JPH11169684A - Method of backwashing spiral membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively backwash a spiral membrane module in which a water collecting pipe is eliminated and permeated water flow resistance is lessened. SOLUTION: In a bag like membrane 10 whose side parts 11, 12, 13 are closed and a part of whose side part 14 is open, a flow passage material 15 is inserted, and to the bag like membrane 10, adhesives 16, 17 and 18 are adhered. The bag like membrane 10 is wound around a shaft 20. To the end face of the wound bag like membrane 10, a socket is fitted, and the outer periphery side thereof is made a permeated water outflow port and the inside thereof is made a concentrated water outflow port. This spiral membrane module is housed in a vessel. On backwashing, gas is fed to a gas line to make permeated water flow backward and perform backwashing with water, and then, the gas is fed to perform backwashing with a gas-liquid mixture and backwashing with gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a membrane module used in a membrane separation apparatus, there is a spiral type membrane module in which a separation membrane is wound around a water collecting pipe.

FIG. 6 is a partially exploded perspective view showing the structure of a conventional spiral type membrane module.

A plurality of bag-shaped separation membranes 2 are wound around the outer periphery of a water collecting pipe 1 via a mesh spacer 3.

[0005] The water collecting pipe 1 is provided with a slit-shaped opening communicating with the inside and outside of the pipe. The separation membrane 2 has a bag shape,
The central part surrounds the water collection pipe 1. A channel material 4 made of a mesh spacer or the like is inserted inside the bag-shaped separation membrane 2, and the inside of the bag-shaped separation membrane (bag-shaped membrane) 2 is a permeated water channel.

[0006] A top ring 6 and an end ring 7 are provided at both ends of a wound body 5 of the bag-shaped membrane 2, and a brine seal 8 is provided around the outer periphery thereof.

The raw water flows into the raw water flow path between the bag-like membranes 2 from the front end face of the wound body 5, flows in the longitudinal direction of the wound body 5 as it is, and concentrates from the rear end face of the wound body 5. Leaked as. While flowing through the raw water flow path, water permeates the bag-like membrane 2 and enters the inside thereof, flows into the water collecting pipe 1, and is taken out of the module from the rear end side of the water collecting pipe 1.

[0008]

The above-mentioned conventional spiral type membrane module has the following problems to be solved.

In order to increase the flow rate of the permeated water in the water collecting pipe 1, it is necessary to increase the diameter of the water collecting pipe 1, but in such a case, the diameter of the spiral membrane module becomes large. The permeated water that has permeated into the bag-shaped membrane 2 flows to the water collecting pipe 1 while spirally flowing through the bag-shaped membrane 2.
The flow resistance in the bag-like membrane 2 is large. Moreover, the flow resistance near the slit portion of the water collecting pipe flowing into the water collecting pipe 1 from the inside of the bag-shaped membrane 2 is large. The flow rate of the raw water flowing through the raw water flow path decreases toward the downstream side. (The flow rate of raw water decreases as much as the raw water is concentrated.)
For this reason, the raw water flow velocity is low in the downstream of the raw water flow path,
Dirt easily adheres.

The present inventor has solved the above conventional problems,
A water collecting pipe is unnecessary, and as a spiral membrane module having a small permeated water flow resistance, a bag-like membrane is wound around a shaft to form a wound body. Raw water is supplied from one end surface of the wound body, and the permeated water is wound. Japanese Patent Application No. 9-82780 proposes a spiral-type membrane module that can be taken out from the other end surface of the rotator. An object of the present invention is to provide a method for efficiently backwashing such a spiral-wound membrane module without a water collecting pipe.

[0011]

According to the method for backwashing a spiral type membrane module of the present invention, a permeated water flow path material is disposed inside a bag-like membrane, and a raw water flow path material is disposed between the bag-like membranes. In the method of backwashing spiral type membrane module,
The spiral-type membrane module is configured such that a bag-like membrane is wound around a shaft to form a wound body, raw water is supplied from one end surface of the wound body, and permeated water is taken out from the other end surface of the wound body. At the time of backwashing, a backwash gas is supplied to the permeated water side in a state where there is permeated water inside the wound body, and the remaining permeated water is backflowed. It is characterized in that the gas supply is continued until only the gas flows after passing through.

