JP2019136628A - Particle management method for ultrapure water production system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine particle management method for an ultra pure water production system capable of maintaining a state in which the number of fine particles in ultra pure water is reduced.
A sub-system 1 includes a sub-tank 2 for storing primary pure water W, a pump 4 provided at a base end portion of a supply line 3 of primary pure water W stored in the tank 2, and the pump 4 A heat exchanger 5, a low-pressure ultraviolet (UV) irradiation oxidizer 6, a non-regenerative mixed bed ion exchanger 7, and an ultrafiltration membrane (UF membrane) separator 8 as a particulate removal membrane device are provided at the subsequent stage. Have. A fine particle meter 9 is provided as a means for measuring the number of fine particles so as to be switched between the outlet side of the UF membrane separation device 8 and the outlet side of the non-regenerative mixed bed ion exchange device 7.
[Selection] Figure 1

Description

  The present invention relates to a particle management method for an ultrapure water production system, and more particularly to a particle management method for an ultrapure water production system that can maintain a reduced number of particles in ultrapure water.

  The ultrapure water production equipment used in the electronics industry is largely divided into a pretreatment device that removes turbidity from normal water such as industrial water and tap water, and a large amount of purified water from the pretreatment device. A primary pure water device for producing pure water from which impurities are partially removed, and a secondary pure water device (subsystem) for producing ultrapure water from which the primary pure water has been further refined to remove impurities completely. Consists of.

Of these, the secondary pure water device (subsystem) is basically a low-pressure ultraviolet (UV) irradiation oxidizer that decomposes organic matter, and a non-regenerative mixed bed filled with an ion exchange resin that adsorbs and removes ionic impurities. A basic ion exchange device and an ultrafiltration membrane (UF membrane) separation device for completely removing fine particles are provided as basic components, and the purity of water is further increased to ultrapure water. Here, in the low pressure UV irradiation oxidizer, TOC is decomposed into an organic acid and further to CO ₂ by ultraviolet rays having a wavelength of 185 nm emitted from a low pressure UV lamp. The decomposed organic acid and CO ₂ are removed by a subsequent ion exchange resin. In the UF membrane separator, fine particles such as outflow particles of the ion exchange resin are removed. Conventionally, nanometer-size fine particle removal processing has been performed by installing a fine particle removal film such as a UF membrane at the end of the subsystem. However, in recent years, semiconductor products have become more sophisticated and refined. Accordingly, the management of fine particles is becoming stricter. For example, in a semiconductor factory, the control value is often set to 1 particle / mL or less of particles having a diameter of 50 nm or more. For this reason, the number of fine particles in ultrapure water is measured and managed at the outlet of the UF membrane separator of the subsystem.

  A typical example of this subsystem is shown in FIG. In FIG. 5, the sub-system 21 includes a sub tank 22 for storing the primary pure water W, a pump 24 provided at the base end portion of the supply line 23 of the primary pure water W stored in the tank 22, and the pump 24, a heat exchanger 25, a low-pressure UV irradiation oxidizer 26, a non-regenerative mixed bed ion exchanger 27, and a UF membrane separator 28 provided in the subsequent stage. A fine particle meter (PC) 29 as an off-line monitor is provided on the outlet side of the UF membrane separation device 28.

  During the operation of the sub-system 21 as described above, the pump 24 is operated, and the primary pure water W in the sub-tank 22 is converted into the heat exchanger 25, the low-pressure UV irradiation oxidizer 26, and the non-regenerative mixed bed ion exchanger 27. And the UF membrane separator 28 are sequentially passed, and the obtained ultrapure water W1 is sent to the use point POU. On the other hand, the ultrapure water W1 that has not been used at the use point POU is returned to the sub tank 22 via the circulation line 23A and processed again.

  In the conventional subsystem 21 as shown in FIG. 5, the number of fine particles in the ultrapure water W1 is managed by the fine particle meter 29 on the outlet side of the UF membrane separation device 28, while the non-regenerative mixed bed ion exchange device 27 The ion load on the outlet side was measured with a conductivity meter, a specific resistance meter or the like, and was periodically exchanged when it became larger than a predetermined value. However, even with such a management method, there is a problem that the fine particles leak into the ultrapure water W1 and the number of fine particles in the ultrapure water W1 may not be maintained.

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for managing fine particles of an ultrapure water production system capable of maintaining a state in which the number of fine particles in ultrapure water is reduced. To do.

