WO2019239853A1

WO2019239853A1 - Ultrapure water producing device and ultrapure water producing method

Info

Publication number: WO2019239853A1
Application number: PCT/JP2019/020676
Authority: WO
Inventors: 清一中村
Original assignee: 野村マイクロ・サイエンス株式会社
Priority date: 2018-06-13
Filing date: 2019-05-24
Publication date: 2019-12-19
Also published as: JP2019214022A; KR20210018207A; CN112203988A

Abstract

Provided is an ultrapure water producing device that can continuously produce ultrapure water, ensuring a desired water quality, even while ion exchange resins are being replaced. This ultrapure water producing device is provided with a plurality of branch channels, a plurality of ion exchange devices, a plurality of opening/closing valves, and an aperture changing unit. The plurality of branch channels branch from a channel for water to be treated and converge on the downstream side. Each of the plurality of ion exchange devices is disposed in one of the plurality of branch channels, and each includes an ion exchange resin. Each of the plurality of opening/closing valves is disposed before and after the ion exchange device in each individual branch path. The aperture changing unit changes the apertures of the opening and closing valves along with the passage of a set time.

Description

Ultrapure water production apparatus and ultrapure water production method

The present invention relates to an ultrapure water production apparatus and an ultrapure water production method.

Conventionally, ultrapure water used in a semiconductor manufacturing process or the like is manufactured using an ultrapure water manufacturing apparatus. The ultrapure water production equipment is, for example, a pretreatment section for producing pretreated water by removing suspended substances in raw water, a reverse osmosis membrane device and an ion exchange device for all organic carbon components and ion components in the pretreated water. It is mainly composed of a primary pure water production department that produces primary pure water by removing it, and a secondary pure water production department that produces ultrapure water by removing trace amounts of impurities in the primary pure water. (For example, refer to Patent Document 1). As raw water, in addition to city water, well water, ground water, industrial water, etc., used ultrapure water (recovered water) collected at a use point where ultrapure water is used is used.

Here, the secondary pure water production department is equipped with an ion exchange device (polisher) to which an ion exchange resin is attached, in addition to an ultraviolet oxidation device and an ultrafiltration membrane device. In the ion exchange device, for example, 4 to 5 devices are arranged in parallel with respect to the flow path of the water to be treated. That is, the plurality of ion exchange devices are respectively provided for the plurality of branch flow paths that once branch the flow path of the water to be treated and merge downstream.

By the way, the ion exchange resin needs to be replaced at a cycle of, for example, about one year with the deterioration of performance over time. When exchanging the ion exchange resin, after closing valves provided before and after one ion exchange device in the branch flow path, the ion exchange resin of the ion exchange device is exchanged. Even in the process of exchanging the ion exchange resin in one ion exchange device, the production of ultra pure water is continued while operating other plural ion exchange devices that have not exchanged the ion exchange resin. Done.

Japanese Patent No. 5135654

However, when the valve is closed in the process of exchanging the ion exchange resin, the pressure loss increases as the flow rate increases in the branch flow path provided with the ion exchange device in operation. In the flow path on the downstream side of the apparatus, the pressure and flow rate vary greatly. Conventionally, the operation is performed manually and the above-mentioned valve of the ion exchange resin device is manually operated, and the discharge valve of the inlet side pump is manually operated while observing the pressure and flow fluctuations in the flow path downstream of the ion exchange device. The operation of keeping the flow path pressure and flow rate downstream of the ion exchange device constant was performed carefully. In recent years, the fluctuating flow rate and pressure are controlled by the amount of water supplied to the pump in accordance with the flow meter and pressure gauge measurement value, but due to the conventional valve mechanism, the flow rate and pressure are short, such as 3 to 5 seconds. As a result, the valve is suddenly closed, so that the above-described control cannot follow the rapid flow rate and pressure fluctuation.

When the flow rate or pressure in the flow path of treated water or ultrapure water to be manufactured fluctuates significantly, fine particles such as metal colloids from the water flow contact surface made of metal such as an ultraviolet oxidizer or pump Will occur. In the generated fine particles such as metal colloid, the metal component may be gradually ionized and dissolved in water. At this time, the amount of residual ions in the water increases due to the dissolved metal ions, which leads to a deterioration in the quality of the ultrapure water produced.

