JP2010058013A - Pure water production system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pure water production system which reduces a scale risk in an electric deionization module without using a chemical agent. <P>SOLUTION: The pure water production system for producing pure water by treating raw water with a water softener 1, a reverse osmosis membrane device 2, and an electric deionizer 10 in this order includes: a detector 22 for the hardness of a permeate installed between the reverse osmosis membrane device 2 and the electric deionizer 10 to detect the hardness of the permeate; a control means 15 for concentrated water flow rate to control the flow rate of the permeate supplied to a concentration chamber 6b when supplying the permeate from the reverse osmosis membrane device 2 to a desalting chamber 6a and the concentration chamber 6b of the electric deionizer 10; and a control portion 21 for controlling the concentrated water flow rate control means 15 based on the detection signals of the detector 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pure water production system in which raw water is treated using an electrodeionization apparatus.

  As a system for producing pure water by treating recovered water from industrial water, city water, well water, or semiconductor manufacturing process, etc. A water production system is known (for example, Patent Documents 1 and 2).

  In the electrodeionization device, a cation exchange membrane and an anion exchange membrane are alternately arranged between a pair of electrodes to form a demineralization chamber, a concentration chamber, and an electrode chamber, and the demineralization chamber is filled with an ion exchanger. The deionized chamber, the concentrating chamber, and the electrode chamber are supplied with treated water, and the treated water from which ions have been removed in the desalting chamber is supplied from the treated water outflow line to use points, etc. In the concentration chamber, the ions that have moved from the desalting chamber are concentrated and discharged to the outside as concentrated water, and are composed of an electrode chamber.

Conventionally, in an electrodeionization apparatus, there is a technique in which softened water treated with a softener is used as concentrated water for an electrodeionization apparatus, and a scale inhibitor is added to the softened water.
JP 2003-1259 A JP 2001-29752 A JP-T-2007-528781

  In such an electrodeionization apparatus, on the concentration chamber side where ions move from the demineralization chamber, a scale such as calcium carbonate is formed on the surface of the ion exchange membrane, and so-called scale risk occurs. It's easy to do. In patent document 3, in the electrodeionization apparatus, while using the softened water processed with the softener as concentrated water of an electrodeionization apparatus, the scale inhibitor is added to this softened water. However, draining concentrated water containing a chemical such as a scale inhibitor out of the system may cause environmental pollution.

  This invention is made | formed in view of such a subject, and it aims at providing the pure water manufacturing system which reduced the scale risk of the electrodeionization module, without using a chemical | medical agent.

  The present inventors detect the hardness of the permeated water or pretreated soft water supplied to the electrodeionization apparatus, and increase the feed water flow rate to the concentration chamber of the electrodeionization module based on the hardness detection signal, thereby The inventors have found that the concentration risk can be avoided and the scale risk can be reduced, and based on this, the following new pure water production system has been invented.

(1) In a pure water production system for producing pure water by processing raw water in the order of a water softening device, a reverse osmosis membrane device, and an electrodeionization device, provided between the reverse osmosis membrane device and the electrodeionization device When the permeated water hardness detector detects the hardness of the permeated water and the permeated water is supplied from the reverse osmosis membrane device to the demineralization chamber and the concentration chamber of the electrodeionization device, the permeated water hardness detector is supplied to the concentration chamber. Concentrated water flow rate adjusting means for adjusting the flow rate of the permeated water, and a control unit for controlling the concentrated water flow rate adjusting means based on a detection signal of the permeated water hardness detector. Manufacturing system.

(2) In a pure water production system for producing pure water by treating raw water in the order of a water softening device, a reverse osmosis membrane device, and an electrodeionization device, it is provided between the water softening device and the reverse osmosis membrane device. In addition, when the permeated water is supplied from the reverse osmosis membrane device to the demineralization chamber and the concentration chamber of the electrodeionization device, the permeated water supplied to the concentration chamber is detected. A pure water production system comprising: a concentrated water flow rate adjusting unit that adjusts the flow rate of the water; and a control unit that controls the concentrated water flow rate adjusting unit based on a detection signal of the soft water hardness detector.

