JP2021126624A - Ultrapure water production device and ultrapure water production method - Google Patents

Abstract

To inexpensively, stably and reliably produce ultrapure water of high purity that sufficiently meets water quality requirements, regardless of variation in the amount and quality of the water, while also achieving a reduced device installation area.SOLUTION: An ultrapure water production device is provided with: a pretreatment system that treats raw water; a primary water purification system that treats the water treated by the pretreatment system; and a subsystem that treats the water treated by the primary water purification system. The primary water purification system comprises, as constituent devices, at least a reverse osmosis membrane separation device, a degassing device, an ultraviolet oxidation device, and an ion exchange device in this order. The ultrapure water production device has a monitor that monitors the amount and/or quality of the water in the primary water purification system, and control means that controls operation conditions of one or more of the constituent devices according to a value detected by the monitor.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultrapure water production apparatus and an ultrapure water production method.

Ultrapure water, which is used in large quantities as cleaning water in the manufacturing process of electronic devices, especially semiconductors, is an ultrapure water production system consisting of a pretreatment system, a primary pure water system, and a subsystem, and is raw water (industrial water). , Tap water, well water, used ultrapure water discharged from the electronic device manufacturing process, etc.).

Conventionally, the following have been proposed as such an ultrapure water production system.

Patent Document 1 includes a primary pure water system and a subsystem for treating treated water of the primary pure water system, and at least the primary pure water system is provided with a reverse osmosis membrane separation device for producing ultrapure water. In the apparatus, an ultrapure water production apparatus characterized in that the reverse osmosis membrane separator installed in the primary pure water system is a high-pressure reverse osmosis membrane separator and is installed in a single stage has been proposed. ing.
Patent Document 2 includes an ultrapure water system having a pretreatment system, a primary pure water system for treating pretreated water treated by the pretreatment system to obtain primary pure water, and a subsystem for treating primary pure water. In the water production device, the primary pure water system is configured to be connected in the order of a reverse osmosis membrane separation device, a degassing device, an electrodeionization device, an ultraviolet oxidation device, and a non-regenerative ion exchange device. An ultrapure water production apparatus characterized by the above has been proposed.
According to Patent Document 3, in an ultrapure water production apparatus including a primary pure water system and a secondary pure water system, the primary pure water system includes a two-bed, three-tower type ion exchange apparatus, a reverse osmosis membrane apparatus, and a 180 to 190 nm diameter. A combination of an ultraviolet irradiation device equipped with a low-pressure ultraviolet lamp that irradiates ultraviolet rays including a wavelength and a mixed-bed ion exchange device is provided along the flow path, and the secondary pure water system includes a wavelength of 180 to 190 nm. An ultrapure water production device has been proposed, characterized in that at least one pair of an ultraviolet irradiation device equipped with a low-pressure ultraviolet lamp that irradiates ultraviolet rays and a mixed-bed ion exchange device is provided along the flow path. There is.
In Patent Document 4, in an ultrapure water production apparatus including a pretreatment system, a primary pure water system and a secondary pure water system, the primary pure water system and the secondary pure water system are each provided with a wavelength of 180 to 190 nm. An ultrapure water production device has been proposed, characterized in that at least one combination of an ultraviolet irradiation device equipped with a low-pressure ultraviolet lamp that irradiates containing ultraviolet rays and a mixed-bed ion exchange device is provided along the flow path. There is.

Japanese Unexamined Patent Publication No. 2012-245439 Japanese Unexamined Patent Publication No. 2003-266097 Japanese Unexamined Patent Publication No. 2004-25184 Japanese Unexamined Patent Publication No. 7-75780

In recent years, with the increasing integration of electronic devices such as semiconductors and the miniaturization of circuit patterns, the current situation is that the demand for improving the water quality of ultrapure water used as cleaning water is further increasing.
In the ultrapure water production equipment or the ultrapure water production system, it is the primary pure water system that determines the reached water quality and water quality stability at the point of use.
As the device configuration of the primary pure water system, a reverse osmosis membrane separator, a degassing device, and an ion exchange device are generally installed in a single stage. There is a problem that cannot be dealt with by the device configuration of such a general primary pure water system.

