Ion-exchange device and method for controlling ion-exchange device

Abstract

Provided is a non-regenerative ion-exchange device in which water to be treated is passed downward through a packed bed of an ion-exchange resin inside a vessel. The non-regenerative ion-exchange device has a freeboard zone overlying the packed bed, wherein the ion-exchange device is characterized by including a water sampling means for sampling water inside the freeboard zone and a fine-particle counting means for counting the number of fine particles contained in the water sampled by the water sampling means.

Description

Ion exchange device and method for managing the ion exchange device

[0001] The present invention relates to an ion exchange device in which a packed bed of ion exchange resin is formed in a container, and a method for managing the ion exchange device, and more particularly to an ion exchange device and a method for managing the ion exchange device that are suitable for application to an ion exchange device in an ultrapure water manufacturing system.

[0002] In the electronics industry, such as liquid crystal and semiconductor manufacturing, which requires highly pure water and ultrapure water, non-regenerative ion exchange units are often installed at the end of primary water purification systems or in secondary water purification systems to remove trace amounts of ions. Mixed-bed ion exchange resin units are often used as non-regenerative ion exchange resin units, but single-bed and double-bed ion exchange resin units are also used.

[0003] Since non-regenerative ion exchange resin devices are installed upstream of the point of use, if an ion leak occurs from the non-regenerative ion exchange resin device, the operation of the production facility may be stopped. For this reason, non-regenerative ion exchange resin devices have traditionally been replaced early, making it difficult to make full use of the ion exchange capacity of the non-regenerative ion exchange resin device.

[0004] As a countermeasure to this problem, Patent Document 1 describes a method in which a small resin column filled with the same ion exchange resin as the non-regenerative ion exchange resin is installed in a column smaller than the column of the non-regenerative ion exchange resin device in parallel to the non-regenerative ion exchange resin device, the same water to be treated as the water to be treated that is passed through the small resin column, the number of fine particles in the small resin column is measured, and the ion breakthrough time of the non-regenerative ion exchange resin device is predicted based on this number of fine particles and the number of fine particles in the water to be treated.

[0005] Patent Document 2 describes a method for maintaining a reduced number of particles in ultrapure water by measuring the number of particles in the treated water of a non-regenerative mixed-bed ion exchange device using a particle number measuring means, and replacing the non-regenerative mixed-bed ion exchange device when the number of particles exceeds a predetermined value.

[0006] JP 2021-30102 A JP 2019-136628 A

[0007] In a non-regenerative mixed-bed ion exchange unit where the water being treated flows downward, the force of the feedwater flowing into the freeboard section of the vessel causes the ion exchange resin particles in the upper layer of the packed bed to float up into the freeboard section, and the flowing ion exchange resin particles collide with each other, generating fine particles (dust). When such dust generation occurs, even though the number of fine particles in the inflow water of the non-regenerative ion exchange unit is small, the number of fine particles in the treated water (deionized water) increases due to the fine particles generated in the vessel, resulting in fine particle breakthrough through the non-regenerative ion exchange unit in a short period of time.

[0008] An object of the present invention is to provide an ion exchange apparatus capable of predicting an increase in the number of fine particles due to dust generation from ion exchange resin in a non-regenerative mixed-bed ion exchange apparatus, and a method for managing the ion exchange apparatus.

[0009] The present invention provides the following.

[0010] [1] A non-regenerative ion exchange device in which water to be treated flows downward through a packed bed of ion exchange resin in a container, the ion exchange device having a freeboard section above the packed bed, the ion exchange device comprising: a water sampling means for sampling water in the freeboard section; and a particle number measuring means for measuring the number of particles in the water sampled by the water sampling means.

[0011] [2] The ion exchange apparatus according to [1], wherein the water sampling means comprises a strainer disposed in the freeboard section and a pipe for extracting water that has passed through the strainer to the outside of the vessel.

