JP2012130838A - Reverse osmosis treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reverse osmosis treatment apparatus constituted so as to eliminate the nonuniformity in the amount of transmitted water by regulating the pressure in a pressure container to regulate the amount of the transmitted water.SOLUTION: The reverse osmosis treatment apparatus 10 is characterized in that a plurality of reverse osmosis membrane elements 22 equipped with reverse osmosis membranes 28 are connected in series by water collection piping 34, through which the transmitted water obtained by passing water to be treated through the reverse osmosis membranes 28 flows, within the pressure container 24 equipped with an introducing pipe 56 for supplying the water to be treated, the water collection piping 34 is internally equipped with a resistor 80 for separating the transmitted water into the front stage being the supply side of the water to be treated and the rear stage being the discharge side of concentrated water, a first discharge pipe 58 for discharging the transmitted water of the front stage, a second discharge pipe 60 for discharging the transmitted water of the rear stage and a third discharge pipe 62 for discharging the concentrated water and a first valve 64 is provided to a first discharge pipe 68.

Description

  The present invention relates to a reverse osmosis treatment apparatus, and more particularly to a reverse osmosis treatment apparatus that eliminates unevenness in the amount of permeated water between an element on a supply water side and an element on a concentrated water side.

  In a desalination apparatus using a reverse osmosis membrane (hereinafter referred to as RO (Reverse Osmosis) membrane), a reverse osmosis pressure is utilized. Therefore, as shown in FIG. The RO membrane elements 122 are arranged in series, and each RO membrane element 122 is connected by a water collecting pipe 134 at the center of the RO membrane element 122. Supply water is supplied from one of the desalination treatment apparatuses by a high-pressure pump, and the inside of the pressurized container 124 is pressurized by the opening degree of a valve installed on the concentrated water side. When the pressurized pressure exceeds the osmotic pressure of the feed water, it passes through the RO membrane, and demineralized water (permeated water) flows into the central water collecting pipe 134.

  The supply water supplied into the pressurized container 124 has a salt concentration that increases from the supply water side to the concentrated water side, so that the pressure in the pressurized container 124 eventually becomes the final stage salt concentration and the amount of permeated water. The pressure to be pressurized is determined by the supply water flow velocity on the membrane surface. Accordingly, since the pressure on the supply water side in the pressurized container 124 is more than necessary, the amount of permeated water increases. For example, FIG. 12 shows the relationship between the position of the RO membrane element and the relative flux (relative flux) when seven RO membrane elements 122 are arranged in series. The element position in FIG. 12 is the number from the supply water side. As shown in FIG. 12, it can be seen that the amount of permeated water on the supply water side is large, and the amount of permeated water decreases as it goes to the concentrated water side. This is because the salt concentration of the water to be treated increases as it goes to the concentrated water side, so a high pressure is required on the concentrated water side. This is because much permeated water is generated. Thus, as shown in FIG. 12, when the amount of permeated water in the pressurized container 124 is non-uniform, the required power increases and contamination of the RO membrane element on the supply water side proceeds.

  In order to solve such a problem, for example, in Patent Document 1 below, a plug that closes the water collection pipe at the connection portion of the RO membrane element at the center in the pressurized container, and a collection closed by the plug are disclosed. There is described a seawater desalination apparatus provided with a permeate line for discharging permeate separated from a water pipe into the front and rear.

JP 2010-179264 A

  However, in the apparatus described in Patent Document 1, since the plug that closes the water collecting pipe is provided at the connection portion of each RO membrane element, further fine adjustment could not be performed. In addition, since it is provided at the connection part of each RO membrane element, when replacing the RO membrane element, the RO membrane element on the supply water side, which is most easily contaminated, is usually removed, and a new RO is placed on the concentrated water side. The replacement can be performed by adding the membrane element. However, in the apparatus described in Patent Document 1, since the position of the plug changes, it is necessary to disassemble and reattach the plug.

