Separation apparatus and design method for separation apparatus

Abstract

The present invention provides a separation apparatus and a method for designing a separation apparatus that have a good selectivity ratio relative to the selectivity ratio of the separation membrane. [Solution] A separation device for selectively separating carbon dioxide gas from a supply gas, comprising: a separation membrane that selectively permeates the carbon dioxide gas contained in the supply gas; a containment section having a containment space for containing the permeate gas that has permeated through the separation membrane; piping connected to the containment section; and a pump that depressurizes the containment space via the piping and sucks out the permeate gas, wherein when the carbon dioxide gas permeability of the separation membrane is A, the nitrogen gas permeability of the separation membrane is B, the total pressure of the supply gas is P1, and the total pressure of the permeate gas in the containment space is P2, then (P1 / P2) / (A / B)≧1, and when the gas permeability of the permeate gas through the flow path between the separation membrane and the pump is C, then 1>(B+C) / (A+C)≧0.8.

Description

Technical Field

[0001] The present invention relates to a separation device and a method for designing a separation device.

Background Art

[0002] In order to achieve carbon neutrality, technologies for capturing and recovering carbon dioxide gas in the atmosphere have been studied. As one such technology, a membrane separation method using a separation membrane to separate a target gas such as carbon dioxide gas from a mixed gas such as air is known.

[0003] For example, Patent Document 1 discloses a separation membrane including a porous support, a thin film of a siloxane compound disposed on the porous support and having a surface layer plasma-treated with a non-polymerizable gas, and a plasma polymerization membrane disposed on the thin film. The porous support supports the thin film and the polymerization membrane. The mixed gas is supplied to the thin film and the polymerization membrane. In the thin film and the polymerization membrane, the permeability of the target gas in the mixed gas is higher than the permeability of the non-target gas in the mixed gas. Therefore, the separation membrane can selectively separate the target gas from the mixed gas.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Separation membranes are used, for example, by being incorporated into separation devices. A separation device includes, for example, a containment section for containing the gas that has permeated through the separation membrane, and a pump that reduces the pressure inside the containment section and sucks out the gas that has permeated through the separation membrane. The ratio of the permeability of the target gas to the permeability of the non-target gas through the separation membrane is called the "selectivity ratio." Even if a separation membrane with a good selectivity ratio is incorporated into a separation device, depending on the configuration of parts of the separation device other than the separation membrane, the selectivity ratio of the separation device may be significantly lower than that of the separation membrane. [Means for solving the problem]

[0006] A separation apparatus according to an application example of the present invention is a separation apparatus that selectively separates carbon dioxide gas from a supply gas containing carbon dioxide gas and nitrogen gas, A separation membrane comprising a porous body and a resin layer disposed on the porous body, which selectively permeates the carbon dioxide gas contained in the supply gas toward the porous body, A containment section is formed which holds the separation membrane and contains a containment space for containing the permeate gas that has permeated through the separation membrane, The piping connected to the aforementioned housing section, A pump that reduces the pressure in the containment space via the aforementioned piping and sucks out the permeate gas, Equipped with, When the carbon dioxide gas permeability of the separation membrane is A, 500,000 GPU ≥ A ≥ 1,000 GPU And, When the nitrogen gas permeability of the separation membrane is B, the total pressure of the supply gas is P1, and the total pressure of the permeate gas in the containment space is P2, (P1 / P2) / (A / B)≧1 And, The flow path of the permeate gas between the separation membrane and the pump includes the containment space and the internal space of the piping. When the gas permeability of the aforementioned flow path is C, 1 > (B + C) / (A + C) ≥ 0.8 That is the case.

[0007] A separation apparatus design method according to an application example of the present invention is a separation apparatus design method for selectively separating carbon dioxide gas from a supply gas containing carbon dioxide gas and nitrogen gas, A step of selecting a separation membrane comprising a porous body and a resin layer disposed on the porous body, which is permeable to the carbon dioxide gas contained in the supply gas toward the porous body, A process of designing a housing section that holds the separation membrane and has a housing space formed for housing the permeate gas that has permeated through the separation membrane, piping connected to the housing section, and a pump that depressurizes the housing space via the piping and sucks out the permeate gas, Equipped with, The flow path of the permeate gas between the separation membrane and the pump includes the containment space and the internal space of the piping. In the aforementioned selection process, When the carbon dioxide gas permeability of the separation membrane is A, select the separation membrane such that 500,000 GPU ≥ A ≥ 1,000 GPU. In the aforementioned design process, When the nitrogen gas permeability of the separation membrane is B, the total pressure of the supply gas is P1, and the total pressure of the permeate gas in the containment space is P2, a pump capable of reducing the pressure in the containment space is selected such that (P1 / P2) / (A / B) ≥ 1. When the gas permeability of the aforementioned flow path is C, the flow path is designed such that 1 > (B + C) / (A + C) ≥ 0.8. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view showing a separation device according to the first embodiment. [Figure 2] This is a cross-sectional view showing a separation device according to the first embodiment. [Figure 3] This is a cross-sectional view showing an enlarged portion of Figure 2. [Figure 4] This is a schematic diagram illustrating a method for measuring the gas permeability of a flow path in the first embodiment. [Figure 5] This is a flowchart showing a design method for a separation apparatus according to the first embodiment. [Figure 6] It is a cross-sectional view showing the separation device according to the second embodiment. [Figure 7] It is a schematic view showing a method for measuring the gas permeability of the flow path in the second embodiment. [Figure 8] It is a cross-sectional view showing the separation membrane according to Modification 1. [Figure 9] It is a cross-sectional view showing the separation membrane according to Modification 2. [Figure 10] It is a cross-sectional view showing the separation membrane according to Modification 3. [Figure 11] It is a cross-sectional view showing the separation device according to Comparative Example 1. [Figure 12] Table 1 shows the configurations and evaluation results of the separation devices of Examples 1 to 3 and the separation devices of Comparative Examples 1 to 3.

Mode for Carrying Out the Invention

[0009] Hereinafter, a plurality of embodiments and a plurality of modifications of the present invention will be described with reference to the drawings. Note that the following description does not limit the technical scope and the meaning of terms described in the claims. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0010] <First Embodiment> First, the separation device 100 according to the first embodiment will be described. FIG. 1 is a perspective view showing the separation device 100 according to the present embodiment. FIG. 2 is a cross-sectional view showing the separation device 100 according to the present embodiment. FIG. 3 is a cross-sectional view showing an enlarged part of FIG. 2.

[0011] In FIG. 1, the pump 160 described later is schematically shown as a cylindrical shape. Similarly, in FIG. 2, the pump 160 is schematically shown as a circle. Also, in FIG. 2, the housing portion 130 and the pipe 150 described later are shown by end faces instead of cross-sections.

[0012] In the figures of this embodiment, the X, Y, and Z axes are defined as three mutually orthogonal axes. Each axis is represented by an arrow, with the tip of the arrow being "positive" and the base of the arrow being "negative". In the following description, for example, "X-axis direction" includes both the positive and negative directions of the X axis. The same applies to the Y-axis and Z-axis directions. In the following description, the positive side of the Z axis is referred to as "up," and the negative side of the Z axis is referred to as "down." The Z axis does not need to be parallel to the vertical axis and may intersect the vertical axis. In the following, the uppermost end of each member is referred to as the "upper end," and a certain range extending downward from the upper end of the member is referred to as the "upper end portion." Similarly, the lowermost end of each member is referred to as the "lower end," and a certain range extending upward from the lower end of the member is referred to as the "lower end portion."

[0013] The separation device 100, as outlined with reference to Figures 1 and 2, comprises a separation membrane 110, a housing 130, piping 150, and a pump 160.

[0014] The surface of the separation membrane 110 includes a first surface 110a and a second surface 110b, which form a front and back surface. A mixed gas is supplied to the first surface 110a of the separation membrane 110. Hereinafter, the mixed gas supplied to the separation membrane 110 will also be referred to as "supply gas G1". Supply gas G1 contains carbon dioxide gas and nitrogen gas. Supply gas G1 is not particularly limited, but for example, it could be air. In the separation membrane 110, the permeability of carbon dioxide gas is higher than that of nitrogen gas. Therefore, the separation membrane 110 can selectively permeate the carbon dioxide gas contained in supply gas G1. As a result, the separation membrane 110 can selectively separate carbon dioxide gas from supply gas G1. Here, "selectively permeating or separating carbon dioxide gas" does not mean that only carbon dioxide gas is permeated or separated, and nitrogen gas is not permeated or separated at all. "Selectively permeating or separating carbon dioxide gas" means that carbon dioxide gas is permeated or separated with a higher permeability than nitrogen gas, that is, carbon dioxide gas is permeated or separated preferentially over nitrogen gas.

[0015] The containment section 130 holds the separation membrane 110. The containment section 130 has a containment space 130s formed therein for containing the gas that has permeated through the separation membrane 110. The second surface 110b of the separation membrane 110 faces the containment space 130s. Hereinafter, the gas that has permeated through the separation membrane 110 will also be called "permeate gas G2". The separation membrane 110 permeates carbon dioxide gas preferentially, while also permeating nitrogen gas. Therefore, permeate gas G2 contains both carbon dioxide gas and nitrogen gas.

[0016] The piping 150 is connected to the containment section 130. The pump 160 reduces the pressure in the containment space 130s via the piping 150. This causes the pressure on the first surface 110a of the separation membrane 110 to be higher than the pressure on the second surface 110b. As a result, the permeation of carbon dioxide gas through the separation membrane 110 is promoted. The permeated gas G2 in the containment space 130s is drawn into the pump 160 and recovered.

[0017] In this embodiment, the separation device 100 further comprises a perforated plate 120 that supports the separation membrane 110, and a fixing member 140 that fixes the separation membrane 110 and the perforated plate 120 to the housing section 130. The parts of the separation device 100 will be described in detail below.

[0018] First, let me explain the separation membrane 110. As shown in Figure 3, the separation membrane 110 comprises a porous body 111 and a resin layer 112 disposed on the porous body 111.

[0019] In this embodiment, the porous body 111 consists of a porous layer 113 in which a plurality of pores 113h are formed. The porous layer 113 extends in the X-axis direction and the Y-axis direction. In this embodiment, the shape of the porous layer 113 in a top view is circular. However, the shape of the porous layer in a top view is not limited to the above, and may be a polygon such as a square. The lower surface of the porous layer 113 corresponds to the second surface 110b of the separation membrane 110.