In addition, when the flow rate or pressure in the flow path of treated water or ultrapure water to be manufactured fluctuates greatly, the fluctuations cause the structural reservoirs such as ultraviolet oxidizers and pumps, pipes and valve members, etc. Substances that deteriorate the water quality, such as fine particles remaining in the reservoir due to the stable water flow, may flow out. At this time, the quality of the produced ultrapure water is deteriorated. Furthermore, for example, when the supply pressure of the ultrapure water to be manufactured fluctuates, the flow rate of pure water in the semiconductor manufacturing equipment connected to the place of use (POU) fluctuates, which may affect the yield. is there.

The present invention has been made to solve the above-mentioned problems, and continuously produces ultrapure water having a desired water quality even when the ion exchange resin provided in the ultrapure water production apparatus is replaced. An object of the present invention is to provide an ultrapure water production apparatus and a method for producing ultrapure water.

The ultrapure water production apparatus of the present invention includes a plurality of branch channels, a plurality of ion exchange devices, a plurality of on-off valves, and an opening degree changing unit. The plurality of branch flow paths branch the flow path of the water to be treated and merge on the downstream side. The plurality of ion exchange devices are respectively provided on the plurality of branch channels and each have an ion exchange resin. The plurality of on-off valves are respectively provided before and after each ion exchange device on each branch flow path. The opening degree changing unit changes the opening degree of the on-off valve as the set time elapses.

Moreover, the ultrapure water production apparatus of the present invention includes a primary pure water production unit and a secondary pure water production unit. The primary pure water production unit removes organic components and ionic components from the pretreated water obtained by pretreating raw water to produce primary pure water. On the other hand, the secondary pure water production section produces secondary pure water that becomes ultrapure water by removing impurities in the produced primary pure water. The plurality of branch channels, the plurality of ion exchange devices, and the plurality of on-off valves described above are provided in the secondary pure water production unit.

Furthermore, the opening degree change unit in the ultrapure water production apparatus of the present invention individually sets a time interval for changing the opening degree and a change amount of the opening degree. Further, the opening degree changing unit selectively changes the opening degree of any one of the plurality of on-off valves.

Furthermore, the ultrapure water production apparatus of the present invention includes a pump, a measuring instrument, and an inverter. The pump is provided on the pre-branch channel upstream of the plurality of branch channels. The measuring instrument is provided on the flow path that merges on the downstream side of the plurality of branch flow paths, and measures the flow rate or pressure in the merged flow path. The inverter controls the operation of the pump based on the measurement result by the measuring instrument.

Furthermore, the ultrapure water production method of the present invention provides ultrapure water using the ultrapure water production apparatus comprising the plurality of branch channels, the plurality of ion exchange devices, the plurality of on-off valves, and the opening changing unit. In the manufacturing method, the opening / closing valves before and after the ion exchange device provided in one of the plurality of branch channels through which the water to be treated circulate are all opened by the opening changing unit. A step of closing, a step of exchanging the ion exchange resin of the ion exchange device in which the front and rear on-off valves are fully closed, and a change in the opening of the front and rear on-off valves that are fully closed after the exchange of the ion exchange resin. And a step of fully opening each part.

ADVANTAGE OF THE INVENTION According to this invention, the ultrapure water manufacturing apparatus and ultrapure water manufacture which can manufacture continuously the ultrapure water with which the desired water quality was ensured also at the time of replacement | exchange of the ion exchange resin provided in the ultrapure water manufacturing apparatus. It is possible to provide a method.

