JPH01245817A - Hot superpure water generating apparatus - Google Patents

Abstract

PURPOSE:To perform pasteurization in the region of high temperature to obtain hot superpure water by providing, besides an ion-exchange device, a filter including a ceramic membrane therein at the last stage of a hot superpure water generating apparatus to prevent the elution of organic matters or particulates. CONSTITUTION:Raw water fed from an inlet pipe 1 passes through an ion- exchange device 3, whereby the ion components in the raw water are removed nearly completely by means of ion-exchange fibers and also the specific resistance of the raw water is raised approximately to 18.2MOMEGA.cm. Thereafter, the raw water, at the time of passing through heating devices 5A, 5B connected to the downstream side of the device 3, is heated to 60-95 deg.C to form hot pure water, during which pasteurization thereof is performed. Further, the water is passed through cylindrical ceramic tubes of a filter 7 disposed at the rear of the heating devices 5A, 5B, during which particulates, TOC, metal ions, etc., are removed from the water to turn it to hot superpure water, which is supplied to a use point or a recycle pipe.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to pure water with a specific resistance of 18 MΩ·cm or more used in the electronic industry, medical use, etc., whose temperature is 60 to 95
The present invention relates to an apparatus for producing so-called hot ultrapure water heated to about °C.

[Conventional technology] Semiconductor manufacturing technology has made remarkable progress in the electronics industry, with ultra-fine patterns and higher integration, and we are now entering the era of ultra-super LSIs, represented by dynamic memories of 4 megabits or more. It is known that the ultrapure water required for cleaning silicon wafers is preferably high-temperature ultrapure water, that is, thermal ultrapure water, in order to increase the cleaning effect.

As a thermal ultrapure water production device used for such applications,
The applicant previously proposed in Japanese Patent Application No. 62-90943 an ion exchange device using ion exchange fibers, a water pump, a reverse osmosis membrane device using a reverse osmosis membrane, and a heating device in this order. A device connected in series was proposed.

[Problems to be Solved by the Invention] However, since the above-mentioned conventional device uses a reverse osmosis membrane module, an ultrafiltration membrane module, etc. made of an organic material as a filtration material, it is not heat resistant in a high temperature range exceeding 60'C. There was a drawback that 1q of hot ultrapure water in this temperature range could not be obtained. Moreover, in the above-mentioned high-temperature range, organic matter elution from the membrane and module members becomes noticeable, and there are also problems such as generation of fine particles in the heating device and piping to the point of use.

This tendency is the same in various known filters in which a known organic flat membrane is installed just before the point of use.
In fact, it has been difficult to produce thermal ultrapure water in the above-mentioned high temperature range.

Furthermore, since the conventional apparatus described above cannot perform sterilization treatment by raising the temperature, it requires chemical sterilization that requires periodic shutdown of the apparatus, and there is also the problem that the operating time of the apparatus is short.

The present invention solves these problems and provides a hot ultrapure water production device that does not elute organic substances or fine particles and can produce high purity hot ultrapure water without waste without chemical sterilization. The purpose is to

[Means for Solving the Problems] The structure of the present invention for solving the above problems is as follows. In other words, (a) an inlet pipe for raw water, (b) an ion exchange device containing ion exchange fibers for receiving the raw water and converting it into pure water, and (c) heating the pure water to produce thermally pure water. (d) a filtration device containing a ceramic membrane for further increasing the degree of purification of the thermally pure water to produce thermally ultrapure water; and (e) interconnecting each of the devices. (f) a supply pipe for supplying the hot ultrapure water from the filtration device to the point of use; and (g) a connection pipe branched from the supply pipe and connected to the introduction pipe or the connection pipe. In addition, it is a thermal ultrapure water production device equipped with a recycling pipe for recycling the thermal ultrapure water.

Further, the configuration of the present invention for effectively utilizing 1 q of heated ultrapure water without wasting it is as follows.

