JPH047252B2 - - Google Patents

Description

[Detailed description of the invention]

<Field of Application> The present invention relates to membrane separation technology. More particularly, the present invention provides a fluid separation device containing a fluid separation element that can be used to separate a fluid enriched in a particular component from a fluid mixture. In particular, an oxygen enrichment device housing an oxygen enrichment element suitable for obtaining oxygen-enriched air with increased oxygen concentration from the atmosphere is provided. <Prior Art> In recent years, membrane separation technology has made remarkable progress in the fields of reverse osmosis, ultrafiltration, dialysis, etc., and membrane modules of hollow fiber type, flat plate type, spiral type, etc. are used depending on the purpose. The present invention is an improvement of a fluid separation element constituting a flat membrane module and a fluid separation device using the same. In general, a flat plate module has a so-called fluid separation element, which consists of a support plate with a spacer for passing the permeated fluid and a fluid separation membrane layered on top of the spacer, stacked in multiple layers with a spacer for passing the raw material fluid interposed therebetween. things are used. Here, it is very important to completely seal the support plate and the fluid separation membrane so as not to reduce the separation efficiency. A method of adhesive sealing was used. However, the method using packing for sealing has the disadvantage that the seal is likely to be incomplete, and the method of adhesive sealing using adhesive has the disadvantage that it adheres with the inserted spacer for passage of permeate fluid, so it is difficult to adhere to the back side of the membrane. It is difficult and the width of the adhesive tends to spread unevenly, and if it is too narrow, a sealing failure will occur, and if it is too wide, the effective membrane area will be reduced.Therefore, there has been a strong desire for improvement. <Object of the Invention> The object of the present invention is to improve the drawbacks of the conventional fluid separation device using the flat module. More specifically, to ensure the adhesive seal between the support plate and the separation membrane in the fluid separation element, to reduce the amount of adhesive used, and to make the width of the adhesive layer relatively uniform and narrow. The purpose is to improve the following. <Structure of the Invention> As a result of intensive research to achieve the above object, the present inventors have discovered that, instead of arranging a spacer for passing the permeated fluid over the entire surface of the adhesive layer as in the conventional method, the spacer is placed inside the adhesive zone. It has been found that it is effective to adhesively seal the end of the spacer with the end inserted into the spacer, and has arrived at the present invention. That is, the present invention provides a permselective membrane capable of selectively permeating a specific component from a fluid mixture, a support plate, a spacer for passing a permeate located between the permselective membrane and the support plate, and a permeate outlet for a large number of fluids. A module in which separation elements are arranged in a stacked manner through a source fluid passage spacer made of a compressible member, means for supplying a fluid mixture onto the selectively permeable membrane surface, and a means for supplying a fluid mixture onto the selectively permeable membrane surface; In a fluid separation device having a means for lowering the pressure to a value lower than the pressure, and a means for taking out the fluid that has passed through the selectively permeable membrane from the inner space of the element,
Most of the end of the spacer for passing the permeate fluid is located within a region substantially 1/4 from the inner end of the adhesive zone that is adhesively sealed around the selectively permeable membrane of the fluid separation element to the support plate using an adhesive. are arranged and bonded together, and the spacer for passage of raw material fluid is made of a soft compressible member selected from the group of soft rubber, soft foam, and soft sponge, This is what we provide. The present invention will be explained in more detail below with reference to the drawings. First, the fluid separation element of the present invention has a structure in which a permeated fluid passes through a support plate 2, as shown in FIG. 1 (plan view of the element) and FIG. spacer (hereinafter also referred to as inner spacer because it is located inside the element) 5 is stacked, and the selectively permeable membrane 1 is stacked on top of it, and its surroundings are adhesively sealed with adhesive. It is characterized in that the distribution state of the adhesive and the end 7 of the inner spacer have a specific positional relationship. That is, the end and most of the inner spacer in the element is located inside the band-like region 6 where the adhesive is present, and more preferably substantially in the inner half region of the band-like region of the adhesive. Particularly preferably, it is located substantially in a 1/4 area from the inner end of the band-shaped area of the adhesive. Here, "substantially" means that most of the outer circumferential end 7 of the inner spacer is located within the region specified as above. Note that it is practically preferable that the outer circumferential end 7 of the inner spacer is not located inside the inner end of the bonded portion, since this prevents the membrane from sinking. Further, in the fluid separation element of the present invention, as exemplified by the permeated fluid outlet 3 in FIG. A permeate outlet is provided which communicates with the external space for removal from the space. Further, as illustrated in FIGS. 1 and 2, a preferred embodiment of the fluid separation element of the present invention is such that when the fluid separation element is laminated in multiple layers to form a fluid separation module, it is necessary to allow the raw material fluid to pass through the membrane surface. A compressible member is attached to a part of the permselective membrane surface at the adhesive part as a raw material fluid passage spacer (hereinafter also referred to as an outer spacer because it is located outside the element) 4. If the thickness of the adhesive layer at the bonding part is uniform, an external spacer made of a non-compressible material can be used, but if an external spacer made of a compressible material is used, if the thickness of the adhesive layer is uniform, Needless to say, even in the case of non-uniform thickness, there is an advantage that it is easy to obtain a stable module in which the elements are laminated in multiple layers.
