WO2011102443A1

WO2011102443A1 - Water treatment device

Info

Publication number: WO2011102443A1
Application number: PCT/JP2011/053450
Authority: WO
Inventors: 穣森田; 光太郎北村
Original assignee: 株式会社日立プラントテクノロジー
Priority date: 2010-02-22
Filing date: 2011-02-18
Publication date: 2011-08-25
Also published as: JP2011167669A

Abstract

Disclosed is a water treatment device which improves and stabilises the treatment performance of a reverse osmosis membrane housed in a container. In the water treatment device (10), sea water that flows in from the discharge outlet (46) of a pipe (42) is made to flow radially in the radial direction of the container (24), thereby temporarily eliminating the inflow direction component of the sea water in relation to the inlet end surface (28A) of the reverse osmosis membrane (28) Subsequently, the sea water flows in the axial direction of the container (24). During this interval, the axial-direction flow speed component of the sea water flowing in the axial direction is substantially equalized over the entire inlet end surface (28A) of the reverse osmosis membrane (28). Thus, the entire surface of the reverse osmosis membrane (28) is efficiently exposed to the sea water, thereby improving the treatment performance of the reverse osmosis membrane (28).

Description

Water treatment equipment

The present invention relates to a water treatment apparatus, and more particularly to a water treatment apparatus that treats seawater into fresh water using a reverse osmosis membrane (hereinafter referred to as RO (Reverse Osmosis) membrane).

In a conventional desalination apparatus using an RO membrane, in order to utilize reverse osmosis pressure, as in Patent Document 1, a RO membrane is filled in a cylindrically configured vessel. The seawater to be desalted flows into the vessel from the discharge port of the seawater supply piping (hereinafter referred to as piping) connected to the end of the vessel. In the case of a general desalination apparatus, the diameter of the piping is Since it is significantly smaller than the inner diameter, a rapidly expanding flow of seawater is formed in the vessel. Further, when the RO membrane is filled in the vessel, the distance between the discharge port of the pipe and the inlet end surface of the RO membrane is set to be sufficiently short from the viewpoint of improving the installation efficiency. For these reasons, a short suddenly expanding flow of the seawater running section is formed between the discharge port of the pipe and the inlet end surface of the RO membrane. Thereby, seawater collides with the approximate center part of the inlet end surface of the RO membrane and flows into the RO membrane without decelerating from the discharge port. That is, in the water treatment apparatus of Patent Document 1, the inflow direction of seawater is set in a direction perpendicular to the inlet end surface of the RO membrane.

Seawater that has flowed into the RO membrane is desalted by permeating the RO membrane, and the desalted permeated water penetrates into the core tube disposed at the center of the RO membrane and passes from the core tube to the outside of the vessel. It is taken out.

As the RO membrane, a spiral membrane in which a filtration membrane and a mesh-like support are overlapped and closed in a bag shape and wound in a roll cake shape around a core tube is known (for example, Patent Document 2). A membrane using a large number of hollow fiber membranes is also well known. Further, in the vessel, the pressure applied to the seawater is 5 MPa or more, and the vessel is composed of a high-pressure vessel made of stainless steel or the like so as to withstand this pressure.

Special table 2008-534271 gazette Special table 2008-534270

As described above, in the water treatment apparatus disclosed in Patent Document 1, the suddenly expanding flow of seawater collides with the vicinity of the substantially central portion of the RO membrane inlet end surface inside the vessel. For this reason, the flow of seawater that moves in the RO membrane also moves in the vicinity of the axial center. Therefore, in the water treatment apparatus of Patent Document 1, only the vicinity of the center of the RO membrane is mainly used, and there is a problem that the entire area (area) of the RO membrane cannot be used effectively. Moreover, in the water treatment apparatus of patent document 1, since only the limited membrane surface used is contaminated early and clogging progresses, the seawater pressurization pressure (permeated water suction pressure) increases in a short time. . Due to this problem, the water treatment apparatus of Patent Document 1 has a problem that the operation of the apparatus tends to become unstable.

Incidentally, in the water treatment apparatus of Patent Document 1, a flow distribution plate is provided on the inlet end face of the RO membrane. However, since this flow distribution plate has many holes formed in the inflow direction of the seawater, it is inevitable that the seawater hits the inlet end face of the RO membrane perpendicularly. For efficient desalination of seawater, it is ideal that seawater permeates radially from the outer surface of the RO membrane.