The block diagram which shows roughly the structure of the ultrapure water manufacturing apparatus which concerns on embodiment of this invention. The block diagram which shows the structure of the secondary pure water manufacturing part with which the ultrapure water manufacturing apparatus of FIG. 1 is provided. The block diagram which shows the structure of the control system containing the opening degree change part with which the ultrapure water manufacturing apparatus of FIG. 1 is provided. FIG. 4 is a diagram schematically showing valve opening gradient control over time by the opening changing unit of FIG. 3. The figure which shows the fluctuation | variation of the pressure (or flow volume) and inverter output in the flow path of the downstream in the process of fully closing the valve of one polisher with which the secondary pure water manufacturing part of FIG. 2 is provided. The block diagram which shows the structure of the control system in the secondary pure water manufacturing part with which the ultrapure water manufacturing apparatus of the comparative example was equipped. The figure which shows the fluctuation | variation of the pressure (or flow volume) and inverter output in the flow path of the downstream in the process of fully closing the valve of one polisher with which the secondary pure water manufacturing part of FIG. 6 is provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the ultrapure water production apparatus 10 according to the present embodiment includes a pretreatment unit 12, a primary pure water production unit 14, a tank 16, and a secondary pure water production unit 18. The pretreatment unit 12 introduces city water, well water, industrial water, and the like as raw water. This pretreatment part 12 is suitably constituted according to the quality of raw water, etc., and removes suspended matter of raw water and generates pretreatment water. The pretreatment unit 12 includes, for example, a sand filtration device or a microfiltration device, and further includes a heat exchanger for adjusting the temperature of the water to be treated as necessary.

The primary pure water production unit 14 produces primary pure water by removing organic components, ionic components, dissolved gas, and the like in the pretreatment water, and supplies the primary pure water to the tank 16. The primary pure water production unit 14 includes, for example, a reverse osmosis membrane device, an ion exchange device (a cation exchange device, an anion exchange device, a mixed bed ion exchange device, etc.), an ultraviolet oxidation device, and a deaeration device (vacuum deaeration). One or more of a device, a degassing membrane device, etc.). The primary pure water has, for example, a total organic carbon (TOC) concentration of 5 μg C / L or less and a resistivity of 17 MΩ · cm or more. The tank 16 stores primary pure water and supplies the necessary amount to the secondary pure water production unit 18.

On the other hand, the secondary pure water production unit 18 produces secondary pure water that becomes ultrapure water by removing impurities in the primary pure water produced by the primary pure water production unit 14, and uses the ultrapure water. To the use point POU (Point Of Use). The extra ultrapure water that has passed through the use point POU is collected in the tank 16.

More specifically, as shown in FIG. 2, the secondary pure water production unit 18 includes a circle pump (treated water supply pump) 11, a heat exchanger 17, an ultraviolet oxidizer (TOC-UV) 19, an treated object. .., 8n, a plurality of on-off valves 3a, 3b,... 3n and outlet valves 4a, 4b,... 4n, a plurality of ion exchangers, polishers 1a, 1b. ... 1n, a deaeration device 21, a pressure gauge (PI) 23 as a measuring instrument, and a flow meter (FI) 24 are provided.

Further, as shown in FIG. 2, the secondary pure water production unit 18 includes a pressure switch 15 as a measuring instrument, a booster pump (treated water pressurizing pump) 20, a plurality of

branch channels

9a, 9b,. .., 5n and outlet valves 6a, 6b... 6n, polishers 2a, 2b... 2n as a plurality of ion exchange devices, an ultrafiltration membrane device 22, a flow meter 26 as a measuring instrument, A pressure control valve (automatic pressure control valve: PCV) 29 and a pressure gauge 27 are provided.

The circle pump 11 is provided on the pre-branch channel 7 upstream of the plurality of branch channels 8a, 8b,. The circle pump 11 supplies primary pure water (treated water) accommodated in the tank 16 to the heat exchanger 17. The heat exchanger 17 adjusts the temperature of primary pure water supplied from the circle pump 11. At this time, the temperature of the primary pure water is preferably adjusted to, for example, 25 ± 3 ° C. by the heat exchanger 17.

The ultraviolet oxidizer 19 irradiates the primary pure water whose temperature is adjusted by the heat exchanger 17 with ultraviolet rays, and decomposes and removes trace organic substances in the water. The ultraviolet oxidizer (TOC-UV) 19 includes, for example, an ultraviolet lamp, and generates ultraviolet rays having a wavelength of around 185 nm. The ultraviolet oxidation device 19 may generate an ultraviolet ray having a wavelength near 254 nm. When the water to be treated is irradiated with ultraviolet rays in the ultraviolet oxidizer 19, the ultraviolet rays decompose the water to be treated to generate OH radicals, which oxidize and decompose organic substances in the water to be treated.