For this reason, in recent state-of-the-art semiconductor factories and the like, the primary pure water system includes a reverse osmosis membrane separation device and / or an ion exchange device (hereinafter, "ion exchange tower") as shown in (A) and (B) below. The same) is installed in multiple stages to improve the purity of the obtained ultrapure water.

(A) Multi-stage RO system incorporating a plurality of reverse osmosis membrane (RO membrane) separation devices Specifically, the following device configuration with 7 constituent units can be mentioned.
Reverse osmosis membrane (RO membrane) separator → Mixed bed type ion exchange device (MB) → UV sterilizer (UVst) → Reverse osmosis membrane (RO membrane) separator → UV oxidizer (UVox) → Non-regenerative ion exchange device → Deaerator (MDG)
(B) Multi-stage electroregenerative ion exchange pure water apparatus (CDI) system incorporating a plurality of electroregenerative deionizers Specifically, the following apparatus configuration with 6 constituent units can be mentioned.
Reverse osmosis membrane (RO membrane) separator → Reverse osmosis membrane (RO membrane) separator → Degassing device (MDG) → Ultraviolet oxidizing device (UVox) → Multi-stage electroregenerative ion exchange pure water device (CDI) → Multi-stage electroregeneration Type ion exchange pure water device (CDI)

Here, the term "unit" as used herein refers to an apparatus capable of performing one or more of "desalination", "deaeration", and "organic substance removal", which are the main purposes of treatment in a primary pure water system. Meaning, the number of constituent units means the number of units provided in a system, for example, a primary pure water system.

For example, the pretreated water obtained by treating raw water (industrial water, tap water, well water, used ultrapure water discharged from the electronic device manufacturing process, etc.) by a pretreatment system can be used as the above (A), ( By treating with a primary pure water system such as B), the specific resistance is 18 MΩcm or more, the TOC (Total Organic Carbon) concentration is 2 μg / L or less, the boron (B) concentration is 1 ng / L or less, and the silica (SiO ₂ ) concentration is 0. It is possible to obtain primary pure water having a high purity of 1 μg / L or less (treated water of the primary pure water system, that is, outlet water of the primary pure water system).

However, since the primary pure water system such as (A) and (B) has a large number of constituent units, the equipment installation area (footprint) is large, and the equipment cost (initial cost) and operating cost (running cost) are large. There is a problem that the cost becomes high.

In addition, the required level of water quality of ultrapure water is expected to increase more and more in the future, the number of units of the primary pure water system will increase further, and the most severe expected water quality will be maintained and supplied. Operation will be performed under excessive operating conditions so that stable water quality can be maintained even under conditions. Moreover, once the operating conditions are decided, pure water will continue to be supplied without changing the amount of water supplied, so even if the production volume of semiconductor factories etc. decreases and the required amount of ultrapure water decreases, a certain amount Excess ultrapure water is drained in order to continue supplying pure water, and treatment is performed again for recovery and reuse, resulting in an unnecessarily high cost.

The present invention has been made in view of the above circumstances, and is capable of producing high-purity ultrapure water that sufficiently satisfies the required water quality, regardless of fluctuations in the amount and quality of water, while suppressing the installation area of the apparatus and at low cost. It is an object of the present invention to provide an ultrapure water production apparatus and an ultrapure water production method capable of stably and reliably producing.

The present inventors install appropriate devices in the primary pure water system provided in the ultrapure water production device in an appropriate order, and then control the operating conditions of these devices according to fluctuations in water quality and / or water volume. By doing so, it has been found that it is possible to inexpensively, stably and reliably produce high-purity ultrapure water that sufficiently satisfies the required water quality while reducing the number of constituent units.
That is, in the present invention, the primary pure water system is a 4-unit primary pure water system including a reverse osmosis membrane separator, a degassing device, an ultraviolet oxidizing device, and an electroregenerative ion exchange device in this order. , Water quantity and / or a monitor to monitor the water quality is provided, and for example, in order to suppress the fluctuation of the water quality caused by changing the supply water quantity according to the required production quantity, the operation of each unit is performed based on the signal from the monitor. Provide control means to automatically change the conditions and keep the water quality stable.

The present invention has been achieved based on such findings, and the gist of the present invention is as follows.

