JP2019118841A - Membrane element and membrane separator - Google Patents

Abstract

To provide a membrane element capable of decreasing kinds of components.SOLUTION: A filter membrane 22 is joined to at least one surface of a flow path material 21. The flow path material 21 is composed of nonwoven fabric having a large number of fibers 24. A cavity 32, along which permeate after passing through the filter membrane 22, is disposed between the fibers 24. At least a part of the fibers 24 out of the fibers 24 constituting the flow path material 21 has a lower softening point than a softening point of the filter membrane 22.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a membrane element used for separation of sludge and treated water in a field called, for example, a membrane separation activated sludge process (MBR) and a membrane separation apparatus provided with the membrane element.

  Conventionally, as a membrane element of this type, for example, as shown in FIG. 9, there is a membrane element in which filtration membranes 102 are joined to both sides of a resin filter plate 101, and the peripheral edge part 102a of filtration membranes 102 is thermally welded or ultrasonicated. It is fixed to the filter plate 101 by welding. A permeated fluid flow path (not shown) is formed between the filter plate 101 and the filtration membrane 102 and in the filter plate 101, and the permeated liquid outlet 103 communicating with the permeated fluid flow path is at the upper edge of the filter plate 101. It is provided.

  As indicated by a solid line in FIG. 10, a plurality of the above-described membrane elements 104 are arranged at predetermined intervals in a membrane case (not shown).

  According to this, when performing the filtration operation, the liquid to be treated passes through the filtration membrane 102 from the primary side to the secondary side and is filtered, and then flows as the permeated liquid 105 through the permeated liquid flow path, and the permeated liquid is collected. It is taken out from the outlet 103 to the outside. In addition, when the filtration operation is stopped and the membrane element 104 is backwashed, water for backwashing is injected from the permeated liquid outlet 103 into the permeated liquid flow path. Thereby, the water for backwashing passes through the filtration membrane 102 from the secondary side to the primary side, and the filtration membrane 102 is backwashed.

  In such a membrane element 104, the entire filtration membrane 102 is not fixed to the filter plate 101, and only the peripheral portion 102a of the filtration membrane 102 is welded to the filter plate 101. During the washing, as shown by the phantom line in FIG. 10, the filtration membrane 102 may bulge outward (primary side) and contact the filtration membrane 102 of the next membrane element 104. As described above, when the filtration membranes 102 of the membrane elements 104 adjacent to each other bulge and contact, there is a possibility that the effect of the backwashing may be reduced. Further, by introducing the backwashing water to the secondary side for a long time, there is a possibility that the filtration membrane 102 bulges outward, and the welded portion of the peripheral portion 102 a of the filtration membrane 102 is opened.

  In order to solve such a problem, as shown in FIG. 11, a first filtration membrane 111, a second filtration membrane 112, and a drainage woven fabric 113 provided between the both filtration membranes 111 and 112. A membrane element having a first adhesive net 114 for bonding the first filtration membrane 111 and the drainage woven fabric 113, and a second adhesive net 115 for bonding the second filtration membrane 112 and the drainage woven fabric 113 There are 116. The drainage woven fabric 113 is a three-dimensional spacer fabric (spacer fabric) knitted to form a loop.

  By laminating the drainage woven fabric 113 and the adhesive nets 114 and 115 between the first filtration membrane 111 and the second filtration membrane 112 and rolling them with a heating roll, the adhesive nets 114 and 115 become temporary. And the first filtration membrane 111 and the drainage woven fabric 113 are adhered via the first adhesive net 114, and the second filtration membrane 112 and the drainage woven fabric via the second adhesive net 115. And 113 are adhered, and the membrane element 116 is completed.

  The above-mentioned membrane element 116 is described, for example, in Patent Document 1 below.

  Further, in Patent Document 2 below, a liquid membrane material resin (hereinafter referred to as "dope") dissolved in a solvent is directly applied to one side or both sides (faces) of the spacer fabric, and the filtration membrane is separated by phase separation method. It is described to form a layer on the face of the spacer fabric.

