KR101563169B1 - Pure water production apparatus and pure water production method - Google Patents

Abstract

The ultrapure water producing apparatus includes an activated carbon device 1, a heater 2, a membrane filtration device 3, a raw water tank 4, a pretreatment device 5, and a pretreatment device 5 in order to efficiently produce pure water having a low boron concentration. And a pretreatment device 5 comprises a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 8, (RO) apparatus 9 and a decalinization membrane apparatus 10. The pretreatment apparatus 5 is configured to treat the treated water W1 having a chloride ion concentration of 100 ppb or less in accordance with the quality of the raw water W0 So that it can be introduced into the desalting chamber of the deionization unit 6.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pure water producing apparatus and a pure water producing method,

The present invention relates to a pure water producing apparatus suitable for assembling an ultrapure water producing system and the like, and more particularly to a pure water producing apparatus for producing pure water having a low boron concentration. The present invention also relates to a pure water producing method suitable for an ultrapure water producing system and the like, and more particularly to a pure water producing method for producing pure water having a low boron concentration.

The ultrapure water producing system generally comprises a pretreatment system, a primary pure water system and a subsystem. The pretreatment system is constituted by a dechlorination apparatus using a coarse filtration, a MFR membrane (microfiltration membrane), a UF membrane (ultrafiltration membrane), and a dechlorination unit with activated carbon.

The primary pure water system is composed of an RO (reverse osmosis membrane) device, a demineralization device, an electric deionization device, etc., and most of the ion components and TOC components are removed. Further, the sub-system is constituted by a UV apparatus (ultraviolet oxidation apparatus), a non-regenerated ion exchange apparatus, a UF apparatus (ultrafiltration apparatus) or the like, and the removal of trace ions, especially the removal of trace microorganisms, . The ultrapure water made in the subsystem is sent to the point of use, and the excess ultrapure water is generally returned to the tank in the front stage of the subsystem.

However, the required water quality of ultrapure water becomes strict every year, and ultrapure water having a boron concentration of 10 ppt or less is required in the cutting-edge electronic industry field. Although the boron exists mostly as boric acid ions in ultrapure water, it is difficult to remove the boric acid ions because they are weak ions. In order to produce pure water having a low boron concentration, it has been proposed to increase the boron removal rate in the RO apparatus by setting the water supply of the RO apparatus at pH 10 or more (see Patent Document 1).

It has also been proposed to bring the treated water after the pretreatment into contact with a boron selective ion exchange resin (see Patent Document 2), desalinate raw water in a desalination apparatus such as an RO apparatus, and then pass it through a boron adsorption resin tower 3).

Further, there has been proposed an ultrapure water producing apparatus in which raw water is contacted with a boron selective ion exchange resin through a pretreatment device, a two-stage RO device, an electric regenerative desalination device, and the like (see Patent Document 4).

Patent Document 1: Japanese Patent No. 3321179

Patent Document 2: Japanese Patent No. 3200301

Patent Document 3: JP-A-8-89956

Patent Document 4: JP-A-9-192661

In the pure water production method described in Patent Document 1, it is necessary to use an alkali or an anion exchange resin tower in order to adjust the water supply of the RO apparatus to pH 10 or more, and it is necessary to carry out continuous operation There is a problem that it can not be done.

In the pure water production methods described in Patent Documents 2 to 4, boron is removed by passing treated water through a boron-selective ion exchange resin or a boron adsorption resin. However, if the boron concentration of the water to be treated is high, The boron concentration in the for-treatment water is low, for example, about 10 ppb or less, which results in a problem that the removal rate is lowered. Further, since there is a risk of elution of TOC from the boron adsorbent resin, cleaning and conditioning of the boron adsorbent resin are also required.

Further, although it is considered that the boric acid ions, which are anions, should be simultaneously removed by the electric deionization apparatus, since the boric acid ions are weak ions, the removal rate is set to 90% or more even when the current density of the electrodeionization apparatus is increased It is difficult. Further, even when the RO apparatus is combined, the boron removal rate can not be made 98% or more.

