JP4220168B2

JP4220168B2 - Stirring apparatus and stirring method for liquid containing solid particles

Info

Publication number: JP4220168B2
Application number: JP2002069042A
Authority: JP
Inventors: 彰久神田; 泰弘鷲見
Original assignee: Kaneka Corp
Current assignee: Kaneka Corp
Priority date: 2002-03-13
Filing date: 2002-03-13
Publication date: 2009-02-04
Anticipated expiration: 2022-03-13
Also published as: JP2003265941A

Description

【０００１】
【発明の属する技術分野】
本発明は、層流域から乱流域における広範囲の撹拌に関し、特に固−液系の混合、固−液系の反応、固―液系の物質移動、固―液系の熱移動、気−液−固系の反応、気−液−固系の物質移動、気−液−固系の熱移動、晶析、固定化酵素反応，担体への菌体の固定化操作、高濃度のスラリーの混合および反応，等の処理を効率良く行う為の撹拌装置及び撹拌方法に関する。
【０００２】
【従来の技術】
比重差のある２相以上の物質の撹拌混合を行うには、特に上下方向の強い流れを生じせしめる必要がある。そのための撹拌翼としては種々のものが用いられるが、撹拌槽の高さと径の比が大きくなるに従い、効果的に混合を行うのは難しくなる。
【０００３】
小型のタービン翼やＨ型翼を単独、あるいは複数設置した場合、半径方向への吐出流が強く、槽内の流れは撹拌槽の軸方向高さの中心で分離するため、上下の循環が悪くなる。また、局所的な剪断力が強くなるために、壊れやすい固体粒子、例えば固定化酵素などを反応に用いる場合には適さない。
【０００４】
傾斜タービン翼やプロペラ翼、傾斜パドル翼などを用いることにより、上下方向の軸流を発生させることもできるが、これらの撹拌翼では翼回転数を上げる必要があるため局所的な剪断力がかかること、軸流は翼近傍にのみ強く発生し、槽全体を均一に混合することは困難であることから、タービン翼を用いた場合と同様の問題を抱えている。
【０００５】
また、
ＪｏｕｒｎａｌｏｆＣｈｅｍｉｃａｌＥｎｇｉｎｅｅｒｉｎｇｏｆＪａｐａｎ、Ｖｏｌ．３２，Ｎｏ．１のｐ．４０−４４、１９９９に記載してある、ＫＯＪＩＴＡＫＡＨＡＳＨＩａｎｄＳＨＩＮ−ＩＣＨＩＲＯＳＡＳＡＫＩ；“ＣｏｍｐｌｅｔｅＤｒａｗｄｏｗｎａｎｄＤｉｓｐｅｒｓｉｏｎｏｆＦｌｏａｔｉｎｇＳｏｌｉｄｓｉｎＡｇｉｔａｔｅｄＶｅｓｓｅｌＥｑｕｉｐｐｅｄｗｉｔｈＯｒｄｉｎａｒｙＩｍｐｅｌｌｅｒｓ”の中では、タービン翼及び傾斜パドル翼を用いて液体より軽い粒子を混合する撹拌条件について論じているが、この従来技術では固体粒子の体積濃度が最大で約１０．３ｖｏｌ％までと限定される。
【０００６】
一方、高粘性流体の撹拌に用いられる大型のパドル翼では、固体粒子を多く含む低粘性流体を混合する場合、撹拌消費動力が非常に大きくなり運転コストが問題となる。また、ダブルヘリカルリボン翼ではそれらの流体が撹拌翼と共廻りし、混合が促進されない。
【０００７】
例えば，これまでにも，広範囲の粘度領域において，撹拌槽内の全体混合を目的とした撹拌装置の開発が進められており，特開平８−２４６０９，特開平５−４９８９０，特開平９−７５６９９，特開平８−７１３９８，特開平７−１２４４５６などにおいては，各種パドル翼を多段に配置した撹拌翼が用いられている。しかしながら，流体が固体粒子を多く含む場合，上下に配置される多段パドル翼からなる撹拌翼を用いるとそれぞれの撹拌翼による吐出流が干渉し、槽内の軸方向の循環を大きく妨げ，必ずしも適切な撹拌操作が行えない。
【０００８】
また，特開平９−１０８５５７，特開平１０−２４２３０の撹拌装置では，ボトムパドルの上部に格子翼が配置されたものが提案されているが，固体粒子を含む流体に対しては，効果的でない場合もあり，特に撹拌軸から半径方向へ伸びる帯状の部材が存在する場合は，その部分がパドル翼と同様に吐出流を形成し，やはり上下の流れを妨げてしまう。
【０００９】
更に、特開２０００−２１０５４９においては，固体粒子の停滞を防止する装置が提案されているが，その先行技術では，固体粒子の比重が重く，槽底部に停滞する場合を想定している。
【００１０】
【発明が解決しようとする課題】
このように、固体と液体の二相をできるだけ均一に混合するためには、局所的な剪断力の発生を抑えつつ、上下方向の流れを発生させるとともに、その上下方向の流れには、比重差による粒子の浮力または重力に打ち勝つだけの強さがなければならない。特に、固体粒子を多量に含む流体を混合する場合は、これら粒子の停滞部が発生しないようにする必要がある。本発明は、このような流れを実現させ、固体粒子と液体の混合液を均一に混合する撹拌装置及び撹拌方法を提供しようとする。
【００１１】
【課題を解決するための手段】
上記課題を解決するために、本発明の撹拌装置の要旨とするところは、
固体粒子と液体の混合液を入れる撹拌槽と、
前記撹拌槽内に前記混合液の静止液面に対して略垂直に配置した撹拌軸と、
前記撹拌軸の最下段に支持された幅広攪拌翼と、
前記幅広攪拌翼の上方に順次段状に配されて該撹拌軸に各々支持された複数の櫛状翼と、
を含み、
前記幅広攪拌翼は前記攪拌槽の底部に位置し、
前記幅広攪拌翼に隣接する櫛状翼である中段櫛状翼は、該幅広攪拌翼に、前記攪拌軸の回転方向へ９０度未満の角度で先行して配置され、かつ前記撹拌軸の軸方向に該幅広攪拌翼と重なりを有し、
前記中段櫛状翼以外の櫛状翼である上段櫛状翼は、下方に隣接する櫛状翼に、前記攪拌軸の回転方向へ９０度未満の角度で先行して配置され、かつ前記撹拌軸の軸方向に該下方に隣接する櫛状翼と重なりを有し、
各前記上段櫛状翼の翼長は、下方に隣接する櫛状翼の翼長より短く、
撹拌の停止時に、最上段の前記櫛状翼の一部が前記混合液の静止液面から突出しない撹拌装置であることにある。
【００１２】
前記上段櫛状翼は、１段であり得る。
【００１３】
各前記櫛状翼の翼長は、前記下方に隣接する櫛状翼の翼長の０．５〜０．９倍であり得る。
【００１４】
前記撹拌装置においては、静止液面と前記最上段の櫛状翼の上端との間の距離が、前記混合液の静止液深の０〜５％であり得る。
【００１５】
前記撹拌装置においては、前記中段櫛状翼の長手に沿い、前記撹拌軸から前記中段櫛状翼の先端部にそれぞれ向かう方向が、前記撹拌軸と垂直の方向に対し、上又は下に５〜７５度の間の一定の傾きを持ち、
各前記上段櫛状翼の長手に沿い、前記撹拌軸から各前記上段櫛状翼の先端部に向かう方向が、前記撹拌軸と垂直の方向に対し、前記一定の傾きを持ち得る。
【００１６】
前記一定の傾きは、上又は下に２５〜３５度であり得る。
【００１７】
前記撹拌装置においては、前記撹拌槽内の壁に複数の邪魔板を縦方向に装着させ得る。
【００１８】
前記撹拌装置においては、前記中段櫛状翼と前記幅広撹拌翼との、前記幅広撹拌翼の下端から前記最上段櫛状翼の上端までの軸方向の高さに対する重なり度は、２．５〜５％であり得る。
【００１９】
前記撹拌装置においては、各前記櫛状翼と前記下方に隣接する櫛状翼との前記幅広撹拌翼の下端から前記最上段櫛状翼の上端までの軸方向の高さに対する重なり度は、２．５〜５％であり得る。
【００２０】
また、本発明の要旨とするところは、
固体粒子と液体の混合液を撹拌槽に入れ、
該撹拌槽に配置した撹拌軸を回転させて該混合液を撹拌して該撹拌軸を中心とする渦を形成し、
該渦が形成された該混合液の液面に沿い下降する流れを生じさせ、
該下降する流れを該撹拌槽の底部で反転させて該撹拌槽の内壁面に沿う上昇する流れとなし、
該混合液の上部で再び反転させて循環させるようにした
ことを特徴とする混合液の撹拌方法であることにある。
【００２１】
前記混合液の撹拌方法においては、前記のいずれかの撹拌装置を用い得る。
【００２２】
前記混合液の撹拌方法においては、前記固体粒子の比重が前記液体の比重より小であり得る。
【００２３】
前記混合液の撹拌方法においては、前記固体粒子がペレット状の樹脂であり得る。
【００２４】
前記混合液の撹拌方法においては、前記混合液の前記固体粒子の体積濃度が１５〜４２vol.%であり得る。
【００２５】
【発明の実施の形態】
図１は本発明の撹拌装置１０の基本構成を示す概略図である。撹拌槽１内中心部には撹拌軸２が配設されている。符号３は２枚の幅広撹拌翼３ａ、３ｂから成る２枚パドル翼（以下パドル翼と称す）で、撹拌軸２の下端部に装着されている。符号４ａ、４ｂは、最下段に位置するパドル翼３に対して、その上に隣接する中段櫛状翼を示す。符号５ａ、５ｂは、最上段に位置する上段櫛状翼を示す。
【００２６】
中段櫛状翼４ａは、幅広撹拌翼３ａに対して４５度の角度で回転方向に対して先行させて配置され、かつ、幅広撹拌翼３ａとは、幅広撹拌翼３ａの下端から上段櫛状翼５ａ、５ｂの上端までの軸方向高さｈの４．４％の長さの重なりΔｈ_１を有する（図２においてΔｈ_１／ｈ＝０．０４４）。本明細書においては、このようなある翼と他の翼との重なりΔｈの、幅広撹拌翼３ａの下端から上段櫛状翼５ａ、５ｂの上端までの軸方向高さｈに対する割合を％で表示した値を重なり度と定義する。
【００２７】
上段櫛状翼５ａは中段櫛状翼４ａに対して４５度の角度で回転方向に対して先行させて配置され、かつ、中段櫛状翼４ａとは、ｈの４．４％の長さの重なりΔｈ_２を有する（図２においてΔｈ_２／ｈ＝０．０４４）。また、この上段櫛状翼５ａ、５ｂ形状は、中段櫛状翼４ａ、４ｂとは形状が異なり、中段櫛状翼４ａ、４ｂの外側の櫛を除いたもので、且つ、上段櫛状翼５ａ、５ｂの水平方向の翼長ｄ_２が、中段櫛状翼４ａ、４ｂの水平方向の翼長ｄ_１の６０％である（ｄ_２／ｄ_１＝０．６；図２）。尚、本明細書において、幅広撹拌翼、櫛状翼の翼長は、図２に示すように、水平方向の翼長とする。
【００２８】
邪魔板６は槽径Ｄの４．８％幅のもの２枚を槽の周方向に関し１８０度の位置に配置している。邪魔板６と槽内壁面７とは槽径Ｄの５％のギャップｄｇを設けている。底は皿型鏡板８とし、パドル翼３の下側の縁部９は、皿型鏡板８より一定の間隔ｗを保つようにしており、その間隔ｗは、ｈに対して１．８％である（図２においてｗ／ｈ＝０．０１８）。
【００２９】
邪魔板６の枚数、内壁７とのギャップｄｇおよび、パドル翼３と皿型鏡板８との間隔ｗは、槽の大きさ、投入される粒子の大きさ、量、比重などによって変えてもよい。また、皿型鏡板８は、皿型の他、平型、欠球面型、半球面型、欠半楕円体面型においても、本発明の効果は発揮され得る。
【００３０】
図３は、本発明に係る撹拌装置１０の横断面図である。本発明に用いる撹拌槽１としては、槽内に槽外から回転駆動可能な撹拌軸２を設置し使用することができる。
【００３１】
撹拌槽１の形状としては、円筒形、円錐形、断面楕円形の円筒等が挙げられるが、良好な混合、流動を得る理由から円筒形が好ましい。また、槽の底部は液循環と流動性から下に凸の凹面鏡形の鏡板から成ることが好ましい。
【００３２】
撹拌槽１及びパドル翼３、中段櫛状翼４ａ、４ｂ、上段撹拌翼５ａ、５ｂの材質は、特に限定されることはないが材質の強度、耐熱性及び耐食性を考慮してオーステナイト系又はフェライト系ステンレス製鋼が好ましく、使用する液体により適宜選定されるが、経済的な理由から特に好ましくは、オーステナイト系ステンレス製鋼のSUS304、SUS316、SUS316Lである。
【００３３】
撹拌軸２は静止液面に対して略垂直に配置する。槽内のいずれの位置に設置しても良いが、良好な混合、流動を得る理由から槽内中心部に鉛直に設置するのが好ましい。
【００３４】
幅広撹拌翼３ａ、３ｂから成るパドル翼３は撹拌槽１の槽底部に設置され、下部は槽底部に近接しており、幅広撹拌翼３ａ、３ｂの上下幅ｈｏの、静止時の液深（静止液深）Ｈに対する比ｈｏ／Ｈは、良好な撹拌状態を得るうえで、好ましくは０．２５以上、さらに好ましくは０．３以上である。パドル翼３の翼長ｄの槽径Ｄに対する比ｄ／Ｄは、良好な撹拌状態を得るうえで、好ましくは０．３５以上、さらに好ましくは０．４５以上である。また、ｈｏ／Ｈの上限はパドル翼に対する吐出流が直ちにそのパドル翼上部に戻らない程度の高さであり、ｄ／Ｄの上限は撹拌槽１及び邪魔板６その他設備に接触するようなことがない程度の大きさである（図２）。
【００３５】
また、パドル翼３としては、従来公知の平板状のものをほぼ制限無く用いることが可能で、パドル翼３は波打った構造を有していてもかまわない。
【００３６】
さらに、パドル翼３、中段櫛状翼４ａ、４ｂ、上段撹拌翼５ａ、５ｂから成る撹拌翼全体の合計高さｈの静止液深Ｈに対する高さ比ｈ／Ｈは、良好な撹拌状態を得るうえで、０．７以上、且つ、１．０未満、さらに好ましくは０．９４〜０．９６である。
【００３７】
特に上記高さ比ｈ／Ｈが０．９４〜０．９６の場合には、撹拌軸２回りの液面付近にボルテックス（渦）が形成され、固体粒子を含む流体の巻き込みを促進するという点で有利となる。
【００３８】
ここで、ボルテックスとは、撹拌翼の回転によって槽内の液体が回転運動し、その結果、槽中心付近の動圧が低下することによって撹拌槽中心付近の液面が槽底部方向へ凹む現象を言う。
【００３９】
