JP2013255864A - Apparatus for producing purified water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for producing purified water, wherein in the primary purified water system, when performing treatment in water to be treated in which the anion component is included more than the cation component, the service life of a mix bed ion exchange unit is prolonged and excellent ion component removal performance is included.SOLUTION: An apparatus for producing purified water includes a pretreatment system and a primary purified water system. The primary purified water system includes a reverse osmosis membrane unit and a mix bed ion exchange unit arranged just behind the reverse osmosis membrane unit. The mix bed ion exchange unit mixes a strongly-acidic cation exchange resin with a strongly-basic anion exchange resin at 1/1.5 to 1/5 in an exchange capacity ratio represented by (the strongly-acidic cation exchange resin)/(the strongly-basic anion exchange resin), and is filled with the mixed exchange resins.

Description

  The present invention relates to a pure water production apparatus that extends the life of a mixed bed ion exchange apparatus.

  Conventionally, pure water has been used in the fields of semiconductor manufacturing and pharmaceutical manufacturing. Pure water uses raw water from well water, well water, washing wastewater, etc., and combines most of the ions with a pretreatment system that combines adsorption removal and filtration, reverse osmosis membrane treatment, ultrafiltration treatment, ion exchange treatment, etc. It is manufactured through a primary pure water system that removes components and total organic carbon (hereinafter also referred to as TOC) components. In addition, this pure water can be further purified through a secondary pure water system that combines ultra-violet irradiation treatment, ultrafiltration treatment, ion exchange treatment, etc. to remove extremely small amounts of ions and low-molecular organic substances. It has been broken.

In the ion exchange treatment of the primary pure water system and the secondary pure water system, various ion exchange resins such as a cation exchange resin, an anion exchange resin, and a chelate resin are used depending on the quality of the water to be treated and the pure water produced. An ion exchange device filled in a container is used. Among them, the mixed bed type ion exchanger filled with a mixture of a cation exchange resin and an anion exchange resin has a cation exchange resin and an anion exchange resin that are mixed almost uniformly at an exchange capacity ratio of 1/1, Since the same effect as passing through the cation exchange device and the anion exchange device alternately and infinitely is obtained and high-quality pure water can be obtained, it is often used.
As a mixed bed type ion exchange device, a regenerative type and a non-regenerative type are known, both of which treat the water to be treated, saturate the ion exchange resin and lower the removal capability, so the load due to the treatment is increased. It is necessary to perform regeneration processing and replacement accordingly.

In the primary pure water system, reverse osmosis is used to remove fine particles together with ion components at the front stage of the mixed bed ion exchanger in order to reduce the load on the mixed bed ion exchanger and obtain higher quality pure water. Regeneration treatment is easier than membrane devices and mixed bed type ion exchange devices, and reverse osmosis membranes are clogged by a small amount of turbidity remaining in the treated water (pretreated water) of the pretreated water system. It is used in combination with a two-bed / three-column type apparatus that is unlikely to occur.
Also, it is known that silica and boron are difficult to remove in the mixed bed type ion exchange device of the primary pure water system. When improving the boron removal rate, the mixed bed type ion exchange device and the boron selection are selected. It has also been proposed to use a combination of devices using a conductive resin. (For example, refer to Patent Document 1.)

  It is also known that organic matter leaks from the above-described ion exchange resin according to the amount of the ion exchange resin. In order to solve this problem, as a mixed bed type ion exchange device in a primary pure water system, a cation exchange resin and an anion exchange resin are filled at a predetermined mixing ratio, and water to be treated at a high temperature of 60 ° C. is passed through. Thus, a mixed bed type ion exchange apparatus in which leaking organic substances are reduced is described. (For example, see Patent Document 2.)

On the other hand, in the secondary pure water system, as a mixed bed type ion exchange device, in order to obtain ultra-pure water with ultra-high water quality, the ion exchange resin is not regenerated and the ion exchange resin is replaced or replaced for each container. A non-regenerative mixed-bed ion exchange apparatus (polisher) is used.
The treated water of the secondary pure water system has a very small ion concentration of 1/1000 or less, for example, compared to the pretreated water that is the inlet water of the primary pure water system. Before the ion exchange resin is saturated, it is exchanged as described above.

  The polisher used in the secondary pure water system is a mixture of strong acid cation exchange resin and strongly basic anion exchange resin used for the purpose of reducing sodium ion and TOC and the purpose of reducing silica concentration at a predetermined ratio. A polisher configured as described above has been proposed. (For example, see Patent Documents 3 and 4.)

