KR102602540B1 - Ultrapure water production device and method of operating the ultrapure water production device - Google Patents

Abstract

The ultrapure water production device (1) includes a primary pure water system (2) and a subsystem (3). The primary pure water system (2) has a reverse osmosis membrane (RO) device (4) and a regenerative mixed-bed ion exchange device (5), and at the downstream of the regenerative mixed-bed ion exchange device (5), boron concentration measurement is performed. It is provided with a boron monitor (6) and an electric deionization device (7) as means. The subsystem 3 has a UV oxidation device 9, a non-regenerative mixed-bed ion exchange device 10, and an ultrafiltration membrane 11. Then, the boron concentration of the primary pure water (W1) is continuously monitored by the boron monitor 6, and the product of the boron concentration [B] of the primary pure water (W1) and the boron removal rate of the electric deionization device 7 is calculated as the treated water ( Assuming the boron concentration [B1] of W2), the boron concentration of the water supplied to the subsystem (3) is continuously monitored. According to such an ultrapure water production device 1, it becomes possible to efficiently remove boron and quickly prevent its leakage.

Description

Ultrapure water production device and method of operating the ultrapure water production device

The present invention relates to an ultrapure water production device for producing ultrapure water used in the electronics industry, such as semiconductors and liquid crystals, and a method of operating this ultrapure water production device. In particular, it relates to an ultrapure water production device and method of operating the same that can efficiently remove boron and prevent its leakage.

Conventionally, ultrapure water used in the electronics industry, such as semiconductors, is produced by treating raw water with an ultrapure water production device consisting of a pretreatment system, a primary pure water system, and a subsystem for processing primary pure water.

In this ultrapure water production device, the pretreatment system is comprised of a flocculation, pressure flotation (sedimentation), filtration (membrane filtration) device, etc., and removes suspended substances and colloidal substances in raw water. In this process, polymeric organic substances, hydrophobic organic substances, etc. can be removed. In addition, the primary pure water system is basically equipped with a reverse osmosis (RO) membrane separation device and a regenerative ion exchange device (mixed bed type or 4-phase 5 tower type, etc.). The RO membrane separation device removes salts and ions. Removes viscous and colloidal TOC. In a regenerative ion exchange device, salts are removed and TOC components are removed by adsorption or ion exchange with an ion exchange resin.

Additionally, the subsystem is basically equipped with a low-pressure ultraviolet (UV) oxidation device, a non-regenerative mixed-bed ion exchange device, and an ultrafiltration (UF) membrane separation device, and the purity of the primary pure water is further increased to become ultrapure water. In a low-pressure UV oxidation device, TOC is decomposed into organic acids and CO ₂ by 185 nm ultraviolet rays emitted from a low-pressure ultraviolet lamp. And, organic matter and CO ₂ generated by decomposition are removed in a non-regenerative mixed-bed ion exchange device at the later stage. In the UF membrane separation device, fine particles are removed and effluent particles of the ion exchange resin are also removed.

In the subsystem of such a conventional ultrapure water production device, when weak ion components, especially boron ions, leak from the primary pure water system, they are removed in a non-regenerative mixed-bed ion exchange device. needs to be replaced once boron ions have been adsorbed to a certain extent. Recently, the boron concentration required for ultrapure water has been gradually lowering to 0.1 ppt or less. Since the removal efficiency of boron in the low concentration range is poor in non-regenerative mixed-bed ion exchange devices, non-regenerative water is required to reliably maintain the required boron water quality. There was a problem that the type mixed-bed ion exchange device needed to be replaced quickly, and the frequency of replacement was shortened. Therefore, as described in Patent Document 1, it is conceivable to install an electrical deionization device in the subsystem.

