JPH09220560A - Ultrapure water making apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase of the concn. of TOC in ultrapure water and to reduce the concn. of dissolved oxygen by successively arranging an irradiation apparatus of ultraviolet rays with a specific wavelength and a mixed bed type ion exchange apparatus through a dissolved, oxygen removing apparatus along a flow passage so as to position both of them on the upstream and downstream sides of the dissolved oxygen removing apparatus. SOLUTION: Primary pure water subjected to primary treatment by a membrane pretreatment apparatus, a reverse osmosis membrane apparatus and a mixed bed type ion exchange apparatus is subjected to secondary treatment in a secondary system containing low pressure ultraviolet lamp oxidizing devices 4, 7. These low pressure ultraviolet lamps 4, 7 have a wavelength range of 180-190nm and a mixed bed type ion exchange apparatus 5 and a vacuum degassing device 6 are arranged between both ultraviolet lamps 4, 7. Further, a mixed bed type ion exchange apparatus 8 is arranged on the downstream side of the ultraviolet lamp 7. The mixed bed type ion exchange apparatuses 5, 8 are packed with a mixture of a cation exchange resin and an anion exchange resin. The vacuum degassing apparatus 6 is packed with a packing material and a nitrogen gas adding type one bringing nitrogen gas into contact with water to be treated can be used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrapure water production system for producing ultrapure water, which is widely used in the electronics industry for producing liquid crystals and semiconductor devices, nuclear power plants, pharmaceutical production plants, etc. The present invention relates to an ultrapure water production apparatus capable of efficiently removing organic components and stably supplying ultrapure water having a low dissolved oxygen concentration to a point of use.

[0002]

2. Description of the Related Art Conventionally, liquid crystals and semiconductor elements (LS
In the process I) or the manufacturing process of pharmaceuticals, ultrapure water containing extremely small amounts of ionic substances, fine particles, organic substances, dissolved gases and viable bacteria is required. Among them,
In the electronic industry, a large amount of ultrapure water is used,
The demand for the purity of ultrapure water has become more and more strict as the integration degree of LSI has increased. In particular, ΤO in ultrapure water
Reducing the C concentration and the dissolved oxygen concentration has become a major issue.

In general, ultrapure water is produced by a pretreatment system for removing suspended matter in raw water, ionic substances, fine particles,
It is performed by a combination of a primary system for removing organic substances, dissolved gas, viable bacteria, and the like, and a secondary system for the purpose of precision finishing of primary pure water obtained from the primary system. And normally, the produced ultrapure water is supplied to the point of use and consumed in a necessary amount,
The excess amount of ultrapure water is returned to the secondary system and treated again.

However, when an excessive amount of ultrapure water is refluxed from the point of use to the secondary system, the concentration of dissolved oxygen in the secondary system remarkably rises and the purity of the produced ultrapure water deteriorates. was there.

Further, in a secondary system for the purpose of precision finishing of primary pure water, as a treatment method for reducing the concentration of organic substances in ultrapure water, a membrane treatment such as ion exchange treatment or reverse osmosis is performed. It is known that the primary pure water thus obtained is irradiated with ultraviolet rays to decompose the dissolved organic matter, and then the decomposed organic matter is removed by a mixed bed type ion exchange apparatus. In addition, as ultraviolet rays to irradiate primary pure water,
It is also known that the decomposition of dissolved organic matter can be efficiently achieved by using ultraviolet rays having a wavelength of 190 nm (particularly 184.9 nm) (JP-A-1-164488).
Issue).

