JP2015066488A - Acid gas separation spiral module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acid gas separation module that suppresses condensed water generation and pressure loss.SOLUTION: In an acid gas separation spiral module, in which acid gas separation films, supply gas flow path members and penetration gas flow path members are wound around a perforated hollow core tube, the supply gas flow path member 30 is used, which is formed of a net prepared by making a plurality of yarn 31 and 32 intersect in a lattice shape, and in which: a plurality of sealing parts 35 are provided, each of which is formed by sealing at least one net mesh 34 in at least the surface direction; and the sealing parts 35 are arranged such that when converting an interval between the sealing parts 35 to frequency, occurrence of the sealing part is set to the value from the frequency raised to the power of -0.6 to the frequency raised to the power of -1.4, at which the occurrence increases as the frequency reduces.

Description

  The present invention relates to an acidic gas separation module that selectively separates acidic gas from a raw material gas containing water vapor using a facilitated transport membrane, and particularly relates to a spiral type module.

  2. Description of the Related Art Conventionally, development of separation membrane modules for concentrating raw fluids such as liquids and gases and separating specific components from raw fluids has been progressing. Among them, a spiral type module in which a separation membrane, a supply side flow path member, and a permeate side flow path member are wound around a perforated hollow central tube is known as one that performs efficient separation.

  In recent years, there has been a development of technology for collecting and concentrating carbon dioxide in exhaust gas, and technology for selectively separating acidic gas in mixed gas, which is used to obtain hydrogen-based gas for fuel cells. Progressing. As a separation membrane for acid gas, there is known a facilitated transport membrane in which an acid gas carrier is contained in the membrane, and separation is performed by transporting the acid gas to the opposite side of the membrane by this carrier (Patent Document 1). etc). The facilitated transport membrane exhibits good separation efficiency when separating acidic gas from a raw material containing water vapor at a high temperature of 100 ° C. or higher. The gas separation membrane module using the facilitated transport membrane comprises a separation membrane module unit in which a plurality of (three or more) gas separation membrane modules are connected in series to a pressure vessel, and the separation membrane module is further provided. A plurality of module units are connected to realize a gas separation device having high separation performance and processing capability.

  In the separation membrane module, in order to secure a flow path between the separation membrane and the gas to be treated and to generate a turbulent flow to improve the permeation rate of the permeated gas, a network-structured flow path member is adjacent to the separation membrane. And place it.

  In a separation membrane mainly for water, in order to promote this turbulent flow, a technique has been proposed in which a turbulent flow promoting mechanism such as irregularities, fins, and protrusions is provided on a supply-side channel member (Patent Document 2). 3).

JP 2013-027841 A JP-A-11-179352 JP 2009-50759 A

  However, it has been clarified by the present inventors that when a gas such as an acid gas is a separation target, there is a problem different from that when a liquid such as water is a separation target.

  As described above, the supply gas is a gas containing water vapor at a high temperature of 100 ° C. or higher, and it is necessary to supply the supply gas at a high pressure in order to process a plurality of modules connected in series. When supplying a supply gas containing high-pressure and high-temperature water vapor to the module, water is locally aggregated at the intersection of the yarns constituting the network structure constituting the supply-side flow path member, and the condensed water is separated into the acidic gas separation membrane. It has been found that contact with the substrate may cause undesired carrier elution and reduce the separation efficiency of the acid gas.

  The occurrence of turbulent gas flow in the flow path member is suppressed, the effect of suppressing concentration polarization of the gas to be treated due to turbulent flow is reduced, and there is a possibility that moisture is aggregated. According to these studies, when the turbulent flow promotion mechanism in the conventional aqueous separation membrane module is applied to the acidic gas separation module, there is a problem that the pressure loss increases. As described above, in order to use a plurality of modules connected in series, it is necessary to suppress the pressure loss of each unit, and an increase in pressure loss becomes a big problem when put into practical use.

  This invention is made | formed in view of the said situation, Comprising: In the spiral module for acidic gas separation, it aims at providing the module for acidic gas separation in which generation | occurrence | production of condensed water and pressure loss were suppressed. .

The spiral-type module for acid gas separation according to the present invention includes an acid gas separation membrane, a supply gas channel member, and a permeate gas channel member wound around a perforated hollow central tube. Spiral type module for
The supply gas flow path member is composed of a net formed by crossing a plurality of yarns in a lattice shape,
At least one of the eyes of the net has a plurality of sealing portions sealed at least in the surface direction,
When a plurality of sealing parts frequency-convert the interval between the sealing parts, the frequency increases with a decrease in frequency. It is characterized by being.

  The “net eye” is an opening (gap) in the lattice, and the sealing portion has a size that fills the surface direction of at least one net eye. The sealing portion may have a size (area) that continuously fills two or more eyes, but most preferably has a size (area) of about one eye.

  It is more preferable that the plurality of sealing portions be formed in an arrangement having a frequency of −0.8 or less and −1.2 or more, and it is more preferable as the frequency approaches −1.

It is preferable that the thickness d _c of the sealing portion is less than the net thickness d _n.

  In the spiral gas module for acid gas separation according to the present invention, the supply gas flow path member is composed of a net formed by crossing a plurality of yarns in a lattice pattern, and at least one of the net eyes is at least in the surface direction. When the plurality of sealing portions are frequency-converted between the sealing portions, the frequency multiplier is −0. By being arranged at intervals of 6 or less and −1.4 or more, generation of condensed water can be suppressed, and an increase in pressure loss can also be suppressed.

