KR20190005843A - Starting method of ultrapure water producing device - Google Patents

Abstract

An object of the present invention is to provide a starting method of an ultrapure water producing apparatus (1) capable of stably obtaining ultrapure water having a very low concentration of fine particles by suppressing the hunting phenomenon of the number of fine particles after starting the production of ultrapure water. 1. A method of starting an ultra pure water producing system (1) for producing ultrapure water by supplying ultrapure water to an ultrapure water producing system (1) Pure water containing hydrogen peroxide or gas is allowed to flow or flow through the flow path of the ultrapure water producing apparatus 1 to apply vibration to at least a part of the flow path from the outside to remove fine particles adhering to the inner surface of the flow path.

Description

Starting method of ultrapure water producing device

The present invention relates to a method of starting an ultrapure water producing apparatus.

BACKGROUND ART [0002] Conventionally, ultrapure water having a very small impurity content such as ionic substances, fine particles, organic substances, dissolved gases, and live bacteria has been used in a process of manufacturing electronic parts such as semiconductor devices, liquid crystal displays, silicon wafers and printed boards. In recent years, with the improvement in the degree of integration of semiconductor devices, the demand for purity of ultrapure water has become more severe. For example, the specification of ultrapure water for semiconductor fabrication at the most advanced stage requires a resistivity of 18.2MΩ · cm or more, a particle count of 0.05μm or more is 1 / mL or less, and a total organic carbon (TOC) concentration is 1μC / L or less. It tends to disappear.

Such ultrapure water is generally manufactured by treating raw water such as industrial water, tap water, and well water in an ultrapure water production system composed of a pretreatment apparatus, a primary pure water system, and a secondary pure water system (subsystem). The produced ultrapure water is supplied to a use point as a use place.

The pretreatment apparatus is to collect raw water to obtain pretreated water by using a coagulating sedimentation apparatus or a sand filtration apparatus. The primary pure water system is appropriately selected and used as the activated carbon device, the reverse osmosis membrane device, the two-phase three-column type ion exchange resin device, the vacuum degassing device, the ultraviolet oxidation device, the mixed phase ion exchange resin device, To obtain primary pure water. The secondary pure water system (subsystem) is provided with a heat exchanger, an ultraviolet oxidation apparatus, a non-regenerative mixed ion exchange resin apparatus (Polisher), and the like on the downstream side of the (primary) pure tank temporarily storing the primary pure water. ), A demisting membrane device, an ultrafiltration device, and the like.

At the time of starting after the new installation of the ultrapure water producing apparatus, or after the restoration by the periodic inspection or the like, the ultrapure water producing apparatus is cleaned until the ultrapure water at the use point reaches the desired water quality, The starting operation is performed. Therefore, a startup period is required until ultrapure water of desired water quality can be used at the point of use at the time of starting the ultrapure water producing apparatus. However, recently, for the purpose of improving the operation efficiency of the factory, shortening of the startup period of the apparatus is strongly demanded.

As a cleaning method at the start-up operation of the ultrapure water producing apparatus, there is performed flushing / blowing by ultra pure water, circulation of ultrapure water, hot water washing, hydrogen peroxide water washing, alkaline washing (basic aqueous solution cleaning) and the like. In addition, a cleaning method using ultrapure water (functional water) or a surfactant in which a functional gas such as ozone or hydrogen is dissolved is proposed.

For example, Patent Document 1 discloses a method for removing fine particles by changing the surface potential of the fine particles adhering to the contact surface with the ultrapure water in the ultrapure water producing apparatus. Patent Document 2 discloses a process of performing circulation cleaning using a basic cleaning liquid, a process of rinsing and rinsing a basic cleaning liquid with pure water, a process of performing circulation and / or immersion cleaning using a hydrogen peroxide cleaning liquid and a process of extruding a hydrogen peroxide cleaning liquid And a step of performing rinsing with the ultrapure water.

