JP2018086638A - Spiral type separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral type separation membrane element which can restrict formation of scale and fouling phenomena, and exhibits a superior water production amount and removing performance over a long term.SOLUTION: A spiral type separation membrane element includes: a separation membrane comprising a main supply side surface and a permeation side surface, and forming a separation membrane pair by arranging both permeation side surfaces opposite each other; a supply side flow passage material provided between the supply side surfaces of the separation membrane; a permeation side flow passage material provided between the permeation side surfaces of the separation membrane; and a perforated water collecting pipe capable of collecting permeation water. In the spiral type separation membrane element, the supply side flow passage formed by the supply side flow passage material is at least disposed along a perpendicular direction with respect to a longitudinal direction of the perforated water collecting pipe. The supply side flow passage material comprises a plurality of mutually crossing threads, and thickness of the supply side flow passage material is 0.5 mm to 2.0 mm. Further, the permeation side flow passage material is arranged opposite the permeation side surface of the separation membrane, and the permeation side flow passage material comprises protrusions.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a spiral separation membrane element used for separating components contained in a fluid such as liquid or gas.

  In the technology for removing ionic substances contained in seawater, brine, and the like, in recent years, the use of separation methods using separation membrane elements is expanding as a process for saving energy and resources. Separation membranes used in separation methods using separation membrane elements are classified into microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, and forward osmosis membranes in terms of their pore sizes and separation functions. These membranes are used, for example, in the production of drinking water from seawater, brackish water and water containing harmful substances, industrial ultrapure water, wastewater treatment and recovery of valuable materials. It is properly used depending on the separation component and separation performance.

  Although there are various forms as the separation membrane element, they are common in that supply water is supplied to one surface of the separation membrane and permeated water is obtained from the other surface. The separation membrane element includes a large number of bundled separation membranes so that the membrane area per separation membrane element is increased, that is, the amount of permeated water obtained per separation membrane element is large. It is formed to become. As the separation membrane element, various shapes such as a spiral type, a hollow fiber type, a plate-and-frame type, a rotating flat membrane type, and a flat membrane integrated type have been proposed according to applications and purposes.

  For example, spiral separation membrane elements are widely used for reverse osmosis filtration. The spiral separation membrane element includes a center tube and a laminate wound around the center tube. The laminated body is a supply water side flow path material that supplies supply water (that is, treated water) to the separation membrane surface, a separation membrane that separates components contained in the supply water, and a separation membrane that permeates the supply water side fluid. It is formed by laminating permeate-side flow path materials for guiding the permeated fluid on the permeate side to the central tube. The spiral separation membrane element is preferably used in that a large amount of permeated water can be taken out because pressure can be applied to the supplied water.

  In recent years, as a means of achieving higher water production of a spiral separation membrane element, a separation membrane that fills a spiral separation membrane element by reducing the thickness of members such as a supply-side flow passage material, a separation membrane, and a permeation-side flow passage material A method of increasing the amount of water production by increasing the amount has been proposed. In particular, among the members, the supply-side flow path material is thick, the flow resistance generated when the spiral separation membrane element is operated is small, and even if the supply-side flow path material is further thinned, the increase in flow resistance is slight, A method has been adopted in which the supply-side channel material is thinned and the amount of separation membrane is increased.

  Specifically, Patent Document 1 proposes a spiral separation membrane element loaded with a supply-side channel material having a thickness of 0.1 to 0.5 mm. Patent Document 2 proposes a spiral separation membrane element having a thickness of 0.15 mm or more and 0.5 mm or less, a wide interval between intersections, and a flow path material having a low resistance on the transmission side. .

  Further, in order to improve the separation performance of the spiral separation membrane element, a flow path material member and a spiral separation membrane element structure that can enhance the turbulent flow effect on the membrane surface and suppress concentration polarization have been proposed.

  Specifically, Patent Document 3 and Patent Document 4 propose a spiral separation membrane element in which the turbulent flow effect on the membrane surface is increased by providing convex portions and grooves on the supply side surface of the separation membrane. .

JP-A-10-230140 Special table 2014-003170 gazette JP 2010-125418 A JP 2012-66239 A

  Conventional spiral element type separation membrane elements are used in response to the need for high water recovery and improved separation performance of spiral type separation membrane elements, as well as high recovery rate operation (recovery rate: ratio of the amount of permeated water to the amount of water supplied to the element). In the configuration, the flow rate of the supply water to the supply-side channel material is reduced, so that the fouling phenomenon in which contaminants adhere to the separation membrane surface is likely to occur, and the hardly soluble salt (scale) is likely to accumulate, and the continuous operation is in progress. However, there is a tendency for the water production performance and the separation function to decline.

  Therefore, an object of the present invention is to provide a spiral separation membrane element for a long period of time by suppressing generation of scale during operation and suppression of fouling.

  In order to achieve the above object, according to the present invention, a separation membrane having a supply side surface and a permeation side surface, and forming a separation membrane pair by arranging the permeation side surfaces to face each other, A supply-side flow path material provided between the supply-side surfaces of the separation membrane, a permeation-side flow path material provided between the permeation-side surfaces of the separation membrane, and a hole that can collect permeate A supply side flow path formed by the supply side flow path material is provided at least in a direction perpendicular to the longitudinal direction of the perforated water collection pipe, and the supply side flow path materials are mutually connected. It is provided with a plurality of intersecting yarns, the thickness of the supply side channel material is 0.5 mm or more and 2.0 mm or less, and the permeation side channel material is opposed to the permeation side surface of the separation membrane. A spiral separation membrane element is provided, wherein the permeate-side channel material has a protrusion. .

