Performance evaluation device and performance evaluation method for membrane filtration device of pure water production device, and pure water production system

Abstract

A performance evaluation device (2) for a membrane filtration device is a performance evaluation device for a membrane filtration device of a pure water production device. A performance evaluation device (2) is provided with: branch lines (L11-L15) which extend from a line (L1) of a pure water production device, said line (L1) being provided with a membrane filtration device (18), at an inlet portion of the membrane filtration device (18); and at least one filter membrane device (21A-21D) for evaluation, which is connected to the branch lines (L12-L15). The at least one of the filter membrane devices (21A-21D) for evaluation is provided with a membrane of the same type as the membrane filtration device (18), and the membrane area of the membrane of the at least one of the filter membrane devices (21A-21D) for evaluation is smaller than the membrane area of the membrane of the membrane filtration device (18).

Description

Technical Field

[0001] This application is based on and claims the benefit of priority from Japanese patent application No. 2022-105478 filed on June 30, 2022. The entire contents of the Japanese patent application are incorporated herein by reference.

[0002] The present invention relates to a performance evaluation device for a membrane filtration device of a pure water production device, a pure water production system using the same, and a performance evaluation method for a membrane filtration device of a pure water production device. Background Art

[0003] At the end of the ultrapure water production device (subsystem), a membrane filtration device such as an ultrafiltration membrane device is installed for the purpose of removing 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. In the past, ultrapure water was managed for particles with a particle size of 50nm or more, but in recent years, it has been required to manage small particles with a particle size of 10nm.

[0004] As one of the main reasons for the increase in the number of particles at the end of the subsystem, the degradation and breakage of the membrane filtration device (more precisely, the membrane module in the membrane filtration device) can be cited. The membrane filtration device originally set up to remove particles becomes a source of particles due to degradation and breakage, which may affect the number of particles in the outlet water of the membrane filtration device. Therefore, the management of the membrane filtration device at the end of the subsystem is very important. The following diagnostic method for ultrafiltration membrane is disclosed in Japanese Patent Gazette No. 6450563: the number of coarse particles in the permeate water and concentrated water of the ultrafiltration membrane is measured, and when it exceeds a given threshold, it is judged that the ultrafiltration membrane is degraded. Specifically, the permeate water of the ultrafiltration membrane is sampled, the particles in the sampled water are captured by the membrane filtration device, and the captured particles are observed by a scanning electron microscope (SEM). Summary of the invention

[0005] According to the diagnostic method described in Japanese Patent No. 6450563, it is possible to obtain a sample of particles while continuously operating a pure water production device including an ultrapure water production device. However, since the evaluation of the membrane filtration device depends only on the sampled water, detailed evaluation of the state of the membrane filtration device is limited.

[0006] An object of the present invention is to provide a performance evaluation device for a membrane filtration device of a pure water production device, which can evaluate the performance degradation of the membrane filtration device in more detail while suppressing the influence on the operation of the pure water production device.

[0007] The performance evaluation device of the membrane filtration device of the present invention is a performance evaluation device of the membrane filtration device of the pure water production device. The performance evaluation device comprises: a branch line branched from a pipeline of the pure water production device provided with the membrane filtration device at the inlet portion of the membrane filtration device; and at least one evaluation filtration membrane device connected to the branch line. At least one evaluation filtration membrane device is provided with 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.

[0008] According to the present invention, it is possible to provide a performance evaluation device for a membrane filtration device of a pure water production apparatus, which can evaluate the performance degradation of the membrane filtration device in more detail while suppressing the influence on the operation of the pure water production apparatus.

[0009] The above and other objects, features and advantages of the present application will become more apparent from the detailed description given below with reference to the accompanying drawings which illustrate the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of an ultrapure water production apparatus according to one embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram of a performance evaluation device for an ultrafiltration membrane device.

[0012] Figure 3 This is a schematic diagram of a test device used in Examples. DETAILED DESCRIPTION

[0013] Figure 1 The following is an overview of subsystems of the ultrapure water production apparatus 1 according to one embodiment of the present invention. Figure 2 yes Figure 1 The enlarged view of the A part of the performance evaluation device 2 shows the outline of the performance evaluation device 2. The subsystem is a system for producing ultrapure water, which is produced from pure water produced by the primary pure water system (not shown) and supplied to the point of use POU. The subsystem is also called a secondary pure water system. Regarding the following description of the ultrapure water production device 1, unless otherwise specified, the subsystem is the object, and there is a case where the subsystem is referred to as the ultrapure water production device 1. The ultrapure water production device 1 is used in the manufacturing process of electronic components such as semiconductors.