[0020] Each void 113h penetrates the porous layer 113 in the thickness direction. In this embodiment, the thickness direction of the porous layer 113 coincides with the Z-axis direction. Multiple voids 113h are formed to be dispersed on the XY plane. Here, the diameter of the inscribed circle of a void 113h is defined as the "diameter" of the void 113h. In this embodiment, the diameter of each void 113h is generally constant and does not change in the thickness direction.

[0021] The average value of the diameters at the upper ends of multiple pores 113h is defined as the "average diameter" of the pores 113h. The average diameter of the pores 113h is preferably between 0.01 μm and 1000 μm, more preferably between 0.1 μm and 500 μm, and even more preferably between 0.5 μm and 300 μm. The average diameter of the pores 113h can be measured using a through-pore diameter evaluation device after removing the resin layer 112 from the separation membrane 110 to obtain a single porous layer 113. An example of a through-pore diameter evaluation device is a palm porometer manufactured by PMI. By setting the average diameter of the pores 113h to be above the lower limit, the carbon dioxide gas permeability of the porous layer 113 can be improved. Furthermore, by setting the average diameter of the pores 113h to be below the upper limit, the mechanical strength of the separation membrane 110 can be improved.

[0022] The average thickness of the porous layer 113 at multiple locations on the XY plane is defined as the "average thickness" of the porous layer 113. The average thickness of the porous layer 113 is not particularly limited, but is preferably 1 μm or more and 3000 μm or less, more preferably 5 μm or more and 500 μm or less, and even more preferably 10 μm or more and 150 μm or less. The average thickness of the porous layer 113 can be measured, for example, by a scanning electron microscope (SEM). By setting the average thickness of the porous layer 113 to be above the lower limit, the mechanical strength of the separation membrane 110 can be improved. By setting the average thickness of the porous body 111 to be below the upper limit, the carbon dioxide gas permeability of the separation membrane 110 can be improved.

[0023] The material of the porous body 111 is, for example, a polymer material, a ceramic material, or a metallic material. Examples of polymer materials include polyolefin resins such as polyethylene and polypropylene, fluororesins such as polytetrafluoroethylene, polyvinyl fluoride and polyvinylidene fluoride, polystyrene, cellulose, cellulose acetate, polyurethane, polyacrylonitrile, polyphenylene oxide, polysulfone, polyethersulfone, polyimide, polyaramid, and nylon. Examples of ceramic materials include alumina, cordierite, mullite, silicon carbide, and zirconia. Examples of metallic materials include stainless steel.

[0024] However, the structure of the porous body is not limited to the above. For example, as will be described later, the diameter of the pores formed in the porous body may vary in the thickness direction. Also, the porous body may be composed of multiple stacked porous layers.

[0025] The resin layer 112 is a substantially dense film and has good affinity for carbon dioxide molecules. Therefore, the carbon dioxide gas permeability in the resin layer 112 is higher than that of nitrogen gas permeability. As a result, the resin layer 112 selectively permeates carbon dioxide gas in the supply gas G1. In this embodiment, the resin layer 112 covers almost the entire upper surface of the porous body 111. Therefore, the shape of the resin layer 112 in a top view is circular, similar to that of the porous body 111 in this embodiment. However, the shape of the resin layer in a top view is not limited to the above and may be a polygon such as a square. The upper surface of the resin layer 112 corresponds to the first surface 110a of the separation membrane 110.

[0026] The average thickness of the resin layer 112 at multiple locations on the XY plane is defined as the "average thickness" of the resin layer 112. In this embodiment, the average thickness of the resin layer 112 is smaller than the average thickness of the porous body 111. The average thickness of the resin layer 112 is not particularly limited, but is preferably 10 nm to 1000 nm, more preferably 10 nm to 800 nm, and even more preferably 30 nm to 500 nm. The average thickness of the resin layer 112 can also be measured, for example, by SEM. By setting the average thickness of the resin layer 112 to be above the lower limit, defects and damage to the resin layer 112 can be suppressed. By setting the average thickness of the resin layer 112 to be below the upper limit, the carbon dioxide gas permeability of the separation membrane 110 can be improved.

[0027] The material of the resin layer 112 is a polymer material. Examples of polymer materials include polyolefin resins such as polyethylene and polypropylene, fluororesins such as polytetrafluoroethylene, polyvinyl fluoride and polyvinylidene fluoride, polystyrene, cellulose, cellulose acetate, polyurethane, polyacrylonitrile, polyphenylene oxide, polysulfone, polyethersulfone, polyimide, polyaramid, organopolysiloxane, polyethylene terephthalate (PET), polyacetal (POM), and polylactic acid (PLA). The constituent material of the resin layer 112 may be a composite material of one or more of these polymer materials. Furthermore, the polymer material may be a thermoplastic resin, a thermosetting resin, or a photocurable resin.

[0028] Of these, it is preferable to use organopolysiloxane as the constituent material of the resin layer 112. Organopolysiloxane has a good affinity for carbon dioxide molecules.

[0029] Next, we will describe the perforated plate 120. In this embodiment, the perforated plate 120 is a flat plate that is generally parallel to the XY plane. The shape of the perforated plate 120 when viewed from above is, for example, circular. The separation membrane 110 is placed on the perforated plate 120. Multiple through holes 121 are formed in the perforated plate 120. Each through hole 121 penetrates the perforated plate 120 in the thickness direction. In this embodiment, the thickness direction of the perforated plate 120 coincides with the Z-axis direction. The multiple through holes 121 are formed to be distributed on the XY plane.

[0030] The rigidity of the perforated plate 120 is higher than that of the separation membrane 110. Therefore, the perforated plate 120 can support the separation membrane 110 well. As a result, deformation and damage of the separation membrane 110 can be suppressed when there is a difference in pressure between the first surface 110a and the second surface 110b of the separation membrane 110.

[0031] The shape of each through-hole 121 in a top view is, for example, a circle or a polygon such as a hexagon. The diameter of the inscribed circle of each through-hole 121 is defined as the "diameter" of each through-hole 121. The diameter of each through-hole 121 is generally constant and does not change in the thickness direction of the perforated plate 120. The average value of the diameters of multiple through-holes 121 is defined as the "average diameter" of the through-holes 121. In this embodiment, the average diameter of the through-holes 121 of the perforated plate 120 is larger than the average diameter of the pores 113h of the porous body 111. This allows for good gas permeability of the perforated plate 120.

[0032] The average diameter of the through-holes 121 is not particularly limited, but is preferably 0.1 mm or more and 10 mm or less, more preferably 0.5 mm or more and 5 mm or less, and even more preferably 0.7 mm or more and 3 mm or less. By setting the average diameter of the through-holes 121 to be above the lower limit, the gas permeability of the porous plate 120 can be improved. By setting the average diameter of the through-holes 121 to be below the upper limit, the rigidity of the porous plate 120 can be improved. Furthermore, by setting the average diameter of the through-holes 121 to be below the upper limit, it is possible to suppress the bending of the separation membrane 110 so that it falls into the through-holes 121 when there is a difference between the pressure applied to the first surface 110a and the pressure applied to the second surface 110b of the separation membrane 110.

[0033] The average thickness of the perforated plate 120 at multiple locations on the XY plane is defined as the "average thickness" of the perforated plate 120. In this embodiment, the average thickness of the perforated plate 120 is greater than the average thickness of the separation membrane 110. The average thickness of the perforated plate 120 is not particularly limited, but is preferably 0.01 mm or more and 50 mm or less, more preferably 0.05 mm or more and 30 mm or less, and even more preferably 0.1 mm or more and 5 mm or less. By setting the average thickness of the perforated plate 120 to be above the lower limit, deformation of the perforated plate 120 can be suppressed when the pump 160 is depressurizing the containment space 130s. Furthermore, by setting the average thickness of the perforated plate 120 to be below the upper limit, pressure loss when the permeate gas G2 flows through each through-hole 121 of the perforated plate 120 can be reduced.

[0034] The material of the perforated plate 120 is a ceramic material or a metallic material, etc. Examples of ceramic materials include alumina. Examples of metallic materials include stainless steel, titanium, and aluminum. The configuration of the perforated plate is not limited to the above. Furthermore, the separation device does not necessarily need to have a perforated plate.

[0035] Next, the storage section 130 will be described. As shown in Figures 1 and 2, the housing section 130 is a chamber. In this embodiment, the housing section 130 is a hollow cylindrical shape. The central axis C1 of the housing section 130 extends in the Z-axis direction. The housing section 130 has an inlet 130a through which the permeate gas G2 flows in, and an outlet 130b through which the permeate gas G2 flows out.

[0036] Specifically, the containment section 130 comprises a first wall section 131 with an intake port 130a, a second wall section 132 located below the first wall section 131 with an outlet port 130b, and a side wall section 133 located between the first wall section 131 and the second wall section 132. The first wall section 131 and the second wall section 132 are flat plates generally parallel to the XY plane. The top view of the first wall section 131 and the second wall section 132 is circular. The side wall section 133 is cylindrical and extends in the Z-axis direction. The upper end of the side wall section 133 is connected to the outer circumference of the first wall section 131 over its entire circumference. The lower end of the side wall section 133 is connected to the outer circumference of the second wall section 132 over its entire circumference.

[0037] The storage space 130s is the internal space of the storage section 130 formed by the first wall portion 131, the second wall portion 132, and the side wall portion 133. In this embodiment, the shape of the storage space 130s is cylindrical.

[0038] The intake opening 130a penetrates the first wall portion 131 in the thickness direction, approximately through its center in a top view. The shape of the intake opening 130a in a top view is, for example, circular. On the upper surface of the first wall portion 131, a step 130c is formed around the intake opening 130a, on which the perforated plate 120 can be placed. The perforated plate 120 is positioned on the step 130c so as to cover the intake opening 130a.

[0039] The outlet 130b penetrates the second wall portion 132 in the thickness direction, approximately through its center in a top view. The shape of the outlet 130b in a top view is generally similar to the outer shape of the piping 150, which will be described later, and is circular.

