Method for starting up and cleaning water treatment equipment

Abstract

To early supply ultrapure water of high water quality with a simple procedure.SOLUTION: A method for starting up a water treatment device includes the steps of: obtaining an amount of an impurity included in water supplied to a position of attachment of a UF 70 of the water treatment device; and starting water passage to the UF 70 when the obtained amount is less than a reference value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for starting up and cleaning a water treatment device. [Background technology]

[0002] Ultrapure water, in which impurities have been removed using advanced technology, is generally produced by sequentially treating raw water (river water, groundwater, industrial water, etc.) in a pretreatment system, a primary pure water production system, and a secondary pure water production system (subsystem). The ultrapure water produced is highly pure water. This type of ultrapure water is used for various purposes, such as the cleaning process for cleaning semiconductor and liquid crystal devices in the manufacturing process. Therefore, metals contained in ultrapure water are a direct cause of reducing the yield rate of devices.

[0003] Therefore, in order to prevent metal contamination (adhesion) of the ultrafiltration membrane device in an ultrapure water production facility equipped with an ultrafiltration membrane device, a technology has been devised in which, when the ultrapure water production facility is started up, piping is arranged so that the water supplied to the ultrafiltration membrane device passes through a microfiltration membrane device, and water is passed through the piping for a predetermined period of time to supply water treated by the microfiltration membrane device to the ultrafiltration membrane device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-81957 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned technology, since it is necessary to provide a microfiltration membrane device, the scale of the entire system becomes large and the operation method becomes complicated. In addition, since the period for passing water through the piping is determined based on time, if water is supplied to the ultrafiltration membrane device after a certain time has passed without passing the water through the piping (i.e., without being treated by the microfiltration membrane device), it is not possible to accurately grasp the level of impurities contained in the water supplied to the ultrafiltration membrane device, and there is a risk of metal contamination (adhesion) of the ultrafiltration membrane device. In that case, the quality of the ultrapure water deteriorates, and there is a problem that it takes a long time before high-quality ultrapure water is supplied.

[0006] An object of the present invention is to provide a method for starting up and cleaning a water treatment system, which is capable of quickly supplying high-quality ultrapure water using simple procedures. [Means for solving the problem]

[0007] The start-up method of the water treatment device of the present invention includes the steps of: A method for starting up a water treatment device, comprising: Obtaining the amount of impurities contained in the water supplied to a position where the ultrafiltration membrane device of the water treatment device is installed; If the acquired amount is less than the reference value, a step of starting to pass water through the ultrafiltration membrane device is performed.

[0008] The cleaning method for a water treatment device of the present invention includes the steps of: A cleaning method for cleaning a water treatment device, comprising the steps of: A step of sterilizing a system constituting the water treatment device using hydrogen peroxide; a step of forcing the hydrogen peroxide out of the system using water supplied from a primary pure water production facility; After the hydrogen peroxide is pushed out, a step of filling the ion exchange resin constituting the water treatment device; After the ion exchange resin is filled, a step of attaching an ultrafiltration membrane device constituting the water treatment device is carried out. Effect of the Invention

