JP5391965B2 - Ion exchanger - Google Patents

Description

  The present invention relates to an ion exchange apparatus for performing ion exchange treatment by passing water through an ion exchange resin filled in a container, and in particular, a non-regenerative mixed bed ion exchange apparatus of a subsystem of an ultrapure water production apparatus. It is related with the ion exchange apparatus suitable for using as.

  An ultrapure water production device that produces ultrapure water from raw water such as city water, groundwater, and industrial water basically consists of a pretreatment device, a primary pure water production device, and a subsystem (secondary pure water production device). Is done. Among these, the pretreatment device is composed of agglomeration, levitation, and filtration devices. The primary pure water production apparatus includes two reverse osmosis membrane separation devices and a mixed bed ion exchange device, or an ion exchange resin device and a reverse osmosis membrane separation device. The subsystem (secondary pure water production apparatus) includes a low-pressure ultraviolet oxidizer, a mixed bed ion exchanger, an ultrafiltration (UF) membrane separator, and the like.

  Ultrapure water used in the manufacturing process of electronic devices such as semiconductors is required to have a very low concentration of metal components as impurities. In order to meet these requirements, as ion exchange devices, liquid contact members such as containers are made of synthetic resin or stainless steel, or are made of fluororesin-coated members. Is known.

i) Using an FRP (fiber reinforced plastic) container (Japanese Patent Publication No. 3-64195, Japanese Utility Model Publication No. 5-9113, Japanese Patent Laid-Open No. 6-86976, etc.)
An ion exchange resin apparatus in which an FRP container is filled with an ion exchange resin is widely used as a mass-produced product. Usually, the inner shell which is a wetted part is manufactured by blow molding a polymer material, and the outer shell is manufactured by FRP and reinforced.

  In paragraph 0024 of JP-A-6-86976, the wetted part is made of polyethylene or polypropylene and the outside thereof is reinforced with FRP.

ii) Using stainless steel members In Japanese Patent Laid-Open No. 2006-263718 and Japanese Patent Laid-Open No. 2007-7651, the case body and the upper lid are made of stainless steel. In JP-A-9-117677, a flat screen of SUS316 is used as a partition wall in an ion exchange column.

iii) A material such as a fluorine-based resin that does not elute components (Japanese Patent Laid-Open No. 8-231207, etc.)
Fluororesin has high chemical stability. In JP-A-8-231207, hydrogen ions are removed by a mixed bed type ion exchange resin column containing polytetrafluoroethylene (PTFE).

  However, these conventional techniques i) to iii) have the following disadvantages.

  In the case of i), since the container is manufactured by hardening the inner shell and the outer shell with an adhesive, there is a high risk that the liquid contact part (inner shell) will be contaminated during the manufacturing.

  In the case of ii) above, metal components are eluted from stainless steel.

  When using a fluororesin having high chemical stability as in iii) above, it is very difficult to process the fluororesin.

  In general, since a fluorine-based resin is expensive, it is not economical to produce a container or the like by injection molding, shaving or the like alone. Therefore, it is desirable that the container is made of high strength stainless steel, and the wetted surface is coated or lined with a fluororesin.

  There are various methods for coating or lining the fluororesin, but the sheet lining that requires an adhesive and the loose lining method that has no adhesion to the base material are equipment for obtaining high-purity ultrapure water. It is inappropriate as a processing method. Therefore, for the production of the container of the ion exchange device, coating or lining by electrostatic powder coating method or fluid immersion method is preferable.

  In the electrostatic powder coating method, a fine powder of fluororesin is sprayed onto a pre-charged base material with a spray gun, so that it is difficult to obtain a uniform film thickness when the apparatus structure is complicated. In addition, it is difficult to coat (or line) a fine uneven shape such as a screw thread while leaving the uneven shape by an electrostatic powder coating method.

  Even in the fluid dipping method, it is difficult to coat (or line) the entire liquid contact surface of the container while leaving the entire container surface coated (or lining) and leaving a fine uneven shape such as a screw thread.