Japanese Patent Publication No. 7-8948

However, as described in Patent Document 1, when an electrical deionization device is installed in the subsystem, the subsystem processes high purity water close to ultrapure water, so it is difficult for electricity to flow and the electrical resistance for deionization increases. Therefore, there is a problem in that current efficiency is poor and the load on the electrodeionization device increases. In addition, considering the pressure resistance of the electric deionization device, the supply pressure of the water to be treated cannot be increased very much, and the discharge pressure of the treated water is smaller than the supply pressure, so the treatment at the downstream stage of the electric deionization device is difficult. Because it becomes unstable, the stability of water quality cannot be secured, and there is a problem of insufficient water pressure to supply ultrapure water to the point of use. Therefore, a separate supply device such as a booster pump is installed at the downstream of the electric deionization device, but there is a problem that it is necessary to take into consideration the treatment of the effluent from the booster pump, which easily leads to an increase in the size of the subsystem.

In addition, no matter what configuration the ultrapure water production device is made of, it is necessary to quickly detect boron leakage into the ultrapure water supplied from the subsystem, but since there is no means to measure the boron concentration at the 0.1ppt level on-site, the There is a problem that indexing is difficult.

The present invention was made in view of the above problems, and its purpose is to provide an ultrapure water production device capable of efficiently removing boron and quickly preventing its leakage. Additionally, the present invention aims to provide a method of operating this ultrapure water production device.

In view of the above object, the present invention firstly provides an ultrapure water production device having a primary pure water system and a subsystem including an ion exchange device and a UF membrane device for processing the primary pure water obtained from the primary pure water system, An ultrapure water production device is provided, which is located at the rear of the primary pure water system and at the front of the subsystem, and is equipped with a boron concentration measuring means and an electric deionization device (invention 1).

According to this invention (invention 1), the boron removal rate of the electric deionization device for primary pure water is measured in advance, and the boron concentration of the primary pure water is continuously monitored using a boron concentration measuring means. The boron detection level of boron detection means such as general-purpose boron monitors is 10 ppb, and the measured value is 1 ppb level, and the boron concentration detected by the boron concentration measurement means is multiplied by the boron removal rate of the electric deionization device to treat the water treated by the electric deionization device. It can be assumed that the boron concentration is . Since the boron concentration of the ultrapure water treated in the subsystem is at least smaller than the treated water of the electrical deionization device, the boron concentration of the ultrapure water treated in the subsystem is judged based on the boron concentration of the treated water of the electrical deionization device. If the boron concentration of the primary pure water is stable, continuous operation is continued, and the boron concentration of the treated water (ultrapure water) of the subsystem is accurately analyzed as appropriate. If the rate of increase increases, it is judged that the breakthrough of the ion exchange device of the subsystem is close. By replacing this, boron can be removed efficiently and boron leakage can be quickly prevented.

In the above invention (invention 1), it is preferable that the primary pure water system has a reverse osmosis membrane device and an ion exchange device (invention 2).

According to this invention (invention 2), boron can be efficiently removed in a primary pure water system.

In the above inventions (inventions 1 and 2), the electrodeionization device includes a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber partitioned by the cation exchange membrane and the anion exchange membrane. and a concentration chamber, wherein the desalting chamber and the enrichment chamber are filled with an ion exchanger, a concentrated water passage means for passing concentrated water through the enrichment chamber, and a concentrated water passage means for passing raw water through the desalination chamber to provide deionized water. It is desirable to have a means for taking out (invention 3).

According to this invention (invention 3), the electrical deionization device having this structure has a high boron removal rate and can maintain an almost constant removal rate, so that the concentration of boron detected by the boron concentration measuring means is determined by the electrical deionization device. The product multiplied by the boron removal rate can be accurately assumed as the boron concentration of the treated water of the electric deionization device.

In the above invention (invention 3), it is preferable that the concentrated water passing means flows deionized water that has passed through the desalting chamber as concentrated water (invention 4).

According to this invention (invention 4), by passing deionized water from the desalination chamber to the concentration chamber, the difference in ion concentration between the concentration chamber and the desalination chamber can be reduced because the ion components of the deionized water itself are traceable, thereby reducing the concentration of boron. Since the removal rate can be increased, there is no need to replace the ion exchange device of the subsystem for a long period of time.

