JPH0824852A - Pure water or ultrapure water making apparatus - Google Patents

Abstract

PURPOSE:To always stably obtain an ultrapure water low in silica concn. without increasing the replacing frequency of an ion exchanger by determining the replacing period of two or more aion exchange columns connected in series by monitoring silica concn. CONSTITUTION:The ultrapure water making apparatus has cartridge polishers 8a, 8b being mixed bed ion exchange columns connected in series and ions in a pure water nearly an ultrapure water are further removed herein. The water coming out from the respective cartridge polishers 8a, 8b is supplied to an ultrafiltration membrane device 9 to remove fine particles and the filtered water is supplied to a use place. In this case, a silica meter 20 monitoring the silica concn. of the front stage polisher 8a(or 8b) is provided and at each time when the detected silica concn. reaches a predetermined value, the front stage polisher is regenerated to be arranged to a rear stage. Or, the front stage polisher is removed and respective valves V1-V12 are changed over and controlled in order to connect a new polisher to the rear stage of the rear stage polisher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing pure water or ultrapure water. More specifically, it is used in the electronic industry or the like, and is used for pure water or ultrapure water with a reliably reduced silica concentration. Manufacturing equipment

[0002]

2. Description of the Related Art A conventional apparatus for producing ultrapure water has a structure shown in the flow chart of FIG. FIG.
Medium 1 is a pretreatment device, which removes a part of suspended substances and organic substances in raw water such as industrial water, city water, well water, and groundwater to obtain pretreatment water. The pretreated water is obtained by, for example, connecting a cation exchange column filled with a cation exchange resin, a decarboxylation column, and an anion exchange column filled with an anion exchange resin in this order. It is sent to a desalting apparatus such as the two-bed, three-tower type desalting apparatus 2, which removes impurity ions in the treated water.

A reverse osmosis membrane (RO) device 3 is equipped with a reverse osmosis membrane. The reverse osmosis membrane device 3 removes a trace amount of impurities such as inorganic ions, organic substances and fine particles remaining in the treated water.

Reference numeral 4 is a vacuum degassing apparatus, which removes dissolved oxygen in the reverse osmosis membrane apparatus treated water. Reference numeral 5 is a mixed bed type desalting device filled with a mixed resin of a cation exchange resin and an anion exchange resin, in which residual ions are further removed to produce high-purity pure water, which is the primary pure water tank. 6 is supplied. The pretreatment device 1 to the primary pure water tank 6 is usually called a primary pure water device.

An ultraviolet oxidizer 7 irradiates the pure water supplied from the primary pure water tank 6 with ultraviolet rays to oxidize and decompose organic substances in the pure water and sterilize bacteria. Reference numerals 8a and 8b denote cartridge polishers, which are mixed bed type ion exchange towers connected in series, in which impurities in the pure water, which are almost free of impurities, are further removed. Cartridge polisher 8
The water exiting a and 8b is treated by an ultrafiltration membrane device 9 equipped with an ultrafiltration membrane (UF) to remove fine particles and the like to produce ultrapure water, and then to the place of use 10. The residual ultrapure water is supplied to the primary pure water tank 6 while part of it is supplied if necessary. The devices after the primary pure water tank 6 are usually called secondary pure water devices or subsystems.

This apparatus for producing ultrapure water is operated while replacing the cartridge polishers 8a and 8b connected in series at predetermined intervals. The replacement of the cartridge polishers 8a and 8b is performed when the resistivity of the treated water of the preceding cartridge polisher (8a in FIG. 4) becomes lower than the specified value or the amount of water taken reaches the specified amount, then the cartridge polisher of the latter stage is replaced. (8b in FIG. 4) is the former stage, and the latter stage is a so-called merry-go-round system in which a cartridge polisher containing a new mixed ion-exchange resin previously regenerated in another place is newly connected and water is passed. . This will be described in more detail with reference to FIG.

