JP2016068081A - Separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane element capable of stabilizing a water production amount and a separation removal property when the separation membrane element is operated over a long period of time.SOLUTION: Provided is a separation membrane element comprising: a water catchment pipe; and separation membrane leaves that have a supply side flow passage material and a separation membrane interposing the supply side flow passage material from both sides so that a supply side surface is directed to an inner side, and that are wound around the water catchment pipe in a laminated state. In the separation membrane element, at least the following separation membrane leaves (1) and (2) are comprised and these leaves (1) and (2) are alternately laminated. (1) a separation membrane leaf having a permeation side flow passage material in which resin is fastened on a permeation side surface of the separation membrane. (2) a separation membrane leaf in which resin is not fastened on a permeation side surface of the separation membrane.SELECTED DRAWING: Figure 8

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. The separation membrane used for the separation membrane element is selectively used depending on the target separation component and separation performance.

  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, taking a fluid separation membrane element used for reverse osmosis filtration as an example, the separation membrane element member is a supply-side flow path material that supplies the raw fluid to the separation membrane surface, and a separation that separates components contained in the raw fluid A spiral separation membrane element in which a member made of a permeate-side flow path material for guiding a permeate-side fluid that has permeated the separation membrane and separated from the supply-side fluid to the central tube is wound around the central tube. It is widely used in that pressure is applied to the fluid and a large amount of permeated fluid is taken out.

  As a member of the spiral type reverse osmosis separation membrane element, the supply side flow path material mainly uses a polymer net to form a flow path of the supply side fluid, and the separation membrane has a high cross-linkage such as polyamide. A separation function layer consisting of molecules, a porous support membrane made of a polymer such as polysulfone, and a composite semipermeable membrane in which nonwoven fabrics made of a polymer such as polyethylene terephthalate are laminated from the supply side to the permeation side are used. In the road material, a fabric member called a tricot having a smaller interval than the supply side flow path material is used for the purpose of preventing the film from dropping and forming a flow path on the permeate side.

  In recent years, a high performance of separation membrane elements has been demanded due to an increase in water production cost. In order to improve the separation performance of the separation membrane element and increase the amount of permeated fluid per unit time, it has been proposed to improve the performance of each flow path member and separation membrane. In Patent Document 1, it is proposed to use a flat membrane having a hollow passage inside by forming irregularities on the surface on the supply side without using a base material. In Patent Document 2, it is proposed to use a sheet-like material formed with unevenness as a permeate-side channel material.

JP-A-11-114381 JP 2006-247453 A

  However, the separation membrane element described above cannot be said to have sufficient element performance stability when operated for a long period of time.

  Accordingly, an object of the present invention is to provide a separation membrane element that can stabilize the amount of water produced and separation / removability particularly when the separation membrane element is operated for a long period of time.

In order to achieve the above object, the present invention comprises the following configurations (1) to (4).
(1) A water collecting pipe, a supply side flow path material, and a separation membrane that sandwiches the supply side flow path material from both sides so that the supply side surface faces inward, and is laminated around the water collection pipe A separated separation membrane element, wherein the separation membrane element includes at least the following separation membrane leaf of <1><2>, and the <1><2> A separation membrane element, wherein separation membrane leaves are alternately laminated.
<1> Having a permeate-side channel material with a resin fixed on the permeate side surface of the separation membrane <2> With no resin fixed on the permeate side surface of the separation membrane (2) <1> The separation membrane element according to (1), wherein the variation coefficient of the water production amount of the separation membrane leaf of <2> is 15% or less and the variation coefficient of the removal rate is 15% or less.
(3) The variation coefficient of the water production amount of the separation membrane leaf of <1> and <2> is 10% or less, and the variation coefficient of the removal rate is 10% or less, (1) or (2) Separation membrane element.
(4) The permeation-side channel material has a length in the length direction of the separation membrane that is greater than a length in the width direction perpendicular to the length direction, and is arranged at intervals in the width direction. The separation membrane element according to any one of (1) to (3), wherein, in a cross section perpendicular to the length direction, at least a part of a circumference not fixed to the separation membrane is rounded. .

  According to the present invention, it is possible to provide a separation membrane element capable of stabilizing the amount of water produced and separation / removability even when the separation membrane element is operated for a long period of time.

The top view which shows a separation membrane provided with the flow-path material provided continuously in the length direction of the separation membrane. The top view which shows a separation membrane provided with the flow-path material provided discontinuously in the length direction of the separation membrane. Sectional drawing of the separation membrane of FIG. 1 and FIG. Sectional drawing of the separation membrane of FIG. 1 and FIG. Sectional drawing which shows schematic structure of a separation membrane main body. The expansion | deployment perspective view which shows one form of a separation membrane element. The expansion | deployment perspective view which shows one form of a separation membrane element. The schematic diagram which shows one form before film | membrane leaf winding.

Hereinafter, an embodiment of the present invention will be described in detail.
[1. Separation membrane)
(1-1) Overview of Separation Membrane A separation membrane is a membrane that can separate components in a fluid supplied to the surface of the separation membrane and obtain a permeated fluid that has permeated the separation membrane. The separation membrane referred to in the present specification can include those in which a resin or the like is disposed so as to form a flow path. Also, a conventional membrane that cannot form a flow path and exhibits only a separation function is called a separation membrane body.

  In this document, the “supply side surface” means the surface on the separation functional layer side of the separation membrane. The “transmission side surface” means the opposite side surface, that is, the substrate side surface.

  As will be described later, when the separation membrane body includes a base material 201, a porous support layer 202, and a separation function layer 203 as shown in FIG. 5, generally, the surface on the separation function layer 203 side is on the supply side. The surface 21 and the surface on the base material 201 side are the surface 22 on the transmission side.

  In FIG. 5, the separation membrane body 2 is described as a laminate of a base material 201, a porous support layer 202 and a separation functional layer 203. As described above, the surface opened outside the separation functional layer 203 is the supply-side surface 21, and the surface opened outside the base material 201 is the transmission-side surface 22.

The x-axis, y-axis, and z-axis direction axes are shown in the figure. As shown in FIG. 1 and the like, the separation membrane body 2 is rectangular, and the x-axis direction and the y-axis direction are parallel to the outer edge of the separation membrane body 2. The x direction corresponds to the width direction of the separation membrane, and the y axis direction corresponds to the length direction. From the viewpoint of the direction during film formation, the width direction may be referred to as CD (Cross direction) and the length direction may be referred to as MD (Machine direction).
(1-2) Separation membrane body <Overview>
As the separation membrane body, a membrane having separation performance according to the method of use, purpose and the like is used. The separation membrane body may be formed of a single layer or a composite membrane including a separation functional layer and a substrate. As shown in FIG. 5, in the composite membrane, a porous support layer 202 may be formed between the separation functional layer 203 and the base material 201.

<Separation function layer>
The thickness of the separation functional layer is not limited to a specific numerical value, but is preferably 5 nm or more and 3000 nm or less in terms of separation performance and transmission performance. In particular, in the case of a reverse osmosis membrane, a forward osmosis membrane, and a nanofiltration membrane, the thickness is preferably 5 nm or more and 300 nm or less.

  The thickness of the separation functional layer can be based on the conventional method for measuring the thickness of the separation membrane. For example, the separation membrane is embedded with resin, and an ultrathin section is prepared by cutting the separation membrane, and the obtained section is subjected to processing such as staining. Thereafter, the thickness can be measured by observing with a transmission electron microscope. Further, when the separation functional layer has a pleat structure, measurement can be made at intervals of 50 nm in the cross-sectional length direction of the pleat structure located above the porous support layer, the number of pleats can be measured, and the average can be obtained. it can.