[0012] In this backwashing method, the residual permeated water in the bag-like membrane flows back under gas pressure to perform water backwashing.
Backwashing is performed in a gas-liquid mixed state with the amount of residual permeated water reduced. Then, when the residual permeated water is exhausted, only the gas flows back and gas backwashing is performed. By continuously performing the water backwashing, the gas-liquid mixing backwashing, and the gas backwashing, the backwashing is sufficiently performed and the permeated water amount is sufficiently recovered.

[0013] The spiral membrane module of the present invention is a spiral membrane module in which a permeated water flow path material is disposed inside a bag-like membrane, and a raw water flow path material is disposed between the bag-like membranes. The bag-like membrane has a substantially rectangular shape having first, second, third and fourth sides, the first, second and third sides are sealed, and the fourth side is one side. The part is an open part and the remaining part is a closed part, and the first part is orthogonal to the fourth side.
The side of is wound on the shaft to form a wound body by winding the bag-like membrane, the fourth side faces the rear end face of the wound body, and the second side facing the fourth side. With the side facing the front end face of the wound body, the raw water flow path between the bag-like membranes is entirely sealed in the third side, and in the fourth side, It is preferable that a portion overlapping with the open portion of the bag-shaped membrane is a closed portion, and a portion overlapping with the closed portion of the bag-shaped film is an open portion.

In this spiral type membrane module, raw water flows into the raw water flow path from the front end face of the wound body. The raw water flows through the raw water flow path in a direction substantially parallel to the axis of the wound body, and then flows out as concentrated water from the raw water flow path opening at the rear end face of the wound body.

The water that has passed through the bag-like membrane flows in the bag-like membrane in a direction substantially parallel to the axis of the wound body, and flows out of the bag-shaped membrane opening at the rear end face of the wound body.

As described above, since the permeated water flows in the bag-like membrane in a direction parallel to the axis of the wound body, the water collecting pipe used in the conventional spiral membrane module becomes unnecessary. Then, there is no flow resistance when flowing into the water collecting pipe from inside the bag-shaped membrane, and the flow resistance of permeated water is reduced.

Since the water collecting pipe is eliminated, the length of the bag-shaped membrane in the winding direction can be increased accordingly.
The membrane area can be expanded. And even if the length in the winding direction of the bag-like membrane is increased, the flow resistance of the permeated water does not increase,
The amount of permeated water can be increased.

Further, since the raw water flow path is opened only at a part of the rear end face of the wound body, the flow rate of the raw water (concentrated water) downstream of the raw water flow path can be increased as compared with the conventional case. In addition, the adhesion of dirt in the downstream area of the raw water flow path can be prevented.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of a bag-like membrane of a spiral membrane module to which a backwash method according to an embodiment of the present invention is applied and a shaft around which the bag-like membrane is wound. FIGS. 1B and 1C respectively show FIG.
It is sectional drawing which follows the BB line and CC line of FIG. FIG. 2 is a sectional view showing a method of winding a bag-like membrane around a shaft, FIG. 3 is a perspective view showing an engagement relationship between a wound body and a socket, and FIG.
FIG. 2 is a side view of the spiral membrane module. FIG. 5 is a system diagram showing a method for back washing the spiral membrane module.

The bag-like film 10 has a square or rectangular shape and includes a first side 11, a second side 12, a third side 13, and a fourth side 14. I have. This bag-shaped membrane 10 is formed by folding one long separation membrane film into two at the second side portion 12 and separating the separation membrane films folded at the first side portion 11 and the third side portion 13 from each other. The fourth side portion 14 is formed in a bag shape with an open portion without being bonded by an adhesive or the like.

From the middle of the fourth side 14 to the third side 13
The separation membrane films of the bag-like membrane 10 are not adhered to each other, and the opening portion 30 for permeated water outflow is formed. Further, from the middle of the fourth side portion 14 to the first side portion 11, the separation membrane films of the bag-like membrane 10 are adhered to each other, forming a closing portion 31 for preventing outflow of permeated water. I have.

