JPH0924255A - Spiral membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase permeated water by flowing raw water at a high flow speed through all spiral membrane elements of a plurality of steps which are filled in a line in the front and the rear in a vessel while raw water is brought into contact with the membranes. SOLUTION: A plurality of spiral membrane elements 1 having the water collection pipes 7 of permeated water in the center parts are held in a line in the front and rear direction in the inside of a cylindrical vessel 10 which is slender in the front and rear direction. The external circumference of each element and the internal circumference of the vessel are sealed. Thereby, the water collection pipes of the front and rear spiral membrane elements are connected in series. Raw water is pressurized and supplied from the the front end of the vessel to the inside thereof and successively passed from the spiral membrane elements of the front step to the spiral membrane element of the rear step. Water permeated through the membranes is introduced into the water collection pipe. Permeated water and concentrated water are separated and discharged from the rear end of the vessel. The sectional area of the flow path for raw water in the spiral membrane elements of a plurality of steps which are arranged in the front and the rear in the vessel is gradually made small from the front toward the rear.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to reverse osmosis (RO).
Membranes, spiral membrane elements composed of MF membranes and UF membranes are accommodated in a row in the front-back direction inside a cylindrical vessel elongated in the front-back direction, and trace organic components such as trihalomethane precursors in raw water and dissolved inorganic substances The present invention relates to a spiral membrane module for efficiently separating membrane components by filtration to collect permeated water such as ultrapure water for cleaning semiconductor elements.

[0002]

2. Description of the Related Art A spiral membrane element is a sheet-shaped permeated water flow path spacer, a membrane, a sheet-shaped raw water flow path spacer, and another membrane, which is wound around a water collecting pipe in a laminated state. It is configured with. For example, FIG.
The water collecting pipe 7 having the water collecting hole 7 ′ will be described with reference to FIG.
On the other hand, one end of the flow path spacer 3 of the permeated water having a width slightly narrower than that of the flow path spacer of the raw water is wound around, and the other end is spread, while the separation membrane such as the RO membrane is placed at the center. A raw water flow path spacer 5 is sandwiched between two membranes 2, 2 that are formed by folding back, and the folded back portion 2 ′ of the membrane is arranged on the permeated water flow path spacer 3 so as to contact the water collecting pipe. . Then, an adhesive is applied to the peripheral portion of the film, and the film and the two kinds of spacers 3 and 5 are wound together to form a paste-wound laminate 6. As a result, the flow path spacer 3 of the permeated water is interposed between the two films 2 and 2 whose peripheral portions are adhered.
Each end of the water collection pipe 7 projects from both ends of the laminated body.
Further, a water-impermeable sheet 8 is wound around and adhered to the outside of the paste-wound laminate. The permeate flow path spacer 3 is a tricot knitted cloth (for example, made of polyester) that forms an uneven surface, and the raw water flow path spacer 5 is a knitted or woven synthetic fiber net.

As shown in FIG. 7, this spiral membrane element is accommodated in a row in the longitudinal direction in a cylindrical vessel 10 elongated in the longitudinal direction, and the outer circumference of each element 1 and the inner circumference of the vessel are annular. The front end 7A of the water collecting pipe of the frontmost element 1-1 facing the front end of the vessel having the raw water supply port 11 is closed by attaching the cap 12 and the last element 1- N
The rear end portion 7B of the water collecting pipe having the concentrated water discharge port 13 facing the rear end of the vessel is directly or indirectly pierced and supported by the rear end wall of the vessel, and after the water collecting pipe of the other preceding element. The end portion and the front end portion of the water collecting pipe of the latter stage element are connected by the joint cylinder 14 to form a spiral membrane module.

As a result, the raw water supply port 1 at the front end of the vessel is
When raw water is press-fitted into the vessel from 1, the raw water flows through the spiral membrane element of each stage from the first stage to the last stage.
The permeated water that has flowed axially in the glue-wrapped laminate 6 and has permeated through the membrane 2 at that time is the flow path spacer 3 for the permeated water between the membranes.
Flowing in a spiral shape toward the center of the roll-shaped laminated body, permeating through the membrane in contact with the outer periphery of the water collecting pipe, and collecting holes in the water collecting pipe 7 of each stage element connected in series by the joint cylinder 14. Inflow from 7 '. Therefore, the permeated water flows out from the end portion 7B of the water collecting pipe that penetrates through the rear end wall of the vessel, and permeates the membrane of each stage element from the concentrated water discharge port 13 provided in the rear end wall. The concentrated water that did not flow out. The permeated water flowing out from the end of the water collecting pipe is ultrapure water obtained by separating and removing trace organic components such as trihalomethane precursors in raw water and dissolved inorganic components by membrane filtration as described above. Supply it as piping for cleaning water etc. to the required places.

