JP7016331B2 - Ultrapure water production method using an ultrafiltration membrane module and an ultrafiltration membrane module - Google Patents

Description

The present invention relates to an ultrapure water production method using an ultrafiltration membrane module and an ultrafiltration membrane module.

Conventionally, ultrapure water used for manufacturing electronic / electrical parts such as semiconductors and display elements is manufactured by using an ultrapure water manufacturing system. In the ultrapure water production system, for example, a pretreatment unit that removes suspended substances in raw water to obtain pretreatment water, and a reverse osmosis membrane device or a reverse osmosis membrane device that uses all organic carbon (TOC) components and ionic components in the pretreatment water. It consists of a primary pure water production unit that produces primary pure water by removing it using an ion exchange device, and a secondary pure water production unit that produces ultrapure water by removing trace amounts of impurities in the primary pure water. Has been done. As raw water, city water, well water, groundwater, industrial water, etc. are used. Further, as the raw water, used ultrapure water recovered at the place where the ultrapure water is used (use point: POU) (hereinafter referred to as "reclaimed water") may be used.

In the secondary pure water production unit, the primary pure water is highly processed by an ultraviolet oxidizing device, an ion exchange pure water device, an ultrafiltration membrane (UF) device, and the like to generate ultrapure water. The ultrafiltration membrane device is arranged near the last stage of the secondary pure water production section, and removes fine particles generated from an ion exchange resin or the like.

This ultrafiltration membrane device is configured to include a plurality of ultrafiltration membrane modules containing a bundle of hollow yarn-shaped ultrafiltration membranes inside a tubular case, depending on the amount of water collected and the like. The ultrafiltration membrane module is generally an external pressure type that supplies raw water to the outside of the hollow fiber membrane, and an ultrafiltration membrane module that collects filtered water from both ends and collects water from both ends, or one of them. There is a one-ended ultrafiltration membrane module that supplies water to be treated from one end and collects filtered water from the other end (see, for example, Patent Documents 1 and 2).

In the ultrafiltration membrane module, the components of the chemicals used in the manufacture of the ultrafiltration membrane, or the components such as the adhesive and potting agent used when incorporating the ultrafiltration membrane into the module, elute during use. May contaminate the permeated water. Therefore, the ultrafiltration membrane module is usually washed before it is applied to the production of ultrapure water, and the ultrafiltration membrane module for the purpose of easily cleaning the above-mentioned contaminants is manufactured. A method has been proposed (see, for example, Patent Document 3). Further, as a potting agent for adhesively sealing the ultrafiltration membrane, a material with less elution of organic substances has been proposed (see, for example, Patent Document 4).

Japanese Unexamined Patent Publication No. 7-96152 International Publication 2012/043679 Japanese Unexamined Patent Publication No. 2001-129366 JP-A-2017-136548

By the way, in recent years, with the miniaturization of semiconductor integrated circuits, the objects to be cleaned of ultrapure water (substances removed by cleaning) have been diversified, and the number of objects to be cleaned that are difficult to clean has increased. Therefore, in the cleaning of semiconductors, warm ultrapure water obtained by heating ultrapure water is also used in order to improve the detergency. In addition, the demand for ultrapure water quality is becoming more and more stringent due to the demand for high-cleaning of washed products. Under these circumstances, the present inventors have left an extremely small amount of ionic components (chloride ion ( ^Cl- ), etc.) in the ultrapure water supplied from the secondary pure water production section of the ultrapure water production apparatus. I found out that. In particular, in the warm ultrapure water that has passed through the secondary pure water production section, it was found that this trace ion component hinders the improvement of the water quality of the ultrapure water. Then, this trace ion component is the elution of the component of the drug used in the production of the ultrafiltration membrane and the component such as the adhesive and the potting agent used when incorporating the ultrafiltration membrane into the module. I found out that. However, ultrafiltration membrane modules in which no eluent or almost no eluate is generated near the production conditions of warm ultrapure water (for example, 80 ° C.) have not yet been put on the market. Therefore, there has been a demand for the development of an ultrafiltration membrane module that reduces the generation of eluted substances.

The present invention has been made based on the above findings, and is an ultrafiltration membrane module capable of significantly reducing the concentration of trace ion components in ultrapure water, particularly warm ultrapure water, and an ultrafiltration membrane module using the same. It is an object of the present invention to provide a method for producing pure water.

The ultrafiltration membrane module of the present invention is an ultrafiltration membrane module including a plurality of hollow fiber membranes made of an ultrafiltration membrane, a tubular case accommodating the plurality of hollow fiber membranes, and an ultrafiltration membrane module. The tubular case is provided on the outer peripheral surface thereof with a first nozzle and a second nozzle disposed apart from each other in the axial direction of the tubular case, and at both ends of the tubular case. Axial direction of the tubular case so that the opening ends of the plurality of hollow fiber membranes of the third nozzle and the fourth nozzle and the plurality of hollow fiber membranes face each of both ends of the tubular case. At each position between one end of the tubular case and the first nozzle and between the other end of the tubular case and the second nozzle. The first nozzle is a water-treated water introduction pipe into which the water to be treated is introduced, and the second nozzle does not permeate the hollow fiber membrane. It is a concentrated water outflow pipe that discharges concentrated water, the third nozzle is a permeation water outflow pipe that discharges permeated water that has permeated the hollow fiber membrane, and the fourth nozzle permeates the hollow fiber membrane. It is characterized by being an ultrafiltration pipe that allows the discharged water to flow out.

In the ultrafiltration membrane module of the present invention, it is preferable that the permeated water outflow pipe is provided closer to the concentrated water outflow pipe than the treated water introduction pipe.

In the ultrafiltration membrane module of the present invention, the fixing portion is preferably made of an epoxy resin.

In the ultrafiltration membrane module of the present invention, the value of the ratio of the outflow amount from the permeated water outflow pipe to the outflow amount from the outflow water outflow pipe (outflow amount from the permeated water outflow pipe / outflow from the outflow water outflow pipe). The amount) is preferably 90/10 or more and 99/1 or less.

