A performance evaluation apparatus for a membrane filtration system in a pure water production apparatus, a pure water production system using the same, and a method for evaluating the performance of a membrane filtration system in a pure water production apparatus.

Abstract

To more specifically evaluate a performance deterioration in a membrane filtration device while suppressing influence to be given to the operation of a pure water manufacturing device.SOLUTION: A performance evaluation device 2 of a membrane filtration device is a performance evaluation device of a membrane filtration device of a pure water manufacturing device. The performance evaluation device 2 includes branch lines L11 to L15 that branch at an inlet part of a membrane filtration device 18 from a line L1 on which the membrane filtration device 18 of the pure water manufacturing device, and at least one filtration device for evaluation 21A to 21D connected to the branch lines L12 to L15. The at least one filtration device for evaluation 21A to 21D has the same kind of a membrane as the membrane filtration device 18, and the membrane area of the membrane of the at least one filtration device for evaluation 21A to 21D is smaller than the membrane area of the membrane filtration device 18.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a performance evaluation device for a membrane filtration device of a pure water production apparatus, a pure water production system using the same, and a method for evaluating the performance of a membrane filtration device of a pure water production apparatus.

Background Art

[0002] At the end of an ultrapure water production apparatus (subsystem), a membrane filtration device such as an ultrafiltration membrane device is installed for the purpose of removing fine particles. As the requirements for ultrapure water quality become stricter, the requirements for the membrane filtration device installed at the end of the subsystem are also becoming stricter. Conventionally, ultrapure water has been managed for fine particles having a particle size of 50 nm or more, but in recent years, management of fine particles having a particle size on the order of 10 nm has been demanded.

[0003] One of the factors that increases the number of fine particles at the end of the subsystem is deterioration or breakage of the membrane filtration device (specifically, the membrane module in the membrane filtration device). The membrane filtration device originally installed to remove fine particles may become a source of fine particles due to deterioration or breakage, and as a result, it may affect the number of fine particles in the outlet water of the membrane filtration device. Therefore, management of the membrane filtration device at the end of the subsystem is very important. Patent Document 1 discloses a method for diagnosing an ultrafiltration membrane that measures the number of coarse particles in the permeated water and concentrated water of the ultrafiltration membrane and determines that the ultrafiltration membrane has deteriorated when a predetermined threshold value is exceeded. Specifically, the permeated water of the ultrafiltration membrane is sampled, fine particles in the sampled water are captured by a membrane filtration device, and the captured fine particles are observed with a scanning electron microscope (SEM).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the diagnostic method described in Patent Document 1, it is possible to obtain a sample of fine particles while continuing to operate a pure water production system, including an ultrapure water production system. However, since the evaluation of the membrane filtration system depends solely on the sampled water, there are limitations to evaluating the condition of the membrane filtration system in detail.

[0006] The present invention aims to provide a performance evaluation device for a membrane filtration system in a pure water production system that can evaluate the performance degradation of the membrane filtration system in more detail while minimizing the impact on the operation of the pure water production system. [Means for solving the problem]

[0007] The performance evaluation apparatus for a membrane filtration apparatus of the present invention is a performance evaluation apparatus for a membrane filtration apparatus of a pure water production apparatus. The performance evaluation apparatus has a branch line that branches off from the line on which the membrane filtration apparatus of the pure water production apparatus is installed at the inlet of the membrane filtration apparatus, and at least one evaluation filtration membrane apparatus connected to the branch line. The at least one evaluation filtration membrane apparatus has a membrane of the same type as that of the membrane filtration apparatus, and the membrane area of ​​the membrane of the at least one evaluation filtration membrane apparatus is smaller than the membrane area of ​​the membrane of the membrane filtration apparatus. In one embodiment, at least one evaluation filtration membrane apparatus has at least one first module, and the performance evaluation apparatus further has a membrane property evaluation apparatus for evaluating the membrane properties of at least one first module, the membrane property evaluation apparatus measures at least one of the elongation retention rate of the threads constituting the membrane of at least one first module and the fractionation retention rate of at least one first module. In another embodiment, at least one evaluation filtration membrane apparatus has at least one second module, and the performance evaluation apparatus has an addition line connected to the inlet of at least one second module of the branching line for adding an evaluation substance, and a detection device provided at the outlet of at least one second module before the branching line for detecting the evaluation substance. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a performance evaluation device for a membrane filtration system in a pure water production system that can evaluate the performance degradation of the membrane filtration system in more detail while minimizing the impact on the operation of the pure water production system. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of an ultrapure water production apparatus according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a performance evaluation device for ultrafiltration membrane systems. [Figure 3] This is a schematic diagram of the test apparatus used in the example. [Modes for carrying out the invention]

[0010] Figure 1 shows an overview of a subsystem of an ultrapure water production apparatus 1 according to one embodiment of the present invention. Figure 2 is an enlarged view of part A in Figure 1 and shows an overview of the performance evaluation apparatus 2. The subsystem is a system for producing ultrapure water supplied to the point of use (POU) from pure water produced by a primary pure water system (not shown), and is also called a secondary pure water system. The following description of the ultrapure water production apparatus 1 refers to the subsystem unless otherwise specified, and the subsystem may be referred to as the ultrapure water production apparatus 1. The ultrapure water production apparatus 1 is used in the manufacturing process of electronic components such as semiconductors.