  The sealing part functions as a turbulent flow promoting part, the supply gas can be stirred, and generation of condensed water can be suppressed. When the generation of the condensed water is suppressed, it is possible to suppress the deterioration of the separation membrane (decrease in membrane performance) due to the elution of carriers from the separation membrane by water. Moreover, a pressure loss can be suppressed by arrange | positioning a sealing part by said space | interval. This is presumably because the main flow of the supply gas from the supply gas inlet toward the outlet can be maintained in the supply gas flow path member along the length direction of the central tube.

It is a schematic block diagram which provides the partial cutout which shows the spiral type module for acidic gas separation which concerns on embodiment of this invention. It is a plane schematic diagram of the member for supply gas passages of the present invention. FIG. 3 is an enlarged view showing a part of a supply gas channel member in FIG. 2. It is sectional drawing of the member for supply gas flow paths of FIG. It is an enlarged view which shows a part of member for supply gas flow paths of the other example. It is sectional drawing of the member for supply gas flow paths of FIG.

  The spiral-type module for acid gas separation of the present invention can separate various acid gases by selecting the type of carrier of the separation membrane for separating acid gases. Examples of the acid gas include carbon dioxide and hydrogen sulfide.

<Spiral type module for acid gas separation>
FIG. 1 is a schematic configuration diagram illustrating a spiral gas module 100 for acid gas separation according to an embodiment, which is partially cut away.
As shown in FIG. 1, the spiral module 100 has, as its basic structure, an acidic gas separation membrane 10, a supply gas flow path member 30, around a perforated hollow central tube (permeate gas collecting tube) 12, A laminated body 14 in which the acidic gas separation membrane 10 and the permeating gas channel member 6 are laminated in this order is wound in a single or plural number. And the outermost periphery is covered with the coating layer 16, and the telescope prevention board 18 is attached to both ends, respectively, and is comprised. When the raw material gas 20 containing the acidic gas is supplied from the one end portion 100A side of the module 100 having such a configuration, the raw material gas 20 is separated into the acidic gas 22 and the remaining gas 24 and the other end portion 100B side. Discharge separately.

  First, the supply gas channel member 30 will be described. The supply gas flow path member 30 is a member to which a source gas containing an acid gas is supplied from one end of the acid gas separation module, and has a function as a spacer.

  FIG. 2 is a schematic plan view of the supply gas flow path member 30. The supply gas flow path member 30 is composed of a net having a mesh structure in which a plurality of yarns 31 and 32 are crossed in a lattice pattern, and at least one of the meshes 34 is sealed at least in the surface direction. A plurality of stopped sealing portions 35 are provided. When the frequency of the intervals between the sealing portions 35 is converted, the plurality of sealing portions 35 increase in frequency as the frequency decreases, and are −0.6 power or less and −1.4 power or more of the frequency. It is formed by arrangement.

  The supply gas flow path member 30 is not particularly limited as long as it allows gas to pass therethrough, but may be formed by weaving the yarns 31 and 32 as warp yarns and weft yarns (see FIGS. 5 and 6). ) Alternatively, the resin monofilament yarns 31 and 32 may be overlapped in a lattice pattern, and the intersections may be fused (see FIGS. 3 and 4) to weave one or more yarns. You may form by. According to these methods, a grid-like (mesh-like) flow path member is formed. A flow path member having a network structure is formed by forming wefts and warps as filaments even when resin is extruded from the nozzle of an extruder, arranged so as to intersect each other, and fusing the intersections of the threads by thermocompression bonding or the like. The method to obtain is preferable from the viewpoint that it is simple and easy to control the crossing angle with the weft and the warp, the area of the eyes (openings) formed by the crossing of the yarns, and the like.

  3 is an enlarged plan view of the supply gas flow path member 30 of the present embodiment, and FIG. 4 is a cross-sectional view of the supply gas flow path member of FIG. The supply gas flow path member shown in FIGS. 3 and 4 is formed by crossing a weft 31 and a warp 32 and fusing the intersecting portion.

  5 and 6 are a partially enlarged plan view and a cross-sectional view showing another example of a supply gas flow path member. As shown in FIGS. 5 and 6, it is also possible to use a mesh structure in which wefts 31 and warps 32 are woven and alternately turned up and down at intersections.

  The yarn constituting the supply gas flow path member 30 may be a monofilament or a twisted yarn. Since the module according to the present invention is basically used under a temperature condition of 100 ° C. or higher, for example, about 130 ° C. and under a high humidity condition, the material constituting the yarn is heat resistant. A material that does not have water absorption is preferably used.

  Specifically, the material of the yarn is selected from, for example, polyester, polypropylene, polyamide, polyphenylene sulfide, polysulfone, polytetrafluoroethylene, polyether ether ketone, polyvinyl chloride, polyether sulfone, polycarbonate, and polyvinylidene fluoride. Those containing at least one kind of resin are preferable, and one or more kinds of resins selected from polypropylene, polytetrafluoroethylene, polysulfone, and polyethersulfone are more preferable.

  Moreover, as a preferable material from a heat-and-moisture resistant viewpoint, you may use inorganic materials, such as a ceramic, glass, and a metal.

  The average diameter b of the yarns 31 and 32 is 15 μm or more and 1000 μm or less, preferably 100 μm or more and 500 μm or less.

  The average diameter b of the yarn constituting the net is the arithmetic average value of ten yarn diameters measured in the region excluding the vicinity of the intersection of the yarn and the vicinity of the point where the base is fused to each other. .

  When measuring the diameter of the yarn, if the cross section of the yarn is circular, the diameter is adopted, and if the shape of the yarn is a different diameter cross section or a flat cross section, in the luck to be measured, with respect to the thickness direction of the flow path member The passing length of the yarn is the diameter of the yarn. The diameter of the thread may be measured directly using a caliper or the like, or may be measured visually while magnifying with a magnifying glass or the like, and a photograph of the cross section of the flow path member is taken to determine the diameter of the thread in the image. You may measure.

