Ion exchange equipment and ultrapure water production equipment

Abstract

To provide an ion exchange apparatus that minimizes elution of metal components.SOLUTION: An ion exchange apparatus 1 that includes a container 10 filled with ion exchange resin 2, an outlet channel 13a, which is connected to an opening 13b formed in the bottom 4 of the container 10 and through which water treated with the ion exchange resin 2 flows, and a screen 6 provided at the opening 13b to prevent the ion exchange resin 2 from flowing out of the container 10 into the outlet channel 13a, wherein each of a liquid-contacting portion, which contacts with the treated water, of the outlet channel 13a and a liquid-contacting portion, which contacts with the treated water, of the screen 6 is made of a non-metal material or a metal material substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ion exchange device and an ultrapure water production device. [Background technology]

[0002] In the manufacturing processes of semiconductor devices and liquid crystal devices, ultrapure water, from which impurities have been highly removed, is used for various purposes, such as cleaning. Even trace amounts of metal components contained in ultrapure water can significantly affect device characteristics, so strict control of their concentration is required. In recent years, with the rapid increase in integration and miniaturization of semiconductor devices, requirements for metal concentrations in ultrapure water have become increasingly stringent, resulting in the demand for ultrapure water with metal concentrations at the pg / L level. Ultrapure water is generally produced by sequentially treating raw water (e.g., river water, groundwater, industrial water) through a pretreatment system, a primary pure water system, and a secondary pure water system (subsystem). However, it is known that metal components leach from the piping and pumps used during the manufacturing process. Therefore, several proposals have been made to minimize the impact of metal leachate in such ultrapure water production systems (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-154713 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-224489 Summary of the Invention [Problem to be solved by the invention]

[0004] Some of the above-mentioned subsystems include an ion exchange resin tower (ion exchange device) filled with ion exchange resin. By installing such an ion exchange resin tower, for example, at the most downstream position of the subsystem, it is possible to prevent the influence of metal components eluted upstream from appearing on the quality of the ultrapure water. However, it is known that metal components can be eluted from the ion exchange resin tower itself. Therefore, in order to meet the recent strict requirements for metal concentrations in ultrapure water, it is necessary to minimize the elution of metal components from the ion exchange resin tower.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an ion exchange apparatus and an ultrapure water production apparatus that minimize the elution of metal components. [Means for solving the problem]

[0006] In order to achieve the above object, the ion exchange device of the present invention comprises a container filled with an ion exchange resin, and an opening formed in the bottom surface of the container. Through the bottom of the container The container has an outlet flow path that communicates with the container and through which treated water treated with ion exchange resin flows, and a screen that is provided at the opening and prevents the ion exchange resin from flowing out of the container to the outlet flow path, and the portion of the outlet flow path that comes into contact with the treated water and the portion of the screen that comes into contact with the treated water are ,iron The metal material is substantially free of nickel, chromium, manganese, aluminum, lead, or copper.

[0007] The ultrapure water production system of the present invention includes the above-described ion exchange device. [Effects of the Invention]

[0008] As described above, according to the present invention, it is possible to provide an ion exchange apparatus and an ultrapure water production apparatus in which the elution of metal components is minimized. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of an ultrapure water production apparatus according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of an ion exchange apparatus according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Fig. 1 is a schematic diagram showing the configuration of an ultrapure water production system according to one embodiment of the present invention, and Fig. 2 is a schematic cross-sectional view of an ion exchange device that constitutes the ultrapure water production system. Note that the configuration of the ultrapure water production system shown in the figure is merely an example and does not limit the present invention.

[0012] The ultrapure water production system 20 has a primary pure water tank 21, a pump 22, a heat exchanger 23, an ultraviolet oxidation device 24, an ion exchange device 1, a membrane degassing device 25, and an ultrafiltration (UF) membrane device 26. These components constitute a secondary pure water system (subsystem) that sequentially processes primary pure water produced in a primary pure water system (not shown) to produce ultrapure water, and supplies the ultrapure water to a point of use 27.

