JP5925626B2 - Spiral forward osmosis membrane element and forward osmosis membrane module - Google Patents

Description

  The present invention relates to a spiral forward osmosis membrane element and a forward osmosis membrane module incorporating the spiral forward osmosis membrane element.

  Conventionally, techniques using forward osmosis are known for wastewater treatment, seawater desalination, osmotic pressure power generation, and the like. For example, in seawater desalination, a method using a forward osmosis membrane to dilute concentrated seawater concentrated in the seawater desalination process is known (see, for example, Patent Document 1). In addition, diluted water such as seawater or fresh water having a lower concentration than the concentrated seawater generated at the same time when desalinating seawater using reverse osmosis pressure in a seawater desalination device is passed through a semipermeable membrane. A technique (see, for example, Patent Document 2) that permeates, increases the flow rate on the concentrated seawater side with the positive osmotic pressure energy, and generates power at the increased flow rate is also known. And the spiral type forward osmosis membrane element used for the technique using such a forward osmosis phenomenon is known (for example, refer to patent documents 3).

  By the way, in a spiral type forward osmosis membrane element, liquid movement occurs from a low concentration (low osmotic pressure) liquid to a high concentration (high osmotic pressure) liquid through the membrane. In order to suppress the formation of the concentration polarization layer in the vicinity of the membrane, it is necessary to flow a high concentration (high osmotic pressure) liquid and a low concentration (low osmotic pressure) liquid on both sides of the membrane.

  For example, in the spiral-type forward osmosis membrane element of Patent Document 3, the center of the membrane passes through a bent channel in a membrane leaf that is formed in an envelope shape from the central tube so that a liquid flow occurs on one surface of the membrane. The flow of returning to the tube is generated. In addition, bent flow paths in the plurality of membrane leaves are provided in parallel along the axial direction of the central tube.

JP 2005-279540 A JP 2003-176775 A U.S. Pat. No. 4,033,878

  However, in the spiral type forward osmosis membrane element, as described in Patent Document 3, if the liquid supplied to the central tube is caused to flow through all of the plurality of bent flow paths in order, the liquid is supplied to the central tube. The pressure loss of the resulting liquid stream is very large.

  In view of such circumstances, the present invention provides a spiral type forward osmosis membrane element and a forward osmosis membrane module incorporating the spiral type forward osmosis membrane element, in which the pressure loss of the flow of liquid supplied to the central tube is reduced. The purpose is to provide.

  In order to solve the above-mentioned problems, the present invention provides a membrane leaf in which a plurality of internal flow paths bent from a first opening toward a second opening are provided in parallel, and the membrane leaf is wound and flows at one end. An inlet, an outlet at the other end, a central tube in which a supply hole communicating with the first opening and a recovery hole communicating with the second opening are formed, and each of the plurality of internal flow paths, A plurality of partition walls provided in the central tube so as to be positioned between the supply hole and the recovery hole, and among the plurality of partition walls, the terminal partition wall located closest to the outlet is the A spiral forward osmosis membrane element is provided in which the inside of a central tube is blocked and a through hole is formed in at least one partition wall other than the terminal partition wall.

  Moreover, this invention provides the forward osmosis membrane module provided with the cylindrical pressure vessel and said spiral type forward osmosis membrane element loaded in the said pressure vessel.

  According to the above configuration, since the through hole is formed in at least one partition wall other than the terminal partition wall, the internal channel with respect to the partition wall in which the through hole is formed, and the internal channel adjacent to the internal channel on the outlet side All of the supply holes communicating with the first opening of the flow path communicate with the inside of the central tube on the inlet side from the partition wall in which the through hole is formed. Therefore, since the liquid inside the central tube on the inlet side of the partition wall in which the through hole is formed can flow in parallel through these internal flow paths, the pressure loss of the flow of the liquid supplied to the central tube is reduced. Is done.

Sectional drawing of the forward osmosis membrane module which incorporates the spiral type forward osmosis membrane element which concerns on the 1st Embodiment of this invention 2A is a perspective view of the laminate before being wound around the central tube, and FIG. 2B is a schematic cross-sectional view of the spiral osmotic membrane element in which the laminate is wound around the central tube. The figure which shows typically the flow of the liquid in the internal channel of 1st Embodiment and the membrane leaf. The figure which shows typically the flow of the liquid in the internal flow path of the center pipe | tube and membrane leaf of 2nd Embodiment. The figure which shows typically the flow of the liquid in the internal channel of the center pipe | tube of the spiral type forward osmosis membrane element which concerns on a reference example, and a membrane envelope

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description relates to an example of the present invention, and the present invention is not limited to these.