A permeated water flow path material (for example, a mesh spacer) 15 is inserted and arranged in the bag-like membrane 10. Note that the bag-shaped membrane 10 is not limited to a single long film folded in two at the second side 12, and two separation membrane films are overlapped to form the first side 1.
1, second side 12, third side 13, and fourth side 1
4 may be bonded.

On one surface of the bag-like film 10, an adhesive 1
6 is adhered and adhesives 17 and 18 are adhered to the other surface, and the bag-like film 10 is wound around the shaft 20. The adhesive 16 is applied along the first side 11, and the adhesive 17 is applied along the third side 13. The adhesive 18 is applied along the opening 30 for outflow of permeated water from the intermediate portion in the longitudinal direction of the fourth side portion 14 to the third side portion 13.

By winding a plurality of bag-shaped membranes 10 around the shaft 20, the overlapping bag-shaped membranes 10 are joined in a water-tight manner at the adhesives 17 and 18. Thus, a raw water flow path through which raw water (and concentrated water) flows is formed between the bag-like membranes 10, 10,.... As the adhesive 18 cures, an open portion for flowing out the raw water (concentrated water) is formed on the rear end surface of the wound body on the inner peripheral side, and a closing portion for preventing raw water outflow is formed on the outer peripheral side. You.

Fins 19 extend from the boundary between the open portion 30 for permeate outflow and the closed portion 31 for permeate outflow prevention in the fourth side portion 14 toward the rear of the wound body. I have. The fins 19 are made of, for example, a synthetic resin film or sheet, and are preferably bonded to the bag-like film 10 by adhesion or the like.

Are wound around the shaft 20 via a raw water flow path material (mesh spacer) 29 as shown in FIG. 2 to form a wound body 24 as shown in FIG. You. The fin 19 extends from the rear end face of the wound body 24. By providing fins 19 at the same location on the fourth side 14 of each bag-like membrane 10,
The fins 19 are located at an equiradius from the axis of the wound body 24, and the fins 19 form a ring-shaped projection by overlapping the fins 19. The rear end of the cylindrical socket 25 is inserted into the ring-shaped protrusion, and the socket 25 and the fin 19 are joined with an adhesive or the like. Note that the socket 25 may be externally fitted to the fin 19. Further, a cutting groove may be formed on the rear end face of the wound body 24 along the fins 19 with a lathe, and the end of the socket 25 may be embedded in the groove.

By joining the socket 25 and the fins 19 in this manner, a permeated water outflow region on the outer peripheral side of the rear end face of the wound body 24 and a concentrated water outflow region on the inner peripheral side of the socket 25 are defined. .

When the bag-like film 10 is wound around the shaft 20, as shown in FIG.
A raw water flow path material (mesh spacer) 29 is interposed between them. The raw water flow path is formed by interposing these mesh spacers 29.

As shown in FIG. 4, a top ring 26 and an end ring 27 are provided at the leading edge and the trailing edge of the wound body 24, respectively.
Is formed by a synthetic resin mold or the like, and the top ring 26 is formed.
A brine seal 28 is provided around the outer periphery of.

In the spiral type membrane module configured as described above, as shown in FIG. 4, raw water flows into the raw water flow path between the bag-like membranes 10, 10,. I do. This raw water flows through the raw water flow path in a direction substantially parallel to the axis of the wound body 24, and is taken out from the end face inside the socket 25 at the rear end of the wound body 24. Then, while the raw water flows through the raw water flow path, the water permeates into the bag-like membrane 10, and the permeated water flows through the socket 25 on the rear end face of the wound body 24.
Flows out from the outer periphery of the.

In this spiral type membrane module, the permeated water flows in the bag-like membrane 10 in a direction parallel to the axis of the wound body 24 and is taken out from the rear end face. The used collecting pipe is unnecessary. For this reason, the flow resistance when flowing from the bag-like membrane into the water collecting pipe is eliminated, and the permeated water flow resistance is significantly reduced.