  The thickness t of the flow path member can be measured using a thickness measuring instrument used for cloth or the like if the mesh structure is fine (for example, the opening area is 1 mm 2 or less). . In this case, the measured value itself is the thickness t of the flow path member 30. In addition, when the opening area is large, the thickness measuring device described above may be used, for example, when the thickness of the crossing portion of the yarn is remarkably thick, or when the thickness of the crossing portion of the yarn is remarkably thick compared to the surrounding thickness. If accurate film thickness measurement is difficult, the thickness of the crossing part of the thread and the part where the thread is fused are visually measured while enlarged with a caliper or loupe. It is defined as thickness t. Again, the thickness t employs an arithmetic average value obtained by measuring 10 different points in the flow path member 30.

  As shown in FIGS. 4 and 6, the thickness t of the flow path member 30 is not more than twice the diameter b of the yarn and preferably less than twice.

Area of the eye (opening) 34 formed by the network structure of the flow path member 30 is permeable membrane 10 that is positioned adjacent the viewpoint from 0.5 mm ² or more that hardly intrudes into the gap, is 20 mm ² It is more preferable that it is 0.7 mm ² or more and 15 mm ² or less. The mesh size is preferably 30 μm or more and 2000 μm or less. The opening area of the mesh structure in plan view can be easily adjusted by controlling the conditions for knitting and weaving the threads 31 and 32, the conditions for crossing the threads before fusing, and the like.

  Since the flow path of the fluid changes depending on the shape of the mesh structure of the flow path member, the shape of the unit cell of the mesh structure is appropriately selected from shapes such as rhombus and parallelogram according to the purpose. .

  The sealing portion 35 seals at least one of the net eyes 34 in at least the surface direction. The area of one sealing portion 35 in a plan view of the net is such that it fills one net eye (opening) 34 and may have a size that fills two or more net eyes 34 continuously. However, it is preferable that the size of one sealing portion 35 is about 2 to 3 because it does not greatly hinder the main flow of the supply gas described later. One sealing portion 35 has a continuous surface, and the portions connected by points are counted as separate sealing portions, but the sealing portions 35 are preferably separated from each other. The ratio of the sealing portion 35 to the opening area in the net plan view is preferably 1/10 or less and 1/100 or more.

  The thickness a of the sealing portion 35 may not exceed the net thickness t. If the thickness t of the net is not exceeded, damage to the separation membrane that comes into contact with the net can be suppressed. The thickness a of the sealing part 35 is more preferably 0.1 t or more and 0.9 t or less.

  As for the thickness a of the sealing part 35, 10 points are measured and set as the average. It may be measured directly using a caliper or the like, or it may be measured visually while enlarging a photograph of the cross section of the sealing portion 35 with a magnifying glass or the like, or a photograph of a cross section of the sealing portion 35 may be taken. You may measure the thickness of the sealing part in an image.

  When the frequency of the interval between the sealing portions 35 is frequency-converted, the plurality of sealing portions 35 are arranged such that the frequency increases with a decrease in frequency, which is −0.6 power or less and −1.4 power or more of the frequency f. It is formed with. In particular, the frequency (power spectrum) is preferably inversely proportional to the frequency f. In general, 1 / f noise refers to noise that is proportional to f raised from the power of −0.8 to the power of −1.2, and this range is more preferable. It is 1 / f when the multiplier is -1.

  Here, increasing the frequency with a decrease in frequency means that the gaps between the sealing portions are often large, and those with a small gap are arranged to be small. By setting it as such an arrangement | positioning, generation | occurrence | production of condensed water is suppressed and the module by which the pressure loss was suppressed can be obtained. Note that the region where the sealing portion having such an arrangement is formed preferably extends over the entire effective gas flow path of the supply gas flow path member of the module. Since the generation of the condensed water and the pressure loss can be suppressed in the part, the effect of the present invention is exhibited. In addition, although it is conceivable that an adhesive portion is formed at the end of the supply gas flow path member for temporarily fixing the supply gas flow path member, it is not related to the main flow of the supply gas at the end. The adhesion part formed in the part is not the sealing part of the present invention.

  By arranging the sealing portions as described above, the generation of turbulence is promoted where the interval between the sealing portions is small, and the outlet of the residual gas 24 from the flow channel inlet side of the supply gas 20 where the interval is large. Since the flow path can be secured so as not to obstruct the large flow toward the side (the flow from left to right in FIG. 2) more than necessary, as a result, the generation of condensed water can be suppressed and the separation efficiency can be improved. At the same time, it is considered that the pressure loss increase width can be suppressed. It seems that the mixing effect (turbulence promotion effect) and the local pressure increase at the intersection or the sealing part are in a trade-off relationship. This range is estimated to be a range in which it is possible to balance the suppression of this pressure increase (that is, the generation of condensed water) and the promotion of permeation of acidic gas to the separation membrane by turbulent flow.

Whether or not the arrangement of the supply gas flow path member 30 in which the sealing portion 35 is formed is within the scope of the present invention is determined by frequency-converting the interval between the sealing portions as follows. This can be confirmed by obtaining the relationship.
1) An arbitrary sealing portion (hereinafter referred to as a reference sealing portion) is determined. Here, the reference point of the sealing portion is the center of gravity of the sealing area. In FIG. 2, the sealing portion 35 of row r ₀ and column c ₀ is used as a reference point.
2) before and after the reference seal portion (r _-100 ~r ₁₀₀ in the row direction), lateral (column c _-100 to c ₁₀₀₎ to 100 mesh fraction, a central or reference point (r _0, c ₀ 200 intervals for total sealing portion disposed in a mesh square _L i (i = _1~n, n is the total number of sealing portions of the front and rear 100 within the mesh) is measured. in FIG. 2, r ₀ line, c ₀ column The intervals L ₁ , L ₂ , L ₃ ,..., L _n between the reference sealing portion and the other sealing portions are measured using the sealing portion 35 as a reference point.
3) Perform FFT (Fast Fourier Transform) based on L _{1 to} L _n . The FFT can be executed using, for example, Microsoft Excel.
4) Define 200 meshes as one period, convert the interval to frequency, obtain a power spectrum, normalize the spectrum intensity, and convert it to the relationship between frequency and frequency.

