JP2009279472A - Reverse osmosis membrane device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain stable water quality regardless of the influence of a change in water quality of raw water and aged deterioration of a membrane of a reverse osmosis membrane module. <P>SOLUTION: A reverse osmosis membrane device comprises: a reverse osmosis membrane module 11 which is supplied with raw water through a raw water line and which discharges it as permeate clear of impurities in the raw water and as concentrate with the impurities concentrated; a permeate return line 6 which returns the permeate to the raw water line 12 from a permeate line 14 into which the permeate of the reverse osmosis membrane module 11 is discharged; a flow regulating valve 8 installed in the permeate return line 6; a raw water quality detector 2 installed in the raw water line 12 to detect the water quality of the raw water; and a valve control means 9 which controls the flow regulating valve 8 based on detection signals of the raw water quality detector 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reverse osmosis membrane device, and more particularly to a reverse osmosis membrane device that obtains a stable permeated water quality by returning a part of permeated water to the raw water side based on information on the raw water to be treated.

  The reverse osmosis membrane device selectively permeates and collects only water as a solvent by applying a pressure higher than the osmotic pressure of the water to be treated, utilizing the property of the reverse osmosis membrane that allows the solvent to pass but does not allow the solute to permeate. Device. In the fresh water generator using this reverse osmosis membrane, the permeated water quality (manufactured water quality) is continuously detected, and the raw water (treated water) supplied to the reverse osmosis membrane so that this water quality becomes a predetermined value. Is known that is diluted with permeated water (see, for example, Patent Document 1).

JP-A 63-197596

  The quality of the permeated water produced by the reverse osmosis membrane is greatly influenced not only by the performance of the reverse osmosis membrane itself, but also by the quality of the raw water, so the ratio to be diluted varies depending on the state of the raw water. Therefore, as in Patent Document 1, the permeated water quality is continuously detected, and simply diluting the raw water with the permeated water based on this water quality, the information on the raw water is not taken in. There was a problem that it was difficult to stably obtain a predetermined permeated water quality.

  Therefore, there is a need for a reverse osmosis membrane apparatus that can obtain a stable permeated water quality regardless of fluctuations in the quality of raw water or the effects of aging of the membrane of a reverse osmosis membrane module. The above is the subject of the present invention.

  The present invention has been made in view of such a problem, and it is possible to obtain a stable permeated water quality irrespective of the influence of the water quality fluctuation of the raw water and the aging deterioration of the membrane of the reverse osmosis membrane module. An object is to provide an osmotic membrane device.

  The present inventor has found that a predetermined permeated water quality can be obtained regardless of fluctuations in the quality of the raw water by returning a part of the permeated water to the raw water side based on the water quality information of the raw water. The inventors have invented the following new reverse osmosis membrane device.

  (1) A reverse osmosis membrane module that supplies raw water through a raw water line and discharges the permeated water from which impurities in the raw water have been removed, and a concentrated water in which impurities are concentrated, and the permeated water from the reverse osmosis membrane module is discharged. The permeated water return line for returning permeated water from the permeated water line to the raw water line, the flow rate adjusting valve provided in the permeated water return line, and the raw water quality for detecting the quality of the raw water provided in the raw water line A reverse osmosis membrane device comprising: a detector; and valve control means for controlling the flow rate adjusting valve based on a detection signal of the raw water quality detector.

  (2) A permeated water quality detector for detecting the quality of permeated water is provided in the permeated water line, and the flow control valve is controlled by the valve control means based on a detection signal of the permeated water quality detector. (2) The reverse osmosis membrane device according to (1).

  (3) A concentrated water quality detector for detecting the quality of the concentrated water is provided in the concentrated water line for discharging the concentrated water, and the flow rate is controlled by the valve control unit based on a detection signal of the concentrated water quality detector. The reverse osmosis membrane device according to (1) or (2), wherein the regulating valve is controlled.

