Patent Description:
In recent years, usage of fluid separation elements using separation membranes has been increased rapidly in various fluid separation fields using water permeated through the membranes or liquid concentrated by the membranes, such as seawater desalination applications, ultrapure water applications in a semiconductor field, general brackish water applications, organic substance separating applications, waste water reusing application, etc..

Examples of forms of fluid separation elements include a type using a hollow fiber membrane, a plate frame type of a flat membrane, and a spiral type. Among them, the spiral type fluid separation element has a structure in which a separation membrane is spirally wound around a water collection tube together with a permeate channel material and a raw water channel material. Raw water is supplied from one end surface of the fluid separation element, and treated by the separation membrane. The permeate which has been permeated through the separation membrane is taken out from the water collection tube, while the raw water which has not been permeated through the separation membrane is discharged as concentrated liquid from the other end surface of the fluid separation element.

In a typical form of the spiral type fluid separation element, an outer circumferential portion thereof is reinforced with an outer shell including fiber reinforced plastic (Fiber Reinforced Plastic (FRP)) of glass fiber and epoxy resin, and anti-telescoping plates are attached to the axially both ends of the fluid separation element.

A seal member called a brine seal is provided on the anti-telescoping plate on the upstream side of the fluid separation element so as to prevent raw water from passing through a short path into a gap between the outer shell of the fluid separation element and a pressure vessel. The brine seal may be an O-ring or the like, but a U-seal or the like is often used as the brine seal owing to its loadability to the pressure vessel.

When such fluid separation elements are used, about one to six fluid separation elements are loaded and used in series in a pressure vessel, and a number of such pressure vessels are placed on a rack to perform large-volume treatment.

In the background art, a fluid separation element has been known in which a groove is provided in each anti-telescoping plate so that an outer shell of the fluid separation element can be inserted externally in the groove in order to prevent the outer shell from moving in an axial direction of the fluid separation element (for example, see Patent Literature <NUM>). Further, an anti-telescoping member for membrane elements is known from Patent Literature <NUM> having a plurality of types of undulations of different shapes on the circumference of an extension that extends from the main body. The exterior finishing material of the membrane roll body is attached to the circumference of the extension so that the plurality of types of undulations are in contact with the exterior finishing material.

Further, <CIT>, <CIT>, <CIT> and <CIT> disclose spiral wound membrane modules with anti-telescoping devices.

In this structure, it is indeed possible to suppress the outer shell from moving in the axial direction of the fluid separation element relatively to each anti-telescoping plate, but it is not possible to suppress the outer shell from moving in a rotation direction.

When the outer shell rotates relatively to the each anti-telescoping plate during operation, the spirally wound body may rotate together to cause collapse of the spirally wound body structure or damage on a surface of the separation membrane.

An object lying in the background of the present invention is to suppress the outer shell and each anti-telescoping plate from being displaced from each other in the rotation direction when raw water is supplied to the fluid separation element. Specifically, an object of the present invention is to suppress the outer shell from rotating even if force is applied in a direction to rotate the outer shell relatively to the each anti-telescoping plate when the fluid separation element loaded in a pressure vessel is operated.

In order to attain the foregoing object, a fluid separation element and an anti-telescoping plate are configured as defined in the claims. Features of various preferred embodiments follow from the dependent claims as well as the subsequent description and enclosed Figures.

An advantageous effect obtained by the fluid separation element according to the present invention is that it is possible to suppress the outer shell from rotating relatively to each anti-telescoping plate even if force is generated in a direction to rotate the outer shell or the anti-telescoping plate when the fluid separation element is in use.

In addition, there is a method in which the spirally wound body and each anti-telescoping plate are fixed by a tape when the fluid separation element is manufactured, but the third annular portion and the first annular portion are covered with the tape on this occasion. Thus, even when depressions are provided in the third annular portion and the first annular portion, the depressions may exhibit no effect. When the positions of the depressions are limited to a side surface of the second annular portion on the spirally wound body side, the depressions can exhibit an effect even if the spirally wound body and the each anti-telescoping plate are fixed by a tape. Thus, the fluid separation element can be manufactured effectively.

<FIG> is a schematic partial development showing an embodiment of a fluid separation element to which the present invention is applied.