  As described above, the relationship between frequency and frequency can be obtained.

  Any material can be used as the material for the sealing portion 35 as long as it blocks the flow of gas. Epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, thermosetting polyimide Etc.

  The sealing part 35 can be formed by dropping a sealing material prepared to have a viscosity of about 0.01 Pa · s to 10 Pa · s into the opening of the flow path member and curing it. The arrangement of the sealing part 35 is based on, for example, creating a signal having 1 / f fluctuation by a fluctuation signal generating device described in JP 2002-7379 A, JP 2011-250060 A, or the like. decide.

  The thickness a of the sealing portion 35 can be set to a desired thickness by adjusting the amount of dripping with respect to the volume of the opening 34 (opening area × channel member thickness).

  Hereinafter, components other than the supply gas flow path member 30 constituting the acidic gas separation spiral-type module 100 will be described.

  As shown in FIG. The permeate gas collecting pipe 12 is a cylindrical pipe having a plurality of through holes 12A formed in the pipe wall. The one end side (one end 100A side) of the permeate gas collecting pipe 12 is closed, the other end side (the other end 100B side) of the permeate gas collecting pipe 12 is opened, and the carbon dioxide collects from the through hole 12A through the laminate. A discharge port 26 from which acidic gas 22 such as gas is discharged is provided.

  The covering layer 16 is formed of a blocking material capable of blocking the raw material gas 20 passing through the acidic gas separation module 100. It is preferable that the barrier material has heat and humidity resistance.

<Laminate>
In the laminated body 14, the supply gas flow path member 30 is sandwiched inside the acid gas separation membrane 10 folded in half, and the acid gas separation film 10 is attached to the permeate gas flow path member 6 on the inner side in the radial direction. It is configured to be sealed through a sealing portion (not shown in FIG. 1) penetrating these.

  The number of the laminated body 14 wound around the permeate gas collecting pipe 12 is not particularly limited, and may be single or plural. By increasing the number (number of laminated layers), the membrane area of the facilitated transport film can be improved. it can. Thereby, the quantity which can isolate | separate the acidic gas 22 with one module can be improved. Moreover, in order to improve a film area, you may make the length of the laminated body 14 longer.

  Moreover, when there are a plurality of laminates 14, the number is preferably 50 or less, more preferably 45 or less, and even more preferably 40 or less. When the number is less than or equal to the number, it is easy to wind the laminate 14 and the workability is improved.

  Although the width | variety of the laminated body 14 is not specifically limited, It is preferable that they are 50 mm or more and 10,000 mm or less, More preferably, they are 60 mm or more and 9000 mm or less, Furthermore, it is preferable that they are 70 mm or more and 8000 mm or less. Furthermore, it is preferable that the width | variety of the laminated body 14 is 200 mm or more and 2000 mm or less from a practical viewpoint. By setting it to each lower limit value or more, an effective area of the acidic gas separation membrane 10 can be secured even when resin is applied (sealed). Moreover, by setting it as each upper limit value or less, the horizontality of the winding core can be maintained and the occurrence of winding deviation can be suppressed.

  In this configuration, the raw material gas 20 including the acidic gas 22 is supplied from the end of the supply gas flow path member 30, and the acidic gas 22 that has been separated through the acidic gas separation membrane 10 is used for the permeated gas flow path. The gas is collected in the permeate gas collecting pipe 12 through the member 6 and the through-hole 12 </ b> A, and is collected from the discharge port 26 connected to the permeated gas collecting pipe 12. The residual gas 24 separated from the acid gas 22 that has passed through the gap or the like of the supply gas flow path member 30 is supplied to the supply gas flow path on the side where the discharge port 26 is provided in the acidic gas separation module 100. It is discharged from the end of the member 30.

(Acid gas separation membrane 10)
The acidic gas separation membrane 10 is composed of a porous support and an acidic gas separation facilitated transport membrane (hereinafter referred to as a facilitated transport membrane) that is supported by the porous support and contains at least a hydrophilic compound and an acidic gas carrier. It is comprised with the composite_body | complex and is arrange | positioned so that a facilitated-transport film | membrane may face the member for supply gas flow paths.

((Acid gas carrier))
The acid gas carrier refers to a substance that reacts indirectly with the acid gas or a substance that itself reacts directly with the acid gas. Indirect reaction with an acid gas includes, for example, a reaction with another gas contained in the supply gas, showing basicity, and a reaction between the basic compound and the acid gas. As this type of acid gas carrier, and more specifically, by reacting with steam OH ^- to the release, the OH ^- can be incorporated selectively CO ₂ in the film by reacting with CO ₂ Such alkali metal compounds are mentioned.

  Examples of the acid gas carrier that directly reacts with the acid gas include basic compounds such as nitrogen-containing compounds and sulfur oxides.

  Examples of the alkali metal compound include at least one selected from the group consisting of an alkali metal carbonate, an alkali metal bicarbonate, and an alkali metal hydroxide, and a polydentate that forms a complex with an alkali metal ion in an aqueous solution containing the alkali metal compound. Examples include aqueous solutions to which a ligand is added, ammonia, ammonium salts, various linear and cyclic amines, amine salts, ammonium salts, and the like. These water-soluble derivatives can also be preferably used. Since carriers that can be retained in the facilitated transport film for a long period of time are useful, amine-containing compounds that are difficult to evaporate, such as amino acids and betaines, are particularly preferred.

