Pure water manufacturing device

Abstract

The primary water purification device (3) is provided with a flow meter (41) at the rear stage of the ultraviolet oxidation device (13), and is provided with a control mechanism capable of controlling the ultraviolet irradiation amount of the ultraviolet oxidation device (13) on the basis of the detection value of the flow meter (41). As the ultraviolet oxidation device (13), a device which is composed of a plurality of ultraviolet lamp blocks, controls the number of lighted blocks through a control mechanism, adjusts the illuminance of the ultraviolet lamp of each block, and can control the irradiation amount of ultraviolet light in the ultraviolet oxidation device (13) is used. Furthermore, in the subsequent stage of the ultraviolet oxidation device (13), the amount of treated water is measured by a flow meter (41), and control is performed so as to increase or decrease the amount of ultraviolet irradiation in the ultraviolet oxidation device (13) on the basis of the increase or decrease of the amount of treated water with respect to the flow rate that is a reference set in advance. According to this pure water production device, the generation of hydrogen peroxide can be suppressed even if the amount of treated water varies with the amount of water used by the ultraviolet oxidation device or the like.

Description

Technical Field

[0001] The present invention relates to a pure water production device equipped with an ultraviolet oxidizing device, and more particularly to a pure water production device equipped with an ultraviolet oxidizing device whose flow rate varies depending on the amount of water used, etc. Background Art

[0002] Conventionally, ultrapure water used in the semiconductor and other electronic industries has been produced by treating raw water using an ultrapure water production apparatus consisting of a pretreatment apparatus, a primary pure water apparatus, and a secondary pure water apparatus (subsystem) for treating the primary pure water.

[0003] Usually, if Figure 1 As shown, the ultrapure water production device 1 is composed of three devices, namely, a pre-treatment device 2, a primary pure water device 3, and a secondary pure water device (subsystem) 4. In the pre-treatment device 2 of the ultrapure water production device 1, pre-treatment such as filtration, coagulation and sedimentation, and the use of a precision filtration membrane of the raw water W is carried out to mainly remove suspended matter.

[0004] The primary pure water device 3 includes, for example, a tank 11 for pre-treated water W0, a reverse osmosis membrane device 12, an ultraviolet (UV) oxidation device 13, a regenerative ion exchange device (mixed bed type or four-bed five-tower type, etc.) 14, and a membrane degassing device 15. In addition, 16 is a preheater. Here, most of the electrolytes, particles, live bacteria, etc. in the pre-treated water W0 are removed, and organic matter is decomposed.

[0005] The subsystem 4 is composed of, for example, a subtank 21 for storing the primary pure water W1 produced in the primary pure water device 3, a pump 22 for conveying the primary pure water W1 stored in the subtank 21, an ultraviolet oxidation device 24 for treating the primary pure water W1, a platinum group metal catalyst resin tower 25, a membrane degassing device 26, a reverse osmosis membrane device 27, a non-regenerative mixed bed ion exchange device 28, and an ultrafiltration (UF) membrane 29 as a membrane filtration device, and 23 is a heat exchanger. In the subsystem 4, a trace amount of organic matter (TOC (Total Organic Carbon) component) contained in the primary pure water W1 is oxidized and decomposed by ultraviolet rays in the ultraviolet oxidation device 24, hydrogen peroxide generated by the irradiation of the ultraviolet rays is decomposed in the platinum group metal catalyst resin tower 25, and dissolved gases such as DO (dissolved oxygen) mixed in are removed by the membrane degassing device 26 at the subsequent stage. Then, the residual carbonate ions, organic acids, anionic substances, and even metal ions and cationic substances are removed by reverse osmosis membrane device 27 and non-regenerative ion exchange device (DI) 28. Then, the ultrafiltration (UF) membrane 29 removes particles to become ultrapure water (secondary pure water) W2, which is supplied to the water point 5 from the delivery pipe 30, and the unused ultrapure water is returned to the sub-tank 21 from the return pipe 31.

[0006] It is known that in the ultrapure water production apparatus 1 as described above, the main purpose of the ultraviolet oxidizing device 13 is to generate a wavelength of 185 nm and decompose TOC according to the following formula (1), but hydrogen peroxide (H2O2) is generated due to the irradiation of ultraviolet rays.

