JP3979890B2 - Operation method for producing deionized water - Google Patents
Operation method for producing deionized water Download PDFInfo
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- JP3979890B2 JP3979890B2 JP2002191020A JP2002191020A JP3979890B2 JP 3979890 B2 JP3979890 B2 JP 3979890B2 JP 2002191020 A JP2002191020 A JP 2002191020A JP 2002191020 A JP2002191020 A JP 2002191020A JP 3979890 B2 JP3979890 B2 JP 3979890B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、電気式脱イオン水製造装置にて半導体製造分野、発電所分野、ボイラー分野、製薬分野や研究施設等で用いられる純水、脱イオン水を効率的に製造する運転方法に関する。
【０００２】
【従来の技術】
近年、脱イオン水の製造方法として従来のイオン交換樹脂の欠点を改善した電気式脱イオン法が開発され実用化されている。この方法は陽極を備える陽極室陰極を備える陰極室との間にカチオン交換膜とアニオン交換膜を交互に配し、この両膜の間に脱塩室と濃縮室を交互に形成した電気透析装置の脱塩室に、イオン交換樹脂を充填し、電圧を印加しながら、被処理水を脱塩室に流入させ、濃縮室には、被処理水又は濃縮水の一部を濃縮水として流入させる事で脱塩室を脱イオンするものである。この方法では、イオン交換体が連続的に再生されるので、酸やアルカリ等の薬剤での再生が不要となる。
【０００３】
しかしながら、運転停止時は、濃縮室と脱塩室との濃度差により濃縮液から隔膜であるイオン交換膜を介して脱塩室側にＮａＣｌ等の塩分が移動する。その為、脱塩室に充填されているイオン交換体は、運転中は、再生型に維持されていたのが、負荷型となり、汚染される。その為、運転開始時は、脱塩室のイオン交換体が、再生型へ変化するまで、脱イオン水の水質や電導度は、安定せず、その間の水及び電気代がロスとなる。この様に、運転開始時は、安定運転までの立ち上がりに時間がかかり、水利用率の低下や電気代の運転コストＵＰを招く。
【０００４】
【発明が解決しようとする課題】
本発明は、運転開始時の水利用率の低下や電気代の運転コストＵＰの効率低下を改善した運転方法を提案するものである。
【０００５】
【課題を解決するための手段】
本発明者らは、運転開始時の水利用率の低下や電気代の運転コストＵＰのロスを最小限に抑える方法について、種々検討を重ねた結果、運転停止時の停止方法を工夫する事で、目的を達する事を見出し本発明を完成するに至った。
即ち、本発明は、以下の通りである。
（１）陽極室と陰極室の間にカチオン交換膜とアニオン交換膜を交互に配し、この両膜の間に脱塩室と濃縮室を交互に形成した、電気透析装置の少なくとも脱塩室にイオン交換体を充填した電気式脱イオン水製造装置に被処理水を流して脱イオン水を製造する運転方法において、脱イオン水を製造後の前記陽極陰極間の印加電圧を停止後に、前記濃縮室に濃縮液の電気電導度より低い電気電導度を有する液体を少なくとも該室の容積量を通水した後に通水を止める事を特徴とする脱イオン水を製造する運転方法。
（２）前記の液体が、前記被処理水または前記脱イオン水であることを特徴とする（１）に記載の運転方法。
（３）前記の液体が、前記脱イオン水であることを特徴とする（１）記載の運転方法。
（４）脱塩室への通水を、印加電圧の停止と同時に停止することを特徴とする（１）〜（３）のいずれかに記載の運転方法。
（５）前記の液体の通水量が、濃縮室の容積量以上で濃縮室容積量の１０倍未満であることを特徴とする（１）〜（４）のいずれかに記載の運転方法。
【０００６】
【発明の実施の形態】
本発明について以下具体的に説明する。
本発明は、陽極を備える陽極室と、陰極を備える陰極室との間にカチオン交換膜とアニオン交換膜を交互に配置させ、陽極側がアニオン交換膜で区画され陰極側がカチオン交換膜で区画された脱塩室と陽極側がカチオン交換膜で区画され陰極側がアニオン交換膜で区画された濃縮室が交互に形成された電気透析装置の少なくとも脱塩室にイオン交換体を充填した電気式脱イオン水製造装置を使用する。
【０００７】
脱塩室には、被処理水を流入させ、濃縮室には被処理水又は被処理水の一部を循環しても構わない。又、必要に応じて脱塩室以外の濃縮室や電極室に、イオン交換体を充填しても構わない。この様な電気脱イオン水製造装置で、直流電圧を両電極間に印加すると、脱塩室では、被処理水中の不純物イオンは、一旦脱塩室に充填されたイオン交換体により吸着除去され、次に電気的推進力によりイオン交換体から脱離されイオン交換膜を透過して、濃縮室に移動し、排出される。一方、不純物イオンが除去された脱イオン水は、脱塩室より流出する。
【０００８】