Japanese Patent Application Laid-Open No. 2002-052322 Japanese Patent Application Laid-Open No. 2006-297180

However, in the above conventional cleaning method, the number of fine particles of 0.05 m or more can be reduced to approximately 1 pcs./mL (1000 pcs./L) or less, but the hunting phenomenon And it was found that the number of fine particles in the ultrapure water produced after the start-up operation was not stably decreased. That is, as a result of continuing the measurement of the number of particles after the start-up operation by the above-described conventional cleaning method or the like, it was found that the hunting phenomenon in which the number of fine particles temporarily rises temporarily continues for several hours to several days. In this case, in order to eliminate the hunting phenomenon, pure water is passed through the system of the ultrapure water production apparatus, but it has been found that the disappearance of the hunting phenomenon takes about one month to several months.

Furthermore, recently, as the quality of ultrapure water, it is required that the number of fine particles of 0.02 μm or more is 1 pics./mL or less. In order to obtain the above-described water quality, it has been found that it takes a long period of several months to a half year, and sometimes a half year to a year, until the hunting phenomenon after the start-up operation of the ultra pure water production apparatus by the conventional cleaning method completely disappears . Therefore, there is a need for a starting method capable of shortening the startup period.

An object of the present invention is to provide a starting method of an ultrapure water producing apparatus capable of stably obtaining ultrapure water having a very low concentration of fine particles by suppressing the hunting phenomenon of the number of fine particles after starting the production of ultrapure water do.

The method for starting the ultrapure water producing apparatus according to the present invention is an ultrapure water producing apparatus for producing ultrapure water by treating primary pure water and supplying the ultrapure water to a use site, wherein, prior to supplying the ultrapure water to the use place, Wherein pure water containing hydrogen peroxide or gas is allowed to flow or flow through the flow path of the ultrapure water producing apparatus so that at least a part of the flow path vibrates from the outside, And the fine particles are removed.

In the starting method of the ultrapure water producing apparatus of the present invention, the vibration is preferably 600 galls or more.

In the starting method of the ultrapure water producing apparatus of the present invention, the gas is preferably at least one selected from nitrogen, carbon dioxide and hydrogen. It is preferable that the water pressure of the pure water flowing into the flow path is not less than the water pressure at the time of producing the ultrapure water in the ultrapure water producing apparatus, and not more than twice the water pressure at the time of producing the ultrapure water.

In the starting method of the apparatus for producing ultrapure water of the present invention, it is preferable that the temperature of the pure water containing the hydrogen peroxide or the gas flowing through the flow path is 10 ° C to 45 ° C.

In the starting method of the ultrapure water producing apparatus of the present invention, it is preferable that the ultrapure water producing apparatus includes fine particle removing means and applies the vibration to the flow path of the fine particle removing means.

In the starting method of the ultrapure water producing apparatus of the present invention, it is preferable that the vibration is applied to at least one selected from joints, valves, bending portions and branching portions constituting the flow path of the ultrapure water producing apparatus.

In the starting method of the apparatus for producing ultrapure water of the present invention, it is preferable that oxygen generated from the hydrogen peroxide or the gas dissolves in the pure water by supersaturation.

In the starting method of the apparatus for producing ultrapure water of the present invention, it is preferable that bubbles are contained in the pure water containing the hydrogen peroxide or the gas.

In the starting method of the apparatus for producing ultrapure water of the present invention, pure water containing hydrogen peroxide or gas is preferably discharged to the outside of the ultrapure water production equipment system after passing the purified water through the flow path after removing the fine particles.

According to the starting method of the apparatus for producing ultrapure water of the present invention, it is possible to stably obtain ultrapure water having a very low concentration of fine particles by suppressing the hunting phenomenon of the number of fine particles after the start of ultrapure water production.

1 is a block diagram schematically showing an example of an ultrapure water producing apparatus which is an object of the start-up cleaning of the present invention.
2 is a block diagram schematically showing an ultrapure water producing system including the ultrapure water producing apparatus 1 shown in FIG. 1 as a secondary pure water system.
Fig. 3 is a graph showing the relationship between the elapsed time and the number of fine particles when cleaning is sufficiently performed in the examples. Fig.
4 is a graph showing the relationship between the elapsed time and the number of fine particles in the case where the cleaning is not sufficiently performed in the comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment)

As shown in Fig. 1, the ultrapure water producing apparatus 1 of the present invention, which is an object of the start-up cleaning of the present invention, is provided with a water temperature control unit (not shown) as a water treatment unit device on the downstream side of a primary pure water tank (TK) 10 for temporarily storing primary pure water (TOC-UV) 12, a membrane degasser (MDG) 13, a non-regenerative mixed-phase ion exchange resin device (Polisher) 14 And an ultrafiltration device 15 as particulate removal means for removing particulates. The ultrapure water producing apparatus 1 is connected to a use point (POU) 16 as a place where ultrapure water is used, and supplies the produced ultrapure water to the use point 16. The ultrapure water producing apparatus 1 further includes a circulation pipe 19 for circulating ultrapure water not used in the use point 16 to the primary pure water tank 10.