[0011] The subsystem of the ultrapure water production apparatus 1 includes a main line L1 connected to a point of use POU, multiple water treatment devices provided on the main line L1 for producing ultrapure water, and a return line L2 that returns ultrapure water that is not used (more precisely, was not used) at the point of use POU back to the main line L1. On the main line L1, a pure water tank 11, a pure water supply pump 12, a heat exchanger 13, an ultraviolet oxidation device 14, an ion exchange device 15, a membrane degasser 16, a booster pump 17, and an ultrafiltration membrane device 18 are arranged in series along the pure water flow direction D in the order described. The ultraviolet oxidation device 14, ion exchange device 15, membrane degasser 16, and ultrafiltration membrane device 18 are examples of the water treatment devices described above. Multiple supply lines L3 that supply ultrapure water to each point of use POU branch off from the main line L1. Multiple recovery lines L4 that recover ultrapure water that was not used at each point of use POU merge into the return line L2. The return line L2 is connected to the pure water tank 11. The ultrapure water that flows from the recovery line L4 into the return line L2 is returned to the main line L1 through the return line L2 and the pure water tank 11.

[0012] The pure water tank 11 stores pure water produced by the primary pure water system. The pure water supply pump 12 supplies the pure water stored in the pure water tank 11 to the heat exchanger 13. The ultraviolet oxidation device 14 irradiates the pure water, whose temperature has been adjusted in the heat exchanger 13, with ultraviolet light to decompose organic matter contained in the pure water. The ion exchange device 15 removes ionic components from the pure water. The ion exchange device 15 is a non-regenerative cartridge polisher with a mixed bed of cation exchange resin and anion exchange resin. The membrane degasser 16 degasses the pure water, i.e., removes dissolved oxygen and carbon dioxide contained in the pure water. The booster pump 17 is installed to pressurize the pure water, for example, when the point of use (POU) is located at a high location. The booster pump 17 may be omitted depending on the location of the point of use (POU). The ultrafiltration membrane device 18 finally removes fine particles contained in the pure water. The ultrafiltration membrane device 18 has a hollow fiber membrane module filled with hollow fiber membranes. Compared to flat membranes and pleated membranes, hollow fiber membranes allow for a higher packing density in the filtration membrane module, thus increasing the amount of permeate per module. Furthermore, hollow fiber membrane modules are easy to maintain a high level of cleanliness, enabling shipment, installation in ultrapure water production equipment, and on-site replacement while maintaining high cleanliness. Examples of hollow fiber membrane modules include those made of polysulfone with a molecular weight cutoff of approximately 4000 to 6000, such as Asahi Kasei's OLT-6036H and Nitto Denko's NTU-3306-K6R (both with a molecular weight cutoff of 6000). The molecular weight cutoff generally refers to the approximate molecular weight of the spherical solute (protein) that can be retained by the membrane at a concentration of 90% or more.

[0013] The ultrapure water production apparatus 1 has a performance evaluation apparatus 2 for evaluating the performance (degree of degradation) of the ultrafiltration membrane apparatus 18. The performance evaluation apparatus 2 has branch lines L11 to L15 that branch off from the main line L1 at the inlet of the ultrafiltration membrane apparatus 18, and at least one evaluation filtration membrane apparatus 21 connected to the branch lines L11 to L15. In this embodiment, it has two first modules (first evaluation filtration membrane apparatuses) 21A and 21B and two second modules (second evaluation filtration membrane apparatuses) 21C and 21D. The branch lines L11 to L15 have a first line L11 connected to the main line L1, and second to fifth lines L12 to L15 branching from the first line L11. Two first modules 21A and 21B are provided on the second and third lines L12 and L13, respectively, and two second modules 21C and 21D are provided on the fourth and fifth lines L14 and L15, respectively. It is preferable that the branch lines L11 to L15 (first line L11) be provided between the ultrafiltration membrane device 18 and the water treatment device closest to the ultrafiltration membrane device 18 upstream of the ultrafiltration membrane device 18, that is, between the membrane degasser 16 and the ultrafiltration membrane device 18 (inlet of the ultrafiltration membrane device 18). However, as long as the number of particulate matter does not change significantly, they may also be provided on the upstream side of the closest water treatment device. For example, as in the embodiment, the branching lines L11 to L15 may branch from between the ion exchange device 15 and the membrane degasser 16. Alternatively, the ion exchange device 15 may be provided between the membrane degasser 16 and the ultrafiltration membrane device 18, and the branching lines L11 to L15 may branch from between the ion exchange device 15 and the ultrafiltration membrane device 18.

