Subsystem for ultrapure water

Abstract

This invention provides a subsystem for ultrapure water equipped with an ion exchanger that offers excellent leak prevention characteristics at the bottom of the container. [Solution] The ultrapure water subsystem includes a heat exchanger 2, a degassing membrane device 4, UV oxidation devices 6A and 6B, an ion exchanger 10, and an MF device 12. The lower ports 6b of the UV oxidation devices 6A and 6B are connected to each other. The housing 22 of the ion exchanger 10 has a body portion 22a and a bottom portion 22c as a single unit, and a lower strainer 23 and an upper strainer 25 are arranged inside. The upper strainer 25 is supported by an inner case 24 along the inner circumferential surface of the housing 22. A top block 26 is provided on the upper side of the housing 22 and is connected to the housing 22 by a union nut 27.

Description

Technical Field

[0001] The present invention relates to a ultrapure water subsystem for producing ultrapure water.

Background Art

[0002] Ultrapure water used as water for semiconductor cleaning is produced by an ultrapure water production apparatus including a primary pure water production apparatus and a subsystem (secondary pure water production apparatus) (Patent Document 1).

[0003] In the subsystem, TOC is decomposed into organic acids and further into CO2 by 185 nm ultraviolet light emitted from a low-pressure ultraviolet lamp in an ultraviolet oxidation device (hereinafter sometimes referred to as a UV oxidation device), and the organic substances and CO2 generated by the decomposition are removed by a subsequent ion exchanger.

[0004] An ion exchanger in which an ion exchange resin is accommodated in a container is configured such that water to be treated is supplied into the container and brought into contact with the ion exchange resin, and anions and cations in the water to be treated are adsorbed (ion exchanged) onto the ion exchange resin to obtain pure water (for example, Patent Documents 2 and 3).

[0005] As an ion exchanger, one in which an ion exchange resin is filled in a cylindrical container having an inflow port at a lower part and an outflow port at an upper part is commercially available. A top end cap and a bottom end cap are respectively fixed to the upper end and the lower end of this container by a screwing method with respect to the container. In such an ion exchanger in which the upper and lower end caps are fixed to the container by the screwing method, there is a risk of water leakage from the thread surface between the container and the lower end cap.

[0006] In the ion exchanger (Patent Document 3) in which an ion exchange resin is accommodated in a cylinder-type container having a water collector arranged inside, the size of the ion exchanger increases because the water collector and a water collection pipe connected to the water collector are arranged inside the container.

Prior Art Literature

Patent Literature

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-64342 [Patent Document 2] Japanese Patent Application Publication No. 7-232165 [Patent Document 3] Japanese Patent Publication No. 2007-245006 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention aims to provide an ultrapure water subsystem equipped with an ion exchanger that has excellent leak prevention characteristics at the bottom of the container. In one embodiment, the present invention also aims to provide an ultrapure water subsystem equipped with a compact ion exchanger. [Means for solving the problem]

[0009] The present invention relates to an ultrapure water subsystem comprising a UV oxidation device and an ion exchanger containing an ion exchange resin in a container, wherein the container of the ion exchanger has a body and a bottom portion that are integrally connected, and the bottom portion has a pure water outlet, and a top block that has an inlet for the water to be treated and is attached to the top of the housing. The housing is characterized by having an upper strainer and a lower strainer positioned at the top and bottom of the housing, respectively, with an ion exchange resin contained between the strainers.

[0010] In one aspect of the present invention, an upward step is provided at the lower part of the inner circumferential surface of the housing, and the outer circumferential edge of the lower strainer is supported by the upward step.

[0011] In one aspect of the present invention, an inner case is provided along the inner circumferential surface of the housing, the lower part of the inner case is connected to the lower strainer, and the upper strainer is supported at the upper end of the inner case.

[0012] In one aspect of the present invention, the housing and the top block are connected by a union nut.

[0013] In one aspect of the present invention, the UV oxidation apparatus has ports at the top and bottom, two UV oxidation apparatuses are placed side by side, and the lower port of one first UV oxidation apparatus is directly connected to the lower port of the other second UV oxidation apparatus. Water flows in from the upper port of the first UV oxidation apparatus, passes through the first and second UV oxidation apparatuses in sequence, and flows out from the upper port of the second UV oxidation apparatus.