The ultrapure water producing apparatus 1 further includes a treatment water pipe 17 for connecting the water treatment units to each other and allowing the water to be treated to pass therethrough and a treatment water pipe 17 which is connected to the primary pure water tank 10, A pump P1 for feeding the primary pure water in the downstream side of the pump 1 and a pump P1 of the treated water pipe 17 for supplying and stopping the primary pure water to the ultrapure water producing apparatus 1 And a valve (V1) for switching. A fine particle system 25 for measuring the number of fine particles in water is connected to the rear end of the ultrafiltration device 15 of the treated water pipe 17. A drain pipe 18 for discharging water outside the system is connected to the circulation pipe 19 via a three-way valve V2.

The flow path in the ultrapure water producing apparatus 1 is constituted by a pipe or a tube. In the present embodiment, however, it is also referred to as a flow path including a tank, a pump, a joint, a valve and other facilities appropriately arranged in the middle of the flow path. The material constituting the flow path of the for-treatment water may be a material having a small amount of component elution into the ultrapure water. Examples of the material include polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyvinylidene fluoride (PVDF) , Fiber reinforced plastic (FRP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and stainless steel.

The starting method of the ultrapure water producing apparatus according to the present embodiment is characterized in that, prior to the production of the ultrapure water, for the purpose of removing fine particles adhered to the inner surface of the flow path of the ultrapure water producing apparatus 1, Is done.

First, the three-way valve V2 is switched from the side of the drain pipe 18 to the side of the primary pure water tank 10, and the valve P1 is opened to operate the pump P1. Thereby, the primary pure water (pure water) stored in the primary pure water tank 10 is passed through the ultrapure water producing apparatus 1 and circulated through the circulating pipe 19.

Then, the hydrogen peroxide or gas is dissolved in the primary pure water flowing through the ultrapure water producing apparatus 1. In the state where the primary pure water (hereinafter also referred to as " gas dissolved water ") in which the hydrogen peroxide or gas is dissolved in the flow path of the ultrapure water producing apparatus 1 is retained or circulated, Vibration is applied to a part from the outside (cleaning process).

By applying the vibration to the flow path of the ultrapure water producing apparatus 1, vibration energy is applied to the fine particles adhered to the inner surface of the flow path, whereby the fine particles are separated from the inner surface of the flow path and dispersed and removed in the gas- . Further, since the gas in the gas-dissolved water becomes bubbles, the separation of fine particles from the inner surface of the flow path can be promoted.

Further, the gas in the primary pure water has an effect of improving the removal effect of the fine particles due to vibration. That is, as a result of various studies by the inventors of the present invention, it has been found that when the gas in the primary pure water is in a state close to supersaturation or supersaturation, vibration is applied in this state, thereby improving the removal effect of the fine particles. It is also believed that hydrogen peroxide decomposes in water and becomes oxygen, thus creating the same situation.

Examples of the gas dissolved in the primary pure water include nitrogen, hydrogen, and carbon dioxide. Among them, nitrogen is preferred.

The method of dissolving hydrogen peroxide or gas in the primary pure water is not particularly limited. For example, as a method of dissolving the gas, there is a method of using the film degassing apparatus 13 as a gas dissolving apparatus and using the degassing film as a dissolving film to dissolve the gas. Since the upper portion of the primary pure water tank 10 is hermetically sealed and purged with nitrogen, nitrogen is dissolved in the primary pure water in the primary pure water tank 10. When the primary pure water is supplied from the primary pure water tank 10 in the state where the film degassing apparatus 13 is stopped, nitrogen dissolved water can be supplied.

