JP2007222841A - Pleat element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-separating module which gives a low pressure-loss, improves handleability, and is particularly suitable for a nitrogen-rich air feeding device for an internal combustion engine, and also provide a manufacturing method thereof. <P>SOLUTION: A pleat element is composed of; two pleat moldings comprising gas-separating membranes and air-permeable reinforcement materials; and a reinforcement frame. In addition, the two-dimensional side flow channel of the pleat is sealed at its both ends to form an envelope-like structure. The pleat moldings are arranged so that their one-dimensional side pleat faces may be opposite and adjacent to each other, and the reinforcement frame adheres firmly to a sealing means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a box pleat element used in a gas separation module.

The separation operation using a membrane is advantageous in that the equipment is simpler and the operation cost is lower than the separation operation such as distillation and adsorption, and it is widely used particularly in liquid processing. On the other hand, gas treatment with membranes can be broadly classified into air filters and gas separation membranes, but at present, the former occupies the majority and the latter has not yet formed a large market. That is, at present, large industrial equipment such as hydrogen recovery at ammonia plants and volatile organic compound recovery at gasoline depots are mainly used, and small consumer equipment is partially used due to problems such as processing capacity and ventilation resistance. Practical use is delayed except for small devices (medical and oxygen air conditioners). As a condition required for a small apparatus for gas separation,
1) Membrane area 2) Ventilation resistance 3) Durability 4) The production cost can be increased. Among these, the ventilation resistance is not a big problem in a large apparatus with a sufficient supply pressure of gas, but it tends to be a problem particularly in a small apparatus having a limited use environment while aiming at a small high flow treatment.

  The gas separation module serving as the core of the gas separation device includes 1) a so-called “hollow fiber module” in which both ends of a hollow fiber membrane bundle made of a polymer material excellent in gas permeability are sealed and accommodated in a cylindrical housing. Is widely used (Patent Document 1). 2) After forming a pair of flat membranes made of a polymer material with excellent gas permeability into an envelope shape, wind the envelope with the open end of the envelope attached to the center pipe and finally sealing both ends. Next, a so-called “spiral module” housed in a cylindrical housing is used (Patent Document 2). Furthermore, 3) a small number of so-called “plate and frame modules” are used in which a flat membrane made of a polymer material having excellent gas permeability is fixed to a frame and laminated as necessary (Non-patent Document 1).

In addition to the above, in the liquid processing apparatus, 4) pleating that can be seen in curtains and skirts by repeating a mountain fold and a valley fold at a specific pitch on a flat film made of a polymer material with excellent gas permeability. After applying, so-called `` cylindrical pleat module '' is used, in which the pleated surfaces at both ends are adhered to each other to arrange the whole into a cylindrical shape, and finally both ends of the cylinder are sealed and inserted into a cylindrical housing, There is almost no application to a gas separation device (Patent Document 3).
Among these, since the hollow fiber module has a large membrane area per volume, the spiral module can accommodate a relatively inexpensive flat membrane at a relatively high density, and is therefore suitable for a large apparatus requiring a large area. However, all modules except 3) are “tubular modules” using a cylindrical housing, and are essentially pressure loss due to their small cross-sectional area and long depth (parallel to the cylindrical centerline). There was a drawback that was large. These disadvantages can be improved, for example, by increasing the cross-sectional area of the module and shortening the depth. However, it is actually difficult to arrange a large number of short hollow fiber membranes while bundling a small number of long hollow fiber membranes. It was also difficult to shorten the length and increase the number of windings in terms of winding misalignment and ventilation resistance. For the above reasons, the cylindrical module cannot be said to be a module shape suitable for a small apparatus for gas separation intended for small high flow treatment.

As a result of studying the above problems, the present inventors have found that a box pleat module is suitable for gas separation (Patent Document 4, Patent Document 5), and then a specific box pleat module uses a non-permeating gas. It was found that it is more suitable for a system (for example, a nitrogen-enriched air supply device) (Patent Document 6). However, even this box pleated module is currently required to be further improved. Then, after explaining the apparatus about the improvement request | requirement about a nitrogen-enriched air supply apparatus, it shows concretely below.

[Nitrogen-enriched air supply device for internal combustion engine]
An internal combustion engine is widely used in an automobile engine, but has a feature that nitrogen and oxygen react to generate and discharge nitrogen oxide (NOx) as is well known when the combustion temperature becomes high. As a nitrogen oxide (NOx) removal system, a gasoline engine uses a three-way catalyst that simultaneously removes hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in exhaust gas by oxidation and reduction reactions. Although effective, in diesel engines, it has been a problem that the three-way catalyst does not function effectively due to the difference in oxygen concentration in the exhaust gas.

