JPH0838859A - Membrane module of membrane separator - Google Patents

Abstract

PURPOSE:To enable backwashing operation without reducing an effective membrane area. CONSTITUTION:Sheet like membranes 6, 6 are arranged on both sides of a transmitted water passage spacer 5 and the outer peripheral edges of both membranes are sewen on the transmitted water passage spacer 5 by thread to fix the membranes and both membranes are also sewn on the inside of the outer peripheral edges thereof by thread to be fixed to constitute a membrane leaf 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane module of a membrane separation device.

[0002]

2. Description of the Related Art As a membrane module using a flat membrane, a spiral type and a plate and frame type are known.
In many cases, these membrane modules use RO membranes or UF membranes and are used under the conditions of cross-flow filtration. This focuses on suppressing the concentration polarization layer formed on the membrane surface by the crossflow flow velocity to improve the filtration efficiency. Further, it is known that crossflow filtration is effective as a concentration polarization layer suppression method for separating ions and organic substances. However, in a raw water system in which fine particles and the like coexist, the fine particles accumulate on the film surface, and a thick cake layer is formed on the film surface. Generally, the operation of cross-flow filtration is not effective in suppressing this cake layer. To remove the cake layer in this way, a backwashing operation in which the permeated water flows back from the permeated water side to the raw water side is effective.

[0003]

However, when the backwashing operation is applied to a spiral-type or plate-and-frame type membrane module using a flat membrane, stress concentrates on the fixed portion fixing the membrane, Will be damaged. Therefore, the backwashing operation cannot be directly applied to the conventional membrane module. In the case of a spiral wound type membrane module, it may be possible to apply a corrugated plate-shaped raw water flow path spacer to enable backwashing. In this case, the contact portion between the raw water flow path spacer and the membrane Area becomes large and the effective membrane area is reduced because filtration is not possible in this area. Further, in the flat sheet membrane module, it is possible to fix the membrane surface by welding or bonding to the supporting filter plate, but with such a structure, the stress of the membrane under the pressure on the secondary side is fixed to each fixing portion. Since it can be dispersed, the backwashing operation can be performed, but on the other hand, there is a drawback that the area of the fixed portion becomes large and the effective membrane area decreases. Therefore, the present invention is intended to provide a membrane module that can be backwashed without reducing the effective membrane area.

[0004]

The present invention has been proposed in view of the above, and sheet-like membranes are arranged on both sides of a permeated water flow path spacer, and both membranes are fixed to the permeated water flow path spacer by a stitching means. It was done.

[0005]

Since both membranes are fixed to both sides of the permeate flow passage spacer by the suturing means, the cleaning liquid is pressure-fed to the permeate flow passage, and the cleaning liquid is permeated from the inner surface to the outer surface of the membrane, whereby the outer surface of the membrane is attached. The kimono can be peeled off and removed, and even if the stress of peeling the membrane from the permeate flow path spacer acts during this backwashing operation, this stress is dispersed in a wide range fixed by the suturing means. Therefore, it is possible to prevent the membrane from being separated from the permeate flow path spacer.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a spiral wound type membrane module 4 in which a membrane leaf 2 is polymerized and wound around a water collecting pipe 1 around a raw water flow path spacer 3 and FIG. 2 is a cross section of the membrane leaf 2. It is a figure.

The membrane leaf 2 is composed of a long net-like permeate flow channel spacer 5 made of a tricot knitted fabric, and membranes 6 and 6 arranged on both sides of the permeate flow channel spacer 5 so as to overlap each other. Both membranes 6 and 6 are sewn to both surfaces of the permeate flow path spacer 5 by a thread 7 which is a stitching means.

The positions where the membranes 6 and 6 are sewn to the permeate flow channel spacer 5 are the outer peripheral edge and the outer peripheral edge except one edge portion (winding base end) connecting the membrane leaf 2 to the water collecting pipe 1. It is the inner part of the periphery. Specifically, the long side portions of the membranes 6 and 6 facing each other are sewn with a thread 7 while the permeate flow path spacer 5 is sandwiched between the membranes 6 and 6, and the long side suture fixing portion 7 is sewn.
In addition, the short side portion, which is the winding end, is sewn with the thread 7 with the permeated water flow path spacer 5 sandwiched therebetween to form the short side sewn fixed portion 7b. Further, in the inner side of the sewn outer peripheral edge portion, in other words, in the region surrounded by the long side suture fixing portion 7a and the short side suture fixing portion 7b, the short side suture fixing portion 7b is parallel to the long side suture fixing portion 7a. The inner suture fixing portion 7c is sewn.

