JP2005211790A - Spiral membrane element and reverse flow washing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spiral membrane element that enhances the durability at the time of reverse washing by improving the structure of the spiral membrane element, and to provide a reverse washing method. <P>SOLUTION: In the spiral membrane element that is provided with a cylindrical wound material R in which a separation membrane 1, a supply side passage material 2 and a penetration side passage material 3 are spirally wound in a laminated state at the surroundings of a central tube 5 with apertures and is further provided with a sealing part to prevent the mixing of the supply side fluid and the penetration side fluid, the separation membrane 1 that counters via the penetration side passage material 3 is provided with a stuck part 7 in which the membranes are locally stuck to each other at the separation area except the sealing part 11,12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a spiral membrane element that separates components suspended and dissolved in a liquid, and more particularly to a spiral membrane element having high durability in a backwashing process and a backwashing method thereof.

  Conventionally, as a fluid separation element used for reverse osmosis filtration, ultrafiltration, microfiltration, etc., for example, a supply-side channel material that guides the supply-side fluid to the surface of the separation membrane, a separation membrane that separates the supply-side fluid, and a separation membrane There is known a spiral membrane element in which a unit made of a permeate-side flow channel material that permeates through and separates a permeate-side fluid separated from a supply-side fluid to a central tube is wound around a perforated central tube.

  As shown in FIGS. 5 (a) to 5 (c), such a spiral membrane element generally has a structure in which the supply-side flow path material 2 is disposed while the separation membrane 1 is folded in two, and a permeation side. The separation membrane unit U is manufactured by stacking the flow path material 3 and applying adhesives 4 and 6 to the periphery (three sides) of the separation membrane to form a sealing portion that prevents mixing of the supply side fluid and the permeation side fluid. The unit U is manufactured by winding one or more units U around the central tube 5 in a spiral shape and further sealing the periphery of the separation membrane.

  As a result, as shown in FIG. 6, both ends of the separation membrane 1 facing each other through the permeate-side flow path member 3 are sealed by both-end sealing portions 11, and a plurality of both-end sealing portions 11 arranged in a spiral shape. Between these, the supply-side flow path material 2 is interposed. Moreover, the outer peripheral side edge part of the separation membrane 1 which opposes through the permeation | transmission side flow path material 3 is sealed by the outer peripheral side sealing part 12 along the axial direction. This example is a case where there are a plurality of membrane leaves (sealed envelope-like membranes), but there are cases where there is a single membrane leaf (see, for example, Patent Document 1).

  As such a spiral membrane element is used, the filtered separated matter adheres to the surface and inside of the separation membrane, and the performance gradually decreases. For this reason, periodic cleaning of the film is necessary, but the method can be roughly divided into chemical cleaning and physical cleaning. The former is a method of immersing in chemicals such as citric acid solution, oxalic acid solution, sodium hydroxide solution, sodium hypochlorite solution, and the latter is pressure with air bubbles or water from the opposite direction (support side) of the filtration side of the membrane. A method of backwashing (backwashing) to physically wash out the deposits by applying, or flushing the separated matter adhering to the surface of the separation membrane and the supply-side channel material in the opposite direction from one of the supply-side channel materials Washing is common. These washings impose a heavy load on the porous separation membrane. Chemical cleaning requires resistance to chemicals, and physical cleaning requires high back pressure resistance and holding power.

  Specifically, the operating method of the spiral membrane element is to supply a stock solution from one or both end faces of the spiral membrane element and take out the permeate from at least one opening of a perforated hollow tube. However, at the time of backwashing, the permeated liquid is introduced from at least one open end of the hollow tube, and the permeated liquid led to the outer peripheral surface of the hollow tube is disposed on the outer peripheral side and the other end side of the spiral membrane element. To drain. At this time, a high back pressure resistance is required for the envelope membrane of the spiral membrane element. As separation membranes capable of both physical washing and chemical washing as described above, separation membranes described in Patent Documents 2 to 3 are known.

However, these separation membranes are those in which the separation membrane material is joined to the porous reinforcing sheet in a thrown state, and the adhesion of the separation membrane material is enhanced by the anchor effect. It is an invention that prevents peeling from the reinforcing sheet. Therefore, it is not a technique for improving the durability during backwashing by improving the structure of the spiral membrane element.
Japanese Patent Laid-Open No. 10-341 JP 9-313905 A JP 2002-301342 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a spiral membrane element that can improve the durability during backwashing by improving the structure of the spiral membrane element, and a backwashing method thereof.

  The above object can be achieved by the present invention as described below.