As a nitrogen oxide (NOx) removal system that works on diesel engines,
1) Effective reduction catalyst even in the presence of oxygen (urea SCR system, LNT catalyst system)
2) Reduction of oxygen concentration inside the engine (EGR exhaust gas recirculation system)
Etc. are already known. Of these, the urea SCR system has already been partially put into practical use, but in addition to the need for expensive catalysts, urea water injection devices, anti-freezing devices, etc., all of the generated nitrogen oxides (NOx) are removed. To do this, it is necessary to install a large urea water tank as well as a fuel tank. Although the LNT catalyst system can remove nitrogen oxides without adding a reducing agent such as urea water, there are problems such as a narrow operating range and large catalyst deterioration. Among the above, EGR is most widely used, but there are problems such as requiring an intermediate cooling device, and recharging is difficult because the supercharging pressure becomes higher than the exhaust pressure at high loads. That is, all of the current nitrogen oxide removal systems have drawbacks, and the development of more effective nitrogen oxide removal systems is significant as diesel engines are attracting attention from the viewpoint of energy saving and carbon dioxide (CO ² ) emission reduction. It has become a challenge.

  In recent years, attempts have been made to reduce the oxygen concentration inside the engine by a method different from exhaust gas recirculation by using a gas separation membrane (Non-Patent Document 2). Such a device is referred to as a nitrogen-enriched air supply device, and a gas separation module serving as the core thereof is referred to as a nitrogen-enriched module. According to this document, pressurized air introduced from a turbocharger is supplied to a supply port of a gas separation module having a hollow fiber membrane having oxygen selective permeability, and oxygen-enriched air is supplied to the secondary side of the hollow fiber module. A method is disclosed in which nitrogen-enriched air is taken out from a non-permeating port while being permeated and removed and supplied to an engine. Since the oxygen concentration of nitrogen-enriched air taken out from the gas separation module is 16 to 20%, which is comparable to the oxygen concentration when EGR is performed (Non-Patent Document 3), both have the same combustion temperature reduction function. It is thought to show. In addition, since the performance of the gas separation module is improved as the supercharging pressure is increased, the gas separation module has a complementary relationship with EGR that is less likely to function effectively as the supercharging pressure is increased.

  The box pleat module according to the inventors' invention has an advantage that the supercharging pressure can be effectively used because the pressure loss between the supply port and the non-permeation port is extremely lower than that of a general hollow fiber module. In particular, the box pleat module described in Patent Document 6 greatly improves compactness and low-pressure loss by housing two elements in one housing. However, since the structure becomes complicated and the number of sealing points increases, In some cases, the handleability was inferior to the case of storing the element.

JP-A-2-252609 Japanese Patent Publication No. 5-58769 JP 2002-252012 A WO 2004/107490 PCT / JP2005 / 008892 Japanese Patent Application No. 2005-264698 J. et al. Membrane Sci. : 29 (1986) 69-77 Argonne National Laboratory Report: ANL / ESD / TM-144 Mitsubishi Motors Technical Review: 2003 NO. 15 P18

  An object of this invention is to provide the pleat element for gas separation.

The present inventors paid attention to the structure of the pleat element and conducted intensive studies for the purpose of improving the handling property of the pleat module. As a result, instead of installing two box pleat elements facing each other in the housing as in Patent Document 6, a pleat element consisting of two pleated molded bodies and having an appropriate reinforcing frame is installed alone in the housing. As a result, it has been found that handling properties can be improved, and the present invention has been achieved.
That is, the present invention is as follows.
1. Two pleated molded bodies (13) having a gas folding membrane (1) reinforced with a breathable reinforcing material (2) repeatedly folded in the pleated direction on the secondary flow path surface side of the pleated molded body A pleat element characterized in that both end portions are sealed by a sealing means (14), and the two pleated molded bodies are laminated so that each secondary-side channel surface faces outward. . 2. The pleat element according to 1 above, wherein the pleated molded body (13) has a compressibility of 20 kPa or more.

  According to the present invention, it is possible to provide a gas separation module having a low pressure loss and improved handling properties, for example, a nitrogen-enriched air supply device for an internal combustion engine.

[About gas separation module]
In general, a gas separation module is composed of a gas separation membrane, a primary side gas flow path, a secondary side gas flow path, and a housing. The primary side is a mixed gas flow path to be separated, and the secondary side is a mixed gas flow path that permeates the membrane. The primary side is defined as the higher partial pressure when focusing on the gas component that selectively permeates the membrane. In the present invention, the high pressure side is referred to as the primary side, and the low pressure side is referred to as the secondary side. The primary side gas flow path is provided with an intake port, and an exhaust port is provided as necessary. The secondary side gas flow path is provided with an exhaust port, and an intake port is provided as necessary. When the gas mixture to be separated is supplied to the inlet of the primary side gas flow path, the gas mixture spreads to the membrane surface on the primary side, and the gas mixture whose composition has changed according to the selective permeability of the gas separation membrane is secondary. Permeates through the side membrane surface. The mixed gas having a changed composition can be taken out from the secondary side exhaust port and used as it is, or can be used while being continuously diluted with another gas provided from the outside by providing an inlet port on the secondary side. Further, a gas mixture that has not been permeated by providing an exhaust port on the primary side can be taken out and used. The primary side intake port, exhaust port, secondary side intake port, and exhaust port are respectively referred to as “supply port, feed, feed”, “non-permeate port, retentate, retentate”, “scavenging port, purge, purge”. "," Transmission port, permeate, permeate ".