(3) a flow rate sensor that is provided in a treated water outflow line through which treated water deionized in the deionization chamber of the electrodeionization apparatus flows out and detects the flow rate of treated water flowing in the treated water outflow line; The pure water according to (1) or (2), further comprising: a control unit that controls a speed of a water supply pump that supplies permeated water to the electrodeionization device based on a flow rate detection signal of a flow rate sensor. Manufacturing system.

(4) The concentrated water flow rate adjusting means is connected in parallel to the open / close switching valve and the first constant flow valve connected in series to the inflow line to the concentrating chamber, and the open / close switching valve and the first constant flow valve. The control valve controls the on-off switching valve based on a detection signal of the permeated water hardness detector or the soft water hardness detector. (3) The pure water production system according to any one of (3).

  According to the pure water production system of the present invention, the hardness of the permeated water supplied to the electrodeionization device or the soft water of the pretreatment is detected, and the flow rate of the feedwater to the concentration chamber of the electrodeionization module is determined based on the hardness detection signal. By increasing, local concentration can be avoided. As a result, the scale risk of the electrodeionization module can be reduced without using a drug.

  FIG. 1 is a system configuration diagram of a pure water production system according to a first embodiment of the present invention.

  In FIG. 1, a pure water production system includes a soft water device 1 for softening raw water, a reverse osmosis membrane device 2 for primary deionization of softened water, and permeated water treated by the reverse osmosis membrane device 2. A water supply tank 3 for storage is provided. A permeated water line 4 is provided downstream of the water supply tank 3, and the permeated water is sent to the electrodeionization module 6 of the electrodeionization apparatus 10 as treated water by a feedwater pump 5 provided in the permeate water line 4. Subsequent deionization is performed.

  In the electrodeionization module 6, a cation exchange membrane and an anion exchange membrane are alternately arranged between a pair of electrodes (not shown) so that a demineralization chamber 6 a, a concentration chamber 6 b, and an electrode chamber 6 c are partitioned and removed. The salt chamber 6a is filled with an ion exchanger. The desalting chamber 6a is connected to a desalting chamber inflow line 7 through which treated water flows and a treated water outflow line 8 from which treated water from which ions have been removed in the desalting chamber 6a flows out. The concentration chamber 6b is connected with a concentration chamber inflow line 11 through which water to be treated is introduced, and a concentration water drain line 12 for discharging the concentrated water in which ions are concentrated in the concentration chamber 6b. The electrode chamber 6c is connected to an electrode chamber inflow line 13 and an electrode water outflow line 14 through which treated water flows. A flow rate adjusting valve 9 is connected to each of the desalting chamber inflow line 7, the concentration chamber inflow line 11, and the electrode chamber inflow line 13.

  Concentration chamber flow rate adjusting means 15 is provided in the concentration chamber inflow line 11. The concentrating chamber flow rate adjusting means 15 is in parallel with a valve train composed of the on-off switching valve 16 and the first constant flow valve 17 connected in series to the concentrating chamber inflow line 11 and the on-off switching valve 16 and the first constant flow valve 17. A second constant flow valve 18 connected thereto is provided. The treated water outflow line 8 is provided with a flow rate sensor 20 that detects the flow rate of the treated water flowing through the treated water outflow line 4, and a flow rate detection signal of the flow rate sensor 20 is sent to the control unit 21, and the control unit 21 supplies a water supply pump The number of rotations of 5, that is, the rotation speed is controlled.

  The permeated water line 4 is provided with a permeated water hardness detector 22 that detects the hardness of the permeated water. The detection signal of the permeated water hardness detector 22 is sent to the control unit 21, and the control unit 21 controls the concentrating chamber flow rate adjusting means 15 based on this detection signal.

  The permeated water hardness detector 22 adds, for example, a reagent whose main component is a metal indicator that changes color by reacting with hardness components (calcium ions and magnesium ions) to sample water sampled from the permeated water line 4. The hardness of the sample water is determined by optically detecting the hue change due to the reaction. As the permeated water hardness detector 22, for example, those having the configurations disclosed in Japanese Patent No. 3186777 and Japanese Patent No. 3214400 are suitably used. As the reagent, for example, Eriochrome Black T (metal indicator), EDTA-Mg (sensitizer), and a one-component reagent composed of triethanolamine and ethylene glycol (non-aqueous solvent) are preferably used. The measurement process in the transmitted water hardness detector 22 usually includes adding a reagent to a measurement cell containing a predetermined amount of sample water and mixing it, and applying light of two or more specific wavelengths to the sample water after the color reaction. Irradiating to detect transmittance (or absorbance). And the hardness of sample water is determined based on the determination table which shows the relationship between the detected value of transmittance, and hardness, and the value is output to the control part 21 as a detection signal.