The method for producing ultrapure water of the present invention is an ultrafiltration membrane module comprising a plurality of hollow fiber membranes made of an ultrafiltration membrane, a tubular case accommodating the plurality of hollow fiber membranes, and the ultrafiltration membrane module. The tubular case has a first nozzle and a second nozzle arranged apart from each other in the axial direction of the tubular case on the outer peripheral surface thereof, and a second nozzle arranged at both ends of the tubular case. The nozzle 3 and the fourth nozzle and the plurality of hollow fiber membranes are placed in the axial direction of the tubular case so that the open ends of the plurality of hollow fiber membranes face each of both ends of the tubular case. While fixing along the tubular case, the tubular case is located between one end of the tubular case and the first nozzle and between the other end of the tubular case and the second nozzle. In the ultrafiltration module provided with a pair of fixing portions for sealing, water to be treated is introduced into the ultrafiltration membrane module from the first nozzle, and the hollow fiber membrane is introduced from the second nozzle. The concentrated water that does not permeate is discharged, the permeated water that has permeated the hollow fiber membrane is discharged from the third nozzle of the tubular case, and the discharged water that has permeated the hollow fiber membrane is discharged from the fourth nozzle. It is characterized in that the permeated water is obtained as ultrapure water.

In the method for producing ultrapure water of the present invention, it is preferable that the chloride ion (Cl ⁻ ) concentration in the water to be treated is 0.01 μg / L or more and 2 μg / L or less (as Cl).

In the method for producing ultrapure water of the present invention, it is preferable that the chloride ion (Cl ⁻ ) concentration in the water to be treated is 1 ng / L or less (as Cl).

In the method for producing ultrapure water of the present invention, it is preferable that the chloride ion (Cl ⁻ ) concentration in the permeated water of the ultrafiltration membrane module is 5 ng / L or less (as Cl).

In the present specification, the reference numeral of "to" represents a numerical range including the numerical values on both sides thereof.

According to the ultrafiltration membrane module of the present invention, when the water to be treated is treated to produce ultrapure water, particularly warm ultrapure water, the concentration of trace ion components can be significantly reduced.
According to the method for producing ultrapure water of the present invention, it is possible to obtain ultrapure water having a significantly reduced trace ion component, particularly ultrapure water suitable for warm ultrapure water.

It is sectional drawing which shows typically the ultrafiltration membrane module which concerns on 1st Embodiment. It is a block diagram schematically showing the ultrapure water production system which concerns on 1st Embodiment. It is a block diagram schematically showing the modification of the ultrapure water production system which concerns on 1st Embodiment. It is a figure which shows the schematic structure of the ultrafiltration membrane apparatus in the ultrapure water production system which concerns on 2nd Embodiment. It is a figure which shows the schematic structure of the other ultrafiltration membrane apparatus in the ultrapure water production system which concerns on 2nd Embodiment. It is a graph which shows the time-dependent change of the chloride ion concentration in the permeation water of Example 1 and the comparative example. It is a graph which shows the relationship between the permeation water discharge flow rate ratio and the chloride ion concentration in permeation water in Example 2. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
In the ultrafiltration membrane module 10 of the present embodiment shown in FIG. 1, a plurality of hollow fiber membranes 1, a tubular case 2 accommodating the hollow fiber membrane 1, and both ends of the hollow fiber membrane 1 are tubular cases. It is provided with a pair of fixing portions 3a and 3b to be fixed inside. The ultrafiltration membrane module 10 has pipe connection caps 60a and 60b having nozzles 6a and 6b at both ends of the tubular case 2, respectively. Grooves are formed in the contact portions 61a and 61b of the piping connection cap with the end of the tubular case 2, respectively, and the piping connection cap includes an О ring (not shown) arranged in the groove and a part of the piping connection cap. Is attached to the tubular case 2 by a nut (not shown) that covers and fixes to the end of the tubular case 2.

The tubular case 2 is provided with nozzles 2a and 2b on the outer peripheral surface thereof. The nozzles 2a and 2b are arranged on the outer peripheral surface of the tubular case 2 so as to be separated from each other in the axial direction of the tubular case 2. Although the nozzles 6a and 6b may be arranged in opposite positions in FIG. 1, it is preferable that the nozzles 6b are provided closer to the nozzles 2b than the nozzles 2a as shown in FIG.

The hollow fiber membrane 1 is, for example, a yarn bundle in which a plurality of hollow fiber membranes are bundled together. Alternatively, the hollow fiber membrane 1 may be divided into small bundles in which a part of a plurality of hollow fiber membranes housed in the tubular case 2 is put together, and the small bundles are put together. The yarn bundle or small bundle of the hollow fiber membrane 1 may be entirely wrapped in a polypropylene net, a non-woven fabric, or the like. By collecting the hollow fiber membranes in a thread bundle and arranging them in the tubular case 2, the hollow fiber membrane 1 is filled between the hollow fiber membrane 1 and the inner peripheral surface of the tubular case 2 in the tubular case 2. A portion (a portion having a low film filling density) that is not formed is formed, whereby the resistance of water flowing outside the hollow fiber membrane 1 is reduced, and higher module water permeability can be realized.

An ultrafiltration membrane is used as the hollow fiber membrane 1. The fractional molecular weight of the ultrafiltration membrane is preferably 4000 to 6000, the effective membrane area is preferably 10 m ² to 35 m ² , and the design operating differential pressure is preferably 0.1 MPa to 0.4 MPa. As for the fine particle removing performance of the ultrafiltration membrane, it is preferable that the removal rate of fine particles having a particle diameter of 20 nm or more is 65% or more. The design operating differential pressure is in the range of the operating differential pressure (difference between the pressure of the permeated water and the pressure of the supplied water) in which the blocking rate of impurities in the ultrafiltration membrane is 90% from the maximum value to the maximum value. The design operating differential pressure may be a value published by the manufacturer as the standard operating pressure of the ultrafiltration membrane.

