JP3956262B2 - Liquid separation membrane module - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a liquid separation membrane module used in a reverse osmosis membrane separation device.
[0002]
[Prior art]
The separation membrane is formed in a bag shape, and has a permeated water flow path material inside. The raw water flow path material is superimposed on a three-layer structure whose one end communicates with the water collection pipe, and is wound around the water collection pipe. Spiral separation membrane elements have been proposed.
[0003]
In the above spiral separation membrane element, when the three-layer structure in which the raw water channel material is superimposed on the separation membrane provided with the permeate channel material is wound around the water collecting pipe, both ends of the three-layer structure are bonded to the adhesive. It is glued with.
[0004]
The raw water is passed through the outside of the bag-like separation membrane, and the permeated water that has permeated the inside of the bag-like separation membrane passes through the permeate flow path material and flows into the water collecting pipe where the inside of the separation membrane is communicated. , Extracted outside the membrane element. In general, the permeated water channel material is a single tricot knitted fabric having a groove on one side, reinforced with an epoxy resin, melted and fixed (Japanese Patent Laid-Open No. 60-19001), or a double tricot knitted fabric having a groove on both sides. Those reinforced with resin are mainly used. This permeate flow path material supports the reverse osmosis membrane and plays a role of guiding permeate into the water collecting pipe by the grooves of the permeate flow path material.
[0005]
[Problems to be solved by the invention]
Usually, in order to membrane-separate a solution using a liquid separation membrane module using a reverse osmosis membrane, it is necessary to apply a pressure higher than the osmotic pressure of the target solution. At that time, a differential pressure of about 0.5 to 1 MPa is applied to the supply liquid side and the permeate side. At this time, if the permeate channel material is the single tricot 31 shown in FIG. 7 or the double tricot knitted fabric 32 shown in FIG. 8, the reverse osmosis membrane sinks into the mutually parallel grooves on one side or both sides, and the thin film is blocked. Therefore, there arises a problem that the flow path resistance increases. When the operation is continued for a long time while the reverse osmosis membranes are depressed in the mutually parallel grooves of the permeate flow channel member under high pressure, the reverse osmosis membrane is in contact with the uneven surface of the single tricot 31 as shown in FIG. 33 is deformed, and the cavity through which the permeated water passes is crushed and sufficient performance cannot be obtained. When the double tricot knitted fabric 32 is used, as shown in FIG. 10, the reverse osmosis membranes 33 and 34 are deformed, and the cavities through which the permeated water passes are crushed so that sufficient performance cannot be obtained. It was.
[0006]
The present invention was made to solve the above-described problems of the prior art, and suppresses an increase in flow resistance and deformation of the reverse osmosis membrane due to the depression of the reverse osmosis membrane into the permeate flow channel material, An object is to provide a practical liquid separation membrane module capable of maintaining reverse osmosis membrane performance.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the liquid separation membrane module of the present invention is a liquid separation membrane module in which a flow path material that supports the back side of a reverse osmosis membrane that receives a stock solution is incorporated.
The flow path material is formed by laminating a fabric A having a concavo-convex structure in a cross section and a flat fabric B on the concavo-convex surface of the fabric A,
The fibers constituting the fabrics A and B are core-sheath type composite (conjugate) fibers having a low melting point polymer as a sheath and a high melting point polymer as a core, and the fabrics A and B are fused together by heating. Is stiffened by
The fabrics A and B are integrated by fusion ,
The space formed by the concave portion of the fabric A and the flat fabric B forms a flow channel that does not sink due to the pressure required for reverse osmosis.
[0008]
Two layers are preferable when the fabric B is laminated on one side of the fabric A, or three layers when the fabric B is laminated on both sides of the fabric A.
[0009]
In the liquid separation membrane module, it is preferable that the fabric A is a tricot knitted fabric having an uneven structure, and the fabric B is a woven fabric or a non-woven fabric.
[0010]
In the liquid separation membrane module, it is preferable that the fabric A is a single tricot knitted fabric, and the fabric B laminated on one uneven surface of the knitted fabric is a woven fabric or a non-woven fabric.
[0011]
In the liquid separation membrane module, it is preferable that the fabric A is a double tricot knitted fabric, and the fabric B laminated on the uneven surfaces on both sides of the knitted fabric is a woven fabric or a non-woven fabric.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the fabric A may be any fabric such as a woven fabric, a knitted fabric, a nonwoven fabric, a lace fabric, a net, and a braid as long as the cross section is an uneven structure. Among these, a single tricot knitted fabric, a double tricot knitted fabric and the like are preferable because they are excellent in dimensional stability.
