JP5670069B2 - Pure water production system - Google Patents

Description

  The present invention relates to a pure water production system, and more particularly to a pure water production system including a reverse osmosis membrane device.

  High purity pure water not containing impurities is used in semiconductor manufacturing processes, electronic component manufacturing, medical instrument cleaning, and the like, and various types of pure water manufacturing systems have been provided. Moreover, many things provided with the ion exchange apparatus using an ion exchange resin and the reverse osmosis membrane apparatus using a reverse osmosis membrane are provided as a pure water manufacturing system.

  The ion exchange device is equipped with a cation exchange resin or an anion exchange resin and adsorbs and removes fixed ions in the ion exchange resin and ions with different signs. There is also provided a mixed bed type ion exchange apparatus in which an exchange resin and an OH type anion exchange resin are mixed and filled.

  The reverse osmosis membrane device is a device that removes ions in the supply water by membrane separation using a reverse osmosis membrane (RO membrane). For example, Patent Document 1 below discloses a pure water production system that includes a reverse osmosis membrane device and a mixed bed type ion exchange device installed in a subsequent stage.

  Patent Document 2 below discloses a pure water production system including a reverse osmosis membrane device arranged in series in two stages and an electrodeionization device arranged in a subsequent stage.

JP 2000-070933 A JP 2004-167423 A

  However, when the reverse osmosis membrane device and the mixed bed type ion exchange device are combined as in Patent Document 1, both the cation exchange membrane resin and the anion exchange membrane resin are used in the mixed bed type ion exchange device. Regeneration is required, which increases the labor and cost of regeneration.

  Moreover, if an electrodeionization apparatus is combined like the said patent document 2, an electrodeionization apparatus will be maintenance-free over a long period of time by electrically deionizing combining an ion exchange membrane and an ion exchange resin. The regeneration of the ion exchange resin can be performed. Therefore, although the labor and cost of regeneration can be reduced, the price of the electrodeionization apparatus is higher than that of the mixed bed ion exchange apparatus, so that the pure water production system becomes very expensive.

  This invention is made | formed in view of such a subject, In the pure water manufacturing system using a reverse osmosis membrane apparatus, the pure water manufacturing system which can manufacture high-pure pure water at low cost is provided. For the purpose.

In order to solve the above-mentioned problems, a pure water production system according to the present invention has a positively charged or negatively charged reverse osmosis membrane and produces permeated water and concentrated water by membrane separation treatment of supplied water. Only the reverse osmosis membrane device of the stage and the ion exchanger having fixed ions having the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane device in the final stage are supplied with the permeated water of the reverse osmosis membrane device. The reverse osmosis membrane device comprises three stages of a first reverse osmosis membrane device, a second reverse osmosis membrane device and a third reverse osmosis membrane device, and the second and second The reverse osmosis membrane in the three reverse osmosis membrane devices is negatively charged .
The pure water production system according to the present invention has a positively charged or negatively charged reverse osmosis membrane, and has two or more stages of reverse osmosis membranes for producing permeated water and concentrated water by membrane separation treatment of the supplied water. A single ion exchange apparatus having only an ion exchanger having fixed ions of the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane apparatus in the final stage, and supplied with the permeated water of the reverse osmosis membrane apparatus The reverse osmosis membrane device comprises two stages of a first reverse osmosis membrane device and a second reverse osmosis membrane device in which the reverse osmosis membrane is a negative charge type, and the first reverse osmosis membrane device or the It is characterized by further comprising an alkali addition device that adjusts the pH to 9 or more by adding an alkali to the supply water in the previous stage of the second reverse osmosis membrane device.
The pure water production system according to the present invention has a positively charged or negatively charged reverse osmosis membrane, and has two or more stages of reverse osmosis membranes for producing permeated water and concentrated water by membrane separation treatment of the supplied water. A single ion exchange apparatus having only an ion exchanger having fixed ions of the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane apparatus in the final stage, and supplied with the permeated water of the reverse osmosis membrane apparatus The reverse osmosis membrane device is composed of two stages, a first reverse osmosis membrane device and a second reverse osmosis membrane device, and is arranged in front of the first reverse osmosis membrane device or the second reverse osmosis membrane device. And an acid addition device for adjusting the pH to 6 or less by adding an acid to the supply water, and a deaeration device for supplying the supply water whose pH is adjusted by the acid addition device.

