JP3609934B2

JP3609934B2 - Measuring method of particle size

Info

Publication number: JP3609934B2
Application number: JP04897098A
Authority: JP
Inventors: 正人馬場; 泰治野中; 伸司小栗; 雄一長橋
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 1998-02-12
Filing date: 1998-02-12
Publication date: 2005-01-12
Anticipated expiration: 2018-02-12
Also published as: JPH11230887A

Description

【０００１】
【発明の属する技術分野】
本発明は、流動状態にある粉体を構成する粒子の粒径の測定方法と、粉体を流動させることで行われる造粒の制御方法に関する。
【０００２】
【従来の技術と発明が解決しようとする課題】
粉体構成粒子の粒径測定は、医薬、農薬、洗剤等の製造工程において、所望の粒径の粒子を得る上で必要とされる。例えば、特開昭６３‐２３２８３１号公報により開示された造粒終点制御装置は、造粒を行うために粉体を攪拌容器内で攪拌用ロータにより流動させる際に、その攪拌容器内に設けたプローブへの粉体の衝突圧を検出し、その衝突圧を電気信号に変換して高速フーリエ変換することで、その攪拌用ロータの回転数と攪拌羽根の枚数との積に対応する特徴周波数での振動強度を求める。その振動強度が粉体構成粒子の粒径に対応することから、その振動強度が所定値に達した時点で造粒を終了することで、所望粒径の粉体を得ることができる。
【０００３】
しかし、上記従来技術では、その特徴周波数は攪拌用ロータの回転数と攪拌羽根の枚数との積であることから、その特徴周波数での振動強度は、プローブ付近を通過する攪拌羽根に随伴される粒子とプローブとの衝突圧に対応する。そのため、上記従来技術は、プローブに衝突する粒子流量が攪拌羽根により周期的に変動する場合にのみ適用できるものであり、粒子流量が一定であるような場合には適用できず汎用性に欠けるという問題がある。さらに、その特徴周波数は、攪拌用ロータの回転数と攪拌羽根の枚数との積であることから数十Ｈｚ程度と比較的低周波であり、そのため周囲に存在する他の機器の振動等に基づく雑音の影響が大きく精度良く造粒終点を求めることができない。
【０００４】
また、特開平５‐２３７３５７号公報に開示された造粒状態検出方法は、造粒を行うために粉体を攪拌容器内でインペラにより流動させる際の容器の振動強度と、容器を空の状態にしてインペラを駆動した場合の容器の振動強度とを求め、両者を明確に識別させる周波数を特定周波数としている。その特定周波数での振動強度と粉体の嵩密度とが相関関係にあることに着目し、その振動強度に対応する嵩密度に応じて造粒状態を検出している。その特定周波数での振動強度を容器外部に取り付け設けた検出器により検出することで、検出感度が経時劣化するのを防止し、また、容器内部での粉体の運動状態の変動に左右されることなく造粒状態を検出している。
【０００５】
しかし、上記第２の従来技術では、その特定周波数は数十Ｈｚ程度と比較的低周波であり、そのため周囲に存在する他の機器の振動等に基づく雑音の影響が大きく精度良く造粒状態を検出できない。また、その特定周波数での振動強度が粉体の嵩密度と相関関係にあることに基づいているため、その粉体構成粒子が例えば、造粒中に化学反応等を生じる物質を含む場合、その化学反応等により粒子の表面性状等が変化して嵩密度が変動する。そうすると、その振動強度が粉体の嵩密度に相関しなくなり、造粒状態を検出できなくなる。
【０００６】
本発明は、上記問題を解決することのできる粒径の測定方法および造粒制御方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明の粒径測定方法の第１の特徴は、流動状態にある粉体を構成する粒子の粒径を測定するに際して、その粉体の流動領域に位置する部位と粉体との衝突により、その粉体の流動領域に位置する部位に生じる振動の、固有振動数を含む予め定めた周波数帯の強度を検出し、前記粒子の粒径と上記周波数帯の振動強度との予め求めた関係に基づき、その検出した周波数帯の振動強度に対応する粒径を求める点にある。
本発明の粒径測定方法の第２の特徴は、造粒を行うために粉体を流動させる際に、その粉体の流動領域に位置する部位と粉体との衝突により、その粉体の流動領域に位置する部位に生じる振動の、固有振動数を含む予め定めた周波数帯の強度を検出し、前記粒子の粒径と上記周波数帯の振動強度との予め求めた関係に基づき、その検出した周波数帯の振動強度に対応する粒径を求める点にある。
流動状態にある粉体構成粒子の粒径は、その粉体の流動領域に位置する部位と粉体との衝突により生じる振動の、固有振動数を含む予め定めた周波数帯の強度に相関させることができる。これは、その粒径が大きくなる程に粉体の流動領域に位置する部位と粉体との衝突圧が大きくなることに基づく。よって、その粒径とその周波数帯の振動強度との予め求めた関係から、その周波数帯の振動強度の検出値に対応する粉体構成粒子の粒径を求めることができる。
その粒径と周波数帯の振動強度との相関関係は、粉体構成粒子の流量や表面性状の影響を受けることは少ないので、その流量や表面性状の影響をあまり受けずに粒径を精度良く測定できる。しかも、上記周波数帯の下限値を５００Ｈｚ以上にすることで、好ましくはその固有振動数として高次のものを選定することで、周囲の低周波振動等に基づく雑音の影響を防止できる。
【０００８】
本発明の造粒制御方法の第１の特徴は、造粒を行うために粉体を流動させる際に、その粉体の流動領域に位置する部位と粉体との衝突により、その粉体の流動領域に位置する部位に生じる振動の、固有振動数を含む予め定めた周波数帯の強度を検出し、その検出した周波数帯の振動強度が、粉体構成粒子の目標粒径に対応する予め定めた設定値である時に、その造粒を終了させる点にある。
上記のように粒径と周波数帯の振動強度との相関関係は、粉体構成粒子の流量や表面性状の影響を受けることは少ないので、この構成によれば、造粒の終点を精度良く求めることができる。
【０００９】
本発明の造粒制御方法の第２の特徴は、造粒を行うために粉体を流動させる際に、その粉体の流動領域に位置する部位と粉体との衝突により、その粉体の流動領域に位置する部位に生じる振動の、固有振動数を含む予め定めた周波数帯の強度を時系列に検出し、造粒開始から任意時間経過時点において検出した周波数帯の振動強度を、造粒開始からの経過時間と粉体構成粒子の基準粒径に対応する前記周波数帯の振動強度との予め定めた関係と比較し、その検出した周波数帯の振動強度と基準粒径に対応する周波数帯の振動強度との差を低減するように、造粒条件を変更する点にある。
造粒開始から任意時間の経過時点において検出した周波数帯の振動強度と基準粒径に対応する周波数帯の振動強度との差は、その時点における粉体構成粒子の実際の粒径と基準粒径との差に対応する。その基準粒径は任意に設定できる。よって、その差を低減するように造粒条件を変更することで、粉体構成粒子の流量や表面性状の影響を受けることは少なく、粉体構成粒子の粒径を任意の目標値に精度良く近付けることができる。
【００１０】
上記造粒過程において粉体構成粒子が凝集することで生じる新たな粒子は、その造粒過程において化学反応する物質を含むものであってもよい。この場合、その化学反応により粉体構成粒子の表面性状が変動しても、粒径を精度良く測定したり、造粒の終点を精度良く求めたり、粒径を目標値に精度良く近付けることができる。
【００１１】
上記造粒過程における粉体は、容器内で軸中心に回転駆動される攪拌部材により攪拌されることで流動されると共に、その攪拌部材の回転軸の外周部に対向する容器の内周部に回転駆動可能に設けられる粉砕部材により粉砕され、前記振動強度として、その粉砕部材と粉体との衝突により生じる振動の強度が検出されるのが好ましい。その粉砕部材と粉体との衝突により生じる振動強度は、その粉体構成粒子の粒径を良く反映するので、その振動強度を検出することで、造粒の終点を精度良く求めたり、粒径を目標値に精度良く近付けることができる。
【００１２】
【発明の実施の形態】
図１、図２を参照して本発明の第１実施形態を説明する。
第１実施形態においては、ホッパー１から落下することで流動状態にある粉体の構成粒子２の粒径が測定される。すなわち、その粉体の流動領域に位置する振動板３が支持部材６により片持ち梁状に支持される。その粉体と振動板３との衝突により生じる振動の強度を時系列に検出する加速度センサ等のセンサ４が、その振動板３に取り付けられ、そのセンサ４は信号処理装置５に接続される。
【００１３】
その信号処理装置５は、主増幅器５ａ、バンドパスフィルター５ｂ、補助増幅器５ｃ、実効値変換回路５ｄ、Ａ／Ｄ変換器５ｅ、および演算装置５ｆを有する。
【００１４】
そのセンサ４から送られる振動強度の検出信号は、その主増幅器５ａにより増幅され、バンドパスフィルター５ｂにより予め定めた周波数帯以外の信号が除去され、補助増幅器５ｃにより増幅され、実効値変換回路５ｄによりその周波数帯の強度に対応する実効値に相当する値の直流信号に変換され、Ａ／Ｄ変換器５ｅによってＡ／Ｄ変換された後に演算装置５ｆに入力される。
【００１５】
そのバンドパスフィルター５ｂを通過する信号の周波数帯は、その粉体と振動板３との衝突により生じる振動の固有振動数を含むように定められ、その具体的な値は粒径を所望の精度で求めることができるように実験により予め定めることができ、その下限値は５００Ｈｚ以上であるのが好ましい。これにより、その粉体と振動板３との衝突により生じる振動の、固有振動数を含む予め定めた周波数帯の強度が検出される。
【００１６】
その演算装置５ｆはコンピュータにより構成され、その粒子２の粒径と上記周波数帯の振動強度との予め求めた関係を記憶し、その検出された上記周波数帯の振動強度に対応する粒子２の粒径を、その記憶した関係から求める。また、その演算装置５ｆに、キーボード等の入力装置７、外部記憶装置やプリンター等のデータ記録部８、ＣＲＴや液晶ディスプレイ等の表示部９が接続され、入力装置７から操作信号が入力され、その求められた粒径はデータ記録部８や表示部９に出力される。
【００１７】
図２（１）は、その粉体と振動板３との衝突により生じる周波数毎の振動強度の一例を示し、本実施形態では、図においてＡで示す範囲の固有振動数を含む予め定めた周波数帯（例えば３４００〜４６００Ｈｚ）の振動強度として実効値が求められる。ここでいう振動強度は下記の式による交流信号の実効値演算により計算しているが、交流信号の絶対値の時間平均などを用いて振動強度としてもよい。
【００１８】
【数１】