[0014] The subsystem of the ultrapure water production device 1 includes: a main line L1 connected to the point of use POU; a plurality of water treatment devices, which are arranged on the main line L1 and are used to produce ultrapure water; and a return line L2, which returns the ultrapure water that is not used (more precisely, not used) at the point of use POU to the main line L1. On the main line L1, the pure water tank 11, the pure water supply pump 12, the heat exchanger 13, the ultraviolet oxidation device 14, the ion exchange device 15, the membrane degassing device 16, the booster pump 17, and the ultrafiltration membrane device 18 are arranged in series along the flow direction D of the pure water in the order described. The ultraviolet oxidation device 14, the ion exchange device 15, the membrane degassing device 16, and the ultrafiltration membrane device 18 are examples of the above-mentioned water treatment devices. A plurality of supply lines L3 for supplying ultrapure water to each point of use POU branch out from the main line L1. A plurality of recovery lines L4 for recovering the ultrapure water that has not been used at each point of use POU merge with the return line L2. The return line L2 is connected to the pure water tank 11. The ultrapure water flowing 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.

[0015] Pure water produced by a primary pure water system is stored in the pure water tank 11. 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 ultraviolet rays to the pure water whose temperature has been adjusted by the heat exchanger 13, and decomposes the organic matter contained in the pure water. The ion exchange device 15 removes the ion components in the pure water. The ion exchange device 15 is a non-regenerative cylinder polisher in which a mixed bed is filled with cation exchange resin and anion exchange resin. The membrane degassing device 16 degasses the pure water, that is, removes the dissolved oxygen and carbon dioxide contained in the pure water. The booster pump 17 is provided to pressurize the pure water, for example, when the point of use POU is set at a high place. The booster pump 17 can be omitted according to the position of the point of use POU. The ultrafiltration membrane device 18 finally removes the particles contained in the pure water. The ultrafiltration membrane device 18 has a hollow fiber membrane module filled with hollow fiber membranes. Compared with flat membranes and pleated membranes, hollow fiber membranes can increase the packing density of the filter membrane module, thereby increasing the amount of water permeating each filter membrane module. In addition, the hollow fiber membrane module is easy to maintain a high degree of cleanliness, and can be shipped, installed in the ultrapure water production device 1, and replaced on site while maintaining a high degree of cleanliness. As hollow fiber membrane modules, there are modules using polysulfone membranes with a molecular weight cutoff of about 4000 to 6000, such as OLT-6036H made by Asahi Kasei and NTU-3306-K6R made by Nitto Denko (both with a molecular weight cutoff of 6000). It should be noted that the molecular weight cutoff is generally the approximate molecular weight at which more than 90% of spherical solutes (proteins) can be retained in the membrane.

[0016] The ultrapure water production device 1 includes a performance evaluation device 2 for evaluating the performance (deterioration degree) of the ultrafiltration membrane device 18. The performance evaluation device 2 includes: branch lines L11 to L15 branched from the main line L1 at the inlet of the ultrafiltration membrane device 18; and at least one evaluation filter membrane device 21 connected to the branch lines L11 to L15, and in this embodiment, includes two first modules (first evaluation filter membrane devices) 21A and 21B and two second modules (second evaluation filter membrane devices) 21C and 21D. The branch lines L11 to L15 include: a first line L11 connected to the main line L1; and second to fifth lines L12 to L15 branched from the first line L11, the two first modules 21A and 21B are respectively provided in the second line and the third line L12 and L13, and the two second modules 21C and 21D are respectively provided in the fourth line and the fifth line L14 and L15. It should be noted that the branch lines L11 to L15 (first line L11) are preferably 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 degassing device 16 and the ultrafiltration membrane device 18 (the inlet of the ultrafiltration membrane device 18), but as long as the number of particles does not change significantly, they can also be provided on the upstream side of the closest water treatment device. For example, as in the embodiment, the branch lines L11 to L15 can be branched from between the ion exchange device 15 and the membrane degassing device 16. Alternatively, the ion exchange device 15 can be provided between the membrane degassing device 16 and the ultrafiltration membrane device 18, and the branch lines L11 to L15 can be branched from between the ion exchange device 15 and the ultrafiltration membrane device 18.