In recent years, with the increase in the scale of pure water production equipment used for medical and semiconductor manufacturing, and the increase in the quality of pure water, it has been stable for a longer period of time for the purpose of simplifying operation management and reducing costs. Therefore, ion exchange resins that can produce pure water tend to be required.
In particular, in an apparatus for producing high-quality pure water, there are problems that frequent replacement and regeneration treatment are required, the amount of chemicals used is increased, and the treatment process is complicated. In order to increase the mechanical and chemical load on the exchange resin, there is a problem that the ion exchange resin is crushed to further shorten the life.
Further, the treated water immediately after the regeneration treatment or replacement has insufficient water quality, and the treated water cannot be used until the water quality is improved and stabilized. Therefore, measures such as circulating and reprocessing treated water that does not satisfy the required water quality to the previous stage and blowing it out are taken, and the increase in the frequency of regeneration treatment is a major factor in complicating operation management and increasing costs. There was also a problem of becoming.

  For these reasons, there has been a demand for a pure water apparatus that has an excellent ion removal capability and can reduce the frequency of regeneration treatment in the primary pure water system.

Japanese Patent Application Laid-Open No. 08-089956 Japanese Patent Laid-Open No. 4-293586 JP 2007-167816 A JP-A-5-285477

  The present invention has been made in order to solve the above-mentioned problem. In the primary pure water system, when the water to be treated has a larger amount of anion component than that of the cation component, the life of the mixed bed type ion exchange apparatus is improved. It is an object of the present invention to provide an apparatus for producing pure water that is extended and has an excellent ability to remove ionic components.

By the way, in the reverse osmosis membrane device of the primary pure water system, ion components such as magnesium and sodium are removed together with all organic carbon components and fine particles, and permeated water is obtained. In reverse osmosis membrane devices, monovalent ions are less likely to be removed than divalent ions, and anionic components are less likely to be removed than cationic components such as metal ions. In the reverse osmosis membrane device, carbon dioxide (carbon dioxide) dissolved without being ionized is hardly removed. For this reason, in the permeated water of the reverse osmosis membrane device, there are many anion components such as hydrogen carbonate ions (HCO ₃ ⁻ ) derived from carbon dioxide that remain without being removed, and as a whole, there are more than the cation components.

  Among the anion components, particularly weak electrolyte anions are not only easily removed by the reverse osmosis membrane apparatus, but also difficult to be adsorbed by the subsequent ion exchange resin. In addition, when other anions such as hydrogen carbonate ions derived from carbon dioxide coexist, they are separated and leak even if they are once adsorbed. For this reason, there is a risk of increasing the load on the subsequent stage or deteriorating the quality of pure water.

  The present inventors have a mixed bed type ion exchange apparatus that allows water to be treated to flow through the water to be treated, such as the permeated water of the reverse osmosis membrane device, which has more anionic components than the cationic components (hereinafter also referred to as “excessive anion”). The research focused on the mixing ratio calculated by the exchange capacity of the cation exchange resin and the anion exchange resin to be filled. As a result, the predetermined mixing ratio calculated by the exchange capacity is determined, the removal rate of the weak electrolyte anion component that is difficult to be adsorbed is improved, and the balance with the removal rate of the cation component is controlled, thereby controlling the mixed bed type ion. Knowing that the life of the exchange device is extended, the pure water production device of the present invention was completed.

According to this pure water production apparatus, the present inventors have improved the removal rate of trace dissolved boron and silica derived from raw water, which has been difficult to remove until now, and sodium ions that can be easily measured by lowering the specific resistance Was found to leak first.
In the present invention, unless otherwise specified, the mixing ratio of the cation exchange resin and the anion exchange resin is a value calculated from the exchange capacity. The “lifetime” of the ion exchange resin or ion exchange device refers to a period from the start of water flow until the specific resistance of the treated water becomes a predetermined value or less and the water flow is stopped.
“Pure water” refers to water having a specific resistance of 10.0 MΩ · cm or higher, and “primary pure water” refers to pure water having a specific resistance of 17.0 MΩ · cm or higher.

The first pure water production apparatus of the present invention is a pure water production apparatus comprising a pretreatment system and a primary pure water system, wherein the primary pure water system comprises a reverse osmosis membrane device and the reverse osmosis membrane device. The mixed bed type ion exchange apparatus is installed immediately after the mixed bed type ion exchange apparatus, wherein the strong acid cation exchange resin and the strong basic anion exchange resin are combined with the strong acid cation exchange resin / the strong basicity. It is characterized by being mixed and filled as an exchange capacity ratio indicated by an anion exchange resin of 1 / 1.5-1 / 5.
In the second pure water production apparatus of the present invention, the mixed bed type ion exchange apparatus comprises a strongly acidic cation exchange resin and a strongly basic anion exchange resin as the strongly acidic cation exchange resin / the strongly basic anion exchange resin. It is characterized by being mixed and filled in the exchange capacity ratio shown as 1 / 2.5-1 / 3.5.
The third pure water producing apparatus of the present invention is characterized in that the reverse osmosis membrane device is a two-stage reverse osmosis membrane device.
The 4th pure water manufacturing apparatus of this invention is characterized by the specific resistance of the to-be-processed water passed through the said mixed bed type ion exchange apparatus being 0.1-10 Mohm * cm.
The fifth deionized water production apparatus of the present invention is characterized in that a two-bed, three-column apparatus is included between the pretreatment system and the reverse osmosis membrane apparatus.
The 6th pure water manufacturing apparatus of this invention is characterized by including the deaeration apparatus in the front | former stage of the said reverse osmosis membrane apparatus.
The seventh deionized water production apparatus of the present invention comprises a specific resistance meter in the subsequent stage of the mixed bed type ion exchanger, and the mixed bed at any time when the specific resistance drops to less than 17.0 MΩ · cm. It is controlled to stop water flow to the ion exchange device.
The eighth pure water production apparatus of the present invention is provided with a secondary pure water system for further purifying the treated water in the primary pure water system at the subsequent stage of the primary pure water system. .