(b) an inlet pipe for raw water; (b) an ion exchange device containing ion exchange fibers for receiving the raw water and converting it into pure water; and (c) heating the pure water to make thermally pure water. (d) a filtration device containing a ceramic membrane for further increasing the degree of purification of the thermally purified water to produce thermally ultrapure water; and (e) interconnecting each of the devices. a connecting pipe; (f) a heat exchanger interposed in at least one of the connecting pipes; (g) a supply pipe for supplying the hot ultrapure water from the filtration device to the point of use; A recycle pipe for recycling the hot ultrapure water, which is branched from the supply pipe and connected to the heat exchanger.

Here, the raw water to be treated in the present invention, that is, the raw water supplied from the inlet pipe, may be commonly used tap water, industrial water, etc. By pretreatment with so-called primary pure water production equipment such as exchange resins and ultraviolet germicidal lamps, or so-called secondary pure water production equipment such as known ion exchange resins (Polylasha), ultraviolet germicidal lamps, and ultrafiltration membranes. , the quality of the treated water is such that the specific resistance is 16 MΩ・cm or more and the number of fine particles is 1.
000 cells/m1 or less, TOC below 1000 ppb, viable bacteria count 1000 cells/rrd! It is preferable that the degree of purification is as high as below. However, in applications that do not require high purity water, without adding the above-mentioned secondary treatment or secondary treatment,
It may also be one that has been simply subjected to a simple pretreatment such as filtration.

In addition, an ion exchange device introduces the above-mentioned raw water, removes the ionic components in the raw water, and reduces the specific resistance to 18°2MΩ・c.
This is a known water treatment device that uses ion exchange fibers or the like as an ion exchanger to make water pure by increasing the water concentration to about m or more. Further, a known ion exchange membrane may be used as the ion exchanger.

In addition, the heating device is connected to the rear part of the ion exchange device, which introduces the pure water obtained in the water treatment device and raises the temperature to about 60 to 95°C to make hot pure water. It is a heating device. The configuration of this heating device is not particularly limited, but
For example, a known electric heating device consisting of an aluminum cast-in type electric heater, a temperature sensing end, a controller, etc., a known double pipe type steam heating device using steam or a heating medium as a heat source on the heating side, etc. are preferable. In addition, when ultrapure water boils inside the heating device, more metal ions will be eluted from the metal surface of the heating device, so in order to avoid rapid heating, the transferred heat is dispersed and the heating temperature is gradually increased. It is preferable to use a type heating device. For example, electrolytic polishing, more preferably chromium M (Cr03),
It is preferable to perform oxidative passivation treatment using concentrated nitric acid (HNO3) or the like. The heating device is connected to the front of the filtration device in order to prevent the growth of bacteria in the filtration device, but the heating device may be connected to the rear of the filtration device in addition to the front of the filtration device.

Next, the filtration device is a ceramic membrane for the purpose of reducing TOC (total organic carbon), number of fine particles, number of viable bacteria, metal ions, etc., and removing silica in the hot pure water introduced from the heating device. Refers to a known water treatment device using This filtration device is a final treatment device that improves the treated water quality of the supplied raw water, and filters the hot pure water heated by the aforementioned heating device through a ceramic membrane to improve the water quality with a specific resistance of 18.2 MΩ.
・The number of fine particles with a diameter of cm or more and a diameter of 0.05 μm or more is 1/d
Hereinafter, by purifying the TOC to about 1 opppb or less, hot ultrapure water will be obtained.

Then, this hot pure water passes through the supply pipe to the next process, i.e.
Supplied to point of use.

In addition, a ceramic membrane is a porous support material made by sintering metal oxide fine particles, and on the surface layer of the porous support material, metal oxide fine particles having a smaller particle size than the metal oxide fine particles constituting the support material are added. The filter medium is composed of porous sintered rM and is described in detail in Japanese Patent Application No. 60-261437.

More preferably, both the porous support material and the porous sintered cline are composed of porous sintered bodies containing alumina and zirconia as main components.

In addition, the material of the wetted parts other than the filter medium of this filtration device is preferably austenitic stainless steel for corrosion resistance reasons.
More preferably, 5US316L is used, and the surface roughness is Rm
It is preferable to perform oxidative passivation treatment at axl of 0 μm or less.