The fluid separation element is a spiral type fluid separation element, in which one unit or a plurality of units are prepared and spirally wound around a water collection tube <NUM>. Each unit includes a first separation membrane <NUM>, a second separation membrane <NUM>, a permeate channel material <NUM> and a raw water channel material <NUM>. In each unit, the first separation membrane <NUM> and the second separation membrane <NUM> are bonded to each other at their three sides to form an envelope-like membrane into which the permeate channel material <NUM> is inserted. The envelope-like membrane including the first separation membrane <NUM> and the second separation membrane <NUM> has a structure in which the first separation membrane <NUM> and the second separation membrane <NUM> are bonded at, of the four sides of the envelope-like membrane, all the sides except for the side on the water collection tube <NUM> side. The envelope-like membrane is open on the water collection tube <NUM> side. Raw water <NUM> is supplied from one end surface of the fluid separation element, and treated in an effective membrane portion <NUM> (see <FIG>) which is a part where the first separation membrane <NUM> and the second separation membrane <NUM> are not bonded with each other. Permeate <NUM> which has been permeated through the separation membranes <NUM> and <NUM> is taken out from the water collection tube <NUM>, and the raw water <NUM> which has not been permeated through the separation membranes <NUM> and <NUM> is discharged as concentrate <NUM> from the other end surface of the fluid separation element.

Typically the spiral type fluid separation element has a form in which an outer circumferential portion thereof is reinforced with an outer shell <NUM>, and anti-telescoping plates <NUM> are attached to the longitudinally both ends. Examples of raw materials of the outer shell include fiber reinforced plastic (FRP) containing urethane resin, epoxy resin or the like, a plastic film containing polyethylene or polypropylene, etc. The outer shell is preferably an FRP shell including fiber reinforced plastic (FRP) from the viewpoint of pressure resistance, and more preferably an FPR shell including fiber reinforced plastic (FRP) containing glass fiber and epoxy resin from the viewpoint of heat resistance.

<FIG> is a sectional enlarged view showing, of the spiral type fluid separation element according to the present invention, vicinities of a contact portion between an outer circumferential annular portion of an anti-telescoping plate <NUM> and the outer shell <NUM>.

In addition, <FIG> is a sectional enlarged view showing, of the spiral type fluid separation element according to the present invention, the vicinities of the contact portion between the outer circumferential annular portion of the anti-telescoping plate <NUM> and the outer shell <NUM> when a brine seal <NUM> is attached.

Each anti-telescoping plate <NUM> according to the present invention includes a first annular portion <NUM> which can retain the outer shell <NUM>, and a second annular portion <NUM> which is formed on the axially outer side of the first annular portion and in which an outer end portion of the outer shell <NUM> can be locked therein. Preferably the anti-telescoping plate <NUM> further includes a third annular portion <NUM> which is formed on the axially inner side of the first annular portion <NUM> and has an annular shape with a larger outer diameter than that of the first annular portion. Owing to the existence of the third annular portion <NUM>, a step is made between the first annular portion <NUM> and the third annular portion <NUM> so that the outer shell <NUM> can be locked more easily, and axial displacement between the outer shell and the anti-telescoping plate can be more suppressed. In addition, a depression <NUM> is provided on a side surface of the second annular portion <NUM> on the axially inner side (specifically a side surface on the spirally wound body side when the anti-telescoping plate <NUM> is attached to the fluid separation element).

Preferably the anti-telescoping plate <NUM> further includes a fourth annular portion <NUM> which is formed on the axially outer side of the second annular portion <NUM> and in which the brine seal <NUM> can be externally inserted thereinto as shown in <FIG>, and a fifth annular portion <NUM> which is formed on the axially outer side of the fourth annular portion <NUM> and in which the brine seal <NUM> can be locked therein. However, even when the fourth annular portion <NUM> and the fifth annular portion <NUM> are absent, the effects of the present invention can be exhibited.

Incidentally, in <CIT>, an anti-telescoping plate in which the fourth annular portion <NUM> and the fifth annular portion <NUM> are absent is exemplified.