[0013] The water to be treated (primary pure water) stored in the primary pure water tank 21 is pumped out by a pump 22 and supplied to a heat exchanger 23. After passing through the heat exchanger 23 and having its temperature adjusted, the water to be treated is supplied to an ultraviolet oxidation device 24 where it is irradiated with ultraviolet light, thereby decomposing the total organic carbon (TOC) in the water to be treated. The water to be treated is then subjected to ion exchange treatment in an ion exchange device 1 to remove ionic components such as metal ions, dissolved gases are removed in a membrane degassing device 25, and particulates are removed in a UF membrane device 26. A portion of the ultrapure water thus obtained is supplied to a point of use 27, and the remainder is returned to the primary pure water tank 21. Primary pure water is supplied to the primary pure water tank 21 from a primary pure water system (not shown) as needed.

[0014] The primary pure water tank 21, pump 22, heat exchanger 23, ultraviolet oxidation device 24, membrane degassing device 25, and UF membrane device 26 can be devices commonly used in subsystems of ultrapure water production systems. On the other hand, the ion exchange device 1 can also be a non-regenerative mixed-bed ion exchange device (cartridge polisher) filled with a mixed bed of cation exchange resin and anion exchange resin, which is commonly used in subsystems of ultrapure water production systems, and its configuration has the following features.

[0015] The ion exchange device 1 has a resin tower 10, which is a cylindrical container filled with mixed-bed ion exchange resin (a mixture of cation exchange resin and anion exchange resin) 2. The resin tower 10 has a tower body 11, an upper socket 12 attached to the top of the tower body 11, and a lower socket 13 attached to the bottom of the tower body 11. The upper socket 12 defines an inlet flow path 12a through which water to be treated from the ultraviolet oxidation device 24 flows, and the lower socket 13 defines an outlet flow path 13a through which water treated by the ion exchange resin 2 flows. An inlet (opening) 12b communicating with the inlet flow path 12a is formed on a flat, horizontal top surface 3 within the resin tower 10, and an outlet (opening) 13b communicating with the outlet flow path 13a is formed on a flat, horizontal bottom surface 4 within the resin tower 10.

[0016] The ion exchange apparatus 1 also has an upper collector screen 5 provided to cover the inlet 12b in the resin tower 10 (i.e., fitted over the inlet 12b), and a lower collector screen 6 provided to cover the outlet 13b (i.e., fitted over the outlet 13b). Each of the collector screens 5, 6 is a wedge wire screen formed in a cylindrical shape with one open end. The upper collector screen 5 is attached to the inlet 12b at its open upper end, and the lower collector screen 6 is attached to the outlet 13b at its open lower end. As a result, the collector screens 5, 6 allow the inflow of water to be treated from the inlet flow path 12a into the resin tower 10 and the outflow of treated water from the resin tower 10 to the outlet flow path 13a, while the lower collector screen 6 in particular has the function of preventing the outflow of ion exchange resin 2 from the resin tower 10 to the outlet flow path 13a. The slit width of the wedge wire screen is set depending on the particle size of the ion exchange resin used, but is not particularly limited as long as it does not generate a differential pressure when water passes through.

[0017] The material of the resin tower 10 is not particularly limited as long as it has strength commensurate with the filling amount of the ion exchange resin 2. For example, a composite material such as fiber reinforced plastic (FRP) can be used for the tower body 11, and a synthetic resin such as polyvinyl chloride (PVC) can be used for the sockets 12 and 13. In addition, in the case of a large resin tower 10 in which the filling amount of the ion exchange resin 2 exceeds 1000 L, the tower body 11, the upper socket 12, and the lower socket 13 may be formed integrally, taking into consideration the initial cost and maintainability, and a metal material with higher strength, such as stainless steel (SUS), can be used as the material.

[0018] However, it is known that metal components such as calcium and cobalt leach out of FRP, and calcium and zinc leach out of PVC. Furthermore, experimental results described below have confirmed that metal components such as iron and nickel leach out more from SUS than from fluororesins such as perfluoroalkoxy fluororesin (PFA). Therefore, in this embodiment, to suppress the leaching of such metal components, the inner surface of the resin tower 10, which comes into contact with the liquid, is lined with a nonmetallic material. Examples of this nonmetallic material include synthetic resins, specifically fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), and polypropylene (PP). The sockets 12 and 13 defining the inlet flow path 12a and the outlet flow path 13a may themselves be made of fluororesins such as PTFE or PP.