As shown in FIG. 2, the polishers 1a, 1b... 1n are respectively provided on a plurality of branch flow paths 8a, 8b. 2b... 2n are respectively provided on a plurality of

branch channels

9a, 9b. Polishers 1a, 1b... 1n and 2a, 2b... 2n have a mixed bed type ion exchange resin in which a cation exchange resin and an anion exchange resin are mixed, and a small amount of cation components in the water to be treated. And a non-regenerative mixed bed type ion exchange resin apparatus that adsorbs and removes anion components. Here, the number of branch channels 8a, 8b... 8n and the number of

branch channels

9a, 9b... 9n are preferably 2 to 9 (n = 2 to 9), respectively. More preferably, it is more preferably 3-4.

That is, in order to enable continuous operation of the ultrapure water production apparatus 10 even at the time of exchanging the ion exchange resin, it is desirable that the lower limit number of branch flow paths is at least 2 and preferably 3. On the other hand, if the number of branch flow paths exceeds 9, for example, the number of installed devices such as inlet valves, outlet valves, and polishers increases, and the management of these devices becomes complicated. As a result, restrictions on the installation space and the like will increase, and the practicality of operating the ultrapure water production apparatus 10 will be reduced.

In addition, when the number of branch flow paths is larger, when the inlet and outlet valves are opened and closed, fluctuations in the flow rate and pressure in the downstream flow path can be reduced, but the number of branch flow paths is larger. If the flow rate per branch flow path is less than 10 m ³ / h, for example, the size of the polisher (accommodation amount of the ion exchange resin) corresponding to the flow rate becomes too small, and the practicality is lacking. On the other hand, when the flow rate per branch flow path is, for example, more than 100 m ³ / h, the size of the corresponding polisher becomes too large, and there are problems in terms of practicality in consideration of replacement work of the ion exchange resin. It will be.

Examples of the cation exchange resins possessed by the polishers 1a, 1b... 1n and 2a, 2b... 2n include strong acid cation exchange resins and weak acid cation exchange resins. Examples thereof include ion exchange resins and weakly basic anion exchange resins. As a commercial product of mixed bed type ion exchange resin, for example, N-Lite MBSP, MBGP manufactured by Nomura Micro Science Co., Ltd. can be applied.

The inlet valves 3a, 3b ... 3n and the outlet valves 4a, 4b ... 4n are respectively provided before and after the polishers 1a, 1b ... 1n (ion exchange devices) arranged on the branch flow paths 8a, 8b ... 8n. .., 5n and outlet valves 6a, 6b... 6n are respectively provided before and after the polishers 2a, 2b... 2n (ion exchange devices) arranged on the

branch flow paths

9a, 9b. Yes. Here, as shown in FIG. 2, the above-described flow path 7 of the water to be treated includes a circle pump 11, an ultraviolet oxidation device 19, branch flow paths 8 a, 8 b... 8 n, polishers 1 a, 1 b. A circulation flow path that returns to the tank 16 through the booster pump 20, the

branch flow paths

9 a, 9 b, 9 n, the polishers 2 a, 2 b, 2 n, the ultrafiltration membrane device 22, the use point POU and the like is configured.

The degassing device 21 depressurizes the secondary side of the gas permeable membrane, and removes only the dissolved gas in the water flowing through the primary side by passing it to the secondary side, for example, a device such as a degassing membrane device. It is. As the deaerator 21, for example, commercially available products such as 3M X50 and X40 and DIC Separel can be used. The deaeration device 21 removes dissolved oxygen in the water to be treated, and generates treated water having a dissolved oxygen concentration of 1 μg / L or less, for example.

The pressure gauge 23 and the flow meter 24 are provided on the flow path 7 joined on the downstream side of the deaeration device 21, that is, on the downstream side of the plurality of branch flow paths 8a, 8b,. Measure the pressure and flow rate at 7 respectively. The booster pump 20 supplements the water supply by the circle pump 11. The pressure switch 15 monitors an insufficient supply water pressure in the flow path before the booster pump 20.