  The pure water production system according to the present invention can produce high-purity pure water at low cost.

Drawing 1 is a mimetic diagram showing roughly the composition of the pure water manufacturing system concerning a first embodiment. FIG. 2 is a schematic diagram schematically showing a configuration of a pure water production system according to Modification 1 of the first embodiment. FIG. 3 is a schematic diagram schematically showing the configuration of the pure water production system according to the second embodiment. FIG. 4 is a schematic diagram schematically showing the configuration of the pure water production system according to the third embodiment. FIG. 5 is a schematic diagram schematically showing a configuration of a pure water production system according to Modification 2 of the third embodiment. FIG. 6 is a schematic diagram schematically showing a configuration of a pure water production system according to the fourth embodiment. FIG. 7 is a schematic diagram schematically showing a configuration of a pure water production system according to Modification 3 of the fourth embodiment.

(First embodiment)
Hereinafter, a pure water production system according to an embodiment of the present invention will be described with reference to the drawings. Drawing 1 is a mimetic diagram showing roughly the composition of the pure water manufacturing system concerning a first embodiment. As shown in the figure, the pure water production system 10 includes a soft water device 11 and a first reverse osmosis membrane device (hereinafter, “reverse osmosis membrane device” is referred to as an “RO device”) installed in order on the water supply line 2. 15. A second RO device 18 having a negative membrane charge and a cation exchange device 19 are provided.

  In the water softener 11, a sodium-type cation exchange resin is accommodated in an ion exchange tower. When the raw water is supplied from the supply line 2 to the soft water device 11, the calcium ions and magnesium ions, which are hardness components contained in the raw water, are ion-exchanged with sodium ions of the cation exchange resin and removed, and the raw water is softened. . That is, the first RO device 15 is provided with soft water produced by the soft water device 11 as supply water.

  The first RO device 15 and the second RO device 18 have a built-in RO membrane module, and pressurize the supply water side with a pressure pump (not shown) to allow only water molecules to permeate the RO membrane, and ionize by the RO membrane. Is removed. That is, the first RO device 15 and the second RO device 18 perform membrane separation processing of the supplied water with the RO membrane, and produce permeated water from which ions in the supplied water are removed and concentrated water in which the ions in the supplied water are concentrated. To do. Concentrated water is appropriately discharged out of the system. The second RO device 18 is provided with the permeated water produced by the first RO device 15 as supply water.

  The membrane charge of the first RO device 15 may be positive or negative. In the case of a positively charged membrane, in the RO composite membrane in which a thin skin layer is formed on the ultrafiltration membrane (UF membrane) by a method such as interfacial crosslinking, for example, a cation group such as a quaternary ammonium group What is necessary is just to use what charged the surface of the film | membrane positively by introduce | transducing. In addition, when using a negatively charged membrane as the RO device, in the RO composite membrane, for example, a polyamide type negatively charged membrane in which an anionic group such as a carboxyl group is introduced to negatively charge the membrane surface is used. Good.

  The second RO device 18 is, for example, a polyamide negative electrode membrane. The RO membrane used in this embodiment preferably has a salt removal rate of 95% or more, and more preferably 99% or more. RO membranes having such a salt removal rate may be classified into low-pressure RO membranes, ultra-low pressure RO membranes, ultra-low pressure RO membranes, etc. depending on the operating pressure, but any type of RO membrane may be used. .

  The cation exchange device 19 includes a weakly acidic cation exchange resin. That is, the cation exchange tree device 19 has only an ion exchanger having negative fixed ions (ion exchange groups) having the same sign as the negative charge of the second RO device 18, and is manufactured by the second RO device 18. The cation contained in the permeated water is removed.