[0040] However, the specific shape of the containment section is not limited to the above. For example, the shape of the containment section may be a hollow rectangular parallelepiped. Also, for example, it is not necessary to form a step in the first wall for arranging the perforated plate. Furthermore, the shapes of the intake port, containment space, and outlet port are not limited to the above. For example, the shape of the intake port and outlet port in a top view may be a polygon such as a square. Also, for example, the shape of the containment space may be a rectangular parallelepiped. Furthermore, the positions of the intake port and outlet port are not limited to the above, as long as the permeate gas can flow into the containment space and the permeate gas that has flowed into the containment space can be discharged into the piping.

[0041] Next, the fixing member 140 will be described. As shown in Figures 1 and 2, the shape of the fixing member 140 in this embodiment is frame-shaped. The fixing member 140 covers the outer periphery of the separation membrane 110 and the perforated plate 120 from above and is fixed to the housing 130 by a plurality of fasteners 141 such as screws and bolts. In this way, the housing 130 holds the separation membrane 110 and the perforated plate 120. At this time, although not shown in the figures, it is preferable to arrange a sealing member to prevent gas leakage from the gap between the separation membrane 110 and the fixing member 140, and the gap between the fixing member 140 and the housing 130. However, the specific shape of the fixing member is not limited to the above as long as it can fix the separation membrane to the housing. Furthermore, the method of fixing the separation membrane and the perforated plate to the housing is not limited to the method using a fixing member.

[0042] Next, I will explain piping 150. The pipe 150 is cylindrical and, in this embodiment, extends linearly in the Z-axis direction. Therefore, the internal space 151 of the pipe 150 also extends linearly in the Z-axis direction. The upper end of the pipe 150 is inserted into the outlet 130b, and the upper end of the pipe 150 is approximately flush with the upper surface of the second wall 132 of the housing section 130. The internal space 151 of the pipe 150 communicates with the housing section 130s. The diameter D1 of the upper end of the internal space 151 gradually decreases from upstream to downstream.

[0043] However, the specific shape of the piping is not limited to the above. For example, the piping may be bent. Also, the diameter of the upper end of the piping may remain constant from upstream to downstream. Furthermore, instead of inserting the upper end of the piping into the outlet, the piping may be connected to the outlet of the second wall of the housing such that the upper end of the piping is in contact with the lower surface of the second wall of the housing.

[0044] The arithmetic mean roughness of the forming surface of the through-holes 121 of the perforated plate 120, the housing section 130, and the inner surface of the piping 150 is defined as "surface roughness." The surface roughness is not particularly limited, but is preferably 0.012 μm or more and 6.3 μm or less, more preferably 0.05 μm or more and 6.3 μm or less, and even more preferably 0.1 μm or more and 1.6 μm or less. By setting the surface roughness to be below the above upper limit, the pressure loss when the permeate gas G2 flows through the multiple through-holes 121, the housing space 130s, and the internal space 151 can be reduced. By setting the surface roughness to be above the above lower limit, the manufacturing costs of the perforated plate 120, the housing section 130, and the piping 150 can be reduced. The surface roughness is measured using a contact-type or non-contact-type surface roughness measuring instrument in accordance with the provisions of JIS B 0601:2013.

[0045] Next, I will explain pump 160. Pump 160 is connected to the lower end of piping 150. Pump 160 reduces the pressure in the containment space 130s via piping 150. Pump 160 is, for example, a dry vacuum pump. However, the type of pump is not particularly limited as long as it can reduce the pressure in the containment space to a desired pressure, as will be described later.

[0046] Next, we will explain the flow of supply gas G1 and permeate gas G2. First, as shown in Figure 2, the supply gas G1 is supplied to the first surface 110a of the separation membrane 110. When the containment space 130s is depressurized by the pump 160, some of the carbon dioxide and nitrogen gas in the supply gas G1 permeates through the separation membrane 110. The permeate gas G2, which contains the carbon dioxide and nitrogen gas that has permeated through the separation membrane 110, permeates through the multiple through-holes 121 of the perforated plate 120. Next, the permeate gas G2 flows into the internal space 151 of the piping 150 via the containment space 130s. Then, the permeate gas G2 is sucked into the pump 160 and recovered.

[0047] Therefore, in this embodiment, the flow path FP between the separation membrane 110 of permeate gas G2 and the pump 160 is composed of multiple through holes 121 in the perforated plate 120, the containment space 130s, and the internal space 151 of the piping 150.

[0048] In this embodiment, the flow path FP, which connects the separation membrane 110 to the containment space 130s of the containment section 130 and the internal space 151 of the piping 150, is configured in a straight line. That is, when the pump 160 is removed from the separation device 100 and the internal space 151 of the piping 150 is viewed from below, the perforated plate 120 and the separation membrane 110 can be seen. Because the flow path FP is straight in this way, the pressure loss when the permeate gas G2 flows through the flow path FP can be reduced.

[0049] Furthermore, in this embodiment, when viewed from above, the center of the separation membrane 110, the center of the porous plate 120, the central axis C1 of the containment space 130s, and the center of the internal space 151 of the piping 150 are located in approximately the same position. Therefore, compared to the case where the positions of these centers are offset from each other, the pressure loss when the permeate gas G2 flows through the flow path FP can be reduced.

[0050] Furthermore, in this embodiment, the upper end of the internal space 151 is the portion in the flow path FP where the permeate gas G2 flows from the containment section 130 into the pipe 150. Hereinafter, the upper end of the internal space 151 will also be referred to as the "inlet section FP11" of the flow path FP. As mentioned above, the diameter D1 of the inlet section FP11 gradually decreases from upstream to downstream. This causes the permeate gas G2 to gradually constrict as it flows from the containment section 130 into the pipe 150. Therefore, the pressure loss when the permeate gas G2 flows from the containment section 130 into the pipe 150 can be reduced. Note that if the tip of the pipe is positioned to be in contact with the lower surface of the second wall of the containment section, the outlet of the containment section corresponds to the inlet section. In this case, a similar effect can be obtained by gradually decreasing the diameter of the outlet from upstream to downstream. However, the diameter of the inlet section may be approximately constant from upstream to downstream.

[0051] Next, the parameters of the separation device 100 will be described. Let A be the carbon dioxide gas permeability of the separation membrane 110. Let B be the nitrogen gas permeability of the separation membrane 110. "Permeability" refers to the amount of gas permeating per unit area, unit time, and unit pressure. The carbon dioxide gas permeability A and the nitrogen gas permeability B are measured using a gas permeability measuring device in accordance with the gas permeability test method (Part 1: Differential pressure method) specified in JIS K 7126-1:2006. Examples of gas permeability measuring devices include the GTR-11A / 31A manufactured by GTR Tech Co., Ltd. The units for carbon dioxide gas permeability A and nitrogen gas permeability B are, for example, GPU. Note that 1 GPU is equal to 3.35 × 10⁻¹⁶ -10 mol·m -2 ·s -1 ·Pa -1 Thus, the carbon dioxide gas permeability A and the nitrogen gas permeability B of the separation membrane 110 represent the performance of the separation membrane 110 alone, without being incorporated into the separation device 100.

[0052] In this embodiment, 500,000 GPU ≥ A ≥ 1,000 GPU. More preferably, 400,000 GPU ≥ A ≥ 5,000 GPU, and even more preferably, 300,000 GPU ≥ A ≥ 7,000 GPU. By setting the carbon dioxide gas permeability A to be above the above lower limit, the amount of energy required for separation can be reduced. Specifically, the amount of energy required for separation is the difference between the pressure applied to the first surface 110a and the pressure applied to the second surface 110b of the separation membrane 110. Furthermore, in the separation membrane 110 which includes a resin layer 112 made of polymer material, there is a trade-off relationship between the carbon dioxide gas permeability A and the selectivity ratio of the separation membrane 110. Therefore, if the carbon dioxide gas permeability A exceeds the above upper limit, it may become difficult to maintain a balance with the selectivity ratio of the separation membrane 110.

[0053] The carbon dioxide gas permeability A of the separation membrane 110 can be controlled by adjusting the material of the resin layer 112, the average diameter of the pores 113h of the porous body 111, and the average thickness of the porous body 111. Specifically, the carbon dioxide gas permeability A of the separation membrane 110 can be increased by using a material with high affinity for carbon dioxide molecules for the resin layer 112. The carbon dioxide gas permeability A of the separation membrane 110 can also be increased by using a material with high gas permeability for the porous body 111. Furthermore, the carbon dioxide gas permeability A of the separation membrane 110 can be increased by increasing the average diameter of the pores 113h of the porous body 111. In addition, the carbon dioxide gas permeability A of the separation membrane 110 can be increased by decreasing the average thickness of the porous body 111. The inventors of this application have confirmed that by configuring the material of the resin layer 112, the average diameter of the pores 113h of the porous body 111, and the average thickness of the porous body 111 as described in the description of the separation membrane 110, a separation membrane 110 with a GPU of 500,000 ≥ A ≥ 1,000 GPU can be realized.

[0054] As shown in (Equation 1) below, the ratio of carbon dioxide gas permeability A to nitrogen gas permeability B is defined as the selectivity ratio of the separation membrane 110. Selectivity ratio of separation membrane 110 = A / B (Equation 1)

[0055] Hereafter, the selectivity of the separation membrane 110 will also be referred to as "selectivity ratio A / B". The carbon dioxide gas permeability A is greater than the nitrogen gas permeability B. Therefore, the selectivity ratio A / B of the separation membrane 110 is greater than 1.

[0056] Incidentally, after diligent investigation by the inventors of this application, it was found that even if a separation membrane 110 having a good selectivity ratio A / B is incorporated into the separation device 100, the selectivity ratio of the separation device 100 will decrease significantly compared to the selectivity ratio A / B of the separation membrane 110, depending on the amount of pressure reduction of the pump 160. The reason for this estimation is explained below.

[0057] Let p1 be the partial pressure of carbon dioxide gas in the supply gas G1. Let p2 be the partial pressure of carbon dioxide gas in the permeate gas G2 in the containment space 130s. In this case, it is considered that carbon dioxide gas permeates through the separation membrane 110 when the following equation (Equation 2) is satisfied. p1>p2 (Formula 2)

[0058] Here, let P1 be the total pressure of the supply gas G1, and P2 be the total pressure of the permeate gas G2 in the containment space 130s. Also, let c1 be the concentration of carbon dioxide gas in the supply gas G1, and c2 be the concentration of carbon dioxide gas in the permeate gas G2 in the containment space 130s. In this case, since p1 = P1·c1 and p2 = P2·c2, equation (2) can be transformed into equation (3) below.