[0014] The first modules 21A and 21B and the second modules 21C and 21D are equipped with the same type of membrane as the ultrafiltration membrane device 18. The same type of membrane refers to a membrane that has the same material, pore size, and dimensions (inner and outer diameters of the hollow fibers, and length of the hollow fibers) and has the same filtration performance, but also includes membranes that have similar materials, pore size, and dimensions and have equivalent filtration performance. In this embodiment, the first and second modules 21A to 21D and the ultrafiltration membrane device 18 are evaluation filtration membrane devices in which a large number of hollow fiber membranes are filled into a container, and the material, pore size, and dimensions of the hollow fiber membranes are common to the first and second modules 21A to 21D and the ultrafiltration membrane device 18. However, the number of hollow fiber membranes in each of the first and second modules 21A to 21D is less than the number of hollow fiber membranes in the ultrafiltration membrane device 18. As a result, the membrane area of ​​each hollow fiber membrane in the first and second modules 21A to 21D (the value obtained by multiplying the membrane area of ​​each hollow fiber membrane by the number of hollow fiber membranes) is smaller than the membrane area of ​​the hollow fiber membrane in the ultrafiltration membrane device 18. In other words, the first and second modules 21A to 21D are small-scale evaluation filtration membrane devices that mimic the ultrafiltration membrane device 18. The membrane areas of the hollow fiber membranes in the first and second modules 21A to 21D are the same, but they may be different from each other.

[0015] First and second water quality meters C1 and C2 are provided at the outlets of the first modules 21A and 21B of the second and third lines L12 and L13. The first and second water quality meters C1 and C2 are particulate meters. Instead of particulate matter, TOC (total organic carbon) may be measured, or the concentration of dissolved substances such as metals and organic matter may be measured. As will be described later, the first modules 21A and 21B are provided to estimate the deterioration of the ultrafiltration membrane device 18, so the measurement target is not limited to substances that can be captured by the ultrafiltration membrane device 18. The ultrafiltration membrane device 18 is basically for capturing particulate matter, but it also has the ability to capture dissolved substances such as organic matter and metals if they are in granular or colloidal form. Therefore, the first and second water quality meters C1 and C2 only need to measure at least one of the number of particulate matter, TOC, or metal concentration.

[0016] Examples of the first and second water quality meters C1 and C2 include a water quality meter using the spray drying method (e.g., KANOMAX's STPC3). This water quality meter has a spraying unit, an evaporation / drying unit, and a detection unit. The spraying unit samples and sprays the ultrapure water to be measured. The evaporation / drying unit removes the larger droplets generated by the spraying, and heats and evaporates the remaining fine droplets. Particles present in the ultrapure water and particles made from dissolved non-volatile residues form aerosols. The evaporation / drying unit further removes water by passing the aerosols through a quasi-permeable membrane. The detection unit classifies the precipitated aerosols by size using a differential electrostatic classifier and measures the number concentration of the classified particles with a condensed particle counter. By multiplying the obtained measurement value by a pre-calibrated coefficient, the particle concentration in the ultrapure water is obtained. In principle, this method can measure particles down to about 2.5 nm in diameter, which is the detection limit of the condensed particle counter, and has the advantage that the measurement results are not affected by the refractive index or shape of the particles.

[0017] Conventionally, water quality meters such as particle meters have been installed between the ultrafiltration membrane device 18 and the use point POU, but it is difficult to determine the deterioration of the ultrafiltration membrane device 18 based on these alone. Therefore, conventionally, a direct inspection method has been used to determine the deterioration of the ultrafiltration membrane device 18 by sampling the permeate water on the outlet side of the ultrafiltration membrane device 18 or the concentrated water in the inlet space inside the ultrafiltration membrane device 18 and observing it with an SEM. However, this method requires a long time for sampling and makes online measurement difficult. The first and second water quality meters C1 and C2 have higher particle detection accuracy than the particle meters installed between the ultrafiltration membrane device 18 and the use point POU, and moreover, they measure the number of particles in the outlet water of the first modules 21A and 21B online, so it is possible to quickly grasp the signs and degree of deterioration of the first modules 21A and 21B, and as a result, the signs and degree of deterioration of the ultrafiltration membrane device 18. Furthermore, by using it in conjunction with the water quality meter installed between the ultrafiltration membrane device 18 and the use point POU, more reliable evaluation becomes possible.