In this way, when the thread 7 is sewn through the three membranes 6, 6 and the permeated water flow path spacer 5 while the permeated water flow path spacer 5 is sandwiched between the both membranes 6, 6, The three parts are firmly fixed by the suture fixing portions 7a, 7b, 7c. Further, the portion not sewn becomes the permeate flow channel 8,
This permeate flow channel 8 extends along the longitudinal direction of the membrane leaf 2 and is closed at one end by stitching but is not sewn at the other end, and is opened at the winding base end edge of the membrane leaf 2. Therefore, when the membrane leaf 2 is wound around the water collection pipe 1, it is wound around the water collection pipe 1 from the end (proximal end) where the opening of the permeated water flow passage 8 is located, and the opening of each permeated water flow passage 8 is collected. The water pipe 1 is communicated.

Permeate flow path spacer 5 and membranes 6 on both sides
When 6 is sewn with a thread 7, a hole may be opened when the sewing machine needle penetrates the thread 7 in three directions, and a leak may occur from this hole. However, in the case of containing SS such as sludge membrane separation treatment, even if a slight leak occurs at the beginning of operation, the sludge adheres to the membrane surface and blocks the holes. Therefore, the leak from the suture hole does not hinder the use.

When used for water-based membrane separation treatment,
The thread 7 or the film 6 may be made of a material having a heat-sealing property, and may be heat-treated (for example, heated to about 60 degrees Celsius) to close the suture hole by heat-sealing. Examples of the material of the heat-fusible thread 7 include polyethylene and polypropylene, and examples of the material of the membrane 6 include polysulfone, polyethylene, polyamide, and polyvinyl alcohol.

When the spiral wound type membrane module 4 having such a structure is filled in a cylindrical pressure vessel and raw water is pressed in from one end, the raw water passage spacer is wound with the membrane leaf 2 in a state of being polymerized with the membrane leaf 2. Raw water enters the space 3 and the water of the raw water permeates the membrane 6 and enters the permeate flow path 8. A drainage pipe is connected to the water collection pipe 1. Therefore, the permeated water that has entered the permeated water channel 8 is collected in the water collection pipe 1 and drained from the drain pipe.

Since the permeate flow channel 8 is formed by stitching with the thread 7 along the flow direction of the permeate flowing toward the water collecting pipe 1, it does not interfere with the flow of the permeate. Since one end of the permeate flow channel 8 is not sewn, the permeate flowing through the permeate flow channel 8 smoothly flows into the water collecting pipe 1.
Therefore, even if the membranes 6 and 6 on both sides are fixed to the permeated water flow path spacer 5 by stitching them with the thread 7, the permeated water flow is not blocked or resistance is not generated.

When a sludge-based raw water is separated by a membrane, a cake layer is easily formed on the membrane surface, but when the cake layer is formed,
A backwashing operation is performed in which the cleaning liquid is pressure-fed from the water collecting pipe 1 side and the cleaning liquid is permeated from the inner surface to the outer surface of the membrane 6 to peel off the cake layer attached to the outer surface of the membrane 6. Since the cleaning liquid permeates the membrane 6 in the direction opposite to the permeated water, the cake layer is easily peeled off from the outer surface of the membrane 6 and removed.

When this backwashing operation is carried out, the pressure of the cleaning liquid in the direction of peeling from the permeate flow path spacer 5 acts on the membrane 6, but the membrane in this embodiment is not limited to the outer peripheral portion by the 6 threads 7, and Since the inside is also sewn and fixed linearly to the permeate flow path spacer 5, the pressure of the cleaning liquid is dispersed over the entire length of the suture fixing portions 7a, 7b, 7c.
Therefore, it is possible to prevent the film 6 from being damaged.

In the above-mentioned embodiment, the outer peripheral edge of the membrane 6 and the inner side thereof are sewn with the thread 7, but in the present invention, the outer peripheral edge of the membrane 6 is sealed by a sealing means such as heat, adhesion or high frequency welding.
May be fixed to the permeate flow path spacer 5 in a watertight manner.