  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 cellulose, polyvinylidene fluoride, polyether sulfone, or polysulfone as a main component is preferably applied as the separation functional layer.

  In this document, “X contains Y as a main component” means that the Y content in X is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass. % Or more, more preferably 90% by mass or more, and most preferably 95% by mass or more. In addition, when there are a plurality of components corresponding to Y, the total amount of these components only needs to satisfy the above range.

  On the other hand, as the separation functional layer provided with the porous support layer, a crosslinked polymer is preferably used in terms of easy pore diameter control 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, and the like are preferably used in terms of excellent separation performance of components in raw water. 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 is formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide by a known method. For example, by applying a polyfunctional amine aqueous solution to the porous support layer, removing the excess amine aqueous solution with an air knife or the like, and then applying an organic solvent solution containing a polyfunctional acid halide, the polyamide separation functional layer Is obtained.

  Further, the constituent component of the separation functional layer is not limited to polyamide, and may be an organic-inorganic hybrid having Si element or the like.

  For any separation functional layer, the surface of the membrane may be hydrophilized with an alcohol-containing aqueous solution or an alkaline aqueous solution, for example, before use.

<Porous support layer>
The porous support layer is a layer that supports the separation functional layer, and is also referred to as a porous resin layer.

  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 gives mechanical strength to the separation membrane, and does not have separation performance like a separation membrane for components having a small molecular size such as ions. The pore size and pore distribution of the porous support layer are not particularly limited. For example, the porous support layer may have uniform and fine pores, or the side on which the separation functional layer is formed. It may have a pore size distribution such that the diameter gradually increases from the surface to the other surface. In any case, the projected area equivalent circle diameter of the pores measured using an atomic force microscope or an electron microscope on the surface on the side where the separation functional layer is formed is 1 nm or more and 100 nm or less. preferable. Particularly in terms of interfacial polymerization reactivity and retention of the separation functional layer, the pores on the surface on the side where the separation functional layer is formed in the porous support layer preferably have a projected area equivalent circle diameter of 3 nm to 50 nm. .

  The thickness of the porous support layer is not particularly limited, but is preferably in the range of 20 μm to 500 μm, more preferably 30 μm to 300 μm, for reasons such as giving strength to the separation membrane.

  The form of the porous support layer can be observed with a scanning electron microscope, a transmission electron microscope, or an atomic force microscope. For example, when observing with a scanning electron microscope, after peeling off the porous support layer from the substrate, it is cut by the freeze cleaving method to obtain a sample for cross-sectional observation. The sample is thinly coated with platinum, platinum-palladium, or ruthenium tetrachloride, preferably ruthenium tetrachloride, and observed with a high-resolution field emission scanning electron microscope (UHR-FE-SEM) at an acceleration voltage of 3 kV to 6 kV. As the high-resolution field emission scanning electron microscope, an S-900 electron microscope manufactured by Hitachi, Ltd. can be used. Based on the obtained electron micrograph, the film thickness of the porous support layer and the projected area equivalent circle diameter of the surface can be measured.

  The thickness and pore diameter of the porous support layer are average values, and the thickness of the porous support layer is measured at intervals of 20 μm in a direction perpendicular to the thickness direction by cross-sectional observation, and is an average value of 20 points. Moreover, a hole diameter is an average value of each projected area circle equivalent diameter measured about 200 holes.

  Next, a method for forming the porous support layer will be described. For example, the porous support layer is prepared by pouring an N, N-dimethylformamide (hereinafter referred to as DMF) solution of the above polysulfone into a constant thickness on a substrate to be described later, for example, a densely woven polyester cloth or non-woven cloth. It can be produced by molding and wet coagulating it 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.

  For example, a predetermined amount of polysulfone is dissolved in DMF to prepare a polysulfone resin solution having a predetermined concentration. Next, this polysulfone resin solution is applied to a substrate made of polyester cloth or nonwoven fabric to a substantially constant thickness, and after removing the surface solvent in the air for a certain period of time, the polysulfone is coagulated in the coagulation liquid. Can be obtained.

<Base material>
From the viewpoint of the strength and dimensional stability of the separation membrane body, the separation membrane body may have a substrate. As the base material, it is preferable to use a fibrous base material in terms of strength, unevenness forming ability and fluid permeability.

  As a base material, both a long fiber nonwoven fabric and a short fiber nonwoven fabric can be used preferably. In particular, since the long fiber nonwoven fabric has excellent film-forming properties, when the polymer solution is cast, the solution penetrates through the permeation, the porous support layer peels off, and Is preferable because it can prevent the film from becoming non-uniform due to fluffing of the substrate and the like, and the occurrence of defects such as pinholes. In addition, since the base material is made of a long-fiber non-woven fabric composed of thermoplastic continuous filaments, it suppresses non-uniformity and membrane defects during casting of a polymer solution caused by fuzz that occurs when a short-fiber non-woven fabric is used. be able to. Furthermore, since the separation membrane is tensioned in the film-forming direction when continuously formed, it is preferable to use a long-fiber nonwoven fabric having excellent dimensional stability as a base material.

  In the long-fiber nonwoven fabric, in terms of moldability and strength, it is preferable that the fibers in the surface layer on the side opposite to the porous support layer have a longitudinal orientation than the fibers in the surface layer on the porous support layer side. According to such a structure, not only a high effect of preventing membrane breakage by maintaining strength is realized, but also a laminate comprising a porous support layer and a substrate when imparting irregularities to the separation membrane The moldability is improved, and the uneven shape on the surface of the separation membrane is stabilized, which is preferable.

  More specifically, the fiber orientation degree in the surface layer on the side opposite to the porous support layer of the long-fiber nonwoven fabric is preferably 0 ° or more and 25 ° or less, and the fiber orientation in the surface layer on the porous support layer side. The degree of orientation difference with respect to the degree is preferably 10 ° or more and 90 ° or less.

  The separation membrane manufacturing process and the element manufacturing process include a heating process, but a phenomenon occurs in which the porous support layer or the separation functional layer contracts due to the heating. In particular, the shrinkage is remarkable in the width direction where no tension is applied in continuous film formation. Since shrinkage causes problems in dimensional stability and the like, a substrate having a small rate of thermal dimensional change is desired. In the nonwoven fabric, when the difference between the fiber orientation degree on the surface layer opposite to the porous support layer and the fiber orientation degree on the porous support layer side surface layer is 10 ° or more and 90 ° or less, the change in the width direction due to heat is suppressed. Can also be preferred.

  Here, the fiber orientation degree is an index indicating the direction of the fibers of the nonwoven fabric substrate constituting the porous support layer. Specifically, the fiber orientation degree is the film forming direction (MD) when performing continuous film formation, that is, the angle between the longitudinal direction of the nonwoven fabric substrate and the longitudinal direction of the fibers constituting the nonwoven fabric substrate. Average value. That is, if the longitudinal direction of the fiber is parallel to the film forming direction, the fiber orientation degree is 0 °. If the longitudinal direction of the fiber is perpendicular to the film forming direction, that is, if it is parallel to the width direction of the nonwoven fabric substrate, the degree of orientation of the fiber is 90 °. Accordingly, the closer to 0 ° the fiber orientation, the longer the orientation, and the closer to 90 °, the lateral orientation.