上記高さ比が０．７未満である場合、液面と上段撹拌翼５ａ、５ｂの各上端との間隔が大きくなり、槽内の流線が一筆書き状態ではなくなり、上下方向に複数の渦が存在するような状態となり、槽内の混合性能を低下させる傾向がある。又、上段撹拌翼５ａ、５ｂが走査しない液面近傍では液の循環流れが遅くなり、停滞してしまう部分が発生しやすく混合効率が悪くなる。
【００４０】
反対に、高さ比が１．０以上の場合には、上段撹拌翼５ａ、５ｂの回転に伴い液面付近にある固体粒子が半径方向へ散乱する。そのため、槽底部に配設されたパドル翼３によって生成された吐出流が、邪魔板６によって上昇流に変換されても、この上昇流と上述の散乱した固体粒子が衝突し撹拌槽１内の流れを悪くする。
【００４１】
本発明における撹拌翼全体は、最下段に撹拌槽１の槽底部に配設される幅広平板からなるパドル翼３を、その上方に数段にわたって複数の櫛状の翼（中段櫛状翼４ａ、４ｂ、上段撹拌翼５ａ、５ｂなど）を配置する。この櫛状の翼は何段設けてもよいが、櫛状の翼を２段配置する場合について説明する。
【００４２】
上述の最下段に配設された幅広平板からなるパドル翼３の上方に、中段櫛状翼４ａ、４ｂ、上段撹拌翼５ａ、５ｂを配置する。ここで、図３に示すように、最下段のパドル翼の上に隣接する中段の櫛状翼を、９０度未満の角度αで回転方向に対してパドル翼３に先行させて配置する。好ましくは、各段の翼の吐出流の干渉の度合いを小さくし、撹拌軸２が偏芯するような力を小さくするように、この角度を４０〜５０度とする。図３においては、角度αは４５度である。
【００４３】
なお、中段櫛状翼４ａ、４ｂはそれぞれの長手方向が１平面に含まれるように配置されている。上段櫛状翼５ａ、５ｂも、それぞれの長手方向が１平面に含まれるように配置されている。中段櫛状翼４ａの長手方向を含む平面と、中段櫛状翼４ｂの長手方向を含む平面とが所定の角度をなしていてもよい。又、中段櫛状翼は３個以上備えられてもよい。上段櫛状翼５ａの長手方向を含む平面と、上段櫛状翼５ｂの長手方向を含む平面とが所定の角度をなしていてもよい。又、上段櫛状翼は３個以上備えられてもよい。幅広撹拌翼３ａ、３ｂも、それぞれの長手方向が１平面に含まれるように配置されている。幅広撹拌翼３ａの長手方向を含む平面と、幅広撹拌翼３ｂの長手方向を含む平面とが所定の角度をなしていてもよい。幅広撹拌翼は３個以上備えられて多数枚の幅広撹拌翼から成るパドル翼が形成されていてもよい。
【００４４】
また、パドル翼と中段櫛状翼４ａ、４ｂは撹拌軸方向に関して重なりを有する。好ましくは、各段の翼からの吐出流が孤立した局所的な渦にならないように、この重なりΔｈ_１のｈ（幅広撹拌翼３ａの下端から上段櫛状翼５ａ、５ｂの上端までの軸方向高さ）に対する比（重なり度）Δｈ_１／ｈは２．５％以上が好ましい。３〜５％であることが更に好ましい。
【００４５】
同様に、中段櫛状翼４ａの上に隣接する上段櫛状翼５ａは、中段櫛状翼４ａに対して回転方向に先行させ、撹拌軸２方向に対して重なりを持たせて配置する。この重なりΔｈ_２のｈに対する比（重なり度）Δｈ_２／ｈは、各段の翼からの吐出流が孤立した局所的な渦にならないようにするうえで、２．５％以上が好ましい。３〜５％であることが更に好ましい。
【００４６】
中段櫛状翼４ｂの上に隣接する上段櫛状翼５ｂは、中段櫛状翼４ｂに対して回転方向に先行させ、撹拌軸２方向に対して重なりを持たせて配置する。
【００４７】
また、中段櫛状翼４ａ、４ｂは幅広撹拌翼３ａ、３ｂと翼長が等しくても、異なっていてもよいが、図２のように、上段櫛状翼５ａ、５ｂの翼長の、中段櫛状翼４ａ、４ｂの翼長に対する比ｄ_２／ｄ_１は、０．５〜０．９とすることが好ましい。より好ましくは０．５５〜０．６５である。
【００４８】
また、中段櫛状翼４ａ、４ｂの、櫛歯の本数と、上段櫛状翼５ａ、５ｂの、櫛歯の本数とは、等しくしても、上段櫛状翼５ａ、５ｂの櫛歯の本数が、中段櫛状翼４ａ、４ｂの、櫛歯の本数より少なくてもよい。中段櫛状翼４ａ、４ｂと、上段櫛状翼５ａ、５ｂのそれぞれの長手方向は、撹拌軸２に対して垂直ではなく，図２ように撹拌軸２に垂直な方向に対して傾きを持たせる構成としてもよい。好ましくは、この傾き角βは上若しくは下に５〜７５度であり、さらに好ましくは、この部材による吐出流が顕著でなくなり、且つ、製作が容易である構造とするため、この角度は上又は下に２５〜３５度が良い。図２においては、傾き角βは３０度である。
【００４９】
さらに、撹拌槽１の側壁面７に、撹拌槽１の底部から静止液面の位置まで連続して撹拌軸２方向に延びる邪魔板６を配設してもよい。邪魔板６はパドル翼３から吐出された流れを上昇流に変える効果があり、好ましい。
【００５０】
邪魔板形状は翼に接触しなければ特に限定はないが、例えば平板型や特開平０９−０５２０３７に示されたような傾斜型であってもよく、邪魔板は複数枚設置しても良い。好ましくは、固体粒子を多く含む場合には邪魔板の背面に液の停滞部が発生しやすいので平板型で２枚又は３枚がよい。
【００５１】
また、このときの邪魔板６の幅ｄ^‘は、槽径Ｄに対して３％〜１０％である（図２）。この幅ｄ^‘は、槽底に配置されたパドル翼３からの吐出流を上昇流に好適に変換できる幅であり、固体粒子を多く含む場合には邪魔板６の背面に液の停滞部が発生しないように槽径Ｄに対して４〜６％程度が更に好ましい。
【００５２】
本発明に係る撹拌装置は、固体粒子と液体の混合液を均一に混合する目的で好適に用いられる。本発明に用いる液体としては、特に限定されないが、水に代表されるような低粘度の無機溶剤であり、固体粒子が合成樹脂製でない場合又は合成樹脂製の固体粒子が有機溶剤に容易に溶解しない場合又は不溶な場合には、有機溶剤（炭化水素類、ハロゲン化炭化水素類、アルコール類、フェノール類、エーテル類、アセタール類、ケトン類、脂肪酸類、酸無水物類、エステル類、窒素化合物類、硫黄化合物類、２つ以上の官能基を持つ化合物）でも良い。
【００５３】
本発明で用いる固体粒子としては、特に限定されないが、合成樹脂製であり、例えば、ビニール系樹脂（ポリ塩化ビニール、ポリ塩化ビニリデン、ポリ酢酸ビニル、ポリビニールアルコール）、フッ素樹脂（４フッ化エチレン、４フッ化・６フッ化プロピレン、４フッ化エチレンパーフロロアルコ櫛エチレン共重合体、４フッ化エチレンエチレン共重合体、３フッ化塩化エチレン、フッ化ビニリデン）、ポリスチレン系樹脂（ポリスチレン、スチレン・アクリルニトリル・ブタジエン共重合体）、ポリエチレン系樹脂（低密度ポリエチレン、高密密度ポリエチレン、エチレン・酢酸ビニール共重合体）、ポリアミド（６ナイロン、１１−ナイロン）、ポリアセタール、ポリフェニレン・オキサイド、ポリカーボネイト、ポリプロピレン、ポリ４―メチルデンテン、ポリメチルメタクリレート、酢酸セルロースズ、アイオノマー、ポリウレタン、ポリエステルエラストマー、ポリエルテル、ゴム類（エチレン・プロピレンゴム、クロロプレンゴム、クロロスルフォン化ポリエチレン、ニトリルゴム、アクリルゴム、イソプレンゴム、スチレン・ブタジエンゴム、ブチルゴム、エピクロルヒドリンゴム、ウレタンゴム、多流化ゴム、シリコーンゴム、フッ素ゴム、天然ゴム）等が挙げられる。
【００５４】
固体粒子の形状としては、球形、楕円体、円盤、円柱、四面体、六面体、八面体、十二面体や不規則形状などがあり、限定されるのでものでない。形状には限定されないが、ペレット状（柱状）であり短径と長径の分数比が１／５〜５であることが好ましい。この分数比が１／５より小さい場合や５より大きい場合には液体中で固体粒子が絡み合い、非ニュートン流体としての挙動を示し、槽内の流れが円滑でなくなる。
【００５５】
また、固体粒子の寸法としては、その長径が０．５〜２０mmであり、好ましくは１〜４mmである。さらに、固体粒子の比重は、液体の比重の０．５〜２．５倍であり、液との比重差による重力又は浮力に抵抗して円滑に流動させるためには、固体粒子の比重は特に好ましい範囲として液体の比重の０．７〜１．３倍で、更に好ましくは、０．７〜１．０倍である。
【００５６】
これらの固体粒子の体積濃度は、１〜４２vol%の範囲であっても本発明の撹拌翼を用いることにより、停滞部がなく円滑に流動する。特に、固体粒子の体積濃度が濃度範囲１５〜４２vol％において本発明の撹拌装置は更に効果を発揮する。上述のように従来の撹拌装置による撹拌では、固体粒子の体積濃度が１０．３vol％未満では撹拌が良好に行なわれるが、本発明においては、濃度範囲１５〜４２vol％においても撹拌が良好に行なわれる。
【００５７】
以上の方法により、固体と液体の二相をできるだけ均一に混合するためには、局所的な剪断力の発生を抑えつつ、上下方向の流れを発生させるとともに、その上下方向の流れには、比重差による粒子の浮力または重力に打ち勝つだけの強さが求められる。特に、固体粒子を多量に含む流体を混合する場合においても、これら流体の停滞部を発生させないことが必要である。
【００５８】
上記構成を特徴とする本発明に係る撹拌装置１０により、多量の固体粒子を含む液体であっても、撹拌槽１の底壁面付近に配設される幅広平板からなるパドル翼３により吐出された液体が、撹拌槽１の内壁及び邪魔板６に衝突し上昇する。このとき、パドル翼３の上に隣接する中段櫛状翼４ａ、４ｂの櫛状の翼を９０度未満の角度で回転方向にパドル翼３に対して先行させて配置されること、且つ、パドル翼３と中段櫛状翼４ａ、４ｂとが、撹拌軸２の方向に重なりを有することによりこの中段櫛状翼４ａ、４ｂより吐出される液がパドル翼から吐出された液体の上昇を妨げない。
【００５９】
また、全体撹拌翼のうち、中段櫛状翼４ａ、４ｂを櫛状とすることにより、中段櫛状翼４ａ、４ｂから吐出される流れを少ないものとしている。すなわち、槽の中間高さの撹拌される部分において、下段のパドル翼３からの吐出された流れと中段櫛状翼４ａ、４ｂからの吐出により発生する流れがお互いに干渉しあって流れを打ち消すということがない。
【００６０】
最上段の上段櫛状翼５ａ、５ｂについても中段櫛状翼４ａ、４ｂに対して９０度未満の角度で回転方向に先行させて配置され、且つ、撹拌軸２の方向に重なりを有し、且つ、上段櫛状翼５ａ、５ｂの翼長を中段櫛状翼４ａ、４ｂの翼長の約６０％とすることにより、撹拌槽の内壁に沿って上昇してきた液体と最上段から吐出される液体との衝突を防ぎ、液体の液面付近、且つ、邪魔板６付近において液体を停滞させない。
【００６１】
また、最上段の上段櫛状翼５ａ、５ｂの翼長を短くし、且つ、上段櫛状翼５ａ、５ｂの翼を静止液深の０〜５％の高さ分静止液面より沈めた位置に配置することにより、撹拌中の液面の上部の空中への液体中の固体粒子の飛散を大幅に抑制することができる。従って、撹拌翼によって伝達される運動エネルギーを効率よく液体に伝達できる。
【００６２】
さらにこれらの構成により、撹拌槽１中心付近の撹拌中の液面において、撹拌軸２を中心とした適度なボルテックスを発生せしめ、固体粒子を含む液体は途中で停滞することなく、撹拌槽１内を一筆書き状に円滑に循環することになることにより、撹拌槽１内全体を均一に混合する時間を短縮でき、混合特性を向上できる。
【００６３】
また、液体中の固体粒子の比重と液体の比重との比率（固体の比重／液体の比重）が０．７〜１．０の場合においては、固体粒子を含む液体は、比重差から生じる浮力に対抗して撹拌槽内全体を一筆書き状に更に円滑に循環することが可能である。
【００６４】
本発明の撹拌装置１０（図１〜３）の翼の動力性能を表すものとしてNp-Re線図を図９に示す。同図中Npは翼による液の動力性能を示す指標で、動力数と言われ、P/ρ・n³・d⁵で表される。ここで、P:動力（Ｗ）、ρ：液密度（kg/m³）、n：翼回転数（1/sec）、d：パドル翼長（m）を示す。
【００６５】
静止液深H=0.29m、槽径D=0.29m、パドル翼長ｄ＝0.155m、中段櫛状翼長ｄ_１＝0.0775ｍ、中段櫛状翼高さｈ_１＝0.11ｍ、上段撹拌翼長ｄ_２＝0.0465ｍ、上段櫛状翼高さｈ_２＝0.11ｍとした。液量16.97Lとした。静止液面と上段撹拌翼の上端との間の距離が、静止液深の３％とした。
【００６６】
水のみを含む場合、ポリプロピレン粒子（比重0.91）を粒子１：水２（重量比）で含む場合、粒子１：水１（重量比）で含む場合について調べた。液密度は、ポリプロピレン粒子の含有量に応じて、水のみの場合1000、粒子１：水２の場合966、粒子１：水１の場合952として計算した。ポリプロピレン粒子の形状は、楕円柱状であり、長さ2.6mm〜3.2mm、楕円断面の長径1.0mm〜1.3mm、短径0.7mm〜0.9mmのものを用いた。
【００６７】
図９は、流体として水のみを含む場合の、本発明の撹拌装置における撹拌レイノルズ数(Re)と動力数(Np)の関係を示したものである。
【００６８】
邪魔板については図１記載のようなギャップ比（ｄｇ／Ｄ）が4.8%の邪魔板２枚の場合に加え、幅比4.8%の邪魔板３枚を１２０度間隔で設置した場合、幅比7.9%の邪魔板を１２０度間隔で３枚設置した場合、幅比9.0%の邪魔板を９０度間隔で４枚設置した場合も示した。
【００６９】
Reが40000〜100000の領域で、Np値はほぼ一定であり、平均すると、槽径Ｄの４．８％幅の邪魔板２枚の場合2.48（以下「邪魔板4.8%×２枚の場合」等という。）、邪魔板4.8%×３枚の場合3.36、邪魔板7.9%×３枚の場合4.62、邪魔板9.0%×４枚の場合5.07となった。同様に、粒子１：水２の場合および粒子１：水１の場合を比較例とあわせて表１に示す。
【００７０】
【表１】