次に、本発明の運転方法は、運転停止法として、まず陽極陰極間の印加電圧を停止させ、その後、印加電圧を停止した時に前記濃縮室にある濃縮液の電気電導度より低い電気電導度を有する液体を少なくとも該室の容積量を通水した後に通水を停止する事を特徴とする。濃縮室に通水する濃縮液の電気電導度より低い電気電導度を有する液体を通水する事で、濃縮室と脱塩室との濃度差により濃縮液から隔膜であるイオン交換膜を介して脱塩室側にＮａＣｌ等の塩分が移動する事が少なくなり、脱塩室の液体の電気伝導度を低く保ち、汚染を防ぐ事が出来る。それにより、運転再開時の安定までの時間を短くする事が出来る。
【０００９】
濃縮室に通水する濃縮液の電気電導度より低い電気電導度を有する液体としては、被処理水や脱塩室より流出した脱イオン水が好ましい。特に、脱塩室からの脱イオン水を濃縮室に通水する事は、濃縮室と脱塩室の液組成が同じとなり、電気電導度の上昇が抑えられ、より好ましい。
又、濃縮室の容積量とは、充填されているイオン交換体の容積を除いた、液体が通水される部分の容積である。脱塩室への通水は、印加電圧の停止と同時に停止する事が、脱塩室に被処理水が流入する事を防ぎ、脱塩室の電気伝導度を低く保ち、更に、該室の充填イオン交換体の汚染も防ぐ為にも好ましい。
濃縮室に通水する濃縮液の電気電導度より低い液体の通水量は、少なくとも該室の容積量以上である。通水量が該室の容積量未満では、液の置換が不十分である。通水量が、該室の容積量の１０倍未満である事が好ましい。通水が、該室の容積量の１０倍以上では、停止に時間がかかり、コスト的に不利である。より好ましくは、通水量が、該室の容積量の２倍以上、５倍未満である。
本発明における電気脱イオン水製造装置の形式は、スタック形式の積層型やスパイラル型等、特に限定されない。
【００１０】
脱塩室に充填されるイオン交換体としては、繊維状、粒状、シート状があるが、この中で単独又は組み合わせて使用する事ができ又、その大きさについても特に限定されるものではない。好ましいイオン交換体としては、イオン交換樹脂があげられる。又、交換体の構造では、強酸性や弱酸性のカチオン交換体及び強塩基性や弱塩基性のアニオン交換体の中から適宜選択出来る。又、カチオン交換体とアニオン交換体の比率も被処理水の水質に合わせて適宜選択出来る。
【００１１】
カチオン交換膜は、特に限定されず、補強材で補強された均一膜や交換樹脂と他のポリマーがブレンドされた不均一膜が使用出来る。構造としては、スチレンとジビニルベンゼン共重合体のスルホン化物やポリスチレンスルホン酸及びその塩、ポリビニルスルホン酸及びその塩、ポリアクリル酸及びその塩、ポリメタクリル酸及びその塩等を含有する膜が挙げられる。
【００１２】
アニオン交換膜も、特に限定されず、補強材で補強された均一膜や交換樹脂と他のポリマーがブレンドされた不均一膜が使用出来る。構造としては、スチレンとジビニルベンゼン共重合体のクロロメチル化反応後の４級アミノ化物、クロロメチルスチレンとジビニルベンゼン共重合体の４級アミノ化物、４−ビニルピリジンとジビニルベンゼン共重合体の４級アミノ化物及びその４級ピリジニウム化物、２−ビニルピリジンとジビニルベンゼン共重合体及びその４級ピリジニウム化物、１−ビニルイミダゾールとジビニルベンゼン共重合体及びその４級化物、Ｎ，Ｎ−ジメチルアクリルアミドとジビニルベンゼン重合体及びその４級化物、Ｎ，Ｎ−ジメチルアミノプロピルアクリルアミドとジビニルベンゼン重合体及びその４級化物等を含有する膜が挙げられる。
【００１３】
又、濃縮室は、特にスケール成分である、Ｃａ塩には十分配慮する必要があり、電気透析で行われているＰＨ調整やスケール防止剤での調整は、好ましい方法である。ＰＨ調整は、外部添加でも電極液による内部添加でもどちらでも構わない。
次に実施例によって本発明を説明するが、これに限定されるものでない。
【００１４】
【実施例１】
脱塩室４室、濃縮室４室、室厚み各々３ｍｍからなる電気透析装置の脱塩室に、イオン交換体として再生形の強酸性カチオン交換樹脂と再生形の強塩基性アニオン交換樹脂を均一混合状態で充填した電気脱イオン水製造装置を用いた。この時の、脱塩室でのイオン交換体の容積充填率は８０％であった。又、カチオン交換膜とアニオン交換膜は、各々アシプレックス（商品名、旭化成（株）製）Ｋ−５０１とＡ−５０１を使用した。
【００１５】
電導度２００μｓ／ｃｍの被処理水を脱塩室に、イオン交換体の容積に対し、１時間当たり２７倍の流量を流し、濃縮室に、被処理水を脱塩室流量に対し、１／５の流量を流した。電流密度は、３０Ａ／ｍ2で約１０時間通電を行った。
得られた、脱イオン水の電気電導度は、５０μｓ／ｃｍで、安定した水質が得られた。次に、運転停止の手順は、まず、印加電圧と脱塩室への通水を同時に停止した後、濃縮室へは、濃縮室の容積量を通水した後に通水を停止した。２４ｈｒ停止した後に運転を再開した。脱イオン水の電導度が５０μｓ／ｃｍに達し、安定するまでの時間は、１５分であった。
【００１６】
【比較例１】
実施例１と同じ電気脱イオン水製造装置、被処理水及び運転条件にて運転し、得られた、脱イオン水の電気電導度は、５０μｓ／ｃｍで、安定した水質が得られた。次に、運転停止は、印加電圧、脱塩室及び濃縮室への通水を同時に停止した。２４ｈｒ停止した後に運転を再開した。脱イオン水の電気電導度が５０μｓ／ｃｍに達し、安定するまでの時間は、約６０分であった。
【００１７】
【発明の効果】