  Moreover, according to the preferable form of this invention, the spiral-type separation membrane element whose cross-sectional area ratio of the said permeation | transmission side flow-path material is 0.4-0.75 is provided.

  According to a preferred aspect of the present invention, there is provided a spiral separation membrane element characterized in that the protrusions are continuous in a direction perpendicular to the longitudinal direction of the water collecting pipe.

  Moreover, according to the preferable form of this invention, the spiral type separation membrane element whose intersection distance of the said thread | yarn is 8 mm or more is provided.

  According to the present invention, since concentration polarization is unlikely to occur, a fouling phenomenon in which contaminants adhere is less likely to occur, and furthermore, a region in which the feed water is stagnated is less likely to cause scale, and the amount of water produced and removability over a long period. Can be obtained.

It is a schematic diagram which shows an example of the conventional spiral type separation membrane element. It is another schematic diagram which shows an example of the spiral-type separation membrane element of this invention. It is another schematic diagram which shows an example of the spiral-type separation membrane element of this invention. It is a top view of the supply side channel material applied to the present invention. It is an example of the cross-sectional view of the permeation | transmission side channel material applied to this invention. It is a cross-sectional view explaining the form of the permeation | transmission side channel material applied to this invention. It is an example of the permeation | transmission side channel material applied to this invention. It is another example of the permeation | transmission side channel material applied to this invention.

  Next, an embodiment of the spiral separation membrane element of the present invention will be described in detail.

<Outline of spiral type separation membrane element>
In the spiral separation membrane element, a polymer net is mainly used as a supply-side channel material in order to form a supply-water-side fluid channel. In addition, a stacked type separation membrane is used as the separation membrane. Laminated separation membranes consist of a separation functional layer made of a crosslinked polymer such as polyamide, a porous resin layer made of a polymer such as polysulfone (porous support layer), polyethylene terephthalate, laminated from the feed water side to the permeate side. A non-woven substrate made of a polymer such as Further, in order to form a flow path for the permeate side fluid, a permeate side flow path material is used. As shown in FIG. 1, a general spiral separation membrane element includes a supply water side channel material 1 sandwiched between separation membranes 2, and a permeation side channel material 3 is laminated to form a set of units. The spiral separation membrane element 5 is wound around in a spiral shape.

  The spiral separation membrane element 5 includes a holed end plate 92 disposed at the first end and the second end and having holes. That is, the supply water 101 supplied from the first end of the spiral separation membrane element 5 is divided into permeated water 102 and concentrated water 103 by the separation membrane. The permeated water 102 is taken out from the second end of the spiral separation membrane element 5 through the water collection pipe 4. The concentrated water 103 flows out of the spiral separation membrane element 5 through the hole of the end plate 92 with the hole at the second end.

  In this invention, as shown in FIG. 2, the structure of the spiral separation membrane element 5B from which the flow of feed water differs is taken. In the general spiral type separation membrane element 5, the supply side flow path formed by the supply side flow path material is provided in a direction parallel to the longitudinal direction of the water collecting pipe 4, whereas in the spiral type separation membrane element 5B, at least It is provided in a direction perpendicular to the longitudinal direction of the water collecting pipe 4.

  The method for producing the spiral separation membrane element 5B is as follows. Specifically, the supply water side channel material 1 is sandwiched between the separation membranes 2, and the permeation side channel material 3 is laminated to form a set of units, which are wound around the water collecting pipe 4 in a spiral shape. Thereafter, edge cutting at both ends is performed, and a sealing plate (corresponding to the first end plate 91) for preventing inflow of supply water from one end is attached, and further, an end plate corresponding to the second end plate 93 is covered. A spiral separation membrane element can be obtained by attaching to the other end of the wound body.

  As the porous member 82, a member having a plurality of holes through which water can be passed is used. These holes 821 provided in the porous member 82 may be rephrased as supply water supply ports. As long as the porous member 82 has a plurality of holes, the material, size, thickness, rigidity and the like are not particularly limited. By adopting a member having a relatively small thickness as the porous member 82, the membrane area per unit volume of the spiral separation membrane element can be increased.

  In FIG. 2, the hole 821 provided in the porous member 82 is shown in a slit shape (straight), but a structure in which a plurality of holes such as a circle, a rectangle, an ellipse, and a triangle are arranged may be used.

  The thickness of the porous member 82 is preferably such a thickness that the separation membrane element can be filled with the amount of separation membrane necessary to achieve high water production, and the supply water flow path can be maintained, for example, 3.0 mm or less, More preferably, it is 2.5 mm or less, More preferably, it is 2.0 mm or less. Further, the porous member 82 may be a member having flexibility or flexibility that can be deformed so as to follow the outer peripheral shape of the wound body. More specifically, as the porous member 82, a net, a porous film, or the like can be applied. The net and the porous film may be formed in a cylindrical shape so that the wound body can be accommodated therein, or may be long and wound around the wound body.

