Gas separation membrane unit and gas separation device

Abstract

The present disclosure provides a gas separation membrane unit and a gas separation device which can maintain a high concentration of a predetermined gas component on the surface of a gas separation membrane and suppress a decrease in separation efficiency. The gas separation membrane unit is characterized by comprising: a gas separation membrane that separates a predetermined gas component contained in a mixed gas supplied to a first surface by allowing the gas component to permeate through a second surface, which is the back surface of the first surface; a gas flow path part having a wall body defining an internal space for the flow of the predetermined gas component that has been separated; and a first convex structure protruding from at least one of the first surface of the gas separation membrane and the outer surface of the wall body.

Description

Technical Field

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

[0002] In order to achieve carbon neutrality or carbon negative emissions, research is underway to capture and recover carbon dioxide exhausted from thermal power plants and boiler facilities or carbon dioxide in the air. As such technology, a membrane separation method is known that 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. The gas separation method includes a step of supplying a mixed gas to one side of the gas separation membrane, wherein the 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) through the gas separation membrane is performed under the condition that the pressure difference between the two sides of the gas separation membrane is less than one atmospheric pressure.

[0004] According to this gas separation method, even under mild conditions such as a pressure difference between both surfaces of the gas separation membrane being 1 atmospheric pressure or less, the gas (A) can be separated satisfactorily.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent document 1: Japanese Patent Application Publication No. 2023-033590.

[0008] In the membrane separation method, improving the separation efficiency of a predetermined gas component becomes a technical problem. In order to improve the separation efficiency of the gas separation membrane, it is necessary to maintain a high concentration of the predetermined gas component on the upstream side of the gas separation membrane. However, when the predetermined gas component permeates the gas separation membrane, the concentration on the upstream side decreases, resulting in a decrease in the separation efficiency.

[0009] Therefore, there is a need to realize a gas separation device in which even when a predetermined gas component permeates through a gas separation membrane, the concentration is unlikely to decrease and a decrease in separation efficiency is suppressed. Summary of the invention

[0010] A gas separation membrane unit according to an application example of the present invention comprises:

[0011] 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 a back surface of the first surface;

[0012] a gas flow path portion having a wall defining an inner space for the separated predetermined gas component to flow; and

[0013] A first convex structure protrudes from at least one of the first surface of the gas separation membrane and an outer surface of the wall body.

[0014] The gas separation device according to the application example of the present invention comprises:

[0015] A gas separation membrane unit according to an application example of the present invention; and

[0016] An exhaust pump exhausts the predetermined gas component flowing in the internal space of the gas flow path portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a perspective view showing the structure of the gas separation device according to the first embodiment.

[0018] Figure 2 yes Figure 1 A cross-sectional view of a gas separation device is shown.

[0019] Figure 3 Yes Figure 2 A schematic diagram showing an example of the flow of gas is additionally recorded in part of the cross-sectional view shown.

[0020] Figure 4 This is a schematic diagram of an example in which the flow of gas is recorded in addition to the cross-sectional view of the model (model of the conventional example) in which the first convex structure is omitted.

[0021] Figure 5 It is shown Figure 1 A partially enlarged view of the first convex structure.

[0022] Figure 6 This is a graph showing the relationship between the carbon dioxide permeability of the gas separation membrane and the carbon dioxide concentration on the first surface of the gas separation membrane.

[0023] Figure 7 This is a graph showing the relationship between the flow rate of the mixed gas and the concentration ratio of carbon dioxide in the gas separation membrane.

[0024] Figure 8 It is a cross-sectional view showing the structure of a gas separation device according to the second embodiment.

[0025] Explanation of symbols

[0026] 1. Gas separation device; 2. Gas separation membrane unit; 3. Gas separation membrane; 4. Gas flow path; 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; 74. Mixed gas inlet; 76. Mixed gas outlet; 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 area; S1, inner space; W, width; d, distance; h, height. DETAILED DESCRIPTION

[0027] Hereinafter, the gas separation membrane unit and the gas separation apparatus of the present invention will be described in detail based on the embodiments shown in the drawings.

[0028] 1. First Implementation

[0029] First, a gas separation membrane unit and a gas separation device according to a first embodiment will be described.

[0030] Figure 1 It is a perspective view showing the structure of the gas separation device 1 according to the first embodiment. Figure 2 yes Figure 1 A cross-sectional view of a gas separation device 1 is shown.

[0031] 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, and the top side of the arrow is regarded as "positive" and the base side of the arrow is regarded as "negative". In the following description, for example, "X-axis direction" refers to both the positive direction and the negative direction of the X-axis. The Y-axis direction and the Z-axis direction are also the same. In addition, in the following description, in particular, the positive side of the Z-axis is referred to as "upper" and the negative side of the Z-axis is referred to as "lower". However, the Z-axis can intersect with the vertical axis without being parallel to the vertical axis.

