JPH11137974A - Spiral membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral membrane element capable of reducing the cost, easy in cleaning and high in reliability. SOLUTION: An individual or continuous envelope like membrane 3 is wound around the outer peripheral surface of a water collecting pipe, a raw water spacer 4 is inserted between the envelope like membranes 3 to form a spiral membrane component 1a. Slit like long pores extending in the axial direction are provided on the outer peripheral surface of the water collecting pipe 2. The outer peripheral surface of the spiral membrane component 1a is covered with an outer peripheral part flow passage material 5. The raw water is supplied at least from the outer peripheral part side of the spiral membrane element 1 and the permeated water is taken out from the opening end of the water collecting pipe 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral type membrane element used for a membrane separation device such as a low pressure reverse osmosis membrane separation device, an ultrafiltration device and a microfiltration device, and a method of operating the same.

[0002]

2. Description of the Related Art In recent years, a membrane separation technique has been applied to a water purification technique, and a membrane separation technique has been applied as a pretreatment of a reverse osmosis membrane separation system used for seawater desalination and the like.
As a type of membrane used for such membrane separation, a microfiltration membrane or an ultrafiltration membrane capable of obtaining a high amount of permeated water is widely used, but recently, an ultra-low pressure of 10 kgf / cm ² or less has been used. Reverse osmosis membranes that provide a permeate volume have also been developed.

As a form of the membrane element used for the membrane separation, a hollow fiber membrane element is often used in view of a membrane area per unit volume (volume efficiency). However, the hollow fiber membrane element has a disadvantage that the membrane is easily broken, and if the membrane is broken, the raw water mixes with the permeated water and the separation performance is reduced.

On the other hand, there is a spiral type membrane element as a form of a membrane element capable of increasing a membrane area. This spiral type membrane element has an advantage that separation performance can be maintained and reliability is high as compared with a hollow fiber membrane element.

FIG. 7 is a partially cutaway perspective view of a conventional spiral type membrane element, and FIG. 8 is a perspective view of a water collecting pipe used for the spiral type membrane element of FIG. FIG. 9 is an external perspective view of a conventional spiral type membrane element.

[0007] As shown in FIG. 7, the spiral membrane element 21 forms an envelope-like membrane (bag-like membrane) 23 by superimposing a separation membrane 26 on both surfaces of a permeated water spacer 25 and bonding three sides thereof. Then, the opening of the envelope-shaped membrane 23 is attached to the water collecting pipe 22 composed of a perforated hollow pipe, and the net-shaped (net-shaped)
The raw water spacer 24 is spirally wound around the outer peripheral surface of the water collecting pipe 22.

As shown in FIG. 8, a plurality of circular holes 22a are provided at regular intervals on the outer peripheral surface of the water collecting pipe 22 in order to maintain a certain strength.

The raw water spacer 24 is provided for forming a flow path through which raw water passes between the envelope-shaped membranes 23. If the thickness of the raw water spacer 24 is small, the filling efficiency of the separation membrane 26 is increased, but clogging with the suspended substance occurs. Therefore, usually, the thickness of the raw water spacer 24 is about 0.7 mm to 3.0 m.
m.

A spiral membrane element using a zigzag corrugated raw water spacer (so-called corrugated spacer) for treating raw water containing a large amount of suspended substances, such as river water, has already been known.

As shown in FIG. 9, the outer peripheral surface of the spiral type membrane element 21 is covered with an exterior material 27 made of FRP (fiber reinforced plastic), a shrinkable tube or the like.
Packing holders 28 called anti-telescopes are respectively attached to both ends.

FIG. 10 is a sectional view showing an example of a conventional method of operating a spiral type membrane element. As shown in FIG. 10, the pressure vessel (pressure-resistant vessel) 30 is constituted by a cylindrical case 31 and a pair of end plates 32a and 32b. A raw water inlet 33 is formed on one end plate 32a, and a concentrated water outlet 35 is formed on the other end plate 32b. A permeated water outlet 34 is provided at the center of the other end plate 32b.

A spiral type membrane element 21 having a packing 37 attached near one end of the outer peripheral surface is mounted in a cylindrical case 31, and both open ends of the cylindrical case 31 are sealed with end plates 32a and 32b, respectively. I do. One open end of the water collecting pipe 22 is fitted to the permeated water outlet 34 of the end plate 32b, and an end cap 36 is attached to the other open end.