  This invention is made | formed in view of such a situation, The water collection piping in a pressurization container can be isolate | separated easily in arbitrary positions, and the pressure in the pressurization container before and behind the separation is adjusted. Adjust the amount of permeated water. Accordingly, it is an object of the present invention to provide a reverse osmosis treatment apparatus that can eliminate non-uniformity in the amount of permeated water of the RO membrane element and obtain a desired amount of permeated water with less power.

  According to a first aspect of the present invention, in order to achieve the above object, a plurality of reverse osmosis membrane elements including a reverse osmosis membrane are provided in a pressure vessel including an introduction pipe for supplying the water to be treated. It is connected in series by a water collecting pipe through which permeated water that has passed through the osmosis membrane flows, and in the water collecting pipe, the permeated water is supplied at the front stage that is the supply side of the treated water and the discharge side of the concentrated water. A resistor that separates into a certain rear stage, a first discharge pipe that discharges the permeate in the previous stage, a second discharge pipe that discharges the permeate in the rear stage, and a third discharge that discharges the concentrated water A reverse osmosis treatment device comprising a first valve on the first discharge pipe.

  According to claim 1, the resistor is provided in the water collecting pipe of the reverse osmosis membrane element including the reverse osmosis membrane, and the first discharge pipe and the second discharge pipe for discharging the permeated water from both sides of the resistor are provided. I have. Therefore, since the amount of permeated water in the first stage can be suppressed by the first valve, the amount of permeated water in the subsequent stage can be relatively increased, and the non-uniformity in the amount of permeated water in the reverse osmosis membrane element is eliminated as compared with the conventional one. be able to. Therefore, since the amount of permeated water can be increased with the same pressure, it is possible to save power and to prevent generation of extremely osmotic reverse osmosis membrane elements, thereby enabling long-term use.

  A second aspect of the present invention is characterized in that, in the first aspect, the resistor can be installed at an arbitrary position in the water collecting pipe.

  According to the second aspect, the flow rate can be controlled more finely by providing the resistor not at the connection portion of each reverse osmosis membrane element but at an arbitrary position in the water collecting pipe. Therefore, processing can be performed under more optimal conditions.

  A third aspect is characterized in that, in the first or second aspect, the resistor is water-impermeable.

  According to the third aspect, since the water collecting pipe can be divided by the resistor, the pressure in the water collecting pipe can be controlled with the resistor as a boundary. Therefore, the amount of permeated water can be easily adjusted.

  A fourth aspect of the present invention is characterized in that, in the first or second aspect, the resistor is water permeable.

  A fifth aspect of the present invention according to the fourth aspect is characterized in that the resistor is made of a porous material.

  A sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, a slit through which permeated water passes is formed in the resistor.

  According to the fourth to sixth aspects, the resistance body can be made water permeable, or the slit can be provided so that the permeated water can pass therethrough, so that resistance can be provided in the water collecting pipe, so that the permeated water amount is made equal. be able to.

  A seventh aspect of the present invention is characterized in that, in any one of the fourth to sixth aspects, a plurality of the resistors are provided in the water collecting pipe.

  According to the seventh aspect, by providing a plurality of resistors in the water collecting pipe, the pressure in the water collecting pipe can be adjusted more finely, so that the unevenness of the permeated water amount can be eliminated.

  According to the present invention, the permeated water is extracted from both sides of the pressure vessel, and there is a resistor in the water collecting pipe, and the position of this resistor can be moved to any location in the water collecting pipe. The pressure in the pressure vessel can be adjusted by a valve, and the amount of permeated water from both sides can be adjusted. Therefore, since the permeated water can be generated by effectively applying pressure to the RO membrane element, the cost can be reduced.