The ultrafiltration membrane device 2 removes fine particles having a particle diameter of 50 nm or more, preferably 20 nm or more, more preferably 10 nm or more by treating the water to be treated by the polishers 2a, 2b,. Secondary pure water) is obtained. The quality of ultrapure water is, for example, that the number of fine particles having a particle diameter of 50 nm or more is 50 pcs. / L or less, the total organic carbon (TOC) concentration is 1 μg C / L or less, and the resistivity is 18 MΩ · cm or more.

The flow meter 26 is provided on the flow path 7 joined between the ultrafiltration membrane 22 and the use point POU, that is, on the downstream side of the plurality of

branch flow paths

9a, 9b... 9n. The flow rate in the path 7 is measured. The pressure gauge 27 is provided on the flow path 7 between the use point POU and the pressure control valve 29. In the pressure control valve 29, the opening degree of the valve of the main body is automatically controlled so that the pressure measured by the pressure gauge 27 becomes a predetermined constant pressure (pressure of design value).

Moreover, as shown in FIG. 3, the ultrapure water production apparatus 10 of the present embodiment has a control panel 31, and the secondary pure water production unit 18 functions as a controller 32 and an opening changing unit. The controller 33 and the inverter 34 are provided. The control panel 31 supplies electric power to each part of the ultrapure water production apparatus main body including the

controllers

32 and 33 and the inverter 34 and controls these parts in an integrated manner.

The controller 32 acquires the measurement results from the pressure gauge 23 and the flow meter 24. Based on the measurement result obtained by the pressure gauge 23 or the flow meter 24 obtained from the controller 32, the inverter 34 adjusts the circle pump 11 so that the measured pressure or flow rate becomes a predetermined constant pressure or constant flow rate. Controls the operation (number of rotations of the pump drive motor). Further, although not shown in the figure, the controller 32 can also acquire the measurement result by the flow meter 26. The inverter 34 operates the booster pump 20 based on the measurement result obtained by the flow meter 26 obtained from the controller 32 so that the flow rate measured by the flow meter 26 becomes a predetermined constant flow rate (of the pump drive motor). The number of revolutions is also controlled.

Here, the inlet valves 3a, 3b ... 3n and 5a, 5b ... 5n and the outlet valves 4a, 4b ... 4n and 6a, 6b ... 6n provided before and after the polishers 1a, 1b ... 1n and 2a, 2b ... 2n are: A positioner type opening / closing valve (opening adjustment valve) having the above-described positioner 35. This positioner 35 is controlled by a controller (opening changing section) 33, and the above-described inlet valves 3a, 3b,... 3n and outlet valves 4a, 4b,... 4n,

inlet valves

5a, 5b,. It is an electronic opening controller that controls the opening of 6n. Based on an instruction from the controller 33, the positioner 35 moves the position of the actuator for adjusting the opening degree of the inlet valves 3a, 3b,... 3n and the outlet valves 4a, 4b,.

The controller (opening changing unit) 33 sets the opening of the inlet valves 3a, 3b,... 3n, the outlet valves 4a, 4b,... 4n, and the

inlet valves

5a, 5b,. Can be changed over time. In actual operation, the controller (opening changing unit) 33 has a plurality of inlet valves 3a, 3b ... 3n and outlet valves 4a, 4b ... 4n, and

inlet valves

5a, 5b ... 5n and outlet valves 6a, 6b ... The opening degree of any one set of the inlet valve and the outlet valve of 6n is selectively changed. Further, the controller 33 individually sets a time interval for changing the opening degree of any one set of the inlet valve and the outlet valve and a change amount of the opening degree.

That is, the controller 33 accepts an input operation from a user via a predetermined interface, and sets the time interval and the change amount corresponding to the input value. As shown in FIG. 4, in the opening range from 0% at which the valve opening is fully closed to 100% at which the valve opening is fully open, the controller 33 changes the opening. As an amount (increase / decrease amount), for example, an amount such as 1%, 3%, 5%, 10% is set, and for example, as a time interval (increase / decrease period) required for the amount of change in the opening, a time such as 6 seconds or 60 seconds By setting the interval, it is possible to control the gradient of the valve opening. Based on this setting, it is preferable to change the opening degree of the on-off valve from a fully open position to a fully closed position or from a fully closed position to a fully open position at a constant rate.