[0017] The first module 21A, 21B and the second module 21C, 21D are provided with the same type of membrane as the ultrafiltration membrane device 18. The same type of membrane refers to a membrane having the same material, pore size, and size (inner diameter and outer diameter of the hollow fiber, length of the hollow fiber) and having the same filtering performance, but also includes membranes having similar materials, pore sizes, and sizes and having equivalent filtering performance. In the present embodiment, the first module and the second module 21A to 21D and the ultrafiltration membrane device 18 are evaluation filtration membrane devices in which a plurality of hollow fiber membranes are filled in a container, and the material, pore size, and size of the hollow fiber membranes are common to the first module and the second module 21A to 21D and the ultrafiltration membrane device 18. However, the number of hollow fiber membranes in each of the first module and the second module 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 of the first module and the second module 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 of the ultrafiltration membrane device 18. That is, the first module and the second module 21A to 21D are small evaluation filtration membrane devices that imitate the ultrafiltration membrane device 18. The membrane areas of the hollow fiber membranes of the first module and the second module 21A to 21D are the same, but may be different from each other.

[0018] The first water quality meter C1 and the second water quality meter C2 are provided at the outlet of the first modules 21A and 21B of the second pipeline and the third pipeline L12 and L13. The first water quality meter C1 and the second water quality meter C2 are particle meters. TOC (total organic carbon) can be measured, and the concentration of dissolved substances such as metals and organic matter can also be measured instead of measuring particles. As described later, the first modules 21A and 21B are provided to estimate the degradation of the ultrafiltration membrane device 18, so the measurement object is not limited as long as it can be captured by the ultrafiltration membrane device 18. The ultrafiltration membrane device 18 is basically used to capture particles, but if dissolved substances such as organic matter and metals are in granular or colloidal form, the ultrafiltration membrane device 18 also has the ability to capture them. Therefore, the first water quality meter C1 and the second water quality meter C2 can be water quality meters that measure at least one of the number of particles, TOC, and metal concentration.

[0019] As the first water quality meter C1 and the second water quality meter C2, for example, a water quality meter using a spray drying method (such as STPC3 of KANOMAX Company) is cited. The water quality meter has a spray section, an evaporation / drying section and a detection section. The spray section samples and sprays ultrapure water of the measurement object. The evaporation / drying section removes large droplets from the droplets generated by spraying, and heats and evaporates the remaining fine droplets. Particles present in the ultrapure water and particles formed by dissolving non-volatile residues form aerosols. The evaporation / drying section further allows the aerosol to pass through a quasi-permeable membrane to remove moisture. The detection section uses a differential electrostatic classifier to classify the precipitated aerosol according to each size, and uses a condensation particle counter to measure the number concentration of the classified particles. The particle concentration in the ultrapure water is obtained by multiplying the obtained measured value by a pre-corrected coefficient. This method has the following advantages: in principle, it can measure particles with a particle size of about 2.5nm, which is the detection limit of the condensation particle counter, and the measurement results are not affected by the refractive index and shape of the particles.

[0020] In the past, a water quality meter such as a particle meter was installed between the ultrafiltration membrane device 18 and the point of use POU, but it was difficult to judge the deterioration of the ultrafiltration membrane device 18 by this alone. Therefore, in the past, in order to judge the deterioration of the ultrafiltration membrane device 18, a direct detection method was used to sample the permeate water on the outlet side of the ultrafiltration membrane device 18 or the concentrated water in the inlet side space inside the ultrafiltration membrane device 18 and observe it using SEM. However, this method takes a long time to sample and is difficult to measure online. The first water quality meter C1 and the second water quality meter C2 have higher particle detection accuracy than the particle meter installed between the ultrafiltration membrane device 18 and the point of use POU, and the number of particles in the outlet water of the first module 21A and 21B is measured online, so the signs and degree of deterioration of the first module 21A and 21B can be quickly grasped, and the signs and degree of deterioration of the ultrafiltration membrane device 18 as a result. In addition, by using it together with the water quality meter installed between the ultrafiltration membrane device 18 and the point of use POU, a more reliable evaluation can be performed.