[0032] 1.1. Overview

[0033] Figure 1The gas separation device 1 shown has two gas separation membrane units 2, 2 (gas separation membrane units involved in the embodiment) and an exhaust pump 6. The gas separation membrane unit 2 has a gas separation membrane 3, a gas flow path portion 4 and a first convex structure 5. The gas separation membrane 3 allows the carbon dioxide CO2 (predetermined gas component) contained in the mixed gas G1 supplied to the first surface 31 (front surface) to be preferentially permeated through the second surface 32 (back surface) over other gas components to be separated. The gas flow path portion 4 has a wall body 41 that defines an internal space S1 for the gas containing carbon dioxide CO2 (gas having a higher concentration of carbon dioxide CO2 than the mixed gas G1) to be preferentially separated and extracted to flow. The first convex structure 5 protrudes from the first surface 31 of the gas separation membrane 3 and the outer surface 412 of the wall body 41. The wall body 41 holds the gas separation membrane 3, and the outer surface 412 of the wall body 41 provided with the first convex structure 5 is arranged on the periphery of the gas separation membrane 3.

[0034] In such a gas separation membrane unit 2, the first convex structure 5 causes turbulence under predetermined conditions with respect to the gas flow formed on the first surface 31 of the gas separation membrane 3. Thus, even if the concentration of carbon dioxide CO2 in the mixed gas G1 on the first surface 31 decreases due to the permeation of the gas separation membrane 3, new mixed gas G1 can be effectively supplied to the first surface 31. As a result, the concentration of carbon dioxide CO2 on the first surface 31 can be maintained high, and the reduction in the separation efficiency of the gas separation membrane 3 can be suppressed.

[0035] 1.2. Gas separation membrane unit

[0036] exist Figure 1 In the gas separation device 1 shown, two gas separation membrane units 2, 2 are arranged to be separated from each other in the Z-axis direction. Since the gas separation device 1 includes a plurality of gas separation membrane units 2, 2, a gas separation device 1 having high separation efficiency of carbon dioxide CO2 can be realized.

[0037] The arrangement direction of the two gas separation membrane units 2, 2 is not limited to the Z-axis direction (the direction intersecting the first surface 31), and any direction intersecting the first surface 31 is acceptable. However, if it is the Z-axis direction, the occupied area of ​​the gas separation device 1 can be reduced.

[0038] The exhaust pump 6 is connected to the gas flow path portion 4 to exhaust the internal space S1 containing carbon dioxide CO2. As a result, the internal space S1 is depressurized to below atmospheric pressure, so that a pressure difference is generated between the first surface 31 side and the second surface 32 side of the gas separation membrane 3. In the gas separation membrane 3, this pressure difference can be used as a driving force to allow carbon dioxide CO2 to pass through for separation.

[0039] The gas separation membrane unit 2 is placed in an environment where a mixed gas G1 exists. The mixed gas G1 contains carbon dioxide CO2 as a gas component to be separated and other gas components (non-target components). The mixed gas G1 is not particularly limited, and may be, for example, air, exhaust gas discharged from a factory or the like. 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 air, they are nitrogen or oxygen, etc.

[0040] The gas separation membrane unit 2 is exposed to the gas flow of the mixed gas G1. In the various figures of the present application, arrows are used to indicate the direction of the gas flow of the mixed gas G1. In the present embodiment, the gas flow of the mixed gas G1 is formed in a manner from the negative side of the Y-axis to the positive side of the Y-axis. By being exposed to the gas flow, the mixed gas G1 with a high concentration of carbon dioxide CO2 can be continuously supplied. As a result, the separation efficiency of carbon dioxide CO2 of the gas separation membrane unit 2 can be maintained at a high level. In addition, in the present specification, with respect to the gas flow of the mixed gas G1, the negative side of the Y-axis is referred to as "upstream", and the positive side of the Y-axis is referred to as "downstream".

[0041] When the mixed gas G1 is air, the airflow of the mixed gas G1 may be a natural flow of air or a flow caused by a fan not shown. When the mixed gas G1 is exhaust gas, the airflow of the mixed gas G1 may be a flow caused by a discharge source or a flow caused by a fan not shown. Therefore, the gas separation device 1 may have a fan that generates an airflow of the mixed gas G1.

[0042] The distance d between the gas separation membrane units 2 in the Z-axis direction is set to be longer than the protrusion height of the first convex structures 5 , for example, about 1 mm to 1 m, preferably 10 mm to 10 cm.

[0043] The number of the gas separation membrane units 2 included in the gas separation device 1 is not limited to two, and may be one, or may be three or more.

[0044] 1.2.1. Gas separation membrane

[0045] The gas separation membrane 3 has a first surface 31 and a second surface 32 that are in a positive and negative relationship with each other. The gas separation membrane 3 allows the carbon dioxide CO2 contained in the mixed gas G1 supplied to the first surface 31 side to selectively or preferentially permeate the second surface 32 side over other gas components. Therefore, the gas separation membrane 3 has a property that the permeability of carbon dioxide CO2 is greater than the permeability of non-target components (the property that the gas selectivity ratio of carbon dioxide CO2 is high). Hereinafter, the ratio of the permeability of carbon dioxide to the permeability of nitrogen is referred to as "gas selectivity ratio".

