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

Abstract

An operation management method for an ultrapure water production apparatus (1) having an ion exchange device (6) includes: a step for quantifying a metal component contained in treated water from the ion exchange device (6) over time; a step for acquiring a change over time in the concentration of the metal component on the basis of the result of the time quantification; and a step for evaluating the performance of the ion exchange resin filled in the ion exchange device (6) on the basis of the acquired change over time.

Description

Technical Field

[0001] The present invention relates to an operation management method and an operation management system for an ultrapure water production device. Background Art

[0002] In the manufacturing process of semiconductor devices and liquid crystal devices, ultrapure water with highly removed impurities is used in various applications such as cleaning processes. Even trace amounts of metal components contained in ultrapure water can have a significant impact on the characteristics of the device, so its concentration must be strictly controlled. 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.

[0003] Ultrapure water is generally produced by treating raw water (river water, groundwater, industrial water, etc.) in a pre-treatment system, a primary pure water system, and a secondary pure water system (subsystem) in sequence. Among them, 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 resins and is usually located at the most downstream side of the subsystem, or at the downstream side of the ultrafiltration membrane device located at the most downstream side of the subsystem. It is known that in the process of manufacturing ultrapure water, metal components are eluted from the pipes, pumps, etc. used, but the ion exchange device can suppress the impact on the quality of ultrapure water even if metal components are eluted on its upstream side.

[0004] In an ultrapure water production device equipped with such an ion exchange device, since the performance reduction 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 performance. Patent document 1 describes a method for performing a composition analysis of an adsorbed substance adsorbed on an ion exchange resin and judging the replacement period of the ion exchange resin based on the analysis result.

[0005] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2016-118408 Summary of the invention

[0006] Technical problem to be solved by the invention In the method described in Patent Document 1, in order to analyze the composition of the adsorbed substance, it is necessary to collect a portion of the ion exchange resin actually loaded from the ion exchange device as a sample. For this purpose, the supply of the treated water has to be stopped, thereby stopping the operation of the ion exchange device. In addition, with the collection of the ion exchange resin, there is a concern about the contamination of the device and the deterioration of the water quality of the treated water caused by it.

[0007] Therefore, an object of the present invention is to provide an operation management method and an operation management system for an ultrapure water production apparatus, which can appropriately determine whether or not replacement of an ion exchange resin due to performance degradation is necessary while maintaining stable operation.

[0008] Technical solutions for solving technical problems In order to achieve the above-mentioned purpose, the operation and management method of the ultrapure water production device of the present invention is an operation and management method of the ultrapure water production device with an ion exchange device, comprising: a process of quantifying the metal components contained in the treated water from the ion exchange device over time; a process of obtaining the time-dependent change of the concentration of the metal components based on the result of the time-dependent quantification; and a process of evaluating the performance of the ion exchange resin filled in the interior of the ion exchange device based on the obtained time-dependent change.

[0009] 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 unit. The evaluation unit obtains the time-dependent change of the concentration of the metal component based on 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 interior of the ion exchange device based on the obtained time-dependent change.

[0010] According to such an operation management method and operation management system of an ultrapure water production device, the performance of the ion exchange resin can be accurately evaluated by monitoring the actual water quality changes of the treated water from the ion exchange device. As a result, ultrapure water with good water quality can be stably produced, and the appropriate replacement period of the ion exchange resin can be grasped.

[0011] Effects of the Invention As described above, according to the present invention, it is possible to appropriately determine whether or not the ion exchange resin needs to be replaced due to a decrease in performance while continuing a stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram showing the structure of an ultrapure water production apparatus according to one embodiment of the present invention.

[0013] Figure 2 This is a graph showing an example of the change over time of the metal concentration in the sample water. DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this specification, an ultrapure water production device is exemplified, but the device to which the operation management method of the present invention can be applied is not limited thereto, and a pure water device may also be used.

[0015] Figure 11 is a schematic diagram showing the structure of an ultrapure water production apparatus according to an embodiment of the present invention. It should be noted that the structure of the ultrapure water production apparatus shown in the figure is only an example and does not limit the present invention.

[0016] The ultrapure water production device 1 includes 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. These are connected by a circulation line L1 to form a secondary pure water system (subsystem), and the primary pure water produced by the primary pure water system (not shown) is sequentially processed to produce ultrapure water, and the ultrapure water is supplied to a use point 8.

