JP2004041054A

JP2004041054A - Method for purifying sugar solution

Info

Publication number: JP2004041054A
Application number: JP2002201528A
Authority: JP
Inventors: Seisho Konuki; 小貫　政将; Ichiro Kurihara; 栗原　一郎; Yoshiichi Nakagawa; 中川　芳一
Original assignee: Nippon Rensui Co
Current assignee: Nippon Rensui Co
Priority date: 2002-07-10
Filing date: 2002-07-10
Publication date: 2004-02-12
Anticipated expiration: 2022-07-10
Also published as: JP4193432B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a profitable method for purifying a sugar solution, which adopts a technique different from a countercurrent recycling technique, does not cause the problem of impurity leakage before the breakthrough of a resin, and can prevent the proliferation of bacteria. <P>SOLUTION: This method for purifying the sugar solution is characterized by comprising a purifying process for passing the sugar solution as a raw material through a solution-passing tower having a strongly acidic cation exchange resin (C) layer and a weakly basic anion exchange resin (A) layer sequentially formed from the upper side therein from the overhead portion, a C-recycling process for transporting the C layer in the solution-passing tower to a recycling tower, after the solution is passed through the purifying process, supplying an acid-recycling agent from the overhead portion and stopping the supply of the acid-recycling agent, before a resin in the recycling tower is perfectly recycled, an A-recycling process for supplying an alkali-recycling agent to the solution-passing tower having the empty portion in the upper portion from the overhead portion in the form of contacting with the inner wall surface of the empty portion, and a purification-preparing process for supplying the recycled resin (C) to the upper portion of the solution-passing tower to reform the C layer on the A layer, when the resin (A) is recycled, wherein two or more C layers having different recycling rates are formed in the recycling tower, and the C layers are sequentially supplied to the upper portion of the solution-passing tower from the upper layer fraction having a high recycling rate. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、糖液の精製方法に関し、詳しくは、イオン交換樹脂を使用し、その再生工程を改良した糖液の精製方法に関する。
【０００２】
【従来の技術】
従来より、脱塩・脱色を目的とした糖液の精製方法としてはイオン交換樹脂を使用した各種の方法が知られている。例えば、デンプン糖液の場合には、強酸性カチオン交換樹脂塔、弱塩基性アニオン交換樹脂塔、強酸性カチオン交換樹脂および強塩基性アニオン交換樹脂の混合樹脂塔を備えた精製工程に原料糖液を順次に通液する方法が知られている。斯かる方法においては、通液終了後の再生工程は、各樹脂塔毎にそれぞれ必要な再生剤を供給することによって行なわれる。なお、混合樹脂塔の場合は、塔の下部から洗浄水を供給して樹脂を流動させた後に樹脂の比重差によって樹脂毎の分離層を形成する逆洗分離工程が採用され、その後に再生工程に付される。