[0046] The gas selectivity of the gas separation membrane 3 is preferably 3 or more, more preferably 10 or more and 1000 or less. When the gas selectivity is within the above range, the gas separation membrane 3 can efficiently separate and recover carbon dioxide CO2 in the mixed gas G1.

[0047] The nitrogen permeability of the gas separation membrane 3 and the carbon dioxide permeability of the gas separation membrane 3 are measured according to the permeability test method (Part 1: differential pressure method) specified in JIS K7126-1:2006. The measurement uses a permeability measuring device. As an example of a permeability measuring device, GTR-11A / 31A manufactured by GTR TEC Co., Ltd. can be cited. In this device, the gas that permeates the gas separation membrane 3 is introduced into a gas chromatograph to measure the permeability of each component.

[0048] In the gas separation membrane 3, the permeability of carbon dioxide is preferably greater than 1000 GPU, more preferably greater than 5000 GPU and less than 100000 GPU, and further preferably greater than 10000 GPU and less than 50000 GPU. As a result, it is possible to reduce the amount of energy input required for separation. Specifically, it is possible to achieve a gas separation membrane 3 that can reduce the pressure difference between the first surface 31 side and the second surface 32 side. In addition, when the permeability of carbon dioxide in the gas separation membrane 3 is lower than the lower limit value, the separation of carbon dioxide requires more energy, which may reduce the economic efficiency of the operation of the gas separation device 1. On the other hand, when the permeability of carbon dioxide in the gas separation membrane 3 is higher than the upper limit value, it is possible to increase the cost required for the manufacture (procurement and supply) of the gas separation membrane 3. In addition, 1 GPU is 3.35×10 -10 mol·m -2 ·s -1 ·Pa -1 .

[0049] 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 further preferably 10 nm to 10 μm.

[0050] The average thickness of the gas separation membrane 3 is an average value of thicknesses measured at 10 locations of the gas separation membrane 3. The thickness of the gas separation membrane 3 can be measured using, for example, a thickness gauge.

[0051] The size of the gas separation membrane 3 is not particularly limited, but the maximum length is preferably 5 cm to 2 m, more preferably 10 cm to 1 m. This allows the gas separation membrane 3 to have a mechanical strength that can withstand a pressure difference and ensure a sufficient air permeability.

[0052] The gas separation membrane 3 may be a single layer or a composite layer formed by stacking multiple layers. In addition, the gas separation membrane 3 may be supported by a porous layer. In particular, when the thickness of the gas separation membrane 3 is 100 μm or less, it is preferred to stack the gas separation membrane 3 and the porous layer to improve the overall strength.

[0053] Examples of the constituent material of the gas separation membrane 3 include polymer materials, ceramic materials, and metal materials. The constituent material of the gas separation membrane 3 may be a composite material of these materials or a composite material of these materials and other materials.

[0054] Examples of polymer materials include polyolefin resins such as polyethylene and polypropylene, fluorine-containing resins such as polytetrafluoroethylene, polyvinyl fluoride and polyvinylidene fluoride, organic polysiloxanes (organic silicone resins), polystyrene, cellulose, cellulose acetate, polyurethane, polyacrylonitrile, polyphenylene ether, polysulfone, polyethersulfone, polyimide, polyaramid, and nylon.

[0055] Examples of the ceramic material include alumina, cordierite, mullite, silicon carbide, and zirconia, and examples of the metal material include stainless steel.

[0056] 1.2.2. Gas flow path

[0057] The gas flow path section 4 includes a wall body 41 defining an internal space S1 for the separated gas containing carbon dioxide CO 2 to flow, and an exhaust port 42 provided in the wall body 41 .

[0058] The wall 41 is a box body of a substantially rectangular parallelepiped shape extending along the XY plane and having a hollow interior. The internal space S1 is defined by the wall 41. In addition, a portion of each of the two surfaces intersecting the Z axis is opened, and the gas separation membrane 3 is arranged in such a manner as to close the opening. Therefore, on the wall 41, as shown in FIG. Figure 2 As shown, two gas separation membranes 3, 3 are arranged in an upper and lower manner. That is, the two gas separation membranes 3, 3 are arranged in a manner that the second surfaces 32 are opposite to each other. As a result, carbon dioxide CO2 can be separated on both the upper surface side and the lower surface side of the gas separation membrane unit 2. In addition, the number of gas separation membranes 3 provided on one wall body 41 is not particularly limited, and may be one or more than three. In addition, in the present embodiment, the gas separation membrane 3 is arranged in a manner intersecting the Z axis, but a gas separation membrane 3 arranged in a manner intersecting the X axis may be added.