[0012] [3] A method for managing an ion exchange apparatus according to [1] or [2], wherein, when the number of particles in the collected water exceeds a predetermined value, one or more of the following measures are taken: (1) reducing the amount of water passing through; (2) reducing the amount of ion exchange resin packed in the packed bed to lower the level of the top surface of the packed bed; or (3) leveling the top surface of the packed bed if it is not flat.

[0013] [4] The method for managing an ion exchange device according to [1] or [2], wherein an alarm is generated when the number of particles in the collected water exceeds a specified value.

[0014] According to the present invention, by collecting water to be treated from the freeboard section (a void space formed above the ion exchange resin packed bed) in the vessel of the ion exchange device and measuring the number of particles, it is possible to detect an increase in the number of particles due to dust generation from the ion exchange resin, and thereby to predict the breakthrough of particles in the ion exchange device.

[0015] According to one aspect of the present invention, the number of fine particles due to dust generation can be reduced by adjusting the water flow rate or by reducing the amount of ion exchange resin packed in the ion exchange unit based on the measurement results of the number of fine particles in the freeboard section. According to one aspect of the present invention, the number of fine particles due to dust generation can be reduced by flattening the upper surface of the packed bed based on the measurement results of the number of fine particles in the freeboard section, thereby lengthening the fine particle breakthrough time of the ion exchange unit.

[0016] 1A and 1B are schematic vertical cross-sectional views of an ion exchange apparatus for explaining a first embodiment and a second embodiment, respectively;

[0017] An embodiment of the present invention will be described in detail below with reference to Figures 1 and 2. Note that Figures 1 and 2 are merely examples of the present invention, and other embodiments than those shown in the drawings may be used.

[0018] 1 is a schematic vertical cross-sectional view of an ion exchange apparatus 1 for explaining a first embodiment. The ion exchange apparatus 1 includes a vessel 2 and a packed bed 3 of ion exchange resin in the vessel 2. The upper part of the vessel 2 (the part above the packed bed 3) forms a freeboard section F.

[0019] Feedwater flows into the freeboard section F via a water supply pipe 4 and a strainer 5. The feedwater introduced into the freeboard section F flows downward through the packed bed 3, undergoes ion exchange treatment, and reaches the vicinity of the bottom of the packed bed 3. The water then flows into a pipe 7 through a strainer 6 located near the bottom, and is taken out of the ion exchange apparatus 1 as treated water (deionized water).

[0020] A strainer 8 for collecting water is disposed within the freeboard section F, and water that passes through the strainer 8 can be taken out via a pipe 9. A valve 10 is provided on the pipe 9. The valve 10 is open when collecting water and closed when not collecting water. The flow rate of the collected water can be adjusted by adjusting the opening of the valve 10.

[0021] The water collected from the pipe 9 is supplied to an online particle counter (not shown) to monitor the number of particles, or is analyzed and monitored at an analysis center or the like. It is preferable to ensure a water collection flow rate of approximately 0.3 to 2.0 L / min, and it is preferable to use a pipe with an inner diameter of approximately 4 to 10 mm as the pipe 9. The particles are particles with a particle diameter of approximately 0.01 to 0.2 μm.

[0022] There are no particular limitations on the shape of the vessel 2, but a vessel having a substantially cylindrical shape is generally preferred in order to improve pressure resistance and uniformity of the internal flow. Note that corners in the vessel are likely to become stagnation areas.

[0023] In the case of non-regenerative ion exchange devices, mixed-bed ion exchange resins consisting of a mixture of H-type strong cation exchange resins and OH-type strong anion exchange resins are often used. The mixing ratio of cation exchange resin to anion exchange resin is set arbitrarily depending on the feedwater quality and the required treated water quality, but a cation exchange resin / anion exchange resin volume ratio of about 0.2 to 2.0 is generally used.

[0024] The height of the packed bed is about 0.3 to 2.0 m, and the amount of ion exchange resin is 0.02 to 6 m ３ A water flow SV of about 30 to 150 is preferable.

[0025] In order to allow the water to pass through the packed bed almost uniformly without bias, it is preferable that the upper surface of the packed bed is flat.