[0019] However, in the case of a particularly large resin tower 10, applying the above-mentioned lining to the entire inner surface thereof would be extremely costly. For example, in a resin tower 10 made of SUS with an inner diameter of 1000 mm and a height of 1000 mm, if the surface area is 7 m 2 Lining the entire inner surface of the resin tower 10 with a fluororesin would cost more than 5 million yen. On the other hand, even if metal components leach out from the inner surface of the resin tower 10, if the ion exchange resin 2 is filled below that point, the leachable metal components can be removed by the ion exchange resin 2. Therefore, it is not necessary to line the entire inner surface of the resin tower 10 that comes into contact with the liquid. In other words, it is not necessary to line the portion of the resin tower 10 that comes into contact with the liquid, where even if metal components leach out from there, the metal components may be treated by the ion exchange resin 2 in a subsequent stage. Conversely, it is preferable to line at least the portion of the resin tower 10 that comes into contact with the liquid, where even if metal components leach out from there, the metal components may not be treated by the ion exchange resin 2 in a subsequent stage, specifically, the bottom surface 4 and the inner surface of the outlet flow path 13b that comes into contact with the liquid, are lined.

[0020] According to this concept, the curved surface 8 connecting the bottom surface 4 and the side surface 7 inside the resin tower 10 does not necessarily need to be lined, but in order to more reliably suppress the elution of metal components, it is preferable that such curved surface 8 also be lined. On the other hand, if the bottom surface 4 is not a flat horizontal surface but is composed of a curved surface such as a conical surface or a hemispherical surface, and the outlet 13a is formed at the very bottom thereof, the bottom surface 4 does not need to be lined.

[0021] On the other hand, from the viewpoint of suppressing the elution of metal components, it is preferable to use a non-metallic material such as synthetic resin as the material for the collector screens 5 and 6. However, considering the need to ensure sufficient strength, it is preferable to use a metallic material that elutes as little as possible. Specifically, it is preferable to use a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper. Examples of such metallic materials include titanium. According to the above-mentioned concept, the material of the upper collector screen 5 of the two collector screens 5 and 6 may be selected based solely on strength, and may be made of, for example, stainless steel. Furthermore, the term "substantially free" here means that the upper collector screen 5 may contain impurities as long as their elution has little effect on the quality of the treated water.

[0022] Below, we will explain the results of tests conducted by the present inventors to verify the elution of metal components from the resin tower 10 and the collector screens 5 and 6. The inventors' verification has revealed that, when ultrapure water with a metal concentration at the ng / L level is required, it may have been sufficient to consider only the elution of metal components from the resin tower 10, but in order to meet the stricter requirements of recent years (i.e., the pg / L level), it is important to consider not only the elution from the resin tower 10 but also from other components, particularly the collector screens 5 and 6.

[0023] (Test 1) First, to confirm the elution of metal components from a metal container, the inventors measured the concentration of metal components in the sample water at the container outlet when the sample water was passed through the container. Specifically, the sample water was passed through a SUS (SUS316) container filled with non-regenerative ion exchange resin, and then passed through a monolithic ion exchanger installed at the container outlet. The metal components in the sample water that flowed out of the container were captured by the ion exchanger, and then eluted into an eluent, and the amount of each metal in the eluent was measured. The container had an inner diameter of 1200 mm and a height of 1000 mm. Ultrapure water was passed through the container at a flow rate of 50 L / (L-resin·h) as the sample water. 100 mL of nitric acid, prepared by diluting Tama Chemicals Co., Ltd.'s high-concentration nitric acid (trade name: TAMAPURE AA-100) to 1 N or more, was used as the eluent. The amount of metal was measured using an inductively coupled plasma mass spectrometer (ICP-MS), and the metal concentration in the sample water flowing out of the container was calculated by dividing the measured amount of metal by the concentration factor of the eluent.

[0024] For comparison, the amount of metal elution from a non-metallic (PFA) container was also measured. The PFA container had an inner diameter of 26 mm and a height of 1000 mm, and the test was conducted under the same procedures and conditions as in the test described above, except that the sample water was passed through under the same flow conditions as in the metallic container. The concentrations of various metals in the sample water that flowed out of the container were calculated.