[0015]
Next, the type of fabric B, knitted fabric, nonwoven fabric, etc. is not limited as long as the fabric B is flat. Among these, a woven fabric or a nonwoven fabric is preferable. Examples of the woven fabric include plain weave, oblique woven fabric, and satin weave, and examples of the nonwoven fabric include carded nonwoven fabric, airlaid nonwoven fabric, wet nonwoven fabric (including synthetic fiber paper), spunbond nonwoven fabric, and flash nonwoven fabric. , Melt blown nonwoven fabric, chemical bonding nonwoven fabric, thermal bond nonwoven fabric, needle punch nonwoven fabric, water jet nonwoven fabric, stitch bond nonwoven fabric, and the like.
[0016]
Next, the fabrics A and B are stiffened by fusing the whole with heating . In the present invention, the fibers constituting the fabric A and B, a low-melting polymer is a core-sheath type composite (conjugate) fibers having a high melting point polymer in the core to the sheath, the one in which fused and fixed by heating This is because, in order to produce ultrapure water and the like, it is necessary to suppress the dropping of the adhesive and the distillation of the monomer as much as possible.
[0017]
Typical combinations of the high melting point component and the low melting point component include a high melting point polyester and a low melting point polyester, a high melting point polyamide and a low melting point polyamide, and a high melting point polyolefin and a low melting point polyolefin. A combination of a high-melting polyester and a low-melting polyester is preferable from the viewpoint of rigidity. The low melting point component can generally be easily obtained by using a high molecular weight copolymer, and the melting point difference can be obtained by changing the copolymerization ratio, adding a copolymerization component, changing the copolymerization component, stereoregularity or polymerization. It can be changed by changing the degree. Alternatively, a combination with a different polymer having a different melting point may be used. In the case of polyester, the melting point is generally lowered by 2 ° C. by copolymerization at 1 mol%. The monomer component copolymerized with the polyester is generally an acid component such as isophthalic acid or adipic acid. When polyethylene terephthalate (melting point: about 260 ° C.) is used as the high melting point component, polybutylene terephthalate (melting point: about 225 ° C.) or a copolymer obtained by copolymerizing a predetermined amount of an arbitrary monomer with polybutylene terephthalate is used as the low melting point component. For example, the melting point of polybutylene terephthalate (75 mol%)-isophthalate (25 mol%) copolymer is about 175 ° C.
[0018]
The above-mentioned thermoplastic synthetic fiber comprising a combination of both components is preferably used for at least a part of each of the fabrics A and B, and the low melting point components used for both fabrics preferably have the same melting point. This is because heat fusion can be integrated by a single heat treatment. As means other than fusion, there is sewing.
[0019]
The flow path material used in the present invention can withstand reverse osmosis pressure in the range of 0 to 200 kg / cm ² , and the flow path channel does not sink even if it is operated for a long time by the pressure in the range. .
[0020]
In the liquid separation membrane module of the present invention, the separation membrane is formed in a bag shape, provided with a permeate flow path material inside, and the separation membrane wound around the water collection pipe so that one end of the inside communicates with the water collection pipe It can be suitably used for a spiral separation membrane element having It is preferable that the permeated water channel material has grooves parallel to each other on the inner side.
[0021]
In the present invention, the grooves parallel to each other of the permeate flow channel material need to exist inside the permeate flow channel material. The inside of the permeated water channel material is the inside of the channel material that does not directly contact the back surface of the reverse osmosis membrane. If there are grooves parallel to each other at the part where the reverse osmosis membrane contacts, the reverse osmosis membrane will sink into this groove by applying pressure during reverse osmosis membrane separation, block the flow path, The road resistance will increase. In addition, when operated under high pressure for a long time, the reverse osmosis membrane is deformed, the reverse osmosis membrane is damaged, and the performance is lowered.
[0022]
The permeate channel material of the reverse osmosis membrane of the present invention is a practical liquid separation membrane module capable of maintaining the reverse osmosis membrane performance by suppressing the increase in channel resistance due to the depression in the groove and the deformation of the reverse osmosis membrane. Can be realized.
[0023]
In addition, in order to realize a permeate channel material having grooves parallel to each other on the inside, a sheet having a tight and dense structure on the groove surface of the permeate channel material of single tricot or double tricot knitting that has been used conventionally. Are preferably combined into a two-layer or three-layer structure.
[0024]
As the two-layer laminated structure, for example, as shown in FIG. 1, a flat cloth (for example, a plain woven fabric) 3 is fused and integrated on an uneven surface of a single tricot knitted fabric 2 to form a flow path material 1. ing. As another example, flow fabric 4 is formed by fusing and integrating flat fabrics (for example, plain woven fabrics) 3 and 7 on the concave and convex surfaces on both sides of a double tricot knitted fabric 5.
[0025]
The reverse osmosis membrane is assembled on the flow path materials 1 and 4 so that the dense membrane surface side faces the flow path material (FIGS. 3 to 4).