During operation of the spiral membrane element 21, raw water 51 is introduced into the first liquid chamber 38 from the raw water inlet 33 of the pressure vessel 30. As shown in FIG.
Is supplied from one end face side of the spiral membrane element 21. The raw water 51 flows in the axial direction along the raw water spacer 24, and is discharged as concentrated water 53 from the other end surface side of the spiral membrane element 21. As the raw water 51 flows along the raw water spacer 24, the permeated water 52 that has passed through the separation membrane 26 is collected along the permeated water spacer 25 by the water collecting pipe 2.
2 and discharged from the end of the water collecting pipe 22.

The permeated water 52 is supplied to the pressure vessel 30 shown in FIG.
Is taken out from the permeated water outlet 34 to the outside. Further, the concentrated water 53 is taken out of the second liquid chamber 39 in the pressure vessel 30 through the concentrated water outlet 35 to the outside.

[0015]

When the membrane element is operated, the clogging of the membrane is caused by suspended substances in the raw water, and the permeation flux is reduced. For this reason, clogging is removed by performing chemical cleaning or the like to recover the permeation flux, but the labor and cost required for chemical cleaning poses a problem. Therefore, in order to prevent clogging, for example, in a hollow fiber membrane element,
Backwashing with permeate or air is performed periodically.

However, in the conventional spiral-type membrane element 21, since the outer peripheral surface of the envelope-like film 23 wound around the water collecting pipe 22 is covered with the exterior material 27, even if the backwashing is performed, the film of the membrane can be used. There is a problem that contaminants such as turbid substances causing clogging are easily captured by the raw water spacer 24 before being discharged from the end of the membrane element 21 and are not sufficiently removed.

Further, a gap existing between the inner peripheral surface of the cylindrical case 31 of the pressure vessel 30 of FIG. 10 and the spiral-type membrane element 21 becomes a dead space S, and stagnation of fluid (liquid pool) occurs. Spiral type membrane element 21
When used for a long period of time, the fluid staying in the dead space undergoes denaturation. In particular, when the fluid is a liquid containing an organic substance, germs such as microorganisms propagate, and the germs may decompose the organic substance to generate a bad smell or decompose the separation membrane. Leads to a decrease in

Further, in the conventional spiral type membrane element 21, raw water is supplied from one end of the spiral type membrane element 21 and discharged from the other end.
A packing holder 28 is required to prevent the envelope-shaped film 23 wound in 2 from being deformed into a bamboo shoot shape.
In addition, a pressure difference occurs between the raw water inflow side and the concentrated water outlet side due to the pressure loss due to the raw water spacer 24 and the pressure loss due to clogging, and the spiral membrane element 21 is deformed. In order to prevent this deformation, the outer peripheral surface of the envelope-like film 23 wound around the water collecting pipe 22 is covered with an exterior material 27 such as an FRP or a shrinkable tube. These increase component costs and manufacturing costs.

Further, it is necessary to obtain a sufficient film surface linear velocity in order to prevent the formation of cake due to contaminants in raw water, and for that purpose, a sufficient flow rate on the concentration side is required. If the flow rate on the concentration side is increased, the recovery rate per membrane element will be low, and the pump for supplying raw water will be large, and the system cost will be very large.

An object of the present invention is to provide a spiral-type membrane element which can be reduced in cost, is easy to clean, and has high reliability.

[0021]

Means for Solving the Problems and Effects of the Invention A spiral type membrane element according to a first aspect of the present invention has a plurality of independent or continuous outer peripheral surfaces of a perforated hollow tube having a slit-like elongated hole extending in an axial direction. A spiral membrane element is formed by winding the envelope membrane through a stock solution flow path material, and a stock solution is supplied from the outer peripheral side and both end sides of the spiral membrane element,
The permeate is discharged from at least one open end of the perforated hollow tube.

In the spiral membrane element according to the present invention, since the outer peripheral surface and both end surfaces of the spiral membrane element are open without being covered with the exterior material, the undiluted solution is supplied to the outer peripheral portion and both ends of the membrane element. Supply from the department side,
Full volume filtration can be performed. This increases the permeation flux per unit membrane area.