[1] The primary pure water system includes a pretreatment system for treating raw water, a primary pure water system for treating the treated water of the pretreatment system, and a subsystem for treating the treated water of the primary pure water system. However, it is an ultrapure water production device equipped with at least a back-penetrating film separation device, a degassing device, an ultraviolet oxidizing device, and an ion exchange device as constituent devices in this order, and the amount and / or water quality of water in the primary pure water system is determined. An ultrapure water production apparatus having a monitor to be monitored and a control means for controlling one or more operating conditions of the constituent apparatus according to a value detected by the monitor.

[2] The ultrapure water production apparatus according to [1], wherein the ion exchange device is an electroregenerative ion exchange device in which an electroregenerative deionizer is connected in series in one or a plurality of stages.

[3] An ultrapure water production method for producing ultrapure water using the ultrapure water production apparatus according to [1] or [2].

[4] As the treated water of the ion exchange device, the treated water having a specific resistance value of 18 MΩcm or more, a TOC concentration of 2 μm / L or less, a boron concentration of 1 ng / L or less, and a silica concentration of 0.1 μg / L or less is obtained in [3]. The ultrapure water production method described.

According to the present invention, each unit is operated in an optimum state according to the amount of water even if the required amount of water is changed by a low-cost ultrapure water production device having a small number of constituent units and therefore a small device installation area. As a result, high-purity ultrapure water that fully satisfies the required water quality can be stably and reliably produced at low cost.
In addition, even with regard to fluctuations in water quality, by operating each unit in the optimum state in response to the fluctuations, high-purity ultrapure water that fully satisfies the required water quality can be stably and reliably inexpensively produced. Can be manufactured.

It is a block diagram which shows an example of embodiment of the primary pure water system of the ultrapure water production apparatus of this invention.

Hereinafter, modes for carrying out the present invention will be described. It should be noted that the embodiments described below show an example of typical embodiments of the present invention, and the scope of the present invention is not limited and interpreted by this.

The ultrapure water production apparatus of the present invention includes a pretreatment system, a primary pure water system, and a subsystem. An ion exchange device is provided in this order.
According to the ultrapure water production apparatus of the present invention and the ultrapure water production method of the present invention using the ultrapure water production apparatus, high-purity ultrapure water that sufficiently satisfies the required water quality can be obtained in the device installation area and further. It can be manufactured inexpensively, stably and reliably while suppressing equipment cost (initial cost) and operating cost (running cost).

In the following, the characteristic primary pure water system of the ultrapure water production apparatus of the present invention will be mainly described, but the configuration of the pretreatment system and the subsystem in the ultrapure water production apparatus of the present invention is not particularly limited. No.
For example, as a pretreatment system, raw water (industrial water, tap water, well water, used ultra-pure that is discharged from the electronic device manufacturing process) by agglomeration, pressure flotation (precipitation), filtration (film filtration), etc. Examples thereof include a system for removing suspended substances and colloidal substances in water, etc., as well as high molecular weight organic substances and hydrophobic organic substances.
In addition, the subsystem is equipped with a low-pressure ultraviolet oxidizing device, an ion-exchanged pure water device, and an ultrafiltration membrane separation device, and further enhances the purity of the pure water obtained by the primary pure water system to obtain ultrapure water. Can be mentioned. In the low-pressure ultraviolet oxidizing device in the subsystem, the TOC is decomposed into _{organic acids and even CO 2} by the ultraviolet rays having a wavelength of 185 nm emitted from the low-pressure ultraviolet lamp. The organic matter and CO ₂ produced by the decomposition are removed by the ion exchange pure water device in the subsequent stage. In the ultrafiltration membrane separation device, fine particles are removed, and outflow particles of the ion exchange pure water device are also removed.

[Device configuration of primary pure water system]
The primary pure water system of the ultrapure water production apparatus of the present invention is a system having only 4 units, which includes a reverse osmosis membrane separating apparatus, a degassing apparatus, an ultraviolet oxidizing apparatus, and an ion exchange apparatus in this order. .. The primary pure water system is an ion in treated water (pretreated water) obtained by treating raw water (industrial water, tap water, well water, used ultrapure water discharged from the electronic device manufacturing process, etc.) by the pretreatment system. And remove organic components.
The water quality of the ultrapure water produced by the ultrapure water production apparatus of the present invention is, for example, the primary of (A) and (B) described above, even though the primary pure water system has only 4 units. Water quality equal to or better than the water quality of ultrapure water produced by an ultrapure water production device equipped with a primary pure water system in which a back-penetration membrane separator and / or an ion exchange device is installed in multiple stages like a pure water system. Can have.
Therefore, the ultrapure water produced by the ultrapure water production apparatus of the present invention is a high-purity ultrapure water that sufficiently satisfies the required water quality.