It is a block diagram of the desalination processing system in which the reverse osmosis processing apparatus of embodiment was installed. It is the perspective view which showed the structure of the element of the reverse osmosis processing apparatus of embodiment. It is the front view of the element which showed the state before RO membrane of the element shown in FIG. 2 was wound. FIG. 3 is a front view of the element shown in FIG. 2. It is sectional drawing which shows schematic structure of the reverse osmosis processing apparatus of embodiment. It is the graph which showed the relative flux of the permeated water of the reverse osmosis processing apparatus of embodiment. It is the graph which showed the relative flux of the permeated water of the reverse osmosis processing apparatus which has arrange | positioned the resistor to another position. It is the graph which showed the relative flux of the permeated water of the reverse osmosis processing apparatus which has arrange | positioned the resistor further in another position. It is sectional drawing which shows the resistor in water collection piping. It is a front view which shows the resistor in water collection piping. It is sectional drawing which shows schematic structure of the conventional reverse osmosis processing apparatus. It is the graph which showed the relationship between the position of RO membrane element of the conventional reverse osmosis processing apparatus, and the relative flux of permeate.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described with reference to the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment can be utilized. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims.

  FIG. 1 is a block diagram of a desalination treatment system 20 in which a reverse osmosis treatment apparatus 10 according to an embodiment is incorporated. In addition, the desalination processing system in this invention can be used for the system which carries out reverse osmosis processing of to-be-processed water, such as drainage reuse, pure water manufacture, brine water desalination, seawater desalination, etc., for example.

  A desalination treatment system 20 shown in the figure includes a tank 12 in which treated water is stored, a high-pressure pump 14, and a reverse osmosis treatment device 10. The water to be treated in the tank 12 is supplied to the reverse osmosis treatment device 10 by the high pressure pump 14 at a high pressure, and is subjected to reverse osmosis treatment (desalting treatment) by each RO membrane (treatment membrane) of the reverse osmosis treatment device 10. The water is separated into desalted permeated water (separated water) 16 and concentrated water (treated water) 18 in which the salt content is concentrated. The permeated water 16 thus obtained is discharged to the outside of the reverse osmosis treatment device 10 through a discharge pipe, and the concentrated water 18 is similarly discharged through a discharge pipe different from the discharge pipe for discharging the permeated water. It is discharged outside the reverse osmosis treatment apparatus 10. In addition, although the desalination processing system 20 of embodiment supplies the to-be-processed water to the reverse osmosis processing apparatus 10 with the high voltage | pressure pump 14 at high pressure, a valve is provided in the concentrated water outlet side of the reverse osmosis processing apparatus 10, The pressure in the reverse osmosis treatment apparatus 10 is set according to the opening of the valve.

  As the water to be treated in the tank 12, raw water may be used as it is, but it is preferable to use water to be treated that has been pretreated to remove turbid components contained in the raw water. Examples of the pretreatment include use of a filter and treatment of introducing raw water into a sedimentation basin and adding a bactericide such as chlorine to precipitate and remove particles in the raw water and sterilize microorganisms. In addition, water to be treated may be used by adding a flocculant such as iron chloride to raw water to agglomerate turbid components and filtering them off.

  The reverse osmosis treatment apparatus 10 has a plurality of elements 22 shown in FIG. 2 connected in series, filled in a cylindrical vessel 24 shown in FIG. 5 to form a module 26, and the module 26 can be used alone or in parallel. It is configured by connecting.

  As shown in FIG. 2, the element 22 is configured by arranging a membrane unit 32 including an RO membrane 28 and a discharge pipe 30 around a water collection pipe 34. As shown in FIG. 3, the 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 configured by winding in a spiral around the water collection pipe 34. One end of the bag-like RO membrane 28 is opened, and the RO membrane 28 is bonded to the water collection pipe 34 so that the opening communicates with the through hole 36 of the water collection pipe 34 shown in FIG. The water to be treated flows on the outer surface of the RO membrane 28 and passes through the RO membrane 28 to be desalted. Then, the desalted water that has passed through the RO membrane 28 is collected from the inside of the RO membrane 28 into the water collection pipe 34 through the opening of the RO membrane 28 and the through holes 36 of the water collection pipe 34. The water is discharged from the element 22 from the water collecting pipe 34 through the discharge pipe 30. 3 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 when the RO membrane 28 is wound in a spiral shape. Reference numeral 40 denotes a mesh 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.