The porous member 82 is disposed on the outer peripheral surface of the spiral separation membrane element 5B. By providing the porous member 82 in this manner, holes are provided on the outer peripheral surface of the spiral separation membrane element 5B. It can be said that the “outer peripheral surface” is a portion excluding the first end surface and the second end surface in the entire outer peripheral surface of the spiral separation membrane element 5B. In this embodiment, the porous member 82 is disposed so as to cover almost the entire outer peripheral surface of the wound body.
In the spiral type separation membrane element 5B, when loaded in a vessel and operated, the end plate at the first end is the end plate 91 without holes, so that the supply water is supplied into the spiral type separation membrane element 5B from the first end surface. Does not flow. The supply water 101 flows into the gap between the vessel and the spiral separation membrane element 5B. The supply water 101 is supplied to the separation membrane 2 from the outer peripheral surface of the spiral separation membrane element 5B through the porous member 82 in a direction perpendicular to the longitudinal direction of the water collection pipe. Supply water 101 supplied in this way is divided into permeated water 102 and concentrated water 103 by the separation membrane. The permeated water 102 is taken out from the second end of the spiral separation membrane element 5 </ b> B through the water collection pipe 6. The concentrated water 103 flows out of the spiral separation membrane element 5B through the hole of the end plate 93 with a hole at the second end.

  As in the spiral type separation membrane element 5B, the spiral type separation membrane element in which the supply side flow path formed by the supply side flow path material is provided at least in the direction perpendicular to the longitudinal direction of the perforated water collecting pipe, In the case of using a separation membrane pair in which the length of the side perpendicular to the longitudinal direction of the water collecting pipe is long with respect to the width of the element, the supply-side flow path and the longitudinal direction of the perforated water collecting pipe Compared with the conventional spiral separation membrane element installed in parallel direction, the cross section area of the feed water is narrowed and the linear velocity of the feed water passing through the separation membrane element is increased, so the membrane surface salt concentration of the separation membrane is increased. When the high recovery rate operation is performed, it is advantageous in that the concentration polarization phenomenon can be suppressed, and it is advantageous in that the fouling phenomenon in which contaminants adhere to the film surface can be suppressed.

  Furthermore, in this invention, as shown in FIG. 3, the structure of 5 C of spiral-type separation membrane elements from which the flow of feed water differs can also be taken. In the spiral separation membrane element 5C, the holeless end plate 91 at the first end of the spiral separation membrane element 5B is changed to a holed end plate 94, and both the outer peripheral surface and the first end of the spiral separation membrane element 5B are used. The structure which the supply water 101 flows can be taken.

  Furthermore, with regard to the arrangement of the holes of the holed end plate 93, if the opening is too large, the supply water may not flow uniformly to the supply side flow path and may be short-passed, so that the effect of the present invention appears. Can be provided around the water collecting pipe. The spiral separation membrane element 5C can be manufactured in the same procedure as the spiral separation membrane element 5B except that the end plate 91 is changed to the holed end plate 94.

  Similarly to 5B, the spiral-type separation membrane element 5C is provided with a supply-side flow path formed by a supply-side flow path material in a direction perpendicular to the longitudinal direction of the perforated water collecting pipe. Compared to the above, a configuration suitable for high recovery rate operation can be obtained.

<Separation membrane>
(Overview)
As the separation membrane 2, a membrane having separation performance according to the method of use, purpose and the like is used. The separation membrane 2 may be a single layer or a composite membrane including a separation functional layer and a substrate. In the composite membrane, a porous support layer may be further provided between the separation functional layer and the substrate.

  Here, the surface having the separation functional layer is referred to as the supply side surface, the surface opposite to the surface having the separation functional layer is referred to as the transmission side surface, and the separation is performed in such a state that the supply side surfaces face each other. The membrane is called a separation membrane pair.

(Separation function layer)
The separation function layer may be a layer having both a separation function and a support function, or may have only a separation function. The “separation function layer” refers to a layer having at least a separation function.

  When the separation functional layer has both a separation function and a support function, a layer containing, as a main component, a polymer selected from cellulose, polyvinylidene fluoride, polyether sulfone, and polysulfone is preferably applied as the separation functional layer.

  On the other hand, as the separation functional layer, a crosslinked polymer is preferably used in terms of easy control of the pore diameter and excellent durability. In particular, a polyamide separation functional layer obtained by polycondensation of a polyfunctional amine and a polyfunctional acid halide, an organic-inorganic hybrid functional layer, or the like is preferably used because it has excellent separation performance of components in the feed water 101. It is done. These separation functional layers can be formed by polycondensation of monomers on the porous support layer.

  For example, the separation functional layer can contain polyamide as a main component. Such a film can be formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide by a known method. For example, a polyfunctional amine aqueous solution is applied on the porous support layer, an excess polyfunctional amine aqueous solution is removed with an air knife or the like, and then an organic solvent solution containing a polyfunctional acid halide is applied. Condensation occurs and a polyamide separation functional layer is obtained.

(Porous support layer)
The porous support layer is a layer that supports the separation functional layer, and can also be referred to as a porous resin layer when the resin is a material.

  Although the material used for a porous support layer and its shape are not specifically limited, For example, you may form on a board | substrate with porous resin. As the porous support layer, polysulfone, cellulose acetate, polyvinyl chloride, epoxy resin or a mixture and laminate of them is used, and polysulfone with high chemical, mechanical and thermal stability and easy to control pore size. Is preferably used.

  The porous support layer is formed, for example, by casting an N, N-dimethylformamide (hereinafter referred to as DMF) solution of the above polysulfone on a base material to be described later (for example, a densely woven polyester nonwoven fabric) to a certain thickness. It can be produced by wet coagulation in water.

  The porous support layer is “Office of Saleen Water Research and Development Progress Report” no. 359 (1968). In addition, in order to obtain a desired form, the polymer concentration, the temperature of the solvent, and the poor solvent can be adjusted.