[0059] P1·c1>P2·c2 (Formula 3) Further transformation of (Equation 3) yields the following (Equation 4). (P1 / P2)>(c2 / c1) (Formula 4)

[0060] c2 / c1 is the ratio of the concentration c2 of carbon dioxide gas that has permeated through the separation membrane 110 to the concentration c1 of carbon dioxide gas supplied to the separation membrane 110. Therefore, below, c2 / c1 will also be referred to as the "concentration ratio c2 / c1". A higher concentration ratio c2 / c1 means that the amount of carbon dioxide gas recovered by the separation device 100 is greater. Furthermore, from the above (Equation 4), it can be seen that the concentration ratio c2 / c1 is smaller than the ratio of the total pressure P1 of the supply gas G1 to the total pressure P2 of the permeate gas G2. Hereafter, P1 / P2 will also be referred to as the "total pressure ratio P1 / P2".

[0061] Furthermore, theoretically, the concentration ratio c2 / c1 will be smaller than the selectivity ratio A / B. Therefore, if the total pressure ratio P1 / P2 is smaller than the selectivity ratio A / B of the separation membrane 110, the upper limit of the concentration ratio c2 / c1 will be even lower than the selectivity ratio A / B of the separation membrane 110 selected when incorporated into the separation device 100 (total pressure ratio P1 / P2). On the other hand, if the total pressure ratio P1 / P2 is greater than or equal to the selectivity ratio A / B of the separation membrane 110, the upper limit of the concentration ratio c2 / c1 will be equal to the selectivity ratio A / B of the separation membrane 110 selected when incorporated into the separation device 100. In other words, the concentration ratio c2 / c1 can be increased more when the total pressure ratio P1 / P2 is greater than or equal to the selectivity ratio A / B of the separation membrane 110 than when the total pressure ratio P1 / P2 is smaller than the selectivity ratio A / B of the separation membrane 110.

[0062] Therefore, it is considered that the concentration ratio c2 / c1 of the separation device 100 can be increased if the following (Equation 5) is satisfied.

[0063] (P1 / P2)≧(A / B) (Formula 5) By transforming (Equation 5), we obtain the following (Equation 6). (P1 / P2) / (A / B)≧1 (Formula 6)

[0064] The total pressure ratio P1 / P2 can be controlled by adjusting the amount of pressure reduction by the pump 160. Specifically, the more the pump 160 reduces the pressure in the containment space 130s, the lower the total pressure P2 becomes, and the larger the total pressure ratio P1 / P2 becomes.

[0065] However, the larger the total pressure ratio P1 / P2, the more energy is required to drive the pump 160. Also, the larger the total pressure ratio P1 / P2, the greater the difference between the pressure applied to the first surface 110a and the pressure applied to the second surface 110b of the separation membrane 110. As a result, the period until the separation membrane 110 is damaged by repeated or continuous pressure application, i.e., the lifespan of the separation membrane 110, is shortened. Therefore, although not particularly limited, it is preferable that 15 ≥ (P1 / P2) / (A / B).

[0066] Here, the method for measuring the total pressures P1 and P2 will be described. As shown in Figure 2, for example, a pressure gauge PS1, such as a barometer, is placed outside the separation device 100 and around the separation membrane 110. Also, for example, a pressure gauge PS2, such as a gauge pressure gauge, is placed in a through-hole formed in the housing section 130. The total pressure P1 of the supply gas G1 can be obtained as absolute pressure by pressure gauge PS1. The total pressure P2 of the permeate gas G2 can be obtained as the sum (absolute pressure) of the gauge pressure measured by pressure gauge PS2 and atmospheric pressure. However, the type of pressure gauge used to measure the total pressure P1 of the supply gas G1 and the total pressure P2 of the permeate gas G2 is not particularly limited as long as the total pressures P1 and P2 can ultimately be obtained as absolute pressures.

[0067] As explained above, depending on the amount of pressure reduced by pump 160, equation (6) may not be satisfied, and the concentration ratio c2 / c1 may decrease significantly. A decrease in the concentration ratio c2 / c1 means that the permeability of carbon dioxide gas through the separation device 100 decreases. Therefore, it is thought that there were cases where the selectivity ratio of the separation device 100 decreased significantly compared to the selectivity ratio A / B of the separation membrane 110.

[0068] However, further investigation by the inventors of the present invention revealed that even when the separation device 100 is configured to satisfy (Equation 6), there are still cases where the selectivity ratio of the separation device 100 is significantly lower than the selectivity ratio A / B of the separation membrane 110. This is thought to be because configuring the separation device 100 to satisfy (Equation 6) increases the flow rate and velocity of the permeate gas G2, increasing the pressure loss in the flow path FP between the separation membrane 110 and the pump 160, making it more difficult for the permeate gas G2 to flow. Therefore, the inventors of the present invention considered it important to further consider not only the total pressure ratio P1 / P2 but also the gas permeability of the flow path FP.

[0069] Figure 4 is a schematic diagram showing the method for measuring the gas permeability of the flow path FP in this embodiment. In the figure, some of the piping is simplified and shown with solid lines.

[0070] A gas permeability measuring device 10 is used to measure the gas permeability of the flow path FP. The gas permeability measuring device 10 includes a gas supply unit 11, an upstream pressure gauge 12, a downstream pressure gauge 13, a flow meter 14, a vacuum pump 15, and a concentration meter 16. First, in the separation device 100, the perforated plate 120, the housing unit 130, and the piping 150, which constitute the flow path FP, are placed between the gas supply unit 11 and the vacuum pump 15. Then, the gas supply unit 11 and the inlet of the flow path FP are connected by piping, etc. Also, the outlet of the flow path FP and the vacuum pump 15 are connected by piping, etc.

[0071] The gas supply unit 11 is composed of, for example, a gas tank and a mass flow controller. The gas supplied by the gas supply unit 11 is the main component of the permeate gas G2. In this embodiment, the supply gas G1 is the atmosphere, and the concentration and partial pressure of nitrogen gas in the supply gas G1 are much higher than the concentration and partial pressure of carbon dioxide gas. Therefore, although the carbon dioxide gas permeability A of the separation membrane 110 is higher than the nitrogen gas permeability B, the amount of nitrogen gas permeation is greater than the amount of carbon dioxide gas permeation. In other words, in this embodiment, the main component of the permeate gas G2 is nitrogen gas. Therefore, the gas supply unit 11 supplies single-gas nitrogen gas. However, if the supply gas is not the atmosphere, and the concentration and partial pressure of carbon dioxide gas in the supply gas are higher than the concentration and partial pressure of nitrogen gas, the main component of the permeate gas will be carbon dioxide gas. In this case, the gas supply unit should supply carbon dioxide gas.

[0072] To measure the gas permeability of the flow path FP, first, the flow path FP is depressurized to 3 kPa by the vacuum pump 15. Next, gas is supplied to the inlet of the flow path FP at 103 kPa by the gas supply unit 11. In this embodiment, the inlet of the flow path FP is a perforated plate 120. This causes the gas to start flowing through the flow path FP. Then, the vacuum pump 15 sucks up the gas that has permeated through the flow path FP. At this time, the absolute pressure of the gas supplied to the inlet of the flow path FP is measured by the upstream pressure gauge 12. The absolute pressure of the gas permeating the outlet of the flow path FP is measured by the downstream pressure gauge 13. The volume of gas permeating the outlet of the flow path FP per unit time is measured by the flow meter 14. The amount of substance per unit volume of gas recovered by the vacuum pump 15 is measured by the concentration meter 16. Other test conditions, such as the test temperature, shall, as far as possible, conform to JIS K 7126-1:2006.

[0073] Immediately after gas supply, the flow rate of gas permeating through the flow path FP and the absolute pressure downstream of the flow path FP gradually increase, and then the flow rate and absolute pressure stabilize to a nearly constant state. In the stable state, the absolute pressure upstream is denoted as P3, and the absolute pressure downstream as P4. Furthermore, the amount of gas permeating through the outlet of the flow path FP per unit time is calculated from the volume of gas per unit time and the amount of gas per unit volume in the stable state. This amount of gas per unit time is denoted as n. Also, the area to which gas is supplied at the inlet of the flow path FP is denoted as s1. In this embodiment, the area s1 to which gas is supplied at the inlet of the flow path FP corresponds to the area of ​​the upper surface of the perforated plate 120.

[0074] Let C be the gas permeability of the flow path FP. By substituting the above values ​​into (Equation 7) below, the gas permeability C of the flow path FP can be calculated. C=n / {(P3-P4)·s1} (Equation 7)

[0075] The unit of the gas permeability C above is mol·m -2 ·s -1 ·Pa -1 The gas permeability C is used, along with the carbon dioxide gas permeability A and nitrogen gas permeability B, in the calculation of the parameters described later. Therefore, the units of gas permeability C must be the same as the units of carbon dioxide gas permeability A and nitrogen gas permeability B. When using GPU as the unit for carbon dioxide gas permeability A and nitrogen gas permeability B, the value calculated in (Equation 7) is 3.35 × 10⁻¹⁰. -10 Divide by . Since gas permeability C is measured using the main component gas of permeate gas G2, it can be considered as the permeability of permeate gas G2 in the flow path FP. The gas permeability measuring device 10 may also be used to measure carbon dioxide gas permeability A and nitrogen gas permeability B. In this case, with the separation membrane 110 installed in the chamber as in JIS K 7126-1:2006, connect the upstream side of the chamber to the gas supply unit 11 with piping, and connect the downstream side of the chamber to the vacuum pump 15 with piping. When measuring carbon dioxide gas permeability A, the gas supply unit 11 supplies a single gas of carbon dioxide, and when measuring nitrogen gas permeability B, the gas supply unit 11 supplies a single gas of nitrogen.

[0076] Theoretically, when two gas permeators are arranged in a continuous manner, if the gas permeability of the upstream gas permeator is x and the gas permeability of the downstream gas permeator is y, then the total gas permeability z of the two gas permeators combined can be expressed by the following equation (8).

