JP2018034089A - Separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane element having high water making quantity and removal performance and hardly generating scale even in high recovery rate operation.SOLUTION: In a separation membrane element comprising: a separation membrane having a supply side surface and a permeation side surface and being disposed so that the permeation side surfaces face each other; a supply side flow passage material disposed between the supply side surfaces of the separation membranes; and a permeation side flow passage material disposed between the permeation side surfaces of the separation membranes, a wound body is formed by winding the separation membrane, the supply side flow passage material and the permeation side flow passage material around a perforated center pipe, raw water is supplied from one end surface of the wound body in a longitudinal direction of the perforated center pipe and discharged from the other end surface of the wound body and the flow passage closing rate of the other end surface is 35-95%.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a separation membrane element used for separating components contained in a fluid such as liquid and 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, due to the increasing demand for reducing the fresh water generation cost, there has been a demand for higher performance of the separation membrane element. For example, in order to improve the separation performance of the separation membrane element, a flow path material member and a 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 1 and Patent Document 2 propose a separation membrane element that increases the turbulent flow effect on the membrane surface by providing convex portions and grooves on the supply side surface of the separation membrane.

JP 2010-125418 A JP 2012-66239 A

  In the separation membrane element described in Patent Literature 1 and Patent Literature 2, the effect of turbulent flow on the membrane surface can be enhanced and concentration polarization can be suppressed, but particularly high recovery rate operation (recovery rate: relative to the amount of water supplied to the element) When the ratio of water production is carried out, the flow rate of the feed water decreases as it approaches the feed water outlet, thereby reducing the turbulent flow effect on the membrane surface and insufficiently suppressing the concentration polarization. In addition, there is a problem that the removal performance is deteriorated and scale is likely to occur. Therefore, an object of the present invention is to provide a separation membrane element that has high water production and removal performance and is less likely to cause scale by suppressing concentration polarization even under high recovery rate operation.

  In order to achieve the object, the separation membrane element of the present invention is provided between a supply-side flow path material provided between the supply-side surfaces of the separation membrane and the permeation-side surface of the separation membrane. A permeation-side flow path member, and a wound body is formed by winding the separation membrane, the supply-side flow path material, and the permeation-side flow path material around a perforated central tube. Raw water is supplied from one end face of the wound body in the longitudinal direction of the hole center tube, discharged from the other end face of the wound body, and the flow path closing rate of the other end face is 35 to 95%. To do.

  According to the present invention, even when a high recovery rate operation is performed, sufficient membrane surface turbulence effect is obtained, concentration polarization is suppressed, high water production amount and removal performance are obtained, and scale is hardly generated. The lifetime of the membrane element can be improved.

It is a disassembled perspective view which shows a general separation membrane element. It is an example of the development of a general separation membrane element. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is an example of the expanded view of the separation membrane element of this invention. It is sectional drawing which shows the end surface of the separation membrane element of FIG.

  Next, embodiments of the separation membrane element of the present invention will be described in detail.

(1) Outline FIG. 1 is an exploded perspective view of the separation membrane element 1. As shown in FIG. 1, a general separation membrane element 1 includes a water collection pipe 2, a separation membrane 3, a supply-side channel material 4, a permeation-side channel material 5, and telescope prevention plates 71 and 72. The separation membrane 3, the supply side channel material 4, and the permeation side channel material 5 are overlapped to form a membrane unit 6. The supply-side channel material 4 forms a supply-side channel between the two separation membranes 3, and the permeation-side channel 5 forms a permeation-side channel between the two separation membranes 3. The membrane unit 6 is wound around the water collecting pipe 2 in a spiral shape to form a wound body 61. A filament or film (not shown) is wound around the wound body 61.

  Telescope prevention plates 71 and 72 are attached to both ends of the wound body 61 to prevent the wound body 61 from being deformed into a telescope shape. If so, the telescope prevention plates 71 and 72 may not be provided.

(2) Separation membrane <Overview>
As the separation membrane 3, a membrane having separation performance according to the method of use, purpose, etc. is used. The separation membrane 3 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.