[0021] The performance evaluation device 2 has 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 physical properties of the membrane, for example, measures and evaluates the elongation retention rate and the interception retention rate of the hollow fiber. In addition, these measured values ​​and evaluation results can also be output. In the present invention, at least one of the elongation retention rate and the interception retention rate of the hollow fiber constituting the membrane of the first modules 21A and 21B is measured, and preferably both are measured. The membrane property evaluation device 22 is a device independent of the first modules 21A and 21B. The elongation retention rate is calculated as follows. Take out a hollow fiber membrane from the first modules 21A and 21B, install it in the membrane property evaluation device 22, apply tensile stress until it breaks, and calculate the tensile stress A at the time of breakage. Similarly, a new (before use) hollow fiber membrane identical to the hollow fiber membrane filled in the first modules 21A and 21B is installed in 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 calculated. The unit of tensile stress A and B is MPa. The membrane property evaluation device 22 calculates the elongation retention rate as A / B×100 (%). The tensile stress B can also be calculated 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 retention rate is the removal rate of proteins of a given molecular weight. The retention rate can also be calculated in the same way. The first modules 21A and 21B are installed on the membrane property evaluation device 22, and the removal rate C of proteins of a given molecular weight is calculated. Similarly, a new (before use) evaluation filtration membrane device identical to the first modules 21A and 21B is installed in the membrane property evaluation device 22, and the removal rate D of a protein of a given molecular weight is obtained. The units of the removal rates C and D are %. The given molecular weight is preferably roughly consistent with the nominal molecular weight cutoff of the membrane to be evaluated. For example, in the case of evaluating a membrane with a molecular weight cutoff of 4000, it is preferred to use a protein with a molecular weight of about 4000. The membrane property evaluation device 22 calculates the cutoff retention rate as C / D×100 (%). The cutoff retention rate D can also be obtained 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 cutoff retention rate becomes below a given threshold, the membrane property evaluation device 22 outputs an evaluation result indicating the situation and / or a notification urging the replacement of the membrane of the ultrafiltration membrane device 18. The output of the evaluation results and notifications 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 it on a screen of the control device, etc. According to the measurement example described later, the given threshold is preferably 85% or less in terms of elongation retention and 70% or less in terms of interception retention.

[0022] The method of estimating the deterioration state of the membrane filter device based on the water quality in the past is not actually a method of directly diagnosing whether the membrane filter device is deteriorated. However, even if it does not affect the number of particles in the permeated water and concentrated water of the membrane filter device, it is possible to affect the manufactured wafers. As a reason for this, particles with small particle sizes tend to have low detection accuracy, so it is believed that even if the measurement results of the water quality do not change, the number of particles actually increases. The membrane physical property evaluation device 22 directly evaluates the state of the membrane filter device with physical indicators, so it can evaluate the deterioration state of the membrane filter device with higher reliability.

[0023] In this way, the elongation retention rate and the interception retention rate are indicators that directly represent the performance degradation of the membrane, so measuring the elongation retention rate and the interception retention rate is a method with high reliability. Therefore, the evaluation of the elongation retention rate and the interception retention rate has been sometimes implemented by membrane manufacturers so far. However, these evaluations need to remove the ultrafiltration membrane device 18 from the ultrapure water manufacturing device 1, not only the operating process increases, but also the possibility of foreign matter mixed into the ultrapure water increases. Moreover, if these evaluations are implemented, the membrane can no longer be used, so in the past, it was only implemented when some undesirable conditions occurred in the ultrafiltration membrane device 18. That is, the elongation retention rate and the interception retention rate are suitable for evaluating the performance degradation of the membrane with high reliability, but on the other hand, they are not suitable for evaluating the performance degradation of the ultrafiltration membrane device 18 in operation. In the present embodiment, the elongation retention rate and the interception retention rate are evaluated with the hollow fiber membrane of the first module 21A, 21B simulating the ultrafiltration membrane device 18 as the object, so that the operation of the ultrapure water manufacturing device 1 will not be affected.