(Base material)
From the viewpoint of the strength, dimensional stability, etc. of the separation membrane 2, the separation membrane 2 may have a substrate. As the substrate, it is preferable to use a fibrous substrate in terms of strength and fluid permeability.

  As the substrate, a long fiber nonwoven fabric and a short fiber nonwoven fabric can be preferably used.

(Water permeability of separation membrane)
The separation membrane filled in the spiral separation membrane element of the present invention was cut into a 47 cm ² circular shape, and the feed water was a saline solution with a concentration of 200 ppm and a NaCl aqueous solution with a pH of 6.5, an operating pressure of 0.41 MPa, a temperature of 25 ° C., The separation membrane exhibits a water permeability of 0.5 m ³ / m ² / day or more when sampling for 1 minute is performed after operating for 15 minutes under a condition where the recovery rate is 1% or less. The higher the water permeability of the separation membrane, the greater the amount of supplied water, and accordingly the flow resistance of the flow path material increases.In the spiral separation membrane element of the present invention, even if a highly water permeable membrane is mounted, It is possible to reduce the flow resistance on the supply side with respect to the conventional element.

<Supply channel material>
(Overview)
The spiral separation membrane element includes a supply-side flow path member disposed so as to face the supply-side surface of the separation membrane body. The supply-side flow path material only needs to be formed so as to form a flow path for supplying supply water to the separation membrane body 2, and in order to suppress the concentration polarization of the supply water, the flow of the supply water is disturbed. It is preferable to be provided.

As the supply-side channel material, a member having a continuous shape such as a knitted fabric, a woven fabric, or a net is used. Among these, a net is preferably used from the viewpoint of securing the flow path of the supply water and suppressing concentration polarization. The net in the present application is a structure having a mesh shape in which a plurality of constituent fibers (warp yarn and yarn) intersecting each other are heat-sealed, and the warp and weft resin discharged from the holes provided in the extrusion die It is manufactured by bonding them in a molten state and then cooling and solidifying them.
As shown in FIG. 4, the supply-side channel material includes a fibrous row A composed of a plurality of fibrous objects A11 arranged in one direction, and a plurality of fibrous shapes arranged in a direction different from the fibrous row A. It consists of a fibrous row B composed of an object B12, and the fibrous object A intersects the fibrous object B at a plurality of points.

(Inclination angle of constituent fibers)
As the inclination angle e or f of the constituent fiber (yarn) of the supply side flow path material shown in FIG. 4 is closer to 0 ° or 180 °, the supply water flow path to the membrane surface becomes narrower. It is preferably not more than 0 °, and more preferably not less than 75 ° and not more than 105 ° with a low flow resistance.
(Thickness)
The thickness of the supply side channel material substantially corresponds to the intersection thickness of the fibrous materials A and B. If the thickness of the supply-side channel material is reduced, the linear velocity of the supplied water is increased and the flow on the membrane surface is disturbed, so that the concentration polarization layer is reduced and the separation performance of the spiral separation membrane element is improved. Further, the thinner the channel material, the more separation membranes that can be filled into the spiral separation membrane element, leading to an improvement in the amount of water produced by the spiral separation membrane element. However, if the thickness of the supply-side channel material is made too thin, impurities in the supply water and foulants such as microorganisms tend to block the supply-side channel. As a result, there are cases in which the amount of water generated by the element decreases, the flow resistance of the element increases, the power required for the pump for supplying the supply water increases, and the power cost increases and the element is damaged. This is not preferable. Therefore, the average thickness of the supply-side channel material is 0.5 mm or more and 2.0 mm or less, preferably 0.6 mm or more and 1.5 mm or less.

  The average thickness of the supply-side channel material is the average value of the values measured with a precision thickness gauge or the like for the intersection thicknesses of 10 or more randomly selected fibrous objects A and B, and is the sum of the measured values / It can be calculated from the number of measurement points.

Moreover, it is preferable that the intersection thickness of any of the fibrous materials A and B is 0.9 times or more and 1.1 times or less of the maximum average thickness of the supply-side channel material. This is because the performance of the reverse osmosis membrane can be exhibited uniformly by reducing the variation in the thickness of the supply-side channel material. (Constituent fiber diameter)
The constituent fiber diameter can be measured by observing with a commercially available microscope or the like. The fiber diameter of the fibrous object A11 and the fiber diameter of the fibrous object B12 shown in FIG. 4 are arbitrarily set to the widths c and d of the images obtained by projecting the respective fibrous objects on a plane parallel to the surface direction of the separation membrane. It is set as the average value which measured about 30 places. As the constituent fiber diameter of the supply-side channel material shown in FIG. 4 is smaller, the region where the supply water stagnates decreases, but the rigidity decreases. If the diameter is large, the rigidity is increased, but the area where the feed water is stagnated increases. From these balances, the constituent fiber diameter of the supply-side channel material is preferably 0.07 mm or more and 0.25 mm or less, and more preferably 0.25 mm or more and 1.0 mm or less. The fiber diameter of the fibrous material A and the fiber diameter of the fibrous material B may be the same or different as long as they are 0.25 mm or more and 1.0 mm or less.
(Intersection distance between constituent fibers)
The larger the intersection distance of the supply-side channel material shown in FIG. 4, the lower the flow resistance of the supply-side channel material and the smaller the pressure loss. In particular, during the high recovery rate operation, the membrane surface linear velocity decreases, and the supplied water tends to stagnate. A region where supply water stagnates mainly at the position of the intersection of the supply-side flow path members, and the salt concentration locally increases, so that scale may be easily generated on the membrane surface. The larger the intersection distance of the supply-side channel material is, the smaller the number of intersections of the supply-side channel material is, so the area where the supply water is stagnated is reduced, and scale is less likely to occur on the membrane surface. From the above, it is preferable that the interval between the supply side channel materials is 8 mm or more. Two types of intersecting point distances a and b are obtained for one gap in the supply side channel material. Among them, the shorter one a is selected, and the same measurement is performed at any 30 points. Is defined as the interval between the intersections of the constituent fibers.
(Cross-sectional shape of fibrous material)
Since it is important to increase the degree of turbulent flow around the separation membrane surface in the supply-side flow path, it is also possible to use an irregularly shaped fibrous material having a cross section that is not circular or elliptical. The “irregular” cross section includes all non-circular shapes. For example, in addition to a polygon, a Y-shaped, T-shaped, X-hour, star-shaped, or gear-shaped section includes a recess. Shape. Due to the presence of the recesses in the fibrous material, there will be a mixture of areas where the feed water is easy to flow and areas where it is difficult to flow around the supply side flow material. .