[0077] 1 / z = 1 / x + 1 / y (Equation 8) By transforming (Equation 8), we obtain the following (Equation 9). z = (xy) / (x + y) (Equation 9)

[0078] The separation membrane 110 can be considered as an upstream gas permeator, and the flow channel FP can be considered as a downstream gas permeator. Therefore, when the carbon dioxide gas permeability of the separation device 100 is z1, the carbon dioxide gas permeability z1 of the separation device 100 is considered to be expressed by the following (Equation 10) as a combination of the carbon dioxide gas permeability A of the separation membrane 110 and the gas permeability C of the flow channel FP.

[0079] z1=(AC) / (A+C) (Equation 10) Similarly, when the nitrogen gas permeability of the separation device 100 is z2, the nitrogen gas permeability z2 of the separation device 100 is considered to be expressed by the following equation (Equation 11). z2=(BC) / (B+C) (Equation 11)

[0080] Let α be the selectivity ratio of the separation device 100. Based on (Equation 10) and (Equation 11), the selectivity ratio α of the separation device 100 is considered to be expressed by (Equation 12) below. α=z1 / z2={(B+C) / (A+C)}·(A / B) (Equation 12)

[0081] Based on (Equation 12), the selectivity ratio α of the separation device 100 can be determined by multiplying the selectivity ratio A / B of the separation membrane 110 by (B+C) / (A+C). Therefore, (B+C) / (A+C) can be considered as a multiplier of the selectivity ratio.

[0082] Hereafter, (B+C) / (A+C) will also be referred to as the "selectivity ratio (B+C) / (A+C)". In the selectivity ratio (B+C) / (A+C), the carbon dioxide gas permeability A and nitrogen gas permeability B are determined by the performance of the separation membrane 110 incorporated into the separation device 100. The nitrogen gas permeability B is smaller than the carbon dioxide gas permeability A. Therefore, regardless of the value of the gas permeability C of the flow path FP, the selectivity ratio (B+C) / (A+C) should be less than 1. Furthermore, as the value of the gas permeability C of the flow path FP increases, the influence of the magnitudes of the carbon dioxide gas permeability A and nitrogen gas permeability B can be reduced, and the selectivity ratio (B+C) / (A+C) approaches 1.

[0083] Therefore, it is clear that increasing the gas permeability C of the flow channel FP is important in order to increase the selectivity ratio α of the separation device 100. Furthermore, considering only the effect of gas permeability C, it is thought that the selectivity ratio α of the separation device 100 can be made to less than 100% of the selectivity ratio A / B of the separation membrane 110 but 80% or more if the flow channel FP of the separation device 100 is designed to satisfy the following equation (Equation 13). 1>(B+C) / (A+C)≧0.8 (Equation 13)

[0084] However, in reality, even if equation (Equation 13) is satisfied, the selectivity ratio α of the separation device 100 may not be 80% or more of the selectivity ratio A / B of the separation membrane 110 due to other factors such as insufficient pressure reduction from the aforementioned pump 160. Thus, (B+C) / (A+C) does not necessarily correspond to the selectivity ratio multiplier, but for the sake of clarity, (B+C) / (A+C) will be referred to as the selectivity ratio multiplier in the following explanation as well.

[0085] The gas permeability C of the flow path FP can be increased by reducing the pressure loss of the flow path FP. The pressure loss of the flow path FP can be adjusted by, for example, the area of ​​the separation membrane 110 in a top view, the length of the flow path FP, the surface roughness of the flow path FP, and the number of bends in the flow path FP. The shorter the length of the flow path FP, the smaller the pressure loss. The length of the flow path FP can be adjusted by, for example, the thickness of the porous plate 120, the length of the containment space 130s from the inlet 130a to the outlet 130b, and the length of the piping 150. The smaller the surface roughness of the flow path FP, the smaller the pressure loss. In this embodiment, the surface roughness of the flow path FP can be adjusted by the surface roughness of the forming surface of the through-hole 121 of the porous plate 120, and the surface roughness of the inner surfaces of the containment section 130 and the piping 150. The fewer the number of bends in the flow path FP, the smaller the pressure loss. The number of bends in the flow path FP can be adjusted by the shape of the containment space 130s of the containment section 130 and the internal space 151 of the piping 150.

[0086] Furthermore, in the flow path FP, if there is a portion where the permeate gas G2 constricts, the smaller the constriction rate, the smaller the pressure loss. In this embodiment, the permeate gas G2 constricts when it flows from the containment space 130s into the internal space of the pipe 150. Therefore, the closer the diameter of the internal space 151 of the pipe 150 is to the diameter of the containment space 130s, the smaller the pressure loss becomes. Also, the pressure loss when the permeate gas G2 constricts gradually is smaller than the pressure loss when the permeate gas G2 constricts all at once. Therefore, as described above, the pressure loss can be reduced by gradually decreasing the diameter D1 of the inlet portion FP11 of the flow path FP from upstream to downstream.

[0087] Furthermore, if there is a portion in the flow path where the permeate gas G2 expands, the smaller the expansion rate, the smaller the pressure loss. In this embodiment, the permeate gas G2 expands when it flows into the containment space 130s from each through hole 121 of the perforated plate 120. Therefore, the larger the diameter of each through hole 121 of the perforated plate 120, the smaller the pressure loss.

[0088] Furthermore, pressure loss can be reduced by making the shape of the containment space 130s such that there are fewer corners where the permeate gas G2 tends to accumulate. In this embodiment, the shape of the containment space 130s is cylindrical. Therefore, pressure loss can be reduced compared to cases where the containment space 130s is rectangular or polygonal prism-shaped.

[0089] Thus, the inventors of this application have clarified that in order to ensure that the selectivity ratio α of the separation device 100 is good relative to the selectivity ratio A / B of the separation membrane 110, it is important to consider both the total pressure ratio P1 / P2 and the gas permeability C of the flow path FP.

[0090] Next, we will explain the design method for the separation device 100 based on the above. Figure 5 is a flowchart showing the design method for the separation device 100 according to this embodiment. The design method for the separation device 100 comprises a step S1 of selecting the separation membrane 110, and a step S2 of designing the housing section 130, piping 150, and pump 160. Each step will be described in detail below.

[0091] In the selection process S1, a separation membrane with a capacity of 500,000 GPU ≥ A ≥ 1,000 GPU is selected as the separation membrane 110 to be incorporated into the separation device 100.

[0092] In design step S2, a pump capable of reducing the pressure in the containment space 130s of the containment section 130 is selected as the pump 160 to be incorporated into the separation device 100, such that (P1 / P2) / (A / B) ≥ 1. Also in design step S2, the flow path FP between the separation membrane 110 and the pump 160 is designed such that 1 > (B+C) / (A+C) ≥ 0.8.

[0093] Thus, the total pressure ratio P1 / P2 and the gas permeability C of the flow path FP required for the separation device 100 are clearly defined based on the carbon dioxide gas permeability A and nitrogen gas permeability B of the separation membrane 110 selected in the selection process S1. Therefore, the design of the separation device 100 becomes easier. As a result, a separation device 100 having a good selectivity ratio α relative to the selectivity ratio A / B of the separation membrane 110 can be easily obtained.

[0094] Next, the effects of this embodiment will be described. The separation device 100 is a separation device that selectively separates carbon dioxide gas from a supply gas G1 containing carbon dioxide gas and nitrogen gas. The separation device 100 comprises a separation membrane 110, a housing section 130, piping 150, and a pump 160. The separation membrane 110 includes a porous body 111 and a resin layer 112 disposed on the porous body 111, which selectively permeates carbon dioxide gas contained in the supply gas G1 toward the porous body 111. The housing section 130 holds the separation membrane 110 and has a housing space 130s formed for housing the permeate gas G2 that has permeated through the separation membrane 110. The piping 150 is connected to the housing section 130. The pump 160 depressurizes the housing space 130s via the piping 150 and sucks in the permeate gas G2. When the carbon dioxide gas permeability of the separation membrane 110 is A, 500,000 GPU ≥ A ≥ 1,000 GPU. Let B be the nitrogen gas permeability of the separation membrane 110, P1 be the total pressure of the supply gas G1, and P2 be the total pressure of the permeate gas G2 in the containment space 130s. Then (P1 / P2) / (A / B) ≥ 1. The flow path FP between the separation membrane 110 and the pump 160 of the permeate gas G2 includes the containment space 130s and the internal space 151 of the piping 150. When C is the gas permeability of the flow path FP, 1 > (B+C) / (A+C) ≥ 0.8.

[0095] In the above-described separation device 100, since (P1 / P2) / (A / B) ≥ 1, the concentration ratio c2 / c1 can be increased. A high concentration ratio c2 / c1 means that the carbon dioxide gas permeability z1 of the separation device 100 is high. This allows the selectivity ratio α of the separation device 100 to be increased. Furthermore, by setting 1 > (B+C) / (A+C) ≥ 0.8, the selectivity ratio (B+C) / (A+C) can be increased. This makes it possible to realize a separation device 100 with a good selectivity ratio α relative to the selectivity ratio A / B of the separation membrane 110.

[0096] Furthermore, 15 ≥ (P1 / P2) / (A / B). This suppresses an increase in the energy required to drive the pump 160. It also suppresses a shortening of the lifespan of the separation membrane 110.

[0097] Furthermore, in the flow path FP, the diameter D1 of the inlet FP11 where the permeate gas G2 flows from the containment section 130 into the pipe 150 gradually decreases from the upstream side to the downstream side. This reduces the pressure loss when the permeate gas G2 contracts. As a result, the gas permeability C of the flow path FP can be increased.

[0098] Furthermore, the flow path FP, which connects the containment space 130s of the containment section 130 and the internal space 151 of the piping 150, is configured in a straight line. Therefore, the pressure loss when the permeate gas G2 flows through the flow path FP can be reduced. As a result, the gas permeability C of the flow path FP can be increased.

[0099] Furthermore, pipe 150 extends in a straight line. Therefore, the pressure loss when the permeate gas G2 flows through pipe 150 can be reduced. As a result, the gas permeability C of the flow path FP can be increased.

[0100] Furthermore, the porous body 111 may include a polymer material, a ceramic material, or a metallic material. If the porous body 111 includes a polymer material, the gas permeability of the porous body 111 can be increased. If the porous body 111 includes a ceramic material or a metallic material, the mechanical strength of the porous body 111 can be increased.