[0007] Chemical formula 1

[0008]

[0009] When the hydrogen peroxide generated here flows into the equipment at the subsequent stage, especially the ion exchange device (regenerative ion exchange device 14, non-regenerative ion exchange device or electrodeionization device, etc.), it will be decomposed to produce DO (dissolved oxygen). Alternatively, hydrogen peroxide will also decompose the ion exchange resin to produce TOC. In pure water manufacturing equipment, it is mostly necessary to ensure that the DO level is less than 1μg / L. Therefore, a membrane degassing device 15 is set at the subsequent stage or the previous stage of the ion exchange device 14 to remove DO, or a platinum group metal catalyst resin tower is also set at the previous stage of the membrane degassing device 15 to completely decompose the hydrogen peroxide itself into oxygen.

[0010] However, if Figure 1 As shown, in the previous ultrapure water manufacturing device 1, the ultrapure water W2 with the maximum usage amount at the water use point (POU) 5 was produced, and the excess water was recycled. However, in recent years, energy-saving measures for pure water manufacturing devices have been promoted, and as a part of this, research has been conducted on a technology that sets the excess water that was previously circulated to only the necessary amount according to the demand water amount at the water use point (POU) 5, thereby reducing the operating energy of the water supply pump with high electricity consumption in the pure water manufacturing device, especially the supply pump of the reverse osmosis membrane (RO). Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, when the water production capacity of the pure water production device (primary pure water device 3) is increased or decreased according to the water consumption of the water point 5, if the water production capacity is reduced, for example, the ultraviolet irradiation by the ultraviolet oxidizing device is excessive (the irradiation energy of the ultraviolet lamp of the ultraviolet oxidizing device is too much relative to the TOC load of the water supply), and the amount of hydrogen peroxide generated increases. In this way, the DO at the outlet of the ion exchange device in the subsequent stage of the ultraviolet oxidizing device 13 increases.

[0013] For example, Figure 8 An example of the influence of flow rate fluctuation in the primary pure water device 3 composed of the ultraviolet oxidation device 13 and the ion exchange device 14 is schematically shown. Figure 8The case where the treated water Wx is treated by the primary pure water device 3 composed of the ultraviolet oxidation device 13 and the ion exchange device 14 to obtain the treated water Wz with a guaranteed value of DO < 5 μg / L, and the steady flow rate (100m 3 / L) compared to low flow (50m 3 / L), the H2O2 of the treated water Wy after being treated by the ultraviolet oxidation device 13 is as high as 40μg / L, and the assumed material balance changes, so the DO of the treated water Wz at the outlet of the ion exchange device 14 may become ≥5μg / L. That is, there is a problem that the guaranteed value of DO may not be met.

[0014] 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 production apparatus including an ultraviolet oxidation device capable of suppressing the generation of hydrogen peroxide even when the amount of treated water varies due to changes in the amount of used water, etc.

[0015] Means for solving problems

[0016] In view of the above-mentioned purpose, the present invention provides a pure water production device, which is a pure water production device equipped with an ultraviolet oxidation device, which treats the total organic carbon component in the treated water when the treated water volume increases or decreases by more than 5 flow% relative to the set value, wherein a detection mechanism for detecting an indicator directly or indirectly related to the concentration of H2O2 is provided in the rear section or the front section of the ultraviolet oxidation device, and a control mechanism for controlling the irradiation amount of ultraviolet rays in the ultraviolet oxidation device based on the detection value of the detection mechanism (Invention 1).

[0017] According to the above invention (Invention 1), it is generally known that the amount of H2O2 generated in the ultraviolet oxidation device is correlated with the amount of irradiation energy of the ultraviolet lamp relative to the unit water volume. Therefore, in order to reduce the amount of H2O2 generated that increases when the amount of treated water is reduced, it is necessary to reduce the irradiation energy of the ultraviolet lamp. Specifically, if the amount of treated water in the pure water manufacturing device is reduced by more than 5%, the ultraviolet irradiation amount is excessive relative to TOC, and the concentration of H2O2 increases. Therefore, in the rear section of the ultraviolet oxidation device, the concentration of H2O2 is detected, and the amount of ultraviolet irradiation in the ultraviolet oxidation device is controlled based on the detected value, so that the generation of hydrogen peroxide can be suppressed even if the amount of treated water changes.