<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 supply fluid 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 3, the separation membrane 3 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.

(3) Supply-side channel material The supply-side channel material 4 is disposed so as to be sandwiched between surfaces on the supply side of the separation membrane 3 and supplies the supply fluids 101 and 103 to the separation membrane 3 (that is, the supply side) Channel). Furthermore, in order to suppress the concentration polarization of the supply fluids 101 and 103, it is preferable to have a shape that disturbs the flow of the supply fluids 101 and 103.

  Note that the fluid supplied to one separation membrane element 1 and the fluid discharged from the supply-side flow path of the separation membrane element 1 are referred to as a supply fluid 101 and a concentrated fluid 103, respectively, for convenience.

  The supply-side channel material 4 may be a member having a continuous shape such as a film or a net, or is a discontinuity showing a projected area ratio that is greater than 0 and less than 1 with respect to the separation membrane 3. It may have a shape. Further, the supply-side channel material 4 may be separable from the separation membrane 3 or may be fixed to the separation membrane 3.

  Note that the material of the supply-side channel material 4 is not particularly limited, and may be the same material as the separation membrane 3 or a different material.

  In the supply side flow path, it is important to form the flow path stably, but it is also important to reduce the pressure loss because a larger amount of fluid passes through the supply side flow path than in the permeation side flow path. Therefore, the projected area ratio of the supply-side flow path member 4 is preferably 0.03 to 0.8, more preferably 0.05 to 0.5, and still more preferably 0.08 to 0.35. .

  The projected area ratio of the supply-side channel material 4 to the separation membrane 3 can be calculated by analyzing an image obtained by photographing the supply-side channel material 4 with a microscope or the like from a direction perpendicular to the membrane surface.

  When the thickness of the supply-side channel material 4 is large, the pressure loss is reduced, but when the element is made into an element, the membrane area that can be filled in the vessel is reduced. If the thickness is small, the pressure loss of the flow path will increase, and the separation characteristics and water permeation performance will deteriorate. Therefore, the fresh water generation capacity of the element is reduced, and the operation cost for increasing the fresh water generation amount is increased. Therefore, in consideration of the balance between the above-described performances and operating costs, the thickness of the supply-side flow path member 4 may be 80 to 2000 μm, and preferably 200 to 1000 μm.

  The thickness of the supply-side channel material 4 can be directly measured by a commercially available thickness measuring instrument, or can be measured by analyzing an image taken using a microscope.

  When the supply-side channel material 4 is a net, the net is composed of a plurality of yarns. The plurality of yarns intersect each other at the intersection, and the intersection portion has the largest thickness.

  The diameter of the yarn constituting the net may be constant in the length direction of the yarn, may be uniformly increased or decreased in the length direction, and may be a form in which increase and decrease are repeated. When the yarn diameter is repeatedly increased and decreased in the length direction, it is preferable that the plurality of yarns intersect at a point where the yarn diameter is the largest. A plurality of yarns intersect at a place where the yarn diameter becomes the largest, so that the pressure loss of the supply-side flow path can be reduced.

  The diameters of the intersecting yarns may be the same or different. When the diameters of a plurality of intersecting yarns are different, if the thickness is constant, a yarn having a small diameter has a large effect of reducing pressure loss, and a yarn having a large diameter has a large turbulent effect that disturbs the flow.

  From the balance between the pressure loss and the turbulence effect described above, the diameter of the yarn cross section constituting the net is preferably (minimum part diameter) / (maximum part diameter) of 0.1 or more and 0.7 or less, More preferably, it is 0.3 or more and 0.6 or less.

If the inclination angle of the yarn constituting the net is parallel to the flow direction of the supply fluid, the pressure loss can be reduced, but the effect of reducing concentration polarization is reduced. Although the loss increases, the concentration polarization reduction effect can be increased. Since the separation membrane element of the present invention partially closes the discharge end surface and / or the supply end surface of the supply fluid, the average flow direction of the supply fluid in the separation membrane element varies depending on the closing portion of the end surface and the closing rate. .
From the balance between pressure loss and concentration polarization reduction effect, the inclination angle of the yarn is preferably -60 ° or more and 60 ° or less with respect to the average flow angle of the supply fluid.

