Water quality measurement device, water treatment system, ion exchange resin cleaning system, and water quality measurement method

Abstract

The present invention appropriately manages the concentration of a nonvolatile dissolved substance contained in water to be measured flowing through a water treatment system or the like. This measurement device 5, which measures the water quality of water to be measured, comprises: an evaporation unit 52 that evaporates the water to be measured to form residual particles; and a determination unit 53 that determines the number of residual particles. This water treatment system 1 comprises a measurement device 5 that introduces water flowing through the water treatment system 1 as water to be measured and measures the water quality of the water to be measured. This ion exchange resin cleaning system 101 comprises: a container 102 in which an ion exchange resin 103 is cleaned; a cleaning water supply pipe L102 that supplies cleaning water to the container 102; a discharge pipe L104 that discharges cleaning wastewater; and a measurement device 5 that is connected to the discharge pipe L104 and measures the water quality of the cleaning wastewater.

Description

Water quality measurement device, water treatment system, ion exchange resin cleaning system, and water quality measurement method

[0001] This application is based on Japanese Patent Application Nos. 2024-192198 and 2024-192199 filed on October 31, 2024, and claims the priority based on these applications. These applications are incorporated herein by reference in their entirety. The present invention relates to a water quality measurement device, a water treatment system, an ion exchange resin cleaning system, and a water quality measurement method.

[0002] In a water treatment system, there is a method of determining the water quality of the water flowing through the water treatment system based on the number of fine particles contained in the water flowing through the water treatment system (see, for example, Japanese Patent Laid-Open No. 2019-136628). Also, in a water treatment system including an ion exchange device filled with an ion exchange medium, there is a method of determining the performance degradation of the ion exchange medium based on the number of fine particles contained in the treated water of the ion exchange device (see, for example, Japanese Patent Laid-Open No. 2019-136628).

[0003] The water flowing through the water treatment system may contain, in addition to particles, non-volatile dissolved substances that become particulate residues by drying. Also, the treated water of the ion exchange device may contain, in addition to particles, non-volatile dissolved substances that become particulate residues by drying. Such non-volatile dissolved substances may be harmful depending on the use of pure water. For example, in the cleaning and drying process of semiconductor wafers, there is a possibility that non-volatile dissolved substances are deposited as residues on the wafers when ultrapure water evaporates. Although the ion exchange resin filled in the ion exchange device may be washed in advance, if the ion exchange device is filled with washing wastewater containing non-volatile dissolved substances at a specific concentration or higher, non-volatile dissolved substances may flow out of the ion exchange device and the water quality of the treated water may deteriorate.

[0004] An object of the present invention is to provide a water treatment system capable of appropriately managing the concentration of non-volatile dissolved substances contained in the water flowing through the water treatment system. Another object of the present invention is to provide an ion exchange resin cleaning system capable of appropriately managing the cleaning of ion exchange resin. Another object of the present invention is to provide a water quality measurement device suitable for these systems.

[0005] The measuring device of the present invention measures the water quality of a target water. The measuring device comprises an evaporation unit that evaporates the target water to form residual particles, and a measuring unit that measures the number of residual particles. The water treatment system of the present invention has the above measuring device that introduces water flowing through the water treatment system as target water and measures the water quality of the target water. Furthermore, the ion exchange resin cleaning system of the present invention comprises a container for cleaning the ion exchange resin, a cleaning water supply pipe that supplies cleaning water to the container, a discharge pipe that discharges the cleaning wastewater, and the above measuring device connected to the discharge pipe that measures the water quality of the cleaning wastewater.

[0006] According to the present invention, it is possible to provide a water treatment system that can appropriately control the concentration of non-volatile dissolved substances contained in the water flowing through the water treatment system. Furthermore, according to the present invention, it is possible to provide an ion exchange resin cleaning system that can appropriately control the cleaning of the ion exchange resin. Furthermore, according to the present invention, it is possible to provide a water quality measuring device suitable for these systems.

[0007] The purposes, features, and advantages of this application, as described above and for other purposes, will become apparent from the detailed description below, with reference to the accompanying illustrations of this application.

[0008] This is a schematic diagram of the water treatment system according to the first embodiment. This is a schematic diagram of the measuring device. This is a schematic diagram of the water treatment system according to the second embodiment. This is a schematic diagram of the water treatment system according to the third embodiment (when the ion exchange device is in operation). This is a schematic diagram of the water treatment system according to the third embodiment (when the ion exchange device is started up). This is a schematic diagram of the ion exchange resin washing system according to the fourth embodiment. This is a schematic diagram showing an example of a water treatment system. This is a graph showing the relationship between the TOC concentration of the cation resin eluate and the number of residual particles. This is a graph showing the relationship between the TOC concentration of the PSS standard solution and the number of residual particles. This is a graph showing the relationship between the TOC concentration of the anionic resin eluate and the number of residual particles.

[0009] Embodiments of the water quality measuring device, water treatment system, and ion exchange resin washing system of the present invention will be described with reference to the drawings. In the following description, pure water means water with an electrical resistivity of 0.1 MΩ·cm or higher, and ultrapure water is pure water with an electrical resistivity of 15 MΩ·cm or higher (the maximum value is 18.24 MΩ·cm for theoretically pure water). In the following description, when it is not necessary to distinguish between pure water and ultrapure water, the term "pure water" will be used simply. Also, since fine particles and particles are not distinguished in this specification, fine particles and particles are used interchangeably.