However, the primary pure water, which is the water to be treated whose dissolved oxygen concentration has been reduced to a low concentration by the primary system, is combined with an ultraviolet irradiation device for generating ultraviolet rays having a wavelength of 180 to 190 nm and a mixed bed type ion exchange. When treated in a secondary system having a device, the decomposition efficiency of dissolved organic matter is low, so the TOC concentration in the water to be treated does not easily decrease. To reduce the TOC concentration, ultraviolet irradiation by an ultraviolet irradiation device is performed. Since the amount is increased, there is a problem that the power consumption of the ultraviolet irradiation device is increased.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and substantially prevents the increase of TOC concentration in ultrapure water, reduces the dissolved oxygen concentration, and reduces the operating cost. It is an object to provide an inexpensive ultrapure water production system.

[0008]

[Means for Solving the Problems] As described above, when excess treated water (ultra pure water) is refluxed from the point of use to the secondary system, the concentration of dissolved oxygen in the secondary system remarkably rises, and The purity of the purified ultrapure water deteriorated.

In addition, when the primary pure water from which dissolved oxygen has been removed is irradiated with ultraviolet rays for finishing treatment with a mixed bed type ion exchange device, the amount of power consumed by the ultraviolet irradiation device is increased in order to reduce the concentration of dissolved organic matter, and the initial This caused an increase in costs and running costs.

Therefore, as a result of intensive studies by the present inventors on these subjects, dissolved oxygen is mixed in the treated water refluxed from the point of use to the secondary system by about several ppb to several tens of ppb. It has been found. The cause of the mixing of oxygen into the treated water is unknown, but it is presumed that it is mixed from the connection part of the piping such as the cleaning device connected to the point of use.

On the other hand, 180 to 190 nm, especially 18
The decomposition reaction of dissolved organic matter by ultraviolet rays having a wavelength of 4.9 nm is as follows, and (1) OH radicals (hydroxy radicals) generated from primary pure water
(2) Organic matter in primary pure water, which is the water to be treated, is oxidatively decomposed to the stage of organic acids such as carboxylic acid, and (3) a part of it is further oxidatively decomposed to carbon dioxide. is there.

(1) H ₂ O + hν → · OH (2) R−C + · OH → RCOOΗ (3) RCOOΗ + · OH → CO ₂ + H ₂ O The above reaction is carried out under the condition that dissolved oxygen in the water to be treated is extremely small. However, under the condition that dissolved oxygen exists in the water to be treated, (4) Ozone molecules generated from the oxygen molecules cause (5) dissolved organic matter in the water to be treated to the stage of organic acids such as carboxylic acid. It is decomposed, and (6) a part is further oxidatively decomposed to carbon dioxide.

(4) 3O ₂ + hν → 2O ₃ (5) RC-O ₃ → RCOOΗ (6) RCOOΗ + O ₃ → CO ₂ + H ₂ O (7) Part of the ozone produced reacts with water. By the OH radicals, (8) the dissolved organic matter in the water to be treated is oxidatively decomposed to the stage of the organic acid such as carboxylic acid,
(9) Further, a part is oxidatively decomposed to carbon dioxide.

(7) O ₃ + H ₂ O → · OH + · OH · + O ₂ (8) RC − · OH → RCOOΗ (9) RCOOΗ + · OH → CO ₂ + H ₂ O According to the experiments by the inventors, In an ultraviolet irradiation device capable of irradiating ultraviolet rays having a wavelength of 180 to 190 nm, dissolved oxygen is simultaneously consumed when decomposing dissolved organic matter in the water to be treated, and compared with the reactions (1) to (3) above. It was suggested that the reactions (4) to (6) or (7) to (9) proceed preferentially.

That is, in the case where an ultraviolet irradiating device capable of irradiating ultraviolet rays having a wavelength of 180 to 190 nm is installed at the subsequent stage of the vacuum degassing tower, as in the conventional ultrapure water producing device, for example, Since the amount of dissolved oxygen in the treated water is remarkably reduced, compared with the case of decomposing the dissolved organic matter by irradiating ultraviolet rays having a wavelength of 180 to 190 nm in the presence of dissolved oxygen, the dissolved organic matter in the treated water is decomposed. It was speculated that the decomposition efficiency would be low.