[0009] In the present invention, high-quality ultrapure water can be quickly supplied using a simple procedure. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a diagram illustrating an example of a basic configuration of a water treatment device during operation. [Diagram 2] FIG. 2 is a diagram showing an example of the configuration of the water treatment device shown in FIG. 1 during start-up according to the present invention. [Diagram 3] FIG. 2 is a diagram showing an example of the configuration after the hydrogen peroxide in the equipment components is pushed out and then the CP shown in FIG. 1 is filled in. [Figure 4] FIG. 13 is a diagram showing an example of the configuration after MD and UF are attached to a water distribution line. [Diagram 5] FIG. 2 is a diagram showing a configuration of the water treatment device shown in FIG. 1 in Comparative Example 1 at the time of start-up. [Figure 6] FIG. 2 is a diagram showing an example of the configuration after the hydrogen peroxide in the equipment components is pushed out and then the CP shown in FIG. 1 is filled in. [Figure 7] 1. FIG. 4 is a diagram showing a configuration of the water treatment device shown in FIG. 1 in Comparative Example 2 at the time of start-up. [Figure 8] FIG. 2 is a diagram showing an example of the configuration after the hydrogen peroxide in the equipment components is pushed out and then the CP shown in FIG. 1 is filled in. [Figure 9] FIG. 13 is a diagram showing an example of the configuration after MD and UF are attached to a water distribution line. [Figure 10] 1 is a graph showing the relationship between the start-up time of a water treatment device and the iron concentration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 is a diagram showing an example of a basic configuration of a water treatment device during operation. As shown in FIG. 1, the basic configuration of the water treatment device during operation includes a tank 10, a pump 20, an HE 30, a UVox 40, a CP 50, an MD 60, a UF 70, and a control valve 80 connected (arranged) in series. The tank 10 is a tank in which primary pure water produced in a primary pure water production facility is stored. The pump 20 pumps up the primary pure water stored in the tank 10 and supplies it to the HE 30. The HE 30 is a heat exchanger. The UVox 40 is an ultraviolet oxidation device. The CP (cartridge polisher) 50 is a non-regenerative ion exchange resin (ion exchange device). The MD 60 is a membrane degassing device that removes dissolved oxygen. The UF 70 is an ultrafiltration membrane device. In addition, when the water treatment device shown in FIG. 1 is started up, most of the treated water treated by the UF 70 is returned to the tank 10 and circulated. A control valve 80 provided after the UF 70 is used to circulate this treated water. For example, in accordance with a control signal transmitted from an externally connected control device, the control valve 80 opens and closes so as to supply water from the UF 70 to either a point for cleaning semiconductors or the like or to the tank 10. These devices (components) may be those used in general water treatment systems. Note that the configuration may also be such that the MD60 shown in FIG. 1 is not attached to the water distribution line. The same applies to the following explanation. Note that the water treatment device is, for example, a secondary pure water production facility.

[0013] A recent method for starting up water treatment equipment is to sterilize the system with hydrogen peroxide, push out the hydrogen peroxide with water supplied from the primary pure water production facility, and then fill the ion exchange resin. If this method is applied to a water treatment equipment as shown in Figure 1, hydrogen peroxide cleaning will be performed with the UF70 installed. If hydrogen peroxide is pushed out with water supplied from the primary pure water production facility while the UF70 is installed, metal impurities will adhere to the UF70 and then be constantly eluted from the UF70. With the rapid increase in integration and miniaturization of semiconductor devices in recent years, the concentration control value of metal impurities is becoming increasingly higher. Therefore, the constant elution of metal impurities must be avoided.

[0014] Therefore, in the present invention, the steps described below are performed as a start-up method for a water treatment device. FIG. 2 is a diagram showing an example of the configuration of the present invention when the water treatment device shown in FIG. 1 is started up. As shown in FIG. 2, the configuration shown in FIG. 1 is in a state where CP50, MD60, and UF70 are not attached. In this state, the pump 20 pumps up ultrapure water stored in the tank 10 to wash the components of the water treatment device including piping, pumps, etc. (hereinafter referred to as equipment components). Next, the equipment components are immersed in hydrogen peroxide for sterilization. The concentration of hydrogen peroxide used for sterilization is, for example, 1%. After sterilization of the equipment components, the pump 20 pumps up ultrapure water stored in the tank 10, and the ultrapure water is used to push out the hydrogen peroxide.