  In addition, in this specification, an alkali metal compound is used in the meaning containing the salt and its ion other than alkali metal itself.

  Examples of the alkali metal carbonate include lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, and cesium carbonate.

  Examples of the alkali metal bicarbonate include lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, rubidium hydrogen carbonate, and cesium hydrogen carbonate.

  Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

  Among these, an alkali metal carbonate is preferable, and a compound containing potassium, rubidium, and cesium having high solubility in water as an alkali metal element is preferable from the viewpoint of good affinity with an acidic gas.

  Here, in this embodiment, since the hygroscopic facilitated transport membrane is used as the carbon dioxide gas separation membrane, the facilitated transport membrane becomes a gel due to moisture absorbed during production, and the facilitated transport membrane is formed between the membranes and other membranes during production. The phenomenon of sticking to the member (blocking) is likely to occur. When this blocking occurs, when the facilitated transport film is peeled off, the facilitated transport film may cause defects due to the sticking, resulting in gas leakage. Therefore, in this embodiment, it is preferable to prevent blocking.

  Therefore, in this embodiment, the carrier preferably contains two or more alkali metal compounds. This is because, by using two or more kinds of carriers, blocking of the same kind of carriers in the film can be created by creating a non-uniformity of blocking by separating the distances.

  Furthermore, it is more preferable that the carrier contains a first alkali metal compound having deliquescence and a second alkali metal compound having a lower deliquescence and a lower specific gravity than the first alkali metal compound. Specifically, the first alkali metal compound includes cesium carbonate, and the second alkali metal compound includes potassium carbonate.

  Since the carrier contains the first alkali metal compound and the second alkali metal compound, the second alkali metal compound having a small specific gravity is arranged on the film surface side of the facilitated transport film (that is, unevenly disposed on the surface side of the facilitated transport film). The first alkali metal compound having a large specific gravity is disposed inside the facilitated transport membrane (that is, unevenly disposed on the porous support side of the facilitated transport membrane). And since the 2nd alkali metal compound arrange | positioned at the film surface side has lower deliquescence property than a 1st alkali metal compound, compared with the case where a 1st alkali metal compound is arrange | positioned at the film surface side, a film surface is sticky. Therefore, blocking can be suppressed. In addition, since the first alkali metal compound having high deliquescence is disposed inside the membrane, blocking is suppressed and the separation efficiency of carbon dioxide gas is reduced as compared with the case where the second alkali metal compound is simply disposed over the entire membrane. Can be increased.

  Specifically, in the acidic gas separation membrane 10, when two or more kinds of alkali metal compounds (first and second alkali metal compounds) are applied as carriers, the facilitated transport membrane is a surface opposite to the porous support. The second layer on the side and the first layer on the porous support side below the second layer. The facilitated transport film is entirely composed of a hydrophilic compound (hydrophilic polymer), and among them, the second layer mainly contains a second alkali metal compound having low deliquescence and low specific gravity. Yes. In the first layer, a first alkali metal compound having mainly deliquescence exists. The thickness of the second layer is not particularly limited, but is preferably 0.01 to 150 μm and more preferably 0.1 to 100 μm in order to exhibit a sufficient deliquescent function.

  In the facilitated transport film, the second layer containing the second alkali metal compound is unevenly distributed on the surface side, and the first layer containing the first alkali metal compound is spread below the second layer, but the embodiment is limited to this. It is not a thing. For example, the interface between the two layers may not be clear, and the two layers may be separated in a state in which both change in an inclined manner. Further, the interface is not constant and may be in a meandering state.

  The deliquescence of the membrane is suppressed by the action of the second layer containing the second alkali metal compound having low deliquescence and low specific gravity. The reason why the second alkali metal compound is unevenly distributed is considered to be due to the difference in specific gravity between two or more alkali metals. That is, by setting one of two or more types of alkali metals to a low specific gravity, it is possible to localize a lighter specific gravity in the coating solution at the time of film formation. Then, while maintaining the high transport force such as carbon dioxide of the first alkali metal compound having the deliquescence contained in the first layer inside the film, the surface of the second layer film is more crystalline than the second alkali metal compound has. Condensation and the like can be prevented due to the property of being easily converted. Thereby, while blocking can be suppressed, the separation efficiency of a carbon dioxide gas can be improved.

  Since the second alkali metal compound only needs to be on the film surface side in order to suppress blocking, the second alkali metal compound is preferably contained in a smaller amount than the first alkali metal compound. Thereby, the amount of the first alkali metal compound having high deliquescence is relatively large in the entire membrane, and the carbon dioxide separation efficiency can be further increased.

  Here, the number of types of two or more types of alkali metal compounds is determined by the type of alkali metal, and even if the counter ions are different, it is not counted as one type. That is, even if potassium carbonate and potassium hydroxide are used in combination, it is counted as one type.

As a combination of two or more kinds of alkali metal compounds, those shown in Table 1 below are preferable. In Table 1, an alkali metal compound is indicated by the name of an alkali metal, but it may mean a salt or ion thereof.

  The content of the entire carrier in the hydrophilic compound layer depends on the type of the carrier, but in order to prevent salting out before coating and to reliably exhibit the function of separating acidic gas, it is 0.3 to 80% by mass. It is preferable that it is 0.5 to 70% by mass, more preferably 1 to 65% by mass.