In the invention (invention 4), the concentrated water passing means introduces the concentrated water into the concentration chamber from a side close to the deionized water outlet of the desalination chamber, and discharges the concentrated water from a side close to the raw water inlet of the desalination chamber. It is desirable to do so (invention 5).

According to this invention (invention 5), in the electric deionization device, the ion concentration decreases toward the side closer to the deionized water outlet in the deionization chamber, so, contrary to this, the deionized water is discharged from the side closer to the deionized water outlet into the concentration chamber. By supplying the ion concentration gap between the desalting room and the enrichment room, the gap between the desalting room and the enrichment room can be reduced throughout the desalting room and the enrichment room, and the effect of improving the removal rate of boron ions is significant, so the boron removal rate can be higher, so the subsystem There is no need to replace the ion exchange device for a long time.

Additionally, the present invention secondly has a primary pure water system, a subsystem including an ion exchange device and a UF membrane device for processing the primary pure water obtained from the primary pure water system, and is a downstream stage of the primary pure water system and the subsystem A method of operating an ultrapure water production device equipped with a boron concentration measuring means and an electric deionization device at the front end of the method, wherein ultrapure water is produced by continuously passing water to be treated through a primary pure water system and a subsystem, wherein the electric deionization device is used to produce ultrapure water. Provided is a method of operating an ultrapure water production device, characterized in that determining whether replacement of the ion exchange device of the subsystem is necessary or unnecessary is determined from the removal rate of boron ions and the boron concentration measured by the boron concentration measuring means (invention 6 ).

According to this invention (invention 6), the boron removal rate of the electrodeionization device for primary pure water is measured in advance, and the boron concentration of the primary pure water is continuously monitored using a boron concentration measuring means. The boron detection level of boron detection means such as general-purpose boron monitors is 10 ppb, and the measured value is 1 ppb level, and the boron concentration detected by the boron concentration measurement means is multiplied by the boron removal rate of the electric deionization device to treat the water treated by the electric deionization device. Assuming a boron concentration of , it is possible to determine whether exchange of the ion exchange device is necessary or unnecessary based on this boron concentration and the boron concentration of the ultrapure water of the subsystem.

In the above invention (invention 6), it is preferable that the primary pure water system has a reverse osmosis membrane device and an ion exchange device (invention 7).

According to this invention (invention 7), boron can be efficiently removed in a primary pure water system.

In the above inventions (inventions 6 and 7), the electrodeionization device includes a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber partitioned by the cation exchange membrane and the anion exchange membrane. and a concentration chamber, wherein the desalting chamber and the enrichment chamber are filled with an ion exchanger, a concentrated water passing means for flowing concentrated water into the enrichment chamber, and a means for flowing raw water into the desalting chamber to extract deionized water. It is desirable to have (Invention 8).

According to this invention (invention 8), by passing deionized water from the desalination chamber to the concentration chamber, the difference in ion concentration between the concentration chamber and the desalination chamber can be reduced because the ion components of the deionized water itself are traceable, so that the boron Since the removal rate can be increased, there is no need to replace the ion exchange device of the subsystem for a long period of time.

In the above invention (invention 8), it is preferable that the concentrated water passing means introduces a part of the treated water that has passed through the desalination chamber as the concentrated water (invention 9).

According to this invention (invention 9), by passing deionized water from the desalting chamber through the concentrating chamber, the difference in ion concentration between the concentrating chamber and the desalting chamber can be reduced because the ion components of the deionized water itself are traceable, thereby reducing the concentration of boron. Since the removal rate can be increased, there is no need to replace the ion exchange device of the subsystem for a long period of time.

In the invention (invention 9), the concentrated water is introduced into the concentration chamber from a side close to the deionized water outlet of the desalination chamber, and is discharged from a side close to the raw water inlet of the desalination chamber of the concentration chamber. Preferred (Invention 10).