A method of dissolving hydrogen peroxide or gas in the primary pure water includes a method of dissolving hydrogen peroxide or gas in the primary pure water circulating in the primary pure water or ultrapure water producing apparatus 1 supplied to the ultrapure water producing apparatus 1 . In this case, for example, a method of injecting pure water in which hydrogen peroxide or gas has been dissolved by a chemical pump or the like may be injected into the treated water pipe 17 immediately before the unit device or the unit group to be cleaned. Alternatively, primary pure water in which hydrogen peroxide or gas has been dissolved in advance may be supplied to the ultrapure water producing apparatus 1 to circulate the system.

The concentration of hydrogen peroxide or gas is not particularly limited as long as it is an amount capable of generating air bubbles, but it may be a state in which the gas is dissolved 1 to 3 times with respect to the solubility of hydrogen peroxide or gas at that temperature. The concentration of hydrogen peroxide or gas is preferably from 24 mg / L to 60 mg / L in the case of nitrogen, with respect to the pure water flowing through. In the case of hydrogen, it is preferably 1.2 mg / L to 3 mg / L. In the case of hydrogen peroxide, the concentration is preferably 1% by mass to 5% by mass. Thereby, the oxygen generated by the decomposition of hydrogen peroxide is in a state of 8 mg / L to 25 mg / L dissolved. The bubbles are bubbles of several microns to several hundreds of microns and can be generated by applying vibration to the primary pure water in which the oxygen or gas is dissolved by supersaturation.

The pressure at the time of supplying the gas-dissolved water by the pump P1 is not particularly limited, but it is preferably 2 times or less at a pressure of 30 to 40% lower than the supply pressure of the primary pure water to the ultrapure water producing apparatus 1 at the time of ultrapure water production . The pressure at the time of supplying the gas-dissolved water is set such that the pressure on the permeate side of the ultrafiltration device 15 in the circulation pipe 19 is not more than twice the pressure of 30-40% It is preferable that the pressure is in the approximate range. If the supply pressure of the gas-dissolved water is too small, the concentration of the dissolved water becomes insufficient, and the effect of promoting the removal of fine particles from the flow path may be deteriorated. On the other hand, when the amount is too large, when the vibration is applied, the amount of bubbles is excessively large, so that large bubbles are generated and the effect of promoting the removal of fine particles may be deteriorated. Specifically, the supply pressure of the gas-dissolved water by the pump P1 at the start-up operation is, for example, 0.2 MPa to 0.5 MPa.

In order to make the gas in the gas-dissolved water close to supersaturation or supersaturation, it is preferable to raise the water temperature of the gas-dissolved water circulated in the ultrapure water producing apparatus 1. When the water in the circulation system is cooled by the heat exchanger, the water temperature can be raised by stopping it. In addition, a heat source may be supplied to the heat exchanger to increase the water temperature.

The temperature of the gas-dissolved water flowing through the channel is preferably 10 ° C to 45 ° C, more preferably 10 ° C to 40 ° C, and still more preferably 25 ° C to 40 ° C. As a result, the solubility of the gas is lowered, thereby promoting the generation of bubbles from the gas and improving the effect of promoting the removal of fine particles from the flow path.

The valve V1, the three-way valve V2, or other valves provided in the ultrapure water circulation system may be opened or closed just before the vibration is applied or before the vibration is applied in order to make the gas in the dissolved gas water supersaturated or supersaturated. It is preferable to lower the pressure in the circulation system by adjusting the output of the pump or the like.

The flow time of the gas-dissolved water varies depending on the length and the inner diameter of the flow path constituting the ultrapure water producing apparatus 1, but may be, for example, 5 to 60 minutes. Also, the flow rate of the gas-dissolved water is not particularly limited. For example, it is preferably 0.001 m / s to 3.0 m / s, more preferably 0.5 m / s to 2.0 m / s.

In this way, when the hydrogen peroxide or gas reaches a supersaturated state at a predetermined concentration, the supply of hydrogen peroxide or nitrogen is stopped. Then, the gas-dissolved water is circulated in the system of the ultrapure water producing apparatus 1, and vibrations are applied to at least a part of the flow path of the ultrapure water producing apparatus 1 from the outside.

