JP4978591B2 - Pure water production equipment - Google Patents

Description

  The present invention relates to a pure water production apparatus that treats raw water 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 apparatus is known (for example, Patent Documents 1 and 2).
JP 2003-1259 A JP 2001-29752 A

In the electrodeionization apparatus, a cation exchange membrane and an anion exchange membrane are alternately arranged between a pair of electrodes to form a demineralization chamber and a concentration chamber, and the demineralization chamber is filled with an ion exchanger. Deionized water is obtained by applying a direct current voltage and / or direct current to the electrodeionization module and passing the treated water treated by a reverse osmosis membrane device or the like. In the deionization chamber of this electrodeionization module, a concentration gradient is produced in which the ion concentration on the inlet side is high during normal operation and the ion concentration decreases toward the outlet side. For this reason, the specific resistance of deionized water increases on the outlet side, but when the operation is stopped (application of DC voltage is stopped), the concentration gradient disappears due to ion diffusion, and the specific resistance of deionized water decreases. If the water is passed while the specific resistance of the deionized water is lowered when the operation is resumed, the purity of the obtained deionized water is lowered, so that it is not suitable for use as it is. Therefore, conventionally, a return line branched from a deionized water line from which deionized water treated by the electrodeionization apparatus is discharged is provided, and when the operation is resumed, the treated water before the electrodeionization apparatus is connected from this return line. A circulation operation method in which water is circulated through the tank is adopted .

  Furthermore, conventionally, when the water storage level of the treated water tank in the previous stage of the electrodeionization apparatus is lowered below a predetermined level, the electrodeionization apparatus is stopped to protect the water supply pump and the ion exchange membrane. Therefore, there is a problem that it takes time to restart at the next restart of operation.

This invention is made | formed in view of such a subject, and provides the pure water manufacturing apparatus which can shorten the next starting time by switching to circulation operation by the fall of the water storage level of a treated water tank. For the purpose.

The present inventor detects the water storage level of the treated water tank in the previous stage of the electrodeionization device, and when it falls to a predetermined level or less, by switching to the circulation operation, the electrodeionization device is not stopped next time. It has been found that the startup time can be shortened, and based on this, the inventors have invented a new pure water production apparatus as described below.

( 1 ) A reverse osmosis membrane device for treating water to be treated, a treated water tank for storing treated water treated by the reverse osmosis membrane device, and an electrodeionization device for treating treated water supplied from the treated water tank A deionized water line that discharges deionized water treated by the electrodeionization device, a return line that branches from the deionized water line and returns the deionized water to the treated water tank, and the deionized water A switching valve which is provided at a branch portion between the water line and the return line and switches between a circulating operation for flowing deionized water to the return line and a non-circulating operation for flowing the deionized water line; And / or a power supply device for applying a direct current, a level sensor for water storage level detection provided in the treated water tank, and when the water storage level falls below a predetermined level, Based on the detection signal of the serial level sensor, wherein a control unit for switching the circulation operation of the switching valve, water purifying apparatus, comprising the.

( 2 ) A flow rate adjustment valve that adjusts the flow rate to the electrodeionization device and a voltage control unit that adjusts the voltage of the power supply device, wherein the control unit switches the switching valve to circulation operation, The pure water production apparatus according to ( 1 ), wherein the flow rate adjusting valve is throttled and control is performed to reduce the voltage applied to the power supply device.

According to the water purifying system engaged Ru in the present invention, without water level of treated water tank may stop device be reduced by switching the circulation operation, it is possible to shorten the next boot time.

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

  In FIG. 1, 1 is a reverse osmosis membrane device, 2 is a treated water tank, 3 is an electrodeionization device, 4 is a DC power supply device, 5 is a control unit, 6 is a start switch, and 7 is a switching valve.