The formation of a fibrous material having a modified cross section is a technique well known in the art. For example, a fibrous material having various modified cross sections can be formed by changing the shape of the extrusion die as necessary. is there.
(Material)
The material of the supply-side channel material is not particularly limited, but a thermoplastic resin is preferable from the viewpoint of moldability, and polyethylene and polypropylene are particularly preferable because they hardly damage the surface of the separation membrane body and are inexpensive.

<Permeate channel material>
(Overview)
In the spiral separation membrane element of the present invention, a permeate-side channel material is disposed on the permeation side surface of the separation membrane. In this invention, the sheet | seat which provided the flow-path material function by uneven | corrugated the film and the nonwoven fabric as a permeation | transmission side flow path material, and the sheet | seat which has arrange | positioned the protrusion on the porous sheet like a nonwoven fabric are used.

(Cross-sectional area ratio)
The permeate-side channel material has a cross-sectional area ratio of 0.4 or more and 0 in terms of reducing the flow resistance of the permeate-side channel and forming the channel stably even under pressure filtration. .75 or less is preferable. Here, the cross-sectional area ratio of the permeate side channel material will be described. In FIG. 5, as an example, a sheet-shaped permeation-side flow path material is shown. However, when the permeation-side flow path material is loaded into the spiral separation membrane element, the permeation side along the direction parallel to the longitudinal direction of the water collecting pipe. Cut through the convex part of the flow path material, and with respect to the cross section, the product of the center P of the convex part and the center distance P (also referred to as the pitch) of the convex part and the height H0 of the permeate side flow path material, The ratio of the cross-sectional area S of the permeate-side flow path material between the center of the convex part and the center of the adjacent convex part is the cross-sectional area ratio.

  As a specific measurement method, the permeation-side channel material can be cut as described above, and calculation can be performed using a microscope image analyzer.

  By disposing a permeate-side channel material having a specific cross-sectional area ratio in the spiral separation membrane element of the present invention, the flow resistance of the permeate-side channel can be reduced. As a result, the permeation per unit membrane area Can be improved. The improvement in water permeability per unit membrane area means that the water-making property of the entire spiral separation membrane element is improved. When operating at a constant recovery rate, the flow passage material has a large permeation-side flow resistance. The effect of increasing the flow rate and line speed of the feed water compared to the spiral type separation membrane element that contains water is generated, and the concentration polarization is suppressed by increasing the membrane surface turbulence effect, and the amount of water production and removal performance of the spiral type separation membrane element Can be maintained for a long time.

(Thickness of permeate side channel material)
The thickness H0 of the permeate-side channel material in FIG. 6 is 0.1 mm or more and 1 mm in that the flow resistance of the permeate-side channel is reduced and the channel is stably formed even under pressure filtration. preferable. Various methods such as an electromagnetic method, an ultrasonic method, a magnetic method, and a light transmission method are commercially available for measuring the thickness, but any method may be used as long as it is a non-contact type. Randomly measure at 10 locations and evaluate the average value. By being 0.1 mm or more, it has strength as a permeate-side channel material and can be handled without causing the permeation-side channel material to be crushed or torn even when stress is applied. In addition, the number of separation membranes and flow passage materials that can be inserted into the element can be increased without impairing the surrounding property of the water collecting pipe when the thickness is 1 mm or less.

(Height, groove width, and groove length of the projection on the permeate side channel material)
The height H1 of the convex portion of the permeate-side channel material in FIG. 6 is 0.05 mm or more in terms of reducing the flow resistance of the permeate-side channel and forming the channel stably even under pressure filtration. 0.8 mm or less, and the groove width D is preferably 0.02 mm or more and 0.8 mm or less. The height of the convex portion and the groove width D can be measured by observing the cross section of the permeation-side channel material with a commercially available microscope or the like.

  The space formed by the height and groove width D of the convex portion and the laminated separation membrane can be a flow path, and the height and groove width D of the convex portion are in the above ranges, so that during pressure filtration The spiral separation membrane element excellent in pressure resistance and fresh water generation performance can be obtained while reducing the flow resistance while suppressing the membrane drop.

  Further, when the convex portions are arranged in both directions of MD and CD such that the convex portions are dot-like (see FIG. 7), the groove length E is set similarly to the groove width D. can do.