[0101] Furthermore, the resin layer 112 contains organopolysiloxane. This increases the carbon dioxide gas permeability of the resin layer 112. As a result, the selectivity ratio A / B of the separation membrane 110 can be increased.

[0102] Furthermore, the design method for the separation device 100 is a design method for a separation device 100 that selectively separates carbon dioxide gas from a supply gas G1 containing carbon dioxide gas and nitrogen gas. The design method for the separation device 100 comprises a step S1 of selecting a separation membrane 110, and a step S2 of designing a housing section 130, piping 150, and a pump 160. The separation membrane 110 includes a porous body 111 and a resin layer 112 disposed on the porous body 111, which is permeable to carbon dioxide gas contained in the supply gas G1 toward the porous body 111. The housing section 130 holds the separation membrane 110 and has a housing space 130s formed for housing the permeate gas G2 that has permeated through the separation membrane 110. The piping 150 is connected to the housing section 130. The pump 160 depressurizes the housing space 130s via the piping 150 and sucks in the permeate gas G2. The flow path FP between the separation membrane 110 and the pump 160 for the permeate gas G2 includes the containment space 130s and the internal space 151 of the piping 150. In the selection step S1, when the carbon dioxide gas permeability of the separation membrane 110 is A, a separation membrane 110 is selected such that 500,000 GPU ≥ A ≥ 1,000 GPU. In the design step S2, when the nitrogen gas permeability of the separation membrane 110 is B, the total pressure of the supply gas G1 is P1, and the total pressure of the permeate gas G2 in the containment space 130s is P2, a pump 160 capable of reducing the pressure in the containment space 130s is selected such that (P1 / P2) / (A / B) ≥ 1. Also in the design step S2, when the gas permeability of the flow path is C, the flow path FP is designed such that 1 > (B+C) / (A+C) ≥ 0.8.

[0103] According to the design method for the separation device 100 described above, the designer can easily determine the total pressure ratio P1 / P2 required for the separation device 100 and the gas permeability C required for the flow path FP, based on the carbon dioxide gas permeability A and nitrogen gas permeability B of the selected separation membrane 110. Therefore, the designer can easily design a separation device 100 that has a good selectivity ratio α relative to the selectivity ratio A / B of the separation membrane 110. Furthermore, since the performance required for the pump 160 and the gas permeability C required for the flow path FP are clear, the designer can avoid selecting a pump 160 with excessive performance or excessively reducing the pressure loss of the flow path FP when designing the separation device 100. This reduces the manufacturing cost of the separation device 100.

[0104] Furthermore, in the design process S2, the shape of the containment space 130s, the inner diameter of the piping 150, the length of the flow path FP, the surface roughness of the flow path FP, or the number of bends in the flow path FP are adjusted so that 1 > (B + C) / (A + C) ≥ 0.8. This makes it possible to realize a separation device 100 that has a good selectivity ratio α with respect to the selectivity ratio A / B of the separation membrane 110.

[0105] <Second Embodiment> Next, a separation device 200 according to the second embodiment will be described. Figure 6 is a cross-sectional view showing the separation device 200 according to this embodiment. The separation device 200 differs from the separation device 100 according to the first embodiment in that it further comprises another separation membrane 210, another perforated plate 220, another housing section 230, another fixing member 240, and another piping 250. The following description will mainly focus on the differences between the second embodiment and the first embodiment, and descriptions of configurations similar to those of the first embodiment will be omitted as appropriate. The same applies to the description of the modified examples described later.

[0106] The separation membrane 110 is also called the "first separation membrane 110". The perforated plate 120 is also called the "first perforated plate 120". The housing section 130 is also called the "first housing section 130". The piping 150 is also called the "first piping 150". The other separation membrane 210 is also called the "second separation membrane 210". The other perforated plate 220 is also called the "second perforated plate 220". The other housing section 230 is also called the "second housing section 230". The fixing member 140 is also called the "first fixing member 140". The other fixing member 240 is also called the "second fixing member 240". The other piping 250 is also called the "second piping 250".

[0107] The second separation membrane 210 selectively permeates carbon dioxide gas contained in the supply gas G1. Hereinafter, the gas that has permeated through the second separation membrane 210 will be referred to as "other permeated gas G3". The second separation membrane 210 includes another porous body 211 and another resin layer 212 disposed on the other porous body 211, which selectively permeates carbon dioxide gas contained in the supply gas G1 toward the other porous body 211. The other porous body 211 is constructed in the same way as the porous body 111 of the first separation membrane 110. The other resin layer 212 is constructed in the same way as the resin layer 112 of the first separation membrane 110. Therefore, the selectivity ratio of the second separation membrane 210 is approximately the same as the selectivity ratio A / B of the first separation membrane 110.

[0108] The second perforated plate 220 is positioned beneath the second separation membrane 210 and supports the second separation membrane 210. The second perforated plate 220 is constructed similarly to the first perforated plate 120.

[0109] The second containment section 230 has other containment spaces 230s formed therein for containing other permeable gases G3. The second containment section 230 is configured in the same way as the first containment section 130. In this embodiment, the second containment section 230 is separated from the first containment section 130, and the other containment spaces 230s are separated from the containment spaces 130s. However, the first containment section and the second containment section may be in contact with each other, or the first containment section and the second containment section may be a single unit as long as the containment spaces are separated from the other containment spaces.

[0110] The second fixing member 240 fixes the second separation membrane 210 and the second perforated plate 220 to the second housing section 230. The second fixing member 240 is configured in the same way as the first fixing member 140. In this embodiment, the lower end of the first pipe 150 is not directly connected to the pump 160. The upper end of the second pipe 250 is connected to the second housing section 230. The second pipe 250 is configured in the same way as the first pipe 150.

[0111] The separation device 200 further comprises a third pipe 270 connected to the lower ends of the first pipe 150 and the second pipe 250, and a fourth pipe 280 connecting the third pipe 270 to the pump 160. The third pipe 270 extends linearly from the lower end of the first pipe 150 toward the lower end of the second pipe 250. The internal space of the third pipe 270 communicates with the internal space 151 of the first pipe 150 and the internal space of the second pipe 250. The fourth pipe 280 extends in the Z-axis direction. The upper end of the fourth pipe 280 is connected to the approximate center of the longitudinal direction of the third pipe 270. The internal space of the fourth pipe 280 communicates with the internal space of the third pipe 270. The lower end of the fourth pipe 280 is connected to the pump 160.

[0112] The fourth pipe 280 is connected to the third pipe 270 such that its upper end is approximately flush with the inner surface of the third pipe 270. The diameter D2 of the upper end of the internal space of the fourth pipe 280 gradually decreases from upstream to downstream. This reduces pressure loss when permeate gas G2 and other permeate gases G3 flow from the third pipe 270 into the fourth pipe 280.

[0113] Pump 160 reduces the pressure in the containment space 130s via the first pipe 150, the third pipe 270, and the fourth pipe 280. Pump 160 also reduces the pressure in the other containment space 230s via the second pipe 250, the third pipe 270, and the fourth pipe 280.

[0114] Next, the flow of permeate gas G2 and other permeate gases G3 in the separation device 200 will be described. The permeate gas G2 that has passed through the first separation membrane 110 is drawn into the pump 160 and recovered via the first perforated plate 120, the first containment section 130, the first piping 150, the third piping 270, and the fourth piping 280. The other permeate gas G3 that has passed through the second separation membrane 210 is drawn into the pump 160 and recovered via the second perforated plate 220, the second containment section 230, the second piping 250, the third piping 270, and the fourth piping 280.

[0115] The flow path between the first separation membrane 110 and the pump 160 for the permeate gas G2 is referred to as "flow path FP1". Flow path FP1 includes multiple through holes 121 in the first perforated plate 120, the accommodation space 130s of the first accommodation section 130, the internal space 151 of the first piping 150, a portion of the internal space of the third piping 270, and the internal space of the fourth piping 280. The flow path between the second separation membrane 210 and the pump 160 for the other permeate gas G3 is referred to as "other flow path FP2". Other flow path FP2 includes multiple through holes in the second perforated plate 220, other accommodation spaces 230s of the second accommodation section 230, the internal space of the second piping 250, a portion of the internal space of the third piping 270, and the internal space of the fourth piping 280. The shapes of flow path FP1 and other flow path FP2 are generally symmetrical with respect to a plane P located between the first accommodation section 130 and the second accommodation section 230 and parallel to the ZX plane.

[0116] Figure 7 is a schematic diagram showing the method for measuring the gas permeability C of the flow path FP1 in this embodiment. In the figure, some of the piping is simplified and shown with solid lines.

[0117] First, in the separation device 200, both the part constituting the flow path FP1 and the part constituting the other flow path FP2 are placed between the gas supply unit 11 and the vacuum pump 15 of the gas permeability measuring device 10. That is, the first perforated plate 120, the first housing unit 130, the first piping 150, the second perforated plate 220, the second housing unit 230, the second piping 250, the third piping 270, and the fourth piping 280 are placed between the gas supply unit 11 and the vacuum pump 15. Then, the gas supply unit 11 and the inlet of flow path FP1 and the gas supply unit 11 and the inlet of the other flow path FP2 are connected by piping. In addition, the outlets of flow path FP1 and the other flow path FP2 are connected to the vacuum pump 15 by piping.

[0118] Next, the vacuum pump 15 reduces the pressure in flow path FP1 and the other flow path FP2. Then, the gas supply unit 11 supplies gas to the inlets of flow path FP1 and the other flow path FP2. The vacuum pump 15 sucks up the gas that has permeated through flow path FP1 and the other flow path FP2. At this time, the absolute pressure of the gas supplied to the inlet of flow path FP1 or the other flow path FP2 is measured by the upstream pressure gauge 12. The absolute pressure of the gas permeating through the outlets of flow path FP1 and the other flow path FP2 is measured by the downstream pressure gauge 13. The volume of gas permeating through the outlets of flow path FP1 and the other flow path FP2 per unit time is measured by the flow meter 14. The amount of substance per unit volume of gas recovered by the vacuum pump 15 is measured by the concentration meter 16.