Special table 2011-519716 WO 2006/015461 A1

  However, in the conventional method described in Patent Document 1, as shown in FIG. 11, in order to manufacture the membrane element 116, the drainage woven fabric 113, the filtration membranes 111 and 112, and the adhesive nets 114 and 115 are required. Therefore, there is a problem that the types of parts constituting the membrane element 116 increase.

  Moreover, about the said patent document 2, although the interior space of a spacer fabric becomes a passage of the permeated fluid which permeate | transmitted the filtration membrane layer, when the dope is directly apply | coated to the face of a spacer fabric, when the viscosity of dope is low, The dope may intrude into the interior space of the spacer fabric and solidify, which may impede the flow of permeate inside the spacer fabric.

  An object of the present invention is to provide a membrane element and a membrane separation apparatus capable of reducing the types of components.

In order to achieve the above object, in the membrane element according to the first aspect of the present invention, a filtration membrane is bonded to at least one side of a flow path material,
The flow path material is made of a non-woven fabric having a large number of fibers, and between the fibers, there is a space through which the permeated liquid that has permeated the filtration membrane flows
At least some of the fibers constituting the flow path material have a softening point lower than that of the filtration membrane.

  According to this, the filtration membrane is disposed on the flow path material, and heating is performed to a temperature equal to or higher than the softening point of at least a part of the fibers of the non-woven fabric forming the flow path material. The filtration membrane is joined to the flow path material because at least a part of the fibers is softened and entangled in the filtration membrane. As described above, since the membrane element can be manufactured by the flow path material and the filtration membrane, there is no need to interpose an adhesion member such as an adhesive net between the flow path material and the filtration membrane, and thus the membrane element Can reduce the types of parts that make up the

  In addition, as described above, the heating temperature is lower than the softening point temperature of the filtration membrane and is higher than the softening point of the fibers of at least part of the non-woven fabric of the flow path material. It is possible to prevent the pore size distribution of the membrane from changing.

  In the membrane element according to the second aspect of the present invention, the flow path material has, on the surface, the first fiber having a softening point lower than the softening point of the filtration membrane, and also has the inside higher than the softening point of the first fiber It has a second fiber having a softening point.

  According to this, the filtration fiber is arranged on the surface of the flow path material, and the first fibers on the surface of the flow path material are softened by heating to a temperature higher than the softening point of the first fiber on the surface of the flow path material Then, in order to be entangled in the filtration membrane, the filtration membrane is joined to the surface of the flow path material.

  Under the present circumstances, since the softening point of the 2nd fiber in the inside of channel material is higher than the softening point of the 1st fiber on the surface of channel material, it can prevent that the 2nd fiber is softened. . Thereby, it can suppress that a 2nd fiber softens and the thickness of a flow-path material reduces large.

In the membrane element according to the third aspect of the present invention, the surface of the non-woven fabric constituting the flow path material has a softening point lower than that of the filtration membrane,
The inside of the non-woven fabric of the flow path material has a softening point higher than that of the surface.
According to this, the filtration membrane is disposed on the surface of the flow path material, and the fiber surface of the flow path material is softened and entangled in the filtration membrane by heating to a temperature higher than the softening point of the surface of the flow path fiber. Therefore, the filtration membrane is bonded to the surface of the flow path material.

  Under the present circumstances, since the softening point inside the fiber of flow-path material is higher than the softening point of the surface of a fiber, it can prevent that the whole fiber softens. Thereby, it is possible to suppress that the entire fiber is softened and the thickness of the flow passage material is significantly reduced.

  In the membrane element in the fourth invention, the filtration membrane is bonded to both the front and back sides of the flow path material.

  In the membrane element in the fifth invention, the filtration membrane has a porous membrane made of PTFE.

The sixth aspect of the present invention is a membrane separation apparatus comprising the membrane element according to any one of the first to fifth aspects of the present invention,
A support member for supporting a plurality of membrane elements;
The support member has a water collection space inside,
The end of each membrane element is inserted into the water collection space,
The permeate flows into the water collection space of the support member through the space of the flow path material.

  According to this, in the state where the membrane separation apparatus is immersed in the liquid to be treated, the liquid to be treated passes through the filtration membrane of the membrane element from the primary side to the secondary side by performing the filtration operation. Thereafter, as a permeated liquid, it flows into a minute void inside the flow passage material, passes through the minute void in the flow passage material, and flows out to the water collection space of the support member.