  The degree of fiber orientation is measured as follows. First, 10 small piece samples are randomly collected from the nonwoven fabric. Next, the surface of the sample is photographed at 100 to 1000 times with a scanning electron microscope. In the photographed image, 10 fibers are selected for each sample, and the angle of the fibers in the longitudinal direction when the longitudinal direction of the nonwoven fabric is 0 ° is measured. Here, the longitudinal direction of the nonwoven fabric refers to “Machine direction” at the time of manufacturing the nonwoven fabric. The longitudinal direction of the nonwoven fabric coincides with the film forming direction of the porous support layer. These directions coincide with the length direction (y direction) in the figure. The x direction in the figure is the width direction of the nonwoven fabric, and corresponds to “Cross direction” at the time of manufacturing the nonwoven fabric. In this way, the angle is measured for a total of 100 fibers per nonwoven fabric. The average value is calculated from the angles in the longitudinal direction for the 100 fibers thus measured. The value obtained by rounding off the first decimal place of the obtained average value is the fiber orientation degree.

The thickness of the substrate is preferably in the range of 30 μm to 300 μm, and more preferably in the range of 50 μm to 250 μm.
(1-3) Permeation side channel material <Overview>
As shown in FIGS. 1 to 4, a plurality of permeation-side flow path materials (flow-path materials) are formed on the permeation-side surface 22 of the separation membrane body 2 constituting the separation membrane 1 so as to form a permeation-side flow path 5. ) 3 is provided.

  “Provided to form a flow path on the permeate side” means that the permeated fluid that has permeated through the main body of the separation membrane can reach the water collecting pipe when the separation membrane is incorporated in a separation membrane element described later. It means that the road material is formed. Details of the configuration of the channel material are as follows.

<Constituent components of channel material>
The flow path member 3 is preferably formed of a material different from that of the separation membrane body 2. The different material means a material having a composition different from that of the material used in the separation membrane body 2. In particular, the composition of the flow path material 3 is preferably different from the composition of the surface of the separation membrane body 2 on which the flow path material 3 is formed, that is, the surface on the permeate side. It is preferable that the composition of the layer is also different.

Although it does not specifically limit as a material which comprises a flow-path material, Resin is used preferably. Specifically, from the viewpoint of chemical resistance, ethylene vinyl acetate copolymer resins, polyolefins such as polyethylene and polypropylene, and olefin copolymers are preferable, and polymers such as urethane resins and epoxy resins can also be selected. Or it can use as a mixture which consists of two or more types. In particular, since a thermoplastic resin is easy to mold, a channel material having a uniform shape can be formed. <Flow channel material shape and arrangement>
<< Overview >>
The permeate-side channel material forms a plurality of channels (for example, grooves) for guiding the fluid (permeated water) that has passed through the separation membrane main body to a water collecting pipe described later. For reasons that will be described later, the flow resistance can be remarkably reduced by arranging the permeate-side flow path material directly fixed to the permeate-side surface of the separation membrane body.

  A tricot that has been widely used in the past is a knitted fabric, and is composed of three-dimensionally intersecting yarns. That is, the tricot has a two-dimensionally continuous structure. When such a tricot is applied as a channel material, the height of the channel is smaller than the thickness of the tricot. That is, the entire thickness of the tricot cannot be used as the height of the flow path.

  On the other hand, as an example of the configuration of the present invention, the flow path members 3 shown in FIG. 1 and the like are arranged so as not to overlap each other. Therefore, the height (that is, the thickness) of the flow path member 3 of this embodiment is all utilized as the height of the groove of the flow path of the permeated water (permeation side flow path) that has passed through the separation membrane body. Therefore, when the flow path material 3 of the present embodiment is applied, the flow path becomes higher than when a tricot having the same thickness as the height of the flow path material 3 is applied. That is, since the cross-sectional area of the flow path becomes larger, the flow resistance becomes smaller.

  By providing a plurality of discontinuous flow path members 3, the separation membrane 1 can suppress the pressure loss when incorporated in the separation membrane element 100 described later. As an example of such a configuration, in FIG. 1, the flow path material 3 is formed discontinuously only in the width direction, and in FIG. 2, it is formed discontinuously in both the width direction and the length direction. In FIG. 1 and FIG. 2, a permeate flow path 5 is formed between adjacent flow path materials 3.

  The separation membrane is preferably disposed so that the length direction of the separation membrane element coincides with the winding direction. That is, in the separation membrane element, the separation membrane is preferably arranged so that the width direction is parallel to the longitudinal direction of the water collecting pipe 6 and the length direction is orthogonal to the longitudinal direction of the water collecting pipe 6.

  In the example shown in FIG. 1, the flow path material 3 is provided discontinuously in the width direction, and is provided so as to be continuous from one end to the other end of the separation membrane body 2 in the length direction. That is, when the separation membrane is incorporated into the separation membrane element, the flow path material 3 is arranged so as to continue from the inner end to the outer end of the separation membrane 1 in the winding direction. The inner side in the winding direction is the side close to the water collecting pipe in the separation membrane, and the outer side in the winding direction is the side far from the water collecting pipe in the separation membrane. In the present invention, the phrase “the channel material is continuous in the length direction” means that the channel material 3 is provided without interruption as shown in FIG. Although there are places where the flow is interrupted, it includes both cases where the flow path material 3 is substantially continuous. The “substantially continuous” form preferably satisfies that the distance e between the flow path materials in the length direction (that is, the distance between the flow path materials in the longitudinal direction) is 5 mm or less. In particular, the distance e is more preferably 1 mm or less, and further preferably 0.5 mm or less. In addition, the total value of the intervals e included from the beginning to the end of the one row of flow path materials arranged in the length direction is preferably 100 mm or less, more preferably 30 mm or less, and more preferably 3 mm or less. Further preferred. In the form of FIG. 2, the interval e is 0 (zero).

  When the flow path material 3 is provided without interruption as shown in FIG. 1, membrane dropping is suppressed during pressure filtration. Membrane sagging is that the membrane falls into the channel and narrows the channel.

  In FIG. 2, the flow path material 3 is discontinuously provided not only in the width direction but also in the length direction. That is, the channel material 3 is provided at intervals in the length direction. However, as described above, since the flow path member 3 is substantially continuous in the length direction, the film sagging is suppressed. In addition, by providing the discontinuous flow path material 3 in the two directions as described above, the contact area between the flow path material and the fluid is reduced, so that the pressure loss is reduced. In other words, this form is a configuration in which the flow path 5 includes a branch point. That is, in the configuration of FIG. 3, the permeating fluid is divided by the flow path material 3 while flowing through the flow path 5, and can further merge downstream.

  As described above, in FIG. 1, the flow path material 3 is provided so as to be continuous from one end to the other end of the separation membrane body 2 in the length direction. In FIG. 2, the flow path material 3 is divided into a plurality of portions in the length direction, but these plurality of portions are provided so as to be arranged from one end to the other end of the separation membrane body 2.

  The channel material is “provided from one end to the other end of the separation membrane body” means that the channel material is provided up to the edge of the separation membrane body 2 and the channel material is provided in the vicinity of the edge. Includes both forms with no areas.

  That is, the flow path material only needs to be distributed over the entire separation membrane main body 2 in the length direction to the extent that a permeate-side flow path can be formed, and the flow path material is not provided in the separation membrane main body. There may be parts. For example, the flow path material does not need to be provided in the sealing portion with the other separation membrane on the permeate side surface. Moreover, the area | region where a flow-path material is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on the other specification or manufacture.

  Also in the width direction, the flow path material 3 can be distributed substantially uniformly over the entire separation membrane body 2. However, like the distribution in the length direction, the flow path material does not need to be provided in the sealing portion with the other separation membrane on the permeate side surface. Moreover, the area | region where a flow-path material is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on the other specification or manufacture.