Examples of such compressible members include soft natural rubber, silicone rubber, soft styrene-butadiene rubber, soft rubber such as chloroprene rubber, foam rubber, urethane foam, vinyl foam,
Soft foams such as polystyrene foam and polyethylene foam, soft sponges such as phenol resin sponges and urea resin sponges, and cork,
Examples include felt. Among them, those preferably used as the compressible member of the present invention include chloroprene rubber, chloroprene rubber foam, polystyrene foam, and polyethylene foam. Note that when attaching the outer spacer to the membrane surface, any form of attachment may be used; for example, double-sided tape or silicone-based adhesive (first
An example is a method using 4-a) in the figure. Further, in a preferred embodiment of the fluid separation element of the present invention, the thickness of the layer made only of the adhesive material in the portion of the adhesive portion 6 where the inner spacer 2 is not present is as follows:
It is preferably in the range of 0.5 to 1.5 times the thickness of the inner spacer, particularly preferably substantially equal to the thickness of the inner spacer. By satisfying these conditions, the change in thickness at the inner end of the adhesive part and the outer circumferential end of the spacer is small, and the permselective membrane layered on the inner spacer is able to maintain the thickness of the spacer during use. When pressed against a surface, unevenness is unlikely to occur on the membrane surface, and it is possible to operate stably over a long period of time while maintaining the membrane performance. The selectively permeable membrane 1 used in the fluid separation element of the present invention may be any membrane as long as it can selectively permeate a specific component from a mixture of liquids and gases. Its specific shape consists of only a flat membrane with selective permeation performance,
Examples include those in which a flat membrane having the selective permeability is molded on another sheet-like porous substrate. For example, in the case of an oxygen selectively permeable membrane that selectively permeates oxygen from the air, a polyolefin-based membrane such as poly4-methylpentene-1 or a copolymer of it with other polyolefins, vinylsilane, allylsilane, etc. Polysulfone porous material 1 in which membrane 1-a is molded onto non-woven fabric or woven fabric 1-c.
-c or a laminated film laminated on a porous polypropylene flat film. The support plate of the present invention maintains the form of the element,
It has the function of separating the internal space from the external space in an air-tight or liquid-tight manner. The element of the present invention may have a structure in which an internal spacer and a permselective membrane are laminated and adhesively molded on both sides of a support plate, in which case the function of the support plate is mainly to maintain the shape of the element. becomes. In the case of a support plate in which an internal spacer and a membrane are laminated and adhesively molded on one side, examples of the support include aluminum plates, duralumin plates, metal plates such as iron plates, polypropylene plates, hard PVC plates, and FR-PET plates. , a plastic plate such as an unsaturated polyester plate, etc., and the surface thereof may be flat or uneven. Specific examples of supports that are laminated and adhesively molded on both sides of a support plate include those in which at least a portion of the inside of the support plate is hollowed out to the extent that the shape of the element can be maintained, stainless steel wire mesh, and polypropylene porous. Examples include boards. Furthermore, the inner spacer of the present invention is not particularly limited as long as it is a sheet-like member in which a space through which a permeating fluid can flow is formed, and a net-like member is a preferable example thereof. Such a net material preferably has a rough, uneven shape, and may be made of either plastic or metal, but plastic is preferred from the viewpoint of weight reduction. If it is made of plastic, it is preferably stiff, and examples of the material include polypropylene, polyethylene terephthalate, and nylon. An example of a commercially available net material is DuPont.
Examples include Vexar (trade name) manufactured by Co., Ltd. and Netron (trade name) manufactured by Tokyo Polymer Co., Ltd. The thickness of this inner spacer is 0.3
-3 mm is preferable, and 0.5 - 2 mm is more practically desirable. Furthermore, in the fluid separation element of the present invention, when the surface of the inner spacer has large irregularities and pressure is applied from the outside to the selectively permeable membrane surface during fluid separation, the membrane is prevented from deforming into a shape corresponding to the irregularities and being damaged. In order to achieve this, it is preferable to further insert a sheet-like porous material between the spacer and the membrane as necessary. Specific examples of such sheet-like porous materials include nonwoven fabrics made of polyethylene terephthalate, polypropylene, nylon, etc., and porous membranes made of polypropylene, cellulose ester, polytetrafluoroethylene, polycarbonate, recycled cellulose, etc. The element in the present invention is provided with an outlet for taking out the concentrated fluid obtained by passing through the permeable membrane on one or both sides. It is necessary to select an outlet with a cross-sectional area and length that causes almost no pressure loss at that part.Especially when using both sides of the support plate, the outlet that is shared by both sides should be The number of outlets can be halved compared to the case where each outlet is provided separately.
Furthermore, the number of collecting pipes that collect the concentrated fluid from the outlet can be reduced, and the structure of the elements and modules can be simplified.
The outer periphery of the element, except for the outlet, is sealed to prevent fluid leakage. That is, the structure is such that mixing of the feed fluid mixing section and the concentrated fluid that has passed through the membrane does not occur. As the adhesive used in the adhesive portion of the element of the present invention, any adhesive may be used as long as it can adhesively seal the back surface of the support plate and the selectively permeable membrane. When selecting such an adhesive, consider the operability when preparing the adhesive, the operability and adhesion when applying the prepared adhesive, adhering and solidifying each member, and sealing, and the resulting element. The durability of the adhesive is important when using a fluid separation device containing a fluid separator. Particularly when the permselective membrane is laminated on a porous membrane as described above,