【００１９】
図２（２）は、予め粒径が定められた粒子２から構成される流動状態にある粉体と振動板３との衝突により生じる振動の、上記周波数帯の強度と粒径との関係の一例を示し、図における○は測定点を示す。尚、粒径（平均粒径を示す）の測定方法は、複数の特定メッシュのふるいを用いて、サンプルをふるい分けし、積算重量で５０％となるところのメッシュをサンプルの粒径とする。これより、その周波数帯の振動強度と粒径とは相関し、その粒径が大きくなる程に周波数帯の振動強度が大きくなるのを確認できる。よって、その粒径と周波数帯の振動強度との記憶した関係から、その周波数帯の振動強度の検出値に対応する粉体構成粒子２の粒径を求めることができる。直線Ｂは、その演算装置５ｆに記憶される粒径と周波数帯の振動強度との関係の一例を示す。
【００２０】
上記構成によれば、粉体構成粒子２の粒径と振動強度との相関関係は、粉体構成粒子２の流量や表面性状の影響を受けることは少ないので、その流量や表面性状の影響をあまり受けずに粒径を精度良く測定できる。しかも上記周波数帯の下限値を５００Ｈｚ以上にすることで、好ましくはその固有振動数として高次のものを選定することで、周囲の低周波振動等に基づく雑音の影響を防止できる。
【００２１】
図３、図４を参照して本発明の第２実施形態を説明する。
第２実施形態においては、造粒を行うために粉体を第１、第２造粒装置１１、１２内で流動させる。
【００２２】
その第１造粒装置１１は、横軸心の円筒形状を有する攪拌容器１１ａと、この容器１１ａ内で原動機１１ｂにより横軸１１ｃ中心に回転駆動されるブレード状の攪拌部材１１ｄと、その攪拌部材１１ｄの回転軸１１ｃの外周部に対向する容器１１ａの内周部に設けられるブレード状の粉砕部材１１ｅとを備える。その粉砕部材１１ｅは粉体の流動領域に位置し、容器１１ａにより片持ち梁状に支持され、原動機１１ｆにより容器１１ａの径方向に沿う軸中心に回転駆動される。その粉体は、容器１１ａ内で攪拌部材１１ｄにより攪拌されることで流動されると共に、その粉砕部材１１ｅにより粉砕される。また、その容器１１ａ内に図外パイプから、その粉体を粒状にするための造粒液や、粉体と接触することで化学反応を生じる反応液等が供給される。その粉体と粉砕部材１１ｅとの衝突により生じる振動の強度を検出するセンサ１４ａが、その粉砕部材１１ｅの原動機１１ｆに取り付けられ、そのセンサ１４ａは信号処理装置１５に接続される。
【００２３】
その第２造粒装置１２は、縦軸心の筒形状を有する攪拌容器１２ａと、この容器１２ａ内で原動機１２ｂにより縦軸１２ｃ中心に回転駆動されるブレード状の攪拌部材１２ｄと、その攪拌部材１２ｄの回転軸１２ｃの外周部に対向する容器１２ａの内周部に設けられるブレード状の粉砕部材１２ｅとを備える。その粉砕部材１２ｅは粉体の流動領域に位置し、容器１２ａにより片持ち梁状に支持され、原動機１２ｆにより容器１２ａの径方向に沿う軸中心に回転駆動される。その粉体は、容器１２ａ内で攪拌部材１２ｄにより攪拌されることで流動されると共に、その粉砕部材１２ｅにより粉砕される。また、その容器１２ａ内に図外パイプから、その粉体を粒状にするための造粒液や、粉体と接触することで化学反応を生じる反応液等が供給される。その粉体と粉砕部材１２ｅとの衝突により生じる振動の強度を検出するセンサ１４ｂが、その粉砕部材１２ｅの原動機１２ｆに取り付けられ、そのセンサ１４ｂは上記信号処理装置１５に接続される。
【００２４】
その信号処理装置１５は、第１、第２主増幅器１５ａ′、１５ａ″、第１、第２バンドパスフィルター１５ｂ′、１５ｂ″、第１、第２補助増幅器１５ｃ′、１５ｃ″、第１、第２実効値変換回路１５ｄ′、１５ｄ″、第１、第２Ａ／Ｄ変換器１５ｅ′、１５ｅ″、および制御装置１５ｆを有する。
【００２５】
第１の主増幅器１５ａ′、バンドパスフィルター１５ｂ′、補助増幅器１５ｃ′、実効値変換回路１５ｄ′、Ａ／Ｄ変換器１５ｅ′は、上記第１造粒装置１１のセンサ１４ａから送られる振動強度の検出信号を、第２の主増幅器１５ａ″、バンドパスフィルター１５ｂ″、補助増幅器１５ｃ″、実効値変換回路１５ｄ″、Ａ／Ｄ変換器１５ｅ″は、上記第２造粒装置１２のセンサ１４ｂから送られる振動強度の検出信号を、それぞれ第１実施形態の信号処理装置５と同様に処理し、各処理信号それぞれは制御装置１５ｆに入力される。
【００２６】
第１バンドパスフィルター１５ｂ′を通過する信号の周波数帯は、その粉体と第１造粒装置１１の粉砕部材１１ｅとの衝突により生じる振動の固有振動数を含むように定められ、第２バンドパスフィルター１５ｂ″を通過する信号の周波数帯は、その粉体と第２造粒装置１２の粉砕部材１２ｅとの衝突により生じる振動の固有振動数を含むように定められ、それぞれの具体的な値は粒径を所望の精度で求めることができるように実験により定めることができ、各下限値は５００Ｈｚ以上であるのが好ましい。これにより、粉体と各粉砕部材１１ｅ、１２ｅとの衝突により生じる振動それぞれの、固有振動数を含む予め定めた周波数帯の強度が検出される。
【００２７】
その制御装置１５ｆはコンピュータにより構成され、キーボード等の入力装置１７、外部記憶装置やプリンター等のデータ記録部１８、ＣＲＴや液晶ディスプレイ等の表示部１９が接続される。
【００２８】
その制御装置１５ｆは記憶装置を内蔵し、第１造粒装置１１において造粒される粉体構成粒子の粒径と第１バンドパスフィルター１５ｂ′を通過する信号の周波数帯の振動強度との予め定められた関係、第１造粒装置１１において造粒される粉体構成粒子の目標粒径に対応する予め求めた第１バンドパスフィルター１５ｂ′を通過する信号の周波数帯の振動強度である第１設定値、第２造粒装置１２において造粒される粉体構成粒子の粒径と第２バンドパスフィルター１５ｂ″を通過する信号の周波数帯の振動強度との予め定められた関係、および第２造粒装置１２において造粒される粉体構成粒子の目標粒径に対応する予め求めた第２バンドパスフィルター１５ｂ″を通過する信号の周波数帯の振動強度である第２設定値とを記憶する。
【００２９】
そして制御装置１５ｆは、その第１造粒装置１１において検出された上記周波数帯の振動強度に対応する粒径と、第２造粒装置１２において検出された上記周波数帯の振動強度に対応する粒径とを演算し、その演算結果をデータ記録部１８や表示部１９に出力する。
【００３０】
また、その制御装置１５ｆは、その第１造粒装置１１において検出された上記周波数帯の振動強度が第１設定値である時は、第１造粒装置１１の各原動機１１ｂ、１１ｆを停止させる制御信号を出力し、第１造粒装置１１による造粒を終了させ、その第２造粒装置１２において検出された上記周波数帯の振動強度が第２設定値である時は、第２造粒装置１２の各原動機１２ｂ、１２ｆを停止させる制御信号を出力し、第２造粒装置１２による造粒を終了させる。
【００３１】
図４（１）は、第１造粒装置１１において、粉体と粉砕部材１１ｅとの衝突により生じる周波数毎の振動強度の一例を示し、本実施形態では、図においてＣで示す範囲の固有振動数を含む予め定めた周波数帯（例えば２８００〜３２００Ｈｚ）の振動強度として実効値が求められる。
【００３２】
図４（２）は、第１造粒装置１１において、予め粒径が定められた粒子から構成される流動状態にある粉体と粉砕部材１１ｅとを衝突させた場合の、その衝突により生じる振動の上記周波数帯の強度と粒径との関係の一例を示し、図における○は測定点を示す。これより、その粒径と周波数帯の振動強度は相関し、その粒径が大きくなる程に振動強度が大きくなるのを確認できる。よって、その周波数帯の振動強度と粒径との記憶した関係から、その振動強度の検出値に対応する粉体構成粒子の粒径を求めることができる。直線Ｄは、その制御装置１５ｆに記憶される粒径と周波数帯の振動強度との関係の一例を示す。また、粉体構成粒子の目標粒径に対応する上記周波数帯の振動強度である第１設定値を記憶する場合、その直線Ｄで示される関係により、その目標粒径と周波数帯の振動強度との対応関係を求めることができる。第２造粒装置１２においても同様に粒径と周波数帯の振動強度との相関関係を得ることができる。
【００３３】
上記構成によれば、粉体構成粒子の粒径と上記周波数帯の振動強度との相関関係は、粉体構成粒子の流量や表面性状の影響を受けることはないので、その流量や表面性状にかかわりなく粒径を精度良く求め、また、造粒の終点を精度良く求めることができる。さらに、上記各周波数帯の下限値を５００Ｈｚ以上にすることで、好ましくは上記各固有振動数として高次のものを選定することで、その造粒の終点を、周囲の低周波振動等に基づく雑音の影響を受けることなくより精度良く求めることができる。また、粉砕部材１１ｅ、１２ｅと粉体との衝突により生じる振動の上記各周波数帯の強度は、その粉体構成粒子の粒径を良く反映するので、その周波数帯の振動強度を検出することで、粒径を精度良く求め、また、造粒の終点を精度良く求めることができる。
【００３４】
図５〜図８を参照して本発明の第３実施形態を説明する。なお、第２実施形態と同様部分は同一符号で示す。
図５、図６に示すように、第３実施形態と上記第２実施形態との相違は、第１造粒装置１１の攪拌容器１１ａに防振ゴム等の防振部材２０が取り付けられ、その防振部材２０を介して攪拌容器１１ａに第１振動板２１ａと位置調節部材２１ｂと第２振動板２２の一体化したものが取り付けられる。その第１振動板２１ａと位置調節部材２１ｂは攪拌容器１１ａの内部に配置され、第２振動板２２は攪拌容器１１ａの外部に配置される。位置調節部材２１ｂは、第１振動板２１ａに適切に粉体が衝突するようにその長さを適宜変えることができるし、もしくはなくてもよい。攪拌容器１１ａの内部では流動する粉体が第１振動板２１ａに衝突し第１振動板２１ａに振動が生じるとともに、この振動が第２振動板２２にも伝わり第２振動板２２にも振動が生じる。従って、振動板に生じる振動を検出するセンサ２３は、どちらの振動板に取り付けても、攪拌容器１１ａ内部の粉体の粒径の測定は可能である。しかしながら、センサ２３の周囲の環境による劣化や保守の利便性を考慮して、第２振動板２２に取り付ける方がより良い。
第２実施形態において粉体と粉砕部材１１ｅとの衝突により生じる振動強度を検出していたのに代えて、その第１振動板２１ａと粉体との衝突により生じる振動の強度を検出するセンサ２３が、その第２振動板２２に取り付けられ、そのセンサ２３が信号処理装置１５′に接続される。また、攪拌容器１１ａからの粉体取り出し用ゲート弁（図示省略）と、そのゲート弁駆動装置２５が取り付けられている。その防振部材により周囲の低周波振動等に基づく雑音の影響を防止できるので、造粒の終点を精度良く求めたり、粒径を所望の値に精度良く近付けることができる。
【００３５】
第２造粒装置１２は第２実施形態と同様とされ、その信号処理装置１５′に粉体と粉砕部材１２ｅとの衝突により生じる振動の強度を検出するセンサ１４ｂが接続される。
【００３６】
第３実施形態の信号処理装置１５′は、第２実施形態の信号処理装置１５と制御装置を除いては同様とされ、第１造粒装置１１における粉体と第１振動板２１との衝突により生じる振動の固有振動数を含む予め定めた周波数帯の強度と、第２造粒装置１２における粉体と粉砕部材１２ｅとの衝突により生じる振動の固有振動数を含む予め定めた周波数帯の強度とが、それぞれ時系列に検出される。
【００３７】
第３実施形態の信号処理装置１５′の制御装置１５ｆ′は、第１造粒装置１１における造粒開始からの経過時間と粉体構成粒子の基準粒径に対応する第１バンドパスフィルター１５ｂ′を通過する信号の周波数帯の振動強度との予め定めた第１の関係を記憶し、また、第２造粒装置１２における造粒開始からの経過時間と粉体構成粒子の基準粒径に対応する第２バンドパスフィルター１５ｂ″を通過する周波数帯の振動強度との予め定めた第２の関係を記憶する。各基準粒径は、その経過時間と周波数帯の強度との関係が満たされる時、その時点での粉体構成粒子の粒径の目標値になるように設定され、任意の値に設定できる。図７における実線Ｅは、第１造粒装置１１における造粒開始からの経過時間と粉体構成粒子の基準粒径に対応する上記周波数帯の振動強度との関係の一例を示す。
【００３８】
その制御装置１５ｆ′は、造粒開始から任意時間の経過時点において、第１造粒装置１１において検出した周波数帯の振動強度を、上記第１の関係と比較し、その検出した周波数帯の振動強度と基準粒径に対応する周波数帯の振動強度との差を求め、その差を低減するように第１造粒装置１１の造粒条件を変更する。また、制御装置１５ｆ′は、造粒開始から任意時間の経過時点において、第２造粒装置１２において検出した周波数帯の振動強度を、上記第２の関係と比較し、その検出した周波数帯の振動強度と基準粒径に対応する周波数帯の振動強度との差を求め、その差を低減するように第２造粒装置１２の造粒条件を変更する。その差と造粒条件の変更量との関係は予め定められて記憶される。
【００３９】
例えば、バッチプロセスにより造粒を行う場合、各造粒装置１１、１２の攪拌部材１１ｄ、１２ｄや粉砕部材１１ｅ、１２ｅの回転速度を変更対象の造粒条件とすることができ、例えば、原動機１１ｂ、１１ｆ、１２ｂ、１２ｆに制御信号を送ることで造粒条件を変更できる。また、連続プロセスにより造粒を行う場合、粉体の滞留時間を造粒条件とすることができ、例えば、攪拌容器１１ａからの粉体取り出し用ゲート弁の開度制御信号をゲート弁駆動装置２５に送ることで造粒条件を変更できる。
【００４０】
図７における実線Ｆは、造粒開始からの経過時間と検出された上記周波数帯の振動強度との関係の一例を示す。この場合、造粒開始から任意時間ｔａの経過時間において、検出された周波数帯の振動強度は基準粒径に対応する周波数帯の振動強度よりも図中δａだけ小さい。すなわち、その粉体構成粒子の粒径は、任意時間経過時点での目標値である基準粒径よりも、そのδａに対応する値だけ小さい。この場合、その差δａに応じて予め設定されて記憶された量だけ、攪拌部材１１ｄ、１２ｄや粉砕部材１１ｅ、１２ｅの回転速度を減速したり、粉体の滞留時間を長くするために粉体取り出し用ゲート弁の開度を小さくすることができる。
【００４１】
また、図７における実線Ｇは、造粒開始からの経過時間と検出された上記周波数帯の振動強度との関係の別の一例を示す。この場合、造粒開始から任意時間ｔａの経過時間において、検出された周波数帯の振動強度は基準粒径に対応する周波数帯の振動強度よりも図中δｂだけ大きい。すなわち、その粉体構成粒子の粒径は、任意時間経過時点での目標値である基準粒径よりも、そのδｂに対応する値だけ大きい。この場合、その差δｂに応じて予め設定されて記憶された量だけ、攪拌部材１１ｄ、１２ｄや粉砕部材１１ｅ、１２ｅの回転速度を増速したり、粉体の滞留時間を短くするために粉体取り出し用ゲート弁の開度を大きくすることができる。他は第２実施形態と同様とされている。
【００４２】
図８（１）は、第３実施形態において、第１造粒装置１１での粉体と第１振動板２１との衝突により生じる第２振動板２２の周波数毎の振動強度の一例を示し、本実施形態では、図においてＨで示す範囲の固有振動数を含む予め定めた周波数帯（例えば２２００〜２７００Ｈｚ）の振動強度が検出される。図８（２）は、予め粒径が定められた粒子から構成される流動状態にある粉体と第１振動板２１とを衝突させた場合の、その衝突により生じる第２振動板２２の振動の上記周波数帯における強度と粒径との関係の一例を示し、図における○は測定点を示す。これによって、その粒径と周波数帯の振動強度は相関するのを確認できる。直線Ｉは、その相関関係を示す一例である。第１造粒装置１１における造粒開始からの経過時間と粉体構成粒子の基準粒径に対応する上記周波数帯の振動強度との予め定めた上記第１の関係において、その直線Ｈで示される関係により、その基準粒径と周波数帯の振動強度との対応関係を求めることができる。第２造粒装置１２においても同様に粒径と周波数帯の振動強度との相関関係を得ることができる。
【００４３】
上記第３実施形態によれば、造粒開始から任意時間の経過時点において検出した周波数帯の振動強度と基準粒径に対応する周波数帯の振動強度との差は、その時点における粉体構成粒子の実際の粒径と基準粒径との差に対応する。その基準粒径は任意に設定できる。よって、その差を低減するように造粒条件を変更することで、粉体構成粒子の流量や表面性状の影響を受けることなく、粉体構成粒子の粒径を任意の目標値に精度良く近付けることができる。図７より、造粒開始から時間ｔａ経過時点に上記のように造粒条件を変更することで、粉体構成粒子の粒径が基準粒径に近付くのを確認できる。さらに、上記周波数帯の下限値を５００Ｈｚ以上にすることで、好ましくはその固有振動数として高次のものを選定することで、周囲の低周波振動等に基づく雑音の影響を受けることなく、その粒径を目標値により精度良く近付けることができる。また、第１造粒装置１１においては、防振部材２０により周囲の低周波振動等に基づく雑音の影響を防止できるので、粒径を所望の値に精度良く近付けることができる。また、第２造粒装置１２においては、粉砕部材１２ｅと粉体との衝突により生じる周波数帯の振動強度は、その粉体構成粒子の粒径を良く反映するので、その周波数帯の振動強度を検出することで、粒径を目標値に精度良く近付けることができる。なお、第２実施形態においても、第３実施形態と同様の防振部材を介して振動板を設け、その振動板と粉体との衝突により生じる振動の固有振動数を含む周波数帯の強度を求めるようにしてもよい。
【００４４】
上記第２実施形態、第３実施形態における造粒過程において、攪拌容器１１ａ、１２ａ内に粉体と接触することで化学反応を生じる反応液等を供給する場合、粉体構成粒子が凝集されることで生じる新たな粒子は、その造粒過程において化学反応する物質を含む。この場合、その化学反応により粉体構成粒子の表面性状が変動しても、粒径と周波数帯の振動強度との相関関係は粉体構成粒子の表面性状の影響を受けることはないので、粒径や造粒の終点を精度良く求めたり、粒径を目標値に精度良く近付けることができる。
【００４５】