<< Dimensions of separation membrane body and flow path material >>
As shown in FIGS. 1 to 3, a to f indicate the following values.

a: Length of the separation membrane body 2 b: Distance between the flow path members 3 in the width direction of the separation membrane body 2 c: Height of the flow path materials (the flow path material 3 and the permeation side surface 22 of the separation membrane body 2 Difference in height)
d: width of the channel material 3 e: interval of the channel material in the length direction of the separation membrane body 2 f: length of the channel material 3 For measurement of the values a to f, for example, a commercially available shape measurement system Alternatively, a microscope or the like can be used. Each value is obtained by performing measurement at 30 or more locations on one separation membrane, and calculating an average value by dividing the sum of these values by the number of measurement total locations. Thus, each value obtained as a result of the measurement at at least 30 locations only needs to satisfy the above range.

(Length of separation membrane body a)
The length a is the distance from one end of the separation membrane body 2 to the other end in the length direction. When this distance is not constant, the length a can be obtained by measuring this distance at 30 or more positions in one separation membrane body 2 and obtaining an average value.

(Channel material interval b in the width direction)
The interval b between the flow path members 3 in the width direction corresponds to the width of the flow path 5. When the width of one flow path 5 is not constant in one cross section, that is, when the side surfaces of two adjacent flow path materials 3 are not parallel, the maximum width of one flow path 5 within one cross section The average value of the minimum values is measured, and the average value is calculated. As shown in FIG. 6, in the cross section perpendicular to the length direction, when the channel material 3 has a trapezoidal shape with a thin top and a thick bottom, first, the distance between the upper portions of the two adjacent channel materials 3 Measure the distance between the lower parts and calculate the average value. The distance between the flow path members 3 is measured in any 30 or more cross sections, and an average value is calculated in each cross section. And the space | interval b is calculated by calculating further the arithmetic mean value of the average value obtained in this way.

  As the distance b increases, the pressure loss decreases, but the film falls easily. Conversely, the smaller the distance b, the less likely the film will drop, but the greater the pressure loss. Considering the pressure loss, the interval b is preferably 0.05 mm or more, more preferably 0.2 mm or more, and further preferably 0.3 mm or more. Further, in terms of suppression of film sagging, the interval b is preferably 5 mm or less, more preferably 3 mm or less, still more preferably 2 mm or less, and particularly preferably 0.8 mm or less.

  These upper and lower limits can be combined arbitrarily. For example, the interval b is preferably 0.2 mm or more and 5 mm or less, and within this range, the pressure loss can be reduced while suppressing the film sagging. The distance b is more preferably 0.05 mm or more and 3 mm or less, 0.2 mm or more and 2 mm or less, and further preferably 0.3 mm or more and 0.8 mm or less.

(Height c of channel material)
The height c is a difference in height between the flow path member 3 and the surface of the separation membrane main body 2. As shown in FIG. 3, the height c is a difference in height between the highest portion of the flow path material 3 and the permeation side surface of the separation membrane main body in a cross section perpendicular to the length direction. That is, in the height, the thickness of the portion impregnated in the base material is not considered. The height c is a value obtained by measuring and averaging the heights of the flow path materials 3 at 30 or more locations. The height c of the flow path material may be obtained by observing a cross section of the flow path material in the same plane, or may be obtained by observing cross sections of the flow path material in a plurality of planes.

  The height c can be appropriately selected according to the use condition and purpose of the element, but may be set as follows, for example.

  The larger the height c, the smaller the flow resistance. Therefore, the height c is preferably 0.03 mm or more, more preferably 0.05 mm or more, and still more preferably 0.1 mm or more. On the other hand, the smaller the height c, the larger the number of films filled per element. Therefore, the height c is preferably 0.8 mm or less, more preferably 0.4 mm or less, and still more preferably 0.32 mm or less. These upper and lower limits can be combined. For example, the height c is preferably 0.03 mm or more and 0.8 mm or less, more preferably 0.05 mm or more and 0.4 mm or less, and 0.1 mm More preferably, it is 0.32 mm or less.

  Moreover, it is preferable that the difference in height between two adjacent channel materials is small. If the difference in height is large, the separation membrane is distorted during pressure filtration, so that defects may occur in the separation membrane. The difference in height between two adjacent channel materials is preferably 0.1 mm or less, more preferably 0.06 mm or less, and further preferably 0.04 mm or less.

  For the same reason, the maximum height difference of all the flow path materials provided in the separation membrane is preferably 0.25 mm or less, more preferably 0.1 mm or less, and further preferably 0.03 mm or less. .

(Width d of the channel material)
The width d of the flow path material 3 is measured as follows. First, in one cross section perpendicular to the length direction, the average value of the maximum width and the minimum width of one flow path material 3 is calculated. That is, in the channel material 3 having a thin upper part and a thick lower part as shown in FIG. 3, 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 the arithmetic average thereof, the width d per film can be calculated.

  The width d of the flow path member 3 is preferably 0.2 mm or more, and more preferably 0.3 mm or more. When the width d is 0.2 mm or more, the shape of the flow path material can be maintained even when pressure is applied to the flow path material 3 during operation of the separation membrane element, and the permeation side flow path is stably formed. The The width d is preferably 2 mm or less, and more preferably 1.5 mm or less. When the width d is 2 mm or less, a sufficient flow path on the permeate side can be secured.

  When the width of the channel material is wider than the channel material interval b, the pressure applied to the channel material can be dispersed.

  The channel material 3 is formed such that its length is larger than its width. Such a long channel material 3 is also referred to as a “wall-like object”.

(Channel material interval e in the length direction)
The distance e between the flow path members 3 in the length direction is the shortest distance between the flow path members 3 adjacent in the length direction. As shown in FIG. 1, the flow path material 3 is continuous from one end to the other end of the separation membrane body 2 in the length direction (in the separation membrane element, from the inner end to the outer end in the winding direction). When provided, the interval e is 0 mm. In addition, as shown in FIG. 2, when the flow path material 3 is discontinuous in the length direction, the interval e is preferably 5 mm or less, more preferably 1 mm or less, and further preferably 0.5 mm or less. It is. When the distance e is within the above range, the mechanical load on the film is small even when the film is dropped, and the pressure loss due to the blockage of the flow path can be relatively small. In addition, the minimum of the space | interval e is 0 mm.

(Length f of channel material)
The length f of the flow path material 3 is the length of the flow path material 3 in the length direction of the separation membrane body 2. The length f is obtained by measuring the length of 30 or more flow path members 3 in one separation membrane 1 and calculating the average value. The length f of the channel material may be equal to or less than the length a of the separation membrane body. When the length f of the flow path material is equal to the length a of the separation membrane body, the flow path material 3 is continuously provided from the inner end to the outer end in the winding direction of the separation membrane 1. Point to. The length f is preferably 10 mm or more, more preferably 20 mm or more. Since the length f is 10 mm or more, the flow path is secured even under pressure.

(Shape of channel material)
In the embodiment of the present invention, it is preferable that the cross-sectional shape of the permeation-side channel material in the width direction is rounded at least at a part of the periphery of the portion not fixed to the separation membrane body 2. As a shape in the cross-sectional width direction of the flow path material 3, when the separation membrane element is made round by rounding at least a part of the circumference not in contact with the membrane surface, The quality of the permeate can be stably maintained without damaging the membrane. Specific examples of such preferable cross-sectional shapes include (a) semicircular shape, (b) semielliptical shape, (c) rounded rectangular shape, and (d) rounded round trapezoid shape as shown in FIG. Here, “semicircular” represents a shape in which the cross-sectional circumferential length is π times the length in the cross-sectional width direction, and “semi-elliptical” refers to the circumference of the portion not fixed to the separation membrane body 2. It represents a shape that is at least partially rounded and does not satisfy the above semicircular relational expression. The cross-sectional circumferential length is the circumferential length of the portion not fixed to the separation membrane body 2. Further, the angle R is preferably 0.005 mm or more, more preferably 0.008 mm or more, and further preferably 0.01 mm or more. Furthermore, the angle R is preferably 0.8 mm or less, which is a value smaller than the height of the flow path material, more preferably 0.4 mm or less, and still more preferably 0.32 mm or less.

