JPH0857268A - Membrane device of immersion type membrane separator - Google Patents

Abstract

PURPOSE: To prevent the lowering of membrane separation effect caused by & the reduction of an effective membrane area or the damage to flat membranes caused by mutual rubbing generated when a flat membrane element is loosened by a water stream to change the water passing interval between the flat membranes, and narrow interval places are closed by a suspended substance in water. CONSTITUTION: In the membrane unit of an immersion type membrane separator wherein a pair of water passing interval spacers 31, 32 are superposed one upon another along both surfaces of each of flat membrane elements 11 and a large number of the flat membrane elements are stacked in a one-row laminated state so as to hold water passing intervals 18 by the water passing interval spacers, slope parts 34, 36 are provided to the surfaces 31A, 32A coming into contact with each of the flat membrane elements of a pair of the water passing interval spacers 31, 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a large number of flat membrane elements having flat membranes such as reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes, other polymer membranes and inorganic (alumina ceramic etc.) membranes. The present invention relates to a membrane unit of an immersion-type membrane separation device that performs membrane separation by immersing in a liquid in a dipping tank.

[0002]

2. Description of the Related Art Immersion type membrane separators can obtain permeated water by performing membrane separation with low energy by a water head difference based on the water depth in the immersion tank in which the membrane unit is immersed and the suction force of a suction pump. 5 to 8 show the applicant's Japanese Patent Application No. 5-263.
146 shows the immersion type membrane separation device proposed in No. 146, and the flat sheet membrane element 11 addressed to one of them is a flat and square tricot spacer composed of a tricot knitted fabric, a net spacer,
Flat membranes 13, 13 of the same size are superposed on both surfaces of a water-permeable channel spacer 12 such as a perforated plate spacer, and four peripheral edges thereof are sealed 14 by heat, adhesive bonding, high-frequency welding or the like to be integrally formed. A permeation chamber 11 ′ surrounded by a seal 14 is formed between the flat membranes 13 and 13. Each flat membrane element is provided with water collecting ports 15 and 15 at two corners in a diagonal direction inside which are surrounded by a seal 14. Reference numeral 16 denotes an elastic gasket which is arranged at a corner having the water collecting port 15 of the flat sheet membrane element and maintains a predetermined water passage interval 18 between two adjacent flat sheet membrane elements, and is a right angle corresponding to the corner of the flat sheet membrane element. It is a triangle or a quadrangle having two sides and has an opening 17 of the same size that communicates with the water collection port 15. Reference numerals 19 and 20 denote end plates before and after sandwiching a row of a large number of flat sheet membrane elements facing each other in a laminated state with a gasket 16 keeping a water passage distance therebetween, and having the same size as the membrane element. . Through holes 21 communicating with the water collecting ports 15 and 15 of the flat sheet membrane element are formed in each end plate at the same two corners. The through holes of the end plates 19 and 20 have a large diameter portion 22 having the same size as the water collecting port 15 of the flat sheet membrane element and the opening 17 of the gasket 16, and the remaining portion is a small diameter portion 24 through which the tightening bolt 25 passes.
It has become. Further, a connection port 23 opened to the outer surface is provided at the back of the large diameter portion 22.

In order to assemble the membrane unit, a predetermined number of flat membrane elements 11 are lined up in a row through a gasket 16 (the water collecting port 15 of the flat membrane element and the opening 17 of the gasket are communicated) and are communicated. Bolts 25 are passed through the water collecting ports 15 of all the flat sheet membrane elements and the openings 17 of all the gaskets in series, and through holes 21 are fitted to the respective end portions of the bolts 25, and the flat sheet membrane elements are provided at the front and rear end plates 19 and 20. 1
1, the gasket 16 is sandwiched, and the nuts 26 screwed into the respective ends of the bolt are tightened to the end plates 19 and 20, and the flat membrane element and the gasket are sandwiched to be integrated. An O-ring 27 is fitted to a portion of each end of the bolt 25 located inside the small diameter portion 23 of the through hole for sealing. As a result, the large diameter portion 22 of the through hole of the end plate and the opening 17 of the gasket
And the water passage holes 15 of the membrane element are connected in series, and two water passages 28 and 29 are formed to connect the permeation chambers 11 ′ of the individual flat sheet membrane elements.