【００７１】
図４には、従来の撹拌装置の一例として、特開平１０−２４２３０記載の撹拌装置のうち、櫛状の翼２４と２５が全く同じ形状である撹拌装置Ａを示した。この撹拌装置Ａでは、最上部の櫛状の翼形状を除き、本発明の撹拌装置と同じ形状の特徴を有する。
【００７２】
図５、６には、層流域から乱流域まで幅広く利用できる従来の撹拌装置の例として、撹拌槽底部内面に下端部を摺接させたパドル翼と、これに連接した格子状翼および撹拌槽壁内面に軸方向に延在した邪魔板を設けた撹拌装置Ｂを示した(特開平６−３１２１２２参照)。ここで、撹拌槽３１内中心部には撹拌軸３２が配設されている。符号は下部がパドル翼、上部がそれに連続して設けられた格子状翼からなる大型翼である。本実施例では、本発明の装置と同様、邪魔板３６を設置した。
【００７３】
図７、８には、全体混合を良くするための翼として用いられる、Ｈ型翼を用いた従来の撹拌装置Ｃを示した。
【００７４】
図１０には、撹拌装置Ａ、撹拌装置Ｂおよび撹拌装置Ｃにおいて、上述の本発明の撹拌装置によるNp-Re線図を求める際に採用した条件を用いた場合のNp-Re線図を示した。
【００７５】
撹拌装置Ａ、Ｂでは、Reが40000〜100000の領域でNp値はほぼ一定であり、流体として水のみを含む場合、平均すると、撹拌装置Ａの邪魔板4.8%×２枚の場合2.48、邪魔板9.0%×４枚の場合4.95、撹拌装置Ｂの邪魔板4.8%×２枚の場合2.49、邪魔板9.0%×４枚の場合5.09、となった。
【００７６】
表１に示すように、Ｎｐの値で比較した場合の撹拌効率としては、撹拌装置Ａおよび撹拌装置Ｂと同程度であり、また、これらは撹拌装置Ｃを上回っている。撹拌装置Ｃは、他の翼に比べ効率が悪いことがわかる。
【００７７】
また、ポリプロピレン粒子（比重0.91）を粒子１：水２（重量比）で含む場合、粒子１：水１（重量比）で含む場合についても、撹拌効率をＮｐ値で比較すると、本実施例に係る撹拌装置と、撹拌装置Ａおよび撹拌装置Ｂは略同程度であり、かつ、撹拌装置Ｃを上回っていることがわかる（表１）。
【００７８】
（実施例１）
図１に示す本発明の撹拌装置１０を用いて、上述の本発明の撹拌装置によるNp-Re線図を求める際に採用した条件（但し、以下に記す条件を除いては）で、ポリプロピレン粒子１：水２(重量比)の場合の混合状態の観察結果、流動状態及び混合液の混合状態の判定結果を表２に示す。
【００７９】
【表２】