  In view of the above-mentioned object, the present invention provides fine particles of an ultrapure water production system in which primary pure water produced by a primary pure water system is treated by a subsystem having a non-regenerative mixed bed ion exchange device and a fine particle removal membrane device in this order. A management method, wherein the number of fine particles in ultrapure water at the outlet of the fine particle removal membrane device is monitored by measuring the number of fine particles, and the treated water fine particles of the non-regenerative mixed bed ion exchange device A non-regenerative mixed bed ion exchanger is replaced when the number of treated water particles in the non-regenerative mixed bed ion exchanger exceeds a predetermined value. A fine particle management method for a water production system is provided (Invention 1).

  According to this invention (Invention 1), by measuring and managing the number of fine particles of the treated water of the non-regenerative type mixed bed ion exchange device by the fine particle number measuring means, ultrapure water at the outlet of the fine particle removal membrane device It is possible to stably reduce the number of fine particles. This is presumed to be due to the following reasons. That is, when the fine particles in ultrapure water are managed only on the outlet side of the fine particle removal membrane device, the increase in fine particles can be detected when the fine particle leaks from the fine particle removal membrane device. The supply of ultrapure water having an increased number of fine particles cannot be prevented in advance. Therefore, as a result of investigating the relationship between the number of treated water particles in the non-regenerative mixed-bed ion exchanger and the number of particles in ultrapure water obtained by processing with the particle removal membrane device, the present inventors It was found that when the number of treated water particles in the mixed bed type ion exchanger increased, the particles easily leaked into the ultrapure water at the outlet of the particle removing membrane device. Therefore, by controlling the increase in the treated water particulates in this non-regenerative mixed bed ion exchange device, and confirming the number of particulates in the ultrapure water at the outlet of the particulate removal membrane device, Can be stably supplied with the number of fine particles reduced.

  In the above invention (Invention 1), the subsystem includes a low-pressure ultraviolet (UV) irradiation oxidizer, a non-regenerative mixed bed ion exchanger, and an ultrafiltration membrane (UF membrane) separator as the particulate removal membrane device. It is preferable to prepare in this order (Invention 2). In the above invention (Invention 1), the subsystem is a low-pressure ultraviolet (UV) irradiation oxidizer, a catalyst resin (hydrogen peroxide removal) device, a membrane deaerator, a non-regenerative mixed bed ion exchanger, and It is preferable to provide an ultrafiltration membrane (UF membrane) separation device as the fine particle removal membrane device in this order (Invention 3). Furthermore, in the said invention (invention 1), the said subsystem is ultrafiltration as a low-pressure ultraviolet-ray (UV) irradiation oxidation apparatus, a non-regenerative type mixed bed type ion exchange apparatus, a membrane-type deaeration apparatus, and the said fine particle removal membrane apparatus. It is preferable to provide a membrane (UF membrane) separation device in this order (Invention 4).

  According to such inventions (Inventions 2 to 4), the non-regenerative mixed bed type ion exchange device disposed in the front stage of the ultrafiltration membrane (UF membrane) separator is colloidal silica compared to ions such as sodium and chlorine. And so on, and the fine particles flow out from the ruptured part of the ultrafiltration membrane (UF membrane) separator and increase the number of fine particles in ultrapure water. When the number of fine particles in the treated water of the apparatus is controlled and the number of fine particles exceeds a predetermined value, the non-regenerative mixed bed ion exchanger is replaced, and the number of fine particles in ultrapure water at the outlet of the fine particle removal membrane apparatus By confirming the above, it is possible to prevent the ultrapure water having an increased number of fine particles from being supplied.

  In the above inventions (Inventions 1 to 4), the fine particle number measuring means is a fine particle meter, and the number of fine particles of treated water in the non-regenerative mixed bed ion exchange apparatus and ultrapure water at the outlet of the fine particle removal membrane apparatus It is preferable to measure the number of particles inside by switching one particle meter (Invention 5).

  According to this invention (Invention 5), the number of treated water particles in the non-regenerative mixed bed ion exchanger and the number of particles in ultrapure water at the outlet of the particle removal membrane device are measured with one particle meter. be able to.

  In the above inventions (Inventions 1 to 4), the fine particle number measuring means is a fine particle meter, and a fine particle meter is provided on each of the outlet side of the non-regenerative mixed bed ion exchange device and the outlet side of the fine particle removal membrane device. Thus, it is preferable to measure the number of treated water particles in the non-regenerative mixed bed ion exchanger and the number of particles in ultrapure water at the outlet of the particle removing membrane device (Invention 6).

  According to this invention (Invention 6), the number of treated water particles in the non-regenerative mixed bed ion exchanger and the number of particles in ultrapure water at the outlet of the particle removing membrane device can be measured independently. .