  That is, the spiral membrane element of the present invention is a cylindrical wound body in which a separation membrane, a supply side channel material, and a permeate side channel material are spirally wound around a perforated central tube. A spiral membrane element provided with a sealing portion for preventing the supply-side fluid and the permeation-side fluid from mixing with each other, the separation membrane facing through the permeation-side flow path material is the sealing portion. It has the fixed part mutually fixed mutually in the isolation | separation area | region other than.

  According to the spiral membrane element of the present invention, the separation membranes facing each other through the permeate-side channel material are locally fixed to each other at the fixing portion of the separation region other than the sealing portion, so that the pressure ( (Back pressure) is applied uniformly, and durability during backwashing can be improved.

  In the above, the individual dimensions of the fixing portion are preferably 10 to 1500 mm in length in the axial direction and 10 to 100 mm in length perpendicular to the axial direction. Here, each dimension of the adhering portion is a dimension when the separation membrane is developed on a plane. According to this configuration, since the axial length of the adhering portion is moderate, it is possible to achieve a structure that does not hinder the flow of the permeate-side fluid during normal operation while maintaining the reinforcing effect at the time of backwashing. In addition, since the length perpendicular to the axial direction is appropriate, it is possible to minimize the decrease in effective membrane area during normal operation while maintaining the reinforcing effect during backwashing.

  On the other hand, the backflow cleaning method for a spiral membrane element of the present invention uses the above spiral membrane element so that a pressure higher than 0.01 MPa and lower than 0.5 MPa is generated at the inlet end of the central tube. The separation membrane is washed by this method.

  According to the backwashing method of the present invention, since the separation membranes facing each other through the permeate-side channel material use spiral membrane elements that are locally fixed to each other in a separation region other than the sealing portion, Since pressure (back pressure) is applied uniformly, durability during backwashing can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram showing an example of a method for producing a spiral membrane element of the present invention. FIG. 2 is a partially broken perspective view showing an example of the spiral membrane element of the present invention.

  As shown in FIGS. 1 to 2, the spiral membrane element of the present invention includes a separation membrane 1, a supply-side channel material 2, and a permeate-side channel material 3 around a perforated central tube 5 in a laminated state. And a cylindrical wound body R wound in a spiral shape, and a sealing portion for preventing mixing of the supply side fluid and the permeation side fluid. The sealing portion includes a both-end sealing portion 11 and an outer peripheral side sealing portion 12.

  As shown in FIG. 2, both ends of the separation membrane 1 facing each other through the permeate-side flow path member 3 are sealed by both-end sealing portions 11, and a plurality of both-end sealing portions 11 arranged in a spiral shape are interposed. Is provided with a supply-side channel material 2. Moreover, the outer peripheral side edge part of the separation membrane 1 which opposes through the permeation | transmission side flow path material 3 is sealed by the outer peripheral side sealing part 12 along the axial direction.

  In the present invention, the separation membrane 1 facing through the permeate-side flow path member 3 includes a fixing portion 7 that is locally fixed to each other in a separation region other than the sealing portions 11 and 12. And In the present embodiment, an example is shown in which the fixing portion 7 is elongated in a direction perpendicular to the axial direction at the center of the separation membrane 1 in the axial direction.

  In the present invention, it is preferable to form the dotted fixed portions 7 as described later. Further, the individual dimensions of the fixing portion 7 are preferably 10 to 100 mm in the axial length and 10 to 100 mm in the length perpendicular to the axial direction for the above-mentioned reasons. Is more preferably 20 to 50 mm, and the length perpendicular to the axial direction is more preferably 20 to 50 mm.

  The cylindrical wound body R is formed by spirally winding the separation membrane 1, the supply-side channel material 2, and the permeate-side channel material 3 around the perforated center tube 5. It can be manufactured by a step of forming the rotating body R and a step of forming a sealing portion for preventing mixing of the supply side fluid and the permeation side fluid. Specifically, for example, it can be manufactured by the embodiment shown in FIG. 1A is a plan view of the separation membrane unit U, FIG. 1B is a front view of the separation membrane unit U, and FIG. 1C shows a state before the separation membrane unit U is stacked and wound. FIG.

  First, as shown in FIGS. 1A to 1B, the supply side flow path member 3 and the permeate side flow path member 3 are stacked while the separation membrane 1 is folded in half, and the supply fluid and A separation membrane unit U is prepared in which adhesives 4 and 6 for forming sealing portions 11 and 12 for preventing permeation of the permeated fluid are applied to both end portions in the axial direction of the permeation-side flow path member 3 and the winding end portion. . At this time, the adhesive 7a for forming the adhering portion 7 is similarly applied. A protective tape may be attached to the fold portion of the separation membrane 1.