  FIG. 5 is a cross-sectional view of the reverse osmosis treatment apparatus 10 according to the embodiment. Both ends of the vessel 24 are opened so that water to be treated is introduced and discharged, and a predetermined operating pressure is applied to the opening on the introduction side by the high-pressure pump 14. FIG. 5 shows a module 26 in which five elements 22, 22... Are connected in series, but the number of elements 22 is not limited to five. Further, the vessel 24 can be constituted by FRP or the like so as to withstand high pressure (5 MPa or more).

  As shown in FIG. 5, the vessel 24 includes an introduction pipe 56 that introduces the liquid to be treated into the vessel 24, and a third discharge that discharges the concentrated water that has not been permeated to the water collection pipe 34. A tube 62 is provided. A concentrated water discharge valve 66 for adjusting the pressure in the vessel 24 is provided at the outlet of the third discharge pipe 62. In addition, a resistor 80 is provided in the water collecting pipe 34, a first discharge pipe 58 and a second discharge pipe 60 are provided on both sides of the vessel 24, and the permeated water that has passed through the RO membrane 28 is passed through the first discharge pipe. 58, the element 22 is discharged through the second discharge pipe 60. In addition, a measuring instrument 68 and a first valve 64 are provided at the outlet of the first discharge pipe 58, and a measuring instrument 70 is provided at the outlet of the second discharge pipe 60.

  According to the vessel 24, the water to be treated supplied from the tank 12 of FIG. 1 via the introduction pipe 56 is guided to the element 22 through the flow path 57, and the water to be treated passes through the RO membrane 28 of the element 22. After passing sequentially, water is collected in the water collection pipe 34. In the present embodiment, a resistor 80 is provided in the water collecting pipe 34, and the permeated water collected on the supply water side from the resistor 80 is supplied to the outside of the vessel 24 from the first discharge pipe 58. Discharged. Further, the permeated water collected on the concentrated water side is discharged from the second discharge pipe 60 to the outside of the vessel 24. The concentrated water that has not passed through the RO membrane 28 is discharged to the outside of the vessel 24 through the third discharge pipe 62.

  By providing the resistor 80 in the water collecting pipe 34 as in the present invention, the permeated water is divided into the supply water side and the concentrated water side, and discharged from the first discharge pipe 58 and the second discharge pipe 60. be able to.

  Non-uniformity in the amount of permeated water at the element position was (1) water temperature, (2) feed salt concentration, (3) water permeability and salt rejection of the RO membrane itself, (4) averaged over all membranes in the vessel. It is determined by the amount of permeated water around the membrane area, (5) recovery rate, and (6) pressure. Among these, (3), (4), and (5) are determined at the time of design. (1) and (2) change due to environmental changes, and (6) changes when the film is contaminated by operation. By adjusting the opening of the first valve 64, the concentrated water discharge valve 66, and the position of the resistor 80 according to the changes in (1), (2) and (6), the overall stability is reduced. The amount of permeated water can be secured. In particular, (1) since the water temperature varies depending on the season, it is necessary to appropriately adjust the water temperature.

  The position of the resistor 80 is not provided at the element unit, that is, at the connection portion of the elements, but each element in the vessel is regarded as one long element, and the position of the resistor 80 in the collecting pipe is arbitrarily determined. be able to. The position of the resistor 80 can be adjusted by pushing it out from either one of the elements 22 with something like a long bar.

  In addition, the amount of permeated water can be adjusted by determining the opening degree of the first valve 64 and the concentrated water discharge valve 66 by the measuring instruments 68 and 70 provided in the first discharge pipe 58 and the second discharge pipe 60. It can also be done. As the measuring instruments 68 and 70, a flow meter and a pressure gauge can be used.