  As described above, according to the present invention, since a membrane element can be manufactured from the flow path material and the filtration membrane, a member dedicated to adhesion such as an adhesive net is not necessary, and the type of parts constituting the membrane element It can be reduced.

It is a front view of a membrane separation device using a plurality of membrane separation equipment in a 1st embodiment of the present invention. It is a perspective view of a membrane separation apparatus equally. It is a sectional view of a membrane separation apparatus equally. It is a partially cutaway perspective view which shows the structure of the membrane element of a membrane separation apparatus equally. It is the schematic diagram which expanded the cross section of the membrane element equally. It is a partially expanded perspective view of the flow-path material of a membrane element equally. It is the schematic diagram which expanded the cross section of the membrane element in the 2nd Embodiment of this invention. It is the schematic diagram which expanded the cross section of the fiber of the flow-path material of the membrane element in the 3rd Embodiment of this invention. It is a front view of the conventional membrane element. It is a side view of a membrane element equally, and shows a state where a plurality of membrane elements are arranged at predetermined intervals. It is a partially cutaway perspective view which shows the structure of another conventional membrane element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment
In the first embodiment, as shown in FIG. 1, 1 is an immersion-type membrane separation apparatus for performing membrane filtration, which is immersed in a liquid 2 to be treated such as organic drainage and installed in a treatment tank 3 ing. The membrane separation device 1 has a plurality of membrane separation devices 5 (also referred to as a membrane filtration module) stacked vertically, and a diffuser 6 provided at the lowermost stage.

  As shown in FIGS. 2 and 3, the membrane separation apparatus 5 includes a pair of left and right water collecting cases 11 (an example of a support member), and a plurality of membrane elements 12 supported between the two water collecting cases 11. It has a pair of front and rear connection plates 13. The water collection case 11 is a hollow member having a water collection space 15 inside. Further, the connecting plate 13 is provided between the front end and the rear end of the two water collecting cases 11 respectively.

  The water collection space 15 in the water collection case 11 of the lower membrane separation apparatus 5 and the water collection space 15 in the water collection case 11 of the upper membrane separation apparatus 5 are in communication with each other in the water collection case 11. It communicates by the port 16.

  A plurality of through holes elongated in the vertical direction are formed in the inner side wall 17 of the water collection case 11, and left and right ends of each of the membrane elements 12 are inserted into the respective through holes and rush into the water collection space 15.

  As shown in FIGS. 4 and 5, the membrane element 12 is, for example, a square sheet-like member, and has a flow path material 21 and filtration membranes 22 joined to both the front and back sides of the flow path material 21. There is.

  As shown in FIG. 6, the flow path material 21 is made of a non-woven fabric having a large number of fibers 24, and the permeating fluid 33 which has permeated through the filtration membrane 22 flows between the intricately intertwined fibers 24 like cobwebs. The air gap 32 is provided. The fibers 24 of the flow path material 21 have a softening point T2 lower than the softening point T1 of the filtration membrane 22.

  The softening point is a temperature at which a resin or the like softens and deforms, and, for example, ethylene vinyl acetate having a softening point T2 of about 55 ° C. to 90 ° C. as a material of the fibers 24 of the passage material 21 Copolymers (EVA) are used.

Further, the basis weight of the flow path material 21 is, for example, 300 to 600 g / m ² , and the thickness thereof is, for example, 1 to 3 mm.

  The filtration membrane 22 has a porous resin layer 22a (porous membrane) having a large number of micropores on the outer surface side and a resin layer support 22b such as a non-woven fabric for supporting the resin layer 22a on the inner surface side There is. For example, polytetrafluoroethylene (PTFE) is used for the porous resin layer 22a. Further, as a material of the resin layer support 22b, for example, polyethylene terephthalate (PET) having a softening point T1 of 260 ° C. to 280 ° C. (softening point T1 of the resin layer support 22 b) is used.

  Hereinafter, the operation in the above configuration will be described.

  When manufacturing the membrane element 12, the flow path material 21 is disposed between the pair of filtration membranes 22, and the three members of the flow path material 21 and the both filtration membranes 22 are inserted between the upper and lower heating rolls. And heat while compressing.