[0059] The exhaust port 42 is tubular and communicates with the internal space S1. Figure 1As shown, an exhaust pump 6 is connected. By the operation of the exhaust pump 6, the internal space S1 containing carbon dioxide CO2 is exhausted through the exhaust port 42. The pressure of the internal space S1 when the exhaust pump 6 is running only needs to be less than the atmospheric pressure, preferably below 10kPa, and more preferably below 1kPa. Thus, it is possible to ensure a sufficient air pressure difference between the first surface 31 side and the second surface 32 side of the gas separation membrane 3, and the separation efficiency of carbon dioxide CO2 can be fully improved. In addition, the lower limit of the pressure of the internal space S1 is not particularly limited, but if the introduction cost or operating cost of the exhaust pump 6, the deformation resistance of the gas separation membrane 3, etc. are taken into account, it is preferably above 0.001Pa, and more preferably above 0.1Pa. In addition, based on these viewpoints, the air pressure difference between the internal space S1 and the outside is preferably above 0.001Pa and below 10kPa, and more preferably above 0.1Pa and below 1kPa.

[0060] As each constituent material of the wall body 41 and the exhaust port 42, for example, there can be mentioned a resin material, a metal material, a ceramic material, etc. Alternatively, a composite material containing these materials may be used.

[0061] The wall body 41 and the gas separation membrane 3 are bonded together so as not to impair airtightness. The bonding method is not particularly limited, and examples thereof include bonding using an adhesive, bonding by sandwiching or the like, bonding by welding or the like, and the like.

[0062] The height h of the wall 41 in the Z-axis direction is not particularly limited, but is preferably 5 mm to 30 cm, more preferably 1 cm to 10 cm. Thus, even when a plurality of gas separation membrane units 2 are stacked, the size of the gas separation device 1 can be avoided.

[0063] The maximum length of the wall 41 along the XY plane is not particularly limited, but is preferably 5 cm to 2 m, more preferably 10 cm to 1 m. This allows the gas separation membrane unit 2 to be configured with a gas separation membrane 3 of sufficient size and to ensure a sufficient gas permeability.

[0064] 1.2.3. First convex structure

[0065] 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 .

[0066] Figure 3 Yes Figure 2 A schematic diagram showing an example of the flow of gas is additionally recorded in part of the cross-sectional view shown. Figure 4 This is a schematic diagram of an example in which the flow of gas is recorded in addition to the cross-sectional view of a model (model of the conventional example) in which the first convex structure 5 is omitted.

[0067] like Figure 4 As shown, when the first convex structure 5 is not provided, the airflow of the mixed gas G1 becomes a laminar flow flowing along the first surface 31 or the outer surface 412. In this specification, "laminar flow" refers to an airflow flowing parallel to the first surface 31 or the outer surface 412. The flow rate of the laminar flow tends to decrease as it approaches the surface of an object. Therefore, near 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. Figure 4 In the figure, the area with low concentration of carbon dioxide CO 2 is marked with dots as "low concentration area LC". When such low concentration area LC is generated, the gas separation membrane 3 cannot fully function, and the separation efficiency of carbon dioxide CO 2 is reduced.

[0068] In contrast, when the first convex structure 5 is provided on the first surface 31 or the outer surface 412, as shown in FIG. Figure 3 As shown, a part of the gas flow of the mixed gas G1 collides with the first convex structure 5, generating turbulence on the downstream side. The turbulence includes, for example, agitating the flow of the mixed gas G1 along the Z-axis direction. Therefore, on the downstream side of the first convex structure 5, even if the concentration of carbon dioxide CO2 on the first surface 31 side is reduced due to the penetration of carbon dioxide CO2 of the gas separation membrane 3, new mixed gas G1 can be continuously supplied due to the influence of turbulence, so the concentration is easily restored. As a result, Figure 3 In the gas separation device 1 shown, the generation of Figure 4 The low concentration region LC as shown suppresses the reduction in the separation efficiency of carbon dioxide CO 2 .

[0069] The shape, material, and arrangement of the first convex structure 5 are not particularly limited, as long as they are components that generate the above-mentioned turbulent flow. Figure 1 In the embodiment, the first convex structure 5 is arranged on the first surface 31 of the gas separation membrane 3 and the outer surface 412 of the wall body 41. In addition, when a plurality of gas separation membranes 3 are arranged on one wall body 41, it is preferred to arrange the first convex structure 5 on the first surface 31 and the outer surface 412 in a manner that the arrangement of each gas separation membrane 3 is consistent. Thus, the reduction in the separation efficiency of carbon dioxide CO2 of each gas separation membrane 3 can be suppressed.

[0070] The number of the first convex structure 5 may be one, but preferably multiple. By providing multiple first convex structures 5, turbulence can be generated in each part of the gas separation membrane 3. As a result, the reduction in separation efficiency of carbon dioxide CO2 can be particularly suppressed.