【００８０】
ここで、邪魔板は幅比4.8%×２枚の場合であり、ポリプロピレン粒子の形状は、楕円柱状で、長さ2.6mm〜3.2mm、楕円断面の長径1.0mm〜1.3mm、短径0.7mm〜0.9mmのものを用いた。
【００８１】
本発明の装置では、撹拌回転数が150rpm以上(単位体積あたりの動力が0.227 kW/m³以上)において、上下循環流が生じ、全体に良好な混合状態が得られた。また、撹拌回転数が250rpm(単位体積あたりの動力が1.058 kW/m³)となっても、液面近傍の粒子が飛散することはなく、上下混合はますます良好になった。
【００８２】
一方、撹拌装置ＡおよびＢでは、撹拌回転数が150rpmでは全体に流動しているものの、表面近傍では回転方向の流れが強く、本発明の撹拌装置に比べ、混合性能はやや悪い。また、撹拌回転数を上げるに従い、回転方向の流れは強まっていく。これは、液面近傍の撹拌翼の翼長が、下部の撹拌翼の翼長と同じであるため、下部パドル翼から押し出され、槽壁面を上昇してきた粒子が、上部格子状または櫛状翼の吐出流にさえぎられてしまっているためと考えられる。
【００８３】
一方、本発明の装置では、最上段櫛状翼の翼長ｄ_２（図１）を、下部の櫛状翼よりも短い構成にしているため、壁面を上昇してきた流れがスムーズに液面まで達し、液面に達した粒子は、槽中央部に生じたボルテックスにより、撹拌軸に沿って槽底部まで吸い込まれるという効果がある。このボルテックスについても、幅広の櫛状の翼では、大きくなり過ぎるため、流れを半径方向に押し、邪魔板近傍での粒子の停滞を引き起こし、スムーズな吸い込みには寄与しない。
【００８４】
撹拌装置Ｃでは、槽高さ１／２付近での吐出流が上下に分かれて下半分と上半分に分離した流れができる。また、回転方向の流れが強く、上下混合はきわめて悪くなる。また、翼面積が広いため、粒子を押しのける力が強くなり、撹拌回転数を上げると固体粒子が激しく飛散してしまう現象も起こる。
【００８５】
同様に、邪魔板4.8%×２枚の場合について、ポリプロピレン粒子１：水１．５の場合を表３に、ポリプロピレン粒子１：水１の場合を表４に示した。
【００８６】
【表３】

【００８７】
【表４】

【００８８】
固体粒子の比率が高くなるにつれ、邪魔板の回転方向手前側での停滞が目立つようになる。また、撹拌装置Ａ、Ｂなどの翼長が下部パドル翼と同じ場合、特に上部の流動性が悪くなってくるため、全体の混合性も悪化する。
【００８９】
しかしながら、本発明の撹拌装置では、上昇流がスムーズに液面付近にまで達し、若干の邪魔板近傍での停滞があるものの、全体混合を妨げるほどではない。粒子１：水１の場合でも、撹拌回転数が150rpm以上(単位体積あたりの動力が0.363 kW/m³以上)あれば、混合性は良好であった。
【００９０】
（実施例２）
実施例１に用いた混合装置１０を用い、固体粒子を除いては実施例１と同様の条件で、ポリエチレンテレフタレート（ＰＥＴ）粒子（比重１．３８）１：水２(重量比)の場合の混合性の判定結果を略同形状のポリプロピレン（ＰＰ）粒子を用いた場合と対比して表５に示す。
【００９１】
【表５】

【００９２】
ここで、邪魔板は幅比4.8%×２枚の場合であり、ポリエチレンテレフタレート粒子の形状は、楕円柱状で、長さ2.6mm〜3.2mm、楕円断面の長径1.0mm〜1.3mm、短径0.7mm〜0.9mmのものを用いた。
【００９３】
（実施例３）
実施例１に用いた混合装置１０を用い、固体粒子を除いては実施例１と同様の条件で、球状ポリプロピレン粒子１：水２(重量比)の場合の混合性の判定結果を、ペレット状のポリプロピレン粒子の場合と対比して表６に示す。
【００９４】
【表６】

【００９５】
ここで、邪魔板は幅比4.8%×２枚の場合であり、ポリプロピレン粒子の形状は、球状で、直径2.0mm〜2.2mmのものを用いた。固体粒子が球状であっても、ペレット状の場合と同様良好な混合性を示した。
【００９６】
（実施例４）
実施例２に用いた撹拌装置を用いて、傾き角βを除いては実施例１と同じ条件で、傾き角βを変えた場合の混合性の判定結果を表７に示す。
【００９７】
【表７】

【００９８】
ここで、邪魔板は幅比4.8%×２枚の場合である。
【００９９】
（実施例５）
実施例２に用いた撹拌装置を用いて、高さ比ｈ／Ｈを除いては実施例１と同じ条件で、高さ比ｈ／Ｈを変えた場合の混合性の判定結果を表８に示す。
【０１００】
【表８】

【０１０１】
ここで、邪魔板は幅比4.8%×２枚の場合である。
【０１０２】
（実施例６）
実施例２に用いた撹拌装置を用いて、固体粒子と液体の配合比を除いては実施例１と同じ条件で、固体粒子と液体の配合比を変えた場合の混合性の判定結果を表９に示す。
【０１０３】
【表９】

【０１０４】
ここで、邪魔板は幅比4.8%×２枚の場合である。
【０１０５】
（実施例７）
ヨードとハイポ反応による着脱色を行い、撹拌槽内の混合時間を調べた。実施例１と同様の装置を用い、ポリプロピレン粒子１：水１．５の場合の脱色時間を測定したところ、表１０のようになった。
【０１０６】
【表１０】