According to this invention (invention 10), in the electric deionization device, the ion concentration decreases toward the side closer to the deionized water outlet in the deionization chamber, so, contrary to this, the deionized water is discharged from the side closer to the deionized water outlet into the concentration chamber. By supplying the ion concentration gap between the desalting room and the enrichment room, the gap between the desalting room and the enrichment room can be reduced throughout the desalting room and the enrichment room, and the effect of improving the removal rate of boron ions is significant, so the boron removal rate can be higher, so the subsystem There is no need to replace the ion exchange device for a long time.

According to the present invention, a boron concentration measuring means and an electric deionization device are installed at the downstream of the primary pure water system, the boron concentration of the primary pure water is continuously monitored by the boron concentration measuring means, and the boron concentration measured by the boron concentration measuring means is adjusted. Assuming that the product of the boron removal rate of the electric deionization device is the boron concentration of the treated water of the electric deionization device, and based on the boron concentration of the treated water of the electric deionization device, the secondary pure water (ultrapure water) treated in the subsystem Compared with the actual measured value of the boron concentration, if the actual measured value is greater than the predetermined value, by replacing the ion exchange device of the subsystem, the ion exchange device of the subsystem can be exchanged efficiently without causing leakage of boron. there is.

1 is a flow diagram showing an ultrapure water production apparatus according to a first embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view showing the configuration of an electric deionization device used in the ultrapure water production device according to this embodiment.
FIG. 3 is a schematic diagram showing the electrical deionization device of FIG. 2.
Fig. 4 is a flow chart showing an ultrapure water production apparatus according to a second embodiment of the present invention.

Hereinafter, an ultrapure water production apparatus according to the first embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a flow diagram showing an ultrapure water production device according to a first embodiment of the present invention. In FIG. 1, the ultrapure water production device 1 includes a primary pure water system 2 and a subsystem 3, The primary pure water system (2) has a reverse osmosis membrane (RO) device (4) and a regenerative mixed-bed ion exchange device (5), and at the downstream of the regenerative mixed-bed ion exchange device (5), boron concentration measurement is performed. It has a boron monitor 6 and an electric deionization device 7 as means, and this electric deionization device 7 is connected to the subsystem 3 through a nitrogen-sealed sub tank 8. And, the subsystem 3 includes a sub tank 8, a supply pump P, a UV oxidation device 9, a non-regenerative mixed bed ion exchange device 10, and an ultrafiltration membrane (UF membrane) 11. It is configured to flow back from the ultrafiltration membrane (UF membrane) 11 to the sub tank 8 via the use point (UP).

In this ultrapure water production device 1, as the boron monitor 6, a general-purpose boron monitor capable of measuring a boron concentration level of 10 ppb and a measured value of 1 ppb level can be used, for example, sold by Central Science Co., Ltd. SIEVERS ultrapure water measurement online boron analyzer is available.

Additionally, as the electrical deionization device 7, one having the structure shown in FIGS. 2 and 3 can be suitably used.

In FIG. 2, the electrodeionization device 7 has a plurality of anion exchange membranes 23 and cation exchange membranes 24 alternately arranged between electrodes (anode 21, cathode 22) to form a concentration chamber 25. and desalting chambers 26 are formed alternately, and in the desalting chamber 26, ion exchangers (anion exchangers and cation exchangers) made of ion exchange resins, ion exchange fibers, or graft exchangers are mixed or multi-layered. It is charged. Additionally, the concentration chamber 25, the anode chamber 27, and the cathode chamber 28 are also filled with an ion exchanger.

In this electric deionization device 7, water passage means (not shown) passes primary pure water (W1) of the regenerative mixed-bed ion exchange device (5) through the deionization chamber (26) to extract treated water (W2). And, a concentrated water passage means (not shown) is installed to pass the concentrated water W3 through the concentration chamber 25. In this embodiment, the concentrated water W3 is passed through the treated water of the desalination chamber 26 ( It is introduced into the concentration chamber 25 from the side close to the outlet of W2 and is discharged from the side close to the raw water inlet of the desalination chamber 26, that is, the distribution of primary pure water (W1) in the desalination chamber 26. It is configured to introduce concentrated water W3 into the enrichment chamber 25 from the opposite direction and discharge concentrated waste water W4.