  It is also conceivable that the metal member is first coated (or lined) with a fluorine-based resin, and then a container is manufactured using the metal member. However, compared with the melting point of the fluororesin (250 to 330 ° C.), the ultimate temperature in the vicinity of the welded portion during stainless steel welding is very high, so that the welding operation cannot be performed after coating (or lining). Further, when threading is performed after coating (or lining), stress is applied to the fluororesin film, leading to peeling of the film. Therefore, the apparatus manufacturing procedure is also greatly restricted.

  By the way, as a non-regenerative ion exchange apparatus of the subsystem, a container having an upper lid, an ion exchange resin filled in the container, and a water supported by the ion exchange resin were taken out by the upper lid. A type having a water collecting pipe and a strainer attached to the lower end of the water collecting pipe (for example, JP 2001-86976 A, JP 2001-104952 A, etc.) is widely used. This non-regenerative ion exchange apparatus is removed from the subsystem every one to two years, and replacement work of the ion exchange resin is performed. When replacing the ion exchange resin of the non-regenerative ion exchange apparatus, the water collecting pipe and the strainer are also removed and washed or replaced with a new one. Therefore, it is necessary to attach the water collecting pipe to the container top cover not by welding or by screwing in consideration of the coating (or lining) processing.

  In addition, when the sealing property of the attachment part to the upper cover of this water collection pipe | tube is inadequate, raw | natural water will leak in a short circuit to the inside of a water collection pipe | tube (treated water side), and treated water quality will fall.

  The ion exchange device disclosed in Japanese Patent Laid-Open No. 2001-104952 is used for a soft water device or a pure water production device (paragraph 0002 of the same publication) and cannot be applied to an ultrapure water subsystem having a very low impurity concentration. In addition, since an FRP tank such as the above publication has a relatively large dimensional error in manufacturing, it is necessary to adjust the axial direction of the water collecting pipe of the distributor using an O-ring and an adapter (paragraph 0006 of the publication).

  Further, in this Japanese Patent Application Laid-Open No. 2001-104952, a “spring that is elastically deformable in the axial direction (Claim 6)” is used for the adapter, and “the surface of the spring is made of resin (Claim 7)”. When such elastically deforming members are present in the container, they become sources of fine particles and the like, and high purity ultrapure water cannot be obtained.

Japanese Patent Publication 3-64195 Reality 5-9113 JP-A-6-86976 JP 2006-263718 A JP2007-7651 JP-A-9-117677 JP-A-8-231207 JP 2001-104952 A

  In the present invention, the liquid contact surface of the container and the container upper lid is made of a synthetic resin to prevent elution of metal components from the liquid contact part of the container, and the water collecting pipe can be easily detached and the raw water leaks into the water collecting pipe. An object of the present invention is to provide an ion exchange apparatus that is prevented.

The ion exchange apparatus of the present invention is an ion exchange apparatus in which an ion exchange resin is accommodated in a container having a wetted surface made of a synthetic resin, and the container is attached to the container body having an open top and the container body. A water collecting pipe provided with a raw water inlet and a water collecting pipe connecting portion provided on the upper cover, and having a strainer at the lower end thereof, the upper end of the water collecting pipe being connected to the water collecting pipe connecting portion. In the connected ion exchange apparatus, a cylindrical connector is connected to the upper end of the water collecting pipe, the connector is fitted to the water collecting pipe connecting portion, and a contact surface between the connector and the water collecting pipe connecting portion is It is sealed by two or more O-ring, the container body, top cover, the raw water inlet and water collecting pipe connecting portion is made of wetted surface is coated with a fluorine resin coating metal, wherein the water collecting tube, strainer and The connector is made of synthetic resin and the connector And the water collecting pipe connection portion of the tubular is inserted into the inner hole of, characterized in that said O-ring is held in an inner circumferential surface of the connector, the O-ring on the outer circumferential surface of the water collecting pipe connecting portion is in contact It is what.

  In the ion exchange apparatus of the present invention, the water collecting pipe is attached to the container upper lid with two or more O-rings and connectors. Since the connector is adapted to fit into the water collecting pipe connecting portion via the O-ring, the water collecting pipe can be easily detached and attached. In addition, since the fitting position of the connector to the water collecting pipe connecting portion can be finely adjusted, the vertical position of the strainer at the lower end of the water collecting pipe can be adjusted. Thereby, it can prevent that a strainer is pressed too strongly with respect to a container bottom face, and can also prevent that an excessive stress arises in the fluororesin coating | cover of this container bottom face.