  Next, the operation will be described. Raw water such as industrial water, city water, and well water is softened by the water softening device 1, then supplied to the reverse osmosis membrane device 2 and subjected to primary deionization treatment, and the permeate is treated water from the permeate line 4. The water is supplied to the electrodeionization module 6 through the water supply pump 5. The treated water flowing in from the desalting chamber inflow line 7 is discharged from the treated water outflow line 8 after ions are removed in the desalting chamber 6a. The treated water that has flowed in from the concentrating chamber inflow line 11 is concentrated in the concentrating chamber 6 b, and then the concentrated water is discharged from the concentrated water drain line 12. In addition, the water to be treated that flows in from the electrode chamber inflow line 11 is discharged from the electrode water outflow line 14 as electrode water.

  The hardness of the permeated water flowing through the permeated water line 4 is detected by the permeated water hardness detector 22, and the detection signal is sent to the control unit 21. The control unit 21 controls the open / close switching valve 16 of the concentrating chamber flow rate adjusting means 15 based on this detection signal. That is, when the permeate hardness detector 22 detects a leak of hardness into the permeate, the on-off switching valve 16 is opened to increase the flow rate of the water to be treated flowing from the concentration chamber inflow line 11 and to reduce the drainage flow rate. Increase the water recovery rate (= treated water flow rate / [treated water flow rate + drainage flow rate]). By this operation, local concentration is avoided, and scale formation in the concentration chamber can be prevented.

  The flow rate of the treated water flowing in the treated water outflow line 8 is detected by the flow rate sensor 20, and this flow rate detection signal is sent to the control unit 21, and the control unit 21 controls the rotation speed of the feed water pump 5, that is, the rotation speed. Yes. That is, the flow rate of the treated water supplied to the desalting chamber 6a is controlled so that the flow rate of the treated water flowing out from the treated water outflow line 8 is always kept constant.

  FIG. 2 is a system configuration diagram of a pure water production system according to the second embodiment of the present invention. In the second embodiment, a soft water hardness detector 24 is provided in the soft water line 23 extending from the soft water device 1 to the reverse osmosis membrane device 2. Here, the soft water hardness detector 24 is the same as the permeated water hardness detector 22 described in the first embodiment. The hardness of the soft water flowing through the soft water line 23 is detected by the soft water hardness detector 24, and the detection signal is sent to the control unit 21. The control unit 21 controls the open / close switching valve 16 of the concentrating chamber flow rate adjusting means 15 based on this detection signal. That is, when the soft water hardness detector 24 detects a hardness leak into the soft water, the flow rate of the permeated water flowing from the concentrating chamber inflow line 11 is increased by opening the on-off switching valve 16 to increase the drainage flow rate. Reduce the water recovery rate (= treated water flow rate / [treated water flow rate + drainage flow rate]). By this operation, local concentration is avoided, and scale formation in the concentration chamber can be prevented. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As described above, according to the embodiment of the present invention, the permeated water hardness detector 22 for detecting the hardness of the permeated water is provided between the reverse osmosis membrane device 2 and the electrodeionization device 10, and the reverse osmosis membrane device. When the permeated water is supplied from 2 to the demineralization chamber 6a and the concentration chamber 6b of the electrodeionization apparatus 10, a concentrated water flow rate adjusting means 15 is provided for adjusting the flow rate of the permeated water supplied to the concentration chamber 6b. Since the concentrated water flow rate adjusting means 15 is controlled based on the detection signal of the hardness detector 22, the flow rate supplied to the concentration chamber 6b is determined by the hardness of the permeated water, which is a major factor in the scale formation of the electrodeionization module 6. By increasing and avoiding local concentration, the scale risk can be reduced.