The material of the hollow fiber membrane may be appropriately selected depending on the intended use, and can be selected from, for example, polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate and polyacrylonitrile.

The inner diameter of the hollow fiber membrane is preferably 0.50 to 1.0 mm, and particularly preferably 0.70 mm to 0.85 mm.

The tubular case 2 is made of a cylindrical member having openings at both ends. The tubular case 2 has nozzles 2a and 2b provided near the interfaces Fa and Fb of the fixing portions 3a and 3b. The interface of the fixed portion means the surface of the fixed portion on the side where the hollow fiber membrane 1 is housed in the tubular case 2. The material of the tubular case 2 can be appropriately selected from among metals and plastics according to the intended use. From the viewpoint of ease of processing and weight reduction, the tubular case 2 is preferably made of plastics. Examples of the material of the tubular case 2 include polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinylidene fluoride, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), vinyl chloride resin and the like. The nozzles provided near the interfaces Fa and Fb do not necessarily have to be one, and a plurality of nozzles may be provided near the interfaces Fa and Fb, respectively.

The size of the tubular case 2 can be appropriately selected depending on the amount of water to be treated. As an example, the outer diameter is preferably 140 to 200 mm and the length is preferably 700 to 1400 mm, and the outer diameter is 160. It is particularly preferable that the diameter is about 180 mm and the length is 800 to 1200 mm. When the tubular case 2 having a size in this range is used, a high module water permeability and the highest module water permeability can be realized. Further, with the above size, the ultrafiltration membrane module 10 can be made to a weight that can be held by one person, so that there is an advantage that the handling property is remarkably good. The "outer diameter" of the tubular case 2 means the outer diameter of the cylinder in the central filtration region of the ultrafiltration membrane module 10. The "length" of the tubular case 2 means the distance between both end faces of the hollow fiber membrane.

The fixing portions 3a and 3b seal the outer surfaces of the hollow fiber membranes 1 and the gaps between the outer surfaces and the inner surface of the tubular case 2 at both ends of the hollow fiber membrane 1 in the tubular case 2. The fixing portions 3a and 3b fix the hollow fiber membrane 1 along the axial direction (longitudinal direction) of the tubular case 2, so that the open ends of the hollow portions of the hollow fiber membrane 1 are both ends of the tubular case 2. Each is exposed on the part side. During water treatment, permeated water will flow out from this open end.

As the material of the fixing portions 3a and 3b, a thermosetting resin such as an epoxy resin or a urethane resin is used. Epoxy resin is preferable as the material for the fixing portions 3a and 3b because the elution is small. Epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and trishydroxymethane type. Epoxy resin, tetraphenol ethane type epoxy resin, tetraglycidyl diaminodiphenylmethane type epoxy resin, aminophenol type epoxy resin, aniline type epoxy resin, benzylamine type epoxy resin, xylenediamine type epoxy resin, etc. Be done.

The materials of the fixing portions 3a and 3b are selected according to the material of the hollow fiber membrane 1, the adhesion to the hollow fiber membrane 1, the strength of the hollow fiber membrane 1, and the like. As the material of the fixing portions 3a and 3b, those having a small amount of elution components are preferable. Specifically, as an example of this material, the hollow fiber membrane 1 is used for a hollow fiber membrane module having an effective membrane area of about 34 m ² and a module outer diameter of 160 to 180 mm and a length of 800 to 1200 mm. The material preferably has a chloride ion elution amount of 10 ng / L or less, preferably 6 ng / L or less, when it comes into contact with warm pure water at about 70 to 80 ° C. By using a material in which the elution of the organic component is suppressed as the material of the fixing portions 3a and 3b, the elution amount of the organic component can be suppressed.

The ultrafiltration membrane module 10 of the present embodiment may have a pair of straightening vanes extending from the positions of the interfaces Fa and Fb of the fixing portions 3a and 3b toward the center of the module 10. If a rectifying cylinder that surrounds both ends of the fixing portions 3a and 3b and the hollow fiber membrane 1 is provided, damage to the hollow fiber membrane in the vicinity of the interfaces Fa and Fb can be effectively prevented.

Piping is connected to the nozzles 2a and 2b and the nozzles 6a and 6b of the ultrafiltration membrane module 10 of the present embodiment, and the water to be treated is supplied, the permeated water is sampled, and the concentrated water is discharged. In the ultrafiltration membrane module 10, for example, the nozzle 2a is a water introduction pipe to be treated (first nozzle), and the nozzle 2b is a concentrated water outflow pipe (second nozzle). Further, the nozzle 6a is used as a drainage water outflow pipe (fourth nozzle), and the nozzle 6b is used as a permeation water outflow pipe (third nozzle). For example, the nozzle 2b (concentrated water outflow pipe) is connected to a concentrated water pipe 101 having a variable opening valve V1 interposed therebetween, and the nozzle 6a (drainage water outflow pipe) is interposed with a valve V2 having a variable opening degree. The drainage pipe 102 is connected. Further, a water pipe 103 to be treated is connected to the nozzle 2a (water introduction pipe to be treated), and a permeation water pipe 104 is connected to the nozzle 6b (permeate water outflow pipe).

The water to be treated is introduced into the ultrafiltration membrane module 10 from the nozzle 2a and is filtered in the process of flowing from the outside to the inside of the hollow fiber membrane. It flows out from the nozzle 6b. Further, a part of the permeated water flows out from the nozzle 6a, which is a drainage water outflow pipe, as drainage water.