In addition, the recycle pipe is used to recycle surplus hot ultrapure water into the raw water introduction pipe, connection pipe, or these pipes when 1 q of hot ultrapure water produced by the filtration device cannot be used at the point of use. Return it to an interposed heat exchanger etc.
This is a return pipe for regenerating raw water or as a heat source for recovering waste heat.

Among the materials of the wetted parts of the above-mentioned components of the apparatus of the present invention, the materials of the apparatus and piping located upstream from the heating apparatus are suitable for elution of metal ions into ultrapure water from these apparatuses,
For the purpose of preventing rust, fine particles, etc. from entering, for example, 5U8
Stainless steel such as 304, polyvinyl chloride resin,
Synthetic resins such as polypropylene resin and polyvinylidene fluoride resin are preferably used, more preferably 5US3
16 series materials are preferred. In addition, the material of piping after the heating device and the material of the wetted parts of the device that comes into contact with hot ultrapure water should be austenitic stainless steel, more preferably 5US31.
It is preferable to use 6L and set the surface roughness to RmaXl, 0 μm or less.

In addition, in the thermal ultrapure water production apparatus of this invention, the individual water flow resistances of the filter media, such as ion exchange fibers and ceramic membranes, are approximately 0.5 to 2.0 k (including the water flow resistance of all filter media). /7.
Since the pressure is as low as approximately G, the water supply pressure of the water supply pump built into the pretreatment device can be used without the need to newly install a water supply pump for pressurization.

[Function] By passing the raw water supplied from the introduction pipe through the ion exchange device, the ionic components in the raw water are almost completely removed, the specific resistance is raised to about 18.2 MΩ・Cm, and the , by passing through a heating device connected downstream of this ion exchanger, the temperature is raised to 60 to 9.
The temperature is raised to about 5°C and it becomes thermally pure water. Additionally, this heating process sterilizes the product.

Next, a filtration device installed at the return section of the heat exchanger tests the quality of the treated water until the final resistivity is 18.2MΩ・Cm and 0.05MΩ・Cm.
The number of particles with a diameter of μm or more is 1/d or less, and the TOC is 1op.
The water is raised to below PB and becomes hot ultrapure water.

In addition, hot ultrapure water that cannot be consumed at the point of use is returned from the recycling pipe to the upstream raw water introduction pipe, connecting pipe, heat exchanger, etc., and is reused.

[Example] FIG. 1 shows a 70-sheet showing an example of the apparatus according to the present invention, and a detailed description will be given below based on this figure.

1 is an introduction pipe for supplying raw water, and 2 is a diaphragm valve for adjusting the supply amount. 3 is an ion exchange fiber ("l0NEX" TlN100 type manufactured by Toshi Co., Ltd.) at a ratio of 1.2 to 9.
It is a filled ion exchange device and is housed in a 5US316L container with a diameter of 150 mm and a length of 400 mm. Reference numeral 4 denotes a double-tube heat exchanger, through which treated water treated by the ion exchange device 3 is passed through an inner tube. This double pipe heat exchanger 4 has an inner cylinder diameter of 15A and an outer cylinder diameter of 25A.
Made of 316L, the length of the inner cylinder is 10 m, and the inner surface roughness of the inner cylinder is treated to Rmax o, 1 μm.

5A and 5B are cylindrical electric heating devices whose outer periphery is covered with aluminum cast heaters, two of which are connected in series through a temperature detection end 6A for temperature control of this heating device, and furthermore, the connecting part A temperature sensing end 6B is connected to the temperature sensing end 6B. The length of the heating section of each heating device is 5m, and the material is 5US3.
16L, and the inner surface is electrolytically polished (surface roughness Rma
x 0.1 μm).

Further, 7 is a shell-and-tube type filtration device (details will be described later) having a built-in known cylindrical ceramic tube.