【０００３】
上記の強酸性カチオン交換樹脂塔の再生工程において、塔内の樹脂が完全に再生されるまで再生剤を供給した場合は再生剤の使用量が膨大となり極めて不経済である。そのため、完全再生に必要な量の再生剤が供給されることはなく、従って、次の精製工程において樹脂破過前に樹脂から不純物が定常的にリークするという不可避的問題が生じる。斯かる問題は、流体の流し方が精製工程および再生工程とも下向流である並流再生の場合に起こり、精製工程が下向流で再生工程が上向流である向流再生によって防止することが出来る。
【０００４】
しかしながら、向流再生を適用した場合は、再生時の樹脂層の流動化を防止するため、樹脂層上部から下向流で押さえ水を供給する必要があり、水の使用量が増加するという問題がある。更に、再生剤の濃度を高くした場合、樹脂層が流動化して効率良く再生が行われないことから、再生剤の濃度を低くする必要があり、そのため、再生剤の濃度調節のための希釈水の使用量が増加するという問題もある。
【０００５】
ところで、精製工程においては、一般に、菌の増殖に好適な条件とされている３０〜４０℃の温度でデンプン糖液が供給されるため、特に第１塔の強酸性カチオン交換樹脂塔内（主として糖液が滞留し易い塔の内壁面）において菌が増殖する。そして、菌による糖の分解に伴い、有機酸類、炭酸類などの弱酸類が新たに生成され、第２塔の弱塩基性アニオン交換樹脂塔の負荷増大を惹起し、処理液量および処理液質が低下するという懸念がある。
【０００６】
また、糖液の精製においては、切替運転により精製工程の操作を連続化する要請が高い。ところが、切替運転には多数の塔が必要となり（前記の従来例では少なくとも６塔必要）、少しでも塔数を減らして建設費や運転費を軽減することが望まれる。
【０００７】
【発明が解決しようとする課題】
本発明は、上記実情に鑑みなされたものであり、その目的は、向流再生とは異なる技術を採用し、樹脂破過前の不純物のリークの問題がなく且つ菌の繁殖を防止することが出来、しかも、切替運転を行なわんとした場合には少ない塔数で済むことが出来る、工業的に有利な糖液の精製方法を提供することにある。
【０００８】
【課題を解決するための手段】
すなわち、本発明の要旨は、上部から順次に強酸性カチオン交換樹脂層と弱塩基性アニオン交換樹脂層とが形成された通液塔に塔上部から原料糖液を通液する精製工程と、精製工程の通液終了後、通液塔の強酸性カチオン交換樹脂層を再生塔に移送し、塔上部から酸再生剤を供給し且つ再生塔内の樹脂が完全に再生される前に酸再生剤の供給を停止する強酸性カチオン交換樹脂の再生工程と、上部が空塔になされた通液塔に塔上部から壁面に接触する態様でアルカリ再生剤を供給する弱塩基性アニオン交換樹脂の再生工程と、弱塩基性アニオン交換樹脂の再生終了後、通液塔の上部に再生済みの強酸性カチオン交換樹脂を供給して弱塩基性アニオン交換樹脂層の上部に強酸性カチオン交換樹脂層を再形成し、その際、再生塔内において上下方向の再生率の異なる２層以上に強酸性カチオン交換樹脂層を区分し、再生率の高い上部の区分から順次に通液塔の上部に供給する精製準備工程とを包含することを特徴とする糖液の精製方法に存する。
【０００９】
そして、本発明の好ましい態様においては、３塔以上の通液塔（Ｎ１，Ｎ２，Ｎ３・・・）と１塔の再生塔を備え、２塔の通液塔（Ｎ１，Ｎ２）を直列に使用して精製工程に付し、精製工程の通液終了後、下流側の通液塔（Ｎ２）と通液塔（Ｎ３）を直列に使用して精製工程に付し、上流側の通液塔（Ｎ１）を再生工程と精製準備工程に付し、精製工程の通液終了後、２塔の通液塔（Ｎ３，Ｎ１）を直列に使用して精製工程に付し、上流側の通液塔（Ｎ２）を再生工程と精製準備工程に付し、順次に上記の操作を繰り返す。
【００１０】
【発明の実施の形態】
以下、本発明を添付図面に基づいて詳細に説明する。図１〜５は本発明の好ましい態様の一例を示す説明図である。
【００１１】
本発明が適用される原料糖液について説明する。本発明は、脱塩や脱色が必要とされる全ての糖液に適用される。斯かる糖液としては、ぶとう糖液、異性化糖液（ぶどう糖＋果糖）、水飴などの澱粉糖液、ソルビトール、マルチトール等の糖アルコール、乳糖含有糖液、蔗糖液の他、各種のオリゴ糖液が挙げられる。
【００１２】
本発明ではイオン交換樹脂として強酸性カチオン交換樹脂と弱塩基性アニオン交換樹脂を使用する。強酸性カチオン交換樹脂としては、例えば、ダイヤイオン（登録商標、以下同じ）ＳＫ１Ｂ、ＳＫ１１０、ＰＫ２１６、ＰＫ２１２等、アンバーライト（登録商標、以下同じ）２００ＣＴ、ＩＲ１２０Ｂ、ＩＲ１２４、ＩＲ１１８等が挙げられ、弱塩基性アニオン交換樹脂としては、例えば、ダイヤイオンＷＡ１０、ＷＡ２０、ＷＡ２１、ＷＡ３０等、アンバーライトＸＥ５８３、ＩＲＡ６７、ＩＲＡ９６ＳＢ等が挙げられる。
【００１３】
そして、強酸性カチオン交換樹脂は、酸再生剤（ＨＣｌ等）で再生処理されてＨ型として使用され、弱塩基性アニオン交換樹脂は、アルカリ再生剤（ＮａＯＨ等）で再生処理されてＯＨ型として精製工程に付される。そして、これらのイオン交換樹脂により脱塩が行われ、同時に脱色も行なわれる。
【００１４】
本発明においては、上記の様に、酸再生剤としては塩酸水溶液、アルカリ再生剤としては水酸化ナトリウム水溶液が好適に使用される。通常、塩酸水溶液の濃度は２〜１０重量％、水酸化ナトリウム水溶液の濃度は２〜５重量％である。
【００１５】