[0018] In the above invention (Invention 1), preferably, the detection means is a flow meter, and the control means controls to increase or decrease the amount of ultraviolet irradiation as a detected value of a flow rate of the flow meter increases or decreases (Invention 2).

[0019] According to the above invention (Invention 2), the detection value of the flow meter is the amount of water treated by the ultraviolet treatment device. Therefore, if the amount of ultraviolet irradiation is the same, when the amount of treated water decreases, the concentration of H2O2 increases. Therefore, the ultraviolet treatment device is controlled to increase or decrease the amount of ultraviolet irradiation according to the increase or decrease in the amount of treated water, thereby suppressing the generation of hydrogen peroxide even if the amount of treated water changes.

[0020] In addition, in the above invention (Invention 1), it is preferred that the detection mechanism is an H2O2 meter or a dissolved hydrogen meter arranged in the rear section of the ultraviolet oxidation device, and the control mechanism controls to increase or decrease the amount of ultraviolet radiation as the detection value of the H2O2 meter or the dissolved hydrogen meter increases or decreases (Invention 3).

[0021] According to the above invention (Invention 3), if hydrogen peroxide increases, hydrogen is generated accordingly. Therefore, the ultraviolet treatment device is controlled to increase or decrease the ultraviolet irradiation amount according to the increase or decrease of the measured value of the H2O2 meter or the detected value of the dissolved hydrogen meter, so that the generation of hydrogen peroxide can be suppressed even if the treatment water amount changes.

[0022] In the above invention (Invention 1), it is preferred that the pure water production device has an ion exchange device at the rear section of the ultraviolet oxidation device, the detection mechanism is a dissolved oxygen meter arranged at the rear section of the ion exchange device, and the control mechanism controls to increase or decrease the amount of ultraviolet radiation as the detection value of the dissolved oxygen meter increases or decreases (Invention 4).

[0023] According to the above invention (Invention 4), when H2O2 passes through the ion exchange device, it becomes H2O and generates oxygen, and accordingly, the dissolved oxygen (DO) increases. Therefore, when the pure water production device has an ion exchange device at the downstream of the ultraviolet oxidation device, the concentration of dissolved oxygen is detected at the downstream of the ion exchange device, and the ultraviolet treatment device is controlled according to the increase or decrease of the detected value of the dissolved oxygen so that the ultraviolet irradiation amount is also increased or decreased, thereby suppressing the generation of hydrogen peroxide even if the amount of treated water changes.

[0024] In the above invention (Invention 1), it is preferred that the amount of power input per unit flow rate into the ultraviolet oxidation device is 0.01 to 0.3 kWh / m 3 When the maximum value of the illumination of the ultraviolet oxidation device is 100%, the illumination of the ultraviolet oxidation device can be controlled within the range of 30% to 100% (Invention 5).

[0025] According to the above invention (Invention 5), by using an ultraviolet oxidation device with a wide control range of illumination, even when the amount of water to be treated varies greatly, the illumination of the ultraviolet oxidation device can be adjusted accordingly to suppress the generation of hydrogen peroxide.

[0026] In the above inventions (Inventions 1 to 5), a TOC measuring mechanism and a flow meter may be provided in the upstream stage of the ultraviolet oxidation device (Invention 6).

[0027] According to the above invention (Invention 6), the irradiation amount of ultraviolet rays of the ultraviolet oxidizing device is preset according to the flow rate of the treated water of the ultraviolet oxidizing device and the TOC concentration of the treated water, thereby reducing the adjustment amount of the irradiation amount of ultraviolet rays.

