WO2011102464A1

WO2011102464A1 - Water processing device

Info

Publication number: WO2011102464A1
Application number: PCT/JP2011/053506
Authority: WO
Inventors: 穣森田; 盛典富樫; 修大塚田
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: JP2011167668A

Abstract

Disclosed is a water processing device (10) comprised of a reverse osmosis membrane (28), a cylindrical container (24) with the reverse osmosis membrane (28) housed therein, and a supply pipe (42) for the water processing device connected to outer surface of the container (24) such that it is tangential to the inner surface of the container (24). This embodiment allows the whole face of the reverse osmosis membrane (28) to be efficiently exposed to the water for treatment, which improves 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 water to be treated using a membrane.

In a conventional desalination apparatus using a reverse osmosis membrane (hereinafter referred to as RO (Reverse Osmosis) membrane) as a membrane, reverse osmotic pressure is used. Therefore, as in Patent Document 1, RO is placed in a cylindrical vessel. The membrane is filled. 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.

In one aspect of the present invention, in order to achieve the above object, an RO membrane for treating water to be treated, a cylindrical container filled with the RO membrane, and an inner peripheral surface of the container on an outer peripheral surface of the container Provided is a water treatment apparatus including a pipe for supplying the water to be treated in a tangential direction with respect to a surface.

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

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 treated water that collides with the inlet end surface of the RO membrane moves to the downstream portion of the RO membrane as it is, while the permeated water permeates into the RO 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 water treatment apparatus according to one aspect of the present invention, the water to be treated when impinging on the inlet end surface of the RO membrane is immediately attenuated in the container by the vertical component of the water flow to be treated with respect to the inlet end surface of the RO membrane. Is provided with a rectifying mechanism that can equalize the flow velocity distribution over the entire area of the inlet end face, or a rectifying mechanism that biases the flow velocity distribution toward the outer peripheral side of the inlet end face.

A specific rectifying mechanism is a mode in which piping is provided on the outer peripheral surface of the container and tangential to the inner peripheral surface of the container. As a result, the treated water that has flowed into the container becomes a swirling flow along the inner peripheral surface of the container, so that the vertical component is small, and this vertical component is generated when the treated water swirls. It disappears or attenuates significantly. Therefore, due to the action of this rectifying mechanism, the flow velocity distribution at the time of collision with the RO membrane inlet end surface becomes substantially uniform throughout the inlet end surface, or is biased toward the outer peripheral side of the RO membrane, thereby improving the RO membrane processing performance. In addition, by increasing the flow velocity of the swirl flow, a high flow velocity distribution can be generated on the outer peripheral side of the RO membrane inlet end surface. Therefore, when the RO membrane is a spiral RO membrane, the processing performance of the RO membrane is Further improvement. Here, the inner diameter of the cylindrical container is preferably not less than 5 times and not more than 10 times the diameter of the discharge port of the pipe.

According to the water treatment device of the present invention, since the water to be treated can flow along the inner peripheral surface of the container, the water to be treated uniformly collides with the entire inlet end surface of the RO membrane, or the outer peripheral portion of the inlet end surface. A high flow velocity distribution can be produced. 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 part of the RO membrane surface is not exposed. For this reason, efficient water treatment operation by the RO membrane becomes possible. In addition, by performing such uniform exposure to the RO membrane surface, the occurrence of fouling progresses uniformly and gradually, so that the occlusion time due to fouling can be reduced.

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 illustrating a configuration of elements of the water treatment apparatus according to the embodiment. FIG. 3 is a perspective view of a module in which the element shown in FIG. 2 is incorporated in a container. FIG. 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. FIG. 6 is a side cross-sectional view showing a part of the module shown in FIG. FIG. 7A is a cross-sectional view of the module of FIG. 6 taken along line 7-7. FIG. 7B is a perspective view of a main part of the module of FIG. FIG. 8 is an explanatory diagram showing an example of the flow velocity distribution of seawater generated by the rectifying mechanism. FIG. 9 is an explanatory view showing an example of the flow velocity distribution of seawater generated by the rectifying mechanism.