【０１０７】
ここで、邪魔板は幅比が4.8%×２枚の場合であり、ポリプロピレン粒子の形状は、楕円柱状で、長さ2.6mm〜3.2mm、楕円断面の長径1.0mm〜1.3mm、短径0.7mm〜0.9mmのものを用いた。
【０１０８】
撹拌所要動力がほぼ等しい撹拌回転数で本発明の撹拌装置と撹拌装置Ｃの脱色時間を比較すると、本発明の方が半分の時間となっており、多量の粒子を含んでいる場合でも、液の混合性能がきわめて良いことを示している。
【０１０９】
【発明の効果】
本発明は、以上の構成により、次に示す効果を奏するものである。
液体中の粒子濃度が１５〜４２vol%程度であるような粒子が高濃度に分散している場合においても、撹拌槽内には軸方向の大きな循環流が発生し、槽内には停滞部が少なく、撹拌中の液面上部の空中へ固体粒子が飛散しない状況を作り出せる。これらのことにより、撹拌槽内における混合が良好に進行することや、撹拌槽内における液体と固体間の物質移動と熱移動及び反応が良好に進むこと、及び液面を介して液体と気相部の間においても良好な物質移動が期待できる。
【図面の簡単な説明】
【図１】本発明の撹拌装置の略示斜視図
【図２】本発明の撹拌装置の略示縦断側面図
【図３】本発明の撹拌装置の略示横断平面図
【図４】特開平１０−０２４２３０の撹拌翼（撹拌装置Ａ）の略示斜視図
【図５】特開平６−３１２１２２の撹拌翼（撹拌装置Ｂ）の略示斜視図
【図６】特開平６−３１２１２２の撹拌翼（撹拌装置Ｂ）の略示縦断側面図
【図７】Ｈ型の撹拌翼（撹拌装置Ｃ）の略示斜視図
【図８】Ｈ型の撹拌翼（撹拌装置Ｃ）の略示縦断側面図
【図９】本発明の撹拌翼を用いた場合のNp-Re線図
【図１０】撹拌装置Ａ，Ｂ，Ｃを用いた場合のNp-Re線図
【符号の説明】
１：撹拌槽
２：撹拌軸
３：パドル翼
３ａ、３ｂ：幅広撹拌翼
４ａ、４ｂ：中段櫛状翼
５ａ、５ｂ：上段櫛状翼
６：邪魔板
７：撹拌槽の内壁面
８：皿型鏡版
９：パドル翼の下側の縁部
１０：本発明に係る撹拌装置
２０：特開平１０-２４２３０に開示の撹拌装置Ａ
３０：一枚ゲート型撹拌装置Ｂ
３１：撹拌槽
３２：撹拌軸
３６：邪魔板
４０：Ｈ型撹拌装置
４７：Ｈ型撹拌翼[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wide range of stirring in a laminar flow region to a turbulent flow region, and in particular, solid-liquid system mixing, solid-liquid system reaction, solid-liquid system mass transfer, solid-liquid system heat transfer, gas-liquid- Solid reaction, gas-liquid-solid mass transfer, gas-liquid-solid heat transfer, crystallization, immobilized enzyme reaction, immobilization of cells on carrier, mixing of high concentration slurry and The present invention relates to an agitation apparatus and an agitation method for efficiently performing a reaction and the like.
[0002]
[Prior art]
In order to stir and mix substances of two or more phases having a specific gravity difference, it is particularly necessary to generate a strong flow in the vertical direction. For this purpose, various types of stirring blades are used. However, it becomes difficult to effectively perform mixing as the ratio between the height and the diameter of the stirring tank increases.
[0003]
When one or more small turbine blades or H-shaped blades are installed, the discharge flow in the radial direction is strong, and the flow in the tank is separated at the center of the height in the axial direction of the agitation tank. Become. Moreover, since local shear force becomes strong, it is not suitable when fragile solid particles such as immobilized enzyme are used in the reaction.
[0004]
By using inclined turbine blades, propeller blades, inclined paddle blades, etc., it is possible to generate axial flow in the vertical direction. However, these agitating blades require a higher shearing speed, so local shearing force is applied. In addition, since the axial flow is strongly generated only in the vicinity of the blades and it is difficult to uniformly mix the entire tank, it has the same problem as when the turbine blades are used.
[0005]
Also,
Journal of Chemical Engineering of Japan, Vol. 32, no. P. 40-44, 1999, KOJI TAKAHASHI and SHIN-ICHIRO SASAKI; “Completed Drawdown and Dispersion of Floating Solids in Agitated Vessel” Although stirring conditions for mixing the particles are discussed, this prior art limits the volume concentration of solid particles to a maximum of about 10.3 vol%.
[0006]
On the other hand, in the case of a large paddle blade used for stirring a highly viscous fluid, when a low viscosity fluid containing a large amount of solid particles is mixed, the power consumed for stirring becomes very large and the operation cost becomes a problem. Further, in the double helical ribbon blade, these fluids rotate together with the stirring blade, and mixing is not promoted.
[0007]
For example, in the past, development of a stirring device aimed at the entire mixing in a stirring tank in a wide range of viscosity has been promoted, as disclosed in JP-A-8-24609, JP-A-5-49890, and JP-A-9-75699. In JP-A-8-71398, JP-A-7-124456, etc., a stirring blade in which various paddle blades are arranged in multiple stages is used. However, when the fluid contains a lot of solid particles, if the stirring blades composed of multistage paddle blades arranged above and below are used, the discharge flow from each stirring blade interferes and the axial circulation in the tank is greatly hindered, which is not always appropriate. Stirring operation cannot be performed.
[0008]
In addition, in the stirrers disclosed in Japanese Patent Laid-Open Nos. 9-108557 and 10-24230, the one in which the lattice blades are arranged on the top of the bottom paddle has been proposed, but it is not effective for a fluid containing solid particles. In some cases, particularly when there is a belt-like member extending in the radial direction from the stirring shaft, that portion forms a discharge flow like the paddle blade, which also hinders the vertical flow.
[0009]
Furthermore, Japanese Patent Application Laid-Open No. 2000-210549 proposes an apparatus for preventing solid particles from stagnation. However, in the prior art, the specific gravity of solid particles is heavy, and the case where the solid particles stagnate is assumed.
[0010]
[Problems to be solved by the invention]
In this way, in order to mix the two phases of solid and liquid as uniformly as possible, the flow in the vertical direction is generated while suppressing the generation of local shearing force. It must be strong enough to overcome the buoyancy or gravity of the particles. In particular, when mixing a fluid containing a large amount of solid particles, it is necessary to prevent the stagnation of these particles from occurring. The present invention intends to provide a stirring device and a stirring method for realizing such a flow and uniformly mixing a mixed liquid of solid particles and a liquid.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the gist of the stirring device of the present invention is as follows:
An agitation tank containing a mixture of solid particles and liquid;
An agitation shaft disposed substantially perpendicular to the stationary liquid surface of the mixed liquid in the agitation tank;
A wide stirring blade supported at the lowermost stage of the stirring shaft;
A plurality of comb-shaped blades that are sequentially arranged in a step shape above the wide stirring blade and are respectively supported by the stirring shaft;
Including
The wide stirring blade is located at the bottom of the stirring tank,
The middle stage comb-shaped blade, which is a comb-shaped blade adjacent to the wide stirring blade, is disposed in front of the wide stirring blade at an angle of less than 90 degrees with respect to the rotation direction of the stirring shaft, and the axial direction of the stirring shaft Having an overlap with the wide stirring blade,
The upper comb-like wings, which are comb-like wings other than the middle-stage comb-like wings, are disposed in front of the lower adjacent comb-like wings at an angle of less than 90 degrees in the rotation direction of the stirring shaft, and the stirring shaft Having an overlap with the adjacent comb-shaped wing in the axial direction of
The blade length of each upper comb-like wing is shorter than the blade length of the comb-like wing adjacent below,
When stirring is stopped, a part of the uppermost comb-like blade is a stirring device in which the liquid mixture does not protrude from the stationary liquid surface.
[0012]
The upper comb-like wing may have one stage.
[0013]
The blade length of each comb-shaped wing may be 0.5 to 0.9 times the blade length of the comb-shaped wing adjacent below.
[0014]
In the stirring device, the distance between the static liquid level and the upper end of the uppermost comb-shaped wing may be 0 to 5% of the static liquid depth of the mixed liquid.
[0015]
In the stirring device, the direction from the stirring shaft toward the tip of the middle comb-shaped blade along the length of the middle comb-shaped blade is 5 or 5 above or below the direction perpendicular to the stirring shaft. With a constant slope between 75 degrees,
The direction from the stirring shaft toward the tip of each upper comb blade along the length of each upper comb blade may have the constant inclination with respect to the direction perpendicular to the stirring shaft.
[0016]
The constant slope may be 25 to 35 degrees up or down.
[0017]
In the stirring device, a plurality of baffle plates may be mounted in the vertical direction on the wall in the stirring tank.
[0018]
In the stirring device, the degree of overlap with respect to the axial height from the lower end of the wide stirring blade to the upper end of the uppermost comb blade of the middle comb blade and the wide stirring blade is 2.5 to It can be 5%.
[0019]
In the stirring device, the degree of overlap with respect to the axial height from the lower end of the wide stirring blade to the upper end of the uppermost comb blade of each of the comb blades and the lower adjacent comb blade is 2 It may be 5-5%.
[0020]
In addition, the gist of the present invention is that
Put the mixed liquid of solid particles and liquid into a stirring tank,
Rotating a stirring shaft disposed in the stirring tank to stir the mixed solution to form a vortex centered on the stirring shaft,
Creating a downward flow along the liquid surface of the mixture in which the vortex is formed;
Reversing the descending flow at the bottom of the agitation tank and ascending the flow along the inner wall of the agitation tank,
Inverted again at the top of the mixture to circulate
It is that it is the stirring method of the liquid mixture characterized by this.
[0021]
In the stirring method of the mixed solution, any of the stirring devices described above can be used.
[0022]
In the stirring method of the mixed liquid, the specific gravity of the solid particles may be smaller than the specific gravity of the liquid.
[0023]
In the method of stirring the mixed solution, the solid particles may be a pellet-shaped resin.
[0024]
In the stirring method of the mixed solution, the volume concentration of the solid particles in the mixed solution may be 15 to 42 vol.%.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic view showing a basic configuration of a stirring device 10 of the present invention. A stirring shaft 2 is disposed at the center of the stirring tank 1. Reference numeral 3 denotes a two-paddle blade (hereinafter referred to as a paddle blade) composed of two

wide stirring blades

3 a and 3 b, and is attached to the lower end portion of the stirring shaft 2. Reference numerals 4a and 4b denote a middle comb-like wing adjacent to the paddle wing 3 located at the lowermost stage.

Reference numerals

5a and 5b denote upper comb-like wings located at the uppermost stage.
[0026]
The middle comb-like blade 4a is disposed at an angle of 45 degrees with respect to the wide stirring blade 3a in advance with respect to the rotation direction, and the wide stirring blade 3a is an upper comb-like blade from the lower end of the wide stirring blade 3a. An overlap Δh of 4.4% of the axial height h to the upper ends of 5a and 5b ₁ (Δh in FIG. ₁ /H=0.044). In the present specification, the ratio of the overlap Δh between one blade and another blade to the height h in the axial direction from the lower end of the wide stirring blade 3a to the upper ends of the

upper comb blades

5a and 5b is expressed in%. The value obtained is defined as the degree of overlap.
[0027]
The upper comb-like wing 5a is disposed ahead of the rotation direction at an angle of 45 degrees with respect to the middle-stage comb-like wing 4a, and the middle-stage comb-like wing 4a has a length of 4.4% of h. Overlap Δh ₂ (Δh in FIG. ₂ /H=0.044). Further, the shape of the upper comb-

like wings

5a and 5b is different from that of the middle-stage comb-like wings 4a and 4b, except for the combs outside the middle-stage comb-like wings 4a and 4b, and the upper-stage comb-like wings 5a. 5b horizontal wing length d ₂ Is the horizontal blade length d of the middle comb-like blades 4a, 4b. ₁ 60% of (d ₂ / D ₁ = 0.6; FIG. 2). In the present specification, the blade lengths of the wide stirring blades and comb blades are the blade lengths in the horizontal direction as shown in FIG.
[0028]
Two baffle plates 6 having a width of 4.8% of the tank diameter D are arranged at a position of 180 degrees in the circumferential direction of the tank. The baffle plate 6 and the tank inner wall surface 7 are provided with a gap dg of 5% of the tank diameter D. The bottom is a plate-shaped end plate 8, and the lower edge 9 of the paddle blade 3 is kept at a constant interval w from the plate-type end plate 8. The interval w is 1.8% of h. (W / h = 0.018 in FIG. 2).
[0029]
The number of baffle plates 6, the gap dg with the inner wall 7, and the interval w between the paddle blade 3 and the dish-shaped end plate 8 may be changed depending on the size of the tank, the size, amount, specific gravity, etc. of the particles to be introduced. . Further, the effect of the present invention can be exhibited when the dish-type end plate 8 is a flat type, a semispherical surface type, a semispherical surface type, or a semispherical ellipsoidal surface type in addition to the plate shape.
[0030]
FIG. 3 is a cross-sectional view of the stirring device 10 according to the present invention. As the stirring tank 1 used for this invention, the stirring shaft 2 which can be rotationally driven from the outside of a tank can be installed and used in a tank.
[0031]
Examples of the shape of the stirring tank 1 include a cylindrical shape, a conical shape, a cylindrical shape having an elliptical cross section, and the like, but a cylindrical shape is preferable for obtaining good mixing and flow. Moreover, it is preferable that the bottom part of a tank consists of a concave mirror-shaped end plate convex downward from a liquid circulation and fluidity | liquidity.
[0032]
The materials of the stirring tank 1, the paddle blade 3, the middle comb-like blades 4a and 4b, and the

upper stirring blades

5a and 5b are not particularly limited, but are austenitic or ferrite considering the strength, heat resistance and corrosion resistance of the materials. Austenitic stainless steel is preferable, and is appropriately selected depending on the liquid used. For economic reasons, austenitic stainless steels such as SUS304, SUS316, and SUS316L are particularly preferable.
[0033]
The stirring shaft 2 is disposed substantially perpendicular to the static liquid level. Although it may be installed at any position in the tank, it is preferably installed vertically in the center of the tank for the reason of obtaining good mixing and flow.
[0034]
The paddle blade 3 composed of the