As the water to be treated, water from which ionic components, non-ionic components, dissolved gas and fine particles have been removed from raw water by ion exchange treatment, degassing treatment, ultraviolet oxidation treatment, ultrafiltration, microfiltration and the like can be used. Examples of such water to be treated include primary pure water or pure water having a TOC (total organic carbon) concentration of 5 μg C / L or less and a specific resistivity of 17 MΩ · cm or more. The amount of ionic components in the water to be treated is, for example, a chloride ion (Cl ⁻ ) concentration of 0.01 μg / L to 2 μg / L (as Cl, the same applies hereinafter), and 0.01 μg / L to 0.1 μg. / L is preferable.

The temperature of the water to be treated is preferably 10 ° C. or higher and 90 ° C. or lower, and more preferably 20 ° C. or higher and 80 ° C. or lower. When hot water having a high temperature is used as the water to be treated, the amount of eluate from the fixed portions 3a and 3b tends to increase. Therefore, by setting the temperature within the above range, it is easy to obtain a great effect in suppressing the eluate.

According to the ultrafiltration membrane module 10 of the above embodiment, permeated water having a significantly reduced ionic component can be obtained from the nozzle 6b. This is considered to be due to the following reasons. In the ultrafiltration membrane module of the water collection method at both ends, the permeated water generated in the ultrafiltration membrane module passes through the nozzles 6a and 6b through contact with the fixing portions 3a and 3b provided near both ends of the tubular case. leak. At the time of contact between the permeated water and the fixed portions 3a and 3b, it is presumed that the elution component from the material of the fixed portions 3a and 3b is mixed with the permeated water to cause contamination. Specifically, this elution component is an ionic component such as an organic component or a chloride ion (Cl ⁻ ). The higher the water temperature, the more the elution component tends to increase.

On the other hand, in the ultrafiltration membrane module 10 of the present embodiment, a part of the permeated water generated in the ultrafiltration membrane module flows out from the nozzle 6b and is used as ultrapure water. At this time, the permeated water comes into contact with the fixing portion 3b provided near one end of the tubular case 2. The amount of the elution component from the material of the fixing portion 3b is ideally half the amount of the elution component from the material of the fixing portions 3a and 3b. The balance of the permeated water generated in the ultrafiltration membrane module is discharged from the nozzle 6a as discharged water that is not used as ultrapure water. As a result, the mixing of the eluted component into the permeated water is reduced.

In reality, even if the amounts of outflow from the nozzle 6a and the nozzle 6b are equalized, the amounts of the elution components in the discharged water and the permeated water flowing out from both are not necessarily the same. For example, the opening degree of the valve V2 interposed in the discharge water pipe 102 is adjusted according to the flow rate of the water to be treated, the water recovery rate, the size of the ultrafiltration membrane module 10, and the like, and the nozzle 6a is used. By adjusting the ratio of the outflow amount from the nozzle 6b, it is possible to reduce the amount of the elution component from the material of the fixing portions 3a and 3b transferred to the permeated water. According to the ultrafiltration membrane module 10 having the above configuration, for example, the chloride ion (Cl-) concentration is 5 ng / L or less, more preferably 1 ng even when water to be treated having a temperature of 70 ° C. to 80 ° C. is passed through. Permeated water of / L or less can be obtained as ultrapure water from the nozzle 6b. Further, the chloride ion concentration in the permeated water is considered to be reduced to about 0.1 ng / L , although it depends on the lower limit of quantification of the measuring instrument.

For example, the outflow amount from the nozzle 6a (drainage water outflow pipe) and the nozzle 6b (permeate water outflow pipe) is the outflow amount L _t (cm) from the nozzle 6b with respect to the outflow amount L _c (cm ³ / h) from the nozzle 6a. As the value L _t / L _c of the ratio of ³ / h), 90/10 to 99/1 is preferable, and 95/5 to 98/2 is more preferable. The value L _t / L _c of the ratio of the outflow amount can be adjusted by adjusting the opening degree of the valve V2. Further, the value L _t / L _c of the ratio of the outflow amount may be adjusted by making the inner diameter of the outflow water outflow pipe smaller than the inner diameter of the permeation water outflow pipe. When L _t / L _c is in the above range, it is easy to reduce the amount of the eluted ion component in the permeated water.

In the ultrafiltration membrane module 10 of the present embodiment, the water recovery rate is preferably 90% or more, more preferably 95% or more. The operating differential pressure in the ultrafiltration membrane module 10 is preferably 0.1 MPa to 0.4 MPa. As a result, the retention of water in the ultrafiltration membrane module can be reduced, so that the amount of elution components transferred to the permeated water can be reduced.

Next, the ultrapure water production system 100 using the ultrafiltration membrane module of the above embodiment will be described with reference to FIG.

The ultrapure water production system 100 shown in FIG. 2 has a pretreatment unit 11, a primary pure water production unit 12, and a secondary pure water production unit 13. A tank 14 is connected between the primary pure water production unit 12 and the secondary pure water production unit 13.

The pretreatment unit 11 removes suspended solids in the raw water to generate pretreatment water, and supplies the pretreatment water to the primary pure water production unit 12. The pretreatment unit 11 is configured by appropriately selecting, for example, a sand filtration device, a microfiltration device, or the like for removing suspended solids in the raw water, and further includes a heat exchanger or the like that adjusts the temperature of the raw water as necessary. Be prepared to be configured. The pretreatment section 11 may be omitted depending on the quality of the raw water.

Raw water is, for example, city water, well water, groundwater, industrial water, water that has been recovered and pretreated (recovered water) that has been used in semiconductor manufacturing factories and the like.

The primary pure water production unit 12 includes a reverse osmosis membrane device, a degassing device (decarbonization, vacuum degassing device, degassing film device, etc.), an ion exchange device (cation exchange resin device, anion exchange resin device, and a mixture). It is configured by appropriately combining one or more of a floor type ion exchange resin device, etc., an electrodeionization device, etc.) and an ultraviolet oxidizing device. The primary pure water production unit 12 removes ionic components, non-ionic components, and dissolved gas in the pretreated water to produce primary pure water, and supplies the primary pure water to the tank 14. The primary pure water has, for example, a total organic carbon (TOC) concentration of 5 μg C / L or less and a resistivity of 17 MΩ · cm or more.