16 is a water quality meter that measures the final water quality of the hot ultrapure water, and 17 is a three-way automatic valve, the opening degree of which is adjusted according to the amount of hot ultrapure water consumed at the point of use. Among the three ports of the three-way automatic valve 17, the inlet port is connected to the conduit 18, and the outlet port is connected to the hot ultrapure water supply pipe 19 and the conduit 20. The conduit 20 is further connected to a conduit 14 and a double-pipe heat exchanger 4, and is connected from the conduit 15 to a known pure water production apparatus (not shown).

Note that 21.23 to 27 not mentioned above are conduits made of 5US316L whose inner surfaces are electropolished and connect the front and rear components, and 22.28 is the conduit 23.27.
This is a pressure sensing end embedded in the ion exchanger 3 and the filtration device 7 to transmit a secondary side pressure signal to the pressure controller 30 in order to determine the degree of clogging of the ion exchange device 3 and the filtration device 7.

Next, the structure of the filtering device 7 will be explained in more detail with reference to FIGS. 2 and 3.

FIG. 2 is a longitudinal cross-sectional view of the filtration device 7, and 71 is a cylindrical ceramic tube (east side) with an outer diameter of 1 om, an inner diameter of 6 mm, and a length of 600 mm, with sintered 'a layers formed on both the inner and outer layers. Ceramic membrane TAZ type manufactured by Co., Ltd.) with a diameter of 250 m.
Cylindrical container 7 made of 5US316L with a length of 900 mm
2 contains 90 filters (the filtration area of the outer layer is 1.7 m2). The shell side and the tube side are kept watertight from each other by fitting O-rings into both ends of the cylindrical ceramic tube 71. The material of this O-ring is silicone rubber, and eluted substances must be removed by extraction with hot water at 100° C. in advance. Further, 73 is a hot pure water introduction port, 74 is a hot pure water blowing port, and 75 is a hot pure water inlet where the hot pure water that has flowed in from the introduction lower 3 passes through the wall of the cylindrical ceramic tube 71. This is a hot ultrapure water intake for taking out purified water.

FIG. 3 is a longitudinal sectional view of the tube wall of the cylindrical ceramic tube 71, with the upper side of the figure being outside the tube and the lower side being inside the tube.

In the figure, 76 is a sintered body layer of metal oxide fine particles with an average particle size of 2 to 10 μm, and on top of the sintered body layer, the metal oxide fine particles 76 and an average particle size of 0.03 to 0.1 μm are formed.
A porous sintered layer 78 is formed with metal oxide fine particles 77 of 0 μm. A porous support material 79 is formed by the metal oxide fine particles 76 and the porous sintered layer 7B.

Furthermore, the surface layer portion of the porous support material 79 has an average particle size of 0.
A cline 80 made of a porous sintered layer of metal oxide with a thickness of 0.02 to 0.01 μm is formed. This cline 80 does not exist only on the surface of the porous support material 79;
It extends to the porous sintered layer 78. Since the porous sintered layer 78 and the filter layer 80 are intertwined and bonded together in this way, the 'fj1 layer 80 is stable and does not peel off even when hot pure water passes from the inside of the tube to the outside of the tube.

When the filter layer 80 exists only on one surface of the porous support material 79 as described above, fine particles in pure water, TOC1 metal ions, etc. may accumulate in the voids of the support material. Therefore, preferably m1ao is formed on both sides of the porous support material 79.

According to such a cylindrical ceramic tube 71, the fine particles and TO in the hot pure water are removed by the porous sintered layer 79 on the side in contact with the hot pure water.
It filters C1 metal ions, fine particles, dissolved substances, etc., but even if some defect occurs in the porous sintered layer 79 and foreign matter flows in, it has a dual separation function that allows it to be filtered by the filter layer 80. .

Next, the operation of the apparatus of the present invention constructed in this manner will be further explained with reference to FIG.

From the direction of the arrow on the left side of the figure, resistivity 17 MΩ・cm, number of fine particles 1000 particles/d or less, treated with a known pretreatment device,
Number of viable bacteria 1000 cells/d or less, water pressure 2°5-3.5kL'
CI? When raw water at a temperature of about 20 to 30°C is supplied to the ion exchange equipment 3 via the raw water introduction pipe 1 and the diaphragm valve 2 by a pump (not shown) of the pretreatment equipment, the ion exchange fibers are purified here. The action causes ion exchange of the raw water, and the specific resistance of the treated water improves to about 18.2 MΩ-cm.