  As the separation membrane 1, a reverse osmosis membrane, an ultrafiltration membrane, a microfiltration membrane, or the like can be used. However, in the present invention, separation of the separation membrane layer due to back pressure tends to be a problem, and the separation membrane layer becomes a porous reinforcing sheet. This is particularly effective in the case of formed ultrafiltration membranes, microfiltration membranes, and reverse osmosis membranes.

  For the supply-side channel material 2, a net-like material, a sheet-like material having irregularities, or the like can be used. A net-like or knitted material or the like can be used for the permeate-side channel material 3. The perforated center tube 5 only needs to have an opening around the tube, and any conventional tube can be used.

  As the adhesives 4, 6, and 7a, any conventionally known adhesives such as urethane adhesives and epoxy adhesives can be used. Moreover, it is also possible to form only any one of the sealing parts 11 and 12 using a hot-melt-adhesive, a heat-fusion-type adhesive tape, a heat-fusible sheet | seat, etc. In addition, when forming the fixing | fixed part 7 with the adhesive agent 7a, it will be in the state in which the permeation | transmission side flow path material 3 intervenes between separation membranes 1 mutually.

  Next, as shown in FIG. 1 (c), a plurality of the separation membrane units U are stacked and wound around the perforated central tube 5 in a spiral shape, and then the adhesives 4, 6, 7a, etc. The cylindrical wound body R is obtained by curing with heat. At that time, the periphery of the central tube 5 may be sealed at the same time. Both ends of the cylindrical wound body R are trimmed as necessary in order to adjust the axial length.

  The quantity when the separation membrane unit U is stacked is determined according to the required permeation flow rate and may be one or more layers. However, in consideration of operability, the upper limit is about 50 layers. In addition, the winding number of each separation membrane unit U decreases as the number of stacked separation membrane units U increases.

  The spiral membrane element of the present invention is usually constrained by an exterior material and does not expand in diameter, but the exterior material is formed by winding one or more sheets around the surface of the cylindrical wound body R. Can do. As the exterior material, polyester, polypropylene, polyethylene, polyvinyl chloride, glass fiber cloth, or the like can be used.

  The spiral membrane element of the present invention may be further provided with a perforated end member for preventing deformation (telescope or the like), a sealing material, a reinforcing material, and the like as necessary.

  On the other hand, the backflow cleaning method for a spiral membrane element of the present invention uses the above spiral membrane element so that a pressure higher than 0.01 MPa and lower than 0.5 MPa is generated at the inlet end of the central tube. In this way, the separation membrane is washed.

  By this cleaning, the fluid permeates backward from the permeation side of the separation membrane to the supply side, and the contaminants deposited on the membrane surface can be lifted. After that, pollutants accumulated on the membrane surface by flushing on the membrane surface are effectively discharged out of the system from multiple nozzles of the vessel cell, so that stable operation can be performed while maintaining a high permeation flux over a long period of time. Can do.

  The fluid used for backwashing is preferably a liquid that does not contain floating and dissolved components, and may be any of pure water, ultrapure water, permeated water of the element, and the like. Such a fluid can be supplied from one or both ends of the central tube, and the pressure is applied to the inlet end of the central tube. A preferable pressure is 0.02 to 0.2 MPa at the inlet end of the central tube.

[Other Embodiments]
(1) In the above-described embodiment, an example in which one fixing portion is elongated in the direction perpendicular to the axial direction at the center in the axial direction of the separation membrane is shown. In the present invention, FIG. You may form the adhering part 7 of a shape as shown to (c). In the present invention, it is preferable that the fixing portions 7 are arranged uniformly so that pressure (back pressure) is applied as evenly as possible to the separation region of the separation membrane 1.

  FIG. 3A shows a structure in which the fixing portion 7 is extended from the outer peripheral side sealing portion 12 to the central tube 5 when the single fixing portion 7 is formed to be elongated in a direction perpendicular to the axial direction. is there. In FIG. 3B, the two fixing portions 7 are elongated in the direction perpendicular to the axial direction. In FIG. 3C, three fixing portions 7 are elongated in a direction perpendicular to the axial direction so as to be separated from the outer peripheral side sealing portion 12 and the central tube 5. Thus, when forming the elongate and continuous adhering part 7, the space | interval (distance) has preferable 50-500 mm.

  Moreover, in this invention, you may form the dotted | punctate fixed part 7 as shown to Fig.4 (a)-(c). In FIG. 4A, one fixing portion 7 is formed in the approximate center of the separation region of the separation membrane 1. In FIG. 4B, four fixing portions 7 are formed on the diagonal line of the separation region of the separation membrane 1. In FIG. 4C, nine fixed portions 7 are formed on the diagonal line of the separation region of the separation membrane 1. Thus, when forming the adhering part 7 in the shape of a dot, the space | interval (distance) has preferable 150-700 mm.