That is, in recent years, the required water quality of ultrapure water has become strict every year, so that a boron concentration of 100 ppt or less, a boron concentration of 10 ppt or less, and in some cases 1 ppt or less of water quality is required in the cutting- There was no pure manufacturing equipment available. In order to achieve this in the electrodeionization apparatus, it is necessary to set the removal rate of boron in the electrodeionization apparatus to 99% or more, especially 99.5% or more.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a pure water producing apparatus capable of efficiently producing pure water having a low boron concentration. It is another object of the present invention to provide a pure water producing method capable of efficiently producing pure water having a low boron concentration.

In order to solve the above problems, the present invention provides a pure water producing apparatus having a pretreatment device and an electrodeionization device for taking in treated water of the pretreatment device into a desalting chamber for performing a deionization treatment, And a chloride ion concentration of the treated water introduced into the desalting chamber of the electrodeionization apparatus is set to 100 ppb or less (Invention 1).

According to the above invention (invention 1), the chloride ion is easier to remove than boron, and the chloride ion concentration of the treated water introduced into the electrodeionization apparatus is made 100 ppb or less, whereby the removal rate of boron in the electrodeionization apparatus is 99 % Or more.

In the above invention (Invention 1), it is preferable that the pretreatment apparatus has one or two RO membrane elements, and the carbonic acid concentration of the treated water to be introduced into the desalting chamber of the electrodeionization apparatus is preferably 1 ppm or less (invention 2) , The pretreatment apparatus may further include one or more ion exchange resin towers (Invention 3). In such an invention (Invention 3), it is preferable that the pretreatment apparatus further comprises one or more ion- , A decarbonated tower or a vacuum degassing tower (invention 4).

According to the above invention (inventions 2 to 4), it is possible to further reduce the chloride ion concentration and the carbonate ion concentration of the treated water introduced into the desalting chamber of the electrodeionization apparatus, and further improve the removal rate of boron in the electrodeionization apparatus .

In the above inventions (Invention 1 to 4), it is preferable to introduce a part of the desalted water of the electric deionization device into the concentration chamber of the electric deionization device in the direction opposite to the introduction direction of the treated water into the desalting chamber ).

According to the invention (Invention 5), the concentration gradient of boron between the desalting chamber and the concentrating chamber is relaxed by flowing the water (desalted water) of the desalting chamber having good water quality from the outlet side to the inlet side of the desalting chamber to the concentrating chamber The removal rate of boron in the electrodeionization apparatus can be further improved.

In the above inventions (Invention 1 to 5), it is preferable that the above-mentioned electric deionization apparatus is provided in a plurality of stages in series (invention 6). According to the invention (invention 6), since the removal rate of boron can be increased up to 99.99%, ultrapure water having a boron ion concentration of 1 ppt or less can be supplied.

Secondly, the present invention is a method for producing pure water by treating raw water with a pretreatment device and introducing the treated water into a desalting chamber of an electric deionization device, wherein the pretreatment device has a chloride ion concentration of not more than 100 ppb And a treated water is introduced into the desalting chamber of the electrodeionization apparatus (invention 7).

According to the invention (invention 7), the chloride ion is easier to remove than boron, and the chloride ion concentration of the treated water introduced into the electrodeionization apparatus is 100 ppb or less, whereby the removal rate of boron in the electrodeionization apparatus is 99 % Or more.

In the invention (invention 7), it is preferable that a part of the desalted water of the electric deionization device is introduced into the concentration chamber of the electric deionization device in the direction opposite to the introduction direction of the treated water into the desalting chamber.

According to the invention (invention 8), the concentration gradient of boron between the desalting chamber and the concentrating chamber is relaxed by flowing the water (desalted water) from the desalting chamber having good water quality to the concentrating chamber from the outlet side to the inlet side of the desalting chamber The removal rate of boron in the electrodeionization apparatus can be further improved.

In the above invention (inventions 7 and 8), it is preferable that the electrodeionization apparatuses are provided in plural stages in series (invention 9). According to the invention (Invention 9), since the removal rate of boron can be increased up to 99.99%, it becomes possible to supply ultrapure water having a boron ion concentration of 1 ppt or less.