[0026] The strainer used has openings that do not allow ion exchange resin particles with a particle size of 0.3 to 1.0 mm to pass through.

[0027] 2 is a schematic vertical cross-sectional view of an ion exchange apparatus 1A according to a second embodiment of the present invention. In this ion exchange apparatus 1A, a pipe 7 for removing treated water passes through the bottom of the container 2 and extends downward.

[0028] A pipe 9 for sampling water extends laterally through the side of the container 2. The other configuration is the same as in Figure 1, and the same reference numerals denote the same parts.

[0029] When the amount of ion exchange resin filled in the container 2 is small (several liters to about 100 liters), the embodiment shown in FIG. 1 is often used, and when the amount is large (more than 100 liters), the embodiment shown in FIG. 2 is often used.

[0030] In the case of an ion exchange apparatus with a small amount of ion exchange resin, it is preferable to use the configuration shown in FIG. 1 in which the treated water pipe is inserted to the bottom of the container so that both the water supply pipe and the treated water pipe are taken out from the top, but this is not limitative.

[0031] [Method of Managing Ion Exchange Apparatus] In a method for producing deionized water (ion-exchanged water) using the ion exchange apparatus 1 or 1A shown in Figure 1 or 2, the number of particles in the water sampled from the pipe 8 is monitored. The number of particles may be monitored continuously or intermittently. When monitoring is performed intermittently, it is preferable to monitor the number of particles once a day to once a month, particularly once a day to once a week.

[0032] When the number of particles reaches or exceeds a predetermined value N (for example, a value selected from 10 to 100 particles / mL, particularly 50 to 100 particles / mL), one or more of the following measures are taken: (1) reduce the amount of water passing through; (2) reduce the amount of ion exchange resin packed in the packed bed to lower the level of the top surface of the packed bed; or (3) if the top surface of the packed bed is not flat, smooth it out.

[0033] In the measure (1) above, it is preferable to reduce the amount of water passing through by 10 to 50%, particularly 20 to 30%.

[0034] In the case of the above measure (2), it is preferable to remove the ion exchange resin so that the level of the upper surface of the packed bed is lowered by 10 to 100 mm, particularly 20 to 50 mm. In this way, if the number of fine particles does not decrease sufficiently (for example, does not become equal to or less than the predetermined value N) even after removing a part of the ion exchange resin, the ion exchange resin is removed again to lower the level of the upper surface of the packed bed.

[0035] When taking the measure (3) above, it is preferable to make the top surface of the packed bed flat by shaking (in the case of a small container) or by opening the container and physically leveling it (in the case of a small container or a large container).

[0036] In one embodiment of the present invention, when the number of particles rises to or exceeds a specified value M (e.g., 10 to 100 particles / mL, particularly 50 to 100 particles / mL), and particularly when this state continues for a predetermined time (e.g., 1 to 24 hours, particularly 12 to 24 hours), it is predicted that the number of particles in the deionized water will soon exceed an allowable value, and an alarm is generated. Examples of alarms include the generation of sound, light, etc., and the transmission of a signal to a management center, etc.

[0037] The above-described method for managing an ion exchange device can be carried out not only while the ion exchange device is in use, but also, in the case of a small-container ion exchange device, in which the ion exchange resin is filled in a container in advance at a different location and then the ion exchange device filled with the ion exchange resin is installed in an on-site water treatment device, it can be suitably carried out, for example, when filling the ion exchange resin in a different location before installing the ion exchange device in the on-site water treatment device.

[0038] An ion exchange apparatus according to an embodiment and an example of water flow therethrough will be described below.

[0039] [Ion exchange apparatus 1a for water flow test] The ion exchange apparatus 1a for water flow test has the configuration shown in Figure 1. A container with a diameter of approximately 400 mm and a height of 650 mm was filled with 70 L of a mixed-bed ion exchange resin (KR-UM1, manufactured by Kurita Water Industries Ltd.). The height of the packed bed was approximately 550 mm, and the height of the free board section was approximately 100 mm.