  According to the pure water production apparatus of the present invention, when treating water to be treated containing more anion components than cation components in the primary pure water system, the life of the mixed bed type ion exchange device is extended and excellent. Ion removal capability can be obtained. According to the pure water producing apparatus of the present invention, it is possible to reduce the regeneration frequency, simplify the operation management, and reduce the cost.

  According to the pure water production apparatus of the present invention, it is possible to measure the decrease in specific resistance due to leakage of sodium ions and easily manage the exchange time of the mixed bed type ion exchange resin.

It is a schematic block diagram which shows the pure water manufacturing apparatus of this invention. It is a graph which shows the amount of treated water per 1 L of mixed bed type ion exchange resins with which the mixed bed type ion exchange apparatus used for embodiment of this invention was filled. It is a graph which shows the relationship between the time from the start of water flow, and the specific resistance value in the pure water extract | collected at the outlet of the mixed bed type ion exchange apparatus in the pure water manufacturing apparatus of embodiment of this invention. It is a graph which shows the relationship between the time from the start of water flow, and the specific resistance of the manufactured pure water in the pure water manufacturing apparatus of the comparative example of this invention. It is a graph which shows the relationship between the time from the start of water flow, and the specific resistance of the manufactured pure water in the pure water manufacturing apparatus of the comparative example of this invention.

  The mixed bed type ion exchange apparatus used in the pure water production apparatus of the present invention, in which the mixing ratio calculated by the exchange capacity of the cation exchange resin and the anion exchange resin is changed, is 1 because the mixing ratio is 1/1. This is a new finding that is incompatible with the general technical understanding of mixed-bed ion exchangers that improve the ability to remove ion components in the next pure water system.

  Regarding the ion-removing ability of the ion-exchange resin, various factors such as factors such as weak ions that are not easily adsorbed and ionic components that are difficult to adsorb due to colloidalization are related in a complex manner. Therefore, many design changes and ingenuities have been made for ion exchange devices, and many types of ion exchange resins, such as the type, filling amount, and water flow rate, according to the quality of treated water and treated water and the required performance improvements, etc. Has been optimized.

  In spite of such optimization, the new findings as described above have not been found so far. The most important action of the mixed bed type ion exchange resin is the exchange between the cation exchange resin and the anion exchange resin. The mixing ratio calculated by the volume is almost uniformly mixed at 1/1, thereby obtaining the same effect as infinitely passing water through an infinite number of cation exchange devices and anion exchange devices. This is because it was generally understood that high-quality pure water can be produced.

  Therefore, conventionally, even when treating the water to be treated in which one of the cation component or the anion component is larger than the other, the mixed bed type ion exchange apparatus in which the mixing ratio calculated by the exchange capacity is 1/1. Based on the quality of the water to be treated and the exchange capacity of the ion exchange resin, based on the integrated flow rate until the equipment is shut down, etc. It was configured by optimizing factors other than the mixing ratio such as the amount.

  On the other hand, the pure water production apparatus of the present invention has the mixing ratio of each ion exchange resin calculated by the exchange capacity for the mixed bed type ion exchange apparatus for treating the water to be treated with excess anion in the primary pure water system. By optimizing, the life of the entire mixed bed type ion exchange resin is extended.

  In the mixed bed type ion exchange apparatus used in the pure water production apparatus of the present invention, the permeated water of the reverse osmosis membrane apparatus is particularly focused on anion excess, and has not been studied in the past among the factors affecting the ion removal ability. The mixing ratio calculated by the exchange capacity of cation exchange resin and anion exchange resin was investigated. Based on the concentration ratio of the cation component and the anion component in the water to be treated, the anion exchange resin can be made a mixing ratio calculated by the exchange capacity of the present invention, which is higher than that of the cation exchange resin, and the removal rate of the anion component can be improved. It was. In addition, by improving the ability to remove the anion component, it was possible to extend the life of the mixed bed ion exchange resin.

