JP6863429B2 - TOC processing device and processing method - Google Patents

Description

The present invention relates to a TOC treatment apparatus and a treatment method, and more particularly to a TOC treatment apparatus and a treatment method using a UV oxidation apparatus that oxidatively decomposes an organic substance (TOC component) by irradiation with ultraviolet rays (UV).

General manufacturing systems for producing ultrapure water used in semiconductor manufacturing processes, pharmaceutical manufacturing processes, etc. from raw water such as river water, industrial water, and tap water are pretreatment systems, primary pure water systems, and secondary pure water systems. It consists of a sub-pure water production process (subsystem).

In the subsystem, generally, the primary pure water introduced into the sub tank is taken out from the primary pure water system by a pump, the water temperature of the ultrapure water is adjusted to a desired temperature by a heat exchanger, and then introduced into a UV oxidizing device. TOC in water is oxidatively decomposed by UV irradiation. The effluent from the UV oxidizing device is introduced into the ion exchange device at the subsequent stage to remove ionic substances such as carbonic acid and organic acids generated by oxidative decomposition. The ultrapure water obtained in this way is sent to the use point for use, and the surplus return water is circulated to the sub tank.

As described above, the means for oxidatively decomposing and removing organic substances in water by combining a UV oxidizing device and a subsequent ion exchange device is also applied to a primary pure water system.

Conventionally, various studies have been conducted on a TOC removal technique that combines a UV oxidizing device and an ion exchange device for the purpose of reducing and stabilizing the treated water TOC.

For example, Patent Document 1 proposes a technique for measuring the TOC of ultrapure water in an ultrapure water production system incorporating a UV oxidizing device and an ion exchange device, and controlling the inflow of raw water based on the result. There is.

This Patent Document 1 is a technique for varying the flow rate in order to control the TOC of treated water to be constant, and does not describe the production of ultrapure water having a target TOC concentration when the flow rate fluctuates.

_{Patent Document 2 proposes a technique for measuring the hydrogen peroxide (H 2} O ₂ ) concentration in the inlet water and outlet water of a UV oxidizing device and controlling the UV irradiation amount of the UV oxidizing device based on the measurement result. ing. However, since the H ₂ O ₂ concentration is not necessarily proportional to the TOC concentration, Patent Document 2 is insufficient as a control technique for the TOC concentration.

In Patent Document 3, the dissolved oxygen (DO) concentration and the TOC concentration of the outlet water of the ion exchange device at the subsequent stage of the UV oxidizing device are measured, and the UV irradiation amount of the UV oxidizing device is feedback-controlled based on these measured values. However, there is no mention of how to deal with fluctuations in flow rate.

Patent Document 4 proposes a device incorporating a means for adjusting the illuminance of a UV oxidizing device, which automatically switches between a UV lamp that is turned on or dimmed and a UV lamp that is turned off.

JP-A-2016-107249 Japanese Unexamined Patent Publication No. 2009-112941 Japanese Unexamined Patent Publication No. 2002-263634 Japanese Unexamined Patent Publication No. 2003-24774

An object of the present invention is to provide a TOC treatment apparatus and a treatment method capable of stably producing treated water having a target TOC concentration.

The TOC treatment apparatus of the present invention is a TOC treatment apparatus including an ultraviolet oxidation apparatus for decomposing TOC components by irradiating water to be treated with ultraviolet rays and a deionization apparatus in the subsequent stage, and the TOC treatment apparatus is to be treated. A flow meter for measuring the water flow rate, a TOC meter for measuring the TOC concentration of the outflow water of the deionizer, a measured value of the flow meter and a measured value of the TOC meter are input, and based on these measured values. It is characterized by comprising a control means for controlling the ultraviolet irradiation amount of the ultraviolet oxidizing apparatus.

In one aspect of the present invention, the control means is based on the difference between the product of the measured value of the flow meter and the measured value of the TOC meter and the product of the measured value of the flow meter and the target TOC value. Alternatively, the ultraviolet irradiation amount is controlled based on the value obtained by multiplying the difference between the measured value of the TOC meter and the target TOC value by the measured value of the flow meter.