When the vibration is applied, the discharge pressure of the pump P1 is set to, for example, equal to or lower than the discharge pressure of the pump P1 at the time of supplying the gas dissolved water, 75%, so that the gas-dissolved water may be circulated in the ultrapure water producing apparatus 1 system. This is because, when the supply pressure of the gas-dissolved water at the time of applying the vibration is excessively high, the generation of bubbles becomes insufficient, and the effect of promoting the separation of fine particles from the flow path is lowered. When the vibration is applied, the gas dissolved water may be held in the flow path of the ultrapure water producing apparatus 1, and in this case, the pump P1 may be stopped.

The vibration applied to the flow path is preferably 600 gal or more, more preferably 700 Gal or more. The vibration applied to the flow path is preferably 100000 Gal or less. The larger the vibration applied to the flow path, the greater the effect of separating the fine particles from the inner surface of the flow path. However, if the vibration is excessively large, deterioration or breakage of the pipeline may occur.

The time to apply the vibration varies depending on the place where the vibration is applied and the magnitude of vibration, but it is about 1 to 5 minutes.

The method of applying vibration is not particularly limited, and examples thereof include a method of tapping the oil passage with a bare hand, a tool such as a wooden hammer or a hammer, and a method of applying ultrasonic vibration. Here, for example, the vibration applied to the flow path when barely tapped is about 800 Gal or more, the wooden hammer is about 1400 Gal or more, and the ultrasonic wave is about 5000 Gal or more. The vibration applied to the flow path can be measured by, for example, a vibration analyzer.

The location where the vibration is applied is not particularly limited. For example, the location where the vibration is applied is not particularly limited. For example, the treated water pipe 17 from the inlet side of the pump P1 to the use point 16, the circulation pipe 16, It is preferable that the flow passage is a connecting portion such as a valve or a joint, a bending portion or a branch portion. The fine particles are liable to stagnate and adhere to the connecting portion, or to the inner surface of the bending portion or the branch portion. According to the starting method of the present embodiment, it is possible to obtain an excellent peeling and removing effect even for such fine particles.

It is preferable that the flow path of the particulate removing means, for example, the ultrafiltration device 15 provided in the ultrapure water producing device 1 is a place where the vibration is applied. The microfilter MF or the nanofilter NF may be provided in addition to the ultrafiltration device 15. In this case, the microfilter MF or the nanofilter NF Vibration may be applied. Fine particles flowing from the upstream side of the ultrapure water producing apparatus 1 may stagnate and adhere to the inner surface of the flow path of the ultrafiltration device 15 or the microfiltration means such as the microfilter or the nanofilter. Particularly, fine particles are liable to stagnate at connecting portions such as valves and joints constituting the flow path of the ultrafiltration device 15, and at the bending portion or the branched portion. Since the hunting phenomenon tends to occur at the start of ultrapure water production by the retained fine particles, it is preferable to apply the vibration to the connecting portion and the bending portion.

Specifically, when vibrations are applied to the flow path in the apparatus constituting the particulate removing means and the flow path within 1 m each in front and rear (upstream side and downstream side) of the flow path in the apparatus, It is more effective in shortening the period.

At the start-up operation of the ultrapure water producing apparatus 1, a bypass pipe (not shown) for bypassing the non-regenerative mixed-phase ion exchange resin device 14 is provided, and a non-regenerative mixed ion exchange resin It is preferable that the device 14 is bypassed to flow the gas-dissolved water.

After the cleaning process is performed, the vibration is stopped, and thereafter, the degassing process for discharging the gas-dissolved water in the ultrapure water producing device 1 is performed. For example, it is also possible to supply the primary pure water not containing hydrogen peroxide or hydrogen gas to the ultrapure water producing apparatus 1 and also to supply the three-way valve V2 inserted into the circulation pipe 19 from the primary pure water tank 10 side Drain pipe 18 side, and the gas-dissolved water is discharged to the outside of the system through the drain pipe 18, so that the degassing process is performed.