Therefore, the ultrapure water production system according to the present invention is
A first ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, a first mixed bed ion exchange device, a dissolved oxygen removing device, and a second ultraviolet ray generator that emits ultraviolet rays having a wavelength of 180 to 190 nm. UV irradiation device, second
The mixed-bed ion exchange device of No. 1 is arranged along the flow path.

In the present invention, the amount of water to be treated is 180 to 1
It is introduced into the first ultraviolet irradiation device that generates ultraviolet rays having a wavelength of 90 nm, and the dissolved organic matter in the water to be treated is efficiently decomposed. Next, the water to be treated is introduced into the first mixed bed type ion exchange device, and the ionic components and the like in the water to be treated are removed. Next, the water to be treated is introduced into the dissolved oxygen removing device to remove oxygen and the like in the water to be treated. Next, the water to be treated is introduced into a second ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, and a trace amount of dissolved organic matter in the water to be treated is almost completely converted to an organic acid or carbon dioxide. Be disassembled. Finally, the water to be treated is introduced into the second mixed bed type ion exchange device, and a trace amount of ionic components and the like in the water to be treated are removed.

The ultrapure water producing system according to the present invention is
First to generate ultraviolet rays having a wavelength of 80 to 190 nm
Ultraviolet irradiation device, and a first mixed bed type ion exchange device,
A dissolved oxygen removing device, a second ultraviolet irradiation device for generating ultraviolet light having a wavelength of 180 to 190 nm, a second mixed bed ion exchange device, and an ultrafiltration membrane device were arranged along the flow path. The feature is that.

In the present invention, the water to be treated is 180 to 1
It is introduced into the first ultraviolet irradiation device that generates ultraviolet rays having a wavelength of 90 nm, and the dissolved organic matter in the water to be treated is efficiently decomposed. Next, the water to be treated is introduced into the first mixed bed type ion exchange device, and the ionic components and the like in the water to be treated are removed. Next, the water to be treated is introduced into the dissolved oxygen removing device to remove oxygen and the like in the water to be treated. Next, the water to be treated is introduced into a second ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, and a trace amount of dissolved organic matter in the water to be treated is almost completely converted to an organic acid or carbon dioxide. Be disassembled. Next, the water to be treated is introduced into the second mixed-bed ion exchange device, and a trace amount of ionic components in the water to be treated is removed. Finally, the water to be treated is introduced into the ultrafiltration membrane device, and the fine particles mainly containing fine nonionic substances remaining in the water to be treated are removed.

Furthermore, the ultrapure water production system according to the present invention is
A first ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, a first mixed bed ion exchange device, a dissolved oxygen removing device, and a second ultraviolet ray generator that emits ultraviolet rays having a wavelength of 180 to 190 nm. UV irradiation device, second
The mixed bed type ion exchange device and the use point for supplying the required amount of the treated water are arranged along the flow path so that an excessive amount of the treated water is refluxed from the use point to the preceding stage of the dissolved oxygen removing device. It is characterized by having done.

In the present invention, the water to be treated is 180 to 1
It is introduced into the first ultraviolet irradiation device that generates ultraviolet rays having a wavelength of 90 nm, and the dissolved organic matter in the water to be treated is efficiently decomposed. Next, the water to be treated is introduced into the first mixed bed type ion exchange device, and the ionic components and the like in the water to be treated are removed. Next, the water to be treated is introduced into the dissolved oxygen removing device to remove oxygen and the like in the water to be treated. Next, the water to be treated is introduced into a second ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, and a trace amount of dissolved organic matter in the water to be treated is almost completely converted to an organic acid or carbon dioxide. Be disassembled. Next, the water to be treated is introduced into the second mixed-bed ion exchange device, and a trace amount of ionic components in the water to be treated is removed. Next, the treated water is supplied to a point of use, a necessary amount is consumed, an excess amount of the treated water is refluxed to a stage before the dissolved oxygen removing device, and the dissolved oxygen mixed in is removed by the dissolved oxygen removing device. .