  The present invention measures the number of fine particles of treated water in a non-regenerative type mixed bed type ion exchange device, and when the number of fine particles exceeds a predetermined value, replaces the non-regenerative type mixed bed type ion exchange device to remove fine particles. By confirming the number of fine particles in the ultrapure water at the outlet of the membrane device, it is possible to prevent the supply of ultrapure water having an increased number of fine particles.

It is the schematic which shows the ultrapure water manufacturing system which can apply the particulate management method of the ultrapure water manufacturing system by 1st embodiment of this invention. It is the schematic which shows the ultrapure water manufacturing system which can apply the particulate management method of the ultrapure water manufacturing system by 2nd embodiment of this invention. It is the schematic which shows the ultrapure water manufacturing system which can apply the particulate management method of the ultrapure water manufacturing system by 3rd embodiment of this invention. It is the schematic which shows the ultrapure water manufacturing system which can apply the particulate management method of the ultrapure water manufacturing system by 4th embodiment of this invention. It is the schematic which shows the ultrapure water manufacturing system which can apply the particulate management method of the conventional ultrapure water manufacturing system.

  Hereinafter, the fine particle management method of the ultrapure water production system according to the first embodiment of the present invention will be described in detail with reference to FIG.

  The subsystem to which the particulate management method of the ultrapure water production system of this embodiment can be applied has basically the same configuration as that shown in FIG. That is, in FIG. 1, the sub-system 1 includes a sub-tank 2 for storing the primary pure water W, a pump 4 provided at the base end portion of the supply line 3 of the primary pure water W stored in the sub-tank 2, A heat exchanger 5, a low-pressure UV irradiation oxidizer 6, a non-regenerative mixed bed ion exchanger 7, and an ultrafiltration membrane (UF membrane) separator 8 as a fine particle removal membrane device provided at the subsequent stage of the pump 4. Have. A fine particle meter (PC) 9 is connected to the outlet side of the UF membrane separation device 8 and the outlet side of the non-regenerative mixed bed ion exchange device 7 to measure the number of fine particles in a switchable manner. As the fine particle counter 9, “K-LAMIC” (trade name) manufactured by Kurita Kogyo Co., Ltd., “UDI-50” (trade name) manufactured by PMS, or the like can be used.

  During the operation of the sub-system 1 as described above, the pump 4 is operated and the primary pure water W in the sub-tank 2 is sequentially transferred to the heat exchanger 5, the low-pressure UV irradiation oxidizer 6, and the non-regenerative mixed bed ion exchanger 7. Water is passed through and the treated water W2 of the non-regenerative mixed bed ion exchange device 7 is passed through the UF membrane separation device 8 to obtain ultrapure water W1. Then, the obtained ultrapure water W1 is supplied to the use point POU. On the other hand, the ultrapure water W1 that has not been used at the use point POU is returned to the sub tank 2 via the circulation line 3A and is processed again.

  In addition, as the ultrapure water W1 in the present embodiment, resistivity: 18.1 MΩ · cm or more, fine particles: particle size of 50 nm or more and 1000 / L or less, viable bacteria: 1 / L or less, TOC (Total Organic Carbon) ): 1 μg / L or less, Total silicon: 0.1 μg / L or less, Metals: 1 ng / L or less, Ions: 10 ng / L or less, Hydrogen peroxide: 30 μg / L or less, Water temperature: 25 ± 2 ° C. Is preferred.

Next, a particle management method for such an ultrapure water production system will be described.
[Normal operation]
In the manufacturing process of ultrapure water as described above, the fine particle counter 9 is appropriately switched between the outlet side of the UF membrane separation device 8 and the outlet side of the non-regenerative mixed bed ion exchange device 7 at predetermined timings, The number of fine particles of the ultrapure water W1 on the outlet side of the UF membrane separation device 8 and the number of fine particles of the treated water W2 of the non-regenerative mixed bed ion exchange device 7 are measured. If the number of fine particles in the ultrapure water W1 is 1 / mL or less and the number of particles in the treated water W2 of the non-regenerative mixed bed ion exchange apparatus 7 is 10 / mL or less, the operation of the sub-system 1 is performed. Continue to supply ultrapure water W1 to the use point POU.