  At this time, by heating so that the temperature of the fibers 24 forming the flow path material 21 reaches the softening point T2 (that is, 55 ° C. to 90 ° C.), the fibers 24 of the flow path material 21 soften and filter In order to be entangled with the resin layer support 22 b of the membrane 22, the filtration membrane 22 is joined to both the front and back sides of the flow path material 21. In practice, since heat is transferred from the upper and lower heating rolls to the fibers 24 through the filtration membrane 22 during rolling, a heating temperature of 100 ° C. to 140 ° C. higher than T2 is used.

At this time, the filtration membrane 22 is joined at a number of contact points in contact with the fibers 24 of the flow path material 21. Further, as described above, the heating temperature is set to the temperature of the softening point T1 of the resin layer support 22b of the filtration membrane 22 (ie 260 ° C. to 280 ° C.) and the temperature of the softening point T2 of the fibers 24 of the flow path material 21 (ie 55 ° C). Because the temperature is in the range of 0 C to 90 C, it is possible to prevent the filtration membrane 22 from being softened. As a result, it is possible to prevent the pore size distribution of the filtration membrane 22 from being changed or to make the filtration membrane 22 have wrinkles.
As described above, since the membrane element 12 can be manufactured by the flow path material 21 and the filtration membrane 22, it is necessary to interpose a member dedicated to adhesion such as an adhesive net between the flow path material 21 and the filtration membrane 22. Can be eliminated, and the types of parts constituting the membrane element 12 can be reduced. In addition, the temperature at the time of heating the flow-path material 21 and the filtration film 22 by a heating roll as mentioned above is 100 degreeC-140 degreeC, Preferably it is 115 degreeC-125 degreeC.

  In addition, the membrane element 12 of the present invention is fused and the filtration membrane 22 is fused to the channel material 21 by heating, and the dope dissolved in the solvent as in the prior art is directly applied to the face of the spacer fabric to filter membrane layer. Therefore, the dope does not intrude into the minute air gaps 32 (internal space) in the flow path material 21 which is the passage of the permeated liquid 33 and solidify.

  A filtration operation is performed in a state in which the membrane separation device 5 provided with the flexible membrane element 12 manufactured in this manner is immersed in the liquid 2 to be treated as shown in FIGS. 1 to 3. . Thereby, the liquid 2 to be treated passes through the filtration membrane 22 of the membrane element 12 from the primary side to the secondary side and is filtered, and then flows into the minute gap 32 inside the flow path material 21 as the permeated liquid 33 The liquid flows out to the water collection space 15 in the water collection case 11 through the minute air gap 32 in the flow path material 21, and from the inside of the water collection case 11 of the uppermost membrane separation apparatus 5 through the communication hole 16. Taken out.

  In the first embodiment, the ethylene-vinyl acetate copolymer (EVA) is used as the material of the fibers 24 of the flow path member 21. However, the present invention is not limited to this. For example, polyethylene (PE) May be used.

Second Embodiment
In the second embodiment, as shown in FIG. 7, the flow path material 21 has a large number of first points having softening points T3 lower than the softening point T1 of the resin layer support 22b of the filtration membrane 22 on both front and back sides. The fibers 41 are provided therein, and a plurality of second fibers 42 having a softening point T4 higher than the softening point T3 of the first fibers 41 are provided inside.

  As a material of the first fiber 41, for example, an ethylene vinyl acetate copolymer (EVA) having a softening point T3 of about 55 ° C to 90 ° C is used. For the second fiber 42, polyethylene terephthalate (PET) having a softening point T4 of 260 ° C. or higher, for example, is used.

  The channel material 21 sprays the first fibers 41 on both the front and back sides of the nonwoven fabric 42A made of the second fibers 42 to form the layer 41A of the first fibers 41, thereby forming a single sheet-like member. Manufactured in

  Hereinafter, the operation in the above configuration will be described.

  When manufacturing the membrane element 12, the flow path material 21 is disposed between the pair of filtration membranes 22, and the three members of the flow path material 21 and the both filtration membranes 22 are inserted between the upper and lower heating rolls. And heat while compressing.