  Although the configuration of the pure water production system 10 according to the first embodiment has been described above, the hardness component of the raw water supplied to the pure water production system 10 is first removed in the soft water device 11. Subsequently, in the first RO device 15 which is the first-stage RO device, impurities including ions in the supply water are removed. At this time, since the ion concentration of the supply water (soft water) to the first RO device 15 is high, the influence of the membrane charge of the first RO device 15 hardly occurs.

  On the other hand, since the ion concentration of the permeated water of the first RO device 15 becomes extremely dilute, in the second RO device 18 that is the second-stage RO device, the charge (negative) of the RO membrane and the cation with the opposite sign are transmitted. The permeated water of the second RO device 18 has a water quality rich in cations.

  On the other hand, the cation exchange device 19 having only the ion exchanger having the fixed ions having the same sign as the charge (negative) of the RO membrane of the second RO device 18 which is the final RO device is the second RO device 18. By installing it on the downstream side, the cations remaining in the permeated water of the second RO device 18 can be removed, and high-purity pure water can be obtained.

  As described above, according to the present embodiment, the permeated water from which ions have been once removed by the first RO device 15 further includes the second RO device 18 having a negative charge membrane and the RO membrane of the final stage RO device. High-purity pure water can be obtained by processing with the cation exchange device 19 that adsorbs ions of different signs and ions of different signs. In addition, such a system can greatly reduce the regeneration cost as compared with the conventional case where a mixed bed ion exchange apparatus is used.

  In the first embodiment, the RO device installed on the upstream side of the second RO device 18 which is the final stage RO device is the first RO device 15 alone, but the RO device is further installed and the second RO device is installed. A plurality of RO devices may be installed in multiple stages on the front side of 18. As for the RO device to be added, the membrane charge may be either positive or negative, similarly to the first RO device 15.

  Subsequently, Modification 1 of the first embodiment will be described. FIG. 2 is a schematic diagram schematically showing a configuration of a pure water production system according to the first modification. As shown in the figure, the pure water production system 20 includes a soft water device 11, a first RO device 15, a second RO device 28 with positive membrane charge, and an anion exchange device 29 installed on the water supply line 2. I have.

  In the first modification, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. The pure water production system 20 is different from the pure water production system 10 in that it includes a second RO device 28 of a positively charged membrane and an anion exchange device 29 in the subsequent stage.

  The anion exchange device 29 includes a weak alkali type anion exchange resin. That is, the anion exchange device 29 has only an ion exchanger having positive fixed ions having the same sign as the positive charge of the second RO device 28 and is included in the permeated water produced by the second RO device 18. To remove anions.

  Since the ion concentration of the permeated water of the first RO device 15 is dilute, the cations in the supply water are removed by the positively charged RO membrane of the second RO device 28, whereas the anions are the RO membrane. Easy to penetrate. The permeated anions are removed by an anion exchange device 29 that adsorbs ions of a different sign from the charge of the RO membrane of the second RO device 28.

  As described above, also in the first modification, an anion exchange device 29 that adsorbs ions with opposite signs and charges (positive) of the RO membrane is installed on the second RO device 28 in the final stage of the system. Thus, the cation and anion components can be removed well and high-purity pure water can be produced at low cost.

(Second embodiment)
Next, a second embodiment of the present invention will be described. FIG. 3 is a schematic diagram schematically showing the configuration of the pure water production system according to the second embodiment. As shown in the figure, the pure water production system 30 includes a soft water device 31, a first RO device 35, a second RO device 36 with negative membrane charge, and a negative membrane charge. The third RO device 38 and the cation exchange device 39 are provided.

  The membrane charge of the first RO device 35 may be positive or negative, and the configurations of the soft water device 31, the RO devices 35, 36, and 38, and the cation exchange device 39 are the same as in the first embodiment. Detailed description is omitted. In the second embodiment, the RO devices 36 and 38 having negatively charged RO membranes are continuously arranged, and the cation exchange device 39 for adsorbing negatively charged ions and negative ions of the RO membrane in the subsequent stage thereof. It is characterized by installing.