On the other hand, even when the water treatment apparatus is enlarged, that is, when the vessel has a large diameter, it is unrealistic to increase the diameter of the pipe according to the expansion ratio of the vessel. In other words, there are technical and construction limitations in increasing the diameter of the pipes because auxiliary parts such as elbow pipes and bellbs are provided in the middle of the pipes from the seawater tank to the vessel. Moreover, since such a pipe is a pressure tube, it is expensive, and if the pipe is made large in diameter, the price of the apparatus increases and the cost is unrealistic.

This invention is made in view of such a situation, and it aims at providing the water treatment apparatus which can improve the processing performance of RO membrane with which the container was filled.

The present invention includes a cylindrical container to which water to be treated is supplied, an RO membrane that fills the cylindrical container and processes the supplied water to be treated, and is connected to an end surface of the container to the container. A water treatment apparatus comprising: a pipe for supplying water to be treated; and a rectifying member that is provided at a discharge port of the pipe and diffuses the water to be treated flowing from the discharge port into the container in a radial direction of the container. provide.

The problem with the conventional water treatment apparatus is that the ratio of the diameter of the discharge port of the pipe to the inner diameter of the container is large, and due to this large ratio, a jet is generated immediately after the discharge port. Due to the short distance from the inlet end surface of the RO membrane, the water to be treated collides with the inlet end surface of the RO membrane in the vertical direction in a state where the flow velocity component of the treated water is not attenuated.

The water to be treated that has collided with the inlet end face of the RO membrane moves to the downstream portion of the RO membrane as it is, while the permeated water permeates into the membrane from the surface of the RO membrane. When the water to be treated moves through the RO membrane, if the RO membrane is a spiral RO membrane, a flow velocity component is generated not only in the axial direction of the container but also in the circumferential direction due to the characteristics of the structure. For this reason, from the entrance to the exit of the RO membrane, the water to be treated that has collided only near the axial center on the entrance end surface of the RO membrane is also dispersed in the circumferential direction of the container. However, since the spiral RO membrane has a structure like a narrow channel in which filtration membrane bodies are wound in multiple layers, movement of the container in the radial direction is small. For this reason, if the collision area of to-be-processed water in the entrance end surface of RO membrane is small, the area | region where to-be-processed water flows will be limited to a narrow range, and the malfunction mentioned above will generate | occur | produce.

Therefore, in the present invention, the inflow direction component of the water to be treated with respect to the RO membrane inlet end face is immediately attenuated in the container, so that the flow velocity distribution of the water to be treated when colliding with the RO membrane inlet end face is uniform over the entire inlet end face. Or a rectifying member that is biased toward the outer peripheral side of the inlet end face.

The specific rectifying member changes the flow direction of the water to be treated flowing into the container from the discharge port of the pipe to the radial direction of the container. Thereby, the to-be-processed water which flowed in in the container flows toward the inner peripheral surface of the container after being diffused in the radial direction. The flow velocity distribution of this flow is substantially uniform with respect to the axial direction of the flow, or is biased toward the outer peripheral side of the RO membrane. Therefore, due to the action of this rectifying member, the flow velocity distribution at the time of collision with the RO membrane inlet end surface becomes substantially uniform over the entire inlet end surface, or is biased toward the outer peripheral side of the RO membrane, thereby improving the RO membrane processing performance.

One aspect of the rectifying member is a cylindrical container having a bottom and having an outlet on the outer peripheral surface thereof. The water to be treated that flows in from the discharge port of the pipe collides with the bottom of the cylindrical container and diffuses in the radial direction of the container from the outlet.

Also, one mode of the rectifying member is a guide member having a conical guide surface. The treated water flowing from the discharge port of the pipe is diffused in the radial direction of the container by the guide surface of the guide member.

The present invention is suitable for a water treatment apparatus for desalinating seawater.

According to the water treatment device of the present invention, since the flow direction of the water to be treated flowing into the container from the discharge port of the pipe can be changed to the radial direction of the container, Can collide uniformly, or a high flow velocity distribution can be generated in the outer peripheral portion of the inlet end face. As a result, according to the present invention, the water to be treated can permeate substantially the entire area of the RO membrane, so that the treatment performance of the RO membrane is improved.

According to the present invention, the surface of the RO membrane is uniformly exposed to the water to be treated, and only a part of the membrane surface is not exposed. For this reason, efficient water treatment operation by the RO membrane becomes possible. In addition, the uniform exposure to such a film surface causes the occurrence of fouling to progress uniformly and gradually, thereby reducing the occlusion time due to fouling.