wide stirring blades

3a and 3b is installed at the bottom of the stirring tank 1, the lower part is close to the bottom of the tank, and the liquid depth at rest of the vertical width ho of the

wide stirring blades

3a and 3b ( The ratio ho / H with respect to the still liquid depth H is preferably 0.25 or more, more preferably 0.3 or more, in order to obtain a good stirring state. The ratio d / D of the blade length d of the paddle blade 3 to the tank diameter D is preferably 0.35 or more, more preferably 0.45 or more, in order to obtain a good stirring state. The upper limit of ho / H is such a height that the discharge flow to the paddle blade does not immediately return to the upper portion of the paddle blade, and the upper limit of d / D is to contact the stirring tank 1 and the baffle plate 6 and other equipment. There is no size (FIG. 2).
[0035]
Further, as the paddle blade 3, a conventionally known flat plate can be used almost without limitation, and the paddle blade 3 may have a wavy structure.
[0036]
Furthermore, the height ratio h / H with respect to the static liquid depth H of the total height h of the entire stirring blade composed of the paddle blade 3, the intermediate comb blades 4a and 4b, and the

upper stirring blades

5a and 5b obtains a good stirring state. In addition, it is 0.7 or more and less than 1.0, and more preferably 0.94 to 0.96.
[0037]
In particular, when the height ratio h / H is 0.94 to 0.96, a vortex (vortex) is formed near the liquid surface around the stirring shaft 2 to promote the entrainment of fluid containing solid particles. Is advantageous.
[0038]
Here, the vortex means that the liquid in the tank rotates due to the rotation of the stirring blade, and as a result, the dynamic pressure near the center of the tank decreases, and the liquid surface near the center of the stirring tank dents toward the bottom of the tank. To tell.
[0039]
When the height ratio is less than 0.7, the distance between the liquid surface and the upper ends of the

upper stirring blades

5a and 5b is increased, the streamlines in the tank are not in a single stroke state, and a plurality of vortices are vertically arranged. Tends to exist, and tends to lower the mixing performance in the tank. Further, in the vicinity of the liquid surface where the

upper stirring blades

5a and 5b do not scan, the circulation flow of the liquid becomes slow, and a stagnant portion is likely to occur, resulting in poor mixing efficiency.
[0040]
On the other hand, when the height ratio is 1.0 or more, the solid particles near the liquid surface are scattered in the radial direction as the

upper stirring blades

5a and 5b rotate. Therefore, even if the discharge flow generated by the paddle blades 3 arranged at the bottom of the tank is converted into an upward flow by the baffle plate 6, the upward flow and the scattered solid particles collide with each other in the stirring tank 1. Make the flow worse.
[0041]
The entire stirring blade in the present invention has a paddle blade 3 made of a wide flat plate arranged at the bottom of the stirring tank 1 at the bottom, and a plurality of comb-shaped blades (middle comb-shaped blades 4a, 4b,

upper stirring blades

5a, 5b, etc.). Any number of the comb-shaped wings may be provided, but a case where two comb-shaped wings are arranged will be described.
[0042]
Above the paddle blade 3 composed of a wide flat plate disposed at the lowermost stage, the middle comb-shaped blades 4a and 4b and the

upper stirring blades

5a and 5b are disposed. Here, as shown in FIG. 3, the middle comb-like wing adjacent to the uppermost paddle wing is disposed ahead of the paddle wing 3 with respect to the rotational direction at an angle α of less than 90 degrees. Preferably, this angle is set to 40 to 50 degrees so as to reduce the degree of interference of the discharge flow of the blades of each stage and to reduce the force that causes the stirring shaft 2 to be eccentric. In FIG. 3, the angle α is 45 degrees.
[0043]
The middle comb-like wings 4a and 4b are arranged so that their longitudinal directions are included in one plane. The upper comb-

like wings

5a and 5b are also arranged so that each longitudinal direction is included in one plane. A plane including the longitudinal direction of the middle comb-like wing 4a and a plane including the longitudinal direction of the middle-stage comb-like wing 4b may form a predetermined angle. Further, three or more intermediate comb-like wings may be provided. The plane including the longitudinal direction of the upper comb-like wing 5a and the plane including the longitudinal direction of the upper comb-like wing 5b may form a predetermined angle. Three or more upper comb-like wings may be provided. The wide agitating

blades

3a and 3b are also arranged so that each longitudinal direction is included in one plane. The plane including the longitudinal direction of the wide stirring blade 3a and the plane including the longitudinal direction of the wide stirring blade 3b may form a predetermined angle. Three or more wide stirring blades may be provided to form a paddle blade composed of a large number of wide stirring blades.
[0044]
Further, the paddle blades and the middle comb-like blades 4a and 4b have an overlap in the stirring axis direction. Preferably, this overlap Δh is used so that the discharge flow from each stage blade does not become an isolated local vortex. ₁ Ratio of h (the axial height from the lower end of the wide stirring blade 3a to the upper ends of the

upper comb blades

5a and 5b) (degree of overlap) Δh ₁ / H is preferably 2.5% or more. More preferably, it is 3 to 5%.
[0045]
Similarly, the upper comb-like wing 5a adjacent on the middle-stage comb-like wing 4a is arranged to precede the middle-stage comb-like wing 4a in the rotational direction and overlap with the stirring shaft 2 direction. This overlap Δh ₂ Ratio of h to h (overlapping degree) Δh ₂ / H is preferably 2.5% or more in order to prevent the discharge flow from the blades of each stage from becoming isolated local vortices. More preferably, it is 3 to 5%.
[0046]
The upper comb-like wing 5b adjacent to the middle-stage comb-like wing 4b precedes the middle-stage comb-like wing 4b in the rotation direction, and is arranged so as to overlap the stirring shaft 2 direction.
[0047]
The middle comb-like blades 4a and 4b may have the same or different blade lengths as the

wide stirring blades

3a and 3b. However, as shown in FIG. Ratio d of comb-like wings 4a, 4b to wing length ₂ / D ₁ Is preferably 0.5 to 0.9. More preferably, it is 0.55-0.65.
[0048]
Further, even if the number of comb teeth of the middle comb-like wings 4a and 4b is equal to the number of comb teeth of the upper-stage comb-

like wings

5a and 5b, the number of comb teeth of the upper-stage comb-

like wings

5a and 5b. However, it may be less than the number of comb teeth of the middle comb-like wings 4a, 4b. The longitudinal directions of the middle comb-like blades 4a and 4b and the upper comb-

like blades

5a and 5b are not perpendicular to the stirring shaft 2, but have an inclination with respect to the direction perpendicular to the stirring shaft 2 as shown in FIG. It is good also as a structure to allow. Preferably, the inclination angle β is 5 to 75 degrees up or down, and more preferably, this angle is up or down in order to achieve a structure in which the discharge flow by this member is not noticeable and easy to manufacture. Below 25-35 degrees is good. In FIG. 2, the inclination angle β is 30 degrees.
[0049]
Further, a baffle plate 6 may be disposed on the side wall surface 7 of the stirring tank 1 so as to continuously extend in the direction of the stirring shaft 2 from the bottom of the stirring tank 1 to the position of the stationary liquid surface. The baffle plate 6 is preferable because it has the effect of changing the flow discharged from the paddle blade 3 into an upward flow.
[0050]
The shape of the baffle plate is not particularly limited as long as it does not contact the wing. However, for example, a flat plate type or an inclined type as disclosed in JP-A-09-052037 may be used, and a plurality of baffle plates may be installed. Preferably, when a large amount of solid particles is included, a liquid stagnation portion is likely to occur on the back surface of the baffle plate.
[0051]
Further, the width d of the baffle plate 6 at this time ^' Is 3% to 10% with respect to the tank diameter D (FIG. 2). This width d ^' Is a width that can suitably convert the discharge flow from the paddle blade 3 arranged at the bottom of the tank into an upward flow, and when a large amount of solid particles is contained, a liquid stagnation portion does not occur on the back surface of the baffle plate 6. About 4-6% is still more preferable with respect to the tank diameter D.
[0052]
The stirrer according to the present invention is suitably used for the purpose of uniformly mixing a mixed liquid of solid particles and liquid. The liquid used in the present invention is not particularly limited, but is a low-viscosity inorganic solvent typified by water, and when the solid particles are not made of a synthetic resin, or the solid particles made of a synthetic resin are easily dissolved in an organic solvent. If not or insoluble, organic solvents (hydrocarbons, halogenated hydrocarbons, alcohols, phenols, ethers, acetals, ketones, fatty acids, acid anhydrides, esters, nitrogen compounds) , Sulfur compounds, compounds having two or more functional groups).
[0053]
Although it does not specifically limit as solid particles used by this invention, It is a product made from a synthetic resin, for example, vinyl resin (polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol), fluororesin (tetrafluoroethylene) Polytetrafluoroethylene, hexafluoropropylene, tetrafluoroethylene perfluoroalco comb ethylene copolymer, tetrafluoroethylene ethylene copolymer, trifluoroethylene chloride, vinylidene fluoride), polystyrene resin (polystyrene, styrene)・ Acrylic nitrile / butadiene copolymer), polyethylene resin (low density polyethylene, high density polyethylene, ethylene / vinyl acetate copolymer), polyamide (6 nylon, 11-nylon), polyacetal, polyphenylene oxide, polycarbonate, polypropylene , Poly --Methyldenten, polymethyl methacrylate, cellulose acetate, ionomer, polyurethane, polyester elastomer, polyertel, rubber (ethylene / propylene rubber, chloroprene rubber, chlorosulfonated polyethylene, nitrile rubber, acrylic rubber, isoprene rubber, styrene / butadiene rubber, Butyl rubber, epichlorohydrin rubber, urethane rubber, multi-flow rubber, silicone rubber, fluorine rubber, natural rubber) and the like.
[0054]
Examples of the shape of the solid particles include a sphere, an ellipsoid, a disk, a cylinder, a tetrahedron, a hexahedron, an octahedron, a dodecahedron, and an irregular shape, and are not limited thereto. Although it is not limited to the shape, it is preferably a pellet shape (columnar shape) and the fractional ratio of the minor axis to the major axis is 1/5 to 5. When this fractional ratio is smaller than 1/5 or larger than 5, solid particles are entangled in the liquid, exhibiting a behavior as a non-Newtonian fluid, and the flow in the tank becomes unsmooth.
[0055]
Moreover, as a dimension of a solid particle, the major axis is 0.5-20 mm, Preferably it is 1-4 mm. Furthermore, the specific gravity of the solid particles is 0.5 to 2.5 times the specific gravity of the liquid. In order to smoothly flow against the gravity or buoyancy due to the difference in specific gravity with the liquid, the specific gravity of the solid particles is particularly The preferred range is 0.7 to 1.3 times the specific gravity of the liquid, more preferably 0.7 to 1.0 times.
[0056]
Even if the volume concentration of these solid particles is in the range of 1 to 42 vol%, the stirrer blades of the present invention can be used to smoothly flow without stagnant portions. In particular, the stirring device of the present invention is more effective when the volume concentration of solid particles is in the concentration range of 15 to 42 vol%. As described above, in the stirring by the conventional stirring device, stirring is performed well when the volume concentration of the solid particles is less than 10.3 vol%, but in the present invention, stirring is performed well even in the concentration range of 15 to 42 vol%. It is.
[0057]
In order to mix the two phases of solid and liquid as uniformly as possible by the above method, the flow in the vertical direction is generated while suppressing the generation of local shearing force. The strength required to overcome the buoyancy or gravity of the particles due to the difference is required. In particular, even when a fluid containing a large amount of solid particles is mixed, it is necessary not to generate a stagnant portion of these fluids.
[0058]
With the stirring device 10 according to the present invention having the above-described configuration, even a liquid containing a large amount of solid particles is discharged by the paddle blade 3 formed of a wide flat plate disposed near the bottom wall surface of the stirring tank 1. The liquid collides with the inner wall of the stirring tank 1 and the baffle plate 6 and rises. At this time, the comb-shaped wings of the intermediate comb-shaped wings 4a and 4b adjacent on the paddle wing 3 are disposed in advance in the rotational direction at an angle of less than 90 degrees with respect to the paddle wing 3, and the paddle Since the blade 3 and the intermediate comb-shaped blades 4a and 4b overlap in the direction of the stirring shaft 2, the liquid discharged from the middle-stage comb-shaped blades 4a and 4b does not hinder the rise of the liquid discharged from the paddle blade. .
[0059]
Further, by making the middle stage comb-like blades 4a, 4b out of the whole stirring blade, the flow discharged from the middle stage comb-like blades 4a, 4b is reduced. That is, in the agitated portion of the intermediate height of the tank, the flow discharged from the lower paddle blade 3 and the flow generated by the discharge from the middle comb blades 4a and 4b interfere with each other to cancel the flow. There is no such thing.
[0060]
The upper upper comb-