[0010] (First Embodiment) Figure 1 shows a schematic configuration of a water treatment system 1 according to the first embodiment. The water treatment system 1 includes a primary pure water system 2 that produces pure water from raw water, and a secondary pure water system (hereinafter referred to as a subsystem) 3 that further removes impurities from the pure water produced by the primary pure water system 2 to produce ultrapure water of the water quality required at the use point 4. The primary pure water system 2 includes a raw water tank, a heat exchanger, a turbidity removal membrane device, an activated carbon tower, a decarbonation membrane device, a reverse osmosis membrane device, an ultraviolet irradiation device, a degassing membrane device, etc. (not shown).

[0011] Subsystem 3 includes a pure water tank 31, a pure water supply pump 32, an ultraviolet oxidation device 33, a hydrogen peroxide removal device 34, a non-regenerative mixed-bed first ion exchange device 35 (cartridge polisher), a membrane degasser 36, a booster pump 37, a non-regenerative mixed-bed second ion exchange device 38 (cartridge polisher), and an ultrafiltration membrane device 39. These are arranged in this order along the main pipe L1 and in series along the flow direction D of the water to be treated. Ultrapure water not used at use point 4 is returned to the pure water tank 31 by a return line L2 connected to the main pipe L1. The pure water tank 31 stores the pure water produced by the primary pure water system 2.

[0012] The pure water stored in the pure water tank 31 is sent to the ultraviolet oxidation device 33 by the pure water supply pump 32. The ultraviolet oxidation device 33 irradiates the water to be treated with ultraviolet light to decompose organic matter contained in the water. The hydrogen peroxide removal device 34 is equipped with an ion exchanger on which a catalyst such as palladium (Pd) or platinum (Pt) is supported, and decomposes oxidizing substances (hydrogen peroxide) generated by ultraviolet irradiation in the ultraviolet oxidation device 33. This prevents the subsequent first ion exchange device 35 from being damaged by oxidizing substances. The first ion exchange device 35 is filled with a mixed bed of cation exchange resin and anion exchange resin and removes ionic components from the water to be treated. The membrane degasser 36 removes dissolved oxygen and carbon dioxide contained in the water to be treated. The booster pump 37 is provided to pressurize the water to be treated, for example, when the use point 4 is located at a high location. The second ion exchange device 38 is an example of a water treatment device and removes fine particles and particulate components contained in the water to be treated. The second ion exchange device 38 is a non-regenerative ion exchange device.

[0013] The ultrafiltration membrane device 39 is an example of a membrane filtration device. An example of an ultrafiltration membrane device 39 is one that uses a membrane with a molecular weight cutoff of about 4000 to 6000 (corresponding to a pore size of 2-4 nm), which makes it possible to remove fine particles with a particle size of 10 nm or larger with a high probability. The membrane may be a hollow fiber membrane, a flat membrane, or a pleated membrane. It is also possible to use a system in which the filtration membrane is packed into a pipe, or a tower-like structure with multiple cartridges attached. The ultrafiltration membrane is preferably one that does not release impurities from the membrane itself, and polysulfone is suitably used. For example, fine particles flowing out from the resin of the first ion exchange device 35 are removed by the ultrafiltration membrane device 39, so the water quality of the ultrapure water supplied to the use point 4 is further improved.

[0014] Although not shown in the diagram, another filtration membrane device may be provided downstream of the ultrafiltration membrane device 39, for example, having a retaining diameter of 5 nm or less, preferably 3 nm or less, and more preferably 1 nm or less. The retaining diameter is the particle size at which the particle removal efficiency (PRE) is 80% or more, preferably 90%, and the PRE is measured according to the SEMI (Semiconductor Equipment and Materials International) standard C89-0116 "TEST METHOD FOR PARTICLE ROMOVAL PERFORMANCE OF LIQUID DILTER RATED BELOW 30 nm WITH INDUCITIVELY COUPLED PLASMA-MASS SPECTROSCOPY (ICP-MS)".

[0015] The configuration of subsystem 3 described above is just one example, and the configuration of subsystem 3 can be changed as appropriate. For example, a heat exchanger can be installed upstream of the ultraviolet oxidation device 33 (between the pure water supply pump 32 and the ultraviolet oxidation device 33). At least one of the hydrogen peroxide removal device 34, the first ion exchange device 35, and the booster pump 37 can be omitted. The membrane degasser 36 and the second ion exchange device 38 may be swapped with each other.

[0016] For water quality management standards of pure water, it is common to use concentrations of particulate matter, total organic carbon (TOC), hydrogen peroxide, metals, anions, and boron. Particulate matter is what originally existed as a solid in pure water and is also called native particle. However, although no control standards have been established, it has recently been pointed out that particulate precursors may be a contributing factor to the formation of residues on semiconductor wafers (see, for example, the International Roadmap for Devices and Systems (IRDS®)). Particulate precursors are non-volatile dissolved substances, and it is believed that the main source of particulate precursors in pure water is high-molecular-weight organic substances leached from resins and the like. In addition, high-molecular-weight substances that are not detected as particles due to refractive index, such as live bacteria and microorganisms, substances that normally dissolve in water but easily precipitate and form precipitates, such as silicic acid, and substances that are completely dissolved in water, such as NaCl and KCl, are also included in particulate precursors. Although particulate precursors dissolve in pure water, they precipitate as the surrounding water evaporates, becoming particulate residues. In the semiconductor wafer cleaning and drying process, semiconductor wafers are cleaned with ultrapure water and then dried, so particulate precursors contained in the ultrapure water used for cleaning may become particulate residues due to the evaporation of water and remain on the wafer surface. Since particulate precursors may not be removable even with the ultrafiltration membrane apparatus 39, it is becoming increasingly important to appropriately control and suppress the concentration of particulate precursors.