(First embodiment)
FIG. 1 shows a forward osmosis membrane module 1 incorporating a spiral forward osmosis membrane element 2 according to a first embodiment of the present invention. This forward osmosis membrane module 1 includes a cylindrical pressure vessel 9A called a vessel and a spiral type forward osmosis membrane element 2 loaded in the pressure vessel 9A. Disc-shaped caps 9B are attached to both ends of the pressure vessel 9A.

  On the other hand (left side in FIG. 1), the center supply pipe 7A is attached to the center of the cap 9B. Further, the peripheral supply pipe 8A is attached at a position shifted from the center of the one cap 9B. A central discharge pipe 7B is attached to the center of the other cap 9B (right side in FIG. 1). The peripheral discharge pipe 8B is attached at a position shifted from the center of the other cap 9B.

  One end of the spiral forward osmosis membrane element 2 loaded in the pressure vessel 9A is connected to the center supply pipe 7A by a connector 6A. The other end of the spiral forward osmosis membrane element 2 is connected to the central discharge pipe 7B by a connector 6B.

  The forward osmosis module 1 of the present embodiment is supplied with a first liquid to be concentrated and a second liquid to be diluted with a higher solute concentration than the first liquid. In the present embodiment, the first liquid flows from the center supply pipe 7A toward the center discharge pipe 7B through the inside of the spiral forward osmosis membrane element 2 so as to penetrate the pressure vessel 9A. The first liquid is concentrated by passing through the inside of the spiral forward osmosis membrane element 2. On the other hand, the second liquid is supplied into the pressure vessel 9A from the peripheral supply pipe 8A. The second liquid supplied to the inside of the pressure vessel 9A flows toward the peripheral discharge pipe 8B through the spiral forward osmosis membrane element 2, and is discharged from the peripheral discharge pipe 8B. The second liquid is diluted by passing through the spiral forward osmosis membrane element 2.

  The flow of the first liquid and the flow of the second liquid flow in parallel on both surfaces of a forward osmosis membrane 21 described later of the spiral forward osmosis membrane element 2. Since the solute concentration of the second liquid is higher than the solute concentration of the first liquid, liquid movement occurs through the forward osmosis membrane 21 by the osmosis phenomenon from the first liquid toward the second liquid. Along with this, the flow rate flowing out from the peripheral discharge pipe 8B increases more than the flow rate supplied to the peripheral supply pipe 8A.

  The reason why the first liquid and the second liquid are allowed to flow in parallel on both sides of the forward osmosis membrane 21 is that the concentration polarization layer grows in the vicinity of the forward osmosis membrane 21 and the liquid movement due to the penetration phenomenon from the first liquid to the second liquid occurs. This is to prevent a significant decrease.

  For example, fresh water is used as the first liquid and seawater is used as the second liquid, but the first liquid and the second liquid are not limited to this. Normal seawater may be used as the first liquid, and concentrated seawater having a concentration higher than the normal concentration may be used as the second liquid. That is, the solute concentration may be different between the first liquid and the second liquid. In addition, the 1st liquid which should be concentrated is not only what the density | concentration of 1st liquid is actually concentrated, For example, what does not contain a solute component substantially in 1st liquid like fresh water, for example Including.

  In the present embodiment, the second liquid is supplied after being pressurized by a predetermined pressure. Thus, the method of pressurizing the liquid to be diluted is called PRO (Pressure Retarded Osmosis). A method of supplying both the first liquid and the second liquid to be diluted without pressurization may be used, and the present invention encompasses these methods and is referred to as “forward osmosis” and is used in these applications. The membrane is called “forward osmosis membrane”.

  Next, the configuration of the spiral forward osmosis membrane element 2 will be described in detail with reference to FIGS. 1 and 2.