(Width and length of convex part of permeate side channel material)
The width W of the convex part of the permeate-side channel material in FIG. 6 is preferably 0.1 mm or more, and more preferably 0.3 mm or more. When the width W is 0.2 mm or more, the shape of the convex portion can be maintained even when pressure is applied to the permeate-side channel material during operation of the spiral separation membrane element, and the permeate-side channel can be stably provided. It is formed. The width W is preferably 1 mm or less, more preferably 0.7 mm or less. When the width W is 1 mm or less, a sufficient flow path on the permeate side of the separation membrane can be secured.

  The width W of the convex portion 6 is measured as follows. First, in one cross section perpendicular to the first direction (CD of the separation membrane), an average value of the maximum width and the minimum width of one convex portion 6 is calculated. That is, in the convex part 6 whose upper part is thin and whose lower part is thick as shown in FIG. 8, the width of the lower part and the upper part of the channel material are measured, and the average value is calculated. By calculating such an average value in at least 30 cross sections and calculating an arithmetic average thereof, the width W per film can be calculated.

  In addition, when the convex portions are arranged apart from each other in the MD and CD directions (see FIG. 7), such as the dot shape, the length X is set in the same manner as the width W. Can do.

(Permeate side channel material)
As the form of the sheet-like material, a knitted fabric, a woven fabric, a porous film, a nonwoven fabric, a net or the like can be used. Particularly in the case of a nonwoven fabric, a space serving as a flow path formed by fibers constituting the nonwoven fabric is widened. Therefore, it is preferable because water easily flows and, as a result, the water-making ability of the spiral separation membrane element is improved.

  Further, the polymer material that is the material of the permeation side flow path material is not particularly limited as long as it retains the shape as the permeation side flow path material and has little elution of components into the permeated water. Polyamides such as nylon, polyesters, polyacrylonitriles, polyolefins such as polyethylene and polypropylene, polyvinyl chlorides, polyvinylidene chlorides, polyfluoroethylenes and other synthetic resins can be mentioned, but they can withstand particularly high pressure In view of strength and hydrophilicity, it is preferable to use polyolefin or polyester.

  When the sheet-like material is composed of a plurality of fibers, the fibers may have a polypropylene / polyethylene core-sheath structure, for example.

(Flow path using permeate side flow path material)
When separation membranes are arranged on both surfaces of the permeate-side flow path member, the space of the convex portion adjacent to the convex portion can be a flow path of permeated water. For the flow channel, the transmission side flow channel material itself is shaped into a corrugated plate shape, rectangular wave shape, triangular wave shape, etc., or one surface of the transmission side flow channel material is flat and the other surface is processed to be uneven. Further, it may be formed by laminating other members on the surface of the permeate-side flow path material in an uneven shape.

(Permeate side channel material shape)
In the permeation-side channel material of the present invention, the convex portions forming the channel may be in the form of dots as shown in FIG. When the dot arrangement is arranged in a staggered pattern, the stress when receiving the supplied water is dispersed, which is advantageous in suppressing depression. In FIG. 7, columnar protrusions having a circular cross section (a plane parallel to the sheet plane) are illustrated, but the cross sectional shape is not particularly limited, such as a polygon or an ellipse. Moreover, the convex part of a different cross section may be mixed. Moreover, the uneven | corrugated shape which has a groove | channel where the groove | channel as shown in FIG. 8 was located in a line and continued may be sufficient. The groove is preferably continuous in the direction perpendicular to the longitudinal direction of the water collecting pipe in order to introduce permeate into the water collecting pipe at the shortest distance.

  The cross-sectional shape in the direction perpendicular to the winding direction may be a trapezoidal wall-like object having a change in width, an elliptical column, an elliptical cone, a quadrangular pyramid, or a hemispherical shape.

<Water treatment system>
The spiral separation membrane element of the present invention can be applied to a water treatment system such as an RO water purifier. In particular, when operating with a high recovery rate (ratio of permeate flow rate relative to the supply water amount), the salt concentration on the membrane increases, resulting in the formation of scales and a decrease in effective element pressure due to increased osmotic pressure. There is a tendency for the desalination rate and the amount of fresh water of the separation membrane element to decrease. However, in the spiral separation membrane element of the present invention, since the membrane surface linear velocity is improved, the concentration polarization is reduced, and furthermore, the amount of scale formation can be suppressed by reducing the area where the feed water is stagnated. Even if it is operated at a setting of 60% or more, it has excellent water freshening ability and desalting ability.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Intersection of supply side channel material)
For one gap in the supply-side channel material, the distance between the intersection of the fibrous material A constituting the supply-side channel material and the fibrous material B and the intersection not adjacent thereto is defined as a high-precision shape made by Keyence. Measurement was performed using the measurement system KS-1100, and the shorter of the obtained two types of distances was defined as the intersection distance. The same measurement was carried out for 30 voids, and the average value of the distances is shown in the table.

(Thickness of supply side channel material)
The intersection thickness of the mesh-like supply side channel material (net) made of fibrous materials A and B was measured at 30 locations using Mitutoyo Corporation's thickness gauge (part number 547-315), and the average value was measured on the supply side. The thickness of the channel material was used.
(Water generation amount of spiral separation membrane element)
For the spiral separation membrane element, an aqueous solution having a salt concentration of 200 ppm and a pH of 6.5 containing NaCl, CaCl ₂ , and Na ₂ SO ₄ is used as the feed water, and the operating pressure is 0.41 MPa and the temperature is 25 ° C. for 30 minutes. Sampling was performed for 1 minute after operation, and the amount of water per day was shown as the amount of water produced (m ³ / day). Also, when the total amount of water produced by the separation membrane element reached 3000 L, sampling was performed for 1 minute, and the amount of water per day was shown as the amount of water produced (m ³ / day).
(Recovery rate)
In the measurement of the amount of fresh water, the ratio of the supply water flow rate V _F supplied at a predetermined time and the permeated water amount V _P at the same time was taken as the recovery rate, and calculated from V _P / V _F × 100.
(Desalination rate (TDS removal rate))
For the feed water and the sampled permeate used in the operation for 1 minute in the measurement of the water production amount of the separation membrane element, the TDS concentration was determined by conductivity measurement, and the desalination rate was calculated from the following formula.