like wings

5a and 5b are also arranged to precede the rotational direction at an angle of less than 90 degrees with respect to the middle-stage comb-like wings 4a and 4b, and have an overlap in the direction of the stirring shaft 2. Further, by setting the blade length of the

upper comb blades

5a and 5b to about 60% of the blade length of the middle comb blades 4a and 4b, the liquid rising along the inner wall of the agitation tank is discharged from the uppermost stage. The collision with the liquid is prevented, and the liquid is not stagnated in the vicinity of the liquid surface and in the vicinity of the baffle plate 6.
[0061]
Further, a position where the blade length of the

upper comb blades

5a and 5b is shortened and the blades of the

upper comb blades

5a and 5b are submerged from the stationary liquid surface by a height of 0 to 5% of the stationary liquid depth. By disposing in this manner, the scattering of solid particles in the liquid into the air above the liquid surface being stirred can be significantly suppressed. Therefore, the kinetic energy transmitted by the stirring blade can be efficiently transmitted to the liquid.
[0062]
Furthermore, with these configurations, an appropriate vortex around the stirring shaft 2 is generated at the liquid level in the vicinity of the stirring tank 1 near the center, and the liquid containing solid particles does not stagnate in the middle of the stirring tank 1. Is smoothly circulated in a single stroke, the time for uniformly mixing the entire inside of the stirring tank 1 can be shortened, and the mixing characteristics can be improved.
[0063]
When the ratio of the specific gravity of the solid particles in the liquid to the specific gravity of the liquid (the specific gravity of the solid / the specific gravity of the liquid) is 0.7 to 1.0, the liquid containing the solid particles has a buoyancy caused by the difference in specific gravity Against this, it is possible to circulate the entire inside of the stirring tank more smoothly in a single stroke.
[0064]
FIG. 9 shows an Np-Re diagram showing the power performance of the blade of the stirring device 10 (FIGS. 1 to 3) of the present invention. In the figure, Np is an index indicating the power performance of the liquid by the blades, and is called the power number, P / ρ · n ^Three ・ D ^Five It is represented by Where P: power (W), ρ: liquid density (kg / m ^Three ), N: blade rotation speed (1 / sec), d: paddle blade length (m).
[0065]
Still liquid depth H = 0.29m, tank diameter D = 0.29m, paddle blade length d = 0.155m, middle stage comb blade length d ₁ = 0.0775m, middle comb-like wing height h ₁ = 0.11 m, upper stirring blade length d ₂ = 0.0465m, upper comb wing height h ₂ = 0.11 m. The liquid volume was 16.97 L. The distance between the static liquid level and the upper end of the upper stirring blade was 3% of the static liquid depth.
[0066]
In the case of containing only water, the case of containing polypropylene particles (specific gravity 0.91) as particles 1: water 2 (weight ratio) and the case of containing particles 1: water 1 (weight ratio) were examined. The liquid density was calculated as 1000 for water alone, 966 for water 1: 2 and 952 for water 1: water depending on the content of polypropylene particles. The shape of the polypropylene particles was an elliptic cylinder, and the length was 2.6 mm to 3.2 mm, the major axis of the elliptical cross section was 1.0 mm to 1.3 mm, and the minor axis was 0.7 mm to 0.9 mm.
[0067]
FIG. 9 shows the relationship between the stirring Reynolds number (Re) and the power number (Np) in the stirring apparatus of the present invention when only water is included as the fluid.
[0068]
As for the baffle plate, in addition to the case of two baffle plates with a gap ratio (dg / D) of 4.8% as shown in Fig. 1, when the three baffle plates with a width ratio of 4.8% are installed at 120 degree intervals, the width ratio This also shows the case where three 7.9% baffle plates are installed at intervals of 120 degrees, and four baffle plates with a width ratio of 9.0% are installed at intervals of 90 degrees.
[0069]
In the region where Re is 4000 to 100,000, the Np value is almost constant, and on average, 2.48 for two baffle plates with a width of 4.8% of the tank diameter D (hereinafter referred to as “4.8% x 2 baffle plates”) Etc.), baffle plate 4.8% x 3 pieces 3.36, baffle plate 7.9% x 3 pieces 4.62 and baffle plates 9.0% x 4 pieces 5.07. Similarly, the case of particle 1: water 2 and the case of particle 1: water 1 are shown in Table 1 together with comparative examples.
[0070]
[Table 1]

[0071]
FIG. 4 shows, as an example of a conventional stirring device, stirring device A in which comb-shaped

blades

24 and 25 are exactly the same among the stirring devices described in JP-A-10-24230. This stirring device A has the same shape as the stirring device of the present invention except for the uppermost comb-like wing shape.
[0072]
5 and 6, as an example of a conventional stirring device that can be widely used from a laminar flow region to a turbulent flow region, a paddle blade whose bottom end is slidably contacted with the inner surface of the bottom of the stirring vessel, and a lattice blade and a stirring vessel connected to the paddle A stirrer B in which a baffle plate extending in the axial direction is provided on the inner surface of the wall is shown (see JP-A-6-312122). Here, a stirring shaft 32 is disposed in the central portion of the stirring tank 31. The reference numeral is a large wing composed of a paddle wing at the lower part and a lattice-like wing provided continuously at the upper part. In the present embodiment, the baffle plate 36 is installed as in the apparatus of the present invention.
[0073]
7 and 8 show a conventional stirring device C using an H-shaped blade that is used as a blade for improving the overall mixing.
[0074]
FIG. 10 shows an Np-Re diagram in the case of using the conditions adopted in the stirring device A, the stirring device B, and the stirring device C when obtaining the Np-Re diagram by the stirring device of the present invention described above. It was.
[0075]
In the stirrers A and B, the Np value is almost constant in the region where Re is 4000 to 100,000, and when only water is included as the fluid, on average, the baffle plate of the stirrer A is 4.8%. It was 4.95 in the case of 9.0% × 4 plates, 2.49 in the case of 4.8% × 2 baffle plates of the stirring device B, and 5.09 in the case of 9.0% × 4 baffle plates.
[0076]
As shown in Table 1, the stirring efficiency when compared with the value of Np is almost the same as that of the stirring device A and the stirring device B, and these are higher than the stirring device C. It can be seen that the stirring device C is less efficient than the other blades.
[0077]
In addition, when the polypropylene particles (specific gravity 0.91) are contained in particles 1: water 2 (weight ratio) and the particles 1: water 1 (weight ratio) are included, the stirring efficiency is compared with the Np value in this example. It can be seen that the stirrer, stirrer A, and stirrer B are substantially the same, and exceed stirrer C (Table 1).
[0078]
(Example 1)
Using the stirring device 10 of the present invention shown in FIG. 1, polypropylene particles under the conditions employed when obtaining the Np-Re diagram by the above-described stirring device of the present invention (except for the conditions described below) 1: Table 2 shows the observation result of the mixed state in the case of water 2 (weight ratio), the determination result of the fluid state and the mixed state of the mixed solution.
[0079]
[Table 2]

[0080]
Here, the baffle plate is a case where the width ratio is 4.8% × 2 and the shape of the polypropylene particles is an elliptical column shape, the length is 2.6 mm to 3.2 mm, the major axis of the elliptical cross section is 1.0 mm to 1.3 mm, and the minor axis is 0.7 mm. The one of ~ 0.9 mm was used.
[0081]
In the apparatus of the present invention, the rotation speed of stirring is 150 rpm or more (power per unit volume is 0.227 kW / m ^Three In the above, a vertical circulation flow was generated, and a good mixed state was obtained as a whole. In addition, the rotation speed of stirring is 250 rpm (power per unit volume is 1.058 kW / m ^Three ), The particles near the liquid surface did not scatter and the upper and lower mixing became better.
[0082]
On the other hand, in the stirrers A and B, although the stirring rotation number is 150 rpm, the flow in the rotation direction is strong near the surface, and the mixing performance is slightly worse than that of the stirrer of the present invention. Further, the flow in the rotation direction becomes stronger as the stirring rotation speed is increased. This is because the blade length of the stirring blade in the vicinity of the liquid surface is the same as the blade length of the lower stirring blade. This is thought to be blocked by the discharge flow.
[0083]
On the other hand, in the apparatus of the present invention, the blade length d of the uppermost comb-like wing ₂ (Fig. 1) has a shorter configuration than the lower comb-shaped wing, so that the flow rising up the wall smoothly reaches the liquid surface, and the particles reaching the liquid surface are caused by the vortex generated in the center of the tank. There is an effect that it is sucked up to the bottom of the tank along the stirring shaft. Also for this vortex, a wide comb-shaped wing becomes too large, pushing the flow in the radial direction, causing stagnation of particles near the baffle plate, and does not contribute to smooth suction.
[0084]
In the stirrer C, the discharge flow in the vicinity of the tank height ½ is divided into upper and lower parts, and a flow separated into a lower half and an upper half is generated. Further, the flow in the rotational direction is strong, and the upper and lower mixing becomes extremely poor. In addition, since the blade area is large, the force to push the particles becomes strong, and when the number of stirring rotations is increased, the phenomenon that solid particles scatter violently occurs.
[0085]
Similarly, in the case of 2 sheets of 4.8% baffle plates, the case of polypropylene particles 1: water 1.5 is shown in Table 3, and the case of polypropylene particles 1: water 1 is shown in Table 4.
[0086]
[Table 3]