The membrane module 4 according to the present invention is not limited to the spiral type, but may be a flat membrane laminated type. For example, the flat membrane laminated type membrane module 4'shown in FIG. 3 has flat membranes 6 and 6 of the same size on both sides of a flat and square net-shaped permeate flow path spacer 5 made of a tricot knitted fabric or the like.
Are sewn, and the four peripheral edges thereof are sewn together with the thread 7, and the inside of the four-circumference stitched portion is also sewn with the thread 7. In this case, the water passage ports 9 are opened in the diagonal corners located inside the four-circle stitching portion, and the stitches are sewn along the flow direction of the permeated water flowing toward these water passage ports 9.

That is, the line connecting both water passages 9 and 9 at the shortest distance is sewn to form a straight stitching fixed portion 7d, and the curvature on both sides of this straight stitching fixed portion 7d gradually increases toward the outside. The curved suture fixing portion 7e is formed by suturing in an increasing curved shape. As a result, an elongated permeated water channel 8 that smoothly connects both water passage ports 9 and 9 is partitioned by the stitched portions 7d and 7e between the membranes 6 and 6, and when permeated water flows through these permeated water channels 8. The sewn portions 7d and 7e do not resist the flow of permeated water.

In order to stack the membrane modules 4'having such a structure, two adjacent membrane modules 4 ', 4'
An elastic gasket 11 for maintaining a predetermined water passage interval 10 is interposed between the two. The gasket 11 is a triangular or quadrangular member, and has an opening 12 of the same size that communicates with the water passage 9 as shown in FIG. Then, a plurality of membrane modules 4 '...
End plates 13 are applied to both ends of the row of
Pinch with. As shown in FIG. 4, a stepped through hole 14 is formed in the end plate 13 so as to penetrate the water passage 9 of the membrane module 4 ′, and the bolt 15 penetrated into the through hole 14.
And the nut 16 to tighten the laminated membrane modules 4 '... Since the end plate 13 is provided with a connection port 17 communicating with the through hole 14, the extraction pipe is connected to the connection port 17.

When a flat membrane laminated type membrane module as shown in FIG. 4 is immersed in raw water in an immersion tank to form a submerged membrane type separation device, a water passage interval 10 formed by interposing a gasket 11 is provided.
Raw water enters the inside, and the water of the raw water permeates the membrane 6 and enters the permeate flow channel 8. A drain pipe provided with a suction pump is connected to the downstream side of the extraction pipe. Therefore, the permeated water that has entered the permeated water channel 8 passes through the permeated water channel 8 due to the head difference and the suction action of the suction pump, is recovered from the water passage port 9 to the extraction pipe, and is drained from the drain pipe.

When such a membrane separation is performed, a cake layer is formed on the membrane surface or a gel-like substance adheres. When removing such an adhered substance, the cleaning liquid is pressure-fed from the take-out pipe side, A backwashing operation is performed in which the cleaning liquid is permeated from the inner surfaces of the membranes 6 and 6 to the outer surfaces, and the cake layers and the like attached to the outer surfaces of the membranes 6 and 6 are peeled off. Since the cleaning liquid permeates the membranes 6 and 6 in the direction opposite to the permeated water, the deposits such as cake layers are easily peeled off from the outer surfaces of the membranes 6 and 6 and removed.

Further, when this backwashing operation is performed, the pressure of the washing liquid in the direction of peeling from the permeate flow channel spacer 5 acts on the membrane 6, but the flat membranes 6 and 6 in this embodiment are only the outer peripheral portion by the thread 7. The inner side of the permeated water flow path spacer 5
Since it is sewn on and fixed to the membrane, the pressure of the washing solution is dispersed over the entire length of the linear suture fixing portion, which can prevent the flat membrane from being damaged.

In this embodiment, the outer peripheral edge of the membrane 6 and the inner side thereof are sewn with the thread 7, but the outer peripheral edge is sealed by a sealing means such as heat, adhesive bonding or high frequency welding as in the first embodiment. You may.

Another embodiment of the flat membrane laminated type membrane module 4 "shown in FIGS. 5 and 6 is one in which a plurality of membrane leaves 2'are attached to the central water collecting pipe 1 at predetermined intervals. The membrane leaf 2'of this embodiment, as shown in FIG.
Flat membranes 6 and 6 of the same shape and the same size are overlapped on both sides of a flat hexagonal net-shaped permeate flow path spacer 5, and the outer peripheral six sides are sewn with a thread 7, and the inside of this outer peripheral sewn portion is also The thread 7 is spirally sewn to form a spiral permeate flow channel 8 in the hexagonal membrane module 4 ″. The portion of the spiral permeate flow channel 8 that opens at the center is penetrated to the center. All communicate with the inside of the water collection pipe 1.