  Moreover, according to this embodiment, the soft water hardness detector 24 for detecting the hardness of the soft water is provided between the water softening device 1 and the reverse osmosis membrane device 2, and the desalination of the electrodeionization device 10 from the reverse osmosis membrane device 2 is performed. When supplying the permeated water to the chamber 6a and the concentrating chamber 6b, a concentrated water flow rate adjusting means 15 for adjusting the flow rate of the permeated water supplied to the concentrating chamber 6b is provided, and concentrated based on the detection signal of the soft water hardness detector 24. Since the water flow rate adjusting means 15 is controlled, the flow rate supplied to the concentrating chamber 6b is increased by the hardness of soft water, which is a major factor for the scale formation of the electrodeionization module 6, and scale concentration is avoided by avoiding local concentration. Can be reduced.

  Further, according to the present embodiment, the rotation of the feed water pump 5 that detects the flow rate of the treated water flowing in the treated water outflow line 8 and feeds the permeated water to the electrodeionization device 10 based on the flow rate detection signal of the flow rate sensor 20. Since the number, that is, the rotation speed is controlled, the flow rate of the treated water from the electrodeionization apparatus 10 can be kept constant even if the drainage flow rate from the concentration chamber 6b increases and the water recovery rate fluctuates.

  Further, according to the present embodiment, the on-off switching valve 16 and the first constant flow valve 17 connected in series to the concentrating chamber inflow line 11 and the second constant flow valve 18 connected in parallel to these valve trains. Since the concentrating chamber flow rate adjusting means 15 is configured, the flow rate can be adjusted in two stages by controlling the open / close switching valve 16, and the second constant flow valve 18 is always constant even when the open / close switching valve 16 is closed. A flow rate of permeate can flow.

  As mentioned above, although embodiment of this invention was described, it only illustrated the specific example and does not specifically limit this invention, the electrodeionization apparatus 10, the electrodeionization module 6, the water softening apparatus 1, and a reverse osmosis membrane The specific configuration and arrangement of the device 2, the permeated water hardness detector 22, the soft water hardness detector 24, and the like can be appropriately changed in design. 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 block diagram of the pure water manufacturing apparatus of 1st Embodiment of this invention. It is a system block diagram of the pure water manufacturing apparatus of 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Soft water apparatus 2 Reverse osmosis membrane apparatus 5 Water supply pump 6 Electrodeionization module 8 Treated water outflow line 10 Electrodeionization apparatus 15 Concentration chamber flow rate adjustment means 16 On-off switching valve 17 First constant flow valve 18 Second constant flow valve 20 Flow rate Sensor 22 Permeated water hardness detector 23 Soft water line 24 Soft water hardness detector

Claims (4)

In a pure water production system for producing pure water by processing raw water in the order of a water softening device, a reverse osmosis membrane device and an electrodeionization device,
A permeated water hardness detector provided between the reverse osmosis membrane device and the electrodeionization device for detecting the hardness of the permeated water;
Concentrated water flow rate adjusting means for adjusting the flow rate of the permeated water supplied to the concentration chamber when supplying the permeated water from the reverse osmosis membrane device to the demineralization chamber and the concentration chamber of the electrodeionization device;
And a controller for controlling the concentrated water flow rate adjusting means based on a detection signal of the permeated water hardness detector. In a pure water production system for producing pure water by processing raw water in the order of a water softening device, a reverse osmosis membrane device and an electrodeionization device,
A soft water hardness detector provided between the water softening device and the reverse osmosis membrane device to detect the hardness of soft water;
Concentrated water flow rate adjusting means for adjusting the flow rate of the permeated water supplied to the concentration chamber when supplying the permeated water from the reverse osmosis membrane device to the demineralization chamber and the concentration chamber of the electrodeionization device;
And a control unit that controls the concentrated water flow rate adjusting means based on a detection signal of the soft water hardness detector. A flow rate sensor that is provided in a treated water outflow line through which treated water deionized in the demineralization chamber of the electrodeionization apparatus flows, and detects a flow rate of treated water flowing in the treated water outflow line;
The pure water production according to claim 1, further comprising: a control unit that controls a speed of a water supply pump that supplies permeated water to the electrodeionization device based on a flow rate detection signal of the flow rate sensor. system. The concentrated water flow rate adjusting means includes:
An on-off switching valve and a first constant flow valve connected in series to the inflow line to the concentrating chamber;
A second constant flow valve connected in parallel with the open / close switching valve and the first constant flow valve;
The pure water production system according to any one of claims 1 to 3, wherein the control unit controls the open / close switching valve based on a detection signal of the permeated water hardness detector or the soft water hardness detector. .

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