[0017] 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 whose temperature is adjusted by the heat exchanger 4 is supplied to the ultraviolet oxidation device 5 and irradiated with ultraviolet rays. In this way, the total organic carbon (TOC) in the treated water is decomposed. Then, the treated water is treated by ion exchange treatment in the ion exchange device 6 to remove metals and the like, and particles are removed in the UF membrane device 7. A part of the ultrapure water obtained in this way is supplied to the use point 8, and the remaining part is returned to the primary pure water tank 2. Primary pure water is supplied to the primary pure water tank 2 from the primary pure water system (not shown) as needed. As 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, devices generally used in the subsystem of the ultrapure water production device can be used. For example, as the ion exchange device 6, a non-regenerative mixed bed ion exchange device (cartridge polisher) filled with cation exchange resin and anion exchange resin in a mixed bed can be used.

[0018] In the ultrapure water manufacturing device 1, when the ultrapure water manufactured is used for cleaning semiconductor devices, liquid crystal devices, etc., as mentioned above, it is required to strictly manage the metal concentration in the ultrapure water. The metal concentration at this time is greatly affected by the performance of the ion exchange resin filled in the ion exchange device 6. That is, if the performance of the ion exchange resin is reduced, the metal components contained in the treated water are not removed by the ion exchange device 6 and leak into the ultrapure water, and the water quality of the ultrapure water cannot meet the required level. Therefore, as an operation management for supplying ultrapure water with stable water quality to the use point 8, it is necessary to accurately evaluate the performance of the ion exchange resin and judge whether the ion exchange resin needs to be replaced based on this. In order to evaluate the performance of the ion exchange resin, in the present embodiment, the metal concentration in the treated water from the ion exchange device 6 is analyzed. Therefore, a sampling device 10 is provided in the ultrapure water manufacturing device 1, and the sampling device 10 collects the metal components contained in the treated water from the ion exchange device 6.

[0019] The sampling device 10 is composed of a sampling pipe L2 and a concentration column 11 arranged in the sampling pipe L2. The sampling pipe L2 is connected to the circulation line L1 between the ion exchange device 6 and the UF membrane device 7 via a valve V1. The concentration column 11 captures and concentrates the metal components in the sample water (treated water from the ion exchange device 6) supplied through the sampling pipe L2, and has a porous ion exchanger as a capturing member inside. As the porous ion exchanger, for example, an ion adsorption membrane (especially a porous membrane with cation exchange capacity) can also be used. From the point of view of being able to pass water at a higher spatial velocity and shortening the time required for concentration, it is preferred to use a monolithic organic porous ion exchanger. It should be noted that at least the liquid contact part of the sampling device 10 is preferably non-metallic, for example, preferably made of synthetic resin, and particularly preferably made of fluororesin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and polypropylene (PP).

[0020] 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 results will be described.

[0021] First, open valve V1, supply a portion of the treated water from the ion exchange device 6 as sample water to the sampling pipe L2 and pass the water to the concentration column (container) 11. In this way, the metal components in the sample water are captured and concentrated by the porous ion exchanger filled in the concentration column 11. The water passing time (concentration time) at this time also depends on the amount of water passed to the concentration column 11, but as long as it is concentrated to the extent that the metal components to be analyzed can be quantified with sufficient accuracy, it is not particularly limited, for example, several days. Then, after the given water passing time has passed, close valve V1 and stop passing water to the concentration column 11. Then, remove the concentration column 11 from the sampling pipe L2 and recover the porous ion exchanger filled inside.

[0022] Next, the metal components captured by the recovered porous ion exchanger are eluted into an eluent (e.g., nitric acid diluted to a given concentration). The metal components in the eluent are then quantified, and the metal concentration in the sample water is calculated based on the obtained metal amount (quantitative value). As a quantitative method for 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 as a value obtained by dividing the obtained metal amount by the concentration ratio of the eluent.