  The larger the distance between the intersections where the plurality of yarns intersect, the smaller the pressure loss, and the smaller, the greater the pressure loss. From these balances, the intersection distance is preferably 1.0 mm or more and 10 mm or less, more preferably 1.1 mm or more and 8 mm or less, and further preferably 1.2 mm or more and 5 mm or less.

  The cross-sectional shape of the yarn constituting the net is not particularly limited, and an ellipse, circle, triangle, quadrangle, irregular shape, etc. can be used. In addition, it is possible to suppress a decrease in the separation membrane performance due to the rubbing of the particles, to reduce the dead zone of the flow, and to suppress the concentration polarization, which is preferable. The projected area ratio of the portion where the net and the surface of the separation membrane are in contact with the separation membrane is preferably 0.01 or more and 0.25 or less, and more preferably 0.02 or more and 0.2 or less.

The material of the yarn constituting the net is not particularly limited as long as it can maintain the rigidity as the supply-side flow path material and does not damage the surface of the separation membrane. Polyethylene, polypropylene, polylactic acid, ethylene vinyl acetate copolymer, polyester, polyurethane, thermosetting elastomer and the like are preferably used.
(4) Supply-side channel end face FIG. 2 is a development view of the separation membrane element 1. FIG. 2 is a view showing a state of the water collecting pipe 2 and the separation membrane 3 before being wound around the water collecting pipe 2. In a general separation membrane element, the supply water is supplied from one end surface of the separation membrane winding body. Then, the concentrated water is discharged from the other end surface (103).

  Hereinafter, the one end face to which the supply water is supplied to the wound body is referred to as a supply water inflow end face, and the other end face of the wound body from which the concentrated water is discharged is referred to as a supply water discharge end face.

  In the separation membrane element of the present invention, the channel closing rate of the supply water discharge end surface (concentrated water end surface) of the supply side channel is 35 to 95%. Since the flow rate closing rate of the feed water discharge end face is within this range, the feed water flow path becomes narrower as it approaches the discharge end face, so even when operating at a high recovery rate, the membrane surface of the feed water The linear velocity can be kept large and concentration polarization can be suppressed. More preferably, the channel closing rate is 60% to 95%, and more preferably 75% to 95%.

  The flow path closing portion of the supply water discharge end face (concentrated water end face) of the supply side flow path is a winding direction as shown in FIGS. 3 and 4 when the direction perpendicular to the longitudinal direction of the water collecting pipe is the winding direction. 5 may be continuously closed from the outermost periphery to the inner periphery, or may be continuously closed from the innermost periphery to the outer periphery as shown in FIG. 5, as shown in FIGS. Thus, it may be closed intermittently in the winding direction. When the closing is intermittently performed in the winding direction, the length of one closing portion is preferably 1 to 100 mm. More preferably, it is 3 to 10 mm. Moreover, it is preferable that the length of one non-closing part (opening part) is 1-100 mm, More preferably, it is 3-10 mm.

  The length of one closing portion may be constant or may vary from the inside to the outside in the winding direction. Further, the length of one opening may be constant from the inner side to the outer side in the winding direction, may vary so as to gradually spread as shown in FIGS. 10 and 11, and is not illustrated. However, it may be varied so as to gradually narrow.

  The channel closing rate of the supply water inflow end surface of the supply side channel may be 50 to 90%. When the channel closing rate of the feed water inflow end face is within this range, the membrane surface velocity of the feed water can be increased, and concentration polarization can be suppressed. More preferably, the channel closing rate is 60% to 90%, and more preferably 75% to 95%.

  The flow channel opening of the supply water inflow end surface (supply water end surface) of the supply side flow channel may be continuously sealed from the innermost periphery to the outer periphery in the winding direction as shown in FIG. As shown in FIG. 8, it may be continuously sealed from the outermost periphery to the inner periphery, or may be intermittently sealed in the winding direction as shown in FIG.