In FIG. 5, the current state of each valve is V1-
Open, V2-Closed, V3-Open, V4-Open, V5-Closed, V6-
Open, V7-Open, V8-Closed, V9-Open, V10-Open, V1
1-closed and V12-opened, the primary pure water supplied from the primary pure water tank 6 is, as shown by the thick line in FIG. 5, an ultraviolet oxidation device 7 → cartridge polisher 8a → cartridge polisher 8b → ultrafiltration membrane. Water is passed through the device 9 in this order. Now, the resistivity meter 11 is installed between the front-stage cartridge polisher 8a and the rear-stage cartridge polisher 8b, and the treated water quality of the front-stage cartridge polisher 8a is constantly monitored by this. The measured value by the resistivity meter 11 is a predetermined value, for example, 17.5 MΩ.
When it is less than cm, cartridge polisher 8a
Is judged to have reached the end of its life, and the state of each valve is set to V1-close,
V2-open, V3-open, V4-close, V5-close, V6-open,
V7-open, V8-closed, V9-closed, V10-closed, V11-
As shown in FIG. 6, the used cartridge polisher 8a is removed by closing and V12-closing, and during that time, the primary pure water supplied from the primary pure tank 6 is only the cartridge polisher 8b as shown by the bold line in FIG. Is processed in.

Next, as shown in FIG. 7, after a new cartridge polisher 8c is attached in place of the removed cartridge polisher 8a, the cartridge polisher 8b is in the front stage and a new cartridge polisher 8c.
Each valve is switched so that is in the latter stage, and water flow is started. Each valve shown in FIG. 7 has V1-closed, V2-opened, V3
-Open, V4-Closed, V5-Open, V6-Open, V7-Closed, V8
-Open, V9-open, V10-closed, 11-open, V12-open, and the primary pure water passes through the ultraviolet oxidation device 7-> cartridge polisher 8b-> cartridge polisher 8c-> ultrafiltration membrane device 9 in that order. To be done.

However, when the cartridge polisher is replaced by the so-called merry-go-round method by monitoring the resistivity in this way, a considerable amount of silica has already leaked into the treated water of the cartridge polisher in the subsequent stage at the time of replacement, It was found that the concentration of silica in the ultrapure water, which is the treated water, is quite high. FIG. 8 shows changes in silica concentration in ultrapure water at the place of use 10. FIG. 8 shows a cartridge polisher as an H-type strongly acidic cation exchange resin, Amberlite (registered trademark, the same applies hereinafter) IR-124, and an OH type strongly basic anion exchange resin, which have been sufficiently regenerated in other places. The data is obtained when a mixed ion-exchange resin having a matrix of Amberlite IRA-402BL, which is a styrene-divinylbenzene resin, is mixed at a volume ratio of 1: 2 is used. Furthermore, when the decrease in the resistivity of the cartridge polisher treated water in the previous stage is detected and the polisher that has reached the end of its life is replaced,
As shown in Table 1, the silica concentration in the ultrapure water becomes extremely high in the process (process shown in FIG. 6) of treating the treated water of the ultraviolet oxidation device 7 with the polisher alone installed in the subsequent stage. Also became clear.

[0010]

[Table 1] In such a conventional so-called merry-go-round method, the reason why silica leaks from the latter cartridge polisher much earlier than expected from the resistivity measurement results is not clear, but the former cartridge polisher has a higher resistivity. When it is used until the decrease in the cartridge is detected, silica with weak anion and weak adsorption power to the anion exchange resin has already leaked from the cartridge polisher in the previous stage and is adsorbed in the cartridge polisher in the subsequent stage. When water is collected by recombining with the cartridge polisher, the adsorbed silica is replaced with carbonic acid or organic acid in the oxidation-treated water produced by the UV-oxidation treatment in the previous stage, especially when the UV-oxidizer is connected in the preceding stage of the cartridge polisher. Is extruded,
As a result, a large amount of these ions were loaded on the cartridge polisher in the latter stage from the initial stage of water sampling after the exchange, and since silica is an extremely weak acid, these ions adsorbed on the anion exchange resin of the former polisher were Ions are gradually eluted by hydrolysis by passing pure water,
It is presumed that the load is applied to the polisher in the subsequent stage.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to produce pure water or ultrapure water capable of constantly maintaining a low silica concentration. Another object of the present invention is to provide an apparatus, and further, to provide an apparatus for producing pure water or ultrapure water capable of constantly maintaining a low silica concentration without increasing the exchange frequency of the ion exchange apparatus.