Hereinafter, each component of the primary pure water system according to the present invention will be described.

<Reverse osmosis membrane separation device>
The reverse osmosis membrane separation device according to the embodiment of the present invention removes salts as well as organic substances. As the reverse osmosis membrane separation device, a reverse osmosis membrane separation device conventionally used for desalination of seawater, for example, a high-pressure reverse osmosis membrane separation device having an operating pressure of about 0.2 to 7.0 MPa can be used. The shape of the reverse osmosis membrane may be any shape as long as it achieves the object of the present invention and exerts its effect, and examples thereof include a spiral shape, a hollow fiber shape, and a flat membrane shape. Be done.

<Degassing device>
The degassing device according to the embodiment of the present invention removes IC (inorganic carbon) and dissolved oxygen.
The reason why the degassing device (degassing device) is provided after the reverse osmosis membrane separation device is as follows.
That is, when a degassing device is provided in front of the reverse osmosis membrane separation device, the degassing membrane or filler (vacuum degassing) provided in the degassing device due _{to the turbidity existing in the raw water or Al, SiO 2, etc.} The filler in the equipment, etc.) may be contaminated and the degassing efficiency may decrease. Since these turbid substances or Al, SiO _2, etc. can be removed by the high-pressure reverse osmosis membrane separation device, the permeated water is passed through the degassing device after being treated by the high-pressure reverse osmosis membrane separation device. , It is possible to prevent a decrease in degassing efficiency.

The reason for installing the degassing device in front of the ion exchange device and the ultraviolet oxidizing device is as follows.
That is, the IC (inorganic carbon) component that can be removed by the degassing device becomes a radical scavenger for the ultraviolet oxidizing device and an anion load for the ion exchange device. Similarly, when there is an excess of dissolved oxygen that can be removed by the degassing device, the dissolved oxygen becomes a radical scavenger for the ultraviolet oxidizing device, similar to the IC (inorganic carbon) component described above. In addition, dissolved oxygen is a factor that causes oxidative deterioration of the resin for the ion exchange device.
Therefore, the degassing device needs to be installed in front of the ultraviolet oxidizing device and the ion exchange device.

The degassing device may be any decarboxylating device as long as it achieves the object of the present invention and exerts the effect of the present invention. For example, a decarboxylation tower, a membrane degassing device, a vacuum degassing device, and nitrogen. A degassing device, a catalytic resin deoxidizing device, or the like can be used.

<Ultraviolet oxidizing device>
The reason for installing the ultraviolet oxidizing device in the rear stage of the deaerator and in the front stage of the ion exchange device is as follows.
That is, in the ultraviolet oxidizing apparatus, organic substances in water (water to be treated) are decomposed into _{CO 2 and organic acids by the oxidizing power of OH radicals. The CO 2} or organic acid generated by the ultraviolet oxidizing device can be removed by the ion exchange device in the subsequent stage.

The ultraviolet oxidizing apparatus according to the embodiment of the present invention is not particularly limited as long as it emits light having a wavelength of 185 nm and achieves the object of the present invention and exerts the effect of the present invention.
In the embodiment of the present invention, as the ultraviolet oxidizing device, it is preferable to use an ultraviolet oxidizing device in which both the lamp and the outer tube are made of synthetic quartz having extremely few impurities from the viewpoint of organic matter decomposition efficiency.

<Ion exchange device>
The ion exchange device according to the embodiment of the present invention removes salts in water and removes charged organic substances.
The ion exchange device is not particularly limited as long as it achieves the object of the present invention and exerts the effect of the present invention, but the ion exchange device according to the embodiment of the present invention is a regenerative ion exchange device. Is preferable.
Examples of the regenerative ion exchange device include a two-bed, two-tower regenerative ion exchange device, a two-bed, one-tower regenerative ion exchange device, a mixed-bed regenerative ion exchange device, and an electroregenerative ion exchange device. Alternatively, an electroregenerative ion exchange device or the like connected in series in a plurality of stages can be mentioned. Among them, an electroregenerative ion exchange device that continuously regenerates without using a regenerated chemical, specifically, a regenerative ion exchange device in which one or a plurality of stages of an electroregenerative deionizer are connected in series is preferable.