  When the closing is intermittently performed in the winding direction, the length of one closing portion is preferably 1 to 100 mm. More preferably, it is 3 to 10 mm. Moreover, it is preferable that the length of one non-closing part (opening) is 1-100 mm, More preferably, it is 3-10 mm.

When the channel closing portion of the supply water discharge end surface (concentrated water end surface) of the supply side channel is continuously sealed from the outermost periphery to the inner periphery in the winding direction, supply as shown in FIG. It is preferable that the channel closing portion of the supply water inflow end surface (supply water end surface) of the side channel is continuously sealed from the innermost peripheral portion to the outer periphery in the winding direction. Such a closed portion is preferable because the dead zone of the flow can be reduced.
Moreover, when the flow path closing part of the supply water discharge end face (concentrated water end face) of the supply side flow path is continuously sealed from the innermost periphery to the outer periphery in the winding direction, as shown in FIG. Further, it is preferable that the channel closing portion of the supply water inflow end surface (supply water end surface) of the supply side channel is continuously sealed from the outermost peripheral portion to the inner periphery in the winding direction. Such a closed portion is preferable because the dead zone of the flow can be reduced.

  In addition, since the flow rate at the feed water discharge end face is smaller, the flow path closing rate at the feed water inflow end face and the feed water discharge end face is higher at the feed water discharge end face than at the feed water inflow end face. preferable.

  The flow path closing of the feed water discharge end face and the feed water inflow end face can be closed by sealing the vicinity of the end face with an adhesive or the like, or sealing the end face with a cap or the like.

  Sealing with an adhesive or the like can be performed by bonding with an adhesive or hot melt, or fusion with heat or laser. The adhesive used for sealing preferably has a viscosity in the range of 4 Pa · s to 15 Pa · s, more preferably 5 Pa · s to 12 Pa · s. When wrinkles occur in the separation membrane 3, the performance of the separation membrane element 1 may be reduced, but when the separation membrane 3 is wound around the water collecting pipe 2 because the adhesive viscosity is 15 Pa · s or less, Wrinkles are less likely to occur. Moreover, when the adhesive viscosity is 4 Pa · s or more, the outflow of the adhesive from between the separation membranes is suppressed, and the risk that the adhesive adheres to unnecessary portions is reduced.

  The amount of adhesive applied is preferably such that the width of the portion to which the adhesive is applied after the separation membrane 3 is wound around the water collecting pipe 2 is 5 mm or more and 30 mm or less. Thereby, a relatively large effective membrane area can be secured.

  The adhesive is preferably a urethane-based adhesive, and in order to make the viscosity in the range of 40 Pa · s to 150 Pa · s, the main component isocyanate and the curing agent polyol are isocyanate: polyol = 1: 1 to 1: 5. What was mixed in the ratio of these is preferable. The viscosity of the adhesive is measured with a B-type viscometer (JIS K 6833) by measuring the viscosity of the main agent, the curing agent alone, and a mixture in which the blending ratio is defined in advance.

  Sealing with a cap is performed by fitting a cap formed in a predetermined shape into the end of the wound body of the separation membrane element. At this time, it is necessary to prevent a gap from being formed between the end of the wound body of the separation membrane element and the flow path sealing portion of the cap. If the structure is such that no gap is formed between the end of the wound body of the separation membrane element and the flow path sealing portion of the cap and the end of the supply side can be sealed, the telescope prevention plate Can be used as a cap.

The material of the cap is not particularly limited as long as it can be formed into a predetermined shape and has a strength capable of sealing the supply fluid, but a resin is preferably used in terms of ease of molding, strength, and cost. . In these respects, ABS, polyvinyl chloride, polyethylene, and polypropylene are preferably used as the resin material.
(5) Permeation-side channel material The permeation-side channel material 5 is disposed so as to be sandwiched between the surfaces of the separation membrane 3 on the permeation side, and guides the fluid that has permeated the separation membrane 3 to the hole of the water collecting pipe 2. Play the role of forming the road.

