPU or more and 100,000 GPU or less.

[0085] Such a configuration can realize a gas separation membrane 3 that can reduce the amount of energy input required for separation, specifically, that can reduce the pressure difference between the first surface 31 and the second surface 32. Also, a gas separation membrane unit 2 can be realized that can maximize the effect of the first convex structures 5 and that allows easy procurement of the gas separation membrane 3.

[0086] Moreover, the gas separation device 1 according to the embodiment includes the gas separation membrane unit 2 according to the embodiment, and an exhaust pump 6. The exhaust pump 6 exhausts carbon dioxide CO2 (a predetermined gas component) flowing through the internal space S1 of the gas channel section 4.

[0087] According to this configuration, the internal space S1 can be decompressed to a pressure lower than atmospheric pressure, and a pressure difference can be generated between the first surface 31 side and the second surface 32 side of the gas separation membrane 3. A gas separation device 1 capable of separating carbon dioxide CO2 by utilizing this pressure difference can be obtained. In addition, since the first convex structure 5 generates turbulence in the airflow formed on the first surface 31 of the gas separation membrane 3, even if the concentration of carbon dioxide CO2 in the mixed gas G1 on the first surface 31 decreases due to the action of the gas separation membrane 3, new mixed gas G1 continues to be rapidly supplied onto the first surface 31. As a result, even if carbon dioxide CO2 permeates the gas separation membrane 3, the concentration of carbon dioxide CO2 on the first surface 31 is unlikely to decrease, and a gas separation device 1 in which a decrease in separation efficiency is suppressed can be obtained.

[0088] Moreover, the gas separation device 1 according to the embodiment includes a mixed gas supply unit 7. The mixed gas supply unit 7 has a mixed gas flow path section 72, a mixed gas inlet section 74, and a mixed gas outlet section 76. The mixed gas flow path section 72 is defined by a wall surface 33 including the first surface 31, and the mixed gas G1 flows through it. The mixed gas inlet section 74 introduces the mixed gas G1 into the mixed gas flow path section 72. The mixed gas outlet section 76 discharges the mixed gas G1' from the mixed gas flow path section 72.

[0089] According to this configuration, even if the mixed gas G1 is exhaust gas or the like having a higher concentration of carbon dioxide CO2 than the atmosphere, the carbon dioxide CO2 can be separated while preventing the mixed gas G1 from being diluted with the atmosphere.

[0090] Moreover, in the gas separation device 1 according to the embodiment, the mixed gas supply unit 7 has the second convex structure 8 protruding from the wall surface 33.

[0091] According to this configuration, the turbulence caused by the second convex structure 8 can also act on the mixed gas G1 present in the vicinity of the first surface 31. As a result, the decrease in the concentration of carbon dioxide CO2 on the first surface 31 can be further suppressed.

[0092] In the gas separation device 1 according to the embodiment, the first convex structures 5 protrude from the outer surface 412 of the wall body 41 upstream of the gas separation membrane 3 in the flow of the mixed gas G1.

[0093] With this configuration, the gas separation membrane 3 is located downstream of the first convex structures 5, which makes it easier to generate turbulence on the first surface 31 of the gas separation membrane 3. This makes it easier to obtain the effect of suppressing a decrease in separation efficiency.

[0094] Moreover, the gas separation device 1 according to the embodiment includes at least two gas separation membrane units 2 that are spaced apart from each other in a direction intersecting with the first surface 31.

[0095] With such a configuration, it is possible to realize a gas separation device 1 with high separation efficiency of carbon dioxide CO2.

[0096] While the gas separation membrane unit and the gas separation device according to the present invention have been described above based on the illustrated embodiment, the present invention is not limited to this.

[0097] For example, the gas separation membrane unit and gas separation device of the present invention may be configured in such a way that each part of the above-described embodiments is replaced with any component having a similar function, or any component may be added to the above-described embodiments. [Explanation of symbols]

[0098] Reference Signs List 1...gas separation device, 2...gas separation membrane unit, 3...gas separation membrane, 4...gas flow path section, 5...first convex structure, 6...exhaust pump, 7...mixed gas supply unit, 8...second convex structure, 31...first surface, 32...second surface, 33...wall surface, 41...wall body, 42...exhaust port, 72...mixed gas flow path section, 74...mixed gas inlet section, 76...mixed gas outlet section, 412...outer surface, 721...upper plate, 722...lower plate, 723...side plate, 742...air supply fan, 762...exhaust fan, CO2...carbon dioxide, G1...mixed gas, G1'...mixed gas, H...height, L...length, LC...low concentration region, S1...internal space, W...width, d...distance, h...height

Claims

1. a gas separation membrane that separates a predetermined gas component contained in a mixed gas supplied to a first surface by transmitting the predetermined gas component to a second surface that is the reverse side of the first surface; a gas flow path portion having a wall defining an internal space through which the separated predetermined gas component flows; a first convex structure protruding from at least one of the first surface of the gas separation membrane and an outer surface of the wall; A gas separation membrane unit comprising:

2. The gas separation membrane unit according to claim 1 , comprising two of the gas separation membranes arranged such that the second surfaces face each other.

3. The gas separation membrane unit according to claim 2 , wherein the first convex structures are disposed on the first surfaces of the two gas separation membranes, respectively.

4. 4. The gas separation membrane unit according to claim 1, wherein the protruding height of the first convex structures is 0.1 mm or more and 50 mm or less.

5. 4. The gas separation membrane unit according to claim 1, wherein the gas separation membrane has a carbon dioxide gas permeability of 5,000 GPU or more and 100,000 GPU or less.

6. A gas separation membrane unit according to any one of claims 1 to 3, an exhaust pump that exhausts the predetermined gas component flowing through the internal space of the gas flow path portion; A gas separation device comprising:

7. a mixed gas flow path portion defined by a wall surface including the first surface, through which the mixed gas flows; a mixed gas inlet portion that introduces the mixed gas into the mixed gas flow passage portion; and a mixed gas discharge section that discharges the mixed gas from the mixed gas flow passage section; A mixed gas supply unit having The gas separation device of claim 6 .

8. The gas separation device according to claim 7 , wherein the mixed gas supply unit has a second convex structure protruding from the wall surface.

9. The gas separation device according to claim 7 , wherein the first convex structure protrudes from an outer surface of the wall body upstream of the gas separation membrane in the flow of the mixed gas.

10. The gas separation device according to claim 6 , comprising at least two of the gas separation membrane units arranged spaced apart from each other in a direction intersecting the first surface.

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