[0018] The performance evaluation device 2 includes a membrane property evaluation device 22 for evaluating the membrane properties of the first modules 21A and 21B. The membrane property evaluation device 22 measures and evaluates the properties of the membrane, for example, by measuring and evaluating the elongation retention rate and fractionation retention rate of the hollow fibers. It may also output these measured values ​​and evaluation results. In the present invention, at least one, preferably both, of the elongation retention rate and fractionation retention rate of the hollow fibers constituting the membranes of the first modules 21A and 21B is measured. The membrane property evaluation device 22 is equipment independent of the first modules 21A and 21B. The elongation retention rate is determined as follows: A single hollow fiber membrane is taken from the first modules 21A and 21B, mounted in the membrane property evaluation device 22, and tensile stress is applied until it breaks, and the tensile stress A at the time of breakage is determined. Similarly, a new (unused) hollow fiber membrane identical to the one filled in the first modules 21A and 21B is mounted on the membrane property evaluation device 22, and tensile stress is applied until it breaks, and the tensile stress B at the time of breakage is determined. The units of tensile stress A and B are MPa. The membrane property evaluation device 22 calculates the elongation retention rate as A / B × 100 (%). The tensile stress B can also be determined in advance and stored in the membrane property evaluation device 22. In this case, the membrane property evaluation device 22 can calculate A / B × 100 (%) based on the tensile stress A of the hollow fiber membrane taken out from the first modules 21A and 21B. The fractionation retention rate is the removal rate of proteins of a predetermined molecular weight. The fractionation retention rate can be determined in the same way. The first modules 21A and 21B are mounted on the membrane property evaluation device 22, and the removal rate C of proteins of a predetermined molecular weight is determined. Similarly, a new (unused) evaluation filtration membrane device, identical to the first modules 21A and 21B, is mounted on the membrane property evaluation device 22, and the removal rate D of a predetermined molecular weight protein is determined. The units of the removal rates C and D are in percent. Preferably, the predetermined molecular weight is approximately equal to the nominal fractionation molecular weight of the membrane being evaluated. For example, when evaluating a membrane with a fractionation molecular weight of 4000, it is preferable to use a protein with a molecular weight of approximately 4000. The membrane property evaluation device 22 calculates the fractionation retention rate as C / D × 100 (%). The fractionation retention rate D can also be determined in advance and stored in the membrane property evaluation device 22. In this case, the membrane property evaluation device 22 can calculate C / D × 100 (%) based on the removal rate C of the first modules 21A and 21B.When at least one of the elongation retention rate and the fraction retention rate is below a predetermined threshold value, the membrane property evaluation device 22 outputs an evaluation result indicating this and / or a notification prompting replacement of the membrane of the ultrafiltration membrane device 18. The output of the evaluation result and the notification can be performed by any method such as outputting a signal to a control device (not shown) of the ultrapure water production device 1, displaying on the screen of the control device, and the like. From the measurement examples described later, it is preferable that the predetermined threshold value is 85% or less for the elongation retention rate and 70% or less for the fraction retention rate.

[0019] Conventionally, the method of estimating the deterioration state of the membrane filtration device based on water quality is not a method for directly diagnosing whether the membrane filtration device is actually deteriorated. However, even if the number of fine particles in the permeated water or concentrated water of the membrane filtration device is not affected, there is a possibility that the produced wafers may be affected. The reason is that since fine particles with a small particle size tend to have low detection accuracy, it is conceivable that the actual number of fine particles has increased even though there is no change in the measurement result of water quality. Since the membrane property evaluation device 22 directly evaluates the state of the membrane filtration device using physical indicators, it becomes possible to evaluate the deterioration state of the membrane filtration device with higher reliability.

[0020] As described above, since the elongation retention rate and the fraction retention rate are indicators that directly indicate the performance deterioration of the membrane, measuring the elongation retention rate and the fraction retention rate is a highly reliable method. For this reason, the evaluation of the elongation retention rate and the fraction retention rate has been sometimes carried out by membrane manufacturers. However, these evaluations need to be performed by removing the ultrafiltration membrane device 18 from the ultrapure water production device 1, which not only increases the working process but also increases the possibility of foreign matter mixing into the ultrapure water. Moreover, once these evaluations are performed, the membrane cannot be reused, so conventionally, they have been performed only when some problem occurs in the ultrafiltration membrane device 18. That is, although the elongation retention rate and the fraction retention rate are suitable for evaluating the performance deterioration of the membrane with high reliability, they are not suitable for evaluating the performance deterioration of the ultrafiltration membrane device 18 during operation. In the present embodiment, since the elongation retention rate and the fraction retention rate are evaluated for the hollow fiber membranes of the first modules 21A and 21B that simulate the ultrafiltration membrane device 18, it does not affect the operation of the ultrapure water production device 1.