In order to improve the removal rate of the anion component, a method of increasing the total amount of the ion exchange resin while keeping the mixing ratio calculated by the exchange capacity at 1/1 may be considered.
However, when the ion exchange treatment is performed, the ion exchange resin may contain carbon chains due to oxidative degradation or the like due to water-soluble substances contained in the ion exchange resin from the beginning after the production of the ion exchange resin. A part of the ion exchange resin-derived material is eluted. In the method of increasing the amount of ion exchange resin, the amount of eluate increases, which may increase the load on the subsequent water treatment apparatus. In particular, there are many elutions of organic ion components from the anion exchange resin, which may cause an increase in the TOC concentration in the subsequent stage.

If water continues to flow through the mixed-bed ion exchange resin and the cation exchange resin is saturated, cation components such as sodium ions and potassium ions will leak, but if the anion exchange resin is saturated, boron and silica will leak. . The stop time (lifetime) of the mixed bed type ion exchange apparatus is determined by detecting leaked ion components and detecting saturation of any ion exchange resin. Conventionally, it has been designed so that saturation of an ion exchange resin can be detected by a change in specific resistance as will be described later.
However, in this case, the anion component leaks before the cation component. In particular, boron or silica that leaks first is difficult to remove in the latter stage compared to the cation component, and even if the leakage is small, the latter stage is greatly affected.

  Further, if a trace amount of boron or silica remains in pure water, there is a possibility of seriously affecting the reliability of the final product to be manufactured, such as wiring that has been miniaturized rapidly in recent years. Therefore, by using a combination of a conventional mixed-bed ion exchange device and another water treatment device, boron or silica can be removed, or boron or silica leaking earlier can be detected and mixed-bed ion The stop time (life) of the exchange device has been determined.

  Furthermore, since boron and silica are weak electrolytes, their influence on specific resistance is small and detection by measurement of specific resistance is difficult. As a method for detecting leakage of a trace amount of boron or silica, there are an atomic absorption photometry method, an ICP mass spectrometry method, and the like. Since these samples are collected and analyzed by a predetermined analytical instrument, it takes time to obtain an analysis result. There are also boron meters and silica meters as monitors installed online. These are batch-type and not only require more than 5 minutes to analyze one sample, but also have low accuracy. Thus, it has been difficult to accurately detect leakage of boron and silica. For this reason, it has been necessary to stop the ion exchanger in consideration of a safety factor so that dissolved pure water such as boron and silica is not supplied to the subsequent stage as much as possible.

  In the pure water production apparatus of the present invention, since the ability to remove boron and silica can be particularly improved among the anion components, when the ion exchange resin is saturated, leakage has conventionally started after boron and silica. Sodium ions leak out first. Sodium ion is a strong electrolyte ion, and its concentration in pure water directly affects the specific resistance of pure water. Therefore, leakage of sodium ions can be immediately detected by a simple and widely used device called a specific resistance meter, and a mixed bed ion exchange device can be installed before dissolved pure water such as boron and silica is supplied to the subsequent stage. The ion exchange resin can be exchanged or regenerated.

  Next, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments shown below.

  A pure water production apparatus 10 of the present invention shown in FIG. 1 includes a pretreatment system 1, a reverse osmosis membrane device 2 for treating pretreatment water treated by the pretreatment system 1, and a mixed bed ion exchange device 3. A secondary pure water system 4 and a secondary pure water system for processing primary pure water processed by the primary pure water system 4 are provided.

  As raw water, clean water, well water, industrial water, reclaimed water, etc. in which ionic components such as turbid components, fine particles, organic substances, chlorine ions, sodium ions, and trace amounts of boron are dissolved can be used.

  In the pure water production apparatus 10 of the present invention, the pretreatment system 1 is the same as that conventionally known. Specifically, a heat exchanger that adjusts the temperature of the water to be treated, a microfiltration device, an activated carbon device, or the like can be appropriately selected and arranged.

  A conventionally known water treatment device may be provided between the pretreatment system 1 and the reverse osmosis membrane device 2 according to the configuration of the water treatment device installed in the subsequent stage. Specific examples of such water treatment devices include ion exchange devices such as cation exchange devices, anion exchange devices, and chelate resin devices, activated carbon devices, and ultraviolet irradiation devices.

  A conventionally known device can be used as the reverse osmosis membrane device 2. Typical examples of the reverse osmosis membrane device include a device using a cellulose acetate-based or polyamide-based asymmetric membrane or a composite membrane having a polyamide-based active layer. Examples of the membrane structure include asymmetric membranes and composite membranes. Examples of membrane forms include flat membranes, hollow fiber membranes, and spiral membranes.