  In the present invention, the liquid contact surfaces such as the container main body and the upper lid are made of synthetic resin, so that elution of metal components from the metal material constituting the container main body and the upper lid is prevented.

  In the present invention, when the connection between the container and the container top lid and the connection between the raw water pipe and the treated water pipe of the container top cover are clamped by a ferrule structure, the structure of the apparatus can be simplified and local stress is applied during tightening. Is prevented from occurring in a synthetic resin film such as a fluororesin.

It is sectional drawing of the container of the ion exchange apparatus which concerns on embodiment. It is an enlarged view of the top part of the container of FIG. It is typical sectional drawing which shows a test apparatus.

  The embodiment will be described below with reference to FIG. 1 and FIG. FIG. 1 is a longitudinal sectional view of a container of an ion exchange apparatus according to an embodiment, and FIG. 2 is an enlarged sectional view of a water collecting pipe connecting portion of the container.

  The container 1 is closed at the bottom and has a container body 2 that is open only on the top surface, an upper lid 3 mounted on the upper portion of the container body 2, a raw water inlet 4 provided on the upper lid 3, and a water collecting pipe connecting portion. 5, an ion exchange resin inlet 6, a water collecting pipe 8 whose upper end is connected to the water collecting pipe connecting portion 5 via a connector 7, a water collection strainer 9 attached to the lower end of the water collecting pipe 8, and the like. I have.

  In this embodiment, the container body 2 has a substantially cylindrical shape with the cylinder axis direction being the vertical direction, and a leg seat 2a is provided on the bottom surface of the bottom. A flange portion 2 b is provided on the outer periphery of the upper end edge of the container body 2. An O-ring groove (not shown) is recessed in the upper surface of the flange portion 2b, and an O-ring (not shown) is installed in the O-ring groove. The O-ring groove circulates around the container body 2.

  The container body 2 is made of metal (stainless steel in this embodiment), and the entire inner surface, the upper surface of the flange portion 2b, and the entire groove surface of the O-ring groove are covered with a fluororesin coating.

  The upper lid 3 has a disk shape, and its peripheral edge portion is overlapped with the flange portion 2 b and is connected to the flange portion 2 b by a clamp 10. The upper lid 3 is made of metal (stainless steel in this embodiment), and the entire lower surface thereof is covered with a fluororesin coating.

  The raw water inlet 4 has a cylindrical shape that penetrates the upper lid 3 and is fixed to the upper lid 3 by welding. A flange portion for connecting a raw water pipe (not shown) to the upper lid 3 by a ferrule (not shown). 4a is provided. A distributor 11 made of synthetic resin (polypropylene in this embodiment) for spraying raw water into the container body 2 is attached to the lower part of the raw water inlet 4 by ultrasonic welding or the like. The raw water inlet 4 is made of metal (stainless steel in this embodiment), and its liquid contact surface (the entire inner peripheral surface and the outer peripheral surface below the upper lid 3) and the upper surface of the flange portion 4a are coated with a fluororesin film. Covered with.

  The cylindrical ion exchange resin inlet 6 is made of metal (stainless steel in this embodiment) which is fixed to the peripheral edge of the opening 12 provided in the upper lid 3 by welding and rises upward. A flange portion 6a is provided. The entire inner peripheral surface of the inlet 6 and the upper surface of the flange portion 6a are covered with a fluororesin coating.

  A cap 6b is placed on the upper end of the insertion port 6, and is fixed to the flange portion 6a by a ferrule (not shown). By removing the ferrule, the cap 6 b can be removed from the insertion port 6.

  Next, the connection structure of the water collection pipe connection part 5 and the water collection pipe 8 to it will be described with reference to FIG.

  The water collecting pipe connecting portion 5 has a cylindrical shape penetrating the upper lid 3, and a flange portion 5 a for connecting a treated water extraction pipe (not shown) by a ferrule is provided at the upper end thereof. The water collecting pipe connecting portion 5 is inserted into an opening 13 provided in the upper lid 3 and fixed to the upper lid 3 by welding (reference numeral 14 indicates a weld metal of this welding).