[0012]

In order to achieve the above object, the present invention provides an ion exchange apparatus comprising a plurality of ion exchange columns connected at least in series filled with anion exchange resin, and the ion exchange apparatus. A production apparatus for pure water or ultrapure water having a silica meter for monitoring the silica concentration in the treated water of the foremost ion exchange tower, wherein the ion exchange apparatus is for treating the treated water in the foremost ion exchange tower. Each time the silica concentration reaches a specified value, the frontmost ion exchange column is regenerated and placed in the last stage, or the frontmost ion exchange column is removed and an ion exchange resin is placed after the last ion exchange column. An apparatus for producing pure water or ultrapure water, characterized by being a method of connecting a regenerated new ion exchange tower, wherein the ion exchange apparatus is a single bed anion exchange apparatus, At least a portion of the resin matrix of the ion exchange resin filled in comprises that the anion exchange resin of an acrylic acid-based. Hereinafter, the present invention will be described in detail.

As the ion exchange device, the membrane separation device, the silica analyzer, and other devices and equipment that compose the pure water or ultrapure water production device of the present invention, those known per se can be used as they are. Further, the basic configurations of the conventional pure water producing apparatus and ultrapure water producing apparatus are basically applied to the present invention as they are.

Any silica meter may be used as long as it can measure a minute amount of silica in pure water or ultrapure water, and examples thereof include Ion Chromatograph DX-300 manufactured by Dionex.

In the present invention, the concentration of silica in the treated water of the ion exchange device is measured and monitored, and when the silica concentration exceeds a predetermined value, the ion exchange column is exchanged. It is preferable to determine it according to the purpose based on the upper limit of the silica concentration of the required pure water or ultrapure water.

The ion exchange apparatus used in the present invention may be of any type as long as it uses an ion exchange column packed with an anion exchange resin capable of adsorbing at least silica, for example, a strong acid cation exchange resin and a strong basicity. Two of the mixed-bed type ion-exchange columns filled with the mixed resin with the anion-exchange resin connected in series, and the single-bed type anion-exchange column obtained by filling the strong basic anion-exchange resin alone. One in which one or more towers are connected in series, or a single bed type ion exchange device, in which a strongly basic anion exchange resin and a weakly basic anion exchange resin are stacked and packed in the same tower. A so-called multi-layer bed type anion exchange tower in which two or more towers are connected in series can be used.

Further, as the above-mentioned ion exchange tower, for example, when the silica concentration in the treated water of the ion exchange tower reaches a predetermined value, a new ion exchange filled with a regenerated ion exchange resin which has been regenerated in another place in advance. The so-called cartridge type ion-exchange tower is used to continue the treatment by exchanging with the tower, or when the silica concentration reaches a predetermined value, the packed ion-exchange resin is regenerated using the attached regeneration equipment for the treatment. Known ones such as a so-called regenerative type ion exchange column which is continued can be used.

When the silica concentration in the treated water of the ion exchange column located at the frontmost stage reaches a predetermined value, the ions regenerated at the rear stage of the last ion exchange column except this frontmost ion exchange column. The actual operation of connecting a new ion exchange column filled with an exchange resin and then passing water to be treated in order from the ion exchange column which was connected to the second stage up to now is shown in FIGS. This can be easily done by switching the piping and valves as shown.

The type of anion exchange resin used in the present invention is not particularly limited as long as it can adsorb silica, that is, a strongly basic anion exchange resin, but it is usually used for pure water or ultrapure water production. The strongly basic anion exchange resin whose resin base is an acrylic resin is more effective than the strongly basic anion exchange resin whose base resin is styrene-divinylbenzene (St-DVB). As shown in the examples, it is preferable in that it has a large silica removing ability.