  (4) A water temperature detector is connected upstream or downstream of each of the raw water quality detector, the permeated water quality detector, and the concentrated water quality detector, and the valve control means is based on a detection signal of the water temperature detector. The reverse osmosis membrane device according to any one of (1) to (3), wherein the flow rate adjusting valve is controlled.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to obtain the stable permeated water quality irrespective of the influence of the water quality fluctuation | variation of raw | natural water, or the aged deterioration of the membrane of a reverse osmosis membrane module.

  Hereinafter, embodiments of the present invention will be described. The reverse osmosis membrane device according to the first embodiment includes a reverse osmosis membrane module that is supplied with raw water via a raw water line and discharges the permeated water from which impurities in the raw water are removed and the concentrated water in which impurities are concentrated. Yes. A permeate return line for returning permeate from the permeate line from which the permeate of the reverse osmosis membrane module is discharged to the raw water line is provided. This permeate return line is provided with a flow control valve, and the raw water line is provided with a raw water quality detector for detecting the quality of the raw water and a water temperature detector for detecting the water temperature. By controlling the flow rate adjusting valve based on the detection signal, a predetermined amount of permeated water is mixed into the raw water to obtain a predetermined permeated water quality.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a system configuration diagram of a reverse osmosis membrane device according to a first embodiment of the present invention.

  The reverse osmosis membrane device uses reverse osmosis membranes (including nanofiltration membranes) that allow solvents to pass through but not solutes, and from the osmotic pressure of treated water containing impurities such as dissolved salts and silica. A high pressure is applied to selectively permeate and collect only water as a solvent.

  As shown in FIG. 1, a reverse osmosis membrane device 10 is provided on the upstream side of a cylindrical reverse osmosis membrane module 11 having a large number of reverse osmosis membranes (including nanofiltration membranes) and the reverse osmosis membrane module 11. Further, a raw water line 12 to which raw water from the raw water tank 1 is supplied, a pump 13 for pressurizing the raw water provided in the raw water line 12, and an impurity provided on the downstream side of the reverse osmosis membrane module 11. The permeated water line 14 for discharging the permeated water from which the water has been removed, and the concentrated water line 15 for draining the concentrated water enriched with impurities, provided on the downstream side of the reverse osmosis membrane module 11.

  Between the raw water tank 1 and the pump 13, a water quality detector 2 for detecting the quality (for example, electrical conductivity) of the raw water and a water temperature detector 3 for detecting the water temperature are provided. The permeate line 14 is provided with a flow meter 4 and a flow rate adjustment valve 5. From the downstream of the reverse osmosis membrane module 11 in the permeate water line 14 (between the reverse osmosis membrane module 11 and the flow meter 4) and upstream of the reverse osmosis membrane module 11 in the raw water line 12 (between the water temperature detector 3 and the pump 13. Permeated water return line 6 is provided. The permeate return line 6 is provided with a flow meter 7 and a flow rate adjustment valve 8.

  The control unit 9 receives signals from the water quality detector 2, the water temperature detector 3, the flow meter 4 and the flow meter 7 through the signal lines 2a, 3a, 4a and 7a, respectively, and the signal lines 5b, 8b and 13b. The flow rate adjustment valve 5 of the permeate line 14, the flow rate adjustment valve 8 of the permeate return line 6, and the pump 13 are controlled via the inverter 16.

  The raw water tank 1 stores raw water such as tap water and industrial water, and the raw water from the raw water tank 1 is supplied from the raw water line 12 to the reverse osmosis membrane module 11 by the pump 13. Is processed. Meanwhile, the quality of raw water (for example, electrical conductivity) is detected by the water quality detector 2, and the temperature of the raw water is detected by the water temperature detector 3. The raw water quality information and the water temperature information are transmitted through the signal lines 2 a and 3 a. Is transmitted to the control unit 9 via The permeated water treated in the reverse osmosis membrane module 11 is discharged from the permeated water line 14 to the water supply tank 17, and the water in the water supply tank 17 is supplied to, for example, a boiler system, a pure water device, and the like. The concentrated water in which the impurities are concentrated is discharged from the concentrated water line 15.