[0017] To address this issue, subsystem 3 includes a sampling line L3 that branches off from the main pipe L1 between the ultrafiltration membrane device 39 and the use point 4, and a measuring device 5 connected to the sampling line L3, which introduces the treated water from the ultrafiltration membrane device 39 and measures the water quality of the treated water. The sampling line L3 separates the treated water flowing between the ultrafiltration membrane device 39 and the use point 4. The measuring device 5 introduces the water flowing through the water treatment system 1 (subsystem 3 in this embodiment) (in this embodiment, the treated water from the ultrafiltration membrane device 39 flowing between the ultrafiltration membrane device 39 and the use point 4) as the water to be measured, and measures the water quality of the water to be measured. In this embodiment, a configuration in which the treated water flowing between the ultrafiltration membrane device 39 and the use point 4 is separated by the sampling line L3 and introduced into the measuring device 5 is illustrated, but for example, the treated water flowing between the ultrafiltration membrane device 39 and the use point 4 may be sampled in a container or the like and introduced into the measuring device 5. If another filtration membrane device is installed downstream of the ultrafiltration membrane device 39, a sampling line L3 can be provided between the other filtration membrane device and the use point 4. The measuring device 5 is a water quality measuring device using the spray drying method, and pure water flows continuously into the sampling line L3, and the measuring device 5 continuously measures the water quality of the incoming pure water. The sampling line L3 can be formed from metal or resin piping, resin tubes, etc. The measuring device 5 has a spray unit 51, an evaporation unit 52, a measurement unit 53, and a determination unit 54. In this embodiment, the spray unit 51, the evaporation unit 52, and the measurement unit 53 are a single unit, and the determination unit 54 is a device independent of the spray unit 51, the evaporation unit 52, and the measurement unit 53. An example of a unit consisting of the spray unit 51, the evaporation unit 52, and the measurement unit 53 is the STPC-3 from KANOMAX. The configuration of the measuring device 5 is not limited to this, and for example, the spray unit 51, the evaporation unit 52, the measurement unit 53, and the determination unit 54 may be a single unit. Since the determination unit 54 includes an arithmetic circuit, it can be configured as a personal computer, or as part of the control device (not shown) of subsystem 3.

[0018] Figure 2 shows the schematic configuration and measurement principle of the measuring device 5. The spray unit 51 has an introduction line 55 for the pure water to be measured, an introduction line 56 for nitrogen gas, and a spray nozzle 57. The spray nozzle 57 sprays the pure water to be measured using the driving force of the nitrogen gas, and condenses the pure water into droplets. Purified air from which impurities such as organic matter and water have been removed can also be used instead of nitrogen gas.

[0019] The evaporation unit 52 evaporates the treated water to form residual particles. That is, the evaporation unit 52 heats the droplets W generated by spraying and evaporates the water. The unique particles P1 exist in the pure water in the size and shape, or close to it, that were present when the pure water was removed. The unique particles that were present in the pure water are dried by the evaporation unit 52 as the surrounding water evaporates, forming an aerosol. The fine particle precursors are dissolved in the pure water, but as the surrounding water evaporates, they precipitate as particulate residue P2, also forming an aerosol. Therefore, the residual particles P include both the unique particles P1 formed by the removal of water by the evaporation unit 52 and the particulate residue P2 formed (precipitated) by the removal of water by the evaporation unit 52.

[0020] The measurement unit 53 continuously measures the number (concentration) of residual particles P contained per unit volume of water to be measured. The measurement unit 53 includes an alcohol supply unit 58 and an agglutination particle counter 59. The alcohol supply unit 58 supplies, for example, n-butyl alcohol to form supersaturated alcohol vapor around the residual particles P. The supersaturated alcohol vapor is cooled and condensed, causing alcohol droplets to condense and grow with the residual particles P as nuclei. The agglutination particle counter 59 counts the number of alcohol droplets A using the light scattering method. This makes it possible to detect residual particles P that are too small to be directly detected by the light scattering method. The agglutination particle counter 59 allows setting the minimum detectable particle size of alcohol droplets A, measures the number (concentration) of alcohol droplets A corresponding to the set minimum detectable particle size, and transmits the result to the determination unit 54. The measurement unit 53 may also include a display device that displays the number (concentration) of alcohol droplets A. Since alcohol without residual particles does not grow sufficiently as droplets, the agglutination particle counter 59 mainly counts the number of alcohol droplets A containing residual particles. By multiplying the obtained measurement value by a pre-calibrated coefficient, the number (concentration) of residual particles in pure water can be obtained.

[0021] Thus, because the measuring device 5 includes the processes of evaporation and drying, it can measure the concentration of both the intrinsic particles P1 that originally existed in the liquid as a solid and the particulate residue P2 derived from non-volatile dissolved matter. Since the residual particles P form alcohol droplets, this method can, in principle, measure residual particles down to a particle size of about 2.5 nm, which is the detection limit of the aggregated particle counter 59, and has the advantage that the measurement results are not affected by the refractive index or shape of the intrinsic particles or residual particles.