This treated water is passed through the conduit 23 to the double-pipe heat exchanger 4, where the temperature is raised to about 30 to 60'C by excess hot pure water or surplus hot ultrapure water flowing in from the conduit 14. Preheated. The preheated treated water is passed through the conduit 23 to the two heating devices 5A and 5B. First, the first stage heating device 5A raises the temperature to a specified temperature of 50 to 80°C, and then 2
The final temperature of this example is 60~ in the heating device 5B of the third stage.
The temperature is raised to about 95°C. These specified temperatures are controlled by temperature sensing terminals 6A, 6B and temperature controller 29, respectively.

Next, the heated hot pure water passes through the conduit 26 to the filtration device @7.
Approximately 90% of the water flow is filtered by this device, but in the process, due to the action of the ceramic membrane,
The number of fine particles with a particle size of 0.05 μm or more in the treated water is 1/ml
Hereinafter, the number of viable bacteria is raised to less than TOolog) pb and less than 0.1 cells/d, and the final water quality as thermal ultrapure water in this thermal ultrapure water production apparatus is achieved.

On the other hand, the flow rate of hot pure water that does not pass through the ceramic membrane is set to approximately 10% by the diaphragm valve 10 and the flow meter 11 in order to ensure the filtration performance of the ceramic membrane. 13°14.15 and is returned to the pretreatment device.

In addition, if the entire amount of hot ultrapure water is not used at the point of use and surplus hot ultrapure water is generated, the valve opening degree of the three-way automatic valve 17 is adjusted according to instructions from the temperature controller 29, and the surplus hot ultrapure water is The water is returned to the double-pipe heat exchanger 4 through the conduit 20.14 and used as waste heat recovery water.

Moreover, the specified pressures at the pressure detection ends 9, 22, and 28 are 3, 5 kg/cri, G, and 2.5 kMcff1, respectively.
G, 0°5~2.0kC1/cff1. G, and the pressure controller 30 constantly monitors these pressures.

Here, each pressure detection end 9, 22, 28 and the three-way automatic valve 17 are interlocked, and the ion exchange fiber of the ion exchange device 3, the ceramic membrane of the filtration device 7, etc. are prevented from deteriorating the filtration performance due to clogging with foreign matter. If a problem occurs, such as a drop in the secondary side pressure of the ion exchange device 3, a rise in the temporary side pressure of the filtration device 7, or a drop in the pressure of flowing hot ultrapure water to the point of use, the pressure controller 30 immediately At the same time as issuing an alarm signal, the three-way automatic valve 17 is closed to stop water supply to the point of use.

For the apparatus of this embodiment having the grooves as described above, the processing conditions were as follows: water supply pressure: 3.5 kL/CIi, G, i! ! The secondary side pressure of 0.5 kCI/CIA, G, ceramic membrane permeation flow rate of 90%, and the set temperatures of heating devices 5A and 5B were set to 60°C and 95°C, respectively, and the treatment was performed with the pretreatment equipment. When the raw water was supplied at a rate of 12.1/min, the rate was 94.5
1 q of hot ultrapure water at ℃ was added at a flow rate of 11 rLZ.

In addition, the quality of the supplied hot pure water has a specific resistance of 18゜OMΩ.
-cmXO, the number of particles larger than 05 μm is 30 pieces/m! ,
Although the OC was 40 ppb, the quality of the hot ultrapure water that passed through the filtration device 7 had a specific resistance of 18°2MΩcmSo,
Number of particles larger than 0.05μm is 1/d, TOC is 1opp
It was b.

On the other hand, the 1.1/min hot pure water that did not pass through the ceramic membrane was returned to the pretreatment device via the blow tube 8 and the heat exchanger 4.

According to the device of this embodiment, there is no need to specifically provide a water pump in the device, so there is no mixing of fine particles into the hot ultrapure water due to rotation of the pump impeller, sliding of the bearing, etc.