  When two or more kinds of alkali metal compounds are applied as the carrier, the content of the two or more kinds of alkali metal compounds is the total solid content of the hydrophilic compound and two or more kinds of alkali metal compounds that are the main components of the film. In terms of mass, the mass ratio of two or more alkali metal compounds is preferably 25% by mass or more and 85% by mass or less, and more preferably 30% by mass or more and 80% by mass or less. By setting this amount within the above range, the gas separation function can be sufficiently exhibited.

  Of the two or more types of alkali metal compounds, the second alkali metal compound (alkali metal compound unevenly distributed on the surface side of the facilitated transport film) having a lower deliquescence and a lower specific gravity than the first alkali metal compound is a hydrophilic compound and 2 It is preferably 0.01% by mass or more, and preferably 0.02% by mass or more, based on the total mass (typically, the total mass of the separated layer after drying) of the solid content of the alkali metal compound or more of the seeds. More preferably. Although there is no upper limit in particular, it is preferable that it is 10 mass% or less, and it is more preferable that it is 7.5 mass% or less. If this amount is too small, blocking may not be prevented, and if it is too large, handling may not be possible.

  The ratio of the second alkali metal compound to the first alkali metal compound is not particularly limited, but the first alkali metal compound is preferably 50 parts by mass or more and 100 parts by mass or more with respect to 100 parts by mass of the second alkali metal compound. More preferred. As an upper limit, 100000 mass parts or less are preferable, and 80000 mass parts or less are more preferable. By adjusting the ratio of the two in this range, it is possible to achieve both blocking properties and handling properties at a high level.

  Examples of nitrogen-containing compounds include amino acids such as glycine, alanine, serine, proline, histidine, taurine, and diaminopropionic acid, hetero compounds such as pyridine, histidine, piperazine, imidazole, and triazine, monoethanolamine, diethanolamine, and triazine. Alkanolamines such as ethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, cyclic polyetheramines such as cryptand [2.1] and cryptand [2.2], cryptand [2.2.1] Bicyclic polyetheramines such as cryptand [2.2.2], porphyrin, phthalocyanine, ethylenediaminetetraacetic acid and the like can be used.

  As the sulfur compound, for example, amino acids such as cystine and cysteine, polythiophene, dodecylthiol and the like can be used.

((Hydrophilic compound))
The hydrophilic compound functions as a binder, and retains water when used for the facilitated transport film to exert the function of separating the acidic gas by the acidic gas carrier. The hydrophilic compound is preferably highly hydrophilic from the viewpoint that it can be dissolved in water or dispersed in water to form a coating solution, and the facilitated transport film has high hydrophilicity (moisturizing property). A compound that absorbs water having a mass of 5 to 1000 times the mass of the hydrophilic compound itself is preferable.

  Examples of the hydrophilic compound include, for example, agar, polyvinyl alcohol-polyacrylate, polyvinyl alcohol-polyacrylic acid (PVAPAA) copolymer, polyvinyl alcohol, polyacrylic, from the viewpoint of hydrophilicity, film-forming property, strength, and the like. Hydrophilic polymers such as acids, polyacrylates, polyvinyl butyral, poly-N-vinyl pyrrolidone, poly-N-nylacetamide, and polyacrylamide are preferred, and PVA-PAA copolymers are particularly preferred. The PVA-PAA copolymer has a high water absorption capacity and a high hydrogel strength even at high water absorption. The content of the polyacrylate in the PVAPAA copolymer is preferably, for example, from 5 mol% to 95 mol%, and more preferably from 30 mol% to 70 mol%. Examples of polyacrylic acid salts include alkali metal salts such as sodium salt and potassium salt, as well as ammonium salts and organic ammonium salts.

  Examples of commercially available PVA-PAA copolymers include Clastomer-AP20 (trade name: manufactured by Kuraray Co., Ltd.).

  The content of the acidic gas carrier in the facilitated transport film depends on the ratio to the amount of the hydrophilic compound and the type of the acidic gas carrier, but functions as an acidic gas carrier and the acidic gas in the use environment. From the viewpoint of excellent stability as a separation layer, it is preferably 0.1% by mass or more and 80% by mass or less, more preferably 0.2% by mass or more and 70% by mass or less, and further 0.3% by mass. % To 65% by mass is particularly preferable.

  The facilitated transport membrane may contain other components (additives) other than the hydrophilic compound, the acidic gas carrier, and water as long as the separation characteristics are not adversely affected. As an optional component, for example, a coating liquid film containing a hydrophilic compound and an acidic gas carrier is coated on a porous support and dried in the course of drying. A gelling agent that controls the so-called set property, a viscosity adjusting agent that adjusts the viscosity at the time of coating when the coating solution is coated with a coating device, a crosslinking agent for improving the film strength of the facilitated transport film, Acid gas absorption promoters, other surfactants, catalysts, auxiliary solvents, membrane strength modifiers, and detection agents for facilitating the inspection of the formed acid gas separation layer for defects. .

  The average thickness of the facilitated transport membrane is preferably 1 μm or more and 200 μm or less, more preferably 3 μm or more and 150 μm or less, and particularly preferably 5 μm or more and 120 μm or less from the viewpoint that an acid gas separation layer having excellent performance can be obtained.

((Porous support))
The support supports the acidic gas separation-enhanced transport membrane, has an acid gas permeability, and is formed by applying an acid gas separation-enhanced transport membrane forming composition (coating liquid). There is no particular limitation as long as it can support the membrane.

  Suitable materials for the support include paper, fine paper, coated paper, cast coated paper, synthetic paper, and cellulose, polyester, polyolefin, polyamide, polyimide, polysulfone aramid, polycarbonate, metal, glass, ceramics, etc. it can. More specifically, resin materials such as polypropylene, polyethylene, polystyrene, polyphenyl sulfide, polyether imide, polyether ether ketone, polysulfone, polyether sulfone, polyethylene terephthalate, polytetrafluoroethylene, and polyvinylidene fluoride are preferable. Can be used. Among these, polyolefins and fluorides thereof can be particularly preferably used from the viewpoint of stability over time.