  If the shape of the channel material 3 in the cross-sectional width direction is a shape that does not have a round shape such as a rectangle or a trapezoid, the contact area between the separation membrane body 2 and the channel material 3 can be increased. The deformation of the flow path material 3 due to the pressure applied to the flow path material can be suppressed, and the interval between the adjacent flow path materials can be reduced. As a result, the drop of the separation membrane body 2 during pressure filtration can be suppressed.

  On the other hand, if the outer shape in the cross-sectional shape is rounded, even if continuous operation is performed for a long time, it is difficult to cause damage to the membrane and element performance due to the damage.

  The cross-sectional shape of the permeation side channel material can be observed and analyzed by using a microscope, image analysis software ImageJ, or the like.

  If the flow path material is a thermoplastic resin, the shape of the flow path material can be freely changed to satisfy the required separation characteristics and permeation performance conditions by changing the processing temperature and the type of thermoplastic resin to be selected. Can be adjusted.

  Further, when the shape of the separation membrane of the flow path material in the planar direction is a straight line, the adjacent flow path materials may be arranged substantially parallel to each other. “Arranged substantially in parallel” means, for example, that the channel material does not intersect on the separation membrane, the angle formed by the longitudinal direction of two adjacent channel materials is 0 ° or more and 30 ° or less, It includes that the angle is from 0 ° to 15 °, and that the angle is from 0 ° to 5 °.

  Further, the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the water collecting pipe is preferably 60 ° or more and 120 ° or less, more preferably 75 ° or more and 105 ° or less, and 85 ° or more and 95 °. More preferably, it is as follows. When the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the water collecting pipe is within the above range, the permeated water is efficiently collected in the water collecting pipe.

  In order to stably form the flow path, it is preferable that the drop of the separation membrane body is suppressed even when the separation membrane body is pressurized during use of the separation membrane element. For this purpose, it is preferable that the contact area between the separation membrane main body and the flow path material is large, that is, the area of the flow path material relative to the area of the separation membrane main body (projected area on the membrane surface of the separation membrane main body) is large. On the other hand, in order to reduce pressure loss, it is preferable that the cross-sectional area of a flow path is wide.

  The shape of the channel material is not limited to the shape illustrated. Change the processing temperature and the type of hot-melt resin to be selected when the flow path material is placed on the permeate side surface of the separation membrane body by, for example, a hot melt method by fixing a molten material. Thus, the shape of the flow path material can be freely adjusted so that the required separation characteristics and permeation performance conditions can be satisfied.

  1 to 3, the shape of the flow path member 3 in the planar direction (the shape in the xy plan view) is a linear shape whose longitudinal direction is parallel to the winding direction. However, the flow path member 3 can be changed to another shape as long as it protrudes from the surface of the separation membrane body 2 and does not impair the desired effect as the separation membrane element. That is, the shape in the plane direction may be a curved line, a wavy line, or the like. In addition, a plurality of flow path materials different in at least one of width and length may be formed on one separation membrane.

(Projected area ratio)
The projected area ratio of the flow path material to the permeation side surface of the separation membrane is 0.03 or more and 0.85 or less, particularly in terms of reducing the flow resistance of the permeation side flow path and forming the flow path stably. Is preferably 0.15 or more and 0.85 or less, more preferably 0.2 or more and 0.75 or less, and further preferably 0.3 or more and 0.6 or less. The projected area ratio is a value obtained by dividing the projected area of the flow path material obtained when the separation membrane is cut out at 5 cm × 5 cm and projected onto a plane parallel to the surface direction of the separation membrane by the cut-out area (25 cm ² ). It is. This value can also be expressed by the equation df / (b + d) (e + f).
[2. Separation membrane element)
(2-1) Overview As shown in FIG. 6, the separation membrane element 100 includes the water collecting pipe 6 and any one of the above-described configurations, and includes the separation membrane 1 wound around the water collecting pipe 6. The separation membrane element 100 further includes end plates 91 and 92 and other members (not shown).
(2-2) Separation membrane The separation membrane 1 is wound around the water collecting pipe 6 and is arranged so that the width direction is along the longitudinal direction of the water collecting pipe 6. As a result, the separation membrane 1 is disposed such that the length direction is along the winding direction.

  Therefore, the permeation-side flow path material 3 that is a wall-like material is discontinuously arranged along the longitudinal direction of the water collecting pipe 6 at least on the permeation-side surface 22 of the separation membrane main body constituting the separation membrane 1. That is, the flow path 5 is formed to be continuous from the outer end to the inner end of the separation membrane in the winding direction. As a result, the permeated water easily reaches the central pipe of the water collecting pipe, that is, the flow resistance is reduced, so that a large amount of fresh water is obtained.

  The flow path material does not have to reach the edge of the separation membrane. For example, the flow path material is provided at the outer end of the envelope membrane in the winding direction and the end of the envelope membrane in the longitudinal direction of the water collecting pipe. It does not have to be done.

  As shown in FIG. 7, the separation membrane forms a separation membrane leaf (hereinafter, membrane leaf). A membrane leaf is a set of two separation membranes cut to a length that facilitates winding. In the membrane leaf 81, the supply-side surface 21 of the separation membrane 1 is disposed so as to face the supply-side surface 71 of the other separation membrane 7 with the supply-side flow path member 4 interposed therebetween. At this time, a supply-side flow path is formed between the supply-side surfaces of the separation membranes facing each other, and a permeation-side flow path is formed between the permeation-side surfaces.

On the supply side surface of the separation membrane, the inner end in the winding direction is closed by folding or sealing. In the case of folding, the sealing work can be omitted, and in the case of sealing, the handleability is enhanced when manufacturing the separation membrane element. Since the supply side surface of the separation membrane is sealed rather than folded, bending at the end of the separation membrane hardly occurs. Even if it is folded, it is rare that bending occurs, but it is preferable to apply heat to the crease and press it, so that the crease is easily formed.
In the present invention, the membrane leaf is composed of a membrane leaf (A) in which a resin is fixed to at least the permeation side surface of the separation membrane and a membrane leaf (B) to which such a resin is not fixed.

  Further, the membrane leaf (A) and the membrane leaf (B) are alternately laminated, so that an envelope-like membrane having a preferable structure can be formed as will be described later. It becomes a separation membrane element excellent in removability.

  However, for convenience of explanation, in the separation membrane element and the explanation related thereto, the “separation membrane” includes a separation membrane that does not include the permeate-side flow path material (for example, a membrane that has the same configuration as the separation membrane main body).

  Further, as shown in FIG. 8, the membrane leaf (A) and the membrane leaf (B) are alternately stacked, so that the separation membrane 1 and another membrane leaf facing the permeation side surface 22 of the separation membrane 1 are obtained. The separation membrane 7 and the permeation side flow path member 3 existing between the separation membrane 1 and the separation membrane 7 form an envelope-shaped membrane 82. In the envelope-shaped membrane, between the opposing permeate side surfaces, the permeate flows through the permeate-side flow path material 3 and the water collecting pipe, so that only one side inside the winding direction is opened in the rectangular shape of the separation membrane. The three sides are sealed. The permeate is isolated from the supply water by this envelope membrane.

  As described above, since an envelope-shaped film is formed by one set of membrane leaf (A) and one set of membrane leaf (B), the number of each membrane leaf needs to be made uniform. Therefore, in the present invention, a total number of membrane leaves are required.