In the above invention (Invention 9), it is preferable to introduce the concentrated water of the remainder of the electrodeionization apparatus of the plurality of electrodeionization apparatuses into the desalination chamber of the first-stage electrodeionization apparatus together with the treatment water Invention 10).

According to the invention (invention 10), since the concentrated water of the last electrodeionization apparatus is not only lower in boron concentration than treated water after treatment in the pretreatment apparatus but also has a considerably low chloride ion concentration, The basic configuration of the apparatus can further improve the boron concentration of the treated water from the desalination chamber of the first stage electrodeionization apparatus in this state.

According to the pure water producing apparatus of the present invention, the chloride ion is easier to remove than boron and the chloride ion concentration of the treated water introduced into the electrodeionization apparatus is 100 ppb or less, whereby the removal rate of boron in the electrodeionization apparatus is 99 % Or more. According to the present invention, since boron can be largely removed by the electric deionization device, continuous operation is possible, and since chemicals such as alkali are not used, the environmental load is small and the boron concentration of the water (raw water) It is possible to cope with a wide area. In addition, since breakage does not occur compared to the boron adsorbent resin and the like, pure water with a low boron concentration can be stably supplied over several years. In addition, by providing a plurality of electric deionization units in series, ultra pure water having a boron ion concentration of 1 ppt or less can be supplied.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a flow chart showing a pure water producing apparatus according to a first embodiment of the present invention. Fig.
2 is a schematic structural view showing a desalting chamber and a concentrating chamber of an electrodeionization apparatus according to a first embodiment of the present invention;
3 is a flow chart showing a pure water producing apparatus according to a second embodiment of the present invention.
4 is a flow chart showing a pure water producing apparatus of Comparative Example 1. Fig.

[First Embodiment]

Hereinafter, a first embodiment of the pure water producing apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a flow chart showing a pure water producing apparatus according to the present embodiment, and FIG. 2 is a schematic diagram showing an electrodeionization apparatus in the present embodiment.

1, the ultrapure water producing apparatus includes an activated carbon device 1, a heater 2, a membrane filtration device 3, a raw water tank 4, a pretreatment device 5, An apparatus 6, and a sub tank 7 of primary pure water. In this embodiment, the pretreatment device 5 is constituted by a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 9, and a decarbonization membrane device 10 . The pretreatment apparatus 5 is provided so that treated water W1 having a chloride ion concentration of 100 ppb or less is introduced into the desalting chamber 6 of the electrodeionization apparatus 6 depending on the quality of the raw water W0.

2, the desalination chamber 11 and the concentration chamber 12 are provided in the deionized water producing apparatus 10, and the pretreatment apparatus 5 And the outlet side of the desalting chamber 11 is the flow path R2 of the desalted water W2. A part of the desalted water W2 in the desalting chamber 11 is introduced into the concentrating chamber 12 from the outlet side of the desalting chamber 11 toward the inlet side, The concentrated water W3 is introduced into the concentration chamber 12 from the direction opposite to the flow direction of the treated water W1 in the desalting chamber 11 to discharge the concentrated water W3.

The operation of the ultrapure water producing apparatus having such a construction will be described.

First, the raw water W0 is removed from the activated carbon device 1, heated to a predetermined temperature in the heater 2, and then the solid fine particles are removed from the membrane filtration device 3 to be supplied to the raw water tank 4 Once stored. Subsequently, the raw water W0 is subjected to treatment in the pretreatment device 5. [

In the pretreatment device 5, strong ionic impurities are removed by the first reverse osmosis membrane (RO) device 8 and the second reverse osmosis membrane (RO) device 9, and further, 10) removes carbonate ions (CO ₂ ).

The pretreatment apparatus 5 is designed so that the chloride ion concentration in the treated water W1 is 100 ppb or less, preferably 50 ppb or less, particularly preferably 30 ppb or less. When the chloride ion concentration in the treated water W1 exceeds 100 ppb, the removal rate of boron in the subsequent electrodeionization apparatus 6 can not be made 99% or more.

The concentration of CO ₂ in the treated water W 1 is preferably 1 ppm or less. When the CO ₂ concentration in the treated water W1 exceeds 1 ppm, the boron removal rate may be lowered to less than 99%, and in some cases to less than 90%.