[0022] For example, in the case of STPC-3, the agglomerated particle counter 59 can be set to detect a minimum particle size of residual particles P of 3 nm or more, 9 nm or more, or 15 nm or more. That is, the agglomerated particle counter 59 can measure the number of residual particles with a particle size of 3 nm or more, the number of residual particles with a particle size of 9 nm or more, and the number of residual particles with a particle size of 15 nm or more. The agglomerated particle counter 59 cannot distinguish between intrinsic particles and particulate residue, but most of the residual particles with a particle size of 3 nm or more are thought to be particulate residue derived from the microparticle precursor, and most of the residual particles with a particle size of 15 nm or more are thought to be intrinsic particles. Therefore, in order to control the concentration of the microparticle precursor, it is preferable to measure the concentration of residual particles with a particle size of 3 nm or more.

[0023] The determination unit 54 determines whether the number of residual particles P measured by the measurement unit 53 exceeds a reference value. The determination unit 54 has a reference value stored in advance and compares the measured number with the reference value. When the determination unit 54 determines that the number of residual particles P exceeds the reference value, it generates at least one of the following: a signal indicating that the number of residual particles P exceeds the reference value, or a signal prompting the exchange of the ion exchanger.

[0024] Next, the operation method of subsystem 3 and the method for measuring the water quality of the water flowing through the water treatment system 1 (subsystem 3) will be described. As described above, during operation, the pure water stored in the pure water tank 31 becomes ultrapure water by passing through the pure water supply pump 32, ultraviolet oxidation device 33, hydrogen peroxide removal device 34, first ion exchange device 35, membrane degasser 36, booster pump 37, second ion exchange device 38, and ultrafiltration membrane device 39, and is supplied to the use point 4. If the quality of the ion exchange material is poor or the ion exchange material deteriorates, polymeric organic matter (particulate precursor) that constitutes the matrix will leach from the ion exchange material, typically an ion exchange resin, packed in the second ion exchange device 38. The water flowing through the water treatment system 1 (treated water from the second ion exchange device 38) is introduced into the measuring device 5 as the water to be measured. The measuring device 5 evaporates the water to be measured to form residual particles P, and continuously measures the number (concentration) of residual particles P contained per unit volume of the water to be measured.

[0025] When the number of measured residual particles P exceeds a standard value, the determination unit 54 generates at least one of the following: a signal indicating that the number has exceeded the standard value, or a signal prompting the replacement of the ion exchanger. The measuring device 5 can notify the outside as an alarm by any method, such as a message or voice, using these signals. Based on the alarm, the operator can determine that the ion exchanger may have deteriorated and take appropriate measures such as isolating the second ion exchanger 38, replacing the second ion exchanger 38, or replacing the ion exchanger.

[0026] (Second Embodiment) Figure 3 shows a schematic configuration of the water treatment system 1 according to the second embodiment. This embodiment is the same as the first embodiment, except that the sampling line L3 branches off from the main pipe L1 between the second ion exchange device 38 and the ultrafiltration membrane device 39. In the first embodiment, the water quality of the treated water from the ultrafiltration membrane device 39 was measured by the measuring device 5, but in this embodiment, the water quality of the treated water from the second ion exchange device 38 is measured by the measuring device 5. The sampling line L3 separates the treated water flowing between the second ion exchange device 38 and the ultrafiltration membrane device 39 as the water to be measured.

[0027] In a water treatment system similar to the first and second embodiments, the number of residual particles with a particle size of 3 nm or larger was measured using STPC-3, and in the first embodiment, it was 7.8 × 10 5 pieces / mL, 7.9 × 10 in the second embodiment. 5 The concentration was 100 particles / mL. This means that almost no particulate precursors were eluting from the ultrafiltration membrane device 39. In order to measure and manage the concentration of particulate precursors contained in the ultrapure water supplied to the use point 4, there is little difference whether the measuring device 5 measures the water quality of the treated water from the ultrafiltration membrane device 39 or the treated water from the second ion exchange device 38. In other words, even in the first embodiment, the measuring device 5 can be considered to introduce the treated water from the second ion exchange device 38 as the target water for measurement and measure the water quality of said target water. However, the first embodiment may be more advantageous than the second embodiment in that it directly confirms the water quality of the ultrapure water supplied to the use point 4.

[0028] If subsystem 3 is not equipped with a second ion exchange device 38, a sampling line L3 may be provided between the first ion exchange device 35 and the membrane degasser 36. That is, the measuring device 5 may introduce the treated water from the first ion exchange device 35 as the target water and perform water quality measurement on the target water, with the first ion exchange device 35 being an example of a water treatment device. Alternatively, sampling lines L3 may be provided between the first ion exchange device 35 and the membrane degasser 36, and between the second ion exchange device 38 and the ultrafiltration membrane device 39. In this case, multiple measuring devices 5 may be provided to simultaneously measure the water quality of the treated water (target water) from the first ion exchange device 35 and the second ion exchange device 38. Alternatively, the water quality of the treated water (target water) from the first ion exchange device 35 and the second ion exchange device 38 may be measured with a single measuring device 5 while switching between the two sampling lines L3.