  Each spiral forward osmosis membrane element 2 has a center tube 3, a laminate 20 wound around the center tube 3, and an exterior material 40 surrounding the laminate 20. Moreover, the end member 5 is arrange | positioned so that the laminated body 20 may be pinched | interposed, and it may be attached to the both ends of the center pipe | tube 3. As shown in FIG. The packaging material 40 is held by the end members 5 on both sides. The end member 5 serves to prevent the laminate 20 wound around the central tube 3 from extending in a telescopic manner.

  The end member 5 includes a cylindrical inner peripheral portion 51 that fits into the central tube 3, and a cylindrical outer peripheral portion 52 that is disposed concentrically with the inner peripheral portion 51 and surrounds the inner peripheral portion 51 while being spaced apart. . The inner peripheral part 51 and the outer peripheral part 52 are connected by a connecting part (not shown). A communication passage 55 through which liquid can flow is formed between the outer peripheral surface of the inner peripheral portion 51 and the inner peripheral surface of the outer peripheral portion 52.

  As shown in FIG. 2A, the central tube 3 includes an inflow port 33 at one end and an outflow port 34 at the other end. A plurality of communication holes 37 are provided side by side in the axial direction of the central tube 3. In the present embodiment, as shown in FIG. 2B, the two rows of the plurality of communication holes 37 aligned in the axial direction of the central tube 3 are positioned farthest from each other in the circumferential direction of the tube wall of the central tube 3. It is provided to become.

  The laminated body 20 has a configuration in which envelope-shaped membrane leaves 23 in which forward osmosis membranes 21 are superimposed on both surfaces of the inner flow path member 22 and outer flow path members 24 are alternately stacked. The inner flow path member 22 is a net made of, for example, resin, and forms a flow path for flowing the first liquid to be concentrated between the forward osmosis membranes 21. The outer flow path member 24 is a net made of, for example, a resin, and forms a high concentration side flow path 20B for flowing the second liquid to be diluted between the membrane leaves 23.

  For example, two continuous osmosis membranes 21 are formed by folding one continuous sheet 25 in half with the outer flow path member 24 interposed therebetween. The membrane leaf 23 is obtained by joining the forward osmosis membranes 21 formed in such a manner on three sides with the inner flow path member 22 interposed therebetween. An adhesive is used for this joining. Further, for example, an extension portion obtained by extending one of the inner flow path members 22 is directly wound around the central tube 3, and both end portions thereof are sealed with an adhesive so as to face the outer peripheral surface of the central tube 21. A cylindrical flow path 20C is formed.

  The configuration of the stacked body 20 is not limited to the configuration shown in FIGS. For example, all the forward osmosis membranes 21 may be connected by folding a continuous sheet into a bellows shape.

  As the forward osmosis membrane 21, for example, a composite membrane in which a skin layer is formed on a porous support can be used.

  An epoxy resin porous film can be used as the porous support. As the skin layer formed on the porous support, a skin layer containing a polyamide-based resin obtained by polymerizing a polyfunctional amine component and a polyfunctional acid halogen component can be used.

  The method for forming the skin layer containing the polyamide resin on the surface of the porous epoxy resin membrane is not particularly limited, and a known method can be used. For example, an interfacial condensation method, a phase separation method, or a thin film coating method can be used. As an example, a skin layer is formed by bringing an aqueous amine solution having a polyfunctional amine component into contact with an organic solution containing a polyfunctional acid halide component, and the skin layer is placed on the porous epoxy resin membrane. You can do that. Examples of the polyfunctional amine component include aromatic, aliphatic, or alicyclic polyfunctional amines. Moreover, these polyfunctional amine components may be used alone or as a mixture. An aromatic, aliphatic, or alicyclic polyfunctional acid halide can be used as the polyfunctional halide component. These polyfunctional acid halide components may be used alone or as a mixture.

  With reference to FIG. 3, the inside of the central tube 3 and the inside of the membrane leaf 23 will be described in detail. FIG. 3 is a cross-sectional view schematically showing the flow of the liquid inside the central tube 3 and inside the membrane leaf 23. For simplicity, only one membrane leaf 23 is shown. As shown in the figure, the liquid flows through the center tube 3 and the membrane leaf 23 from the inlet 33 toward the outlet 34.