[0040] [Ion exchange apparatus 1b for water flow test] The ion exchange apparatus 1b for water flow test was identical to the ion exchange apparatus 1a for water flow test, except that the amount of ion exchange resin packed in the ion exchange apparatus 1b was 75 L. The height of the packed bed was approximately 600 mm, and the height of the free board section was approximately 50 mm.

[0041] [Particle Counter] A particle monitor for pure water, K-LAMIC-KS (manufactured by Kurita Water Industries Ltd.), was used as the particle counter.

[0042] [Water Supply] Pure water containing less than 5 particles / mL was used as the water supply.

[0043] <Water Flow Example 1 (Using the Ion Exchanger 1a for Water Flow Test)> The ion exchanger 1a for water flow test was ３ The above feed water was passed through the system for more than one year under the conditions of 1000 / h / hour. After one year had passed, the number of particles in the feed water, the freeboard section, and the treated water was measured. The measurement results are shown in Table 1.

[0044] <Water Flow Example 2 (Using Ion Exchanger 1b for Water Flow Test)> For the ion exchanger 1b for water flow test (filling amount of ion exchange resin: 75 L), ３ The number of particles in the feed water, the freeboard section, and the treated water was measured after two months, and the results are shown in Table 1.

[0045] <Water Flow Example 3 (Water Flow with Reduced Flow Rate After Water Flow Example 2)> After two months of water flow in Water Flow Example 2, the water flow rate was reduced to 6 m ３ The flow rate was reduced to 1 / h, and water was passed through in this state for another week, after which the number of particles was measured. The results of measuring the number of particles in the feed water, in the freeboard section, and in the treated water are shown in Table 1.

[0046] <Water Flow Example 4 (Water Flow with Reduced Flow Rate After Water Flow Example 3)> After water flow for one week in Water Flow Example 3, the water flow rate was reduced to 5 m ３ The flow rate was reduced to 1 / h, and water was passed through in this state for another week, after which the number of particles was measured. The results of measuring the number of particles in the feed water, in the freeboard section, and in the treated water are shown in Table 1.

[0047] <Water Flow Example 5 (Water Flowing After Water Flow Example 4, Water Flowing After Changing Ion Exchange Resin Filling Amount and Water Flow Rate)> After Water Flow Example 4, 5 L of ion exchange resin was removed from the container to make the ion exchange resin filling amount 70 L, and the water flow rate was changed to 7 m ３ The flow rate was increased to 1 / h and water was passed through in this state for another week, after which the number of particles was measured. The results of measuring the number of particles in the feed water, in the freeboard section, and in the treated water are shown in Table 1.

[0048]

[0049] [Discussion] (1) Comparing Water Flow Example 1 and Water Flow Example 2, in Water Flow Example 2, the number of particles in the freeboard section and the treated water increased to approximately 2,000 particles / mL and approximately 1,500 particles / mL, respectively.

[0050] Even though the number of particles in the freeboard section was approximately 2,000 / mL, it is estimated that the number of particles in the treated water was small at the beginning of the water flow. After about two months of water flow, the particles had broken through the ion exchange resin, and the number of particles in the freeboard section was approximately the same as the number of particles in the treated water.

[0051] The reason why the number of fine particles in the free board section in Water Flow Example 2 was high at approximately 2,000 particles / mL is thought to be that the amount of ion exchange resin packed was excessive, causing the ion exchange resin to flow within the free board section, resulting in collisions between the ion exchange resin particles and the generation of dust.

[0052] After Water Flow Example 5, the ion exchange resin was extracted and the surface of the ion exchange resin was observed. As a result, numerous fine scratches were observed on the surface of the ion exchange resin sampled from the upper layer of the packed bed, which confirmed that the ion exchange resin particles had collided with each other.

[0053] (2) In Water Flow Example 3, the number of particles in the freeboard section and the treated water was approximately 800 particles / mL and approximately 600 particles / mL, respectively. In Water Flow Example 4, the number of particles in the freeboard section and the treated water was approximately 300 particles / mL and <10 particles / mL, respectively.