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Gas separation membrane]
In the present invention, the “gas separation membrane” refers to a kind of permselective membrane having the property of preferentially permeating a specific gas from a mixed gas, and a membrane that exhibits selective permeability only under a specific partial pressure of a specific gas. include. The present invention is characterized by using a “flat membrane” that can be pleated as a form of such a gas separation membrane.

  Various materials can be used as the gas separation membrane material. For example, for a nitrogen-rich module, polydimethylsiloxane, polydiphenylsiloxane, polymethylphenylsiloxane, polydimethylsiloxane copolymer, poly-4- Methylpentene-1, polytetrafluoroethylene, polytetrafluoroethylene copolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymer, poly-p-phenylene oxide, polyvinyltrimethylsilane, fluorine Polymerized siloxane / siloxane copolymer, poly [1- (trimethylsilyl) -1-propyne], cellulose acetate, polypropylene, polyethylene, polybutadiene, polyvinyl acetate, polystyrene, and copolymers thereof. Among these, an organopolysiloxane-polyurea-polyurethane block copolymer and a copolymer of perfluoro-2,2-dimethyl-1,3-dioxole and tetrafluoroethylene are preferable. Alternatively, a selectively permeable inorganic material typified by A-type zeolite can be used.

The gas permeability of the gas separation membrane can be expressed by a permeation rate and a separation coefficient. Here, the permeation rate R is represented by the gas permeation amount in unit time, unit area, and unit partial pressure difference, and conventionally, the unit of GPU (Gas permeation unit) = 10 ⁻⁶ cm ³ (STP) / cm ² seccmHg is widely used. in use. Further, the permeation rate per unit film thickness is referred to as a permeation coefficient P, and a unit of barrer = 10 ⁻¹⁰ cm ³ (STP) cm / cm ² seccmHg is widely used conventionally. Although the permeation rate is a physical property of the membrane, the permeation coefficient is a material physical property, and even if the material has an excellent permeation coefficient, if it does not have the necessary and sufficient thin film suitability, it is not suitable for gas separation, so care must be taken . Further, the separation coefficient α is a ratio of the permeation coefficient of an arbitrary gas. The permeation rate and the separation factor are appropriately selected according to the intended application. For example, when used in a nitrogen-enriched air supply device for an internal combustion engine, the following values are preferable. That is,

The oxygen permeation rate R is preferably 100 GPU or more and 1000000 GPU or less, more preferably 200 GPU or more, further preferably 500 GPU or more, still more preferably 1000 GPU or more, particularly preferably 1500 GPU or more, extremely preferably 2000 GPU or more, and most preferably 2500 GPU or more. .
The separation factor α (= RO2 / RN2) of oxygen and nitrogen is preferably 1.1 or more and 1000000 or less, more preferably 1.5 or more, still more preferably 1.8 or more, still more preferably 2.0 or more. .2 or higher is particularly preferable, 2.4 or higher is extremely preferable, and 2.6 or higher is most preferable. If α is smaller than 1.1, a large amount of nitrogen moves from the primary side to the permeate side and is lost accompanying oxygen. Higher α is preferable because the amount of nitrogen accompanying oxygen can be suppressed, but generally, the separation coefficient and the permeation coefficient are in a trade-off relationship.

  The film thickness of the gas separation membrane is preferably 1 μm or more and 1000 μm or less. The lower limit of the film thickness is more preferably 5 μm or more, further preferably 8 μm or more, and most preferably 10 μm or more. The upper limit of the film thickness is more preferably 500 μm or less, further preferably 200 μm or less, still more preferably 100 μm or less, particularly preferably 50 μm or less, and most preferably 20 μm or less. When the film thickness is less than 1 μm, the mechanical strength may be insufficient, and when the film thickness exceeds 1000 μm, the transmission speed may be insufficient.

  In general, the thinner the gas separation membrane, the better because the permeation rate can be improved while maintaining the separation factor. However, in order to avoid damage and the like associated with thinning of the membrane, the gas separation membrane is excellent in gas permeability and mechanical strength. Often formed on top. A gas separation membrane having such a structure is called a composite membrane, a gas separation layer formed on the support membrane is called a separation layer, a skin layer, or an active layer, and a support membrane is sometimes called a support layer. . The composite membrane can be obtained, for example, by applying or impregnating or contacting a gas permeable material to the support membrane. The following description relates to composite membranes.

  As the support layer of the gas separation membrane, various materials can be used as long as they are excellent in gas permeability and mechanical strength and can be pleated, but woven fabrics, nonwoven fabrics, microporous membranes, etc. can be used. . As the microporous membrane, various known microporous membranes such as a polyimide microporous membrane, a PVDF (polyvinylidene fluoride) microporous membrane, and a polyolefin microporous membrane can be used. Among these, a microporous membrane is used as a separator for a lithium ion battery. A polyolefin microporous membrane, particularly a polyethylene microporous membrane is preferred (Japanese Patent No. 3131287).