[0071] The first convex structure 5 can be provided only on either the first surface 31 of the gas separation membrane 3 or the outer surface 412 of the wall body 41, but is preferably provided on both. Thus, it is possible to suppress the reduction in the separation efficiency of carbon dioxide CO2 in particular. In addition, when provided on the outer surface 412, it is preferably provided on the upstream side of the gas separation membrane 3 in the flow of the mixed gas G1. Specifically, it is preferred that the first convex structure 5 protrudes on the upstream side of the flow of the mixed gas G1 in the outer surface 412 closer to the gas separation membrane 3. Thus, since the gas separation membrane 3 is located on the downstream side of the first convex structure 5, turbulence is easily caused on the first surface 31 of the gas separation membrane 3. Thus, it is easier to obtain the effect of suppressing the reduction in separation efficiency.

[0072] In addition, when the first convex structure 5 is provided on the wall 41, it is possible to avoid a reduction in the effective area of ​​the gas separation membrane 3 compared to the case where it is provided on the gas separation membrane 3. Thus, it is possible to suppress a reduction in separation efficiency. On the other hand, when the first convex structure 5 is provided on the gas separation membrane 3, turbulence can be generated in a larger range of the gas separation membrane 3. Thus, it is possible to enjoy the effect of suppressing a reduction in separation efficiency in a larger range.

[0073] In addition, since the gas flow of the mixed gas G1 is along the Y axis, the first convex structures 5 are preferably arranged along the X axis. This can generate turbulence in a wide range in the X axis direction. Figure 1 In the embodiment, a plurality of rows of first convex structures 5 extending along the X-axis are arranged in the Y-axis direction. This allows turbulence to be generated in a wide range in the Y-axis direction.

[0074] Furthermore, the positions of the first convex structures 5 in the X-axis direction may coincide with or be offset in the rows of the first convex structures 5. In the latter case, since the regions where turbulence is generated are also offset, turbulence can be generated in a wider range of the gas separation membrane 3.

[0075] Figure 5 It is shown Figure 1 A partially enlarged view of the first convex structure 5.

[0076] The shape of the first convex structure 5 is not particularly limited, but for example, when the setting surface is a surface facing the positive side of the Z axis, as shown in FIG. Figure 5 As shown, the cross-sectional area on the XY plane is preferably a shape that gradually decreases toward the positive side of the Z axis. If it is such a shape, turbulence can be generated without significantly damaging the flow rate of the mixed gas G1. As a result, the reduction in the separation efficiency of carbon dioxide CO2 can be particularly suppressed.

[0077] The height H of the first convex structure 5 in the Z-axis direction is not particularly limited, but is preferably greater than 0.1 mm and less than 50 mm, more preferably greater than 1 mm and less than 30 mm, and further preferably greater than 3 mm and less than 20 mm. If the height H is within the range, appropriate turbulence can be generated without significantly damaging the flow rate of the mixed gas G1. In addition, when the height H is lower than the lower limit, turbulence may not be fully generated depending on the flow rate of the mixed gas G1 or the size of the first convex structure 5. On the other hand, when the height H exceeds the upper limit, the flow rate of the mixed gas G1 may be reduced depending on the size of the first convex structure 5.

[0078] The length L of the first convex structure 5 in the Y-axis direction is not particularly limited, but is preferably 1 mm to 200 mm, more preferably 3 mm to 100 mm, and further preferably 5 mm to 50 mm.

[0079] When the width of the first convex structure 5 in the X-axis direction is set to W, the ratio W / L of the width W to the length L is preferably greater than 0.01 and less than 2.0, more preferably greater than 0.02 and less than 1.0, and further preferably greater than 0.03 and less than 0.7. If the ratio W / L is within the range, appropriate turbulence can be generated without damaging the flow rate of the mixed gas G1. In addition, when the ratio W / L is lower than the lower limit, the width of the area where turbulence is generated may be insufficient. On the other hand, when the ratio W / L exceeds the upper limit, the flow rate of the mixed gas G1 may be damaged, or appropriate turbulence may not be generated.

[0080] The first convex structure 5 is arranged on the first face 31 or the outer surface 412 by, for example, bonding, welding, etc. In addition, the first convex structure 5 can be formed integrally with the first face 31 or the outer surface 412. That is, the first convex structure 5 can be formed as a part of the gas separation membrane 3 or the wall body 41. However, with respect to the gas separation membrane 3, from the viewpoint of easy manufacturing, etc., it is preferably separated from the first convex structure 5.

[0081] In addition, if the air permeability of the carbon dioxide CO2 of the gas separation membrane 3 is within the above range, the significance of providing the first convex structure 5 is more significant. Specifically, when the air permeability is high, the speed at which the concentration of carbon dioxide CO2 decreases on the first surface 31 of the gas separation membrane 3 is large. Therefore, when the supply of the new mixed gas G1 is delayed, it is difficult to maintain the concentration of carbon dioxide CO2 at a high level.