Desalination rate (%) = 100 × {1- (TDS concentration in permeated water / TDS concentration in feed water)}
(Preparation of permeate-side channel material having protrusions on the nonwoven fabric)
Using an applicator loaded with a comb-shaped shim with a slit width of 0.5 mm and a pitch of 0.9 mm, the temperature of the backup roll is adjusted to 20 ° C., and when the spiral separation membrane element is used, it is perpendicular to the longitudinal direction of the water collection pipe And when it is set as an envelope-like film, a highly crystalline PP (MFR 1000 g / 10 min, linearly or discontinuously so as to be perpendicular to the longitudinal direction of the water collecting pipe from the inner end to the outer end in the winding direction. The composition pellets consisting of 60% by mass of melting point 161 ° C.) and 40% by mass of low crystalline α-olefin polymer (Idemitsu Kosan Co., Ltd .; low stereoregular polypropylene “L-MODU · S400” (trade name)) It was applied on the nonwoven fabric linearly at a temperature of 205 ° C. and a running speed of 10 m / min. The nonwoven fabric had a thickness of 0.07 mm, a weight per unit area of 35 g / m ² , and an embossed pattern (a circle with a diameter of 1 mm, a lattice with a pitch of 5 mm).

In the table, the permeate side channel material is indicated as permeate side channel material A.
(Preparation of permeate-side channel material with a film having through holes)
Imprint processing and CO2 laser processing were applied to an unstretched polypropylene film (Toray manufactured by Toray Industries, Inc.) to obtain a permeate-side channel material having through holes. Specifically, an unstretched polypropylene film was sandwiched between metal molds having grooves formed by cutting, held at 140 ° C./2 minutes / 15 MPa, cooled at 40 ° C., and taken out from the mold.

  Subsequently, using a 3D-Axis CO2 laser marker MLZ9500, laser processing was performed on the concave and convex portions on the concave and convex surfaces of the concave and convex imprint sheet to obtain through holes. The through holes were provided in each groove with a pitch of 2 mm.

In the table, the permeate side channel material is indicated as permeate side channel material B.
(Scale adhesion)
The separation membrane element that reached a total water production of 3000 L was disassembled, and the ratio of the area of the portion where the scale was attached to the membrane area was calculated as a percentage (%). In the table, 50% or more of the above ratio is “adhered in large amounts”, 5% or more but less than 50% is “adhered in small amounts”, and less than 5% is “not adhering almost”. did.
(Transverse area ratio of permeate side channel material)
When the permeate-side channel material is loaded into the spiral separation membrane element, it is cut along the direction parallel to the longitudinal direction of the water collection pipe so as to pass through the convex part of the permeate-side channel material, and the cross section is analyzed with a microscope image Measure the distance between the center of the convex part and the center of the convex part (also referred to as the pitch) and the height of the permeate-side flow path material using the device. The ratio (cross-sectional area ratio) of the cross-sectional area of the permeate-side channel material occupying with the center was calculated. The same measurement was performed for 30 locations, and the average value of the distances is shown in the table.
Example 1
On a non-woven fabric made of polyethylene terephthalate fibers (fineness: 1 dtex, thickness: about 90 μm, air permeability: 1 cc / cm ² / sec, density: 0.80 g / cm ³ ), a 17.0% by weight DMF solution of polysulfone is 180 μm. A porous support layer (thickness) composed of a fiber-reinforced polysulfone support membrane, cast at a room temperature (25 ° C.), immediately immersed in pure water for 5 minutes, and immersed in warm water at 80 ° C. for 1 minute. 130 μm) roll was produced.

  Thereafter, the surface of the polysulfone layer of the porous support membrane was immersed in a 2.2% by mass aqueous solution of m-PDA for 2 minutes, and then slowly pulled up in the vertical direction. Furthermore, the excess aqueous solution was removed from the surface of the support film by blowing nitrogen from the air nozzle.

  Thereafter, an n-decane solution containing 0.08% by mass of trimesic acid chloride was applied so that the surface of the film was completely wetted, and then allowed to stand for 1 minute. Thereafter, excess solution was removed from the membrane by air blow, and washed with hot water at 80 ° C. for 1 minute to obtain a composite separation membrane roll.

  The separation membrane thus obtained was cut and the polypropylene net (thickness: 1 mm, intersection distance: 8 mm, fiber diameter: 0.15 mm, inclination angle: 90 °) shown in Table 1 was supplied to the supply water side channel material. As a result, the leaves were folded to produce a leaf.