[0028] Effects of the Invention

[0029] According to the pure water manufacturing device equipped with the ultraviolet oxidation device of the present invention, if the treated water volume of the pure water manufacturing device changes by more than 5%, especially decreases by more than 5%, the ultraviolet irradiation amount is excessive relative to TOC, and the concentration of H2O2 increases. Therefore, the concentration of H2O2 can be detected in the rear section of the ultraviolet oxidation device, and the ultraviolet irradiation amount in the ultraviolet oxidation device can be controlled based on the detected value, so that even if the treated water volume changes, the generation of hydrogen peroxide can be suppressed. As a result, it is easy to greatly change the pure water production volume in the pure water manufacturing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart showing an ultrapure water production apparatus to which the pure water apparatus of the present invention can be applied.

[0031] Figure 2 This is a flow chart schematically showing the pure water production apparatus according to the first embodiment of the present invention.

[0032] Figure 3 This is a flow chart schematically showing a pure water production apparatus according to a second embodiment of the present invention.

[0033] Figure 4 This is a flow chart schematically showing a pure water production apparatus according to a third embodiment of the present invention.

[0034] Figure 5 This is a flow chart schematically showing a pure water production apparatus according to a fourth embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram showing the change in DO accompanying the change in water volume in the pure water production apparatus according to the above embodiment.

[0036] Figure 7 This is a diagram showing the relationship between the ultraviolet oxidation device and the amount of H2O2 generated.

[0037] Figure 8 This is a schematic diagram showing the change in DO accompanying the change in water volume in a conventional pure water production apparatus. DETAILED DESCRIPTION

[0038] The pure water production device of the present invention is described below with reference to the accompanying drawings. The pure water production device of the present invention has a feature in the control of the ultraviolet oxidation device 13, and as a whole structure, it can be applied to the above-mentioned Figure 1 Therefore, in each of the following embodiments, only the relevant structure of the pure water production apparatus (primary pure water production apparatus 3) is shown, and the others are omitted.

[0039] [First embodiment]

[0040] (Pure water production equipment)

[0041] Figure 2 A pure water production device according to a first embodiment of the present invention is schematically shown. In this embodiment, a flow meter 41 is provided at the rear stage of the ultraviolet oxidation device 13, and a control mechanism (not shown) is provided that can control the irradiation amount of ultraviolet rays of the ultraviolet oxidation device 13 based on the detection value of the flow meter 41.

[0042] In this embodiment, it is preferred that the ultraviolet oxidizing device 13 is composed of a plurality of ultraviolet lamp blocks, each of which is composed of a plurality of ultraviolet lamps. The number of lighted blocks is controlled by a control mechanism, and the illumination of the ultraviolet lamps of each block is adjusted, so that the irradiation amount of ultraviolet light in the ultraviolet oxidizing device 13 can be controlled within a wide range. The ultraviolet oxidizing device 13 preferably has an electric power input per unit flow of 0.01 to 0.3 kWh / m 3, when the maximum value of the illumination of the ultraviolet oxidation device is 100%, the illumination of the ultraviolet oxidation device can be controlled within the range of 30% to 100%. Specifically, if the ultraviolet lamp block composed of one or more ultraviolet lamps is assembled into 5 blocks to form a device, and the illumination of the ultraviolet lamp of each block is adjusted within the range of 30% to 100%, since the number of lit blocks is 1 to 5, it can become an ultraviolet oxidation device 13 that can adjust the ultraviolet irradiation amount in the ultraviolet oxidation device 13 within the range of 6% to 100% relative to the maximum value of the ultraviolet irradiation amount. As the ultraviolet oxidation device 13 as described above, as a device that can adjust both the illumination of the ultraviolet lamp and the number of lit blocks, "JPW", "JPH", and "ZK-UV" manufactured by Japan Aize Industry Co., Ltd. can be used. In addition, as devices that only have the function of adjusting the illumination of the ultraviolet lamp, "COX", "WOX", and "NWOX" manufactured by Chiyoda Kohan Co., Ltd. can be cited. However, from the perspective of a wide adjustment range of the ultraviolet irradiation amount, a device that can adjust both the illumination of the ultraviolet lamp and the number of lit blocks is preferred. In particular, from the perspective of high TOC decomposition performance, "JPW" and "ZK-UV" manufactured by Nippon Aizawa Industries (PhotoScience Co., Ltd.) are preferred.