The primary pure water production unit includes, for example, a strongly basic anion exchange resin device, a 2B3T type device (strongly acidic cation exchange resin device, decarbonation tower, basic anion exchange device), a back-penetration film device, and ultraviolet oxidation. A configuration including an apparatus, a mixed bed type ion exchange resin apparatus, and a degassing membrane apparatus in order can be used.

The tank 14 stores the primary pure water. The pump P supplies the required amount to the secondary pure water production unit 13.

The secondary pure water production unit 13 removes trace impurities in the primary pure water to produce ultrapure water. As shown in FIG. 2, the secondary pure water production unit 13 has a heat exchanger (HEX) 34, an ultraviolet oxidizing device (TOC-UV) 35, and a hydrogen peroxide removing device on the upstream side of the ultrafiltration membrane device 30. (H ₂ O ₂ removing device) 36, an ultrafiltration membrane device (MDG) 37, and a non-regenerative mixed bed ion exchange resin device (Polisher) 38 are provided. The secondary pure water production unit 13 does not necessarily have to be equipped with the above-mentioned apparatus, and the above-mentioned apparatus may be used in combination as necessary.

The pump P pressurizes the primary pure water supplied from the tank 14 and supplies it to the heat exchanger (HEX) 34. The heat exchanger 34 controls the temperature of the primary pure water supplied from the tank 14 as needed. The temperature of the primary pure water whose temperature is controlled by the heat exchanger 34 is preferably 20 ° C. or higher and 30 ° C. or lower, and more preferably 22 ° C. or higher and 25 ° C. or lower.

The ultraviolet oxidizing device (TOC-UV) 35 irradiates the primary pure water temperature-controlled by the heat exchanger 34 with ultraviolet rays to decompose and remove trace organic substances in water. The ultraviolet oxidizing device 35 has, for example, an ultraviolet lamp and generates ultraviolet rays having a wavelength of around 185 nm. The ultraviolet oxidizing device 35 may further generate ultraviolet rays having a wavelength of around 254 nm. When water is irradiated with ultraviolet rays in the ultraviolet oxidizing device 35, the ultraviolet rays decompose the water to generate OH radicals, and the OH radicals oxidatively decompose organic substances in the water. In order to suppress the deterioration of the ultrafiltration membrane of the downstream ultrafiltration membrane device 30, the ultraviolet irradiation amount of the ultraviolet oxidation device 35 is preferably 0.05 to 0.2 kWh / m ³ .

The hydrogen peroxide removing device (H ₂ O ₂ removing device) 36 is a device that decomposes and removes hydrogen peroxide in water, for example, a palladium-supporting resin device that decomposes and removes hydrogen peroxide with a palladium (Pd) -supporting resin. , A reducing resin apparatus or the like, wherein the surface is filled with a reducing resin having a sulfurous acid group and / or a hydrogen peroxide group. By providing the hydrogen peroxide removing device 36, hydrogen peroxide in water can be reduced, so that deterioration of the ultrafiltration membrane device 30 and the second ultrafiltration membrane device 40 described later can be suppressed. ..

The degassing membrane device (MDG) 37 is a device that decompresses the secondary side of the gas permeable membrane and allows only the dissolved gas in the water flowing through the primary side to permeate to the secondary side to remove it. Specifically, as the degassing membrane device 37, commercially available products such as X-50 and X40 manufactured by 3M Corporation and Separel manufactured by DIC Corporation can be used. The degassing membrane device 37 removes the dissolved oxygen in the treated water of the hydrogen peroxide removing device 36 to generate, for example, treated water having a dissolved oxygen concentration (DO) of 1 μg / L or less.

The non-regenerative mixed bed type ion exchange resin device (Polisher) 38 has a mixed bed type ion exchange resin in which a cation exchange resin and an anion exchange resin are mixed, and a trace amount of a small amount in the treated water of the degassing film device 37 is provided. Adsorbs and removes cation and anion components.

The non-regenerative mixed bed type ion exchange resin device 38 has a strongly acidic cation exchange resin or a weakly acidic cation exchange resin as a cation exchange resin, and a strongly basic anion exchange resin or a weak as an anion exchange resin. Examples include basic anion exchange resins. As a commercially available mixed-bed ion exchange resin, for example, N-Lite MBSP and MBGP manufactured by Nomura Micro Science can be used.

The ultrafiltration membrane device 30 includes the ultrafiltration membrane module 10 of the above embodiment. The ultrafiltration membrane device 30 treats the treated water of the non-regenerative mixed bed type ion exchange resin device 38 to generate permeated water, concentrated water, and discharged water. In the ultrafiltration membrane device 30, the removal rate of fine particles having a particle diameter of 20 nm or more is preferably 99.8% or more, more preferably 99.95% or more, and more preferably 99.99% or more. More preferred. As a result, most of the fine particles that cause deterioration of the water quality of ultrapure water are removed by the ultrafiltration membrane device 30, and for example, the number of fine particles having a particle diameter of 50 nm or more is 500 pcs. / L or less, and even 200 pcs. Permeated water of / L or less can be obtained. The permeated water generated in the ultrafiltration membrane device 30 is supplied to the place of use (use point: POU) 50 of ultrapure water. The concentrated water is discharged to the outside of the system or circulated to the front stage of the ultrapure water production system 100 for reprocessing.

In the ultrapure water production system of the present embodiment, chlorine is adsorbed and removed by the non-regenerative mixed bed type ion exchange resin device 38, so that the chloride ion concentration in the water supplied to the ultrafiltration membrane device 30 is determined. For example, it can be 5 ng / L or less.

According to the ultrapure water production system 100 described above, the ultrafiltration membrane device 30 provided with the ultrafiltration membrane module 10 of the present embodiment is arranged at the most downstream of the secondary pure water production unit 13. Elution of contaminants from the ultrafiltration membrane module is significantly suppressed. Therefore, it is possible to obtain ultrapure water in which ionic components such as chloride ions are significantly reduced.