  In this embodiment, when the permeated water from which ions are removed by the first RO device 35 and the ion concentration is diluted is processed by the negatively charged second RO device 36, the permeated water is affected by negative membrane charge. Makes it more alkaline.

Here, the abundance ratio of the carbonic acid component in water is determined by the pH of the water. When the pH is 6 or less, the presence of dissolved carbon dioxide (CO ₂ ) is dominant, and at pH 6.5-10, bicarbonate ions (HCO ₃ ^- ) Is dominant, and at pH 10.5 or higher, the presence of carbonate ions (CO ₃ ²⁻ ) is dominant. Further, in the RO apparatus, hydrogen carbonate ions and carbonate ions, which are ions, can be removed, but dissolved carbon dioxide gas cannot be removed. Therefore, in order to remove the carbonic acid component with the RO device, it is necessary to ionize the carbonic acid component by increasing the pH of the water supplied to the RO device.

  As described above, when the treated water of the second RO device 36 becomes alkaline and ionization of the carbonic acid component contained in the water supplied to the third RO device 38 is promoted, the third RO device 38 having a negative membrane charge. Thus, the carbonic acid component can be efficiently removed, and the removal rate of the carbonic acid component can be improved.

  Furthermore, since the permeated water of the third RO device 38 has a cation-rich water quality due to the negative membrane charge, the remaining cation is removed by the cation exchange device 39 installed in the subsequent stage, High purity pure water can be obtained.

  As described above, according to the present embodiment, as in the first embodiment, the second and third RO devices 36 and 38 of the negative electrode membrane are further applied to the permeated water from which impurities are once removed by the first RO device 35. Then, the high-purity pure water can be obtained by processing with the charge (negative) of the RO membrane of the RO device in the final stage and the cation exchange device 39 that adsorbs ions of different signs.

  Furthermore, in the present embodiment, the permeated water is made alkaline by the influence of the negative membrane charge of the second RO device 36, and the decarboxylation effect is also achieved by promoting the ionization of the carbonic acid component. Pure water can be obtained.

  In addition, in order to ionize a carbonic acid component more effectively and to remove it effectively, it is desirable to comprise so that pH of the water supply to the 3rd RO apparatus 38 may be adjusted to 6.5 or more, More desirably, dissolved carbon dioxide gas It is good to comprise so that pH may be adjusted to 9 or more so that substantially no exists.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 4 is a schematic diagram schematically showing the configuration of the pure water production system according to the third embodiment. As shown in the figure, a pure water production system 40 includes a soft water device 41 installed in order on the water supply line 2, an alkali addition device 42 for adding alkali to the water supply line 2, a first RO device 45, a membrane charge. The second RO device 48 and the cation exchange device 49 are negative.

  The membrane charge of the first RO device 45 may be positive or negative, and the configurations of the water softening device 41, the RO devices 45 and 48, and the cation exchange device 49 are the same as those in the first embodiment, and detailed description thereof is omitted. . The third embodiment is characterized in that alkali is added to the water supplied to the first RO device 45 by the alkali adding device 42.

  The alkali addition device 42 is a device that makes water flowing through the water supply line 2 alkaline, and uses, for example, a device that adds an alkaline aqueous solution such as sodium hydroxide, an ion exchange tower that contains an OH-type anion exchange resin, or the like. be able to. As described above, in order to ionize the carbonic acid component effectively and remove it with the RO membrane, it is desirable to adjust the pH to 6.5 or higher, more preferably pH 9 or higher by the alkali addition device 42.

  In the present embodiment, ionization of the carbonic acid component contained in the supply water can be promoted by adding alkali to the supply water to the first RO device 45. The ionized carbonic acid component can be efficiently removed by the second RO device 48 in which the ion concentration becomes dilute and the influence of membrane charging appears.