[0043] (Control method of ultraviolet oxidation device)

[0044] In this pure water device, the treated water volume is measured by the flow meter 41 at the rear stage of the ultraviolet oxidation device 13, and feedback control is performed so that when the treated water volume increases relative to the treated water volume as a preset reference, the ultraviolet irradiation amount in the ultraviolet oxidation device 13 is increased, and when it decreases, the ultraviolet irradiation amount is reduced. The relationship between the standard ultraviolet irradiation amount in the flow rate as a reference and the increase in the amount of undecomposed TOC accompanying the increase in the treated water volume and the relationship between the standard ultraviolet irradiation amount in the flow rate as a reference and the amount of H2O2 generated accompanying the decrease in the treated water volume are measured in advance, and the ultraviolet irradiation amount is controlled based on these relationships.

[0045] In addition, in the present embodiment, the flow meter 41 is provided at the rear section of the ultraviolet oxidation device 13, but it may also be provided at the inlet side for feedforward control. Furthermore, a TOC measuring mechanism may also be provided at the front section of the ultraviolet oxidation device 13, and the initial ultraviolet irradiation amount of the ultraviolet oxidation device 13 may be set using the treated water volume of the ultraviolet oxidation device 13 and the measured value of the TOC measuring mechanism.

[0046] [Second embodiment]

[0047] (Pure water production equipment)

[0048] Figure 3 A pure water production device according to a second embodiment of the present invention is schematically shown. In this embodiment, a H2O2 meter 42 is provided at the rear stage of the ultraviolet oxidation device 13, and a control mechanism (not shown) is provided that can control the irradiation amount of ultraviolet rays of the ultraviolet oxidation device 13 based on the detection value of the H2O2 meter 42.

[0049] (Control method of ultraviolet oxidation device)

[0050] In this pure water device, the H2O2 concentration of the treated water is measured by the H2O2 meter 42 at the rear stage of the ultraviolet oxidation device 13. When the H2O2 concentration increases or shows a tendency to increase, it is determined that the ultraviolet irradiation amount is excessive, and the ultraviolet irradiation amount in the ultraviolet oxidation device 13 is reduced. On the other hand, it is preferable to control to reduce the ultraviolet irradiation amount in the ultraviolet oxidation device 13 when the H2O2 concentration reaches below a predetermined level. This is because if the H2O2 concentration is too low, there is a concern that TOC will remain, and, especially in the case of Figure 1 In the ultrapure water production apparatus 1 shown, if the TOC concentration is too low in the ultraviolet oxidation device 13 of the primary pure water device 3, ultraviolet rays are excessively irradiated with respect to TOC in the ultraviolet oxidation device 24 of the subsystem 4, and H 2 O 2 is easily generated in the subsystem 4.

[0051] [Third embodiment]

[0052] (Pure water production equipment)

[0053] Figure 4 The pure water production device according to the third embodiment of the present invention is schematically shown. In this embodiment, a dissolved hydrogen (DH) meter 43 is provided at the rear stage of the ultraviolet oxidation device 13, and a control mechanism (not shown) is provided that can control the irradiation amount of ultraviolet rays of the ultraviolet oxidation device 13 based on the detection value of the DH meter 43. This is because if H2O2 is generated, hydrogen (H2) is generated according to the following formula (2), and dissolved hydrogen (DH) also increases.

[0054] 2H2O → H2O2+H2 (2)

[0055] (Control method of ultraviolet oxidation device)

[0056] In this pure water device, the dissolved hydrogen concentration of the treated water is measured by the DH meter 43 at the rear stage of the ultraviolet oxidation device 13. When the dissolved hydrogen concentration increases or shows a tendency to increase, it is determined that the ultraviolet irradiation amount is excessive, and the ultraviolet irradiation amount in the ultraviolet oxidation device 13 is reduced. On the other hand, it is preferable to control the reduction of the ultraviolet irradiation amount in the ultraviolet oxidation device 13 when the dissolved hydrogen concentration reaches below a predetermined level. This is because if the dissolved hydrogen concentration is too low, there is a concern that TOC will remain, and especially in the case of Figure 1 In the ultrapure water production apparatus 1 shown, if the TOC concentration is too low in the ultraviolet oxidation device 13 of the primary pure water device 3, ultraviolet rays are excessively irradiated with respect to TOC in the ultraviolet oxidation device 24 of the subsystem 4, and H 2 O 2 is easily generated in the subsystem 4.