  A permeation side channel material A (cross-sectional area ratio: 0.43) shown in Table 1 was laminated as a permeation side channel material on the permeation side surface of the obtained leaf, and a leaf adhesive was applied. A separation membrane pair is arranged so that the length of the side perpendicular to the longitudinal direction of the water collecting pipe is longer than the width of the element, and a water collecting pipe made of ABS (acrylonitrile-butadiene-styrene) (width: 298 mm). , Diameter: 17 mm, number of holes 8 spiral x 2 lines) spirally wound, and the outer peripheral surface of the envelope is continuously extruded into a cylindrical shape (thickness: 0.7 mm, pitch: 5 mm × 5 mm) Fiber diameter: 350 μm, projected area ratio: 0.13). After cutting both ends of the covered envelope so as to have a length of 254 mm, a sealing plate (corresponding to the first end plate 91) for preventing inflow of supply water from one end was attached. Thus, the supply water supply port was provided only on the outer peripheral surface of the spiral separation membrane element. Furthermore, an end plate corresponding to the second end plate 93 is attached to the other end of the covered envelope, and a concentrated fluid outlet is provided at the other end of the spiral separation membrane element. A membrane element was prepared. The obtained spiral separation membrane element was put in a pressure vessel, and each performance was evaluated under the above conditions at a recovery rate of 60%. Evaluation is carried out 30 minutes after the start of operation and when the total water production reaches 3000L, and when the total water production reaches 3000L, the spiral separation membrane element is disassembled and the proportion of the scale adhering part is measured. The results were as shown in Table 1. The effective membrane area in the table is a region where the separation function is not deactivated by the leaf adhesive in the separation membrane leaf.

(Example 2)
A spiral separation membrane element was produced in the same manner as in Example 1 except that a supply-side channel material having an intersection distance of 10 mm was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 3)
A spiral separation membrane element was produced in the same manner as in Example 1 except that the raw water supply part was the outer peripheral part and the first end face (the first end plate was changed to the holed end plate 94).

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
Example 4
The same procedure as in Example 1 was used except that a supply-side channel material having an intersection interval of 10 mm was used, and the raw water supply part was changed to an outer peripheral part and a first end face (the first end plate was changed to a holed end plate 94). A spiral separation membrane element was prepared.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 5)
A spiral separation membrane element was produced in the same manner as in Example 1 except that the permeation side channel material was changed to B.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 6)
A spiral separation membrane was used in the same manner as in Example 1 except that the permeate-side flow path material was B, and the raw water supply part was changed to the outer peripheral part and the first end face (the first end plate was changed to the holed end plate 94). An element was produced.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 7)
A spiral-type separation membrane element was produced in the same manner as in Example 1 except that a supply-side channel material having a thickness of 0.5 mm was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 8)
A spiral-type separation membrane element was produced in the same manner as in Example 1 except that a supply-side channel material having a thickness of 1.5 mm was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
Example 9
A spiral-type separation membrane element was produced in the same manner as in Example 1 except that a 2.0 mm-thick supply side channel material was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Example 10)
A spiral separation membrane element was produced in the same manner as in Example 1 except that the permeation-side channel material B having a cross-sectional area ratio of 0.65 was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Comparative Example 1)
A spiral separation membrane element was produced in the same manner as in Example 1 except that a supply-side channel material having a thickness of 4.0 mm was used.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Comparative Example 2)
Except that a 4.0 mm thick supply-side channel material was used and the raw water supply part was changed to the outer peripheral part and the first end face (the first end plate was changed to the end plate 94 with a hole), everything was the same as in Example 1. Thus, a spiral separation membrane element was produced.

When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.
(Comparative Example 3)
A spiral type separation membrane element was produced in the same manner as in Example 1 except that a supply-side channel material having a thickness of 100 μm was used.

  When the spiral separation membrane element was placed in a pressure vessel and each performance was evaluated under the same conditions as in Example 1, the results were as shown in Table 1.

1 Supply Water Side Channel Material 11 Fibrous Material A
12 Fibrous material B
DESCRIPTION OF SYMBOLS 101 Supply water 102 Permeated water 103 Concentrated water 2 Separation membrane 3 Permeation side channel material 4 Catchment pipe 5, 5B, 5C Spiral type separation membrane element 6 Convex part 7 Concave part 91 Endless plate 92, 93, 94 End plate with a hole , B Interstitial distance c of the fibrous material c, d Fiber diameter e, f of the fibrous material Inclination angle D of the constituent fibers of the supply side flow path material D Groove width E Groove length H0 Permeation side flow path material thickness H1 Permeation side flow The height S of the convex portion of the road material The cross-sectional area P of the convex portion of the permeate-side channel material The distance W between the center of the convex portion of the permeate-side channel material and the center of the adjacent convex portion Width X Length of convex part of permeate side channel material

Claims (4)

A separation membrane having a supply side surface and a permeation side surface, and forming a separation membrane pair by being arranged so that the permeation side surfaces face each other;
A supply-side flow path material provided between the supply-side surfaces of the separation membrane;
A permeate-side channel material provided between the permeate-side surfaces of the separation membrane;
A perforated water collecting pipe capable of collecting permeated water,
A supply-side channel formed by the supply-side channel material is provided at least in a direction perpendicular to the longitudinal direction of the perforated water collecting pipe,
The supply-side channel material includes a plurality of yarns that intersect each other,
The thickness of the supply side channel material is 0.5 mm or more and 2.0 mm or less,
The permeate-side channel material is provided to face the permeate-side surface of the separation membrane,
The permeate-side channel material has protrusions;
Spiral type separation membrane element. The spiral separation membrane element according to claim 1, wherein a cross-sectional area ratio of the permeate-side flow path material is 0.4 or more and 0.75 or less. The protrusion is continuous in a direction perpendicular to the longitudinal direction of the water collecting pipe,
The spiral separation membrane element according to claim 1 or 2. The intersection distance of the yarn is 8 mm or more,
The spiral separation membrane element according to any one of claims 1 to 3.

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