  The raw water is filtered by an activated carbon filter (not shown) or the like and then desalted by the reverse osmosis membrane device 1, and the obtained treated water is stored in the treated water tank 2. The treated water in the treated water tank 2 is sent to the electrodeionization device 3 and further purified, and then sent from the deionized water line 8 to the use point as deionized water (pure water). Further, in the pure water production apparatus according to this embodiment, a return line 9 is provided that branches from the deionized water line 8 via the switching valve 7 and returns the treated water to the treated water tank 2.

  The start switch 6 is turned on / off according to the use state of deionized water at the use point. For example, a flow switch provided in the deionized water line 8 or a deionized water storage tank (not shown). ) Is used. That is, the activation switch 6 is turned on when deionized water is used at the point of use, so that the flow switch detects a flow or the level switch detects a decrease in level.

  In the electrodeionization apparatus 3, a cation exchange membrane and an anion exchange membrane are alternately arranged between a pair of electrodes to form a demineralization chamber and a concentration chamber, and the demineralization chamber is filled with an ion exchanger. An electrodeionization module is provided. The ion exchanger filled in the desalting chamber is usually a mixture of cation exchange resin and anion exchange resin (so-called mixed bed resin), or a mixture of cation exchange fiber and anion exchange fiber. Is used.

  A direct current voltage is applied to the electrodeionization device 3 from the power supply device 4. The DC voltage during normal operation is, for example, 300 volts.

  When the operation is resumed after the electrodeionization device 3 is stopped, the switching valve 7 is switched to the return line 9 side in advance. This operation is achieved, for example, by determining that the electrodeionization device 3 is stopped in the control unit 5 and controlling the switching valve 7 to switch to the return line 9 side. For example, the controller 5 determines that the start switch 6 is turned on (that is, determines the start of use of deionized water at the use point) and controls the switching valve 7 to switch to the return line 9 side. Is done.

  Next, when determining the ON state of the start switch 6, the control unit 5 sets the voltage of the power supply device 4 to a higher value than that during normal operation, for example, 350 volts based on this. In addition, when the control unit 5 determines that the start switch 6 is turned on, the control unit 5 operates a water supply pump (not shown) of the electrodeionization device 3 so that treated water is supplied from the treated water tank 2 to the electrodeionization device 3. As a result, deionized water is discharged from the deionized water line 8. When the switching valve 7 is switched to the return line 9 side, the deionized water returns from the return line 9 to the treated water tank 2 and is circulated from the treated water tank 2 to the electric deionizer 3. Is called. When the specific resistance of deionized water reaches a predetermined value, the switching valve 7 is switched to the use point side, the voltage of the power supply device 4 is also returned to normal (for example, 300 volts), and normal operation is performed.

  According to the present embodiment, at the time of start-up, a higher DC voltage is applied than during normal operation to increase the deionization speed and shorten the circulation operation time, thereby shortening the start-up time of the electrodeionization device 3. be able to.

  FIG. 2 shows a second embodiment of the pure water production apparatus of the present invention. In the second embodiment, a first level switch 10 and a second level switch 11 are provided in the treated water tank 2. The first level switch 10 functions as a level sensor for starting circulation operation, and the second level switch 11 functions as a level sensor for stop interlock that stops the electrodeionization device 3. An ultraviolet oxidation device 14 is provided downstream of the treated water tank 2, and a flow rate adjusting valve 13 is provided between the ultraviolet oxidation device 14 and the electrodeionization device 3.

  When the stored water level in the treated water tank 2 is lowered to a predetermined level, the first level switch 10 detects this, and based on this detection signal, the control unit 12 switches the switching valve 7 to the return line 9 side to circulate. Start driving. When the circulating operation is started, the flow rate adjustment valve 13 provided upstream of the electrodeionization device 3 is throttled by the control unit 12 to reduce the feedwater flow rate to the electrodeionization device 3 (the feedwater flow rate to the demineralization chamber is reduced). And a signal is sent from the control unit 12 to the power supply device 4 to lower the voltage applied to the power supply device 4 during normal operation. As described above, when the water storage level is lowered to a predetermined level, the circulation operation is automatically started, and the circulation operation is performed with the supply flow rate decreased and the applied voltage decreased. Therefore, even when the water storage level of the treated water tank 2 falls below a predetermined level, the energization of the electrodeionization device 3 is not stopped by switching to the circulation operation. As a result, the concentration gradient in the desalting chamber does not disappear, and the deionization of the treated water in the treated water tank 2 proceeds, so that the startup time at the next startup can be shortened.