[Particle count control]
On the other hand, even if the number of fine particles in the ultrapure water W1 on the outlet side of the UF membrane separation device 8 measured by the fine particle meter 9 which is an offline monitor is 1 / mL or less, the non-regenerative mixed bed ion exchange device 7 is used. When the number of fine particles in the treated water W2 exceeds 10 / mL, the operation of the sub-system 1 is temporarily stopped, and the non-regenerative mixed bed ion exchanger 7 is replaced. As a result, the number of fine particles of the ultrapure water W1 on the outlet side of the UF membrane separation device 8 can be maintained at 1 / mL or less, and the ultrapure water W1 with the number of fine particles exceeding the reference value is supplied to the use point POU. Can be prevented in advance. Even if such management is performed, if the number of fine particles of the ultrapure water W1 on the outlet side of the UF membrane separator 8 exceeds 1 / mL, it is determined that the UF membrane separator 8 has been broken. The UF membrane separation device 8 may be replaced.

<Action mechanism>
Such an effect is obtained by the following mechanism. That is, it is generally reported that in an ion exchange apparatus, soluble silica is very easy to remove, whereas colloidal silica is much more difficult to remove (easy to break through) than boron ("UPW Micro 2017, UPW IRDS and SEMI update "Slava Libman et al.). This boron is much more difficult to remove (easy to break through) than sodium ions (Na ⁺ ), chlorine ions (Cl ⁻ ) or carbonate ions (HCO ₃ ⁻ ) contained in the primary pure water W. . That is, colloidal silica is much easier to break through than sodium ions (Na ⁺ ), chlorine ions (Cl ⁻ ), and carbonate ions (HCO ₃ ⁻ ).

  Therefore, as a result of the study by the present inventors, the increase in the number of fine particles on the outlet side of the non-regenerative mixed bed ion exchange device 7, that is, the inlet side of the UF membrane separation device 8 is mainly caused by colloidal silica particles. I understood. Conventionally, the non-regenerative mixed bed ion exchange apparatus 7 is provided with means for measuring an ion load such as a conductivity meter and a specific resistance meter on the outlet side thereof to measure the ion load, which becomes larger than a predetermined value. However, the colloidal silica particles flow into the UF membrane separation device 8. On the other hand, by controlling the number of treated water fine particles in the non-regenerative mixed bed ion exchange device 7 as in the present embodiment, it is possible to control the fine particles before they reach the outlet of the UF membrane separation device 8. Since the regenerative mixed bed type ion exchange device 7 can be exchanged, the number of fine particles of the ultrapure water W1 at the outlet of the UF membrane separation device 8 can be stabilized. Then, it may be confirmed by measuring with the fine particle meter 9 that the number of fine particles of the ultrapure water W1 does not increase.

  As mentioned above, although 1st embodiment of this invention has been described with reference to an accompanying drawing, this invention is not restricted to the said embodiment, A various change implementation is possible. For example, as shown in FIG. 2, the first particle counter 9A is provided on the outlet side of the UF membrane separation device 8 and the second particle counter 9B is provided on the outlet side of the non-regenerative mixed bed ion exchanger 7. A configuration may be employed in which the number of fine particles in the treated water W2 of the non-regenerative mixed bed ion exchange device 7 and the number of fine particles in the ultrapure water W1 at the outlet of the UF membrane separation device 8 are independently measured. In addition, as for the fine particle count measuring means, the fine particle counter 9 and the like may be an online monitor using a centrifugal filtration method instead of an offline monitor.

  The subsystem 1 is not limited to those of the first and second embodiments described above, and can be applied to various subsystems. For example, as shown in FIG. 3, a catalyst resin (hydrogen peroxide removal) device 10 and a membrane type deaeration device 11 in which an ion exchange resin carrying a platinum group metal or the like is placed downstream of the low pressure ultraviolet (UV) irradiation oxidizer 6. And a non-regenerative mixed bed ion exchange device 7 and an ultrafiltration membrane (UF membrane) separation device 8 in this order can be suitably applied. Further, as the subsystem 1, for example, as shown in FIG. 4, a membrane deaerator 12 is provided between a non-regenerative mixed bed ion exchanger 7 and an ultrafiltration membrane (UF membrane) separator 8 It can be suitably applied to. In this case, if the particle number measuring means such as the particle counter 9 is in front of the UF membrane separation device 8 on the outlet side of the non-regenerative mixed bed ion exchange device 7, other elements such as the membrane deaeration device 12 are used. In such a case, the number of fine particles may be measured at the outlet side of another element, or may be measured immediately after the non-regenerative mixed bed ion exchange device 7.

  The following specific examples further illustrate the present invention.

[Experimental Example 1]
The ultrapure water production system shown in FIG. 1 was used to produce ultrapure water using city water as raw water. The low-pressure UV irradiation oxidizer 6 constituting the subsystem 1 is a product of Nippon Photoscience, the non-regenerative mixed bed ion exchanger 7 is “KR-FM” manufactured by Kurita Kogyo Co., Ltd., and a UF membrane separator. “KU-1510-HP-H” manufactured by Kurita Kogyo Co., Ltd. was used as 8, and “K-LAMIC” manufactured by Kurita Kogyo Co., Ltd. was used as the particle counter 9.