The degassing process is performed for 30 to 300 minutes, though it depends on the size of the ultrapure water producing apparatus 1 and the flow rate of the ultrapure water. After the gas-dissolved water is sufficiently discharged from the system by the degasification step, the flushing step is subsequently performed. In the flushing process, when the non-regenerative mixed-phase ion exchange resin device 14 is bypassed, the flow path is switched from the bypass pipe to the non-regenerative mixed-phase ion exchange resin device 14. The three-way valve V2 inserted in the circulation pipe 19 is switched from the drain pipe 18 side to the primary pure water tank 10 side to circulate the ultra-pure water. It is preferable that a part of the ultrapure water circulating in the system in the flushing process is discharged to the outside of the ultrapure water producing system 1 as concentrated water of the ultrafiltration device 15, for example.

It is preferable to continuously measure the fine particles in the ultrapure water by the fine particle system 25 during the flushing process. When the ultrapure water producing apparatus 1 is thoroughly cleaned, the measured value of the fine particles gradually decreases, and finally the number of fine particles becomes 0 pcs./L. In this case, ultrapure water production can be started continuously. The fine particle system is preferably capable of measuring the number of fine particles on-line, for example, UDI-20 manufactured by Particle Measuring Systems.

On the other hand, if the particulate cleaning in the cleaning step is not sufficiently carried out, the number of fine particles does not reach 0 pcs / L, and a phenomenon (hunting phenomenon) in which the number of fine particles suddenly increases temporally occurs intermittently. This is presumably because there is a part in the flow path insufficiently washed and the fine particles are discharged from this part. In this case, since the ultrapure water quality deteriorates, it may be necessary to continue the flushing until the hunting phenomenon is reduced without initiating the ultrapure water production.

In this way, after the start-up operation of the ultrapure water producing apparatus 1 is performed, the production of the ultrapure water starts.

2 is a block diagram schematically showing an ultrapure water producing system 2 including the ultrapure water producing apparatus 1 shown in FIG. 1 as a secondary pure water system. The ultrapure water producing system 2 includes a pretreatment device 20 and a primary pure water system 30. A primary pure water tank 10 is connected to the rear end of the primary pure water system 30 and an ultrapure water producing apparatus (secondary pure water system) 1 is connected through the primary pure water tank 10.

The production of ultrapure water by the ultrapure water producing system 2 is carried out as follows. For example, raw water such as tap water, well water, and industrial water is treated in order in the pretreatment apparatus 20 and the primary pure water system 30 to produce primary pure water.

The pretreatment apparatus 20 produces pre-treated water by desorbing raw water, and is provided with, for example, a coagulating sedimentation apparatus or a sand filtration apparatus. The primary pure water system 30 treats the pretreated water to produce the primary pure water. The primary pure water system 30 includes an activated carbon device, a reverse osmosis membrane device, a cation exchange resin device, an anion exchange resin device, a two-phase three- Apparatus, an ultraviolet oxidation apparatus, a mixed-phase ion exchange resin apparatus, a precision filter, and the like. For example, the primary pure water has a resistivity value of 17 M? 占 이상 m or more, a TOC concentration of 3 占 퐂 C / L or less, and a number of particulates of 0.02 占 퐉 or more is 1 pcs./mL or less.

Subsequently, the primary pure water is once stored in the primary pure water tank 10 and then supplied to the secondary pure water system 1 (the ultrapure water producing apparatus 1 shown in FIG. 1), where ultrapure water is produced. The produced ultrapure water is supplied to the use point 16.

At this time, since the particulate adhered to the inner surface of the flow path of the secondary pure water system 1 (the ultrapure water producing apparatus 1) is removed by the starting method of the embodiment, the specific resistance value is 18.2 It is possible to supply the ultrapure water having the TOC concentration of not less than 1 占 퐂 C / L and the water quality of which the number of fine particles is not more than 1 pcs./mL stably maintained to the use point 16.

In the above description, the cleaning method of the flow path of the ultrapure water producing apparatus having the circulation pipe for supplying the ultrapure water to the circulating piping system, that is, the POU (use place), provided in the general ultrapure water producing system has been described, but the present invention is not limited thereto. For example, in the ultrapure water producing system in general, the primary pure water producing device provided upstream of the primary pure water tank 10, or the startup of the tertiary pure water producing device provided as required downstream of the ultrapure water producing device described above The present invention is not limited to this.

Example

Next, an embodiment of the present invention will be described. The present invention is not limited to the following embodiments.

(Example 1)

The starting operation was performed as follows using the same secondary pure water system as that of the ultrapure water producing apparatus shown in Fig.