  In the membrane leaf 23, the space is partitioned by the joint portion 29 made of the above-described adhesive that joins three sides of the two forward osmosis membranes 21. This space is delimited by a joint 28 made of, for example, an adhesive, which joins the two forward osmosis membranes 21 at approximately the center of the membrane leaf 23 from the side where the joint 29 is not formed to the side facing the side. . Thereby, two internal flow paths 26 aligned in the axial direction of the central tube 3 are formed with the joint portion 28 interposed therebetween. Each internal channel 26 is divided into an upstream side (left side in FIG. 3) and a downstream side (right side in FIG. 3) by a joint portion 27 made of, for example, an adhesive that joins the two forward osmosis membranes 21 to each other. . By the joint portions 27 to 29, the internal flow path 26 is configured as a flow path bent in a U shape from the first opening 26A toward the second opening 26B. That is, all the internal flow paths 26 are arranged in parallel in one membrane leaf 23, and the first openings and the second openings are alternately arranged in the axial direction of the central tube 3.

  The joint portions 27 to 29 are extended toward the outer peripheral surface of the central tube 3 and divide the cylindrical flow path 20C. Thus, the first opening 26A and the second opening 26B are isolated from each other.

  The plurality of communication holes 37 arranged in the axial direction of the central tube 3 described above are connected to the first opening 26A via the cylindrical flow path 20C, and the communication hole 37 is connected to the supply hole 35, the second opening 26B, and the cylindrical flow path. A communication hole 37 that communicates via 20 </ b> C includes a recovery hole 36. Actually, a plurality of supply holes 35 and a plurality of recovery holes 36 communicate with each of the first opening 26A and the second opening 26B, but only one is shown in FIG.

  In the central tube 3, the interior of the central tube 3 is partitioned in the axial direction between the supply hole 35 and the recovery hole 36 for each of the plurality of internal flow paths 26 arranged in the axial direction of the central tube 3. Partition walls 31 and 32 are provided. Of these plurality of partition walls, the terminal partition wall 32 located closest to the outflow port 34 completely blocks the inside of the central tube 3. A through hole 38 is formed in the partition wall 31 other than the terminal partition wall. The through hole 38 is provided at the center of the partition wall 31 and has a circular shape centered on the center of the partition wall 31.

  Next, the flow of the first liquid to be concentrated in the central tube 3 and the internal flow path 26 of the membrane leaf 23 will be described with reference to FIG.

  The arrows in FIG. 3 schematically show the flow of the first liquid flowing through the spiral forward osmosis membrane element 2. The first liquid supplied to the forward osmosis membrane module 1 flows into the inlet 33 of the center tube 3 via the center supply tube 7A. A part of the first liquid that has flowed into the inflow port 33 enters the upstream internal flow channel 26 from the first opening 26 </ b> A via the supply hole 35 and the cylindrical flow channel 20 </ b> C, and flows through the internal flow channel 26. The second liquid (liquid to be diluted) supplied from the peripheral supply pipe 8A flows outside the membrane leaf 23, and the first liquid and the second liquid flow on both surfaces of the forward osmosis membrane 21 of the membrane leaf 23. ing. Accordingly, a part of the first liquid flowing in the internal flow path 26 of the membrane leaf 23 moves to the outside of the membrane leaf 23 through the forward osmosis membrane 21 due to the osmosis phenomenon. Then, the first liquid that has not moved from the internal flow path 26 on the upstream side of the membrane leaf 23 to the outside of the membrane leaf 23 exits the second opening 26B of the internal flow path 26 on the upstream side, and the cylindrical flow path 20C. And it returns to the inside of the central tube 3 through the recovery hole 36.

  The other part of the first liquid that has flowed into the inflow port 33 does not flow through the upstream internal flow path 26 but flows downstream through the through hole 38 provided in the partition wall 31, and the upstream internal flow path The flow of the first liquid that has returned from 26 to the central tube 3 through the recovery hole 36 is merged. And the flow of the joined 1st liquid flows further toward the downstream. Since the end partition wall 32 completely blocks the inside of the central tube 3, the flow of the merged first liquid flows through the downstream supply hole 35 and the cylindrical flow channel 20 </ b> C to the downstream internal channel 26. Flowing. In order to dilute the second liquid flowing outside the membrane leaf 23, a part of the first liquid flowing in the downstream internal flow path 26 moves to the outside of the membrane leaf 23 via the forward osmosis membrane 21.