[0029] (Third Embodiment) Figures 4A and 4B show a schematic configuration of the water treatment system 1 according to the third embodiment. Figure 4A shows the state of the second ion exchange devices 38A and 38B during normal operation, and Figure 4B shows the state of the second ion exchange device 38A during startup. In this embodiment, two second ion exchange devices 38A and 38B are provided in parallel. The main pipe L1 branches into two lines L1A and L1B, with the second ion exchange device 38A provided in line L1A and the second ion exchange device 38B provided in line L1B. Valves V1A and V1B are provided in lines L1A and L1B, respectively. Blow lines L4A and L4B branch from lines L1A and L1B, respectively, and valves V2A and V2B are provided in blow lines L4A and L4B, respectively. Blow lines L4A and L4B merge to form a single blow line L5, and a sampling line L3 branches from blow line L5. A measuring device 5 configured in the same manner as in the first embodiment is provided on the sampling line L3. The number of second ion exchange devices is not limited, and three or more second ion exchange devices can be provided in parallel.

[0030] During normal operation of the second ion exchange units 38A and 38B, valves V1A and V1B are open and valves V2A and V2B are closed, as shown in Figure 4A. The ion exchange performance of the two second ion exchange units 38A and 38B is measured by resistivity meters (not shown) installed in lines L1A and L1B, respectively. For example, if it is determined that the second ion exchange unit 38A has reached the end of its lifespan or if an abnormal resistivity value is detected, the operation of the second ion exchange unit 38A is stopped, valve V1A is closed to stop the flow of water to the second ion exchange unit 38A, and the second ion exchange unit 38A is replaced.

[0031] Since the water quality of the second ion exchange device 38A is unstable immediately after replacement, it is desirable to run water through it for a certain period of time (conditioning). Therefore, as shown in Figure 4B, valve V2A is opened and the entire amount of water that has been passed through the second ion exchange device 38A is blown out through blow lines L4A and L5. At this time, a portion of the water flowing through blow line L5 is supplied to sampling line L3, and the measuring device 5 introduces the treated water from the second ion exchange device 38A as the target water for measurement and measures the water quality of the target water.

[0032] The measurement unit 53 measures the number of residual particles in the same manner as in the first embodiment. When the number of residual particles falls below a standard value, the determination unit 54 generates at least one of the following signals: a signal indicating that the number of residual particles has fallen below a standard value, or a signal indicating that the startup of the second ion exchange device 38A is complete. The measuring device 5 can communicate these signals to the outside by any method, such as message or voice. Based on the notification, the operator can determine that the startup of the second ion exchange device 38A is complete and can restart the operation of the second ion exchange device 38A by closing valve V2A and opening valve V1A.

[0033] (Fourth Embodiment) As a fourth embodiment, an embodiment of the washing system for ion exchange resin will be described. The ion exchange resin is shipped after undergoing a purification process and a washing process of the raw material resin. Since the anion exchange resin and the cation exchange resin are supplied separately, they are purified and washed separately, and then mixed as needed before shipment. The anion exchange resin and the cation exchange resin may be purified, washed, and mixed in the same column. The purification process is a process of changing the ionic form of the ion exchange group of the ion exchange resin, changing the ionic form to the H form in the case of cation exchange resin and the ionic form to the OH form in the case of anion exchange resin. As the chemical solution for this, in the case of cation exchange resin, for example, an acidic solution such as HCl or HNO3 is used, and in the case of anion exchange resin, for example, an alkaline solution such as NaOH or TMAH (tetramethylammonium hydroxide) is used. The washing process is a process of washing away the chemical solution used in purification with ultrapure water.

[0034] Figure 5 shows a schematic configuration of the ion exchange resin washing system 101. The purification, washing, and mixing of the ion exchange resin may be performed in the same container or in separate containers, but in this embodiment, the purification, washing, and mixing are performed in the same container 102. Figure 5 shows the state during washing, and therefore, the container 102 shown in Figure 5 is filled with purified ion exchange resin. Since there is no significant difference in the purification and washing processes between anion exchange resin and cation exchange resin, in the following description, anion exchange resin and cation exchange resin will not be distinguished and will be referred to as ion exchange resin 103. Ion exchange resin 103 may be a mixture of anion exchange resin and cation exchange resin.

[0035] The cleaning system 101 includes a container 102 for cleaning the ion exchange resin 103, a chemical solution supply pipe L101 for supplying a purification chemical solution to the container 102, a cleaning water supply pipe L102 for supplying cleaning water (ultrapure water) to the container 102, and a discharge pipe L104 for discharging the used chemical solution and cleaning wastewater. The chemical solution supply pipe L101 and the cleaning water supply pipe L102 merge and connect to the container 102. For this reason, switching valves V101 and V102 are provided in the chemical solution supply pipe L101 and the cleaning water supply pipe L102. The chemical solution supply pipe L101 and the cleaning water supply pipe L102 may also be configured to connect to the container 102 separately without a merging section. The discharge pipe L104 may also be provided separately for discharging the used chemical solution and the cleaning wastewater.

[0036] As described above, particulate precursors may not be removable even by the ultrafiltration membrane device of an ultrapure water production system. Therefore, it is becoming increasingly important to appropriately manage and suppress the concentration of particulate precursors in the washing process of the ion exchange resin. To address this issue, the washing system 101 includes a sampling line L103 branching from the discharge pipe L104, and a measuring device 5 connected to the sampling line L103 for measuring the water quality of the washing wastewater. The sampling line L103 is equipped with a valve V103. The measuring device 5 is a water quality measuring device using the spray drying method. Washing wastewater flows continuously into the sampling line L103, and the measuring device 5 continuously measures the water quality of the washing wastewater. The sampling line L103 can be formed from metal or resin piping, resin tubes, etc. The measuring device 5 has the same configuration as the measuring device 5 of the first embodiment.