Specifically, as shown in FIG. 3, a part of the treated water W2 obtained from the desalination chamber 26 is introduced into the concentration chamber 25 and the treated water W2 is used as the concentrated water W3, thereby increasing the ion concentration. It is preferable to use concentrated water (W3) with reduced .

Additionally, as the UV oxidation device 9 of the subsystem 3, a UV oxidation device that irradiates UV with a wavelength of around 185 nm commonly used in ultrapure water production equipment, for example, a UV oxidation device using a low-pressure mercury lamp, can be used. You can.

A method of operating an ultrapure water production device having the above-described configuration will be described. First, the water to be treated (W), which has been pretreated by a pretreatment means not shown as necessary, is supplied to the primary pure water system 2, followed by a reverse osmosis membrane (RO) device 4 and a regenerative mixed bed ion exchange device. Processed in (5). In the reverse osmosis membrane (RO) device 4, in addition to removing salts, ionic and colloidal TOC are removed. In the regenerative mixed-bed ion exchange device 5, in addition to removing salts, TOC components adsorbed or ion-exchanged by an ion exchange resin are removed to produce primary pure water (W1).

In this embodiment, the primary pure water (W1) of this regenerative mixed-bed ion exchange device (5) is monitored for boron concentration [B] by the boron monitor (6) with a boron detection level of 10 ppb and a measured value of 1 ppb. is continuously monitored. Then, after this primary pure water (W1) is treated in the electric deionization device (7), the obtained treated water (W2) is supplied to the sub tank (8).

At this time, the boron removal rate is calculated in advance by measuring the boron concentration in the treated water (W2) of the electric deionization device (7) when the existing primary pure water (W1) is treated. The boron removal rate of the electric deionization device 7 is preferably 99% or more, especially 99.99% or more. In particular, the electric deionization device as shown in FIGS. 2 and 3 described above is suitable for achieving a boron removal rate of 99.99% or more. And, the product of the boron concentration of the primary pure water (W1) and the boron removal rate of the electric deionization device (7) can be assumed to be the boron concentration [B1] of the treated water (W2) (e.g., the primary pure water (W1) If the boron concentration [B] of is 1 ppb or less and the boron removal rate of the electric deionization device 7 is 99.99%, the boron concentration [B1] of the treated water (W2) can be assumed to be 0.1 ppt or less). In this way, even if the boron concentration of the treated water (W2) supplied to the subsystem 3 is 1 ppb or less, it can be continuously monitored.

Subsequently, the treated water W2 supplied to the sub tank 8 is supplied and treated by the pump P. In the subsystem 3, treatment is performed using a UV oxidation device 9, a non-regenerative mixed-bed ion exchange device 10, and an ultrafiltration membrane 11. In the UV oxidation device 9, TOC is decomposed into organic acids and further to the CO ₂ level by ultraviolet rays with a wavelength of 185 nm emitted from a UV lamp. Decomposed organic acids and CO ₂ are removed in the non-regenerative mixed-bed ion exchange device (10) at the rear stage. In the ultrafiltration membrane 11, fine particles are removed and particles flowing out of the non-regenerative mixed-bed ion exchange device 10 are also removed, and secondary pure water (ultrapure water) (W5) is obtained. After this secondary pure water (W5) is supplied to the use point (UP), the unused portion is returned to the sub tank (8).

In the operation of this ultrapure water production device 1, the boron concentration of the secondary pure water (ultrapure water) W5, which is the treated water of the subsystem 3, is usually greater than the boron concentration [B1] of the treated water W2. Therefore, if the boron concentration [B1] of the treated water (W2) of the electric deionization device (7) is below the required water quality considering the reduction in the subsystem (3), it is considered a “problem” in terms of water quality. You can set it to “None” and operate continuously. For example, if the required boron quality of secondary pure water (W5) is 0.1 ppt, the boron removal rate of the electric deionization device (7) is 99.99%, and the subsystem (3) can reduce it to 1/10 or less, Continuous operation is possible if the boron concentration of primary pure water (W1) is 10 ppb or less.