In the case of the device of the present invention, the exchange time of the frontmost ion exchange column is determined based on the silica concentration. Therefore, as is clear from the graph of FIG. 8, the exchange time is based on the resistivity. The life of the ion exchange column is shortened as compared with the conventional method of judging. Therefore, it is advantageous to use an acrylic acid-based anion exchange resin as the resin matrix having a large silica removal ability, in that the frequency of exchange or regeneracy in the ion exchange column is reduced. Further, an acrylic acid-based anion exchange resin may be mixed with the styrene-divinylbenzene-based anion exchange resin, for example.

As the acrylic acid type anion exchange resin, for example, Amberlite IRA-458, I
RA-958 etc. are mentioned.

[0022]

The present invention will be described below in detail with reference to examples.

Embodiment 1 FIG. 1 shows a partial configuration of an embodiment of the ultrapure water production system of the present invention. In this example, only the constituent parts of the cartridge polishers 8a and 8b of the ultrapure water production system shown in FIG. 4 are configured to have a silica meter 20 as shown in FIG. When the silica concentration at the outlet of the cartridge polisher 8a at the preceding stage becomes, for example, 15 ng / L or more, the cartridge replacement work is performed.

According to such an operation method, since silica is not accumulated in the cartridge polisher 8b in the subsequent stage, it is possible to always stably prevent silica from leaking out.

In this embodiment, two cartridge polishers are used by being connected in series as the ion exchange tower, but the present invention is not limited to this, and three or more cartridge polishers may be connected in series. Is.

Embodiment 2 FIG. 2 shows another embodiment of the ultrapure water production system of the present invention. In the ultrapure water production system of FIG. 2, an ultraviolet oxidation device 40 is installed between the reverse osmosis membrane device 3 and the vacuum degassing device 4 in the ultrapure water production system of FIG. Anion exchange resin (AER) single bed type ion exchange towers 60a, 6 instead of
0b is installed, and as shown in FIG.
It is configured to include 0 and is operated by a so-called merry-go-round system. In FIG. 2, in the water treated by the reverse osmosis membrane device 3, TOC dissolved therein is first decomposed into an organic acid or carbonic acid by the ultraviolet oxidation device 40, and subsequently dissolved oxygen and dissolved by the vacuum degassing device 4. Some of the carbon dioxide that is being removed is removed. Next, the AER single-bed ion exchange towers 60a and 60b remove anions contained in a small amount. AER single bed type ion exchange tower 60a, 60
Reference numeral b is a regenerative ion exchange tower. After the water collection process is completed, the former ion exchange tower is regenerated by the attached regenerator and then installed in the latter stage of the ion exchange tower that was previously located in the latter stage. Enter the water sampling process. The treated water in the AER single-bed ion exchange towers 60a and 60b is sent to the primary pure water tank 6. After the ultraviolet oxidation device 7, the cartridge polishers 8a and 8b are provided with the silica meter 20 interposed in the configuration shown in FIG. 1 and operated by a so-called merry-go-round method. Further, ultrapure water is supplied to the place of use 10 through the ultrafiltration membrane device 9.

In the above embodiment, the present invention was applied to both of the AER single bed type ion exchange towers 60a and 60b and the cartridge polishers 8a and 8b, but the present invention was applied to either one. May be. AE
When the present invention is applied to the R single-bed type ion exchange towers 60a and 60b, as shown in FIG. In FIG. 3, 70 is an ultraviolet sterilizer and 80 is a mixed bed type cartridge polisher.

Example 3 In Examples 1 and 2, the completion of water sampling in the former ion exchange column of the so-called merry-go-round system was used as the silica concentration standard. Therefore, the frequency of resin exchange or regeneration of the ion exchange column increases. Is as described above. In this example, the difference in the water sampling period depending on the type of anion exchange resin packed in the ion exchange column is shown.