[0024] Addition lines L16 and L17 for adding evaluation substances are connected to the inlet of the second modules 21C and 21D of the fourth and fifth pipelines L14 and L15. An evaluation water storage tank 23 is provided in the addition lines L16 and L17, which stores water obtained by mixing evaluation substances with ultrapure water at a high concentration; and a pump 24 is provided to transport the water. First detection devices C3 and C4 for detecting evaluation substances are provided between the confluence of the addition lines L16 and L17 of the fourth branch pipeline L14 and the fifth branch pipeline L15 and the inlet of the second modules 21C and 21D. Second detection devices C5 and C6 for detecting evaluation substances are provided at the outlet of the second modules 21C and 21D of the fourth branch pipeline L14 and the fifth branch pipeline L15. The first detection device and the second detection devices C3 to C6 are water quality meters such as a particle meter, and may also be water quality meters using the above-mentioned spray drying method.

[0025] The particle size of the evaluation material is not particularly limited, and particles with small particle size and particles with large particle size can be used. As examples of evaluation materials, standard materials such as polystyrene (PSL) particles with a particle size of 123nm and silica nanoparticles (SiO2 particles) with a particle size of 100nm are cited. They are commercially available particles with high uniformity of particle size. In order to evaluate the performance degradation of the ultrafiltration membrane device 18, it is preferred to use particles with a particle size of nanometers (<10nm) as the evaluation material, but the detection efficiency of particles with small particle size is generally low, and it is difficult to detect them with high precision. On the other hand, when the membrane breaks or deteriorates, particles with larger particle size are also likely to pass through the membrane, so even particles with large particle size are very practical. In addition, particles with large particle size can be detected with high precision by the first detection device and the second detection device C3~C6, so the rejection rate of particles in the second module 21C and 21D can be easily obtained. The particle size of the evaluation material can be appropriately selected based on these aspects. If the number of detected particles in the first detection devices C3 and C4 is set to N1 (pieces / mL), and the number of detected particles in the second detection devices C5 and C6 is set to N2 (pieces / mL), the rejection rate can be calculated as (N1-N2) / N1×100 (%). As mentioned above, the ultrafiltration membrane device 18 can also capture organic matter according to its form, so the powder of organic matter can also be used as an evaluation substance. In this case, a TOC meter can also be used as the first and second detection devices C3 to C6. As an example of an evaluation substance, PEG2000 (polyethylene glycol (H(OCH2CH2) with an average molecular weight of 1850 to 2150) is cited. n OH)). PEG2000 is one of the protein molecules used to determine the molecular weight cutoff of ultrafiltration membranes.

[0026] The first modules 21A and 21B that have been evaluated for elongation retention and interception retention cannot be reused. The second modules 21C and 21D are also difficult to reuse because the membranes are damaged if the evaluation substances are repeatedly added. Therefore, it is preferred that a plurality of first modules and second modules 21A to 21D are arranged in parallel.

[0027] The first module and the second module 21A to 21D simulate the ultrafiltration membrane device 18, so it is preferred that the degradation of the ultrafiltration membrane device 18 can be faithfully evaluated. Ideally, the degradation of the first module and the second module 21A to 21D is preferably the same as the degradation of the ultrafiltration membrane device 18, but there are cases where it is difficult due to the deviation of the membrane. Therefore, in reality, it is preferred that the degradation of the first module and the second module 21A to 21D is on the safe side relative to the degradation of the ultrafiltration membrane device 18. Therefore, the flow rate of the ultrapure water supplied to the first module and the second module 21A to 21D can be higher than the flow rate of the ultrapure water supplied to the ultrafiltration membrane device 18. By increasing the flow rate, the degradation of the membrane occurs and develops faster, so the same effect as the accelerated test is obtained. The flow rate of the first module and the second module 21A to 21D can be set to 1 to 3 times the flow rate of the ultrafiltration membrane device 18, for example. The flow rate can be adjusted, for example, by changing the ratio of the number of hollow fiber membranes in the first module and the second module 21A to 21D and the ultrafiltration membrane device 18 to the cross-sectional area of ​​the container filled with the hollow fiber membranes. As an alternative to promoting the degradation of the membrane, for example, a valve can be provided at the upstream side of all the branches of the second line to the fifth line L12 to L15 of the first line L11, and the valve can be repeatedly opened and closed (or the opening degree can be changed). Since the pressure fluctuation is applied to the first module and the second module 21A to 21D, the degradation of the first module and the second module 21A to 21D can be promoted compared with the case where ultrapure water is passed at a constant flow rate.