Further, as shown in FIG. 3, a second heat exchanger (HEX2) 41 and the ultrafiltration membrane of the above embodiment are further placed after the ultrafiltration membrane device 30 of the ultrapure water production system 100 shown in FIG. The second ultrafiltration membrane device (UF2) 40 provided with the module 10 may be arranged in order. In this case, for example, a branch pipe is connected to the permeation water outflow pipe of the ultrafiltration membrane device 30, and the second heat exchanger 41 and the second ultrafiltration membrane device 40 are arranged in the path of the branch pipe. , A part of the permeated water (ultrapure water) obtained by the ultrafiltration membrane device 30 can be passed through the second heat exchanger 41 and the second ultrafiltration membrane device (UF2) 40 in order. ..

When the second heat exchanger 41 and the second ultrafiltration membrane device 40 are used, the second heat exchanger 41 heats the treated water of the ultrafiltration membrane device 30 to 70 to 90 ° C. to obtain a second heat exchanger. It is preferable to supply to the ultrafiltration membrane device 40 of 2. As the second ultrafiltration membrane device 40, an apparatus having the same specifications as the above-mentioned ultrafiltration membrane apparatus 30 may be used, or an apparatus having different specifications may be used. Thereby, for example, warm ultrapure water heated to 70 to 90 ° C. can be obtained. The permeated water generated in the second ultrafiltration membrane device 40 is supplied to the place where the warm ultrapure water is used (use point: POU) 51. In this case, if the method of the present invention is not used, the amount of eluted components (contaminants) from the ultrafiltration membrane module tends to increase due to warm ultrapure water, but since the ultrafiltration membrane module of the embodiment is used. , The great effect of being able to obtain ultrapure water with significantly reduced ionic components such as chloride ions can be obtained. When the second ultrafiltration membrane device 40 is arranged, if the ultrafiltration membrane module of the above embodiment is used for the second ultrafiltration membrane device 40, the first ultrafiltration membrane device 30 will be described above. The ultrafiltration membrane module of the embodiment may be used, or the conventional ultrafiltration membrane module of both ends collecting type may be used.

The chloride ion concentration in the permeated water (ultrapure water) of the ultrafiltration membrane device 40 is, for example, 5 ng / L or less by suppressing the increase amount due to passing warm pure water through the ultrafiltration membrane device 40. More preferably, it can be maintained at 1 ng or less. Further, the number of fine particles having a particle diameter of 50 nm or more in the permeated water of the ultrafiltration membrane device 40 is, for example, 200 pcs. / L or less, preferably 50 pcs. / L or less.

(Second embodiment)
Next, a second embodiment of the present invention will be described.
The ultrafiltration membrane device and the ultrapure water production method according to the second embodiment basically have the same configuration in that the ultrafiltration membrane module described in the first embodiment is used, but are limited. The only difference is that the ultrafiltration module used in the ultrafiltration membrane device 30 has a two-stage configuration in which two ultrafiltration membrane modules are connected. That is, as shown in FIG. 4, the first ultrafiltration membrane module 30a and the second ultrafiltration membrane module 10 are connected to each other, or as shown in FIG. 5, the first ultrafiltration membrane module 30a is connected. The ultrafiltration membrane module 10 of the present embodiment can be used for both the filtration membrane module and the second ultrafiltration membrane module, and these can be connected to each other.

As the first ultrafiltration membrane module 30a shown in FIG. 4, a conventionally known ultrafiltration membrane module can be used without particular limitation, but here, a conventional ultrafiltration membrane module of a water collecting type at both ends is used. It exemplifies the case where there was. The ultrafiltration membrane module 30a has nozzles 32a and 32b and nozzles 36a and 36b, and a hollow fiber membrane made of an ultrafiltration membrane is housed therein. The water to be treated is introduced into the ultrafiltration membrane module 30a from the nozzle 32a connected to the water introduction pipe 113 to be treated to pass the water to be treated supplied to the ultrafiltration membrane device 30, and does not permeate the ultrafiltration membrane. The concentrated water is discharged from the concentrated water outflow pipe 111 connected to the nozzle 32b. On the other hand, the permeated water that has permeated the ultrafiltration membrane is discharged from the permeated water outflow pipes 114 connected to the nozzles 36b provided at both ends, and after all of them are merged, the second ultrafiltration membrane module 10 The water to be treated is introduced into the second ultrafiltration membrane module 10 from the nozzle 2a connected to the water pipe 103 to be treated.
The treatment in the second ultrafiltration membrane module is as described in the first embodiment. In this second ultrafiltration membrane module, concentrated water may be discharged, but it is also possible to close the valve V1 to perform total filtration.

Further, FIG. 5 illustrates a case where two ultrafiltration membrane modules of the present embodiment are used. Here, both the first ultrafiltration membrane module 10A and the second ultrafiltration membrane module 10B are the ultrafiltration membrane modules 10 of the present embodiment, and the flow of the water to be treated is described above. As described above, the water to be treated is introduced from the water pipes 103A and 103B to be treated, the concentrated water is discharged from the concentrated water pipes 101A and 101B, the discharged water is discharged from the discharge water pipes 102A and 102B, and the permeated water is discharged from the permeated water pipes 104A and 104B. It is leaked. In the present embodiment, the permeated water that has passed through the ultrafiltration membrane of the first ultrafiltration membrane module 10A is discharged from the permeation water pipe 104A connected to the nozzle 6b, and is directly discharged from the second ultrafiltration membrane module. The water to be treated of 10B is introduced into the second ultrafiltration membrane module from the nozzle 2a connected to the water pipe 103B to be treated. Then, as described with reference to FIG. 4, also in the configuration of FIG. 5, the treatment with the second ultrafiltration membrane module may cause the concentrated water to flow out, but the valve V1 is closed and the total amount is filtered. It is also possible to do.