  At this time, the first fibers 41 of the flow path material 21 are softened by heating so that the first fibers 41 on both the front and back sides of the flow path material 21 reach the softening point T3 (that is, 55 ° C to 90 ° C). Then, in order to be entangled with the resin layer support 22 b of the filtration membrane 22, the filtration membrane 22 is joined to both the front and back sides of the flow path material 21.

  At this time, the filtration membrane 22 is joined at a number of contact points in contact with the first fibers 41 of the flow path material 21. Further, as described above, the heating temperature is set to the softening point T1 of the resin layer support 22b of the filtration membrane 22 (that is, 260 ° C. to 280 ° C.) and the softening point T3 of the first fiber 41 of the flow path material 21 (that is, 55 ° C.). Since the temperature is in the range of -90 ° C, the filtration membrane 22 can be prevented from being softened.

  Furthermore, since the softening point T4 of the second fiber 42 inside the flow path material 21 is higher than the softening point T3 of the first fibers 41 on both the front and back sides of the flow path material 21, the second fiber 42 is Can be prevented from softening. Thereby, it can suppress that the 2nd fiber 42 softens and the thickness of the flow-path material 21 reduces large.

  In the second embodiment, the front and back sides of the flow path material 21 are provided with a layer of the first fibers 41 having a softening point T3 lower than the softening point T1 of the resin layer support 22b of the filtration membrane 22. However, fibers having a softening point higher than the softening point T3 (for example, fibers of a material of polyethylene terephthalate) may be mixed in the layer of the first fiber 41 at a predetermined ratio.

  According to this, when the membrane element 12 is manufactured, the flow path material 21 is disposed between the pair of filtration membranes 22 and the flow path material 21 is heated when heated to the temperature of the softening point T3 of the first fiber 41. It is possible to prevent the front and back surfaces from melting and blocking the voids between the fibers of the resin layer support 22b of the filtration membrane 22 and the fine pores of the resin layer 22a.

In the second embodiment, the ethylene-vinyl acetate copolymer (EVA) is used as the material of the first fibers 41 of the flow path material 21. However, the present invention is not limited to this. For example, polyethylene ( PE) or the like may be used.
Third Embodiment
In the third embodiment, as shown in FIG. 8, the fibers 24 constituting the flow path material 21 have a core-sheath structure, and a sheath of a surface covering the core 24 a inside and the outer periphery of the core 24 a And 24b. The sheath 24b is made of a first resin, and the core 24a is made of a second resin. The softening point T6 of the core 24a made of the second resin is higher than the softening point T5 of the sheath 24b made of the first resin.

  As a material of the first resin, for example, an ethylene-vinyl acetate copolymer (EVA) having a softening point T5 of about 55 ° C. to 90 ° C. is used. Moreover, for example, polyethylene (PE) having a softening point T6 of 80 ° C. to 120 ° C. is used as the second resin.

  The flow path member 21 is made of, for example, PE of the core 24a and EVA of the sheath 24b by simultaneously blowing out the molten PE resin from the outside of the metal double pipe, for example. A sheet of adhesive net made of fibers 24 is manufactured.

  Hereinafter, the operation in the above configuration will be described.

  When manufacturing the membrane element 12, the flow path material 21 is disposed between the pair of filtration membranes 22, and the three members of the flow path material 21 and the both filtration membranes 22 are inserted between the upper and lower heating rolls. And heat while compressing.

  At this time, the sheath 24b of the fiber 24 of the flow path material 21 is softened by heating so that the sheath 24b of the fiber 24 of the flow path material 21 reaches the softening point T5 (that is, 55.degree. C. to 90.degree. C.). In order to be entangled with the resin layer support 22 b of the membrane 22, the filtration membrane 22 is joined to both the front and back sides of the flow path material 21.

  At this time, the filtration membrane 22 is joined at a number of contact points in contact with the fibers 24 of the flow path material 21. Further, as described above, the heating temperature is set to the softening point T1 of the resin layer support 22b of the filtration membrane 22 (that is, 260 ° C. to 280 ° C.) and the softening point T5 of the sheath 24b of the fibers 24 of the flow path material 21 (that is, 55 ° C.). Since the temperature is in the range of -90 ° C, the filtration membrane 22 can be prevented from being softened.