本発明の方法は、頻繁に運転と停止を繰り返す運転形態でも、安定な水質の脱イオンを早く供給でき、且つ低コストにて製造する効果を有する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an operation method for efficiently producing pure water and deionized water used in a semiconductor manufacturing field, a power plant field, a boiler field, a pharmaceutical field, a research facility, and the like with an electric deionized water manufacturing apparatus.
[0002]
[Prior art]
In recent years, as a method for producing deionized water, an electric deionization method in which the drawbacks of conventional ion exchange resins are improved has been developed and put into practical use. This method is an electrodialysis apparatus in which a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode chamber having an anode and a cathode chamber having an anode, and a desalting chamber and a concentration chamber are alternately formed between the two membranes. The desalting chamber is filled with ion exchange resin, and while applying voltage, the water to be treated flows into the desalting chamber, and the water to be treated or a part of the concentrated water flows into the concentrating chamber as concentrated water. This is to deionize the desalination chamber. In this method, since the ion exchanger is continuously regenerated, it is not necessary to regenerate with a chemical such as acid or alkali.
[0003]
However, when the operation is stopped, salt such as NaCl moves to the desalting chamber side from the concentrated solution through the ion exchange membrane as a diaphragm due to the concentration difference between the concentrating chamber and the desalting chamber. For this reason, the ion exchanger filled in the desalting chamber is maintained in the regeneration type during operation, but becomes a load type and is contaminated. Therefore, at the start of operation, until the ion exchanger in the demineralization chamber changes to the regenerative type, the water quality and conductivity of the deionized water are not stable, and the water and electricity bills during that time are lost. In this way, at the start of operation, it takes time to start up to a stable operation, resulting in a decrease in water utilization rate and an increase in operation cost of electricity bill.
[0004]
[Problems to be solved by the invention]
The present invention proposes an operation method in which a decrease in water utilization rate at the start of operation and an efficiency decrease in operation cost UP for electricity bills are improved.