Since the water collecting pipe is omitted, the length of the bag-like membrane 10 in the winding direction can be increased by that much.
It is possible to increase the film area. Even if the length of the bag-like membrane in the winding direction is increased, the permeated water flow resistance does not increase,
The amount of permeated water can be increased.

In this spiral type membrane module, the outlet portion of the raw water flow path is provided only inside the socket 25, and the outlet (the most downstream portion) of the raw water flow path is narrowed. The flow rate of the raw water (concentrated water) becomes sufficiently large also on the downstream side of the road, and the adhesion of dirt in the downstream area of the raw water flow path can be prevented. The area inside and outside the socket 25 (the length of the adhesive 18 in the side portion 14 direction) is preferably determined according to the water recovery rate of the spiral membrane module.

In this spiral type membrane module, the socket 25 is connected to the wound body 24 using the fins 19.
And the connection strength between the socket 25 and the winding body 24 is high. Then, the inflow side of the raw water and the outflow side of the concentrated water are partitioned in a watertight manner by the socket 25.

Next, a method for backwashing the spiral membrane module will be described with reference to FIG. The spiral membrane module 40 is housed in a cylindrical pressure-resistant vessel 50. Raw water port 5 at the front end of vessel 50
1 is connected to a raw water line 60 having a valve 61. Raw water line 6 between this valve 61 and raw water port 51
From 0, the backwash drainage line 62 branches, and the drainage line 62 is provided with a valve 63.

The socket 25 is fitted in the concentrated water port 52 at the center of the rear end surface of the vessel 50. The concentrated water port 52 is connected to a concentrated water line 70 having a valve 71. A gas vent line 72 branches off from the concentrated water line 70, and the gas vent line 72 is provided with a valve 73.

A permeated water line 53 having a valve 81 is connected to a permeated water port 53 located on the peripheral side of the rear end face of the vessel 50.
Is connected. A gas vent line 82 having a valve 83 is branched from between the valve 81 of the permeate line 80 and the permeate port 53. A gas line 84 for backwashing is connected to a permeated water line 80 between the valve 81 and the permeated water port 53, and a valve 85 is provided in the gas line 84.

(A) As shown in the figure, during the water flow operation (membrane separation processing operation), the valves 61, 71, 81 are opened and the other valves 63, 73, 83, 85 are closed. And
Raw water is supplied from the raw water port 51 into the vessel 50,
The concentrated water is supplied from socket 25, port 52 and concentrated water line 7.
0, and the permeate flows from the permeate chamber 54 on the rear side in the vessel 50 to the permeate port 53 and the permeate line 8.
Retrieved via 0.

(B) When performing backwashing as shown in the figure, the valves 61, 71, 81, 73 and 83 are opened and the valves 63 and 85 are opened.
Is closed. Then, the gas is supplied to the gas line 84. Thereby, the backflow water pressure propagates through the permeated water port 53 and the permeated water chamber 54 in the vessel 50 to the permeated water flow path in the bag-shaped membrane 10 of the spiral type membrane module 40, and the permeated water chamber 54 and the bag-shaped membrane 10 The remaining permeated water flows into the raw water flow path between the bag-like membranes 10 and flows out through the raw water port 51 and the backwash drainage extraction line 62. When the gas supply to the gas line 84 is continued (the gas is supplied continuously or intermittently), the amount of the remaining permeated water is reduced, and the permeated water and the gas flow backward in a gas-liquid mixed state, and the gas-liquid mixing Backwashing is performed. When the residual permeated water substantially disappears, only the gas flows backward, and only the gas is discharged from the backwash drainage extraction line 62.

As a specific example of performing the backwashing, an arbitrary gas such as air or nitrogen is used as the gas, as shown in FIG.
, The valve 85 is first opened for 10 seconds and then
Close second. Thereafter, a method of repeating the cycle of opening for 10 seconds and closing for 10 seconds a plurality of times is exemplified. Of course, this 10 seconds is an example. Further, the holding time of opening and closing of the valve 85 may be different.