In this example, a part of an outer side surface of a second annular portion of the anti-telescoping plate has a concavo-convex portion, and the concavo-convex portion has a complementary shape to a concavo-convex portion on an anti-telescoping plate opposed thereto. The concavo-convex portion bites the opposed concavo-convex portion complementarily so that the anti-telescoping plates opposed to each other can be sealed liquid-tightly, thereby playing a role as the brine seal <NUM>.

The fluid separation element according to the present invention can be manufactured as follows. That is, the separation membranes <NUM> and <NUM> being formed into an envelope-like membrane and having the permeate channel material <NUM> inserted thereinto are wound around the water collection tube <NUM> together with the raw water channel material <NUM> so as to form a spirally wound body <NUM>. The anti-telescoping plates <NUM> according to the present invention are fixed to the end surfaces of the spirally wound body <NUM> by taping or the like. Then, a resin composition for forming an outer shell is wound on the outer circumference of the spirally wound body <NUM> and the anti-telescoping plates <NUM>. After that, the resin composition is hardened to produce the fluid separation element according to the present invention. Since the resin composition is hardened in a state that the resin composition has entered the first annular portion <NUM> and the depression <NUM> of each anti-telescoping plate <NUM>, the outer shell <NUM> formed after the resin composition is hardened is firmly fixed to the anti-telescoping plates <NUM>. Therefore, even if force is applied in a direction to rotate the outer shell relatively to each anti-telescoping plate, the outer shell can be suppressed from rotating.

<FIG> is a view in which, among shapes which the anti-telescoping plate according to the present invention can be formed into, a preferred shape is observed from the spirally wound body side.

Each anti-telescoping plate <NUM> is constituted by an outer ring portion <NUM> constituted by the third annular portion <NUM>, the first annular portion <NUM>, the second annular portion <NUM>, the fourth annular portion <NUM> and the fifth annular portion <NUM> as shown in <FIG>; an inner ring portion <NUM> formed of a ring with a smaller outer diameter than that of the outer ring portion <NUM> as shown in <FIG>; and spokes <NUM> connecting the outer ring portion <NUM> and the inner ring portion <NUM> with each other. Preferably the inner diameter of the inner ring portion <NUM> is larger than the outer diameter of the water collection tube <NUM>.

In the fluid separation element according to the present invention, the depression <NUM> is provided on a side surface <NUM> (side surface of a second annular portion on a spirally wound body side) of the second annular portion <NUM> on the spirally wound body side of each anti-telescoping plate <NUM> in order to prevent the outer shell <NUM> from rotating relatively to the each anti-telescoping plate <NUM>. The outer shell <NUM> and the anti-telescoping plate <NUM> are externally inserted into the first annular portion <NUM>, and brought into contact with the second annular portion <NUM>. On this occasion, a part of the outer shell <NUM> enters the depression <NUM> on the second annular portion <NUM> so as to have a shape in which an anchor is driven from the outer shell <NUM> to the anti-telescoping plate <NUM>. Thus, the outer shell <NUM> is suppressed from rotating relatively to the each anti-telescoping plate <NUM>.

A sectional shape or position of the depression <NUM> appearing when the second annular portion <NUM> is sectionally cut by a plane passing the central axis of a corresponding one of the anti-telescoping plates <NUM> preferably differs in the circumferential direction of the second annular portion <NUM>. Here, the phrase "a sectional shape or position of the depression <NUM> appearing when the second annular portion <NUM> is sectionally cut differs in the circumferential direction of the second annular portion <NUM>" means that the shape or position appearing when the second annular portion <NUM> is sectionally cut by an arbitrary plane passing the central axis of a corresponding one of the anti-telescoping plates <NUM> may differ depending on the planes. In a case where the sectional shape or position of the depression <NUM> is uniform in the circumferential direction of the second annular portion <NUM>, there is no anchor for preventing the outer shell <NUM> and the anti-telescoping plate <NUM> from rotating relatively to each other even if a part of the outer shell <NUM> enters into the depression <NUM>. Therefore, the effects of the present invention may not be sufficiently exhibited.

The brine seal <NUM> is externally inserted to the anti-telescoping plate <NUM> on the upstream side of the fluid separation element so as to prevent raw water from passing through a short path into a gap between the outer shell of the fluid separation element and a pressure vessel. The brine seal may be an O-ring or the like, but a U-seal, a split ring seal or the like is often used as the brine seal owing to its loadability to the pressure vessel. Particularly for the U-seal, a U-part thereof is opened when fluid flows therein from the upstream side, so that the anti-telescoping plate and the pressure vessel can be sealed liquid-tightly.