As shown conceptually in FIG. 4, when such a controller 33 receives a valve open signal or a close signal from the control panel 31, a plurality of inlet valves 3a, 3b... 3n and outlet valves 4a, 4b. Apply a relatively long time, such as 10 to 20 minutes (or more than 20 minutes), for example, to set the opening of any one of the 4n valves. Control that gradually changes from closed (0%) to fully open (100%) or control that gradually changes the valve opening from fully open to fully closed is performed. Moreover, in FIG. 4, although the case where an opening degree is changed continuously is illustrated, you may perform this discontinuously and in steps.

Incidentally, the ion exchange resins of the polishers 1a, 1b... 1n and 2a, 2b... 2n need to be replaced with a period of about one year, for example, with the deterioration of performance over time. When exchanging the ion exchange resin, the inlet and outlet valves before and after the polisher provided on one of the plurality of branch channels 8a, 8b ... 8n and 9a, 9b ... 9n are controlled. After being fully closed by the machine 33, the ion exchange resin of the polisher is replaced. Even in the process of exchanging the ion exchange resin in the polisher, the production of ultrapure water is continuously performed while operating a plurality of other polishers that have not exchanged the ion exchange resin.

Here, in the process of exchanging the ion exchange resin, when the above inlet valve or the like is closed, the pressure loss increases as the flow rate increases in the branch flow path provided with the operating polisher. In the flow path 7 on the downstream side, the pressure and flow rate vary. However, the ultrapure water production apparatus 10 of the present embodiment uses the above-described positioner-type inlet and outlet valves, and a controller (opening changing unit) 33 that is an electronic opening controller. As shown in FIG. 5, it is possible to change the opening of the inlet valve or the like from fully open (Open) to fully closed (Close) over a relatively long time, for example, 10 to 20 minutes. Note that the valve to be applied is not limited to the positioner type, and any other valve can be used as long as the opening can be adjusted over the above time. From the viewpoint of ease of fine adjustment, a positioner type is most preferable.

Therefore, as shown in FIG. 5, since the fluctuations (huntings) A1 and A2 and the huntings A3 and A4 of the inverter output in the flow path 7 on the downstream side of the polisher can be suppressed, secondary pure water The deterioration of the quality of the ultrapure water produced by the production unit 18 is suppressed, and thus ultrapure water in which a desired water quality is ensured can be produced continuously.

On the other hand, FIG. 6 is a block diagram showing the configuration of the control system including the control panel 81 in the secondary pure water production unit provided in the ultrapure water production apparatus of the comparative example. As shown in FIG. 6, the inlet valves 83a, 83b... 83n and the outlet valves 84a, 84b... 84n provided before and after the polisher are conventional air-driven on-off valves. These conventional inlet valves and outlet valves do not have a function of adjusting the opening according to the passage of time, and when a closing signal or an opening signal is transmitted from the control panel 81, a biasing force such as a spring is applied. For example, from fully open to fully closed in a short time such as 3 to 5 seconds. Even if the conventional air-driven inlet and outlet valves are of a type in which orifices (small holes) are arranged in the air passage of the driving air, the transition time from fully open to fully closed is, for example, 10 seconds to 15 Time such as seconds.

The ultrapure water production apparatus of the comparative example to which such conventional inlet valves 83a, 83b,... 83n and outlet valves 84a, 84b,... 84n are applied, for example, in the process of replacing the ion exchange resin of the polisher 1a. When fully closed, the pressure loss increases as the flow rate increases in the branch flow path provided with the active ion exchange device. As a result, as shown in FIG. 7, the flow path 7 on the downstream side of the polisher 1a. Then, the pressure and flow rate fluctuate greatly (hunting B1 and B2 with large pressure and flow rate and hunting B3 and B4 with large inverter output occur).