The porosity of the support layer of the gas separation membrane is preferably 5% or more and 95% or less. The lower limit of the porosity is more preferably 10% or more, further preferably 20% or more, still more preferably 30% or more, and most preferably 40% or more. When the porosity is less than 5%, the gas permeability may be insufficient, and when the porosity exceeds 95%, the mechanical strength may be insufficient.
The average pore diameter of the support layer of the gas separation membrane is preferably 0.1 nm or more and 10 μm or less. The lower limit of the average pore diameter is more preferably 1 nm or more, further preferably 10 nm or more, still more preferably 20 nm or more, particularly preferably 50 nm or more, and most preferably 80 nm or more. The upper limit of the average pore diameter is more preferably 1 μm or less, further preferably 500 nm or less, still more preferably 200 nm or less, and particularly preferably 100 nm or less. When the average pore diameter is less than 0.1 nm, the porosity and the surface aperture ratio are often low, which is not preferable. When the average pore diameter exceeds 10 μm, it is not preferable because it becomes too large with respect to the preferable thickness of the separation layer.

  The thickness of the separation layer of the gas separation membrane is preferably 1 nm or more and 10 μm or less. The lower limit of the film thickness is more preferably 10 nm or more, and further preferably 20 nm or more. The upper limit of the film thickness is more preferably 1 μm or less, further preferably 500 nm or less, still more preferably 300 nm or less, particularly preferably 200 nm, extremely preferably 100 nm or less, and most preferably 50 nm or less. When the transmission coefficient is sufficiently high, the film can be suitably used even when the film thickness exceeds 3 μm. As such an example, a gas separation membrane used for separation of air and water vapor can be raised.

[Breathable reinforcement]
In the present invention, the “breathable reinforcing material” contributes to a means for ensuring gas flow into the pleats by preventing the adhesion of the adjacent gas separation membranes inside the pleats and achieving good membrane utilization efficiency. In addition, it has an auxiliary function for imparting necessary self-supporting properties to the pleated molded body.
The breathable reinforcing material can be provided on both sides or one side of the gas separation membrane, but is preferably provided at least on the low pressure side (secondary side) when the pressure difference between both sides of the gas separation membrane is significant.
As the breathable reinforcing material, a woven fabric, a non-woven fabric, a resin net such as polypropylene, polyester, nylon, or a metal net can be used. Among these, a resin net or a metal net is preferable.

  The thickness of the breathable reinforcing material is preferably 10 μm or more and 5000 μm or less, and the lower limit of the thickness is more preferably 50 μm or more, more preferably 100 μm or more, still more preferably 200 μm or more, particularly preferably 300 μm or more, and more preferably 500 μm or more. Most preferred. The upper limit of the thickness is more preferably 3000 μm or less, further preferably 2000 μm or less, and most preferably 1000 μm or less. If the thickness is less than 10 μm, the mechanical strength may be insufficient. If the thickness exceeds 5000 μm, the gas permeability may be reduced. The thickness of the breathable reinforcing material depends on the degree of compression at the time of measurement. Therefore, measure the degree of compression when the pleat element is configured and the degree of compression when the pleat element is given a total pressure difference during operation. It is preferable.

The porosity of the breathable reinforcing material is preferably 30% or more and 95% or less, and the lower limit of the porosity is more preferably 40% or more, further preferably 50% or more, still more preferably 60% or more, and particularly preferably 70% or more. Preferably, 80% or more is very preferable, and 90% or more is most preferable. If the porosity is less than 30%, the gas separation property may be insufficient, and if the porosity exceeds 95%, the mechanical strength may be insufficient. Since the porosity of the breathable reinforcement depends on the degree of compression at the time of measurement, measure the degree of compression when the pleat element is configured and the degree of compression when the pleat element is given a total pressure difference during operation. It is preferable.
The volume resistivity (Pasec / m ² ) of the breathable reinforcing material to the air flow is preferably 10 ⁶ or less, more preferably 10 ⁵ or less, further preferably 50000 or less, still more preferably 20000 or less, and particularly preferably 10,000 or less. 5000 or less is extremely preferable, and 2000 or less is most preferable.

When an arbitrary porous structure is regarded as an assembly of equivalent circular tubes, the volume resistivity, which is an intrinsic property, can be obtained from the following equation from the equivalent radius of the circular tube of the porous structure and the viscosity of the gas. I can do it.
Volume resistivity = 8 × viscosity / circular equivalent radius ²
Pressure loss = volume resistivity × (length / cross-sectional area) × flow rate For example, a parallel tube circular radius of a sample in which a breathable reinforcing material is laminated alone is 0.1 mm, and a gas viscosity is 1.84 × 10 ^{− At 5} Pasec, the volume resistivity is calculated to be 14700. In an actual pleated element, since the breathable reinforcing material and the gas separation membrane are alternately laminated, the equivalent radius of the circular pipe is slightly smaller and the volume resistivity is slightly larger than when the breathable reinforcing material is laminated alone. When determining the volume resistivity of the breathable reinforcing material from the measurement of flow rate and pressure loss, when using the pleated element made of the breathable reinforcing material for the gas separation module, It is preferable to measure at a gas velocity (linear velocity) corresponding to the flow rate.