  The permeate-side flow path material 5 reduces the flow resistance of the permeate-side flow path, suppresses the separation membrane 3 from dropping into the permeate flow path even under pressure filtration, and stably forms the flow path. The cross-sectional area ratio of the permeate-side channel material is preferably 0.3 or more and 0.75 or less, and more preferably 0.4 or more and 0.6 or less. There are no limitations on the type of permeate side channel material having a cross-sectional area ratio within this range. A concavo-convex sheet in which protrusions are arranged on such a porous sheet or a concavo-convex process of a film or a nonwoven fabric can be used.

  Although the pressure loss can be reduced if the thickness of the permeate-side channel material 5 is large, the membrane area that can be filled in the container of the separation membrane element 1 is reduced. If it is thin, the membrane area that can be filled in the separation membrane element 1 increases, but the pressure loss increases. The thickness of the permeate side channel material 5 is preferably 0.1 mm to 0.5 mm, more preferably 0.2 mm to 0.4 mm.

  By arranging the permeation side flow path material having a specific cross-sectional area ratio in the separation membrane element of the present invention, the flow resistance of the permeation side flow path can be reduced, and accordingly, the flow path material having a large flow resistance is obtained. When operated at the same recovery rate as that of the separation membrane element to be included, the flow rate of the feed water is increased and the concentration polarization can be reduced. In particular, the decrease in the concentration polarization and the generation of scale can be suppressed under the high recovery rate operation.

  A general separation membrane element operates at a recovery rate of 30% or less. However, the separation membrane element of the present invention can operate stably even at a recovery rate of 35% or more. In contrast, superiority can be expressed.

  Although the pressure loss can be reduced if the thickness of the permeate-side channel material 5 is large, the membrane area that can be filled in the container of the separation membrane element 1 is reduced. If it is thin, the membrane area that can be filled in the separation membrane element 1 increases, but the pressure loss increases. The thickness of the permeate side channel material 5 is preferably 0.1 mm to 0.5 mm, more preferably 0.2 mm to 0.4 mm.

  The thickness of the permeation side channel material 5 can be directly measured by a commercially available thickness measuring instrument.

  The material of the permeate side channel material 5 may be any material that can be easily wound around the water collecting pipe 2, and is preferably different from the separation membrane 3. It is preferable that the compression elastic modulus of the permeation | transmission side channel material 5 is 0.1GPa-5GPa. If the elastic modulus is within this range, the permeate-side channel material 5 can be easily wound around the water collecting pipe 2. Specifically, polyester, polyethylene, polypropylene and the like are preferably used.

The elastic modulus of the permeate-side channel material 5 can be measured, for example, by performing a compression test using a precision universal testing machine and creating a stress strain diagram.
(6) Water collecting pipe The water collecting pipe 2 is not particularly limited as long as the water collecting pipe 2 is configured to allow permeate to flow therethrough. As the water collecting pipe 2, for example, a cylindrical member having a side surface provided with a plurality of holes is used.
(7) Water treatment system The separation membrane element described above can be combined with a pump for supplying fluid thereto, a device for pretreating the fluid, or the like to constitute a fluid separation device, such as an RO water purifier. It can be applied to water treatment system.

  The separation membrane element described above can be preferably used when the TDS concentration of raw water is in the range of 10 mg / L to 20,000 mg / L. When raw water having a high TDS concentration range above the above range is used, the osmotic pressure in the latter half of the separation membrane element when operating at a high recovery rate is remarkably increased, and the performance of the separation membrane element is degraded. More preferably, it is 10 mg / L to 5,000 mg / L, more preferably 10 mg / L to 2,000 mg / L.