  Furthermore, since the softening point T6 of the second resin constituting the core 24a of the fibers 24 of the flow path material 21 is higher than the softening point T5 of the first resin constituting the sheath 24b of the fibers 24, It can prevent that the fiber 24 of the flow-path material 21 softens. Thereby, it can be suppressed that the fibers 24 of the flow path material 21 are softened and the thickness of the flow path material 21 is significantly reduced.

  In the third embodiment, the passage material 21 is made of the fiber 24 covered with the resin having the softening point T5 lower than the softening point T1 of the resin layer support 22b of the filtration membrane 22. At 24, a fiber having a softening point higher than the softening point T5 (for example, a fiber made of polyethylene) may be blended at a predetermined ratio.

  According to this, when the membrane element 12 is manufactured, the flow path material 21 is disposed between the pair of filtration membranes 22 and heated to a temperature higher than the softening point T5 of the sheath 24 b of the fibers 24 of the flow path material 21. Thus, it is possible to prevent the sheath 24b from melting and blocking the voids between the fibers of the resin layer support 22b and the fine pores of the resin layer 22a of the filtration membrane 22.

  In the third embodiment, the ethylene-vinyl acetate copolymer (EVA) is used as the material of the sheath 24b of the fiber 24 of the flow path material 21, and PE is used as the material of the core 24a. Instead, for example, polyethylene (PE) or polyacrylic acid resin may be used as the material of the sheath 24b, and copolyester may be used as the material of the core 24a.

  In each of the above embodiments, the filtration membranes 22 are respectively joined to the front and back sides of the flow path material 21. However, the filtration membrane 22 is joined to any one of the front and back sides of the flow path material 21 and the other side is made watertight. It is also good.

  In each of the above embodiments, the channel material 21 before bonding the filtration membrane 22 is provided with a groove or a cut in the left-right direction (direction between both water collecting cases 11 in FIG. 2) during molding or post processing. The permeated liquid 33 may easily flow toward the water collection case 11.

  Although each softening point T1 to T6 is used as an index in each of the above embodiments, a melting point may be used as an index instead of the softening points T1 to T6. Even when the melting point is used as an index, the same high-low relationship of temperature as the softening points T1 to T6 is established.

  Further, the materials and numerical values of the ethylene-vinyl acetate copolymer, polyethylene, polyethylene terephthalate, polytetrafluoroethylene and the like shown in the above-mentioned respective embodiments are merely examples, and the present invention is not limited to these.

5 Membrane separation equipment 11 Water collection case (support member)
12 membrane element 15 water collection space 21 flow path material 22 filtration membrane 24 fiber 32 minute air gap 33 permeated liquid 41 first fiber 42 second fiber T1 softening point T2 of resin layer support of filtration membrane fiber of flow path material Softening point T3 Softening point T1 of first fiber Softening point T2 of second fiber Softening point of sheath of fiber T6 Softening point of core of fiber

Claims (6)

A filtration membrane is bonded to at least one side of the flow path material,
The flow path material is made of a non-woven fabric having a large number of fibers, and between the fibers, there is a space through which the permeated liquid that has permeated the filtration membrane flows
A membrane element characterized in that at least a part of fibers among the fibers constituting the flow path material have a softening point lower than that of a filtration membrane. The flow path material has, on the surface, a first fiber having a softening point lower than that of the filtration membrane, and, inside, a second fiber having a softening point higher than the softening point of the first fiber. The membrane element according to claim 1, characterized in that it comprises. The surface of the non-woven fabric constituting the channel material has a softening point lower than that of the filtration membrane,
The membrane element according to claim 1, wherein the interior of the non-woven fabric constituting the flow passage material has a softening point higher than the softening point of the surface. The membrane element according to claim 2 or 3, wherein the filtration membrane is bonded to both the front and back sides of the flow path material. The membrane element according to any one of claims 1 to 4, wherein the filtration membrane has a porous membrane made of PTFE. A membrane separation apparatus comprising the membrane element according to any one of claims 1 to 5,
A support member for supporting a plurality of membrane elements;
The support member has a water collection space inside,
The end of each membrane element is inserted into the water collection space,
A membrane separation apparatus characterized in that a permeated liquid flows into a water collection space of a support member through an air gap of a flow path material.

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