Specifically, although the fluctuating flow rate and pressure are inverter-controlled by the water supply amount of the circle pump 11 via the inverter 34 according to the measurement values of the flow meter 23 and the pressure gauge 24, the above-described conventional Because of the mechanism of the inlet valve 83a and the like, the inlet valve 83a is suddenly closed in a short time such as 3 seconds to 5 seconds, for example, so that the above inverter control cannot follow the rapid flow rate and pressure fluctuation. Become.

When the flow rate or pressure in the flow path 7 of the water to be treated (secondary pure water) greatly fluctuates, fine particles such as metal colloids from the metal water flow contact surface such as an ultraviolet oxidizer or a pump due to the fluctuation. In some cases, the metal component of the fine particles is gradually ionized and dissolved in water. At this time, the amount of residual ions in the water increases due to the dissolved metal ions, which causes a deterioration in the quality of the ultrapure water (secondary pure water) to be produced.

In addition, when the flow rate or pressure in the flow path of treated water or ultrapure water to be manufactured fluctuates greatly, the fluctuations cause the structural reservoirs such as ultraviolet oxidizers and pumps, pipes and valve members, etc. Substances that deteriorate the water quality, such as fine particles remaining in the reservoir due to the stable water flow, may flow out. At this time, the quality of the produced ultrapure water is deteriorated.

On the other hand, since the ultrapure water production apparatus 10 of the present embodiment can close the on / off valves before and after the polisher over a relatively long time, the water quality is reduced even when the ion exchange resin is replaced. It becomes possible to produce ultrapure water while suppressing. The time taken to close the on-off valve is preferably 5 minutes to 30 minutes, and more preferably 10 to 20 minutes. If it is shorter than 5 minutes, fluctuations in flow rate and pressure cannot be suppressed. Moreover, when it exceeds 30 minutes, since operation takes time too much, practicality will fall. The optimum value for the valve opening / closing time varies depending on the number of branches in the flow path, but even if this is taken into consideration, it can be handled in the above range regardless of the number of branches. It is.

Next, an ultrapure water production method using the ultrapure water production apparatus 10 will be schematically described.

First, ultrapure water is produced by a normal operation using the ultrapure water production apparatus 10 shown in FIG. By continuing the production of this ultrapure water, the performance of the ion exchange resin deteriorates with time as described above, so that it is replaced at an appropriate timing. In the exchange of the ion exchange resin, as shown in FIGS. 2 and 3, first, one of the plurality of branch flow paths 8a, 8b... 8n, 9a, 9b. Here, the case where the polisher to be replaced is, for example, the polisher 1a provided on the branch flow path 8a will be described as an example. Next, the inlet valve 3a and the outlet valve 4a, which are provided before and after the polisher 1a in which the water to be treated is circulated and which are to be replaced, are fully opened, are connected to the controller (opening changing unit) 33. Thus, the opening is gradually changed over a long period of time such as 20 minutes, and then fully closed. Specifically, after the inlet valve 3a is fully closed, the outlet valve 4a is further fully closed. By fully closing the outlet valve 4a, it becomes possible to prevent the backflow of water to be treated to the polisher 1a.

Next, the ion exchange resin of the polisher 1a in which the front and rear inlet valves 3a and the outlet valve 4a are fully closed is replaced with a new ion exchange resin. After exchanging the ion exchange resin, the controller 33 fully opens the outlet valve 4a over a long time such as 20 minutes, and further opens the inlet valve 3a over a long time. Thereby, the polisher 1a can process a to-be-processed water with a new ion exchange resin.
Similarly, the exchange of ion exchange resins in the other polishers 1b to 1n and the polishers 2a to 2n is sequentially performed one by one. Thereby, the ion exchange resin which a polisher has can be replaced | exchanged smoothly, without stopping manufacture operation of ultrapure water.

As described above, in the ultrapure water production apparatus 10 and the ultrapure water production method according to the present embodiment, when the ion exchange resin included in the polisher is replaced, the inlet and outlet valves before and after the polisher are Since it can be closed slowly over time, it is possible to suppress fluctuations in pressure and flow rate in the flow path downstream of the polisher. Therefore, the degradation of the quality of the water to be treated by the secondary pure water production unit 18 is suppressed, and thus ultrapure water with a desired water quality can be continuously produced.