[0025] Table 1 shows the measurement results for metallic and non-metallic containers.

[0026] [Table 1]

[0027] From the measurement results shown in Table 1, it was confirmed that for all of the metals measured except for chromium, the amount of metal components eluted from a metal (SUS316) container was greater than that from a non-metal (PFA) container. For this reason, when using a resin tower made of metal, such as SUS, it is considered preferable to line the inner surface with a non-metallic material, such as synthetic resin.

[0028] (Test 2) Next, to confirm the elution of metal components from the metal collector screen, the inventors compared the amount of elution of metal components between a resin tower with and without a metal collector screen. Specifically, a resin tower similar to that shown in Figure 1 was used, except that it was not filled with ion exchange resin and the liquid-contacting parts were not lined. Tests were conducted using the same procedures as in Test 1 above, with and without SUS (SUS304) collector screens installed at the inlet and outlet, and the concentrations of various metals in the sample water were calculated. The resin tower used consisted of an FRP tower body with an inner diameter of 400 mm and a height of 1000 mm and a PVC socket. Ultrapure water was passed through the resin tower at a flow rate of 10 L / min as the sample water. Other conditions were the same as in Test 1 above.

[0029] Table 2 shows the measurement results with and without the collector screen installed.

[0030] [Table 2]

[0031] It was confirmed that the installation of a metal (SUS304) collector screen significantly increased the amount of iron elution. As mentioned above, the collector screen is a wedge wire screen formed into a cylindrical shape, and its structure makes it difficult to apply a lining made of a non-metallic material. Taking this into consideration, the measurement results shown in Table 2 indicate that the collector screen should be made of a non-metallic material, or, from the standpoint of strength, a metallic material that is substantially free of the metallic elements contained in SUS (specifically, iron, nickel, chromium, manganese, aluminum, lead, or copper).

[0032] (Test 3) Next, to confirm how the amount of eluted metal components changes depending on the metal material used for the collector screen, the inventors compared the amount of eluted metal components when two types of collector screens made of different materials were installed in a resin tower. Specifically, a resin tower similar to that shown in Figure 1 (except that the liquid-contacting parts were not lined; therefore, it was filled with a non-regenerative ion-exchange resin) was installed with a SUS (SUS304) collector screen and a titanium collector screen at the inlet and outlet, respectively. Tests were conducted using the same procedures as in Test 1 described above, and the concentrations of various metals in the sample water discharged from the container were calculated. The resin tower consisted of an FRP tower body with an inner diameter of 400 mm and a height of 1000 mm, and a PTFE socket. Pure water was passed through the resin tower at a flow rate of 10 L / min as the sample water. Other conditions were the same as in Test 1 described above.

[0033] Table 3 shows the measurement results when a SUS collector screen was installed and when a titanium collector screen was installed.

[0034] [Table 3]

[0035] The measurement results shown in Table 3 confirm that the amount of iron elution is significantly reduced when a titanium collector screen is installed compared to when a SUS collector screen is installed, confirming that titanium is preferable as the metal material for the collector screen. Note that the amount of iron elution is reduced when a titanium collector screen is installed compared to when no collector screen is installed in Test 2, which indicates that using a socket made of fluororesin is also effective in suppressing the elution of metal components.

[0036] Based on the above test results, in this embodiment, as described above, at least the bottom surface 4 and the inner surface of the outlet flow path 13b of the resin tower 10 are lined with a non-metallic material. Additionally, at least the lower collector screen 6 is made of a non-metallic material or a metallic material, preferably titanium, that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper. This prevents elution of metal components from portions of the liquid-contacting portion of the ion exchange device 1 that are unlikely to be treated by ion exchange resins in a subsequent stage. While a non-metallic material such as synthetic resin is preferred as the lining material for the resin tower 10, a metallic material may also be used as long as it minimizes the amount of eluted metal components. For example, a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper may also be used. Furthermore, the lower collector screen 6 does not necessarily have to be made of the above-mentioned material itself; only the surface that comes into contact with the treated water (liquid-contacting portion) may be made of the above-mentioned material, that is, it may be made of a non-metallic material or a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