<Monitor / control means>
The primary pure water system according to the ultrapure water production apparatus of the present invention includes a monitor for monitoring the amount and / or water quality of water, and one or more constituent devices according to the value detected by the monitor, that is, a reverse osmosis membrane separation device. It has a control means for controlling any one or more of a degassing device, an ultraviolet oxidizing device, and an ion exchange device. The monitor for monitoring the amount of water is not particularly limited, and may be a flow meter for the amount of treated water provided at the outlet of each component device or a flow meter for the amount of water supplied at the inlet. Further, examples of the monitor for monitoring the water quality include a pH meter and a resistivity meter for monitoring the water quality of the inlet water and the outlet water of each component device.
The control means has a calculation unit that performs a calculation for optimizing the operation state according to a measurement signal from the monitor, and automatically adjusts the operation conditions of each component device based on the calculation result.

The configuration of the monitor and the control means according to the present invention is not particularly limited, and examples thereof include the following.

For the reverse osmosis membrane separation device, a flow meter, a flow rate control valve for adjusting the flow rate, and a pump for injecting the chemical solution to be injected into the water supply of the reverse osmosis membrane separation device are provided. The injection volume is configured to be controllable.
For the degassing device, for example, the membrane degassing device, a vacuum pressure gauge, a pressure control valve capable of controlling the degree of vacuum, a flow meter for sweep gas such as nitrogen gas, and a control device such as a valve capable of controlling the gas flow rate are provided, and a calculation unit is provided. It is configured so that each can be controlled by the signal of.
The ultraviolet oxidizing device is provided with an output control device capable of controlling the output of ultraviolet rays, and is configured so that the output can be controlled by a signal from the arithmetic unit.
For an ion exchange device, for example, an electroregenerative ion exchange device, a flow meter, a flow control valve for adjusting the flow rate, and a current control device capable of controlling the current are provided, and the flow rate and the electric output can be controlled by a signal from the calculation unit. It is configured as follows.

The above-mentioned monitor, calculation unit, and control devices such as a flow meter, a flow control valve, a pressure control valve, a chemical injection pump, and a current control device are provided in a required number of one or more, and the number is not particularly limited. However, the flow control valves and pumps that monitor the water quality and flow rate, process the signals from the monitors, and control the flow rate and the injection amount of the chemical solution by receiving the signals from the calculation units may be generally used. , Not particularly limited.

[Implementation of primary pure water system]
Hereinafter, embodiments of the primary pure water system according to the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a storage tank, and pretreated water from the pretreatment system is introduced from the pipe 11. Slime control agent from the pipe 12 to the pipe 11, a scale inhibitor from the pipe 13 is injected by the respective chemical feed pump P _1, P _2. Pretreated water in the storage tank 1 is introduced into the reverse osmosis membrane separation device 2 by a high-pressure pump P ₃ via a pipe 14, are membrane separation to permeate and retentate are extracted from each pipe 15, 16. A water supply pipe 14 of the reverse osmosis membrane separation apparatus 2, the injection pipe 17 of the pH adjusting agent is provided, pH adjusting agent is injected by the chemical feed pump P _4. The water supply pipe 14 is provided with _{a pH meter M 1} as a water quality monitor, a water supply flow meter FI ₁ , and a water supply pressure meter PI _1. The permeated water pipe 15 is provided with a flow meter FI ₂ , a treated water flow rate control valve V ₁ and a treated water pressure gauge PI ₂ , and the concentrated water pipe 16 is provided with a flow meter FI ₃ and a concentrated water flow control valve V _2. Has been done.

The concentrated water of the reverse osmosis membrane separator 2 is discharged from the pipe 16 to the outside of the system, and the permeated water is degassed from the pipe 15 (in the present embodiment, the membrane degassing in which the liquid chamber and the gas chamber are separated by the degassing membrane). It is sent to the air device) 3 and degassed. The degassed treated water is supplied from the pipe 17 to the ultraviolet oxidizing device 4.
In the deaerator 3, together with the nitrogen gas for the sweep from the pipe 18 into the gas chamber is introduced, that is evacuated through a pipe 19 by the vacuum pump P _4, deaeration of the water flowing through the fluid chamber Is done. The pipe 18 is provided with a nitrogen gas flow rate control valve V ₃ and a nitrogen gas flow meter FI ₄ . The vacuum drawing pipe 19 is provided with a _{pressure control valve V 4} and a vacuum pressure gauge PI _3.