  The first liquid that has not moved from the internal flow path 26 on the downstream side of the membrane leaf 23 to the outside of the membrane leaf 23 exits the second opening 26B, passes through the cylindrical flow path 20C, and the collection hole 36 on the downstream side, It returns to the center pipe 3 and flows out from the outlet 34.

  Next, the effect of the spiral forward osmosis membrane element 2 of the present embodiment will be described with reference to FIGS. 3 and 5. FIG. 5 shows a spiral forward osmosis membrane element 4 as a reference example. In addition, unless specifically required, portions corresponding to the spiral forward osmosis membrane element 2 of the present embodiment of the reference example are denoted by the same reference numerals.

  The spiral type forward osmosis membrane element 4 is implemented in that both the partition wall 39A and the terminal partition wall 39B other than the terminal partition wall provided inside the center tube 3 completely block the inside of the center tube 3. It differs from the form. In the reference example, all of the liquid flowing into the inflow port 33 passes through all the internal flow paths 26 arranged in the axial direction of the central tube 3. That is, the liquid flowing in from the inflow port 33 flows in series in all the internal flow paths 26 arranged in the axial direction of the central tube 3 and flows out from the outflow port 34. Since the internal channel 26 is a channel having a relatively long bent channel length, in the reference example, the pressure loss of the liquid flow from the inlet 33 to the outlet 34 is large.

  On the other hand, in the present embodiment, since the through holes 38 are provided in the partition walls 31 other than the terminal partition wall 32, the supply that communicates with the internal channel 26 on the upstream side and the first opening 26A of the internal channel on the downstream side. All of the holes 35 communicate with the inlet 33 of the center tube 3 inside the center tube 3. Accordingly, the first liquid that flows into the inlet 33 and is closer to the inlet 33 than the partition wall 31 can flow in parallel through the plurality of internal flow paths 26 aligned in the axial direction of the central tube 3. Accordingly, in this embodiment, the pressure loss of the flow of the first liquid from the inlet 33 to the outlet 34 is reduced as compared with the reference example.

(Second Embodiment)
Next, the spiral forward osmosis membrane element 2 of the second embodiment will be described with reference to FIG. Unless otherwise required, the same reference numerals as those in the first embodiment are given. The description will focus on the parts that differ from the first embodiment.

  As shown in FIG. 4, three internal flow paths 26 are arranged in the axial direction of the central tube 21 in the membrane leaf 23 of the spiral forward osmosis membrane element 2 of the second embodiment. Accordingly, a supply hole 35 and a recovery hole 36 are provided in the central tube 3 so as to correspond to the three internal flow paths 26. The central tube 3 has a partition wall 31A and 31B other than the terminal partition wall 32 and the two terminal partition walls. The partition walls 31A and 31B other than the two terminal partition walls are provided with through holes 38A and 38B, respectively. Accordingly, a part of the first liquid that has flowed in flows through the through holes 38A and 38B to the downstream side without passing through the internal flow path 26, and thus reaches the outlet 34 from the inlet 33 as in the first embodiment. The pressure loss of the first liquid flow is reduced.

  In the partition walls 31A and 31B of the central tube 3, the opening areas of the through holes are different. The opening area of the through hole is larger in the partition wall 31A located closer to the inflow port 33 than in the partition wall 31B. The pressure of the flow of the first liquid from the inlet 33 to the outlet 34 is increased by increasing the opening area of the through hole 31A on the upstream side and increasing the amount of liquid flowing downstream without passing through the internal flow path 26. Loss is further reduced. Further, the opening area of the through hole 38B of the partition wall 31B on the downstream side is made smaller than the opening area of the through hole 38A of the partition wall 31A, thereby suppressing the shortage of the first liquid flowing into the internal flow path 26. Yes.

(Other embodiments)
The spiral forward osmosis membrane element and forward osmosis module of the present invention are not limited to the above-described embodiments, and various embodiments can be employed.

  In the present embodiment, the first liquid having a higher solute concentration than the second liquid flows into the central tube 3 of the spiral forward osmosis membrane element 2, but the second liquid to be diluted in the central tube 3 It may be inflow. In this case, in the forward osmosis membrane module 1, the amount of liquid discharged from the center discharge pipe 7B is larger than the amount of liquid supplied to the center supply pipe 7A.