The wire diameter when using a net for the breathable reinforcing material is preferably 0.01 mm or more and 2 mm or less. The lower limit of the wire diameter is more preferably 0.02 mm or more, further preferably 0.04 mm or more, still more preferably 0.06 mm or more, and particularly preferably 0.08 mm or more. The upper limit of the wire diameter is more preferably 1 mm or less, still more preferably 0.6 mm or less, still more preferably 0.4 mm or less, and particularly preferably 0.2 mm or less.
As for the mesh at the time of using a net | network for a breathable reinforcement material, 2 or more and 1000 or less are preferable. The lower limit of the number of meshes is more preferably 10 or more, still more preferably 12 or more, still more preferably 14 or more, and particularly preferably 16 or more. The upper limit of the number of meshes is more preferably 100 or less, further preferably 50 or less, still more preferably 30 or less, and particularly preferably 20 or less.

Among the breathable reinforcements, the primary breathable reinforcement reduces the pressure received from the membrane by the high-pressure gas introduced to the primary side, while the secondary breathable reinforcement is introduced to the primary side. The pressure received from the membrane is increased by the high pressure gas being applied. For this reason, it is required that the material for the secondary side breathable reinforcing material be selected more carefully than the primary side breathable reinforcing material. The following relates to the secondary side breathable reinforcement.
The wire diameter when using a net for the breathable reinforcing material is preferably 10 μm or more and 1000 μm or less, and the lower limit of the wire diameter is more preferably 50 μm or more, further preferably 100 μm or more, and even more preferably 150 μm or more. The upper limit of the wire diameter is more preferably 500 μm or less, still more preferably 400 μm or less, and most preferably 300 μm or less. If the wire diameter is smaller than 10 μm, the membrane under pressure may be pushed out from the mesh of the net and may close part or all of the secondary flow path by contacting the membrane with the adjacent membrane. It may not be preferable. When the wire diameter is larger than 1000 μm, the film density is lowered, which may not be preferable.

[Pleated compact]
In the present invention, the “pleated molded body” refers to a structure obtained by pleating a flat membrane gas separation membrane substrate.
In the present invention, the “gas separation membrane substrate” is a basic constituent material of a pleated element composed of a gas separation membrane and a breathable reinforcing material, and if necessary, a laminate of the gas separation membrane and the breathable reinforcing material. I can do it.

  In the present invention, “pleating” refers to processing that gives a flat film a cross-sectional shape such as V-shape, U-shape, Ω-shape by repeating mountain folds and valley folds at a specific pitch. A larger area can be accommodated in the same projected area and the same volume as compared with a flat membrane that does not. Usually, the gas separation membrane and the breathable reinforcing material are laminated and then subjected to pleating. However, it is also possible to insert the breathable reinforcing material between the pleats after performing the pleating with the gas separation membrane alone.

  1 and 2 show schematic views of examples of the pleated molded body of the present invention. In FIG. 1, the cross section of the pleated molded object obtained by pleating the gas separation membrane base material comprised by the gas separation membrane 1 and the air permeable reinforcement 2 is shown. When a long flat membrane having a certain width is pleated, the resulting pleated compact takes a box-like form. In FIG. 2, 4 is an end surface parallel to the pleating direction 6, 4 is an B end surface, 3 is an end surface orthogonal to the pleating direction 6, A is an end surface, the A end surface is combined with the B end surface, 5 is a pleated surface, 6 is Define pleat direction, 7 as pleat length, 8 as pleat height, 9 as pleat width, 10 as pleat pitch

In the present invention, the “length” 7 of the pleat is a length parallel to the pleating direction 6, and an average value can be taken when the length is not constant. The “height” 8 of the pleat is a height from one crest to the other crest of the pleated molded body. If the height is not constant, an average value can be taken. The “width” 9 of the pleat is a length in a direction perpendicular to the pleating direction 6, and can take an average value when the width is not constant. The “pitch” 10 of the pleat is a distance between adjacent peaks of the pleated formed body and the peak of the peaks, and can take an average value when the pitch is not constant.
As a pleating method, a known method can be used. For example, a reciprocating (accordion) pleating machine or a rotary pleating machine can be used.
Since the shape of the pleated body after the pleating process is likely to collapse due to elastic deformation of the gas separation membrane substrate in the released state, it is preferable to hold the shape using an appropriate jig during handling and transportation.