[0028] The flow rate of ultrapure water supplied to the plurality of first modules 21A and 21B can be changed for each first module 21A and 21B. For example, the flow rate of the first module 21A can be made higher than the flow rate of the second module 21B. It is expected that the measured values ​​of the first water quality meter C1 and the second water quality meter C2 will deteriorate in sequence from the evaluation filter membrane device with a high flow rate (in this case, the first module 21A), so it is easy to make a prediction of the deterioration period of the ultrafiltration membrane device 18. The flow rate of ultrapure water supplied to the plurality of second modules 21C and 21D can also be changed for each second module 21C and 21D. For example, the flow rate of ultrapure water supplied to the second module 21C can be made higher than the flow rate of ultrapure water supplied to the second module 21D. It is expected that the rejection rate of particles will decrease in sequence from the evaluation filter membrane device with a high flow rate (in this case, the second module 21C), so it is easy to make a prediction of the deterioration period of the ultrafiltration membrane device 18. As a result, the operation and management of the ultrafiltration membrane device 18 becomes easy.

[0029] The performance evaluation of the ultrafiltration membrane device 18 of the ultrapure water manufacturing device 1 is carried out according to the following steps. The inlet water of the ultrafiltration membrane device 18 is supplied from the main line L1 of the ultrapure water manufacturing device 1 to the first module and the second module 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 module and the second module 21A to 21D during the operation of the ultrapure water manufacturing device. The water quality of the outlet water of the first module 21A or 21B is continuously measured online using the first water quality meter C1 or the second water quality meter C2. However, it is also possible to use both the first water quality meter C1 and the second water quality meter C2 to measure the water quality of the outlet water of each of the first modules 21A and 21B. The evaluation of the elongation retention rate and the interception retention rate is implemented at an appropriate timing. The timing is not particularly limited, but it is considered that when the total flow rate reaches a given value, when any of the first or second water quality meters C1 and C2 shows an abnormal value, etc. When evaluating the elongation retention rate and the interception retention rate, the first module 21A or 21B of the evaluation object is isolated by the inlet valve V1 or V2, and the first module 21A, 21B is removed from the second pipeline L12 or the third pipeline L13, and installed in the membrane property evaluation device 22 for testing. The inlet valve V1 or V2 remains closed until the ultrafiltration membrane device 18 is replaced. Alternatively, other modules may be installed on the second pipeline L12 or the third pipeline L13 after the first modules 21A, 21B are removed.

[0030] The addition of the evaluation substance is carried out with one second module 21C, 21D (here, the second module 21C) as the object. When adding the evaluation substance, open the valve V5 of the addition pipeline L16 connected to the second module 21C of the evaluation object, and close the valve V6 of the addition pipeline L17 connected to the second module 21D outside the evaluation object. The addition of the evaluation substance is implemented at a given timing. Before adding the evaluation substance, start the first detection device C3 and the second detection device C5 corresponding to the second module 21C of the evaluation object, and detect the number of particles and the like by the first detection device C3 and the second detection device C5. The blocking rate can be calculated as described above based on the measurement results of the first detection device C3 and the second detection device C5. The second module 21C gradually deteriorates due to the addition of the evaluation substance, so it is preferably not used after a given number of additions, and then the evaluation substance is added to other second modules 21D.

[0031] It is also possible to omit any one of the first modules 21A, 21B and the second modules 21C, 21D, in which case only the first modules 21A, 21B and the second modules 21C, 21D are used to perform the above-mentioned evaluation. That is, 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 the water quality of the treated water of at least one evaluation filtration membrane device 21.

[0032] Next, two hollow fiber membrane modules (the first hollow fiber membrane module 31 and the second hollow fiber membrane module 32) were used to measure the elongation retention rate and the interception retention rate (measurement example). As the hollow fiber membrane modules 31 and 32, the membrane area used was 0.29 m 2 The ultrafiltration membrane module 21XSLP-1036 (manufactured by Asahi Kasei) is used. The first hollow fiber membrane module 31 uses a new hollow fiber membrane, and the second hollow fiber membrane module 32 uses a hollow fiber membrane module made by immersing a new hollow fiber membrane in a 1% H2O2 solution at room temperature for 7 to 14 days. That is, the second hollow fiber membrane module 32 simulates a deteriorated hollow fiber membrane module. In the second hollow fiber membrane module 32, the elongation retention rate is 87% and the interception retention rate is 71%. Therefore, it is confirmed that the elongation retention rate and the interception retention rate of the deteriorated hollow fiber membrane module are reduced.