[0005]
[Means for Solving the Problems]
As a result of various studies on the method of minimizing the loss of water utilization rate at the start of operation and the loss of the operating cost UP of electricity bill, the present inventors have devised a stop method at the time of operation stop. The inventors have found that the object has been achieved and have completed the present invention.
That is, the present invention is as follows.
(1) At least a desalting chamber of an electrodialysis apparatus in which a cation exchange membrane and an anion exchange membrane are alternately arranged between the anode chamber and the cathode chamber, and a desalting chamber and a concentration chamber are alternately formed between the two membranes. In an operation method for producing deionized water by flowing water to be treated into an electric deionized water production apparatus filled with an ion exchanger, after stopping the applied voltage between the anode and cathode after producing deionized water, driving how to produce deionized water, characterized in that the stop water flow after passed through the volume of at least said chamber a liquid having a low electrical conductivity than the electrical conductivity of the concentrate to the concentrate compartment.
(2) The operation method according to (1), wherein the liquid is the treated water or the deionized water.
(3) The operation method according to (1), wherein the liquid is the deionized water.
(4) The operation method according to any one of (1) to (3), wherein water flow to the desalting chamber is stopped simultaneously with the stop of the applied voltage.
(5) The operation method according to any one of (1) to (4), wherein the water flow rate of the liquid is greater than or equal to the volume of the concentration chamber and less than 10 times the volume of the concentration chamber.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be specifically described below.
In the present invention, a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode chamber having an anode and a cathode chamber having a cathode, and the anode side is partitioned by an anion exchange membrane and the cathode side is partitioned by a cation exchange membrane. Electric deionized water production in which at least a desalting chamber of an electrodialysis apparatus in which a desalting chamber and an anode side are partitioned by a cation exchange membrane and a concentration chamber in which a cathode side is partitioned by an anion exchange membrane is alternately formed is filled with an ion exchanger Use equipment.
[0007]
To-be-treated water may be allowed to flow into the desalting chamber, and the to-be-treated water or a part of the to-be-treated water may be circulated into the concentration chamber. Further, if necessary, an ion exchanger may be filled in a concentration chamber or an electrode chamber other than the desalting chamber. In such an electrodeionized water production apparatus, when a DC voltage is applied between both electrodes, in the desalting chamber, impurity ions in the water to be treated are adsorbed and removed by the ion exchanger once filled in the desalting chamber, Next, it is desorbed from the ion exchanger by the electric driving force, permeates through the ion exchange membrane, moves to the concentration chamber, and is discharged. On the other hand, the deionized water from which the impurity ions have been removed flows out from the demineralization chamber.
[0008]
Next, in the operation method of the present invention, as the operation stop method, first, the applied voltage between the anode and the cathode is stopped, and then the electric conductivity lower than the electric conductivity of the concentrate in the concentrating chamber when the applied voltage is stopped. The water flow is stopped after passing at least the volume of the liquid having the above. By passing a liquid having an electric conductivity lower than the electric conductivity of the concentrated liquid flowing through the concentrating chamber, the concentration difference between the concentrating chamber and the desalting chamber causes a difference from the concentrated liquid through the ion exchange membrane. It is less likely that salt such as NaCl moves to the desalting chamber side, and the electrical conductivity of the liquid in the desalting chamber can be kept low to prevent contamination. As a result, the time until stabilization at the time of restarting operation can be shortened.
[0009]
As the liquid having an electric conductivity lower than the electric conductivity of the concentrated liquid passing through the concentration chamber, water to be treated and deionized water flowing out from the demineralization chamber are preferable. In particular, it is more preferable to pass deionized water from the desalting chamber to the concentrating chamber because the liquid compositions of the concentrating chamber and the desalting chamber are the same, and an increase in electrical conductivity is suppressed.
The volume of the concentrating chamber is the volume of the portion through which the liquid is passed, excluding the volume of the ion exchanger filled. Stopping the flow of water to the desalting chamber at the same time as the applied voltage is stopped prevents the treated water from flowing into the desalting chamber, keeps the electrical conductivity of the desalting chamber low, It is also preferable for preventing contamination of the packed ion exchanger.
The amount of water that is lower than the electrical conductivity of the concentrated liquid that passes through the concentration chamber is at least equal to or greater than the volume of the chamber. If the amount of water flow is less than the volume of the chamber, the replacement of the liquid is insufficient. It is preferable that the water flow rate is less than 10 times the volume of the chamber. If the water flow is more than 10 times the volume of the chamber, it takes time to stop, which is disadvantageous in terms of cost. More preferably, the water flow rate is not less than 2 times and less than 5 times the volume of the chamber.