The pleat height 8 is preferably 5 mm or more and 200 mm or less. The lower limit of the height 8 is more preferably 10 mm or more, and further preferably 15 mm or more. The upper limit of the height 8 is more preferably 150 mm or less, still more preferably 100 mm or less, still more preferably 80 mm or less, and particularly preferably 50 mm or less. The height here refers to the inner dimension of the pleated molded body.
The pleat length 7 is preferably 1 mm or more and 300 mm or less, more preferably 250 mm or less, further preferably 200 mm or less, still more preferably 150 mm or less, and particularly preferably 100 mm or less. Even when it is not necessary to reduce the pressure loss, the length is preferably 1000 mm or less, and more preferably 500 mm or less. The length 7 here refers to the inner dimension of the pleated molded body.

[Sealing means]
In the present invention, all the pleats constituting the pleated molded body are characterized in that both ends of the secondary flow path are sealed with sealing means. In the present invention, such a structure is called an envelope structure.
FIG. 3 shows an explanatory view of an example of the sealing means of the present invention. The pleated molded body 11 is once opened to be flat so that the secondary flow path is on top, and a sealing material 12 such as hot melt resin or adhesive is applied along both ends of the flat surface, and then repeated again. By folding, both ends of the secondary flow path of the pleated molded body can be suitably sealed. Here, 13 is a pleated molded body after sealing, 14 is a sealing portion, 15 is an overall view of the pleated molded body after sealing, and 16 is a pleated opening of the pleated molded body after sealing. By applying the sealing means, each rectangular pleat forms an envelope structure in which three sides are closed and one side is opened. At this time, the envelope structure is opened toward the secondary pleat surface. When such a structure is adopted, the high-pressure gas on the primary side flows in the direction of 18 with respect to one envelope structure indicated by 17, and the low-pressure gas on the secondary side after passing through the membrane is in the direction of 19 Flowing.

[Pleated element]
In the present invention, the “pleat element” is a central member constituting the pleat module, and includes two pleated molded bodies and a reinforcing frame. In other words, the pleat element can be said to be a pleat module (gas separation module) before having appropriate intake ports, exhaust ports, and flow paths.
FIG. 4 shows a schematic diagram of an example of a pleated element of the present invention. FIG. 4a shows an example in which two pleated molded bodies 13 are arranged so that the primary pleat surfaces face each other. Here, reference numeral 20 denotes a reinforcing plate, which can be bonded to the B end surface 4 of the pleated molded body. By providing a reinforcing plate, the gas separation membrane exposed on the B end face 4 is protected, and by applying force to both reinforcing plates 20 in the width direction of the pleats, the pleated molded body is evenly compressed as necessary. can do.

  In the present invention, the surface on which the two pleated compacts face each other is the primary side, that is, the high pressure side. Therefore, if there is a space 21 as shown in FIG. 4b, the space 21 does not sufficiently contact the gas separation membrane. This is not preferable because the high-pressure side gas passing through the passage increases. When it is difficult for the primary pleat surfaces facing each other to come into contact with each other for some reason, the high-pressure side gas passing without sufficiently contacting the gas separation membrane is reduced by using the filler 22 as shown in FIG. 4c. can do. As such a filler, for example, a sponge or the like can be preferably used.

The term “in contact with” here means a state in which the primary pleat surfaces of the opposed pleated molded bodies are arranged with a gap such that the high-pressure gas passing without sufficiently contacting the gas separation membrane can be ignored. It is not always necessary that the primary pleat surfaces of the opposed pleated molded bodies are in close contact or bonded. As a measure of the gap, it is preferably 10 times or less of the pleat pitch 10 of the pleated molded body, more preferably 5 times or less, further preferably 3 times or less, still more preferably 2 times or less, particularly preferably 1 time or less, 0 .5 times or less is extremely preferable, and 0.2 times or less is most preferable.
FIG. 4d shows a case where the gas separation membrane is not divided for each pleated molded body and continues through two pleated molded bodies, and the present invention includes such a case.

[Reinforcement frame]
In the present invention, the “reinforcing frame” refers to a structural material for hermetically separating the primary side flow path and the secondary side flow path of the pleat element by airtight connection with a housing or the like. The reinforcing frame is provided at least in the vicinity of the A end surface 3 on the secondary pleated surface of the pleated molded body, and is in close contact with the sealing means on the secondary pleated surface.
FIG. 5 shows a schematic view of an example of a pleated element comprising a reinforcing frame 23 according to the invention. For example, after arranging the two pleated molded bodies 13 so that the primary pleated surfaces face each other and come into contact with each other, the respective B end surfaces 4 are bonded to the reinforcing plate 20, and the pleated molded bodies are attached to the pleats as necessary. By compressing in the width direction and then setting it in a predetermined mold and performing injection molding, the entire circumference (near the A end surface 3 of one pleat molded body, secondary side pleat surface of the one pleated body → the vicinity of the A end surface 3 of one reinforcing plate → the other A pleat element 24 is formed by forming a reinforcing frame 23 across the secondary pleat surface in the vicinity of the A end surface 3 of the pleated molded body in the vicinity of the A end surface 3 of the other reinforcing plate. Various materials can be used for the reinforcing frame such as resin and metal as long as the object of the present invention is achieved. However, when the reinforcing frame is used as a sealing agent as it is, a soft resin or a foamed resin is preferably used. I can do it. Further, in order to facilitate the close contact with the housing, the reinforcing frame can be additionally provided with close contact means such as a collar and an O-ring groove as required.