[0021] Addition lines L16 and L17 for adding the evaluation substance are connected to the inlets of the second modules 21C and 21D of the fourth and fifth lines L14 and L15. Addition lines L16 and L17 are equipped with evaluation water storage tanks 23 for storing water mixed with the evaluation substance at a high concentration in ultrapure water, and pumps 24 for transferring this water. Between the confluence of the addition lines L16 and L17 of the fourth and fifth branch lines L14 and L15 and the inlets of the second modules 21C and 21D, first detection devices C3 and C4 for detecting the evaluation substance are provided. Second detection devices C5 and C6 for detecting the evaluation substance are provided at the outlets of the second modules 21C and 21D of the fourth and fifth branch lines L14 and L15. The first and second detection devices C3 to C6 are water quality meters such as particulate meters, and may be water quality meters using the spray drying method described above.

[0022] The particle size of the evaluation substance is not particularly limited, and either fine particles with a small particle size or fine particles with a large particle size can be used. Examples of the evaluation substance include standard substances such as polystyrene (PSL) particles with a particle size of 123 nm and silica nanoparticles (SiO2 particles) with a particle size of 100 nm. These are fine particles with high particle size uniformity and are commercially available. In order to evaluate the performance degradation of the ultrafiltration membrane device 18, it is preferable to use fine particles with a particle size in the nano-order (<10 nm) as the evaluation substance. However, generally, fine particles with a small particle size have low detection efficiency and it is difficult to detect them with high precision. On the other hand, when the membrane breaks or deteriorates, relatively large-particle-size fine particles are also likely to pass through the membrane, so fine particles with a large particle size are also sufficiently practical. In addition, since fine particles with a large particle size can be accurately detected by the first and second detection devices C3 to C6, the particle retention rate of the second modules 21C and 21D can be easily obtained. The particle size of the evaluation substance can be appropriately selected in consideration of these points. The retention rate can be obtained as (N1 - N2) / N1 × 100 (%) where N1 (pieces / mL) is the number of detected fine particles by the first detection devices C3 and C4, and N2 (pieces / mL) is the number of detected fine particles by the second detection devices C5 and C6. As described above, since the ultrafiltration membrane device 18 can also capture organic substances depending on its form, organic substance powder can also be used as the evaluation substance. In this case, a TOC meter can also be used as the first and second detection devices C3 to C6. An example of the evaluation substance is PEG2000 (polyethylene glycol with an average molecular weight of 1850 to 2150 (H(OCH2CH2) n OH)). PEG2000 is one of the protein molecules used when determining the fractional molecular weight of the ultrafiltration membrane.

[0023] The first modules 21A and 21B for which the elongation retention rate and the fraction retention rate were evaluated cannot be reused. Regarding the second modules 21C and 21D, if the input of the evaluation substance is repeated, the membrane will be damaged, so it is difficult to reuse them repeatedly. Therefore, it is preferable to provide a plurality of the first and second modules 21A to 21D in parallel, respectively.

[0024] Since the first and second modules 21A to 21D simulate the ultrafiltration membrane device 18, it is preferable that the degradation of the ultrafiltration membrane device 18 can be accurately evaluated. Ideally, the degradation of the first and second modules 21A to 21D should be at the same level as the degradation of the ultrafiltration membrane device 18, but this may be difficult due to variations in the membrane. Therefore, in reality, it is preferable that the degradation of the first and second modules 21A to 21D be on the safe side compared to the degradation of the ultrafiltration membrane device 18. For this reason, the flow rate of ultrapure water supplied to the first and second modules 21A to 21D can be made higher than the flow rate of ultrapure water supplied to the ultrafiltration membrane device 18. By increasing the flow rate, membrane degradation occurs and progresses more quickly, thus obtaining an effect similar to that of an accelerated test. The flow rate of the first and second modules 21A to 21D can be, for example, 1 to 3 times the flow rate of the ultrafiltration membrane device 18. The flow velocity can be adjusted, for example, by changing the ratio of the number of hollow fiber membranes in the first and second modules 21A to 21D and the ultrafiltration membrane device 18, and the cross-sectional area of ​​the container that fills the hollow fiber membranes. As an alternative to accelerate membrane degradation, for example, a valve can be installed upstream of all branching points of the second to fifth lines L12 to L15 in the first line L11, and the opening and closing of this valve can be repeatedly performed (or the opening degree can be changed). Since pressure fluctuations are applied to the first and second modules 21A to 21D, the degradation of the first and second modules 21A to 21D can be accelerated compared to when ultrapure water is passed through at a constant flow velocity.