Then, the treated water W1 is treated in the electrodeionization apparatus 6. In this electric deionization device 6, it is preferable to operate at a current density of 300 mA / dm ² or more. By operating at such a current density, depending on the performance of the electric deionization device, It is possible to achieve a boron removal rate of not less than 99%, particularly not less than 99.5%.

As described above, according to the pure water producing apparatus according to the present embodiment, when the boron concentration of the treated water W1 is 10 ppb or less, the desalted water W2 with a boron concentration of 100 ppt or less can be reliably obtained. If the boron removal rate of the pure water production apparatus according to the present embodiment is 99.5%, the boron concentration of the treated water W1 is 20 ppb, and furthermore, the boron removal rate is 99.8% Demineralized water (W2) having a boron concentration of 100 ppt or less can be obtained. In addition, since the boron can be sufficiently removed by the electric deionization unit 6, continuous operation is possible, and environmental load is small because no chemicals such as alkali are used. In addition, it is possible to cope with a region where the boron concentration of the water supply (raw water) is wide, and breakage does not occur compared with the boron adsorption resin, so that it becomes possible to stably supply pure water with low boron concentration over several years.

[Second Embodiment]

Next, a second embodiment of the pure water producing apparatus of the present invention will be described with reference to Fig.

3 is a flow chart showing a pure water producing apparatus according to the second embodiment.

The pure water producing apparatus according to the second embodiment is the same as the pure water producing apparatus according to the second embodiment except that the electrodeionization device according to the first embodiment described above is arranged in two stages of the first electrodeionization device 6A and the second electrodeionization device 6B And the concentrated water W3 of the second electrodeionization apparatus 6B is transferred to the treated water tank T provided at the front end of the first electrodeionization apparatus 6A.

The operation of the ultrapure water producing apparatus having such a construction will be described.

First, the raw water W0 is subjected to removal treatment of organic substances in the activated carbon device 1, heated to a predetermined temperature in the heater 2, and then solid fine particles are removed in the membrane filtration device 3, And once stored in the tank (4). Then, the raw water W0 is subjected to a treatment in the pretreatment device 5. [

In the pretreatment device 5, strong ionic impurities are removed by the first reverse osmosis membrane (RO) device 8 and the second reverse osmosis membrane (RO) device 9, and further, 10) removes carbonate ions (CO ₂ ).

The pretreatment device 5 is designed so that the chloride ion concentration in the treated water W1 is 100 ppb or less, preferably 50 ppb or less, particularly preferably 30 ppb or less. When the chloride ion concentration in the treated water W1 exceeds 100 ppb, the removal rate of the boron concentration in the subsequent electrodeionization apparatus 6A can not be made 99% or more.

The treated water W1 is continuously treated in the first and second electrodeionization apparatuses 6A and 6B and the concentrated water W3 is supplied to the first electrodeionization apparatus 6A To the processing tank T provided at the front end of the processing tank T.

It is preferable that the electric deionization apparatuses 6A and 6B are operated at a current density of 300 mA / dm ² or more. When the current density is less than 300 mA / dm ² , the boron removal rate becomes less than 99%, which is not preferable. Concretely, 99% or more of boron is removed in the first electrodeionization apparatus 6A, and 99% or more of boron is removed in the second electrodeionization apparatus 6B.

Particularly, in the present embodiment, the concentrated water W3 of the second electrodeionization apparatus 6B is transferred to the treated water tank T provided at the front end of the first electrodeionization apparatus 6A, W3 are lower in boron concentration than the treated water W1 and therefore the chloride ion concentration and the boron concentration are lower than the treated water W1 in the treated water tank T over time, Can be obtained.

The pure water producing system according to the present embodiment has been described above with reference to the drawings, but the present invention is not limited to the above embodiment, and various modifications can be made.

For example, the pretreatment apparatus 5 can supply the treated water W1 having a chloride ion concentration of not more than 100 ppb to the electrodeionization apparatus 6, and also supplies raw water W0 ). ≪ / RTI >

More specifically, the preprocessing device 5

(1) RO device + decalboxylation device

(2) The first RO device + the second RO device + decalboxylation device

(3) Ion exchange resin device (2B3T) + RO device + decarbonization membrane device

(4) Ion exchange resin device (4B5T) + RO device + decarbonization device

And so on.