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.
(The closing rate of the supply water discharge side end face and the supply water supply side end face)
The closing rate of the discharge-side end surface of the feed water was calculated by flowing the methyl violet 500 ppm aqueous solution as the raw water after the evaluation, photographing from the end surface of the wound body, and calculating the ratio of the stained membrane by image analysis.
(Net tilt angle)
The inclination angle of the net was calculated by disassembling the separation membrane element, shooting from above with the net installed on the surface of the separation membrane, and calculating the angle formed by the net constituent yarn and the longitudinal direction of the central tube through image analysis. .
(Projected area ratio between the permeate-side channel material and the separation membrane surface contact part)
The contact part between the permeate-side channel material and the separation membrane surface disassembles the separation membrane element after operation, and images the trace formed on the separation membrane surface using a microscope and transmits the portion where the trace is formed. A contact portion between the side channel material and the separation membrane surface was used. The area was calculated by image analysis, and the ratio of the area of the trace on the separation membrane surface to the unit lattice area of the net was defined as the ratio of the projected area of the permeation-side channel material and the separation membrane surface contact portion.
(Ratio between the maximum value and minimum value of the cross-sectional diameter of the net component yarn)
The ratio between the maximum value and the minimum value of the cross-sectional diameter of the net component yarn is measured with a microscope from above when the component yarn of the net is placed on a flat surface, and the yarn diameter is measured from image analysis every 10 μm. The ratio of values was measured.
(Transverse area ratio of permeate side channel material)
When the permeation-side channel material was loaded with the separation membrane element, the permeation-side channel material was cut along the direction parallel to the longitudinal direction of the water collecting pipe so as to pass through the convex portion of the permeation-side channel material. About the cross section, using the high-precision shape measurement system KS-1100 manufactured by Keyence Corporation, the convex portion relative to the product of the distance between the center of the convex portion measured and the center of the adjacent convex portion and the height of the permeate-side channel material. The ratio of the cross-sectional area of the permeate-side channel material between the center and the center of the adjacent convex portion was calculated, and the average value at any 30 locations was taken as the cross-sectional area ratio.
(Water production)
For the separation membrane element, a NaCl aqueous solution with a concentration of 200 ppm and pH 7.0 was used as the feed water, and the sample was sampled for 1 minute after operating for 60 minutes under the conditions of an operating pressure of 0.41 MPa and a temperature of 25 ° C. Expressed as / min.
(Recovery rate)
In the measurement of the amount of water produced, the ratio of the flow rate of supplied water and the amount of permeated water supplied at a predetermined time was taken as the recovery rate.
(Removal rate (TDS removal rate))
For the feed water and the sampled permeate used in the operation for 1 minute in measuring the amount of water produced, the TDS concentration was determined by conductivity measurement, and the TDS removal rate was calculated from the following formula.

TDS removal rate (%) = 100 × {1− (TDS concentration in permeated water / TDS concentration in feed water)}
Example 1
A 15.2% by weight DMF solution of polysulfone on a non-woven fabric made of polyethylene terephthalate fibers (yarn diameter: 1 dtex, thickness: about 0.09 mm, density 0.80 g / cm ³ ) at a thickness of 180 μm at room temperature (25 ° C.) And immediately immersed in pure water for 5 minutes and immersed in warm water at 80 ° C. for 1 minute to prepare a porous support layer (thickness 0.13 mm) composed of a fiber-reinforced polysulfone support membrane.

  Thereafter, the porous support layer roll is unwound and immersed in a 3.8% by weight aqueous solution of m-PDA for 2 minutes. The support film is slowly pulled up in the vertical direction, and nitrogen is blown from an air nozzle to remove excess from the surface of the support film. After removing the aqueous solution, an n-decane solution containing 0.175% by weight of trimesic acid chloride was applied so that the surface was completely wetted and allowed to stand for 1 minute. Next, in order to remove excess solution from the membrane, the membrane was held vertically for 1 minute and drained. Thereafter, a separation membrane roll washed with hot water at 90 ° C. for 2 minutes was obtained.

  The separation membrane thus obtained is folded and cut so that the effective area of the separation membrane element is 0.4 m 2, and the net (thickness 0.5 mm, pitch: 2.2 mm × 2.2 mm) is supplied to the supply side flow path. One leaf was produced as a material.