The ultrapure water producing system according to the present invention is
First to generate ultraviolet rays having a wavelength of 80 to 190 nm
Ultraviolet irradiation device, and a first mixed bed type ion exchange device,
Dissolved oxygen removal device, second ultraviolet irradiation device for generating ultraviolet light having a wavelength of 180 to 190 nm, second mixed bed ion exchange device, ultrafiltration membrane device, and supply of required amount of treated water Place points of use along the flow path,
It is characterized in that an excessive amount of treated water is refluxed from the point of use to a stage before the dissolved oxygen removing device.

In the present invention, the water to be treated is 180 to 1
It is introduced into the first ultraviolet irradiation device that generates ultraviolet rays having a wavelength of 90 nm, and the dissolved organic matter in the water to be treated is efficiently decomposed. Next, the water to be treated is introduced into the first mixed bed type ion exchange device, and the ionic components and the like in the water to be treated are removed. Next, the water to be treated is introduced into the dissolved oxygen removing device to remove oxygen and the like in the water to be treated. Next, the water to be treated is introduced into a second ultraviolet irradiation device that emits ultraviolet rays having a wavelength of 180 to 190 nm, and a trace amount of dissolved organic matter in the water to be treated is almost completely converted to an organic acid or carbon dioxide. Be disassembled. Next, the water to be treated is introduced into the second mixed-bed ion exchange device, and a trace amount of ionic components in the water to be treated is removed. Next, the water to be treated is introduced into the ultrafiltration membrane device to remove fine particles mainly composed of fine nonionic substances remaining in the water to be treated. Next, the treated water is supplied to a use point, a necessary amount is consumed, an excess amount of the treated water is refluxed to a stage before the dissolved oxygen removing device, and the dissolved oxygen mixed therein is removed by the dissolved oxygen removing device.

As described above, the essence of the present invention is to enhance the decomposition efficiency of dissolved organic matter by ultraviolet irradiation by adjusting the dissolved oxygen concentration according to the amount of dissolved organic matter in the water to be treated, the type of organic matter, etc. It also suppresses an increase in the amount. Therefore, the selection of equipment such as an ultraviolet irradiation device that generates ultraviolet rays having a wavelength of 180 to 190 nm, a mixed bed type ion exchange device, and a dissolved oxygen removing device, operating conditions, and conditions such as the flow rate of the treated water are the same as those of the treated water. It can be appropriately changed depending on the amount of dissolved organic matter and the kind of organic matter, but according to the configuration of the ultrapure water production system of the present invention, the subject of the present invention can be reliably achieved for any water to be treated. You can set the possible conditions.

In the present invention, when an excessive amount of treated water is refluxed from the point of use to the ultrapure water producing apparatus, the reflux place is not particularly limited as long as it is before the dissolved oxygen removing apparatus, and if necessary, raw water It is also possible to configure so as to merge with.

In the present invention, as the dissolved oxygen removing apparatus, (A) an inert gas-added type vacuum deaerator, (B) a membrane deaerator equipped with a gas permeable membrane or (C) a vacuum deaerator is used. It can be used depending on the conditions of the treated water. When an inert gas-added type vacuum deaerator is used, the degree of vacuum is set to 35 torr or less, and an inert gas having a volume flow ratio of 0.001 to 1.0 based on the volume of the water to be treated is introduced into the system. It is preferable to carry out vacuum deaeration treatment by feeding. When the degree of vacuum in the inert gas addition type vacuum deaerator exceeds 35 Torr, the dissolved oxygen concentration of the ultrapure water finally obtained will be 1 ppb.
It will be difficult to keep below. Further, when the volume flow ratio of the inert gas added to the inert gas addition type vacuum degasser exceeds 1.0 with respect to the volume of the water to be treated, the degassing efficiency almost reaches the ceiling. If only the running cost rises and the volume flow ratio of the inert gas added to the inert gas addition type vacuum degassing device is less than 0.001 with respect to the volume of the water to be treated, oxygen such as oxygen will be removed from the water to be treated. It becomes difficult to effectively remove the dissolved gas.