In this case, since the perforated hollow tube is provided with a slit-like elongated hole extending in the axial direction, the resistance when the permeated liquid permeating the envelope-like membrane flows into the perforated hollow tube is reduced. Become smaller. Therefore, the efficiency of the membrane element is increased, and the initial transmembrane pressure difference can be reduced.

As described above, since the stock solution is supplied from the outer peripheral side and both ends of the membrane element, contaminants are trapped at the outer peripheral side and both ends of the membrane element. Therefore, it is possible to uniformly remove contaminants by backwashing with a washing liquid such as permeated water.

When the cleaning liquid is introduced from at least one open end of the perforated hollow tube during backwashing, the cleaning liquid derived from the slit-shaped long hole of the perforated hollow tube passes through the envelope-shaped membrane and is undiluted. It flows along the flow path material and is discharged from the outer peripheral portion and both ends of the spiral membrane element. Thereby,
Contaminants trapped on the outer periphery and both ends of the membrane element are separated from the membrane element and discharged out of the system together with the cleaning liquid. Therefore, the contaminants trapped on the outer periphery and both ends of the membrane element can be uniformly removed.

In this case, the washing liquid introduced into the perforated hollow tube is evenly distributed over the entire area of the separation membrane through the slit-like elongated holes extending in the axial direction, so that the backflow washing is effectively performed. Therefore, clogging of the separation membrane is prevented,
Long-term stable operation is performed.

Further, according to the structure of the present invention, dead space is not formed in the gap between the membrane element and the pressure vessel due to the total filtration, so that the fluid remains in the gap between the membrane element and the pressure vessel. Does not occur. Therefore, even when used to separate fluids containing organic matter,
Problems such as propagation of various bacteria such as microorganisms, generation of offensive odor due to decomposition of organic matter, and decomposition of the separation membrane do not occur, and high reliability can be obtained.

Further, a stock solution is supplied from the outer peripheral side and both ends of the membrane element, and pressure is applied to the membrane element from all directions, and no pressure that causes displacement in the axial direction is applied. The envelope-shaped membrane wound around the tube does not deform into a bamboo shoot. This eliminates the need for a packing holder and an exterior material, thereby reducing parts costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, the system cost is reduced.

Since pressure is applied to the membrane element from all directions, the membrane element does not deform even if the supply pressure of the stock solution is increased. Therefore, high pressure resistance can be obtained.

In the spiral type membrane element according to the second invention, a plurality of envelope-like membranes, which are independent or continuous on the outer peripheral surface of a perforated hollow tube having a slit-like elongated hole extending in the axial direction, form a raw liquid flow path material. The spiral membrane element is formed by being wound around the spiral membrane element, one end of the spiral membrane element is sealed, and the undiluted solution is supplied from the outer peripheral side and the other end side of the spiral membrane element. The permeated liquid is led out from at least one of the open ends.

In the spiral type membrane element according to the present invention, since the outer peripheral surface and one end surface of the spiral membrane element are open without being covered with the exterior material, the undiluted solution is supplied to the outer peripheral side and one end of the membrane element. Supply from the department side,
Full volume filtration can be performed. This increases the permeation flux per unit membrane area.

In this case, since the slit-shaped long hole extending in the axial direction is provided in the perforated hollow tube, the resistance when the permeated liquid permeating the envelope-like membrane flows into the perforated hollow tube is reduced. Become smaller. Therefore, the efficiency of the membrane element is increased, and the initial transmembrane pressure difference can be reduced.

As described above, since the stock solution is supplied from the outer peripheral portion and one end portion of the membrane element, contaminants are trapped at the outer peripheral portion and one end portion of the membrane element. Therefore, it is possible to uniformly remove contaminants by backwashing with a washing liquid such as permeated water.

When the cleaning liquid is introduced from at least one open end of the perforated hollow tube at the time of backwashing, the cleaning liquid derived from the slit-shaped long hole of the perforated hollow tube passes through the envelope-shaped membrane and is undiluted. It flows along the flow path material and is discharged from the outer periphery and one end of the spiral membrane element. Thereby,
The contaminants trapped on the outer periphery and one end of the membrane element are separated from the membrane element and discharged out of the system together with the cleaning liquid. Therefore, the contaminants trapped on the outer periphery and one end of the membrane element can be uniformly removed.