[0023] Here, the type of metal component to be analyzed is not particularly limited, for example, at least any one of Na, K, Ca, Mg, Fe, Cu, Al, Zn, Ni, Cr and Pb can be used as the object of analysis. Among them, Na (sodium) is preferably used as the object of analysis. This is because, compared with other metal components, Na (sodium) is present in a large amount in the treated water supplied to the ion exchange device 6 (although it also depends on the water quality of the raw water and the structure of the primary pure water system), and is difficult to be adsorbed by the cation exchange resin in the ion exchange device 6 (low selectivity). That is, if the performance of the ion exchange resin decreases, sodium will no longer be adsorbed before other metal components, resulting in an increase in the sodium concentration in the treated water. Therefore, by using sodium as the object of analysis, it is possible to predict in advance that other metal components will leak from the ion exchange device 6, and ultrapure water with good water quality can be stably supplied to the point of use 8. It should be noted that the metal component referred to here refers to a form containing both metal ions and metal particles (microparticles).

[0024] Such quantitative analysis is repeated over time (preferably periodically), and based on the results, the temporal variation of the metal concentration in the sample water is obtained. That is, after the concentrating column 11 is removed from the sampling pipe L2 in order to analyze the captured metal components, another concentrating column 11 is installed in the sampling pipe L2. The metal components in the sample water are captured and analyzed again using this concentrating column 11. Then, the calculated metal concentration is plotted against the water flow time to the ion exchange device 6 at the time when the concentrating column 11 is removed (the elapsed time from the start of the use of the ion exchange resin) to obtain the temporal variation of the metal concentration in the sample water. Then, based on the temporal variation obtained in this way, the performance of the ion exchange resin filled in the ion exchange device 6 is evaluated. Below, refer to Figure 2 A specific evaluation method will be described. Figure 2 This is a graph showing an example of the change over time of the metal concentration in the sample water.

[0025] If at time t i Get the metal concentration C i , then based on the time t at which the metal concentration was obtained before i-1 And the metal concentration C at this time i-1 , calculate the change in metal concentration per unit time ΔC / Δt. Here, Δt is the time t i-1 With time t i The time difference (=t i -t i-1 ), ΔC is the metal concentration C i-1 and metal concentration C i The concentration difference (=C i -C i-1). Then, it is determined whether the calculated change amount ΔC / Δt is greater than a preset given value. If it is greater than the given value, it is determined that the metal component to be analyzed is not removed by the ion exchange device 6 and leaks, and therefore, it is determined that the performance of the ion exchange resin in the ion exchange device 6 is reduced. It should be noted that the given value at this time is not particularly limited and can be pre-set based on experimental verification, but is preferably set based on the error in the above-mentioned quantitative analysis. That is, if the quantitative error becomes larger, the change in metal concentration caused by the reduced performance of the ion exchange resin is masked by the error and may not be accurately detected. Therefore, it is preferred that the larger the quantitative error, the larger the given value.

[0026] Thus, according to the present embodiment, by monitoring the actual water quality change (the concentration change of the metal component 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, ultrapure water with good water quality can be stably manufactured, and the appropriate replacement period of the ion exchange resin can be grasped. It should be noted that, in order to evaluate the performance of the ion exchange resin, for example, it is also possible to consider performing the above-mentioned quantitative analysis once, and comparing the quantitative value (metal concentration) obtained each time with a given threshold value. However, in such a method, it is confirmed that the quantitative value exceeds the threshold value, and thus, at the moment of confirming that the performance of the ion exchange resin is reduced, the ultrapure water whose water quality has deteriorated is supplied to the use point. Therefore, it is also preferred 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, from the point of view that it can be predicted before the performance of the ion exchange resin is reduced.

[0027] The above-mentioned performance evaluation of the ion exchange resin can be performed by the manager of the ultrapure water manufacturing device 1, but can also be performed by the operation management system that performs the operation management of the ultrapure water manufacturing device 1. That is, the control device (evaluation unit) 20 of the operation management system can also obtain the time-dependent change of the metal concentration in the sample water based on the input data (quantitative value of the metal component or the metal concentration in the sample water calculated therefrom) input by the manager of the ultrapure water manufacturing device 1, and evaluate the performance of the ion exchange resin by the above-mentioned method based on the obtained time-dependent change. In addition, at this time, it is preferred that the control device 20 issues an alarm to the manager of the ultrapure water manufacturing device 1 to urge the replacement of the ion exchange resin when it is determined that the performance of the ion exchange resin has decreased.