  The lower part of the water collecting pipe connecting part 5 is thicker than the upper part, and the inner diameter of the lower part is smaller than the upper part by the thickness. The outer diameter of the water collecting pipe connecting portion 5 is the same from the upper end to the lower end except for the flange portion 5a. The water collecting pipe connecting portion 5 is made of metal (stainless steel in this embodiment), and the entire inner peripheral surface and the upper surface of the flange portion 5a are covered with the fluororesin coating 15. The fluororesin coating 15 is continuous from the flange portion 5 a to the inner surface of the water collection pipe connection portion 5.

  The connector 7 has a cylindrical shape into which the water collecting pipe connecting portion 5 and the water collecting pipe 8 are respectively inserted into the inner holes. A convex portion 7 a is provided on the inner peripheral surface of the substantially intermediate portion in the vertical direction of the connector 7 so as to go around the inner peripheral surface. On the inner peripheral surface of the upper portion of the connector 7, two O-ring mounting grooves (not shown) are provided at intervals in the vertical direction, and an O-ring 16 is mounted in each groove. The O-ring 16 is in watertight contact with the outer peripheral surface of the water collecting pipe connecting portion 5. Note that the number of O-rings 16 may be three or more.

  The water collecting pipe 8 and the connector 7 are made of a fluororesin (in this embodiment, PVDF), and the water collecting pipe 8 is inserted into the connector 7 until it preferably comes into contact with the convex portion 7a, and is fixed by ultrasonic welding or the like. .

  The strainer 9 is made of a synthetic resin such as polypropylene, and is fixed to the lower end of the water collecting pipe 8 by ultrasonic welding or the like.

  After fixing the connector 7 and the strainer 9 to the water collecting pipe 8, the water collecting pipe connecting portion 5 is fitted into the inner hole of the connector 7, whereby the water collecting pipe 8 is connected to the water collecting pipe connecting portion 5.

  It is preferable that the water collection pipe 8, the connector 7, the raw water distributor 11 and the water collection strainer 9 are made of a high-purity synthetic resin with little impurity elution. As described above, in this embodiment, the water collection pipe 8 and the connector 7 are made of PVDF. The raw water distributor 11 and the water collection strainer 9 are made of PP (polypropylene).

  The thickness of the fluororesin coating formed on the liquid contact part of the container main body 2 and the upper lid 3 is preferably about 100 to 800 μm, particularly about 200 to 500 μm, especially about 300 μm.

As a method for forming the fluororesin coating, an electrostatic powder coating method or a fluid immersion method is suitable. In the electrostatic powder coating method, a pre-heated adherend (such as a container body or an upper lid) is sprayed, and a fluororesin powder is sprayed with an electrostatic coating machine, and the powder is melted to form a film. In the fluidized immersion method, a fluidized bed is formed by flowing fluororesin powder with air or nitrogen gas, and a preheated adherend (such as a container body or top lid) is immersed in the fluidized bed to form a coating. To do. As the fluororesin, ETFE (tetrafluoroethylene (C ₂ F ₄ ) and ethylene (C ₂ H ₄ ) copolymer), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) and the like are suitable.

  The O-ring is preferably made of a high-purity rubber with little impurity elution, and a fluorine rubber O-ring is particularly suitable. Examples of fluororubbers used in the O-ring include Paiton (registered trademark of DuPont), Kalrez (registered trademark of DuPont), Afras (registered trademark of Asahi Glass Co., Ltd.), and the like.

  In the ion exchange apparatus configured as described above, the connector 7 is attached to the upper end of the water collecting pipe 8, and the water collecting pipe connecting portion 5 is fitted in the connector 7, and the inner peripheral surface of the connector 7 and the water collecting pipe A space between the outer peripheral surface of the connecting portion 5 is sealed by two or more O-rings 16. For this reason, it is easy to connect the water collecting pipe 8 and the water collecting pipe connecting portion 5, and the sealing property between the two is also good, and the raw water is prevented from leaking into the treated water.