In this case, the washing liquid introduced into the perforated hollow tube is evenly distributed over the entire area of the separation membrane through the slit-like elongated holes extending in the axial direction, so that the backwashing is effectively performed. Therefore, clogging of the separation membrane is prevented,
Long-term stable operation is performed.

In particular, since a space for supplying the undiluted solution is not required on the sealed end side of the membrane element, the pressure vessel for accommodating the membrane element can be downsized. Further, by disposing the sealed end of the membrane element on the side of the undiluted solution inlet of the pressure vessel, it is possible to prevent dirt from being attached to the end face of the spiral membrane element due to the dynamic pressure of the undiluted solution during undiluted solution introduction. it can.

Also, in the structure of the present invention, dead space is not formed in the space between the membrane element and the pressure vessel by the whole amount filtration, so that propagation of various bacteria such as microorganisms can be prevented.
There is no problem such as generation of offensive odor and decomposition of the separation membrane due to decomposition of organic substances, and high reliability can be obtained.

Further, since pressure is applied from all directions of the membrane element and does not apply a pressure that causes displacement in the axial direction, the envelope-shaped membrane wound around the perforated hollow tube is deformed into a bamboo shoot. There is no. This eliminates the need for a packing holder and an exterior material, thereby reducing parts costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, the system cost is reduced.

Since pressure is applied to the membrane element from all directions, the membrane element does not deform even if the supply pressure of the stock solution is increased. Therefore, high pressure resistance can be obtained.

The spiral membrane element according to the third invention is characterized in that a plurality of envelope-like membranes, which are independent or continuous on the outer peripheral surface of a perforated hollow tube having a slit-like elongated hole extending in the axial direction, form a stock solution flow path material. A spiral membrane element is formed by winding the spiral membrane element, both ends of the spiral membrane element are sealed, and a stock solution is supplied from the outer peripheral side of the spiral membrane element, and at least one opening of the perforated hollow tube is provided. The permeate is discharged from the end.

In the spiral membrane element according to the present invention, since the outer peripheral surface of the spiral membrane element is open without being covered with the exterior material, the undiluted solution is supplied from the outer peripheral side of the membrane element. Filtration can be performed. This increases the permeation flux per unit membrane area.

In this case, since the perforated hollow tube is provided with a slit-like elongated hole extending in the axial direction, the resistance when the permeated liquid permeating the envelope-like membrane flows into the perforated hollow tube is reduced. Become smaller. Therefore, the efficiency of the membrane element is increased, and the initial transmembrane pressure difference can be reduced.

As described above, since the stock solution is supplied from the outer peripheral side of the membrane element, contaminants are trapped at the outer peripheral section of the membrane element. Therefore, it is possible to uniformly remove contaminants by backwashing with a washing liquid such as permeated water.

When the cleaning liquid is introduced from at least one open end of the perforated hollow tube during backwashing, the cleaning liquid derived from the slit-shaped long hole of the perforated hollow tube passes through the envelope-shaped membrane and is undiluted. It flows along the flow path material and is discharged from the outer peripheral portion of the spiral membrane element. As a result, the contaminants trapped on the outer periphery of the membrane element are separated from the membrane element and discharged out of the system together with the cleaning liquid. Therefore, the contaminants trapped on the outer periphery of the membrane element can be uniformly removed.

In this case, the cleaning liquid introduced into the perforated hollow tube is evenly distributed over the entire area of the separation membrane through the slit-like elongated holes extending in the axial direction, so that the backflow cleaning is performed effectively. Therefore, clogging of the separation membrane is prevented,
Long-term stable operation is performed.

In particular, since there is no need to provide a space for supplying the undiluted solution to the sealed both ends of the membrane element, the pressure vessel for housing the membrane element can be downsized. Further, by disposing one of the sealed both ends of the membrane element on the side of the undiluted liquid inlet of the pressure vessel, it is possible to prevent dirt from adhering to the end face of the spiral membrane element due to the dynamic pressure of the undiluted liquid when introducing undiluted liquid. be able to.

Also, in the structure of the present invention, dead space is not formed in the space between the membrane element and the pressure vessel by the total filtration, so that the propagation of various bacteria such as microorganisms can be prevented.
There is no problem such as generation of offensive odor and decomposition of the separation membrane due to decomposition of organic substances, and high reliability can be obtained.