[0005]

In this case, the amount of raw water flowing into the flow path spacer 5 of the former membrane element flows axially in contact with the membrane in the roll-shaped laminated body 6 of the membrane element, Whereas the total water amount of the permeated water that has permeated through the membrane and is collected in the water collecting pipe of the element and the concentrated water that cannot permeate through the membrane and flows out in the axial direction from the raw water flow path spacer,
The raw water flowing into the roll-up laminated body of the latter membrane element is the concentrated water flowing out from the raw water flow path spacer of the front-stage membrane element, and the amount of water flows into the roll-up laminated body of the front membrane element. The amount of the permeated water sampled in the water collection pipe of the preceding membrane element is smaller than the amount of the raw water to be collected.

In membrane filtration, the higher the flow rate of the raw water flowing in contact with the membrane 2 in the roll-shaped laminate, the more the concentration polarization can be prevented and the apparent salt rejection rate is high. However, the cross-sectional area of the raw water flow path of the spiral wound laminate of the spiral wound membrane element used in the conventional membrane module (the cross-sectional area of the space through which the raw water can pass in the paste wound laminate) is However, the membrane element in the latter stage is also fixed. For this reason, a larger amount of raw water flows into the roll-wound laminate of the preceding membrane element than it flows into the roll-wound laminate of the latter membrane element, and flows at a high flow rate in contact with the membrane. Although the polarization can be efficiently prevented, the raw water flowing into the roll-wound laminate of the former membrane element and the roll-wound laminate of the latter membrane element having the same cross-sectional area of the raw water flow passage (the raw water flow passage of the former membrane element Since the amount of concentrated water flowing out from the spacer) is smaller than that in the former stage, the flow velocity of the raw water flowing through the paste-shaped laminated body decreases, concentration polarization develops, and the salt rejection rate deteriorates. In addition, as the concentration polarization phenomenon progresses, scales are generated, and the amount of permeated water collected decreases.

As described above, due to the difference in the flow velocity of the raw water flowing in contact with the membrane, the amount of the permeated water taken in the former membrane element is large, and the amount of the permeated water taken in the latter membrane element is extremely reduced. Becomes more remarkable as the water pressure for supplying raw water into the front end of the vessel increases. Therefore, conventionally, the feed pressure of the raw water to the vessel is made low in order to make the amount of permeated water collected at each stage of the membrane element as equal as possible, but this allows the membrane to sufficiently exhibit the function of membrane filtration. It is not possible, and the operating efficiency of the device is extremely poor.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the conventional spiral membrane module, in which the permeated water is collected in the center of the inside of a cylindrical vessel elongated in the front-rear direction. Multiple spiral membrane elements with water pipes are housed in a row in the front-back direction, the outer circumference of each element and the inner circumference of the vessel are sealed, and the water collection pipes of the front and rear spiral membrane elements are connected in series, and the inside from the front end of the vessel The raw water pressurized and supplied to the spiral membrane element at the front stage is sequentially passed through the spiral membrane element at the rear stage, the permeated water that has permeated the membrane is introduced into the water collection tube, and the permeated water from the rear end of the vessel and the concentrated water are introduced. In the spiral membrane module that separates and discharges the water, the cross-sectional areas of the raw water flow paths of the spiral membrane elements in multiple stages before and after the arrangement in the vessel Characterized by being gradually decrease toward Luo subsequent stage.