[0037] The evaporation unit 52 evaporates the washing wastewater to form residual particles. That is, the evaporation unit 52 heats the droplets W generated by spraying and evaporates the water. The specific particles P1 are present in the washing wastewater in the same size and shape as, or close to, that they were in when the washing wastewater was removed. The specific particles that were present in the washing wastewater are dried by the evaporation unit 52 as the surrounding water evaporates, forming an aerosol. The fine particle precursors are dissolved in the washing wastewater, but as the surrounding water evaporates, they precipitate as particulate residue P2, also forming an aerosol. Therefore, the residual particles P include both the specific particles P1 formed by the removal of water by the evaporation unit 52 and the particulate residue P2 formed (precipitated) by the removal of water by the evaporation unit 52.

[0038] The measurement unit 53 continuously measures the number (concentration) of residual particles P contained per unit volume of washing wastewater. The measurement unit 53 includes an alcohol supply unit 58 and an agglutination particle counter 59. The alcohol supply unit 58 supplies, for example, n-butyl alcohol to form supersaturated alcohol vapor around the residual particles P. The supersaturated alcohol vapor is cooled and condensed, causing alcohol droplets to condense and grow with the residual particles P as nuclei. The agglutination particle counter 59 counts the number of alcohol droplets A using the light scattering method. This makes it possible to detect residual particles P that are too small to be directly detected by the light scattering method. The agglutination particle counter 59 allows setting the minimum detectable particle size of alcohol droplets A, measures the number (concentration) of alcohol droplets A corresponding to the set minimum detectable particle size, and transmits the result to the determination unit 54. The measurement unit 53 may also include a display device that displays the number (concentration) of alcohol droplets A. Since alcohol without residual particles does not grow sufficiently as droplets, the agglutination particle counter 59 mainly counts the number of alcohol droplets A containing residual particles. By multiplying the obtained measurement value by a pre-calibrated coefficient, the number (concentration) of residual particles in the washing wastewater can be obtained.

[0039] The determination unit 54 determines whether the number of residual particles P measured by the measurement unit 53 is below a reference value. The determination unit 54 has a reference value stored in advance and compares the measured number with the reference value. When the determination unit 54 determines that the number of residual particles P is below the reference value, it generates at least one of the following signals: a signal indicating that the number of residual particles P is below the reference value, or a signal indicating that washing is complete.

[0040] Next, the operation method of the cleaning system 101 and the method for measuring the water quality of the cleaning wastewater will be explained. The container 102 is pre-filled with ion exchange resin 103. With valve V101 open and valves V102 and V103 closed, the chemical solution is injected into the container 102 from the chemical solution supply pipe L101 to purify the ion exchange resin 103. The used chemical solution is discharged from the discharge pipe L104. Next, as shown in Figure 5, with valve V101 closed and valves V102 and V103 open, cleaning water is injected into the container 102 from the cleaning water supply pipe L102 to clean the ion exchange resin 103. The cleaning wastewater is discharged from the discharge pipe L104. Polymeric organic matter (particulate precursor) that constitutes the matrix is ​​eluted from the ion exchange resin 103. A portion of the cleaning wastewater is introduced into the measuring device 5 from the sampling line L103. In this embodiment, a configuration is shown in which a portion of the washing wastewater is introduced into the measuring device 5 via the sampling line L103. However, for example, a portion of the washing wastewater may be sampled in a container or the like and introduced into the measuring device 5. The measuring device 5 evaporates the washing wastewater introduced into the measuring device 5 to form residual particles P, and continuously measures the number (concentration) of residual particles P contained per unit volume of washing wastewater.

[0041] When the number of measured residual particles P falls below a standard value, the determination unit 54 generates at least one of the following signals: one indicating that the number has fallen below the standard value, and another indicating that the cleaning is complete. The measuring device 5 can transmit these signals to the outside by any method, such as message or voice. Based on the notification, the operator can determine that the cleaning is complete and proceed to the next process, such as mixing and shipping the ion exchange resin 103.

[0042] In this embodiment, the process of purifying and washing new ion exchange resin has been described, but the process of purifying and washing used anion exchange resin and cation exchange resin can be carried out in the same manner. In this case, purification is synonymous with regeneration. If used anion exchange resin and cation exchange resin are supplied separately, purification and washing are performed in the same way as with new ion exchange resin. If used anion exchange resin and cation exchange resin are supplied in a mixed state, they are separated into anion exchange resin and cation exchange resin using the difference in specific gravity. After that, the anion exchange resin and cation exchange resin can be purified and washed together in the same container, or they can be purified and washed in separate containers. If the same container is used, the chemical solutions for the anion exchange resin and cation exchange resin are injected from different parts of the container and recovered from near the boundary between the anion exchange resin and cation exchange resin. If separate containers are used, the anion exchange resin and cation exchange resin are separated into separate containers, purified and washed, and then the anion exchange resin and cation exchange resin are mixed. Purification and washing can be carried out in the same way as with new ion exchange resin.