FIG. 1 is a block diagram of a seawater desalination treatment system in which a water treatment apparatus according to an embodiment is installed; FIG. 2 is a perspective view showing the configuration of the elements of the water treatment device of the embodiment; 3 is a perspective view of a module in which the element shown in FIG. 2 is incorporated in a vessel; 4 is a front view of the element showing a state before the RO membrane of the element shown in FIG. 2 is wound; FIG. 5 is a front view of the element shown in FIG. 2; FIG. 6 is a side sectional view showing a part of the module shown in FIG. FIG. 7 is a perspective view showing the configuration of the rectifying member of the first aspect; FIG. 8 is an explanatory view showing an example of the flow velocity distribution of seawater generated by the rectifying member; FIG. 9 is an explanatory view showing an example of the flow velocity distribution of seawater generated by the rectifying member; FIG. 10 is an explanatory view showing the configuration of the rectifying member of the second aspect.

Hereinafter, preferred embodiments of the water treatment apparatus according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a seawater desalination treatment system 20 in which a water treatment apparatus 10 according to an embodiment is incorporated.

A seawater desalination treatment system 20 shown in FIG. 1 includes a tank 12 in which seawater is stored, a high-pressure pump 14, and a water treatment device 10. Seawater in the tank 12 is supplied to the water treatment device 10 at a high pressure by the high pressure pump 14, and desalted by reverse osmosis treatment (desalination treatment) by an RO membrane (treatment membrane) described later of the water treatment device 10. The permeated water 16 is separated into the concentrated water 18 having a concentrated salt content. The permeated water 16 thus obtained is sent to the outside of the water treatment device 10. In the seawater desalination treatment system 20 according to the embodiment, seawater is supplied to the water treatment apparatus 10 at a high pressure by the high pressure pump 14. A high pressure suction pump is connected to the permeate outlet side of the water treatment apparatus 10. The seawater may be introduced into the water treatment apparatus 10 from the tank 12 by this suction pump. Moreover, you may provide both the high-pressure pump 14 and a suction pump.

As the seawater in the tank 12, raw seawater may be used as it is, but it is preferable to use seawater that has been pretreated to remove turbid components contained in the raw seawater. Examples of pretreatment include use of a filter, introduction of raw seawater into a sedimentation basin, addition of a sterilizing agent such as chlorine, precipitation removal of particles in the raw seawater, and sterilization of microorganisms. Further, seawater obtained by adding a flocculant such as iron chloride to the raw seawater to aggregate the turbid component and filtering it off may be used.

The water treatment apparatus 10 connects one or a plurality of elements 22 shown in FIG. 2 in series, fills the container 24 shown in FIG. 3 into a module 26, and connects the module 26 alone or in parallel. It is constituted by doing. A predetermined operating pressure is applied to the module 26 by the high-pressure pump 14. 3 shows a module 26 in which three

elements

22, 22... Are connected in series, the number of elements 22 is not limited to three. The container 24 is made of super stainless steel (a steel type having a PREN value (pitting corrosion coefficient) of 40 or more) so as to withstand high pressure (5 MPa or more).

As shown in FIG. 2, the element 22 includes an RO membrane unit 32 including an RO membrane 28 and a treated water pipe 30 arranged around a water collection pipe 34. As shown in FIG. 4, the RO membrane unit 32 has four bag-

like RO membranes

28, 28... Radially connected to the outer periphery of the water collecting pipe 34. These RO membranes 28, 28. It is constituted by winding around the water collecting pipe 34 in a spiral shape. One end of the bag-like RO membrane 28 is opened, and the RO membrane 28 is bonded to the water collection tube 34 so that the opening communicates with the through hole 36 of the water collection tube 34 shown in FIG. Seawater, which is the water to be treated, flows through the outer surface of the RO membrane 28 and is desalted by passing through the RO membrane 28. Then, the desalted permeated water that has passed through the RO membrane 28 is collected from the inside of the RO membrane 28 into the water collecting pipe 34 through the opening of the RO membrane 28 and the through hole 36 of the water collecting pipe 34, and the water collecting pipe 34 is discharged from the element 22 through the treated water pipe 30. Note that reference numeral 38 in FIG. 4 is a mesh spacer disposed inside the RO membrane 28. The spacer 38 holds the RO membrane 28 so that the inner space of the RO membrane 28 is not crushed even if the RO membrane 28 is wound in a spiral shape. Reference numeral 40 denotes a mesh-like spacer disposed between the

adjacent RO membranes

28 and 28. The spacers 40 are also radially bonded to the outer periphery of the water collecting pipe 34 in the same manner as the RO membrane 28.