本発明に係る糖液の精製方法は、精製工程と、強酸性カチオン交換樹脂の再生工程（Ｉ）と、弱塩基性アニオン交換樹脂の再生工程（ＩＩ）と、精製準備工程とを包含する。糖液の通液塔は、上部から順次に強酸性カチオン交換樹脂層（Ｃ）と弱塩基性アニオン交換樹脂層（Ａ）とが形成されて構成される。なお、弱塩基性アニオン交換樹脂層（Ａ）の上に強酸性カチオン交換樹脂層（Ｃ）を直接に積層してもよく、弱塩基性アニオン交換樹脂層（Ａ）の上に液体は通過させるが樹脂は通過させない支持機構を設置し、その上に強酸性カチオン交換樹脂層（Ｃ）を積層してもよい。
【００１６】
図示した例は、切替運転により精製工程の操作を連続化するため、３塔の通液塔（Ｎ１，Ｎ２，Ｎ３）と１塔の再生塔を備えている。そして、２塔の通液塔（Ｎ１）と（Ｎ２）を直列に使用して精製工程に付している。斯かる２塔通液方式によれば精製程度が高められる効果がある。通常、１つの通液塔において、強酸性カチオン交換樹脂と弱塩基性アニオン交換樹脂とは、通常１：０．６〜１．０（容積比）で充填される。
【００１７】
（１）精製工程として、上部から順次に強酸性カチオン交換樹脂層（Ｃ）と弱塩基性アニオン交換樹脂層（Ａ）とが形成された通液塔（Ｎ１）に塔上部から原料糖液（Ｆ）を通液する。そして、通液塔（Ｎ２）の塔下部から精製糖液（Ｐ）を回収する。精製工程の条件は特に制限されないが、通常、液温度は３０〜５０℃、液流速（空間速度）は通液塔１塔当たりの弱塩基性アニオン交換樹脂層（Ａ）に対し２〜１０Ｈｒ^−１である。２塔の通液塔（Ｎ１）と（Ｎ２）による精製工程の通液終了時点は、例えば、上流側の通液塔（Ｎ１）における樹脂の破過現象（不純物のリーク）によって判断することが出来る。斯かる不純物のリークの判断は通液塔（Ｎ１）の出口側の液質（電気伝導率、吸光度、ｐＨ等）の測定によって行なうことが出来る。
【００１８】
（２）切替運転として、上記の精製工程の通液終了後、下流側の通液塔（Ｎ２）と通液塔（Ｎ３）を直列に使用して精製工程に付す。その結果、精製工程の操作が連続化される。精製工程の条件は前記と同一である。また、通液終了時点の判断も前記と同一に行なわれる。
【００１９】
（３）一方、前記の通液塔（Ｎ１）と（Ｎ２）とによる精製工程の通液終了後、上流側の通液塔（Ｎ１）を再生工程と精製準備工程に付す。すなわち、強酸性カチオン交換樹脂の再生工程（Ｉ）と、弱塩基性アニオン交換樹脂の再生工程（ＩＩ）と、精製準備工程とを行なう。
【００２０】
（３ａ）先ず、強酸性カチオン交換樹脂の再生工程（Ｉ）として、通液塔（Ｎ１）の強酸性カチオン交換樹脂層（Ｃ）を再生塔（Ｒ）に移送し、塔上部から酸再生剤（ＨＣｌ）を供給し且つ再生塔（Ｒ）内の樹脂が完全に再生される前に酸再生剤の供給を停止する。樹脂の移送は、例えば、強酸性カチオン交換樹脂層（Ｃ）と弱塩基性アニオン交換樹脂層（Ａ）との界面付近に設置された樹脂抜出管によって行なうことが出来る。酸再生剤（ＨＣｌ）の供給量は、再生剤の濃度に依存し、７重量％ＨＣｌの場合、通常、樹脂量に対して０．５〜２．０容量倍である。その結果、再生塔（Ｒ）内の樹脂の全量は再生されず、模式的に示した様に、再生塔（Ｒ）の下方に行くに従って再生率が低下する。その他の条件は特に制限されないが、通常、液温度は１０〜４０℃、液流速（空間速度）は０．５〜５．０Ｈｒ^−１である。
【００２１】
（３ｂ）次に、弱塩基性アニオン交換樹脂の再生工程（ＩＩ）として、上部が空塔になされた通液塔（Ｎ１）に塔上部から壁面に接触する態様でアルカリ再生剤（ＮａＯＨ）を供給する。壁面に接触する態様としては、壁面を流下させる方法、空塔部にアルカリ再生剤を充満させる方法などがある。後者の方法の場合、空塔部に水を充満させた後にアルカリを添加して溶解させてもよい。
【００２２】
上記の操作により、通液塔の内壁面で繁殖すると考えられる菌の殺菌が行われ、内壁面がアルカリ状態となるために次の精製工程における通液の際の菌の繁殖が抑制される。弱塩基性アニオン交換樹脂の再生工程の条件は特に制限されないが、４重量％ＮａＯＨの場合、その供給量は、通常、樹脂量に対して１．０〜３．０容量倍、液温度は１０〜４０℃、液流速（空間速度）は０．５〜５．０Ｈｒ^−１である。
【００２３】
（３ｃ）そして、精製準備工程として、弱塩基性アニオン交換樹脂の再生終了後、通液塔（Ｎ１）の上部に再生済みの強酸性カチオン交換樹脂を供給して弱塩基性アニオン交換樹脂層（Ａ）の上部に強酸性カチオン交換樹脂層（Ｃ）を再形成する。その際、再生塔（Ｒ）内において上下方向の再生率の異なる２層以上に強酸性カチオン交換樹脂層を区分し、再生率の高い上部の区分から順次に通液塔（Ｎ１）の上部に供給する。図示した例においては、再生塔（Ｒ）内の強酸性カチオン交換樹脂層は３層に区分されている。なお、各層においては再生率の分布が存在するため、通液塔（Ｎ１）の上部に供給する際に混合するのが好ましい。斯かる精製準備工程によれば、向流再生を行なわずに樹脂破過前の不純物のリークを防止することが出来る。
【００２４】
（４）切替運転として、前記の２塔の通液塔（Ｎ２）と（Ｎ３）による精製工程の通液終了後、下流側の通液塔（Ｎ３）と通液塔（Ｎ１）を直列に使用して精製工程に付す。
【００２５】
（５）一方、上記の通液塔（Ｎ２）と（Ｎ３）による精製工程の通液終了後、通液塔（Ｎ２）を再生工程と精製準備工程に付す。
【００２６】
（６）順次に上記の操作（１）〜（５）を繰り返す。なお、説明を省略したが、通常、精製工程から再生工程に切替える通液塔においは塔内の残存糖液を回収するための水洗処理が常套手段として設けられ、また、上記の各再生工程においては再生剤の供給の終了後に再生剤を押出すための水洗処理が常套手段として設けられる。
【００２７】
【実施例】