Each of <FIG>, <FIG>, <FIG>, <FIG> and <FIG> is a view in which, among the shapes which the anti-telescoping plate according to the present invention can be formed into, a preferred shape is observed from the spirally wound body side.

As a preferred shape, for example, a method in which a total of <NUM> depressions <NUM> are provided, with intervals of <NUM> degrees, on the side surface <NUM> of the second annular portion on the spirally wound body side as shown in <FIG>, may be used.

According to an alternative shape, there may be one arc-like depression <NUM> on the side surface <NUM> of the second annular portion on the spirally wound body side as shown in <FIG>.

According to an alternative shape, there may be depressions <NUM> on an outer circumferential part of the side surface <NUM> of the second annular portion on the spirally wound body side as shown in <FIG>.

According to an alternative shape, whole part of the side surface <NUM> of the second annular portion on the spirally wound body side, excluding a part thereof, may form a depression <NUM> as shown in <FIG>.

According to an alternative shape, depressions <NUM> may be formed of parts of arcs of two or more concentric circles having the same sectional shape. In this case, the sectional shape of each depression <NUM> appearing when the second annular portion <NUM> is sectionally cut by a plane including the central axis of the anti-telescoping plate <NUM> is uniform independently of the plane. However, since the sectional positions of the depression <NUM> differs, this is a preferable shape for exhibiting the effects of the present invention.

Only in order to prevent the outer shell <NUM> from rotating, each depression <NUM> made on the side surface <NUM> of the second annular portion on the spirally wound body side may be a through hole penetrating the second annular portion <NUM>. However, when epoxy resin enters onto the fourth annular portion <NUM> through the through hole, there is a concern that the brine seal <NUM> cannot be attached. Therefore, it is preferable that the depression <NUM> is a depression.

The upper limit of the depth of the depression <NUM> is preferably a depth within a range of not being a through hole, and preferably smaller than the thickness of the second annular portion <NUM> of the anti-telescoping plate <NUM>.

Incidentally, the number of depressions for preventing the rotation is preferably one or more.

The total volume of the depressions <NUM> is preferably <NUM>% or more and more preferably <NUM>% or more of the total volume of the second annular portion <NUM> in order to exhibit the effect of suppressing the rotation.

When the total volume of the depressions <NUM> increases, the amount of epoxy resin required for forming the outer shell increases. It is therefore preferable that the total volume of the depressions <NUM> is about less than <NUM>% of the total volume of the second annular portion <NUM>.

<FIG> is a more preferable sectional shape in vicinities of a part where the water collection tube <NUM> and the anti-telescoping plate <NUM> are in contact with each other. As shown in <FIG>, a structure that depressions <NUM> are provided in a part on the water collection tube <NUM> where the anti-telescoping plate <NUM> and the water collection tube <NUM> are in contact with each other is more preferable. Alternatively, the depressions <NUM> may be provided in a part on the anti-telescoping plate <NUM> where the anti-telescoping plate <NUM> and the water collection tube <NUM> are in contact with each other. On this occasion, the water collection tube <NUM> and the anti-telescoping plate <NUM> are bonded to each other through a bonding agent, and the bonding agent entering into the depressions of the water collection tube is hardened so that the anti-telescoping plate <NUM> can be suppressed from rotating relatively to the water collection tube <NUM>.

Next, the fluid separation element using the anti-telescoping plates according to the present invention will be described along its specific examples. However, the present invention is not limited by these examples.

As shown in <FIG>, a total of <NUM> depressions <NUM> were provided, with intervals of <NUM> degrees, on a side surface <NUM> of a second annular portion on a spirally wound body side in each anti-telescoping plate <NUM>. Each depression <NUM> had a diameter of <NUM> and a depth of <NUM>, and the total volume of the depressions <NUM> was <NUM><NUM>, which occupied <NUM>% of the total volume of the second annular portion <NUM>.