Reference numeral 6 denotes a current control device that controls the amount of supply current of the ultraviolet oxidizing device 4. The treated water of the ultraviolet oxidizing device 4 is sent to the desalting chamber of the electroregenerative ion exchange device 5 via the pipe 20 for processing. The pipe 20 is provided with a desalination chamber inlet flow meter FI _{5 of the electroregenerative ion exchange device 5.} Reference numeral 7 denotes a current control device that controls the amount of supply current of the electroregenerative ion exchange device 5. Further, the inlet pipe 21 into the concentrating compartment of the electrodeionization ion exchange apparatus 5, respectively concentrating chamber inlet water flow control valve V ₅ and the outlet water flow control valve V ₆ is provided in the outlet pipe 22, the pipe 22 Is equipped with a concentration chamber outlet flow meter FI ₆ .

The desalted water (primary pure water) taken out from the desalting chamber of the electroregenerative ion exchange device 5 is sent to the subsystem via the pipe 23 and further processed to produce ultrapure water.
The primary pure water pipe 23 is provided with a desalination chamber outlet flow meter FI ₇ and a pressure gauge PI ₄ , as well as a resistivity meter M ₂ as a water quality monitor, a TOC meter M ₃ , a silica concentration meter M _4, and a silica concentration meter M 4. A boron densitometer M ₅ is provided.

In the primary pure water system of Fig. 1, _{the measured values of each monitor M 1} , M ₂ , M ₃ , M ₄ , M ₅ and the flow meters FI ₁ , FI ₂ , FI ₃ , FI ₄ , FI ₅ , FI ₆ , The measured values of FI ₇ , pressure gauges PI ₁ , PI ₂ , PI ₃ , and PI ₄ are input to the calculation unit of the control means (not shown), and the operation conditions suitable for the optimum operating state of each device are calculated by this calculation unit. Based on the calculation result, the control signal of the chemical injection pump, the flow rate control valve, and the current control device is output.

Hereinafter, a control method for controlling the operating conditions of each constituent device in response to fluctuations in the amount of water and water quality by the ultrapure water production device incorporating the primary pure water system shown in FIG. 1 will be specifically described.

Control Example I: If using water in sub-system increases to increase the output of the high-pressure pump P _3, increasing the inlet water of the reverse osmosis membrane separation apparatus 2 (water supply). In the inlet side reverse osmosis membrane separation apparatus 2 in accordance with the reverse osmosis membrane separation apparatus flowmeter FI _1, with dosing control of chemical feed pump P _1, P ₂ is performed, the value of the pH meter M ₁ is constant chemical feeding, chemical dosing pump P ₃ is controlled so that.
In the reverse osmosis membrane separation device 2, the concentrated water flow rate control valve V _{2 opens in accordance with the water supply flow meter FI 1,} and the amount of treated water in the reverse osmosis membrane separation device 2 is maintained while maintaining the balance of the water volume in the reverse osmosis membrane separation device 2. Increase (permeated water volume).

_{In the degassing device 3, the nitrogen gas flow rate control valve V 3} opens in response to the increase in the measured value of _{the treated water outlet flow meter FI 2} of the reverse osmosis membrane separation device 2, and the injection amount of nitrogen gas is increased. Further, the pressure control valve V ₄ is opened so that the vacuum pressure gauge V ₄ has a predetermined vacuum degree, the output of the vacuum pump P ₄ is increased, and the vacuum degree of the degassing device 3 is increased.

Since the amount of organic substances decomposed in a predetermined time increases as the amount of water increases, the ultraviolet oxidizing device 4 increases the supply current value by the current control device 6 of the ultraviolet oxidizing device 4 to promote the decomposition of organic substances.