  FIG. 6 is a diagram illustrating the relationship between the position of the RO membrane element and the relative flux of the permeated water in the reverse osmosis treatment device of the embodiment. In the data of the present invention, the non-permeable resistor 80 among the seven elements is installed at the end of the second element from the supply side, and the flow rate of the measuring instrument 68 is adjusted by the first valve 64. This is data obtained by conducting an experiment with the relative flux at the previous stage being 1.0 or less. As shown in FIG. 6, conventionally, a large amount of permeated water is generated from the supply water side, and the amount of permeate decreases as it goes to the concentrated water side. On the other hand, in the present invention, the resistor 80 is provided, and the first discharge pipe 58 is provided on the supply water side to discharge the permeate, so that the first discharge pipe 58 is connected. By adjusting the first valve 64, the pressure in the water collection pipe 34 on the supply water side is adjusted. The opening degree of the first valve 64 can be adjusted by a numerical value measured by the measuring device 68. Conventionally, the flow rate of the permeated water from the supply water side is large. However, in the present invention, the pressure on the supply water side can be adjusted, so the flow rate of the permeate water on the supply water side can be lowered than before. . As a result, the salt concentration on the concentrated water side can be reduced as compared with the conventional case, so that the non-uniformity of the permeated water amount of each RO membrane element can be eliminated. In this way, the permeated water is discharged from both sides of the first discharge pipe 58 and the second discharge pipe 60 of the vessel 24, and the water collection pipe is formed according to the opening degree of the first valve 64 and the concentrated water discharge valve 66. By adjusting the pressure in 34, the non-uniformity of the permeated water amount of each RO membrane can be eliminated. Therefore, power saving can be achieved and contamination of the RO membrane on the supply water side can be suppressed.

  In the present invention, a constant flow valve can be used as the first valve 64 instead of the adjustment valve capable of adjusting the opening degree. When the constant flow valve is used, the amount of permeated water in the water collecting pipe 34 is adjusted only by adjusting the position of the resistor 80.

  FIG. 7 shows data when the position of the non-permeable resistor 80 is installed at the end of the fourth element from the supply side. According to FIG. 7, the supply pressure to the vessel 24, that is, the pressure applied to the final stage of the element 22 can be adjusted to be the lowest. Power saving can be achieved by adjusting the supply pressure into the vessel 24 to be the lowest, and since the salt concentration is low in the previous stage, a predetermined flow rate of permeate can be maintained and stable. The permeated water can also be generated.

  Further, when the amount of permeated water of the RO membrane changes, the salt concentration rejection rate also changes. It is also possible to monitor the blocking rate and adjust the opening of the first valve 64, the concentrated water discharge valve 66, and the position of the resistor 80. The salt concentration rejection rate can be easily measured by measuring the electrical conductivity of the first discharge pipe 58 and the second discharge pipe 60.

  Next, the resistor 80 will be described. As the resistor 80, as shown in FIG. 9A, the entire resistor 80 is an elastic body 82, or as shown in FIG. 9B, the non-elastic body 84 is elastic in an O-ring shape. 82 is installed, and the elastic body 82 is closely attached to the inner wall of the water collecting pipe 34. As described above, since the position adjustment of the resistor 80 is adjusted by pushing out from the end of the water collecting pipe 34, the contact portion with the inner wall is preferably formed of an elastic body 82. However, it is preferable to have a resistance with the inner wall of the water collection pipe 34 so that the position does not change due to the flow of permeated water. As such an elastic body, for example, EPDM (ethylene propylene diene rubber), silicon or the like can be used.