図９（１）は第４実施形態を示し、ベルトコンベヤや振動コンベヤ等の搬送装置３１により粉体を図中矢印方向に搬送する場合において、その搬送途中の粉体と衝突する位置に片持ち梁状の振動板３２が設けられる。これにより、その振動板３２に対して粉体は相対的に流動するので、その振動板３２と粉体との衝突により生じる振動の固有振動数を含む予め定めた周波数帯の強度を、例えば振動板３２に取り付けたセンサ３３により検出し、上記第１実施形態と同様に粉体構成粒子２の粒径を求めることができる。
【００４６】
図９（２）は第５実施形態を示し、ダクト４１内で空気により輸送されることで粉体が流動する場合において、その粉体とダクト４１との衝突により生じる振動の固有振動数を含む予め定めた周波数帯の強度を、例えばダクト４１に取り付けたセンサ４２により検出し、上記第１実施形態と同様に粉体構成粒子２の粒径を求めることができる。
【００４７】
なお、本発明は上記各実施形態に限定されない。例えば、造粒装置の攪拌容器そのものは、その内周部位に粉体が造粒時において衝突することで振動するので、その攪拌容器そのものの予め定めた周波数帯の振動強度を検出するようにしてもよい。また、予め定めた周波数帯の振動強度として実効値を求めるのに代えて、振動強度の検出信号を高速フーリエ変換することで得られる各周波数に対応する振動強度の、その周波数帯における積算値、平均値または最大値を求めてもよい。なお、その周波数帯の振動強度を、バンドパスフィルター及び実効値変換回路を利用して求めることで、高速フーリエ変換を利用して求めるのに比べて迅速に求め、流動状態にある粉体の構成粒子径を略リアルタイムで測定できる。しかも、その周波数帯は攪拌部材の回転数等の造粒操作条件にかかわらず一定にできるため、バンドパスフィルターの中心周波数を変更する必要がなく、装置構成が複雑化するのを防止できる。
【００４８】
【発明の効果】
本発明によれば、粒子流量、粒子の表面性状、周囲の雑音の影響を受けることなく、粒径を精度良く求めることができる汎用可能な粒径の測定方法と、造粒の終点を精度良く求めることができ、造粒時において粒径を所望の値に精度良く近付けることができる造粒制御方法を提供できる。
【図面の簡単な説明】
【図１】本発明の第１実施形態に係る粒径測定方法を実施するための構成説明図
【図２】本発明の第１実施形態における（１）は周波数毎の振動強度を示す図、（２）は予め定めた周波数帯における振動強度と粒径との関係を示す図
【図３】本発明の第２実施形態に係る造粒制御方法を実施するための構成説明図
【図４】本発明の第２実施形態における（１）は周波数毎の振動強度を示す図、（２）は予め定めた周波数帯における振動強度と粒径との関係を示す図
【図５】本発明の第３実施形態に係る造粒制御方法を実施するための構成説明図
【図６】本発明の第３実施形態による造粒制御方法を実施するための構成の要部の説明図
【図７】本発明の第３実施形態による造粒制御方法において時間と予め定めた周波数帯における振動強度との関係を示す図
【図８】本発明の第３実施形態における（１）は周波数毎の振動強度を示す図、（２）は予め定めた周波数帯における振動強度と粒径との関係を示す図
【図９】本発明の（１）は第４実施形態に係る粒径測定方法を実施するための構成説明図、（２）は第５実施形態に係る粒径測定方法を実施するための構成説明図
【符号の説明】
２粒子
３、２１、２２、３２振動板
４、１４ａ、１４ｂ、２３、３３、４２センサ
５ｂ、１５ｂ′、１５ｂ″ バンドパスフィルター
５ｄ、１５ｄ′、１５ｄ″ 実効値変換回路
５ｆ演算装置
１１、１２造粒装置
１１ｅ、１２ｅ粉砕部材
１５ｆ、１５ｆ′ 制御装置
２０防振部材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring the particle size of particles constituting powder in a fluidized state, and a method for controlling granulation performed by flowing the powder.
[0002]
[Prior art and problems to be solved by the invention]
Measurement of the particle size of the powder constituent particles is required to obtain particles having a desired particle size in the production process of pharmaceuticals, agricultural chemicals, detergents and the like. For example, the granulation end point control device disclosed in Japanese Patent Application Laid-Open No. 63-232831 is provided in the stirring vessel when the powder is flowed by the stirring rotor in the stirring vessel for granulation. By detecting the impact pressure of the powder on the probe, converting the impact pressure into an electrical signal and performing fast Fourier transform, the characteristic frequency corresponding to the product of the number of rotations of the stirring rotor and the number of stirring blades is obtained. Obtain the vibration strength of. Since the vibration strength corresponds to the particle size of the powder constituent particles, the powder having a desired particle size can be obtained by terminating the granulation when the vibration strength reaches a predetermined value.
[0003]
However, in the above prior art, the characteristic frequency is the product of the number of rotations of the stirring rotor and the number of stirring blades, so the vibration intensity at that characteristic frequency is accompanied by the stirring blades passing near the probe. Corresponds to the collision pressure between the particle and the probe. Therefore, the above prior art is applicable only when the flow rate of particles colliding with the probe fluctuates periodically due to the stirring blades, and is not applicable when the flow rate of particles is constant and lacks versatility. There's a problem. Furthermore, the characteristic frequency is a product of the number of rotations of the stirring rotor and the number of stirring blades, and is a relatively low frequency of about several tens Hz. Therefore, the characteristic frequency is based on vibrations of other devices present in the surroundings. The influence of noise is large and the granulation end point cannot be obtained with high accuracy.
[0004]
In addition, the granulation state detection method disclosed in Japanese Patent Application Laid-Open No. 5-237357 is based on the vibration strength of the container when the powder is flowed by the impeller in the stirring container to perform the granulation, and the container is in an empty state. Thus, the vibration intensity of the container when the impeller is driven is obtained, and the frequency at which both are clearly identified is defined as the specific frequency. Focusing on the fact that there is a correlation between the vibration intensity at the specific frequency and the bulk density of the powder, the granulated state is detected according to the bulk density corresponding to the vibration intensity. By detecting the vibration intensity at the specific frequency with a detector attached to the outside of the container, it is possible to prevent the detection sensitivity from deteriorating with time and to be influenced by fluctuations in the motion state of the powder inside the container. The granulation state is detected without any problems.
[0005]
However, in the second prior art, the specific frequency is a relatively low frequency of about several tens of Hz. Therefore, the influence of noise based on vibrations of other devices present in the surroundings is large and the granulated state is accurately obtained. It cannot be detected. Further, since the vibration intensity at the specific frequency is based on a correlation with the bulk density of the powder, when the powder constituent particles include a substance that causes a chemical reaction or the like during granulation, for example, The bulk density fluctuates due to changes in the surface properties of the particles due to chemical reaction or the like. Then, the vibration strength does not correlate with the bulk density of the powder, and the granulated state cannot be detected.
[0006]
It is an object of the present invention to provide a particle size measuring method and a granulation control method that can solve the above problems.
[0007]
[Means for Solving the Problems]
The first feature of the particle size measurement method of the present invention is that, when measuring the particle size of the particles constituting the powder in a fluidized state, the collision between the portion located in the flow region of the powder and the powder. In the part located in the flow area of the powder The intensity of a predetermined frequency band including the natural frequency of the generated vibration is detected, and the vibration intensity of the detected frequency band is determined based on a predetermined relationship between the particle diameter of the particle and the vibration intensity of the frequency band. The point is to obtain the corresponding particle size.
The second feature of the particle size measuring method of the present invention is that when the powder is flowed for granulation, it is caused by the collision between the part located in the flow region of the powder and the powder. In the part located in the flow area of the powder The intensity of a predetermined frequency band including the natural frequency of the generated vibration is detected, and the vibration intensity of the detected frequency band is determined based on a predetermined relationship between the particle diameter of the particle and the vibration intensity of the frequency band. The point is to obtain the corresponding particle size.
The particle size of the powder constituent particles in the fluidized state should be correlated with the intensity of a predetermined frequency band including the natural frequency of the vibration caused by the collision between the part located in the flow region of the powder and the powder. Can do. This is based on the fact that as the particle size increases, the collision pressure between the powder located in the flow region of the powder and the powder increases. Therefore, the particle diameter of the powder constituent particles corresponding to the detected value of the vibration intensity in the frequency band can be determined from the relationship obtained in advance between the particle diameter and the vibration intensity in the frequency band.