  The permeate side channel material is the length of the water collecting tube when the separation membrane element is used while adjusting the temperature of the backup roll to 20 ° C. using an applicator loaded with a comb-shaped shim having a slit width of 0.5 mm and a pitch of 0.9 mm. Highly crystalline PP (MFR 1000 g / 10 min) in a straight line 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 when the envelope film is perpendicular to the direction. , Melting point 161 ° C.) composition pellets comprising 60% by mass and low crystalline α-olefin polymer (Idemitsu Kosan Co., Ltd .; low stereoregular polypropylene “L-MODU · S400” (trade name)) 40% by mass. It was produced by applying a linear temperature on a nonwoven fabric at a resin 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 grid with a pitch of 5 mm).

  A permeate-side channel material is arranged on the permeate side surface of the obtained leaf, and spirally formed in an ABS (acrylonitrile-butadiene-styrene) water collecting pipe (width: 350 mm, diameter: 18 mm, number of holes: 10 × 1 linear line) Wound around. After performing edge cutting at both ends of the wound body, a cap with the outer peripheral portion 50% closed was attached to the supply water discharge end face to produce a separation membrane element having a diameter of 2 inches.

  When the separation membrane element was put in a pressure vessel and each performance was evaluated under the above conditions at a recovery rate of 80%, the results were as shown in Table 1.

(Examples 2 to 12)
A separation membrane element was produced in the same manner as in Example 1 except that the closing portion and closing rate of the feed water discharge end face were changed as shown in Table 1, and performance was evaluated. The results are shown in Table 1.
(Example 13)
A separation membrane element was produced in the same manner as in Example 1 except that a cap with the inner peripheral portion 50% closed was also attached to the supply water supply end face, and performance was evaluated. The results are shown in Table 2.

(Examples 14 to 24)
A separation membrane element was produced in the same manner as in Example 1 except that the closing portion and closing rate of the feed water supply end face and the closing portion and closing rate of the feed water discharge end face were changed as shown in Table 2, and performance was evaluated. . The results are shown in Table 2.
(Example 25)
A separation membrane element was prepared in the same manner as in Example 1 except that a cap with the inner peripheral portion 30% closed was also attached to the supply water supply end face, and performance was evaluated. The results are shown in Table 3.

(Examples 26 to 36)
A separation membrane element was produced in the same manner as in Example 1 except that the closing portion and closing rate of the feed water supply end face and the closing portion and closing rate of the feed water discharge end face were changed as shown in Table 3, and performance was evaluated. . The results are shown in Table 3.
(Example 37)
A separation membrane element was prepared in the same manner as in Example 1 of Example 1 except that the inclination angle of the net that was the supply-side channel material was changed as shown in Table 4, and the performance was evaluated. The results are shown in Table 4.

(Example 38)
Separation is performed in the same manner as in Example 1 except that the projected area ratio of the separation membrane contact portion is changed as shown in Table 4 by using a material having a more elliptical cross-sectional shape as the supply side flow path material. Membrane elements were fabricated and performance was evaluated. The results are shown in Table 4.
(Examples 39 and 40)
Use a net with a different rate of change in diameter in the length direction with the net configuration that is the supply-side channel material,
A separation membrane element was produced in the same manner as in Example 1 except that the ratio between the maximum value and the minimum value of the net component yarn cross-sectional diameter was changed as shown in Table 4, and the performance was evaluated. The results are shown in Table 4.
(Examples 41 and 42)
A separation membrane element was produced in the same manner as in Example 1 except that the cross-sectional area ratio of the permeate-side channel material was changed as shown in Table 4, and performance was evaluated. The results are shown in Table 4.
(Comparative Example 1)
A separation membrane element was produced in the same manner as in Example 1 except that no cap was provided on the supply water discharge end face, and the performance was evaluated. The results are shown in Table 5.

(Comparative Examples 2-7)
A separation membrane element was produced in the same manner as in Example 1 except that the closing portion and closing rate of the feed water discharge end face were changed as shown in Table 5, and performance was evaluated. The results are shown in Table 5.
As is clear from the results shown in Tables 1 to 5, the separation membrane elements of Examples 1 to 42 of the present invention obtain a sufficient amount of permeate having high removal performance even when operated at a high recovery rate. I can say that.
(Comparative Example 8)
A separation membrane element was prepared in the same manner as in Example 1 except that the permeation side channel material was changed as shown in Table 5 in the cross-sectional area ratio, and the performance was evaluated. The results are shown in Table 4.