  Furthermore, since the permeated water of the second RO device 48 has a cation rich water quality due to the negative membrane charge, the remaining cation is removed by the cation exchange device 49 installed in the subsequent stage, High purity pure water can be obtained.

  As described above, according to the present embodiment, in the same manner as in the first embodiment, the second RO device 48 of the negatively charged membrane and the final stage are further applied to the permeated water from which ions have been once removed by the first RO device 45. High purity pure water can be obtained by processing with the charge (negative) of the RO membrane of the RO device and the cation exchange device 49 that adsorbs ions of different signs.

  Furthermore, in the present embodiment, the alkali addition device 42 makes the supply water alkaline and promotes the ionization of the carbonic acid component, thereby also exerting a decarboxylation effect and obtaining pure water with higher purity. it can.

  Then, the modification 2 of 3rd embodiment is demonstrated. FIG. 5 is a schematic diagram schematically showing a configuration of a pure water production system according to Modification 2. As shown in the figure, the pure water production system 50 includes a soft water device 41, a first RO device 45, an alkali addition device 42, a second RO device 48, and a cation exchange device 49 installed on the water supply line 2. ing.

  Since this modification 2 is only the change of the installation positions of the first RO device 45 and the alkali addition device 42 as compared with the third embodiment shown in FIG. A description thereof will be omitted.

  Also in the second modification, by adding alkali to the supply water to the second RO device 48, ionization of the carbonic acid component contained in the supply water can be promoted, and the same effect as the third embodiment is obtained. Play.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 6 is a schematic diagram schematically showing a configuration of a pure water production system according to the fourth embodiment. As shown in the figure, a pure water production system 60 includes a soft water device 61 installed on the water supply line 2, an acid addition device 62 for adding acid to the water supply line 2, a deaeration device 63, and a first RO device. 65, a second RO device 68 having a negative membrane charge, and a cation exchange device 69.

  The membrane charge of the first RO device 65 may be positive or negative, and the configurations of the water softening device 61, the RO devices 65 and 68, and the cation exchange device 69 are the same as those in the first embodiment, and thus will be described in detail. Is omitted. The fourth embodiment is characterized in that acid is added to the water supplied to the first RO device 65 by the acid addition device 62 and decarboxylation is performed by the deaeration device 63.

  The acid addition device 62 is a device that acidifies the water flowing through the water supply line 2. For example, a pH adjustment tank with a stirring member for adding hydrochloric acid or sulfuric acid is installed, or a static mixer is installed in the water supply line 2. And an acid inlet can be installed on the upstream side.

  Here, as described above, the existence ratio of the carbonic acid component in the water becomes dominant when the water is acidified and the pH becomes 6 or less. Therefore, as will be described later, in order to efficiently remove the dissolved carbon dioxide gas by the degassing device 63, the pH of the water supplied to the degassing device 63 becomes 6 or less by the acid addition by the acid addition device 62. It is more desirable to configure.

  The degassing device 63 is a device that removes dissolved gas in the feed water, and a vacuum degassing device, a nitrogen substitution degassing device, a membrane degassing device, or the like can be used.

  In the present embodiment, the supply water that has been softened by adding acid by the acid addition device 62 is oxidized, so that most of the carbonic acid component in the supply water becomes dissolved carbon dioxide gas. By caring, the carbonic acid component in the feed water can be efficiently decarboxylated.

  Further, when the ion concentration of the carbonic acid component remaining in the supply water is diluted by the first RO device 65, the ionization is promoted. And since this ionized carbonic acid component is removed by the 2nd RO apparatus 68 of a negative electrode membrane, in this embodiment, the removal rate of the carbonic acid component in the whole system can be improved greatly.

  As described above, according to the present embodiment, in the same manner as in the first embodiment, the second RO device 68 of the negatively charged membrane and the final stage of the permeated water from which impurities have been once removed by the first RO device 65 are provided. High purity pure water can be obtained by processing with the charge (negative) of the RO membrane of the RO device and the cation exchange device 69 that adsorbs ions of different signs. Furthermore, in this embodiment, the removal rate of a carbonic acid component can be greatly improved by adding an acid to the supply water to the 1st RO apparatus 65 and performing a deaeration process.