[0119] Let s1 be the sum of the area supplied with gas at the inlet of channel FP1 and the area supplied with gas at the inlet of the other channel FP2. In this embodiment, area s1 corresponds to the sum of the upper surface area of ​​the first porous plate 120 and the upper surface area of ​​the second porous plate 220. Similar to the first embodiment, the gas permeability C can be calculated by substituting the upstream absolute pressure P3, the downstream absolute pressure P4, the amount of substance n per unit time, and the area s1 into (Equation 7).

[0120] Gas permeability C represents the amount of gas permeating per unit time, unit pressure, and unit area. As mentioned above, the shape of channel FP1 and the shape of the other channel FP2 are generally symmetrical. Therefore, the calculated gas permeability C may be the gas permeability of channel FP1 or the gas permeability of the other channel FP2. If there are multiple channels and it is expected that the gas permeability of each channel will differ from one another, the above measurement method should be performed with the channels other than the one to be measured blocked.

[0121] In this embodiment, the first separation membrane 110 and the second separation membrane 210 are configured similarly. Therefore, if 500,000 GPU ≥ A ≥ 1,000 GPU, (P1 / P2) / (A / B) ≥ 1, and 1 > (B+C) / (A+C) ≥ 0.8, a separation device 200 can be obtained that has a good selectivity ratio α for the selectivity ratio A / B of both the first separation membrane 110 and the second separation membrane 210.

[0122] Furthermore, if the separation device is equipped with multiple separation membranes and the selectivity ratios of the multiple separation membranes differ from each other, it is preferable that the three inequalities described above be satisfied for all separation membranes. However, if the three inequalities above are satisfied for the selectivity ratio of at least one separation membrane, a separation device with a good selectivity ratio for at least one separation membrane can be obtained. The number of separation membranes provided in the separation device may be three or more.

[0123] Furthermore, the separation device 200 according to this embodiment further comprises another separation membrane 210, another containment section 230, and another piping 250. The other separation membrane 210 includes another porous body 211 and another resin layer 212 disposed on the other porous body 211 and selectively permeating carbon dioxide gas contained in the supply gas G1 toward the other porous body 211. The other containment section 230 holds the other separation membrane 210 and has a separate containment space 230s for containing the other permeate gas G3 that has permeated through the other separation membrane 210. The other piping 250 is connected to the other containment section 230. The pump 160 depressurizes the other containment space 230s via the other piping 250. This allows the flow path from the separation membrane 110 to the piping 150 to be separated from the flow path from the other separation membrane 210 to the other piping 250. Therefore, the separation device 200 can reduce pressure loss compared to the case where the permeate gases from multiple separation membranes flow into one containment section and one piping.

[0124] <Example 1> Next, we will describe the separation membrane 310 according to the modified example 1. Figure 8 is a cross-sectional view showing the separation membrane 310 according to this modified example.

[0125] The separation membrane 310 differs from the separation membrane 110 in the first embodiment in that the porous body 311 includes a plurality of stacked porous layers 313, 314.

[0126] Multiple pores 313h are formed in the porous layer 313. Each pore 313h penetrates the porous layer 313 in the thickness direction. The multiple pores 313h are formed dispersed on the XY plane. The porous layer 314 is placed on the porous layer 313. The resin layer 112 is placed on the porous layer 314. Multiple pores 314h are formed in the porous layer 314. Each pore 314h penetrates the porous layer 314 in the thickness direction. The multiple pores 314h are formed to be dispersed on the XY plane. The diameter of the pores 313h is larger than the diameter of the pores 314h.

[0127] In other words, each of the multiple porous layers 313 and 314 has pores 313h and 314h that penetrate through each of the multiple porous layers 313 and 314 in the thickness direction. The pores 313h of the porous layer 313 that are further away from the resin layer 112 have a larger diameter. As a result, the flow of carbon dioxide gas that has permeated through the resin layer 112 gradually expands as it permeates through the porous body 311 and reaches the containment space 130s. Therefore, pressure loss can be reduced. Also, since the pores 314h of the porous layer 314 that are closer to the resin layer 112 have a smaller diameter, the porous body 311 can support the resin layer 112 well. This increases the mechanical strength of the separation membrane 310.

[0128] <Modification 2> Next, a description of the separation membrane 410 according to modified example 2 will be provided. Figure 9 is a cross-sectional view showing the separation membrane 410 according to this modified example.

[0129] The separation membrane 410 differs from the separation membrane 110 in the first embodiment in the shape of the pores 413h formed in the porous body 411.

[0130] The porous body 411 includes a porous layer 413 that supports the resin layer 112. The porous layer 413 has pores 413h that penetrate through the porous layer 413 in the thickness direction. The diameter of the pores 413h increases continuously in the direction from the resin layer 112 toward the porous layer 413. That is, the shape of the pores 413h is frustoconical. As a result, the flow of carbon dioxide gas that has permeated through the resin layer 112 gradually expands as it permeates through the porous body 411 and reaches the containment space 130s. Therefore, pressure loss can be reduced. In addition, since the diameter of the pores 413h is smaller in the part of the porous layer 413 closer to the resin layer 112, the porous layer 413 can support the resin layer 112 well. This increases the mechanical strength of the separation membrane 410.

[0131] <Variation 3> Next, we will describe the separation membrane 510 according to the modified example 3. Figure 10 is a cross-sectional view showing the separation membrane 510 according to this modified example.

[0132] The separation membrane 510 differs from the separation membrane 410 in modified example 2 in the shape of the pores 513h formed in the porous body 511.

[0133] The porous body 511 includes a porous layer 513 that supports the resin layer 112. The porous layer 513 has pores 513h that penetrate through the porous layer 513 in the thickness direction. The diameter of the pores 513h increases in a stepwise manner from the resin layer 112 toward the porous layer 513. This configuration can also obtain the same effects as in the modified example 2.

[0134] Furthermore, the shapes of the pores 413h and 513h in Modified Example 2 or Modified Example 3 may be applied to the pores 313h and 314h in Modified Example 1. That is, the diameter of the pore 313h may increase continuously or stepwise as it moves away from the resin layer 112. The same applies to the pore 314h. In this case, it is preferable that the diameter of the pore 313h on the upper surface of the porous layer 313 is larger than the diameter of the pore 314h on the lower surface of the porous layer 314. [Examples]

[0135] Next, we will describe some examples. Figure 11 is a cross-sectional view showing the separation apparatus 900 according to Comparative Example 1. Figure 12 is Table 1, which shows the configuration and evaluation results of the separation apparatuses for Examples 1-3 and Comparative Examples 1-3.

[0136] We used spreadsheet software to simulate how the selectivity ratio α of the separation device changes depending on the pressure reduction amount of the separation device's pump and the gas permeability C of the flow path.

[0137] Separation apparatuses were set up according to Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3. The ambient temperature of each separation apparatus was set to 20°C. The supply gas supplied to each separation apparatus contained carbon dioxide and nitrogen gas. To simulate atmospheric conditions, the total pressure P1 of the supply gas was set to 103 kPa and the concentration of carbon dioxide gas was set to 400 ppm.

[0138] The separation apparatus according to Example 1 was configured to have the same structure as the separation apparatus 200 according to the second embodiment. That is, the separation apparatus according to Example 1 was assumed to include a first separation membrane, a first perforated plate, a first housing section, a first pipe, a second separation membrane, a second perforated plate, a second housing section, a second pipe, a third pipe, a fourth pipe, and a pump. Then, as shown in Table 1, the carbon dioxide gas permeability A and nitrogen gas permeability B of the separation membrane were set. The selectivity ratio A / B of the separation membrane was calculated from the carbon dioxide gas permeability A and nitrogen gas permeability B.

[0139] Furthermore, the total pressure immediately before the pump in Example 1 was set to 0.040 kPa. The total pressure immediately before the pump corresponds to the pump's pressure reduction. In addition, although not shown in the table, flow path settings such as the area of ​​each separation membrane, the opening area and thickness of each perforated plate, the inner diameter and total length of each containment section, the inner diameter and total length of each pipe, and the loss coefficient based on the shape of each inlet section were set. Note that the area of ​​each separation membrane corresponds to the area of ​​the flow path inlet. Based on the flow path settings and the density of nitrogen gas, the pressure loss when nitrogen gas flows through the flow path was simulated using the pressure loss theory formula of Darcy-Weisbach et al. Then, the gas permeability C of the flow path was calculated based on the pressure loss. Furthermore, the total pressure P2 of the permeate gas in the containment section was simulated from the pressure loss and the total pressure immediately before the pump.

[0140] Furthermore, the selectivity ratio (B+C) / (A+C) was calculated from the carbon dioxide gas permeability A, nitrogen gas permeability B, and gas permeability C. The total pressure ratio P1 / P2 and (P1 / P2) / (A / B) were calculated from the total pressure P1 of the supply gas and the total pressure P2 of the permeate gas.

[0141] When (P1 / P2) / (A / B) ≥ 1, the gas permeability C was considered to have the dominant influence on the selectivity ratio α of the separation device, and the selectivity ratio α of the separation device was calculated based on (Equation 12). On the other hand, when 1 > (P1 / P2) / (A / B), the total pressure ratio P1 / P2 was considered to have the dominant influence on the selectivity ratio α of the separation device, and the total pressure ratio P1 / P2 was taken as the selectivity ratio α of the separation device. These results are shown in Table 1.

[0142] The structure of the separation apparatus in Example 2 is the same as that of the separation apparatus in Example 1, except that the lengths of the first and second pipes are increased. Therefore, the gas permeability C in Example 2 is lower than that of Example 1. In addition, in Example 2, the set value of the total pressure immediately before the pump was set to a smaller value than in Example 1.

[0143] The structure of the separation apparatus in Example 3 is the same as that of the separation apparatus in Example 2. In Example 3, the carbon dioxide gas permeability A was set to a larger value than in Example 2, the nitrogen gas permeability B was set to a larger value than in Example 2, and the total pressure immediately before the pump was set to a larger value than in Example 2.

[0144] As shown in Figure 11, in the separation apparatus 900 according to Comparative Example 1, the first separation membrane 110 and the second separation membrane 210 are fixed to a single housing section 930, and it is assumed that the piping 950 connecting the housing section 930 and the pump 160 is not straight but has two bends 952 and 953. Furthermore, the inner diameter of the piping 950 was set to a smaller value than the inner diameter of each pipe in Example 1. Consequently, the gas permeability C of Comparative Example 1 was lower than the gas permeability C of Examples 1 to 3. In addition, the carbon dioxide gas permeability A, nitrogen gas permeability B, and the total pressure immediately before the pump were set to the same values ​​as in Example 3.