[0026]
Next, FIGS. 5 and 6 illustrate a spiral type liquid separation membrane module using the above-described flow path material.
[0027]
Reference numeral 11 denotes a fluid separation element, and reference numeral 12 denotes a cylindrical container that houses the fluid separation element 11. One end of the fluid separation element 11 is sealed in the cylindrical container 12 by a V-shaped sealing material 13, and the permeate discharge pipe 14 at the other end is projected to the outside of the cylindrical container 12. The cylindrical container 12 is provided with a stock solution supply pipe 15 on the open side wall of the V-shaped sealing material 13 and a stock solution discharge pipe 16 on the other side wall.
[0028]
As shown in FIG. 6, the liquid separation element 11 has a permeate discharge pipe 14 composed of a hollow pipe having a small hole 17 at the center, and an envelope-shaped reverse osmosis membrane 19 is wound around the outside in a spiral shape. Yes. The envelope-shaped reverse osmosis membrane 19 has a permeate passage material 20 according to the present invention inserted therein and communicated with the inside of the permeate discharge pipe 14 with its open end facing the small hole 17. Further, a stock solution channel material 21 is interposed between the outer surfaces of the envelope-shaped reverse osmosis membrane 19 wound in a spiral shape. Reference numeral 18 denotes a sealing portion.
[0029]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0030]
[Example 1]
A high melting point polyester (polyethylene terephthalate: melting point about 260 ° C.) is placed in the core component (70% by weight), and a low melting point polyester (polybutylene terephthalate (75 mol%)-isophthalate (25 mol%) copolymer (melting point about 175 ° C.) was placed in the sheath component (30% by weight), and a filament yarn having a total fineness of 70 denier and 17 filaments was prepared. Using this yarn, a single tricot knitting was knitted (38 wales / inch, 45 courses / inch).
[0031]
Next, a plain weave (warp yarn) having a total fineness of 50 denier, a filament number of 12: the low-melting-point polyester as a sheath and the high-melting-point polyester as a core on the surface (uneven surface) having grooves parallel to each other of the knitted fabric. Density: 102 yarns / inch, weft density: 74 yarns / inch, basis weight 35 g / m ² ). Next, the whole was stiffened by heat treatment at 185 ° C. for 5 minutes, and the two layers were fused to form a permeate channel material.
[0032]
On the other hand, an aromatic polyamide-based composite membrane (a membrane obtained by interfacial polycondensation of trimesic acid chloride and m-phenylenediamine, manufactured by Nitto Denko Corporation) is prepared, and the above-mentioned flow path material is arranged on the separation membrane surface, and FIG. A heat-resistant spiral separation membrane module (membrane area 6.5 m @ 2) was manufactured as shown in FIGS.
[0033]
When 5.8% saline was pressurized to 9 MPa and a reverse osmosis membrane permeation experiment was conducted at an outlet flow rate of 5 L / min, 25 ° C., and pH 7, the reverse osmosis membrane performance 60 minutes after the operation had a rejection rate of 99. It was 75% and the permeated water amount was 0.72 m ³ / m ² / day. The surface of the reverse osmosis membrane after the experiment was not observed after the sinking into the permeate channel material, and no damage was observed.
[0034]
[Comparative Example 1]
A single tricot knitted fabric using a polyester multifilament having a low-melting polyester as a sheath and a high-melting polyester as a core used in Example 1 is made rigid by heat treatment to obtain a permeate passage material (yarn diameter 70 denier, wale 38). Book / 1 inch, 45 courses / inch). A plain fabric is not laminated on the channel material. When the reverse osmosis membrane permeation experiment of Example 1 was performed using one sheet of this flow path material, the reverse osmosis membrane performance 60 minutes after the operation was a blocking rate of 99.52% and the permeated water amount was 0.51 m ³ / m. ² / day. The surface of the reverse osmosis membrane after the experiment was observed after depression in the groove of the permeate channel material, and membrane damage due to this was observed.
[0035]
Example 1 and Comparative Example 1 use the same reverse osmosis membrane, and the only difference is the permeate channel material. The low blocking rate after the experiment in Comparative Example 1 is due to the fact that the reverse osmosis membrane is damaged when the reverse osmosis membrane sinks into the groove of the permeate flow channel material. This is because the flow path resistance is increased because the flow path is blocked by the depression.