Further, since pressure is applied from all directions of the membrane element and no pressure causing displacement in the axial direction is applied, the envelope-shaped membrane wound around the perforated hollow tube is deformed into a bamboo shoot. There is no. This eliminates the need for a packing holder and an exterior material, thereby reducing component costs and manufacturing costs. In addition, since the whole amount is filtered, a high recovery rate can be obtained without using a large pump for supplying the stock solution. Thereby, the system cost is reduced.

Since pressure is applied to the membrane element from all directions, the membrane element does not deform even if the supply pressure of the stock solution is increased. Therefore, high pressure resistance can be obtained.

[0050] In the spiral membrane element according to the first, second or third invention, the width of the slit-like long hole of the perforated hollow tube is preferably 2 mm or more and 6 mm or less. Thereby, the resistance when the permeated liquid flows into the perforated hollow tube can be reduced while maintaining sufficient strength.

In the spiral membrane element according to the first, second or third aspect, the perforated hollow tube is
It is preferably made of metal, fiber reinforced plastic, plastic or ceramic. Thereby, sufficient strength can be obtained.

[0052]

FIG. 1 is a partially cutaway perspective view of a spiral membrane element according to an embodiment of the present invention.
FIG. 2 is a perspective view of a water collecting pipe used in the spiral membrane element of FIG. FIG. 3 is a cross-sectional view showing an example of an envelope-shaped membrane of the spiral membrane element of FIG.
FIG. 4 is a cross-sectional view showing another example of the envelope-shaped membrane of the spiral membrane element of FIG.

The spiral type membrane element 1 shown in FIG.
Includes a spiral-shaped membrane element 1a formed by winding a plurality of independent envelope-shaped membranes 3 or a plurality of continuous envelope-shaped membranes 3 on the outer peripheral surface of a water collecting pipe 2 composed of a perforated hollow pipe. . A raw water spacer (raw liquid flow path material) 4 is inserted between the envelope films 3 in order to prevent the envelope films 3 from adhering to each other and to reduce the film area, and to form a flow path for raw water. Have been. Spiral membrane element 1
The outer peripheral surface of a is covered with an outer peripheral channel material 5 made of a net formed of plastic, metal, rubber, fiber, or the like such as polypropylene, polyethylene, or polystyrene.

As shown in FIG. 2, a slit-shaped long hole 2a extending in the axial direction is provided on the outer peripheral surface of the cylindrical water collecting pipe 2. In the present embodiment, as shown in FIGS. 3 and 4, four long holes 2 a are provided in the water collecting pipe 2. The water collecting pipe 2 is formed of a material having relatively high strength such as metal, FRP (fiber reinforced plastic), plastic, and ceramics.

When the width W of each long hole 2a is smaller than 2 mm, the resistance of the permeated water permeating the envelope membrane 3 when flowing into the water collecting pipe 2 increases. On the other hand, the width W of each slot 2a
Is larger than 6 mm, sufficient strength cannot be obtained. Therefore, the width W of each long hole 2a is 2 mm or more and 6 mm.
The following is preferred.

As shown in FIG. 3 and FIG.
Is formed by superposing two separation membranes 7 on both sides of a permeated water spacer (permeated liquid flow path material) 6 and bonding three sides thereof, and the opening of the envelope-shaped membrane 3 is formed on the outer periphery of the water collecting pipe 2. Attached to the surface. 10 kgf / c for the separation membrane 7
Low pressure reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, etc., operated at m ² or less are used.

In the example of FIG. 3, a plurality of envelope-shaped membranes 3 are formed by independent separation membranes 7, respectively. In the example of FIG.
A plurality of envelope membranes 3 are formed by folding a continuous separation membrane 7.

If the thickness of the raw water spacer 4 is larger than 0.5 mm, it becomes difficult to capture contaminants in the raw water at least at the outer peripheral portion of the membrane element 1. On the other hand, raw water spacer 4
If the thickness is smaller than 0.1 mm, the envelope-shaped films 3 are easily brought into contact with each other, and the film area is reduced. Therefore, the thickness of the raw water spacer 4 is 0.1 mm or more and 0.5 mm or more.
The following is preferred.