  A part of the permeate passing through the permeate line 14 is returned to the raw water line 12 via the permeate return line 6. The control unit 9 controls the flow rate adjustment valve 8 based on the raw water quality information and the raw water temperature information detected by the water quality detector 2 and the water temperature detector 3 to optimize the return amount of the permeated water passing through the permeate return line 6. Adjust to the amount. Specifically, the return amount of the permeated water is increased as the quality of the raw water is worse (the higher the electrical conductivity) or the higher the temperature of the raw water. That is, the greater the amount of permeated water returned, the greater the water quality improvement effect and the smaller the amount of drainage to the water supply tank 17. Therefore, a predetermined water quality can be ensured by controlling the flow rate adjusting valve 8. Signals from the flow meters 4 and 7 are also input to the control unit 9, and the control unit 9 uses these pieces of flow rate information for controlling the flow rate adjusting valve 8.

  Depending on the equipment supplied with water from the reverse osmosis membrane device 10, it may be required to ensure a predetermined water quality without reducing the amount of drainage to the water supply tank 17. In that case, the rotation speed of the pump 13 is controlled by the inverter 16 so that the flow rate detected by the flow meter 4 becomes the target water amount, and the amount of drainage to the water supply tank 17 is maintained at a constant amount. That is, as the return amount of permeated water increases, the rotation speed of the pump 13 is increased and the amount of water supplied to the reverse osmosis membrane module 11 is increased so that a certain amount of permeated water is sent to the water supply tank 17.

  Moreover, when there is a raw water pressure in the raw water line 12 on the upstream side of the pump 13, the permeated water must be returned against this raw water pressure. For this reason, the flow control valve 5 as a throttle valve is provided in the permeate line 14 to add back pressure, or the permeate return line 6 is provided with a circulation pump (not shown) to pressurize the return. The pressure of the permeated water is made higher than the raw water pressure.

  In the reverse osmosis membrane device 10 of the first embodiment, a permeate return line 6 from the permeate line 14 to the raw water line 12 is provided, and the permeate return line 6 based on the detection information of the water quality detector 2 and the water temperature detector 3. By controlling the flow rate regulating valve 8, it is possible to always obtain a stable permeated water quality even if the raw water quality changes or the water temperature changes. In addition, when the water temperature information by the water temperature detector 3 is used in combination, the accuracy of water quality adjustment is further improved, but it is also possible to adopt a configuration in which only the water quality information by the water quality detector 2 is used.

  FIG. 2 is a system configuration diagram of a reverse osmosis membrane device according to a second embodiment of the present invention. In addition, the same member and the same function as 1st Embodiment attach | subject the same code | symbol, and abbreviate | omit description.

  As shown in FIG. 2, in addition to the first embodiment, the reverse osmosis membrane device of the second embodiment includes a water quality detector 18 and a water temperature detector 19 in the permeated water line 14, and a water quality detector in the concentrated water line 15. 20 and a water temperature detector 21 are provided, and the permeated water information and the concentrated water information are input from the water quality detectors 18 and 20 and the water temperature detectors 19 and 21 to the control unit 9 through the signal lines 18b, 19b, 20b, and 21b. The flow rate adjusting valve 8 is controlled by the control unit 9.

  In the reverse osmosis membrane device of the second embodiment, the quality and water temperature information of the permeated water and concentrated water are input to the control unit 9 together with the quality and temperature information of the raw water, and are used to control the flow rate adjustment valve 8. For this reason, for example, when the processing capacity of the reverse osmosis membrane module 11 is reduced due to aging deterioration of the membrane or the like, the water quality information of the permeated water and the concentrated water fluctuates. By controlling, it becomes possible to ensure a predetermined permeated water quality.