It is necessary to select an adhesive that can easily penetrate into the porous membrane to ensure adhesive sealing. Furthermore, in order to improve the adhesion retention on the support plate surface, it is also effective to use a support plate with minute irregularities formed on the support plate surface. The fluid separation device of the present invention is characterized by using a module in which a large number of the above-mentioned fluid separation elements are stacked together with an outer spacer interposed therebetween. means for discharging the fluid mixture;
It has means for maintaining the internal pressure of the element lower than the external pressure, and conduit means for removing the fluid that has permeated through the membrane from the interior of the element through a fluid outlet and collecting it for use. For example, in the case of a membrane-type oxygen enrichment device for separating oxygen-enriched air from air in a gas separation device, a flow path through which the atmosphere can flow is provided on the membrane surface, as illustrated in Fig. 3. The module has a module in which a large number of elements are stacked and arranged with an external spacer 4 sandwiched between the elements 20, and the module takes in atmospheric air C from the outside and supplies the atmospheric air to the external space of the elements in the module to supply the atmospheric air to the membrane surface. A blowing means 18 for discharging the spent atmosphere D with a reduced oxygen concentration to the outside of the device; Vacuum pump means 1 for taking out from inside the element
0, and conduit means for collecting oxygen-enriched air from within each element and communicating it to an outlet for oxygen-enriched air A in the device. The oxygen enrichment device also includes a cooling means 12 for cooling the oxygen-enriched air when water is also concentrated during membrane permeation, a means 13 for separating water droplets generated in the oxygen-enriched air by the cooling, A decompression means 14 such as an orifice for making the cooling means function more effectively, a water retention means 11 that retains and vaporizes the water from the water separation means 13 on the surface of the cooling means through a conduit 17, and oxygen-enriched air for use. Preferably, means 15 for adjusting the flow rate of A and flow rate measuring means 16 are provided. Note that B indicates surplus oxygen-enriched air. In such an oxygen enrichment device, in order to minimize concentration polarization at the membrane surface of each element that makes up the module and maintain separation efficiency close to the original membrane performance, the flow rate of atmospheric air sent to each membrane surface is oxygen enriched. At least 5 times the amount of air, preferably at least 10 times,
More preferably, it is 30 times or more. That is, it is necessary to have a significant amount of air flowing through each passage between the elements in the module as uniformly as possible. Therefore, it is desirable that the spacing between each element formed by the outer spacer 4 provided between the elements be as uniform as possible. In the present invention, by using a compressible outer spacer in addition to the above-mentioned improved adhesive seal form, the module is assembled while maintaining appropriate uniformity of the spacing between each element. It has become extremely easy to do so. For convenience, FIG. 3 shows a case where the outer spacer 4 is located in a direction perpendicular to the flow of oxygen-enriched air inside the element 20, but the flow of oxygen-enriched air as shown in FIG. It is preferable to arrange the external spacer 4 in parallel with the oxygen-enriched air because it allows the atmosphere to flow countercurrently with the flow of oxygen-enriched air and improves the separation efficiency. The fluid separation element and fluid separation device of the present invention are advantageously used for oxygen enrichment as described above, but can also be used to enrich helium gas, hydrogen gas, etc. by appropriately selecting the performance of the selectively permeable membrane. It can also be used to concentrate and separate gases, and to separate liquid mixtures such as reverse osmosis, ultrafiltration, and pervaporation. A more detailed explanation will be given below with reference to examples.
However, the present invention is not limited to this example in any way. Examples 1 and 2 Comparative Examples 1 and 2 As shown in Fig. 2, aluminum plate 2 (thickness 1 mm, 250 mm
x 500 mm), set the polypropylene net 5 (thickness 0.5 mm, 14 meshes) cut to the dimensions listed in Table 1 on top, and apply epoxy adhesive 6 so that the positional relationship shown in Table 1 is achieved. Width approx. 10mm, thickness approx.
After applying a strip of 0.5mm, separate polyethylene terephthalate nonwoven fabric 1-c (thickness 230μ, basis weight
Polysulfone porous membrane 1 formed on 180g/m ² )
-b as a base material and a polar film 1-a of poly-4-methylpentene-1 on the surface (with oxygen selective permeability)
The provided oxygen selectively permeable membrane 1 was pasted onto the adhesive coated area and pressed while allowing the adhesive to permeate to the back surface of the poly-4-methylpentene-1 polar membrane to solidify the adhesive to obtain an oxygen-enriching element. The adhesive solidification was performed with a thin tube-shaped enriched air outlet inserted at one location in the adhesive zone of each element. Table 1 shows the results of examining the state of each element thus obtained after adhesion. That is, when the methods of Examples 1 and 2 were carried out, the adhesion between the permeable membrane and the adhesive was good, there was no leakage of gas between the boundary layers, and the permeable membrane in the overlapping part of the inner spacer end and the adhesive zone was The surface was smooth and good with no unevenness. In Comparative Example 1, the width of the adhesive taken up by the inner spacer (net) expanded, and there were some areas where the adhesive was not sufficiently adhered to the permeable membrane, making it impossible to obtain a stable adhesive state.
In Comparative Example 2, the adhesive condition was good, but because a groove was inevitably formed between the inner spacer end and the adhesive zone, the permeable membrane surface was depressed and the permeable membrane was damaged during gas suction action (gas permeation). This caused a gas leak. Furthermore, since there is no effect of fixing the inner spacer with an adhesive, the inner spacer may be displaced, resulting in a large dent in the film surface. As mentioned above, Examples 1 and 2 were the optimal methods.