_{The electroregenerative ion exchange device 5 monitors the concentrating chamber outlet flow meter FI 6} in response to an increase in the measured value of the desalination chamber inlet flow meter FI 5, while monitoring the concentrating chamber inlet water of the electroregenerating _{chamber inlet flow meter FI 5.} The flow rate control valve V ₅ is opened to increase the flow rate of concentrated water and adjust the balance of the amount of water in the electroregenerative ion exchange device 5. Further, as the flow rate at the inlet of the desalting chamber of the electroregenerative ion exchange device 5 increases, the amount of ions to be processed increases. Increase the current value.

When the amount of water used in the subsystem increases by the above operation, the amount of primary pure water produced as the treated water of the primary pure water system can be increased while maintaining the water quality according to the increased amount.

Control Example II: If water consumption in the subsystem is reduced to lower the output of the high-pressure pump P _3, reducing the inlet water of the reverse osmosis membrane separation apparatus 2 (water supply). In the reverse osmosis membrane separation apparatus 2 in the inlet side, in accordance with the reverse osmosis membrane separation apparatus flowmeter FI _1, together with the control of the chemical feed pump P _1, P ₂ of the dosing is performed, the value of the pH meter M ₁ is constant chemical feeding, chemical dosing pump P ₃ is controlled to be.
In the reverse osmosis membrane separation device 2, the concentrated water flow rate control valve V _{2 is closed in accordance with the water supply flow meter FI 1,} and the amount of treated water in the reverse osmosis membrane separation device 2 is maintained while maintaining the balance of the water volume in the reverse osmosis membrane separation device 2. Reduce (permeated water volume).

_{In the degassing device 3, the nitrogen gas flow rate control valve V 3} is closed in accordance with the decrease in the measured value of _{the treated water outlet flow meter FI 2} of the reverse osmosis membrane separation device 2, and the injection amount of nitrogen gas is reduced. Further, the pressure control valve V ₄ is closed so that the vacuum pressure gauge V ₄ has a predetermined vacuum degree, the output of the vacuum pump P ₄ is lowered, and the vacuum degree of the degassing device 3 is lowered.

When the amount of water in the ultraviolet oxidizing device 4 decreases, the amount of organic substances decomposed in a predetermined time decreases. Therefore, the current control device 6 of the ultraviolet oxidizing device reduces the supply current value to reduce excess electrical energy.

The electroregeneration type ion exchange device 5 is for the concentration chamber inlet water of the electroregeneration type ion exchange device while monitoring _{the concentration chamber outlet flow meter FI 6} according to the decrease in the measured value of _{the desalination chamber inlet flow meter FI 5.} The flow rate control valve V ₅ is closed to reduce the flow rate of concentrated water and adjust the water volume balance in the electroregenerative ion exchange device 5. Further, when the flow rate at the inlet of the desalting chamber of the electric regeneration type ion exchange device 5 decreases, the amount of ions to be processed decreases, so that the current control device 7 of the electric regeneration type ion exchange device 5 supplies the electric regeneration type ion exchange device 5 to the electric regeneration type ion exchange device 5. Reduce the current value to reduce excess electrical energy.

If the amount of water used in the subsystem decreases due to the above operation, the treated water of the primary pure water system is treated after maintaining the quality of the treated water with the minimum necessary chemical injection and electrical energy according to the reduced amount. The amount of primary pure water produced can be reduced.

Control example III: When the amount of water used in the subsystem is constant and the quality of the primary pure water deteriorates,
In control examples I and II, a control example is shown when the amount of water used in the subsystem fluctuates, but the amount of water used in the subsystem is constant and does not fluctuate (the desalination chamber outlet flowmeter of the electroregenerative ion exchange device 5). FI ₇ is constant), but when the water quality of the produced primary pure water fluctuates, for example, when the measured value of the water quality monitor deteriorates and the water quality deteriorates (for example, when the measured value of the _{resistivity ohmmeter M 2 decreases)} ) Can perform the following controls.

When the measured value of the resistivity meter M _{2 becomes low, the output of the high-pressure pump P 3} is increased to increase the amount of water supplied by the reverse osmosis membrane separation device 2 in order to increase the resistivity. In the reverse osmosis membrane separation apparatus 2 in the inlet side, in accordance with the feed water flow meter FI _1, with dosing control of chemical feed pump P _1, P ₂ is performed, so that the value of pH meter M ₁ is constant drug Note pump _{P 3} is controlled.
In the reverse osmosis membrane separation device 2, the flow rate control valve V ₂ is opened according to the value of the water supply flow meter FI ₁ increased here, the balance of the amount of water in the reverse osmosis membrane separation device 2 is changed, and the recovery rate of the treated water is changed. Increase the amount of treated water (permeated water amount) after lowering. By lowering the recovery rate of the treated water, the quality of the treated water of the reverse osmosis membrane separation device 2 can be improved.