[Pleated element shape and properties]
The width 9 of the pleat is preferably 10 mm or more and 1000 mm or less, more preferably 800 mm or less, further preferably 500 mm or less, still more preferably 400 mm or less, and particularly preferably 300 mm or less. The width here refers to the inner dimension of the pleated molded body.
The pitch 10 of the pleats is preferably 0.1 mm or greater and 10 mm or less. The lower limit of the pitch is more preferably 0.4 mm or more, further preferably 0.6 mm or more, still more preferably 0.8 mm or more, and particularly preferably 1.0 mm or more. The upper limit of the pitch is more preferably 8 mm or less, still more preferably 6 mm or less, and still more preferably 4 mm or less. The pitch can be adjusted by the inner width of the reinforcing frame and the number of pleats to be stored.

  The degree of compression of the pleated molded body means a pressure (kPa) when the B end surfaces 4 of the pleated molded bodies facing each other are compressed toward the inside of the pleated molded body. The degree of compression of the pleated molded body is preferably equal to or higher than the differential pressure when the gas separation module is operated. Specifically, the compression degree of the pleated molded body is preferably 20 kPa or more, more preferably 50 kPa or more, still more preferably 100 kPa or more, still more preferably 150 kPa or more, particularly preferably 200 kPa or more, extremely preferably 250 kPa or more, and 300 kPa or more. Is most preferred. If the degree of compression is 400 kPa or more, depending on the material of the gas separation membrane, the net used as a breathable reinforcing material may be compressed and may be destroyed or damaged. Therefore, it is preferable to select a material in consideration of this. .

[housing]
In the present invention, the “housing” provides an air inlet, an air outlet, and a flow path suitable for the pleat element to constitute a pleat module (gas separation module), and functions other than the gas separation function (protection from mechanical destruction) Function, connection function with external piping, etc.).
FIG. 6 shows a schematic view of an example of the housing of the present invention. For example, the pleated element 24 as illustrated in FIG. 5 is press-fitted into a compartment 42 in the housing body 41. Here, the housing body 41 includes a slit-like exhaust port 43 for gas discharged from the secondary side flow path of the pleat element 24. Next, two openings of the compartment 42 are sealed with the two plates 44, respectively, and a gas separation module is configured. The plate 44 includes an intake / exhaust pipe 46 for the primary flow path, and is connected to the primary flow path of the pleat element inside the housing via the flow path 45.

[Nitrogen enrichment module]
The “gas separation device” in the present invention is composed of auxiliary equipment such as a pipe for connecting a gas separation module and an external circuit, a sensor, and a control device. Hereinafter, as an example, the performance when the gas separation module of the present invention is used as a nitrogen-enriched air supply device (nitrogen-enriched module) for an internal combustion engine will be described.
The nitrogen enrichment module can be operated in various combinations such as primary side pressurization, secondary side atmospheric pressure, primary side atmospheric pressure, secondary side decompression, etc. Since many diesel engines are equipped with a turbocharger, they can be suitably operated with a combination of primary pressure and secondary atmospheric pressure.

FIG. 7 is a configuration diagram of a nitrogen-enriched air supply device for an internal combustion engine showing an example of an embodiment of the present invention. First, the compressed air compressed by the turbocharger 38 is supplied to the inlet 29 of the primary side flow path of the nitrogen enriching module 28, and is guided by the flow path control means 30 to the base material section flow path inside the pleat element. Air is taken out as nitrogen-enriched air from the outlet 32 of the primary channel while permeating and removing oxygen and nitrogen at a constant rate through the gas separation membrane 31 having oxygen selective permeability inside the pleat element. . The nitrogen-enriched air is guided to the engine inlet 35 and is combusted by the engine 36 and then discharged as exhaust gas from the engine outlet 37 to drive the turbocharger 38. The oxygen-enriched air that has permeated to the secondary side may be led from the opening 33 to the vehicle compartment, engine, catalyst, and the like through a pipe or the like, but it is preferable that the oxygen-enriched air is directly discharged from the opening 33 to the outside. That is, if the oxygen-enriched air stays on the secondary side, the oxygen partial pressure difference decreases and the function of the gas separation module decreases. Therefore, the gas 34 (with a partial pressure of oxygen lower than the primary side on the secondary pleat surface) It is preferable to remove the permeated oxygen-enriched air from the pleated surface by flowing non-compressed air or the like from the outside. In the present invention, such an operation is called scavenging.