In addition, the boron removal ability of the non-regenerative mixed-bed ion exchange device 10 decreases due to long-term use, making it easy for boron to leak into the secondary pure water (W5), so precise analysis of the secondary pure water (W5) is required on a regular basis. It is desirable to measure the actual boron concentration of the secondary pure water (W5). Then, by comparing the actual measured value of boron concentration [B2] with the boron concentration [B1] of the treated water (W2), the actual measured value of boron concentration [B2] is compared to the boron concentration [B1] of the treated water (W2). If the reduction rate tends to decrease, it is desirable to replace the non-regenerative mixed-bed ion exchange device 10 even before the boron concentration [B2] exceeds 0.1 ppt. In this way, leakage of boron into the secondary pure water (W5) can be prevented. Moreover, if the performance of the non-regenerative mixed-bed ion exchange device 10 actually tends to deteriorate, the non-regenerative mixed-bed ion exchange device 10 has to be replaced, so the replacement frequency is reduced, and thus the economic efficiency is excellent. .

In particular, in this embodiment, as the electric deionization device 7, a part of the treated water W2 is supplied to the concentration chamber 25 as concentrated water W3 in a direction opposite to the water flow direction of the desalination chamber 26. Since the water is passed in a counter-current manner and the concentrated waste water (W4) is discharged from the enrichment chamber (25) to the outside of the system, the concentrated water ( Since the ion concentration in W3) is low and the influence of concentration diffusion on the desalination chamber 26 is reduced, the boron removal rate is improved. In addition, since the water supply to the electric deionization device 7 is primary pure water (W1), there are few ions (for example, the electrical resistance is as large as 18 MΩ·cm), so a large amount of current is required, but the deionization chamber 26 By filling both sides of the concentration chamber 25 with an ion exchanger, the electrical resistance in the desalination chamber 26 and the concentration chamber 25 can be reduced, thereby reducing operating costs.

In addition, in this embodiment, since a nitrogen-sealed sub tank 8 is used, the dissolution of carbon dioxide and oxygen in the air is suppressed, and a decrease in the resistivity of the secondary pure water (W5) can be suppressed. .

Next, the ultrapure water production apparatus according to the second embodiment of the present invention will be described based on FIG. 4.

In the first embodiment described above, the ultrapure water production apparatus of the second embodiment includes a primary pure water system 2 and a subsystem 3, and the subsystem 3 includes a UV oxidation device 9 and an anion It is configured to include an exchange resin device 12, a degassing membrane 13, a non-regenerative mixed-bed ion exchange device 10, and an ultrafiltration membrane (UF membrane) 11.

By installing the anion exchange resin device 12 and the degassing membrane 13 in the subsystem in this way, the electric deionization device 7 itself is not airtight, so carbon dioxide gas or oxygen is not allowed to enter the primary pure water W1. Although there is a risk of small amounts being mixed, CO ₂ can be removed by the anion exchange resin device 12 and remaining gas components such as dissolved oxygen can be removed by the degassing membrane 13, so the dissolved gas components can be reduced. .

As mentioned above, the present invention has been described based on the above-described embodiments, but the present invention is not limited to the above-mentioned embodiments and various modifications are possible, and the primary pure water system 2 and the subsystem 3 are components of the present embodiment. It is not limited to and can be configured in various configurations. For example, in the primary pure water system 2, the reverse osmosis membrane (RO) device 4 may be arranged in two stages in series. In addition, in the first embodiment, the UV oxidation device 9 is installed in the subsystem 3, but the UV oxidation device 9 does not need to be installed depending on the case. Additionally, as the sub tank 8, a nitrogen-sealed tank was used, but a normal sub tank may be used, and in some cases, the sub tank 8 may not be used. In addition, other water quality analysis means such as a resistivity meter are installed to measure the water quality of the secondary pure water (W5), and the water quality of the secondary pure water (W5) is measured on-site, and when the specific resistance falls below a predetermined set value, the water quality is measured. The regenerative mixed-bed ion exchange device 10 may be replaced.