[0082] Figure 6 This is a graph showing the relationship between the carbon dioxide permeability of the gas separation membrane 3 and the carbon dioxide concentration on the first surface 31 of the gas separation membrane 3 . Figure 6The graph shown depicts the concentration of carbon dioxide on the first surface 31 one second after the flow rate of the mixed gas G1 supplied to the first surface 31 with a carbon dioxide concentration of 400 ppm is zero. In this case, since the flow rate is zero, it is assumed that carbon dioxide diffuses in the mixed gas G1 only by the effect of diffusion. In addition, it is assumed that the gas selectivity of the gas separation membrane 3 is infinite.

[0083] As per Figure 6 It can be seen that when the carbon dioxide permeability of the gas separation membrane 3 is 1000 GPU or more, the concentration of carbon dioxide decreases sharply. Therefore, when the permeability is 1000 GPU or more, the significance of providing the first convex structure 5 becomes greater. Moreover, by providing the first convex structure 5, the gas separation device 1 that maximizes the use of the high permeability of the gas separation membrane 3 can be realized.

[0084] Figure 7 : is a graph showing the relationship between the flow rate of the mixed gas G1 and the concentration ratio of carbon dioxide in the gas separation membrane 3. In addition, the flow rate of the mixed gas G1 is the speed in the direction parallel to the first surface 31 of the gas separation membrane 3. In addition, 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.

[0085] As per Figure 7 It can be seen that when the first convex structure 5 is provided, the concentration ratio of carbon dioxide CO2 is improved compared to the case where the first convex structure 5 is not provided. In particular, it can be seen that the tendency becomes significant when the flow rate of the mixed gas G1 is low. Therefore, by providing the first convex structure 5, even when a fan is used to give the mixed gas G1 a flow rate, the power consumption of the fan can be suppressed and a sufficiently high concentration ratio can be achieved.

[0086] according to Figure 7 In the calculation example, it can be said that if the flow rate of the mixed gas G1 is greater than 0 m / s and less than 5 m / s, the significance of providing the first convex structure 5 becomes greater. Figure 7 The concentration ratio 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 carbon dioxide permeability of the gas separation membrane 3 is 10000 GPU.

[0087] 1.3. Exhaust pump

[0088] As the exhaust pump 6, for example, a dry pump such as a screw pump or a scroll pump, an oil rotary pump, a turbomolecular pump, etc. can be cited. Among them, a dry pump is preferably used, and a screw pump is more preferably used. Since these do not use oil or liquid, there is no concern about contaminating the internal space S1, and they have low power consumption, so they can be used as the exhaust pump 6.

[0089] 2. Second Implementation

[0090] Next, a gas separation membrane unit and a gas separation device according to a second embodiment will be described. Figure 8 It is a cross-sectional view showing the structure of a gas separation device 1 according to the second embodiment.

[0091] Hereinafter, the second embodiment will be described. However, in the following description, the differences from the first embodiment will be mainly described, and the description of the same matters will be omitted.

[0092] The second embodiment is the same as the first embodiment except that it further includes a mixed gas supply unit 7 .

[0093] like Figure 8 As shown, the gas separation device 1 according to the second embodiment includes, in addition to the above-mentioned gas separation membrane unit 2, a mixed gas supply unit 7. The mixed gas supply unit 7 includes a mixed gas flow path 72, a mixed gas introduction unit 74, and a mixed gas discharge unit 76.

[0094] The mixed gas flow path 72 is provided above and below the gas separation membrane unit 2, and is a flow path for the mixed gas G1 to flow, which is defined by the wall surface 33 including the first surface 31 of the gas separation membrane 3. Specifically, Figure 8 As shown, the mixed gas flow path portion 72 has: an upper plate 721, which is arranged at the uppermost part of the gas separation membrane unit 2; a lower plate 722, which is arranged at the lowermost part; and two side plates 723, which cover the side surfaces intersecting the X-axis. Moreover, the upper plate 721 and the lower plate 722 clamp the two gas separation membrane units 2, 2 along the Z-axis direction. In addition, the two side plates 723 clamp the two gas separation membrane units 2, 2 along the X-axis direction. Therefore, the first surface 31, the inner surface intersecting the X-axis, and the inner surface intersecting the Z-axis constitute the wall surface 33. In addition, in Figure 8 In the figure, only one side plate 723 is shown.

[0095] As each constituent material of the upper plate 721, the lower plate 722, and the side plate 723, for example, there can be cited resin materials, metal materials, ceramic materials, etc. In addition, a composite material containing these materials may be used.

[0096] in addition, Figure 8The mixed gas supply unit 7 shown has a second convex structure 8 protruding from the wall surface 33. Thus, the turbulent flow caused by the second convex structure 8 can also act on the mixed gas G1 present near the first surface 31. As a result, the reduction in the concentration of carbon dioxide CO2 on the first surface 31 can be further suppressed.