The correlation between the particle size and the vibration intensity in the frequency band is less affected by the flow rate and surface properties of the powder constituent particles, so the particle size can be accurately adjusted without being affected by the flow rate and surface properties. It can be measured. In addition, by setting the lower limit value of the frequency band to 500 Hz or higher, and preferably selecting a higher order natural frequency, it is possible to prevent the influence of noise based on surrounding low frequency vibrations.
[0008]
The first feature of the granulation control method of the present invention is that, when powder is flowed for granulation, it is caused by collision between a part located in the flow region of the powder and the powder. In the part located in the flow area of the powder When the intensity of a predetermined frequency band including the natural frequency of the generated vibration is detected and the detected vibration intensity of the frequency band is a predetermined set value corresponding to the target particle size of the powder constituent particles, The point is to end the granulation.
As described above, the correlation between the particle size and the vibration intensity in the frequency band is less affected by the flow rate and surface properties of the powder constituent particles. According to this configuration, the end point of granulation is obtained with high accuracy. be able to.
[0009]
The second feature of the granulation control method of the present invention is that when the powder is flowed for granulation, it is caused by the collision between the part located in the flow region of the powder and the powder. In the part located in the flow area of the powder The intensity of the generated frequency band including the natural frequency is detected in time series, and the vibration intensity of the frequency band detected at an arbitrary time point from the start of granulation Compared with a predetermined relationship with the vibration intensity of the frequency band corresponding to the reference particle size of the body constituent particles, the difference between the vibration intensity of the detected frequency band and the vibration intensity of the frequency band corresponding to the reference particle size It is the point which changes granulation conditions so that it may reduce.
The difference between the vibration intensity of the frequency band detected at an arbitrary time from the start of granulation and the vibration intensity of the frequency band corresponding to the reference particle diameter is the actual particle diameter and reference particle diameter of the powder constituent particles at that time. Corresponds to the difference. The reference particle size can be set arbitrarily. Therefore, by changing the granulation conditions so as to reduce the difference, it is less affected by the flow rate and surface property of the powder constituent particles, and the particle size of the powder constituent particles is accurately adjusted to an arbitrary target value. You can get closer.
[0010]
The new particles generated by the aggregation of the powder constituting particles in the granulation process may include a substance that chemically reacts in the granulation process. In this case, even if the surface properties of the powder constituent particles fluctuate due to the chemical reaction, the particle size can be accurately measured, the end point of granulation can be obtained with high accuracy, or the particle size can be brought close to the target value with high accuracy. it can.
[0011]
The powder in the granulation process is fluidized by being agitated by an agitating member that is driven to rotate around the shaft in the container, and also on the inner peripheral portion of the container facing the outer peripheral portion of the rotating shaft of the agitating member. It is preferably pulverized by a pulverizing member provided so as to be able to be driven to rotate, and as the vibration intensity, the intensity of vibration generated by the collision between the pulverizing member and powder is detected. The vibration strength generated by the collision between the pulverized member and the powder reflects the particle size of the powder constituent particles well. Therefore, by detecting the vibration strength, the end point of granulation can be obtained accurately or the particle size can be determined. Can be brought close to the target value with high accuracy.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
In the first embodiment, the particle size of the constituent particles 2 of the powder that is in a fluid state by falling from the hopper 1 is measured. That is, the diaphragm 3 located in the powder flow region is supported by the support member 6 in a cantilever shape. A sensor 4 such as an acceleration sensor that detects the intensity of vibration generated by the collision between the powder and the diaphragm 3 in time series is attached to the diaphragm 3, and the sensor 4 is connected to the signal processing device 5.
[0013]
The signal processing device 5 includes a main amplifier 5a, a bandpass filter 5b, an auxiliary amplifier 5c, an effective value conversion circuit 5d, an A / D converter 5e, and an arithmetic device 5f.
[0014]
The vibration intensity detection signal sent from the sensor 4 is amplified by the main amplifier 5a, the signal other than the predetermined frequency band is removed by the band-pass filter 5b, amplified by the auxiliary amplifier 5c, and the effective value conversion circuit 5d. Is converted into a DC signal having a value corresponding to the effective value corresponding to the intensity of the frequency band, A / D converted by the A / D converter 5e, and input to the arithmetic unit 5f.
[0015]
The frequency band of the signal passing through the bandpass filter 5b is determined so as to include the natural frequency of the vibration generated by the collision between the powder and the diaphragm 3, and the specific value indicates the particle size as desired. The lower limit value is preferably 500 Hz or more. Thereby, the intensity of a predetermined frequency band including the natural frequency of the vibration generated by the collision between the powder and the diaphragm 3 is detected.
[0016]
The computing device 5f is configured by a computer, stores a previously determined relationship between the particle size of the particle 2 and the vibration intensity of the frequency band, and the particle 2 corresponding to the detected vibration intensity of the frequency band. The diameter is obtained from the stored relationship. Further, an input device 7 such as a keyboard, a data recording unit 8 such as an external storage device or a printer, and a display unit 9 such as a CRT or a liquid crystal display are connected to the arithmetic device 5f, and an operation signal is input from the input device 7. The obtained particle size is output to the data recording unit 8 and the display unit 9.
[0017]
FIG. 2 (1) shows an example of the vibration intensity for each frequency generated by the collision between the powder and the diaphragm 3, and in this embodiment, a predetermined frequency including the natural frequency in the range indicated by A in the figure. An effective value is obtained as the vibration intensity of the band (for example, 3400 to 4600 Hz). The vibration strength here is calculated by calculating the effective value of the alternating current signal according to the following formula, but it may be obtained by using the time average of the absolute value of the alternating current signal or the like.
[0018]
[Expression 1]