As shown in FIG. 3, a pipe 42 is connected to the end face on one end side of the container 24. Seawater is supplied by the high-pressure pump 14 from the tank 12 of FIG.

The pipe 42 is connected to a lid 48 that closes the opening on one end side of the container 24 in the side sectional view of the module 26 shown in FIG. 6 and the perspective view shown in FIG. The pipe 42 is connected to the lid 48 so that the axis a of the pipe 42 is coaxial with or parallel to the central axis b of the container 24. Further, the discharge port 46 of the pipe 42 is formed on the same surface as the inner surface of the lid 48.

The seawater supplied into the container 24 from the discharge port 46 of the pipe 42 is guided to the RO membrane unit 32 of the element 22 through a rectifying member 50 described later, and sequentially passes through the

RO membranes

28, 28. Thus, the water is collected in the water collecting pipe 34 and taken out from the treated water pipe 30 to the outside of the module 26. Further, the concentrated water that has not permeated through the

RO membranes

28, 28... Is sequentially guided to the

downstream elements

22, 22, and is separated into permeated water and concentrated water in the same manner as described above, and finally the concentrated water is discharged. It is discharged from the tube 44 to the outside of the module 26. The concentrated water discharge pipe 44 is connected to the outer peripheral portion on the other end side of the container 24.

By the way, in the water treatment apparatus 10 of the embodiment, the module 26 is provided with a seawater rectifying member 50.

The rectifying member 50 diffuses seawater flowing into the container 24 from the discharge port 46 of the pipe 42 in the radial direction of the container 24, and is fixed to the inner surface of the lid 48.

The first mode of the rectifying member 50 is a cylindrical container having a bottom and provided with a plurality of

outlets

52, 52. The rectifying member 50 is fixed to the lid 48 so that the axis c of the rectifying member 50 is coaxial with the axis a of the pipe 42, and the bottom 54 of the rectifying member 50 is the discharge port 46 of the pipe 42 as shown in the perspective view of FIG. 7. Are arranged opposite to each other. Therefore, the seawater flowing into the container 24 from the discharge port 46 of the pipe 42 collides with the bottom 54 of the rectifying member 50 and diffuses in the radial direction of the container 24 from the

outlets

52, 52.

By the way, in the water treatment apparatus of Patent Document 1, seawater flowing in from the discharge port of the pipe enters the RO membrane inlet end face in a jet state without the flow velocity being attenuated. At this time, since the run-up section between the RO membrane inlet end face and the piping outlet is short, the seawater flowing from the outlet does not spread in the radial direction in the container and has a high flow velocity axial component. While maintaining, it collides with the entrance end face of the RO membrane and enters the RO membrane. Due to this action, the water treatment apparatus of Patent Document 1 cannot improve the treatment performance of the RO membrane.

Next, the operation of the water treatment apparatus 10 according to the embodiment configured as described above will be described.

In the water treatment apparatus 10 according to the embodiment, since the rectifying member 50 is provided, the flow velocity distribution as in the water treatment apparatus of Patent Document 1 is between the discharge port 46 of the pipe 42 and the inlet end surface 28A of the RO membrane 28. Does not occur.

FIG. 8 shows the flow velocity distribution of seawater with respect to the inlet end surface 28A of the RO membrane 28 of the water treatment device 10 of the embodiment by arrows.

In this water treatment apparatus 10, since the rectifying member 50 is provided, seawater flowing into the container 24 from the discharge port 46 of the pipe 42 collides with the bottom 54 of the rectifying member 50 and is discharged from the

outlets

52, 52. 24 diffuses in the radial direction.

Thereby, since the seawater that has flowed into the container 24 flows radially toward the inner peripheral surface of the container 24, the inflow direction component with respect to the inlet end surface 28 </ b> A of the RO membrane 28 is small. Disappears or significantly attenuates while flowing toward the inner peripheral surface 24B. Then, the seawater collides with the inner peripheral surface 24B of the container 24 and becomes a flow in which the axis b direction is mainstream in the container 24. During this time, the seawater flowing out from the

respective outlets

52, 52... Interacts with the seawater fluid so that the flow velocity distribution of the seawater in the direction of the axis b is substantially uniform in the direction of the axis b, or the RO membrane 28. It is biased toward the outer peripheral side. Therefore, due to the action of the rectifying member 50, the flow velocity distribution when colliding with the inlet end face 28A of the RO membrane 28 becomes substantially uniform over the entire inlet end face 28A, or the flow velocity distribution becomes the outer periphery of the RO membrane 28 as shown in FIG. Since it is biased to the side, the processing performance of the RO membrane 28 is improved.