  The permeated water treated by the reverse osmosis membrane device 2 contains an anionic component as much as 2 to 10 times in terms of gram equivalent of a cation component, and has a specific resistance of 0.1 to 10 MΩ · cm.

  The mixed bed type ion exchange apparatus 3 used in the present invention removes various ion components in permeated water containing a cation component and an anion component at the above-mentioned ratio, and is used in containers such as tanks and cylinders made of vinyl chloride resin. The basic cation exchange resin and the strongly basic anion exchange resin are in the range of 1 / 1.5-1 / 5, preferably 1 / 2.5 in terms of the exchange capacity ratio represented by strongly acidic cation exchange resin / strongly basic anion exchange resin. 1/3. 5 is mixed and filled.

  By setting the mixing ratio calculated by the exchange capacity of the strongly acidic cation exchange resin and the strongly basic anion exchange resin in the mixed bed type ion exchange device 3 within the above range, the amount of carbon dioxide is relatively large, and the anion component is converted to a cation. Even if the permeated water of the reverse osmosis membrane device containing 2 to 10 times the component (in terms of gram equivalent) is passed, the quality of the treated water obtained can be improved. If the mixing ratio calculated by the exchange capacity exceeds 1 / 1.5, the anion component may not be sufficiently removed. Further, when the mixing ratio calculated by the exchange capacity is less than 1/5, the leakage of the cation component occurs earlier than the leakage of the anion component, and as a result, the life of the mixed bed type ion exchange resin as a whole is shortened. There is a risk of increasing the frequency of replacement and playback.

The mixing ratio calculated by the exchange capacity of each ion exchange resin in the mixed bed ion exchange apparatus 3 can be determined by the ion concentration ratio of the water to be treated. Specifically, as a first method, the quality of the permeated water is predicted from the performance of the reverse osmosis membrane device 2, and the gram equivalent of the anion component and the gram equivalent of the cation component are calculated from the water quality, and each ion to be mixed is calculated. There is a method of determining the mixing ratio calculated by the exchange capacity in consideration of the exchange capacity of the exchange resin. That is, the reverse osmosis membrane device 2 can predict the amount of fine particles and ion components that can be removed depending on the properties of the membrane used, etc., so the water quality of the permeated water is predicted and exchanged in consideration of the exchange capacity of each ion exchange resin. The mixing ratio calculated by the volume is determined.
As a second method, the gram equivalent of the anion component and the gram equivalent of the cation component in the permeate obtained by actually analyzing the quality of the permeate of the reverse osmosis membrane device 2 and the exchange capacity of each ion exchange resin are taken into consideration. There is a method of determining the mixing ratio calculated by the exchange capacity.
As a third method, a deionized water apparatus is formed by a mixed bed type ion exchange apparatus 3 in which each ion exchange resin is mixed and filled at an arbitrary mixing ratio within the range of the mixing ratio calculated by the exchange capacity of the present invention described above. There are ways to configure.

  In the mixed bed type ion exchange apparatus, an error may occur between the quality of the treated water actually obtained and the quality of the treated water calculated from the exchange capacity and the amount of water flow. Accordingly, the first to third methods are appropriately selected and changed according to the design conditions of the mixed bed type ion exchange apparatus, the design conditions of the entire pure water production apparatus, the quality of the treated water, the quality of the pure water to be produced, and the like. can do.

As the strongly acidic cation exchange resin, one having an exchange capacity of preferably 1.5 to 2.5 meq / mL, more preferably 2 to 2.5 meq / mL can be used. Moreover, since the hydrolysis of the ion exchange resin is small and the elution of the organic anion component into the ultrapure water is small, a styrene resin having a sulfonic acid group as a functional group is preferable.
The strongly acidic cation exchange resin is preferably H-type because sodium ions having low ion selectivity can be removed. Examples of the method for converting the salt-type cation exchange resin into the H-type include a method in which the salt-type cation exchange resin is treated with an aqueous hydrochloric acid solution or an aqueous sulfuric acid solution and then washed with deionized water. As the H-type conversion rate, 99.95% or more is preferably used.

As the strongly basic anion exchange resin, those having an exchange capacity of preferably 0.7 to 1.5 meq / mL, more preferably 1 to 1.5 meq / mL can be used. In addition, since the ion exchange resin is less hydrolyzed and the organic cation component is less eluted into the ultrapure water, a styrene resin having a quaternary ammonium group as a functional group is preferably used.
The strong base anion exchange resin is preferably an OH type capable of removing fluoride ions having low ion selectivity in consideration of the mixing of fluoride ions in the water to be treated. Examples of the method for converting the Cl-type anion exchange resin into an OH type include a method of treating the Cl-type anion exchange resin with an aqueous sodium hydroxide solution and then washing with deionized water. As the OH-type conversion rate, 99.95% or more is preferably used.