Usually, nitrogen gas, argon gas, etc. are preferably used as the inert gas added to the inert gas addition type vacuum degassing apparatus.

As the first and second ultraviolet irradiation devices, 254 nm is used as long as it emits ultraviolet light having a wavelength of 180 to 190 nm, especially 184.9 nm.
The ultraviolet rays having the sterilization wavelength may be simultaneously generated, and there is no particular limitation, but in the present invention, it is preferable to use a low-pressure ultraviolet lamp for ultraviolet oxidation.

As the first and second mixed bed type ion exchange devices, a strongly basic anion exchange resin and a cation exchange resin for removing organic acid, a trace amount of carbon dioxide or other ionic components in the water to be treated are used. A packed regenerated type or non-regenerated type mixed bed type ion exchange device can be preferably used. As the ion exchange resin used for this purpose, it is desirable that the ion exchange resin is new or free from crushing similar to it, has high ion exchange performance, and does not elute.

As the ultrafiltration membrane device, PAN,
A general ultrafiltration membrane device equipped with various ultrafiltration membranes such as cellulose acetate or fluorine can be appropriately used.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings. In each of the drawings, the same components are denoted by the same reference numerals, and detailed description will be omitted. Further, the present invention, if not departing from the gist thereof,
The present invention is not limited to this.

Example 1 and Comparative Example 1 FIG. 3 is a diagram showing an apparatus for producing primary pure water used in Example 1 and Comparative Example 1.

In FIG. 3, reference numeral 1 is a membrane pretreatment device (NML-E, Nomura Micro Science Co., Ltd.) for removing turbidity components in raw water, and reference numeral 2 is a reverse osmosis membrane device (Toray Industries, Inc. ), SU-720), reference numeral 3 is a mixed bed type ion exchange device, which is a strongly basic anion exchange resin Duolite A-113plus (ROHM &
33 liters of Haas Co., Ltd. and 23 liters of a strongly acidic cation exchange resin Duolite C-20 (Rohm & Haas Co.) as cation exchange resins, and these are regenerated in advance to obtain OH type and Η.
After being converted into a mold, it is mixed and filled. The ion exchange capacity of this mixed bed type ion exchange device is 0.9 equivalent / l-
It is Resin.

The present Example 1 and Comparative Example 1 were carried out on the primary pure water produced by the pure water producing apparatus thus constructed. As the raw water supplied to the membrane pretreatment apparatus 1, Atsugi city water was used, and the average water quality of the primary pure water produced had an electric conductivity of 16.0 MΩ · cm, TOC
The concentration was 120 ppb and the dissolved oxygen concentration was 7600 ppb.

FIG. 1 is a diagram showing the construction of an ultrapure water production system (secondary system) which is an embodiment of the present invention. In FIG. 1, symbols 4 and 7 are low-pressure ultraviolet lamp oxidizers (Chiyoda Corporation, TDFL-4, irradiation amount 0.25).
kWh / m ³⁾ and is, ultraviolet light with a peak wavelength around 185nm is irradiated. Reference numerals 5 and 8 are mixed bed type ion exchange devices, and as the anion exchange resin, a strongly basic anion exchange resin Duolite A-113plus
(Rohm & Haas Co.) 33 liters and 23 L of strong acid cation exchange resin Duolite C-20 (Rohm & Haas Co.) were used as cation exchange resins, and these were regenerated in advance and converted into OH type and H type and then mixed. It is filled.
The ion exchange capacity of this mixed bed type ion exchange device is 0.9 equivalent / l-Resin. Reference numeral 6 is a terraret S type (Nittetsu Kakohki Co., Ltd., a filling diameter of 250 m)
m, the height of the packed bed is 2000 mm) and the volume ratio of the nitrogen gas and the water to be treated is 0.03: 1, which is a nitrogen gas addition type vacuum deaerator and the degree of vacuum is maintained at 25 torr.