  In the spiral forward osmosis membrane element 2 of the present embodiment, the end member 5 may be omitted.

  In the present embodiment, the number of the internal flow paths arranged in the axial direction of the central tube 3 and the number of partition walls 31 and 32 of the central tube 3 is two or three, but is not limited thereto. It is good also as having four or more internal flow paths and four or more partition walls.

  In the present embodiment, the through holes 38 are formed in all the partition walls 31 other than the terminal partition wall 32, but the present invention is not limited to this. When a plurality of partition walls 31 other than the terminal partition wall 32 are provided in the central tube 3, it is only necessary that a through hole 38 is formed in at least one of the plurality of partition walls 31. 3 The inside may be shut off. With such a configuration, it is possible to reduce the pressure loss of the flow of the liquid supplied to the central tube 3. In addition, it is preferable that a through hole 38 is formed in the partition wall 31 located closest to the inlet 33 among the plurality of partition walls 31 from the viewpoint of reducing pressure loss. Further, it is preferable that through holes 38 are formed in all of the plurality of partition walls 31 other than the terminal partition wall from the viewpoint of reducing pressure loss.

  In the present embodiment, the number of the communication holes 37 extending in the axial direction of the central tube 3 is two, but the present invention is not limited to this. Three or more rows of communication holes 37 may be provided so as to be evenly arranged in the circumferential direction of the tube wall of the central tube 3. By increasing the rows of the communication holes 37 extending in the axial direction of the central tube 3, it is facilitated to uniformly guide the first liquid to the internal channels 26 of the plurality of membrane leaves 23 surrounding the central tube 3.

  The size of the through hole 38 is not particularly limited. In order to sufficiently reduce the pressure loss of the flow of the first liquid from the inflow port 33 to the outflow port 34 and to suppress the amount of the first liquid flowing to the internal flow path 26 from being insufficient, You may adjust the magnitude | size of the hole 38 suitably.

  The shape of the through hole 38 is not limited to a circle, and may be an ellipse or a rectangle.

  The position where the through hole 38 is provided is not limited to the central portion of the partition wall 31. For example, an annular through hole may be provided between the center of the partition wall 31 and the outer peripheral end of the partition wall. Or you may make it provide a some through-hole about the whole partition 31 or a part.

DESCRIPTION OF SYMBOLS 1 Forward osmosis membrane module 2 Spiral type forward osmosis membrane element 23 Membrane leaf 26 Internal flow path 26A 1st opening 26B 2nd opening 3 Center pipe
31 Bulkhead 32 Terminal bulkhead
33 Inlet 34 Outlet 35 Supply hole 36 Recovery hole 38 Through hole 9A Pressure vessel

Claims (7)

A membrane leaf provided with a plurality of internal flow paths bent in parallel from the first opening toward the second opening;
A central tube around which the membrane leaf is wound, an inlet at one end, an outlet at the other end, a supply hole communicating with the first opening, and a recovery hole communicating with the second opening;
A plurality of partition walls provided in the central tube so as to be positioned between the supply hole and the recovery hole for each of the plurality of internal flow paths;
Of the plurality of partition walls, a terminal partition wall closest to the outflow port blocks the inside of the central tube, and at least one partition wall other than the terminal partition wall has a through hole formed therein. Type forward osmosis membrane element.   The spiral forward osmosis membrane element according to claim 1, wherein a through hole is formed in a partition wall closest to the inflow port among the plurality of partition walls.   The spiral forward osmosis membrane element according to claim 2, wherein through-holes are formed in all of the partition walls other than the terminal partition wall. The spiral forward osmosis membrane element is to be supplied with a first liquid to be concentrated and a second liquid to be diluted;
The spiral forward osmosis membrane element according to any one of claims 1 to 3, wherein the first liquid flows into the central tube through the inlet.   The spiral type forward osmosis membrane element according to any one of claims 1 to 4, wherein the through hole is formed at a center of the partition wall.   6. The spiral forward osmosis according to claim 1, wherein a partition wall other than the terminal partition wall is configured such that an opening area of the through hole increases as a distance from the inflow port decreases. Membrane element. A tubular pressure vessel;
A forward osmosis membrane module comprising the spiral forward osmosis membrane element according to any one of claims 1 to 6, which is loaded in the pressure vessel.

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