Further, the ultrapure water production apparatus 10 of the present embodiment, for example, provides ultrapure water at the use point POU when the measured value by the pressure switch 15 on the upstream side of the booster pump 20 falls below a prescribed minimum pressure. The control panel 31 has a function of forcibly stopping the supply. However, in the ultrapure water production apparatus 10, as described above, even when the inlet and outlet valves before and after the polishers 1a, 1b,. Therefore, it is possible to reduce the risk of stopping the supply of ultrapure water at the use point POU due to the detection of the drop by the pressure switch 15 on the upstream side of the booster pump 20.

As described above, the present invention has been specifically described with the embodiments. However, the present invention is not limited to these embodiments as they are, and various modifications can be made without departing from the scope of the invention in the implementation stage. For example, some constituent elements may be deleted from all the constituent elements shown in the embodiments, or a plurality of constituent elements disclosed in the above embodiments may be appropriately combined.

1a to 1n, 2a to 2n: Polishers (ion exchange devices), 3a to 3n, 5a to 5n ... Inlet valves (open / close valves), 4a to 4n, 6a to 6n ... Outlet valves (open / close valves), 10 ... Ultrapure water Production apparatus, 11 ... Circle pump, 14 ... Primary pure water production department, 18 ... Secondary pure water production department, 19 ... Ultraviolet oxidizer (TOC-UV), 20 ... Booster pump, 23 ... Pressure gauge (measuring instrument), 24, 26 ... flow meter (measuring instrument), 31 ... control panel, 32 ... controller, 33 ... controller (opening changing section), 34 ... inverter, 35 ... positioner.

Claims

A plurality of branched flow paths that branch the flow path of the water to be treated and merge downstream;
A plurality of ion exchange devices each provided on the plurality of branch channels, each having an ion exchange resin;
A plurality of on-off valves respectively provided before and after each of the ion exchange devices on each of the branch flow paths;
An opening degree changing unit for changing the opening degree of the on-off valve according to the elapse of a set time;
An ultrapure water production apparatus.
A primary pure water production section for producing primary pure water by removing organic components and ionic components in the pretreated water obtained by pretreating raw water;
A secondary pure water production section for producing secondary pure water to remove ultrapure water by removing impurities in the produced primary pure water;
With
The plurality of branch channels, the plurality of ion exchange devices, and the plurality of on-off valves are provided in the secondary pure water production unit,
The ultrapure water production apparatus according to claim 1.
The opening degree changing unit individually sets a time interval for changing the opening degree and a change amount of the opening degree.
The ultrapure water production apparatus according to claim 1 or 2.
The opening degree changing unit selectively changes the opening degree of any one of the plurality of on-off valves;
The ultrapure water production apparatus according to any one of claims 1 to 3.
The on-off valve is a positioner type on-off valve.
The ultrapure water production apparatus according to any one of claims 1 to 4.
A pump provided on a flow path before branching upstream of the plurality of branch flow paths;
A measuring instrument that is provided on a flow path merged on the downstream side of the plurality of branch flow paths, and measures a flow rate or pressure in the merged flow path;
Based on the measurement result by the measuring instrument, an inverter for controlling the operation of the pump;
The ultrapure water production apparatus according to any one of claims 1 to 5.
A plurality of branch flow paths that once branch the flow path of the water to be treated and merge on the downstream side, a plurality of ion exchange devices that are respectively provided on the plurality of branch flow paths and each have an ion exchange resin, An ultra-pure comprising a plurality of on-off valves provided before and after each of the ion exchange devices on the branch flow path, and an opening degree changing unit that changes the opening degree of the on-off valve according to the passage of a set time. An ultrapure water production method using a water production apparatus,
The opening / closing valves before and after the ion exchange device provided on one branch channel among the plurality of branch channels through which the treated water circulates are each fully closed by the opening degree change unit,
Replacing the ion exchange resin of the ion exchange apparatus in which the front and rear on-off valves are fully closed;
After the exchange of the ion exchange resin, a step of fully opening the front and rear on-off valves that are fully closed by the opening changing unit,
A method for producing ultrapure water.