[0025] The flow rate of ultrapure water supplied to multiple first modules 21A and 21B can be varied for each first module 21A and 21B. For example, the flow rate of the first module 21A can be set higher than that of the second module 21B. Since the measured values ​​of the first and second water quality meters C1 and C2 are expected to deteriorate sequentially starting from the evaluation filtration membrane device with the highest flow rate (in this case, the first module 21A), it becomes easier to predict the deterioration timing of the ultrafiltration membrane device 18. The flow rate of ultrapure water supplied to multiple second modules 21C and 21D can also be varied for each second module 21C and 21D. For example, the flow rate of ultrapure water supplied to the second module 21C can be set higher than that of ultrapure water supplied to the second module 21D. Since the particulate filter rejection rate is expected to decrease sequentially from the evaluation filtration membrane device with the highest flow rate (in this case, the second module 21C), it becomes easier to predict the degradation period of the ultrafiltration membrane device 18. As a result, the operation and management of the ultrafiltration membrane device 18 becomes easier.

[0026] The performance evaluation of the ultrafiltration membrane device 18 of the ultrapure water production system 1 is performed according to the following procedure. The inlet water of the ultrafiltration membrane device 18 is supplied from the main line L1 of the ultrapure water production system 1 to the first and second modules 21A to 21D connected to the branch lines L11 to L15. The inlet water of the ultrafiltration membrane device 18 is continuously supplied to the first and second modules 21A to 21D during the operation of the ultrapure water production system. The water quality of the outlet water of the first module 21A or 21B is continuously measured online using the first or second water quality meters C1 and C2. However, it is also possible to measure the water quality of the outlet water of the first modules 21A and 21B using both the first and second water quality meters C1 and C2. The elongation retention rate and fractionation retention rate are evaluated at appropriate timings. The timing is not particularly limited, but possible timings include when the total flow rate reaches a predetermined value, or when either the first or second water quality meter C1 or C2 shows an abnormal value. When evaluating the elongation retention rate and fractionation retention rate, the first module 21A or 21B to be evaluated is isolated by the inlet valve V1 or V2, the first modules 21A and 21B are removed from the second or third line L12 or L13, and installed in the membrane property evaluation device 22 for testing. The inlet valve V1 or V2 is kept closed until the ultrafiltration membrane device 18 is replaced. Alternatively, another module may be installed in the second or third line L12 or L13 from which the first modules 21A and 21B were removed.

[0027] The evaluation substance is added to one of the second modules 21C, 21D (here referred to as the second module 21C). When adding the evaluation substance, valve V5 of the addition line L16 connected to the second module 21C being evaluated is opened, and valve V6 of the addition line L17 connected to the second module 21D not being evaluated is closed. The evaluation substance is added at a predetermined timing. Before adding the evaluation substance, the first and second detection devices C3 and C5 corresponding to the second module 21C being evaluated are activated, and the number of particulate matter, etc., is detected by the first and second detection devices C3 and C5. The rejection rate can be determined from the measurement results of the first and second detection devices C3 and C5 as described above. Since the second module 21C gradually deteriorates due to the addition of the evaluation substance, it is preferable not to use it after a predetermined number of additions, and thereafter add the evaluation substance to another second module 21D.

[0028] Either the first module 21A, 21B or the second module 21C, 21D may be omitted, in which case the above evaluation will be performed using only one of the first module 21A, 21B or the second module 21C, 21D. In other words, in this embodiment, the performance of the ultrafiltration membrane device 18 is evaluated by measuring at least one of the physical properties of at least one evaluation filtration membrane device 21 and at least one of the water quality of the treated water from at least one evaluation filtration membrane device 21.

[0029] Next, the elongation retention rate and fractionation retention rate were measured using two hollow fiber membrane modules (first and second hollow fiber membrane modules 31 and 32) (measurement example). The hollow fiber membrane modules 31 and 32 had a membrane area of ​​0.29 m². 2An ultrafiltration membrane module 21XSLP-1036 (manufactured by Asahi Kasei) was used. The first hollow fiber membrane module 31 used a new hollow fiber membrane, while the second hollow fiber membrane module 32 used a new hollow fiber membrane that had been immersed in a 1% H2O2 solution at room temperature for 7 to 14 days. In other words, the second hollow fiber membrane module 32 simulated a deteriorated hollow fiber membrane module. In the second hollow fiber membrane module 32, the elongation retention rate was 87%, and the fractionation retention rate was 71%. From this, it was confirmed that the elongation retention rate and fractionation retention rate decreased in a deteriorated hollow fiber membrane module.

[0030] (Example 1) Next, tests were conducted using the test apparatus shown in Figure 3. The test apparatus corresponds to the ultrapure water production apparatus 1 shown in Figure 1, and the same elements are given the same reference numerals, thus omitting further explanation. The first hollow fiber membrane module 31 and the second hollow fiber membrane module 32, prepared in the same manner as in the measurement example above, were arranged in parallel. Due to the constraints of the test apparatus, the branch line L11 is located between the ion exchange device 15 and the membrane degasser 16, rather than between the membrane degasser 16 and the ultrafiltration membrane device 18, but it is considered that the effect of the difference in branch position is negligible.