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 reverse osmosis treatment (desalination treatment) is performed by an RO membrane (to be described later) of the water treatment device 10, thereby desalted permeated water 16. And concentrated water 18 in which the salinity is concentrated. 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) (Pitting Resistance Equivalent Number) 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 outer peripheral portion on one end side of the container 24. Seawater is supplied by the high-pressure pump 14 from the tank 12 of FIG. The seawater supplied into the container 24 is guided to the RO membrane unit 32 of the element 22 and sequentially passes through the

RO membranes

28, 28..., And then collected in the water collecting pipe 34 as described above and from the treated water pipe 30 to the module 26. It is taken out outside. 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.

Incidentally, in the water treatment apparatus 10 of the embodiment, the module 26 is provided with a seawater rectification structure.

This rectifying structure is configured by providing a pipe 42 on the outer peripheral surface 24A of the container 24 in the cross-sectional view of the side surface of the module 26 shown in FIG. The pipe 42 is arranged in a direction in which the axis a of the pipe 42 is orthogonal to the long axis b of the container 24. The pipe 42 is connected to the outer peripheral surface 24A of the container 24 in a posture in which the axis a is oriented in a tangential direction with respect to the inner peripheral surface 24B of the container 24 in the cross-sectional view of the module 26 shown in FIG. 7A. Has been. Further, as shown in the perspective view of FIG. 7B, the discharge port 46 of the pipe 42 is formed flush with the inner peripheral surface 24 </ b> B of the container 24.

Therefore, the seawater injected from the discharge port 46 of the pipe 42 flows in the container 24 as a swirl flow along the inner peripheral surface 24B of the container 24 as shown by the arrow in FIG. 7A, and the

RO membranes

28, 28. To the inlet end face 28A (same as the inlet end face of the element 22).

By the way, in the water treatment device of Patent Document 1, seawater injected 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 surface and the piping outlet is short, the seawater injected 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 of the embodiment, the pipe 42 is provided on the outer peripheral surface 24A of the container 24, and the axis a of the pipe 42 is provided in the tangential direction with respect to the inner peripheral surface 24B of the container 24. The flow velocity distribution as in the water treatment apparatus of Document 1 does not occur between the discharge port 46 of the pipe 42 and the inlet end surface 28A of the RO membrane 28.

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, the pipe 42 is provided on the outer peripheral surface of the container 24 and is provided in a tangential direction with respect to the inner peripheral surface 24 </ b> B of the container 24. It becomes a swirl flow along the inner peripheral surface 24B. For this reason, the vertical component of the seawater flow with respect to the inlet end surface 28A of the RO membrane 28 once disappears. Thereafter, the seawater moves in the axial direction of the container 24 while turning along the inner peripheral surface 24 </ b> B of the container 24. During this time, the axial component of the flow velocity in the axial direction of the seawater flow is substantially uniform as shown in FIG. 8, or the position near the inner peripheral surface 24B of the container 24 increases as shown in FIG. 9 when the flow velocity of the seawater is increased. .

For this reason, seawater is sufficiently exposed to the entire surface of the RO membrane 28 at the inlet end face 28A of the RO membrane 28 and moves toward the inside of the element 22 and the outlet as it is, so that the entire surface of the RO membrane 28 is efficiently obtained. 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. Note that it is preferable to set the velocity component in the outer circumferential direction of the swirling flow to 2 to 10 times the vicinity of the center from the viewpoint of improving the processing performance of the RO membrane 28.

Note that the axis a of the pipe 42 may be slightly inclined with respect to the long axis b of the container 24. Further, the flow direction of the swirl flow may be the same as the winding direction of the RO membrane 28, but by making the direction reverse, the crevice flow pressure prevents the gap between the RO membrane 28 and the RO membrane 28 from being crushed. Therefore, seawater desalination treatment by the RO membrane 28 is stabilized. Further, the pipe 42 may be provided on a lid for closing the inlet opening of the container 24.

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. That is, the configuration of the present invention can be applied to any apparatus that uses a membrane to treat water to be treated. Further, the water to be treated is not limited to seawater, and even a water treatment apparatus that uses a membrane such as an RO membrane to remove dissolved substances, turbidity, microorganisms, etc. in tap water can be used in the present invention. Configuration 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

Claims

A water treatment device,
An RO membrane for treating the water to be treated;
A cylindrical container filled with the RO membrane;
A water treatment apparatus comprising a pipe for supplying the water to be treated in a tangential direction to the inner peripheral surface of the container on the outer peripheral surface of the container.
The water treatment apparatus according to claim 1, wherein an inner diameter of the cylindrical container is not less than 5 times and not more than 10 times a diameter of a discharge port of the pipe.