[0054] Comparing Water Flow Examples 2, 3, and 4, it was found that the number of fine particles in the freeboard section and in the treated water could be reduced by reducing the water flow rate.

[0055] In addition, 5m ３ In Example 4, where the water flow rate was 10 / h, the number of particulates in the treated water was less than 10 / mL, but the number of particulates in the free board section was approximately 300 / mL, and it is expected that over the long term, particulate breakthrough will progress and the number of particulates in the treated water will become approximately 300 / mL. However, this method is thought to be effective in extending the period during which the number of particulates in the treated water is low, and in suppressing the upper limit of the number of particulates in the treated water to approximately 300 / mL.

[0056] (3) In Example 5, water was passed under the same conditions as in Example 2, except that 5 L of ion exchange resin was withdrawn. The number of particles in the free board section and the treated water was <100 particles / mL and <5 particles / mL, respectively.

[0057] A comparison of Water Flow Examples 2 and 5 confirmed that the number of fine particles in the freeboard section and in the treated water could be reduced by reducing the amount of ion exchange resin packed in and lowering the upper surface of the packed bed. This is thought to be because the flow of ion exchange resin in the freeboard section is suppressed by reducing the amount of ion exchange resin packed in and lowering the upper surface of the packed bed, and by increasing the height of the freeboard section.

[0058] (4) From the above results, it was confirmed that by collecting water from the freeboard section in the vessel of the ion exchange device and measuring and monitoring the number of particles, it is possible to predict the tendency of particle breakthrough more accurately than by measuring and monitoring the number of particles in the water supply to the ion exchange device.

[0059] In addition, by sampling water from inside the freeboard section and measuring the fine particles, it was possible to confirm the improvement effects of adjusting the flow rate and the amount of ion exchange resin filled each time, and it was recognized that by continuing to monitor, the soundness of the ion exchange equipment can be guaranteed.

[0060] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible within the scope of the invention. This application is based on Japanese Patent Application No. 2024-076647 filed on May 9, 2024, the entire contents of which are incorporated by reference.

[0061] 1, 1A Ion exchange device 2 Vessel 3 Packed bed of ion exchange resin 5, 6, 8 Strainer F Freeboard section

Claims

1. A non-regenerative ion exchange device in which water to be treated flows downward through a packed bed of ion exchange resin in a container, the device having a freeboard section above the packed bed, the device comprising: a water sampling means for sampling water in the freeboard section; and a particle number measuring means for measuring the number of particles in the water sampled by the water sampling means.

2. The ion exchange apparatus of claim 1, wherein said water sampling means comprises a strainer disposed within said freeboard section and a pipe for extracting water that has passed through said strainer to the outside of said vessel.

3. A method for managing an ion exchange apparatus according to claim 1 or 2, wherein, when the number of particles in the collected water exceeds a predetermined value, one or more of the following measures are taken: (1) reducing the amount of water passing through; (2) reducing the amount of ion exchange resin packed in to lower the level of the top surface of the packed bed; or (3) leveling the top surface of the packed bed if it is not flat.

4. A method for managing an ion exchange apparatus according to claim 1 or 2, wherein an alarm is generated when the number of particles in the sampled water exceeds a specified value.

5. The method for managing an ion exchange apparatus according to claim 4, wherein the predetermined value is a value selected from the range of 10 to 100 particles / mL.

6. A method for managing an ion exchange apparatus according to claim 1 or 2, wherein, when the number of particles in the sampled water reaches or exceeds a predetermined value, a portion of the ion exchange resin is removed from the container to reduce the amount of ion exchange resin packed in the container, thereby lowering the upper surface level of the packed bed by 10 to 100 mm.

7. The method for managing an ion exchange apparatus according to claim 6, wherein if the number of fine particles does not decrease below the predetermined value even after removing a portion of the ion exchange resin, the ion exchange resin is again removed to lower the upper surface level of the packed bed.

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