[0043] This embodiment is applicable to a purified or regenerated ion exchange resin before being filled into an ion exchange device provided in a water treatment system. FIG. 6 shows a schematic configuration diagram of an example of a water treatment system. The water treatment system 111 includes a primary pure water system 121 that produces pure water from raw water, and a secondary pure water system (hereinafter referred to as a subsystem) 131 that further removes impurities from the pure water produced by the primary pure water system 121 and produces ultrapure water with the water quality required at the use point 4. The primary pure water system 121 includes a raw water tank, a heat exchanger, a turbidity removal membrane device, an activated carbon tower, a decarbonation membrane device, a reverse osmosis membrane device, an ultraviolet irradiation device, a deaeration membrane device, etc. (not shown). The subsystem 131 includes a pure water tank 132, an ion exchange device 133, and an ultrafiltration membrane device 134, which are arranged in series along the main pipe L105 and in this order along the flow direction D of the treated water. Between the pure water tank 132 and the ion exchange device 133, a pure water supply pump, an ultraviolet oxidation device, a hydrogen peroxide removal device, an ion exchange device, a membrane deaeration device (not shown), etc. can be provided. The ultrapure water not used at the use point 4 is returned to the pure water tank 132 through a return line L106 connected to the main pipe L105. The pure water produced by the primary pure water system 121 is stored in the pure water tank 132. The ion exchange device 133 is filled with a mixed bed of cation exchange resin and anion exchange resin, and removes ionic components in the treated water. The ultrafiltration membrane device 134 removes fine particles, etc. The ion exchange device 133 is an example of the ion exchange device described above.

[0044] (Example) 50 mL of new cation exchange resin (product name: AMBERJET® ESG1024(H), manufactured by Organo Corporation) was mixed with 100 mL of pure water and shaken at 40°C for 16 hours to prepare an aqueous solution containing substances eluted from the cation exchange resin (hereinafter referred to as cation resin eluate). Similarly, 50 mL of new anion exchange resin (product name: AMBERJET® ESG4002(OH), manufactured by Organo Corporation) was mixed with 100 mL of pure water and shaken at 40°C for 16 hours to prepare an aqueous solution containing substances eluted from the anion exchange resin (hereinafter referred to as anion resin eluate). Next, the TOC concentrations of the cation resin eluate and the anion resin eluate were measured using a TOC meter (Sievers M9e). The TOC concentration of the cation resin eluate was 78,200 μg / L, and the TOC concentration of the anion resin eluate was 25,867 μg / L.

[0045] Next, dilutions were prepared by diluting the cation resin eluate 100-fold, 200-fold, and 300-fold with ultrapure water, and these were analyzed using KANOMAX's STPC-3. To determine the blank values, the ultrapure water used for dilution was also analyzed as a sample using the STPC-3. In addition to the samples, pure water, nitrogen gas (0.35 MPa), and 1-butanol (special grade, manufactured by Kanto Chemical Co., Ltd.) were supplied to the STPC-3. The analysis was performed using the batch mode of the STPC-3.

[0046] Figure 7 shows the relationship between the TOC concentration and the number of residual particles measured by STPC-3. Multiple measured values of the number of residual particles were obtained for each TOC concentration, and the average value of the measured values of the number of residual particles is shown in the graph (the same applies to Figures 8 and 9). The minimum detectable particle size of STPC-3 was set at 3 nm. As described above, the cation resin eluate supplied to STPC-3 is diluted at a dilution ratio of 100 to 300 times (referred to as A), but the sample supplied to STPC-3 is further diluted inside STPC-3 at a dilution ratio (referred to as B) equal to the flow rate ratio of pure water to the sample. Therefore, the TOC concentration on the horizontal axis of Figure 7 is not the value actually measured by the TOC meter, but the value obtained by dividing the TOC concentration of the cation resin eluate measured by the TOC meter by the dilution ratio A×B. The flow rate of pure water is 100 mL / min, and the flow rate of the sample was determined from the addition time and weight change of the sample. Since the flow rate of the sample was approximately 0.2 mL / min, the dilution ratio B inside STPC-3 was approximately around 500.

[0047] An exponential correlation was observed between the TOC concentration of the sample and the number of residual particles in Figure 7. Generally, it is considered that polystyrene sulfonic acid (PSS) elutes from the cation exchange resin, and from this example, it was confirmed that there is a possibility that PSS eluted from the cation exchange resin was detected by STPC-3. PSS is a high molecular weight organic substance that is a source of fine particle precursors. Therefore, in order to evaluate how much PSS elutes from the cation exchange resin, the cation resin eluate was analyzed by gel permeation chromatography (GPC). PSS with a molecular weight of 2400 to 575 was detected at 126 mg / L, PSS with a molecular weight of 575 to 310 was detected at 39 mg / L, and PSS with a molecular weight of 310 to 180 was detected at 20 mg / L. Substances with a molecular weight of 180 or less were also slightly detected, but it is highly likely that they are ions. From the above, it was found that only PSS with a molecular weight of less than 2400 substantially elutes from the new cation exchange resin, and it is highly likely that PSS eluted from the cation exchange resin was detected by STPC-3.