[0009]

1 to 4 show an embodiment of the present invention, in which the same components as those of the conventional apparatus shown in FIGS. 5 to 7 are designated by the same reference numerals. In the first embodiment of FIG. 1, the diameter of the roll-shaped laminated body 6 of the membrane element 1-1 at the frontmost stage is A,
A water-impermeable sheet 8 is wound around the sheet and adhered thereto, an annular sealing material 9 is attached to the outside of the sheet, and the vessel 10 is sealed with the sealing material 9 and held. The cross-sectional area of the raw water flow passage of the second or subsequent membrane element roll-wound laminated body 6 is the same as that used in the first stage, and the same permeate flow channel spacer and raw water flow channel spacer are used as compared with the first stage. In order to make the size smaller, the diameter of the paste-wrapped laminate is made smaller than A, and the outside is surrounded by the impermeable envelope layer 21 so that the diameter of the impermeable envelope is the same as the diameter A of the frontmost roll-like laminate. Diameter. Then, the water-impermeable sheet 8 is wound and adhered to the outside of the water-impermeable envelope layer, an annular seal material 9 is attached to the outside of the sheet, and the inner periphery of the vessel is sealed and held by the seal material. In this case, the diameter of the roll-shaped laminate of the third stage membrane element 1-3 is 2
Diameter B of the roll-shaped laminated body of the membrane element 1-2 of the second stage
(However, C is smaller than B <A), and similarly, the diameter of the roll-shaped laminated body of the fourth-stage membrane element 1-4 is the diameter of the roll-shaped laminated body of the third-stage membrane element 1-3. D is smaller than C. Therefore, the thickness of the tubular wall increases as the water impermeable envelope layer 21 in the subsequent stage increases.

The water impermeable envelope layer 21 may be composed of two semi-cylindrical members which are themselves formed of a water impermeable material such as foamed resin, or a flexible sheet having a diameter smaller than A. A water-impermeable coating layer may be provided outside the glue-wrapped laminated body until the diameter becomes A, and when the sheet is water-absorbing, a water-impermeable coating material may be applied to both end surfaces.

As described above, in the first embodiment, the diameter of the paste-laminated laminate is made smaller in the latter membrane element to reduce the cross-sectional area of the raw water flow passage, and the raw water flowing into the paste-laminated laminate of the latter membrane element is made smaller. Even if the amount of water is smaller than that in the preceding stage, the flow velocity of the raw water flowing in contact with the membrane can be kept high.

In the second embodiment of FIG. 2, the permeated water flow channel spacers are the same in both the front and rear stages, but the thickness of the fibers 22 forming the net of the raw water flow channel spacer 5 is set to be thick d1 in the front stage. In the latter part, it is made thin d2. As a result, the thickness of the raw water flow path spacer becomes thinner in the latter stage, and the ratio of the cross-sectional area occupied by the raw water flow path spacer 5 in the paste-laminated laminate 6 becomes smaller in the latter stage membrane element. Therefore, although the diameters of the membrane elements in each of the front and rear stages are the same, the raw water flow channel spacers 5 are thinner in the latter stages, so that the raw water flow passage cross-sectional area of the roll-shaped laminate is the latter stage. The flow rate of the raw water flowing in contact with the membrane can be maintained at a high speed even when the amount of raw water flowing into the roll-wound laminated body of the latter membrane element is smaller than that in the former stage.

In the third embodiment of FIG. 3, the thickness of the permeated water flow path spacer 3 made of a tricot knitted cloth interposed between the membranes 2 is the same as that of the raw water flow path spacer in both the front and rear stages. The thickness of the front is T1 and the thickness of the rear is T2. Further, when the thickness of the flow passage spacer 3 in the latter stage is doubled from that in the former stage, the spacer of the thickness T1 may be arranged in the front stage and two spacers of the thickness T1 may be stacked to form the latter stage spacer. Therefore, the bag-shaped flat membrane body 4 in which the side edges of the two membranes 2 and 2 are adhered to each other and the permeated water flow path spacer 3 is sandwiched between them is thicker in the latter stage, and thus in the membrane filtration layer. Since it blocks the flow of raw water that tries to flow in, the cross-sectional area of the raw water flow path of the roll-wound laminated body becomes smaller in the latter stage while the diameter of the membrane elements in the front and rear stages is the same. Even if the amount of raw water flowing into the paste-laminated laminate is smaller than that in the preceding stage, the flow velocity of the raw water flowing in contact with the membrane can be kept high.