以下、本発明を実施例により更に詳細に説明するが、本発明は、その要旨を超えない限り、以下の実施例に限定されるものではない。
【００２８】
以下の実施例においては、図１〜５に示す方法に従った切替運転により精製工程の操作を連続して行なった。ただし、精製工程終了後に通液塔内に残存する糖液を回収するための水洗処理、および、再生剤の供給の終了後に再生剤を押出すための水洗処理の記載は省略した。３塔の通液塔（Ｎ１，Ｎ２，Ｎ３）と１塔の再生塔は次の構成とした。
【００２９】
＜通液塔＞
内径２０ｍｍ、高さ１ｍの塔に上部から順次に強酸性カチオン交換樹脂（三菱化学社製の「ＳＫ１Ｂ」）９０ｍｌと弱塩基性アニオン交換樹脂（三菱化学社製の「ＷＡ３０」）１００ｍｌを充填し、上部に液導入管、下部に液排出管を備え、強酸性カチオン交換樹脂層と弱塩基性アニオン交換樹脂層との界面付近に樹脂抜出管が設置された通液塔を使用した。そして、３塔の通液塔（Ｎ１，Ｎ２，Ｎ３）は相互に切替運転可能に配管接続した。
【００３０】
＜再生塔＞
内径２０ｍｍ、高さ０．５ｍの塔の上部に液導入管、下部に液排出管を備え、下部から樹脂の充填高さ相当位置までの間を約３等分する各位置には２本の中間抜出管（上側中間抜出管と下側中間抜出管）が設置され、塔下部には塔下部抜出管が設置された再生塔を使用した。
【００３１】
実施例１
次の操作（１）〜（５）を繰り返し、活性炭処理で粗脱色されたブドウ糖液（糖濃度３０重量％）の連続精製を行なった。
【００３２】
（１）通液塔（Ｎ１）に塔上部から原料糖液（Ｆ）を通液した。そして、通液塔（Ｎ２）の塔下部から精製糖液（Ｐ）を回収した。液温度は４０℃、液流速（空間速度）は各通液糖の弱塩基性アニオン交換樹脂に対して５Ｈｒ^−１である。通液塔（Ｎ１）における樹脂の破過現象（不純物のリーク）を確認し、２塔の通液塔（Ｎ１）と（Ｎ２）による精製工程の通液を終了した。
【００３３】
（２）上記の通液終了後、通液塔（Ｎ２）と通液塔（Ｎ３）を直列に使用した精製工程に切替えた。
【００３４】
（３）一方、前記の通液塔（Ｎ１）と（Ｎ２）とによる精製工程の通液終了後、通液塔（Ｎ１）を再生工程と精製準備工程に付す。すなわち、強酸性カチオン交換樹脂の再生工程（Ｉ）と、弱塩基性アニオン交換樹脂の再生工程（ＩＩ）と、精製準備工程とを行なった。
【００３５】
（３ａ）先ず、強酸性カチオン交換樹脂の再生工程（Ｉ）として、通液塔（Ｎ１）の強酸性カチオン交換樹脂層（Ｃ）を再生塔（Ｒ）に移送した。樹脂の移送は、強酸性カチオン交換樹脂層（Ｃ）と弱塩基性アニオン交換樹脂層（Ａ）との界面付近に設置された樹脂抜出管によって行なった。そして、再生塔（Ｒ）の塔上部から酸再生剤（７重量％塩酸水溶液）を供給した。酸再生剤の供給量は樹脂量に対して１容量倍、液温度は常温、液流速（空間速度）は２Ｈｒ^−１である。
【００３６】
（３ｂ）次に、弱塩基性アニオン交換樹脂の再生工程（ＩＩ）として、上部が空塔になされた通液塔（Ｎ１）に塔上部から壁面を流下させてアルカリ再生剤（４重量％水酸化ナトリウム水溶液）を供給する。アルカリ再生剤の供給量は樹脂量に対して１．５容量倍、液温度は常温、液流速（空間速度）は２Ｈｒ^−１である。
【００３７】
（３ｃ）そして、精製準備工程として、弱塩基性アニオン交換樹脂の再生終了後、通液塔（Ｎ１）の上部に再生済みの強酸性カチオン交換樹脂を供給して弱塩基性アニオン交換樹脂層（Ａ）の上部に強酸性カチオン交換樹脂層（Ｃ）を再形成した。その際、再生塔（Ｒ）内の強酸性カチオン交換樹脂層を３層に区分し、再生塔（Ｒ）の上側中間抜出管、下側中間抜出管および塔下部抜出管により、上層側から順次に通液塔（Ｎ１）の上部に供給した。
【００３８】
（４）前記の通液塔（Ｎ２）と（Ｎ３）による精製工程の通液終了後、通液塔（Ｎ３）と通液塔（Ｎ１）を直列に使用した精製工程に切替えた。
【００３９】
（５）一方、上記の通液塔（Ｎ２）と（Ｎ３）による精製工程の通液終了後、通液塔（Ｎ２）を再生工程と精製準備工程に付した。そして、順次に上記の操作（１）〜（５）を３回繰り返した。表１に精製糖液の液質を示す。表１から明らかな様に液質は極めて高純度である。また、操作を繰り返すことによる処理能力の低下は認められなかった。なお、表中の着色度は、１００ｍｍセルを使用し、４２０ｎｍの波長で測定した吸光度の値である。
【００４０】
【表１】

【００４１】
【発明の効果】
以上説明した本発明によれば、向流再生とは異なる技術を採用し、樹脂破過前の不純物のリークの問題がなく且つ菌の繁殖を防止することが出来、しかも、切替運転を行なわんとした場合には少ない塔数で済むことが出来る、工業的に有利な糖液の精製方法が提供される。
【図面の簡単な説明】
【図１】本発明の好ましい態様の一例を示す説明図（精製工程）
【図２】本発明の好ましい態様の一例を示す説明図（再生工程（Ｉ））
【図３】本発明の好ましい態様の一例を示す説明図（再生工程（ＩＩ））
【図４】本発明の好ましい態様の一例を示す説明図（精製準備工程）
【図５】本発明の好ましい態様の一例を示す説明図（精製工程）
【符号の説明】
Ｎ１：通液塔
Ｎ２：通液塔
Ｎ３：通液塔
Ｒ：再生塔
Ｃ：強酸性カチオン交換樹脂層
Ａ：弱塩基性アニオン交換樹脂層
Ｆ：原料糖液
Ｐ：精製糖液[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for purifying a sugar solution, and more particularly, to a method for purifying a sugar solution using an ion exchange resin and having an improved regeneration step.