In FIG. 7, the flat membrane element assembly (membrane unit) is immersed in the liquid of the dipping tank 1 so that one of the water channels is on the top and the other is on the bottom to form an immersion type membrane separation device. A flow sheet of one example is shown in which the suction pump P1 is attached to one of the connection ports 23 in the end plates 19 and 20 of the upper water channel 28.
The permeated water intake pipe 2 having the above is connected and the other connection port is closed with a plug. The water intake pipe branches into two downstream of the suction pump, one of the branch pipes 2a rises, and the water surface is the same as the water surface of the dipping tank 1 or from above to the permeate storage tank 3 provided above it. The other branch 2b of the branch pipe extends straight and opens into the drainage tank 4. The branch pipes 2a and 2b are provided with on-off valves V1 and V2 on the way. The replacement water supply pipe 5 that projects from above into the liquid in the storage tank 3 is connected to one of the connection ports 23 in the end plates 19 and 20 of the water channel 29 below the membrane unit, and the other connection port is Close with a stopper. Then, a chemical injection pipe 7 for injecting the chemical liquid in the chemical liquid tank 6 with a pump P2 is connected in the middle of the supply pipe 5. The supply pipe 5 is provided with an on-off valve V3 on the water channel 29 side of the connection point of the chemical injection pipe, and the immersion tank 1 is provided with a raw water supply pipe and a mud discharge pipe 8 at the bottom. To collect permeated water, open the on-off valve V1, close V2 and V3, and draw the suction pump P.
Drive 1 As a result, the suction in the pump and the liquid in the dipping tank due to the head difference cause the water flow interval between each flat membrane element to be 1
8 permeates the flat membrane 13, flows through the permeation chamber 11 ′, flows into the water collecting port 15, and enters the storage tank 3 through the water channel 28, the pipes 2 and 2 a. The permeated water is collected, and when a certain amount of cake adheres to the outer surface of the membrane, the on-off valve V1 is closed, V2 and V3 are opened, and the suction pump P1 and the chemical solution pump P2 are operated to perform cleaning. . As a result, the permeated water that fills the permeation chamber of the membrane unit is drawn by the suction pump, and the water channel 28, the pipes 2, 2b.
Flow into the drainage tank 4, and at the same time, the permeated water in the storage tank 3 flows toward the membrane unit in the replacement water supply pipe 5 due to the head difference from the immersion tank 1 and the suction of the suction pump, It merges with the chemical solution injected in 7 to form a cleaning solution having a predetermined concentration, and enters the permeation chamber through a series of water channels 29 without applying excessive pressure to the membrane. Thus, when the cleaning liquid is replaced with the permeated water in the permeation chamber, the operation of the suction pump P1 and the chemical liquid pump P2 is stopped, V2 is closed in addition to the opening / closing valve V1, and the cleaning liquid is generated by the head difference between the storage tank 3 and the dipping tank 1. It is sent to the permeation chamber, the cleaning liquid in the permeation chamber is permeated from the inner surface of the membrane to the outer surface, and the cake adhering to the outer surface is peeled off. Since the cleaning liquid permeates the membrane in the direction opposite to the permeated water, the cake easily peels off from the outer surface of the membrane and is removed. The removed cake is discharged from the dipping tank by opening the valve of the mud discharge pipe 8. After cleaning, close the open / close valve V1, V2,
V3 is opened, the suction pump P1 is operated, the cleaning liquid in the permeation chamber is sucked into the drainage tank 4, and at the same time, the permeated water in the storage tank is sucked by the suction pump and the head difference between the storage tank and the immersion tank is supplied to the supply pipe 5 To the permeate chamber, and the permeate replaces the cleaning liquid in the permeate chamber. After the permeate chamber is replaced with permeate, the on-off valve V1 is opened, V2 and V3 are closed, and the permeate water sampling process is restarted.

[0005]

A large number of flat sheet membrane elements are merely kept by a gasket sandwiched between a pair of corners each having a water collecting port in the angular direction so as to maintain a water passage interval. For this reason, the flat membrane element is slackened by the water flow as shown in FIG. 8, and it is not possible to maintain a uniform water passage interval between the membranes. This reduces the effective membrane area and the membrane separation efficiency. Furthermore, during the permeation water sampling process, the flat membrane element is bent and rubbed by the flat membrane elements due to the water flow such as the air lift circulation flow generated in the water passage space between the adjacent flat membrane elements due to the air diffusion from the lower part of the membrane. May be damaged.