[0019]
FIG. 2 (2) shows the relationship between the intensity of the frequency band and the particle size of vibrations caused by the collision between the powder 3 in a fluid state composed of particles 2 having a predetermined particle size and the diaphragm 3. An example is shown, and ◯ in the figure indicates a measurement point. In addition, the measuring method of a particle size (indicating an average particle size) is to screen a sample using a plurality of specific mesh sieves, and the mesh where the integrated weight is 50% is taken as the sample particle size. From this, it can be confirmed that the vibration intensity in the frequency band correlates with the particle diameter, and that the vibration intensity in the frequency band increases as the particle diameter increases. Therefore, the particle size of the powder constituent particles 2 corresponding to the detected value of the vibration intensity in the frequency band can be obtained from the stored relationship between the particle diameter and the vibration intensity in the frequency band. The straight line B shows an example of the relationship between the particle size stored in the arithmetic device 5f and the vibration intensity in the frequency band.
[0020]
According to the above configuration, the correlation between the particle size of the powder constituent particle 2 and the vibration strength is not affected by the flow rate or surface property of the powder constituent particle 2, so the influence of the flow rate or surface property is not affected. The particle size can be measured with little accuracy. In addition, by setting the lower limit value of the frequency band to 500 Hz or more, and preferably selecting a higher order natural frequency, it is possible to prevent the influence of noise based on surrounding low frequency vibrations and the like.
[0021]
A second embodiment of the present invention will be described with reference to FIGS.
In the second embodiment, the powder is caused to flow in the first and