In addition, since the heating devices 5A and 5B are divided into multiple stages and the heating range of pure water per stage of the heating device is set small, rapid heating is prevented, and elution of ionic components from the heating device is reduced. It has the unique effect of shortening the temperature rise time.

Next, FIG. 4 is a flow sheet showing another embodiment of the thermal ultrapure water production apparatus of the present invention.

The difference between this device and the hot ultrapure water production device shown in FIG. a three-way automatic valve 17 that opens and closes to allow the water to pass through to the filtration device 7; and a conduit 32 connecting this valve and the conduit 14.
This is because we have established the following. In this way, only the amount of hot ultrapure water required at the point of use passes through the ceramic membrane of the filtration device 7 and becomes hot ultrapure water, so there is no need to place unnecessary filtration burden on the ceramic membrane. The unique effect is that clean hot ultrapure water can be obtained because the performance of the system is stable, and there are fewer parts between the filtration device 7 and the point of use that can cause impurities to be mixed in.

[Effects of the Invention] In addition to the ion exchange device, the device of the present invention does not elute TOC between the heating device and the hot ultrapure water supply pipe, that is, in the final stage of the hot ultrapure water production device. In addition, the filtration device is equipped with a stable ceramic membrane that does not elute inorganic substances, improving specific resistance and reducing TOC. It can ultimately remove particles, dirt, foreign matter, etc. generated from pipes, etc.

In addition, since a heat-resistant ceramic membrane is used in the filtration device at the rear of the heating device, hot ultrapure water at a high temperature of 60 to 95°C, which was previously impossible, can be easily obtained, and sterilization is also possible. can be done effectively.

゛Furthermore, a recycling pipe for excess hot ultrapure water, a heat exchanger, etc. are installed, making it possible to recover waste heat and making use of hot ultrapure water without waste.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing an embodiment of the thermal ultrapure water production apparatus according to the present invention, FIG. 2 is a longitudinal cross-sectional view of the filtration device shown in FIG. 1, and FIG. 1 is a vertical cross-sectional view of a main part of a cylindrical ceramic tube. FIG. 4 is a flow sheet of a thermal ultrapure water production apparatus according to the present invention, which is different from the apparatus shown in FIG. 1: Raw water introduction pipe 2: Diaphragm valve 3: Ion exchange device 4: Double pipe heat exchanger 5A, 5B: Heating device 6A, 6B: Temperature sensing end 7: Filtration device 8 Niblow tube 10: Diaphragm valve 11: Flowmeter 12-15.18-21.23-27.32: Conduit 16: Water quality meter 17: Three-way automatic valve 9.22.28: Pressure detection end 29: Temperature controller 30: Pressure controller 31: Flow rate controller

Claims (2)

[Claims] (1) (B) An inlet pipe for raw water; (B) An ion exchange device containing ion exchange fibers for receiving the raw water and converting it into pure water; (C) Heat purifying the pure water by heating it. (d) A filtration device containing a ceramic membrane for further increasing the degree of purification of the thermally pure water and converting it into thermal ultrapure water; and (e) mutually interconnecting each of the devices. (f) a supply pipe for supplying the hot ultrapure water from the filtration device to the point of use; (g) branched from the supply pipe and connected to the introduction pipe or the connection pipe; A thermal ultrapure water production device equipped with a recycling pipe for recycling the thermal ultrapure water that has been produced. (2) (a) an inlet pipe for raw water; (b) an ion exchange device containing ion exchange fibers for receiving the raw water and converting it into pure water; and (c) heating the pure water to thermally purify it. (d) a filtration device containing a ceramic membrane for further increasing the degree of purification of the thermally pure water and converting it into thermal ultrapure water; and (e) interconnecting each of the devices. (f) a heat exchanger interposed in at least one of the connecting pipes; (g) a supply pipe for supplying the hot ultrapure water from the filtration device to the point of use; (H) A recycling pipe for recycling the hot ultrapure water, which is branched from the supply pipe and connected to the heat exchanger.