DESCRIPTION OF SYMBOLS 1 Separation membrane element 2 Water collection pipe 21 Water collection hole 3 Separation membrane 4 Supply side flow path material 5 Permeation side flow path material 6 Membrane unit 61 Rolling body 71, 72 Telescope prevention plate 8 Supply water flow path closing part 101 Supply fluid 102 Permeating fluid 103 Concentrated fluid

Claims (20)

A separation membrane having a supply-side surface and a permeate-side surface, and disposed such that the permeate-side surfaces face each other;
A supply-side flow path material provided between the supply-side surfaces of the separation membrane;
A permeation-side channel material provided between the permeation-side surfaces of the separation membrane,
A wound body is formed by winding the separation membrane, the supply-side channel material, and the permeation-side channel material around a perforated central tube,
Raw water is supplied from one end face of the wound body in the longitudinal direction of the perforated central tube,
Discharged from the other end surface of the wound body,
The channel closing rate of the supply-side channel on the other end surface is 35 to 95%.
Separation membrane element. In the other end surface, the flow path of the supply side flow path is continuously closed from the outermost side to the inner side in the winding direction.
The separation membrane element according to claim 1. In the other end surface, the flow path of the supply side flow path is continuously closed from the innermost side to the outer side in the winding direction.
The separation membrane element according to claim 1. In the other end surface, the flow path of the supply side flow path is intermittently closed in the winding direction.
The separation membrane element according to claim 1. The length of the closed part (closed part) is 1 to 100 mm,
The separation membrane element according to claim 4. The length of one part (non-closed part) other than the closed part (closed part) on the other end surface is 1 to 100 mm.
The separation membrane element according to claim 4. The channel closing rate of the one end face is 50 to 90%,
The separation membrane element according to claim 1. In the one end face, the mouth is continuously closed from the outermost side to the inner side in the winding direction.
The separation membrane element according to claim 7. In the one end face, the mouth is continuously closed from the innermost side to the outer side in the winding direction.
The separation membrane element according to claim 7. The one end face is intermittently closed in the winding direction.
The separation membrane element according to claim 7. The flow path of the end face is closed by an adhesive,
The separation membrane element according to claim 1. The flow path of the end face is closed by a cap provided on the end face of the wound body,
The separation membrane element according to claim 1. The cross section of the permeate-side channel material has a plurality of channels, and the cross-sectional area ratio is 0.4 or more and 0.75 or less.
The separation membrane element according to claim 1. The supply-side channel material is a net composed of a plurality of yarns, and the inclination angle of the yarns is −60 ° or more and 60 ° or less with respect to the average flow angle of the supply fluid.
The separation membrane element according to claim 1. The contact area between the supply-side channel material and the separation membrane is 0.01 or more and 0.25 or less with respect to the area of the separation membrane.
The separation membrane element according to claim 1. The supply-side channel material is a net composed of a plurality of yarns, and the diameter of the cross section perpendicular to the longitudinal direction of the yarns is such that the diameter of the minimum part / the diameter of the maximum part is 0.1 or more and 0.7 or less is there,
The separation membrane element according to claim 1. The longitudinal length of the perforated central tube of the separation membrane is 50 cm or less,
The separation membrane element according to any one of claims 1 to 16. The length of the separation membrane in the direction perpendicular to the longitudinal direction of the perforated central tube is longer than the length of the perforated central tube in the longitudinal direction;
The separation membrane element according to any one of claims 1 to 16.   The operation method of a separation membrane element which uses the separation membrane element in any one of Claims 1-18, and makes the ratio of the amount of water produced to 35% or more with respect to the amount of water supplied to the said separation membrane element.   The operation method of the separation membrane element according to claim 19, wherein the TDS concentration of the raw water is 10 to 20,000 mg / L or less.

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