  As the form of the support, a woven fabric, a non-woven fabric, a porous membrane or the like can be adopted. In general, a support having a high self-supporting property and a high porosity can be suitably used. Polysulfone, cellulose membrane filter membrane, polyamide, polyimide interfacially polymerized thin film, polytetrafluoroethylene, high molecular weight polyethylene stretched porous membrane has high porosity, low acid gas diffusion inhibition, strength, suitability for manufacturing, etc. To preferred. Among these, a stretched film of polytetrafluoroethylene (PTFE) is particularly preferable.

  These supports can be used alone, but a composite membrane integrated with a support for reinforcement can also be suitably used.

  As the support, it is particularly preferable to use a laminated film of a hydrophobic porous film and a nonwoven fabric as an auxiliary support film. Since the mechanical strength can be improved by providing an auxiliary support film, there is an effect that the support film does not wrinkle even when handled in a roll-to-roll coating apparatus, and productivity can also be improved. . In this case, it is particularly preferable to use PTFE as the hydrophobic porous film and polypropylene (PP) which is inexpensive and has high mechanical strength as the nonwoven fabric.

  The hydrophobic porous membrane means that the surface of the porous membrane on the side in contact with the facilitated transport membrane is a hydrophobic surface. If the surface is hydrophilic, the facilitated transport film containing moisture in the use environment is likely to penetrate into the porous portion, and there is a concern that the film thickness distribution and performance deterioration with time may occur. Here, the term “hydrophobic” means that the contact angle of water at room temperature (25 ° C.) is about 80 ° or more.

  If the support is too thick, the gas permeability decreases, and if it is too thin, the strength is difficult. Therefore, the thickness of the support is preferably 30 to 500 μm, more preferably 50 to 300 μm, and even more preferably 50 to 200 μm. Further, for example, the Young's modulus of the support is preferably 0.4 GPa or more so that the support is not distorted or broken in the production of Roll-to-Roll. When the support is a laminated film of a porous film and a nonwoven fabric, the porous film thickness is preferably about 5 to 100 μm, and the nonwoven film thickness is preferably about 50 to 300 μm.

(Permeate gas channel member)
The permeating gas channel member 6 is a member that reacts with the carrier and the acidic gas that has permeated the acidic gas separation membrane 10 flows toward the through hole. The permeate gas flow path member 6 has a function as a spacer, and also has a function of causing the permeated acidic gas to flow inside the permeate gas flow path member 6. An example is a tricot knitting shape. The material of the permeating gas flow path member can be the same as that of the supply gas flow path member. In addition, assuming that a raw material gas containing water vapor is flowed at a high temperature, it is preferable that the permeate gas channel member has moisture and heat resistance in the same manner as the acidic gas separation membrane.

  Specific materials used for the permeating gas channel member are preferably polyesters such as epoxy-impregnated polyester, polyolefins such as polypropylene, and fluorines such as polytetrafluoroethylene.

  The thickness of the permeating gas channel member is not particularly limited, but is preferably 100 μm or more and 1000 μm or less, more preferably 150 μm or more and 950 μm or less, and further preferably 200 μm or more and 900 μm or less.

  Examples of the present invention and comparative examples will be described.

<Preparation of separation membrane>
Clastomer AP-20 (manufactured by Kuraray Co., Ltd.): 2.4% by mass, 25% glutaraldehyde aqueous solution (manufactured by Wako): 1M hydrochloric acid was added to an aqueous solution containing 0.01% by mass until the pH reached 1.5. Thereafter, a 40% cesium carbonate aqueous solution (manufactured by Rare Metal Co., Ltd.) as a carrier was added so that the cesium carbonate concentration was 5.0% by mass to obtain a coating composition. By applying and drying this coating composition on the PTFE side using PTFE / PP nonwoven fabric (manufactured by GE) as a porous support, an acid gas comprising an acidic gas separation layer (facilitated transport membrane) and a porous support is provided. A separation membrane was prepared. This example is a separation membrane for carbon dioxide separation.

<Production of spiral type module>
The produced acidic gas separation membrane was folded in half with the facilitated transport membrane inside. Kapton tape was applied to the valley that was folded in half to reinforce the surface shape of the membrane valley. Then, a feed spacer of any of Examples 1 to 12 and Comparative Examples 1 to 5, which will be described later, was sandwiched between the two folded separation membranes as a supply gas flow path member to produce a leaf.

  Apply the adhesive to the porous support side of the prepared leaf so that it is enveloped, and layer the perforated gas flow passage made of tricot knitted epoxy impregnated polyester around the effective hollow central tube (permeate gas collecting tube) A module for acid gas separation was produced by wrapping around and multiplying the tension.

<Supply gas channel member (feed spacer)>
(Examples 1-5)
A mesh-shaped polypropylene net (manufactured by Delstar, one side of the opening rhombus (opening) 1.5 mm, thickness 500 μm) was used. Place this net on a glass substrate, drop an appropriate amount of an adhesive made of an epoxy resin with high viscosity (about 40 Pa · s) (Henkel Japan Co., Ltd .: E120HP) onto the eyes (openings) of multiple nets, Then, the glass plate was placed and smoothed, and then cured to form a sealing portion. At this time, the thickness t of the sealing portion was substantially the same as the net thickness. That is, t = 500 μm.

  The arrangement of the sealing part is an arrangement in which the frequency increases with a decrease in frequency, and the frequency (power spectrum) has a frequency f of −0.6 power (Example 1) and −0.8 power (Example 2). ), −1 power (Example 3), −1.2 power (Example 4), and −1.4 power (Example 5). The total area of the sealing part with respect to the opening area in the range where the sealing part was formed with the above arrangement was 1/10.