[0033] (Example 1) Next, use Figure 3 The test device is shown in the test. Figure 1 The same elements are marked with the same reference numerals and the description is omitted. The first hollow fiber membrane module 31 and the second hollow fiber membrane module 32 prepared by the same method as the above-mentioned measurement example are arranged in parallel. According to the situation of the test device, the branch line L11 is not arranged between the membrane degassing device 16 and the ultrafiltration membrane device 18, but is arranged between the ion exchange device 15 and the membrane degassing device 16, but it is believed that there is almost no influence caused by the difference in the branch position.

[0034] First, a portion of the ultrapure water flowing in the subsystem is supplied from the branch line L11 to the first hollow fiber membrane module 31, and the number of particles is measured with a particle meter C7. Next, a valve is switched (not shown), and a portion of the ultrapure water flowing in the subsystem is supplied to the second hollow fiber membrane module 32, and the number of particles is measured with a particle meter C7. As the particle meter C7, STPC3 of KANOMAX is used. This particle meter can detect not only particles, but also dissolved components such as organic matter and metals. As a particle size classification, there are 3nm, 9nm, and 15nm, and the particles with a measurement range of 3nm or more, 9nm or more, and 15nm or more are detected respectively. The flow rate of ultrapure water flowing in the first hollow fiber membrane module 31 and the second hollow fiber membrane module 32 is 1.5L / mim, the flow rate is 0.31 (m / h), and the pressure difference in the first hollow fiber membrane module 31 and the second hollow fiber membrane module 32 is 0.09 (MPa) and 0.07 (MPa), respectively.

[0035] The results are shown in Table 1. In the table, the first hollow fiber membrane module 31 is represented as UF#1, and the second hollow fiber membrane module 32 is represented as UF#2. Although there are differences depending on the measurement range, the measured value of the number of particles in the outlet water of UF#2 is 11% greater than the measured value of the number of particles in the outlet water of UF#1 in the measurement range above 9nm. Thus, it was confirmed that the performance degradation of the ultrafiltration membrane device 18 can be inferred by measuring the number of particles in the outlet water of the first module 21A and 21B using the first water quality meter C1 and the second water quality meter C2. In addition, the pressure difference in the second hollow fiber membrane module 32 is smaller than the pressure difference in the first hollow fiber membrane module 31, so it is believed that the performance degradation of the ultrafiltration membrane device 18 can also be inferred by comparing the pressure difference between the first modules 21A and 21B with the pressure difference of the ultrafiltration membrane device 18.

[0036] [Table 1]

[0037] (Example 2) Next, in the same manner as in Example 1, a portion of the ultrapure water flowing in the subsystem is supplied from the branch line L11 to the first hollow fiber membrane module 31, and a standard substance is added to the supply water, and the rejection rate of the standard substance in the first hollow fiber membrane module 31 is obtained. Next, a valve is switched (not shown), and a portion of the ultrapure water flowing in the subsystem is supplied to the second hollow fiber membrane module 32, and a standard substance is added to the supply water, and the rejection rate of the standard substance in the second hollow fiber membrane module 32 is obtained. As standard substances, PEG2000, PSL particles with a particle size of 123nm, and SiO2 particles with a particle size of 100nm are used. When PEG2000 is used, STPC3 of KANOMAX is used as the particle meter C7. When PSL particles are used, the liquid particle counter KL-30A (minimum measurable particle size 50nm) of RION Corporation is used as the particle meter C7. When SiO2 particles are used, a liquid particle counter KL-27 (minimum measurable particle size 100 nm) manufactured by RION Corporation is used as the particle counter C7. The flow rate, flow velocity, and pressure difference of ultrapure water flowing through the first hollow fiber membrane module 31 and the second hollow fiber membrane module 32 are the same as those in Example 1.

[0038] The results are shown in Table 2. In the table, the first hollow fiber membrane module 31 is represented as UF#1, and the second hollow fiber membrane module 32 is represented as UF#2. When PSL particles and SiO2 particles are used, no significant difference in rejection is found between UF#1 and UF#2, but when PEG2000 is used, a significant difference is confirmed. Thus, it is confirmed that by measuring the rejection of the second modules 21C and 21D using the first detection device and the second detection devices C3 to C6, the performance degradation of the ultrafiltration membrane device 18 can be inferred.