[0145] The structure of the separation apparatus in Comparative Example 2 is the same as that of the separation apparatus in Comparative Example 1, except that the length of the piping 950 is shortened. Therefore, the gas permeability C of Comparative Example 2 is higher than that of Comparative Example 1. In addition, in Comparative Example 2, the carbon dioxide gas permeability A was set to a smaller value than in Comparative Example 1, the nitrogen gas permeability B was set to a smaller value than in Comparative Example 1, and the total pressure immediately before the pump was set to a smaller value than in Comparative Example 1.

[0146] The structure of the separation apparatus in Comparative Example 3 is the same as that of the separation apparatus in Example 1, except that the lengths of the first and second pipes are shortened while the inner diameters of the first, second, and fourth pipes are increased. Therefore, the gas permeability C of Comparative Example 3 was higher than that of Examples 1 to 3. In addition, in Comparative Example 3, the nitrogen gas permeability B was set to a smaller value than in Example 1, and the total pressure immediately before the pump was set to a larger value than in Example 1.

[0147] For Examples 2, 3, and Comparative Examples 1-3, the selectivity ratio A / B of the separation membrane, the selectivity ratio multiplier (B+C) / (A+C), the total pressure P2 of the permeate gas, the total pressure ratio P1 / P2, (P1 / P2) / (A / B), and the selectivity ratio α of the separation device were calculated in the same manner as in Example 1. In addition, for Examples 1-3 and Comparative Examples 1-3, the decrease rate of the selectivity ratio α of the separation device relative to the selectivity ratio A / B of the separation membrane was calculated. The separation devices were then evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0148] S: Decrease rate of selection ratio is 20% or less T: Decrease in selection ratio exceeds 20%

[0149] In the separation apparatuses of Examples 1, 2, and 3, (P1 / P2) / (A / B) ≥ 1 and 1 > (B+C) / (A+C) ≥ 0.8. In all of these cases, the rate of decrease in selectivity was 20% or less. Therefore, it was found that the separation apparatuses of Examples 1, 2, and 3 have a good selectivity α relative to the selectivity A / B of the separation membrane. In particular, the rate of decrease in selectivity of Example 1 is smaller than that of Examples 2 and 3. This is thought to be because the pressure loss in the flow path of Example 1 is smaller than that in the flow paths of Examples 2 and 3.

[0150] In the separation apparatuses of Comparative Examples 1 and 2, (P1 / P2) / (A / B) ≥ 1, but 0.8 > (B+C) / (A+C). In these cases, the decrease in selectivity exceeded 20%. This is thought to be because, although the pump's depressurization amount was sufficient, the pressure loss in the flow path of Comparative Examples 1 and 2 was greater than the pressure loss in the flow path of Examples 1 to 3.

[0151] Furthermore, in the separation apparatus related to Comparative Example 3, although 1 > (B + C) / (A + C) ≥ 0.8, 1 > (P1 / P2) / (A / B). In this case, the decrease in selectivity also exceeded 20%. This is thought to be because, although the pressure loss in the flow path was reduced, the amount of pressure reduction by the pump was insufficient.

[0152] As explained above, it was found that to improve the selectivity ratio α of the separation device, it is important to satisfy both (P1 / P2) / (A / B)≧1 and 1>(B+C) / (A+C)≧0.8. The inventors of this application also conducted supplementary experiments and confirmed that they could obtain a trend similar to the simulation results. Furthermore, it was confirmed that a flow path with the gas permeability C shown in Table 1 can be realized by using the method for reducing the pressure loss in the flow path described above. Similarly, it was confirmed that the total pressure ratio P1 / P2 shown in Table 1 can be achieved by adjusting the amount of pressure reduction in the pump.

[0153] Although the separation apparatus according to the present invention has been described above based on the illustrated embodiments and modifications, the present invention is not limited thereto.

[0154] For example, in the separation apparatus according to the present invention, each part of the above-described embodiment and modified example may be replaced with any component having a similar function, or any component may be added to the above-described embodiment and modified example. The same applies to the design method of the separation apparatus according to the present invention. [Explanation of Symbols]

[0155] 10... Measuring device, 11... Gas supply unit, 12... Upstream pressure gauge, 13... Downstream pressure gauge, 14... Flow meter, 15... Vacuum pump, 16... Concentration meter, 100... Separation device, 110... Separation membrane, 110a... First surface, 110b... Second surface, 111... Porous material, 112... Resin layer, 113... Porous layer, 113h... Cavity, 120... Perforated plate, 121... Through hole, 130... Containment unit, 130a... Removal Inlet, 130b…Outlet, 130c…Step, 130s…Storage space, 131…First wall, 132…Second wall, 133…Side wall, 140…Fixing member, 141…Fixing device, 150…Piping, 151…Internal space, 160…Pump, 200…Separation device, 210…Other separation membrane, 211…Other porous material, 212…Other resin layer, 220…Other perforated plate, 230…Other storage section, 230s ...other containment space, 240...other fixing member, 250...other piping, 270...third piping, 280...fourth piping, 310...separation membrane, 311...porous material, 313...porous layer, 313h...vacuum, 314...porous layer, 314h...vacuum, 410...separation membrane, 411...porous material, 413...porous layer, 413h...vacuum, 510...separation membrane, 511...porous material, 513...porous layer, 513h ...hole, 900...separation device, 930...housing section, 950...piping, 952...bend, 953...bend, C1...central axis, D1...diameter, D2...diameter, FP...flow path, FP1...flow path, FP2...other flow path, FP11...inlet section, G1...supply gas, G2...permeate gas, G3...other permeate gas, P...plane, PS1...pressure gauge, PS2...pressure gauge, S1...selection process, S2...design process

Claims

1. A separation apparatus for selectively separating carbon dioxide gas from a supply gas containing carbon dioxide gas and nitrogen gas, A separation membrane comprising a porous body and a resin layer disposed on the porous body, which selectively permeates the carbon dioxide gas contained in the supply gas toward the porous body, A containment section is formed which holds the separation membrane and contains a containment space for containing the permeate gas that has permeated through the separation membrane, The piping connected to the aforementioned housing section, A pump that reduces the pressure in the containment space via the aforementioned piping and sucks out the permeate gas, Equipped with, When the carbon dioxide gas permeability of the separation membrane is A, 500,000GPU≧A≧1,000GPU And, When the nitrogen gas permeability of the separation membrane is B, the total pressure of the supply gas is P1, and the total pressure of the permeate gas in the containment space is P2, (P1 / P2) / (A / B)≧1 And, The flow path of the permeate gas between the separation membrane and the pump includes the containment space and the internal space of the piping. When the gas permeability of the aforementioned flow path is C, 1>(B+C) / (A+C)≧0.8 A separation device characterized by the following:

2. The separation apparatus according to claim 1, wherein 15 ≥ (P1 / P2) / (A / B).

3. A separation membrane comprising another porous body and another resin layer disposed on the other porous body, which selectively permeates the carbon dioxide gas contained in the supply gas toward the other porous body, Another containment section is formed which holds the other separation membrane and contains other containment spaces for containing other permeate gases that have permeated through the other separation membrane, Other piping connected to the other housing section, Furthermore, The separation apparatus according to claim 1 or 2, wherein the pump reduces the pressure of the other containment space via the other piping.

4. The separation apparatus according to claim 1 or 2, wherein in the flow path, the diameter of the inlet portion through which the permeate gas flows from the containment portion into the piping gradually decreases from the upstream side to the downstream side.

5. The separation apparatus according to claim 1 or 2, wherein the flow path connecting the containment space of the containment section and the internal space of the piping is configured in a straight line from the separation membrane.

6. The separation device according to claim 1 or 2, wherein the piping extends in a straight line.

7. The porous body includes a porous layer that supports the resin layer, The porous layer has voids formed that penetrate through the porous layer in the thickness direction. The separation apparatus according to claim 1 or 2, wherein the diameter of the pores increases continuously or stepwise in the direction from the resin layer toward the porous layer.

8. The porous body includes a plurality of stacked porous layers, Each of the plurality of porous layers has a void formed that penetrates each of the plurality of porous layers in the thickness direction. The separation apparatus according to claim 1 or 2, wherein the pores in the porous layer that are further away from the resin layer have a larger diameter.

9. The separation apparatus according to claim 1 or 2, wherein the porous body includes a polymer material, a ceramic material, or a metallic material.

10. The separation apparatus according to claim 1 or 2, wherein the resin layer comprises an organopolysiloxane.

11. A method for designing a separation apparatus that selectively separates carbon dioxide gas from a supply gas containing carbon dioxide gas and nitrogen gas, A step of selecting a separation membrane comprising a porous body and a resin layer disposed on the porous body, which is permeable to the carbon dioxide gas contained in the supply gas toward the porous body, A process of designing a housing section that holds the separation membrane and has a housing space formed for housing the permeate gas that has permeated through the separation membrane, piping connected to the housing section, and a pump that depressurizes the housing space via the piping and sucks out the permeate gas, Equipped with, The flow path of the permeate gas between the separation membrane and the pump includes the containment space and the internal space of the piping. In the aforementioned selection process, When the carbon dioxide gas permeability of the separation membrane is A, select the separation membrane such that 500,000 GPU ≥ A ≥ 1,000 GPU. In the aforementioned design process, When the nitrogen gas permeability of the separation membrane is B, the total pressure of the supply gas is P1, and the total pressure of the permeate gas in the containment space is P2, a pump capable of reducing the pressure in the containment space is selected such that (P1 / P2) / (A / B) ≥ 1. When the gas permeability of the aforementioned flow path is C, the flow path is designed such that 1 > (B + C) / (A + C) ≥ 0.

8. A method for designing a separation apparatus characterized by the following:

12. The design method for a separation apparatus according to claim 11, wherein in the design step, the shape of the containment space, the inner diameter of the piping, the length of the flow path, the surface roughness of the flow path, or the number of bends in the flow path are adjusted so that 1 > (B + C) / (A + C) ≥ 0.8.

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