[0002]
[Prior art]
Conventionally, various methods using an ion exchange resin have been known as a method for purifying a sugar solution for the purpose of desalting and decoloring. For example, in the case of a starch sugar solution, the raw sugar solution is subjected to a purification process including a strongly acidic cation exchange resin tower, a weakly basic anion exchange resin tower, and a mixed resin tower of a strongly acidic cation exchange resin and a strongly basic anion exchange resin. Are known. In such a method, the regeneration step after the completion of the passage of the liquid is performed by supplying a necessary regenerant to each resin tower. In the case of a mixed resin tower, a backwash separation step of forming a separation layer for each resin by a difference in specific gravity of the resin after supplying washing water from the lower part of the tower to flow the resin, followed by a regeneration step Attached to
[0003]
When the regenerating agent is supplied until the resin in the column is completely regenerated in the step of regenerating the strongly acidic cation exchange resin tower, the amount of the regenerating agent used is enormous, which is extremely uneconomical. Therefore, an amount of regenerant required for complete regeneration is not supplied, and therefore, an unavoidable problem occurs in that impurities are constantly leaked from the resin before the resin breaks through in the next purification step. Such a problem occurs in the case of cocurrent regeneration in which the flow of the fluid is downflow in both the purification step and the regeneration step, and is prevented by countercurrent regeneration in which the purification step is downflow and the regeneration step is upflow. I can do it.
[0004]
However, when countercurrent regeneration is applied, it is necessary to supply holding water in a downward flow from the upper part of the resin layer in order to prevent fluidization of the resin layer at the time of regeneration, thereby increasing the amount of water used. There is. Further, when the concentration of the regenerant is increased, the resin layer is fluidized and the regeneration is not performed efficiently. Therefore, it is necessary to lower the concentration of the regenerant. Therefore, the dilution water for adjusting the concentration of the regenerant is required. There is also a problem that the amount of used is increased.
[0005]
By the way, in the purification step, the starch sugar solution is generally supplied at a temperature of 30 to 40 ° C., which is a condition suitable for the growth of bacteria. Bacteria grow on the inner wall surface of the tower where the sugar solution easily stays. Then, along with the decomposition of the sugar by the bacteria, weak acids such as organic acids and carbonates are newly generated, causing an increase in the load on the weakly basic anion exchange resin column of the second column, and the amount of the processing solution and the processing solution There is a concern that will decrease.
[0006]
Further, in the purification of sugar solutions, there is a high demand for continuous operation of the purification process by switching operation. However, a large number of towers are required for the switching operation (at least six towers are required in the above-mentioned conventional example), and it is desired to reduce the number of towers even slightly to reduce the construction cost and the operating cost.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to adopt a technique different from countercurrent regeneration, to prevent the problem of impurity leakage before resin breakthrough and to prevent the propagation of bacteria. It is an object of the present invention to provide an industrially advantageous method for purifying a sugar solution, which can be performed and can be performed with a small number of columns when the switching operation is performed.
[0008]
[Means for Solving the Problems]
That is, the gist of the present invention is a purification step in which a raw sugar liquid is passed from the top to a flow column in which a strongly acidic cation exchange resin layer and a weakly basic anion exchange resin layer are sequentially formed from the top, After the completion of the liquid passing in the process, the strongly acidic cation exchange resin layer of the liquid passing tower is transferred to the regeneration tower, the acid regenerant is supplied from the upper part of the tower, and the acid regenerant is supplied before the resin in the regeneration tower is completely regenerated. And a regeneration step of a weakly basic anion exchange resin in which an alkali regenerating agent is supplied from the top of the column to the wall of the flow-through column having an empty column in contact with the wall surface. After the regeneration of the weakly basic anion exchange resin, supply the regenerated strongly acidic cation exchange resin to the upper part of the flow column to re-form the strongly acidic cation exchange resin layer above the weakly basic anion exchange resin layer At that time, the upper and lower A step of separating the strongly acidic cation exchange resin layer into two or more layers having different regeneration rates, and sequentially supplying the strongly acidic cation exchange resin layer to the upper part of the liquid flow column from the upper section having a higher regeneration rate. It depends on the liquid purification method.
[0009]
In a preferred embodiment of the present invention, three or more liquid passing towers (N1, N2, N3...) And one regeneration tower are provided, and two liquid passing towers (N1, N2) are connected in series. After passing through the purification step, the downstream step (N2) and the downstream tower (N3) are used in series, followed by the purification step, and the upstream step. The column (N1) is subjected to a regeneration step and a purification preparation step. After the completion of the liquid passing in the purification step, the column (N1) is subjected to the purification step by using two liquid passing towers (N3, N1) in series, and the upstream side liquid is passed. The liquid tower (N2) is subjected to a regeneration step and a purification preparation step, and the above operation is sequentially repeated.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 to 5 are explanatory diagrams showing an example of a preferred embodiment of the present invention.