[0028] On the other hand, the performance evaluation of the ion exchange resin, including the quantitative analysis after the concentration column 11 is removed from the ultrapure water manufacturing device 1, is mostly performed at a location far away from the site where the ultrapure water manufacturing device 1 is installed. In such a case, when it is determined that the performance of the ion exchange resin is reduced at a location far away from the site, in order to be able to respond more quickly on site, it is preferred to issue an alarm to the on-site staff (users) to urge 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 is also possible to provide (sell) a new ion exchange resin to the user of the ultrapure water manufacturing device 1 after the alarm is issued.

[0029] In order to evaluate the performance of the ion exchange resin more accurately, it is preferred to implement the above-mentioned quantitative analysis at the shortest possible intervals to 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, so it takes time to pass the water. Therefore, the time interval for shortening the time series data is limited. Therefore, the sampling pipeline L2 can also be branched into multiple ones, or multiple sampling pipelines L2 can be set, and a concentration column 11 can be set in each of them. On this basis, the above-mentioned series of processes from capturing the metal components to quantification are repeatedly performed on each concentration column 11 at staggered times in parallel. As a result, compared with the case where a series of processes are repeatedly performed using a single concentration column 11, the time interval for obtaining the metal concentration can be shortened.

[0030] It should be noted that as a method for concentrating metal components in sample water, in addition to the above-mentioned method of using a porous ion exchanger, a method of heating and concentrating the collected sample water is also considered. However, in this method, the concentration ratio caused by heating is limited, and in order to obtain sufficient sensitivity, a large amount of sample water needs to be collected. In addition, the heating and concentration process is carried out in an open environment, so the risk of sample water contamination also increases. Therefore, as a method for concentrating metal components in sample water, from the point of view of high concentration efficiency and low risk of contamination of sample water in the concentration process, it is preferred to use a method of capturing and concentrating metal components with a porous ion exchanger as in the present embodiment.

[0031] Description of Reference Numerals 1 Ultrapure water production device 2 Primary pure water tank 3 Pumps 4 Heat exchanger 5. Ultraviolet oxidation device 6 Ion exchange device 7 Ultrafiltration membrane device 8 Use Points 10 Sampling device 11 Concentration column L1 circulation line L2 Sampling Pipe V1 valve.

Claims

1. An operation management method for an ultrapure water production device, wherein the ultrapure water production device has an ion exchange device, and the operation management method for the ultrapure water production device comprises: a quantitative step of quantitatively determining the metal components contained in the treated water from the ion exchange device over time; A step of obtaining a temporal change in the concentration of the metal component based on the result of the temporal quantitative determination; and A step of evaluating the performance of the ion exchange resin filled in the ion exchange device based on the acquired change over time.

2. The operation management method of the ultrapure water production device according to claim 1, wherein: The step of evaluating includes determining that the performance of the ion exchange resin is degraded when the amount of change per unit time in the concentration of the metal component is equal to or greater than a given value.

3. The operation management method of the ultrapure water production device according to claim 2, wherein: The given value is set based on an error in quantifying the metal component.

4. The operation management method of the ultrapure water production device according to claim 2 or 3, wherein: The operation management method of the ultrapure water production apparatus further includes the step of issuing an alarm to urge a user of the ultrapure water production apparatus to replace the ion exchange resin when it is determined that the performance of the ion exchange resin has deteriorated.

5. The operation management method of the ultrapure water production device according to claim 4, wherein: The operation management method of the ultrapure water production device further includes the step of providing a new ion exchange resin to the user after the alarm is issued.

6. The operation management method of an ultrapure water production device according to any one of claims 1 to 3, wherein: The quantification process includes repeatedly performing the following series of treatments: passing a portion of the treated water through a container filled with a porous ion exchanger so as to capture the metal component in the treated water by the porous ion exchanger, eluting the captured metal component into an eluent, and quantifying the metal component in the eluent.

7. The operation management method of the ultrapure water production device according to claim 6, wherein: The quantitative step includes preparing a plurality of the containers and repeatedly performing the series of processes in parallel with respect to the plurality of containers at different times.

8. The operation management method of an ultrapure water production device according to any one of claims 1 to 3, wherein: The metal component includes sodium.

9. An operation management system for an ultrapure water production device, the ultrapure water production device having an ion exchange device, wherein: The operation management system of the ultrapure water production device has an evaluation unit, which obtains the time-dependent change in the concentration of the metal component based on 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 interior of the ion exchange device based on the obtained time-dependent change.

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