  The resistor 80 can be made impermeable as shown in FIG. 10A and can be completely closed by the resistor 80 so that the permeate cannot move through the water collection pipe 34. Moreover, as shown in FIG.10 (b), it is also possible to make it water-permeable using a porous material. Further, as shown in FIGS. 10C and 10D, a slit may be provided between the resistor 80 and the inner wall of the water collecting pipe 34 to allow permeate to move. FIG. 8 shows data when the resistor of FIG. 10C is installed at the center of the second element from the supply side and at the center of the fifth element from the supply side. According to FIG. 8, it is possible to obtain a substantially uniform flux. By allowing the permeated water to move between the resistors 80, resistance can be provided on both sides of the water collecting pipe 34 sandwiching the resistor 80, so that the amount of permeated water can be made equal. Further, when the resistor 80 has water permeability, the number of the resistors 80 is not limited, and a plurality of resistors 80 may be installed. By installing a plurality, the pressure in the water collecting pipe 34 can be adjusted more finely, so that the non-uniformity of the permeated water amount of each RO membrane can be eliminated. Similarly, a resistor 80 that does not have water permeability can be used as the main resistor 80, and a resistor having water permeability can also be installed in order to adjust the amount of permeated water.

  DESCRIPTION OF SYMBOLS 10 ... Reverse osmosis processing apparatus, 12 ... Tank, 14 ... High pressure pump, 16 ... Permeate, 18 ... Concentrated water, 20 ... Desalination processing system, 22 ... Element, 24 ... Vessel, 26 ... Module, 28 ... RO membrane, DESCRIPTION OF SYMBOLS 30 ... Drain pipe, 32 ... Membrane unit, 34 ... Water collecting pipe, 36 ... Through-hole, 38, 40 ... Spacer, 56 ... Introducing pipe, 57 ... Flow path, 58 ... First discharge pipe, 60 ... Second Discharge pipe, 62 ... third discharge pipe, 64 ... first valve, 66 ... concentrated water discharge valve, 68, 70 ... measuring instrument, 80 ... resistor, 82 ... elastic body, 84 ... non-elastic body

Claim 1 of the present invention is a reverse osmosis treatment apparatus for achieving the above object , comprising a pressure vessel, an introduction pipe for supplying water to be treated to one end of the pressure vessel, and the pressure vessel. And a plurality of reverse osmosis membrane elements provided in the pressure vessel and provided with a reverse osmosis membrane, wherein the reverse osmosis membrane element further comprises A water collecting pipe through which the permeated water that has passed through the reverse osmosis membrane flows, the water collecting pipe connecting the plurality of reverse osmosis membrane elements in series in the pressure vessel, and the water collecting pipe, A resistor that separates the permeated water into a front stage that is a supply side of the water to be treated and a rear stage that is a discharge side of concentrated water, a first discharge pipe that discharges the permeated water of the front stage, and a rear stage A second discharge pipe for discharging the permeated water, wherein the first discharge pipe is a first discharge pipe. Reverse osmosis treatment apparatus, characterized in that it comprises a valve.

Claims (7)

A plurality of reverse osmosis membrane elements having a reverse osmosis membrane are connected in series by a water collecting pipe through which the permeated water that has passed through the osmosis membrane flows, in a pressure vessel having an introduction pipe for supplying the water to be treated. Has been
A resistor that separates the permeated water into a front stage on the supply side of the treated water and a rear stage on the concentrated water discharge side in the water collecting pipe;
A first discharge pipe for discharging the permeated water at the front stage, a second discharge pipe for discharging the permeated water at the rear stage, and a third discharge pipe for discharging concentrated water,
A reverse osmosis treatment apparatus comprising a first valve in the first discharge pipe.   The reverse osmosis treatment device according to claim 1, wherein the resistor can be installed at an arbitrary position in the water collecting pipe.   The reverse osmosis treatment apparatus according to claim 1, wherein the resistor is impermeable to water.   The reverse osmosis treatment apparatus according to claim 1, wherein the resistor is water permeable.   The reverse osmosis treatment apparatus according to claim 4, wherein the resistor is made of a porous material.   The reverse osmosis treatment apparatus according to claim 1, wherein a slit through which permeated water passes is formed in the resistor.   The reverse osmosis treatment apparatus according to claim 4, wherein a plurality of the resistors are provided in the water collecting pipe.

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