The fourth embodiment shown in FIG. 4 is the same as the second embodiment.
A composite of the third embodiment, the raw water flow path spacer 5 used in the membrane element of the preceding stage is as thick as in the second embodiment, and the permeated water flow path spacer 4 is as thin as in the third embodiment. The raw water flow path spacer 5 used for the subsequent membrane element is thin as in the second embodiment, and the permeate flow path spacer 4 is as thick as in the third embodiment. As a result, the raw water flow channel spacer used in the latter membrane element has a small cross-sectional area and the permeated water flow channel spacer that greatly blocks the flow of raw water that is about to flow into the glue roll laminate. Due to the effect, the raw water flow passage cross-sectional area of the roll-wound laminated body of the latter stage membrane element can be made sufficiently smaller than that of the former stage `` raw water flow passage cross-sectional area, and a small amount of raw water flowing into the roll-wound laminated body is obtained. Can be flowed at a high flow rate in contact with the membrane.

In each of the embodiments shown in FIGS. 1 to 4, the raw water flow passage cross-sectional area of the glue-wound laminated body is smaller than that of the first stage in the second stage and smaller than that of the second stage in the third stage. Although it was made smaller for the first stage, for example, the raw water flow passage cross-sectional areas of the first and second stages were made the same, and the raw water flow passage cross-sectional areas of the second and third stages were made smaller than that. The raw water flow passage cross-sectional areas of the membrane element may be put together to be the same and may be successively reduced.

[0016]

As is apparent from the above, in the spiral membrane module of the present invention, the raw water flow passage cross-sectional area of the roll-shaped laminated body of the front and rear membrane elements packed in a line in the vessel is made smaller toward the rear. Therefore, the raw water can flow at a high flow rate in contact with the membrane even in the latter membrane element in which the amount of raw water inflow is smaller than that in the former membrane element. Therefore, the concentration polarization phenomenon is prevented from occurring on the film surface, and the apparent rejection rate of salt is increased. Then, the water pressure of the raw water supplied to the front end of the vessel is increased, and the raw water is passed through the glue-wound laminated body of the membrane elements at each stage at a high speed, so that the permeated water can be further collected.

[Brief description of drawings]

FIG. 1A is an axial cross-sectional view of a first embodiment of the present invention, and FIG. 1B is a cross-sectional view of a front and rear membrane element of the same.

FIG. 2 (A) is a partial axial cross-sectional view of a second embodiment of the present invention, (B) is a perspective view of a part of a raw water flow path spacer used for the preceding membrane element of the same, C) is a partial perspective view of the flow path spacer of the raw water, which is also used for the latter membrane element.

FIG. 3A is a partial axial cross-sectional view of a third embodiment of the present invention, and FIG. 3B is a partial cross-sectional view of a permeate flow channel member used for the preceding membrane element of the same. (C) is a cross-sectional view of a part of a permeated water flow channel member that is also used in the latter-stage membrane element.

FIG. 4 is a partial axial cross-sectional view of a fourth embodiment of the present invention.

FIG. 5 is a perspective view of a water collecting pipe, a membrane body, and a raw water flow path member that constitute the membrane element in a disassembled state.

FIG. 6A is an enlarged axial sectional view of a part of a conventional membrane element, and FIG. 6B is a sectional view taken along line BB of the same.

FIG. 7 is an axial sectional view of a conventional membrane module.

[Explanation of symbols]

 1 Spiral Membrane Element 2 Membrane 3 Permeate Flow Channel Spacer 4 Membrane 5 Raw Water Flow Channel Spacer 6 Glued Laminate 7 Water Collection Tube 8 Impermeable Sheet 9 Seal 10 Vessel 11 Raw Water Inlet 12 Cap 13 Concentrated Water Outlet 14 Joint tube 21 Impermeable surrounding layer 22 Raw water flow path spacer fiber 23 Permeate flow path spacer ridge

Claims (1)

[Claims] 1. A plurality of spiral membrane elements, each having a permeate water collecting pipe in the center thereof, are housed in a row in the front-rear direction inside a vessel that is elongated in the front-rear direction, and the outer circumference of each element and the inner circumference of the vessel. In addition to sealing, the water collecting pipes of the front and rear spiral membrane elements are connected in series, and raw water pressurized and supplied from the front end of the vessel is sequentially passed from the front spiral membrane element to the rear spiral membrane element to form a membrane. The permeated water that has permeated through is introduced into the water collection pipe,
In a spiral membrane module that separates and discharges permeated water and concentrated water from the rear end of the vessel, the raw water flow passage cross-sectional areas of the spiral membrane elements in multiple stages before and after being arranged in the vessel are changed from the front stage to the rear stage. The spiral membrane module is characterized in that it is gradually reduced in size.