[0057] [Fourth embodiment]

[0058] (Pure water production equipment)

[0059] Figure 5 A pure water production device according to a fourth embodiment of the present invention is schematically shown. In this embodiment, a dissolved oxygen (DO) meter 44 is provided at the rear section of the ion exchange device 14 provided at the rear section of the ultraviolet oxidation device 13, and a control mechanism (not shown) is provided that can control the irradiation amount of ultraviolet rays of the ultraviolet oxidation device 13 based on the detection value of the DO meter 44. This is because, if H2O2 is generated, oxygen is generated in the ion exchange device 14 according to the following formula (3), and the dissolved oxygen (DO) increases.

[0060] 2H2O2 → 2H2O+O2 (3)

[0061] (Control method of ultraviolet oxidation device)

[0062] In this pure water device, the dissolved oxygen concentration of the treated water is measured by the DO meter 44 at the rear stage of the ion exchange device 14. When the dissolved oxygen concentration increases or shows a tendency to increase, it is determined that the ultraviolet irradiation amount is excessive, and the ultraviolet irradiation amount in the ultraviolet oxidizing device 13 is reduced. On the other hand, it is preferred that when the dissolved oxygen concentration reaches or falls below a predetermined level, control is performed to reduce the ultraviolet irradiation amount in the ultraviolet oxidizing device 13.

[0063] Figure 6 FIG. 1 schematically shows an example of the influence of flow rate fluctuation when the ultraviolet oxidation device 13 is controlled as in the first to fourth embodiments. Figure 6 For the aforementioned Figure 8Similarly, when the treated water Wx is treated by the ultraviolet oxidation device 13 and the ion exchange device 14 to obtain the treated water Wz with a guaranteed value of DO<5μg / L (DO<5μg / L), at a low flow rate (50m 3 / h) by adjusting the ultraviolet irradiation amount of the ultraviolet oxidizing device 13, so that the H2O2 of the treated water Wy after treatment can be maintained at a low 20μg / L by the ultraviolet oxidizing device 13, and the influence of the change of the material balance is small, so the DO of the treated water Wz at the outlet of the ion exchange device 14 is <5μg / L, which meets the guaranteed value of DO. In addition, at low flow, in the ion exchange device 14, SV (sedimentation velocity) decreases, so DO increases, but DO can be maintained <5μg / L.

[0064] The present invention has been described above based on the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments and can be implemented in various modified forms. For example, in the fourth embodiment, if hydrogen peroxide flows into the ion exchange device 14, the ion exchange resin is decomposed to generate TOC. Therefore, a TOC meter can be provided at the rear stage of the ion exchange device 14, and the irradiation amount of ultraviolet rays of the ultraviolet oxidizing device 13 can be controlled based on the detection value of the TOC meter of the ion exchange device 14. In addition, in the case of Figure 1 In the ultrapure water production device 1 shown in the figure, the ultraviolet oxidation device 24 of the subsystem 4 can also be controlled in the same manner. Furthermore, the ultraviolet irradiation amount of the ultraviolet oxidation device 13 of the primary pure water device 3 and the ultraviolet irradiation amount of the ultraviolet oxidation device 24 of the subsystem 4 can also be coordinated and controlled.

[0065] Example

[0066] Hereinafter, the present invention will be described in more detail based on specific examples.

[0067] [Confirmation test of the amount of hydrogen peroxide produced by the control of the ultraviolet oxidation device]

[0068] (Examples 1 to 3)

[0069] Prepare ultrapure water (resistivity: above 18.1 MΩ·cm, TOC: <1μg / L, H2O2: <5μg / L, DO: <5μg / L, DH: <0.01μg / L), and add 10μg / L, 20μg / L, and 50μg / L of TOC components to the ultrapure water as test water supply (Examples 1 to 3, respectively).