[0037] Although not shown, a pipe connected to the outlet flow path 13a is attached to the bottom of the resin tower 10. If the pipe is made of a metal such as SUS, it is preferable that the inner surface of the pipe is also lined. As with the lining material of the resin tower 10, the material is preferably a non-metallic material, specifically, a synthetic resin such as a fluororesin, or a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

[0038] As mentioned above, the configuration of the ultrapure water production system 1 is not limited to the illustrated configuration, and therefore the installation location of the ion exchange device 1 is not limited to the illustrated location. For example, the membrane degassing device 25 may be omitted, thereby installing the ion exchange device 1 immediately upstream of the UF membrane device 26, which is the most downstream of the subsystem. Alternatively, the UF membrane device 26 may be omitted, thereby installing the ion exchange device 1 at the most downstream of the subsystem. Furthermore, the above-described configuration of the ion exchange device 1 is not limited to that of an ion exchange device installed in a subsystem as in this embodiment, but may also be applied to an ion exchange device constituting a primary pure water system. Furthermore, the type of ion exchange resin packed in the ion exchange device 1 is not limited to the mixed bed type of cation exchange resin and anion exchange resin described above. It may be a double-bed type of cation exchange resin and anion exchange resin, or a single-bed type of cation exchange resin or anion exchange resin. Furthermore, instead of or in addition to the ion exchange resin, a chelating resin may be packed. For example, the ion exchange device 1 may be packed with a single bed of chelating resin, or may be packed with a multiple bed or mixed bed of at least one of a cation exchange resin and an anion exchange resin and a chelating resin. [Explanation of symbols]

[0039] 1. Ion exchange device 2. Ion exchange resin 3 Top surface 4 Bottom 5 Upper Collector Screen 6 Lower Collector Screen 7 Side 8 Curved Surfaces 10 Resin tower (container) 11 Container body 12 Upper Socket 12a Inlet channel 12b Inlet 13 Lower Socket 13a Outlet channel 13b Outlet (opening) 20 Ultrapure water production equipment 21 Primary pure water tank 22 Pump 23 Heat exchanger 24 UV oxidation equipment 25 Membrane degassing device 26 Ultrafiltration membrane device 27 Use Points

Claims

1. a container filled with an ion exchange resin; an outlet flow path that penetrates a lower part of the container and communicates with an opening formed on a bottom surface of the container, and through which treated water treated with the ion exchange resin flows; a screen provided at the opening to prevent the ion exchange resin from flowing out of the container to the outlet channel; An ion exchange device wherein the portion of the outlet flow path that comes into contact with the treated water and the portion of the screen that comes into contact with the treated water are each made of a metal material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

2. 2. The ion exchange apparatus of claim 1, wherein the bottom surface of the container includes a horizontal surface in which the opening is formed, and the horizontal surface is made of a non-metallic material or a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

3. 3. The ion exchange apparatus according to claim 2, wherein the curved surface connecting the bottom and side surfaces of the container is made of a non-metallic material or a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

4. 4. The ion exchange device according to claim 2, wherein the non-metallic material is a fluororesin or polypropylene.

5. a pipe attached to a lower portion of the container and connected to the outlet flow path, through which the treated water from the outlet flow path flows; 5. The ion exchange apparatus according to claim 1, wherein the inner surface of the pipe is made of a non-metallic material or a metallic material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

6. An ion exchange apparatus as described in claim 5, wherein the non-metallic material is a fluororesin or polypropylene.

7. 7. The ion exchange apparatus according to claim 1, wherein the metal material substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper is titanium.

8. The ion exchange apparatus according to claim 1 , wherein the screen is formed in a cylindrical shape with one end open, and the one end is attached to the opening.

9. An ultrapure water production system comprising the ion exchange device according to any one of claims 1 to 8.

10. A container used in an ion exchange device and filled with ion exchange resin, an outlet flow path through which treated water treated with the ion exchange resin flows is connected to an opening formed in the bottom surface of the container, the outlet flow path passing through the bottom of the container, and a screen is provided to prevent the ion exchange resin from flowing out of the container to the outlet flow path; A container in which the portion of the outlet flow path that comes into contact with the treated water and the portion of the screen that comes into contact with the treated water are each made of a metal material that is substantially free of iron, nickel, chromium, manganese, aluminum, lead, or copper.

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