In this example, primary pure water produced by using the pure water producing apparatus shown in FIG. 3 was supplied to a secondary system at a flow rate of 2 m ³ / h to supply ultrapure water over time. It was carried out by continuous production (Example 1). In Example 1, the temperature of the water to be treated was kept constant at 25 ° C.

FIG. 2 is a diagram showing the configuration of an ultrapure water production system (secondary system) which is a comparative example of the present invention. In the ultrapure water production system of this comparative example, the same equipment as in Example 1 was used, except that the nitrogen gas addition type vacuum deaeration system 6 was installed in the preceding stage of the low pressure ultraviolet lamp oxidation system 4. It is exactly the same as Example 1.

In this comparative example, primary pure water produced by using the pure water producing apparatus shown in FIG. 3 was supplied to a secondary system at a flow rate of 2 m ³ / h to obtain ultrapure water over time. It was carried out by manufacturing continuously (Comparative Example 1). In Comparative Example 1, the temperature of the water to be treated was kept constant at 25 ° C.

Table 1 shows the measurement results of the TOC concentration and the dissolved oxygen concentration measured at the points of Example 1 and Comparative Example 1 (point B and point C). The TOC concentration and the dissolved oxygen concentration were measured by an online TOC meter (A-1000 S-20, Anatel).
And a sensitive dissolved oxygen meter (Orvis Fair Laboratories, Model 2713) was used. The electric conductivity of the ultrapure water obtained in Example 1 and Comparative Example 1 (electrical conductivity at points B and C) were both 1
It was 8.2 MΩ · cm.

[0040]

[Table 1] In the first embodiment, since the water to be treated introduced into the low-pressure ultraviolet lamp oxidizer 4 is the primary pure water itself, the TO
Although both the C concentration and the dissolved oxygen concentration are high, in Comparative Example 1, the treated water is degassed of the dissolved oxygen by the vacuum degassing device 6 and then introduced into the low-pressure ultraviolet lamp oxidizing device 4, so that the low pressure The water to be treated introduced into the ultraviolet lamp oxidizer 4 has a TOC concentration which is almost the same as that in Example 1, but the dissolved oxygen concentration is low. Therefore, it is estimated that in Comparative Example 1, the dissolved oxygen amount relative to the dissolved organic substance amount is lower than that in Example 1, and the decomposition efficiency of the dissolved organic substance by the low-pressure ultraviolet lamp oxidizing device 4 is low.

That is, in Example 1, when the dissolved organic matter was decomposed by the low-pressure ultraviolet lamp oxidizing device, the dissolved oxygen amount was more balanced with respect to the dissolved organic substance amount than in Comparative Example 1, so that the decomposition efficiency of the dissolved organic substance was improved. It is considered expensive.

As is clear from Table 1, the ultrapure water obtained in Example 1 has almost no change in the dissolved oxygen concentration as compared with the ultrapure water obtained in Comparative Example 1. , TOC concentration was remarkably reduced.

Example 2 and Comparative Example 2 FIG. 4 is a diagram showing the construction of an ultrapure water production system which is another example of the present invention. In FIG. 4, raw water is introduced into the pretreatment device 10, and suspended substances and the like in the raw water are separated and removed. Next, the water to be treated which has been treated by the pretreatment device 10 is introduced into the reverse osmosis device 12 after the ionic components are removed by the two beds and three columns 11 including the cation exchange resin tower, the decarboxylation tower and the anion exchange resin tower. Thus, fine particles and colloidal substances are removed.