  Further, in the connection structure of the water collecting pipe connecting portion 5 and the connector 7, the connector 7 can move up and down with respect to the water collecting pipe connecting portion 5. Therefore, the height of the water collection pipe 8 can be finely adjusted, and the water collection strainer 9 can be prevented from being strongly pressed against the bottom surface of the container body 2. Therefore, excessive stress is prevented from being generated in the fluororesin coating on the bottom inner surface of the container body 2.

  In this embodiment, the liquid contact surfaces of the container main body 2, the upper lid 3, the raw water inlet 4, the water collection pipe connection portion 5, and the inlet 6 are covered with a fluororesin film, and the distributor 11, connector 7, The water pipe 8 and the strainer 9 are made of a synthetic resin, so that metal elution is prevented.

  Therefore, according to this ion exchange apparatus, it is possible to obtain ion exchange treated water having a remarkably low metal concentration.

  Next, an experimental example in which leakage of metal ions from the raw water side into the water collection pipe 8 in the above ion exchange device is described.

<Experimental example 1>
In the ion exchange apparatus as shown in FIGS. 1 and 2 except that only one O-ring 16 is attached, the coating on the wetted surface of the stainless steel container body 2 and the upper lid 3 is an ETFE coating having a thickness of 300 μm. The water collecting pipe 8 and the connector 7 are made of PVDF, and the distributor 11 and the strainer 9 are made of PP. As shown in FIG. 3, the lower end of the water collecting pipe 8 is closed with a PVDF closing plate 20 instead of the strainer 9, the water collecting pipe 8 is filled with ultrapure water, and a cap 19 is attached to the upper end of the water collecting pipe 8. . While extracting air from the container 1, a NaCl aqueous solution having a Na ion concentration of 10 g / L in the raw water tank 21 was injected into the container 1 from the raw water inlet 4 through the pump 22 and the pipe 23 until the container 1 became full. After the inside of the container 1 was filled with NaCl aqueous solution, the inside of the container 1 was pressurized with the pump 22 until the indicated value of the pressure gauge 24 reached 0.7 MPa. Reference numeral 25 in FIG. 3 indicates a ferrule in which the tip of the pipe 23 is connected to the flange portion 4 a of the raw water inlet 4.

  The pump 22 was stopped with this pressure maintained, and the system was allowed to stand for 1 hour, and the Na concentration in the water collecting pipe after 1 hour was measured. The results are shown in Table 1.

<Experimental example 2>
The test was conducted in the same manner as in Experimental Example 1 except that the number of O-rings was two as shown in FIG. The results are shown in Table 1.

<Experimental example 3>
The test was performed in the same manner as in Experimental Example 1 except that the number of O-rings was three. The results are shown in Table 1.

  As shown in Table 1, when there are two or more O-rings, the Na concentration in the water collecting pipe is 10 μg / L or less (parts per million or less with respect to the raw water), and sufficient sealing performance can be obtained. Admitted.

DESCRIPTION OF SYMBOLS 1 Container 2 Container main body 3 Top cover 4 Raw water inflow port 5 Water collecting pipe connection part 6 Ion exchange resin inlet 7 Connector 8 Water collecting pipe 9 Strainer 11 Distributor 15 Fluoropolymer coating 16 O-ring

Claims (1)

An ion exchange device containing an ion exchange resin in a container having a wetted surface made of synthetic resin,
The container includes a container body whose upper part is open, an upper lid attached to the container body, and a raw water inlet and a water collecting pipe connecting portion provided in the upper lid,
In an ion exchange apparatus in which a water collecting pipe having a strainer at a lower end is disposed in the container, and an upper end of the water collecting pipe is connected to the water collecting pipe connecting portion,
A cylindrical connector is connected to the upper end of the water collecting pipe, the connector is fitted to the water collecting pipe connecting portion, and the contact surface between the connector and the water collecting pipe connecting portion is sealed with two or more O-rings. and,
The container body, the upper lid, the raw water inlet and the water collecting pipe connection part are made of metal whose liquid contact surface is coated with a fluororesin coating,
The water collecting pipe, strainer and connector are made of synthetic resin, and the tubular water collecting pipe connecting portion is inserted into the inner hole of the connector,
An ion exchange apparatus , wherein the O-ring is held on an inner peripheral surface of the connector, and the O-ring is in contact with an outer peripheral surface of a water collecting pipe connecting portion .

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