[0039] [Table 2]

[0040] The present invention has been described above through the embodiments and examples, but the present invention is not limited thereto. For example, the filter membrane device of the evaluation object may be a precision filtration membrane, or a flat membrane or a pleated membrane. The number of the first module and the second module is not limited to two, and more first modules and second modules may be provided. By respectively providing a plurality of first modules and second modules, it is possible to perform an evaluation in which the evaluation period and evaluation conditions (water flow conditions such as linear velocity) of the first module and the second module are changed. On the contrary, even if only one first module and one second module are provided respectively, the elongation retention rate and the interception retention rate can be evaluated. In order to miniaturize the first module and the second module, a hollow fiber membrane having the same material and pore size and a shorter length than the ultrafiltration membrane device 18 may also be used. In addition, although the ultrapure water manufacturing device is used as the object in the embodiments and examples, the present invention can be applied to all pure water manufacturing devices including ultrapure water manufacturing devices.

[0041] Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made without departing from the spirit or scope of the claims.

[0042] Description of Reference Numerals 1 Ultrapure water production device 2 Performance evaluation device 18 Ultrafiltration membrane filtration device 21A, 21B Module 1 21C, 21D Module 2 C1, C2 First water quality meter, second water quality meter C3~C6 First detection device~Fourth detection device L1 main line L11~L15 branch pipeline L16, L17 added pipelines.

Claims

1. A performance evaluation device for a membrane filtration device, wherein the membrane filtration device is a device provided in a pure water production device, and the performance evaluation device for the membrane filtration device comprises: a branch line branching out from an inlet portion of the membrane filtration device in a line of the pure water production device in which the membrane filtration device is provided; and at least one evaluation filtration membrane device connected to the branch pipeline, The at least one evaluation filtration membrane device includes a membrane of the same type as that of the membrane filtration device, and a membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than a membrane area of ​​a membrane of the membrane filtration device.

2. The performance evaluation device according to claim 1, wherein: The at least one evaluation filter membrane device comprises a first module, The performance evaluation device further comprises a membrane property evaluation device for evaluating the membrane property of the first module. The membrane property evaluation device measures at least one of an elongation retention rate of fibers constituting the membrane of the first module and a rejection retention rate of the first module.

3. The performance evaluation device according to claim 2, wherein: When the elongation retention rate is 85% or less or the rejection retention rate is 70% or less, the membrane property evaluation device outputs a notification for urging replacement of the membrane of the membrane filtration device.

4. The performance evaluation device according to claim 2 or 3, wherein: The performance evaluation device includes a water quality meter provided at an outlet portion of the first module of the branch line.

5. The performance evaluation device according to any one of claims 1 to 4, wherein: The at least one evaluation filter membrane device has a second module, The performance evaluation device comprises: an addition line connected to the inlet of the second module of the branch line and for adding an evaluation substance; as well as A detection device is provided at an outlet portion of the second module of the branch line and detects the evaluation substance.

6. The performance evaluation device according to any one of claims 1 to 4, wherein: The at least one evaluation filtration membrane device includes a plurality of first modules arranged in parallel and a plurality of second modules arranged in parallel.

7. The performance evaluation device according to claim 6, wherein: The flow rates of water supplied to the plurality of first modules are different from each other, and the flow rates of water supplied to the plurality of second modules are different from each other.

8. The performance evaluation device according to any one of claims 1 to 7, wherein: The flow rate of water supplied to the at least one evaluation filtration membrane device is higher than the flow rate of water supplied to the membrane filtration device of the pure water production device.

9. A method for evaluating the performance of a membrane filtration device, wherein the membrane filtration device is a device provided in a pure water production device, and the method for evaluating the performance of the membrane filtration device comprises the following steps: The inlet water of the membrane filtration device is supplied from the pipeline of the pure water production device provided with the membrane filtration device to at least one evaluation filtration membrane device, and the at least one evaluation filtration membrane device is connected to a branch pipeline branched from the inlet part 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 and the water quality of the treated water of the at least one evaluation filtration membrane device. The at least one evaluation filtration membrane device includes a membrane of the same type as that of the membrane filtration device, and a membrane area of ​​the membrane of the at least one evaluation filtration membrane device is smaller than a membrane area of ​​a membrane of the membrane filtration device. 10 . A pure water production system comprising: a membrane filtration device, a pipeline in which the membrane filtration device is installed, and the performance evaluation device according to any one of claims 1 to 8.

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