When the thickness of the outer peripheral channel member 5 is larger than 30 mm, the volume efficiency of the membrane element 1 with respect to the pressure vessel storing the membrane element 1 is reduced. On the other hand, if the thickness of the outer peripheral channel member 5 is smaller than 0.6 mm, the flow rate of the raw water for discharging contaminants attached to at least the outer peripheral portion of the membrane element 1 during backflow cleaning of the permeated water is small. Become. Therefore, the thickness of the outer peripheral portion flow path member 5 is set to 0.
It is preferably from 6 mm to 30 mm.

FIG. 5 is a sectional view showing an example of an operation method of the spiral membrane element of the present embodiment. As shown in FIG. 5, the pressure vessel (pressure-resistant vessel) 10 includes a cylindrical case 11 and a pair of end plates 12a and 12b. A raw water inlet 13 is formed on one end plate 12a, and a raw water outlet 15 is formed on the other end plate 12b. A permeated water outlet 14 is provided at the center of the other end plate 12b.

The spiral membrane element 1 is housed in a cylindrical case 11, and both open ends of the cylindrical case 11 are sealed by end plates 12a and 12b, respectively. One end of the water collecting pipe 2 is fitted to the permeated water outlet 14 of the end plate 12b, and an end cap 16 is attached to the other end. End plate 1
A pipe 17 and a valve 18 are connected to the raw water outlet 15 of 2b.

During the operation of the spiral membrane element 1, the raw water 51 is introduced into the pressure vessel 10 from the raw water inlet 13 of the pressure vessel 10. The raw water 51 is supplied from at least the outer peripheral side of the spiral membrane element 1 to the raw water spacer 4.
Along the space between the envelope-shaped membranes 3. In the example of FIG. 4, raw water 51 enters between the envelope-shaped membranes 3 from the outer peripheral side and both end sides of the spiral membrane element 1. The permeated water that has passed through the separation membrane 7 flows into the water collecting pipe 2 along the permeated water spacer 6. Thereby, the permeated water outlet 14 of the pressure vessel 10
The permeated water 52 is taken out from the tank. In this way, total filtration is performed.

In this case, the thickness of the raw water spacer 4 is so small that contaminants such as turbid substances are captured at least at the outer peripheral portion (the outer peripheral portion and both ends in the example of FIG. 5) of the membrane element 1. A cake layer is formed by a contaminant on at least the outer peripheral portion of the device. At least the outer periphery of the membrane element is subjected to cake filtration by the cake layer, and the inside of the membrane element 1 is subjected to membrane filtration by the separation membrane 7.

The raw water may be partially extracted from the raw water outlet 15 by opening the valve 18. In this case, a flow of raw water can be formed at the outer peripheral portion of the membrane element 1. Thereby, a part of the contaminants can be discharged to the outside of the pressure vessel 10 while the sedimentation of the contaminants in the raw water is suppressed.

After filtration for a certain period of time, backwashing with permeated water is performed from the permeation side. The permeated water at the time of backwashing flows from the water collecting pipe 2 along the raw water spacer 4 toward at least the outer peripheral portion. Thereby, the contaminants captured at least at the outer peripheral portion of the membrane element 1 are easily peeled off. At this time, when the valve 18 is opened while supplying the raw water from the raw water inlet 13, the separated contaminants are discharged out of the system. As a result, the membrane flux is remarkably recovered compared to before the backwashing.

In the spiral type membrane element 1 of this embodiment, since the water collecting pipe 2 is provided with the slit-like long hole 2a extending in the axial direction, the permeated water transmitted through the envelope-shaped membrane 3 is supplied to the water collecting pipe 2. The resistance when flowing into the interior is reduced.
Thereby, the efficiency of the membrane element 1 is increased, and the initial transmembrane pressure difference can be reduced.

Further, at the time of backwashing, the permeated water introduced into the inside of the water collecting pipe 2 is provided with a slit-shaped long hole 2a extending in the axial direction.
To the entire area of the separation membrane 7, so that backwashing is effectively performed. Therefore, clogging of the separation membrane 7 is prevented, and stable operation is performed for a long period of time.

Further, in the spiral type membrane element 1 of the present embodiment, no dead space is formed in the space between the membrane element 1 and the pressure vessel 10 by the above-mentioned filtration mode, so that germs such as microorganisms can be removed. High reliability can be obtained without problems such as propagation, generation of offensive odor due to decomposition of organic matter, and decomposition of separation membrane.