[0031] First, a portion of the ultrapure water flowing through the subsystem was supplied to the first hollow fiber membrane module 31 from branch line L11, and the number of particles was measured using particle meter C7. Next, a valve (not shown) was switched to supply a portion of the ultrapure water flowing through the subsystem to the second hollow fiber membrane module 32, and the number of particles was measured using particle meter C7. KANOMAX's STPC3 was used as particle meter C7. This particle meter can detect not only particles but also dissolved components such as organic matter and metals. The particle size categories are 3nm, 9nm, and 15nm, and it detects particles with measurement ranges of 3nm and above, 9nm and above, and 15nm and above, respectively. The flow rate of the ultrapure water flowing through the first and second hollow fiber membrane modules 31 and 32 was 1.5 L / min, the flow velocity was 0.31 (m / h), and the differential pressure between the first hollow fiber membrane module 31 and the second hollow fiber membrane module 32 was 0.09 (MPa) and 0.07 (MPa), respectively.

[0032] The results are shown in Table 1. In the table, the first hollow fiber membrane module 31 is shown as UF#1 and the second hollow fiber membrane module 32 is shown as UF#2. Although there are differences depending on the measurement range, the measured number of particles in the outlet water of UF#2 was 11% higher than the measured number of particles in the outlet water of UF#1 at measurement ranges of 9 nm and above. From this, it was confirmed that the performance degradation of the ultrafiltration membrane device 18 can be estimated by measuring the number of particles in the outlet water of the first modules 21A and 21B using the first and second water quality meters C1 and C2. Furthermore, since the differential pressure at the second hollow fiber membrane module 32 is smaller than the differential pressure at the first hollow fiber membrane module 31, it is considered that the performance degradation of the ultrafiltration membrane device 18 can also be estimated by comparing the differential pressure of the first modules 21A and 21B with the differential pressure of the ultrafiltration membrane device 18.

[0033] [Table 1]

[0034] (Example 2) Next, similar to Example 1, a portion of the ultrapure water flowing through the subsystem was supplied to the first hollow fiber membrane module 31 from branch line L11, while a standard substance was added to the supply water, and the rejection rate of the standard substance in the first hollow fiber membrane module 31 was determined. Then, a valve (not shown) was switched, and a portion of the ultrapure water flowing through the subsystem was supplied to the second hollow fiber membrane module 32, while a standard substance was added to the supply water, and the rejection rate of the standard substance in the second hollow fiber membrane module 32 was determined. PEG2000, PSL particles with a particle size of 123 nm, and SiO2 particles with a particle size of 100 nm were used as the standard substances. When PEG2000 was used, KANOMAX's STPC3 was used as particle meter C7. When PSL particles were used, Rion Co., Ltd.'s liquid particle counter KL-30A (minimum measurable particle size 50 nm) was used as particle meter C7. When SiO2 particles were used, Rion Co., Ltd.'s liquid particle counter KL-27 (minimum measurable particle size 100 nm) was used as particle meter C7. The flow rate, flow velocity, and differential pressure of the ultrapure water flowing through the first and second hollow fiber membrane modules 31 and 32 were the same as in Example 1.

[0035] The results are shown in Table 2. In the table, the first hollow fiber membrane module 31 is shown as UF#1 and the second hollow fiber membrane module 32 is shown as UF#2. When using PSL particles and SiO2 particles, no significant difference in rejection rate was observed between UF#1 and UF#2, but a significant difference was confirmed when using PEG2000. From this, it was confirmed that the performance degradation of the ultrafiltration membrane device 18 can be estimated by measuring the rejection rate of the second modules 21C and 21D using the first and second detection devices C3 to C6.

[0036] [Table 2]

[0037] Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to these. For example, the filtration membrane device to be evaluated may be a microfiltration membrane, a flat membrane, or a pleated membrane. The number of first and second modules is not limited to two, and many more first and second modules may be provided. By providing multiple first and second modules, it becomes possible to perform evaluations with different evaluation periods and evaluation conditions (water flow conditions such as linear velocity) for the first and second modules. Conversely, even if only one first and one second module is provided, it is possible to evaluate the elongation retention rate and fractionation retention rate. In order to miniaturize the first and second modules, it is also possible to use hollow fiber membranes that are shorter in length than the ultrafiltration membrane device 18 but have the same material and pore size. Furthermore, although the embodiments and examples focused on ultrapure water production equipment, the present invention can be suitably applied to pure water production equipment in general, including ultrapure water production equipment. [Explanation of Symbols]

[0038] 1 Ultrapure water production equipment 2. Performance evaluation device 18. Ultramembrane filtration system 21A, 21B First module 21C, 21D Second Module C1, C2: First and second water quality meters C3~C6 First to Fourth Detection Devices L1 Main Line L11~L15 Branch Line L16, L17 Addition Line

Claims

1. A performance evaluation device for a membrane filtration system installed in a pure water production system, A branch line that branches off at the inlet of the membrane filtration device in the line of the pure water production apparatus, It comprises at least one evaluation filtration membrane device connected to the aforementioned branch line, The at least one evaluation filtration membrane device comprises a membrane of the same type as the membrane filtration device, and the membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than the membrane area of ​​the membrane of the membrane filtration device. The at least one evaluation filtration membrane device has at least one first module, The system further comprises a film property evaluation device for evaluating the film properties of at least one of the first modules, The membrane property evaluation device is a performance evaluation device for a membrane filtration apparatus that measures at least one of the elongation retention rate of the yarn constituting the membrane of the at least one first module and the fractionation retention rate of the at least one first module.