[0015] After that, the CP50 is filled and water is passed through. FIG. 3 is a diagram showing an example of the configuration after the CP50 shown in FIG. 1 is filled after pushing out the hydrogen peroxide in the equipment components. As shown in FIG. 3, the CP50, which is an ion exchange resin, is filled and water is passed through. Immediately after the water passage is started, the amount of impurities contained in the water supplied to the position where the UF70 is attached is obtained. Here, for example, the concentration of metal impurities is measured. As an analysis method for obtaining the value of this concentration, a concentration method using an ion adsorbent is desirable. The concentration method using an ion adsorbent is a method in which the target ultrapure water is passed through the ion adsorbent for a predetermined time, the impurities adsorbed on the ion adsorbent are eluted with an eluent, the concentration of the impurities contained in the eluent from which the impurities have been eluted is measured, and the concentration of the impurities contained in the eluent from which the impurities have been eluted is calculated based on the measured concentration. The ion adsorbent used for this analysis is provided, for example, on a branch line that branches off from the outlet of the CP50, that is, between the position where the CP50 is attached and the position where the UF70 is attached, and the ion adsorbent is provided on the branch line. The valve installed at the branch point is controlled to control the flow of water into the branch line, and the ion adsorbent concentrates metal impurities contained in the water flowing into the branch line, and the metal impurities concentrated in the ion adsorbent are analyzed. This ion adsorbent has an ion removal or ion adsorption function (for example, an ion adsorption membrane or a monolithic organic porous material, an ion exchange resin). The target to be removed or adsorbed by the ion adsorbent is ionic metal impurities. The ion adsorbent also adsorbs fine particles by electrostatic effects. In this embodiment, the functional group of the ion adsorbent is a cation, an anion exchange group, or a chelate compound. The ion exchanger is preferably a monolithic ion exchanger, and examples thereof include those described in International Publication No. 2019-221186.

[0016] The standard value of the concentration of metal impurities at the time of start-up is not particularly limited, but is preferably 1 ng / L or less, and more preferably 0.1 ng / L or less. The same applies to the following explanation.

[0017] If the amount of impurities (e.g., the concentration of metal impurities) obtained as a result of the analysis is less than a predetermined standard value, the UF70 is installed. At this time, if the installation of the MD60 is necessary for the configuration of the equipment to be used, the MD60 and the UF70 are installed. FIG. 4 is a diagram showing an example of the configuration after the MD60 and the UF70 are installed in the water distribution line. The configuration shown in FIG. 4 is the basic configuration shown in FIG. 1, and after this configuration is achieved, water is passed through and operation is started. The UF70 to be installed may be one that is pre-filled with hydrogen peroxide. The UF70 to be installed is one in which an ultrafiltration membrane is housed in a container, and this container is installed in the water distribution line. Also, the container in which the ultrafiltration membrane is housed may be pre-filled with hydrogen peroxide. It is preferable not to use a metal-based material in the stage following the CP50, and even if a metal-based material is used, the condition is that the concentration of metal impurities is less than the standard value by cleaning.

[0018] The above steps may be controlled by, for example, a control device (not shown). In that case, the control device judges the timing and feasibility of attaching each component. For example, the control device may measure the elapsed time from the start of pushing out hydrogen peroxide and judge that it is the timing to start filling CP50 when the measured elapsed time reaches a predetermined threshold value. Also, a path that does not pass through UF70 may be provided after CP50, in addition to the path that passes through UF70, and the control device may select a path that does not pass through UF70 as the path through which ultrapure water flows until the step of acquiring the amount of impurities described above (measuring the concentration of metal impurities), and when the acquired amount of impurities (measured concentration of metal impurities) is less than a predetermined reference value, control to switch to the path that passes through UF70. In this case, a switching valve may be provided at the branch point of these paths, and the control device may control the valve. Also, a valve for controlling the inflow of ultrapure water into UF70 may be provided in front of UF70, and the control device may control the valve to control the inflow of ultrapure water into UF70. Also, even after UF70 is installed, the control valve 80 may be controlled based on the amount of impurities contained in the water at the above-mentioned analysis position or the outlet of UF70. When performing maintenance by performing such control, if the amount of impurities obtained is less than a reference value, the control valve 80 is controlled so that the water is supplied to a point for cleaning semiconductors, etc. Also, if the amount of impurities obtained is equal to or greater than a reference value, the control valve 80 is controlled so that the water is returned to the upstream tank 10 for circulation. This control may be performed by the control device.

[0019] By carrying out the above-mentioned steps when starting up the water treatment device, water with a low concentration of metal impurities can be obtained more quickly than before. The results of a comparison with a conventional configuration are shown below. In the following explanation, two comparative examples using conventional configurations are presented for comparison with the configuration of the present invention. Comparative Example 1

[0020] Fig. 5 is a diagram showing the configuration of Comparative Example 1 at the start-up of the water treatment device shown in Fig. 1. As shown in Fig. 5, the basic configuration shown in Fig. 1 is in a state where CP50 is not attached. In this state, the pump 20 pumps up ultrapure water stored in the tank 10 to wash the equipment components. Next, the equipment components are immersed in hydrogen peroxide for sterilization. The concentration of hydrogen peroxide used for sterilization is, for example, 1%. After the equipment components are sterilized, the pump 20 pumps up the ultrapure water stored in the tank 10, and the ultrapure water is used to push out the hydrogen peroxide.

[0021] After that, CP50 is filled and water is passed through. Figure 6 is a diagram showing an example of the configuration after the hydrogen peroxide in the equipment components is pushed out and the CP50 shown in Figure 1 is filled. As shown in Figure 6, CP50, which is an ion exchange resin, is filled and water is passed through. After water is passed through for a predetermined period, operation begins. Comparative Example 2

[0022] FIG. 7 is a diagram showing the configuration of Comparative Example 2 at the start-up of the water treatment device shown in FIG. 7, the configuration shown in FIG. 1 is in a state where CP50, MD60, and UF70 are not attached. In this state, the pump 20 pumps up ultrapure water stored in the tank 10 to wash the equipment components. Then, the equipment components are immersed in hydrogen peroxide for sterilization. The concentration of hydrogen peroxide used for sterilization is, for example, 1%. After the equipment components are sterilized, the pump 20 pumps up the ultrapure water stored in the tank 10, and the ultrapure water is used to push out the hydrogen peroxide.

[0023] Thereafter, CP50 is filled and water is passed through. FIG. 8 is a diagram showing an example of the configuration after the hydrogen peroxide in the equipment components is pushed out and the CP50 shown in FIG. 1 is filled. As shown in FIG. 8, CP50, which is an ion exchange resin, is filled and water is passed through. Thereafter, the resistivity value of the water supplied to the position where the UF70 is attached is measured as the concentration of metal impurities. A control device (not shown) judges whether the value measured by the measuring device is less than a predetermined reference value. Here, the reference value is, for example, 18.2 MΩ·cm.

[0024] If the value measured by the measuring device is less than a predetermined reference value, the UF70 is installed. At this time, if the equipment being used includes the MD60, the MD60 and the UF70 are installed. FIG. 9 is a diagram showing an example of the configuration after the MD60 and the UF70 are installed in the water distribution line. The configuration shown in FIG. 9 is the basic configuration shown in FIG. 1, and after this configuration is achieved, water is passed through and operation begins.

[0025] FIG. 10 is a graph showing the relationship between the start-up time and the iron concentration contained in the water flowing out from the rear stage of UF70 in the start-up method of the present invention described with reference to FIGS. 2 to 4, the start-up method of Comparative Example 1 described with reference to FIGS. 5 and 6, and the start-up method of Comparative Example 2 described with reference to FIGS. 7 to 9. The relationship shown in FIG. 10 is a relationship obtained by an experiment. In the graph shown in FIG. 10, the start-up time "0" is the time when water starts to flow in the configuration shown in FIG. 3 in the present invention (Example), the time when water starts to flow in the configuration shown in FIG. 6 in Comparative Example 1, and the time when water starts to flow in the configuration shown in FIG. 8 in Comparative Example 2. Referring to the results of the experiment shown in FIG. 10, it can be seen that the water treatment device has a lower concentration more quickly when the start-up method of Comparative Example 2 is applied than when the start-up method of Comparative Example 1 is applied. Furthermore, it can be seen that the water treatment device has a lower concentration more quickly when the start-up method of the present invention (Example) is applied than when the start-up method of Comparative Example 2 is applied. It can also be seen that the concentration of iron impurities is high and steadily elutes in Comparative Example 1 and Comparative Example 2. On the other hand, in the present invention (Example), the elution of iron from UF 70 is greatly suppressed. Also, in Comparative Example 2, the timing of installation of UF 70 is determined based on the results of resistivity confirmation, but since the elution of iron from UF 70 is suppressed in the present invention (Example), it is understood that in Comparative Example 2, trace amounts of metal that cannot be detected by resistivity confirmation remain attached to UF 70.

[0026] In this way, when starting up a water treatment system equipped with an ultrafiltration membrane device, first remove the ultrafiltration membrane device and sterilize the equipment components with hydrogen peroxide, then pass water through the system, and when the concentration of metal impurities in the water at the location where the ultrafiltration membrane device is installed falls below the standard value, install the ultrafiltration membrane device and operate the system. This makes it possible to prevent contamination of the ultrafiltration membrane device by metal impurities and reduce the elution of metal impurities into subsequent stages.

[0027] The above-mentioned steps may be performed not only when the water treatment device is started up, but also after maintenance of the water treatment device is performed. That is, the supply of water to the ultrafiltration membrane device may be stopped at a predetermined timing for maintenance or other work, and after the maintenance work is completed, the state shown in Fig. 2 may be restored and the same steps may be performed.

[0028] Regarding cleaning of the water treatment device, the above-mentioned steps can be carried out at the time of start-up of the water treatment device, thereby cleaning the water treatment device. [Explanation of symbols]

[0029] 10. Tank 20 Pump 30 HE 40 UVox 50 CP 60 MD 70 UF 80 Control valve

Claims

1. A method for starting up a water treatment device, comprising: Obtaining the amount of impurities contained in the water supplied to the position where the ultrafiltration membrane device of the water treatment device is installed by using concentration analysis using an ion adsorbent; and if the acquired amount is less than a reference value, starting the flow of water through the ultrafiltration membrane device.

2. The start-up method according to claim 1, The step of acquiring the amount of impurities is carried out before the ultrafiltration membrane device is installed in the water treatment device, If the acquired amount is less than the reference value, the start-up method includes starting to pass water through the ultrafiltration membrane device after the ultrafiltration membrane device is installed.

3. The start-up method according to claim 1, The step of acquiring the amount of impurities is performed after a predetermined period of time has elapsed since the ultrafiltration membrane device is attached to the water treatment device, water is supplied to the ultrafiltration membrane device to start production of ultrapure water, and then the supply of water to the attached ultrafiltration membrane device is stopped; The start-up method includes a step of resuming the supply of water to the ultrafiltration membrane device when the acquired amount is less than the reference value.

4. The start-up method according to claim 1, The ion adsorbent is a monolithic organic porous material.

5. The start-up method according to any one of claims 1 to 4, A step of installing an ion exchange device in a stage upstream of a position where the ultrafiltration membrane device is installed in the water treatment device is performed; The step of acquiring the amount of impurities is performed on the water treated in the ion exchange device immediately after the water starts to pass through the ion exchange device.

6. The start-up method according to any one of claims 1 to 5, The reference value is 1 ng / L or less.

7. The start-up method according to any one of claims 1 to 6, The water treatment device is a secondary pure water production facility.

8. A cleaning method for cleaning a water treatment device, comprising the steps of: A step of sterilizing a system constituting the water treatment device using hydrogen peroxide; a step of forcing the hydrogen peroxide out of the system using water supplied from a primary pure water production facility; After the hydrogen peroxide is pushed out, a step of filling the ion exchange resin constituting the water treatment device; After filling the ion exchange resin, a step of installing an ultrafiltration membrane device constituting the water treatment device; After installing the ultrafiltration membrane device, a step of acquiring the amount of impurities contained in the water supplied to the position where the ultrafiltration membrane device of the water treatment device is installed by using a concentration analysis using an ion adsorbent; and if the acquired amount is less than the reference value, starting the flow of water through the ultrafiltration membrane device.

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