_{In the degassing device 3, the nitrogen gas flow rate control valve V 3} opens in response to the increase in the measured value of _{the treated water outlet flow meter FI 2} of the reverse osmosis membrane separation device 2, and the injection amount of nitrogen gas is increased. Further, the pressure control valve V ₄ is opened so that the vacuum pressure gauge V ₄ has a predetermined vacuum degree, the output of the vacuum pump P ₄ is increased, and the vacuum degree of the degassing device 3 is increased.

Since the amount of organic substances decomposed in a predetermined time increases as the amount of water increases, the ultraviolet oxidizing device 4 increases the supply current value by the current control device 6 of the ultraviolet oxidizing device 4 to promote the decomposition of organic substances.

The electroregenerative ion exchange device 5 is for the concentration chamber inlet water of the electroregenerative ion exchange device while monitoring _{the concentration chamber outlet flow meter FI 6} in response to the increase in the measured value of _{the desalination chamber inlet flow meter FI 5.} The flow rate control valve V ₅ opens to increase the flow rate of concentrated water and change the balance of the amount of water in the electroregenerative ion exchange device 5 to improve the ion exchange efficiency. Further, since the amount of ions is increasing due to the deterioration of water quality, the current control device 7 of the electroregenerative ion exchange device 5 increases the supply current value to the electroregenerative ion exchange device 5 to improve the desalting efficiency.

By the above operation, it is possible to stably supply the primary pure water as the treated water of the primary pure water system after recovering the water quality in response to the deterioration of the water quality of the primary pure water.

According to the present invention, the data is analyzed from the signals of the flow meter and the water quality monitor so that the water quality becomes constant in the calculation unit according to the fluctuation of the water amount and the water quality, and the opening degree of the flow control valve and the chemical injection pump are analyzed. By controlling the output of the device and the current value of the ultraviolet oxidizing device and the electroregenerative ion exchange device, it is possible to suppress the electrical energy and stably supply the primary pure water that maintains a constant water quality.

In the ultrapure water production method of the present invention, using such an ultrapure water production apparatus of the present invention, as the primary pure water which is the treated water in the primary pure water system, the specific resistance value is 18 MΩcm or more and the TOC concentration is 2 μg / L. Hereinafter, treated water having a boron concentration of 1 ng / L or less and a silica concentration of 0.1 μg / L or less is obtained, and primary pure water of such water quality is further treated by a subsystem to have a specific resistance value of 18.2 MΩcm or more and TOC. It is preferable to produce ultrapure water having a concentration of 0.1 μg / L or less, a boron concentration of 1 ng / L or less, and a silica concentration of 0.1 μg / L or less.

1 Storage tank 2 Reverse osmosis membrane separation device 3 Degassing device 4 Ultraviolet oxidation device 5 Electric regeneration type ion exchange device

Claims (4)

It is provided with a pretreatment system for treating raw water, a primary pure water system for treating the treated water of the pretreatment system, and a subsystem for treating the treated water of the primary pure water system.
The primary pure water system is an ultrapure water production device including at least a reverse osmosis membrane separation device, a degassing device, an ultraviolet oxidizing device, and an ion exchange device as constituent devices in this order, and the amount of water in the primary pure water system. An ultrapure water production apparatus having a monitor for monitoring water quality and / or a control means for controlling one or more operating conditions of the constituent devices according to a value detected by the monitor. The ultrapure water production apparatus according to claim 1, wherein the ion exchange device is an electroregenerative ion exchange device in which an electroregenerative deionizer is connected in series in one or a plurality of stages. An ultrapure water production method for producing ultrapure water using the ultrapure water production apparatus according to claim 1 or 2. The ultrapure water according to claim 3, wherein as the treated water of the ion exchange device, treated water having a specific resistance value of 18 MΩcm or more, a TOC concentration of 2 μm / L or less, a boron concentration of 1 ng / L or less, and a silica concentration of 0.1 μg / L or less is obtained. Pure water production method.

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