2. The performance evaluation device according to claim 1, wherein the membrane property evaluation device outputs a notification prompting the replacement of the membrane of the membrane filtration device when the elongation retention rate becomes 85% or less, or the fractionation retention rate becomes 70% or less.

3. The performance evaluation apparatus according to claim 1, further comprising a water quality meter provided at the outlet of at least one first module of the branch line.

4. A device for evaluating the performance of a membrane filtration device provided in a pure water production device, A branch line that branches off at the inlet of the membrane filtration device in the line of the pure water production apparatus, It comprises at least one evaluation filtration membrane device connected to the aforementioned branch line, The at least one evaluation filtration membrane device comprises a membrane of the same type as the membrane filtration device, and the membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than the membrane area of ​​the membrane of the membrane filtration device. The aforementioned at least one evaluation filtration membrane apparatus has at least one second module, An addition line for adding an evaluation substance is connected to the inlet of at least one second module of the branch line, A performance evaluation device for a membrane filtration apparatus, comprising: a detection device provided at the outlet of at least one second module of the branch line for detecting the substance to be evaluated.

5. The at least one first module is a plurality of first modules installed in parallel, The performance evaluation apparatus according to claim 1, wherein the at least one evaluation filtration membrane apparatus further comprises a plurality of second modules installed in parallel.

6. The at least one second module is a plurality of second modules installed in parallel, The performance evaluation apparatus according to claim 4, wherein the at least one evaluation filtration membrane apparatus further comprises a plurality of first modules installed in parallel.

7. The performance evaluation apparatus according to claim 5, wherein the water flow velocities supplied to the plurality of first modules are different from each other, and the water flow velocities supplied to the plurality of second modules are different from each other.

8. The performance evaluation apparatus according to claim 6, wherein the water flow velocities supplied to the plurality of first modules are different from each other, and the water flow velocities supplied to the plurality of second modules are different from each other.

9. The performance evaluation apparatus according to claim 1, wherein the flow rate of water supplied to at least one evaluation filtration membrane apparatus is higher than the flow rate of water supplied to the membrane filtration apparatus of the pure water production apparatus.

10. A method for evaluating the performance of a membrane filtration system installed in a pure water production system, The inlet water of the membrane filtration device is supplied to at least one evaluation filtration membrane device connected to a branch line that branches off from the line in which the membrane filtration device of the pure water production apparatus is provided, at the inlet of the membrane filtration device. The performance of the membrane filtration device is evaluated by measuring at least one of the physical properties of the at least one evaluation filtration membrane device or the water quality of the treated water from the at least one evaluation filtration membrane device. The at least one evaluation filtration membrane device comprises a membrane of the same type as the membrane filtration device, and the membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than the membrane area of ​​the membrane of the membrane filtration device. The at least one evaluation filtration membrane device has a first module, The system further includes a film property evaluation device for evaluating the film properties of the first module, The membrane property evaluation device measures at least one of the elongation retention rate of the threads constituting the membrane of the first module and the fractionation retention rate of the first module, and is a method for evaluating the performance of a membrane filtration device.

11. A method for evaluating the performance of a membrane filtration device provided in a pure water production apparatus, The inlet water of the membrane filtration device is supplied to at least one evaluation filtration membrane device connected to a branch line that branches off from the line in which the membrane filtration device of the pure water production apparatus is provided, at the inlet of the membrane filtration device. The performance of the membrane filtration device is evaluated by measuring at least one of the physical properties of the at least one evaluation filtration membrane device or the water quality of the treated water from the at least one evaluation filtration membrane device. The at least one evaluation filtration membrane device comprises a membrane of the same type as the membrane filtration device, and the membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than the membrane area of ​​the membrane of the membrane filtration device. The aforementioned at least one evaluation filtration membrane device has a second module, The evaluation substance is added to the branch line from an additive line connected to the inlet of the second module of the branch line, A method for evaluating the performance of a membrane filtration apparatus, comprising detecting the evaluation substance with a detection device provided at the outlet of the second module of the branch line.

12. A pure water production system comprising a membrane filtration device, a line equipped with the membrane filtration device, and a performance evaluation device according to any one of claims 1 to 9.

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