Example

Hereinafter, the present invention will be described in more detail through examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]

The water (water to be treated) (W) from Yoshida-cho, Haibara-gun, Shizuoka Prefecture was treated with a primary pure water system (2) consisting of a reverse osmosis membrane (RO) device (4) and a regenerative mixed-bed ion exchange device (5). . The boron concentration of this primary pure water (W1) was measured with the boron monitor (6), and it was treated with the electric deionization device (7), and the treated water (W2) was stored in the sub tank (8). The treated water (W2) in this sub tank (8) is filtered through a UV oxidation device (9), an anion exchange resin device (12), a degassing membrane (13), a non-regenerative mixed bed ion exchange device (10), and an ultrafiltration membrane (UF). The membrane (11) was treated with water through the subsystem (3) equipped in this order to produce secondary pure water (W5).

Additionally, as the electrical deionization device 7, the following was used.

Electric deionization device: KCDI-UPz manufactured by Kurita Industry Co., Ltd., the desalination chamber 26, the concentration chamber 25, and the electrode chambers 27 and 28 are filled with ion exchange resin, and a portion of the treated water (W2) Water is passed through the concentration chamber (25) in a countercurrent manner, and the boron removal rate is over 99.99%.

During the operation of this ultrapure water production device, the value of the boron monitor 6 was stable at 1 to 5 ppb, and the boron concentration of the treated water (W2) was estimated to be 0.1 ppt or less, so it was operated continuously. The boron concentration of this treated water (W2) was precisely analyzed once a month, and the boron concentration was stable at 0.1 ppt or less, and the boron concentration of the secondary pure water (W5) was also 0.1 ppt or less. In addition, the resistivity value of the secondary pure water (W5) is approximately 18.2 MΩ·cm, which is stable even after 3 years at the ultrapure water level, and the non-regenerative mixed-bed ion exchange device 10 of the subsystem 3 for 3 years. Exchange was unnecessary.

[Comparative Example 1]

In Example 1, monitoring was performed by installing a boron monitor 6 at the rear of the non-regenerative mixed-bed ion exchange device 10 without using the electric deionization device 7.

During the operation of this ultrapure water production device, the value of the boron monitor 6 exceeded 1 ppb for 3 weeks, so the non-regenerative mixed-bed ion exchange device 10 needed to be replaced.

[Comparative Example 2]

In Example 1, a boron monitor 6 was installed and monitored at the rear of the non-regenerative mixed-bed ion exchange device 10 of the subsystem 3, but the boron concentration could not be detected, so the non-regenerative horn It was difficult to determine the exchange time due to the breakthrough of the common sense ion exchange device 10.

[Comparative Example 3]

The same as Example 1, except that the electric deionization device 7 was not used in the primary pure water system 2, and the electric deionization device was placed after the UV oxidation device 9 in the subsystem 3. Then, monitoring was performed using the boron monitor (6).

During the operation of the ultrapure water production equipment as described above, the value of the boron monitor 6 was stable at 1 to 5 ppb, but the boron concentration in the influent water of the subsystem 3 was large, and the boron concentration installed in the subsystem 3 was high. Since the water pressure of the treated water in the electric deionization device is low and not stable, treatment in the anion exchange resin device 12 installed at this stage, etc. is also not stable, and for this reason, secondary pure water (W5) is used once a month. The variation in boron concentration in precise analysis was large, making it difficult to judge the exchange time due to breakthrough of the non-regenerative mixed-bed ion exchange device 10. In addition, a decrease in the performance of the electrical deionization device, which appears to be due to the influence of oxidizing substances generated in the UV oxidation device 9, was confirmed.