second granulators

11 and 12 in order to perform granulation.
[0022]
The first granulator 11 includes a stirring vessel 11a having a cylindrical shape with a horizontal axis, a blade-like stirring member 11d rotated around the horizontal axis 11c by a motor 11b in the vessel 11a, and the stirring member A blade-shaped crushing member 11e provided on the inner peripheral portion of the container 11a facing the outer peripheral portion of the 11d rotating shaft 11c. The crushing member 11e is located in the powder flow region, is supported in a cantilever shape by the container 11a, and is driven to rotate about the axis along the radial direction of the container 11a by the prime mover 11f. The powder is fluidized by being stirred by the stirring member 11d in the container 11a and pulverized by the pulverizing member 11e. In addition, a granulating liquid for granulating the powder, a reaction liquid that causes a chemical reaction by contacting with the powder, and the like are supplied into the container 11a from an unillustrated pipe. A sensor 14 a for detecting the intensity of vibration generated by the collision between the powder and the pulverizing member 11 e is attached to the prime mover 11 f of the pulverizing member 11 e, and the sensor 14 a is connected to the signal processing device 15.
[0023]
The second granulating apparatus 12 includes a stirring vessel 12a having a cylindrical shape with a vertical axis, a blade-like stirring member 12d driven to rotate around a vertical axis 12c by a prime mover 12b in the vessel 12a, and the stirring member A blade-shaped crushing member 12e provided on the inner peripheral portion of the container 12a facing the outer peripheral portion of the rotating shaft 12c of 12d. The crushing member 12e is located in the powder flow region, is supported in a cantilever shape by the container 12a, and is rotationally driven by the prime mover 12f about the axial center along the radial direction of the container 12a. The powder is fluidized by being stirred by the stirring member 12d in the container 12a and pulverized by the pulverizing member 12e. In addition, a granulating liquid for granulating the powder, a reaction liquid that causes a chemical reaction when brought into contact with the powder, and the like are supplied into the container 12a from an unillustrated pipe. A sensor 14b for detecting the intensity of vibration generated by the collision between the powder and the pulverizing member 12e is attached to the prime mover 12f of the pulverizing member 12e, and the sensor 14b is connected to the signal processing device 15.
[0024]
The signal processing device 15 includes first and second main amplifiers 15a ′ and 15a ″, first and second bandpass filters 15b ′ and 15b ″, first and second auxiliary amplifiers 15c ′ and 15c ″, first, Second effective value conversion circuits 15d 'and 15d ", first and second A / D converters 15e' and 15e", and a control device 15f are included.
[0025]
The first main amplifier 15a ′, the bandpass filter 15b ′, the auxiliary amplifier 15c ′, the effective value conversion circuit 15d ′, and the A / D converter 15e ′ are vibration intensities sent from the sensor 14a of the first granulating device 11. The second main amplifier 15a ″, the band-pass filter 15b ″, the auxiliary amplifier 15c ″, the effective value conversion circuit 15d ″, and the A / D converter 15e ″ are detected by the sensor 14b of the second granulating device 12. Are processed in the same manner as the signal processing device 5 of the first embodiment, and each processing signal is input to the control device 15f.
[0026]
The frequency band of the signal passing through the first bandpass filter 15b ′ is determined so as to include the natural frequency of the vibration generated by the collision between the powder and the pulverizing member 11e of the first granulating device 11, and the second band. The frequency band of the signal passing through the pass filter 15b ″ is determined so as to include the natural frequency of the vibration generated by the collision between the powder and the pulverizing member 12e of the second granulating device 12, and each specific value. Can be determined by experiment so that the particle size can be determined with a desired accuracy, and each lower limit value is preferably 500 Hz or more, which is caused by collision between the powder and each of the grinding

members

11e and 12e. The intensity of a predetermined frequency band including the natural frequency of each vibration is detected.
[0027]
The control device 15f is configured by a computer, and is connected to an input device 17 such as a keyboard, a data recording unit 18 such as an external storage device or a printer, and a display unit 19 such as a CRT or a liquid crystal display.
[0028]
The control device 15f has a built-in storage device, and the particle size of the powder constituent particles granulated in the first granulating device 11 and the vibration intensity in the frequency band of the signal passing through the first bandpass filter 15b ′ are preliminarily determined. The predetermined relationship is the vibration intensity in the frequency band of the signal passing through the first band-pass filter 15b 'determined in advance corresponding to the target particle size of the powder constituent particles granulated in the first granulator 11. 1 predetermined value, a predetermined relationship between the particle size of the powder constituent particles granulated in the second granulator 12 and the vibration intensity in the frequency band of the signal passing through the second bandpass filter 15b ″, and 2 The second set value which is the vibration intensity in the frequency band of the signal passing through the second bandpass filter 15b ″ obtained in advance corresponding to the target particle size of the powder constituent particles granulated in the granulator 12 is stored. To do.
[0029]
Then, the control device 15f has a particle size corresponding to the vibration intensity in the frequency band detected in the first granulation device 11 and a particle corresponding to the vibration intensity in the frequency band detected in the second granulation device 12. The diameter is calculated, and the calculation result is output to the data recording unit 18 and the display unit 19.
[0030]
Moreover, the control device 15f stops the

prime movers

11b and 11f of the first granulation device 11 when the vibration intensity of the frequency band detected by the first granulation device 11 is the first set value. When the control signal is output, the granulation by the first granulator 11 is terminated, and the vibration intensity of the frequency band detected by the second granulator 12 is the second set value, the second granulation is performed. A control signal for stopping the