The TOC treatment method of the present invention includes an ultraviolet oxidizing device that irradiates the water to be treated with ultraviolet rays to decompose the TOC component, a deionizing device in the subsequent stage, and a flow meter that measures the flow rate of the water to be treated by the ultraviolet oxidizing device. , The TOC meter that measures the TOC concentration of the effluent of the deionizer, the measured value of the flow meter, and the measured value of the TOC meter are input, and based on these measured values, the ultraviolet irradiation of the ultraviolet oxidizing device It is a TOC processing method using a control means for controlling the amount, and is a product of the measured value of the flow meter and the measured value of the TOC meter, and the product of the measured value of the flow meter and the target TOC value. It is characterized in that the ultraviolet irradiation amount is controlled based on the difference or based on the value obtained by multiplying the difference between the measured value of the TOC meter and the target TOC value by the measured value of the flow meter.

According to the TOC treatment apparatus and treatment method of the present invention, treated water having a target TOC concentration can be stably produced even if the flow rate and TOC concentration of raw water fluctuate. It is also possible to control the ultraviolet oxidizing device based on the flow rate of the ultraviolet oxidizing device and the TOC value of the inflow water to the ultraviolet oxidizing device, but in order to guarantee the water quality of the treated water, the treatment is performed in the present invention. Monitor the TOC value of water.

It is explanatory drawing of the apparatus and method of this invention. It is explanatory drawing of an Example.

Hereinafter, the present invention will be described in more detail with reference to FIG.

In FIG. 1, the water to be treated is supplied to a low-pressure ultraviolet oxidizing device (hereinafter, may be referred to as a UV device) 2 via a line 1, and the TOC component is decomposed by irradiation with ultraviolet rays. In this embodiment, the UV device 2 is a dimmable low voltage UV device.

The outflow water of the UV device 2 is supplied to the deionization device 4 via the line 3, and the deionized treated water flows out to the line 5. The deionizing device may be any of a mixed bed type ion exchange device, a two-stage ion exchange device, an electric deionization device, and the like.

A TOC total 6 is provided on the line 5, and the measured value thereof is input to the control device 7 of the UV device 2. Further, a flow meter (not shown) is provided on any of the lines 1, 3 and 5 in order to measure the flow rate of the UV device 2, and the measured value (flow rate data) is input to the control device 7.

The control device 7 calculates the product F · ΔTOC of the difference (ΔTOC) between the treated water TOC value and the target TOC value measured by the TOC total 6 and the flow rate value (F), and based on this (that is, F). Control the power input to the low voltage UV device (with the goal of zero ΔTOC). Alternatively, the control device 7 has a difference between the product of the TOC value and the flow rate value F measured by the TOC total 6 and the product of the target TOC value and the flow rate value F (the value of this difference is equal to F · ΔTOC. ) Is calculated, and the input power to the UV device 2 is controlled based on this. As the input power control method, a PID control method or the like can be adopted, but the control method is not limited to this.

In this way, the TOC value of the treated water is controlled by controlling the input power to the UV device 2 based on the TOC measured value of the treated water, the target TOC value of the treated water, and the flow rate of the treated water. Even if one or both of the flow rates of the water to be treated fluctuate, the treated water having a TOC concentration almost as targeted can be stably produced.

In this embodiment, a dimming type UV device is used as the UV device 2. A type of UV device that switches the number of UV lamps that are lit is also used for the UV device in the ultrapure water manufacturing process, but in this type, uneven irradiation of ultraviolet rays occurs when the number of lamps that are lit is reduced. As a result, the TOC value of the treated water tends to fluctuate. Therefore, in this embodiment, a dimming type UV device is adopted as the UV device 2.

In the case of this dimming type UV device, the TOC decomposition amount can be changed in the range of 1 time to 7.7 times by changing the input power in the range of 1 time to 6.6 times.

The water to be treated is preferably water that flows into the subsystem of the ultrapure water production apparatus or water that is flowing through the subsystem, but may be other water.

[Example 1]
As shown in FIG. 2, isopropyl alcohol (IPA) was added to ultrapure water by spikes to obtain water having a specified IPA concentration (that is, a specified TOC concentration). This was passed through a dimmable low-pressure UV device (output controllable range 30 to 100%) 2 for ultraviolet oxidation treatment, and then passed through a mixed-bed ion exchange tower to obtain treated water. The TOC concentration of the UV device water supply and the treated water was measured with a TOC meter.