[0048] Next, PSS standard samples with molecular weights of 246, 2010, and 9680 (polystyrene sulfonate sodium salt, manufactured by SAS Co., Ltd.) were diluted to a PSS concentration of 1000 μg / L, and the TOC concentration was measured. Samples were also prepared by diluting the PSS standard samples to PSS concentrations of 10, 50, and 100 μg / L, and analyzed using STPC-3. As mentioned above, the samples were further diluted inside STPC-3. Figure 8 shows the relationship between TOC concentration and the number of residual particles measured by STPC-3. The TOC concentration on the horizontal axis is not the value actually measured by the TOC meter, but rather the value obtained by proportionally converting the measured TOC concentration of the 1000 μg / L diluted solution according to the PSS concentration of the sample. In all cases, a correlation was observed between TOC concentration and the number of residual particles in the range of TOC concentration from 0.005 μg / L to 0.053 μg / L. Although PSS with a molecular weight of 9680 does not leach from new cation exchange resin, it was found that detection is possible even if PSS with a large molecular weight leaches out for some reason. Generally, the detection accuracy of TOC meters is on the order of 0.1 μg / L (for this reason, the TOC concentration of the sample was calculated in this example as well), and it was difficult to control the concentration of PSS in the range of TOC concentration from 0.005 μg / L to 0.053 μg / L, but this example showed that it is possible.

[0049] Next, dilutions were prepared by diluting the anionic resin eluate 100, 200, and 300 times with pure water, and these were supplied to STPC-3 for analysis in the same manner as the cationic resin eluate. Figure 9 shows the relationship between TOC concentration and the number of residual particles measured by STPC-3. It is thought that mainly amines leach from the anionic resin eluate, and a similar trend was observed as with the cationic resin eluate, indicating that amine concentration can be detected using a similar method. Amines are high-molecular-weight organic substances that are the source of microparticle precursors.

[0050] While several preferred embodiments of the present invention have been described in detail, it should be understood that various changes and modifications are possible without departing from the spirit or scope of the appended claims.

[0051] 1 Water treatment system 4 Use point 5 Measuring device 38, 38A, 38B Second ion exchange device (water treatment device) 39 Ultrafiltration membrane device (filtration membrane device) 52 Evaporation unit 53 Measurement unit 54 Judgment unit 101 Ion exchange resin washing system 102 Container 103 Ion exchange resin L102 Washing water supply piping L104 Discharge piping

Claims

1. A measuring device for measuring the water quality of a target water, comprising: an evaporation unit that evaporates the target water to form residual particles; and a measuring unit that measures the number of residual particles.

2. A water treatment system having the measuring device described in claim 1, wherein the measuring device introduces water flowing through the water treatment system as the water to be measured.

3. The water treatment system according to claim 2, wherein the residual particles include particles dissolved in the water to be measured and precipitated when the water to be measured is evaporated in the evaporation section.

4. The water treatment system according to claim 2, wherein the measuring device has a determination unit that determines whether the number measured by the measuring unit exceeds a standard value, and when the determination unit determines that the number exceeds the standard value, it generates a signal indicating that the number has exceeded the standard value.

5. The water treatment system according to claim 4, comprising: an ion exchange device having an ion exchanger; a membrane filtration device provided downstream of the ion exchange device; and a sampling line for separating the water flowing between the membrane filtration device and a use point provided downstream of the membrane filtration device as the water to be measured, wherein the measuring device is connected to the sampling line.

6. The water treatment system according to claim 4, comprising: an ion exchange device having an ion exchanger; a membrane filtration device provided downstream of the ion exchange device; and a sampling line for separating the water flowing between the ion exchange device and the membrane filtration device as the water to be measured, wherein the measuring device is connected to the sampling line.

7. The water treatment system according to claim 5 or 6, wherein when the number exceeds the reference value during operation of the ion exchange device, the determination unit generates a signal prompting replacement of the ion exchange device.

8. The water treatment system according to claim 5 or 6, wherein when the number falls below the reference value during startup of the ion exchange device, the determination unit generates a signal indicating that the startup of the ion exchange device is complete.

9. The water treatment system according to claim 5 or 6, wherein the ion exchange device is a non-regenerative ion exchange device.

10. A water quality measurement method for measuring the water quality of water flowing through a water treatment system, comprising: introducing the water flowing through the water treatment system as the water to be measured into a measuring device according to claim 1; evaporating the water to be measured introduced into the measuring device to form residual particles; and measuring the number of residual particles with the measuring device.

11. A cleaning system for ion exchange resin, comprising: a container for cleaning ion exchange resin; a cleaning water supply pipe for supplying cleaning water to the container; a discharge pipe for discharging cleaning wastewater; and a measuring device according to claim 1, connected to the discharge pipe for measuring the water quality of the cleaning wastewater.

12. The cleaning system according to claim 11, wherein the residual particles include particles dissolved in the cleaning wastewater and precipitated as the cleaning wastewater is evaporated in the evaporation section.

13. The cleaning system according to claim 11, wherein the ion exchange resin filled in the container is an ion exchange resin that has been purified by passing a chemical solution through it.

14. The cleaning system according to claim 11, wherein the ion exchange resin filled into the container is the ion exchange resin before it is filled into an ion exchange device provided in the water treatment system.

15. The cleaning system according to claim 11, wherein the measuring device has a determination unit that determines whether the number measured by the measuring unit is below a reference value, and when the determination unit determines that the number is below the reference value, it generates a signal indicating that the number is below the reference value.

16. The cleaning system according to claim 15, wherein when the number falls below the reference value, the determination unit generates a signal indicating that cleaning is complete.

17. The cleaning system according to claim 11, wherein the measuring device continuously measures the number of residual particles.

18. A water quality measurement method for measuring the water quality of wastewater from washing an ion exchange resin, comprising: introducing the washing wastewater into a measuring device described in claim 1; evaporating the washing wastewater introduced into the measuring device to form residual particles; and measuring the number of residual particles with the measuring device.

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