prime movers

12b and 12f of the apparatus 12 is output, and the granulation by the second granulation apparatus 12 is terminated.
[0031]
FIG. 4 (1) shows an example of the vibration intensity at each frequency generated by the collision between the powder and the pulverizing member 11e in the first granulator 11, and in this embodiment, the natural vibration in the range indicated by C in the figure. An effective value is obtained as the vibration intensity in a predetermined frequency band including numbers (for example, 2800 to 3200 Hz).
[0032]
FIG. 4 (2) shows the vibration generated by the collision when the powder in a fluid state composed of particles having a predetermined particle diameter collide with the pulverizing member 11e in the first granulator 11. 1 shows an example of the relationship between the intensity of the above frequency band and the particle diameter, and ◯ in the figure indicates a measurement point. From this, the particle size correlates with the vibration intensity in the frequency band, and it can be confirmed that the vibration intensity increases as the particle diameter increases. Therefore, the particle size of the powder constituent particles corresponding to the detected value of the vibration strength can be obtained from the stored relationship between the vibration strength and the particle size of the frequency band. The straight line D shows an example of the relationship between the particle size stored in the control device 15f and the vibration intensity in the frequency band. Further, when storing the first set value, which is the vibration intensity in the frequency band corresponding to the target particle diameter of the powder constituent particles, the target particle diameter and the vibration intensity in the frequency band are expressed by the relationship indicated by the straight line D. Can be obtained. Similarly, in the second granulator 12, a correlation between the particle size and the vibration intensity in the frequency band can be obtained.
[0033]
According to the above configuration, the correlation between the particle size of the powder constituent particles and the vibration intensity in the frequency band is not affected by the flow rate or surface properties of the powder constituent particles. Regardless of this, the particle diameter can be obtained with high accuracy, and the end point of granulation can be obtained with high accuracy. Further, by setting the lower limit value of each frequency band to 500 Hz or more, preferably by selecting a higher order as each natural frequency, the end point of the granulation is based on the surrounding low frequency vibration or the like. It can be obtained more accurately without being affected by noise. In addition, the intensity of each frequency band of the vibration generated by the collision between the pulverizing

members

11e and 12e and the powder well reflects the particle size of the powder constituent particles. Therefore, by detecting the vibration intensity of the frequency band. The particle size can be obtained with high accuracy, and the end point of granulation can be obtained with high accuracy.
[0034]
A third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the second embodiment are denoted by the same reference numerals.
As shown in FIGS. 5 and 6, the difference between the third embodiment and the second embodiment is that a vibration isolating member 20 such as a vibration isolating rubber is attached to the stirring container 11 a of the first granulating device 11. The first diaphragm 21a, the position adjusting member 21b, and the second diaphragm 22 integrated with each other are attached to the stirring vessel 11a via the vibration isolating member 20. The first diaphragm 21a and the position adjusting member 21b are disposed inside the stirring container 11a, and the second diaphragm 22 is disposed outside the stirring container 11a. The length of the position adjusting member 21b may or may not be appropriately changed so that the powder appropriately collides with the first diaphragm 21a. In the stirring vessel 11a, the flowing powder collides with the first vibration plate 21a and vibration is generated in the first vibration plate 21a. This vibration is also transmitted to the second vibration plate 22 and also vibrated in the second vibration plate 22. Arise. Therefore, the sensor 23 for detecting the vibration generated in the vibration plate can measure the particle size of the powder in the stirring vessel 11a regardless of which vibration plate is attached. However, in consideration of deterioration due to the environment around the sensor 23 and convenience of maintenance, it is better to attach it to the second diaphragm 22.
Instead of detecting the vibration intensity generated by the collision between the powder and the pulverizing member 11e in the second embodiment, the sensor 23 detects the intensity of the vibration generated by the collision between the first diaphragm 21a and the powder. Is attached to the second diaphragm 22, and the sensor 23 is connected to the signal processing device 15 '. Further, a gate valve (not shown) for taking out powder from the stirring vessel 11a and a gate valve driving device 25 are attached. Since the vibration preventing member can prevent the influence of noise based on the surrounding low frequency vibration or the like, the end point of granulation can be obtained with high accuracy or the particle size can be brought close to a desired value with high accuracy.
[0035]
The second granulating device 12 is the same as that of the second embodiment, and a sensor 14b for detecting the intensity of vibration caused by the collision between the powder and the pulverizing member 12e is connected to the signal processing device 15 '.
[0036]
The signal processing device 15 ′ of the third embodiment is the same as the signal processing device 15 of the second embodiment except for the control device, and the collision between the powder in the first granulating device 11 and the first diaphragm 21. The intensity of a predetermined frequency band including the natural frequency of the vibration generated by the above, and the intensity of a predetermined frequency band including the natural frequency of the vibration generated by the collision between the powder and the pulverizing member 12e in the second granulator 12 Are detected in time series.
[0037]
The control device 15f ′ of the signal processing device 15 ′ according to the third embodiment includes a first bandpass filter 15b ′ corresponding to the elapsed time from the start of granulation in the first granulation device 11 and the reference particle size of the powder constituent particles. The first predetermined relationship with the vibration intensity in the frequency band of the signal passing through the first is stored, and also corresponds to the elapsed time from the start of granulation in the second granulator 12 and the reference particle size of the powder constituent particles The second predetermined relationship with the vibration intensity of the frequency band passing through the second band pass filter 15b ″ is stored. Each reference particle size is determined when the relationship between the elapsed time and the intensity of the frequency band is satisfied. The target particle size of the powder constituent particles at that time is set to an arbitrary value, and can be set to an arbitrary value.A solid line E in Fig. 7 indicates the elapsed time from the start of granulation in the first granulator 11. And the standard particle size of powder constituent particles Serial shows an example of the relationship between the vibration intensity of the frequency band.
[0038]
The control device 15f ′ compares the vibration intensity of the frequency band detected by the first granulation device 11 with the first relationship at an elapse of an arbitrary time from the start of granulation, and detects the vibration of the detected frequency band. The difference between the strength and the vibration intensity in the frequency band corresponding to the reference particle size is obtained, and the granulation conditions of the first granulator 11 are changed so as to reduce the difference. Further, the control device 15f ′ compares the vibration intensity of the frequency band detected by the second granulating device 12 with the second relationship at an elapse of an arbitrary time from the start of granulation, and compares the detected frequency band of the detected frequency band. The difference between the vibration intensity and the vibration intensity in the frequency band corresponding to the reference particle diameter is obtained, and the granulation conditions of the second granulator 12 are changed so as to reduce the difference. The relationship between the difference and the change amount of the granulation condition is determined and stored in advance.
[0039]
For example, when granulation is performed by a batch process, the rotational speeds of the stirring

members

11d and 12d and the pulverizing

members

11e and 12e of the granulating

apparatuses

11 and 12 can be set as granulation conditions to be changed. , 11f, 12b, and 12f can be used to change the granulation conditions. When granulation is performed by a continuous process, the residence time of the powder can be set as a granulation condition. For example, an opening control signal of the gate valve for taking out the powder from the stirring vessel 11a is used as the gate valve driving device 25. The granulation conditions can be changed by sending to.
[0040]
A solid line F in FIG. 7 shows an example of the relationship between the elapsed time from the start of granulation and the detected vibration intensity of the frequency band. In this case, the vibration intensity of the detected frequency band is smaller than the vibration intensity of the frequency band corresponding to the reference particle diameter by δa in the elapsed time of the arbitrary time ta from the start of granulation. That is, the particle size of the powder constituent particles is smaller by a value corresponding to the δa than the reference particle size, which is a target value when an arbitrary time has elapsed. In this case, in order to reduce the rotational speed of the stirring

members

11d and 12d and the pulverizing

members

11e and 12e by an amount stored in advance according to the difference δa, or to increase the residence time of the powder, The opening degree of the extraction gate valve can be reduced.
[0041]
Moreover, the continuous line G in FIG. 7 shows another example of the relationship between the elapsed time from the start of granulation and the detected vibration intensity of the frequency band. In this case, the vibration intensity of the detected frequency band is larger by δb in the figure than the vibration intensity of the frequency band corresponding to the reference particle diameter at an elapsed time ta from the start of granulation. In other words, the particle size of the powder constituent particles is larger by a value corresponding to the δb than the reference particle size, which is the target value when an arbitrary time has elapsed. In this case, in order to increase the rotational speed of the agitating