[0014] In one aspect of the present invention, a portion of the ultrapure water produced by the ultrapure water subsystem is configured to be returned to the upstream side of the UV oxidation apparatus via a sampling pipe, and a water quality sensor is installed in the sampling pipe. [Effects of the Invention]

[0015] The ion exchanger used in the ultrapure water subsystem of the present invention does not have an end cap at the bottom of the container, and therefore has excellent leakage prevention characteristics at the bottom of the container. Furthermore, since the ion exchanger used in the ultrapure water subsystem of the present invention does not have a water collector and water collection piping connected to the water collector inside the container, it can be made smaller. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram showing the configuration of an ultrapure water subsystem according to an embodiment. [Figure 2] This is a longitudinal cross-sectional view of an ion exchanger according to an embodiment. [Figure 3] This is a longitudinal cross-sectional view showing the engagement relationship between the inner case and the lower strainer. [Modes for carrying out the invention]

[0017] The ultrapure water subsystem and the ion exchanger used therein, according to the embodiment, will be described below with reference to Figures 1 to 3.

[0018] As shown in Fig. 1, in the ultrapure water subsystem according to this embodiment, primary pure water passes from a pipe 1 through a heat exchanger 2 and is cooled. Cold water is passed through the heat exchanger 2 via pipes 2A and 2B. The heat exchanger 2 is for temperature control of secondary pure water. Generally, the supply temperature of secondary pure water (room-temperature ultrapure water) is 23 to 25°C, and cold water is used as a cooling source for the heat exchanger 2 to control the temperature within this range. Furthermore, this heat exchanger 2 is disposed upstream of the ion exchanger 10, and prevents TOC components from eluting due to contact between high-temperature pure water and the ion exchange resin.

[0019] Pure water that has passed through the heat exchanger 2 is passed to a degassing membrane device 4 via a pipe 3. The degassing membrane device 4 is partitioned into a water chamber and a gas chamber by a degassing membrane 4m. The inside of the gas chamber is decompressed by a vacuum pump (not shown in the drawings), and gases such as carbon dioxide in the water flowing through the water chamber permeate through the degassing membrane 4m and are removed from the water.

[0020] Pure water that has passed through the degassing membrane device 4 is passed to a UV oxidation device (low-pressure UV oxidation device) 6 via a pipe 5. In the UV oxidation device 6, 185 nm ultraviolet rays emitted from a low-pressure ultraviolet lamp 6c decompose TOC into organic acids and further into CO2. In this embodiment, two UV oxidation devices, a first UV oxidation device 6A and a second UV oxidation device 6B, are installed in series.

[0021] Each of the UV oxidation devices 6 (6A, 6B) has the low-pressure ultraviolet lamp 6c disposed inside a vertically elongated casing, and ports (water inflow or outflow ports) 6a and 6b are provided at the upper portion and lower portion of the casing, respectively. In this embodiment, each of the ports 6a and 6b has a flange at the tip end. The lower ports 6b, 6b of the UV oxidation devices 6A and 6B are directly connected to each other by coupling the flanges to each other. A packing or an O-ring is interposed between the flanges. The pipe 5 is connected to the upper port 6a of the first UV oxidation device 6A.

[0022] The UV-treated water flowing out from the upper port 6a of the second UV oxidation apparatus 6B is passed through piping 7, pump 8, and piping 9 to the ion exchanger 10. In this embodiment, two ion exchangers 10 are installed in parallel. Organic matter and CO2 generated in the UV oxidation apparatus 6 are removed in this ion exchanger 10. The water flowing out from the ion exchanger 10 is passed through piping 11 to the MF apparatus 12 to remove particulate matter and particles flowing out from the ion exchange resin, resulting in ultrapure water. A UF ​​apparatus may be installed instead of the MF apparatus.

[0023] Ultrapure water from the MF device 12 is supplied to the point of use via piping 13. A portion of the ultrapure water is returned to piping 1 via piping 14, which branches off from piping 13. The ultrapure water flows from piping 13 to piping 1 through piping 14 due to the discharge and suction pressure of pump 8. A resistivity meter 15 is installed in piping 14 as a water quality sensor. Other water quality sensors may also be installed.

[0024] The ion exchanger 10 will now be described with reference to Figures 2 and 3. As shown in Figure 2, the ion exchanger 10 includes a housing 22 that constitutes the main body of the container, and an ion exchange resin (not shown) is housed within the housing 22.