[0011]
The raw sugar liquid to which the present invention is applied will be described. The present invention is applied to all sugar solutions requiring desalting and decoloring. Examples of such sugar solutions include glucose sugar solution, isomerized sugar solution (glucose + fructose), starch sugar solution such as starch syrup, sugar alcohol such as sorbitol and maltitol, lactose-containing sugar solution, sucrose solution, and various other types of sugar solutions. Oligosaccharide solutions are mentioned.
[0012]
In the present invention, a strongly acidic cation exchange resin and a weakly basic anion exchange resin are used as the ion exchange resin. Examples of the strongly acidic cation exchange resin include Diaion (registered trademark, the same applies hereinafter) SK1B, SK110, PK216, PK212, and the like, Amberlite (registered trademark, the same applies hereinafter) 200CT, IR120B, IR124, IR118, and the like. Examples of the basic anion exchange resin include Diaion WA10, WA20, WA21, and WA30, and Amberlite XE583, IRA67, and IRA96SB.
[0013]
The strongly acidic cation exchange resin is regenerated with an acid regenerant (HCl or the like) and used as H-type, and the weakly basic anion exchange resin is regenerated with an alkali regenerator (NaOH or the like) and converted into an OH-type. It is subjected to a purification step. Then, desalting is performed by these ion exchange resins, and at the same time, decolorization is also performed.
[0014]
In the present invention, as described above, an aqueous hydrochloric acid solution is suitably used as the acid regenerating agent, and an aqueous sodium hydroxide solution is suitably used as the alkali regenerating agent. Usually, the concentration of the aqueous hydrochloric acid solution is 2 to 10% by weight, and the concentration of the aqueous sodium hydroxide solution is 2 to 5% by weight.
[0015]
The method for purifying a sugar solution according to the present invention includes a purification step, a regeneration step (I) of a strongly acidic cation exchange resin, a regeneration step (II) of a weakly basic anion exchange resin, and a purification preparation step. The sugar solution passing column is formed by forming a strongly acidic cation exchange resin layer (C) and a weakly basic anion exchange resin layer (A) sequentially from the top. The strongly acidic cation exchange resin layer (C) may be directly laminated on the weakly basic anion exchange resin layer (A), and the liquid is allowed to pass over the weakly basic anion exchange resin layer (A). However, a support mechanism that does not allow the resin to pass through may be provided, and a strongly acidic cation exchange resin layer (C) may be laminated thereon.
[0016]
The illustrated example is provided with three flow-through columns (N1, N2, N3) and one regeneration tower in order to make the operation of the purification process continuous by the switching operation. Then, the purification step is performed by using two flow-through columns (N1) and (N2) in series. According to such a two-column liquid passing method, there is an effect that the degree of purification can be increased. Usually, in one flow-through column, the strongly acidic cation exchange resin and the weakly basic anion exchange resin are usually packed in a ratio of 1: 0.6 to 1.0 (volume ratio).
[0017]
(1) As a purification step, the raw sugar liquid (from the upper part of the column) is passed through a liquid-passing column (N1) in which a strongly acidic cation exchange resin layer (C) and a weakly basic anion exchange resin layer (A) are sequentially formed from the top. F) Pass through the solution. Then, the purified sugar liquid (P) is recovered from the lower part of the flow tower (N2). The conditions for the purification step are not particularly limited, but usually, the liquid temperature is 30 to 50 ° C., and the liquid flow rate (space velocity) is 2 to 10 Hr ^{− with} respect to the weakly basic anion exchange resin layer (A) per one flow-through column. ^1. The end point of the liquid passing in the purification step by the two liquid passing towers (N1) and (N2) may be determined, for example, by a resin breakthrough phenomenon (impurity leak) in the upstream liquid passing tower (N1). I can do it. Such a leak of impurities can be determined by measuring the liquid quality (electric conductivity, absorbance, pH, etc.) at the outlet side of the flow-through tower (N1).
[0018]
(2) As a switching operation, after the completion of the flow in the purification step, the downstream flow column (N2) and the flow column (N3) are used in series to perform the purification step. As a result, the operation of the purification process is continuous. The conditions for the purification step are the same as described above. In addition, the determination of the end of the flow is performed in the same manner as described above.
[0019]
(3) On the other hand, after the completion of the liquid passing in the purification step by the liquid passing towers (N1) and (N2), the upstream liquid passing tower (N1) is subjected to a regeneration step and a purification preparation step. That is, the regeneration step (I) of the strongly acidic cation exchange resin, the regeneration step (II) of the weakly basic anion exchange resin, and the purification preparation step are performed.
[0020]
(3a) First, as a step (I) of regenerating a strongly acidic cation exchange resin, the strongly acidic cation exchange resin layer (C) of the flow-through tower (N1) is transferred to a regeneration tower (R), and an acid regenerant is added from the upper part of the tower. (HCl) is supplied and the supply of the acid regenerant is stopped before the resin in the regeneration tower (R) is completely regenerated. The transfer of the resin can be carried out, for example, by a resin discharge tube installed near the interface between the strongly acidic cation exchange resin layer (C) and the weakly basic anion exchange resin layer (A). The supply amount of the acid regenerating agent (HCl) depends on the concentration of the regenerating agent. In the case of 7 wt% HCl, the amount is usually 0.5 to 2.0 times the amount of the resin. As a result, the entire amount of the resin in the regeneration tower (R) is not regenerated, and as schematically shown, the regeneration rate decreases toward the lower part of the regeneration tower (R). Other conditions are not particularly limited, but usually, the liquid temperature is 10 to 40 ° C., and the liquid flow rate (space velocity) is 0.5 to 5.0 Hr ⁻¹ .