Table 2 shows the AER single-bed ion exchange column 60a of the ultrapure water producing apparatus having the structure shown in FIG. 2 and two types of strongly basic anion exchange resins having different resin bases as shown in Table 2. The difference in the sampling period (the period during which the treated water reaches the standard value) due to the difference in the sampling standard when used is that the resin matrix is styrene-divinylbenzene (St-DVB).
It is a comparison when the water sampling period in the case of resistivity reference in Amberlite IRA-402BL is 100.

The water flow rate was SV50 per tower.

[0031]

[Table 2] As is clear from Table 2, when the sampling stop condition of the former ion exchange column is based on silica, the comparative value of the sampling period when using Amberlite IRA-402BL which is an anion exchange resin of St-DVB system is While it is 78%,
Amberlite IRA-458 which is acrylic acid resin
The water collection period was 87%, and the life extension effect of about 10% was obtained when the acrylic acid anion exchange resin was used. Acrylic acid type anion exchange resin IRA-
The reason for such a life prolonging effect when 458 is used is not clear, but it is considered that it has a higher basicity than the conventional styrene-divinylbenzene anion exchange resin, probably because it is an acrylic acid matrix resin. It is conceivable that the affinity with silica, which exists as a weak acid, is stronger.

Further, as can be seen from Table 2, in both resins A and B, the water sampling period based on the silica is shorter than the water sampling period based on the resistivity. Therefore, in the so-called merry-go-round method, when the merry-go-round operation was performed based on the resistivity standard, the silica had already leaked beyond the standard value at the time when the water sampling end point was reached, and the conventional resistivity standard was used. It is clear that driving should be avoided.

[0033]

In the present invention, the exchange time of two or more ion exchange columns connected in series is determined by monitoring the silica concentration, so that ultrapure water with a low silica concentration is always stable. Obtainable.

[Brief description of drawings]

FIG. 1 is a partial flow path configuration diagram showing an example of a flow path configuration of an ion exchange apparatus of an ultrapure water production apparatus of the present invention.

FIG. 2 is a flow chart showing an embodiment of the present invention.

FIG. 3 is a partial flowchart showing another embodiment of the present invention.

FIG. 4 is a flowchart showing a configuration example of a conventional ultrapure water production apparatus.

FIG. 5 is a flow explanatory diagram showing a state before replacement of the cartridge polisher.

FIG. 6 is a flow explanatory diagram showing a state during replacement of the cartridge polisher.

FIG. 7 is a flowchart illustrating a state after the cartridge polisher is replaced.

FIG. 8 is a graph showing the relationship between the water passage period of a conventional cartridge polisher and the silica concentration in the treated water of the polisher.

[Explanation of symbols]

 1 Pretreatment Device 2 2 Bed 3 Tower Desalination Device 3 Reverse Osmosis Membrane Device 4 Vacuum Degassing Device 5 Mixed Bed Desalination Device 6 Primary Pure Water Tank 7 UV Oxidation Device 8a, 8b Cartridge Polisher 9 Ultrafiltration Membrane Device 10 Place of use 11 Resistivity meter 20 Silica meter 70 UV sterilizer 80 Cartridge polisher

Claims (3)

[Claims] 1. An ion exchange apparatus comprising a plurality of ion exchange towers connected in series and at least filled with an anion exchange resin, and a silica concentration in treated water of an ion exchange tower at the frontmost stage of the ion exchange apparatus is monitored. An apparatus for producing pure water or ultrapure water having a silica meter, wherein the ion-exchange device is provided at the frontmost stage every time when the concentration of silica in the treated water of the first-stage ion-exchange column reaches a predetermined value. Is placed at the last stage, or the ion exchange column at the frontmost stage is removed, and a new ion exchange column made up of regenerated ion exchange resin is connected to the latter stage of the ion exchange column at the last stage. An apparatus for producing pure water or ultrapure water characterized by the above. 2. The apparatus for producing pure water or ultrapure water according to claim 1, wherein the ion exchange apparatus is a single bed type anion exchange apparatus. 3. The apparatus for producing pure water or ultrapure water according to claim 1, wherein at least a part of the ion exchange resin filled in the ion exchange apparatus is an anion exchange resin whose resin matrix is acrylic acid. .