  Subsequently, Modification 3 of the fourth embodiment will be described. FIG. 7 is a schematic diagram schematically showing a configuration of a pure water production system according to Modification 3. As shown in the figure, the pure water production system 70 includes a soft water device 61, a first RO device 65, an acid addition device 62, a deaeration device 63, and a second membrane charge that are negative on the water supply line 2. An RO device 68 and a cation exchange device 69 are provided.

  Compared with the fourth embodiment shown in FIG. 6, the third modification is merely the change in the installation position of the first RO device 65 to the upstream side of the acid addition device 62. The same numbers are assigned and the description is omitted.

  Also in the third modification, by adding an acid to the supply water to the second RO device 68 and performing a deaeration process, the removal rate of the carbonic acid component can be greatly improved, which is the same as in the fourth embodiment. Has an effect.

  As mentioned above, although 1st thru | or 4th embodiment of this invention was described in detail, embodiment of this invention is not limited to the form mentioned above, In the range which does not deviate from the main point of this invention, a various deformation | transformation is carried out. Is possible. For example, it goes without saying that another configuration having the same function can be adopted as the configuration of each device described above.

2 Water supply line 10, 20, 30, 40 Pure water production system 50, 60, 70 Pure water production system 11, 31, 41, 61 Soft water device 15, 35, 45, 65 First RO device 18, 28, 36, 48 Second RO device 68 Second RO device 38 Third RO device 19, 39, 49, 69 Cation exchange device 29 Anion exchange device 42 Alkali addition device 62 Acid addition device 63 Deaeration device

Claims (3)

A reverse osmosis membrane device having two or more stages, which has a positively charged or negatively charged reverse osmosis membrane and produces permeated water and concentrated water by subjecting the supplied water to membrane separation;
A single ion exchange device having only an ion exchanger having a fixed ion of the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane device in the final stage, to which the permeated water of the reverse osmosis membrane device is supplied. Prepared ,
The reverse osmosis membrane device comprises three stages of a first reverse osmosis membrane device, a second reverse osmosis membrane device and a third reverse osmosis membrane device,
The pure water production system, wherein the reverse osmosis membranes in the second and third reverse osmosis membrane devices are negatively charged . A reverse osmosis membrane device having two or more stages, which has a positively charged or negatively charged reverse osmosis membrane and produces permeated water and concentrated water by subjecting the supplied water to membrane separation;
A single ion exchange device having only an ion exchanger having a fixed ion of the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane device in the final stage, to which the permeated water of the reverse osmosis membrane device is supplied. Prepared ,
The reverse osmosis membrane device is composed of two stages of a first reverse osmosis membrane device and a second reverse osmosis membrane device in which the reverse osmosis membrane is a negative charge type,
A pure water production system , further comprising an alkali addition device for adjusting pH to 9 or more by adding an alkali to the supply water in a preceding stage of the first reverse osmosis membrane device or the second reverse osmosis membrane device . A reverse osmosis membrane device having two or more stages, which has a positively charged or negatively charged reverse osmosis membrane and produces permeated water and concentrated water by subjecting the supplied water to membrane separation;
A single ion exchange device having only an ion exchanger having a fixed ion of the same sign as the charge of the reverse osmosis membrane in the reverse osmosis membrane device in the final stage, to which the permeated water of the reverse osmosis membrane device is supplied. Prepared ,
The reverse osmosis membrane device is composed of two stages, a first reverse osmosis membrane device and a second reverse osmosis membrane device,
An acid addition device that adjusts the pH to 6 or less by adding an acid to the feed water before the first reverse osmosis membrane device or the second reverse osmosis membrane device, and a feed water whose pH is adjusted by the acid addition device And a deaeration device to which water is supplied .

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