A fluid separation element was manufactured using the aforementioned anti-telescoping plates. As shown in <FIG>, the fluid separation element had a structure in which an outer shell <NUM> including FRP was provided on the outer circumference of a spirally wound body <NUM> in which a first separation membrane <NUM>, a second separation membrane <NUM>, a permeate channel material <NUM> and a raw water channel material <NUM> were spirally wound, while the anti-telescoping plates <NUM> were disposed in the both end portions of the spirally wound body <NUM> and the outer shell <NUM>.

In addition, <FIG> is a schematic view showing a form of an envelope-like membrane for use in the spiral type fluid separation element according to the present invention. The envelope-like membrane used in the spirally wound body <NUM> has a combination of the first separation membrane <NUM> and the second separation membrane <NUM> so that the first separation membrane <NUM> is <NUM> shorter than the second separation membrane <NUM>, as shown in <FIG>.

On this occasion, a bonding agent used for bonding the first separation membrane <NUM> and the second separation membrane <NUM> leaks wholly or partially from an outer circumferential bonding portion <NUM> of the envelope-like membrane.

Thus, outer circumferential end portions <NUM> in the envelope-like membranes adjacent to each other are wholly or partially fixed to each other through the bonding agent. In addition, the bonding agent is in contact with only the other part than the effective membrane portion <NUM> of the first separation membrane <NUM> and the second separation membrane <NUM>. The area of the effective membrane portion <NUM> is <NUM><NUM> or more.

A test water flow test was performed using the aforementioned fluid separation element. One fluid separation element was loaded in a pressure vessel, and operated for five days at five hours per day.

As test water, iron (III) chloride and polyacrylamide were added as flocculant into a <NUM>,<NUM> ppm wheat-flour suspension. Operation pressure was <NUM> MPa.

A rotation angle of the outer shell relative to the anti-telescoping plates was measured after the <NUM>-days operation. The rotation angle was <NUM> degree.

A fluid separation element was manufactured using anti-telescoping plates each having no depression on a surface (a side surface of a second annular portion on the spirally wound body side) in contact with an end surface of an outer shell.

As shown in <FIG>, the fluid separation element had a structure in which an outer shell <NUM> including FRP was provided on the outer circumference of a spirally wound body <NUM> in which a first separation membrane <NUM>, a second separation membrane <NUM>, a permeate channel material <NUM> and a raw water channel material <NUM> were spirally wound, while the anti-telescoping plates <NUM> were disposed in the both end portions of the spirally wound body <NUM> and the outer shell <NUM>.

Claim 1:
An anti-telescoping plate (<NUM>), configured to be provided to one of both end portions of a spirally wound body (<NUM>) and an outer shell (<NUM>) of a fluid separation element, the fluid separation element having an axial direction and comprising:
the spirally wound body (<NUM>) comprising a separation membrane (<NUM>, <NUM>) and a raw water channel material (<NUM>) that are spirally wound around a water collection tube (<NUM>);
the outer shell (<NUM>) provided on an outer circumference of the spirally wound body (<NUM>); and
the anti-telescoping plate (<NUM>),
wherein the anti-telescoping plate (<NUM>) includes at least a first annular portion (<NUM>) capable of retaining the outer shell (<NUM>), and a second annular portion (<NUM>) which is formed on an axially outer side of the first annular portion (<NUM>), in which an outer end portion of the outer shell (<NUM>) can be locked therein, and which has an annular shape with a larger outer diameter than an outer diameter of the first annular portion (<NUM>),
wherein the first and the second annular portions (<NUM>, <NUM>) have side surfaces on the axially inner and axially outer sides, the axially inner and axially outer sides being the side surfaces on the spirally wound body side and the side opposite thereto, respectively,
wherein the anti-telescoping plate (<NUM>) has at least one depression (<NUM>) provided on an axially inner side surface (<NUM>) of the second annular portion (<NUM>),
wherein a part of the outer shell (<NUM>) is capable of entering
the at least one depression (<NUM>) to prevent the outer shell (<NUM>) from rotating relatively to each of the anti-telescoping plates, when the fluid separation element is assembled, and
wherein sectional shapes or positions of the depression (<NUM>) appearing when the second annular portion (<NUM>) is sectionally cut by arbitrary planes passing the central axis of the anti-telescoping plate (<NUM>) differ depending on the planes in a circumferential direction of the second annular portion.