The specifications of the apparatus used in Examples and Comparative Examples are as follows.

Heat Exchanger (HEX)

Plate type heat exchanger, titanium material, manufactured by HISAKA CORPORATION

Ultraviolet oxidation apparatus (TOC-UV)

Product name: SUV-ST, manufactured by Nihon Photo Science Co., Ltd.

Non-regenerative mixed-phase ion exchange resin device (Polisher)

A cationic resin and an anionic resin were mixed with 210 L of a vessel having an inner diameter of 400 mm lined with polytetrafluoroethylene, manufactured by Nomura Micro Science Co., Ltd.

The demolding device (MDG)

Product name: G284, Polyfor manufacturing

Ultrafiltration (UF)

Trade name: OLT-6036HA, manufactured by Asahi Kasei Chemicals Co., Ltd.

Online particle system

Product name: UDI-20, manufactured by Particle Measuring Systems

First, a bypass pipe bypassing the non-regenerative mixed-bed type ion exchange resin apparatus was provided, and the non-regenerated mixed-bed ion exchange resin apparatus was bypassed. The valve installed at the rear end of the first pure water tank was opened and the pump at the downstream side of the first pure water tank was operated so that the first pure water stored in the first pure water tank was passed through the second pure water system. At this time, a circulation pipe connecting the primary pure water tank was installed from the use point, and the primary pure water was circulated to the primary pure water tank. The discharge pressure of the pump was 0.3 MPa.

Further, a branch pipe was provided to the inlet side pipe of the heat exchanger, and a hydrogen pump was connected thereto, and ultrapure water (hydrogen peroxide) in which hydrogen peroxide was dissolved by the hydrogen pump was supplied to the primary pure water supplied from the primary pure water tank. The hydrogen peroxide concentration was supplied so as to be 1% by mass with respect to the primary pure water flowing into the ultrapure water producing apparatus 1. When the hydrogen peroxide solution was supplied, the discharge pressure of the pump was 0.3 MPa. Thereafter, the supply of hydrogen peroxide was stopped. The circulation of primary pure water continued.

At the same time, at the same time, the piping, the valve and the branching portion on the side of the supply water side and permeate water side of the flow path provided in the ultrafiltration device of the secondary pure water system were vibrated with a wooden hammer. The vibration applied time was 5 minutes, and the vibration caused by the wooden hammer was 1400 Gal measured by a digital vibration meter OH-580A (manufactured by Teso Co., Ltd.). When vibration was applied, the discharge pressure of the pump was not changed and was set to 0.3 MPa.

Subsequently, after the vibration is stopped, the three-way valve of the circulation pipe is switched from the first pure water tank side to the drain pipe side to discharge the ultra pure water containing hydrogen peroxide from the system to the first pure water tank, The pure water was supplied, and the secondary pure water system was rinsed to carry out the decalcification process. Thereafter, the bypass pipe was switched to the water supply for the non-regenerative mixed-phase ion exchange resin device, the three-way valve was switched from the drain piping side to the primary pure water tank side to perform the flushing process for 60 hours, Respectively. The discharge pressure of the pump at the time of producing ultrapure water was 0.3 MPa.

The number of fine particles of 0.02 占 퐉 or more in the ultrapure water after the start of the flushing process was measured and the number of times the hunting phenomenon occurred on the 2nd, 4th and 7th days was measured. The results are shown in Table 1 together with the starting operating conditions. The number of fine particles having a particle size of 0.02 占 퐉 or more was measured as the hunting phenomenon when the number of fine particles was increased as compared with that before and after the period. The number of fine particles in the hunting phenomenon is, for example, 10 pcs./L or more.

(Example 2)

In this example, the starting operation was performed in the same manner as in Example 1 except that the method of applying vibration to the flow path was changed to a method of tapping with a wooden hammer and tapping with a bare hand. The vibration applied time was 5 minutes, and the vibration when tapped with bare hands was 800 Gal in the measurement by the digital vibration system.

(Example 3)

In this example, the starting operation was performed in the same manner as in Example 1, except that the method of applying vibration to the flow path was changed to a method of applying ultrasonic waves by an ultrasonic generator ET-30S-7 (manufactured by Shimadaki Corporation). The vibration applied time was 5 minutes, and the ultrasonic vibration was 5000Gal in the measurement by the digital vibration system.