  Examples of the sealing include a form bonded by an adhesive or hot melt, a form fused by heating or laser, and a form in which a rubber sheet is sandwiched. Sealing by adhesion is particularly preferable because it is the simplest and most effective.

When two or more types of membrane leaves have almost the same membrane performance, all membrane leaves are used for filtration evenly during operation, resulting in performance differences between membrane leaves even during long-time operation. As a result, the life of the separation membrane element is improved. Specifically, “each membrane performance is substantially equal” means that the coefficient of variation of the amount of water produced is 15% or less and the coefficient of variation of the removal rate is 15% or less. The variation coefficient of the amount of fresh water is more preferably 10% or less, and the variation coefficient of the removal rate is further preferably 10% or less.
(2-3) Permeation side flow path As described above, the separation membrane 1 includes the permeation side flow path material 3. By the permeation side flow path material 3, a permeation side flow path is formed inside the leaf, that is, between the permeation side surfaces of the facing separation membranes.
(2-4) Supply-side flow path The separation membrane element 100 includes a flow-path material 4 that has a projected area ratio with respect to the separation membrane 1 exceeding 0 and less than 1 between the surfaces on the supply side of the overlapping separation membranes. The projected area ratio of the supply-side channel material is preferably 0.03 or more and 0.50 or less, more preferably 0.10 or more and 0.40 or less, and particularly preferably 0.15 or more and 0.35 or less. . When the projected area ratio is 0.03 or more and 0.50 or less, the flow resistance can be suppressed to be relatively small. The projected area ratio refers to the projected area obtained when the separation membrane and the supply-side channel material are cut out at 5 cm × 5 cm, and the supply-side channel material is projected onto a plane parallel to the surface direction of the separation membrane. Divided value.

  As will be described later, the height of the supply-side channel material is preferably more than 0.5 mm and not more than 2.0 mm, more preferably not less than 0.6 mm and not more than 1.0 mm, considering the balance of performance and the operation cost.

The shape of the supply-side channel material is not particularly limited, and may have a continuous shape or a discontinuous shape. Examples of the channel material having a continuous shape include members such as a film and a net. Here, the continuous shape means that it is continuous over the entire range of the flow path material. The continuous shape may include a portion where a part of the flow path material is discontinuous to such an extent that a problem such as a decrease in the amount of water produced does not occur. The definition of “discontinuity” is as described for the passage-side channel material. The material of the supply side channel material is not particularly limited, and may be the same material as the separation membrane or a different material.
(2-5) Water Collection Pipe The water collection pipe 6 is not particularly limited as long as it is configured so that permeated water flows therethrough. As the water collecting pipe 6, for example, a cylindrical member having a side surface provided with a plurality of holes is used.
(2-6) End Plate As shown in FIG. 6, the separation membrane element 100 includes end plates 91 and 92 attached to both ends of the wound body of the separation membrane 1 in the longitudinal direction of the water collecting pipe 6.

In FIG. 6, the shape of the first end plate 91 and the shape of the second end plate 92 are the same, but in one element, the shapes of the two end plates may be different from each other. In FIG. 6, the first end plate 91 is disposed on the upstream side, and the second end plate 92 is disposed on the downstream side.
[3. Method for manufacturing separation membrane element]
(3-1) Manufacture of separation membrane body The manufacturing method of the separation membrane body has been described above, but it is summarized as follows.

The resin is dissolved in a good solvent, and the resulting resin solution is cast on a substrate and immersed in pure water to combine the porous support layer and the substrate. Thereafter, as described above, a separation functional layer is formed on the porous support layer. Furthermore, in order to improve separation performance and permeation performance as necessary, chemical treatment such as chlorine, acid, alkali, and nitrous acid is performed to wash monomers and the like. In order to improve the handling property of the separation membrane, a drying treatment may be performed after the separation membrane contains a hydrophilic molecule. The continuous sheet | seat of a separation membrane main body is produced as mentioned above.
(3-2) Arrangement of Permeation Side Channel Material When the permeation side channel material is fixed to the separation membrane, the separation membrane manufacturing method provides a discontinuous channel material on the permeation side surface of the separation membrane body. A process is provided. This step may be performed at any time during the manufacture of the separation membrane. For example, the flow path material may be provided before the porous support layer is formed on the base material, or after the porous support layer is provided and before the separation functional layer is formed. It may be performed after the separation functional layer is formed and before or after the above-described chemical treatment is performed.

  The method of arranging the flow path material includes, for example, a step of arranging a soft material on the separation membrane and a step of curing it. Specifically, ultraviolet curable resin, chemical polymerization, hot melt, drying or the like is used for the arrangement of the flow path material. In particular, hot melt is preferably used. Specifically, a step of softening a material such as resin by heat (that is, heat melting), a step of placing the softened material on the separation membrane, and curing the material by cooling. A step of fixing on the separation membrane.

Examples of the method for arranging the flow path material include coating, printing, spraying, and the like. Examples of the equipment used include a nozzle type hot melt applicator, a spray type hot melt applicator, a flat nozzle type hot melt applicator, a roll type coater, an extrusion type coater, a printing machine, and a sprayer.
(3-3) Formation of membrane leaf and envelope membrane As described above, the membrane leaf may be formed by folding the separation membrane so that the surface on the supply side of the separation membrane faces inward, or separately. The two separation membranes may be formed by bonding the supply-side surfaces facing each other. In the latter case, it is preferable to include a step of sealing the inner end of the separation membrane in the winding direction on the surface on the supply side. In the sealing step, the two separation membranes are overlapped so that the surfaces on the supply side face each other. Further, the inner end in the winding direction of the separated separation membrane, that is, the left end in FIG. 7 is sealed. At this time, it is preferable that the two separation membranes have the same type. By using the same type of separation membrane, the difference in performance within the membrane leaf can be suppressed, and stable performance can be maintained throughout the membrane leaf even if the operation is performed for a long time. Examples of the sealing method include adhesion by an adhesive or hot melt, fusion by heating or laser, and a method of sandwiching a rubber sheet. Sealing by adhesion is particularly preferable because it is the simplest and most effective. At this time, a supply-side channel material formed separately from the separation membrane may be disposed between the separated separation membranes.

  Either the supply-side sealing or the permeation-side sealing (envelope-like membrane formation) may be performed first, or the supply-side sealing is performed while stacking separation membranes. And the sealing of the surface on the transmission side may be performed in parallel. However, in order to suppress the generation of wrinkles in the separation membrane during winding, the adhesive or hot melt at the end in the width direction is allowed to allow the adjacent separation membranes to shift in the length direction due to winding. It is preferable to complete the solidification or the like, that is, the solidification for forming the leaf, after the winding is completed.

At this time, as described above, by alternately laminating the membrane leaf (A) and the membrane leaf (B), only the envelope membrane in which the channel material exists between the permeation side surfaces of the opposing separation membranes Is formed. When only the membrane leaf (A) is laminated, the separation membrane in the envelope-like membrane may be displaced during a long operation, and the flow path material may get stuck in the flow path, resulting in a significant decrease in the amount of water produced. When only the membrane leaf (B) is laminated, the flow path material does not exist in the envelope-like membrane, so that the permeate does not flow efficiently to the water collecting pipe, and a sufficient amount of fresh water may not be obtained.
(3-4) Separation membrane winding For manufacturing the separation membrane element, a conventional element manufacturing apparatus can be used. In addition, as an element manufacturing method, methods described in reference documents (Japanese Patent Publication No. 44-14216, Japanese Patent Publication No. 4-11928, Japanese Patent Application Laid-Open No. 11-226366) can be used. Details are as follows.