The electric deionization device 6 may be a single stage, or two or three or more stages may be provided in series. If three or more stages are provided, the concentrated deionized water W3 may be joined to the treated water W1 of the first-stage electrodeionization apparatus.

Further, the electric deionization unit 6 is not particularly limited, but a vertical side surface does not transmit water, but an inclined surface can be suitably used in which a hexagonal member permeable to water is provided in the desalting chamber 11.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

In this embodiment and the comparative example, the following test apparatus was used.

Electric deionization device (product name: KCDI-UPz-150H, treated amount: 150 m3 / hr, manufactured by Kurita Kogyo Co., Ltd.)

· Reverse osmosis membrane device (product name: ES-20)

· Decarburization membrane device (product name: X-50, product of Rikisell)

[Example 1]

1 and 2, the pretreatment device 5 is connected to a first reverse osmosis membrane (RO) unit 8, a second reverse osmosis membrane (RO) unit 9, a decalboxylation unit 10, And the electric deionization units 6 were disposed in a single stage to produce a pure water producing apparatus.

As a result of treating the raw water (W0) having a boron concentration of 25 ppb, a chloride ion concentration of 11000 ppb and a CO ₂ concentration of 8 ppm by the pure water producing apparatus, the boron concentration of the treated water (W1) in the pretreatment apparatus (5) The ion concentration was 10 ppb and the CO ₂ concentration was 1 ppm or less.

The treated water W1 is treated in the electrodeionization apparatus 6 to obtain demineralized water W2 having a boron concentration of 50 ppt, a chloride ion concentration of 0.5 ppb or less, and a CO ₂ concentration of 0.01 ppm or less. At this time, the boron removal ratio in the electrodeionization apparatus 6 was 99.8%.

[Comparative Example 1]

As shown in Fig. 4, in Example 1, a pure water producing apparatus was manufactured with the same apparatus configuration except that the reverse osmosis membrane (RO) apparatus had a one-stage constitution.

As a result of treating the same raw water (WO) as in Example 1 by the pure water producing apparatus, the boron concentration of the treated water W1 in the pretreatment apparatus 5 was 25 ppb, the chloride ion concentration was 150 ppb, the CO ₂ concentration was 1 ppm or less Respectively.

The treated water W1 was treated in the electrodeionization apparatus 6 to obtain demineralized water W2 having a boron concentration of 500 ppt, a chloride ion concentration of 0.5 ppb or less, and a CO ₂ concentration of 0.01 ppm or less. At this time, the boron removal ratio in the electrodeionization apparatus 6 was 98%.

[Comparative Example 2]

The treatment was carried out in the same manner as in Example 1 except that sodium chloride was added to the treated water W1 to adjust the chloride ion concentration of the treated water W1 in the pretreatment device 5 to 150 ppb. As a result, the boron concentration was 400 ppt, (W2) having a concentration of 0.5 ppb or less and a CO ₂ concentration of 0.01 ppm or less is obtained. The boron removal rate in the electrodeionization apparatus 6 was 98.4%.

[Example 2]

3, the pretreatment device 5 is constituted by a first reverse osmosis membrane (RO) device 8, a second reverse osmosis membrane (RO) device 9 and a decarbonization membrane device 10 And the electrolytic deionization apparatuses 6A and 6B are arranged in series in two stages and the concentrated water W3 of the second electrolytic deionization apparatus 6B is supplied to the treated water Pure water producing apparatus was manufactured as a constitution to be transported to the tank (T).

The raw water (W0) having a boron concentration of 25 ppb, a chloride ion concentration of 11000 ppb and a CO ₂ concentration of 8 ppm was treated by the pure water producing apparatus so that the boron concentration of the treated water W1 of the pretreatment apparatus 5 was 25 ppb, The chloride ion concentration was 30 ppb and the CO ₂ concentration was 1 ppm or less.