members

11d and 12d and the pulverizing

members

11e and 12e by an amount stored in advance according to the difference δb, or to reduce the residence time of the powder, The opening degree of the body extraction gate valve can be increased. Others are the same as in the second embodiment.
[0042]
FIG. 8 (1) shows an example of the vibration intensity for each frequency of the second diaphragm 22 generated by the collision of the powder and the first diaphragm 21 in the first granulator 11 in the third embodiment. In the present embodiment, vibration intensity in a predetermined frequency band (for example, 2200 to 2700 Hz) including the natural frequency in the range indicated by H in the figure is detected. FIG. 8B shows the vibration of the second diaphragm 22 caused by the collision when the powder in a fluid state composed of particles having a predetermined particle diameter and the first diaphragm 21 collide with each other. 1 shows an example of the relationship between the intensity and the particle size in the above frequency band. This confirms that the particle size and the vibration intensity in the frequency band are correlated. The straight line I is an example showing the correlation. The first relationship between the elapsed time from the start of granulation in the first granulator 11 and the vibration intensity in the frequency band corresponding to the reference particle size of the powder constituent particles is indicated by the straight line H. The relationship between the reference particle size and the vibration intensity in the frequency band can be obtained from the relationship. Similarly, in the second granulator 12, a correlation between the particle size and the vibration intensity in the frequency band can be obtained.
[0043]
According to the third embodiment, the difference between the vibration intensity in the frequency band detected at an arbitrary time from the start of granulation and the vibration intensity in the frequency band corresponding to the reference particle diameter is the powder constituent particles at that time. This corresponds to the difference between the actual particle size and the reference particle size. The reference particle size can be set arbitrarily. Therefore, by changing the granulation conditions so as to reduce the difference, the particle size of the powder constituent particles is brought close to an arbitrary target value without being affected by the flow rate and surface properties of the powder constituent particles. be able to. From FIG. 7, it can be confirmed that the particle size of the powder constituent particles approaches the reference particle size by changing the granulation conditions as described above at the time ta after the start of granulation. Furthermore, by setting the lower limit value of the frequency band to 500 Hz or more, preferably by selecting a higher-order one as its natural frequency, without being affected by noise due to surrounding low frequency vibrations, etc. The particle size can be brought closer to the target value with higher accuracy. Moreover, in the 1st granulator 11, since the influence of the noise based on the surrounding low frequency vibration etc. can be prevented with the vibration isolator 20, a particle size can be closely approached to a desired value. Further, in the second granulator 12, the vibration intensity in the frequency band generated by the collision between the pulverizing member 12e and the powder well reflects the particle diameter of the powder constituent particles. By detecting, the particle diameter can be brought close to the target value with high accuracy. In the second embodiment as well, a diaphragm is provided via a vibration isolating member similar to that of the third embodiment, and the intensity of the frequency band including the natural frequency of vibration generated by the collision between the diaphragm and the powder is increased. You may make it ask.
[0044]
In the granulation process in the second and third embodiments, when supplying a reaction liquid or the like that causes a chemical reaction by contacting the powder in the stirring

containers

11a and 12a, the powder constituting particles are aggregated. The new particles produced by this process contain substances that react chemically during the granulation process. In this case, even if the surface properties of the powder constituent particles fluctuate due to the chemical reaction, the correlation between the particle size and the vibration intensity in the frequency band is not affected by the surface properties of the powder constituent particles. The diameter and the end point of granulation can be obtained with high accuracy, or the particle size can be brought close to the target value with high accuracy.
[0045]
FIG. 9 (1) shows the fourth embodiment, and when the powder is conveyed in the direction of the arrow in the drawing by a conveying device 31 such as a belt conveyor or a vibration conveyor, it is cantilevered at a position where it collides with the powder in the middle of the conveyance. A beam-shaped diaphragm 32 is provided. As a result, the powder flows relative to the vibration plate 32, so that the strength of a predetermined frequency band including the natural frequency of vibration generated by the collision between the vibration plate 32 and the powder is, for example, vibration. It can detect with the sensor 33 attached to the board 32, and can obtain | require the particle size of the powder constituent particle | grains 2 similarly to the said 1st Embodiment.
[0046]
FIG. 9 (2) shows the fifth embodiment, and includes the natural frequency of the vibration generated by the collision between the powder and the duct 41 when the powder flows by being transported by air in the duct 41. The intensity of a predetermined frequency band can be detected by, for example, the sensor 42 attached to the duct 41, and the particle size of the powder constituent particles 2 can be obtained in the same manner as in the first embodiment.
[0047]
The present invention is not limited to the above embodiments. For example, the agitation container itself of the granulator vibrates when the powder collides with its inner peripheral part during granulation, so that the vibration intensity in a predetermined frequency band of the agitation container itself is detected. Also good. Further, instead of obtaining an effective value as the vibration intensity in a predetermined frequency band, the integrated value of the vibration intensity corresponding to each frequency obtained by fast Fourier transform of the vibration intensity detection signal in the frequency band, An average value or a maximum value may be obtained. In addition, the vibration intensity in the frequency band is obtained using a bandpass filter and an effective value conversion circuit, so that the vibration intensity is obtained more quickly than that obtained using a fast Fourier transform, and the composition of the powder in a fluid state The particle size can be measured in substantially real time. Moreover, since the frequency band can be made constant regardless of the granulation operation conditions such as the number of rotations of the stirring member, it is not necessary to change the center frequency of the bandpass filter, and the apparatus configuration can be prevented from becoming complicated.
[0048]
【The invention's effect】
According to the present invention, a general-purpose particle size measuring method capable of accurately obtaining the particle size without being affected by the particle flow rate, the surface property of the particle, and surrounding noise, and the end point of granulation with high accuracy. Therefore, it is possible to provide a granulation control method that can accurately bring the particle size close to a desired value during granulation.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a configuration for carrying out a particle size measuring method according to a first embodiment of the present invention.
FIG. 2 is a diagram showing vibration intensity for each frequency in the first embodiment of the present invention, and (2) is a diagram showing the relationship between vibration intensity and particle size in a predetermined frequency band.
FIG. 3 is an explanatory diagram of a configuration for carrying out a granulation control method according to a second embodiment of the present invention.
FIG. 4 is a diagram showing the vibration intensity for each frequency in the second embodiment of the present invention, and (2) is a diagram showing the relationship between the vibration intensity and the particle size in a predetermined frequency band.
FIG. 5 is an explanatory diagram of a configuration for carrying out a granulation control method according to a third embodiment of the present invention.
FIG. 6 is an explanatory diagram of a main part of a configuration for carrying out a granulation control method according to a third embodiment of the present invention.
FIG. 7 is a diagram showing a relationship between time and vibration intensity in a predetermined frequency band in the granulation control method according to the third embodiment of the present invention.
8A and 8B are diagrams illustrating vibration intensity for each frequency according to the third embodiment of the present invention, and FIG. 8B is a diagram illustrating a relationship between vibration intensity and particle size in a predetermined frequency band.
FIG. 9 is an explanatory diagram of a configuration for carrying out a particle size measuring method according to a fourth embodiment of the present invention, and (2) is a configuration for carrying out a particle size measuring method according to a fifth embodiment. Illustration
[Explanation of symbols]
2 particles
3, 21, 22, 32 Diaphragm
4, 14a, 14b, 23, 33, 42 Sensor
5b, 15b ', 15b "bandpass filters
5d, 15d ', 15d "RMS value conversion circuit
5f arithmetic unit
11, 12 Granulator
11e, 12e Crushing member
15f, 15f 'control device
20 Anti-vibration member

Claims

When measuring the particle size of the particles constituting the powder in a fluid state,
Detecting the intensity of a predetermined frequency band including the natural frequency of vibration generated in the part located in the flow region of the powder due to the collision between the part located in the flow region of the powder and the powder,
A particle diameter measuring method, wherein a particle diameter corresponding to the detected vibration intensity in the frequency band is obtained based on a relationship obtained in advance between the particle diameter of the particle and the vibration intensity in the frequency band.

When powder is flowed for granulation, the natural frequency of the vibration generated in the part located in the flow region of the powder due to collision between the part located in the flow region of the powder and the powder Detect the intensity of a predetermined frequency band including
A particle diameter measuring method, wherein a particle diameter corresponding to the detected vibration intensity in the frequency band is obtained based on a relationship obtained in advance between the particle diameter of the particle and the vibration intensity in the frequency band.

The particle size measurement method according to claim 1 or 2, wherein a lower limit value of the frequency band is 500 Hz or more.

The particle size measuring method according to claim 2 or 3 , wherein the new particles generated by agglomerating powder constituent particles in the granulation process include a substance that chemically reacts in the granulation process.

When powder is flowed for granulation, the natural frequency of vibration generated in the part located in the flow region of the powder due to collision between the part located in the flow region of the powder and the powder Detect the intensity of a predetermined frequency band including
A granulation control method, wherein the granulation is terminated when the detected vibration intensity in the frequency band is a preset value corresponding to the target particle size of the powder constituent particles.

When powder is flowed for granulation, the natural frequency of vibration generated in the part located in the flow region of the powder due to collision between the part located in the flow region of the powder and the powder Detecting the intensity of a predetermined frequency band including
A predetermined relationship between the vibration intensity in the frequency band detected at an arbitrary time point from the start of granulation, the elapsed time from the start of granulation and the vibration intensity in the frequency band corresponding to the reference particle diameter of the powder constituent particles; Compare and
A granulation control method, wherein the granulation conditions are changed so as to reduce a difference between the detected vibration intensity in the frequency band and the vibration intensity in the frequency band corresponding to the reference particle diameter.

The powder is flowed by being agitated by an agitating member that is rotationally driven about the axis in the container, and can be rotationally driven on the inner peripheral portion of the container that faces the outer peripheral portion of the rotating shaft of the agitating member. It is crushed by the crushing member provided,
The granulation control method according to claim 5 or 6, wherein as the vibration strength, a vibration strength generated by a collision between the pulverized member and the powder is detected.