  As described above, according to the embodiment of the present invention, a permeate return line for returning permeate from the permeate line from which the permeate of the reverse osmosis membrane module is discharged to the raw water line is provided, and the quality of the raw water is improved. By controlling the flow rate adjustment valve of the permeated water return line based on the detection signal of the raw water quality detector to be detected, a stable permeated water quality can always be obtained even if the raw water quality varies.

  In addition, according to the present embodiment, the reverse osmosis membrane due to aging deterioration of the membrane, etc., by controlling the flow rate adjustment valve of the permeate return line based on the detection signal of the permeate water quality detector provided in the permeate line. Even when the processing capacity of the module is reduced, it is possible to control the flow rate adjustment valve based on the water quality information of the permeated water to ensure a predetermined permeated water quality.

  In addition, according to the present embodiment, the reverse osmosis membrane due to aging deterioration of the membrane, etc. by controlling the flow rate adjustment valve of the permeate return line based on the detection signal of the concentrated water quality detector provided in the concentrated water line Even when the processing capacity of the module is reduced, it is possible to control the flow rate adjustment valve based on the water quality information of the concentrated water to ensure a predetermined permeated water quality.

  In addition, according to this embodiment, a water temperature detector is provided together with a water quality detector, and by controlling the flow rate adjustment valve based on the detection signal of the water temperature detector, information on the water temperature that affects the membrane performance is also taken into account. Thus, the return amount of the permeate return line can be adjusted, and water quality adjustment with higher accuracy can be performed.

  As mentioned above, although embodiment of this invention was described, only the specific example was illustrated, it does not specifically limit this invention, the reverse osmosis membrane module 11, the permeate return line 6, the water quality detectors 2, 18, 20, the specific configurations and arrangements of the water temperature detectors 3, 19, 21 and the flow rate adjusting valve 8 can be appropriately changed. In addition, the effects described in the above-described embodiment only list the most preferable effects resulting from the present invention, and the effects according to the present invention are not limited to those described in the embodiments of the present invention. Absent.

It is a system configuration figure of the reverse osmosis membrane device of a 1st embodiment of the present invention. It is a system block diagram of the reverse osmosis membrane apparatus of 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw water tank 2 Water quality detector 3 Water temperature detector 6 Permeated water return line 8 Flow control valve 9 Control part 10 Reverse osmosis membrane device 11 Reverse osmosis membrane module 12 Raw water line 14 Permeated water line 15 Concentrated water line 18 Water quality detector 19 Water temperature Detector 20 Water quality detector 21 Water temperature detector

Claims (4)

A reverse osmosis membrane module that supplies raw water through the raw water line and discharges it as permeated water from which impurities in the raw water have been removed and concentrated water in which impurities are concentrated;
A permeate return line for returning permeate from the permeate line from which the permeate of the reverse osmosis membrane module is discharged to the raw water line;
A flow control valve provided in the permeate return line;
A raw water quality detector provided in the raw water line for detecting the quality of the raw water;
A reverse osmosis membrane device comprising: valve control means for controlling the flow rate adjusting valve based on a detection signal of the raw water quality detector.   A permeated water quality detector for detecting the quality of permeated water is provided in the permeated water line, and the flow rate control valve is controlled by the valve control means based on a detection signal of the permeated water quality detector. The reverse osmosis membrane device according to claim 1.   A concentrated water quality detector for detecting the quality of the concentrated water is provided in the concentrated water line for discharging the concentrated water, and the flow rate adjusting valve is controlled by the valve control means based on a detection signal of the concentrated water quality detector. The reverse osmosis membrane device according to claim 1 or 2, which is controlled.   A water temperature detector is connected upstream or downstream of each of the raw water quality detector, permeate water quality detector and concentrated water quality detector, and the valve control means adjusts the flow rate based on a detection signal of the water temperature detector. The reverse osmosis membrane device according to any one of claims 1 to 3, wherein the valve is controlled.

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