  In the ultrapure water production process in the ultrapure water production system, the number of fine particles in the treated water W2 of the non-regenerative mixed bed ion exchange device 7 and the ultrapure water W1 at the outlet of the UF membrane separation device 8 is monitored. When the number of fine particles of the treated water W2 of the non-regenerative type mixed bed ion exchanger 7 exceeds 10 / mL, the result of repeating the operation of replacing the non-regenerative type mixed bed ion exchanger 7 is a result of the UF membrane separation device. The number of fine particles of the ultrapure water W1 at the outlet of 8 did not exceed 1 / mL. This is considered to be because the number of fine particles caused by colloidal silica or the like in the treated water W2 flowing into the UF membrane separation device 8 can be suppressed.

[Comparative Example 1]
In Example 1, without measuring the number of fine particles of the treated water W2 of the non-regenerative mixed-bed ion exchanger 7, the specific resistance value is measured by a specific resistance meter, and the ion load is determined from the specific resistance value. As a result of repeating the operation of replacing the non-regenerative mixed bed ion exchanger 7 when the ion load exceeds a predetermined value, the number of fine particles in the ultrapure water W1 at the outlet of the UF membrane separator 8 is one over time. The tendency which exceeded / mL was shown. This is presumably because the UF membrane separation device 8 was partially broken due to deterioration with time and colloidal silica leaked.

DESCRIPTION OF SYMBOLS 1 Subsystem 2 Subtank 3 Supply line 3A Circulation line 4 Pump 5 Heat exchanger 6 Low pressure ultraviolet (UV) irradiation oxidation apparatus 7 Non-regenerative mixed bed type ion exchange apparatus 8 Ultrafiltration membrane (UF membrane) separation device (fine particle removal membrane) apparatus)
9, 9A, 9B Fine particle meter (particle number measuring means)
POU use point W Primary pure water W1 Ultra pure water W2 Non-regenerative mixed-bed ion exchanger treated water

Claims (6)

A method for managing fine particles of an ultrapure water production system in which primary pure water produced by a primary pure water system is processed by a subsystem comprising a non-regenerative mixed bed ion exchange device and a fine particle removal membrane device in this order,
While monitoring the number of fine particles in ultrapure water at the outlet of the fine particle removal film device by measuring the number of fine particles,
When the number of fine particles of treated water of the non-regenerative type mixed bed ion exchange apparatus is measured by a fine particle number measuring means, and the number of fine particles of treated water of the non-regenerative type mixed bed ion exchange apparatus exceeds a predetermined value, Replacing the non-regenerative mixed bed ion exchanger
Particle management method for ultrapure water production system.   The sub-system includes a low-pressure ultraviolet (UV) irradiation oxidizer, a non-regenerative mixed-bed ion exchanger, and an ultrafiltration membrane (UF membrane) separator as the particulate removal membrane device in this order. Particle management method for ultrapure water production system.   The sub-system is a low-pressure ultraviolet (UV) irradiation oxidizer, a catalyst resin (hydrogen peroxide removal) device, a membrane deaeration device, a non-regenerative mixed bed ion exchange device, and an ultrafiltration membrane as the particulate removal membrane device The fine particle management method for an ultrapure water production system according to claim 1, comprising a (UF membrane) separation device in this order.   The subsystem includes a low-pressure ultraviolet (UV) irradiation oxidizer, a non-regenerative mixed bed ion exchanger, a membrane deaerator, and an ultrafiltration membrane (UF membrane) separator as the particulate removal membrane device in this order. The fine particle management method of the ultrapure water production system according to claim 1.   The fine particle number measuring means is a fine particle meter, and the number of fine particles in treated water of the non-regenerative mixed bed ion exchange device and the number of fine particles in ultrapure water at the outlet of the fine particle removal membrane device are set as one fine particle meter. The fine particle management method of the ultrapure water production system according to any one of claims 1 to 4, wherein the measurement is performed by switching between the two.   The fine particle number measuring means is a fine particle meter, and a non-regenerative mixed bed ion exchange is provided by providing a fine particle meter on each of an outlet side of the non-regenerative type mixed bed ion exchange device and an outlet side of the fine particle removal membrane device. The method for managing particulates in an ultrapure water production system according to any one of claims 1 to 4, wherein the number of treated water particles in the apparatus and the number of particulates in ultrapure water at the outlet of the particulate removal membrane apparatus are respectively measured. .

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