Next, the water to be treated is introduced from the reverse osmosis device 12 into the low-pressure ultraviolet lamp oxidizing device 13 to dissolve dissolved organic matters, and the mixed bed type ion exchange device 14 removes the ionic components in the water to be treated. . Subsequently, the water to be treated is introduced into a vacuum degassing device 15 of a nitrogen gas addition system to remove dissolved gases such as dissolved oxygen, and again introduced into the low pressure ultraviolet lamp oxidizing device 16 to decompose dissolved organic matters. The mixed bed type ion exchange device 17 removes ionic components in the water to be treated. Finally, the water to be treated is introduced into the ultrafiltration membrane device 18 to remove a very small amount of fine particles and the like.

The ultrapure water produced in this manner is supplied to the use point 19 and an excessive amount of ultrapure water is returned to the stage before the vacuum degassing device 15. Further, the vacuum degassing device 15 has a volume ratio of nitrogen gas and water to be treated of 0.03: 1 and a vacuum degree of 25 torr.
It is kept at r. In addition, here, the membrane pretreatment device 10 is a pretreatment system, the two-bed three towers 11 to the vacuum degassing device 15 are the primary system systems, and the low-pressure ultraviolet lamp oxidizing device 16 to the ultrafiltration membrane device 18 are the secondary system systems. It is classified as.

For comparison with the method for producing ultrapure water of the present invention, the route A is for returning the excess amount of ultrapure water not used at the use point 19 to the subsequent stage of the vacuum degassing device 15. It is a line.

Industrial water is used as raw water to be supplied to the membrane pretreatment device 10, primary pure water is generated by the primary system, and then the primary pure water is supplied from the vacuum degassing device 15 to the secondary system. Then, ultrapure water was continuously produced over time (Example 2).

On the other hand, the route A leads to the use point 19
Ultra pure water was produced under exactly the same conditions as in Example 2, except that an excessive amount of ultra pure water was refluxed to the subsequent stage of the vacuum deaerator 15. The water temperature of the water to be treated is the same as in Example 2 and Comparative Example 2.
Both were kept constant at 25 ° C.

Table 2 shows the measurement results of the TOC concentration and the dissolved oxygen concentration measured at Point D in Example 2 and Comparative Example 2. The TOC concentration and the dissolved oxygen concentration were measured using an online TOC meter (Anatel,
A-1000 S-20) and a high-sensitivity dissolved oxygen meter (Orvisfair Laboratories, model 2713). The electric conductivity (electric conductivity at point D) of the ultrapure water obtained in Example 2 and Comparative Example 2 were both 18.2 MΩ · cm.

[0050]

[Table 2] In the second embodiment, the water to be treated is degassed with dissolved oxygen by the vacuum degassing device 15, and then the low-pressure ultraviolet lamp oxidizing device 1 is used.
6, the TOC concentration and the dissolved oxygen concentration are both low, but in Comparative Example 2, since the water to be treated from the use point 19 is directly introduced into the low-pressure ultraviolet lamp oxidizing device 16 by the route A, Although the TOC concentration of the water to be treated introduced into the low-pressure ultraviolet lamp oxidizer 16 is almost the same as that of Example 2, the dissolved oxygen concentration is high. Therefore, in Comparative Example 2, the dissolved oxygen concentration in the water to be treated was significantly higher than that in Example 2.

[0051]

According to the apparatus for producing ultrapure water of the present invention, when the primary pure water as the water to be treated is irradiated with ultraviolet rays having a wavelength of 180 to 190 nm to decompose the dissolved organic matter, Since the dissolved oxygen amount is adjusted to be almost optimal with respect to the dissolved organic matter, the dissolved organic matter in the water to be treated is efficiently decomposed. Furthermore, since excess treated water (ultra-pure water) from the point of use is refluxed to the preceding stage of the dissolved oxygen removing device, the dissolved oxygen concentration in the secondary system is prevented from increasing.
Therefore, it is possible to provide an ultrapure water production system in which the organic component and dissolved oxygen concentration in the ultrapure water are reduced and the operating cost is low.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an ultrapure water production system (secondary system) according to the present invention.