[0006]

In view of the above, the present invention is designed to maintain a uniform water-passing distance between membranes by tensioning the flat membrane element in a lateral direction and stretching it. A pair of water passage spacers are stacked along the side, and in the membrane unit of the immersion type membrane separation device in which a large number of flat membrane elements are lined up in a stacked state in a row while maintaining a water passage distance by the water passage spacers, It is characterized in that an inclined surface portion is provided on a surface of each of the pair of water passage spacers that comes into contact with the flat sheet membrane element.

[0007]

1 to 3 show the membrane unit of the first embodiment of the present invention, FIG. 4 shows the membrane unit of the second embodiment, and FIG.
The same constituent elements as those in the conventional examples of 9 to 9 are designated by the same reference numerals. The flat sheet membrane element 11 used in both examples also has a seal 1
The water collecting port 15 is provided at the diagonal corners surrounded by 4.
15 have been opened.

Reference numeral 31 designates a water passage interval spacer which is overlapped along one side (for example, the left side portion) of the flat sheet membrane element, and 32 is a water passage interval spacer which is overlapped along the other side (for example, the right side portion) and has a length. It is almost the same as the side portion of the flat sheet membrane element, and is provided with an opening 33 that communicates with the water collecting port 15 of the flat sheet membrane element when they are stacked on one side and the other side of the flat sheet membrane element.

Adjacent two flat sheet membrane elements 11A of the water passage gap spacer 31 which overlaps on the left side of the flat sheet membrane element,
The contact surface 31A with the one sheet 11A of 11B is provided with a sloping surface portion 34 on the lower left side, and the contact surface 31B with the other flat sheet membrane element 11B is provided with a sloping surface portion 36 on the surface facing the above-mentioned sloping surface portion 34. And a projecting portion 35 whose both slope portions are parallel to each other is formed. Similarly, the contact surface 32A of the water gap spacer 32, which is overlapped on the right side of the flat sheet membrane element, with one sheet 11A of two adjacent flat sheet membrane elements 11A and 11B.
Is provided with a sloping slope portion 34 on the lower right side, and a contact surface 32B with the other flat sheet membrane element 11B is provided with a slope surface portion 36 on a surface facing the slope surface portion 34, and both slope surface portions are parallel to each other. The protrusion 35 is formed.

The protrusions 35 of the contact surfaces 31B, 32B of the water-passing spacers of the embodiments shown in FIGS. 1 to 3 have slopes 36 having an angle β with respect to the angle α of the slope 34, and both slopes are parallel to each other. (See FIG. 3). In addition, the projection 35 of the contact surfaces 31B and 32B of the water passage spacer of the embodiment of FIG.
Is a triangle having an obliquely outward cross section, and a triangular top portion 37 contacts the slope portion 34 through the flat membrane element.

Slopes 36 are provided on the left and right sides of the end plate 19 before and after assembling the membrane unit by finally fastening the bolts and nuts with the water-passing space interposed therebetween, and on the left and right sides of the end plate 20. Is provided with a slope 34.

The water passage spacer 31 is sandwiched on the left side between a number of flat membrane elements, the water passage spacer 32 is sandwiched on the right side, and the opening 33 of each spacer is aligned with the water collecting port 15 of the flat membrane element. As in the case of the conventional example, when the flat membrane element and the water passage spacer therebetween are sandwiched by the bolt 25, the nut 26, and the front and rear end plates 19 and 20, an integral membrane unit is assembled. The contact surfaces 31A and 31B and 32A and 32B contact each other through the flat membrane element, and at the same time, the protrusions 35 on the contact surfaces 31B and 32B connect the left and right edges of the flat membrane element to the contact surface 3
Bend outward along the outwardly facing sloped portions 34 at 1A and 32A. As a result, a force pulling to the left and right acts on the flat sheet membrane element addressed to each sheet, and the flat sheet membrane element becomes in a tensioned state.

Around the contact surfaces 31A, 32A and 31B, 32B of the water-passing spacers 31, 32, and around the large diameter portion 22 of the through-hole 21 opened on the opposite surfaces of the end plates 19, 20. If an annular projection 38 is provided around the water collecting port 15 of the flat sheet membrane element, the projection 38 of the flat sheet membrane element will not be caught when the membrane unit is assembled by tightening with bolts, nuts and front and rear end plates. It is possible to prevent the flat membrane element, the spacer for water passage, and the end plate from being displaced.
In this case, if the diameters of the annular projections are all the same, the projections may invade the flat sheet membrane element from both sides at the same position, which may impede the permeated water from flowing into the water collecting port 15.
As shown, one of the contact surfaces 31A and 32A, the annular protrusion 38 of the end plate 19, and the contact surfaces 31B and 32B and the annular protrusion 38 of the end plate 20 has a large diameter and the other has a small diameter. It is preferable that the flat membrane elements are erected at different positions.