[0070] As the ultraviolet oxidation device, a "JPW" manufactured by PhotoScience Co., Ltd. was prepared. The ultraviolet oxidation device has five lighted blocks of ultraviolet lamps, and the number of lighted blocks can be adjusted, and the illumination of each block of ultraviolet lamps can be adjusted to 30% to 100%.

[0071] The test water was supplied to the ultraviolet oxidation device at a predetermined flow rate, and the ultraviolet irradiation amount was adjusted to perform TOC decomposition treatment. The amount of hydrogen peroxide generated after treatment was measured, and the results are shown in FIG. Figure 7 At this time, the number of lit blocks is changed to 1, 3, and 5 (the lighting ratio is 20%, 60%, and 100%), and the dimming rate of the illumination is changed to 30%, 50%, 70%, and 100%, respectively, so that the ultraviolet irradiation amount is adjusted by a combination of the two.

[0072] according to Figure 7 It can be seen that the amount of hydrogen peroxide (H2O2) generated changes proportionally by changing the amount of ultraviolet irradiation in Examples 1 to 3. It can also be seen that the amount of hydrogen peroxide (H2O2) generated can be suppressed to about 10 μg / L or less by adjusting the amount of ultraviolet irradiation.

[0073] Description of Reference Numerals

[0074] 1: Ultrapure water production device.

[0075] 2: Pre-processing device.

[0076] 3: Primary pure water device.

[0077] 4: Secondary pure water device (auxiliary system).

[0078] 5: Use water points.

[0079] 13: Ultraviolet oxidation device.

[0080] 14: Regenerative ion exchange device.

[0081] 24: Ultraviolet oxidation device.

[0082] 25: Platinum group metal catalyst resin tower.

[0083] 41: Flow meter.

[0084] 42:H2O2 meter.

[0085] 43: Dissolved hydrogen (DH) meter.

[0086] 44 Dissolved oxygen (DO) meter. W: raw water.

[0087] W0: pre-treated water.

[0088] W1: primary pure water.

[0089] W2: secondary pure water (ultrapure water).

Claims

1. A pure water production device, which is a pure water production device equipped with an ultraviolet oxidation device, wherein the ultraviolet oxidation device treats the total organic carbon component in the treated water whose treated water volume increases or decreases by 5% or more relative to the set value, wherein: A detection mechanism for detecting an index directly or indirectly related to the concentration of H2O2 is provided at the subsequent stage or the preceding stage of the ultraviolet oxidation device, and a control mechanism for controlling the irradiation amount of ultraviolet light in the ultraviolet oxidation device based on the detection value of the detection mechanism.

2. The pure water production device according to claim 1, wherein: The detection mechanism is a flow meter, and the control mechanism controls to increase or decrease the irradiation amount of ultraviolet rays as a detected value of a flow rate of the flow meter increases or decreases.

3. The pure water production device according to claim 1, wherein: The detection mechanism is an H2O2 meter or a dissolved hydrogen meter disposed in the rear stage of the ultraviolet oxidation device, and the control mechanism controls to increase or decrease the ultraviolet irradiation amount as the detection value of the H2O2 meter or the dissolved hydrogen meter increases or decreases.

4. The pure water production device according to claim 1, wherein: The pure water production device has an ion exchange device at the downstream of the ultraviolet oxidation device, the detection mechanism is a dissolved oxygen meter arranged at the downstream of the ion exchange device, and the control mechanism controls to increase or decrease the ultraviolet irradiation amount as the detection value of the dissolved oxygen meter increases or decreases.

5. The pure water production device according to claim 1, wherein: The amount of power input per unit flow rate into the ultraviolet oxidation device is 0.01 to 0.3 kWh / m 3 When the maximum value of the illumination of the ultraviolet oxidation device is 100%, the illumination of the ultraviolet oxidation device can be controlled within a range of 30% to 100%.

6. The pure water production device according to any one of claims 1 to 5, wherein A total organic carbon measuring mechanism and a flow meter are provided at the upstream stage of the ultraviolet oxidizing device.

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