[0087]
[Table 4]

[0088]
As the ratio of the solid particles increases, the stagnation of the baffle plate on the front side in the rotation direction becomes more conspicuous. Further, when the blade length of the stirring devices A, B, etc. is the same as that of the lower paddle blade, the fluidity of the upper portion is deteriorated, and the overall mixing property is also deteriorated.
[0089]
However, in the stirring device of the present invention, the upward flow smoothly reaches near the liquid surface and there is a slight stagnation near the baffle plate, but it does not hinder the entire mixing. Particle 1: Even in the case of water 1, the rotational speed of stirring is 150 rpm or more (power per unit volume is 0.363 kW / m ^Three Above), the mixing property was good.
[0090]
(Example 2)
Using the mixing apparatus 10 used in Example 1, except for solid particles, polyethylene terephthalate (PET) particles (specific gravity 1.38) 1: water 2 (weight ratio) under the same conditions as in Example 1. Table 5 shows the determination result of the mixing property in comparison with the case of using substantially the same shape of polypropylene (PP) particles.
[0091]
[Table 5]

[0092]
Here, the baffle plate is a case where the width ratio is 4.8% × 2 and the shape of the polyethylene terephthalate particles is an elliptical column shape, the length is 2.6 mm to 3.2 mm, the major axis of the elliptical cross section is 1.0 mm to 1.3 mm, and the minor axis is 0.7. The thing of mm-0.9mm was used.
[0093]
(Example 3)
Using the mixing apparatus 10 used in Example 1, except for solid particles, the determination result of the mixing property in the case of spherical polypropylene particles 1: water 2 (weight ratio) under the same conditions as in Example 1 Table 6 shows a comparison with the case of polypropylene particles.
[0094]
[Table 6]

[0095]
Here, the baffle plate is a case where the width ratio is 4.8% × 2 and the shape of the polypropylene particles is spherical and the diameter is 2.0 mm to 2.2 mm. Even when the solid particles were spherical, good mixing was exhibited as in the case of pellets.
[0096]
(Example 4)
Table 7 shows the determination results of the mixing property when the inclination angle β is changed under the same conditions as in Example 1 except for the inclination angle β by using the stirring device used in Example 2.
[0097]
[Table 7]

[0098]
Here, the baffle plate has a width ratio of 4.8% × 2 sheets.
[0099]
(Example 5)
Table 8 shows the determination results of the mixing property when the height ratio h / H is changed under the same conditions as in Example 1 except for the height ratio h / H using the stirring device used in Example 2. Show.
[0100]
[Table 8]

[0101]
Here, the baffle plate has a width ratio of 4.8% × 2 sheets.
[0102]
(Example 6)
Table 6 shows determination results of mixing properties when the mixing ratio of solid particles and liquid is changed under the same conditions as in Example 1 except for the mixing ratio of solid particles and liquid using the stirring device used in Example 2. 9 shows.
[0103]
[Table 9]

[0104]
Here, the baffle plate has a width ratio of 4.8% × 2 sheets.
[0105]
(Example 7)
The detachment color by iodine and hypo reaction was performed, and the mixing time in the stirring tank was examined. Using the same apparatus as in Example 1, the decolorization time in the case of polypropylene particles 1: water 1.5 was measured and the results were as shown in Table 10.
[0106]
[Table 10]

[0107]
Here, the baffle plate is a case where the width ratio is 4.8% × 2, and the shape of the polypropylene particles is an elliptic cylinder, the length is 2.6 mm to 3.2 mm, the major axis of the elliptical cross section is 1.0 mm to 1.3 mm, and the minor axis is 0.7. The thing of mm-0.9mm was used.
[0108]
When the decolorization times of the stirring device of the present invention and the stirring device C are compared at a stirring rotational speed at which the power required for stirring is substantially equal, the time of the present invention is half, and even when a large amount of particles is contained, It shows that the mixing performance of is very good.
[0109]
【The invention's effect】
The present invention has the following effects by the above configuration.
Even when particles having a particle concentration in the liquid of about 15 to 42 vol% are dispersed at a high concentration, a large axial circulation flow is generated in the stirring tank, and a stagnant portion is present in the tank. There are few, and the situation where a solid particle does not scatter to the air above the liquid level under stirring can be created. As a result, the mixing in the stirring tank proceeds well, the mass transfer between the liquid and the solid in the stirring tank, the heat transfer and the reaction proceed well, and the liquid and the gas phase pass through the liquid level. Good mass transfer can be expected even between the parts.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view of a stirring device according to the present invention.
FIG. 2 is a schematic vertical side view of the stirring device of the present invention.
FIG. 3 is a schematic cross-sectional plan view of the stirring device of the present invention.
FIG. 4 is a schematic perspective view of a stirring blade (stirring apparatus A) disclosed in Japanese Patent Laid-Open No. 10-024230.
FIG. 5 is a schematic perspective view of a stirring blade (stirring apparatus B) disclosed in Japanese Patent Laid-Open No. 6-312122.
FIG. 6 is a schematic vertical side view of a stirring blade (stirring apparatus B) disclosed in Japanese Patent Laid-Open No. 6-312122.
FIG. 7 is a schematic perspective view of an H-shaped stirring blade (stirring device C).
FIG. 8 is a schematic vertical side view of an H-shaped stirring blade (stirring device C).
FIG. 9 is an Np-Re diagram when the stirring blade of the present invention is used.
[Fig. 10] Np-Re diagram when stirring devices A, B and C are used.
[Explanation of symbols]
1: Stirring tank
2: Stirring shaft
3: Paddle wing
3a, 3b: Wide stirring blade
4a, 4b: Middle comb-like wings
5a, 5b: Upper comb-like wings
6: Baffle plate
7: Inner wall surface of stirring tank
8: Plate-shaped mirror plate
9: Lower edge of paddle wing
10: Stirrer according to the present invention
20: Stirrer A disclosed in JP-A-10-24230
30: Single gate type stirring device B
31: Stirring tank
32: Stirring shaft
36: Baffle plate
40: H-type stirring device
47: H type stirring blade

Claims

An agitation tank containing a mixture of solid particles and liquid;
An agitation shaft disposed substantially perpendicular to the stationary liquid surface of the mixed liquid in the agitation tank;
A wide stirring blade supported at the lowermost stage of the stirring shaft;
A plurality of comb-shaped blades that are sequentially arranged in a step shape above the wide stirring blade and are respectively supported by the stirring shaft;
Including
The wide stirring blade is located at the bottom of the stirring tank,
The middle stage comb-shaped blade, which is a comb-shaped blade adjacent to the wide stirring blade, is disposed in front of the wide stirring blade at an angle of less than 90 degrees with respect to the rotation direction of the stirring shaft, and the axial direction of the stirring shaft Having an overlap with the wide stirring blade,
The upper comb-like wings, which are comb-like wings other than the middle-stage comb-like wings, are disposed in front of the lower adjacent comb-like wings at an angle of less than 90 degrees in the rotation direction of the stirring shaft, and the stirring shaft Having an overlap with the adjacent comb-shaped wing in the axial direction of
The blade length of each upper comb-like wing is shorter than the blade length of the adjacent comb-like wing, and the upper comb-like wing has one comb and the middle comb-like wing has two combs,
When the stirring is stopped, a part of the uppermost comb-like wings do not protrude from the stationary liquid surface of the mixed liquid.
Stirring device.

The stirrer according to claim 1, wherein the upper comb-like wing has one stage.

The stirrer according to claim 1 or 2, wherein a blade length of each comb-like wing is 0.5 to 0.9 times a blade length of the comb-like wing adjacent to the lower side.

The stirrer according to any one of claims 1 to 3, wherein a distance between a static liquid level and an upper end of the uppermost comb-like wing is 0 to 5% of a static liquid depth of the mixed liquid.

The direction from the stirring shaft toward the tip of the middle comb-shaped blade along the length of the middle comb-shaped blade is constant between 5 and 75 degrees above or below the direction perpendicular to the stirring shaft. With a slope of
The direction from the stirring shaft toward the tip of each upper comb blade along the length of each upper comb blade has the constant inclination with respect to the direction perpendicular to the stirring shaft. The stirring apparatus in any one of.

The stirring device according to claim 5, wherein the constant inclination is 25 to 35 degrees up or down.

The stirring device according to any one of claims 1 to 6, wherein a plurality of baffle plates are vertically mounted on a wall in the stirring tank.

The degree of overlap of the intermediate comb blade and the wide stirring blade with respect to the axial height from the lower end of the wide stirring blade to the upper end of the uppermost comb blade is 2.5 to 5%. The stirring apparatus in any one of thru | or 7.

The degree of overlap of each comb-shaped blade and the lower adjacent comb-shaped blade with respect to the axial height from the lower end of the wide stirring blade to the upper end of the uppermost comb blade is 2.5 to 5%. The stirrer according to any one of claims 1 to 8.

A method for stirring a mixed solution using the stirring device according to claim 1,
Put the mixed liquid of solid particles and liquid into a stirring tank,
Rotating a stirring shaft disposed in the stirring tank to stir the mixed solution to form a vortex centered on the stirring shaft,
Creating a downward flow along the liquid surface of the mixture in which the vortex is formed;
Reversing the descending flow at the bottom of the agitation tank and ascending the flow along the inner wall of the agitation tank,
A method of stirring a mixed solution, wherein the mixed solution is inverted and circulated again at the top of the mixed solution.

The specific gravity of the solid particles specific gravity less than the liquids, stirring method of the mixture of the mounting serial to claim 10.

The method for stirring a mixed solution according to claim 10 or 11, wherein the solid particles are a pellet-shaped resin.

The method for stirring a liquid mixture according to any one of claims 10 to 12 , wherein the volume concentration of the solid particles in the liquid mixture is 15 to 42 vol.%.