The type of the electrodeionized water production apparatus in the present invention is not particularly limited, such as a stack type stacked type or a spiral type.
[0010]
The ion exchanger filled in the desalting chamber may be in the form of fibers, granules, or sheets, but can be used alone or in combination, and the size is not particularly limited. . A preferred ion exchanger is an ion exchange resin. In addition, the structure of the exchanger can be appropriately selected from strong acidic and weak acidic cation exchangers and strong basic and weak basic anion exchangers. Further, the ratio of the cation exchanger to the anion exchanger can be appropriately selected according to the quality of the water to be treated.
[0011]
The cation exchange membrane is not particularly limited, and a uniform membrane reinforced with a reinforcing material or a heterogeneous membrane in which an exchange resin and other polymers are blended can be used. Examples of the structure include a sulfonated product of styrene and divinylbenzene copolymer, polystyrene sulfonic acid and its salt, polyvinyl sulfonic acid and its salt, polyacrylic acid and its salt, polymethacrylic acid and its salt, and the like. .
[0012]
The anion exchange membrane is not particularly limited, and a uniform membrane reinforced with a reinforcing material or a non-uniform membrane in which an exchange resin and other polymers are blended can be used. As the structure, quaternary amination product after chloromethylation reaction of styrene and divinylbenzene copolymer, quaternary amination product of chloromethylstyrene and divinylbenzene copolymer, 4-vinylpyridine and divinylbenzene copolymer 4 Quaternary amination and its quaternary pyridinium, 2-vinylpyridine and divinylbenzene copolymer and its quaternary pyridinium, 1-vinylimidazole and divinylbenzene copolymer and its quaternization, N, N-dimethylacrylamide and Examples include a film containing a divinylbenzene polymer and a quaternized product thereof, N, N-dimethylaminopropylacrylamide, a divinylbenzene polymer and a quaternized product thereof, and the like.
[0013]
In addition, in the concentration chamber, it is necessary to pay sufficient attention to Ca salt, which is a scale component, and pH adjustment and adjustment with a scale inhibitor, which are performed by electrodialysis, are preferable methods. PH adjustment may be either external addition or internal addition using an electrode solution.
Next, the present invention will be described by way of examples, but the present invention is not limited to these examples.
[0014]
[Example 1]
Regenerative strongly acidic cation exchange resin and regenerated strongly basic anion exchange resin are uniformly used as ion exchangers in the desalination chamber of the electrodialysis machine, which consists of 4 desalination chambers, 4 concentrating chambers, and a chamber thickness of 3 mm each. An electrodeionized water production apparatus filled in a mixed state was used. At this time, the volume filling rate of the ion exchanger in the desalting chamber was 80%. As the cation exchange membrane and the anion exchange membrane, Aciplex (trade name, manufactured by Asahi Kasei Co., Ltd.) K-501 and A-501 were used.
[0015]
The water to be treated having an electric conductivity of 200 μs / cm is supplied to the desalting chamber at a flow rate of 27 times per hour with respect to the volume of the ion exchanger, and the water to be treated is 1 / A flow rate of 5 was applied. The current density was 30 A / m 2 and energization was performed for about 10 hours.
The obtained deionized water had an electric conductivity of 50 μs / cm, and a stable water quality was obtained. Next, in order to stop the operation, first, the applied voltage and water flow to the desalting chamber were stopped simultaneously, and then the water flow was stopped after passing the volume of the concentration chamber to the concentration chamber. The operation was resumed after stopping for 24 hours. The time until the conductivity of deionized water reached 50 μs / cm and stabilized was 15 minutes.
[0016]
[Comparative Example 1]
The electric conductivity of the deionized water obtained by operating with the same electrodeionized water production apparatus, treated water and operating conditions as in Example 1 was 50 μs / cm, and a stable water quality was obtained. Next, in the operation stop, the applied voltage, the water flow to the desalination chamber and the concentration chamber were stopped simultaneously. The operation was resumed after stopping for 24 hours. The time until the electric conductivity of deionized water reached 50 μs / cm and stabilized was about 60 minutes.
[0017]
【The invention's effect】
The method of the present invention has an effect of being able to supply stable deionized water quality quickly and at low cost even in an operation mode in which operation and stop are frequently repeated.
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