[0025] The housing 22 has a cylindrical body portion 22a, a flange portion 22b that widens in diameter from the outer circumference of the upper end of the body portion 22a, a bottom surface portion 22c connected to the lower part of the body portion 22a, a nozzle portion 22d projecting downward from the bottom surface portion 22c, a male screw 2e engraved on the outer surface of the nozzle portion 2f, an outlet 22f that penetrates the bottom surface portion 22c and the nozzle portion 22d, and an upward-facing stepped portion 22g provided on the lower inner surface of the body portion 22a. The lower strainer 23 is positioned so as to be supported by the stepped portion 22g.

[0026] A cylindrical inner case 24 is positioned along the inner circumferential surface of the body 22a. The lower end of the inner case 24 is connected to the lower strainer 23. The outer circumferential surface of the inner case 24 is in contact with the inner circumferential surface of the body 22a. The upper end of the inner case 24 is located slightly below the upper end of the body 22a.

[0027] The upper strainer 25 is positioned so as to be supported by the upper end surface of the inner case 24. The upper strainer 25 is disc-shaped and has numerous water passage holes 25a. The upper strainer 25 is installed horizontally, and its outer edge is supported by the upper end of the inner case 24.

[0028] The housing 22 is open upwards, and a lid-like part 2 is provided to cover this opening.

[0029] The lower outer circumferential surface of the top block 26 is provided with a flange portion 26a that overlaps with the flange portion 22b of the housing 22, and male threads 26b are engraved on the outer circumferential surface of the flange portion 26a.

[0030] The lower end of the top block 26 has an annular portion 26g that protrudes below the flange portion 22b, and this annular portion 26g fits inside the upper end of the housing 22.

[0031] A nozzle portion 26c is provided projecting upward from the center of the top block 26, and male threads 26d are engraved on the outer surface of the nozzle portion 26c. An inlet 26e for the water to be treated is provided in the center of the top block 26 so as to penetrate the nozzle portion 26c.

[0032] The top block 26 is fixed to the housing 22 by a union nut 27. The union nut 27 has a lower inward-facing flange 27a that engages with the flange 22b of the housing from below, and an upper inner-circumferential female thread 27b that screws onto the male thread 26b of the top block 26.

[0033] In this embodiment, the lower strainer 23 is a combination of the first strainer 30 and the second strainer 40, as shown in Figure 3.

[0034] The first strainer 30 has a disc-shaped portion 31, a number of water passage holes 32 provided in the disc-shaped portion 31, an upward-facing annular wall portion 33 rising upward from the outer peripheral edge of the disc-shaped portion 31, a pin hole 34 provided in the upward-facing annular wall portion 33, and a downward-facing annular wall portion 35 protruding downward from the outer peripheral edge of the disc-shaped portion 31.

[0035] The second strainer 40 is disc-shaped and has numerous water passage holes 41. The arrangement pattern of the water passage holes 32 and 41 is the same. The second strainer 40 is superimposed on the first strainer 30 such that the water passage holes 32 and 41 overlap each other, and is fitted inside the downward-facing annular wall portion 35.

[0036] The inner circumferential surface of the downward-facing annular wall portion 35 and the outer circumferential surface of the second strainer 40 have a tapered shape that decreases in diameter towards the bottom. The diameter of the upper surface of the second strainer 40 is larger than the diameter of the lower end of the downward-facing annular wall portion 35, thereby ensuring that the second strainer 40 is held in place by the first strainer 30 without falling off.

[0037] As shown in Figure 3, the lower end of the inner case 24 has a small-diameter portion 24a with a smaller outer diameter. This small-diameter portion 24a fits inside the upward-facing annular wall portion 33 of the first strainer 30. Multiple pin holes 24b are provided in the small-diameter portion 24a at positions that overlap with the pin holes 34 of the first strainer 30. The pin holes 24b and 34 are provided at equal intervals in the circumferential direction. The lower strainer 23 and the inner case 24 are connected by inserting pins (not shown) into the pin holes 24b and 34.

[0038] Although not shown in the diagram, the upper strainer 25 also consists of two strainers stacked on top of each other, with the lower strainer held in place by the downward-facing annular wall of the upper strainer. In the case of the upper strainer 25, there is no upward-facing annular wall.