[0021]
(3b) Next, as a regeneration step (II) of the weakly basic anion exchange resin, an alkali regenerant (NaOH) is added to the flow-through column (N1) having an empty upper portion so as to contact the wall surface from the upper portion of the column. Supply. Examples of the mode of contact with the wall surface include a method of flowing down the wall surface and a method of filling the empty tower with an alkali regenerant. In the latter method, the space may be filled with water and then dissolved by adding an alkali.
[0022]
By the above-described operation, bacteria that are considered to be propagated on the inner wall surface of the liquid passing tower are sterilized, and the inner wall surface becomes an alkali state, so that the propagation of bacteria during the passage of the liquid in the next purification step is suppressed. The conditions of the regeneration step of the weakly basic anion exchange resin are not particularly limited, but in the case of 4 wt% NaOH, the supply amount is usually 1.0 to 3.0 times the resin amount, and the liquid temperature is 10 times. ４０40 ° C., and the liquid flow rate (space velocity) is 0.5-5.0 Hr ⁻¹ .
[0023]
(3c) Then, as a purification preparation step, after the regeneration of the weakly basic anion exchange resin is completed, the regenerated strongly acidic cation exchange resin is supplied to the upper part of the flow-through column (N1) to supply a weakly basic anion exchange resin layer ( The strongly acidic cation exchange resin layer (C) is reformed on the upper part of A). At this time, the strongly acidic cation exchange resin layer is divided into two or more layers having different regeneration rates in the vertical direction in the regeneration tower (R), and the upper section having the higher regeneration rate is sequentially placed on the upper part of the liquid passing tower (N1). Supply. In the illustrated example, the strongly acidic cation exchange resin layer in the regeneration tower (R) is divided into three layers. In addition, since there is a distribution of the regeneration rate in each layer, it is preferable to mix them when supplying to the upper part of the liquid passing column (N1). According to such a purification preparation step, it is possible to prevent leakage of impurities before the resin breakthrough without performing countercurrent regeneration.
[0024]
(4) As the switching operation, after the completion of the liquid passing in the purification step by the two liquid passing towers (N2) and (N3), the downstream liquid passing tower (N3) and the liquid passing tower (N1) are connected in series. And used in the purification process.
[0025]
(5) On the other hand, after the completion of the liquid passing in the purification step by the liquid passing towers (N2) and (N3), the liquid passing tower (N2) is subjected to a regeneration step and a purification preparation step.
[0026]
(6) The above operations (1) to (5) are sequentially repeated. In addition, although the description is omitted, usually, in a flow-through column that switches from the purification process to the regeneration process, a water-washing process for recovering the remaining sugar solution in the column is provided as a conventional means, and in each of the regeneration processes described above. After completion of the supply of the regenerant, a water washing process for extruding the regenerant is provided as a conventional means.
[0027]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.
[0028]
In the following examples, the operation of the purification step was continuously performed by the switching operation according to the method shown in FIGS. However, descriptions of a water washing process for recovering the sugar liquid remaining in the flow-through tower after the purification step and a water washing process for extruding the regenerant after the supply of the regenerant has been omitted are omitted. The three liquid passing towers (N1, N2, N3) and the one regeneration tower were configured as follows.
[0029]
<Flow-through tower>
A tower having an inner diameter of 20 mm and a height of 1 m is sequentially filled with 90 ml of a strongly acidic cation exchange resin (“SK1B” manufactured by Mitsubishi Chemical Corporation) and 100 ml of a weakly basic anion exchange resin (“WA30” manufactured by Mitsubishi Chemical Corporation) from the top. A liquid flow column having a liquid inlet tube at the upper part and a liquid outlet tube at the lower part, and having a resin discharge tube near the interface between the strongly acidic cation exchange resin layer and the weakly basic anion exchange resin layer was used. The three liquid passing towers (N1, N2, N3) were connected to each other so as to be switchable.
[0030]
<Regeneration tower>
A liquid introduction pipe is provided at the upper part of the tower having an inner diameter of 20 mm and a height of 0.5 m, and a liquid discharge pipe is provided at a lower part. An intermediate extraction pipe (upper intermediate extraction pipe and lower intermediate extraction pipe) was installed, and a regeneration tower provided with a lower tower extraction pipe at the bottom of the tower was used.
[0031]
Example 1
The following operations (1) to (5) were repeated to continuously purify the glucose solution (sugar concentration 30% by weight) roughly decolorized by activated carbon treatment.
[0032]
(1) The raw sugar liquid (F) was passed through the liquid passing tower (N1) from the top of the tower. Then, the purified sugar solution (P) was recovered from the lower part of the liquid passing tower (N2). The liquid temperature is 40 ° C., and the liquid flow rate (space velocity) is 5 Hr ⁻¹ with respect to the weakly basic anion exchange resin of each liquid passing sugar. The resin breakthrough phenomenon (leakage of impurities) in the liquid passing tower (N1) was confirmed, and the liquid passing in the purification step by the two liquid passing towers (N1) and (N2) was completed.
[0033]
(2) After the completion of the liquid passing, the process was switched to a purification step using the liquid passing column (N2) and the liquid passing column (N3) in series.
[0034]
(3) On the other hand, after the completion of the liquid passing in the purification step by the liquid passing towers (N1) and (N2), the liquid passing tower (N1) is subjected to a regeneration step and a purification preparation step. That is, the regeneration step (I) of the strongly acidic cation exchange resin, the regeneration step (II) of the weakly basic anion exchange resin, and the purification preparation step were performed.