By keeping the water flow rate ^{constant at 12 m 3} / hr and changing the IPA spike amount, the water supply TOC was changed in the range of 14 to 23 μg / L as shown in Table 1. The water flow time of each of the steps 1 to 10 in Table 1 was set to 60 min. The TOC target value of the treated water was set to 1.5 μg / L, and the input power to the UV apparatus was PID controlled based on the target value, the treated water TOC measured value, and the flow rate of the treated water. Table 1 shows the measured values of the TOC concentration of the treated water and the TOC load of the UV device ([flow rate] × [water supply TOC]).

As shown in Table 1, even if the water supply TOC fluctuates, if the TOC load is 252 mg / hr or less, the treated water TOC value is found to be stable in the range of 0.5 to 1.5 μg / L. It was also found that when the TOC loading amount exceeded 252 mg / hr, the treated water TOC value exceeded the target value (1.5 μg / L). It is considered that this is because the TOC load of the UV device exceeds the processing capacity of the UV device.

[Example 2]
In Example 1, the water supply flow ^{rate was changed at 7 to 16 m 3} / hr, and the spike amount of IPA was set to an amount proportional to the water supply flow rate so that the water supply TOC concentration was 21 μg / L. Others were tested in the same manner as in Example 1. Table 2 shows the measured values of the TOC concentration of the treated water and the TOC load of the UV device ([flow rate] × [water supply TOC]).

As shown in Table 2, even when the water supply TOC value is constant and the water supply flow rate is changed, the treated water TOC value is stable in the range of 0.5 to 1.5 μg / L if the TOC load is 252 mg / hr or less. Was allowed to do. It was also found that when the TOC loading amount exceeded 252 mg / hr, the treated water TOC value exceeded the target value (1.5 μg / L).

As is clear from Examples 1 and 2 above, according to the present invention, it is possible to supply treated water having a stable TOC concentration in the TOC removal technique using a low-pressure UV device and a deionization device.

By automatically controlling the output control of the UV device, the range of controllable TOCs increases, and the range of changes in power consumption also increases. Therefore, the present invention is also effective for power reduction and sudden TOC rise trouble.

2 Low-voltage UV device 4 Deionizer 6 TOC meter 7 Control device

Claims (3)

A TOC processing device in a primary pure water system or subsystem for producing ultrapure water.
In a TOC treatment device including an ultraviolet oxidation device that irradiates water to be treated with ultraviolet rays to decompose TOC components and a deionization device in the subsequent stage.
A flow meter that measures the flow rate of water to be treated by the ultraviolet oxidizing device,
A TOC meter that measures the TOC concentration of the effluent of the deionizer,
The measured value of the flow meter and the measured value of the TOC meter are input, and the control means for controlling the ultraviolet irradiation amount of the ultraviolet oxidizing device is provided based on these measured values .
The control means is based on the difference between the product of the measured value of the flow meter and the measured value of the TOC meter and the product of the measured value of the flow meter and the target TOC value, or the measured value of the TOC meter. A TOC processing apparatus characterized in that the ultraviolet irradiation amount is controlled based on a value obtained by multiplying the difference between the target TOC value and the target TOC value by the measured value of the flow meter. In the TOC treatment method in the primary pure water system or subsystem for ultrapure water production
An ultraviolet oxidizing device that irradiates the water to be treated with ultraviolet rays to decompose the TOC component, and a deionizing device in the subsequent stage.
A flow meter that measures the flow rate of water to be treated by the ultraviolet oxidizing device,
A TOC meter that measures the TOC concentration of the effluent of the deionizer,
It is a TOC processing method using a control means for controlling the ultraviolet irradiation amount of the ultraviolet oxidizing apparatus based on the measured values of the flow meter and the measured values of the TOC meter.
Based on the product of the measured value of the flow meter and the measured value of the TOC meter and the product of the measured value of the flow meter and the target TOC value, or the measured value of the TOC meter and the target TOC value A TOC processing method characterized in that the ultraviolet irradiation amount is controlled based on a value obtained by multiplying the difference between the above and the measured value of the flow meter. The TOC treatment method according to claim 2, wherein the ultraviolet oxidizing device is a dimming type ultraviolet oxidizing device, and the amount of ultraviolet irradiation is controlled by controlling the power input to the ultraviolet oxidizing device by PID.

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