The water flow rate is appropriately determined according to the ion concentration in the water to be treated, the exchange capacity of each ion exchange resin to be mixed, the quality of the pure water produced, the size of the mixed bed ion exchange device, and the like. be able to.
In mixed-bed ion-exchange apparatus 3 used in the present invention, the space velocity SV of water passing through, it is particularly preferable is preferably 10～60H ^-1, a further 30~40h ^-1. If the water flow rate is too fast than the above upper limit value, the ionic component may not be sufficiently removed. On the other hand, when it is slower than the above lower limit value, the quality of primary pure water may be deteriorated by the eluate from the ion exchange resin.

  In the present invention, the temperature of the water to be treated is not particularly limited, but is preferably 5 to 40 ° C. In order to stabilize the quality of the treated water, it is preferable to keep the temperature of the treated water constant. Therefore, it is preferable to provide a plate type heat exchanger etc. in the front | former stage of a reverse osmosis membrane apparatus.

  Since the mixed bed type ion exchange device 3 used in the present invention mixes each ion exchange resin at the above-mentioned ratio, while preventing early leakage of silica, boron, etc., and obtaining higher quality primary pure water, The configuration of the secondary pure water system 5 in the subsequent stage can be simplified.

In the pure water production apparatus 10 of the present invention, the mixed bed type ion exchange device 3 is a chemical regeneration type or a non-regeneration type, and when the treatment flow rate is approximately 10 m ³ / hour or more, the regenerative type mixed bed ion exchange is performed. It is preferable to use an apparatus, and in the case of approximately 20 m ³ / hour or less, it is preferable to use a non-regenerative type. When the processing flow rate is approximately 10 to 20 m ³ / hour, any of them may be used.

In the pure water production apparatus 10 of the present invention, a two-stage reverse osmosis membrane apparatus comprising a series of two-stage reverse osmosis membrane apparatuses may be used instead of the reverse osmosis membrane apparatus 2. In the two-stage reverse osmosis membrane device, the permeated water of the first reverse osmosis membrane device is processed by the subsequent second reverse osmosis membrane device so that the permeated water of the second reverse osmosis membrane device has a high purity. It is a configured device. In the previous stage of the reverse osmosis membrane device 2, the pH may be adjusted to be acidic to prevent scale.
Even in the case of using a two-stage reverse osmosis membrane device, the concentration ratio of the cation component and the anion component of the treated water is the same as described above, so the exchange capacity ratio of the cation exchange resin and the anion exchange resin is 1 / 1.5-1. / 5 is preferable.

The pure water production apparatus 10 of the present invention may include a deaeration device before the reverse osmosis membrane device 2.
By providing a deaeration device, high-quality pure water can be produced. As a deaeration device, a gas-liquid contact type deaeration device, a membrane deaeration device combining a hydrophobic membrane and a vacuum pump, or the like can be used as long as the effects of the present invention are not impaired.
The pure water production apparatus 10 of the present invention may include a two-bed, three-column apparatus equipped with a cation exchange device, a deaeration device, and an anion exchange device in the preceding stage of the reverse osmosis membrane device 2. By providing the two-bed three-column apparatus, it is possible to suppress problems such as clogging of the reverse osmosis membrane due to a minute amount of turbidity remaining in the treated water (pretreated water) of the pretreated water system.

  In the pure water production apparatus 10 of the present invention, a specific resistance meter 6 is installed immediately after the mixed bed ion exchange apparatus 3 to detect a decrease in specific resistance due to leakage of sodium ions, and the specific resistance becomes a predetermined value. When it becomes, the mixed bed type ion exchange apparatus 3 can be stopped. The stop time of the ion exchange device 3 can be determined by measuring the specific resistance, and the stopped ion exchange device 3 can be replaced or regenerated.

  As the specific resistance meter 6, a device that is not easily affected by the ambient temperature change and can measure the specific resistance of pure water up to about 18.2 MΩ · cm, for example, HE-960RW manufactured by HORIBA Co., Ltd. can be used. . When the cation exchange resin is saturated, the specific resistance of the treated water drops rapidly from about 18.0 MΩ · cm. As described above, sodium ions are relatively easy to remove in the subsequent stage. Therefore, depending on the water quality required for the pure water to be produced and the configuration of the water treatment apparatus installed in the subsequent stage, the mixed bed ion exchange apparatus 3 is used. When the specific resistance of pure water at the outlet of the water drops to a desired value, the mixed bed ion exchanger can be stopped. For example, after starting the operation of the pure water production apparatus, the specific resistance of the primary pure water produced drops from a stable state to 17.0 MΩ · cm or more, preferably 17.5 MΩ · cm or more, to less than 17.0 MΩ · cm. At that time, it is preferable to stop the mixed-bed ion exchange device 3 and perform the regeneration process.