(Examples 4 to 11 and Comparative Examples 1 to 8)

The starting operation was performed in the same manner as in Example 1, except that the starting operation conditions were changed as shown in Table 1. In the above example, the heat exchanger was operated as required, and the primary pure water was heated to the temperature shown in Table 1. In the example in which all of the hydrogen peroxide and the gas were not used, the start-up operation was performed while the demineralization apparatus was operated.

In the example using nitrogen, nitrogen was dissolved using nitrogen sealed in the upper portion of the primary pure water tank, and the operation of the film degassing apparatus was stopped so that the primary pure water in which nitrogen was dissolved was passed through the flow path.

After the start-up operation, the ultra pure water production was started in the same manner as in Example 1. The number of fine particles of 0.02 占 퐉 or more in the prepared ultrapure water at the 2nd day, the 4th day and the 7th day after the start of the flushing process was measured, Are shown in Table 1 together with the results of Example 1.

The relationship between the elapsed time from the cleaning step to the flushing step in Example 1 and Comparative Example 1 and the number of fine particles is shown in the graphs of Figs.

As shown in Table 1 and FIG. 3, it was found that the hunting phenomenon was suppressed in the starting method of the ultrapure water producing apparatus of the embodiment of the present invention, and ultrapure water in which the number of fine particles was stably maintained at 1 pc / mL or less was obtained. In contrast, in Comparative Examples 1 to 8, the hunting phenomenon was not suppressed.

One… Ultrapure water production system (2nd pure water system), 2 ... Ultrapure water production system, 10 ... Primary pure water tank (TK), 11 ... Heat Exchanger (HEX), 12 ... UV oxidation system (TOC-UV), 13 ... Membrane degasser (MDG), 14 ... Non-regenerative mixed ion exchange resin device (Polisher), 15 ... Ultrafiltration device (UF), 16 ... Use point (POU), 17 ... Treatment water piping, 18 ... Blow tubing, 19 ... Circulation piping, 20 ... Pretreatment device, 30 ... First pure water system, 25 ... Particle system, P1 ... Pump, V1 ... Valves, V2 ... Three - way valve.

Claims (10)

There is provided an ultrapure water producing apparatus for producing ultrapure water by treating primary pure water and supplying the ultrapure water to a use site, the method comprising the steps of:
Pure water containing hydrogen peroxide or gas is allowed to flow or flow through the flow path of the ultrapure water producing apparatus,
Applying vibration to at least a part of the flow path from the outside,
Thereby removing fine particles adhering to the inner surface of the flow path. The method according to claim 1,
Wherein the vibration is 600 gallons or more. 3. The method according to claim 1 or 2,
Wherein the gas is at least one selected from nitrogen, carbon dioxide and hydrogen. 4. The method according to any one of claims 1 to 3,
Wherein the water pressure of the pure water containing hydrogen peroxide or gas flowing through the flow path is not more than the hydraulic pressure at the time of producing the ultrapure water in the ultrapure water producing apparatus and not more than twice the hydraulic pressure at the time of producing the ultrapure water. 5. The method according to any one of claims 1 to 4,
Wherein the temperature of the pure water containing hydrogen peroxide or gas flowing through the flow path is 10 ° C to 45 ° C. 6. The method according to any one of claims 1 to 5,
The ultrapure water producing apparatus includes fine particle removing means,
And the vibration is applied to the flow path of the fine particle removing means. 7. The method according to any one of claims 1 to 6,
Wherein the vibration is applied to at least one selected from joints, valves, bending parts and branching parts constituting the flow path of the ultrapure water producing device. 8. The method according to any one of claims 1 to 7,
Wherein oxygen generated from the hydrogen peroxide or the gas is dissolved in the pure water by supersaturation. 9. The method according to any one of claims 1 to 8,
Wherein the bubbles are contained in the pure water containing the hydrogen peroxide or the gas. 10. The method according to any one of claims 1 to 9,
Wherein pure water containing hydrogen peroxide or gas is discharged to the outside of the ultrapure water production system by passing pure water through the flow path after removing the fine particles.

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