[0097] The second convex structure 8 has the same structure as the first convex structure 5 except for the different arrangement. The second convex structure 8 can be arranged on the wall surface 33, but is preferably arranged on the opposite surface of the first surface 31. Thus, the turbulence caused by the second convex structure 8 is easily exerted on the mixed gas G1 present near the first surface 31.

[0098] The mixed gas introduction unit 74 introduces the mixed gas G1 into the mixed gas flow path unit 72 . Figure 8 The mixed gas introduction unit 74 shown includes an air supply fan 742. The air supply fan 742 supplies the mixed gas G1 into the mixed gas flow path unit 72. Thus, a flow velocity can be imparted to the mixed gas G1 in the mixed gas flow path unit 72.

[0099] The mixed gas discharge unit 76 discharges the mixed gas G1' from the mixed gas flow path unit 72. The mixed gas G1' is a mixed gas after the carbon dioxide CO2 is separated by passing through the gas separation membrane unit 2. Figure 8 The mixed gas discharge section 76 shown has an exhaust fan 762. The exhaust fan 762 discharges the mixed gas G1' to the outside of the mixed gas flow path section 72. Thus, the mixed gas G1' with a low concentration of carbon dioxide CO2 can be quickly discharged, so that the reduction in the concentration of carbon dioxide CO2 on the first surface 31 of the gas separation membrane 3 can be more reliably suppressed.

[0100] In the second embodiment as described above, the same effect as in the first embodiment can be obtained. In addition, in the second embodiment, by providing the mixed gas flow path portion 72, when exhaust gas having a higher concentration of carbon dioxide CO2 than air is used as the mixed gas G1, the carbon dioxide CO2 can be separated while preventing the mixed gas G1 from being diluted by air. Therefore, even if the mixed gas G1 originally has a high concentration of carbon dioxide CO2, such as the mixed gas G1 containing a high concentration of carbon dioxide CO2 generated by various factories, etc., the reduction in separation efficiency can be suppressed.

[0101] 3. Effects achieved by the implementation method

[0102] As described above, the gas separation membrane unit 2 according to the embodiment includes a gas separation membrane 3, a gas flow path portion 4, and a first convex structure 5. The gas separation membrane 3 separates the carbon dioxide CO2 (predetermined gas component) contained in the mixed gas G1 supplied to the first surface 31 by passing through the second surface 32, which is the back side of the first surface 31. The gas flow path portion 4 includes a wall body 41 defining an internal space S1 for the flow of the separated gas containing carbon dioxide CO2. 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 body 41.

[0103] According to such a structure, the first convex structure 5 causes turbulence to the gas flow formed on the first surface 31 of the gas separation membrane 3, and even if the concentration of carbon dioxide CO2 in the mixed gas G1 on the first surface 31 is reduced due to the action of the gas separation membrane 3, new mixed gas G1 can be quickly and continuously supplied to 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 not easily reduced, and the gas separation membrane unit 2 in which the reduction in separation efficiency is suppressed can be obtained.

[0104] Furthermore, in the gas separation membrane unit 2 according to the above-described embodiment, two gas separation membranes 3 , 3 are provided, and the second surfaces 32 thereof are arranged to face each other.

[0105] According to such a configuration, carbon dioxide CO 2 can be separated on both sides (the upper side and the lower side) of the gas separation membrane unit 2 .

[0106] Furthermore, in the gas separation membrane unit 2 according to the above-described embodiment, the first convex structures 5 are respectively disposed on the first surfaces 31 of the two gas separation membranes 3 , 3 .

[0107] According to such a configuration, it is possible to suppress a decrease in the separation efficiency of carbon dioxide CO 2 in each gas separation membrane 3 .

[0108] In addition, it is preferable that the protrusion height of the first convex structures 5 is 0.1 mm or more and 50 mm or less.

[0109] If the height H is within the above range, appropriate turbulence can be generated without significantly impairing the flow rate of the mixed gas G1.

[0110] In addition, the carbon dioxide permeability of the gas separation membrane 3 is preferably 5000 GPU or more and 100000 GPU or less.

[0111] According to such a structure, it is possible to reduce the input amount of energy required for separation, and specifically, it is possible to realize a gas separation membrane 3 that can reduce the pressure difference between the first surface 31 side and the second surface 32 side. In addition, it is possible to realize a gas separation membrane unit 2 that can maximize the effect of the first convex structure 5 and facilitate the procurement and supply of the gas separation membrane 3.

[0112] 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 (predetermined gas component) flowing in the internal space S1 of the gas flow path unit 4.