When high water quality is required, an arbitrary point in time when the specific resistance falls is determined according to the design of other water treatment equipment that is arbitrarily installed in the primary pure water system. It is also possible to stop the mixed-bed ion exchange device 3 and perform the regeneration process. In this case, in order to produce high-quality pure water, it is preferable to stop the mixed bed ion exchange apparatus 3 at a specific resistance of 10.0 Ω · cm or more. Moreover, it is preferable to stop the mixed bed type ion exchange apparatus 3 by automatic control or by manual operation, and after stopping, it is preferable to perform exchange or regeneration treatment in terms of obtaining high-quality pure water.
It is also possible to determine the cycle according to the time when leakage of an arbitrary ion component starts, calculated from the amount of ion exchange resin to be filled, and similarly stop the mixed bed type ion exchange apparatus and perform exchange or regeneration treatment. .

  In the present invention, the primary pure water which is the treated water of the mixed bed type ion exchange apparatus 3 has a specific resistance of 17.0 MΩ · cm or more and is stable, and the boron concentration is 5 ppb or less and the silica concentration is 5 ppb or less, more preferably. Has a boron concentration of 1 ppb or less, a silica concentration of 2 ppb or less, and a specific resistance of 17.0 MΩ · cm or more, more preferably 18.0 MΩ · cm or more.

Primary pure water which is treated water of the mixed bed type ion exchange device 3 can be used as it is as water for medical, pharmaceutical manufacturing, semiconductor manufacturing device cooling water or the like. In order to obtain ultrapure water with a higher specific resistance of 18.0 MΩ · cm or more, such as water for cleaning silicon wafers, a secondary pure water system 5 is installed at the subsequent stage of the mixed bed type ion exchanger 3. Secondary pure water can be further purified.
In this case, since the primary pure water has the above-described high specific resistance by removing ion components such as sodium and chlorine ions by the mixed bed ion exchange device 3, the configuration of the secondary pure water system 5 is simplified. Can do.

  The secondary pure water system 5 described above is also referred to as a subsystem, and a conventionally known one can be used. Specifically, an ultraviolet irradiation device, a polisher, an ultrafiltration device, a membrane deaeration device, and the like can be appropriately selected and arranged.

Next, an Example is shown and this invention is demonstrated in detail. Examples 1 to 5 are examples, and examples 6 and 7 are comparative examples.
The apparatus and conditions used in the examples are as follows.

Activated carbon device: NCC-200AC (manufactured by Nomura Micro Science Co., Ltd.)
Reverse osmosis membrane device 2: SU-710 (manufactured by Toray Industries, Inc.)
Mixed bed type ion exchanger 3: made of vinyl chloride resin, inner diameter φ50mm
Strong acid cation exchange resin (C): Duolite C20 (manufactured by Dow Chemical Co., Ltd.)
Strongly basic anion exchange resin (A): Duolite A113 (manufactured by Dow Chemical Co., Ltd.)
Specific resistance meter 6: HE-960RW (manufactured by HORIBA)
Raw water: Well (electric conductivity: 224 μS / m (0.0044 MΩ · cm), TOC: 1 mg / L)
Flow rate: 0.6L / min

[Example 1]
The permeated water (specific resistance 0.1 MΩ · cm, cation concentration 880 ppb, anion concentration 1765 ppb) treated with the activated carbon device and then with the reverse osmosis membrane device 2 was added to 0.25 L of strongly acidic cation exchange resin. And 0.65 L of strong basic anion exchange resin (C / A = 1 / 1.4 in terms of exchange capacity ratio) were mixed, and water was passed through the mixed bed type ion exchange device 3.
The quality of the permeated water is shown in Table 1.

[Example 2]
In the mixed bed type ion exchanger 3, 0.17L of strong acidic cation exchange resin and 0.73L of strong basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 2.2) were mixed and filled. The conditions were the same as in Example 1 except for the above.
[Example 3]
The mixed bed type ion exchanger 3 was mixed and filled with 0.12 L of strongly acidic cation exchange resin and 0.78 L of strong basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 3.2). The conditions were the same as in Example 1 except for the above.
[Example 4]
The mixed bed type ion exchanger 3 was filled with 0.09 L of strong acidic cation exchange resin and 0.91 L of strong basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 4.6). The conditions were the same as in Example 1 except for the above.
[Example 5]
In the mixed bed type ion exchanger 3, 0.08L of strongly acidic cation exchange resin and 0.82L of strongly basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 5.0) were mixed and filled. The conditions were the same as in Example 1 except for the above.
[Example 6]
In the mixed bed type ion exchanger 3, 0.3 L of strong acidic cation exchange resin and 0.6 L of strong basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 1.0) were mixed and filled. The conditions were the same as in Example 1 except for the above.
[Example 7]
In the mixed bed type ion exchanger 3, 0.07L of strongly acidic cation exchange resin and 0.83L of strongly basic anion exchange resin (exchange capacity ratio C / A = 1.0 / 5.6) were mixed and filled. The conditions were the same as in Example 1 except for the above.