For example, when oxygen enriched air with an oxygen concentration of 19% passes through the secondary side at a flow rate of 0.2 m ³ / min when taking out 2 m ³ / min of nitrogen enriched air with an oxygen concentration of 19% from the primary side, at least It is preferable to flow 10 times (2 m ³ / min) of the scavenging air to the secondary membrane surface. Since an automobile traveling at a speed of 60 km / h receives air at a wind speed of 1000 m / min from the front, a preferable amount of scavenging air can be flowed from the outside onto the pleat surface by providing a wind receiving area of 200 cm ² .

The pressure on the primary side is preferably from atmospheric pressure to 10,000 kPaG, more preferably 10 kPaG or more, still more preferably 100 kPaG or more, even more preferably 150 kPaG or more, particularly preferably 200 kPaG or more, extremely preferably 300 kPaG or more, most preferably 400 kPaG or more. preferable.
The flow rate of the nitrogen-enriched air required for the nitrogen-enriched module can be obtained from the displacement of the diesel engine and the target rotational speed. For example, the flow rate required for a 2L diesel engine to operate at 2000 revolutions / minute can be calculated as 2L × 2000 revolutions / minute ÷ 2 = 2 m ³ / minute.

When considering the performance of the gas separation device, it is convenient to use the device permeation rate (GPUm ² ) defined by the product of the permeation rate (GPU) of the gas separation membrane and the membrane area (m ² ). For example, when nitrogen enriched air having an oxygen concentration of 19.0% is to be taken out at a flow rate of 4 Nm ³ / min, the average oxygen concentration on the primary side is 19.0%, the average pressure is 100 kPaG, and the secondary side (with scavenging air) Assuming an average oxygen concentration of 20.9%, an average pressure of 0 kPaG, and a separation factor of 2.0, the required apparatus permeation rate is 25992 GPUm ² for oxygen. When the permeation rate of oxygen through the gas separation membrane is 1000 GPU, the required membrane area is 26.0 m ² , and when the pleat pitch is 2 mm (corresponding to an average intermembrane distance of 1 mm), the inner volume of the pleat element is the Runge-Kutta integral. 26.0 L is obtained from the used cross flow model calculation.

The pressure loss on the primary side is preferably 0 kPa or more and 50 kPa or less, more preferably 10 kPa or less, further preferably 5 kPa or less, still more preferably 1 kPa or less, particularly preferably 0.5 kPa or less, and most preferably 0.2 kPa or less. . When the pressure loss exceeds 50 kPa, the generated torque of the diesel engine is reduced due to the loss of the pressure corresponding to the turbocharger supercharging pressure, and at the same time, 1 as the primary total pressure in the latter half of the gas separator decreases. The oxygen partial pressure on the secondary side decreases, and the performance of the gas separation device decreases.
Nitrogen enrichment as described above is an example of typical gas separation, and other gas separation (for example, hydrogen recovery from a mixed gas, steam recovery, etc.) can be performed in the same manner.

  The gas separation module according to the present invention is used as a gas separation module having excellent ventilation resistance for various uses such as air conditioners and industrial gas production devices in addition to air separation used in nitrogen-enriched air supply devices for internal combustion engines. it can.

Schematic of an example of the pleated molded body of the present invention Another schematic view of an example of the pleated molded body of the present invention Explanatory drawing of the sealing means of this invention Schematic of an example of a pleated element of the present invention Schematic of an example of a pleated element with a reinforcing frame of the invention Schematic of an example housing of the present invention The block diagram of the nitrogen enriched air supply apparatus for internal combustion engines which shows the example of embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas separation membrane 2 Breathable reinforcing material 3 A end surface 4 B end surface 5 Pleated surface 6 Pleated direction 7 Pleated length 8 Pleated height 9 Pleated width 10 Pleated pitch 11 Pleated molded body 12 before sealing Material 13 Sealed Pleated Molded Body 14 Sealed Portion 15 Whole Pleated Molded Body After Sealing FIG. 16 Pleated Opened Portion of Sealed Pleated Molded Body 17 One Pleat Envelope Structure 18 Primary Side High Pressure Gas Low pressure gas flow 20 on the secondary side 20 Reinforcement plate 21 Space 22 Filler 23 Reinforcement frame 24 Pleated element 28 Nitrogen-rich module 29 Primary side inlet 30 Flow path control means 31 Gas separation membrane 32 Primary side outlet 33 Opening 34 Gas for scavenging 35 Engine inlet 36 Engine 37 Engine outlet 38 Turbocharger 41 Housing body 42 Compartment 43 Exhaust ports 44 plate 45 passage 46 follows side passage feeding exhaust pipe

Claims (2)

  The two pleat molded bodies (13) having a gas folding membrane (1) reinforced with a breathable reinforcing material (2) repeatedly folded, and both ends of the pleated molded body in the pleat direction on the secondary channel surface side Is sealed by the sealing means (14), and the two pleated molded bodies are laminated so that the respective secondary side flow passage faces outward. The pleat element according to claim 1, wherein the pleated body (13) has a compressibility of 20 kPa or more.

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