[0039] After inserting the connecting body of the lower strainer 23 and the inner case 24 into the housing 22, ion exchange resin is filled into the inner case 24, and then the upper strainer 25 and top block 26 are placed and the union nut 27 is tightened to form the ion exchanger 10. Although not shown in the figures, O-rings are interposed between the flange portions 22b and 26a, between the upper strainer 25 and the lower end surface of the annular portion 26g of the top block 26, and between the lower strainer 23 and the stepped portion 22g.

[0040] A water supply pipe (not shown) is connected to nozzle 26c, and a pure water outlet pipe (not shown) is connected to nozzle 22d. The water to be treated flows into the ion exchanger 10 from inlet 26e, comes into contact with the ion exchange resin, undergoes ion exchange treatment, and pure water flows out from outlet 22f.

[0041] In this embodiment, the housing 22, strainers 23 and 25, inner case 24, top block 26, and union nut 27 are all made of synthetic resin.

[0042] In this ion exchanger 10, the bottom portion 22c of the housing 22 is integrally connected with the body portion 22a, providing excellent water leakage prevention characteristics from the bottom of the housing 22. Furthermore, since there is no bottom end cap, the assembly of the ion exchanger 10 is also easy.

[0043] This ion exchanger 10 can be made smaller because it does not have a water collector and water collection piping connected to the water collector located inside the container.

[0044] In this embodiment, since the inner case 24 and the lower strainer 23 are connected, the lower strainer 23 can be moved in and out of the housing 22 together with the inner case 24, making it easy to assemble and maintain the ion exchanger 10.

[0045] This ion exchanger 10 and the UV oxidation apparatus 6A, 6B assembly are suitable for installation in a narrow space (for example, within a frame of about 50 x 50 x 200 cm).

[0046] The above embodiment is just one example of the present invention, and the present invention may be in any other form. For example, a convex portion projecting in the centripetal direction may be provided on the inner circumferential surface of the upper end of the inner case 24 to increase the support area of ​​the upper strainer 25 by the inner case 24. Alternatively, one or more pairs of flat surfaces may be provided on the outer circumferential surface of the housing 22 so that a tool can be engaged with these flat surfaces when tightening the union nut 27 to hold down (prevent rotation of) the housing 22. [Explanation of Symbols]

[0047] 2 Heat exchanger 4. Degassing membrane device 6 UV oxidation equipment 10 Ion exchanger 12 MF device 22 Housing 22a Body 22c Bottom part 22f Outlet 22g stepped section 23 Lower Strainer 24 Inner Cases 25 Upper Strainer 26 Top Block 26e Inlet 27 Union nut 30. First Strainer 33 Upward-facing annular wall section 35 Downward-facing annular wall section 40. Second Strainer

Claims

1. In an ultrapure water subsystem having a UV oxidation device and an ion exchanger containing an ion exchange resin in a container, The container of the ion exchanger is The housing consists of a body and a bottom section that are integrated as a single unit, with a pure water outlet provided in the bottom section. A top block is attached to the top of the housing, and has an inlet for the water to be treated. It is equipped with, An ultrapure water subsystem characterized in that an upper strainer and a lower strainer are arranged at the top and bottom of the housing, respectively, and an ion exchange resin is housed between the strainers.

2. The ultrapure water subsystem according to claim 1, wherein an upward-facing step is provided at the lower part of the inner circumferential surface of the housing, and the outer circumferential edge of the lower strainer is supported by the upward-facing step.

3. An inner case is provided along the inner circumferential surface of the housing, The lower part of the inner case is connected to the lower strainer, The ultrapure water subsystem according to claim 2, wherein the upper strainer is supported at the upper end of the inner case.

4. The ultrapure water subsystem according to any one of claims 1 to 3, wherein the housing and the top block are connected by a union nut.

5. The UV oxidation apparatus has ports at the top and bottom, respectively. Two UV oxidation devices are placed side by side, with the lower port of one first UV oxidation device directly connected to the lower port of the other second UV oxidation device. An ultrapure water subsystem according to any one of claims 1 to 4, wherein water flowing in from the upper port of the first UV oxidizer passes sequentially through the first and second UV oxidizers and flows out from the upper port of the second UV oxidizer.

6. The system is configured to return a portion of the ultrapure water produced in the ultrapure water subsystem to the upstream side of the UV oxidation apparatus via a sampling pipe. An ultrapure water subsystem according to any one of claims 1 to 5, wherein a water quality sensor is installed in the sampling piping.

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