[0036]
[Example 2]
Plain weave of 50 denier high melting point polyester on both sides of a permeate flow path material (yarn diameter 50 denier, 38 wales / inch, 45 courses / inch) with double tricot knitting made in Example 1 impregnated with epoxy resin (Example) The reverse osmosis membrane was installed on the permeate flow path material in which three layers were bonded together with an epoxy resin which is a thermoplastic resin and the three layers were adhered. When a reverse osmosis test similar to that of Example 1 was performed, the reverse osmosis membrane performance 60 minutes after the operation was 99.73% with a rejection rate of O.O. It was 74 m ³ / m ² / day. The surface of the reverse osmosis membrane after the experiment was not observed after the sinking into the permeate channel material, and no damage was observed.
[0037]
[Comparative Example 2]
Permeated water channel material (yarn diameter) in which a double tricot knitted fabric was formed using a polyester multifilament yarn of normal type having a total fineness of 50 denier and 12 filaments used in Example 1, and impregnated with an epoxy resin. 50 denier, 38 wales / inch, 45 courses / inch). A plain fabric is not laminated on the channel material. Using this single channel material, the reverse osmosis membrane permeation experiment of Example 1 was performed. As a result, the reverse osmosis membrane performance 60 minutes after the operation was found to have a rejection rate of 99.47% and a permeated water amount of O.D. It was 48 m ³ / m ² / day. The surface of the reverse osmosis membrane after the experiment was observed after depression in the groove of the permeate channel material, and membrane damage due to this was observed.
[0038]
【The invention's effect】
According to the present invention, a practical spiral-type separation membrane capable of maintaining reverse osmosis membrane performance by suppressing increase in channel resistance and deformation of the reverse osmosis membrane due to the depression of the reverse osmosis membrane into the groove of the permeate channel material Mold modules can be provided.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view of a flow path material according to Embodiment 1 of the present invention.
FIG. 2 is a conceptual cross-sectional view of a flow path material of Example 2 of the present invention.
FIG. 3 is a conceptual cross-sectional view in which a reverse osmosis membrane is incorporated on the channel material of Example 1 of the present invention.
FIG. 4 is a conceptual cross-sectional view in which a reverse osmosis membrane is incorporated on a flow path material of Example 2 of the present invention.
FIG. 5 is a cross-sectional view of a spiral type liquid separation membrane module according to an embodiment of the present invention.
6 is a cross-sectional view taken along the line II of FIG.
FIG. 7 is a conceptual cross-sectional view of a single tricot knitted fabric used in a conventional channel material.
FIG. 8 is a conceptual cross-sectional view of a double tricot knitted fabric used in a conventional channel material.
FIG. 9 is a conceptual cross-sectional view after operating for a long time with a reverse osmosis membrane incorporated on a single tricot knitted fabric used in a conventional channel material.
FIG. 10 is a conceptual cross-sectional view after a reverse osmosis membrane is incorporated on a double tricot knitted fabric used for a conventional channel material and operated for a long period of time.
[Explanation of symbols]
1, 4 Channel material 2, 31 Single tricot knitted fabric 5, 32 Double tricot knitted fabric 3, 6, 7 Plain fabric 8, 9, 33, 34 Reverse osmosis membrane 11 Fluid separation element 12 Cylindrical container 13 V-shaped sealing material 14 Permeate discharge pipe 15 Stock solution supply pipe 16 Stock solution discharge pipe 17 Small hole 18 Sealing portion 19 Reverse osmosis membrane 20 Permeate channel material 21 Stock solution channel material

Claims (5)

In the liquid separation membrane module in which the flow path material supporting the back side of the reverse osmosis membrane that receives the stock solution is incorporated,
The flow path material is formed by laminating a fabric A having a concavo-convex structure in a cross section and a flat fabric B on the concavo-convex surface of the fabric A,
The fibers constituting the fabrics A and B are core-sheath composite fibers having a low melting point polymer as a sheath and a high melting point polymer as a core, and the fabrics A and B are fused together by heating. Is stiffened by
The fabrics A and B are integrated by fusion ,
A liquid separation membrane module, wherein a space formed by the concave portion of the fabric A and the flat fabric B forms a flow channel that does not sink due to a pressure required for reverse osmosis.   2. The liquid separation membrane module according to claim 1, wherein when the fabric B is laminated on one side of the fabric A, there are two layers, or when the fabric B is laminated on both sides of the fabric A, there are three layers.   The liquid separation membrane module according to claim 1 or 2, wherein the fabric A is a tricot knitted fabric having an uneven structure, and the fabric B is a woven fabric or a nonwoven fabric.   The liquid separation membrane module according to any one of claims 1 to 3, wherein the fabric A is a single tricot knitted fabric, and the fabric B laminated on the one-sided uneven surface of the knitted fabric is a woven fabric or a nonwoven fabric.   The liquid separation membrane module according to any one of claims 1 to 3, wherein the fabric A is a double tricot knitted fabric, and the fabric B laminated on the uneven surfaces on both sides of the knitted fabric is a woven fabric or a nonwoven fabric.

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