[Table] Example 3 On the membrane surface of the adhesive zone on two opposite sides along the longitudinal direction of the element obtained in Example 1, compressible chloroprene foam was added as an outer spacer (width 10 mm, thickness 5 mm). ) was adhered with a silicone adhesive, and an oxygen enrichment module was prepared by stacking 30 sheets of the same, and an oxygen enrichment device as shown in FIG. 3 was assembled. Air flow within the module in this device was good, and the adhesive seals in each element were maintained for a long period of time, with no damage to the membrane surface. <Effects of the Invention> The fluid separation device using the fluid separation element of the present invention can ensure a more reliable seal by adopting a specific adhesive seal form, and in particular, the width of the adhesive band can be made relatively uniform. It has the advantage that it is easy to make the membrane narrow and the amount of adhesive used can be reduced, and the effective membrane area can be made as large as possible. In addition, when combined with a compressible outer spacer, there is an advantage that when a module is formed by laminating a large number of elements, it can be easily assembled while keeping the spacing between each element relatively uniform. Furthermore, in the present invention, there is little damage to the membrane surface near the adhesive seal portion, and long-term durability can be maintained.

[Brief explanation of drawings]

FIG. 1 schematically shows a plan view of a fluid separation element according to the present invention, and FIG. 2 is a cross-sectional view of the vicinity of the end (adhesive portion) of the element in the α-α′ plane in FIG. This is shown in the figure. Further, FIG. 3 shows an oxygen enrichment device as an embodiment of a fluid separation device using the fluid separation element of the present invention.

Claims (1)

[Claims] 1 Compressing a large number of fluid separation elements each including a permselective membrane capable of selectively permeating a specific component from a fluid mixture, a support plate, a spacer for passing the permeate located between the permselective membrane and the support plate, and a permeate outlet. modules arranged in a layered manner through spacers for passage of raw material fluid made of a flexible material; means for supplying a fluid mixture onto the selectively permeable membrane surface; and a means for taking out the fluid that has passed through the selectively permeable membrane from the inner space of the element, wherein the periphery of the selectively permeable membrane of the fluid separation element is adhesively sealed to the support plate with an adhesive. Most of the ends of the spacer for passing the permeate fluid are arranged and bonded together within a region substantially 1/4 from the inner end of the adhesive zone, and the spacer for passing the raw material fluid is made of soft rubber, soft foam, or A fluid separation device comprising a soft compressible member selected from the group of soft sponges.