The treated water W1 was continuously treated in the electric deionization units 6A and 6B so that the treated water in the treated water tank T had a boron concentration of 20 ppb and chloride ions concentration was 24ppb, CO ₂ concentration is 0.6ppm, the boron concentration in the deionized water of the electrodeionization apparatus (6A) of the first stage is 40ppt, the chloride ion concentration is 0.5ppb or less, CO ₂ concentration of not more than 0.1ppm, electrodeionization The boron removal rate in the device 6A was 99.8%. Furthermore, the boron concentration in the deionized water of the second stage electrodeionization apparatus 6B is 0.4 ppt, the chloride ion concentration is 0.5 ppb or less, the CO ₂ concentration is 0.01 ppm or less, and the boron removal rate in the electrodeionization apparatus 6B is 99 %.

[Comparative Example 3]

As a result of the treatment in the same manner as in Example 2 except that sodium chloride was added to the treated water tank T and the chloride ion concentration of the treated water W1 of the electrodeionization apparatus 6 was changed to 150 ppb, The boron concentration in the desalting water of the ion device 6A was 400 ppt, the chloride ion concentration was 0.5 ppb or less, the CO ₂ concentration was 0.01 ppm or less, and the boron removal rate in the first electrodeionization apparatus 6A was 98%. The boron concentration in the desalting water of the second electrodeionization apparatus 6B is 2 ppt, the chloride ion concentration is 0.5 ppb or less, the CO ₂ concentration is 0.01 ppm or less, and the boron removal rate in the second electrodeionization apparatus 6B is 99.5%.

5 ... Pretreatment device
6 ... Electric deionization device
6A ... The first electrodeionization apparatus
6B ... The second electrodeionization device
8… A first reverse osmosis membrane (RO) device (pretreatment device)
9 ... The second reverse osmosis membrane (RO) apparatus (pretreatment apparatus)
10 ... Decarbon film device (pretreatment device)
11 ... Desalination room
12 ... Concentration chamber
W3 ... Concentrated water
T ... Treated water tank

Claims (10)

1. A pure water producing apparatus having a pretreatment apparatus and an electric deionization apparatus for receiving treated water of the pretreatment apparatus as a desalting chamber and performing deionization treatment, wherein the deionization apparatus has a boron removal rate of 99%
Wherein the electrodeionization device is installed in two stages in series,
Wherein the pretreatment apparatus is provided with a first RO membrane device and a second RO membrane device, the chloride ion concentration of the treated water introduced into the desalting chamber of the electrodeionization device is set to 100 ppb or less, The carbonic acid concentration of the treated water to be introduced into the water is set to 1 ppm or less,
Wherein the current density during operation of the electrodeionization apparatus is 300 mA / dm ² or more.
delete The method according to claim 1,
Wherein the pretreatment apparatus further comprises one or more ion exchange resin towers. The method of claim 3,
Wherein the pretreatment apparatus further comprises a decarboxylation apparatus, a decarbonation tower, or a vacuum degassing tower. The method according to any one of claims 1, 3 and 4,
Wherein a part of the demineralized water of the electric deionization device is introduced into the concentration chamber of the electric deionization device from the direction opposite to the introduction direction of the treated water into the desalting chamber.
delete The raw water is treated in a pretreatment device and the treated water is introduced into a desalting chamber of an electric deionization device provided in series in two stages to perform deionization treatment so that the pure water having a boron removal rate of 99% A process for producing
Treating water having a chloride ion concentration of 100 ppb or less and a carbonic acid concentration of 1 ppm or less in the pretreatment apparatus having the first RO membrane apparatus and the second RO membrane apparatus is introduced into the desalting chamber of the electrodeionization apparatus, Wherein the current density during operation of the electrodeionization apparatus is 300 mA / dm ² or more.
The method of claim 7,
Wherein a part of the demineralized water of the electric deionization device is introduced into the concentration chamber of the electric deionization device from the direction opposite to the introduction direction of the treated water into the desalting chamber. delete The method of claim 7,
Wherein the concentrated water of the last stage of the electric deionization apparatus among the plurality of stages of the electric deionization apparatus is introduced into the desalting chamber of the first stage electrodeposition apparatus together with the treated water.

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