(Example 6)
In Example 1, the thickness of the sealing portion was set to half the net thickness (0.5 t). The thickness of the sealing part was adjusted by adjusting the dropping amount of the adhesive to an amount that is half of the net thickness and dropping it. In this case, the smoothing by the glass plate after dripping is not performed.

(Example 7)
In Example 3, the thickness of the sealing portion was set to half the net thickness as in Example 6.

(Example 8)
In Example 5, the thickness of the sealing portion was set to half of the net thickness as in Example 6.

Example 9
In Example 3, the total area of the sealing part with respect to the opening area in the range where the sealing part was formed was set to 1/5.

(Example 10)
In Example 3, the total area of the sealing part with respect to the opening area in the range where the sealing part was formed was 1/30.

(Example 11)
In Example 3, the total area of the sealing part with respect to the opening area in the range where the sealing part was formed was set to 1/100.

(Example 12)
In Example 3, the total area of the sealing part with respect to the opening area in the range where the sealing part was formed was 1/200.

(Comparative Example 1)
In Example 1, the arrangement of the sealing portion is an arrangement in which the frequency increases with a decrease in the frequency, but the frequency (power spectrum) is in an arrangement proportional to the −0.5 power of the frequency f.

(Comparative Example 2)
In Example 1, the arrangement of the sealing portion is an arrangement in which the frequency increases with a decrease in the frequency, but the frequency (power spectrum) is in an arrangement proportional to the −1.5th power of the frequency f.

(Comparative Example 3)
In Example 1, the arrangement | positioning of the sealing part was made into the random arrangement | positioning whose frequency does not increase with the fall of a frequency.

(Comparative Example 4)
In Example 1, the sealing part was arrange | positioned periodically.

(Comparative Example 5)
A feed spacer having a protrusion described in Patent Document 2 in FIG. 5 (c) of the prior art documents listed in the background section is manufactured, and a module is manufactured in the same manner as in the embodiment except that this is used. did. This comparative example does not have a sealing portion that is large enough to close the eyes of the net.

<Evaluation of spiral module>
The following evaluations were performed on the obtained spiral modules of Examples and Comparative Examples, and the results are shown in Table 2.

(Pressure loss test)
The flow path member having a mesh structure was set in a parallel plate cell (flow path width: 10 cm, flow path length: 10 cm), and pressure loss (pressure loss) was measured when Air was flowed at a flow rate of 10 L / min.
The pressure loss was evaluated as good (A) at 9.8 kPa or less, acceptable (B) above 9.8 kPa, acceptable (B) at 10.1 kPa or less, and defective (C) at above 10.1 kPa.

(Gas separation performance)
The gas separation performance using the carbon dioxide separation module according to each of the examples and comparative examples was evaluated under the following conditions.
A source gas (flow rate: 2.2 L / min) of H ₂ : CO ₂ : H ₂ O = 45: 5: 50 is supplied as a test gas to each module at a temperature of 130 ° C. and a total pressure of 301.3 kPa, and Ar is placed on the permeate side. Gas (flow rate 0.6 L / min) was allowed to flow. The permeated gas was analyzed with a gas chromatograph, and the CO ₂ permeation rate was calculated.

  The permeation rate was measured after the module production of each example and comparative example, at the initial stage, and after 100 hours of use.

  The initial transmission rate was evaluated as good (A) at 22.0 or more (A), less than 22.0, acceptable (B) at 21.0 or more (B), and poor (C) at less than 21.0.

  Durability is good if the difference between the initial transmission rate and the transmission rate after 100 hours of operation is 5% or less (A), more than 5%, 10% or less (B), more than 10% or poor pressure drop ( C).

  The module evaluation is a comprehensive judgment of pressure loss evaluation, permeation speed evaluation, and durability evaluation. If any of them has a defect (C), it is defective (C) as a module, and only (B) is acceptable or good. When (A) is 1, it is possible to be a module (B), when A is 2 and B is 1, it is judged as good (A), and when A is 3, it is judged as good (A +).

As shown in the evaluation results, it was found that the durability is improved as compared with the comparative example by arranging the sealing portion so that the frequency increases as the frequency decreases. This is because the arrangement of the sealing portion is such that the frequency increases as the frequency decreases, so that the water vapor in the supply gas is moderately agitated and does not easily deposit as water droplets on the film surface. It is thought that it was because of.
At that time, the pressure loss was the smallest and the initial transmission speed was increased when the frequency was in the vicinity of the -1.0 power of the frequency f. By setting the thickness of the sealing part to 0.5 t, the pressure loss and the initial transmission rate also increased.

6 Permeate Gas Channel Member 10 Acid Gas Separation Membrane 12 Permeate Gas Collecting Tube 14, Acid Gas Separation Laminate 20 Raw Material Gas (Supply Gas)
22 Acid gas (permeate gas)
24 Residual gas 30 Supply gas channel member 31, 32 Thread 34 Eye (opening)
35 Sealing part 100 Spiral acid gas separation module

Claims (2)

The acidic gas separation membrane, the supply gas flow path member and the permeate gas flow path member are a spiral type module for acidic gas separation wound around a perforated hollow central tube,
The supply gas flow path member is composed of a net formed by crossing a plurality of yarns in a lattice pattern,
At least one of the eyes of the net has a plurality of sealing portions sealed at least in the surface direction,
When the plurality of sealing portions are frequency-converted between the sealing portions, the frequency increases with a decrease in frequency. A spiral-type module for acid gas separation, characterized in that it is formed of The sealing unit according to claim 1 acid gas separation spiral module according thickness d _c is equal to or less than the net thickness d _n of.