With the configuration as shown in FIGS. 4 and 5, most of the fine particles are removed by the first ultrafiltration membrane module, and the load of fine particles by the second ultrafiltration membrane module is almost eliminated. It can be operated by filtration. By using total filtration, the recovery rate can be improved, and further, the yarn breakage of the hollow fiber membrane housed in the ultrafiltration membrane module can be suppressed.
Further, in this embodiment, the ultrafiltration membrane module has a two-stage configuration as described above, and the second ultrafiltration membrane module is the ultrafiltration membrane module described in the first embodiment. A great effect can be obtained that ultrapure water with significantly reduced ionic components such as chloride ions can be obtained.

In addition, in FIGS. 4 and 5, the ultrafiltration membrane module 10 of the present embodiment used as the second ultrafiltration module can be used upright with the nozzle 6a side in the vertical direction (downward).
In this case, the water to be treated is introduced from the nozzle 2a, which is the lower introduction pipe of the second outer module 10, and the permeated water that has passed through the hollow fiber membrane is obtained from the nozzle 6b in the vertical direction (upper), and the hollow fiber is obtained. The discharged water is allowed to flow out from the nozzle 6a in the vertical direction (downward) through the membrane. The concentrated water that does not permeate the hollow fiber membrane may be discharged from the nozzle 2b, but it is also possible to filter the entire amount without flowing out as described above.

The effect of total filtration is the same as described above, and thread breakage can be suppressed, but the following effects are also obtained. When the second ultrafiltration module 10 has an upright configuration, even if a thread breakage occurs in the hollow fiber membrane, the thread breakage is a fixing portion on the nozzle 2a side into which the water to be treated is introduced. It is likely to occur at the interface Fa of. In this case, the yarn breakage occurs downward, that is, on the outflow side of the discharged water. Therefore, the water to be treated in question will flow out from the nozzle 6a in the vertical direction (lower side) of the second ultrafiltration membrane module, and the treated water flowing out from the nozzle 6b in the vertical direction (upper side) will be affected. The quality of treated water can be stably secured without any problems.

Next, an embodiment will be described. The present invention is not limited to the following examples.

(Manufacturing of warm pure water)
Water treatment was performed as follows using an external pressure type ultrafiltration membrane module (OLT-6036VA manufactured by Asahi Kasei Co., Ltd.). The external pressure type ultrafiltration membrane module using both ends of the water collection type used in this example has the same three-dimensional structure as that of FIG. 1, and the water to be treated is introduced from the nozzle 2a and the concentrated water is discharged from the nozzle 2b. Is designed to collect permeated water from both the nozzle 6a and the nozzle 6b.

The specifications of OLT-6036VA manufactured by Asahi Kasei Corporation are as follows.
Hollow fiber membrane inner diameter 0.6 mm
Effective film area 34m ²
Module (cylindrical case) inner diameter 172 mm
Module (cylindrical case) length 1177 mm
Nominal fraction molecular weight of ultrafiltration membrane 6000
Maximum film inner / outer surface differential pressure 300 kPa (25 ° C)

An ultrapure water production system having a secondary pure water production unit 13 similar to the ultrapure water production system shown in FIG. 3 was used. This secondary pure water production unit has a first heat exchanger, an ultraviolet oxidizing device (JPW-2 manufactured by Nippon Photo Science Co., Ltd.), and a palladium (Pd) -supported resin device (LANXESS) downstream of the tank that stores the primary pure water. Lewattit K7333), degassing membrane device (3M, X40 G451H), non-regenerative mixed bed ion exchange device (200L filled with Nomura Micro Science N-Lite MBSP), the above ultrafiltration membrane It is equipped with an appliance (OLT-6036VA manufactured by Asahi Kasei Co., Ltd.), and is further equipped with a second heat exchanger in order. In the first heat exchanger, the temperature of the primary pure water was adjusted to 23 ± 3 ° C., and in the second heat exchanger, the permeated water of the ultrafiltration membrane device was heated to 80 ° C. In the ultrafiltration membrane module placed in the ultrafiltration membrane device used in the production of warm pure water, permeated water was collected by the water collection method at both ends. The water quality of the obtained warm pure water has a specific resistivity of 17 MΩ · cm or more, a TOC concentration of 5 μg C / L or less, and a particle size of 50 μm or more of 200 pcs. About / L, the chloride ion concentration was 25 ng / L.

(Example 1)
An ultrafiltration membrane module that has basically the same structure as the above-mentioned external pressure type ultrafiltration membrane module that collects both ends, but allows permeated water to flow out from the nozzle 6b and discharged water from the nozzle 6a to collect water from one side. From the nozzle 2a arranged on the side surface of the tubular case, the warm pure water (pure water heated to 80 ° C.) obtained above was introduced into the ultrafiltration membrane module and filtered by an external pressure method. The opening degree of the valve V1 was set so that the amount of concentrated water flowing out from the nozzle 2b was 3% with respect to the flow rate (m ³ / h) of the primary pure water supplied from the nozzle 2a. In addition, of the water that has passed through the ultrafiltration membrane, the flow rate that flows out as discharged water from the nozzle 6a is 2% of the total flow rate that flows out from the nozzles 6a and 6b, and the amount of permeated water that collects from the nozzle 6b is 98. The opening degree of the valve V2 was set so as to be%.

The ultrafiltration membrane module was used by standing upright with the nozzle 6a side in the vertical direction (downward). The chloride ion concentration (as Cl) in the permeated water was measured with respect to the time from the start of supply of warm pure water into the ultrafiltration membrane module. The results are shown in Table 1. The chloride ion concentration was measured by ion chromatography (Dionex ICS-5000, manufactured by Thermo Fisher Scientific).