1 Ultrapure water production device 2 Primary pure water system
3 Subsystem 4 Reverse Osmosis Membrane (RO) Unit
5 Regenerative mixed bed ion exchange device 6 Boron monitor (means for measuring boron concentration)
7 Electric deionization device 8 Sub tank
9 UV oxidation device 10 Non-regenerative mixed bed ion exchange device
11 Ultrafiltration membrane (UF membrane) 12 Anion exchange resin device
13 Degassing membrane W treated water
W1 primary pure water W2 treated water
W3 concentrated water W4 concentrated drain
W5 secondary pure water (ultra pure water)

Claims (10)

An ultrapure water production device having a primary pure water system and a subsystem including an ion exchange device and a UF membrane device for processing the primary pure water obtained from the primary pure water system, wherein boron is added at the rear end of the primary pure water system and at the front end of the subsystem. a concentration measuring means and an electric deionization device;
Assuming that the product of the previously measured boron removal rate of the electric deionization device for the primary pure water and the boron concentration of the primary pure water measured by the boron concentration measuring means is the boron concentration of the water supplied to the subsystem, means for determining whether replacement of the ion exchange device of the subsystem is necessary or unnecessary by comparing the boron concentration of the feed water to the subsystem with the boron concentration of secondary pure water processed by the subsystem;
An ultrapure water production device comprising: In claim 1,
An ultrapure water production device, wherein the primary pure water system has a reverse osmosis membrane device and an ion exchange device. In claim 1 or claim 2,
The electrical deionization device is provided with a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber and a concentration chamber partitioned by the cation exchange membrane and the anion exchange membrane. The enrichment chamber is filled with an ion exchanger, and has a means for passing concentrated water through the enrichment chamber and a means for flowing raw water into the deionization chamber to extract deionized water. Ultrapure water production device. In claim 3,
An ultrapure water production device, wherein the concentrated water passing means passes deionized water that has passed through the desalting chamber as concentrated water. In claim 4,
An ultrapure water production device, wherein the concentrated water passage means introduces the concentrated water into the concentration chamber from a side close to the deionized water outlet of the desalination chamber and discharges the concentrated water from a side close to the raw water inlet of the desalination chamber. It has a primary pure water system and a subsystem including an ion exchange device and a UF membrane device for processing the primary pure water obtained from the primary pure water system, and a boron concentration measuring means and an electric device at the rear of the primary pure water system and at the front of the subsystem. A method of operating an ultrapure water production device equipped with a deionization device,
When producing ultrapure water by continuously passing the water to be treated through the primary pure water system and the subsystem, the boron removal rate with respect to the primary pure water of the electric deionization device measured in advance and the boron concentration measured by the boron concentration measuring means By assuming the product of the boron concentration of the primary pure water to be the boron concentration of the feed water to the subsystem, and comparing the boron concentration of the feed water to the subsystem with the boron concentration of the secondary pure water treated by the subsystem, A method of operating an ultrapure water production device, characterized in that determining whether replacement of the ion exchange device of the subsystem is necessary or unnecessary. In claim 6,
A method of operating an ultrapure water production device, wherein the primary pure water system has a reverse osmosis membrane device and an ion exchange device. In claim 6 or claim 7,
The electrical deionization device is provided with a cathode and an anode, a cation exchange membrane and an anion exchange membrane disposed between the cathode and the anode, and a desalting chamber and a concentration chamber partitioned by the cation exchange membrane and the anion exchange membrane, the desalting chamber and The operation of an ultrapure water production device, characterized in that the concentration chamber is filled with an ion exchanger, and the ultrapure water production device has means for passing concentrated water through the concentration chamber and means for flowing raw water into the desalination chamber to extract deionized water. method. In claim 8,
A method of operating an ultrapure water production device, wherein the concentrated water passing means introduces a portion of the treated water that has passed through the desalination chamber as the concentrated water. In claim 9,
A method of operating an ultrapure water production device, characterized in that the concentrated water is introduced into the concentration chamber from a side close to the deionized water outlet of the desalination chamber, and is discharged from the side of the concentration chamber close to the raw water inlet of the desalination chamber. .