  When the separation membrane is wound around the water collecting pipe, the separation membrane is arranged so that the closed end of the leaf, that is, the closed portion of the envelope-shaped membrane faces the water collecting pipe. By winding the separation membrane around the water collecting pipe in such an arrangement, the separation membrane is wound in a spiral shape.

If a spacer such as a tricot or base material is wound around the water collection pipe, the adhesive applied to the water collection pipe will not flow easily when the element is wound, leading to suppression of leakage, and the flow path around the water collection pipe is stable. Secured. The spacer may be wound longer than the circumference of the water collecting pipe.
(3-5) Other steps The method of manufacturing a separation membrane element may include further winding a film, a filament, and the like around the outer periphery of the wound membrane of the separation membrane formed as described above. Further steps such as edge cutting for aligning the end of the separation membrane in the longitudinal direction of the water collecting pipe, attachment of an end plate, and the like may be included.
[4. (Use of separation membrane element)
The separation membrane element manufactured as described above may be further used as a separation membrane module by being connected in series or in parallel and housed in a pressure vessel.

  Further, the separation membrane element and the module described above can be combined with a pump for supplying fluid to them, a device for pretreating the fluid, and the like to constitute a fluid separation device. By using this separation device, for example, the supplied water can be separated into permeated water such as drinking water and concentrated water that has not permeated through the membrane, and water suitable for the purpose can be obtained.

  The higher the operating pressure of the fluid separation device, the better the desalination rate, but the energy required for operation also increases, and considering the retention of the supply channel and permeation channel of the separation membrane element, the membrane module The operating pressure at the time of passing the water to be treated is preferably 0.2 MPa or more and 5 MPa or less. As the feed water temperature increases, the salt desalting rate decreases, but as the feed water temperature decreases, the membrane permeation flux also decreases. In addition, when the pH of the feed water becomes high, scales such as magnesium may be generated in the case of feed water with a high salt concentration such as seawater, and there is a concern about deterioration of the membrane due to high pH operation. Is preferred.

  The fluid to be treated by the separation membrane element is not particularly limited, but when used for water treatment, as feed water, seawater, brine, wastewater, etc., 500 mg / L to 100 g / L TDS (Total Dissolved Solids: total dissolved solids) For example). In general, TDS refers to the total dissolved solid content, and is expressed as “mass ÷ volume” or “weight ratio”. According to the definition, the solution filtered through a 0.45 micron filter can be calculated from the weight of the residue by evaporating at a temperature of 39.5 to 40.5 ° C., but more simply converted from practical salt (S) To do.

  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.

(Permeation flux of separation membrane)
Operation was carried out for 1 hour under conditions of an operating pressure of 0.5 MPa and an operating temperature of 25 ° C. using a saline solution having a concentration of 200 mg / L and pH 6.5 as the feed water. The amount of permeated water obtained was expressed as the membrane permeation flux (m ³ / m ² / day) with the amount of water per day (cubic meter) per square meter of membrane surface.

(Desalination rate of separation membrane (TDS removal rate))
For the permeated water sampled during the measurement of the permeation flux, the electrical conductivity was measured and the TDS concentration was calculated. The TDS removal rate was calculated by applying the TDS concentration of the permeated water and the TDS concentration of the feed water to the following equation.
TDS removal rate (%) = 100 × {1− (TDS concentration in permeated water / TDS concentration in raw water)}.

(Permeation flux of separation membrane leaf, coefficient of variation of desalination rate)
About each membrane leaf used for preparation of the separation membrane element, 20 places were sampled at random, and the permeation flux and the desalination rate were evaluated by the method described above. The average value at 20 locations was defined as the permeation flux of the membrane leaf and the desalination rate.

  From the permeation flux or desalination rate of all membrane leaves used, the average value and standard deviation thereof were calculated, and the value obtained as standard deviation / average value × 100 was obtained as the permeation flux or desalination rate between membrane leaves. Coefficient of variation.

(Water generation capacity of separation membrane element)
The amount of water per day obtained by one separation membrane element when operating under the conditions described in the examples was expressed as the amount of water produced (m ³ / day).

(Desalination rate of separation membrane element (TDS removal rate))
For the permeated water obtained by the same operation as in the measurement of the amount of water produced, the same operation as the desalting rate of the separation membrane was performed, and the TDS removal rate was calculated.

(Observation of cross-sectional shape of channel material)
Using a scanning electron microscope (S-800) (manufactured by Hitachi, Ltd.), a cross section of any 30 transmission side flow path members was photographed at 500 times, and the shape was observed.
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).

  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 blowing, and washed with hot water at 80 ° C. for 1 minute.

  The obtained separation membrane was folded and cut so that the surface on the supply side was opposed, and a net (thickness: 0.70 mm, pitch: 3 mm × 3 mm, fiber diameter: 0.34 mm, projected area ratio: 0.13) As a supply-side channel material, one leaf 1 having a width of 300 mm and a leaf length of 750 mm was produced.

  Subsequently, the permeation | transmission side flow-path material was formed over the permeation | transmission side of the obtained separation membrane. That is, using a gravure roll while adjusting the temperature of the backup roll to 15 ° C., a saponified ethylene-vinylacetic acid copolymer (Mersen H-6820 manufactured by Tosoh Corporation, compression modulus: 1 GPa) is passed through the separation membrane. It applied to the surface continuously in the length direction. The resin temperature was 135 ° C., and the processing speed was 10 m / min. The cross-sectional shape of the channel material thus formed was a trapezoid with an upper base of 0.45 mm and a lower base of 0.55 mm. In addition, the height c of the flow path material is 0.26 mm, the width d of the flow path material is 0.5 mm, the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the water collecting pipe is 90 °, and the width The channel material interval e in the direction was 0.4 mm, and the channel material pitch in the width direction was 0.9 mm. The separation membrane thus obtained was folded so that the surfaces on the supply side face each other, and the above-mentioned net was sandwiched as a supply-side channel material to produce one membrane leaf 2 having a width of 300 mm and a leaf length of 750 mm.

  Here, the pitch is an average value of the horizontal distances from the vertexes of the convex portions of the separation membrane to the vertexes of the neighboring convex portions, measured at 200 locations on the transmission side surface.

  After laminating the two types of membrane leaves thus obtained and winding them in a spiral shape around a water collecting pipe made of ABS (width: 300 mm, diameter: 17 mm, 12 holes × one straight line), and further winding a film around the outer periphery After fixing with tape, edge cutting and end plate attachment were performed to produce a separation membrane element of 2 inch size (hereinafter referred to as “2 inch element”).

  The separation membrane element was placed in a pressure vessel and operated for 1 hour and 60 days under conditions of 500 ppm salt as raw water, an operating pressure of 0.5 MPa, an operating temperature of 25 ° C., and a pH of 6.5 (recovery rate of 15%). . The element performance and parameters at this time are as shown in Table 1.

(Example 2)
The same method as in Example 1 except that the separation membrane was prepared by the same method as in Example 1 and then the nitrite treatment was performed by immersing in a 3000 ppm sodium nitrite aqueous solution for 45 seconds at pH 3, 35 ° C. A 2-inch element was produced and evaluated for performance. The element performance and parameters at this time are as shown in Table 1.

(Example 3)
The same method as in Example 1, except that the separation membrane was prepared in the same manner as in Example 1, then the separation membrane was immersed in a 10% glycerol aqueous solution at 25 ° C., and further dried at 80 ° C. for 2 minutes. A 2-inch element was produced and evaluated for performance. The element performance and parameters at this time are as shown in Table 1.