[0113] According to such a structure, the internal space S1 can be decompressed to a pressure lower than the atmospheric pressure, so that a pressure difference is generated between the first surface 31 side and the second surface 32 side of the gas separation membrane 3. By utilizing this pressure difference, a gas separation device 1 that can separate carbon dioxide CO2 can be obtained. In addition, turbulence is caused by the first convex structure 5 relative to the airflow formed on the first surface 31 of the gas separation membrane 3, and even if the concentration of carbon dioxide CO2 in the mixed gas G1 on the first surface 31 is reduced due to the action of the gas separation membrane 3, new mixed gas G1 can be quickly and continuously supplied to the first surface 31. As a result, even if carbon dioxide CO2 passes through the gas separation membrane 3, it is not easy to reduce the concentration of carbon dioxide CO2 on the first surface 31, and the gas separation device 1 that suppresses the reduction of separation efficiency can be obtained.

[0114] In addition, the gas separation device 1 according to the embodiment includes a mixed gas supply unit 7. The mixed gas supply unit 7 includes a mixed gas flow path 72, a mixed gas introduction unit 74, and a mixed gas discharge unit 76. The mixed gas flow path 72 is defined by a wall surface 33 including the first surface 31, and is used for the mixed gas G1 to flow. The mixed gas introduction unit 74 introduces the mixed gas G1 into the mixed gas flow path 72. The mixed gas discharge unit 76 discharges the mixed gas G1' from the mixed gas flow path 72.

[0115] According to such a configuration, even when exhaust gas or the like having a higher carbon dioxide CO2 concentration than air is used as the mixed gas G1, the carbon dioxide CO2 can be separated while preventing the mixed gas G1 from being diluted by air.

[0116] Furthermore, in the gas separation device 1 according to the above-described embodiment, the mixed gas supply unit 7 includes the second convex structure 8 protruding from the wall surface 33 .

[0117] According to such a configuration, the turbulent flow caused by the second convex structures 8 can also act on the mixed gas G1 present near 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.

[0118] In the gas separation device 1 according to the above embodiment, the first convex structures 5 protrude from the outer surface 412 of the wall body 41 on the upstream side of the gas separation membrane 3 in the flow of the mixed gas G1 .

[0119] According to such a configuration, since the gas separation membrane 3 is located on the downstream side of the first convex structure 5, turbulence is easily caused on the first surface 31 of the gas separation membrane 3. This makes it easier to obtain the effect of suppressing the reduction in separation efficiency.

[0120] Furthermore, the gas separation device 1 according to the above-described embodiment includes at least two gas separation membrane units 2 that are arranged to be spaced apart from each other in the direction intersecting the first surface 31 .

[0121] With such a configuration, it is possible to realize a gas separation device 1 having a high separation efficiency of carbon dioxide CO 2 .

[0122] As mentioned above, the gas separation membrane unit and the gas separation device according to the present invention have been described based on the illustrated embodiments, but the present invention is not limited thereto.

[0123] For example, the gas separation membrane unit and the gas separation device according to the present invention may be devices in which the components of the above-described embodiments are replaced with arbitrary structures having the same functions, or may be devices in which arbitrary structures are added to the above-described embodiments.

Claims

1. A gas separation membrane unit, characterized in that: have: 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 a back surface of the first surface; a gas flow path portion having a wall defining an inner space for the separated predetermined gas component to flow; as well as A first convex structure protrudes from at least one of the first surface of the gas separation membrane and an outer surface of the wall body.

2. The gas separation membrane unit according to claim 1, characterized in that: Two gas separation membranes are provided, and the second surfaces of the two gas separation membranes are arranged to face each other.

3. The gas separation membrane unit according to claim 2, characterized in that: The first convex structures are respectively arranged on the first surfaces of the two gas separation membranes.

4. The gas separation membrane unit according to any one of claims 1 to 3, characterized in that: The protrusion height of the first convex structure is greater than or equal to 0.1 mm and less than or equal to 50 mm.

5. The gas separation membrane unit according to any one of claims 1 to 3, characterized in that: The gas separation membrane has a carbon dioxide permeability of 5,000 GPU or more and 100,000 GPU or less.

6. A gas separation device, characterized in that: have: The gas separation membrane unit according to any one of claims 1 to 3; and An exhaust pump exhausts the predetermined gas component flowing in the internal space of the gas flow path portion.

7. The gas separation device according to claim 6, characterized in that: It also has a mixed gas supply unit. The mixed gas supply unit comprises: a mixed gas flow path portion, the mixed gas flow path portion being defined by a wall surface including the first surface and used for the mixed gas to flow; a mixed gas introduction portion for introducing the mixed gas into the mixed gas flow path portion; and A mixed gas discharge portion discharges the mixed gas from the mixed gas flow path portion.

8. The gas separation device according to claim 7, characterized in that: The mixed gas supply unit includes a second convex structure protruding from the wall surface.

9. The gas separation device according to claim 7, characterized in that: The first convex structure protrudes from the outer surface of the wall body on the upstream side of the gas separation membrane in the flow of the mixed gas.

10. The gas separation device according to claim 6, characterized in that: At least two of the gas separation membrane units are provided, and the two gas separation membrane units are arranged to be separated from each other in a direction intersecting the first surface.

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