FIG. 10 shows a second mode of the rectifying member 60.

The rectifying member 60 has a substantially conical shape. The rectifying member 60 is arranged such that the axis a of the pipe 42 and the axis d thereof are coaxially arranged, and the top portion 60 </ b> A is opposed to the discharge port 46 with a predetermined distance therebetween. The rectifying member 60 is fixed to the pipe 42 by a fixing member 68 including a screw rod 62, a nut 64, and a holding member 66. The fixing part of the rectifying member 60 may be the lid 48.

The seawater flowing from the discharge port 46 of the pipe 42 is diffused in the radial direction of the container 24 by the inclined conical surface (guide surface) 60B of the rectifying member 60. Since the subsequent operation is the same as that of the rectifying member 50, the description thereof is omitted here. Although the flow regulating member 60 is configured in a conical shape, the shape is not limited to this, and the shape is provided with a guide surface that can diffuse seawater flowing from the discharge port 46 of the pipe 42 in the radial direction of the container 24. I just need it. For example, a plate material whose surface faces the discharge port 46 may be used. The surface of the plate material becomes the guide surface.

As described above, seawater is sufficiently exposed to the entire surface of the RO membrane 28 at the inlet end surface 28A of the RO membrane 28 by the action of the rectifying

members

50 and 60, and moves toward the inside of the element 22 and the outlet as it is. For this reason, the entire surface of the RO membrane 28 is efficiently exposed to seawater. As a result, the occurrence of fouling of the RO film 28 progresses uniformly and gradually, so that the blocking time due to fouling can be reduced.

Therefore, according to the water treatment device 10 of the embodiment, the treatment performance of the RO membrane 28 is improved as compared with the water treatment device of Patent Document 1.

Such a water treatment apparatus 10 has a high ratio (enlargement ratio) between the diameter φ1 of the discharge port 46 of the pipe 42 and the inner diameter φ2 of the vessel 24 in FIG. 6, and the inlet end surface 28A of the discharge port 46 and the RO membrane 28. This is effective when the distance L is short. For example, the inner diameter φ2 of the container 24 is 5 to 10 times the diameter φ1 of the discharge port 46, and the distance L is not more than five times the inner diameter φ2 of the container 24.

In the embodiment, the water treatment apparatus that desalinates seawater using the RO membrane has been described, but the membrane is not limited to the RO membrane, and a hollow fiber membrane may be applied. That is, the configuration of the present invention can be applied to any apparatus that uses a membrane to treat water to be treated. In addition, the water to be treated is not limited to seawater, and it may be a water treatment device that removes dissolved substances, turbidity, microorganisms, etc. in tap water using membranes such as RO membranes and hollow fiber membranes. The configuration of the present invention can be applied.

DESCRIPTION OF SYMBOLS 10 ... Water treatment apparatus, 12 ... Tank, 14 ... High pressure pump, 16 ... Permeated water, 18 ... Concentrated water, 20 ... Seawater desalination processing system, 22 ... Element, 24 ... Container, 26 ... Module, 28 ... RO membrane, 30 ... treated water pipe, 32 ... RO membrane unit, 34 ... water collecting pipe, 36 ... through hole, 38 ... spacer, 40 ... spacer, 42 ... piping, 44 ... concentrated water discharge pipe, 46 ... discharge port, 48 ... lid, 50 ... rectifying member, 52 ... outlet, 54 ... bottom, 60 ... rectifying member, 62 ... screw rod, 64 ... nut, 66 ..., holding member, 68 ... fixing member

Claims

A cylindrical container to which the water to be treated is supplied;
RO membrane filled in the cylindrical container and treating the supplied treated water;
A pipe connected to the end face of the container for supplying the treated water to the container;
A rectifying member that is provided at a discharge port of the pipe and diffuses the water to be treated flowing from the discharge port into the container in a radial direction of the container;
A water treatment apparatus comprising:
The rectifying member is a cylindrical container having an outlet on the outer peripheral surface,
The water treatment apparatus according to claim 1, wherein the water to be treated that flows in from the discharge port of the pipe collides with a bottom portion of the cylindrical container and diffuses in the radial direction of the container from the outlet.
The rectifying member is a substantially conical guide member,
The water treatment apparatus according to claim 1, wherein the water to be treated which flows from the discharge port of the pipe is diffused in the radial direction of the container by the guide member.