[0035]
(3a) First, as the regeneration step (I) of the strongly acidic cation exchange resin, the strongly acidic cation exchange resin layer (C) of the flow-through tower (N1) was transferred to the regeneration tower (R). The transfer of the resin was performed by a resin discharge tube installed near the interface between the strongly acidic cation exchange resin layer (C) and the weakly basic anion exchange resin layer (A). Then, an acid regenerant (7% by weight hydrochloric acid aqueous solution) was supplied from the upper part of the regeneration tower (R). The supply amount of the acid regenerant is 1 volume times the amount of the resin, the liquid temperature is normal temperature, and the liquid flow rate (space velocity) is 2 Hr ^-1 .
[0036]
(3b) Next, as a regeneration step (II) of the weakly basic anion exchange resin, the wall is allowed to flow down from the upper part of the flow-through tower (N1) having an empty upper part from the upper part of the tower, and an alkali regenerant (4% by weight water) (Aqueous sodium oxide solution). The supply amount of the alkali regenerant is 1.5 times the amount of the resin, the liquid temperature is normal temperature, and the liquid flow rate (space velocity) is 2 Hr ^-1 .
[0037]
(3c) Then, as a purification preparation step, after the regeneration of the weakly basic anion exchange resin is completed, the regenerated strongly acidic cation exchange resin is supplied to the upper part of the flow-through column (N1) to supply a weakly basic anion exchange resin layer ( The strongly acidic cation exchange resin layer (C) was reformed on the upper part of A). At this time, the strongly acidic cation exchange resin layer in the regeneration tower (R) is divided into three layers, and the upper middle extraction pipe, the lower intermediate extraction pipe, and the lower extraction pipe of the regeneration tower (R) are used to form an upper layer. It was supplied to the upper part of the liquid passing tower (N1) sequentially from the side.
[0038]
(4) After the completion of the refining step in the refining step using the liquid passing towers (N2) and (N3), the process was switched to a purification step using the liquid passing tower (N3) and the liquid passing tower (N1) in series.
[0039]
(5) On the other hand, after the completion of the liquid-passing in the purification step by the liquid-passing towers (N2) and (N3), the liquid-passing tower (N2) was subjected to a regeneration step and a purification preparation step. Then, the above operations (1) to (5) were sequentially repeated three times. Table 1 shows the quality of the purified sugar solution. As is clear from Table 1, the liquid quality is extremely high. Also, no reduction in processing capacity due to repeated operations was observed. In addition, the coloring degree in a table | surface is a value of the light absorbency measured at the wavelength of 420 nm using a 100-mm cell.
[0040]
[Table 1]

[0041]
【The invention's effect】
According to the present invention described above, a technique different from countercurrent regeneration is adopted, there is no problem of impurity leakage before resin breakthrough, bacteria can be prevented from growing, and switching operation is not performed. In this case, an industrially advantageous method for purifying a sugar solution can be provided which requires only a small number of columns.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a preferred embodiment of the present invention (purification step)
FIG. 2 is an explanatory view showing an example of a preferred embodiment of the present invention (regeneration step (I)).
FIG. 3 is an explanatory view showing an example of a preferred embodiment of the present invention (regeneration step (II)).
FIG. 4 is an explanatory view showing an example of a preferred embodiment of the present invention (purification preparation step).
FIG. 5 is an explanatory view showing an example of a preferred embodiment of the present invention (purification step).
[Explanation of symbols]
N1: Liquid passing tower N2: Liquid passing tower N3: Liquid passing tower R: Regeneration tower C: Strongly acidic cation exchange resin layer A: Weakly basic anion exchange resin layer F: Raw sugar liquid P: Purified sugar liquid

Claims

A purification step in which the raw sugar liquid is passed from the top to a flow column in which a strongly acidic cation exchange resin layer and a weakly basic anion exchange resin layer are sequentially formed from the top, and Transfer the strongly acidic cation exchange resin layer of the liquid tower to the regeneration tower, supply the acid regenerant from the top of the tower, and stop the supply of the acid regenerant before the resin in the regeneration tower is completely regenerated A regeneration step of an exchange resin, a regeneration step of a weakly basic anion exchange resin for supplying an alkali regenerant in a manner to contact the wall from the top of the column with an empty tower at the top, and a weakly basic anion exchange resin After the completion of the regeneration, the regenerated strongly acidic cation exchange resin is supplied to the upper part of the liquid passing column to re-form the strongly acidic cation exchange resin layer above the weakly basic anion exchange resin layer. At least two layers with different vertical playback rates Dividing the strongly acidic cation-exchange resin layer, the purification method of the sugar solution, characterized in that it comprises the purified preparation step for supplying sequentially on top of the liquid passage column from sections of high reproduction rates top.

It is equipped with three or more liquid flow towers (N1, N2, N3 ...) and one regeneration tower, and is subjected to a purification step by using two liquid flow towers (N1, N2) in series to perform purification. After the completion of the flow in the process, the downstream flow column (N2) and the flow column (N3) are used in series for the purification step, and the upstream flow column (N1) is regenerated and prepared for purification. After passing through the purification step, the purification step is carried out by using two flow towers (N3, N1) in series, and the upstream flow tower (N2) is subjected to the regeneration step and the purification step. 2. The method for purifying a sugar solution according to claim 1, wherein the sugar liquid is subjected to a preparation step and the above operations are sequentially repeated.