  When the water storage level of the treated water tank 2 is restored to the original level by the operation of the reverse osmosis membrane device 1, the control unit 12 switches the switching valve 7 to the use point side, and applies the applied voltage of the power supply device 4 and the flow rate adjustment valve 13. The aperture is returned to normal and normal operation is performed.

  The second level switch 11 is for protecting the water supply pump and the electrodeionization module from damage. That is, when the water storage level further decreases from the position of the first level switch 10, the second level switch 11 detects this, and based on this detection signal, the control unit 12 sends a signal to the control unit 5, and the power supply device 4 And the operation is stopped by turning off the water supply pump.

  As described above, according to the embodiment of the present invention, when the electrodeionization apparatus 3 is started, the switching valve 7 is switched to the return line 9 side, and a higher DC voltage and / or DC current than during normal operation is applied. By applying the voltage, the time for the circulation operation can be shortened, and the deionized water can be quickly supplied to the use point accordingly.

  Moreover, according to this embodiment, when the water storage level of the treated water tank 2 falls below a predetermined level, the switching valve 7 is switched to the circulation operation based on the detection signal of the first level switch 10 (level sensor). Therefore, even when the water storage level drops below a predetermined level, the switching valve 7 is switched to the return line 9 to perform the circulation operation, thereby shortening the next startup time without stopping the electrodeionization device 3. can do. Moreover, although the lifetime of the ultraviolet lamp of the ultraviolet oxidizer 14 is reduced by repeatedly turning on and off as the electrodeionization apparatus 3 is started and stopped, this can be prevented in the present embodiment.

  Further, according to the present embodiment, when switching to the circulation operation, it is possible to realize energy saving during the circulation operation by restricting the flow rate adjustment valve 13 and lowering the applied voltage of the power supply device 4.

  As mentioned above, although embodiment of this invention was described, it only illustrated the specific example and does not specifically limit this invention, the reverse osmosis membrane apparatus 1, the treated water tank 2, the electrodeionization apparatus 3, and a power supply device 4. Specific configurations and arrangements of the switching valve 7, the control unit 5, the control unit 12, 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 Reverse osmosis membrane apparatus 2 Treated water tank 3 Electrodeionization apparatus 4 Power supply device 5 Control part 6 Starting switch 7 Switching valve 8 Deionized water line 10 1st level switch 11 2nd level switch 12 Control part 13 Flow control valve

Claims (2)

A reverse osmosis membrane device for treating water to be treated;
A treated water tank for storing treated water treated by the reverse osmosis membrane device;
An electrodeionization apparatus for treating the treated water supplied from the treated water tank;
A deionized water line for discharging deionized water treated by the electrodeionization device;
A return line that branches off from the deionized water line and returns the deionized water to the treated water tank;
A switching valve that is provided at a branch portion between the deionized water line and the return line, and switches between a circulating operation for flowing deionized water to the return line and a non-circulating operation for flowing to the deionized water line;
A power supply device for applying a DC voltage and / or a DC current to the electrodeionization device;
A level sensor for water storage level detection provided in the treated water tank;
And a controller that switches the switching valve to a circulating operation based on a detection signal of the level sensor when the water storage level drops below a predetermined level. A flow rate adjusting valve for adjusting the flow rate to the electrodeionization device;
When the control unit switches the switching valve to the circulation operation, the flow restrictor adjustment valve, and the power supply pure water production apparatus according to claim 1, wherein the performing control to lower the voltage applied .

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