Further, since pressure is applied to the membrane element 1 from all directions, there is no problem of deformation of the membrane element 1 and the packing holder and the exterior material are not required. Thereby,
Component and manufacturing costs are reduced.

Further, since the whole amount is filtered, it is not necessary to use a large pump for supplying raw water. Thereby, the system cost is reduced.

FIG. 6 is a front view of a spiral membrane element according to another embodiment of the present invention. In FIG. 6, the illustration of the outer peripheral channel material is omitted.

The spiral type membrane element 1 shown in FIG.
In, both end portions of the spiral membrane element 1a are sealed with a resin layer 19. In the spiral membrane element 1 shown in FIG. 6B, one end of the spiral membrane element 1 a is sealed with a resin layer 19.

In the spiral type membrane element 1 shown in FIGS. 5A and 5B, the number of working steps in manufacturing increases, but a space for supplying raw water to both ends or one end of the membrane element 1 becomes unnecessary. Therefore, the pressure vessel can be reduced in size, and the spiral membrane module in which the membrane element 1 is housed in the pressure vessel can be reduced in size.

Further, by arranging the end portion of the membrane element 1 sealed with the resin layer 19 on the side of the raw water inlet of the pressure vessel, the dirt adheres to the end face of the membrane element 1 due to the dynamic pressure of the raw water when the raw water is introduced. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a spiral membrane element according to an embodiment of the present invention.

FIG. 2 is a perspective view of a water collecting pipe used in the spiral membrane element of FIG.

FIG. 3 is a cross-sectional view showing an example of an envelope-shaped membrane of the spiral membrane element shown in FIG.

4 is a cross-sectional view showing another example of the envelope-shaped membrane of the spiral-wound membrane element of FIG.

FIG. 5 is a cross-sectional view showing an example of an operation method of the spiral membrane element of FIG.

FIG. 6 is a front view of a spiral-type membrane element according to another embodiment of the present invention.

FIG. 7 is a partially cutaway perspective view of a conventional spiral-type membrane element.

FIG. 8 is a perspective view of a water collecting pipe used in the spiral membrane element of FIG. 7;

FIG. 9 is an external perspective view of a conventional spiral-type membrane element.

FIG. 10 is a cross-sectional view illustrating an example of a conventional method of operating a spiral-type membrane element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spiral type membrane element 1a Spiral type membrane element 2 Water collecting pipe 2a Slot 3 Envelope type membrane 4 Raw water spacer 5 Peripheral channel material 6 Permeated water spacer 7 Separation membrane 10 Pressure vessel 13 Raw water inlet 14 Permeated water outlet 51 Raw water 52 Permeation water

Claims (5)

[Claims] 1. A plurality of independent or continuous envelope membranes are wound around an outer peripheral surface of a perforated hollow tube having a slit-like long hole extending in an axial direction via a stock solution flow path material to form a spiral membrane element. Is formed, an undiluted solution is supplied from the outer peripheral side and both ends of the spiral membrane element, and a permeate is drawn out from at least one open end of the perforated hollow tube. element. 2. A spiral membrane element in which a plurality of independent or continuous envelope membranes are wound around the outer peripheral surface of a perforated hollow tube having a slit-like elongated hole extending in the axial direction via a stock solution flow path material. Is formed, one end of the spiral membrane element is sealed, and the undiluted solution is supplied from the outer peripheral side and the other end side of the spiral membrane element, and from at least one open end of the perforated hollow tube. A spiral-type membrane element from which a permeate is discharged. 3. A spiral membrane element in which a plurality of independent or continuous envelope membranes are wound around the outer peripheral surface of a perforated hollow tube having a slit-like elongated hole extending in the axial direction via a stock solution flow path material. Is formed, both ends of the spiral membrane element are sealed, a stock solution is supplied from the outer peripheral side of the spiral membrane element, and a permeate is derived from at least one open end of the perforated hollow tube. A spiral type membrane element characterized by the following. 4. The spiral membrane element according to claim 1, wherein the width of the slit-shaped long hole of the perforated hollow tube is 2 mm or more and 6 mm or less. 5. The spiral-type membrane element according to claim 1, wherein the perforated hollow tube is made of metal, fiber reinforced plastic, plastic or ceramic.