After performing the water backwashing, the gas-liquid mixing backwashing, and the gas backwashing, the vessel 50 is filled with water as shown in FIG. In this case, valves 63, 71, 81,
85 is closed and the valves 61, 73, 83 are opened, raw water is supplied from the raw water port 51 into the vessel 50, and the remaining gaseous concentrated water and initial permeated water are discharged through the gas vent lines 72, 82. When all the gas is discharged, the concentrated water and the permeated water start flowing out of the gas vent lines 72 and 82, so that the valves 73 and 83 are closed, and the operation returns to the water flow operation shown in FIG.

By performing the water backwashing, the gas-liquid mixed backwashing, and the gas backwashing, the spiral membrane module can be sufficiently backwashed, and the permeated water amount can be sufficiently recovered.

In order to increase the backwashing efficiency, it is preferable that the membrane module 40 is installed vertically so that the axial direction of the shaft is in the vertical direction.

In the above embodiment, the socket 25
A permeated water outflow portion is arranged on the outer peripheral side of the socket 25, and a concentrated water outflow portion is arranged inside the socket 25. Conversely, the inside of the socket 25 is used as the permeated water outflow portion, and the outer peripheral side of the socket 25 is concentrated water outflow. It may be configured to be a part.

[0045]

As described above, according to the method for backwashing a spiral-type membrane module of the present invention, a water collecting pipe is unnecessary, the flow resistance of permeated water is small, and the spiral-type membrane can have a large membrane area. The module can be backwashed efficiently.

[Brief description of the drawings]

FIG. 1A is a perspective view of a bag-like membrane of a spiral membrane module according to an embodiment, and FIG. 1B is a perspective view of FIG.
FIG. 3C is a cross-sectional view taken along the line B-C of FIG.

FIG. 2 is a cross-sectional view showing a method of winding a bag-like membrane of a spiral membrane module to which the backwashing method according to the embodiment is applied.

FIG. 3 is a perspective view showing an engagement relationship between a wound body and a socket of the membrane module of FIG. 1;

FIG. 4 is a side view of the spiral membrane module of FIG. 1;

FIG. 5 is a water flow diagram showing a method for backwashing a spiral-wound membrane module according to an embodiment.

FIG. 6 is a partially exploded perspective view showing the structure of a conventional spiral type membrane module.

[Explanation of symbols]

 Reference Signs List 10 bag-like membrane 11 first side 12 second side 13 third side 14 fourth side 15 flow path material 16, 17, 18 adhesive 19 fin 20 shaft 24 wound body 25 socket 29 Mesh spacer 30 Open part for permeated water outflow 31 Closed part for permeated water outflow prevention 40 Spiral type membrane module 50 Vessel 60 Raw water line 62 Backwash drainage extraction line 70 Concentrated water line 80 Permeated water line 72, 82 Gas vent line 84 Gas line

Claims (2)

[Claims] 1. A method for backwashing a spiral-type membrane module, wherein a permeated water flow path material is disposed inside the bag-like membrane, and a raw water flow path material is disposed between the bag-like membranes. In the module, the bag-shaped membrane is wound around a shaft to form a roll, raw water is supplied from one end face of the roll, and permeated water is taken out from the other end face of the roll. In the state where there is permeated water inside the wound body, a backwash gas is supplied to the permeated water side, and the remaining permeated water is caused to flow backward. A method for backwashing a spiral-wound membrane module, characterized in that the gas supply is continued until the gas flows. 2. The method according to claim 1, wherein the bag-like film is a first film.
It is a substantially rectangular shape having second, third and fourth sides, the first, second and third sides are sealed, the fourth side is partially open, and the remainder is A first side portion orthogonal to the fourth side portion is applied to a shaft to wind a bag-like membrane to form a wound body, and the fourth side portion is formed as a closed body. The second side facing the fourth side faces the front end of the wound body, and the raw water flow path between the bag-like membranes is located on the third side. The entire portion is sealed, and a portion overlapping the open portion of the bag-shaped membrane is a closed portion in the fourth side portion, and a portion overlapping the closed portion of the bag-shaped membrane is an open portion. A method for backwashing a spiral-wound membrane module, comprising: