TW202413283A - Operation management method and operation management system for ultrapure water production device - Google Patents

Abstract

An operation management method for ultrapure water production device 1 having an ion exchange device 6 comprises a step of quantifying the metal components contained in the treated water from the ion exchange device 6 over time; a step of obtaining the change over time in the concentration of the metal components based on the results of quantification over time; and a step of evaluating the performance of the ion exchange resin filled inside the ion exchange device 6 based on the acquired change over time.

Description

Operation management method and operation management system of ultrapure water production device

The present invention relates to an operation management method and an operation management system of an ultrapure water production device.

In the manufacturing process of semiconductor devices or liquid crystal devices, ultrapure water with a high degree of impurities removed is used in various applications such as the rinsing step. The metal components contained in ultrapure water have a great impact on the characteristics of the device even in trace amounts, so the concentration of the metal components must be strictly managed. In recent years, with the rapid integration and miniaturization of semiconductor devices, the requirements for the metal concentration in ultrapure water have become increasingly stringent, requiring ultrapure water with a metal concentration of pg/L.

Ultrapure water is generally produced by treating raw water (river water, groundwater, industrial water, etc.) in sequence with a pre-treatment system, a primary pure water system, and a secondary pure water system (subsystem), but the ion exchange device plays a major role in managing the metal concentration in ultrapure water. The ion exchange device is filled with ion exchange resin and is mostly installed at the most downstream side of the subsystem or as the next to the superfiltration membrane device installed at the most downstream side of the subsystem. It is known that metal components are eluted from the pipes or pumps used in the production process of ultrapure water, but the ion exchange device can suppress the influence of the metal components on the water quality of ultrapure water even if metal components are eluted on its upstream side.

In an ultrapure water production device having such an ion exchange device, since the reduction in the performance of the ion exchange resin is directly related to the deterioration of the water quality of the ultrapure water, it is important to accurately evaluate the performance of the ion exchange resin and judge whether the ion exchange resin needs to be replaced based on the evaluation. Patent document 1 describes a method of performing a composition analysis of adsorbed substances adsorbed on the ion exchange resin and then judging the replacement period of the ion exchange resin based on the analysis results. [Prior art document] [Patent document]

Patent document 1: Japanese Patent Application Publication No. 2016-118408

[The problem that the invention wants to solve]

In the method described in Patent Document 1, it is actually necessary to take a portion of the loaded ion exchange resin from the ion exchange device as a sample in order to analyze the composition of the adsorbed substance. Therefore, the supply of the treated water must be stopped and the operation of the ion exchange device must be stopped. In addition, because the ion exchange resin is taken, there is a risk of device contamination and the quality of the treated water may deteriorate.

Therefore, the purpose of the present invention is to provide an operation management method and operation management system for an ultrapure water production device that can appropriately judge whether the ion exchange resin needs to be replaced due to the deterioration of its performance while continuing to operate stably. [Means for solving the problem]

In order to achieve the above-mentioned purpose, the operation management method of the ultrapure water production device of the present invention is an operation management method of the ultrapure water production device having an ion exchange device, which includes the following steps: quantitatively measuring the metal components contained in the treated water from the ion exchange device over time; obtaining the change of the concentration of the metal components over time based on the result of the quantitative measurement over time; and evaluating the performance of the ion exchange resin filled in the ion exchange device based on the obtained change over time.

The operation management system of the ultrapure water production device of the present invention is an operation management system of the ultrapure water production device having an ion exchange device, and has: an evaluation device, which obtains the change of the concentration of the metal component over time from the quantitative value of the metal component contained in the treated water from the ion exchange device, and evaluates the performance of the ion exchange resin filled in the ion exchange device based on the obtained change over time.

According to the operation management method and operation management system of such an ultrapure water production device, by monitoring the actual water quality changes of the treated water from the ion exchange device, the performance of the ion exchange resin can be accurately evaluated. As a result, it is possible to stably produce ultrapure water of good water quality while grasping the appropriate replacement period of the ion exchange resin. [Effect of the invention]

As described above, according to the present invention, it is possible to appropriately judge whether exchange is necessary due to degradation of the performance of the ion exchange resin while continuing stable operation.

Hereinafter, the embodiment of the present invention will be described with reference to the drawings. Although an ultrapure water production device is exemplified in this specification, the device to which the operation management method of the present invention is applicable is not limited thereto, and may be a pure water device.

Fig. 1 is a schematic diagram showing the structure of an ultrapure water production device according to an embodiment of the present invention. In addition, the structure of the ultrapure water production device shown in the figure is only an example and does not limit the present invention.

The ultrapure water production device 1 has: a primary pure water tank 2, a pump 3, a heat exchanger 4, an ultraviolet oxidation device 5, an ion exchange device 6 and an ultrafiltration (UF) membrane device 7. The primary pure water tank 2, the pump 3, the heat exchanger 4, the ultraviolet oxidation device 5, the ion exchange device 6 and the UF membrane device 7 are connected by a circulation pipeline L1 to form a secondary pure water system (subsystem), and sequentially process the primary pure water produced by the primary pure water system (not shown) to produce ultrapure water and supply the ultrapure water to the use point 8.

The treated water (primary pure water) stored in the primary pure water tank 2 is sent out by the pump 3 and supplied to the heat exchanger 4. The treated water after temperature adjustment by the heat exchanger 4 is supplied to the ultraviolet oxidation device 5 for irradiation with ultraviolet rays. In this way, the total organic carbon (TOC) in the treated water can be decomposed. Then, the treated water is treated by ion exchange in the ion exchange device 6 to remove metals and the like, and the fine particles are removed in the UF membrane device 7. A portion of the ultrapure water produced in this way can be supplied to the use point 8 and the remaining portion can be sent back to the primary pure water tank 2. Primary pure water can be supplied to the primary pure water tank 2 by the primary pure water system (not shown) as needed. The primary pure water tank 2, pump 3, heat exchanger 4, ultraviolet oxidation device 5, ion exchange device 6 and UF membrane device 7 can be used as the subsystem of the ultrapure water production device. For example, the ion exchange device 6 can be a non-regenerative mixed bed ion exchange device (cassette purifier) filled with cation exchange resin and anion exchange resin in a mixed bed manner.

When the ultrapure water produced in the ultrapure water production device 1 is used to rinse semiconductor devices and liquid crystal displays, etc., the metal concentration in the ultrapure water is required to be strictly managed as described above. The metal concentration at this time depends largely on the performance of the ion exchange resin filled in the ion exchange device 6. That is, when the performance of the ion exchange resin decreases, the metal components contained in the treated water are not removed by the ion exchange device 6 and leak into the ultrapure water, so the level that meets the water quality requirements of the ultrapure water is not reached. Therefore, in terms of the operation management for supplying ultrapure water of stable water quality to the use point 8, it is necessary to correctly evaluate the performance of the ion exchange resin and judge whether the ion exchange resin needs to be replaced based on the evaluation. In order to evaluate the performance of the ion exchange resin, the present embodiment morphologically analyzes the metal concentration in the treated water from the ion exchange device 6. Therefore, a sampling device 10 for sampling the metal components contained in the treated water from the ion exchange device 6 is provided in the ultrapure water production device 1.

The sampling device 10 is composed of a sampling line L2 and a concentration column 11 disposed in the sampling line L2. The sampling line L2 is connected to the circulation line L1 between the ion exchange device 6 and the UF membrane device 7 through a valve V1. The concentration column 11 captures the metal components in the sample water (processed water from the ion exchange device 6) supplied through the sampling line L2 to concentrate the metal components and has a porous ion exchanger as a capturing member inside. As the porous ion exchanger, for example, an ion adsorption membrane (particularly a porous membrane having cation exchange capability) can be used, but from the viewpoint of being able to pass water at a higher spatial velocity and shortening the time required for concentration, it is preferable to use a monolithic organic porous ion exchanger. In addition, at least the liquid contacting portion of the sampling device 10 is preferably made of non-metal, such as synthetic resin, and particularly preferably made of fluororesin such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) or polypropylene (PP).

Here, a method for analyzing the metal concentration in the treated water from the ion exchange device 6 using the above-mentioned sampling device 10 and a method for evaluating the performance of the ion exchange resin based on the analysis result are described.

First, open valve V1, supply a portion of the treated water from the ion exchange device 6 as sample water to the sampling line L2 and pass the water to the concentration column (container) 11. In this way, the porous ion exchanger filled in the concentration column 11 captures the metal components in the sample water to concentrate it. The water flow time (concentration time) at this time depends on the amount of water flowing through the concentration column 11, but as long as the metal components to be analyzed are concentrated to a degree that can be quantified with sufficient accuracy, there is no special restriction, such as several days. Then, after the predetermined water flow time, close valve V1 and stop the water flow to the concentration column 11. Next, the concentration column 11 is removed from the sampling line L2 to recover the porous ion exchanger filled inside.

Next, the metal components captured by the recovered porous ion exchanger are eluted into an elution solution (e.g., nitric acid diluted to a predetermined concentration). Next, the metal components in the elution solution are quantified and the metal concentration in the sample water is calculated from the obtained metal amount (quantitative value). For the quantitative method of the metal components, for example, an inductively coupled plasma mass spectrometer (ICP-MS) can be used, and the metal concentration in the sample water can be calculated by dividing the obtained metal amount by the concentration ratio of the elution solution.

The types of metal components to be analyzed are not particularly limited, and at least one of Na, K, Ca, Mg, Fe, Cu, Al, Zn, Ni, Cr and Pb can be used as the analysis object. Among them, Na (sodium) is preferably used as the analysis object. This is because compared with other metal components, the content of sodium in the treated water supplied to the ion exchange device 6 is high (but it also depends on the water quality of the raw water or the structure of the primary pure water system) and it is difficult to be adsorbed by the cation exchange resin in the ion exchange device 6 (the selectivity is relatively low). That is, when the performance of the ion exchange resin decreases, sodium is not adsorbed before other metal components, resulting in an increase in the sodium concentration in the treated water. Therefore, by using sodium as the analysis object, it is possible to predict in advance that other metal components will leak from the ion exchange device 6, so that ultrapure water of good water quality can be stably supplied to the use point 8. In addition, the metal component here means both metal ions and metal particles (microparticles).

Such quantitative analysis is repeated over time (preferably periodically), and the change of metal concentration in the sample water over time is obtained based on the result. That is, after removing the concentration column 11 from the sampling line L2 to analyze the captured metal components, another concentration column 11 is installed in the sampling line L2. The metal components in the sample water are captured and analyzed again using the concentration column 11. Then, the calculated metal concentration is plotted against the water flow time of the ion exchange device 6 at the time of removing the concentration column 11 (the time that has passed since the ion exchange resin was started), and the change of metal concentration in the sample water over time is obtained. Then, the performance of the ion exchange resin filled in the ion exchange device 6 is evaluated based on the changes with time thus obtained. A specific evaluation method is described below with reference to Fig. 2. Fig. 2 is a graph showing an example of changes with time in the metal concentration in the sample water.

When the metal concentration _Ci is obtained at time _ti , the change amount ΔC/Δt of the metal concentration per unit time is calculated based on the time ti _-1 at which the metal component was obtained before and the metal concentration Ci _-1 at this time. Here, Δt is the time difference between time _ti-1 and time _ti (= _ti - _ti-1 ) and ΔC is the concentration difference between metal concentration Ci _-1 and metal concentration _Ci (= _Ci - _Ci-1 ). Next, it is determined whether the calculated change amount ΔC/Δt is greater than a preset predetermined value. If it is greater than the predetermined value, it is determined that the metal component to be analyzed is not removed by the ion exchange device 6 and leaks out, and therefore it is determined that the performance of the ion exchange resin in the ion exchange device 6 is degraded. In addition, the preset value at this time is not particularly limited and can be preset based on experimental verification, but it is preferably set according to the error in the above-mentioned quantitative analysis. That is, when the quantitative error is large, the change in metal concentration caused by the reduction in the performance of the ion exchange resin is masked by the error and may not be correctly detected. Therefore, the larger the quantitative error, the larger the preset value should be.

Thus, according to the present embodiment, by monitoring the actual water quality changes (concentration changes of the metal components to be analyzed) of the treated water from the ion exchange device 6, the performance of the ion exchange resin can be accurately evaluated. As a result, it is possible to stably produce ultrapure water of good water quality while mastering the appropriate replacement period of the ion exchange resin. In addition, in order to evaluate the performance of the ion exchange resin, it is also considered, for example, to perform the above-mentioned quantitative analysis once and compare the obtained quantitative value (metal concentration) with the predetermined critical value each time. However, such a method has already supplied ultrapure water with deteriorated water quality to the point of use at the time when it is confirmed that the quantitative value exceeds the critical value and thus the performance of the ion exchange resin has decreased. Therefore, from the viewpoint of being able to predict the performance of the ion exchange resin before it deteriorates, it is also preferable to perform the above-mentioned quantitative analysis over time and monitor the metal concentration in the treated water from the ion exchange device 6 over time.

The manager of the ultrapure water production device 1 can perform the above-mentioned performance evaluation of the ion exchange resin, but the operation management system for operating the ultrapure water production device 1 can also be implemented. That is, the control device (evaluation device) 20 of the operation management system can obtain the change of the metal concentration in the sample water over time from the input data (the quantitative value of the metal component or the metal concentration in the sample water calculated from the quantitative value) input by the manager of the ultrapure water production device 1, and evaluate the performance of the ion exchange resin according to the above-mentioned method based on the obtained change over time. In addition, at this time, when the control device 20 determines that the performance of the ion exchange resin has decreased, it is appropriate to issue an alarm to the manager of the ultrapure water production device 1 to urge the replacement of the ion exchange resin.

On the other hand, the ion exchange resin performance evaluation including the quantitative analysis after the concentration column 11 is removed from the ultrapure water production device 1 is often performed at a location far away from the site where the ultrapure water production device 1 is installed. Even in such a case, when it is determined that the performance of the ion exchange resin has deteriorated at a location far away from the site, in order to be able to respond more quickly on site, it is advisable to issue an alarm to the on-site operator (user) to urge the replacement of the ion exchange resin. In addition, when the manufacturing or sales company of the ion exchange resin performs the above-mentioned quantitative analysis and the performance evaluation based on the quantitative analysis, it can provide (sell) a brand new ion exchange resin to the user of the ultrapure water production device 1 after issuing the alarm.

In order to more accurately evaluate the performance of ion exchange resin, it is advisable to perform the above quantitative analysis at the shortest possible interval and collect more time series data. However, in order to improve the quantitative accuracy, it is also necessary to use the concentration column 11 to fully concentrate the metal components in the sample water, and the water flow for concentration requires time. Therefore, there is a limit to shortening the time interval of time series data. Therefore, the sampling line L2 can be branched or multiple sampling lines L2 can be set and concentration columns 11 can be set in each of the sampling lines. Then, the above series of steps of capturing and quantifying the metal components can be repeated in parallel for each concentration column 11 while staggering the time. Therefore, compared with the case where a series of steps are repeated using a single concentration column 11, the time interval for obtaining the metal concentration can be shortened.

In addition, as for the method of concentrating the metal components in the sample water, in addition to the method of using the above-mentioned porous ion exchanger, a method of heating the sample water for concentration can also be considered. However, in this method, the concentration rate obtained by heating is limited, and a large amount of sample water needs to be taken in order to obtain sufficient sensitivity. In addition, because the heating concentration step is carried out in an open environment, the risk of contamination of the sample water is also high. Therefore, as for the method of concentrating the metal components in the sample water, from the point of view of high concentration efficiency and low risk of contamination of the sample water in the concentration step, it is better to use a method such as the present embodiment to capture the metal components for concentration using a porous ion exchanger.

1: Ultrapure water production device 2: Primary pure water tank 3: Pump 4: Heat exchanger 5: Ultraviolet oxidation device 6: Ion exchange device 7: Ultrafiltration (UF) membrane device 8: Use point 10: Sampling device 11: Concentration column 20: Control device (evaluation equipment) _Ci , _Ci-1 : Metal concentration ΔC: Concentration difference between metal concentration Ci _{-1 and} metal concentration CiL1: Circulation pipeline L2: Sampling pipeline _ti , _ti-1 : Time Δt: Time difference between time ti _-1 and time _tiV1 : Valve

[Figure 1] is a schematic diagram showing the structure of an ultrapure water production device in an embodiment of the present invention. [Figure 2] is a graph showing an example of the change of metal concentration in sample water over time.

1: Ultrapure water production device

2: One-time pure water tank

3: Pump

4: Heat exchanger

5: Ultraviolet oxidation device

6: Ion exchange device

7: Ultrafiltration (UF) membrane device

8: Use point

10: Sampling device

11: Concentration column

20: Control device (evaluation equipment)

L1: Circulation pipeline

L2: Sampling pipeline

V1: Valve

Claims (9)

An operation management method for an ultrapure water production device is an operation management method for an ultrapure water production device having an ion exchange device, which comprises the following steps: Quantifying the metal components contained in the treated water from the ion exchange device over time; Obtaining the change of the concentration of the metal components over time based on the result of the quantitative measurement over time; and Evaluating the performance of the ion exchange resin filled in the ion exchange device based on the obtained change over time. The operation management method of the ultrapure water production device of claim 1, wherein the evaluation step includes: when the change in the concentration of the metal component per unit time is greater than a predetermined value, it is determined that the performance of the ion exchange resin is reduced. The operation management method of the ultrapure water production device as claimed in claim 2, wherein the predetermined value is set according to the error in quantifying the metal component. The operation management method of the ultrapure water production device of claim 2 or 3 further comprises the following step: when it is determined that the performance of the ion exchange resin has deteriorated, an alarm is issued to the user of the ultrapure water production device to urge the user to replace the ion exchange resin. The operation management method of the ultrapure water production device as claimed in claim 4 further comprises the following step: providing a new ion exchange resin to the user after the alarm is issued. An operation and management method for an ultrapure water production device as claimed in any one of claims 1 to 3, wherein the quantitative step comprises: repeatedly performing a series of treatments of passing a portion of the treated water through a container filled with a porous ion exchanger to capture the metal component in the treated water with the porous ion exchanger, allowing the captured metal component to elute into a lyse solution, and then quantitatively measuring the metal component in the lyse solution. The operation management method of the ultrapure water production device as claimed in claim 6, wherein the quantitative step includes: preparing a plurality of the containers, and repeating the series of treatments in parallel with staggered time for the plurality of containers. An operation management method for an ultrapure water production device as claimed in any one of claims 1 to 3, wherein the metal component includes sodium. An operation management system for an ultrapure water production device is an operation management system for an ultrapure water production device having an ion exchange device, and has: An evaluation device, which obtains the change of the concentration of the metal component over time from the quantitative value of the metal component contained in the treated water from the ion exchange device, and evaluates the performance of the ion exchange resin filled in the ion exchange device based on the obtained change over time.

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