(Comparative example)
Using the above-mentioned external pressure type ultrafiltration membrane module with both ends collecting water, the warm pure water (pure water heated to 80 ° C.) obtained above is introduced into the ultrafiltration membrane module from the nozzle 2a in the same manner as in Example 1. did. However, the concentrated water is discharged from the nozzle 2b at the same flow rate as that of the first embodiment (concentrated water outflow amount is 3% with respect to the flow rate of the supplied primary pure water), and the nozzles 6a arranged at both ends of the ultrafiltration membrane module. Permeated water was collected from both and 6b. Similar to Example 1, the change over time in the chloride ion concentration (as Cl) in the permeated water with respect to the number of days from the start of supply of warm pure water into the ultrafiltration membrane module was measured. The results are shown in Table 1. Moreover, the time course of the chloride ion concentration of Example 1 and Comparative Example is shown in the graph of FIG.

(Example 2)
In the first embodiment, by setting the opening degree of the valve V2, the flow rate discharged from the nozzle 6a as discharged water is in the range of 0% to 10% with respect to the total flow rate flowing out from the nozzle 6a and the nozzle 6b. The permeated water was collected from the nozzle 6b. 55 days after the start of water flow of warm pure water to the ultrafiltration membrane module, the chloride ion concentration (as Cl) in the obtained permeated water was measured. The results are shown in Table 2. Further, the relationship between the permeated water drainage flow rate ratio and the chloride ion concentration in the permeated water in Example 2 is shown in the graph of FIG. 7.

1 ... Hollow fiber membrane, 2 ... Cylindrical case, 2a, 2b ... Nozzle, 3a, 3b ... Fixed part, 4 ... Heat exchanger (HEX), 6a, 6b ... Nozzle, 60a, 60b ... Piping connection cap, 61a, 61b ... Contact part, 101 ... Concentrated water pipe, 102 ... Drain water pipe, 103 ... Water pipe to be treated, 104 ... Permeated water pipe, V1, V2 ... Valve, 11 ... Pretreatment part, 12 ... Primary pure water production part, 13 ... Sub-pure water production unit, 14 ... tank, 34,41 ... heat exchanger (HEX), 35 ... ultraviolet oxidizing device (TOC-UV), 36 ... hydrogen peroxide removing device (H ₂ O ₂ removing device), 37 ... Degassing membrane device, 38 ... non-regenerative mixed bed ion exchange resin, 30, 40 ... ultrafiltration membrane device, 50, 51 ... use point (POU), 100 ... ultrapure water production system, P ... pump.

Claims (6)

An ultrafiltration membrane module composed of a plurality of hollow fiber membranes made of an ultrafiltration membrane, a tubular case accommodating the plurality of hollow fiber membranes, and an ultrafiltration membrane module.
The tubular case is provided on the outer peripheral surface thereof with a first nozzle and a second nozzle arranged apart from each other in the axial direction of the tubular case, and at both ends of the tubular case. Axial direction of the tubular case so that the opening ends of the plurality of hollow fiber membranes of the third nozzle and the fourth nozzle and the plurality of hollow fiber membranes face each of both ends of the tubular case. The tubular shape is fixed at each position between one end of the tubular case and the first nozzle and between the other end of the tubular case and the second nozzle. With a pair of fixing parts to seal the case,
The first nozzle is a water to be treated introduction pipe for introducing water to be treated, and the second nozzle is a concentrated water outflow pipe for flowing out concentrated water that does not permeate the hollow fiber membrane.
The third nozzle is a permeation water outflow pipe that discharges the permeated water that has permeated the hollow fiber membrane, and the fourth nozzle is a drainage water outflow pipe that discharges the drainage water that has permeated the hollow fiber membrane. can be,
The value of the ratio of the outflow amount from the permeated water outflow pipe to the outflow amount from the outflow water outflow pipe (outflow amount from the permeated water outflow pipe / outflow amount from the outflow water outflow pipe) is 90/10 or more and 99 /. An ultrafiltration membrane module having a flow ratio adjusting means for obtaining only the permeated water flowing out of the permeated water outflow pipe as ultrapure water, which is 1 or less. The ultrafiltration membrane module according to claim 1, wherein the permeated water outflow pipe is provided closer to the concentrated water outflow pipe than the treated water introduction pipe. The ultrafiltration membrane module according to claim 1 or 2, wherein the fixing portion is made of an epoxy resin. An ultrafiltration membrane module composed of a plurality of hollow fiber membranes made of an ultrafiltration membrane, a tubular case accommodating the plurality of hollow fiber membranes, and an ultrafiltration membrane module.
The tubular case is provided on the outer peripheral surface thereof with a first nozzle and a second nozzle arranged apart from each other in the axial direction of the tubular case, and at both ends of the tubular case. With the third nozzle and the fourth nozzle,
The plurality of hollow fiber membranes are fixed along the axial direction of the tubular case so that the open ends of the plurality of hollow fiber membranes face each of both ends of the tubular case, and the tubular shape is formed. A pair of fixing portions that seal the tubular case at each position between one end of the case and the first nozzle and between the other end of the tubular case and the second nozzle. In the ultrafiltration module equipped with
The water to be treated is introduced into the ultrafiltration membrane module from the first nozzle, and the concentrated water that does not permeate the hollow fiber membrane is discharged from the second nozzle.
The permeated water that has permeated the hollow thread film from the third nozzle of the tubular case and the discharged water that has permeated the hollow thread film from the fourth nozzle are the permeated water with respect to the outflow amount of the discharged water. The characteristic is that the value of the ratio of the outflow amount (permeated water outflow amount / discharged water outflow amount) is 90/10 or more and 99/1 or less, and only the permeated water is obtained as ultrapure water. Ultrapure water production method. The ultrapure water production method according to claim 4 , wherein the chloride ion (Cl ⁻ ) concentration in the permeated water of the ultrafiltration membrane module is 5 ng / L or less (as Cl). Chloride ion (Cl) in the permeated water of the ultrafiltration membrane module ^- ) The method for producing ultrapure water according to claim 4, wherein the concentration is 1 ng / L or less (as Cl).

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