When the flat membrane laminated membrane module 4 "having such a structure is immersed in the raw water in the dipping tank, the raw water enters the water passage space formed between the adjacent membrane modules 4", Raw water passes through the membrane 6 and enters the permeate flow channel 8. An extraction pipe is connected to the water collection pipe 1, and a drain pipe provided with a suction pump is connected to the downstream side of the extraction pipe. Therefore, the permeated water that has entered the permeated water channel 8 passes through the spiral permeated water channel 8 due to the head difference and the suction action of the suction pump, and is collected in the central extraction pipe.
The water is collected from the water collection pipe 1 to the extraction pipe and drained from the drain pipe.

When such a membrane separation is carried out, a cake layer is formed on the surface of the membrane 6 or a gel-like substance is attached. When removing such an attached substance, as in the above-mentioned embodiment, A backwashing operation is performed in which the cleaning liquid is pressure-fed from the take-out pipe side, and the cleaning liquid is permeated from the inner surface to the outer surface of the membranes 6, 6 to peel off the cake layers and the like attached to the outer surfaces of the membranes 6, 6. Since the cleaning liquid permeates the membrane 6 in the direction opposite to the permeated water, the deposit such as the cake layer is easily peeled off from the outer surface of the membrane 6 and removed.

When the backwashing operation is performed, the pressure of the cleaning liquid in the direction of peeling from the permeate flow path spacer 5 acts on the membrane 6, but the flat membrane 6 in this embodiment is not limited to the outer peripheral portion by the thread 7. The inner side thereof is also sewn and fixed to the permeate flow path spacer 5 by a spiral sewn fixing portion. Therefore, the pressure of the cleaning solution is distributed over the entire length of the spiral suture fixing portion, and thus the flat membrane 6 can be prevented from being damaged.

In each of the above-mentioned embodiments, in order to carry out a backwash operation, a pipe for taking out permeated water and discharging it,
For example, a cleaning liquid pressure pump and an on-off valve are provided in the middle of the discharge pipe or the take-out pipe, and the cleaning liquid pressure pump is operated in a state where the flow passage is switched by the on-off valve to pump the cleaning liquid into the permeate flow passage 8 of the membrane module 4. This allows the cleaning liquid to permeate from the inner surface to the outer surface of the membrane 6.

[0029]

As described above, according to the present invention, since the permeate flow channel spacer and the membrane are fixed by the suturing means,
The reduction of the effective membrane area at the suture fixing portion can be suppressed to be extremely small, and the ratio of the effective membrane area that can be actually subjected to the membrane separation treatment can be increased. Therefore, efficient membrane separation treatment can be performed even with the same membrane area. Also, since the membrane can be firmly fixed at various positions by the suturing means,
The film is not damaged even if a backwashing operation is performed in which a water pressure acts in the direction of peeling the film, which enables efficient film cleaning, and is particularly effective for removing and removing the cake layer. Therefore, according to the present invention, it is possible to provide a membrane module capable of large-capacity treatment and capable of backwashing operation.

[Brief description of drawings]

FIG. 1 is a perspective view of a spiral wound type membrane module in a state in which a terminal portion of a membrane leaf is unwound and a part of a raw water flow path spacer is peeled off.

2 is an enlarged cross-sectional view of the membrane leaf shown in FIG.

FIG. 3 is a perspective view of a flat sheet membrane stack type membrane module.

FIG. 4 is an enlarged cross-sectional view of an end portion in a state where the membrane modules shown in FIG. 3 are stacked.

FIG. 5 is a front view of another embodiment of the flat sheet membrane-type membrane module.

6 is an XY cross-sectional view of the membrane module shown in FIG.

[Explanation of symbols]

 1 Water Collection Pipe 2 Membrane Leaf 3 Raw Water Flow Channel Spacer 4 Membrane Module 5 Permeate Flow Channel Spacer 6 Membrane 7 Thread 8 Permeate Flow Channel 9 Water Port 10 Water Passage 11 Gasket 13 End Plate 14 Through Hole 15 Bolt 17 Connection Port

Claims (1)

[Claims] 1. A membrane module for a membrane separation device, wherein sheet-like membranes are arranged on both sides with a permeate flow channel spacer interposed therebetween, and both membranes are fixed to the permeate flow channel spacer by a stitching means.