About Examples 1-6, the specific resistance meter is installed in the exit of the mixed bed type ion exchange apparatus 3, the water flow time until the specific resistance becomes 17.5 MΩ · cm or less, and the mixed bed type ion exchange apparatus at that time The concentration of silica, boron and sodium ions in the primary pure water at the outlet 3 was measured.
The results are shown in Table 2.

  As shown in Table 2, it can be seen that the pure water producing apparatuses of Examples 1 to 5 have a long time until the specific resistance becomes 17.5 MΩ · cm or less, and Example 3 has the longest time. Furthermore, it can be seen that sodium leaks first when the specific resistance is 17.5 MΩ · cm or less. In Example 7, the specific resistance reached 17.0 MΩ · cm and was not stabilized, so analysis was not performed.

Furthermore, about Examples 1-6, the total water flow amount until specific resistance became 17.5 Mohm * cm was measured. Fig. 2 shows the relationship between the exchange capacity ratio of the cation exchange resin and the anion exchange resin and the value obtained by dividing the total water flow rate (L) by the resin amount (L) (the amount of treated water per 1 L of mixed bed type ion exchange resin). Show.
From FIG. 2, when the cation exchange resin and the anion exchange resin have an exchange capacity ratio of 1 / 3.2 (Example 3), the process per unit resin amount until the ion component leaks from the mixed bed type ion exchange resin. It turns out that the amount of water becomes the maximum.

3, 4, and 5 show the relationship between the time from the start of water flow and the specific resistance in the primary pure water collected at the outlet of the mixed bed ion exchanger in Examples 3, 6 and 7, respectively. Show.
FIG. 3 shows that the pure water production apparatus of the present invention can produce pure water having a sufficient specific resistance even after 200 hours have passed since the start of water flow.
From FIG. 4, in Example 6, the specific resistance of the obtained primary pure water is decreased after about 100 hours have elapsed since the start of water flow, that is, leakage of ion components from the ion exchange resin. I understand. From FIG. 5, it can be seen that in Example 7, the specific resistance of the pure water obtained is less than 17.0 MΩ · cm, and the required water quality cannot be obtained without satisfying the function as the mixed bed type ion exchanger.

DESCRIPTION OF SYMBOLS 10 ... Pure water manufacturing apparatus, 1 ... Pretreatment system, 2 ... Reverse osmosis membrane apparatus, 3 ... Mixed bed type ion exchange apparatus, 4 ... Primary pure water system, 5 ... Secondary pure water system, 6 ... Resistivity meter .

Claims (8)

In a pure water production apparatus comprising a pretreatment system and a primary pure water system,
The primary pure water system includes a reverse osmosis membrane device, and a mixed bed ion exchange device installed immediately after the reverse osmosis membrane device,
In the mixed bed type ion exchange apparatus, a strongly acidic cation exchange resin and a strongly basic anion exchange resin are converted into a ratio of 1 / 1.5-1.5 by an exchange capacity ratio represented by the strongly acidic cation exchange resin / the strongly basic anion exchange resin. A pure water production apparatus characterized by being mixed and filled as 1/5.   The mixed bed type ion exchange apparatus comprises a strongly acidic cation exchange resin and a strongly basic anion exchange resin in an exchange capacity ratio of 1 / 2.5-2.5 as represented by the strongly acidic cation exchange resin / the strongly basic anion exchange resin. The pure water manufacturing apparatus according to claim 1, wherein the water is mixed and filled as 1 / 3.5.   3. The pure water production apparatus according to claim 1, wherein the reverse osmosis membrane device is a two-stage reverse osmosis membrane device.   The pure water production apparatus according to any one of claims 1 to 3, wherein a specific resistance of water to be treated which is passed through the mixed bed ion exchange apparatus is 0.1 to 10 MΩ · cm.   5. The pure water production apparatus according to claim 1, further comprising a two-bed / three-column apparatus between the pretreatment system and the reverse osmosis membrane apparatus.   The pure water production apparatus according to claim 1, further comprising a deaeration device upstream of the reverse osmosis membrane device.   A specific resistance meter is provided in the subsequent stage of the mixed bed type ion exchange device so that water flow to the mixed bed type ion exchange device is stopped at any time when the specific resistance drops and becomes less than 17.0 MΩ · cm. It is controlled, The pure water manufacturing apparatus of any one of Claim 1 thru | or 6 characterized by the above-mentioned.   8. The secondary pure water system for further purifying the treated water in the primary pure water system at a subsequent stage of the primary pure water system, according to claim 1. Pure water production equipment.

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