FIG. 2 is a diagram showing the configuration of an ultrapure water production system (secondary system) that is a comparative example of the present invention.

FIG. 3 is a diagram showing an apparatus (primary system) for producing primary pure water used in Example 1 and Comparative Example 1.

FIG. 4 is a diagram showing the configuration of an ultrapure water production system that is another embodiment of the present invention.

[Explanation of symbols]

1 ………… Membrane pretreatment device 2 ………… Reverse osmosis membrane device 3 ………… Mixed bed ion exchange device 4 ………… Low-pressure UV lamp oxidation device 5 ………… Mixed bed ion exchange device 6 ………… Vacuum Degassing device 7 ... Low-pressure UV lamp oxidizing device 8 ... Mixed-bed ion exchange device 9 ... Vacuum pump 10 ... Pretreatment device 11 ... 2 beds 3 towers 12 ... Reverse osmosis device 13: Low-pressure UV lamp oxidizer 14: Mixed-bed ion exchanger 15: Vacuum degasser 16: Low-pressure UV lamp oxidizer 17: Mixed-bed ion exchanger 18: Ultrafiltration Membrane Device 19 ……… Use Point

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C02F 1/44 C02F 1/44 J 1/58 1/58 T

Claims (8)

[Claims] 1. A first ultraviolet irradiation device for generating ultraviolet light having a wavelength of 180 to 190 nm, a first mixed bed ion exchange device, a dissolved oxygen removing device, and 180 to 190.
An ultrapure water production system comprising a second ultraviolet irradiation device for generating ultraviolet rays having a wavelength of nm and a second mixed bed ion exchange device arranged along a flow path. 2. A first ultraviolet irradiation device for generating ultraviolet light having a wavelength of 180 to 190 nm, a first mixed bed ion exchange device, a dissolved oxygen removing device, and 180 to 190.
Ultrapure water characterized in that a second ultraviolet irradiation device for generating ultraviolet light having a wavelength of nm, a second mixed bed ion exchange device, and an ultrafiltration membrane device are arranged along the flow path. Manufacturing equipment. 3. A first ultraviolet irradiation device that generates ultraviolet light having a wavelength of 180 to 190 nm, a first mixed bed ion exchange device, a dissolved oxygen removing device, and 180 to 190.
A second ultraviolet irradiation device for generating ultraviolet rays having a wavelength of nm, a second mixed bed ion exchange device, and a use point for supplying a necessary amount of treated water are arranged along the flow path, and the use point An excessive amount of treated water is recirculated to the upstream side of the dissolved oxygen removing device from the ultra pure water producing device. 4. A first ultraviolet irradiation device for generating ultraviolet light having a wavelength of 180 to 190 nm, a first mixed bed type ion exchange device, a dissolved oxygen removing device, and 180 to 190.
A second ultraviolet irradiation device that generates ultraviolet light having a wavelength of nm, a second mixed-bed ion exchange device, an ultrafiltration membrane device, and a point of use for supplying a required amount of treated water are provided along the flow path. An ultrapure water producing apparatus characterized in that an excessive amount of treated water is recirculated to the upstream of the dissolved oxygen removing apparatus from the point of use. 5. The dissolved oxygen removing device is an inert gas-added type vacuum deaeration device for feeding a small amount of an inert gas into the system to perform vacuum deaeration. The ultrapure water production apparatus according to any one of items 1 to 4. 6. The degree of vacuum in the inert gas addition type vacuum degassing apparatus is 35 Torr or less, and the volume flow ratio of the inert gas added to the inert gas addition type vacuum degassing apparatus is water to be treated. 6. The ultrapure water production system according to claim 5, wherein the volume is 0.001 to 1.0. 7. The ultrapure water production system according to claim 1, wherein the dissolved oxygen removing device is a membrane degassing device. 8. The ultrapure water production system according to claim 1, wherein the dissolved oxygen removing device is a vacuum degassing device.