  (2) In the above-described embodiment, an example in which an adhesive is used when forming a fixing portion between separation membranes has been shown. However, in the present invention, a hot-melt adhesive, a heat-fusion adhesive tape, and a double-sided adhesive tape It is also possible to use a heat-fusible sheet or the like. That is, the fixing portion in the present invention can be formed by adhesion, fusion, pressure bonding, or the like.

  Also, when forming the fixing part between the separation membranes, a heat-fusible resin material is used as the permeate side channel material without using an adhesive or the like, and the separation membranes are separated by the permeate side channel material. It is also possible to form the fixing portion by fusing. In that case, it is preferable that the permeate-side flow path material is made of a resin material having a low melting point than the material constituting the separation membrane. As a result, many fixing portions can be formed, and the pressure during backwashing can be made more uniform.

  (3) In the above-described embodiment, as shown in FIG. 1, the permeation-side channel material 3 is stacked on the separation membrane 1 folded in half so as to sandwich the supply-side channel material 2, and the adhesive 4 In the present invention, it is also possible to apply the adhesives 4 and 6 on the separation membrane 1 that is folded in two on the permeate-side channel material 3. Further, instead of the bifurcated separation membrane 1, two separation membranes 1 may be used to sandwich the supply-side flow path material 2 and a sealing portion may be provided also on the winding start side. Furthermore, the outer peripheral side sealing part 12 may be made unnecessary by using the continuous separation membrane 1.

  (4) In the above-described embodiment, as shown in FIG. 1, an example in which a spiral membrane element including a plurality of membrane leaves is manufactured using a plurality of separation membrane units U has been described. A spiral membrane element including one membrane leaf may be manufactured using a set of separation membrane units U.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

[Example 1]
A spiral membrane element (diameter 30 mm, length 1000 mm, urethane adhesive) in which a linear adhering portion (width 30 mm, length 1000 mm, urethane adhesive) is formed at the center of the polyvinylidene fluoride porous ultrafiltration separation membrane by the manufacturing process as shown in FIG. 201 mm, an axial length of 1016 mm, a leaf length of 750 mm, and a leaf number of 28) were produced. This spiral membrane element was housed in a container, and the separation membrane was washed for one month by backflow of pure water so that pressures of 0 MPa and 0.2 MPa were repeatedly generated at one end of the central tube. Thereafter, an airtight holding test was performed, and the durability of backwashing was evaluated by the airtight holding performance. As a result, there was no deterioration in airtightness due to breakage of the separation membrane.

[Example 2]
A spiral ultrafiltration membrane element was prepared in the same manner as in Example 1 except that the fixing parts (diameter 30 mm, urethane adhesive, 4 pieces) shown in FIG. Was evaluated. As a result, there was no deterioration in airtightness due to breakage of the separation membrane.

  Using this, the pressure at which the backwashing was increased stepwise and the pressure at which the separation membrane was damaged was examined, and it was found that it was durable up to twice the pressure of the spiral membrane element of Example 1. It was.

[Comparative Example 1]
Spiral membrane elements were prepared in exactly the same manner as in Example 1 except that no fixed portion was formed, and the durability of backwashing was evaluated. As a result, the airtightness was lowered due to the breakage of the separation membrane.

Process drawing which shows an example of the manufacturing method of the spiral type membrane element of this invention The partially broken perspective view which shows an example of the spiral type membrane element of this invention The principal part expanded view which shows the other example of the spiral type membrane element of this invention The principal part expanded view which shows the other example of the spiral type membrane element of this invention Process drawing showing an example of a conventional method for manufacturing a spiral membrane element Partially broken perspective view showing an example of a conventional spiral membrane element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separation membrane 2 Supply side flow path material 3 Permeation side flow path material 4 Adhesive 5 Center pipe 6 Adhesive 7 Adhering part 7a Adhesive 11 Both ends sealing part 12 Outer peripheral side sealing part R Cylindrical winding body U Separation membrane unit

Claims (3)

A separation membrane, a supply-side flow path material, and a permeate-side flow path material are provided with a cylindrical wound body spirally wound around a perforated central tube in a laminated state, and a supply-side fluid and a permeation-side fluid In the spiral membrane element provided with a sealing portion to prevent mixing,
The spiral separation type membrane element, wherein the separation membranes facing each other through the permeate-side flow path member are provided with fixed portions that are locally fixed to each other in a separation region other than the sealing portion.   2. The spiral membrane element according to claim 1, wherein each of the fixed portions has an axial length of 10 to 1500 mm and a vertical length of 10 to 100 mm.   A spiral membrane that uses the spiral membrane element according to claim 1 or 2 to wash the separation membrane by backflow so that a pressure higher than 0.01 MPa and lower than 0.5 MPa is generated at the inlet end of the central tube. Element backwashing method.

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