Example 4
The same method as in Example 2, except that the separation membrane was prepared in the same manner as in Example 2, then the separation membrane was immersed in a 10% glycerin aqueous solution at 25 ° C., and further dried at 60 ° C. for 2 minutes. A 2-inch element was produced and evaluated for performance. The element performance and parameters at this time are as shown in Table 1.

(Example 5)
Except that the drying temperature of the separation membrane was set to 160 ° C. in Example 3, a 2-inch element was produced in the same manner as in Example 3, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Example 6)
Except that the drying temperature of the separation membrane was set to 160 ° C. in Example 4, a 2-inch element was produced in the same manner as in Example 4 and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.
(Example 7)
About two types of leaves used in Example 1, after producing two separation membranes having a width of 300 mm and a length of 375 mm, they are arranged so that the supply water sides face each other, and a sealing material (manufactured by Tosoh Corporation) A 2-inch element was produced in the same manner as in Example 1 except that it was produced by using an ethylene vinyl acetate copolymer product name Ultrasen 627), and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Example 8)
In Example 4, all operations were performed except that the processing speed was 7 m / min, the cross-sectional shape of the channel material was a width of 0.54 mm, a height of 0.26 mm, and a semi-elliptical shape as shown in FIG. A 2-inch element was produced by the same method as in Example 4, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

Example 9
In Example 4, a 2-inch element was produced by the same method as in Example 4 except that the drying treatment temperature of the separation membrane was 160 ° C., and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Example 10)
In Example 9, everything was carried out except that the processing speed was 7 m / min, the cross-sectional shape of the channel material was 0.54 mm in width, 0.26 mm in height, and a semi-elliptical shape as shown in FIG. A 2-inch element was produced by the same method as in Example 9, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Example 11)
In Example 4, the temperature of the backup roll was adjusted to 10 ° C., except that the upper base was 0.45 mm, the lower base was 0.55 mm, the corner was R = 0.02 mm, and a rounded trapezoid as shown in FIG. All of the 2-inch elements were produced by the same method as in Example 4 and the performance was evaluated. The element performance and parameters at this time are as shown in Table 1.

(Comparative Example 1)
Except that the permeate-side channel material was formed on any of the two membrane leaves used in Example 1, a 2-inch element was produced in the same manner as in Example 1, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Comparative Example 2)
Of the two membrane leaves used in Comparative Example 1, only a membrane leaf 2 was subjected to the same nitrous acid treatment as in Example 2, and a 2-inch element was produced in the same manner as in Comparative Example 1, Evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Comparative Example 3)
A separation membrane was prepared by the same method as in Example 3, and after drying, it was folded and cut so that the surfaces on the supply side face each other, and the same net as in Example 1 was sandwiched as a supply-side channel material. Then, a tricot (thickness: 260 μm, groove width: 200 μm, ridge width: 300 μm, groove depth: 105 μm) is laminated on the permeate-side surface of the separation membrane as a permeate-side channel material, and has a width of 300 mm and a leaf length of 750 mm. Two leaves were produced. With respect to the leaf thus obtained, a 2-inch element was produced by the same method as in Example 1, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

(Comparative Example 4)
A 2-inch element was produced in the same manner as in Example 8 except that a permeate-side channel material was produced on any of the two membrane leaves used in Example 8, and performance evaluation was performed. The element performance and parameters at this time are as shown in Table 1.

  From the results shown in Table 1, it is clear that Examples 1-4 and 7, 8, and 11 maintain a high amount of fresh water and a high removal rate even during long-time operation. In particular, as in Examples 8 and 11, by using a rounded resin shape, a separation membrane element having excellent performance stability in a long-time operation could be produced.

  In Example 5, since the drying treatment temperature was set high, the permeation flux of the separation membrane leaf 2 was remarkably lowered, so the variation coefficient of the permeation flux between the separation membranes exceeded 10%. However, since the coefficient of variation of the desalination rate is less than 10%, as a result, a high amount of fresh water and a high removal rate were maintained even during long-time operation.

  Similarly, in Example 6, since the removal rate of the separation membrane leaf 2 was remarkably improved by setting the drying treatment temperature high, the variation coefficient of the desalting rate between the separation membranes exceeded 10%. However, since the coefficient of variation of the permeation flux is less than 10%, as a result, a high amount of fresh water and a high removal rate were maintained even during long-time operation.

  In Example 9, since the drying treatment temperature was set high, the permeation flux of the separation membrane leaf 2 greatly decreased, and the coefficient of variation of the permeation flux between the separation membranes and the desalination rate exceeded 15%. Although the decrease in the amount of water produced was somewhat large in operation over time, a separation membrane element capable of sufficiently obtaining the effects of the present invention could be produced.

  Similarly, in Example 10, the drying treatment temperature was set high. However, since the cross-sectional shape of the resin is a semi-elliptical shape, the decrease in the amount of water produced in long-time operation is suppressed more than in Example 9, and the high The amount of water and high removal rate were maintained.

  On the other hand, in Comparative Examples 1 and 4, since the resin is fixed on the permeate side of both membrane leaves 1 and 2, the membrane is displaced during a long period of operation, and the channel material gets stuck in the channel. Decreased significantly.

  In Comparative Example 2, the post-treatment was performed only on the membrane leaf 2 so that the permeation flux between the separation membranes and the coefficient of variation of the desalination rate both exceeded 10%. As a result, the performance change between the membrane leaves became large in the long-time operation, and the performance as an element was finally significantly lowered.

  In Comparative Example 3, tricot was used as the permeate-side channel material, so that the membrane fell during long-time operation, and the permeate-side channel was reduced, resulting in an increase in flow resistance and a marked reduction in the amount of water produced.

  As described above, it was found that the separation membrane elements of Examples 1 to 10 maintained a high amount of fresh water and a high removal rate even during long-time operation.

  The composite separation membrane element of the present invention can be particularly suitably used for desalination of brine and seawater.

DESCRIPTION OF SYMBOLS 1 Separation membrane 2 Separation membrane main body 21 Supply side surface 22 Permeation side surface 201 Base material 202 Porous support layer 203 Separation functional layer 3 Permeation side flow channel material 4 Supply side flow channel material 5 Permeation side flow channel 6 Water collecting pipe 7 Separation membrane body 71 Supply side surface 72 Permeation side surface 81 Separation membrane leaf 82 Envelope membrane 91 First end plate 92 Second end plate 100 Separation membrane element a Separation membrane (leaf) length b Permeation side channel material Width in the c direction c Height of the permeate channel material d Width of the permeate channel material e Interval in the length direction of the permeate channel material f Length of the permeate channel material

Claims (4)

Water collecting pipe,
A separation membrane leaf wound in a state of being laminated around the water collecting pipe, having a separation membrane sandwiching the supply side flow passage material from both sides so that the supply side flow passage material faces inward A separation membrane element comprising:
The separation membrane element includes at least the following separation membrane leaves of (1) and (2), and the separation membrane leaves of (1) and (2) are alternately stacked.
(1) Having a permeate-side flow channel material with resin fixed on the permeate side surface of the separation membrane (2) No resin fixed on the permeate side surface of the separation membrane The variation coefficient of the water production amount of the separation membrane leaf of (1) and (2) is 15% or less, and the variation coefficient of the removal rate is 15% or less.
The separation membrane element according to claim 1. The variation coefficient of the water production amount of the separation membrane leaf of (1) and (2) is 10% or less, and the variation coefficient of the removal rate is 10% or less.
The separation membrane element according to claim 1 or 2. The permeation side channel material has a length in the length direction of the separation membrane larger than a length in a width direction perpendicular to the length direction,
In the width direction, they are spaced apart from each other,
In a cross section perpendicular to the length direction, at least a part of the circumference not fixed to the separation membrane is rounded,
The separation membrane element according to claim 1.

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