The assembled membrane unit is immersed in water in the immersion tank 1 as in the conventional case, and the permeated water intake pipe 2 and the replacement water supply pipe 5 are connected to perform membrane separation. In the illustrated embodiment, the water collecting ports are provided at the diagonal corners of the flat sheet membrane element as in the conventional example, but the water collecting ports may be provided at the four corners. Of course, in that case, openings are provided at the upper and lower ends of each water passage spacer.

[0015]

As is apparent from the above, according to the present invention, the pair of adjacent flat sheet membrane elements 11A of the pair of water-passing spacers 31, 32 extending along one side and the other side of the flat sheet membrane element 11A. Slopes 34 are provided on the surfaces 31A and 32A that come into contact with, and the surface 3 that comes into contact with another flat sheet membrane element 11B.
1B and 32B are provided with the outwardly facing inclined surface portion 36 to form a protruding portion 35. Therefore, the water passage spacer 31
Between the flat membrane elements on the left side, and the water gap spacer 32 on the right side, and the bolt 25, the nut 26, and the front and rear end plates 19 and 20 form the flat membrane element.
When the integral membrane unit is assembled by sandwiching the water passage spacer between them, the contact surfaces 31A and 31 of the water passage spacer are
B, and 32A and 32B contact each other through the flat membrane element, and at the same time, the slope portions 36 on the contact surfaces 31B and 32B are located at the left and right edges of the flat membrane element along the slope portion 34 on the contact surfaces 31A and 32A. Bend outwards. As a result, a force pulling to the left and right acts on the flat sheet membrane element addressed to each sheet, and the flat sheet membrane element becomes in a tensioned state. As a result, the flat sheet membrane element does not loosen due to the water flow and maintains a uniform water passage distance between the membranes, and it is possible to completely prevent the membranes from rubbing and rubbing, thus maintaining an effective membrane area and exhibiting a predetermined membrane separation efficiency. .

[Brief description of drawings]

FIG. 1 is an explanatory view of a flat sheet membrane element, a water passage spacer, and an end plate according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of FIG.

FIG. 3 is a partial cross-sectional view of a state in which the membrane unit is assembled.

FIG. 4 is an explanatory diagram of a flat sheet membrane element, a water passage spacer, and an end plate according to a second embodiment of the present invention.

FIG. 5 is a perspective view in which a part of a flat sheet membrane element is peeled off.

FIG. 6 is an enlarged cross-sectional view of a part of the assembled state of the membrane unit.

FIG. 7 is a flow sheet of a membrane separation device using a membrane unit.

FIG. 8 is an explanatory view showing a state in which the flat sheet membrane element of the membrane unit is loosened by a water flow.

[Explanation of symbols]

 1 Immersion tank 2 Water intake pipe 3 Storage tank 4 Drainage tank 5 Supply pipe 6 Chemical liquid tank 7 Chemical injection pipe 8 Drainage pipe 9 Fresh water tank 10 Membrane unit 11 Flat membrane element 11A Flat membrane element 11B Flat membrane element 31 Water gap spacer 31A Through Water-space spacer contact surface with flat membrane 11A 31B Water-space spacer contact surface with flat membrane 11B 32 Water-space spacer 32A Water-space spacer contact surface with flat membrane 11A 32B Water-space spacer flat membrane Contact surface with 11B 33 Opening of water gap spacer 34 Slope of contact surface 31A, 32A 35 Projection of contact surface 31B, 32B 36 Slope of projection 35 37 Triangular top of projection 35 38 Ring protrusion

Claims (1)

[Claims] 1. A pair of water-permeable spacers are overlapped along one side and the other side of the flat sheet membrane element, and a large number of flat sheet membrane elements are laminated in a row while keeping a water-passing interval by the water-permeable gap spacers. The membrane unit of the immersion type membrane separation device, wherein in the membrane unit of the immersion type membrane separation device arranged side by side, a slope portion is provided on a surface of each of the pair of water-passing spacers that contacts the flat membrane element.